16 files changed, 366 insertions, 139 deletions

diff --git a/Cargo.lock b/Cargo.lock
index d6bd2e13e..908319f87 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -884,6 +884,7 @@ version = "0.1.0"
 name = "ra_assists"
 version = "0.1.0"
 dependencies = [
+ "either",
  "format-buf",
  "itertools 0.9.0",
  "join_to_string",
@@ -1045,6 +1046,7 @@ dependencies = [
 name = "ra_ide_db"
 version = "0.1.0"
 dependencies = [
+ "either",
  "fst",
  "log",
  "once_cell",
diff --git a/crates/ra_assists/Cargo.toml b/crates/ra_assists/Cargo.toml
index 707746ad5..a87f4052a 100644
--- a/crates/ra_assists/Cargo.toml
+++ b/crates/ra_assists/Cargo.toml
@@ -12,6 +12,7 @@ format-buf = "1.0.0"
 join_to_string = "0.1.3"
 rustc-hash = "1.1.0"
 itertools = "0.9.0"
+either = "1.5.3"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_text_edit = { path = "../ra_text_edit" }
diff --git a/crates/ra_assists/src/handlers/auto_import.rs b/crates/ra_assists/src/handlers/auto_import.rs
index bb280f633..99682e023 100644
--- a/crates/ra_assists/src/handlers/auto_import.rs
+++ b/crates/ra_assists/src/handlers/auto_import.rs
@@ -17,6 +17,7 @@ use crate::{
     utils::insert_use_statement,
     AssistId,
 };
+use either::Either;
 
 // Assist: auto_import
 //
@@ -58,6 +59,7 @@ pub(crate) fn auto_import(ctx: AssistCtx) -> Option<Assist> {
     group.finish()
 }
 
+#[derive(Debug)]
 struct AutoImportAssets {
     import_candidate: ImportCandidate,
     module_with_name_to_import: Module,
@@ -127,14 +129,14 @@ impl AutoImportAssets {
         ImportsLocator::new(db)
             .find_imports(&self.get_search_query())
             .into_iter()
-            .filter_map(|module_def| match &self.import_candidate {
+            .filter_map(|candidate| match &self.import_candidate {
                 ImportCandidate::TraitAssocItem(assoc_item_type, _) => {
-                    let located_assoc_item = match module_def {
-                        ModuleDef::Function(located_function) => located_function
+                    let located_assoc_item = match candidate {
+                        Either::Left(ModuleDef::Function(located_function)) => located_function
                             .as_assoc_item(db)
                             .map(|assoc| assoc.container(db))
                             .and_then(Self::assoc_to_trait),
-                        ModuleDef::Const(located_const) => located_const
+                        Either::Left(ModuleDef::Const(located_const)) => located_const
                             .as_assoc_item(db)
                             .map(|assoc| assoc.container(db))
                             .and_then(Self::assoc_to_trait),
@@ -153,10 +155,11 @@ impl AutoImportAssets {
                             |_, assoc| Self::assoc_to_trait(assoc.container(db)),
                         )
                         .map(ModuleDef::from)
+                        .map(Either::Left)
                 }
                 ImportCandidate::TraitMethod(function_callee, _) => {
                     let located_assoc_item =
-                        if let ModuleDef::Function(located_function) = module_def {
+                        if let Either::Left(ModuleDef::Function(located_function)) = candidate {
                             located_function
                                 .as_assoc_item(db)
                                 .map(|assoc| assoc.container(db))
@@ -179,10 +182,18 @@ impl AutoImportAssets {
                             },
                         )
                         .map(ModuleDef::from)
+                        .map(Either::Left)
+                }
+                _ => Some(candidate),
+            })
+            .filter_map(|candidate| match candidate {
+                Either::Left(module_def) => {
+                    self.module_with_name_to_import.find_use_path(db, module_def)
+                }
+                Either::Right(macro_def) => {
+                    self.module_with_name_to_import.find_use_path(db, macro_def)
                 }
-                _ => Some(module_def),
             })
-            .filter_map(|module_def| self.module_with_name_to_import.find_use_path(db, module_def))
             .filter(|use_path| !use_path.segments.is_empty())
             .take(20)
             .collect::<BTreeSet<_>>()
@@ -440,6 +451,30 @@ mod tests {
     }
 
