Merge remote-tracking branch 'upstream/master' into 503-hover-doc-links

64 files changed, 24933 insertions, 0 deletions

diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
new file mode 100644
index 000000000..9ecf43e5a
--- /dev/null
+++ b/crates/ide/Cargo.toml
@@ -0,0 +1,37 @@
+[package]
+name = "ide"
+version = "0.0.0"
+license = "MIT OR Apache-2.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+
+[lib]
+doctest = false
+
+[dependencies]
+either = "1.5.3"
+indexmap = "1.3.2"
+itertools = "0.9.0"
+log = "0.4.8"
+rustc-hash = "1.1.0"
+oorandom = "11.1.2"
+pulldown-cmark-to-cmark = "5.0.0"
+pulldown-cmark = {version = "0.7.2", default-features = false}
+
+stdx = { path = "../stdx" }
+syntax = { path = "../syntax" }
+text_edit = { path = "../text_edit" }
+base_db = { path = "../base_db" }
+ide_db = { path = "../ide_db" }
+cfg = { path = "../cfg" }
+profile = { path = "../profile" }
+test_utils = { path = "../test_utils" }
+assists = { path = "../assists" }
+ssr = { path = "../ssr" }
+
+# ide should depend only on the top-level `hir` package. if you need
+# something from some `hir_xxx` subpackage, reexport the API via `hir`.
+hir = { path = "../hir" }
+
+[dev-dependencies]
+expect-test = "0.1"
diff --git a/crates/ide/src/call_hierarchy.rs b/crates/ide/src/call_hierarchy.rs
new file mode 100644
index 000000000..58e26b94c
--- /dev/null
+++ b/crates/ide/src/call_hierarchy.rs
@@ -0,0 +1,393 @@
+//! Entry point for call-hierarchy
+
+use indexmap::IndexMap;
+
+use hir::Semantics;
+use ide_db::RootDatabase;
+use syntax::{ast, match_ast, AstNode, TextRange};
+
+use crate::{
+    call_info::FnCallNode, display::ToNav, goto_definition, references, FilePosition,
+    NavigationTarget, RangeInfo,
+};
+
+#[derive(Debug, Clone)]
+pub struct CallItem {
+    pub target: NavigationTarget,
+    pub ranges: Vec<TextRange>,
+}
+
+impl CallItem {
+    #[cfg(test)]
+    pub(crate) fn assert_match(&self, expected: &str) {
+        let actual = self.debug_render();
+        test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
+    }
+
+    #[cfg(test)]
+    pub(crate) fn debug_render(&self) -> String {
+        format!("{} : {:?}", self.target.debug_render(), self.ranges)
+    }
+}
+
+pub(crate) fn call_hierarchy(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    goto_definition::goto_definition(db, position)
+}
+
+pub(crate) fn incoming_calls(db: &RootDatabase, position: FilePosition) -> Option<Vec<CallItem>> {
+    let sema = Semantics::new(db);
+
+    // 1. Find all refs
+    // 2. Loop through refs and determine unique fndef. This will become our `from: CallHierarchyItem,` in the reply.
+    // 3. Add ranges relative to the start of the fndef.
+    let refs = references::find_all_refs(&sema, position, None)?;
+
+    let mut calls = CallLocations::default();
+
+    for reference in refs.info.references() {
+        let file_id = reference.file_range.file_id;
+        let file = sema.parse(file_id);
+        let file = file.syntax();
+        let token = file.token_at_offset(reference.file_range.range.start()).next()?;
+        let token = sema.descend_into_macros(token);
+        let syntax = token.parent();
+
+        // This target is the containing function
+        if let Some(nav) = syntax.ancestors().find_map(|node| {
+            match_ast! {
+                match node {
+                    ast::Fn(it) => {
+                        let def = sema.to_def(&it)?;
+                        Some(def.to_nav(sema.db))
+                    },
+                    _ => None,
+                }
+            }
+        }) {
+            let relative_range = reference.file_range.range;
+            calls.add(&nav, relative_range);
+        }
+    }
+
+    Some(calls.into_items())
+}
+
+pub(crate) fn outgoing_calls(db: &RootDatabase, position: FilePosition) -> Option<Vec<CallItem>> {
+    let sema = Semantics::new(db);
+    let file_id = position.file_id;
+    let file = sema.parse(file_id);
+    let file = file.syntax();
+    let token = file.token_at_offset(position.offset).next()?;
+    let token = sema.descend_into_macros(token);
+    let syntax = token.parent();
+
+    let mut calls = CallLocations::default();
+
+    syntax
+        .descendants()
+        .filter_map(|node| FnCallNode::with_node_exact(&node))
+        .filter_map(|call_node| {
+            let name_ref = call_node.name_ref()?;
+
+            if let Some(func_target) = match &call_node {
+                FnCallNode::CallExpr(expr) => {
+                    //FIXME: Type::as_callable is broken
+                    let callable = sema.type_of_expr(&expr.expr()?)?.as_callable(db)?;
+                    match callable.kind() {
+                        hir::CallableKind::Function(it) => {
+                            let fn_def: hir::Function = it.into();
+                            let nav = fn_def.to_nav(db);
+                            Some(nav)
+                        }
+                        _ => None,
+                    }
+                }
+                FnCallNode::MethodCallExpr(expr) => {
+                    let function = sema.resolve_method_call(&expr)?;
+                    Some(function.to_nav(db))
+                }
+            } {
+                Some((func_target, name_ref.syntax().text_range()))
+            } else {
+                None
+            }
+        })
+        .for_each(|(nav, range)| calls.add(&nav, range));
+
+    Some(calls.into_items())
+}
+
+#[derive(Default)]
+struct CallLocations {
+    funcs: IndexMap<NavigationTarget, Vec<TextRange>>,
+}
+
+impl CallLocations {
+    fn add(&mut self, target: &NavigationTarget, range: TextRange) {
+        self.funcs.entry(target.clone()).or_default().push(range);
+    }
+
+    fn into_items(self) -> Vec<CallItem> {
+        self.funcs.into_iter().map(|(target, ranges)| CallItem { target, ranges }).collect()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FilePosition;
+
+    use crate::mock_analysis::analysis_and_position;
+
+    fn check_hierarchy(
+        ra_fixture: &str,
+        expected: &str,
+        expected_incoming: &[&str],
+        expected_outgoing: &[&str],
+    ) {
+        let (analysis, pos) = analysis_and_position(ra_fixture);
+
+        let mut navs = analysis.call_hierarchy(pos).unwrap().unwrap().info;
+        assert_eq!(navs.len(), 1);
+        let nav = navs.pop().unwrap();
+        nav.assert_match(expected);
+
+        let item_pos =
+            FilePosition { file_id: nav.file_id, offset: nav.focus_or_full_range().start() };
+        let incoming_calls = analysis.incoming_calls(item_pos).unwrap().unwrap();
+        assert_eq!(incoming_calls.len(), expected_incoming.len());
+
+        for call in 0..incoming_calls.len() {
+            incoming_calls[call].assert_match(expected_incoming[call]);
+        }
+
+        let outgoing_calls = analysis.outgoing_calls(item_pos).unwrap().unwrap();
+        assert_eq!(outgoing_calls.len(), expected_outgoing.len());
+
+        for call in 0..outgoing_calls.len() {
+            outgoing_calls[call].assert_match(expected_outgoing[call]);
+        }
+    }
+
+    #[test]
+    fn test_call_hierarchy_on_ref() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn callee() {}
+fn caller() {
+    call<|>ee();
+}
+"#,
+            "callee FN FileId(1) 0..14 3..9",
+            &["caller FN FileId(1) 15..44 18..24 : [33..39]"],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_on_def() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn call<|>ee() {}
+fn caller() {
+    callee();
+}
+"#,
+            "callee FN FileId(1) 0..14 3..9",
+            &["caller FN FileId(1) 15..44 18..24 : [33..39]"],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_in_same_fn() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn callee() {}
+fn caller() {
+    call<|>ee();
+    callee();
+}
+"#,
+            "callee FN FileId(1) 0..14 3..9",
+            &["caller FN FileId(1) 15..58 18..24 : [33..39, 47..53]"],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_in_different_fn() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn callee() {}
+fn caller1() {
+    call<|>ee();
+}
+
+fn caller2() {
+    callee();
+}
+"#,
+            "callee FN FileId(1) 0..14 3..9",
+            &[
+                "caller1 FN FileId(1) 15..45 18..25 : [34..40]",
+                "caller2 FN FileId(1) 47..77 50..57 : [66..72]",
+            ],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_in_tests_mod() {
+        check_hierarchy(
+            r#"
+//- /lib.rs cfg:test
+fn callee() {}
+fn caller1() {
+    call<|>ee();
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_caller() {
+        callee();
+    }
+}
+"#,
+            "callee FN FileId(1) 0..14 3..9",
+            &[
+                "caller1 FN FileId(1) 15..45 18..25 : [34..40]",
+                "test_caller FN FileId(1) 95..149 110..121 : [134..140]",
+            ],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_in_different_files() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+mod foo;
+use foo::callee;
+
+fn caller() {
+    call<|>ee();
+}
+
+//- /foo/mod.rs
+pub fn callee() {}
+"#,
+            "callee FN FileId(2) 0..18 7..13",
+            &["caller FN FileId(1) 27..56 30..36 : [45..51]"],
+            &[],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_outgoing() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn callee() {}
+fn call<|>er() {
+    callee();
+    callee();
+}
+"#,
+            "caller FN FileId(1) 15..58 18..24",
+            &[],
+            &["callee FN FileId(1) 0..14 3..9 : [33..39, 47..53]"],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_outgoing_in_different_files() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+mod foo;
+use foo::callee;
+
+fn call<|>er() {
+    callee();
+}
+
+//- /foo/mod.rs
+pub fn callee() {}
+"#,
+            "caller FN FileId(1) 27..56 30..36",
+            &[],
+            &["callee FN FileId(2) 0..18 7..13 : [45..51]"],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_incoming_outgoing() {
+        check_hierarchy(
+            r#"
+//- /lib.rs
+fn caller1() {
+    call<|>er2();
+}
+
+fn caller2() {
+    caller3();
+}
+
+fn caller3() {
+
+}
+"#,
+            "caller2 FN FileId(1) 33..64 36..43",
+            &["caller1 FN FileId(1) 0..31 3..10 : [19..26]"],
+            &["caller3 FN FileId(1) 66..83 69..76 : [52..59]"],
+        );
+    }
+
+    #[test]
+    fn test_call_hierarchy_issue_5103() {
+        check_hierarchy(
+            r#"
+fn a() {
+    b()
+}
+
+fn b() {}
+
+fn main() {
+    a<|>()
+}
+"#,
+            "a FN FileId(1) 0..18 3..4",
+            &["main FN FileId(1) 31..52 34..38 : [47..48]"],
+            &["b FN FileId(1) 20..29 23..24 : [13..14]"],
+        );
+
+        check_hierarchy(
+            r#"
+fn a() {
+    b<|>()
+}
+
+fn b() {}
+
+fn main() {
+    a()
+}
+"#,
+            "b FN FileId(1) 20..29 23..24",
+            &["a FN FileId(1) 0..18 3..4 : [13..14]"],
+            &[],
+        );
+    }
+}
diff --git a/crates/ide/src/call_info.rs b/crates/ide/src/call_info.rs
new file mode 100644
index 000000000..7e83a2381
--- /dev/null
+++ b/crates/ide/src/call_info.rs
@@ -0,0 +1,742 @@
+//! FIXME: write short doc here
+use either::Either;
+use hir::{Docs, HirDisplay, Semantics, Type};
+use ide_db::RootDatabase;
+use stdx::format_to;
+use syntax::{
+    ast::{self, ArgListOwner},
+    match_ast, AstNode, SyntaxNode, SyntaxToken, TextRange, TextSize,
+};
+use test_utils::mark;
+
+use crate::FilePosition;
+
+/// Contains information about a call site. Specifically the
+/// `FunctionSignature`and current parameter.
+#[derive(Debug)]
+pub struct CallInfo {
+    pub doc: Option<String>,
+    pub signature: String,
+    pub active_parameter: Option<usize>,
+    parameters: Vec<TextRange>,
+}
+
+impl CallInfo {
+    pub fn parameter_labels(&self) -> impl Iterator<Item = &str> + '_ {
+        self.parameters.iter().map(move |&it| &self.signature[it])
+    }
+    pub fn parameter_ranges(&self) -> &[TextRange] {
+        &self.parameters
+    }
+    fn push_param(&mut self, param: &str) {
+        if !self.signature.ends_with('(') {
+            self.signature.push_str(", ");
+        }
+        let start = TextSize::of(&self.signature);
+        self.signature.push_str(param);
+        let end = TextSize::of(&self.signature);
+        self.parameters.push(TextRange::new(start, end))
+    }
+}
+
+/// Computes parameter information for the given call expression.
+pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo> {
+    let sema = Semantics::new(db);
+    let file = sema.parse(position.file_id);
+    let file = file.syntax();
+    let token = file.token_at_offset(position.offset).next()?;
+    let token = sema.descend_into_macros(token);
+
+    let (callable, active_parameter) = call_info_impl(&sema, token)?;
+
+    let mut res =
+        CallInfo { doc: None, signature: String::new(), parameters: vec![], active_parameter };
+
+    match callable.kind() {
+        hir::CallableKind::Function(func) => {
+            res.doc = func.docs(db).map(|it| it.as_str().to_string());
+            format_to!(res.signature, "fn {}", func.name(db));
+        }
+        hir::CallableKind::TupleStruct(strukt) => {
+            res.doc = strukt.docs(db).map(|it| it.as_str().to_string());
+            format_to!(res.signature, "struct {}", strukt.name(db));
+        }
+        hir::CallableKind::TupleEnumVariant(variant) => {
+            res.doc = variant.docs(db).map(|it| it.as_str().to_string());
+            format_to!(
+                res.signature,
+                "enum {}::{}",
+                variant.parent_enum(db).name(db),
+                variant.name(db)
+            );
+        }
+        hir::CallableKind::Closure => (),
+    }
+
+    res.signature.push('(');
+    {
+        if let Some(self_param) = callable.receiver_param(db) {
+            format_to!(res.signature, "{}", self_param)
+        }
+        let mut buf = String::new();
+        for (pat, ty) in callable.params(db) {
+            buf.clear();
+            if let Some(pat) = pat {
+                match pat {
+                    Either::Left(_self) => format_to!(buf, "self: "),
+                    Either::Right(pat) => format_to!(buf, "{}: ", pat),
+                }
+            }
+            format_to!(buf, "{}", ty.display(db));
+            res.push_param(&buf);
+        }
+    }
+    res.signature.push(')');
+
+    match callable.kind() {
+        hir::CallableKind::Function(_) | hir::CallableKind::Closure => {
+            let ret_type = callable.return_type();
+            if !ret_type.is_unit() {
+                format_to!(res.signature, " -> {}", ret_type.display(db));
+            }
+        }
+        hir::CallableKind::TupleStruct(_) | hir::CallableKind::TupleEnumVariant(_) => {}
+    }
+    Some(res)
+}
+
+fn call_info_impl(
+    sema: &Semantics<RootDatabase>,
+    token: SyntaxToken,
+) -> Option<(hir::Callable, Option<usize>)> {
+    // Find the calling expression and it's NameRef
+    let calling_node = FnCallNode::with_node(&token.parent())?;
+
+    let callable = match &calling_node {
+        FnCallNode::CallExpr(call) => sema.type_of_expr(&call.expr()?)?.as_callable(sema.db)?,
+        FnCallNode::MethodCallExpr(call) => sema.resolve_method_call_as_callable(call)?,
+    };
+    let active_param = if let Some(arg_list) = calling_node.arg_list() {
+        // Number of arguments specified at the call site
+        let num_args_at_callsite = arg_list.args().count();
+
+        let arg_list_range = arg_list.syntax().text_range();
+        if !arg_list_range.contains_inclusive(token.text_range().start()) {
+            mark::hit!(call_info_bad_offset);
+            return None;
+        }
+        let param = std::cmp::min(
+            num_args_at_callsite,
+            arg_list
+                .args()
+                .take_while(|arg| arg.syntax().text_range().end() <= token.text_range().start())
+                .count(),
+        );
+
+        Some(param)
+    } else {
+        None
+    };
+    Some((callable, active_param))
+}
+
+#[derive(Debug)]
+pub(crate) struct ActiveParameter {
+    pub(crate) ty: Type,
+    pub(crate) name: String,
+}
+
+impl ActiveParameter {
+    pub(crate) fn at(db: &RootDatabase, position: FilePosition) -> Option<Self> {
+        let sema = Semantics::new(db);
+        let file = sema.parse(position.file_id);
+        let file = file.syntax();
+        let token = file.token_at_offset(position.offset).next()?;
+        let token = sema.descend_into_macros(token);
+        Self::at_token(&sema, token)
+    }
+
+    pub(crate) fn at_token(sema: &Semantics<RootDatabase>, token: SyntaxToken) -> Option<Self> {
+        let (signature, active_parameter) = call_info_impl(&sema, token)?;
+
+        let idx = active_parameter?;
+        let mut params = signature.params(sema.db);
+        if !(idx < params.len()) {
+            mark::hit!(too_many_arguments);
+            return None;
+        }
+        let (pat, ty) = params.swap_remove(idx);
+        let name = pat?.to_string();
+        Some(ActiveParameter { ty, name })
+    }
+}
+
+#[derive(Debug)]
+pub(crate) enum FnCallNode {
+    CallExpr(ast::CallExpr),
+    MethodCallExpr(ast::MethodCallExpr),
+}
+
+impl FnCallNode {
+    fn with_node(syntax: &SyntaxNode) -> Option<FnCallNode> {
+        syntax.ancestors().find_map(|node| {
+            match_ast! {
+                match node {
+                    ast::CallExpr(it) => Some(FnCallNode::CallExpr(it)),
+                    ast::MethodCallExpr(it) => {
+                        let arg_list = it.arg_list()?;
+                        if !arg_list.syntax().text_range().contains_range(syntax.text_range()) {
+                            return None;
+                        }
+                        Some(FnCallNode::MethodCallExpr(it))
+                    },
+                    _ => None,
+                }
+            }
+        })
+    }
+
+    pub(crate) fn with_node_exact(node: &SyntaxNode) -> Option<FnCallNode> {
+        match_ast! {
+            match node {
+                ast::CallExpr(it) => Some(FnCallNode::CallExpr(it)),
+                ast::MethodCallExpr(it) => Some(FnCallNode::MethodCallExpr(it)),
+                _ => None,
+            }
+        }
+    }
+
+    pub(crate) fn name_ref(&self) -> Option<ast::NameRef> {
+        match self {
+            FnCallNode::CallExpr(call_expr) => Some(match call_expr.expr()? {
+                ast::Expr::PathExpr(path_expr) => path_expr.path()?.segment()?.name_ref()?,
+                _ => return None,
+            }),
+
+            FnCallNode::MethodCallExpr(call_expr) => {
+                call_expr.syntax().children().filter_map(ast::NameRef::cast).next()
+            }
+        }
+    }
+
+    fn arg_list(&self) -> Option<ast::ArgList> {
+        match self {
+            FnCallNode::CallExpr(expr) => expr.arg_list(),
+            FnCallNode::MethodCallExpr(expr) => expr.arg_list(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use test_utils::mark;
+
+    use crate::mock_analysis::analysis_and_position;
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let call_info = analysis.call_info(position).unwrap();
+        let actual = match call_info {
+            Some(call_info) => {
+                let docs = match &call_info.doc {
+                    None => "".to_string(),
+                    Some(docs) => format!("{}\n------\n", docs.as_str()),
+                };
+                let params = call_info
+                    .parameter_labels()
+                    .enumerate()
+                    .map(|(i, param)| {
+                        if Some(i) == call_info.active_parameter {
+                            format!("<{}>", param)
+                        } else {
+                            param.to_string()
+                        }
+                    })
+                    .collect::<Vec<_>>()
+                    .join(", ");
+                format!("{}{}\n({})\n", docs, call_info.signature, params)
+            }
+            None => String::new(),
+        };
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn test_fn_signature_two_args() {
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(<|>3, ); }
+"#,
+            expect![[r#"
+                fn foo(x: u32, y: u32) -> u32
+                (<x: u32>, y: u32)
+            "#]],
+        );
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(3<|>, ); }
+"#,
+            expect![[r#"
+                fn foo(x: u32, y: u32) -> u32
+                (<x: u32>, y: u32)
+            "#]],
+        );
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(3,<|> ); }
+"#,
+            expect![[r#"
+                fn foo(x: u32, y: u32) -> u32
+                (x: u32, <y: u32>)
+            "#]],
+        );
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(3, <|>); }
+"#,
+            expect![[r#"
+                fn foo(x: u32, y: u32) -> u32
+                (x: u32, <y: u32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_two_args_empty() {
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo(<|>); }
+"#,
+            expect![[r#"
+                fn foo(x: u32, y: u32) -> u32
+                (<x: u32>, y: u32)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_two_args_first_generics() {
+        check(
+            r#"
+fn foo<T, U: Copy + Display>(x: T, y: U) -> u32
+    where T: Copy + Display, U: Debug
+{ x + y }
+
+fn bar() { foo(<|>3, ); }
+"#,
+            expect![[r#"
+                fn foo(x: i32, y: {unknown}) -> u32
+                (<x: i32>, y: {unknown})
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_no_params() {
+        check(
+            r#"
+fn foo<T>() -> T where T: Copy + Display {}
+fn bar() { foo(<|>); }
+"#,
+            expect![[r#"
+                fn foo() -> {unknown}
+                ()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_for_impl() {
+        check(
+            r#"
+struct F;
+impl F { pub fn new() { } }
+fn bar() {
+    let _ : F = F::new(<|>);
+}
+"#,
+            expect![[r#"
+                fn new()
+                ()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_for_method_self() {
+        check(
+            r#"
+struct S;
+impl S { pub fn do_it(&self) {} }
+
+fn bar() {
+    let s: S = S;
+    s.do_it(<|>);
+}
+"#,
+            expect![[r#"
+                fn do_it(&self)
+                ()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_for_method_with_arg() {
+        check(
+            r#"
+struct S;
+impl S {
+    fn foo(&self, x: i32) {}
+}
+
+fn main() { S.foo(<|>); }
+"#,
+            expect![[r#"
+                fn foo(&self, x: i32)
+                (<x: i32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_for_method_with_arg_as_assoc_fn() {
+        check(
+            r#"
+struct S;
+impl S {
+    fn foo(&self, x: i32) {}
+}
+
+fn main() { S::foo(<|>); }
+"#,
+            expect![[r#"
+                fn foo(self: &S, x: i32)
+                (<self: &S>, x: i32)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_with_docs_simple() {
+        check(
+            r#"
+/// test
+// non-doc-comment
+fn foo(j: u32) -> u32 {
+    j
+}
+
+fn bar() {
+    let _ = foo(<|>);
+}
+"#,
+            expect![[r#"
+                test
+                ------
+                fn foo(j: u32) -> u32
+                (<j: u32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_with_docs() {
+        check(
+            r#"
+/// Adds one to the number given.
+///
+/// # Examples
+///
+/// ```
+/// let five = 5;
+///
+/// assert_eq!(6, my_crate::add_one(5));
+/// ```
+pub fn add_one(x: i32) -> i32 {
+    x + 1
+}
+
+pub fn do() {
+    add_one(<|>
+}"#,
+            expect![[r##"
+                Adds one to the number given.
+
+                # Examples
+
+                ```
+                let five = 5;
+
+                assert_eq!(6, my_crate::add_one(5));
+                ```
+                ------
+                fn add_one(x: i32) -> i32
+                (<x: i32>)
+            "##]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_with_docs_impl() {
+        check(
+            r#"
+struct addr;
+impl addr {
+    /// Adds one to the number given.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let five = 5;
+    ///
+    /// assert_eq!(6, my_crate::add_one(5));
+    /// ```
+    pub fn add_one(x: i32) -> i32 {
+        x + 1
+    }
+}
+
+pub fn do_it() {
+    addr {};
+    addr::add_one(<|>);
+}
+"#,
+            expect![[r##"
+                Adds one to the number given.
+
+                # Examples
+
+                ```
+                let five = 5;
+
+                assert_eq!(6, my_crate::add_one(5));
+                ```
+                ------
+                fn add_one(x: i32) -> i32
+                (<x: i32>)
+            "##]],
+        );
+    }
+
+    #[test]
+    fn test_fn_signature_with_docs_from_actix() {
+        check(
+            r#"
+struct WriteHandler<E>;
+
+impl<E> WriteHandler<E> {
+    /// Method is called when writer emits error.
+    ///
+    /// If this method returns `ErrorAction::Continue` writer processing
+    /// continues otherwise stream processing stops.
+    fn error(&mut self, err: E, ctx: &mut Self::Context) -> Running {
+        Running::Stop
+    }
+
+    /// Method is called when writer finishes.
+    ///
+    /// By default this method stops actor's `Context`.
+    fn finished(&mut self, ctx: &mut Self::Context) {
+        ctx.stop()
+    }
+}
+
+pub fn foo(mut r: WriteHandler<()>) {
+    r.finished(<|>);
+}
+"#,
+            expect![[r#"
+                Method is called when writer finishes.
+
+                By default this method stops actor's `Context`.
+                ------
+                fn finished(&mut self, ctx: &mut {unknown})
+                (<ctx: &mut {unknown}>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn call_info_bad_offset() {
+        mark::check!(call_info_bad_offset);
+        check(
+            r#"
+fn foo(x: u32, y: u32) -> u32 {x + y}
+fn bar() { foo <|> (3, ); }
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn test_nested_method_in_lambda() {
+        check(
+            r#"
+struct Foo;
+impl Foo { fn bar(&self, _: u32) { } }
+
+fn bar(_: u32) { }
+
+fn main() {
+    let foo = Foo;
+    std::thread::spawn(move || foo.bar(<|>));
+}
+"#,
+            expect![[r#"
+                fn bar(&self, _: u32)
+                (<_: u32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn works_for_tuple_structs() {
+        check(
+            r#"
+/// A cool tuple struct
+struct S(u32, i32);
+fn main() {
+    let s = S(0, <|>);
+}
+"#,
+            expect![[r#"
+                A cool tuple struct
+                ------
+                struct S(u32, i32)
+                (u32, <i32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn generic_struct() {
+        check(
+            r#"
+struct S<T>(T);
+fn main() {
+    let s = S(<|>);
+}
+"#,
+            expect![[r#"
+                struct S({unknown})
+                (<{unknown}>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn works_for_enum_variants() {
+        check(
+            r#"
+enum E {
+    /// A Variant
+    A(i32),
+    /// Another
+    B,
+    /// And C
+    C { a: i32, b: i32 }
+}
+
+fn main() {
+    let a = E::A(<|>);
+}
+"#,
+            expect![[r#"
+                A Variant
+                ------
+                enum E::A(i32)
+                (<i32>)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn cant_call_struct_record() {
+        check(
+            r#"
+struct S { x: u32, y: i32 }
+fn main() {
+    let s = S(<|>);
+}
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn cant_call_enum_record() {
+        check(
+            r#"
+enum E {
+    /// A Variant
+    A(i32),
+    /// Another
+    B,
+    /// And C
+    C { a: i32, b: i32 }
+}
+
+fn main() {
+    let a = E::C(<|>);
+}
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn fn_signature_for_call_in_macro() {
+        check(
+            r#"
+macro_rules! id { ($($tt:tt)*) => { $($tt)* } }
+fn foo() { }
+id! {
+    fn bar() { foo(<|>); }
+}
+"#,
+            expect![[r#"
+                fn foo()
+                ()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn call_info_for_lambdas() {
+        check(
+            r#"
+struct S;
+fn foo(s: S) -> i32 { 92 }
+fn main() {
+    (|s| foo(s))(<|>)
+}
+        "#,
+            expect![[r#"
+                (S) -> i32
+                (<S>)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn call_info_for_fn_ptr() {
+        check(
+            r#"
+fn main(f: fn(i32, f64) -> char) {
+    f(0, <|>)
+}
+        "#,
+            expect![[r#"
+                (i32, f64) -> char
+                (i32, <f64>)
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion.rs b/crates/ide/src/completion.rs
new file mode 100644
index 000000000..25e580d80
--- /dev/null
+++ b/crates/ide/src/completion.rs
@@ -0,0 +1,207 @@
+mod completion_config;
+mod completion_item;
+mod completion_context;
+mod presentation;
+mod patterns;
+mod generated_features;
+#[cfg(test)]
+mod test_utils;
+
+mod complete_attribute;
+mod complete_dot;
+mod complete_record;
+mod complete_pattern;
+mod complete_fn_param;
+mod complete_keyword;
+mod complete_snippet;
+mod complete_qualified_path;
+mod complete_unqualified_path;
+mod complete_postfix;
+mod complete_macro_in_item_position;
+mod complete_trait_impl;
+
+use ide_db::RootDatabase;
+
+use crate::{
+    completion::{
+        completion_context::CompletionContext,
+        completion_item::{CompletionKind, Completions},
+    },
+    FilePosition,
+};
+
+pub use crate::completion::{
+    completion_config::CompletionConfig,
+    completion_item::{CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat},
+};
+
+//FIXME: split the following feature into fine-grained features.
+
+// Feature: Magic Completions
+//
+// In addition to usual reference completion, rust-analyzer provides some ✨magic✨
+// completions as well:
+//
+// Keywords like `if`, `else` `while`, `loop` are completed with braces, and cursor
+// is placed at the appropriate position. Even though `if` is easy to type, you
+// still want to complete it, to get ` { }` for free! `return` is inserted with a
+// space or `;` depending on the return type of the function.
+//
+// When completing a function call, `()` are automatically inserted. If a function
+// takes arguments, the cursor is positioned inside the parenthesis.
+//
+// There are postfix completions, which can be triggered by typing something like
+// `foo().if`. The word after `.` determines postfix completion. Possible variants are:
+//
+// - `expr.if` -> `if expr {}` or `if let ... {}` for `Option` or `Result`
+// - `expr.match` -> `match expr {}`
+// - `expr.while` -> `while expr {}` or `while let ... {}` for `Option` or `Result`
+// - `expr.ref` -> `&expr`
+// - `expr.refm` -> `&mut expr`
+// - `expr.not` -> `!expr`
+// - `expr.dbg` -> `dbg!(expr)`
+//
+// There also snippet completions:
+//
+// .Expressions
+// - `pd` -> `eprintln!(" = {:?}", );`
+// - `ppd` -> `eprintln!(" = {:#?}", );`
+//
+// .Items
+// - `tfn` -> `#[test] fn feature(){}`
+// - `tmod` ->
+// ```rust
+// #[cfg(test)]
+// mod tests {
+//     use super::*;
+//
+//     #[test]
+//     fn test_name() {}
+// }
+// ```
+
+/// Main entry point for completion. We run completion as a two-phase process.
+///
+/// First, we look at the position and collect a so-called `CompletionContext.
+/// This is a somewhat messy process, because, during completion, syntax tree is
+/// incomplete and can look really weird.
+///
+/// Once the context is collected, we run a series of completion routines which
+/// look at the context and produce completion items. One subtlety about this
+/// phase is that completion engine should not filter by the substring which is
+/// already present, it should give all possible variants for the identifier at
+/// the caret. In other words, for
+///
+/// ```no-run
+/// fn f() {
+///     let foo = 92;
+///     let _ = bar<|>
+/// }
+/// ```
+///
+/// `foo` *should* be present among the completion variants. Filtering by
+/// identifier prefix/fuzzy match should be done higher in the stack, together
+/// with ordering of completions (currently this is done by the client).
+pub(crate) fn completions(
+    db: &RootDatabase,
+    config: &CompletionConfig,
+    position: FilePosition,
+) -> Option<Completions> {
+    let ctx = CompletionContext::new(db, position, config)?;
+
+    let mut acc = Completions::default();
+    complete_attribute::complete_attribute(&mut acc, &ctx);
+    complete_fn_param::complete_fn_param(&mut acc, &ctx);
+    complete_keyword::complete_expr_keyword(&mut acc, &ctx);
+    complete_keyword::complete_use_tree_keyword(&mut acc, &ctx);
+    complete_snippet::complete_expr_snippet(&mut acc, &ctx);
+    complete_snippet::complete_item_snippet(&mut acc, &ctx);
+    complete_qualified_path::complete_qualified_path(&mut acc, &ctx);
+    complete_unqualified_path::complete_unqualified_path(&mut acc, &ctx);
+    complete_dot::complete_dot(&mut acc, &ctx);
+    complete_record::complete_record(&mut acc, &ctx);
+    complete_pattern::complete_pattern(&mut acc, &ctx);
+    complete_postfix::complete_postfix(&mut acc, &ctx);
+    complete_macro_in_item_position::complete_macro_in_item_position(&mut acc, &ctx);
+    complete_trait_impl::complete_trait_impl(&mut acc, &ctx);
+
+    Some(acc)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::completion::completion_config::CompletionConfig;
+    use crate::mock_analysis::analysis_and_position;
+
+    struct DetailAndDocumentation<'a> {
+        detail: &'a str,
+        documentation: &'a str,
+    }
+
+    fn check_detail_and_documentation(ra_fixture: &str, expected: DetailAndDocumentation) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let config = CompletionConfig::default();
+        let completions = analysis.completions(&config, position).unwrap().unwrap();
+        for item in completions {
+            if item.detail() == Some(expected.detail) {
+                let opt = item.documentation();
+                let doc = opt.as_ref().map(|it| it.as_str());
+                assert_eq!(doc, Some(expected.documentation));
+                return;
+            }
+        }
+        panic!("completion detail not found: {}", expected.detail)
+    }
+
+    #[test]
+    fn test_completion_detail_from_macro_generated_struct_fn_doc_attr() {
+        check_detail_and_documentation(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        #[doc = "Do the foo"]
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>;
+            }
+            "#,
+            DetailAndDocumentation { detail: "fn foo(&self)", documentation: "Do the foo" },
+        );
+    }
+
+    #[test]
+    fn test_completion_detail_from_macro_generated_struct_fn_doc_comment() {
+        check_detail_and_documentation(
+            r#"
+            //- /lib.rs
+            macro_rules! bar {
+                () => {
+                    struct Bar;
+                    impl Bar {
+                        /// Do the foo
+                        fn foo(&self) {}
+                    }
+                }
+            }
+
+            bar!();
+
+            fn foo() {
+                let bar = Bar;
+                bar.fo<|>;
+            }
+            "#,
+            DetailAndDocumentation { detail: "fn foo(&self)", documentation: " Do the foo" },
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_attribute.rs b/crates/ide/src/completion/complete_attribute.rs
new file mode 100644
index 000000000..0abfaebcb
--- /dev/null
+++ b/crates/ide/src/completion/complete_attribute.rs
@@ -0,0 +1,653 @@
+//! Completion for attributes
+//!
+//! This module uses a bit of static metadata to provide completions
+//! for built-in attributes.
+
+use rustc_hash::FxHashSet;
+use syntax::{ast, AstNode, SyntaxKind};
+
+use crate::completion::{
+    completion_context::CompletionContext,
+    completion_item::{CompletionItem, CompletionItemKind, CompletionKind, Completions},
+    generated_features::FEATURES,
+};
+
+pub(super) fn complete_attribute(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
+    let attribute = ctx.attribute_under_caret.as_ref()?;
+    match (attribute.path(), attribute.token_tree()) {
+        (Some(path), Some(token_tree)) if path.to_string() == "derive" => {
+            complete_derive(acc, ctx, token_tree)
+        }
+        (Some(path), Some(token_tree)) if path.to_string() == "feature" => {
+            complete_lint(acc, ctx, token_tree, FEATURES)
+        }
+        (Some(path), Some(token_tree))
+            if ["allow", "warn", "deny", "forbid"]
+                .iter()
+                .any(|lint_level| lint_level == &path.to_string()) =>
+        {
+            complete_lint(acc, ctx, token_tree, DEFAULT_LINT_COMPLETIONS)
+        }
+        (_, Some(_token_tree)) => {}
+        _ => complete_attribute_start(acc, ctx, attribute),
+    }
+    Some(())
+}
+
+fn complete_attribute_start(acc: &mut Completions, ctx: &CompletionContext, attribute: &ast::Attr) {
+    for attr_completion in ATTRIBUTES {
+        let mut item = CompletionItem::new(
+            CompletionKind::Attribute,
+            ctx.source_range(),
+            attr_completion.label,
+        )
+        .kind(CompletionItemKind::Attribute);
+
+        if let Some(lookup) = attr_completion.lookup {
+            item = item.lookup_by(lookup);
+        }
+
+        match (attr_completion.snippet, ctx.config.snippet_cap) {
+            (Some(snippet), Some(cap)) => {
+                item = item.insert_snippet(cap, snippet);
+            }
+            _ => {}
+        }
+
+        if attribute.kind() == ast::AttrKind::Inner || !attr_completion.prefer_inner {
+            acc.add(item);
+        }
+    }
+}
+
+struct AttrCompletion {
+    label: &'static str,
+    lookup: Option<&'static str>,
+    snippet: Option<&'static str>,
+    prefer_inner: bool,
+}
+
+impl AttrCompletion {
+    const fn prefer_inner(self) -> AttrCompletion {
+        AttrCompletion { prefer_inner: true, ..self }
+    }
+}
+
+const fn attr(
+    label: &'static str,
+    lookup: Option<&'static str>,
+    snippet: Option<&'static str>,
+) -> AttrCompletion {
+    AttrCompletion { label, lookup, snippet, prefer_inner: false }
+}
+
+const ATTRIBUTES: &[AttrCompletion] = &[
+    attr("allow(…)", Some("allow"), Some("allow(${0:lint})")),
+    attr("cfg_attr(…)", Some("cfg_attr"), Some("cfg_attr(${1:predicate}, ${0:attr})")),
+    attr("cfg(…)", Some("cfg"), Some("cfg(${0:predicate})")),
+    attr("deny(…)", Some("deny"), Some("deny(${0:lint})")),
+    attr(r#"deprecated = "…""#, Some("deprecated"), Some(r#"deprecated = "${0:reason}""#)),
+    attr("derive(…)", Some("derive"), Some(r#"derive(${0:Debug})"#)),
+    attr(r#"doc = "…""#, Some("doc"), Some(r#"doc = "${0:docs}""#)),
+    attr("feature(…)", Some("feature"), Some("feature(${0:flag})")).prefer_inner(),
+    attr("forbid(…)", Some("forbid"), Some("forbid(${0:lint})")),
+    // FIXME: resolve through macro resolution?
+    attr("global_allocator", None, None).prefer_inner(),
+    attr(r#"ignore = "…""#, Some("ignore"), Some(r#"ignore = "${0:reason}""#)),
+    attr("inline(…)", Some("inline"), Some("inline(${0:lint})")),
+    attr(r#"link_name = "…""#, Some("link_name"), Some(r#"link_name = "${0:symbol_name}""#)),
+    attr("link", None, None),
+    attr("macro_export", None, None),
+    attr("macro_use", None, None),
+    attr(r#"must_use = "…""#, Some("must_use"), Some(r#"must_use = "${0:reason}""#)),
+    attr("no_mangle", None, None),
+    attr("no_std", None, None).prefer_inner(),
+    attr("non_exhaustive", None, None),
+    attr("panic_handler", None, None).prefer_inner(),
+    attr("path = \"…\"", Some("path"), Some("path =\"${0:path}\"")),
+    attr("proc_macro", None, None),
+    attr("proc_macro_attribute", None, None),
+    attr("proc_macro_derive(…)", Some("proc_macro_derive"), Some("proc_macro_derive(${0:Trait})")),
+    attr("recursion_limit = …", Some("recursion_limit"), Some("recursion_limit = ${0:128}"))
+        .prefer_inner(),
+    attr("repr(…)", Some("repr"), Some("repr(${0:C})")),
+    attr(
+        "should_panic(…)",
+        Some("should_panic"),
+        Some(r#"should_panic(expected = "${0:reason}")"#),
+    ),
+    attr(
+        r#"target_feature = "…""#,
+        Some("target_feature"),
+        Some("target_feature = \"${0:feature}\""),
+    ),
+    attr("test", None, None),
+    attr("used", None, None),
+    attr("warn(…)", Some("warn"), Some("warn(${0:lint})")),
+    attr(
+        r#"windows_subsystem = "…""#,
+        Some("windows_subsystem"),
+        Some(r#"windows_subsystem = "${0:subsystem}""#),
+    )
+    .prefer_inner(),
+];
+
+fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, derive_input: ast::TokenTree) {
+    if let Ok(existing_derives) = parse_comma_sep_input(derive_input) {
+        for derive_completion in DEFAULT_DERIVE_COMPLETIONS
+            .into_iter()
+            .filter(|completion| !existing_derives.contains(completion.label))
+        {
+            let mut label = derive_completion.label.to_owned();
+            for dependency in derive_completion
+                .dependencies
+                .into_iter()
+                .filter(|&&dependency| !existing_derives.contains(dependency))
+            {
+                label.push_str(", ");
+                label.push_str(dependency);
+            }
+            acc.add(
+                CompletionItem::new(CompletionKind::Attribute, ctx.source_range(), label)
+                    .kind(CompletionItemKind::Attribute),
+            );
+        }
+
+        for custom_derive_name in get_derive_names_in_scope(ctx).difference(&existing_derives) {
+            acc.add(
+                CompletionItem::new(
+                    CompletionKind::Attribute,
+                    ctx.source_range(),
+                    custom_derive_name,
+                )
+                .kind(CompletionItemKind::Attribute),
+            );
+        }
+    }
+}
+
+fn complete_lint(
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    derive_input: ast::TokenTree,
+    lints_completions: &[LintCompletion],
+) {
+    if let Ok(existing_lints) = parse_comma_sep_input(derive_input) {
+        for lint_completion in lints_completions
+            .into_iter()
+            .filter(|completion| !existing_lints.contains(completion.label))
+        {
+            acc.add(
+                CompletionItem::new(
+                    CompletionKind::Attribute,
+                    ctx.source_range(),
+                    lint_completion.label,
+                )
+                .kind(CompletionItemKind::Attribute)
+                .detail(lint_completion.description),
+            );
+        }
+    }
+}
+
+fn parse_comma_sep_input(derive_input: ast::TokenTree) -> Result<FxHashSet<String>, ()> {
+    match (derive_input.left_delimiter_token(), derive_input.right_delimiter_token()) {
+        (Some(left_paren), Some(right_paren))
+            if left_paren.kind() == SyntaxKind::L_PAREN
+                && right_paren.kind() == SyntaxKind::R_PAREN =>
+        {
+            let mut input_derives = FxHashSet::default();
+            let mut current_derive = String::new();
+            for token in derive_input
+                .syntax()
+                .children_with_tokens()
+                .filter_map(|token| token.into_token())
+                .skip_while(|token| token != &left_paren)
+                .skip(1)
+                .take_while(|token| token != &right_paren)
+            {
+                if SyntaxKind::COMMA == token.kind() {
+                    if !current_derive.is_empty() {
+                        input_derives.insert(current_derive);
+                        current_derive = String::new();
+                    }
+                } else {
+                    current_derive.push_str(token.to_string().trim());
+                }
+            }
+
+            if !current_derive.is_empty() {
+                input_derives.insert(current_derive);
+            }
+            Ok(input_derives)
+        }
+        _ => Err(()),
+    }
+}
+
+fn get_derive_names_in_scope(ctx: &CompletionContext) -> FxHashSet<String> {
+    let mut result = FxHashSet::default();
+    ctx.scope.process_all_names(&mut |name, scope_def| {
+        if let hir::ScopeDef::MacroDef(mac) = scope_def {
+            if mac.is_derive_macro() {
+                result.insert(name.to_string());
+            }
+        }
+    });
+    result
+}
+
+struct DeriveCompletion {
+    label: &'static str,
+    dependencies: &'static [&'static str],
+}
+
+/// Standard Rust derives and the information about their dependencies
+/// (the dependencies are needed so that the main derive don't break the compilation when added)
+#[rustfmt::skip]
+const DEFAULT_DERIVE_COMPLETIONS: &[DeriveCompletion] = &[
+    DeriveCompletion { label: "Clone", dependencies: &[] },
+    DeriveCompletion { label: "Copy", dependencies: &["Clone"] },
+    DeriveCompletion { label: "Debug", dependencies: &[] },
+    DeriveCompletion { label: "Default", dependencies: &[] },
+    DeriveCompletion { label: "Hash", dependencies: &[] },
+    DeriveCompletion { label: "PartialEq", dependencies: &[] },
+    DeriveCompletion { label: "Eq", dependencies: &["PartialEq"] },
+    DeriveCompletion { label: "PartialOrd", dependencies: &["PartialEq"] },
+    DeriveCompletion { label: "Ord", dependencies: &["PartialOrd", "Eq", "PartialEq"] },
+];
+
+pub(super) struct LintCompletion {
+    pub(super) label: &'static str,
+    pub(super) description: &'static str,
+}
+
+#[rustfmt::skip]
+const DEFAULT_LINT_COMPLETIONS: &[LintCompletion] = &[
+    LintCompletion { label: "absolute_paths_not_starting_with_crate", description: r#"fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name"# },
+    LintCompletion { label: "anonymous_parameters", description: r#"detects anonymous parameters"# },
+    LintCompletion { label: "box_pointers", description: r#"use of owned (Box type) heap memory"# },
+    LintCompletion { label: "deprecated_in_future", description: r#"detects use of items that will be deprecated in a future version"# },
+    LintCompletion { label: "elided_lifetimes_in_paths", description: r#"hidden lifetime parameters in types are deprecated"# },
+    LintCompletion { label: "explicit_outlives_requirements", description: r#"outlives requirements can be inferred"# },
+    LintCompletion { label: "indirect_structural_match", description: r#"pattern with const indirectly referencing non-structural-match type"# },
+    LintCompletion { label: "keyword_idents", description: r#"detects edition keywords being used as an identifier"# },
+    LintCompletion { label: "macro_use_extern_crate", description: r#"the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system"# },
+    LintCompletion { label: "meta_variable_misuse", description: r#"possible meta-variable misuse at macro definition"# },
+    LintCompletion { label: "missing_copy_implementations", description: r#"detects potentially-forgotten implementations of `Copy`"# },
+    LintCompletion { label: "missing_crate_level_docs", description: r#"detects crates with no crate-level documentation"# },
+    LintCompletion { label: "missing_debug_implementations", description: r#"detects missing implementations of Debug"# },
+    LintCompletion { label: "missing_docs", description: r#"detects missing documentation for public members"# },
+    LintCompletion { label: "missing_doc_code_examples", description: r#"detects publicly-exported items without code samples in their documentation"# },
+    LintCompletion { label: "non_ascii_idents", description: r#"detects non-ASCII identifiers"# },
+    LintCompletion { label: "private_doc_tests", description: r#"detects code samples in docs of private items not documented by rustdoc"# },
+    LintCompletion { label: "single_use_lifetimes", description: r#"detects lifetime parameters that are only used once"# },
+    LintCompletion { label: "trivial_casts", description: r#"detects trivial casts which could be removed"# },
+    LintCompletion { label: "trivial_numeric_casts", description: r#"detects trivial casts of numeric types which could be removed"# },
+    LintCompletion { label: "unaligned_references", description: r#"detects unaligned references to fields of packed structs"# },
+    LintCompletion { label: "unreachable_pub", description: r#"`pub` items not reachable from crate root"# },
+    LintCompletion { label: "unsafe_code", description: r#"usage of `unsafe` code"# },
+    LintCompletion { label: "unsafe_op_in_unsafe_fn", description: r#"unsafe operations in unsafe functions without an explicit unsafe block are deprecated"# },
+    LintCompletion { label: "unstable_features", description: r#"enabling unstable features (deprecated. do not use)"# },
+    LintCompletion { label: "unused_crate_dependencies", description: r#"crate dependencies that are never used"# },
+    LintCompletion { label: "unused_extern_crates", description: r#"extern crates that are never used"# },
+    LintCompletion { label: "unused_import_braces", description: r#"unnecessary braces around an imported item"# },
+    LintCompletion { label: "unused_lifetimes", description: r#"detects lifetime parameters that are never used"# },
+    LintCompletion { label: "unused_qualifications", description: r#"detects unnecessarily qualified names"# },
+    LintCompletion { label: "unused_results", description: r#"unused result of an expression in a statement"# },
+    LintCompletion { label: "variant_size_differences", description: r#"detects enums with widely varying variant sizes"# },
+    LintCompletion { label: "array_into_iter", description: r#"detects calling `into_iter` on arrays"# },
+    LintCompletion { label: "asm_sub_register", description: r#"using only a subset of a register for inline asm inputs"# },
+    LintCompletion { label: "bare_trait_objects", description: r#"suggest using `dyn Trait` for trait objects"# },
+    LintCompletion { label: "bindings_with_variant_name", description: r#"detects pattern bindings with the same name as one of the matched variants"# },
+    LintCompletion { label: "cenum_impl_drop_cast", description: r#"a C-like enum implementing Drop is cast"# },
+    LintCompletion { label: "clashing_extern_declarations", description: r#"detects when an extern fn has been declared with the same name but different types"# },
+    LintCompletion { label: "coherence_leak_check", description: r#"distinct impls distinguished only by the leak-check code"# },
+    LintCompletion { label: "confusable_idents", description: r#"detects visually confusable pairs between identifiers"# },
+    LintCompletion { label: "dead_code", description: r#"detect unused, unexported items"# },
+    LintCompletion { label: "deprecated", description: r#"detects use of deprecated items"# },
+    LintCompletion { label: "ellipsis_inclusive_range_patterns", description: r#"`...` range patterns are deprecated"# },
+    LintCompletion { label: "exported_private_dependencies", description: r#"public interface leaks type from a private dependency"# },
+    LintCompletion { label: "illegal_floating_point_literal_pattern", description: r#"floating-point literals cannot be used in patterns"# },
+    LintCompletion { label: "improper_ctypes", description: r#"proper use of libc types in foreign modules"# },
+    LintCompletion { label: "improper_ctypes_definitions", description: r#"proper use of libc types in foreign item definitions"# },
+    LintCompletion { label: "incomplete_features", description: r#"incomplete features that may function improperly in some or all cases"# },
+    LintCompletion { label: "inline_no_sanitize", description: r#"detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`"# },
+    LintCompletion { label: "intra_doc_link_resolution_failure", description: r#"failures in resolving intra-doc link targets"# },
+    LintCompletion { label: "invalid_codeblock_attributes", description: r#"codeblock attribute looks a lot like a known one"# },
+    LintCompletion { label: "invalid_value", description: r#"an invalid value is being created (such as a NULL reference)"# },
+    LintCompletion { label: "irrefutable_let_patterns", description: r#"detects irrefutable patterns in if-let and while-let statements"# },
+    LintCompletion { label: "late_bound_lifetime_arguments", description: r#"detects generic lifetime arguments in path segments with late bound lifetime parameters"# },
+    LintCompletion { label: "mixed_script_confusables", description: r#"detects Unicode scripts whose mixed script confusables codepoints are solely used"# },
+    LintCompletion { label: "mutable_borrow_reservation_conflict", description: r#"reservation of a two-phased borrow conflicts with other shared borrows"# },
+    LintCompletion { label: "non_camel_case_types", description: r#"types, variants, traits and type parameters should have camel case names"# },
+    LintCompletion { label: "non_shorthand_field_patterns", description: r#"using `Struct { x: x }` instead of `Struct { x }` in a pattern"# },
+    LintCompletion { label: "non_snake_case", description: r#"variables, methods, functions, lifetime parameters and modules should have snake case names"# },
+    LintCompletion { label: "non_upper_case_globals", description: r#"static constants should have uppercase identifiers"# },
+    LintCompletion { label: "no_mangle_generic_items", description: r#"generic items must be mangled"# },
+    LintCompletion { label: "overlapping_patterns", description: r#"detects overlapping patterns"# },
+    LintCompletion { label: "path_statements", description: r#"path statements with no effect"# },
+    LintCompletion { label: "private_in_public", description: r#"detect private items in public interfaces not caught by the old implementation"# },
+    LintCompletion { label: "proc_macro_derive_resolution_fallback", description: r#"detects proc macro derives using inaccessible names from parent modules"# },
+    LintCompletion { label: "redundant_semicolons", description: r#"detects unnecessary trailing semicolons"# },
+    LintCompletion { label: "renamed_and_removed_lints", description: r#"lints that have been renamed or removed"# },
+    LintCompletion { label: "safe_packed_borrows", description: r#"safe borrows of fields of packed structs were erroneously allowed"# },
+    LintCompletion { label: "stable_features", description: r#"stable features found in `#[feature]` directive"# },
+    LintCompletion { label: "trivial_bounds", description: r#"these bounds don't depend on an type parameters"# },
+    LintCompletion { label: "type_alias_bounds", description: r#"bounds in type aliases are not enforced"# },
+    LintCompletion { label: "tyvar_behind_raw_pointer", description: r#"raw pointer to an inference variable"# },
+    LintCompletion { label: "uncommon_codepoints", description: r#"detects uncommon Unicode codepoints in identifiers"# },
+    LintCompletion { label: "unconditional_recursion", description: r#"functions that cannot return without calling themselves"# },
+    LintCompletion { label: "unknown_lints", description: r#"unrecognized lint attribute"# },
+    LintCompletion { label: "unnameable_test_items", description: r#"detects an item that cannot be named being marked as `#[test_case]`"# },
+    LintCompletion { label: "unreachable_code", description: r#"detects unreachable code paths"# },
+    LintCompletion { label: "unreachable_patterns", description: r#"detects unreachable patterns"# },
+    LintCompletion { label: "unstable_name_collisions", description: r#"detects name collision with an existing but unstable method"# },
+    LintCompletion { label: "unused_allocation", description: r#"detects unnecessary allocations that can be eliminated"# },
+    LintCompletion { label: "unused_assignments", description: r#"detect assignments that will never be read"# },
+    LintCompletion { label: "unused_attributes", description: r#"detects attributes that were not used by the compiler"# },
+    LintCompletion { label: "unused_braces", description: r#"unnecessary braces around an expression"# },
+    LintCompletion { label: "unused_comparisons", description: r#"comparisons made useless by limits of the types involved"# },
+    LintCompletion { label: "unused_doc_comments", description: r#"detects doc comments that aren't used by rustdoc"# },
+    LintCompletion { label: "unused_features", description: r#"unused features found in crate-level `#[feature]` directives"# },
+    LintCompletion { label: "unused_imports", description: r#"imports that are never used"# },
+    LintCompletion { label: "unused_labels", description: r#"detects labels that are never used"# },
+    LintCompletion { label: "unused_macros", description: r#"detects macros that were not used"# },
+    LintCompletion { label: "unused_must_use", description: r#"unused result of a type flagged as `#[must_use]`"# },
+    LintCompletion { label: "unused_mut", description: r#"detect mut variables which don't need to be mutable"# },
+    LintCompletion { label: "unused_parens", description: r#"`if`, `match`, `while` and `return` do not need parentheses"# },
+    LintCompletion { label: "unused_unsafe", description: r#"unnecessary use of an `unsafe` block"# },
+    LintCompletion { label: "unused_variables", description: r#"detect variables which are not used in any way"# },
+    LintCompletion { label: "warnings", description: r#"mass-change the level for lints which produce warnings"# },
+    LintCompletion { label: "where_clauses_object_safety", description: r#"checks the object safety of where clauses"# },
+    LintCompletion { label: "while_true", description: r#"suggest using `loop { }` instead of `while true { }`"# },
+    LintCompletion { label: "ambiguous_associated_items", description: r#"ambiguous associated items"# },
+    LintCompletion { label: "arithmetic_overflow", description: r#"arithmetic operation overflows"# },
+    LintCompletion { label: "conflicting_repr_hints", description: r#"conflicts between `#[repr(..)]` hints that were previously accepted and used in practice"# },
+    LintCompletion { label: "const_err", description: r#"constant evaluation detected erroneous expression"# },
+    LintCompletion { label: "ill_formed_attribute_input", description: r#"ill-formed attribute inputs that were previously accepted and used in practice"# },
+    LintCompletion { label: "incomplete_include", description: r#"trailing content in included file"# },
+    LintCompletion { label: "invalid_type_param_default", description: r#"type parameter default erroneously allowed in invalid location"# },
+    LintCompletion { label: "macro_expanded_macro_exports_accessed_by_absolute_paths", description: r#"macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths"# },
+    LintCompletion { label: "missing_fragment_specifier", description: r#"detects missing fragment specifiers in unused `macro_rules!` patterns"# },
+    LintCompletion { label: "mutable_transmutes", description: r#"mutating transmuted &mut T from &T may cause undefined behavior"# },
+    LintCompletion { label: "no_mangle_const_items", description: r#"const items will not have their symbols exported"# },
+    LintCompletion { label: "order_dependent_trait_objects", description: r#"trait-object types were treated as different depending on marker-trait order"# },
+    LintCompletion { label: "overflowing_literals", description: r#"literal out of range for its type"# },
+    LintCompletion { label: "patterns_in_fns_without_body", description: r#"patterns in functions without body were erroneously allowed"# },
+    LintCompletion { label: "pub_use_of_private_extern_crate", description: r#"detect public re-exports of private extern crates"# },
+    LintCompletion { label: "soft_unstable", description: r#"a feature gate that doesn't break dependent crates"# },
+    LintCompletion { label: "unconditional_panic", description: r#"operation will cause a panic at runtime"# },
+    LintCompletion { label: "unknown_crate_types", description: r#"unknown crate type found in `#[crate_type]` directive"# },
+];
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Attribute);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn empty_derive_completion() {
+        check(
+            r#"
+#[derive(<|>)]
+struct Test {}
+        "#,
+            expect![[r#"
+                at Clone
+                at Copy, Clone
+                at Debug
+                at Default
+                at Eq, PartialEq
+                at Hash
+                at Ord, PartialOrd, Eq, PartialEq
+                at PartialEq
+                at PartialOrd, PartialEq
+            "#]],
+        );
+    }
+
+    #[test]
+    fn empty_lint_completion() {
+        check(
+            r#"#[allow(<|>)]"#,
+            expect![[r#"
+                at absolute_paths_not_starting_with_crate fully qualified paths that start with a module name instead of `crate`, `self`, or an extern crate name
+                at ambiguous_associated_items ambiguous associated items
+                at anonymous_parameters detects anonymous parameters
+                at arithmetic_overflow arithmetic operation overflows
+                at array_into_iter  detects calling `into_iter` on arrays
+                at asm_sub_register using only a subset of a register for inline asm inputs
+                at bare_trait_objects suggest using `dyn Trait` for trait objects
+                at bindings_with_variant_name detects pattern bindings with the same name as one of the matched variants
+                at box_pointers     use of owned (Box type) heap memory
+                at cenum_impl_drop_cast a C-like enum implementing Drop is cast
+                at clashing_extern_declarations detects when an extern fn has been declared with the same name but different types
+                at coherence_leak_check distinct impls distinguished only by the leak-check code
+                at conflicting_repr_hints conflicts between `#[repr(..)]` hints that were previously accepted and used in practice
+                at confusable_idents detects visually confusable pairs between identifiers
+                at const_err        constant evaluation detected erroneous expression
+                at dead_code        detect unused, unexported items
+                at deprecated       detects use of deprecated items
+                at deprecated_in_future detects use of items that will be deprecated in a future version
+                at elided_lifetimes_in_paths hidden lifetime parameters in types are deprecated
+                at ellipsis_inclusive_range_patterns `...` range patterns are deprecated
+                at explicit_outlives_requirements outlives requirements can be inferred
+                at exported_private_dependencies public interface leaks type from a private dependency
+                at ill_formed_attribute_input ill-formed attribute inputs that were previously accepted and used in practice
+                at illegal_floating_point_literal_pattern floating-point literals cannot be used in patterns
+                at improper_ctypes  proper use of libc types in foreign modules
+                at improper_ctypes_definitions proper use of libc types in foreign item definitions
+                at incomplete_features incomplete features that may function improperly in some or all cases
+                at incomplete_include trailing content in included file
+                at indirect_structural_match pattern with const indirectly referencing non-structural-match type
+                at inline_no_sanitize detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`
+                at intra_doc_link_resolution_failure failures in resolving intra-doc link targets
+                at invalid_codeblock_attributes codeblock attribute looks a lot like a known one
+                at invalid_type_param_default type parameter default erroneously allowed in invalid location
+                at invalid_value    an invalid value is being created (such as a NULL reference)
+                at irrefutable_let_patterns detects irrefutable patterns in if-let and while-let statements
+                at keyword_idents   detects edition keywords being used as an identifier
+                at late_bound_lifetime_arguments detects generic lifetime arguments in path segments with late bound lifetime parameters
+                at macro_expanded_macro_exports_accessed_by_absolute_paths macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths
+                at macro_use_extern_crate the `#[macro_use]` attribute is now deprecated in favor of using macros via the module system
+                at meta_variable_misuse possible meta-variable misuse at macro definition
+                at missing_copy_implementations detects potentially-forgotten implementations of `Copy`
+                at missing_crate_level_docs detects crates with no crate-level documentation
+                at missing_debug_implementations detects missing implementations of Debug
+                at missing_doc_code_examples detects publicly-exported items without code samples in their documentation
+                at missing_docs     detects missing documentation for public members
+                at missing_fragment_specifier detects missing fragment specifiers in unused `macro_rules!` patterns
+                at mixed_script_confusables detects Unicode scripts whose mixed script confusables codepoints are solely used
+                at mutable_borrow_reservation_conflict reservation of a two-phased borrow conflicts with other shared borrows
+                at mutable_transmutes mutating transmuted &mut T from &T may cause undefined behavior
+                at no_mangle_const_items const items will not have their symbols exported
+                at no_mangle_generic_items generic items must be mangled
+                at non_ascii_idents detects non-ASCII identifiers
+                at non_camel_case_types types, variants, traits and type parameters should have camel case names
+                at non_shorthand_field_patterns using `Struct { x: x }` instead of `Struct { x }` in a pattern
+                at non_snake_case   variables, methods, functions, lifetime parameters and modules should have snake case names
+                at non_upper_case_globals static constants should have uppercase identifiers
+                at order_dependent_trait_objects trait-object types were treated as different depending on marker-trait order
+                at overflowing_literals literal out of range for its type
+                at overlapping_patterns detects overlapping patterns
+                at path_statements  path statements with no effect
+                at patterns_in_fns_without_body patterns in functions without body were erroneously allowed
+                at private_doc_tests detects code samples in docs of private items not documented by rustdoc
+                at private_in_public detect private items in public interfaces not caught by the old implementation
+                at proc_macro_derive_resolution_fallback detects proc macro derives using inaccessible names from parent modules
+                at pub_use_of_private_extern_crate detect public re-exports of private extern crates
+                at redundant_semicolons detects unnecessary trailing semicolons
+                at renamed_and_removed_lints lints that have been renamed or removed
+                at safe_packed_borrows safe borrows of fields of packed structs were erroneously allowed
+                at single_use_lifetimes detects lifetime parameters that are only used once
+                at soft_unstable    a feature gate that doesn't break dependent crates
+                at stable_features  stable features found in `#[feature]` directive
+                at trivial_bounds   these bounds don't depend on an type parameters
+                at trivial_casts    detects trivial casts which could be removed
+                at trivial_numeric_casts detects trivial casts of numeric types which could be removed
+                at type_alias_bounds bounds in type aliases are not enforced
+                at tyvar_behind_raw_pointer raw pointer to an inference variable
+                at unaligned_references detects unaligned references to fields of packed structs
+                at uncommon_codepoints detects uncommon Unicode codepoints in identifiers
+                at unconditional_panic operation will cause a panic at runtime
+                at unconditional_recursion functions that cannot return without calling themselves
+                at unknown_crate_types unknown crate type found in `#[crate_type]` directive
+                at unknown_lints    unrecognized lint attribute
+                at unnameable_test_items detects an item that cannot be named being marked as `#[test_case]`
+                at unreachable_code detects unreachable code paths
+                at unreachable_patterns detects unreachable patterns
+                at unreachable_pub  `pub` items not reachable from crate root
+                at unsafe_code      usage of `unsafe` code
+                at unsafe_op_in_unsafe_fn unsafe operations in unsafe functions without an explicit unsafe block are deprecated
+                at unstable_features enabling unstable features (deprecated. do not use)
+                at unstable_name_collisions detects name collision with an existing but unstable method
+                at unused_allocation detects unnecessary allocations that can be eliminated
+                at unused_assignments detect assignments that will never be read
+                at unused_attributes detects attributes that were not used by the compiler
+                at unused_braces    unnecessary braces around an expression
+                at unused_comparisons comparisons made useless by limits of the types involved
+                at unused_crate_dependencies crate dependencies that are never used
+                at unused_doc_comments detects doc comments that aren't used by rustdoc
+                at unused_extern_crates extern crates that are never used
+                at unused_features  unused features found in crate-level `#[feature]` directives
+                at unused_import_braces unnecessary braces around an imported item
+                at unused_imports   imports that are never used
+                at unused_labels    detects labels that are never used
+                at unused_lifetimes detects lifetime parameters that are never used
+                at unused_macros    detects macros that were not used
+                at unused_must_use  unused result of a type flagged as `#[must_use]`
+                at unused_mut       detect mut variables which don't need to be mutable
+                at unused_parens    `if`, `match`, `while` and `return` do not need parentheses
+                at unused_qualifications detects unnecessarily qualified names
+                at unused_results   unused result of an expression in a statement
+                at unused_unsafe    unnecessary use of an `unsafe` block
+                at unused_variables detect variables which are not used in any way
+                at variant_size_differences detects enums with widely varying variant sizes
+                at warnings         mass-change the level for lints which produce warnings
+                at where_clauses_object_safety checks the object safety of where clauses
+                at while_true       suggest using `loop { }` instead of `while true { }`
+        "#]],
+        )
+    }
+
+    #[test]
+    fn no_completion_for_incorrect_derive() {
+        check(
+            r#"
+#[derive{<|>)]
+struct Test {}
+"#,
+            expect![[r#""#]],
+        )
+    }
+
+    #[test]
+    fn derive_with_input_completion() {
+        check(
+            r#"
+#[derive(serde::Serialize, PartialEq, <|>)]
+struct Test {}
+"#,
+            expect![[r#"
+                at Clone
+                at Copy, Clone
+                at Debug
+                at Default
+                at Eq
+                at Hash
+                at Ord, PartialOrd, Eq
+                at PartialOrd
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_attribute_completion() {
+        check(
+            r#"#[<|>]"#,
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at deprecated = "…"
+                at derive(…)
+                at doc = "…"
+                at forbid(…)
+                at ignore = "…"
+                at inline(…)
+                at link
+                at link_name = "…"
+                at macro_export
+                at macro_use
+                at must_use = "…"
+                at no_mangle
+                at non_exhaustive
+                at path = "…"
+                at proc_macro
+                at proc_macro_attribute
+                at proc_macro_derive(…)
+                at repr(…)
+                at should_panic(…)
+                at target_feature = "…"
+                at test
+                at used
+                at warn(…)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_attribute_completion_inside_nested_attr() {
+        check(r#"#[cfg(<|>)]"#, expect![[]])
+    }
+
+    #[test]
+    fn test_inner_attribute_completion() {
+        check(
+            r"#![<|>]",
+            expect![[r#"
+                at allow(…)
+                at cfg(…)
+                at cfg_attr(…)
+                at deny(…)
+                at deprecated = "…"
+                at derive(…)
+                at doc = "…"
+                at feature(…)
+                at forbid(…)
+                at global_allocator
+                at ignore = "…"
+                at inline(…)
+                at link
+                at link_name = "…"
+                at macro_export
+                at macro_use
+                at must_use = "…"
+                at no_mangle
+                at no_std
+                at non_exhaustive
+                at panic_handler
+                at path = "…"
+                at proc_macro
+                at proc_macro_attribute
+                at proc_macro_derive(…)
+                at recursion_limit = …
+                at repr(…)
+                at should_panic(…)
+                at target_feature = "…"
+                at test
+                at used
+                at warn(…)
+                at windows_subsystem = "…"
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_dot.rs b/crates/ide/src/completion/complete_dot.rs
new file mode 100644
index 000000000..0b9f1798a
--- /dev/null
+++ b/crates/ide/src/completion/complete_dot.rs
@@ -0,0 +1,416 @@
+//! Completes references after dot (fields and method calls).
+
+use hir::{HasVisibility, Type};
+use rustc_hash::FxHashSet;
+use test_utils::mark;
+
+use crate::completion::{completion_context::CompletionContext, completion_item::Completions};
+
+/// Complete dot accesses, i.e. fields or methods.
+pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
+    let dot_receiver = match &ctx.dot_receiver {
+        Some(expr) => expr,
+        _ => return,
+    };
+
+    let receiver_ty = match ctx.sema.type_of_expr(&dot_receiver) {
+        Some(ty) => ty,
+        _ => return,
+    };
+
+    if ctx.is_call {
+        mark::hit!(test_no_struct_field_completion_for_method_call);
+    } else {
+        complete_fields(acc, ctx, &receiver_ty);
+    }
+    complete_methods(acc, ctx, &receiver_ty);
+}
+
+fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
+    for receiver in receiver.autoderef(ctx.db) {
+        for (field, ty) in receiver.fields(ctx.db) {
+            if ctx.scope.module().map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
+                // Skip private field. FIXME: If the definition location of the
+                // field is editable, we should show the completion
+                continue;
+            }
+            acc.add_field(ctx, field, &ty);
+        }
+        for (i, ty) in receiver.tuple_fields(ctx.db).into_iter().enumerate() {
+            // FIXME: Handle visibility
+            acc.add_tuple_field(ctx, i, &ty);
+        }
+    }
+}
+
+fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
+    if let Some(krate) = ctx.krate {
+        let mut seen_methods = FxHashSet::default();
+        let traits_in_scope = ctx.scope.traits_in_scope();
+        receiver.iterate_method_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, func| {
+            if func.self_param(ctx.db).is_some()
+                && ctx.scope.module().map_or(true, |m| func.is_visible_from(ctx.db, m))
+                && seen_methods.insert(func.name(ctx.db))
+            {
+                acc.add_function(ctx, func, None);
+            }
+            None::<()>
+        });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use test_utils::mark;
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn test_struct_field_and_method_completion() {
+        check(
+            r#"
+struct S { foo: u32 }
+impl S {
+    fn bar(&self) {}
+}
+fn foo(s: S) { s.<|> }
+"#,
+            expect![[r#"
+                me bar() fn bar(&self)
+                fd foo   u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_struct_field_completion_self() {
+        check(
+            r#"
+struct S { the_field: (u32,) }
+impl S {
+    fn foo(self) { self.<|> }
+}
+"#,
+            expect![[r#"
+                me foo()     fn foo(self)
+                fd the_field (u32,)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_struct_field_completion_autoderef() {
+        check(
+            r#"
+struct A { the_field: (u32, i32) }
+impl A {
+    fn foo(&self) { self.<|> }
+}
+"#,
+            expect![[r#"
+                me foo()     fn foo(&self)
+                fd the_field (u32, i32)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_no_struct_field_completion_for_method_call() {
+        mark::check!(test_no_struct_field_completion_for_method_call);
+        check(
+            r#"
+struct A { the_field: u32 }
+fn foo(a: A) { a.<|>() }
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn test_visibility_filtering() {
+        check(
+            r#"
+mod inner {
+    pub struct A {
+        private_field: u32,
+        pub pub_field: u32,
+        pub(crate) crate_field: u32,
+        pub(super) super_field: u32,
+    }
+}
+fn foo(a: inner::A) { a.<|> }
+"#,
+            expect![[r#"
+                fd crate_field u32
+                fd pub_field   u32
+                fd super_field u32
+            "#]],
+        );
+
+        check(
+            r#"
+struct A {}
+mod m {
+    impl super::A {
+        fn private_method(&self) {}
+        pub(super) fn the_method(&self) {}
+    }
+}
+fn foo(a: A) { a.<|> }
+"#,
+            expect![[r#"
+                me the_method() pub(super) fn the_method(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_union_field_completion() {
+        check(
+            r#"
+union U { field: u8, other: u16 }
+fn foo(u: U) { u.<|> }
+"#,
+            expect![[r#"
+                fd field u8
+                fd other u16
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_method_completion_only_fitting_impls() {
+        check(
+            r#"
+struct A<T> {}
+impl A<u32> {
+    fn the_method(&self) {}
+}
+impl A<i32> {
+    fn the_other_method(&self) {}
+}
+fn foo(a: A<u32>) { a.<|> }
+"#,
+            expect![[r#"
+                me the_method() fn the_method(&self)
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_trait_method_completion() {
+        check(
+            r#"
+struct A {}
+trait Trait { fn the_method(&self); }
+impl Trait for A {}
+fn foo(a: A) { a.<|> }
+"#,
+            expect![[r#"
+                me the_method() fn the_method(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_trait_method_completion_deduplicated() {
+        check(
+            r"
+struct A {}
+trait Trait { fn the_method(&self); }
+impl<T> Trait for T {}
+fn foo(a: &A) { a.<|> }
+",
+            expect![[r#"
+                me the_method() fn the_method(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_trait_method_from_other_module() {
+        check(
+            r"
+struct A {}
+mod m {
+    pub trait Trait { fn the_method(&self); }
+}
+use m::Trait;
+impl Trait for A {}
+fn foo(a: A) { a.<|> }
+",
+            expect![[r#"
+                me the_method() fn the_method(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_no_non_self_method() {
+        check(
+            r#"
+struct A {}
+impl A {
+    fn the_method() {}
+}
+fn foo(a: A) {
+   a.<|>
+}
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn test_tuple_field_completion() {
+        check(
+            r#"
+fn foo() {
+   let b = (0, 3.14);
+   b.<|>
+}
+"#,
+            expect![[r#"
+                fd 0 i32
+                fd 1 f64
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_tuple_field_inference() {
+        check(
+            r#"
+pub struct S;
+impl S { pub fn blah(&self) {} }
+
+struct T(S);
+
+impl T {
+    fn foo(&self) {
+        // FIXME: This doesn't work without the trailing `a` as `0.` is a float
+        self.0.a<|>
+    }
+}
+"#,
+            expect![[r#"
+                me blah() pub fn blah(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_completion_works_in_consts() {
+        check(
+            r#"
+struct A { the_field: u32 }
+const X: u32 = {
+    A { the_field: 92 }.<|>
+};
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_1() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+struct A { the_field: u32 }
+fn foo(a: A) {
+    m!(a.x<|>)
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_2() {
+        // this doesn't work yet because the macro doesn't expand without the token -- maybe it can be fixed with better recovery
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+struct A { the_field: u32 }
+fn foo(a: A) {
+    m!(a.<|>)
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_recursive_1() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+struct A { the_field: u32 }
+fn foo(a: A) {
+    m!(m!(m!(a.x<|>)))
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn macro_expansion_resilient() {
+        check(
+            r#"
+macro_rules! dbg {
+    () => {};
+    ($val:expr) => {
+        match $val { tmp => { tmp } }
+    };
+    // Trailing comma with single argument is ignored
+    ($val:expr,) => { $crate::dbg!($val) };
+    ($($val:expr),+ $(,)?) => {
+        ($($crate::dbg!($val)),+,)
+    };
+}
+struct A { the_field: u32 }
+fn foo(a: A) {
+    dbg!(a.<|>)
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_method_completion_issue_3547() {
+        check(
+            r#"
+struct HashSet<T> {}
+impl<T> HashSet<T> {
+    pub fn the_method(&self) {}
+}
+fn foo() {
+    let s: HashSet<_>;
+    s.<|>
+}
+"#,
+            expect![[r#"
+                me the_method() pub fn the_method(&self)
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_fn_param.rs b/crates/ide/src/completion/complete_fn_param.rs
new file mode 100644
index 000000000..9efe25461
--- /dev/null
+++ b/crates/ide/src/completion/complete_fn_param.rs
@@ -0,0 +1,135 @@
+//! See `complete_fn_param`.
+
+use rustc_hash::FxHashMap;
+use syntax::{
+    ast::{self, ModuleItemOwner},
+    match_ast, AstNode,
+};
+
+use crate::completion::{CompletionContext, CompletionItem, CompletionKind, Completions};
+
+/// Complete repeated parameters, both name and type. For example, if all
+/// functions in a file have a `spam: &mut Spam` parameter, a completion with
+/// `spam: &mut Spam` insert text/label and `spam` lookup string will be
+/// suggested.
+pub(super) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.is_param {
+        return;
+    }
+
+    let mut params = FxHashMap::default();
+
+    let me = ctx.token.ancestors().find_map(ast::Fn::cast);
+    let mut process_fn = |func: ast::Fn| {
+        if Some(&func) == me.as_ref() {
+            return;
+        }
+        func.param_list().into_iter().flat_map(|it| it.params()).for_each(|param| {
+            let text = param.syntax().text().to_string();
+            params.entry(text).or_insert(param);
+        })
+    };
+
+    for node in ctx.token.parent().ancestors() {
+        match_ast! {
+            match node {
+                ast::SourceFile(it) => it.items().filter_map(|item| match item {
+                    ast::Item::Fn(it) => Some(it),
+                    _ => None,
+                }).for_each(&mut process_fn),
+                ast::ItemList(it) => it.items().filter_map(|item| match item {
+                    ast::Item::Fn(it) => Some(it),
+                    _ => None,
+                }).for_each(&mut process_fn),
+                ast::AssocItemList(it) => it.assoc_items().filter_map(|item| match item {
+                    ast::AssocItem::Fn(it) => Some(it),
+                    _ => None,
+                }).for_each(&mut process_fn),
+                _ => continue,
+            }
+        };
+    }
+
+    params
+        .into_iter()
+        .filter_map(|(label, param)| {
+            let lookup = param.pat()?.syntax().text().to_string();
+            Some((label, lookup))
+        })
+        .for_each(|(label, lookup)| {
+            CompletionItem::new(CompletionKind::Magic, ctx.source_range(), label)
+                .kind(crate::CompletionItemKind::Binding)
+                .lookup_by(lookup)
+                .add_to(acc)
+        });
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Magic);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn test_param_completion_last_param() {
+        check(
+            r#"
+fn foo(file_id: FileId) {}
+fn bar(file_id: FileId) {}
+fn baz(file<|>) {}
+"#,
+            expect![[r#"
+                bn file_id: FileId
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_param_completion_nth_param() {
+        check(
+            r#"
+fn foo(file_id: FileId) {}
+fn baz(file<|>, x: i32) {}
+"#,
+            expect![[r#"
+                bn file_id: FileId
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_param_completion_trait_param() {
+        check(
+            r#"
+pub(crate) trait SourceRoot {
+    pub fn contains(&self, file_id: FileId) -> bool;
+    pub fn module_map(&self) -> &ModuleMap;
+    pub fn lines(&self, file_id: FileId) -> &LineIndex;
+    pub fn syntax(&self, file<|>)
+}
+"#,
+            expect![[r#"
+                bn file_id: FileId
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_param_in_inner_function() {
+        check(
+            r#"
+fn outer(text: String) {
+    fn inner(<|>)
+}
+"#,
+            expect![[r#"
+                bn text: String
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion/complete_keyword.rs b/crates/ide/src/completion/complete_keyword.rs
new file mode 100644
index 000000000..95e4ff1ac
--- /dev/null
+++ b/crates/ide/src/completion/complete_keyword.rs
@@ -0,0 +1,527 @@
+//! FIXME: write short doc here
+
+use syntax::{ast, SyntaxKind};
+use test_utils::mark;
+
+use crate::completion::{
+    CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions,
+};
+
+pub(super) fn complete_use_tree_keyword(acc: &mut Completions, ctx: &CompletionContext) {
+    // complete keyword "crate" in use stmt
+    let source_range = ctx.source_range();
+
+    if ctx.use_item_syntax.is_some() {
+        if ctx.path_qual.is_none() {
+            CompletionItem::new(CompletionKind::Keyword, source_range, "crate::")
+                .kind(CompletionItemKind::Keyword)
+                .insert_text("crate::")
+                .add_to(acc);
+        }
+        CompletionItem::new(CompletionKind::Keyword, source_range, "self")
+            .kind(CompletionItemKind::Keyword)
+            .add_to(acc);
+        CompletionItem::new(CompletionKind::Keyword, source_range, "super::")
+            .kind(CompletionItemKind::Keyword)
+            .insert_text("super::")
+            .add_to(acc);
+    }
+
+    // Suggest .await syntax for types that implement Future trait
+    if let Some(receiver) = &ctx.dot_receiver {
+        if let Some(ty) = ctx.sema.type_of_expr(receiver) {
+            if ty.impls_future(ctx.db) {
+                CompletionItem::new(CompletionKind::Keyword, ctx.source_range(), "await")
+                    .kind(CompletionItemKind::Keyword)
+                    .detail("expr.await")
+                    .insert_text("await")
+                    .add_to(acc);
+            }
+        };
+    }
+}
+
+pub(super) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionContext) {
+    if ctx.token.kind() == SyntaxKind::COMMENT {
+        mark::hit!(no_keyword_completion_in_comments);
+        return;
+    }
+
+    let has_trait_or_impl_parent = ctx.has_impl_parent || ctx.has_trait_parent;
+    if ctx.trait_as_prev_sibling || ctx.impl_as_prev_sibling {
+        add_keyword(ctx, acc, "where", "where ");
+        return;
+    }
+    if ctx.unsafe_is_prev {
+        if ctx.has_item_list_or_source_file_parent || ctx.block_expr_parent {
+            add_keyword(ctx, acc, "fn", "fn $0() {}")
+        }
+
+        if (ctx.has_item_list_or_source_file_parent) || ctx.block_expr_parent {
+            add_keyword(ctx, acc, "trait", "trait $0 {}");
+            add_keyword(ctx, acc, "impl", "impl $0 {}");
+        }
+
+        return;
+    }
+    if ctx.has_item_list_or_source_file_parent || has_trait_or_impl_parent || ctx.block_expr_parent
+    {
+        add_keyword(ctx, acc, "fn", "fn $0() {}");
+    }
+    if (ctx.has_item_list_or_source_file_parent) || ctx.block_expr_parent {
+        add_keyword(ctx, acc, "use", "use ");
+        add_keyword(ctx, acc, "impl", "impl $0 {}");
+        add_keyword(ctx, acc, "trait", "trait $0 {}");
+    }
+
+    if ctx.has_item_list_or_source_file_parent {
+        add_keyword(ctx, acc, "enum", "enum $0 {}");
+        add_keyword(ctx, acc, "struct", "struct $0");
+        add_keyword(ctx, acc, "union", "union $0 {}");
+    }
+
+    if ctx.is_expr {
+        add_keyword(ctx, acc, "match", "match $0 {}");
+        add_keyword(ctx, acc, "while", "while $0 {}");
+        add_keyword(ctx, acc, "loop", "loop {$0}");
+        add_keyword(ctx, acc, "if", "if ");
+        add_keyword(ctx, acc, "if let", "if let ");
+    }
+
+    if ctx.if_is_prev || ctx.block_expr_parent {
+        add_keyword(ctx, acc, "let", "let ");
+    }
+
+    if ctx.after_if {
+        add_keyword(ctx, acc, "else", "else {$0}");
+        add_keyword(ctx, acc, "else if", "else if $0 {}");
+    }
+    if (ctx.has_item_list_or_source_file_parent) || ctx.block_expr_parent {
+        add_keyword(ctx, acc, "mod", "mod $0 {}");
+    }
+    if ctx.bind_pat_parent || ctx.ref_pat_parent {
+        add_keyword(ctx, acc, "mut", "mut ");
+    }
+    if ctx.has_item_list_or_source_file_parent || has_trait_or_impl_parent || ctx.block_expr_parent
+    {
+        add_keyword(ctx, acc, "const", "const ");
+        add_keyword(ctx, acc, "type", "type ");
+    }
+    if (ctx.has_item_list_or_source_file_parent) || ctx.block_expr_parent {
+        add_keyword(ctx, acc, "static", "static ");
+    };
+    if (ctx.has_item_list_or_source_file_parent) || ctx.block_expr_parent {
+        add_keyword(ctx, acc, "extern", "extern ");
+    }
+    if ctx.has_item_list_or_source_file_parent
+        || has_trait_or_impl_parent
+        || ctx.block_expr_parent
+        || ctx.is_match_arm
+    {
+        add_keyword(ctx, acc, "unsafe", "unsafe ");
+    }
+    if ctx.in_loop_body {
+        if ctx.can_be_stmt {
+            add_keyword(ctx, acc, "continue", "continue;");
+            add_keyword(ctx, acc, "break", "break;");
+        } else {
+            add_keyword(ctx, acc, "continue", "continue");
+            add_keyword(ctx, acc, "break", "break");
+        }
+    }
+    if ctx.has_item_list_or_source_file_parent || ctx.has_impl_parent {
+        add_keyword(ctx, acc, "pub", "pub ")
+    }
+
+    if !ctx.is_trivial_path {
+        return;
+    }
+    let fn_def = match &ctx.function_syntax {
+        Some(it) => it,
+        None => return,
+    };
+    acc.add_all(complete_return(ctx, &fn_def, ctx.can_be_stmt));
+}
+
+fn keyword(ctx: &CompletionContext, kw: &str, snippet: &str) -> CompletionItem {
+    let res = CompletionItem::new(CompletionKind::Keyword, ctx.source_range(), kw)
+        .kind(CompletionItemKind::Keyword);
+
+    match ctx.config.snippet_cap {
+        Some(cap) => res.insert_snippet(cap, snippet),
+        _ => res.insert_text(if snippet.contains('$') { kw } else { snippet }),
+    }
+    .build()
+}
+
+fn add_keyword(ctx: &CompletionContext, acc: &mut Completions, kw: &str, snippet: &str) {
+    acc.add(keyword(ctx, kw, snippet));
+}
+
+fn complete_return(
+    ctx: &CompletionContext,
+    fn_def: &ast::Fn,
+    can_be_stmt: bool,
+) -> Option<CompletionItem> {
+    let snip = match (can_be_stmt, fn_def.ret_type().is_some()) {
+        (true, true) => "return $0;",
+        (true, false) => "return;",
+        (false, true) => "return $0",
+        (false, false) => "return",
+    };
+    Some(keyword(ctx, "return", snip))
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{
+        test_utils::{check_edit, completion_list},
+        CompletionKind,
+    };
+    use test_utils::mark;
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Keyword);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn test_keywords_in_use_stmt() {
+        check(
+            r"use <|>",
+            expect![[r#"
+                kw crate::
+                kw self
+                kw super::
+            "#]],
+        );
+
+        check(
+            r"use a::<|>",
+            expect![[r#"
+                kw self
+                kw super::
+            "#]],
+        );
+
+        check(
+            r"use a::{b, <|>}",
+            expect![[r#"
+                kw self
+                kw super::
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_at_source_file_level() {
+        check(
+            r"m<|>",
+            expect![[r#"
+                kw const
+                kw enum
+                kw extern
+                kw fn
+                kw impl
+                kw mod
+                kw pub
+                kw static
+                kw struct
+                kw trait
+                kw type
+                kw union
+                kw unsafe
+                kw use
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_in_function() {
+        check(
+            r"fn quux() { <|> }",
+            expect![[r#"
+                kw const
+                kw extern
+                kw fn
+                kw if
+                kw if let
+                kw impl
+                kw let
+                kw loop
+                kw match
+                kw mod
+                kw return
+                kw static
+                kw trait
+                kw type
+                kw unsafe
+                kw use
+                kw while
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_inside_block() {
+        check(
+            r"fn quux() { if true { <|> } }",
+            expect![[r#"
+                kw const
+                kw extern
+                kw fn
+                kw if
+                kw if let
+                kw impl
+                kw let
+                kw loop
+                kw match
+                kw mod
+                kw return
+                kw static
+                kw trait
+                kw type
+                kw unsafe
+                kw use
+                kw while
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_after_if() {
+        check(
+            r#"fn quux() { if true { () } <|> }"#,
+            expect![[r#"
+                kw const
+                kw else
+                kw else if
+                kw extern
+                kw fn
+                kw if
+                kw if let
+                kw impl
+                kw let
+                kw loop
+                kw match
+                kw mod
+                kw return
+                kw static
+                kw trait
+                kw type
+                kw unsafe
+                kw use
+                kw while
+            "#]],
+        );
+        check_edit(
+            "else",
+            r#"fn quux() { if true { () } <|> }"#,
+            r#"fn quux() { if true { () } else {$0} }"#,
+        );
+    }
+
+    #[test]
+    fn test_keywords_in_match_arm() {
+        check(
+            r#"
+fn quux() -> i32 {
+    match () { () => <|> }
+}
+"#,
+            expect![[r#"
+                kw if
+                kw if let
+                kw loop
+                kw match
+                kw return
+                kw unsafe
+                kw while
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_in_trait_def() {
+        check(
+            r"trait My { <|> }",
+            expect![[r#"
+                kw const
+                kw fn
+                kw type
+                kw unsafe
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_in_impl_def() {
+        check(
+            r"impl My { <|> }",
+            expect![[r#"
+                kw const
+                kw fn
+                kw pub
+                kw type
+                kw unsafe
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_in_loop() {
+        check(
+            r"fn my() { loop { <|> } }",
+            expect![[r#"
+                kw break
+                kw const
+                kw continue
+                kw extern
+                kw fn
+                kw if
+                kw if let
+                kw impl
+                kw let
+                kw loop
+                kw match
+                kw mod
+                kw return
+                kw static
+                kw trait
+                kw type
+                kw unsafe
+                kw use
+                kw while
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_after_unsafe_in_item_list() {
+        check(
+            r"unsafe <|>",
+            expect![[r#"
+                kw fn
+                kw impl
+                kw trait
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_keywords_after_unsafe_in_block_expr() {
+        check(
+            r"fn my_fn() { unsafe <|> }",
+            expect![[r#"
+                kw fn
+                kw impl
+                kw trait
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_mut_in_ref_and_in_fn_parameters_list() {
+        check(
+            r"fn my_fn(&<|>) {}",
+            expect![[r#"
+                kw mut
+            "#]],
+        );
+        check(
+            r"fn my_fn(<|>) {}",
+            expect![[r#"
+                kw mut
+            "#]],
+        );
+        check(
+            r"fn my_fn() { let &<|> }",
+            expect![[r#"
+                kw mut
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_where_keyword() {
+        check(
+            r"trait A <|>",
+            expect![[r#"
+                kw where
+            "#]],
+        );
+        check(
+            r"impl A <|>",
+            expect![[r#"
+                kw where
+            "#]],
+        );
+    }
+
+    #[test]
+    fn no_keyword_completion_in_comments() {
+        mark::check!(no_keyword_completion_in_comments);
+        check(
+            r#"
+fn test() {
+    let x = 2; // A comment<|>
+}
+"#,
+            expect![[""]],
+        );
+        check(
+            r#"
+/*
+Some multi-line comment<|>
+*/
+"#,
+            expect![[""]],
+        );
+        check(
+            r#"
+/// Some doc comment
+/// let test<|> = 1
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn test_completion_await_impls_future() {
+        check(
+            r#"
+//- /main.rs
+use std::future::*;
+struct A {}
+impl Future for A {}
+fn foo(a: A) { a.<|> }
+
+//- /std/lib.rs
+pub mod future {
+    #[lang = "future_trait"]
+    pub trait Future {}
+}
+"#,
+            expect![[r#"
+                kw await expr.await
+            "#]],
+        )
+    }
+
+    #[test]
+    fn after_let() {
+        check(
+            r#"fn main() { let _ = <|> }"#,
+            expect![[r#"
+                kw if
+                kw if let
+                kw loop
+                kw match
+                kw return
+                kw while
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion/complete_macro_in_item_position.rs b/crates/ide/src/completion/complete_macro_in_item_position.rs
new file mode 100644
index 000000000..fc8625d8e
--- /dev/null
+++ b/crates/ide/src/completion/complete_macro_in_item_position.rs
@@ -0,0 +1,41 @@
+//! FIXME: write short doc here
+
+use crate::completion::{CompletionContext, Completions};
+
+pub(super) fn complete_macro_in_item_position(acc: &mut Completions, ctx: &CompletionContext) {
+    // Show only macros in top level.
+    if ctx.is_new_item {
+        ctx.scope.process_all_names(&mut |name, res| {
+            if let hir::ScopeDef::MacroDef(mac) = res {
+                acc.add_macro(ctx, Some(name.to_string()), mac);
+            }
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn completes_macros_as_item() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+fn foo() {}
+
+<|>
+"#,
+            expect![[r#"
+                ma foo!(…) macro_rules! foo
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion/complete_pattern.rs b/crates/ide/src/completion/complete_pattern.rs
new file mode 100644
index 000000000..5a13574d4
--- /dev/null
+++ b/crates/ide/src/completion/complete_pattern.rs
@@ -0,0 +1,88 @@
+//! FIXME: write short doc here
+
+use crate::completion::{CompletionContext, Completions};
+
+/// Completes constats and paths in patterns.
+pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.is_pat_binding_or_const {
+        return;
+    }
+    if ctx.record_pat_syntax.is_some() {
+        return;
+    }
+
+    // FIXME: ideally, we should look at the type we are matching against and
+    // suggest variants + auto-imports
+    ctx.scope.process_all_names(&mut |name, res| {
+        match &res {
+            hir::ScopeDef::ModuleDef(def) => match def {
+                hir::ModuleDef::Adt(hir::Adt::Enum(..))
+                | hir::ModuleDef::Adt(hir::Adt::Struct(..))
+                | hir::ModuleDef::EnumVariant(..)
+                | hir::ModuleDef::Const(..)
