syntax: Parses && as & & whenever appropriate.

Closes #11227.

src/test/run-pass/double-ref.rs

@@ -0,0 +1,41 @@
+// Copyright 2014 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.
+
+fn check_expr() {
+    let _:         & uint =     &1u;
+    let _:       & & uint =    &&1u;
+    let _:     & & & uint =   &&&1u;
+    let _:     & & & uint =  & &&1u;
+    let _:   & & & & uint =  &&&&1u;
+    let _:   & & & & uint = & &&&1u;
+    let _: & & & & & uint = &&&&&1u;
+}
+
+fn check_ty() {
+    let _:     &uint =         & 1u;
+    let _:    &&uint =       & & 1u;
+    let _:   &&&uint =     & & & 1u;
+    let _:  & &&uint =     & & & 1u;
+    let _:  &&&&uint =   & & & & 1u;
+    let _: & &&&uint =   & & & & 1u;
+    let _: &&&&&uint = & & & & & 1u;
+}
+
+fn check_pat() {
+    let     &_ =         & 1u;
+    let    &&_ =       & & 1u;
+    let   &&&_ =     & & & 1u;
+    let  & &&_ =     & & & 1u;
+    let  &&&&_ =   & & & & 1u;
+    let & &&&_ =   & & & & 1u;
+    let &&&&&_ = & & & & & 1u;
+}
+
+pub fn main() {}