53 files changed, 1348 insertions, 544 deletions

diff --git a/crates/ra_assists/src/assists/apply_demorgan.rs b/crates/ra_assists/src/assists/apply_demorgan.rs
new file mode 100644
index 000000000..5f2b0dd18
--- /dev/null
+++ b/crates/ra_assists/src/assists/apply_demorgan.rs
@@ -0,0 +1,102 @@
+//! This contains the functions associated with the demorgan assist.
+//! This assist transforms boolean expressions of the form `!a || !b` into
+//! `!(a && b)`.
+use hir::db::HirDatabase;
+use ra_syntax::ast::{self, AstNode};
+use ra_syntax::SyntaxNode;
+
+use crate::{Assist, AssistCtx, AssistId};
+
+/// Assist for applying demorgan's law
+///
+/// This transforms expressions of the form `!l || !r` into `!(l && r)`.
+/// This also works with `&&`. This assist can only be applied with the cursor
+/// on either `||` or `&&`, with both operands being a negation of some kind.
+/// This means something of the form `!x` or `x != y`.
+pub(crate) fn apply_demorgan(mut ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let expr = ctx.node_at_offset::<ast::BinExpr>()?;
+    let op = expr.op_kind()?;
+    let op_range = expr.op_token()?.text_range();
+    let opposite_op = opposite_logic_op(op)?;
+    let cursor_in_range = ctx.frange.range.is_subrange(&op_range);
+    if !cursor_in_range {
+        return None;
+    }
+    let lhs = expr.lhs()?.syntax().clone();
+    let lhs_range = lhs.text_range();
+    let rhs = expr.rhs()?.syntax().clone();
+    let rhs_range = rhs.text_range();
+    let not_lhs = undo_negation(lhs)?;
+    let not_rhs = undo_negation(rhs)?;
+
+    ctx.add_action(AssistId("apply_demorgan"), "apply demorgan's law", |edit| {
+        edit.target(op_range);
+        edit.replace(op_range, opposite_op);
+        edit.replace(lhs_range, format!("!({}", not_lhs));
+        edit.replace(rhs_range, format!("{})", not_rhs));
+    });
+    ctx.build()
+}
+
+// Return the opposite text for a given logical operator, if it makes sense
+fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
+    match kind {
+        ast::BinOp::BooleanOr => Some("&&"),
+        ast::BinOp::BooleanAnd => Some("||"),
+        _ => None,
+    }
+}
+
+// This function tries to undo unary negation, or inequality
+fn undo_negation(node: SyntaxNode) -> Option<String> {
+    match ast::Expr::cast(node)? {
+        ast::Expr::BinExpr(bin) => match bin.op_kind()? {
+            ast::BinOp::NegatedEqualityTest => {
+                let lhs = bin.lhs()?.syntax().text();
+                let rhs = bin.rhs()?.syntax().text();
+                Some(format!("{} == {}", lhs, rhs))
+            }
+            _ => None,
+        },
+        ast::Expr::PrefixExpr(pe) => match pe.op_kind()? {
+            ast::PrefixOp::Not => {
+                let child = pe.expr()?.syntax().text();
+                Some(String::from(child))
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use crate::helpers::{check_assist, check_assist_not_applicable};
+
+    #[test]
+    fn demorgan_turns_and_into_or() {
+        check_assist(apply_demorgan, "fn f() { !x &&<|> !x }", "fn f() { !(x ||<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_turns_or_into_and() {
+        check_assist(apply_demorgan, "fn f() { !x ||<|> !x }", "fn f() { !(x &&<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_removes_inequality() {
+        check_assist(apply_demorgan, "fn f() { x != x ||<|> !x }", "fn f() { !(x == x &&<|> x) }")
+    }
+
+    #[test]
+    fn demorgan_doesnt_apply_with_cursor_not_on_op() {
+        check_assist_not_applicable(apply_demorgan, "fn f() { <|> !x || !x }")
+    }
+
+    #[test]
+    fn demorgan_doesnt_apply_when_operands_arent_negated_already() {
+        check_assist_not_applicable(apply_demorgan, "fn f() { x ||<|> x }")
+    }
+}
diff --git a/crates/ra_assists/src/assists/split_import.rs b/crates/ra_assists/src/assists/split_import.rs
index 19d429daf..fe3e64af5 100644
--- a/crates/ra_assists/src/assists/split_import.rs
+++ b/crates/ra_assists/src/assists/split_import.rs
@@ -51,13 +51,13 @@ mod tests {
     fn split_import_works_with_trees() {
         check_assist(
             split_import,
-            "use algo:<|>:visitor::{Visitor, visit}",
-            "use algo::{<|>visitor::{Visitor, visit}}",
+            "use crate:<|>:db::{RootDatabase, FileSymbol}",
+            "use crate::{<|>db::{RootDatabase, FileSymbol}}",
         )
     }
 
     #[test]
     fn split_import_target() {
-        check_assist_target(split_import, "use algo::<|>visitor::{Visitor, visit}", "::");
+        check_assist_target(split_import, "use crate::<|>db::{RootDatabase, FileSymbol}", "::");
     }
 }
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 91b2a1dce..d2376c475 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -92,6 +92,7 @@ mod assists {
     mod add_derive;
     mod add_explicit_type;
     mod add_impl;
+    mod apply_demorgan;
     mod flip_comma;
     mod flip_binexpr;
     mod change_visibility;
@@ -113,6 +114,7 @@ mod assists {
             add_derive::add_derive,
             add_explicit_type::add_explicit_type,
             add_impl::add_impl,
+            apply_demorgan::apply_demorgan,
             change_visibility::change_visibility,
             fill_match_arms::fill_match_arms,
             merge_match_arms::merge_match_arms,
diff --git a/crates/ra_batch/src/lib.rs b/crates/ra_batch/src/lib.rs
index 939f72037..a5fc2a23e 100644
--- a/crates/ra_batch/src/lib.rs
+++ b/crates/ra_batch/src/lib.rs
@@ -7,7 +7,7 @@ use rustc_hash::FxHashMap;
 use crossbeam_channel::{unbounded, Receiver};
 use ra_db::{CrateGraph, FileId, SourceRootId};
 use ra_ide_api::{AnalysisChange, AnalysisHost, FeatureFlags};
-use ra_project_model::{PackageRoot, ProjectWorkspace};
+use ra_project_model::{get_rustc_cfg_options, PackageRoot, ProjectWorkspace};
 use ra_vfs::{RootEntry, Vfs, VfsChange, VfsTask, Watch};
 use ra_vfs_glob::RustPackageFilterBuilder;
 
@@ -41,11 +41,17 @@ pub fn load_cargo(root: &Path) -> Result<(AnalysisHost, FxHashMap<SourceRootId,
         sender,
         Watch(false),
     );
-    let (crate_graph, _crate_names) = ws.to_crate_graph(&mut |path: &Path| {
-        let vfs_file = vfs.load(path);
-        log::debug!("vfs file {:?} -> {:?}", path, vfs_file);
-        vfs_file.map(vfs_file_to_id)
-    });
+
+    // FIXME: cfg options?
+    let default_cfg_options =
+        get_rustc_cfg_options().atom("test".into()).atom("debug_assertion".into());
+
+    let (crate_graph, _crate_names) =
+        ws.to_crate_graph(&default_cfg_options, &mut |path: &Path| {
+            let vfs_file = vfs.load(path);
+            log::debug!("vfs file {:?} -> {:?}", path, vfs_file);
+            vfs_file.map(vfs_file_to_id)
+        });
     log::debug!("crate graph: {:?}", crate_graph);
 
     let source_roots = roots
diff --git a/crates/ra_cfg/Cargo.toml b/crates/ra_cfg/Cargo.toml
new file mode 100644
index 000000000..b28affc3a
--- /dev/null
+++ b/crates/ra_cfg/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+edition = "2018"
+name = "ra_cfg"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+
+[dependencies]
+rustc-hash = "1.0.1"
+
+ra_syntax = { path = "../ra_syntax" }
+tt = { path = "../ra_tt", package = "ra_tt" }
+
+[dev-dependencies]
+mbe = { path = "../ra_mbe", package = "ra_mbe" }
diff --git a/crates/ra_cfg/src/cfg_expr.rs b/crates/ra_cfg/src/cfg_expr.rs
new file mode 100644
index 000000000..39d71851c
--- /dev/null
+++ b/crates/ra_cfg/src/cfg_expr.rs
@@ -0,0 +1,132 @@
+//! The condition expression used in `#[cfg(..)]` attributes.
+//!
+//! See: https://doc.rust-lang.org/reference/conditional-compilation.html#conditional-compilation
+
+use std::slice::Iter as SliceIter;
+
+use ra_syntax::SmolStr;
+use tt::{Leaf, Subtree, TokenTree};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum CfgExpr {
+    Invalid,
+    Atom(SmolStr),
+    KeyValue { key: SmolStr, value: SmolStr },
+    All(Vec<CfgExpr>),
+    Any(Vec<CfgExpr>),
+    Not(Box<CfgExpr>),
+}
+
+impl CfgExpr {
+    /// Fold the cfg by querying all basic `Atom` and `KeyValue` predicates.
+    pub fn fold(&self, query: &dyn Fn(&SmolStr, Option<&SmolStr>) -> bool) -> Option<bool> {
+        match self {
+            CfgExpr::Invalid => None,
+            CfgExpr::Atom(name) => Some(query(name, None)),
+            CfgExpr::KeyValue { key, value } => Some(query(key, Some(value))),
+            CfgExpr::All(preds) => {
+                preds.iter().try_fold(true, |s, pred| Some(s && pred.fold(query)?))
+            }
+            CfgExpr::Any(preds) => {
+                preds.iter().try_fold(false, |s, pred| Some(s || pred.fold(query)?))
+            }
+            CfgExpr::Not(pred) => pred.fold(query).map(|s| !s),
+        }
+    }
+}
+
+pub fn parse_cfg(tt: &Subtree) -> CfgExpr {
+    next_cfg_expr(&mut tt.token_trees.iter()).unwrap_or(CfgExpr::Invalid)
+}
+
+fn next_cfg_expr(it: &mut SliceIter<tt::TokenTree>) -> Option<CfgExpr> {
+    let name = match it.next() {
+        None => return None,
+        Some(TokenTree::Leaf(Leaf::Ident(ident))) => ident.text.clone(),
+        Some(_) => return Some(CfgExpr::Invalid),
+    };
+
+    // Peek
+    let ret = match it.as_slice().first() {
+        Some(TokenTree::Leaf(Leaf::Punct(punct))) if punct.char == '=' => {
+            match it.as_slice().get(1) {
+                Some(TokenTree::Leaf(Leaf::Literal(literal))) => {
+                    it.next();
+                    it.next();
+                    // FIXME: escape? raw string?
+                    let value =
+                        SmolStr::new(literal.text.trim_start_matches('"').trim_end_matches('"'));
+                    CfgExpr::KeyValue { key: name, value }
+                }
+                _ => return Some(CfgExpr::Invalid),
+            }
+        }
+        Some(TokenTree::Subtree(subtree)) => {
+            it.next();
+            let mut sub_it = subtree.token_trees.iter();
+            let mut subs = std::iter::from_fn(|| next_cfg_expr(&mut sub_it)).collect();
+            match name.as_str() {
+                "all" => CfgExpr::All(subs),
+                "any" => CfgExpr::Any(subs),
+                "not" => CfgExpr::Not(Box::new(subs.pop().unwrap_or(CfgExpr::Invalid))),
+                _ => CfgExpr::Invalid,
+            }
+        }
+        _ => CfgExpr::Atom(name),
+    };
+
+    // Eat comma separator
+    if let Some(TokenTree::Leaf(Leaf::Punct(punct))) = it.as_slice().first() {
+        if punct.char == ',' {
+            it.next();
+        }
+    }
+    Some(ret)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use mbe::ast_to_token_tree;
+    use ra_syntax::ast::{self, AstNode};
+
+    fn assert_parse_result(input: &str, expected: CfgExpr) {
+        let source_file = ast::SourceFile::parse(input).ok().unwrap();
+        let tt = source_file.syntax().descendants().find_map(ast::TokenTree::cast).unwrap();
+        let (tt, _) = ast_to_token_tree(&tt).unwrap();
+        assert_eq!(parse_cfg(&tt), expected);
+    }
+
+    #[test]
+    fn test_cfg_expr_parser() {
+        assert_parse_result("#![cfg(foo)]", CfgExpr::Atom("foo".into()));
+        assert_parse_result("#![cfg(foo,)]", CfgExpr::Atom("foo".into()));
+        assert_parse_result(
+            "#![cfg(not(foo))]",
+            CfgExpr::Not(Box::new(CfgExpr::Atom("foo".into()))),
+        );
+        assert_parse_result("#![cfg(foo(bar))]", CfgExpr::Invalid);
+
+        // Only take the first
+        assert_parse_result(r#"#![cfg(foo, bar = "baz")]"#, CfgExpr::Atom("foo".into()));
+
+        assert_parse_result(
+            r#"#![cfg(all(foo, bar = "baz"))]"#,
+            CfgExpr::All(vec![
+                CfgExpr::Atom("foo".into()),
+                CfgExpr::KeyValue { key: "bar".into(), value: "baz".into() },
+            ]),
+        );
+
+        assert_parse_result(
+            r#"#![cfg(any(not(), all(), , bar = "baz",))]"#,
+            CfgExpr::Any(vec![
+                CfgExpr::Not(Box::new(CfgExpr::Invalid)),
+                CfgExpr::All(vec![]),
+                CfgExpr::Invalid,
+                CfgExpr::KeyValue { key: "bar".into(), value: "baz".into() },
+            ]),
+        );
+    }
+}
diff --git a/crates/ra_cfg/src/lib.rs b/crates/ra_cfg/src/lib.rs
new file mode 100644
index 000000000..e1c92fbba
--- /dev/null
+++ b/crates/ra_cfg/src/lib.rs
@@ -0,0 +1,61 @@
+//! ra_cfg defines conditional compiling options, `cfg` attibute parser and evaluator
+use std::iter::IntoIterator;
+
+use ra_syntax::SmolStr;
+use rustc_hash::FxHashSet;
+
+mod cfg_expr;
+
+pub use cfg_expr::{parse_cfg, CfgExpr};
+
+/// Configuration options used for conditional compilition on items with `cfg` attributes.
+/// We have two kind of options in different namespaces: atomic options like `unix`, and
+/// key-value options like `target_arch="x86"`.
+///
+/// Note that for key-value options, one key can have multiple values (but not none).
+/// `feature` is an example. We have both `feature="foo"` and `feature="bar"` if features
+/// `foo` and `bar` are both enabled. And here, we store key-value options as a set of tuple
+/// of key and value in `key_values`.
+///
+/// See: https://doc.rust-lang.org/reference/conditional-compilation.html#set-configuration-options
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct CfgOptions {
+    atoms: FxHashSet<SmolStr>,
+    key_values: FxHashSet<(SmolStr, SmolStr)>,
+}
+
+impl CfgOptions {
+    pub fn check(&self, cfg: &CfgExpr) -> Option<bool> {
+        cfg.fold(&|key, value| match value {
+            None => self.atoms.contains(key),
+            Some(value) => self.key_values.contains(&(key.clone(), value.clone())),
+        })
+    }
+
+    pub fn is_cfg_enabled(&self, attr: &tt::Subtree) -> Option<bool> {
+        self.check(&parse_cfg(attr))
+    }
+
+    pub fn atom(mut self, name: SmolStr) -> CfgOptions {
+        self.atoms.insert(name);
+        self
+    }
+
+    pub fn key_value(mut self, key: SmolStr, value: SmolStr) -> CfgOptions {
+        self.key_values.insert((key, value));
+        self
+    }
+
+    /// Shortcut to set features
+    pub fn features(mut self, iter: impl IntoIterator<Item = SmolStr>) -> CfgOptions {
+        for feat in iter {
+            self = self.key_value("feature".into(), feat);
+        }
+        self
+    }
+
+    pub fn remove_atom(mut self, name: &SmolStr) -> CfgOptions {
+        self.atoms.remove(name);
+        self
+    }
+}
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 2fac07bc5..c141f1a88 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -10,4 +10,5 @@ relative-path = "0.4.0"
 rustc-hash = "1.0"
 
