34 files changed, 644 insertions, 206 deletions

diff --git a/crates/assists/src/handlers/remove_unused_param.rs b/crates/assists/src/handlers/remove_unused_param.rs
index 5fccca54b..1ff5e92b0 100644
--- a/crates/assists/src/handlers/remove_unused_param.rs
+++ b/crates/assists/src/handlers/remove_unused_param.rs
@@ -73,7 +73,8 @@ fn process_usage(
     let source_file = ctx.sema.parse(usage.file_range.file_id);
     let call_expr: ast::CallExpr =
         find_node_at_range(source_file.syntax(), usage.file_range.range)?;
-    if call_expr.expr()?.syntax().text_range() != usage.file_range.range {
+    let call_expr_range = call_expr.expr()?.syntax().text_range();
+    if !call_expr_range.contains_range(usage.file_range.range) {
         return None;
     }
     let arg = call_expr.arg_list()?.args().nth(arg_to_remove)?;
@@ -118,6 +119,53 @@ fn b() { foo(9, ) }
     }
 
     #[test]
+    fn remove_unused_qualified_call() {
+        check_assist(
+            remove_unused_param,
+            r#"
+mod bar { pub fn foo(x: i32, <|>y: i32) { x; } }
+fn b() { bar::foo(9, 2) }
+"#,
+            r#"
+mod bar { pub fn foo(x: i32) { x; } }
+fn b() { bar::foo(9) }
+"#,
+        );
+    }
+
+    #[test]
+    fn remove_unused_turbofished_func() {
+        check_assist(
+            remove_unused_param,
+            r#"
+pub fn foo<T>(x: T, <|>y: i32) { x; }
+fn b() { foo::<i32>(9, 2) }
+"#,
+            r#"
+pub fn foo<T>(x: T) { x; }
+fn b() { foo::<i32>(9) }
+"#,
+        );
+    }
+
+    #[test]
+    fn remove_unused_generic_unused_param_func() {
+        check_assist(
+            remove_unused_param,
+            r#"
+pub fn foo<T>(x: i32, <|>y: T) { x; }
+fn b() { foo::<i32>(9, 2) }
+fn b2() { foo(9, 2) }
+"#,
+            r#"
+pub fn foo<T>(x: i32) { x; }
+fn b() { foo::<i32>(9) }
+fn b2() { foo(9) }
+"#,
+        );
+    }
+
+    #[test]
     fn keep_used() {
         mark::check!(keep_used);
         check_assist_not_applicable(
@@ -128,4 +176,37 @@ fn main() { foo(9, 2) }
 "#,
         );
     }
+
+    #[test]
+    fn remove_across_files() {
+        check_assist(
+            remove_unused_param,
+            r#"
+//- /main.rs
+fn foo(x: i32, <|>y: i32) { x; }
+
+mod foo;
+
+//- /foo.rs
+use super::foo;
+
+fn bar() {
+    let _ = foo(1, 2);
+}
+"#,
+            r#"
+//- /main.rs
+fn foo(x: i32) { x; }
+
+mod foo;
+
+//- /foo.rs
+use super::foo;
+
+fn bar() {
+    let _ = foo(1);
+}
+"#,
+        )
+    }
 }
diff --git a/crates/assists/src/utils/insert_use.rs b/crates/assists/src/utils/insert_use.rs
index 84a0dffdd..af3fc96b6 100644
--- a/crates/assists/src/utils/insert_use.rs
+++ b/crates/assists/src/utils/insert_use.rs
@@ -9,7 +9,7 @@ use syntax::{
         edit::{AstNodeEdit, IndentLevel},
         make, AstNode, PathSegmentKind, VisibilityOwner,
     },
-    InsertPosition, SyntaxElement, SyntaxNode,
+    AstToken, InsertPosition, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken,
 };
 use test_utils::mark;
 
@@ -63,27 +63,30 @@ impl ImportScope {
         }
     }
 
-    fn insert_pos_after_inner_attribute(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
-        // check if the scope has inner attributes, we dont want to insert in front of them
-        match self
-            .as_syntax_node()
-            .children()
-            // no flat_map here cause we want to short circuit the iterator
-            .map(ast::Attr::cast)
-            .take_while(|attr| {
-                attr.as_ref().map(|attr| attr.kind() == ast::AttrKind::Inner).unwrap_or(false)
+    fn insert_pos_after_last_inner_element(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
+        self.as_syntax_node()
+            .children_with_tokens()
+            .filter(|child| match child {
+                NodeOrToken::Node(node) => is_inner_attribute(node.clone()),
+                NodeOrToken::Token(token) => is_inner_comment(token.clone()),
             })
             .last()
-            .flatten()
-        {
-            Some(attr) => {
-                (InsertPosition::After(attr.syntax().clone().into()), AddBlankLine::BeforeTwice)
-            }
-            None => self.first_insert_pos(),
-        }
+            .map(|last_inner_element| {
+                (InsertPosition::After(last_inner_element.into()), AddBlankLine::BeforeTwice)
+            })
+            .unwrap_or_else(|| self.first_insert_pos())
     }
 }
 
+fn is_inner_attribute(node: SyntaxNode) -> bool {
+    ast::Attr::cast(node).map(|attr| attr.kind()) == Some(ast::AttrKind::Inner)
+}
+
+fn is_inner_comment(token: SyntaxToken) -> bool {
+    ast::Comment::cast(token).and_then(|comment| comment.kind().doc)
+        == Some(ast::CommentPlacement::Inner)
+}
+
 /// Insert an import path into the given file/node. A `merge` value of none indicates that no import merging is allowed to occur.
 pub(crate) fn insert_use<'a>(
     scope: &ImportScope,
@@ -558,7 +561,7 @@ fn find_insert_position(
                             (InsertPosition::After(node.into()), AddBlankLine::BeforeTwice)
                         }
                         // there are no imports in this file at all
-                        None => scope.insert_pos_after_inner_attribute(),
+                        None => scope.insert_pos_after_last_inner_element(),
                     },
                 }
             }
@@ -830,12 +833,67 @@ use foo::bar;",
             "foo::bar",
             r"#![allow(unused_imports)]
 
+#![no_std]
 fn main() {}",
             r"#![allow(unused_imports)]
 
-use foo::bar;
+#![no_std]
 
