Add regression test

src/test/compile-fail/issue-34171.rs

@@ -0,0 +1,21 @@
+// 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.
+
+#![feature(rustc_attrs)]
+
+macro_rules! null { ($i:tt) => {} }
+macro_rules! apply_null {
+    ($i:item) => { null! { $i } }
+}
+
+#[rustc_error]
+fn main() { //~ ERROR compilation successful
+    apply_null!(#[cfg(all())] fn f() {});
+}