rust/src/test/compile-fail/issue-4335.rs

// Copyright 2012-2013 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(unboxed_closures)]
#![feature(box_syntax)]

fn id<T>(t: T) -> T { t }

fn f<'r, T>(v: &'r T) -> Box<FnMut() -> T + 'r> {
    id(box |&mut:| *v) //~ ERROR cannot infer
}

fn main() {
    let v = &5is;
    println!("{}", f(v).call_mut(()));
}