+                | hir::ModuleDef::Module(..) => (),
+                _ => return,
+            },
+            hir::ScopeDef::MacroDef(_) => (),
+            _ => return,
+        };
+
+        acc.add_resolution(ctx, name.to_string(), &res)
+    });
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn completes_enum_variants_and_modules() {
+        check(
+            r#"
+enum E { X }
+use self::E::X;
+const Z: E = E::X;
+mod m {}
+
+static FOO: E = E::X;
+struct Bar { f: u32 }
+
+fn foo() {
+   match E::X { <|> }
+}
+"#,
+            expect![[r#"
+                st Bar
+                en E
+                ev X   ()
+                ct Z
+                md m
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+enum E { X }
+
+fn foo() {
+   m!(match E::X { <|> })
+}
+"#,
+            expect![[r#"
+                en E
+                ma m!(…) macro_rules! m
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_postfix.rs b/crates/ide/src/completion/complete_postfix.rs
new file mode 100644
index 000000000..84c4e129d
--- /dev/null
+++ b/crates/ide/src/completion/complete_postfix.rs
@@ -0,0 +1,378 @@
+//! FIXME: write short doc here
+use assists::utils::TryEnum;
+use syntax::{
+    ast::{self, AstNode},
+    TextRange, TextSize,
+};
+use text_edit::TextEdit;
+
+use crate::{
+    completion::{
+        completion_config::SnippetCap,
+        completion_context::CompletionContext,
+        completion_item::{Builder, CompletionKind, Completions},
+    },
+    CompletionItem, CompletionItemKind,
+};
+
+pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.config.enable_postfix_completions {
+        return;
+    }
+
+    let dot_receiver = match &ctx.dot_receiver {
+        Some(it) => it,
+        None => return,
+    };
+
+    let receiver_text =
+        get_receiver_text(dot_receiver, ctx.dot_receiver_is_ambiguous_float_literal);
+
+    let receiver_ty = match ctx.sema.type_of_expr(&dot_receiver) {
+        Some(it) => it,
+        None => return,
+    };
+
+    let cap = match ctx.config.snippet_cap {
+        Some(it) => it,
+        None => return,
+    };
+    let try_enum = TryEnum::from_ty(&ctx.sema, &receiver_ty);
+    if let Some(try_enum) = &try_enum {
+        match try_enum {
+            TryEnum::Result => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "ifl",
+                    "if let Ok {}",
+                    &format!("if let Ok($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "while",
+                    "while let Ok {}",
+                    &format!("while let Ok($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+            }
+            TryEnum::Option => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "ifl",
+                    "if let Some {}",
+                    &format!("if let Some($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "while",
+                    "while let Some {}",
+                    &format!("while let Some($1) = {} {{\n    $0\n}}", receiver_text),
+                )
+                .add_to(acc);
+            }
+        }
+    } else if receiver_ty.is_bool() || receiver_ty.is_unknown() {
+        postfix_snippet(
+            ctx,
+            cap,
+            &dot_receiver,
+            "if",
+            "if expr {}",
+            &format!("if {} {{\n    $0\n}}", receiver_text),
+        )
+        .add_to(acc);
+        postfix_snippet(
+            ctx,
+            cap,
+            &dot_receiver,
+            "while",
+            "while expr {}",
+            &format!("while {} {{\n    $0\n}}", receiver_text),
+        )
+        .add_to(acc);
+        postfix_snippet(ctx, cap, &dot_receiver, "not", "!expr", &format!("!{}", receiver_text))
+            .add_to(acc);
+    }
+
+    postfix_snippet(ctx, cap, &dot_receiver, "ref", "&expr", &format!("&{}", receiver_text))
+        .add_to(acc);
+    postfix_snippet(
+        ctx,
+        cap,
+        &dot_receiver,
+        "refm",
+        "&mut expr",
+        &format!("&mut {}", receiver_text),
+    )
+    .add_to(acc);
+
+    // The rest of the postfix completions create an expression that moves an argument,
+    // so it's better to consider references now to avoid breaking the compilation
+    let dot_receiver = include_references(dot_receiver);
+    let receiver_text =
+        get_receiver_text(&dot_receiver, ctx.dot_receiver_is_ambiguous_float_literal);
+
+    match try_enum {
+        Some(try_enum) => match try_enum {
+            TryEnum::Result => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "match",
+                    "match expr {}",
+                    &format!("match {} {{\n    Ok(${{1:_}}) => {{$2}},\n    Err(${{3:_}}) => {{$0}},\n}}", receiver_text),
+                )
+                .add_to(acc);
+            }
+            TryEnum::Option => {
+                postfix_snippet(
+                    ctx,
+                    cap,
+                    &dot_receiver,
+                    "match",
+                    "match expr {}",
+                    &format!(
+                        "match {} {{\n    Some(${{1:_}}) => {{$2}},\n    None => {{$0}},\n}}",
+                        receiver_text
+                    ),
+                )
+                .add_to(acc);
+            }
+        },
+        None => {
+            postfix_snippet(
+                ctx,
+                cap,
+                &dot_receiver,
+                "match",
+                "match expr {}",
+                &format!("match {} {{\n    ${{1:_}} => {{$0}},\n}}", receiver_text),
+            )
+            .add_to(acc);
+        }
+    }
+
+    postfix_snippet(
+        ctx,
+        cap,
+        &dot_receiver,
+        "box",
+        "Box::new(expr)",
+        &format!("Box::new({})", receiver_text),
+    )
+    .add_to(acc);
+
+    postfix_snippet(
+        ctx,
+        cap,
+        &dot_receiver,
+        "dbg",
+        "dbg!(expr)",
+        &format!("dbg!({})", receiver_text),
+    )
+    .add_to(acc);
+
+    postfix_snippet(
+        ctx,
+        cap,
+        &dot_receiver,
+        "call",
+        "function(expr)",
+        &format!("${{1}}({})", receiver_text),
+    )
+    .add_to(acc);
+}
+
+fn get_receiver_text(receiver: &ast::Expr, receiver_is_ambiguous_float_literal: bool) -> String {
+    if receiver_is_ambiguous_float_literal {
+        let text = receiver.syntax().text();
+        let without_dot = ..text.len() - TextSize::of('.');
+        text.slice(without_dot).to_string()
+    } else {
+        receiver.to_string()
+    }
+}
+
+fn include_references(initial_element: &ast::Expr) -> ast::Expr {
+    let mut resulting_element = initial_element.clone();
+    while let Some(parent_ref_element) =
+        resulting_element.syntax().parent().and_then(ast::RefExpr::cast)
+    {
+        resulting_element = ast::Expr::from(parent_ref_element);
+    }
+    resulting_element
+}
+
+fn postfix_snippet(
+    ctx: &CompletionContext,
+    cap: SnippetCap,
+    receiver: &ast::Expr,
+    label: &str,
+    detail: &str,
+    snippet: &str,
+) -> Builder {
+    let edit = {
+        let receiver_syntax = receiver.syntax();
+        let receiver_range = ctx.sema.original_range(receiver_syntax).range;
+        let delete_range = TextRange::new(receiver_range.start(), ctx.source_range().end());
+        TextEdit::replace(delete_range, snippet.to_string())
+    };
+    CompletionItem::new(CompletionKind::Postfix, ctx.source_range(), label)
+        .detail(detail)
+        .kind(CompletionItemKind::Snippet)
+        .snippet_edit(cap, edit)
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{
+        test_utils::{check_edit, completion_list},
+        CompletionKind,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Postfix);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn postfix_completion_works_for_trivial_path_expression() {
+        check(
+            r#"
+fn main() {
+    let bar = true;
+    bar.<|>
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn if    if expr {}
+                sn match match expr {}
+                sn not   !expr
+                sn ref   &expr
+                sn refm  &mut expr
+                sn while while expr {}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn postfix_type_filtering() {
+        check(
+            r#"
+fn main() {
+    let bar: u8 = 12;
+    bar.<|>
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn match match expr {}
+                sn ref   &expr
+                sn refm  &mut expr
+            "#]],
+        )
+    }
+
+    #[test]
+    fn option_iflet() {
+        check_edit(
+            "ifl",
+            r#"
+enum Option<T> { Some(T), None }
+
+fn main() {
+    let bar = Option::Some(true);
+    bar.<|>
+}
+"#,
+            r#"
+enum Option<T> { Some(T), None }
+
+fn main() {
+    let bar = Option::Some(true);
+    if let Some($1) = bar {
+    $0
+}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn result_match() {
+        check_edit(
+            "match",
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+
+fn main() {
+    let bar = Result::Ok(true);
+    bar.<|>
+}
+"#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+
+fn main() {
+    let bar = Result::Ok(true);
+    match bar {
+    Ok(${1:_}) => {$2},
+    Err(${3:_}) => {$0},
+}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn postfix_completion_works_for_ambiguous_float_literal() {
+        check_edit("refm", r#"fn main() { 42.<|> }"#, r#"fn main() { &mut 42 }"#)
+    }
+
+    #[test]
+    fn works_in_simple_macro() {
+        check_edit(
+            "dbg",
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+fn main() {
+    let bar: u8 = 12;
+    m!(bar.d<|>)
+}
+"#,
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+fn main() {
+    let bar: u8 = 12;
+    m!(dbg!(bar))
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn postfix_completion_for_references() {
+        check_edit("dbg", r#"fn main() { &&42.<|> }"#, r#"fn main() { dbg!(&&42) }"#);
+        check_edit("refm", r#"fn main() { &&42.<|> }"#, r#"fn main() { &&&mut 42 }"#);
+    }
+}
diff --git a/crates/ide/src/completion/complete_qualified_path.rs b/crates/ide/src/completion/complete_qualified_path.rs
new file mode 100644
index 000000000..accb09f7e
--- /dev/null
+++ b/crates/ide/src/completion/complete_qualified_path.rs
@@ -0,0 +1,733 @@
+//! Completion of paths, i.e. `some::prefix::<|>`.
+
+use hir::{Adt, HasVisibility, PathResolution, ScopeDef};
+use rustc_hash::FxHashSet;
+use syntax::AstNode;
+use test_utils::mark;
+
+use crate::completion::{CompletionContext, Completions};
+
+pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionContext) {
+    let path = match &ctx.path_qual {
+        Some(path) => path.clone(),
+        None => return,
+    };
+
+    if ctx.attribute_under_caret.is_some() {
+        return;
+    }
+
+    let context_module = ctx.scope.module();
+
+    let resolution = match ctx.sema.resolve_path(&path) {
+        Some(res) => res,
+        None => return,
+    };
+
+    // Add associated types on type parameters and `Self`.
+    resolution.assoc_type_shorthand_candidates(ctx.db, |alias| {
+        acc.add_type_alias(ctx, alias);
+        None::<()>
+    });
+
+    match resolution {
+        PathResolution::Def(hir::ModuleDef::Module(module)) => {
+            let module_scope = module.scope(ctx.db, context_module);
+            for (name, def) in module_scope {
+                if ctx.use_item_syntax.is_some() {
+                    if let ScopeDef::Unknown = def {
+                        if let Some(name_ref) = ctx.name_ref_syntax.as_ref() {
+                            if name_ref.syntax().text() == name.to_string().as_str() {
+                                // for `use self::foo<|>`, don't suggest `foo` as a completion
+                                mark::hit!(dont_complete_current_use);
+                                continue;
+                            }
+                        }
+                    }
+                }
+
+                acc.add_resolution(ctx, name.to_string(), &def);
+            }
+        }
+        PathResolution::Def(def @ hir::ModuleDef::Adt(_))
+        | PathResolution::Def(def @ hir::ModuleDef::TypeAlias(_)) => {
+            if let hir::ModuleDef::Adt(Adt::Enum(e)) = def {
+                for variant in e.variants(ctx.db) {
+                    acc.add_enum_variant(ctx, variant, None);
+                }
+            }
+            let ty = match def {
+                hir::ModuleDef::Adt(adt) => adt.ty(ctx.db),
+                hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
+                _ => unreachable!(),
+            };
+
+            // XXX: For parity with Rust bug #22519, this does not complete Ty::AssocType.
+            // (where AssocType is defined on a trait, not an inherent impl)
+
+            let krate = ctx.krate;
+            if let Some(krate) = krate {
+                let traits_in_scope = ctx.scope.traits_in_scope();
+                ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
+                    if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                        return None;
+                    }
+                    match item {
+                        hir::AssocItem::Function(func) => {
+                            acc.add_function(ctx, func, None);
+                        }
+                        hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                        hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                    }
+                    None::<()>
+                });
+
+                // Iterate assoc types separately
+                ty.iterate_assoc_items(ctx.db, krate, |item| {
+                    if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                        return None;
+                    }
+                    match item {
+                        hir::AssocItem::Function(_) | hir::AssocItem::Const(_) => {}
+                        hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                    }
+                    None::<()>
+                });
+            }
+        }
+        PathResolution::Def(hir::ModuleDef::Trait(t)) => {
+            // Handles `Trait::assoc` as well as `<Ty as Trait>::assoc`.
+            for item in t.items(ctx.db) {
+                if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                    continue;
+                }
+                match item {
+                    hir::AssocItem::Function(func) => {
+                        acc.add_function(ctx, func, None);
+                    }
+                    hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                    hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                }
+            }
+        }
+        PathResolution::TypeParam(_) | PathResolution::SelfType(_) => {
+            if let Some(krate) = ctx.krate {
+                let ty = match resolution {
+                    PathResolution::TypeParam(param) => param.ty(ctx.db),
+                    PathResolution::SelfType(impl_def) => impl_def.target_ty(ctx.db),
+                    _ => return,
+                };
+
+                let traits_in_scope = ctx.scope.traits_in_scope();
+                let mut seen = FxHashSet::default();
+                ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
+                    if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                        return None;
+                    }
+
+                    // We might iterate candidates of a trait multiple times here, so deduplicate
+                    // them.
+                    if seen.insert(item) {
+                        match item {
+                            hir::AssocItem::Function(func) => {
+                                acc.add_function(ctx, func, None);
+                            }
+                            hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                            hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                        }
+                    }
+                    None::<()>
+                });
+            }
+        }
+        _ => {}
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use test_utils::mark;
+
+    use crate::completion::{
+        test_utils::{check_edit, completion_list},
+        CompletionKind,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual);
+    }
+
+    fn check_builtin(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::BuiltinType);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn dont_complete_current_use() {
+        mark::check!(dont_complete_current_use);
+        check(r#"use self::foo<|>;"#, expect![[""]]);
+    }
+
+    #[test]
+    fn dont_complete_current_use_in_braces_with_glob() {
+        check(
+            r#"
+mod foo { pub struct S; }
+use self::{foo::*, bar<|>};
+"#,
+            expect![[r#"
+                st S
+                md foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn dont_complete_primitive_in_use() {
+        check_builtin(r#"use self::<|>;"#, expect![[""]]);
+    }
+
+    #[test]
+    fn dont_complete_primitive_in_module_scope() {
+        check_builtin(r#"fn foo() { self::<|> }"#, expect![[""]]);
+    }
+
+    #[test]
+    fn completes_primitives() {
+        check_builtin(
+            r#"fn main() { let _: <|> = 92; }"#,
+            expect![[r#"
+                bt bool
+                bt char
+                bt f32
+                bt f64
+                bt i128
+                bt i16
+                bt i32
+                bt i64
+                bt i8
+                bt isize
+                bt str
+                bt u128
+                bt u16
+                bt u32
+                bt u64
+                bt u8
+                bt usize
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_mod_with_same_name_as_function() {
+        check(
+            r#"
+use self::my::<|>;
+
+mod my { pub struct Bar; }
+fn my() {}
+"#,
+            expect![[r#"
+                st Bar
+            "#]],
+        );
+    }
+
+    #[test]
+    fn filters_visibility() {
+        check(
+            r#"
+use self::my::<|>;
+
+mod my {
+    struct Bar;
+    pub struct Foo;
+    pub use Bar as PublicBar;
+}
+"#,
+            expect![[r#"
+                st Foo
+                st PublicBar
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_use_item_starting_with_self() {
+        check(
+            r#"
+use self::m::<|>;
+
+mod m { pub struct Bar; }
+"#,
+            expect![[r#"
+                st Bar
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_use_item_starting_with_crate() {
+        check(
+            r#"
+//- /lib.rs
+mod foo;
+struct Spam;
+//- /foo.rs
+use crate::Sp<|>
+"#,
+            expect![[r#"
+                st Spam
+                md foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_nested_use_tree() {
+        check(
+            r#"
+//- /lib.rs
+mod foo;
+struct Spam;
+//- /foo.rs
+use crate::{Sp<|>};
+"#,
+            expect![[r#"
+                st Spam
+                md foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_deeply_nested_use_tree() {
+        check(
+            r#"
+//- /lib.rs
+mod foo;
+pub mod bar {
+    pub mod baz {
+        pub struct Spam;
+    }
+}
+//- /foo.rs
+use crate::{bar::{baz::Sp<|>}};
+"#,
+            expect![[r#"
+                st Spam
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_enum_variant() {
+        check(
+            r#"
+enum E { Foo, Bar(i32) }
+fn foo() { let _ = E::<|> }
+"#,
+            expect![[r#"
+                ev Bar(…) (i32)
+                ev Foo    ()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_struct_associated_items() {
+        check(
+            r#"
+//- /lib.rs
+struct S;
+
+impl S {
+    fn a() {}
+    fn b(&self) {}
+    const C: i32 = 42;
+    type T = i32;
+}
+
+fn foo() { let _ = S::<|> }
+"#,
+            expect![[r#"
+                ct C   const C: i32 = 42;
+                ta T   type T = i32;
+                fn a() fn a()
+                me b() fn b(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn associated_item_visibility() {
+        check(
+            r#"
+struct S;
+
+mod m {
+    impl super::S {
+        pub(super) fn public_method() { }
+        fn private_method() { }
+        pub(super) type PublicType = u32;
+        type PrivateType = u32;
+        pub(super) const PUBLIC_CONST: u32 = 1;
+        const PRIVATE_CONST: u32 = 1;
+    }
+}
+
+fn foo() { let _ = S::<|> }
+"#,
+            expect![[r#"
+                ct PUBLIC_CONST    pub(super) const PUBLIC_CONST: u32 = 1;
+                ta PublicType      pub(super) type PublicType = u32;
+                fn public_method() pub(super) fn public_method()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_enum_associated_method() {
+        check(
+            r#"
+enum E {};
+impl E { fn m() { } }
+
+fn foo() { let _ = E::<|> }
+        "#,
+            expect![[r#"
+                fn m() fn m()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_union_associated_method() {
+        check(
+            r#"
+union U {};
+impl U { fn m() { } }
+
+fn foo() { let _ = U::<|> }
+"#,
+            expect![[r#"
+                fn m() fn m()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_use_paths_across_crates() {
+        check(
+            r#"
+//- /main.rs
+use foo::<|>;
+
+//- /foo/lib.rs
+pub mod bar { pub struct S; }
+"#,
+            expect![[r#"
+                md bar
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_trait_associated_method_1() {
+        check(
+            r#"
+trait Trait { fn m(); }
+
+fn foo() { let _ = Trait::<|> }
+"#,
+            expect![[r#"
+                fn m() fn m()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_trait_associated_method_2() {
+        check(
+            r#"
+trait Trait { fn m(); }
+
+struct S;
+impl Trait for S {}
+
+fn foo() { let _ = S::<|> }
+"#,
+            expect![[r#"
+                fn m() fn m()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_trait_associated_method_3() {
+        check(
+            r#"
+trait Trait { fn m(); }
+
+struct S;
+impl Trait for S {}
+
+fn foo() { let _ = <S as Trait>::<|> }
+"#,
+            expect![[r#"
+                fn m() fn m()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_ty_param_assoc_ty() {
+        check(
+            r#"
+trait Super {
+    type Ty;
+    const CONST: u8;
+    fn func() {}
+    fn method(&self) {}
+}
+
+trait Sub: Super {
+    type SubTy;
+    const C2: ();
+    fn subfunc() {}
+    fn submethod(&self) {}
+}
+
+fn foo<T: Sub>() { T::<|> }
+"#,
+            expect![[r#"
+                ct C2          const C2: ();
+                ct CONST       const CONST: u8;
+                ta SubTy       type SubTy;
+                ta Ty          type Ty;
+                fn func()      fn func()
+                me method()    fn method(&self)
+                fn subfunc()   fn subfunc()
+                me submethod() fn submethod(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_self_param_assoc_ty() {
+        check(
+            r#"
+trait Super {
+    type Ty;
+    const CONST: u8 = 0;
+    fn func() {}
+    fn method(&self) {}
+}
+
+trait Sub: Super {
+    type SubTy;
+    const C2: () = ();
+    fn subfunc() {}
+    fn submethod(&self) {}
+}
+
+struct Wrap<T>(T);
+impl<T> Super for Wrap<T> {}
+impl<T> Sub for Wrap<T> {
+    fn subfunc() {
+        // Should be able to assume `Self: Sub + Super`
+        Self::<|>
+    }
+}
+"#,
+            expect![[r#"
+                ct C2          const C2: () = ();
+                ct CONST       const CONST: u8 = 0;
+                ta SubTy       type SubTy;
+                ta Ty          type Ty;
+                fn func()      fn func()
+                me method()    fn method(&self)
+                fn subfunc()   fn subfunc()
+                me submethod() fn submethod(&self)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_type_alias() {
+        check(
+            r#"
+struct S;
+impl S { fn foo() {} }
+type T = S;
+impl T { fn bar() {} }
+
+fn main() { T::<|>; }
+"#,
+            expect![[r#"
+                fn bar() fn bar()
+                fn foo() fn foo()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_qualified_macros() {
+        check(
+            r#"
+#[macro_export]
+macro_rules! foo { () => {} }
+
+fn main() { let _ = crate::<|> }
+        "#,
+            expect![[r##"
+                ma foo!(…) #[macro_export]
+                macro_rules! foo
+                fn main()  fn main()
+            "##]],
+        );
+    }
+
+    #[test]
+    fn test_super_super_completion() {
+        check(
+            r#"
+mod a {
+    const A: usize = 0;
+    mod b {
+        const B: usize = 0;
+        mod c { use super::super::<|> }
+    }
+}
+"#,
+            expect![[r#"
+                ct A
+                md b
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_reexported_items_under_correct_name() {
+        check(
+            r#"
+fn foo() { self::m::<|> }
+
+mod m {
+    pub use super::p::wrong_fn as right_fn;
+    pub use super::p::WRONG_CONST as RIGHT_CONST;
+    pub use super::p::WrongType as RightType;
+}
+mod p {
+    fn wrong_fn() {}
+    const WRONG_CONST: u32 = 1;
+    struct WrongType {};
+}
+"#,
+            expect![[r#"
+                ct RIGHT_CONST
+                st RightType
+                fn right_fn()  fn wrong_fn()
+            "#]],
+        );
+
+        check_edit(
+            "RightType",
+            r#"
+fn foo() { self::m::<|> }
+
+mod m {
+    pub use super::p::wrong_fn as right_fn;
+    pub use super::p::WRONG_CONST as RIGHT_CONST;
+    pub use super::p::WrongType as RightType;
+}
+mod p {
+    fn wrong_fn() {}
+    const WRONG_CONST: u32 = 1;
+    struct WrongType {};
+}
+"#,
+            r#"
+fn foo() { self::m::RightType }
+
+mod m {
+    pub use super::p::wrong_fn as right_fn;
+    pub use super::p::WRONG_CONST as RIGHT_CONST;
+    pub use super::p::WrongType as RightType;
+}
+mod p {
+    fn wrong_fn() {}
+    const WRONG_CONST: u32 = 1;
+    struct WrongType {};
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+fn main() { m!(self::f<|>); }
+fn foo() {}
+"#,
+            expect![[r#"
+                fn foo()  fn foo()
+                fn main() fn main()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn function_mod_share_name() {
+        check(
+            r#"
+fn foo() { self::m::<|> }
+
+mod m {
+    pub mod z {}
+    pub fn z() {}
+}
+"#,
+            expect![[r#"
+                md z
+                fn z() pub fn z()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_hashmap_new() {
+        check(
+            r#"
+struct RandomState;
+struct HashMap<K, V, S = RandomState> {}
+
+impl<K, V> HashMap<K, V, RandomState> {
+    pub fn new() -> HashMap<K, V, RandomState> { }
+}
+fn foo() {
+    HashMap::<|>
+}
+"#,
+            expect![[r#"
+                fn new() pub fn new() -> HashMap<K, V, RandomState>
+            "#]],
+        );
+    }
+
+    #[test]
+    fn dont_complete_attr() {
+        check(
+            r#"
+mod foo { pub struct Foo; }
+#[foo::<|>]
+fn f() {}
+"#,
+            expect![[""]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_record.rs b/crates/ide/src/completion/complete_record.rs
new file mode 100644
index 000000000..ceb8d16c1
--- /dev/null
+++ b/crates/ide/src/completion/complete_record.rs
@@ -0,0 +1,226 @@
+//! Complete fields in record literals and patterns.
+use crate::completion::{CompletionContext, Completions};
+
+pub(super) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
+    let missing_fields = match (ctx.record_pat_syntax.as_ref(), ctx.record_lit_syntax.as_ref()) {
+        (None, None) => return None,
+        (Some(_), Some(_)) => unreachable!("A record cannot be both a literal and a pattern"),
+        (Some(record_pat), _) => ctx.sema.record_pattern_missing_fields(record_pat),
+        (_, Some(record_lit)) => ctx.sema.record_literal_missing_fields(record_lit),
+    };
+
+    for (field, ty) in missing_fields {
+        acc.add_field(ctx, field, &ty)
+    }
+
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn test_record_pattern_field() {
+        check(
+            r#"
+struct S { foo: u32 }
+
+fn process(f: S) {
+    match f {
+        S { f<|>: 92 } => (),
+    }
+}
+"#,
+            expect![[r#"
+                fd foo u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_pattern_enum_variant() {
+        check(
+            r#"
+enum E { S { foo: u32, bar: () } }
+
+fn process(e: E) {
+    match e {
+        E::S { <|> } => (),
+    }
+}
+"#,
+            expect![[r#"
+                fd bar ()
+                fd foo u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_pattern_field_in_simple_macro() {
+        check(
+            r"
+macro_rules! m { ($e:expr) => { $e } }
+struct S { foo: u32 }
+
+fn process(f: S) {
+    m!(match f {
+        S { f<|>: 92 } => (),
+    })
+}
+",
+            expect![[r#"
+                fd foo u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn only_missing_fields_are_completed_in_destruct_pats() {
+        check(
+            r#"
+struct S {
+    foo1: u32, foo2: u32,
+    bar: u32, baz: u32,
+}
+
+fn main() {
+    let s = S {
+        foo1: 1, foo2: 2,
+        bar: 3, baz: 4,
+    };
+    if let S { foo1, foo2: a, <|> } = s {}
+}
+"#,
+            expect![[r#"
+                fd bar u32
+                fd baz u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_literal_field() {
+        check(
+            r#"
+struct A { the_field: u32 }
+fn foo() {
+   A { the<|> }
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_literal_enum_variant() {
+        check(
+            r#"
+enum E { A { a: u32 } }
+fn foo() {
+    let _ = E::A { <|> }
+}
+"#,
+            expect![[r#"
+                fd a u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_literal_two_structs() {
+        check(
+            r#"
+struct A { a: u32 }
+struct B { b: u32 }
+
+fn foo() {
+   let _: A = B { <|> }
+}
+"#,
+            expect![[r#"
+                fd b u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_literal_generic_struct() {
+        check(
+            r#"
+struct A<T> { a: T }
+
+fn foo() {
+   let _: A<u32> = A { <|> }
+}
+"#,
+            expect![[r#"
+                fd a u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_record_literal_field_in_simple_macro() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+struct A { the_field: u32 }
+fn foo() {
+   m!(A { the<|> })
+}
+"#,
+            expect![[r#"
+                fd the_field u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn only_missing_fields_are_completed() {
+        check(
+            r#"
+struct S {
+    foo1: u32, foo2: u32,
+    bar: u32, baz: u32,
+}
+
+fn main() {
+    let foo1 = 1;
+    let s = S { foo1, foo2: 5, <|> }
+}
+"#,
+            expect![[r#"
+                fd bar u32
+                fd baz u32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_functional_update() {
+        check(
+            r#"
+struct S { foo1: u32, foo2: u32 }
+
+fn main() {
+    let foo1 = 1;
+    let s = S { foo1, <|> .. loop {} }
+}
+"#,
+            expect![[r#"
+                fd foo2 u32
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_snippet.rs b/crates/ide/src/completion/complete_snippet.rs
new file mode 100644
index 000000000..c3b03b199
--- /dev/null
+++ b/crates/ide/src/completion/complete_snippet.rs
@@ -0,0 +1,116 @@
+//! FIXME: write short doc here
+
+use crate::completion::{
+    completion_config::SnippetCap, completion_item::Builder, CompletionContext, CompletionItem,
+    CompletionItemKind, CompletionKind, Completions,
+};
+
+fn snippet(ctx: &CompletionContext, cap: SnippetCap, label: &str, snippet: &str) -> Builder {
+    CompletionItem::new(CompletionKind::Snippet, ctx.source_range(), label)
+        .insert_snippet(cap, snippet)
+        .kind(CompletionItemKind::Snippet)
+}
+
+pub(super) fn complete_expr_snippet(acc: &mut Completions, ctx: &CompletionContext) {
+    if !(ctx.is_trivial_path && ctx.function_syntax.is_some()) {
+        return;
+    }
+    let cap = match ctx.config.snippet_cap {
+        Some(it) => it,
+        None => return,
+    };
+
+    snippet(ctx, cap, "pd", "eprintln!(\"$0 = {:?}\", $0);").add_to(acc);
+    snippet(ctx, cap, "ppd", "eprintln!(\"$0 = {:#?}\", $0);").add_to(acc);
+}
+
+pub(super) fn complete_item_snippet(acc: &mut Completions, ctx: &CompletionContext) {
+    if !ctx.is_new_item {
+        return;
+    }
+    let cap = match ctx.config.snippet_cap {
+        Some(it) => it,
+        None => return,
+    };
+
+    snippet(
+        ctx,
+        cap,
+        "tmod (Test module)",
+        "\
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn ${1:test_name}() {
+        $0
+    }
+}",
+    )
+    .lookup_by("tmod")
+    .add_to(acc);
+
+    snippet(
+        ctx,
+        cap,
+        "tfn (Test function)",
+        "\
+#[test]
+fn ${1:feature}() {
+    $0
+}",
+    )
+    .lookup_by("tfn")
+    .add_to(acc);
+
+    snippet(ctx, cap, "macro_rules", "macro_rules! $1 {\n\t($2) => {\n\t\t$0\n\t};\n}").add_to(acc);
+    snippet(ctx, cap, "pub(crate)", "pub(crate) $0").add_to(acc);
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{test_utils::completion_list, CompletionKind};
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Snippet);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn completes_snippets_in_expressions() {
+        check(
+            r#"fn foo(x: i32) { <|> }"#,
+            expect![[r#"
+                sn pd
+                sn ppd
+            "#]],
+        );
+    }
+
+    #[test]
+    fn should_not_complete_snippets_in_path() {
+        check(r#"fn foo(x: i32) { ::foo<|> }"#, expect![[""]]);
+        check(r#"fn foo(x: i32) { ::<|> }"#, expect![[""]]);
+    }
+
+    #[test]
+    fn completes_snippets_in_items() {
+        check(
+            r#"
+#[cfg(test)]
+mod tests {
+    <|>
+}
+"#,
+            expect![[r#"
+                sn macro_rules
+                sn pub(crate)
+                sn tfn (Test function)
+                sn tmod (Test module)
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion/complete_trait_impl.rs b/crates/ide/src/completion/complete_trait_impl.rs
new file mode 100644
index 000000000..1a2b1e8a5
--- /dev/null
+++ b/crates/ide/src/completion/complete_trait_impl.rs
@@ -0,0 +1,488 @@
+//! Completion for associated items in a trait implementation.
+//!
+//! This module adds the completion items related to implementing associated
+//! items within a `impl Trait for Struct` block. The current context node
+//! must be within either a `FN`, `TYPE_ALIAS`, or `CONST` node
+//! and an direct child of an `IMPL`.
+//!
+//! # Examples
+//!
+//! Considering the following trait `impl`:
+//!
+//! ```ignore
+//! trait SomeTrait {
+//!     fn foo();
+//! }
+//!
+//! impl SomeTrait for () {
+//!     fn f<|>
+//! }
+//! ```
+//!
+//! may result in the completion of the following method:
+//!
+//! ```ignore
+//! # trait SomeTrait {
+//! #    fn foo();
+//! # }
+//!
+//! impl SomeTrait for () {
+//!     fn foo() {}<|>
+//! }
+//! ```
+
+use assists::utils::get_missing_assoc_items;
+use hir::{self, Docs, HasSource};
+use syntax::{
+    ast::{self, edit, Impl},
+    AstNode, SyntaxKind, SyntaxNode, TextRange, T,
+};
+use text_edit::TextEdit;
+
+use crate::{
+    completion::{
+        CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions,
+    },
+    display::function_declaration,
+};
+
+pub(crate) fn complete_trait_impl(acc: &mut Completions, ctx: &CompletionContext) {
+    if let Some((trigger, impl_def)) = completion_match(ctx) {
+        match trigger.kind() {
+            SyntaxKind::NAME_REF => get_missing_assoc_items(&ctx.sema, &impl_def)
+                .into_iter()
+                .for_each(|item| match item {
+                    hir::AssocItem::Function(fn_item) => {
+                        add_function_impl(&trigger, acc, ctx, fn_item)
+                    }
+                    hir::AssocItem::TypeAlias(type_item) => {
+                        add_type_alias_impl(&trigger, acc, ctx, type_item)
+                    }
+                    hir::AssocItem::Const(const_item) => {
+                        add_const_impl(&trigger, acc, ctx, const_item)
+                    }
+                }),
+
+            SyntaxKind::FN => {
+                for missing_fn in get_missing_assoc_items(&ctx.sema, &impl_def)
+                    .into_iter()
+                    .filter_map(|item| match item {
+                        hir::AssocItem::Function(fn_item) => Some(fn_item),
+                        _ => None,
+                    })
+                {
+                    add_function_impl(&trigger, acc, ctx, missing_fn);
+                }
+            }
+
+            SyntaxKind::TYPE_ALIAS => {
+                for missing_fn in get_missing_assoc_items(&ctx.sema, &impl_def)
+                    .into_iter()
+                    .filter_map(|item| match item {
+                        hir::AssocItem::TypeAlias(type_item) => Some(type_item),
+                        _ => None,
+                    })
+                {
+                    add_type_alias_impl(&trigger, acc, ctx, missing_fn);
+                }
+            }
+
+            SyntaxKind::CONST => {
+                for missing_fn in get_missing_assoc_items(&ctx.sema, &impl_def)
+                    .into_iter()
+                    .filter_map(|item| match item {
+                        hir::AssocItem::Const(const_item) => Some(const_item),
+                        _ => None,
+                    })
+                {
+                    add_const_impl(&trigger, acc, ctx, missing_fn);
+                }
+            }
+
+            _ => {}
+        }
+    }
+}
+
+fn completion_match(ctx: &CompletionContext) -> Option<(SyntaxNode, Impl)> {
+    let (trigger, impl_def_offset) = ctx.token.ancestors().find_map(|p| match p.kind() {
+        SyntaxKind::FN | SyntaxKind::TYPE_ALIAS | SyntaxKind::CONST | SyntaxKind::BLOCK_EXPR => {
+            Some((p, 2))
+        }
+        SyntaxKind::NAME_REF => Some((p, 5)),
+        _ => None,
+    })?;
+    let impl_def = (0..impl_def_offset - 1)
+        .try_fold(trigger.parent()?, |t, _| t.parent())
+        .and_then(ast::Impl::cast)?;
+    Some((trigger, impl_def))
+}
+
+fn add_function_impl(
+    fn_def_node: &SyntaxNode,
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    func: hir::Function,
+) {
+    let fn_name = func.name(ctx.db).to_string();
+
+    let label = if func.params(ctx.db).is_empty() {
+        format!("fn {}()", fn_name)
+    } else {
+        format!("fn {}(..)", fn_name)
+    };
+
+    let builder = CompletionItem::new(CompletionKind::Magic, ctx.source_range(), label)
+        .lookup_by(fn_name)
+        .set_documentation(func.docs(ctx.db));
+
+    let completion_kind = if func.self_param(ctx.db).is_some() {
+        CompletionItemKind::Method
+    } else {
+        CompletionItemKind::Function
+    };
+    let range = TextRange::new(fn_def_node.text_range().start(), ctx.source_range().end());
+
+    let function_decl = function_declaration(&func.source(ctx.db).value);
+    match ctx.config.snippet_cap {
+        Some(cap) => {
+            let snippet = format!("{} {{\n    $0\n}}", function_decl);
+            builder.snippet_edit(cap, TextEdit::replace(range, snippet))
+        }
+        None => {
+            let header = format!("{} {{", function_decl);
+            builder.text_edit(TextEdit::replace(range, header))
+        }
+    }
+    .kind(completion_kind)
+    .add_to(acc);
+}
+
+fn add_type_alias_impl(
+    type_def_node: &SyntaxNode,
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    type_alias: hir::TypeAlias,
+) {
+    let alias_name = type_alias.name(ctx.db).to_string();
+
+    let snippet = format!("type {} = ", alias_name);
+
+    let range = TextRange::new(type_def_node.text_range().start(), ctx.source_range().end());
+
+    CompletionItem::new(CompletionKind::Magic, ctx.source_range(), snippet.clone())
+        .text_edit(TextEdit::replace(range, snippet))
+        .lookup_by(alias_name)
+        .kind(CompletionItemKind::TypeAlias)
+        .set_documentation(type_alias.docs(ctx.db))
+        .add_to(acc);
+}
+
+fn add_const_impl(
+    const_def_node: &SyntaxNode,
+    acc: &mut Completions,
+    ctx: &CompletionContext,
+    const_: hir::Const,
+) {
+    let const_name = const_.name(ctx.db).map(|n| n.to_string());
+
+    if let Some(const_name) = const_name {
+        let snippet = make_const_compl_syntax(&const_.source(ctx.db).value);
+
+        let range = TextRange::new(const_def_node.text_range().start(), ctx.source_range().end());
+
+        CompletionItem::new(CompletionKind::Magic, ctx.source_range(), snippet.clone())
+            .text_edit(TextEdit::replace(range, snippet))
+            .lookup_by(const_name)
+            .kind(CompletionItemKind::Const)
+            .set_documentation(const_.docs(ctx.db))
+            .add_to(acc);
+    }
+}
+
+fn make_const_compl_syntax(const_: &ast::Const) -> String {
+    let const_ = edit::remove_attrs_and_docs(const_);
+
+    let const_start = const_.syntax().text_range().start();
+    let const_end = const_.syntax().text_range().end();
+
+    let start =
+        const_.syntax().first_child_or_token().map_or(const_start, |f| f.text_range().start());
+
+    let end = const_
+        .syntax()
+        .children_with_tokens()
+        .find(|s| s.kind() == T![;] || s.kind() == T![=])
+        .map_or(const_end, |f| f.text_range().start());
+
+    let len = end - start;
+    let range = TextRange::new(0.into(), len);
+
+    let syntax = const_.syntax().text().slice(range).to_string();
+
+    format!("{} = ", syntax.trim_end())
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::completion::{
+        test_utils::{check_edit, completion_list},
+        CompletionKind,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Magic);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn name_ref_function_type_const() {
+        check(
+            r#"
+trait Test {
+    type TestType;
+    const TEST_CONST: u16;
+    fn test();
+}
+struct T;
+
+impl Test for T {
+    t<|>
+}
+"#,
+            expect![["
+ct const TEST_CONST: u16 = \n\
+fn fn test()
+ta type TestType = \n\
+            "]],
+        );
+    }
+
+    #[test]
+    fn no_nested_fn_completions() {
+        check(
+            r"
+trait Test {
+    fn test();
+    fn test2();
+}
+struct T;
+
+impl Test for T {
+    fn test() {
+        t<|>
+    }
+}
+",
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn name_ref_single_function() {
+        check_edit(
+            "test",
+            r#"
+trait Test {
+    fn test();
+}
+struct T;
+
+impl Test for T {
+    t<|>
+}
+"#,
+            r#"
+trait Test {
+    fn test();
+}
+struct T;
+
+impl Test for T {
+    fn test() {
+    $0
+}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn single_function() {
+        check_edit(
+            "test",
+            r#"
+trait Test {
+    fn test();
+}
+struct T;
+
+impl Test for T {
+    fn t<|>
+}
+"#,
+            r#"
+trait Test {
+    fn test();
+}
+struct T;
+
+impl Test for T {
+    fn test() {
+    $0
+}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn hide_implemented_fn() {
+        check(
+            r#"
+trait Test {
+    fn foo();
+    fn foo_bar();
+}
+struct T;
+
+impl Test for T {
+    fn foo() {}
+    fn f<|>
+}
+"#,
+            expect![[r#"
+                fn fn foo_bar()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn generic_fn() {
+        check_edit(
+            "foo",
+            r#"
+trait Test {
+    fn foo<T>();
+}
+struct T;
+
+impl Test for T {
+    fn f<|>
+}
+"#,
+            r#"
+trait Test {
+    fn foo<T>();
+}
+struct T;
+
+impl Test for T {
+    fn foo<T>() {
+    $0
+}
+}
+"#,
+        );
+        check_edit(
+            "foo",
+            r#"
+trait Test {
+    fn foo<T>() where T: Into<String>;
+}
+struct T;
+
+impl Test for T {
+    fn f<|>
+}
+"#,
+            r#"
+trait Test {
+    fn foo<T>() where T: Into<String>;
+}
+struct T;
+
+impl Test for T {
+    fn foo<T>()
+where T: Into<String> {
+    $0
+}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn associated_type() {
+        check_edit(
+            "SomeType",
+            r#"
+trait Test {
+    type SomeType;
+}
+
+impl Test for () {
+    type S<|>
+}
+"#,
+            "
+trait Test {
+    type SomeType;
+}
+
+impl Test for () {
+    type SomeType = \n\
+}
+",
+        );
+    }
+
+    #[test]
+    fn associated_const() {
+        check_edit(
+            "SOME_CONST",
+            r#"
+trait Test {
+    const SOME_CONST: u16;
+}
+
+impl Test for () {
+    const S<|>
+}
+"#,
+            "
+trait Test {
+    const SOME_CONST: u16;
+}
+
+impl Test for () {
+    const SOME_CONST: u16 = \n\
+}
+",
+        );
+
+        check_edit(
+            "SOME_CONST",
+            r#"
+trait Test {
+    const SOME_CONST: u16 = 92;
+}
+
+impl Test for () {
+    const S<|>
+}
+"#,
+            "
+trait Test {
+    const SOME_CONST: u16 = 92;
+}
+
+impl Test for () {
+    const SOME_CONST: u16 = \n\
+}
+",
+        );
+    }
+}
diff --git a/crates/ide/src/completion/complete_unqualified_path.rs b/crates/ide/src/completion/complete_unqualified_path.rs
new file mode 100644
index 000000000..1f1b682a7
--- /dev/null
+++ b/crates/ide/src/completion/complete_unqualified_path.rs
@@ -0,0 +1,658 @@
+//! Completion of names from the current scope, e.g. locals and imported items.
+
+use hir::{Adt, ModuleDef, ScopeDef, Type};
+use syntax::AstNode;
+use test_utils::mark;
+
+use crate::completion::{CompletionContext, Completions};
+
+pub(super) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionContext) {
+    if !(ctx.is_trivial_path || ctx.is_pat_binding_or_const) {
+        return;
+    }
+    if ctx.record_lit_syntax.is_some()
+        || ctx.record_pat_syntax.is_some()
+        || ctx.attribute_under_caret.is_some()
+    {
+        return;
+    }
+
+    if let Some(ty) = &ctx.expected_type {
+        complete_enum_variants(acc, ctx, ty);
+    }
+
+    if ctx.is_pat_binding_or_const {
+        return;
+    }
+
+    ctx.scope.process_all_names(&mut |name, res| {
+        if ctx.use_item_syntax.is_some() {
+            if let (ScopeDef::Unknown, Some(name_ref)) = (&res, &ctx.name_ref_syntax) {
+                if name_ref.syntax().text() == name.to_string().as_str() {
+                    mark::hit!(self_fulfilling_completion);
+                    return;
+                }
+            }
+        }
+        acc.add_resolution(ctx, name.to_string(), &res)
+    });
+}
+
+fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &Type) {
+    if let Some(Adt::Enum(enum_data)) = ty.as_adt() {
+        let variants = enum_data.variants(ctx.db);
+
+        let module = if let Some(module) = ctx.scope.module() {
+            // Compute path from the completion site if available.
+            module
+        } else {
+            // Otherwise fall back to the enum's definition site.
+            enum_data.module(ctx.db)
+        };
+
+        for variant in variants {
+            if let Some(path) = module.find_use_path(ctx.db, ModuleDef::from(variant)) {
+                // Variants with trivial paths are already added by the existing completion logic,
+                // so we should avoid adding these twice
+                if path.segments.len() > 1 {
+                    acc.add_qualified_enum_variant(ctx, variant, path);
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use test_utils::mark;
+
+    use crate::completion::{
+        test_utils::{check_edit, completion_list},
+        CompletionKind,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = completion_list(ra_fixture, CompletionKind::Reference);
+        expect.assert_eq(&actual)
+    }
+
+    #[test]
+    fn self_fulfilling_completion() {
+        mark::check!(self_fulfilling_completion);
+        check(
+            r#"
+use foo<|>
+use std::collections;
+"#,
+            expect![[r#"
+                ?? collections
+            "#]],
+        );
+    }
+
+    #[test]
+    fn bind_pat_and_path_ignore_at() {
+        check(
+            r#"
+enum Enum { A, B }
+fn quux(x: Option<Enum>) {
+    match x {
+        None => (),
+        Some(en<|> @ Enum::A) => (),
+    }
+}
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn bind_pat_and_path_ignore_ref() {
+        check(
+            r#"
+enum Enum { A, B }
+fn quux(x: Option<Enum>) {
+    match x {
+        None => (),
+        Some(ref en<|>) => (),
+    }
+}
+"#,
+            expect![[""]],
+        );
+    }
+
+    #[test]
+    fn bind_pat_and_path() {
+        check(
+            r#"
+enum Enum { A, B }
+fn quux(x: Option<Enum>) {
+    match x {
+        None => (),
+        Some(En<|>) => (),
+    }
+}
+"#,
+            expect![[r#"
+                en Enum
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_bindings_from_let() {
+        check(
+            r#"
+fn quux(x: i32) {
+    let y = 92;
+    1 + <|>;
+    let z = ();
+}
+"#,
+            expect![[r#"
+                fn quux(…) fn quux(x: i32)
+                bn x       i32
+                bn y       i32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_bindings_from_if_let() {
+        check(
+            r#"
+fn quux() {
+    if let Some(x) = foo() {
+        let y = 92;
+    };
+    if let Some(a) = bar() {
+        let b = 62;
+        1 + <|>
+    }
+}
+"#,
+            expect![[r#"
+                bn a
+                bn b      i32
+                fn quux() fn quux()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_bindings_from_for() {
+        check(
+            r#"
+fn quux() {
+    for x in &[1, 2, 3] { <|> }
+}
+"#,
+            expect![[r#"
+                fn quux() fn quux()
+                bn x
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_if_prefix_is_keyword() {
+        mark::check!(completes_if_prefix_is_keyword);
+        check_edit(
+            "wherewolf",
+            r#"
+fn main() {
+    let wherewolf = 92;
+    drop(where<|>)
+}
+"#,
+            r#"
+fn main() {
+    let wherewolf = 92;
+    drop(wherewolf)
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn completes_generic_params() {
+        check(
+            r#"fn quux<T>() { <|> }"#,
+            expect![[r#"
+                tp T
+                fn quux() fn quux<T>()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_generic_params_in_struct() {
+        check(
+            r#"struct S<T> { x: <|>}"#,
+            expect![[r#"
+                st S<…>
+                tp Self
+                tp T
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_self_in_enum() {
+        check(
+            r#"enum X { Y(<|>) }"#,
+            expect![[r#"
+                tp Self
+                en X
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_module_items() {
+        check(
+            r#"
+struct S;
+enum E {}
+fn quux() { <|> }
+"#,
+            expect![[r#"
+                en E
+                st S
+                fn quux() fn quux()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_extern_prelude() {
+        check(
+            r#"
+//- /lib.rs
+use <|>;
+
+//- /other_crate/lib.rs
+// nothing here
+"#,
+            expect![[r#"
+                md other_crate
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_module_items_in_nested_modules() {
+        check(
+            r#"
+struct Foo;
+mod m {
+    struct Bar;
+    fn quux() { <|> }
+}
+"#,
+            expect![[r#"
+                st Bar
+                fn quux() fn quux()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_return_type() {
+        check(
+            r#"
+struct Foo;
+fn x() -> <|>
+"#,
+            expect![[r#"
+                st Foo
+                fn x() fn x()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn dont_show_both_completions_for_shadowing() {
+        check(
+            r#"
+fn foo() {
+    let bar = 92;
+    {
+        let bar = 62;
+        drop(<|>)
+    }
+}
+"#,
+            // FIXME: should be only one bar here
+            expect![[r#"
+                bn bar   i32
+                bn bar   i32
+                fn foo() fn foo()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_self_in_methods() {
+        check(
+            r#"impl S { fn foo(&self) { <|> } }"#,
+            expect![[r#"
+                tp Self
+                bn self &{unknown}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_prelude() {
+        check(
+            r#"
+//- /main.rs
+fn foo() { let x: <|> }
+
+//- /std/lib.rs
+#[prelude_import]
+use prelude::*;
+
+mod prelude { struct Option; }
+"#,
+            expect![[r#"
+                st Option
+                fn foo()  fn foo()
+                md std
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_std_prelude_if_core_is_defined() {
+        check(
+            r#"
+//- /main.rs
+fn foo() { let x: <|> }
+
+//- /core/lib.rs
+#[prelude_import]
+use prelude::*;
+
+mod prelude { struct Option; }
+
+//- /std/lib.rs
+#[prelude_import]
+use prelude::*;
+
+mod prelude { struct String; }
+"#,
+            expect![[r#"
+                st String
+                md core
+                fn foo()  fn foo()
+                md std
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_macros_as_value() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+
+#[macro_use]
+mod m1 {
+    macro_rules! bar { () => {} }
+}
+
+mod m2 {
+    macro_rules! nope { () => {} }
+
+    #[macro_export]
+    macro_rules! baz { () => {} }
+}
+
+fn main() { let v = <|> }
+"#,
+            expect![[r##"
+                ma bar!(…) macro_rules! bar
+                ma baz!(…) #[macro_export]
+                macro_rules! baz
+                ma foo!(…) macro_rules! foo
+                md m1
+                md m2
+                fn main()  fn main()
+            "##]],
+        );
+    }
+
+    #[test]
+    fn completes_both_macro_and_value() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+fn foo() { <|> }
+"#,
+            expect![[r#"
+                ma foo!(…) macro_rules! foo
+                fn foo()   fn foo()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_macros_as_type() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+fn main() { let x: <|> }
+"#,
+            expect![[r#"
+                ma foo!(…) macro_rules! foo
+                fn main()  fn main()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_macros_as_stmt() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+fn main() { <|> }
+"#,
+            expect![[r#"
+                ma foo!(…) macro_rules! foo
+                fn main()  fn main()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_local_item() {
+        check(
+            r#"
+fn main() {
+    return f<|>;
+    fn frobnicate() {}
+}
+"#,
+            expect![[r#"
+                fn frobnicate() fn frobnicate()
+                fn main()       fn main()
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_1() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+fn quux(x: i32) {
+    let y = 92;
+    m!(<|>);
+}
+"#,
+            expect![[r#"
+                ma m!(…)   macro_rules! m
+                fn quux(…) fn quux(x: i32)
+                bn x       i32
+                bn y       i32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_2() {
+        check(
+            r"
+macro_rules! m { ($e:expr) => { $e } }
+fn quux(x: i32) {
+    let y = 92;
+    m!(x<|>);
+}
+",
+            expect![[r#"
+                ma m!(…)   macro_rules! m
+                fn quux(…) fn quux(x: i32)
+                bn x       i32
+                bn y       i32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_in_simple_macro_without_closing_parens() {
+        check(
+            r#"
+macro_rules! m { ($e:expr) => { $e } }
+fn quux(x: i32) {
+    let y = 92;
+    m!(x<|>
+}
+"#,
+            expect![[r#"
+                ma m!(…)   macro_rules! m
+                fn quux(…) fn quux(x: i32)
+                bn x       i32
+                bn y       i32
+            "#]],
+        );
+    }
+
+    #[test]
+    fn completes_unresolved_uses() {
+        check(
+            r#"
+use spam::Quux;
+
+fn main() { <|> }
+"#,
+            expect![[r#"
+                ?? Quux
+                fn main() fn main()
+            "#]],
+        );
+    }
+    #[test]
+    fn completes_enum_variant_matcharm() {
+        check(
+            r#"
+enum Foo { Bar, Baz, Quux }
+
+fn main() {
+    let foo = Foo::Quux;
+    match foo { Qu<|> }
+}
+"#,
+            expect![[r#"
+                en Foo
+                ev Foo::Bar  ()
+                ev Foo::Baz  ()
+                ev Foo::Quux ()
+            "#]],
+        )
+    }
+
+    #[test]
+    fn completes_enum_variant_iflet() {
+        check(
+            r#"
+enum Foo { Bar, Baz, Quux }
+
+fn main() {
+    let foo = Foo::Quux;
+    if let Qu<|> = foo { }
+}
+"#,
+            expect![[r#"
+                en Foo
+                ev Foo::Bar  ()
+                ev Foo::Baz  ()
+                ev Foo::Quux ()
+            "#]],
+        )
+    }
+
+    #[test]
+    fn completes_enum_variant_basic_expr() {
+        check(
+            r#"
+enum Foo { Bar, Baz, Quux }
+fn main() { let foo: Foo = Q<|> }
+"#,
+            expect![[r#"
+                en Foo
+                ev Foo::Bar  ()
+                ev Foo::Baz  ()
+                ev Foo::Quux ()
+                fn main()    fn main()
+            "#]],
+        )
+    }
+
+    #[test]
+    fn completes_enum_variant_from_module() {
+        check(
+            r#"
+mod m { pub enum E { V } }
+fn f() -> m::E { V<|> }
+"#,
+            expect![[r#"
+                fn f()     fn f() -> m::E
+                md m
+                ev m::E::V ()
+            "#]],
+        )
+    }
+
+    #[test]
+    fn dont_complete_attr() {
+        check(
+            r#"
+struct Foo;
+#[<|>]
+fn f() {}
+"#,
+            expect![[""]],
+        )
+    }
+
+    #[test]
+    fn completes_type_or_trait_in_impl_block() {
+        check(
+            r#"
+trait MyTrait {}
+struct MyStruct {}
+
+impl My<|>
+"#,
+            expect![[r#"
+                st MyStruct
+                tt MyTrait
+                tp Self
+            "#]],
+        )
+    }
+}
diff --git a/crates/ide/src/completion/completion_config.rs b/crates/ide/src/completion/completion_config.rs
new file mode 100644
index 000000000..71b49ace8
--- /dev/null
+++ b/crates/ide/src/completion/completion_config.rs
@@ -0,0 +1,35 @@
+//! Settings for tweaking completion.
+//!
+//! The fun thing here is `SnippetCap` -- this type can only be created in this
+//! module, and we use to statically check that we only produce snippet
+//! completions if we are allowed to.
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CompletionConfig {
+    pub enable_postfix_completions: bool,
+    pub add_call_parenthesis: bool,
+    pub add_call_argument_snippets: bool,
+    pub snippet_cap: Option<SnippetCap>,
+}
+
+impl CompletionConfig {
+    pub fn allow_snippets(&mut self, yes: bool) {
+        self.snippet_cap = if yes { Some(SnippetCap { _private: () }) } else { None }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SnippetCap {
+    _private: (),
+}
+
+impl Default for CompletionConfig {
+    fn default() -> Self {
+        CompletionConfig {
+            enable_postfix_completions: true,
+            add_call_parenthesis: true,
+            add_call_argument_snippets: true,
+            snippet_cap: Some(SnippetCap { _private: () }),
+        }
+    }
+}
diff --git a/crates/ide/src/completion/completion_context.rs b/crates/ide/src/completion/completion_context.rs
new file mode 100644
index 000000000..5adac7ebc
--- /dev/null
+++ b/crates/ide/src/completion/completion_context.rs
@@ -0,0 +1,486 @@
+//! FIXME: write short doc here
+
+use base_db::SourceDatabase;
+use hir::{Semantics, SemanticsScope, Type};
+use ide_db::RootDatabase;
+use syntax::{
+    algo::{find_covering_element, find_node_at_offset},
+    ast, match_ast, AstNode, NodeOrToken,
+    SyntaxKind::*,
+    SyntaxNode, SyntaxToken, TextRange, TextSize,
+};
+use test_utils::mark;
+use text_edit::Indel;
+
+use crate::{
+    call_info::ActiveParameter,
+    completion::{
+        patterns::{
+            has_bind_pat_parent, has_block_expr_parent, has_impl_as_prev_sibling, has_impl_parent,
+            has_item_list_or_source_file_parent, has_ref_parent, has_trait_as_prev_sibling,
+            has_trait_parent, if_is_prev, is_in_loop_body, is_match_arm, unsafe_is_prev,
+        },
+        CompletionConfig,
+    },
+    FilePosition,
+};
+
+/// `CompletionContext` is created early during completion to figure out, where
+/// exactly is the cursor, syntax-wise.
+#[derive(Debug)]
+pub(crate) struct CompletionContext<'a> {
+    pub(super) sema: Semantics<'a, RootDatabase>,
+    pub(super) scope: SemanticsScope<'a>,
+    pub(super) db: &'a RootDatabase,
+    pub(super) config: &'a CompletionConfig,
+    pub(super) position: FilePosition,
+    /// The token before the cursor, in the original file.
+    pub(super) original_token: SyntaxToken,
+    /// The token before the cursor, in the macro-expanded file.
+    pub(super) token: SyntaxToken,
+    pub(super) krate: Option<hir::Crate>,
+    pub(super) expected_type: Option<Type>,
+    pub(super) name_ref_syntax: Option<ast::NameRef>,
+    pub(super) function_syntax: Option<ast::Fn>,
+    pub(super) use_item_syntax: Option<ast::Use>,
+    pub(super) record_lit_syntax: Option<ast::RecordExpr>,
+    pub(super) record_pat_syntax: Option<ast::RecordPat>,
+    pub(super) record_field_syntax: Option<ast::RecordExprField>,
+    pub(super) impl_def: Option<ast::Impl>,
+    /// FIXME: `ActiveParameter` is string-based, which is very very wrong
+    pub(super) active_parameter: Option<ActiveParameter>,
+    pub(super) is_param: bool,
+    /// If a name-binding or reference to a const in a pattern.
+    /// Irrefutable patterns (like let) are excluded.
+    pub(super) is_pat_binding_or_const: bool,
+    /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
+    pub(super) is_trivial_path: bool,
+    /// If not a trivial path, the prefix (qualifier).
+    pub(super) path_qual: Option<ast::Path>,
+    pub(super) after_if: bool,
+    /// `true` if we are a statement or a last expr in the block.
+    pub(super) can_be_stmt: bool,
+    /// `true` if we expect an expression at the cursor position.
+    pub(super) is_expr: bool,
+    /// Something is typed at the "top" level, in module or impl/trait.
+    pub(super) is_new_item: bool,
+    /// The receiver if this is a field or method access, i.e. writing something.<|>
+    pub(super) dot_receiver: Option<ast::Expr>,
+    pub(super) dot_receiver_is_ambiguous_float_literal: bool,
+    /// If this is a call (method or function) in particular, i.e. the () are already there.
+    pub(super) is_call: bool,
+    /// Like `is_call`, but for tuple patterns.
+    pub(super) is_pattern_call: bool,
+    /// If this is a macro call, i.e. the () are already there.
+    pub(super) is_macro_call: bool,
+    pub(super) is_path_type: bool,
+    pub(super) has_type_args: bool,
+    pub(super) attribute_under_caret: Option<ast::Attr>,
+    pub(super) unsafe_is_prev: bool,
+    pub(super) if_is_prev: bool,
+    pub(super) block_expr_parent: bool,
+    pub(super) bind_pat_parent: bool,
+    pub(super) ref_pat_parent: bool,
+    pub(super) in_loop_body: bool,
+    pub(super) has_trait_parent: bool,
+    pub(super) has_impl_parent: bool,
+    pub(super) trait_as_prev_sibling: bool,
+    pub(super) impl_as_prev_sibling: bool,
+    pub(super) is_match_arm: bool,
+    pub(super) has_item_list_or_source_file_parent: bool,
+}
+
+impl<'a> CompletionContext<'a> {
+    pub(super) fn new(
+        db: &'a RootDatabase,
+        position: FilePosition,
+        config: &'a CompletionConfig,
+    ) -> Option<CompletionContext<'a>> {
+        let sema = Semantics::new(db);
+
+        let original_file = sema.parse(position.file_id);
+
+        // Insert a fake ident to get a valid parse tree. We will use this file
+        // to determine context, though the original_file will be used for
+        // actual completion.
+        let file_with_fake_ident = {
+            let parse = db.parse(position.file_id);
+            let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
+            parse.reparse(&edit).tree()
+        };
+        let fake_ident_token =
+            file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
+
+        let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
+        let original_token =
+            original_file.syntax().token_at_offset(position.offset).left_biased()?;
+        let token = sema.descend_into_macros(original_token.clone());
+        let scope = sema.scope_at_offset(&token.parent(), position.offset);
+        let mut ctx = CompletionContext {
+            sema,
+            scope,
+            db,
+            config,
+            original_token,
+            token,
+            position,
+            krate,
+            expected_type: None,
+            name_ref_syntax: None,
+            function_syntax: None,
+            use_item_syntax: None,
+            record_lit_syntax: None,
+            record_pat_syntax: None,
+            record_field_syntax: None,
+            impl_def: None,
+            active_parameter: ActiveParameter::at(db, position),
+            is_param: false,
+            is_pat_binding_or_const: false,
+            is_trivial_path: false,
+            path_qual: None,
+            after_if: false,
+            can_be_stmt: false,
+            is_expr: false,
+            is_new_item: false,
+            dot_receiver: None,
+            is_call: false,
+            is_pattern_call: false,
+            is_macro_call: false,
+            is_path_type: false,
+            has_type_args: false,
+            dot_receiver_is_ambiguous_float_literal: false,
+            attribute_under_caret: None,
+            unsafe_is_prev: false,
+            in_loop_body: false,
+            ref_pat_parent: false,
+            bind_pat_parent: false,
+            block_expr_parent: false,
+            has_trait_parent: false,
+            has_impl_parent: false,
+            trait_as_prev_sibling: false,
+            impl_as_prev_sibling: false,
+            if_is_prev: false,
+            is_match_arm: false,
+            has_item_list_or_source_file_parent: false,
+        };
+
+        let mut original_file = original_file.syntax().clone();
+        let mut hypothetical_file = file_with_fake_ident.syntax().clone();
+        let mut offset = position.offset;
+        let mut fake_ident_token = fake_ident_token;
+
+        // Are we inside a macro call?
+        while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
+            find_node_at_offset::<ast::MacroCall>(&original_file, offset),
+            find_node_at_offset::<ast::MacroCall>(&hypothetical_file, offset),
+        ) {
+            if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
+                != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
+            {
+                break;
+            }
+            let hypothetical_args = match macro_call_with_fake_ident.token_tree() {
+                Some(tt) => tt,
+                None => break,
+            };
+            if let (Some(actual_expansion), Some(hypothetical_expansion)) = (
+                ctx.sema.expand(&actual_macro_call),
+                ctx.sema.speculative_expand(
+                    &actual_macro_call,
+                    &hypothetical_args,
+                    fake_ident_token,
+                ),
+            ) {
+                let new_offset = hypothetical_expansion.1.text_range().start();
+                if new_offset > actual_expansion.text_range().end() {
+                    break;
+                }
+                original_file = actual_expansion;
+                hypothetical_file = hypothetical_expansion.0;
+                fake_ident_token = hypothetical_expansion.1;
+                offset = new_offset;
+            } else {
+                break;
+            }
+        }
+        ctx.fill_keyword_patterns(&hypothetical_file, offset);
+        ctx.fill(&original_file, hypothetical_file, offset);
+        Some(ctx)
+    }
+
+    // The range of the identifier that is being completed.
+    pub(crate) fn source_range(&self) -> TextRange {
+        // check kind of macro-expanded token, but use range of original token
+        if self.token.kind() == IDENT || self.token.kind().is_keyword() {
+            mark::hit!(completes_if_prefix_is_keyword);
+            self.original_token.text_range()
+        } else {
+            TextRange::empty(self.position.offset)
+        }
+    }
+
+    fn fill_keyword_patterns(&mut self, file_with_fake_ident: &SyntaxNode, offset: TextSize) {
+        let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
+        let syntax_element = NodeOrToken::Token(fake_ident_token);
+        self.block_expr_parent = has_block_expr_parent(syntax_element.clone());
+        self.unsafe_is_prev = unsafe_is_prev(syntax_element.clone());
+        self.if_is_prev = if_is_prev(syntax_element.clone());
+        self.bind_pat_parent = has_bind_pat_parent(syntax_element.clone());
+        self.ref_pat_parent = has_ref_parent(syntax_element.clone());
+        self.in_loop_body = is_in_loop_body(syntax_element.clone());
+        self.has_trait_parent = has_trait_parent(syntax_element.clone());
+        self.has_impl_parent = has_impl_parent(syntax_element.clone());
+        self.impl_as_prev_sibling = has_impl_as_prev_sibling(syntax_element.clone());
+        self.trait_as_prev_sibling = has_trait_as_prev_sibling(syntax_element.clone());
+        self.is_match_arm = is_match_arm(syntax_element.clone());
+        self.has_item_list_or_source_file_parent =
+            has_item_list_or_source_file_parent(syntax_element);
+    }
+
+    fn fill(
+        &mut self,
+        original_file: &SyntaxNode,
+        file_with_fake_ident: SyntaxNode,
+        offset: TextSize,
+    ) {
+        // FIXME: this is wrong in at least two cases:
+        //  * when there's no token `foo(<|>)`
+        //  * when there is a token, but it happens to have type of it's own
+        self.expected_type = self
+            .token
+            .ancestors()
+            .find_map(|node| {
+                let ty = match_ast! {
+                    match node {
+                        ast::Pat(it) => self.sema.type_of_pat(&it),
+                        ast::Expr(it) => self.sema.type_of_expr(&it),
+                        _ => return None,
+                    }
+                };
+                Some(ty)
+            })
+            .flatten();
+        self.attribute_under_caret = find_node_at_offset(&file_with_fake_ident, offset);
+
+        // First, let's try to complete a reference to some declaration.
+        if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(&file_with_fake_ident, offset) {
+            // Special case, `trait T { fn foo(i_am_a_name_ref) {} }`.
+            // See RFC#1685.
+            if is_node::<ast::Param>(name_ref.syntax()) {
+                self.is_param = true;
+                return;
+            }
+            // FIXME: remove this (V) duplication and make the check more precise
+            if name_ref.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
+                self.record_pat_syntax =
+                    self.sema.find_node_at_offset_with_macros(&original_file, offset);
+            }
+            self.classify_name_ref(original_file, name_ref, offset);
+        }
+
+        // Otherwise, see if this is a declaration. We can use heuristics to
+        // suggest declaration names, see `CompletionKind::Magic`.
+        if let Some(name) = find_node_at_offset::<ast::Name>(&file_with_fake_ident, offset) {
+            if let Some(bind_pat) = name.syntax().ancestors().find_map(ast::IdentPat::cast) {
+                self.is_pat_binding_or_const = true;
+                if bind_pat.at_token().is_some()
+                    || bind_pat.ref_token().is_some()
+                    || bind_pat.mut_token().is_some()
+                {
+                    self.is_pat_binding_or_const = false;
+                }
+                if bind_pat.syntax().parent().and_then(ast::RecordPatFieldList::cast).is_some() {
+                    self.is_pat_binding_or_const = false;
+                }
+                if let Some(let_stmt) = bind_pat.syntax().ancestors().find_map(ast::LetStmt::cast) {
+                    if let Some(pat) = let_stmt.pat() {
+                        if pat.syntax().text_range().contains_range(bind_pat.syntax().text_range())
+                        {
+                            self.is_pat_binding_or_const = false;
+                        }
+                    }
+                }
+            }
+            if is_node::<ast::Param>(name.syntax()) {
+                self.is_param = true;
+                return;
+            }
+            // FIXME: remove this (^) duplication and make the check more precise
+            if name.syntax().ancestors().find_map(ast::RecordPatFieldList::cast).is_some() {
+                self.record_pat_syntax =
+                    self.sema.find_node_at_offset_with_macros(&original_file, offset);
+            }
+        }
+    }
+
+    fn classify_name_ref(
+        &mut self,
+        original_file: &SyntaxNode,
+        name_ref: ast::NameRef,
+        offset: TextSize,
+    ) {
+        self.name_ref_syntax =
+            find_node_at_offset(&original_file, name_ref.syntax().text_range().start());
+        let name_range = name_ref.syntax().text_range();
+        if ast::RecordExprField::for_field_name(&name_ref).is_some() {
+            self.record_lit_syntax =
+                self.sema.find_node_at_offset_with_macros(&original_file, offset);
+        }
+
+        self.impl_def = self
+            .sema
+            .ancestors_with_macros(self.token.parent())
+            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
+            .find_map(ast::Impl::cast);
+
+        let top_node = name_ref
+            .syntax()
+            .ancestors()
+            .take_while(|it| it.text_range() == name_range)
+            .last()
+            .unwrap();
+
+        match top_node.parent().map(|it| it.kind()) {
+            Some(SOURCE_FILE) | Some(ITEM_LIST) => {
+                self.is_new_item = true;
+                return;
+            }
+            _ => (),
+        }
+
+        self.use_item_syntax =
+            self.sema.ancestors_with_macros(self.token.parent()).find_map(ast::Use::cast);
+
+        self.function_syntax = self
+            .sema
+            .ancestors_with_macros(self.token.parent())
+            .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
+            .find_map(ast::Fn::cast);
+
+        self.record_field_syntax = self
+            .sema
+            .ancestors_with_macros(self.token.parent())
+            .take_while(|it| {
+                it.kind() != SOURCE_FILE && it.kind() != MODULE && it.kind() != CALL_EXPR
+            })
+            .find_map(ast::RecordExprField::cast);
+
+        let parent = match name_ref.syntax().parent() {
+            Some(it) => it,
+            None => return,
+        };
+
+        if let Some(segment) = ast::PathSegment::cast(parent.clone()) {
+            let path = segment.parent_path();
+            self.is_call = path
+                .syntax()
+                .parent()
+                .and_then(ast::PathExpr::cast)
+                .and_then(|it| it.syntax().parent().and_then(ast::CallExpr::cast))
+                .is_some();
+            self.is_macro_call = path.syntax().parent().and_then(ast::MacroCall::cast).is_some();
+            self.is_pattern_call =
+                path.syntax().parent().and_then(ast::TupleStructPat::cast).is_some();
+
+            self.is_path_type = path.syntax().parent().and_then(ast::PathType::cast).is_some();
+            self.has_type_args = segment.generic_arg_list().is_some();
+
+            if let Some(path) = path_or_use_tree_qualifier(&path) {
+                self.path_qual = path
+                    .segment()
+                    .and_then(|it| {
+                        find_node_with_range::<ast::PathSegment>(
+                            original_file,
+                            it.syntax().text_range(),
+                        )
+                    })
+                    .map(|it| it.parent_path());
+                return;
+            }
+
+            if let Some(segment) = path.segment() {
+                if segment.coloncolon_token().is_some() {
+                    return;
+                }
+            }
+
+            self.is_trivial_path = true;
+
+            // Find either enclosing expr statement (thing with `;`) or a
+            // block. If block, check that we are the last expr.
+            self.can_be_stmt = name_ref
+                .syntax()
+                .ancestors()
+                .find_map(|node| {
+                    if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
+                        return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
+                    }
+                    if let Some(block) = ast::BlockExpr::cast(node) {
+                        return Some(
+                            block.expr().map(|e| e.syntax().text_range())
+                                == Some(name_ref.syntax().text_range()),
+                        );
+                    }
+                    None
+                })
+                .unwrap_or(false);
+            self.is_expr = path.syntax().parent().and_then(ast::PathExpr::cast).is_some();
+
+            if let Some(off) = name_ref.syntax().text_range().start().checked_sub(2.into()) {
+                if let Some(if_expr) =
+                    self.sema.find_node_at_offset_with_macros::<ast::IfExpr>(original_file, off)
+                {
+                    if if_expr.syntax().text_range().end() < name_ref.syntax().text_range().start()
+                    {
+                        self.after_if = true;
+                    }
+                }
+            }
+        }
+        if let Some(field_expr) = ast::FieldExpr::cast(parent.clone()) {
+            // The receiver comes before the point of insertion of the fake
+            // ident, so it should have the same range in the non-modified file
+            self.dot_receiver = field_expr
+                .expr()
+                .map(|e| e.syntax().text_range())
+                .and_then(|r| find_node_with_range(original_file, r));
+            self.dot_receiver_is_ambiguous_float_literal =
+                if let Some(ast::Expr::Literal(l)) = &self.dot_receiver {
+                    match l.kind() {
+                        ast::LiteralKind::FloatNumber { .. } => l.token().text().ends_with('.'),
+                        _ => false,
+                    }
+                } else {
+                    false
+                }
+        }
+        if let Some(method_call_expr) = ast::MethodCallExpr::cast(parent) {
+            // As above
+            self.dot_receiver = method_call_expr
+                .receiver()
+                .map(|e| e.syntax().text_range())
+                .and_then(|r| find_node_with_range(original_file, r));
+            self.is_call = true;
+        }
+    }
+}
+
+fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
+    find_covering_element(syntax, range).ancestors().find_map(N::cast)
+}
+
+fn is_node<N: AstNode>(node: &SyntaxNode) -> bool {
+    match node.ancestors().find_map(N::cast) {
+        None => false,
+        Some(n) => n.syntax().text_range() == node.text_range(),
+    }
+}
+
+fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<ast::Path> {
+    if let Some(qual) = path.qualifier() {
+        return Some(qual);
+    }
+    let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
+    let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
+    use_tree.path()
+}
diff --git a/crates/ide/src/completion/completion_item.rs b/crates/ide/src/completion/completion_item.rs
new file mode 100644
index 000000000..9377cdc57
--- /dev/null
+++ b/crates/ide/src/completion/completion_item.rs
@@ -0,0 +1,384 @@
+//! FIXME: write short doc here
+
+use std::fmt;
+
+use hir::Documentation;
+use syntax::TextRange;
+use text_edit::TextEdit;
+
+use crate::completion::completion_config::SnippetCap;
+
+/// `CompletionItem` describes a single completion variant in the editor pop-up.
+/// It is basically a POD with various properties. To construct a
+/// `CompletionItem`, use `new` method and the `Builder` struct.
+pub struct CompletionItem {
+    /// Used only internally in tests, to check only specific kind of
+    /// completion (postfix, keyword, reference, etc).
+    #[allow(unused)]
+    pub(crate) completion_kind: CompletionKind,
+    /// Label in the completion pop up which identifies completion.
+    label: String,
+    /// Range of identifier that is being completed.
+    ///
+    /// It should be used primarily for UI, but we also use this to convert
+    /// genetic TextEdit into LSP's completion edit (see conv.rs).
+    ///
+    /// `source_range` must contain the completion offset. `insert_text` should
+    /// start with what `source_range` points to, or VSCode will filter out the
+    /// completion silently.
+    source_range: TextRange,
+    /// What happens when user selects this item.
+    ///
+    /// Typically, replaces `source_range` with new identifier.
+    text_edit: TextEdit,
+    insert_text_format: InsertTextFormat,
+
+    /// What item (struct, function, etc) are we completing.
+    kind: Option<CompletionItemKind>,
+
+    /// Lookup is used to check if completion item indeed can complete current
+    /// ident.
+    ///
+    /// That is, in `foo.bar<|>` lookup of `abracadabra` will be accepted (it
+    /// contains `bar` sub sequence), and `quux` will rejected.
+    lookup: Option<String>,
+
+    /// Additional info to show in the UI pop up.
+    detail: Option<String>,
+    documentation: Option<Documentation>,
+
+    /// Whether this item is marked as deprecated
+    deprecated: bool,
+
+    /// If completing a function call, ask the editor to show parameter popup
+    /// after completion.
+    trigger_call_info: bool,
+
+    /// Score is useful to pre select or display in better order completion items
+    score: Option<CompletionScore>,
+}
+
+// We use custom debug for CompletionItem to make snapshot tests more readable.
+impl fmt::Debug for CompletionItem {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut s = f.debug_struct("CompletionItem");
+        s.field("label", &self.label()).field("source_range", &self.source_range());
+        if self.text_edit().len() == 1 {
+            let atom = &self.text_edit().iter().next().unwrap();
+            s.field("delete", &atom.delete);
+            s.field("insert", &atom.insert);
+        } else {
+            s.field("text_edit", &self.text_edit);
+        }
+        if let Some(kind) = self.kind().as_ref() {
+            s.field("kind", kind);
+        }
+        if self.lookup() != self.label() {
+            s.field("lookup", &self.lookup());
+        }
+        if let Some(detail) = self.detail() {
+            s.field("detail", &detail);
+        }
+        if let Some(documentation) = self.documentation() {
+            s.field("documentation", &documentation);
+        }
+        if self.deprecated {
+            s.field("deprecated", &true);
+        }
+        if let Some(score) = &self.score {
+            s.field("score", score);
+        }
+        if self.trigger_call_info {
+            s.field("trigger_call_info", &true);
+        }
+        s.finish()
+    }
+}
+
+#[derive(Debug, Clone, Copy, Ord, PartialOrd, Eq, PartialEq)]
+pub enum CompletionScore {
+    /// If only type match
+    TypeMatch,
+    /// If type and name match
+    TypeAndNameMatch,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CompletionItemKind {
+    Snippet,
+    Keyword,
+    Module,
+    Function,
+    BuiltinType,
+    Struct,
+    Enum,
+    EnumVariant,
+    Binding,
+    Field,
+    Static,
+    Const,
+    Trait,
+    TypeAlias,
+    Method,
+    TypeParam,
+    Macro,
+    Attribute,
+    UnresolvedReference,
+}
+
+impl CompletionItemKind {
+    #[cfg(test)]
+    pub(crate) fn tag(&self) -> &'static str {
+        match self {
+            CompletionItemKind::Attribute => "at",
+            CompletionItemKind::Binding => "bn",
+            CompletionItemKind::BuiltinType => "bt",
+            CompletionItemKind::Const => "ct",
+            CompletionItemKind::Enum => "en",
+            CompletionItemKind::EnumVariant => "ev",
+            CompletionItemKind::Field => "fd",
+            CompletionItemKind::Function => "fn",
+            CompletionItemKind::Keyword => "kw",
+            CompletionItemKind::Macro => "ma",
+            CompletionItemKind::Method => "me",
+            CompletionItemKind::Module => "md",
+            CompletionItemKind::Snippet => "sn",
+            CompletionItemKind::Static => "sc",
+            CompletionItemKind::Struct => "st",
+            CompletionItemKind::Trait => "tt",
+            CompletionItemKind::TypeAlias => "ta",
+            CompletionItemKind::TypeParam => "tp",
+            CompletionItemKind::UnresolvedReference => "??",
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+pub(crate) enum CompletionKind {
+    /// Parser-based keyword completion.
+    Keyword,
+    /// Your usual "complete all valid identifiers".
+    Reference,
+    /// "Secret sauce" completions.
+    Magic,
+    Snippet,
+    Postfix,
+    BuiltinType,
+    Attribute,
+}
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+pub enum InsertTextFormat {
+    PlainText,
+    Snippet,
+}
+
+impl CompletionItem {
+    pub(crate) fn new(
+        completion_kind: CompletionKind,
+        source_range: TextRange,
+        label: impl Into<String>,
+    ) -> Builder {
+        let label = label.into();
+        Builder {
+            source_range,
+            completion_kind,
+            label,
+            insert_text: None,
+            insert_text_format: InsertTextFormat::PlainText,
+            detail: None,
+            documentation: None,
+            lookup: None,
+            kind: None,
+            text_edit: None,
+            deprecated: None,
+            trigger_call_info: None,
+            score: None,
+        }
+    }
+    /// What user sees in pop-up in the UI.
+    pub fn label(&self) -> &str {
+        &self.label
+    }
+    pub fn source_range(&self) -> TextRange {
+        self.source_range
+    }
+
+    pub fn insert_text_format(&self) -> InsertTextFormat {
+        self.insert_text_format
+    }
+
+    pub fn text_edit(&self) -> &TextEdit {
+        &self.text_edit
+    }
+
+    /// Short one-line additional information, like a type
+    pub fn detail(&self) -> Option<&str> {
+        self.detail.as_deref()
+    }
+    /// A doc-comment
+    pub fn documentation(&self) -> Option<Documentation> {
+        self.documentation.clone()
+    }
+    /// What string is used for filtering.
+    pub fn lookup(&self) -> &str {
+        self.lookup.as_deref().unwrap_or(&self.label)
+    }
+
+    pub fn kind(&self) -> Option<CompletionItemKind> {
+        self.kind
+    }
+
+    pub fn deprecated(&self) -> bool {
+        self.deprecated
+    }
+
+    pub fn score(&self) -> Option<CompletionScore> {
+        self.score
+    }
+
+    pub fn trigger_call_info(&self) -> bool {
+        self.trigger_call_info
+    }
+}
+
+/// A helper to make `CompletionItem`s.
+#[must_use]
+pub(crate) struct Builder {
+    source_range: TextRange,
+    completion_kind: CompletionKind,
+    label: String,
+    insert_text: Option<String>,
+    insert_text_format: InsertTextFormat,
+    detail: Option<String>,
+    documentation: Option<Documentation>,
+    lookup: Option<String>,
+    kind: Option<CompletionItemKind>,
+    text_edit: Option<TextEdit>,
+    deprecated: Option<bool>,
+    trigger_call_info: Option<bool>,
+    score: Option<CompletionScore>,
+}
+
+impl Builder {
+    pub(crate) fn add_to(self, acc: &mut Completions) {
+        acc.add(self.build())
+    }
+
+    pub(crate) fn build(self) -> CompletionItem {
+        let label = self.label;
+        let text_edit = match self.text_edit {
+            Some(it) => it,
+            None => TextEdit::replace(
+                self.source_range,
+                self.insert_text.unwrap_or_else(|| label.clone()),
+            ),
+        };
+
+        CompletionItem {
+            source_range: self.source_range,
+            label,
+            insert_text_format: self.insert_text_format,
+            text_edit,
+            detail: self.detail,
+            documentation: self.documentation,
+            lookup: self.lookup,
+            kind: self.kind,
+            completion_kind: self.completion_kind,
+            deprecated: self.deprecated.unwrap_or(false),
+            trigger_call_info: self.trigger_call_info.unwrap_or(false),
+            score: self.score,
+        }
+    }
+    pub(crate) fn lookup_by(mut self, lookup: impl Into<String>) -> Builder {
+        self.lookup = Some(lookup.into());
+        self
+    }
+    pub(crate) fn label(mut self, label: impl Into<String>) -> Builder {
+        self.label = label.into();
+        self
+    }
+    pub(crate) fn insert_text(mut self, insert_text: impl Into<String>) -> Builder {
+        self.insert_text = Some(insert_text.into());
+        self
+    }
+    pub(crate) fn insert_snippet(
+        mut self,
+        _cap: SnippetCap,
+        snippet: impl Into<String>,
+    ) -> Builder {
+        self.insert_text_format = InsertTextFormat::Snippet;
+        self.insert_text(snippet)
+    }
+    pub(crate) fn kind(mut self, kind: CompletionItemKind) -> Builder {
+        self.kind = Some(kind);
+        self
+    }
+    pub(crate) fn text_edit(mut self, edit: TextEdit) -> Builder {
+        self.text_edit = Some(edit);
+        self
+    }
+    pub(crate) fn snippet_edit(mut self, _cap: SnippetCap, edit: TextEdit) -> Builder {
+        self.insert_text_format = InsertTextFormat::Snippet;
+        self.text_edit(edit)
+    }
+    #[allow(unused)]
+    pub(crate) fn detail(self, detail: impl Into<String>) -> Builder {
+        self.set_detail(Some(detail))
+    }
+    pub(crate) fn set_detail(mut self, detail: Option<impl Into<String>>) -> Builder {
+        self.detail = detail.map(Into::into);
+        self
+    }
+    #[allow(unused)]
+    pub(crate) fn documentation(self, docs: Documentation) -> Builder {
+        self.set_documentation(Some(docs))
+    }
+    pub(crate) fn set_documentation(mut self, docs: Option<Documentation>) -> Builder {
+        self.documentation = docs.map(Into::into);
+        self
+    }
+    pub(crate) fn set_deprecated(mut self, deprecated: bool) -> Builder {
+        self.deprecated = Some(deprecated);
+        self
+    }
+    pub(crate) fn set_score(mut self, score: CompletionScore) -> Builder {
+        self.score = Some(score);
+        self
+    }
+    pub(crate) fn trigger_call_info(mut self) -> Builder {
+        self.trigger_call_info = Some(true);
+        self
+    }
+}
+
+impl<'a> Into<CompletionItem> for Builder {
+    fn into(self) -> CompletionItem {
+        self.build()
+    }
+}
+
+/// Represents an in-progress set of completions being built.