 ra_syntax = { path = "../ra_syntax" }
+ra_cfg = { path = "../ra_cfg" }
 ra_prof = { path = "../ra_prof" }
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index 52f892891..23148096c 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -9,6 +9,7 @@
 use relative_path::{RelativePath, RelativePathBuf};
 use rustc_hash::FxHashMap;
 
+use ra_cfg::CfgOptions;
 use ra_syntax::SmolStr;
 use rustc_hash::FxHashSet;
 
@@ -109,11 +110,12 @@ struct CrateData {
     file_id: FileId,
     edition: Edition,
     dependencies: Vec<Dependency>,
+    cfg_options: CfgOptions,
 }
 
 impl CrateData {
-    fn new(file_id: FileId, edition: Edition) -> CrateData {
-        CrateData { file_id, edition, dependencies: Vec::new() }
+    fn new(file_id: FileId, edition: Edition, cfg_options: CfgOptions) -> CrateData {
+        CrateData { file_id, edition, dependencies: Vec::new(), cfg_options }
     }
 
     fn add_dep(&mut self, name: SmolStr, crate_id: CrateId) {
@@ -134,13 +136,22 @@ impl Dependency {
 }
 
 impl CrateGraph {
-    pub fn add_crate_root(&mut self, file_id: FileId, edition: Edition) -> CrateId {
+    pub fn add_crate_root(
+        &mut self,
+        file_id: FileId,
+        edition: Edition,
+        cfg_options: CfgOptions,
+    ) -> CrateId {
         let crate_id = CrateId(self.arena.len() as u32);
-        let prev = self.arena.insert(crate_id, CrateData::new(file_id, edition));
+        let prev = self.arena.insert(crate_id, CrateData::new(file_id, edition, cfg_options));
         assert!(prev.is_none());
         crate_id
     }
 
+    pub fn cfg_options(&self, crate_id: CrateId) -> &CfgOptions {
+        &self.arena[&crate_id].cfg_options
+    }
+
     pub fn add_dep(
         &mut self,
         from: CrateId,
@@ -221,14 +232,14 @@ impl CrateGraph {
 
 #[cfg(test)]
 mod tests {
-    use super::{CrateGraph, Edition::Edition2018, FileId, SmolStr};
+    use super::{CfgOptions, CrateGraph, Edition::Edition2018, FileId, SmolStr};
 
     #[test]
     fn it_should_panic_because_of_cycle_dependencies() {
         let mut graph = CrateGraph::default();
-        let crate1 = graph.add_crate_root(FileId(1u32), Edition2018);
-        let crate2 = graph.add_crate_root(FileId(2u32), Edition2018);
-        let crate3 = graph.add_crate_root(FileId(3u32), Edition2018);
+        let crate1 = graph.add_crate_root(FileId(1u32), Edition2018, CfgOptions::default());
+        let crate2 = graph.add_crate_root(FileId(2u32), Edition2018, CfgOptions::default());
+        let crate3 = graph.add_crate_root(FileId(3u32), Edition2018, CfgOptions::default());
         assert!(graph.add_dep(crate1, SmolStr::new("crate2"), crate2).is_ok());
         assert!(graph.add_dep(crate2, SmolStr::new("crate3"), crate3).is_ok());
         assert!(graph.add_dep(crate3, SmolStr::new("crate1"), crate1).is_err());
@@ -237,9 +248,9 @@ mod tests {
     #[test]
     fn it_works() {
         let mut graph = CrateGraph::default();
-        let crate1 = graph.add_crate_root(FileId(1u32), Edition2018);
-        let crate2 = graph.add_crate_root(FileId(2u32), Edition2018);
-        let crate3 = graph.add_crate_root(FileId(3u32), Edition2018);
+        let crate1 = graph.add_crate_root(FileId(1u32), Edition2018, CfgOptions::default());
+        let crate2 = graph.add_crate_root(FileId(2u32), Edition2018, CfgOptions::default());
+        let crate3 = graph.add_crate_root(FileId(3u32), Edition2018, CfgOptions::default());
         assert!(graph.add_dep(crate1, SmolStr::new("crate2"), crate2).is_ok());
         assert!(graph.add_dep(crate2, SmolStr::new("crate3"), crate3).is_ok());
     }
diff --git a/crates/ra_hir/Cargo.toml b/crates/ra_hir/Cargo.toml
index d9bed4dda..cc117f84d 100644
--- a/crates/ra_hir/Cargo.toml
+++ b/crates/ra_hir/Cargo.toml
@@ -15,6 +15,7 @@ once_cell = "1.0.1"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_arena = { path = "../ra_arena" }
+ra_cfg = { path = "../ra_cfg" }
 ra_db = { path = "../ra_db" }
 mbe = { path = "../ra_mbe", package = "ra_mbe" }
 tt = { path = "../ra_tt", package = "ra_tt" }
diff --git a/crates/ra_hir/src/attr.rs b/crates/ra_hir/src/attr.rs
new file mode 100644
index 000000000..f67e80bfd
--- /dev/null
+++ b/crates/ra_hir/src/attr.rs
@@ -0,0 +1,80 @@
+//! A higher level attributes based on TokenTree, with also some shortcuts.
+
+use std::sync::Arc;
+
+use mbe::ast_to_token_tree;
+use ra_cfg::CfgOptions;
+use ra_syntax::{
+    ast::{self, AstNode, AttrsOwner},
+    SmolStr,
+};
+use tt::Subtree;
+
+use crate::{db::AstDatabase, path::Path, HirFileId, Source};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct Attr {
+    pub(crate) path: Path,
+    pub(crate) input: Option<AttrInput>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AttrInput {
+    Literal(SmolStr),
+    TokenTree(Subtree),
+}
+
+impl Attr {
+    pub(crate) fn from_src(
+        Source { file_id, ast }: Source<ast::Attr>,
+        db: &impl AstDatabase,
+    ) -> Option<Attr> {
+        let path = Path::from_src(Source { file_id, ast: ast.path()? }, db)?;
+        let input = match ast.input() {
+            None => None,
+            Some(ast::AttrInput::Literal(lit)) => {
+                // FIXME: escape? raw string?
+                let value = lit.syntax().first_token()?.text().trim_matches('"').into();
+                Some(AttrInput::Literal(value))
+            }
+            Some(ast::AttrInput::TokenTree(tt)) => {
+                Some(AttrInput::TokenTree(ast_to_token_tree(&tt)?.0))
+            }
+        };
+
+        Some(Attr { path, input })
+    }
+
+    pub(crate) fn from_attrs_owner(
+        file_id: HirFileId,
+        owner: &dyn AttrsOwner,
+        db: &impl AstDatabase,
+    ) -> Option<Arc<[Attr]>> {
+        let mut attrs = owner.attrs().peekable();
+        if attrs.peek().is_none() {
+            // Avoid heap allocation
+            return None;
+        }
+        Some(attrs.flat_map(|ast| Attr::from_src(Source { file_id, ast }, db)).collect())
+    }
+
+    pub(crate) fn is_simple_atom(&self, name: &str) -> bool {
+        // FIXME: Avoid cloning
+        self.path.as_ident().map_or(false, |s| s.to_string() == name)
+    }
+
+    pub(crate) fn as_cfg(&self) -> Option<&Subtree> {
+        if self.is_simple_atom("cfg") {
+            match &self.input {
+                Some(AttrInput::TokenTree(subtree)) => Some(subtree),
+                _ => None,
+            }
+        } else {
+            None
+        }
+    }
+
+    pub(crate) fn is_cfg_enabled(&self, cfg_options: &CfgOptions) -> Option<bool> {
+        cfg_options.is_cfg_enabled(self.as_cfg()?)
+    }
+}
diff --git a/crates/ra_hir/src/impl_block.rs b/crates/ra_hir/src/impl_block.rs
index 8cf74ddc7..55dfc393b 100644
--- a/crates/ra_hir/src/impl_block.rs
+++ b/crates/ra_hir/src/impl_block.rs
@@ -4,12 +4,14 @@ use rustc_hash::FxHashMap;
 use std::sync::Arc;
 
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
+use ra_cfg::CfgOptions;
 use ra_syntax::{
     ast::{self, AstNode},
     AstPtr,
 };
 
 use crate::{
+    attr::Attr,
     code_model::{Module, ModuleSource},
     db::{AstDatabase, DefDatabase, HirDatabase},
     generics::HasGenericParams,
@@ -176,6 +178,7 @@ pub struct ModuleImplBlocks {
 impl ModuleImplBlocks {
     fn collect(
         db: &(impl DefDatabase + AstDatabase),
+        cfg_options: &CfgOptions,
         module: Module,
         source_map: &mut ImplSourceMap,
     ) -> Self {
@@ -188,11 +191,11 @@ impl ModuleImplBlocks {
         let src = m.module.definition_source(db);
         match &src.ast {
             ModuleSource::SourceFile(node) => {
-                m.collect_from_item_owner(db, source_map, node, src.file_id)
+                m.collect_from_item_owner(db, cfg_options, source_map, node, src.file_id)
             }
             ModuleSource::Module(node) => {
                 let item_list = node.item_list().expect("inline module should have item list");
-                m.collect_from_item_owner(db, source_map, &item_list, src.file_id)
+                m.collect_from_item_owner(db, cfg_options, source_map, &item_list, src.file_id)
             }
         };
         m
@@ -201,6 +204,7 @@ impl ModuleImplBlocks {
     fn collect_from_item_owner(
         &mut self,
         db: &(impl DefDatabase + AstDatabase),
+        cfg_options: &CfgOptions,
         source_map: &mut ImplSourceMap,
         owner: &dyn ast::ModuleItemOwner,
         file_id: HirFileId,
@@ -208,6 +212,13 @@ impl ModuleImplBlocks {
         for item in owner.items_with_macros() {
             match item {
                 ast::ItemOrMacro::Item(ast::ModuleItem::ImplBlock(impl_block_ast)) => {
+                    let attrs = Attr::from_attrs_owner(file_id, &impl_block_ast, db);
+                    if attrs.map_or(false, |attrs| {
+                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
+                    }) {
+                        continue;
+                    }
+
                     let impl_block = ImplData::from_ast(db, file_id, self.module, &impl_block_ast);
                     let id = self.impls.alloc(impl_block);
                     for &impl_item in &self.impls[id].items {
@@ -218,6 +229,13 @@ impl ModuleImplBlocks {
                 }
                 ast::ItemOrMacro::Item(_) => (),
                 ast::ItemOrMacro::Macro(macro_call) => {
+                    let attrs = Attr::from_attrs_owner(file_id, &macro_call, db);
+                    if attrs.map_or(false, |attrs| {
+                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
+                    }) {
+                        continue;
+                    }
+
                     //FIXME: we should really cut down on the boilerplate required to process a macro
                     let ast_id = db.ast_id_map(file_id).ast_id(&macro_call).with_file_id(file_id);
                     if let Some(path) = macro_call
@@ -231,7 +249,13 @@ impl ModuleImplBlocks {
                             if let Some(item_list) =
                                 db.parse_or_expand(file_id).and_then(ast::MacroItems::cast)
                             {
-                                self.collect_from_item_owner(db, source_map, &item_list, file_id)
+                                self.collect_from_item_owner(
+                                    db,
+                                    cfg_options,
+                                    source_map,
+                                    &item_list,
+                                    file_id,
+                                )
                             }
                         }
                     }
@@ -246,8 +270,10 @@ pub(crate) fn impls_in_module_with_source_map_query(
     module: Module,
 ) -> (Arc<ModuleImplBlocks>, Arc<ImplSourceMap>) {
     let mut source_map = ImplSourceMap::default();
+    let crate_graph = db.crate_graph();
+    let cfg_options = crate_graph.cfg_options(module.krate.crate_id());
 
