| // Copyright 2014 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. |
| |
| // A basic test of using a higher-ranked trait bound. |
| |
| trait FnLike<A,R> { |
| fn call(&self, arg: A) -> R; |
| } |
| |
| type FnObject<'b> = for<'a> FnLike<(&'a i32,), &'a i32> + 'b; |
| |
| struct Identity; |
| |
| impl<'a, T> FnLike<(&'a T,), &'a T> for Identity { |
| fn call(&self, (arg,): (&'a T,)) -> &'a T { |
| arg |
| } |
| } |
| |
| fn call_repeatedly(f: &FnObject) { |
| let x = 3; |
| let y = f.call((&x,)); |
| assert_eq!(3, *y); |
| } |
| |
| fn main() { |
| call_repeatedly(&Identity); |
| } |
