rust/src/test/run-pass/alt-ref-binding-mut.rs

// Copyright 2012 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.

type rec = {
    f: int
};

fn destructure(x: &mut rec) {
    match *x {
      {f: ref mut f} => *f += 1
    }
}

fn main() {
    let mut v = {f: 22};
    destructure(&mut v);
    assert v.f == 23;
}