+#[derive(Debug, Default)]
+pub(crate) struct Completions {
+    buf: Vec<CompletionItem>,
+}
+
+impl Completions {
+    pub(crate) fn add(&mut self, item: impl Into<CompletionItem>) {
+        self.buf.push(item.into())
+    }
+    pub(crate) fn add_all<I>(&mut self, items: I)
+    where
+        I: IntoIterator,
+        I::Item: Into<CompletionItem>,
+    {
+        items.into_iter().for_each(|item| self.add(item.into()))
+    }
+}
+
+impl Into<Vec<CompletionItem>> for Completions {
+    fn into(self) -> Vec<CompletionItem> {
+        self.buf
+    }
+}
diff --git a/crates/ide/src/completion/generated_features.rs b/crates/ide/src/completion/generated_features.rs
new file mode 100644
index 000000000..24754a8cf
--- /dev/null
+++ b/crates/ide/src/completion/generated_features.rs
@@ -0,0 +1,4 @@
+//! Generated file, do not edit by hand, see `xtask/src/codegen`
+
+use crate::completion::complete_attribute::LintCompletion;
+pub ( super ) const FEATURES : & [ LintCompletion ] = & [ LintCompletion { label : "doc_cfg" , description : "# `doc_cfg`\n\nThe tracking issue for this feature is: [#43781]\n\n------\n\nThe `doc_cfg` feature allows an API be documented as only available in some specific platforms.\nThis attribute has two effects:\n\n1. In the annotated item's documentation, there will be a message saying \"This is supported on\n    (platform) only\".\n\n2. The item's doc-tests will only run on the specific platform.\n\nIn addition to allowing the use of the `#[doc(cfg)]` attribute, this feature enables the use of a\nspecial conditional compilation flag, `#[cfg(doc)]`, set whenever building documentation on your\ncrate.\n\nThis feature was introduced as part of PR [#43348] to allow the platform-specific parts of the\nstandard library be documented.\n\n```rust\n#![feature(doc_cfg)]\n\n#[cfg(any(windows, doc))]\n#[doc(cfg(windows))]\n/// The application's icon in the notification area (a.k.a. system tray).\n///\n/// # Examples\n///\n/// ```no_run\n/// extern crate my_awesome_ui_library;\n/// use my_awesome_ui_library::current_app;\n/// use my_awesome_ui_library::windows::notification;\n///\n/// let icon = current_app().get::<notification::Icon>();\n/// icon.show();\n/// icon.show_message(\"Hello\");\n/// ```\npub struct Icon {\n    // ...\n}\n```\n\n[#43781]: https://github.com/rust-lang/rust/issues/43781\n[#43348]: https://github.com/rust-lang/rust/issues/43348\n" } , LintCompletion { label : "impl_trait_in_bindings" , description : "# `impl_trait_in_bindings`\n\nThe tracking issue for this feature is: [#63065]\n\n[#63065]: https://github.com/rust-lang/rust/issues/63065\n\n------------------------\n\nThe `impl_trait_in_bindings` feature gate lets you use `impl Trait` syntax in\n`let`, `static`, and `const` bindings.\n\nA simple example is:\n\n```rust\n#![feature(impl_trait_in_bindings)]\n\nuse std::fmt::Debug;\n\nfn main() {\n    let a: impl Debug + Clone = 42;\n    let b = a.clone();\n    println!(\"{:?}\", b); // prints `42`\n}\n```\n\nNote however that because the types of `a` and `b` are opaque in the above\nexample, calling inherent methods or methods outside of the specified traits\n(e.g., `a.abs()` or `b.abs()`) is not allowed, and yields an error.\n" } , LintCompletion { label : "plugin" , description : "# `plugin`\n\nThe tracking issue for this feature is: [#29597]\n\n[#29597]: https://github.com/rust-lang/rust/issues/29597\n\n\nThis feature is part of \"compiler plugins.\" It will often be used with the\n[`plugin_registrar`] and `rustc_private` features.\n\n[`plugin_registrar`]: plugin-registrar.md\n\n------------------------\n\n`rustc` can load compiler plugins, which are user-provided libraries that\nextend the compiler's behavior with new lint checks, etc.\n\nA plugin is a dynamic library crate with a designated *registrar* function that\nregisters extensions with `rustc`. Other crates can load these extensions using\nthe crate attribute `#![plugin(...)]`.  See the\n`rustc_driver::plugin` documentation for more about the\nmechanics of defining and loading a plugin.\n\nIn the vast majority of cases, a plugin should *only* be used through\n`#![plugin]` and not through an `extern crate` item.  Linking a plugin would\npull in all of librustc_ast and librustc as dependencies of your crate.  This is\ngenerally unwanted unless you are building another plugin.\n\nThe usual practice is to put compiler plugins in their own crate, separate from\nany `macro_rules!` macros or ordinary Rust code meant to be used by consumers\nof a library.\n\n# Lint plugins\n\nPlugins can extend [Rust's lint\ninfrastructure](../../reference/attributes/diagnostics.md#lint-check-attributes) with\nadditional checks for code style, safety, etc. Now let's write a plugin\n[`lint-plugin-test.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui-fulldeps/auxiliary/lint-plugin-test.rs)\nthat warns about any item named `lintme`.\n\n```rust,ignore\n#![feature(plugin_registrar)]\n#![feature(box_syntax, rustc_private)]\n\nextern crate rustc_ast;\n\n// Load rustc as a plugin to get macros\nextern crate rustc_driver;\n#[macro_use]\nextern crate rustc_lint;\n#[macro_use]\nextern crate rustc_session;\n\nuse rustc_driver::plugin::Registry;\nuse rustc_lint::{EarlyContext, EarlyLintPass, LintArray, LintContext, LintPass};\nuse rustc_ast::ast;\ndeclare_lint!(TEST_LINT, Warn, \"Warn about items named 'lintme'\");\n\ndeclare_lint_pass!(Pass => [TEST_LINT]);\n\nimpl EarlyLintPass for Pass {\n    fn check_item(&mut self, cx: &EarlyContext, it: &ast::Item) {\n        if it.ident.name.as_str() == \"lintme\" {\n            cx.lint(TEST_LINT, |lint| {\n                lint.build(\"item is named 'lintme'\").set_span(it.span).emit()\n            });\n        }\n    }\n}\n\n#[plugin_registrar]\npub fn plugin_registrar(reg: &mut Registry) {\n    reg.lint_store.register_lints(&[&TEST_LINT]);\n    reg.lint_store.register_early_pass(|| box Pass);\n}\n```\n\nThen code like\n\n```rust,ignore\n#![feature(plugin)]\n#![plugin(lint_plugin_test)]\n\nfn lintme() { }\n```\n\nwill produce a compiler warning:\n\n```txt\nfoo.rs:4:1: 4:16 warning: item is named 'lintme', #[warn(test_lint)] on by default\nfoo.rs:4 fn lintme() { }\n         ^~~~~~~~~~~~~~~\n```\n\nThe components of a lint plugin are:\n\n* one or more `declare_lint!` invocations, which define static `Lint` structs;\n\n* a struct holding any state needed by the lint pass (here, none);\n\n* a `LintPass`\n  implementation defining how to check each syntax element. A single\n  `LintPass` may call `span_lint` for several different `Lint`s, but should\n  register them all through the `get_lints` method.\n\nLint passes are syntax traversals, but they run at a late stage of compilation\nwhere type information is available. `rustc`'s [built-in\nlints](https://github.com/rust-lang/rust/blob/master/src/librustc_session/lint/builtin.rs)\nmostly use the same infrastructure as lint plugins, and provide examples of how\nto access type information.\n\nLints defined by plugins are controlled by the usual [attributes and compiler\nflags](../../reference/attributes/diagnostics.md#lint-check-attributes), e.g.\n`#[allow(test_lint)]` or `-A test-lint`. These identifiers are derived from the\nfirst argument to `declare_lint!`, with appropriate case and punctuation\nconversion.\n\nYou can run `rustc -W help foo.rs` to see a list of lints known to `rustc`,\nincluding those provided by plugins loaded by `foo.rs`.\n" } , LintCompletion { label : "infer_static_outlives_requirements" , description : "# `infer_static_outlives_requirements`\n\nThe tracking issue for this feature is: [#54185]\n\n[#54185]: https://github.com/rust-lang/rust/issues/54185\n\n------------------------\nThe `infer_static_outlives_requirements` feature indicates that certain\n`'static` outlives requirements can be inferred by the compiler rather than\nstating them explicitly.\n\nNote: It is an accompanying feature to `infer_outlives_requirements`,\nwhich must be enabled to infer outlives requirements.\n\nFor example, currently generic struct definitions that contain\nreferences, require where-clauses of the form T: 'static. By using\nthis feature the outlives predicates will be inferred, although\nthey may still be written explicitly.\n\n```rust,ignore (pseudo-Rust)\nstruct Foo<U> where U: 'static { // <-- currently required\n    bar: Bar<U>\n}\nstruct Bar<T: 'static> {\n    x: T,\n}\n```\n\n\n## Examples:\n\n```rust,ignore (pseudo-Rust)\n#![feature(infer_outlives_requirements)]\n#![feature(infer_static_outlives_requirements)]\n\n#[rustc_outlives]\n// Implicitly infer U: 'static\nstruct Foo<U> {\n    bar: Bar<U>\n}\nstruct Bar<T: 'static> {\n    x: T,\n}\n```\n\n" } , LintCompletion { label : "doc_alias" , description : "# `doc_alias`\n\nThe tracking issue for this feature is: [#50146]\n\n[#50146]: https://github.com/rust-lang/rust/issues/50146\n\n------------------------\n\nYou can add alias(es) to an item when using the `rustdoc` search through the\n`doc(alias)` attribute. Example:\n\n```rust,no_run\n#![feature(doc_alias)]\n\n#[doc(alias = \"x\")]\n#[doc(alias = \"big\")]\npub struct BigX;\n```\n\nThen, when looking for it through the `rustdoc` search, if you enter \"x\" or\n\"big\", search will show the `BigX` struct first.\n\nNote that this feature is currently hidden behind the `feature(doc_alias)` gate.\n" } , LintCompletion { label : "optin_builtin_traits" , description : "# `optin_builtin_traits`\n\nThe tracking issue for this feature is [#13231] \n\n[#13231]: https://github.com/rust-lang/rust/issues/13231\n\n----\n\nThe `optin_builtin_traits` feature gate allows you to define auto traits.\n\nAuto traits, like [`Send`] or [`Sync`] in the standard library, are marker traits\nthat are automatically implemented for every type, unless the type, or a type it contains, \nhas explicitly opted out via a negative impl. (Negative impls are separately controlled\nby the `negative_impls` feature.)\n\n[`Send`]: https://doc.rust-lang.org/std/marker/trait.Send.html\n[`Sync`]: https://doc.rust-lang.org/std/marker/trait.Sync.html\n\n```rust,ignore\nimpl !Trait for Type\n```\n\nExample:\n\n```rust\n#![feature(negative_impls)]\n#![feature(optin_builtin_traits)]\n\nauto trait Valid {}\n\nstruct True;\nstruct False;\n\nimpl !Valid for False {}\n\nstruct MaybeValid<T>(T);\n\nfn must_be_valid<T: Valid>(_t: T) { }\n\nfn main() {\n    // works\n    must_be_valid( MaybeValid(True) );\n                \n    // compiler error - trait bound not satisfied\n    // must_be_valid( MaybeValid(False) );\n}\n```\n\n## Automatic trait implementations\n\nWhen a type is declared as an `auto trait`, we will automatically\ncreate impls for every struct/enum/union, unless an explicit impl is\nprovided. These automatic impls contain a where clause for each field\nof the form `T: AutoTrait`, where `T` is the type of the field and\n`AutoTrait` is the auto trait in question. As an example, consider the\nstruct `List` and the auto trait `Send`:\n\n```rust\nstruct List<T> {\n  data: T,\n  next: Option<Box<List<T>>>,\n}\n```\n\nPresuming that there is no explicit impl of `Send` for `List`, the\ncompiler will supply an automatic impl of the form:\n\n```rust\nstruct List<T> {\n  data: T,\n  next: Option<Box<List<T>>>,\n}\n\nunsafe impl<T> Send for List<T>\nwhere\n  T: Send, // from the field `data`\n  Option<Box<List<T>>>: Send, // from the field `next`\n{ }\n```\n\nExplicit impls may be either positive or negative. They take the form:\n\n```rust,ignore\nimpl<...> AutoTrait for StructName<..> { }\nimpl<...> !AutoTrait for StructName<..> { }\n```\n\n## Coinduction: Auto traits permit cyclic matching\n\nUnlike ordinary trait matching, auto traits are **coinductive**. This\nmeans, in short, that cycles which occur in trait matching are\nconsidered ok. As an example, consider the recursive struct `List`\nintroduced in the previous section. In attempting to determine whether\n`List: Send`, we would wind up in a cycle: to apply the impl, we must\nshow that `Option<Box<List>>: Send`, which will in turn require\n`Box<List>: Send` and then finally `List: Send` again. Under ordinary\ntrait matching, this cycle would be an error, but for an auto trait it\nis considered a successful match.\n\n## Items\n\nAuto traits cannot have any trait items, such as methods or associated types. This ensures that we can generate default implementations.\n\n## Supertraits\n\nAuto traits cannot have supertraits. This is for soundness reasons, as the interaction of coinduction with implied bounds is difficult to reconcile.\n\n" } , LintCompletion { label : "const_in_array_repeat_expressions" , description : "# `const_in_array_repeat_expressions`\n\nThe tracking issue for this feature is: [#49147]\n\n[#49147]: https://github.com/rust-lang/rust/issues/49147\n\n------------------------\n\nRelaxes the rules for repeat expressions, `[x; N]` such that `x` may also be `const` (strictly\nspeaking rvalue promotable), in addition to `typeof(x): Copy`. The result of `[x; N]` where `x` is\n`const` is itself also `const`.\n" } , LintCompletion { label : "generators" , description : "# `generators`\n\nThe tracking issue for this feature is: [#43122]\n\n[#43122]: https://github.com/rust-lang/rust/issues/43122\n\n------------------------\n\nThe `generators` feature gate in Rust allows you to define generator or\ncoroutine literals. A generator is a \"resumable function\" that syntactically\nresembles a closure but compiles to much different semantics in the compiler\nitself. The primary feature of a generator is that it can be suspended during\nexecution to be resumed at a later date. Generators use the `yield` keyword to\n\"return\", and then the caller can `resume` a generator to resume execution just\nafter the `yield` keyword.\n\nGenerators are an extra-unstable feature in the compiler right now. Added in\n[RFC 2033] they're mostly intended right now as a information/constraint\ngathering phase. The intent is that experimentation can happen on the nightly\ncompiler before actual stabilization. A further RFC will be required to\nstabilize generators/coroutines and will likely contain at least a few small\ntweaks to the overall design.\n\n[RFC 2033]: https://github.com/rust-lang/rfcs/pull/2033\n\nA syntactical example of a generator is:\n\n```rust\n#![feature(generators, generator_trait)]\n\nuse std::ops::{Generator, GeneratorState};\nuse std::pin::Pin;\n\nfn main() {\n    let mut generator = || {\n        yield 1;\n        return \"foo\"\n    };\n\n    match Pin::new(&mut generator).resume(()) {\n        GeneratorState::Yielded(1) => {}\n        _ => panic!(\"unexpected value from resume\"),\n    }\n    match Pin::new(&mut generator).resume(()) {\n        GeneratorState::Complete(\"foo\") => {}\n        _ => panic!(\"unexpected value from resume\"),\n    }\n}\n```\n\nGenerators are closure-like literals which can contain a `yield` statement. The\n`yield` statement takes an optional expression of a value to yield out of the\ngenerator. All generator literals implement the `Generator` trait in the\n`std::ops` module. The `Generator` trait has one main method, `resume`, which\nresumes execution of the generator at the previous suspension point.\n\nAn example of the control flow of generators is that the following example\nprints all numbers in order:\n\n```rust\n#![feature(generators, generator_trait)]\n\nuse std::ops::Generator;\nuse std::pin::Pin;\n\nfn main() {\n    let mut generator = || {\n        println!(\"2\");\n        yield;\n        println!(\"4\");\n    };\n\n    println!(\"1\");\n    Pin::new(&mut generator).resume(());\n    println!(\"3\");\n    Pin::new(&mut generator).resume(());\n    println!(\"5\");\n}\n```\n\nAt this time the main intended use case of generators is an implementation\nprimitive for async/await syntax, but generators will likely be extended to\nergonomic implementations of iterators and other primitives in the future.\nFeedback on the design and usage is always appreciated!\n\n### The `Generator` trait\n\nThe `Generator` trait in `std::ops` currently looks like:\n\n```rust\n# #![feature(arbitrary_self_types, generator_trait)]\n# use std::ops::GeneratorState;\n# use std::pin::Pin;\n\npub trait Generator<R = ()> {\n    type Yield;\n    type Return;\n    fn resume(self: Pin<&mut Self>, resume: R) -> GeneratorState<Self::Yield, Self::Return>;\n}\n```\n\nThe `Generator::Yield` type is the type of values that can be yielded with the\n`yield` statement. The `Generator::Return` type is the returned type of the\ngenerator. This is typically the last expression in a generator's definition or\nany value passed to `return` in a generator. The `resume` function is the entry\npoint for executing the `Generator` itself.\n\nThe return value of `resume`, `GeneratorState`, looks like:\n\n```rust\npub enum GeneratorState<Y, R> {\n    Yielded(Y),\n    Complete(R),\n}\n```\n\nThe `Yielded` variant indicates that the generator can later be resumed. This\ncorresponds to a `yield` point in a generator. The `Complete` variant indicates\nthat the generator is complete and cannot be resumed again. Calling `resume`\nafter a generator has returned `Complete` will likely result in a panic of the\nprogram.\n\n### Closure-like semantics\n\nThe closure-like syntax for generators alludes to the fact that they also have\nclosure-like semantics. Namely:\n\n* When created, a generator executes no code. A closure literal does not\n  actually execute any of the closure's code on construction, and similarly a\n  generator literal does not execute any code inside the generator when\n  constructed.\n\n* Generators can capture outer variables by reference or by move, and this can\n  be tweaked with the `move` keyword at the beginning of the closure. Like\n  closures all generators will have an implicit environment which is inferred by\n  the compiler. Outer variables can be moved into a generator for use as the\n  generator progresses.\n\n* Generator literals produce a value with a unique type which implements the\n  `std::ops::Generator` trait. This allows actual execution of the generator\n  through the `Generator::resume` method as well as also naming it in return\n  types and such.\n\n* Traits like `Send` and `Sync` are automatically implemented for a `Generator`\n  depending on the captured variables of the environment. Unlike closures,\n  generators also depend on variables live across suspension points. This means\n  that although the ambient environment may be `Send` or `Sync`, the generator\n  itself may not be due to internal variables live across `yield` points being\n  not-`Send` or not-`Sync`. Note that generators do\n  not implement traits like `Copy` or `Clone` automatically.\n\n* Whenever a generator is dropped it will drop all captured environment\n  variables.\n\n### Generators as state machines\n\nIn the compiler, generators are currently compiled as state machines. Each\n`yield` expression will correspond to a different state that stores all live\nvariables over that suspension point. Resumption of a generator will dispatch on\nthe current state and then execute internally until a `yield` is reached, at\nwhich point all state is saved off in the generator and a value is returned.\n\nLet's take a look at an example to see what's going on here:\n\n```rust\n#![feature(generators, generator_trait)]\n\nuse std::ops::Generator;\nuse std::pin::Pin;\n\nfn main() {\n    let ret = \"foo\";\n    let mut generator = move || {\n        yield 1;\n        return ret\n    };\n\n    Pin::new(&mut generator).resume(());\n    Pin::new(&mut generator).resume(());\n}\n```\n\nThis generator literal will compile down to something similar to:\n\n```rust\n#![feature(arbitrary_self_types, generators, generator_trait)]\n\nuse std::ops::{Generator, GeneratorState};\nuse std::pin::Pin;\n\nfn main() {\n    let ret = \"foo\";\n    let mut generator = {\n        enum __Generator {\n            Start(&'static str),\n            Yield1(&'static str),\n            Done,\n        }\n\n        impl Generator for __Generator {\n            type Yield = i32;\n            type Return = &'static str;\n\n            fn resume(mut self: Pin<&mut Self>, resume: ()) -> GeneratorState<i32, &'static str> {\n                use std::mem;\n                match mem::replace(&mut *self, __Generator::Done) {\n                    __Generator::Start(s) => {\n                        *self = __Generator::Yield1(s);\n                        GeneratorState::Yielded(1)\n                    }\n\n                    __Generator::Yield1(s) => {\n                        *self = __Generator::Done;\n                        GeneratorState::Complete(s)\n                    }\n\n                    __Generator::Done => {\n                        panic!(\"generator resumed after completion\")\n                    }\n                }\n            }\n        }\n\n        __Generator::Start(ret)\n    };\n\n    Pin::new(&mut generator).resume(());\n    Pin::new(&mut generator).resume(());\n}\n```\n\nNotably here we can see that the compiler is generating a fresh type,\n`__Generator` in this case. This type has a number of states (represented here\nas an `enum`) corresponding to each of the conceptual states of the generator.\nAt the beginning we're closing over our outer variable `foo` and then that\nvariable is also live over the `yield` point, so it's stored in both states.\n\nWhen the generator starts it'll immediately yield 1, but it saves off its state\njust before it does so indicating that it has reached the yield point. Upon\nresuming again we'll execute the `return ret` which returns the `Complete`\nstate.\n\nHere we can also note that the `Done` state, if resumed, panics immediately as\nit's invalid to resume a completed generator. It's also worth noting that this\nis just a rough desugaring, not a normative specification for what the compiler\ndoes.\n" } , LintCompletion { label : "unsized_tuple_coercion" , description : "# `unsized_tuple_coercion`\n\nThe tracking issue for this feature is: [#42877]\n\n[#42877]: https://github.com/rust-lang/rust/issues/42877\n\n------------------------\n\nThis is a part of [RFC0401]. According to the RFC, there should be an implementation like this:\n\n```rust,ignore\nimpl<..., T, U: ?Sized> Unsized<(..., U)> for (..., T) where T: Unsized<U> {}\n```\n\nThis implementation is currently gated behind `#[feature(unsized_tuple_coercion)]` to avoid insta-stability. Therefore you can use it like this:\n\n```rust\n#![feature(unsized_tuple_coercion)]\n\nfn main() {\n    let x : ([i32; 3], [i32; 3]) = ([1, 2, 3], [4, 5, 6]);\n    let y : &([i32; 3], [i32]) = &x;\n    assert_eq!(y.1[0], 4);\n}\n```\n\n[RFC0401]: https://github.com/rust-lang/rfcs/blob/master/text/0401-coercions.md\n" } , LintCompletion { label : "cfg_version" , description : "# `cfg_version`\n\nThe tracking issue for this feature is: [#64796]\n\n[#64796]: https://github.com/rust-lang/rust/issues/64796\n\n------------------------\n\nThe `cfg_version` feature makes it possible to execute different code\ndepending on the compiler version.\n\n## Examples\n\n```rust\n#![feature(cfg_version)]\n\n#[cfg(version(\"1.42\"))]\nfn a() {\n    // ...\n}\n\n#[cfg(not(version(\"1.42\")))]\nfn a() {\n    // ...\n}\n\nfn b() {\n    if cfg!(version(\"1.42\")) {\n        // ...\n    } else {\n        // ...\n    }\n}\n```\n" } , LintCompletion { label : "ffi_const" , description : "# `ffi_const`\n\nThe `#[ffi_const]` attribute applies clang's `const` attribute to foreign\nfunctions declarations.\n\nThat is, `#[ffi_const]` functions shall have no effects except for its return\nvalue, which can only depend on the values of the function parameters, and is\nnot affected by changes to the observable state of the program.\n\nApplying the `#[ffi_const]` attribute to a function that violates these\nrequirements is undefined behaviour.\n\nThis attribute enables Rust to perform common optimizations, like sub-expression\nelimination, and it can avoid emitting some calls in repeated invocations of the\nfunction with the same argument values regardless of other operations being\nperformed in between these functions calls (as opposed to `#[ffi_pure]`\nfunctions).\n\n## Pitfalls\n\nA `#[ffi_const]` function can only read global memory that would not affect\nits return value for the whole execution of the program (e.g. immutable global\nmemory). `#[ffi_const]` functions are referentially-transparent and therefore\nmore strict than `#[ffi_pure]` functions.\n\nA common pitfall involves applying the `#[ffi_const]` attribute to a\nfunction that reads memory through pointer arguments which do not necessarily\npoint to immutable global memory.\n\nA `#[ffi_const]` function that returns unit has no effect on the abstract\nmachine's state, and a `#[ffi_const]` function cannot be `#[ffi_pure]`.\n\nA `#[ffi_const]` function must not diverge, neither via a side effect (e.g. a\ncall to `abort`) nor by infinite loops.\n\nWhen translating C headers to Rust FFI, it is worth verifying for which targets\nthe `const` attribute is enabled in those headers, and using the appropriate\n`cfg` macros in the Rust side to match those definitions. While the semantics of\n`const` are implemented identically by many C and C++ compilers, e.g., clang,\n[GCC], [ARM C/C++ compiler], [IBM ILE C/C++], etc. they are not necessarily\nimplemented in this way on all of them. It is therefore also worth verifying\nthat the semantics of the C toolchain used to compile the binary being linked\nagainst are compatible with those of the `#[ffi_const]`.\n\n[ARM C/C++ compiler]: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0491c/Cacgigch.html\n[GCC]: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute\n[IBM ILE C/C++]: https://www.ibm.com/support/knowledgecenter/fr/ssw_ibm_i_71/rzarg/fn_attrib_const.htm\n" } , LintCompletion { label : "const_fn" , description : "# `const_fn`\n\nThe tracking issue for this feature is: [#57563]\n\n[#57563]: https://github.com/rust-lang/rust/issues/57563\n\n------------------------\n\nThe `const_fn` feature allows marking free functions and inherent methods as\n`const`, enabling them to be called in constants contexts, with constant\narguments.\n\n## Examples\n\n```rust\n#![feature(const_fn)]\n\nconst fn double(x: i32) -> i32 {\n    x * 2\n}\n\nconst FIVE: i32 = 5;\nconst TEN: i32 = double(FIVE);\n\nfn main() {\n    assert_eq!(5, FIVE);\n    assert_eq!(10, TEN);\n}\n```\n" } , LintCompletion { label : "unsized_locals" , description : "# `unsized_locals`\n\nThe tracking issue for this feature is: [#48055]\n\n[#48055]: https://github.com/rust-lang/rust/issues/48055\n\n------------------------\n\nThis implements [RFC1909]. When turned on, you can have unsized arguments and locals:\n\n[RFC1909]: https://github.com/rust-lang/rfcs/blob/master/text/1909-unsized-rvalues.md\n\n```rust\n#![feature(unsized_locals)]\n\nuse std::any::Any;\n\nfn main() {\n    let x: Box<dyn Any> = Box::new(42);\n    let x: dyn Any = *x;\n    //  ^ unsized local variable\n    //               ^^ unsized temporary\n    foo(x);\n}\n\nfn foo(_: dyn Any) {}\n//     ^^^^^^ unsized argument\n```\n\nThe RFC still forbids the following unsized expressions:\n\n```rust,ignore\n#![feature(unsized_locals)]\n\nuse std::any::Any;\n\nstruct MyStruct<T: ?Sized> {\n    content: T,\n}\n\nstruct MyTupleStruct<T: ?Sized>(T);\n\nfn answer() -> Box<dyn Any> {\n    Box::new(42)\n}\n\nfn main() {\n    // You CANNOT have unsized statics.\n    static X: dyn Any = *answer();  // ERROR\n    const Y: dyn Any = *answer();  // ERROR\n\n    // You CANNOT have struct initialized unsized.\n    MyStruct { content: *answer() };  // ERROR\n    MyTupleStruct(*answer());  // ERROR\n    (42, *answer());  // ERROR\n\n    // You CANNOT have unsized return types.\n    fn my_function() -> dyn Any { *answer() }  // ERROR\n\n    // You CAN have unsized local variables...\n    let mut x: dyn Any = *answer();  // OK\n    // ...but you CANNOT reassign to them.\n    x = *answer();  // ERROR\n\n    // You CANNOT even initialize them separately.\n    let y: dyn Any;  // OK\n    y = *answer();  // ERROR\n\n    // Not mentioned in the RFC, but by-move captured variables are also Sized.\n    let x: dyn Any = *answer();\n    (move || {  // ERROR\n        let y = x;\n    })();\n\n    // You CAN create a closure with unsized arguments,\n    // but you CANNOT call it.\n    // This is an implementation detail and may be changed in the future.\n    let f = |x: dyn Any| {};\n    f(*answer());  // ERROR\n}\n```\n\n## By-value trait objects\n\nWith this feature, you can have by-value `self` arguments without `Self: Sized` bounds.\n\n```rust\n#![feature(unsized_locals)]\n\ntrait Foo {\n    fn foo(self) {}\n}\n\nimpl<T: ?Sized> Foo for T {}\n\nfn main() {\n    let slice: Box<[i32]> = Box::new([1, 2, 3]);\n    <[i32] as Foo>::foo(*slice);\n}\n```\n\nAnd `Foo` will also be object-safe.\n\n```rust\n#![feature(unsized_locals)]\n\ntrait Foo {\n    fn foo(self) {}\n}\n\nimpl<T: ?Sized> Foo for T {}\n\nfn main () {\n    let slice: Box<dyn Foo> = Box::new([1, 2, 3]);\n    // doesn't compile yet\n    <dyn Foo as Foo>::foo(*slice);\n}\n```\n\nOne of the objectives of this feature is to allow `Box<dyn FnOnce>`.\n\n## Variable length arrays\n\nThe RFC also describes an extension to the array literal syntax: `[e; dyn n]`. In the syntax, `n` isn't necessarily a constant expression. The array is dynamically allocated on the stack and has the type of `[T]`, instead of `[T; n]`.\n\n```rust,ignore\n#![feature(unsized_locals)]\n\nfn mergesort<T: Ord>(a: &mut [T]) {\n    let mut tmp = [T; dyn a.len()];\n    // ...\n}\n\nfn main() {\n    let mut a = [3, 1, 5, 6];\n    mergesort(&mut a);\n    assert_eq!(a, [1, 3, 5, 6]);\n}\n```\n\nVLAs are not implemented yet. The syntax isn't final, either. We may need an alternative syntax for Rust 2015 because, in Rust 2015, expressions like `[e; dyn(1)]` would be ambiguous. One possible alternative proposed in the RFC is `[e; n]`: if `n` captures one or more local variables, then it is considered as `[e; dyn n]`.\n\n## Advisory on stack usage\n\nIt's advised not to casually use the `#![feature(unsized_locals)]` feature. Typical use-cases are:\n\n- When you need a by-value trait objects.\n- When you really need a fast allocation of small temporary arrays.\n\nAnother pitfall is repetitive allocation and temporaries. Currently the compiler simply extends the stack frame every time it encounters an unsized assignment. So for example, the code\n\n```rust\n#![feature(unsized_locals)]\n\nfn main() {\n    let x: Box<[i32]> = Box::new([1, 2, 3, 4, 5]);\n    let _x = {{{{{{{{{{*x}}}}}}}}}};\n}\n```\n\nand the code\n\n```rust\n#![feature(unsized_locals)]\n\nfn main() {\n    for _ in 0..10 {\n        let x: Box<[i32]> = Box::new([1, 2, 3, 4, 5]);\n        let _x = *x;\n    }\n}\n```\n\nwill unnecessarily extend the stack frame.\n" } , LintCompletion { label : "or_patterns" , description : "# `or_patterns`\n\nThe tracking issue for this feature is: [#54883]\n\n[#54883]: https://github.com/rust-lang/rust/issues/54883\n\n------------------------\n\nThe `or_pattern` language feature allows `|` to be arbitrarily nested within\na pattern, for example, `Some(A(0) | B(1 | 2))` becomes a valid pattern.\n\n## Examples\n\n```rust,ignore\n#![feature(or_patterns)]\n\npub enum Foo {\n    Bar,\n    Baz,\n    Quux,\n}\n\npub fn example(maybe_foo: Option<Foo>) {\n    match maybe_foo {\n        Some(Foo::Bar | Foo::Baz) => {\n            println!(\"The value contained `Bar` or `Baz`\");\n        }\n        Some(_) => {\n            println!(\"The value did not contain `Bar` or `Baz`\");\n        }\n        None => {\n            println!(\"The value was `None`\");\n        }\n    }\n}\n```\n" } , LintCompletion { label : "no_sanitize" , description : "# `no_sanitize`\n\nThe tracking issue for this feature is: [#39699]\n\n[#39699]: https://github.com/rust-lang/rust/issues/39699\n\n------------------------\n\nThe `no_sanitize` attribute can be used to selectively disable sanitizer\ninstrumentation in an annotated function. This might be useful to: avoid\ninstrumentation overhead in a performance critical function, or avoid\ninstrumenting code that contains constructs unsupported by given sanitizer.\n\nThe precise effect of this annotation depends on particular sanitizer in use.\nFor example, with `no_sanitize(thread)`, the thread sanitizer will no longer\ninstrument non-atomic store / load operations, but it will instrument atomic\noperations to avoid reporting false positives and provide meaning full stack\ntraces.\n\n## Examples\n\n``` rust\n#![feature(no_sanitize)]\n\n#[no_sanitize(address)]\nfn foo() {\n  // ...\n}\n```\n" } , LintCompletion { label : "doc_spotlight" , description : "# `doc_spotlight`\n\nThe tracking issue for this feature is: [#45040]\n\nThe `doc_spotlight` feature allows the use of the `spotlight` parameter to the `#[doc]` attribute,\nto \"spotlight\" a specific trait on the return values of functions. Adding a `#[doc(spotlight)]`\nattribute to a trait definition will make rustdoc print extra information for functions which return\na type that implements that trait. This attribute is applied to the `Iterator`, `io::Read`, and\n`io::Write` traits in the standard library.\n\nYou can do this on your own traits, like this:\n\n```\n#![feature(doc_spotlight)]\n\n#[doc(spotlight)]\npub trait MyTrait {}\n\npub struct MyStruct;\nimpl MyTrait for MyStruct {}\n\n/// The docs for this function will have an extra line about `MyStruct` implementing `MyTrait`,\n/// without having to write that yourself!\npub fn my_fn() -> MyStruct { MyStruct }\n```\n\nThis feature was originally implemented in PR [#45039].\n\n[#45040]: https://github.com/rust-lang/rust/issues/45040\n[#45039]: https://github.com/rust-lang/rust/pull/45039\n" } , LintCompletion { label : "cfg_sanitize" , description : "# `cfg_sanitize`\n\nThe tracking issue for this feature is: [#39699]\n\n[#39699]: https://github.com/rust-lang/rust/issues/39699\n\n------------------------\n\nThe `cfg_sanitize` feature makes it possible to execute different code\ndepending on whether a particular sanitizer is enabled or not.\n\n## Examples\n\n```rust\n#![feature(cfg_sanitize)]\n\n#[cfg(sanitize = \"thread\")]\nfn a() {\n    // ...\n}\n\n#[cfg(not(sanitize = \"thread\"))]\nfn a() {\n    // ...\n}\n\nfn b() {\n    if cfg!(sanitize = \"leak\") {\n        // ...\n    } else {\n        // ...\n    }\n}\n```\n" } , LintCompletion { label : "doc_masked" , description : "# `doc_masked`\n\nThe tracking issue for this feature is: [#44027]\n\n-----\n\nThe `doc_masked` feature allows a crate to exclude types from a given crate from appearing in lists\nof trait implementations. The specifics of the feature are as follows:\n\n1. When rustdoc encounters an `extern crate` statement annotated with a `#[doc(masked)]` attribute,\n   it marks the crate as being masked.\n\n2. When listing traits a given type implements, rustdoc ensures that traits from masked crates are\n   not emitted into the documentation.\n\n3. When listing types that implement a given trait, rustdoc ensures that types from masked crates\n   are not emitted into the documentation.\n\nThis feature was introduced in PR [#44026] to ensure that compiler-internal and\nimplementation-specific types and traits were not included in the standard library's documentation.\nSuch types would introduce broken links into the documentation.\n\n[#44026]: https://github.com/rust-lang/rust/pull/44026\n[#44027]: https://github.com/rust-lang/rust/pull/44027\n" } , LintCompletion { label : "abi_thiscall" , description : "# `abi_thiscall`\n\nThe tracking issue for this feature is: [#42202]\n\n[#42202]: https://github.com/rust-lang/rust/issues/42202\n\n------------------------\n\nThe MSVC ABI on x86 Windows uses the `thiscall` calling convention for C++\ninstance methods by default; it is identical to the usual (C) calling\nconvention on x86 Windows except that the first parameter of the method,\nthe `this` pointer, is passed in the ECX register.\n" } , LintCompletion { label : "lang_items" , description : "# `lang_items`\n\nThe tracking issue for this feature is: None.\n\n------------------------\n\nThe `rustc` compiler has certain pluggable operations, that is,\nfunctionality that isn't hard-coded into the language, but is\nimplemented in libraries, with a special marker to tell the compiler\nit exists. The marker is the attribute `#[lang = \"...\"]` and there are\nvarious different values of `...`, i.e. various different 'lang\nitems'.\n\nFor example, `Box` pointers require two lang items, one for allocation\nand one for deallocation. A freestanding program that uses the `Box`\nsugar for dynamic allocations via `malloc` and `free`:\n\n```rust,ignore\n#![feature(lang_items, box_syntax, start, libc, core_intrinsics)]\n#![no_std]\nuse core::intrinsics;\nuse core::panic::PanicInfo;\n\nextern crate libc;\n\n#[lang = \"owned_box\"]\npub struct Box<T>(*mut T);\n\n#[lang = \"exchange_malloc\"]\nunsafe fn allocate(size: usize, _align: usize) -> *mut u8 {\n    let p = libc::malloc(size as libc::size_t) as *mut u8;\n\n    // Check if `malloc` failed:\n    if p as usize == 0 {\n        intrinsics::abort();\n    }\n\n    p\n}\n\n#[lang = \"box_free\"]\nunsafe fn box_free<T: ?Sized>(ptr: *mut T) {\n    libc::free(ptr as *mut libc::c_void)\n}\n\n#[start]\nfn main(_argc: isize, _argv: *const *const u8) -> isize {\n    let _x = box 1;\n\n    0\n}\n\n#[lang = \"eh_personality\"] extern fn rust_eh_personality() {}\n#[lang = \"panic_impl\"] extern fn rust_begin_panic(info: &PanicInfo) -> ! { unsafe { intrinsics::abort() } }\n#[no_mangle] pub extern fn rust_eh_register_frames () {}\n#[no_mangle] pub extern fn rust_eh_unregister_frames () {}\n```\n\nNote the use of `abort`: the `exchange_malloc` lang item is assumed to\nreturn a valid pointer, and so needs to do the check internally.\n\nOther features provided by lang items include:\n\n- overloadable operators via traits: the traits corresponding to the\n  `==`, `<`, dereferencing (`*`) and `+` (etc.) operators are all\n  marked with lang items; those specific four are `eq`, `ord`,\n  `deref`, and `add` respectively.\n- stack unwinding and general failure; the `eh_personality`,\n  `panic` and `panic_bounds_checks` lang items.\n- the traits in `std::marker` used to indicate types of\n  various kinds; lang items `send`, `sync` and `copy`.\n- the marker types and variance indicators found in\n  `std::marker`; lang items `covariant_type`,\n  `contravariant_lifetime`, etc.\n\nLang items are loaded lazily by the compiler; e.g. if one never uses\n`Box` then there is no need to define functions for `exchange_malloc`\nand `box_free`. `rustc` will emit an error when an item is needed\nbut not found in the current crate or any that it depends on.\n\nMost lang items are defined by `libcore`, but if you're trying to build\nan executable without the standard library, you'll run into the need\nfor lang items. The rest of this page focuses on this use-case, even though\nlang items are a bit broader than that.\n\n### Using libc\n\nIn order to build a `#[no_std]` executable we will need libc as a dependency.\nWe can specify this using our `Cargo.toml` file:\n\n```toml\n[dependencies]\nlibc = { version = \"0.2.14\", default-features = false }\n```\n\nNote that the default features have been disabled. This is a critical step -\n**the default features of libc include the standard library and so must be\ndisabled.**\n\n### Writing an executable without stdlib\n\nControlling the entry point is possible in two ways: the `#[start]` attribute,\nor overriding the default shim for the C `main` function with your own.\n\nThe function marked `#[start]` is passed the command line parameters\nin the same format as C:\n\n```rust,ignore\n#![feature(lang_items, core_intrinsics)]\n#![feature(start)]\n#![no_std]\nuse core::intrinsics;\nuse core::panic::PanicInfo;\n\n// Pull in the system libc library for what crt0.o likely requires.\nextern crate libc;\n\n// Entry point for this program.\n#[start]\nfn start(_argc: isize, _argv: *const *const u8) -> isize {\n    0\n}\n\n// These functions are used by the compiler, but not\n// for a bare-bones hello world. These are normally\n// provided by libstd.\n#[lang = \"eh_personality\"]\n#[no_mangle]\npub extern fn rust_eh_personality() {\n}\n\n#[lang = \"panic_impl\"]\n#[no_mangle]\npub extern fn rust_begin_panic(info: &PanicInfo) -> ! {\n    unsafe { intrinsics::abort() }\n}\n```\n\nTo override the compiler-inserted `main` shim, one has to disable it\nwith `#![no_main]` and then create the appropriate symbol with the\ncorrect ABI and the correct name, which requires overriding the\ncompiler's name mangling too:\n\n```rust,ignore\n#![feature(lang_items, core_intrinsics)]\n#![feature(start)]\n#![no_std]\n#![no_main]\nuse core::intrinsics;\nuse core::panic::PanicInfo;\n\n// Pull in the system libc library for what crt0.o likely requires.\nextern crate libc;\n\n// Entry point for this program.\n#[no_mangle] // ensure that this symbol is called `main` in the output\npub extern fn main(_argc: i32, _argv: *const *const u8) -> i32 {\n    0\n}\n\n// These functions are used by the compiler, but not\n// for a bare-bones hello world. These are normally\n// provided by libstd.\n#[lang = \"eh_personality\"]\n#[no_mangle]\npub extern fn rust_eh_personality() {\n}\n\n#[lang = \"panic_impl\"]\n#[no_mangle]\npub extern fn rust_begin_panic(info: &PanicInfo) -> ! {\n    unsafe { intrinsics::abort() }\n}\n```\n\nIn many cases, you may need to manually link to the `compiler_builtins` crate\nwhen building a `no_std` binary. You may observe this via linker error messages\nsuch as \"```undefined reference to `__rust_probestack'```\".\n\n## More about the language items\n\nThe compiler currently makes a few assumptions about symbols which are\navailable in the executable to call. Normally these functions are provided by\nthe standard library, but without it you must define your own. These symbols\nare called \"language items\", and they each have an internal name, and then a\nsignature that an implementation must conform to.\n\nThe first of these functions, `rust_eh_personality`, is used by the failure\nmechanisms of the compiler. This is often mapped to GCC's personality function\n(see the [libstd implementation][unwind] for more information), but crates\nwhich do not trigger a panic can be assured that this function is never\ncalled. The language item's name is `eh_personality`.\n\n[unwind]: https://github.com/rust-lang/rust/blob/master/src/libpanic_unwind/gcc.rs\n\nThe second function, `rust_begin_panic`, is also used by the failure mechanisms of the\ncompiler. When a panic happens, this controls the message that's displayed on\nthe screen. While the language item's name is `panic_impl`, the symbol name is\n`rust_begin_panic`.\n\nFinally, a `eh_catch_typeinfo` static is needed for certain targets which\nimplement Rust panics on top of C++ exceptions.\n\n## List of all language items\n\nThis is a list of all language items in Rust along with where they are located in\nthe source code.\n\n- Primitives\n  - `i8`: `libcore/num/mod.rs`\n  - `i16`: `libcore/num/mod.rs`\n  - `i32`: `libcore/num/mod.rs`\n  - `i64`: `libcore/num/mod.rs`\n  - `i128`: `libcore/num/mod.rs`\n  - `isize`: `libcore/num/mod.rs`\n  - `u8`: `libcore/num/mod.rs`\n  - `u16`: `libcore/num/mod.rs`\n  - `u32`: `libcore/num/mod.rs`\n  - `u64`: `libcore/num/mod.rs`\n  - `u128`: `libcore/num/mod.rs`\n  - `usize`: `libcore/num/mod.rs`\n  - `f32`: `libstd/f32.rs`\n  - `f64`: `libstd/f64.rs`\n  - `char`: `libcore/char.rs`\n  - `slice`: `liballoc/slice.rs`\n  - `str`: `liballoc/str.rs`\n  - `const_ptr`: `libcore/ptr.rs`\n  - `mut_ptr`: `libcore/ptr.rs`\n  - `unsafe_cell`: `libcore/cell.rs`\n- Runtime\n  - `start`: `libstd/rt.rs`\n  - `eh_personality`: `libpanic_unwind/emcc.rs` (EMCC)\n  - `eh_personality`: `libpanic_unwind/gcc.rs` (GNU)\n  - `eh_personality`: `libpanic_unwind/seh.rs` (SEH)\n  - `eh_catch_typeinfo`: `libpanic_unwind/emcc.rs` (EMCC)\n  - `panic`: `libcore/panicking.rs`\n  - `panic_bounds_check`: `libcore/panicking.rs`\n  - `panic_impl`: `libcore/panicking.rs`\n  - `panic_impl`: `libstd/panicking.rs`\n- Allocations\n  - `owned_box`: `liballoc/boxed.rs`\n  - `exchange_malloc`: `liballoc/heap.rs`\n  - `box_free`: `liballoc/heap.rs`\n- Operands\n  - `not`: `libcore/ops/bit.rs`\n  - `bitand`: `libcore/ops/bit.rs`\n  - `bitor`: `libcore/ops/bit.rs`\n  - `bitxor`: `libcore/ops/bit.rs`\n  - `shl`: `libcore/ops/bit.rs`\n  - `shr`: `libcore/ops/bit.rs`\n  - `bitand_assign`: `libcore/ops/bit.rs`\n  - `bitor_assign`: `libcore/ops/bit.rs`\n  - `bitxor_assign`: `libcore/ops/bit.rs`\n  - `shl_assign`: `libcore/ops/bit.rs`\n  - `shr_assign`: `libcore/ops/bit.rs`\n  - `deref`: `libcore/ops/deref.rs`\n  - `deref_mut`: `libcore/ops/deref.rs`\n  - `index`: `libcore/ops/index.rs`\n  - `index_mut`: `libcore/ops/index.rs`\n  - `add`: `libcore/ops/arith.rs`\n  - `sub`: `libcore/ops/arith.rs`\n  - `mul`: `libcore/ops/arith.rs`\n  - `div`: `libcore/ops/arith.rs`\n  - `rem`: `libcore/ops/arith.rs`\n  - `neg`: `libcore/ops/arith.rs`\n  - `add_assign`: `libcore/ops/arith.rs`\n  - `sub_assign`: `libcore/ops/arith.rs`\n  - `mul_assign`: `libcore/ops/arith.rs`\n  - `div_assign`: `libcore/ops/arith.rs`\n  - `rem_assign`: `libcore/ops/arith.rs`\n  - `eq`: `libcore/cmp.rs`\n  - `ord`: `libcore/cmp.rs`\n- Functions\n  - `fn`: `libcore/ops/function.rs`\n  - `fn_mut`: `libcore/ops/function.rs`\n  - `fn_once`: `libcore/ops/function.rs`\n  - `generator_state`: `libcore/ops/generator.rs`\n  - `generator`: `libcore/ops/generator.rs`\n- Other\n  - `coerce_unsized`: `libcore/ops/unsize.rs`\n  - `drop`: `libcore/ops/drop.rs`\n  - `drop_in_place`: `libcore/ptr.rs`\n  - `clone`: `libcore/clone.rs`\n  - `copy`: `libcore/marker.rs`\n  - `send`: `libcore/marker.rs`\n  - `sized`: `libcore/marker.rs`\n  - `unsize`: `libcore/marker.rs`\n  - `sync`: `libcore/marker.rs`\n  - `phantom_data`: `libcore/marker.rs`\n  - `discriminant_kind`: `libcore/marker.rs`\n  - `freeze`: `libcore/marker.rs`\n  - `debug_trait`: `libcore/fmt/mod.rs`\n  - `non_zero`: `libcore/nonzero.rs`\n  - `arc`: `liballoc/sync.rs`\n  - `rc`: `liballoc/rc.rs`\n" } , LintCompletion { label : "abi_msp430_interrupt" , description : "# `abi_msp430_interrupt`\n\nThe tracking issue for this feature is: [#38487]\n\n[#38487]: https://github.com/rust-lang/rust/issues/38487\n\n------------------------\n\nIn the MSP430 architecture, interrupt handlers have a special calling\nconvention. You can use the `\"msp430-interrupt\"` ABI to make the compiler apply\nthe right calling convention to the interrupt handlers you define.\n\n<!-- NOTE(ignore) this example is specific to the msp430 target -->\n\n``` rust,ignore\n#![feature(abi_msp430_interrupt)]\n#![no_std]\n\n// Place the interrupt handler at the appropriate memory address\n// (Alternatively, you can use `#[used]` and remove `pub` and `#[no_mangle]`)\n#[link_section = \"__interrupt_vector_10\"]\n#[no_mangle]\npub static TIM0_VECTOR: extern \"msp430-interrupt\" fn() = tim0;\n\n// The interrupt handler\nextern \"msp430-interrupt\" fn tim0() {\n    // ..\n}\n```\n\n``` text\n$ msp430-elf-objdump -CD ./target/msp430/release/app\nDisassembly of section __interrupt_vector_10:\n\n0000fff2 <TIM0_VECTOR>:\n    fff2:       00 c0           interrupt service routine at 0xc000\n\nDisassembly of section .text:\n\n0000c000 <int::tim0>:\n    c000:       00 13           reti\n```\n" } , LintCompletion { label : "link_args" , description : "# `link_args`\n\nThe tracking issue for this feature is: [#29596]\n\n[#29596]: https://github.com/rust-lang/rust/issues/29596\n\n------------------------\n\nYou can tell `rustc` how to customize linking, and that is via the `link_args`\nattribute. This attribute is applied to `extern` blocks and specifies raw flags\nwhich need to get passed to the linker when producing an artifact. An example\nusage would be:\n\n```rust,no_run\n#![feature(link_args)]\n\n#[link_args = \"-foo -bar -baz\"]\nextern {}\n# fn main() {}\n```\n\nNote that this feature is currently hidden behind the `feature(link_args)` gate\nbecause this is not a sanctioned way of performing linking. Right now `rustc`\nshells out to the system linker (`gcc` on most systems, `link.exe` on MSVC), so\nit makes sense to provide extra command line arguments, but this will not\nalways be the case. In the future `rustc` may use LLVM directly to link native\nlibraries, in which case `link_args` will have no meaning. You can achieve the\nsame effect as the `link_args` attribute with the `-C link-args` argument to\n`rustc`.\n\nIt is highly recommended to *not* use this attribute, and rather use the more\nformal `#[link(...)]` attribute on `extern` blocks instead.\n" } , LintCompletion { label : "const_eval_limit" , description : "# `const_eval_limit`\n\nThe tracking issue for this feature is: [#67217]\n\n[#67217]: https://github.com/rust-lang/rust/issues/67217\n\nThe `const_eval_limit` allows someone to limit the evaluation steps the CTFE undertakes to evaluate a `const fn`.\n" } , LintCompletion { label : "negative_impls" , description : "# `negative_impls`\n\nThe tracking issue for this feature is [#68318].\n\n[#68318]: https://github.com/rust-lang/rust/issues/68318\n\n----\n\nWith the feature gate `negative_impls`, you can write negative impls as well as positive ones:\n\n```rust\n#![feature(negative_impls)]\ntrait DerefMut { }\nimpl<T: ?Sized> !DerefMut for &T { }\n```\n\nNegative impls indicate a semver guarantee that the given trait will not be implemented for the given types. Negative impls play an additional purpose for auto traits, described below.\n\nNegative impls have the following characteristics:\n\n* They do not have any items.\n* They must obey the orphan rules as if they were a positive impl.\n* They cannot \"overlap\" with any positive impls.\n\n## Semver interaction\n\nIt is a breaking change to remove a negative impl. Negative impls are a commitment not to implement the given trait for the named types.\n\n## Orphan and overlap rules\n\nNegative impls must obey the same orphan rules as a positive impl. This implies you cannot add a negative impl for types defined in upstream crates and so forth.\n\nSimilarly, negative impls cannot overlap with positive impls, again using the same \"overlap\" check that we ordinarily use to determine if two impls overlap. (Note that positive impls typically cannot overlap with one another either, except as permitted by specialization.)\n\n## Interaction with auto traits\n\nDeclaring a negative impl `impl !SomeAutoTrait for SomeType` for an\nauto-trait serves two purposes:\n\n* as with any trait, it declares that `SomeType` will never implement `SomeAutoTrait`;\n* it disables the automatic `SomeType: SomeAutoTrait` impl that would otherwise have been generated.\n\nNote that, at present, there is no way to indicate that a given type\ndoes not implement an auto trait *but that it may do so in the\nfuture*. For ordinary types, this is done by simply not declaring any\nimpl at all, but that is not an option for auto traits. A workaround\nis that one could embed a marker type as one of the fields, where the\nmarker type is `!AutoTrait`.\n\n## Immediate uses\n\nNegative impls are used to declare that `&T: !DerefMut`  and `&mut T: !Clone`, as required to fix the soundness of `Pin` described in [#66544](https://github.com/rust-lang/rust/issues/66544).\n\nThis serves two purposes:\n\n* For proving the correctness of unsafe code, we can use that impl as evidence that no `DerefMut` or `Clone` impl exists.\n* It prevents downstream crates from creating such impls.\n" } , LintCompletion { label : "non_ascii_idents" , description : "# `non_ascii_idents`\n\nThe tracking issue for this feature is: [#55467]\n\n[#55467]: https://github.com/rust-lang/rust/issues/55467\n\n------------------------\n\nThe `non_ascii_idents` feature adds support for non-ASCII identifiers.\n\n## Examples\n\n```rust\n#![feature(non_ascii_idents)]\n\nconst ε: f64 = 0.00001f64;\nconst Π: f64 = 3.14f64;\n```\n\n## Changes to the language reference\n\n> **<sup>Lexer:<sup>**  \n> IDENTIFIER :  \n> &nbsp;&nbsp; &nbsp;&nbsp; XID_start XID_continue<sup>\\*</sup>  \n> &nbsp;&nbsp; | `_` XID_continue<sup>+</sup>  \n\nAn identifier is any nonempty Unicode string of the following form:\n\nEither\n\n   * The first character has property [`XID_start`]\n   * The remaining characters have property [`XID_continue`]\n\nOr\n\n   * The first character is `_`\n   * The identifier is more than one character, `_` alone is not an identifier\n   * The remaining characters have property [`XID_continue`]\n\nthat does _not_ occur in the set of [strict keywords].\n\n> **Note**: [`XID_start`] and [`XID_continue`] as character properties cover the\n> character ranges used to form the more familiar C and Java language-family\n> identifiers.\n\n[`XID_start`]:  http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Start%3A%5D&abb=on&g=&i=\n[`XID_continue`]: http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5B%3AXID_Continue%3A%5D&abb=on&g=&i=\n[strict keywords]: ../../reference/keywords.md#strict-keywords\n" } , LintCompletion { label : "transparent_unions" , description : "# `transparent_unions`\n\nThe tracking issue for this feature is [#60405]\n\n[#60405]: https://github.com/rust-lang/rust/issues/60405\n\n----\n\nThe `transparent_unions` feature allows you mark `union`s as\n`#[repr(transparent)]`. A `union` may be `#[repr(transparent)]` in exactly the\nsame conditions in which a `struct` may be `#[repr(transparent)]` (generally,\nthis means the `union` must have exactly one non-zero-sized field). Some\nconcrete illustrations follow.\n\n```rust\n#![feature(transparent_unions)]\n\n// This union has the same representation as `f32`.\n#[repr(transparent)]\nunion SingleFieldUnion {\n    field: f32,\n}\n\n// This union has the same representation as `usize`.\n#[repr(transparent)]\nunion MultiFieldUnion {\n    field: usize,\n    nothing: (),\n}\n```\n\nFor consistency with transparent `struct`s, `union`s must have exactly one\nnon-zero-sized field. If all fields are zero-sized, the `union` must not be\n`#[repr(transparent)]`:\n\n```rust\n#![feature(transparent_unions)]\n\n// This (non-transparent) union is already valid in stable Rust:\npub union GoodUnion {\n    pub nothing: (),\n}\n\n// Error: transparent union needs exactly one non-zero-sized field, but has 0\n// #[repr(transparent)]\n// pub union BadUnion {\n//     pub nothing: (),\n// }\n```\n\nThe one exception is if the `union` is generic over `T` and has a field of type\n`T`, it may be `#[repr(transparent)]` even if `T` is a zero-sized type:\n\n```rust\n#![feature(transparent_unions)]\n\n// This union has the same representation as `T`.\n#[repr(transparent)]\npub union GenericUnion<T: Copy> { // Unions with non-`Copy` fields are unstable.\n    pub field: T,\n    pub nothing: (),\n}\n\n// This is okay even though `()` is a zero-sized type.\npub const THIS_IS_OKAY: GenericUnion<()> = GenericUnion { field: () };\n```\n\nLike transarent `struct`s, a transparent `union` of type `U` has the same\nlayout, size, and ABI as its single non-ZST field. If it is generic over a type\n`T`, and all its fields are ZSTs except for exactly one field of type `T`, then\nit has the same layout and ABI as `T` (even if `T` is a ZST when monomorphized).\n\nLike transparent `struct`s, transparent `union`s are FFI-safe if and only if\ntheir underlying representation type is also FFI-safe.\n\nA `union` may not be eligible for the same nonnull-style optimizations that a\n`struct` or `enum` (with the same fields) are eligible for. Adding\n`#[repr(transparent)]` to  `union` does not change this. To give a more concrete\nexample, it is unspecified whether `size_of::<T>()` is equal to\n`size_of::<Option<T>>()`, where `T` is a `union` (regardless of whether or not\nit is transparent). The Rust compiler is free to perform this optimization if\npossible, but is not required to, and different compiler versions may differ in\ntheir application of these optimizations.\n" } , LintCompletion { label : "box_syntax" , description : "# `box_syntax`\n\nThe tracking issue for this feature is: [#49733]\n\n[#49733]: https://github.com/rust-lang/rust/issues/49733\n\nSee also [`box_patterns`](box-patterns.md)\n\n------------------------\n\nCurrently the only stable way to create a `Box` is via the `Box::new` method.\nAlso it is not possible in stable Rust to destructure a `Box` in a match\npattern. The unstable `box` keyword can be used to create a `Box`. An example\nusage would be:\n\n```rust\n#![feature(box_syntax)]\n\nfn main() {\n    let b = box 5;\n}\n```\n" } , LintCompletion { label : "repr128" , description : "# `repr128`\n\nThe tracking issue for this feature is: [#56071]\n\n[#56071]: https://github.com/rust-lang/rust/issues/56071\n\n------------------------\n\nThe `repr128` feature adds support for `#[repr(u128)]` on `enum`s.\n\n```rust\n#![feature(repr128)]\n\n#[repr(u128)]\nenum Foo {\n    Bar(u64),\n}\n```\n" } , LintCompletion { label : "member_constraints" , description : "# `member_constraints`\n\nThe tracking issue for this feature is: [#61997]\n\n[#61997]: https://github.com/rust-lang/rust/issues/61997\n\n------------------------\n\nThe `member_constraints` feature gate lets you use `impl Trait` syntax with\nmultiple unrelated lifetime parameters.\n\nA simple example is:\n\n```rust\n#![feature(member_constraints)]\n\ntrait Trait<'a, 'b> { }\nimpl<T> Trait<'_, '_> for T {}\n\nfn foo<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Trait<'a, 'b> {\n  (x, y)\n}\n\nfn main() { }\n```\n\nWithout the `member_constraints` feature gate, the above example is an\nerror because both `'a` and `'b` appear in the impl Trait bounds, but\nneither outlives the other.\n" } , LintCompletion { label : "link_cfg" , description : "# `link_cfg`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "c_variadic" , description : "# `c_variadic`\n\nThe tracking issue for this feature is: [#44930]\n\n[#44930]: https://github.com/rust-lang/rust/issues/44930\n\n------------------------\n\nThe `c_variadic` language feature enables C-variadic functions to be\ndefined in Rust. The may be called both from within Rust and via FFI.\n\n## Examples\n\n```rust\n#![feature(c_variadic)]\n\npub unsafe extern \"C\" fn add(n: usize, mut args: ...) -> usize {\n    let mut sum = 0;\n    for _ in 0..n {\n        sum += args.arg::<usize>();\n    }\n    sum\n}\n```\n" } , LintCompletion { label : "abi_ptx" , description : "# `abi_ptx`\n\nThe tracking issue for this feature is: [#38788]\n\n[#38788]: https://github.com/rust-lang/rust/issues/38788\n\n------------------------\n\nWhen emitting PTX code, all vanilla Rust functions (`fn`) get translated to\n\"device\" functions. These functions are *not* callable from the host via the\nCUDA API so a crate with only device functions is not too useful!\n\nOTOH, \"global\" functions *can* be called by the host; you can think of them\nas the real public API of your crate. To produce a global function use the\n`\"ptx-kernel\"` ABI.\n\n<!-- NOTE(ignore) this example is specific to the nvptx targets -->\n\n``` rust,ignore\n#![feature(abi_ptx)]\n#![no_std]\n\npub unsafe extern \"ptx-kernel\" fn global_function() {\n    device_function();\n}\n\npub fn device_function() {\n    // ..\n}\n```\n\n``` text\n$ xargo rustc --target nvptx64-nvidia-cuda --release -- --emit=asm\n\n$ cat $(find -name '*.s')\n//\n// Generated by LLVM NVPTX Back-End\n//\n\n.version 3.2\n.target sm_20\n.address_size 64\n\n        // .globl       _ZN6kernel15global_function17h46111ebe6516b382E\n\n.visible .entry _ZN6kernel15global_function17h46111ebe6516b382E()\n{\n\n\n        ret;\n}\n\n        // .globl       _ZN6kernel15device_function17hd6a0e4993bbf3f78E\n.visible .func _ZN6kernel15device_function17hd6a0e4993bbf3f78E()\n{\n\n\n        ret;\n}\n```\n" } , LintCompletion { label : "ffi_pure" , description : "# `ffi_pure`\n\nThe `#[ffi_pure]` attribute applies clang's `pure` attribute to foreign\nfunctions declarations.\n\nThat is, `#[ffi_pure]` functions shall have no effects except for its return\nvalue, which shall not change across two consecutive function calls with\nthe same parameters.\n\nApplying the `#[ffi_pure]` attribute to a function that violates these\nrequirements is undefined behavior.\n\nThis attribute enables Rust to perform common optimizations, like sub-expression\nelimination and loop optimizations. Some common examples of pure functions are\n`strlen` or `memcmp`.\n\nThese optimizations are only applicable when the compiler can prove that no\nprogram state observable by the `#[ffi_pure]` function has changed between calls\nof the function, which could alter the result. See also the `#[ffi_const]`\nattribute, which provides stronger guarantees regarding the allowable behavior\nof a function, enabling further optimization.\n\n## Pitfalls\n\nA `#[ffi_pure]` function can read global memory through the function\nparameters (e.g. pointers), globals, etc. `#[ffi_pure]` functions are not\nreferentially-transparent, and are therefore more relaxed than `#[ffi_const]`\nfunctions.\n\nHowever, accesing global memory through volatile or atomic reads can violate the\nrequirement that two consecutive function calls shall return the same value.\n\nA `pure` function that returns unit has no effect on the abstract machine's\nstate.\n\nA `#[ffi_pure]` function must not diverge, neither via a side effect (e.g. a\ncall to `abort`) nor by infinite loops.\n\nWhen translating C headers to Rust FFI, it is worth verifying for which targets\nthe `pure` attribute is enabled in those headers, and using the appropriate\n`cfg` macros in the Rust side to match those definitions. While the semantics of\n`pure` are implemented identically by many C and C++ compilers, e.g., clang,\n[GCC], [ARM C/C++ compiler], [IBM ILE C/C++], etc. they are not necessarily\nimplemented in this way on all of them. It is therefore also worth verifying\nthat the semantics of the C toolchain used to compile the binary being linked\nagainst are compatible with those of the `#[ffi_pure]`.\n\n\n[ARM C/C++ compiler]: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0491c/Cacigdac.html\n[GCC]: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute\n[IBM ILE C/C++]: https://www.ibm.com/support/knowledgecenter/fr/ssw_ibm_i_71/rzarg/fn_attrib_pure.htm\n" } , LintCompletion { label : "compiler_builtins" , description : "# `compiler_builtins`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "unboxed_closures" , description : "# `unboxed_closures`\n\nThe tracking issue for this feature is [#29625]\n\nSee Also: [`fn_traits`](../library-features/fn-traits.md)\n\n[#29625]: https://github.com/rust-lang/rust/issues/29625\n\n----\n\nThe `unboxed_closures` feature allows you to write functions using the `\"rust-call\"` ABI,\nrequired for implementing the [`Fn*`] family of traits. `\"rust-call\"` functions must have \nexactly one (non self) argument, a tuple representing the argument list.\n\n[`Fn*`]: https://doc.rust-lang.org/std/ops/trait.Fn.html\n\n```rust\n#![feature(unboxed_closures)]\n\nextern \"rust-call\" fn add_args(args: (u32, u32)) -> u32 {\n    args.0 + args.1\n}\n\nfn main() {}\n```\n" } , LintCompletion { label : "arbitrary_enum_discriminant" , description : "# `arbitrary_enum_discriminant`\n\nThe tracking issue for this feature is: [#60553]\n\n[#60553]: https://github.com/rust-lang/rust/issues/60553\n\n------------------------\n\nThe `arbitrary_enum_discriminant` feature permits tuple-like and\nstruct-like enum variants with `#[repr(<int-type>)]` to have explicit discriminants.\n\n## Examples\n\n```rust\n#![feature(arbitrary_enum_discriminant)]\n\n#[allow(dead_code)]\n#[repr(u8)]\nenum Enum {\n    Unit = 3,\n    Tuple(u16) = 2,\n    Struct {\n        a: u8,\n        b: u16,\n    } = 1,\n}\n\nimpl Enum {\n    fn tag(&self) -> u8 {\n        unsafe { *(self as *const Self as *const u8) }\n    }\n}\n\nassert_eq!(3, Enum::Unit.tag());\nassert_eq!(2, Enum::Tuple(5).tag());\nassert_eq!(1, Enum::Struct{a: 7, b: 11}.tag());\n```\n" } , LintCompletion { label : "marker_trait_attr" , description : "# `marker_trait_attr`\n\nThe tracking issue for this feature is: [#29864]\n\n[#29864]: https://github.com/rust-lang/rust/issues/29864\n\n------------------------\n\nNormally, Rust keeps you from adding trait implementations that could\noverlap with each other, as it would be ambiguous which to use.  This\nfeature, however, carves out an exception to that rule: a trait can\nopt-in to having overlapping implementations, at the cost that those\nimplementations are not allowed to override anything (and thus the\ntrait itself cannot have any associated items, as they're pointless\nwhen they'd need to do the same thing for every type anyway).\n\n```rust\n#![feature(marker_trait_attr)]\n\n#[marker] trait CheapToClone: Clone {}\n\nimpl<T: Copy> CheapToClone for T {}\n\n// These could potentially overlap with the blanket implementation above,\n// so are only allowed because CheapToClone is a marker trait.\nimpl<T: CheapToClone, U: CheapToClone> CheapToClone for (T, U) {}\nimpl<T: CheapToClone> CheapToClone for std::ops::Range<T> {}\n\nfn cheap_clone<T: CheapToClone>(t: T) -> T {\n    t.clone()\n}\n```\n\nThis is expected to replace the unstable `overlapping_marker_traits`\nfeature, which applied to all empty traits (without needing an opt-in).\n" } , LintCompletion { label : "plugin_registrar" , description : "# `plugin_registrar`\n\nThe tracking issue for this feature is: [#29597]\n\n[#29597]: https://github.com/rust-lang/rust/issues/29597\n\nThis feature is part of \"compiler plugins.\" It will often be used with the\n[`plugin`] and `rustc_private` features as well. For more details, see\ntheir docs.\n\n[`plugin`]: plugin.md\n\n------------------------\n" } , LintCompletion { label : "profiler_runtime" , description : "# `profiler_runtime`\n\nThe tracking issue for this feature is: [#42524](https://github.com/rust-lang/rust/issues/42524).\n\n------------------------\n" } , LintCompletion { label : "trait_alias" , description : "# `trait_alias`\n\nThe tracking issue for this feature is: [#41517]\n\n[#41517]: https://github.com/rust-lang/rust/issues/41517\n\n------------------------\n\nThe `trait_alias` feature adds support for trait aliases. These allow aliases\nto be created for one or more traits (currently just a single regular trait plus\nany number of auto-traits), and used wherever traits would normally be used as\neither bounds or trait objects.\n\n```rust\n#![feature(trait_alias)]\n\ntrait Foo = std::fmt::Debug + Send;\ntrait Bar = Foo + Sync;\n\n// Use trait alias as bound on type parameter.\nfn foo<T: Foo>(v: &T) {\n    println!(\"{:?}\", v);\n}\n\npub fn main() {\n    foo(&1);\n\n    // Use trait alias for trait objects.\n    let a: &Bar = &123;\n    println!(\"{:?}\", a);\n    let b = Box::new(456) as Box<dyn Foo>;\n    println!(\"{:?}\", b);\n}\n```\n" } , LintCompletion { label : "try_blocks" , description : "# `try_blocks`\n\nThe tracking issue for this feature is: [#31436]\n\n[#31436]: https://github.com/rust-lang/rust/issues/31436\n\n------------------------\n\nThe `try_blocks` feature adds support for `try` blocks. A `try`\nblock creates a new scope one can use the `?` operator in.\n\n```rust,edition2018\n#![feature(try_blocks)]\n\nuse std::num::ParseIntError;\n\nlet result: Result<i32, ParseIntError> = try {\n    \"1\".parse::<i32>()?\n        + \"2\".parse::<i32>()?\n        + \"3\".parse::<i32>()?\n};\nassert_eq!(result, Ok(6));\n\nlet result: Result<i32, ParseIntError> = try {\n    \"1\".parse::<i32>()?\n        + \"foo\".parse::<i32>()?\n        + \"3\".parse::<i32>()?\n};\nassert!(result.is_err());\n```\n" } , LintCompletion { label : "box_patterns" , description : "# `box_patterns`\n\nThe tracking issue for this feature is: [#29641]\n\n[#29641]: https://github.com/rust-lang/rust/issues/29641\n\nSee also [`box_syntax`](box-syntax.md)\n\n------------------------\n\nBox patterns let you match on `Box<T>`s:\n\n\n```rust\n#![feature(box_patterns)]\n\nfn main() {\n    let b = Some(Box::new(5));\n    match b {\n        Some(box n) if n < 0 => {\n            println!(\"Box contains negative number {}\", n);\n        },\n        Some(box n) if n >= 0 => {\n            println!(\"Box contains non-negative number {}\", n);\n        },\n        None => {\n            println!(\"No box\");\n        },\n        _ => unreachable!()\n    }\n}\n```\n" } , LintCompletion { label : "crate_visibility_modifier" , description : "# `crate_visibility_modifier`\n\nThe tracking issue for this feature is: [#53120]\n\n[#53120]: https://github.com/rust-lang/rust/issues/53120\n\n-----\n\nThe `crate_visibility_modifier` feature allows the `crate` keyword to be used\nas a visibility modifier synonymous to `pub(crate)`, indicating that a type\n(function, _&c._) is to be visible to the entire enclosing crate, but not to\nother crates.\n\n```rust\n#![feature(crate_visibility_modifier)]\n\ncrate struct Foo {\n    bar: usize,\n}\n```\n" } , LintCompletion { label : "allocator_internals" , description : "# `allocator_internals`\n\nThis feature does not have a tracking issue, it is an unstable implementation\ndetail of the `global_allocator` feature not intended for use outside the\ncompiler.\n\n------------------------\n" } , LintCompletion { label : "intrinsics" , description : "# `intrinsics`\n\nThe tracking issue for this feature is: None.\n\nIntrinsics are never intended to be stable directly, but intrinsics are often\nexported in some sort of stable manner. Prefer using the stable interfaces to\nthe intrinsic directly when you can.\n\n------------------------\n\n\nThese are imported as if they were FFI functions, with the special\n`rust-intrinsic` ABI. For example, if one was in a freestanding\ncontext, but wished to be able to `transmute` between types, and\nperform efficient pointer arithmetic, one would import those functions\nvia a declaration like\n\n```rust\n#![feature(intrinsics)]\n# fn main() {}\n\nextern \"rust-intrinsic\" {\n    fn transmute<T, U>(x: T) -> U;\n\n    fn offset<T>(dst: *const T, offset: isize) -> *const T;\n}\n```\n\nAs with any other FFI functions, these are always `unsafe` to call.\n\n" } , LintCompletion { label : "custom_test_frameworks" , description : "# `custom_test_frameworks`\n\nThe tracking issue for this feature is: [#50297]\n\n[#50297]: https://github.com/rust-lang/rust/issues/50297\n\n------------------------\n\nThe `custom_test_frameworks` feature allows the use of `#[test_case]` and `#![test_runner]`.\nAny function, const, or static can be annotated with `#[test_case]` causing it to be aggregated (like `#[test]`)\nand be passed to the test runner determined by the `#![test_runner]` crate attribute.\n\n```rust\n#![feature(custom_test_frameworks)]\n#![test_runner(my_runner)]\n\nfn my_runner(tests: &[&i32]) {\n    for t in tests {\n        if **t == 0 {\n            println!(\"PASSED\");\n        } else {\n            println!(\"FAILED\");\n        }\n    }\n}\n\n#[test_case]\nconst WILL_PASS: i32 = 0;\n\n#[test_case]\nconst WILL_FAIL: i32 = 4;\n```\n\n" } , LintCompletion { label : "external_doc" , description : "# `external_doc`\n\nThe tracking issue for this feature is: [#44732]\n\nThe `external_doc` feature allows the use of the `include` parameter to the `#[doc]` attribute, to\ninclude external files in documentation. Use the attribute in place of, or in addition to, regular\ndoc comments and `#[doc]` attributes, and `rustdoc` will load the given file when it renders\ndocumentation for your crate.\n\nWith the following files in the same directory:\n\n`external-doc.md`:\n\n```markdown\n# My Awesome Type\n\nThis is the documentation for this spectacular type.\n```\n\n`lib.rs`:\n\n```no_run (needs-external-files)\n#![feature(external_doc)]\n\n#[doc(include = \"external-doc.md\")]\npub struct MyAwesomeType;\n```\n\n`rustdoc` will load the file `external-doc.md` and use it as the documentation for the `MyAwesomeType`\nstruct.\n\nWhen locating files, `rustdoc` will base paths in the `src/` directory, as if they were alongside the\n`lib.rs` for your crate. So if you want a `docs/` folder to live alongside the `src/` directory,\nstart your paths with `../docs/` for `rustdoc` to properly find the file.\n\nThis feature was proposed in [RFC #1990] and initially implemented in PR [#44781].\n\n[#44732]: https://github.com/rust-lang/rust/issues/44732\n[RFC #1990]: https://github.com/rust-lang/rfcs/pull/1990\n[#44781]: https://github.com/rust-lang/rust/pull/44781\n" } , LintCompletion { label : "rustc_attrs" , description : "# `rustc_attrs`\n\nThis feature has no tracking issue, and is therefore internal to\nthe compiler, not being intended for general use.\n\nNote: `rustc_attrs` enables many rustc-internal attributes and this page\nonly discuss a few of them.\n\n------------------------\n\nThe `rustc_attrs` feature allows debugging rustc type layouts by using\n`#[rustc_layout(...)]` to debug layout at compile time (it even works\nwith `cargo check`) as an alternative to `rustc -Z print-type-sizes`\nthat is way more verbose.\n\nOptions provided by `#[rustc_layout(...)]` are `debug`, `size`, `abi`.\nNote that it only work best with sized type without generics.\n\n## Examples\n\n```rust,ignore\n#![feature(rustc_attrs)]\n\n#[rustc_layout(abi, size)]\npub enum X {\n    Y(u8, u8, u8),\n    Z(isize),\n}\n```\n\nWhen that is compiled, the compiler will error with something like\n\n```text\nerror: abi: Aggregate { sized: true }\n --> src/lib.rs:4:1\n  |\n4 | / pub enum T {\n5 | |     Y(u8, u8, u8),\n6 | |     Z(isize),\n7 | | }\n  | |_^\n\nerror: size: Size { raw: 16 }\n --> src/lib.rs:4:1\n  |\n4 | / pub enum T {\n5 | |     Y(u8, u8, u8),\n6 | |     Z(isize),\n7 | | }\n  | |_^\n\nerror: aborting due to 2 previous errors\n```\n" } , LintCompletion { label : "profiler_runtime_lib" , description : "# `profiler_runtime_lib`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "fmt_internals" , description : "# `fmt_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "libstd_io_internals" , description : "# `libstd_io_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "dec2flt" , description : "# `dec2flt`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "try_trait" , description : "# `try_trait`\n\nThe tracking issue for this feature is: [#42327]\n\n[#42327]: https://github.com/rust-lang/rust/issues/42327\n\n------------------------\n\nThis introduces a new trait `Try` for extending the `?` operator to types\nother than `Result` (a part of [RFC 1859]).  The trait provides the canonical\nway to _view_ a type in terms of a success/failure dichotomy.  This will\nallow `?` to supplant the `try_opt!` macro on `Option` and the `try_ready!`\nmacro on `Poll`, among other things.\n\n[RFC 1859]: https://github.com/rust-lang/rfcs/pull/1859\n\nHere's an example implementation of the trait:\n\n```rust,ignore\n/// A distinct type to represent the `None` value of an `Option`.\n///\n/// This enables using the `?` operator on `Option`; it's rarely useful alone.\n#[derive(Debug)]\n#[unstable(feature = \"try_trait\", issue = \"42327\")]\npub struct None { _priv: () }\n\n#[unstable(feature = \"try_trait\", issue = \"42327\")]\nimpl<T> ops::Try for Option<T>  {\n    type Ok = T;\n    type Error = None;\n\n    fn into_result(self) -> Result<T, None> {\n        self.ok_or(None { _priv: () })\n    }\n\n    fn from_ok(v: T) -> Self {\n        Some(v)\n    }\n\n    fn from_error(_: None) -> Self {\n        None\n    }\n}\n```\n\nNote the `Error` associated type here is a new marker.  The `?` operator\nallows interconversion between different `Try` implementers only when\nthe error type can be converted `Into` the error type of the enclosing\nfunction (or catch block).  Having a distinct error type (as opposed to\njust `()`, or similar) restricts this to where it's semantically meaningful.\n" } , LintCompletion { label : "windows_handle" , description : "# `windows_handle`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "windows_stdio" , description : "# `windows_stdio`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "int_error_internals" , description : "# `int_error_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "core_panic" , description : "# `core_panic`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "core_private_bignum" , description : "# `core_private_bignum`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "derive_eq" , description : "# `derive_eq`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "thread_local_internals" , description : "# `thread_local_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "print_internals" , description : "# `print_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "c_void_variant" , description : "# `c_void_variant`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "fn_traits" , description : "# `fn_traits`\n\nThe tracking issue for this feature is [#29625]\n\nSee Also: [`unboxed_closures`](../language-features/unboxed-closures.md)\n\n[#29625]: https://github.com/rust-lang/rust/issues/29625\n\n----\n\nThe `fn_traits` feature allows for implementation of the [`Fn*`] traits\nfor creating custom closure-like types.\n\n[`Fn*`]: https://doc.rust-lang.org/std/ops/trait.Fn.html\n\n```rust\n#![feature(unboxed_closures)]\n#![feature(fn_traits)]\n\nstruct Adder {\n    a: u32\n}\n\nimpl FnOnce<(u32, )> for Adder {\n    type Output = u32;\n    extern \"rust-call\" fn call_once(self, b: (u32, )) -> Self::Output {\n        self.a + b.0\n    }\n}\n\nfn main() {\n    let adder = Adder { a: 3 };\n    assert_eq!(adder(2), 5);\n}\n```\n" } , LintCompletion { label : "rt" , description : "# `rt`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "default_free_fn" , description : "# `default_free_fn`\n\nThe tracking issue for this feature is: [#73014]\n\n[#73014]: https://github.com/rust-lang/rust/issues/73014\n\n------------------------\n\nAdds a free `default()` function to the `std::default` module.  This function\njust forwards to [`Default::default()`], but may remove repetition of the word\n\"default\" from the call site.\n\nHere is an example:\n\n```rust\n#![feature(default_free_fn)]\nuse std::default::default;\n\n#[derive(Default)]\nstruct AppConfig {\n    foo: FooConfig,\n    bar: BarConfig,\n}\n\n#[derive(Default)]\nstruct FooConfig {\n    foo: i32,\n}\n\n#[derive(Default)]\nstruct BarConfig {\n    bar: f32,\n    baz: u8,\n}\n\nfn main() {\n    let options = AppConfig {\n        foo: default(),\n        bar: BarConfig {\n            bar: 10.1,\n            ..default()\n        },\n    };\n}\n```\n" } , LintCompletion { label : "update_panic_count" , description : "# `update_panic_count`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "str_internals" , description : "# `str_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "fd" , description : "# `fd`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "char_error_internals" , description : "# `char_error_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "core_intrinsics" , description : "# `core_intrinsics`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "windows_c" , description : "# `windows_c`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "libstd_sys_internals" , description : "# `libstd_sys_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "fd_read" , description : "# `fd_read`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "c_variadic" , description : "# `c_variadic`\n\nThe tracking issue for this feature is: [#44930]\n\n[#44930]: https://github.com/rust-lang/rust/issues/44930\n\n------------------------\n\nThe `c_variadic` library feature exposes the `VaList` structure,\nRust's analogue of C's `va_list` type.\n\n## Examples\n\n```rust\n#![feature(c_variadic)]\n\nuse std::ffi::VaList;\n\npub unsafe extern \"C\" fn vadd(n: usize, mut args: VaList) -> usize {\n    let mut sum = 0;\n    for _ in 0..n {\n        sum += args.arg::<usize>();\n    }\n    sum\n}\n```\n" } , LintCompletion { label : "allocator_api" , description : "# `allocator_api`\n\nThe tracking issue for this feature is [#32838]\n\n[#32838]: https://github.com/rust-lang/rust/issues/32838\n\n------------------------\n\nSometimes you want the memory for one collection to use a different\nallocator than the memory for another collection. In this case,\nreplacing the global allocator is not a workable option. Instead,\nyou need to pass in an instance of an `AllocRef` to each collection\nfor which you want a custom allocator.\n\nTBD\n" } , LintCompletion { label : "flt2dec" , description : "# `flt2dec`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "global_asm" , description : "# `global_asm`\n\nThe tracking issue for this feature is: [#35119]\n\n[#35119]: https://github.com/rust-lang/rust/issues/35119\n\n------------------------\n\nThe `global_asm!` macro allows the programmer to write arbitrary\nassembly outside the scope of a function body, passing it through\n`rustc` and `llvm` to the assembler. The macro is a no-frills\ninterface to LLVM's concept of [module-level inline assembly]. That is,\nall caveats applicable to LLVM's module-level inline assembly apply\nto `global_asm!`.\n\n[module-level inline assembly]: http://llvm.org/docs/LangRef.html#module-level-inline-assembly\n\n`global_asm!` fills a role not currently satisfied by either `asm!`\nor `#[naked]` functions. The programmer has _all_ features of the\nassembler at their disposal. The linker will expect to resolve any\nsymbols defined in the inline assembly, modulo any symbols marked as\nexternal. It also means syntax for directives and assembly follow the\nconventions of the assembler in your toolchain.\n\nA simple usage looks like this:\n\n```rust,ignore\n# #![feature(global_asm)]\n# you also need relevant target_arch cfgs\nglobal_asm!(include_str!(\"something_neato.s\"));\n```\n\nAnd a more complicated usage looks like this:\n\n```rust,ignore\n# #![feature(global_asm)]\n# #![cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n\npub mod sally {\n    global_asm!(r#\"\n        .global foo\n      foo:\n        jmp baz\n    \"#);\n\n    #[no_mangle]\n    pub unsafe extern \"C\" fn baz() {}\n}\n\n// the symbols `foo` and `bar` are global, no matter where\n// `global_asm!` was used.\nextern \"C\" {\n    fn foo();\n    fn bar();\n}\n\npub mod harry {\n    global_asm!(r#\"\n        .global bar\n      bar:\n        jmp quux\n    \"#);\n\n    #[no_mangle]\n    pub unsafe extern \"C\" fn quux() {}\n}\n```\n\nYou may use `global_asm!` multiple times, anywhere in your crate, in\nwhatever way suits you. The effect is as if you concatenated all\nusages and placed the larger, single usage in the crate root.\n\n------------------------\n\nIf you don't need quite as much power and flexibility as\n`global_asm!` provides, and you don't mind restricting your inline\nassembly to `fn` bodies only, you might try the\n[asm](asm.md) feature instead.\n" } , LintCompletion { label : "asm" , description : "# `asm`\n\nThe tracking issue for this feature is: [#72016]\n\n[#72016]: https://github.com/rust-lang/rust/issues/72016\n\n------------------------\n\nFor extremely low-level manipulations and performance reasons, one\nmight wish to control the CPU directly. Rust supports using inline\nassembly to do this via the `asm!` macro.\n\n# Guide-level explanation\n[guide-level-explanation]: #guide-level-explanation\n\nRust provides support for inline assembly via the `asm!` macro.\nIt can be used to embed handwritten assembly in the assembly output generated by the compiler.\nGenerally this should not be necessary, but might be where the required performance or timing\ncannot be otherwise achieved. Accessing low level hardware primitives, e.g. in kernel code, may also demand this functionality.\n\n> **Note**: the examples here are given in x86/x86-64 assembly, but other architectures are also supported.\n\nInline assembly is currently supported on the following architectures:\n- x86 and x86-64\n- ARM\n- AArch64\n- RISC-V\n- NVPTX\n- Hexagon\n\n## Basic usage\n\nLet us start with the simplest possible example:\n\n```rust,allow_fail\n# #![feature(asm)]\nunsafe {\n    asm!(\"nop\");\n}\n```\n\nThis will insert a NOP (no operation) instruction into the assembly generated by the compiler.\nNote that all `asm!` invocations have to be inside an `unsafe` block, as they could insert\narbitrary instructions and break various invariants. The instructions to be inserted are listed\nin the first argument of the `asm!` macro as a string literal.\n\n## Inputs and outputs\n\nNow inserting an instruction that does nothing is rather boring. Let us do something that\nactually acts on data:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet x: u64;\nunsafe {\n    asm!(\"mov {}, 5\", out(reg) x);\n}\nassert_eq!(x, 5);\n```\n\nThis will write the value `5` into the `u64` variable `x`.\nYou can see that the string literal we use to specify instructions is actually a template string.\nIt is governed by the same rules as Rust [format strings][format-syntax].\nThe arguments that are inserted into the template however look a bit different then you may\nbe familiar with. First we need to specify if the variable is an input or an output of the\ninline assembly. In this case it is an output. We declared this by writing `out`.\nWe also need to specify in what kind of register the assembly expects the variable.\nIn this case we put it in an arbitrary general purpose register by specifying `reg`.\nThe compiler will choose an appropriate register to insert into\nthe template and will read the variable from there after the inline assembly finishes executing.\n\nLet us see another example that also uses an input:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet i: u64 = 3;\nlet o: u64;\nunsafe {\n    asm!(\n        \"mov {0}, {1}\",\n        \"add {0}, {number}\",\n        out(reg) o,\n        in(reg) i,\n        number = const 5,\n    );\n}\nassert_eq!(o, 8);\n```\n\nThis will add `5` to the input in variable `i` and write the result to variable `o`.\nThe particular way this assembly does this is first copying the value from `i` to the output,\nand then adding `5` to it.\n\nThe example shows a few things:\n\nFirst, we can see that `asm!` allows multiple template string arguments; each\none is treated as a separate line of assembly code, as if they were all joined\ntogether with newlines between them. This makes it easy to format assembly\ncode.\n\nSecond, we can see that inputs are declared by writing `in` instead of `out`.\n\nThird, one of our operands has a type we haven't seen yet, `const`.\nThis tells the compiler to expand this argument to value directly inside the assembly template.\nThis is only possible for constants and literals.\n\nFourth, we can see that we can specify an argument number, or name as in any format string.\nFor inline assembly templates this is particularly useful as arguments are often used more than once.\nFor more complex inline assembly using this facility is generally recommended, as it improves\nreadability, and allows reordering instructions without changing the argument order.\n\nWe can further refine the above example to avoid the `mov` instruction:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet mut x: u64 = 3;\nunsafe {\n    asm!(\"add {0}, {number}\", inout(reg) x, number = const 5);\n}\nassert_eq!(x, 8);\n```\n\nWe can see that `inout` is used to specify an argument that is both input and output.\nThis is different from specifying an input and output separately in that it is guaranteed to assign both to the same register.\n\nIt is also possible to specify different variables for the input and output parts of an `inout` operand:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet x: u64 = 3;\nlet y: u64;\nunsafe {\n    asm!(\"add {0}, {number}\", inout(reg) x => y, number = const 5);\n}\nassert_eq!(y, 8);\n```\n\n## Late output operands\n\nThe Rust compiler is conservative with its allocation of operands. It is assumed that an `out`\ncan be written at any time, and can therefore not share its location with any other argument.\nHowever, to guarantee optimal performance it is important to use as few registers as possible,\nso they won't have to be saved and reloaded around the inline assembly block.\nTo achieve this Rust provides a `lateout` specifier. This can be used on any output that is\nwritten only after all inputs have been consumed.\nThere is also a `inlateout` variant of this specifier.\n\nHere is an example where `inlateout` *cannot* be used:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet mut a: u64 = 4;\nlet b: u64 = 4;\nlet c: u64 = 4;\nunsafe {\n    asm!(\n        \"add {0}, {1}\",\n        \"add {0}, {2}\",\n        inout(reg) a,\n        in(reg) b,\n        in(reg) c,\n    );\n}\nassert_eq!(a, 12);\n```\n\nHere the compiler is free to allocate the same register for inputs `b` and `c` since it knows they have the same value. However it must allocate a separate register for `a` since it uses `inout` and not `inlateout`. If `inlateout` was used, then `a` and `c` could be allocated to the same register, in which case the first instruction to overwrite the value of `c` and cause the assembly code to produce the wrong result.\n\nHowever the following example can use `inlateout` since the output is only modified after all input registers have been read:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet mut a: u64 = 4;\nlet b: u64 = 4;\nunsafe {\n    asm!(\"add {0}, {1}\", inlateout(reg) a, in(reg) b);\n}\nassert_eq!(a, 8);\n```\n\nAs you can see, this assembly fragment will still work correctly if `a` and `b` are assigned to the same register.\n\n## Explicit register operands\n\nSome instructions require that the operands be in a specific register.\nTherefore, Rust inline assembly provides some more specific constraint specifiers.\nWhile `reg` is generally available on any architecture, these are highly architecture specific. E.g. for x86 the general purpose registers `eax`, `ebx`, `ecx`, `edx`, `ebp`, `esi`, and `edi`\namong others can be addressed by their name.\n\n```rust,allow_fail,no_run\n# #![feature(asm)]\nlet cmd = 0xd1;\nunsafe {\n    asm!(\"out 0x64, eax\", in(\"eax\") cmd);\n}\n```\n\nIn this example we call the `out` instruction to output the content of the `cmd` variable\nto port `0x64`. Since the `out` instruction only accepts `eax` (and its sub registers) as operand\nwe had to use the `eax` constraint specifier.\n\nNote that unlike other operand types, explicit register operands cannot be used in the template string: you can't use `{}` and should write the register name directly instead. Also, they must appear at the end of the operand list after all other operand types.\n\nConsider this example which uses the x86 `mul` instruction:\n\n```rust,allow_fail\n# #![feature(asm)]\nfn mul(a: u64, b: u64) -> u128 {\n    let lo: u64;\n    let hi: u64;\n\n    unsafe {\n        asm!(\n            // The x86 mul instruction takes rax as an implicit input and writes\n            // the 128-bit result of the multiplication to rax:rdx.\n            \"mul {}\",\n            in(reg) a,\n            inlateout(\"rax\") b => lo,\n            lateout(\"rdx\") hi\n        );\n    }\n\n    ((hi as u128) << 64) + lo as u128\n}\n```\n\nThis uses the `mul` instruction to multiply two 64-bit inputs with a 128-bit result.\nThe only explicit operand is a register, that we fill from the variable `a`.\nThe second operand is implicit, and must be the `rax` register, which we fill from the variable `b`.\nThe lower 64 bits of the result are stored in `rax` from which we fill the variable `lo`.\nThe higher 64 bits are stored in `rdx` from which we fill the variable `hi`.\n\n## Clobbered registers\n\nIn many cases inline assembly will modify state that is not needed as an output.\nUsually this is either because we have to use a scratch register in the assembly,\nor instructions modify state that we don't need to further examine.\nThis state is generally referred to as being \"clobbered\".\nWe need to tell the compiler about this since it may need to save and restore this state\naround the inline assembly block.\n\n```rust,allow_fail\n# #![feature(asm)]\nlet ebx: u32;\nlet ecx: u32;\n\nunsafe {\n    asm!(\n        \"cpuid\",\n        // EAX 4 selects the \"Deterministic Cache Parameters\" CPUID leaf\n        inout(\"eax\") 4 => _,\n        // ECX 0 selects the L0 cache information.\n        inout(\"ecx\") 0 => ecx,\n        lateout(\"ebx\") ebx,\n        lateout(\"edx\") _,\n    );\n}\n\nprintln!(\n    \"L1 Cache: {}\",\n    ((ebx >> 22) + 1) * (((ebx >> 12) & 0x3ff) + 1) * ((ebx & 0xfff) + 1) * (ecx + 1)\n);\n```\n\nIn the example above we use the `cpuid` instruction to get the L1 cache size.\nThis instruction writes to `eax`, `ebx`, `ecx`, and `edx`, but for the cache size we only care about the contents of `ebx` and `ecx`.\n\nHowever we still need to tell the compiler that `eax` and `edx` have been modified so that it can save any values that were in these registers before the asm. This is done by declaring these as outputs but with `_` instead of a variable name, which indicates that the output value is to be discarded.\n\nThis can also be used with a general register class (e.g. `reg`) to obtain a scratch register for use inside the asm code:\n\n```rust,allow_fail\n# #![feature(asm)]\n// Multiply x by 6 using shifts and adds\nlet mut x: u64 = 4;\nunsafe {\n    asm!(\n        \"mov {tmp}, {x}\",\n        \"shl {tmp}, 1\",\n        \"shl {x}, 2\",\n        \"add {x}, {tmp}\",\n        x = inout(reg) x,\n        tmp = out(reg) _,\n    );\n}\nassert_eq!(x, 4 * 6);\n```\n\n## Symbol operands\n\nA special operand type, `sym`, allows you to use the symbol name of a `fn` or `static` in inline assembly code.\nThis allows you to call a function or access a global variable without needing to keep its address in a register.\n\n```rust,allow_fail\n# #![feature(asm)]\nextern \"C\" fn foo(arg: i32) {\n    println!(\"arg = {}\", arg);\n}\n\nfn call_foo(arg: i32) {\n    unsafe {\n        asm!(\n            \"call {}\",\n            sym foo,\n            // 1st argument in rdi, which is caller-saved\n            inout(\"rdi\") arg => _,\n            // All caller-saved registers must be marked as clobberred\n            out(\"rax\") _, out(\"rcx\") _, out(\"rdx\") _, out(\"rsi\") _,\n            out(\"r8\") _, out(\"r9\") _, out(\"r10\") _, out(\"r11\") _,\n            out(\"xmm0\") _, out(\"xmm1\") _, out(\"xmm2\") _, out(\"xmm3\") _,\n            out(\"xmm4\") _, out(\"xmm5\") _, out(\"xmm6\") _, out(\"xmm7\") _,\n            out(\"xmm8\") _, out(\"xmm9\") _, out(\"xmm10\") _, out(\"xmm11\") _,\n            out(\"xmm12\") _, out(\"xmm13\") _, out(\"xmm14\") _, out(\"xmm15\") _,\n        )\n    }\n}\n```\n\nNote that the `fn` or `static` item does not need to be public or `#[no_mangle]`:\nthe compiler will automatically insert the appropriate mangled symbol name into the assembly code.\n\n## Register template modifiers\n\nIn some cases, fine control is needed over the way a register name is formatted when inserted into the template string. This is needed when an architecture's assembly language has several names for the same register, each typically being a \"view\" over a subset of the register (e.g. the low 32 bits of a 64-bit register).\n\nBy default the compiler will always choose the name that refers to the full register size (e.g. `rax` on x86-64, `eax` on x86, etc).\n\nThis default can be overriden by using modifiers on the template string operands, just like you would with format strings:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet mut x: u16 = 0xab;\n\nunsafe {\n    asm!(\"mov {0:h}, {0:l}\", inout(reg_abcd) x);\n}\n\nassert_eq!(x, 0xabab);\n```\n\nIn this example, we use the `reg_abcd` register class to restrict the register allocator to the 4 legacy x86 register (`ax`, `bx`, `cx`, `dx`) of which the first two bytes can be addressed independently.\n\nLet us assume that the register allocator has chosen to allocate `x` in the `ax` register.\nThe `h` modifier will emit the register name for the high byte of that register and the `l` modifier will emit the register name for the low byte. The asm code will therefore be expanded as `mov ah, al` which copies the low byte of the value into the high byte.\n\nIf you use a smaller data type (e.g. `u16`) with an operand and forget the use template modifiers, the compiler will emit a warning and suggest the correct modifier to use.\n\n## Options\n\nBy default, an inline assembly block is treated the same way as an external FFI function call with a custom calling convention: it may read/write memory, have observable side effects, etc. However in many cases, it is desirable to give the compiler more information about what the assembly code is actually doing so that it can optimize better.\n\nLet's take our previous example of an `add` instruction:\n\n```rust,allow_fail\n# #![feature(asm)]\nlet mut a: u64 = 4;\nlet b: u64 = 4;\nunsafe {\n    asm!(\n        \"add {0}, {1}\",\n        inlateout(reg) a, in(reg) b,\n        options(pure, nomem, nostack),\n    );\n}\nassert_eq!(a, 8);\n```\n\nOptions can be provided as an optional final argument to the `asm!` macro. We specified three options here:\n- `pure` means that the asm code has no observable side effects and that its output depends only on its inputs. This allows the compiler optimizer to call the inline asm fewer times or even eliminate it entirely.\n- `nomem` means that the asm code does not read or write to memory. By default the compiler will assume that inline assembly can read or write any memory address that is accessible to it (e.g. through a pointer passed as an operand, or a global).\n- `nostack` means that the asm code does not push any data onto the stack. This allows the compiler to use optimizations such as the stack red zone on x86-64 to avoid stack pointer adjustments.\n\nThese allow the compiler to better optimize code using `asm!`, for example by eliminating pure `asm!` blocks whose outputs are not needed.\n\nSee the reference for the full list of available options and their effects.\n\n# Reference-level explanation\n[reference-level-explanation]: #reference-level-explanation\n\nInline assembler is implemented as an unsafe macro `asm!()`.\nThe first argument to this macro is a template string literal used to build the final assembly.\nThe following arguments specify input and output operands.\nWhen required, options are specified as the final argument.\n\nThe following ABNF specifies the general syntax:\n\n```ignore\ndir_spec := \"in\" / \"out\" / \"lateout\" / \"inout\" / \"inlateout\"\nreg_spec := <register class> / \"<explicit register>\"\noperand_expr := expr / \"_\" / expr \"=>\" expr / expr \"=>\" \"_\"\nreg_operand := dir_spec \"(\" reg_spec \")\" operand_expr\noperand := reg_operand / \"const\" const_expr / \"sym\" path\noption := \"pure\" / \"nomem\" / \"readonly\" / \"preserves_flags\" / \"noreturn\" / \"att_syntax\"\noptions := \"options(\" option *[\",\" option] [\",\"] \")\"\nasm := \"asm!(\" format_string *(\",\" format_string) *(\",\" [ident \"=\"] operand) [\",\" options] [\",\"] \")\"\n```\n\nThe macro will initially be supported only on ARM, AArch64, Hexagon, x86, x86-64 and RISC-V targets. Support for more targets may be added in the future. The compiler will emit an error if `asm!` is used on an unsupported target.\n\n[format-syntax]: https://doc.rust-lang.org/std/fmt/#syntax\n\n## Template string arguments\n\nThe assembler template uses the same syntax as [format strings][format-syntax] (i.e. placeholders are specified by curly braces). The corresponding arguments are accessed in order, by index, or by name. However, implicit named arguments (introduced by [RFC #2795][rfc-2795]) are not supported.\n\nAn `asm!` invocation may have one or more template string arguments; an `asm!` with multiple template string arguments is treated as if all the strings were concatenated with a `\\n` between them. The expected usage is for each template string argument to correspond to a line of assembly code. All template string arguments must appear before any other arguments.\n\nAs with format strings, named arguments must appear after positional arguments. Explicit register operands must appear at the end of the operand list, after named arguments if any.\n\nExplicit register operands cannot be used by placeholders in the template string. All other named and positional operands must appear at least once in the template string, otherwise a compiler error is generated.\n\nThe exact assembly code syntax is target-specific and opaque to the compiler except for the way operands are substituted into the template string to form the code passed to the assembler.\n\nThe 5 targets specified in this RFC (x86, ARM, AArch64, RISC-V, Hexagon) all use the assembly code syntax of the GNU assembler (GAS). On x86, the `.intel_syntax noprefix` mode of GAS is used by default. On ARM, the `.syntax unified` mode is used. These targets impose an additional restriction on the assembly code: any assembler state (e.g. the current section which can be changed with `.section`) must be restored to its original value at the end of the asm string. Assembly code that does not conform to the GAS syntax will result in assembler-specific behavior.\n\n[rfc-2795]: https://github.com/rust-lang/rfcs/pull/2795\n\n## Operand type\n\nSeveral types of operands are supported:\n\n* `in(<reg>) <expr>`\n  - `<reg>` can refer to a register class or an explicit register. The allocated register name is substituted into the asm template string.\n  - The allocated register will contain the value of `<expr>` at the start of the asm code.\n  - The allocated register must contain the same value at the end of the asm code (except if a `lateout` is allocated to the same register).\n* `out(<reg>) <expr>`\n  - `<reg>` can refer to a register class or an explicit register. The allocated register name is substituted into the asm template string.\n  - The allocated register will contain an undefined value at the start of the asm code.\n  - `<expr>` must be a (possibly uninitialized) place expression, to which the contents of the allocated register is written to at the end of the asm code.\n  - An underscore (`_`) may be specified instead of an expression, which will cause the contents of the register to be discarded at the end of the asm code (effectively acting as a clobber).\n* `lateout(<reg>) <expr>`\n  - Identical to `out` except that the register allocator can reuse a register allocated to an `in`.\n  - You should only write to the register after all inputs are read, otherwise you may clobber an input.\n* `inout(<reg>) <expr>`\n  - `<reg>` can refer to a register class or an explicit register. The allocated register name is substituted into the asm template string.\n  - The allocated register will contain the value of `<expr>` at the start of the asm code.\n  - `<expr>` must be a mutable initialized place expression, to which the contents of the allocated register is written to at the end of the asm code.\n* `inout(<reg>) <in expr> => <out expr>`\n  - Same as `inout` except that the initial value of the register is taken from the value of `<in expr>`.\n  - `<out expr>` must be a (possibly uninitialized) place expression, to which the contents of the allocated register is written to at the end of the asm code.