78 files changed, 1606 insertions, 730 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 051d9e734..d8838cf2b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -253,7 +253,6 @@ dependencies = [
 name = "completion"
 version = "0.0.0"
 dependencies = [
- "assists",
  "base_db",
  "either",
  "expect-test",
@@ -301,7 +300,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dca26ee1f8d361640700bde38b2c37d8c22b3ce2d360e1fc1c74ea4b0aa7d775"
 dependencies = [
  "cfg-if 1.0.0",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
 ]
 
 [[package]]
@@ -312,18 +311,18 @@ checksum = "94af6efb46fef72616855b036a624cf27ba656ffc9be1b9a3c931cfc7749a9a9"
 dependencies = [
  "cfg-if 1.0.0",
  "crossbeam-epoch",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
 ]
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.9.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec0f606a85340376eef0d6d8fec399e6d4a544d648386c6645eb6d0653b27d9f"
+checksum = "a1aaa739f95311c2c7887a76863f500026092fb1dce0161dab577e559ef3569d"
 dependencies = [
  "cfg-if 1.0.0",
  "const_fn",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "lazy_static",
  "memoffset",
  "scopeguard",
@@ -342,13 +341,12 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.0"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec91540d98355f690a86367e566ecad2e9e579f230230eb7c21398372be73ea5"
+checksum = "02d96d1e189ef58269ebe5b97953da3274d83a93af647c2ddd6f9dab28cedb8d"
 dependencies = [
  "autocfg",
  "cfg-if 1.0.0",
- "const_fn",
  "lazy_static",
 ]
 
@@ -682,6 +680,7 @@ dependencies = [
  "expect-test",
  "fst",
  "hir",
+ "itertools",
  "log",
  "once_cell",
  "profile",
@@ -865,9 +864,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-types"
-version = "0.84.0"
+version = "0.85.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b95be71fe205e44de754185bcf86447b65813ce1ceb298f8d3793ade5fff08d"
+checksum = "857650f3e83fb62f89d15410414e0ed7d0735445020da398d37f65d20a5423b9"
 dependencies = [
  "base64",
  "bitflags",
@@ -929,9 +928,9 @@ dependencies = [
 
 [[package]]
 name = "memoffset"
-version = "0.5.6"
+version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "043175f069eda7b85febe4a74abbaeff828d9f8b448515d3151a14a3542811aa"
+checksum = "157b4208e3059a8f9e78d559edc658e13df41410cb3ae03979c83130067fdd87"
 dependencies = [
  "autocfg",
 ]
@@ -988,9 +987,9 @@ dependencies = [
 
 [[package]]
 name = "miow"
-version = "0.2.1"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
+checksum = "ebd808424166322d4a38da87083bfddd3ac4c131334ed55856112eb06d46944d"
 dependencies = [
  "kernel32-sys",
  "net2",
@@ -1000,9 +999,9 @@ dependencies = [
 
 [[package]]
 name = "net2"
-version = "0.2.35"
+version = "0.2.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ebc3ec692ed7c9a255596c67808dee269f64655d8baf7b4f0638e51ba1d6853"
+checksum = "d7cf75f38f16cb05ea017784dc6dbfd354f76c223dba37701734c4f5a9337d02"
 dependencies = [
  "cfg-if 0.1.10",
  "libc",
@@ -1298,7 +1297,7 @@ checksum = "9ab346ac5921dc62ffa9f89b7a773907511cdfa5490c572ae9be1be33e8afa4a"
 dependencies = [
  "crossbeam-channel 0.5.0",
  "crossbeam-deque",
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "lazy_static",
  "num_cpus",
 ]
@@ -1396,9 +1395,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-ap-rustc_lexer"
-version = "688.0.0"
+version = "691.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ebbdcc99bd015349093fcbae4780fda21416fec5d8843acfb3d1733e130cd4db"
+checksum = "44bc89d9ca7a78fb82e103b389362c55f03800745f8ba14e068b805cfaf783ec"
 dependencies = [
  "unicode-xid",
 ]
@@ -1436,7 +1435,7 @@ version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8fadca2ab5de17acf66d744f4888049ca8f1bb9b8a1ab8afd9d032cc959c5dc"
 dependencies = [
- "crossbeam-utils 0.8.0",
+ "crossbeam-utils 0.8.1",
  "indexmap",
  "lock_api",
  "log",
@@ -1627,9 +1626,9 @@ version = "0.0.0"
 
 [[package]]
 name = "syn"
-version = "1.0.51"
+version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b4f34193997d92804d359ed09953e25d5138df6bcc055a71bf68ee89fdf9223"
+checksum = "8833e20724c24de12bbaba5ad230ea61c3eafb05b881c7c9d3cfe8638b187e68"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -1658,6 +1657,7 @@ dependencies = [
  "itertools",
  "once_cell",
  "parser",
+ "profile",
  "rayon",
  "rowan",
  "rustc-ap-rustc_lexer",
@@ -1898,9 +1898,9 @@ dependencies = [
 
 [[package]]
 name = "unicode-segmentation"
-version = "1.7.0"
+version = "1.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db8716a166f290ff49dabc18b44aa407cb7c6dbe1aa0971b44b8a24b0ca35aae"
+checksum = "bb0d2e7be6ae3a5fa87eed5fb451aff96f2573d2694942e40543ae0bbe19c796"
 
 [[package]]
 name = "unicode-xid"
diff --git a/crates/assists/Cargo.toml b/crates/assists/Cargo.toml
index 108f656e9..3fd8327d6 100644
--- a/crates/assists/Cargo.toml
+++ b/crates/assists/Cargo.toml
@@ -12,7 +12,7 @@ doctest = false
 [dependencies]
 rustc-hash = "1.1.0"
 itertools = "0.9.0"
-either = "1.5.3"
+either = "1.6.1"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/assists/src/assist_config.rs b/crates/assists/src/assist_config.rs
index b24527ec4..786224cfa 100644
--- a/crates/assists/src/assist_config.rs
+++ b/crates/assists/src/assist_config.rs
@@ -5,8 +5,9 @@
 //! assists if we are allowed to.
 
 use hir::PrefixKind;
+use ide_db::helpers::insert_use::MergeBehaviour;
 
-use crate::{utils::MergeBehaviour, AssistKind};
+use crate::AssistKind;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct AssistConfig {
diff --git a/crates/assists/src/ast_transform.rs b/crates/assists/src/ast_transform.rs
index ac72f3f02..66e4634b1 100644
--- a/crates/assists/src/ast_transform.rs
+++ b/crates/assists/src/ast_transform.rs
@@ -1,5 +1,6 @@
 //! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
 use hir::{HirDisplay, PathResolution, SemanticsScope};
+use ide_db::helpers::mod_path_to_ast;
 use rustc_hash::FxHashMap;
 use syntax::{
     algo::SyntaxRewriter,
@@ -7,8 +8,6 @@ use syntax::{
     SyntaxNode,
 };
 
-use crate::utils::mod_path_to_ast;
-
 pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: N) -> N {
     SyntaxRewriter::from_fn(|element| match element {
         syntax::SyntaxElement::Node(n) => {
diff --git a/crates/assists/src/handlers/auto_import.rs b/crates/assists/src/handlers/auto_import.rs
index d665837a2..bd5bba646 100644
--- a/crates/assists/src/handlers/auto_import.rs
+++ b/crates/assists/src/handlers/auto_import.rs
@@ -1,8 +1,11 @@
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use syntax::ast;
 
 use crate::{
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::{insert_use, mod_path_to_ast, ImportScope},
     AssistContext, AssistId, AssistKind, Assists, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
index cac77c49b..d85767b4e 100644
--- a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -2,6 +2,10 @@ use std::iter;
 
 use either::Either;
 use hir::{AsName, EnumVariant, Module, ModuleDef, Name};
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use ide_db::{defs::Definition, search::Reference, RootDatabase};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
@@ -10,10 +14,7 @@ use syntax::{
     SourceFile, SyntaxElement, SyntaxNode, T,
 };
 
-use crate::{
-    utils::{insert_use, mod_path_to_ast, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: extract_struct_from_enum_variant
 //
@@ -236,10 +237,9 @@ fn update_reference(
 
 #[cfg(test)]
 mod tests {
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable},
-        utils::FamousDefs,
-    };
+    use ide_db::helpers::FamousDefs;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index eda45f5b3..ef12ef0cf 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -1,13 +1,14 @@
 use std::iter;
 
 use hir::{Adt, HasSource, ModuleDef, Semantics};
+use ide_db::helpers::{mod_path_to_ast, FamousDefs};
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 use test_utils::mark;
 
 use crate::{
-    utils::{mod_path_to_ast, render_snippet, Cursor, FamousDefs},
+    utils::{render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
@@ -212,12 +213,10 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> O
 
 #[cfg(test)]
 mod tests {
+    use ide_db::helpers::FamousDefs;
     use test_utils::mark;
 
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable, check_assist_target},
-        utils::FamousDefs,
-    };
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::fill_match_arms;
 
diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index 674e5a175..3c374e5d9 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -1,8 +1,9 @@
+use ide_db::helpers::FamousDefs;
 use ide_db::RootDatabase;
 use syntax::ast::{self, AstNode, NameOwner};
 use test_utils::mark;
 
-use crate::{utils::FamousDefs, AssistContext, AssistId, AssistKind, Assists};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_from_impl_for_enum
 //
diff --git a/crates/assists/src/handlers/infer_function_return_type.rs b/crates/assists/src/handlers/infer_function_return_type.rs
index 520d07ae0..aa584eb03 100644
--- a/crates/assists/src/handlers/infer_function_return_type.rs
+++ b/crates/assists/src/handlers/infer_function_return_type.rs
@@ -17,7 +17,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // fn foo() -> i32 { 42i32 }
 // ```
 pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
-    let (tail_expr, builder_edit_pos, wrap_expr) = extract_tail(ctx)?;
+    let (fn_type, tail_expr, builder_edit_pos) = extract_tail(ctx)?;
     let module = ctx.sema.scope(tail_expr.syntax()).module()?;
     let ty = ctx.sema.type_of_expr(&tail_expr)?;
     if ty.is_unit() {
@@ -27,7 +27,10 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext)
 
     acc.add(
         AssistId("infer_function_return_type", AssistKind::RefactorRewrite),
-        "Add this function's return type",
+        match fn_type {
+            FnType::Function => "Add this function's return type",
+            FnType::Closure { .. } => "Add this closure's return type",
+        },
         tail_expr.syntax().text_range(),
         |builder| {
             match builder_edit_pos {
@@ -38,7 +41,7 @@ pub(crate) fn infer_function_return_type(acc: &mut Assists, ctx: &AssistContext)
                     builder.replace(text_range, &format!("-> {}", ty))
                 }
             }
-            if wrap_expr {
+            if let FnType::Closure { wrap_expr: true } = fn_type {
                 mark::hit!(wrap_closure_non_block_expr);
                 // `|x| x` becomes `|x| -> T x` which is invalid, so wrap it in a block
                 builder.replace(tail_expr.syntax().text_range(), &format!("{{{}}}", tail_expr));
@@ -72,8 +75,13 @@ fn ret_ty_to_action(ret_ty: Option<ast::RetType>, insert_pos: TextSize) -> Optio
     }
 }
 
-fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool)> {
-    let (tail_expr, return_type_range, action, wrap_expr) =
+enum FnType {
+    Function,
+    Closure { wrap_expr: bool },
+}
+
+fn extract_tail(ctx: &AssistContext) -> Option<(FnType, ast::Expr, InsertOrReplace)> {
+    let (fn_type, tail_expr, return_type_range, action) =
         if let Some(closure) = ctx.find_node_at_offset::<ast::ClosureExpr>() {
             let rpipe_pos = closure.param_list()?.syntax().last_token()?.text_range().end();
             let action = ret_ty_to_action(closure.ret_type(), rpipe_pos)?;
@@ -86,7 +94,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
             };
 
             let ret_range = TextRange::new(rpipe_pos, body_start);
-            (tail_expr, ret_range, action, wrap_expr)
+            (FnType::Closure { wrap_expr }, tail_expr, ret_range, action)
         } else {
             let func = ctx.find_node_at_offset::<ast::Fn>()?;
             let rparen_pos = func.param_list()?.r_paren_token()?.text_range().end();
@@ -97,7 +105,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
 
             let ret_range_end = body.l_curly_token()?.text_range().start();
             let ret_range = TextRange::new(rparen_pos, ret_range_end);
-            (tail_expr, ret_range, action, false)
+            (FnType::Function, tail_expr, ret_range, action)
         };
     let frange = ctx.frange.range;
     if return_type_range.contains_range(frange) {
@@ -109,7 +117,7 @@ fn extract_tail(ctx: &AssistContext) -> Option<(ast::Expr, InsertOrReplace, bool
     } else {
         return None;
     }
-    Some((tail_expr, action, wrap_expr))
+    Some((fn_type, tail_expr, action))
 }
 
 #[cfg(test)]
diff --git a/crates/assists/src/handlers/merge_imports.rs b/crates/assists/src/handlers/merge_imports.rs
index fd9c9e03c..b7e853994 100644
--- a/crates/assists/src/handlers/merge_imports.rs
+++ b/crates/assists/src/handlers/merge_imports.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::insert_use::{try_merge_imports, try_merge_trees, MergeBehaviour};
 use syntax::{
     algo::{neighbor, SyntaxRewriter},
     ast, AstNode,
@@ -5,10 +6,7 @@ use syntax::{
 
 use crate::{
     assist_context::{AssistContext, Assists},
-    utils::{
-        insert_use::{try_merge_imports, try_merge_trees},
-        next_prev, MergeBehaviour,
-    },
+    utils::next_prev,
     AssistId, AssistKind,
 };
 
diff --git a/crates/assists/src/handlers/qualify_path.rs b/crates/assists/src/handlers/qualify_path.rs
index d5bc4e574..6f9810fe8 100644
--- a/crates/assists/src/handlers/qualify_path.rs
+++ b/crates/assists/src/handlers/qualify_path.rs
@@ -1,6 +1,7 @@
 use std::iter;
 
 use hir::AsName;
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::RootDatabase;
 use syntax::{
     ast,
@@ -12,7 +13,6 @@ use test_utils::mark;
 use crate::{
     assist_context::{AssistContext, Assists},
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::mod_path_to_ast,
     AssistId, AssistKind, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
index 453a6cebf..4d6a1956b 100644
--- a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::imports_locator;
 use itertools::Itertools;
 use syntax::{
@@ -10,8 +11,7 @@ use syntax::{
 use crate::{
     assist_context::{AssistBuilder, AssistContext, Assists},
     utils::{
-        add_trait_assoc_items_to_impl, filter_assoc_items, mod_path_to_ast, render_snippet, Cursor,
-        DefaultMethods,
+        add_trait_assoc_items_to_impl, filter_assoc_items, render_snippet, Cursor, DefaultMethods,
     },
     AssistId, AssistKind,
 };
diff --git a/crates/assists/src/handlers/replace_qualified_name_with_use.rs b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
index a66db9ae3..8193e45a8 100644
--- a/crates/assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
@@ -1,10 +1,8 @@
+use ide_db::helpers::insert_use::{insert_use, ImportScope};
 use syntax::{algo::SyntaxRewriter, ast, match_ast, AstNode, SyntaxNode};
 use test_utils::mark;
 
-use crate::{
-    utils::{insert_use, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: replace_qualified_name_with_use
 //
@@ -409,7 +407,7 @@ impl std::fmt::Display<|> for Foo {
 }
 ",
             r"
-use std::fmt::{nested::Debug, Display};
+use std::fmt::{Display, nested::Debug};
 
 impl Display for Foo {
 }
diff --git a/crates/assists/src/handlers/ignore_test.rs b/crates/assists/src/handlers/toggle_ignore.rs
index 5096a0005..14b420421 100644
--- a/crates/assists/src/handlers/ignore_test.rs
+++ b/crates/assists/src/handlers/toggle_ignore.rs
@@ -5,7 +5,7 @@ use syntax::{
 
 use crate::{utils::test_related_attribute, AssistContext, AssistId, AssistKind, Assists};
 
-// Assist: ignore_test
+// Assist: toggle_ignore
 //
 // Adds `#[ignore]` attribute to the test.
 //
@@ -23,20 +23,20 @@ use crate::{utils::test_related_attribute, AssistContext, AssistId, AssistKind,
 //     assert_eq!(2 + 2, 5);
 // }
 // ```
-pub(crate) fn ignore_test(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+pub(crate) fn toggle_ignore(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let attr: ast::Attr = ctx.find_node_at_offset()?;
     let func = attr.syntax().parent().and_then(ast::Fn::cast)?;
     let attr = test_related_attribute(&func)?;
 
     match has_ignore_attribute(&func) {
         None => acc.add(
-            AssistId("ignore_test", AssistKind::None),
+            AssistId("toggle_ignore", AssistKind::None),
             "Ignore this test",
             attr.syntax().text_range(),
             |builder| builder.insert(attr.syntax().text_range().end(), &format!("\n#[ignore]")),
         ),
         Some(ignore_attr) => acc.add(
-            AssistId("unignore_test", AssistKind::None),
+            AssistId("toggle_ignore", AssistKind::None),
             "Re-enable this test",
             ignore_attr.syntax().text_range(),
             |builder| {
@@ -55,24 +55,19 @@ pub(crate) fn ignore_test(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
 }
 
 fn has_ignore_attribute(fn_def: &ast::Fn) -> Option<ast::Attr> {
-    fn_def.attrs().find_map(|attr| {
-        if attr.path()?.syntax().text() == "ignore" {
-            Some(attr)
-        } else {
-            None
-        }
-    })
+    fn_def.attrs().find(|attr| attr.path().map(|it| it.syntax().text() == "ignore") == Some(true))
 }
 