     #[test]
+    fn macro_import() {
+        check_assist(
+            auto_import,
+            r"
+                    //- /lib.rs crate:crate_with_macro
+                    #[macro_export]
+                    macro_rules! foo {
+                        () => ()
+                    }
+
+                    //- /main.rs crate:main deps:crate_with_macro
+                    fn main() {
+                        foo<|>
+                    }",
+            r"use crate_with_macro::foo;
+
+fn main() {
+    foo<|>
+}
+",
+        );
+    }
+
+    #[test]
     fn auto_import_target() {
         check_assist_target(
             auto_import,
diff --git a/crates/ra_assists/src/handlers/fill_match_arms.rs b/crates/ra_assists/src/handlers/fill_match_arms.rs
index a7c315ca1..add82e5b1 100644
--- a/crates/ra_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ra_assists/src/handlers/fill_match_arms.rs
@@ -2,7 +2,7 @@
 
 use std::iter;
 
-use hir::{Adt, HasSource, Semantics};
+use hir::{Adt, HasSource, ModuleDef, Semantics};
 use itertools::Itertools;
 use ra_ide_db::RootDatabase;
 
@@ -154,7 +154,7 @@ fn resolve_tuple_of_enum_def(
 }
 
 fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> Option<ast::Pat> {
-    let path = crate::ast_transform::path_to_ast(module.find_use_path(db, var.into())?);
+    let path = crate::ast_transform::path_to_ast(module.find_use_path(db, ModuleDef::from(var))?);
 
     // FIXME: use HIR for this; it doesn't currently expose struct vs. tuple vs. unit variants though
     let pat: ast::Pat = match var.source(db).value.kind() {
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index b8704ea7d..bcc9b3f10 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -165,7 +165,6 @@ mod helpers {
 
     use ra_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt};
     use ra_ide_db::{symbol_index::SymbolsDatabase, RootDatabase};
-    use ra_syntax::TextRange;
     use test_utils::{add_cursor, assert_eq_text, extract_range_or_offset, RangeOrOffset};
 
     use crate::{AssistCtx, AssistHandler};
@@ -175,8 +174,7 @@ mod helpers {
         let (mut db, file_id) = RootDatabase::with_single_file(text);
         // FIXME: ideally, this should be done by the above `RootDatabase::with_single_file`,
         // but it looks like this might need specialization? :(
-        let local_roots = vec![db.file_source_root(file_id)];
-        db.set_local_roots(Arc::new(local_roots));
+        db.set_local_roots(Arc::new(vec![db.file_source_root(file_id)]));
         (db, file_id)
     }
 
@@ -206,11 +204,24 @@ mod helpers {
     }
 
     fn check(assist: AssistHandler, before: &str, expected: ExpectedResult) {
-        let (range_or_offset, before) = extract_range_or_offset(before);
-        let range: TextRange = range_or_offset.into();
+        let (text_without_caret, file_with_caret_id, range_or_offset, db) =
+            if before.contains("//-") {
+                let (mut db, position) = RootDatabase::with_position(before);
+                db.set_local_roots(Arc::new(vec![db.file_source_root(position.file_id)]));
+                (
+                    db.file_text(position.file_id).as_ref().to_owned(),
+                    position.file_id,
+                    RangeOrOffset::Offset(position.offset),
+                    db,
+                )
+            } else {
+                let (range_or_offset, text_without_caret) = extract_range_or_offset(before);
+                let (db, file_id) = with_single_file(&text_without_caret);
+                (text_without_caret, file_id, range_or_offset, db)
+            };
+
+        let frange = FileRange { file_id: file_with_caret_id, range: range_or_offset.into() };
 
-        let (db, file_id) = with_single_file(&before);
-        let frange = FileRange { file_id, range };
         let sema = Semantics::new(&db);
         let assist_ctx = AssistCtx::new(&sema, frange, true);
 
@@ -218,7 +229,7 @@ mod helpers {
             (Some(assist), ExpectedResult::After(after)) => {
                 let action = assist.0[0].action.clone().unwrap();
 
-                let mut actual = action.edit.apply(&before);
+                let mut actual = action.edit.apply(&text_without_caret);
                 match action.cursor_position {
                     None => {
                         if let RangeOrOffset::Offset(before_cursor_pos) = range_or_offset {
@@ -237,7 +248,7 @@ mod helpers {
             (Some(assist), ExpectedResult::Target(target)) => {
                 let action = assist.0[0].action.clone().unwrap();
                 let range = action.target.expect("expected target on action");
-                assert_eq_text!(&before[range], target);
+                assert_eq_text!(&text_without_caret[range], target);
             }
             (Some(_), ExpectedResult::NotApplicable) => panic!("assist should not be applicable!"),
             (None, ExpectedResult::After(_)) | (None, ExpectedResult::Target(_)) => {
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index e91abf6f5..c5cfd875f 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -33,7 +33,11 @@ use ra_syntax::{
 };
 use rustc_hash::FxHashSet;
 