-    let result = ModuleImplBlocks::collect(db, module, &mut source_map);
+    let result = ModuleImplBlocks::collect(db, cfg_options, module, &mut source_map);
     (Arc::new(result), Arc::new(source_map))
 }
 
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 00031deba..4340e9d34 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -44,6 +44,7 @@ mod traits;
 mod type_alias;
 mod type_ref;
 mod ty;
+mod attr;
 mod impl_block;
 mod expr;
 mod lang_item;
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 50feb98fb..f750986b8 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -3,6 +3,7 @@
 use std::{panic, sync::Arc};
 
 use parking_lot::Mutex;
+use ra_cfg::CfgOptions;
 use ra_db::{
     salsa, CrateGraph, CrateId, Edition, FileId, FilePosition, SourceDatabase, SourceRoot,
     SourceRootId,
@@ -74,13 +75,13 @@ impl MockDatabase {
     pub fn set_crate_graph_from_fixture(&mut self, graph: CrateGraphFixture) {
         let mut ids = FxHashMap::default();
         let mut crate_graph = CrateGraph::default();
-        for (crate_name, (crate_root, edition, _)) in graph.0.iter() {
+        for (crate_name, (crate_root, edition, cfg_options, _)) in graph.0.iter() {
             let crate_root = self.file_id_of(&crate_root);
-            let crate_id = crate_graph.add_crate_root(crate_root, *edition);
+            let crate_id = crate_graph.add_crate_root(crate_root, *edition, cfg_options.clone());
             Arc::make_mut(&mut self.crate_names).insert(crate_id, crate_name.clone());
             ids.insert(crate_name, crate_id);
         }
-        for (crate_name, (_, _, deps)) in graph.0.iter() {
+        for (crate_name, (_, _, _, deps)) in graph.0.iter() {
             let from = ids[crate_name];
             for dep in deps {
                 let to = ids[dep];
@@ -184,7 +185,7 @@ impl MockDatabase {
 
         if is_crate_root {
             let mut crate_graph = CrateGraph::default();
-            crate_graph.add_crate_root(file_id, Edition::Edition2018);
+            crate_graph.add_crate_root(file_id, Edition::Edition2018, CfgOptions::default());
             self.set_crate_graph(Arc::new(crate_graph));
         }
         file_id
@@ -268,19 +269,27 @@ impl MockDatabase {
 }
 
 #[derive(Default)]
-pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, Vec<String>))>);
+pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, CfgOptions, Vec<String>))>);
 
 #[macro_export]
 macro_rules! crate_graph {
-    ($($crate_name:literal: ($crate_path:literal, $($edition:literal,)? [$($dep:literal),*]),)*) => {{
+    ($(
+        $crate_name:literal: (
+            $crate_path:literal,
+            $($edition:literal,)?
+            [$($dep:literal),*]
+            $(,$cfg:expr)?
+        ),
+    )*) => {{
         let mut res = $crate::mock::CrateGraphFixture::default();
         $(
             #[allow(unused_mut, unused_assignments)]
             let mut edition = ra_db::Edition::Edition2018;
             $(edition = ra_db::Edition::from_string($edition);)?
+            let cfg_options = { ::ra_cfg::CfgOptions::default() $(; $cfg)? };
             res.0.push((
                 $crate_name.to_string(),
-                ($crate_path.to_string(), edition, vec![$($dep.to_string()),*])
+                ($crate_path.to_string(), edition, cfg_options, vec![$($dep.to_string()),*])
             ));
         )*
         res
diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index a568fdabd..cef2dc9d2 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -1,5 +1,6 @@
 //! FIXME: write short doc here
 
+use ra_cfg::CfgOptions;
 use ra_db::FileId;
 use ra_syntax::{ast, SmolStr};
 use rustc_hash::FxHashMap;
@@ -35,6 +36,9 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         }
     }
 
+    let crate_graph = db.crate_graph();
+    let cfg_options = crate_graph.cfg_options(def_map.krate().crate_id());
+
     let mut collector = DefCollector {
         db,
         def_map,
@@ -42,6 +46,7 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         unresolved_imports: Vec::new(),
         unexpanded_macros: Vec::new(),
         macro_stack_monitor: MacroStackMonitor::default(),
+        cfg_options,
     };
     collector.collect();
     collector.finish()
@@ -76,8 +81,8 @@ impl MacroStackMonitor {
 }
 
 /// Walks the tree of module recursively
-struct DefCollector<DB> {
-    db: DB,
+struct DefCollector<'a, DB> {
+    db: &'a DB,
     def_map: CrateDefMap,
     glob_imports: FxHashMap<CrateModuleId, Vec<(CrateModuleId, raw::ImportId)>>,
     unresolved_imports: Vec<(CrateModuleId, raw::ImportId, raw::ImportData)>,
@@ -86,9 +91,11 @@ struct DefCollector<DB> {
     /// Some macro use `$tt:tt which mean we have to handle the macro perfectly
     /// To prevent stack overflow, we add a deep counter here for prevent that.
     macro_stack_monitor: MacroStackMonitor,
+
+    cfg_options: &'a CfgOptions,
 }
 
-impl<'a, DB> DefCollector<&'a DB>
+impl<DB> DefCollector<'_, DB>
 where
     DB: DefDatabase,
 {
@@ -506,7 +513,7 @@ struct ModCollector<'a, D> {
     parent_module: Option<ParentModule<'a>>,
 }
 
-impl<DB> ModCollector<'_, &'_ mut DefCollector<&'_ DB>>
+impl<DB> ModCollector<'_, &'_ mut DefCollector<'_, DB>>
 where
     DB: DefDatabase,
 {
@@ -523,24 +530,27 @@ where
         // `#[macro_use] extern crate` is hoisted to imports macros before collecting
         // any other items.
         for item in items {
-            if let raw::RawItem::Import(import_id) = *item {
-                let import = self.raw_items[import_id].clone();
-                if import.is_extern_crate && import.is_macro_use {
-                    self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+            if self.is_cfg_enabled(&item.attrs) {
+                if let raw::RawItemKind::Import(import_id) = item.kind {
+                    let import = self.raw_items[import_id].clone();
+                    if import.is_extern_crate && import.is_macro_use {
+                        self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+                    }
                 }
             }
         }
 
         for item in items {
-            match *item {
-                raw::RawItem::Module(m) => self.collect_module(&self.raw_items[m]),
-                raw::RawItem::Import(import_id) => self.def_collector.unresolved_imports.push((
-                    self.module_id,
-                    import_id,
-                    self.raw_items[import_id].clone(),
-                )),
-                raw::RawItem::Def(def) => self.define_def(&self.raw_items[def]),
-                raw::RawItem::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+            if self.is_cfg_enabled(&item.attrs) {
+                match item.kind {
+                    raw::RawItemKind::Module(m) => self.collect_module(&self.raw_items[m]),
+                    raw::RawItemKind::Import(import_id) => self
+                        .def_collector
+                        .unresolved_imports
+                        .push((self.module_id, import_id, self.raw_items[import_id].clone())),
+                    raw::RawItemKind::Def(def) => self.define_def(&self.raw_items[def]),
+                    raw::RawItemKind::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+                }
             }
         }
     }
@@ -703,6 +713,14 @@ where
             self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_);
         }
     }
+
+    fn is_cfg_enabled(&self, attrs: &raw::Attrs) -> bool {
+        attrs.as_ref().map_or(true, |attrs| {
+            attrs
+                .iter()
+                .all(|attr| attr.is_cfg_enabled(&self.def_collector.cfg_options) != Some(false))
+        })
+    }
 }
 
 fn is_macro_rules(path: &Path) -> bool {
@@ -730,6 +748,7 @@ mod tests {
             unresolved_imports: Vec::new(),
             unexpanded_macros: Vec::new(),
             macro_stack_monitor: monitor,
+            cfg_options: &CfgOptions::default(),
         };
         collector.collect();
         collector.finish()
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index 606bd1a95..623b343c4 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir/src/nameres/raw.rs
@@ -10,6 +10,7 @@ use ra_syntax::{
 use test_utils::tested_by;
 
 use crate::{
+    attr::Attr,
     db::{AstDatabase, DefDatabase},
     AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path, Source,
 };
@@ -119,8 +120,17 @@ impl Index<Macro> for RawItems {
     }
 }
 
+// Avoid heap allocation on items without attributes.
+pub(super) type Attrs = Option<Arc<[Attr]>>;
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub(super) struct RawItem {
+    pub(super) attrs: Attrs,
+    pub(super) kind: RawItemKind,
+}
+
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub(super) enum RawItem {
+pub(super) enum RawItemKind {
     Module(Module),
     Import(ImportId),
     Def(Def),
@@ -215,6 +225,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
     }
 
     fn add_item(&mut self, current_module: Option<Module>, item: ast::ModuleItem) {
+        let attrs = self.parse_attrs(&item);
         let (kind, name) = match item {
             ast::ModuleItem::Module(module) => {
                 self.add_module(current_module, module);
@@ -263,7 +274,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         if let Some(name) = name {
             let name = name.as_name();
             let def = self.raw_items.defs.alloc(DefData { name, kind });
-            self.push_item(current_module, RawItem::Def(def))
+            self.push_item(current_module, attrs, RawItemKind::Def(def));
         }
     }
 
@@ -272,8 +283,10 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
             Some(it) => it.as_name(),
             None => return,
         };
+        let attrs = self.parse_attrs(&module);
 
         let ast_id = self.source_ast_id_map.ast_id(&module);
+        // FIXME: cfg_attr
         let is_macro_use = module.has_atom_attr("macro_use");
         if module.has_semi() {
             let attr_path = extract_mod_path_attribute(&module);
@@ -283,7 +296,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 attr_path,
                 is_macro_use,
             });
-            self.push_item(current_module, RawItem::Module(item));
+            self.push_item(current_module, attrs, RawItemKind::Module(item));
             return;
         }
 
@@ -297,14 +310,16 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 is_macro_use,
             });
             self.process_module(Some(item), item_list);
-            self.push_item(current_module, RawItem::Module(item));
+            self.push_item(current_module, attrs, RawItemKind::Module(item));
             return;
         }
         tested_by!(name_res_works_for_broken_modules);
     }
 
     fn add_use_item(&mut self, current_module: Option<Module>, use_item: ast::UseItem) {
+        // FIXME: cfg_attr
         let is_prelude = use_item.has_atom_attr("prelude_import");
+        let attrs = self.parse_attrs(&use_item);
 
         Path::expand_use_item(
             Source { ast: use_item, file_id: self.file_id },
@@ -318,7 +333,12 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                     is_extern_crate: false,
                     is_macro_use: false,
                 };
-                self.push_import(current_module, import_data, Either::A(AstPtr::new(use_tree)));
+                self.push_import(
+                    current_module,
+                    attrs.clone(),
+                    import_data,
+                    Either::A(AstPtr::new(use_tree)),
+                );
             },
         )
     }
@@ -331,6 +351,8 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         if let Some(name_ref) = extern_crate.name_ref() {
             let path = Path::from_name_ref(&name_ref);
             let alias = extern_crate.alias().and_then(|a| a.name()).map(|it| it.as_name());
+            let attrs = self.parse_attrs(&extern_crate);
+            // FIXME: cfg_attr
             let is_macro_use = extern_crate.has_atom_attr("macro_use");
             let import_data = ImportData {
                 path,
@@ -340,11 +362,17 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 is_extern_crate: true,
                 is_macro_use,
             };
-            self.push_import(current_module, import_data, Either::B(AstPtr::new(&extern_crate)));
+            self.push_import(
+                current_module,
+                attrs,
+                import_data,
+                Either::B(AstPtr::new(&extern_crate)),
+            );
         }
     }
 
     fn add_macro(&mut self, current_module: Option<Module>, m: ast::MacroCall) {
+        let attrs = self.parse_attrs(&m);
         let path = match m
             .path()
             .and_then(|path| Path::from_src(Source { ast: path, file_id: self.file_id }, self.db))
@@ -355,24 +383,26 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
 
         let name = m.name().map(|it| it.as_name());
         let ast_id = self.source_ast_id_map.ast_id(&m);
+        // FIXME: cfg_attr
         let export = m.attrs().filter_map(|x| x.simple_name()).any(|name| name == "macro_export");
 
         let m = self.raw_items.macros.alloc(MacroData { ast_id, path, name, export });
-        self.push_item(current_module, RawItem::Macro(m));
+        self.push_item(current_module, attrs, RawItemKind::Macro(m));
     }
 
     fn push_import(
         &mut self,
         current_module: Option<Module>,
+        attrs: Attrs,
         data: ImportData,
         source: ImportSourcePtr,
     ) {
         let import = self.raw_items.imports.alloc(data);
         self.source_map.insert(import, source);
-        self.push_item(current_module, RawItem::Import(import))
+        self.push_item(current_module, attrs, RawItemKind::Import(import))
     }
 
-    fn push_item(&mut self, current_module: Option<Module>, item: RawItem) {
+    fn push_item(&mut self, current_module: Option<Module>, attrs: Attrs, kind: RawItemKind) {
         match current_module {
             Some(module) => match &mut self.raw_items.modules[module] {
                 ModuleData::Definition { items, .. } => items,
@@ -380,7 +410,11 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
             },
             None => &mut self.raw_items.items,
         }
-        .push(item)
+        .push(RawItem { attrs, kind })
+    }
+
+    fn parse_attrs(&self, item: &impl ast::AttrsOwner) -> Attrs {
+        Attr::from_attrs_owner(self.file_id, item, self.db)
     }
 }
 
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index bc4b47b70..34dd79574 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -7,6 +7,7 @@ mod mod_resolution;
 use std::sync::Arc;
 
 use insta::assert_snapshot;
+use ra_cfg::CfgOptions;
 use ra_db::SourceDatabase;
 use test_utils::covers;
 