 #[cfg(test)]
 mod tests {
-    use super::ignore_test;
     use crate::tests::check_assist;
 
+    use super::*;
+
     #[test]
     fn test_base_case() {
         check_assist(
-            ignore_test,
+            toggle_ignore,
             r#"
             #[test<|>]
             fn test() {}
@@ -88,7 +83,7 @@ mod tests {
     #[test]
     fn test_unignore() {
         check_assist(
-            ignore_test,
+            toggle_ignore,
             r#"
             #[test<|>]
             #[ignore]
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index 17e9312db..dfe6c2729 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -141,7 +141,6 @@ mod handlers {
     mod generate_function;
     mod generate_impl;
     mod generate_new;
-    mod ignore_test;
     mod infer_function_return_type;
     mod inline_local_variable;
     mod introduce_named_lifetime;
@@ -164,6 +163,7 @@ mod handlers {
     mod replace_string_with_char;
     mod replace_unwrap_with_match;
     mod split_import;
+    mod toggle_ignore;
     mod unwrap_block;
     mod wrap_return_type_in_result;
 
@@ -190,7 +190,6 @@ mod handlers {
             generate_function::generate_function,
             generate_impl::generate_impl,
             generate_new::generate_new,
-            ignore_test::ignore_test,
             infer_function_return_type::infer_function_return_type,
             inline_local_variable::inline_local_variable,
             introduce_named_lifetime::introduce_named_lifetime,
@@ -215,6 +214,7 @@ mod handlers {
             replace_qualified_name_with_use::replace_qualified_name_with_use,
             replace_unwrap_with_match::replace_unwrap_with_match,
             split_import::split_import,
+            toggle_ignore::toggle_ignore,
             unwrap_block::unwrap_block,
             wrap_return_type_in_result::wrap_return_type_in_result,
             // These are manually sorted for better priorities
diff --git a/crates/assists/src/tests/generated.rs b/crates/assists/src/tests/generated.rs
index 5a9d1a01b..8d50c8791 100644
--- a/crates/assists/src/tests/generated.rs
+++ b/crates/assists/src/tests/generated.rs
@@ -474,26 +474,6 @@ impl<T: Clone> Ctx<T> {
 }
 
 #[test]
-fn doctest_ignore_test() {
-    check_doc_test(
-        "ignore_test",
-        r#####"
-<|>#[test]
-fn arithmetics {
-    assert_eq!(2 + 2, 5);
-}
-"#####,
-        r#####"
-#[test]
-#[ignore]
-fn arithmetics {
-    assert_eq!(2 + 2, 5);
-}
-"#####,
-    )
-}
-
-#[test]
 fn doctest_infer_function_return_type() {
     check_doc_test(
         "infer_function_return_type",
@@ -979,6 +959,26 @@ use std::{collections::HashMap};
 }
 
 #[test]
+fn doctest_toggle_ignore() {
+    check_doc_test(
+        "toggle_ignore",
+        r#####"
+<|>#[test]
+fn arithmetics {
+    assert_eq!(2 + 2, 5);
+}
+"#####,
+        r#####"
+#[test]
+#[ignore]
+fn arithmetics {
+    assert_eq!(2 + 2, 5);
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_unwrap_block() {
     check_doc_test(
         "unwrap_block",
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 66c0cdd5f..01f5c291f 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -1,10 +1,9 @@
 //! Assorted functions shared by several assists.
-pub(crate) mod insert_use;
 pub(crate) mod import_assets;
 
 use std::ops;
 
-use hir::{Crate, Enum, HasSource, Module, ScopeDef, Semantics, Trait};
+use hir::HasSource;
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::{
@@ -22,29 +21,6 @@ use crate::{
     ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
 };
 
-pub use insert_use::{insert_use, ImportScope, MergeBehaviour};
-
-pub fn mod_path_to_ast(path: &hir::ModPath) -> ast::Path {
-    let mut segments = Vec::new();
-    let mut is_abs = false;
-    match path.kind {
-        hir::PathKind::Plain => {}
-        hir::PathKind::Super(0) => segments.push(make::path_segment_self()),
-        hir::PathKind::Super(n) => segments.extend((0..n).map(|_| make::path_segment_super())),
-        hir::PathKind::DollarCrate(_) | hir::PathKind::Crate => {
-            segments.push(make::path_segment_crate())
-        }
-        hir::PathKind::Abs => is_abs = true,
-    }
-
-    segments.extend(
-        path.segments
-            .iter()
-            .map(|segment| make::path_segment(make::name_ref(&segment.to_string()))),
-    );
-    make::path_from_segments(segments, is_abs)
-}
-
 pub(crate) fn unwrap_trivial_block(block: ast::BlockExpr) -> ast::Expr {
     extract_trivial_expression(&block)
         .filter(|expr| !expr.syntax().text().contains_char('\n'))
@@ -259,179 +235,6 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
     }
 }
 
-/// Helps with finding well-know things inside the standard library. This is
-/// somewhat similar to the known paths infra inside hir, but it different; We
-/// want to make sure that IDE specific paths don't become interesting inside
-/// the compiler itself as well.
-pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Crate>);
-
-#[allow(non_snake_case)]
-impl FamousDefs<'_, '_> {
-    pub const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
-pub mod convert {
-    pub trait From<T> {
-        fn from(t: T) -> Self;
-    }
-}
-
-pub mod default {
-    pub trait Default {
-       fn default() -> Self;
-    }
-}
-
-pub mod iter {
-    pub use self::traits::{collect::IntoIterator, iterator::Iterator};
-    mod traits {
-        pub(crate) mod iterator {
-            use crate::option::Option;
-            pub trait Iterator {
-                type Item;
-                fn next(&mut self) -> Option<Self::Item>;
-                fn by_ref(&mut self) -> &mut Self {
-                    self
-                }
-                fn take(self, n: usize) -> crate::iter::Take<Self> {
-                    crate::iter::Take { inner: self }
-                }
-            }
-
-            impl<I: Iterator> Iterator for &mut I {
-                type Item = I::Item;
-                fn next(&mut self) -> Option<I::Item> {
-                    (**self).next()
-                }
-            }
-        }
-        pub(crate) mod collect {
-            pub trait IntoIterator {
-                type Item;
-            }
-        }
-    }
-
-    pub use self::sources::*;
-    pub(crate) mod sources {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Repeat<A> {
-            element: A,
-        }
-
-        pub fn repeat<T>(elt: T) -> Repeat<T> {
-            Repeat { element: elt }
-        }
-
-        impl<A> Iterator for Repeat<A> {
-            type Item = A;
-
-            fn next(&mut self) -> Option<A> {
-                None
-            }
-        }
-    }
-
-    pub use self::adapters::*;
-    pub(crate) mod adapters {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Take<I> { pub(crate) inner: I }
-        impl<I> Iterator for Take<I> where I: Iterator {
-            type Item = <I as Iterator>::Item;
-            fn next(&mut self) -> Option<<I as Iterator>::Item> {
-                None
-            }
-        }
-    }
-}
-
-pub mod option {
-    pub enum Option<T> { None, Some(T)}
-}
-
-pub mod prelude {
-    pub use crate::{convert::From, iter::{IntoIterator, Iterator}, option::Option::{self, *}, default::Default};
-}
-#[prelude_import]
-pub use prelude::*;
-"#;
-
-    pub fn core(&self) -> Option<Crate> {
-        self.find_crate("core")
-    }
-
-    pub(crate) fn core_convert_From(&self) -> Option<Trait> {
-        self.find_trait("core:convert:From")
-    }
-
-    pub(crate) fn core_option_Option(&self) -> Option<Enum> {
-        self.find_enum("core:option:Option")
-    }
-
-    pub fn core_default_Default(&self) -> Option<Trait> {
-        self.find_trait("core:default:Default")
-    }
-
-    pub fn core_iter_Iterator(&self) -> Option<Trait> {
-        self.find_trait("core:iter:traits:iterator:Iterator")
-    }
-
-    pub fn core_iter(&self) -> Option<Module> {
-        self.find_module("core:iter")
-    }
-
-    fn find_trait(&self, path: &str) -> Option<Trait> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_enum(&self, path: &str) -> Option<Enum> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Adt(hir::Adt::Enum(it))) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_module(&self, path: &str) -> Option<Module> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_crate(&self, name: &str) -> Option<Crate> {
-        let krate = self.1?;
-        let db = self.0.db;
-        let res =
-            krate.dependencies(db).into_iter().find(|dep| dep.name.to_string() == name)?.krate;
-        Some(res)
-    }
-
-    fn find_def(&self, path: &str) -> Option<ScopeDef> {
-        let db = self.0.db;
-        let mut path = path.split(':');
-        let trait_ = path.next_back()?;
-        let std_crate = path.next()?;
-        let std_crate = self.find_crate(std_crate)?;
-        let mut module = std_crate.root_module(db);
-        for segment in path {
-            module = module.children(db).find_map(|child| {
-                let name = child.name(db)?;
-                if name.to_string() == segment {
-                    Some(child)
-                } else {
-                    None
-                }
-            })?;
-        }
-        let def =
-            module.scope(db, None).into_iter().find(|(name, _def)| name.to_string() == trait_)?.1;
-        Some(def)
-    }
-}
-
 pub(crate) fn next_prev() -> impl Iterator<Item = Direction> {
     [Direction::Next, Direction::Prev].iter().copied()
 }
diff --git a/crates/completion/Cargo.toml b/crates/completion/Cargo.toml
index e7df9d955..35e169a28 100644
--- a/crates/completion/Cargo.toml
+++ b/crates/completion/Cargo.toml
@@ -15,7 +15,6 @@ log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.6.1"
 
-assists = { path = "../assists", version = "0.0.0" }
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
 text_edit = { path = "../text_edit", version = "0.0.0" }
diff --git a/crates/completion/src/completions/postfix.rs b/crates/completion/src/completions/postfix.rs
index 7fbda7a6b..c8ba63cd3 100644
--- a/crates/completion/src/completions/postfix.rs
+++ b/crates/completion/src/completions/postfix.rs
@@ -5,6 +5,7 @@ mod format_like;
 use ide_db::ty_filter::TryEnum;
 use syntax::{
     ast::{self, AstNode, AstToken},
+    SyntaxKind::{BLOCK_EXPR, EXPR_STMT},
     TextRange, TextSize,
 };
 use text_edit::TextEdit;
@@ -220,6 +221,29 @@ pub(crate) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
     )
     .add_to(acc);
 
+    if let Some(parent) = dot_receiver.syntax().parent().and_then(|p| p.parent()) {
+        if matches!(parent.kind(), BLOCK_EXPR | EXPR_STMT) {
+            postfix_snippet(
+                ctx,
+                cap,
+                &dot_receiver,
+                "let",
+                "let",
+                &format!("let $0 = {};", receiver_text),
+            )
+            .add_to(acc);
+            postfix_snippet(
+                ctx,
+                cap,
+                &dot_receiver,
+                "letm",
+                "let mut",
+                &format!("let mut $0 = {};", receiver_text),
+            )
+            .add_to(acc);
+        }
+    }
+
     if let ast::Expr::Literal(literal) = dot_receiver.clone() {
         if let Some(literal_text) = ast::String::cast(literal.token()) {
             add_format_like_completions(acc, ctx, &dot_receiver, cap, &literal_text);
@@ -296,6 +320,38 @@ fn main() {
                 sn dbg   dbg!(expr)
                 sn dbgr  dbg!(&expr)
                 sn if    if expr {}
+                sn let   let
+                sn letm  let mut
+                sn match match expr {}
+                sn not   !expr
+                sn ok    Ok(expr)
+                sn ref   &expr
+                sn refm  &mut expr
+                sn some  Some(expr)
+                sn while while expr {}
+            "#]],
+        );
+    }
+
+    #[test]
+    fn postfix_completion_works_for_function_calln() {
+        check(
+            r#"
+fn foo(elt: bool) -> bool {
+    !elt
+}
+
+fn main() {
+    let bar = true;
+    foo(bar.<|>)
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn dbgr  dbg!(&expr)
+                sn if    if expr {}
                 sn match match expr {}
                 sn not   !expr
                 sn ok    Ok(expr)
@@ -321,6 +377,8 @@ fn main() {
                 sn call  function(expr)
                 sn dbg   dbg!(expr)
                 sn dbgr  dbg!(&expr)
+                sn let   let
+                sn letm  let mut
                 sn match match expr {}
                 sn ok    Ok(expr)
                 sn ref   &expr
@@ -331,6 +389,34 @@ fn main() {
     }
 
     #[test]
+    fn let_middle_block() {
+        check(
+            r#"
+fn main() {
+    baz.l<|>
+    res
+}
+"#,
+            expect![[r#"
+                sn box   Box::new(expr)
+                sn call  function(expr)
+                sn dbg   dbg!(expr)
+                sn dbgr  dbg!(&expr)
+                sn if    if expr {}
+                sn let   let
+                sn letm  let mut
+                sn match match expr {}
+                sn not   !expr
+                sn ok    Ok(expr)
+                sn ref   &expr
+                sn refm  &mut expr
+                sn some  Some(expr)
+                sn while while expr {}
+            "#]],
+        );
+    }
+
+    #[test]
     fn option_iflet() {
         check_edit(
             "ifl",
diff --git a/crates/completion/src/completions/qualified_path.rs b/crates/completion/src/completions/qualified_path.rs
index d9387054d..bc23bea3f 100644
--- a/crates/completion/src/completions/qualified_path.rs
+++ b/crates/completion/src/completions/qualified_path.rs
@@ -353,10 +353,10 @@ impl S {
 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)
+                ct C    const C: i32 = 42;
+                ta T    type T = i32;
+                fn a()  fn a()
+                me b(…) fn b(&self)
             "#]],
         );
     }
@@ -503,14 +503,14 @@ trait Sub: Super {
 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)
+                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)
             "#]],
         );
     }
@@ -543,14 +543,14 @@ impl<T> Sub for Wrap<T> {
 }
 "#,
             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)
+                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)
             "#]],
         );
     }
diff --git a/crates/completion/src/completions/record.rs b/crates/completion/src/completions/record.rs
index 2049b9d09..eaa44c97d 100644
--- a/crates/completion/src/completions/record.rs
+++ b/crates/completion/src/completions/record.rs
@@ -1,5 +1,5 @@
 //! Complete fields in record literals and patterns.
-use assists::utils::FamousDefs;
+use ide_db::helpers::FamousDefs;
 use syntax::ast::Expr;
 
 use crate::{
@@ -45,8 +45,8 @@ pub(crate) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) ->
 
 #[cfg(test)]
 mod tests {
-    use assists::utils::FamousDefs;
     use expect_test::{expect, Expect};
+    use ide_db::helpers::FamousDefs;
 
     use crate::{test_utils::completion_list, CompletionKind};
 
diff --git a/crates/completion/src/completions/trait_impl.rs b/crates/completion/src/completions/trait_impl.rs
index a14be9c73..e2fe44aff 100644
--- a/crates/completion/src/completions/trait_impl.rs
+++ b/crates/completion/src/completions/trait_impl.rs
@@ -139,7 +139,7 @@ fn add_function_impl(
 ) {
     let fn_name = func.name(ctx.db).to_string();
 
-    let label = if func.params(ctx.db).is_empty() {
+    let label = if func.assoc_fn_params(ctx.db).is_empty() {
         format!("fn {}()", fn_name)
     } else {
         format!("fn {}(..)", fn_name)
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index 3bd776905..81691cd7f 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -1,8 +1,8 @@
 //! Completion of names from the current scope, e.g. locals and imported items.
 
-use assists::utils::ImportScope;
 use either::Either;
 use hir::{Adt, ModuleDef, ScopeDef, Type};
+use ide_db::helpers::insert_use::ImportScope;
 use ide_db::imports_locator;
 use syntax::AstNode;
 use test_utils::mark;
diff --git a/crates/completion/src/config.rs b/crates/completion/src/config.rs
index f50735372..654a76f7b 100644
--- a/crates/completion/src/config.rs
+++ b/crates/completion/src/config.rs
@@ -4,7 +4,7 @@
 //! module, and we use to statically check that we only produce snippet
 //! completions if we are allowed to.
 
