rustc: Fix type_need_unwind_cleanup. Closes #2272

Author: brson

src/rustc/middle/ty.rs

@@ -1176,7 +1176,8 @@ fn type_needs_unwind_cleanup_(cx: ctxt, ty: t,
     let mut encountered_box = encountered_box;
     let mut needs_unwind_cleanup = false;
     maybe_walk_ty(ty) {|ty|
-        alt get(ty).struct {
+        let old_encountered_box = encountered_box;
+        let result = alt get(ty).struct {
           ty_box(_) | ty_opaque_box {
             encountered_box = true;
             true
@@ -1216,7 +1217,10 @@ fn type_needs_unwind_cleanup_(cx: ctxt, ty: t,
             needs_unwind_cleanup = true;
             false
           }
-        }
+        };
+
+        encountered_box = old_encountered_box;
+        result
     }
 
     ret needs_unwind_cleanup;

src/test/compile-fail/class-implements-int.rs

@@ -1,10 +1,3 @@
-// xfail-test
-/*
-  tjc: currently this results in a memory leak after a call to
-  span_fatal in typeck. I think it's the same issue as #2272, because
-  if I make type_needs_unwind_cleanup always return true, the test passes.
-  FIXME: Un-xfail this when #2272 is fixed.
- */
 class cat implements int { //! ERROR can only implement interface types
   let meows: uint;
   new(in_x : uint) { self.meows = in_x; }

src/test/compile-fail/infinite-instantiation.rs

@@ -1,7 +1,5 @@
 // error-pattern: overly deep expansion
 // issue 2258
-// This is currently exposing a memory leak, and xfailed for that reason
-// xfail-test
 
 iface to_opt {
     fn to_option() -> option<self>;

src/test/run-fail/issue-2272.rs

@@ -0,0 +1,12 @@
+// error-pattern:explicit failure
+// Issue #2272 - unwind this without leaking the unique pointer
+
+fn main() {
+    let _x = {
+        y: {
+            z: @0
+        },
+        a: ~0
+    };
+    fail;
+}