add test for #21655

closes #21655

src/test/run-pass/issue-21655.rs

@@ -0,0 +1,20 @@
+// Copyright 2015 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.
+
+fn test(it: &mut Iterator<Item=i32>) {
+    for x in it {
+        assert_eq!(x, 1)
+    }
+}
+
+fn main() {
+    let v = vec![1];
+    test(&mut v.into_iter())
+}