46 files changed, 1085 insertions, 132 deletions

diff --git a/crates/ra_assists/src/assist_context.rs b/crates/ra_assists/src/assist_context.rs
index 3407df856..afd3fd4b9 100644
--- a/crates/ra_assists/src/assist_context.rs
+++ b/crates/ra_assists/src/assist_context.rs
@@ -73,6 +73,10 @@ impl<'a> AssistContext<'a> {
         self.sema.db
     }
 
+    pub(crate) fn source_file(&self) -> &SourceFile {
+        &self.source_file
+    }
+
     // NB, this ignores active selection.
     pub(crate) fn offset(&self) -> TextSize {
         self.frange.range.start()
diff --git a/crates/ra_assists/src/ast_transform.rs b/crates/ra_assists/src/ast_transform.rs
index 28f3f3546..15ec75c95 100644
--- a/crates/ra_assists/src/ast_transform.rs
+++ b/crates/ra_assists/src/ast_transform.rs
@@ -63,7 +63,7 @@ impl<'a> SubstituteTypeParams<'a> {
                     let default = k.default(source_scope.db)?;
                     Some((
                         k,
-                        ast::make::type_ref(
+                        ast::make::ty(
                             &default
                                 .display_source_code(source_scope.db, source_scope.module()?.into())
                                 .ok()?,
diff --git a/crates/ra_assists/src/handlers/early_return.rs b/crates/ra_assists/src/handlers/early_return.rs
index 69852b611..6816a2709 100644
--- a/crates/ra_assists/src/handlers/early_return.rs
+++ b/crates/ra_assists/src/handlers/early_return.rs
@@ -123,7 +123,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                         let happy_arm = {
                             let pat = make::tuple_struct_pat(
                                 path,
-                                once(make::bind_pat(make::name("it")).into()),
+                                once(make::ident_pat(make::name("it")).into()),
                             );
                             let expr = {
                                 let name_ref = make::name_ref("it");
@@ -136,7 +136,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
 
                         let sad_arm = make::match_arm(
                             // FIXME: would be cool to use `None` or `Err(_)` if appropriate
-                            once(make::placeholder_pat().into()),
+                            once(make::wildcard_pat().into()),
                             early_expression,
                         );
 
@@ -144,7 +144,7 @@ pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext)
                     };
 
                     let let_stmt = make::let_stmt(
-                        make::bind_pat(make::name(&bound_ident.syntax().to_string())).into(),
+                        make::ident_pat(make::name(&bound_ident.syntax().to_string())).into(),
                         Some(match_expr),
                     );
                     let let_stmt = let_stmt.indent(if_indent_level);
diff --git a/crates/ra_assists/src/handlers/expand_glob_import.rs b/crates/ra_assists/src/handlers/expand_glob_import.rs
new file mode 100644
index 000000000..eb216a81a
--- /dev/null
+++ b/crates/ra_assists/src/handlers/expand_glob_import.rs
@@ -0,0 +1,391 @@
+use hir::{AssocItem, MacroDef, ModuleDef, Name, PathResolution, ScopeDef, SemanticsScope};
+use ra_ide_db::{
+    defs::{classify_name_ref, Definition, NameRefClass},
+    RootDatabase,
+};
+use ra_syntax::{algo, ast, match_ast, AstNode, SyntaxNode, SyntaxToken, T};
+
+use crate::{
+    assist_context::{AssistBuilder, AssistContext, Assists},
+    AssistId, AssistKind,
+};
+
+use either::Either;
+
+// Assist: expand_glob_import
+//
+// Expands glob imports.
+//
+// ```
+// mod foo {
+//     pub struct Bar;
+//     pub struct Baz;
+// }
+//
+// use foo::*<|>;
+//
+// fn qux(bar: Bar, baz: Baz) {}
+// ```
+// ->
+// ```
+// mod foo {
+//     pub struct Bar;
+//     pub struct Baz;
+// }
+//
+// use foo::{Baz, Bar};
+//
+// fn qux(bar: Bar, baz: Baz) {}
+// ```
+pub(crate) fn expand_glob_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let star = ctx.find_token_at_offset(T![*])?;
+    let mod_path = find_mod_path(&star)?;
+
+    let source_file = ctx.source_file();
+    let scope = ctx.sema.scope_at_offset(source_file.syntax(), ctx.offset());
+
+    let defs_in_mod = find_defs_in_mod(ctx, scope, &mod_path)?;
+    let name_refs_in_source_file =
+        source_file.syntax().descendants().filter_map(ast::NameRef::cast).collect();
+    let used_names = find_used_names(ctx, defs_in_mod, name_refs_in_source_file);
+
+    let parent = star.parent().parent()?;
+    acc.add(
+        AssistId("expand_glob_import", AssistKind::RefactorRewrite),
+        "Expand glob import",
+        parent.text_range(),
+        |builder| {
+            replace_ast(builder, &parent, mod_path, used_names);
+        },
+    )
+}
+
+fn find_mod_path(star: &SyntaxToken) -> Option<ast::Path> {
+    star.ancestors().find_map(|n| ast::UseTree::cast(n).and_then(|u| u.path()))
+}
+
+#[derive(PartialEq)]
+enum Def {
+    ModuleDef(ModuleDef),
+    MacroDef(MacroDef),
+}
+
+impl Def {
+    fn name(&self, db: &RootDatabase) -> Option<Name> {
+        match self {
+            Def::ModuleDef(def) => def.name(db),
+            Def::MacroDef(def) => def.name(db),
+        }
+    }
+}
+
+fn find_defs_in_mod(
+    ctx: &AssistContext,
+    from: SemanticsScope<'_>,
+    path: &ast::Path,
+) -> Option<Vec<Def>> {
+    let hir_path = ctx.sema.lower_path(&path)?;
+    let module = if let Some(PathResolution::Def(ModuleDef::Module(module))) =
+        from.resolve_hir_path_qualifier(&hir_path)
+    {
+        module
+    } else {
+        return None;
+    };
+
+    let module_scope = module.scope(ctx.db(), from.module());
+
+    let mut defs = vec![];
+    for (_, def) in module_scope {
+        match def {
+            ScopeDef::ModuleDef(def) => defs.push(Def::ModuleDef(def)),
+            ScopeDef::MacroDef(def) => defs.push(Def::MacroDef(def)),
+            _ => continue,
+        }
+    }
+
+    Some(defs)
+}
+
+fn find_used_names(
+    ctx: &AssistContext,
+    defs_in_mod: Vec<Def>,
+    name_refs_in_source_file: Vec<ast::NameRef>,
+) -> Vec<Name> {
+    let defs_in_source_file = name_refs_in_source_file
+        .iter()
+        .filter_map(|r| classify_name_ref(&ctx.sema, r))
+        .filter_map(|rc| match rc {
+            NameRefClass::Definition(Definition::ModuleDef(def)) => Some(Def::ModuleDef(def)),
+            NameRefClass::Definition(Definition::Macro(def)) => Some(Def::MacroDef(def)),
+            _ => None,
+        })
+        .collect::<Vec<Def>>();
+
+    defs_in_mod
+        .iter()
+        .filter(|def| {
+            if let Def::ModuleDef(ModuleDef::Trait(tr)) = def {
+                for item in tr.items(ctx.db()) {
+                    if let AssocItem::Function(f) = item {
+                        if defs_in_source_file.contains(&Def::ModuleDef(ModuleDef::Function(f))) {
+                            return true;
+                        }
+                    }
+                }
+            }
+
+            defs_in_source_file.contains(def)
+        })
+        .filter_map(|d| d.name(ctx.db()))
+        .collect()
+}
+
+fn replace_ast(
+    builder: &mut AssistBuilder,
+    node: &SyntaxNode,
+    path: ast::Path,
+    used_names: Vec<Name>,
+) {
+    let replacement: Either<ast::UseTree, ast::UseTreeList> = match used_names.as_slice() {
+        [name] => Either::Left(ast::make::use_tree(
+            ast::make::path_from_text(&format!("{}::{}", path, name)),
+            None,
+            None,
+            false,
+        )),
+        names => Either::Right(ast::make::use_tree_list(names.iter().map(|n| {
+            ast::make::use_tree(ast::make::path_from_text(&n.to_string()), None, None, false)
+        }))),
+    };
+
+    let mut replace_node = |replacement: Either<ast::UseTree, ast::UseTreeList>| {
+        algo::diff(node, &replacement.either(|u| u.syntax().clone(), |ut| ut.syntax().clone()))
+            .into_text_edit(builder.text_edit_builder());
+    };
+
+    match_ast! {
+        match node {
+            ast::UseTree(use_tree) => {
+                replace_node(replacement);
+            },
+            ast::UseTreeList(use_tree_list) => {
+                replace_node(replacement);
+            },
+            ast::Use(use_item) => {
+                builder.replace_ast(use_item, ast::make::use_(replacement.left_or_else(|ut| ast::make::use_tree(path, Some(ut), None, false))));
+            },
+            _ => {},
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn expanding_glob_import() {
+        check_assist(
+            expand_glob_import,
+            r"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+    pub struct Qux;
+
+    pub fn f() {}
+}
+
+use foo::*<|>;
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+}
+",
+            r"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+    pub struct Qux;
+
+    pub fn f() {}
+}
+
+use foo::{Baz, Bar, f};
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+}
+",
+        )
+    }
+
+    #[test]
+    fn expanding_glob_import_with_existing_explicit_names() {
+        check_assist(
+            expand_glob_import,
+            r"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+    pub struct Qux;
+
+    pub fn f() {}
+}
+
+use foo::{*<|>, f};
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+}
+",
+            r"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+    pub struct Qux;
+
+    pub fn f() {}
+}
+
+use foo::{Baz, Bar, f};
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+}
+",
+        )
+    }
+
+    #[test]
+    fn expanding_nested_glob_import() {
+        check_assist(
+            expand_glob_import,
+            r"
+mod foo {
+    mod bar {
+        pub struct Bar;
+        pub struct Baz;
+        pub struct Qux;
+
+        pub fn f() {}
+    }
+
+    mod baz {
+        pub fn g() {}
+    }
+}
+
+use foo::{bar::{*<|>, f}, baz::*};
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+    g();
+}
+",
+            r"
+mod foo {
+    mod bar {
+        pub struct Bar;
+        pub struct Baz;
+        pub struct Qux;
+
+        pub fn f() {}
+    }
+
+    mod baz {
+        pub fn g() {}
+    }
+}
+
+use foo::{bar::{Baz, Bar, f}, baz::*};
+
+fn qux(bar: Bar, baz: Baz) {
+    f();
+    g();
+}
+",
+        )
+    }
+
+    #[test]
+    fn expanding_glob_import_with_macro_defs() {
+        check_assist(
+            expand_glob_import,
+            r"
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! bar {
+    () => ()
+}
+
+pub fn baz() {}
+
+//- /main.rs crate:main deps:foo
+use foo::*<|>;
+
+fn main() {
+    bar!();
+    baz();
+}
+",
+            r"
+use foo::{bar, baz};
+
+fn main() {
+    bar!();
+    baz();
+}
+",
+        )
+    }
+
+    #[test]
+    fn expanding_glob_import_with_trait_method_uses() {
+        check_assist(
+            expand_glob_import,
+            r"
+//- /lib.rs crate:foo
+pub trait Tr {
+    fn method(&self) {}
+}
+impl Tr for () {}
+
+//- /main.rs crate:main deps:foo
+use foo::*<|>;
+
+fn main() {
+    ().method();
+}
+",
+            r"
+use foo::Tr;
+
+fn main() {
+    ().method();
+}
+",
+        )
+    }
+
+    #[test]
+    fn expanding_is_not_applicable_if_cursor_is_not_in_star_token() {
+        check_assist_not_applicable(
+            expand_glob_import,
+            r"
+    mod foo {
+        pub struct Bar;
+        pub struct Baz;
+        pub struct Qux;
+    }
+
+    use foo::Bar<|>;
+
+    fn qux(bar: Bar, baz: Baz) {}
+    ",
+        )
+    }
+}
diff --git a/crates/ra_assists/src/handlers/fill_match_arms.rs b/crates/ra_assists/src/handlers/fill_match_arms.rs
index b2e14f9d7..6698d1a27 100644
--- a/crates/ra_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ra_assists/src/handlers/fill_match_arms.rs
@@ -197,12 +197,11 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> O
     // FIXME: use HIR for this; it doesn't currently expose struct vs. tuple vs. unit variants though
     let pat: ast::Pat = match var.source(db).value.kind() {
         ast::StructKind::Tuple(field_list) => {
-            let pats =
-                iter::repeat(make::placeholder_pat().into()).take(field_list.fields().count());
+            let pats = iter::repeat(make::wildcard_pat().into()).take(field_list.fields().count());
             make::tuple_struct_pat(path, pats).into()
         }
         ast::StructKind::Record(field_list) => {
-            let pats = field_list.fields().map(|f| make::bind_pat(f.name().unwrap()).into());
+            let pats = field_list.fields().map(|f| make::ident_pat(f.name().unwrap()).into());
             make::record_pat(path, pats).into()
         }
         ast::StructKind::Unit => make::path_pat(path),
diff --git a/crates/ra_assists/src/handlers/generate_function.rs b/crates/ra_assists/src/handlers/generate_function.rs
index 56510861d..acc97e648 100644
--- a/crates/ra_assists/src/handlers/generate_function.rs
+++ b/crates/ra_assists/src/handlers/generate_function.rs
@@ -142,7 +142,7 @@ impl FunctionBuilder {
         let fn_body = make::block_expr(vec![], Some(placeholder_expr));
         let visibility = if self.needs_pub { Some(make::visibility_pub_crate()) } else { None };
         let mut fn_def =
-            make::fn_def(visibility, self.fn_name, self.type_params, self.params, fn_body);
+            make::fn_(visibility, self.fn_name, self.type_params, self.params, fn_body);
         let leading_ws;
         let trailing_ws;
 