\n  - An underscore (`_`) may be specified instead of an expression for `<out expr>`, which will cause the contents of the register to be discarded at the end of the asm code (effectively acting as a clobber).\n  - `<in expr>` and `<out expr>` may have different types.\n* `inlateout(<reg>) <expr>` / `inlateout(<reg>) <in expr> => <out expr>`\n  - Identical to `inout` except that the register allocator can reuse a register allocated to an `in` (this can happen if the compiler knows the `in` has the same initial value as the `inlateout`).\n  - You should only write to the register after all inputs are read, otherwise you may clobber an input.\n* `const <expr>`\n  - `<expr>` must be an integer or floating-point constant expression.\n  - The value of the expression is formatted as a string and substituted directly into the asm template string.\n* `sym <path>`\n  - `<path>` must refer to a `fn` or `static`.\n  - A mangled symbol name referring to the item is substituted into the asm template string.\n  - The substituted string does not include any modifiers (e.g. GOT, PLT, relocations, etc).\n  - `<path>` is allowed to point to a `#[thread_local]` static, in which case the asm code can combine the symbol with relocations (e.g. `@plt`, `@TPOFF`) to read from thread-local data.\n\nOperand expressions are evaluated from left to right, just like function call arguments. After the `asm!` has executed, outputs are written to in left to right order. This is significant if two outputs point to the same place: that place will contain the value of the rightmost output.\n\n## Register operands\n\nInput and output operands can be specified either as an explicit register or as a register class from which the register allocator can select a register. Explicit registers are specified as string literals (e.g. `\"eax\"`) while register classes are specified as identifiers (e.g. `reg`). Using string literals for register names enables support for architectures that use special characters in register names, such as MIPS (`$0`, `$1`, etc).\n\nNote that explicit registers treat register aliases (e.g. `r14` vs `lr` on ARM) and smaller views of a register (e.g. `eax` vs `rax`) as equivalent to the base register. It is a compile-time error to use the same explicit register for two input operands or two output operands. Additionally, it is also a compile-time error to use overlapping registers (e.g. ARM VFP) in input operands or in output operands.\n\nOnly the following types are allowed as operands for inline assembly:\n- Integers (signed and unsigned)\n- Floating-point numbers\n- Pointers (thin only)\n- Function pointers\n- SIMD vectors (structs defined with `#[repr(simd)]` and which implement `Copy`). This includes architecture-specific vector types defined in `std::arch` such as `__m128` (x86) or `int8x16_t` (ARM).\n\nHere is the list of currently supported register classes:\n\n| Architecture | Register class | Registers | LLVM constraint code |\n| ------------ | -------------- | --------- | -------------------- |\n| x86 | `reg` | `ax`, `bx`, `cx`, `dx`, `si`, `di`, `r[8-15]` (x86-64 only) | `r` |\n| x86 | `reg_abcd` | `ax`, `bx`, `cx`, `dx` | `Q` |\n| x86-32 | `reg_byte` | `al`, `bl`, `cl`, `dl`, `ah`, `bh`, `ch`, `dh` | `q` |\n| x86-64 | `reg_byte` | `al`, `bl`, `cl`, `dl`, `sil`, `dil`, `r[8-15]b`, `ah`\\*, `bh`\\*, `ch`\\*, `dh`\\* | `q` |\n| x86 | `xmm_reg` | `xmm[0-7]` (x86) `xmm[0-15]` (x86-64) | `x` |\n| x86 | `ymm_reg` | `ymm[0-7]` (x86) `ymm[0-15]` (x86-64) | `x` |\n| x86 | `zmm_reg` | `zmm[0-7]` (x86) `zmm[0-31]` (x86-64) | `v` |\n| x86 | `kreg` | `k[1-7]` | `Yk` |\n| AArch64 | `reg` | `x[0-28]`, `x30` | `r` |\n| AArch64 | `vreg` | `v[0-31]` | `w` |\n| AArch64 | `vreg_low16` | `v[0-15]` | `x` |\n| ARM | `reg` | `r[0-5]` `r7`\\*, `r[8-10]`, `r11`\\*, `r12`, `r14` | `r` |\n| ARM (Thumb) | `reg_thumb` | `r[0-r7]` | `l` |\n| ARM (ARM) | `reg_thumb` | `r[0-r10]`, `r12`, `r14` | `l` |\n| ARM | `sreg` | `s[0-31]` | `t` |\n| ARM | `sreg_low16` | `s[0-15]` | `x` |\n| ARM | `dreg` | `d[0-31]` | `w` |\n| ARM | `dreg_low16` | `d[0-15]` | `t` |\n| ARM | `dreg_low8` | `d[0-8]` | `x` |\n| ARM | `qreg` | `q[0-15]` | `w` |\n| ARM | `qreg_low8` | `q[0-7]` | `t` |\n| ARM | `qreg_low4` | `q[0-3]` | `x` |\n| NVPTX | `reg16` | None\\* | `h` |\n| NVPTX | `reg32` | None\\* | `r` |\n| NVPTX | `reg64` | None\\* | `l` |\n| RISC-V | `reg` | `x1`, `x[5-7]`, `x[9-15]`, `x[16-31]` (non-RV32E) | `r` |\n| RISC-V | `freg` | `f[0-31]` | `f` |\n| Hexagon | `reg` | `r[0-28]` | `r` |\n\n> **Note**: On x86 we treat `reg_byte` differently from `reg` because the compiler can allocate `al` and `ah` separately whereas `reg` reserves the whole register.\n>\n> Note #2: On x86-64 the high byte registers (e.g. `ah`) are only available when used as an explicit register. Specifying the `reg_byte` register class for an operand will always allocate a low byte register.\n>\n> Note #3: NVPTX doesn't have a fixed register set, so named registers are not supported.\n>\n> Note #4: On ARM the frame pointer is either `r7` or `r11` depending on the platform.\n\nAdditional register classes may be added in the future based on demand (e.g. MMX, x87, etc).\n\nEach register class has constraints on which value types they can be used with. This is necessary because the way a value is loaded into a register depends on its type. For example, on big-endian systems, loading a `i32x4` and a `i8x16` into a SIMD register may result in different register contents even if the byte-wise memory representation of both values is identical. The availability of supported types for a particular register class may depend on what target features are currently enabled.\n\n| Architecture | Register class | Target feature | Allowed types |\n| ------------ | -------------- | -------------- | ------------- |\n| x86-32 | `reg` | None | `i16`, `i32`, `f32` |\n| x86-64 | `reg` | None | `i16`, `i32`, `f32`, `i64`, `f64` |\n| x86 | `reg_byte` | None | `i8` |\n| x86 | `xmm_reg` | `sse` | `i32`, `f32`, `i64`, `f64`, <br> `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4`, `f64x2` |\n| x86 | `ymm_reg` | `avx` | `i32`, `f32`, `i64`, `f64`, <br> `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4`, `f64x2` <br> `i8x32`, `i16x16`, `i32x8`, `i64x4`, `f32x8`, `f64x4` |\n| x86 | `zmm_reg` | `avx512f` | `i32`, `f32`, `i64`, `f64`, <br> `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4`, `f64x2` <br> `i8x32`, `i16x16`, `i32x8`, `i64x4`, `f32x8`, `f64x4` <br> `i8x64`, `i16x32`, `i32x16`, `i64x8`, `f32x16`, `f64x8` |\n| x86 | `kreg` | `axv512f` | `i8`, `i16` |\n| x86 | `kreg` | `axv512bw` | `i32`, `i64` |\n| AArch64 | `reg` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |\n| AArch64 | `vreg` | `fp` | `i8`, `i16`, `i32`, `f32`, `i64`, `f64`, <br> `i8x8`, `i16x4`, `i32x2`, `i64x1`, `f32x2`, `f64x1`, <br> `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4`, `f64x2` |\n| ARM | `reg` | None | `i8`, `i16`, `i32`, `f32` |\n| ARM | `sreg` | `vfp2` | `i32`, `f32` |\n| ARM | `dreg` | `vfp2` | `i64`, `f64`, `i8x8`, `i16x4`, `i32x2`, `i64x1`, `f32x2` |\n| ARM | `qreg` | `neon` | `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4` |\n| NVPTX | `reg16` | None | `i8`, `i16` |\n| NVPTX | `reg32` | None | `i8`, `i16`, `i32`, `f32` |\n| NVPTX | `reg64` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |\n| RISC-V32 | `reg` | None | `i8`, `i16`, `i32`, `f32` |\n| RISC-V64 | `reg` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |\n| RISC-V | `freg` | `f` | `f32` |\n| RISC-V | `freg` | `d` | `f64` |\n| Hexagon | `reg` | None | `i8`, `i16`, `i32`, `f32` |\n\n> **Note**: For the purposes of the above table pointers, function pointers and `isize`/`usize` are treated as the equivalent integer type (`i16`/`i32`/`i64` depending on the target).\n\nIf a value is of a smaller size than the register it is allocated in then the upper bits of that register will have an undefined value for inputs and will be ignored for outputs. The only exception is the `freg` register class on RISC-V where `f32` values are NaN-boxed in a `f64` as required by the RISC-V architecture.\n\nWhen separate input and output expressions are specified for an `inout` operand, both expressions must have the same type. The only exception is if both operands are pointers or integers, in which case they are only required to have the same size. This restriction exists because the register allocators in LLVM and GCC sometimes cannot handle tied operands with different types.\n\n## Register names\n\nSome registers have multiple names. These are all treated by the compiler as identical to the base register name. Here is the list of all supported register aliases:\n\n| Architecture | Base register | Aliases |\n| ------------ | ------------- | ------- |\n| x86 | `ax` | `eax`, `rax` |\n| x86 | `bx` | `ebx`, `rbx` |\n| x86 | `cx` | `ecx`, `rcx` |\n| x86 | `dx` | `edx`, `rdx` |\n| x86 | `si` | `esi`, `rsi` |\n| x86 | `di` | `edi`, `rdi` |\n| x86 | `bp` | `bpl`, `ebp`, `rbp` |\n| x86 | `sp` | `spl`, `esp`, `rsp` |\n| x86 | `ip` | `eip`, `rip` |\n| x86 | `st(0)` | `st` |\n| x86 | `r[8-15]` | `r[8-15]b`, `r[8-15]w`, `r[8-15]d` |\n| x86 | `xmm[0-31]` | `ymm[0-31]`, `zmm[0-31]` |\n| AArch64 | `x[0-30]` | `w[0-30]` |\n| AArch64 | `x29` | `fp` |\n| AArch64 | `x30` | `lr` |\n| AArch64 | `sp` | `wsp` |\n| AArch64 | `xzr` | `wzr` |\n| AArch64 | `v[0-31]` | `b[0-31]`, `h[0-31]`, `s[0-31]`, `d[0-31]`, `q[0-31]` |\n| ARM | `r[0-3]` | `a[1-4]` |\n| ARM | `r[4-9]` | `v[1-6]` |\n| ARM | `r9` | `rfp` |\n| ARM | `r10` | `sl` |\n| ARM | `r11` | `fp` |\n| ARM | `r12` | `ip` |\n| ARM | `r13` | `sp` |\n| ARM | `r14` | `lr` |\n| ARM | `r15` | `pc` |\n| RISC-V | `x0` | `zero` |\n| RISC-V | `x1` | `ra` |\n| RISC-V | `x2` | `sp` |\n| RISC-V | `x3` | `gp` |\n| RISC-V | `x4` | `tp` |\n| RISC-V | `x[5-7]` | `t[0-2]` |\n| RISC-V | `x8` | `fp`, `s0` |\n| RISC-V | `x9` | `s1` |\n| RISC-V | `x[10-17]` | `a[0-7]` |\n| RISC-V | `x[18-27]` | `s[2-11]` |\n| RISC-V | `x[28-31]` | `t[3-6]` |\n| RISC-V | `f[0-7]` | `ft[0-7]` |\n| RISC-V | `f[8-9]` | `fs[0-1]` |\n| RISC-V | `f[10-17]` | `fa[0-7]` |\n| RISC-V | `f[18-27]` | `fs[2-11]` |\n| RISC-V | `f[28-31]` | `ft[8-11]` |\n| Hexagon | `r29` | `sp` |\n| Hexagon | `r30` | `fr` |\n| Hexagon | `r31` | `lr` |\n\nSome registers cannot be used for input or output operands:\n\n| Architecture | Unsupported register | Reason |\n| ------------ | -------------------- | ------ |\n| All | `sp` | The stack pointer must be restored to its original value at the end of an asm code block. |\n| All | `bp` (x86), `x29` (AArch64), `x8` (RISC-V), `fr` (Hexagon) | The frame pointer cannot be used as an input or output. |\n| ARM | `r7` or `r11` | On ARM the frame pointer can be either `r7` or `r11` depending on the target. The frame pointer cannot be used as an input or output. |\n| ARM | `r6` | `r6` is used internally by LLVM as a base pointer and therefore cannot be used as an input or output. |\n| x86 | `k0` | This is a constant zero register which can't be modified. |\n| x86 | `ip` | This is the program counter, not a real register. |\n| x86 | `mm[0-7]` | MMX registers are not currently supported (but may be in the future). |\n| x86 | `st([0-7])` | x87 registers are not currently supported (but may be in the future). |\n| AArch64 | `xzr` | This is a constant zero register which can't be modified. |\n| ARM | `pc` | This is the program counter, not a real register. |\n| RISC-V | `x0` | This is a constant zero register which can't be modified. |\n| RISC-V | `gp`, `tp` | These registers are reserved and cannot be used as inputs or outputs. |\n| Hexagon | `lr` | This is the link register which cannot be used as an input or output. |\n\nIn some cases LLVM will allocate a \"reserved register\" for `reg` operands even though this register cannot be explicitly specified. Assembly code making use of reserved registers should be careful since `reg` operands may alias with those registers. Reserved registers are:\n- The frame pointer on all architectures.\n- `r6` on ARM.\n\n## Template modifiers\n\nThe placeholders can be augmented by modifiers which are specified after the `:` in the curly braces. These modifiers do not affect register allocation, but change the way operands are formatted when inserted into the template string. Only one modifier is allowed per template placeholder.\n\nThe supported modifiers are a subset of LLVM's (and GCC's) [asm template argument modifiers][llvm-argmod], but do not use the same letter codes.\n\n| Architecture | Register class | Modifier | Example output | LLVM modifier |\n| ------------ | -------------- | -------- | -------------- | ------------- |\n| x86-32 | `reg` | None | `eax` | `k` |\n| x86-64 | `reg` | None | `rax` | `q` |\n| x86-32 | `reg_abcd` | `l` | `al` | `b` |\n| x86-64 | `reg` | `l` | `al` | `b` |\n| x86 | `reg_abcd` | `h` | `ah` | `h` |\n| x86 | `reg` | `x` | `ax` | `w` |\n| x86 | `reg` | `e` | `eax` | `k` |\n| x86-64 | `reg` | `r` | `rax` | `q` |\n| x86 | `reg_byte` | None | `al` / `ah` | None |\n| x86 | `xmm_reg` | None | `xmm0` | `x` |\n| x86 | `ymm_reg` | None | `ymm0` | `t` |\n| x86 | `zmm_reg` | None | `zmm0` | `g` |\n| x86 | `*mm_reg` | `x` | `xmm0` | `x` |\n| x86 | `*mm_reg` | `y` | `ymm0` | `t` |\n| x86 | `*mm_reg` | `z` | `zmm0` | `g` |\n| x86 | `kreg` | None | `k1` | None |\n| AArch64 | `reg` | None | `x0` | `x` |\n| AArch64 | `reg` | `w` | `w0` | `w` |\n| AArch64 | `reg` | `x` | `x0` | `x` |\n| AArch64 | `vreg` | None | `v0` | None |\n| AArch64 | `vreg` | `v` | `v0` | None |\n| AArch64 | `vreg` | `b` | `b0` | `b` |\n| AArch64 | `vreg` | `h` | `h0` | `h` |\n| AArch64 | `vreg` | `s` | `s0` | `s` |\n| AArch64 | `vreg` | `d` | `d0` | `d` |\n| AArch64 | `vreg` | `q` | `q0` | `q` |\n| ARM | `reg` | None | `r0` | None |\n| ARM | `sreg` | None | `s0` | None |\n| ARM | `dreg` | None | `d0` | `P` |\n| ARM | `qreg` | None | `q0` | `q` |\n| ARM | `qreg` | `e` / `f` | `d0` / `d1` | `e` / `f` |\n| NVPTX | `reg16` | None | `rs0` | None |\n| NVPTX | `reg32` | None | `r0` | None |\n| NVPTX | `reg64` | None | `rd0` | None |\n| RISC-V | `reg` | None | `x1` | None |\n| RISC-V | `freg` | None | `f0` | None |\n| Hexagon | `reg` | None | `r0` | None |\n\n> Notes:\n> - on ARM `e` / `f`: this prints the low or high doubleword register name of a NEON quad (128-bit) register.\n> - on x86: our behavior for `reg` with no modifiers differs from what GCC does. GCC will infer the modifier based on the operand value type, while we default to the full register size.\n> - on x86 `xmm_reg`: the `x`, `t` and `g` LLVM modifiers are not yet implemented in LLVM (they are supported by GCC only), but this should be a simple change.\n\nAs stated in the previous section, passing an input value smaller than the register width will result in the upper bits of the register containing undefined values. This is not a problem if the inline asm only accesses the lower bits of the register, which can be done by using a template modifier to use a subregister name in the asm code (e.g. `ax` instead of `rax`). Since this an easy pitfall, the compiler will suggest a template modifier to use where appropriate given the input type. If all references to an operand already have modifiers then the warning is suppressed for that operand.\n\n[llvm-argmod]: http://llvm.org/docs/LangRef.html#asm-template-argument-modifiers\n\n## Options\n\nFlags are used to further influence the behavior of the inline assembly block.\nCurrently the following options are defined:\n- `pure`: The `asm` block has no side effects, and its outputs depend only on its direct inputs (i.e. the values themselves, not what they point to) or values read from memory (unless the `nomem` options is also set). This allows the compiler to execute the `asm` block fewer times than specified in the program (e.g. by hoisting it out of a loop) or even eliminate it entirely if the outputs are not used.\n- `nomem`: The `asm` blocks does not read or write to any memory. This allows the compiler to cache the values of modified global variables in registers across the `asm` block since it knows that they are not read or written to by the `asm`.\n- `readonly`: The `asm` block does not write to any memory. This allows the compiler to cache the values of unmodified global variables in registers across the `asm` block since it knows that they are not written to by the `asm`.\n- `preserves_flags`: The `asm` block does not modify the flags register (defined in the rules below). This allows the compiler to avoid recomputing the condition flags after the `asm` block.\n- `noreturn`: The `asm` block never returns, and its return type is defined as `!` (never). Behavior is undefined if execution falls through past the end of the asm code. A `noreturn` asm block behaves just like a function which doesn't return; notably, local variables in scope are not dropped before it is invoked.\n- `nostack`: The `asm` block does not push data to the stack, or write to the stack red-zone (if supported by the target). If this option is *not* used then the stack pointer is guaranteed to be suitably aligned (according to the target ABI) for a function call.\n- `att_syntax`: This option is only valid on x86, and causes the assembler to use the `.att_syntax prefix` mode of the GNU assembler. Register operands are substituted in with a leading `%`.\n\nThe compiler performs some additional checks on options:\n- The `nomem` and `readonly` options are mutually exclusive: it is a compile-time error to specify both.\n- The `pure` option must be combined with either the `nomem` or `readonly` options, otherwise a compile-time error is emitted.\n- It is a compile-time error to specify `pure` on an asm block with no outputs or only discarded outputs (`_`).\n- It is a compile-time error to specify `noreturn` on an asm block with outputs.\n\n## Rules for inline assembly\n\n- Any registers not specified as inputs will contain an undefined value on entry to the asm block.\n  - An \"undefined value\" in the context of inline assembly means that the register can (non-deterministically) have any one of the possible values allowed by the architecture. Notably it is not the same as an LLVM `undef` which can have a different value every time you read it (since such a concept does not exist in assembly code).\n- Any registers not specified as outputs must have the same value upon exiting the asm block as they had on entry, otherwise behavior is undefined.\n  - This only applies to registers which can be specified as an input or output. Other registers follow target-specific rules.\n  - Note that a `lateout` may be allocated to the same register as an `in`, in which case this rule does not apply. Code should not rely on this however since it depends on the results of register allocation.\n- Behavior is undefined if execution unwinds out of an asm block.\n  - This also applies if the assembly code calls a function which then unwinds.\n- The set of memory locations that assembly code is allowed the read and write are the same as those allowed for an FFI function.\n  - Refer to the unsafe code guidelines for the exact rules.\n  - If the `readonly` option is set, then only memory reads are allowed.\n  - If the `nomem` option is set then no reads or writes to memory are allowed.\n  - These rules do not apply to memory which is private to the asm code, such as stack space allocated within the asm block.\n- The compiler cannot assume that the instructions in the asm are the ones that will actually end up executed.\n  - This effectively means that the compiler must treat the `asm!` as a black box and only take the interface specification into account, not the instructions themselves.\n  - Runtime code patching is allowed, via target-specific mechanisms (outside the scope of this RFC).\n- Unless the `nostack` option is set, asm code is allowed to use stack space below the stack pointer.\n  - On entry to the asm block the stack pointer is guaranteed to be suitably aligned (according to the target ABI) for a function call.\n  - You are responsible for making sure you don't overflow the stack (e.g. use stack probing to ensure you hit a guard page).\n  - You should adjust the stack pointer when allocating stack memory as required by the target ABI.\n  - The stack pointer must be restored to its original value before leaving the asm block.\n- If the `noreturn` option is set then behavior is undefined if execution falls through to the end of the asm block.\n- If the `pure` option is set then behavior is undefined if the `asm` has side-effects other than its direct outputs. Behavior is also undefined if two executions of the `asm` code with the same inputs result in different outputs.\n  - When used with the `nomem` option, \"inputs\" are just the direct inputs of the `asm!`.\n  - When used with the `readonly` option, \"inputs\" comprise the direct inputs of the `asm!` and any memory that the `asm!` block is allowed to read.\n- These flags registers must be restored upon exiting the asm block if the `preserves_flags` option is set:\n  - x86\n    - Status flags in `EFLAGS` (CF, PF, AF, ZF, SF, OF).\n    - Floating-point status word (all).\n    - Floating-point exception flags in `MXCSR` (PE, UE, OE, ZE, DE, IE).\n  - ARM\n    - Condition flags in `CPSR` (N, Z, C, V)\n    - Saturation flag in `CPSR` (Q)\n    - Greater than or equal flags in `CPSR` (GE).\n    - Condition flags in `FPSCR` (N, Z, C, V)\n    - Saturation flag in `FPSCR` (QC)\n    - Floating-point exception flags in `FPSCR` (IDC, IXC, UFC, OFC, DZC, IOC).\n  - AArch64\n    - Condition flags (`NZCV` register).\n    - Floating-point status (`FPSR` register).\n  - RISC-V\n    - Floating-point exception flags in `fcsr` (`fflags`).\n- On x86, the direction flag (DF in `EFLAGS`) is clear on entry to an asm block and must be clear on exit.\n  - Behavior is undefined if the direction flag is set on exiting an asm block.\n- The requirement of restoring the stack pointer and non-output registers to their original value only applies when exiting an `asm!` block.\n  - This means that `asm!` blocks that never return (even if not marked `noreturn`) don't need to preserve these registers.\n  - When returning to a different `asm!` block than you entered (e.g. for context switching), these registers must contain the value they had upon entering the `asm!` block that you are *exiting*.\n    - You cannot exit an `asm!` block that has not been entered. Neither can you exit an `asm!` block that has already been exited.\n    - You are responsible for switching any target-specific state (e.g. thread-local storage, stack bounds).\n    - The set of memory locations that you may access is the intersection of those allowed by the `asm!` blocks you entered and exited.\n- You cannot assume that an `asm!` block will appear exactly once in the output binary. The compiler is allowed to instantiate multiple copies of the `asm!` block, for example when the function containing it is inlined in multiple places.\n  - As a consequence, you should only use [local labels] inside inline assembly code. Defining symbols in assembly code may lead to assembler and/or linker errors due to duplicate symbol definitions.\n\n> **Note**: As a general rule, the flags covered by `preserves_flags` are those which are *not* preserved when performing a function call.\n\n[local labels]: https://sourceware.org/binutils/docs/as/Symbol-Names.html#Local-Labels\n" } , LintCompletion { label : "core_private_diy_float" , description : "# `core_private_diy_float`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "trace_macros" , description : "# `trace_macros`\n\nThe tracking issue for this feature is [#29598].\n\n[#29598]: https://github.com/rust-lang/rust/issues/29598\n\n------------------------\n\nWith `trace_macros` you can trace the expansion of macros in your code.\n\n## Examples\n\n```rust\n#![feature(trace_macros)]\n\nfn main() {\n    trace_macros!(true);\n    println!(\"Hello, Rust!\");\n    trace_macros!(false);\n}\n```\n\nThe `cargo build` output:\n\n```txt\nnote: trace_macro\n --> src/main.rs:5:5\n  |\n5 |     println!(\"Hello, Rust!\");\n  |     ^^^^^^^^^^^^^^^^^^^^^^^^^\n  |\n  = note: expanding `println! { \"Hello, Rust!\" }`\n  = note: to `print ! ( concat ! ( \"Hello, Rust!\" , \"\\n\" ) )`\n  = note: expanding `print! { concat ! ( \"Hello, Rust!\" , \"\\n\" ) }`\n  = note: to `$crate :: io :: _print ( format_args ! ( concat ! ( \"Hello, Rust!\" , \"\\n\" ) )\n          )`\n\n    Finished dev [unoptimized + debuginfo] target(s) in 0.60 secs\n```\n" } , LintCompletion { label : "concat_idents" , description : "# `concat_idents`\n\nThe tracking issue for this feature is: [#29599]\n\n[#29599]: https://github.com/rust-lang/rust/issues/29599\n\n------------------------\n\nThe `concat_idents` feature adds a macro for concatenating multiple identifiers\ninto one identifier.\n\n## Examples\n\n```rust\n#![feature(concat_idents)]\n\nfn main() {\n    fn foobar() -> u32 { 23 }\n    let f = concat_idents!(foo, bar);\n    assert_eq!(f(), 23);\n}\n```" } , LintCompletion { label : "windows_net" , description : "# `windows_net`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "derive_clone_copy" , description : "# `derive_clone_copy`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "libstd_thread_internals" , description : "# `libstd_thread_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "test" , description : "# `test`\n\nThe tracking issue for this feature is: None.\n\n------------------------\n\nThe internals of the `test` crate are unstable, behind the `test` flag.  The\nmost widely used part of the `test` crate are benchmark tests, which can test\nthe performance of your code.  Let's make our `src/lib.rs` look like this\n(comments elided):\n\n```rust,ignore\n#![feature(test)]\n\nextern crate test;\n\npub fn add_two(a: i32) -> i32 {\n    a + 2\n}\n\n#[cfg(test)]\nmod tests {\n    use super::*;\n    use test::Bencher;\n\n    #[test]\n    fn it_works() {\n        assert_eq!(4, add_two(2));\n    }\n\n    #[bench]\n    fn bench_add_two(b: &mut Bencher) {\n        b.iter(|| add_two(2));\n    }\n}\n```\n\nNote the `test` feature gate, which enables this unstable feature.\n\nWe've imported the `test` crate, which contains our benchmarking support.\nWe have a new function as well, with the `bench` attribute. Unlike regular\ntests, which take no arguments, benchmark tests take a `&mut Bencher`. This\n`Bencher` provides an `iter` method, which takes a closure. This closure\ncontains the code we'd like to benchmark.\n\nWe can run benchmark tests with `cargo bench`:\n\n```bash\n$ cargo bench\n   Compiling adder v0.0.1 (file:///home/steve/tmp/adder)\n     Running target/release/adder-91b3e234d4ed382a\n\nrunning 2 tests\ntest tests::it_works ... ignored\ntest tests::bench_add_two ... bench:         1 ns/iter (+/- 0)\n\ntest result: ok. 0 passed; 0 failed; 1 ignored; 1 measured\n```\n\nOur non-benchmark test was ignored. You may have noticed that `cargo bench`\ntakes a bit longer than `cargo test`. This is because Rust runs our benchmark\na number of times, and then takes the average. Because we're doing so little\nwork in this example, we have a `1 ns/iter (+/- 0)`, but this would show\nthe variance if there was one.\n\nAdvice on writing benchmarks:\n\n\n* Move setup code outside the `iter` loop; only put the part you want to measure inside\n* Make the code do \"the same thing\" on each iteration; do not accumulate or change state\n* Make the outer function idempotent too; the benchmark runner is likely to run\n  it many times\n*  Make the inner `iter` loop short and fast so benchmark runs are fast and the\n   calibrator can adjust the run-length at fine resolution\n* Make the code in the `iter` loop do something simple, to assist in pinpointing\n  performance improvements (or regressions)\n\n## Gotcha: optimizations\n\nThere's another tricky part to writing benchmarks: benchmarks compiled with\noptimizations activated can be dramatically changed by the optimizer so that\nthe benchmark is no longer benchmarking what one expects. For example, the\ncompiler might recognize that some calculation has no external effects and\nremove it entirely.\n\n```rust,ignore\n#![feature(test)]\n\nextern crate test;\nuse test::Bencher;\n\n#[bench]\nfn bench_xor_1000_ints(b: &mut Bencher) {\n    b.iter(|| {\n        (0..1000).fold(0, |old, new| old ^ new);\n    });\n}\n```\n\ngives the following results\n\n```text\nrunning 1 test\ntest bench_xor_1000_ints ... bench:         0 ns/iter (+/- 0)\n\ntest result: ok. 0 passed; 0 failed; 0 ignored; 1 measured\n```\n\nThe benchmarking runner offers two ways to avoid this. Either, the closure that\nthe `iter` method receives can return an arbitrary value which forces the\noptimizer to consider the result used and ensures it cannot remove the\ncomputation entirely. This could be done for the example above by adjusting the\n`b.iter` call to\n\n```rust\n# struct X;\n# impl X { fn iter<T, F>(&self, _: F) where F: FnMut() -> T {} } let b = X;\nb.iter(|| {\n    // Note lack of `;` (could also use an explicit `return`).\n    (0..1000).fold(0, |old, new| old ^ new)\n});\n```\n\nOr, the other option is to call the generic `test::black_box` function, which\nis an opaque \"black box\" to the optimizer and so forces it to consider any\nargument as used.\n\n```rust\n#![feature(test)]\n\nextern crate test;\n\n# fn main() {\n# struct X;\n# impl X { fn iter<T, F>(&self, _: F) where F: FnMut() -> T {} } let b = X;\nb.iter(|| {\n    let n = test::black_box(1000);\n\n    (0..n).fold(0, |a, b| a ^ b)\n})\n# }\n```\n\nNeither of these read or modify the value, and are very cheap for small values.\nLarger values can be passed indirectly to reduce overhead (e.g.\n`black_box(&huge_struct)`).\n\nPerforming either of the above changes gives the following benchmarking results\n\n```text\nrunning 1 test\ntest bench_xor_1000_ints ... bench:       131 ns/iter (+/- 3)\n\ntest result: ok. 0 passed; 0 failed; 0 ignored; 1 measured\n```\n\nHowever, the optimizer can still modify a testcase in an undesirable manner\neven when using either of the above.\n" } , LintCompletion { label : "sort_internals" , description : "# `sort_internals`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } , LintCompletion { label : "is_sorted" , description : "# `is_sorted`\n\nThe tracking issue for this feature is: [#53485]\n\n[#53485]: https://github.com/rust-lang/rust/issues/53485\n\n------------------------\n\nAdd the methods `is_sorted`, `is_sorted_by` and `is_sorted_by_key` to `[T]`;\nadd the methods `is_sorted`, `is_sorted_by` and `is_sorted_by_key` to\n`Iterator`.\n" } , LintCompletion { label : "llvm_asm" , description : "# `llvm_asm`\n\nThe tracking issue for this feature is: [#70173]\n\n[#70173]: https://github.com/rust-lang/rust/issues/70173\n\n------------------------\n\nFor extremely low-level manipulations and performance reasons, one\nmight wish to control the CPU directly. Rust supports using inline\nassembly to do this via the `llvm_asm!` macro.\n\n```rust,ignore\nllvm_asm!(assembly template\n   : output operands\n   : input operands\n   : clobbers\n   : options\n   );\n```\n\nAny use of `llvm_asm` is feature gated (requires `#![feature(llvm_asm)]` on the\ncrate to allow) and of course requires an `unsafe` block.\n\n> **Note**: the examples here are given in x86/x86-64 assembly, but\n> all platforms are supported.\n\n## Assembly template\n\nThe `assembly template` is the only required parameter and must be a\nliteral string (i.e. `\"\"`)\n\n```rust\n#![feature(llvm_asm)]\n\n#[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\nfn foo() {\n    unsafe {\n        llvm_asm!(\"NOP\");\n    }\n}\n\n// Other platforms:\n#[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\nfn foo() { /* ... */ }\n\nfn main() {\n    // ...\n    foo();\n    // ...\n}\n```\n\n(The `feature(llvm_asm)` and `#[cfg]`s are omitted from now on.)\n\nOutput operands, input operands, clobbers and options are all optional\nbut you must add the right number of `:` if you skip them:\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n# fn main() { unsafe {\nllvm_asm!(\"xor %eax, %eax\"\n    :\n    :\n    : \"eax\"\n   );\n# } }\n# #[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\n# fn main() {}\n```\n\nWhitespace also doesn't matter:\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n# fn main() { unsafe {\nllvm_asm!(\"xor %eax, %eax\" ::: \"eax\");\n# } }\n# #[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\n# fn main() {}\n```\n\n## Operands\n\nInput and output operands follow the same format: `:\n\"constraints1\"(expr1), \"constraints2\"(expr2), ...\"`. Output operand\nexpressions must be mutable place, or not yet assigned:\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\nfn add(a: i32, b: i32) -> i32 {\n    let c: i32;\n    unsafe {\n        llvm_asm!(\"add $2, $0\"\n             : \"=r\"(c)\n             : \"0\"(a), \"r\"(b)\n             );\n    }\n    c\n}\n# #[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\n# fn add(a: i32, b: i32) -> i32 { a + b }\n\nfn main() {\n    assert_eq!(add(3, 14159), 14162)\n}\n```\n\nIf you would like to use real operands in this position, however,\nyou are required to put curly braces `{}` around the register that\nyou want, and you are required to put the specific size of the\noperand. This is useful for very low level programming, where\nwhich register you use is important:\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n# unsafe fn read_byte_in(port: u16) -> u8 {\nlet result: u8;\nllvm_asm!(\"in %dx, %al\" : \"={al}\"(result) : \"{dx}\"(port));\nresult\n# }\n```\n\n## Clobbers\n\nSome instructions modify registers which might otherwise have held\ndifferent values so we use the clobbers list to indicate to the\ncompiler not to assume any values loaded into those registers will\nstay valid.\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n# fn main() { unsafe {\n// Put the value 0x200 in eax:\nllvm_asm!(\"mov $$0x200, %eax\" : /* no outputs */ : /* no inputs */ : \"eax\");\n# } }\n# #[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\n# fn main() {}\n```\n\nInput and output registers need not be listed since that information\nis already communicated by the given constraints. Otherwise, any other\nregisters used either implicitly or explicitly should be listed.\n\nIf the assembly changes the condition code register `cc` should be\nspecified as one of the clobbers. Similarly, if the assembly modifies\nmemory, `memory` should also be specified.\n\n## Options\n\nThe last section, `options` is specific to Rust. The format is comma\nseparated literal strings (i.e. `:\"foo\", \"bar\", \"baz\"`). It's used to\nspecify some extra info about the inline assembly:\n\nCurrent valid options are:\n\n1. *volatile* - specifying this is analogous to\n   `__asm__ __volatile__ (...)` in gcc/clang.\n2. *alignstack* - certain instructions expect the stack to be\n   aligned a certain way (i.e. SSE) and specifying this indicates to\n   the compiler to insert its usual stack alignment code\n3. *intel* - use intel syntax instead of the default AT&T.\n\n```rust\n# #![feature(llvm_asm)]\n# #[cfg(any(target_arch = \"x86\", target_arch = \"x86_64\"))]\n# fn main() {\nlet result: i32;\nunsafe {\n   llvm_asm!(\"mov eax, 2\" : \"={eax}\"(result) : : : \"intel\")\n}\nprintln!(\"eax is currently {}\", result);\n# }\n# #[cfg(not(any(target_arch = \"x86\", target_arch = \"x86_64\")))]\n# fn main() {}\n```\n\n## More Information\n\nThe current implementation of the `llvm_asm!` macro is a direct binding to [LLVM's\ninline assembler expressions][llvm-docs], so be sure to check out [their\ndocumentation as well][llvm-docs] for more information about clobbers,\nconstraints, etc.\n\n[llvm-docs]: http://llvm.org/docs/LangRef.html#inline-assembler-expressions\n\nIf you need more power and don't mind losing some of the niceties of\n`llvm_asm!`, check out [global_asm](global-asm.md).\n" } , LintCompletion { label : "format_args_capture" , description : "# `format_args_capture`\n\nThe tracking issue for this feature is: [#67984]\n\n[#67984]: https://github.com/rust-lang/rust/issues/67984\n\n------------------------\n\nEnables `format_args!` (and macros which use `format_args!` in their implementation, such\nas `format!`, `print!` and `panic!`) to capture variables from the surrounding scope.\nThis avoids the need to pass named parameters when the binding in question\nalready exists in scope.\n\n```rust\n#![feature(format_args_capture)]\n\nlet (person, species, name) = (\"Charlie Brown\", \"dog\", \"Snoopy\");\n\n// captures named argument `person`\nprint!(\"Hello {person}\");\n\n// captures named arguments `species` and `name`\nformat!(\"The {species}'s name is {name}.\");\n```\n\nThis also works for formatting parameters such as width and precision:\n\n```rust\n#![feature(format_args_capture)]\n\nlet precision = 2;\nlet s = format!(\"{:.precision$}\", 1.324223);\n\nassert_eq!(&s, \"1.32\");\n```\n\nA non-exhaustive list of macros which benefit from this functionality include:\n- `format!`\n- `print!` and `println!`\n- `eprint!` and `eprintln!`\n- `write!` and `writeln!`\n- `panic!`\n- `unreachable!`\n- `unimplemented!`\n- `todo!`\n- `assert!` and similar\n- macros in many thirdparty crates, such as `log`\n" } , LintCompletion { label : "set_stdio" , description : "# `set_stdio`\n\nThis feature is internal to the Rust compiler and is not intended for general use.\n\n------------------------\n" } ] ;
diff --git a/crates/ide/src/completion/patterns.rs b/crates/ide/src/completion/patterns.rs
new file mode 100644
index 000000000..ffc97c076
--- /dev/null
+++ b/crates/ide/src/completion/patterns.rs
@@ -0,0 +1,194 @@
+//! Patterns telling us certain facts about current syntax element, they are used in completion context
+
+use syntax::{
+    algo::non_trivia_sibling,
+    ast::{self, LoopBodyOwner},
+    match_ast, AstNode, Direction, NodeOrToken, SyntaxElement,
+    SyntaxKind::*,
+    SyntaxNode, SyntaxToken,
+};
+
+#[cfg(test)]
+use crate::completion::test_utils::check_pattern_is_applicable;
+
+pub(crate) fn has_trait_parent(element: SyntaxElement) -> bool {
+    not_same_range_ancestor(element)
+        .filter(|it| it.kind() == ASSOC_ITEM_LIST)
+        .and_then(|it| it.parent())
+        .filter(|it| it.kind() == TRAIT)
+        .is_some()
+}
+#[test]
+fn test_has_trait_parent() {
+    check_pattern_is_applicable(r"trait A { f<|> }", has_trait_parent);
+}
+
+pub(crate) fn has_impl_parent(element: SyntaxElement) -> bool {
+    not_same_range_ancestor(element)
+        .filter(|it| it.kind() == ASSOC_ITEM_LIST)
+        .and_then(|it| it.parent())
+        .filter(|it| it.kind() == IMPL)
+        .is_some()
+}
+#[test]
+fn test_has_impl_parent() {
+    check_pattern_is_applicable(r"impl A { f<|> }", has_impl_parent);
+}
+
+pub(crate) fn has_block_expr_parent(element: SyntaxElement) -> bool {
+    not_same_range_ancestor(element).filter(|it| it.kind() == BLOCK_EXPR).is_some()
+}
+#[test]
+fn test_has_block_expr_parent() {
+    check_pattern_is_applicable(r"fn my_fn() { let a = 2; f<|> }", has_block_expr_parent);
+}
+
+pub(crate) fn has_bind_pat_parent(element: SyntaxElement) -> bool {
+    element.ancestors().find(|it| it.kind() == IDENT_PAT).is_some()
+}
+#[test]
+fn test_has_bind_pat_parent() {
+    check_pattern_is_applicable(r"fn my_fn(m<|>) {}", has_bind_pat_parent);
+    check_pattern_is_applicable(r"fn my_fn() { let m<|> }", has_bind_pat_parent);
+}
+
+pub(crate) fn has_ref_parent(element: SyntaxElement) -> bool {
+    not_same_range_ancestor(element)
+        .filter(|it| it.kind() == REF_PAT || it.kind() == REF_EXPR)
+        .is_some()
+}
+#[test]
+fn test_has_ref_parent() {
+    check_pattern_is_applicable(r"fn my_fn(&m<|>) {}", has_ref_parent);
+    check_pattern_is_applicable(r"fn my() { let &m<|> }", has_ref_parent);
+}
+
+pub(crate) fn has_item_list_or_source_file_parent(element: SyntaxElement) -> bool {
+    let ancestor = not_same_range_ancestor(element);
+    if !ancestor.is_some() {
+        return true;
+    }
+    ancestor.filter(|it| it.kind() == SOURCE_FILE || it.kind() == ITEM_LIST).is_some()
+}
+#[test]
+fn test_has_item_list_or_source_file_parent() {
+    check_pattern_is_applicable(r"i<|>", has_item_list_or_source_file_parent);
+    check_pattern_is_applicable(r"mod foo { f<|> }", has_item_list_or_source_file_parent);
+}
+
+pub(crate) fn is_match_arm(element: SyntaxElement) -> bool {
+    not_same_range_ancestor(element.clone()).filter(|it| it.kind() == MATCH_ARM).is_some()
+        && previous_sibling_or_ancestor_sibling(element)
+            .and_then(|it| it.into_token())
+            .filter(|it| it.kind() == FAT_ARROW)
+            .is_some()
+}
+#[test]
+fn test_is_match_arm() {
+    check_pattern_is_applicable(r"fn my_fn() { match () { () => m<|> } }", is_match_arm);
+}
+
+pub(crate) fn unsafe_is_prev(element: SyntaxElement) -> bool {
+    element
+        .into_token()
+        .and_then(|it| previous_non_trivia_token(it))
+        .filter(|it| it.kind() == UNSAFE_KW)
+        .is_some()
+}
+#[test]
+fn test_unsafe_is_prev() {
+    check_pattern_is_applicable(r"unsafe i<|>", unsafe_is_prev);
+}
+
+pub(crate) fn if_is_prev(element: SyntaxElement) -> bool {
+    element
+        .into_token()
+        .and_then(|it| previous_non_trivia_token(it))
+        .filter(|it| it.kind() == IF_KW)
+        .is_some()
+}
+#[test]
+fn test_if_is_prev() {
+    check_pattern_is_applicable(r"if l<|>", if_is_prev);
+}
+
+pub(crate) fn has_trait_as_prev_sibling(element: SyntaxElement) -> bool {
+    previous_sibling_or_ancestor_sibling(element).filter(|it| it.kind() == TRAIT).is_some()
+}
+#[test]
+fn test_has_trait_as_prev_sibling() {
+    check_pattern_is_applicable(r"trait A w<|> {}", has_trait_as_prev_sibling);
+}
+
+pub(crate) fn has_impl_as_prev_sibling(element: SyntaxElement) -> bool {
+    previous_sibling_or_ancestor_sibling(element).filter(|it| it.kind() == IMPL).is_some()
+}
+#[test]
+fn test_has_impl_as_prev_sibling() {
+    check_pattern_is_applicable(r"impl A w<|> {}", has_impl_as_prev_sibling);
+}
+
+pub(crate) fn is_in_loop_body(element: SyntaxElement) -> bool {
+    let leaf = match element {
+        NodeOrToken::Node(node) => node,
+        NodeOrToken::Token(token) => token.parent(),
+    };
+    for node in leaf.ancestors() {
+        if node.kind() == FN || node.kind() == CLOSURE_EXPR {
+            break;
+        }
+        let loop_body = match_ast! {
+            match node {
+                ast::ForExpr(it) => it.loop_body(),
+                ast::WhileExpr(it) => it.loop_body(),
+                ast::LoopExpr(it) => it.loop_body(),
+                _ => None,
+            }
+        };
+        if let Some(body) = loop_body {
+            if body.syntax().text_range().contains_range(leaf.text_range()) {
+                return true;
+            }
+        }
+    }
+    false
+}
+
+fn not_same_range_ancestor(element: SyntaxElement) -> Option<SyntaxNode> {
+    element
+        .ancestors()
+        .take_while(|it| it.text_range() == element.text_range())
+        .last()
+        .and_then(|it| it.parent())
+}
+
+fn previous_non_trivia_token(token: SyntaxToken) -> Option<SyntaxToken> {
+    let mut token = token.prev_token();
+    while let Some(inner) = token.clone() {
+        if !inner.kind().is_trivia() {
+            return Some(inner);
+        } else {
+            token = inner.prev_token();
+        }
+    }
+    None
+}
+
+fn previous_sibling_or_ancestor_sibling(element: SyntaxElement) -> Option<SyntaxElement> {
+    let token_sibling = non_trivia_sibling(element.clone(), Direction::Prev);
+    if let Some(sibling) = token_sibling {
+        Some(sibling)
+    } else {
+        // if not trying to find first ancestor which has such a sibling
+        let node = match element {
+            NodeOrToken::Node(node) => node,
+            NodeOrToken::Token(token) => token.parent(),
+        };
+        let range = node.text_range();
+        let top_node = node.ancestors().take_while(|it| it.text_range() == range).last()?;
+        let prev_sibling_node = top_node.ancestors().find(|it| {
+            non_trivia_sibling(NodeOrToken::Node(it.to_owned()), Direction::Prev).is_some()
+        })?;
+        non_trivia_sibling(NodeOrToken::Node(prev_sibling_node), Direction::Prev)
+    }
+}
diff --git a/crates/ide/src/completion/presentation.rs b/crates/ide/src/completion/presentation.rs
new file mode 100644
index 000000000..3371aed2d
--- /dev/null
+++ b/crates/ide/src/completion/presentation.rs
@@ -0,0 +1,1227 @@
+//! This modules takes care of rendering various definitions as completion items.
+//! It also handles scoring (sorting) completions.
+
+use hir::{Docs, HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
+use itertools::Itertools;
+use syntax::ast::NameOwner;
+use test_utils::mark;
+
+use crate::{
+    completion::{
+        completion_item::Builder, CompletionContext, CompletionItem, CompletionItemKind,
+        CompletionKind, Completions,
+    },
+    display::{const_label, function_declaration, macro_label, type_label},
+    CompletionScore, RootDatabase,
+};
+
+impl Completions {
+    pub(crate) fn add_field(&mut self, ctx: &CompletionContext, field: hir::Field, ty: &Type) {
+        let is_deprecated = is_deprecated(field, ctx.db);
+        let name = field.name(ctx.db);
+        let mut completion_item =
+            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.to_string())
+                .kind(CompletionItemKind::Field)
+                .detail(ty.display(ctx.db).to_string())
+                .set_documentation(field.docs(ctx.db))
+                .set_deprecated(is_deprecated);
+
+        if let Some(score) = compute_score(ctx, &ty, &name.to_string()) {
+            completion_item = completion_item.set_score(score);
+        }
+
+        completion_item.add_to(self);
+    }
+
+    pub(crate) fn add_tuple_field(&mut self, ctx: &CompletionContext, field: usize, ty: &Type) {
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), field.to_string())
+            .kind(CompletionItemKind::Field)
+            .detail(ty.display(ctx.db).to_string())
+            .add_to(self);
+    }
+
+    pub(crate) fn add_resolution(
+        &mut self,
+        ctx: &CompletionContext,
+        local_name: String,
+        resolution: &ScopeDef,
+    ) {
+        use hir::ModuleDef::*;
+
+        let completion_kind = match resolution {
+            ScopeDef::ModuleDef(BuiltinType(..)) => CompletionKind::BuiltinType,
+            _ => CompletionKind::Reference,
+        };
+
+        let kind = match resolution {
+            ScopeDef::ModuleDef(Module(..)) => CompletionItemKind::Module,
+            ScopeDef::ModuleDef(Function(func)) => {
+                return self.add_function(ctx, *func, Some(local_name));
+            }
+            ScopeDef::ModuleDef(Adt(hir::Adt::Struct(_))) => CompletionItemKind::Struct,
+            // FIXME: add CompletionItemKind::Union
+            ScopeDef::ModuleDef(Adt(hir::Adt::Union(_))) => CompletionItemKind::Struct,
+            ScopeDef::ModuleDef(Adt(hir::Adt::Enum(_))) => CompletionItemKind::Enum,
+
+            ScopeDef::ModuleDef(EnumVariant(var)) => {
+                return self.add_enum_variant(ctx, *var, Some(local_name));
+            }
+            ScopeDef::ModuleDef(Const(..)) => CompletionItemKind::Const,
+            ScopeDef::ModuleDef(Static(..)) => CompletionItemKind::Static,
+            ScopeDef::ModuleDef(Trait(..)) => CompletionItemKind::Trait,
+            ScopeDef::ModuleDef(TypeAlias(..)) => CompletionItemKind::TypeAlias,
+            ScopeDef::ModuleDef(BuiltinType(..)) => CompletionItemKind::BuiltinType,
+            ScopeDef::GenericParam(..) => CompletionItemKind::TypeParam,
+            ScopeDef::Local(..) => CompletionItemKind::Binding,
+            // (does this need its own kind?)
+            ScopeDef::AdtSelfType(..) | ScopeDef::ImplSelfType(..) => CompletionItemKind::TypeParam,
+            ScopeDef::MacroDef(mac) => {
+                return self.add_macro(ctx, Some(local_name), *mac);
+            }
+            ScopeDef::Unknown => {
+                return self.add(
+                    CompletionItem::new(CompletionKind::Reference, ctx.source_range(), local_name)
+                        .kind(CompletionItemKind::UnresolvedReference),
+                );
+            }
+        };
+
+        let docs = match resolution {
+            ScopeDef::ModuleDef(Module(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Adt(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(EnumVariant(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Const(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Static(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Trait(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(TypeAlias(it)) => it.docs(ctx.db),
+            _ => None,
+        };
+
+        let mut completion_item =
+            CompletionItem::new(completion_kind, ctx.source_range(), local_name.clone());
+        if let ScopeDef::Local(local) = resolution {
+            let ty = local.ty(ctx.db);
+            if !ty.is_unknown() {
+                completion_item = completion_item.detail(ty.display(ctx.db).to_string());
+            }
+        };
+
+        if let ScopeDef::Local(local) = resolution {
+            if let Some(score) = compute_score(ctx, &local.ty(ctx.db), &local_name) {
+                completion_item = completion_item.set_score(score);
+            }
+        }
+
+        // Add `<>` for generic types
+        if ctx.is_path_type && !ctx.has_type_args && ctx.config.add_call_parenthesis {
+            if let Some(cap) = ctx.config.snippet_cap {
+                let has_non_default_type_params = match resolution {
+                    ScopeDef::ModuleDef(Adt(it)) => it.has_non_default_type_params(ctx.db),
+                    ScopeDef::ModuleDef(TypeAlias(it)) => it.has_non_default_type_params(ctx.db),
+                    _ => false,
+                };
+                if has_non_default_type_params {
+                    mark::hit!(inserts_angle_brackets_for_generics);
+                    completion_item = completion_item
+                        .lookup_by(local_name.clone())
+                        .label(format!("{}<…>", local_name))
+                        .insert_snippet(cap, format!("{}<$0>", local_name));
+                }
+            }
+        }
+
+        completion_item.kind(kind).set_documentation(docs).add_to(self)
+    }
+
+    pub(crate) fn add_macro(
+        &mut self,
+        ctx: &CompletionContext,
+        name: Option<String>,
+        macro_: hir::MacroDef,
+    ) {
+        // FIXME: Currently proc-macro do not have ast-node,
+        // such that it does not have source
+        if macro_.is_proc_macro() {
+            return;
+        }
+
+        let name = match name {
+            Some(it) => it,
+            None => return,
+        };
+
+        let ast_node = macro_.source(ctx.db).value;
+        let detail = macro_label(&ast_node);
+
+        let docs = macro_.docs(ctx.db);
+
+        let mut builder = CompletionItem::new(
+            CompletionKind::Reference,
+            ctx.source_range(),
+            &format!("{}!", name),
+        )
+        .kind(CompletionItemKind::Macro)
+        .set_documentation(docs.clone())
+        .set_deprecated(is_deprecated(macro_, ctx.db))
+        .detail(detail);
+
+        let needs_bang = ctx.use_item_syntax.is_none() && !ctx.is_macro_call;
+        builder = match ctx.config.snippet_cap {
+            Some(cap) if needs_bang => {
+                let docs = docs.as_ref().map_or("", |s| s.as_str());
+                let (bra, ket) = guess_macro_braces(&name, docs);
+                builder
+                    .insert_snippet(cap, format!("{}!{}$0{}", name, bra, ket))
+                    .label(format!("{}!{}…{}", name, bra, ket))
+                    .lookup_by(format!("{}!", name))
+            }
+            None if needs_bang => builder.insert_text(format!("{}!", name)),
+            _ => {
+                mark::hit!(dont_insert_macro_call_parens_unncessary);
+                builder.insert_text(name)
+            }
+        };
+
+        self.add(builder);
+    }
+
+    pub(crate) fn add_function(
+        &mut self,
+        ctx: &CompletionContext,
+        func: hir::Function,
+        local_name: Option<String>,
+    ) {
+        let name = local_name.unwrap_or_else(|| func.name(ctx.db).to_string());
+        let ast_node = func.source(ctx.db).value;
+
+        let mut builder =
+            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.clone())
+                .kind(if func.self_param(ctx.db).is_some() {
+                    CompletionItemKind::Method
+                } else {
+                    CompletionItemKind::Function
+                })
+                .set_documentation(func.docs(ctx.db))
+                .set_deprecated(is_deprecated(func, ctx.db))
+                .detail(function_declaration(&ast_node));
+
+        let params = ast_node
+            .param_list()
+            .into_iter()
+            .flat_map(|it| it.params())
+            .flat_map(|it| it.pat())
+            .map(|pat| pat.to_string().trim_start_matches('_').into())
+            .collect();
+
+        builder = builder.add_call_parens(ctx, name, Params::Named(params));
+
+        self.add(builder)
+    }
+
+    pub(crate) fn add_const(&mut self, ctx: &CompletionContext, constant: hir::Const) {
+        let ast_node = constant.source(ctx.db).value;
+        let name = match ast_node.name() {
+            Some(name) => name,
+            _ => return,
+        };
+        let detail = const_label(&ast_node);
+
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.text().to_string())
+            .kind(CompletionItemKind::Const)
+            .set_documentation(constant.docs(ctx.db))
+            .set_deprecated(is_deprecated(constant, ctx.db))
+            .detail(detail)
+            .add_to(self);
+    }
+
+    pub(crate) fn add_type_alias(&mut self, ctx: &CompletionContext, type_alias: hir::TypeAlias) {
+        let type_def = type_alias.source(ctx.db).value;
+        let name = match type_def.name() {
+            Some(name) => name,
+            _ => return,
+        };
+        let detail = type_label(&type_def);
+
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.text().to_string())
+            .kind(CompletionItemKind::TypeAlias)
+            .set_documentation(type_alias.docs(ctx.db))
+            .set_deprecated(is_deprecated(type_alias, ctx.db))
+            .detail(detail)
+            .add_to(self);
+    }
+
+    pub(crate) fn add_qualified_enum_variant(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        path: ModPath,
+    ) {
+        self.add_enum_variant_impl(ctx, variant, None, Some(path))
+    }
+
+    pub(crate) fn add_enum_variant(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        local_name: Option<String>,
+    ) {
+        self.add_enum_variant_impl(ctx, variant, local_name, None)
+    }
+
+    fn add_enum_variant_impl(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        local_name: Option<String>,
+        path: Option<ModPath>,
+    ) {
+        let is_deprecated = is_deprecated(variant, ctx.db);
+        let name = local_name.unwrap_or_else(|| variant.name(ctx.db).to_string());
+        let qualified_name = match &path {
+            Some(it) => it.to_string(),
+            None => name.to_string(),
+        };
+        let detail_types = variant
+            .fields(ctx.db)
+            .into_iter()
+            .map(|field| (field.name(ctx.db), field.signature_ty(ctx.db)));
+        let variant_kind = variant.kind(ctx.db);
+        let detail = match variant_kind {
+            StructKind::Tuple | StructKind::Unit => format!(
+                "({})",
+                detail_types.map(|(_, t)| t.display(ctx.db).to_string()).format(", ")
+            ),
+            StructKind::Record => format!(
+                "{{ {} }}",
+                detail_types
+                    .map(|(n, t)| format!("{}: {}", n, t.display(ctx.db).to_string()))
+                    .format(", ")
+            ),
+        };
+        let mut res = CompletionItem::new(
+            CompletionKind::Reference,
+            ctx.source_range(),
+            qualified_name.clone(),
+        )
+        .kind(CompletionItemKind::EnumVariant)
+        .set_documentation(variant.docs(ctx.db))
+        .set_deprecated(is_deprecated)
+        .detail(detail);
+
+        if path.is_some() {
+            res = res.lookup_by(name);
+        }
+
+        if variant_kind == StructKind::Tuple {
+            mark::hit!(inserts_parens_for_tuple_enums);
+            let params = Params::Anonymous(variant.fields(ctx.db).len());
+            res = res.add_call_parens(ctx, qualified_name, params)
+        }
+
+        res.add_to(self);
+    }
+}
+
+pub(crate) fn compute_score(
+    ctx: &CompletionContext,
+    ty: &Type,
+    name: &str,
+) -> Option<CompletionScore> {
+    let (active_name, active_type) = if let Some(record_field) = &ctx.record_field_syntax {
+        mark::hit!(record_field_type_match);
+        let (struct_field, _local) = ctx.sema.resolve_record_field(record_field)?;
+        (struct_field.name(ctx.db).to_string(), struct_field.signature_ty(ctx.db))
+    } else if let Some(active_parameter) = &ctx.active_parameter {
+        mark::hit!(active_param_type_match);
+        (active_parameter.name.clone(), active_parameter.ty.clone())
+    } else {
+        return None;
+    };
+
+    // Compute score
+    // For the same type
+    if &active_type != ty {
+        return None;
+    }
+
+    let mut res = CompletionScore::TypeMatch;
+
+    // If same type + same name then go top position
+    if active_name == name {
+        res = CompletionScore::TypeAndNameMatch
+    }
+
+    Some(res)
+}
+
+enum Params {
+    Named(Vec<String>),
+    Anonymous(usize),
+}
+
+impl Params {
+    fn len(&self) -> usize {
+        match self {
+            Params::Named(xs) => xs.len(),
+            Params::Anonymous(len) => *len,
+        }
+    }
+
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+}
+
+impl Builder {
+    fn add_call_parens(mut self, ctx: &CompletionContext, name: String, params: Params) -> Builder {
+        if !ctx.config.add_call_parenthesis {
+            return self;
+        }
+        if ctx.use_item_syntax.is_some() {
+            mark::hit!(no_parens_in_use_item);
+            return self;
+        }
+        if ctx.is_pattern_call {
+            mark::hit!(dont_duplicate_pattern_parens);
+            return self;
+        }
+        if ctx.is_call {
+            return self;
+        }
+
+        // Don't add parentheses if the expected type is some function reference.
+        if let Some(ty) = &ctx.expected_type {
+            if ty.is_fn() {
+                mark::hit!(no_call_parens_if_fn_ptr_needed);
+                return self;
+            }
+        }
+
+        let cap = match ctx.config.snippet_cap {
+            Some(it) => it,
+            None => return self,
+        };
+        // If not an import, add parenthesis automatically.
+        mark::hit!(inserts_parens_for_function_calls);
+
+        let (snippet, label) = if params.is_empty() {
+            (format!("{}()$0", name), format!("{}()", name))
+        } else {
+            self = self.trigger_call_info();
+            let snippet = match (ctx.config.add_call_argument_snippets, params) {
+                (true, Params::Named(params)) => {
+                    let function_params_snippet =
+                        params.iter().enumerate().format_with(", ", |(index, param_name), f| {
+                            f(&format_args!("${{{}:{}}}", index + 1, param_name))
+                        });
+                    format!("{}({})$0", name, function_params_snippet)
+                }
+                _ => {
+                    mark::hit!(suppress_arg_snippets);
+                    format!("{}($0)", name)
+                }
+            };
+
+            (snippet, format!("{}(…)", name))
+        };
+        self.lookup_by(name).label(label).insert_snippet(cap, snippet)
+    }
+}
+
+fn is_deprecated(node: impl HasAttrs, db: &RootDatabase) -> bool {
+    node.attrs(db).by_key("deprecated").exists()
+}
+
+fn guess_macro_braces(macro_name: &str, docs: &str) -> (&'static str, &'static str) {
+    let mut votes = [0, 0, 0];
+    for (idx, s) in docs.match_indices(&macro_name) {
+        let (before, after) = (&docs[..idx], &docs[idx + s.len()..]);
+        // Ensure to match the full word
+        if after.starts_with('!')
+            && !before.ends_with(|c: char| c == '_' || c.is_ascii_alphanumeric())
+        {
+            // It may have spaces before the braces like `foo! {}`
+            match after[1..].chars().find(|&c| !c.is_whitespace()) {
+                Some('{') => votes[0] += 1,
+                Some('[') => votes[1] += 1,
+                Some('(') => votes[2] += 1,
+                _ => {}
+            }
+        }
+    }
+
+    // Insert a space before `{}`.
+    // We prefer the last one when some votes equal.
+    let (_vote, (bra, ket)) = votes
+        .iter()
+        .zip(&[(" {", "}"), ("[", "]"), ("(", ")")])
+        .max_by_key(|&(&vote, _)| vote)
+        .unwrap();
+    (*bra, *ket)
+}
+
+#[cfg(test)]
+mod tests {
+    use std::cmp::Reverse;
+
+    use expect_test::{expect, Expect};
+    use test_utils::mark;
+
+    use crate::{
+        completion::{
+            test_utils::{
+                check_edit, check_edit_with_config, do_completion, get_all_completion_items,
+            },
+            CompletionConfig, CompletionKind,
+        },
+        CompletionScore,
+    };
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let actual = do_completion(ra_fixture, CompletionKind::Reference);
+        expect.assert_debug_eq(&actual);
+    }
+
+    fn check_scores(ra_fixture: &str, expect: Expect) {
+        fn display_score(score: Option<CompletionScore>) -> &'static str {
+            match score {
+                Some(CompletionScore::TypeMatch) => "[type]",
+                Some(CompletionScore::TypeAndNameMatch) => "[type+name]",
+                None => "[]".into(),
+            }
+        }
+
+        let mut completions = get_all_completion_items(CompletionConfig::default(), ra_fixture);
+        completions.sort_by_key(|it| (Reverse(it.score()), it.label().to_string()));
+        let actual = completions
+            .into_iter()
+            .filter(|it| it.completion_kind == CompletionKind::Reference)
+            .map(|it| {
+                let tag = it.kind().unwrap().tag();
+                let score = display_score(it.score());
+                format!("{} {} {}\n", tag, it.label(), score)
+            })
+            .collect::<String>();
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn enum_detail_includes_record_fields() {
+        check(
+            r#"
+enum Foo { Foo { x: i32, y: i32 } }
+
+fn main() { Foo::Fo<|> }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "Foo",
+                        source_range: 54..56,
+                        delete: 54..56,
+                        insert: "Foo",
+                        kind: EnumVariant,
+                        detail: "{ x: i32, y: i32 }",
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn enum_detail_doesnt_include_tuple_fields() {
+        check(
+            r#"
+enum Foo { Foo (i32, i32) }
+
+fn main() { Foo::Fo<|> }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "Foo(…)",
+                        source_range: 46..48,
+                        delete: 46..48,
+                        insert: "Foo($0)",
+                        kind: EnumVariant,
+                        lookup: "Foo",
+                        detail: "(i32, i32)",
+                        trigger_call_info: true,
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn enum_detail_just_parentheses_for_unit() {
+        check(
+            r#"
+enum Foo { Foo }
+
+fn main() { Foo::Fo<|> }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "Foo",
+                        source_range: 35..37,
+                        delete: 35..37,
+                        insert: "Foo",
+                        kind: EnumVariant,
+                        detail: "()",
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn sets_deprecated_flag_in_completion_items() {
+        check(
+            r#"
+#[deprecated]
+fn something_deprecated() {}
+#[deprecated(since = "1.0.0")]
+fn something_else_deprecated() {}
+
+fn main() { som<|> }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "main()",
+                        source_range: 121..124,
+                        delete: 121..124,
+                        insert: "main()$0",
+                        kind: Function,
+                        lookup: "main",
+                        detail: "fn main()",
+                    },
+                    CompletionItem {
+                        label: "something_deprecated()",
+                        source_range: 121..124,
+                        delete: 121..124,
+                        insert: "something_deprecated()$0",
+                        kind: Function,
+                        lookup: "something_deprecated",
+                        detail: "fn something_deprecated()",
+                        deprecated: true,
+                    },
+                    CompletionItem {
+                        label: "something_else_deprecated()",
+                        source_range: 121..124,
+                        delete: 121..124,
+                        insert: "something_else_deprecated()$0",
+                        kind: Function,
+                        lookup: "something_else_deprecated",
+                        detail: "fn something_else_deprecated()",
+                        deprecated: true,
+                    },
+                ]
+            "#]],
+        );
+
+        check(
+            r#"
+struct A { #[deprecated] the_field: u32 }
+fn foo() { A { the<|> } }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "the_field",
+                        source_range: 57..60,
+                        delete: 57..60,
+                        insert: "the_field",
+                        kind: Field,
+                        detail: "u32",
+                        deprecated: true,
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn renders_docs() {
+        check(
+            r#"
+struct S {
+    /// Field docs
+    foo:
+}
+impl S {
+    /// Method docs
+    fn bar(self) { self.<|> }
+}"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "bar()",
+                        source_range: 94..94,
+                        delete: 94..94,
+                        insert: "bar()$0",
+                        kind: Method,
+                        lookup: "bar",
+                        detail: "fn bar(self)",
+                        documentation: Documentation(
+                            "Method docs",
+                        ),
+                    },
+                    CompletionItem {
+                        label: "foo",
+                        source_range: 94..94,
+                        delete: 94..94,
+                        insert: "foo",
+                        kind: Field,
+                        detail: "{unknown}",
+                        documentation: Documentation(
+                            "Field docs",
+                        ),
+                    },
+                ]
+            "#]],
+        );
+
+        check(
+            r#"
+use self::my<|>;
+
+/// mod docs
+mod my { }
+
+/// enum docs
+enum E {
+    /// variant docs
+    V
+}
+use self::E::*;
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "E",
+                        source_range: 10..12,
+                        delete: 10..12,
+                        insert: "E",
+                        kind: Enum,
+                        documentation: Documentation(
+                            "enum docs",
+                        ),
+                    },
+                    CompletionItem {
+                        label: "V",
+                        source_range: 10..12,
+                        delete: 10..12,
+                        insert: "V",
+                        kind: EnumVariant,
+                        detail: "()",
+                        documentation: Documentation(
+                            "variant docs",
+                        ),
+                    },
+                    CompletionItem {
+                        label: "my",
+                        source_range: 10..12,
+                        delete: 10..12,
+                        insert: "my",
+                        kind: Module,
+                        documentation: Documentation(
+                            "mod docs",
+                        ),
+                    },
+                ]
+            "#]],
+        )
+    }
+
+    #[test]
+    fn dont_render_attrs() {
+        check(
+            r#"
+struct S;
+impl S {
+    #[inline]
+    fn the_method(&self) { }
+}
+fn foo(s: S) { s.<|> }
+"#,
+            expect![[r#"
+                [
+                    CompletionItem {
+                        label: "the_method()",
+                        source_range: 81..81,
+                        delete: 81..81,
+                        insert: "the_method()$0",
+                        kind: Method,
+                        lookup: "the_method",
+                        detail: "fn the_method(&self)",
+                    },
+                ]
+            "#]],
+        )
+    }
+
+    #[test]
+    fn inserts_parens_for_function_calls() {
+        mark::check!(inserts_parens_for_function_calls);
+        check_edit(
+            "no_args",
+            r#"
+fn no_args() {}
+fn main() { no_<|> }
+"#,
+            r#"
+fn no_args() {}
+fn main() { no_args()$0 }
+"#,
+        );
+
+        check_edit(
+            "with_args",
+            r#"
+fn with_args(x: i32, y: String) {}
+fn main() { with_<|> }
+"#,
+            r#"
+fn with_args(x: i32, y: String) {}
+fn main() { with_args(${1:x}, ${2:y})$0 }
+"#,
+        );
+
+        check_edit(
+            "foo",
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn bar(s: &S) { s.f<|> }
+"#,
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn bar(s: &S) { s.foo()$0 }
+"#,
+        );
+
+        check_edit(
+            "foo",
+            r#"
+struct S {}
+impl S {
+    fn foo(&self, x: i32) {}
+}
+fn bar(s: &S) {
+    s.f<|>
+}
+"#,
+            r#"
+struct S {}
+impl S {
+    fn foo(&self, x: i32) {}
+}
+fn bar(s: &S) {
+    s.foo(${1:x})$0
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn suppress_arg_snippets() {
+        mark::check!(suppress_arg_snippets);
+        check_edit_with_config(
+            CompletionConfig { add_call_argument_snippets: false, ..CompletionConfig::default() },
+            "with_args",
+            r#"
+fn with_args(x: i32, y: String) {}
+fn main() { with_<|> }
+"#,
+            r#"
+fn with_args(x: i32, y: String) {}
+fn main() { with_args($0) }
+"#,
+        );
+    }
+
+    #[test]
+    fn strips_underscores_from_args() {
+        check_edit(
+            "foo",
+            r#"
+fn foo(_foo: i32, ___bar: bool, ho_ge_: String) {}
+fn main() { f<|> }
+"#,
+            r#"
+fn foo(_foo: i32, ___bar: bool, ho_ge_: String) {}
+fn main() { foo(${1:foo}, ${2:bar}, ${3:ho_ge_})$0 }
+"#,
+        );
+    }
+
+    #[test]
+    fn inserts_parens_for_tuple_enums() {
+        mark::check!(inserts_parens_for_tuple_enums);
+        check_edit(
+            "Some",
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+fn main() -> Option<i32> {
+    Som<|>
+}
+"#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+fn main() -> Option<i32> {
+    Some($0)
+}
+"#,
+        );
+        check_edit(
+            "Some",
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+fn main(value: Option<i32>) {
+    match value {
+        Som<|>
+    }
+}
+"#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+fn main(value: Option<i32>) {
+    match value {
+        Some($0)
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn dont_duplicate_pattern_parens() {
+        mark::check!(dont_duplicate_pattern_parens);
+        check_edit(
+            "Var",
+            r#"
+enum E { Var(i32) }
+fn main() {
+    match E::Var(92) {
+        E::<|>(92) => (),
+    }
+}
+"#,
+            r#"
+enum E { Var(i32) }
+fn main() {
+    match E::Var(92) {
+        E::Var(92) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_call_parens_if_fn_ptr_needed() {
+        mark::check!(no_call_parens_if_fn_ptr_needed);
+        check_edit(
+            "foo",
+            r#"
+fn foo(foo: u8, bar: u8) {}
+struct ManualVtable { f: fn(u8, u8) }
+
+fn main() -> ManualVtable {
+    ManualVtable { f: f<|> }
+}
+"#,
+            r#"
+fn foo(foo: u8, bar: u8) {}
+struct ManualVtable { f: fn(u8, u8) }
+
+fn main() -> ManualVtable {
+    ManualVtable { f: foo }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_parens_in_use_item() {
+        mark::check!(no_parens_in_use_item);
+        check_edit(
+            "foo",
+            r#"
+mod m { pub fn foo() {} }
+use crate::m::f<|>;
+"#,
+            r#"
+mod m { pub fn foo() {} }
+use crate::m::foo;
+"#,
+        );
+    }
+
+    #[test]
+    fn no_parens_in_call() {
+        check_edit(
+            "foo",
+            r#"
+fn foo(x: i32) {}
+fn main() { f<|>(); }
+"#,
+            r#"
+fn foo(x: i32) {}
+fn main() { foo(); }
+"#,
+        );
+        check_edit(
+            "foo",
+            r#"
+struct Foo;
+impl Foo { fn foo(&self){} }
+fn f(foo: &Foo) { foo.f<|>(); }
+"#,
+            r#"
+struct Foo;
+impl Foo { fn foo(&self){} }
+fn f(foo: &Foo) { foo.foo(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn inserts_angle_brackets_for_generics() {
+        mark::check!(inserts_angle_brackets_for_generics);
+        check_edit(
+            "Vec",
+            r#"
+struct Vec<T> {}
+fn foo(xs: Ve<|>)
+"#,
+            r#"
+struct Vec<T> {}
+fn foo(xs: Vec<$0>)
+"#,
+        );
+        check_edit(
+            "Vec",
+            r#"
+type Vec<T> = (T,);
+fn foo(xs: Ve<|>)
+"#,
+            r#"
+type Vec<T> = (T,);
+fn foo(xs: Vec<$0>)
+"#,
+        );
+        check_edit(
+            "Vec",
+            r#"
+struct Vec<T = i128> {}
+fn foo(xs: Ve<|>)
+"#,
+            r#"
+struct Vec<T = i128> {}
+fn foo(xs: Vec)
+"#,
+        );
+        check_edit(
+            "Vec",
+            r#"
+struct Vec<T> {}
+fn foo(xs: Ve<|><i128>)
+"#,
+            r#"
+struct Vec<T> {}
+fn foo(xs: Vec<i128>)
+"#,
+        );
+    }
+
+    #[test]
+    fn dont_insert_macro_call_parens_unncessary() {
+        mark::check!(dont_insert_macro_call_parens_unncessary);
+        check_edit(
+            "frobnicate!",
+            r#"
+//- /main.rs
+use foo::<|>;
+//- /foo/lib.rs
+#[macro_export]
+macro_rules frobnicate { () => () }
+"#,
+            r#"
+use foo::frobnicate;
+"#,
+        );
+
+        check_edit(
+            "frobnicate!",
+            r#"
+macro_rules frobnicate { () => () }
+fn main() { frob<|>!(); }
+"#,
+            r#"
+macro_rules frobnicate { () => () }
+fn main() { frobnicate!(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn active_param_score() {
+        mark::check!(active_param_type_match);
+        check_scores(
+            r#"
+struct S { foo: i64, bar: u32, baz: u32 }
+fn test(bar: u32) { }
+fn foo(s: S) { test(s.<|>) }
+"#,
+            expect![[r#"
+                fd bar [type+name]
+                fd baz [type]
+                fd foo []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn record_field_scores() {
+        mark::check!(record_field_type_match);
+        check_scores(
+            r#"
+struct A { foo: i64, bar: u32, baz: u32 }
+struct B { x: (), y: f32, bar: u32 }
+fn foo(a: A) { B { bar: a.<|> }; }
+"#,
+            expect![[r#"
+                fd bar [type+name]
+                fd baz [type]
+                fd foo []
+            "#]],
+        )
+    }
+
+    #[test]
+    fn record_field_and_call_scores() {
+        check_scores(
+            r#"
+struct A { foo: i64, bar: u32, baz: u32 }
+struct B { x: (), y: f32, bar: u32 }
+fn f(foo: i64) {  }
+fn foo(a: A) { B { bar: f(a.<|>) }; }
+"#,
+            expect![[r#"
+                fd foo [type+name]
+                fd bar []
+                fd baz []
+            "#]],
+        );
+        check_scores(
+            r#"
+struct A { foo: i64, bar: u32, baz: u32 }
+struct B { x: (), y: f32, bar: u32 }
+fn f(foo: i64) {  }
+fn foo(a: A) { f(B { bar: a.<|> }); }
+"#,
+            expect![[r#"
+                fd bar [type+name]
+                fd baz [type]
+                fd foo []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn prioritize_exact_ref_match() {
+        check_scores(
+            r#"
+struct WorldSnapshot { _f: () };
+fn go(world: &WorldSnapshot) { go(w<|>) }
+"#,
+            expect![[r#"
+                bn world [type+name]
+                st WorldSnapshot []
+                fn go(…) []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn too_many_arguments() {
+        mark::check!(too_many_arguments);
+        check_scores(
+            r#"
+struct Foo;
+fn f(foo: &Foo) { f(foo, w<|>) }
+"#,
+            expect![[r#"
+                st Foo []
+                fn f(…) []
+                bn foo []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn guesses_macro_braces() {
+        check_edit(
+            "vec!",
+            r#"
+/// Creates a [`Vec`] containing the arguments.
+///
+/// ```
+/// let v = vec![1, 2, 3];
+/// assert_eq!(v[0], 1);
+/// assert_eq!(v[1], 2);
+/// assert_eq!(v[2], 3);
+/// ```
+macro_rules! vec { () => {} }
+
+fn fn main() { v<|> }
+"#,
+            r#"
+/// Creates a [`Vec`] containing the arguments.
+///
+/// ```
+/// let v = vec![1, 2, 3];
+/// assert_eq!(v[0], 1);
+/// assert_eq!(v[1], 2);
+/// assert_eq!(v[2], 3);
+/// ```
+macro_rules! vec { () => {} }
+
+fn fn main() { vec![$0] }
+"#,
+        );
+
+        check_edit(
+            "foo!",
+            r#"
+/// Foo
+///
+/// Don't call `fooo!()` `fooo!()`, or `_foo![]` `_foo![]`,
+/// call as `let _=foo!  { hello world };`
+macro_rules! foo { () => {} }
+fn main() { <|> }
+"#,
+            r#"
+/// Foo
+///
+/// Don't call `fooo!()` `fooo!()`, or `_foo![]` `_foo![]`,
+/// call as `let _=foo!  { hello world };`
+macro_rules! foo { () => {} }
+fn main() { foo! {$0} }
+"#,
+        )
+    }
+}
diff --git a/crates/ide/src/completion/test_utils.rs b/crates/ide/src/completion/test_utils.rs
new file mode 100644
index 000000000..1452d7e9e
--- /dev/null
+++ b/crates/ide/src/completion/test_utils.rs
@@ -0,0 +1,114 @@
+//! Runs completion for testing purposes.
+
+use hir::Semantics;
+use itertools::Itertools;
+use stdx::{format_to, trim_indent};
+use syntax::{AstNode, NodeOrToken, SyntaxElement};
+use test_utils::assert_eq_text;
+
+use crate::{
+    completion::{completion_item::CompletionKind, CompletionConfig},
+    mock_analysis::analysis_and_position,
+    CompletionItem,
+};
+
+pub(crate) fn do_completion(code: &str, kind: CompletionKind) -> Vec<CompletionItem> {
+    do_completion_with_config(CompletionConfig::default(), code, kind)
+}
+
+pub(crate) fn do_completion_with_config(
+    config: CompletionConfig,
+    code: &str,
+    kind: CompletionKind,
+) -> Vec<CompletionItem> {
+    let mut kind_completions: Vec<CompletionItem> = get_all_completion_items(config, code)
+        .into_iter()
+        .filter(|c| c.completion_kind == kind)
+        .collect();
+    kind_completions.sort_by(|l, r| l.label().cmp(r.label()));
+    kind_completions
+}
+
+pub(crate) fn completion_list(code: &str, kind: CompletionKind) -> String {
+    completion_list_with_config(CompletionConfig::default(), code, kind)
+}
+
+pub(crate) fn completion_list_with_config(
+    config: CompletionConfig,
+    code: &str,
+    kind: CompletionKind,
+) -> String {
+    let mut kind_completions: Vec<CompletionItem> = get_all_completion_items(config, code)
+        .into_iter()
+        .filter(|c| c.completion_kind == kind)
+        .collect();
+    kind_completions.sort_by_key(|c| c.label().to_owned());
+    let label_width = kind_completions
+        .iter()
+        .map(|it| monospace_width(it.label()))
+        .max()
+        .unwrap_or_default()
+        .min(16);
+    kind_completions
+        .into_iter()
+        .map(|it| {
+            let tag = it.kind().unwrap().tag();
+            let var_name = format!("{} {}", tag, it.label());
+            let mut buf = var_name;
+            if let Some(detail) = it.detail() {
+                let width = label_width.saturating_sub(monospace_width(it.label()));
+                format_to!(buf, "{:width$} {}", "", detail, width = width);
+            }
+            format_to!(buf, "\n");
+            buf
+        })
+        .collect()
+}
+
+fn monospace_width(s: &str) -> usize {
+    s.chars().count()
+}
+
+pub(crate) fn check_edit(what: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
+    check_edit_with_config(CompletionConfig::default(), what, ra_fixture_before, ra_fixture_after)
+}
+
+pub(crate) fn check_edit_with_config(
+    config: CompletionConfig,
+    what: &str,
+    ra_fixture_before: &str,
+    ra_fixture_after: &str,
+) {
+    let ra_fixture_after = trim_indent(ra_fixture_after);
+    let (analysis, position) = analysis_and_position(ra_fixture_before);
+    let completions: Vec<CompletionItem> =
+        analysis.completions(&config, position).unwrap().unwrap().into();
+    let (completion,) = completions
+        .iter()
+        .filter(|it| it.lookup() == what)
+        .collect_tuple()
+        .unwrap_or_else(|| panic!("can't find {:?} completion in {:#?}", what, completions));
+    let mut actual = analysis.file_text(position.file_id).unwrap().to_string();
+    completion.text_edit().apply(&mut actual);
+    assert_eq_text!(&ra_fixture_after, &actual)
+}
+
+pub(crate) fn check_pattern_is_applicable(code: &str, check: fn(SyntaxElement) -> bool) {
+    let (analysis, pos) = analysis_and_position(code);
+    analysis
+        .with_db(|db| {
+            let sema = Semantics::new(db);
+            let original_file = sema.parse(pos.file_id);
+            let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
+            assert!(check(NodeOrToken::Token(token)));
+        })
+        .unwrap();
+}
+
+pub(crate) fn get_all_completion_items(
+    config: CompletionConfig,
+    code: &str,
+) -> Vec<CompletionItem> {
+    let (analysis, position) = analysis_and_position(code);
+    analysis.completions(&config, position).unwrap().unwrap().into()
+}
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
new file mode 100644
index 000000000..b2b972b02
--- /dev/null
+++ b/crates/ide/src/diagnostics.rs
@@ -0,0 +1,746 @@
+//! Collects diagnostics & fixits  for a single file.
+//!
+//! The tricky bit here is that diagnostics are produced by hir in terms of
+//! macro-expanded files, but we need to present them to the users in terms of
+//! original files. So we need to map the ranges.
+
+mod fixes;
+
+use std::cell::RefCell;
+
+use base_db::SourceDatabase;
+use hir::{diagnostics::DiagnosticSinkBuilder, Semantics};
+use ide_db::RootDatabase;
+use itertools::Itertools;
+use rustc_hash::FxHashSet;
+use syntax::{
+    ast::{self, AstNode},
+    SyntaxNode, TextRange, T,
+};
+use text_edit::TextEdit;
+
+use crate::{FileId, Label, SourceChange, SourceFileEdit};
+
+use self::fixes::DiagnosticWithFix;
+
+#[derive(Debug)]
+pub struct Diagnostic {
+    // pub name: Option<String>,
+    pub message: String,
+    pub range: TextRange,
+    pub severity: Severity,
+    pub fix: Option<Fix>,
+}
+
+#[derive(Debug)]
+pub struct Fix {
+    pub label: Label,
+    pub source_change: SourceChange,
+    /// Allows to trigger the fix only when the caret is in the range given
+    pub fix_trigger_range: TextRange,
+}
+
+impl Fix {
+    fn new(label: &str, source_change: SourceChange, fix_trigger_range: TextRange) -> Self {
+        let label = Label::new(label);
+        Self { label, source_change, fix_trigger_range }
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Severity {
+    Error,
+    WeakWarning,
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct DiagnosticsConfig {
+    pub disable_experimental: bool,
+    pub disabled: FxHashSet<String>,
+}
+
+pub(crate) fn diagnostics(
+    db: &RootDatabase,
+    config: &DiagnosticsConfig,
+    file_id: FileId,
+) -> Vec<Diagnostic> {
+    let _p = profile::span("diagnostics");
+    let sema = Semantics::new(db);
+    let parse = db.parse(file_id);
+    let mut res = Vec::new();
+
+    // [#34344] Only take first 128 errors to prevent slowing down editor/ide, the number 128 is chosen arbitrarily.
+    res.extend(parse.errors().iter().take(128).map(|err| Diagnostic {
+        // name: None,
+        range: err.range(),
+        message: format!("Syntax Error: {}", err),
+        severity: Severity::Error,
+        fix: None,
+    }));
+
+    for node in parse.tree().syntax().descendants() {
+        check_unnecessary_braces_in_use_statement(&mut res, file_id, &node);
+        check_struct_shorthand_initialization(&mut res, file_id, &node);
+    }
+    let res = RefCell::new(res);
+    let sink_builder = DiagnosticSinkBuilder::new()
+        .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        .on::<hir::diagnostics::MissingFields, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        .on::<hir::diagnostics::NoSuchField, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        // Only collect experimental diagnostics when they're enabled.
+        .filter(|diag| !(diag.is_experimental() && config.disable_experimental))
+        .filter(|diag| !config.disabled.contains(diag.code().as_str()));
+
+    // Finalize the `DiagnosticSink` building process.
+    let mut sink = sink_builder
+        // Diagnostics not handled above get no fix and default treatment.
+        .build(|d| {
+            res.borrow_mut().push(Diagnostic {
+                // name: Some(d.name().into()),
+                message: d.message(),
+                range: sema.diagnostics_display_range(d).range,
+                severity: Severity::Error,
+                fix: None,
+            })
+        });
+
+    if let Some(m) = sema.to_module_def(file_id) {
+        m.diagnostics(db, &mut sink);
+    };
+    drop(sink);
+    res.into_inner()
+}
+
+fn diagnostic_with_fix<D: DiagnosticWithFix>(d: &D, sema: &Semantics<RootDatabase>) -> Diagnostic {
+    Diagnostic {
+        // name: Some(d.name().into()),
+        range: sema.diagnostics_display_range(d).range,
+        message: d.message(),
+        severity: Severity::Error,
+        fix: d.fix(&sema),
+    }
+}
+
+fn check_unnecessary_braces_in_use_statement(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let use_tree_list = ast::UseTreeList::cast(node.clone())?;
+    if let Some((single_use_tree,)) = use_tree_list.use_trees().collect_tuple() {
+        let use_range = use_tree_list.syntax().text_range();
+        let edit =
+            text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(&single_use_tree)
+                .unwrap_or_else(|| {
+                    let to_replace = single_use_tree.syntax().text().to_string();
+                    let mut edit_builder = TextEdit::builder();
+                    edit_builder.delete(use_range);
+                    edit_builder.insert(use_range.start(), to_replace);
+                    edit_builder.finish()
+                });
+
+        acc.push(Diagnostic {
+            // name: None,
+            range: use_range,
+            message: "Unnecessary braces in use statement".to_string(),
+            severity: Severity::WeakWarning,
+            fix: Some(Fix::new(
+                "Remove unnecessary braces",
+                SourceFileEdit { file_id, edit }.into(),
+                use_range,
+            )),
+        });
+    }
+
+    Some(())
+}
+
+fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
+    single_use_tree: &ast::UseTree,
+) -> Option<TextEdit> {
+    let use_tree_list_node = single_use_tree.syntax().parent()?;
+    if single_use_tree.path()?.segment()?.syntax().first_child_or_token()?.kind() == T![self] {
+        let start = use_tree_list_node.prev_sibling_or_token()?.text_range().start();
+        let end = use_tree_list_node.text_range().end();
+        return Some(TextEdit::delete(TextRange::new(start, end)));
+    }
+    None
+}
+
+fn check_struct_shorthand_initialization(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let record_lit = ast::RecordExpr::cast(node.clone())?;
+    let record_field_list = record_lit.record_expr_field_list()?;
+    for record_field in record_field_list.fields() {
+        if let (Some(name_ref), Some(expr)) = (record_field.name_ref(), record_field.expr()) {
+            let field_name = name_ref.syntax().text().to_string();
+            let field_expr = expr.syntax().text().to_string();
+            let field_name_is_tup_index = name_ref.as_tuple_field().is_some();
+            if field_name == field_expr && !field_name_is_tup_index {
+                let mut edit_builder = TextEdit::builder();
+                edit_builder.delete(record_field.syntax().text_range());
+                edit_builder.insert(record_field.syntax().text_range().start(), field_name);
+                let edit = edit_builder.finish();
+
+                let field_range = record_field.syntax().text_range();
+                acc.push(Diagnostic {
+                    // name: None,
+                    range: field_range,
+                    message: "Shorthand struct initialization".to_string(),
+                    severity: Severity::WeakWarning,
+                    fix: Some(Fix::new(
+                        "Use struct shorthand initialization",
+                        SourceFileEdit { file_id, edit }.into(),
+                        field_range,
+                    )),
+                });
+            }
+        }
+    }
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use stdx::trim_indent;
+    use test_utils::assert_eq_text;
+
+    use crate::{
+        mock_analysis::{analysis_and_position, single_file, MockAnalysis},
+        DiagnosticsConfig,
+    };
+
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * this diagnostic fix trigger range touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
+    fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let after = trim_indent(ra_fixture_after);
+
+        let (analysis, file_position) = analysis_and_position(ra_fixture_before);
+        let diagnostic = analysis
+            .diagnostics(&DiagnosticsConfig::default(), file_position.file_id)
+            .unwrap()
+            .pop()
+            .unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_change.source_file_edits.pop().unwrap().edit;
+        let target_file_contents = analysis.file_text(file_position.file_id).unwrap();
+        let actual = {
+            let mut actual = target_file_contents.to_string();
+            edit.apply(&mut actual);
+            actual
+        };
+
+        assert_eq_text!(&after, &actual);
+        assert!(
+            fix.fix_trigger_range.start() <= file_position.offset
+                && fix.fix_trigger_range.end() >= file_position.offset,
+            "diagnostic fix range {:?} does not touch cursor position {:?}",
+            fix.fix_trigger_range,
+            file_position.offset
+        );
+    }
+
+    /// Checks that a diagnostic applies to the file containing the `<|>` cursor marker
+    /// which has a fix that can apply to other files.
+    fn check_apply_diagnostic_fix_in_other_file(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let ra_fixture_after = &trim_indent(ra_fixture_after);
+        let (analysis, file_pos) = analysis_and_position(ra_fixture_before);
+        let current_file_id = file_pos.file_id;
+        let diagnostic = analysis
+            .diagnostics(&DiagnosticsConfig::default(), current_file_id)
+            .unwrap()
+            .pop()
+            .unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_change.source_file_edits.pop().unwrap();
+        let changed_file_id = edit.file_id;
+        let before = analysis.file_text(changed_file_id).unwrap();
+        let actual = {
+            let mut actual = before.to_string();
+            edit.edit.apply(&mut actual);
+            actual
+        };
+        assert_eq_text!(ra_fixture_after, &actual);
+    }
+
+    /// Takes a multi-file input fixture with annotated cursor position and checks that no diagnostics
+    /// apply to the file containing the cursor.
+    fn check_no_diagnostics(ra_fixture: &str) {
+        let mock = MockAnalysis::with_files(ra_fixture);
+        let files = mock.files().map(|(it, _)| it).collect::<Vec<_>>();
+        let analysis = mock.analysis();
+        let diagnostics = files
+            .into_iter()
+            .flat_map(|file_id| {
+                analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap()
+            })
+            .collect::<Vec<_>>();
+        assert_eq!(diagnostics.len(), 0, "unexpected diagnostics:\n{:#?}", diagnostics);
+    }
+
+    fn check_expect(ra_fixture: &str, expect: Expect) {
+        let (analysis, file_id) = single_file(ra_fixture);
+        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        expect.assert_debug_eq(&diagnostics)
+    }
+
+    #[test]
+    fn test_wrap_return_type() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn div(x: i32, y: i32) -> Result<i32, ()> {
+    if y == 0 {
+        return Err(());
+    }
+    x / y<|>
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+fn div(x: i32, y: i32) -> Result<i32, ()> {
+    if y == 0 {
+        return Err(());
+    }
+    Ok(x / y)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_generic_functions() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn div<T>(x: T) -> Result<T, i32> {
+    if x == 0 {
+        return Err(7);
+    }
+    <|>x
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+fn div<T>(x: T) -> Result<T, i32> {
+    if x == 0 {
+        return Err(7);
+    }
+    Ok(x)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_type_aliases() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+type MyResult<T> = Result<T, ()>;
+
+fn div(x: i32, y: i32) -> MyResult<i32> {
+    if y == 0 {
+        return Err(());
+    }
+    x <|>/ y
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+type MyResult<T> = Result<T, ()>;
+
+fn div(x: i32, y: i32) -> MyResult<i32> {
+    if y == 0 {
+        return Err(());
+    }
+    Ok(x / y)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_expr_type_does_not_match_ok_type() {
+        check_no_diagnostics(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn foo() -> Result<(), i32> { 0 }
+
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_return_type_is_not_result() {
+        check_no_diagnostics(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+enum SomeOtherEnum { Ok(i32), Err(String) }
+
+fn foo() -> SomeOtherEnum { 0 }
+
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_empty() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct {<|>};
+}
+"#,
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct { one: (), two: ()};
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_self() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32 }
+
+impl TestStruct {
+    fn test_fn() { let s = Self {<|>}; }
+}
+"#,
+            r#"
+struct TestStruct { one: i32 }
+
+impl TestStruct {
+    fn test_fn() { let s = Self { one: ()}; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_enum() {
+        check_fix(
+            r#"
+enum Expr {
+    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
+}
+
+impl Expr {
+    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
+        Expr::Bin {<|> }
+    }
+}
+"#,
+            r#"
+enum Expr {
+    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
+}
+
+impl Expr {
+    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
+        Expr::Bin { lhs: (), rhs: () }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_partial() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct{ two: 2<|> };
+}
+"#,
+            r"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct{ two: 2, one: () };
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic() {
+        check_no_diagnostics(
+            r"
+            struct TestStruct { one: i32, two: i64 }
+
+            fn test_fn() {
+                let one = 1;
+                let s = TestStruct{ one, two: 2 };
+            }
+        ",
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic_on_spread() {
+        check_no_diagnostics(
+            r"
+            struct TestStruct { one: i32, two: i64 }
+
+            fn test_fn() {
+                let one = 1;
+                let s = TestStruct{ ..a };
+            }
+        ",
+        );
+    }
+
+    #[test]
+    fn test_unresolved_module_diagnostic() {
+        check_expect(
+            r#"mod foo;"#,
+            expect![[r#"
+                [
+                    Diagnostic {
+                        message: "unresolved module",
+                        range: 0..8,
+                        severity: Error,
+                        fix: Some(
+                            Fix {
+                                label: "Create module",
+                                source_change: SourceChange {
+                                    source_file_edits: [],
+                                    file_system_edits: [
+                                        CreateFile {
+                                            anchor: FileId(
+                                                1,
+                                            ),
+                                            dst: "foo.rs",
+                                        },
+                                    ],
+                                    is_snippet: false,
+                                },
+                                fix_trigger_range: 0..8,
+                            },
+                        ),
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn range_mapping_out_of_macros() {
+        // FIXME: this is very wrong, but somewhat tricky to fix.
+        check_fix(
+            r#"
+fn some() {}
+fn items() {}
+fn here() {}
+
+macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
+
+fn main() {
+    let _x = id![Foo { a: <|>42 }];
+}
+
+pub struct Foo { pub a: i32, pub b: i32 }
+"#,
+            r#"
+fn {a:42, b: ()} {}
+fn items() {}
+fn here() {}
+
+macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
+
+fn main() {
+    let _x = id![Foo { a: 42 }];
+}
+
+pub struct Foo { pub a: i32, pub b: i32 }
+"#,
+        );
+    }
+
+    #[test]
+    fn test_check_unnecessary_braces_in_use_statement() {
+        check_no_diagnostics(
+            r#"
+use a;
+use a::{c, d::e};
+"#,
+        );
+        check_fix(r#"use {<|>b};"#, r#"use b;"#);
+        check_fix(r#"use {b<|>};"#, r#"use b;"#);
+        check_fix(r#"use a::{c<|>};"#, r#"use a::c;"#);
+        check_fix(r#"use a::{self<|>};"#, r#"use a;"#);
+        check_fix(r#"use a::{c, d::{e<|>}};"#, r#"use a::{c, d::e};"#);
+    }
+
+    #[test]
+    fn test_check_struct_shorthand_initialization() {
+        check_no_diagnostics(
+            r#"
+struct A { a: &'static str }
+fn main() { A { a: "hello" } }
+"#,
+        );
+        check_no_diagnostics(
+            r#"
+struct A(usize);
+fn main() { A { 0: 0 } }
+"#,
+        );
+
+        check_fix(
+            r#"
+struct A { a: &'static str }
+fn main() {
+    let a = "haha";
+    A { a<|>: a }
+}
+"#,
+            r#"
+struct A { a: &'static str }
+fn main() {
+    let a = "haha";
+    A { a }
+}
+"#,
+        );
+
+        check_fix(
+            r#"
+struct A { a: &'static str, b: &'static str }
+fn main() {
+    let a = "haha";
+    let b = "bb";
+    A { a<|>: a, b }
+}
+"#,
+            r#"
+struct A { a: &'static str, b: &'static str }
+fn main() {
+    let a = "haha";
+    let b = "bb";
+    A { a, b }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_add_field_from_usage() {
+        check_fix(
+            r"
+fn main() {
+    Foo { bar: 3, baz<|>: false};
+}
+struct Foo {
+    bar: i32
+}
+",
+            r"
+fn main() {
+    Foo { bar: 3, baz: false};
+}
+struct Foo {
+    bar: i32,
+    baz: bool
+}
+",
+        )
+    }
+
+    #[test]
+    fn test_add_field_in_other_file_from_usage() {
+        check_apply_diagnostic_fix_in_other_file(
+            r"
+            //- /main.rs
+            mod foo;
+
+            fn main() {
+                <|>foo::Foo { bar: 3, baz: false};
+            }
+            //- /foo.rs
+            struct Foo {
+                bar: i32
+            }
+            ",
+            r"
+            struct Foo {
+                bar: i32,
+                pub(crate) baz: bool
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn test_disabled_diagnostics() {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("unresolved-module".into());
+
+        let (analysis, file_id) = single_file(r#"mod foo;"#);
+
+        let diagnostics = analysis.diagnostics(&config, file_id).unwrap();
+        assert!(diagnostics.is_empty());
+
+        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        assert!(!diagnostics.is_empty());
+    }
+}
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
new file mode 100644
index 000000000..68ae1c239
--- /dev/null
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -0,0 +1,175 @@
+//! Provides a way to attach fixes to the diagnostics.
+//! The same module also has all curret custom fixes for the diagnostics implemented.
+use base_db::FileId;
+use hir::{
+    db::AstDatabase,
+    diagnostics::{Diagnostic, MissingFields, MissingOkInTailExpr, NoSuchField, UnresolvedModule},
+    HasSource, HirDisplay, Semantics, VariantDef,
+};
+use ide_db::{
+    source_change::{FileSystemEdit, SourceFileEdit},
+    RootDatabase,
+};
+use syntax::{
+    algo,
+    ast::{self, edit::IndentLevel, make},
+    AstNode,
+};
+use text_edit::TextEdit;
+
+use crate::diagnostics::Fix;
+
+/// A [Diagnostic] that potentially has a fix available.
+///
+/// [Diagnostic]: hir::diagnostics::Diagnostic
+pub trait DiagnosticWithFix: Diagnostic {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix>;
+}
+
+impl DiagnosticWithFix for UnresolvedModule {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+        let root = sema.db.parse_or_expand(self.file)?;
+        let unresolved_module = self.decl.to_node(&root);
+        Some(Fix::new(
+            "Create module",
+            FileSystemEdit::CreateFile {
+                anchor: self.file.original_file(sema.db),
+                dst: self.candidate.clone(),
+            }
+            .into(),
+            unresolved_module.syntax().text_range(),
+        ))
+    }
+}
+
+impl DiagnosticWithFix for NoSuchField {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+        let root = sema.db.parse_or_expand(self.file)?;
+        missing_record_expr_field_fix(
+            &sema,
+            self.file.original_file(sema.db),
+            &self.field.to_node(&root),
+        )
+    }
+}
+
+impl DiagnosticWithFix for MissingFields {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+        // Note that although we could add a diagnostics to
+        // fill the missing tuple field, e.g :
+        // `struct A(usize);`
+        // `let a = A { 0: () }`
+        // but it is uncommon usage and it should not be encouraged.
