31 files changed, 603 insertions, 183 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 5f88ad0c4..15c6a4c11 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -471,9 +471,9 @@ dependencies = [
 
 [[package]]
 name = "inotify"
-version = "0.7.0"
+version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24e40d6fd5d64e2082e0c796495c8ef5ad667a96d03e5aaa0becfd9d47bcbfb8"
+checksum = "4816c66d2c8ae673df83366c18341538f234a26d65a9ecea5c348b453ac1d02f"
 dependencies = [
  "bitflags",
  "inotify-sys",
diff --git a/crates/ra_assists/src/handlers/introduce_named_lifetime.rs b/crates/ra_assists/src/handlers/introduce_named_lifetime.rs
index beb5b7366..28fcbc9ba 100644
--- a/crates/ra_assists/src/handlers/introduce_named_lifetime.rs
+++ b/crates/ra_assists/src/handlers/introduce_named_lifetime.rs
@@ -41,8 +41,6 @@ pub(crate) fn introduce_named_lifetime(acc: &mut Assists, ctx: &AssistContext) -
     if let Some(fn_def) = lifetime_token.ancestors().find_map(ast::FnDef::cast) {
         generate_fn_def_assist(acc, &fn_def, lifetime_token.text_range())
     } else if let Some(impl_def) = lifetime_token.ancestors().find_map(ast::ImplDef::cast) {
-        // only allow naming the last anonymous lifetime
-        lifetime_token.next_token().filter(|tok| tok.kind() == SyntaxKind::R_ANGLE)?;
         generate_impl_def_assist(acc, &impl_def, lifetime_token.text_range())
     } else {
         None
@@ -191,6 +189,23 @@ mod tests {
     }
 
     #[test]
+    fn test_impl_with_other_type_param() {
+        check_assist(
+            introduce_named_lifetime,
+            "impl<I> fmt::Display for SepByBuilder<'_<|>, I>
+        where
+            I: Iterator,
+            I::Item: fmt::Display,
+        {",
+            "impl<I, 'a> fmt::Display for SepByBuilder<'a, I>
+        where
+            I: Iterator,
+            I::Item: fmt::Display,
+        {",
+        )
+    }
+
+    #[test]
     fn test_example_case_cursor_before_tick() {
         check_assist(
             introduce_named_lifetime,
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index e7868268b..fcfa2788c 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -89,8 +89,7 @@ pub const DEFAULT_LRU_CAP: usize = 128;
 pub trait FileLoader {
     /// Text of the file.
     fn file_text(&self, file_id: FileId) -> Arc<String>;
-    fn resolve_relative_path(&self, anchor: FileId, relative_path: &RelativePath)
-        -> Option<FileId>;
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId>;
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>>;
 
     fn resolve_extern_path(
@@ -155,20 +154,21 @@ impl<T: SourceDatabaseExt> FileLoader for FileLoaderDelegate<&'_ T> {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         SourceDatabaseExt::file_text(self.0, file_id)
     }
-    fn resolve_relative_path(
-        &self,
-        anchor: FileId,
-        relative_path: &RelativePath,
-    ) -> Option<FileId> {
-        let path = {
-            let mut path = self.0.file_relative_path(anchor);
-            assert!(path.pop());
-            path.push(relative_path);
-            path.normalize()
+    /// Note that we intentionally accept a `&str` and not a `&Path` here. This
+    /// method exists to handle `#[path = "/some/path.rs"] mod foo;` and such,
+    /// so the input is guaranteed to be utf-8 string. We might introduce
+    /// `struct StrPath(str)` for clarity some day, but it's a bit messy, so we
+    /// get by with a `&str` for the time being.
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        let rel_path = {
+            let mut rel_path = self.0.file_relative_path(anchor);
+            assert!(rel_path.pop());
+            rel_path.push(path);
+            rel_path.normalize()
         };
         let source_root = self.0.file_source_root(anchor);
         let source_root = self.0.source_root(source_root);
-        source_root.file_by_relative_path(&path)
+        source_root.file_by_relative_path(&rel_path)
     }
 
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
diff --git a/crates/ra_hir_def/src/nameres/mod_resolution.rs b/crates/ra_hir_def/src/nameres/mod_resolution.rs
index 386c5cade..cede4a6fc 100644
--- a/crates/ra_hir_def/src/nameres/mod_resolution.rs
+++ b/crates/ra_hir_def/src/nameres/mod_resolution.rs
@@ -61,7 +61,7 @@ impl ModDir {
         };
 
         for candidate in candidate_files.iter() {
-            if let Some(file_id) = db.resolve_relative_path(file_id, candidate) {
+            if let Some(file_id) = db.resolve_path(file_id, candidate.as_str()) {
                 let mut root_non_dir_owner = false;
                 let mut mod_path = RelativePathBuf::new();
                 if !(candidate.ends_with("mod.rs") || attr_path.is_some()) {
diff --git a/crates/ra_hir_def/src/test_db.rs b/crates/ra_hir_def/src/test_db.rs
index eb83dee79..e7a5182f0 100644
--- a/crates/ra_hir_def/src/test_db.rs
+++ b/crates/ra_hir_def/src/test_db.rs
@@ -58,12 +58,8 @@ impl FileLoader for TestDB {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         FileLoaderDelegate(self).file_text(file_id)
     }
-    fn resolve_relative_path(
-        &self,
-        anchor: FileId,
-        relative_path: &RelativePath,
-    ) -> Option<FileId> {
-        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_path(anchor, path)
     }
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 3bce8f673..eec5fb8eb 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -8,7 +8,7 @@ use crate::{
 use crate::{quote, EagerMacroId, LazyMacroId, MacroCallId};
 use either::Either;
 use mbe::parse_to_token_tree;
-use ra_db::{FileId, RelativePath};
+use ra_db::FileId;
 use ra_parser::FragmentKind;
 
 macro_rules! register_builtin {
@@ -297,7 +297,7 @@ fn relative_file(db: &dyn AstDatabase, call_id: MacroCallId, path: &str) -> Opti
     let call_site = call_id.as_file().original_file(db);
 