-use crate::{db::HirDatabase, has_source::HasSource, CallableDef, HirDisplay, InFile, Name};
+use crate::{
+    db::{DefDatabase, HirDatabase},
+    has_source::HasSource,
+    CallableDef, HirDisplay, InFile, Name,
+};
 
 /// hir::Crate describes a single crate. It's the main interface with which
 /// a crate's dependencies interact. Mostly, it should be just a proxy for the
@@ -274,20 +278,10 @@ impl Module {
     /// this module, if possible.
     pub fn find_use_path(
         self,
-        db: &dyn HirDatabase,
-        item: ModuleDef,
+        db: &dyn DefDatabase,
+        item: impl Into<ItemInNs>,
     ) -> Option<hir_def::path::ModPath> {
-        // FIXME expose namespace choice
-        hir_def::find_path::find_path(db.upcast(), determine_item_namespace(item), self.into())
-    }
-}
-
-fn determine_item_namespace(module_def: ModuleDef) -> ItemInNs {
-    match module_def {
-        ModuleDef::Static(_) | ModuleDef::Const(_) | ModuleDef::Function(_) => {
-            ItemInNs::Values(module_def.into())
-        }
-        _ => ItemInNs::Types(module_def.into()),
+        hir_def::find_path::find_path(db, item.into(), self.into())
     }
 }
 
diff --git a/crates/ra_hir/src/from_id.rs b/crates/ra_hir/src/from_id.rs
index c179b13c6..62fb52e72 100644
--- a/crates/ra_hir/src/from_id.rs
+++ b/crates/ra_hir/src/from_id.rs
@@ -9,8 +9,8 @@ use hir_def::{
 };
 
 use crate::{
-    Adt, AssocItem, AttrDef, DefWithBody, EnumVariant, GenericDef, Local, ModuleDef, StructField,
-    VariantDef,
+    code_model::ItemInNs, Adt, AssocItem, AttrDef, DefWithBody, EnumVariant, GenericDef, Local,
+    MacroDef, ModuleDef, StructField, VariantDef,
 };
 
 macro_rules! from_id {
@@ -228,3 +228,20 @@ impl From<(DefWithBodyId, PatId)> for Local {
         Local { parent, pat_id }
     }
 }
+
+impl From<MacroDef> for ItemInNs {
+    fn from(macro_def: MacroDef) -> Self {
+        ItemInNs::Macros(macro_def.into())
+    }
+}
+
+impl From<ModuleDef> for ItemInNs {
+    fn from(module_def: ModuleDef) -> Self {
+        match module_def {
+            ModuleDef::Static(_) | ModuleDef::Const(_) | ModuleDef::Function(_) => {
+                ItemInNs::Values(module_def.into())
+            }
+            _ => ItemInNs::Types(module_def.into()),
+        }
+    }
+}
diff --git a/crates/ra_ide/src/completion/complete_postfix.rs b/crates/ra_ide/src/completion/complete_postfix.rs
index 0ba382165..0a00054b2 100644
--- a/crates/ra_ide/src/completion/complete_postfix.rs
+++ b/crates/ra_ide/src/completion/complete_postfix.rs
@@ -1,6 +1,9 @@
 //! FIXME: write short doc here
 
-use ra_syntax::{ast::AstNode, TextRange, TextUnit};
+use ra_syntax::{
+    ast::{self, AstNode},
+    TextRange, TextUnit,
+};
 use ra_text_edit::TextEdit;
 
 use crate::{
@@ -21,13 +24,8 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
         None => return,
     };
 
-    let receiver_text = if ctx.dot_receiver_is_ambiguous_float_literal {
-        let text = dot_receiver.syntax().text();
-        let without_dot = ..text.len() - TextUnit::of_char('.');
-        text.slice(without_dot).to_string()
-    } else {
-        dot_receiver.syntax().text().to_string()
-    };
+    let receiver_text =
+        get_receiver_text(dot_receiver, ctx.dot_receiver_is_ambiguous_float_literal);
 
     let receiver_ty = match ctx.sema.type_of_expr(&dot_receiver) {
         Some(it) => it,
@@ -35,10 +33,17 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
     };
 
     if receiver_ty.is_bool() || receiver_ty.is_unknown() {
-        postfix_snippet(ctx, "if", "if expr {}", &format!("if {} {{$0}}", receiver_text))
-            .add_to(acc);
         postfix_snippet(
             ctx,
+            &dot_receiver,
+            "if",
+            "if expr {}",
+            &format!("if {} {{$0}}", receiver_text),
+        )
+        .add_to(acc);
+        postfix_snippet(
+            ctx,
+            &dot_receiver,
             "while",
             "while expr {}",
             &format!("while {} {{\n$0\n}}", receiver_text),
@@ -46,28 +51,70 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
         .add_to(acc);
     }
 