+        if self.missed_fields.iter().any(|it| it.as_tuple_index().is_some()) {
+            return None;
+        }
+
+        let root = sema.db.parse_or_expand(self.file)?;
+        let old_field_list = self.field_list_parent.to_node(&root).record_expr_field_list()?;
+        let mut new_field_list = old_field_list.clone();
+        for f in self.missed_fields.iter() {
+            let field =
+                make::record_expr_field(make::name_ref(&f.to_string()), Some(make::expr_unit()));
+            new_field_list = new_field_list.append_field(&field);
+        }
+
+        let edit = {
+            let mut builder = TextEdit::builder();
+            algo::diff(&old_field_list.syntax(), &new_field_list.syntax())
+                .into_text_edit(&mut builder);
+            builder.finish()
+        };
+        Some(Fix::new(
+            "Fill struct fields",
+            SourceFileEdit { file_id: self.file.original_file(sema.db), edit }.into(),
+            sema.original_range(&old_field_list.syntax()).range,
+        ))
+    }
+}
+
+impl DiagnosticWithFix for MissingOkInTailExpr {
+    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+        let root = sema.db.parse_or_expand(self.file)?;
+        let tail_expr = self.expr.to_node(&root);
+        let tail_expr_range = tail_expr.syntax().text_range();
+        let edit = TextEdit::replace(tail_expr_range, format!("Ok({})", tail_expr.syntax()));
+        let source_change =
+            SourceFileEdit { file_id: self.file.original_file(sema.db), edit }.into();
+        Some(Fix::new("Wrap with ok", source_change, tail_expr_range))
+    }
+}
+
+fn missing_record_expr_field_fix(
+    sema: &Semantics<RootDatabase>,
+    usage_file_id: FileId,
+    record_expr_field: &ast::RecordExprField,
+) -> Option<Fix> {
+    let record_lit = ast::RecordExpr::cast(record_expr_field.syntax().parent()?.parent()?)?;
+    let def_id = sema.resolve_variant(record_lit)?;
+    let module;
+    let def_file_id;
+    let record_fields = match VariantDef::from(def_id) {
+        VariantDef::Struct(s) => {
+            module = s.module(sema.db);
+            let source = s.source(sema.db);
+            def_file_id = source.file_id;
+            let fields = source.value.field_list()?;
+            record_field_list(fields)?
+        }
+        VariantDef::Union(u) => {
+            module = u.module(sema.db);
+            let source = u.source(sema.db);
+            def_file_id = source.file_id;
+            source.value.record_field_list()?
+        }
+        VariantDef::EnumVariant(e) => {
+            module = e.module(sema.db);
+            let source = e.source(sema.db);
+            def_file_id = source.file_id;
+            let fields = source.value.field_list()?;
+            record_field_list(fields)?
+        }
+    };
+    let def_file_id = def_file_id.original_file(sema.db);
+
+    let new_field_type = sema.type_of_expr(&record_expr_field.expr()?)?;
+    if new_field_type.is_unknown() {
+        return None;
+    }
+    let new_field = make::record_field(
+        record_expr_field.field_name()?,
+        make::ty(&new_field_type.display_source_code(sema.db, module.into()).ok()?),
+    );
+
+    let last_field = record_fields.fields().last()?;
+    let last_field_syntax = last_field.syntax();
+    let indent = IndentLevel::from_node(last_field_syntax);
+
+    let mut new_field = new_field.to_string();
+    if usage_file_id != def_file_id {
+        new_field = format!("pub(crate) {}", new_field);
+    }
+    new_field = format!("\n{}{}", indent, new_field);
+
+    let needs_comma = !last_field_syntax.to_string().ends_with(',');
+    if needs_comma {
+        new_field = format!(",{}", new_field);
+    }
+
+    let source_change = SourceFileEdit {
+        file_id: def_file_id,
+        edit: TextEdit::insert(last_field_syntax.text_range().end(), new_field),
+    };
+    return Some(Fix::new(
+        "Create field",
+        source_change.into(),
+        record_expr_field.syntax().text_range(),
+    ));
+
+    fn record_field_list(field_def_list: ast::FieldList) -> Option<ast::RecordFieldList> {
+        match field_def_list {
+            ast::FieldList::RecordFieldList(it) => Some(it),
+            ast::FieldList::TupleFieldList(_) => None,
+        }
+    }
+}
diff --git a/crates/ide/src/display.rs b/crates/ide/src/display.rs
new file mode 100644
index 000000000..41b5bdc49
--- /dev/null
+++ b/crates/ide/src/display.rs
@@ -0,0 +1,83 @@
+//! This module contains utilities for turning SyntaxNodes and HIR types
+//! into types that may be used to render in a UI.
+
+mod navigation_target;
+mod short_label;
+
+use syntax::{
+    ast::{self, AstNode, AttrsOwner, GenericParamsOwner, NameOwner},
+    SyntaxKind::{ATTR, COMMENT},
+};
+
+use ast::VisibilityOwner;
+use stdx::format_to;
+
+pub use navigation_target::NavigationTarget;
+pub(crate) use navigation_target::{ToNav, TryToNav};
+pub(crate) use short_label::ShortLabel;
+
+pub(crate) fn function_declaration(node: &ast::Fn) -> String {
+    let mut buf = String::new();
+    if let Some(vis) = node.visibility() {
+        format_to!(buf, "{} ", vis);
+    }
+    if node.async_token().is_some() {
+        format_to!(buf, "async ");
+    }
+    if node.const_token().is_some() {
+        format_to!(buf, "const ");
+    }
+    if node.unsafe_token().is_some() {
+        format_to!(buf, "unsafe ");
+    }
+    if let Some(abi) = node.abi() {
+        // Keyword `extern` is included in the string.
+        format_to!(buf, "{} ", abi);
+    }
+    if let Some(name) = node.name() {
+        format_to!(buf, "fn {}", name)
+    }
+    if let Some(type_params) = node.generic_param_list() {
+        format_to!(buf, "{}", type_params);
+    }
+    if let Some(param_list) = node.param_list() {
+        format_to!(buf, "{}", param_list);
+    }
+    if let Some(ret_type) = node.ret_type() {
+        if ret_type.ty().is_some() {
+            format_to!(buf, " {}", ret_type);
+        }
+    }
+    if let Some(where_clause) = node.where_clause() {
+        format_to!(buf, "\n{}", where_clause);
+    }
+    buf
+}
+
+pub(crate) fn const_label(node: &ast::Const) -> String {
+    let label: String = node
+        .syntax()
+        .children_with_tokens()
+        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
+        .map(|node| node.to_string())
+        .collect();
+
+    label.trim().to_owned()
+}
+
+pub(crate) fn type_label(node: &ast::TypeAlias) -> String {
+    let label: String = node
+        .syntax()
+        .children_with_tokens()
+        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
+        .map(|node| node.to_string())
+        .collect();
+
+    label.trim().to_owned()
+}
+
+pub(crate) fn macro_label(node: &ast::MacroCall) -> String {
+    let name = node.name().map(|name| name.syntax().text().to_string()).unwrap_or_default();
+    let vis = if node.has_atom_attr("macro_export") { "#[macro_export]\n" } else { "" };
+    format!("{}macro_rules! {}", vis, name)
+}
diff --git a/crates/ide/src/display/navigation_target.rs b/crates/ide/src/display/navigation_target.rs
new file mode 100644
index 000000000..1ee80c2dd
--- /dev/null
+++ b/crates/ide/src/display/navigation_target.rs
@@ -0,0 +1,491 @@
+//! FIXME: write short doc here
+
+use base_db::{FileId, SourceDatabase};
+use either::Either;
+use hir::{original_range, AssocItem, FieldSource, HasSource, InFile, ModuleSource};
+use ide_db::{defs::Definition, RootDatabase};
+use syntax::{
+    ast::{self, DocCommentsOwner, NameOwner},
+    match_ast, AstNode, SmolStr,
+    SyntaxKind::{self, IDENT_PAT, TYPE_PARAM},
+    TextRange,
+};
+
+use crate::FileSymbol;
+
+use super::short_label::ShortLabel;
+
+/// `NavigationTarget` represents and element in the editor's UI which you can
+/// click on to navigate to a particular piece of code.
+///
+/// Typically, a `NavigationTarget` corresponds to some element in the source
+/// code, like a function or a struct, but this is not strictly required.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct NavigationTarget {
+    pub file_id: FileId,
+    /// Range which encompasses the whole element.
+    ///
+    /// Should include body, doc comments, attributes, etc.
+    ///
+    /// Clients should use this range to answer "is the cursor inside the
+    /// element?" question.
+    pub full_range: TextRange,
+    /// A "most interesting" range withing the `full_range`.
+    ///
+    /// Typically, `full_range` is the whole syntax node, including doc
+    /// comments, and `focus_range` is the range of the identifier. "Most
+    /// interesting" range within the full range, typically the range of
+    /// identifier.
+    ///
+    /// Clients should place the cursor on this range when navigating to this target.
+    pub focus_range: Option<TextRange>,
+    pub name: SmolStr,
+    pub kind: SyntaxKind,
+    pub container_name: Option<SmolStr>,
+    pub description: Option<String>,
+    pub docs: Option<String>,
+}
+
+pub(crate) trait ToNav {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget;
+}
+
+pub(crate) trait TryToNav {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget>;
+}
+
+impl NavigationTarget {
+    pub fn focus_or_full_range(&self) -> TextRange {
+        self.focus_range.unwrap_or(self.full_range)
+    }
+
+    pub(crate) fn from_module_to_decl(db: &RootDatabase, module: hir::Module) -> NavigationTarget {
+        let name = module.name(db).map(|it| it.to_string().into()).unwrap_or_default();
+        if let Some(src) = module.declaration_source(db) {
+            let frange = original_range(db, src.as_ref().map(|it| it.syntax()));
+            let mut res = NavigationTarget::from_syntax(
+                frange.file_id,
+                name,
+                None,
+                frange.range,
+                src.value.syntax().kind(),
+            );
+            res.docs = src.value.doc_comment_text();
+            res.description = src.value.short_label();
+            return res;
+        }
+        module.to_nav(db)
+    }
+
+    #[cfg(test)]
+    pub(crate) fn assert_match(&self, expected: &str) {
+        let actual = self.debug_render();
+        test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
+    }
+
+    #[cfg(test)]
+    pub(crate) fn debug_render(&self) -> String {
+        let mut buf =
+            format!("{} {:?} {:?} {:?}", self.name, self.kind, self.file_id, self.full_range);
+        if let Some(focus_range) = self.focus_range {
+            buf.push_str(&format!(" {:?}", focus_range))
+        }
+        if let Some(container_name) = &self.container_name {
+            buf.push_str(&format!(" {}", container_name))
+        }
+        buf
+    }
+
+    /// Allows `NavigationTarget` to be created from a `NameOwner`
+    pub(crate) fn from_named(
+        db: &RootDatabase,
+        node: InFile<&dyn ast::NameOwner>,
+    ) -> NavigationTarget {
+        let name =
+            node.value.name().map(|it| it.text().clone()).unwrap_or_else(|| SmolStr::new("_"));
+        let focus_range =
+            node.value.name().map(|it| original_range(db, node.with_value(it.syntax())).range);
+        let frange = original_range(db, node.map(|it| it.syntax()));
+
+        NavigationTarget::from_syntax(
+            frange.file_id,
+            name,
+            focus_range,
+            frange.range,
+            node.value.syntax().kind(),
+        )
+    }
+
+    /// Allows `NavigationTarget` to be created from a `DocCommentsOwner` and a `NameOwner`
+    pub(crate) fn from_doc_commented(
+        db: &RootDatabase,
+        named: InFile<&dyn ast::NameOwner>,
+        node: InFile<&dyn ast::DocCommentsOwner>,
+    ) -> NavigationTarget {
+        let name =
+            named.value.name().map(|it| it.text().clone()).unwrap_or_else(|| SmolStr::new("_"));
+        let frange = original_range(db, node.map(|it| it.syntax()));
+
+        NavigationTarget::from_syntax(
+            frange.file_id,
+            name,
+            None,
+            frange.range,
+            node.value.syntax().kind(),
+        )
+    }
+
+    fn from_syntax(
+        file_id: FileId,
+        name: SmolStr,
+        focus_range: Option<TextRange>,
+        full_range: TextRange,
+        kind: SyntaxKind,
+    ) -> NavigationTarget {
+        NavigationTarget {
+            file_id,
+            name,
+            kind,
+            full_range,
+            focus_range,
+            container_name: None,
+            description: None,
+            docs: None,
+        }
+    }
+}
+
+impl ToNav for FileSymbol {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        NavigationTarget {
+            file_id: self.file_id,
+            name: self.name.clone(),
+            kind: self.kind,
+            full_range: self.range,
+            focus_range: self.name_range,
+            container_name: self.container_name.clone(),
+            description: description_from_symbol(db, self),
+            docs: docs_from_symbol(db, self),
+        }
+    }
+}
+
+impl TryToNav for Definition {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        match self {
+            Definition::Macro(it) => Some(it.to_nav(db)),
+            Definition::Field(it) => Some(it.to_nav(db)),
+            Definition::ModuleDef(it) => it.try_to_nav(db),
+            Definition::SelfType(it) => Some(it.to_nav(db)),
+            Definition::Local(it) => Some(it.to_nav(db)),
+            Definition::TypeParam(it) => Some(it.to_nav(db)),
+        }
+    }
+}
+
+impl TryToNav for hir::ModuleDef {
+    fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
+        let res = match self {
+            hir::ModuleDef::Module(it) => it.to_nav(db),
+            hir::ModuleDef::Function(it) => it.to_nav(db),
+            hir::ModuleDef::Adt(it) => it.to_nav(db),
+            hir::ModuleDef::EnumVariant(it) => it.to_nav(db),
+            hir::ModuleDef::Const(it) => it.to_nav(db),
+            hir::ModuleDef::Static(it) => it.to_nav(db),
+            hir::ModuleDef::Trait(it) => it.to_nav(db),
+            hir::ModuleDef::TypeAlias(it) => it.to_nav(db),
+            hir::ModuleDef::BuiltinType(_) => return None,
+        };
+        Some(res)
+    }
+}
+
+pub(crate) trait ToNavFromAst {}
+impl ToNavFromAst for hir::Function {}
+impl ToNavFromAst for hir::Const {}
+impl ToNavFromAst for hir::Static {}
+impl ToNavFromAst for hir::Struct {}
+impl ToNavFromAst for hir::Enum {}
+impl ToNavFromAst for hir::EnumVariant {}
+impl ToNavFromAst for hir::Union {}
+impl ToNavFromAst for hir::TypeAlias {}
+impl ToNavFromAst for hir::Trait {}
+
+impl<D> ToNav for D
+where
+    D: HasSource + ToNavFromAst + Copy,
+    D::Ast: ast::DocCommentsOwner + ast::NameOwner + ShortLabel,
+{
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        let mut res =
+            NavigationTarget::from_named(db, src.as_ref().map(|it| it as &dyn ast::NameOwner));
+        res.docs = src.value.doc_comment_text();
+        res.description = src.value.short_label();
+        res
+    }
+}
+
+impl ToNav for hir::Module {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.definition_source(db);
+        let name = self.name(db).map(|it| it.to_string().into()).unwrap_or_default();
+        let (syntax, focus) = match &src.value {
+            ModuleSource::SourceFile(node) => (node.syntax(), None),
+            ModuleSource::Module(node) => {
+                (node.syntax(), node.name().map(|it| it.syntax().text_range()))
+            }
+        };
+        let frange = original_range(db, src.with_value(syntax));
+        NavigationTarget::from_syntax(frange.file_id, name, focus, frange.range, syntax.kind())
+    }
+}
+
+impl ToNav for hir::ImplDef {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        let derive_attr = self.is_builtin_derive(db);
+        let frange = if let Some(item) = &derive_attr {
+            original_range(db, item.syntax())
+        } else {
+            original_range(db, src.as_ref().map(|it| it.syntax()))
+        };
+        let focus_range = if derive_attr.is_some() {
+            None
+        } else {
+            src.value.self_ty().map(|ty| original_range(db, src.with_value(ty.syntax())).range)
+        };
+
+        NavigationTarget::from_syntax(
+            frange.file_id,
+            "impl".into(),
+            focus_range,
+            frange.range,
+            src.value.syntax().kind(),
+        )
+    }
+}
+
+impl ToNav for hir::Field {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+
+        match &src.value {
+            FieldSource::Named(it) => {
+                let mut res = NavigationTarget::from_named(db, src.with_value(it));
+                res.docs = it.doc_comment_text();
+                res.description = it.short_label();
+                res
+            }
+            FieldSource::Pos(it) => {
+                let frange = original_range(db, src.with_value(it.syntax()));
+                NavigationTarget::from_syntax(
+                    frange.file_id,
+                    "".into(),
+                    None,
+                    frange.range,
+                    it.syntax().kind(),
+                )
+            }
+        }
+    }
+}
+
+impl ToNav for hir::MacroDef {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        log::debug!("nav target {:#?}", src.value.syntax());
+        let mut res =
+            NavigationTarget::from_named(db, src.as_ref().map(|it| it as &dyn ast::NameOwner));
+        res.docs = src.value.doc_comment_text();
+        res
+    }
+}
+
+impl ToNav for hir::Adt {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        match self {
+            hir::Adt::Struct(it) => it.to_nav(db),
+            hir::Adt::Union(it) => it.to_nav(db),
+            hir::Adt::Enum(it) => it.to_nav(db),
+        }
+    }
+}
+
+impl ToNav for hir::AssocItem {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        match self {
+            AssocItem::Function(it) => it.to_nav(db),
+            AssocItem::Const(it) => it.to_nav(db),
+            AssocItem::TypeAlias(it) => it.to_nav(db),
+        }
+    }
+}
+
+impl ToNav for hir::Local {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        let node = match &src.value {
+            Either::Left(bind_pat) => {
+                bind_pat.name().map_or_else(|| bind_pat.syntax().clone(), |it| it.syntax().clone())
+            }
+            Either::Right(it) => it.syntax().clone(),
+        };
+        let full_range = original_range(db, src.with_value(&node));
+        let name = match self.name(db) {
+            Some(it) => it.to_string().into(),
+            None => "".into(),
+        };
+        NavigationTarget {
+            file_id: full_range.file_id,
+            name,
+            kind: IDENT_PAT,
+            full_range: full_range.range,
+            focus_range: None,
+            container_name: None,
+            description: None,
+            docs: None,
+        }
+    }
+}
+
+impl ToNav for hir::TypeParam {
+    fn to_nav(&self, db: &RootDatabase) -> NavigationTarget {
+        let src = self.source(db);
+        let full_range = match &src.value {
+            Either::Left(it) => it.syntax().text_range(),
+            Either::Right(it) => it.syntax().text_range(),
+        };
+        let focus_range = match &src.value {
+            Either::Left(_) => None,
+            Either::Right(it) => it.name().map(|it| it.syntax().text_range()),
+        };
+        NavigationTarget {
+            file_id: src.file_id.original_file(db),
+            name: self.name(db).to_string().into(),
+            kind: TYPE_PARAM,
+            full_range,
+            focus_range,
+            container_name: None,
+            description: None,
+            docs: None,
+        }
+    }
+}
+
+pub(crate) fn docs_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option<String> {
+    let parse = db.parse(symbol.file_id);
+    let node = symbol.ptr.to_node(parse.tree().syntax());
+
+    match_ast! {
+        match node {
+            ast::Fn(it) => it.doc_comment_text(),
+            ast::Struct(it) => it.doc_comment_text(),
+            ast::Enum(it) => it.doc_comment_text(),
+            ast::Trait(it) => it.doc_comment_text(),
+            ast::Module(it) => it.doc_comment_text(),
+            ast::TypeAlias(it) => it.doc_comment_text(),
+            ast::Const(it) => it.doc_comment_text(),
+            ast::Static(it) => it.doc_comment_text(),
+            ast::RecordField(it) => it.doc_comment_text(),
+            ast::Variant(it) => it.doc_comment_text(),
+            ast::MacroCall(it) => it.doc_comment_text(),
+            _ => None,
+        }
+    }
+}
+
+/// Get a description of a symbol.
+///
+/// e.g. `struct Name`, `enum Name`, `fn Name`
+pub(crate) fn description_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option<String> {
+    let parse = db.parse(symbol.file_id);
+    let node = symbol.ptr.to_node(parse.tree().syntax());
+
+    match_ast! {
+        match node {
+            ast::Fn(it) => it.short_label(),
+            ast::Struct(it) => it.short_label(),
+            ast::Enum(it) => it.short_label(),
+            ast::Trait(it) => it.short_label(),
+            ast::Module(it) => it.short_label(),
+            ast::TypeAlias(it) => it.short_label(),
+            ast::Const(it) => it.short_label(),
+            ast::Static(it) => it.short_label(),
+            ast::RecordField(it) => it.short_label(),
+            ast::Variant(it) => it.short_label(),
+            _ => None,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::expect;
+
+    use crate::{mock_analysis::single_file, Query};
+
+    #[test]
+    fn test_nav_for_symbol() {
+        let (analysis, _) = single_file(
+            r#"
+enum FooInner { }
+fn foo() { enum FooInner { } }
+"#,
+        );
+
+        let navs = analysis.symbol_search(Query::new("FooInner".to_string())).unwrap();
+        expect![[r#"
+            [
+                NavigationTarget {
+                    file_id: FileId(
+                        1,
+                    ),
+                    full_range: 0..17,
+                    focus_range: Some(
+                        5..13,
+                    ),
+                    name: "FooInner",
+                    kind: ENUM,
+                    container_name: None,
+                    description: Some(
+                        "enum FooInner",
+                    ),
+                    docs: None,
+                },
+                NavigationTarget {
+                    file_id: FileId(
+                        1,
+                    ),
+                    full_range: 29..46,
+                    focus_range: Some(
+                        34..42,
+                    ),
+                    name: "FooInner",
+                    kind: ENUM,
+                    container_name: Some(
+                        "foo",
+                    ),
+                    description: Some(
+                        "enum FooInner",
+                    ),
+                    docs: None,
+                },
+            ]
+        "#]]
+        .assert_debug_eq(&navs);
+    }
+
+    #[test]
+    fn test_world_symbols_are_case_sensitive() {
+        let (analysis, _) = single_file(
+            r#"
+fn foo() {}
+struct Foo;
+"#,
+        );
+
+        let navs = analysis.symbol_search(Query::new("foo".to_string())).unwrap();
+        assert_eq!(navs.len(), 2)
+    }
+}
diff --git a/crates/ide/src/display/short_label.rs b/crates/ide/src/display/short_label.rs
new file mode 100644
index 000000000..ea49d9f97
--- /dev/null
+++ b/crates/ide/src/display/short_label.rs
@@ -0,0 +1,111 @@
+//! FIXME: write short doc here
+
+use stdx::format_to;
+use syntax::ast::{self, AstNode, NameOwner, VisibilityOwner};
+
+pub(crate) trait ShortLabel {
+    fn short_label(&self) -> Option<String>;
+}
+
+impl ShortLabel for ast::Fn {
+    fn short_label(&self) -> Option<String> {
+        Some(crate::display::function_declaration(self))
+    }
+}
+
+impl ShortLabel for ast::Struct {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_node(self, "struct ")
+    }
+}
+
+impl ShortLabel for ast::Union {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_node(self, "union ")
+    }
+}
+
+impl ShortLabel for ast::Enum {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_node(self, "enum ")
+    }
+}
+
+impl ShortLabel for ast::Trait {
+    fn short_label(&self) -> Option<String> {
+        if self.unsafe_token().is_some() {
+            short_label_from_node(self, "unsafe trait ")
+        } else {
+            short_label_from_node(self, "trait ")
+        }
+    }
+}
+
+impl ShortLabel for ast::Module {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_node(self, "mod ")
+    }
+}
+
+impl ShortLabel for ast::SourceFile {
+    fn short_label(&self) -> Option<String> {
+        None
+    }
+}
+
+impl ShortLabel for ast::TypeAlias {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_node(self, "type ")
+    }
+}
+
+impl ShortLabel for ast::Const {
+    fn short_label(&self) -> Option<String> {
+        let mut new_buf = short_label_from_ty(self, self.ty(), "const ")?;
+        if let Some(expr) = self.body() {
+            format_to!(new_buf, " = {}", expr.syntax());
+        }
+        Some(new_buf)
+    }
+}
+
+impl ShortLabel for ast::Static {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_ty(self, self.ty(), "static ")
+    }
+}
+
+impl ShortLabel for ast::RecordField {
+    fn short_label(&self) -> Option<String> {
+        short_label_from_ty(self, self.ty(), "")
+    }
+}
+
+impl ShortLabel for ast::Variant {
+    fn short_label(&self) -> Option<String> {
+        Some(self.name()?.text().to_string())
+    }
+}
+
+fn short_label_from_ty<T>(node: &T, ty: Option<ast::Type>, prefix: &str) -> Option<String>
+where
+    T: NameOwner + VisibilityOwner,
+{
+    let mut buf = short_label_from_node(node, prefix)?;
+
+    if let Some(type_ref) = ty {
+        format_to!(buf, ": {}", type_ref.syntax());
+    }
+
+    Some(buf)
+}
+
+fn short_label_from_node<T>(node: &T, label: &str) -> Option<String>
+where
+    T: NameOwner + VisibilityOwner,
+{
+    let mut buf = node.visibility().map(|v| format!("{} ", v.syntax())).unwrap_or_default();
+    buf.push_str(label);
+    buf.push_str(node.name()?.text().as_str());
+    Some(buf)
+}
diff --git a/crates/ide/src/expand_macro.rs b/crates/ide/src/expand_macro.rs
new file mode 100644
index 000000000..8a285bcf7
--- /dev/null
+++ b/crates/ide/src/expand_macro.rs
@@ -0,0 +1,283 @@
+use hir::Semantics;
+use ide_db::RootDatabase;
+use syntax::{
+    algo::{find_node_at_offset, SyntaxRewriter},
+    ast, AstNode, NodeOrToken, SyntaxKind,
+    SyntaxKind::*,
+    SyntaxNode, WalkEvent, T,
+};
+
+use crate::FilePosition;
+
+pub struct ExpandedMacro {
+    pub name: String,
+    pub expansion: String,
+}
+
+// Feature: Expand Macro Recursively
+//
+// Shows the full macro expansion of the macro at current cursor.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Expand macro recursively**
+// |===
+pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<ExpandedMacro> {
+    let sema = Semantics::new(db);
+    let file = sema.parse(position.file_id);
+    let name_ref = find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset)?;
+    let mac = name_ref.syntax().ancestors().find_map(ast::MacroCall::cast)?;
+
+    let expanded = expand_macro_recur(&sema, &mac)?;
+
+    // FIXME:
+    // macro expansion may lose all white space information
+    // But we hope someday we can use ra_fmt for that
+    let expansion = insert_whitespaces(expanded);
+    Some(ExpandedMacro { name: name_ref.text().to_string(), expansion })
+}
+
+fn expand_macro_recur(
+    sema: &Semantics<RootDatabase>,
+    macro_call: &ast::MacroCall,
+) -> Option<SyntaxNode> {
+    let mut expanded = sema.expand(macro_call)?;
+
+    let children = expanded.descendants().filter_map(ast::MacroCall::cast);
+    let mut rewriter = SyntaxRewriter::default();
+
+    for child in children.into_iter() {
+        if let Some(new_node) = expand_macro_recur(sema, &child) {
+            // Replace the whole node if it is root
+            // `replace_descendants` will not replace the parent node
+            // but `SyntaxNode::descendants include itself
+            if expanded == *child.syntax() {
+                expanded = new_node;
+            } else {
+                rewriter.replace(child.syntax(), &new_node)
+            }
+        }
+    }
+
+    let res = rewriter.rewrite(&expanded);
+    Some(res)
+}
+
+// FIXME: It would also be cool to share logic here and in the mbe tests,
+// which are pretty unreadable at the moment.
+fn insert_whitespaces(syn: SyntaxNode) -> String {
+    let mut res = String::new();
+    let mut token_iter = syn
+        .preorder_with_tokens()
+        .filter_map(|event| {
+            if let WalkEvent::Enter(NodeOrToken::Token(token)) = event {
+                Some(token)
+            } else {
+                None
+            }
+        })
+        .peekable();
+
+    let mut indent = 0;
+    let mut last: Option<SyntaxKind> = None;
+
+    while let Some(token) = token_iter.next() {
+        let mut is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
+            token_iter.peek().map(|it| f(it.kind())).unwrap_or(default)
+        };
+        let is_last =
+            |f: fn(SyntaxKind) -> bool, default| -> bool { last.map(f).unwrap_or(default) };
+
+        res += &match token.kind() {
+            k if is_text(k) && is_next(|it| !it.is_punct(), true) => token.text().to_string() + " ",
+            L_CURLY if is_next(|it| it != R_CURLY, true) => {
+                indent += 1;
+                let leading_space = if is_last(is_text, false) { " " } else { "" };
+                format!("{}{{\n{}", leading_space, "  ".repeat(indent))
+            }
+            R_CURLY if is_last(|it| it != L_CURLY, true) => {
+                indent = indent.saturating_sub(1);
+                format!("\n{}}}", "  ".repeat(indent))
+            }
+            R_CURLY => format!("}}\n{}", "  ".repeat(indent)),
+            T![;] => format!(";\n{}", "  ".repeat(indent)),
+            T![->] => " -> ".to_string(),
+            T![=] => " = ".to_string(),
+            T![=>] => " => ".to_string(),
+            _ => token.text().to_string(),
+        };
+
+        last = Some(token.kind());
+    }
+
+    return res;
+
+    fn is_text(k: SyntaxKind) -> bool {
+        k.is_keyword() || k.is_literal() || k == IDENT
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::mock_analysis::analysis_and_position;
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let (analysis, pos) = analysis_and_position(ra_fixture);
+        let expansion = analysis.expand_macro(pos).unwrap().unwrap();
+        let actual = format!("{}\n{}", expansion.name, expansion.expansion);
+        expect.assert_eq(&actual);
+    }
+
+    #[test]
+    fn macro_expand_recursive_expansion() {
+        check(
+            r#"
+macro_rules! bar {
+    () => { fn  b() {} }
+}
+macro_rules! foo {
+    () => { bar!(); }
+}
+macro_rules! baz {
+    () => { foo!(); }
+}
+f<|>oo!();
+"#,
+            expect![[r#"
+                foo
+                fn b(){}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_multiple_lines() {
+        check(
+            r#"
+macro_rules! foo {
+    () => {
+        fn some_thing() -> u32 {
+            let a = 0;
+            a + 10
+        }
+    }
+}
+f<|>oo!();
+        "#,
+            expect![[r#"
+            foo
+            fn some_thing() -> u32 {
+              let a = 0;
+              a+10
+            }"#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_match_ast() {
+        check(
+            r#"
+macro_rules! match_ast {
+    (match $node:ident { $($tt:tt)* }) => { match_ast!(match ($node) { $($tt)* }) };
+    (match ($node:expr) {
+        $( ast::$ast:ident($it:ident) => $res:block, )*
+        _ => $catch_all:expr $(,)?
+    }) => {{
+        $( if let Some($it) = ast::$ast::cast($node.clone()) $res else )*
+        { $catch_all }
+    }};
+}
+
+fn main() {
+    mat<|>ch_ast! {
+        match container {
+            ast::TraitDef(it) => {},
+            ast::ImplDef(it) => {},
+            _ => { continue },
+        }
+    }
+}
+"#,
+            expect![[r#"
+       match_ast
+       {
+         if let Some(it) = ast::TraitDef::cast(container.clone()){}
+         else if let Some(it) = ast::ImplDef::cast(container.clone()){}
+         else {
+           {
+             continue
+           }
+         }
+       }"#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_match_ast_inside_let_statement() {
+        check(
+            r#"
+macro_rules! match_ast {
+    (match $node:ident { $($tt:tt)* }) => { match_ast!(match ($node) { $($tt)* }) };
+    (match ($node:expr) {}) => {{}};
+}
+
+fn main() {
+    let p = f(|it| {
+        let res = mat<|>ch_ast! { match c {}};
+        Some(res)
+    })?;
+}
+"#,
+            expect![[r#"
+                match_ast
+                {}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_inner_macro_fail_to_expand() {
+        check(
+            r#"
+macro_rules! bar {
+    (BAD) => {};
+}
+macro_rules! foo {
+    () => {bar!()};
+}
+
+fn main() {
+    let res = fo<|>o!();
+}
+"#,
+            expect![[r#"
+                foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_with_dollar_crate() {
+        check(
+            r#"
+#[macro_export]
+macro_rules! bar {
+    () => {0};
+}
+macro_rules! foo {
+    () => {$crate::bar!()};
+}
+
+fn main() {
+    let res = fo<|>o!();
+}
+"#,
+            expect![[r#"
+                foo
+                0 "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/extend_selection.rs b/crates/ide/src/extend_selection.rs
new file mode 100644
index 000000000..34563a026
--- /dev/null
+++ b/crates/ide/src/extend_selection.rs
@@ -0,0 +1,654 @@
+use std::iter::successors;
+
+use hir::Semantics;
+use ide_db::RootDatabase;
+use syntax::{
+    algo::{self, find_covering_element, skip_trivia_token},
+    ast::{self, AstNode, AstToken},
+    Direction, NodeOrToken,
+    SyntaxKind::{self, *},
+    SyntaxNode, SyntaxToken, TextRange, TextSize, TokenAtOffset, T,
+};
+
+use crate::FileRange;
+
+// Feature: Extend Selection
+//
+// Extends the current selection to the encompassing syntactic construct
+// (expression, statement, item, module, etc). It works with multiple cursors.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+Shift+→]
+// |===
+pub(crate) fn extend_selection(db: &RootDatabase, frange: FileRange) -> TextRange {
+    let sema = Semantics::new(db);
+    let src = sema.parse(frange.file_id);
+    try_extend_selection(&sema, src.syntax(), frange).unwrap_or(frange.range)
+}
+
+fn try_extend_selection(
+    sema: &Semantics<RootDatabase>,
+    root: &SyntaxNode,
+    frange: FileRange,
+) -> Option<TextRange> {
+    let range = frange.range;
+
+    let string_kinds = [COMMENT, STRING, RAW_STRING, BYTE_STRING, RAW_BYTE_STRING];
+    let list_kinds = [
+        RECORD_PAT_FIELD_LIST,
+        MATCH_ARM_LIST,
+        RECORD_FIELD_LIST,
+        TUPLE_FIELD_LIST,
+        RECORD_EXPR_FIELD_LIST,
+        VARIANT_LIST,
+        USE_TREE_LIST,
+        GENERIC_PARAM_LIST,
+        GENERIC_ARG_LIST,
+        TYPE_BOUND_LIST,
+        PARAM_LIST,
+        ARG_LIST,
+        ARRAY_EXPR,
+        TUPLE_EXPR,
+        TUPLE_TYPE,
+        TUPLE_PAT,
+        WHERE_CLAUSE,
+    ];
+
+    if range.is_empty() {
+        let offset = range.start();
+        let mut leaves = root.token_at_offset(offset);
+        if leaves.clone().all(|it| it.kind() == WHITESPACE) {
+            return Some(extend_ws(root, leaves.next()?, offset));
+        }
+        let leaf_range = match leaves {
+            TokenAtOffset::None => return None,
+            TokenAtOffset::Single(l) => {
+                if string_kinds.contains(&l.kind()) {
+                    extend_single_word_in_comment_or_string(&l, offset)
+                        .unwrap_or_else(|| l.text_range())
+                } else {
+                    l.text_range()
+                }
+            }
+            TokenAtOffset::Between(l, r) => pick_best(l, r).text_range(),
+        };
+        return Some(leaf_range);
+    };
+    let node = match find_covering_element(root, range) {
+        NodeOrToken::Token(token) => {
+            if token.text_range() != range {
+                return Some(token.text_range());
+            }
+            if let Some(comment) = ast::Comment::cast(token.clone()) {
+                if let Some(range) = extend_comments(comment) {
+                    return Some(range);
+                }
+            }
+            token.parent()
+        }
+        NodeOrToken::Node(node) => node,
+    };
+
+    // if we are in single token_tree, we maybe live in macro or attr
+    if node.kind() == TOKEN_TREE {
+        if let Some(macro_call) = node.ancestors().find_map(ast::MacroCall::cast) {
+            if let Some(range) = extend_tokens_from_range(sema, macro_call, range) {
+                return Some(range);
+            }
+        }
+    }
+
+    if node.text_range() != range {
+        return Some(node.text_range());
+    }
+
+    let node = shallowest_node(&node);
+
+    if node.parent().map(|n| list_kinds.contains(&n.kind())) == Some(true) {
+        if let Some(range) = extend_list_item(&node) {
+            return Some(range);
+        }
+    }
+
+    node.parent().map(|it| it.text_range())
+}
+
+fn extend_tokens_from_range(
+    sema: &Semantics<RootDatabase>,
+    macro_call: ast::MacroCall,
+    original_range: TextRange,
+) -> Option<TextRange> {
+    let src = find_covering_element(&macro_call.syntax(), original_range);
+    let (first_token, last_token) = match src {
+        NodeOrToken::Node(it) => (it.first_token()?, it.last_token()?),
+        NodeOrToken::Token(it) => (it.clone(), it),
+    };
+
+    let mut first_token = skip_trivia_token(first_token, Direction::Next)?;
+    let mut last_token = skip_trivia_token(last_token, Direction::Prev)?;
+
+    while !original_range.contains_range(first_token.text_range()) {
+        first_token = skip_trivia_token(first_token.next_token()?, Direction::Next)?;
+    }
+    while !original_range.contains_range(last_token.text_range()) {
+        last_token = skip_trivia_token(last_token.prev_token()?, Direction::Prev)?;
+    }
+
+    // compute original mapped token range
+    let extended = {
+        let fst_expanded = sema.descend_into_macros(first_token.clone());
+        let lst_expanded = sema.descend_into_macros(last_token.clone());
+        let mut lca = algo::least_common_ancestor(&fst_expanded.parent(), &lst_expanded.parent())?;
+        lca = shallowest_node(&lca);
+        if lca.first_token() == Some(fst_expanded) && lca.last_token() == Some(lst_expanded) {
+            lca = lca.parent()?;
+        }
+        lca
+    };
+
+    // Compute parent node range
+    let validate = |token: &SyntaxToken| {
+        let expanded = sema.descend_into_macros(token.clone());
+        algo::least_common_ancestor(&extended, &expanded.parent()).as_ref() == Some(&extended)
+    };
+
+    // Find the first and last text range under expanded parent
+    let first = successors(Some(first_token), |token| {
+        let token = token.prev_token()?;
+        skip_trivia_token(token, Direction::Prev)
+    })
+    .take_while(validate)
+    .last()?;
+
+    let last = successors(Some(last_token), |token| {
+        let token = token.next_token()?;
+        skip_trivia_token(token, Direction::Next)
+    })
+    .take_while(validate)
+    .last()?;
+
+    let range = first.text_range().cover(last.text_range());
+    if range.contains_range(original_range) && original_range != range {
+        Some(range)
+    } else {
+        None
+    }
+}
+
+/// Find the shallowest node with same range, which allows us to traverse siblings.
+fn shallowest_node(node: &SyntaxNode) -> SyntaxNode {
+    node.ancestors().take_while(|n| n.text_range() == node.text_range()).last().unwrap()
+}
+
+fn extend_single_word_in_comment_or_string(
+    leaf: &SyntaxToken,
+    offset: TextSize,
+) -> Option<TextRange> {
+    let text: &str = leaf.text();
+    let cursor_position: u32 = (offset - leaf.text_range().start()).into();
+
+    let (before, after) = text.split_at(cursor_position as usize);
+
+    fn non_word_char(c: char) -> bool {
+        !(c.is_alphanumeric() || c == '_')
+    }
+
+    let start_idx = before.rfind(non_word_char)? as u32;
+    let end_idx = after.find(non_word_char).unwrap_or_else(|| after.len()) as u32;
+
+    let from: TextSize = (start_idx + 1).into();
+    let to: TextSize = (cursor_position + end_idx).into();
+
+    let range = TextRange::new(from, to);
+    if range.is_empty() {
+        None
+    } else {
+        Some(range + leaf.text_range().start())
+    }
+}
+
+fn extend_ws(root: &SyntaxNode, ws: SyntaxToken, offset: TextSize) -> TextRange {
+    let ws_text = ws.text();
+    let suffix = TextRange::new(offset, ws.text_range().end()) - ws.text_range().start();
+    let prefix = TextRange::new(ws.text_range().start(), offset) - ws.text_range().start();
+    let ws_suffix = &ws_text.as_str()[suffix];
+    let ws_prefix = &ws_text.as_str()[prefix];
+    if ws_text.contains('\n') && !ws_suffix.contains('\n') {
+        if let Some(node) = ws.next_sibling_or_token() {
+            let start = match ws_prefix.rfind('\n') {
+                Some(idx) => ws.text_range().start() + TextSize::from((idx + 1) as u32),
+                None => node.text_range().start(),
+            };
+            let end = if root.text().char_at(node.text_range().end()) == Some('\n') {
+                node.text_range().end() + TextSize::of('\n')
+            } else {
+                node.text_range().end()
+            };
+            return TextRange::new(start, end);
+        }
+    }
+    ws.text_range()
+}
+
+fn pick_best(l: SyntaxToken, r: SyntaxToken) -> SyntaxToken {
+    return if priority(&r) > priority(&l) { r } else { l };
+    fn priority(n: &SyntaxToken) -> usize {
+        match n.kind() {
+            WHITESPACE => 0,
+            IDENT | T![self] | T![super] | T![crate] | LIFETIME => 2,
+            _ => 1,
+        }
+    }
+}
+
+/// Extend list item selection to include nearby delimiter and whitespace.
+fn extend_list_item(node: &SyntaxNode) -> Option<TextRange> {
+    fn is_single_line_ws(node: &SyntaxToken) -> bool {
+        node.kind() == WHITESPACE && !node.text().contains('\n')
+    }
+
+    fn nearby_delimiter(
+        delimiter_kind: SyntaxKind,
+        node: &SyntaxNode,
+        dir: Direction,
+    ) -> Option<SyntaxToken> {
+        node.siblings_with_tokens(dir)
+            .skip(1)
+            .skip_while(|node| match node {
+                NodeOrToken::Node(_) => false,
+                NodeOrToken::Token(it) => is_single_line_ws(it),
+            })
+            .next()
+            .and_then(|it| it.into_token())
+            .filter(|node| node.kind() == delimiter_kind)
+    }
+
+    let delimiter = match node.kind() {
+        TYPE_BOUND => T![+],
+        _ => T![,],
+    };
+
+    if let Some(delimiter_node) = nearby_delimiter(delimiter, node, Direction::Next) {
+        // Include any following whitespace when delimiter is after list item.
+        let final_node = delimiter_node
+            .next_sibling_or_token()
+            .and_then(|it| it.into_token())
+            .filter(|node| is_single_line_ws(node))
+            .unwrap_or(delimiter_node);
+
+        return Some(TextRange::new(node.text_range().start(), final_node.text_range().end()));
+    }
+    if let Some(delimiter_node) = nearby_delimiter(delimiter, node, Direction::Prev) {
+        return Some(TextRange::new(delimiter_node.text_range().start(), node.text_range().end()));
+    }
+
+    None
+}
+
+fn extend_comments(comment: ast::Comment) -> Option<TextRange> {
+    let prev = adj_comments(&comment, Direction::Prev);
+    let next = adj_comments(&comment, Direction::Next);
+    if prev != next {
+        Some(TextRange::new(prev.syntax().text_range().start(), next.syntax().text_range().end()))
+    } else {
+        None
+    }
+}
+
+fn adj_comments(comment: &ast::Comment, dir: Direction) -> ast::Comment {
+    let mut res = comment.clone();
+    for element in comment.syntax().siblings_with_tokens(dir) {
+        let token = match element.as_token() {
+            None => break,
+            Some(token) => token,
+        };
+        if let Some(c) = ast::Comment::cast(token.clone()) {
+            res = c
+        } else if token.kind() != WHITESPACE || token.text().contains("\n\n") {
+            break;
+        }
+    }
+    res
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::mock_analysis::analysis_and_position;
+
+    use super::*;
+
+    fn do_check(before: &str, afters: &[&str]) {
+        let (analysis, position) = analysis_and_position(&before);
+        let before = analysis.file_text(position.file_id).unwrap();
+        let range = TextRange::empty(position.offset);
+        let mut frange = FileRange { file_id: position.file_id, range };
+
+        for &after in afters {
+            frange.range = analysis.extend_selection(frange).unwrap();
+            let actual = &before[frange.range];
+            assert_eq!(after, actual);
+        }
+    }
+
+    #[test]
+    fn test_extend_selection_arith() {
+        do_check(r#"fn foo() { <|>1 + 1 }"#, &["1", "1 + 1", "{ 1 + 1 }"]);
+    }
+
+    #[test]
+    fn test_extend_selection_list() {
+        do_check(r#"fn foo(<|>x: i32) {}"#, &["x", "x: i32"]);
+        do_check(r#"fn foo(<|>x: i32, y: i32) {}"#, &["x", "x: i32", "x: i32, "]);
+        do_check(r#"fn foo(<|>x: i32,y: i32) {}"#, &["x", "x: i32", "x: i32,", "(x: i32,y: i32)"]);
+        do_check(r#"fn foo(x: i32, <|>y: i32) {}"#, &["y", "y: i32", ", y: i32"]);
+        do_check(r#"fn foo(x: i32, <|>y: i32, ) {}"#, &["y", "y: i32", "y: i32, "]);
+        do_check(r#"fn foo(x: i32,<|>y: i32) {}"#, &["y", "y: i32", ",y: i32"]);
+
+        do_check(r#"const FOO: [usize; 2] = [ 22<|> , 33];"#, &["22", "22 , "]);
+        do_check(r#"const FOO: [usize; 2] = [ 22 , 33<|>];"#, &["33", ", 33"]);
+        do_check(r#"const FOO: [usize; 2] = [ 22 , 33<|> ,];"#, &["33", "33 ,", "[ 22 , 33 ,]"]);
+
+        do_check(r#"fn main() { (1, 2<|>) }"#, &["2", ", 2", "(1, 2)"]);
+
+        do_check(
+            r#"
+const FOO: [usize; 2] = [
+    22,
+    <|>33,
+]"#,
+            &["33", "33,"],
+        );
+
+        do_check(
+            r#"
+const FOO: [usize; 2] = [
+    22
+    , 33<|>,
+]"#,
+            &["33", "33,"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_start_of_the_line() {
+        do_check(
+            r#"
+impl S {
+<|>    fn foo() {
+
+    }
+}"#,
+            &["    fn foo() {\n\n    }\n"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_doc_comments() {
+        do_check(
+            r#"
+struct A;
+
+/// bla
+/// bla
+struct B {
+    <|>
+}
+            "#,
+            &["\n    \n", "{\n    \n}", "/// bla\n/// bla\nstruct B {\n    \n}"],
+        )
+    }
+
+    #[test]
+    fn test_extend_selection_comments() {
+        do_check(
+            r#"
+fn bar(){}
+
+// fn foo() {
+// 1 + <|>1
+// }
+
+// fn foo(){}
+    "#,
+            &["1", "// 1 + 1", "// fn foo() {\n// 1 + 1\n// }"],
+        );
+
+        do_check(
+            r#"
+// #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+// pub enum Direction {
+//  <|>   Next,
+//     Prev
+// }
+"#,
+            &[
+                "//     Next,",
+                "// #[derive(Debug, Clone, Copy, PartialEq, Eq)]\n// pub enum Direction {\n//     Next,\n//     Prev\n// }",
+            ],
+        );
+
+        do_check(
+            r#"
+/*
+foo
+_bar1<|>*/
+"#,
+            &["_bar1", "/*\nfoo\n_bar1*/"],
+        );
+
+        do_check(r#"//!<|>foo_2 bar"#, &["foo_2", "//!foo_2 bar"]);
+
+        do_check(r#"/<|>/foo bar"#, &["//foo bar"]);
+    }
+
+    #[test]
+    fn test_extend_selection_prefer_idents() {
+        do_check(
+            r#"
+fn main() { foo<|>+bar;}
+"#,
+            &["foo", "foo+bar"],
+        );
+        do_check(
+            r#"
+fn main() { foo+<|>bar;}
+"#,
+            &["bar", "foo+bar"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_prefer_lifetimes() {
+        do_check(r#"fn foo<<|>'a>() {}"#, &["'a", "<'a>"]);
+        do_check(r#"fn foo<'a<|>>() {}"#, &["'a", "<'a>"]);
+    }
+
+    #[test]
+    fn test_extend_selection_select_first_word() {
+        do_check(r#"// foo bar b<|>az quxx"#, &["baz", "// foo bar baz quxx"]);
+        do_check(
+            r#"
+impl S {
+fn foo() {
+// hel<|>lo world
+}
+}
+"#,
+            &["hello", "// hello world"],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_string() {
+        do_check(
+            r#"
+fn bar(){}
+
+" fn f<|>oo() {"
+"#,
+            &["foo", "\" fn foo() {\""],
+        );
+    }
+
+    #[test]
+    fn test_extend_trait_bounds_list_in_where_clause() {
+        do_check(
+            r#"
+fn foo<R>()
+    where
+        R: req::Request + 'static,
+        R::Params: DeserializeOwned<|> + panic::UnwindSafe + 'static,
+        R::Result: Serialize + 'static,
+"#,
+            &[
+                "DeserializeOwned",
+                "DeserializeOwned + ",
+                "DeserializeOwned + panic::UnwindSafe + 'static",
+                "R::Params: DeserializeOwned + panic::UnwindSafe + 'static",
+                "R::Params: DeserializeOwned + panic::UnwindSafe + 'static,",
+            ],
+        );
+        do_check(r#"fn foo<T>() where T: <|>Copy"#, &["Copy"]);
+        do_check(r#"fn foo<T>() where T: <|>Copy + Display"#, &["Copy", "Copy + "]);
+        do_check(r#"fn foo<T>() where T: <|>Copy +Display"#, &["Copy", "Copy +"]);
+        do_check(r#"fn foo<T>() where T: <|>Copy+Display"#, &["Copy", "Copy+"]);
+        do_check(r#"fn foo<T>() where T: Copy + <|>Display"#, &["Display", "+ Display"]);
+        do_check(r#"fn foo<T>() where T: Copy + <|>Display + Sync"#, &["Display", "Display + "]);
+        do_check(r#"fn foo<T>() where T: Copy +<|>Display"#, &["Display", "+Display"]);
+    }
+
+    #[test]
+    fn test_extend_trait_bounds_list_inline() {
+        do_check(r#"fn foo<T: <|>Copy>() {}"#, &["Copy"]);
+        do_check(r#"fn foo<T: <|>Copy + Display>() {}"#, &["Copy", "Copy + "]);
+        do_check(r#"fn foo<T: <|>Copy +Display>() {}"#, &["Copy", "Copy +"]);
+        do_check(r#"fn foo<T: <|>Copy+Display>() {}"#, &["Copy", "Copy+"]);
+        do_check(r#"fn foo<T: Copy + <|>Display>() {}"#, &["Display", "+ Display"]);
+        do_check(r#"fn foo<T: Copy + <|>Display + Sync>() {}"#, &["Display", "Display + "]);
+        do_check(r#"fn foo<T: Copy +<|>Display>() {}"#, &["Display", "+Display"]);
+        do_check(
+            r#"fn foo<T: Copy<|> + Display, U: Copy>() {}"#,
+            &[
+                "Copy",
+                "Copy + ",
+                "Copy + Display",
+                "T: Copy + Display",
+                "T: Copy + Display, ",
+                "<T: Copy + Display, U: Copy>",
+            ],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_on_tuple_in_type() {
+        do_check(
+            r#"fn main() { let _: (krate, <|>_crate_def_map, module_id) = (); }"#,
+            &["_crate_def_map", "_crate_def_map, ", "(krate, _crate_def_map, module_id)"],
+        );
+        // white space variations
+        do_check(
+            r#"fn main() { let _: (krate,<|>_crate_def_map,module_id) = (); }"#,
+            &["_crate_def_map", "_crate_def_map,", "(krate,_crate_def_map,module_id)"],
+        );
+        do_check(
+            r#"
+fn main() { let _: (
+    krate,
+    _crate<|>_def_map,
+    module_id
+) = (); }"#,
+            &[
+                "_crate_def_map",
+                "_crate_def_map,",
+                "(\n    krate,\n    _crate_def_map,\n    module_id\n)",
+            ],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_on_tuple_in_rvalue() {
+        do_check(
+            r#"fn main() { let var = (krate, _crate_def_map<|>, module_id); }"#,
+            &["_crate_def_map", "_crate_def_map, ", "(krate, _crate_def_map, module_id)"],
+        );
+        // white space variations
+        do_check(
+            r#"fn main() { let var = (krate,_crate<|>_def_map,module_id); }"#,
+            &["_crate_def_map", "_crate_def_map,", "(krate,_crate_def_map,module_id)"],
+        );
+        do_check(
+            r#"
+fn main() { let var = (
+    krate,
+    _crate_def_map<|>,
+    module_id
+); }"#,
+            &[
+                "_crate_def_map",
+                "_crate_def_map,",
+                "(\n    krate,\n    _crate_def_map,\n    module_id\n)",
+            ],
+        );
+    }
+
+    #[test]
+    fn test_extend_selection_on_tuple_pat() {
+        do_check(
+            r#"fn main() { let (krate, _crate_def_map<|>, module_id) = var; }"#,
+            &["_crate_def_map", "_crate_def_map, ", "(krate, _crate_def_map, module_id)"],
+        );
+        // white space variations
+        do_check(
+            r#"fn main() { let (krate,_crate<|>_def_map,module_id) = var; }"#,
+            &["_crate_def_map", "_crate_def_map,", "(krate,_crate_def_map,module_id)"],
+        );
+        do_check(
+            r#"
+fn main() { let (
+    krate,
+    _crate_def_map<|>,
+    module_id
+) = var; }"#,
+            &[
+                "_crate_def_map",
+                "_crate_def_map,",
+                "(\n    krate,\n    _crate_def_map,\n    module_id\n)",
+            ],
+        );
+    }
+
+    #[test]
+    fn extend_selection_inside_macros() {
+        do_check(
+            r#"macro_rules! foo { ($item:item) => {$item} }
+                foo!{fn hello(na<|>me:usize){}}"#,
+            &[
+                "name",
+                "name:usize",
+                "(name:usize)",
+                "fn hello(name:usize){}",
+                "{fn hello(name:usize){}}",
+                "foo!{fn hello(name:usize){}}",
+            ],
+        );
+    }
+
+    #[test]
+    fn extend_selection_inside_recur_macros() {
+        do_check(
+            r#" macro_rules! foo2 { ($item:item) => {$item} }
+                macro_rules! foo { ($item:item) => {foo2!($item);} }
+                foo!{fn hello(na<|>me:usize){}}"#,
+            &[
+                "name",
+                "name:usize",
+                "(name:usize)",
+                "fn hello(name:usize){}",
+                "{fn hello(name:usize){}}",
+                "foo!{fn hello(name:usize){}}",
+            ],
+        );
+    }
+}
diff --git a/crates/ide/src/file_structure.rs b/crates/ide/src/file_structure.rs
new file mode 100644
index 000000000..6168fb837
--- /dev/null
+++ b/crates/ide/src/file_structure.rs
@@ -0,0 +1,431 @@
+use syntax::{
+    ast::{self, AttrsOwner, GenericParamsOwner, NameOwner},
+    match_ast, AstNode, SourceFile, SyntaxKind, SyntaxNode, TextRange, WalkEvent,
+};
+
+#[derive(Debug, Clone)]
+pub struct StructureNode {
+    pub parent: Option<usize>,
+    pub label: String,
+    pub navigation_range: TextRange,
+    pub node_range: TextRange,
+    pub kind: SyntaxKind,
+    pub detail: Option<String>,
+    pub deprecated: bool,
+}
+
+// Feature: File Structure
+//
+// Provides a tree of the symbols defined in the file. Can be used to
+//
+// * fuzzy search symbol in a file (super useful)
+// * draw breadcrumbs to describe the context around the cursor
+// * draw outline of the file
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+Shift+O]
+// |===
+pub fn file_structure(file: &SourceFile) -> Vec<StructureNode> {
+    let mut res = Vec::new();
+    let mut stack = Vec::new();
+
+    for event in file.syntax().preorder() {
+        match event {
+            WalkEvent::Enter(node) => {
+                if let Some(mut symbol) = structure_node(&node) {
+                    symbol.parent = stack.last().copied();
+                    stack.push(res.len());
+                    res.push(symbol);
+                }
+            }
+            WalkEvent::Leave(node) => {
+                if structure_node(&node).is_some() {
+                    stack.pop().unwrap();
+                }
+            }
+        }
+    }
+    res
+}
+
+fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
+    fn decl<N: NameOwner + AttrsOwner>(node: N) -> Option<StructureNode> {
+        decl_with_detail(&node, None)
+    }
+
+    fn decl_with_type_ref<N: NameOwner + AttrsOwner>(
+        node: &N,
+        type_ref: Option<ast::Type>,
+    ) -> Option<StructureNode> {
+        let detail = type_ref.map(|type_ref| {
+            let mut detail = String::new();
+            collapse_ws(type_ref.syntax(), &mut detail);
+            detail
+        });
+        decl_with_detail(node, detail)
+    }
+
+    fn decl_with_detail<N: NameOwner + AttrsOwner>(
+        node: &N,
+        detail: Option<String>,
+    ) -> Option<StructureNode> {
+        let name = node.name()?;
+
+        Some(StructureNode {
+            parent: None,
+            label: name.text().to_string(),
+            navigation_range: name.syntax().text_range(),
+            node_range: node.syntax().text_range(),
+            kind: node.syntax().kind(),
+            detail,
+            deprecated: node.attrs().filter_map(|x| x.simple_name()).any(|x| x == "deprecated"),
+        })
+    }
+
+    fn collapse_ws(node: &SyntaxNode, output: &mut String) {
+        let mut can_insert_ws = false;
+        node.text().for_each_chunk(|chunk| {
+            for line in chunk.lines() {
+                let line = line.trim();
+                if line.is_empty() {
+                    if can_insert_ws {
+                        output.push(' ');
+                        can_insert_ws = false;
+                    }
+                } else {
+                    output.push_str(line);
+                    can_insert_ws = true;
+                }
+            }
+        })
+    }
+
+    match_ast! {
+        match node {
+            ast::Fn(it) => {
+                let mut detail = String::from("fn");
+                if let Some(type_param_list) = it.generic_param_list() {
+                    collapse_ws(type_param_list.syntax(), &mut detail);
+                }
+                if let Some(param_list) = it.param_list() {
+                    collapse_ws(param_list.syntax(), &mut detail);
+                }
+                if let Some(ret_type) = it.ret_type() {
+                    detail.push_str(" ");
+                    collapse_ws(ret_type.syntax(), &mut detail);
+                }
+
+                decl_with_detail(&it, Some(detail))
+            },
+            ast::Struct(it) => decl(it),
+            ast::Union(it) => decl(it),
+            ast::Enum(it) => decl(it),
+            ast::Variant(it) => decl(it),
+            ast::Trait(it) => decl(it),
+            ast::Module(it) => decl(it),
+            ast::TypeAlias(it) => decl_with_type_ref(&it, it.ty()),
+            ast::RecordField(it) => decl_with_type_ref(&it, it.ty()),
+            ast::Const(it) => decl_with_type_ref(&it, it.ty()),
+            ast::Static(it) => decl_with_type_ref(&it, it.ty()),
+            ast::Impl(it) => {
+                let target_type = it.self_ty()?;
+                let target_trait = it.trait_();
+                let label = match target_trait {
+                    None => format!("impl {}", target_type.syntax().text()),
+                    Some(t) => {
+                        format!("impl {} for {}", t.syntax().text(), target_type.syntax().text(),)
+                    }
+                };
+
+                let node = StructureNode {
+                    parent: None,
+                    label,
+                    navigation_range: target_type.syntax().text_range(),
+                    node_range: it.syntax().text_range(),
+                    kind: it.syntax().kind(),
+                    detail: None,
+                    deprecated: false,
+                };
+                Some(node)
+            },
+            ast::MacroCall(it) => {
+                match it.path().and_then(|it| it.segment()).and_then(|it| it.name_ref()) {
+                    Some(path_segment) if path_segment.text() == "macro_rules"
+                    => decl(it),
+                    _ => None,
+                }
+            },
+            _ => None,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use super::*;
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let file = SourceFile::parse(ra_fixture).ok().unwrap();
+        let structure = file_structure(&file);
+        expect.assert_debug_eq(&structure)
+    }
+
+    #[test]
+    fn test_file_structure() {
+        check(
+            r#"
+struct Foo {
+    x: i32
+}
+
+mod m {
+    fn bar1() {}
+    fn bar2<T>(t: T) -> T {}
+    fn bar3<A,
+        B>(a: A,
+        b: B) -> Vec<
+        u32
+    > {}
+}
+
+enum E { X, Y(i32) }
+type T = ();
+static S: i32 = 92;
+const C: i32 = 92;
+
+impl E {}
+
+impl fmt::Debug for E {}
+
+macro_rules! mc {
+    () => {}
+}
+
+#[macro_export]
+macro_rules! mcexp {
+    () => {}
+}
+
+/// Doc comment
+macro_rules! mcexp {
+    () => {}
+}
+
+#[deprecated]
+fn obsolete() {}
+
+#[deprecated(note = "for awhile")]
+fn very_obsolete() {}
+"#,
+            expect![[r#"
+                [
+                    StructureNode {
+                        parent: None,
+                        label: "Foo",
+                        navigation_range: 8..11,
+                        node_range: 1..26,
+                        kind: STRUCT,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            0,
+                        ),
+                        label: "x",
+                        navigation_range: 18..19,
+                        node_range: 18..24,
+                        kind: RECORD_FIELD,
+                        detail: Some(
+                            "i32",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "m",
+                        navigation_range: 32..33,
+                        node_range: 28..158,
+                        kind: MODULE,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            2,
+                        ),
+                        label: "bar1",
+                        navigation_range: 43..47,
+                        node_range: 40..52,
+                        kind: FN,
+                        detail: Some(
+                            "fn()",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            2,
+                        ),
+                        label: "bar2",
+                        navigation_range: 60..64,
+                        node_range: 57..81,
+                        kind: FN,
+                        detail: Some(
+                            "fn<T>(t: T) -> T",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            2,
+                        ),
+                        label: "bar3",
+                        navigation_range: 89..93,
+                        node_range: 86..156,
+                        kind: FN,
+                        detail: Some(
+                            "fn<A, B>(a: A, b: B) -> Vec< u32 >",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "E",
+                        navigation_range: 165..166,
+                        node_range: 160..180,
+                        kind: ENUM,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            6,
+                        ),
+                        label: "X",
+                        navigation_range: 169..170,
+                        node_range: 169..170,
+                        kind: VARIANT,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            6,
+                        ),
+                        label: "Y",
+                        navigation_range: 172..173,
+                        node_range: 172..178,
+                        kind: VARIANT,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "T",
+                        navigation_range: 186..187,
+                        node_range: 181..193,
+                        kind: TYPE_ALIAS,
+                        detail: Some(
+                            "()",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "S",
+                        navigation_range: 201..202,
+                        node_range: 194..213,
+                        kind: STATIC,
+                        detail: Some(
+                            "i32",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "C",
+                        navigation_range: 220..221,
+                        node_range: 214..232,
+                        kind: CONST,
+                        detail: Some(
+                            "i32",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "impl E",
+                        navigation_range: 239..240,
+                        node_range: 234..243,
+                        kind: IMPL,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "impl fmt::Debug for E",
+                        navigation_range: 265..266,
+                        node_range: 245..269,
+                        kind: IMPL,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "mc",
+                        navigation_range: 284..286,
+                        node_range: 271..303,
+                        kind: MACRO_CALL,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "mcexp",
+                        navigation_range: 334..339,
+                        node_range: 305..356,
+                        kind: MACRO_CALL,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "mcexp",
+                        navigation_range: 387..392,
+                        node_range: 358..409,
+                        kind: MACRO_CALL,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "obsolete",
+                        navigation_range: 428..436,
+                        node_range: 411..441,
+                        kind: FN,
+                        detail: Some(
+                            "fn()",
+                        ),
+                        deprecated: true,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "very_obsolete",
+                        navigation_range: 481..494,
+                        node_range: 443..499,
+                        kind: FN,
+                        detail: Some(
+                            "fn()",
+                        ),
+                        deprecated: true,
+                    },
+                ]
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/folding_ranges.rs b/crates/ide/src/folding_ranges.rs
new file mode 100644
index 000000000..7523aec55
--- /dev/null
+++ b/crates/ide/src/folding_ranges.rs
@@ -0,0 +1,422 @@
+//! FIXME: write short doc here
+
+use rustc_hash::FxHashSet;
+
+use syntax::{
+    ast::{self, AstNode, AstToken, VisibilityOwner},
+    Direction, NodeOrToken, SourceFile,
+    SyntaxKind::{self, *},
+    SyntaxNode, TextRange,
+};
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum FoldKind {
+    Comment,
+    Imports,
+    Mods,
+    Block,
+    ArgList,
+}
+
+#[derive(Debug)]
+pub struct Fold {
+    pub range: TextRange,
+    pub kind: FoldKind,
+}
+
+pub(crate) fn folding_ranges(file: &SourceFile) -> Vec<Fold> {
+    let mut res = vec![];
+    let mut visited_comments = FxHashSet::default();
+    let mut visited_imports = FxHashSet::default();
+    let mut visited_mods = FxHashSet::default();
+
+    for element in file.syntax().descendants_with_tokens() {
+        // Fold items that span multiple lines
+        if let Some(kind) = fold_kind(element.kind()) {
+            let is_multiline = match &element {
+                NodeOrToken::Node(node) => node.text().contains_char('\n'),
+                NodeOrToken::Token(token) => token.text().contains('\n'),
+            };
+            if is_multiline {
+                res.push(Fold { range: element.text_range(), kind });
+                continue;
+            }
+        }
+
+        match element {
+            NodeOrToken::Token(token) => {
+                // Fold groups of comments
+                if let Some(comment) = ast::Comment::cast(token) {
+                    if !visited_comments.contains(&comment) {
+                        if let Some(range) =
+                            contiguous_range_for_comment(comment, &mut visited_comments)
+                        {
+                            res.push(Fold { range, kind: FoldKind::Comment })
+                        }
+                    }
+                }
+            }
+            NodeOrToken::Node(node) => {
+                // Fold groups of imports
+                if node.kind() == USE && !visited_imports.contains(&node) {
+                    if let Some(range) = contiguous_range_for_group(&node, &mut visited_imports) {
+                        res.push(Fold { range, kind: FoldKind::Imports })
+                    }
+                }
+
+                // Fold groups of mods
+                if node.kind() == MODULE && !has_visibility(&node) && !visited_mods.contains(&node)
+                {
+                    if let Some(range) =
+                        contiguous_range_for_group_unless(&node, has_visibility, &mut visited_mods)
+                    {
+                        res.push(Fold { range, kind: FoldKind::Mods })
+                    }
+                }
+            }
+        }
+    }
+
+    res
+}
+
+fn fold_kind(kind: SyntaxKind) -> Option<FoldKind> {
+    match kind {
+        COMMENT => Some(FoldKind::Comment),
+        USE => Some(FoldKind::Imports),
+        ARG_LIST | PARAM_LIST => Some(FoldKind::ArgList),
+        ASSOC_ITEM_LIST
+        | RECORD_FIELD_LIST
+        | RECORD_PAT_FIELD_LIST
+        | RECORD_EXPR_FIELD_LIST
+        | ITEM_LIST
+        | EXTERN_ITEM_LIST
+        | USE_TREE_LIST
+        | BLOCK_EXPR
+        | MATCH_ARM_LIST
+        | VARIANT_LIST
+        | TOKEN_TREE => Some(FoldKind::Block),
+        _ => None,
+    }
+}
+
+fn has_visibility(node: &SyntaxNode) -> bool {
+    ast::Module::cast(node.clone()).and_then(|m| m.visibility()).is_some()
+}
+
+fn contiguous_range_for_group(
+    first: &SyntaxNode,
+    visited: &mut FxHashSet<SyntaxNode>,
+) -> Option<TextRange> {
+    contiguous_range_for_group_unless(first, |_| false, visited)
+}
+
+fn contiguous_range_for_group_unless(
+    first: &SyntaxNode,
+    unless: impl Fn(&SyntaxNode) -> bool,
+    visited: &mut FxHashSet<SyntaxNode>,
+) -> Option<TextRange> {
+    visited.insert(first.clone());
+
+    let mut last = first.clone();
+    for element in first.siblings_with_tokens(Direction::Next) {
+        let node = match element {
+            NodeOrToken::Token(token) => {
+                if let Some(ws) = ast::Whitespace::cast(token) {
+                    if !ws.spans_multiple_lines() {
+                        // Ignore whitespace without blank lines
+                        continue;
+                    }
+                }
+                // There is a blank line or another token, which means that the
+                // group ends here
+                break;
+            }
+            NodeOrToken::Node(node) => node,
+        };
+
+        // Stop if we find a node that doesn't belong to the group
+        if node.kind() != first.kind() || unless(&node) {
+            break;
+        }
+
+        visited.insert(node.clone());
+        last = node;
+    }
+
+    if first != &last {
+        Some(TextRange::new(first.text_range().start(), last.text_range().end()))
+    } else {
+        // The group consists of only one element, therefore it cannot be folded
+        None
+    }
+}
+
+fn contiguous_range_for_comment(
+    first: ast::Comment,
+    visited: &mut FxHashSet<ast::Comment>,
+) -> Option<TextRange> {
+    visited.insert(first.clone());
+
+    // Only fold comments of the same flavor
+    let group_kind = first.kind();
+    if !group_kind.shape.is_line() {
+        return None;
+    }
+
+    let mut last = first.clone();
+    for element in first.syntax().siblings_with_tokens(Direction::Next) {
+        match element {
+            NodeOrToken::Token(token) => {
+                if let Some(ws) = ast::Whitespace::cast(token.clone()) {
+                    if !ws.spans_multiple_lines() {
+                        // Ignore whitespace without blank lines
+                        continue;
+                    }
+                }
+                if let Some(c) = ast::Comment::cast(token) {
+                    if c.kind() == group_kind {
+                        visited.insert(c.clone());
+                        last = c;
+                        continue;
+                    }
+                }
+                // The comment group ends because either:
+                // * An element of a different kind was reached
+                // * A comment of a different flavor was reached
+                break;
+            }
+            NodeOrToken::Node(_) => break,
+        };
+    }
+
+    if first != last {
+        Some(TextRange::new(first.syntax().text_range().start(), last.syntax().text_range().end()))
+    } else {
+        // The group consists of only one element, therefore it cannot be folded
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::extract_tags;
+
+    use super::*;
+
+    fn check(ra_fixture: &str) {
+        let (ranges, text) = extract_tags(ra_fixture, "fold");
+
+        let parse = SourceFile::parse(&text);
+        let folds = folding_ranges(&parse.tree());
+        assert_eq!(
+            folds.len(),
+            ranges.len(),
+            "The amount of folds is different than the expected amount"
+        );
+
+        for (fold, (range, attr)) in folds.iter().zip(ranges.into_iter()) {
+            assert_eq!(fold.range.start(), range.start());
+            assert_eq!(fold.range.end(), range.end());
+
+            let kind = match fold.kind {
+                FoldKind::Comment => "comment",
+                FoldKind::Imports => "imports",
+                FoldKind::Mods => "mods",
+                FoldKind::Block => "block",
+                FoldKind::ArgList => "arglist",
+            };
+            assert_eq!(kind, &attr.unwrap());
+        }
+    }
+
+    #[test]
+    fn test_fold_comments() {
+        check(
+            r#"
+<fold comment>// Hello
+// this is a multiline
+// comment
+//</fold>
+
+// But this is not
+
+fn main() <fold block>{
+    <fold comment>// We should
+    // also
+    // fold
+    // this one.</fold>
+    <fold comment>//! But this one is different
+    //! because it has another flavor</fold>
+    <fold comment>/* As does this
+    multiline comment */</fold>
+}</fold>"#,
+        );
+    }
+
+    #[test]
+    fn test_fold_imports() {
+        check(
+            r#"
+<fold imports>use std::<fold block>{
+    str,
+    vec,
+    io as iop
+}</fold>;</fold>
+
+fn main() <fold block>{
+}</fold>"#,
+        );
+    }
+
+    #[test]
+    fn test_fold_mods() {
+        check(
+            r#"
+
+pub mod foo;
+<fold mods>mod after_pub;
+mod after_pub_next;</fold>
+
+<fold mods>mod before_pub;
+mod before_pub_next;</fold>
+pub mod bar;
+
+mod not_folding_single;
+pub mod foobar;
+pub not_folding_single_next;
+
+<fold mods>#[cfg(test)]
+mod with_attribute;
+mod with_attribute_next;</fold>
+
+fn main() <fold block>{
+}</fold>"#,
+        );
+    }
+
+    #[test]
+    fn test_fold_import_groups() {
+        check(
+            r#"
+<fold imports>use std::str;
+use std::vec;
+use std::io as iop;</fold>
+
+<fold imports>use std::mem;
+use std::f64;</fold>
+
+use std::collections::HashMap;
+// Some random comment
+use std::collections::VecDeque;
+
+fn main() <fold block>{
+}</fold>"#,
+        );
+    }
+
+    #[test]
+    fn test_fold_import_and_groups() {
+        check(
+            r#"
+<fold imports>use std::str;
+use std::vec;
+use std::io as iop;</fold>
+
+<fold imports>use std::mem;
+use std::f64;</fold>
+
+<fold imports>use std::collections::<fold block>{
+    HashMap,
+    VecDeque,
+}</fold>;</fold>
+// Some random comment
+
+fn main() <fold block>{
+}</fold>"#,
+        );
+    }
+
+    #[test]
+    fn test_folds_structs() {
+        check(
+            r#"
+struct Foo <fold block>{
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
+    fn test_folds_traits() {
+        check(
+            r#"
+trait Foo <fold block>{
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
+    fn test_folds_macros() {
+        check(
+            r#"
+macro_rules! foo <fold block>{
+    ($($tt:tt)*) => { $($tt)* }
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fold_match_arms() {
+        check(
+            r#"
+fn main() <fold block>{
+    match 0 <fold block>{
+        0 => 0,
+        _ => 1,
+    }</fold>
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
+    fn fold_big_calls() {
+        check(
+            r#"
+fn main() <fold block>{
+    frobnicate<fold arglist>(
+        1,
+        2,
+        3,
+    )</fold>
+}</fold>
+"#,
+        )
+    }
+
+    #[test]
+    fn fold_record_literals() {
+        check(
+            r#"
+const _: S = S <fold block>{
+
+}</fold>;
+"#,
+        )
+    }
+
+    #[test]
+    fn fold_multiline_params() {
+        check(
+            r#"
+fn foo<fold arglist>(
+    x: i32,
+    y: String,
+)</fold> {}
+"#,
+        )
+    }
+}
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
new file mode 100644
index 000000000..15e9b7fad
--- /dev/null
+++ b/crates/ide/src/goto_definition.rs
@@ -0,0 +1,989 @@
+use hir::Semantics;
+use ide_db::{
+    defs::{classify_name, classify_name_ref},
+    symbol_index, RootDatabase,
+};
+use syntax::{
+    ast::{self},
+    match_ast, AstNode,
+    SyntaxKind::*,
+    SyntaxToken, TokenAtOffset, T,
+};
+
+use crate::{
+    display::{ToNav, TryToNav},
+    FilePosition, NavigationTarget, RangeInfo,
+};
+
+// Feature: Go to Definition
+//
+// Navigates to the definition of an identifier.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[F12]
+// |===
+pub(crate) fn goto_definition(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    let sema = Semantics::new(db);
+    let file = sema.parse(position.file_id).syntax().clone();
+    let original_token = pick_best(file.token_at_offset(position.offset))?;
+    let token = sema.descend_into_macros(original_token.clone());
+    let parent = token.parent();
+
+    let nav_targets = match_ast! {
+        match parent {
+            ast::NameRef(name_ref) => {
+                reference_definition(&sema, &name_ref).to_vec()
+            },
+            ast::Name(name) => {
+                let def = classify_name(&sema, &name)?.definition(sema.db);
+                let nav = def.try_to_nav(sema.db)?;
+                vec![nav]
+            },
+            _ => return None,
+        }
+    };
+
+    Some(RangeInfo::new(original_token.text_range(), nav_targets))
+}
+
+fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
+    return tokens.max_by_key(priority);
+    fn priority(n: &SyntaxToken) -> usize {
+        match n.kind() {
+            IDENT | INT_NUMBER | T![self] => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(crate) enum ReferenceResult {
+    Exact(NavigationTarget),
+    Approximate(Vec<NavigationTarget>),
+}
+
+impl ReferenceResult {
+    fn to_vec(self) -> Vec<NavigationTarget> {
+        match self {
+            ReferenceResult::Exact(target) => vec![target],
+            ReferenceResult::Approximate(vec) => vec,
+        }
+    }
+}
+
+pub(crate) fn reference_definition(
+    sema: &Semantics<RootDatabase>,
+    name_ref: &ast::NameRef,
+) -> ReferenceResult {
+    let name_kind = classify_name_ref(sema, name_ref);
+    if let Some(def) = name_kind {
+        let def = def.definition(sema.db);
+        return match def.try_to_nav(sema.db) {
+            Some(nav) => ReferenceResult::Exact(nav),
+            None => ReferenceResult::Approximate(Vec::new()),
+        };
+    }
+
+    // Fallback index based approach:
+    let navs = symbol_index::index_resolve(sema.db, name_ref)
+        .into_iter()
+        .map(|s| s.to_nav(sema.db))
+        .collect();
+    ReferenceResult::Approximate(navs)
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FileRange;
+    use syntax::{TextRange, TextSize};
+
+    use crate::mock_analysis::MockAnalysis;
+
+    fn check(ra_fixture: &str) {
+        let (mock, position) = MockAnalysis::with_files_and_position(ra_fixture);
+        let (mut expected, data) = mock.annotation();
+        let analysis = mock.analysis();
+        match data.as_str() {
+            "" => (),
+            "file" => {
+                expected.range =
+                    TextRange::up_to(TextSize::of(&*analysis.file_text(expected.file_id).unwrap()))
+            }
+            data => panic!("bad data: {}", data),
+        }
+
+        let mut navs =
+            analysis.goto_definition(position).unwrap().expect("no definition found").info;
+        if navs.len() == 0 {
+            panic!("unresolved reference")
+        }
+        assert_eq!(navs.len(), 1);
+
+        let nav = navs.pop().unwrap();
+        assert_eq!(expected, FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() });
+    }
+
+    #[test]
+    fn goto_def_for_extern_crate() {
+        check(
+            r#"
+            //- /main.rs
+            extern crate std<|>;
+            //- /std/lib.rs
+            // empty
+            //^ file
+            "#,
+        )
+    }
+
+    #[test]
+    fn goto_def_for_renamed_extern_crate() {
+        check(
+            r#"
+            //- /main.rs
+            extern crate std as abc<|>;
+            //- /std/lib.rs
+            // empty
+            //^ file
+            "#,
+        )
+    }
+
+    #[test]
+    fn goto_def_in_items() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+enum E { X(Foo<|>) }
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_at_start_of_item() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+enum E { X(<|>Foo) }
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_definition_resolves_correct_name() {
+        check(
+            r#"
+//- /lib.rs
+use a::Foo;
+mod a;
+mod b;
+enum E { X(Foo<|>) }
+
+//- /a.rs
+struct Foo;
+     //^^^
+//- /b.rs
+struct Foo;
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_module_declaration() {
+        check(
+            r#"
+//- /lib.rs
+mod <|>foo;
+
+//- /foo.rs
+// empty
+//^ file
+"#,
+        );
+
+        check(
+            r#"
+//- /lib.rs
+mod <|>foo;
+
+//- /foo/mod.rs
+// empty
+//^ file
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_macros() {
+        check(
+            r#"
+macro_rules! foo { () => { () } }
+           //^^^
+fn bar() {
+    <|>foo!();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_macros_from_other_crates() {
+        check(
+            r#"
+//- /lib.rs
+use foo::foo;
+fn bar() {
+    <|>foo!();
+}
+
+//- /foo/lib.rs
+#[macro_export]
+macro_rules! foo { () => { () } }
+           //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_macros_in_use_tree() {
+        check(
+            r#"
+//- /lib.rs
+use foo::foo<|>;
+
+//- /foo/lib.rs
+#[macro_export]
+macro_rules! foo { () => { () } }
+           //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_macro_defined_fn_with_arg() {
+        check(
+            r#"
+//- /lib.rs
+macro_rules! define_fn {
+    ($name:ident) => (fn $name() {})
+}
+
+define_fn!(foo);
+         //^^^
+
+fn bar() {
+   <|>foo();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_macro_defined_fn_no_arg() {
+        check(
+            r#"
+//- /lib.rs
+macro_rules! define_fn {
+    () => (fn foo() {})
+}
+
+  define_fn!();
+//^^^^^^^^^^^^^
+
+fn bar() {
+   <|>foo();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_definition_works_for_macro_inside_pattern() {
+        check(
+            r#"
+//- /lib.rs
+macro_rules! foo {() => {0}}
+           //^^^
+
+fn bar() {
+    match (0,1) {
+        (<|>foo!(), _) => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_definition_works_for_macro_inside_match_arm_lhs() {
+        check(
+            r#"
+//- /lib.rs
+macro_rules! foo {() => {0}}
+           //^^^
+fn bar() {
+    match 0 {
+        <|>foo!() => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_use_alias() {
+        check(
+            r#"
+//- /lib.rs
+use foo as bar<|>;
+
+//- /foo/lib.rs
+// empty
+//^ file
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_use_alias_foo_macro() {
+        check(
+            r#"
+//- /lib.rs
+use foo::foo as bar<|>;
+
+//- /foo/lib.rs
+#[macro_export]
+macro_rules! foo { () => { () } }
+           //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_methods() {
+        check(
+            r#"
+//- /lib.rs
+struct Foo;
+impl Foo {
+    fn frobnicate(&self) { }
+     //^^^^^^^^^^
+}
+
+fn bar(foo: &Foo) {
+    foo.frobnicate<|>();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_fields() {
+        check(
+            r#"
+struct Foo {
+    spam: u32,
+} //^^^^
+
+fn bar(foo: &Foo) {
+    foo.spam<|>;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_record_fields() {
+        check(
+            r#"
+//- /lib.rs
+struct Foo {
+    spam: u32,
+} //^^^^
+
+fn bar() -> Foo {
+    Foo {
+        spam<|>: 0,
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_record_pat_fields() {
+        check(
+            r#"
+//- /lib.rs
+struct Foo {
+    spam: u32,
+} //^^^^
+
+fn bar(foo: Foo) -> Foo {
+    let Foo { spam<|>: _, } = foo
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_record_fields_macros() {
+        check(
+            r"
+macro_rules! m { () => { 92 };}
+struct Foo { spam: u32 }
+           //^^^^
+
+fn bar() -> Foo {
+    Foo { spam<|>: m!() }
+}
+",
+        );
+    }
+
+    #[test]
+    fn goto_for_tuple_fields() {
+        check(
+            r#"
+struct Foo(u32);
+         //^^^
+
+fn bar() {
+    let foo = Foo(0);
+    foo.<|>0;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_ufcs_inherent_methods() {
+        check(
+            r#"
+struct Foo;
+impl Foo {
+    fn frobnicate() { }
+}    //^^^^^^^^^^
+
+fn bar(foo: &Foo) {
+    Foo::frobnicate<|>();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_ufcs_trait_methods_through_traits() {
+        check(
+            r#"
+trait Foo {
+    fn frobnicate();
+}    //^^^^^^^^^^
+
+fn bar() {
+    Foo::frobnicate<|>();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_ufcs_trait_methods_through_self() {
+        check(
+            r#"
+struct Foo;
+trait Trait {
+    fn frobnicate();
+}    //^^^^^^^^^^
+impl Trait for Foo {}
+
+fn bar() {
+    Foo::frobnicate<|>();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_definition_on_self() {
+        check(
+            r#"
+struct Foo;
+impl Foo {
+   //^^^
+    pub fn new() -> Self {
+        Self<|> {}
+    }
+}
+"#,
+        );
+        check(
+            r#"
+struct Foo;
+impl Foo {
+   //^^^
+    pub fn new() -> Self<|> {
+        Self {}
+    }
+}
+"#,
+        );
+
+        check(
+            r#"
+enum Foo { A }
+impl Foo {
+   //^^^
+    pub fn new() -> Self<|> {
+        Foo::A
+    }
+}
+"#,
+        );
+
+        check(
+            r#"
+enum Foo { A }
+impl Foo {
+   //^^^
+    pub fn thing(a: &Self<|>) {
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_definition_on_self_in_trait_impl() {
+        check(
+            r#"
+struct Foo;
+trait Make {
+    fn new() -> Self;
+}
+impl Make for Foo {
+            //^^^
+    fn new() -> Self {
+        Self<|> {}
+    }
+}
+"#,
+        );
+
+        check(
+            r#"
+struct Foo;
+trait Make {
+    fn new() -> Self;
+}
+impl Make for Foo {
+            //^^^
+    fn new() -> Self<|> {
+        Self {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_when_used_on_definition_name_itself() {
+        check(
+            r#"
+struct Foo<|> { value: u32 }
+     //^^^
+            "#,
+        );
+
+        check(
+            r#"
+struct Foo {
+    field<|>: string,
+} //^^^^^
+"#,
+        );
+
+        check(
+            r#"
+fn foo_test<|>() { }
+ //^^^^^^^^
+"#,
+        );
+
+        check(
+            r#"
+enum Foo<|> { Variant }
+   //^^^
+"#,
+        );
+
+        check(
+            r#"
+enum Foo {
+    Variant1,
+    Variant2<|>,
+  //^^^^^^^^
+    Variant3,
+}
+"#,
+        );
+
+        check(
+            r#"
+static INNER<|>: &str = "";
+     //^^^^^
+"#,
+        );
+
+        check(
+            r#"
+const INNER<|>: &str = "";
+    //^^^^^
+"#,
+        );
+
+        check(
+            r#"
+type Thing<|> = Option<()>;
+   //^^^^^
+"#,
+        );
+
+        check(
+            r#"
+trait Foo<|> { }
+    //^^^
+"#,
+        );
+
+        check(
+            r#"
+mod bar<|> { }
+  //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_from_macro() {
+        check(
+            r#"
+macro_rules! id {
+    ($($tt:tt)*) => { $($tt)* }
+}
+fn foo() {}
+ //^^^
+id! {
+    fn bar() {
+        fo<|>o();
+    }
+}
+mod confuse_index { fn foo(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_through_format() {
+        check(
+            r#"
+#[macro_export]
+macro_rules! format {
+    ($($arg:tt)*) => ($crate::fmt::format($crate::__export::format_args!($($arg)*)))
+}
+#[rustc_builtin_macro]
+#[macro_export]
+macro_rules! format_args {
+    ($fmt:expr) => ({ /* compiler built-in */ });
+    ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
+}
+pub mod __export {
+    pub use crate::format_args;
+    fn foo() {} // for index confusion
+}
+fn foo() -> i8 {}
+ //^^^
+fn test() {
+    format!("{}", fo<|>o())
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_for_type_param() {
+        check(
+            r#"
+struct Foo<T: Clone> { t: <|>T }
+         //^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_within_macro() {
+        check(
+            r#"
+macro_rules! id {
+    ($($tt:tt)*) => ($($tt)*)
+}
+
+fn foo() {
+    let x = 1;
+      //^
+    id!({
+        let y = <|>x;
+        let z = y;
+    });
+}
+"#,
+        );
+
+        check(
+            r#"
+macro_rules! id {
+    ($($tt:tt)*) => ($($tt)*)
+}
+
+fn foo() {
+    let x = 1;
+    id!({
+        let y = x;
+          //^
+        let z = <|>y;
+    });
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_in_local_fn() {
+        check(
+            r#"
+fn main() {
+    fn foo() {
+        let x = 92;
+          //^
+        <|>x;
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_in_local_macro() {
+        check(
+            r#"
+fn bar() {
+    macro_rules! foo { () => { () } }
+               //^^^
+    <|>foo!();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_field_init_shorthand() {
+        check(
+            r#"
+struct Foo { x: i32 }
+fn main() {
+    let x = 92;
+      //^
+    Foo { x<|> };
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn goto_def_for_enum_variant_field() {
+        check(
+            r#"
+enum Foo {
+    Bar { x: i32 }
+}       //^
+fn baz(foo: Foo) {
+    match foo {
+        Foo::Bar { x<|> } => x
+    };
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_enum_variant_self_pattern_const() {
+        check(
+            r#"
+enum Foo { Bar }
+         //^^^
+impl Foo {
+    fn baz(self) {
+        match self { Self::Bar<|> => {} }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_enum_variant_self_pattern_record() {
+        check(
+            r#"
+enum Foo { Bar { val: i32 } }
+         //^^^
+impl Foo {
+    fn baz(self) -> i32 {
+        match self { Self::Bar<|> { val } => {} }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_enum_variant_self_expr_const() {
+        check(
+            r#"
+enum Foo { Bar }
+         //^^^
+impl Foo {
+    fn baz(self) { Self::Bar<|>; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_enum_variant_self_expr_record() {
+        check(
+            r#"
+enum Foo { Bar { val: i32 } }
+         //^^^
+impl Foo {
+    fn baz(self) { Self::Bar<|> {val: 4}; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_type_alias_generic_parameter() {
+        check(
+            r#"
+type Alias<T> = T<|>;
+         //^
+"#,
+        )
+    }
+
+    #[test]
+    fn goto_def_for_macro_container() {
+        check(
+            r#"
+//- /lib.rs
+foo::module<|>::mac!();
+
+//- /foo/lib.rs
+pub mod module {
+      //^^^^^^
+    #[macro_export]
+    macro_rules! _mac { () => { () } }
+    pub use crate::_mac as mac;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_assoc_ty_in_path() {
+        check(
+            r#"
+trait Iterator {
+    type Item;
+       //^^^^
+}
+
+fn f() -> impl Iterator<Item<|> = u8> {}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_assoc_ty_in_path_multiple() {
+        check(
+            r#"
+trait Iterator {
+    type A;
+       //^
+    type B;
+}
+
+fn f() -> impl Iterator<A<|> = u8, B = ()> {}
+"#,
+        );
+        check(
+            r#"
+trait Iterator {
+    type A;
+    type B;
+       //^
+}
+
+fn f() -> impl Iterator<A = u8, B<|> = ()> {}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_assoc_ty_ufcs() {
+        check(
+            r#"
+trait Iterator {
+    type Item;
+       //^^^^
+}
+
+fn g() -> <() as Iterator<Item<|> = ()>>::Item {}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_assoc_ty_ufcs_multiple() {
+        check(
+            r#"
+trait Iterator {
+    type A;
+       //^
+    type B;
+}
+
+fn g() -> <() as Iterator<A<|> = (), B = u8>>::B {}
+"#,
+        );
+        check(
+            r#"
+trait Iterator {
+    type A;
+    type B;
+       //^
+}
+
+fn g() -> <() as Iterator<A = (), B<|> = u8>>::A {}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/goto_implementation.rs b/crates/ide/src/goto_implementation.rs
new file mode 100644
index 000000000..f503f4ec5
--- /dev/null
+++ b/crates/ide/src/goto_implementation.rs
@@ -0,0 +1,229 @@
+use hir::{Crate, ImplDef, Semantics};
+use ide_db::RootDatabase;
+use syntax::{algo::find_node_at_offset, ast, AstNode};
+
+use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
+
+// Feature: Go to Implementation
+//
+// Navigates to the impl block of structs, enums or traits. Also implemented as a code lens.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+F12]
+// |===
+pub(crate) fn goto_implementation(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(position.file_id);
+    let syntax = source_file.syntax().clone();
+
+    let krate = sema.to_module_def(position.file_id)?.krate();
+
+    if let Some(nominal_def) = find_node_at_offset::<ast::AdtDef>(&syntax, position.offset) {
+        return Some(RangeInfo::new(
+            nominal_def.syntax().text_range(),
+            impls_for_def(&sema, &nominal_def, krate)?,
+        ));
+    } else if let Some(trait_def) = find_node_at_offset::<ast::Trait>(&syntax, position.offset) {
+        return Some(RangeInfo::new(
+            trait_def.syntax().text_range(),
+            impls_for_trait(&sema, &trait_def, krate)?,
+        ));
+    }
+
+    None
+}
+
+fn impls_for_def(
+    sema: &Semantics<RootDatabase>,
+    node: &ast::AdtDef,
+    krate: Crate,
+) -> Option<Vec<NavigationTarget>> {
+    let ty = match node {
+        ast::AdtDef::Struct(def) => sema.to_def(def)?.ty(sema.db),
+        ast::AdtDef::Enum(def) => sema.to_def(def)?.ty(sema.db),
+        ast::AdtDef::Union(def) => sema.to_def(def)?.ty(sema.db),
+    };
+
+    let impls = ImplDef::all_in_crate(sema.db, krate);
+
+    Some(
+        impls
+            .into_iter()
+            .filter(|impl_def| ty.is_equal_for_find_impls(&impl_def.target_ty(sema.db)))
+            .map(|imp| imp.to_nav(sema.db))
+            .collect(),
+    )
+}
+
+fn impls_for_trait(
+    sema: &Semantics<RootDatabase>,
+    node: &ast::Trait,
+    krate: Crate,
+) -> Option<Vec<NavigationTarget>> {
+    let tr = sema.to_def(node)?;
+
+    let impls = ImplDef::for_trait(sema.db, krate, tr);
+
+    Some(impls.into_iter().map(|imp| imp.to_nav(sema.db)).collect())
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FileRange;
+
+    use crate::mock_analysis::MockAnalysis;
+
+    fn check(ra_fixture: &str) {
+        let (mock, position) = MockAnalysis::with_files_and_position(ra_fixture);
+        let annotations = mock.annotations();
+        let analysis = mock.analysis();
+
+        let navs = analysis.goto_implementation(position).unwrap().unwrap().info;
+
+        let key = |frange: &FileRange| (frange.file_id, frange.range.start());
+
+        let mut expected = annotations
+            .into_iter()
+            .map(|(range, data)| {
+                assert!(data.is_empty());
+                range
+            })
+            .collect::<Vec<_>>();
+        expected.sort_by_key(key);
+
+        let mut actual = navs
+            .into_iter()
+            .map(|nav| FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() })
+            .collect::<Vec<_>>();
+        actual.sort_by_key(key);
+
+        assert_eq!(expected, actual);
+    }
+
+    #[test]
+    fn goto_implementation_works() {
+        check(
+            r#"
+struct Foo<|>;
+impl Foo {}
+   //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_blocks() {
+        check(
+            r#"
+struct Foo<|>;
+impl Foo {}
+   //^^^
+impl Foo {}
+   //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_mods() {
+        check(
+            r#"
+struct Foo<|>;
+mod a {
+    impl super::Foo {}
+       //^^^^^^^^^^
+}
+mod b {
+    impl super::Foo {}
+       //^^^^^^^^^^
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_works_multiple_files() {
+        check(
+            r#"
+//- /lib.rs
+struct Foo<|>;
+mod a;
+mod b;
+//- /a.rs
+impl crate::Foo {}
+   //^^^^^^^^^^
+//- /b.rs
+impl crate::Foo {}
+   //^^^^^^^^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_for_trait() {
+        check(
+            r#"
+trait T<|> {}
+struct Foo;
+impl T for Foo {}
+         //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_for_trait_multiple_files() {
+        check(
+            r#"
+//- /lib.rs
+trait T<|> {};
+struct Foo;
+mod a;
+mod b;
+//- /a.rs
+impl crate::T for crate::Foo {}
+                //^^^^^^^^^^
+//- /b.rs
+impl crate::T for crate::Foo {}
+                //^^^^^^^^^^
+            "#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_all_impls() {
+        check(
+            r#"
+//- /lib.rs
+trait T {}
+struct Foo<|>;
+impl Foo {}
+   //^^^
+impl T for Foo {}
+         //^^^
+impl T for &Foo {}
+         //^^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_to_builtin_derive() {
+        check(
+            r#"
+  #[derive(Copy)]
+//^^^^^^^^^^^^^^^
+struct Foo<|>;
+
+mod marker {
+    trait Copy {}
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/goto_type_definition.rs b/crates/ide/src/goto_type_definition.rs
new file mode 100644
index 000000000..4a151b150
--- /dev/null
+++ b/crates/ide/src/goto_type_definition.rs
@@ -0,0 +1,151 @@
+use ide_db::RootDatabase;
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
+
+use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
+
+// Feature: Go to Type Definition
+//
+// Navigates to the type of an identifier.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Go to Type Definition*
+// |===
+pub(crate) fn goto_type_definition(
+    db: &RootDatabase,
+    position: FilePosition,
+) -> Option<RangeInfo<Vec<NavigationTarget>>> {
+    let sema = hir::Semantics::new(db);
+
+    let file: ast::SourceFile = sema.parse(position.file_id);
+    let token: SyntaxToken = pick_best(file.syntax().token_at_offset(position.offset))?;
+    let token: SyntaxToken = sema.descend_into_macros(token);
+
+    let (ty, node) = sema.ancestors_with_macros(token.parent()).find_map(|node| {
+        let ty = match_ast! {
+            match node {
+                ast::Expr(it) => sema.type_of_expr(&it)?,
+                ast::Pat(it) => sema.type_of_pat(&it)?,
+                ast::SelfParam(it) => sema.type_of_self(&it)?,
+                _ => return None,
+            }
+        };
+
+        Some((ty, node))
+    })?;
+
+    let adt_def = ty.autoderef(db).filter_map(|ty| ty.as_adt()).last()?;
+
+    let nav = adt_def.to_nav(db);
+    Some(RangeInfo::new(node.text_range(), vec![nav]))
+}
+
+fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
+    return tokens.max_by_key(priority);
+    fn priority(n: &SyntaxToken) -> usize {
+        match n.kind() {
+            IDENT | INT_NUMBER | T![self] => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FileRange;
+
+    use crate::mock_analysis::MockAnalysis;
+
+    fn check(ra_fixture: &str) {
+        let (mock, position) = MockAnalysis::with_files_and_position(ra_fixture);
+        let (expected, data) = mock.annotation();
+        assert!(data.is_empty());
+        let analysis = mock.analysis();
+
+        let mut navs = analysis.goto_type_definition(position).unwrap().unwrap().info;
+        assert_eq!(navs.len(), 1);
+        let nav = navs.pop().unwrap();
+        assert_eq!(expected, FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() });
+    }
+
+    #[test]
+    fn goto_type_definition_works_simple() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo() {
+    let f: Foo; f<|>
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_works_simple_ref() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo() {
+    let f: &Foo; f<|>
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_works_through_macro() {
+        check(
+            r#"
+macro_rules! id { ($($tt:tt)*) => { $($tt)* } }
+struct Foo {}
+     //^^^
+id! {
+    fn bar() { let f<|> = Foo {}; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_for_param() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+fn foo(<|>f: Foo) {}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_type_definition_for_tuple_field() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+struct Bar(Foo);
+fn foo() {
+    let bar = Bar(Foo);
+    bar.<|>0;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_def_for_self_param() {
+        check(
+            r#"
+struct Foo;
+     //^^^
+impl Foo {
+    fn f(&self<|>) {}
+}
+"#,
+        )
+    }
+}
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
new file mode 100644
index 000000000..b012e4900
--- /dev/null
+++ b/crates/ide/src/hover.rs
@@ -0,0 +1,2967 @@
+use base_db::SourceDatabase;
+use hir::{
+    Adt, AsAssocItem, AssocItemContainer, Documentation, FieldSource, HasSource, HirDisplay,
+    Module, ModuleDef, ModuleSource, Semantics,
+};
+use ide_db::{
+    defs::{classify_name, classify_name_ref, Definition},
+    RootDatabase,
+};
+use itertools::Itertools;
+use stdx::format_to;
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
+use test_utils::mark;
+
+use crate::{
+    display::{macro_label, ShortLabel, ToNav, TryToNav},
+    link_rewrite::rewrite_links,
+    markup::Markup,
+    runnables::runnable,
+    FileId, FilePosition, NavigationTarget, RangeInfo, Runnable,
+};
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HoverConfig {
+    pub implementations: bool,
+    pub run: bool,
+    pub debug: bool,
+    pub goto_type_def: bool,
+}
+
+impl Default for HoverConfig {
+    fn default() -> Self {
+        Self { implementations: true, run: true, debug: true, goto_type_def: true }
+    }
+}
+
+impl HoverConfig {
+    pub const NO_ACTIONS: Self =
+        Self { implementations: false, run: false, debug: false, goto_type_def: false };
+
+    pub fn any(&self) -> bool {
+        self.implementations || self.runnable() || self.goto_type_def
+    }
+
+    pub fn none(&self) -> bool {
+        !self.any()
+    }
+
+    pub fn runnable(&self) -> bool {
+        self.run || self.debug
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum HoverAction {
+    Runnable(Runnable),
+    Implementaion(FilePosition),
+    GoToType(Vec<HoverGotoTypeData>),
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct HoverGotoTypeData {
+    pub mod_path: String,
+    pub nav: NavigationTarget,
+}
+
+/// Contains the results when hovering over an item
+#[derive(Debug, Default)]
+pub struct HoverResult {
+    pub markup: Markup,
+    pub actions: Vec<HoverAction>,
+}
+
+// Feature: Hover
+//
+// Shows additional information, like type of an expression or documentation for definition when "focusing" code.