     // Handle trivial case
-    if let Some(res) = db.resolve_relative_path(call_site, &RelativePath::new(&path)) {
+    if let Some(res) = db.resolve_path(call_site, path) {
         // Prevent include itself
         return if res == call_site { None } else { Some(res) };
     }
diff --git a/crates/ra_hir_expand/src/test_db.rs b/crates/ra_hir_expand/src/test_db.rs
index c1fb762de..765a2f6d1 100644
--- a/crates/ra_hir_expand/src/test_db.rs
+++ b/crates/ra_hir_expand/src/test_db.rs
@@ -41,12 +41,8 @@ impl FileLoader for TestDB {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         FileLoaderDelegate(self).file_text(file_id)
     }
-    fn resolve_relative_path(
-        &self,
-        anchor: FileId,
-        relative_path: &RelativePath,
-    ) -> Option<FileId> {
-        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_path(anchor, path)
     }
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
diff --git a/crates/ra_hir_ty/src/test_db.rs b/crates/ra_hir_ty/src/test_db.rs
index 8498d3d96..21a3bdfd1 100644
--- a/crates/ra_hir_ty/src/test_db.rs
+++ b/crates/ra_hir_ty/src/test_db.rs
@@ -72,12 +72,8 @@ impl FileLoader for TestDB {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         FileLoaderDelegate(self).file_text(file_id)
     }
-    fn resolve_relative_path(
-        &self,
-        anchor: FileId,
-        relative_path: &RelativePath,
-    ) -> Option<FileId> {
-        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_path(anchor, path)
     }
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
index 9636cd0d6..62df07459 100644
--- a/crates/ra_ide/src/hover.rs
+++ b/crates/ra_ide/src/hover.rs
@@ -13,14 +13,43 @@ use ra_ide_db::{
 use ra_syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset};
 
 use crate::{
-    display::{macro_label, rust_code_markup, rust_code_markup_with_doc, ShortLabel},
-    FilePosition, RangeInfo,
+    display::{macro_label, rust_code_markup, rust_code_markup_with_doc, ShortLabel, ToNav},
+    FilePosition, NavigationTarget, RangeInfo,
 };
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct HoverConfig {
+    pub implementations: bool,
+}
+
+impl Default for HoverConfig {
+    fn default() -> Self {
+        Self { implementations: true }
+    }
+}
+
+impl HoverConfig {
+    pub const NO_ACTIONS: Self = Self { implementations: false };
+
+    pub fn any(&self) -> bool {
+        self.implementations
+    }
+
+    pub fn none(&self) -> bool {
+        !self.any()
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum HoverAction {
+    Implementaion(FilePosition),
+}
+
 /// Contains the results when hovering over an item
 #[derive(Debug, Default)]
 pub struct HoverResult {
     results: Vec<String>,
+    actions: Vec<HoverAction>,
 }
 
 impl HoverResult {
@@ -48,10 +77,20 @@ impl HoverResult {
         &self.results
     }
 
+    pub fn actions(&self) -> &[HoverAction] {
+        &self.actions
+    }
+
+    pub fn push_action(&mut self, action: HoverAction) {
+        self.actions.push(action);
+    }
+
     /// Returns the results converted into markup
     /// for displaying in a UI
+    ///
+    /// Does not process actions!
     pub fn to_markup(&self) -> String {
-        self.results.join("\n\n---\n")
+        self.results.join("\n\n___\n")
     }
 }
 
@@ -82,6 +121,10 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         res.extend(hover_text_from_name_kind(db, name_kind));
 
         if !res.is_empty() {
+            if let Some(action) = show_implementations_action(db, name_kind) {
+                res.push_action(action);
+            }
+
             return Some(RangeInfo::new(range, res));
         }
     }
@@ -112,6 +155,26 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
     Some(RangeInfo::new(range, res))
 }
 
+fn show_implementations_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
+    fn to_action(nav_target: NavigationTarget) -> HoverAction {
+        HoverAction::Implementaion(FilePosition {
+            file_id: nav_target.file_id(),
+            offset: nav_target.range().start(),
+        })
+    }
+
+    match def {
+        Definition::ModuleDef(it) => match it {
+            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.to_nav(db))),
+            ModuleDef::Trait(it) => Some(to_action(it.to_nav(db))),
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
 fn hover_text(
     docs: Option<String>,
     desc: Option<String>,
@@ -228,6 +291,8 @@ fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
 
 #[cfg(test)]
 mod tests {
+    use super::*;
+
     use ra_db::FileLoader;
     use ra_syntax::TextRange;
 
@@ -241,7 +306,14 @@ mod tests {
         s.map(trim_markup)
     }
 
-    fn check_hover_result(fixture: &str, expected: &[&str]) -> String {
+    fn assert_impl_action(action: &HoverAction, position: u32) {
+        let offset = match action {
+            HoverAction::Implementaion(pos) => pos.offset,
+        };
+        assert_eq!(offset, position.into());
+    }
+
+    fn check_hover_result(fixture: &str, expected: &[&str]) -> (String, Vec<HoverAction>) {
         let (analysis, position) = analysis_and_position(fixture);
         let hover = analysis.hover(position).unwrap().unwrap();
         let mut results = Vec::from(hover.info.results());
@@ -256,7 +328,7 @@ mod tests {
         assert_eq!(hover.info.len(), expected.len());
 
         let content = analysis.db.file_text(position.file_id);
-        content[hover.range].to_string()
+        (content[hover.range].to_string(), hover.info.actions().to_vec())
     }
 
     fn check_hover_no_result(fixture: &str) {
@@ -746,7 +818,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id {
@@ -767,7 +839,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_expr_in_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id {
@@ -785,7 +857,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_expr_in_macro_recursive() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id_deep {
@@ -806,7 +878,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_func_in_macro_recursive() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             "
             //- /lib.rs
             macro_rules! id_deep {
@@ -830,7 +902,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_literal_string_in_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             r#"
             //- /lib.rs
             macro_rules! arr {
@@ -849,7 +921,7 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_through_assert_macro() {
-        let hover_on = check_hover_result(
+        let (hover_on, _) = check_hover_result(
             r#"
             //- /lib.rs
             #[rustc_builtin_macro]
@@ -925,13 +997,14 @@ fn func(foo: i32) { if true { <|>foo; }; }
 