diff --git a/crates/ra_assists/src/handlers/raw_string.rs b/crates/ra_assists/src/handlers/raw_string.rs
index 4e8a0c2db..4c797178f 100644
--- a/crates/ra_assists/src/handlers/raw_string.rs
+++ b/crates/ra_assists/src/handlers/raw_string.rs
@@ -173,7 +173,7 @@ fn test_required_hashes() {
 }
 
 #[cfg(test)]
-mod test {
+mod tests {
     use test_utils::mark;
 
     use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
diff --git a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
index b7e30a7f2..ecafb74a1 100644
--- a/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_if_let_with_match.rs
@@ -65,7 +65,7 @@ pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext)
                         .type_of_pat(&pat)
                         .and_then(|ty| TryEnum::from_ty(&ctx.sema, &ty))
                         .map(|it| it.sad_pattern())
-                        .unwrap_or_else(|| make::placeholder_pat().into());
+                        .unwrap_or_else(|| make::wildcard_pat().into());
                     let else_expr = unwrap_trivial_block(else_block);
                     make::match_arm(vec![pattern], else_expr)
                 };
diff --git a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
index 64ad15a23..e4d436dec 100644
--- a/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
+++ b/crates/ra_assists/src/handlers/replace_let_with_if_let.rs
@@ -50,10 +50,10 @@ pub(crate) fn replace_let_with_if_let(acc: &mut Assists, ctx: &AssistContext) ->
         target,
         |edit| {
             let with_placeholder: ast::Pat = match happy_variant {
-                None => make::placeholder_pat().into(),
+                None => make::wildcard_pat().into(),
                 Some(var_name) => make::tuple_struct_pat(
                     make::path_unqualified(make::path_segment(make::name_ref(var_name))),
-                    once(make::placeholder_pat().into()),
+                    once(make::wildcard_pat().into()),
                 )
                 .into(),
             };
diff --git a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
index 53496ede1..da0a860c5 100644
--- a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -643,4 +643,46 @@ fn main() {
     ",
         );
     }
+
+    #[test]
+    fn does_not_replace_pub_use() {
+        check_assist(
+            replace_qualified_name_with_use,
+            r"
+pub use std::fmt;
+
+impl std::io<|> for Foo {
+}
+    ",
+            r"
+use std::io;
+
+pub use std::fmt;
+
+impl io for Foo {
+}
+    ",
+        );
+    }
+
+    #[test]
+    fn does_not_replace_pub_crate_use() {
+        check_assist(
+            replace_qualified_name_with_use,
+            r"
+pub(crate) use std::fmt;
+
+impl std::io<|> for Foo {
+}
+    ",
+            r"
+use std::io;
+
+pub(crate) use std::fmt;
+
+impl io for Foo {
+}
+    ",
+        );
+    }
 }
diff --git a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
index e5a4bb23c..d69f2c1b0 100644
--- a/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ra_assists/src/handlers/replace_unwrap_with_match.rs
@@ -52,7 +52,7 @@ pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext)
         target,
         |builder| {
             let ok_path = make::path_unqualified(make::path_segment(make::name_ref(happy_variant)));
-            let it = make::bind_pat(make::name("a")).into();
+            let it = make::ident_pat(make::name("a")).into();
             let ok_tuple = make::tuple_struct_pat(ok_path, iter::once(it)).into();
 
             let bind_path = make::path_unqualified(make::path_segment(make::name_ref("a")));
@@ -60,7 +60,7 @@ pub(crate) fn replace_unwrap_with_match(acc: &mut Assists, ctx: &AssistContext)
 
             let unreachable_call = make::expr_unreachable();
             let err_arm =
-                make::match_arm(iter::once(make::placeholder_pat().into()), unreachable_call);
+                make::match_arm(iter::once(make::wildcard_pat().into()), unreachable_call);
 
             let match_arm_list = make::match_arm_list(vec![ok_arm, err_arm]);
             let match_expr = make::expr_match(caller.clone(), match_arm_list)
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 465b90415..507646cc8 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -140,6 +140,7 @@ mod handlers {
     mod change_return_type_to_result;
     mod change_visibility;
     mod early_return;
+    mod expand_glob_import;
     mod extract_struct_from_enum_variant;
     mod extract_variable;
     mod fill_match_arms;
@@ -181,6 +182,7 @@ mod handlers {
             change_return_type_to_result::change_return_type_to_result,
             change_visibility::change_visibility,
             early_return::convert_to_guarded_return,
+            expand_glob_import::expand_glob_import,
             extract_struct_from_enum_variant::extract_struct_from_enum_variant,
             extract_variable::extract_variable,
             fill_match_arms::fill_match_arms,
diff --git a/crates/ra_assists/src/tests/generated.rs b/crates/ra_assists/src/tests/generated.rs
index eff7feded..97978e7a2 100644
--- a/crates/ra_assists/src/tests/generated.rs
+++ b/crates/ra_assists/src/tests/generated.rs
@@ -229,6 +229,33 @@ fn main() {
 }
 
 #[test]
+fn doctest_expand_glob_import() {
+    check_doc_test(
+        "expand_glob_import",
+        r#####"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+}
+
+use foo::*<|>;
+
+fn qux(bar: Bar, baz: Baz) {}
+"#####,
+        r#####"
+mod foo {
+    pub struct Bar;
+    pub struct Baz;
+}
+
+use foo::{Baz, Bar};
+
+fn qux(bar: Bar, baz: Baz) {}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_extract_struct_from_enum_variant() {
     check_doc_test(
         "extract_struct_from_enum_variant",
diff --git a/crates/ra_assists/src/utils.rs b/crates/ra_assists/src/utils.rs
index 373de273c..54d5678d1 100644
--- a/crates/ra_assists/src/utils.rs
+++ b/crates/ra_assists/src/utils.rs
@@ -181,10 +181,10 @@ impl TryEnum {
         match self {
             TryEnum::Result => make::tuple_struct_pat(
                 make::path_unqualified(make::path_segment(make::name_ref("Err"))),
-                iter::once(make::placeholder_pat().into()),
+                iter::once(make::wildcard_pat().into()),
             )
             .into(),
-            TryEnum::Option => make::bind_pat(make::name("None")).into(),
+            TryEnum::Option => make::ident_pat(make::name("None")).into(),
         }
     }
 
diff --git a/crates/ra_assists/src/utils/insert_use.rs b/crates/ra_assists/src/utils/insert_use.rs
index 617afe2e9..32780fceb 100644
--- a/crates/ra_assists/src/utils/insert_use.rs
+++ b/crates/ra_assists/src/utils/insert_use.rs
@@ -4,7 +4,7 @@
 
 use hir::{self, ModPath};
 use ra_syntax::{
-    ast::{self, NameOwner},
+    ast::{self, NameOwner, VisibilityOwner},
     AstNode, Direction, SmolStr,
     SyntaxKind::{PATH, PATH_SEGMENT},
     SyntaxNode, T,
@@ -378,6 +378,7 @@ fn best_action_for_target(
     let best_action = container
         .children()
         .filter_map(ast::Use::cast)
+        .filter(|u| u.visibility().is_none())
         .filter_map(|it| it.use_tree())
         .map(|u| walk_use_tree_for_best_action(&mut storage, None, u, target))
         .fold(None, |best, a| match best {
diff --git a/crates/ra_db/Cargo.toml b/crates/ra_db/Cargo.toml
index 5f334d04f..fe73dc015 100644
--- a/crates/ra_db/Cargo.toml
+++ b/crates/ra_db/Cargo.toml
@@ -9,7 +9,7 @@ license = "MIT OR Apache-2.0"
 doctest = false
 
 [dependencies]
-salsa = "0.15.0"
+salsa = "0.15.2"
 rustc-hash = "1.1.0"
 
 ra_syntax = { path = "../ra_syntax" }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index a2b9f3e35..07333c453 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -13,14 +13,7 @@ pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, InternEagerExpansionQuery, InternMacroQuery,
     MacroArgTextQuery, MacroDefQuery, MacroExpandQuery, ParseMacroQuery,
 };
-pub use hir_ty::db::{
-    AssociatedTyDataQuery, AssociatedTyValueQuery, CallableItemSignatureQuery, FieldTypesQuery,
-    GenericDefaultsQuery, GenericPredicatesForParamQuery, GenericPredicatesQuery, HirDatabase,
-    HirDatabaseStorage, ImplDatumQuery, ImplSelfTyQuery, ImplTraitQuery, InferQueryQuery,
-    InherentImplsInCrateQuery, InternTypeParamIdQuery, ReturnTypeImplTraitsQuery, StructDatumQuery,
-    TraitDatumQuery, TraitImplsInCrateQuery, TraitImplsInDepsQuery, TraitSolveQuery, TyQuery,
-    ValueTyQuery,
-};
+pub use hir_ty::db::*;
 
