[rustc.git] / src / test / ui / higher-rank-trait-bounds / hrtb-fn-like-trait.rs

// run-pass
// A basic test of using a higher-ranked trait bound.


trait FnLike<A,R> {
    fn call(&self, arg: A) -> R;
}

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>(f: F)
    where F : for<'a> FnLike<&'a isize, &'a isize>
{
    let x = 3;
    let y = f.call(&x);
    assert_eq!(3, *y);
}

fn main() {
    call_repeatedly(Identity);
}
Commit	Line	Data
b7449926	1	// run-pass
1a4d82fc JJ	2	// A basic test of using a higher-ranked trait bound.
1a4d82fc JJ	3
c34b1796	4
1a4d82fc JJ	5	trait FnLike<A,R> {
	6	fn call(&self, arg: A) -> R;
	7	}
	8
	9	struct Identity;
	10
	11	impl<'a, T> FnLike<&'a T, &'a T> for Identity {
	12	fn call(&self, arg: &'a T) -> &'a T {
	13	arg
	14	}
	15	}
	16
	17	fn call_repeatedly<F>(f: F)
c34b1796	18	where F : for<'a> FnLike<&'a isize, &'a isize>
1a4d82fc JJ	19	{
	20	let x = 3;
	21	let y = f.call(&x);
	22	assert_eq!(3, *y);
	23	}
	24
	25	fn main() {
	26	call_repeatedly(Identity);
	27	}