     #[test]
     fn test_hover_trait_show_qualifiers() {
-        check_hover_result(
+        let (_, actions) = check_hover_result(
             "
             //- /lib.rs
             unsafe trait foo<|>() {}
             ",
             &["unsafe trait foo"],
         );
+        assert_impl_action(&actions[0], 13);
     }
 
     #[test]
@@ -1052,4 +1125,55 @@ fn func(foo: i32) { if true { <|>foo; }; }
             &["Bar\n```\n\n```rust\nfn foo(&self)\n```\n___\n\nDo the foo"],
         );
     }
+
+    #[test]
+    fn test_hover_trait_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            trait foo<|>() {}
+            ",
+            &["trait foo"],
+        );
+        assert_impl_action(&actions[0], 6);
+    }
+
+    #[test]
+    fn test_hover_struct_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            struct foo<|>() {}
+            ",
+            &["struct foo"],
+        );
+        assert_impl_action(&actions[0], 7);
+    }
+
+    #[test]
+    fn test_hover_union_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            union foo<|>() {}
+            ",
+            &["union foo"],
+        );
+        assert_impl_action(&actions[0], 6);
+    }
+
+    #[test]
+    fn test_hover_enum_has_impl_action() {
+        let (_, actions) = check_hover_result(
+            "
+            //- /lib.rs
+            enum foo<|>() {
+                A,
+                B
+            }
+            ",
+            &["enum foo"],
+        );
+        assert_impl_action(&actions[0], 5);
+    }
 }
diff --git a/crates/ra_ide/src/inlay_hints.rs b/crates/ra_ide/src/inlay_hints.rs
index 75bd3c96b..49366de98 100644
--- a/crates/ra_ide/src/inlay_hints.rs
+++ b/crates/ra_ide/src/inlay_hints.rs
@@ -149,11 +149,10 @@ fn get_param_name_hints(
         ast::Expr::MethodCallExpr(expr) => expr.arg_list()?.args(),
         _ => return None,
     };
-    let args_count = args.clone().count();
 
     let fn_signature = get_fn_signature(sema, &expr)?;
     let n_params_to_skip =
-        if fn_signature.has_self_param && fn_signature.parameter_names.len() > args_count {
+        if fn_signature.has_self_param && matches!(&expr, ast::Expr::MethodCallExpr(_)) {
             1
         } else {
             0
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 34c2d75fe..a56718d3f 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -66,7 +66,7 @@ pub use crate::{
     display::{file_structure, FunctionSignature, NavigationTarget, StructureNode},
     expand_macro::ExpandedMacro,
     folding_ranges::{Fold, FoldKind},
-    hover::HoverResult,
+    hover::{HoverAction, HoverConfig, HoverResult},
     inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
     references::{Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult},
     runnables::{Runnable, RunnableKind, TestId},
diff --git a/crates/ra_ide_db/src/defs.rs b/crates/ra_ide_db/src/defs.rs
index 8b06cbfc5..1db60b87f 100644
--- a/crates/ra_ide_db/src/defs.rs
+++ b/crates/ra_ide_db/src/defs.rs
@@ -18,7 +18,7 @@ use ra_syntax::{
 use crate::RootDatabase;
 
 // FIXME: a more precise name would probably be `Symbol`?
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 pub enum Definition {
     Macro(MacroDef),
     Field(Field),
diff --git a/crates/ra_ide_db/src/lib.rs b/crates/ra_ide_db/src/lib.rs
index 1b74e6558..93d5891a0 100644
--- a/crates/ra_ide_db/src/lib.rs
+++ b/crates/ra_ide_db/src/lib.rs
@@ -57,12 +57,8 @@ impl FileLoader for RootDatabase {
     fn file_text(&self, file_id: FileId) -> Arc<String> {
         FileLoaderDelegate(self).file_text(file_id)
     }
-    fn resolve_relative_path(
-        &self,
-        anchor: FileId,
-        relative_path: &RelativePath,
-    ) -> Option<FileId> {
-        FileLoaderDelegate(self).resolve_relative_path(anchor, relative_path)
+    fn resolve_path(&self, anchor: FileId, path: &str) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_path(anchor, path)
     }
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
diff --git a/crates/ra_parser/src/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index 67a924de5..9c14b954a 100644
--- a/crates/ra_parser/src/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
@@ -118,7 +118,17 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker, flavor: ItemFlavor) -> Resul
         && p.at_contextual_kw("default")
         && (match p.nth(1) {
             T![impl] => true,
-            T![fn] | T![type] => {
+            T![unsafe] => {
+                // test default_unsafe_impl
+                // default unsafe impl Foo {}
+                if p.nth(2) == T![impl] {
+                    p.bump_remap(T![default]);
+                    p.bump(T![unsafe]);
+                    has_mods = true;
+                }
+                false
+            }
+            T![fn] | T![type] | T![const] => {
                 if let ItemFlavor::Mod = flavor {
                     true
                 } else {
@@ -198,6 +208,9 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker, flavor: ItemFlavor) -> Resul
         //     default type T = Bar;
         //     default fn foo() {}
         // }
+        T![const] => {
+            consts::const_def(p, m);
+        }
 
