From eaaf3f67ab1a4dfa2881328bd4614bb005f0748d Mon Sep 17 00:00:00 2001
From: John Barker <jebarker@gmail.com>
Date: Sun, 7 Jul 2013 22:26:15 -0400
Subject: [PATCH] Always eat up mut when parsing general args, fixes #7483

---
 src/libsyntax/parse/parser.rs                  |  4 ++--
 src/test/run-pass/traits-default-method-mut.rs | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 src/test/run-pass/traits-default-method-mut.rs

diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 8666c84bbef..e8e7828e465 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -1074,10 +1074,9 @@ impl Parser {
     // This version of parse arg doesn't necessarily require
     // identifier names.
     pub fn parse_arg_general(&self, require_name: bool) -> arg {
-        let mut is_mutbl = false;
+        let mut is_mutbl = self.eat_keyword(keywords::Mut);
         let pat = if require_name || self.is_named_argument() {
             self.parse_arg_mode();
-            is_mutbl = self.eat_keyword(keywords::Mut);
             let pat = self.parse_pat();
 
             if is_mutbl && !ast_util::pat_is_ident(pat) {
@@ -1087,6 +1086,7 @@ impl Parser {
             self.expect(&token::COLON);
             pat
         } else {
+            is_mutbl = false;
             ast_util::ident_to_pat(self.get_id(),
                                    *self.last_span,
                                    special_idents::invalid)
diff --git a/src/test/run-pass/traits-default-method-mut.rs b/src/test/run-pass/traits-default-method-mut.rs
new file mode 100644
index 00000000000..a36f0178c15
--- /dev/null
+++ b/src/test/run-pass/traits-default-method-mut.rs
@@ -0,0 +1,17 @@
+// 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.
+
+#[allow(default_methods)];
+
+trait Foo {
+    fn foo(mut v: int) { v = 1; }
+}
+
+fn main() {}