2 files changed, 40 insertions, 25 deletions

diff --git a/crates/hir_def/src/path/lower.rs b/crates/hir_def/src/path/lower.rs
index 5d5dd9c8f..54ede7393 100644
--- a/crates/hir_def/src/path/lower.rs
+++ b/crates/hir_def/src/path/lower.rs
@@ -205,15 +205,14 @@ fn lower_generic_args_from_fn_path(
 ) -> Option<GenericArgs> {
     let mut args = Vec::new();
     let mut bindings = Vec::new();
-    if let Some(params) = params {
-        let mut param_types = Vec::new();
-        for param in params.params() {
-            let type_ref = TypeRef::from_ast_opt(&ctx, param.ty());
-            param_types.push(type_ref);
-        }
-        let arg = GenericArg::Type(TypeRef::Tuple(param_types));
-        args.push(arg);
+    let params = params?;
+    let mut param_types = Vec::new();
+    for param in params.params() {
+        let type_ref = TypeRef::from_ast_opt(&ctx, param.ty());
+        param_types.push(type_ref);
     }
+    let arg = GenericArg::Type(TypeRef::Tuple(param_types));
+    args.push(arg);
     if let Some(ret_type) = ret_type {
         let type_ref = TypeRef::from_ast_opt(&ctx, ret_type.ty());
         bindings.push(AssociatedTypeBinding {
@@ -221,10 +220,14 @@ fn lower_generic_args_from_fn_path(
             type_ref: Some(type_ref),
             bounds: Vec::new(),
         });
-    }
-    if args.is_empty() && bindings.is_empty() {
-        None
     } else {
-        Some(GenericArgs { args, has_self_type: false, bindings })
+        // -> ()
+        let type_ref = TypeRef::Tuple(Vec::new());
+        bindings.push(AssociatedTypeBinding {
+            name: name![Output],
+            type_ref: Some(type_ref),
+            bounds: Vec::new(),
+        });
     }
+    Some(GenericArgs { args, has_self_type: false, bindings })
 }
diff --git a/crates/hir_def/src/resolver.rs b/crates/hir_def/src/resolver.rs
index 0391cc49b..fb8a6f260 100644
--- a/crates/hir_def/src/resolver.rs
+++ b/crates/hir_def/src/resolver.rs
@@ -337,22 +337,34 @@ impl Resolver {
     pub fn traits_in_scope(&self, db: &dyn DefDatabase) -> FxHashSet<TraitId> {
         let mut traits = FxHashSet::default();
         for scope in &self.scopes {
-            if let Scope::ModuleScope(m) = scope {
-                if let Some(prelude) = m.def_map.prelude() {
-                    let prelude_def_map = prelude.def_map(db);
-                    traits.extend(prelude_def_map[prelude.local_id].scope.traits());
-                }
-                traits.extend(m.def_map[m.module_id].scope.traits());
-
-                // Add all traits that are in scope because of the containing DefMaps
-                m.def_map.with_ancestor_maps(db, m.module_id, &mut |def_map, module| {
-                    if let Some(prelude) = def_map.prelude() {
+            match scope {
+                Scope::ModuleScope(m) => {
+                    if let Some(prelude) = m.def_map.prelude() {
                         let prelude_def_map = prelude.def_map(db);
                         traits.extend(prelude_def_map[prelude.local_id].scope.traits());
                     }
-                    traits.extend(def_map[module].scope.traits());
-                    None::<()>
-                });
+                    traits.extend(m.def_map[m.module_id].scope.traits());
+
+                    // Add all traits that are in scope because of the containing DefMaps
+                    m.def_map.with_ancestor_maps(db, m.module_id, &mut |def_map, module| {
+                        if let Some(prelude) = def_map.prelude() {
+                            let prelude_def_map = prelude.def_map(db);
+                            traits.extend(prelude_def_map[prelude.local_id].scope.traits());
+                        }
+                        traits.extend(def_map[module].scope.traits());
+                        None::<()>
+                    });
+                }
+                &Scope::ImplDefScope(impl_) => {
+                    if let Some(target_trait) = &db.impl_data(impl_).target_trait {
+                        if let Some(TypeNs::TraitId(trait_)) =
+                            self.resolve_path_in_type_ns_fully(db, target_trait.path.mod_path())
+                        {
+                            traits.insert(trait_);
+                        }
+                    }
+                }
+                _ => (),
             }
         }
         traits