15 files changed, 646 insertions, 338 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index 0ace80a1e..1c911a8b2 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -25,7 +25,7 @@ use syntax::{
 use text_edit::TextEdit;
 use unlinked_file::UnlinkedFile;
 
-use crate::{FileId, Label, SourceChange};
+use crate::{Assist, AssistId, AssistKind, FileId, Label, SourceChange};
 
 use self::fixes::DiagnosticWithFix;
 
@@ -35,7 +35,7 @@ pub struct Diagnostic {
     pub message: String,
     pub range: TextRange,
     pub severity: Severity,
-    pub fix: Option<Fix>,
+    pub fix: Option<Assist>,
     pub unused: bool,
     pub code: Option<DiagnosticCode>,
 }
@@ -56,7 +56,7 @@ impl Diagnostic {
         }
     }
 
-    fn with_fix(self, fix: Option<Fix>) -> Self {
+    fn with_fix(self, fix: Option<Assist>) -> Self {
         Self { fix, ..self }
     }
 
@@ -69,21 +69,6 @@ impl Diagnostic {
     }
 }
 
-#[derive(Debug)]
-pub struct Fix {
-    pub label: Label,
-    pub source_change: SourceChange,
-    /// Allows to trigger the fix only when the caret is in the range given
-    pub fix_trigger_range: TextRange,
-}
-
-impl Fix {
-    fn new(label: &str, source_change: SourceChange, fix_trigger_range: TextRange) -> Self {
-        let label = Label::new(label);
-        Self { label, source_change, fix_trigger_range }
-    }
-}
-
 #[derive(Debug, Copy, Clone)]
 pub enum Severity {
     Error,
@@ -99,6 +84,7 @@ pub struct DiagnosticsConfig {
 pub(crate) fn diagnostics(
     db: &RootDatabase,
     config: &DiagnosticsConfig,
+    resolve: bool,
     file_id: FileId,
 ) -> Vec<Diagnostic> {
     let _p = profile::span("diagnostics");
@@ -122,25 +108,25 @@ pub(crate) fn diagnostics(
     let res = RefCell::new(res);
     let sink_builder = DiagnosticSinkBuilder::new()
         .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::MissingFields, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::MissingOkOrSomeInTailExpr, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::NoSuchField, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::RemoveThisSemicolon, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::IncorrectCase, _>(|d| {
-            res.borrow_mut().push(warning_with_fix(d, &sema));
+            res.borrow_mut().push(warning_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::ReplaceFilterMapNextWithFindMap, _>(|d| {
-            res.borrow_mut().push(warning_with_fix(d, &sema));
+            res.borrow_mut().push(warning_with_fix(d, &sema, resolve));
         })
         .on::<hir::diagnostics::InactiveCode, _>(|d| {
             // If there's inactive code somewhere in a macro, don't propagate to the call-site.
@@ -167,7 +153,7 @@ pub(crate) fn diagnostics(
             // Override severity and mark as unused.
             res.borrow_mut().push(
                 Diagnostic::hint(range, d.message())
-                    .with_fix(d.fix(&sema))
+                    .with_fix(d.fix(&sema, resolve))
                     .with_code(Some(d.code())),
             );
         })
@@ -223,15 +209,23 @@ pub(crate) fn diagnostics(
     res.into_inner()
 }
 
-fn diagnostic_with_fix<D: DiagnosticWithFix>(d: &D, sema: &Semantics<RootDatabase>) -> Diagnostic {
+fn diagnostic_with_fix<D: DiagnosticWithFix>(
+    d: &D,
+    sema: &Semantics<RootDatabase>,
+    resolve: bool,
+) -> Diagnostic {
     Diagnostic::error(sema.diagnostics_display_range(d.display_source()).range, d.message())
-        .with_fix(d.fix(&sema))
+        .with_fix(d.fix(&sema, resolve))
         .with_code(Some(d.code()))
 }
 
-fn warning_with_fix<D: DiagnosticWithFix>(d: &D, sema: &Semantics<RootDatabase>) -> Diagnostic {
+fn warning_with_fix<D: DiagnosticWithFix>(
+    d: &D,
+    sema: &Semantics<RootDatabase>,
+    resolve: bool,
+) -> Diagnostic {
     Diagnostic::hint(sema.diagnostics_display_range(d.display_source()).range, d.message())
-        .with_fix(d.fix(&sema))
+        .with_fix(d.fix(&sema, resolve))
         .with_code(Some(d.code()))
 }
 
@@ -261,7 +255,8 @@ fn check_unnecessary_braces_in_use_statement(
 
         acc.push(
             Diagnostic::hint(use_range, "Unnecessary braces in use statement".to_string())
-                .with_fix(Some(Fix::new(
+                .with_fix(Some(fix(
+                    "remove_braces",
                     "Remove unnecessary braces",
                     SourceChange::from_text_edit(file_id, edit),
                     use_range,
@@ -284,6 +279,23 @@ fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
     None
 }
 
+fn fix(id: &'static str, label: &str, source_change: SourceChange, target: TextRange) -> Assist {
+    let mut res = unresolved_fix(id, label, target);
+    res.source_change = Some(source_change);
+    res
+}
+
+fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
+    assert!(!id.contains(' '));
+    Assist {
+        id: AssistId(id, AssistKind::QuickFix),
+        label: Label::new(label),
+        group: None,
+        target,
+        source_change: None,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
@@ -302,16 +314,17 @@ mod tests {
 
         let (analysis, file_position) = fixture::position(ra_fixture_before);
         let diagnostic = analysis
-            .diagnostics(&DiagnosticsConfig::default(), file_position.file_id)
+            .diagnostics(&DiagnosticsConfig::default(), true, file_position.file_id)
             .unwrap()
             .pop()
             .unwrap();
         let fix = diagnostic.fix.unwrap();
         let actual = {
-            let file_id = *fix.source_change.source_file_edits.keys().next().unwrap();
+            let source_change = fix.source_change.unwrap();
+            let file_id = *source_change.source_file_edits.keys().next().unwrap();
             let mut actual = analysis.file_text(file_id).unwrap().to_string();
 
-            for edit in fix.source_change.source_file_edits.values() {
+            for edit in source_change.source_file_edits.values() {
                 edit.apply(&mut actual);
             }
             actual
@@ -319,9 +332,9 @@ mod tests {
 
         assert_eq_text!(&after, &actual);
         assert!(
-            fix.fix_trigger_range.contains_inclusive(file_position.offset),
+            fix.target.contains_inclusive(file_position.offset),
             "diagnostic fix range {:?} does not touch cursor position {:?}",
-            fix.fix_trigger_range,
+            fix.target,
             file_position.offset
         );
     }
@@ -330,7 +343,7 @@ mod tests {
     fn check_no_fix(ra_fixture: &str) {
         let (analysis, file_position) = fixture::position(ra_fixture);
         let diagnostic = analysis
-            .diagnostics(&DiagnosticsConfig::default(), file_position.file_id)
+            .diagnostics(&DiagnosticsConfig::default(), true, file_position.file_id)
             .unwrap()
             .pop()
             .unwrap();
@@ -344,7 +357,7 @@ mod tests {
         let diagnostics = files
             .into_iter()
             .flat_map(|file_id| {
-                analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap()
+                analysis.diagnostics(&DiagnosticsConfig::default(), true, file_id).unwrap()
             })
             .collect::<Vec<_>>();
         assert_eq!(diagnostics.len(), 0, "unexpected diagnostics:\n{:#?}", diagnostics);
@@ -352,7 +365,8 @@ mod tests {
 
     fn check_expect(ra_fixture: &str, expect: Expect) {
         let (analysis, file_id) = fixture::file(ra_fixture);
-        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        let diagnostics =
+            analysis.diagnostics(&DiagnosticsConfig::default(), true, file_id).unwrap();
         expect.assert_debug_eq(&diagnostics)
     }
 
