16 files changed, 1424 insertions, 803 deletions

diff --git a/crates/assists/src/handlers/generate_function.rs b/crates/assists/src/handlers/generate_function.rs
index b38d64058..d23f4293b 100644
--- a/crates/assists/src/handlers/generate_function.rs
+++ b/crates/assists/src/handlers/generate_function.rs
@@ -36,8 +36,8 @@ use crate::{
 //     bar("", baz());
 // }
 //
-// fn bar(arg: &str, baz: Baz) {
-//     ${0:todo!()}
+// fn bar(arg: &str, baz: Baz) ${0:-> ()} {
+//     todo!()
 // }
 //
 // ```
@@ -80,9 +80,9 @@ pub(crate) fn generate_function(acc: &mut Assists, ctx: &AssistContext) -> Optio
 
 struct FunctionTemplate {
     insert_offset: TextSize,
-    placeholder_expr: ast::MacroCall,
     leading_ws: String,
     fn_def: ast::Fn,
+    ret_type: ast::RetType,
     trailing_ws: String,
     file: FileId,
 }
@@ -90,11 +90,9 @@ struct FunctionTemplate {
 impl FunctionTemplate {
     fn to_string(&self, cap: Option<SnippetCap>) -> String {
         let f = match cap {
-            Some(cap) => render_snippet(
-                cap,
-                self.fn_def.syntax(),
-                Cursor::Replace(self.placeholder_expr.syntax()),
-            ),
+            Some(cap) => {
+                render_snippet(cap, self.fn_def.syntax(), Cursor::Replace(self.ret_type.syntax()))
+            }
             None => self.fn_def.to_string(),
         };
         format!("{}{}{}", self.leading_ws, f, self.trailing_ws)
@@ -141,8 +139,14 @@ impl FunctionBuilder {
         let placeholder_expr = make::expr_todo();
         let fn_body = make::block_expr(vec![], Some(placeholder_expr));
         let visibility = if self.needs_pub { Some(make::visibility_pub_crate()) } else { None };
-        let mut fn_def =
-            make::fn_(visibility, self.fn_name, self.type_params, self.params, fn_body);
+        let mut fn_def = make::fn_(
+            visibility,
+            self.fn_name,
+            self.type_params,
+            self.params,
+            fn_body,
+            Some(make::ret_type(make::ty("()"))),
+        );
         let leading_ws;
         let trailing_ws;
 
@@ -163,12 +167,10 @@ impl FunctionBuilder {
             }
         };
 
-        let placeholder_expr =
-            fn_def.syntax().descendants().find_map(ast::MacroCall::cast).unwrap();
         FunctionTemplate {
             insert_offset,
-            placeholder_expr,
             leading_ws,
+            ret_type: fn_def.ret_type().unwrap(),
             fn_def,
             trailing_ws,
             file: self.file,
@@ -349,8 +351,8 @@ fn foo() {
     bar();
 }
 
-fn bar() {
-    ${0:todo!()}
+fn bar() ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -376,8 +378,8 @@ impl Foo {
     }
 }
 
-fn bar() {
-    ${0:todo!()}
+fn bar() ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -400,8 +402,8 @@ fn foo1() {
     bar();
 }
 
-fn bar() {
-    ${0:todo!()}
+fn bar() ${0:-> ()} {
+    todo!()
 }
 
 fn foo2() {}
@@ -426,8 +428,8 @@ mod baz {
         bar();
     }
 
-    fn bar() {
-        ${0:todo!()}
+    fn bar() ${0:-> ()} {
+        todo!()
     }
 }
 ",
@@ -452,8 +454,8 @@ fn foo() {
     bar(baz());
 }
 
-fn bar(baz: Baz) {
-    ${0:todo!()}
+fn bar(baz: Baz) ${0:-> ()} {
+    todo!()
 }
 ",
         );
@@ -485,8 +487,8 @@ impl Baz {
     }
 }
 
-fn bar(baz: Baz) {
-    ${0:todo!()}
+fn bar(baz: Baz) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -506,8 +508,8 @@ fn foo() {
     bar("bar")
 }
 
-fn bar(arg: &str) {
-    ${0:todo!()}
+fn bar(arg: &str) ${0:-> ()} {
+    todo!()
 }
 "#,
         )
@@ -527,8 +529,8 @@ fn foo() {
     bar('x')
 }
 
-fn bar(arg: char) {
-    ${0:todo!()}
+fn bar(arg: char) ${0:-> ()} {
+    todo!()
 }
 "#,
         )
@@ -548,8 +550,8 @@ fn foo() {
     bar(42)
 }
 
-fn bar(arg: i32) {
-    ${0:todo!()}
+fn bar(arg: i32) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -569,8 +571,8 @@ fn foo() {
     bar(42 as u8)
 }
 
-fn bar(arg: u8) {
-    ${0:todo!()}
+fn bar(arg: u8) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -594,8 +596,8 @@ fn foo() {
     bar(x as u8)
 }
 
-fn bar(x: u8) {
-    ${0:todo!()}
+fn bar(x: u8) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -617,8 +619,8 @@ fn foo() {
     bar(worble)
 }
 
-fn bar(worble: ()) {
-    ${0:todo!()}
+fn bar(worble: ()) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -646,8 +648,8 @@ fn baz() {
     bar(foo())
 }
 
-fn bar(foo: impl Foo) {
-    ${0:todo!()}
+fn bar(foo: impl Foo) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -673,8 +675,8 @@ fn foo() {
     bar(&baz())
 }
 
-fn bar(baz: &Baz) {
-    ${0:todo!()}
+fn bar(baz: &Baz) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -702,8 +704,8 @@ fn foo() {
     bar(Baz::baz())
 }
 
-fn bar(baz: Baz::Bof) {
-    ${0:todo!()}
+fn bar(baz: Baz::Bof) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -725,8 +727,8 @@ fn foo<T>(t: T) {
     bar(t)
 }
 
-fn bar<T>(t: T) {
-    ${0:todo!()}
+fn bar<T>(t: T) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -756,8 +758,8 @@ fn foo() {
     bar(Baz::new);
 }
 
-fn bar(arg: fn() -> Baz) {
-    ${0:todo!()}
+fn bar(arg: fn() -> Baz) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -781,8 +783,8 @@ fn foo() {
     bar(closure)
 }
 
-fn bar(closure: impl Fn(i64) -> i64) {
-    ${0:todo!()}
+fn bar(closure: impl Fn(i64) -> i64) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -802,8 +804,8 @@ fn foo() {
     bar(baz)
 }
 
-fn bar(baz: ()) {
-    ${0:todo!()}
+fn bar(baz: ()) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -827,8 +829,8 @@ fn foo() {
     bar(baz(), baz())
 }
 
-fn bar(baz_1: Baz, baz_2: Baz) {
-    ${0:todo!()}
+fn bar(baz_1: Baz, baz_2: Baz) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -852,8 +854,8 @@ fn foo() {
     bar(baz(), baz(), "foo", "bar")
 }
 
-fn bar(baz_1: Baz, baz_2: Baz, arg_1: &str, arg_2: &str) {
-    ${0:todo!()}
+fn bar(baz_1: Baz, baz_2: Baz, arg_1: &str, arg_2: &str) ${0:-> ()} {
+    todo!()
 }
 "#,
         )
@@ -872,8 +874,8 @@ fn foo() {
 ",
             r"
 mod bar {
-    pub(crate) fn my_fn() {
-        ${0:todo!()}
+    pub(crate) fn my_fn() ${0:-> ()} {
+        todo!()
     }
 }
 
