Partially stabilize RFC 1506 "Clarify relationships between ADTs"

src/test/compile-fail/numeric-fields-feature-gate.rs

@@ -0,0 +1,18 @@
+// 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.
+
+struct S(u8);
+
+fn main() {
+    let s = S{0: 10}; //~ ERROR numeric fields in struct expressions are unstable
+    match s {
+        S{0: a, ..} => {} //~ ERROR numeric fields in struct patterns are unstable
+    }
+}