@@ -665,24 +679,31 @@ fn test_fn() {
                         range: 0..8,
                         severity: Error,
                         fix: Some(
-                            Fix {
+                            Assist {
+                                id: AssistId(
+                                    "create_module",
+                                    QuickFix,
+                                ),
                                 label: "Create module",
-                                source_change: SourceChange {
-                                    source_file_edits: {},
-                                    file_system_edits: [
-                                        CreateFile {
-                                            dst: AnchoredPathBuf {
-                                                anchor: FileId(
-                                                    0,
-                                                ),
-                                                path: "foo.rs",
+                                group: None,
+                                target: 0..8,
+                                source_change: Some(
+                                    SourceChange {
+                                        source_file_edits: {},
+                                        file_system_edits: [
+                                            CreateFile {
+                                                dst: AnchoredPathBuf {
+                                                    anchor: FileId(
+                                                        0,
+                                                    ),
+                                                    path: "foo.rs",
+                                                },
+                                                initial_contents: "",
                                             },
-                                            initial_contents: "",
-                                        },
-                                    ],
-                                    is_snippet: false,
-                                },
-                                fix_trigger_range: 0..8,
+                                        ],
+                                        is_snippet: false,
+                                    },
+                                ),
                             },
                         ),
                         unused: false,
@@ -704,7 +725,7 @@ fn test_fn() {
             expect![[r#"
                 [
                     Diagnostic {
-                        message: "unresolved macro call",
+                        message: "unresolved macro `foo::bar!`",
                         range: 5..8,
                         severity: Error,
                         fix: None,
@@ -890,10 +911,11 @@ struct Foo {
 
         let (analysis, file_id) = fixture::file(r#"mod foo;"#);
 
-        let diagnostics = analysis.diagnostics(&config, file_id).unwrap();
+        let diagnostics = analysis.diagnostics(&config, true, file_id).unwrap();
         assert!(diagnostics.is_empty());
 
-        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        let diagnostics =
+            analysis.diagnostics(&DiagnosticsConfig::default(), true, file_id).unwrap();
         assert!(!diagnostics.is_empty());
     }
 
@@ -999,8 +1021,9 @@ impl TestStruct {
         let expected = r#"fn foo() {}"#;
 
         let (analysis, file_position) = fixture::position(input);
-        let diagnostics =
-            analysis.diagnostics(&DiagnosticsConfig::default(), file_position.file_id).unwrap();
+        let diagnostics = analysis
+            .diagnostics(&DiagnosticsConfig::default(), true, file_position.file_id)
+            .unwrap();
         assert_eq!(diagnostics.len(), 1);
 
         check_fix(input, expected);
diff --git a/crates/ide/src/diagnostics/field_shorthand.rs b/crates/ide/src/diagnostics/field_shorthand.rs
index 5c89e2170..2b1787f9b 100644
--- a/crates/ide/src/diagnostics/field_shorthand.rs
+++ b/crates/ide/src/diagnostics/field_shorthand.rs
@@ -5,7 +5,7 @@ use ide_db::{base_db::FileId, source_change::SourceChange};
 use syntax::{ast, match_ast, AstNode, SyntaxNode};
 use text_edit::TextEdit;
 
-use crate::{Diagnostic, Fix};
+use crate::{diagnostics::fix, Diagnostic};
 
 pub(super) fn check(acc: &mut Vec<Diagnostic>, file_id: FileId, node: &SyntaxNode) {
     match_ast! {
@@ -47,7 +47,8 @@ fn check_expr_field_shorthand(
         let field_range = record_field.syntax().text_range();
         acc.push(
             Diagnostic::hint(field_range, "Shorthand struct initialization".to_string()).with_fix(
-                Some(Fix::new(
+                Some(fix(
+                    "use_expr_field_shorthand",
                     "Use struct shorthand initialization",
                     SourceChange::from_text_edit(file_id, edit),
                     field_range,
@@ -86,7 +87,8 @@ fn check_pat_field_shorthand(
 
         let field_range = record_pat_field.syntax().text_range();
         acc.push(Diagnostic::hint(field_range, "Shorthand struct pattern".to_string()).with_fix(
-            Some(Fix::new(
+            Some(fix(
+                "use_pat_field_shorthand",
                 "Use struct field shorthand",
                 SourceChange::from_text_edit(file_id, edit),
                 field_range,
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
index 5fb3e2d91..7be8b3459 100644
--- a/crates/ide/src/diagnostics/fixes.rs
+++ b/crates/ide/src/diagnostics/fixes.rs
@@ -20,20 +20,30 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{diagnostics::Fix, references::rename::rename_with_semantics, FilePosition};
+use crate::{
+    diagnostics::{fix, unresolved_fix},
+    references::rename::rename_with_semantics,
+    Assist, FilePosition,
+};
 
 /// A [Diagnostic] that potentially has a fix available.
 ///
 /// [Diagnostic]: hir::diagnostics::Diagnostic
 pub(crate) trait DiagnosticWithFix: Diagnostic {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix>;
+    /// `resolve` determines if the diagnostic should fill in the `edit` field
+    /// of the assist.
+    ///
+    /// If `resolve` is false, the edit will be computed later, on demand, and
+    /// can be omitted.
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist>;
 }
 
 impl DiagnosticWithFix for UnresolvedModule {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let unresolved_module = self.decl.to_node(&root);
-        Some(Fix::new(
+        Some(fix(
+            "create_module",
             "Create module",
             FileSystemEdit::CreateFile {
                 dst: AnchoredPathBuf {
@@ -49,7 +59,7 @@ impl DiagnosticWithFix for UnresolvedModule {
 }
 
 impl DiagnosticWithFix for NoSuchField {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         missing_record_expr_field_fix(
             &sema,
@@ -60,7 +70,7 @@ impl DiagnosticWithFix for NoSuchField {
 }
 
 impl DiagnosticWithFix for MissingFields {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         // Note that although we could add a diagnostics to
         // fill the missing tuple field, e.g :
         // `struct A(usize);`
@@ -86,7 +96,8 @@ impl DiagnosticWithFix for MissingFields {
                 .into_text_edit(&mut builder);
             builder.finish()
         };
-        Some(Fix::new(
+        Some(fix(
+            "fill_missing_fields",
             "Fill struct fields",
             SourceChange::from_text_edit(self.file.original_file(sema.db), edit),
             sema.original_range(&field_list_parent.syntax()).range,
@@ -95,7 +106,7 @@ impl DiagnosticWithFix for MissingFields {
 }
 
 impl DiagnosticWithFix for MissingOkOrSomeInTailExpr {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let tail_expr = self.expr.to_node(&root);
         let tail_expr_range = tail_expr.syntax().text_range();
@@ -103,12 +114,12 @@ impl DiagnosticWithFix for MissingOkOrSomeInTailExpr {
         let edit = TextEdit::replace(tail_expr_range, replacement);
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
         let name = if self.required == "Ok" { "Wrap with Ok" } else { "Wrap with Some" };
-        Some(Fix::new(name, source_change, tail_expr_range))
+        Some(fix("wrap_tail_expr", name, source_change, tail_expr_range))
     }
 }
 
 impl DiagnosticWithFix for RemoveThisSemicolon {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
 
         let semicolon = self
@@ -123,12 +134,12 @@ impl DiagnosticWithFix for RemoveThisSemicolon {
         let edit = TextEdit::delete(semicolon);
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
 