+// Focusing is usually hovering with a mouse, but can also be triggered with a shortcut.
+pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<HoverResult>> {
+    let sema = Semantics::new(db);
+    let file = sema.parse(position.file_id).syntax().clone();
+    let token = pick_best(file.token_at_offset(position.offset))?;
+    let token = sema.descend_into_macros(token);
+
+    let mut res = HoverResult::default();
+
+    let node = token.parent();
+    let definition = match_ast! {
+        match node {
+            ast::NameRef(name_ref) => classify_name_ref(&sema, &name_ref).map(|d| d.definition(sema.db)),
+            ast::Name(name) => classify_name(&sema, &name).map(|d| d.definition(sema.db)),
+            _ => None,
+        }
+    };
+    if let Some(definition) = definition {
+        if let Some(markup) = hover_for_definition(db, definition) {
+            let markup = rewrite_links(db, &markup.as_str(), &definition);
+            res.markup = Markup::from(markup);
+            if let Some(action) = show_implementations_action(db, definition) {
+                res.actions.push(action);
+            }
+
+            if let Some(action) = runnable_action(&sema, definition, position.file_id) {
+                res.actions.push(action);
+            }
+
+            if let Some(action) = goto_type_action(db, definition) {
+                res.actions.push(action);
+            }
+
+            let range = sema.original_range(&node).range;
+            return Some(RangeInfo::new(range, res));
+        }
+    }
+
+    let node = token
+        .ancestors()
+        .find(|n| ast::Expr::cast(n.clone()).is_some() || ast::Pat::cast(n.clone()).is_some())?;
+
+    let ty = match_ast! {
+        match node {
+            ast::Expr(it) => sema.type_of_expr(&it)?,
+            ast::Pat(it) => sema.type_of_pat(&it)?,
+            // If this node is a MACRO_CALL, it means that `descend_into_macros` failed to resolve.
+            // (e.g expanding a builtin macro). So we give up here.
+            ast::MacroCall(_it) => return None,
+            _ => return None,
+        }
+    };
+
+    res.markup = Markup::fenced_block(&ty.display(db));
+    let range = sema.original_range(&node).range;
+    Some(RangeInfo::new(range, res))
+}
+
+fn show_implementations_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
+    fn to_action(nav_target: NavigationTarget) -> HoverAction {
+        HoverAction::Implementaion(FilePosition {
+            file_id: nav_target.file_id,
+            offset: nav_target.focus_or_full_range().start(),
+        })
+    }
+
+    match def {
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Trait(it) => Some(to_action(it.to_nav(db))),
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+fn runnable_action(
+    sema: &Semantics<RootDatabase>,
+    def: Definition,
+    file_id: FileId,
+) -> Option<HoverAction> {
+    match def {
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Module(it) => match it.definition_source(sema.db).value {
+                ModuleSource::Module(it) => runnable(&sema, it.syntax().clone(), file_id)
+                    .map(|it| HoverAction::Runnable(it)),
+                _ => None,
+            },
+            ModuleDef::Function(it) => {
+                let src = it.source(sema.db);
+                if src.file_id != file_id.into() {
+                    mark::hit!(hover_macro_generated_struct_fn_doc_comment);
+                    mark::hit!(hover_macro_generated_struct_fn_doc_attr);
+
+                    return None;
+                }
+
+                runnable(&sema, src.value.syntax().clone(), file_id)
+                    .map(|it| HoverAction::Runnable(it))
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+fn goto_type_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
+    match def {
+        Definition::Local(it) => {
+            let mut targets: Vec<ModuleDef> = Vec::new();
+            let mut push_new_def = |item: ModuleDef| {
+                if !targets.contains(&item) {
+                    targets.push(item);
+                }
+            };
+
+            it.ty(db).walk(db, |t| {
+                if let Some(adt) = t.as_adt() {
+                    push_new_def(adt.into());
+                } else if let Some(trait_) = t.as_dyn_trait() {
+                    push_new_def(trait_.into());
+                } else if let Some(traits) = t.as_impl_traits(db) {
+                    traits.into_iter().for_each(|it| push_new_def(it.into()));
+                } else if let Some(trait_) = t.as_associated_type_parent_trait(db) {
+                    push_new_def(trait_.into());
+                }
+            });
+
+            let targets = targets
+                .into_iter()
+                .filter_map(|it| {
+                    Some(HoverGotoTypeData {
+                        mod_path: render_path(
+                            db,
+                            it.module(db)?,
+                            it.name(db).map(|name| name.to_string()),
+                        ),
+                        nav: it.try_to_nav(db)?,
+                    })
+                })
+                .collect();
+
+            Some(HoverAction::GoToType(targets))
+        }
+        _ => None,
+    }
+}
+
+fn hover_markup(
+    docs: Option<String>,
+    desc: Option<String>,
+    mod_path: Option<String>,
+) -> Option<Markup> {
+    match desc {
+        Some(desc) => {
+            let mut buf = String::new();
+
+            if let Some(mod_path) = mod_path {
+                if !mod_path.is_empty() {
+                    format_to!(buf, "```rust\n{}\n```\n\n", mod_path);
+                }
+            }
+            format_to!(buf, "```rust\n{}\n```", desc);
+
+            if let Some(doc) = docs {
+                format_to!(buf, "\n___\n\n{}", doc);
+            }
+            Some(buf.into())
+        }
+        None => docs.map(Markup::from),
+    }
+}
+
+fn definition_owner_name(db: &RootDatabase, def: &Definition) -> Option<String> {
+    match def {
+        Definition::Field(f) => Some(f.parent_def(db).name(db)),
+        Definition::Local(l) => l.parent(db).name(db),
+        Definition::ModuleDef(md) => match md {
+            ModuleDef::Function(f) => match f.as_assoc_item(db)?.container(db) {
+                AssocItemContainer::Trait(t) => Some(t.name(db)),
+                AssocItemContainer::ImplDef(i) => i.target_ty(db).as_adt().map(|adt| adt.name(db)),
+            },
+            ModuleDef::EnumVariant(e) => Some(e.parent_enum(db).name(db)),
+            _ => None,
+        },
+        Definition::SelfType(i) => i.target_ty(db).as_adt().map(|adt| adt.name(db)),
+        _ => None,
+    }
+    .map(|name| name.to_string())
+}
+
+fn render_path(db: &RootDatabase, module: Module, item_name: Option<String>) -> String {
+    let crate_name =
+        db.crate_graph()[module.krate().into()].display_name.as_ref().map(ToString::to_string);
+    let module_path = module
+        .path_to_root(db)
+        .into_iter()
+        .rev()
+        .flat_map(|it| it.name(db).map(|name| name.to_string()));
+    crate_name.into_iter().chain(module_path).chain(item_name).join("::")
+}
+
+fn definition_mod_path(db: &RootDatabase, def: &Definition) -> Option<String> {
+    def.module(db).map(|module| render_path(db, module, definition_owner_name(db, def)))
+}
+
+fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
+    let mod_path = definition_mod_path(db, &def);
+    return match def {
+        Definition::Macro(it) => {
+            let src = it.source(db);
+            let docs = Documentation::from_ast(&src.value).map(Into::into);
+            hover_markup(docs, Some(macro_label(&src.value)), mod_path)
+        }
+        Definition::Field(it) => {
+            let src = it.source(db);
+            match src.value {
+                FieldSource::Named(it) => {
+                    let docs = Documentation::from_ast(&it).map(Into::into);
+                    hover_markup(docs, it.short_label(), mod_path)
+                }
+                _ => None,
+            }
+        }
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Module(it) => match it.definition_source(db).value {
+                ModuleSource::Module(it) => {
+                    let docs = Documentation::from_ast(&it).map(Into::into);
+                    hover_markup(docs, it.short_label(), mod_path)
+                }
+                ModuleSource::SourceFile(it) => {
+                    let docs = Documentation::from_ast(&it).map(Into::into);
+                    hover_markup(docs, it.short_label(), mod_path)
+                }
+            },
+            ModuleDef::Function(it) => from_def_source(db, it, mod_path),
+            ModuleDef::Adt(Adt::Struct(it)) => from_def_source(db, it, mod_path),
+            ModuleDef::Adt(Adt::Union(it)) => from_def_source(db, it, mod_path),
+            ModuleDef::Adt(Adt::Enum(it)) => from_def_source(db, it, mod_path),
+            ModuleDef::EnumVariant(it) => from_def_source(db, it, mod_path),
+            ModuleDef::Const(it) => from_def_source(db, it, mod_path),
+            ModuleDef::Static(it) => from_def_source(db, it, mod_path),
+            ModuleDef::Trait(it) => from_def_source(db, it, mod_path),
+            ModuleDef::TypeAlias(it) => from_def_source(db, it, mod_path),
+            ModuleDef::BuiltinType(it) => return Some(it.to_string().into()),
+        },
+        Definition::Local(it) => return Some(Markup::fenced_block(&it.ty(db).display(db))),
+        Definition::TypeParam(_) | Definition::SelfType(_) => {
+            // FIXME: Hover for generic param
+            None
+        }
+    };
+
+    fn from_def_source<A, D>(db: &RootDatabase, def: D, mod_path: Option<String>) -> Option<Markup>
+    where
+        D: HasSource<Ast = A>,
+        A: ast::DocCommentsOwner + ast::NameOwner + ShortLabel + ast::AttrsOwner,
+    {
+        let src = def.source(db);
+        let docs = Documentation::from_ast(&src.value).map(Into::into);
+        hover_markup(docs, src.value.short_label(), mod_path)
+    }
+}
+
+fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
+    return tokens.max_by_key(priority);
+    fn priority(n: &SyntaxToken) -> usize {
+        match n.kind() {
+            IDENT | INT_NUMBER => 3,
+            T!['('] | T![')'] => 2,
+            kind if kind.is_trivia() => 0,
+            _ => 1,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::FileLoader;
+    use expect_test::{expect, Expect};
+
+    use crate::mock_analysis::analysis_and_position;
+
+    use super::*;
+
+    fn check_hover_no_result(ra_fixture: &str) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        assert!(analysis.hover(position).unwrap().is_none());
+    }
+
+    fn check(ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let hover = analysis.hover(position).unwrap().unwrap();
+
+        let content = analysis.db.file_text(position.file_id);
+        let hovered_element = &content[hover.range];
+
+        let actual = format!("*{}*\n{}\n", hovered_element, hover.info.markup);
+        expect.assert_eq(&actual)
+    }
+
+    fn check_actions(ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let hover = analysis.hover(position).unwrap().unwrap();
+        expect.assert_debug_eq(&hover.info.actions)
+    }
+
+    #[test]
+    fn hover_shows_type_of_an_expression() {
+        check(
+            r#"
+pub fn foo() -> u32 { 1 }
+
+fn main() {
+    let foo_test = foo()<|>;
+}
+"#,
+            expect![[r#"
+                *foo()*
+                ```rust
+                u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_long_type_of_an_expression() {
+        check(
+            r#"
+struct Scan<A, B, C> { a: A, b: B, c: C }
+struct Iter<I> { inner: I }
+enum Option<T> { Some(T), None }
+
+struct OtherStruct<T> { i: T }
+
+fn scan<A, B, C>(a: A, b: B, c: C) -> Iter<Scan<OtherStruct<A>, B, C>> {
+    Iter { inner: Scan { a, b, c } }
+}
+
+fn main() {
+    let num: i32 = 55;
+    let closure = |memo: &mut u32, value: &u32, _another: &mut u32| -> Option<u32> {
+        Option::Some(*memo + value)
+    };
+    let number = 5u32;
+    let mut iter<|> = scan(OtherStruct { i: num }, closure, number);
+}
+"#,
+            expect![[r#"
+                *iter*
+
+                ```rust
+                Iter<Scan<OtherStruct<OtherStruct<i32>>, |&mut u32, &u32, &mut u32| -> Option<u32>, u32>>
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_signature() {
+        // Single file with result
+        check(
+            r#"
+pub fn foo() -> u32 { 1 }
+
+fn main() { let foo_test = fo<|>o(); }
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub fn foo() -> u32
+                ```
+            "#]],
+        );
+
+        // Multiple candidates but results are ambiguous.
+        check(
+            r#"
+//- /a.rs
+pub fn foo() -> u32 { 1 }
+
+//- /b.rs
+pub fn foo() -> &str { "" }
+
+//- /c.rs
+pub fn foo(a: u32, b: u32) {}
+
+//- /main.rs
+mod a;
+mod b;
+mod c;
+
+fn main() { let foo_test = fo<|>o(); }
+        "#,
+            expect![[r#"
+                *foo*
+                ```rust
+                {unknown}
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_signature_with_type_params() {
+        check(
+            r#"
+pub fn foo<'a, T: AsRef<str>>(b: &'a T) -> &'a str { }
+
+fn main() { let foo_test = fo<|>o(); }
+        "#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub fn foo<'a, T: AsRef<str>>(b: &'a T) -> &'a str
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_signature_on_fn_name() {
+        check(
+            r#"
+pub fn foo<|>(a: u32, b: u32) -> u32 {}
+
+fn main() { }
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub fn foo(a: u32, b: u32) -> u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_doc() {
+        check(
+            r#"
+/// # Example
+/// ```
+/// # use std::path::Path;
+/// #
+/// foo(Path::new("hello, world!"))
+/// ```
+pub fn foo<|>(_: &Path) {}
+
+fn main() { }
+"#,
+            expect![[r##"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub fn foo(_: &Path)
+                ```
+
+                ---
+
+                # Example
+
+                ```
+                # use std::path::Path;
+                #
+                foo(Path::new("hello, world!"))
+                ```
+            "##]],
+        );
+    }
+
+    #[test]
+    fn hover_shows_struct_field_info() {
+        // Hovering over the field when instantiating
+        check(
+            r#"
+struct Foo { field_a: u32 }
+
+fn main() {
+    let foo = Foo { field_a<|>: 0, };
+}
+"#,
+            expect![[r#"
+                *field_a*
+
+                ```rust
+                test::Foo
+                ```
+
+                ```rust
+                field_a: u32
+                ```
+            "#]],
+        );
+
+        // Hovering over the field in the definition
+        check(
+            r#"
+struct Foo { field_a<|>: u32 }
+
+fn main() {
+    let foo = Foo { field_a: 0 };
+}
+"#,
+            expect![[r#"
+                *field_a*
+
+                ```rust
+                test::Foo
+                ```
+
+                ```rust
+                field_a: u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_const_static() {
+        check(
+            r#"const foo<|>: u32 = 123;"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                const foo: u32 = 123
+                ```
+            "#]],
+        );
+        check(
+            r#"static foo<|>: u32 = 456;"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                static foo: u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_default_generic_types() {
+        check(
+            r#"
+struct Test<K, T = u8> { k: K, t: T }
+
+fn main() {
+    let zz<|> = Test { t: 23u8, k: 33 };
+}"#,
+            expect![[r#"
+                *zz*
+
+                ```rust
+                Test<i32, u8>
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_some() {
+        check(
+            r#"
+enum Option<T> { Some(T) }
+use Option::Some;
+
+fn main() { So<|>me(12); }
+"#,
+            expect![[r#"
+                *Some*
+
+                ```rust
+                test::Option
+                ```
+
+                ```rust
+                Some
+                ```
+            "#]],
+        );
+
+        check(
+            r#"
+enum Option<T> { Some(T) }
+use Option::Some;
+
+fn main() { let b<|>ar = Some(12); }
+"#,
+            expect![[r#"
+                *bar*
+
+                ```rust
+                Option<i32>
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_enum_variant() {
+        check(
+            r#"
+enum Option<T> {
+    /// The None variant
+    Non<|>e
+}
+"#,
+            expect![[r#"
+                *None*
+
+                ```rust
+                test::Option
+                ```
+
+                ```rust
+                None
+                ```
+
+                ---
+
+                The None variant
+            "#]],
+        );
+
+        check(
+            r#"
+enum Option<T> {
+    /// The Some variant
+    Some(T)
+}
+fn main() {
+    let s = Option::Som<|>e(12);
+}
+"#,
+            expect![[r#"
+                *Some*
+
+                ```rust
+                test::Option
+                ```
+
+                ```rust
+                Some
+                ```
+
+                ---
+
+                The Some variant
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_for_local_variable() {
+        check(
+            r#"fn func(foo: i32) { fo<|>o; }"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                i32
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn hover_for_local_variable_pat() {
+        check(
+            r#"fn func(fo<|>o: i32) {}"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                i32
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn hover_local_var_edge() {
+        check(
+            r#"fn func(foo: i32) { if true { <|>foo; }; }"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                i32
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn hover_for_param_edge() {
+        check(
+            r#"fn func(<|>foo: i32) {}"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                i32
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn hover_for_param_with_multiple_traits() {
+        check(
+            r#"trait Deref {
+                type Target: ?Sized;
+            }
+            trait DerefMut {
+                type Target: ?Sized;
+            }
+            fn f(_x<|>: impl Deref<Target=u8> + DerefMut<Target=u8>) {}"#,
+            expect![[r#"
+                *_x*
+
+                ```rust
+                impl Deref<Target = u8> + DerefMut<Target = u8>
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_infer_associated_method_result() {
+        check(
+            r#"
+struct Thing { x: u32 }
+
+impl Thing {
+    fn new() -> Thing { Thing { x: 0 } }
+}
+
+fn main() { let foo_<|>test = Thing::new(); }
+            "#,
+            expect![[r#"
+                *foo_test*
+
+                ```rust
+                Thing
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_infer_associated_method_exact() {
+        check(
+            r#"
+mod wrapper {
+    struct Thing { x: u32 }
+
+    impl Thing {
+        fn new() -> Thing { Thing { x: 0 } }
+    }
+}
+
+fn main() { let foo_test = wrapper::Thing::new<|>(); }
+"#,
+            expect![[r#"
+                *new*
+
+                ```rust
+                test::wrapper::Thing
+                ```
+
+                ```rust
+                fn new() -> Thing
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_infer_associated_const_in_pattern() {
+        check(
+            r#"
+struct X;
+impl X {
+    const C: u32 = 1;
+}
+
+fn main() {
+    match 1 {
+        X::C<|> => {},
+        2 => {},
+        _ => {}
+    };
+}
+"#,
+            expect![[r#"
+                *C*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                const C: u32 = 1
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_self() {
+        check(
+            r#"
+struct Thing { x: u32 }
+impl Thing {
+    fn new() -> Self { Self<|> { x: 0 } }
+}
+"#,
+            expect![[r#"
+                *Self { x: 0 }*
+                ```rust
+                Thing
+                ```
+            "#]],
+        )
+    } /* FIXME: revive these tests
+              let (analysis, position) = analysis_and_position(
+                  "
+                  struct Thing { x: u32 }
+                  impl Thing {
+                      fn new() -> Self<|> {
+                          Self { x: 0 }
+                      }
+                  }
+                  ",
+              );
+
+              let hover = analysis.hover(position).unwrap().unwrap();
+              assert_eq!(trim_markup(&hover.info.markup.as_str()), ("Thing"));
+
+              let (analysis, position) = analysis_and_position(
+                  "
+                  enum Thing { A }
+                  impl Thing {
+                      pub fn new() -> Self<|> {
+                          Thing::A
+                      }
+                  }
+                  ",
+              );
+              let hover = analysis.hover(position).unwrap().unwrap();
+              assert_eq!(trim_markup(&hover.info.markup.as_str()), ("enum Thing"));
+
+              let (analysis, position) = analysis_and_position(
+                  "
+                  enum Thing { A }
+                  impl Thing {
+                      pub fn thing(a: Self<|>) {
+                      }
+                  }
+                  ",
+              );
+              let hover = analysis.hover(position).unwrap().unwrap();
+              assert_eq!(trim_markup(&hover.info.markup.as_str()), ("enum Thing"));
+      */
+
+    #[test]
+    fn test_hover_shadowing_pat() {
+        check(
+            r#"
+fn x() {}
+
+fn y() {
+    let x = 0i32;
+    x<|>;
+}
+"#,
+            expect![[r#"
+                *x*
+
+                ```rust
+                i32
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_macro_invocation() {
+        check(
+            r#"
+macro_rules! foo { () => {} }
+
+fn f() { fo<|>o!(); }
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                macro_rules! foo
+                ```
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_tuple_field() {
+        check(
+            r#"struct TS(String, i32<|>);"#,
+            expect![[r#"
+                *i32*
+                i32
+            "#]],
+        )
+    }
+
+    #[test]
+    fn test_hover_through_macro() {
+        check(
+            r#"
+macro_rules! id { ($($tt:tt)*) => { $($tt)* } }
+fn foo() {}
+id! {
+    fn bar() { fo<|>o(); }
+}
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                fn foo()
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_expr_in_macro() {
+        check(
+            r#"
+macro_rules! id { ($($tt:tt)*) => { $($tt)* } }
+fn foo(bar:u32) { let a = id!(ba<|>r); }
+"#,
+            expect![[r#"
+                *bar*
+
+                ```rust
+                u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_expr_in_macro_recursive() {
+        check(
+            r#"
+macro_rules! id_deep { ($($tt:tt)*) => { $($tt)* } }
+macro_rules! id { ($($tt:tt)*) => { id_deep!($($tt)*) } }
+fn foo(bar:u32) { let a = id!(ba<|>r); }
+"#,
+            expect![[r#"
+                *bar*
+
+                ```rust
+                u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_func_in_macro_recursive() {
+        check(
+            r#"
+macro_rules! id_deep { ($($tt:tt)*) => { $($tt)* } }
+macro_rules! id { ($($tt:tt)*) => { id_deep!($($tt)*) } }
+fn bar() -> u32 { 0 }
+fn foo() { let a = id!([0u32, bar(<|>)] ); }
+"#,
+            expect![[r#"
+                *bar()*
+                ```rust
+                u32
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_literal_string_in_macro() {
+        check(
+            r#"
+macro_rules! arr { ($($tt:tt)*) => { [$($tt)*)] } }
+fn foo() {
+    let mastered_for_itunes = "";
+    let _ = arr!("Tr<|>acks", &mastered_for_itunes);
+}
+"#,
+            expect![[r#"
+                *"Tracks"*
+                ```rust
+                &str
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_assert_macro() {
+        check(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! assert {}
+
+fn bar() -> bool { true }
+fn foo() {
+    assert!(ba<|>r());
+}
+"#,
+            expect![[r#"
+                *bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                fn bar() -> bool
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_through_literal_string_in_builtin_macro() {
+        check_hover_no_result(
+            r#"
+            #[rustc_builtin_macro]
+            macro_rules! format {}
+
+            fn foo() {
+                format!("hel<|>lo {}", 0);
+            }
+            "#,
+        );
+    }
+
+    #[test]
+    fn test_hover_non_ascii_space_doc() {
+        check(
+            "
+///　<- `\u{3000}` here
+fn foo() { }
+
+fn bar() { fo<|>o(); }
+",
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                fn foo()
+                ```
+
+                ---
+
+                \<- `　` here
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_function_show_qualifiers() {
+        check(
+            r#"async fn foo<|>() {}"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                async fn foo()
+                ```
+            "#]],
+        );
+        check(
+            r#"pub const unsafe fn foo<|>() {}"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub const unsafe fn foo()
+                ```
+            "#]],
+        );
+        check(
+            r#"pub(crate) async unsafe extern "C" fn foo<|>() {}"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub(crate) async unsafe extern "C" fn foo()
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_trait_show_qualifiers() {
+        check_actions(
+            r"unsafe trait foo<|>() {}",
+            expect![[r#"
+                [
+                    Implementaion(
+                        FilePosition {
+                            file_id: FileId(
+                                1,
+                            ),
+                            offset: 13,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_extern_crate() {
+        check(
+            r#"
+//- /main.rs
+extern crate st<|>d;
+//- /std/lib.rs
+//! Standard library for this test
+//!
+//! Printed?
+//! abc123
+            "#,
+            expect![[r#"
+            *std*
+            Standard library for this test
+
+            Printed?
+            abc123
+            "#]],
+        );
+        check(
+            r#"
+//- /main.rs
+extern crate std as ab<|>c;
+//- /std/lib.rs
+//! Standard library for this test
+//!
+//! Printed?
+//! abc123
+            "#,
+            expect![[r#"
+            *abc*
+            Standard library for this test
+
+            Printed?
+            abc123
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_mod_with_same_name_as_function() {
+        check(
+            r#"
+use self::m<|>y::Bar;
+mod my { pub struct Bar; }
+
+fn my() {}
+"#,
+            expect![[r#"
+                *my*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                mod my
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_doc_comment() {
+        check(
+            r#"
+/// bar docs
+struct Bar;
+
+fn foo() { let bar = Ba<|>r; }
+"#,
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                struct Bar
+                ```
+
+                ---
+
+                bar docs
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_doc_attr() {
+        check(
+            r#"
+#[doc = "bar docs"]
+struct Bar;
+
+fn foo() { let bar = Ba<|>r; }
+"#,
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                struct Bar
+                ```
+
+                ---
+
+                bar docs
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_doc_attr_multiple_and_mixed() {
+        check(
+            r#"
+/// bar docs 0
+#[doc = "bar docs 1"]
+#[doc = "bar docs 2"]
+struct Bar;
+
+fn foo() { let bar = Ba<|>r; }
+"#,
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                struct Bar
+                ```
+
+                ---
+
+                bar docs 0
+
+                bar docs 1
+
+                bar docs 2
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_path_link() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [Foo](struct.Foo.html)
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_path_link_no_strip() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [struct Foo](struct.Foo.html)
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [struct Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[ignore = "path based links currently only support documentation on ModuleDef items"]
+    #[test]
+    fn test_hover_path_link_field() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            pub struct Bar {
+                /// [Foo](struct.Foo.html)
+                fie<|>ld: ()
+            }
+            ",
+            expect![[r#"
+                *field*
+
+                ```rust
+                test::Bar
+                ```
+
+                ```rust
+                field: ()
+                ```
+
+                ---
+
+                [Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link() {
+        check(
+            r"
+            //- /lib.rs
+            pub mod foo {
+                pub struct Foo;
+            }
+            /// [Foo](foo::Foo)
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [Foo](https://docs.rs/test/*/test/foo/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_html_root_url() {
+        check(
+            r#"
+            //- /lib.rs
+
+            #![doc(arbitrary_attribute = "test", html_root_url = "https:/example.com", arbitrary_attribute2)]
+
+            pub mod foo {
+                pub struct Foo;
+            }
+            /// [Foo](foo::Foo)
+            pub struct B<|>ar
+            "#,
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [Foo](https://example.com/test/foo/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_shortlink() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [Foo]
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_shortlink_code() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [`Foo`]
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [`Foo`](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_namespaced() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            fn Foo() {}
+            /// [Foo()]
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_shortlink_namspaced_code() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [`struct Foo`]
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [`Foo`](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_shortlink_namspaced_code_with_at() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [`struct@Foo`]
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [`Foo`](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_intra_link_reference() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [my Foo][foo]
+            ///
+            /// [foo]: Foo
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [my Foo](https://docs.rs/test/*/test/struct.Foo.html)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_external_url() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [external](https://www.google.com)
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [external](https://www.google.com)
+            "#]],
+        );
+    }
+
+    // Check that we don't rewrite links which we can't identify
+    #[test]
+    fn test_hover_unknown_target() {
+        check(
+            r"
+            //- /lib.rs
+            pub struct Foo;
+            /// [baz](Baz)
+            pub struct B<|>ar
+            ",
+            expect![[r#"
+                *Bar*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                pub struct Bar
+                ```
+
+                ---
+
+                [baz](Baz)
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_macro_generated_struct_fn_doc_comment() {
+        mark::check!(hover_macro_generated_struct_fn_doc_comment);
+
+        check(
+            r#"
+macro_rules! bar {
+    () => {
+        struct Bar;
+        impl Bar {
+            /// Do the foo
+            fn foo(&self) {}
+        }
+    }
+}
+
+bar!();
+
+fn foo() { let bar = Bar; bar.fo<|>o(); }
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test::Bar
+                ```
+
+                ```rust
+                fn foo(&self)
+                ```
+
+                ---
+
+                Do the foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_macro_generated_struct_fn_doc_attr() {
+        mark::check!(hover_macro_generated_struct_fn_doc_attr);
+
+        check(
+            r#"
+macro_rules! bar {
+    () => {
+        struct Bar;
+        impl Bar {
+            #[doc = "Do the foo"]
+            fn foo(&self) {}
+        }
+    }
+}
+
+bar!();
+
+fn foo() { let bar = Bar; bar.fo<|>o(); }
+"#,
+            expect![[r#"
+                *foo*
+
+                ```rust
+                test::Bar
+                ```
+
+                ```rust
+                fn foo(&self)
+                ```
+
+                ---
+
+                Do the foo
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_trait_has_impl_action() {
+        check_actions(
+            r#"trait foo<|>() {}"#,
+            expect![[r#"
+                [
+                    Implementaion(
+                        FilePosition {
+                            file_id: FileId(
+                                1,
+                            ),
+                            offset: 6,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_has_impl_action() {
+        check_actions(
+            r"struct foo<|>() {}",
+            expect![[r#"
+                [
+                    Implementaion(
+                        FilePosition {
+                            file_id: FileId(
+                                1,
+                            ),
+                            offset: 7,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_union_has_impl_action() {
+        check_actions(
+            r#"union foo<|>() {}"#,
+            expect![[r#"
+                [
+                    Implementaion(
+                        FilePosition {
+                            file_id: FileId(
+                                1,
+                            ),
+                            offset: 6,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_enum_has_impl_action() {
+        check_actions(
+            r"enum foo<|>() { A, B }",
+            expect![[r#"
+                [
+                    Implementaion(
+                        FilePosition {
+                            file_id: FileId(
+                                1,
+                            ),
+                            offset: 5,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_test_has_action() {
+        check_actions(
+            r#"
+#[test]
+fn foo_<|>test() {}
+"#,
+            expect![[r#"
+                [
+                    Runnable(
+                        Runnable {
+                            nav: NavigationTarget {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                full_range: 0..24,
+                                focus_range: Some(
+                                    11..19,
+                                ),
+                                name: "foo_test",
+                                kind: FN,
+                                container_name: None,
+                                description: None,
+                                docs: None,
+                            },
+                            kind: Test {
+                                test_id: Path(
+                                    "foo_test",
+                                ),
+                                attr: TestAttr {
+                                    ignore: false,
+                                },
+                            },
+                            cfg_exprs: [],
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_test_mod_has_action() {
+        check_actions(
+            r#"
+mod tests<|> {
+    #[test]
+    fn foo_test() {}
+}
+"#,
+            expect![[r#"
+                [
+                    Runnable(
+                        Runnable {
+                            nav: NavigationTarget {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                full_range: 0..46,
+                                focus_range: Some(
+                                    4..9,
+                                ),
+                                name: "tests",
+                                kind: MODULE,
+                                container_name: None,
+                                description: None,
+                                docs: None,
+                            },
+                            kind: TestMod {
+                                path: "tests",
+                            },
+                            cfg_exprs: [],
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_struct_has_goto_type_action() {
+        check_actions(
+            r#"
+struct S{ f1: u32 }
+
+fn main() { let s<|>t = S{ f1:0 }; }
+            "#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..19,
+                                    focus_range: Some(
+                                        7..8,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_generic_struct_has_goto_type_actions() {
+        check_actions(
+            r#"
+struct Arg(u32);
+struct S<T>{ f1: T }
+
+fn main() { let s<|>t = S{ f1:Arg(0) }; }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 17..37,
+                                    focus_range: Some(
+                                        24..25,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Arg",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..16,
+                                    focus_range: Some(
+                                        7..10,
+                                    ),
+                                    name: "Arg",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct Arg",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_generic_struct_has_flattened_goto_type_actions() {
+        check_actions(
+            r#"
+struct Arg(u32);
+struct S<T>{ f1: T }
+
+fn main() { let s<|>t = S{ f1: S{ f1: Arg(0) } }; }
+            "#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 17..37,
+                                    focus_range: Some(
+                                        24..25,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Arg",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..16,
+                                    focus_range: Some(
+                                        7..10,
+                                    ),
+                                    name: "Arg",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct Arg",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_tuple_has_goto_type_actions() {
+        check_actions(
+            r#"
+struct A(u32);
+struct B(u32);
+mod M {
+    pub struct C(u32);
+}
+
+fn main() { let s<|>t = (A(1), B(2), M::C(3) ); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::A",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..14,
+                                    focus_range: Some(
+                                        7..8,
+                                    ),
+                                    name: "A",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct A",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::B",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 15..29,
+                                    focus_range: Some(
+                                        22..23,
+                                    ),
+                                    name: "B",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct B",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::M::C",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 42..60,
+                                    focus_range: Some(
+                                        53..54,
+                                    ),
+                                    name: "C",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "pub struct C",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_return_impl_trait_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+fn foo() -> impl Foo {}
+
+fn main() { let s<|>t = foo(); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_generic_return_impl_trait_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo<T> {}
+struct S;
+fn foo() -> impl Foo<S> {}
+
+fn main() { let s<|>t = foo(); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..15,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 16..25,
+                                    focus_range: Some(
+                                        23..24,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_return_impl_traits_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+trait Bar {}
+fn foo() -> impl Foo + Bar {}
+
+fn main() { let s<|>t = foo(); }
+            "#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Bar",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 13..25,
+                                    focus_range: Some(
+                                        19..22,
+                                    ),
+                                    name: "Bar",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Bar",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_generic_return_impl_traits_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo<T> {}
+trait Bar<T> {}
+struct S1 {}
+struct S2 {}
+
+fn foo() -> impl Foo<S1> + Bar<S2> {}
+
+fn main() { let s<|>t = foo(); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..15,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Bar",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 16..31,
+                                    focus_range: Some(
+                                        22..25,
+                                    ),
+                                    name: "Bar",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Bar",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S1",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 32..44,
+                                    focus_range: Some(
+                                        39..41,
+                                    ),
+                                    name: "S1",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S1",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S2",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 45..57,
+                                    focus_range: Some(
+                                        52..54,
+                                    ),
+                                    name: "S2",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S2",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_arg_impl_trait_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+fn foo(ar<|>g: &impl Foo) {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_arg_impl_traits_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+trait Bar<T> {}
+struct S{}
+
+fn foo(ar<|>g: &impl Foo + Bar<S>) {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Bar",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 13..28,
+                                    focus_range: Some(
+                                        19..22,
+                                    ),
+                                    name: "Bar",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Bar",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 29..39,
+                                    focus_range: Some(
+                                        36..37,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_arg_generic_impl_trait_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo<T> {}
+struct S {}
+fn foo(ar<|>g: &impl Foo<S>) {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..15,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 16..27,
+                                    focus_range: Some(
+                                        23..24,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_dyn_return_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+struct S;
+impl Foo for S {}
+
+struct B<T>{}
+fn foo() -> B<dyn Foo> {}
+
+fn main() { let s<|>t = foo(); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::B",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 42..55,
+                                    focus_range: Some(
+                                        49..50,
+                                    ),
+                                    name: "B",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct B",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_dyn_arg_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+fn foo(ar<|>g: &dyn Foo) {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_generic_dyn_arg_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo<T> {}
+struct S {}
+fn foo(ar<|>g: &dyn Foo<S>) {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..15,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 16..27,
+                                    focus_range: Some(
+                                        23..24,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_goto_type_action_links_order() {
+        check_actions(
+            r#"
+trait ImplTrait<T> {}
+trait DynTrait<T> {}
+struct B<T> {}
+struct S {}
+
+fn foo(a<|>rg: &impl ImplTrait<B<dyn DynTrait<B<S>>>>) {}
+            "#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::ImplTrait",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..21,
+                                    focus_range: Some(
+                                        6..15,
+                                    ),
+                                    name: "ImplTrait",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait ImplTrait",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::B",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 43..57,
+                                    focus_range: Some(
+                                        50..51,
+                                    ),
+                                    name: "B",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct B",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::DynTrait",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 22..42,
+                                    focus_range: Some(
+                                        28..36,
+                                    ),
+                                    name: "DynTrait",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait DynTrait",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                            HoverGotoTypeData {
+                                mod_path: "test::S",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 58..69,
+                                    focus_range: Some(
+                                        65..66,
+                                    ),
+                                    name: "S",
+                                    kind: STRUCT,
+                                    container_name: None,
+                                    description: Some(
+                                        "struct S",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_associated_type_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {
+    type Item;
+    fn get(self) -> Self::Item {}
+}
+
+struct Bar{}
+struct S{}
+
+impl Foo for S { type Item = Bar; }
+
+fn test() -> impl Foo { S {} }
+
+fn main() { let s<|>t = test().get(); }
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        1,
+                                    ),
+                                    full_range: 0..62,
+                                    focus_range: Some(
+                                        6..9,
+                                    ),
+                                    name: "Foo",
+                                    kind: TRAIT,
+                                    container_name: None,
+                                    description: Some(
+                                        "trait Foo",
+                                    ),
+                                    docs: None,
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
new file mode 100644
index 000000000..583f39d85
--- /dev/null
+++ b/crates/ide/src/inlay_hints.rs
@@ -0,0 +1,927 @@
+use hir::{Adt, Callable, HirDisplay, Semantics, Type};
+use ide_db::RootDatabase;
+use stdx::to_lower_snake_case;
+use syntax::{
+    ast::{self, ArgListOwner, AstNode},
+    match_ast, Direction, NodeOrToken, SmolStr, SyntaxKind, TextRange, T,
+};
+
+use crate::FileId;
+use ast::NameOwner;
+use either::Either;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct InlayHintsConfig {
+    pub type_hints: bool,
+    pub parameter_hints: bool,
+    pub chaining_hints: bool,
+    pub max_length: Option<usize>,
+}
+
+impl Default for InlayHintsConfig {
+    fn default() -> Self {
+        Self { type_hints: true, parameter_hints: true, chaining_hints: true, max_length: None }
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum InlayKind {
+    TypeHint,
+    ParameterHint,
+    ChainingHint,
+}
+
+#[derive(Debug)]
+pub struct InlayHint {
+    pub range: TextRange,
+    pub kind: InlayKind,
+    pub label: SmolStr,
+}
+
+// Feature: Inlay Hints
+//
+// rust-analyzer shows additional information inline with the source code.
+// Editors usually render this using read-only virtual text snippets interspersed with code.
+//
+// rust-analyzer shows hints for
+//
+// * types of local variables
+// * names of function arguments
+// * types of chained expressions
+//
+// **Note:** VS Code does not have native support for inlay hints https://github.com/microsoft/vscode/issues/16221[yet] and the hints are implemented using decorations.
+// This approach has limitations, the caret movement and bracket highlighting near the edges of the hint may be weird:
+// https://github.com/rust-analyzer/rust-analyzer/issues/1623[1], https://github.com/rust-analyzer/rust-analyzer/issues/3453[2].
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Toggle inlay hints*
+// |===
+pub(crate) fn inlay_hints(
+    db: &RootDatabase,
+    file_id: FileId,
+    config: &InlayHintsConfig,
+) -> Vec<InlayHint> {
+    let _p = profile::span("inlay_hints");
+    let sema = Semantics::new(db);
+    let file = sema.parse(file_id);
+
+    let mut res = Vec::new();
+    for node in file.syntax().descendants() {
+        if let Some(expr) = ast::Expr::cast(node.clone()) {
+            get_chaining_hints(&mut res, &sema, config, expr);
+        }
+
+        match_ast! {
+            match node {
+                ast::CallExpr(it) => { get_param_name_hints(&mut res, &sema, config, ast::Expr::from(it)); },
+                ast::MethodCallExpr(it) => { get_param_name_hints(&mut res, &sema, config, ast::Expr::from(it)); },
+                ast::IdentPat(it) => { get_bind_pat_hints(&mut res, &sema, config, it); },
+                _ => (),
+            }
+        }
+    }
+    res
+}
+
+fn get_chaining_hints(
+    acc: &mut Vec<InlayHint>,
+    sema: &Semantics<RootDatabase>,
+    config: &InlayHintsConfig,
+    expr: ast::Expr,
+) -> Option<()> {
+    if !config.chaining_hints {
+        return None;
+    }
+
+    if matches!(expr, ast::Expr::RecordExpr(_)) {
+        return None;
+    }
+
+    let mut tokens = expr
+        .syntax()
+        .siblings_with_tokens(Direction::Next)
+        .filter_map(NodeOrToken::into_token)
+        .filter(|t| match t.kind() {
+            SyntaxKind::WHITESPACE if !t.text().contains('\n') => false,
+            SyntaxKind::COMMENT => false,
+            _ => true,
+        });
+
+    // Chaining can be defined as an expression whose next sibling tokens are newline and dot
+    // Ignoring extra whitespace and comments
+    let next = tokens.next()?.kind();
+    let next_next = tokens.next()?.kind();
+    if next == SyntaxKind::WHITESPACE && next_next == T![.] {
+        let ty = sema.type_of_expr(&expr)?;
+        if ty.is_unknown() {
+            return None;
+        }
+        if matches!(expr, ast::Expr::PathExpr(_)) {
+            if let Some(Adt::Struct(st)) = ty.as_adt() {
+                if st.fields(sema.db).is_empty() {
+                    return None;
+                }
+            }
+        }
+        let label = ty.display_truncated(sema.db, config.max_length).to_string();
+        acc.push(InlayHint {
+            range: expr.syntax().text_range(),
+            kind: InlayKind::ChainingHint,
+            label: label.into(),
+        });
+    }
+    Some(())
+}
+
+fn get_param_name_hints(
+    acc: &mut Vec<InlayHint>,
+    sema: &Semantics<RootDatabase>,
+    config: &InlayHintsConfig,
+    expr: ast::Expr,
+) -> Option<()> {
+    if !config.parameter_hints {
+        return None;
+    }
+
+    let args = match &expr {
+        ast::Expr::CallExpr(expr) => expr.arg_list()?.args(),
+        ast::Expr::MethodCallExpr(expr) => expr.arg_list()?.args(),
+        _ => return None,
+    };
+
+    let callable = get_callable(sema, &expr)?;
+    let hints = callable
+        .params(sema.db)
+        .into_iter()
+        .zip(args)
+        .filter_map(|((param, _ty), arg)| {
+            let param_name = match param? {
+                Either::Left(self_param) => self_param.to_string(),
+                Either::Right(pat) => match pat {
+                    ast::Pat::IdentPat(it) => it.name()?.to_string(),
+                    _ => return None,
+                },
+            };
+            Some((param_name, arg))
+        })
+        .filter(|(param_name, arg)| should_show_param_name_hint(sema, &callable, &param_name, &arg))
+        .map(|(param_name, arg)| InlayHint {
+            range: arg.syntax().text_range(),
+            kind: InlayKind::ParameterHint,
+            label: param_name.into(),
+        });
+
+    acc.extend(hints);
+    Some(())
+}
+
+fn get_bind_pat_hints(
+    acc: &mut Vec<InlayHint>,
+    sema: &Semantics<RootDatabase>,
+    config: &InlayHintsConfig,
+    pat: ast::IdentPat,
+) -> Option<()> {
+    if !config.type_hints {
+        return None;
+    }
+
+    let ty = sema.type_of_pat(&pat.clone().into())?;
+
+    if should_not_display_type_hint(sema.db, &pat, &ty) {
+        return None;
+    }
+
+    acc.push(InlayHint {
+        range: pat.syntax().text_range(),
+        kind: InlayKind::TypeHint,
+        label: ty.display_truncated(sema.db, config.max_length).to_string().into(),
+    });
+    Some(())
+}
+
+fn pat_is_enum_variant(db: &RootDatabase, bind_pat: &ast::IdentPat, pat_ty: &Type) -> bool {
+    if let Some(Adt::Enum(enum_data)) = pat_ty.as_adt() {
+        let pat_text = bind_pat.to_string();
+        enum_data
+            .variants(db)
+            .into_iter()
+            .map(|variant| variant.name(db).to_string())
+            .any(|enum_name| enum_name == pat_text)
+    } else {
+        false
+    }
+}
+
+fn should_not_display_type_hint(
+    db: &RootDatabase,
+    bind_pat: &ast::IdentPat,
+    pat_ty: &Type,
+) -> bool {
+    if pat_ty.is_unknown() {
+        return true;
+    }
+
+    if let Some(Adt::Struct(s)) = pat_ty.as_adt() {
+        if s.fields(db).is_empty() && s.name(db).to_string() == bind_pat.to_string() {
+            return true;
+        }
+    }
+
+    for node in bind_pat.syntax().ancestors() {
+        match_ast! {
+            match node {
+                ast::LetStmt(it) => {
+                    return it.ty().is_some()
+                },
+                ast::Param(it) => {
+                    return it.ty().is_some()
+                },
+                ast::MatchArm(_it) => {
+                    return pat_is_enum_variant(db, bind_pat, pat_ty);
+                },
+                ast::IfExpr(it) => {
+                    return it.condition().and_then(|condition| condition.pat()).is_some()
+                        && pat_is_enum_variant(db, bind_pat, pat_ty);
+                },
+                ast::WhileExpr(it) => {
+                    return it.condition().and_then(|condition| condition.pat()).is_some()
+                        && pat_is_enum_variant(db, bind_pat, pat_ty);
+                },
+                _ => (),
+            }
+        }
+    }
+    false
+}
+
+fn should_show_param_name_hint(
+    sema: &Semantics<RootDatabase>,
+    callable: &Callable,
+    param_name: &str,
+    argument: &ast::Expr,
+) -> bool {
+    let param_name = param_name.trim_start_matches('_');
+    let fn_name = match callable.kind() {
+        hir::CallableKind::Function(it) => Some(it.name(sema.db).to_string()),
+        hir::CallableKind::TupleStruct(_)
+        | hir::CallableKind::TupleEnumVariant(_)
+        | hir::CallableKind::Closure => None,
+    };
+    if param_name.is_empty()
+        || Some(param_name) == fn_name.as_ref().map(|s| s.trim_start_matches('_'))
+        || is_argument_similar_to_param_name(sema, argument, param_name)
+        || param_name.starts_with("ra_fixture")
+    {
+        return false;
+    }
+
+    // avoid displaying hints for common functions like map, filter, etc.
+    // or other obvious words used in std
+    !(callable.n_params() == 1 && is_obvious_param(param_name))
+}
+
+fn is_argument_similar_to_param_name(
+    sema: &Semantics<RootDatabase>,
+    argument: &ast::Expr,
+    param_name: &str,
+) -> bool {
+    if is_enum_name_similar_to_param_name(sema, argument, param_name) {
+        return true;
+    }
+    match get_string_representation(argument) {
+        None => false,
+        Some(repr) => {
+            let argument_string = repr.trim_start_matches('_');
+            argument_string.starts_with(param_name) || argument_string.ends_with(param_name)
+        }
+    }
+}
+
+fn is_enum_name_similar_to_param_name(
+    sema: &Semantics<RootDatabase>,
+    argument: &ast::Expr,
+    param_name: &str,
+) -> bool {
+    match sema.type_of_expr(argument).and_then(|t| t.as_adt()) {
+        Some(Adt::Enum(e)) => to_lower_snake_case(&e.name(sema.db).to_string()) == param_name,
+        _ => false,
+    }
+}
+
+fn get_string_representation(expr: &ast::Expr) -> Option<String> {
+    match expr {
+        ast::Expr::MethodCallExpr(method_call_expr) => {
+            Some(method_call_expr.name_ref()?.to_string())
+        }
+        ast::Expr::RefExpr(ref_expr) => get_string_representation(&ref_expr.expr()?),
+        _ => Some(expr.to_string()),
+    }
+}
+
+fn is_obvious_param(param_name: &str) -> bool {
+    let is_obvious_param_name =
+        matches!(param_name, "predicate" | "value" | "pat" | "rhs" | "other");
+    param_name.len() == 1 || is_obvious_param_name
+}
+
+fn get_callable(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Option<Callable> {
+    match expr {
+        ast::Expr::CallExpr(expr) => sema.type_of_expr(&expr.expr()?)?.as_callable(sema.db),
+        ast::Expr::MethodCallExpr(expr) => sema.resolve_method_call_as_callable(expr),
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use test_utils::extract_annotations;
+
+    use crate::{inlay_hints::InlayHintsConfig, mock_analysis::single_file};
+
+    fn check(ra_fixture: &str) {
+        check_with_config(InlayHintsConfig::default(), ra_fixture);
+    }
+
+    fn check_with_config(config: InlayHintsConfig, ra_fixture: &str) {
+        let (analysis, file_id) = single_file(ra_fixture);
+        let expected = extract_annotations(&*analysis.file_text(file_id).unwrap());
+        let inlay_hints = analysis.inlay_hints(file_id, &config).unwrap();
+        let actual =
+            inlay_hints.into_iter().map(|it| (it.range, it.label.to_string())).collect::<Vec<_>>();
+        assert_eq!(expected, actual, "\nExpected:\n{:#?}\n\nActual:\n{:#?}", expected, actual);
+    }
+
+    fn check_expect(config: InlayHintsConfig, ra_fixture: &str, expect: Expect) {
+        let (analysis, file_id) = single_file(ra_fixture);
+        let inlay_hints = analysis.inlay_hints(file_id, &config).unwrap();
+        expect.assert_debug_eq(&inlay_hints)
+    }
+
+    #[test]
+    fn param_hints_only() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: true,
+                type_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn foo(a: i32, b: i32) -> i32 { a + b }
+fn main() {
+    let _x = foo(
+        4,
+      //^ a
+        4,
+      //^ b
+    );
+}"#,
+        );
+    }
+
+    #[test]
+    fn hints_disabled() {
+        check_with_config(
+            InlayHintsConfig {
+                type_hints: false,
+                parameter_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn foo(a: i32, b: i32) -> i32 { a + b }
+fn main() {
+    let _x = foo(4, 4);
+}"#,
+        );
+    }
+
+    #[test]
+    fn type_hints_only() {
+        check_with_config(
+            InlayHintsConfig {
+                type_hints: true,
+                parameter_hints: false,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+fn foo(a: i32, b: i32) -> i32 { a + b }
+fn main() {
+    let _x = foo(4, 4);
+      //^^ i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn default_generic_types_should_not_be_displayed() {
+        check(
+            r#"
+struct Test<K, T = u8> { k: K, t: T }
+
+fn main() {
+    let zz = Test { t: 23u8, k: 33 };
+      //^^ Test<i32>
+    let zz_ref = &zz;
+      //^^^^^^ &Test<i32>
+    let test = || zz;
+      //^^^^ || -> Test<i32>
+}"#,
+        );
+    }
+
+    #[test]
+    fn let_statement() {
+        check(
+            r#"
+#[derive(PartialEq)]
+enum Option<T> { None, Some(T) }
+
+#[derive(PartialEq)]
+struct Test { a: Option<u32>, b: u8 }
+
+fn main() {
+    struct InnerStruct {}
+
+    let test = 54;
+      //^^^^ i32
+    let test: i32 = 33;
+    let mut test = 33;
+      //^^^^^^^^ i32
+    let _ = 22;
+    let test = "test";
+      //^^^^ &str
+    let test = InnerStruct {};
+
+    let test = unresolved();
+
+    let test = (42, 'a');
+      //^^^^ (i32, char)
+    let (a,    (b,     (c,)) = (2, (3, (9.2,));
+       //^ i32  ^ i32   ^ f64
+    let &x = &92;
+       //^ i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn closure_parameters() {
+        check(
+            r#"
+fn main() {
+    let mut start = 0;
+      //^^^^^^^^^ i32
+    (0..2).for_each(|increment| { start += increment; });
+                   //^^^^^^^^^ i32
+
+    let multiply =
+      //^^^^^^^^ |…| -> i32
+      | a,     b| a * b
+      //^ i32  ^ i32
+    ;
+
+    let _: i32 = multiply(1, 2);
+    let multiply_ref = &multiply;
+      //^^^^^^^^^^^^ &|…| -> i32
+
+    let return_42 = || 42;
+      //^^^^^^^^^ || -> i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn for_expression() {
+        check(
+            r#"
+fn main() {
+    let mut start = 0;
+      //^^^^^^^^^ i32
+    for increment in 0..2 { start += increment; }
+      //^^^^^^^^^ i32
+}"#,
+        );
+    }
+
+    #[test]
+    fn if_expr() {
+        check(
+            r#"
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct Test { a: Option<u32>, b: u8 }
+
+fn main() {
+    let test = Some(Test { a: Some(3), b: 1 });
+      //^^^^ Option<Test>
+    if let None = &test {};
+    if let test = &test {};
+         //^^^^ &Option<Test>
+    if let Some(test) = &test {};
+              //^^^^ &Test
+    if let Some(Test { a,             b }) = &test {};
+                     //^ &Option<u32> ^ &u8
+    if let Some(Test { a: x,             b: y }) = &test {};
+                        //^ &Option<u32>    ^ &u8
+    if let Some(Test { a: Some(x),  b: y }) = &test {};
+                             //^ &u32  ^ &u8
+    if let Some(Test { a: None,  b: y }) = &test {};
+                                  //^ &u8
+    if let Some(Test { b: y, .. }) = &test {};
+                        //^ &u8
+    if test == None {}
+}"#,
+        );
+    }
+
+    #[test]
+    fn while_expr() {
+        check(
+            r#"
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct Test { a: Option<u32>, b: u8 }
+
+fn main() {
+    let test = Some(Test { a: Some(3), b: 1 });
+      //^^^^ Option<Test>
+    while let Some(Test { a: Some(x),  b: y }) = &test {};
+                                //^ &u32  ^ &u8
+}"#,
+        );
+    }
+
+    #[test]
+    fn match_arm_list() {
+        check(
+            r#"
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct Test { a: Option<u32>, b: u8 }
+
+fn main() {
+    match Some(Test { a: Some(3), b: 1 }) {
+        None => (),
+        test => (),
+      //^^^^ Option<Test>
+        Some(Test { a: Some(x), b: y }) => (),
+                          //^ u32  ^ u8
+        _ => {}
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn hint_truncation() {
+        check_with_config(
+            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            r#"
+struct Smol<T>(T);
+
+struct VeryLongOuterName<T>(T);
+
+fn main() {
+    let a = Smol(0u32);
+      //^ Smol<u32>
+    let b = VeryLongOuterName(0usize);
+      //^ VeryLongOuterName<…>
+    let c = Smol(Smol(0u32))
+      //^ Smol<Smol<…>>
+}"#,
+        );
+    }
+
+    #[test]
+    fn function_call_parameter_hint() {
+        check(
+            r#"
+enum Option<T> { None, Some(T) }
+use Option::*;
+
+struct FileId {}
+struct SmolStr {}
+
+struct TextRange {}
+struct SyntaxKind {}
+struct NavigationTarget {}
+
+struct Test {}
+
+impl Test {
+    fn method(&self, mut param: i32) -> i32 { param * 2 }
+
+    fn from_syntax(
+        file_id: FileId,
+        name: SmolStr,
+        focus_range: Option<TextRange>,
+        full_range: TextRange,
+        kind: SyntaxKind,
+        docs: Option<String>,
+    ) -> NavigationTarget {
+        NavigationTarget {}
+    }
+}
+
+fn test_func(mut foo: i32, bar: i32, msg: &str, _: i32, last: i32) -> i32 {
+    foo + bar
+}
+
+fn main() {
+    let not_literal = 1;
+      //^^^^^^^^^^^ i32
+    let _: i32 = test_func(1,    2,      "hello", 3,  not_literal);
+                         //^ foo ^ bar   ^^^^^^^ msg  ^^^^^^^^^^^ last
+    let t: Test = Test {};
+    t.method(123);
+           //^^^ param
+    Test::method(&t,      3456);
+               //^^ &self ^^^^ param
+    Test::from_syntax(
+        FileId {},
+      //^^^^^^^^^ file_id
+        "impl".into(),
+      //^^^^^^^^^^^^^ name
+        None,
+      //^^^^ focus_range
+        TextRange {},
+      //^^^^^^^^^^^^ full_range
+        SyntaxKind {},
+      //^^^^^^^^^^^^^ kind
+        None,
+      //^^^^ docs
+    );
+}"#,
+        );
+    }
+
+    #[test]
+    fn omitted_parameters_hints_heuristics() {
+        check_with_config(
+            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            r#"
+fn map(f: i32) {}
+fn filter(predicate: i32) {}
+
+struct TestVarContainer {
+    test_var: i32,
+}
+
+impl TestVarContainer {
+    fn test_var(&self) -> i32 {
+        self.test_var
+    }
+}
+
+struct Test {}
+
+impl Test {
+    fn map(self, f: i32) -> Self {
+        self
+    }
+
+    fn filter(self, predicate: i32) -> Self {
+        self
+    }
+
+    fn field(self, value: i32) -> Self {
+        self
+    }
+
+    fn no_hints_expected(&self, _: i32, test_var: i32) {}
+
+    fn frob(&self, frob: bool) {}
+}
+
+struct Param {}
+
+fn different_order(param: &Param) {}
+fn different_order_mut(param: &mut Param) {}
+fn has_underscore(_param: bool) {}
+fn enum_matches_param_name(completion_kind: CompletionKind) {}
+fn param_destructuring_omitted_1((a, b): (u32, u32)) {}
+fn param_destructuring_omitted_2(TestVarContainer { test_var: _ }: TestVarContainer) {}
+
+fn twiddle(twiddle: bool) {}
+fn doo(_doo: bool) {}
+
+enum CompletionKind {
+    Keyword,
+}
+
+fn main() {
+    let container: TestVarContainer = TestVarContainer { test_var: 42 };
+    let test: Test = Test {};
+
+    map(22);
+    filter(33);
+
+    let test_processed: Test = test.map(1).filter(2).field(3);
+
+    let test_var: i32 = 55;
+    test_processed.no_hints_expected(22, test_var);
+    test_processed.no_hints_expected(33, container.test_var);
+    test_processed.no_hints_expected(44, container.test_var());
+    test_processed.frob(false);
+
+    twiddle(true);
+    doo(true);
+
+    let mut param_begin: Param = Param {};
+    different_order(&param_begin);
+    different_order(&mut param_begin);
+
+    let param: bool = true;
+    has_underscore(param);
+
+    enum_matches_param_name(CompletionKind::Keyword);
+
+    let a: f64 = 7.0;
+    let b: f64 = 4.0;
+    let _: f64 = a.div_euclid(b);
+    let _: f64 = a.abs_sub(b);
+
+    let range: (u32, u32) = (3, 5);
+    param_destructuring_omitted_1(range);
+    param_destructuring_omitted_2(container);
+}"#,
+        );
+    }
+
+    #[test]
+    fn unit_structs_have_no_type_hints() {
+        check_with_config(
+            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+struct SyntheticSyntax;
+
+fn main() {
+    match Ok(()) {
+        Ok(_) => (),
+        Err(SyntheticSyntax) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn chaining_hints_ignore_comments() {
+        check_expect(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
+            r#"
+struct A(B);
+impl A { fn into_b(self) -> B { self.0 } }
+struct B(C);
+impl B { fn into_c(self) -> C { self.0 } }
+struct C;
+
+fn main() {
+    let c = A(B(C))
+        .into_b() // This is a comment
+        .into_c();
+}
+"#,
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 147..172,
+                        kind: ChainingHint,
+                        label: "B",
+                    },
+                    InlayHint {
+                        range: 147..154,
+                        kind: ChainingHint,
+                        label: "A",
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn chaining_hints_without_newlines() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
+            r#"
+struct A(B);
+impl A { fn into_b(self) -> B { self.0 } }
+struct B(C);
+impl B { fn into_c(self) -> C { self.0 } }
+struct C;
+
+fn main() {
+    let c = A(B(C)).into_b().into_c();
+}"#,
+        );
+    }
+
+    #[test]
+    fn struct_access_chaining_hints() {
+        check_expect(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
+            r#"
+struct A { pub b: B }
+struct B { pub c: C }
+struct C(pub bool);
+struct D;
+
+impl D {
+    fn foo(&self) -> i32 { 42 }
+}
+
+fn main() {
+    let x = A { b: B { c: C(true) } }
+        .b
+        .c
+        .0;
+    let x = D
+        .foo();
+}"#,
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 143..190,
+                        kind: ChainingHint,
+                        label: "C",
+                    },
+                    InlayHint {
+                        range: 143..179,
+                        kind: ChainingHint,
+                        label: "B",
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn generic_chaining_hints() {
+        check_expect(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: false,
+                chaining_hints: true,
+                max_length: None,
+            },
+            r#"
+struct A<T>(T);
+struct B<T>(T);
+struct C<T>(T);
+struct X<T,R>(T, R);
+
+impl<T> A<T> {
+    fn new(t: T) -> Self { A(t) }
+    fn into_b(self) -> B<T> { B(self.0) }
+}
+impl<T> B<T> {
+    fn into_c(self) -> C<T> { C(self.0) }
+}
+fn main() {
+    let c = A::new(X(42, true))
+        .into_b()
+        .into_c();
+}
+"#,
+            expect![[r#"
+                [
+                    InlayHint {
+                        range: 246..283,
+                        kind: ChainingHint,
+                        label: "B<X<i32, bool>>",
+                    },
+                    InlayHint {
+                        range: 246..265,
+                        kind: ChainingHint,
+                        label: "A<X<i32, bool>>",
+                    },
+                ]
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/join_lines.rs b/crates/ide/src/join_lines.rs
new file mode 100644
index 000000000..e37702acd
--- /dev/null
+++ b/crates/ide/src/join_lines.rs
@@ -0,0 +1,773 @@
+use assists::utils::extract_trivial_expression;
+use itertools::Itertools;
+use syntax::{
+    algo::{find_covering_element, non_trivia_sibling},
+    ast::{self, AstNode, AstToken},
+    Direction, NodeOrToken, SourceFile,
+    SyntaxKind::{self, USE_TREE, WHITESPACE},
+    SyntaxNode, SyntaxToken, TextRange, TextSize, T,
+};
+use text_edit::{TextEdit, TextEditBuilder};
+
+// Feature: Join Lines
+//
+// Join selected lines into one, smartly fixing up whitespace, trailing commas, and braces.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Join lines**
+// |===
+pub fn join_lines(file: &SourceFile, range: TextRange) -> TextEdit {
+    let range = if range.is_empty() {
+        let syntax = file.syntax();
+        let text = syntax.text().slice(range.start()..);
+        let pos = match text.find_char('\n') {
+            None => return TextEdit::builder().finish(),
+            Some(pos) => pos,
+        };
+        TextRange::at(range.start() + pos, TextSize::of('\n'))
+    } else {
+        range
+    };
+
+    let node = match find_covering_element(file.syntax(), range) {
+        NodeOrToken::Node(node) => node,
+        NodeOrToken::Token(token) => token.parent(),
+    };
+    let mut edit = TextEdit::builder();
+    for token in node.descendants_with_tokens().filter_map(|it| it.into_token()) {
+        let range = match range.intersect(token.text_range()) {
+            Some(range) => range,
+            None => continue,
+        } - token.text_range().start();
+        let text = token.text();
+        for (pos, _) in text[range].bytes().enumerate().filter(|&(_, b)| b == b'\n') {
+            let pos: TextSize = (pos as u32).into();
+            let off = token.text_range().start() + range.start() + pos;
+            if !edit.invalidates_offset(off) {
+                remove_newline(&mut edit, &token, off);
+            }
+        }
+    }
+
+    edit.finish()
+}
+
+fn remove_newline(edit: &mut TextEditBuilder, token: &SyntaxToken, offset: TextSize) {
+    if token.kind() != WHITESPACE || token.text().bytes().filter(|&b| b == b'\n').count() != 1 {
+        // The node is either the first or the last in the file
+        let suff = &token.text()[TextRange::new(
+            offset - token.text_range().start() + TextSize::of('\n'),
+            TextSize::of(token.text().as_str()),
+        )];
+        let spaces = suff.bytes().take_while(|&b| b == b' ').count();
+
+        edit.replace(TextRange::at(offset, ((spaces + 1) as u32).into()), " ".to_string());
+        return;
+    }
+
+    // The node is between two other nodes
+    let prev = token.prev_sibling_or_token().unwrap();
+    let next = token.next_sibling_or_token().unwrap();
+    if is_trailing_comma(prev.kind(), next.kind()) {
+        // Removes: trailing comma, newline (incl. surrounding whitespace)
+        edit.delete(TextRange::new(prev.text_range().start(), token.text_range().end()));
+        return;
+    }
+    if prev.kind() == T![,] && next.kind() == T!['}'] {
+        // Removes: comma, newline (incl. surrounding whitespace)
+        let space = if let Some(left) = prev.prev_sibling_or_token() {
+            compute_ws(left.kind(), next.kind())
+        } else {
+            " "
+        };
+        edit.replace(
+            TextRange::new(prev.text_range().start(), token.text_range().end()),
+            space.to_string(),
+        );
+        return;
+    }
+
+    if let (Some(_), Some(next)) = (
+        prev.as_token().cloned().and_then(ast::Comment::cast),
+        next.as_token().cloned().and_then(ast::Comment::cast),
+    ) {
+        // Removes: newline (incl. surrounding whitespace), start of the next comment
+        edit.delete(TextRange::new(
+            token.text_range().start(),
+            next.syntax().text_range().start() + TextSize::of(next.prefix()),
+        ));
+        return;
+    }
+
+    // Special case that turns something like:
+    //
+    // ```
+    // my_function({<|>
+    //    <some-expr>
+    // })
+    // ```
+    //
+    // into `my_function(<some-expr>)`
+    if join_single_expr_block(edit, token).is_some() {
+        return;
+    }
+    // ditto for
+    //
+    // ```
+    // use foo::{<|>
+    //    bar
+    // };
+    // ```
+    if join_single_use_tree(edit, token).is_some() {
+        return;
+    }
+
+    // Remove newline but add a computed amount of whitespace characters
+    edit.replace(token.text_range(), compute_ws(prev.kind(), next.kind()).to_string());
+}
+
+fn has_comma_after(node: &SyntaxNode) -> bool {
+    match non_trivia_sibling(node.clone().into(), Direction::Next) {
+        Some(n) => n.kind() == T![,],
+        _ => false,
+    }
+}
+
+fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
+    let block_expr = ast::BlockExpr::cast(token.parent())?;
+    if !block_expr.is_standalone() {
+        return None;
+    }
+    let expr = extract_trivial_expression(&block_expr)?;
+
+    let block_range = block_expr.syntax().text_range();
+    let mut buf = expr.syntax().text().to_string();
+
+    // Match block needs to have a comma after the block
+    if let Some(match_arm) = block_expr.syntax().parent().and_then(ast::MatchArm::cast) {
+        if !has_comma_after(match_arm.syntax()) {
+            buf.push(',');
+        }
+    }
+
+    edit.replace(block_range, buf);
+
+    Some(())
+}
+
+fn join_single_use_tree(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
+    let use_tree_list = ast::UseTreeList::cast(token.parent())?;
+    let (tree,) = use_tree_list.use_trees().collect_tuple()?;
+    edit.replace(use_tree_list.syntax().text_range(), tree.syntax().text().to_string());
+    Some(())
+}
+
+fn is_trailing_comma(left: SyntaxKind, right: SyntaxKind) -> bool {
+    matches!((left, right), (T![,], T![')']) | (T![,], T![']']))
+}
+
+fn compute_ws(left: SyntaxKind, right: SyntaxKind) -> &'static str {
+    match left {
+        T!['('] | T!['['] => return "",
+        T!['{'] => {
+            if let USE_TREE = right {
+                return "";
+            }
+        }
+        _ => (),
+    }
+    match right {
+        T![')'] | T![']'] => return "",
+        T!['}'] => {
+            if let USE_TREE = left {
+                return "";
+            }
+        }
+        T![.] => return "",
+        _ => (),
+    }
+    " "
+}
+
+#[cfg(test)]
+mod tests {
+    use syntax::SourceFile;
+    use test_utils::{add_cursor, assert_eq_text, extract_offset, extract_range};
+
+    use super::*;
+
+    fn check_join_lines(before: &str, after: &str) {
+        let (before_cursor_pos, before) = extract_offset(before);
+        let file = SourceFile::parse(&before).ok().unwrap();
+
+        let range = TextRange::empty(before_cursor_pos);
+        let result = join_lines(&file, range);
+
+        let actual = {
+            let mut actual = before.to_string();
+            result.apply(&mut actual);
+            actual
+        };
+        let actual_cursor_pos = result
+            .apply_to_offset(before_cursor_pos)
+            .expect("cursor position is affected by the edit");
+        let actual = add_cursor(&actual, actual_cursor_pos);
+        assert_eq_text!(after, &actual);
+    }
+
+    #[test]
+    fn test_join_lines_comma() {
+        check_join_lines(
+            r"
+fn foo() {
+    <|>foo(1,
+    )
+}
+",
+            r"
+fn foo() {
+    <|>foo(1)
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_lambda_block() {
+        check_join_lines(
+            r"
+pub fn reparse(&self, edit: &AtomTextEdit) -> File {
+    <|>self.incremental_reparse(edit).unwrap_or_else(|| {
+        self.full_reparse(edit)
+    })
+}
+",
+            r"
+pub fn reparse(&self, edit: &AtomTextEdit) -> File {
+    <|>self.incremental_reparse(edit).unwrap_or_else(|| self.full_reparse(edit))
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_block() {
+        check_join_lines(
+            r"
+fn foo() {
+    foo(<|>{
+        92
+    })
+}",
+            r"
+fn foo() {
+    foo(<|>92)
+}",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_diverging_block() {
+        let before = r"
+            fn foo() {
+                loop {
+                    match x {
+                        92 => <|>{
+                            continue;
+                        }
+                    }
+                }
+            }
+        ";
+        let after = r"
+            fn foo() {
+                loop {
+                    match x {
+                        92 => <|>continue,
+                    }
+                }
+            }
+        ";
+        check_join_lines(before, after);
+    }
+
+    #[test]
+    fn join_lines_adds_comma_for_block_in_match_arm() {
+        check_join_lines(
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>{
+            u.foo()
+        }
+        Err(v) => v,
+    }
+}",
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>u.foo(),
+        Err(v) => v,
+    }
+}",
+        );
+    }
+
+    #[test]
+    fn join_lines_multiline_in_block() {
+        check_join_lines(
+            r"
+fn foo() {
+    match ty {
+        <|> Some(ty) => {
+            match ty {
+                _ => false,
+            }
+        }
+        _ => true,
+    }
+}
+",
+            r"
+fn foo() {
+    match ty {
+        <|> Some(ty) => match ty {
+                _ => false,
+            },
+        _ => true,
+    }
+}
+",
+        );
+    }
+
+    #[test]
+    fn join_lines_keeps_comma_for_block_in_match_arm() {
+        // We already have a comma
+        check_join_lines(
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>{
+            u.foo()
+        },
+        Err(v) => v,
+    }
+}",
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>u.foo(),
+        Err(v) => v,
+    }
+}",
+        );
+
+        // comma with whitespace between brace and ,
+        check_join_lines(
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>{
+            u.foo()
+        }    ,
+        Err(v) => v,
+    }
+}",
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>u.foo()    ,
+        Err(v) => v,
+    }
+}",
+        );
+
+        // comma with newline between brace and ,
+        check_join_lines(
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>{
+            u.foo()
+        }
+        ,
+        Err(v) => v,
+    }
+}",
+            r"
+fn foo(e: Result<U, V>) {
+    match e {
+        Ok(u) => <|>u.foo()
+        ,
+        Err(v) => v,
+    }
+}",
+        );
+    }
+
+    #[test]
+    fn join_lines_keeps_comma_with_single_arg_tuple() {
+        // A single arg tuple
+        check_join_lines(
+            r"
+fn foo() {
+    let x = (<|>{
+       4
+    },);
+}",
+            r"
+fn foo() {
+    let x = (<|>4,);
+}",
+        );
+
+        // single arg tuple with whitespace between brace and comma
+        check_join_lines(
+            r"
+fn foo() {
+    let x = (<|>{
+       4
+    }   ,);
+}",
+            r"
+fn foo() {
+    let x = (<|>4   ,);
+}",
+        );
+
+        // single arg tuple with newline between brace and comma
+        check_join_lines(
+            r"
+fn foo() {
+    let x = (<|>{
+       4
+    }
+    ,);
+}",
+            r"
+fn foo() {
+    let x = (<|>4
+    ,);
+}",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_items_left() {
+        // No space after the '{'
+        check_join_lines(
+            r"
+<|>use syntax::{
+    TextSize, TextRange,
+};",
+            r"
+<|>use syntax::{TextSize, TextRange,
+};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_items_right() {
+        // No space after the '}'
+        check_join_lines(
+            r"
+use syntax::{
+<|>    TextSize, TextRange
+};",
+            r"
+use syntax::{
+<|>    TextSize, TextRange};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_items_right_comma() {
+        // No space after the '}'
+        check_join_lines(
+            r"
+use syntax::{
+<|>    TextSize, TextRange,
+};",
+            r"
+use syntax::{
+<|>    TextSize, TextRange};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_use_tree() {
+        check_join_lines(
+            r"
+use syntax::{
+    algo::<|>{
+        find_token_at_offset,
+    },
+    ast,
+};",
+            r"
+use syntax::{
+    algo::<|>find_token_at_offset,
+    ast,
+};",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_normal_comments() {
+        check_join_lines(
+            r"
+fn foo() {
+    // Hello<|>
+    // world!
+}
+",
+            r"
+fn foo() {
+    // Hello<|> world!
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_doc_comments() {
+        check_join_lines(
+            r"
+fn foo() {
+    /// Hello<|>
+    /// world!
+}
+",
+            r"
+fn foo() {
+    /// Hello<|> world!
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_mod_comments() {
+        check_join_lines(
+            r"
+fn foo() {
+    //! Hello<|>
+    //! world!
+}
+",
+            r"
+fn foo() {
+    //! Hello<|> world!
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_multiline_comments_1() {
+        check_join_lines(
+            r"
+fn foo() {
+    // Hello<|>
+    /* world! */
+}
+",
+            r"
+fn foo() {
+    // Hello<|> world! */
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_multiline_comments_2() {
+        check_join_lines(
+            r"
+fn foo() {
+    // The<|>
+    /* quick
+    brown
+    fox! */
+}
+",
+            r"
+fn foo() {
+    // The<|> quick
+    brown
+    fox! */
+}
+",
+        );
+    }
+
+    fn check_join_lines_sel(before: &str, after: &str) {
+        let (sel, before) = extract_range(before);
+        let parse = SourceFile::parse(&before);
+        let result = join_lines(&parse.tree(), sel);
+        let actual = {
+            let mut actual = before.to_string();
+            result.apply(&mut actual);
+            actual
+        };
+        assert_eq_text!(after, &actual);
+    }
+
+    #[test]
+    fn test_join_lines_selection_fn_args() {
+        check_join_lines_sel(
+            r"
+fn foo() {
+    <|>foo(1,
+        2,
+        3,
+    <|>)
+}
+    ",
+            r"
+fn foo() {
+    foo(1, 2, 3)
+}
+    ",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_selection_struct() {
+        check_join_lines_sel(
+            r"
+struct Foo <|>{
+    f: u32,
+}<|>
+    ",
+            r"
+struct Foo { f: u32 }
+    ",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_selection_dot_chain() {
+        check_join_lines_sel(
+            r"
+fn foo() {
+    join(<|>type_params.type_params()
+            .filter_map(|it| it.name())
+            .map(|it| it.text())<|>)
+}",
+            r"
+fn foo() {
+    join(type_params.type_params().filter_map(|it| it.name()).map(|it| it.text()))
+}",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_selection_lambda_block_body() {
+        check_join_lines_sel(
+            r"
+pub fn handle_find_matching_brace() {
+    params.offsets
+        .map(|offset| <|>{
+            world.analysis().matching_brace(&file, offset).unwrap_or(offset)
+        }<|>)
+        .collect();
+}",
+            r"
+pub fn handle_find_matching_brace() {
+    params.offsets
+        .map(|offset| world.analysis().matching_brace(&file, offset).unwrap_or(offset))
+        .collect();
+}",
+        );
+    }
+
+    #[test]
+    fn test_join_lines_commented_block() {
+        check_join_lines(
+            r"
+fn main() {
+    let _ = {
+        // <|>foo
+        // bar
+        92
+    };
+}
+        ",
+            r"
+fn main() {
+    let _ = {
+        // <|>foo bar
+        92
+    };
+}
+        ",
+        )
+    }
+
+    #[test]
+    fn join_lines_mandatory_blocks_block() {
+        check_join_lines(
+            r"
+<|>fn foo() {
+    92
+}
+        ",
+            r"
+<|>fn foo() { 92
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>if true {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>if true { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>loop {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>loop { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>unsafe {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>unsafe { 92
+    }
+}
+        ",
+        );
+    }
+}
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
new file mode 100644
index 000000000..570790384
--- /dev/null
+++ b/crates/ide/src/lib.rs
@@ -0,0 +1,516 @@
+//! ide crate provides "ide-centric" APIs for the rust-analyzer. That is,
+//! it generally operates with files and text ranges, and returns results as
+//! Strings, suitable for displaying to the human.
+//!
+//! What powers this API are the `RootDatabase` struct, which defines a `salsa`
+//! database, and the `hir` crate, where majority of the analysis happens.
+//! However, IDE specific bits of the analysis (most notably completion) happen
+//! in this crate.
+
+// For proving that RootDatabase is RefUnwindSafe.
+#![recursion_limit = "128"]
+
+#[allow(unused)]
+macro_rules! eprintln {
+    ($($tt:tt)*) => { stdx::eprintln!($($tt)*) };
+}
+
+pub mod mock_analysis;
+
+mod markup;
+mod prime_caches;
+mod display;
+
+mod call_hierarchy;
+mod call_info;
+mod completion;
+mod diagnostics;
+mod expand_macro;
+mod extend_selection;
+mod file_structure;
+mod folding_ranges;
+mod goto_definition;
+mod goto_implementation;
+mod goto_type_definition;
+mod hover;
+mod inlay_hints;
+mod join_lines;
+mod matching_brace;
+mod parent_module;
+mod references;
+mod runnables;
+mod status;
+mod syntax_highlighting;
+mod syntax_tree;
+mod typing;
+mod link_rewrite;
+
+use std::sync::Arc;
+
+use base_db::{
+    salsa::{self, ParallelDatabase},
+    CheckCanceled, Env, FileLoader, FileSet, SourceDatabase, VfsPath,
+};
+use cfg::CfgOptions;
+use ide_db::{
+    symbol_index::{self, FileSymbol},
+    LineIndexDatabase,
+};
+use syntax::{SourceFile, TextRange, TextSize};
+
+use crate::display::ToNav;
+
+pub use crate::{
+    call_hierarchy::CallItem,
+    call_info::CallInfo,
+    completion::{
+        CompletionConfig, CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat,
+    },
+    diagnostics::{Diagnostic, DiagnosticsConfig, Fix, Severity},
+    display::NavigationTarget,
+    expand_macro::ExpandedMacro,
+    file_structure::StructureNode,
+    folding_ranges::{Fold, FoldKind},
+    hover::{HoverAction, HoverConfig, HoverGotoTypeData, HoverResult},
+    inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
+    markup::Markup,
+    references::{Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult},
+    runnables::{Runnable, RunnableKind, TestId},
+    syntax_highlighting::{
+        Highlight, HighlightModifier, HighlightModifiers, HighlightTag, HighlightedRange,
+    },
+};
+
+pub use assists::{Assist, AssistConfig, AssistId, AssistKind, ResolvedAssist};
+pub use base_db::{
+    Canceled, CrateGraph, CrateId, Edition, FileId, FilePosition, FileRange, SourceRoot,
+    SourceRootId,
+};
+pub use hir::{Documentation, Semantics};
+pub use ide_db::{
+    change::AnalysisChange,
+    label::Label,
+    line_index::{LineCol, LineIndex},
+    search::SearchScope,
+    source_change::{FileSystemEdit, SourceChange, SourceFileEdit},
+    symbol_index::Query,
+    RootDatabase,
+};
+pub use ssr::SsrError;
+pub use text_edit::{Indel, TextEdit};
+
+pub type Cancelable<T> = Result<T, Canceled>;
+
+/// Info associated with a text range.
+#[derive(Debug)]
+pub struct RangeInfo<T> {
+    pub range: TextRange,
+    pub info: T,
+}
+
+impl<T> RangeInfo<T> {
+    pub fn new(range: TextRange, info: T) -> RangeInfo<T> {
+        RangeInfo { range, info }
+    }
+}
+
+/// `AnalysisHost` stores the current state of the world.
+#[derive(Debug)]
+pub struct AnalysisHost {
+    db: RootDatabase,
+}
+
+impl AnalysisHost {
+    pub fn new(lru_capacity: Option<usize>) -> AnalysisHost {
+        AnalysisHost { db: RootDatabase::new(lru_capacity) }
+    }
+
+    pub fn update_lru_capacity(&mut self, lru_capacity: Option<usize>) {
+        self.db.update_lru_capacity(lru_capacity);
+    }
+
+    /// Returns a snapshot of the current state, which you can query for
+    /// semantic information.
+    pub fn analysis(&self) -> Analysis {
+        Analysis { db: self.db.snapshot() }
+    }
+
+    /// Applies changes to the current state of the world. If there are
+    /// outstanding snapshots, they will be canceled.
+    pub fn apply_change(&mut self, change: AnalysisChange) {
+        self.db.apply_change(change)
+    }
+
+    pub fn maybe_collect_garbage(&mut self) {
+        self.db.maybe_collect_garbage();
+    }
+
+    pub fn collect_garbage(&mut self) {
+        self.db.collect_garbage();
+    }
+    /// NB: this clears the database
+    pub fn per_query_memory_usage(&mut self) -> Vec<(String, profile::Bytes)> {
+        self.db.per_query_memory_usage()
+    }
+    pub fn request_cancellation(&mut self) {
+        self.db.request_cancellation();
+    }
+    pub fn raw_database(&self) -> &RootDatabase {
+        &self.db
+    }
+    pub fn raw_database_mut(&mut self) -> &mut RootDatabase {
+        &mut self.db
+    }
+}
+
+impl Default for AnalysisHost {
+    fn default() -> AnalysisHost {
+        AnalysisHost::new(None)
+    }
+}
+
+/// Analysis is a snapshot of a world state at a moment in time. It is the main
+/// entry point for asking semantic information about the world. When the world
+/// state is advanced using `AnalysisHost::apply_change` method, all existing
+/// `Analysis` are canceled (most method return `Err(Canceled)`).
+#[derive(Debug)]
+pub struct Analysis {
+    db: salsa::Snapshot<RootDatabase>,
+}
+
+// As a general design guideline, `Analysis` API are intended to be independent
+// from the language server protocol. That is, when exposing some functionality
+// we should think in terms of "what API makes most sense" and not in terms of
+// "what types LSP uses". Although currently LSP is the only consumer of the
+// API, the API should in theory be usable as a library, or via a different
+// protocol.
+impl Analysis {
+    // Creates an analysis instance for a single file, without any extenal
+    // dependencies, stdlib support or ability to apply changes. See
+    // `AnalysisHost` for creating a fully-featured analysis.
+    pub fn from_single_file(text: String) -> (Analysis, FileId) {
+        let mut host = AnalysisHost::default();
+        let file_id = FileId(0);
+        let mut file_set = FileSet::default();
+        file_set.insert(file_id, VfsPath::new_virtual_path("/main.rs".to_string()));
+        let source_root = SourceRoot::new_local(file_set);
+
+        let mut change = AnalysisChange::new();
+        change.set_roots(vec![source_root]);
+        let mut crate_graph = CrateGraph::default();
+        // FIXME: cfg options
+        // Default to enable test for single file.
+        let mut cfg_options = CfgOptions::default();
+        cfg_options.insert_atom("test".into());
+        crate_graph.add_crate_root(
+            file_id,
+            Edition::Edition2018,
+            None,
+            cfg_options,
+            Env::default(),
+            Default::default(),
+        );
+        change.change_file(file_id, Some(Arc::new(text)));
+        change.set_crate_graph(crate_graph);
+        host.apply_change(change);
+        (host.analysis(), file_id)
+    }
+
+    /// Debug info about the current state of the analysis.
+    pub fn status(&self) -> Cancelable<String> {
+        self.with_db(|db| status::status(&*db))
+    }
+
+    pub fn prime_caches(&self, files: Vec<FileId>) -> Cancelable<()> {
+        self.with_db(|db| prime_caches::prime_caches(db, files))
+    }
+
+    /// Gets the text of the source file.
+    pub fn file_text(&self, file_id: FileId) -> Cancelable<Arc<String>> {
+        self.with_db(|db| db.file_text(file_id))
+    }
+
+    /// Gets the syntax tree of the file.
+    pub fn parse(&self, file_id: FileId) -> Cancelable<SourceFile> {
+        self.with_db(|db| db.parse(file_id).tree())
+    }
+
+    /// Gets the file's `LineIndex`: data structure to convert between absolute
+    /// offsets and line/column representation.
+    pub fn file_line_index(&self, file_id: FileId) -> Cancelable<Arc<LineIndex>> {
+        self.with_db(|db| db.line_index(file_id))
+    }
+
+    /// Selects the next syntactic nodes encompassing the range.
+    pub fn extend_selection(&self, frange: FileRange) -> Cancelable<TextRange> {
+        self.with_db(|db| extend_selection::extend_selection(db, frange))
+    }
+
+    /// Returns position of the matching brace (all types of braces are
+    /// supported).
+    pub fn matching_brace(&self, position: FilePosition) -> Cancelable<Option<TextSize>> {
+        self.with_db(|db| {
+            let parse = db.parse(position.file_id);
+            let file = parse.tree();
+            matching_brace::matching_brace(&file, position.offset)
+        })
+    }
+
+    /// Returns a syntax tree represented as `String`, for debug purposes.
+    // FIXME: use a better name here.
+    pub fn syntax_tree(
+        &self,
+        file_id: FileId,
+        text_range: Option<TextRange>,
+    ) -> Cancelable<String> {
+        self.with_db(|db| syntax_tree::syntax_tree(&db, file_id, text_range))
+    }
+
+    pub fn expand_macro(&self, position: FilePosition) -> Cancelable<Option<ExpandedMacro>> {
+        self.with_db(|db| expand_macro::expand_macro(db, position))
+    }
+
+    /// Returns an edit to remove all newlines in the range, cleaning up minor
+    /// stuff like trailing commas.
+    pub fn join_lines(&self, frange: FileRange) -> Cancelable<TextEdit> {
+        self.with_db(|db| {
+            let parse = db.parse(frange.file_id);
+            join_lines::join_lines(&parse.tree(), frange.range)
+        })
+    }
+
+    /// Returns an edit which should be applied when opening a new line, fixing
+    /// up minor stuff like continuing the comment.
+    /// The edit will be a snippet (with `$0`).
+    pub fn on_enter(&self, position: FilePosition) -> Cancelable<Option<TextEdit>> {
+        self.with_db(|db| typing::on_enter(&db, position))
+    }
+
+    /// Returns an edit which should be applied after a character was typed.
+    ///
+    /// This is useful for some on-the-fly fixups, like adding `;` to `let =`
+    /// automatically.
+    pub fn on_char_typed(
+        &self,
+        position: FilePosition,
+        char_typed: char,
+    ) -> Cancelable<Option<SourceChange>> {
+        // Fast path to not even parse the file.
+        if !typing::TRIGGER_CHARS.contains(char_typed) {
+            return Ok(None);
+        }
+        self.with_db(|db| typing::on_char_typed(&db, position, char_typed))
+    }
+
+    /// Returns a tree representation of symbols in the file. Useful to draw a
+    /// file outline.
+    pub fn file_structure(&self, file_id: FileId) -> Cancelable<Vec<StructureNode>> {
+        self.with_db(|db| file_structure::file_structure(&db.parse(file_id).tree()))
+    }
+
+    /// Returns a list of the places in the file where type hints can be displayed.
+    pub fn inlay_hints(
+        &self,
+        file_id: FileId,
+        config: &InlayHintsConfig,
+    ) -> Cancelable<Vec<InlayHint>> {
+        self.with_db(|db| inlay_hints::inlay_hints(db, file_id, config))
+    }
+
+    /// Returns the set of folding ranges.
+    pub fn folding_ranges(&self, file_id: FileId) -> Cancelable<Vec<Fold>> {
+        self.with_db(|db| folding_ranges::folding_ranges(&db.parse(file_id).tree()))
+    }
+
+    /// Fuzzy searches for a symbol.
+    pub fn symbol_search(&self, query: Query) -> Cancelable<Vec<NavigationTarget>> {
+        self.with_db(|db| {
+            symbol_index::world_symbols(db, query)
+                .into_iter()
+                .map(|s| s.to_nav(db))
+                .collect::<Vec<_>>()
+        })
+    }
+
+    /// Returns the definitions from the symbol at `position`.
+    pub fn goto_definition(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
+        self.with_db(|db| goto_definition::goto_definition(db, position))
+    }
+
+    /// Returns the impls from the symbol at `position`.
+    pub fn goto_implementation(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
+        self.with_db(|db| goto_implementation::goto_implementation(db, position))
+    }
+
+    /// Returns the type definitions for the symbol at `position`.
+    pub fn goto_type_definition(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
+        self.with_db(|db| goto_type_definition::goto_type_definition(db, position))
+    }
+
+    /// Finds all usages of the reference at point.
+    pub fn find_all_refs(
+        &self,
+        position: FilePosition,
+        search_scope: Option<SearchScope>,
+    ) -> Cancelable<Option<ReferenceSearchResult>> {
+        self.with_db(|db| {
+            references::find_all_refs(&Semantics::new(db), position, search_scope).map(|it| it.info)
+        })
+    }
+
+    /// Returns a short text describing element at position.
+    pub fn hover(&self, position: FilePosition) -> Cancelable<Option<RangeInfo<HoverResult>>> {
+        self.with_db(|db| hover::hover(db, position))
+    }
+
+    /// Computes parameter information for the given call expression.
+    pub fn call_info(&self, position: FilePosition) -> Cancelable<Option<CallInfo>> {
+        self.with_db(|db| call_info::call_info(db, position))
+    }
+
+    /// Computes call hierarchy candidates for the given file position.
+    pub fn call_hierarchy(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
+        self.with_db(|db| call_hierarchy::call_hierarchy(db, position))
+    }
+
+    /// Computes incoming calls for the given file position.
+    pub fn incoming_calls(&self, position: FilePosition) -> Cancelable<Option<Vec<CallItem>>> {
+        self.with_db(|db| call_hierarchy::incoming_calls(db, position))
+    }
+
+    /// Computes incoming calls for the given file position.
+    pub fn outgoing_calls(&self, position: FilePosition) -> Cancelable<Option<Vec<CallItem>>> {
+        self.with_db(|db| call_hierarchy::outgoing_calls(db, position))
+    }
+
+    /// Returns a `mod name;` declaration which created the current module.
