diff options
| -rw-r--r-- | compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs index e068e607902..7f1f3c3c802 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/inspect_obligations.rs @@ -4,6 +4,7 @@ use rustc_infer::traits::{self, ObligationCause, PredicateObligations}; use rustc_middle::traits::solve::GoalSource; use rustc_middle::ty::{self, Ty, TypeVisitableExt}; use rustc_span::Span; +use rustc_trait_selection::solve::Certainty; use rustc_trait_selection::solve::inspect::{ InspectConfig, InspectGoal, ProofTreeInferCtxtExt, ProofTreeVisitor, }; @@ -117,6 +118,20 @@ impl<'a, 'tcx> ProofTreeVisitor<'tcx> for NestedObligationsForSelfTy<'a, 'tcx> { } fn visit_goal(&mut self, inspect_goal: &InspectGoal<'_, 'tcx>) { + // No need to walk into goal subtrees that certainly hold, since they + // wouldn't then be stalled on an infer var. + // FIXME: We also walk into normalizes-to goals since their certainty + // is forced to `Certainty::Yes` since they pass down ambiguous subgoals + // to their parent. + if inspect_goal.result() == Ok(Certainty::Yes) + && !matches!( + inspect_goal.goal().predicate.kind().skip_binder(), + ty::PredicateKind::NormalizesTo(_) + ) + { + return; + } + let tcx = self.fcx.tcx; let goal = inspect_goal.goal(); if self.fcx.predicate_has_self_ty(goal.predicate, self.self_ty) |