-        Some(Fix::new("Remove this semicolon", source_change, semicolon))
+        Some(fix("remove_semicolon", "Remove this semicolon", source_change, semicolon))
     }
 }
 
 impl DiagnosticWithFix for IncorrectCase {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let name_node = self.ident.to_node(&root);
 
@@ -136,16 +147,19 @@ impl DiagnosticWithFix for IncorrectCase {
         let frange = name_node.original_file_range(sema.db);
         let file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
 
-        let rename_changes =
-            rename_with_semantics(sema, file_position, &self.suggested_text).ok()?;
-
         let label = format!("Rename to {}", self.suggested_text);
-        Some(Fix::new(&label, rename_changes, frange.range))
+        let mut res = unresolved_fix("change_case", &label, frange.range);
+        if resolve {
+            let source_change = rename_with_semantics(sema, file_position, &self.suggested_text);
+            res.source_change = Some(source_change.ok().unwrap_or_default());
+        }
+
+        Some(res)
     }
 }
 
 impl DiagnosticWithFix for ReplaceFilterMapNextWithFindMap {
-    fn fix(&self, sema: &Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         let root = sema.db.parse_or_expand(self.file)?;
         let next_expr = self.next_expr.to_node(&root);
         let next_call = ast::MethodCallExpr::cast(next_expr.syntax().clone())?;
@@ -163,7 +177,8 @@ impl DiagnosticWithFix for ReplaceFilterMapNextWithFindMap {
 
         let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
 
-        Some(Fix::new(
+        Some(fix(
+            "replace_with_find_map",
             "Replace filter_map(..).next() with find_map()",
             source_change,
             trigger_range,
@@ -175,7 +190,7 @@ fn missing_record_expr_field_fix(
     sema: &Semantics<RootDatabase>,
     usage_file_id: FileId,
     record_expr_field: &ast::RecordExprField,
-) -> Option<Fix> {
+) -> Option<Assist> {
     let record_lit = ast::RecordExpr::cast(record_expr_field.syntax().parent()?.parent()?)?;
     let def_id = sema.resolve_variant(record_lit)?;
     let module;
@@ -233,7 +248,12 @@ fn missing_record_expr_field_fix(
         def_file_id,
         TextEdit::insert(last_field_syntax.text_range().end(), new_field),
     );
-    return Some(Fix::new("Create field", source_change, record_expr_field.syntax().text_range()));
+    return Some(fix(
+        "create_field",
+        "Create field",
+        source_change,
+        record_expr_field.syntax().text_range(),
+    ));
 
     fn record_field_list(field_def_list: ast::FieldList) -> Option<ast::RecordFieldList> {
         match field_def_list {
diff --git a/crates/ide/src/diagnostics/unlinked_file.rs b/crates/ide/src/diagnostics/unlinked_file.rs
index e174fb767..7d39f4fbe 100644
--- a/crates/ide/src/diagnostics/unlinked_file.rs
+++ b/crates/ide/src/diagnostics/unlinked_file.rs
@@ -16,9 +16,10 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::Fix;
-
-use super::fixes::DiagnosticWithFix;
+use crate::{
+    diagnostics::{fix, fixes::DiagnosticWithFix},
+    Assist,
+};
 
 // Diagnostic: unlinked-file
 //
@@ -49,7 +50,7 @@ impl Diagnostic for UnlinkedFile {
 }
 
 impl DiagnosticWithFix for UnlinkedFile {
-    fn fix(&self, sema: &hir::Semantics<RootDatabase>) -> Option<Fix> {
+    fn fix(&self, sema: &hir::Semantics<RootDatabase>, _resolve: bool) -> Option<Assist> {
         // If there's an existing module that could add a `mod` item to include the unlinked file,
         // suggest that as a fix.
 
@@ -100,7 +101,7 @@ fn make_fix(
     parent_file_id: FileId,
     new_mod_name: &str,
     added_file_id: FileId,
-) -> Option<Fix> {
+) -> Option<Assist> {
     fn is_outline_mod(item: &ast::Item) -> bool {
         matches!(item, ast::Item::Module(m) if m.item_list().is_none())
     }
@@ -152,7 +153,8 @@ fn make_fix(
 
     let edit = builder.finish();
     let trigger_range = db.parse(added_file_id).tree().syntax().text_range();
-    Some(Fix::new(
+    Some(fix(
+        "add_mod_declaration",
         &format!("Insert `{}`", mod_decl),
         SourceChange::from_text_edit(parent_file_id, edit),
         trigger_range,
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index d057d5402..a04333e63 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -110,6 +110,13 @@ mod tests {
         assert_eq!(expected, FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() });
     }
 
+    fn check_unresolved(ra_fixture: &str) {
+        let (analysis, position) = fixture::position(ra_fixture);
+        let navs = analysis.goto_definition(position).unwrap().expect("no definition found").info;
+
+        assert!(navs.is_empty(), "didn't expect this to resolve anywhere: {:?}", navs)
+    }
+
     #[test]
     fn goto_def_for_extern_crate() {
         check(
@@ -927,17 +934,12 @@ fn f() -> impl Iterator<Item$0 = u8> {}
     }
 
     #[test]
-    #[should_panic = "unresolved reference"]
     fn unknown_assoc_ty() {
-        check(
+        check_unresolved(
             r#"
-trait Iterator {
-    type Item;
-       //^^^^
-}
-
+trait Iterator { type Item; }
 fn f() -> impl Iterator<Invalid$0 = u8> {}
-            "#,
+"#,
         )
     }
 
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 3f73c0632..b24c664ba 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -69,7 +69,7 @@ use crate::display::ToNav;
 pub use crate::{
     annotations::{Annotation, AnnotationConfig, AnnotationKind},
     call_hierarchy::CallItem,
-    diagnostics::{Diagnostic, DiagnosticsConfig, Fix, Severity},
+    diagnostics::{Diagnostic, DiagnosticsConfig, Severity},
     display::navigation_target::NavigationTarget,
     expand_macro::ExpandedMacro,
     file_structure::{StructureNode, StructureNodeKind},
@@ -82,7 +82,7 @@ pub use crate::{
     references::{rename::RenameError, ReferenceSearchResult},
     runnables::{Runnable, RunnableKind, TestId},
     syntax_highlighting::{
-        tags::{Highlight, HlMod, HlMods, HlPunct, HlTag},
+        tags::{Highlight, HlMod, HlMods, HlOperator, HlPunct, HlTag},
         HlRange,
     },
 };
@@ -526,9 +526,39 @@ impl Analysis {
     pub fn diagnostics(
         &self,
         config: &DiagnosticsConfig,
+        resolve: bool,
         file_id: FileId,
     ) -> Cancelable<Vec<Diagnostic>> {
-        self.with_db(|db| diagnostics::diagnostics(db, config, file_id))
+        self.with_db(|db| diagnostics::diagnostics(db, config, resolve, file_id))
+    }
+
+    /// Convenience function to return assists + quick fixes for diagnostics
+    pub fn assists_with_fixes(
+        &self,
+        assist_config: &AssistConfig,
+        diagnostics_config: &DiagnosticsConfig,
+        resolve: bool,
+        frange: FileRange,
+    ) -> Cancelable<Vec<Assist>> {
+        let include_fixes = match &assist_config.allowed {
+            Some(it) => it.iter().any(|&it| it == AssistKind::None || it == AssistKind::QuickFix),
+            None => true,
+        };
+
+        self.with_db(|db| {
+            let mut res = Assist::get(db, assist_config, resolve, frange);
+            ssr::add_ssr_assist(db, &mut res, resolve, frange);
+
+            if include_fixes {
+                res.extend(
+                    diagnostics::diagnostics(db, diagnostics_config, resolve, frange.file_id)
+                        .into_iter()
+                        .filter_map(|it| it.fix)
+                        .filter(|it| it.target.intersect(frange.range).is_some()),
+                );
+            }
+            res
+        })
     }
 
