---

yaml
---
r: 185749
b: refs/heads/auto
c: f0e9bd9
h: refs/heads/master
i:
  185747: 639c8b6
v: v3

Author: flaper87

[refs]

@@ -10,7 +10,7 @@ refs/tags/release-0.3: b5f0d0f648d9a6153664837026ba1be43d3e2503
 refs/tags/release-0.3.1: 495bae036dfe5ec6ceafd3312b4dca48741e845b
 refs/tags/release-0.4: e828ea2080499553b97dfe33b3f4d472b4562ad7
 refs/tags/release-0.5: 7e3bcfbf21278251ee936ad53e92e9b719702d73
-refs/heads/auto: d38aab397e3295ead5869f84cd54044c1759c6d7
+refs/heads/auto: f0e9bd9099e729eb73b4483795d0057e963c8eac
 refs/heads/servo: af82457af293e2a842ba6b7759b70288da276167
 refs/tags/release-0.6: b4ebcfa1812664df5e142f0134a5faea3918544c
 refs/tags/0.1: b19db808c2793fe2976759b85a355c3ad8c8b336

branches/auto/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/auto/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