Merge branch 'master' of github.com:rust-analyzer/rust-analyzer

68 files changed, 1928 insertions, 592 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 2c1192f07..3f52f31f8 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -39,7 +39,6 @@ jobs:
       with:
         toolchain: stable
         profile: minimal
-        target: x86_64-unknown-linux-musl
         override: true
 
     - name: Install Nodejs
diff --git a/.vscode/launch.json b/.vscode/launch.json
index 3f74d7566..6a2fff906 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -41,7 +41,7 @@
       "outFiles": [
         "${workspaceFolder}/editors/code/out/**/*.js"
       ],
-      "preLaunchTask": "Build Extension",
+      "preLaunchTask": "Build Server and Extension",
       "skipFiles": [
         "<node_internals>/**/*.js"
       ],
@@ -62,7 +62,7 @@
       "outFiles": [
         "${workspaceFolder}/editors/code/out/**/*.js"
       ],
-      "preLaunchTask": "Build Extension",
+      "preLaunchTask": "Build Server (Release) and Extension",
       "skipFiles": [
         "<node_internals>/**/*.js"
       ],
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index 4037e7cce..0969ce89a 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -4,7 +4,7 @@
   "version": "2.0.0",
   "tasks": [
     {
-      "label": "Build Extension",
+      "label": "Build Extension in Background",
       "group": "build",
       "type": "npm",
       "script": "watch",
@@ -16,11 +16,40 @@
       "isBackground": true,
     },
     {
+      "label": "Build Extension",
+      "group": "build",
+      "type": "npm",
+      "script": "build",
+      "path": "editors/code/",
+      "problemMatcher": {
+        "base": "$tsc",
+        "fileLocation": ["relative", "${workspaceFolder}/editors/code/"]
+      },
+    },
+    {
       "label": "Build Server",
       "group": "build",
       "type": "shell",
       "command": "cargo build --package rust-analyzer",
       "problemMatcher": "$rustc"
     },
+    {
+      "label": "Build Server (Release)",
+      "group": "build",
+      "type": "shell",
+      "command": "cargo build --release --package rust-analyzer",
+      "problemMatcher": "$rustc"
+    },
+
+    {
+      "label": "Build Server and Extension",
+      "dependsOn": ["Build Server", "Build Extension"],
+      "problemMatcher": "$rustc"
+    },
+    {
+      "label": "Build Server (Release) and Extension",
+      "dependsOn": ["Build Server (Release)", "Build Extension"],
+      "problemMatcher": "$rustc"
+    }
   ]
 }
diff --git a/Cargo.lock b/Cargo.lock
index 367ff3f82..522ecf2ee 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -68,9 +68,9 @@ dependencies = [
 
 [[package]]
 name = "base64"
-version = "0.11.0"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b41b7ea54a0c9d92199de89e20e58d49f02f8e699814ef3fdf266f6f748d15c7"
+checksum = "7d5ca2cd0adc3f48f9e9ea5a6bbdf9ccc0bfade884847e484d452414c7ccffb3"
 
 [[package]]
 name = "bitflags"
@@ -645,9 +645,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-types"
-version = "0.73.0"
+version = "0.74.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "93d0cf64ea141b43d9e055f6b9df13f0bce32b103d84237509ce0a571ab9b159"
+checksum = "820f746e5716ab9a2d664794636188bd003023b72e55404ee27105dc22869922"
 dependencies = [
  "base64",
  "bitflags",
@@ -1193,9 +1193,9 @@ dependencies = [
 
 [[package]]
 name = "ra_vfs"
-version = "0.5.3"
+version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58a265769d5e5655345a9fcbd870a1a7c3658558c0d8efaed79e0669358f46b8"
+checksum = "fcaa5615f420134aea7667253db101d03a5c5f300eac607872dc2a36407b2ac9"
 dependencies = [
  "crossbeam-channel",
  "jod-thread",
diff --git a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
index 03806724a..49deb6701 100644
--- a/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
+++ b/crates/ra_assists/src/handlers/add_from_impl_for_enum.rs
@@ -1,11 +1,12 @@
+use ra_ide_db::RootDatabase;
 use ra_syntax::{
     ast::{self, AstNode, NameOwner},
     TextSize,
 };
 use stdx::format_to;
 
-use crate::{Assist, AssistCtx, AssistId};
-use ra_ide_db::RootDatabase;
+use crate::{utils::FamousDefs, Assist, AssistCtx, AssistId};
+use test_utils::tested_by;
 
 // Assist add_from_impl_for_enum
 //
@@ -41,7 +42,8 @@ pub(crate) fn add_from_impl_for_enum(ctx: AssistCtx) -> Option<Assist> {
         _ => return None,
     };
 
-    if already_has_from_impl(ctx.sema, &variant) {
+    if existing_from_impl(ctx.sema, &variant).is_some() {
+        tested_by!(test_add_from_impl_already_exists);
         return None;
     }
 
@@ -70,41 +72,33 @@ impl From<{0}> for {1} {{
     )
 }
 
-fn already_has_from_impl(
+fn existing_from_impl(
     sema: &'_ hir::Semantics<'_, RootDatabase>,
     variant: &ast::EnumVariant,
-) -> bool {
-    let scope = sema.scope(&variant.syntax());
+) -> Option<()> {
+    let variant = sema.to_def(variant)?;
+    let enum_ = variant.parent_enum(sema.db);
+    let krate = enum_.module(sema.db).krate();
 
-    let from_path = ast::make::path_from_text("From");
-    let from_hir_path = match hir::Path::from_ast(from_path) {
-        Some(p) => p,
-        None => return false,
-    };
-    let from_trait = match scope.resolve_hir_path(&from_hir_path) {
-        Some(hir::PathResolution::Def(hir::ModuleDef::Trait(t))) => t,
-        _ => return false,
-    };
+    let from_trait = FamousDefs(sema, krate).core_convert_From()?;
 
-    let e: hir::Enum = match sema.to_def(&variant.parent_enum()) {
-        Some(e) => e,
-        None => return false,
-    };
-    let e_ty = e.ty(sema.db);
+    let enum_type = enum_.ty(sema.db);
 
-    let hir_enum_var: hir::EnumVariant = match sema.to_def(variant) {
-        Some(ev) => ev,
-        None => return false,
-    };
-    let var_ty = hir_enum_var.fields(sema.db)[0].signature_ty(sema.db);
+    let wrapped_type = variant.fields(sema.db).get(0)?.signature_ty(sema.db);
 
-    e_ty.impls_trait(sema.db, from_trait, &[var_ty])
+    if enum_type.impls_trait(sema.db, from_trait, &[wrapped_type]) {
+        Some(())
+    } else {
+        None
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
+
     use crate::helpers::{check_assist, check_assist_not_applicable};
+    use test_utils::covers;
 
     #[test]
     fn test_add_from_impl_for_enum() {
@@ -136,36 +130,40 @@ mod tests {
         );
     }
 
+    fn check_not_applicable(ra_fixture: &str) {
+        let fixture =
+            format!("//- main.rs crate:main deps:core\n{}\n{}", ra_fixture, FamousDefs::FIXTURE);
+        check_assist_not_applicable(add_from_impl_for_enum, &fixture)
+    }
+
     #[test]
     fn test_add_from_impl_no_element() {
-        check_assist_not_applicable(add_from_impl_for_enum, "enum A { <|>One }");
+        check_not_applicable("enum A { <|>One }");
     }
 
     #[test]
     fn test_add_from_impl_more_than_one_element_in_tuple() {
-        check_assist_not_applicable(add_from_impl_for_enum, "enum A { <|>One(u32, String) }");
+        check_not_applicable("enum A { <|>One(u32, String) }");
     }
 
     #[test]
     fn test_add_from_impl_struct_variant() {
-        check_assist_not_applicable(add_from_impl_for_enum, "enum A { <|>One { x: u32 } }");
+        check_not_applicable("enum A { <|>One { x: u32 } }");
     }
 
     #[test]
     fn test_add_from_impl_already_exists() {
-        check_assist_not_applicable(
-            add_from_impl_for_enum,
-            r#"enum A { <|>One(u32), }
+        covers!(test_add_from_impl_already_exists);
+        check_not_applicable(
+            r#"
+enum A { <|>One(u32), }
 
 impl From<u32> for A {
     fn from(v: u32) -> Self {
         A::One(v)
     }
 }
-
-pub trait From<T> {
-    fn from(T) -> Self;
-}"#,
+"#,
         );
     }
 
diff --git a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
index 0a0a88f3d..9841f6980 100644
--- a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
@@ -1,11 +1,10 @@
 use ra_fmt::unwrap_trivial_block;
 use ra_syntax::{
-    ast::{self, make},
+    ast::{self, edit::IndentLevel, make},
     AstNode,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
-use ast::edit::IndentLevel;
+use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
 
 // Assist: replace_if_let_with_match
 //
@@ -44,15 +43,21 @@ pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
         ast::ElseBranch::IfExpr(_) => return None,
     };
 
-    ctx.add_assist(AssistId("replace_if_let_with_match"), "Replace with match", |edit| {
+    let sema = ctx.sema;
+    ctx.add_assist(AssistId("replace_if_let_with_match"), "Replace with match", move |edit| {
         let match_expr = {
             let then_arm = {
                 let then_expr = unwrap_trivial_block(then_block);
-                make::match_arm(vec![pat], then_expr)
+                make::match_arm(vec![pat.clone()], then_expr)
             };
             let else_arm = {
+                let pattern = sema
+                    .type_of_pat(&pat)
+                    .and_then(|ty| TryEnum::from_ty(sema, &ty))
+                    .map(|it| it.sad_pattern())
+                    .unwrap_or_else(|| make::placeholder_pat().into());
                 let else_expr = unwrap_trivial_block(else_block);
-                make::match_arm(vec![make::placeholder_pat().into()], else_expr)
+                make::match_arm(vec![pattern], else_expr)
             };
             make::expr_match(expr, make::match_arm_list(vec![then_arm, else_arm]))
         };
@@ -68,6 +73,7 @@ pub(crate) fn replace_if_let_with_match(ctx: AssistCtx) -> Option<Assist> {
 #[cfg(test)]
 mod tests {
     use super::*;
+
     use crate::helpers::{check_assist, check_assist_target};
 
     #[test]
@@ -145,4 +151,64 @@ impl VariantData {
         }",
         );
     }
+
+    #[test]
+    fn special_case_option() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    <|>if let Some(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    <|>match x {
+        Some(x) => println!("{}", x),
+        None => println!("none"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
+    fn special_case_result() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    <|>if let Ok(x) = x {
+        println!("{}", x)
+    } else {
+        println!("none")
+    }
+}
+           "#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    <|>match x {
+        Ok(x) => println!("{}", x),
+        Err(_) => println!("none"),
+    }
+}
+           "#,
+        );
+    }
 }
diff --git a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
index bdbaae389..0cf23b754 100644
--- a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
+++ b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
@@ -1,6 +1,5 @@
 use std::iter::once;
 
-use hir::Adt;
 use ra_syntax::{
     ast::{
         self,
@@ -12,6 +11,7 @@ use ra_syntax::{
 
 use crate::{
     assist_ctx::{Assist, AssistCtx},
+    utils::TryEnum,
     AssistId,
 };
 
@@ -45,20 +45,10 @@ pub(crate) fn replace_let_with_if_let(ctx: AssistCtx) -> Option<Assist> {
     let init = let_stmt.initializer()?;
     let original_pat = let_stmt.pat()?;
     let ty = ctx.sema.type_of_expr(&init)?;
-    let enum_ = match ty.as_adt() {
-        Some(Adt::Enum(it)) => it,
-        _ => return None,
-    };
-    let happy_case =
-        [("Result", "Ok"), ("Option", "Some")].iter().find_map(|(known_type, happy_case)| {
-            if &enum_.name(ctx.db).to_string() == known_type {
-                return Some(happy_case);
-            }
-            None
-        });
+    let happy_variant = TryEnum::from_ty(ctx.sema, &ty).map(|it| it.happy_case());
 
     ctx.add_assist(AssistId("replace_let_with_if_let"), "Replace with if-let", |edit| {
-        let with_placeholder: ast::Pat = match happy_case {
+        let with_placeholder: ast::Pat = match happy_variant {
             None => make::placeholder_pat().into(),
             Some(var_name) => make::tuple_struct_pat(
                 make::path_unqualified(make::path_segment(make::name_ref(var_name))),
diff --git a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
index 62cb7a763..62d4ea522 100644
--- a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
@@ -1,12 +1,11 @@
 use std::iter;
 
 use ra_syntax::{
-    ast::{self, make},
+    ast::{self, edit::IndentLevel, make},
     AstNode,
 };
 
-use crate::{Assist, AssistCtx, AssistId};
-use ast::edit::IndentLevel;
+use crate::{utils::TryEnum, Assist, AssistCtx, AssistId};
 
 // Assist: replace_unwrap_with_match
 //
@@ -38,42 +37,27 @@ pub(crate) fn replace_unwrap_with_match(ctx: AssistCtx) -> Option<Assist> {
     }
     let caller = method_call.expr()?;
     let ty = ctx.sema.type_of_expr(&caller)?;
+    let happy_variant = TryEnum::from_ty(ctx.sema, &ty)?.happy_case();
 
-    let type_name = ty.as_adt()?.name(ctx.sema.db).to_string();
+    ctx.add_assist(AssistId("replace_unwrap_with_match"), "Replace unwrap with match", |edit| {
+        let ok_path = make::path_unqualified(make::path_segment(make::name_ref(happy_variant)));
+        let it = make::bind_pat(make::name("a")).into();
+        let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
 
-    for (unwrap_type, variant_name) in [("Result", "Ok"), ("Option", "Some")].iter() {
-        if &type_name == unwrap_type {
-            return ctx.add_assist(
-                AssistId("replace_unwrap_with_match"),
-                "Replace unwrap with match",
-                |edit| {
-                    let ok_path =
-                        make::path_unqualified(make::path_segment(make::name_ref(variant_name)));
-                    let it = make::bind_pat(make::name("a")).into();
-                    let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
+        let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
+        let ok_arm = make::match_arm(iter::once(ok_tuple), make::expr_path(bind_path));
 
-                    let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
-                    let ok_arm = make::match_arm(iter::once(ok_tuple), make::expr_path(bind_path));
+        let unreachable_call = make::unreachable_macro_call().into();
+        let err_arm = make::match_arm(iter::once(make::placeholder_pat().into()), unreachable_call);
 
-                    let unreachable_call = make::unreachable_macro_call().into();
-                    let err_arm = make::match_arm(
-                        iter::once(make::placeholder_pat().into()),
-                        unreachable_call,
-                    );
+        let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
+        let match_expr = make::expr_match(caller.clone(), match_arm_list);
+        let match_expr = IndentLevel::from_node(method_call.syntax()).increase_indent(match_expr);
 
-                    let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
-                    let match_expr = make::expr_match(caller.clone(), match_arm_list);
-                    let match_expr =
-                        IndentLevel::from_node(method_call.syntax()).increase_indent(match_expr);
-
-                    edit.target(method_call.syntax().text_range());
-                    edit.set_cursor(caller.syntax().text_range().start());
-                    edit.replace_ast::<ast::Expr>(method_call.into(), match_expr);
-                },
-            );
-        }
-    }
-    None
+        edit.target(method_call.syntax().text_range());
+        edit.set_cursor(caller.syntax().text_range().start());
+        edit.replace_ast::<ast::Expr>(method_call.into(), match_expr);
+    })
 }
 
 #[cfg(test)]
diff --git a/crates/ra_assists/src/marks.rs b/crates/ra_assists/src/marks.rs
index 6c2a2b8b6..8d910205f 100644
--- a/crates/ra_assists/src/marks.rs
+++ b/crates/ra_assists/src/marks.rs
@@ -8,4 +8,5 @@ test_utils::marks![
     test_not_inline_mut_variable
     test_not_applicable_if_variable_unused
     change_visibility_field_false_positive
+    test_add_from_impl_already_exists
 ];
diff --git a/crates/ra_assists/src/utils.rs b/crates/ra_assists/src/utils.rs
index 3d6c59bda..efd988697 100644
--- a/crates/ra_assists/src/utils.rs
+++ b/crates/ra_assists/src/utils.rs
@@ -1,7 +1,9 @@
 //! Assorted functions shared by several assists.
 pub(crate) mod insert_use;
 
-use hir::Semantics;
+use std::iter;
+
+use hir::{Adt, Crate, Semantics, Trait, Type};
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
     ast::{self, make, NameOwner},
@@ -99,3 +101,109 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
         _ => None,
     }
 }
+
+#[derive(Clone, Copy)]
+pub(crate) enum TryEnum {
+    Result,
+    Option,
+}
+
+impl TryEnum {
+    const ALL: [TryEnum; 2] = [TryEnum::Option, TryEnum::Result];
+
+    pub(crate) fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
+        let enum_ = match ty.as_adt() {
+            Some(Adt::Enum(it)) => it,
+            _ => return None,
+        };
+        TryEnum::ALL.iter().find_map(|&var| {
+            if &enum_.name(sema.db).to_string() == var.type_name() {
+                return Some(var);
+            }
+            None
+        })
+    }
+
+    pub(crate) fn happy_case(self) -> &'static str {
+        match self {
+            TryEnum::Result => "Ok",
+            TryEnum::Option => "Some",
+        }
+    }
+
+    pub(crate) fn sad_pattern(self) -> ast::Pat {
+        match self {
+            TryEnum::Result => make::tuple_struct_pat(
+                make::path_unqualified(make::path_segment(make::name_ref("Err"))),
+                iter::once(make::placeholder_pat().into()),
+            )
+            .into(),
+            TryEnum::Option => make::bind_pat(make::name("None")).into(),
+        }
+    }
+
+    fn type_name(self) -> &'static str {
+        match self {
+            TryEnum::Result => "Result",
+            TryEnum::Option => "Option",
+        }
+    }
+}
+
+/// Helps with finding well-know things inside the standard library. This is
+/// somewhat similar to the known paths infra inside hir, but it different; We
+/// want to make sure that IDE specific paths don't become interesting inside
+/// the compiler itself as well.
+pub(crate) struct FamousDefs<'a, 'b>(pub(crate) &'a Semantics<'b, RootDatabase>, pub(crate) Crate);
+
+#[allow(non_snake_case)]
+impl FamousDefs<'_, '_> {
+    #[cfg(test)]
+    pub(crate) const FIXTURE: &'static str = r#"
+//- /libcore.rs crate:core
+pub mod convert{
+    pub trait From<T> {
+        fn from(T) -> Self;
+    }
+}
+
+pub mod prelude { pub use crate::convert::From }
+#[prelude_import]
+pub use prelude::*;
+"#;
+
+    pub(crate) fn core_convert_From(&self) -> Option<Trait> {
+        self.find_trait("core:convert:From")
+    }
+
+    fn find_trait(&self, path: &str) -> Option<Trait> {
+        let db = self.0.db;
+        let mut path = path.split(':');
+        let trait_ = path.next_back()?;
+        let std_crate = path.next()?;
+        let std_crate = self
+            .1
+            .dependencies(db)
+            .into_iter()
+            .find(|dep| &dep.name.to_string() == std_crate)?
+            .krate;
+
+        let mut module = std_crate.root_module(db)?;
+        for segment in path {
+            module = module.children(db).find_map(|child| {
+                let name = child.name(db)?;
+                if &name.to_string() == segment {
+                    Some(child)
+                } else {
+                    None
+                }
+            })?;
+        }
+        let def =
+            module.scope(db, None).into_iter().find(|(name, _def)| &name.to_string() == trait_)?.1;
+        match def {
+            hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
+            _ => None,
+        }
+    }
+}
diff --git a/crates/ra_flycheck/Cargo.toml b/crates/ra_flycheck/Cargo.toml
index 76e5cada4..324c33d9d 100644
--- a/crates/ra_flycheck/Cargo.toml
+++ b/crates/ra_flycheck/Cargo.toml
@@ -6,7 +6,7 @@ authors = ["rust-analyzer developers"]
 