 #[test]
 fn hir_database_is_object_safe() {
diff --git a/crates/ra_hir_expand/src/proc_macro.rs b/crates/ra_hir_expand/src/proc_macro.rs
index 04c026004..2c0ec41d2 100644
--- a/crates/ra_hir_expand/src/proc_macro.rs
+++ b/crates/ra_hir_expand/src/proc_macro.rs
@@ -101,7 +101,7 @@ fn remove_derive_attrs(tt: &tt::Subtree) -> Option<tt::Subtree> {
 }
 
 #[cfg(test)]
-mod test {
+mod tests {
     use super::*;
     use test_utils::assert_eq_text;
 
diff --git a/crates/ra_hir_ty/Cargo.toml b/crates/ra_hir_ty/Cargo.toml
index 623ce261a..83397d579 100644
--- a/crates/ra_hir_ty/Cargo.toml
+++ b/crates/ra_hir_ty/Cargo.toml
@@ -28,9 +28,9 @@ test_utils = { path = "../test_utils" }
 
 scoped-tls = "1"
 
-chalk-solve = { version = "0.19.0" }
-chalk-ir = { version = "0.19.0" }
-chalk-recursive = { version = "0.19.0" }
+chalk-solve = { version = "0.21.0" }
+chalk-ir = { version = "0.21.0" }
+chalk-recursive = { version = "0.21.0" }
 
 [dev-dependencies]
 expect = { path = "../expect" }
diff --git a/crates/ra_hir_ty/src/diagnostics/unsafe_check.rs b/crates/ra_hir_ty/src/diagnostics/unsafe_check.rs
index 5cc76bdce..61ffbf5d1 100644
--- a/crates/ra_hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/ra_hir_ty/src/diagnostics/unsafe_check.rs
@@ -6,6 +6,7 @@ use std::sync::Arc;
 use hir_def::{
     body::Body,
     expr::{Expr, ExprId, UnaryOp},
+    resolver::{resolver_for_expr, ResolveValueResult, ValueNs},
     DefWithBodyId,
 };
 use hir_expand::diagnostics::DiagnosticSink;
@@ -70,7 +71,7 @@ pub fn unsafe_expressions(
 ) -> Vec<UnsafeExpr> {
     let mut unsafe_exprs = vec![];
     let body = db.body(def);
-    walk_unsafe(&mut unsafe_exprs, db, infer, &body, body.body_expr, false);
+    walk_unsafe(&mut unsafe_exprs, db, infer, def, &body, body.body_expr, false);
 
     unsafe_exprs
 }
@@ -79,6 +80,7 @@ fn walk_unsafe(
     unsafe_exprs: &mut Vec<UnsafeExpr>,
     db: &dyn HirDatabase,
     infer: &InferenceResult,
+    def: DefWithBodyId,
     body: &Body,
     current: ExprId,
     inside_unsafe_block: bool,
@@ -97,6 +99,15 @@ fn walk_unsafe(
                 }
             }
         }
+        Expr::Path(path) => {
+            let resolver = resolver_for_expr(db.upcast(), def, current);
+            let value_or_partial = resolver.resolve_path_in_value_ns(db.upcast(), path.mod_path());
+            if let Some(ResolveValueResult::ValueNs(ValueNs::StaticId(id))) = value_or_partial {
+                if db.static_data(id).mutable {
+                    unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
+                }
+            }
+        }
         Expr::MethodCall { .. } => {
             if infer
                 .method_resolution(current)
@@ -112,13 +123,13 @@ fn walk_unsafe(
             }
         }
         Expr::Unsafe { body: child } => {
-            return walk_unsafe(unsafe_exprs, db, infer, body, *child, true);
+            return walk_unsafe(unsafe_exprs, db, infer, def, body, *child, true);
         }
         _ => {}
     }
 
     expr.walk_child_exprs(|child| {
-        walk_unsafe(unsafe_exprs, db, infer, body, child, inside_unsafe_block);
+        walk_unsafe(unsafe_exprs, db, infer, def, body, child, inside_unsafe_block);
     });
 }
 
@@ -170,4 +181,25 @@ fn main() {
 "#,
         );
     }
+
+    #[test]
+    fn missing_unsafe_diagnostic_with_static_mut() {
+        check_diagnostics(
+            r#"
+struct Ty {
+    a: u8,
+}
+
+static mut static_mut: Ty = Ty { a: 0 };
+
+fn main() {
+    let x = static_mut.a;
+          //^^^^^^^^^^ This operation is unsafe and requires an unsafe function or block
+    unsafe {
+        let x = static_mut.a;
+    }
+}
+"#,
+        );
+    }
 }
diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 28f32a0a4..3d12039a6 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -440,6 +440,12 @@ impl<'a> InferenceContext<'a> {
                 let ty = self.insert_type_vars(ty.subst(&substs));
                 forbid_unresolved_segments((ty, Some(strukt.into())), unresolved)
             }
+            TypeNs::AdtId(AdtId::UnionId(u)) => {
+                let substs = Ty::substs_from_path(&ctx, path, u.into(), true);
+                let ty = self.db.ty(u.into());
+                let ty = self.insert_type_vars(ty.subst(&substs));
+                forbid_unresolved_segments((ty, Some(u.into())), unresolved)
+            }
             TypeNs::EnumVariantId(var) => {
                 let substs = Ty::substs_from_path(&ctx, path, var.into(), true);
                 let ty = self.db.ty(var.parent.into());
@@ -490,10 +496,7 @@ impl<'a> InferenceContext<'a> {
                 // FIXME potentially resolve assoc type
                 (Ty::Unknown, None)
             }
-            TypeNs::AdtId(AdtId::EnumId(_))
-            | TypeNs::AdtId(AdtId::UnionId(_))
-            | TypeNs::BuiltinType(_)
-            | TypeNs::TraitId(_) => {
+            TypeNs::AdtId(AdtId::EnumId(_)) | TypeNs::BuiltinType(_) | TypeNs::TraitId(_) => {
                 // FIXME diagnostic
                 (Ty::Unknown, None)
             }
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index 1eacc6f95..7638f167b 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -518,6 +518,7 @@ impl Ty {
         let (segment, generic_def) = match resolved {
             ValueTyDefId::FunctionId(it) => (last, Some(it.into())),
             ValueTyDefId::StructId(it) => (last, Some(it.into())),
+            ValueTyDefId::UnionId(it) => (last, Some(it.into())),
             ValueTyDefId::ConstId(it) => (last, Some(it.into())),
             ValueTyDefId::StaticId(_) => (last, None),
             ValueTyDefId::EnumVariantId(var) => {
@@ -1148,11 +1149,12 @@ impl_from!(BuiltinType, AdtId(StructId, EnumId, UnionId), TypeAliasId for TyDefI
 pub enum ValueTyDefId {
     FunctionId(FunctionId),
     StructId(StructId),
+    UnionId(UnionId),
     EnumVariantId(EnumVariantId),
     ConstId(ConstId),
     StaticId(StaticId),
 }
-impl_from!(FunctionId, StructId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
+impl_from!(FunctionId, StructId, UnionId, EnumVariantId, ConstId, StaticId for ValueTyDefId);
 
 /// Build the declared type of an item. This depends on the namespace; e.g. for
 /// `struct Foo(usize)`, we have two types: The type of the struct itself, and
@@ -1179,6 +1181,7 @@ pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Binders
     match def {
         ValueTyDefId::FunctionId(it) => type_for_fn(db, it),
         ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
+        ValueTyDefId::UnionId(it) => type_for_adt(db, it.into()),
         ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
         ValueTyDefId::ConstId(it) => type_for_const(db, it),
         ValueTyDefId::StaticId(it) => type_for_static(db, it),
diff --git a/crates/ra_hir_ty/src/tests/simple.rs b/crates/ra_hir_ty/src/tests/simple.rs
index 3fd7d5cd4..5a7cf9455 100644
--- a/crates/ra_hir_ty/src/tests/simple.rs
+++ b/crates/ra_hir_ty/src/tests/simple.rs
@@ -334,16 +334,44 @@ fn infer_union() {
             bar: f32,
         }
 
+        fn test() {
+            let u = MyUnion { foo: 0 };
+            unsafe { baz(u); }
+            let u = MyUnion { bar: 0.0 };
+            unsafe { baz(u); }
+        }
+
         unsafe fn baz(u: MyUnion) {
             let inner = u.foo;
+            let inner = u.bar;
         }
         "#,
         expect![[r#"
-            61..62 'u': MyUnion
-            73..99 '{     ...foo; }': ()
-            83..88 'inner': u32
-            91..92 'u': MyUnion
-            91..96 'u.foo': u32
+            57..172 '{     ...); } }': ()
+            67..68 'u': MyUnion
+            71..89 'MyUnio...o: 0 }': MyUnion
+            86..87 '0': u32
+            95..113 'unsafe...(u); }': ()
+            102..113 '{ baz(u); }': ()
+            104..107 'baz': fn baz(MyUnion)
+            104..110 'baz(u)': ()
+            108..109 'u': MyUnion
+            122..123 'u': MyUnion
+            126..146 'MyUnio... 0.0 }': MyUnion
+            141..144 '0.0': f32
+            152..170 'unsafe...(u); }': ()
+            159..170 '{ baz(u); }': ()
+            161..164 'baz': fn baz(MyUnion)
+            161..167 'baz(u)': ()
+            165..166 'u': MyUnion
+            188..189 'u': MyUnion
+            200..249 '{     ...bar; }': ()
+            210..215 'inner': u32
+            218..219 'u': MyUnion
+            218..223 'u.foo': u32
+            233..238 'inner': f32
+            241..242 'u': MyUnion
+            241..246 'u.bar': f32
         "#]],
     );
 }
diff --git a/crates/ra_ide/src/diagnostics.rs b/crates/ra_ide/src/diagnostics.rs
index dd8a7ffd9..73c0b8275 100644
--- a/crates/ra_ide/src/diagnostics.rs
+++ b/crates/ra_ide/src/diagnostics.rs
@@ -78,8 +78,10 @@ pub(crate) fn diagnostics(
             } else {
                 let mut field_list = d.ast(db);
                 for f in d.missed_fields.iter() {
-                    let field =
-                        make::record_field(make::name_ref(&f.to_string()), Some(make::expr_unit()));
+                    let field = make::record_expr_field(
+                        make::name_ref(&f.to_string()),
+                        Some(make::expr_unit()),
+                    );
                     field_list = field_list.append_field(&field);
                 }
 
