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// compile-flags: -Znext-solver
// check-pass
trait Eq<'a, 'b, T> {}
trait Ambig {}
impl Ambig for () {}
impl<'a, T> Eq<'a, 'a, T> for () where T: Ambig {}
fn eq<'a, 'b, T>(t: T)
where
(): Eq<'a, 'b, T>,
{
}
fn test<'r>() {
let mut x = Default::default();
// When we evaluate `(): Eq<'r, 'r, ?0>` we uniquify the regions.
// That leads us to evaluate `(): Eq<'?0, '?1, ?0>`. The response of this
// will be ambiguous (because `?0: Ambig` is ambig) and also not an "identity"
// response, since the region constraints will contain `'?0 == '?1` (so
// `is_changed` will return true). Since it's both ambig and changed,
// fulfillment will both re-register the goal AND loop again. This hits the
// overflow limit. This should neither be considered overflow, nor ICE.
eq::<'r, 'r, _>(x);
x = ();
}
fn main() {}
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