rust/src/test/compile-fail/issue-20261.rs

// 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 main() {
    // NB: this (almost) typechecks when default binding modes are enabled.
    for (ref i,) in [].iter() {
        //~^ ERROR non-reference pattern used to match a reference
        i.clone();
    }
}