-    postfix_snippet(ctx, "not", "!expr", &format!("!{}", receiver_text)).add_to(acc);
+    // !&&&42 is a compiler error, ergo process it before considering the references
+    postfix_snippet(ctx, &dot_receiver, "not", "!expr", &format!("!{}", receiver_text)).add_to(acc);
 
-    postfix_snippet(ctx, "ref", "&expr", &format!("&{}", receiver_text)).add_to(acc);
-    postfix_snippet(ctx, "refm", "&mut expr", &format!("&mut {}", receiver_text)).add_to(acc);
+    postfix_snippet(ctx, &dot_receiver, "ref", "&expr", &format!("&{}", receiver_text)).add_to(acc);
+    postfix_snippet(ctx, &dot_receiver, "refm", "&mut expr", &format!("&mut {}", receiver_text))
+        .add_to(acc);
+
+    // The rest of the postfix completions create an expression that moves an argument,
+    // so it's better to consider references now to avoid breaking the compilation
+    let dot_receiver = include_references(dot_receiver);
+    let receiver_text =
+        get_receiver_text(&dot_receiver, ctx.dot_receiver_is_ambiguous_float_literal);
 
     postfix_snippet(
         ctx,
+        &dot_receiver,
         "match",
         "match expr {}",
         &format!("match {} {{\n    ${{1:_}} => {{$0\\}},\n}}", receiver_text),
     )
     .add_to(acc);
 
-    postfix_snippet(ctx, "dbg", "dbg!(expr)", &format!("dbg!({})", receiver_text)).add_to(acc);
+    postfix_snippet(
+        ctx,
+        &dot_receiver,
+        "box",
+        "Box::new(expr)",
+        &format!("Box::new({})", receiver_text),
+    )
+    .add_to(acc);
 
-    postfix_snippet(ctx, "box", "Box::new(expr)", &format!("Box::new({})", receiver_text))
+    postfix_snippet(ctx, &dot_receiver, "dbg", "dbg!(expr)", &format!("dbg!({})", receiver_text))
         .add_to(acc);
 }
 
-fn postfix_snippet(ctx: &CompletionContext, label: &str, detail: &str, snippet: &str) -> Builder {
+fn get_receiver_text(receiver: &ast::Expr, receiver_is_ambiguous_float_literal: bool) -> String {
+    if receiver_is_ambiguous_float_literal {
+        let text = receiver.syntax().text();
+        let without_dot = ..text.len() - TextUnit::of_char('.');
+        text.slice(without_dot).to_string()
+    } else {
+        receiver.to_string()
+    }
+}
+
+fn include_references(initial_element: &ast::Expr) -> ast::Expr {
+    let mut resulting_element = initial_element.clone();
+    while let Some(parent_ref_element) =
+        resulting_element.syntax().parent().and_then(ast::RefExpr::cast)
+    {
+        resulting_element = ast::Expr::from(parent_ref_element);
+    }
+    resulting_element
+}
+
+fn postfix_snippet(
+    ctx: &CompletionContext,
+    receiver: &ast::Expr,
+    label: &str,
+    detail: &str,
+    snippet: &str,
+) -> Builder {
     let edit = {
-        let receiver_syntax = ctx.dot_receiver.as_ref().expect("no receiver available").syntax();
+        let receiver_syntax = receiver.syntax();
         let receiver_range = ctx.sema.original_range(receiver_syntax).range;
         let delete_range = TextRange::from_to(receiver_range.start(), ctx.source_range().end());
         TextEdit::replace(delete_range, snippet.to_string())
@@ -340,4 +387,63 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn postfix_completion_for_references() {
+        assert_debug_snapshot!(
+            do_postfix_completion(
+                r#"
+                fn main() {
+                    &&&&42.<|>
+                }
+                "#,
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "box",
+                source_range: [56; 56),
+                delete: [49; 56),
+                insert: "Box::new(&&&&42)",
+                detail: "Box::new(expr)",
+            },
+            CompletionItem {
+                label: "dbg",
+                source_range: [56; 56),
+                delete: [49; 56),
+                insert: "dbg!(&&&&42)",
+                detail: "dbg!(expr)",
+            },
+            CompletionItem {
+                label: "match",
+                source_range: [56; 56),
+                delete: [49; 56),
+                insert: "match &&&&42 {\n    ${1:_} => {$0\\},\n}",
+                detail: "match expr {}",
+            },
+            CompletionItem {
+                label: "not",
+                source_range: [56; 56),
+                delete: [53; 56),
+                insert: "!42",
+                detail: "!expr",
+            },
+            CompletionItem {
+                label: "ref",
+                source_range: [56; 56),
+                delete: [53; 56),
+                insert: "&42",
+                detail: "&expr",
+            },
+            CompletionItem {
+                label: "refm",
+                source_range: [56; 56),
+                delete: [53; 56),
+                insert: "&mut 42",
+                detail: "&mut expr",
+            },
+        ]
+        "###
+        );
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_record_literal.rs b/crates/ra_ide/src/completion/complete_record_literal.rs
index 83ed1d52c..e4e764f58 100644
--- a/crates/ra_ide/src/completion/complete_record_literal.rs
+++ b/crates/ra_ide/src/completion/complete_record_literal.rs
@@ -1,6 +1,7 @@
 //! FIXME: write short doc here
 