     /// Returns the edit required to rename reference at the position to the new
diff --git a/crates/ide/src/move_item.rs b/crates/ide/src/move_item.rs
index 8d37f4f92..246f10a0a 100644
--- a/crates/ide/src/move_item.rs
+++ b/crates/ide/src/move_item.rs
@@ -1,4 +1,4 @@
-use std::iter::once;
+use std::{iter::once, mem};
 
 use hir::Semantics;
 use ide_db::{base_db::FileRange, RootDatabase};
@@ -102,7 +102,7 @@ fn move_in_direction(
             ast::GenericArgList(it) => swap_sibling_in_list(node, it.generic_args(), range, direction),
             ast::VariantList(it) => swap_sibling_in_list(node, it.variants(), range, direction),
             ast::TypeBoundList(it) => swap_sibling_in_list(node, it.bounds(), range, direction),
-            _ => Some(replace_nodes(node, &match direction {
+            _ => Some(replace_nodes(range, node, &match direction {
                 Direction::Up => node.prev_sibling(),
                 Direction::Down => node.next_sibling(),
             }?))
@@ -125,7 +125,7 @@ fn swap_sibling_in_list<A: AstNode + Clone, I: Iterator<Item = A>>(
         .next();
 
     if let Some((l, r)) = list_lookup {
-        Some(replace_nodes(l.syntax(), r.syntax()))
+        Some(replace_nodes(range, l.syntax(), r.syntax()))
     } else {
         // Cursor is beyond any movable list item (for example, on curly brace in enum).
         // It's not necessary, that parent of list is movable (arg list's parent is not, for example),
@@ -134,11 +134,38 @@ fn swap_sibling_in_list<A: AstNode + Clone, I: Iterator<Item = A>>(
     }
 }
 
-fn replace_nodes(first: &SyntaxNode, second: &SyntaxNode) -> TextEdit {
+fn replace_nodes<'a>(
+    range: TextRange,
+    mut first: &'a SyntaxNode,
+    mut second: &'a SyntaxNode,
+) -> TextEdit {
+    let cursor_offset = if range.is_empty() {
+        // FIXME: `applySnippetTextEdits` does not support non-empty selection ranges
+        if first.text_range().contains_range(range) {
+            Some(range.start() - first.text_range().start())
+        } else if second.text_range().contains_range(range) {
+            mem::swap(&mut first, &mut second);
+            Some(range.start() - first.text_range().start())
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
+    let first_with_cursor = match cursor_offset {
+        Some(offset) => {
+            let mut item_text = first.text().to_string();
+            item_text.insert_str(offset.into(), "$0");
+            item_text
+        }
+        None => first.text().to_string(),
+    };
+
     let mut edit = TextEditBuilder::default();
 
     algo::diff(first, second).into_text_edit(&mut edit);
-    algo::diff(second, first).into_text_edit(&mut edit);
+    edit.replace(second.text_range(), first_with_cursor);
 
     edit.finish()
 }
@@ -188,7 +215,7 @@ fn main() {
             expect![[r#"
 fn main() {
     match true {
-        false => {
+        false =>$0 {
             println!("Test");
         },
         true => {
@@ -222,7 +249,7 @@ fn main() {
         false => {
             println!("Test");
         },
-        true => {
+        true =>$0 {
             println!("Hello, world");
         }
     };
@@ -274,7 +301,7 @@ fn main() {
             "#,
             expect![[r#"
 fn main() {
-    let test2 = 456;
+    let test2$0 = 456;
     let test = 123;
 }
             "#]],
@@ -293,7 +320,7 @@ fn main() {
             "#,
             expect![[r#"
 fn main() {
-    println!("All I want to say is...");
+    println!("All I want to say is...");$0
     println!("Hello, world");
 }
             "#]],
@@ -313,7 +340,7 @@ fn main() {
 fn main() {
     if true {
         println!("Test");
-    }
+    }$0
 
     println!("Hello, world");
 }
@@ -334,7 +361,7 @@ fn main() {
 fn main() {
     for i in 0..10 {
         println!("Test");
-    }
+    }$0
 
     println!("Hello, world");
 }
@@ -355,7 +382,7 @@ fn main() {
 fn main() {
     loop {
         println!("Test");
-    }
+    }$0
 
     println!("Hello, world");
 }
@@ -376,7 +403,7 @@ fn main() {
 fn main() {
     while true {
         println!("Test");
-    }
+    }$0
 
     println!("Hello, world");
 }
@@ -393,7 +420,7 @@ fn main() {
             "#,
             expect![[r#"
 fn main() {
-    return 123;
+    return 123;$0
 
     println!("Hello, world");
 }
@@ -430,7 +457,7 @@ fn main() {}
 fn foo() {}$0$0
             "#,
             expect![[r#"
-fn foo() {}
+fn foo() {}$0
 
 fn main() {}
             "#]],
@@ -451,7 +478,7 @@ impl Wow for Yay $0$0{}
             expect![[r#"
 struct Yay;
 
-impl Wow for Yay {}
+impl Wow for Yay $0{}
 
 trait Wow {}
             "#]],
@@ -467,7 +494,7 @@ use std::vec::Vec;
 use std::collections::HashMap$0$0;
             "#,
             expect![[r#"
-use std::collections::HashMap;
+use std::collections::HashMap$0;
 use std::vec::Vec;
             "#]],
             Direction::Up,
@@ -502,7 +529,7 @@ fn main() {
     }
 
     #[test]
-    fn test_moves_param_up() {
+    fn test_moves_param() {
         check(
             r#"
 fn test(one: i32, two$0$0: u32) {}
@@ -512,7 +539,7 @@ fn main() {
 }
             "#,
             expect![[r#"
-fn test(two: u32, one: i32) {}
+fn test(two$0: u32, one: i32) {}
 
 fn main() {
     test(123, 456);
@@ -520,6 +547,15 @@ fn main() {
             "#]],
             Direction::Up,
         );
+        check(
+            r#"
+fn f($0$0arg: u8, arg2: u16) {}
+            "#,
+            expect![[r#"
+fn f(arg2: u16, $0arg: u8) {}
+            "#]],
+            Direction::Down,
+        );
     }
 
     #[test]
@@ -536,7 +572,7 @@ fn main() {
 fn test(one: i32, two: u32) {}
 
 fn main() {
-    test(456, 123);
+    test(456$0, 123);
 }
             "#]],
             Direction::Up,
@@ -557,7 +593,7 @@ fn main() {
 fn test(one: i32, two: u32) {}
 
 fn main() {
-    test(456, 123);
+    test(456, 123$0);
 }
             "#]],
             Direction::Down,
@@ -594,7 +630,7 @@ struct Test<A, B$0$0>(A, B);
 fn main() {}
             "#,
             expect![[r#"
-struct Test<B, A>(A, B);
+struct Test<B$0, A>(A, B);
 
 fn main() {}
             "#]],
@@ -616,7 +652,7 @@ fn main() {
 struct Test<A, B>(A, B);
 
 fn main() {
-    let t = Test::<&str, i32>(123, "yay");
+    let t = Test::<&str$0, i32>(123, "yay");
 }
             "#]],
             Direction::Up,
@@ -636,7 +672,7 @@ fn main() {}
             "#,
             expect![[r#"
 enum Hello {
-    Two,
+    Two$0,
     One
 }
 
@@ -663,7 +699,7 @@ trait One {}
 
 trait Two {}
 
-fn test<T: Two + One>(t: T) {}
+fn test<T: Two$0 + One>(t: T) {}
 
 fn main() {}
             "#]],
@@ -709,7 +745,7 @@ trait Yay {
 impl Yay for Test {
     type One = i32;
 