         // test unsafe_default_impl
         // unsafe default impl Foo {}
diff --git a/crates/ra_syntax/test_data/parser/err/0043_default_const.rast b/crates/ra_syntax/test_data/parser/err/0043_default_const.rast
new file mode 100644
index 000000000..8eb583ef8
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0043_default_const.rast
@@ -0,0 +1,40 @@
+[email protected]
+  [email protected]
+    [email protected] "trait"
+    [email protected] " "
+    [email protected]
+      [email protected] "T"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n  "
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected] "default"
+      [email protected] " "
+      [email protected]
+        [email protected] "const"
+        [email protected] " "
+        [email protected]
+          [email protected] "f"
+        [email protected] ":"
+        [email protected] " "
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "u8"
+        [email protected] " "
+        [email protected] "="
+        [email protected] " "
+        [email protected]
+          [email protected] "0"
+        [email protected] ";"
+      [email protected] "\n"
+      [email protected] "}"
+  [email protected] "\n"
+error 19..19: expected BANG
+error 19..19: expected `{`, `[`, `(`
+error 19..19: expected SEMICOLON
diff --git a/crates/ra_syntax/test_data/parser/err/0043_default_const.rs b/crates/ra_syntax/test_data/parser/err/0043_default_const.rs
new file mode 100644
index 000000000..80f15474a
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/err/0043_default_const.rs
@@ -0,0 +1,3 @@
+trait T {
+  default const f: u8 = 0;
+}
diff --git a/crates/ra_syntax/test_data/parser/inline/err/0010_wrong_order_fns.rast b/crates/ra_syntax/test_data/parser/inline/err/0010_wrong_order_fns.rast
index 9be441110..53f7ebaf9 100644
--- a/crates/ra_syntax/test_data/parser/inline/err/0010_wrong_order_fns.rast
+++ b/crates/ra_syntax/test_data/parser/inline/err/0010_wrong_order_fns.rast
@@ -17,23 +17,29 @@ [email protected]
       [email protected] "{"
       [email protected] "}"
   [email protected] "\n"
-  ERROR@25..31
+  CONST_DEF@25..46
     [email protected] "unsafe"
-  [email protected] " "
-  [email protected]
+    [email protected] " "
     [email protected] "const"
     [email protected] " "
-    [email protected] "fn"
+    [email protected]
+      [email protected] "fn"
     [email protected] " "
-    [email protected]
-      [email protected] "bar"
-    [email protected]
-      [email protected] "("
-      [email protected] ")"
-    [email protected] " "
-    [email protected]
-      [email protected] "{"
-      [email protected] "}"
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "bar"
+          [email protected]
+            [email protected] "("
+            [email protected] ")"
+  [email protected] " "
+  [email protected]
+    [email protected] "{"
+    [email protected] "}"
   [email protected] "\n"
 error 6..6: expected existential, fn, trait or impl
-error 31..31: expected existential, fn, trait or impl
+error 38..38: expected a name
+error 40..40: expected COLON
+error 46..46: expected SEMICOLON
+error 47..47: expected an item
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rast b/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rast
new file mode 100644
index 000000000..a9eda5668
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rast
@@ -0,0 +1,18 @@
+[email protected]
+  [email protected]
+    [email protected] "default"
+    [email protected] " "
+    [email protected] "unsafe"
+    [email protected] " "
+    [email protected] "impl"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "Foo"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rs b/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rs
new file mode 100644
index 000000000..ba0998ff4
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/inline/ok/0163_default_unsafe_impl.rs
@@ -0,0 +1 @@
+default unsafe impl Foo {}
diff --git a/crates/ra_syntax/test_data/parser/ok/0066_default_const.rast b/crates/ra_syntax/test_data/parser/ok/0066_default_const.rast
new file mode 100644
index 000000000..dab0247ee
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0066_default_const.rast
@@ -0,0 +1,44 @@
+[email protected]
+  [email protected]
+    [email protected] "impl"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "T"
+    [email protected] " "
+    [email protected] "for"
+    [email protected] " "
+    [email protected]
+      [email protected]
+        [email protected]
+          [email protected]
+            [email protected] "Foo"
+    [email protected] " "
+    [email protected]
+      [email protected] "{"
+      [email protected] "\n  "
+      [email protected]
+        [email protected] "default"
+        [email protected] " "
+        [email protected] "const"
+        [email protected] " "
+        [email protected]
+          [email protected] "f"
+        [email protected] ":"
+        [email protected] " "
+        [email protected]
+          [email protected]
+            [email protected]
+              [email protected]
+                [email protected] "u8"
+        [email protected] " "
+        [email protected] "="
+        [email protected] " "
+        [email protected]
+          [email protected] "0"
+        [email protected] ";"
+      [email protected] "\n"
+      [email protected] "}"
+  [email protected] "\n"
diff --git a/crates/ra_syntax/test_data/parser/ok/0066_default_const.rs b/crates/ra_syntax/test_data/parser/ok/0066_default_const.rs
new file mode 100644
index 000000000..dfb3b92dc
--- /dev/null
+++ b/crates/ra_syntax/test_data/parser/ok/0066_default_const.rs
@@ -0,0 +1,3 @@
+impl T for Foo {
+  default const f: u8 = 0;
+}
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 23168c3ae..8d6efdbe8 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -11,7 +11,7 @@ use std::{ffi::OsString, path::PathBuf};
 
 use lsp_types::ClientCapabilities;
 use ra_flycheck::FlycheckConfig;
-use ra_ide::{AssistConfig, CompletionConfig, InlayHintsConfig};
+use ra_ide::{AssistConfig, CompletionConfig, HoverConfig, InlayHintsConfig};
 use ra_project_model::{CargoConfig, JsonProject, ProjectManifest};
 use serde::Deserialize;
 
@@ -34,6 +34,7 @@ pub struct Config {
     pub assist: AssistConfig,
     pub call_info_full: bool,
     pub lens: LensConfig,
+    pub hover: HoverConfig,
 
     pub with_sysroot: bool,
     pub linked_projects: Vec<LinkedProject>,
@@ -124,6 +125,7 @@ pub struct ClientCapsConfig {
     pub work_done_progress: bool,
     pub code_action_group: bool,
     pub resolve_code_action: bool,
+    pub hover_actions: bool,
 }
 
 impl Default for Config {
@@ -162,6 +164,7 @@ impl Default for Config {
             assist: AssistConfig::default(),
             call_info_full: true,
             lens: LensConfig::default(),
+            hover: HoverConfig::default(),
             linked_projects: Vec::new(),
         }
     }
@@ -278,6 +281,14 @@ impl Config {
             }
         }
 
