rust/src/test/run-pass/issue-8398.rs

// Copyright 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.

// pretty-expanded FIXME #23616

pub trait Writer {
    fn write(&mut self, b: &[u8]) -> Result<(), ()>;
}

fn foo(a: &mut Writer) {
    a.write(&[]).unwrap();
}

pub fn main(){}