@@ -911,8 +913,8 @@ fn bar() {
     baz(foo)
 }
 
-fn baz(foo: foo::Foo) {
-    ${0:todo!()}
+fn baz(foo: foo::Foo) ${0:-> ()} {
+    todo!()
 }
 ",
         )
@@ -935,8 +937,8 @@ fn foo() {
 mod bar {
     fn something_else() {}
 
-    pub(crate) fn my_fn() {
-        ${0:todo!()}
+    pub(crate) fn my_fn() ${0:-> ()} {
+        todo!()
     }
 }
 
@@ -963,8 +965,8 @@ fn foo() {
             r"
 mod bar {
     mod baz {
-        pub(crate) fn my_fn() {
-            ${0:todo!()}
+        pub(crate) fn my_fn() ${0:-> ()} {
+            todo!()
         }
     }
 }
@@ -992,8 +994,8 @@ fn main() {
             r"
 
 
-pub(crate) fn bar() {
-    ${0:todo!()}
+pub(crate) fn bar() ${0:-> ()} {
+    todo!()
 }",
         )
     }
diff --git a/crates/assists/src/tests/generated.rs b/crates/assists/src/tests/generated.rs
index 7f6e98a54..41f536574 100644
--- a/crates/assists/src/tests/generated.rs
+++ b/crates/assists/src/tests/generated.rs
@@ -454,8 +454,8 @@ fn foo() {
     bar("", baz());
 }
 
-fn bar(arg: &str, baz: Baz) {
-    ${0:todo!()}
+fn bar(arg: &str, baz: Baz) ${0:-> ()} {
+    todo!()
 }
 
 "#####,
diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
index c330314d4..215ac4b41 100644
--- a/crates/base_db/src/input.rs
+++ b/crates/base_db/src/input.rs
@@ -221,6 +221,34 @@ impl CrateGraph {
         deps.into_iter()
     }
 
+    /// Returns all crates in the graph, sorted in topological order (ie. dependencies of a crate
+    /// come before the crate itself).
+    pub fn crates_in_topological_order(&self) -> Vec<CrateId> {
+        let mut res = Vec::new();
+        let mut visited = FxHashSet::default();
+
+        for krate in self.arena.keys().copied() {
+            go(self, &mut visited, &mut res, krate);
+        }
+
+        return res;
+
+        fn go(
+            graph: &CrateGraph,
+            visited: &mut FxHashSet<CrateId>,
+            res: &mut Vec<CrateId>,
+            source: CrateId,
+        ) {
+            if !visited.insert(source) {
+                return;
+            }
+            for dep in graph[source].dependencies.iter() {
+                go(graph, visited, res, dep.crate_id)
+            }
+            res.push(source)
+        }
+    }
+
     // FIXME: this only finds one crate with the given root; we could have multiple
     pub fn crate_id_for_crate_root(&self, file_id: FileId) -> Option<CrateId> {
         let (&crate_id, _) =
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index fb85041fd..b65be4fe1 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -1411,7 +1411,7 @@ impl Type {
         r#trait: Trait,
         args: &[Type],
         alias: TypeAlias,
-    ) -> Option<Ty> {
+    ) -> Option<Type> {
         let subst = Substs::build_for_def(db, r#trait.id)
             .push(self.ty.value.clone())
             .fill(args.iter().map(|t| t.ty.value.clone()))
@@ -1432,6 +1432,10 @@ impl Type {
             Solution::Unique(SolutionVariables(subst)) => subst.value.first().cloned(),
             Solution::Ambig(_) => None,
         }
+        .map(|ty| Type {
+            krate: self.krate,
+            ty: InEnvironment { value: ty, environment: Arc::clone(&self.ty.environment) },
+        })
     }
 
     pub fn is_copy(&self, db: &dyn HirDatabase) -> bool {
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 2d91bb21f..01e72690a 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -107,7 +107,10 @@ impl ExprCollector<'_> {
                 let param_pat = self.alloc_pat(
                     Pat::Bind {
                         name: name![self],
-                        mode: BindingAnnotation::Unannotated,
+                        mode: BindingAnnotation::new(
+                            self_param.mut_token().is_some() && self_param.amp_token().is_none(),
+                            false,
+                        ),
                         subpat: None,
                     },
                     Either::Right(ptr),
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 7d716577e..e2079bbcf 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -220,8 +220,8 @@ fn hint_iterator(
     }
     let iter_trait = FamousDefs(sema, krate).core_iter_Iterator()?;
     let iter_mod = FamousDefs(sema, krate).core_iter()?;
-    // assert this type comes from `core::iter`
-    iter_mod.visibility_of(db, &iter_trait.into()).filter(|&vis| vis == hir::Visibility::Public)?;
+    // assert this struct comes from `core::iter`
+    iter_mod.visibility_of(db, &strukt.into()).filter(|&vis| vis == hir::Visibility::Public)?;
     if ty.impls_trait(db, iter_trait, &[]) {
         let assoc_type_item = iter_trait.items(db).into_iter().find_map(|item| match item {
             hir::AssocItem::TypeAlias(alias) if alias.name(db) == known::Item => Some(alias),
@@ -231,12 +231,17 @@ fn hint_iterator(
             const LABEL_START: &str = "impl Iterator<Item = ";
             const LABEL_END: &str = ">";
 
-            let ty_display = ty.display_truncated(
-                db,
-                config
-                    .max_length
-                    .map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len())),
-            );
+            let ty_display = hint_iterator(sema, config, &ty)
+                .map(|assoc_type_impl| assoc_type_impl.to_string())
+                .unwrap_or_else(|| {
+                    ty.display_truncated(
+                        db,
+                        config
+                            .max_length
+                            .map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len())),
+                    )
+                    .to_string()
+                });
             return Some(format!("{}{}{}", LABEL_START, ty_display, LABEL_END).into());
         }
     }
@@ -1002,18 +1007,6 @@ fn main() {
 
     println!("Unit expr");
 }
-
-//- /alloc.rs crate:alloc deps:core
-mod collections {
-    struct Vec<T> {}
-    impl<T> Vec<T> {
-        fn new() -> Self { Vec {} }
-        fn push(&mut self, t: T) { }
-    }
-    impl<T> IntoIterator for Vec<T> {
-        type Item=T;
-    }
-}
 "#,
         );
     }
@@ -1043,17 +1036,6 @@ fn main() {
         //^ &str
     }
 }
-//- /alloc.rs crate:alloc deps:core
-mod collections {
-    struct Vec<T> {}
-    impl<T> Vec<T> {
-        fn new() -> Self { Vec {} }
-        fn push(&mut self, t: T) { }
-    }
-    impl<T> IntoIterator for Vec<T> {
-        type Item=T;
-    }
-}
 "#,
         );
     }
@@ -1183,4 +1165,41 @@ fn main() {
             "#]],
         );
     }
+
+    #[test]
+    fn shorten_iterators_in_associated_params() {
+        check_with_config(
+            InlayHintsConfig {
+                parameter_hints: false,
+                type_hints: true,
+                chaining_hints: false,
+                max_length: None,
+            },
+            r#"
+use core::iter;
+
+pub struct SomeIter<T> {}
+
+impl<T> SomeIter<T> {
+    pub fn new() -> Self { SomeIter {} }
+    pub fn push(&mut self, t: T) {}
+}
+
+impl<T> Iterator for SomeIter<T> {
+    type Item = T;
+    fn next(&mut self) -> Option<Self::Item> {
+        None
+    }
+}
+
+fn main() {
+    let mut some_iter = SomeIter::new();
+      //^^^^^^^^^^^^^ SomeIter<Take<Repeat<i32>>>
+      some_iter.push(iter::repeat(2).take(2));
+    let iter_of_iters = some_iter.take(2);
+      //^^^^^^^^^^^^^ impl Iterator<Item = impl Iterator<Item = i32>>
+}
+"#,
+        );
+    }
 }
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 686cee3a1..aaf9b3b4b 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -77,6 +77,7 @@ pub use crate::{
     hover::{HoverAction, HoverConfig, HoverGotoTypeData, HoverResult},
     inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
     markup::Markup,
+    prime_caches::PrimeCachesProgress,
     references::{
         Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult, RenameError,
     },
@@ -223,8 +224,11 @@ impl Analysis {
         self.with_db(|db| status::status(&*db, file_id))
     }
 