-use assists::utils::MergeBehaviour;
+use ide_db::helpers::insert_use::MergeBehaviour;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct CompletionConfig {
diff --git a/crates/completion/src/item.rs b/crates/completion/src/item.rs
index b13c3f376..e85549fef 100644
--- a/crates/completion/src/item.rs
+++ b/crates/completion/src/item.rs
@@ -2,8 +2,11 @@
 
 use std::fmt;
 
-use assists::utils::{insert_use, mod_path_to_ast, ImportScope, MergeBehaviour};
 use hir::{Documentation, ModPath, Mutability};
+use ide_db::helpers::{
+    insert_use::{self, ImportScope, MergeBehaviour},
+    mod_path_to_ast,
+};
 use syntax::{algo, TextRange};
 use text_edit::TextEdit;
 
@@ -201,7 +204,7 @@ impl CompletionItem {
             trigger_call_info: None,
             score: None,
             ref_match: None,
-            import_data: None,
+            import_to_add: None,
         }
     }
 
@@ -255,13 +258,21 @@ impl CompletionItem {
     }
 }
 
+/// An extra import to add after the completion is applied.
+#[derive(Clone)]
+pub(crate) struct ImportToAdd {
+    pub(crate) import_path: ModPath,
+    pub(crate) import_scope: ImportScope,
+    pub(crate) merge_behaviour: Option<MergeBehaviour>,
+}
+
 /// A helper to make `CompletionItem`s.
 #[must_use]
 #[derive(Clone)]
 pub(crate) struct Builder {
     source_range: TextRange,
     completion_kind: CompletionKind,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     label: String,
     insert_text: Option<String>,
     insert_text_format: InsertTextFormat,
@@ -278,14 +289,16 @@ pub(crate) struct Builder {
 
 impl Builder {
     pub(crate) fn build(self) -> CompletionItem {
+        let _p = profile::span("item::Builder::build");
+
         let mut label = self.label;
         let mut lookup = self.lookup;
         let mut insert_text = self.insert_text;
         let mut text_edits = TextEdit::builder();
 
-        if let Some((import_path, import_scope, merge_behaviour)) = self.import_data {
-            let import = mod_path_to_ast(&import_path);
-            let mut import_path_without_last_segment = import_path;
+        if let Some(import_data) = self.import_to_add {
+            let import = mod_path_to_ast(&import_data.import_path);
+            let mut import_path_without_last_segment = import_data.import_path;
             let _ = import_path_without_last_segment.segments.pop();
 
             if !import_path_without_last_segment.segments.is_empty() {
@@ -298,7 +311,11 @@ impl Builder {
                 label = format!("{}::{}", import_path_without_last_segment, label);
             }
 
-            let rewriter = insert_use(&import_scope, import, merge_behaviour);
+            let rewriter = insert_use::insert_use(
+                &import_data.import_scope,
+                import,
+                import_data.merge_behaviour,
+            );
             if let Some(old_ast) = rewriter.rewrite_root() {
                 algo::diff(&old_ast, &rewriter.rewrite(&old_ast)).into_text_edit(&mut text_edits);
             }
@@ -390,11 +407,8 @@ impl Builder {
         self.trigger_call_info = Some(true);
         self
     }
-    pub(crate) fn import_data(
-        mut self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> Builder {
-        self.import_data = import_data;
+    pub(crate) fn add_import(mut self, import_to_add: Option<ImportToAdd>) -> Builder {
+        self.import_to_add = import_to_add;
         self
     }
     pub(crate) fn set_ref_match(
diff --git a/crates/completion/src/lib.rs b/crates/completion/src/lib.rs
index aecc1378b..1ec2e9be7 100644
--- a/crates/completion/src/lib.rs
+++ b/crates/completion/src/lib.rs
@@ -44,6 +44,8 @@ pub use crate::{
 // - `expr.while` -> `while expr {}` or `while let ... {}` for `Option` or `Result`
 // - `expr.ref` -> `&expr`
 // - `expr.refm` -> `&mut expr`
+// - `expr.let` -> `let <|> = expr;`
+// - `expr.letm` -> `let mut <|> = expr;`
 // - `expr.not` -> `!expr`
 // - `expr.dbg` -> `dbg!(expr)`
 // - `expr.dbgr` -> `dbg!(&expr)`
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index bce02f577..504757a6a 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -9,15 +9,15 @@ pub(crate) mod type_alias;
 
 mod builder_ext;
 
-use assists::utils::{ImportScope, MergeBehaviour};
 use hir::{Documentation, HasAttrs, HirDisplay, ModPath, Mutability, ScopeDef, Type};
+use ide_db::helpers::insert_use::{ImportScope, MergeBehaviour};
 use ide_db::RootDatabase;
 use syntax::TextRange;
 use test_utils::mark;
 
 use crate::{
-    config::SnippetCap, CompletionContext, CompletionItem, CompletionItemKind, CompletionKind,
-    CompletionScore,
+    config::SnippetCap, item::ImportToAdd, CompletionContext, CompletionItem, CompletionItemKind,
+    CompletionKind, CompletionScore,
 };
 
 use crate::render::{enum_variant::render_enum_variant, function::render_fn, macro_::render_macro};
@@ -48,15 +48,15 @@ pub(crate) fn render_resolution<'a>(
 
 pub(crate) fn render_resolution_with_import<'a>(
     ctx: RenderContext<'a>,
-    import: ModPath,
+    import_path: ModPath,
     import_scope: ImportScope,
     merge_behaviour: Option<MergeBehaviour>,
     resolution: &ScopeDef,
 ) -> Option<CompletionItem> {
-    let local_name = import.segments.last()?.to_string();
+    let local_name = import_path.segments.last()?.to_string();
     Render::new(ctx).render_resolution(
         local_name,
-        Some((import, import_scope, merge_behaviour)),
+        Some(ImportToAdd { import_path, import_scope, merge_behaviour }),
         resolution,
     )
 }
@@ -147,7 +147,7 @@ impl<'a> Render<'a> {
     fn render_resolution(
         self,
         local_name: String,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+        import_to_add: Option<ImportToAdd>,
         resolution: &ScopeDef,
     ) -> Option<CompletionItem> {
         let _p = profile::span("render_resolution");
@@ -160,15 +160,16 @@ impl<'a> Render<'a> {
 
         let kind = match resolution {
             ScopeDef::ModuleDef(Function(func)) => {
-                let item = render_fn(self.ctx, import_data, Some(local_name), *func);
+                let item = render_fn(self.ctx, import_to_add, Some(local_name), *func);
                 return Some(item);
             }
             ScopeDef::ModuleDef(EnumVariant(var)) => {
-                let item = render_enum_variant(self.ctx, import_data, Some(local_name), *var, None);
+                let item =
+                    render_enum_variant(self.ctx, import_to_add, Some(local_name), *var, None);
                 return Some(item);
             }
             ScopeDef::MacroDef(mac) => {
-                let item = render_macro(self.ctx, import_data, local_name, *mac);
+                let item = render_macro(self.ctx, import_to_add, local_name, *mac);
                 return item;
             }
 
@@ -193,7 +194,7 @@ impl<'a> Render<'a> {
                     local_name,
                 )
                 .kind(CompletionItemKind::UnresolvedReference)
-                .import_data(import_data)
+                .add_import(import_to_add)
                 .build();
                 return Some(item);
             }
@@ -248,7 +249,7 @@ impl<'a> Render<'a> {
 
         let item = item
             .kind(kind)
-            .import_data(import_data)
+            .add_import(import_to_add)
             .set_documentation(docs)
             .set_ref_match(ref_match)
             .build();
diff --git a/crates/completion/src/render/builder_ext.rs b/crates/completion/src/render/builder_ext.rs
index 37b0d0459..ce8718bd5 100644
--- a/crates/completion/src/render/builder_ext.rs
+++ b/crates/completion/src/render/builder_ext.rs
@@ -5,6 +5,7 @@ use test_utils::mark;
 
 use crate::{item::Builder, CompletionContext};
 
+#[derive(Debug)]
 pub(super) enum Params {
     Named(Vec<String>),
     Anonymous(usize),
@@ -24,7 +25,7 @@ impl Params {
 }
 
 impl Builder {
-    pub(super) fn should_add_parems(&self, ctx: &CompletionContext) -> bool {
+    fn should_add_parens(&self, ctx: &CompletionContext) -> bool {
         if !ctx.config.add_call_parenthesis {
             return false;
         }
@@ -58,7 +59,7 @@ impl Builder {
         name: String,
         params: Params,
     ) -> Builder {
-        if !self.should_add_parems(ctx) {
+        if !self.should_add_parens(ctx) {
             return self;
         }
 
diff --git a/crates/completion/src/render/enum_variant.rs b/crates/completion/src/render/enum_variant.rs
index 6070e9b1d..f4bd02f25 100644
--- a/crates/completion/src/render/enum_variant.rs
+++ b/crates/completion/src/render/enum_variant.rs
@@ -1,23 +1,23 @@
 //! Renderer for `enum` variants.
 
-use assists::utils::{ImportScope, MergeBehaviour};
 use hir::{HasAttrs, HirDisplay, ModPath, StructKind};
 use itertools::Itertools;
 use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::{builder_ext::Params, RenderContext},
 };
 
 pub(crate) fn render_enum_variant<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     local_name: Option<String>,
     variant: hir::EnumVariant,
     path: Option<ModPath>,
 ) -> CompletionItem {
-    EnumVariantRender::new(ctx, local_name, variant, path).render(import_data)
+    let _p = profile::span("render_enum_variant");
+    EnumVariantRender::new(ctx, local_name, variant, path).render(import_to_add)
 }
 
 #[derive(Debug)]
@@ -62,10 +62,7 @@ impl<'a> EnumVariantRender<'a> {
         }
     }
 
-    fn render(
-        self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> CompletionItem {
+    fn render(self, import_to_add: Option<ImportToAdd>) -> CompletionItem {
         let mut builder = CompletionItem::new(
             CompletionKind::Reference,
             self.ctx.source_range(),
@@ -74,7 +71,7 @@ impl<'a> EnumVariantRender<'a> {
         .kind(CompletionItemKind::EnumVariant)
         .set_documentation(self.variant.docs(self.ctx.db()))
         .set_deprecated(self.ctx.is_deprecated(self.variant))
-        .import_data(import_data)
+        .add_import(import_to_add)
         .detail(self.detail());
 
         if self.variant_kind == StructKind::Tuple {
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 9dd5cd18c..00e3eb203 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -1,28 +1,29 @@
 //! Renderer for function calls.
 
-use assists::utils::{ImportScope, MergeBehaviour};
-use hir::{HasSource, ModPath, Type};
+use hir::{HasSource, Type};
 use syntax::{ast::Fn, display::function_declaration};
+use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::{builder_ext::Params, RenderContext},
 };
 
 pub(crate) fn render_fn<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     local_name: Option<String>,
     fn_: hir::Function,
 ) -> CompletionItem {
-    FunctionRender::new(ctx, local_name, fn_).render(import_data)
+    let _p = profile::span("render_fn");
+    FunctionRender::new(ctx, local_name, fn_).render(import_to_add)
 }
 
 #[derive(Debug)]
 struct FunctionRender<'a> {
     ctx: RenderContext<'a>,
     name: String,
-    fn_: hir::Function,
+    func: hir::Function,
     ast_node: Fn,
 }
 
@@ -35,21 +36,18 @@ impl<'a> FunctionRender<'a> {
         let name = local_name.unwrap_or_else(|| fn_.name(ctx.db()).to_string());
         let ast_node = fn_.source(ctx.db()).value;
 
-        FunctionRender { ctx, name, fn_, ast_node }
+        FunctionRender { ctx, name, func: fn_, ast_node }
     }
 
-    fn render(
-        self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> CompletionItem {
+    fn render(self, import_to_add: Option<ImportToAdd>) -> CompletionItem {
         let params = self.params();
         CompletionItem::new(CompletionKind::Reference, self.ctx.source_range(), self.name.clone())
             .kind(self.kind())
-            .set_documentation(self.ctx.docs(self.fn_))
-            .set_deprecated(self.ctx.is_deprecated(self.fn_))
+            .set_documentation(self.ctx.docs(self.func))
+            .set_deprecated(self.ctx.is_deprecated(self.func))
             .detail(self.detail())
             .add_call_parens(self.ctx.completion, self.name, params)
-            .import_data(import_data)
+            .add_import(import_to_add)
             .build()
     }
 
@@ -70,27 +68,39 @@ impl<'a> FunctionRender<'a> {
     }
 
     fn params(&self) -> Params {
-        let params_ty = self.fn_.params(self.ctx.db());
-        let params = self
-            .ast_node
-            .param_list()
+        let ast_params = match self.ast_node.param_list() {
+            Some(it) => it,
+            None => return Params::Named(Vec::new()),
+        };
+
+        let mut params_pats = Vec::new();
+        let params_ty = if self.ctx.completion.dot_receiver.is_some() {
+            self.func.method_params(self.ctx.db()).unwrap_or_default()
+        } else {
+            if let Some(s) = ast_params.self_param() {
+                mark::hit!(parens_for_method_call_as_assoc_fn);
+                params_pats.push(Some(s.to_string()));
+            }
+            self.func.assoc_fn_params(self.ctx.db())
+        };
+        params_pats
+            .extend(ast_params.params().into_iter().map(|it| it.pat().map(|it| it.to_string())));
+
+        let params = params_pats
             .into_iter()
-            .flat_map(|it| it.params())
             .zip(params_ty)
-            .flat_map(|(it, param_ty)| {
-                if let Some(pat) = it.pat() {
-                    let name = pat.to_string();
-                    let arg = name.trim_start_matches("mut ").trim_start_matches('_');
-                    return Some(self.add_arg(arg, param_ty.ty()));
-                }
-                None
+            .flat_map(|(pat, param_ty)| {
+                let pat = pat?;
+                let name = pat.to_string();
+                let arg = name.trim_start_matches("mut ").trim_start_matches('_');
+                Some(self.add_arg(arg, param_ty.ty()))
             })
             .collect();
         Params::Named(params)
     }
 
     fn kind(&self) -> CompletionItemKind {
-        if self.fn_.self_param(self.ctx.db()).is_some() {
+        if self.func.self_param(self.ctx.db()).is_some() {
             CompletionItemKind::Method
         } else {
             CompletionItemKind::Function
@@ -176,6 +186,28 @@ fn bar(s: &S) {
     }
 
     #[test]
+    fn parens_for_method_call_as_assoc_fn() {
+        mark::check!(parens_for_method_call_as_assoc_fn);
+        check_edit(
+            "foo",
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::f<|> }
+"#,
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::foo(${1:&self})$0 }
+"#,
+        );
+    }
+
+    #[test]
     fn suppress_arg_snippets() {
         mark::check!(suppress_arg_snippets);
         check_edit_with_config(
diff --git a/crates/completion/src/render/macro_.rs b/crates/completion/src/render/macro_.rs
index fead59e41..b4ab32c6e 100644
--- a/crates/completion/src/render/macro_.rs
+++ b/crates/completion/src/render/macro_.rs
@@ -1,22 +1,22 @@
 //! Renderer for macro invocations.
 
-use assists::utils::{ImportScope, MergeBehaviour};
-use hir::{Documentation, HasSource, ModPath};
+use hir::{Documentation, HasSource};
 use syntax::display::macro_label;
 use test_utils::mark;
 
 use crate::{
-    item::{CompletionItem, CompletionItemKind, CompletionKind},
+    item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
     render::RenderContext,
 };
 
 pub(crate) fn render_macro<'a>(
     ctx: RenderContext<'a>,
-    import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
+    import_to_add: Option<ImportToAdd>,
     name: String,
     macro_: hir::MacroDef,
 ) -> Option<CompletionItem> {
-    MacroRender::new(ctx, name, macro_).render(import_data)
+    let _p = profile::span("render_macro");
+    MacroRender::new(ctx, name, macro_).render(import_to_add)
 }
 
 #[derive(Debug)]
@@ -38,10 +38,7 @@ impl<'a> MacroRender<'a> {
         MacroRender { ctx, name, macro_, docs, bra, ket }
     }
 
-    fn render(
-        &self,
-        import_data: Option<(ModPath, ImportScope, Option<MergeBehaviour>)>,
-    ) -> Option<CompletionItem> {
+    fn render(&self, import_to_add: Option<ImportToAdd>) -> Option<CompletionItem> {
         // FIXME: Currently proc-macro do not have ast-node,
         // such that it does not have source
         if self.macro_.is_proc_macro() {
@@ -53,7 +50,7 @@ impl<'a> MacroRender<'a> {
                 .kind(CompletionItemKind::Macro)
                 .set_documentation(self.docs.clone())
                 .set_deprecated(self.ctx.is_deprecated(self.macro_))
-                .import_data(import_data)
+                .add_import(import_to_add)
                 .detail(self.detail());
 
         let needs_bang = self.needs_bang();
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 37ed092ad..4500050f1 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -744,14 +744,13 @@ impl Function {
         Some(SelfParam { func: self.id })
     }
 
-    pub fn params(self, db: &dyn HirDatabase) -> Vec<Param> {
+    pub fn assoc_fn_params(self, db: &dyn HirDatabase) -> Vec<Param> {
         let resolver = self.id.resolver(db.upcast());
         let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
         let environment = TraitEnvironment::lower(db, &resolver);
         db.function_data(self.id)
             .params
             .iter()
-            .skip(if self.self_param(db).is_some() { 1 } else { 0 })
             .map(|type_ref| {
                 let ty = Type {
                     krate: self.id.lookup(db.upcast()).container.module(db.upcast()).krate,
@@ -764,6 +763,14 @@ impl Function {
             })
             .collect()
     }
+    pub fn method_params(self, db: &dyn HirDatabase) -> Option<Vec<Param>> {
+        if self.self_param(db).is_none() {
+            return None;
+        }
+        let mut res = self.assoc_fn_params(db);
+        res.remove(0);
+        Some(res)
+    }
 
     pub fn is_unsafe(self, db: &dyn HirDatabase) -> bool {
         db.function_data(self.id).is_unsafe
@@ -799,6 +806,7 @@ impl From<Mutability> for Access {
     }
 }
 
