Extend temporary lifetimes if there is a ref in an enum binding

too.

Previously I had omitted this case since function calls don't get the same
treatment on the RHS, but it's different on the pattern and is more consistent
-- the goal is to identify `let` statements where `ref` bindings create
interior pointers.

Author: nikomatsakis

src/librustc/middle/region.rs

@@ -637,6 +637,7 @@ fn resolve_local(visitor: &mut RegionResolutionVisitor,
          *
          *     P& = ref X
          *        | StructName { ..., P&, ... }
+         *        | VariantName(..., P&, ...)
          *        | [ ..., P&, ... ]
          *        | ( ..., P&, ... )
          *        | ~P&
@@ -656,6 +657,7 @@ fn resolve_local(visitor: &mut RegionResolutionVisitor,
                 pats3.iter().any(|&p| is_binding_pat(p))
             }
 
+            ast::PatEnum(_, Some(ref subpats)) |
             ast::PatTup(ref subpats) => {
                 subpats.iter().any(|&p| is_binding_pat(p))
             }