@@ -507,3 +508,72 @@ fn values_dont_shadow_extern_crates() {
         ⋮foo: v
     "###);
 }
+
+#[test]
+fn cfg_not_test() {
+    let map = def_map_with_crate_graph(
+        r#"
+        //- /main.rs
+        use {Foo, Bar, Baz};
+        //- /lib.rs
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            #[cfg(test)]
+            pub struct Foo;
+            #[cfg(not(test))]
+            pub struct Bar;
+            #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+            pub struct Baz;
+        }
+        "#,
+        crate_graph! {
+            "main": ("/main.rs", ["std"]),
+            "std": ("/lib.rs", []),
+        },
+    );
+
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: t v
+        ⋮Baz: _
+        ⋮Foo: _
+    "###);
+}
+
+#[test]
+fn cfg_test() {
+    let map = def_map_with_crate_graph(
+        r#"
+        //- /main.rs
+        use {Foo, Bar, Baz};
+        //- /lib.rs
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            #[cfg(test)]
+            pub struct Foo;
+            #[cfg(not(test))]
+            pub struct Bar;
+            #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+            pub struct Baz;
+        }
+        "#,
+        crate_graph! {
+            "main": ("/main.rs", ["std"]),
+            "std": ("/lib.rs", [], CfgOptions::default()
+                .atom("test".into())
+                .key_value("feature".into(), "foo".into())
+                .key_value("feature".into(), "bar".into())
+                .key_value("opt".into(), "42".into())
+            ),
+        },
+    );
+
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: _
+        ⋮Baz: t v
+        ⋮Foo: t v
+    "###);
+}
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 66f63ca24..25dad81eb 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -3,6 +3,7 @@ use std::sync::Arc;
 
 use insta::assert_snapshot;
 
+use ra_cfg::CfgOptions;
 use ra_db::{salsa::Database, FilePosition, SourceDatabase};
 use ra_syntax::{
     algo,
@@ -24,6 +25,50 @@ mod never_type;
 mod coercion;
 
 #[test]
+fn cfg_impl_block() {
+    let (mut db, pos) = MockDatabase::with_position(
+        r#"
+//- /main.rs
+use foo::S as T;
+struct S;
+
+#[cfg(test)]
+impl S {
+    fn foo1(&self) -> i32 { 0 }
+}
+
+#[cfg(not(test))]
+impl S {
+    fn foo2(&self) -> i32 { 0 }
+}
+
+fn test() {
+    let t = (S.foo1(), S.foo2(), T.foo3(), T.foo4());
+    t<|>;
+}
+
+//- /foo.rs
+struct S;
+
+#[cfg(not(test))]
+impl S {
+    fn foo3(&self) -> i32 { 0 }
+}
+
+#[cfg(test)]
+impl S {
+    fn foo4(&self) -> i32 { 0 }
+}
+"#,
+    );
+    db.set_crate_graph_from_fixture(crate_graph! {
+        "main": ("/main.rs", ["foo"], CfgOptions::default().atom("test".into())),
+        "foo": ("/foo.rs", []),
+    });
+    assert_eq!("(i32, {unknown}, i32, {unknown})", type_at_pos(&db, pos));
+}
+
+#[test]
 fn infer_await() {
     let (mut db, pos) = MockDatabase::with_position(
         r#"
diff --git a/crates/ra_ide_api/Cargo.toml b/crates/ra_ide_api/Cargo.toml
index 6bbf9d5dd..f919a2d61 100644
--- a/crates/ra_ide_api/Cargo.toml
+++ b/crates/ra_ide_api/Cargo.toml
@@ -23,6 +23,7 @@ rand = { version = "0.7.0", features = ["small_rng"] }
 ra_syntax = { path = "../ra_syntax" }
 ra_text_edit = { path = "../ra_text_edit" }
 ra_db = { path = "../ra_db" }
+ra_cfg = { path = "../ra_cfg" }
 ra_fmt = { path = "../ra_fmt" }
 ra_prof = { path = "../ra_prof" }
 hir = { path = "../ra_hir", package = "ra_hir" }
diff --git a/crates/ra_ide_api/src/completion/complete_fn_param.rs b/crates/ra_ide_api/src/completion/complete_fn_param.rs
index 844a63f6c..3e936e3ec 100644
--- a/crates/ra_ide_api/src/completion/complete_fn_param.rs
+++ b/crates/ra_ide_api/src/completion/complete_fn_param.rs
@@ -1,9 +1,6 @@
 //! FIXME: write short doc here
 
-use ra_syntax::{
-    algo::visit::{visitor_ctx, VisitorCtx},
-    ast, AstNode,
-};
+use ra_syntax::{ast, match_ast, AstNode};
 use rustc_hash::FxHashMap;
 
 use crate::completion::{CompletionContext, CompletionItem, CompletionKind, Completions};
@@ -19,10 +16,13 @@ pub(super) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
 
     let mut params = FxHashMap::default();
     for node in ctx.token.parent().ancestors() {
-        let _ = visitor_ctx(&mut params)
-            .visit::<ast::SourceFile, _>(process)
-            .visit::<ast::ItemList, _>(process)
-            .accept(&node);
+        match_ast! {
+            match node {
+                ast::SourceFile(it) => { process(it, &mut params) },
+                ast::ItemList(it) => { process(it, &mut params) },
+                _ => (),
+            }
+        }
     }
     params
         .into_iter()
diff --git a/crates/ra_ide_api/src/completion/complete_keyword.rs b/crates/ra_ide_api/src/completion/complete_keyword.rs
index 3f121d45c..48c688a08 100644
--- a/crates/ra_ide_api/src/completion/complete_keyword.rs
+++ b/crates/ra_ide_api/src/completion/complete_keyword.rs
@@ -1,9 +1,8 @@
 //! FIXME: write short doc here
 
 use ra_syntax::{
-    algo::visit::{visitor, Visitor},
     ast::{self, LoopBodyOwner},
-    AstNode,
+    match_ast, AstNode,
     SyntaxKind::*,
     SyntaxToken,
 };
@@ -84,12 +83,15 @@ fn is_in_loop_body(leaf: &SyntaxToken) -> bool {
         if node.kind() == FN_DEF || node.kind() == LAMBDA_EXPR {
             break;
         }
-        let loop_body = visitor()
-            .visit::<ast::ForExpr, _>(|it| it.loop_body())
-            .visit::<ast::WhileExpr, _>(|it| it.loop_body())
-            .visit::<ast::LoopExpr, _>(|it| it.loop_body())
-            .accept(&node);
-        if let Some(Some(body)) = loop_body {
+        let loop_body = match_ast! {
+            match node {
+                ast::ForExpr(it) => { it.loop_body() },
+                ast::WhileExpr(it) => { it.loop_body() },
+                ast::LoopExpr(it) => { it.loop_body() },
+                _ => None,
+            }
+        };
+        if let Some(body) = loop_body {
             if leaf.text_range().is_subrange(&body.syntax().text_range()) {
                 return true;
             }
diff --git a/crates/ra_ide_api/src/display/navigation_target.rs b/crates/ra_ide_api/src/display/navigation_target.rs
index 60ae802c0..d0b1a8a2a 100644
--- a/crates/ra_ide_api/src/display/navigation_target.rs
+++ b/crates/ra_ide_api/src/display/navigation_target.rs
@@ -3,9 +3,8 @@
 use hir::{AssocItem, FieldSource, HasSource, ModuleSource};
 use ra_db::{FileId, SourceDatabase};
 use ra_syntax::{
-    algo::visit::{visitor, Visitor},
     ast::{self, DocCommentsOwner},
-    AstNode, AstPtr, SmolStr,
+    match_ast, AstNode, AstPtr, SmolStr,
     SyntaxKind::{self, NAME},
     SyntaxNode, TextRange,
 };
@@ -308,19 +307,22 @@ pub(crate) fn docs_from_symbol(db: &RootDatabase, symbol: &FileSymbol) -> Option
     let parse = db.parse(symbol.file_id);
     let node = symbol.ptr.to_node(parse.tree().syntax());
 
-    visitor()
-        .visit(|it: ast::FnDef| it.doc_comment_text())
-        .visit(|it: ast::StructDef| it.doc_comment_text())
-        .visit(|it: ast::EnumDef| it.doc_comment_text())
-        .visit(|it: ast::TraitDef| it.doc_comment_text())
-        .visit(|it: ast::Module| it.doc_comment_text())
-        .visit(|it: ast::TypeAliasDef| it.doc_comment_text())
-        .visit(|it: ast::ConstDef| it.doc_comment_text())
-        .visit(|it: ast::StaticDef| it.doc_comment_text())
-        .visit(|it: ast::RecordFieldDef| it.doc_comment_text())
-        .visit(|it: ast::EnumVariant| it.doc_comment_text())
-        .visit(|it: ast::MacroCall| it.doc_comment_text())
-        .accept(&node)?
+    match_ast! {
+        match node {
+            ast::FnDef(it) => { it.doc_comment_text() },
+            ast::StructDef(it) => { it.doc_comment_text() },
+            ast::EnumDef(it) => { it.doc_comment_text() },
+            ast::TraitDef(it) => { it.doc_comment_text() },
+            ast::Module(it) => { it.doc_comment_text() },
+            ast::TypeAliasDef(it) => { it.doc_comment_text() },
+            ast::ConstDef(it) => { it.doc_comment_text() },
+            ast::StaticDef(it) => { it.doc_comment_text() },
+            ast::RecordFieldDef(it) => { it.doc_comment_text() },
+            ast::EnumVariant(it) => { it.doc_comment_text() },
+            ast::MacroCall(it) => { it.doc_comment_text() },
+            _ => None,
+        }
+    }
 }
 
 /// Get a description of a symbol.
@@ -330,16 +332,19 @@ pub(crate) fn description_from_symbol(db: &RootDatabase, symbol: &FileSymbol) ->
     let parse = db.parse(symbol.file_id);
     let node = symbol.ptr.to_node(parse.tree().syntax());
 
-    visitor()
-        .visit(|node: ast::FnDef| node.short_label())
-        .visit(|node: ast::StructDef| node.short_label())
-        .visit(|node: ast::EnumDef| node.short_label())
-        .visit(|node: ast::TraitDef| node.short_label())
-        .visit(|node: ast::Module| node.short_label())
-        .visit(|node: ast::TypeAliasDef| node.short_label())
-        .visit(|node: ast::ConstDef| node.short_label())
-        .visit(|node: ast::StaticDef| node.short_label())
-        .visit(|node: ast::RecordFieldDef| node.short_label())
-        .visit(|node: ast::EnumVariant| node.short_label())
-        .accept(&node)?
+    match_ast! {
+        match node {
+            ast::FnDef(it) => { it.short_label() },
+            ast::StructDef(it) => { it.short_label() },
+            ast::EnumDef(it) => { it.short_label() },
+            ast::TraitDef(it) => { it.short_label() },
+            ast::Module(it) => { it.short_label() },
+            ast::TypeAliasDef(it) => { it.short_label() },
+            ast::ConstDef(it) => { it.short_label() },
+            ast::StaticDef(it) => { it.short_label() },
+            ast::RecordFieldDef(it) => { it.short_label() },
+            ast::EnumVariant(it) => { it.short_label() },
+            _ => None,
+        }
+    }
 }
diff --git a/crates/ra_ide_api/src/display/structure.rs b/crates/ra_ide_api/src/display/structure.rs
index 8815df747..ddd8b7b20 100644
--- a/crates/ra_ide_api/src/display/structure.rs
+++ b/crates/ra_ide_api/src/display/structure.rs
@@ -3,9 +3,8 @@
 use crate::TextRange;
 
 use ra_syntax::{
-    algo::visit::{visitor, Visitor},
     ast::{self, AttrsOwner, NameOwner, TypeAscriptionOwner, TypeParamsOwner},
-    AstNode, SourceFile, SyntaxKind, SyntaxNode, WalkEvent,
+    match_ast, AstNode, SourceFile, SyntaxKind, SyntaxNode, WalkEvent,
 };
 
 #[derive(Debug, Clone)]
@@ -101,63 +100,66 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
         })
     }
 
-    visitor()
-        .visit(|fn_def: ast::FnDef| {
-            let mut detail = String::from("fn");
-            if let Some(type_param_list) = fn_def.type_param_list() {
-                collapse_ws(type_param_list.syntax(), &mut detail);
-            }
-            if let Some(param_list) = fn_def.param_list() {
-                collapse_ws(param_list.syntax(), &mut detail);
-            }
-            if let Some(ret_type) = fn_def.ret_type() {
-                detail.push_str(" ");
-                collapse_ws(ret_type.syntax(), &mut detail);
-            }
-
-            decl_with_detail(fn_def, Some(detail))
-        })
-        .visit(decl::<ast::StructDef>)
-        .visit(decl::<ast::EnumDef>)
-        .visit(decl::<ast::EnumVariant>)
-        .visit(decl::<ast::TraitDef>)
-        .visit(decl::<ast::Module>)
-        .visit(|td: ast::TypeAliasDef| {
-            let ty = td.type_ref();
-            decl_with_type_ref(td, ty)
-        })
-        .visit(decl_with_ascription::<ast::RecordFieldDef>)
-        .visit(decl_with_ascription::<ast::ConstDef>)
-        .visit(decl_with_ascription::<ast::StaticDef>)
-        .visit(|im: ast::ImplBlock| {
-            let target_type = im.target_type()?;
-            let target_trait = im.target_trait();
-            let label = match target_trait {
-                None => format!("impl {}", target_type.syntax().text()),
-                Some(t) => {
-                    format!("impl {} for {}", t.syntax().text(), target_type.syntax().text(),)
+    match_ast! {
+        match node {
+            ast::FnDef(it) => {
+                let mut detail = String::from("fn");
+                if let Some(type_param_list) = it.type_param_list() {
+                    collapse_ws(type_param_list.syntax(), &mut detail);
+                }
+                if let Some(param_list) = it.param_list() {
+                    collapse_ws(param_list.syntax(), &mut detail);
+                }
+                if let Some(ret_type) = it.ret_type() {
+                    detail.push_str(" ");
+                    collapse_ws(ret_type.syntax(), &mut detail);
                 }
-            };
 