-    pub fn prime_caches(&self, files: Vec<FileId>) -> Cancelable<()> {
-        self.with_db(|db| prime_caches::prime_caches(db, files))
+    pub fn prime_caches<F>(&self, cb: F) -> Cancelable<()>
+    where
+        F: Fn(PrimeCachesProgress) + Sync + std::panic::UnwindSafe,
+    {
+        self.with_db(move |db| prime_caches::prime_caches(db, &cb))
     }
 
     /// Gets the text of the source file.
diff --git a/crates/ide/src/prime_caches.rs b/crates/ide/src/prime_caches.rs
index c5ab5a1d8..9687c2734 100644
--- a/crates/ide/src/prime_caches.rs
+++ b/crates/ide/src/prime_caches.rs
@@ -3,10 +3,45 @@
 //! request takes longer to compute. This modules implemented prepopulating of
 //! various caches, it's not really advanced at the moment.
 
-use crate::{FileId, RootDatabase};
+use base_db::SourceDatabase;
+use hir::db::DefDatabase;
 
-pub(crate) fn prime_caches(db: &RootDatabase, files: Vec<FileId>) {
-    for file in files {
-        let _ = crate::syntax_highlighting::highlight(db, file, None, false);
+use crate::RootDatabase;
+
+#[derive(Debug)]
+pub enum PrimeCachesProgress {
+    Started,
+    /// We started indexing a crate.
+    StartedOnCrate {
+        on_crate: String,
+        n_done: usize,
+        n_total: usize,
+    },
+    /// We finished indexing all crates.
+    Finished,
+}
+
+pub(crate) fn prime_caches(db: &RootDatabase, cb: &(dyn Fn(PrimeCachesProgress) + Sync)) {
+    let _p = profile::span("prime_caches");
+    let graph = db.crate_graph();
+    let topo = &graph.crates_in_topological_order();
+
+    cb(PrimeCachesProgress::Started);
+
+    // FIXME: This would be easy to parallelize, since it's in the ideal ordering for that.
+    // Unfortunately rayon prevents panics from propagation out of a `scope`, which breaks
+    // cancellation, so we cannot use rayon.
+    for (i, krate) in topo.iter().enumerate() {
+        let crate_name =
+            graph[*krate].declaration_name.as_ref().map(ToString::to_string).unwrap_or_default();
+
+        cb(PrimeCachesProgress::StartedOnCrate {
+            on_crate: crate_name,
+            n_done: i,
+            n_total: topo.len(),
+        });
+        db.crate_def_map(*krate);
     }
+
+    cb(PrimeCachesProgress::Finished);
 }
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index d9fc25d88..6aafd6fd5 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -68,7 +68,7 @@ pub(crate) fn highlight(
     // When we leave a node, the we use it to flatten the highlighted ranges.
     let mut stack = HighlightedRangeStack::new();
 
-    let mut current_macro_call: Option<ast::MacroCall> = None;
+    let mut current_macro_call: Option<(ast::MacroCall, Option<MacroMatcherParseState>)> = None;
     let mut format_string: Option<SyntaxElement> = None;
 
     // Walk all nodes, keeping track of whether we are inside a macro or not.
@@ -92,7 +92,6 @@ pub(crate) fn highlight(
         // Track "inside macro" state
         match event.clone().map(|it| it.into_node().and_then(ast::MacroCall::cast)) {
             WalkEvent::Enter(Some(mc)) => {
-                current_macro_call = Some(mc.clone());
                 if let Some(range) = macro_call_range(&mc) {
                     stack.add(HighlightedRange {
                         range,
@@ -100,7 +99,9 @@ pub(crate) fn highlight(
                         binding_hash: None,
                     });
                 }
+                let mut is_macro_rules = None;
                 if let Some(name) = mc.is_macro_rules() {
+                    is_macro_rules = Some(MacroMatcherParseState::new());
                     if let Some((highlight, binding_hash)) = highlight_element(
                         &sema,
                         &mut bindings_shadow_count,
@@ -114,10 +115,11 @@ pub(crate) fn highlight(
                         });
                     }
                 }
+                current_macro_call = Some((mc.clone(), is_macro_rules));
                 continue;
             }
             WalkEvent::Leave(Some(mc)) => {
-                assert!(current_macro_call == Some(mc));
+                assert!(current_macro_call.map(|it| it.0) == Some(mc));
                 current_macro_call = None;
                 format_string = None;
             }
@@ -146,6 +148,20 @@ pub(crate) fn highlight(
             WalkEvent::Leave(_) => continue,
         };
 
+        // check if in matcher part of a macro_rules rule
+        if let Some((_, Some(ref mut state))) = current_macro_call {
+            if let Some(tok) = element.as_token() {
+                if matches!(
+                    update_macro_rules_state(tok, state),
+                    RuleState::Matcher | RuleState::Expander
+                ) {
+                    if skip_metavariables(element.clone()) {
+                        continue;
+                    }
+                }
+            }
+        }
+
         let range = element.text_range();
 