+use foo::bar;
 fn main() {}",
+        );
+    }
+
+    #[test]
+    fn inserts_after_single_line_inner_comments() {
+        check_none(
+            "foo::bar::Baz",
+            "//! Single line inner comments do not allow any code before them.",
+            r#"//! Single line inner comments do not allow any code before them.
+
+use foo::bar::Baz;"#,
+        );
+    }
+
+    #[test]
+    fn inserts_after_multiline_inner_comments() {
+        check_none(
+            "foo::bar::Baz",
+            r#"/*! Multiline inner comments do not allow any code before them. */
+
+/*! Still an inner comment, cannot place any code before. */
+fn main() {}"#,
+            r#"/*! Multiline inner comments do not allow any code before them. */
+
+/*! Still an inner comment, cannot place any code before. */
+
+use foo::bar::Baz;
+fn main() {}"#,
+        )
+    }
+
+    #[test]
+    fn inserts_after_all_inner_items() {
+        check_none(
+            "foo::bar::Baz",
+            r#"#![allow(unused_imports)]
+/*! Multiline line comment 2 */
+
+
+//! Single line comment 1
+#![no_std]
+//! Single line comment 2
+fn main() {}"#,
+            r#"#![allow(unused_imports)]
+/*! Multiline line comment 2 */
+
+
+//! Single line comment 1
+#![no_std]
+//! Single line comment 2
+
+use foo::bar::Baz;
+fn main() {}"#,
         )
     }
 
diff --git a/crates/hir_ty/Cargo.toml b/crates/hir_ty/Cargo.toml
index fdc65a5c3..cf5c38a23 100644
--- a/crates/hir_ty/Cargo.toml
+++ b/crates/hir_ty/Cargo.toml
@@ -35,3 +35,4 @@ expect-test = "1.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.2", default-features = false, features = ["env-filter", "registry"] }
 tracing-tree = { version = "0.1.4" }
+once_cell = { version = "1.5.0", features = ["unstable"] }
diff --git a/crates/hir_ty/src/tests.rs b/crates/hir_ty/src/tests.rs
index 104ef334c..0a400cb70 100644
--- a/crates/hir_ty/src/tests.rs
+++ b/crates/hir_ty/src/tests.rs
@@ -22,7 +22,8 @@ use hir_def::{
     AssocItemId, DefWithBodyId, LocalModuleId, Lookup, ModuleDefId,
 };
 use hir_expand::{db::AstDatabase, InFile};
-use stdx::{format_to, RacyFlag};
+use once_cell::race::OnceBool;
+use stdx::format_to;
 use syntax::{
     algo,
     ast::{self, AstNode},
@@ -40,8 +41,8 @@ use crate::{
 // `env UPDATE_EXPECT=1 cargo test -p hir_ty` to update the snapshots.
 
 fn setup_tracing() -> Option<tracing::subscriber::DefaultGuard> {
-    static ENABLE: RacyFlag = RacyFlag::new();
-    if !ENABLE.get(|| env::var("CHALK_DEBUG").is_ok()) {
+    static ENABLE: OnceBool = OnceBool::new();
+    if !ENABLE.get_or_init(|| env::var("CHALK_DEBUG").is_ok()) {
         return None;
     }
 
diff --git a/crates/ide/src/syntax_highlighting.rs b/crates/ide/src/syntax_highlighting.rs
index 37ab7a8f6..1ed77b40b 100644
--- a/crates/ide/src/syntax_highlighting.rs
+++ b/crates/ide/src/syntax_highlighting.rs
@@ -6,7 +6,7 @@ pub(crate) mod tags;
 #[cfg(test)]
 mod tests;
 
-use hir::{Local, Name, Semantics, VariantDef};
+use hir::{AsAssocItem, Local, Name, Semantics, VariantDef};
 use ide_db::{
     defs::{Definition, NameClass, NameRefClass},
     RootDatabase,
@@ -746,6 +746,9 @@ fn highlight_def(db: &RootDatabase, def: Definition) -> Highlight {
                 if func.is_unsafe(db) {
                     h |= HighlightModifier::Unsafe;
                 }
+                if func.as_assoc_item(db).is_some() && func.self_param(db).is_none() {
+                    h |= HighlightModifier::Static;
+                }
                 return h;
             }
             hir::ModuleDef::Adt(hir::Adt::Struct(_)) => HighlightTag::Struct,
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
index e8f78ad52..65e0671a5 100644
--- a/crates/ide/src/syntax_highlighting/tags.rs
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -65,6 +65,8 @@ pub enum HighlightModifier {
     Consuming,
     Unsafe,
     Callable,
+    /// Used for associated functions
+    Static,
 }
 
 impl HighlightTag {
@@ -124,6 +126,7 @@ impl HighlightModifier {
         HighlightModifier::Consuming,
         HighlightModifier::Unsafe,
         HighlightModifier::Callable,
+        HighlightModifier::Static,
     ];
 
     fn as_str(self) -> &'static str {
@@ -137,6 +140,7 @@ impl HighlightModifier {
             HighlightModifier::Consuming => "consuming",
             HighlightModifier::Unsafe => "unsafe",
             HighlightModifier::Callable => "callable",
+            HighlightModifier::Static => "static",
         }
     }
 