+#[derive(Debug)]
 pub struct Param {
     ty: Type,
 }
@@ -1420,11 +1428,11 @@ impl Type {
     pub fn normalize_trait_assoc_type(
         &self,
         db: &dyn HirDatabase,
-        r#trait: Trait,
+        trait_: Trait,
         args: &[Type],
         alias: TypeAlias,
     ) -> Option<Type> {
-        let subst = Substs::build_for_def(db, r#trait.id)
+        let subst = Substs::build_for_def(db, trait_.id)
             .push(self.ty.value.clone())
             .fill(args.iter().map(|t| t.ty.value.clone()))
             .build();
diff --git a/crates/hir/src/diagnostics.rs b/crates/hir/src/diagnostics.rs
index d9ad8db6f..eaf1a14ec 100644
--- a/crates/hir/src/diagnostics.rs
+++ b/crates/hir/src/diagnostics.rs
@@ -1,5 +1,5 @@
 //! FIXME: write short doc here
-pub use hir_def::diagnostics::{InactiveCode, UnresolvedModule};
+pub use hir_def::diagnostics::{InactiveCode, UnresolvedModule, UnresolvedProcMacro};
 pub use hir_expand::diagnostics::{
     Diagnostic, DiagnosticCode, DiagnosticSink, DiagnosticSinkBuilder,
 };
diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index d10b1af01..33eb5e78c 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -14,8 +14,8 @@ use cfg::CfgOptions;
 use drop_bomb::DropBomb;
 use either::Either;
 use hir_expand::{
-    ast_id_map::AstIdMap, diagnostics::DiagnosticSink, hygiene::Hygiene, AstId, HirFileId, InFile,
-    MacroDefId,
+    ast_id_map::AstIdMap, diagnostics::DiagnosticSink, hygiene::Hygiene, AstId, ExpandResult,
+    HirFileId, InFile, MacroDefId,
 };
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
@@ -102,11 +102,11 @@ impl Expander {
         db: &dyn DefDatabase,
         local_scope: Option<&ItemScope>,
         macro_call: ast::MacroCall,
-    ) -> Option<(Mark, T)> {
+    ) -> ExpandResult<Option<(Mark, T)>> {
         self.recursion_limit += 1;
         if self.recursion_limit > EXPANSION_RECURSION_LIMIT {
             mark::hit!(your_stack_belongs_to_me);
-            return None;
+            return ExpandResult::str_err("reached recursion limit during macro expansion".into());
         }
 
         let macro_call = InFile::new(self.current_file_id, &macro_call);
@@ -120,28 +120,55 @@ impl Expander {
             self.resolve_path_as_macro(db, &path)
         };
 
-        if let Some(call_id) = macro_call.as_call_id(db, self.crate_def_map.krate, resolver) {
-            let file_id = call_id.as_file();
-            if let Some(node) = db.parse_or_expand(file_id) {
-                if let Some(expr) = T::cast(node) {
-                    log::debug!("macro expansion {:#?}", expr.syntax());
-
-                    let mark = Mark {
-                        file_id: self.current_file_id,
-                        ast_id_map: mem::take(&mut self.ast_id_map),
-                        bomb: DropBomb::new("expansion mark dropped"),
-                    };
-                    self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
-                    self.current_file_id = file_id;
-                    self.ast_id_map = db.ast_id_map(file_id);
-                    return Some((mark, expr));
+        let call_id = match macro_call.as_call_id(db, self.crate_def_map.krate, resolver) {
+            Some(it) => it,
+            None => {
+                // FIXME: this can mean other things too, but `as_call_id` doesn't provide enough
+                // info.
+                return ExpandResult::only_err(mbe::ExpandError::Other(
+                    "failed to parse or resolve macro invocation".into(),
+                ));
+            }
+        };
+
+        let err = db.macro_expand_error(call_id);
+
+        let file_id = call_id.as_file();
+
+        let raw_node = match db.parse_or_expand(file_id) {
+            Some(it) => it,
+            None => {
+                // Only `None` if the macro expansion produced no usable AST.
+                if err.is_none() {
+                    log::warn!("no error despite `parse_or_expand` failing");
                 }
+
+                return ExpandResult::only_err(err.unwrap_or_else(|| {
+                    mbe::ExpandError::Other("failed to parse macro invocation".into())
+                }));
             }
-        }
+        };
+
+        let node = match T::cast(raw_node) {
+            Some(it) => it,
+            None => {
+                // This can happen without being an error, so only forward previous errors.
+                return ExpandResult { value: None, err };
+            }
+        };
+
+        log::debug!("macro expansion {:#?}", node.syntax());
+
+        let mark = Mark {
+            file_id: self.current_file_id,
+            ast_id_map: mem::take(&mut self.ast_id_map),
+            bomb: DropBomb::new("expansion mark dropped"),
+        };
+        self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
+        self.current_file_id = file_id;
+        self.ast_id_map = db.ast_id_map(file_id);
 
-        // FIXME: Instead of just dropping the error from expansion
-        // report it
-        None
+        ExpandResult { value: Some((mark, node)), err }
     }
 
     pub(crate) fn exit(&mut self, db: &dyn DefDatabase, mut mark: Mark) {
diff --git a/crates/hir_def/src/body/diagnostics.rs b/crates/hir_def/src/body/diagnostics.rs
index e57bdc133..1de7d30e2 100644
--- a/crates/hir_def/src/body/diagnostics.rs
+++ b/crates/hir_def/src/body/diagnostics.rs
@@ -2,11 +2,13 @@
 
 use hir_expand::diagnostics::DiagnosticSink;
 
-use crate::diagnostics::InactiveCode;
+use crate::diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro};
 
 #[derive(Debug, Eq, PartialEq)]
 pub(crate) enum BodyDiagnostic {
     InactiveCode(InactiveCode),
+    MacroError(MacroError),
+    UnresolvedProcMacro(UnresolvedProcMacro),
 }
 
 impl BodyDiagnostic {
@@ -15,6 +17,12 @@ impl BodyDiagnostic {
             BodyDiagnostic::InactiveCode(diag) => {
                 sink.push(diag.clone());
             }
+            BodyDiagnostic::MacroError(diag) => {
+                sink.push(diag.clone());
+            }
+            BodyDiagnostic::UnresolvedProcMacro(diag) => {
+                sink.push(diag.clone());
+            }
         }
     }
 }
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index cd7958746..2c41c0005 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -8,7 +8,7 @@ use either::Either;
 use hir_expand::{
     hygiene::Hygiene,
     name::{name, AsName, Name},
-    HirFileId, MacroDefId, MacroDefKind,
+    ExpandError, HirFileId, MacroDefId, MacroDefKind,
 };
 use rustc_hash::FxHashMap;
 use syntax::{
@@ -25,7 +25,7 @@ use crate::{
     body::{Body, BodySourceMap, Expander, PatPtr, SyntheticSyntax},
     builtin_type::{BuiltinFloat, BuiltinInt},
     db::DefDatabase,
-    diagnostics::InactiveCode,
+    diagnostics::{InactiveCode, MacroError, UnresolvedProcMacro},
     expr::{
         dummy_expr_id, ArithOp, Array, BinaryOp, BindingAnnotation, CmpOp, Expr, ExprId, Literal,
         LogicOp, MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement,
@@ -561,7 +561,32 @@ impl ExprCollector<'_> {
                     self.alloc_expr(Expr::Missing, syntax_ptr)
                 } else {
                     let macro_call = self.expander.to_source(AstPtr::new(&e));
-                    match self.expander.enter_expand(self.db, Some(&self.body.item_scope), e) {
+                    let res = self.expander.enter_expand(self.db, Some(&self.body.item_scope), e);
+
+                    match res.err {
+                        Some(ExpandError::UnresolvedProcMacro) => {
+                            self.source_map.diagnostics.push(BodyDiagnostic::UnresolvedProcMacro(
+                                UnresolvedProcMacro {
+                                    file: self.expander.current_file_id,
+                                    node: syntax_ptr.clone().into(),
+                                    precise_location: None,
+                                    macro_name: None,
+                                },
+                            ));
+                        }
+                        Some(err) => {
+                            self.source_map.diagnostics.push(BodyDiagnostic::MacroError(
+                                MacroError {
+                                    file: self.expander.current_file_id,
+                                    node: syntax_ptr.clone().into(),
+                                    message: err.to_string(),
+                                },
+                            ));
+                        }
+                        None => {}
+                    }
+
+                    match res.value {
                         Some((mark, expansion)) => {
                             self.source_map
                                 .expansions
diff --git a/crates/hir_def/src/data.rs b/crates/hir_def/src/data.rs
index ff1ef0df6..146045938 100644
--- a/crates/hir_def/src/data.rs
+++ b/crates/hir_def/src/data.rs
@@ -257,7 +257,7 @@ fn collect_items(
                 let root = db.parse_or_expand(file_id).unwrap();
                 let call = ast_id_map.get(call.ast_id).to_node(&root);
 
-                if let Some((mark, mac)) = expander.enter_expand(db, None, call) {
+                if let Some((mark, mac)) = expander.enter_expand(db, None, call).value {
                     let src: InFile<ast::MacroItems> = expander.to_source(mac);
                     let item_tree = db.item_tree(src.file_id);
                     let iter =
diff --git a/crates/hir_def/src/diagnostics.rs b/crates/hir_def/src/diagnostics.rs
index b221b290c..c71266dc0 100644
--- a/crates/hir_def/src/diagnostics.rs
+++ b/crates/hir_def/src/diagnostics.rs
@@ -6,7 +6,7 @@ use stdx::format_to;
 use cfg::{CfgExpr, CfgOptions, DnfExpr};
 use hir_expand::diagnostics::{Diagnostic, DiagnosticCode, DiagnosticSink};
 use hir_expand::{HirFileId, InFile};
-use syntax::{ast, AstPtr, SyntaxNodePtr};
+use syntax::{ast, AstPtr, SyntaxNodePtr, TextRange};
 
 use crate::{db::DefDatabase, DefWithBodyId};
 
@@ -127,3 +127,68 @@ impl Diagnostic for InactiveCode {
         self
     }
 }
+
+// Diagnostic: unresolved-proc-macro
+//
+// This diagnostic is shown when a procedural macro can not be found. This usually means that
+// procedural macro support is simply disabled (and hence is only a weak hint instead of an error),
+// but can also indicate project setup problems.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct UnresolvedProcMacro {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    /// If the diagnostic can be pinpointed more accurately than via `node`, this is the `TextRange`
+    /// to use instead.
+    pub precise_location: Option<TextRange>,
+    pub macro_name: Option<String>,
+}
+
+impl Diagnostic for UnresolvedProcMacro {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unresolved-proc-macro")
+    }
+
+    fn message(&self) -> String {
+        match &self.macro_name {
+            Some(name) => format!("proc macro `{}` not expanded", name),
+            None => "proc macro not expanded".to_string(),
+        }
+    }
+
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
+
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct MacroError {
+    pub file: HirFileId,
+    pub node: SyntaxNodePtr,
+    pub message: String,
+}
+
+impl Diagnostic for MacroError {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("macro-error")
+    }
+    fn message(&self) -> String {
+        self.message.clone()
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file, self.node.clone())
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+    fn is_experimental(&self) -> bool {
+        // Newly added and not very well-tested, might contain false positives.
+        true
+    }
+}
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index 202a7dcb6..ffd0381d4 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -286,8 +286,9 @@ mod diagnostics {
     use cfg::{CfgExpr, CfgOptions};
     use hir_expand::diagnostics::DiagnosticSink;
     use hir_expand::hygiene::Hygiene;
-    use hir_expand::InFile;
-    use syntax::{ast, AstPtr};
+    use hir_expand::{InFile, MacroCallKind};
+    use syntax::ast::AttrsOwner;
+    use syntax::{ast, AstNode, AstPtr, SyntaxKind, SyntaxNodePtr};
 
     use crate::path::ModPath;
     use crate::{db::DefDatabase, diagnostics::*, nameres::LocalModuleId, AstId};
@@ -301,6 +302,10 @@ mod diagnostics {
         UnresolvedImport { ast: AstId<ast::Use>, index: usize },
 
         UnconfiguredCode { ast: AstId<ast::Item>, cfg: CfgExpr, opts: CfgOptions },
+
+        UnresolvedProcMacro { ast: MacroCallKind },
+
+        MacroError { ast: MacroCallKind, message: String },
     }
 
     #[derive(Debug, PartialEq, Eq)]
@@ -348,6 +353,18 @@ mod diagnostics {
             Self { in_module: container, kind: DiagnosticKind::UnconfiguredCode { ast, cfg, opts } }
         }
 
+        pub(super) fn unresolved_proc_macro(container: LocalModuleId, ast: MacroCallKind) -> Self {
+            Self { in_module: container, kind: DiagnosticKind::UnresolvedProcMacro { ast } }
+        }
+
+        pub(super) fn macro_error(
+            container: LocalModuleId,
+            ast: MacroCallKind,
+            message: String,
+        ) -> Self {
+            Self { in_module: container, kind: DiagnosticKind::MacroError { ast, message } }
+        }
+
         pub(super) fn add_to(
             &self,
             db: &dyn DefDatabase,
@@ -407,6 +424,72 @@ mod diagnostics {
                         opts: opts.clone(),
                     });
                 }
+
+                DiagnosticKind::UnresolvedProcMacro { ast } => {
+                    let mut precise_location = None;
+                    let (file, ast, name) = match ast {
+                        MacroCallKind::FnLike(ast) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)), None)
+                        }
+                        MacroCallKind::Attr(ast, name) => {
+                            let node = ast.to_node(db.upcast());
+
+                            // Compute the precise location of the macro name's token in the derive
+                            // list.
+                            // FIXME: This does not handle paths to the macro, but neither does the
+                            // rest of r-a.
+                            let derive_attrs =
+                                node.attrs().filter_map(|attr| match attr.as_simple_call() {
+                                    Some((name, args)) if name == "derive" => Some(args),
+                                    _ => None,
+                                });
+                            'outer: for attr in derive_attrs {
+                                let tokens =
+                                    attr.syntax().children_with_tokens().filter_map(|elem| {
+                                        match elem {
+                                            syntax::NodeOrToken::Node(_) => None,
+                                            syntax::NodeOrToken::Token(tok) => Some(tok),
+                                        }
+                                    });
+                                for token in tokens {
+                                    if token.kind() == SyntaxKind::IDENT
+                                        && token.to_string() == *name
+                                    {
+                                        precise_location = Some(token.text_range());
+                                        break 'outer;
+                                    }
+                                }
+                            }
+
+                            (
+                                ast.file_id,
+                                SyntaxNodePtr::from(AstPtr::new(&node)),
+                                Some(name.clone()),
+                            )
+                        }
+                    };
+                    sink.push(UnresolvedProcMacro {
+                        file,
+                        node: ast,
+                        precise_location,
+                        macro_name: name,
+                    });
+                }
+
+                DiagnosticKind::MacroError { ast, message } => {
+                    let (file, ast) = match ast {
+                        MacroCallKind::FnLike(ast) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
+                        }
+                        MacroCallKind::Attr(ast, _) => {
+                            let node = ast.to_node(db.upcast());
+                            (ast.file_id, SyntaxNodePtr::from(AstPtr::new(&node)))
+                        }
+                    };
+                    sink.push(MacroError { file, node: ast, message: message.clone() });
+                }
             }
         }
     }
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 5ed9073e0..19cd713ba 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -7,7 +7,6 @@ use std::iter;
 
 use base_db::{CrateId, FileId, ProcMacroId};
 use cfg::{CfgExpr, CfgOptions};
-use hir_expand::InFile;
 use hir_expand::{
     ast_id_map::FileAstId,
     builtin_derive::find_builtin_derive,
@@ -16,6 +15,7 @@ use hir_expand::{
     proc_macro::ProcMacroExpander,
     HirFileId, MacroCallId, MacroDefId, MacroDefKind,
 };
+use hir_expand::{InFile, MacroCallLoc};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::ast;
 use test_utils::mark;
@@ -812,7 +812,30 @@ impl DefCollector<'_> {
             log::warn!("macro expansion is too deep");
             return;
         }
-        let file_id: HirFileId = macro_call_id.as_file();
+        let file_id = macro_call_id.as_file();
+
+        // First, fetch the raw expansion result for purposes of error reporting. This goes through
+        // `macro_expand_error` to avoid depending on the full expansion result (to improve
+        // incrementality).
+        let err = self.db.macro_expand_error(macro_call_id);
+        if let Some(err) = err {
+            if let MacroCallId::LazyMacro(id) = macro_call_id {
+                let loc: MacroCallLoc = self.db.lookup_intern_macro(id);
+
+                let diag = match err {
+                    hir_expand::ExpandError::UnresolvedProcMacro => {
+                        // Missing proc macros are non-fatal, so they are handled specially.
+                        DefDiagnostic::unresolved_proc_macro(module_id, loc.kind)
+                    }
+                    _ => DefDiagnostic::macro_error(module_id, loc.kind, err.to_string()),
+                };
+
+                self.def_map.diagnostics.push(diag);
+            }
+            // FIXME: Handle eager macros.
+        }
+
+        // Then, fetch and process the item tree. This will reuse the expansion result from above.
         let item_tree = self.db.item_tree(file_id);
         let mod_dir = self.mod_dirs[&module_id].clone();
         ModCollector {
diff --git a/crates/hir_def/src/nameres/tests/mod_resolution.rs b/crates/hir_def/src/nameres/tests/mod_resolution.rs
index ba295fd9e..ef6f85e15 100644
--- a/crates/hir_def/src/nameres/tests/mod_resolution.rs
+++ b/crates/hir_def/src/nameres/tests/mod_resolution.rs
@@ -798,3 +798,24 @@ mod foo;
 "#,
     );
 }
+
+#[test]
+fn abs_path_ignores_local() {
+    check(
+        r#"
+//- /main.rs crate:main deps:core
+pub use ::core::hash::Hash;
+pub mod core {}
+
+//- /lib.rs crate:core
+pub mod hash { pub trait Hash {} }
+"#,
+        expect![[r#"
+            crate
+            Hash: t
+            core: t
+
+            crate::core
+        "#]],
+    );
+}
diff --git a/crates/hir_def/src/path/lower/lower_use.rs b/crates/hir_def/src/path/lower/lower_use.rs
index 53cecb05f..ba0d1f0e7 100644
--- a/crates/hir_def/src/path/lower/lower_use.rs
+++ b/crates/hir_def/src/path/lower/lower_use.rs
@@ -76,7 +76,7 @@ fn convert_path(prefix: Option<ModPath>, path: ast::Path, hygiene: &Hygiene) ->
                 Either::Left(name) => {
                     // no type args in use
                     let mut res = prefix.unwrap_or_else(|| ModPath {
-                        kind: PathKind::Plain,
+                        kind: segment.coloncolon_token().map_or(PathKind::Plain, |_| PathKind::Abs),
                         segments: Vec::with_capacity(1),
                     });
                     res.segments.push(name);
diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
index aebbfc4df..7f4db106d 100644
--- a/crates/hir_expand/src/builtin_macro.rs
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -6,7 +6,7 @@ use crate::{
 
 use base_db::FileId;
 use either::Either;
-use mbe::parse_to_token_tree;
+use mbe::{parse_to_token_tree, ExpandResult};
 use parser::FragmentKind;
 use syntax::ast::{self, AstToken};
 