 [dependencies]
 crossbeam-channel = "0.4.0"
-lsp-types = { version = "0.73.0", features = ["proposed"] }
+lsp-types = { version = "0.74.0", features = ["proposed"] }
 log = "0.4.8"
 cargo_metadata = "0.9.1"
 serde_json = "1.0.48"
diff --git a/crates/ra_fmt/src/lib.rs b/crates/ra_fmt/src/lib.rs
index 0b4ba1bbe..1a30b2b3a 100644
--- a/crates/ra_fmt/src/lib.rs
+++ b/crates/ra_fmt/src/lib.rs
@@ -57,18 +57,17 @@ pub fn extract_trivial_expression(block: &ast::BlockExpr) -> Option<ast::Expr> {
             return None;
         }
         return Some(expr);
-    } else {
-        // Unwrap `{ continue; }`
-        let (stmt,) = block.statements().next_tuple()?;
-        if let ast::Stmt::ExprStmt(expr_stmt) = stmt {
-            if has_anything_else(expr_stmt.syntax()) {
-                return None;
-            }
-            let expr = expr_stmt.expr()?;
-            match expr.syntax().kind() {
-                CONTINUE_EXPR | BREAK_EXPR | RETURN_EXPR => return Some(expr),
-                _ => (),
-            }
+    }
+    // Unwrap `{ continue; }`
+    let (stmt,) = block.statements().next_tuple()?;
+    if let ast::Stmt::ExprStmt(expr_stmt) = stmt {
+        if has_anything_else(expr_stmt.syntax()) {
+            return None;
+        }
+        let expr = expr_stmt.expr()?;
+        match expr.syntax().kind() {
+            CONTINUE_EXPR | BREAK_EXPR | RETURN_EXPR => return Some(expr),
+            _ => (),
         }
     }
     None
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index fb788736d..af59aa1b6 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -953,6 +953,16 @@ impl TypeParam {
     pub fn module(self, db: &dyn HirDatabase) -> Module {
         self.id.parent.module(db.upcast()).into()
     }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let resolver = self.id.parent.resolver(db.upcast());
+        let environment = TraitEnvironment::lower(db, &resolver);
+        let ty = Ty::Placeholder(self.id);
+        Type {
+            krate: self.id.parent.module(db.upcast()).krate,
+            ty: InEnvironment { value: ty, environment },
+        }
+    }
 }
 
 // FIXME: rename from `ImplDef` to `Impl`
@@ -1157,18 +1167,21 @@ impl Type {
 
     pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
         if let Ty::Apply(a_ty) = &self.ty.value {
-            if let TypeCtor::Adt(AdtId::StructId(s)) = a_ty.ctor {
-                let var_def = s.into();
-                return db
-                    .field_types(var_def)
-                    .iter()
-                    .map(|(local_id, ty)| {
-                        let def = Field { parent: var_def.into(), id: local_id };
-                        let ty = ty.clone().subst(&a_ty.parameters);
-                        (def, self.derived(ty))
-                    })
-                    .collect();
-            }
+            let variant_id = match a_ty.ctor {
+                TypeCtor::Adt(AdtId::StructId(s)) => s.into(),
+                TypeCtor::Adt(AdtId::UnionId(u)) => u.into(),
+                _ => return Vec::new(),
+            };
+
+            return db
+                .field_types(variant_id)
+                .iter()
+                .map(|(local_id, ty)| {
+                    let def = Field { parent: variant_id.into(), id: local_id };
+                    let ty = ty.clone().subst(&a_ty.parameters);
+                    (def, self.derived(ty))
+                })
+                .collect();
         };
         Vec::new()
     }
diff --git a/crates/ra_hir/src/semantics.rs b/crates/ra_hir/src/semantics.rs
index 86bfb416c..a0a0f234b 100644
--- a/crates/ra_hir/src/semantics.rs
+++ b/crates/ra_hir/src/semantics.rs
@@ -9,6 +9,7 @@ use hir_def::{
     AsMacroCall, TraitId,
 };
 use hir_expand::ExpansionInfo;
+use hir_ty::associated_type_shorthand_candidates;
 use itertools::Itertools;
 use ra_db::{FileId, FileRange};
 use ra_prof::profile;
@@ -24,8 +25,9 @@ use crate::{
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
     AssocItem, Field, Function, HirFileId, ImplDef, InFile, Local, MacroDef, Module, ModuleDef,
-    Name, Origin, Path, ScopeDef, Trait, Type, TypeParam,
+    Name, Origin, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam,
 };
+use resolver::TypeNs;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum PathResolution {
@@ -40,6 +42,44 @@ pub enum PathResolution {
     AssocItem(AssocItem),
 }
 
+impl PathResolution {
+    fn in_type_ns(&self) -> Option<TypeNs> {
+        match self {
+            PathResolution::Def(ModuleDef::Adt(adt)) => Some(TypeNs::AdtId((*adt).into())),
+            PathResolution::Def(ModuleDef::BuiltinType(builtin)) => {
+                Some(TypeNs::BuiltinType(*builtin))
+            }
+            PathResolution::Def(ModuleDef::Const(_))
+            | PathResolution::Def(ModuleDef::EnumVariant(_))
+            | PathResolution::Def(ModuleDef::Function(_))
+            | PathResolution::Def(ModuleDef::Module(_))
+            | PathResolution::Def(ModuleDef::Static(_))
+            | PathResolution::Def(ModuleDef::Trait(_)) => None,
+            PathResolution::Def(ModuleDef::TypeAlias(alias)) => {
+                Some(TypeNs::TypeAliasId((*alias).into()))
+            }
+            PathResolution::Local(_) | PathResolution::Macro(_) => None,
+            PathResolution::TypeParam(param) => Some(TypeNs::GenericParam((*param).into())),
+            PathResolution::SelfType(impl_def) => Some(TypeNs::SelfType((*impl_def).into())),
+            PathResolution::AssocItem(AssocItem::Const(_))
+            | PathResolution::AssocItem(AssocItem::Function(_)) => None,
+            PathResolution::AssocItem(AssocItem::TypeAlias(alias)) => {
+                Some(TypeNs::TypeAliasId((*alias).into()))
+            }
+        }
+    }
+
+    /// Returns an iterator over associated types that may be specified after this path (using
+    /// `Ty::Assoc` syntax).
+    pub fn assoc_type_shorthand_candidates<R>(
+        &self,
+        db: &dyn HirDatabase,
+        mut cb: impl FnMut(TypeAlias) -> Option<R>,
+    ) -> Option<R> {
+        associated_type_shorthand_candidates(db, self.in_type_ns()?, |_, _, id| cb(id.into()))
+    }
+}
+
 /// Primary API to get semantic information, like types, from syntax trees.
 pub struct Semantics<'db, DB> {
     pub db: &'db DB,
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 571603854..f467ed3fe 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -182,10 +182,6 @@ impl ExprCollector<'_> {
 
                 self.alloc_expr(Expr::If { condition, then_branch, else_branch }, syntax_ptr)
             }
-            ast::Expr::TryBlockExpr(e) => {
-                let body = self.collect_block_opt(e.body());
-                self.alloc_expr(Expr::TryBlock { body }, syntax_ptr)
-            }
             ast::Expr::BlockExpr(e) => self.collect_block(e),
             ast::Expr::LoopExpr(e) => {
                 let body = self.collect_block_opt(e.loop_body());
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index a0cdad529..aad12e123 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -101,9 +101,6 @@ pub enum Expr {
     Try {
         expr: ExprId,
     },
-    TryBlock {
-        body: ExprId,
-    },
     Cast {
         expr: ExprId,
         type_ref: TypeRef,
@@ -239,7 +236,6 @@ impl Expr {
                     f(*expr);
                 }
             }
-            Expr::TryBlock { body } => f(*body),
             Expr::Loop { body } => f(*body),
             Expr::While { condition, body } => {
                 f(*condition);
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 83f946eee..efc60986b 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -73,11 +73,6 @@ impl<'a> InferenceContext<'a> {
                 self.coerce_merge_branch(&then_ty, &else_ty)
             }
             Expr::Block { statements, tail } => self.infer_block(statements, *tail, expected),
-            Expr::TryBlock { body } => {
-                let _inner = self.infer_expr(*body, expected);
-                // FIXME should be std::result::Result<{inner}, _>
-                Ty::Unknown
-            }
             Expr::Loop { body } => {
                 self.infer_expr(*body, &Expectation::has_type(Ty::unit()));
                 // FIXME handle break with value
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index a8ef32ec5..a6f56c661 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -66,7 +66,8 @@ pub use autoderef::autoderef;
 pub use infer::{InferTy, InferenceResult};
 pub use lower::CallableDef;
 pub use lower::{
-    callable_item_sig, ImplTraitLoweringMode, TyDefId, TyLoweringContext, ValueTyDefId,
+    associated_type_shorthand_candidates, callable_item_sig, ImplTraitLoweringMode, TyDefId,
+    TyLoweringContext, ValueTyDefId,
 };
 pub use traits::{InEnvironment, Obligation, ProjectionPredicate, TraitEnvironment};
 
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index a6f893037..9ad6dbe07 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -17,9 +17,9 @@ use hir_def::{
     path::{GenericArg, Path, PathSegment, PathSegments},
     resolver::{HasResolver, Resolver, TypeNs},
     type_ref::{TypeBound, TypeRef},
-    AdtId, AssocContainerId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule,
-    ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
-    VariantId,
+    AdtId, AssocContainerId, AssocItemId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId,
+    HasModule, ImplId, LocalFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
+    UnionId, VariantId,
 };
 use ra_arena::map::ArenaMap;
 use ra_db::CrateId;
@@ -34,6 +34,7 @@ use crate::{
     Binders, BoundVar, DebruijnIndex, FnSig, GenericPredicate, PolyFnSig, ProjectionPredicate,
     ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk,
 };
+use hir_expand::name::Name;
 
 #[derive(Debug)]
 pub struct TyLoweringContext<'a> {
@@ -383,61 +384,38 @@ impl Ty {
         res: Option<TypeNs>,
         segment: PathSegment<'_>,
     ) -> Ty {
-        let traits_from_env: Vec<_> = match res {
-            Some(TypeNs::SelfType(impl_id)) => match ctx.db.impl_trait(impl_id) {
-                None => return Ty::Unknown,
-                Some(trait_ref) => vec![trait_ref.value],
-            },
-            Some(TypeNs::GenericParam(param_id)) => {
-                let predicates = ctx.db.generic_predicates_for_param(param_id);
-                let mut traits_: Vec<_> = predicates
-                    .iter()
-                    .filter_map(|pred| match &pred.value {
-                        GenericPredicate::Implemented(tr) => Some(tr.clone()),
-                        _ => None,
-                    })
-                    .collect();
-                // Handle `Self::Type` referring to own associated type in trait definitions
-                if let GenericDefId::TraitId(trait_id) = param_id.parent {
-                    let generics = generics(ctx.db.upcast(), trait_id.into());
-                    if generics.params.types[param_id.local_id].provenance
-                        == TypeParamProvenance::TraitSelf
-                    {
-                        let trait_ref = TraitRef {
-                            trait_: trait_id,
-                            substs: Substs::bound_vars(&generics, DebruijnIndex::INNERMOST),
+        if let Some(res) = res {
+            let ty =
+                associated_type_shorthand_candidates(ctx.db, res, move |name, t, associated_ty| {
+                    if name == segment.name {
+                        let substs = match ctx.type_param_mode {
+                            TypeParamLoweringMode::Placeholder => {
+                                // if we're lowering to placeholders, we have to put
+                                // them in now
+                                let s = Substs::type_params(
+                                    ctx.db,
+                                    ctx.resolver.generic_def().expect(
+                                        "there should be generics if there's a generic param",
+                                    ),
+                                );
+                                t.substs.clone().subst_bound_vars(&s)
+                            }
+                            TypeParamLoweringMode::Variable => t.substs.clone(),
                         };
-                        traits_.push(trait_ref);
+                        // FIXME handle type parameters on the segment
+                        return Some(Ty::Projection(ProjectionTy {
+                            associated_ty,
+                            parameters: substs,
+                        }));
                     }
-                }
-                traits_
-            }
-            _ => return Ty::Unknown,
-        };
-        let traits = traits_from_env.into_iter().flat_map(|t| all_super_trait_refs(ctx.db, t));
-        for t in traits {
-            if let Some(associated_ty) =
-                ctx.db.trait_data(t.trait_).associated_type_by_name(&segment.name)
-            {
-                let substs = match ctx.type_param_mode {
-                    TypeParamLoweringMode::Placeholder => {
-                        // if we're lowering to placeholders, we have to put
-                        // them in now
-                        let s = Substs::type_params(
-                            ctx.db,
-                            ctx.resolver
-                                .generic_def()
-                                .expect("there should be generics if there's a generic param"),
-                        );
-                        t.substs.subst_bound_vars(&s)
-                    }
-                    TypeParamLoweringMode::Variable => t.substs,
-                };
-                // FIXME handle (forbid) type parameters on the segment
-                return Ty::Projection(ProjectionTy { associated_ty, parameters: substs });
-            }
+
+                    None
+                });
+
+            ty.unwrap_or(Ty::Unknown)
+        } else {
+            Ty::Unknown
         }
-        Ty::Unknown
     }
 
     fn from_hir_path_inner(
@@ -694,6 +672,61 @@ pub fn callable_item_sig(db: &dyn HirDatabase, def: CallableDef) -> PolyFnSig {
     }
 }
 
+pub fn associated_type_shorthand_candidates<R>(
+    db: &dyn HirDatabase,
+    res: TypeNs,
+    mut cb: impl FnMut(&Name, &TraitRef, TypeAliasId) -> Option<R>,
+) -> Option<R> {
+    let traits_from_env: Vec<_> = match res {
+        TypeNs::SelfType(impl_id) => match db.impl_trait(impl_id) {
+            None => vec![],
+            Some(trait_ref) => vec![trait_ref.value],
+        },
+        TypeNs::GenericParam(param_id) => {
+            let predicates = db.generic_predicates_for_param(param_id);
+            let mut traits_: Vec<_> = predicates
+                .iter()
+                .filter_map(|pred| match &pred.value {
+                    GenericPredicate::Implemented(tr) => Some(tr.clone()),
+                    _ => None,
+                })
+                .collect();
+            // Handle `Self::Type` referring to own associated type in trait definitions
+            if let GenericDefId::TraitId(trait_id) = param_id.parent {
+                let generics = generics(db.upcast(), trait_id.into());
+                if generics.params.types[param_id.local_id].provenance
+                    == TypeParamProvenance::TraitSelf
+                {
+                    let trait_ref = TraitRef {
+                        trait_: trait_id,
+                        substs: Substs::bound_vars(&generics, DebruijnIndex::INNERMOST),
+                    };
+                    traits_.push(trait_ref);
+                }
+            }
+            traits_
+        }
+        _ => vec![],
+    };
+
+    for t in traits_from_env.into_iter().flat_map(move |t| all_super_trait_refs(db, t)) {
+        let data = db.trait_data(t.trait_);
+
+        for (name, assoc_id) in &data.items {
+            match assoc_id {
+                AssocItemId::TypeAliasId(alias) => {
+                    if let Some(result) = cb(name, &t, *alias) {
+                        return Some(result);
+                    }
+                }
+                AssocItemId::FunctionId(_) | AssocItemId::ConstId(_) => {}
+            }
+        }
+    }
+
+    None
+}
+
 /// Build the type of all specific fields of a struct or enum variant.
 pub(crate) fn field_types_query(
     db: &dyn HirDatabase,
diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index 814354ffa..05f825c6f 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -250,6 +250,44 @@ mod tests {
     }
 