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_assoc_functions.html b/crates/ide/src/syntax_highlighting/test_data/highlight_assoc_functions.html
new file mode 100644
index 000000000..cd80d72b7
--- /dev/null
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_assoc_functions.html
@@ -0,0 +1,56 @@
+
+<style>
+body                { margin: 0; }
+pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padding: 0.4em; }
+
+.lifetime           { color: #DFAF8F; font-style: italic; }
+.comment            { color: #7F9F7F; }
+.documentation      { color: #629755; }
+.injected           { opacity: 0.65 ; }
+.struct, .enum      { color: #7CB8BB; }
+.enum_variant       { color: #BDE0F3; }
+.string_literal     { color: #CC9393; }
+.field              { color: #94BFF3; }
+.function           { color: #93E0E3; }
+.function.unsafe    { color: #BC8383; }
+.operator.unsafe    { color: #BC8383; }
+.parameter          { color: #94BFF3; }
+.text               { color: #DCDCCC; }
+.type               { color: #7CB8BB; }
+.builtin_type       { color: #8CD0D3; }
+.type_param         { color: #DFAF8F; }
+.attribute          { color: #94BFF3; }
+.numeric_literal    { color: #BFEBBF; }
+.bool_literal       { color: #BFE6EB; }
+.macro              { color: #94BFF3; }
+.module             { color: #AFD8AF; }
+.value_param        { color: #DCDCCC; }
+.variable           { color: #DCDCCC; }
+.format_specifier   { color: #CC696B; }
+.mutable            { text-decoration: underline; }
+.escape_sequence    { color: #94BFF3; }
+.keyword            { color: #F0DFAF; font-weight: bold; }
+.keyword.unsafe     { color: #BC8383; font-weight: bold; }
+.control            { font-style: italic; }
+
+.unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
+</style>
+<pre><code><span class="keyword">fn</span> <span class="function declaration">not_static</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">struct</span> <span class="struct declaration">foo</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="struct">foo</span> <span class="punctuation">{</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration static">is_static</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">is_not_static</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">trait</span> <span class="trait declaration">t</span> <span class="punctuation">{</span>
+    <span class="keyword">fn</span> <span class="function declaration static">t_is_static</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+    <span class="keyword">fn</span> <span class="function declaration">t_is_not_static</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">impl</span> <span class="trait">t</span> <span class="keyword">for</span> <span class="struct">foo</span> <span class="punctuation">{</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration static">is_static</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+    <span class="keyword">pub</span> <span class="keyword">fn</span> <span class="function declaration">is_not_static</span><span class="punctuation">(</span><span class="operator">&</span><span class="self_keyword">self</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+<span class="punctuation">}</span>
+        </code></pre>
\ No newline at end of file
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html b/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
index f44fe457d..6be88f856 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
@@ -53,7 +53,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="comment documentation">/// #</span><span class="generic injected"> </span><span class="attribute injected">#</span><span class="attribute injected">!</span><span class="attribute injected">[</span><span class="function attribute injected">allow</span><span class="punctuation injected">(</span><span class="attribute injected">unused_mut</span><span class="punctuation injected">)</span><span class="attribute injected">]</span>
     <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="generic injected"> </span><span class="keyword injected">mut</span><span class="generic injected"> </span><span class="variable declaration injected mutable">foo</span><span class="punctuation injected">:</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="generic injected"> </span><span class="operator injected">=</span><span class="generic injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="function injected">new</span><span class="punctuation injected">(</span><span class="punctuation injected">)</span><span class="punctuation injected">;</span><span class="punctuation injected">
 </span>    <span class="comment documentation">/// ```</span>
-    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration">new</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
+    <span class="keyword">pub</span> <span class="keyword">const</span> <span class="keyword">fn</span> <span class="function declaration static">new</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="struct">Foo</span> <span class="punctuation">{</span>
         <span class="struct">Foo</span> <span class="punctuation">{</span> <span class="field">bar</span><span class="punctuation">:</span> <span class="bool_literal">true</span> <span class="punctuation">}</span>
     <span class="punctuation">}</span>
 
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlight_injection.html b/crates/ide/src/syntax_highlighting/test_data/highlight_injection.html
index 18addd00d..57c178916 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_injection.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_injection.html
@@ -40,7 +40,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 <span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
     <span class="function">fixture</span><span class="punctuation">(</span><span class="string_literal">r#"</span>
         <span class="keyword">trait</span> <span class="trait declaration">Foo</span> <span class="punctuation">{</span>
-            <span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
+            <span class="keyword">fn</span> <span class="function declaration static">foo</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
                 <span class="macro">println!</span><span class="punctuation">(</span><span class="string_literal">"2 + 2 = {}"</span><span class="punctuation">,</span> <span class="numeric_literal">4</span><span class="punctuation">)</span><span class="punctuation">;</span>
             <span class="punctuation">}</span>
         <span class="punctuation">}</span><span class="string_literal">"#</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index 2b667b0d4..5c22e2fce 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -513,6 +513,34 @@ fn test_extern_crate() {
     );
 }
 
+#[test]
+fn test_associated_function() {
+    check_highlighting(
+        r#"
+fn not_static() {}
+
+struct foo {}
+
+impl foo {
+    pub fn is_static() {}
+    pub fn is_not_static(&self) {}
+}
+
+trait t {
+    fn t_is_static() {}
+    fn t_is_not_static(&self) {}
+}
+
+impl t for foo {
+    pub fn is_static() {}
+    pub fn is_not_static(&self) {}
+}
+        "#,
+        expect_file!["./test_data/highlight_assoc_functions.html"],
+        false,
+    )
+}
+
 /// Highlights the code given by the `ra_fixture` argument, renders the
 /// result as HTML, and compares it with the HTML file given as `snapshot`.
 /// Note that the `snapshot` file is overwritten by the rendered HTML.
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index ff1ae9575..9a8870053 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -16,8 +16,6 @@ use serde_json::json;
 use crate::semantic_tokens;
 
 pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabilities {
-    let code_action_provider = code_action_capabilities(client_caps);
-
     ServerCapabilities {
         text_document_sync: Some(TextDocumentSyncCapability::Options(TextDocumentSyncOptions {
             open_close: Some(true),
@@ -49,7 +47,7 @@ pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabiliti
         document_highlight_provider: Some(OneOf::Left(true)),
         document_symbol_provider: Some(OneOf::Left(true)),
         workspace_symbol_provider: Some(OneOf::Left(true)),
-        code_action_provider: Some(code_action_provider),
+        code_action_provider: Some(code_action_capabilities(client_caps)),
         code_lens_provider: Some(CodeLensOptions { resolve_provider: Some(true) }),
         document_formatting_provider: Some(OneOf::Left(true)),
         document_range_formatting_provider: None,
@@ -113,7 +111,7 @@ fn code_action_capabilities(client_caps: &ClientCapabilities) -> CodeActionProvi
                     CodeActionKind::REFACTOR_INLINE,
                     CodeActionKind::REFACTOR_REWRITE,
                 ]),
-                resolve_provider: None,
+                resolve_provider: Some(true),
                 work_done_progress_options: Default::default(),
             })
         })
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 2ed6a0d82..b4c738272 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -144,7 +144,7 @@ pub struct ClientCapsConfig {
     pub code_action_literals: bool,
     pub work_done_progress: bool,
     pub code_action_group: bool,
-    pub resolve_code_action: bool,
+    pub code_action_resolve: bool,
     pub hover_actions: bool,
     pub status_notification: bool,
     pub signature_help_label_offsets: bool,
@@ -383,6 +383,17 @@ impl Config {
                     }
                 }
             }
+
+            if let Some(code_action) = &doc_caps.code_action {
+                match (code_action.data_support, &code_action.resolve_support) {
+                    (Some(true), Some(resolve_support)) => {
+                        if resolve_support.properties.iter().any(|it| it == "edit") {
+                            self.client_caps.code_action_resolve = true;
+                        }
+                    }
+                    _ => (),
+                }
+            }
         }
 
         if let Some(window_caps) = caps.window.as_ref() {
@@ -400,7 +411,6 @@ impl Config {
             self.assist.allow_snippets(snippet_text_edit);
 