@@ -28,7 +28,7 @@ macro_rules! register_builtin {
                 db: &dyn AstDatabase,
                 id: LazyMacroId,
                 tt: &tt::Subtree,
-            ) -> Result<tt::Subtree, mbe::ExpandError> {
+            ) -> ExpandResult<tt::Subtree> {
                 let expander = match *self {
                     $( BuiltinFnLikeExpander::$kind => $expand, )*
                 };
@@ -42,7 +42,7 @@ macro_rules! register_builtin {
                 db: &dyn AstDatabase,
                 arg_id: EagerMacroId,
                 tt: &tt::Subtree,
-            ) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+            ) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
                 let expander = match *self {
                     $( EagerExpander::$e_kind => $e_expand, )*
                 };
@@ -109,25 +109,28 @@ fn line_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // dummy implementation for type-checking purposes
     let line_num = 0;
     let expanded = quote! {
         #line_num
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn stringify_expand(
     db: &dyn AstDatabase,
     id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     let loc = db.lookup_intern_macro(id);
 
     let macro_content = {
-        let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+        let arg = match loc.kind.arg(db) {
+            Some(arg) => arg,
+            None => return ExpandResult::only_err(mbe::ExpandError::UnexpectedToken),
+        };
         let macro_args = arg;
         let text = macro_args.text();
         let without_parens = TextSize::of('(')..text.len() - TextSize::of(')');
@@ -138,28 +141,28 @@ fn stringify_expand(
         #macro_content
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn column_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // dummy implementation for type-checking purposes
     let col_num = 0;
     let expanded = quote! {
         #col_num
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn assert_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // A hacky implementation for goto def and hover
     // We expand `assert!(cond, arg1, arg2)` to
     // ```
@@ -191,14 +194,14 @@ fn assert_expand(
     let expanded = quote! {
         { { (##arg_tts); } }
     };
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn file_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     _tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // FIXME: RA purposefully lacks knowledge of absolute file names
     // so just return "".
     let file_name = "";
@@ -207,31 +210,33 @@ fn file_expand(
         #file_name
     };
 
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn compile_error_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     if tt.count() == 1 {
         if let tt::TokenTree::Leaf(tt::Leaf::Literal(it)) = &tt.token_trees[0] {
             let s = it.text.as_str();
             if s.contains('"') {
-                return Ok(quote! { loop { #it }});
+                return ExpandResult::ok(quote! { loop { #it }});
             }
         };
     }
 
-    Err(mbe::ExpandError::BindingError("Must be a string".into()))
+    ExpandResult::only_err(mbe::ExpandError::BindingError(
+        "`compile_error!` argument be a string".into(),
+    ))
 }
 
 fn format_args_expand(
     _db: &dyn AstDatabase,
     _id: LazyMacroId,
     tt: &tt::Subtree,
-) -> Result<tt::Subtree, mbe::ExpandError> {
+) -> ExpandResult<tt::Subtree> {
     // We expand `format_args!("", a1, a2)` to
     // ```
     // std::fmt::Arguments::new_v1(&[], &[
@@ -257,7 +262,7 @@ fn format_args_expand(
         args.push(current);
     }
     if args.is_empty() {
-        return Err(mbe::ExpandError::NoMatchingRule);
+        return ExpandResult::only_err(mbe::ExpandError::NoMatchingRule);
     }
     let _format_string = args.remove(0);
     let arg_tts = args.into_iter().flat_map(|arg| {
@@ -266,7 +271,7 @@ fn format_args_expand(
     let expanded = quote! {
         std::fmt::Arguments::new_v1(&[], &[##arg_tts])
     };
-    Ok(expanded)
+    ExpandResult::ok(expanded)
 }
 
 fn unquote_str(lit: &tt::Literal) -> Option<String> {
@@ -279,19 +284,24 @@ fn concat_expand(
     _db: &dyn AstDatabase,
     _arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
     let mut text = String::new();
     for (i, t) in tt.token_trees.iter().enumerate() {
         match t {
             tt::TokenTree::Leaf(tt::Leaf::Literal(it)) if i % 2 == 0 => {
-                text += &unquote_str(&it).ok_or_else(|| mbe::ExpandError::ConversionError)?;
+                text += &match unquote_str(&it) {
+                    Some(s) => s,
+                    None => {
+                        return ExpandResult::only_err(mbe::ExpandError::ConversionError);
+                    }
+                };
             }
             tt::TokenTree::Leaf(tt::Leaf::Punct(punct)) if i % 2 == 1 && punct.char == ',' => (),
-            _ => return Err(mbe::ExpandError::UnexpectedToken),
+            _ => return ExpandResult::only_err(mbe::ExpandError::UnexpectedToken),
         }
     }
 
-    Ok((quote!(#text), FragmentKind::Expr))
+    ExpandResult::ok(Some((quote!(#text), FragmentKind::Expr)))
 }
 
 fn relative_file(
@@ -324,26 +334,35 @@ fn include_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let path = parse_string(tt)?;
-    let file_id = relative_file(db, arg_id.into(), &path, false)
-        .ok_or_else(|| mbe::ExpandError::ConversionError)?;
-
-    // FIXME:
-    // Handle include as expression
-    let res = parse_to_token_tree(&db.file_text(file_id))
-        .ok_or_else(|| mbe::ExpandError::ConversionError)?
-        .0;
-
-    Ok((res, FragmentKind::Items))
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let res = (|| {
+        let path = parse_string(tt)?;
+        let file_id = relative_file(db, arg_id.into(), &path, false)
+            .ok_or_else(|| mbe::ExpandError::ConversionError)?;
+
+        Ok(parse_to_token_tree(&db.file_text(file_id))
+            .ok_or_else(|| mbe::ExpandError::ConversionError)?
+            .0)
+    })();
+
+    match res {
+        Ok(res) => {
+            // FIXME:
+            // Handle include as expression
+            ExpandResult::ok(Some((res, FragmentKind::Items)))
+        }
+        Err(e) => ExpandResult::only_err(e),
+    }
 }
 
 fn include_bytes_expand(
     _db: &dyn AstDatabase,
     _arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let _path = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    if let Err(e) = parse_string(tt) {
+        return ExpandResult::only_err(e);
+    }
 
     // FIXME: actually read the file here if the user asked for macro expansion
     let res = tt::Subtree {
@@ -353,15 +372,18 @@ fn include_bytes_expand(
             id: tt::TokenId::unspecified(),
         }))],
     };
-    Ok((res, FragmentKind::Expr))
+    ExpandResult::ok(Some((res, FragmentKind::Expr)))
 }
 
 fn include_str_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let path = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let path = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
 
     // FIXME: we're not able to read excluded files (which is most of them because
     // it's unusual to `include_str!` a Rust file), but we can return an empty string.
@@ -370,14 +392,14 @@ fn include_str_expand(
     let file_id = match relative_file(db, arg_id.into(), &path, true) {
         Some(file_id) => file_id,
         None => {
-            return Ok((quote!(""), FragmentKind::Expr));
+            return ExpandResult::ok(Some((quote!(""), FragmentKind::Expr)));
         }
     };
 
     let text = db.file_text(file_id);
     let text = &*text;
 
-    Ok((quote!(#text), FragmentKind::Expr))
+    ExpandResult::ok(Some((quote!(#text), FragmentKind::Expr)))
 }
 
 fn get_env_inner(db: &dyn AstDatabase, arg_id: EagerMacroId, key: &str) -> Option<String> {
@@ -389,8 +411,11 @@ fn env_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let key = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let key = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
 
     // FIXME:
     // If the environment variable is not defined int rustc, then a compilation error will be emitted.
@@ -402,21 +427,25 @@ fn env_expand(
     let s = get_env_inner(db, arg_id, &key).unwrap_or_else(|| "__RA_UNIMPLEMENTED__".to_string());
     let expanded = quote! { #s };
 
-    Ok((expanded, FragmentKind::Expr))
+    ExpandResult::ok(Some((expanded, FragmentKind::Expr)))
 }
 
 fn option_env_expand(
     db: &dyn AstDatabase,
     arg_id: EagerMacroId,
     tt: &tt::Subtree,
-) -> Result<(tt::Subtree, FragmentKind), mbe::ExpandError> {
-    let key = parse_string(tt)?;
+) -> ExpandResult<Option<(tt::Subtree, FragmentKind)>> {
+    let key = match parse_string(tt) {
+        Ok(it) => it,
+        Err(e) => return ExpandResult::only_err(e),
+    };
+
     let expanded = match get_env_inner(db, arg_id, &key) {
         None => quote! { std::option::Option::None::<&str> },
         Some(s) => quote! { std::option::Some(#s) },
     };
 
-    Ok((expanded, FragmentKind::Expr))
+    ExpandResult::ok(Some((expanded, FragmentKind::Expr)))
 }
 
 #[cfg(test)]
@@ -485,7 +514,7 @@ mod tests {
                     }
                 });
 
-                let (subtree, fragment) = expander.expand(&db, arg_id, &parsed_args).unwrap();
+                let (subtree, fragment) = expander.expand(&db, arg_id, &parsed_args).value.unwrap();
                 let eager = EagerCallLoc {
                     def,
                     fragment,
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 46ebdbc74..4fd0ba290 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -3,7 +3,7 @@
 use std::sync::Arc;
 
 use base_db::{salsa, SourceDatabase};
-use mbe::{ExpandResult, MacroRules};
+use mbe::{ExpandError, ExpandResult, MacroRules};
 use parser::FragmentKind;
 use syntax::{algo::diff, AstNode, GreenNode, Parse, SyntaxKind::*, SyntaxNode};
 
@@ -30,8 +30,8 @@ impl TokenExpander {
     ) -> mbe::ExpandResult<tt::Subtree> {
         match self {
             TokenExpander::MacroRules(it) => it.expand(tt),
+            TokenExpander::Builtin(it) => it.expand(db, id, tt),
             // FIXME switch these to ExpandResult as well
-            TokenExpander::Builtin(it) => it.expand(db, id, tt).into(),
             TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
             TokenExpander::ProcMacro(_) => {
                 // We store the result in salsa db to prevent non-determinisc behavior in
@@ -81,6 +81,9 @@ pub trait AstDatabase: SourceDatabase {
     ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>>;
     fn macro_expand(&self, macro_call: MacroCallId) -> ExpandResult<Option<Arc<tt::Subtree>>>;
 
+    /// Firewall query that returns the error from the `macro_expand` query.
+    fn macro_expand_error(&self, macro_call: MacroCallId) -> Option<ExpandError>;
+
     #[salsa::interned]
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
 
@@ -171,6 +174,10 @@ fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Ar
     macro_expand_with_arg(db, id, None)
 }
 
+fn macro_expand_error(db: &dyn AstDatabase, macro_call: MacroCallId) -> Option<ExpandError> {
+    db.macro_expand(macro_call).err
+}
+
 fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
@@ -189,6 +196,7 @@ fn macro_expand_with_arg(
     id: MacroCallId,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<Arc<tt::Subtree>>> {
+    let _p = profile::span("macro_expand");
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
@@ -276,14 +284,15 @@ fn parse_macro_with_arg(
     macro_file: MacroFile,
     arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> ExpandResult<Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)>> {
-    let _p = profile::span("parse_macro_query");
-
     let macro_call_id = macro_file.macro_call_id;
     let result = if let Some(arg) = arg {
         macro_expand_with_arg(db, macro_call_id, Some(arg))
     } else {
         db.macro_expand(macro_call_id)
     };
+
+    let _p = profile::span("parse_macro_expansion");
+
     if let Some(err) = &result.err {
         // Note:
         // The final goal we would like to make all parse_macro success,
diff --git a/crates/hir_expand/src/diagnostics.rs b/crates/hir_expand/src/diagnostics.rs
index 1043c6aeb..bf0b85ce9 100644
--- a/crates/hir_expand/src/diagnostics.rs
+++ b/crates/hir_expand/src/diagnostics.rs
@@ -5,7 +5,7 @@
 //!
 //! `DiagnosticSink` struct is used as an emitter for diagnostic. When creating
 //! a `DiagnosticSink`, you supply a callback which can react to a `dyn
-//! Diagnostic` or to any concrete diagnostic (downcasting is sued internally).
+//! Diagnostic` or to any concrete diagnostic (downcasting is used internally).
 //!
 //! Because diagnostics store file offsets, it's a bad idea to store them
 //! directly in salsa. For this reason, every hir subsytem defines it's own
@@ -32,7 +32,12 @@ impl DiagnosticCode {
 pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
     fn code(&self) -> DiagnosticCode;
     fn message(&self) -> String;
-    /// Used in highlighting and related purposes
+    /// Source element that triggered the diagnostics.
+    ///
+    /// Note that this should reflect "semantics", rather than specific span we
+    /// want to highlight. When rendering the diagnostics into an error message,
+    /// the IDE will fetch the `SyntaxNode` and will narrow the span
+    /// appropriately.
     fn display_source(&self) -> InFile<SyntaxNodePtr>;
     fn as_any(&self) -> &(dyn Any + Send + 'static);
     fn is_experimental(&self) -> bool {
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 2f37d7189..ab6b4477c 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -65,7 +65,7 @@ pub fn expand_eager_macro(
     let subtree = to_subtree(&result)?;
 
     if let MacroDefKind::BuiltInEager(eager) = def.kind {
-        let (subtree, fragment) = eager.expand(db, arg_id, &subtree).ok()?;
+        let (subtree, fragment) = eager.expand(db, arg_id, &subtree).value?;
         let eager = EagerCallLoc {
             def,
             fragment,
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index d5ba691b7..6dad2507b 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -255,7 +255,7 @@ pub enum MacroDefKind {
 pub struct MacroCallLoc {
     pub(crate) def: MacroDefId,
     pub(crate) krate: CrateId,
-    pub(crate) kind: MacroCallKind,
+    pub kind: MacroCallKind,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index 7505cb061..97edf0fb6 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -50,7 +50,7 @@ impl ProcMacroExpander {
 
                 proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
             }
-            None => Err(err!("Unresolved proc macro")),
+            None => Err(mbe::ExpandError::UnresolvedProcMacro),
         }
     }
 }
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 3df73ed4f..9d3d88289 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -142,6 +142,15 @@ pub(crate) fn diagnostics(
                     .with_code(Some(d.code())),
             );
         })
+        .on::<hir::diagnostics::UnresolvedProcMacro, _>(|d| {
+            // Use more accurate position if available.
+            let display_range =
+                d.precise_location.unwrap_or_else(|| sema.diagnostics_display_range(d).range);
+
+            // FIXME: it would be nice to tell the user whether proc macros are currently disabled
+            res.borrow_mut()
+                .push(Diagnostic::hint(display_range, d.message()).with_code(Some(d.code())));
+        })
         // 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()));
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index 15792f947..b9810457f 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -1,14 +1,10 @@
 use hir::Semantics;
 use ide_db::{
+    base_db::FileId,
     defs::{NameClass, NameRefClass},
     symbol_index, RootDatabase,
 };
-use syntax::{
-    ast::{self},
-    match_ast, AstNode,
-    SyntaxKind::*,
-    SyntaxToken, TokenAtOffset, T,
-};
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
 
 use crate::{
     display::{ToNav, TryToNav},
@@ -44,6 +40,19 @@ pub(crate) fn goto_definition(
                 let nav = def.try_to_nav(sema.db)?;
                 vec![nav]
             },
+            ast::SelfParam(self_param) => {
+                vec![self_to_nav_target(self_param, position.file_id)?]
+            },
+            ast::PathSegment(segment) => {
+                segment.self_token()?;
+                let path = segment.parent_path();
+                if path.qualifier().is_some() && !ast::PathExpr::can_cast(path.syntax().parent()?.kind()) {
+                    return None;
+                }
+                let func = segment.syntax().ancestors().find_map(ast::Fn::cast)?;
+                let self_param = func.param_list()?.self_param()?;
+                vec![self_to_nav_target(self_param, position.file_id)?]
+            },
             _ => return None,
         }
     };
@@ -62,6 +71,20 @@ fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
     }
 }
 
+fn self_to_nav_target(self_param: ast::SelfParam, file_id: FileId) -> Option<NavigationTarget> {
+    let self_token = self_param.self_token()?;
+    Some(NavigationTarget {
+        file_id,
+        full_range: self_param.syntax().text_range(),
+        focus_range: Some(self_token.text_range()),
+        name: self_token.text().clone(),
+        kind: self_token.kind(),
+        container_name: None,
+        description: None,
+        docs: None,
+    })
+}
+
 #[derive(Debug)]
 pub(crate) enum ReferenceResult {
     Exact(NavigationTarget),
@@ -984,4 +1007,33 @@ fn g() -> <() as Iterator<A = (), B<|> = u8>>::A {}
 "#,
         );
     }
+
+    #[test]
+    fn goto_self_param_ty_specified() {
+        check(
+            r#"
+struct Foo {}
+
+impl Foo {
+    fn bar(self: &Foo) {
+         //^^^^
+        let foo = sel<|>f;
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn goto_self_param_on_decl() {
+        check(
+            r#"
+struct Foo {}
+
+impl Foo {
+    fn bar(&self<|>) {
+          //^^^^
+    }
+}"#,
+        )
+    }
 }
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index 832192881..462f5c2b8 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -139,14 +139,17 @@ pub(crate) fn hover(
         }
     }
 
