Merge #7154

7154: Show goto type actions for Const and TypeParams r=matklad a=Veykril

Shows goto type actions for type parameters:
![Code_6hn3rowu9M](https://user-images.githubusercontent.com/3757771/103547890-42aaeb00-4ea5-11eb-8ac7-f166869af5f8.png)

Shows goto type actions for const parameters:
![Code_8UFCcbZL3z](https://user-images.githubusercontent.com/3757771/103547891-43438180-4ea5-11eb-91e8-50681e4d831e.png)

Also shows implementations for `Self`:
![Code_eQj1pWfser](https://user-images.githubusercontent.com/3757771/103547892-43438180-4ea5-11eb-9122-461f2e0fdd01.png)


Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/hir/src/code_model.rs

@@ -1276,6 +1276,18 @@ pub fn ty(self, db: &dyn HirDatabase) -> Type {
         }
     }
 
+    pub fn trait_bounds(self, db: &dyn HirDatabase) -> Vec<Trait> {
+        db.generic_predicates_for_param(self.id)
+            .into_iter()
+            .filter_map(|pred| match &pred.value {
+                hir_ty::GenericPredicate::Implemented(trait_ref) => {
+                    Some(Trait::from(trait_ref.trait_))
+                }
+                _ => None,
+            })
+            .collect()
+    }
+
     pub fn default(self, db: &dyn HirDatabase) -> Option<Type> {
         let params = db.generic_defaults(self.id.parent);
         let local_idx = hir_ty::param_idx(db, self.id)?;
@@ -1343,6 +1355,12 @@ pub fn module(self, db: &dyn HirDatabase) -> Module {
     pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
         self.id.parent.into()
     }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let def = self.id.parent;
+        let krate = def.module(db.upcast()).krate;
+        Type::new(db, krate, def, db.const_param_ty(self.id))
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]

crates/ide/src/hover.rs

@@ -182,16 +182,18 @@ fn to_action(nav_target: NavigationTarget) -> HoverAction {
         })
     }
 
-    match def {
+    let adt = match def {
-        Definition::ModuleDef(it) => match it {
+        Definition::ModuleDef(ModuleDef::Trait(it)) => return it.try_to_nav(db).map(to_action),
-            ModuleDef::Adt(Adt::Struct(it)) => Some(to_action(it.try_to_nav(db)?)),
+        Definition::ModuleDef(ModuleDef::Adt(it)) => Some(it),
-            ModuleDef::Adt(Adt::Union(it)) => Some(to_action(it.try_to_nav(db)?)),
+        Definition::SelfType(it) => it.target_ty(db).as_adt(),
-            ModuleDef::Adt(Adt::Enum(it)) => Some(to_action(it.try_to_nav(db)?)),
-            ModuleDef::Trait(it) => Some(to_action(it.try_to_nav(db)?)),
-            _ => None,
-        },
         _ => None,
+    }?;
+    match adt {
+        Adt::Struct(it) => it.try_to_nav(db),
+        Adt::Union(it) => it.try_to_nav(db),
+        Adt::Enum(it) => it.try_to_nav(db),
     }
+    .map(to_action)
 }
 
 fn runnable_action(
@@ -226,8 +228,6 @@ fn runnable_action(
 }
 
 fn goto_type_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
-    match def {
-        Definition::Local(it) => {
     let mut targets: Vec<ModuleDef> = Vec::new();
     let mut push_new_def = |item: ModuleDef| {
         if !targets.contains(&item) {
@@ -235,7 +235,16 @@ fn goto_type_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
         }
     };
 
-            it.ty(db).walk(db, |t| {
+    if let Definition::TypeParam(it) = def {
+        it.trait_bounds(db).into_iter().for_each(|it| push_new_def(it.into()));
+    } else {
+        let ty = match def {
+            Definition::Local(it) => it.ty(db),
+            Definition::ConstParam(it) => it.ty(db),
+            _ => return None,
+        };
+
+        ty.walk(db, |t| {
             if let Some(adt) = t.as_adt() {
                 push_new_def(adt.into());
             } else if let Some(trait_) = t.as_dyn_trait() {
@@ -246,25 +255,19 @@ fn goto_type_action(db: &RootDatabase, def: Definition) -> Option<HoverAction> {
                 push_new_def(trait_.into());
             }
         });
+    }
 
     let targets = targets
         .into_iter()
         .filter_map(|it| {
             Some(HoverGotoTypeData {
-                        mod_path: render_path(
+                mod_path: render_path(db, it.module(db)?, it.name(db).map(|name| name.to_string())),
-                            db,
-                            it.module(db)?,
-                            it.name(db).map(|name| name.to_string()),
-                        ),
                 nav: it.try_to_nav(db)?,
             })
         })
         .collect();
 
     Some(HoverAction::GoToType(targets))
-        }
-        _ => None,
-    }
 }
 
 fn hover_markup(
@@ -2174,6 +2177,25 @@ fn test_hover_enum_has_impl_action() {
         );
     }
 
+    #[test]
+    fn test_hover_self_has_impl_action() {
+        check_actions(
+            r#"struct foo where Self<|>:;"#,
+            expect![[r#"
+                [
+                    Implementation(
+                        FilePosition {
+                            file_id: FileId(
+                                0,
+                            ),
+                            offset: 7,
+                        },
+                    ),
+                ]
+            "#]],
+        );
+    }
+
     #[test]
     fn test_hover_test_has_action() {
         check_actions(
@@ -3062,6 +3084,71 @@ fn test() -> impl Foo { S {} }
         );
     }
 
+    #[test]
+    fn test_hover_const_param_has_goto_type_action() {
+        check_actions(
+            r#"
+struct Bar;
+struct Foo<const BAR: Bar>;
+
+impl<const BAR: Bar> Foo<BAR<|>> {}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Bar",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        0,
+                                    ),
+                                    full_range: 0..11,
+                                    focus_range: 7..10,
+                                    name: "Bar",
+                                    kind: Struct,
+                                    description: "struct Bar",
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn test_hover_type_param_has_goto_type_action() {
+        check_actions(
+            r#"
+trait Foo {}
+
+fn foo<T: Foo>(t: T<|>){}
+"#,
+            expect![[r#"
+                [
+                    GoToType(
+                        [
+                            HoverGotoTypeData {
+                                mod_path: "test::Foo",
+                                nav: NavigationTarget {
+                                    file_id: FileId(
+                                        0,
+                                    ),
+                                    full_range: 0..12,
+                                    focus_range: 6..9,
+                                    name: "Foo",
+                                    kind: Trait,
+                                    description: "trait Foo",
+                                },
+                            },
+                        ],
+                    ),
+                ]
+            "#]],
+        );
+    }
+
     #[test]
     fn hover_displays_normalized_crate_names() {
         check(