-            let node = StructureNode {
-                parent: None,
-                label,
-                navigation_range: target_type.syntax().text_range(),
-                node_range: im.syntax().text_range(),
-                kind: im.syntax().kind(),
-                detail: None,
-                deprecated: false,
-            };
-            Some(node)
-        })
-        .visit(|mc: ast::MacroCall| {
-            let first_token = mc.syntax().first_token().unwrap();
-            if first_token.text().as_str() != "macro_rules" {
-                return None;
-            }
-            decl(mc)
-        })
-        .accept(&node)?
+                decl_with_detail(it, Some(detail))
+            },
+            ast::StructDef(it) => { decl(it) },
+            ast::EnumDef(it) => { decl(it) },
+            ast::EnumVariant(it) => { decl(it) },
+            ast::TraitDef(it) => { decl(it) },
+            ast::Module(it) => { decl(it) },
+            ast::TypeAliasDef(it) => {
+                let ty = it.type_ref();
+                decl_with_type_ref(it, ty)
+            },
+            ast::RecordFieldDef(it) => { decl_with_ascription(it) },
+            ast::ConstDef(it) => { decl_with_ascription(it) },
+            ast::StaticDef(it) => { decl_with_ascription(it) },
+            ast::ImplBlock(it) => {
+                let target_type = it.target_type()?;
+                let target_trait = it.target_trait();
+                let label = match target_trait {
+                    None => format!("impl {}", target_type.syntax().text()),
+                    Some(t) => {
+                        format!("impl {} for {}", t.syntax().text(), target_type.syntax().text(),)
+                    }
+                };
+
+                let node = StructureNode {
+                    parent: None,
+                    label,
+                    navigation_range: target_type.syntax().text_range(),
+                    node_range: it.syntax().text_range(),
+                    kind: it.syntax().kind(),
+                    detail: None,
+                    deprecated: false,
+                };
+                Some(node)
+            },
+            ast::MacroCall(it) => {
+                let first_token = it.syntax().first_token().unwrap();
+                if first_token.text().as_str() != "macro_rules" {
+                    return None;
+                }
+                decl(it)
+            },
+            _ => None,
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ra_ide_api/src/goto_definition.rs b/crates/ra_ide_api/src/goto_definition.rs
index 567d4a674..41a88314f 100644
--- a/crates/ra_ide_api/src/goto_definition.rs
+++ b/crates/ra_ide_api/src/goto_definition.rs
@@ -2,12 +2,9 @@
 
 use ra_db::{FileId, SourceDatabase};
 use ra_syntax::{
-    algo::{
-        find_node_at_offset,
-        visit::{visitor, Visitor},
-    },
+    algo::find_node_at_offset,
     ast::{self, DocCommentsOwner},
-    AstNode, SyntaxNode,
+    match_ast, AstNode, SyntaxNode,
 };
 
 use crate::{
@@ -114,91 +111,99 @@ pub(crate) fn name_definition(
 }
 
 fn named_target(file_id: FileId, node: &SyntaxNode) -> Option<NavigationTarget> {
-    visitor()
-        .visit(|node: ast::StructDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::EnumDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::EnumVariant| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::FnDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::TypeAliasDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::ConstDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::StaticDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::TraitDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::RecordFieldDef| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::Module| {
-            NavigationTarget::from_named(
-                file_id,
-                &node,
-                node.doc_comment_text(),
-                node.short_label(),
-            )
-        })
-        .visit(|node: ast::MacroCall| {
-            NavigationTarget::from_named(file_id, &node, node.doc_comment_text(), None)
-        })
-        .accept(node)
+    match_ast! {
+        match node {
+            ast::StructDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::EnumDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::EnumVariant(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::FnDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::TypeAliasDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::ConstDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::StaticDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::TraitDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::RecordFieldDef(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::Module(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    it.short_label(),
+                ))
+            },
+            ast::MacroCall(it) => {
+                Some(NavigationTarget::from_named(
+                    file_id,
+                    &it,
+                    it.doc_comment_text(),
+                    None,
+                ))
+            },
+            _ => None,
+        }
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 200b57679..24b161c5c 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -3,12 +3,9 @@
 use hir::{Adt, HasSource, HirDisplay};
 use ra_db::SourceDatabase;
 use ra_syntax::{
-    algo::{
-        ancestors_at_offset, find_covering_element, find_node_at_offset,
-        visit::{visitor, Visitor},
-    },
+    algo::{ancestors_at_offset, find_covering_element, find_node_at_offset},
     ast::{self, DocCommentsOwner},
-    AstNode,
+    match_ast, AstNode,
 };
 
 use crate::{
@@ -178,37 +175,45 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         }
     } else if let Some(name) = find_node_at_offset::<ast::Name>(file.syntax(), position.offset) {
         if let Some(parent) = name.syntax().parent() {
-            let text = visitor()
-                .visit(|node: ast::StructDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::EnumDef| hover_text(node.doc_comment_text(), node.short_label()))
-                .visit(|node: ast::EnumVariant| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::FnDef| hover_text(node.doc_comment_text(), node.short_label()))
-                .visit(|node: ast::TypeAliasDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::ConstDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::StaticDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::TraitDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::RecordFieldDef| {
-                    hover_text(node.doc_comment_text(), node.short_label())
-                })
-                .visit(|node: ast::Module| hover_text(node.doc_comment_text(), node.short_label()))
-                .visit(|node: ast::MacroCall| hover_text(node.doc_comment_text(), None))
-                .accept(&parent);
-
-            if let Some(text) = text {
-                res.extend(text);
-            }
+            let text = match_ast! {
+                match parent {
+                    ast::StructDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::EnumDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::EnumVariant(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::FnDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::TypeAliasDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::ConstDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::StaticDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::TraitDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::RecordFieldDef(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::Module(it) => {
+                        hover_text(it.doc_comment_text(), it.short_label())
+                    },
+                    ast::MacroCall(it) => {
+                        hover_text(it.doc_comment_text(), None)
+                    },
+                    _ => None,
+                }
+            };
+            res.extend(text);
         }
 
         if !res.is_empty() && range.is_none() {
diff --git a/crates/ra_ide_api/src/inlay_hints.rs b/crates/ra_ide_api/src/inlay_hints.rs
index 9b45575f8..f1c0dc164 100644
--- a/crates/ra_ide_api/src/inlay_hints.rs
+++ b/crates/ra_ide_api/src/inlay_hints.rs
@@ -3,9 +3,8 @@
 use crate::{db::RootDatabase, FileId};
 use hir::{HirDisplay, SourceAnalyzer, Ty};
 use ra_syntax::{
-    algo::visit::{visitor, Visitor},
     ast::{self, AstNode, TypeAscriptionOwner},
-    SmolStr, SourceFile, SyntaxKind, SyntaxNode, TextRange,
+    match_ast, SmolStr, SourceFile, SyntaxKind, SyntaxNode, TextRange,
 };
 
 #[derive(Debug, PartialEq, Eq)]
@@ -33,55 +32,58 @@ fn get_inlay_hints(
     file_id: FileId,
     node: &SyntaxNode,
 ) -> Option<Vec<InlayHint>> {
-    visitor()
-        .visit(|let_statement: ast::LetStmt| {
-            if let_statement.ascribed_type().is_some() {
-                return None;
-            }
-            let pat = let_statement.pat()?;
-            let analyzer = SourceAnalyzer::new(db, file_id, let_statement.syntax(), None);
-            Some(get_pat_type_hints(db, &analyzer, pat, false))
-        })
-        .visit(|closure_parameter: ast::LambdaExpr| {
-            let analyzer = SourceAnalyzer::new(db, file_id, closure_parameter.syntax(), None);
-            closure_parameter.param_list().map(|param_list| {
-                param_list
-                    .params()
-                    .filter(|closure_param| closure_param.ascribed_type().is_none())
-                    .filter_map(|closure_param| closure_param.pat())
-                    .map(|root_pat| get_pat_type_hints(db, &analyzer, root_pat, false))
-                    .flatten()
-                    .collect()
-            })
-        })
-        .visit(|for_expression: ast::ForExpr| {
-            let pat = for_expression.pat()?;
-            let analyzer = SourceAnalyzer::new(db, file_id, for_expression.syntax(), None);
-            Some(get_pat_type_hints(db, &analyzer, pat, false))
-        })
-        .visit(|if_expr: ast::IfExpr| {
-            let pat = if_expr.condition()?.pat()?;
-            let analyzer = SourceAnalyzer::new(db, file_id, if_expr.syntax(), None);
-            Some(get_pat_type_hints(db, &analyzer, pat, true))
-        })
-        .visit(|while_expr: ast::WhileExpr| {
-            let pat = while_expr.condition()?.pat()?;
-            let analyzer = SourceAnalyzer::new(db, file_id, while_expr.syntax(), None);
-            Some(get_pat_type_hints(db, &analyzer, pat, true))
-        })
-        .visit(|match_arm_list: ast::MatchArmList| {
-            let analyzer = SourceAnalyzer::new(db, file_id, match_arm_list.syntax(), None);
-            Some(
-                match_arm_list
-                    .arms()
-                    .map(|match_arm| match_arm.pats())
-                    .flatten()
-                    .map(|root_pat| get_pat_type_hints(db, &analyzer, root_pat, true))
-                    .flatten()
-                    .collect(),
-            )
-        })
-        .accept(&node)?
+    match_ast! {
+        match node {
+            ast::LetStmt(it) => {
+                if it.ascribed_type().is_some() {
+                    return None;
+                }
+                let pat = it.pat()?;
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                Some(get_pat_type_hints(db, &analyzer, pat, false))
+            },
+            ast::LambdaExpr(it) => {
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                it.param_list().map(|param_list| {
+                    param_list
+                        .params()
+                        .filter(|closure_param| closure_param.ascribed_type().is_none())
+                        .filter_map(|closure_param| closure_param.pat())
+                        .map(|root_pat| get_pat_type_hints(db, &analyzer, root_pat, false))
+                        .flatten()
+                        .collect()
+                })
+            },
+            ast::ForExpr(it) => {
+                let pat = it.pat()?;
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                Some(get_pat_type_hints(db, &analyzer, pat, false))
+            },
+            ast::IfExpr(it) => {
+                let pat = it.condition()?.pat()?;
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                Some(get_pat_type_hints(db, &analyzer, pat, true))
+            },
+            ast::WhileExpr(it) => {
+                let pat = it.condition()?.pat()?;
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                Some(get_pat_type_hints(db, &analyzer, pat, true))
+            },
+            ast::MatchArmList(it) => {
+                let analyzer = SourceAnalyzer::new(db, file_id, it.syntax(), None);
+                Some(
+                    it
+                        .arms()
+                        .map(|match_arm| match_arm.pats())
+                        .flatten()
+                        .map(|root_pat| get_pat_type_hints(db, &analyzer, root_pat, true))
+                        .flatten()
+                        .collect(),
+                )
+            },
+            _ => None,
+        }
+    }
 }
 
 fn get_pat_type_hints(
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index 44d1ec77b..24f1b91f6 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -49,6 +49,7 @@ mod test_utils;
 
 use std::sync::Arc;
 
+use ra_cfg::CfgOptions;
 use ra_db::{
     salsa::{self, ParallelDatabase},
     CheckCanceled, SourceDatabase,
@@ -322,7 +323,10 @@ impl Analysis {
         change.add_root(source_root, true);
         let mut crate_graph = CrateGraph::default();
         let file_id = FileId(0);
-        crate_graph.add_crate_root(file_id, Edition::Edition2018);
+        // FIXME: cfg options
+        // Default to enable test for single file.
+        let cfg_options = CfgOptions::default().atom("test".into());
+        crate_graph.add_crate_root(file_id, Edition::Edition2018, cfg_options);
         change.add_file(source_root, file_id, "main.rs".into(), Arc::new(text));
         change.set_crate_graph(crate_graph);
         host.apply_change(change);
diff --git a/crates/ra_ide_api/src/mock_analysis.rs b/crates/ra_ide_api/src/mock_analysis.rs
index 16870c7ae..80b71894c 100644
--- a/crates/ra_ide_api/src/mock_analysis.rs
+++ b/crates/ra_ide_api/src/mock_analysis.rs
@@ -2,6 +2,7 @@
 
 use std::sync::Arc;
 
+use ra_cfg::CfgOptions;
 use relative_path::RelativePathBuf;
 use test_utils::{extract_offset, extract_range, parse_fixture, CURSOR_MARKER};
 
@@ -93,10 +94,11 @@ impl MockAnalysis {
             assert!(path.starts_with('/'));
             let path = RelativePathBuf::from_path(&path[1..]).unwrap();
             let file_id = FileId(i as u32 + 1);
+            let cfg_options = CfgOptions::default();
             if path == "/lib.rs" || path == "/main.rs" {
-                root_crate = Some(crate_graph.add_crate_root(file_id, Edition2018));
+                root_crate = Some(crate_graph.add_crate_root(file_id, Edition2018, cfg_options));
             } else if path.ends_with("/lib.rs") {
-                let other_crate = crate_graph.add_crate_root(file_id, Edition2018);
+                let other_crate = crate_graph.add_crate_root(file_id, Edition2018, cfg_options);
                 let crate_name = path.parent().unwrap().file_name().unwrap();
                 if let Some(root_crate) = root_crate {
                     crate_graph.add_dep(root_crate, crate_name.into(), other_crate).unwrap();
diff --git a/crates/ra_ide_api/src/parent_module.rs b/crates/ra_ide_api/src/parent_module.rs
index c85f1d0d0..566509849 100644
--- a/crates/ra_ide_api/src/parent_module.rs
+++ b/crates/ra_ide_api/src/parent_module.rs
@@ -41,6 +41,7 @@ mod tests {
         AnalysisChange, CrateGraph,
         Edition::Edition2018,
     };
+    use ra_cfg::CfgOptions;
 
