[rustc.git] / src / test / ui / coherence / coherence-rfc447-constrained.rs

// run-pass
// check that trait matching can handle impls whose types are only
// constrained by a projection.

trait IsU32 {}
impl IsU32 for u32 {}

trait Mirror { type Image: ?Sized; }
impl<T: ?Sized> Mirror for T { type Image = T; }

trait Bar {}
impl<U: Mirror, V: Mirror<Image=L>, L: Mirror<Image=U>> Bar for V
    where U::Image: IsU32 {}

trait Foo { fn name() -> &'static str; }
impl Foo for u64 { fn name() -> &'static str { "u64" } }
impl<T: Bar> Foo for T { fn name() -> &'static str { "Bar" }}

fn main() {
    assert_eq!(<u64 as Foo>::name(), "u64");
    assert_eq!(<u32 as Foo>::name(), "Bar");
}
Commit	Line	Data
b7449926	1	// run-pass
92a42be0 SL	2	// check that trait matching can handle impls whose types are only
	3	// constrained by a projection.
	4
	5	trait IsU32 {}
	6	impl IsU32 for u32 {}
	7
	8	trait Mirror { type Image: ?Sized; }
	9	impl<T: ?Sized> Mirror for T { type Image = T; }
	10
	11	trait Bar {}
	12	impl<U: Mirror, V: Mirror<Image=L>, L: Mirror<Image=U>> Bar for V
	13	where U::Image: IsU32 {}
	14
	15	trait Foo { fn name() -> &'static str; }
	16	impl Foo for u64 { fn name() -> &'static str { "u64" } }
	17	impl<T: Bar> Foo for T { fn name() -> &'static str { "Bar" }}
	18
	19	fn main() {
	20	assert_eq!(<u64 as Foo>::name(), "u64");
	21	assert_eq!(<u32 as Foo>::name(), "Bar");
	22	}