Replace the loop with recursive calls for clarity

Author: Nadrieril

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

@@ -1212,35 +1212,38 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
  candidates: &mut [&mut Candidate<'_, 'tcx>],
  fake_borrows: &mut Option<FxIndexSet<Place<'tcx>>>,
  ) {
- // The candidates are sorted by priority. Check to see whether the
- // higher priority candidates (and hence at the front of the slice)
- // have satisfied all their match pairs.
- let fully_matched = candidates.iter().take_while(|c| c.match_pairs.is_empty()).count();
- debug!("match_candidates: {:?} candidates fully matched", fully_matched);
- let (matched_candidates, unmatched_candidates) = candidates.split_at_mut(fully_matched);
-
- for candidate in matched_candidates.iter_mut() {
- start_block = self.select_matched_candidate(candidate, start_block, fake_borrows);
- }
-
- // If there are no candidates that still need testing, we're
- // done. Since all matches are exhaustive, execution should
- // never reach this point.
- if unmatched_candidates.is_empty() {
- let source_info = self.source_info(span);
- self.cfg.goto(start_block, source_info, otherwise_block);
- return;
+ match candidates {
+ [] => {
+ // If there are no candidates that still need testing, we're done. Since all matches are
+ // exhaustive, execution should never reach this point.
+ let source_info = self.source_info(span);
+ self.cfg.goto(start_block, source_info, otherwise_block);
+ }
+ [first, remaining @ ..] if first.match_pairs.is_empty() => {
+ // The first candidate has satisfied all its match pairs; we link it up and continue
+ // with the remaining candidates.
+ start_block = self.select_matched_candidate(first, start_block, fake_borrows);
+ self.match_simplified_candidates(
+ span,
+ scrutinee_span,
+ start_block,
+ otherwise_block,
+ remaining,
+ fake_borrows,
+ )
+ }
+ candidates => {
+ // The first candidate has some unsatisfied match pairs; we proceed to do more tests.
+ self.test_candidates_with_or(
+ span,
+ scrutinee_span,
+ candidates,
+ start_block,
+ otherwise_block,
+ fake_borrows,
+ );
+ }
  }
-
- // Test for the remaining candidates.
- self.test_candidates_with_or(
- span,
- scrutinee_span,
- unmatched_candidates,
- start_block,
- otherwise_block,
- fake_borrows,
- );
  }
 
  /// Link up matched candidates.