-    fn inner() {
+    fn inner() {$0
         println!("Mmmm");
     }
 
@@ -736,7 +772,7 @@ fn test() {
             "#,
             expect![[r#"
 fn test() {
-    mod hi {
+    mod hi {$0
         fn inner() {}
     }
 
@@ -764,7 +800,7 @@ fn main() {}
             expect![[r#"
 fn main() {}
 
-#[derive(Debug)]
+$0#[derive(Debug)]
 enum FooBar {
     Foo,
     Bar,
@@ -784,7 +820,7 @@ fn main() {}
             expect![[r#"
 fn main() {}
 
-enum FooBar {
+$0enum FooBar {
     Foo,
     Bar,
 }
@@ -804,7 +840,7 @@ fn main() {}
             expect![[r#"
 struct Test;
 
-impl SomeTrait for Test {}
+$0impl SomeTrait for Test {}
 
 trait SomeTrait {}
 
@@ -831,7 +867,7 @@ fn main() {}
 enum FooBar {
     Foo,
     Bar,
-}
+}$0
             "#]],
             Direction::Down,
         );
@@ -848,7 +884,7 @@ fn main() {}
             expect![[r#"
 struct Test;
 
-impl SomeTrait for Test {}
+impl SomeTrait for Test {}$0
 
 trait SomeTrait {}
 
diff --git a/crates/ide/src/syntax_highlighting/highlight.rs b/crates/ide/src/syntax_highlighting/highlight.rs
index e921784bf..8cc877c1c 100644
--- a/crates/ide/src/syntax_highlighting/highlight.rs
+++ b/crates/ide/src/syntax_highlighting/highlight.rs
@@ -12,7 +12,10 @@ use syntax::{
     SyntaxNode, SyntaxToken, T,
 };
 
-use crate::{syntax_highlighting::tags::HlPunct, Highlight, HlMod, HlTag};
+use crate::{
+    syntax_highlighting::tags::{HlOperator, HlPunct},
+    Highlight, HlMod, HlTag,
+};
 
 pub(super) fn element(
     sema: &Semantics<RootDatabase>,
@@ -132,7 +135,7 @@ pub(super) fn element(
         INT_NUMBER | FLOAT_NUMBER => HlTag::NumericLiteral.into(),
         BYTE => HlTag::ByteLiteral.into(),
         CHAR => HlTag::CharLiteral.into(),
-        QUESTION => Highlight::new(HlTag::Operator) | HlMod::ControlFlow,
+        QUESTION => Highlight::new(HlTag::Operator(HlOperator::Other)) | HlMod::ControlFlow,
         LIFETIME => {
             let lifetime = element.into_node().and_then(ast::Lifetime::cast).unwrap();
 
@@ -146,8 +149,11 @@ pub(super) fn element(
             }
         }
         p if p.is_punct() => match p {
+            T![&] if element.parent().and_then(ast::BinExpr::cast).is_some() => {
+                HlTag::Operator(HlOperator::Bitwise).into()
+            }
             T![&] => {
-                let h = HlTag::Operator.into();
+                let h = HlTag::Operator(HlOperator::Other).into();
                 let is_unsafe = element
                     .parent()
                     .and_then(ast::RefExpr::cast)
@@ -159,13 +165,18 @@ pub(super) fn element(
                     h
                 }
             }
-            T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => HlTag::Operator.into(),
+            T![::] | T![->] | T![=>] | T![..] | T![=] | T![@] | T![.] => {
+                HlTag::Operator(HlOperator::Other).into()
+            }
             T![!] if element.parent().and_then(ast::MacroCall::cast).is_some() => {
                 HlTag::Symbol(SymbolKind::Macro).into()
             }
             T![!] if element.parent().and_then(ast::NeverType::cast).is_some() => {
                 HlTag::BuiltinType.into()
             }
+            T![!] if element.parent().and_then(ast::PrefixExpr::cast).is_some() => {
+                HlTag::Operator(HlOperator::Logical).into()
+            }
             T![*] if element.parent().and_then(ast::PtrType::cast).is_some() => {
                 HlTag::Keyword.into()
             }
@@ -175,9 +186,9 @@ pub(super) fn element(
                 let expr = prefix_expr.expr()?;
                 let ty = sema.type_of_expr(&expr)?;
                 if ty.is_raw_ptr() {
-                    HlTag::Operator | HlMod::Unsafe
+                    HlTag::Operator(HlOperator::Other) | HlMod::Unsafe
                 } else if let Some(ast::PrefixOp::Deref) = prefix_expr.op_kind() {
-                    HlTag::Operator.into()
+                    HlTag::Operator(HlOperator::Other).into()
                 } else {
                     HlTag::Punctuation(HlPunct::Other).into()
                 }
@@ -188,19 +199,43 @@ pub(super) fn element(
                 let expr = prefix_expr.expr()?;
                 match expr {
                     ast::Expr::Literal(_) => HlTag::NumericLiteral,
-                    _ => HlTag::Operator,
+                    _ => HlTag::Operator(HlOperator::Other),
                 }
                 .into()
             }
             _ if element.parent().and_then(ast::PrefixExpr::cast).is_some() => {
-                HlTag::Operator.into()
+                HlTag::Operator(HlOperator::Other).into()
+            }
+            T![+] | T![-] | T![*] | T![/] | T![+=] | T![-=] | T![*=] | T![/=]
+                if element.parent().and_then(ast::BinExpr::cast).is_some() =>
+            {
+                HlTag::Operator(HlOperator::Arithmetic).into()
+            }
+            T![|] | T![&] | T![!] | T![^] | T![|=] | T![&=] | T![^=]
+                if element.parent().and_then(ast::BinExpr::cast).is_some() =>
+            {
+                HlTag::Operator(HlOperator::Bitwise).into()
+            }
+            T![&&] | T![||] if element.parent().and_then(ast::BinExpr::cast).is_some() => {
+                HlTag::Operator(HlOperator::Logical).into()
+            }
+            T![>] | T![<] | T![==] | T![>=] | T![<=] | T![!=]
+                if element.parent().and_then(ast::BinExpr::cast).is_some() =>
+            {
+                HlTag::Operator(HlOperator::Comparision).into()
+            }
+            _ if element.parent().and_then(ast::BinExpr::cast).is_some() => {
+                HlTag::Operator(HlOperator::Other).into()
             }
-            _ if element.parent().and_then(ast::BinExpr::cast).is_some() => HlTag::Operator.into(),
             _ if element.parent().and_then(ast::RangeExpr::cast).is_some() => {
-                HlTag::Operator.into()
+                HlTag::Operator(HlOperator::Other).into()
+            }
+            _ if element.parent().and_then(ast::RangePat::cast).is_some() => {
+                HlTag::Operator(HlOperator::Other).into()
+            }
+            _ if element.parent().and_then(ast::RestPat::cast).is_some() => {
+                HlTag::Operator(HlOperator::Other).into()
             }
-            _ if element.parent().and_then(ast::RangePat::cast).is_some() => HlTag::Operator.into(),
-            _ if element.parent().and_then(ast::RestPat::cast).is_some() => HlTag::Operator.into(),
             _ if element.parent().and_then(ast::Attr::cast).is_some() => HlTag::Attribute.into(),
             kind => HlTag::Punctuation(match kind {
                 T!['['] | T![']'] => HlPunct::Bracket,
diff --git a/crates/ide/src/syntax_highlighting/inject.rs b/crates/ide/src/syntax_highlighting/inject.rs
index 04fafd244..855c7fba8 100644
--- a/crates/ide/src/syntax_highlighting/inject.rs
+++ b/crates/ide/src/syntax_highlighting/inject.rs
@@ -90,6 +90,13 @@ const RUSTDOC_FENCE_TOKENS: &[&'static str] = &[
     "edition2021",
 ];
 