+        let mut use_hover_actions = false;
+        set(value, "/hoverActions/enable", &mut use_hover_actions);
+        if use_hover_actions {
+            set(value, "/hoverActions/implementations", &mut self.hover.implementations);
+        } else {
+            self.hover = HoverConfig::NO_ACTIONS;
+        }
+
         log::info!("Config::update() = {:#?}", self);
 
         fn get<'a, T: Deserialize<'a>>(value: &'a serde_json::Value, pointer: &str) -> Option<T> {
@@ -331,17 +342,15 @@ impl Config {
 
         self.assist.allow_snippets(false);
         if let Some(experimental) = &caps.experimental {
-            let snippet_text_edit =
-                experimental.get("snippetTextEdit").and_then(|it| it.as_bool()) == Some(true);
-            self.assist.allow_snippets(snippet_text_edit);
+            let get_bool =
+                |index: &str| experimental.get(index).and_then(|it| it.as_bool()) == Some(true);
 
-            let code_action_group =
-                experimental.get("codeActionGroup").and_then(|it| it.as_bool()) == Some(true);
-            self.client_caps.code_action_group = code_action_group;
+            let snippet_text_edit = get_bool("snippetTextEdit");
+            self.assist.allow_snippets(snippet_text_edit);
 
-            let resolve_code_action =
-                experimental.get("resolveCodeAction").and_then(|it| it.as_bool()) == Some(true);
-            self.client_caps.resolve_code_action = resolve_code_action;
+            self.client_caps.code_action_group = get_bool("codeActionGroup");
+            self.client_caps.resolve_code_action = get_bool("resolveCodeAction");
+            self.client_caps.hover_actions = get_bool("hoverActions");
         }
     }
 }
diff --git a/crates/rust-analyzer/src/lsp_ext.rs b/crates/rust-analyzer/src/lsp_ext.rs
index 3b957534d..1371f6cb4 100644
--- a/crates/rust-analyzer/src/lsp_ext.rs
+++ b/crates/rust-analyzer/src/lsp_ext.rs
@@ -260,3 +260,35 @@ pub struct SnippetTextEdit {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub insert_text_format: Option<lsp_types::InsertTextFormat>,
 }
+
+pub enum HoverRequest {}
+
+impl Request for HoverRequest {
+    type Params = lsp_types::HoverParams;
+    type Result = Option<Hover>;
+    const METHOD: &'static str = "textDocument/hover";
+}
+
+#[derive(Debug, PartialEq, Clone, Deserialize, Serialize)]
+pub struct Hover {
+    #[serde(flatten)]
+    pub hover: lsp_types::Hover,
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    pub actions: Vec<CommandLinkGroup>,
+}
+
+#[derive(Debug, PartialEq, Clone, Default, Deserialize, Serialize)]
+pub struct CommandLinkGroup {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    pub commands: Vec<CommandLink>,
+}
+
+// LSP v3.15 Command does not have a `tooltip` field, vscode supports one.
+#[derive(Debug, PartialEq, Clone, Default, Deserialize, Serialize)]
+pub struct CommandLink {
+    #[serde(flatten)]
+    pub command: lsp_types::Command,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tooltip: Option<String>,
+}
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index e60337b8e..752dbf145 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -510,6 +510,7 @@ fn on_request(
         .on::<lsp_ext::InlayHints>(handlers::handle_inlay_hints)?
         .on::<lsp_ext::CodeActionRequest>(handlers::handle_code_action)?
         .on::<lsp_ext::ResolveCodeActionRequest>(handlers::handle_resolve_code_action)?
+        .on::<lsp_ext::HoverRequest>(handlers::handle_hover)?
         .on::<lsp_types::request::OnTypeFormatting>(handlers::handle_on_type_formatting)?
         .on::<lsp_types::request::DocumentSymbolRequest>(handlers::handle_document_symbol)?
         .on::<lsp_types::request::WorkspaceSymbol>(handlers::handle_workspace_symbol)?
@@ -521,7 +522,6 @@ fn on_request(
         .on::<lsp_types::request::CodeLensResolve>(handlers::handle_code_lens_resolve)?
         .on::<lsp_types::request::FoldingRangeRequest>(handlers::handle_folding_range)?
         .on::<lsp_types::request::SignatureHelpRequest>(handlers::handle_signature_help)?
-        .on::<lsp_types::request::HoverRequest>(handlers::handle_hover)?
         .on::<lsp_types::request::PrepareRenameRequest>(handlers::handle_prepare_rename)?
         .on::<lsp_types::request::Rename>(handlers::handle_rename)?
         .on::<lsp_types::request::References>(handlers::handle_references)?
diff --git a/crates/rust-analyzer/src/main_loop/handlers.rs b/crates/rust-analyzer/src/main_loop/handlers.rs
index 6acf80c58..3ff779702 100644
--- a/crates/rust-analyzer/src/main_loop/handlers.rs
+++ b/crates/rust-analyzer/src/main_loop/handlers.rs
@@ -12,13 +12,14 @@ use lsp_types::{
     CallHierarchyIncomingCall, CallHierarchyIncomingCallsParams, CallHierarchyItem,
     CallHierarchyOutgoingCall, CallHierarchyOutgoingCallsParams, CallHierarchyPrepareParams,
     CodeLens, Command, CompletionItem, Diagnostic, DocumentFormattingParams, DocumentHighlight,
-    DocumentSymbol, FoldingRange, FoldingRangeParams, Hover, HoverContents, Location,
-    MarkupContent, MarkupKind, Position, PrepareRenameResponse, Range, RenameParams,
-    SemanticTokensParams, SemanticTokensRangeParams, SemanticTokensRangeResult,
-    SemanticTokensResult, SymbolInformation, TextDocumentIdentifier, Url, WorkspaceEdit,
+    DocumentSymbol, FoldingRange, FoldingRangeParams, HoverContents, Location, MarkupContent,
+    MarkupKind, Position, PrepareRenameResponse, Range, RenameParams, SemanticTokensParams,
+    SemanticTokensRangeParams, SemanticTokensRangeResult, SemanticTokensResult, SymbolInformation,
+    TextDocumentIdentifier, Url, WorkspaceEdit,
 };
 use ra_ide::{
-    FileId, FilePosition, FileRange, Query, RangeInfo, RunnableKind, SearchScope, TextEdit,
+    FileId, FilePosition, FileRange, HoverAction, Query, RangeInfo, RunnableKind, SearchScope,
+    TextEdit,
 };
 use ra_prof::profile;
 use ra_project_model::TargetKind;
@@ -537,7 +538,7 @@ pub fn handle_signature_help(
 pub fn handle_hover(
     snap: GlobalStateSnapshot,
     params: lsp_types::HoverParams,
-) -> Result<Option<Hover>> {
+) -> Result<Option<lsp_ext::Hover>> {
     let _p = profile("handle_hover");
     let position = from_proto::file_position(&snap, params.text_document_position_params)?;
     let info = match snap.analysis().hover(position)? {
@@ -546,14 +547,18 @@ pub fn handle_hover(
     };
     let line_index = snap.analysis.file_line_index(position.file_id)?;
     let range = to_proto::range(&line_index, info.range);
-    let res = Hover {
-        contents: HoverContents::Markup(MarkupContent {
-            kind: MarkupKind::Markdown,
-            value: crate::markdown::format_docs(&info.info.to_markup()),
-        }),
-        range: Some(range),
+    let hover = lsp_ext::Hover {
+        hover: lsp_types::Hover {
+            contents: HoverContents::Markup(MarkupContent {
+                kind: MarkupKind::Markdown,
+                value: crate::markdown::format_docs(&info.info.to_markup()),
+            }),
+            range: Some(range),
+        },
+        actions: prepare_hover_actions(&snap, info.info.actions()),
     };
-    Ok(Some(res))
+
+    Ok(Some(hover))
 }
 