     #[test]
     fn test_resolve_parent_module() {
@@ -88,7 +89,7 @@ mod tests {
         assert!(host.analysis().crate_for(mod_file).unwrap().is_empty());
 
         let mut crate_graph = CrateGraph::default();
-        let crate_id = crate_graph.add_crate_root(root_file, Edition2018);
+        let crate_id = crate_graph.add_crate_root(root_file, Edition2018, CfgOptions::default());
         let mut change = AnalysisChange::new();
         change.set_crate_graph(crate_graph);
         host.apply_change(change);
diff --git a/crates/ra_ide_api/src/symbol_index.rs b/crates/ra_ide_api/src/symbol_index.rs
index 02cdfbc60..797e9926f 100644
--- a/crates/ra_ide_api/src/symbol_index.rs
+++ b/crates/ra_ide_api/src/symbol_index.rs
@@ -32,9 +32,8 @@ use ra_db::{
     SourceDatabase, SourceRootId,
 };
 use ra_syntax::{
-    algo::visit::{visitor, Visitor},
     ast::{self, NameOwner},
-    AstNode, Parse, SmolStr, SourceFile,
+    match_ast, AstNode, Parse, SmolStr, SourceFile,
     SyntaxKind::{self, *},
     SyntaxNode, SyntaxNodePtr, TextRange, WalkEvent,
 };
@@ -306,16 +305,19 @@ fn to_symbol(node: &SyntaxNode) -> Option<(SmolStr, SyntaxNodePtr, TextRange)> {
 
         Some((name, ptr, name_range))
     }
-    visitor()
-        .visit(decl::<ast::FnDef>)
-        .visit(decl::<ast::StructDef>)
-        .visit(decl::<ast::EnumDef>)
-        .visit(decl::<ast::TraitDef>)
-        .visit(decl::<ast::Module>)
-        .visit(decl::<ast::TypeAliasDef>)
-        .visit(decl::<ast::ConstDef>)
-        .visit(decl::<ast::StaticDef>)
-        .accept(node)?
+    match_ast! {
+        match node {
+            ast::FnDef(it) => { decl(it) },
+            ast::StructDef(it) => { decl(it) },
+            ast::EnumDef(it) => { decl(it) },
+            ast::TraitDef(it) => { decl(it) },
+            ast::Module(it) => { decl(it) },
+            ast::TypeAliasDef(it) => { decl(it) },
+            ast::ConstDef(it) => { decl(it) },
+            ast::StaticDef(it) => { decl(it) },
+            _ => None,
+        }
+    }
 }
 
 fn to_file_symbol(node: &SyntaxNode, file_id: FileId) -> Option<FileSymbol> {
diff --git a/crates/ra_lsp_server/Cargo.toml b/crates/ra_lsp_server/Cargo.toml
index 677d81835..aedc55a95 100644
--- a/crates/ra_lsp_server/Cargo.toml
+++ b/crates/ra_lsp_server/Cargo.toml
@@ -19,6 +19,7 @@ jod-thread = "0.1.0"
 ra_vfs = "0.4.0"
 ra_syntax = { path = "../ra_syntax" }
 ra_db = { path = "../ra_db" }
+ra_cfg = { path = "../ra_cfg" }
 ra_text_edit = { path = "../ra_text_edit" }
 ra_ide_api = { path = "../ra_ide_api" }
 lsp-server = "0.2.0"
diff --git a/crates/ra_lsp_server/src/world.rs b/crates/ra_lsp_server/src/world.rs
index b55046ec9..27da751ab 100644
--- a/crates/ra_lsp_server/src/world.rs
+++ b/crates/ra_lsp_server/src/world.rs
@@ -13,7 +13,7 @@ use ra_ide_api::{
     Analysis, AnalysisChange, AnalysisHost, CrateGraph, FeatureFlags, FileId, LibraryData,
     SourceRootId,
 };
-use ra_project_model::ProjectWorkspace;
+use ra_project_model::{get_rustc_cfg_options, ProjectWorkspace};
 use ra_vfs::{LineEndings, RootEntry, Vfs, VfsChange, VfsFile, VfsRoot, VfsTask, Watch};
 use ra_vfs_glob::{Glob, RustPackageFilterBuilder};
 use relative_path::RelativePathBuf;
@@ -97,6 +97,10 @@ impl WorldState {
             change.set_debug_root_path(SourceRootId(r.0), vfs_root_path.display().to_string());
         }
 
+        // FIXME: Read default cfgs from config
+        let default_cfg_options =
+            get_rustc_cfg_options().atom("test".into()).atom("debug_assertion".into());
+
         // Create crate graph from all the workspaces
         let mut crate_graph = CrateGraph::default();
         let mut load = |path: &std::path::Path| {
@@ -104,7 +108,7 @@ impl WorldState {
             vfs_file.map(|f| FileId(f.0))
         };
         for ws in workspaces.iter() {
-            let (graph, crate_names) = ws.to_crate_graph(&mut load);
+            let (graph, crate_names) = ws.to_crate_graph(&default_cfg_options, &mut load);
             let shift = crate_graph.extend(graph);
             for (crate_id, name) in crate_names {
                 change.set_debug_crate_name(crate_id.shift(shift), name)
diff --git a/crates/ra_lsp_server/tests/heavy_tests/main.rs b/crates/ra_lsp_server/tests/heavy_tests/main.rs
index 152681062..2ba82ab05 100644
--- a/crates/ra_lsp_server/tests/heavy_tests/main.rs
+++ b/crates/ra_lsp_server/tests/heavy_tests/main.rs
@@ -286,7 +286,13 @@ fn test_missing_module_code_action_in_json_project() {
 
     let project = json!({
         "roots": [path],
-        "crates": [ { "root_module": path.join("src/lib.rs"), "deps": [], "edition": "2015" } ]
+        "crates": [ {
+            "root_module": path.join("src/lib.rs"),
+            "deps": [],
+            "edition": "2015",
+            "atom_cfgs": [],
+            "key_value_cfgs": {}
+        } ]
     });
 
     let code = format!(
diff --git a/crates/ra_parser/src/grammar/expressions.rs b/crates/ra_parser/src/grammar/expressions.rs
index c2a2060eb..45f2e3de4 100644
--- a/crates/ra_parser/src/grammar/expressions.rs
+++ b/crates/ra_parser/src/grammar/expressions.rs
@@ -344,7 +344,13 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
             // }
             //
             let (lhs, blocklike) = atom::atom_expr(p, r)?;
-            return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block())));
+            return Some(postfix_expr(
+                p,
+                lhs,
+                blocklike,
+                !(r.prefer_stmt && blocklike.is_block()),
+                r.forbid_structs,
+            ));
         }
     };
     // parse the interior of the unary expression
@@ -360,6 +366,7 @@ fn postfix_expr(
     // `while true {break}; ();`
     mut block_like: BlockLike,
     mut allow_calls: bool,
+    forbid_structs: bool,
 ) -> (CompletedMarker, BlockLike) {
     loop {
         lhs = match p.current() {
@@ -373,7 +380,7 @@ fn postfix_expr(
             // }
             T!['('] if allow_calls => call_expr(p, lhs),
             T!['['] if allow_calls => index_expr(p, lhs),
-            T![.] => match postfix_dot_expr(p, lhs) {
+            T![.] => match postfix_dot_expr(p, lhs, forbid_structs) {
                 Ok(it) => it,
                 Err(it) => {
                     lhs = it;
@@ -391,6 +398,7 @@ fn postfix_expr(
     fn postfix_dot_expr(
         p: &mut Parser,
         lhs: CompletedMarker,
+        forbid_structs: bool,
     ) -> Result<CompletedMarker, CompletedMarker> {
         assert!(p.at(T![.]));
         if p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth_at(2, T![::])) {
@@ -411,10 +419,17 @@ fn postfix_expr(
         }
 
         // test postfix_range
-        // fn foo() { let x = 1..; }
-        for &(op, la) in [(T![..=], 3), (T![..], 2)].iter() {
+        // fn foo() {
+        //     let x = 1..;
+        //     match 1.. { _ => () };
+        //     match a.b()..S { _ => () };
+        // }
+        for &(op, la) in &[(T![..=], 3), (T![..], 2)] {
             if p.at(op) {
-                return if EXPR_FIRST.contains(p.nth(la)) {
+                let next_token = p.nth(la);
+                let has_trailing_expression =
+                    !(forbid_structs && next_token == T!['{']) && EXPR_FIRST.contains(next_token);
+                return if has_trailing_expression {
                     Err(lhs)
                 } else {
                     let m = lhs.precede(p);
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index a52bdb3ea..7454005c4 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -121,11 +121,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
             //        break;
             //    }
             // }
-            if r.forbid_structs {
-                return None;
-            } else {
-                block_expr(p, None)
-            }
+            block_expr(p, None)
         }
         T![return] => return_expr(p),
         T![continue] => continue_expr(p),
@@ -261,6 +257,7 @@ fn lambda_expr(p: &mut Parser) -> CompletedMarker {
 //     if true {} else {};
 //     if true {} else if false {} else {};
 //     if S {};
+//     if { true } { } else { };
 // }
 fn if_expr(p: &mut Parser) -> CompletedMarker {
     assert!(p.at(T![if]));
@@ -309,6 +306,7 @@ fn loop_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
 // fn foo() {
 //     while true {};
 //     while let Some(x) = it.next() {};
+//     while { true } {};
 // }
 fn while_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
     assert!(p.at(T![while]));
@@ -356,6 +354,8 @@ fn cond(p: &mut Parser) {
 // fn foo() {
 //     match () { };
 //     match S {};
+//     match { } { _ => () };
+//     match { S {} } {};
 // }
 fn match_expr(p: &mut Parser) -> CompletedMarker {
     assert!(p.at(T![match]));
diff --git a/crates/ra_project_model/Cargo.toml b/crates/ra_project_model/Cargo.toml
index ae6b91aa6..a65100031 100644
--- a/crates/ra_project_model/Cargo.toml
+++ b/crates/ra_project_model/Cargo.toml
@@ -12,6 +12,7 @@ cargo_metadata = "0.8.2"
 
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
+ra_cfg = { path = "../ra_cfg" }
 
 serde = { version = "1.0.89", features = ["derive"] }
 serde_json = "1.0.39"
diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 805eaa178..28dadea9d 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -39,6 +39,7 @@ struct PackageData {
     is_member: bool,
     dependencies: Vec<PackageDependency>,
     edition: Edition,
+    features: Vec<String>,
 }
 
 #[derive(Debug, Clone)]
@@ -91,6 +92,9 @@ impl Package {
     pub fn edition(self, ws: &CargoWorkspace) -> Edition {
         ws.packages[self].edition
     }
+    pub fn features(self, ws: &CargoWorkspace) -> &[String] {
+        &ws.packages[self].features
+    }
     pub fn targets<'a>(self, ws: &'a CargoWorkspace) -> impl Iterator<Item = Target> + 'a {
         ws.packages[self].targets.iter().cloned()
     }
@@ -144,6 +148,7 @@ impl CargoWorkspace {
                 is_member,
                 edition: Edition::from_string(&meta_pkg.edition),
                 dependencies: Vec::new(),
+                features: Vec::new(),
             });
             let pkg_data = &mut packages[pkg];
             pkg_by_id.insert(meta_pkg.id.clone(), pkg);
@@ -164,6 +169,7 @@ impl CargoWorkspace {
                 let dep = PackageDependency { name: dep_node.name, pkg: pkg_by_id[&dep_node.pkg] };
                 packages[source].dependencies.push(dep);
             }
+            packages[source].features.extend(node.features);
         }
 
         Ok(CargoWorkspace { packages, targets, workspace_root: meta.workspace_root })
diff --git a/crates/ra_project_model/src/json_project.rs b/crates/ra_project_model/src/json_project.rs
index 54ddca2cb..1bacb1d09 100644
--- a/crates/ra_project_model/src/json_project.rs
+++ b/crates/ra_project_model/src/json_project.rs
@@ -2,6 +2,7 @@
 
 use std::path::PathBuf;
 
+use rustc_hash::{FxHashMap, FxHashSet};
 use serde::Deserialize;
 
 /// A root points to the directory which contains Rust crates. rust-analyzer watches all files in
@@ -19,6 +20,8 @@ pub struct Crate {
     pub(crate) root_module: PathBuf,
     pub(crate) edition: Edition,
     pub(crate) deps: Vec<Dep>,
+    pub(crate) atom_cfgs: FxHashSet<String>,
+    pub(crate) key_value_cfgs: FxHashMap<String, String>,
 }
 
 #[derive(Clone, Copy, Debug, Deserialize)]
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 5d3078598..640a5ebd3 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -9,8 +9,10 @@ use std::{
     fs::File,
     io::BufReader,
     path::{Path, PathBuf},
+    process::Command,
 };
 
+use ra_cfg::CfgOptions;
 use ra_db::{CrateGraph, CrateId, Edition, FileId};
 use rustc_hash::FxHashMap;
 use serde_json::from_reader;
@@ -117,6 +119,7 @@ impl ProjectWorkspace {
 
     pub fn to_crate_graph(
         &self,
+        default_cfg_options: &CfgOptions,
         load: &mut dyn FnMut(&Path) -> Option<FileId>,
     ) -> (CrateGraph, FxHashMap<CrateId, String>) {
         let mut crate_graph = CrateGraph::default();
@@ -131,7 +134,17 @@ impl ProjectWorkspace {
                             json_project::Edition::Edition2015 => Edition::Edition2015,
                             json_project::Edition::Edition2018 => Edition::Edition2018,
                         };
-                        crates.insert(crate_id, crate_graph.add_crate_root(file_id, edition));
+                        let mut cfg_options = default_cfg_options.clone();
+                        for name in &krate.atom_cfgs {
+                            cfg_options = cfg_options.atom(name.into());
+                        }
+                        for (key, value) in &krate.key_value_cfgs {
+                            cfg_options = cfg_options.key_value(key.into(), value.into());
+                        }
+                        crates.insert(
+                            crate_id,
+                            crate_graph.add_crate_root(file_id, edition, cfg_options),
+                        );
                     }
                 }
 