             self.client_caps.code_action_group = get_bool("codeActionGroup");
-            self.client_caps.resolve_code_action = get_bool("resolveCodeAction");
             self.client_caps.hover_actions = get_bool("hoverActions");
             self.client_caps.status_notification = get_bool("statusNotification");
         }
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/clippy_pass_by_ref.txt b/crates/rust-analyzer/src/diagnostics/test_data/clippy_pass_by_ref.txt
index 58d47d32a..5b2e5187a 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/clippy_pass_by_ref.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/clippy_pass_by_ref.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/compiler/mir/tagset.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/compiler/mir/tagset.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -29,7 +36,14 @@
                 [
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/compiler/lib.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/compiler/lib.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 0,
@@ -45,7 +59,14 @@
                     },
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/compiler/mir/tagset.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/compiler/mir/tagset.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 41,
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/handles_macro_location.txt b/crates/rust-analyzer/src/diagnostics/test_data/handles_macro_location.txt
index 6aa26bf63..116f0ff73 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/handles_macro_location.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/handles_macro_location.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/src/main.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/src/main.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/macro_compiler_error.txt b/crates/rust-analyzer/src/diagnostics/test_data/macro_compiler_error.txt
index 7aaffaba2..bbec6a796 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/macro_compiler_error.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/macro_compiler_error.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/crates/hir_def/src/data.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/crates/hir_def/src/data.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -25,7 +32,14 @@
                 [
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/crates/hir_def/src/path.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/crates/hir_def/src/path.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 264,
@@ -47,7 +61,14 @@
         fixes: [],
     },
     MappedRustDiagnostic {
-        url: "file:///test/crates/hir_def/src/path.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/crates/hir_def/src/path.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -72,7 +93,14 @@
                 [
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/crates/hir_def/src/data.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/crates/hir_def/src/data.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 79,
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_incompatible_type_for_trait.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_incompatible_type_for_trait.txt
index 584213420..2cbf657e5 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_incompatible_type_for_trait.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_incompatible_type_for_trait.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/compiler/ty/list_iter.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/compiler/ty/list_iter.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_mismatched_type.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_mismatched_type.txt
index 2610e4e20..1142dc2ac 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_mismatched_type.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_mismatched_type.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/runtime/compiler_support.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/runtime/compiler_support.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable.txt
index 8dc53391e..c709de95f 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/driver/subcommand/repl.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/driver/subcommand/repl.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -36,7 +43,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -47,7 +53,14 @@
                     SnippetWorkspaceEdit {
                         changes: Some(
                             {
-                                "file:///test/driver/subcommand/repl.rs": [
+                                Url {
+                                    scheme: "file",
+                                    host: None,
+                                    port: None,
+                                    path: "/test/driver/subcommand/repl.rs",
+                                    query: None,
+                                    fragment: None,
+                                }: [
                                     TextEdit {
                                         range: Range {
                                             start: Position {
@@ -70,6 +83,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_hint.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_hint.txt
index c8703194c..632f438d7 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_hint.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_hint.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/driver/subcommand/repl.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/driver/subcommand/repl.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -36,7 +43,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -47,7 +53,14 @@
                     SnippetWorkspaceEdit {
                         changes: Some(
                             {
-                                "file:///test/driver/subcommand/repl.rs": [
+                                Url {
+                                    scheme: "file",
+                                    host: None,
+                                    port: None,
+                                    path: "/test/driver/subcommand/repl.rs",
+                                    query: None,
+                                    fragment: None,
+                                }: [
                                     TextEdit {
                                         range: Range {
                                             start: Position {
@@ -70,6 +83,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_info.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_info.txt
index dc93227ad..c0b79428d 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_info.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_unused_variable_as_info.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/driver/subcommand/repl.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/driver/subcommand/repl.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -36,7 +43,6 @@
         fixes: [
             CodeAction {
                 title: "consider prefixing with an underscore",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -47,7 +53,14 @@
                     SnippetWorkspaceEdit {
                         changes: Some(
                             {
-                                "file:///test/driver/subcommand/repl.rs": [
+                                Url {
+                                    scheme: "file",
+                                    host: None,
+                                    port: None,
+                                    path: "/test/driver/subcommand/repl.rs",
+                                    query: None,
+                                    fragment: None,
+                                }: [
                                     TextEdit {
                                         range: Range {
                                             start: Position {
@@ -70,6 +83,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/rustc_wrong_number_of_parameters.txt b/crates/rust-analyzer/src/diagnostics/test_data/rustc_wrong_number_of_parameters.txt
index ba1b98b33..782c72dbd 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/rustc_wrong_number_of_parameters.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/rustc_wrong_number_of_parameters.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/compiler/ty/select.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/compiler/ty/select.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -29,7 +36,14 @@
                 [
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/compiler/ty/select.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/compiler/ty/select.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 218,
diff --git a/crates/rust-analyzer/src/diagnostics/test_data/snap_multi_line_fix.txt b/crates/rust-analyzer/src/diagnostics/test_data/snap_multi_line_fix.txt
index 81f752672..d3f27ab6a 100644
--- a/crates/rust-analyzer/src/diagnostics/test_data/snap_multi_line_fix.txt
+++ b/crates/rust-analyzer/src/diagnostics/test_data/snap_multi_line_fix.txt
@@ -1,6 +1,13 @@
 [
     MappedRustDiagnostic {
-        url: "file:///test/src/main.rs",
+        url: Url {
+            scheme: "file",
+            host: None,
+            port: None,
+            path: "/test/src/main.rs",
+            query: None,
+            fragment: None,
+        },
         diagnostic: Diagnostic {
             range: Range {
                 start: Position {
@@ -29,7 +36,14 @@
                 [
                     DiagnosticRelatedInformation {
                         location: Location {
-                            uri: "file:///test/src/main.rs",
+                            uri: Url {
+                                scheme: "file",
+                                host: None,
+                                port: None,
+                                path: "/test/src/main.rs",
+                                query: None,
+                                fragment: None,
+                            },
                             range: Range {
                                 start: Position {
                                     line: 2,
@@ -51,7 +65,6 @@
         fixes: [
             CodeAction {
                 title: "return the expression directly",
-                id: None,
                 group: None,
                 kind: Some(
                     CodeActionKind(
@@ -62,7 +75,14 @@
                     SnippetWorkspaceEdit {
                         changes: Some(
                             {
-                                "file:///test/src/main.rs": [
+                                Url {
+                                    scheme: "file",
+                                    host: None,
+                                    port: None,
+                                    path: "/test/src/main.rs",
+                                    query: None,
+                                    fragment: None,
+                                }: [
                                     TextEdit {
                                         range: Range {
                                             start: Position {
@@ -98,6 +118,7 @@
                 is_preferred: Some(
                     true,
                 ),
+                data: None,
             },
         ],
     },
diff --git a/crates/rust-analyzer/src/diagnostics/to_proto.rs b/crates/rust-analyzer/src/diagnostics/to_proto.rs
index b949577c1..15145415b 100644
--- a/crates/rust-analyzer/src/diagnostics/to_proto.rs
+++ b/crates/rust-analyzer/src/diagnostics/to_proto.rs
@@ -110,7 +110,6 @@ fn map_rust_child_diagnostic(
     } else {
         MappedRustChildDiagnostic::SuggestedFix(lsp_ext::CodeAction {
             title: rd.message.clone(),
-            id: None,
             group: None,
             kind: Some(lsp_types::CodeActionKind::QUICKFIX),
             edit: Some(lsp_ext::SnippetWorkspaceEdit {
@@ -119,6 +118,7 @@ fn map_rust_child_diagnostic(
                 document_changes: None,
             }),
             is_preferred: Some(true),
+            data: None,
         })
     }
 }
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 049c583a4..95659b0db 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -806,11 +806,11 @@ fn handle_fixes(
         let edit = to_proto::snippet_workspace_edit(&snap, fix.source_change)?;
         let action = lsp_ext::CodeAction {
             title: fix.label.to_string(),
-            id: None,
             group: None,
             kind: Some(CodeActionKind::QUICKFIX),
             edit: Some(edit),
             is_preferred: Some(false),
+            data: None,
         };
         res.push(action);
     }
@@ -852,11 +852,11 @@ pub(crate) fn handle_code_action(
 