@@ -178,9 +180,9 @@ fn missing_struct_field_fix(
     if new_field_type.is_unknown() {
         return None;
     }
-    let new_field = make::record_field_def(
+    let new_field = make::record_field(
         record_expr.field_name()?,
-        make::type_ref(&new_field_type.display_source_code(sema.db, module.into()).ok()?),
+        make::ty(&new_field_type.display_source_code(sema.db, module.into()).ok()?),
     );
 
     let last_field = record_fields.fields().last()?;
diff --git a/crates/ra_ide/src/folding_ranges.rs b/crates/ra_ide/src/folding_ranges.rs
index 903c34996..0fbc9babd 100644
--- a/crates/ra_ide/src/folding_ranges.rs
+++ b/crates/ra_ide/src/folding_ranges.rs
@@ -85,7 +85,8 @@ fn fold_kind(kind: SyntaxKind) -> Option<FoldKind> {
         COMMENT => Some(FoldKind::Comment),
         USE => Some(FoldKind::Imports),
         ARG_LIST | PARAM_LIST => Some(FoldKind::ArgList),
-        RECORD_FIELD_LIST
+        ASSOC_ITEM_LIST
+        | RECORD_FIELD_LIST
         | RECORD_PAT_FIELD_LIST
         | RECORD_EXPR_FIELD_LIST
         | ITEM_LIST
@@ -337,6 +338,26 @@ fn main() <fold block>{
     }
 
     #[test]
+    fn test_folds_structs() {
+        check(
+            r#"
+struct Foo <fold block>{
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
+    fn test_folds_traits() {
+        check(
+            r#"
+trait Foo <fold block>{
+}</fold>
+"#,
+        );
+    }
+
+    #[test]
     fn test_folds_macros() {
         check(
             r#"
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index aa48cb412..385e3e64e 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -509,6 +509,37 @@ fn main() { }
     }
 
     #[test]
+    fn hover_shows_fn_doc() {
+        check(
+            r#"
+/// # Example
+/// ```
+/// # use std::path::Path;
+/// #
+/// foo(Path::new("hello, world!"))
+/// ```
+pub fn foo<|>(_: &Path) {}
+
+fn main() { }
+"#,
+            expect![[r#"
+                *foo*
+                ```rust
+                pub fn foo(_: &Path)
+                ```
+                ___
+
+                # Example
+                ```
+                # use std::path::Path;
+                #
+                foo(Path::new("hello, world!"))
+                ```
+            "#]],
+        );
+    }
+
+    #[test]
     fn hover_shows_struct_field_info() {
         // Hovering over the field when instantiating
         check(
diff --git a/crates/ra_ide/src/syntax_highlighting.rs b/crates/ra_ide/src/syntax_highlighting.rs
index a32ae0165..f71b804fe 100644
--- a/crates/ra_ide/src/syntax_highlighting.rs
+++ b/crates/ra_ide/src/syntax_highlighting.rs
@@ -4,7 +4,7 @@ mod injection;
 #[cfg(test)]
 mod tests;
 
-use hir::{Name, Semantics};
+use hir::{Name, Semantics, VariantDef};
 use ra_ide_db::{
     defs::{classify_name, classify_name_ref, Definition, NameClass, NameRefClass},
     RootDatabase,
@@ -455,6 +455,18 @@ fn macro_call_range(macro_call: &ast::MacroCall) -> Option<TextRange> {
     Some(TextRange::new(range_start, range_end))
 }
 
+fn is_possibly_unsafe(name_ref: &ast::NameRef) -> bool {
+    name_ref
+        .syntax()
+        .parent()
+        .and_then(|parent| {
+            ast::FieldExpr::cast(parent.clone())
+                .map(|_| true)
+                .or_else(|| ast::RecordPatField::cast(parent).map(|_| true))
+        })
+        .unwrap_or(false)
+}
+
 fn highlight_element(
     sema: &Semantics<RootDatabase>,
     bindings_shadow_count: &mut FxHashMap<Name, u32>,
@@ -484,10 +496,19 @@ fn highlight_element(
 
             match name_kind {
                 Some(NameClass::Definition(def)) => {
-                    highlight_name(db, def) | HighlightModifier::Definition
+                    highlight_name(db, def, false) | HighlightModifier::Definition
+                }
+                Some(NameClass::ConstReference(def)) => highlight_name(db, def, false),
+                Some(NameClass::FieldShorthand { field, .. }) => {
+                    let mut h = HighlightTag::Field.into();
+                    if let Definition::Field(field) = field {
+                        if let VariantDef::Union(_) = field.parent_def(db) {
+                            h |= HighlightModifier::Unsafe;
+                        }
+                    }
+
+                    h
                 }
-                Some(NameClass::ConstReference(def)) => highlight_name(db, def),
-                Some(NameClass::FieldShorthand { .. }) => HighlightTag::Field.into(),
                 None => highlight_name_by_syntax(name) | HighlightModifier::Definition,
             }
         }
@@ -498,6 +519,7 @@ fn highlight_element(
         }
         NAME_REF => {
             let name_ref = element.into_node().and_then(ast::NameRef::cast).unwrap();
+            let possibly_unsafe = is_possibly_unsafe(&name_ref);
             match classify_name_ref(sema, &name_ref) {
                 Some(name_kind) => match name_kind {
                     NameRefClass::Definition(def) => {
@@ -508,11 +530,13 @@ fn highlight_element(
                                 binding_hash = Some(calc_binding_hash(&name, *shadow_count))
                             }
                         };
-                        highlight_name(db, def)
+                        highlight_name(db, def, possibly_unsafe)
                     }
                     NameRefClass::FieldShorthand { .. } => HighlightTag::Field.into(),
                 },
-                None if syntactic_name_ref_highlighting => highlight_name_ref_by_syntax(name_ref),
+                None if syntactic_name_ref_highlighting => {
+                    highlight_name_ref_by_syntax(name_ref, sema)
+                }
                 None => HighlightTag::UnresolvedReference.into(),
             }
         }
@@ -652,10 +676,19 @@ fn is_child_of_impl(element: &SyntaxElement) -> bool {
     }
 }
 
-fn highlight_name(db: &RootDatabase, def: Definition) -> Highlight {
+fn highlight_name(db: &RootDatabase, def: Definition, possibly_unsafe: bool) -> Highlight {
     match def {
         Definition::Macro(_) => HighlightTag::Macro,
-        Definition::Field(_) => HighlightTag::Field,
+        Definition::Field(field) => {
+            let mut h = HighlightTag::Field.into();
+            if possibly_unsafe {
+                if let VariantDef::Union(_) = field.parent_def(db) {
+                    h |= HighlightModifier::Unsafe;
+                }
+            }
+
+            return h;
+        }
         Definition::ModuleDef(def) => match def {
             hir::ModuleDef::Module(_) => HighlightTag::Module,
             hir::ModuleDef::Function(func) => {
@@ -677,6 +710,7 @@ fn highlight_name(db: &RootDatabase, def: Definition) -> Highlight {
                 let mut h = Highlight::new(HighlightTag::Static);
                 if s.is_mut(db) {
                     h |= HighlightModifier::Mutable;
+                    h |= HighlightModifier::Unsafe;
                 }
                 return h;
             }
@@ -724,7 +758,7 @@ fn highlight_name_by_syntax(name: ast::Name) -> Highlight {
     tag.into()
 }
 
-fn highlight_name_ref_by_syntax(name: ast::NameRef) -> Highlight {
+fn highlight_name_ref_by_syntax(name: ast::NameRef, sema: &Semantics<RootDatabase>) -> Highlight {
     let default = HighlightTag::UnresolvedReference;
 
     let parent = match name.syntax().parent() {
@@ -734,7 +768,20 @@ fn highlight_name_ref_by_syntax(name: ast::NameRef) -> Highlight {
 
     let tag = match parent.kind() {
         METHOD_CALL_EXPR => HighlightTag::Function,
-        FIELD_EXPR => HighlightTag::Field,
+        FIELD_EXPR => {
+            let h = HighlightTag::Field;
+            let is_union = ast::FieldExpr::cast(parent)
+                .and_then(|field_expr| {
+                    let field = sema.resolve_field(&field_expr)?;
+                    Some(if let VariantDef::Union(_) = field.parent_def(sema.db) {
+                        true
+                    } else {
+                        false
+                    })
+                })
+                .unwrap_or(false);
+            return if is_union { h | HighlightModifier::Unsafe } else { h.into() };
+        }
         PATH_SEGMENT => {
             let path = match parent.parent().and_then(ast::Path::cast) {
                 Some(it) => it,
diff --git a/crates/ra_ide/src/syntax_highlighting/tests.rs b/crates/ra_ide/src/syntax_highlighting/tests.rs
index 87a6e2523..730efff0d 100644
--- a/crates/ra_ide/src/syntax_highlighting/tests.rs
+++ b/crates/ra_ide/src/syntax_highlighting/tests.rs
@@ -9,6 +9,9 @@ use crate::{mock_analysis::single_file, FileRange, TextRange};
 fn test_highlighting() {
     check_highlighting(
         r#"
+use inner::{self as inner_mod};
+mod inner {}
+
 #[derive(Clone, Debug)]
 struct Foo {
     pub x: i32,
@@ -272,19 +275,37 @@ fn test_unsafe_highlighting() {
         r#"
 unsafe fn unsafe_fn() {}
 
+union Union {
+    a: u32,
+    b: f32,
+}
+
 struct HasUnsafeFn;
 
 impl HasUnsafeFn {
     unsafe fn unsafe_method(&self) {}
 }
 
+struct TypeForStaticMut {
+    a: u8
+}
+
+static mut global_mut: TypeForStaticMut = TypeForStaticMut { a: 0 };
+
 fn main() {
     let x = &5 as *const usize;
+    let u = Union { b: 0 };
     unsafe {
         unsafe_fn();
+        let b = u.b;
+        match u {
+            Union { b: 0 } => (),
+            Union { a } => (),
+        }
         HasUnsafeFn.unsafe_method();
         let y = *(x);
         let z = -x;
+        let a = global_mut.a;
     }
 }
 "#
diff --git a/crates/ra_ide/test_data/highlight_unsafe.html b/crates/ra_ide/test_data/highlight_unsafe.html
index b81b6f1c3..79409fe81 100644
--- a/crates/ra_ide/test_data/highlight_unsafe.html
+++ b/crates/ra_ide/test_data/highlight_unsafe.html
@@ -37,18 +37,36 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 </style>
 <pre><code><span class="keyword unsafe">unsafe</span> <span class="keyword">fn</span> <span class="function declaration unsafe">unsafe_fn</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span><span class="punctuation">}</span>
 
+<span class="keyword">union</span> <span class="union declaration">Union</span> <span class="punctuation">{</span>
+    <span class="field declaration">a</span><span class="punctuation">:</span> <span class="builtin_type">u32</span><span class="punctuation">,</span>
+    <span class="field declaration">b</span><span class="punctuation">:</span> <span class="builtin_type">f32</span><span class="punctuation">,</span>
+<span class="punctuation">}</span>
+
 <span class="keyword">struct</span> <span class="struct declaration">HasUnsafeFn</span><span class="punctuation">;</span>
 
