From e32011209d185a12575c90929c13211936a3f421 Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Thu, 20 Jul 2023 20:02:56 +0000 Subject: [PATCH] Get rid of subst-relate incompleteness in new solver --- .../src/solve/alias_relate.rs | 21 +++++++++++-------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/compiler/rustc_trait_selection/src/solve/alias_relate.rs b/compiler/rustc_trait_selection/src/solve/alias_relate.rs index 73362d823065a..3c7f91e6ca9be 100644 --- a/compiler/rustc_trait_selection/src/solve/alias_relate.rs +++ b/compiler/rustc_trait_selection/src/solve/alias_relate.rs @@ -66,24 +66,27 @@ impl<'tcx> EvalCtxt<'_, 'tcx> { Invert::Yes, )); // Relate via args - let subst_relate_response = self - .assemble_subst_relate_candidate(param_env, alias_lhs, alias_rhs, direction); - candidates.extend(subst_relate_response); + candidates.extend( + self.assemble_subst_relate_candidate( + param_env, alias_lhs, alias_rhs, direction, + ), + ); debug!(?candidates); if let Some(merged) = self.try_merge_responses(&candidates) { Ok(merged) } else { - // When relating two aliases and we have ambiguity, we prefer - // relating the generic arguments of the aliases over normalizing - // them. This is necessary for inference during typeck. + // When relating two aliases and we have ambiguity, if both + // aliases can be normalized to something, we prefer + // "bidirectionally normalizing" both of them within the same + // candidate. + // + // See . // // As this is incomplete, we must not do so during coherence. match self.solver_mode() { SolverMode::Normal => { - if let Ok(subst_relate_response) = subst_relate_response { - Ok(subst_relate_response) - } else if let Ok(bidirectional_normalizes_to_response) = self + if let Ok(bidirectional_normalizes_to_response) = self .assemble_bidirectional_normalizes_to_candidate( param_env, lhs, rhs, direction, )