 pub fn handle_prepare_rename(
@@ -924,24 +929,13 @@ pub fn handle_code_lens_resolve(
                     _ => vec![],
                 };
 
-            let title = if locations.len() == 1 {
-                "1 implementation".into()
-            } else {
-                format!("{} implementations", locations.len())
-            };
-
-            // We cannot use the 'editor.action.showReferences' command directly
-            // because that command requires vscode types which we convert in the handler
-            // on the client side.
-            let cmd = Command {
+            let title = implementation_title(locations.len());
+            let cmd = show_references_command(
                 title,
-                command: "rust-analyzer.showReferences".into(),
-                arguments: Some(vec![
-                    to_value(&lens_params.text_document_position_params.text_document.uri).unwrap(),
-                    to_value(code_lens.range.start).unwrap(),
-                    to_value(locations).unwrap(),
-                ]),
-            };
+                &lens_params.text_document_position_params.text_document.uri,
+                code_lens.range.start,
+                locations,
+            );
             Ok(CodeLens { range: code_lens.range, command: Some(cmd), data: None })
         }
         None => Ok(CodeLens {
@@ -1145,3 +1139,78 @@ pub fn handle_semantic_tokens_range(
     let semantic_tokens = to_proto::semantic_tokens(&text, &line_index, highlights);
     Ok(Some(semantic_tokens.into()))
 }
+
+fn implementation_title(count: usize) -> String {
+    if count == 1 {
+        "1 implementation".into()
+    } else {
+        format!("{} implementations", count)
+    }
+}
+
+fn show_references_command(
+    title: String,
+    uri: &lsp_types::Url,
+    position: lsp_types::Position,
+    locations: Vec<lsp_types::Location>,
+) -> Command {
+    // We cannot use the 'editor.action.showReferences' command directly
+    // because that command requires vscode types which we convert in the handler
+    // on the client side.
+
+    Command {
+        title,
+        command: "rust-analyzer.showReferences".into(),
+        arguments: Some(vec![
+            to_value(uri).unwrap(),
+            to_value(position).unwrap(),
+            to_value(locations).unwrap(),
+        ]),
+    }
+}
+
+fn to_command_link(command: Command, tooltip: String) -> lsp_ext::CommandLink {
+    lsp_ext::CommandLink { tooltip: Some(tooltip), command }
+}
+
+fn show_impl_command_link(
+    snap: &GlobalStateSnapshot,
+    position: &FilePosition,
+) -> Option<lsp_ext::CommandLinkGroup> {
+    if snap.config.hover.implementations {
+        if let Some(nav_data) = snap.analysis().goto_implementation(*position).unwrap_or(None) {
+            let uri = to_proto::url(snap, position.file_id).ok()?;
+            let line_index = snap.analysis().file_line_index(position.file_id).ok()?;
+            let position = to_proto::position(&line_index, position.offset);
+            let locations: Vec<_> = nav_data
+                .info
+                .iter()
+                .filter_map(|it| to_proto::location(snap, it.file_range()).ok())
+                .collect();
+            let title = implementation_title(locations.len());
+            let command = show_references_command(title, &uri, position, locations);
+
+            return Some(lsp_ext::CommandLinkGroup {
+                commands: vec![to_command_link(command, "Go to implementations".into())],
+                ..Default::default()
+            });
+        }
+    }
+    None
+}
+
+fn prepare_hover_actions(
+    snap: &GlobalStateSnapshot,
+    actions: &[HoverAction],
+) -> Vec<lsp_ext::CommandLinkGroup> {
+    if snap.config.hover.none() || !snap.config.client_caps.hover_actions {
+        return Vec::new();
+    }
+
+    actions
+        .iter()
+        .filter_map(|it| match it {
+            HoverAction::Implementaion(position) => show_impl_command_link(snap, position),
+        })
+        .collect()
+}
diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/heavy_tests/main.rs
index ad3476310..0e2a83c6a 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/heavy_tests/main.rs
@@ -4,9 +4,7 @@ use std::{collections::HashMap, path::PathBuf, time::Instant};
 
