Add regression test.

src/test/run-pass/issue-34932.rs

@@ -0,0 +1,23 @@
+// 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:--test
+// rustc-env:RUSTC_BOOTSTRAP_KEY=
+// ignore-pretty : (#23623) problems when  ending with // comments
+
+#![cfg(any())] // This test should be configured away
+#![feature(rustc_attrs)] // Test that this is allowed on stable/beta
+#![feature(iter_arith_traits)] // Test that this is not unused
+#![deny(unused_features)]
+
+#[test]
+fn dummy() {
+    let () = "this should not reach type-checking";
+}