-    let node = token
-        .ancestors()
-        .find(|n| ast::Expr::cast(n.clone()).is_some() || ast::Pat::cast(n.clone()).is_some())?;
+    let node = token.ancestors().find(|n| {
+        ast::Expr::can_cast(n.kind())
+            || ast::Pat::can_cast(n.kind())
+            || ast::SelfParam::can_cast(n.kind())
+    })?;
 
     let ty = match_ast! {
         match node {
             ast::Expr(it) => sema.type_of_expr(&it)?,
             ast::Pat(it) => sema.type_of_pat(&it)?,
+            ast::SelfParam(self_param) => sema.type_of_self(&self_param)?,
             // 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,
@@ -292,7 +295,6 @@ fn definition_owner_name(db: &RootDatabase, def: &Definition) -> Option<String>
             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())
@@ -354,7 +356,14 @@ fn hover_for_definition(db: &RootDatabase, def: Definition) -> Option<Markup> {
             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(_) => {
+        Definition::SelfType(impl_def) => {
+            impl_def.target_ty(db).as_adt().and_then(|adt| match adt {
+                Adt::Struct(it) => from_def_source(db, it, mod_path),
+                Adt::Union(it) => from_def_source(db, it, mod_path),
+                Adt::Enum(it) => from_def_source(db, it, mod_path),
+            })
+        }
+        Definition::TypeParam(_) => {
             // FIXME: Hover for generic param
             None
         }
@@ -1022,52 +1031,75 @@ impl Thing {
 }
 "#,
             expect![[r#"
-                *Self { x: 0 }*
+                *Self*
+
                 ```rust
-                Thing
+                test
+                ```
+
+                ```rust
+                struct Thing
                 ```
             "#]],
-        )
-    } /* FIXME: revive these tests
-              let (analysis, position) = fixture::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) = fixture::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) = fixture::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"));
-      */
+        );
+        check(
+            r#"
+struct Thing { x: u32 }
+impl Thing {
+    fn new() -> Self<|> { Self { x: 0 } }
+}
+"#,
+            expect![[r#"
+                *Self*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                struct Thing
+                ```
+            "#]],
+        );
+        check(
+            r#"
+enum Thing { A }
+impl Thing {
+    pub fn new() -> Self<|> { Thing::A }
+}
+"#,
+            expect![[r#"
+                *Self*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                enum Thing
+                ```
+            "#]],
+        );
+        check(
+            r#"
+        enum Thing { A }
+        impl Thing {
+            pub fn thing(a: Self<|>) {}
+        }
+        "#,
+            expect![[r#"
+                *Self*
+
+                ```rust
+                test
+                ```
+
+                ```rust
+                enum Thing
+                ```
+            "#]],
+        );
+    }
 
     #[test]
     fn test_hover_shadowing_pat() {
@@ -3282,4 +3314,41 @@ fn main() {
             "#]],
         );
     }
+
+    #[test]
+    fn hover_self_param_shows_type() {
+        check(
+            r#"
+struct Foo {}
+impl Foo {
+    fn bar(&sel<|>f) {}
+}
+"#,
+            expect![[r#"
+                *&self*
+                ```rust
+                &Foo
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
+    fn hover_self_param_shows_type_for_arbitrary_self_type() {
+        check(
+            r#"
+struct Arc<T>(T);
+struct Foo {}
+impl Foo {
+    fn bar(sel<|>f: Arc<Foo>) {}
+}
+"#,
+            expect![[r#"
+                *self: Arc<Foo>*
+                ```rust
+                Arc<Foo>
+                ```
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 6cfb22e13..65df7979c 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -1,6 +1,6 @@
-use assists::utils::FamousDefs;
 use either::Either;
 use hir::{known, Callable, HirDisplay, Semantics};
+use ide_db::helpers::FamousDefs;
 use ide_db::RootDatabase;
 use stdx::to_lower_snake_case;
 use syntax::{
@@ -427,8 +427,8 @@ fn get_callable(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Option<hir:
 
 #[cfg(test)]
 mod tests {
-    use assists::utils::FamousDefs;
     use expect_test::{expect, Expect};
+    use ide_db::helpers::FamousDefs;
     use test_utils::extract_annotations;
 
     use crate::{fixture, inlay_hints::InlayHintsConfig};
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 6288f7ea7..5244bdd61 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -87,9 +87,7 @@ pub use ide_db::{
     search::{Reference, ReferenceAccess, ReferenceKind},
 };
 
-pub use assists::{
-    utils::MergeBehaviour, Assist, AssistConfig, AssistId, AssistKind, ResolvedAssist,
-};
+pub use assists::{Assist, AssistConfig, AssistId, AssistKind, ResolvedAssist};
 pub use hir::{Documentation, Semantics};
 pub use ide_db::base_db::{
     Canceled, Change, CrateGraph, CrateId, Edition, FileId, FilePosition, FileRange, SourceRoot,
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
index 5693dd400..7395b81bd 100644
--- a/crates/ide/src/references.rs
+++ b/crates/ide/src/references.rs
@@ -21,7 +21,7 @@ use ide_db::{
 use syntax::{
     algo::find_node_at_offset,
     ast::{self, NameOwner},
-    AstNode, SyntaxKind, SyntaxNode, TextRange, TokenAtOffset,
+    match_ast, AstNode, SyntaxKind, SyntaxNode, TextRange, TokenAtOffset,
 };
 
 use crate::{display::TryToNav, FilePosition, FileRange, NavigationTarget, RangeInfo};
@@ -89,6 +89,10 @@ pub(crate) fn find_all_refs(
     let _p = profile::span("find_all_refs");
     let syntax = sema.parse(position.file_id).syntax().clone();
 
+    if let Some(res) = try_find_self_references(&syntax, position) {
+        return Some(res);
+    }
+
     let (opt_name, search_kind) = if let Some(name) =
         get_struct_def_name_for_struct_literal_search(&sema, &syntax, position)
     {
@@ -194,6 +198,77 @@ fn get_struct_def_name_for_struct_literal_search(
     None
 }
 
+fn try_find_self_references(
+    syntax: &SyntaxNode,
+    position: FilePosition,
+) -> Option<RangeInfo<ReferenceSearchResult>> {
+    let self_token =
+        syntax.token_at_offset(position.offset).find(|t| t.kind() == SyntaxKind::SELF_KW)?;
+    let parent = self_token.parent();
+    match_ast! {
+        match parent {
+            ast::SelfParam(it) => (),
+            ast::PathSegment(segment) => {
+                segment.self_token()?;
+                let path = segment.parent_path();
+                if path.qualifier().is_some() && !ast::PathExpr::can_cast(path.syntax().parent()?.kind()) {
+                    return None;
+                }
+            },
+            _ => return None,
+        }
+    };
+    let function = parent.ancestors().find_map(ast::Fn::cast)?;
+    let self_param = function.param_list()?.self_param()?;
+    let param_self_token = self_param.self_token()?;
+
+    let declaration = Declaration {
+        nav: NavigationTarget {
+            file_id: position.file_id,
+            full_range: self_param.syntax().text_range(),
+            focus_range: Some(param_self_token.text_range()),
+            name: param_self_token.text().clone(),
+            kind: param_self_token.kind(),
+            container_name: None,
+            description: None,
+            docs: None,
+        },
+        kind: ReferenceKind::SelfKw,
+        access: Some(if self_param.mut_token().is_some() {
+            ReferenceAccess::Write
+        } else {
+            ReferenceAccess::Read
+        }),
+    };
+    let references = function
+        .body()
+        .map(|body| {
+            body.syntax()
+                .descendants()
+                .filter_map(ast::PathExpr::cast)
+                .filter_map(|expr| {
+                    let path = expr.path()?;
+                    if path.qualifier().is_none() {
+                        path.segment()?.self_token()
+                    } else {
+                        None
+                    }
+                })
+                .map(|token| Reference {
+                    file_range: FileRange { file_id: position.file_id, range: token.text_range() },
+                    kind: ReferenceKind::SelfKw,
+                    access: declaration.access, // FIXME: properly check access kind here instead of copying it from the declaration
+                })
+                .collect()
+        })
+        .unwrap_or_default();
+
+    Some(RangeInfo::new(
+        param_self_token.text_range(),
+        ReferenceSearchResult { declaration, references },
+    ))
+}
+
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
@@ -762,6 +837,32 @@ fn f() -> m::En {
         );
     }
 
+    #[test]
+    fn test_find_self_refs() {
+        check(
+            r#"
+struct Foo { bar: i32 }
+
+impl Foo {
+    fn foo(self) {
+        let x = self<|>.bar;
+        if true {
+            let _ = match () {
+                () => self,
+            };
+        }
+    }
+}
+"#,
+            expect![[r#"
+                self SELF_KW FileId(0) 47..51 47..51 SelfKw Read
+
+                FileId(0) 71..75 SelfKw Read
+                FileId(0) 152..156 SelfKw Read
+            "#]],
+        );
+    }
+
     fn check(ra_fixture: &str, expect: Expect) {
         check_with_scope(ra_fixture, None, expect)
     }
diff --git a/crates/ide/src/references/rename.rs b/crates/ide/src/references/rename.rs
index 91c64bd4a..64fe8bd65 100644
--- a/crates/ide/src/references/rename.rs
+++ b/crates/ide/src/references/rename.rs
@@ -221,24 +221,47 @@ fn rename_to_self(
     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 (fn_def, fn_ast) = find_node_at_offset::<ast::Fn>(syn, position.offset)
+        .and_then(|fn_ast| sema.to_def(&fn_ast).zip(Some(fn_ast)))
         .ok_or_else(|| RenameError("No surrounding method declaration found".to_string()))?;
-    let params =
-        fn_def.param_list().ok_or_else(|| RenameError("Method has no parameters".to_string()))?;
-    if params.self_param().is_some() {
+    let param_range = fn_ast
+        .param_list()
+        .and_then(|p| p.params().next())
+        .ok_or_else(|| RenameError("Method has no parameters".to_string()))?
+        .syntax()
+        .text_range();
+    if !param_range.contains(position.offset) {
+        return Err(RenameError("Only the first parameter can be self".to_string()));
+    }
+
+    let impl_block = find_node_at_offset::<ast::Impl>(syn, position.offset)
+        .and_then(|def| sema.to_def(&def))
+        .ok_or_else(|| RenameError("No impl block found for function".to_string()))?;
+    if fn_def.self_param(sema.db).is_some() {
         return Err(RenameError("Method already has a self parameter".to_string()));
     }
+
+    let params = fn_def.assoc_fn_params(sema.db);
     let first_param =
-        params.params().next().ok_or_else(|| RenameError("Method has no parameters".into()))?;
-    let mutable = match first_param.ty() {
-        Some(ast::Type::RefType(rt)) => rt.mut_token().is_some(),
-        _ => return Err(RenameError("Not renaming other types".to_string())),
+        params.first().ok_or_else(|| RenameError("Method has no parameters".into()))?;
+    let first_param_ty = first_param.ty();
+    let impl_ty = impl_block.target_ty(sema.db);
+    let (ty, self_param) = if impl_ty.remove_ref().is_some() {
+        // if the impl is a ref to the type we can just match the `&T` with self directly
+        (first_param_ty.clone(), "self")
+    } else {
+        first_param_ty.remove_ref().map_or((first_param_ty.clone(), "self"), |ty| {
+            (ty, if first_param_ty.is_mutable_reference() { "&mut self" } else { "&self" })
+        })
     };
 
+    if ty != impl_ty {
+        return Err(RenameError("Parameter type differs from impl block type".to_string()));
+    }
+
     let RangeInfo { range, info: refs } = find_all_refs(sema, position, None)
         .ok_or_else(|| RenameError("No reference found at position".to_string()))?;
 
-    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());
@@ -254,10 +277,7 @@ fn rename_to_self(
 
     edits.push(SourceFileEdit {
         file_id: position.file_id,
-        edit: TextEdit::replace(
-            param_range,
-            String::from(if mutable { "&mut self" } else { "&self" }),
-        ),
+        edit: TextEdit::replace(param_range, String::from(self_param)),
     });
 
     Ok(RangeInfo::new(range, SourceChange::from(edits)))
@@ -280,7 +300,11 @@ fn text_edit_from_self_param(
 
     let mut replacement_text = String::from(new_name);
     replacement_text.push_str(": ");
-    replacement_text.push_str(self_param.mut_token().map_or("&", |_| "&mut "));
+    match (self_param.amp_token(), self_param.mut_token()) {
+        (None, None) => (),
+        (Some(_), None) => replacement_text.push('&'),
+        (_, Some(_)) => replacement_text.push_str("&mut "),
+    };
     replacement_text.push_str(type_name.as_str());
 
     Some(TextEdit::replace(self_param.syntax().text_range(), replacement_text))
@@ -1082,6 +1106,95 @@ impl Foo {
 }
 "#,
         );
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(foo<|>: Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(self) -> i32 {
+        self.i
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_parameter_to_self_error_no_impl() {
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+
+fn f(foo<|>: &mut Foo) -> i32 {
+    foo.i
+}
+"#,
+            "error: No impl block found for function",
+        );
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+struct Bar;
+
+impl Bar {
+    fn f(foo<|>: &mut Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+            "error: Parameter type differs from impl block type",
+        );
+    }
+
+    #[test]
+    fn test_parameter_to_self_error_not_first() {
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+impl Foo {
+    fn f(x: (), foo<|>: &mut Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+            "error: Only the first parameter can be self",
+        );
+    }
+
+    #[test]
+    fn test_parameter_to_self_impl_ref() {
+        check(
+            "self",
+            r#"
+struct Foo { i: i32 }
+impl &Foo {
+    fn f(foo<|>: &Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+impl &Foo {
+    fn f(self) -> i32 {
+        self.i
+    }
+}
+"#,
+        );
     }
 
     #[test]
@@ -1110,6 +1223,31 @@ impl Foo {
     }
 
     #[test]
+    fn test_owned_self_to_parameter() {
+        check(
+            "foo",
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(<|>self) -> i32 {
+        self.i
+    }
+}
+"#,
+            r#"
+struct Foo { i: i32 }
+
+impl Foo {
+    fn f(foo: Foo) -> i32 {
+        foo.i
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
     fn test_self_in_path_to_parameter() {
         check(
             "foo",
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 1ed77b40b..5150a970c 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -76,6 +76,7 @@ pub(crate) fn highlight(
     let mut current_macro_call: Option<ast::MacroCall> = None;
     let mut format_string_highlighter = FormatStringHighlighter::default();
     let mut macro_rules_highlighter = MacroRulesHighlighter::default();
+    let mut inside_attribute = false;
 
     // 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.
@@ -132,9 +133,12 @@ pub(crate) fn highlight(
             _ => (),
         }
 
-        // Check for Rust code in documentation
         match &event {
+            // Check for Rust code in documentation
             WalkEvent::Leave(NodeOrToken::Node(node)) => {
+                if ast::Attr::can_cast(node.kind()) {
+                    inside_attribute = false
+                }
                 if let Some((doctest, range_mapping, new_comments)) =
                     injection::extract_doc_comments(node)
                 {
@@ -146,6 +150,9 @@ pub(crate) fn highlight(
                     );
                 }
             }
+            WalkEvent::Enter(NodeOrToken::Node(node)) if ast::Attr::can_cast(node.kind()) => {
+                inside_attribute = true
+            }
             _ => (),
         }
 
@@ -188,12 +195,16 @@ pub(crate) fn highlight(
             }
         }
 
-        if let Some((highlight, binding_hash)) = highlight_element(
+        if let Some((mut highlight, binding_hash)) = highlight_element(
             &sema,
             &mut bindings_shadow_count,
             syntactic_name_ref_highlighting,
             element_to_highlight.clone(),
         ) {
+            if inside_attribute {
+                highlight = highlight | HighlightModifier::Attribute;
+            }
+
             if macro_rules_highlighter.highlight(element_to_highlight.clone()).is_none() {
                 stack.add(HighlightedRange { range, highlight, binding_hash });
             }
@@ -474,7 +485,9 @@ fn highlight_element(
 
