Add test for issue #16994.

src/test/compile-fail/issue-16994.rs

@@ -0,0 +1,20 @@
+// Copyright 2017 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)]
+
+fn cb<'a,T>(_x: Box<Fn((&'a i32, &'a (Vec<&'static i32>, bool))) -> T>) -> T {
+    panic!()
+}
+
+#[rustc_error]
+fn main() { //~ ERROR compilation successful
+    cb(Box::new(|(k, &(ref v, b))| (*k, v.clone(), b)));
+}