     handle_fixes(&snap, &params, &mut res)?;
 
-    if snap.config.client_caps.resolve_code_action {
+    if snap.config.client_caps.code_action_resolve {
         for (index, assist) in
             snap.analysis.unresolved_assists(&snap.config.assist, frange)?.into_iter().enumerate()
         {
-            res.push(to_proto::unresolved_code_action(&snap, assist, index)?);
+            res.push(to_proto::unresolved_code_action(&snap, params.clone(), assist, index)?);
         }
     } else {
         for assist in snap.analysis.resolved_assists(&snap.config.assist, frange)?.into_iter() {
@@ -867,11 +867,16 @@ pub(crate) fn handle_code_action(
     Ok(Some(res))
 }
 
-pub(crate) fn handle_resolve_code_action(
+pub(crate) fn handle_code_action_resolve(
     mut snap: GlobalStateSnapshot,
-    params: lsp_ext::ResolveCodeActionParams,
-) -> Result<Option<lsp_ext::SnippetWorkspaceEdit>> {
-    let _p = profile::span("handle_resolve_code_action");
+    mut code_action: lsp_ext::CodeAction,
+) -> Result<lsp_ext::CodeAction> {
+    let _p = profile::span("handle_code_action_resolve");
+    let params = match code_action.data.take() {
+        Some(it) => it,
+        None => Err("can't resolve code action without data")?,
+    };
+
     let file_id = from_proto::file_id(&snap, &params.code_action_params.text_document.uri)?;
     let line_index = snap.analysis.file_line_index(file_id)?;
     let range = from_proto::text_range(&line_index, params.code_action_params.range);
@@ -888,7 +893,9 @@ pub(crate) fn handle_resolve_code_action(
     let index = index.parse::<usize>().unwrap();
     let assist = &assists[index];
     assert!(assist.assist.id.0 == id);
-    Ok(to_proto::resolved_code_action(&snap, assist.clone())?.edit)
+    let edit = to_proto::resolved_code_action(&snap, assist.clone())?.edit;
+    code_action.edit = edit;
+    Ok(code_action)
 }
 
 pub(crate) fn handle_code_lens(
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index f31f8d900..a7c3028e4 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -113,22 +113,6 @@ pub struct JoinLinesParams {
     pub ranges: Vec<Range>,
 }
 
-pub enum ResolveCodeActionRequest {}
-
-impl Request for ResolveCodeActionRequest {
-    type Params = ResolveCodeActionParams;
-    type Result = Option<SnippetWorkspaceEdit>;
-    const METHOD: &'static str = "experimental/resolveCodeAction";
-}
-
-/// Params for the ResolveCodeActionRequest
-#[derive(Debug, Eq, PartialEq, Clone, Deserialize, Serialize)]
-#[serde(rename_all = "camelCase")]
-pub struct ResolveCodeActionParams {
-    pub code_action_params: lsp_types::CodeActionParams,
-    pub id: String,
-}
-
 pub enum OnEnter {}
 
 impl Request for OnEnter {
@@ -265,13 +249,18 @@ impl Request for CodeActionRequest {
     const METHOD: &'static str = "textDocument/codeAction";
 }
 
+pub enum CodeActionResolveRequest {}
+impl Request for CodeActionResolveRequest {
+    type Params = CodeAction;
+    type Result = CodeAction;
+    const METHOD: &'static str = "codeAction/resolve";
+}
+
 #[derive(Debug, PartialEq, Clone, Default, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct CodeAction {
     pub title: String,
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub id: Option<String>,
-    #[serde(skip_serializing_if = "Option::is_none")]
     pub group: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub kind: Option<CodeActionKind>,
@@ -282,6 +271,16 @@ pub struct CodeAction {
     pub edit: Option<SnippetWorkspaceEdit>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub is_preferred: Option<bool>,
+
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub data: Option<CodeActionData>,
+}
+
+#[derive(Debug, Eq, PartialEq, Clone, Deserialize, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct CodeActionData {
+    pub code_action_params: lsp_types::CodeActionParams,
+    pub id: String,
 }
 