 <span class="keyword">impl</span> <span class="struct">HasUnsafeFn</span> <span class="punctuation">{</span>
     <span class="keyword unsafe">unsafe</span> <span class="keyword">fn</span> <span class="function declaration unsafe">unsafe_method</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">struct</span> <span class="struct declaration">TypeForStaticMut</span> <span class="punctuation">{</span>
+    <span class="field declaration">a</span><span class="punctuation">:</span> <span class="builtin_type">u8</span>
+<span class="punctuation">}</span>
+
+<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable unsafe">global_mut</span><span class="punctuation">:</span> <span class="struct">TypeForStaticMut</span> <span class="operator">=</span> <span class="struct">TypeForStaticMut</span> <span class="punctuation">{</span> <span class="field">a</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span><span class="punctuation">;</span>
+
 <span class="keyword">fn</span> <span class="function declaration">main</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="punctuation">{</span>
     <span class="keyword">let</span> <span class="variable declaration">x</span> <span class="operator">=</span> <span class="operator">&</span><span class="numeric_literal">5</span> <span class="keyword">as</span> <span class="keyword">*</span><span class="keyword">const</span> <span class="builtin_type">usize</span><span class="punctuation">;</span>
+    <span class="keyword">let</span> <span class="variable declaration">u</span> <span class="operator">=</span> <span class="union">Union</span> <span class="punctuation">{</span> <span class="field">b</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span><span class="punctuation">;</span>
     <span class="keyword unsafe">unsafe</span> <span class="punctuation">{</span>
         <span class="function unsafe">unsafe_fn</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="variable declaration">b</span> <span class="operator">=</span> <span class="variable">u</span><span class="punctuation">.</span><span class="field unsafe">b</span><span class="punctuation">;</span>
+        <span class="keyword control">match</span> <span class="variable">u</span> <span class="punctuation">{</span>
+            <span class="union">Union</span> <span class="punctuation">{</span> <span class="field unsafe">b</span><span class="punctuation">:</span> <span class="numeric_literal">0</span> <span class="punctuation">}</span> <span class="operator">=&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">,</span>
+            <span class="union">Union</span> <span class="punctuation">{</span> <span class="field unsafe">a</span> <span class="punctuation">}</span> <span class="operator">=&gt;</span> <span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">,</span>
+        <span class="punctuation">}</span>
         <span class="struct">HasUnsafeFn</span><span class="punctuation">.</span><span class="function unsafe">unsafe_method</span><span class="punctuation">(</span><span class="punctuation">)</span><span class="punctuation">;</span>
         <span class="keyword">let</span> <span class="variable declaration">y</span> <span class="operator">=</span> <span class="operator unsafe">*</span><span class="punctuation">(</span><span class="variable">x</span><span class="punctuation">)</span><span class="punctuation">;</span>
         <span class="keyword">let</span> <span class="variable declaration">z</span> <span class="operator">=</span> <span class="numeric_literal">-</span><span class="variable">x</span><span class="punctuation">;</span>
+        <span class="keyword">let</span> <span class="variable declaration">a</span> <span class="operator">=</span> <span class="static mutable unsafe">global_mut</span><span class="punctuation">.</span><span class="field">a</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/ra_ide/test_data/highlighting.html b/crates/ra_ide/test_data/highlighting.html
index 345a2f023..8e0160eee 100644
--- a/crates/ra_ide/test_data/highlighting.html
+++ b/crates/ra_ide/test_data/highlighting.html
@@ -35,7 +35,10 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
 .unresolved_reference { color: #FC5555; text-decoration: wavy underline; }
 </style>
-<pre><code><span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="attribute">]</span>
+<pre><code><span class="keyword">use</span> <span class="module">inner</span><span class="operator">::</span><span class="punctuation">{</span><span class="self_keyword">self</span> <span class="keyword">as</span> <span class="module declaration">inner_mod</span><span class="punctuation">}</span><span class="punctuation">;</span>
+<span class="keyword">mod</span> <span class="module declaration">inner</span> <span class="punctuation">{</span><span class="punctuation">}</span>
+
+<span class="attribute">#</span><span class="attribute">[</span><span class="function attribute">derive</span><span class="punctuation">(</span><span class="attribute">Clone</span><span class="punctuation">,</span><span class="attribute"> Debug</span><span class="punctuation">)</span><span class="attribute">]</span>
 <span class="keyword">struct</span> <span class="struct declaration">Foo</span> <span class="punctuation">{</span>
     <span class="keyword">pub</span> <span class="field declaration">x</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
     <span class="keyword">pub</span> <span class="field declaration">y</span><span class="punctuation">:</span> <span class="builtin_type">i32</span><span class="punctuation">,</span>
@@ -61,7 +64,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="punctuation">}</span>
 <span class="punctuation">}</span>
 
-<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable">STATIC_MUT</span><span class="punctuation">:</span> <span class="builtin_type">i32</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
+<span class="keyword">static</span> <span class="keyword">mut</span> <span class="static declaration mutable unsafe">STATIC_MUT</span><span class="punctuation">:</span> <span class="builtin_type">i32</span> <span class="operator">=</span> <span class="numeric_literal">0</span><span class="punctuation">;</span>
 
 <span class="keyword">fn</span> <span class="function declaration">foo</span><span class="punctuation">&lt;</span><span class="lifetime declaration">'a</span><span class="punctuation">,</span> <span class="type_param declaration">T</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span> <span class="operator">-&gt;</span> <span class="type_param">T</span> <span class="punctuation">{</span>
     <span class="function">foo</span><span class="operator">::</span><span class="punctuation">&lt;</span><span class="lifetime">'a</span><span class="punctuation">,</span> <span class="builtin_type">i32</span><span class="punctuation">&gt;</span><span class="punctuation">(</span><span class="punctuation">)</span>
@@ -94,7 +97,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
     <span class="punctuation">}</span>
     <span class="keyword unsafe">unsafe</span> <span class="punctuation">{</span>
         <span class="variable mutable">vec</span><span class="punctuation">.</span><span class="unresolved_reference">set_len</span><span class="punctuation">(</span><span class="numeric_literal">0</span><span class="punctuation">)</span><span class="punctuation">;</span>
-        <span class="static mutable">STATIC_MUT</span> <span class="operator">=</span> <span class="numeric_literal">1</span><span class="punctuation">;</span>
+        <span class="static mutable unsafe">STATIC_MUT</span> <span class="operator">=</span> <span class="numeric_literal">1</span><span class="punctuation">;</span>
     <span class="punctuation">}</span>
 
     <span class="keyword control">for</span> <span class="variable declaration">e</span> <span class="keyword control">in</span> <span class="variable mutable">vec</span> <span class="punctuation">{</span>
diff --git a/crates/ra_ide_db/src/change.rs b/crates/ra_ide_db/src/change.rs
index 32d9a8d1f..b13df8b85 100644
--- a/crates/ra_ide_db/src/change.rs
+++ b/crates/ra_ide_db/src/change.rs
@@ -190,11 +190,24 @@ impl RootDatabase {
                 let q: $q = Default::default();
                 let name = format!("{:?} (deps)", q);
                 acc.push((name, before - after));
+
+                let before = memory_usage().allocated;
+                $q.in_db(self).purge();
+                let after = memory_usage().allocated;
+                let q: $q = Default::default();
+                let name = format!("{:?} (purge)", q);
+                acc.push((name, before - after));
             )*}
         }
         sweep_each_query![
             // SourceDatabase
             ra_db::ParseQuery
+            ra_db::CrateGraphQuery
+
+            // SourceDatabaseExt
+            ra_db::FileTextQuery
+            ra_db::FileSourceRootQuery
+            ra_db::SourceRootQuery
             ra_db::SourceRootCratesQuery
 
             // AstDatabase
@@ -242,15 +255,24 @@ impl RootDatabase {
             hir::db::TraitImplsInCrateQuery
             hir::db::TraitImplsInDepsQuery
             hir::db::AssociatedTyDataQuery
+            hir::db::AssociatedTyDataQuery
             hir::db::TraitDatumQuery
             hir::db::StructDatumQuery
             hir::db::ImplDatumQuery
+            hir::db::FnDefDatumQuery
+            hir::db::ReturnTypeImplTraitsQuery
+            hir::db::InternCallableDefQuery
+            hir::db::InternTypeParamIdQuery
+            hir::db::InternImplTraitIdQuery
+            hir::db::InternClosureQuery
             hir::db::AssociatedTyValueQuery
             hir::db::TraitSolveQuery
-            hir::db::ReturnTypeImplTraitsQuery
 
             // SymbolsDatabase
             crate::symbol_index::FileSymbolsQuery
+            crate::symbol_index::LibrarySymbolsQuery
+            crate::symbol_index::LocalRootsQuery
+            crate::symbol_index::LibraryRootsQuery
 
             // LineIndexDatabase
             crate::LineIndexQuery
diff --git a/crates/ra_ide_db/src/defs.rs b/crates/ra_ide_db/src/defs.rs
index 66c048714..b51000b03 100644
--- a/crates/ra_ide_db/src/defs.rs
+++ b/crates/ra_ide_db/src/defs.rs
@@ -12,7 +12,7 @@ use hir::{
 use ra_prof::profile;
 use ra_syntax::{
     ast::{self, AstNode},
-    match_ast,
+    match_ast, SyntaxNode,
 };
 
 use crate::RootDatabase;
@@ -123,8 +123,27 @@ pub fn classify_name(sema: &Semantics<RootDatabase>, name: &ast::Name) -> Option
                 let use_tree = it.syntax().parent().and_then(ast::UseTree::cast)?;
                 let path = use_tree.path()?;
                 let path_segment = path.segment()?;
-                let name_ref = path_segment.name_ref()?;
-                let name_ref_class = classify_name_ref(sema, &name_ref)?;
+                let name_ref_class = path_segment
+                    .name_ref()
+                    // The rename might be from a `self` token, so fallback to the name higher
+                    // in the use tree.
+                    .or_else(||{
+                        if path_segment.self_token().is_none() {
+                            return None;
+                        }
+
+                        let use_tree = use_tree
+                            .syntax()
+                            .parent()
+                            .as_ref()
+                            // Skip over UseTreeList
+                            .and_then(SyntaxNode::parent)
+                            .and_then(ast::UseTree::cast)?;
+                        let path = use_tree.path()?;
+                        let path_segment = path.segment()?;
+                        path_segment.name_ref()
+                    })
+                    .and_then(|name_ref| classify_name_ref(sema, &name_ref))?;
 
                 Some(NameClass::Definition(name_ref_class.definition()))
             },
diff --git a/crates/ra_ssr/src/lib.rs b/crates/ra_ssr/src/lib.rs
index 73abfecb2..c780b460a 100644
--- a/crates/ra_ssr/src/lib.rs
+++ b/crates/ra_ssr/src/lib.rs
@@ -66,12 +66,7 @@ impl<'db> MatchFinder<'db> {
         restrict_ranges.retain(|range| !range.range.is_empty());
         let sema = Semantics::new(db);
         let resolution_scope = resolving::ResolutionScope::new(&sema, lookup_context);
-        MatchFinder {
-            sema: Semantics::new(db),
-            rules: Vec::new(),
-            resolution_scope,
-            restrict_ranges,
-        }
+        MatchFinder { sema, rules: Vec::new(), resolution_scope, restrict_ranges }
     }
 
