3 files changed, 27 insertions, 25 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 50e6409b1..9578c20b0 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -28,8 +28,8 @@ use crate::{
     expr::{BindingAnnotation, Body, BodySourceMap, ExprValidator, Pat, PatId},
     ty::display::HirFormatter,
     ty::{
-        self, utils::all_super_traits, InEnvironment, InferenceResult, Namespace, TraitEnvironment,
-        TraitRef, Ty, TypeCtor, TypeWalk,
+        self, InEnvironment, InferenceResult, Namespace, TraitEnvironment, TraitRef, Ty, TypeCtor,
+        TypeWalk,
     },
     CallableDef, Either, HirDisplay, Name, Source,
 };
@@ -740,17 +740,6 @@ impl Trait {
         db.trait_data(self.id).items.iter().map(|(_name, it)| (*it).into()).collect()
     }
 
-    pub fn associated_type_by_name_including_super_traits(
-        self,
-        db: &impl HirDatabase,
-        name: &Name,
-    ) -> Option<TypeAlias> {
-        all_super_traits(db, self.id)
-            .into_iter()
-            .find_map(|t| db.trait_data(t).associated_type_by_name(name))
-            .map(TypeAlias::from)
-    }
-
     pub fn trait_ref(self, db: &impl HirDatabase) -> TraitRef {
         TraitRef::for_trait(db, self)
     }
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index 0ac7920bb..805a73ff5 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -28,7 +28,7 @@ use crate::{
     db::HirDatabase,
     ty::{
         primitive::{FloatTy, IntTy},
-        utils::all_super_traits,
+        utils::{all_super_traits, associated_type_by_name_including_super_traits},
         Adt,
     },
     util::make_mut_slice,
@@ -170,14 +170,16 @@ impl Ty {
                 );
                 return if remaining_segments.len() == 1 {
                     let segment = &remaining_segments[0];
-                    match trait_ref
-                        .trait_
-                        .associated_type_by_name_including_super_traits(db, &segment.name)
-                    {
+                    let associated_ty = associated_type_by_name_including_super_traits(
+                        db,
+                        trait_ref.trait_.id,
+                        &segment.name,
+                    );
+                    match associated_ty {
                         Some(associated_ty) => {
                             // FIXME handle type parameters on the segment
                             Ty::Projection(ProjectionTy {
-                                associated_ty: associated_ty.id,
+                                associated_ty,
                                 parameters: trait_ref.substs,
                             })
                         }
@@ -508,10 +510,11 @@ fn assoc_type_bindings_from_type_bound<'a>(
         .flat_map(|args_and_bindings| args_and_bindings.bindings.iter())
         .map(move |(name, type_ref)| {
             let associated_ty =
-                match trait_ref.trait_.associated_type_by_name_including_super_traits(db, &name) {
-                    None => return GenericPredicate::Error,
-                    Some(t) => t.id,
-                };
+                associated_type_by_name_including_super_traits(db, trait_ref.trait_.id, &name);
+            let associated_ty = match associated_ty {
+                None => return GenericPredicate::Error,
+                Some(t) => t,
+            };
             let projection_ty =
                 ProjectionTy { associated_ty, parameters: trait_ref.substs.clone() };
             let ty = Ty::from_hir(db, resolver, type_ref);
diff --git a/crates/ra_hir/src/ty/utils.rs b/crates/ra_hir/src/ty/utils.rs
index 672804787..52994b9e3 100644
--- a/crates/ra_hir/src/ty/utils.rs
+++ b/crates/ra_hir/src/ty/utils.rs
@@ -5,9 +5,9 @@ use hir_def::{
     db::DefDatabase,
     resolver::{HasResolver, TypeNs},
     type_ref::TypeRef,
-    TraitId,
+    TraitId, TypeAliasId,
 };
-use hir_expand::name;
+use hir_expand::name::{self, Name};
 
 // FIXME: this is wrong, b/c it can't express `trait T: PartialEq<()>`.
 // We should return a `TraitREf` here.
@@ -51,3 +51,13 @@ pub(crate) fn all_super_traits(db: &impl DefDatabase, trait_: TraitId) -> Vec<Tr
     }
     result
 }
+
+pub(crate) fn associated_type_by_name_including_super_traits(
+    db: &impl DefDatabase,
+    trait_: TraitId,
+    name: &Name,
+) -> Option<TypeAliasId> {
+    all_super_traits(db, trait_)
+        .into_iter()
+        .find_map(|t| db.trait_data(t).associated_type_by_name(name))
+}