         let element_to_highlight = if current_macro_call.is_some() && element.kind() != COMMENT {
@@ -918,3 +934,99 @@ fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabas
         _ => default.into(),
     }
 }
+
+struct MacroMatcherParseState {
+    /// Opening and corresponding closing bracket of the matcher or expander of the current rule
+    paren_ty: Option<(SyntaxKind, SyntaxKind)>,
+    paren_level: usize,
+    rule_state: RuleState,
+    /// Whether we are inside the outer `{` `}` macro block that holds the rules
+    in_invoc_body: bool,
+}
+
+impl MacroMatcherParseState {
+    fn new() -> Self {
+        MacroMatcherParseState {
+            paren_ty: None,
+            paren_level: 0,
+            in_invoc_body: false,
+            rule_state: RuleState::None,
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq)]
+enum RuleState {
+    Matcher,
+    Expander,
+    Between,
+    None,
+}
+
+impl RuleState {
+    fn transition(&mut self) {
+        *self = match self {
+            RuleState::Matcher => RuleState::Between,
+            RuleState::Expander => RuleState::None,
+            RuleState::Between => RuleState::Expander,
+            RuleState::None => RuleState::Matcher,
+        };
+    }
+}
+
+fn update_macro_rules_state(tok: &SyntaxToken, state: &mut MacroMatcherParseState) -> RuleState {
+    if !state.in_invoc_body {
+        if tok.kind() == T!['{'] {
+            state.in_invoc_body = true;
+        }
+        return state.rule_state;
+    }
+
+    match state.paren_ty {
+        Some((open, close)) => {
+            if tok.kind() == open {
+                state.paren_level += 1;
+            } else if tok.kind() == close {
+                state.paren_level -= 1;
+                if state.paren_level == 0 {
+                    let res = state.rule_state;
+                    state.rule_state.transition();
+                    state.paren_ty = None;
+                    return res;
+                }
+            }
+        }
+        None => {
+            match tok.kind() {
+                T!['('] => {
+                    state.paren_ty = Some((T!['('], T![')']));
+                }
+                T!['{'] => {
+                    state.paren_ty = Some((T!['{'], T!['}']));
+                }
+                T!['['] => {
+                    state.paren_ty = Some((T!['['], T![']']));
+                }
+                _ => (),
+            }
+            if state.paren_ty.is_some() {
+                state.paren_level = 1;
+                state.rule_state.transition();
+            }
+        }
+    }
+    state.rule_state
+}
+
+fn skip_metavariables(element: SyntaxElement) -> bool {
+    let tok = match element.as_token() {
+        Some(tok) => tok,
+        None => return false,
+    };
+    let is_fragment = || tok.prev_token().map(|tok| tok.kind()) == Some(T![$]);
+    match tok.kind() {
+        IDENT if is_fragment() => true,
+        kind if kind.is_keyword() && is_fragment() => true,
+        _ => false,
+    }
+}
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html b/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
index 1b681b2c6..43f1b32fd 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_strings.html
@@ -37,7 +37,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 </style>
 <pre><code><span class="macro">macro_rules!</span> <span class="macro declaration">println</span> <span class="punctuation">{</span>
     <span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>arg<span class="punctuation">:</span>tt<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">(</span><span class="punctuation">{</span>
-        <span class="punctuation">$</span><span class="keyword">crate</span><span class="punctuation">:</span><span class="punctuation">:</span>io<span class="punctuation">:</span><span class="punctuation">:</span>_print<span class="punctuation">(</span><span class="punctuation">$</span><span class="keyword">crate</span><span class="punctuation">:</span><span class="punctuation">:</span>format_args_nl<span class="punctuation">!</span><span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>arg<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span><span class="punctuation">)</span><span class="punctuation">;</span>
+        <span class="punctuation">$</span>crate<span class="punctuation">:</span><span class="punctuation">:</span>io<span class="punctuation">:</span><span class="punctuation">:</span>_print<span class="punctuation">(</span><span class="punctuation">$</span>crate<span class="punctuation">:</span><span class="punctuation">:</span>format_args_nl<span class="punctuation">!</span><span class="punctuation">(</span><span class="punctuation">$</span><span class="punctuation">(</span><span class="punctuation">$</span>arg<span class="punctuation">)</span><span class="punctuation">*</span><span class="punctuation">)</span><span class="punctuation">)</span><span class="punctuation">;</span>
     <span class="punctuation">}</span><span class="punctuation">)</span>
 <span class="punctuation">}</span>
 #[rustc_builtin_macro]
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index 1d8a3c404..0bb0928e4 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -62,7 +62,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
 <span class="keyword">impl</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
     <span class="keyword">fn</span> <span class="function declaration">baz</span><span class="punctuation">(</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">,</span> <span class="value_param declaration">f</span><span class="punctuation">:</span> <span class="struct">Foo</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="builtin_type">i32</span> <span class="punctuation">{</span>
-        <span class="value_param">f</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="self_keyword consuming">self</span><span class="punctuation">)</span>
+        <span class="value_param">f</span><span class="punctuation">.</span><span class="function consuming">baz</span><span class="punctuation">(</span><span class="self_keyword mutable consuming">self</span><span class="punctuation">)</span>
     <span class="punctuation">}</span>
 
     <span class="keyword">fn</span> <span class="function declaration">qux</span><span class="punctuation">(</span><span class="operator">&</span><span class="keyword">mut</span> <span class="self_keyword mutable">self</span><span class="punctuation">)</span> <span class="punctuation">{</span>
@@ -115,6 +115,10 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="punctuation">}</span>
 <span class="punctuation">}</span>
 
+<span class="macro">macro_rules!</span> <span class="macro declaration">keyword_frag</span> <span class="punctuation">{</span>
+    <span class="punctuation">(</span><span class="punctuation">$</span>type<span class="punctuation">:</span>ty<span class="punctuation">)</span> <span class="operator">=</span><span class="punctuation">&gt;</span> <span class="punctuation">(</span><span class="punctuation">$</span>type<span class="punctuation">)</span>
+<span class="punctuation">}</span>
+
 <span class="comment">// comment</span>
 <span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
     <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"Hello, {}!"</span><span class="punctuation">,</span> <span class="numeric_literal">92</span><span class="punctuation">)</span><span class="punctuation">;</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index 694c4b7fa..126363b8b 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -89,6 +89,10 @@ macro_rules! noop {
     }
 }
 
+macro_rules! keyword_frag {
+    ($type:ty) => ($type)
+}
+
 // comment
 fn main() {
     println!("Hello, {}!", 92);
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 06b38d99c..fb18f9014 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -7,6 +7,7 @@ use std::{
 
 use base_db::VfsPath;
 use crossbeam_channel::{select, Receiver};
+use ide::PrimeCachesProgress;
 use ide::{Canceled, FileId};
 use lsp_server::{Connection, Notification, Request, Response};
 use lsp_types::notification::Notification as _;
@@ -61,7 +62,7 @@ pub(crate) enum Task {
     Response(Response),
     Diagnostics(Vec<(FileId, Vec<lsp_types::Diagnostic>)>),
     Workspaces(Vec<anyhow::Result<ProjectWorkspace>>),
-    Unit,
+    PrimeCaches(PrimeCachesProgress),
 }
 
 impl fmt::Debug for Event {
@@ -197,7 +198,28 @@ impl GlobalState {
                     }
                 }
                 Task::Workspaces(workspaces) => self.switch_workspaces(workspaces),
-                Task::Unit => (),
+                Task::PrimeCaches(progress) => {
+                    let (state, message, fraction);
+                    match progress {
+                        PrimeCachesProgress::Started => {
+                            state = Progress::Begin;
+                            message = None;
+                            fraction = 0.0;
+                        }
+                        PrimeCachesProgress::StartedOnCrate { on_crate, n_done, n_total } => {
+                            state = Progress::Report;
+                            message = Some(format!("{}/{} ({})", n_done, n_total, on_crate));
+                            fraction = Progress::fraction(n_done, n_total);
+                        }
+                        PrimeCachesProgress::Finished => {
+                            state = Progress::End;
+                            message = None;
+                            fraction = 1.0;
+                        }
+                    };
+
+                    self.report_progress("indexing", state, message, Some(fraction));
+                }
             },
             Event::Vfs(mut task) => {
                 let _p = profile::span("GlobalState::handle_event/vfs");
@@ -573,12 +595,18 @@ impl GlobalState {
                 Task::Diagnostics(diagnostics)
             })
         }
-        self.task_pool.handle.spawn({
-            let subs = subscriptions;
+        self.task_pool.handle.spawn_with_sender({
             let snap = self.snapshot();
-            move || {
-                snap.analysis.prime_caches(subs).unwrap_or_else(|_: Canceled| ());
-                Task::Unit
+            move |sender| {
+                snap.analysis
+                    .prime_caches(|progress| {
+                        sender.send(Task::PrimeCaches(progress)).unwrap();
+                    })
+                    .unwrap_or_else(|_: Canceled| {
+                        // Pretend that we're done, so that the progress bar is removed. Otherwise
+                        // the editor may complain about it already existing.
+                        sender.send(Task::PrimeCaches(PrimeCachesProgress::Finished)).unwrap()
+                    });
             }
         });
     }
diff --git a/crates/rust-analyzer/src/thread_pool.rs b/crates/rust-analyzer/src/thread_pool.rs
index 4fa502925..833893739 100644
--- a/crates/rust-analyzer/src/thread_pool.rs
+++ b/crates/rust-analyzer/src/thread_pool.rs
@@ -23,6 +23,17 @@ impl<T> TaskPool<T> {
         })
     }
 