+fn is_rustdoc_fence_token(token: &str) -> bool {
+    if RUSTDOC_FENCE_TOKENS.contains(&token) {
+        return true;
+    }
+    token.starts_with('E') && token.len() == 5 && token[1..].parse::<u32>().is_ok()
+}
+
 /// Injection of syntax highlighting of doctests.
 pub(super) fn doc_comment(
     hl: &mut Highlights,
@@ -174,8 +181,7 @@ pub(super) fn doc_comment(
                     is_codeblock = !is_codeblock;
                     // Check whether code is rust by inspecting fence guards
                     let guards = &line[idx + RUSTDOC_FENCE.len()..];
-                    let is_rust =
-                        guards.split(',').all(|sub| RUSTDOC_FENCE_TOKENS.contains(&sub.trim()));
+                    let is_rust = guards.split(',').all(|sub| is_rustdoc_fence_token(sub.trim()));
                     is_doctest = is_codeblock && is_rust;
                     continue;
                 }
diff --git a/crates/ide/src/syntax_highlighting/tags.rs b/crates/ide/src/syntax_highlighting/tags.rs
index 1cec991aa..8128d231d 100644
--- a/crates/ide/src/syntax_highlighting/tags.rs
+++ b/crates/ide/src/syntax_highlighting/tags.rs
@@ -28,7 +28,7 @@ pub enum HlTag {
     FormatSpecifier,
     Keyword,
     NumericLiteral,
-    Operator,
+    Operator(HlOperator),
     Punctuation(HlPunct),
     StringLiteral,
     UnresolvedReference,
@@ -87,6 +87,20 @@ pub enum HlPunct {
     Other,
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum HlOperator {
+    /// |, &, !, ^, |=, &=, ^=
+    Bitwise,
+    /// +, -, *, /, +=, -=, *=, /=
+    Arithmetic,
+    /// &&, ||, !
+    Logical,
+    /// >, <, ==, >=, <=, !=
+    Comparision,
+    ///
+    Other,
+}
+
 impl HlTag {
     fn as_str(self) -> &'static str {
         match self {
@@ -133,7 +147,13 @@ impl HlTag {
                 HlPunct::Other => "punctuation",
             },
             HlTag::NumericLiteral => "numeric_literal",
-            HlTag::Operator => "operator",
+            HlTag::Operator(op) => match op {
+                HlOperator::Bitwise => "bitwise",
+                HlOperator::Arithmetic => "arithmetic",
+                HlOperator::Logical => "logical",
+                HlOperator::Comparision => "comparision",
+                HlOperator::Other => "operator",
+            },
             HlTag::StringLiteral => "string_literal",
             HlTag::UnresolvedReference => "unresolved_reference",
             HlTag::None => "none",
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 b6d1cac4e..6ee6d85fb 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlight_doctest.html
@@ -76,7 +76,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="comment documentation">/// </span><span class="comment injected">// calls bar on foo</span>
     <span class="comment documentation">/// </span><span class="macro injected">assert!</span><span class="parenthesis injected">(</span><span class="none injected">foo</span><span class="operator injected">.</span><span class="none injected">bar</span><span class="parenthesis injected">(</span><span class="parenthesis injected">)</span><span class="parenthesis injected">)</span><span class="semicolon injected">;</span>
     <span class="comment documentation">///</span>
-    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="none injected"> </span><span class="variable declaration injected">bar</span><span class="none injected"> </span><span class="operator injected">=</span><span class="none injected"> </span><span class="variable injected">foo</span><span class="operator injected">.</span><span class="field injected">bar</span><span class="none injected"> </span><span class="operator injected">||</span><span class="none injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="constant injected">bar</span><span class="semicolon injected">;</span>
+    <span class="comment documentation">/// </span><span class="keyword injected">let</span><span class="none injected"> </span><span class="variable declaration injected">bar</span><span class="none injected"> </span><span class="operator injected">=</span><span class="none injected"> </span><span class="variable injected">foo</span><span class="operator injected">.</span><span class="field injected">bar</span><span class="none injected"> </span><span class="logical injected">||</span><span class="none injected"> </span><span class="struct injected">Foo</span><span class="operator injected">::</span><span class="constant injected">bar</span><span class="semicolon injected">;</span>
     <span class="comment documentation">///</span>
     <span class="comment documentation">/// </span><span class="comment injected">/* multi-line</span>
     <span class="comment documentation">/// </span><span class="comment injected">       comment */</span>
diff --git a/crates/ide/src/syntax_highlighting/test_data/highlighting.html b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
index 973173254..c43bcb691 100644
--- a/crates/ide/src/syntax_highlighting/test_data/highlighting.html
+++ b/crates/ide/src/syntax_highlighting/test_data/highlighting.html
@@ -213,7 +213,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="keyword">let</span> <span class="variable declaration">baz</span> <span class="operator">=</span> <span class="numeric_literal">-</span><span class="numeric_literal">42</span><span class="semicolon">;</span>
     <span class="keyword">let</span> <span class="variable declaration">baz</span> <span class="operator">=</span> <span class="operator">-</span><span class="variable">baz</span><span class="semicolon">;</span>
 
-    <span class="keyword">let</span> <span class="punctuation">_</span> <span class="operator">=</span> <span class="operator">!</span><span class="bool_literal">true</span><span class="semicolon">;</span>
+    <span class="keyword">let</span> <span class="punctuation">_</span> <span class="operator">=</span> <span class="logical">!</span><span class="bool_literal">true</span><span class="semicolon">;</span>
 
     <span class="label declaration">'foo</span><span class="colon">:</span> <span class="keyword control">loop</span> <span class="brace">{</span>
         <span class="keyword control">break</span> <span class="label">'foo</span><span class="semicolon">;</span>
diff --git a/crates/ide/src/syntax_highlighting/tests.rs b/crates/ide/src/syntax_highlighting/tests.rs
index de2d22ac7..933cfa6f3 100644
--- a/crates/ide/src/syntax_highlighting/tests.rs
+++ b/crates/ide/src/syntax_highlighting/tests.rs
@@ -2,8 +2,7 @@ use std::time::Instant;
 
 use expect_test::{expect_file, ExpectFile};
 use ide_db::SymbolKind;
-use stdx::format_to;
-use test_utils::{bench, bench_fixture, skip_slow_tests};
+use test_utils::{bench, bench_fixture, skip_slow_tests, AssertLinear};
 
 use crate::{fixture, FileRange, HlTag, TextRange};
 
@@ -266,90 +265,27 @@ fn syntax_highlighting_not_quadratic() {
         return;
     }
 
-    let mut measures = Vec::new();
-    for i in 6..=10 {
-        let n = 1 << i;
-        let fixture = bench_fixture::big_struct_n(n);
-        let (analysis, file_id) = fixture::file(&fixture);
+    let mut al = AssertLinear::default();
+    while al.next_round() {
+        for i in 6..=10 {
+            let n = 1 << i;
 
-        let time = Instant::now();
+            let fixture = bench_fixture::big_struct_n(n);
+            let (analysis, file_id) = fixture::file(&fixture);
 
-        let hash = analysis
-            .highlight(file_id)
-            .unwrap()
-            .iter()
-            .filter(|it| it.highlight.tag == HlTag::Symbol(SymbolKind::Struct))
-            .count();
-        assert!(hash > n as usize);
+            let time = Instant::now();
 
