Fix freezing of @mut Objects when passing as argument

src/test/run-fail/borrowck-wg-fail-object-arg.rs

@@ -0,0 +1,22 @@
+// error-pattern:borrowed
+
+trait Foo {
+    fn foo(&self, @mut int);
+}
+
+impl Foo for int {
+    fn foo(&self, x: @mut int) {
+        *x += *self;
+    }
+}
+
+fn it_takes_two(f: &Foo, g: &mut Foo) {
+}
+
+fn main() {
+    let x = @mut 3_i;
+    let y = x as @mut Foo;
+    let z = y;
+
+    it_takes_two(y, z);
+}

src/test/run-pass/objects-coerce-from-managed-to-borrowed.rs

@@ -0,0 +1,44 @@
+// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that we can coerce an `@Object` to an `&Object`
+
+trait Foo {
+    fn foo(&self) -> uint;
+    fn bar(&mut self) -> uint;
+}
+
+impl Foo for uint {
+    fn foo(&self) -> uint {
+        *self
+    }
+
+    fn bar(&mut self) -> uint {
+        *self += 1;
+        *self
+    }
+}
+
+fn do_it_mut(obj: &mut Foo) {
+    let x = obj.bar();
+    let y = obj.foo();
+    assert_eq!(x, y);
+}
+
+fn do_it_imm(obj: &Foo, v: uint) {
+    let y = obj.foo();
+    assert_eq!(v, y);
+}
+
+fn main() {
+    let x = @mut 22u as @mut Foo;
+    do_it_mut(x);
+    do_it_imm(x, 23u);
+}