---

yaml
---
r: 187215
b: refs/heads/try
c: f0e9bd9
h: refs/heads/master
i:
  187213: 3ccf29f
  187211: 149f76f
  187207: fcbbf45
  187199: 00aba5a
v: v3

Author: flaper87

[refs]

@@ -2,7 +2,7 @@
 refs/heads/master: b4c965ee803a4521d8b4575f634e036f93e408f3
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 3a96d6a9818fe2affc98a187fb1065120458cee9
-refs/heads/try: d38aab397e3295ead5869f84cd54044c1759c6d7
+refs/heads/try: f0e9bd9099e729eb73b4483795d0057e963c8eac
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d
 refs/tags/release-0.2: c870d2dffb391e14efb05aa27898f1f6333a9596

branches/try/src/librustc/middle/traits/mod.rs

@@ -222,6 +222,9 @@ pub enum Vtable<'tcx, N> {
     VtableImpl(VtableImplData<'tcx, N>),
 
     /// Vtable for default trait implementations
+    /// This carries the information and nested obligations with regards
+    /// to a default implementation for a trait `Trait`. The nested obligations
+    /// ensure the trait implementation holds for all the constituent types.
     VtableDefaultImpl(VtableDefaultImplData<N>),
 
     /// Successful resolution to an obligation provided by the caller

branches/try/src/librustc/middle/traits/util.rs

@@ -323,8 +323,8 @@ pub fn trait_ref_for_builtin_bound<'tcx>(
     }
 }
 
+
 pub fn predicate_for_trait_ref<'tcx>(
-    tcx: &ty::ctxt<'tcx>,
     cause: ObligationCause<'tcx>,
     trait_ref: Rc<ty::TraitRef<'tcx>>,
     recursion_depth: uint)
@@ -349,7 +349,7 @@ pub fn predicate_for_default_trait_impl<'tcx>(
         def_id: trait_def_id,
         substs: tcx.mk_substs(Substs::empty().with_self_ty(param_ty))
     });
-    predicate_for_trait_ref(tcx, cause, trait_ref, recursion_depth)
+    predicate_for_trait_ref(cause, trait_ref, recursion_depth)
 }
 
 pub fn predicate_for_builtin_bound<'tcx>(
@@ -361,7 +361,7 @@ pub fn predicate_for_builtin_bound<'tcx>(
     -> Result<PredicateObligation<'tcx>, ErrorReported>
 {
     let trait_ref = try!(trait_ref_for_builtin_bound(tcx, builtin_bound, param_ty));
-    predicate_for_trait_ref(tcx, cause, trait_ref, recursion_depth)
+    predicate_for_trait_ref(cause, trait_ref, recursion_depth)
 }
 
 /// Cast a trait reference into a reference to one of its super