diff --git a/compiler/rustc_mir_build/src/build/matches/simplify.rs b/compiler/rustc_mir_build/src/build/matches/simplify.rs index a7f6f4873e3..c2e44a06321 100644 --- a/compiler/rustc_mir_build/src/build/matches/simplify.rs +++ b/compiler/rustc_mir_build/src/build/matches/simplify.rs @@ -62,19 +62,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { let mut existing_bindings = mem::take(&mut candidate.bindings); let mut new_bindings = Vec::new(); loop { - let match_pairs = mem::take(&mut candidate.match_pairs); - - if let [MatchPair { pattern: Pat { kind: PatKind::Or { pats }, .. }, place }] = - &*match_pairs - { - existing_bindings.extend_from_slice(&new_bindings); - mem::swap(&mut candidate.bindings, &mut existing_bindings); - candidate.subcandidates = self.create_or_subcandidates(candidate, place, pats); - return true; - } - let mut changed = false; - for match_pair in match_pairs { + for match_pair in mem::take(&mut candidate.match_pairs) { match self.simplify_match_pair(match_pair, candidate) { Ok(()) => { changed = true; @@ -84,6 +73,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { } } } + // Avoid issue #69971: the binding order should be right to left if there are more // bindings after `@` to please the borrow checker // Ex @@ -102,18 +92,32 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { candidate.bindings.clear(); if !changed { - existing_bindings.extend_from_slice(&new_bindings); - mem::swap(&mut candidate.bindings, &mut existing_bindings); - // Move or-patterns to the end, because they can result in us - // creating additional candidates, so we want to test them as - // late as possible. - candidate - .match_pairs - .sort_by_key(|pair| matches!(pair.pattern.kind, PatKind::Or { .. })); - debug!(simplified = ?candidate, "simplify_candidate"); - return false; // if we were not able to simplify any, done. + // If we were not able to simplify anymore, done. + break; } } + + existing_bindings.extend_from_slice(&new_bindings); + mem::swap(&mut candidate.bindings, &mut existing_bindings); + + let did_expand_or = + if let [MatchPair { pattern: Pat { kind: PatKind::Or { pats }, .. }, place }] = + &*candidate.match_pairs + { + candidate.subcandidates = self.create_or_subcandidates(candidate, place, pats); + candidate.match_pairs.clear(); + true + } else { + false + }; + + // Move or-patterns to the end, because they can result in us + // creating additional candidates, so we want to test them as + // late as possible. + candidate.match_pairs.sort_by_key(|pair| matches!(pair.pattern.kind, PatKind::Or { .. })); + debug!(simplified = ?candidate, "simplify_candidate"); + + did_expand_or } /// Given `candidate` that has a single or-pattern for its match-pairs,