 use crate::completion::{CompletionContext, Completions};
+use ra_syntax::SmolStr;
 
 /// Complete fields in fields literals.
 pub(super) fn complete_record_literal(acc: &mut Completions, ctx: &CompletionContext) {
@@ -11,8 +12,24 @@ pub(super) fn complete_record_literal(acc: &mut Completions, ctx: &CompletionCon
         _ => return,
     };
 
+    let already_present_names: Vec<SmolStr> = ctx
+        .record_lit_syntax
+        .as_ref()
+        .and_then(|record_literal| record_literal.record_field_list())
+        .map(|field_list| field_list.fields())
+        .map(|fields| {
+            fields
+                .into_iter()
+                .filter_map(|field| field.name_ref())
+                .map(|name_ref| name_ref.text().clone())
+                .collect()
+        })
+        .unwrap_or_default();
+
     for (field, field_ty) in ty.variant_fields(ctx.db, variant) {
-        acc.add_field(ctx, field, &field_ty);
+        if !already_present_names.contains(&SmolStr::from(field.name(ctx.db).to_string())) {
+            acc.add_field(ctx, field, &field_ty);
+        }
     }
 }
 
@@ -178,4 +195,47 @@ mod tests {
         ]
         "###);
     }
+
+    #[test]
+    fn only_missing_fields_are_completed() {
+        let completions = complete(
+            r"
+            struct S {
+                foo1: u32,
+                foo2: u32,
+                bar: u32,
+                baz: u32,
+            }
+
+            fn main() {
+                let foo1 = 1;
+                let s = S {
+                    foo1,
+                    foo2: 5,
+                    <|>
+                }
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "bar",
+                source_range: [302; 302),
+                delete: [302; 302),
+                insert: "bar",
+                kind: Field,
+                detail: "u32",
+            },
+            CompletionItem {
+                label: "baz",
+                source_range: [302; 302),
+                delete: [302; 302),
+                insert: "baz",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###);
+    }
 }
diff --git a/crates/ra_ide_db/Cargo.toml b/crates/ra_ide_db/Cargo.toml
index de4f5bce0..c3921bd40 100644
--- a/crates/ra_ide_db/Cargo.toml
+++ b/crates/ra_ide_db/Cargo.toml
@@ -17,6 +17,7 @@ fst = { version = "0.4", default-features = false }
 rustc-hash = "1.1.0"
 superslice = "1.0.0"
 once_cell = "1.3.1"
+either = "1.5.3"
 
 ra_syntax = { path = "../ra_syntax" }
 ra_text_edit = { path = "../ra_text_edit" }
diff --git a/crates/ra_ide_db/src/imports_locator.rs b/crates/ra_ide_db/src/imports_locator.rs
index c96351982..bf0d8db60 100644
--- a/crates/ra_ide_db/src/imports_locator.rs
+++ b/crates/ra_ide_db/src/imports_locator.rs
@@ -1,7 +1,7 @@
 //! This module contains an import search funcionality that is provided to the ra_assists module.
 //! Later, this should be moved away to a separate crate that is accessible from the ra_assists module.
 