 #[derive(Debug, Eq, PartialEq, Clone, Default, Deserialize, Serialize)]
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index d504572a8..6e6cac42e 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -435,7 +435,7 @@ impl GlobalState {
             .on::<lsp_ext::Runnables>(handlers::handle_runnables)
             .on::<lsp_ext::InlayHints>(handlers::handle_inlay_hints)
             .on::<lsp_ext::CodeActionRequest>(handlers::handle_code_action)
-            .on::<lsp_ext::ResolveCodeActionRequest>(handlers::handle_resolve_code_action)
+            .on::<lsp_ext::CodeActionResolveRequest>(handlers::handle_code_action_resolve)
             .on::<lsp_ext::HoverRequest>(handlers::handle_hover)
             .on::<lsp_ext::ExternalDocs>(handlers::handle_open_docs)
             .on::<lsp_types::request::OnTypeFormatting>(handlers::handle_on_type_formatting)
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 92b7c7b68..4bdf4bf0f 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -426,6 +426,7 @@ fn semantic_token_type_and_modifiers(
             HighlightModifier::Consuming => semantic_tokens::CONSUMING,
             HighlightModifier::Unsafe => semantic_tokens::UNSAFE,
             HighlightModifier::Callable => semantic_tokens::CALLABLE,
+            HighlightModifier::Static => lsp_types::SemanticTokenModifier::STATIC,
         };
         mods |= modifier;
     }
@@ -734,16 +735,20 @@ pub(crate) fn code_action_kind(kind: AssistKind) -> lsp_types::CodeActionKind {
 
 pub(crate) fn unresolved_code_action(
     snap: &GlobalStateSnapshot,
+    code_action_params: lsp_types::CodeActionParams,
     assist: Assist,
     index: usize,
 ) -> Result<lsp_ext::CodeAction> {
     let res = lsp_ext::CodeAction {
         title: assist.label.to_string(),
-        id: Some(format!("{}:{}", assist.id.0, index.to_string())),
         group: assist.group.filter(|_| snap.config.client_caps.code_action_group).map(|gr| gr.0),
         kind: Some(code_action_kind(assist.id.1)),
         edit: None,
         is_preferred: None,
+        data: Some(lsp_ext::CodeActionData {
+            id: format!("{}:{}", assist.id.0, index.to_string()),
+            code_action_params,
+        }),
     };
     Ok(res)
 }
@@ -753,13 +758,19 @@ pub(crate) fn resolved_code_action(
     assist: ResolvedAssist,
 ) -> Result<lsp_ext::CodeAction> {
     let change = assist.source_change;
-    unresolved_code_action(snap, assist.assist, 0).and_then(|it| {
-        Ok(lsp_ext::CodeAction {
-            id: None,
-            edit: Some(snippet_workspace_edit(snap, change)?),
-            ..it
-        })
-    })
+    let res = lsp_ext::CodeAction {
+        edit: Some(snippet_workspace_edit(snap, change)?),
+        title: assist.assist.label.to_string(),
+        group: assist
+            .assist
+            .group
+            .filter(|_| snap.config.client_caps.code_action_group)
+            .map(|gr| gr.0),
+        kind: Some(code_action_kind(assist.assist.id.1)),
+        is_preferred: None,
+        data: None,
+    };
+    Ok(res)
 }
 
 pub(crate) fn runnable(
diff --git a/crates/stdx/src/lib.rs b/crates/stdx/src/lib.rs
index 59d89f47d..374ed5910 100644
--- a/crates/stdx/src/lib.rs
+++ b/crates/stdx/src/lib.rs
@@ -1,8 +1,5 @@
 //! Missing batteries for standard libraries.
-use std::{
-    sync::atomic::{AtomicUsize, Ordering},
-    time::Instant,
-};
+use std::time::Instant;
 
 mod macros;
 pub mod panic_context;
@@ -150,31 +147,6 @@ where
     left
 }
 
-pub struct RacyFlag(AtomicUsize);
-
-impl RacyFlag {
-    pub const fn new() -> RacyFlag {
-        RacyFlag(AtomicUsize::new(!0))
-    }
-
-    pub fn get(&self, init: impl FnMut() -> bool) -> bool {
-        let mut init = Some(init);
-        self.get_impl(&mut || init.take().map_or(false, |mut f| f()))
-    }
-
-    fn get_impl(&self, init: &mut dyn FnMut() -> bool) -> bool {
-        match self.0.load(Ordering::Relaxed) {
-            0 => false,
-            1 => true,
-            _ => {
-                let res = init();
-                self.0.store(if res { 1 } else { 0 }, Ordering::Relaxed);
-                res
-            }
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/crates/syntax/Cargo.toml b/crates/syntax/Cargo.toml
index 61d2acb49..1fe907753 100644
--- a/crates/syntax/Cargo.toml
+++ b/crates/syntax/Cargo.toml
@@ -13,7 +13,7 @@ doctest = false
 [dependencies]
 itertools = "0.9.0"
 rowan = "0.10.0"
-rustc_lexer = { version = "686.0.0", package = "rustc-ap-rustc_lexer" }
+rustc_lexer = { version = "688.0.0", package = "rustc-ap-rustc_lexer" }
 rustc-hash = "1.1.0"
 arrayvec = "0.5.1"
 once_cell = "1.3.1"
diff --git a/crates/syntax/src/algo.rs b/crates/syntax/src/algo.rs
index 30adb7217..320c430c9 100644
--- a/crates/syntax/src/algo.rs
+++ b/crates/syntax/src/algo.rs
@@ -111,18 +111,28 @@ pub enum InsertPosition<T> {
 
 type FxIndexMap<K, V> = IndexMap<K, V, BuildHasherDefault<rustc_hash::FxHasher>>;
 
+#[derive(Debug, Hash, PartialEq, Eq)]
+enum TreeDiffInsertPos {
+    After(SyntaxElement),
+    AsFirstChild(SyntaxElement),
+}
+
 #[derive(Debug)]
 pub struct TreeDiff {
     replacements: FxHashMap<SyntaxElement, SyntaxElement>,
     deletions: Vec<SyntaxElement>,
     // the vec as well as the indexmap are both here to preserve order
-    insertions: FxIndexMap<SyntaxElement, Vec<SyntaxElement>>,
+    insertions: FxIndexMap<TreeDiffInsertPos, Vec<SyntaxElement>>,
 }
 
