Stop using Bubble in coherence and instead emulate it with an intercrate check

Author: oli-obk

compiler/rustc_infer/src/infer/opaque_types.rs

@@ -146,7 +146,11 @@ impl<'tcx> InferCtxt<'tcx> {
                         }
                     }
                     DefiningAnchor::Bubble => {}
-                    DefiningAnchor::Error => return None,
+                    DefiningAnchor::Error => {
+                        if !self.intercrate {
+                            return None;
+                        }
+                    }
                 };
                 if let ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }) = *b.kind() {
                     // We could accept this, but there are various ways to handle this situation, and we don't

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -26,7 +26,6 @@ use rustc_infer::traits::{util, TraitEngine, TraitEngineExt};
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::traits::solve::{CandidateSource, Certainty, Goal};
 use rustc_middle::traits::specialization_graph::OverlapMode;
-use rustc_middle::traits::DefiningAnchor;
 use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
 use rustc_middle::ty::visit::{TypeVisitable, TypeVisitableExt};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor};
@@ -190,7 +189,6 @@ fn overlap<'tcx>(
 
     let infcx = tcx
         .infer_ctxt()
-        .with_opaque_type_inference(DefiningAnchor::Bubble)
         .skip_leak_check(skip_leak_check.is_yes())
         .intercrate(true)
         .with_next_trait_solver(tcx.next_trait_solver_in_coherence())