made the add_missing_impl_members and add_missing_default_members assists transform default generic types

crates/ide-assists/src/handlers/add_missing_impl_members.rs

@@ -830,6 +830,115 @@ impl Foo<T> for S<T> {
         )
     }
 
+    #[test]
+    fn test_qualify_generic_default_parameter() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+mod m {
+    pub struct S;
+    pub trait Foo<T = S> {
+        fn bar(&self, other: &T);
+    }
+}
+
+struct S;
+impl m::Foo for S { $0 }"#,
+            r#"
+mod m {
+    pub struct S;
+    pub trait Foo<T = S> {
+        fn bar(&self, other: &T);
+    }
+}
+
+struct S;
+impl m::Foo for S {
+    fn bar(&self, other: &m::S) {
+        ${0:todo!()}
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_qualify_generic_default_parameter_2() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+mod m {
+    pub struct Wrapper<T, V> {
+        one: T,
+        another: V
+    };
+    pub struct S;
+    pub trait Foo<T = Wrapper<S, bool>> {
+        fn bar(&self, other: &T);
+    }
+}
+
+struct S;
+impl m::Foo for S { $0 }"#,
+            r#"
+mod m {
+    pub struct Wrapper<T, V> {
+        one: T,
+        another: V
+    };
+    pub struct S;
+    pub trait Foo<T = Wrapper<S, bool>> {
+        fn bar(&self, other: &T);
+    }
+}
+
+struct S;
+impl m::Foo for S {
+    fn bar(&self, other: &m::Wrapper<m::S, bool>) {
+        ${0:todo!()}
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_qualify_generic_default_parameter_3() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+mod m {
+    pub struct Wrapper<T, V> {
+        one: T,
+        another: V
+    };
+    pub struct S;
+    pub trait Foo<T = S, V = Wrapper<T, S>> {
+        fn bar(&self, other: &V);
+    }
+}
+
+struct S;
+impl m::Foo for S { $0 }"#,
+            r#"
+mod m {
+    pub struct Wrapper<T, V> {
+        one: T,
+        another: V
+    };
+    pub struct S;
+    pub trait Foo<T = S, V = Wrapper<T, S>> {
+        fn bar(&self, other: &V);
+    }
+}
+
+struct S;
+impl m::Foo for S {
+    fn bar(&self, other: &m::Wrapper<m::S, m::S>) {
+        ${0:todo!()}
+    }
+}"#,
+        );
+    }
+
     #[test]
     fn test_assoc_type_bounds_are_removed() {
         check_assist(

crates/ide-db/src/path_transform.rs

@@ -17,6 +17,11 @@ struct AstSubsts {
     lifetimes: Vec<ast::LifetimeArg>,
 }
 
+struct TypeOrConstSubst {
+    subst: ast::Type,
+    to_be_transformed: bool,
+}
+
 type LifetimeName = String;
 
 /// `PathTransform` substitutes path in SyntaxNodes in bulk.
@@ -123,13 +128,21 @@ impl<'a> PathTransform<'a> {
             // the resulting change can be applied correctly.
             .zip(self.substs.types_and_consts.iter().map(Some).chain(std::iter::repeat(None)))
             .filter_map(|(k, v)| match (k.split(db), v) {
-                (_, Some(v)) => Some((k, v.ty()?.clone())),
+                (_, Some(v)) => {
+                    let subst =
+                        TypeOrConstSubst { subst: v.ty()?.clone(), to_be_transformed: false };
+                    Some((k, subst))
+                }
                 (Either::Right(t), None) => {
                     let default = t.default(db)?;
-                    let v = ast::make::ty(
+                    let subst = TypeOrConstSubst {
+                        subst: ast::make::ty(
                             &default.display_source_code(db, source_module.into(), false).ok()?,
-                    );
+                        )
-                    Some((k, v))
+                        .clone_for_update(),
+                        to_be_transformed: true,
+                    };
+                    Some((k, subst))
                 }
                 (Either::Left(_), None) => None, // FIXME: get default const value
             })
@@ -151,43 +164,42 @@ impl<'a> PathTransform<'a> {
 }
 
 struct Ctx<'a> {
-    type_and_const_substs: FxHashMap<hir::TypeOrConstParam, ast::Type>,
+    type_and_const_substs: FxHashMap<hir::TypeOrConstParam, TypeOrConstSubst>,
     lifetime_substs: FxHashMap<LifetimeName, ast::Lifetime>,
     target_module: hir::Module,
     source_scope: &'a SemanticsScope<'a>,
 }
 
