//@ revisions: old next
//@[next] compile-flags: -Znext-solver
//@ check-pass

// The new trait solver does not return region constraints if the goal
// is still ambiguous. However, the `'!a = 'static` constraint from
// `(): LeakCheckFailure<'!a, V>`  is also returned via the canonical
// var values, causing this test to compile.

trait Ambig {}
impl Ambig for u32 {}
impl Ambig for u16 {}

trait Id<T> {}
impl Id<u32> for u32 {}
impl Id<u16> for u16 {}


trait LeakCheckFailure<'a, V: ?Sized> {}
impl<V: ?Sized + Ambig> LeakCheckFailure<'static, V> for () {}

trait Trait<U, V> {}
impl<V> Trait<u32, V> for () where for<'a> (): LeakCheckFailure<'a, V> {}
impl<V> Trait<u16, V> for () {}
fn impls_trait<T: Trait<U, V>, U: Id<V>, V>() {}
fn main() {
    impls_trait::<(), _, _>()
}