| // `Opaque<'?1> := u8` is not a valid defining use here. |
| // |
| // Due to fundamental limitations of the member constraints algorithm, |
| // we require '?1 to be *equal* to some universal region. |
| // |
| // While '?1 is eventually inferred to be equal to 'x because of the constraint '?1: 'x, |
| // we don't consider them equal in the strict sense because they lack the bidirectional outlives |
| // constraints ['?1: 'x, 'x: '?1]. In NLL terms, they are not part of the same SCC. |
| // |
| // See #113971 for details. |
| |
| //@ revisions: basic member_constraints |
| #![feature(type_alias_impl_trait)] |
| |
| trait Captures<'a> {} |
| impl<T> Captures<'_> for T {} |
| |
| fn ensure_outlives<'a, X: 'a>(_: X) {} |
| fn relate<X>(_: X, _: X) {} |
| |
| type Opaque<'a> = impl Copy + Captures<'a>; |
| |
| #[define_opaque(Opaque)] |
| fn test<'x>(_: Opaque<'x>) { |
| let opaque = None::<Opaque<'_>>; // let's call this lifetime '?1 |
| |
| #[cfg(basic)] |
| let hidden = None::<u8>; |
| |
| #[cfg(member_constraints)] |
| let hidden = None::<&'x u8>; |
| |
| ensure_outlives::<'x>(opaque); // outlives constraint: '?1: 'x |
| relate(opaque, hidden); // defining use: Opaque<'?1> := u8 |
| //~^ ERROR expected generic lifetime parameter, found `'_` |
| } |
| |
| fn main() {} |
