3 files changed, 49 insertions, 9 deletions

diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 3719f76a6..5c56c2eb0 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -28,8 +28,8 @@ use hir_def::{
     path::{path, Path},
     resolver::{HasResolver, Resolver, TypeNs},
     type_ref::{Mutability, TypeRef},
-    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, FunctionId, TraitId, TypeAliasId,
-    VariantId,
+    AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, FunctionId, Lookup, TraitId,
+    TypeAliasId, VariantId,
 };
 use hir_expand::{diagnostics::DiagnosticSink, name::name};
 use ra_arena::map::ArenaMap;
@@ -376,17 +376,21 @@ impl<'a> InferenceContext<'a> {
     ) -> Ty {
         match assoc_ty {
             Some(res_assoc_ty) => {
+                let trait_ = match res_assoc_ty.lookup(self.db.upcast()).container {
+                    hir_def::AssocContainerId::TraitId(trait_) => trait_,
+                    _ => panic!("resolve_associated_type called with non-associated type"),
+                };
                 let ty = self.table.new_type_var();
-                let builder = Substs::build_for_def(self.db, res_assoc_ty)
+                let substs = Substs::build_for_def(self.db, res_assoc_ty)
                     .push(inner_ty)
-                    .fill(params.iter().cloned());
+                    .fill(params.iter().cloned())
+                    .build();
+                let trait_ref = TraitRef { trait_, substs: substs.clone() };
                 let projection = ProjectionPredicate {
                     ty: ty.clone(),
-                    projection_ty: ProjectionTy {
-                        associated_ty: res_assoc_ty,
-                        parameters: builder.build(),
-                    },
+                    projection_ty: ProjectionTy { associated_ty: res_assoc_ty, parameters: substs },
                 };
+                self.obligations.push(Obligation::Trait(trait_ref));
                 self.obligations.push(Obligation::Projection(projection));
                 self.resolve_ty_as_possible(ty)
             }
diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs
index 766790576..529d9e253 100644
--- a/crates/ra_hir_ty/src/tests/traits.rs
+++ b/crates/ra_hir_ty/src/tests/traits.rs
@@ -541,6 +541,42 @@ mod ops {
 }
 
 #[test]
+fn infer_ops_index_int() {
+    check_types(
+        r#"
+//- /main.rs crate:main deps:std
+struct Bar;
+struct Foo;
+
+impl std::ops::Index<u32> for Bar {
+    type Output = Foo;
+}
+
+struct Range;
+impl std::ops::Index<Range> for Bar {
+    type Output = Bar;
+}
+
+fn test() {
+    let a = Bar;
+    let b = a[1];
+    b;
+  //^ Foo
+}
+
+//- /std.rs crate:std
+#[prelude_import] use ops::*;
+mod ops {
+    #[lang = "index"]
+    pub trait Index<Idx> {
+        type Output;
+    }
+}
+"#,
+    );
+}
+
+#[test]
 fn infer_ops_index_autoderef() {
     check_types(
         r#"
diff --git a/editors/code/package.json b/editors/code/package.json
index 7c8b2fbec..4b47fc9d3 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -583,7 +583,7 @@
                     "items": {
                         "type": "string"
                     },
-                    "description": "List of warnings warnings that should be displayed with hint severity.\nThe warnings will be indicated by faded text or three dots in code and will not show up in te problems panel.",
+                    "description": "List of warnings warnings that should be displayed with hint severity.\nThe warnings will be indicated by faded text or three dots in code and will not show up in the problems panel.",
                     "default": []
                 }
             }