+    pub(crate) fn spawn_with_sender<F>(&mut self, task: F)
+    where
+        F: FnOnce(Sender<T>) + Send + 'static,
+        T: Send + 'static,
+    {
+        self.inner.execute({
+            let sender = self.sender.clone();
+            move || task(sender)
+        })
+    }
+
     pub(crate) fn len(&self) -> usize {
         self.inner.queued_count()
     }
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index 3a184094c..74dbdfaf7 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -320,6 +320,10 @@ pub fn param(name: String, ty: String) -> ast::Param {
     ast_from_text(&format!("fn f({}: {}) {{ }}", name, ty))
 }
 
+pub fn ret_type(ty: ast::Type) -> ast::RetType {
+    ast_from_text(&format!("fn f() -> {} {{ }}", ty))
+}
+
 pub fn param_list(pats: impl IntoIterator<Item = ast::Param>) -> ast::ParamList {
     let args = pats.into_iter().join(", ");
     ast_from_text(&format!("fn f({}) {{ }}", args))
@@ -350,14 +354,20 @@ pub fn fn_(
     type_params: Option<ast::GenericParamList>,
     params: ast::ParamList,
     body: ast::BlockExpr,
+    ret_type: Option<ast::RetType>,
 ) -> ast::Fn {
     let type_params =
         if let Some(type_params) = type_params { format!("<{}>", type_params) } else { "".into() };
+    let ret_type = if let Some(ret_type) = ret_type { format!("{} ", ret_type) } else { "".into() };
     let visibility = match visibility {
         None => String::new(),
         Some(it) => format!("{} ", it),
     };
-    ast_from_text(&format!("{}fn {}{}{} {}", visibility, fn_name, type_params, params, body))
+
+    ast_from_text(&format!(
+        "{}fn {}{}{} {}{}",
+        visibility, fn_name, type_params, params, ret_type, body
+    ))
 }
 