+    pub fn parent_module(&self, position: FilePosition) -> Cancelable<Vec<NavigationTarget>> {
+        self.with_db(|db| parent_module::parent_module(db, position))
+    }
+
+    /// Returns crates this file belongs too.
+    pub fn crate_for(&self, file_id: FileId) -> Cancelable<Vec<CrateId>> {
+        self.with_db(|db| parent_module::crate_for(db, file_id))
+    }
+
+    /// Returns the edition of the given crate.
+    pub fn crate_edition(&self, crate_id: CrateId) -> Cancelable<Edition> {
+        self.with_db(|db| db.crate_graph()[crate_id].edition)
+    }
+
+    /// Returns the root file of the given crate.
+    pub fn crate_root(&self, crate_id: CrateId) -> Cancelable<FileId> {
+        self.with_db(|db| db.crate_graph()[crate_id].root_file_id)
+    }
+
+    /// Returns the set of possible targets to run for the current file.
+    pub fn runnables(&self, file_id: FileId) -> Cancelable<Vec<Runnable>> {
+        self.with_db(|db| runnables::runnables(db, file_id))
+    }
+
+    /// Computes syntax highlighting for the given file
+    pub fn highlight(&self, file_id: FileId) -> Cancelable<Vec<HighlightedRange>> {
+        self.with_db(|db| syntax_highlighting::highlight(db, file_id, None, false))
+    }
+
+    /// Computes syntax highlighting for the given file range.
+    pub fn highlight_range(&self, frange: FileRange) -> Cancelable<Vec<HighlightedRange>> {
+        self.with_db(|db| {
+            syntax_highlighting::highlight(db, frange.file_id, Some(frange.range), false)
+        })
+    }
+
+    /// Computes syntax highlighting for the given file.
+    pub fn highlight_as_html(&self, file_id: FileId, rainbow: bool) -> Cancelable<String> {
+        self.with_db(|db| syntax_highlighting::highlight_as_html(db, file_id, rainbow))
+    }
+
+    /// Computes completions at the given position.
+    pub fn completions(
+        &self,
+        config: &CompletionConfig,
+        position: FilePosition,
+    ) -> Cancelable<Option<Vec<CompletionItem>>> {
+        self.with_db(|db| completion::completions(db, config, position).map(Into::into))
+    }
+
+    /// Computes resolved assists with source changes for the given position.
+    pub fn resolved_assists(
+        &self,
+        config: &AssistConfig,
+        frange: FileRange,
+    ) -> Cancelable<Vec<ResolvedAssist>> {
+        self.with_db(|db| assists::Assist::resolved(db, config, frange))
+    }
+
+    /// Computes unresolved assists (aka code actions aka intentions) for the given
+    /// position.
+    pub fn unresolved_assists(
+        &self,
+        config: &AssistConfig,
+        frange: FileRange,
+    ) -> Cancelable<Vec<Assist>> {
+        self.with_db(|db| Assist::unresolved(db, config, frange))
+    }
+
+    /// Computes the set of diagnostics for the given file.
+    pub fn diagnostics(
+        &self,
+        config: &DiagnosticsConfig,
+        file_id: FileId,
+    ) -> Cancelable<Vec<Diagnostic>> {
+        self.with_db(|db| diagnostics::diagnostics(db, config, file_id))
+    }
+
+    /// Returns the edit required to rename reference at the position to the new
+    /// name.
+    pub fn rename(
+        &self,
+        position: FilePosition,
+        new_name: &str,
+    ) -> Cancelable<Option<RangeInfo<SourceChange>>> {
+        self.with_db(|db| references::rename(db, position, new_name))
+    }
+
+    pub fn structural_search_replace(
+        &self,
+        query: &str,
+        parse_only: bool,
+        resolve_context: FilePosition,
+        selections: Vec<FileRange>,
+    ) -> Cancelable<Result<SourceChange, SsrError>> {
+        self.with_db(|db| {
+            let rule: ssr::SsrRule = query.parse()?;
+            let mut match_finder = ssr::MatchFinder::in_context(db, resolve_context, selections);
+            match_finder.add_rule(rule)?;
+            let edits = if parse_only { Vec::new() } else { match_finder.edits() };
+            Ok(SourceChange::from(edits))
+        })
+    }
+
+    /// Performs an operation on that may be Canceled.
+    fn with_db<F, T>(&self, f: F) -> Cancelable<T>
+    where
+        F: FnOnce(&RootDatabase) -> T + std::panic::UnwindSafe,
+    {
+        self.db.catch_canceled(f)
+    }
+}
+
+#[test]
+fn analysis_is_send() {
+    fn is_send<T: Send>() {}
+    is_send::<Analysis>();
+}
diff --git a/crates/ide/src/link_rewrite.rs b/crates/ide/src/link_rewrite.rs
new file mode 100644
index 000000000..a826220e3
--- /dev/null
+++ b/crates/ide/src/link_rewrite.rs
@@ -0,0 +1,79 @@
+//! This is a wrapper around [`hir::link_rewrite`] connecting it to the markdown parser.
+
+use pulldown_cmark::{CowStr, Event, Options, Parser, Tag};
+use pulldown_cmark_to_cmark::{cmark_with_options, Options as CmarkOptions};
+
+use hir::resolve_doc_link;
+use ide_db::{defs::Definition, RootDatabase};
+
+/// Rewrite documentation links in markdown to point to an online host (e.g. docs.rs)
+pub fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition) -> String {
+    let doc = Parser::new_with_broken_link_callback(
+        markdown,
+        Options::empty(),
+        Some(&|label, _| Some((/*url*/ label.to_string(), /*title*/ label.to_string()))),
+    );
+
+    let doc = map_links(doc, |target, title: &str| {
+        // This check is imperfect, there's some overlap between valid intra-doc links
+        // and valid URLs so we choose to be too eager to try to resolve what might be
+        // a URL.
+        if target.contains("://") {
+            (target.to_string(), title.to_string())
+        } else {
+            // Two posibilities:
+            // * path-based links: `../../module/struct.MyStruct.html`
+            // * module-based links (AKA intra-doc links): `super::super::module::MyStruct`
+            let resolved = match definition {
+                Definition::ModuleDef(t) => resolve_doc_link(db, t, title, target),
+                Definition::Macro(t) => resolve_doc_link(db, t, title, target),
+                Definition::Field(t) => resolve_doc_link(db, t, title, target),
+                Definition::SelfType(t) => resolve_doc_link(db, t, title, target),
+                Definition::Local(t) => resolve_doc_link(db, t, title, target),
+                Definition::TypeParam(t) => resolve_doc_link(db, t, title, target),
+            };
+
+            match resolved {
+                Some((target, title)) => (target, title),
+                None => (target.to_string(), title.to_string()),
+            }
+        }
+    });
+    let mut out = String::new();
+    let mut options = CmarkOptions::default();
+    options.code_block_backticks = 3;
+    cmark_with_options(doc, &mut out, None, options).ok();
+    out
+}
+
+// Rewrites a markdown document, resolving links using `callback` and additionally striping prefixes/suffixes on link titles.
+fn map_links<'e>(
+    events: impl Iterator<Item = Event<'e>>,
+    callback: impl Fn(&str, &str) -> (String, String),
+) -> impl Iterator<Item = Event<'e>> {
+    let mut in_link = false;
+    let mut link_target: Option<CowStr> = None;
+
+    events.map(move |evt| match evt {
+        Event::Start(Tag::Link(_link_type, ref target, _)) => {
+            in_link = true;
+            link_target = Some(target.clone());
+            evt
+        }
+        Event::End(Tag::Link(link_type, _target, _)) => {
+            in_link = false;
+            Event::End(Tag::Link(link_type, link_target.take().unwrap(), CowStr::Borrowed("")))
+        }
+        Event::Text(s) if in_link => {
+            let (link_target_s, link_name) = callback(&link_target.take().unwrap(), &s);
+            link_target = Some(CowStr::Boxed(link_target_s.into()));
+            Event::Text(CowStr::Boxed(link_name.into()))
+        }
+        Event::Code(s) if in_link => {
+            let (link_target_s, link_name) = callback(&link_target.take().unwrap(), &s);
+            link_target = Some(CowStr::Boxed(link_target_s.into()));
+            Event::Code(CowStr::Boxed(link_name.into()))
+        }
+        _ => evt,
+    })
+}
diff --git a/crates/ide/src/markup.rs b/crates/ide/src/markup.rs
new file mode 100644
index 000000000..60c193c40
--- /dev/null
+++ b/crates/ide/src/markup.rs
@@ -0,0 +1,38 @@
+//! Markdown formatting.
+//!
+//! Sometimes, we want to display a "rich text" in the UI. At the moment, we use
+//! markdown for this purpose. It doesn't feel like a right option, but that's
+//! what is used by LSP, so let's keep it simple.
+use std::fmt;
+
+#[derive(Default, Debug)]
+pub struct Markup {
+    text: String,
+}
+
+impl From<Markup> for String {
+    fn from(markup: Markup) -> Self {
+        markup.text
+    }
+}
+
+impl From<String> for Markup {
+    fn from(text: String) -> Self {
+        Markup { text }
+    }
+}
+
+impl fmt::Display for Markup {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.text, f)
+    }
+}
+
+impl Markup {
+    pub fn as_str(&self) -> &str {
+        self.text.as_str()
+    }
+    pub fn fenced_block(contents: &impl fmt::Display) -> Markup {
+        format!("```rust\n{}\n```", contents).into()
+    }
+}
diff --git a/crates/ide/src/matching_brace.rs b/crates/ide/src/matching_brace.rs
new file mode 100644
index 000000000..cb6abb0db
--- /dev/null
+++ b/crates/ide/src/matching_brace.rs
@@ -0,0 +1,73 @@
+use syntax::{
+    ast::{self, AstNode},
+    SourceFile, SyntaxKind, TextSize, T,
+};
+use test_utils::mark;
+
+// Feature: Matching Brace
+//
+// If the cursor is on any brace (`<>(){}[]||`) which is a part of a brace-pair,
+// moves cursor to the matching brace. It uses the actual parser to determine
+// braces, so it won't confuse generics with comparisons.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Find matching brace**
+// |===
+pub fn matching_brace(file: &SourceFile, offset: TextSize) -> Option<TextSize> {
+    const BRACES: &[SyntaxKind] =
+        &[T!['{'], T!['}'], T!['['], T![']'], T!['('], T![')'], T![<], T![>], T![|], T![|]];
+    let (brace_token, brace_idx) = file
+        .syntax()
+        .token_at_offset(offset)
+        .filter_map(|node| {
+            let idx = BRACES.iter().position(|&brace| brace == node.kind())?;
+            Some((node, idx))
+        })
+        .next()?;
+    let parent = brace_token.parent();
+    if brace_token.kind() == T![|] && !ast::ParamList::can_cast(parent.kind()) {
+        mark::hit!(pipes_not_braces);
+        return None;
+    }
+    let matching_kind = BRACES[brace_idx ^ 1];
+    let matching_node = parent
+        .children_with_tokens()
+        .filter_map(|it| it.into_token())
+        .find(|node| node.kind() == matching_kind && node != &brace_token)?;
+    Some(matching_node.text_range().start())
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::{add_cursor, assert_eq_text, extract_offset};
+
+    use super::*;
+
+    #[test]
+    fn test_matching_brace() {
+        fn do_check(before: &str, after: &str) {
+            let (pos, before) = extract_offset(before);
+            let parse = SourceFile::parse(&before);
+            let new_pos = match matching_brace(&parse.tree(), pos) {
+                None => pos,
+                Some(pos) => pos,
+            };
+            let actual = add_cursor(&before, new_pos);
+            assert_eq_text!(after, &actual);
+        }
+
+        do_check("struct Foo { a: i32, }<|>", "struct Foo <|>{ a: i32, }");
+        do_check("fn main() { |x: i32|<|> x * 2;}", "fn main() { <|>|x: i32| x * 2;}");
+        do_check("fn main() { <|>|x: i32| x * 2;}", "fn main() { |x: i32<|>| x * 2;}");
+
+        {
+            mark::check!(pipes_not_braces);
+            do_check(
+                "fn main() { match 92 { 1 | 2 |<|> 3 => 92 } }",
+                "fn main() { match 92 { 1 | 2 |<|> 3 => 92 } }",
+            );
+        }
+    }
+}
diff --git a/crates/ide/src/mock_analysis.rs b/crates/ide/src/mock_analysis.rs
new file mode 100644
index 000000000..235796dbc
--- /dev/null
+++ b/crates/ide/src/mock_analysis.rs
@@ -0,0 +1,176 @@
+//! FIXME: write short doc here
+use std::sync::Arc;
+
+use base_db::{CrateName, FileSet, SourceRoot, VfsPath};
+use cfg::CfgOptions;
+use test_utils::{
+    extract_annotations, extract_range_or_offset, Fixture, RangeOrOffset, CURSOR_MARKER,
+};
+
+use crate::{
+    Analysis, AnalysisChange, AnalysisHost, CrateGraph, Edition, FileId, FilePosition, FileRange,
+};
+
+/// Mock analysis is used in test to bootstrap an AnalysisHost/Analysis
+/// from a set of in-memory files.
+#[derive(Debug, Default)]
+pub struct MockAnalysis {
+    files: Vec<Fixture>,
+}
+
+impl MockAnalysis {
+    /// Creates `MockAnalysis` using a fixture data in the following format:
+    ///
+    /// ```not_rust
+    /// //- /main.rs
+    /// mod foo;
+    /// fn main() {}
+    ///
+    /// //- /foo.rs
+    /// struct Baz;
+    /// ```
+    pub fn with_files(ra_fixture: &str) -> MockAnalysis {
+        let (res, pos) = MockAnalysis::with_fixture(ra_fixture);
+        assert!(pos.is_none());
+        res
+    }
+
+    /// Same as `with_files`, but requires that a single file contains a `<|>` marker,
+    /// whose position is also returned.
+    pub fn with_files_and_position(fixture: &str) -> (MockAnalysis, FilePosition) {
+        let (res, position) = MockAnalysis::with_fixture(fixture);
+        let (file_id, range_or_offset) = position.expect("expected a marker (<|>)");
+        let offset = match range_or_offset {
+            RangeOrOffset::Range(_) => panic!(),
+            RangeOrOffset::Offset(it) => it,
+        };
+        (res, FilePosition { file_id, offset })
+    }
+
+    fn with_fixture(fixture: &str) -> (MockAnalysis, Option<(FileId, RangeOrOffset)>) {
+        let mut position = None;
+        let mut res = MockAnalysis::default();
+        for mut entry in Fixture::parse(fixture) {
+            if entry.text.contains(CURSOR_MARKER) {
+                assert!(position.is_none(), "only one marker (<|>) per fixture is allowed");
+                let (range_or_offset, text) = extract_range_or_offset(&entry.text);
+                entry.text = text;
+                let file_id = res.add_file_fixture(entry);
+                position = Some((file_id, range_or_offset));
+            } else {
+                res.add_file_fixture(entry);
+            }
+        }
+        (res, position)
+    }
+
+    fn add_file_fixture(&mut self, fixture: Fixture) -> FileId {
+        let file_id = FileId((self.files.len() + 1) as u32);
+        self.files.push(fixture);
+        file_id
+    }
+
+    pub fn id_of(&self, path: &str) -> FileId {
+        let (file_id, _) =
+            self.files().find(|(_, data)| path == data.path).expect("no file in this mock");
+        file_id
+    }
+    pub fn annotations(&self) -> Vec<(FileRange, String)> {
+        self.files()
+            .flat_map(|(file_id, fixture)| {
+                let annotations = extract_annotations(&fixture.text);
+                annotations
+                    .into_iter()
+                    .map(move |(range, data)| (FileRange { file_id, range }, data))
+            })
+            .collect()
+    }
+    pub fn files(&self) -> impl Iterator<Item = (FileId, &Fixture)> + '_ {
+        self.files.iter().enumerate().map(|(idx, fixture)| (FileId(idx as u32 + 1), fixture))
+    }
+    pub fn annotation(&self) -> (FileRange, String) {
+        let mut all = self.annotations();
+        assert_eq!(all.len(), 1);
+        all.pop().unwrap()
+    }
+    pub fn analysis_host(self) -> AnalysisHost {
+        let mut host = AnalysisHost::default();
+        let mut change = AnalysisChange::new();
+        let mut file_set = FileSet::default();
+        let mut crate_graph = CrateGraph::default();
+        let mut root_crate = None;
+        for (i, data) in self.files.into_iter().enumerate() {
+            let path = data.path;
+            assert!(path.starts_with('/'));
+
+            let mut cfg = CfgOptions::default();
+            data.cfg_atoms.iter().for_each(|it| cfg.insert_atom(it.into()));
+            data.cfg_key_values.iter().for_each(|(k, v)| cfg.insert_key_value(k.into(), v.into()));
+            let edition: Edition =
+                data.edition.and_then(|it| it.parse().ok()).unwrap_or(Edition::Edition2018);
+
+            let file_id = FileId(i as u32 + 1);
+            let env = data.env.into_iter().collect();
+            if path == "/lib.rs" || path == "/main.rs" {
+                root_crate = Some(crate_graph.add_crate_root(
+                    file_id,
+                    edition,
+                    Some("test".to_string()),
+                    cfg,
+                    env,
+                    Default::default(),
+                ));
+            } else if path.ends_with("/lib.rs") {
+                let base = &path[..path.len() - "/lib.rs".len()];
+                let crate_name = &base[base.rfind('/').unwrap() + '/'.len_utf8()..];
+                let other_crate = crate_graph.add_crate_root(
+                    file_id,
+                    edition,
+                    Some(crate_name.to_string()),
+                    cfg,
+                    env,
+                    Default::default(),
+                );
+                if let Some(root_crate) = root_crate {
+                    crate_graph
+                        .add_dep(root_crate, CrateName::new(crate_name).unwrap(), other_crate)
+                        .unwrap();
+                }
+            }
+            let path = VfsPath::new_virtual_path(path.to_string());
+            file_set.insert(file_id, path);
+            change.change_file(file_id, Some(Arc::new(data.text).to_owned()));
+        }
+        change.set_crate_graph(crate_graph);
+        change.set_roots(vec![SourceRoot::new_local(file_set)]);
+        host.apply_change(change);
+        host
+    }
+    pub fn analysis(self) -> Analysis {
+        self.analysis_host().analysis()
+    }
+}
+
+/// Creates analysis from a multi-file fixture, returns positions marked with <|>.
+pub fn analysis_and_position(ra_fixture: &str) -> (Analysis, FilePosition) {
+    let (mock, position) = MockAnalysis::with_files_and_position(ra_fixture);
+    (mock.analysis(), position)
+}
+
+/// Creates analysis for a single file.
+pub fn single_file(ra_fixture: &str) -> (Analysis, FileId) {
+    let mock = MockAnalysis::with_files(ra_fixture);
+    let file_id = mock.id_of("/main.rs");
+    (mock.analysis(), file_id)
+}
+
+/// Creates analysis for a single file, returns range marked with a pair of <|>.
+pub fn analysis_and_range(ra_fixture: &str) -> (Analysis, FileRange) {
+    let (res, position) = MockAnalysis::with_fixture(ra_fixture);
+    let (file_id, range_or_offset) = position.expect("expected a marker (<|>)");
+    let range = match range_or_offset {
+        RangeOrOffset::Range(it) => it,
+        RangeOrOffset::Offset(_) => panic!(),
+    };
+    (res.analysis(), FileRange { file_id, range })
+}
diff --git a/crates/ide/src/parent_module.rs b/crates/ide/src/parent_module.rs
new file mode 100644
index 000000000..59ed2967c
--- /dev/null
+++ b/crates/ide/src/parent_module.rs
@@ -0,0 +1,155 @@
+use base_db::{CrateId, FileId, FilePosition};
+use hir::Semantics;
+use ide_db::RootDatabase;
+use syntax::{
+    algo::find_node_at_offset,
+    ast::{self, AstNode},
+};
+use test_utils::mark;
+
+use crate::NavigationTarget;
+
+// Feature: Parent Module
+//
+// Navigates to the parent module of the current module.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Locate parent module**
+// |===
+
+/// This returns `Vec` because a module may be included from several places. We
+/// don't handle this case yet though, so the Vec has length at most one.
+pub(crate) fn parent_module(db: &RootDatabase, position: FilePosition) -> Vec<NavigationTarget> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(position.file_id);
+
+    let mut module = find_node_at_offset::<ast::Module>(source_file.syntax(), position.offset);
+
+    // If cursor is literally on `mod foo`, go to the grandpa.
+    if let Some(m) = &module {
+        if !m
+            .item_list()
+            .map_or(false, |it| it.syntax().text_range().contains_inclusive(position.offset))
+        {
+            mark::hit!(test_resolve_parent_module_on_module_decl);
+            module = m.syntax().ancestors().skip(1).find_map(ast::Module::cast);
+        }
+    }
+
+    let module = match module {
+        Some(module) => sema.to_def(&module),
+        None => sema.to_module_def(position.file_id),
+    };
+    let module = match module {
+        None => return Vec::new(),
+        Some(it) => it,
+    };
+    let nav = NavigationTarget::from_module_to_decl(db, module);
+    vec![nav]
+}
+
+/// Returns `Vec` for the same reason as `parent_module`
+pub(crate) fn crate_for(db: &RootDatabase, file_id: FileId) -> Vec<CrateId> {
+    let sema = Semantics::new(db);
+    let module = match sema.to_module_def(file_id) {
+        Some(it) => it,
+        None => return Vec::new(),
+    };
+    let krate = module.krate();
+    vec![krate.into()]
+}
+
+#[cfg(test)]
+mod tests {
+    use base_db::Env;
+    use cfg::CfgOptions;
+    use test_utils::mark;
+
+    use crate::{
+        mock_analysis::{analysis_and_position, MockAnalysis},
+        AnalysisChange, CrateGraph,
+        Edition::Edition2018,
+    };
+
+    #[test]
+    fn test_resolve_parent_module() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod foo;
+            //- /foo.rs
+            <|>// empty
+            ",
+        );
+        let nav = analysis.parent_module(pos).unwrap().pop().unwrap();
+        nav.assert_match("foo MODULE FileId(1) 0..8");
+    }
+
+    #[test]
+    fn test_resolve_parent_module_on_module_decl() {
+        mark::check!(test_resolve_parent_module_on_module_decl);
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod foo;
+
+            //- /foo.rs
+            mod <|>bar;
+
+            //- /foo/bar.rs
+            // empty
+            ",
+        );
+        let nav = analysis.parent_module(pos).unwrap().pop().unwrap();
+        nav.assert_match("foo MODULE FileId(1) 0..8");
+    }
+
+    #[test]
+    fn test_resolve_parent_module_for_inline() {
+        let (analysis, pos) = analysis_and_position(
+            "
+            //- /lib.rs
+            mod foo {
+                mod bar {
+                    mod baz { <|> }
+                }
+            }
+            ",
+        );
+        let nav = analysis.parent_module(pos).unwrap().pop().unwrap();
+        nav.assert_match("baz MODULE FileId(1) 32..44");
+    }
+
+    #[test]
+    fn test_resolve_crate_root() {
+        let mock = MockAnalysis::with_files(
+            r#"
+//- /bar.rs
+mod foo;
+//- /foo.rs
+// empty
+"#,
+        );
+        let root_file = mock.id_of("/bar.rs");
+        let mod_file = mock.id_of("/foo.rs");
+        let mut host = mock.analysis_host();
+        assert!(host.analysis().crate_for(mod_file).unwrap().is_empty());
+
+        let mut crate_graph = CrateGraph::default();
+        let crate_id = crate_graph.add_crate_root(
+            root_file,
+            Edition2018,
+            None,
+            CfgOptions::default(),
+            Env::default(),
+            Default::default(),
+        );
+        let mut change = AnalysisChange::new();
+        change.set_crate_graph(crate_graph);
+        host.apply_change(change);
+
+        assert_eq!(host.analysis().crate_for(mod_file).unwrap(), vec![crate_id]);
+    }
+}
diff --git a/crates/ide/src/prime_caches.rs b/crates/ide/src/prime_caches.rs
new file mode 100644
index 000000000..c5ab5a1d8
--- /dev/null
+++ b/crates/ide/src/prime_caches.rs
@@ -0,0 +1,12 @@
+//! rust-analyzer is lazy and doesn't not compute anything unless asked. This
+//! sometimes is counter productive when, for example, the first goto definition
+//! request takes longer to compute. This modules implemented prepopulating of
+//! various caches, it's not really advanced at the moment.
+
+use crate::{FileId, RootDatabase};
+
+pub(crate) fn prime_caches(db: &RootDatabase, files: Vec<FileId>) {
+    for file in files {
+        let _ = crate::syntax_highlighting::highlight(db, file, None, false);
+    }
+}
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
new file mode 100644
index 000000000..722c8f406
--- /dev/null
+++ b/crates/ide/src/references.rs
@@ -0,0 +1,696 @@
+//! This module implements a reference search.
+//! First, the element at the cursor position must be either an `ast::Name`
+//! or `ast::NameRef`. If it's a `ast::NameRef`, at the classification step we
+//! try to resolve the direct tree parent of this element, otherwise we
+//! already have a definition and just need to get its HIR together with
+//! some information that is needed for futher steps of searching.
+//! After that, we collect files that might contain references and look
+//! for text occurrences of the identifier. If there's an `ast::NameRef`
+//! at the index that the match starts at and its tree parent is
+//! resolved to the search element definition, we get a reference.
+
+mod rename;
+
+use hir::Semantics;
+use ide_db::{
+    defs::{classify_name, classify_name_ref, Definition},
+    search::SearchScope,
+    RootDatabase,
+};
+use syntax::{
+    algo::find_node_at_offset,
+    ast::{self, NameOwner},
+    AstNode, SyntaxKind, SyntaxNode, TextRange, TokenAtOffset,
+};
+
+use crate::{display::TryToNav, FilePosition, FileRange, NavigationTarget, RangeInfo};
+
+pub(crate) use self::rename::rename;
+
+pub use ide_db::search::{Reference, ReferenceAccess, ReferenceKind};
+
+#[derive(Debug, Clone)]
+pub struct ReferenceSearchResult {
+    declaration: Declaration,
+    references: Vec<Reference>,
+}
+
+#[derive(Debug, Clone)]
+pub struct Declaration {
+    pub nav: NavigationTarget,
+    pub kind: ReferenceKind,
+    pub access: Option<ReferenceAccess>,
+}
+
+impl ReferenceSearchResult {
+    pub fn declaration(&self) -> &Declaration {
+        &self.declaration
+    }
+
+    pub fn decl_target(&self) -> &NavigationTarget {
+        &self.declaration.nav
+    }
+
+    pub fn references(&self) -> &[Reference] {
+        &self.references
+    }
+
+    /// Total number of references
+    /// At least 1 since all valid references should
+    /// Have a declaration
+    pub fn len(&self) -> usize {
+        self.references.len() + 1
+    }
+}
+
+// allow turning ReferenceSearchResult into an iterator
+// over References
+impl IntoIterator for ReferenceSearchResult {
+    type Item = Reference;
+    type IntoIter = std::vec::IntoIter<Reference>;
+
+    fn into_iter(mut self) -> Self::IntoIter {
+        let mut v = Vec::with_capacity(self.len());
+        v.push(Reference {
+            file_range: FileRange {
+                file_id: self.declaration.nav.file_id,
+                range: self.declaration.nav.focus_or_full_range(),
+            },
+            kind: self.declaration.kind,
+            access: self.declaration.access,
+        });
+        v.append(&mut self.references);
+        v.into_iter()
+    }
+}
+
+pub(crate) fn find_all_refs(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    search_scope: Option<SearchScope>,
+) -> Option<RangeInfo<ReferenceSearchResult>> {
+    let _p = profile::span("find_all_refs");
+    let syntax = sema.parse(position.file_id).syntax().clone();
+
+    let (opt_name, search_kind) = if let Some(name) =
+        get_struct_def_name_for_struct_literal_search(&sema, &syntax, position)
+    {
+        (Some(name), ReferenceKind::StructLiteral)
+    } else {
+        (
+            sema.find_node_at_offset_with_descend::<ast::Name>(&syntax, position.offset),
+            ReferenceKind::Other,
+        )
+    };
+
+    let RangeInfo { range, info: def } = find_name(&sema, &syntax, position, opt_name)?;
+
+    let references = def
+        .usages(sema)
+        .set_scope(search_scope)
+        .all()
+        .into_iter()
+        .filter(|r| search_kind == ReferenceKind::Other || search_kind == r.kind)
+        .collect();
+
+    let decl_range = def.try_to_nav(sema.db)?.focus_or_full_range();
+
+    let declaration = Declaration {
+        nav: def.try_to_nav(sema.db)?,
+        kind: ReferenceKind::Other,
+        access: decl_access(&def, &syntax, decl_range),
+    };
+
+    Some(RangeInfo::new(range, ReferenceSearchResult { declaration, references }))
+}
+
+fn find_name(
+    sema: &Semantics<RootDatabase>,
+    syntax: &SyntaxNode,
+    position: FilePosition,
+    opt_name: Option<ast::Name>,
+) -> Option<RangeInfo<Definition>> {
+    if let Some(name) = opt_name {
+        let def = classify_name(sema, &name)?.definition(sema.db);
+        let range = name.syntax().text_range();
+        return Some(RangeInfo::new(range, def));
+    }
+    let name_ref =
+        sema.find_node_at_offset_with_descend::<ast::NameRef>(&syntax, position.offset)?;
+    let def = classify_name_ref(sema, &name_ref)?.definition(sema.db);
+    let range = name_ref.syntax().text_range();
+    Some(RangeInfo::new(range, def))
+}
+
+fn decl_access(def: &Definition, syntax: &SyntaxNode, range: TextRange) -> Option<ReferenceAccess> {
+    match def {
+        Definition::Local(_) | Definition::Field(_) => {}
+        _ => return None,
+    };
+
+    let stmt = find_node_at_offset::<ast::LetStmt>(syntax, range.start())?;
+    if stmt.initializer().is_some() {
+        let pat = stmt.pat()?;
+        if let ast::Pat::IdentPat(it) = pat {
+            if it.mut_token().is_some() {
+                return Some(ReferenceAccess::Write);
+            }
+        }
+    }
+
+    None
+}
+
+fn get_struct_def_name_for_struct_literal_search(
+    sema: &Semantics<RootDatabase>,
+    syntax: &SyntaxNode,
+    position: FilePosition,
+) -> Option<ast::Name> {
+    if let TokenAtOffset::Between(ref left, ref right) = syntax.token_at_offset(position.offset) {
+        if right.kind() != SyntaxKind::L_CURLY && right.kind() != SyntaxKind::L_PAREN {
+            return None;
+        }
+        if let Some(name) =
+            sema.find_node_at_offset_with_descend::<ast::Name>(&syntax, left.text_range().start())
+        {
+            return name.syntax().ancestors().find_map(ast::Struct::cast).and_then(|l| l.name());
+        }
+        if sema
+            .find_node_at_offset_with_descend::<ast::GenericParamList>(
+                &syntax,
+                left.text_range().start(),
+            )
+            .is_some()
+        {
+            return left.ancestors().find_map(ast::Struct::cast).and_then(|l| l.name());
+        }
+    }
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        mock_analysis::{analysis_and_position, MockAnalysis},
+        Declaration, Reference, ReferenceSearchResult, SearchScope,
+    };
+
+    #[test]
+    fn test_struct_literal_after_space() {
+        let refs = get_all_refs(
+            r#"
+struct Foo <|>{
+    a: i32,
+}
+impl Foo {
+    fn f() -> i32 { 42 }
+}
+fn main() {
+    let f: Foo;
+    f = Foo {a: Foo::f()};
+}
+"#,
+        );
+        check_result(
+            refs,
+            "Foo STRUCT FileId(1) 0..26 7..10 Other",
+            &["FileId(1) 101..104 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_struct_literal_before_space() {
+        let refs = get_all_refs(
+            r#"
+struct Foo<|> {}
+    fn main() {
+    let f: Foo;
+    f = Foo {};
+}
+"#,
+        );
+        check_result(
+            refs,
+            "Foo STRUCT FileId(1) 0..13 7..10 Other",
+            &["FileId(1) 41..44 Other", "FileId(1) 54..57 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_struct_literal_with_generic_type() {
+        let refs = get_all_refs(
+            r#"
+struct Foo<T> <|>{}
+    fn main() {
+    let f: Foo::<i32>;
+    f = Foo {};
+}
+"#,
+        );
+        check_result(
+            refs,
+            "Foo STRUCT FileId(1) 0..16 7..10 Other",
+            &["FileId(1) 64..67 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_struct_literal_for_tuple() {
+        let refs = get_all_refs(
+            r#"
+struct Foo<|>(i32);
+
+fn main() {
+    let f: Foo;
+    f = Foo(1);
+}
+"#,
+        );
+        check_result(
+            refs,
+            "Foo STRUCT FileId(1) 0..16 7..10 Other",
+            &["FileId(1) 54..57 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_for_local() {
+        let refs = get_all_refs(
+            r#"
+fn main() {
+    let mut i = 1;
+    let j = 1;
+    i = i<|> + j;
+
+    {
+        i = 0;
+    }
+
+    i = 5;
+}"#,
+        );
+        check_result(
+            refs,
+            "i IDENT_PAT FileId(1) 24..25 Other Write",
+            &[
+                "FileId(1) 50..51 Other Write",
+                "FileId(1) 54..55 Other Read",
+                "FileId(1) 76..77 Other Write",
+                "FileId(1) 94..95 Other Write",
+            ],
+        );
+    }
+
+    #[test]
+    fn search_filters_by_range() {
+        let refs = get_all_refs(
+            r#"
+fn foo() {
+    let spam<|> = 92;
+    spam + spam
+}
+fn bar() {
+    let spam = 92;
+    spam + spam
+}
+"#,
+        );
+        check_result(
+            refs,
+            "spam IDENT_PAT FileId(1) 19..23 Other",
+            &["FileId(1) 34..38 Other Read", "FileId(1) 41..45 Other Read"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_for_param_inside() {
+        let refs = get_all_refs(
+            r#"
+fn foo(i : u32) -> u32 {
+    i<|>
+}
+"#,
+        );
+        check_result(refs, "i IDENT_PAT FileId(1) 7..8 Other", &["FileId(1) 29..30 Other Read"]);
+    }
+
+    #[test]
+    fn test_find_all_refs_for_fn_param() {
+        let refs = get_all_refs(
+            r#"
+fn foo(i<|> : u32) -> u32 {
+    i
+}
+"#,
+        );
+        check_result(refs, "i IDENT_PAT FileId(1) 7..8 Other", &["FileId(1) 29..30 Other Read"]);
+    }
+
+    #[test]
+    fn test_find_all_refs_field_name() {
+        let refs = get_all_refs(
+            r#"
+//- /lib.rs
+struct Foo {
+    pub spam<|>: u32,
+}
+
+fn main(s: Foo) {
+    let f = s.spam;
+}
+"#,
+        );
+        check_result(
+            refs,
+            "spam RECORD_FIELD FileId(1) 17..30 21..25 Other",
+            &["FileId(1) 67..71 Other Read"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_impl_item_name() {
+        let refs = get_all_refs(
+            r#"
+struct Foo;
+impl Foo {
+    fn f<|>(&self) {  }
+}
+"#,
+        );
+        check_result(refs, "f FN FileId(1) 27..43 30..31 Other", &[]);
+    }
+
+    #[test]
+    fn test_find_all_refs_enum_var_name() {
+        let refs = get_all_refs(
+            r#"
+enum Foo {
+    A,
+    B<|>,
+    C,
+}
+"#,
+        );
+        check_result(refs, "B VARIANT FileId(1) 22..23 22..23 Other", &[]);
+    }
+
+    #[test]
+    fn test_find_all_refs_two_modules() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+//- /lib.rs
+pub mod foo;
+pub mod bar;
+
+fn f() {
+    let i = foo::Foo { n: 5 };
+}
+
+//- /foo.rs
+use crate::bar;
+
+pub struct Foo {
+    pub n: u32,
+}
+
+fn f() {
+    let i = bar::Bar { n: 5 };
+}
+
+//- /bar.rs
+use crate::foo;
+
+pub struct Bar {
+    pub n: u32,
+}
+
+fn f() {
+    let i = foo::Foo<|> { n: 5 };
+}
+"#,
+        );
+        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
+        check_result(
+            refs,
+            "Foo STRUCT FileId(2) 17..51 28..31 Other",
+            &["FileId(1) 53..56 StructLiteral", "FileId(3) 79..82 StructLiteral"],
+        );
+    }
+
+    // `mod foo;` is not in the results because `foo` is an `ast::Name`.
+    // So, there are two references: the first one is a definition of the `foo` module,
+    // which is the whole `foo.rs`, and the second one is in `use foo::Foo`.
+    #[test]
+    fn test_find_all_refs_decl_module() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+//- /lib.rs
+mod foo<|>;
+
+use foo::Foo;
+
+fn f() {
+    let i = Foo { n: 5 };
+}
+
+//- /foo.rs
+pub struct Foo {
+    pub n: u32,
+}
+"#,
+        );
+        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
+        check_result(refs, "foo SOURCE_FILE FileId(2) 0..35 Other", &["FileId(1) 14..17 Other"]);
+    }
+
+    #[test]
+    fn test_find_all_refs_super_mod_vis() {
+        let (analysis, pos) = analysis_and_position(
+            r#"
+//- /lib.rs
+mod foo;
+
+//- /foo.rs
+mod some;
+use some::Foo;
+
+fn f() {
+    let i = Foo { n: 5 };
+}
+
+//- /foo/some.rs
+pub(super) struct Foo<|> {
+    pub n: u32,
+}
+"#,
+        );
+        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
+        check_result(
+            refs,
+            "Foo STRUCT FileId(3) 0..41 18..21 Other",
+            &["FileId(2) 20..23 Other", "FileId(2) 47..50 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_with_scope() {
+        let code = r#"
+            //- /lib.rs
+            mod foo;
+            mod bar;
+
+            pub fn quux<|>() {}
+
+            //- /foo.rs
+            fn f() { super::quux(); }
+
+            //- /bar.rs
+            fn f() { super::quux(); }
+        "#;
+
+        let (mock, pos) = MockAnalysis::with_files_and_position(code);
+        let bar = mock.id_of("/bar.rs");
+        let analysis = mock.analysis();
+
+        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
+        check_result(
+            refs,
+            "quux FN FileId(1) 19..35 26..30 Other",
+            &["FileId(2) 16..20 StructLiteral", "FileId(3) 16..20 StructLiteral"],
+        );
+
+        let refs =
+            analysis.find_all_refs(pos, Some(SearchScope::single_file(bar))).unwrap().unwrap();
+        check_result(
+            refs,
+            "quux FN FileId(1) 19..35 26..30 Other",
+            &["FileId(3) 16..20 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_macro_def() {
+        let refs = get_all_refs(
+            r#"
+#[macro_export]
+macro_rules! m1<|> { () => (()) }
+
+fn foo() {
+    m1();
+    m1();
+}
+"#,
+        );
+        check_result(
+            refs,
+            "m1 MACRO_CALL FileId(1) 0..46 29..31 Other",
+            &["FileId(1) 63..65 StructLiteral", "FileId(1) 73..75 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_basic_highlight_read_write() {
+        let refs = get_all_refs(
+            r#"
+fn foo() {
+    let mut i<|> = 0;
+    i = i + 1;
+}
+"#,
+        );
+        check_result(
+            refs,
+            "i IDENT_PAT FileId(1) 23..24 Other Write",
+            &["FileId(1) 34..35 Other Write", "FileId(1) 38..39 Other Read"],
+        );
+    }
+
+    #[test]
+    fn test_basic_highlight_field_read_write() {
+        let refs = get_all_refs(
+            r#"
+struct S {
+    f: u32,
+}
+
+fn foo() {
+    let mut s = S{f: 0};
+    s.f<|> = 0;
+}
+"#,
+        );
+        check_result(
+            refs,
+            "f RECORD_FIELD FileId(1) 15..21 15..16 Other",
+            &["FileId(1) 55..56 Other Read", "FileId(1) 68..69 Other Write"],
+        );
+    }
+
+    #[test]
+    fn test_basic_highlight_decl_no_write() {
+        let refs = get_all_refs(
+            r#"
+fn foo() {
+    let i<|>;
+    i = 1;
+}
+"#,
+        );
+        check_result(refs, "i IDENT_PAT FileId(1) 19..20 Other", &["FileId(1) 26..27 Other Write"]);
+    }
+
+    #[test]
+    fn test_find_struct_function_refs_outside_module() {
+        let refs = get_all_refs(
+            r#"
+mod foo {
+    pub struct Foo;
+
+    impl Foo {
+        pub fn new<|>() -> Foo {
+            Foo
+        }
+    }
+}
+
+fn main() {
+    let _f = foo::Foo::new();
+}
+"#,
+        );
+        check_result(
+            refs,
+            "new FN FileId(1) 54..101 61..64 Other",
+            &["FileId(1) 146..149 StructLiteral"],
+        );
+    }
+
+    #[test]
+    fn test_find_all_refs_nested_module() {
+        let code = r#"
+            //- /lib.rs
+            mod foo {
+                mod bar;
+            }
+
+            fn f<|>() {}
+
+            //- /foo/bar.rs
+            use crate::f;
+
+            fn g() {
+                f();
+            }
+        "#;
+
+        let (analysis, pos) = analysis_and_position(code);
+        let refs = analysis.find_all_refs(pos, None).unwrap().unwrap();
+        check_result(
+            refs,
+            "f FN FileId(1) 26..35 29..30 Other",
+            &["FileId(2) 11..12 Other", "FileId(2) 28..29 StructLiteral"],
+        );
+    }
+
+    fn get_all_refs(ra_fixture: &str) -> ReferenceSearchResult {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        analysis.find_all_refs(position, None).unwrap().unwrap()
+    }
+
+    fn check_result(res: ReferenceSearchResult, expected_decl: &str, expected_refs: &[&str]) {
+        res.declaration().assert_match(expected_decl);
+        assert_eq!(res.references.len(), expected_refs.len());
+        res.references()
+            .iter()
+            .enumerate()
+            .for_each(|(i, r)| ref_assert_match(r, expected_refs[i]));
+    }
+
+    impl Declaration {
+        fn debug_render(&self) -> String {
+            let mut s = format!("{} {:?}", self.nav.debug_render(), self.kind);
+            if let Some(access) = self.access {
+                s.push_str(&format!(" {:?}", access));
+            }
+            s
+        }
+
+        fn assert_match(&self, expected: &str) {
+            let actual = self.debug_render();
+            test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
+        }
+    }
+
+    fn ref_debug_render(r: &Reference) -> String {
+        let mut s = format!("{:?} {:?} {:?}", r.file_range.file_id, r.file_range.range, r.kind);
+        if let Some(access) = r.access {
+            s.push_str(&format!(" {:?}", access));
+        }
+        s
+    }
+
+    fn ref_assert_match(r: &Reference, expected: &str) {
+        let actual = ref_debug_render(r);
+        test_utils::assert_eq_text!(expected.trim(), actual.trim(),);
+    }
+}
diff --git a/crates/ide/src/references/rename.rs b/crates/ide/src/references/rename.rs
new file mode 100644
index 000000000..301629763
--- /dev/null
+++ b/crates/ide/src/references/rename.rs
@@ -0,0 +1,1010 @@
+//! FIXME: write short doc here
+
+use base_db::SourceDatabaseExt;
+use hir::{Module, ModuleDef, ModuleSource, Semantics};
+use ide_db::{
+    defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
+    RootDatabase,
+};
+use std::convert::TryInto;
+use syntax::{
+    algo::find_node_at_offset,
+    ast::{self, NameOwner},
+    lex_single_valid_syntax_kind, match_ast, AstNode, SyntaxKind, SyntaxNode, SyntaxToken,
+};
+use test_utils::mark;
+use text_edit::TextEdit;
+
+use crate::{
+    references::find_all_refs, FilePosition, FileSystemEdit, RangeInfo, Reference, ReferenceKind,
+    SourceChange, SourceFileEdit, TextRange, TextSize,
+};
+
+pub(crate) fn rename(
+    db: &RootDatabase,
+    position: FilePosition,
+    new_name: &str,
+) -> Option<RangeInfo<SourceChange>> {
+    let sema = Semantics::new(db);
+
+    match lex_single_valid_syntax_kind(new_name)? {
+        SyntaxKind::IDENT | SyntaxKind::UNDERSCORE => (),
+        SyntaxKind::SELF_KW => return rename_to_self(&sema, position),
+        _ => return None,
+    }
+
+    let source_file = sema.parse(position.file_id);
+    let syntax = source_file.syntax();
+    if let Some(module) = find_module_at_offset(&sema, position, syntax) {
+        rename_mod(&sema, position, module, new_name)
+    } else if let Some(self_token) =
+        syntax.token_at_offset(position.offset).find(|t| t.kind() == SyntaxKind::SELF_KW)
+    {
+        rename_self_to_param(&sema, position, self_token, new_name)
+    } else {
+        rename_reference(&sema, position, new_name)
+    }
+}
+
+fn find_module_at_offset(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    syntax: &SyntaxNode,
+) -> Option<Module> {
+    let ident = syntax.token_at_offset(position.offset).find(|t| t.kind() == SyntaxKind::IDENT)?;
+
+    let module = match_ast! {
+        match (ident.parent()) {
+            ast::NameRef(name_ref) => {
+                match classify_name_ref(sema, &name_ref)? {
+                    NameRefClass::Definition(Definition::ModuleDef(ModuleDef::Module(module))) => module,
+                    _ => return None,
+                }
+            },
+            ast::Name(name) => {
+                match classify_name(&sema, &name)? {
+                    NameClass::Definition(Definition::ModuleDef(ModuleDef::Module(module))) => module,
+                    _ => return None,
+                }
+            },
+            _ => return None,
+        }
+    };
+
+    Some(module)
+}
+
+fn source_edit_from_reference(reference: Reference, new_name: &str) -> SourceFileEdit {
+    let mut replacement_text = String::new();
+    let file_id = reference.file_range.file_id;
+    let range = match reference.kind {
+        ReferenceKind::FieldShorthandForField => {
+            mark::hit!(test_rename_struct_field_for_shorthand);
+            replacement_text.push_str(new_name);
+            replacement_text.push_str(": ");
+            TextRange::new(reference.file_range.range.start(), reference.file_range.range.start())
+        }
+        ReferenceKind::FieldShorthandForLocal => {
+            mark::hit!(test_rename_local_for_field_shorthand);
+            replacement_text.push_str(": ");
+            replacement_text.push_str(new_name);
+            TextRange::new(reference.file_range.range.end(), reference.file_range.range.end())
+        }
+        _ => {
+            replacement_text.push_str(new_name);
+            reference.file_range.range
+        }
+    };
+    SourceFileEdit { file_id, edit: TextEdit::replace(range, replacement_text) }
+}
+
+fn rename_mod(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    module: Module,
+    new_name: &str,
+) -> Option<RangeInfo<SourceChange>> {
+    let mut source_file_edits = Vec::new();
+    let mut file_system_edits = Vec::new();
+
+    let src = module.definition_source(sema.db);
+    let file_id = src.file_id.original_file(sema.db);
+    match src.value {
+        ModuleSource::SourceFile(..) => {
+            // mod is defined in path/to/dir/mod.rs
+            let dst = if module.is_mod_rs(sema.db) {
+                format!("../{}/mod.rs", new_name)
+            } else {
+                format!("{}.rs", new_name)
+            };
+            let move_file = FileSystemEdit::MoveFile { src: file_id, anchor: file_id, dst };
+            file_system_edits.push(move_file);
+        }
+        ModuleSource::Module(..) => {}
+    }
+
+    if let Some(src) = module.declaration_source(sema.db) {
+        let file_id = src.file_id.original_file(sema.db);
+        let name = src.value.name()?;
+        let edit = SourceFileEdit {
+            file_id,
+            edit: TextEdit::replace(name.syntax().text_range(), new_name.into()),
+        };
+        source_file_edits.push(edit);
+    }
+
+    let RangeInfo { range, info: refs } = find_all_refs(sema, position, None)?;
+    let ref_edits = refs
+        .references
+        .into_iter()
+        .map(|reference| source_edit_from_reference(reference, new_name));
+    source_file_edits.extend(ref_edits);
+
+    Some(RangeInfo::new(range, SourceChange::from_edits(source_file_edits, file_system_edits)))
+}
+
+fn rename_to_self(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+) -> Option<RangeInfo<SourceChange>> {
+    let source_file = sema.parse(position.file_id);
+    let syn = source_file.syntax();
+
+    let fn_def = find_node_at_offset::<ast::Fn>(syn, position.offset)?;
+    let params = fn_def.param_list()?;
+    if params.self_param().is_some() {
+        return None; // method already has self param
+    }
+    let first_param = params.params().next()?;
+    let mutable = match first_param.ty() {
+        Some(ast::Type::RefType(rt)) => rt.mut_token().is_some(),
+        _ => return None, // not renaming other types
+    };
+
+    let RangeInfo { range, info: refs } = find_all_refs(sema, position, None)?;
+
+    let param_range = first_param.syntax().text_range();
+    let (param_ref, usages): (Vec<Reference>, Vec<Reference>) = refs
+        .into_iter()
+        .partition(|reference| param_range.intersect(reference.file_range.range).is_some());
+
+    if param_ref.is_empty() {
+        return None;
+    }
+
+    let mut edits = usages
+        .into_iter()
+        .map(|reference| source_edit_from_reference(reference, "self"))
+        .collect::<Vec<_>>();
+
+    edits.push(SourceFileEdit {
+        file_id: position.file_id,
+        edit: TextEdit::replace(
+            param_range,
+            String::from(if mutable { "&mut self" } else { "&self" }),
+        ),
+    });
+
+    Some(RangeInfo::new(range, SourceChange::from(edits)))
+}
+
+fn text_edit_from_self_param(
+    syn: &SyntaxNode,
+    self_param: &ast::SelfParam,
+    new_name: &str,
+) -> Option<TextEdit> {
+    fn target_type_name(impl_def: &ast::Impl) -> Option<String> {
+        if let Some(ast::Type::PathType(p)) = impl_def.self_ty() {
+            return Some(p.path()?.segment()?.name_ref()?.text().to_string());
+        }
+        None
+    }
+
+    let impl_def = find_node_at_offset::<ast::Impl>(syn, self_param.syntax().text_range().start())?;
+    let type_name = target_type_name(&impl_def)?;
+
+    let mut replacement_text = String::from(new_name);
+    replacement_text.push_str(": ");
+    replacement_text.push_str(self_param.mut_token().map_or("&", |_| "&mut "));
+    replacement_text.push_str(type_name.as_str());
+
+    Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
+}
+
+fn rename_self_to_param(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    self_token: SyntaxToken,
+    new_name: &str,
+) -> Option<RangeInfo<SourceChange>> {
+    let source_file = sema.parse(position.file_id);
+    let syn = source_file.syntax();
+
+    let text = sema.db.file_text(position.file_id);
+    let fn_def = find_node_at_offset::<ast::Fn>(syn, position.offset)?;
+    let search_range = fn_def.syntax().text_range();
+
+    let mut edits: Vec<SourceFileEdit> = vec![];
+
+    for (idx, _) in text.match_indices("self") {
+        let offset: TextSize = idx.try_into().unwrap();
+        if !search_range.contains_inclusive(offset) {
+            continue;
+        }
+        if let Some(ref usage) =
+            syn.token_at_offset(offset).find(|t| t.kind() == SyntaxKind::SELF_KW)
+        {
+            let edit = if let Some(ref self_param) = ast::SelfParam::cast(usage.parent()) {
+                text_edit_from_self_param(syn, self_param, new_name)?
+            } else {
+                TextEdit::replace(usage.text_range(), String::from(new_name))
+            };
+            edits.push(SourceFileEdit { file_id: position.file_id, edit });
+        }
+    }
+
+    let range = ast::SelfParam::cast(self_token.parent())
+        .map_or(self_token.text_range(), |p| p.syntax().text_range());
+
+    Some(RangeInfo::new(range, SourceChange::from(edits)))
+}
+
+fn rename_reference(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    new_name: &str,
+) -> Option<RangeInfo<SourceChange>> {
+    let RangeInfo { range, info: refs } = find_all_refs(sema, position, None)?;
+
+    let edit = refs
+        .into_iter()
+        .map(|reference| source_edit_from_reference(reference, new_name))
+        .collect::<Vec<_>>();
+
+    if edit.is_empty() {
+        return None;
+    }
+
+    Some(RangeInfo::new(range, SourceChange::from(edit)))
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use stdx::trim_indent;
+    use test_utils::{assert_eq_text, mark};
+    use text_edit::TextEdit;
+
+    use crate::{mock_analysis::analysis_and_position, FileId};
+
+    fn check(new_name: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
+        let ra_fixture_after = &trim_indent(ra_fixture_after);
+        let (analysis, position) = analysis_and_position(ra_fixture_before);
+        let source_change = analysis.rename(position, new_name).unwrap();
+        let mut text_edit_builder = TextEdit::builder();
+        let mut file_id: Option<FileId> = None;
+        if let Some(change) = source_change {
+            for edit in change.info.source_file_edits {
+                file_id = Some(edit.file_id);
+                for indel in edit.edit.into_iter() {
+                    text_edit_builder.replace(indel.delete, indel.insert);
+                }
+            }
+        }
+        let mut result = analysis.file_text(file_id.unwrap()).unwrap().to_string();
+        text_edit_builder.finish().apply(&mut result);
+        assert_eq_text!(ra_fixture_after, &*result);
+    }
+
+    fn check_expect(new_name: &str, ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let source_change = analysis.rename(position, new_name).unwrap().unwrap();
+        expect.assert_debug_eq(&source_change)
+    }
+
+    #[test]
+    fn test_rename_to_underscore() {
+        check("_", r#"fn main() { let i<|> = 1; }"#, r#"fn main() { let _ = 1; }"#);
+    }
+
+    #[test]
+    fn test_rename_to_raw_identifier() {
+        check("r#fn", r#"fn main() { let i<|> = 1; }"#, r#"fn main() { let r#fn = 1; }"#);
+    }
+
+    #[test]
+    fn test_rename_to_invalid_identifier() {
+        let (analysis, position) = analysis_and_position(r#"fn main() { let i<|> = 1; }"#);
+        let new_name = "invalid!";
+        let source_change = analysis.rename(position, new_name).unwrap();
+        assert!(source_change.is_none());
+    }
+
+    #[test]
+    fn test_rename_for_local() {
+        check(
+            "k",
+            r#"
+fn main() {
+    let mut i = 1;
+    let j = 1;
+    i = i<|> + j;
+
+    { i = 0; }
+
+    i = 5;
+}
+"#,
+            r#"
+fn main() {
+    let mut k = 1;
+    let j = 1;
+    k = k + j;
+
+    { k = 0; }
+
+    k = 5;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_for_macro_args() {
+        check(
+            "b",
+            r#"
+macro_rules! foo {($i:ident) => {$i} }
+fn main() {
+    let a<|> = "test";
+    foo!(a);
+}
+"#,
+            r#"
+macro_rules! foo {($i:ident) => {$i} }
+fn main() {
+    let b = "test";
+    foo!(b);
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_for_macro_args_rev() {
+        check(
+            "b",
+            r#"
+macro_rules! foo {($i:ident) => {$i} }
+fn main() {
+    let a = "test";
+    foo!(a<|>);
+}
+"#,
+            r#"
+macro_rules! foo {($i:ident) => {$i} }
+fn main() {
+    let b = "test";
+    foo!(b);
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_for_macro_define_fn() {
+        check(
+            "bar",
+            r#"
+macro_rules! define_fn {($id:ident) => { fn $id{} }}
+define_fn!(foo);
+fn main() {
+    fo<|>o();
+}
+"#,
+            r#"
+macro_rules! define_fn {($id:ident) => { fn $id{} }}
+define_fn!(bar);
+fn main() {
+    bar();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_for_macro_define_fn_rev() {
+        check(
+            "bar",
+            r#"
+macro_rules! define_fn {($id:ident) => { fn $id{} }}
+define_fn!(fo<|>o);
+fn main() {
+    foo();
+}
+"#,
+            r#"
+macro_rules! define_fn {($id:ident) => { fn $id{} }}
+define_fn!(bar);
+fn main() {
+    bar();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_for_param_inside() {
+        check("j", r#"fn foo(i : u32) -> u32 { i<|> }"#, r#"fn foo(j : u32) -> u32 { j }"#);
+    }
+
+    #[test]
+    fn test_rename_refs_for_fn_param() {
+        check("j", r#"fn foo(i<|> : u32) -> u32 { i }"#, r#"fn foo(j : u32) -> u32 { j }"#);
+    }
+
+    #[test]
+    fn test_rename_for_mut_param() {
+        check("j", r#"fn foo(mut i<|> : u32) -> u32 { i }"#, r#"fn foo(mut j : u32) -> u32 { j }"#);
+    }
+
+    #[test]
+    fn test_rename_struct_field() {
+        check(
+            "j",
+            r#"
+struct Foo { i<|>: i32 }
+
+impl Foo {
+    fn new(i: i32) -> Self {
+        Self { i: i }
+    }
+}
+"#,
+            r#"
+struct Foo { j: i32 }
+
+impl Foo {
+    fn new(i: i32) -> Self {
+        Self { j: i }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_struct_field_for_shorthand() {
+        mark::check!(test_rename_struct_field_for_shorthand);
+        check(
+            "j",
+            r#"
+struct Foo { i<|>: i32 }
+
+impl Foo {
+    fn new(i: i32) -> Self {
+        Self { i }
+    }
+}
+"#,
+            r#"
+struct Foo { j: i32 }
+
+impl Foo {
+    fn new(i: i32) -> Self {
+        Self { j: i }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_local_for_field_shorthand() {
+        mark::check!(test_rename_local_for_field_shorthand);
+        check(
+            "j",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn new(i<|>: i32) -> Self {
+        Self { i }
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn new(j: i32) -> Self {
+        Self { i: j }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_field_shorthand_correct_struct() {
+        check(
+            "j",
+            r#"
+struct Foo { i<|>: i32 }
+struct Bar { i: i32 }
+
+impl Bar {
+    fn new(i: i32) -> Self {
+        Self { i }
+    }
+}
+"#,
+            r#"
+struct Foo { j: i32 }
+struct Bar { i: i32 }
+
+impl Bar {
+    fn new(i: i32) -> Self {
+        Self { i }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_shadow_local_for_struct_shorthand() {
+        check(
+            "j",
+            r#"
+struct Foo { i: i32 }
+
+fn baz(i<|>: i32) -> Self {
+     let x = Foo { i };
+     {
+         let i = 0;
+         Foo { i }
+     }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+fn baz(j: i32) -> Self {
+     let x = Foo { i: j };
+     {
+         let i = 0;
+         Foo { i }
+     }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_mod() {
+        check_expect(
+            "foo2",
+            r#"
+//- /lib.rs
+mod bar;
+
+//- /bar.rs
+mod foo<|>;
+
+//- /bar/foo.rs
+// empty
+"#,
+            expect![[r#"
+                RangeInfo {
+                    range: 4..7,
+                    info: SourceChange {
+                        source_file_edits: [
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    2,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "foo2",
+                                            delete: 4..7,
+                                        },
+                                    ],
+                                },
+                            },
+                        ],
+                        file_system_edits: [
+                            MoveFile {
+                                src: FileId(
+                                    3,
+                                ),
+                                anchor: FileId(
+                                    3,
+                                ),
+                                dst: "foo2.rs",
+                            },
+                        ],
+                        is_snippet: false,
+                    },
+                }
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_rename_mod_in_use_tree() {
+        check_expect(
+            "quux",
+            r#"
+//- /main.rs
+pub mod foo;
+pub mod bar;
+fn main() {}
+
+//- /foo.rs
+pub struct FooContent;
+
+//- /bar.rs
+use crate::foo<|>::FooContent;
+"#,
+            expect![[r#"
+                RangeInfo {
+                    range: 11..14,
+                    info: SourceChange {
+                        source_file_edits: [
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "quux",
+                                            delete: 8..11,
+                                        },
+                                    ],
+                                },
+                            },
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    3,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "quux",
+                                            delete: 11..14,
+                                        },
+                                    ],
+                                },
+                            },
+                        ],
+                        file_system_edits: [
+                            MoveFile {
+                                src: FileId(
+                                    2,
+                                ),
+                                anchor: FileId(
+                                    2,
+                                ),
+                                dst: "quux.rs",
+                            },
+                        ],
+                        is_snippet: false,
+                    },
+                }
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_rename_mod_in_dir() {
+        check_expect(
+            "foo2",
+            r#"
+//- /lib.rs
+mod fo<|>o;
+//- /foo/mod.rs
+// emtpy
+"#,
+            expect![[r#"
+                RangeInfo {
+                    range: 4..7,
+                    info: SourceChange {
+                        source_file_edits: [
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "foo2",
+                                            delete: 4..7,
+                                        },
+                                    ],
+                                },
+                            },
+                        ],
+                        file_system_edits: [
+                            MoveFile {
+                                src: FileId(
+                                    2,
+                                ),
+                                anchor: FileId(
+                                    2,
+                                ),
+                                dst: "../foo2/mod.rs",
+                            },
+                        ],
+                        is_snippet: false,
+                    },
+                }
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_rename_unusually_nested_mod() {
+        check_expect(
+            "bar",
+            r#"
+//- /lib.rs
+mod outer { mod fo<|>o; }
+
+//- /outer/foo.rs
+// emtpy
+"#,
+            expect![[r#"
+                RangeInfo {
+                    range: 16..19,
+                    info: SourceChange {
+                        source_file_edits: [
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "bar",
+                                            delete: 16..19,
+                                        },
+                                    ],
+                                },
+                            },
+                        ],
+                        file_system_edits: [
+                            MoveFile {
+                                src: FileId(
+                                    2,
+                                ),
+                                anchor: FileId(
+                                    2,
+                                ),
+                                dst: "bar.rs",
+                            },
+                        ],
+                        is_snippet: false,
+                    },
+                }
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_module_rename_in_path() {
+        check(
+            "baz",
+            r#"
+mod <|>foo { pub fn bar() {} }
+
+fn main() { foo::bar(); }
+"#,
+            r#"
+mod baz { pub fn bar() {} }
+
+fn main() { baz::bar(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_mod_filename_and_path() {
+        check_expect(
+            "foo2",
+            r#"
+//- /lib.rs
+mod bar;
+fn f() {
+    bar::foo::fun()
+}
+
+//- /bar.rs
+pub mod foo<|>;
+
+//- /bar/foo.rs
+// pub fn fun() {}
+"#,
+            expect![[r#"
+                RangeInfo {
+                    range: 8..11,
+                    info: SourceChange {
+                        source_file_edits: [
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    2,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "foo2",
+                                            delete: 8..11,
+                                        },
+                                    ],
+                                },
+                            },
+                            SourceFileEdit {
+                                file_id: FileId(
+                                    1,
+                                ),
+                                edit: TextEdit {
+                                    indels: [
+                                        Indel {
+                                            insert: "foo2",
+                                            delete: 27..30,
+                                        },
+                                    ],
+                                },
+                            },
+                        ],
+                        file_system_edits: [
+                            MoveFile {
+                                src: FileId(
+                                    3,
+                                ),
+                                anchor: FileId(
+                                    3,
+                                ),
+                                dst: "foo2.rs",
+                            },
+                        ],
+                        is_snippet: false,
+                    },
+                }
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_enum_variant_from_module_1() {
+        check(
+            "Baz",
+            r#"
+mod foo {
+    pub enum Foo { Bar<|> }
+}
+
+fn func(f: foo::Foo) {
+    match f {
+        foo::Foo::Bar => {}
+    }
+}
+"#,
+            r#"
+mod foo {
+    pub enum Foo { Baz }
+}
+
+fn func(f: foo::Foo) {
+    match f {
+        foo::Foo::Baz => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_enum_variant_from_module_2() {
+        check(
+            "baz",
+            r#"
+mod foo {
+    pub struct Foo { pub bar<|>: uint }
+}
+
+fn foo(f: foo::Foo) {
+    let _ = f.bar;
+}
+"#,
+            r#"
+mod foo {
+    pub struct Foo { pub baz: uint }
+}
+
+fn foo(f: foo::Foo) {
+    let _ = f.baz;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_parameter_to_self() {
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(foo<|>: &mut Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(&mut self) -> i32 {
+        self.i
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_self_to_parameter() {
+        check(
+            "foo",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(&mut <|>self) -> i32 {
+        self.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(foo: &mut Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_self_in_path_to_parameter() {
+        check(
+            "foo",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(&self) -> i32 {
+        let self_var = 1;
+        self<|>.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(foo: &Foo) -> i32 {
+        let self_var = 1;
+        foo.i
+    }
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
new file mode 100644
index 000000000..4139f329e
--- /dev/null
+++ b/crates/ide/src/runnables.rs
@@ -0,0 +1,883 @@
+use std::fmt;
+
+use cfg::CfgExpr;
+use hir::{AsAssocItem, Attrs, HirFileId, InFile, Semantics};
+use ide_db::RootDatabase;
+use itertools::Itertools;
+use syntax::{
+    ast::{self, AstNode, AttrsOwner, DocCommentsOwner, ModuleItemOwner, NameOwner},
+    match_ast, SyntaxNode,
+};
+
+use crate::{display::ToNav, FileId, NavigationTarget};
+
+#[derive(Debug, Clone)]
+pub struct Runnable {
+    pub nav: NavigationTarget,
+    pub kind: RunnableKind,
+    pub cfg_exprs: Vec<CfgExpr>,
+}
+
+#[derive(Debug, Clone)]
+pub enum TestId {
+    Name(String),
+    Path(String),
+}
+
+impl fmt::Display for TestId {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TestId::Name(name) => write!(f, "{}", name),
+            TestId::Path(path) => write!(f, "{}", path),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum RunnableKind {
+    Test { test_id: TestId, attr: TestAttr },
+    TestMod { path: String },
+    Bench { test_id: TestId },
+    DocTest { test_id: TestId },
+    Bin,
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct RunnableAction {
+    pub run_title: &'static str,
+    pub debugee: bool,
+}
+
+const TEST: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run Test", debugee: true };
+const DOCTEST: RunnableAction =
+    RunnableAction { run_title: "▶\u{fe0e} Run Doctest", debugee: false };
+const BENCH: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run Bench", debugee: true };
+const BIN: RunnableAction = RunnableAction { run_title: "▶\u{fe0e} Run", debugee: true };
+
+impl Runnable {
+    // test package::module::testname
+    pub fn label(&self, target: Option<String>) -> String {
+        match &self.kind {
+            RunnableKind::Test { test_id, .. } => format!("test {}", test_id),
+            RunnableKind::TestMod { path } => format!("test-mod {}", path),
+            RunnableKind::Bench { test_id } => format!("bench {}", test_id),
+            RunnableKind::DocTest { test_id, .. } => format!("doctest {}", test_id),
+            RunnableKind::Bin => {
+                target.map_or_else(|| "run binary".to_string(), |t| format!("run {}", t))
+            }
+        }
+    }
+
+    pub fn action(&self) -> &'static RunnableAction {
+        match &self.kind {
+            RunnableKind::Test { .. } | RunnableKind::TestMod { .. } => &TEST,
+            RunnableKind::DocTest { .. } => &DOCTEST,
+            RunnableKind::Bench { .. } => &BENCH,
+            RunnableKind::Bin => &BIN,
+        }
+    }
+}
+
+// Feature: Run
+//
+// Shows a popup suggesting to run a test/benchmark/binary **at the current cursor
+// location**. Super useful for repeatedly running just a single test. Do bind this
+// to a shortcut!
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Run**
+// |===
+pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
+    let sema = Semantics::new(db);
+    let source_file = sema.parse(file_id);
+    source_file.syntax().descendants().filter_map(|i| runnable(&sema, i, file_id)).collect()
+}
+
+pub(crate) fn runnable(
+    sema: &Semantics<RootDatabase>,
+    item: SyntaxNode,
+    file_id: FileId,
+) -> Option<Runnable> {
+    match_ast! {
+        match item {
+            ast::Fn(it) => runnable_fn(sema, it, file_id),
+            ast::Module(it) => runnable_mod(sema, it, file_id),
+            _ => None,
+        }
+    }
+}
+
+fn runnable_fn(
+    sema: &Semantics<RootDatabase>,
+    fn_def: ast::Fn,
+    file_id: FileId,
+) -> Option<Runnable> {
+    let name_string = fn_def.name()?.text().to_string();
+
+    let kind = if name_string == "main" {
+        RunnableKind::Bin
+    } else {
+        let test_id = match sema.to_def(&fn_def).map(|def| def.module(sema.db)) {
+            Some(module) => {
+                let def = sema.to_def(&fn_def)?;
+                let impl_trait_name = def.as_assoc_item(sema.db).and_then(|assoc_item| {
+                    match assoc_item.container(sema.db) {
+                        hir::AssocItemContainer::Trait(trait_item) => {
+                            Some(trait_item.name(sema.db).to_string())
+                        }
+                        hir::AssocItemContainer::ImplDef(impl_def) => impl_def
+                            .target_ty(sema.db)
+                            .as_adt()
+                            .map(|adt| adt.name(sema.db).to_string()),
+                    }
+                });
+
+                let path_iter = module
+                    .path_to_root(sema.db)
+                    .into_iter()
+                    .rev()
+                    .filter_map(|it| it.name(sema.db))
+                    .map(|name| name.to_string());
+
+                let path = if let Some(impl_trait_name) = impl_trait_name {
+                    path_iter
+                        .chain(std::iter::once(impl_trait_name))
+                        .chain(std::iter::once(name_string))
+                        .join("::")
+                } else {
+                    path_iter.chain(std::iter::once(name_string)).join("::")
+                };
+
+                TestId::Path(path)
+            }
+            None => TestId::Name(name_string),
+        };
+
+        if has_test_related_attribute(&fn_def) {
+            let attr = TestAttr::from_fn(&fn_def);
+            RunnableKind::Test { test_id, attr }
+        } else if fn_def.has_atom_attr("bench") {
+            RunnableKind::Bench { test_id }
+        } else if has_doc_test(&fn_def) {
+            RunnableKind::DocTest { test_id }
+        } else {
+            return None;
+        }
+    };
+
+    let attrs = Attrs::from_attrs_owner(sema.db, InFile::new(HirFileId::from(file_id), &fn_def));
+    let cfg_exprs = attrs.cfg().collect();
+
+    let nav = if let RunnableKind::DocTest { .. } = kind {
+        NavigationTarget::from_doc_commented(
+            sema.db,
+            InFile::new(file_id.into(), &fn_def),
+            InFile::new(file_id.into(), &fn_def),
+        )
+    } else {
+        NavigationTarget::from_named(sema.db, InFile::new(file_id.into(), &fn_def))
+    };
+    Some(Runnable { nav, kind, cfg_exprs })
+}
+
+#[derive(Debug, Copy, Clone)]
+pub struct TestAttr {
+    pub ignore: bool,
+}
+
+impl TestAttr {
+    fn from_fn(fn_def: &ast::Fn) -> TestAttr {
+        let ignore = fn_def
+            .attrs()
+            .filter_map(|attr| attr.simple_name())
+            .any(|attribute_text| attribute_text == "ignore");
+        TestAttr { ignore }
+    }
+}
+
+/// This is a method with a heuristics to support test methods annotated with custom test annotations, such as
+/// `#[test_case(...)]`, `#[tokio::test]` and similar.
+/// Also a regular `#[test]` annotation is supported.
+///
+/// It may produce false positives, for example, `#[wasm_bindgen_test]` requires a different command to run the test,
+/// but it's better than not to have the runnables for the tests at all.
+fn has_test_related_attribute(fn_def: &ast::Fn) -> bool {
+    fn_def
+        .attrs()
+        .filter_map(|attr| attr.path())
+        .map(|path| path.syntax().to_string().to_lowercase())
+        .any(|attribute_text| attribute_text.contains("test"))
+}
+
+fn has_doc_test(fn_def: &ast::Fn) -> bool {
+    fn_def.doc_comment_text().map_or(false, |comment| comment.contains("```"))
+}
+
+fn runnable_mod(
+    sema: &Semantics<RootDatabase>,
+    module: ast::Module,
+    file_id: FileId,
+) -> Option<Runnable> {
+    if !has_test_function_or_multiple_test_submodules(&module) {
+        return None;
+    }
+    let module_def = sema.to_def(&module)?;
+
+    let path = module_def
+        .path_to_root(sema.db)
+        .into_iter()
+        .rev()
+        .filter_map(|it| it.name(sema.db))
+        .join("::");
+
+    let attrs = Attrs::from_attrs_owner(sema.db, InFile::new(HirFileId::from(file_id), &module));
+    let cfg_exprs = attrs.cfg().collect();
+    let nav = module_def.to_nav(sema.db);
+    Some(Runnable { nav, kind: RunnableKind::TestMod { path }, cfg_exprs })
+}
+
+// We could create runnables for modules with number_of_test_submodules > 0,
+// but that bloats the runnables for no real benefit, since all tests can be run by the submodule already
+fn has_test_function_or_multiple_test_submodules(module: &ast::Module) -> bool {
+    if let Some(item_list) = module.item_list() {
+        let mut number_of_test_submodules = 0;
+
+        for item in item_list.items() {
+            match item {
+                ast::Item::Fn(f) => {
+                    if has_test_related_attribute(&f) {
+                        return true;
+                    }
+                }
+                ast::Item::Module(submodule) => {
+                    if has_test_function_or_multiple_test_submodules(&submodule) {
+                        number_of_test_submodules += 1;
+                    }
+                }
+                _ => (),
+            }
+        }
+
+        number_of_test_submodules > 1
+    } else {
+        false
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+
+    use crate::mock_analysis::analysis_and_position;
+
+    use super::{RunnableAction, BENCH, BIN, DOCTEST, TEST};
+
+    fn check(
+        ra_fixture: &str,
+        // FIXME: fold this into `expect` as well
+        actions: &[&RunnableAction],
+        expect: Expect,
+    ) {
+        let (analysis, position) = analysis_and_position(ra_fixture);
+        let runnables = analysis.runnables(position.file_id).unwrap();
+        expect.assert_debug_eq(&runnables);
+        assert_eq!(
+            actions,
+            runnables.into_iter().map(|it| it.action()).collect::<Vec<_>>().as_slice()
+        );
+    }
+
+    #[test]
+    fn test_runnables() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+fn main() {}
+
+#[test]
+fn test_foo() {}
+
+#[test]
+#[ignore]
+fn test_foo() {}
+
+#[bench]
+fn bench() {}
+"#,
+            &[&BIN, &TEST, &TEST, &BENCH],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..13,
+                            focus_range: Some(
+                                4..8,
+                            ),
+                            name: "main",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Bin,
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 15..39,
+                            focus_range: Some(
+                                26..34,
+                            ),
+                            name: "test_foo",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "test_foo",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 41..75,
+                            focus_range: Some(
+                                62..70,
+                            ),
+                            name: "test_foo",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "test_foo",
+                            ),
+                            attr: TestAttr {
+                                ignore: true,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 77..99,
+                            focus_range: Some(
+                                89..94,
+                            ),
+                            name: "bench",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Bench {
+                            test_id: Path(
+                                "bench",
+                            ),
+                        },
+                        cfg_exprs: [],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_doc_test() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+fn main() {}
+
+/// ```
+/// let x = 5;
+/// ```
+fn foo() {}
+"#,
+            &[&BIN, &DOCTEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..13,
+                            focus_range: Some(
+                                4..8,
+                            ),
+                            name: "main",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Bin,
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 15..57,
+                            focus_range: None,
+                            name: "foo",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: DocTest {
+                            test_id: Path(
+                                "foo",
+                            ),
+                        },
+                        cfg_exprs: [],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_doc_test_in_impl() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+fn main() {}
+
+struct Data;
+impl Data {
+    /// ```
+    /// let x = 5;
+    /// ```
+    fn foo() {}
+}
+"#,
+            &[&BIN, &DOCTEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..13,
+                            focus_range: Some(
+                                4..8,
+                            ),
+                            name: "main",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Bin,
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 44..98,
+                            focus_range: None,
+                            name: "foo",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: DocTest {
+                            test_id: Path(
+                                "Data::foo",
+                            ),
+                        },
+                        cfg_exprs: [],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_module() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+mod test_mod {
+    #[test]
+    fn test_foo1() {}
+}
+"#,
+            &[&TEST, &TEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..51,
+                            focus_range: Some(
+                                5..13,
+                            ),
+                            name: "test_mod",
+                            kind: MODULE,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "test_mod",
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 20..49,
+                            focus_range: Some(
+                                35..44,
+                            ),
+                            name: "test_foo1",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "test_mod::test_foo1",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn only_modules_with_test_functions_or_more_than_one_test_submodule_have_runners() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+mod root_tests {
+    mod nested_tests_0 {
+        mod nested_tests_1 {
+            #[test]
+            fn nested_test_11() {}
+
+            #[test]
+            fn nested_test_12() {}
+        }
+
+        mod nested_tests_2 {
+            #[test]
+            fn nested_test_2() {}
+        }
+
+        mod nested_tests_3 {}
+    }
+
+    mod nested_tests_4 {}
+}
+"#,
+            &[&TEST, &TEST, &TEST, &TEST, &TEST, &TEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 22..323,
+                            focus_range: Some(
+                                26..40,
+                            ),
+                            name: "nested_tests_0",
+                            kind: MODULE,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "root_tests::nested_tests_0",
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 51..192,
+                            focus_range: Some(
+                                55..69,
+                            ),
+                            name: "nested_tests_1",
+                            kind: MODULE,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "root_tests::nested_tests_0::nested_tests_1",
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 84..126,
+                            focus_range: Some(
+                                107..121,
+                            ),
+                            name: "nested_test_11",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "root_tests::nested_tests_0::nested_tests_1::nested_test_11",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 140..182,
+                            focus_range: Some(
+                                163..177,
+                            ),
+                            name: "nested_test_12",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "root_tests::nested_tests_0::nested_tests_1::nested_test_12",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 202..286,
+                            focus_range: Some(
+                                206..220,
+                            ),
+                            name: "nested_tests_2",
+                            kind: MODULE,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: TestMod {
+                            path: "root_tests::nested_tests_0::nested_tests_2",
+                        },
+                        cfg_exprs: [],
+                    },
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 235..276,
+                            focus_range: Some(
+                                258..271,
+                            ),
+                            name: "nested_test_2",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "root_tests::nested_tests_0::nested_tests_2::nested_test_2",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_with_feature() {
+        check(
+            r#"
+//- /lib.rs crate:foo cfg:feature=foo
+<|>
+#[test]
+#[cfg(feature = "foo")]
+fn test_foo1() {}
+"#,
+            &[&TEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..50,
+                            focus_range: Some(
+                                36..45,
+                            ),
+                            name: "test_foo1",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "test_foo1",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [
+                            KeyValue {
+                                key: "feature",
+                                value: "foo",
+                            },
+                        ],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_with_features() {
+        check(
+            r#"
+//- /lib.rs crate:foo cfg:feature=foo,feature=bar
+<|>
+#[test]
+#[cfg(all(feature = "foo", feature = "bar"))]
+fn test_foo1() {}
+"#,
+            &[&TEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                1,
+                            ),
+                            full_range: 1..72,
+                            focus_range: Some(
+                                58..67,
+                            ),
+                            name: "test_foo1",
+                            kind: FN,
+                            container_name: None,
+                            description: None,
+                            docs: None,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "test_foo1",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg_exprs: [
+                            All(
+                                [
+                                    KeyValue {
+                                        key: "feature",
+                                        value: "foo",
+                                    },
+                                    KeyValue {
+                                        key: "feature",
+                                        value: "bar",
+                                    },
+                                ],
+                            ),
+                        ],
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_runnables_no_test_function_in_module() {
+        check(
+            r#"
+//- /lib.rs
+<|>
+mod test_mod {
+    fn foo1() {}
+}
+"#,
+            &[],
+            expect![[r#"
+                []
+            "#]],
+        );
+    }
+}
diff --git a/crates/ide/src/status.rs b/crates/ide/src/status.rs
new file mode 100644
index 000000000..c23708181
--- /dev/null
+++ b/crates/ide/src/status.rs
@@ -0,0 +1,145 @@
+use std::{fmt, iter::FromIterator, sync::Arc};
+
+use base_db::{
+    salsa::debug::{DebugQueryTable, TableEntry},
+    FileTextQuery, SourceRootId,
+};
+use hir::MacroFile;
+use ide_db::{
+    symbol_index::{LibrarySymbolsQuery, SymbolIndex},
+    RootDatabase,
+};
+use profile::{memory_usage, Bytes};
+use rustc_hash::FxHashMap;
+use syntax::{ast, Parse, SyntaxNode};
+
+use crate::FileId;
+
+fn syntax_tree_stats(db: &RootDatabase) -> SyntaxTreeStats {
+    base_db::ParseQuery.in_db(db).entries::<SyntaxTreeStats>()
+}
+fn macro_syntax_tree_stats(db: &RootDatabase) -> SyntaxTreeStats {
+    hir::db::ParseMacroQuery.in_db(db).entries::<SyntaxTreeStats>()
+}
+
+// Feature: Status
+//
+// Shows internal statistic about memory usage of rust-analyzer.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Status**
+// |===
+pub(crate) fn status(db: &RootDatabase) -> String {
+    let files_stats = FileTextQuery.in_db(db).entries::<FilesStats>();
+    let syntax_tree_stats = syntax_tree_stats(db);
+    let macro_syntax_tree_stats = macro_syntax_tree_stats(db);
+    let symbols_stats = LibrarySymbolsQuery.in_db(db).entries::<LibrarySymbolsStats>();
+    format!(
+        "{}\n{}\n{}\n{} (macros)\n\n\nmemory:\n{}\ngc {:?} seconds ago",
+        files_stats,
+        symbols_stats,
+        syntax_tree_stats,
+        macro_syntax_tree_stats,
+        memory_usage(),
+        db.last_gc.elapsed().as_secs(),
+    )
+}
+
+#[derive(Default)]
+struct FilesStats {
+    total: usize,
+    size: Bytes,
+}
+
+impl fmt::Display for FilesStats {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{} ({}) files", self.total, self.size)
+    }
+}
+
+impl FromIterator<TableEntry<FileId, Arc<String>>> for FilesStats {
+    fn from_iter<T>(iter: T) -> FilesStats
+    where
+        T: IntoIterator<Item = TableEntry<FileId, Arc<String>>>,
+    {
+        let mut res = FilesStats::default();
+        for entry in iter {
+            res.total += 1;
+            res.size += entry.value.unwrap().len();
+        }
+        res
+    }
+}
+
+#[derive(Default)]
+pub(crate) struct SyntaxTreeStats {
+    total: usize,
+    pub(crate) retained: usize,
+}
+
+impl fmt::Display for SyntaxTreeStats {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{} trees, {} retained", self.total, self.retained)
+    }
+}
+
+impl FromIterator<TableEntry<FileId, Parse<ast::SourceFile>>> for SyntaxTreeStats {
+    fn from_iter<T>(iter: T) -> SyntaxTreeStats
+    where
+        T: IntoIterator<Item = TableEntry<FileId, Parse<ast::SourceFile>>>,
+    {
+        let mut res = SyntaxTreeStats::default();
+        for entry in iter {
+            res.total += 1;
+            res.retained += entry.value.is_some() as usize;
+        }
+        res
+    }
+}
+
+impl<M> FromIterator<TableEntry<MacroFile, Option<(Parse<SyntaxNode>, M)>>> for SyntaxTreeStats {
+    fn from_iter<T>(iter: T) -> SyntaxTreeStats
+    where
+        T: IntoIterator<Item = TableEntry<MacroFile, Option<(Parse<SyntaxNode>, M)>>>,
+    {
+        let mut res = SyntaxTreeStats::default();
+        for entry in iter {
+            res.total += 1;
+            res.retained += entry.value.is_some() as usize;
+        }
+        res
+    }
+}
+
+#[derive(Default)]
+struct LibrarySymbolsStats {
+    total: usize,
+    size: Bytes,
+}
+
+impl fmt::Display for LibrarySymbolsStats {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{} ({}) symbols", self.total, self.size)
+    }
+}
+
+impl FromIterator<TableEntry<(), Arc<FxHashMap<SourceRootId, SymbolIndex>>>>
+    for LibrarySymbolsStats
+{
+    fn from_iter<T>(iter: T) -> LibrarySymbolsStats
+    where
+        T: IntoIterator<Item = TableEntry<(), Arc<FxHashMap<SourceRootId, SymbolIndex>>>>,
+    {
+        let mut res = LibrarySymbolsStats::default();
+        for entry in iter {
+            let value = entry.value.unwrap();
+            for symbols in value.values() {
+                res.total += symbols.len();
+                res.size += symbols.memory_size();
+            }
+        }
+        res
+    }
+}
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
new file mode 100644
index 000000000..25d6f7abd
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -0,0 +1,879 @@
+mod tags;
+mod html;
+mod injection;
+#[cfg(test)]
+mod tests;
+
+use hir::{Name, Semantics, VariantDef};
+use ide_db::{
+    defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
+    RootDatabase,
+};
+use rustc_hash::FxHashMap;
+use syntax::{
+    ast::{self, HasFormatSpecifier},
+    AstNode, AstToken, Direction, NodeOrToken, SyntaxElement,
+    SyntaxKind::*,
+    TextRange, WalkEvent, T,
+};
+
+use crate::FileId;
+
+use ast::FormatSpecifier;
+pub(crate) use html::highlight_as_html;
+pub use tags::{Highlight, HighlightModifier, HighlightModifiers, HighlightTag};
+
+#[derive(Debug, Clone)]
+pub struct HighlightedRange {
+    pub range: TextRange,
+    pub highlight: Highlight,
+    pub binding_hash: Option<u64>,
+}
+
+// Feature: Semantic Syntax Highlighting
+//
+// rust-analyzer highlights the code semantically.
+// For example, `bar` in `foo::Bar` might be colored differently depending on whether `Bar` is an enum or a trait.
+// rust-analyzer does not specify colors directly, instead it assigns tag (like `struct`) and a set of modifiers (like `declaration`) to each token.
+// It's up to the client to map those to specific colors.
+//
+// The general rule is that a reference to an entity gets colored the same way as the entity itself.
+// We also give special modifier for `mut` and `&mut` local variables.
+pub(crate) fn highlight(
+    db: &RootDatabase,
+    file_id: FileId,
+    range_to_highlight: Option<TextRange>,
+    syntactic_name_ref_highlighting: bool,
+) -> Vec<HighlightedRange> {
+    let _p = profile::span("highlight");
+    let sema = Semantics::new(db);
+
+    // Determine the root based on the given range.
+    let (root, range_to_highlight) = {
+        let source_file = sema.parse(file_id);
+        match range_to_highlight {
+            Some(range) => {
+                let node = match source_file.syntax().covering_element(range) {
+                    NodeOrToken::Node(it) => it,
+                    NodeOrToken::Token(it) => it.parent(),
+                };
+                (node, range)
+            }
+            None => (source_file.syntax().clone(), source_file.syntax().text_range()),
+        }
+    };
+
+    let mut bindings_shadow_count: FxHashMap<Name, u32> = FxHashMap::default();
+    // We use a stack for the DFS traversal below.
+    // When we leave a node, the we use it to flatten the highlighted ranges.
+    let mut stack = HighlightedRangeStack::new();
+
+    let mut current_macro_call: Option<ast::MacroCall> = None;
+    let mut format_string: Option<SyntaxElement> = None;
+
+    // Walk all nodes, keeping track of whether we are inside a macro or not.
+    // If in macro, expand it first and highlight the expanded code.
+    for event in root.preorder_with_tokens() {
+        match &event {
+            WalkEvent::Enter(_) => stack.push(),
+            WalkEvent::Leave(_) => stack.pop(),
+        };
+
+        let event_range = match &event {
+            WalkEvent::Enter(it) => it.text_range(),
+            WalkEvent::Leave(it) => it.text_range(),
+        };
+
+        // Element outside of the viewport, no need to highlight
+        if range_to_highlight.intersect(event_range).is_none() {
+            continue;
+        }
+
+        // Track "inside macro" state
+        match event.clone().map(|it| it.into_node().and_then(ast::MacroCall::cast)) {
+            WalkEvent::Enter(Some(mc)) => {
+                current_macro_call = Some(mc.clone());
+                if let Some(range) = macro_call_range(&mc) {
+                    stack.add(HighlightedRange {
+                        range,
+                        highlight: HighlightTag::Macro.into(),
+                        binding_hash: None,
+                    });
+                }
+                if let Some(name) = mc.is_macro_rules() {
+                    if let Some((highlight, binding_hash)) = highlight_element(
+                        &sema,
+                        &mut bindings_shadow_count,
+                        syntactic_name_ref_highlighting,
+                        name.syntax().clone().into(),
+                    ) {
+                        stack.add(HighlightedRange {
+                            range: name.syntax().text_range(),
+                            highlight,
+                            binding_hash,
+                        });
+                    }
+                }
+                continue;
+            }
+            WalkEvent::Leave(Some(mc)) => {
+                assert!(current_macro_call == Some(mc));
+                current_macro_call = None;
+                format_string = None;
+            }
+            _ => (),
+        }
+
+        // Check for Rust code in documentation
+        match &event {
+            WalkEvent::Leave(NodeOrToken::Node(node)) => {
+                if let Some((doctest, range_mapping, new_comments)) =
+                    injection::extract_doc_comments(node)
+                {
+                    injection::highlight_doc_comment(
+                        doctest,
+                        range_mapping,
+                        new_comments,
+                        &mut stack,
+                    );
+                }
+            }
+            _ => (),
+        }
+
+        let element = match event {
+            WalkEvent::Enter(it) => it,
+            WalkEvent::Leave(_) => continue,
+        };
+
+        let range = element.text_range();
+
+        let element_to_highlight = if current_macro_call.is_some() && element.kind() != COMMENT {
+            // Inside a macro -- expand it first
+            let token = match element.clone().into_token() {
+                Some(it) if it.parent().kind() == TOKEN_TREE => it,
+                _ => continue,
+            };
+            let token = sema.descend_into_macros(token.clone());
+            let parent = token.parent();
+
+            // Check if macro takes a format string and remember it for highlighting later.
+            // The macros that accept a format string expand to a compiler builtin macros
+            // `format_args` and `format_args_nl`.
+            if let Some(name) = parent
+                .parent()
+                .and_then(ast::MacroCall::cast)
+                .and_then(|mc| mc.path())
+                .and_then(|p| p.segment())
+                .and_then(|s| s.name_ref())
+            {
+                match name.text().as_str() {
+                    "format_args" | "format_args_nl" => {
+                        format_string = parent
+                            .children_with_tokens()
+                            .filter(|t| t.kind() != WHITESPACE)
+                            .nth(1)
+                            .filter(|e| {
+                                ast::String::can_cast(e.kind())
+                                    || ast::RawString::can_cast(e.kind())
+                            })
+                    }
+                    _ => {}
+                }
+            }
+
+            // We only care Name and Name_ref
+            match (token.kind(), parent.kind()) {
+                (IDENT, NAME) | (IDENT, NAME_REF) => parent.into(),
+                _ => token.into(),
+            }
+        } else {
+            element.clone()
+        };
+
+        if let Some(token) = element.as_token().cloned().and_then(ast::RawString::cast) {
+            let expanded = element_to_highlight.as_token().unwrap().clone();
+            if injection::highlight_injection(&mut stack, &sema, token, expanded).is_some() {
+                continue;
+            }
+        }
+
+        let is_format_string = format_string.as_ref() == Some(&element_to_highlight);
+
+        if let Some((highlight, binding_hash)) = highlight_element(
+            &sema,
+            &mut bindings_shadow_count,
+            syntactic_name_ref_highlighting,
+            element_to_highlight.clone(),
+        ) {
+            stack.add(HighlightedRange { range, highlight, binding_hash });
+            if let Some(string) =
+                element_to_highlight.as_token().cloned().and_then(ast::String::cast)
+            {
+                if is_format_string {
+                    stack.push();
+                    string.lex_format_specifier(|piece_range, kind| {
+                        if let Some(highlight) = highlight_format_specifier(kind) {
+                            stack.add(HighlightedRange {
+                                range: piece_range + range.start(),
+                                highlight: highlight.into(),
+                                binding_hash: None,
+                            });
+                        }
+                    });
+                    stack.pop();
+                }
+                // Highlight escape sequences
+                if let Some(char_ranges) = string.char_ranges() {
+                    stack.push();
+                    for (piece_range, _) in char_ranges.iter().filter(|(_, char)| char.is_ok()) {
+                        if string.text()[piece_range.start().into()..].starts_with('\\') {
+                            stack.add(HighlightedRange {
+                                range: piece_range + range.start(),
+                                highlight: HighlightTag::EscapeSequence.into(),
+                                binding_hash: None,
+                            });
+                        }
+                    }
+                    stack.pop_and_inject(None);
+                }
+            } else if let Some(string) =
+                element_to_highlight.as_token().cloned().and_then(ast::RawString::cast)
+            {
+                if is_format_string {
+                    stack.push();
+                    string.lex_format_specifier(|piece_range, kind| {
+                        if let Some(highlight) = highlight_format_specifier(kind) {
+                            stack.add(HighlightedRange {
+                                range: piece_range + range.start(),
+                                highlight: highlight.into(),
+                                binding_hash: None,
+                            });
+                        }
+                    });
+                    stack.pop();
+                }
+            }
+        }
+    }
+
+    stack.flattened()
+}
+
+#[derive(Debug)]
+struct HighlightedRangeStack {
+    stack: Vec<Vec<HighlightedRange>>,
+}
+
+/// We use a stack to implement the flattening logic for the highlighted
+/// syntax ranges.
+impl HighlightedRangeStack {
+    fn new() -> Self {
+        Self { stack: vec![Vec::new()] }
+    }
+
+    fn push(&mut self) {
+        self.stack.push(Vec::new());
+    }
+
+    /// Flattens the highlighted ranges.
+    ///
+    /// For example `#[cfg(feature = "foo")]` contains the nested ranges:
+    /// 1) parent-range: Attribute [0, 23)
+    /// 2) child-range: String [16, 21)
+    ///
+    /// The following code implements the flattening, for our example this results to:
+    /// `[Attribute [0, 16), String [16, 21), Attribute [21, 23)]`
+    fn pop(&mut self) {
+        let children = self.stack.pop().unwrap();
+        let prev = self.stack.last_mut().unwrap();
+        let needs_flattening = !children.is_empty()
+            && !prev.is_empty()
+            && prev.last().unwrap().range.contains_range(children.first().unwrap().range);
+        if !needs_flattening {
+            prev.extend(children);
+        } else {
+            let mut parent = prev.pop().unwrap();
+            for ele in children {
+                assert!(parent.range.contains_range(ele.range));
+
+                let cloned = Self::intersect(&mut parent, &ele);
+                if !parent.range.is_empty() {
+                    prev.push(parent);
+                }
+                prev.push(ele);
+                parent = cloned;
+            }
+            if !parent.range.is_empty() {
+                prev.push(parent);
+            }
+        }
+    }
+
+    /// Intersects the `HighlightedRange` `parent` with `child`.
+    /// `parent` is mutated in place, becoming the range before `child`.
+    /// Returns the range (of the same type as `parent`) *after* `child`.
+    fn intersect(parent: &mut HighlightedRange, child: &HighlightedRange) -> HighlightedRange {
+        assert!(parent.range.contains_range(child.range));
+
+        let mut cloned = parent.clone();
+        parent.range = TextRange::new(parent.range.start(), child.range.start());
+        cloned.range = TextRange::new(child.range.end(), cloned.range.end());
+
+        cloned
+    }
+
+    /// Remove the `HighlightRange` of `parent` that's currently covered by `child`.
+    fn intersect_partial(parent: &mut HighlightedRange, child: &HighlightedRange) {
+        assert!(
+            parent.range.start() <= child.range.start()
+                && parent.range.end() >= child.range.start()
+                && child.range.end() > parent.range.end()
+        );
+
+        parent.range = TextRange::new(parent.range.start(), child.range.start());
+    }
+
+    /// Similar to `pop`, but can modify arbitrary prior ranges (where `pop`)
+    /// can only modify the last range currently on the stack.
+    /// Can be used to do injections that span multiple ranges, like the
+    /// doctest injection below.