     #[test]
+    fn test_union_field_completion() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+            union Un {
+                field: u8,
+                other: u16,
+            }
+
+            fn foo(u: Un) {
+                u.<|>
+            }
+            ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "field",
+                source_range: 140..140,
+                delete: 140..140,
+                insert: "field",
+                kind: Field,
+                detail: "u8",
+            },
+            CompletionItem {
+                label: "other",
+                source_range: 140..140,
+                delete: 140..140,
+                insert: "other",
+                kind: Field,
+                detail: "u16",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn test_method_completion() {
         assert_debug_snapshot!(
         do_ref_completion(
diff --git a/crates/ra_ide/src/completion/complete_qualified_path.rs b/crates/ra_ide/src/completion/complete_qualified_path.rs
index dd10f74e6..aa56a5cd8 100644
--- a/crates/ra_ide/src/completion/complete_qualified_path.rs
+++ b/crates/ra_ide/src/completion/complete_qualified_path.rs
@@ -5,19 +5,29 @@ use ra_syntax::AstNode;
 use test_utils::tested_by;
 
 use crate::completion::{CompletionContext, Completions};
+use rustc_hash::FxHashSet;
 
 pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionContext) {
     let path = match &ctx.path_prefix {
         Some(path) => path.clone(),
         _ => return,
     };
-    let def = match ctx.scope().resolve_hir_path(&path) {
-        Some(PathResolution::Def(def)) => def,
-        _ => return,
+    let scope = ctx.scope();
+    let context_module = scope.module();
+
+    let res = match scope.resolve_hir_path(&path) {
+        Some(res) => res,
+        None => return,
     };
-    let context_module = ctx.scope().module();
-    match def {
-        hir::ModuleDef::Module(module) => {
+
+    // Add associated types on type parameters and `Self`.
+    res.assoc_type_shorthand_candidates(ctx.db, |alias| {
+        acc.add_type_alias(ctx, alias);
+        None::<()>
+    });
+
+    match res {
+        PathResolution::Def(hir::ModuleDef::Module(module)) => {
             let module_scope = module.scope(ctx.db, context_module);
             for (name, def) in module_scope {
                 if ctx.use_item_syntax.is_some() {
@@ -35,7 +45,8 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 acc.add_resolution(ctx, name.to_string(), &def);
             }
         }
-        hir::ModuleDef::Adt(_) | hir::ModuleDef::TypeAlias(_) => {
+        PathResolution::Def(def @ hir::ModuleDef::Adt(_))
+        | PathResolution::Def(def @ hir::ModuleDef::TypeAlias(_)) => {
             if let hir::ModuleDef::Adt(Adt::Enum(e)) = def {
                 for variant in e.variants(ctx.db) {
                     acc.add_enum_variant(ctx, variant, None);
@@ -46,8 +57,10 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 hir::ModuleDef::TypeAlias(a) => a.ty(ctx.db),
                 _ => unreachable!(),
             };
-            // Iterate assoc types separately
-            // FIXME: complete T::AssocType
+
+            // XXX: For parity with Rust bug #22519, this does not complete Ty::AssocType.
+            // (where AssocType is defined on a trait, not an inherent impl)
+
             let krate = ctx.krate;
             if let Some(krate) = krate {
                 let traits_in_scope = ctx.scope().traits_in_scope();
@@ -65,6 +78,7 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                     None::<()>
                 });
 
+                // Iterate assoc types separately
                 ty.iterate_impl_items(ctx.db, krate, |item| {
                     if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
                         return None;
@@ -77,7 +91,8 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 });
             }
         }
-        hir::ModuleDef::Trait(t) => {
+        PathResolution::Def(hir::ModuleDef::Trait(t)) => {
+            // Handles `Trait::assoc` as well as `<Ty as Trait>::assoc`.
             for item in t.items(ctx.db) {
                 if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
                     continue;
@@ -91,8 +106,38 @@ pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
                 }
             }
         }
+        PathResolution::TypeParam(_) | PathResolution::SelfType(_) => {
+            if let Some(krate) = ctx.krate {
+                let ty = match res {
+                    PathResolution::TypeParam(param) => param.ty(ctx.db),
+                    PathResolution::SelfType(impl_def) => impl_def.target_ty(ctx.db),
+                    _ => return,
+                };
+
+                let traits_in_scope = ctx.scope().traits_in_scope();
+                let mut seen = FxHashSet::default();
+                ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
+                    if context_module.map_or(false, |m| !item.is_visible_from(ctx.db, m)) {
+                        return None;
+                    }
+
+                    // We might iterate candidates of a trait multiple times here, so deduplicate
+                    // them.
+                    if seen.insert(item) {
+                        match item {
+                            hir::AssocItem::Function(func) => {
+                                acc.add_function(ctx, func, None);
+                            }
+                            hir::AssocItem::Const(ct) => acc.add_const(ctx, ct),
+                            hir::AssocItem::TypeAlias(ty) => acc.add_type_alias(ctx, ty),
+                        }
+                    }
+                    None::<()>
+                });
+            }
+        }
         _ => {}
-    };
+    }
 }
 
 #[cfg(test)]
@@ -844,6 +889,211 @@ mod tests {
     }
 
     #[test]
+    fn completes_ty_param_assoc_ty() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                trait Super {
+                    type Ty;
+                    const CONST: u8;
+                    fn func() {}
+                    fn method(&self) {}
+                }
+
+                trait Sub: Super {
+                    type SubTy;
+                    const C2: ();
+                    fn subfunc() {}
+                    fn submethod(&self) {}
+                }
+
+                fn foo<T: Sub>() {
+                    T::<|>
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "C2",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "C2",
+                kind: Const,
+                detail: "const C2: ();",
+            },
+            CompletionItem {
+                label: "CONST",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "CONST",
+                kind: Const,
+                detail: "const CONST: u8;",
+            },
+            CompletionItem {
+                label: "SubTy",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "SubTy",
+                kind: TypeAlias,
+                detail: "type SubTy;",
+            },
+            CompletionItem {
+                label: "Ty",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "Ty",
+                kind: TypeAlias,
+                detail: "type Ty;",
+            },
+            CompletionItem {
+                label: "func()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "func()$0",
+                kind: Function,
+                lookup: "func",
+                detail: "fn func()",
+            },
+            CompletionItem {
+                label: "method()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "method()$0",
+                kind: Method,
+                lookup: "method",
+                detail: "fn method(&self)",
+            },
+            CompletionItem {
+                label: "subfunc()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "subfunc()$0",
+                kind: Function,
+                lookup: "subfunc",
+                detail: "fn subfunc()",
+            },
+            CompletionItem {
+                label: "submethod()",
+                source_range: 219..219,
+                delete: 219..219,
+                insert: "submethod()$0",
+                kind: Method,
+                lookup: "submethod",
+                detail: "fn submethod(&self)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn completes_self_param_assoc_ty() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                trait Super {
+                    type Ty;
+                    const CONST: u8 = 0;
+                    fn func() {}
+                    fn method(&self) {}
+                }
+
+                trait Sub: Super {
+                    type SubTy;
+                    const C2: () = ();
+                    fn subfunc() {}
+                    fn submethod(&self) {}
+                }
+
+                struct Wrap<T>(T);
+                impl<T> Super for Wrap<T> {}
+                impl<T> Sub for Wrap<T> {
+                    fn subfunc() {
+                        // Should be able to assume `Self: Sub + Super`
+                        Self::<|>
+                    }
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "C2",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "C2",
+                kind: Const,
+                detail: "const C2: () = ();",
+            },
+            CompletionItem {
+                label: "CONST",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "CONST",
+                kind: Const,
+                detail: "const CONST: u8 = 0;",
+            },
+            CompletionItem {
+                label: "SubTy",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "SubTy",
+                kind: TypeAlias,
+                detail: "type SubTy;",
+            },
+            CompletionItem {
+                label: "Ty",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "Ty",
+                kind: TypeAlias,
+                detail: "type Ty;",
+            },
+            CompletionItem {
+                label: "func()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "func()$0",
+                kind: Function,
+                lookup: "func",
+                detail: "fn func()",
+            },
+            CompletionItem {
+                label: "method()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "method()$0",
+                kind: Method,
+                lookup: "method",
+                detail: "fn method(&self)",
+            },
+            CompletionItem {
+                label: "subfunc()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "subfunc()$0",
+                kind: Function,
+                lookup: "subfunc",
+                detail: "fn subfunc()",
+            },
+            CompletionItem {
+                label: "submethod()",
+                source_range: 365..365,
+                delete: 365..365,
+                insert: "submethod()$0",
+                kind: Method,
+                lookup: "submethod",
+                detail: "fn submethod(&self)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
     fn completes_type_alias() {
         assert_debug_snapshot!(
             do_reference_completion(
diff --git a/crates/ra_ide/src/completion/complete_unqualified_path.rs b/crates/ra_ide/src/completion/complete_unqualified_path.rs
index f559f2b97..a6a5568de 100644
--- a/crates/ra_ide/src/completion/complete_unqualified_path.rs
+++ b/crates/ra_ide/src/completion/complete_unqualified_path.rs
@@ -53,7 +53,7 @@ fn complete_enum_variants(acc: &mut Completions, ctx: &CompletionContext, ty: &T
                 // Variants with trivial paths are already added by the existing completion logic,
                 // so we should avoid adding these twice
                 if path.segments.len() > 1 {
-                    acc.add_enum_variant(ctx, variant, Some(path.to_string()));
+                    acc.add_qualified_enum_variant(ctx, variant, path);
                 }
             }
         }
@@ -1173,6 +1173,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1181,6 +1182,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1189,6 +1191,7 @@ mod tests {
                 delete: 248..250,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
         ]
@@ -1231,6 +1234,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1239,6 +1243,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1247,6 +1252,7 @@ mod tests {
                 delete: 219..221,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
         ]
@@ -1285,6 +1291,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Bar",
                 kind: EnumVariant,
+                lookup: "Bar",
                 detail: "()",
             },
             CompletionItem {
@@ -1293,6 +1300,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Baz",
                 kind: EnumVariant,
+                lookup: "Baz",
                 detail: "()",
             },
             CompletionItem {
@@ -1301,6 +1309,7 @@ mod tests {
                 delete: 185..186,
                 insert: "Foo::Quux",
                 kind: EnumVariant,
+                lookup: "Quux",
                 detail: "()",
             },
             CompletionItem {
@@ -1353,6 +1362,7 @@ mod tests {
                 delete: 98..99,
                 insert: "m::E::V",
                 kind: EnumVariant,
+                lookup: "V",
                 detail: "()",
             },
         ]
diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index 77d354376..2edb130cf 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -1,6 +1,6 @@
 //! This modules takes care of rendering various definitions as completion items.
 
-use hir::{Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, StructKind, Type};
+use hir::{Docs, HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
 use ra_syntax::ast::NameOwner;
 use stdx::SepBy;
 use test_utils::tested_by;
@@ -246,14 +246,37 @@ impl Completions {
             .add_to(self);
     }
 
+    pub(crate) fn add_qualified_enum_variant(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        path: ModPath,
+    ) {
+        self.add_enum_variant_impl(ctx, variant, None, Some(path))
+    }
+
     pub(crate) fn add_enum_variant(
         &mut self,
         ctx: &CompletionContext,
         variant: hir::EnumVariant,
         local_name: Option<String>,
     ) {
+        self.add_enum_variant_impl(ctx, variant, local_name, None)
+    }
+
+    fn add_enum_variant_impl(
+        &mut self,
+        ctx: &CompletionContext,
+        variant: hir::EnumVariant,
+        local_name: Option<String>,
+        path: Option<ModPath>,
+    ) {
         let is_deprecated = is_deprecated(variant, ctx.db);
         let name = local_name.unwrap_or_else(|| variant.name(ctx.db).to_string());
+        let qualified_name = match &path {
+            Some(it) => it.to_string(),
+            None => name.to_string(),
+        };
         let detail_types = variant
             .fields(ctx.db)
             .into_iter()
@@ -271,16 +294,23 @@ impl Completions {
                 .surround_with("{ ", " }")
                 .to_string(),
         };
-        let mut res =
-            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.clone())
-                .kind(CompletionItemKind::EnumVariant)
-                .set_documentation(variant.docs(ctx.db))
-                .set_deprecated(is_deprecated)
-                .detail(detail);
+        let mut res = CompletionItem::new(
+            CompletionKind::Reference,
+            ctx.source_range(),
+            qualified_name.clone(),
+        )
+        .kind(CompletionItemKind::EnumVariant)
+        .set_documentation(variant.docs(ctx.db))
+        .set_deprecated(is_deprecated)
+        .detail(detail);
+
+        if path.is_some() {
+            res = res.lookup_by(name);
+        }
 
         if variant_kind == StructKind::Tuple {
             let params = Params::Anonymous(variant.fields(ctx.db).len());
-            res = res.add_call_parens(ctx, name, params)
+            res = res.add_call_parens(ctx, qualified_name, params)
         }
 
         res.add_to(self);
diff --git a/crates/ra_ide/src/display/function_signature.rs b/crates/ra_ide/src/display/function_signature.rs
index b5e2785fe..db3907fe6 100644
--- a/crates/ra_ide/src/display/function_signature.rs
+++ b/crates/ra_ide/src/display/function_signature.rs
@@ -26,6 +26,8 @@ pub struct FunctionSignature {
     pub kind: CallableKind,
     /// Optional visibility
     pub visibility: Option<String>,
+    /// Qualifiers like `async`, `unsafe`, ...
+    pub qualifier: FunctionQualifier,
     /// Name of the function
     pub name: Option<String>,
     /// Documentation for the function
@@ -46,6 +48,16 @@ pub struct FunctionSignature {
     pub has_self_param: bool,
 }
 
+#[derive(Debug, Default)]
+pub struct FunctionQualifier {
+    // `async` and `const` are mutually exclusive. Do we need to enforcing it here?
+    pub is_async: bool,
+    pub is_const: bool,
+    pub is_unsafe: bool,
+    /// The string `extern ".."`
+    pub extern_abi: Option<String>,
+}
+
 impl FunctionSignature {
     pub(crate) fn with_doc_opt(mut self, doc: Option<Documentation>) -> Self {
         self.doc = doc;
@@ -83,6 +95,8 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::StructConstructor,
                 visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+                // Do we need `const`?
+                qualifier: Default::default(),
                 name: node.name().map(|n| n.text().to_string()),
                 ret_type: node.name().map(|n| n.text().to_string()),
                 parameters: params,
@@ -128,6 +142,8 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::VariantConstructor,
                 visibility: None,
+                // Do we need `const`?
+                qualifier: Default::default(),
                 name: Some(name),
                 ret_type: None,
                 parameters: params,
@@ -151,6 +167,7 @@ impl FunctionSignature {
             FunctionSignature {
                 kind: CallableKind::Macro,
                 visibility: None,
+                qualifier: Default::default(),
                 name: node.name().map(|n| n.text().to_string()),
                 ret_type: None,
                 parameters: params,
@@ -223,6 +240,12 @@ impl From<&'_ ast::FnDef> for FunctionSignature {
         FunctionSignature {
             kind: CallableKind::Function,
             visibility: node.visibility().map(|n| n.syntax().text().to_string()),
+            qualifier: FunctionQualifier {
+                is_async: node.async_token().is_some(),
+                is_const: node.const_token().is_some(),
+                is_unsafe: node.unsafe_token().is_some(),
+                extern_abi: node.abi().map(|n| n.to_string()),
+            },
             name: node.name().map(|n| n.text().to_string()),
             ret_type: node
                 .ret_type()
@@ -246,6 +269,23 @@ impl Display for FunctionSignature {
             write!(f, "{} ", t)?;
         }
 
+        if self.qualifier.is_async {
+            write!(f, "async ")?;
+        }
+
+        if self.qualifier.is_const {
+            write!(f, "const ")?;
+        }
+
+        if self.qualifier.is_unsafe {
+            write!(f, "unsafe ")?;
+        }
+
+        if let Some(extern_abi) = &self.qualifier.extern_abi {
+            // Keyword `extern` is included in the string.
+            write!(f, "{} ", extern_abi)?;
+        }
+
         if let Some(name) = &self.name {
             match self.kind {
                 CallableKind::Function => write!(f, "fn {}", name)?,
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index 58c799eca..a62f598f0 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -844,4 +844,29 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["fn foo()\n```\n\n<- `\u{3000}` here"],
         );
     }
+
+    #[test]
+    fn test_hover_function_show_qualifiers() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            async fn foo<|>() {}
+            ",
+            &["async fn foo()"],
+        );
+        check_hover_result(
+            "
+            //- /lib.rs
+            pub const unsafe fn foo<|>() {}
+            ",
+            &["pub const unsafe fn foo()"],
+        );
+        check_hover_result(
+            r#"
+            //- /lib.rs
+            pub(crate) async unsafe extern "C" fn foo<|>() {}
+            "#,
+            &[r#"pub(crate) async unsafe extern "C" fn foo()"#],
+        );
+    }
 }
diff --git a/crates/ra_ide/src/join_lines.rs b/crates/ra_ide/src/join_lines.rs
index fde0bfa98..d0def7eaa 100644
--- a/crates/ra_ide/src/join_lines.rs
+++ b/crates/ra_ide/src/join_lines.rs
@@ -131,6 +131,9 @@ fn has_comma_after(node: &SyntaxNode) -> bool {
 fn join_single_expr_block(edit: &mut TextEditBuilder, token: &SyntaxToken) -> Option<()> {
     let block = ast::Block::cast(token.parent())?;
     let block_expr = ast::BlockExpr::cast(block.syntax().parent()?)?;
+    if !block_expr.is_standalone() {
+        return None;
+    }
     let expr = extract_trivial_expression(&block_expr)?;
 