 use lsp_types::{
     notification::DidOpenTextDocument,
-    request::{
-        CodeActionRequest, Completion, Formatting, GotoDefinition, GotoTypeDefinition, HoverRequest,
-    },
+    request::{CodeActionRequest, Completion, Formatting, GotoTypeDefinition, HoverRequest},
     CodeActionContext, CodeActionParams, CompletionParams, DidOpenTextDocumentParams,
     DocumentFormattingParams, FormattingOptions, GotoDefinitionParams, HoverParams,
     PartialResultParams, Position, Range, TextDocumentItem, TextDocumentPositionParams,
@@ -507,6 +505,10 @@ fn main() {
     println!("cargo:rerun-if-changed=build.rs");
 }
 //- src/main.rs
+#[rustc_builtin_macro] macro_rules! include {}
+#[rustc_builtin_macro] macro_rules! concat {}
+#[rustc_builtin_macro] macro_rules! env {}
+
 include!(concat!(env!("OUT_DIR"), "/hello.rs"));
 
 #[cfg(atom_cfg)]
@@ -521,10 +523,8 @@ struct B;
 fn main() {
     let va = A;
     let vb = B;
-    message();
+    let should_be_str = message();
 }
-
-fn main() { message(); }
 "###,
     )
     .with_config(|config| {
@@ -532,54 +532,35 @@ fn main() { message(); }
     })
     .server();
     server.wait_until_workspace_is_loaded();
-    let res = server.send_request::<GotoDefinition>(GotoDefinitionParams {
+    let res = server.send_request::<HoverRequest>(HoverParams {
         text_document_position_params: TextDocumentPositionParams::new(
             server.doc_id("src/main.rs"),
-            Position::new(14, 8),
+            Position::new(18, 10),
         ),
         work_done_progress_params: Default::default(),
-        partial_result_params: Default::default(),
     });
-    assert!(format!("{}", res).contains("hello.rs"));
+    assert!(res.to_string().contains("&str"));
     server.request::<GotoTypeDefinition>(
         GotoDefinitionParams {
             text_document_position_params: TextDocumentPositionParams::new(
                 server.doc_id("src/main.rs"),
-                Position::new(12, 9),
+                Position::new(16, 9),
             ),
             work_done_progress_params: Default::default(),
             partial_result_params: Default::default(),
         },
         json!([{
             "originSelectionRange": {
-                "end": {
-                    "character": 10,
-                    "line": 12
-                },
-                "start": {
-                    "character": 8,
-                    "line": 12
-                }
+                "end": { "character": 10, "line": 16 },
+                "start": { "character": 8, "line": 16 }
             },
             "targetRange": {
-                "end": {
-                    "character": 9,
-                    "line": 3
-                },
-                "start": {
-                    "character": 0,
-                    "line": 2
-                }
+                "end": { "character": 9, "line": 7 },
+                "start": { "character": 0, "line": 6 }
             },
             "targetSelectionRange": {
-                "end": {
-                    "character": 8,
-                    "line": 3
-                },
-                "start": {
-                    "character": 7,
-                    "line": 3
-                }
+                "end": { "character": 8, "line": 7 },
+                "start": { "character": 7, "line": 7 }
             },
             "targetUri": "file:///[..]src/main.rs"
         }]),
@@ -588,41 +569,23 @@ fn main() { message(); }
         GotoDefinitionParams {
             text_document_position_params: TextDocumentPositionParams::new(
                 server.doc_id("src/main.rs"),
-                Position::new(13, 9),
+                Position::new(17, 9),
             ),
             work_done_progress_params: Default::default(),
             partial_result_params: Default::default(),
         },
         json!([{
             "originSelectionRange": {
-                "end": {
-                    "character": 10,
-                    "line": 13
-                },
-                "start": {
-                    "character": 8,
-                    "line":13
-                }
+                "end": { "character": 10, "line": 17 },
+                "start": { "character": 8, "line": 17 }
             },
             "targetRange": {
-                "end": {
-                    "character": 9,
-                    "line": 7
-                },
-                "start": {
-                    "character": 0,
-                    "line":6
-                }
+                "end": { "character": 9, "line": 11 },
+                "start": { "character": 0, "line":10 }
             },
             "targetSelectionRange": {
-                "end": {
-                    "character": 8,
-                    "line": 7
-                },
-                "start": {
-                    "character": 7,
-                    "line": 7
-                }
+                "end": { "character": 8, "line": 11 },
+                "start": { "character": 7, "line": 11 }
             },
             "targetUri": "file:///[..]src/main.rs"
         }]),
diff --git a/docs/dev/lsp-extensions.md b/docs/dev/lsp-extensions.md
index 7f7940d0b..a0847dad3 100644
--- a/docs/dev/lsp-extensions.md
+++ b/docs/dev/lsp-extensions.md
@@ -467,3 +467,41 @@ interface InlayHint {
     label: string,
 }
 ```
+
+## Hover Actions
+
+**Client Capability:** `{ "hoverActions": boolean }`
+
+If this capability is set, `Hover` request returned from the server might contain an additional field, `actions`:
+
+```typescript
+interface Hover {
+    ...
+    actions?: CommandLinkGroup[];
+}
+
+interface CommandLink extends Command {
+    /**
+     * A tooltip for the command, when represented in the UI.
+     */
+    tooltip?: string;
+}
+
+interface CommandLinkGroup {
+    title?: string;
+    commands: CommandLink[];
+}
+```
+
+Such actions on the client side are appended to a hover bottom as command links:
+```
+  +-----------------------------+
+  | Hover content               |
+  |                             |
+  +-----------------------------+
+  | _Action1_ | _Action2_       |  <- first group, no TITLE
+  +-----------------------------+
+  | TITLE _Action1_ | _Action2_ |  <- second group
+  +-----------------------------+
+  ...
+```
\ No newline at end of file
diff --git a/editors/code/package.json b/editors/code/package.json