 fn ast_from_text<N: AstNode>(text: &str) -> N {
diff --git a/editors/code/rust.tmGrammar.json b/editors/code/rust.tmGrammar.json
index 0be2583db..3ddd14f9c 100644
--- a/editors/code/rust.tmGrammar.json
+++ b/editors/code/rust.tmGrammar.json
@@ -1,686 +1,1043 @@
 {
-        "name": "Rust",
-        "scopeName": "source.rust",
-        "patterns": [
-                {
-                        "comment": "Implementation",
-                        "begin": "\\b(impl)\\b",
-                        "end": "\\{",
-                        "beginCaptures": {
-                                "1": {
-                                        "name": "storage.type.rust"
-                                }
-                        },
-                        "patterns": [
-                                {
-                                        "include": "#block_comment"
-                                },
-                                {
-                                        "include": "#line_comment"
-                                },
-                                {
-                                        "include": "#sigils"
-                                },
-                                {
-                                        "include": "#mut"
-                                },
-                                {
-                                        "include": "#dyn"
-                                },
-                                {
-                                        "include": "#ref_lifetime"
-                                },
-                                {
-                                        "include": "#core_types"
-                                },
-                                {
-                                        "include": "#core_marker"
-                                },
-                                {
-                                        "include": "#core_traits"
-                                },
-                                {
-                                        "include": "#std_types"
-                                },
-                                {
-                                        "include": "#std_traits"
-                                },
-                                {
-                                        "include": "#type_params"
-                                },
-                                {
-                                        "include": "#where"
-                                },
-                                {
-                                        "name": "storage.type.rust",
-                                        "match": "\\bfor\\b"
-                                },
-                                {
-                                        "include": "#type"
-                                }
-                        ]
-                },
-                {
-                        "include": "#block_doc_comment"
-                },
-                {
-                        "include": "#block_comment"
-                },
-                {
-                        "include": "#line_doc_comment"
-                },
-                {
-                        "include": "#line_comment"
-                },
-                {
-                        "comment": "Attribute",
-                        "name": "meta.attribute.rust",
-                        "begin": "#\\!?\\[(\\w*)",
-                        "end": "\\]",
-                        "captures": {
-                                "1": {
-                                        "name": "entity.name.function.attribute.rust"
-                                }
-                        },
-                        "patterns": [
-                                {
-                                        "include": "#string_literal"
-                                },
-                                {
-                                        "include": "#block_doc_comment"
-                                },
-                                {
-                                        "include": "#block_comment"
-                                },
-                                {
-                                        "include": "#line_doc_comment"
-                                },
-                                {
-                                        "include": "#line_comment"
-                                }
-                        ]
-                },
-                {
-                        "comment": "Single-quote string literal (character)",
-                        "name": "string.quoted.single.rust",
-                        "match": "b?'([^'\\\\]|\\\\(x[0-9A-Fa-f]{2}|[0-2][0-7]{0,2}|3[0-6][0-7]?|37[0-7]?|[4-7][0-7]?|.))'"
-                },
-                {
-                        "include": "#string_literal"
-                },
-                {
-                        "include": "#raw_string_literal"
-                },
-                {
-                        "comment": "Floating point literal (fraction)",
-                        "name": "constant.numeric.float.rust",
-                        "match": "\\b[0-9][0-9_]*\\.[0-9][0-9_]*([eE][+-]?[0-9_]+)?(f32|f64)?\\b"
-                },
-                {
-                        "comment": "Floating point literal (exponent)",
-                        "name": "constant.numeric.float.rust",
-                        "match": "\\b[0-9][0-9_]*(\\.[0-9][0-9_]*)?[eE][+-]?[0-9_]+(f32|f64)?\\b"
-                },
-                {
-                        "comment": "Floating point literal (typed)",
-                        "name": "constant.numeric.float.rust",
-                        "match": "\\b[0-9][0-9_]*(\\.[0-9][0-9_]*)?([eE][+-]?[0-9_]+)?(f32|f64)\\b"
-                },
-                {
-                        "comment": "Integer literal (decimal)",
-                        "name": "constant.numeric.integer.decimal.rust",
-                        "match": "\\b[0-9][0-9_]*([ui](8|16|32|64|128|s|size))?\\b"
-                },
-                {
-                        "comment": "Integer literal (hexadecimal)",
-                        "name": "constant.numeric.integer.hexadecimal.rust",
-                        "match": "\\b0x[a-fA-F0-9_]+([ui](8|16|32|64|128|s|size))?\\b"
-                },
-                {
-                        "comment": "Integer literal (octal)",
-                        "name": "constant.numeric.integer.octal.rust",
-                        "match": "\\b0o[0-7_]+([ui](8|16|32|64|128|s|size))?\\b"
-                },
-                {
-                        "comment": "Integer literal (binary)",
-                        "name": "constant.numeric.integer.binary.rust",
-                        "match": "\\b0b[01_]+([ui](8|16|32|64|128|s|size))?\\b"
-                },
-                {
-                        "comment": "Static storage modifier",
-                        "name": "storage.modifier.static.rust",
-                        "match": "\\bstatic\\b"
-                },
-                {
-                        "comment": "Boolean constant",
-                        "name": "constant.language.boolean.rust",
-                        "match": "\\b(true|false)\\b"
-                },
-                {
-                        "comment": "Control keyword",
-                        "name": "keyword.control.rust",
-                        "match": "\\b(async|await|break|continue|else|if|in|for|loop|match|return|try|while)\\b"
-                },
-                {
-                        "comment": "Keyword",
-                        "name": "keyword.other.rust",
-                        "match": "\\b(crate|extern|mod|let|ref|use|super|move|as)\\b"
-                },
-                {
-                        "comment": "Reserved keyword",
-                        "name": "invalid.deprecated.rust",
-                        "match": "\\b(abstract|alignof|become|do|final|macro|offsetof|override|priv|proc|pure|sizeof|typeof|virtual|yield)\\b"
-                },
-                {
-                        "include": "#unsafe"
-                },
-                {
-                        "include": "#sigils"
-                },
-                {
-                        "include": "#self"
-                },
-                {
-                        "include": "#mut"
-                },
-                {
-                        "include": "#dyn"
-                },
-                {
-                        "include": "#impl"
-                },
-                {
-                        "include": "#box"
-                },
-                {
-                        "include": "#lifetime"
-                },
-                {
-                        "include": "#ref_lifetime"
-                },
-                {
-                        "include": "#const"
-                },
-                {
-                        "include": "#pub"
-                },
-                {
-                        "comment": "Miscellaneous operator",
-                        "name": "keyword.operator.misc.rust",
-                        "match": "(=>|::|\\?)"
-                },
-                {
-                        "comment": "Comparison operator",
-                        "name": "keyword.operator.comparison.rust",
-                        "match": "(&&|\\|\\||==|!=)"
-                },
-                {
-                        "comment": "Assignment operator",
-                        "name": "keyword.operator.assignment.rust",
-                        "match": "(\\+=|-=|/=|\\*=|%=|\\^=|&=|\\|=|<<=|>>=|=)"
-                },
-                {
-                        "comment": "Arithmetic operator",
-                        "name": "keyword.operator.arithmetic.rust",
-                        "match": "(!|\\+|-|/|\\*|%|\\^|&|\\||<<|>>)"
-                },
-                {
-                        "comment": "Comparison operator (second group because of regex precedence)",
-                        "name": "keyword.operator.comparison.rust",
-                        "match": "(<=|>=|<|>)"
-                },
-                {
-                        "include": "#core_types"
-                },
-                {
-                        "include": "#core_vars"
-                },
-                {
-                        "include": "#core_marker"
-                },
-                {
-                        "include": "#core_traits"
-                },
-                {
-                        "include": "#std_types"
-                },
-                {
-                        "include": "#std_traits"
-                },
-                {
-                        "comment": "Built-in macro",
-                        "name": "support.function.builtin.rust",
-                        "match": "\\b(macro_rules|compile_error|format_args|env|option_env|concat_idents|concat|line|column|file|stringify|include|include_str|include_bytes|module_path|cfg)!"
-                },
-                {
-                        "comment": "Core macro",
-                        "name": "support.function.core.rust",
-                        "match": "\\b(panic|assert|assert_eq|assert_ne|debug_assert|debug_assert_eq|debug_assert_ne|try|write|writeln|unreachable|unimplemented)!"
-                },
-                {
-                        "comment": "Standard library macro",
-                        "name": "support.function.std.rust",
-                        "match": "\\b(format|print|println|eprint|eprintln|select|vec)!"
-                },
-                {
-                        "comment": "Logging macro",
-                        "name": "support.function.log.rust",
-                        "match": "\\b(log|error|warn|info|debug|trace|log_enabled)!"
-                },
-                {
-                        "comment": "Invocation of a macro",
-                        "match": "\\b([a-zA-Z_][a-zA-Z0-9_]*\\!)\\s*[({\\[]",
-                        "captures": {
