// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. // error-pattern: cannot infer an appropriate lifetime extern mod extra; use extra::sync; fn main() { let x = ~sync::RWLock::new(); let mut y = None; x.write_downgrade(|write_mode| { y = Some(x.downgrade(write_mode)); }) // Adding this line causes a method unification failure instead // do (&option::unwrap(y)).read { } }