     /// Constructs an instance using the start of the first file in `db` as the lookup context.
diff --git a/crates/ra_ssr/src/resolving.rs b/crates/ra_ssr/src/resolving.rs
index 6f62000f4..df60048eb 100644
--- a/crates/ra_ssr/src/resolving.rs
+++ b/crates/ra_ssr/src/resolving.rs
@@ -11,6 +11,7 @@ use test_utils::mark;
 pub(crate) struct ResolutionScope<'db> {
     scope: hir::SemanticsScope<'db>,
     hygiene: hir::Hygiene,
+    node: SyntaxNode,
 }
 
 pub(crate) struct ResolvedRule {
@@ -25,6 +26,7 @@ pub(crate) struct ResolvedPattern {
     // Paths in `node` that we've resolved.
     pub(crate) resolved_paths: FxHashMap<SyntaxNode, ResolvedPath>,
     pub(crate) ufcs_function_calls: FxHashMap<SyntaxNode, hir::Function>,
+    pub(crate) contains_self: bool,
 }
 
 pub(crate) struct ResolvedPath {
@@ -68,6 +70,7 @@ struct Resolver<'a, 'db> {
 
 impl Resolver<'_, '_> {
     fn resolve_pattern_tree(&self, pattern: SyntaxNode) -> Result<ResolvedPattern, SsrError> {
+        use ra_syntax::{SyntaxElement, T};
         let mut resolved_paths = FxHashMap::default();
         self.resolve(pattern.clone(), 0, &mut resolved_paths)?;
         let ufcs_function_calls = resolved_paths
@@ -85,11 +88,17 @@ impl Resolver<'_, '_> {
                 None
             })
             .collect();
+        let contains_self =
+            pattern.descendants_with_tokens().any(|node_or_token| match node_or_token {
+                SyntaxElement::Token(t) => t.kind() == T![self],
+                _ => false,
+            });
         Ok(ResolvedPattern {
             node: pattern,
             resolved_paths,
             placeholders_by_stand_in: self.placeholders_by_stand_in.clone(),
             ufcs_function_calls,
+            contains_self,
         })
     }
 
@@ -101,6 +110,10 @@ impl Resolver<'_, '_> {
     ) -> Result<(), SsrError> {
         use ra_syntax::ast::AstNode;
         if let Some(path) = ast::Path::cast(node.clone()) {
+            if is_self(&path) {
+                // Self cannot be resolved like other paths.
+                return Ok(());
+            }
             // Check if this is an appropriate place in the path to resolve. If the path is
             // something like `a::B::<i32>::c` then we want to resolve `a::B`. If the path contains
             // a placeholder. e.g. `a::$b::c` then we want to resolve `a`.
@@ -157,9 +170,15 @@ impl<'db> ResolutionScope<'db> {
         ResolutionScope {
             scope,
             hygiene: hir::Hygiene::new(sema.db, resolve_context.file_id.into()),
+            node,
         }
     }
 
+    /// Returns the function in which SSR was invoked, if any.
+    pub(crate) fn current_function(&self) -> Option<SyntaxNode> {
+        self.node.ancestors().find(|node| node.kind() == SyntaxKind::FN).map(|node| node.clone())
+    }
+
     fn resolve_path(&self, path: &ast::Path) -> Option<hir::PathResolution> {
         let hir_path = hir::Path::from_src(path.clone(), &self.hygiene)?;
         // First try resolving the whole path. This will work for things like
@@ -186,6 +205,10 @@ impl<'db> ResolutionScope<'db> {
     }
 }
 
+fn is_self(path: &ast::Path) -> bool {
+    path.segment().map(|segment| segment.self_token().is_some()).unwrap_or(false)
+}
+
 /// Returns a suitable node for resolving paths in the current scope. If we create a scope based on
 /// a statement node, then we can't resolve local variables that were defined in the current scope
 /// (only in parent scopes). So we find another node, ideally a child of the statement where local
diff --git a/crates/ra_ssr/src/search.rs b/crates/ra_ssr/src/search.rs
index 213dc494f..85ffa2ac2 100644
--- a/crates/ra_ssr/src/search.rs
+++ b/crates/ra_ssr/src/search.rs
@@ -33,6 +33,15 @@ impl<'db> MatchFinder<'db> {
         usage_cache: &mut UsageCache,
         matches_out: &mut Vec<Match>,
     ) {
+        if rule.pattern.contains_self {
+            // If the pattern contains `self` we restrict the scope of the search to just the
+            // current method. No other method can reference the same `self`. This makes the
+            // behavior of `self` consistent with other variables.
+            if let Some(current_function) = self.resolution_scope.current_function() {
+                self.slow_scan_node(&current_function, rule, &None, matches_out);
+            }
+            return;
+        }
         if pick_path_for_usages(&rule.pattern).is_none() {
             self.slow_scan(rule, matches_out);
             return;
diff --git a/crates/ra_ssr/src/tests.rs b/crates/ra_ssr/src/tests.rs
index 2ae03c64c..d483640df 100644
--- a/crates/ra_ssr/src/tests.rs
+++ b/crates/ra_ssr/src/tests.rs
@@ -1044,3 +1044,38 @@ fn replace_nonpath_within_selection() {
             }"#]],
     );
 }
+
+#[test]
+fn replace_self() {
+    // `foo(self)` occurs twice in the code, however only the first occurrence is the `self` that's
+    // in scope where the rule is invoked.
+    assert_ssr_transform(
+        "foo(self) ==>> bar(self)",
+        r#"
+        struct S1 {}
+        fn foo(_: &S1) {}
+        fn bar(_: &S1) {}
+        impl S1 {
+            fn f1(&self) {
+                foo(self)<|>
+            }
+            fn f2(&self) {
+                foo(self)
+            }
+        }
+        "#,
+        expect![[r#"
+            struct S1 {}
+            fn foo(_: &S1) {}
+            fn bar(_: &S1) {}
+            impl S1 {
+                fn f1(&self) {
+                    bar(self)
+                }
+                fn f2(&self) {
+                    foo(self)
+                }
+            }
+        "#]],
+    );
+}
diff --git a/crates/ra_syntax/src/ast/edit.rs b/crates/ra_syntax/src/ast/edit.rs
index 667a9294f..5ed123f91 100644
--- a/crates/ra_syntax/src/ast/edit.rs
+++ b/crates/ra_syntax/src/ast/edit.rs
@@ -621,7 +621,7 @@ fn single_node(element: impl Into<SyntaxElement>) -> RangeInclusive<SyntaxElemen
 #[test]
 fn test_increase_indent() {
     let arm_list = {
-        let arm = make::match_arm(iter::once(make::placeholder_pat().into()), make::expr_unit());
+        let arm = make::match_arm(iter::once(make::wildcard_pat().into()), make::expr_unit());
         make::match_arm_list(vec![arm.clone(), arm])
     };
     assert_eq!(
diff --git a/crates/ra_syntax/src/ast/make.rs b/crates/ra_syntax/src/ast/make.rs
index 673777015..254a37fe3 100644
--- a/crates/ra_syntax/src/ast/make.rs
+++ b/crates/ra_syntax/src/ast/make.rs
@@ -17,7 +17,7 @@ pub fn name_ref(text: &str) -> ast::NameRef {
     ast_from_text(&format!("fn f() {{ {}; }}", text))
 }
 
-pub fn type_ref(text: &str) -> ast::Type {
+pub fn ty(text: &str) -> ast::Type {
     ast_from_text(&format!("impl {} for D {{}};", text))
 }
 
@@ -30,7 +30,7 @@ pub fn path_unqualified(segment: ast::PathSegment) -> ast::Path {
 pub fn path_qualified(qual: ast::Path, segment: ast::PathSegment) -> ast::Path {
     path_from_text(&format!("{}::{}", qual, segment))
 }
-fn path_from_text(text: &str) -> ast::Path {
+pub fn path_from_text(text: &str) -> ast::Path {
     ast_from_text(text)
 }
 
@@ -60,11 +60,11 @@ pub fn use_tree_list(use_trees: impl IntoIterator<Item = ast::UseTree>) -> ast::
     ast_from_text(&format!("use {{{}}};", use_trees))
 }
 
-pub fn use_item(use_tree: ast::UseTree) -> ast::Use {
+pub fn use_(use_tree: ast::UseTree) -> ast::Use {
     ast_from_text(&format!("use {};", use_tree))
 }
 
-pub fn record_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordExprField {
+pub fn record_expr_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordExprField {
     return match expr {
         Some(expr) => from_text(&format!("{}: {}", name, expr)),
         None => from_text(&name.to_string()),
@@ -75,7 +75,7 @@ pub fn record_field(name: ast::NameRef, expr: Option<ast::Expr>) -> ast::RecordE
     }
 }
 
-pub fn record_field_def(name: ast::NameRef, ty: ast::Type) -> ast::RecordField {
+pub fn record_field(name: ast::NameRef, ty: ast::Type) -> ast::RecordField {
     ast_from_text(&format!("struct S {{ {}: {}, }}", name, ty))
 }
 
@@ -148,7 +148,7 @@ pub fn condition(expr: ast::Expr, pattern: Option<ast::Pat>) -> ast::Condition {
     }
 }
 
-pub fn bind_pat(name: ast::Name) -> ast::IdentPat {
+pub fn ident_pat(name: ast::Name) -> ast::IdentPat {
     return from_text(name.text());
 
     fn from_text(text: &str) -> ast::IdentPat {
@@ -156,7 +156,7 @@ pub fn bind_pat(name: ast::Name) -> ast::IdentPat {
     }
 }
 
-pub fn placeholder_pat() -> ast::WildcardPat {
+pub fn wildcard_pat() -> ast::WildcardPat {
     return from_text("_");
 
     fn from_text(text: &str) -> ast::WildcardPat {
@@ -288,7 +288,7 @@ pub fn visibility_pub_crate() -> ast::Visibility {
     ast_from_text("pub(crate) struct S")
 }
 
-pub fn fn_def(
+pub fn fn_(
     visibility: Option<ast::Visibility>,
     fn_name: ast::Name,
     type_params: Option<ast::GenericParamList>,
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index 37d695448..92a743fd8 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -76,7 +76,9 @@ pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabiliti
                     token_modifiers: semantic_tokens::SUPPORTED_MODIFIERS.to_vec(),
                 },
 
-                document_provider: Some(SemanticTokensDocumentProvider::Bool(true)),
+                document_provider: Some(SemanticTokensDocumentProvider::Edits {
+                    edits: Some(true),
+                }),
                 range_provider: Some(true),
                 work_done_progress_options: Default::default(),
             }
diff --git a/crates/rust-analyzer/src/document.rs b/crates/rust-analyzer/src/document.rs
index 43219e633..e882c9865 100644
--- a/crates/rust-analyzer/src/document.rs
+++ b/crates/rust-analyzer/src/document.rs
@@ -1,9 +1,9 @@
 //! In-memory document information.
 