-                                "1": {
-                                        "name": "entity.name.function.macro.rust"
-                                }
-                        }
-                },
-                {
-                        "comment": "Function call",
-                        "match": "\\b([A-Za-z][A-Za-z0-9_]*|_[A-Za-z0-9_]+)\\s*\\(",
-                        "captures": {
-                                "1": {
-                                        "name": "entity.name.function.rust"
-                                }
-                        }
-                },
-                {
-                        "comment": "Function call with type parameters",
-                        "begin": "\\b([A-Za-z][A-Za-z0-9_]*|_[A-Za-z0-9_]+)\\s*(::)(?=\\s*<.*>\\s*\\()",
-                        "end": "\\(",
-                        "captures": {
-                                "1": {
-                                        "name": "entity.name.function.rust"
-                                },
-                                "2": {
-                                        "name": "keyword.operator.misc.rust"
-                                }
-                        },
-                        "patterns": [
-                                {
-                                        "include": "#type_params"
-                                }
-                        ]
-                },
-                {
-                        "comment": "Function definition",
-                        "begin": "\\b(fn)\\s+([A-Za-z][A-Za-z0-9_]*|_[A-Za-z0-9_]+)",
-                        "end": "[\\{;]",
-                        "beginCaptures": {
-                                "1": {
-                                        "name": "keyword.other.fn.rust"
-                                },
-                                "2": {
-                                        "name": "entity.name.function.rust"
-                                }
-                        },
-                        "patterns": [
-                                {
-                                        "include": "#block_comment"
-                                },
-                                {
-                                        "include": "#line_comment"
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+                }
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+                    "name": "constant.other.caps.rust",
+                    "match": "\\b[A-Z]{2}[A-Z0-9_]*\\b"
+                },
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+                        },
+                        "5": {
+                            "name": "punctuation.brackets.angle.rust"
+                        }
+                    },
+                    "end": "\\{",
+                    "endCaptures": {
+                        "0": {
+                            "name": "punctuation.brackets.curly.rust"
+                        }
+                    },
+                    "patterns": [
+                        {
+                            "include": "#comments"
+                        },
+                        {
+                            "include": "#keywords"
+                        },
+                        {
+                            "include": "#lvariables"
+                        },
+                        {
+                            "include": "#constants"
+                        },
+                        {
+                            "include": "#gtypes"
+                        },
+                        {
+                            "include": "#functions"
+                        },
+                        {
+                            "include": "#lifetimes"
+                        },
+                        {
+                            "include": "#macros"
+                        },
+                        {
+                            "include": "#namespaces"
+                        },
+                        {
+                            "include": "#punctuation"
+                        },
+                        {
+                            "include": "#strings"
+                        },
+                        {
+                            "include": "#types"
+                        },
+                        {
+                            "include": "#variables"
+                        }
+                    ]
+                },
+                {
+                    "comment": "function/method calls, chaining",
+                    "name": "meta.function.call.rust",
+                    "begin": "(?:(pub)|(?:(\\.)?([A-Za-z0-9_]+)))(\\()",
+                    "beginCaptures": {
+                        "1": {
+                            "name": "keyword.other.rust"
+                        },
+                        "2": {
+                            "name": "keyword.operator.access.dot.rust"
+                        },
+                        "3": {
+                            "name": "entity.name.function.rust"
+                        },
+                        "4": {
+                            "name": "punctuation.brackets.round.rust"
+                        }
+                    },
+                    "end": "\\)",
+                    "endCaptures": {
+                        "0": {
+                            "name": "punctuation.brackets.round.rust"
+                        }
+                    },
+                    "patterns": [
+                        {
+                            "include": "#comments"
+                        },
+                        {
+                            "include": "#keywords"
+                        },
+                        {
+                            "include": "#lvariables"
+                        },
+                        {
+                            "include": "#namespaces"
+                        },
+                        {
+                            "include": "#constants"
+                        },
+                        {
+                            "include": "#gtypes"
+                        },
+                        {
+                            "include": "#functions"
+                        },
+                        {
+                            "include": "#lifetimes"
+                        },
+                        {
+                            "include": "#macros"
+                        },
+                        {
+                            "include": "#punctuation"
+                        },
+                        {
+                            "include": "#strings"
+                        },
+                        {
+                            "include": "#types"
+                        },
+                        {
+                            "include": "#variables"
+                        }
+                    ]
+                }
+            ]
+        },
+        "keywords": {
+            "patterns": [
+                {
+                    "comment": "control flow keywords",
+                    "name": "keyword.control.rust",
+                    "match": "\\b(async|await|break|continue|do|else|for|if|loop|match|move|return|try|where|while|yield)\\b"
+                },
+                {
+                    "comment": "storage keywords",
+                    "name": "storage.type.rust",
+                    "match": "\\b(const|enum|extern|let|macro|mod|struct|trait|type)\\b"
+                },
+                {
+                    "comment": "storage modifiers",
+                    "name": "storage.modifier.rust",
+                    "match": "\\b(abstract|static)\\b"
+                },
+                {
+                    "comment": "other keywords",
+                    "name": "keyword.other.rust",
+                    "match": "\\b(as|become|box|dyn|final|impl|in|override|priv|pub|ref|typeof|union|unsafe|unsized|use|virtual)\\b"
+                },
+                {
+                    "comment": "fn",
+                    "name": "keyword.other.fn.rust",
+                    "match": "\\bfn\\b"
+                },
+                {
+                    "comment": "crate",
+                    "name": "keyword.other.crate.rust",
+                    "match": "\\bcrate\\b"
+                },
+                {
+                    "comment": "mut",
+                    "name": "storage.modifier.mut.rust",
+                    "match": "\\bmut\\b"
+                },
+                {
+                    "comment": "math operators",
+                    "name": "keyword.operator.math.rust",
+                    "match": "(([+%]|(\\*(?!\\w)))(?!=))|(-(?!>))|(/(?!/))"
+                },
+                {
+                    "comment": "logical operators",
+                    "name": "keyword.operator.logical.rust",
+                    "match": "(\\^|\\||\\|\\||&&|<<|>>|!)(?!=)"
+                },
+                {
+                    "comment": "logical AND, borrow references",
+                    "name": "keyword.operator.borrow.and.rust",
+                    "match": "&(?![&=])"
+                },
+                {
+                    "comment": "assignment operators",
+                    "name": "keyword.operator.assignment.rust",
+                    "match": "(-=|\\*=|/=|%=|\\^=|&=|\\|=|<<=|>>=)"
+                },
+                {
+                    "comment": "single equal",
+                    "name": "keyword.operator.assignment.equal.rust",
+                    "match": "(?<![<>])=(?!=|>)"
+                },
+                {
+                    "comment": "comparison operators",
+                    "name": "keyword.operator.comparison.rust",
+                    "match": "(=(=)?(?!>)|!=|<=|(?<!=)>=)"
+                },
+                {
+                    "comment": "less than, greater than (special case)",
+                    "match": "(^|\\s)(?<!=)([<>])\\s",
+                    "captures": {
+                        "2": {
+                            "name": "keyword.operator.comparison.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "namespace operator",
+                    "name": "keyword.operator.namespace.rust",
+                    "match": "::"
+                },
+                {
+                    "comment": "dereference asterisk",
+                    "match": "(\\*)(?=\\w+)",
+                    "captures": {
+                        "1": {
+                            "name": "keyword.operator.dereference.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "subpattern binding",
+                    "name": "keyword.operator.subpattern.rust",
+                    "match": "@"
+                },
+                {
+                    "comment": "dot access",
+                    "name": "keyword.operator.access.dot.rust",
+                    "match": "\\.(?!\\.)"
+                },
+                {
+                    "comment": "ranges, range patterns",
+                    "name": "keyword.operator.range.rust",
+                    "match": "\\.{2}(=|\\.)?"
+                },
+                {
+                    "comment": "colon",
+                    "name": "keyword.operator.key-value.rust",
+                    "match": ":(?!:)"
+                },
+                {
+                    "comment": "dashrocket, skinny arrow",
+                    "name": "keyword.operator.arrow.skinny.rust",
+                    "match": "->"
+                },
+                {
+                    "comment": "hashrocket, fat arrow",
+                    "name": "keyword.operator.arrow.fat.rust",
+                    "match": "=>"
+                },
+                {
+                    "comment": "dollar macros",
+                    "name": "keyword.operator.macro.dollar.rust",
+                    "match": "\\$"
+                },
+                {
+                    "comment": "question mark operator, questionably sized, macro kleene matcher",
+                    "name": "keyword.operator.question.rust",