-        let elapsed = time.elapsed();
-        measures.push((n as f64, elapsed.as_millis() as f64))
-    }
+            let hash = analysis
+                .highlight(file_id)
+                .unwrap()
+                .iter()
+                .filter(|it| it.highlight.tag == HlTag::Symbol(SymbolKind::Struct))
+                .count();
+            assert!(hash > n as usize);
 
-    assert_linear(&measures)
-}
-
-/// Checks that a set of measurements looks like a liner function rather than
-/// like a quadratic function. Algorithm:
-///
-/// 1. Linearly scale input to be in [0; 1)
-/// 2. Using linear regression, compute the best linear function approximating
-///    the input.
-/// 3. Compute RMSE and  maximal absolute error.
-/// 4. Check that errors are within tolerances and that the constant term is not
-///    too negative.
-///
-/// Ideally, we should use a proper "model selection" to directly compare
-/// quadratic and linear models, but that sounds rather complicated:
-///
-///     https://stats.stackexchange.com/questions/21844/selecting-best-model-based-on-linear-quadratic-and-cubic-fit-of-data
-fn assert_linear(xy: &[(f64, f64)]) {
-    let (mut xs, mut ys): (Vec<_>, Vec<_>) = xy.iter().copied().unzip();
-    normalize(&mut xs);
-    normalize(&mut ys);
-    let xy = xs.iter().copied().zip(ys.iter().copied());
-
-    // Linear regression: finding a and b to fit y = a + b*x.
-
-    let mean_x = mean(&xs);
-    let mean_y = mean(&ys);
-
-    let b = {
-        let mut num = 0.0;
-        let mut denom = 0.0;
-        for (x, y) in xy.clone() {
-            num += (x - mean_x) * (y - mean_y);
-            denom += (x - mean_x).powi(2);
+            let elapsed = time.elapsed();
+            al.sample(n as f64, elapsed.as_millis() as f64);
         }
-        num / denom
-    };
-
-    let a = mean_y - b * mean_x;
-
-    let mut plot = format!("y_pred = {:.3} + {:.3} * x\n\nx     y     y_pred\n", a, b);
-
-    let mut se = 0.0;
-    let mut max_error = 0.0f64;
-    for (x, y) in xy {
-        let y_pred = a + b * x;
-        se += (y - y_pred).powi(2);
-        max_error = max_error.max((y_pred - y).abs());
-
-        format_to!(plot, "{:.3} {:.3} {:.3}\n", x, y, y_pred);
-    }
-
-    let rmse = (se / xs.len() as f64).sqrt();
-    format_to!(plot, "\nrmse = {:.3} max error = {:.3}", rmse, max_error);
-
-    assert!(rmse < 0.05 && max_error < 0.1 && a > -0.1, "\nLooks quadratic\n{}", plot);
-
-    fn normalize(xs: &mut Vec<f64>) {
-        let max = xs.iter().copied().max_by(|a, b| a.partial_cmp(b).unwrap()).unwrap();
-        xs.iter_mut().for_each(|it| *it /= max);
-    }
-
-    fn mean(xs: &[f64]) -> f64 {
-        xs.iter().copied().sum::<f64>() / (xs.len() as f64)
     }
 }
 
diff --git a/crates/ide/src/typing.rs b/crates/ide/src/typing.rs
index 1378048e5..82c732390 100644
--- a/crates/ide/src/typing.rs
+++ b/crates/ide/src/typing.rs
@@ -222,8 +222,8 @@ mod tests {
         assert_eq_text!(ra_fixture_after, &actual);
     }
 
-    fn type_char_noop(char_typed: char, before: &str) {
-        let file_change = do_type_char(char_typed, before);
+    fn type_char_noop(char_typed: char, ra_fixture_before: &str) {
+        let file_change = do_type_char(char_typed, ra_fixture_before);
         assert!(file_change.is_none())
     }
 
@@ -240,16 +240,16 @@ mod tests {
         // ");
         type_char(
             '=',
-            r"
+            r#"
 fn foo() {
     let foo $0 1 + 1
 }
-",
-            r"
+"#,
+            r#"
 fn foo() {
     let foo = 1 + 1;
 }
-",
+"#,
         );
         //     do_check(r"
         // fn foo() {
@@ -268,27 +268,27 @@ fn foo() {
     fn indents_new_chain_call() {
         type_char(
             '.',
-            r"
-            fn main() {
-                xs.foo()
-                $0
-            }
-            ",
-            r"
-            fn main() {
-                xs.foo()
-                    .
-            }
-            ",
+            r#"
+fn main() {
+    xs.foo()
+    $0
+}
+            "#,
+            r#"
+fn main() {
+    xs.foo()
+        .
+}
+            "#,
         );
         type_char_noop(
             '.',
-            r"
-            fn main() {
-                xs.foo()
-                    $0
-            }
-            ",
+            r#"
+fn main() {
+    xs.foo()
+        $0
+}
+            "#,
         )
     }
 
@@ -297,26 +297,26 @@ fn foo() {
         type_char(
             '.',
             r"
-            fn main() {
-                xs.foo()
-                $0;
-            }
-            ",
-            r"
-            fn main() {
-                xs.foo()
-                    .;
-            }
+fn main() {
+    xs.foo()
+    $0;
+}
             ",
+            r#"
+fn main() {
+    xs.foo()
+        .;
+}
+            "#,
         );
         type_char_noop(
             '.',
-            r"
-            fn main() {
-                xs.foo()
-                    $0;
-            }
-            ",
+            r#"
+fn main() {
+    xs.foo()
+        $0;
+}
+            "#,
         )
     }
 
@@ -345,30 +345,30 @@ fn main() {
     fn indents_continued_chain_call() {
         type_char(
             '.',
-            r"
-            fn main() {
-                xs.foo()
-                    .first()
-                $0
-            }
-            ",
-            r"
-            fn main() {
-                xs.foo()
-                    .first()
-                    .
-            }
-            ",
+            r#"
+fn main() {
+    xs.foo()
+        .first()
+    $0
+}
+            "#,
+            r#"
+fn main() {
+    xs.foo()
+        .first()
+        .
+}
+            "#,
         );
         type_char_noop(
             '.',
-            r"
-            fn main() {
-                xs.foo()
-                    .first()
-                    $0
-            }
-            ",
+            r#"
+fn main() {
+    xs.foo()
+        .first()
+        $0
+}
+            "#,
         );
     }
 
@@ -376,33 +376,33 @@ fn main() {
     fn indents_middle_of_chain_call() {
         type_char(
             '.',
-            r"
-            fn source_impl() {
-                let var = enum_defvariant_list().unwrap()
-                $0
-                    .nth(92)
-                    .unwrap();
-            }
-            ",
-            r"
-            fn source_impl() {
-                let var = enum_defvariant_list().unwrap()
-                    .
-                    .nth(92)
-                    .unwrap();
-            }
-            ",
+            r#"
+fn source_impl() {
+    let var = enum_defvariant_list().unwrap()
+    $0
+        .nth(92)
+        .unwrap();
+}
+            "#,
+            r#"
+fn source_impl() {
+    let var = enum_defvariant_list().unwrap()
+        .
+        .nth(92)
+        .unwrap();
+}
+            "#,
         );
         type_char_noop(
             '.',
-            r"
-            fn source_impl() {
-                let var = enum_defvariant_list().unwrap()
-                    $0
-                    .nth(92)
-                    .unwrap();
-            }
-            ",
+            r#"
+fn source_impl() {
+    let var = enum_defvariant_list().unwrap()
+        $0
+        .nth(92)
+        .unwrap();
+}
+            "#,
         );
     }
 