@@ -157,7 +170,10 @@ impl ProjectWorkspace {
                 let mut sysroot_crates = FxHashMap::default();
                 for krate in sysroot.crates() {
                     if let Some(file_id) = load(krate.root(&sysroot)) {
-                        let crate_id = crate_graph.add_crate_root(file_id, Edition::Edition2018);
+                        // Crates from sysroot have `cfg(test)` disabled
+                        let cfg_options = default_cfg_options.clone().remove_atom(&"test".into());
+                        let crate_id =
+                            crate_graph.add_crate_root(file_id, Edition::Edition2018, cfg_options);
                         sysroot_crates.insert(krate, crate_id);
                         names.insert(crate_id, krate.name(&sysroot).to_string());
                     }
@@ -186,7 +202,11 @@ impl ProjectWorkspace {
                         let root = tgt.root(&cargo);
                         if let Some(file_id) = load(root) {
                             let edition = pkg.edition(&cargo);
-                            let crate_id = crate_graph.add_crate_root(file_id, edition);
+                            let cfg_options = default_cfg_options
+                                .clone()
+                                .features(pkg.features(&cargo).iter().map(Into::into));
+                            let crate_id =
+                                crate_graph.add_crate_root(file_id, edition, cfg_options);
                             names.insert(crate_id, pkg.name(&cargo).to_string());
                             if tgt.kind(&cargo) == TargetKind::Lib {
                                 lib_tgt = Some(crate_id);
@@ -286,3 +306,32 @@ fn find_cargo_toml(path: &Path) -> Result<PathBuf> {
     }
     Err(format!("can't find Cargo.toml at {}", path.display()))?
 }
+
+pub fn get_rustc_cfg_options() -> CfgOptions {
+    let mut cfg_options = CfgOptions::default();
+
+    match (|| -> Result<_> {
+        // `cfg(test)` and `cfg(debug_assertion)` are handled outside, so we suppress them here.
+        let output = Command::new("rustc").args(&["--print", "cfg", "-O"]).output()?;
+        if !output.status.success() {
+            Err("failed to get rustc cfgs")?;
+        }
+        Ok(String::from_utf8(output.stdout)?)
+    })() {
+        Ok(rustc_cfgs) => {
+            for line in rustc_cfgs.lines() {
+                match line.find('=') {
+                    None => cfg_options = cfg_options.atom(line.into()),
+                    Some(pos) => {
+                        let key = &line[..pos];
+                        let value = line[pos + 1..].trim_matches('"');
+                        cfg_options = cfg_options.key_value(key.into(), value.into());
+                    }
+                }
+            }
+        }
+        Err(e) => log::error!("failed to get rustc cfgs: {}", e),
+    }
+
+    cfg_options
+}
diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
index d55534ede..7cfea70f9 100644
--- a/crates/ra_syntax/src/algo.rs
+++ b/crates/ra_syntax/src/algo.rs
@@ -1,7 +1,5 @@
 //! FIXME: write short doc here
 
-pub mod visit;
-
 use std::ops::RangeInclusive;
 
 use itertools::Itertools;
diff --git a/crates/ra_syntax/src/algo/visit.rs b/crates/ra_syntax/src/algo/visit.rs
deleted file mode 100644
index 4df275ba4..000000000
--- a/crates/ra_syntax/src/algo/visit.rs
+++ /dev/null
@@ -1,112 +0,0 @@
-//! FIXME: write short doc here
-
-use crate::{AstNode, SyntaxNode};
-
-use std::marker::PhantomData;
-
-pub fn visitor<'a, T>() -> impl Visitor<'a, Output = T> {
-    EmptyVisitor { ph: PhantomData }
-}
-
-pub fn visitor_ctx<'a, T, C>(ctx: C) -> impl VisitorCtx<'a, Output = T, Ctx = C> {
-    EmptyVisitorCtx { ph: PhantomData, ctx }
-}
-
-pub trait Visitor<'a>: Sized {
-    type Output;
-    fn accept(self, node: &'a SyntaxNode) -> Option<Self::Output>;
-    fn visit<N, F>(self, f: F) -> Vis<Self, N, F>
-    where
-        N: AstNode + 'a,
-        F: FnOnce(N) -> Self::Output,
-    {
-        Vis { inner: self, f, ph: PhantomData }
-    }
-}
-
-pub trait VisitorCtx<'a>: Sized {
-    type Output;
-    type Ctx;
-    fn accept(self, node: &'a SyntaxNode) -> Result<Self::Output, Self::Ctx>;
-    fn visit<N, F>(self, f: F) -> VisCtx<Self, N, F>
-    where
-        N: AstNode + 'a,
-        F: FnOnce(N, Self::Ctx) -> Self::Output,
-    {
-        VisCtx { inner: self, f, ph: PhantomData }
-    }
-}
-
-#[derive(Debug)]
-struct EmptyVisitor<T> {
-    ph: PhantomData<fn() -> T>,
-}
-
-impl<'a, T> Visitor<'a> for EmptyVisitor<T> {
-    type Output = T;
-
-    fn accept(self, _node: &'a SyntaxNode) -> Option<T> {
-        None
-    }
-}
-
-#[derive(Debug)]
-struct EmptyVisitorCtx<T, C> {
-    ctx: C,
-    ph: PhantomData<fn() -> T>,
-}
-
-impl<'a, T, C> VisitorCtx<'a> for EmptyVisitorCtx<T, C> {
-    type Output = T;
-    type Ctx = C;
-
-    fn accept(self, _node: &'a SyntaxNode) -> Result<T, C> {
-        Err(self.ctx)
-    }
-}
-
-#[derive(Debug)]
-pub struct Vis<V, N, F> {
-    inner: V,
-    f: F,
-    ph: PhantomData<fn(N)>,
-}
-
-impl<'a, V, N, F> Visitor<'a> for Vis<V, N, F>
-where
-    V: Visitor<'a>,
-    N: AstNode + 'a,
-    F: FnOnce(N) -> <V as Visitor<'a>>::Output,
-{
-    type Output = <V as Visitor<'a>>::Output;
-
-    fn accept(self, node: &'a SyntaxNode) -> Option<Self::Output> {
-        let Vis { inner, f, .. } = self;
-        inner.accept(node).or_else(|| N::cast(node.clone()).map(f))
-    }
-}
-
-#[derive(Debug)]
-pub struct VisCtx<V, N, F> {
-    inner: V,
-    f: F,
-    ph: PhantomData<fn(N)>,
-}
-
-impl<'a, V, N, F> VisitorCtx<'a> for VisCtx<V, N, F>
-where
-    V: VisitorCtx<'a>,
-    N: AstNode + 'a,
-    F: FnOnce(N, <V as VisitorCtx<'a>>::Ctx) -> <V as VisitorCtx<'a>>::Output,
-{
-    type Output = <V as VisitorCtx<'a>>::Output;
-    type Ctx = <V as VisitorCtx<'a>>::Ctx;
-
-    fn accept(self, node: &'a SyntaxNode) -> Result<Self::Output, Self::Ctx> {
-        let VisCtx { inner, f, .. } = self;
-        inner.accept(node).or_else(|ctx| match N::cast(node.clone()) {
-            None => Err(ctx),
-            Some(node) => Ok(f(node, ctx)),
-        })
-    }
-}
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index 3bb5571ee..34b22c3e2 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -1962,6 +1962,7 @@ impl AstNode for ModuleItem {
         }
     }
 }
+impl ast::AttrsOwner for ModuleItem {}
 impl ModuleItem {}
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Name {
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index 30328f59f..25e6f64ce 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -1,5 +1,5 @@
 // Stores definitions which must be used in multiple places
-// See `cargo gen-syntax` (defined in crates/tools/src/main.rs)
+// See `cargo gen-syntax` (defined in crates/ra_tools/src/main.rs)
 Grammar(
     punct: [
         (";", "SEMI"),
@@ -397,7 +397,8 @@ Grammar(
         ),
         "ModuleItem": (
             enum: ["StructDef", "EnumDef", "FnDef", "TraitDef", "TypeAliasDef", "ImplBlock",
-                   "UseItem", "ExternCrateItem", "ConstDef", "StaticDef", "Module" ]
+                   "UseItem", "ExternCrateItem", "ConstDef", "StaticDef", "Module" ],
+            traits: ["AttrsOwner"]
         ),
         "ImplItem": (
             enum: ["FnDef", "TypeAliasDef", "ConstDef"]
diff --git a/crates/ra_syntax/src/lib.rs b/crates/ra_syntax/src/lib.rs
index edb6076bb..c315ba552 100644
--- a/crates/ra_syntax/src/lib.rs
+++ b/crates/ra_syntax/src/lib.rs
@@ -160,6 +160,17 @@ impl SourceFile {
     }
 }
 
+#[macro_export]
+macro_rules! match_ast {
+    (match $node:ident {
+        $( ast::$ast:ident($it:ident) => $res:block, )*
+        _ => $catch_all:expr,
+    }) => {{
+        $( if let Some($it) = ast::$ast::cast($node.clone()) $res else )*
+        { $catch_all }
+    }};
+}
+
 /// This test does not assert anything and instead just shows off the crate's
 /// API.
 #[test]
@@ -294,7 +305,7 @@ fn api_walkthrough() {
     // To recursively process the tree, there are three approaches:
     // 1. explicitly call getter methods on AST nodes.
     // 2. use descendants and `AstNode::cast`.
-    // 3. use descendants and the visitor.
+    // 3. use descendants and `match_ast!`.
     //
     // Here's how the first one looks like:
     let exprs_cast: Vec<String> = file
@@ -304,17 +315,17 @@ fn api_walkthrough() {
         .map(|expr| expr.syntax().text().to_string())
         .collect();
 
-    // An alternative is to use a visitor. The visitor does not do traversal
-    // automatically (so it's more akin to a generic lambda) and is constructed
-    // from closures. This seems more flexible than a single generated visitor
-    // trait.
-    use algo::visit::{visitor, Visitor};
+    // An alternative is to use a macro.
     let mut exprs_visit = Vec::new();
     for node in file.syntax().descendants() {
-        if let Some(result) =
-            visitor().visit::<ast::Expr, _>(|expr| expr.syntax().text().to_string()).accept(&node)
-        {
-            exprs_visit.push(result);
+        match_ast! {
+            match node {
+                ast::Expr(it) => {
+                    let res = it.syntax().text().to_string();
+                    exprs_visit.push(res);
+                },
+                _ => (),
+            }
         }
     }
     assert_eq!(exprs_cast, exprs_visit);
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index 4f8935b2c..ab4f15908 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -5,8 +5,7 @@ mod block;
 use rustc_lexer::unescape;
 