-impl<'a> Ctx<'a> {
+fn preorder(item: &SyntaxNode) -> impl Iterator<Item = SyntaxNode> {
-    fn apply(&self, item: &SyntaxNode) {
+    item.preorder().filter_map(|event| match event {
-        // `transform_path` may update a node's parent and that would break the
-        // tree traversal. Thus all paths in the tree are collected into a vec
-        // so that such operation is safe.
-        let paths = item
-            .preorder()
-            .filter_map(|event| match event {
         syntax::WalkEvent::Enter(_) => None,
         syntax::WalkEvent::Leave(node) => Some(node),
     })
-            .filter_map(ast::Path::cast)
+}
-            .collect::<Vec<_>>();
 
+impl<'a> Ctx<'a> {
+    fn apply(&self, item: &SyntaxNode) {
+        for (_, subst) in &self.type_and_const_substs {
+            if subst.to_be_transformed {
+                let paths =
+                    preorder(&subst.subst.syntax()).filter_map(ast::Path::cast).collect::<Vec<_>>();
+                for path in paths {
+                    self.transform_path(path);
+                }
+            }
+        }
+
+        // `transform_path` may update a node's parent and that would break the
+        // tree traversal. Thus all paths in the tree are collected into a vec
+        // so that such operation is safe.
+        let paths = preorder(item).filter_map(ast::Path::cast).collect::<Vec<_>>();
         for path in paths {
             self.transform_path(path);
         }
 
-        item.preorder()
+        preorder(item).filter_map(ast::Lifetime::cast).for_each(|lifetime| {
-            .filter_map(|event| match event {
+            if let Some(subst) = self.lifetime_substs.get(&lifetime.syntax().text().to_string()) {
-                syntax::WalkEvent::Enter(_) => None,
+                ted::replace(lifetime.syntax(), subst.clone_subtree().clone_for_update().syntax());
-                syntax::WalkEvent::Leave(node) => Some(node),
-            })
-            .filter_map(ast::Lifetime::cast)
-            .for_each(|lifetime| {
-                if let Some(subst) = self.lifetime_substs.get(&lifetime.syntax().text().to_string())
-                {
-                    ted::replace(
-                        lifetime.syntax(),
-                        subst.clone_subtree().clone_for_update().syntax(),
-                    );
             }
         });
     }
@@ -208,7 +220,9 @@ impl<'a> Ctx<'a> {
 
         match resolution {
             hir::PathResolution::TypeParam(tp) => {
-                if let Some(subst) = self.type_and_const_substs.get(&tp.merge()) {
+                if let Some(TypeOrConstSubst { subst, .. }) =
+                    self.type_and_const_substs.get(&tp.merge())
+                {
                     let parent = path.syntax().parent()?;
                     if let Some(parent) = ast::Path::cast(parent.clone()) {
                         // Path inside path means that there is an associated
@@ -276,7 +290,9 @@ impl<'a> Ctx<'a> {
                 ted::replace(path.syntax(), res.syntax())
             }
             hir::PathResolution::ConstParam(cp) => {
-                if let Some(subst) = self.type_and_const_substs.get(&cp.merge()) {
+                if let Some(TypeOrConstSubst { subst, .. }) =
+                    self.type_and_const_substs.get(&cp.merge())
+                {
                     ted::replace(path.syntax(), subst.clone_subtree().clone_for_update().syntax());
                 }
             }