+    /// If `overwrite_parent` is non-optional, the highlighting of the parent range
+    /// is overwritten with the argument.
+    ///
+    /// Note that `pop` can be simulated by `pop_and_inject(false)` but the
+    /// latter is computationally more expensive.
+    fn pop_and_inject(&mut self, overwrite_parent: Option<Highlight>) {
+        let mut children = self.stack.pop().unwrap();
+        let prev = self.stack.last_mut().unwrap();
+        children.sort_by_key(|range| range.range.start());
+        prev.sort_by_key(|range| range.range.start());
+
+        for child in children {
+            if let Some(idx) =
+                prev.iter().position(|parent| parent.range.contains_range(child.range))
+            {
+                if let Some(tag) = overwrite_parent {
+                    prev[idx].highlight = tag;
+                }
+
+                let cloned = Self::intersect(&mut prev[idx], &child);
+                let insert_idx = if prev[idx].range.is_empty() {
+                    prev.remove(idx);
+                    idx
+                } else {
+                    idx + 1
+                };
+                prev.insert(insert_idx, child);
+                if !cloned.range.is_empty() {
+                    prev.insert(insert_idx + 1, cloned);
+                }
+            } else {
+                let maybe_idx =
+                    prev.iter().position(|parent| parent.range.contains(child.range.start()));
+                match (overwrite_parent, maybe_idx) {
+                    (Some(_), Some(idx)) => {
+                        Self::intersect_partial(&mut prev[idx], &child);
+                        let insert_idx = if prev[idx].range.is_empty() {
+                            prev.remove(idx);
+                            idx
+                        } else {
+                            idx + 1
+                        };
+                        prev.insert(insert_idx, child);
+                    }
+                    (_, None) => {
+                        let idx = prev
+                            .binary_search_by_key(&child.range.start(), |range| range.range.start())
+                            .unwrap_or_else(|x| x);
+                        prev.insert(idx, child);
+                    }
+                    _ => {
+                        unreachable!("child range should be completely contained in parent range");
+                    }
+                }
+            }
+        }
+    }
+
+    fn add(&mut self, range: HighlightedRange) {
+        self.stack
+            .last_mut()
+            .expect("during DFS traversal, the stack must not be empty")
+            .push(range)
+    }
+
+    fn flattened(mut self) -> Vec<HighlightedRange> {
+        assert_eq!(
+            self.stack.len(),
+            1,
+            "after DFS traversal, the stack should only contain a single element"
+        );
+        let mut res = self.stack.pop().unwrap();
+        res.sort_by_key(|range| range.range.start());
+        // Check that ranges are sorted and disjoint
+        assert!(res
+            .iter()
+            .zip(res.iter().skip(1))
+            .all(|(left, right)| left.range.end() <= right.range.start()));
+        res
+    }
+}
+
+fn highlight_format_specifier(kind: FormatSpecifier) -> Option<HighlightTag> {
+    Some(match kind {
+        FormatSpecifier::Open
+        | FormatSpecifier::Close
+        | FormatSpecifier::Colon
+        | FormatSpecifier::Fill
+        | FormatSpecifier::Align
+        | FormatSpecifier::Sign
+        | FormatSpecifier::NumberSign
+        | FormatSpecifier::DollarSign
+        | FormatSpecifier::Dot
+        | FormatSpecifier::Asterisk
+        | FormatSpecifier::QuestionMark => HighlightTag::FormatSpecifier,
+        FormatSpecifier::Integer | FormatSpecifier::Zero => HighlightTag::NumericLiteral,
+        FormatSpecifier::Identifier => HighlightTag::Local,
+    })
+}
+
+fn macro_call_range(macro_call: &ast::MacroCall) -> Option<TextRange> {
+    let path = macro_call.path()?;
+    let name_ref = path.segment()?.name_ref()?;
+
+    let range_start = name_ref.syntax().text_range().start();
+    let mut range_end = name_ref.syntax().text_range().end();
+    for sibling in path.syntax().siblings_with_tokens(Direction::Next) {
+        match sibling.kind() {
+            T![!] | IDENT => range_end = sibling.text_range().end(),
+            _ => (),
+        }
+    }
+
+    Some(TextRange::new(range_start, range_end))
+}
+
+fn highlight_element(
+    sema: &Semantics<RootDatabase>,
+    bindings_shadow_count: &mut FxHashMap<Name, u32>,
+    syntactic_name_ref_highlighting: bool,
+    element: SyntaxElement,
+) -> Option<(Highlight, Option<u64>)> {
+    let db = sema.db;
+    let mut binding_hash = None;
+    let highlight: Highlight = match element.kind() {
+        FN => {
+            bindings_shadow_count.clear();
+            return None;
+        }
+
+        // Highlight definitions depending on the "type" of the definition.
+        NAME => {
+            let name = element.into_node().and_then(ast::Name::cast).unwrap();
+            let name_kind = classify_name(sema, &name);
+
+            if let Some(NameClass::Definition(Definition::Local(local))) = &name_kind {
+                if let Some(name) = local.name(db) {
+                    let shadow_count = bindings_shadow_count.entry(name.clone()).or_default();
+                    *shadow_count += 1;
+                    binding_hash = Some(calc_binding_hash(&name, *shadow_count))
+                }
+            };
+
+            match name_kind {
+                Some(NameClass::ExternCrate(_)) => HighlightTag::Module.into(),
+                Some(NameClass::Definition(def)) => {
+                    highlight_def(db, def) | HighlightModifier::Definition
+                }
+                Some(NameClass::ConstReference(def)) => highlight_def(db, def),
+                Some(NameClass::FieldShorthand { field, .. }) => {
+                    let mut h = HighlightTag::Field.into();
+                    if let Definition::Field(field) = field {
+                        if let VariantDef::Union(_) = field.parent_def(db) {
+                            h |= HighlightModifier::Unsafe;
+                        }
+                    }
+
+                    h
+                }
+                None => highlight_name_by_syntax(name) | HighlightModifier::Definition,
+            }
+        }
+
+        // Highlight references like the definitions they resolve to
+        NAME_REF if element.ancestors().any(|it| it.kind() == ATTR) => {
+            Highlight::from(HighlightTag::Function) | HighlightModifier::Attribute
+        }
+        NAME_REF => {
+            let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
+            highlight_func_by_name_ref(sema, &name_ref).unwrap_or_else(|| {
+                match classify_name_ref(sema, &name_ref) {
+                    Some(name_kind) => match name_kind {
+                        NameRefClass::ExternCrate(_) => HighlightTag::Module.into(),
+                        NameRefClass::Definition(def) => {
+                            if let Definition::Local(local) = &def {
+                                if let Some(name) = local.name(db) {
+                                    let shadow_count =
+                                        bindings_shadow_count.entry(name.clone()).or_default();
+                                    binding_hash = Some(calc_binding_hash(&name, *shadow_count))
+                                }
+                            };
+
+                            let mut h = highlight_def(db, def);
+
+                            if let Some(parent) = name_ref.syntax().parent() {
+                                if matches!(parent.kind(), FIELD_EXPR | RECORD_PAT_FIELD) {
+                                    if let Definition::Field(field) = def {
+                                        if let VariantDef::Union(_) = field.parent_def(db) {
+                                            h |= HighlightModifier::Unsafe;
+                                        }
+                                    }
+                                }
+                            }
+
+                            h
+                        }
+                        NameRefClass::FieldShorthand { .. } => HighlightTag::Field.into(),
+                    },
+                    None if syntactic_name_ref_highlighting => {
+                        highlight_name_ref_by_syntax(name_ref, sema)
+                    }
+                    None => HighlightTag::UnresolvedReference.into(),
+                }
+            })
+        }
+
+        // Simple token-based highlighting
+        COMMENT => {
+            let comment = element.into_token().and_then(ast::Comment::cast)?;
+            let h = HighlightTag::Comment;
+            match comment.kind().doc {
+                Some(_) => h | HighlightModifier::Documentation,
+                None => h.into(),
+            }
+        }
+        STRING | RAW_STRING | RAW_BYTE_STRING | BYTE_STRING => HighlightTag::StringLiteral.into(),
+        ATTR => HighlightTag::Attribute.into(),
+        INT_NUMBER | FLOAT_NUMBER => HighlightTag::NumericLiteral.into(),
+        BYTE => HighlightTag::ByteLiteral.into(),
+        CHAR => HighlightTag::CharLiteral.into(),
+        QUESTION => Highlight::new(HighlightTag::Operator) | HighlightModifier::ControlFlow,
+        LIFETIME => {
+            let h = Highlight::new(HighlightTag::Lifetime);
+            match element.parent().map(|it| it.kind()) {
+                Some(LIFETIME_PARAM) | Some(LABEL) => h | HighlightModifier::Definition,
+                _ => h,
+            }
+        }
+        p if p.is_punct() => match p {
+            T![&] => {
+                let h = HighlightTag::Operator.into();
+                let is_unsafe = element
+                    .parent()
+                    .and_then(ast::RefExpr::cast)
+                    .map(|ref_expr| sema.is_unsafe_ref_expr(&ref_expr))
+                    .unwrap_or(false);
+                if is_unsafe {
+                    h | HighlightModifier::Unsafe
+                } else {
+                    h
+                }
+            }
+            T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] => HighlightTag::Operator.into(),
+            T![!] if element.parent().and_then(ast::MacroCall::cast).is_some() => {
+                HighlightTag::Macro.into()
+            }
+            T![*] if element.parent().and_then(ast::PtrType::cast).is_some() => {
+                HighlightTag::Keyword.into()
+            }
+            T![*] if element.parent().and_then(ast::PrefixExpr::cast).is_some() => {
+                let prefix_expr = element.parent().and_then(ast::PrefixExpr::cast)?;
+
+                let expr = prefix_expr.expr()?;
+                let ty = sema.type_of_expr(&expr)?;
+                if ty.is_raw_ptr() {
+                    HighlightTag::Operator | HighlightModifier::Unsafe
+                } else if let Some(ast::PrefixOp::Deref) = prefix_expr.op_kind() {
+                    HighlightTag::Operator.into()
+                } else {
+                    HighlightTag::Punctuation.into()
+                }
+            }
+            T![-] if element.parent().and_then(ast::PrefixExpr::cast).is_some() => {
+                HighlightTag::NumericLiteral.into()
+            }
+            _ if element.parent().and_then(ast::PrefixExpr::cast).is_some() => {
+                HighlightTag::Operator.into()
+            }
+            _ if element.parent().and_then(ast::BinExpr::cast).is_some() => {
+                HighlightTag::Operator.into()
+            }
+            _ if element.parent().and_then(ast::RangeExpr::cast).is_some() => {
+                HighlightTag::Operator.into()
+            }
+            _ if element.parent().and_then(ast::RangePat::cast).is_some() => {
+                HighlightTag::Operator.into()
+            }
+            _ if element.parent().and_then(ast::RestPat::cast).is_some() => {
+                HighlightTag::Operator.into()
+            }
+            _ if element.parent().and_then(ast::Attr::cast).is_some() => {
+                HighlightTag::Attribute.into()
+            }
+            _ => HighlightTag::Punctuation.into(),
+        },
+
+        k if k.is_keyword() => {
+            let h = Highlight::new(HighlightTag::Keyword);
+            match k {
+                T![break]
+                | T![continue]
+                | T![else]
+                | T![if]
+                | T![loop]
+                | T![match]
+                | T![return]
+                | T![while]
+                | T![in] => h | HighlightModifier::ControlFlow,
+                T![for] if !is_child_of_impl(&element) => h | HighlightModifier::ControlFlow,
+                T![unsafe] => h | HighlightModifier::Unsafe,
+                T![true] | T![false] => HighlightTag::BoolLiteral.into(),
+                T![self] => {
+                    let self_param_is_mut = element
+                        .parent()
+                        .and_then(ast::SelfParam::cast)
+                        .and_then(|p| p.mut_token())
+                        .is_some();
+                    // closure to enforce lazyness
+                    let self_path = || {
+                        sema.resolve_path(&element.parent()?.parent().and_then(ast::Path::cast)?)
+                    };
+                    if self_param_is_mut
+                        || matches!(self_path(),
+                            Some(hir::PathResolution::Local(local))
+                                if local.is_self(db)
+                                    && (local.is_mut(db) || local.ty(db).is_mutable_reference())
+                        )
+                    {
+                        HighlightTag::SelfKeyword | HighlightModifier::Mutable
+                    } else {
+                        HighlightTag::SelfKeyword.into()
+                    }
+                }
+                T![ref] => element
+                    .parent()
+                    .and_then(ast::IdentPat::cast)
+                    .and_then(|ident_pat| {
+                        if sema.is_unsafe_ident_pat(&ident_pat) {
+                            Some(HighlightModifier::Unsafe)
+                        } else {
+                            None
+                        }
+                    })
+                    .map(|modifier| h | modifier)
+                    .unwrap_or(h),
+                _ => h,
+            }
+        }
+
+        _ => return None,
+    };
+
+    return Some((highlight, binding_hash));
+
+    fn calc_binding_hash(name: &Name, shadow_count: u32) -> u64 {
+        fn hash<T: std::hash::Hash + std::fmt::Debug>(x: T) -> u64 {
+            use std::{collections::hash_map::DefaultHasher, hash::Hasher};
+
+            let mut hasher = DefaultHasher::new();
+            x.hash(&mut hasher);
+            hasher.finish()
+        }
+
+        hash((name, shadow_count))
+    }
+}
+
+fn is_child_of_impl(element: &SyntaxElement) -> bool {
+    match element.parent() {
+        Some(e) => e.kind() == IMPL,
+        _ => false,
+    }
+}
+
+fn highlight_func_by_name_ref(
+    sema: &Semantics<RootDatabase>,
+    name_ref: &ast::NameRef,
+) -> Option<Highlight> {
+    let method_call = name_ref.syntax().parent().and_then(ast::MethodCallExpr::cast)?;
+    highlight_method_call(sema, &method_call)
+}
+
+fn highlight_method_call(
+    sema: &Semantics<RootDatabase>,
+    method_call: &ast::MethodCallExpr,
+) -> Option<Highlight> {
+    let func = sema.resolve_method_call(&method_call)?;
+    let mut h = HighlightTag::Function.into();
+    if func.is_unsafe(sema.db) || sema.is_unsafe_method_call(&method_call) {
+        h |= HighlightModifier::Unsafe;
+    }
+    if let Some(self_param) = func.self_param(sema.db) {
+        match self_param.access(sema.db) {
+            hir::Access::Shared => (),
+            hir::Access::Exclusive => h |= HighlightModifier::Mutable,
+            hir::Access::Owned => {
+                if let Some(receiver_ty) =
+                    method_call.receiver().and_then(|it| sema.type_of_expr(&it))
+                {
+                    if !receiver_ty.is_copy(sema.db) {
+                        h |= HighlightModifier::Consuming
+                    }
+                }
+            }
+        }
+    }
+    Some(h)
+}
+
+fn highlight_def(db: &RootDatabase, def: Definition) -> Highlight {
+    match def {
+        Definition::Macro(_) => HighlightTag::Macro,
+        Definition::Field(_) => HighlightTag::Field,
+        Definition::ModuleDef(def) => match def {
+            hir::ModuleDef::Module(_) => HighlightTag::Module,
+            hir::ModuleDef::Function(func) => {
+                let mut h = HighlightTag::Function.into();
+                if func.is_unsafe(db) {
+                    h |= HighlightModifier::Unsafe;
+                }
+                return h;
+            }
+            hir::ModuleDef::Adt(hir::Adt::Struct(_)) => HighlightTag::Struct,
+            hir::ModuleDef::Adt(hir::Adt::Enum(_)) => HighlightTag::Enum,
+            hir::ModuleDef::Adt(hir::Adt::Union(_)) => HighlightTag::Union,
+            hir::ModuleDef::EnumVariant(_) => HighlightTag::EnumVariant,
+            hir::ModuleDef::Const(_) => HighlightTag::Constant,
+            hir::ModuleDef::Trait(_) => HighlightTag::Trait,
+            hir::ModuleDef::TypeAlias(_) => HighlightTag::TypeAlias,
+            hir::ModuleDef::BuiltinType(_) => HighlightTag::BuiltinType,
+            hir::ModuleDef::Static(s) => {
+                let mut h = Highlight::new(HighlightTag::Static);
+                if s.is_mut(db) {
+                    h |= HighlightModifier::Mutable;
+                    h |= HighlightModifier::Unsafe;
+                }
+                return h;
+            }
+        },
+        Definition::SelfType(_) => HighlightTag::SelfType,
+        Definition::TypeParam(_) => HighlightTag::TypeParam,
+        Definition::Local(local) => {
+            let tag =
+                if local.is_param(db) { HighlightTag::ValueParam } else { HighlightTag::Local };
+            let mut h = Highlight::new(tag);
+            if local.is_mut(db) || local.ty(db).is_mutable_reference() {
+                h |= HighlightModifier::Mutable;
+            }
+            return h;
+        }
+    }
+    .into()
+}
+
+fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
+    let default = HighlightTag::UnresolvedReference;
+
+    let parent = match name.syntax().parent() {
+        Some(it) => it,
+        _ => return default.into(),
+    };
+
+    let tag = match parent.kind() {
+        STRUCT => HighlightTag::Struct,
+        ENUM => HighlightTag::Enum,
+        UNION => HighlightTag::Union,
+        TRAIT => HighlightTag::Trait,
+        TYPE_ALIAS => HighlightTag::TypeAlias,
+        TYPE_PARAM => HighlightTag::TypeParam,
+        RECORD_FIELD => HighlightTag::Field,
+        MODULE => HighlightTag::Module,
+        FN => HighlightTag::Function,
+        CONST => HighlightTag::Constant,
+        STATIC => HighlightTag::Static,
+        VARIANT => HighlightTag::EnumVariant,
+        IDENT_PAT => HighlightTag::Local,
+        _ => default,
+    };
+
+    tag.into()
+}
+
+fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabase>) -> Highlight {
+    let default = HighlightTag::UnresolvedReference;
+
+    let parent = match name.syntax().parent() {
+        Some(it) => it,
+        _ => return default.into(),
+    };
+
+    match parent.kind() {
+        METHOD_CALL_EXPR => {
+            return ast::MethodCallExpr::cast(parent)
+                .and_then(|method_call| highlight_method_call(sema, &method_call))
+                .unwrap_or_else(|| HighlightTag::Function.into());
+        }
+        FIELD_EXPR => {
+            let h = HighlightTag::Field;
+            let is_union = ast::FieldExpr::cast(parent)
+                .and_then(|field_expr| {
+                    let field = sema.resolve_field(&field_expr)?;
+                    Some(if let VariantDef::Union(_) = field.parent_def(sema.db) {
+                        true
+                    } else {
+                        false
+                    })
+                })
+                .unwrap_or(false);
+            if is_union {
+                h | HighlightModifier::Unsafe
+            } else {
+                h.into()
+            }
+        }
+        PATH_SEGMENT => {
+            let path = match parent.parent().and_then(ast::Path::cast) {
+                Some(it) => it,
+                _ => return default.into(),
+            };
+            let expr = match path.syntax().parent().and_then(ast::PathExpr::cast) {
+                Some(it) => it,
+                _ => {
+                    // within path, decide whether it is module or adt by checking for uppercase name
+                    return if name.text().chars().next().unwrap_or_default().is_uppercase() {
+                        HighlightTag::Struct
+                    } else {
+                        HighlightTag::Module
+                    }
+                    .into();
+                }
+            };
+            let parent = match expr.syntax().parent() {
+                Some(it) => it,
+                None => return default.into(),
+            };
+
+            match parent.kind() {
+                CALL_EXPR => HighlightTag::Function.into(),
+                _ => if name.text().chars().next().unwrap_or_default().is_uppercase() {
+                    HighlightTag::Struct.into()
+                } else {
+                    HighlightTag::Constant
+                }
+                .into(),
+            }
+        }
+        _ => default.into(),
+    }
+}
diff --git a/crates/ide/src/syntax_highlighting/html.rs b/crates/ide/src/syntax_highlighting/html.rs
new file mode 100644
index 000000000..249368ff8
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/html.rs
@@ -0,0 +1,97 @@
+//! Renders a bit of code as HTML.
+
+use base_db::SourceDatabase;
+use oorandom::Rand32;
+use syntax::{AstNode, TextRange, TextSize};
+
+use crate::{syntax_highlighting::highlight, FileId, RootDatabase};
+
+pub(crate) fn highlight_as_html(db: &RootDatabase, file_id: FileId, rainbow: bool) -> String {
+    let parse = db.parse(file_id);
+
+    fn rainbowify(seed: u64) -> String {
+        let mut rng = Rand32::new(seed);
+        format!(
+            "hsl({h},{s}%,{l}%)",
+            h = rng.rand_range(0..361),
+            s = rng.rand_range(42..99),
+            l = rng.rand_range(40..91),
+        )
+    }
+
+    let ranges = highlight(db, file_id, None, false);
+    let text = parse.tree().syntax().to_string();
+    let mut prev_pos = TextSize::from(0);
+    let mut buf = String::new();
+    buf.push_str(&STYLE);
+    buf.push_str("<pre><code>");
+    for range in &ranges {
+        if range.range.start() > prev_pos {
+            let curr = &text[TextRange::new(prev_pos, range.range.start())];
+            let text = html_escape(curr);
+            buf.push_str(&text);
+        }
+        let curr = &text[TextRange::new(range.range.start(), range.range.end())];
+
+        let class = range.highlight.to_string().replace('.', " ");
+        let color = match (rainbow, range.binding_hash) {
+            (true, Some(hash)) => {
+                format!(" data-binding-hash=\"{}\" style=\"color: {};\"", hash, rainbowify(hash))
+            }
+            _ => "".into(),
+        };
+        buf.push_str(&format!("<span class=\"{}\"{}>{}</span>", class, color, html_escape(curr)));
+
+        prev_pos = range.range.end();
+    }
+    // Add the remaining (non-highlighted) text
+    let curr = &text[TextRange::new(prev_pos, TextSize::of(&text))];
+    let text = html_escape(curr);
+    buf.push_str(&text);
+    buf.push_str("</code></pre>");
+    buf
+}
+
+//FIXME: like, real html escaping
+fn html_escape(text: &str) -> String {
+    text.replace("<", "&lt;").replace(">", "&gt;")
+}
+
+const STYLE: &str = "
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+";
diff --git a/crates/ide/src/syntax_highlighting/injection.rs b/crates/ide/src/syntax_highlighting/injection.rs
new file mode 100644
index 000000000..43f4e6fea
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/injection.rs
@@ -0,0 +1,187 @@
+//! Syntax highlighting injections such as highlighting of documentation tests.
+
+use std::{collections::BTreeMap, convert::TryFrom};
+
+use ast::{HasQuotes, HasStringValue};
+use hir::Semantics;
+use itertools::Itertools;
+use syntax::{ast, AstToken, SyntaxNode, SyntaxToken, TextRange, TextSize};
+
+use crate::{
+    call_info::ActiveParameter, Analysis, Highlight, HighlightModifier, HighlightTag,
+    HighlightedRange, RootDatabase,
+};
+
+use super::HighlightedRangeStack;
+
+pub(super) fn highlight_injection(
+    acc: &mut HighlightedRangeStack,
+    sema: &Semantics<RootDatabase>,
+    literal: ast::RawString,
+    expanded: SyntaxToken,
+) -> Option<()> {
+    let active_parameter = ActiveParameter::at_token(&sema, expanded)?;
+    if !active_parameter.name.starts_with("ra_fixture") {
+        return None;
+    }
+    let value = literal.value()?;
+    let (analysis, tmp_file_id) = Analysis::from_single_file(value.into_owned());
+
+    if let Some(range) = literal.open_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    for mut h in analysis.highlight(tmp_file_id).unwrap() {
+        if let Some(r) = literal.map_range_up(h.range) {
+            h.range = r;
+            acc.add(h)
+        }
+    }
+
+    if let Some(range) = literal.close_quote_text_range() {
+        acc.add(HighlightedRange {
+            range,
+            highlight: HighlightTag::StringLiteral.into(),
+            binding_hash: None,
+        })
+    }
+
+    Some(())
+}
+
+/// Mapping from extracted documentation code to original code
+type RangesMap = BTreeMap<TextSize, TextSize>;
+
+const RUSTDOC_FENCE: &'static str = "```";
+const RUSTDOC_FENCE_TOKENS: &[&'static str] =
+    &["", "rust", "should_panic", "ignore", "no_run", "compile_fail", "edition2015", "edition2018"];
+
+/// Extracts Rust code from documentation comments as well as a mapping from
+/// the extracted source code back to the original source ranges.
+/// Lastly, a vector of new comment highlight ranges (spanning only the
+/// comment prefix) is returned which is used in the syntax highlighting
+/// injection to replace the previous (line-spanning) comment ranges.
+pub(super) fn extract_doc_comments(
+    node: &SyntaxNode,
+) -> Option<(String, RangesMap, Vec<HighlightedRange>)> {
+    // wrap the doctest into function body to get correct syntax highlighting
+    let prefix = "fn doctest() {\n";
+    let suffix = "}\n";
+    // Mapping from extracted documentation code to original code
+    let mut range_mapping: RangesMap = BTreeMap::new();
+    let mut line_start = TextSize::try_from(prefix.len()).unwrap();
+    let mut is_codeblock = false;
+    let mut is_doctest = false;
+    // Replace the original, line-spanning comment ranges by new, only comment-prefix
+    // spanning comment ranges.
+    let mut new_comments = Vec::new();
+    let doctest = node
+        .children_with_tokens()
+        .filter_map(|el| el.into_token().and_then(ast::Comment::cast))
+        .filter(|comment| comment.kind().doc.is_some())
+        .filter(|comment| {
+            if let Some(idx) = comment.text().find(RUSTDOC_FENCE) {
+                is_codeblock = !is_codeblock;
+                // Check whether code is rust by inspecting fence guards
+                let guards = &comment.text()[idx + RUSTDOC_FENCE.len()..];
+                let is_rust =
+                    guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                is_doctest = is_codeblock && is_rust;
+                false
+            } else {
+                is_doctest
+            }
+        })
+        .map(|comment| {
+            let prefix_len = comment.prefix().len();
+            let line: &str = comment.text().as_str();
+            let range = comment.syntax().text_range();
+
+            // whitespace after comment is ignored
+            let pos = if let Some(ws) = line.chars().nth(prefix_len).filter(|c| c.is_whitespace()) {
+                prefix_len + ws.len_utf8()
+            } else {
+                prefix_len
+            };
+
+            // lines marked with `#` should be ignored in output, we skip the `#` char
+            let pos = if let Some(ws) = line.chars().nth(pos).filter(|&c| c == '#') {
+                pos + ws.len_utf8()
+            } else {
+                pos
+            };
+
+            range_mapping.insert(line_start, range.start() + TextSize::try_from(pos).unwrap());
+            new_comments.push(HighlightedRange {
+                range: TextRange::new(
+                    range.start(),
+                    range.start() + TextSize::try_from(pos).unwrap(),
+                ),
+                highlight: HighlightTag::Comment | HighlightModifier::Documentation,
+                binding_hash: None,
+            });
+            line_start += range.len() - TextSize::try_from(pos).unwrap();
+            line_start += TextSize::try_from('\n'.len_utf8()).unwrap();
+
+            line[pos..].to_owned()
+        })
+        .join("\n");
+
+    if doctest.is_empty() {
+        return None;
+    }
+
+    let doctest = format!("{}{}{}", prefix, doctest, suffix);
+    Some((doctest, range_mapping, new_comments))
+}
+
+/// Injection of syntax highlighting of doctests.
+pub(super) fn highlight_doc_comment(
+    text: String,
+    range_mapping: RangesMap,
+    new_comments: Vec<HighlightedRange>,
+    stack: &mut HighlightedRangeStack,
+) {
+    let (analysis, tmp_file_id) = Analysis::from_single_file(text);
+
+    stack.push();
+    for mut h in analysis.with_db(|db| super::highlight(db, tmp_file_id, None, true)).unwrap() {
+        // Determine start offset and end offset in case of multi-line ranges
+        let mut start_offset = None;
+        let mut end_offset = None;
+        for (line_start, orig_line_start) in range_mapping.range(..h.range.end()).rev() {
+            // It's possible for orig_line_start - line_start to be negative. Add h.range.start()
+            // here and remove it from the end range after the loop below so that the values are
+            // always non-negative.
+            let offset = h.range.start() + orig_line_start - line_start;
+            if line_start <= &h.range.start() {
+                start_offset.get_or_insert(offset);
+                break;
+            } else {
+                end_offset.get_or_insert(offset);
+            }
+        }
+        if let Some(start_offset) = start_offset {
+            h.range = TextRange::new(
+                start_offset,
+                h.range.end() + end_offset.unwrap_or(start_offset) - h.range.start(),
+            );
+
+            h.highlight |= HighlightModifier::Injected;
+            stack.add(h);
+        }
+    }
+
+    // Inject the comment prefix highlight ranges
+    stack.push();
+    for comment in new_comments {
+        stack.add(comment);
+    }
+    stack.pop_and_inject(None);
+    stack
+        .pop_and_inject(Some(Highlight::from(HighlightTag::Generic) | HighlightModifier::Injected));
+}
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
new file mode 100644
index 000000000..c1b817f06
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -0,0 +1,206 @@
+//! Defines token tags we use for syntax highlighting.
+//! A tag is not unlike a CSS class.
+
+use std::{fmt, ops};
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct Highlight {
+    pub tag: HighlightTag,
+    pub modifiers: HighlightModifiers,
+}
+
+#[derive(Default, Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub struct HighlightModifiers(u32);
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum HighlightTag {
+    Attribute,
+    BoolLiteral,
+    BuiltinType,
+    ByteLiteral,
+    CharLiteral,
+    Comment,
+    Constant,
+    Enum,
+    EnumVariant,
+    EscapeSequence,
+    Field,
+    Function,
+    Generic,
+    Keyword,
+    Lifetime,
+    Macro,
+    Module,
+    NumericLiteral,
+    Punctuation,
+    SelfKeyword,
+    SelfType,
+    Static,
+    StringLiteral,
+    Struct,
+    Trait,
+    TypeAlias,
+    TypeParam,
+    Union,
+    ValueParam,
+    Local,
+    UnresolvedReference,
+    FormatSpecifier,
+    Operator,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[repr(u8)]
+pub enum HighlightModifier {
+    /// Used to differentiate individual elements within attributes.
+    Attribute = 0,
+    /// Used with keywords like `if` and `break`.
+    ControlFlow,
+    /// `foo` in `fn foo(x: i32)` is a definition, `foo` in `foo(90 + 2)` is
+    /// not.
+    Definition,
+    Documentation,
+    Injected,
+    Mutable,
+    Consuming,
+    Unsafe,
+}
+
+impl HighlightTag {
+    fn as_str(self) -> &'static str {
+        match self {
+            HighlightTag::Attribute => "attribute",
+            HighlightTag::BoolLiteral => "bool_literal",
+            HighlightTag::BuiltinType => "builtin_type",
+            HighlightTag::ByteLiteral => "byte_literal",
+            HighlightTag::CharLiteral => "char_literal",
+            HighlightTag::Comment => "comment",
+            HighlightTag::Constant => "constant",
+            HighlightTag::Enum => "enum",
+            HighlightTag::EnumVariant => "enum_variant",
+            HighlightTag::EscapeSequence => "escape_sequence",
+            HighlightTag::Field => "field",
+            HighlightTag::FormatSpecifier => "format_specifier",
+            HighlightTag::Function => "function",
+            HighlightTag::Generic => "generic",
+            HighlightTag::Keyword => "keyword",
+            HighlightTag::Lifetime => "lifetime",
+            HighlightTag::Punctuation => "punctuation",
+            HighlightTag::Macro => "macro",
+            HighlightTag::Module => "module",
+            HighlightTag::NumericLiteral => "numeric_literal",
+            HighlightTag::Operator => "operator",
+            HighlightTag::SelfKeyword => "self_keyword",
+            HighlightTag::SelfType => "self_type",
+            HighlightTag::Static => "static",
+            HighlightTag::StringLiteral => "string_literal",
+            HighlightTag::Struct => "struct",
+            HighlightTag::Trait => "trait",
+            HighlightTag::TypeAlias => "type_alias",
+            HighlightTag::TypeParam => "type_param",
+            HighlightTag::Union => "union",
+            HighlightTag::ValueParam => "value_param",
+            HighlightTag::Local => "variable",
+            HighlightTag::UnresolvedReference => "unresolved_reference",
+        }
+    }
+}
+
+impl fmt::Display for HighlightTag {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_str(), f)
+    }
+}
+
+impl HighlightModifier {
+    const ALL: &'static [HighlightModifier] = &[
+        HighlightModifier::Attribute,
+        HighlightModifier::ControlFlow,
+        HighlightModifier::Definition,
+        HighlightModifier::Documentation,
+        HighlightModifier::Injected,
+        HighlightModifier::Mutable,
+        HighlightModifier::Consuming,
+        HighlightModifier::Unsafe,
+    ];
+
+    fn as_str(self) -> &'static str {
+        match self {
+            HighlightModifier::Attribute => "attribute",
+            HighlightModifier::ControlFlow => "control",
+            HighlightModifier::Definition => "declaration",
+            HighlightModifier::Documentation => "documentation",
+            HighlightModifier::Injected => "injected",
+            HighlightModifier::Mutable => "mutable",
+            HighlightModifier::Consuming => "consuming",
+            HighlightModifier::Unsafe => "unsafe",
+        }
+    }
+
+    fn mask(self) -> u32 {
+        1 << (self as u32)
+    }
+}
+
+impl fmt::Display for HighlightModifier {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self.as_str(), f)
+    }
+}
+
+impl fmt::Display for Highlight {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.tag)?;
+        for modifier in self.modifiers.iter() {
+            write!(f, ".{}", modifier)?
+        }
+        Ok(())
+    }
+}
+
+impl From<HighlightTag> for Highlight {
+    fn from(tag: HighlightTag) -> Highlight {
+        Highlight::new(tag)
+    }
+}
+
+impl Highlight {
+    pub(crate) fn new(tag: HighlightTag) -> Highlight {
+        Highlight { tag, modifiers: HighlightModifiers::default() }
+    }
+}
+
+impl ops::BitOr<HighlightModifier> for HighlightTag {
+    type Output = Highlight;
+
+    fn bitor(self, rhs: HighlightModifier) -> Highlight {
+        Highlight::new(self) | rhs
+    }
+}
+
+impl ops::BitOrAssign<HighlightModifier> for HighlightModifiers {
+    fn bitor_assign(&mut self, rhs: HighlightModifier) {
+        self.0 |= rhs.mask();
+    }
+}
+
+impl ops::BitOrAssign<HighlightModifier> for Highlight {
+    fn bitor_assign(&mut self, rhs: HighlightModifier) {
+        self.modifiers |= rhs;
+    }
+}
+
+impl ops::BitOr<HighlightModifier> for Highlight {
+    type Output = Highlight;
+
+    fn bitor(mut self, rhs: HighlightModifier) -> Highlight {
+        self |= rhs;
+        self
+    }
+}
+
+impl HighlightModifiers {
+    pub fn iter(self) -> impl Iterator<Item = HighlightModifier> {
+        HighlightModifier::ALL.iter().copied().filter(move |it| self.0 & it.mask() == it.mask())
+    }
+}
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
new file mode 100644
index 000000000..1c3fea058
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -0,0 +1,484 @@
+use std::fs;
+
+use expect_test::{expect_file, ExpectFile};
+use test_utils::project_dir;
+
+use crate::{mock_analysis::single_file, FileRange, TextRange};
+
+#[test]
+fn test_highlighting() {
+    check_highlighting(
+        r#"
+use inner::{self as inner_mod};
+mod inner {}
+
+// Needed for function consuming vs normal
+pub mod marker {
+    #[lang = "copy"]
+    pub trait Copy {}
+}
+
+#[derive(Clone, Debug)]
+struct Foo {
+    pub x: i32,
+    pub y: i32,
+}
+
+trait Bar {
+    fn bar(&self) -> i32;
+}
+
+impl Bar for Foo {
+    fn bar(&self) -> i32 {
+        self.x
+    }
+}
+
+impl Foo {
+    fn baz(mut self) -> i32 {
+        self.x
+    }
+
+    fn qux(&mut self) {
+        self.x = 0;
+    }
+
+    fn quop(&self) -> i32 {
+        self.x
+    }
+}
+
+#[derive(Copy, Clone)]
+struct FooCopy {
+    x: u32,
+}
+
+impl FooCopy {
+    fn baz(self) -> u32 {
+        self.x
+    }
+
+    fn qux(&mut self) {
+        self.x = 0;
+    }
+
+    fn quop(&self) -> u32 {
+        self.x
+    }
+}
+
+static mut STATIC_MUT: i32 = 0;
+
+fn foo<'a, T>() -> T {
+    foo::<'a, i32>()
+}
+
+macro_rules! def_fn {
+    ($($tt:tt)*) => {$($tt)*}
+}
+
+def_fn! {
+    fn bar() -> u32 {
+        100
+    }
+}
+
+macro_rules! noop {
+    ($expr:expr) => {
+        $expr
+    }
+}
+
+// comment
+fn main() {
+    println!("Hello, {}!", 92);
+
+    let mut vec = Vec::new();
+    if true {
+        let x = 92;
+        vec.push(Foo { x, y: 1 });
+    }
+    unsafe {
+        vec.set_len(0);
+        STATIC_MUT = 1;
+    }
+
+    for e in vec {
+        // Do nothing
+    }
+
+    noop!(noop!(1));
+
+    let mut x = 42;
+    let y = &mut x;
+    let z = &y;
+
+    let Foo { x: z, y } = Foo { x: z, y };
+
+    y;
+
+    let mut foo = Foo { x, y: x };
+    foo.quop();
+    foo.qux();
+    foo.baz();
+
+    let mut copy = FooCopy { x };
+    copy.quop();
+    copy.qux();
+    copy.baz();
+}
+
+enum Option<T> {
+    Some(T),
+    None,
+}
+use Option::*;
+
+impl<T> Option<T> {
+    fn and<U>(self, other: Option<U>) -> Option<(T, U)> {
+        match other {
+            None => unimplemented!(),
+            Nope => Nope,
+        }
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlighting.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_rainbow_highlighting() {
+    check_highlighting(
+        r#"
+fn main() {
+    let hello = "hello";
+    let x = hello.to_string();
+    let y = hello.to_string();
+
+    let x = "other color please!";
+    let y = x.to_string();
+}
+
+fn bar() {
+    let mut hello = "hello";
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/rainbow_highlighting.html"],
+        true,
+    );
+}
+
+#[test]
+fn accidentally_quadratic() {
+    let file = project_dir().join("crates/syntax/test_data/accidentally_quadratic");
+    let src = fs::read_to_string(file).unwrap();
+
+    let (analysis, file_id) = single_file(&src);
+
+    // let t = std::time::Instant::now();
+    let _ = analysis.highlight(file_id).unwrap();
+    // eprintln!("elapsed: {:?}", t.elapsed());
+}
+
+#[test]
+fn test_ranges() {
+    let (analysis, file_id) = single_file(
+        r#"
+#[derive(Clone, Debug)]
+struct Foo {
+    pub x: i32,
+    pub y: i32,
+}
+"#,
+    );
+
+    // The "x"
+    let highlights = &analysis
+        .highlight_range(FileRange { file_id, range: TextRange::at(45.into(), 1.into()) })
+        .unwrap();
+
+    assert_eq!(&highlights[0].highlight.to_string(), "field.declaration");
+}
+
+#[test]
+fn test_flattening() {
+    check_highlighting(
+        r##"
+fn fixture(ra_fixture: &str) {}
+
+fn main() {
+    fixture(r#"
+        trait Foo {
+            fn foo() {
+                println!("2 + 2 = {}", 4);
+            }
+        }"#
+    );
+}"##
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_injection.html"],
+        false,
+    );
+}
+
+#[test]
+fn ranges_sorted() {
+    let (analysis, file_id) = single_file(
+        r#"
+#[foo(bar = "bar")]
+macro_rules! test {}
+}"#
+        .trim(),
+    );
+    let _ = analysis.highlight(file_id).unwrap();
+}
+
+#[test]
+fn test_string_highlighting() {
+    // The format string detection is based on macro-expansion,
+    // thus, we have to copy the macro definition from `std`
+    check_highlighting(
+        r#"
+macro_rules! println {
+    ($($arg:tt)*) => ({
+        $crate::io::_print($crate::format_args_nl!($($arg)*));
+    })
+}
+#[rustc_builtin_macro]
+macro_rules! format_args_nl {
+    ($fmt:expr) => {{ /* compiler built-in */ }};
+    ($fmt:expr, $($args:tt)*) => {{ /* compiler built-in */ }};
+}
+
+fn main() {
+    // from https://doc.rust-lang.org/std/fmt/index.html
+    println!("Hello");                 // => "Hello"
+    println!("Hello, {}!", "world");   // => "Hello, world!"
+    println!("The number is {}", 1);   // => "The number is 1"
+    println!("{:?}", (3, 4));          // => "(3, 4)"
+    println!("{value}", value=4);      // => "4"
+    println!("{} {}", 1, 2);           // => "1 2"
+    println!("{:04}", 42);             // => "0042" with leading zerosV
+    println!("{1} {} {0} {}", 1, 2);   // => "2 1 1 2"
+    println!("{argument}", argument = "test");   // => "test"
+    println!("{name} {}", 1, name = 2);          // => "2 1"
+    println!("{a} {c} {b}", a="a", b='b', c=3);  // => "a 3 b"
+    println!("{{{}}}", 2);                       // => "{2}"
+    println!("Hello {:5}!", "x");
+    println!("Hello {:1$}!", "x", 5);
+    println!("Hello {1:0$}!", 5, "x");
+    println!("Hello {:width$}!", "x", width = 5);
+    println!("Hello {:<5}!", "x");
+    println!("Hello {:-<5}!", "x");
+    println!("Hello {:^5}!", "x");
+    println!("Hello {:>5}!", "x");
+    println!("Hello {:+}!", 5);
+    println!("{:#x}!", 27);
+    println!("Hello {:05}!", 5);
+    println!("Hello {:05}!", -5);
+    println!("{:#010x}!", 27);
+    println!("Hello {0} is {1:.5}", "x", 0.01);
+    println!("Hello {1} is {2:.0$}", 5, "x", 0.01);
+    println!("Hello {0} is {2:.1$}", "x", 5, 0.01);
+    println!("Hello {} is {:.*}",    "x", 5, 0.01);
+    println!("Hello {} is {2:.*}",   "x", 5, 0.01);
+    println!("Hello {} is {number:.prec$}", "x", prec = 5, number = 0.01);
+    println!("{}, `{name:.*}` has 3 fractional digits", "Hello", 3, name=1234.56);
+    println!("{}, `{name:.*}` has 3 characters", "Hello", 3, name="1234.56");
+    println!("{}, `{name:>8.*}` has 3 right-aligned characters", "Hello", 3, name="1234.56");
+    println!("Hello {{}}");
+    println!("{{ Hello");
+
+    println!(r"Hello, {}!", "world");
+
+    // escape sequences
+    println!("Hello\nWorld");
+    println!("\u{48}\x65\x6C\x6C\x6F World");
+
+    println!("{\x41}", A = 92);
+    println!("{ничоси}", ничоси = 92);
+}"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_strings.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_unsafe_highlighting() {
+    check_highlighting(
+        r#"
+unsafe fn unsafe_fn() {}
+
+union Union {
+    a: u32,
+    b: f32,
+}
+
+struct HasUnsafeFn;
+
+impl HasUnsafeFn {
+    unsafe fn unsafe_method(&self) {}
+}
+
+struct TypeForStaticMut {
+    a: u8
+}
+
+static mut global_mut: TypeForStaticMut = TypeForStaticMut { a: 0 };
+
+#[repr(packed)]
+struct Packed {
+    a: u16,
+}
+
+trait DoTheAutoref {
+    fn calls_autoref(&self);
+}
+
+impl DoTheAutoref for u16 {
+    fn calls_autoref(&self) {}
+}
+
+fn main() {
+    let x = &5 as *const _ as *const usize;
+    let u = Union { b: 0 };
+    unsafe {
+        // unsafe fn and method calls
+        unsafe_fn();
+        let b = u.b;
+        match u {
+            Union { b: 0 } => (),
+            Union { a } => (),
+        }
+        HasUnsafeFn.unsafe_method();
+
+        // unsafe deref
+        let y = *x;
+
+        // unsafe access to a static mut
+        let a = global_mut.a;
+
+        // unsafe ref of packed fields
+        let packed = Packed { a: 0 };
+        let a = &packed.a;
+        let ref a = packed.a;
+        let Packed { ref a } = packed;
+        let Packed { a: ref _a } = packed;
+
+        // unsafe auto ref of packed field
+        packed.a.calls_autoref();
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_unsafe.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_highlight_doctest() {
+    check_highlighting(
+        r#"
+/// ```
+/// let _ = "early doctests should not go boom";
+/// ```
+struct Foo {
+    bar: bool,
+}
+
+impl Foo {
+    pub const bar: bool = true;
+
+    /// Constructs a new `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #![allow(unused_mut)]
+    /// let mut foo: Foo = Foo::new();
+    /// ```
+    pub const fn new() -> Foo {
+        Foo { bar: true }
+    }
+
+    /// `bar` method on `Foo`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use x::y;
+    ///
+    /// let foo = Foo::new();
+    ///
+    /// // calls bar on foo
+    /// assert!(foo.bar());
+    ///
+    /// let bar = foo.bar || Foo::bar;
+    ///
+    /// /* multi-line
+    ///        comment */
+    ///
+    /// let multi_line_string = "Foo
+    ///   bar
+    ///          ";
+    ///
+    /// ```
+    ///
+    /// ```rust,no_run
+    /// let foobar = Foo::new().bar();
+    /// ```
+    ///
+    /// ```sh
+    /// echo 1
+    /// ```
+    pub fn foo(&self) -> bool {
+        true
+    }
+}
+
+/// ```
+/// noop!(1);
+/// ```
+macro_rules! noop {
+    ($expr:expr) => {
+        $expr
+    }
+}
+"#
+        .trim(),
+        expect_file!["crates/ide/test_data/highlight_doctest.html"],
+        false,
+    );
+}
+
+#[test]
+fn test_extern_crate() {
+    check_highlighting(
+        r#"
+        //- /main.rs
+        extern crate std;
+        extern crate alloc as abc;
+        //- /std/lib.rs
+        pub struct S;
+        //- /alloc/lib.rs
+        pub struct A
+        "#,
+        expect_file!["crates/ide/test_data/highlight_extern_crate.html"],
+        false,
+    );
+}
+
+/// Highlights the code given by the `ra_fixture` argument, renders the
+/// result as HTML, and compares it with the HTML file given as `snapshot`.
+/// Note that the `snapshot` file is overwritten by the rendered HTML.
+fn check_highlighting(ra_fixture: &str, expect: ExpectFile, rainbow: bool) {
+    let (analysis, file_id) = single_file(ra_fixture);
+    let actual_html = &analysis.highlight_as_html(file_id, rainbow).unwrap();
+    expect.assert_eq(actual_html)
+}
diff --git a/crates/ide/src/syntax_tree.rs b/crates/ide/src/syntax_tree.rs
new file mode 100644
index 000000000..f80044959
--- /dev/null
+++ b/crates/ide/src/syntax_tree.rs
@@ -0,0 +1,359 @@
+use base_db::{FileId, SourceDatabase};
+use ide_db::RootDatabase;
+use syntax::{
+    algo, AstNode, NodeOrToken, SourceFile,
+    SyntaxKind::{RAW_STRING, STRING},
+    SyntaxToken, TextRange, TextSize,
+};
+
+// Feature: Show Syntax Tree
+//
+// Shows the parse tree of the current file. It exists mostly for debugging
+// rust-analyzer itself.
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Show Syntax Tree**
+// |===
+pub(crate) fn syntax_tree(
+    db: &RootDatabase,
+    file_id: FileId,
+    text_range: Option<TextRange>,
+) -> String {
+    let parse = db.parse(file_id);
+    if let Some(text_range) = text_range {
+        let node = match algo::find_covering_element(parse.tree().syntax(), text_range) {
+            NodeOrToken::Node(node) => node,
+            NodeOrToken::Token(token) => {
+                if let Some(tree) = syntax_tree_for_string(&token, text_range) {
+                    return tree;
+                }
+                token.parent()
+            }
+        };
+
+        format!("{:#?}", node)
+    } else {
+        format!("{:#?}", parse.tree().syntax())
+    }
+}
+
+/// Attempts parsing the selected contents of a string literal
+/// as rust syntax and returns its syntax tree
+fn syntax_tree_for_string(token: &SyntaxToken, text_range: TextRange) -> Option<String> {
+    // When the range is inside a string
+    // we'll attempt parsing it as rust syntax
+    // to provide the syntax tree of the contents of the string
+    match token.kind() {
+        STRING | RAW_STRING => syntax_tree_for_token(token, text_range),
+        _ => None,
+    }
+}
+
+fn syntax_tree_for_token(node: &SyntaxToken, text_range: TextRange) -> Option<String> {
+    // Range of the full node
+    let node_range = node.text_range();
+    let text = node.text().to_string();
+
+    // We start at some point inside the node
+    // Either we have selected the whole string
+    // or our selection is inside it
+    let start = text_range.start() - node_range.start();
+
+    // how many characters we have selected
+    let len = text_range.len();
+
+    let node_len = node_range.len();
+
+    let start = start;
+
+    // We want to cap our length
+    let len = len.min(node_len);
+
+    // Ensure our slice is inside the actual string
+    let end =
+        if start + len < TextSize::of(&text) { start + len } else { TextSize::of(&text) - start };
+
+    let text = &text[TextRange::new(start, end)];
+
+    // Remove possible extra string quotes from the start
+    // and the end of the string
+    let text = text
+        .trim_start_matches('r')
+        .trim_start_matches('#')
+        .trim_start_matches('"')
+        .trim_end_matches('#')
+        .trim_end_matches('"')
+        .trim()
+        // Remove custom markers
+        .replace("<|>", "");
+
+    let parsed = SourceFile::parse(&text);
+
+    // If the "file" parsed without errors,
+    // return its syntax
+    if parsed.errors().is_empty() {
+        return Some(format!("{:#?}", parsed.tree().syntax()));
+    }
+
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::assert_eq_text;
+
+    use crate::mock_analysis::{analysis_and_range, single_file};
+
+    #[test]
+    fn test_syntax_tree_without_range() {
+        // Basic syntax
+        let (analysis, file_id) = single_file(r#"fn foo() {}"#);
+        let syn = analysis.syntax_tree(file_id, None).unwrap();
+
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "foo"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "}"
+"#
+            .trim()
+        );
+
+        let (analysis, file_id) = single_file(
+            r#"
+fn test() {
+    assert!("
+    fn foo() {
+    }
+    ", "");
+}"#
+            .trim(),
+        );
+        let syn = analysis.syntax_tree(file_id, None).unwrap();
+
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "test"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n    "
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "assert"
+          [email protected] "!"
+          [email protected]
+            [email protected] "("
+            [email protected] "\"\n    fn foo() {\n     ..."
+            [email protected] ","
+            [email protected] " "
+            [email protected] "\"\""
+            [email protected] ")"
+        [email protected] ";"
+      [email protected] "\n"
+      [email protected] "}"
+"#
+            .trim()
+        );
+    }
+
+    #[test]
+    fn test_syntax_tree_with_range() {
+        let (analysis, range) = analysis_and_range(r#"<|>fn foo() {}<|>"#.trim());
+        let syn = analysis.syntax_tree(range.file_id, Some(range.range)).unwrap();
+
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected] "fn"
+  [email protected] " "
+  [email protected]
+    [email protected] "foo"
+  [email protected]
+    [email protected] "("
+    [email protected] ")"
+  [email protected] " "
+  [email protected]
+    [email protected] "{"
+    [email protected] "}"
+"#
+            .trim()
+        );
+
+        let (analysis, range) = analysis_and_range(
+            r#"fn test() {
+    <|>assert!("
+    fn foo() {
+    }
+    ", "");<|>
+}"#
+            .trim(),
+        );
+        let syn = analysis.syntax_tree(range.file_id, Some(range.range)).unwrap();
+
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected] "assert"
+    [email protected] "!"
+    [email protected]
+      [email protected] "("
+      [email protected] "\"\n    fn foo() {\n     ..."
+      [email protected] ","
+      [email protected] " "
+      [email protected] "\"\""
+      [email protected] ")"
+  [email protected] ";"
+"#
+            .trim()
+        );
+    }
+
+    #[test]
+    fn test_syntax_tree_inside_string() {
+        let (analysis, range) = analysis_and_range(
+            r#"fn test() {
+    assert!("
+<|>fn foo() {
+}<|>
+fn bar() {
+}
+    ", "");
+}"#
+            .trim(),
+        );
+        let syn = analysis.syntax_tree(range.file_id, Some(range.range)).unwrap();
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "foo"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
+"#
+            .trim()
+        );
+
+        // With a raw string
+        let (analysis, range) = analysis_and_range(
+            r###"fn test() {
+    assert!(r#"
+<|>fn foo() {
+}<|>
+fn bar() {
+}
+    "#, "");
+}"###
+                .trim(),
+        );
+        let syn = analysis.syntax_tree(range.file_id, Some(range.range)).unwrap();
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "foo"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
+"#
+            .trim()
+        );
+
+        // With a raw string
+        let (analysis, range) = analysis_and_range(
+            r###"fn test() {
+    assert!(r<|>#"
+fn foo() {
+}
+fn bar() {
+}"<|>#, "");
+}"###
+                .trim(),
+        );
+        let syn = analysis.syntax_tree(range.file_id, Some(range.range)).unwrap();
+        assert_eq_text!(
+            syn.trim(),
+            r#"
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "foo"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
+  [email protected] "\n"
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "bar"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n"
+      [email protected] "}"
+"#
+            .trim()
+        );
+    }
+}
diff --git a/crates/ide/src/typing.rs b/crates/ide/src/typing.rs
new file mode 100644
index 000000000..899ce5f26
--- /dev/null
+++ b/crates/ide/src/typing.rs
@@ -0,0 +1,364 @@
+//! This module handles auto-magic editing actions applied together with users
+//! edits. For example, if the user typed
+//!
+//! ```text
+//!     foo
+//!         .bar()
+//!         .baz()
+//!     |   // <- cursor is here
+//! ```
+//!
+//! and types `.` next, we want to indent the dot.
+//!
+//! Language server executes such typing assists synchronously. That is, they
+//! block user's typing and should be pretty fast for this reason!
+
+mod on_enter;
+
+use base_db::{FilePosition, SourceDatabase};
+use ide_db::{source_change::SourceFileEdit, RootDatabase};
+use syntax::{
+    algo::find_node_at_offset,
+    ast::{self, edit::IndentLevel, AstToken},
+    AstNode, SourceFile,
+    SyntaxKind::{FIELD_EXPR, METHOD_CALL_EXPR},
+    TextRange, TextSize,
+};
+
+use text_edit::TextEdit;
+
+use crate::SourceChange;
+
+pub(crate) use on_enter::on_enter;
+
+pub(crate) const TRIGGER_CHARS: &str = ".=>";
+
+// Feature: On Typing Assists
+//
+// Some features trigger on typing certain characters:
+//
+// - typing `let =` tries to smartly add `;` if `=` is followed by an existing expression
+// - typing `.` in a chain method call auto-indents
+pub(crate) fn on_char_typed(
+    db: &RootDatabase,
+    position: FilePosition,
+    char_typed: char,
+) -> Option<SourceChange> {
+    assert!(TRIGGER_CHARS.contains(char_typed));
+    let file = &db.parse(position.file_id).tree();
+    assert_eq!(file.syntax().text().char_at(position.offset), Some(char_typed));
+    let edit = on_char_typed_inner(file, position.offset, char_typed)?;
+    Some(SourceFileEdit { file_id: position.file_id, edit }.into())
+}
+
+fn on_char_typed_inner(file: &SourceFile, offset: TextSize, char_typed: char) -> Option<TextEdit> {
+    assert!(TRIGGER_CHARS.contains(char_typed));
+    match char_typed {
+        '.' => on_dot_typed(file, offset),
+        '=' => on_eq_typed(file, offset),
+        '>' => on_arrow_typed(file, offset),
+        _ => unreachable!(),
+    }
+}
+
+/// Returns an edit which should be applied after `=` was typed. Primarily,
+/// this works when adding `let =`.
+// FIXME: use a snippet completion instead of this hack here.
+fn on_eq_typed(file: &SourceFile, offset: TextSize) -> Option<TextEdit> {
+    assert_eq!(file.syntax().text().char_at(offset), Some('='));
+    let let_stmt: ast::LetStmt = find_node_at_offset(file.syntax(), offset)?;
+    if let_stmt.semicolon_token().is_some() {
+        return None;
+    }
+    if let Some(expr) = let_stmt.initializer() {
+        let expr_range = expr.syntax().text_range();
+        if expr_range.contains(offset) && offset != expr_range.start() {
+            return None;
+        }
+        if file.syntax().text().slice(offset..expr_range.start()).contains_char('\n') {
+            return None;
+        }
+    } else {
+        return None;
+    }
+    let offset = let_stmt.syntax().text_range().end();
+    Some(TextEdit::insert(offset, ";".to_string()))
+}
+
+/// Returns an edit which should be applied when a dot ('.') is typed on a blank line, indenting the line appropriately.
+fn on_dot_typed(file: &SourceFile, offset: TextSize) -> Option<TextEdit> {
+    assert_eq!(file.syntax().text().char_at(offset), Some('.'));
+    let whitespace =
+        file.syntax().token_at_offset(offset).left_biased().and_then(ast::Whitespace::cast)?;
+
+    let current_indent = {
+        let text = whitespace.text();
+        let newline = text.rfind('\n')?;
+        &text[newline + 1..]
+    };
+    let current_indent_len = TextSize::of(current_indent);
+
+    let parent = whitespace.syntax().parent();
+    // Make sure dot is a part of call chain
+    if !matches!(parent.kind(), FIELD_EXPR | METHOD_CALL_EXPR) {
+        return None;
+    }
+    let prev_indent = IndentLevel::from_node(&parent);
+    let target_indent = format!("    {}", prev_indent);
+    let target_indent_len = TextSize::of(&target_indent);
+    if current_indent_len == target_indent_len {
+        return None;
+    }
+
+    Some(TextEdit::replace(TextRange::new(offset - current_indent_len, offset), target_indent))
+}
+
+/// Adds a space after an arrow when `fn foo() { ... }` is turned into `fn foo() -> { ... }`
+fn on_arrow_typed(file: &SourceFile, offset: TextSize) -> Option<TextEdit> {
+    let file_text = file.syntax().text();
+    assert_eq!(file_text.char_at(offset), Some('>'));
+    let after_arrow = offset + TextSize::of('>');
+    if file_text.char_at(after_arrow) != Some('{') {
+        return None;
+    }
+    if find_node_at_offset::<ast::RetType>(file.syntax(), offset).is_none() {
+        return None;
+    }
+
+    Some(TextEdit::insert(after_arrow, " ".to_string()))
+}
+
+#[cfg(test)]
+mod tests {
+    use test_utils::{assert_eq_text, extract_offset};
+
+    use super::*;
+
+    fn do_type_char(char_typed: char, before: &str) -> Option<String> {
+        let (offset, before) = extract_offset(before);
+        let edit = TextEdit::insert(offset, char_typed.to_string());
+        let mut before = before.to_string();
+        edit.apply(&mut before);
+        let parse = SourceFile::parse(&before);
+        on_char_typed_inner(&parse.tree(), offset, char_typed).map(|it| {
+            it.apply(&mut before);
+            before.to_string()
+        })
+    }
+
+    fn type_char(char_typed: char, ra_fixture_before: &str, ra_fixture_after: &str) {
+        let actual = do_type_char(char_typed, ra_fixture_before)
+            .unwrap_or_else(|| panic!("typing `{}` did nothing", char_typed));
+
+        assert_eq_text!(ra_fixture_after, &actual);
+    }
+
+    fn type_char_noop(char_typed: char, before: &str) {
+        let file_change = do_type_char(char_typed, before);
+        assert!(file_change.is_none())
+    }
+
+    #[test]
+    fn test_on_eq_typed() {
+        //     do_check(r"
+        // fn foo() {
+        //     let foo =<|>
+        // }
+        // ", r"
+        // fn foo() {
+        //     let foo =;
+        // }
+        // ");
+        type_char(
+            '=',
+            r"
+fn foo() {
+    let foo <|> 1 + 1
+}
+",
+            r"
+fn foo() {
+    let foo = 1 + 1;
+}
+",
+        );
+        //     do_check(r"
+        // fn foo() {
+        //     let foo =<|>
+        //     let bar = 1;
+        // }
+        // ", r"
+        // fn foo() {
+        //     let foo =;
+        //     let bar = 1;
+        // }
+        // ");
+    }
+
+    #[test]
+    fn indents_new_chain_call() {
+        type_char(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                <|>
+            }
+            ",
+            r"
+            fn main() {
+                xs.foo()
+                    .
+            }
+            ",
+        );
+        type_char_noop(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                    <|>
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn indents_new_chain_call_with_semi() {
+        type_char(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                <|>;
+            }
+            ",
+            r"
+            fn main() {
+                xs.foo()
+                    .;
+            }
+            ",
+        );
+        type_char_noop(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                    <|>;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn indents_new_chain_call_with_let() {
+        type_char(
+            '.',
+            r#"
+fn main() {
+    let _ = foo
+    <|>
+    bar()
+}
+"#,
+            r#"
+fn main() {
+    let _ = foo
+        .
+    bar()
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn indents_continued_chain_call() {
+        type_char(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                    .first()
+                <|>
+            }
+            ",
+            r"
+            fn main() {
+                xs.foo()
+                    .first()
+                    .
+            }
+            ",
+        );
+        type_char_noop(
+            '.',
+            r"
+            fn main() {
+                xs.foo()
+                    .first()
+                    <|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn indents_middle_of_chain_call() {
+        type_char(
+            '.',
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    .
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+        type_char_noop(
+            '.',
+            r"
+            fn source_impl() {
+                let var = enum_defvariant_list().unwrap()
+                    <|>
+                    .nth(92)
+                    .unwrap();
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn dont_indent_freestanding_dot() {
+        type_char_noop(
+            '.',
+            r"
+            fn main() {
+                <|>
+            }
+            ",
+        );
+        type_char_noop(
+            '.',
+            r"
+            fn main() {
+            <|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn adds_space_after_return_type() {
+        type_char('>', "fn foo() -<|>{ 92 }", "fn foo() -> { 92 }")
+    }
+}
diff --git a/crates/ide/src/typing/on_enter.rs b/crates/ide/src/typing/on_enter.rs
new file mode 100644
index 000000000..f7d46146c
--- /dev/null
+++ b/crates/ide/src/typing/on_enter.rs
@@ -0,0 +1,256 @@
+//! Handles the `Enter` key press. At the momently, this only continues
+//! comments, but should handle indent some time in the future as well.
+
+use base_db::{FilePosition, SourceDatabase};
+use ide_db::RootDatabase;
+use syntax::{
+    ast::{self, AstToken},
+    AstNode, SmolStr, SourceFile,
+    SyntaxKind::*,
+    SyntaxToken, TextRange, TextSize, TokenAtOffset,
+};
+use test_utils::mark;
+use text_edit::TextEdit;
+
+// Feature: On Enter
+//
+// rust-analyzer can override kbd:[Enter] key to make it smarter:
+//
+// - kbd:[Enter] inside triple-slash comments automatically inserts `///`
+// - kbd:[Enter] in the middle or after a trailing space in `//` inserts `//`
+//
+// This action needs to be assigned to shortcut explicitly.
+//
+// VS Code::
+//
+// Add the following to `keybindings.json`:
+// [source,json]
+// ----
+// {
+//   "key": "Enter",
+//   "command": "rust-analyzer.onEnter",
+//   "when": "editorTextFocus && !suggestWidgetVisible && editorLangId == rust"
+// }
+// ----
+pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<TextEdit> {
+    let parse = db.parse(position.file_id);
+    let file = parse.tree();
+    let comment = file
+        .syntax()
+        .token_at_offset(position.offset)
+        .left_biased()
+        .and_then(ast::Comment::cast)?;
+
+    if comment.kind().shape.is_block() {
+        return None;
+    }
+
+    let prefix = comment.prefix();
+    let comment_range = comment.syntax().text_range();
+    if position.offset < comment_range.start() + TextSize::of(prefix) {
+        return None;
+    }
+
+    let mut remove_last_space = false;
+    // Continuing single-line non-doc comments (like this one :) ) is annoying
+    if prefix == "//" && comment_range.end() == position.offset {
+        if comment.text().ends_with(' ') {
+            mark::hit!(continues_end_of_line_comment_with_space);
+            remove_last_space = true;
+        } else if !followed_by_comment(&comment) {
+            return None;
+        }
+    }
+
+    let indent = node_indent(&file, comment.syntax())?;
+    let inserted = format!("\n{}{} $0", indent, prefix);
+    let delete = if remove_last_space {
+        TextRange::new(position.offset - TextSize::of(' '), position.offset)
+    } else {
+        TextRange::empty(position.offset)
+    };
+    let edit = TextEdit::replace(delete, inserted);
+    Some(edit)
+}
+
+fn followed_by_comment(comment: &ast::Comment) -> bool {
+    let ws = match comment.syntax().next_token().and_then(ast::Whitespace::cast) {
+        Some(it) => it,
+        None => return false,
+    };
+    if ws.spans_multiple_lines() {
+        return false;
+    }
+    ws.syntax().next_token().and_then(ast::Comment::cast).is_some()
+}
+
+fn node_indent(file: &SourceFile, token: &SyntaxToken) -> Option<SmolStr> {
+    let ws = match file.syntax().token_at_offset(token.text_range().start()) {
+        TokenAtOffset::Between(l, r) => {
+            assert!(r == *token);
+            l
+        }
+        TokenAtOffset::Single(n) => {
+            assert!(n == *token);
+            return Some("".into());
+        }
+        TokenAtOffset::None => unreachable!(),
+    };
+    if ws.kind() != WHITESPACE {
+        return None;
+    }
+    let text = ws.text();
+    let pos = text.rfind('\n').map(|it| it + 1).unwrap_or(0);
+    Some(text[pos..].into())
+}
+
+#[cfg(test)]
+mod tests {
+    use stdx::trim_indent;
+    use test_utils::{assert_eq_text, mark};
+
+    use crate::mock_analysis::analysis_and_position;
+
+    fn apply_on_enter(before: &str) -> Option<String> {
+        let (analysis, position) = analysis_and_position(&before);
+        let result = analysis.on_enter(position).unwrap()?;
+
+        let mut actual = analysis.file_text(position.file_id).unwrap().to_string();
+        result.apply(&mut actual);
+        Some(actual)
+    }
+
+    fn do_check(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let ra_fixture_after = &trim_indent(ra_fixture_after);
+        let actual = apply_on_enter(ra_fixture_before).unwrap();
+        assert_eq_text!(ra_fixture_after, &actual);
+    }
+
+    fn do_check_noop(ra_fixture_text: &str) {
+        assert!(apply_on_enter(ra_fixture_text).is_none())
+    }
+
+    #[test]
+    fn continues_doc_comment() {
+        do_check(
+            r"
+/// Some docs<|>
+fn foo() {
+}
+",
+            r"
+/// Some docs
+/// $0
+fn foo() {
+}
+",
+        );
+
+        do_check(
+            r"
+impl S {
+    /// Some<|> docs.
+    fn foo() {}
+}
+",
+            r"
+impl S {
+    /// Some
+    /// $0 docs.
+    fn foo() {}
+}
+",
+        );
+
+        do_check(
+            r"
+///<|> Some docs
+fn foo() {
+}
+",
+            r"
+///
+/// $0 Some docs
+fn foo() {
+}
+",
+        );
+    }
+
+    #[test]
+    fn does_not_continue_before_doc_comment() {
+        do_check_noop(r"<|>//! docz");
+    }
+
+    #[test]
+    fn continues_code_comment_in_the_middle_of_line() {
+        do_check(
+            r"
+fn main() {
+    // Fix<|> me
+    let x = 1 + 1;
+}
+",
+            r"
+fn main() {
+    // Fix
+    // $0 me
+    let x = 1 + 1;
+}
+",
+        );
+    }
+
+    #[test]
+    fn continues_code_comment_in_the_middle_several_lines() {
+        do_check(
+            r"
+fn main() {
+    // Fix<|>
+    // me
+    let x = 1 + 1;
+}
+",
+            r"
+fn main() {
+    // Fix
+    // $0
+    // me
+    let x = 1 + 1;
+}
+",
+        );
+    }
+
+    #[test]
+    fn does_not_continue_end_of_line_comment() {
+        do_check_noop(
+            r"
+fn main() {
+    // Fix me<|>
+    let x = 1 + 1;
+}
+",
+        );
+    }
+
+    #[test]
+    fn continues_end_of_line_comment_with_space() {
+        mark::check!(continues_end_of_line_comment_with_space);
+        do_check(
+            r#"
+fn main() {
+    // Fix me <|>
+    let x = 1 + 1;
+}
+"#,
+            r#"
+fn main() {
+    // Fix me
+    // $0
+    let x = 1 + 1;
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/test_data/highlight_doctest.html b/crates/ide/test_data/highlight_doctest.html
new file mode 100644
index 000000000..6322d404f
--- /dev/null
+++ b/crates/ide/test_data/highlight_doctest.html
@@ -0,0 +1,102 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="comment documentation">/// ```</span>
+<span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="punctuation injected">_</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="string_literal injected">"early doctests should not go boom"</span><span class="punctuation injected">;</span><span class="punctuation injected">
+</span><span class="comment documentation">/// ```</span>
+<span class="keyword">struct</span> <span class="struct declaration">Foo</span> <span class="punctuation">{</span>
+    <span class="field declaration">bar</span><span class="punctuation">:</span> <span class="builtin_type">bool</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="constant declaration">bar</span><span class="punctuation">:</span> <span class="builtin_type">bool</span> <span class="operator">=</span> <span class="bool_literal">true</span><span class="punctuation">;</span>
+
+    <span class="comment documentation">/// Constructs a new `Foo`.</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// # Examples</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// ```</span>
+    <span class="comment documentation">/// #</span><span class="generic injected"> </span><span class="attribute injected">#</span><span class="attribute injected">!</span><span class="attribute injected">[</span><span class="function attribute injected">allow</span><span class="punctuation injected">(</span><span class="attribute injected">unused_mut</span><span class="punctuation injected">)</span><span class="attribute injected">]</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="keyword injected">mut</span><span class="generic injected"> </span><span class="variable declaration injected mutable">foo</span><span class="punctuation injected">:</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="function injected">new</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span><span class="punctuation injected">
+</span>    <span class="comment documentation">/// ```</span>
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
+        <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">bar</span><span class="punctuation">:</span> <span class="bool_literal">true</span> <span class="punctuation">}</span>
+    <span class="punctuation">}</span>
+
+    <span class="comment documentation">/// `bar` method on `Foo`.</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// # Examples</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// ```</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">use</span><span class="generic injected"> </span><span class="module injected">x</span><span class="operator injected">::</span><span class="module injected">y</span><span class="punctuation injected">;</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="variable declaration injected">foo</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="function injected">new</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// </span><span class="comment injected">// calls bar on foo</span>
+    <span class="comment documentation">/// </span><span class="macro injected">assert!</span><span class="punctuation injected">(</span><span class="generic injected">foo</span><span class="punctuation injected">.</span><span class="generic injected">bar</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="variable declaration injected">bar</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="variable injected">foo</span><span class="punctuation injected">.</span><span class="field injected">bar</span><span class="generic injected"> </span><span class="operator injected">||</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="constant injected">bar</span><span class="punctuation injected">;</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// </span><span class="comment injected">/* multi-line
+    </span><span class="comment documentation">/// </span><span class="comment injected">       comment */</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="variable declaration injected">multi_line_string</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="string_literal injected">"Foo
+    </span><span class="comment documentation">/// </span><span class="string_literal injected">  bar
+    </span><span class="comment documentation">/// </span><span class="string_literal injected">         "</span><span class="punctuation injected">;</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// ```</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// ```rust,no_run</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="variable declaration injected">foobar</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="function injected">new</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">.</span><span class="function injected">bar</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span><span class="punctuation injected">
+</span>    <span class="comment documentation">/// ```</span>
+    <span class="comment documentation">///</span>
+    <span class="comment documentation">/// ```sh</span>
+    <span class="comment documentation">/// echo 1</span>
+    <span class="comment documentation">/// ```</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">bool</span> <span class="punctuation">{</span>
+        <span class="bool_literal">true</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="comment documentation">/// ```</span>
+<span class="comment documentation">/// </span><span class="macro injected">noop!</span><span class="punctuation injected">(</span><span class="numeric_literal injected">1</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span><span class="punctuation injected">
+</span><span class="comment documentation">/// ```</span>
+<span class="macro">macro_rules!</span> <span class="macro declaration">noop</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span>expr<span class="punctuation">:</span>expr<span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
+        <span class="punctuation">$</span>expr
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span></code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/highlight_extern_crate.html b/crates/ide/test_data/highlight_extern_crate.html
new file mode 100644
index 000000000..800d894c7
--- /dev/null
+++ b/crates/ide/test_data/highlight_extern_crate.html
@@ -0,0 +1,40 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword">extern</span> <span class="keyword">crate</span> <span class="module">std</span><span class="punctuation">;</span>
+<span class="keyword">extern</span> <span class="keyword">crate</span> <span class="module">alloc</span> <span class="keyword">as</span> <span class="module">abc</span><span class="punctuation">;</span>
+</code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/highlight_injection.html b/crates/ide/test_data/highlight_injection.html
new file mode 100644
index 000000000..18addd00d
--- /dev/null
+++ b/crates/ide/test_data/highlight_injection.html
@@ -0,0 +1,48 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword">fn</span> <span class="function declaration">fixture</span><span class="punctuation">(</span><span class="value_param declaration">ra_fixture</span><span class="punctuation">:</span> <span class="operator">&</span><span class="builtin_type">str</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="function">fixture</span><span class="punctuation">(</span><span class="string_literal">r#"</span>
+        <span class="keyword">trait</span> <span class="trait declaration">Foo</span> <span class="punctuation">{</span>
+            <span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+                <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"2 + 2 = {}"</span><span class="punctuation">,</span> <span class="numeric_literal">4</span><span class="punctuation">)</span><span class="punctuation">;</span>
+            <span class="punctuation">}</span>
+        <span class="punctuation">}</span><span class="string_literal">"#</span>
+    <span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span></code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/highlight_strings.html b/crates/ide/test_data/highlight_strings.html
new file mode 100644
index 000000000..1b681b2c6
--- /dev/null
+++ b/crates/ide/test_data/highlight_strings.html
@@ -0,0 +1,96 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="macro">macro_rules!</span> <span class="macro declaration">println</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>arg<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">(</span><span class="punctuation">{</span>
+        <span class="punctuation">$</span><span class="keyword">crate</span><span class="punctuation">:</span><span class="punctuation">:</span>io<span class="punctuation">:</span><span class="punctuation">:</span>_print<span class="punctuation">(</span><span class="punctuation">$</span><span class="keyword">crate</span><span class="punctuation">:</span><span class="punctuation">:</span>format_args_nl<span class="punctuation">!</span><span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>arg<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span><span class="punctuation">)</span>
+<span class="punctuation">}</span>
+#[rustc_builtin_macro]
+<span class="macro">macro_rules!</span> <span class="macro declaration">format_args_nl</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span>fmt<span class="punctuation">:</span>expr<span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">{</span> <span class="comment">/* compiler built-in */</span> <span class="punctuation">}</span><span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span>fmt<span class="punctuation">:</span>expr<span class="punctuation">,</span> <span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>args<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">{</span> <span class="comment">/* compiler built-in */</span> <span class="punctuation">}</span><span class="punctuation">}</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="comment">// from https://doc.rust-lang.org/std/fmt/index.html</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello"</span><span class="punctuation">)</span><span class="punctuation">;</span>                 <span class="comment">// =&gt; "Hello"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello, </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"world"</span><span class="punctuation">)</span><span class="punctuation">;</span>   <span class="comment">// =&gt; "Hello, world!"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"The number is </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">1</span><span class="punctuation">)</span><span class="punctuation">;</span>   <span class="comment">// =&gt; "The number is 1"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">?</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="punctuation">(</span><span class="numeric_literal">3</span><span class="punctuation">,</span> <span class="numeric_literal">4</span><span class="punctuation">)</span><span class="punctuation">)</span><span class="punctuation">;</span>          <span class="comment">// =&gt; "(3, 4)"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="variable">value</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> value<span class="operator">=</span><span class="numeric_literal">4</span><span class="punctuation">)</span><span class="punctuation">;</span>      <span class="comment">// =&gt; "4"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">1</span><span class="punctuation">,</span> <span class="numeric_literal">2</span><span class="punctuation">)</span><span class="punctuation">;</span>           <span class="comment">// =&gt; "1 2"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="numeric_literal">4</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">42</span><span class="punctuation">)</span><span class="punctuation">;</span>             <span class="comment">// =&gt; "0042" with leading zerosV</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="numeric_literal">1</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="numeric_literal">0</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">1</span><span class="punctuation">,</span> <span class="numeric_literal">2</span><span class="punctuation">)</span><span class="punctuation">;</span>   <span class="comment">// =&gt; "2 1 1 2"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="variable">argument</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> argument <span class="operator">=</span> <span class="string_literal">"test"</span><span class="punctuation">)</span><span class="punctuation">;</span>   <span class="comment">// =&gt; "test"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="variable">name</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">1</span><span class="punctuation">,</span> name <span class="operator">=</span> <span class="numeric_literal">2</span><span class="punctuation">)</span><span class="punctuation">;</span>          <span class="comment">// =&gt; "2 1"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="variable">a</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="variable">c</span><span class="format_specifier">}</span><span class="string_literal"> </span><span class="format_specifier">{</span><span class="variable">b</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> a<span class="operator">=</span><span class="string_literal">"a"</span><span class="punctuation">,</span> b<span class="operator">=</span><span class="char_literal">'b'</span><span class="punctuation">,</span> c<span class="operator">=</span><span class="numeric_literal">3</span><span class="punctuation">)</span><span class="punctuation">;</span>  <span class="comment">// =&gt; "a 3 b"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"{{</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">}}"</span><span class="punctuation">,</span> <span class="numeric_literal">2</span><span class="punctuation">)</span><span class="punctuation">;</span>                       <span class="comment">// =&gt; "{2}"</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">1</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="numeric_literal">1</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="variable">width</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> width <span class="operator">=</span> <span class="numeric_literal">5</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">&lt;</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">-</span><span class="format_specifier">&lt;</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">^</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">&gt;</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">+</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">#</span><span class="variable">x</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="numeric_literal">27</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="numeric_literal">0</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="punctuation">-</span><span class="numeric_literal">5</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">#</span><span class="numeric_literal">0</span><span class="numeric_literal">10</span><span class="variable">x</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="numeric_literal">27</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="numeric_literal">0</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="numeric_literal">1</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="numeric_literal">5</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="numeric_literal">1</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="numeric_literal">2</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="numeric_literal">0</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="numeric_literal">0</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="numeric_literal">2</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="numeric_literal">1</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="format_specifier">*</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span>    <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="numeric_literal">2</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="format_specifier">*</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span>   <span class="string_literal">"x"</span><span class="punctuation">,</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal"> is </span><span class="format_specifier">{</span><span class="variable">number</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="variable">prec</span><span class="format_specifier">$</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> <span class="string_literal">"x"</span><span class="punctuation">,</span> prec <span class="operator">=</span> <span class="numeric_literal">5</span><span class="punctuation">,</span> number <span class="operator">=</span> <span class="numeric_literal">0.01</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">, `</span><span class="format_specifier">{</span><span class="variable">name</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="format_specifier">*</span><span class="format_specifier">}</span><span class="string_literal">` has 3 fractional digits"</span><span class="punctuation">,</span> <span class="string_literal">"Hello"</span><span class="punctuation">,</span> <span class="numeric_literal">3</span><span class="punctuation">,</span> name<span class="operator">=</span><span class="numeric_literal">1234.56</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">, `</span><span class="format_specifier">{</span><span class="variable">name</span><span class="format_specifier">:</span><span class="format_specifier">.</span><span class="format_specifier">*</span><span class="format_specifier">}</span><span class="string_literal">` has 3 characters"</span><span class="punctuation">,</span> <span class="string_literal">"Hello"</span><span class="punctuation">,</span> <span class="numeric_literal">3</span><span class="punctuation">,</span> name<span class="operator">=</span><span class="string_literal">"1234.56"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">, `</span><span class="format_specifier">{</span><span class="variable">name</span><span class="format_specifier">:</span><span class="format_specifier">&gt;</span><span class="numeric_literal">8</span><span class="format_specifier">.</span><span class="format_specifier">*</span><span class="format_specifier">}</span><span class="string_literal">` has 3 right-aligned characters"</span><span class="punctuation">,</span> <span class="string_literal">"Hello"</span><span class="punctuation">,</span> <span class="numeric_literal">3</span><span class="punctuation">,</span> name<span class="operator">=</span><span class="string_literal">"1234.56"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello {{}}"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"{{ Hello"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">r"Hello, </span><span class="format_specifier">{</span><span class="format_specifier">}</span><span class="string_literal">!"</span><span class="punctuation">,</span> <span class="string_literal">"world"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="comment">// escape sequences</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello</span><span class="escape_sequence">\n</span><span class="string_literal">World"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="escape_sequence">\u{48}</span><span class="escape_sequence">\x65</span><span class="escape_sequence">\x6C</span><span class="escape_sequence">\x6C</span><span class="escape_sequence">\x6F</span><span class="string_literal"> World"</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="escape_sequence">\x41</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> A <span class="operator">=</span> <span class="numeric_literal">92</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"</span><span class="format_specifier">{</span><span class="variable">ничоси</span><span class="format_specifier">}</span><span class="string_literal">"</span><span class="punctuation">,</span> ничоси <span class="operator">=</span> <span class="numeric_literal">92</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span></code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/highlight_unsafe.html b/crates/ide/test_data/highlight_unsafe.html
new file mode 100644
index 000000000..552fea668
--- /dev/null
+++ b/crates/ide/test_data/highlight_unsafe.html
@@ -0,0 +1,99 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword unsafe">unsafe</span> <span class="keyword">fn</span> <span class="function declaration unsafe">unsafe_fn</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">union</span> <span class="union declaration">Union</span> <span class="punctuation">{</span>
+    <span class="field declaration">a</span><span class="punctuation">:</span> <span class="builtin_type">u32</span><span class="punctuation">,</span>
+    <span class="field declaration">b</span><span class="punctuation">:</span> <span class="builtin_type">f32</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">struct</span> <span class="struct declaration">HasUnsafeFn</span><span class="punctuation">;</span>
+
+<span class="keyword">impl</span> <span class="struct">HasUnsafeFn</span> <span class="punctuation">{</span>
+    <span class="keyword unsafe">unsafe</span> <span class="keyword">fn</span> <span class="function declaration unsafe">unsafe_method</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">struct</span> <span class="struct declaration">TypeForStaticMut</span> <span class="punctuation">{</span>
+    <span class="field declaration">a</span><span class="punctuation">:</span> <span class="builtin_type">u8</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable unsafe">global_mut</span><span class="punctuation">:</span> <span class="struct">TypeForStaticMut</span> <span class="operator">=</span> <span class="struct">TypeForStaticMut</span> <span class="punctuation">{</span> <span class="field">a</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+
+<span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">repr</span><span class="punctuation">(</span><span class="attribute">packed</span><span class="punctuation">)</span><span class="attribute">]</span>
+<span class="keyword">struct</span> <span class="struct declaration">Packed</span> <span class="punctuation">{</span>
+    <span class="field declaration">a</span><span class="punctuation">:</span> <span class="builtin_type">u16</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">trait</span> <span class="trait declaration">DoTheAutoref</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">calls_autoref</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="trait">DoTheAutoref</span> <span class="keyword">for</span> <span class="builtin_type">u16</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">calls_autoref</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">let</span> <span class="variable declaration">x</span> <span class="operator">=</span> <span class="operator">&</span><span class="numeric_literal">5</span> <span class="keyword">as</span> <span class="keyword">*</span><span class="keyword">const</span> <span class="punctuation">_</span> <span class="keyword">as</span> <span class="keyword">*</span><span class="keyword">const</span> <span class="builtin_type">usize</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration">u</span> <span class="operator">=</span> <span class="union">Union</span> <span class="punctuation">{</span> <span class="field">b</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="keyword unsafe">unsafe</span> <span class="punctuation">{</span>
+        <span class="comment">// unsafe fn and method calls</span>
+        <span class="function unsafe">unsafe_fn</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="variable declaration">b</span> <span class="operator">=</span> <span class="variable">u</span><span class="punctuation">.</span><span class="field unsafe">b</span><span class="punctuation">;</span>
+        <span class="keyword control">match</span> <span class="variable">u</span> <span class="punctuation">{</span>
+            <span class="union">Union</span> <span class="punctuation">{</span> <span class="field unsafe">b</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span> <span class="operator">=&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">,</span>
+            <span class="union">Union</span> <span class="punctuation">{</span> <span class="field unsafe">a</span> <span class="punctuation">}</span> <span class="operator">=&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">,</span>
+        <span class="punctuation">}</span>
+        <span class="struct">HasUnsafeFn</span><span class="punctuation">.</span><span class="function unsafe">unsafe_method</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+        <span class="comment">// unsafe deref</span>
+        <span class="keyword">let</span> <span class="variable declaration">y</span> <span class="operator">=</span> <span class="operator unsafe">*</span><span class="variable">x</span><span class="punctuation">;</span>
+
+        <span class="comment">// unsafe access to a static mut</span>
+        <span class="keyword">let</span> <span class="variable declaration">a</span> <span class="operator">=</span> <span class="static mutable unsafe">global_mut</span><span class="punctuation">.</span><span class="field">a</span><span class="punctuation">;</span>
+
+        <span class="comment">// unsafe ref of packed fields</span>
+        <span class="keyword">let</span> <span class="variable declaration">packed</span> <span class="operator">=</span> <span class="struct">Packed</span> <span class="punctuation">{</span> <span class="field">a</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="variable declaration">a</span> <span class="operator">=</span> <span class="operator unsafe">&</span><span class="variable">packed</span><span class="punctuation">.</span><span class="field">a</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="keyword unsafe">ref</span> <span class="variable declaration">a</span> <span class="operator">=</span> <span class="variable">packed</span><span class="punctuation">.</span><span class="field">a</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="struct">Packed</span> <span class="punctuation">{</span> <span class="keyword unsafe">ref</span> <span class="field">a</span> <span class="punctuation">}</span> <span class="operator">=</span> <span class="variable">packed</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="struct">Packed</span> <span class="punctuation">{</span> <span class="field">a</span><span class="punctuation">:</span> <span class="keyword unsafe">ref</span> <span class="variable declaration">_a</span> <span class="punctuation">}</span> <span class="operator">=</span> <span class="variable">packed</span><span class="punctuation">;</span>
+
+        <span class="comment">// unsafe auto ref of packed field</span>
+        <span class="variable">packed</span><span class="punctuation">.</span><span class="field">a</span><span class="punctuation">.</span><span class="function unsafe">calls_autoref</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span></code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/highlighting.html b/crates/ide/test_data/highlighting.html
new file mode 100644
index 000000000..d0df2e0ec
--- /dev/null
+++ b/crates/ide/test_data/highlighting.html
@@ -0,0 +1,170 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword">use</span> <span class="module">inner</span><span class="operator">::</span><span class="punctuation">{</span><span class="self_keyword">self</span> <span class="keyword">as</span> <span class="module declaration">inner_mod</span><span class="punctuation">}</span><span class="punctuation">;</span>
+<span class="keyword">mod</span> <span class="module declaration">inner</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="comment">// Needed for function consuming vs normal</span>
+<span class="keyword">pub</span> <span class="keyword">mod</span> <span class="module declaration">marker</span> <span class="punctuation">{</span>
+    <span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">lang</span><span class="attribute"> </span><span class="operator">=</span><span class="attribute"> </span><span class="string_literal">"copy"</span><span class="attribute">]</span>
+    <span class="keyword">pub</span> <span class="keyword">trait</span> <span class="trait declaration">Copy</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="attribute">]</span>
+<span class="keyword">struct</span> <span class="struct declaration">Foo</span> <span class="punctuation">{</span>
+    <span class="keyword">pub</span> <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
+    <span class="keyword">pub</span> <span class="field declaration">y</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">trait</span> <span class="trait declaration">Bar</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">bar</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="trait">Bar</span> <span class="keyword">for</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">bar</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+        <span class="self_keyword mutable">self</span><span class="punctuation">.</span><span class="field">x</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">quop</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Copy</span><span class="punctuation">,</span><span class="attribute"> Clone</span><span class="punctuation">)</span><span class="attribute">]</span>
+<span class="keyword">struct</span> <span class="struct declaration">FooCopy</span> <span class="punctuation">{</span>
+    <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">u32</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="struct">FooCopy</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+        <span class="self_keyword mutable">self</span><span class="punctuation">.</span><span class="field">x</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword">fn</span> <span class="function declaration">quop</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="self_keyword">self</span><span class="punctuation">.</span><span class="field">x</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable unsafe">STATIC_MUT</span><span class="punctuation">:</span> <span class="builtin_type">i32</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
+
+<span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">&lt;</span><span class="lifetime declaration">'a</span><span class="punctuation">,</span> <span class="type_param declaration">T</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="type_param">T</span> <span class="punctuation">{</span>
+    <span class="function">foo</span><span class="operator">::</span><span class="punctuation">&lt;</span><span class="lifetime">'a</span><span class="punctuation">,</span> <span class="builtin_type">i32</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span>
+<span class="punctuation">}</span>
+
+<span class="macro">macro_rules!</span> <span class="macro declaration">def_fn</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="macro">def_fn!</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">bar</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-</span><span class="operator">&gt;</span> <span class="builtin_type">u32</span> <span class="punctuation">{</span>
+        <span class="numeric_literal">100</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="macro">macro_rules!</span> <span class="macro declaration">noop</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span>expr<span class="punctuation">:</span>expr<span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
+        <span class="punctuation">$</span>expr
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="comment">// comment</span>
+<span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello, {}!"</span><span class="punctuation">,</span> <span class="numeric_literal">92</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">vec</span> <span class="operator">=</span> <span class="unresolved_reference">Vec</span><span class="operator">::</span><span class="unresolved_reference">new</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="keyword control">if</span> <span class="bool_literal">true</span> <span class="punctuation">{</span>
+        <span class="keyword">let</span> <span class="variable declaration">x</span> <span class="operator">=</span> <span class="numeric_literal">92</span><span class="punctuation">;</span>
+        <span class="variable mutable">vec</span><span class="punctuation">.</span><span class="unresolved_reference">push</span><span class="punctuation">(</span><span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">,</span> <span class="field">y</span><span class="punctuation">:</span> <span class="numeric_literal">1</span> <span class="punctuation">}</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+    <span class="keyword unsafe">unsafe</span> <span class="punctuation">{</span>
+        <span class="variable mutable">vec</span><span class="punctuation">.</span><span class="unresolved_reference">set_len</span><span class="punctuation">(</span><span class="numeric_literal">0</span><span class="punctuation">)</span><span class="punctuation">;</span>
+        <span class="static mutable unsafe">STATIC_MUT</span> <span class="operator">=</span> <span class="numeric_literal">1</span><span class="punctuation">;</span>
+    <span class="punctuation">}</span>
+
+    <span class="keyword control">for</span> <span class="variable declaration">e</span> <span class="keyword control">in</span> <span class="variable mutable">vec</span> <span class="punctuation">{</span>
+        <span class="comment">// Do nothing</span>
+    <span class="punctuation">}</span>
+
+    <span class="macro">noop!</span><span class="punctuation">(</span><span class="macro">noop</span><span class="macro">!</span><span class="punctuation">(</span><span class="numeric_literal">1</span><span class="punctuation">)</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">x</span> <span class="operator">=</span> <span class="numeric_literal">42</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration mutable">y</span> <span class="operator">=</span> <span class="operator">&</span><span class="keyword">mut</span> <span class="variable mutable">x</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration">z</span> <span class="operator">=</span> <span class="operator">&</span><span class="variable mutable">y</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">:</span> <span class="variable declaration">z</span><span class="punctuation">,</span> <span class="field">y</span> <span class="punctuation">}</span> <span class="operator">=</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">:</span> <span class="variable">z</span><span class="punctuation">,</span> <span class="field">y</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+
+    <span class="variable">y</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">foo</span> <span class="operator">=</span> <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">x</span><span class="punctuation">,</span> <span class="field">y</span><span class="punctuation">:</span> <span class="variable mutable">x</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function">quop</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function mutable">qux</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">foo</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable">copy</span> <span class="operator">=</span> <span class="struct">FooCopy</span> <span class="punctuation">{</span> <span class="field">x</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function">quop</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function mutable">qux</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="variable mutable">copy</span><span class="punctuation">.</span><span class="function">baz</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">enum</span> <span class="enum declaration">Option</span><span class="punctuation">&lt;</span><span class="type_param declaration">T</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
+    <span class="enum_variant declaration">Some</span><span class="punctuation">(</span><span class="type_param">T</span><span class="punctuation">)</span><span class="punctuation">,</span>
+    <span class="enum_variant declaration">None</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+<span class="keyword">use</span> <span class="enum">Option</span><span class="operator">::</span><span class="punctuation">*</span><span class="punctuation">;</span>
+
+<span class="keyword">impl</span><span class="punctuation">&lt;</span><span class="type_param declaration">T</span><span class="punctuation">&gt;</span> <span class="enum">Option</span><span class="punctuation">&lt;</span><span class="type_param">T</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration">and</span><span class="punctuation">&lt;</span><span class="type_param declaration">U</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="self_keyword">self</span><span class="punctuation">,</span> <span class="value_param declaration">other</span><span class="punctuation">:</span> <span class="enum">Option</span><span class="punctuation">&lt;</span><span class="type_param">U</span><span class="punctuation">&gt;</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="enum">Option</span><span class="punctuation">&lt;</span><span class="punctuation">(</span><span class="type_param">T</span><span class="punctuation">,</span> <span class="type_param">U</span><span class="punctuation">)</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span>
+        <span class="keyword control">match</span> <span class="value_param">other</span> <span class="punctuation">{</span>
+            <span class="enum_variant">None</span> <span class="operator">=&gt;</span> <span class="macro">unimplemented!</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">,</span>
+            <span class="variable declaration">Nope</span> <span class="operator">=&gt;</span> <span class="variable">Nope</span><span class="punctuation">,</span>
+        <span class="punctuation">}</span>
+    <span class="punctuation">}</span>
+<span class="punctuation">}</span></code></pre>
\ No newline at end of file
diff --git a/crates/ide/test_data/rainbow_highlighting.html b/crates/ide/test_data/rainbow_highlighting.html
new file mode 100644
index 000000000..401e87a73
--- /dev/null
+++ b/crates/ide/test_data/rainbow_highlighting.html
@@ -0,0 +1,49 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="2705725358298919760" style="color: hsl(76,47%,83%);">x</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="3365759661443752373" style="color: hsl(15,86%,51%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="794745962933817518" style="color: hsl(127,71%,87%);">x</span> <span class="operator">=</span> <span class="string_literal">"other color please!"</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration" data-binding-hash="6717528807933952652" style="color: hsl(90,74%,79%);">y</span> <span class="operator">=</span> <span class="variable" data-binding-hash="794745962933817518" style="color: hsl(127,71%,87%);">x</span><span class="punctuation">.</span><span class="unresolved_reference">to_string</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">fn</span> <span class="function declaration">bar</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+    <span class="keyword">let</span> <span class="keyword">mut</span> <span class="variable declaration mutable" data-binding-hash="8121853618659664005" style="color: hsl(273,88%,88%);">hello</span> <span class="operator">=</span> <span class="string_literal">"hello"</span><span class="punctuation">;</span>
+<span class="punctuation">}</span></code></pre>
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