     let block_range = block_expr.syntax().text_range();
@@ -662,4 +665,67 @@ fn main() {
         ",
         )
     }
+
+    #[test]
+    fn join_lines_mandatory_blocks_block() {
+        check_join_lines(
+            r"
+<|>fn foo() {
+    92
+}
+        ",
+            r"
+<|>fn foo() { 92
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>if true {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>if true { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>loop {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>loop { 92
+    }
+}
+        ",
+        );
+
+        check_join_lines(
+            r"
+fn foo() {
+    <|>unsafe {
+        92
+    }
+}
+        ",
+            r"
+fn foo() {
+    <|>unsafe { 92
+    }
+}
+        ",
+        );
+    }
 }
diff --git a/crates/ra_parser/src/grammar/expressions/atom.rs b/crates/ra_parser/src/grammar/expressions/atom.rs
index 0d277a586..76aa601cb 100644
--- a/crates/ra_parser/src/grammar/expressions/atom.rs
+++ b/crates/ra_parser/src/grammar/expressions/atom.rs
@@ -84,7 +84,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
         T![box] => box_expr(p, None),
         T![for] => for_expr(p, None),
         T![while] => while_expr(p, None),
-        T![try] => try_block_expr(p, None),
+        T![try] => try_expr(p, None),
         LIFETIME if la == T![:] => {
             let m = p.start();
             label(p);
@@ -134,7 +134,7 @@ pub(super) fn atom_expr(p: &mut Parser, r: Restrictions) -> Option<(CompletedMar
         }
     };
     let blocklike = match done.kind() {
-        IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR | TRY_BLOCK_EXPR => {
+        IF_EXPR | WHILE_EXPR | FOR_EXPR | LOOP_EXPR | MATCH_EXPR | BLOCK_EXPR | TRY_EXPR => {
             BlockLike::Block
         }
         _ => BlockLike::NotBlock,
@@ -532,9 +532,25 @@ fn break_expr(p: &mut Parser, r: Restrictions) -> CompletedMarker {
 // fn foo() {
 //     let _ = try {};
 // }
-fn try_block_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
+fn try_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
     assert!(p.at(T![try]));
     let m = m.unwrap_or_else(|| p.start());
+    // Special-case `try!` as macro.
+    // This is a hack until we do proper edition support
+    if p.nth_at(1, T![!]) {
+        // test try_macro_fallback
+        // fn foo() { try!(Ok(())); }
+        let path = p.start();
+        let path_segment = p.start();
+        let name_ref = p.start();
+        p.bump_remap(IDENT);
+        name_ref.complete(p, NAME_REF);
+        path_segment.complete(p, PATH_SEGMENT);
+        path.complete(p, PATH);
+        let _block_like = items::macro_call_after_excl(p);
+        return m.complete(p, MACRO_CALL);
+    }
+
     p.bump(T![try]);
     block(p);
     m.complete(p, TRY_EXPR)
diff --git a/crates/ra_parser/src/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index 433ed6812..1503a8730 100644
--- a/crates/ra_parser/src/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
@@ -415,6 +415,17 @@ pub(super) fn macro_call_after_excl(p: &mut Parser) -> BlockLike {
     if p.at(IDENT) {
         name(p);
     }
+    // Special-case `macro_rules! try`.
+    // This is a hack until we do proper edition support
+
+    // test try_macro_rules
+    // macro_rules! try { () => {} }
+    if p.at(T![try]) {
+        let m = p.start();
+        p.bump_remap(IDENT);
+        m.complete(p, NAME);
+    }
+
     match p.current() {
         T!['{'] => {
             token_tree(p);
diff --git a/crates/ra_parser/src/grammar/items/use_item.rs b/crates/ra_parser/src/grammar/items/use_item.rs
index e3b991c8c..3a0c7a31a 100644
--- a/crates/ra_parser/src/grammar/items/use_item.rs
+++ b/crates/ra_parser/src/grammar/items/use_item.rs
@@ -47,7 +47,7 @@ fn use_tree(p: &mut Parser, top_level: bool) {
         // use {crate::path::from::root, or::path::from::crate_name}; // Rust 2018 (with a crate named `or`)
         // use {path::from::root}; // Rust 2015
         // use ::{some::arbritrary::path}; // Rust 2015
-        // use ::{{{crate::export}}}; // Nonsensical but perfectly legal nestnig
+        // use ::{{{root::export}}}; // Nonsensical but perfectly legal nesting
         T!['{'] => {
             use_tree_list(p);
         }
diff --git a/crates/ra_parser/src/syntax_kind/generated.rs b/crates/ra_parser/src/syntax_kind/generated.rs
index 524e7d784..ab727ed7e 100644
--- a/crates/ra_parser/src/syntax_kind/generated.rs
+++ b/crates/ra_parser/src/syntax_kind/generated.rs
@@ -191,7 +191,6 @@ pub enum SyntaxKind {
     RECORD_LIT,
     RECORD_FIELD_LIST,
     RECORD_FIELD,
-    TRY_BLOCK_EXPR,
     BOX_EXPR,
     CALL_EXPR,
     INDEX_EXPR,
diff --git a/crates/ra_proc_macro_srv/src/cli.rs b/crates/ra_proc_macro_srv/src/cli.rs
index 7282e5b9b..1437794c9 100644
--- a/crates/ra_proc_macro_srv/src/cli.rs
+++ b/crates/ra_proc_macro_srv/src/cli.rs
@@ -1,15 +1,17 @@
 //! Driver for proc macro server
 
-use crate::{expand_task, list_macros};
+use crate::ProcMacroSrv;
 use ra_proc_macro::msg::{self, Message};
 use std::io;
 
 pub fn run() -> io::Result<()> {
+    let mut srv = ProcMacroSrv::default();
+
     while let Some(req) = read_request()? {
         let res = match req {
-            msg::Request::ListMacro(task) => Ok(msg::Response::ListMacro(list_macros(&task))),
+            msg::Request::ListMacro(task) => srv.list_macros(&task).map(msg::Response::ListMacro),
             msg::Request::ExpansionMacro(task) => {
-                expand_task(&task).map(msg::Response::ExpansionMacro)
+                srv.expand(&task).map(msg::Response::ExpansionMacro)
             }
         };
 
diff --git a/crates/ra_proc_macro_srv/src/dylib.rs b/crates/ra_proc_macro_srv/src/dylib.rs
index d202eb0fd..aa84e951c 100644
--- a/crates/ra_proc_macro_srv/src/dylib.rs
+++ b/crates/ra_proc_macro_srv/src/dylib.rs
@@ -2,13 +2,12 @@
 
 use crate::{proc_macro::bridge, rustc_server::TokenStream};
 use std::fs::File;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use goblin::{mach::Mach, Object};
 use libloading::Library;
 use memmap::Mmap;
 use ra_proc_macro::ProcMacroKind;
-
 use std::io;
 
 const NEW_REGISTRAR_SYMBOL: &str = "_rustc_proc_macro_decls_";
@@ -109,23 +108,21 @@ impl ProcMacroLibraryLibloading {
     }
 }
 
-type ProcMacroLibraryImpl = ProcMacroLibraryLibloading;
-
 pub struct Expander {
-    libs: Vec<ProcMacroLibraryImpl>,
+    inner: ProcMacroLibraryLibloading,
 }
 
 impl Expander {
-    pub fn new(lib: &Path) -> Result<Expander, String> {
+    pub fn new(lib: &Path) -> io::Result<Expander> {
         // Some libraries for dynamic loading require canonicalized path even when it is
         // already absolute
-        let lib = lib
-            .canonicalize()
-            .unwrap_or_else(|err| panic!("Cannot canonicalize {}: {:?}", lib.display(), err));
+        let lib = lib.canonicalize()?;
+
+        let lib = ensure_file_with_lock_free_access(&lib)?;
 
-        let library = ProcMacroLibraryImpl::open(&lib).map_err(|e| e.to_string())?;
+        let library = ProcMacroLibraryLibloading::open(&lib)?;
 
-        Ok(Expander { libs: vec![library] })
+        Ok(Expander { inner: library })
     }
 
     pub fn expand(
@@ -141,38 +138,36 @@ impl Expander {
                 TokenStream::with_subtree(attr.clone())
             });
 
-        for lib in &self.libs {
-            for proc_macro in &lib.exported_macros {
-                match proc_macro {
-                    bridge::client::ProcMacro::CustomDerive { trait_name, client, .. }
-                        if *trait_name == macro_name =>
-                    {
-                        let res = client.run(
-                            &crate::proc_macro::bridge::server::SameThread,
-                            crate::rustc_server::Rustc::default(),
-                            parsed_body,
-                        );
-                        return res.map(|it| it.subtree);
-                    }
-                    bridge::client::ProcMacro::Bang { name, client } if *name == macro_name => {
-                        let res = client.run(
-                            &crate::proc_macro::bridge::server::SameThread,
-                            crate::rustc_server::Rustc::default(),
-                            parsed_body,
-                        );
-                        return res.map(|it| it.subtree);
-                    }
-                    bridge::client::ProcMacro::Attr { name, client } if *name == macro_name => {
-                        let res = client.run(
-                            &crate::proc_macro::bridge::server::SameThread,
-                            crate::rustc_server::Rustc::default(),
-                            parsed_attributes,
-                            parsed_body,
-                        );
-                        return res.map(|it| it.subtree);
-                    }
-                    _ => continue,
+        for proc_macro in &self.inner.exported_macros {
+            match proc_macro {
+                bridge::client::ProcMacro::CustomDerive { trait_name, client, .. }
+                    if *trait_name == macro_name =>
+                {
+                    let res = client.run(
+                        &crate::proc_macro::bridge::server::SameThread,
+                        crate::rustc_server::Rustc::default(),
+                        parsed_body,
+                    );
+                    return res.map(|it| it.subtree);
+                }
+                bridge::client::ProcMacro::Bang { name, client } if *name == macro_name => {
+                    let res = client.run(
+                        &crate::proc_macro::bridge::server::SameThread,
+                        crate::rustc_server::Rustc::default(),
+                        parsed_body,
+                    );
+                    return res.map(|it| it.subtree);
+                }
+                bridge::client::ProcMacro::Attr { name, client } if *name == macro_name => {
+                    let res = client.run(
+                        &crate::proc_macro::bridge::server::SameThread,
+                        crate::rustc_server::Rustc::default(),
+                        parsed_attributes,
+                        parsed_body,
+                    );
+                    return res.map(|it| it.subtree);
                 }
+                _ => continue,
             }
         }
 
@@ -180,9 +175,9 @@ impl Expander {
     }
 
     pub fn list_macros(&self) -> Vec<(String, ProcMacroKind)> {
-        self.libs
+        self.inner
+            .exported_macros
             .iter()
-            .flat_map(|it| &it.exported_macros)
             .map(|proc_macro| match proc_macro {
                 bridge::client::ProcMacro::CustomDerive { trait_name, .. } => {
                     (trait_name.to_string(), ProcMacroKind::CustomDerive)
@@ -197,3 +192,33 @@ impl Expander {
             .collect()
     }
 }
+
+/// Copy the dylib to temp directory to prevent locking in Windows
+#[cfg(windows)]
+fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
+    use std::{ffi::OsString, time::SystemTime};
+
+    let mut to = std::env::temp_dir();
+
+    let file_name = path.file_name().ok_or_else(|| {
+        io::Error::new(
+            io::ErrorKind::InvalidInput,
+            format!("File path is invalid: {}", path.display()),
+        )
+    })?;
+
+    // generate a time deps unique number
+    let t = SystemTime::now().duration_since(std::time::UNIX_EPOCH).expect("Time went backwards");
+
+    let mut unique_name = OsString::from(t.as_millis().to_string());
+    unique_name.push(file_name);
+
+    to.push(unique_name);
+    std::fs::copy(path, &to).unwrap();
+    Ok(to)
+}
+
+#[cfg(unix)]
+fn ensure_file_with_lock_free_access(path: &Path) -> io::Result<PathBuf> {
+    Ok(path.to_path_buf())
+}
diff --git a/crates/ra_proc_macro_srv/src/lib.rs b/crates/ra_proc_macro_srv/src/lib.rs
index 3aca859db..922bb84bb 100644
--- a/crates/ra_proc_macro_srv/src/lib.rs
+++ b/crates/ra_proc_macro_srv/src/lib.rs
@@ -21,28 +21,46 @@ mod dylib;
 
 use proc_macro::bridge::client::TokenStream;
 use ra_proc_macro::{ExpansionResult, ExpansionTask, ListMacrosResult, ListMacrosTask};
-use std::path::Path;
+use std::{
+    collections::{hash_map::Entry, HashMap},
+    fs,
+    path::{Path, PathBuf},
+    time::SystemTime,
+};
 
-pub(crate) fn expand_task(task: &ExpansionTask) -> Result<ExpansionResult, String> {
-    let expander = create_expander(&task.lib);
+#[derive(Default)]
+pub(crate) struct ProcMacroSrv {
+    expanders: HashMap<(PathBuf, SystemTime), dylib::Expander>,
+}
 
-    match expander.expand(&task.macro_name, &task.macro_body, task.attributes.as_ref()) {
-        Ok(expansion) => Ok(ExpansionResult { expansion }),
-        Err(msg) => {
-            Err(format!("Cannot perform expansion for {}: error {:?}", &task.macro_name, msg))
+impl ProcMacroSrv {
+    pub fn expand(&mut self, task: &ExpansionTask) -> Result<ExpansionResult, String> {
+        let expander = self.expander(&task.lib)?;
+        match expander.expand(&task.macro_name, &task.macro_body, task.attributes.as_ref()) {
+            Ok(expansion) => Ok(ExpansionResult { expansion }),
+            Err(msg) => {
+                Err(format!("Cannot perform expansion for {}: error {:?}", &task.macro_name, msg))
+            }
         }
     }
-}
 
-pub(crate) fn list_macros(task: &ListMacrosTask) -> ListMacrosResult {
-    let expander = create_expander(&task.lib);
+    pub fn list_macros(&mut self, task: &ListMacrosTask) -> Result<ListMacrosResult, String> {
+        let expander = self.expander(&task.lib)?;
+        Ok(ListMacrosResult { macros: expander.list_macros() })
+    }
 
-    ListMacrosResult { macros: expander.list_macros() }
-}
+    fn expander(&mut self, path: &Path) -> Result<&dylib::Expander, String> {
+        let time = fs::metadata(path).and_then(|it| it.modified()).map_err(|err| {
+            format!("Failed to get file metadata for {}: {:?}", path.display(), err)
+        })?;
 
-fn create_expander(lib: &Path) -> dylib::Expander {
-    dylib::Expander::new(lib)
-        .unwrap_or_else(|err| panic!("Cannot create expander for {}: {:?}", lib.display(), err))
+        Ok(match self.expanders.entry((path.to_path_buf(), time)) {
+            Entry::Vacant(v) => v.insert(dylib::Expander::new(path).map_err(|err| {
+                format!("Cannot create expander for {}: {:?}", path.display(), err)
+            })?),
+            Entry::Occupied(e) => e.into_mut(),
+        })
+    }
 }
 
 pub mod cli;
diff --git a/crates/ra_proc_macro_srv/src/tests/utils.rs b/crates/ra_proc_macro_srv/src/tests/utils.rs
index 2139ec7a4..646a427c5 100644
--- a/crates/ra_proc_macro_srv/src/tests/utils.rs
+++ b/crates/ra_proc_macro_srv/src/tests/utils.rs
@@ -1,7 +1,7 @@
 //! utils used in proc-macro tests
 
 use crate::dylib;
-use crate::list_macros;
+use crate::ProcMacroSrv;
 pub use difference::Changeset as __Changeset;
 use ra_proc_macro::ListMacrosTask;
 use std::str::FromStr;
@@ -59,7 +59,7 @@ pub fn assert_expand(
 pub fn list(crate_name: &str, version: &str) -> Vec<String> {
     let path = fixtures::dylib_path(crate_name, version);
     let task = ListMacrosTask { lib: path };
-
-    let res = list_macros(&task);
+    let mut srv = ProcMacroSrv::default();
+    let res = srv.list_macros(&task).unwrap();
     res.macros.into_iter().map(|(name, kind)| format!("{} [{:?}]", name, kind)).collect()
 }
diff --git a/crates/ra_prof/src/hprof.rs b/crates/ra_prof/src/hprof.rs
index 2b8a90363..a3f5321fb 100644
--- a/crates/ra_prof/src/hprof.rs
+++ b/crates/ra_prof/src/hprof.rs
@@ -30,8 +30,9 @@ pub fn init_from(spec: &str) {
 pub type Label = &'static str;
 
 /// This function starts a profiling scope in the current execution stack with a given description.
-/// It returns a Profile structure and measure elapsed time between this method invocation and Profile structure drop.
-/// It supports nested profiling scopes in case when this function invoked multiple times at the execution stack. In this case the profiling information will be nested at the output.
+/// It returns a `Profile` struct that measures elapsed time between this method invocation and `Profile` struct drop.
+/// It supports nested profiling scopes in case when this function is invoked multiple times at the execution stack.
+/// In this case the profiling information will be nested at the output.
 /// Profiling information is being printed in the stderr.
 ///
 /// # Example
@@ -58,36 +59,35 @@ pub type Label = &'static str;
 /// ```
 pub fn profile(label: Label) -> Profiler {
     assert!(!label.is_empty());
-    let enabled = PROFILING_ENABLED.load(Ordering::Relaxed)
-        && PROFILE_STACK.with(|stack| stack.borrow_mut().push(label));
-    let label = if enabled { Some(label) } else { None };
-    Profiler { label, detail: None }
+
+    if PROFILING_ENABLED.load(Ordering::Relaxed)
+        && PROFILE_STACK.with(|stack| stack.borrow_mut().push(label))
+    {
+        Profiler(Some(ProfilerImpl { label, detail: None }))
+    } else {
+        Profiler(None)
+    }
 }
 
-pub struct Profiler {
-    label: Option<Label>,
+pub struct Profiler(Option<ProfilerImpl>);
+
+struct ProfilerImpl {
+    label: Label,
     detail: Option<String>,
 }
 
 impl Profiler {
     pub fn detail(mut self, detail: impl FnOnce() -> String) -> Profiler {
-        if self.label.is_some() {
-            self.detail = Some(detail())
+        if let Some(profiler) = &mut self.0 {
+            profiler.detail = Some(detail())
         }
         self
     }
 }
 
-impl Drop for Profiler {
+impl Drop for ProfilerImpl {
     fn drop(&mut self) {
-        match self {
-            Profiler { label: Some(label), detail } => {
-                PROFILE_STACK.with(|stack| {
-                    stack.borrow_mut().pop(label, detail.take());
-                });
-            }
-            Profiler { label: None, .. } => (),
-        }
+        PROFILE_STACK.with(|it| it.borrow_mut().pop(self.label, self.detail.take()));
     }
 }
 
@@ -179,21 +179,18 @@ impl ProfileStack {
     pub fn pop(&mut self, label: Label, detail: Option<String>) {
         let start = self.starts.pop().unwrap();
         let duration = start.elapsed();
-        let level = self.starts.len();
         self.messages.finish(Message { duration, label, detail });
-        if level == 0 {
+        if self.starts.is_empty() {
             let longer_than = self.filter.longer_than;
             // Convert to millis for comparison to avoid problems with rounding
             // (otherwise we could print `0ms` despite user's `>0` filter when
             // `duration` is just a few nanos).
             if duration.as_millis() > longer_than.as_millis() {
-                let stderr = stderr();
                 if let Some(root) = self.messages.root() {
-                    print(&self.messages, root, 0, longer_than, &mut stderr.lock());
+                    print(&self.messages, root, 0, longer_than, &mut stderr().lock());
                 }
             }
             self.messages.clear();
-            assert!(self.starts.is_empty())
         }
     }
 }
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 7fca5661e..521ca8ab8 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -16,7 +16,9 @@ use crate::{
 };
 
 pub use self::{
-    expr_extensions::{ArrayExprKind, BinOp, ElseBranch, LiteralKind, PrefixOp, RangeOp},
+    expr_extensions::{
+        ArrayExprKind, BinOp, BlockModifier, ElseBranch, LiteralKind, PrefixOp, RangeOp,
+    },
     extensions::{
         AttrKind, FieldKind, NameOrNameRef, PathSegmentKind, SelfParamKind, SlicePatComponents,
         StructKind, TypeBoundKind, VisibilityKind,
@@ -243,6 +245,21 @@ fn test_comments_preserve_trailing_whitespace() {
 }
 