 /// Information about a document that the Language Client
-// knows about.
-// Its lifetime is driven by the textDocument/didOpen and textDocument/didClose
-// client notifications.
+/// knows about.
+/// Its lifetime is driven by the textDocument/didOpen and textDocument/didClose
+/// client notifications.
 #[derive(Debug, Clone)]
 pub(crate) struct DocumentData {
     pub version: Option<i64>,
diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index b2d65a6d1..0e592ac1b 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -7,8 +7,8 @@ use std::{sync::Arc, time::Instant};
 
 use crossbeam_channel::{unbounded, Receiver, Sender};
 use flycheck::FlycheckHandle;
-use lsp_types::Url;
-use parking_lot::RwLock;
+use lsp_types::{SemanticTokens, Url};
+use parking_lot::{Mutex, RwLock};
 use ra_db::{CrateId, VfsPath};
 use ra_ide::{Analysis, AnalysisChange, AnalysisHost, FileId};
 use ra_project_model::{CargoWorkspace, ProcMacroClient, ProjectWorkspace, Target};
@@ -71,6 +71,7 @@ pub(crate) struct GlobalState {
     pub(crate) analysis_host: AnalysisHost,
     pub(crate) diagnostics: DiagnosticCollection,
     pub(crate) mem_docs: FxHashMap<VfsPath, DocumentData>,
+    pub(crate) semantic_tokens_cache: Arc<Mutex<FxHashMap<Url, SemanticTokens>>>,
     pub(crate) vfs: Arc<RwLock<(vfs::Vfs, FxHashMap<FileId, LineEndings>)>>,
     pub(crate) status: Status,
     pub(crate) source_root_config: SourceRootConfig,
@@ -86,6 +87,7 @@ pub(crate) struct GlobalStateSnapshot {
     pub(crate) check_fixes: CheckFixes,
     pub(crate) latest_requests: Arc<RwLock<LatestRequests>>,
     mem_docs: FxHashMap<VfsPath, DocumentData>,
+    pub semantic_tokens_cache: Arc<Mutex<FxHashMap<Url, SemanticTokens>>>,
     vfs: Arc<RwLock<(vfs::Vfs, FxHashMap<FileId, LineEndings>)>>,
     pub(crate) workspaces: Arc<Vec<ProjectWorkspace>>,
 }
@@ -120,6 +122,7 @@ impl GlobalState {
             analysis_host,
             diagnostics: Default::default(),
             mem_docs: FxHashMap::default(),
+            semantic_tokens_cache: Arc::new(Default::default()),
             vfs: Arc::new(RwLock::new((vfs::Vfs::default(), FxHashMap::default()))),
             status: Status::default(),
             source_root_config: SourceRootConfig::default(),
@@ -186,6 +189,7 @@ impl GlobalState {
             latest_requests: Arc::clone(&self.latest_requests),
             check_fixes: Arc::clone(&self.diagnostics.check_fixes),
             mem_docs: self.mem_docs.clone(),
+            semantic_tokens_cache: Arc::clone(&self.semantic_tokens_cache),
         }
     }
 
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 6994e611b..895af1dd7 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -13,9 +13,10 @@ use lsp_types::{
     CallHierarchyOutgoingCall, CallHierarchyOutgoingCallsParams, CallHierarchyPrepareParams,
     CodeActionKind, CodeLens, Command, CompletionItem, Diagnostic, DocumentFormattingParams,
     DocumentHighlight, DocumentSymbol, FoldingRange, FoldingRangeParams, HoverContents, Location,
-    Position, PrepareRenameResponse, Range, RenameParams, SemanticTokensParams,
-    SemanticTokensRangeParams, SemanticTokensRangeResult, SemanticTokensResult, SymbolInformation,
-    SymbolTag, TextDocumentIdentifier, Url, WorkspaceEdit,
+    Position, PrepareRenameResponse, Range, RenameParams, SemanticTokensEditResult,
+    SemanticTokensEditsParams, SemanticTokensParams, SemanticTokensRangeParams,
+    SemanticTokensRangeResult, SemanticTokensResult, SymbolInformation, SymbolTag,
+    TextDocumentIdentifier, Url, WorkspaceEdit,
 };
 use ra_ide::{
     FileId, FilePosition, FileRange, HoverAction, HoverGotoTypeData, NavigationTarget, Query,
@@ -709,11 +710,6 @@ pub(crate) fn handle_formatting(
         }
     };
 
-    if let Ok(path) = params.text_document.uri.to_file_path() {
-        if let Some(parent) = path.parent() {
-            rustfmt.current_dir(parent);
-        }
-    }
     let mut rustfmt = rustfmt.stdin(Stdio::piped()).stdout(Stdio::piped()).spawn()?;
 
     rustfmt.stdin.as_mut().unwrap().write_all(file.as_bytes())?;
@@ -1184,6 +1180,40 @@ pub(crate) fn handle_semantic_tokens(
 
     let highlights = snap.analysis.highlight(file_id)?;
     let semantic_tokens = to_proto::semantic_tokens(&text, &line_index, highlights);
+
+    // Unconditionally cache the tokens
+    snap.semantic_tokens_cache.lock().insert(params.text_document.uri, semantic_tokens.clone());
+
+    Ok(Some(semantic_tokens.into()))
+}
+
+pub(crate) fn handle_semantic_tokens_edits(
+    snap: GlobalStateSnapshot,
+    params: SemanticTokensEditsParams,
+) -> Result<Option<SemanticTokensEditResult>> {
+    let _p = profile("handle_semantic_tokens_edits");
+
+    let file_id = from_proto::file_id(&snap, &params.text_document.uri)?;
+    let text = snap.analysis.file_text(file_id)?;
+    let line_index = snap.analysis.file_line_index(file_id)?;
+
+    let highlights = snap.analysis.highlight(file_id)?;
+
+    let semantic_tokens = to_proto::semantic_tokens(&text, &line_index, highlights);
+
+    let mut cache = snap.semantic_tokens_cache.lock();
+    let cached_tokens = cache.entry(params.text_document.uri).or_default();
+
+    if let Some(prev_id) = &cached_tokens.result_id {
+        if *prev_id == params.previous_result_id {
+            let edits = to_proto::semantic_token_edits(&cached_tokens, &semantic_tokens);
+            *cached_tokens = semantic_tokens;
+            return Ok(Some(edits.into()));
+        }
+    }
+
+    *cached_tokens = semantic_tokens.clone();
+
     Ok(Some(semantic_tokens.into()))
 }
 
diff --git a/crates/rust-analyzer/src/lsp_utils.rs b/crates/rust-analyzer/src/lsp_utils.rs
index d4cc9dd04..0bc3ff115 100644
--- a/crates/rust-analyzer/src/lsp_utils.rs
+++ b/crates/rust-analyzer/src/lsp_utils.rs
@@ -1,5 +1,5 @@
 //! Utilities for LSP-related boilerplate code.
-use std::{borrow::Cow, error::Error, ops::Range};
+use std::{error::Error, ops::Range};
 
 use lsp_server::Notification;
 use ra_db::Canceled;
@@ -84,8 +84,8 @@ impl GlobalState {
 pub(crate) fn apply_document_changes(
     old_text: &mut String,
     content_changes: Vec<lsp_types::TextDocumentContentChangeEvent>,
-    mut line_index: Cow<'_, LineIndex>,
 ) {
+    let mut line_index = LineIndex::new(old_text);
     // The changes we got must be applied sequentially, but can cross lines so we
     // have to keep our line index updated.
     // Some clients (e.g. Code) sort the ranges in reverse. As an optimization, we
@@ -110,7 +110,7 @@ pub(crate) fn apply_document_changes(
         match change.range {
             Some(range) => {
                 if !index_valid.covers(range.end.line) {
-                    line_index = Cow::Owned(LineIndex::new(old_text));
+                    line_index = LineIndex::new(&old_text);
                 }
                 index_valid = IndexValid::UpToLineExclusive(range.start.line);
                 let range = from_proto::text_range(&line_index, range);
@@ -145,15 +145,10 @@ mod tests {
             };
         }
 
-        fn run(text: &mut String, changes: Vec<TextDocumentContentChangeEvent>) {
-            let line_index = Cow::Owned(LineIndex::new(&text));
-            super::apply_document_changes(text, changes, line_index);
-        }
-
         let mut text = String::new();
-        run(&mut text, vec![]);
+        apply_document_changes(&mut text, vec![]);
         assert_eq!(text, "");
-        run(
+        apply_document_changes(
             &mut text,
             vec![TextDocumentContentChangeEvent {
                 range: None,
@@ -162,36 +157,39 @@ mod tests {
             }],
         );
         assert_eq!(text, "the");
-        run(&mut text, c![0, 3; 0, 3 => " quick"]);
+        apply_document_changes(&mut text, c![0, 3; 0, 3 => " quick"]);
         assert_eq!(text, "the quick");
-        run(&mut text, c![0, 0; 0, 4 => "", 0, 5; 0, 5 => " foxes"]);
+        apply_document_changes(&mut text, c![0, 0; 0, 4 => "", 0, 5; 0, 5 => " foxes"]);
         assert_eq!(text, "quick foxes");
-        run(&mut text, c![0, 11; 0, 11 => "\ndream"]);
+        apply_document_changes(&mut text, c![0, 11; 0, 11 => "\ndream"]);
         assert_eq!(text, "quick foxes\ndream");
-        run(&mut text, c![1, 0; 1, 0 => "have "]);
+        apply_document_changes(&mut text, c![1, 0; 1, 0 => "have "]);
         assert_eq!(text, "quick foxes\nhave dream");
-        run(&mut text, c![0, 0; 0, 0 => "the ", 1, 4; 1, 4 => " quiet", 1, 16; 1, 16 => "s\n"]);
+        apply_document_changes(
+            &mut text,
+            c![0, 0; 0, 0 => "the ", 1, 4; 1, 4 => " quiet", 1, 16; 1, 16 => "s\n"],
+        );
         assert_eq!(text, "the quick foxes\nhave quiet dreams\n");
-        run(&mut text, c![0, 15; 0, 15 => "\n", 2, 17; 2, 17 => "\n"]);
+        apply_document_changes(&mut text, c![0, 15; 0, 15 => "\n", 2, 17; 2, 17 => "\n"]);
         assert_eq!(text, "the quick foxes\n\nhave quiet dreams\n\n");
-        run(
+        apply_document_changes(
             &mut text,
             c![1, 0; 1, 0 => "DREAM", 2, 0; 2, 0 => "they ", 3, 0; 3, 0 => "DON'T THEY?"],
         );
         assert_eq!(text, "the quick foxes\nDREAM\nthey have quiet dreams\nDON'T THEY?\n");
-        run(&mut text, c![0, 10; 1, 5 => "", 2, 0; 2, 12 => ""]);
+        apply_document_changes(&mut text, c![0, 10; 1, 5 => "", 2, 0; 2, 12 => ""]);
         assert_eq!(text, "the quick \nthey have quiet dreams\n");
 
         text = String::from("❤️");
-        run(&mut text, c![0, 0; 0, 0 => "a"]);
+        apply_document_changes(&mut text, c![0, 0; 0, 0 => "a"]);
         assert_eq!(text, "a❤️");
 
         text = String::from("a\nb");
-        run(&mut text, c![0, 1; 1, 0 => "\nțc", 0, 1; 1, 1 => "d"]);
+        apply_document_changes(&mut text, c![0, 1; 1, 0 => "\nțc", 0, 1; 1, 1 => "d"]);
         assert_eq!(text, "adcb");
 
         text = String::from("a\nb");
-        run(&mut text, c![0, 1; 1, 0 => "ț\nc", 0, 2; 0, 2 => "c"]);
+        apply_document_changes(&mut text, c![0, 1; 1, 0 => "ț\nc", 0, 2; 0, 2 => "c"]);
         assert_eq!(text, "ațc\ncb");
     }
 }
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 0ace4cb45..438e965e0 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -1,14 +1,13 @@
 //! The main loop of `rust-analyzer` responsible for dispatching LSP
 //! requests/replies and notifications back to the client.
 use std::{
-    borrow::Cow,
     env, fmt, panic,
     time::{Duration, Instant},
 };
 
 use crossbeam_channel::{select, Receiver};
 use lsp_server::{Connection, Notification, Request, Response};
-use lsp_types::{notification::Notification as _, DidChangeTextDocumentParams};
+use lsp_types::notification::Notification as _;
 use ra_db::VfsPath;
 use ra_ide::{Canceled, FileId};
 use ra_prof::profile;
@@ -48,7 +47,7 @@ pub fn main_loop(config: Config, connection: Connection) -> Result<()> {
         SetThreadPriority(thread, thread_priority_above_normal);
     }
 