 impl TreeDiff {
     pub fn into_text_edit(&self, builder: &mut TextEditBuilder) {
         for (anchor, to) in self.insertions.iter() {
-            to.iter().for_each(|to| builder.insert(anchor.text_range().end(), to.to_string()));
+            let offset = match anchor {
+                TreeDiffInsertPos::After(it) => it.text_range().end(),
+                TreeDiffInsertPos::AsFirstChild(it) => it.text_range().start(),
+            };
+            to.iter().for_each(|to| builder.insert(offset, to.to_string()));
         }
         for (from, to) in self.replacements.iter() {
             builder.replace(from.text_range(), to.to_string())
@@ -188,19 +198,20 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
             let lhs_child = lhs_children.next();
             match (lhs_child.clone(), rhs_children.next()) {
                 (None, None) => break,
-                (None, Some(element)) => match last_lhs.clone() {
-                    Some(prev) => {
-                        mark::hit!(diff_insert);
-                        diff.insertions.entry(prev).or_insert_with(Vec::new).push(element);
-                    }
-                    // first iteration, this means we got no anchor element to insert after
-                    // therefor replace the parent node instead
-                    None => {
-                        mark::hit!(diff_replace_parent);
-                        diff.replacements.insert(lhs.clone().into(), rhs.clone().into());
-                        break;
-                    }
-                },
+                (None, Some(element)) => {
+                    let insert_pos = match last_lhs.clone() {
+                        Some(prev) => {
+                            mark::hit!(diff_insert);
+                            TreeDiffInsertPos::After(prev)
+                        }
+                        // first iteration, insert into out parent as the first child
+                        None => {
+                            mark::hit!(diff_insert_as_first_child);
+                            TreeDiffInsertPos::AsFirstChild(lhs.clone().into())
+                        }
+                    };
+                    diff.insertions.entry(insert_pos).or_insert_with(Vec::new).push(element);
+                }
                 (Some(element), None) => {
                     mark::hit!(diff_delete);
                     diff.deletions.push(element);
@@ -224,8 +235,15 @@ pub fn diff(from: &SyntaxNode, to: &SyntaxNode) -> TreeDiff {
                         }
                     }
                     let drain = look_ahead_scratch.drain(..);
-                    if let Some(prev) = last_lhs.clone().filter(|_| insert) {
-                        diff.insertions.entry(prev).or_insert_with(Vec::new).extend(drain);
+                    if insert {
+                        let insert_pos = if let Some(prev) = last_lhs.clone().filter(|_| insert) {
+                            TreeDiffInsertPos::After(prev)
+                        } else {
+                            mark::hit!(insert_first_child);
+                            TreeDiffInsertPos::AsFirstChild(lhs.clone().into())
+                        };
+
+                        diff.insertions.entry(insert_pos).or_insert_with(Vec::new).extend(drain);
                         rhs_children = rhs_children_clone;
                     } else {
                         go(diff, lhs_ele, rhs_ele)
@@ -632,18 +650,19 @@ mod tests {
 
     #[test]
     fn replace_parent() {
-        mark::check!(diff_replace_parent);
+        mark::check!(diff_insert_as_first_child);
         check_diff(
             r#""#,
             r#"use foo::bar;"#,
             expect![[r#"
                 insertions:
 
-
+                Line 0: AsFirstChild(Node([email protected]))
+                -> use foo::bar;
 
                 replacements:
 
-                Line 0: Node([email protected]) -> use foo::bar;
+
 
                 deletions:
 
@@ -666,7 +685,7 @@ use baz;"#,
             expect![[r#"
                 insertions:
 
-                Line 2: Node([email protected])
+                Line 2: After(Node([email protected]))
                 -> "\n"
                 -> use baz;
 
@@ -694,7 +713,7 @@ use baz;"#,
             expect![[r#"
                 insertions:
 
-                Line 2: Token([email protected] "\n")
+                Line 2: After(Token([email protected] "\n"))
                 -> use bar;
                 -> "\n"
 
@@ -722,7 +741,7 @@ use baz;"#,
             expect![[r#"
                 insertions:
 
-                Line 0: Token([email protected] "\n")
+                Line 0: After(Token([email protected] "\n"))
                 -> use foo;
                 -> "\n"
 
@@ -738,6 +757,36 @@ use baz;"#,
     }
 
     #[test]
+    fn first_child_insertion() {
+        mark::check!(insert_first_child);
+        check_diff(
+            r#"fn main() {
+        stdi
+    }"#,
+            r#"use foo::bar;
+
+    fn main() {
+        stdi
+    }"#,
+            expect![[r#"
+                insertions:
+
+                Line 0: AsFirstChild(Node([email protected]))
+                -> use foo::bar;
+                -> "\n\n    "
+
+                replacements:
+
+
+
+                deletions:
+
+
+            "#]],
+        );
+    }
+
+    #[test]
     fn delete_last() {
         mark::check!(diff_delete);
         check_diff(
@@ -779,7 +828,7 @@ use crate::AstNode;
             expect![[r#"
                 insertions:
 
-                Line 1: Node([email protected])
+                Line 1: After(Node([email protected]))
                 -> "\n\n"
                 -> use crate::AstNode;
 
@@ -845,10 +894,10 @@ use std::ops::{self, RangeInclusive};
             expect![[r#"
                 insertions:
 
-                Line 2: Node([email protected])
+                Line 2: After(Node([email protected]))
                 -> ::
                 -> fmt
-                Line 6: Token([email protected] "\n")
+                Line 6: After(Token([email protected] "\n"))
                 -> use std::hash::BuildHasherDefault;
                 -> "\n"
                 -> use std::ops::{self, RangeInclusive};
@@ -892,14 +941,14 @@ fn main() {
             expect![[r#"
                 insertions:
 
-                Line 3: Node([email protected])
+                Line 3: After(Node([email protected]))
                 -> " "
                 -> match Err(92) {
                         Ok(it) => it,
                         _ => return,
                     }
                 -> ;
-                Line 3: Node([email protected])
+                Line 3: After(Node([email protected]))
                 -> "\n    "
                 -> foo(x);
 
@@ -934,14 +983,18 @@ fn main() {
             _ => format!("{}", syn),
         };
 
-        let insertions = diff.insertions.iter().format_with("\n", |(k, v), f| {
-            f(&format!(
-                "Line {}: {:?}\n-> {}",
-                line_number(k),
-                k,
-                v.iter().format_with("\n-> ", |v, f| f(&fmt_syntax(v)))
-            ))
-        });
+        let insertions =
+            diff.insertions.iter().format_with("\n", |(k, v), f| -> Result<(), std::fmt::Error> {
+                f(&format!(
+                    "Line {}: {:?}\n-> {}",
+                    line_number(match k {
+                        super::TreeDiffInsertPos::After(syn) => syn,
+                        super::TreeDiffInsertPos::AsFirstChild(syn) => syn,
+                    }),
+                    k,
+                    v.iter().format_with("\n-> ", |v, f| f(&fmt_syntax(v)))
+                ))
+            });
 
         let replacements = diff
             .replacements
diff --git a/crates/syntax/src/ast.rs b/crates/syntax/src/ast.rs
index 8a0e3d27b..7844f9ed6 100644
--- a/crates/syntax/src/ast.rs
+++ b/crates/syntax/src/ast.rs
@@ -115,10 +115,10 @@ fn test_doc_comment_none() {
 }
 
