---

yaml
---
r: 185019
b: refs/heads/snap-stage3
c: e8df95d
h: refs/heads/master
i:
  185017: 30040a2
  185015: b655def
v: v3

Author: nikomatsakis

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: f0f7ca27de6b4e03f30012656dad270cda55a363
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 24bdce4bbf55dd7f88492fd3a106bca2efdaa1a6
+refs/heads/snap-stage3: e8df95d77f65a3a1456f7e10d9d1dd209acf2879
 refs/heads/try: ccf8fedf1cffcb8f6f3581d53d220039e192fe77
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d

branches/snap-stage3/src/librustc/middle/traits/select.rs

@@ -1143,8 +1143,13 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
 
         match self_ty.sty {
-            ty::ty_infer(ty::TyVar(_)) |
             ty::ty_trait(..) => {},
+            ty::ty_infer(ty::TyVar(_)) => {
+                // the defaulted impl might apply, we don't know
+                if ty::trait_has_default_impl(self.tcx(), def_id) {
+                    candidates.ambiguous = true;
+                }
+            }
             _ => {
                 if ty::trait_has_default_impl(self.tcx(), def_id) {
                     candidates.vec.push(DefaultImplCandidate(def_id.clone()))