added function to check if lints belong to an external macro

src/test/ui/in-band-lifetimes/ellided-lifetimes-macro-checks.rs

@@ -0,0 +1,15 @@
+// Copyright 2018 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(nll)]
+#![deny(elided_lifetime_in_path)]
+
+fn main() {
+    format!("foo {}", 22)
+}