Implement field shorthands in struct literal expressions.

src/test/parse-fail/struct-field-numeric-shorthand.rs

@@ -0,0 +1,19 @@
+// Copyright 2016 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.
+
+// compile-flags: -Z parse-only
+
+#![feature(field_init_shorthand)]
+
+struct Rgb(u8, u8, u8);
+
+fn main() {
+    let _ = Rgb { 0, 1, 2 }; //~ ERROR expected identifier, found `0`
+}