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// 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.
#![feature(unboxed_closures)]
// 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);
}
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