auto merge of #7658 : excepttheweasel/rust/mut_default_param_list_issue_7483, r=pcwalton

src/test/run-pass/traits-default-method-mut.rs

@@ -0,0 +1,17 @@
+// Copyright 2013 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.
+
+#[allow(default_methods)];
+
+trait Foo {
+    fn foo(&self, mut v: int) { v = 1; }
+}
+
+fn main() {}