+                    "match": "\\?"
+                }
+            ]
+        },
+        "interpolations": {
+            "comment": "curly brace interpolations",
+            "name": "meta.interpolation.rust",
+            "begin": "{",
+            "beginCaptures": {
+                "0": {
+                    "name": "punctuation.definition.interpolation.rust"
+                }
+            },
+            "end": "}",
+            "endCaptures": {
+                "0": {
+                    "name": "punctuation.definition.interpolation.rust"
+                }
+            },
+            "patterns": [
+                {
+                    "include": "#interpolations"
+                }
+            ]
+        },
+        "lifetimes": {
+            "patterns": [
+                {
+                    "comment": "named lifetime parameters",
+                    "match": "(['])([a-zA-Z_][0-9a-zA-Z_]*)(?!['])\\b",
+                    "captures": {
+                        "1": {
+                            "name": "punctuation.definition.lifetime.rust"
+                        },
+                        "2": {
+                            "name": "entity.name.type.lifetime.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "borrowing references to named lifetimes",
+                    "match": "(\\&)(['])([a-zA-Z_][0-9a-zA-Z_]*)(?!['])\\b",
+                    "captures": {
+                        "1": {
+                            "name": "keyword.operator.borrow.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.definition.lifetime.rust"
+                        },
+                        "3": {
+                            "name": "entity.name.type.lifetime.rust"
+                        }
+                    }
+                }
+            ]
+        },
+        "macros": {
+            "patterns": [
+                {
+                    "comment": "macros",
+                    "name": "meta.macro.rust",
+                    "match": "(([a-z_][A-Za-z0-9_]*!)|([A-Z_][A-Za-z0-9_]*!))",
+                    "captures": {
+                        "2": {
+                            "name": "entity.name.function.macro.rust"
+                        },
+                        "3": {
+                            "name": "entity.name.type.macro.rust"
+                        }
+                    }
+                }
+            ]
+        },
+        "namespaces": {
+            "patterns": [
+                {
+                    "comment": "namespace (non-type, non-function path segment)",
+                    "match": "(?<![A-Za-z0-9_])([a-z0-9_]+)((?<!super|self)::)",
+                    "captures": {
+                        "1": {
+                            "name": "entity.name.namespace.rust"
+                        },
+                        "2": {
+                            "name": "keyword.operator.namespace.rust"
+                        }
+                    }
+                }
+            ]
+        },
+        "types": {
+            "patterns": [
+                {
+                    "comment": "numeric types",
+                    "match": "(?<![A-Za-z])(f32|f64|i128|i16|i32|i64|i8|isize|u128|u16|u32|u64|u8|usize)\\b",
+                    "captures": {
+                        "1": {
+                            "name": "entity.name.type.numeric.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "parameterized types",
+                    "begin": "\\b([A-Z][A-Za-z0-9]*)(<)",
+                    "beginCaptures": {
+                        "1": {
+                            "name": "entity.name.type.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.brackets.angle.rust"
+                        }
+                    },
+                    "end": ">",
+                    "endCaptures": {
+                        "0": {
+                            "name": "punctuation.brackets.angle.rust"
+                        }
+                    },
+                    "patterns": [
+                        {
+                            "include": "#comments"
+                        },
+                        {
+                            "include": "#keywords"
+                        },
+                        {
+                            "include": "#lvariables"
+                        },
+                        {
+                            "include": "#lifetimes"
+                        },
+                        {
+                            "include": "#punctuation"
+                        },
+                        {
+                            "include": "#types"
+                        },
+                        {
+                            "include": "#variables"
+                        }
+                    ]
+                },
+                {
+                    "comment": "primitive types",
+                    "name": "entity.name.type.primitive.rust",
+                    "match": "\\b(bool|char|str)\\b"
+                },
+                {
+                    "comment": "trait declarations",
+                    "match": "\\b(trait)\\s+([A-Z][A-Za-z0-9]*)\\b",
+                    "captures": {
+                        "1": {
+                            "name": "storage.type.rust"
+                        },
+                        "2": {
+                            "name": "entity.name.type.trait.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "struct declarations",
+                    "match": "\\b(struct)\\s+([A-Z][A-Za-z0-9]*)\\b",
+                    "captures": {
+                        "1": {
+                            "name": "storage.type.rust"
+                        },
+                        "2": {
+                            "name": "entity.name.type.struct.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "enum declarations",
+                    "match": "\\b(enum)\\s+([A-Z][A-Za-z0-9_]*)\\b",
+                    "captures": {
+                        "1": {
+                            "name": "storage.type.rust"
+                        },
+                        "2": {
+                            "name": "entity.name.type.enum.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "type declarations",
+                    "match": "\\b(type)\\s+([A-Z][A-Za-z0-9_]*)\\b",
+                    "captures": {
+                        "1": {
+                            "name": "storage.type.rust"
+                        },
+                        "2": {
+                            "name": "entity.name.type.declaration.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "types",
+                    "name": "entity.name.type.rust",
+                    "match": "\\b[A-Z][A-Za-z0-9]*\\b(?!!)"
+                }
+            ]
+        },
+        "gtypes": {
+            "patterns": [
+                {
+                    "comment": "option types",
+                    "name": "entity.name.type.option.rust",
+                    "match": "\\b(Some|None)\\b"
+                },
+                {
+                    "comment": "result types",
+                    "name": "entity.name.type.result.rust",
+                    "match": "\\b(Ok|Err)\\b"
+                }
+            ]
+        },
+        "punctuation": {
+            "patterns": [
+                {
+                    "comment": "comma",
+                    "name": "punctuation.comma.rust",
+                    "match": ","
+                },
+                {
+                    "comment": "curly braces",
+                    "name": "punctuation.brackets.curly.rust",
+                    "match": "[{}]"
+                },
+                {
+                    "comment": "parentheses, round brackets",
+                    "name": "punctuation.brackets.round.rust",
+                    "match": "[()]"
+                },
+                {
+                    "comment": "semicolon",
+                    "name": "punctuation.semi.rust",
+                    "match": ";"
+                },
+                {
+                    "comment": "square brackets",
+                    "name": "punctuation.brackets.square.rust",
+                    "match": "[\\[\\]]"
+                },
+                {
+                    "comment": "angle brackets",
+                    "name": "punctuation.brackets.angle.rust",
+                    "match": "(?<!=)[<>]"
+                }
+            ]
+        },
+        "strings": {
+            "patterns": [
+                {
+                    "comment": "double-quoted strings and byte strings",
+                    "name": "string.quoted.double.rust",
+                    "begin": "(b?)(\")",
+                    "beginCaptures": {
+                        "1": {
+                            "name": "string.quoted.byte.raw.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.definition.string.rust"
+                        }
+                    },
+                    "end": "\"",
+                    "endCaptures": {
+                        "0": {
+                            "name": "punctuation.definition.string.rust"
+                        }
+                    },
+                    "patterns": [
+                        {
+                            "include": "#escapes"
+                        },
+                        {
+                            "include": "#interpolations"
+                        }
+                    ]
+                },
+                {
+                    "comment": "double-quoted raw strings and raw byte strings",
+                    "name": "string.quoted.double.rust",
+                    "begin": "(b?r)(#*)(\")",
+                    "beginCaptures": {
+                        "1": {
+                            "name": "string.quoted.byte.raw.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.definition.string.raw.rust"
+                        },
+                        "3": {
+                            "name": "punctuation.definition.string.rust"
+                        }
+                    },
+                    "end": "(\")(#*)",
+                    "endCaptures": {
+                        "1": {
+                            "name": "punctuation.definition.string.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.definition.string.raw.rust"
+                        }
+                    }
+                },
+                {
+                    "comment": "characters and bytes",
+                    "name": "string.quoted.single.char.rust",
+                    "begin": "(b)?(')",
+                    "beginCaptures": {
+                        "1": {
+                            "name": "string.quoted.byte.raw.rust"
+                        },
+                        "2": {
+                            "name": "punctuation.definition.char.rust"
+                        }
+                    },
+                    "end": "'",
+                    "endCaptures": {
+                        "0": {
+                            "name": "punctuation.definition.char.rust"
+                        }
+                    },
+                    "patterns": [
+                        {
+                            "include": "#escapes"
+                        }
+                    ]
+                }
+            ]
+        },
+        "lvariables": {
+            "patterns": [
+                {
+                    "comment": "self",
+                    "name": "variable.language.self.rust",
+                    "match": "\\b[Ss]elf\\b"
+                },
+                {
+                    "comment": "super",
+                    "name": "variable.language.super.rust",
+                    "match": "\\bsuper\\b"
+                }
+            ]
+        },
+        "variables": {
+            "patterns": [
+                {
+                    "comment": "variables",
+                    "name": "variable.other.rust",
+                    "match": "\\b(?<!\\.)[a-z0-9_]+\\b"
+                }
+            ]
+        }
+    }
 }