rust/src/test/compile-fail/issue-25439.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.

struct Helper<'a, F: 'a>(&'a F);

fn fix<F>(f: F) -> i32 where F: Fn(Helper<F>, i32) -> i32 {
    f(Helper(&f), 8)
}

fn main() {
    fix(|_, x| x); //~ ERROR mismatched types
}