---

yaml
---
r: 163655
b: refs/heads/snap-stage3
c: 89922e5
h: refs/heads/master
i:
  163653: 84cd2a7
  163651: d2a8038
  163647: adaac22
v: v3

Author: nikomatsakis

[refs]

@@ -1,7 +1,7 @@
 ---
 refs/heads/master: 9146a919b616e39e528e4d7100d16eef52f1f852
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
-refs/heads/snap-stage3: 1085012cd2f587bed0eb64a547d03d671d3a5c6f
+refs/heads/snap-stage3: 89922e52b06fbe1af74983cf2f936c5bf9e6d91e
 refs/heads/try: 20cbbffeefc1f35e2ea63afce7b42fbd79611d42
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105
 refs/heads/dist-snap: ba4081a5a8573875fed17545846f6f6902c8ba8d

branches/snap-stage3/src/librustc/middle/ty.rs

@@ -1368,12 +1368,13 @@ impl<'tcx> PolyTraitRef<'tcx> {
     }
 }
 
-/// Binder serves as a synthetic binder for lifetimes. It is used when
-/// we wish to replace the escaping higher-ranked lifetimes in a type
-/// or something else that is not itself a binder (this is because the
-/// `replace_late_bound_regions` function replaces all lifetimes bound
-/// by the binder supplied to it; but a type is not a binder, so you
-/// must introduce an artificial one).
+/// Binder is a binder for higher-ranked lifetimes. It is part of the
+/// compiler's representation for things like `for<'a> Fn(&'a int)`
+/// (which would be represented by the type `PolyTraitRef ==
+/// Binder<TraitRef>`). Note that when we skolemize, instantiate,
+/// erase, or otherwise "discharge" these bound reons, we change the
+/// type from `Binder<T>` to just `T` (see
+/// e.g. `liberate_late_bound_regions`).
 #[deriving(Clone, PartialEq, Eq, Hash, Show)]
 pub struct Binder<T>(pub T);