 use crate::{
-    algo::visit::{visitor_ctx, VisitorCtx},
-    ast, AstNode, SyntaxError, SyntaxErrorKind,
+    ast, match_ast, AstNode, SyntaxError, SyntaxErrorKind,
     SyntaxKind::{BYTE, BYTE_STRING, CHAR, INT_NUMBER, STRING},
     SyntaxNode, SyntaxToken, TextUnit, T,
 };
@@ -97,12 +96,15 @@ impl From<rustc_lexer::unescape::EscapeError> for SyntaxErrorKind {
 pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
     let mut errors = Vec::new();
     for node in root.descendants() {
-        let _ = visitor_ctx(&mut errors)
-            .visit::<ast::Literal, _>(validate_literal)
-            .visit::<ast::BlockExpr, _>(block::validate_block_expr)
-            .visit::<ast::FieldExpr, _>(|it, errors| validate_numeric_name(it.name_ref(), errors))
-            .visit::<ast::RecordField, _>(|it, errors| validate_numeric_name(it.name_ref(), errors))
-            .accept(&node);
+        match_ast! {
+            match node {
+                ast::Literal(it) => { validate_literal(it, &mut errors) },
+                ast::BlockExpr(it) => { block::validate_block_expr(it, &mut errors) },
+                ast::FieldExpr(it) => { validate_numeric_name(it.name_ref(), &mut errors) },
+                ast::RecordField(it) => { validate_numeric_name(it.name_ref(), &mut errors) },
+                _ => (),
+            }
+        }
     }
     errors
 }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.rs b/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.rs
index 293046a04..2f8188160 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.rs
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.rs
@@ -1,4 +1,5 @@
 fn foo() {
     while true {};
     while let Some(x) = it.next() {};
+    while { true } {};
 }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.txt b/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.txt
index 9b43d624c..a6e14a114 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.txt
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0031_while_expr.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 70)
-  FN_DEF@[0; 69)
+SOURCE_FILE@[0; 93)
+  FN_DEF@[0; 92)
     FN_KW@[0; 2) "fn"
     WHITESPACE@[2; 3) " "
     NAME@[3; 6)
@@ -8,8 +8,8 @@ SOURCE_FILE@[0; 70)
       L_PAREN@[6; 7) "("
       R_PAREN@[7; 8) ")"
     WHITESPACE@[8; 9) " "
-    BLOCK_EXPR@[9; 69)
-      BLOCK@[9; 69)
+    BLOCK_EXPR@[9; 92)
+      BLOCK@[9; 92)
         L_CURLY@[9; 10) "{"
         WHITESPACE@[10; 15) "\n    "
         EXPR_STMT@[15; 29)
@@ -64,6 +64,26 @@ SOURCE_FILE@[0; 70)
                 L_CURLY@[64; 65) "{"
                 R_CURLY@[65; 66) "}"
           SEMI@[66; 67) ";"
-        WHITESPACE@[67; 68) "\n"
-        R_CURLY@[68; 69) "}"
-  WHITESPACE@[69; 70) "\n"
+        WHITESPACE@[67; 72) "\n    "
+        EXPR_STMT@[72; 90)
+          WHILE_EXPR@[72; 89)
+            WHILE_KW@[72; 77) "while"
+            WHITESPACE@[77; 78) " "
+            CONDITION@[78; 86)
+              BLOCK_EXPR@[78; 86)
+                BLOCK@[78; 86)
+                  L_CURLY@[78; 79) "{"
+                  WHITESPACE@[79; 80) " "
+                  LITERAL@[80; 84)
+                    TRUE_KW@[80; 84) "true"
+                  WHITESPACE@[84; 85) " "
+                  R_CURLY@[85; 86) "}"
+            WHITESPACE@[86; 87) " "
+            BLOCK_EXPR@[87; 89)
+              BLOCK@[87; 89)
+                L_CURLY@[87; 88) "{"
+                R_CURLY@[88; 89) "}"
+          SEMI@[89; 90) ";"
+        WHITESPACE@[90; 91) "\n"
+        R_CURLY@[91; 92) "}"
+  WHITESPACE@[92; 93) "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.rs b/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.rs
index 4b0d9af89..40f227ba3 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.rs
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.rs
@@ -3,4 +3,5 @@ fn foo() {
     if true {} else {};
     if true {} else if false {} else {};
     if S {};
+    if { true } { } else { };
 }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.txt b/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.txt
index 14ea91fd2..2ace3c8ee 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.txt
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0064_if_expr.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 107)
-  FN_DEF@[0; 106)
+SOURCE_FILE@[0; 137)
+  FN_DEF@[0; 136)
     FN_KW@[0; 2) "fn"
     WHITESPACE@[2; 3) " "
     NAME@[3; 6)
@@ -8,8 +8,8 @@ SOURCE_FILE@[0; 107)
       L_PAREN@[6; 7) "("
       R_PAREN@[7; 8) ")"
     WHITESPACE@[8; 9) " "
-    BLOCK_EXPR@[9; 106)
-      BLOCK@[9; 106)
+    BLOCK_EXPR@[9; 136)
+      BLOCK@[9; 136)
         L_CURLY@[9; 10) "{"
         WHITESPACE@[10; 15) "\n    "
         EXPR_STMT@[15; 26)
@@ -98,6 +98,35 @@ SOURCE_FILE@[0; 107)
                 L_CURLY@[101; 102) "{"
                 R_CURLY@[102; 103) "}"
           SEMI@[103; 104) ";"
-        WHITESPACE@[104; 105) "\n"
-        R_CURLY@[105; 106) "}"
-  WHITESPACE@[106; 107) "\n"
+        WHITESPACE@[104; 109) "\n    "
+        EXPR_STMT@[109; 134)
+          IF_EXPR@[109; 133)
+            IF_KW@[109; 111) "if"
+            WHITESPACE@[111; 112) " "
+            CONDITION@[112; 120)
+              BLOCK_EXPR@[112; 120)
+                BLOCK@[112; 120)
+                  L_CURLY@[112; 113) "{"
+                  WHITESPACE@[113; 114) " "
+                  LITERAL@[114; 118)
+                    TRUE_KW@[114; 118) "true"
+                  WHITESPACE@[118; 119) " "
+                  R_CURLY@[119; 120) "}"
+            WHITESPACE@[120; 121) " "
+            BLOCK_EXPR@[121; 124)
+              BLOCK@[121; 124)
+                L_CURLY@[121; 122) "{"
+                WHITESPACE@[122; 123) " "
+                R_CURLY@[123; 124) "}"
+            WHITESPACE@[124; 125) " "
+            ELSE_KW@[125; 129) "else"
+            WHITESPACE@[129; 130) " "
+            BLOCK_EXPR@[130; 133)
+              BLOCK@[130; 133)
+                L_CURLY@[130; 131) "{"
+                WHITESPACE@[131; 132) " "
+                R_CURLY@[132; 133) "}"
+          SEMI@[133; 134) ";"
+        WHITESPACE@[134; 135) "\n"
+        R_CURLY@[135; 136) "}"
+  WHITESPACE@[136; 137) "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.rs b/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.rs
index c9205dfa3..c4021dc10 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.rs
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.rs
@@ -1,4 +1,6 @@
 fn foo() {
     match () { };
     match S {};
+    match { } { _ => () };
+    match { S {} } {};
 }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.txt b/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.txt
index f62b6c6d5..0af668056 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.txt
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0071_match_expr.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 47)
-  FN_DEF@[0; 46)
+SOURCE_FILE@[0; 97)
+  FN_DEF@[0; 96)
     FN_KW@[0; 2) "fn"
     WHITESPACE@[2; 3) " "
     NAME@[3; 6)
@@ -8,8 +8,8 @@ SOURCE_FILE@[0; 47)
       L_PAREN@[6; 7) "("
       R_PAREN@[7; 8) ")"
     WHITESPACE@[8; 9) " "
-    BLOCK_EXPR@[9; 46)
-      BLOCK@[9; 46)
+    BLOCK_EXPR@[9; 96)
+      BLOCK@[9; 96)
         L_CURLY@[9; 10) "{"
         WHITESPACE@[10; 15) "\n    "
         EXPR_STMT@[15; 28)
@@ -40,6 +40,57 @@ SOURCE_FILE@[0; 47)
               L_CURLY@[41; 42) "{"
               R_CURLY@[42; 43) "}"
           SEMI@[43; 44) ";"
-        WHITESPACE@[44; 45) "\n"
-        R_CURLY@[45; 46) "}"
-  WHITESPACE@[46; 47) "\n"
+        WHITESPACE@[44; 49) "\n    "
+        EXPR_STMT@[49; 71)
+          MATCH_EXPR@[49; 70)
+            MATCH_KW@[49; 54) "match"
+            WHITESPACE@[54; 55) " "
+            BLOCK_EXPR@[55; 58)
+              BLOCK@[55; 58)
+                L_CURLY@[55; 56) "{"
+                WHITESPACE@[56; 57) " "
+                R_CURLY@[57; 58) "}"
+            WHITESPACE@[58; 59) " "
+            MATCH_ARM_LIST@[59; 70)
+              L_CURLY@[59; 60) "{"
+              WHITESPACE@[60; 61) " "
+              MATCH_ARM@[61; 68)
+                PLACEHOLDER_PAT@[61; 62)
+                  UNDERSCORE@[61; 62) "_"
+                WHITESPACE@[62; 63) " "
+                FAT_ARROW@[63; 65) "=>"
+                WHITESPACE@[65; 66) " "
+                TUPLE_EXPR@[66; 68)
+                  L_PAREN@[66; 67) "("
+                  R_PAREN@[67; 68) ")"
+              WHITESPACE@[68; 69) " "
+              R_CURLY@[69; 70) "}"
+          SEMI@[70; 71) ";"
+        WHITESPACE@[71; 76) "\n    "
+        EXPR_STMT@[76; 94)
+          MATCH_EXPR@[76; 93)
+            MATCH_KW@[76; 81) "match"
+            WHITESPACE@[81; 82) " "
+            BLOCK_EXPR@[82; 90)
+              BLOCK@[82; 90)
+                L_CURLY@[82; 83) "{"
+                WHITESPACE@[83; 84) " "
+                RECORD_LIT@[84; 88)
+                  PATH@[84; 85)
+                    PATH_SEGMENT@[84; 85)
+                      NAME_REF@[84; 85)
+                        IDENT@[84; 85) "S"
+                  WHITESPACE@[85; 86) " "
+                  RECORD_FIELD_LIST@[86; 88)
+                    L_CURLY@[86; 87) "{"
+                    R_CURLY@[87; 88) "}"
+                WHITESPACE@[88; 89) " "
+                R_CURLY@[89; 90) "}"
+            WHITESPACE@[90; 91) " "
+            MATCH_ARM_LIST@[91; 93)
+              L_CURLY@[91; 92) "{"
+              R_CURLY@[92; 93) "}"
+          SEMI@[93; 94) ";"
+        WHITESPACE@[94; 95) "\n"
+        R_CURLY@[95; 96) "}"
+  WHITESPACE@[96; 97) "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.rs b/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.rs
index c39fe8e68..e7b7cfc6b 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.rs
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.rs
@@ -1 +1,5 @@
-fn foo() { let x = 1..; }
+fn foo() {
+    let x = 1..;
+    match 1.. { _ => () };
+    match a.b()..S { _ => () };
+}
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.txt b/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.txt
index f3c292f5e..9f8a6b0f6 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.txt
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0080_postfix_range.txt
@@ -1,5 +1,5 @@
-SOURCE_FILE@[0; 26)
-  FN_DEF@[0; 25)
+SOURCE_FILE@[0; 89)
+  FN_DEF@[0; 88)
     FN_KW@[0; 2) "fn"
     WHITESPACE@[2; 3) " "
     NAME@[3; 6)
@@ -8,24 +8,89 @@ SOURCE_FILE@[0; 26)
       L_PAREN@[6; 7) "("
       R_PAREN@[7; 8) ")"
     WHITESPACE@[8; 9) " "
-    BLOCK_EXPR@[9; 25)
-      BLOCK@[9; 25)
+    BLOCK_EXPR@[9; 88)
+      BLOCK@[9; 88)
         L_CURLY@[9; 10) "{"
-        WHITESPACE@[10; 11) " "
-        LET_STMT@[11; 23)
-          LET_KW@[11; 14) "let"
-          WHITESPACE@[14; 15) " "
-          BIND_PAT@[15; 16)
-            NAME@[15; 16)
-              IDENT@[15; 16) "x"
-          WHITESPACE@[16; 17) " "
-          EQ@[17; 18) "="
+        WHITESPACE@[10; 15) "\n    "
+        LET_STMT@[15; 27)
+          LET_KW@[15; 18) "let"
           WHITESPACE@[18; 19) " "
-          RANGE_EXPR@[19; 22)
-            LITERAL@[19; 20)
-              INT_NUMBER@[19; 20) "1"
-            DOTDOT@[20; 22) ".."
-          SEMI@[22; 23) ";"
-        WHITESPACE@[23; 24) " "
-        R_CURLY@[24; 25) "}"
-  WHITESPACE@[25; 26) "\n"
+          BIND_PAT@[19; 20)
+            NAME@[19; 20)
+              IDENT@[19; 20) "x"
+          WHITESPACE@[20; 21) " "
+          EQ@[21; 22) "="
+          WHITESPACE@[22; 23) " "
+          RANGE_EXPR@[23; 26)
+            LITERAL@[23; 24)
+              INT_NUMBER@[23; 24) "1"
+            DOTDOT@[24; 26) ".."
+          SEMI@[26; 27) ";"
+        WHITESPACE@[27; 32) "\n    "
+        EXPR_STMT@[32; 54)
+          MATCH_EXPR@[32; 53)
+            MATCH_KW@[32; 37) "match"
+            WHITESPACE@[37; 38) " "
+            RANGE_EXPR@[38; 41)
+              LITERAL@[38; 39)
+                INT_NUMBER@[38; 39) "1"
+              DOTDOT@[39; 41) ".."
+            WHITESPACE@[41; 42) " "
+            MATCH_ARM_LIST@[42; 53)
+              L_CURLY@[42; 43) "{"
+              WHITESPACE@[43; 44) " "
+              MATCH_ARM@[44; 51)
+                PLACEHOLDER_PAT@[44; 45)
+                  UNDERSCORE@[44; 45) "_"
+                WHITESPACE@[45; 46) " "
+                FAT_ARROW@[46; 48) "=>"
+                WHITESPACE@[48; 49) " "
+                TUPLE_EXPR@[49; 51)
+                  L_PAREN@[49; 50) "("
+                  R_PAREN@[50; 51) ")"
+              WHITESPACE@[51; 52) " "
+              R_CURLY@[52; 53) "}"
+          SEMI@[53; 54) ";"
+        WHITESPACE@[54; 59) "\n    "
+        EXPR_STMT@[59; 86)
+          MATCH_EXPR@[59; 85)
+            MATCH_KW@[59; 64) "match"
+            WHITESPACE@[64; 65) " "
+            RANGE_EXPR@[65; 73)
+              METHOD_CALL_EXPR@[65; 70)
+                PATH_EXPR@[65; 66)
+                  PATH@[65; 66)
+                    PATH_SEGMENT@[65; 66)
+                      NAME_REF@[65; 66)
+                        IDENT@[65; 66) "a"
+                DOT@[66; 67) "."
+                NAME_REF@[67; 68)
+                  IDENT@[67; 68) "b"
+                ARG_LIST@[68; 70)
+                  L_PAREN@[68; 69) "("
+                  R_PAREN@[69; 70) ")"
+              DOTDOT@[70; 72) ".."
+              PATH_EXPR@[72; 73)
+                PATH@[72; 73)
+                  PATH_SEGMENT@[72; 73)
+                    NAME_REF@[72; 73)
+                      IDENT@[72; 73) "S"
+            WHITESPACE@[73; 74) " "
+            MATCH_ARM_LIST@[74; 85)
+              L_CURLY@[74; 75) "{"
+              WHITESPACE@[75; 76) " "
+              MATCH_ARM@[76; 83)
+                PLACEHOLDER_PAT@[76; 77)
+                  UNDERSCORE@[76; 77) "_"
+                WHITESPACE@[77; 78) " "
+                FAT_ARROW@[78; 80) "=>"
+                WHITESPACE@[80; 81) " "
+                TUPLE_EXPR@[81; 83)
+                  L_PAREN@[81; 82) "("
+                  R_PAREN@[82; 83) ")"
+              WHITESPACE@[83; 84) " "
+              R_CURLY@[84; 85) "}"
+          SEMI@[85; 86) ";"
+        WHITESPACE@[86; 87) "\n"
+        R_CURLY@[87; 88) "}"
+  WHITESPACE@[88; 89) "\n"