---

yaml
---
r: 192976
b: refs/heads/beta
c: e8df95d
h: refs/heads/master
v: v3

Author: nikomatsakis

[refs]

@@ -31,7 +31,7 @@ refs/heads/automation-fail: 1bf06495443584539b958873e04cc2f864ab10e4
 refs/heads/issue-18208-method-dispatch-3-quick-reject: 2009f85b9f99dedcec4404418eda9ddba90258a2
 refs/heads/batch: b7fd822592a4fb577552d93010c4a4e14f314346
 refs/heads/building: 126db549b038c84269a1e4fe46f051b2c15d6970
-refs/heads/beta: 24bdce4bbf55dd7f88492fd3a106bca2efdaa1a6
+refs/heads/beta: e8df95d77f65a3a1456f7e10d9d1dd209acf2879
 refs/heads/windistfix: 7608dbad651f02e837ed05eef3d74a6662a6e928
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
 refs/heads/tmp: de8a23bbc3a7b9cbd7574b5b91a34af59bf030e6

branches/beta/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()))