-use hir::{ModuleDef, Semantics};
+use hir::{MacroDef, ModuleDef, Semantics};
 use ra_prof::profile;
 use ra_syntax::{ast, AstNode, SyntaxKind::NAME};
 
@@ -10,6 +10,7 @@ use crate::{
     symbol_index::{self, FileSymbol, Query},
     RootDatabase,
 };
+use either::Either;
 
 pub struct ImportsLocator<'a> {
     sema: Semantics<'a, RootDatabase>,
@@ -20,7 +21,7 @@ impl<'a> ImportsLocator<'a> {
         Self { sema: Semantics::new(db) }
     }
 
-    pub fn find_imports(&mut self, name_to_import: &str) -> Vec<ModuleDef> {
+    pub fn find_imports(&mut self, name_to_import: &str) -> Vec<Either<ModuleDef, MacroDef>> {
         let _p = profile("search_for_imports");
         let db = self.sema.db;
 
@@ -43,7 +44,8 @@ impl<'a> ImportsLocator<'a> {
             .chain(lib_results.into_iter())
             .filter_map(|import_candidate| self.get_name_definition(&import_candidate))
             .filter_map(|name_definition_to_import| match name_definition_to_import {
-                Definition::ModuleDef(module_def) => Some(module_def),
+                Definition::ModuleDef(module_def) => Some(Either::Left(module_def)),
+                Definition::Macro(macro_def) => Some(Either::Right(macro_def)),
                 _ => None,
             })
             .collect()
diff --git a/docs/user/readme.adoc b/docs/user/readme.adoc
index 0dfc12b52..e00d14dfb 100644
--- a/docs/user/readme.adoc
+++ b/docs/user/readme.adoc
@@ -98,6 +98,16 @@ You'll need Cargo, nodejs and npm for this.
 
 Note that installing via `xtask install` does not work for VS Code Remote, instead you'll need to install the `.vsix` manually.
 
+==== Troubleshooting
+
+Here are some useful self-diagnostic commands:
+
+* **Rust Analyzer: Show RA Version** shows the version of `rust-analyzer` binary
+* **Rust Analyzer: Status** prints some statistics about the server, like the few latest LSP requests
+* To enable server-side logging, run with `env RUST_LOG=info` and see `Output > Rust Analyzer Language Server` in VS Code's panel.
+* To log all LSP requests, add `"rust-analyzer.trace.server": "verbose"` to the settings and look for `Server Trace` in the panel.
+* To enable client-side logging, add `"rust-analyzer.trace.extension": true` to the settings and open the `Console` tab of VS Code developer tools.
+
 === Language Server Binary
 
 Other editors generally require `rust-analyzer` binary to be in `$PATH`.
diff --git a/editors/code/package.json b/editors/code/package.json
index eb5748515..1d113ebb6 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -73,10 +73,18 @@
                         "type": "string"
                     },
                     "args": {
-                        "type": "array"
+                        "type": "array",
+                        "items": {
+                            "type": "string"
+                        }
                     },
                     "env": {
-                        "type": "object"
+                        "type": "object",
+                        "patternProperties": {
+                            ".+": {
+                                "type": "string"
+                            }
+                        }
                     }
                 }
             }
diff --git a/editors/code/src/client.ts b/editors/code/src/client.ts
index 08d821dd0..82ca749f3 100644
--- a/editors/code/src/client.ts
+++ b/editors/code/src/client.ts
@@ -99,8 +99,10 @@ export async function createClient(config: Config, serverPath: string): Promise<
     // Note that while the CallHierarchyFeature is stable the LSP protocol is not.
     res.registerFeature(new CallHierarchyFeature(res));
 
-    if (config.highlightingSemanticTokens) {
-        res.registerFeature(new SemanticTokensFeature(res));
+    if (config.package.enableProposedApi) {
+        if (config.highlightingSemanticTokens) {
+            res.registerFeature(new SemanticTokensFeature(res));
+        }
     }
 
     return res;
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index be5296fcf..7668c20b7 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -1,29 +1,10 @@
 import * as vscode from 'vscode';
 import { log } from "./util";
 
-export interface InlayHintOptions {
-    typeHints: boolean;
-    parameterHints: boolean;
-    maxLength: number | null;
-}
-
-export interface CargoWatchOptions {
-    enable: boolean;
-    arguments: string[];
-    command: string;
-    allTargets: boolean;
-}
-
-export interface CargoFeatures {
-    noDefaultFeatures: boolean;
-    allFeatures: boolean;
-    features: string[];
-    loadOutDirsFromCheck: boolean;
-}
-
 export type UpdatesChannel = "stable" | "nightly";
 
 export const NIGHTLY_TAG = "nightly";
+
 export class Config {
     readonly extensionId = "matklad.rust-analyzer";
 
@@ -38,37 +19,30 @@ export class Config {
     ]
         .map(opt => `${this.rootSection}.${opt}`);
 
-    readonly packageJsonVersion: string = vscode
-        .extensions
-        .getExtension(this.extensionId)!
-        .packageJSON
-        .version;
-
-    readonly releaseTag: string | undefined = vscode
-        .extensions
-        .getExtension(this.extensionId)!
-        .packageJSON
-        .releaseTag ?? undefined;
+    readonly package: {
+        version: string;
+        releaseTag: string | undefined;
+        enableProposedApi: boolean | undefined;
+    } = vscode.extensions.getExtension(this.extensionId)!.packageJSON;
 