 #[test]
+fn test_four_slash_line_comment() {
+    let file = SourceFile::parse(
+        r#"
+        //// too many slashes to be a doc comment
+        /// doc comment
+        mod foo {}
+        "#,
+    )
+    .ok()
+    .unwrap();
+    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
+    assert_eq!("doc comment", module.doc_comment_text().unwrap());
+}
+
+#[test]
 fn test_where_predicates() {
     fn assert_bound(text: &str, bound: Option<TypeBound>) {
         assert_eq!(text, bound.unwrap().syntax().text().to_string());
diff --git a/crates/ra_syntax/src/ast/expr_extensions.rs b/crates/ra_syntax/src/ast/expr_extensions.rs
index 1c1134bc5..329c80749 100644
--- a/crates/ra_syntax/src/ast/expr_extensions.rs
+++ b/crates/ra_syntax/src/ast/expr_extensions.rs
@@ -16,7 +16,7 @@ impl ast::Expr {
             | ast::Expr::WhileExpr(_)
             | ast::Expr::BlockExpr(_)
             | ast::Expr::MatchExpr(_)
-            | ast::Expr::TryBlockExpr(_) => true,
+            | ast::Expr::TryExpr(_) => true,
             _ => false,
         }
     }
@@ -359,7 +359,22 @@ impl ast::Literal {
     }
 }
 
+pub enum BlockModifier {
+    Async(SyntaxToken),
+    Unsafe(SyntaxToken),
+}
+
 impl ast::BlockExpr {
+    pub fn modifier(&self) -> Option<BlockModifier> {
+        if let Some(token) = self.async_token() {
+            return Some(BlockModifier::Async(token));
+        }
+        if let Some(token) = self.unsafe_token() {
+            return Some(BlockModifier::Unsafe(token));
+        }
+        None
+    }
+
     /// false if the block is an intrinsic part of the syntax and can't be
     /// replaced with arbitrary expression.
     ///
@@ -368,12 +383,15 @@ impl ast::BlockExpr {
     /// const FOO: () = { stand_alone };
     /// ```
     pub fn is_standalone(&self) -> bool {
-        let kind = match self.syntax().parent() {
+        if self.modifier().is_some() {
+            return false;
+        }
+        let parent = match self.syntax().parent() {
+            Some(it) => it,
             None => return true,
-            Some(it) => it.kind(),
         };
-        match kind {
-            FN_DEF | MATCH_ARM | IF_EXPR | WHILE_EXPR | LOOP_EXPR | TRY_BLOCK_EXPR => false,
+        match parent.kind() {
+            FN_DEF | IF_EXPR | WHILE_EXPR | LOOP_EXPR => false,
             _ => true,
         }
     }
diff --git a/crates/ra_syntax/src/ast/generated/nodes.rs b/crates/ra_syntax/src/ast/generated/nodes.rs
index 2cb3ad011..81260680f 100644
--- a/crates/ra_syntax/src/ast/generated/nodes.rs
+++ b/crates/ra_syntax/src/ast/generated/nodes.rs
@@ -476,16 +476,6 @@ impl LoopExpr {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct TryBlockExpr {
-    pub(crate) syntax: SyntaxNode,
-}
-impl ast::AttrsOwner for TryBlockExpr {}
-impl TryBlockExpr {
-    pub fn try_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![try]) }
-    pub fn body(&self) -> Option<BlockExpr> { support::child(&self.syntax) }
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct ForExpr {
     pub(crate) syntax: SyntaxNode,
 }
@@ -554,6 +544,7 @@ impl ast::AttrsOwner for BlockExpr {}
 impl BlockExpr {
     pub fn label(&self) -> Option<Label> { support::child(&self.syntax) }
     pub fn unsafe_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![unsafe]) }
+    pub fn async_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![async]) }
     pub fn block(&self) -> Option<Block> { support::child(&self.syntax) }
 }
 
@@ -1249,6 +1240,7 @@ pub struct PathSegment {
 }
 impl PathSegment {
     pub fn coloncolon_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![::]) }
+    pub fn crate_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![crate]) }
     pub fn l_angle_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![<]) }
     pub fn name_ref(&self) -> Option<NameRef> { support::child(&self.syntax) }
     pub fn type_arg_list(&self) -> Option<TypeArgList> { support::child(&self.syntax) }
@@ -1473,7 +1465,6 @@ pub enum Expr {
     FieldExpr(FieldExpr),
     AwaitExpr(AwaitExpr),
     TryExpr(TryExpr),
-    TryBlockExpr(TryBlockExpr),
     CastExpr(CastExpr),
     RefExpr(RefExpr),
     PrefixExpr(PrefixExpr),
@@ -1956,17 +1947,6 @@ impl AstNode for LoopExpr {
     }
     fn syntax(&self) -> &SyntaxNode { &self.syntax }
 }
-impl AstNode for TryBlockExpr {
-    fn can_cast(kind: SyntaxKind) -> bool { kind == TRY_BLOCK_EXPR }
-    fn cast(syntax: SyntaxNode) -> Option<Self> {
-        if Self::can_cast(syntax.kind()) {
-            Some(Self { syntax })
-        } else {
-            None
-        }
-    }
-    fn syntax(&self) -> &SyntaxNode { &self.syntax }
-}
 impl AstNode for ForExpr {
     fn can_cast(kind: SyntaxKind) -> bool { kind == FOR_EXPR }
     fn cast(syntax: SyntaxNode) -> Option<Self> {
@@ -3308,9 +3288,6 @@ impl From<AwaitExpr> for Expr {
 impl From<TryExpr> for Expr {
     fn from(node: TryExpr) -> Expr { Expr::TryExpr(node) }
 }
-impl From<TryBlockExpr> for Expr {
-    fn from(node: TryBlockExpr) -> Expr { Expr::TryBlockExpr(node) }
-}
 impl From<CastExpr> for Expr {
     fn from(node: CastExpr) -> Expr { Expr::CastExpr(node) }
 }
@@ -3341,9 +3318,8 @@ impl AstNode for Expr {
             TUPLE_EXPR | ARRAY_EXPR | PAREN_EXPR | PATH_EXPR | LAMBDA_EXPR | IF_EXPR
             | LOOP_EXPR | FOR_EXPR | WHILE_EXPR | CONTINUE_EXPR | BREAK_EXPR | LABEL
             | BLOCK_EXPR | RETURN_EXPR | MATCH_EXPR | RECORD_LIT | CALL_EXPR | INDEX_EXPR
-            | METHOD_CALL_EXPR | FIELD_EXPR | AWAIT_EXPR | TRY_EXPR | TRY_BLOCK_EXPR
-            | CAST_EXPR | REF_EXPR | PREFIX_EXPR | RANGE_EXPR | BIN_EXPR | LITERAL | MACRO_CALL
-            | BOX_EXPR => true,
+            | METHOD_CALL_EXPR | FIELD_EXPR | AWAIT_EXPR | TRY_EXPR | CAST_EXPR | REF_EXPR
+            | PREFIX_EXPR | RANGE_EXPR | BIN_EXPR | LITERAL | MACRO_CALL | BOX_EXPR => true,
             _ => false,
         }
     }
@@ -3371,7 +3347,6 @@ impl AstNode for Expr {
             FIELD_EXPR => Expr::FieldExpr(FieldExpr { syntax }),
             AWAIT_EXPR => Expr::AwaitExpr(AwaitExpr { syntax }),
             TRY_EXPR => Expr::TryExpr(TryExpr { syntax }),
-            TRY_BLOCK_EXPR => Expr::TryBlockExpr(TryBlockExpr { syntax }),
             CAST_EXPR => Expr::CastExpr(CastExpr { syntax }),
             REF_EXPR => Expr::RefExpr(RefExpr { syntax }),
             PREFIX_EXPR => Expr::PrefixExpr(PrefixExpr { syntax }),
@@ -3408,7 +3383,6 @@ impl AstNode for Expr {
             Expr::FieldExpr(it) => &it.syntax,
             Expr::AwaitExpr(it) => &it.syntax,
             Expr::TryExpr(it) => &it.syntax,
-            Expr::TryBlockExpr(it) => &it.syntax,
             Expr::CastExpr(it) => &it.syntax,
             Expr::RefExpr(it) => &it.syntax,
             Expr::PrefixExpr(it) => &it.syntax,
@@ -3889,11 +3863,6 @@ impl std::fmt::Display for LoopExpr {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
-impl std::fmt::Display for TryBlockExpr {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        std::fmt::Display::fmt(self.syntax(), f)
-    }
-}
 impl std::fmt::Display for ForExpr {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index ee0f5cc40..492088353 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -22,8 +22,7 @@ pub fn path_unqualified(segment: ast::PathSegment) -> ast::Path {
 pub fn path_qualified(qual: ast::Path, segment: ast::PathSegment) -> ast::Path {
     path_from_text(&format!("{}::{}", qual, segment))
 }
-
-pub fn path_from_text(text: &str) -> ast::Path {
+fn path_from_text(text: &str) -> ast::Path {
     ast_from_text(text)
 }
 
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
index 3865729b8..74906d8a6 100644
--- a/crates/ra_syntax/src/ast/tokens.rs
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -13,7 +13,12 @@ impl Comment {
     }
 
     pub fn prefix(&self) -> &'static str {
-        prefix_by_kind(self.kind())
+        for (prefix, k) in COMMENT_PREFIX_TO_KIND.iter() {
+            if *k == self.kind() && self.text().starts_with(prefix) {
+                return prefix;
+            }
+        }
+        unreachable!()
     }
 }
 
@@ -48,6 +53,7 @@ pub enum CommentPlacement {
 const COMMENT_PREFIX_TO_KIND: &[(&str, CommentKind)] = {
     use {CommentPlacement::*, CommentShape::*};
     &[
+        ("////", CommentKind { shape: Line, doc: None }),
         ("///", CommentKind { shape: Line, doc: Some(Outer) }),
         ("//!", CommentKind { shape: Line, doc: Some(Inner) }),
         ("/**", CommentKind { shape: Block, doc: Some(Outer) }),
@@ -69,15 +75,6 @@ fn kind_by_prefix(text: &str) -> CommentKind {
     panic!("bad comment text: {:?}", text)
 }
 
-fn prefix_by_kind(kind: CommentKind) -> &'static str {
-    for (prefix, k) in COMMENT_PREFIX_TO_KIND.iter() {
-        if *k == kind {
-            return prefix;
-        }
-    }
-    unreachable!()
-}
-
 impl Whitespace {
     pub fn spans_multiple_lines(&self) -> bool {
         let text = self.text();
diff --git a/crates/ra_syntax/src/validation.rs b/crates/ra_syntax/src/validation.rs
index 5e93895ec..f0b3dec63 100644
--- a/crates/ra_syntax/src/validation.rs
+++ b/crates/ra_syntax/src/validation.rs
@@ -96,6 +96,7 @@ pub(crate) fn validate(root: &SyntaxNode) -> Vec<SyntaxError> {
                 ast::RecordField(it) => validate_numeric_name(it.name_ref(), &mut errors),
                 ast::Visibility(it) => validate_visibility(it, &mut errors),
                 ast::RangeExpr(it) => validate_range_expr(it, &mut errors),
+                ast::PathSegment(it) => validate_crate_keyword_in_path_segment(it, &mut errors),
                 _ => (),
             }
         }
@@ -222,3 +223,60 @@ fn validate_range_expr(expr: ast::RangeExpr, errors: &mut Vec<SyntaxError>) {
         ));
     }
 }
+
+fn validate_crate_keyword_in_path_segment(
+    segment: ast::PathSegment,
+    errors: &mut Vec<SyntaxError>,
+) {
+    const ERR_MSG: &str = "The `crate` keyword is only allowed as the first segment of a path";
+
+    let crate_token = match segment.crate_token() {
+        None => return,
+        Some(it) => it,
+    };
+
+    // Disallow both ::crate and foo::crate
+    let mut path = segment.parent_path();
+    if segment.coloncolon_token().is_some() || path.qualifier().is_some() {
+        errors.push(SyntaxError::new(ERR_MSG, crate_token.text_range()));
+        return;
+    }
+
+    // For expressions and types, validation is complete, but we still have
+    // to handle invalid UseItems like this:
+    //
+    //      use foo:{crate::bar::baz};
+    //
+    // To handle this we must inspect the parent `UseItem`s and `UseTree`s
+    // but right now we're looking deep inside the nested `Path` nodes because
+    // `Path`s are left-associative:
+    //
+    //   ((crate)::bar)::baz)
+    //       ^ current value of path
+    //
+    // So we need to climb to the top
+    while let Some(parent) = path.parent_path() {
+        path = parent;
+    }
+
+    // Now that we've found the whole path we need to see if there's a prefix
+    // somewhere in the UseTree hierarchy. This check is arbitrarily deep
+    // because rust allows arbitrary nesting like so:
+    //
+    // use {foo::{{{{crate::bar::baz}}}}};
+    for node in path.syntax().ancestors().skip(1) {
+        match_ast! {
+            match node {
+                ast::UseTree(it) => if let Some(tree_path) = it.path() {
+                    // Even a top-level path exists within a `UseTree` so we must explicitly
+                    // allow our path but disallow anything else
+                    if tree_path != path {
+                        errors.push(SyntaxError::new(ERR_MSG, crate_token.text_range()));
+                    }
+                },
+                ast::UseTreeList(_it) => continue,
+                _ => return,
+            }
+        };
+    }
+}
diff --git a/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rast b/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rast
new file mode 100644
index 000000000..d2a549273
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rast
@@ -0,0 +1,91 @@
+[email protected]
+  [email protected]
+    [email protected] "use"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected] "::"
+          [email protected] "crate"
+    [email protected] ";"
+  [email protected] "\n"
+  [email protected]
+    [email protected] "use"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected] "{"
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "crate"
+        [email protected] ","
+        [email protected] " "
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "foo"
+          [email protected] "::"
+          [email protected]
+            [email protected] "{"
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected]
+                    [email protected]
+                      [email protected]
+                        [email protected] "crate"
+                    [email protected] "::"
+                    [email protected]
+                      [email protected]
+                        [email protected] "foo"
+                  [email protected] "::"
+                  [email protected]
+                    [email protected]
+                      [email protected] "bar"
+                [email protected] "::"
+                [email protected]
+                  [email protected]
+                    [email protected] "baz"
+            [email protected] "}"
+        [email protected] "}"
+    [email protected] ";"
+  [email protected] "\n"
+  [email protected]
+    [email protected] "use"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "hello"
+        [email protected] "::"
+        [email protected]
+          [email protected] "crate"
+    [email protected] ";"
+  [email protected] "\n"
+  [email protected]
+    [email protected] "use"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "hello"
+          [email protected] "::"
+          [email protected]
+            [email protected] "crate"
+        [email protected] "::"
+        [email protected]
+          [email protected]
+            [email protected] "there"
+    [email protected] ";"
+  [email protected] "\n"
+error 6..11: The `crate` keyword is only allowed as the first segment of a path
+error 31..36: The `crate` keyword is only allowed as the first segment of a path
+error 66..71: The `crate` keyword is only allowed as the first segment of a path
+error 84..89: The `crate` keyword is only allowed as the first segment of a path
diff --git a/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rs b/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rs
new file mode 100644
index 000000000..508def2c7
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0040_illegal_crate_kw_location.rs
@@ -0,0 +1,4 @@
+use ::crate;
+use {crate, foo::{crate::foo::bar::baz}};
+use hello::crate;
+use hello::crate::there;
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rast b/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rast
index bd74b44a6..cf3a90400 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rast
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rast
@@ -1,4 +1,4 @@
-[email protected]50
+[email protected]49
   [email protected]
     [email protected] "use"
     [email protected] " "
@@ -104,32 +104,33 @@ [email protected]
   [email protected] " "
   [email protected] "// Rust 2015"
   [email protected] "\n"
-  [email protected]6
+  [email protected]5
     [email protected] "use"
     [email protected] " "
-    [email protected]5
+    [email protected]4
       [email protected] "::"
-      [email protected]5
+      [email protected]4
         [email protected] "{"
-        [email protected]4
-          [email protected]4
+        [email protected]3
+          [email protected]3
             [email protected] "{"
-            [email protected]3
-              [email protected]3
+            [email protected]2
+              [email protected]2
                 [email protected] "{"
-                [email protected]
-                  [email protected]
-                    [email protected]
-                      [email protected]
-                        [email protected] "crate"
-                    [email protected] "::"
-                    [email protected]
-                      [email protected]
-                        [email protected] "export"
-                [email protected] "}"
-            [email protected] "}"
-        [email protected] "}"
-    [email protected] ";"
-  [email protected] " "
-  [email protected] "// Nonsensical but pe ..."
-  [email protected] "\n"
+                [email protected]
+                  [email protected]
+                    [email protected]
+                      [email protected]
+                        [email protected]
+                          [email protected] "root"
+                    [email protected] "::"
+                    [email protected]
+                      [email protected]
+                        [email protected] "export"
+                [email protected] "}"
+            [email protected] "}"
+        [email protected] "}"
+    [email protected] ";"
+  [email protected] " "
+  [email protected] "// Nonsensical but pe ..."
+  [email protected] "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rs b/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rs
index 06c387cee..381cba1e2 100644
--- a/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rs
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0002_use_tree_list.rs
@@ -1,4 +1,4 @@
 use {crate::path::from::root, or::path::from::crate_name}; // Rust 2018 (with a crate named `or`)
 use {path::from::root}; // Rust 2015
 use ::{some::arbritrary::path}; // Rust 2015
-use ::{{{crate::export}}}; // Nonsensical but perfectly legal nestnig
+use ::{{{root::export}}}; // Nonsensical but perfectly legal nesting
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rast b/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rast
new file mode 100644
index 000000000..beb6d8010
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rast
@@ -0,0 +1,35 @@
+[email protected]
+  [email protected]
+    [email protected] "fn"
+    [email protected] " "
+    [email protected]
+      [email protected] "foo"
+    [email protected]
+      [email protected] "("
+      [email protected] ")"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected] "{"
+        [email protected] " "
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected]
+                  [email protected] "try"
+            [email protected] "!"
+            [email protected]
+              [email protected] "("
+              [email protected] "Ok"
+              [email protected]
+                [email protected] "("
+                [email protected]
+                  [email protected] "("
+                  [email protected] ")"
+                [email protected] ")"
+              [email protected] ")"
+          [email protected] ";"
+        [email protected] " "
+        [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rs b/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rs
new file mode 100644
index 000000000..61a6b46a0
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0159_try_macro_fallback.rs
@@ -0,0 +1 @@
+fn foo() { try!(Ok(())); }
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rast b/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rast
new file mode 100644
index 000000000..05b89d1c3
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rast
@@ -0,0 +1,27 @@
+[email protected]
+  [email protected]
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected] "macro_rules"
+    [email protected] "!"
+    [email protected] " "
+    [email protected]
+      [email protected] "try"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] " "
+      [email protected]
+        [email protected] "("
+        [email protected] ")"
+      [email protected] " "
+      [email protected] "="
+      [email protected] ">"
+      [email protected] " "
+      [email protected]
+        [email protected] "{"
+        [email protected] "}"
+      [email protected] " "
+      [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rs b/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rs
new file mode 100644
index 000000000..2e2ab6e60
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0160_try_macro_rules.rs
@@ -0,0 +1 @@
+macro_rules! try { () => {} }
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index cee0248b6..0459807fc 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -20,7 +20,7 @@ globset = "0.4.4"
 itertools = "0.9.0"
 jod-thread = "0.1.0"
 log = "0.4.8"
-lsp-types = { version = "0.73.0", features = ["proposed"] }
+lsp-types = { version = "0.74.0", features = ["proposed"] }
 parking_lot = "0.10.0"
 pico-args = "0.3.1"
 rand = { version = "0.7.3", features = ["small_rng"] }
@@ -39,7 +39,7 @@ ra_prof = { path = "../ra_prof" }
 ra_project_model = { path = "../ra_project_model" }
 ra_syntax = { path = "../ra_syntax" }
 ra_text_edit = { path = "../ra_text_edit" }
-ra_vfs = "0.5.2"
+ra_vfs = "0.6.0"
 
