diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/solve/delegate.rs | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/solve/delegate.rs b/compiler/rustc_trait_selection/src/solve/delegate.rs index 406acdb7d88..69a0c0809b5 100644 --- a/compiler/rustc_trait_selection/src/solve/delegate.rs +++ b/compiler/rustc_trait_selection/src/solve/delegate.rs @@ -125,6 +125,17 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate< Some(Certainty::Yes) } + ty::PredicateKind::Subtype(ty::SubtypePredicate { a, b, .. }) + | ty::PredicateKind::Coerce(ty::CoercePredicate { a, b }) => { + if self.shallow_resolve(a).is_ty_var() && self.shallow_resolve(b).is_ty_var() { + // FIXME: We also need to register a subtype relation between these vars + // when those are added, and if they aren't in the same sub root then + // we should mark this goal as `has_changed`. + Some(Certainty::AMBIGUOUS) + } else { + None + } + } _ => None, } } |