-    GlobalState::new(connection.sender.clone(), config).run(connection.receiver)
+    GlobalState::new(connection.sender, config).run(connection.receiver)
 }
 
 enum Event {
@@ -387,6 +386,9 @@ impl GlobalState {
                 handlers::handle_call_hierarchy_outgoing,
             )?
             .on::<lsp_types::request::SemanticTokensRequest>(handlers::handle_semantic_tokens)?
+            .on::<lsp_types::request::SemanticTokensEditsRequest>(
+                handlers::handle_semantic_tokens_edits,
+            )?
             .on::<lsp_types::request::SemanticTokensRangeRequest>(
                 handlers::handle_semantic_tokens_range,
             )?
@@ -422,20 +424,15 @@ impl GlobalState {
             })?
             .on::<lsp_types::notification::DidChangeTextDocument>(|this, params| {
                 if let Ok(path) = from_proto::vfs_path(&params.text_document.uri) {
-                    let DidChangeTextDocumentParams { text_document, content_changes } = params;
+                    let doc = this.mem_docs.get_mut(&path).unwrap();
                     let vfs = &mut this.vfs.write().0;
-                    let world = this.snapshot();
                     let file_id = vfs.file_id(&path).unwrap();
-
-                    // let file_id = vfs.file_id(&path).unwrap();
                     let mut text = String::from_utf8(vfs.file_contents(file_id).to_vec()).unwrap();
-                    let line_index = world.analysis.file_line_index(file_id)?;
-                    apply_document_changes(&mut text, content_changes, Cow::Borrowed(&line_index));
+                    apply_document_changes(&mut text, params.content_changes);
 
                     // The version passed in DidChangeTextDocument is the version after all edits are applied
                     // so we should apply it before the vfs is notified.
-                    let doc = this.mem_docs.get_mut(&path).unwrap();
-                    doc.version = text_document.version;
+                    doc.version = params.text_document.version;
 
                     vfs.set_file_contents(path.clone(), Some(text.into_bytes()));
                 }
@@ -449,6 +446,8 @@ impl GlobalState {
                         None => log::error!("orphan DidCloseTextDocument: {}", path),
                     }
 
+                    this.semantic_tokens_cache.lock().remove(&params.text_document.uri);
+
                     if let Some(path) = path.as_path() {
                         this.loader.handle.invalidate(path.to_path_buf());
                     }
diff --git a/crates/rust-analyzer/src/semantic_tokens.rs b/crates/rust-analyzer/src/semantic_tokens.rs
index 576bd8adc..afc38fb4e 100644
--- a/crates/rust-analyzer/src/semantic_tokens.rs
+++ b/crates/rust-analyzer/src/semantic_tokens.rs
@@ -2,7 +2,10 @@
 
 use std::ops;
 
-use lsp_types::{Range, SemanticToken, SemanticTokenModifier, SemanticTokenType, SemanticTokens};
+use lsp_types::{
+    Range, SemanticToken, SemanticTokenModifier, SemanticTokenType, SemanticTokens,
+    SemanticTokensEdit,
+};
 
 macro_rules! define_semantic_token_types {
     ($(($ident:ident, $string:literal)),*$(,)?) => {
@@ -89,14 +92,18 @@ impl ops::BitOrAssign<SemanticTokenModifier> for ModifierSet {
 /// Tokens are encoded relative to each other.
 ///
 /// This is a direct port of https://github.com/microsoft/vscode-languageserver-node/blob/f425af9de46a0187adb78ec8a46b9b2ce80c5412/server/src/sematicTokens.proposed.ts#L45
-#[derive(Default)]
 pub(crate) struct SemanticTokensBuilder {
+    id: String,
     prev_line: u32,
     prev_char: u32,
     data: Vec<SemanticToken>,
 }
 
 impl SemanticTokensBuilder {
+    pub fn new(id: String) -> Self {
+        SemanticTokensBuilder { id, prev_line: 0, prev_char: 0, data: Default::default() }
+    }
+
     /// Push a new token onto the builder
     pub fn push(&mut self, range: Range, token_index: u32, modifier_bitset: u32) {
         let mut push_line = range.start.line as u32;
@@ -127,10 +134,136 @@ impl SemanticTokensBuilder {
     }
 
     pub fn build(self) -> SemanticTokens {
-        SemanticTokens { result_id: None, data: self.data }
+        SemanticTokens { result_id: Some(self.id), data: self.data }
+    }
+}
+
+pub fn diff_tokens(old: &[SemanticToken], new: &[SemanticToken]) -> Vec<SemanticTokensEdit> {
+    let offset = new.iter().zip(old.iter()).take_while(|&(n, p)| n == p).count();
+
+    let (_, old) = old.split_at(offset);
+    let (_, new) = new.split_at(offset);
+
+    let offset_from_end =
+        new.iter().rev().zip(old.iter().rev()).take_while(|&(n, p)| n == p).count();
+
+    let (old, _) = old.split_at(old.len() - offset_from_end);
+    let (new, _) = new.split_at(new.len() - offset_from_end);
+
+    if old.is_empty() && new.is_empty() {
+        vec![]
+    } else {
+        // The lsp data field is actually a byte-diff but we
+        // travel in tokens so `start` and `delete_count` are in multiples of the
+        // serialized size of `SemanticToken`.
+        vec![SemanticTokensEdit {
+            start: 5 * offset as u32,
+            delete_count: 5 * old.len() as u32,
+            data: Some(new.into()),
+        }]
     }
 }
 
 pub fn type_index(type_: SemanticTokenType) -> u32 {
     SUPPORTED_TYPES.iter().position(|it| *it == type_).unwrap() as u32
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn from(t: (u32, u32, u32, u32, u32)) -> SemanticToken {
+        SemanticToken {
+            delta_line: t.0,
+            delta_start: t.1,
+            length: t.2,
+            token_type: t.3,
+            token_modifiers_bitset: t.4,
+        }
+    }
+
+    #[test]
+    fn test_diff_insert_at_end() {
+        let before = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+        let after = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10)), from((11, 12, 13, 14, 15))];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(
+            edits[0],
+            SemanticTokensEdit {
+                start: 10,
+                delete_count: 0,
+                data: Some(vec![from((11, 12, 13, 14, 15))])
+            }
+        );
+    }
+
+    #[test]
+    fn test_diff_insert_at_beginning() {
+        let before = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+        let after = [from((11, 12, 13, 14, 15)), from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(
+            edits[0],
+            SemanticTokensEdit {
+                start: 0,
+                delete_count: 0,
+                data: Some(vec![from((11, 12, 13, 14, 15))])
+            }
+        );
+    }
+
+    #[test]
+    fn test_diff_insert_in_middle() {
+        let before = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+        let after = [
+            from((1, 2, 3, 4, 5)),
+            from((10, 20, 30, 40, 50)),
+            from((60, 70, 80, 90, 100)),
+            from((6, 7, 8, 9, 10)),
+        ];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(
+            edits[0],
+            SemanticTokensEdit {
+                start: 5,
+                delete_count: 0,
+                data: Some(vec![from((10, 20, 30, 40, 50)), from((60, 70, 80, 90, 100))])
+            }
+        );
+    }
+
+    #[test]
+    fn test_diff_remove_from_end() {
+        let before = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10)), from((11, 12, 13, 14, 15))];
+        let after = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(edits[0], SemanticTokensEdit { start: 10, delete_count: 5, data: Some(vec![]) });
+    }
+
+    #[test]
+    fn test_diff_remove_from_beginning() {
+        let before = [from((11, 12, 13, 14, 15)), from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+        let after = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(edits[0], SemanticTokensEdit { start: 0, delete_count: 5, data: Some(vec![]) });
+    }
+
+    #[test]
+    fn test_diff_remove_from_middle() {
+        let before = [
+            from((1, 2, 3, 4, 5)),
+            from((10, 20, 30, 40, 50)),
+            from((60, 70, 80, 90, 100)),
+            from((6, 7, 8, 9, 10)),
+        ];
+        let after = [from((1, 2, 3, 4, 5)), from((6, 7, 8, 9, 10))];
+
+        let edits = diff_tokens(&before, &after);
+        assert_eq!(edits[0], SemanticTokensEdit { start: 5, delete_count: 10, data: Some(vec![]) });
+    }
+}
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index fadcc5853..27460db78 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -1,5 +1,8 @@
 //! Conversion of rust-analyzer specific types to lsp_types equivalents.
-use std::path::{self, Path};
+use std::{
+    path::{self, Path},
+    sync::atomic::{AtomicU32, Ordering},
+};
 
 use itertools::Itertools;
 use ra_db::{FileId, FileRange};
@@ -303,12 +306,15 @@ pub(crate) fn inlay_int(line_index: &LineIndex, inlay_hint: InlayHint) -> lsp_ex
     }
 }
 
+static TOKEN_RESULT_COUNTER: AtomicU32 = AtomicU32::new(1);
+
 pub(crate) fn semantic_tokens(
     text: &str,
     line_index: &LineIndex,
     highlights: Vec<HighlightedRange>,
 ) -> lsp_types::SemanticTokens {
-    let mut builder = semantic_tokens::SemanticTokensBuilder::default();
+    let id = TOKEN_RESULT_COUNTER.fetch_add(1, Ordering::SeqCst).to_string();
+    let mut builder = semantic_tokens::SemanticTokensBuilder::new(id);
 
     for highlight_range in highlights {
         let (type_, mods) = semantic_token_type_and_modifiers(highlight_range.highlight);
@@ -328,6 +334,15 @@ pub(crate) fn semantic_tokens(
     builder.build()
 }
 
+pub(crate) fn semantic_token_edits(
+    previous: &lsp_types::SemanticTokens,
+    current: &lsp_types::SemanticTokens,
+) -> lsp_types::SemanticTokensEdits {
+    let result_id = current.result_id.clone();
+    let edits = semantic_tokens::diff_tokens(&previous.data, &current.data);
+    lsp_types::SemanticTokensEdits { result_id, edits }
+}
+
 fn semantic_token_type_and_modifiers(
     highlight: Highlight,
 ) -> (lsp_types::SemanticTokenType, semantic_tokens::ModifierSet) {
@@ -740,7 +755,8 @@ pub(crate) fn runnable(
 }
 
 pub(crate) fn markup_content(markup: Markup) -> lsp_types::MarkupContent {
-    lsp_types::MarkupContent { kind: lsp_types::MarkupKind::Markdown, value: markup.into() }
+    let value = crate::markdown::format_docs(markup.as_str());
+    lsp_types::MarkupContent { kind: lsp_types::MarkupKind::Markdown, value }
 }
 
 #[cfg(test)]