         // Highlight references like the definitions they resolve to
         NAME_REF if element.ancestors().any(|it| it.kind() == ATTR) => {
-            Highlight::from(HighlightTag::Function) | HighlightModifier::Attribute
+            // even though we track whether we are in an attribute or not we still need this special case
+            // as otherwise we would emit unresolved references for name refs inside attributes
+            Highlight::from(HighlightTag::Function)
         }
         NAME_REF => {
             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html b/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
index 6be88f856..d79fa6dca 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
@@ -50,7 +50,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <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="generic injected"> </span><span class="attribute attribute injected">#</span><span class="attribute attribute injected">!</span><span class="attribute attribute injected">[</span><span class="function attribute injected">allow</span><span class="punctuation attribute injected">(</span><span class="attribute attribute injected">unused_mut</span><span class="punctuation attribute injected">)</span><span class="attribute 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 static">new</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html b/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
index 4b6d6adc9..1d05b7713 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
@@ -54,7 +54,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
 <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="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">repr</span><span class="punctuation attribute">(</span><span class="attribute attribute">packed</span><span class="punctuation attribute">)</span><span class="attribute 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>
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index 6a10a9dcd..15fbf2ce3 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -40,18 +40,18 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
 <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="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">lang</span><span class="attribute attribute"> </span><span class="operator attribute">=</span><span class="attribute attribute"> </span><span class="string_literal attribute">"copy"</span><span class="attribute 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="keyword">pub</span> <span class="keyword">mod</span> <span class="module declaration">ops</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">"fn_once"</span><span class="attribute">]</span>
+    <span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">lang</span><span class="attribute attribute"> </span><span class="operator attribute">=</span><span class="attribute attribute"> </span><span class="string_literal attribute">"fn_once"</span><span class="attribute attribute">]</span>
     <span class="keyword">pub</span> <span class="keyword">trait</span> <span class="trait declaration">FnOnce</span><span class="punctuation">&lt;</span><span class="type_param declaration">Args</span><span class="punctuation">&gt;</span> <span class="punctuation">{</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">"fn_mut"</span><span class="attribute">]</span>
+    <span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">lang</span><span class="attribute attribute"> </span><span class="operator attribute">=</span><span class="attribute attribute"> </span><span class="string_literal attribute">"fn_mut"</span><span class="attribute attribute">]</span>
     <span class="keyword">pub</span> <span class="keyword">trait</span> <span class="trait declaration">FnMut</span><span class="punctuation">&lt;</span><span class="type_param declaration">Args</span><span class="punctuation">&gt;</span><span class="punctuation">:</span> <span class="trait">FnOnce</span><span class="punctuation">&lt;</span><span class="type_param">Args</span><span class="punctuation">&gt;</span> <span class="punctuation">{</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">"fn"</span><span class="attribute">]</span>
+    <span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">lang</span><span class="attribute attribute"> </span><span class="operator attribute">=</span><span class="attribute attribute"> </span><span class="string_literal attribute">"fn"</span><span class="attribute attribute">]</span>
     <span class="keyword">pub</span> <span class="keyword">trait</span> <span class="trait declaration">Fn</span><span class="punctuation">&lt;</span><span class="type_param declaration">Args</span><span class="punctuation">&gt;</span><span class="punctuation">:</span> <span class="trait">FnMut</span><span class="punctuation">&lt;</span><span class="type_param">Args</span><span class="punctuation">&gt;</span> <span class="punctuation">{</span><span class="punctuation">}</span>
 <span class="punctuation">}</span>
 
@@ -85,7 +85,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <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">]</span>
+<span class="attribute attribute">#</span><span class="attribute attribute">[</span><span class="function attribute">derive</span><span class="punctuation attribute">(</span><span class="attribute attribute">Copy</span><span class="punctuation attribute">)</span><span class="attribute 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>
diff --git a/crates/ide_db/Cargo.toml b/crates/ide_db/Cargo.toml
index 72a9212f1..0ad6e1000 100644
--- a/crates/ide_db/Cargo.toml
+++ b/crates/ide_db/Cargo.toml
@@ -18,7 +18,8 @@ rayon = "1.5.0"
 fst = { version = "0.4", default-features = false }
 rustc-hash = "1.1.0"
 once_cell = "1.3.1"
-either = "1.5.3"
+either = "1.6.1"
+itertools = "0.9.0"
 
 stdx = { path = "../stdx", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
diff --git a/crates/ide_db/src/helpers.rs b/crates/ide_db/src/helpers.rs
new file mode 100644
index 000000000..d988588ff
--- /dev/null
+++ b/crates/ide_db/src/helpers.rs
@@ -0,0 +1,203 @@
+//! A module with ide helpers for high-level ide features.
+use crate::RootDatabase;
+use hir::{Crate, Enum, Module, ScopeDef, Semantics, Trait};
+use syntax::ast::{self, make};
+
+pub mod insert_use;
+
+/// Converts the mod path struct into its ast representation.
+pub fn mod_path_to_ast(path: &hir::ModPath) -> ast::Path {
+    let _p = profile::span("mod_path_to_ast");
+
+    let mut segments = Vec::new();
+    let mut is_abs = false;
+    match path.kind {
+        hir::PathKind::Plain => {}
+        hir::PathKind::Super(0) => segments.push(make::path_segment_self()),
+        hir::PathKind::Super(n) => segments.extend((0..n).map(|_| make::path_segment_super())),
+        hir::PathKind::DollarCrate(_) | hir::PathKind::Crate => {
+            segments.push(make::path_segment_crate())
+        }
+        hir::PathKind::Abs => is_abs = true,
+    }
+
+    segments.extend(
+        path.segments
+            .iter()
+            .map(|segment| make::path_segment(make::name_ref(&segment.to_string()))),
+    );
+    make::path_from_segments(segments, is_abs)
+}
+
+/// Helps with finding well-know things inside the standard library. This is
+/// somewhat similar to the known paths infra inside hir, but it different; We
+/// want to make sure that IDE specific paths don't become interesting inside
+/// the compiler itself as well.
+pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Crate>);
+
+#[allow(non_snake_case)]
+impl FamousDefs<'_, '_> {
+    pub const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
+pub mod convert {
+    pub trait From<T> {
+        fn from(t: T) -> Self;
+    }
+}
+
+pub mod default {
+    pub trait Default {
+       fn default() -> Self;
+    }
+}
+
+pub mod iter {
+    pub use self::traits::{collect::IntoIterator, iterator::Iterator};
+    mod traits {
+        pub(crate) mod iterator {
+            use crate::option::Option;
+            pub trait Iterator {
+                type Item;
+                fn next(&mut self) -> Option<Self::Item>;
+                fn by_ref(&mut self) -> &mut Self {
+                    self
+                }
+                fn take(self, n: usize) -> crate::iter::Take<Self> {
+                    crate::iter::Take { inner: self }
+                }
+            }
+
+            impl<I: Iterator> Iterator for &mut I {
+                type Item = I::Item;
+                fn next(&mut self) -> Option<I::Item> {
+                    (**self).next()
+                }
+            }
+        }
+        pub(crate) mod collect {
+            pub trait IntoIterator {
+                type Item;
+            }
+        }
+    }
+
+    pub use self::sources::*;
+    pub(crate) mod sources {
+        use super::Iterator;
+        use crate::option::Option::{self, *};
+        pub struct Repeat<A> {
+            element: A,
+        }
+
+        pub fn repeat<T>(elt: T) -> Repeat<T> {
+            Repeat { element: elt }
+        }
+
+        impl<A> Iterator for Repeat<A> {
+            type Item = A;
+
+            fn next(&mut self) -> Option<A> {
+                None
+            }
+        }
+    }
+
+    pub use self::adapters::*;
+    pub(crate) mod adapters {
+        use super::Iterator;
+        use crate::option::Option::{self, *};
+        pub struct Take<I> { pub(crate) inner: I }
+        impl<I> Iterator for Take<I> where I: Iterator {
+            type Item = <I as Iterator>::Item;
+            fn next(&mut self) -> Option<<I as Iterator>::Item> {
+                None
+            }
+        }
+    }
+}
+
+pub mod option {
+    pub enum Option<T> { None, Some(T)}
+}
+
+pub mod prelude {
+    pub use crate::{convert::From, iter::{IntoIterator, Iterator}, option::Option::{self, *}, default::Default};
+}
+#[prelude_import]
+pub use prelude::*;
+"#;
+
+    pub fn core(&self) -> Option<Crate> {
+        self.find_crate("core")
+    }
+
+    pub fn core_convert_From(&self) -> Option<Trait> {
+        self.find_trait("core:convert:From")
+    }
+
+    pub fn core_option_Option(&self) -> Option<Enum> {
+        self.find_enum("core:option:Option")
+    }
+
+    pub fn core_default_Default(&self) -> Option<Trait> {
+        self.find_trait("core:default:Default")
+    }
+
+    pub fn core_iter_Iterator(&self) -> Option<Trait> {
+        self.find_trait("core:iter:traits:iterator:Iterator")
+    }
+
+    pub fn core_iter(&self) -> Option<Module> {
+        self.find_module("core:iter")
+    }
+
+    fn find_trait(&self, path: &str) -> Option<Trait> {
+        match self.find_def(path)? {
+            hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
+            _ => None,
+        }
+    }
+
+    fn find_enum(&self, path: &str) -> Option<Enum> {
+        match self.find_def(path)? {
+            hir::ScopeDef::ModuleDef(hir::ModuleDef::Adt(hir::Adt::Enum(it))) => Some(it),
+            _ => None,
+        }
+    }
+
+    fn find_module(&self, path: &str) -> Option<Module> {
+        match self.find_def(path)? {
+            hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(it)) => Some(it),
+            _ => None,
+        }
+    }
+
+    fn find_crate(&self, name: &str) -> Option<Crate> {
+        let krate = self.1?;
+        let db = self.0.db;
+        let res =
+            krate.dependencies(db).into_iter().find(|dep| dep.name.to_string() == name)?.krate;
+        Some(res)
+    }
+
+    fn find_def(&self, path: &str) -> Option<ScopeDef> {
+        let db = self.0.db;
+        let mut path = path.split(':');
+        let trait_ = path.next_back()?;
+        let std_crate = path.next()?;
+        let std_crate = self.find_crate(std_crate)?;
+        let mut module = std_crate.root_module(db);
+        for segment in path {
+            module = module.children(db).find_map(|child| {
+                let name = child.name(db)?;
+                if name.to_string() == segment {
+                    Some(child)
+                } else {
+                    None
+                }
+            })?;
+        }
+        let def =
+            module.scope(db, None).into_iter().find(|(name, _def)| name.to_string() == trait_)?.1;
+        Some(def)
+    }
+}
diff --git a/crates/assists/src/utils/insert_use.rs b/crates/ide_db/src/helpers/insert_use.rs
index 423782a0e..08d246c16 100644
--- a/crates/assists/src/utils/insert_use.rs
+++ b/crates/ide_db/src/helpers/insert_use.rs
@@ -1,8 +1,8 @@
 //! Handle syntactic aspects of inserting a new `use`.
 use std::{cmp::Ordering, iter::successors};
 
+use crate::RootDatabase;
 use hir::Semantics;
-use ide_db::RootDatabase;
 use itertools::{EitherOrBoth, Itertools};
 use syntax::{
     algo::SyntaxRewriter,
@@ -22,7 +22,7 @@ pub enum ImportScope {
 }
 
 impl ImportScope {
-    pub(crate) fn from(syntax: SyntaxNode) -> Option<Self> {
+    pub fn from(syntax: SyntaxNode) -> Option<Self> {
         if let Some(module) = ast::Module::cast(syntax.clone()) {
             module.item_list().map(ImportScope::Module)
         } else if let this @ Some(_) = ast::SourceFile::cast(syntax.clone()) {
@@ -95,6 +95,7 @@ pub fn insert_use<'a>(
     path: ast::Path,
     merge: Option<MergeBehaviour>,
 ) -> SyntaxRewriter<'a> {
+    let _p = profile::span("insert_use");
     let mut rewriter = SyntaxRewriter::default();
     let use_item = make::use_(make::use_tree(path.clone(), None, None, false));
     // merge into existing imports if possible
@@ -179,7 +180,7 @@ fn eq_visibility(vis0: Option<ast::Visibility>, vis1: Option<ast::Visibility>) -
     }
 }
 
-pub(crate) fn try_merge_imports(
+pub fn try_merge_imports(
     lhs: &ast::Use,
     rhs: &ast::Use,
     merge_behaviour: MergeBehaviour,
@@ -194,7 +195,7 @@ pub(crate) fn try_merge_imports(
     Some(lhs.with_use_tree(merged))
 }
 
-pub(crate) fn try_merge_trees(
+pub fn try_merge_trees(
     lhs: &ast::UseTree,
     rhs: &ast::UseTree,
     merge: MergeBehaviour,
@@ -383,7 +384,7 @@ fn path_cmp_for_sort(a: Option<ast::Path>, b: Option<ast::Path>) -> Ordering {
 
 /// Path comparison func for binary searching for merging.
 fn path_cmp_bin_search(lhs: Option<ast::Path>, rhs: Option<ast::Path>) -> Ordering {
-    match (lhs.and_then(|path| path.segment()), rhs.and_then(|path| path.segment())) {
+    match (lhs.as_ref().and_then(first_segment), rhs.as_ref().and_then(first_segment)) {
         (None, None) => Ordering::Equal,
         (None, Some(_)) => Ordering::Less,
         (Some(_), None) => Ordering::Greater,
@@ -1081,6 +1082,15 @@ use std::io;",
     }
 
     #[test]
+    fn merge_nested_considers_first_segments() {
+        check_full(
+            "hir_ty::display::write_bounds_like_dyn_trait",
+            r"use hir_ty::{autoderef, display::{HirDisplayError, HirFormatter}, method_resolution};",
+            r"use hir_ty::{autoderef, display::{HirDisplayError, HirFormatter, write_bounds_like_dyn_trait}, method_resolution};",
+        );
+    }
+
+    #[test]
     fn skip_merge_last_too_long() {
         check_last(
             "foo::bar",
diff --git a/crates/ide_db/src/lib.rs b/crates/ide_db/src/lib.rs
index 05139a651..fceaa089a 100644
--- a/crates/ide_db/src/lib.rs
+++ b/crates/ide_db/src/lib.rs
@@ -13,6 +13,7 @@ pub mod source_change;
 pub mod ty_filter;
 pub mod traits;
 pub mod call_info;
+pub mod helpers;
 
 use std::{fmt, sync::Arc};
 
diff --git a/crates/ide_db/src/search.rs b/crates/ide_db/src/search.rs
index a3e765d05..607185ca9 100644
--- a/crates/ide_db/src/search.rs
+++ b/crates/ide_db/src/search.rs
@@ -31,6 +31,7 @@ pub enum ReferenceKind {
     FieldShorthandForLocal,
     StructLiteral,
     RecordFieldExprOrPat,
+    SelfKw,
     Other,
 }
 
diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index 2d0763c47..3ad609a00 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -35,6 +35,7 @@ pub enum ExpandError {
     ConversionError,
     InvalidRepeat,
     ProcMacroError(tt::ExpansionError),
+    UnresolvedProcMacro,
     Other(String),
 }
 
@@ -53,6 +54,7 @@ impl fmt::Display for ExpandError {
             ExpandError::ConversionError => f.write_str("could not convert tokens"),
             ExpandError::InvalidRepeat => f.write_str("invalid repeat expression"),
             ExpandError::ProcMacroError(e) => e.fmt(f),
+            ExpandError::UnresolvedProcMacro => f.write_str("unresolved proc macro"),
             ExpandError::Other(e) => f.write_str(e),
         }
     }
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index 436f5041b..0a055b039 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -21,7 +21,7 @@ env_logger = { version = "0.8.1", default-features = false }
 itertools = "0.9.0"
 jod-thread = "0.1.0"
 log = "0.4.8"
-lsp-types = { version = "0.84.0", features = ["proposed"] }
+lsp-types = { version = "0.85.0", features = ["proposed"] }
 parking_lot = "0.11.0"
 pico-args = "0.3.1"
 oorandom = "11.1.2"
@@ -39,6 +39,7 @@ tracing-tree = { version = "0.1.4" }
 stdx = { path = "../stdx", version = "0.0.0" }
 flycheck = { path = "../flycheck", version = "0.0.0" }
 ide = { path = "../ide", version = "0.0.0" }
+ide_db = { path = "../ide_db", version = "0.0.0" }
 profile = { path = "../profile", version = "0.0.0" }
 project_model = { path = "../project_model", version = "0.0.0" }
 syntax = { path = "../syntax", version = "0.0.0" }
@@ -49,7 +50,6 @@ cfg = { path = "../cfg", version = "0.0.0" }
 toolchain = { path = "../toolchain", version = "0.0.0" }
 
 # This should only be used in CLI
-ide_db = { path = "../ide_db", version = "0.0.0" }
 ssr = { path = "../ssr", version = "0.0.0" }
 hir = { path = "../hir", version = "0.0.0" }
 hir_def = { path = "../hir_def", version = "0.0.0" }
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index a334cdb11..59269a74b 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -11,10 +11,8 @@ use std::{convert::TryFrom, ffi::OsString, path::PathBuf};
 
 use flycheck::FlycheckConfig;
 use hir::PrefixKind;
-use ide::{
-    AssistConfig, CompletionConfig, DiagnosticsConfig, HoverConfig, InlayHintsConfig,
-    MergeBehaviour,
-};
+use ide::{AssistConfig, CompletionConfig, DiagnosticsConfig, HoverConfig, InlayHintsConfig};
+use ide_db::helpers::insert_use::MergeBehaviour;
 use lsp_types::{ClientCapabilities, MarkupKind};
 use project_model::{CargoConfig, ProjectJson, ProjectJsonData, ProjectManifest};
 use rustc_hash::FxHashSet;
@@ -482,7 +480,7 @@ macro_rules! config_data {
 
 config_data! {
     struct ConfigData {
-        assist_importMergeBehaviour: MergeBehaviourDef = MergeBehaviourDef::None,
+        assist_importMergeBehaviour: MergeBehaviourDef = MergeBehaviourDef::Full,
         assist_importPrefix: ImportPrefixDef           = ImportPrefixDef::Plain,
 
         callInfo_full: bool = true,
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 866d1d176..f349b0810 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -289,55 +289,69 @@ impl GlobalState {
                     }
                 }
             }
-            Event::Flycheck(task) => match task {
-                flycheck::Message::AddDiagnostic { workspace_root, diagnostic } => {
-                    let diagnostics = crate::diagnostics::to_proto::map_rust_diagnostic_to_lsp(
-                        &self.config.diagnostics_map,
-                        &diagnostic,
-                        &workspace_root,
-                    );
-                    for diag in diagnostics {
-                        match url_to_file_id(&self.vfs.read().0, &diag.url) {
-                            Ok(file_id) => self.diagnostics.add_check_diagnostic(
-                                file_id,
-                                diag.diagnostic,
-                                diag.fixes,
-                            ),
-                            Err(err) => {
-                                log::error!("File with cargo diagnostic not found in VFS: {}", err);
-                            }
-                        };
-                    }
-                }
-
-                flycheck::Message::Progress { id, progress } => {
-                    let (state, message) = match progress {
-                        flycheck::Progress::DidStart => {
-                            self.diagnostics.clear_check();
-                            (Progress::Begin, None)
-                        }
-                        flycheck::Progress::DidCheckCrate(target) => {
-                            (Progress::Report, Some(target))
-                        }
-                        flycheck::Progress::DidCancel => (Progress::End, None),
-                        flycheck::Progress::DidFinish(result) => {
-                            if let Err(err) = result {
-                                log::error!("cargo check failed: {}", err)
+            Event::Flycheck(mut task) => {
+                let _p = profile::span("GlobalState::handle_event/flycheck");
+                loop {
+                    match task {
+                        flycheck::Message::AddDiagnostic { workspace_root, diagnostic } => {
+                            let diagnostics =
+                                crate::diagnostics::to_proto::map_rust_diagnostic_to_lsp(
+                                    &self.config.diagnostics_map,
+                                    &diagnostic,
+                                    &workspace_root,
+                                );
+                            for diag in diagnostics {
+                                match url_to_file_id(&self.vfs.read().0, &diag.url) {
+                                    Ok(file_id) => self.diagnostics.add_check_diagnostic(
+                                        file_id,
+                                        diag.diagnostic,
+                                        diag.fixes,
+                                    ),
+                                    Err(err) => {
+                                        log::error!(
+                                            "File with cargo diagnostic not found in VFS: {}",
+                                            err
+                                        );
+                                    }
+                                };
                             }
-                            (Progress::End, None)
                         }
-                    };
 