-    private cfg!: vscode.WorkspaceConfiguration;
+    readonly globalStoragePath: string;
 
-    constructor(private readonly ctx: vscode.ExtensionContext) {
-        vscode.workspace.onDidChangeConfiguration(this.onConfigChange, this, ctx.subscriptions);
-        this.refreshConfig();
+    constructor(ctx: vscode.ExtensionContext) {
+        this.globalStoragePath = ctx.globalStoragePath;
+        vscode.workspace.onDidChangeConfiguration(this.onDidChangeConfiguration, this, ctx.subscriptions);
+        this.refreshLogging();
     }
 
-    private refreshConfig() {
-        this.cfg = vscode.workspace.getConfiguration(this.rootSection);
-        const enableLogging = this.cfg.get("trace.extension") as boolean;
-        log.setEnabled(enableLogging);
+    private refreshLogging() {
+        log.setEnabled(this.traceExtension);
         log.debug(
-            "Extension version:", this.packageJsonVersion,
+            "Extension version:", this.package.version,
             "using configuration:", this.cfg
         );
     }
 
-    private async onConfigChange(event: vscode.ConfigurationChangeEvent) {
-        this.refreshConfig();
+    private async onDidChangeConfiguration(event: vscode.ConfigurationChangeEvent) {
+        this.refreshLogging();
 
         const requiresReloadOpt = this.requiresReloadOpts.find(
             opt => event.affectsConfiguration(opt)
@@ -86,49 +60,53 @@ export class Config {
         }
     }
 
-    get globalStoragePath(): string { return this.ctx.globalStoragePath; }
-
     // We don't do runtime config validation here for simplicity. More on stackoverflow:
     // https://stackoverflow.com/questions/60135780/what-is-the-best-way-to-type-check-the-configuration-for-vscode-extension
 
-    get serverPath() { return this.cfg.get("serverPath") as null | string; }
-    get channel() { return this.cfg.get<"stable" | "nightly">("updates.channel")!; }
-    get askBeforeDownload() { return this.cfg.get("updates.askBeforeDownload") as boolean; }
-    get highlightingSemanticTokens() { return this.cfg.get("highlighting.semanticTokens") as boolean; }
-    get highlightingOn() { return this.cfg.get("highlightingOn") as boolean; }
-    get rainbowHighlightingOn() { return this.cfg.get("rainbowHighlightingOn") as boolean; }
-    get lruCapacity() { return this.cfg.get("lruCapacity") as null | number; }
-    get inlayHints(): InlayHintOptions {
+    private get cfg(): vscode.WorkspaceConfiguration {
+        return vscode.workspace.getConfiguration(this.rootSection);
+    }
+
+    get serverPath() { return this.cfg.get<null | string>("serverPath")!; }
+    get channel() { return this.cfg.get<UpdatesChannel>("updates.channel")!; }
+    get askBeforeDownload() { return this.cfg.get<boolean>("updates.askBeforeDownload")!; }
+    get highlightingSemanticTokens() { return this.cfg.get<boolean>("highlighting.semanticTokens")!; }
+    get highlightingOn() { return this.cfg.get<boolean>("highlightingOn")!; }
+    get rainbowHighlightingOn() { return this.cfg.get<boolean>("rainbowHighlightingOn")!; }
+    get lruCapacity() { return this.cfg.get<null | number>("lruCapacity")!; }
+    get excludeGlobs() { return this.cfg.get<string[]>("excludeGlobs")!; }
+    get useClientWatching() { return this.cfg.get<boolean>("useClientWatching")!; }
+    get featureFlags() { return this.cfg.get<Record<string, boolean>>("featureFlags")!; }
+    get rustfmtArgs() { return this.cfg.get<string[]>("rustfmtArgs")!; }
+    get loadOutDirsFromCheck() { return this.cfg.get<boolean>("loadOutDirsFromCheck")!; }
+    get traceExtension() { return this.cfg.get<boolean>("trace.extension")!; }
+
+    // for internal use
+    get withSysroot() { return this.cfg.get<boolean>("withSysroot", true)!; }
+
+    get inlayHints() {
         return {
-            typeHints: this.cfg.get("inlayHints.typeHints") as boolean,
-            parameterHints: this.cfg.get("inlayHints.parameterHints") as boolean,
-            maxLength: this.cfg.get("inlayHints.maxLength") as null | number,
+            typeHints: this.cfg.get<boolean>("inlayHints.typeHints")!,
+            parameterHints: this.cfg.get<boolean>("inlayHints.parameterHints")!,
+            maxLength: this.cfg.get<null | number>("inlayHints.maxLength")!,
         };
     }
-    get excludeGlobs() { return this.cfg.get("excludeGlobs") as string[]; }
-    get useClientWatching() { return this.cfg.get("useClientWatching") as boolean; }
-    get featureFlags() { return this.cfg.get("featureFlags") as Record<string, boolean>; }
-    get rustfmtArgs() { return this.cfg.get("rustfmtArgs") as string[]; }
-    get loadOutDirsFromCheck() { return this.cfg.get("loadOutDirsFromCheck") as boolean; }
 