 # This should only be used in CLI
 ra_db = { path = "../ra_db" }
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index 45b60768a..e22ab8402 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -16,7 +16,7 @@ pub fn server_capabilities() -> ServerCapabilities {
     ServerCapabilities {
         text_document_sync: Some(TextDocumentSyncCapability::Options(TextDocumentSyncOptions {
             open_close: Some(true),
-            change: Some(TextDocumentSyncKind::Full),
+            change: Some(TextDocumentSyncKind::Incremental),
             will_save: None,
             will_save_wait_until: None,
             save: Some(SaveOptions::default()),
diff --git a/crates/rust-analyzer/src/conv.rs b/crates/rust-analyzer/src/conv.rs
index ffe3ea84d..7be5ebcdb 100644
--- a/crates/rust-analyzer/src/conv.rs
+++ b/crates/rust-analyzer/src/conv.rs
@@ -150,7 +150,7 @@ impl ConvWith<(&LineIndex, LineEndings)> for CompletionItem {
             detail: self.detail().map(|it| it.to_string()),
             filter_text: Some(self.lookup().to_string()),
             kind: self.kind().map(|it| it.conv()),
-            text_edit: Some(text_edit),
+            text_edit: Some(text_edit.into()),
             additional_text_edits: Some(additional_text_edits),
             documentation: self.documentation().map(|it| it.conv()),
             deprecated: Some(self.deprecated()),
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index f3aef3f0f..0a0e616c9 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -6,9 +6,12 @@ mod subscriptions;
 pub(crate) mod pending_requests;
 
 use std::{
+    borrow::Cow,
     env,
     error::Error,
-    fmt, panic,
+    fmt,
+    ops::Range,
+    panic,
     path::PathBuf,
     sync::Arc,
     time::{Duration, Instant},
@@ -18,11 +21,12 @@ use crossbeam_channel::{never, select, unbounded, RecvError, Sender};
 use itertools::Itertools;
 use lsp_server::{Connection, ErrorCode, Message, Notification, Request, RequestId, Response};
 use lsp_types::{
-    NumberOrString, WorkDoneProgress, WorkDoneProgressBegin, WorkDoneProgressCreateParams,
-    WorkDoneProgressEnd, WorkDoneProgressReport,
+    DidChangeTextDocumentParams, NumberOrString, TextDocumentContentChangeEvent, WorkDoneProgress,
+    WorkDoneProgressBegin, WorkDoneProgressCreateParams, WorkDoneProgressEnd,
+    WorkDoneProgressReport,
 };
 use ra_flycheck::{url_from_path_with_drive_lowercasing, CheckTask};
-use ra_ide::{Canceled, FileId, LibraryData, SourceRootId};
+use ra_ide::{Canceled, FileId, LibraryData, LineIndex, SourceRootId};
 use ra_prof::profile;
 use ra_project_model::{PackageRoot, ProjectWorkspace};
 use ra_vfs::{VfsFile, VfsTask, Watch};
@@ -33,6 +37,7 @@ use threadpool::ThreadPool;
 
 use crate::{
     config::{Config, FilesWatcher},
+    conv::{ConvWith, TryConvWith},
     diagnostics::DiagnosticTask,
     main_loop::{
         pending_requests::{PendingRequest, PendingRequests},
@@ -579,12 +584,16 @@ fn on_notification(
         Err(not) => not,
     };
     let not = match notification_cast::<req::DidChangeTextDocument>(not) {
-        Ok(mut params) => {
-            let uri = params.text_document.uri;
+        Ok(params) => {
+            let DidChangeTextDocumentParams { text_document, content_changes } = params;
+            let world = state.snapshot();
+            let file_id = text_document.try_conv_with(&world)?;
+            let line_index = world.analysis().file_line_index(file_id)?;
+            let uri = text_document.uri;
             let path = uri.to_file_path().map_err(|()| format!("invalid uri: {}", uri))?;
-            let text =
-                params.content_changes.pop().ok_or_else(|| "empty changes".to_string())?.text;
-            state.vfs.write().change_file_overlay(path.as_path(), text);
+            state.vfs.write().change_file_overlay(&path, |old_text| {
+                apply_document_changes(old_text, Cow::Borrowed(&line_index), content_changes);
+            });
             return Ok(());
         }
         Err(not) => not,
@@ -653,6 +662,48 @@ fn on_notification(
     Ok(())
 }
 
+fn apply_document_changes(
+    old_text: &mut String,
+    mut line_index: Cow<'_, LineIndex>,
+    content_changes: Vec<TextDocumentContentChangeEvent>,
+) {
+    // The changes we got must be applied sequentially, but can cross lines so we
+    // have to keep our line index updated.
+    // Some clients (e.g. Code) sort the ranges in reverse. As an optimization, we
+    // remember the last valid line in the index and only rebuild it if needed.
+    enum IndexValid {
+        All,
+        UpToLine(u64),
+    }
+
+    impl IndexValid {
+        fn covers(&self, line: u64) -> bool {
+            match *self {
+                IndexValid::UpToLine(to) => to >= line,
+                _ => true,
+            }
+        }
+    }
+
+    let mut index_valid = IndexValid::All;
+    for change in content_changes {
+        match change.range {
+            Some(range) => {
+                if !index_valid.covers(range.start.line) {
+                    line_index = Cow::Owned(LineIndex::new(&old_text));
+                }
+                index_valid = IndexValid::UpToLine(range.start.line);
+                let range = range.conv_with(&line_index);
+                old_text.replace_range(Range::<usize>::from(range), &change.text);
+            }
+            None => {
+                *old_text = change.text;
+                index_valid = IndexValid::UpToLine(0);
+            }
+        }
+    }
+}
+
 fn on_check_task(
     task: CheckTask,
     world_state: &mut WorldState,
@@ -958,3 +1009,64 @@ where
 {
     Request::new(id, R::METHOD.to_string(), params)
 }
+
+#[cfg(test)]
+mod tests {
+    use std::borrow::Cow;
+
+    use lsp_types::{Position, Range, TextDocumentContentChangeEvent};
+    use ra_ide::LineIndex;
+
+    #[test]
+    fn apply_document_changes() {
+        fn run(text: &mut String, changes: Vec<TextDocumentContentChangeEvent>) {
+            let line_index = Cow::Owned(LineIndex::new(&text));
+            super::apply_document_changes(text, line_index, changes);
+        }
+
+        macro_rules! c {
+            [$($sl:expr, $sc:expr; $el:expr, $ec:expr => $text:expr),+] => {
+                vec![$(TextDocumentContentChangeEvent {
+                    range: Some(Range {
+                        start: Position { line: $sl, character: $sc },
+                        end: Position { line: $el, character: $ec },
+                    }),
+                    range_length: None,
+                    text: String::from($text),
+                }),+]
+            };
+        }
+
+        let mut text = String::new();
+        run(&mut text, vec![]);
+        assert_eq!(text, "");
+        run(
+            &mut text,
+            vec![TextDocumentContentChangeEvent {
+                range: None,
+                range_length: None,
+                text: String::from("the"),
+            }],
+        );
+        assert_eq!(text, "the");
+        run(&mut text, c![0, 3; 0, 3 => " quick"]);
+        assert_eq!(text, "the quick");
+        run(&mut text, c![0, 0; 0, 4 => "", 0, 5; 0, 5 => " foxes"]);
+        assert_eq!(text, "quick foxes");
+        run(&mut text, c![0, 11; 0, 11 => "\ndream"]);
+        assert_eq!(text, "quick foxes\ndream");
+        run(&mut text, c![1, 0; 1, 0 => "have "]);
+        assert_eq!(text, "quick foxes\nhave dream");
+        run(&mut text, c![0, 0; 0, 0 => "the ", 1, 4; 1, 4 => " quiet", 1, 16; 1, 16 => "s\n"]);
+        assert_eq!(text, "the quick foxes\nhave quiet dreams\n");
+        run(&mut text, c![0, 15; 0, 15 => "\n", 2, 17; 2, 17 => "\n"]);
+        assert_eq!(text, "the quick foxes\n\nhave quiet dreams\n\n");
+        run(
+            &mut text,
+            c![1, 0; 1, 0 => "DREAM", 2, 0; 2, 0 => "they ", 3, 0; 3, 0 => "DON'T THEY?"],
+        );
+        assert_eq!(text, "the quick foxes\nDREAM\nthey have quiet dreams\nDON'T THEY?\n");
+        run(&mut text, c![0, 10; 1, 5 => "", 2, 0; 2, 12 => ""]);
+        assert_eq!(text, "the quick \nthey have quiet dreams\n");
+    }
+}
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index 6caaf5f88..8db2dfa0c 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -326,10 +326,10 @@ pub fn handle_workspace_symbol(
 
 pub fn handle_goto_definition(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: req::GotoDefinitionParams,
 ) -> Result<Option<req::GotoDefinitionResponse>> {
     let _p = profile("handle_goto_definition");
-    let position = params.try_conv_with(&world)?;
+    let position = params.text_document_position_params.try_conv_with(&world)?;
     let nav_info = match world.analysis().goto_definition(position)? {
         None => return Ok(None),
         Some(it) => it,
@@ -340,10 +340,10 @@ pub fn handle_goto_definition(
 
 pub fn handle_goto_implementation(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: req::GotoImplementationParams,
 ) -> Result<Option<req::GotoImplementationResponse>> {
     let _p = profile("handle_goto_implementation");
-    let position = params.try_conv_with(&world)?;
+    let position = params.text_document_position_params.try_conv_with(&world)?;
     let nav_info = match world.analysis().goto_implementation(position)? {
         None => return Ok(None),
         Some(it) => it,
@@ -354,10 +354,10 @@ pub fn handle_goto_implementation(
 
 pub fn handle_goto_type_definition(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: req::GotoTypeDefinitionParams,
 ) -> Result<Option<req::GotoTypeDefinitionResponse>> {
     let _p = profile("handle_goto_type_definition");
-    let position = params.try_conv_with(&world)?;
+    let position = params.text_document_position_params.try_conv_with(&world)?;
     let nav_info = match world.analysis().goto_type_definition(position)? {
         None => return Ok(None),
         Some(it) => it,
@@ -487,10 +487,10 @@ pub fn handle_folding_range(
 
 pub fn handle_signature_help(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: req::SignatureHelpParams,
 ) -> Result<Option<req::SignatureHelp>> {
     let _p = profile("handle_signature_help");
-    let position = params.try_conv_with(&world)?;
+    let position = params.text_document_position_params.try_conv_with(&world)?;
     if let Some(call_info) = world.analysis().call_info(position)? {
         let concise = !world.config.call_info_full;
         let mut active_parameter = call_info.active_parameter.map(|it| it as i64);
@@ -509,12 +509,9 @@ pub fn handle_signature_help(
     }
 }
 
-pub fn handle_hover(
-    world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
-) -> Result<Option<Hover>> {
+pub fn handle_hover(world: WorldSnapshot, params: req::HoverParams) -> Result<Option<Hover>> {
     let _p = profile("handle_hover");
-    let position = params.try_conv_with(&world)?;
+    let position = params.text_document_position_params.try_conv_with(&world)?;
     let info = match world.analysis().hover(position)? {
         None => return Ok(None),
         Some(info) => info,
@@ -878,8 +875,14 @@ pub fn handle_code_lens(
             .map(|it| {
                 let range = it.node_range.conv_with(&line_index);
                 let pos = range.start;
-                let lens_params =
-                    req::TextDocumentPositionParams::new(params.text_document.clone(), pos);
+                let lens_params = req::GotoImplementationParams {
+                    text_document_position_params: req::TextDocumentPositionParams::new(
+                        params.text_document.clone(),
+                        pos,
+                    ),
+                    work_done_progress_params: Default::default(),
+                    partial_result_params: Default::default(),
+                };
                 CodeLens {
                     range,
                     command: None,
@@ -894,7 +897,7 @@ pub fn handle_code_lens(
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 enum CodeLensResolveData {
-    Impls(req::TextDocumentPositionParams),
+    Impls(req::GotoImplementationParams),
 }
 
 pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Result<CodeLens> {
@@ -927,7 +930,7 @@ pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Re
                 title,
                 command: "rust-analyzer.showReferences".into(),
                 arguments: Some(vec![
-                    to_value(&lens_params.text_document.uri).unwrap(),
+                    to_value(&lens_params.text_document_position_params.text_document.uri).unwrap(),
                     to_value(code_lens.range.start).unwrap(),
                     to_value(locations).unwrap(),
                 ]),
@@ -944,16 +947,16 @@ pub fn handle_code_lens_resolve(world: WorldSnapshot, code_lens: CodeLens) -> Re
 
 pub fn handle_document_highlight(
     world: WorldSnapshot,
-    params: req::TextDocumentPositionParams,
+    params: req::DocumentHighlightParams,
 ) -> Result<Option<Vec<DocumentHighlight>>> {
     let _p = profile("handle_document_highlight");
-    let file_id = params.text_document.try_conv_with(&world)?;
+    let file_id = params.text_document_position_params.text_document.try_conv_with(&world)?;
     let line_index = world.analysis().file_line_index(file_id)?;
 
-    let refs = match world
-        .analysis()
-        .find_all_refs(params.try_conv_with(&world)?, Some(SearchScope::single_file(file_id)))?
-    {
+    let refs = match world.analysis().find_all_refs(
+        params.text_document_position_params.try_conv_with(&world)?,
+        Some(SearchScope::single_file(file_id)),
+    )? {
         None => return Ok(None),
         Some(refs) => refs,
     };
diff --git a/crates/rust-analyzer/src/req.rs b/crates/rust-analyzer/src/req.rs
index ae3448892..0dae6bad4 100644
--- a/crates/rust-analyzer/src/req.rs
+++ b/crates/rust-analyzer/src/req.rs
@@ -8,14 +8,15 @@ pub use lsp_types::{
     notification::*, request::*, ApplyWorkspaceEditParams, CodeActionParams, CodeLens,
     CodeLensParams, CompletionParams, CompletionResponse, ConfigurationItem, ConfigurationParams,
     DiagnosticTag, DidChangeConfigurationParams, DidChangeWatchedFilesParams,
-    DidChangeWatchedFilesRegistrationOptions, DocumentOnTypeFormattingParams, DocumentSymbolParams,
-    DocumentSymbolResponse, FileSystemWatcher, Hover, InitializeResult, MessageType,
-    PartialResultParams, ProgressParams, ProgressParamsValue, ProgressToken,
-    PublishDiagnosticsParams, ReferenceParams, Registration, RegistrationParams, SelectionRange,
-    SelectionRangeParams, SemanticTokensParams, SemanticTokensRangeParams,
+    DidChangeWatchedFilesRegistrationOptions, DocumentHighlightParams,
+    DocumentOnTypeFormattingParams, DocumentSymbolParams, DocumentSymbolResponse,
+    FileSystemWatcher, GotoDefinitionParams, GotoDefinitionResponse, Hover, HoverParams,
+    InitializeResult, MessageType, PartialResultParams, ProgressParams, ProgressParamsValue,
+    ProgressToken, PublishDiagnosticsParams, ReferenceParams, Registration, RegistrationParams,
+    SelectionRange, SelectionRangeParams, SemanticTokensParams, SemanticTokensRangeParams,
     SemanticTokensRangeResult, SemanticTokensResult, ServerCapabilities, ShowMessageParams,
-    SignatureHelp, SymbolKind, TextDocumentEdit, TextDocumentPositionParams, TextEdit,
-    WorkDoneProgressParams, WorkspaceEdit, WorkspaceSymbolParams,
+    SignatureHelp, SignatureHelpParams, SymbolKind, TextDocumentEdit, TextDocumentPositionParams,
+    TextEdit, WorkDoneProgressParams, WorkspaceEdit, WorkspaceSymbolParams,
 };
 use std::path::PathBuf;
 
diff --git a/crates/rust-analyzer/src/semantic_tokens.rs b/crates/rust-analyzer/src/semantic_tokens.rs
index 71f4f58a3..2dc5cb119 100644
--- a/crates/rust-analyzer/src/semantic_tokens.rs
+++ b/crates/rust-analyzer/src/semantic_tokens.rs
@@ -4,64 +4,69 @@ use std::ops;
 
 use lsp_types::{Range, SemanticToken, SemanticTokenModifier, SemanticTokenType, SemanticTokens};
 