index 30ab7ba4a..b9c57db3b 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -462,17 +462,27 @@
                     "default": true
                 },
                 "rust-analyzer.lens.run": {
-                    "markdownDescription": "Whether to show Run lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
+                    "markdownDescription": "Whether to show `Run` lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
                     "type": "boolean",
                     "default": true
                 },
                 "rust-analyzer.lens.debug": {
-                    "markdownDescription": "Whether to show Debug lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
+                    "markdownDescription": "Whether to show `Debug` lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
                     "type": "boolean",
                     "default": true
                 },
                 "rust-analyzer.lens.implementations": {
-                    "markdownDescription": "Whether to show Implementations lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
+                    "markdownDescription": "Whether to show `Implementations` lens. Only applies when `#rust-analyzer.lens.enable#` is set.",
+                    "type": "boolean",
+                    "default": true
+                },
+                "rust-analyzer.hoverActions.enable": {
+                    "description": "Whether to show HoverActions in Rust files.",
+                    "type": "boolean",
+                    "default": true
+                },
+                "rust-analyzer.hoverActions.implementations": {
+                    "markdownDescription": "Whether to show `Implementations` action. Only applies when `#rust-analyzer.hoverActions.enable#` is set.",
                     "type": "boolean",
                     "default": true
                 },
diff --git a/editors/code/src/client.ts b/editors/code/src/client.ts
index 40ad1e3cd..65ad573d8 100644
--- a/editors/code/src/client.ts
+++ b/editors/code/src/client.ts
@@ -7,6 +7,20 @@ import { CallHierarchyFeature } from 'vscode-languageclient/lib/callHierarchy.pr
 import { SemanticTokensFeature, DocumentSemanticsTokensSignature } from 'vscode-languageclient/lib/semanticTokens.proposed';
 import { assert } from './util';
 
+function renderCommand(cmd: ra.CommandLink) {
+    return `[${cmd.title}](command:${cmd.command}?${encodeURIComponent(JSON.stringify(cmd.arguments))} '${cmd.tooltip!}')`;
+}
+
+function renderHoverActions(actions: ra.CommandLinkGroup[]): vscode.MarkdownString {
+    const text = actions.map(group =>
+        (group.title ? (group.title + " ") : "") + group.commands.map(renderCommand).join(' | ')
+    ).join('___');
+
+    const result = new vscode.MarkdownString(text);
+    result.isTrusted = true;
+    return result;
+}
+
 export function createClient(serverPath: string, cwd: string): lc.LanguageClient {
     // '.' Is the fallback if no folder is open
     // TODO?: Workspace folders support Uri's (eg: file://test.txt).
@@ -35,6 +49,23 @@ export function createClient(serverPath: string, cwd: string): lc.LanguageClient
                 if (res === undefined) throw new Error('busy');
                 return res;
             },
+            async provideHover(document: vscode.TextDocument, position: vscode.Position, token: vscode.CancellationToken, _next: lc.ProvideHoverSignature) {
+                return client.sendRequest(lc.HoverRequest.type, client.code2ProtocolConverter.asTextDocumentPositionParams(document, position), token).then(
+                    (result) => {
+                        const hover = client.protocol2CodeConverter.asHover(result);
+                        if (hover) {
+                            const actions = (<any>result).actions;
+                            if (actions) {
+                                hover.contents.push(renderHoverActions(actions));
+                            }
+                        }
+                        return hover;
+                    },
+                    (error) => {
+                        client.logFailedRequest(lc.HoverRequest.type, error);
+                        return Promise.resolve(null);
+                    });
+            },
             // Using custom handling of CodeActions where each code action is resloved lazily
             // That's why we are not waiting for any command or edits
             async provideCodeActions(document: vscode.TextDocument, range: vscode.Range, context: vscode.CodeActionContext, token: vscode.CancellationToken, _next: lc.ProvideCodeActionsSignature) {
@@ -129,6 +160,7 @@ class ExperimentalFeatures implements lc.StaticFeature {
         caps.snippetTextEdit = true;
         caps.codeActionGroup = true;
         caps.resolveCodeAction = true;
+        caps.hoverActions = true;
         capabilities.experimental = caps;
     }
     initialize(_capabilities: lc.ServerCapabilities<any>, _documentSelector: lc.DocumentSelector | undefined): void {
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index e8abf8284..d8f0037d4 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -16,10 +16,8 @@ export class Config {
         "files",
         "highlighting",
         "updates.channel",
-        "lens.enable",
-        "lens.run",
-        "lens.debug",
-        "lens.implementations",
+        "lens", // works as lens.*
+        "hoverActions", // works as hoverActions.*
     ]
         .map(opt => `${this.rootSection}.${opt}`);
 
@@ -132,4 +130,11 @@ export class Config {
             implementations: this.get<boolean>("lens.implementations"),
         };
     }
+
+    get hoverActions() {
+        return {
+            enable: this.get<boolean>("hoverActions.enable"),
+            implementations: this.get<boolean>("hoverActions.implementations"),
+        };
+    }
 }
diff --git a/editors/code/src/lsp_ext.ts b/editors/code/src/lsp_ext.ts
index 9793b926c..e16ea799c 100644
--- a/editors/code/src/lsp_ext.ts
+++ b/editors/code/src/lsp_ext.ts
@@ -90,3 +90,15 @@ export interface SsrParams {
     parseOnly: boolean;
 }
 export const ssr = new lc.RequestType<SsrParams, lc.WorkspaceEdit, void>('experimental/ssr');
+
+export interface CommandLink extends lc.Command {
+    /**
+     * A tooltip for the command, when represented in the UI.
+     */
+    tooltip?: string;
+}
+
+export interface CommandLinkGroup {
+    title?: string;
+    commands: CommandLink[];
+}