-    get cargoWatchOptions(): CargoWatchOptions {
+    get cargoWatchOptions() {
         return {
-            enable: this.cfg.get("cargo-watch.enable") as boolean,
-            arguments: this.cfg.get("cargo-watch.arguments") as string[],
-            allTargets: this.cfg.get("cargo-watch.allTargets") as boolean,
-            command: this.cfg.get("cargo-watch.command") as string,
+            enable: this.cfg.get<boolean>("cargo-watch.enable")!,
+            arguments: this.cfg.get<string[]>("cargo-watch.arguments")!,
+            allTargets: this.cfg.get<boolean>("cargo-watch.allTargets")!,
+            command: this.cfg.get<string>("cargo-watch.command")!,
         };
     }
 
-    get cargoFeatures(): CargoFeatures {
+    get cargoFeatures() {
         return {
-            noDefaultFeatures: this.cfg.get("cargoFeatures.noDefaultFeatures") as boolean,
-            allFeatures: this.cfg.get("cargoFeatures.allFeatures") as boolean,
-            features: this.cfg.get("cargoFeatures.features") as string[],
-            loadOutDirsFromCheck: this.cfg.get("cargoFeatures.loadOutDirsFromCheck") as boolean,
+            noDefaultFeatures: this.cfg.get<boolean>("cargoFeatures.noDefaultFeatures")!,
+            allFeatures: this.cfg.get<boolean>("cargoFeatures.allFeatures")!,
+            features: this.cfg.get<string[]>("cargoFeatures.features")!,
+            loadOutDirsFromCheck: this.cfg.get<boolean>("cargoFeatures.loadOutDirsFromCheck")!,
         };
     }
-
-    // for internal use
-    get withSysroot() { return this.cfg.get("withSysroot", true) as boolean; }
 }
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 5d2da9a76..7b7c19dfc 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -110,9 +110,9 @@ async function bootstrap(config: Config, state: PersistentState): Promise<string
 }
 
 async function bootstrapExtension(config: Config, state: PersistentState): Promise<void> {
-    if (config.releaseTag === undefined) return;
+    if (config.package.releaseTag === undefined) return;
     if (config.channel === "stable") {
-        if (config.releaseTag === NIGHTLY_TAG) {
+        if (config.package.releaseTag === NIGHTLY_TAG) {
             vscode.window.showWarningMessage(`You are running a nightly version of rust-analyzer extension.
 To switch to stable, uninstall the extension and re-install it from the marketplace`);
         }
@@ -185,7 +185,7 @@ async function getServer(config: Config, state: PersistentState): Promise<string
         }
         return explicitPath;
     };
-    if (config.releaseTag === undefined) return "rust-analyzer";
+    if (config.package.releaseTag === undefined) return "rust-analyzer";
 
     let binaryName: string | undefined = undefined;
     if (process.arch === "x64" || process.arch === "x32") {
@@ -211,21 +211,21 @@ async function getServer(config: Config, state: PersistentState): Promise<string
         await state.updateServerVersion(undefined);
     }
 
-    if (state.serverVersion === config.packageJsonVersion) return dest;
+    if (state.serverVersion === config.package.version) return dest;
 
     if (config.askBeforeDownload) {
         const userResponse = await vscode.window.showInformationMessage(
-            `Language server version ${config.packageJsonVersion} for rust-analyzer is not installed.`,
+            `Language server version ${config.package.version} for rust-analyzer is not installed.`,
             "Download now"
         );
         if (userResponse !== "Download now") return dest;
     }
 
-    const release = await fetchRelease(config.releaseTag);
+    const release = await fetchRelease(config.package.releaseTag);
     const artifact = release.assets.find(artifact => artifact.name === binaryName);
     assert(!!artifact, `Bad release: ${JSON.stringify(release)}`);
 
     await download(artifact.browser_download_url, dest, "Downloading rust-analyzer server", { mode: 0o755 });
-    await state.updateServerVersion(config.packageJsonVersion);
+    await state.updateServerVersion(config.package.version);
     return dest;
 }