-pub(crate) const ATTRIBUTE: SemanticTokenType = SemanticTokenType::new("attribute");
-pub(crate) const BUILTIN_TYPE: SemanticTokenType = SemanticTokenType::new("builtinType");
-pub(crate) const ENUM_MEMBER: SemanticTokenType = SemanticTokenType::new("enumMember");
-pub(crate) const LIFETIME: SemanticTokenType = SemanticTokenType::new("lifetime");
-pub(crate) const TYPE_ALIAS: SemanticTokenType = SemanticTokenType::new("typeAlias");
-pub(crate) const UNION: SemanticTokenType = SemanticTokenType::new("union");
-pub(crate) const UNRESOLVED_REFERENCE: SemanticTokenType =
-    SemanticTokenType::new("unresolvedReference");
-pub(crate) const FORMAT_SPECIFIER: SemanticTokenType = SemanticTokenType::new("formatSpecifier");
-
-pub(crate) const CONSTANT: SemanticTokenModifier = SemanticTokenModifier::new("constant");
-pub(crate) const CONTROL_FLOW: SemanticTokenModifier = SemanticTokenModifier::new("controlFlow");
-pub(crate) const MUTABLE: SemanticTokenModifier = SemanticTokenModifier::new("mutable");
-pub(crate) const UNSAFE: SemanticTokenModifier = SemanticTokenModifier::new("unsafe");
-
-pub(crate) const SUPPORTED_TYPES: &[SemanticTokenType] = &[
-    SemanticTokenType::COMMENT,
-    SemanticTokenType::KEYWORD,
-    SemanticTokenType::STRING,
-    SemanticTokenType::NUMBER,
-    SemanticTokenType::REGEXP,
-    SemanticTokenType::OPERATOR,
-    SemanticTokenType::NAMESPACE,
-    SemanticTokenType::TYPE,
-    SemanticTokenType::STRUCT,
-    SemanticTokenType::CLASS,
-    SemanticTokenType::INTERFACE,
-    SemanticTokenType::ENUM,
-    SemanticTokenType::TYPE_PARAMETER,
-    SemanticTokenType::FUNCTION,
-    SemanticTokenType::MEMBER,
-    SemanticTokenType::PROPERTY,
-    SemanticTokenType::MACRO,
-    SemanticTokenType::VARIABLE,
-    SemanticTokenType::PARAMETER,
-    SemanticTokenType::LABEL,
-    ATTRIBUTE,
-    BUILTIN_TYPE,
-    ENUM_MEMBER,
-    LIFETIME,
-    TYPE_ALIAS,
-    UNION,
-    UNRESOLVED_REFERENCE,
-    FORMAT_SPECIFIER,
+macro_rules! define_semantic_token_types {
+    ($(($ident:ident, $string:literal)),*$(,)?) => {
+        $(pub(crate) const $ident: SemanticTokenType = SemanticTokenType::new($string);)*
+
+        pub(crate) const SUPPORTED_TYPES: &[SemanticTokenType] = &[
+            SemanticTokenType::COMMENT,
+            SemanticTokenType::KEYWORD,
+            SemanticTokenType::STRING,
+            SemanticTokenType::NUMBER,
+            SemanticTokenType::REGEXP,
+            SemanticTokenType::OPERATOR,
+            SemanticTokenType::NAMESPACE,
+            SemanticTokenType::TYPE,
+            SemanticTokenType::STRUCT,
+            SemanticTokenType::CLASS,
+            SemanticTokenType::INTERFACE,
+            SemanticTokenType::ENUM,
+            SemanticTokenType::TYPE_PARAMETER,
+            SemanticTokenType::FUNCTION,
+            SemanticTokenType::MEMBER,
+            SemanticTokenType::PROPERTY,
+            SemanticTokenType::MACRO,
+            SemanticTokenType::VARIABLE,
+            SemanticTokenType::PARAMETER,
+            SemanticTokenType::LABEL,
+            $($ident),*
+        ];
+    };
+}
+
+define_semantic_token_types![
+    (ATTRIBUTE, "attribute"),
+    (BUILTIN_TYPE, "builtinType"),
+    (ENUM_MEMBER, "enumMember"),
+    (LIFETIME, "lifetime"),
+    (TYPE_ALIAS, "typeAlias"),
+    (UNION, "union"),
+    (UNRESOLVED_REFERENCE, "unresolvedReference"),
+    (FORMAT_SPECIFIER, "formatSpecifier"),
 ];
 
-pub(crate) const SUPPORTED_MODIFIERS: &[SemanticTokenModifier] = &[
-    SemanticTokenModifier::DOCUMENTATION,
-    SemanticTokenModifier::DECLARATION,
-    SemanticTokenModifier::DEFINITION,
-    SemanticTokenModifier::STATIC,
-    SemanticTokenModifier::ABSTRACT,
-    SemanticTokenModifier::DEPRECATED,
-    SemanticTokenModifier::READONLY,
-    CONSTANT,
-    MUTABLE,
-    UNSAFE,
-    CONTROL_FLOW,
+macro_rules! define_semantic_token_modifiers {
+    ($(($ident:ident, $string:literal)),*$(,)?) => {
+        $(pub(crate) const $ident: SemanticTokenModifier = SemanticTokenModifier::new($string);)*
+
+        pub(crate) const SUPPORTED_MODIFIERS: &[SemanticTokenModifier] = &[
+            SemanticTokenModifier::DOCUMENTATION,
+            SemanticTokenModifier::DECLARATION,
+            SemanticTokenModifier::DEFINITION,
+            SemanticTokenModifier::STATIC,
+            SemanticTokenModifier::ABSTRACT,
+            SemanticTokenModifier::DEPRECATED,
+            SemanticTokenModifier::READONLY,
+            $($ident),*
+        ];
+    };
+}
+
+define_semantic_token_modifiers![
+    (CONSTANT, "constant"),
+    (CONTROL_FLOW, "controlFlow"),
+    (MUTABLE, "mutable"),
+    (UNSAFE, "unsafe"),
 ];
 
 #[derive(Default)]
diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/heavy_tests/main.rs
index f6245ddd4..07b8114c6 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/main.rs
@@ -4,8 +4,8 @@ use std::{collections::HashMap, path::PathBuf, time::Instant};
 
 use lsp_types::{
     CodeActionContext, DidOpenTextDocumentParams, DocumentFormattingParams, FormattingOptions,
-    PartialResultParams, Position, Range, TextDocumentItem, TextDocumentPositionParams,
-    WorkDoneProgressParams,
+    GotoDefinitionParams, HoverParams, PartialResultParams, Position, Range, TextDocumentItem,
+    TextDocumentPositionParams, WorkDoneProgressParams,
 };
 use rust_analyzer::req::{
     CodeActionParams, CodeActionRequest, Completion, CompletionParams, DidOpenTextDocument,
@@ -610,10 +610,14 @@ fn main() { message(); }
     })
     .server();
     server.wait_until_workspace_is_loaded();
-    let res = server.send_request::<GotoDefinition>(TextDocumentPositionParams::new(
-        server.doc_id("src/main.rs"),
-        Position::new(2, 15),
-    ));
+    let res = server.send_request::<GotoDefinition>(GotoDefinitionParams {
+        text_document_position_params: TextDocumentPositionParams::new(
+            server.doc_id("src/main.rs"),
+            Position::new(2, 15),
+        ),
+        work_done_progress_params: Default::default(),
+        partial_result_params: Default::default(),
+    });
     assert!(format!("{}", res).contains("hello.rs"));
 }
 
@@ -692,10 +696,13 @@ pub fn foo(_input: TokenStream) -> TokenStream {
     .root("bar")
     .server();
     server.wait_until_workspace_is_loaded();
-    let res = server.send_request::<HoverRequest>(TextDocumentPositionParams::new(
-        server.doc_id("foo/src/main.rs"),
-        Position::new(7, 9),
-    ));
+    let res = server.send_request::<HoverRequest>(HoverParams {
+        text_document_position_params: TextDocumentPositionParams::new(
+            server.doc_id("foo/src/main.rs"),
+            Position::new(7, 9),
+        ),
+        work_done_progress_params: Default::default(),
+    });
 
     let value = res.get("contents").unwrap().get("value").unwrap().to_string();
     assert_eq!(value, r#""```rust\nfoo::Bar\nfn bar()\n```""#)
diff --git a/docs/dev/syntax.md b/docs/dev/syntax.md
index 4dd1de659..33973ffec 100644
--- a/docs/dev/syntax.md
+++ b/docs/dev/syntax.md
@@ -35,7 +35,7 @@ The syntax tree consists of three layers:
 * AST
 
 Of these, only GreenNodes store the actual data, the other two layers are (non-trivial) views into green tree.
-Red-green terminology comes from Roslyn ([link](https://docs.microsoft.com/en-ie/archive/blogs/ericlippert/persistence-facades-and-roslyns-red-green-trees)) and gives the name to the `rowan` library. Green and syntax nodes are defined in rowan, ast is defined in rust-analyzer.
+Red-green terminology comes from Roslyn ([link](https://ericlippert.com/2012/06/08/red-green-trees/)) and gives the name to the `rowan` library. Green and syntax nodes are defined in rowan, ast is defined in rust-analyzer.
 
 Syntax trees are a semi-transient data structure.
 In general, frontend does not keep syntax trees for all files in memory.
diff --git a/docs/user/features.md b/docs/user/features.md
index 56d2969fd..b9a365fc1 100644
--- a/docs/user/features.md
+++ b/docs/user/features.md
@@ -140,8 +140,8 @@ space or `;` depending on the return type of the function.
 When completing a function call, `()` are automatically inserted. If a function
 takes arguments, the cursor is positioned inside the parenthesis.
 
-There are postifx completions, which can be triggerd by typing something like
-`foo().if`. The word after `.` determines postifx completion. Possible variants are:
+There are postfix completions, which can be triggered by typing something like
+`foo().if`. The word after `.` determines postfix completion. Possible variants are:
 
 - `expr.if` -> `if expr {}`
 - `expr.match` -> `match expr {}`
diff --git a/docs/user/readme.adoc b/docs/user/readme.adoc
index 76d065d35..4cb1e23e8 100644
--- a/docs/user/readme.adoc
+++ b/docs/user/readme.adoc
@@ -111,7 +111,7 @@ Here are some useful self-diagnostic commands:
 === rust-analyzer Language Server Binary
 
 Other editors generally require the `rust-analyzer` binary to be in `$PATH`.
-You can download the pre-built binary from the https://github.com/rust-analyzer/rust-analyzer/releases[releases] page. Typically, you then need to rename the binary for your platform, e.g. `rust-analyzer-mac` if you're on Mac OS, to `rust-analzyer` and make it executable in addition to moving it into a directory in your `$PATH`.
+You can download the pre-built binary from the https://github.com/rust-analyzer/rust-analyzer/releases[releases] page. Typically, you then need to rename the binary for your platform, e.g. `rust-analyzer-mac` if you're on Mac OS, to `rust-analyzer` and make it executable in addition to moving it into a directory in your `$PATH`.
 
 On Linux to install the `rust-analyzer` binary into `~/.local/bin`, this commands could be used
 
@@ -169,13 +169,15 @@ The are several LSP client implementations for vim:
 
 1. Install coc.nvim by following the instructions at
    https://github.com/neoclide/coc.nvim[coc.nvim]
-   (nodejs required)
+   (Node.js required)
 2. Run `:CocInstall coc-rust-analyzer` to install
    https://github.com/fannheyward/coc-rust-analyzer[coc-rust-analyzer],
    this extension implements _most_ of the features supported in the VSCode extension:
+   * automatically install and upgrade stable/nightly releases
    * same configurations as VSCode extension, `rust-analyzer.serverPath`, `rust-analyzer.cargo.features` etc.
    * same commands too, `rust-analyzer.analyzerStatus`, `rust-analyzer.ssr` etc.
-   * highlighting and inlay_hints are not implemented yet
+   * inlay hints for method chaining support, _Neovim Only_
+   * semantic highlighting is not implemented yet
 
 ==== LanguageClient-neovim
 
@@ -195,7 +197,7 @@ let g:LanguageClient_serverCommands = {
 ==== YouCompleteMe
 
 1. Install YouCompleteMe by following the instructions
-  https://ycm-core.github.io/YouCompleteMe/#rust-semantic-completion[here]
+  https://github.com/ycm-core/lsp-examples#rust-rust-analyzer[here]
 
 2. Configure by adding this to your vim/neovim config file (replacing the existing Rust-specific line if it exists):
 +
@@ -212,6 +214,21 @@ let g:ycm_language_server =
 \ ]
 ----
 
+==== ALE
+
+To add the LSP server to https://github.com/dense-analysis/ale[ale]:
+
+[source,vim]
+----
+call ale#linter#Define('rust', {
+\   'name': 'rust-analyzer',
+\   'lsp': 'stdio',
+\   'executable': 'rust-analyzer',
+\   'command': '%e',
+\   'project_root': '.',
+\})
+----
+
 ==== nvim-lsp
 
 NeoVim 0.5 (not yet released) has built-in language server support.
@@ -229,9 +246,9 @@ You also need the `LSP` package. To install it:
    * Type `Install Package Control`, press enter
 2. In the command palette, run `Package control: Install package`, and in the list that pops up, type `LSP` and press enter.
 
-Finally, with your Rust project open, in the command palette, run `LSP: Enable Language Server In Project` or `LSP: Enable Language Server Globally`, then select `rust-analyzer` in the list that pops up to enable the rust-analyzer LSP. The latter means that rust-analzyer is enabled by default in Rust projects.
+Finally, with your Rust project open, in the command palette, run `LSP: Enable Language Server In Project` or `LSP: Enable Language Server Globally`, then select `rust-analyzer` in the list that pops up to enable the rust-analyzer LSP. The latter means that rust-analyzer is enabled by default in Rust projects.
 
-If it worked, you should see "rust-analzyer, Line X, Column Y" on the left side of the bottom bar, and after waiting a bit, functionality like tooltips on hovering over variables should become available.
+If it worked, you should see "rust-analyzer, Line X, Column Y" on the left side of the bottom bar, and after waiting a bit, functionality like tooltips on hovering over variables should become available.
 
 If you get an error saying `No such file or directory: 'rust-analyzer'`, see the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>> section on installing the language server binary.
 
diff --git a/editors/code/package.json b/editors/code/package.json
index b8aaa07d8..d30673791 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -27,6 +27,7 @@
     "scripts": {
         "vscode:prepublish": "tsc && rollup -c",
         "package": "vsce package -o rust-analyzer.vsix",
+        "build": "tsc",
         "watch": "tsc --watch",
         "lint": "tsfmt --verify && eslint -c .eslintrc.js --ext ts ./src",
         "fix": " tsfmt -r       && eslint -c .eslintrc.js --ext ts ./src --fix"
@@ -388,6 +389,28 @@
                     "description": "Enable Proc macro support, cargo.loadOutDirsFromCheck must be enabled.",
                     "type": "boolean",
                     "default": false
+                },
+                "rust-analyzer.debug.engine": {
+                    "type": "string",
+                    "enum": [
+                        "auto",
+                        "vadimcn.vscode-lldb",
+                        "ms-vscode.cpptools"
+                    ],
+                    "default": "auto",
+                    "description": "Preffered debug engine.",
+                    "markdownEnumDescriptions": [
+                        "First try to use [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb), if it's not installed try to use [MS C++ tools](https://marketplace.visualstudio.com/items?itemName=ms-vscode.cpptools).",
+                        "Use [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb)",
+                        "Use [MS C++ tools](https://marketplace.visualstudio.com/items?itemName=ms-vscode.cpptools)"
+                    ]
+                },
+                "rust-analyzer.debug.sourceFileMap": {
+                    "type": "object",
+                    "description": "Optional source file mappings passed to the debug engine.",
+                    "default": {
+                        "/rustc/<id>": "${env:USERPROFILE}/.rustup/toolchains/<toolchain-id>/lib/rustlib/src/rust"
+                    }
                 }
             }
         },
diff --git a/editors/code/src/cargo.ts b/editors/code/src/cargo.ts
new file mode 100644
index 000000000..a328ba9bd
--- /dev/null
+++ b/editors/code/src/cargo.ts
@@ -0,0 +1,106 @@
+import * as cp from 'child_process';
+import * as readline from 'readline';
+import { OutputChannel } from 'vscode';
+
+interface CompilationArtifact {
+    fileName: string;
+    name: string;
+    kind: string;
+    isTest: boolean;
+}
+
+export class Cargo {
+    rootFolder: string;
+    env?: Record<string, string>;
+    output: OutputChannel;
+
+    public constructor(cargoTomlFolder: string, output: OutputChannel, env: Record<string, string> | undefined = undefined) {
+        this.rootFolder = cargoTomlFolder;
+        this.output = output;
+        this.env = env;
+    }
+
+    public async artifactsFromArgs(cargoArgs: string[]): Promise<CompilationArtifact[]> {
+        const artifacts: CompilationArtifact[] = [];
+
+        try {
+            await this.runCargo(cargoArgs,
+                message => {
+                    if (message.reason === 'compiler-artifact' && message.executable) {
+                        const isBinary = message.target.crate_types.includes('bin');
+                        const isBuildScript = message.target.kind.includes('custom-build');
+                        if ((isBinary && !isBuildScript) || message.profile.test) {
+                            artifacts.push({
+                                fileName: message.executable,
+                                name: message.target.name,
+                                kind: message.target.kind[0],
+                                isTest: message.profile.test
+                            });
+                        }
+                    }
+                    else if (message.reason === 'compiler-message') {
+                        this.output.append(message.message.rendered);
+                    }
+                },
+                stderr => {
+                    this.output.append(stderr);
+                }
+            );
+        }
+        catch (err) {
+            this.output.show(true);
+            throw new Error(`Cargo invocation has failed: ${err}`);
+        }
+
+        return artifacts;
+    }
+
+    public async executableFromArgs(args: string[]): Promise<string> {
+        const cargoArgs = [...args]; // to remain  args unchanged
+        cargoArgs.push("--message-format=json");
+
+        const artifacts = await this.artifactsFromArgs(cargoArgs);
+
+        if (artifacts.length === 0) {
+            throw new Error('No compilation artifacts');
+        } else if (artifacts.length > 1) {
+            throw new Error('Multiple compilation artifacts are not supported.');
+        }
+
+        return artifacts[0].fileName;
+    }
+
+    runCargo(
+        cargoArgs: string[],
+        onStdoutJson: (obj: any) => void,
+        onStderrString: (data: string) => void
+    ): Promise<number> {
+        return new Promise<number>((resolve, reject) => {
+            const cargo = cp.spawn('cargo', cargoArgs, {
+                stdio: ['ignore', 'pipe', 'pipe'],
+                cwd: this.rootFolder,
+                env: this.env,
+            });
+
+            cargo.on('error', err => {
+                reject(new Error(`could not launch cargo: ${err}`));
+            });
+            cargo.stderr.on('data', chunk => {
+                onStderrString(chunk.toString());
+            });
+
+            const rl = readline.createInterface({ input: cargo.stdout });
+            rl.on('line', line => {
+                const message = JSON.parse(line);
+                onStdoutJson(message);
+            });
+
+            cargo.on('exit', (exitCode, _) => {
+                if (exitCode === 0)
+                    resolve(exitCode);
+                else
+                    reject(new Error(`exit code: ${exitCode}.`));
+            });
+        });
+    }
+}
\ No newline at end of file
diff --git a/editors/code/src/commands/runnables.ts b/editors/code/src/commands/runnables.ts
index 2635a1440..d77e8188c 100644
--- a/editors/code/src/commands/runnables.ts
+++ b/editors/code/src/commands/runnables.ts
@@ -1,8 +1,10 @@
 import * as vscode from 'vscode';
 import * as lc from 'vscode-languageclient';
 import * as ra from '../rust-analyzer-api';
+import * as os from "os";
 
 import { Ctx, Cmd } from '../ctx';
+import { Cargo } from '../cargo';
 
 export function run(ctx: Ctx): Cmd {
     let prevRunnable: RunnableQuickPick | undefined;
@@ -62,25 +64,69 @@ export function runSingle(ctx: Ctx): Cmd {
     };
 }
 
