Address review comments.

Author: michaelwoerister

src/librustc/ty/util.rs

@@ -513,7 +513,9 @@ impl<'a, 'gcx, 'tcx, W> TypeVisitor<'tcx> for TypeIdHasher<'a, 'gcx, 'tcx, W>
         match *r {
             ty::ReErased |
             ty::ReStatic |
-            ty::ReEmpty => {}
+            ty::ReEmpty => {
+                // No variant fields to hash for these ...
+            }
             ty::ReLateBound(db, ty::BrAnon(i)) => {
                 self.hash(db.depth);
                 self.hash(i);

src/librustc_mir/transform/erase_regions.rs

@@ -45,8 +45,17 @@ impl<'a, 'tcx> MutVisitor<'tcx> for EraseRegionsVisitor<'a, 'tcx> {
             Rvalue::Ref(ref mut r, _, _) => {
                 *r = self.tcx.mk_region(ReErased);
             }
-            _ => {
-                /* only the above variant contains regions */
+            Rvalue::Use(..) |
+            Rvalue::Repeat(..) |
+            Rvalue::Len(..) |
+            Rvalue::Cast(..) |
+            Rvalue::BinaryOp(..) |
+            Rvalue::CheckedBinaryOp(..) |
+            Rvalue::UnaryOp(..) |
+            Rvalue::Discriminant(..) |
+            Rvalue::Box(..) |
+            Rvalue::Aggregate(..) => {
+                // These variants don't contain regions.
             }
         }
         self.super_rvalue(rvalue, location);