| //@ compile-flags: -Znext-solver |
| |
| trait Tr<'a> {} |
| |
| // Fulfillment in the new solver relies on an invariant to hold: Either |
| // `has_changed` is true, or computing a goal's certainty is idempotent. |
| // This isn't true for `ReError`, which we used to pass through in the |
| // canonicalizer even on input mode, which can cause a goal to go from |
| // ambig => pass, but we don't consider `has_changed` when the response |
| // only contains region constraints (since we usually uniquify regions). |
| // |
| // In this test: |
| // Implicit negative coherence tries to prove `W<?0>: Constrain<'?1>`, |
| // which will then match with the impl below. This constrains `'?1` to |
| // `ReError`, but still bails w/ ambiguity bc we can't prove `?0: Sized`. |
| // Then, when we recompute the goal `W<?0>: Constrain<'error>`, when |
| // collecting ambiguities and overflows, we end up assembling a default |
| // error candidate w/o ambiguity, which causes the goal to pass, and ICE. |
| impl<'a, A: ?Sized> Tr<'a> for W<A> {} |
| struct W<A: ?Sized>(A); |
| impl<'a, A: ?Sized> Tr<'a> for A where A: Constrain<'a> {} |
| //~^ ERROR conflicting implementations of trait `Tr<'_>` for type `W<_>` |
| |
| trait Constrain<'a> {} |
| impl<A: Sized> Constrain<'missing> for W<A> {} |
| //~^ ERROR use of undeclared lifetime name `'missing` |
| |
| fn main() {} |