+function getLldbDebugConfig(config: ra.Runnable, sourceFileMap: Record<string, string>): vscode.DebugConfiguration {
+    return {
+        type: "lldb",
+        request: "launch",
+        name: config.label,
+        cargo: {
+            args: config.args,
+        },
+        args: config.extraArgs,
+        cwd: config.cwd,
+        sourceMap: sourceFileMap
+    };
+}
+
+const debugOutput = vscode.window.createOutputChannel("Debug");
+
+async function getCppvsDebugConfig(config: ra.Runnable, sourceFileMap: Record<string, string>): Promise<vscode.DebugConfiguration> {
+    debugOutput.clear();
+
+    const cargo = new Cargo(config.cwd || '.', debugOutput);
+    const executable = await cargo.executableFromArgs(config.args);
+
+    // if we are here, there were no compilation errors.
+    return {
+        type: (os.platform() === "win32") ? "cppvsdbg" : 'cppdbg',
+        request: "launch",
+        name: config.label,
+        program: executable,
+        args: config.extraArgs,
+        cwd: config.cwd,
+        sourceFileMap: sourceFileMap,
+    };
+}
+
 export function debugSingle(ctx: Ctx): Cmd {
     return async (config: ra.Runnable) => {
         const editor = ctx.activeRustEditor;
         if (!editor) return;
-        if (!vscode.extensions.getExtension("vadimcn.vscode-lldb")) {
-            vscode.window.showErrorMessage("Install `vadimcn.vscode-lldb` extension for debugging");
+
+        const lldbId = "vadimcn.vscode-lldb";
+        const cpptoolsId = "ms-vscode.cpptools";
+
+        const debugEngineId = ctx.config.debug.engine;
+        let debugEngine = null;
+        if (debugEngineId === "auto") {
+            debugEngine = vscode.extensions.getExtension(lldbId);
+            if (!debugEngine) {
+                debugEngine = vscode.extensions.getExtension(cpptoolsId);
+            }
+        }
+        else {
+            debugEngine = vscode.extensions.getExtension(debugEngineId);
+        }
+
+        if (!debugEngine) {
+            vscode.window.showErrorMessage(`Install [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=${lldbId})`
+                + ` or [MS C++ tools](https://marketplace.visualstudio.com/items?itemName=${cpptoolsId}) extension for debugging.`);
             return;
         }
 
-        const debugConfig = {
-            type: "lldb",
-            request: "launch",
-            name: config.label,
-            cargo: {
-                args: config.args,
-            },
-            args: config.extraArgs,
-            cwd: config.cwd
-        };
+        const debugConfig = lldbId === debugEngine.id
+            ? getLldbDebugConfig(config, ctx.config.debug.sourceFileMap)
+            : await getCppvsDebugConfig(config, ctx.config.debug.sourceFileMap);
 
         return vscode.debug.startDebugging(undefined, debugConfig);
     };
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index 3b2eec8ba..110e54180 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -92,7 +92,6 @@ export class Config {
     get askBeforeDownload() { return this.get<boolean>("updates.askBeforeDownload"); }
     get traceExtension() { return this.get<boolean>("trace.extension"); }
 
-
     get inlayHints() {
         return {
             typeHints: this.get<boolean>("inlayHints.typeHints"),
@@ -107,4 +106,12 @@ export class Config {
             command: this.get<string>("checkOnSave.command"),
         };
     }
+
+    get debug() {
+        return {
+            engine: this.get<string>("debug.engine"),
+            sourceFileMap: this.get<Record<string, string>>("debug.sourceFileMap"),
+        };
+    }
+
 }
diff --git a/xtask/src/ast_src.rs b/xtask/src/ast_src.rs
index 9c02f7c6f..bdd42cb76 100644
--- a/xtask/src/ast_src.rs
+++ b/xtask/src/ast_src.rs
@@ -162,7 +162,6 @@ pub(crate) const KINDS_SRC: KindsSrc = KindsSrc {
         "RECORD_LIT",
         "RECORD_FIELD_LIST",
         "RECORD_FIELD",
-        "TRY_BLOCK_EXPR",
         "BOX_EXPR",
         // postfix
         "CALL_EXPR",
@@ -440,7 +439,6 @@ pub(crate) const AST_SRC: AstSrc = AstSrc {
         }
         struct IfExpr: AttrsOwner { T![if], Condition }
         struct LoopExpr: AttrsOwner, LoopBodyOwner { T![loop] }
-        struct TryBlockExpr: AttrsOwner { T![try], body: BlockExpr }
         struct ForExpr: AttrsOwner, LoopBodyOwner {
             T![for],
             Pat,
@@ -451,7 +449,7 @@ pub(crate) const AST_SRC: AstSrc = AstSrc {
         struct ContinueExpr: AttrsOwner { T![continue], T![lifetime] }
         struct BreakExpr: AttrsOwner { T![break], T![lifetime], Expr }
         struct Label { T![lifetime] }
-        struct BlockExpr: AttrsOwner { Label, T![unsafe], Block  }
+        struct BlockExpr: AttrsOwner { Label, T![unsafe], T![async], Block }
         struct ReturnExpr: AttrsOwner { Expr }
         struct CallExpr: ArgListOwner { Expr }
         struct MethodCallExpr: AttrsOwner, ArgListOwner {
@@ -595,7 +593,7 @@ pub(crate) const AST_SRC: AstSrc = AstSrc {
             qualifier: Path,
         }
         struct PathSegment {
-            T![::], T![<], NameRef, TypeArgList, ParamList, RetType, PathType, T![>]
+            T![::], T![crate], T![<], NameRef, TypeArgList, ParamList, RetType, PathType, T![>]
         }
         struct TypeArgList {
             T![::],
@@ -722,7 +720,6 @@ pub(crate) const AST_SRC: AstSrc = AstSrc {
             FieldExpr,
             AwaitExpr,
             TryExpr,
-            TryBlockExpr,
             CastExpr,
             RefExpr,
             PrefixExpr,
diff --git a/xtask/src/dist.rs b/xtask/src/dist.rs
index a56eeef8d..aef68089e 100644
--- a/xtask/src/dist.rs
+++ b/xtask/src/dist.rs
@@ -50,21 +50,19 @@ fn dist_server(nightly: bool) -> Result<()> {
     if cfg!(target_os = "linux") {
         std::env::set_var("CC", "clang");
         run!(
-            "cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --release
-             --target x86_64-unknown-linux-musl
-            "
+            "cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --release"
             // We'd want to add, but that requires setting the right linker somehow
             // --features=jemalloc
         )?;
         if !nightly {
-            run!("strip ./target/x86_64-unknown-linux-musl/release/rust-analyzer")?;
+            run!("strip ./target/release/rust-analyzer")?;
         }
     } else {
         run!("cargo build --manifest-path ./crates/rust-analyzer/Cargo.toml --bin rust-analyzer --release")?;
     }
 
     let (src, dst) = if cfg!(target_os = "linux") {
-        ("./target/x86_64-unknown-linux-musl/release/rust-analyzer", "./dist/rust-analyzer-linux")
+        ("./target/release/rust-analyzer", "./dist/rust-analyzer-linux")
     } else if cfg!(target_os = "windows") {
         ("./target/release/rust-analyzer.exe", "./dist/rust-analyzer-windows.exe")
     } else if cfg!(target_os = "macos") {
diff --git a/xtask/src/lib.rs b/xtask/src/lib.rs
index ec824a518..2b7a461e5 100644
--- a/xtask/src/lib.rs
+++ b/xtask/src/lib.rs
@@ -10,23 +10,19 @@ pub mod pre_commit;
 pub mod codegen;
 mod ast_src;
 
-use anyhow::Context;
 use std::{
     env,
-    io::Write,
     path::{Path, PathBuf},
-    process::{Command, Stdio},
 };
+
 use walkdir::{DirEntry, WalkDir};
 
 use crate::{
     codegen::Mode,
-    not_bash::{date_iso, fs2, pushd, rm_rf, run},
+    not_bash::{date_iso, fs2, pushd, pushenv, rm_rf, run},
 };
 
-pub use anyhow::Result;
-
-const TOOLCHAIN: &str = "stable";
+pub use anyhow::{bail, Context as _, Result};
 
 pub fn project_root() -> PathBuf {
     Path::new(
@@ -55,54 +51,44 @@ pub fn rust_files(path: &Path) -> impl Iterator<Item = PathBuf> {
 
 pub fn run_rustfmt(mode: Mode) -> Result<()> {
     let _dir = pushd(project_root());
+    let _e = pushenv("RUSTUP_TOOLCHAIN", "stable");
     ensure_rustfmt()?;
-
-    let check = if mode == Mode::Verify { "--check" } else { "" };
-    run!("rustup run {} -- cargo fmt -- {}", TOOLCHAIN, check)?;
+    match mode {
+        Mode::Overwrite => run!("cargo fmt"),
+        Mode::Verify => run!("cargo fmt -- --check"),
+    }?;
     Ok(())
 }
 
 fn reformat(text: impl std::fmt::Display) -> Result<String> {
+    let _e = pushenv("RUSTUP_TOOLCHAIN", "stable");
     ensure_rustfmt()?;
-    let mut rustfmt = Command::new("rustup")
-        .args(&["run", TOOLCHAIN, "--", "rustfmt", "--config-path"])
-        .arg(project_root().join("rustfmt.toml"))
-        .args(&["--config", "fn_single_line=true"])
-        .stdin(Stdio::piped())
-        .stdout(Stdio::piped())
-        .spawn()?;
-    write!(rustfmt.stdin.take().unwrap(), "{}", text)?;
-    let output = rustfmt.wait_with_output()?;
-    let stdout = String::from_utf8(output.stdout)?;
+    let stdout = run!(
+        "rustfmt --config-path {} --config fn_single_line=true", project_root().join("rustfmt.toml").display();
+        <text.to_string().as_bytes()
+    )?;
     let preamble = "Generated file, do not edit by hand, see `xtask/src/codegen`";
-    Ok(format!("//! {}\n\n{}", preamble, stdout))
+    Ok(format!("//! {}\n\n{}\n", preamble, stdout))
 }
 
 fn ensure_rustfmt() -> Result<()> {
-    match Command::new("rustup")
-        .args(&["run", TOOLCHAIN, "--", "cargo", "fmt", "--version"])
-        .stderr(Stdio::null())
-        .stdout(Stdio::null())
-        .status()
-    {
-        Ok(status) if status.success() => return Ok(()),
-        _ => (),
-    };
-    run!("rustup toolchain install {}", TOOLCHAIN)?;
-    run!("rustup component add rustfmt --toolchain {}", TOOLCHAIN)?;
+    let out = run!("rustfmt --version")?;
+    if !out.contains("stable") {
+        bail!(
+            "Failed to run rustfmt from toolchain 'stable'. \
+             Please run `rustup component add rustfmt --toolchain stable` to install it.",
+        )
+    }
     Ok(())
 }
 
 pub fn run_clippy() -> Result<()> {
-    match Command::new("rustup")
-        .args(&["run", TOOLCHAIN, "--", "cargo", "clippy", "--version"])
-        .stderr(Stdio::null())
-        .stdout(Stdio::null())
-        .status()
-    {
-        Ok(status) if status.success() => (),
-        _ => install_clippy().context("install clippy")?,
-    };
+    if run!("cargo clippy --version").is_err() {
+        bail!(
+            "Failed run cargo clippy. \
+            Please run `rustup component add clippy` to install it.",
+        )
+    }
 
     let allowed_lints = [
         "clippy::collapsible_if",
@@ -110,27 +96,24 @@ pub fn run_clippy() -> Result<()> {
         "clippy::nonminimal_bool",
         "clippy::redundant_pattern_matching",
     ];
-    run!(
-        "rustup run {} -- cargo clippy --all-features --all-targets -- -A {}",
-        TOOLCHAIN,
-        allowed_lints.join(" -A ")
-    )?;
-    Ok(())
-}
-
-fn install_clippy() -> Result<()> {
-    run!("rustup toolchain install {}", TOOLCHAIN)?;
-    run!("rustup component add clippy --toolchain {}", TOOLCHAIN)?;
+    run!("cargo clippy --all-features --all-targets -- -A {}", allowed_lints.join(" -A "))?;
     Ok(())
 }
 
 pub fn run_fuzzer() -> Result<()> {
     let _d = pushd("./crates/ra_syntax");
+    let _e = pushenv("RUSTUP_TOOLCHAIN", "nightly");
     if run!("cargo fuzz --help").is_err() {
         run!("cargo install cargo-fuzz")?;
     };
 
-    run!("rustup run nightly -- cargo fuzz run parser")?;
+    // Expecting nightly rustc
+    let out = run!("rustc --version")?;
+    if !out.contains("nightly") {
+        bail!("fuzz tests require nightly rustc")
+    }
+
+    run!("cargo fuzz run parser")?;
     Ok(())
 }
 
diff --git a/xtask/src/not_bash.rs b/xtask/src/not_bash.rs
index ef1699934..a6431e586 100644
--- a/xtask/src/not_bash.rs
+++ b/xtask/src/not_bash.rs
@@ -3,6 +3,8 @@
 use std::{
     cell::RefCell,
     env,
+    ffi::OsString,
+    io::Write,
     path::{Path, PathBuf},
     process::{Command, Stdio},
 };
@@ -57,7 +59,10 @@ macro_rules! _run {
         run!($($expr),*; echo = true)
     };
     ($($expr:expr),* ; echo = $echo:expr) => {
-        $crate::not_bash::run_process(format!($($expr),*), $echo)
+        $crate::not_bash::run_process(format!($($expr),*), $echo, None)
+    };
+    ($($expr:expr),* ;  <$stdin:expr) => {
+        $crate::not_bash::run_process(format!($($expr),*), false, Some($stdin))
     };
 }
 pub(crate) use _run as run;
@@ -77,6 +82,21 @@ impl Drop for Pushd {
     }
 }
 
+pub struct Pushenv {
+    _p: (),
+}
+
+pub fn pushenv(var: &str, value: &str) -> Pushenv {
+    Env::with(|env| env.pushenv(var.into(), value.into()));
+    Pushenv { _p: () }
+}
+
+impl Drop for Pushenv {
+    fn drop(&mut self) {
+        Env::with(|env| env.popenv())
+    }
+}
+
 pub fn rm_rf(path: impl AsRef<Path>) -> Result<()> {
     let path = path.as_ref();
     if !path.exists() {
@@ -90,15 +110,15 @@ pub fn rm_rf(path: impl AsRef<Path>) -> Result<()> {
 }
 
 #[doc(hidden)]
-pub fn run_process(cmd: String, echo: bool) -> Result<String> {
-    run_process_inner(&cmd, echo).with_context(|| format!("process `{}` failed", cmd))
+pub fn run_process(cmd: String, echo: bool, stdin: Option<&[u8]>) -> Result<String> {
+    run_process_inner(&cmd, echo, stdin).with_context(|| format!("process `{}` failed", cmd))
 }
 
 pub fn date_iso() -> Result<String> {
     run!("date --iso --utc")
 }
 
-fn run_process_inner(cmd: &str, echo: bool) -> Result<String> {
+fn run_process_inner(cmd: &str, echo: bool, stdin: Option<&[u8]>) -> Result<String> {
     let mut args = shelx(cmd);
     let binary = args.remove(0);
     let current_dir = Env::with(|it| it.cwd().to_path_buf());
@@ -107,12 +127,17 @@ fn run_process_inner(cmd: &str, echo: bool) -> Result<String> {
         println!("> {}", cmd)
     }
 
-    let output = Command::new(binary)
-        .args(args)
-        .current_dir(current_dir)
-        .stdin(Stdio::null())
-        .stderr(Stdio::inherit())
-        .output()?;
+    let mut command = Command::new(binary);
+    command.args(args).current_dir(current_dir).stderr(Stdio::inherit());
+    let output = match stdin {
+        None => command.stdin(Stdio::null()).output(),
+        Some(stdin) => {
+            command.stdin(Stdio::piped()).stdout(Stdio::piped());
+            let mut process = command.spawn()?;
+            process.stdin.take().unwrap().write_all(stdin)?;
+            process.wait_with_output()
+        }
+    }?;
     let stdout = String::from_utf8(output.stdout)?;
 
     if echo {
@@ -133,13 +158,15 @@ fn shelx(cmd: &str) -> Vec<String> {
 
 struct Env {
     pushd_stack: Vec<PathBuf>,
+    pushenv_stack: Vec<(OsString, Option<OsString>)>,
 }
 
 impl Env {
     fn with<F: FnOnce(&mut Env) -> T, T>(f: F) -> T {
         thread_local! {
             static ENV: RefCell<Env> = RefCell::new(Env {
-                pushd_stack: vec![env::current_dir().unwrap()]
+                pushd_stack: vec![env::current_dir().unwrap()],
+                pushenv_stack: vec![],
             });
         }
         ENV.with(|it| f(&mut *it.borrow_mut()))
@@ -154,6 +181,17 @@ impl Env {
         self.pushd_stack.pop().unwrap();
         env::set_current_dir(self.cwd()).unwrap();
     }
+    fn pushenv(&mut self, var: OsString, value: OsString) {
+        self.pushenv_stack.push((var.clone(), env::var_os(&var)));
+        env::set_var(var, value)
+    }
+    fn popenv(&mut self) {
+        let (var, value) = self.pushenv_stack.pop().unwrap();
+        match value {
+            None => env::remove_var(var),
+            Some(value) => env::set_var(var, value),
+        }
+    }
     fn cwd(&self) -> &Path {
         self.pushd_stack.last().unwrap()
     }