@@ -410,25 +410,33 @@ fn main() {
     fn dont_indent_freestanding_dot() {
         type_char_noop(
             '.',
-            r"
-            fn main() {
-                $0
-            }
-            ",
+            r#"
+fn main() {
+    $0
+}
+            "#,
         );
         type_char_noop(
             '.',
-            r"
-            fn main() {
-            $0
-            }
-            ",
+            r#"
+fn main() {
+$0
+}
+            "#,
         );
     }
 
     #[test]
     fn adds_space_after_return_type() {
-        type_char('>', "fn foo() -$0{ 92 }", "fn foo() -> { 92 }")
+        type_char(
+            '>',
+            r#"
+fn foo() -$0{ 92 }
+"#,
+            r#"
+fn foo() -> { 92 }
+"#,
+        );
     }
 
     #[test]
diff --git a/crates/ide/src/typing/on_enter.rs b/crates/ide/src/typing/on_enter.rs
index 6f1ce3689..7d2db201a 100644
--- a/crates/ide/src/typing/on_enter.rs
+++ b/crates/ide/src/typing/on_enter.rs
@@ -4,10 +4,11 @@
 use ide_db::base_db::{FilePosition, SourceDatabase};
 use ide_db::RootDatabase;
 use syntax::{
-    ast::{self, AstToken},
+    algo::find_node_at_offset,
+    ast::{self, edit::IndentLevel, AstToken},
     AstNode, SmolStr, SourceFile,
     SyntaxKind::*,
-    SyntaxToken, TextRange, TextSize, TokenAtOffset,
+    SyntaxNode, SyntaxToken, TextRange, TextSize, TokenAtOffset,
 };
 
 use text_edit::TextEdit;
@@ -19,6 +20,7 @@ use text_edit::TextEdit;
 // - kbd:[Enter] inside triple-slash comments automatically inserts `///`
 // - kbd:[Enter] in the middle or after a trailing space in `//` inserts `//`
 // - kbd:[Enter] inside `//!` doc comments automatically inserts `//!`
+// - kbd:[Enter] after `{` indents contents and closing `}` of single-line block
 //
 // This action needs to be assigned to shortcut explicitly.
 //
@@ -38,25 +40,43 @@ use text_edit::TextEdit;
 pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<TextEdit> {
     let parse = db.parse(position.file_id);
     let file = parse.tree();
-    let comment = file
-        .syntax()
-        .token_at_offset(position.offset)
-        .left_biased()
-        .and_then(ast::Comment::cast)?;
+    let token = file.syntax().token_at_offset(position.offset).left_biased()?;
 
+    if let Some(comment) = ast::Comment::cast(token.clone()) {
+        return on_enter_in_comment(&comment, &file, position.offset);
+    }
+
+    if token.kind() == L_CURLY {
+        // Typing enter after the `{` of a block expression, where the `}` is on the same line
+        if let Some(edit) = find_node_at_offset(file.syntax(), position.offset - TextSize::of('{'))
+            .and_then(|block| on_enter_in_block(block, position))
+        {
+            cov_mark::hit!(indent_block_contents);
+            return Some(edit);
+        }
+    }
+
+    None
+}
+
+fn on_enter_in_comment(
+    comment: &ast::Comment,
+    file: &ast::SourceFile,
+    offset: TextSize,
+) -> Option<TextEdit> {
     if comment.kind().shape.is_block() {
         return None;
     }
 
     let prefix = comment.prefix();
     let comment_range = comment.syntax().text_range();
-    if position.offset < comment_range.start() + TextSize::of(prefix) {
+    if offset < comment_range.start() + TextSize::of(prefix) {
         return None;
     }
 
     let mut remove_trailing_whitespace = false;
     // Continuing single-line non-doc comments (like this one :) ) is annoying
-    if prefix == "//" && comment_range.end() == position.offset {
+    if prefix == "//" && comment_range.end() == offset {
         if comment.text().ends_with(' ') {
             cov_mark::hit!(continues_end_of_line_comment_with_space);
             remove_trailing_whitespace = true;
@@ -70,14 +90,42 @@ pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<Text
     let delete = if remove_trailing_whitespace {
         let trimmed_len = comment.text().trim_end().len() as u32;
         let trailing_whitespace_len = comment.text().len() as u32 - trimmed_len;
-        TextRange::new(position.offset - TextSize::from(trailing_whitespace_len), position.offset)
+        TextRange::new(offset - TextSize::from(trailing_whitespace_len), offset)
     } else {
-        TextRange::empty(position.offset)
+        TextRange::empty(offset)
     };
     let edit = TextEdit::replace(delete, inserted);
     Some(edit)
 }
 
+fn on_enter_in_block(block: ast::BlockExpr, position: FilePosition) -> Option<TextEdit> {
+    let contents = block_contents(&block)?;
+
+    if block.syntax().text().contains_char('\n') {
+        return None;
+    }
+
+    let indent = IndentLevel::from_node(block.syntax());
+    let mut edit = TextEdit::insert(position.offset, format!("\n{}$0", indent + 1));
+    edit.union(TextEdit::insert(contents.text_range().end(), format!("\n{}", indent))).ok()?;
+    Some(edit)
+}
+
+fn block_contents(block: &ast::BlockExpr) -> Option<SyntaxNode> {
+    let mut node = block.tail_expr().map(|e| e.syntax().clone());
+
+    for stmt in block.statements() {
+        if node.is_some() {
+            // More than 1 node in the block
+            return None;
+        }
+
+        node = Some(stmt.syntax().clone());
+    }
+
+    node
+}
+
 fn followed_by_comment(comment: &ast::Comment) -> bool {
     let ws = match comment.syntax().next_token().and_then(ast::Whitespace::cast) {
         Some(it) => it,
@@ -296,4 +344,144 @@ fn main() {
 ",
         );
     }
+
+    #[test]
+    fn indents_fn_body_block() {
+        cov_mark::check!(indent_block_contents);
+        do_check(
+            r#"
+fn f() {$0()}
+        "#,
+            r#"
+fn f() {
+    $0()
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn indents_block_expr() {
+        do_check(
+            r#"
+fn f() {
+    let x = {$0()};
+}
+        "#,
+            r#"
+fn f() {
+    let x = {
+        $0()
+    };
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn indents_match_arm() {
+        do_check(
+            r#"
+fn f() {
+    match 6 {
+        1 => {$0f()},
+        _ => (),
+    }
+}
+        "#,
+            r#"
+fn f() {
+    match 6 {
+        1 => {
+            $0f()
+        },
+        _ => (),
+    }
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn indents_block_with_statement() {
+        do_check(
+            r#"
+fn f() {$0a = b}
+        "#,
+            r#"
+fn f() {
+    $0a = b
+}
+        "#,
+        );
+        do_check(
+            r#"
+fn f() {$0fn f() {}}
+        "#,
+            r#"
+fn f() {
+    $0fn f() {}
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn indents_nested_blocks() {
+        do_check(
+            r#"
+fn f() {$0{}}
+        "#,
+            r#"
+fn f() {
+    $0{}
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn does_not_indent_empty_block() {
+        do_check_noop(
+            r#"
+fn f() {$0}
+        "#,
+        );
+        do_check_noop(
+            r#"
+fn f() {{$0}}
+        "#,
+        );
+    }
+
+    #[test]
+    fn does_not_indent_block_with_too_much_content() {
+        do_check_noop(
+            r#"
+fn f() {$0 a = b; ()}
+        "#,
+        );
+        do_check_noop(
+            r#"
+fn f() {$0 a = b; a = b; }
+        "#,
+        );
+    }
+
+    #[test]
+    fn does_not_indent_multiline_block() {
+        do_check_noop(
+            r#"
+fn f() {$0
+}
+        "#,
+        );
+        do_check_noop(
+            r#"
+fn f() {$0
+
+}
+        "#,
+        );
+    }
 }