rollup merge of #20554: huonw/mut-pattern

Conflicts:
	src/librustc_typeck/check/_match.rs

src/test/compile-fail/mut-pattern-internal-mutability.rs

@@ -0,0 +1,24 @@
+// Copyright 2015 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 main() {
+    let foo = &mut 1i;
+
+    let &mut x = foo;
+    x += 1; //~ ERROR re-assignment of immutable variable
+
+    // explicitly mut-ify internals
+    let &mut mut x = foo;
+    x += 1;
+
+    // check borrowing is detected successfully
+    let &mut ref x = foo;
+    *foo += 1; //~ ERROR cannot assign to `*foo` because it is borrowed
+}

src/test/compile-fail/mut-pattern-mismatched.rs

@@ -0,0 +1,26 @@
+// 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 main() {
+    let foo = &mut 1i;
+
+    // (separate lines to ensure the spans are accurate)
+
+    // SNAP c894171 uncomment this after the next snapshot
+    // NOTE(stage0) just in case tidy doesn't check SNAP's in tests
+    // let &_ // ~ ERROR expected `&mut int`, found `&_`
+    //    = foo;
+    let &mut _ = foo;
+
+    let bar = &1i;
+    let &_ = bar;
+    let &mut _ //~ ERROR expected `&int`, found `&mut _`
+         = bar;
+}