-                    // When we're running multiple flychecks, we have to include a disambiguator in
-                    // the title, or the editor complains. Note that this is a user-facing string.
-                    let title = if self.flycheck.len() == 1 {
-                        "cargo check".to_string()
-                    } else {
-                        format!("cargo check (#{})", id + 1)
-                    };
-                    self.report_progress(&title, state, message, None);
+                        flycheck::Message::Progress { id, progress } => {
+                            let (state, message) = match progress {
+                                flycheck::Progress::DidStart => {
+                                    self.diagnostics.clear_check();
+                                    (Progress::Begin, None)
+                                }
+                                flycheck::Progress::DidCheckCrate(target) => {
+                                    (Progress::Report, Some(target))
+                                }
+                                flycheck::Progress::DidCancel => (Progress::End, None),
+                                flycheck::Progress::DidFinish(result) => {
+                                    if let Err(err) = result {
+                                        log::error!("cargo check failed: {}", err)
+                                    }
+                                    (Progress::End, None)
+                                }
+                            };
+
+                            // When we're running multiple flychecks, we have to include a disambiguator in
+                            // the title, or the editor complains. Note that this is a user-facing string.
+                            let title = if self.flycheck.len() == 1 {
+                                "cargo check".to_string()
+                            } else {
+                                format!("cargo check (#{})", id + 1)
+                            };
+                            self.report_progress(&title, state, message, None);
+                        }
+                    }
+                    // Coalesce many flycheck updates into a single loop turn
+                    task = match self.flycheck_receiver.try_recv() {
+                        Ok(task) => task,
+                        Err(_) => break,
+                    }
                 }
-            },
+            }
         }
 
         let state_changed = self.process_changes();
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index 001bf5949..b2d35f535 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -205,7 +205,7 @@ impl GlobalState {
                 }
                 let res = vfs.file_id(&vfs_path);
                 if res.is_none() {
-                    log::error!("failed to load {}", path.display())
+                    log::warn!("failed to load {}", path.display())
                 }
                 res
             };
diff --git a/crates/rust-analyzer/src/semantic_tokens.rs b/crates/rust-analyzer/src/semantic_tokens.rs
index e7991fd28..1daad1c98 100644
--- a/crates/rust-analyzer/src/semantic_tokens.rs
+++ b/crates/rust-analyzer/src/semantic_tokens.rs
@@ -27,7 +27,7 @@ macro_rules! define_semantic_token_types {
             SemanticTokenType::ENUM_MEMBER,
             SemanticTokenType::TYPE_PARAMETER,
             SemanticTokenType::FUNCTION,
-            SemanticTokenType::MEMBER,
+            SemanticTokenType::METHOD,
             SemanticTokenType::PROPERTY,
             SemanticTokenType::MACRO,
             SemanticTokenType::VARIABLE,
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index 1fe907753..c6a6f11e1 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 itertools = "0.9.0"
 rowan = "0.10.0"
-rustc_lexer = { version = "688.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer = { version = "691.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 arrayvec = "0.5.1"
 once_cell = "1.3.1"
@@ -28,6 +28,7 @@ stdx = { path = "../stdx", version = "0.0.0" }
 text_edit = { path = "../text_edit", version = "0.0.0" }
 parser = { path = "../parser", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
+profile = { path = "../profile", version = "0.0.0" }
 
 [dev-dependencies]
 walkdir = "2.3.1"
diff --git a/crates/syntax/src/algo.rs b/crates/syntax/src/algo.rs
index 320c430c9..ee89d9867 100644
--- a/crates/syntax/src/algo.rs
+++ b/crates/syntax/src/algo.rs
@@ -127,6 +127,8 @@ pub struct TreeDiff {
 
 impl TreeDiff {
     pub fn into_text_edit(&self, builder: &mut TextEditBuilder) {
+        let _p = profile::span("into_text_edit");
+
         for (anchor, to) in self.insertions.iter() {
             let offset = match anchor {
                 TreeDiffInsertPos::After(it) => it.text_range().end(),
@@ -154,6 +156,8 @@ impl TreeDiff {
 ///
 /// This function tries to find a fine-grained diff.
 pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
+    let _p = profile::span("diff");
+
     let mut diff = TreeDiff {
         replacements: FxHashMap::default(),
         insertions: FxIndexMap::default(),
@@ -467,6 +471,8 @@ impl<'a> SyntaxRewriter<'a> {
     }
 
     pub fn rewrite(&self, node: &SyntaxNode) -> SyntaxNode {
+        let _p = profile::span("rewrite");
+
         if self.f.is_none() && self.replacements.is_empty() && self.insertions.is_empty() {
             return node.clone();
         }
@@ -483,6 +489,7 @@ impl<'a> SyntaxRewriter<'a> {
     ///
     /// Returns `None` when there are no replacements.
     pub fn rewrite_root(&self) -> Option<SyntaxNode> {
+        let _p = profile::span("rewrite_root");
         fn element_to_node_or_parent(element: &SyntaxElement) -> SyntaxNode {
             match element {
                 SyntaxElement::Node(it) => it.clone(),
@@ -517,6 +524,8 @@ impl<'a> SyntaxRewriter<'a> {
     }
 
     fn rewrite_children(&self, node: &SyntaxNode) -> SyntaxNode {
+        let _p = profile::span("rewrite_children");
+
         //  FIXME: this could be made much faster.
         let mut new_children = Vec::new();
         if let Some(elements) = self.insertions(&InsertPos::FirstChildOf(node.clone())) {
@@ -533,6 +542,8 @@ impl<'a> SyntaxRewriter<'a> {
         acc: &mut Vec<NodeOrToken<rowan::GreenNode, rowan::GreenToken>>,
         element: &SyntaxElement,
     ) {
+        let _p = profile::span("rewrite_self");
+
         if let Some(replacement) = self.replacement(&element) {
             match replacement {
                 Replacement::Single(element) => acc.push(element_to_green(element)),
@@ -588,6 +599,8 @@ fn with_children(
     parent: &SyntaxNode,
     new_children: Vec<NodeOrToken<rowan::GreenNode, rowan::GreenToken>>,
 ) -> SyntaxNode {
+    let _p = profile::span("with_children");
+
     let len = new_children.iter().map(|it| it.text_len()).sum::<TextSize>();
     let new_node = rowan::GreenNode::new(rowan::SyntaxKind(parent.kind() as u16), new_children);
     let new_root_node = parent.replace_with(new_node);
diff --git a/crates/syntax/src/ast/token_ext.rs b/crates/syntax/src/ast/token_ext.rs
index 0c178039e..fa40e64e8 100644
--- a/crates/syntax/src/ast/token_ext.rs
+++ b/crates/syntax/src/ast/token_ext.rs
@@ -130,19 +130,28 @@ impl ast::String {
         let text = self.text().as_str();
         let text = &text[self.text_range_between_quotes()? - self.syntax().text_range().start()];
 
-        let mut buf = String::with_capacity(text.len());
+        let mut buf = String::new();
+        let mut text_iter = text.chars();
         let mut has_error = false;
-        unescape_literal(text, Mode::Str, &mut |_, unescaped_char| match unescaped_char {
-            Ok(c) => buf.push(c),
-            Err(_) => has_error = true,
+        unescape_literal(text, Mode::Str, &mut |char_range, unescaped_char| match (
+            unescaped_char,
+            buf.capacity() == 0,
+        ) {
+            (Ok(c), false) => buf.push(c),
+            (Ok(c), true) if Some(c) == text_iter.next() => (),
+            (Ok(c), true) => {
+                buf.reserve_exact(text.len());
+                buf.push_str(&text[..char_range.start]);
+                buf.push(c);
+            }
+            (Err(_), _) => has_error = true,
         });
 
-        if has_error {
-            return None;
+        match (has_error, buf.capacity() == 0) {
+            (true, _) => None,
+            (false, true) => Some(Cow::Borrowed(text)),
+            (false, false) => Some(Cow::Owned(buf)),
         }
-        // FIXME: don't actually allocate for borrowed case
-        let res = if buf == text { Cow::Borrowed(text) } else { Cow::Owned(buf) };
-        Some(res)
     }
 
     pub fn quote_offsets(&self) -> Option<QuoteOffsets> {
diff --git a/crates/vfs/src/file_set.rs b/crates/vfs/src/file_set.rs
index 4aa2d6526..9093fbd97 100644
--- a/crates/vfs/src/file_set.rs
+++ b/crates/vfs/src/file_set.rs
@@ -158,53 +158,4 @@ impl fst::Automaton for PrefixOf<'_> {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn path_prefix() {
-        let mut file_set = FileSetConfig::builder();
-        file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo".into())]);
-        file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo/bar/baz".into())]);
-        let file_set = file_set.build();
-
-        let mut vfs = Vfs::default();
-        vfs.set_file_contents(
-            VfsPath::new_virtual_path("/foo/src/lib.rs".into()),
-            Some(Vec::new()),
-        );
-        vfs.set_file_contents(
-            VfsPath::new_virtual_path("/foo/src/bar/baz/lib.rs".into()),
-            Some(Vec::new()),
-        );
-        vfs.set_file_contents(
-            VfsPath::new_virtual_path("/foo/bar/baz/lib.rs".into()),
-            Some(Vec::new()),
-        );
-        vfs.set_file_contents(VfsPath::new_virtual_path("/quux/lib.rs".into()), Some(Vec::new()));
-
-        let partition = file_set.partition(&vfs).into_iter().map(|it| it.len()).collect::<Vec<_>>();
-        assert_eq!(partition, vec![2, 1, 1]);
-    }
-
-    #[test]
-    fn name_prefix() {
-        let mut file_set = FileSetConfig::builder();
-        file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo".into())]);
-        file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo-things".into())]);
-        let file_set = file_set.build();
-
-        let mut vfs = Vfs::default();
-        vfs.set_file_contents(
-            VfsPath::new_virtual_path("/foo/src/lib.rs".into()),
-            Some(Vec::new()),
-        );
-        vfs.set_file_contents(
-            VfsPath::new_virtual_path("/foo-things/src/lib.rs".into()),
-            Some(Vec::new()),
-        );
-
-        let partition = file_set.partition(&vfs).into_iter().map(|it| it.len()).collect::<Vec<_>>();
-        assert_eq!(partition, vec![1, 1, 0]);
-    }
-}
+mod tests;
diff --git a/crates/vfs/src/file_set/tests.rs b/crates/vfs/src/file_set/tests.rs
new file mode 100644
index 000000000..2146df185
--- /dev/null
+++ b/crates/vfs/src/file_set/tests.rs
@@ -0,0 +1,42 @@
+use super::*;
+
+#[test]
+fn path_prefix() {
+    let mut file_set = FileSetConfig::builder();
+    file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo".into())]);
+    file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo/bar/baz".into())]);
+    let file_set = file_set.build();
+
+    let mut vfs = Vfs::default();
+    vfs.set_file_contents(VfsPath::new_virtual_path("/foo/src/lib.rs".into()), Some(Vec::new()));
+    vfs.set_file_contents(
+        VfsPath::new_virtual_path("/foo/src/bar/baz/lib.rs".into()),
+        Some(Vec::new()),
+    );
+    vfs.set_file_contents(
+        VfsPath::new_virtual_path("/foo/bar/baz/lib.rs".into()),
+        Some(Vec::new()),
+    );
+    vfs.set_file_contents(VfsPath::new_virtual_path("/quux/lib.rs".into()), Some(Vec::new()));
+
+    let partition = file_set.partition(&vfs).into_iter().map(|it| it.len()).collect::<Vec<_>>();
+    assert_eq!(partition, vec![2, 1, 1]);
+}
+
+#[test]
+fn name_prefix() {
+    let mut file_set = FileSetConfig::builder();
+    file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo".into())]);
+    file_set.add_file_set(vec![VfsPath::new_virtual_path("/foo-things".into())]);
+    let file_set = file_set.build();
+
+    let mut vfs = Vfs::default();
+    vfs.set_file_contents(VfsPath::new_virtual_path("/foo/src/lib.rs".into()), Some(Vec::new()));
+    vfs.set_file_contents(
+        VfsPath::new_virtual_path("/foo-things/src/lib.rs".into()),
+        Some(Vec::new()),
+    );
+
+    let partition = file_set.partition(&vfs).into_iter().map(|it| it.len()).collect::<Vec<_>>();
+    assert_eq!(partition, vec![1, 1, 0]);
+}
diff --git a/crates/vfs/src/vfs_path.rs b/crates/vfs/src/vfs_path.rs
index 815697597..bd14911c9 100644
--- a/crates/vfs/src/vfs_path.rs
+++ b/crates/vfs/src/vfs_path.rs
@@ -311,35 +311,4 @@ impl VirtualPath {
 }
 
 #[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn virtual_path_extensions() {
-        assert_eq!(VirtualPath("/".to_string()).name_and_extension(), None);
-        assert_eq!(
-            VirtualPath("/directory".to_string()).name_and_extension(),
-            Some(("directory", None))
-        );
-        assert_eq!(
-            VirtualPath("/directory/".to_string()).name_and_extension(),
-            Some(("directory", None))
-        );
-        assert_eq!(
-            VirtualPath("/directory/file".to_string()).name_and_extension(),
-            Some(("file", None))
-        );
-        assert_eq!(
-            VirtualPath("/directory/.file".to_string()).name_and_extension(),
-            Some((".file", None))
-        );
-        assert_eq!(
-            VirtualPath("/directory/.file.rs".to_string()).name_and_extension(),
-            Some((".file", Some("rs")))
-        );
-        assert_eq!(
-            VirtualPath("/directory/file.rs".to_string()).name_and_extension(),
-            Some(("file", Some("rs")))
-        );
-    }
-}
+mod tests;
diff --git a/crates/vfs/src/vfs_path/tests.rs b/crates/vfs/src/vfs_path/tests.rs
new file mode 100644
index 000000000..510e021e8
--- /dev/null
+++ b/crates/vfs/src/vfs_path/tests.rs
@@ -0,0 +1,30 @@
+use super::*;
+
+#[test]
+fn virtual_path_extensions() {
+    assert_eq!(VirtualPath("/".to_string()).name_and_extension(), None);
+    assert_eq!(
+        VirtualPath("/directory".to_string()).name_and_extension(),
+        Some(("directory", None))
+    );
+    assert_eq!(
+        VirtualPath("/directory/".to_string()).name_and_extension(),
+        Some(("directory", None))
+    );
+    assert_eq!(
+        VirtualPath("/directory/file".to_string()).name_and_extension(),
+        Some(("file", None))
+    );
+    assert_eq!(
+        VirtualPath("/directory/.file".to_string()).name_and_extension(),
+        Some((".file", None))
+    );
+    assert_eq!(
+        VirtualPath("/directory/.file.rs".to_string()).name_and_extension(),
+        Some((".file", Some("rs")))
+    );
+    assert_eq!(
+        VirtualPath("/directory/file.rs".to_string()).name_and_extension(),
+        Some(("file", Some("rs")))
+    );
+}
diff --git a/docs/user/generated_diagnostic.adoc b/docs/user/generated_diagnostic.adoc
index 34c4f98a3..ec8581a03 100644
--- a/docs/user/generated_diagnostic.adoc
+++ b/docs/user/generated_diagnostic.adoc
@@ -17,6 +17,12 @@ This diagnostic is shown for code with inactive `#[cfg]` attributes.
 This diagnostic is triggered if item name doesn't follow https://doc.rust-lang.org/1.0.0/style/style/naming/README.html[Rust naming convention].
 
 
+=== macro-error
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/hir_def/src/diagnostics.rs#L167[diagnostics.rs]
+
+This diagnostic is shown for macro expansion errors.
+
+
 === mismatched-arg-count
 **Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/hir_ty/src/diagnostics.rs#L267[diagnostics.rs]
 
@@ -103,3 +109,11 @@ This diagnostic is triggered if rust-analyzer is unable to discover imported mod
 **Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/hir_def/src/diagnostics.rs#L18[diagnostics.rs]
 
 This diagnostic is triggered if rust-analyzer is unable to discover referred module.
+
+
+=== unresolved-proc-macro
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/hir_def/src/diagnostics.rs#L131[diagnostics.rs]
+
+This diagnostic is shown when a procedural macro can not be found. This usually means that
+procedural macro support is simply disabled (and hence is only a weak hint instead of an error),
+but can also indicate project setup problems.