 #[test]
-fn test_doc_comment_of_items() {
+fn test_outer_doc_comment_of_items() {
     let file = SourceFile::parse(
         r#"
-        //! doc
+        /// doc
         // non-doc
         mod foo {}
         "#,
@@ -130,6 +130,21 @@ fn test_doc_comment_of_items() {
 }
 
 #[test]
+fn test_inner_doc_comment_of_items() {
+    let file = SourceFile::parse(
+        r#"
+        //! doc
+        // non-doc
+        mod foo {}
+        "#,
+    )
+    .ok()
+    .unwrap();
+    let module = file.syntax().descendants().find_map(Module::cast).unwrap();
+    assert!(module.doc_comment_text().is_none());
+}
+
+#[test]
 fn test_doc_comment_of_statics() {
     let file = SourceFile::parse(
         r#"
diff --git a/crates/syntax/src/ast/token_ext.rs b/crates/syntax/src/ast/token_ext.rs
index e4e512f2e..2661c753e 100644
--- a/crates/syntax/src/ast/token_ext.rs
+++ b/crates/syntax/src/ast/token_ext.rs
@@ -14,16 +14,15 @@ use crate::{
 
 impl ast::Comment {
     pub fn kind(&self) -> CommentKind {
-        kind_by_prefix(self.text())
+        CommentKind::from_text(self.text())
     }
 
     pub fn prefix(&self) -> &'static str {
-        for (prefix, k) in COMMENT_PREFIX_TO_KIND.iter() {
-            if *k == self.kind() && self.text().starts_with(prefix) {
-                return prefix;
-            }
-        }
-        unreachable!()
+        let &(prefix, _kind) = CommentKind::BY_PREFIX
+            .iter()
+            .find(|&(prefix, kind)| self.kind() == *kind && self.text().starts_with(prefix))
+            .unwrap();
+        prefix
     }
 }
 
@@ -55,29 +54,25 @@ pub enum CommentPlacement {
     Outer,
 }
 
-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) }),
-        ("/*!", CommentKind { shape: Block, doc: Some(Inner) }),
-        ("//", CommentKind { shape: Line, doc: None }),
-        ("/*", CommentKind { shape: Block, doc: None }),
-    ]
-};
+impl CommentKind {
+    const BY_PREFIX: [(&'static str, CommentKind); 8] = [
+        ("/**/", CommentKind { shape: CommentShape::Block, doc: None }),
+        ("////", CommentKind { shape: CommentShape::Line, doc: None }),
+        ("///", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Outer) }),
+        ("//!", CommentKind { shape: CommentShape::Line, doc: Some(CommentPlacement::Inner) }),
+        ("/**", CommentKind { shape: CommentShape::Block, doc: Some(CommentPlacement::Outer) }),
+        ("/*!", CommentKind { shape: CommentShape::Block, doc: Some(CommentPlacement::Inner) }),
+        ("//", CommentKind { shape: CommentShape::Line, doc: None }),
+        ("/*", CommentKind { shape: CommentShape::Block, doc: None }),
+    ];
 
-fn kind_by_prefix(text: &str) -> CommentKind {
-    if text == "/**/" {
-        return CommentKind { shape: CommentShape::Block, doc: None };
-    }
-    for (prefix, kind) in COMMENT_PREFIX_TO_KIND.iter() {
-        if text.starts_with(prefix) {
-            return *kind;
-        }
+    pub(crate) fn from_text(text: &str) -> CommentKind {
+        let &(_prefix, kind) = CommentKind::BY_PREFIX
+            .iter()
+            .find(|&(prefix, _kind)| text.starts_with(prefix))
+            .unwrap();
+        kind
     }
-    panic!("bad comment text: {:?}", text)
 }
 
 impl ast::Whitespace {
diff --git a/crates/syntax/src/parsing/text_tree_sink.rs b/crates/syntax/src/parsing/text_tree_sink.rs
index c1b5f246d..997bc5d28 100644
--- a/crates/syntax/src/parsing/text_tree_sink.rs
+++ b/crates/syntax/src/parsing/text_tree_sink.rs
@@ -5,6 +5,7 @@ use std::mem;
 use parser::{ParseError, TreeSink};
 
 use crate::{
+    ast,
     parsing::Token,
     syntax_node::GreenNode,
     SmolStr, SyntaxError,
@@ -153,24 +154,22 @@ fn n_attached_trivias<'a>(
 
             while let Some((i, (kind, text))) = trivias.next() {
                 match kind {
-                    WHITESPACE => {
-                        if text.contains("\n\n") {
-                            // we check whether the next token is a doc-comment
-                            // and skip the whitespace in this case
-                            if let Some((peek_kind, peek_text)) =
-                                trivias.peek().map(|(_, pair)| pair)
-                            {
-                                if *peek_kind == COMMENT
-                                    && peek_text.starts_with("///")
-                                    && !peek_text.starts_with("////")
-                                {
-                                    continue;
-                                }
+                    WHITESPACE if text.contains("\n\n") => {
+                        // we check whether the next token is a doc-comment
+                        // and skip the whitespace in this case
+                        if let Some((COMMENT, peek_text)) = trivias.peek().map(|(_, pair)| pair) {
+                            let comment_kind = ast::CommentKind::from_text(peek_text);
+                            if comment_kind.doc == Some(ast::CommentPlacement::Outer) {
+                                continue;
                             }
-                            break;
                         }
+                        break;
                     }
                     COMMENT => {
+                        let comment_kind = ast::CommentKind::from_text(text);
+                        if comment_kind.doc == Some(ast::CommentPlacement::Inner) {
+                            break;
+                        }
                         res = i + 1;
                     }
                     _ => (),
diff --git a/crates/syntax/test_data/parser/ok/0037_mod.rast b/crates/syntax/test_data/parser/ok/0037_mod.rast
index 1d5d94bde..35577272e 100644
--- a/crates/syntax/test_data/parser/ok/0037_mod.rast
+++ b/crates/syntax/test_data/parser/ok/0037_mod.rast
@@ -1,9 +1,9 @@
 [email protected]
   [email protected] "// https://github.com ..."
   [email protected] "\n\n"
-  MODULE@62..93
-    COMMENT@62..70 "//! docs"
-    WHITESPACE@70..71 "\n"
+  COMMENT@62..70 "//! docs"
+  WHITESPACE@70..71 "\n"
+  MODULE@71..93
     [email protected] "// non-docs"
     [email protected] "\n"
     [email protected] "mod"