Rollup merge of rust-lang#99110 - audunhalland:match_has_guard_from_candidate, r=pnkfelix

Determine match_has_guard from candidates instead of looking up thir table again

Currently looking through mir build of matches because of interest in deref patterns. Finding some micro-optimizable things.

Author: Dylan-DPC

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -170,7 +170,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
         let mut arm_candidates = self.create_match_candidates(scrutinee_place.clone(), &arms);
 
-        let match_has_guard = arms.iter().copied().any(|arm| self.thir[arm].guard.is_some());
+        let match_has_guard = arm_candidates.iter().any(|(_, candidate)| candidate.has_guard);
         let mut candidates =
             arm_candidates.iter_mut().map(|(_, candidate)| candidate).collect::<Vec<_>>();