Address review comments

clippy_utils/src/mir/possible_borrower.rs

@@ -11,7 +11,6 @@ use rustc_mir_dataflow::{
  fmt::DebugWithContext, impls::MaybeStorageLive, lattice::JoinSemiLattice, Analysis, AnalysisDomain,
  CallReturnPlaces, ResultsCursor,
 };
-use std::collections::VecDeque;
 use std::ops::ControlFlow;
 
 /// Collects the possible borrowers of each local.
@@ -216,6 +215,8 @@ pub struct PossibleBorrowerMap<'b, 'tcx> {
  body: &'b mir::Body<'tcx>,
  possible_borrower: ResultsCursor<'b, 'tcx, PossibleBorrowerAnalysis<'b, 'tcx>>,
  maybe_live: ResultsCursor<'b, 'tcx, MaybeStorageLive>,
+ pushed: BitSet<Local>,
+ stack: Vec<Local>,
 }
 
 impl<'b, 'tcx> PossibleBorrowerMap<'b, 'tcx> {
@@ -239,6 +240,8 @@ impl<'b, 'tcx> PossibleBorrowerMap<'b, 'tcx> {
  body: mir,
  possible_borrower,
  maybe_live,
+ pushed: BitSet::new_empty(mir.local_decls.len()),
+ stack: Vec::with_capacity(mir.local_decls.len()),
  }
  }
 
@@ -269,29 +272,29 @@ impl<'b, 'tcx> PossibleBorrowerMap<'b, 'tcx> {
  let possible_borrower = &self.possible_borrower.get().map;
  let maybe_live = &self.maybe_live;
 
- let mut queued = BitSet::new_empty(self.body.local_decls.len());
- let mut deque = VecDeque::with_capacity(self.body.local_decls.len());
+ self.pushed.clear();
+ self.stack.clear();
 
  if let Some(borrowers) = possible_borrower.get(&borrowed) {
  for b in borrowers.iter() {
- if queued.insert(b) {
- deque.push_back(b);
+ if self.pushed.insert(b) {
+ self.stack.push(b);
  }
  }
  } else {
  // Nothing borrows `borrowed` at `at`.
  return true;
  }
 
- while let Some(borrower) = deque.pop_front() {
+ while let Some(borrower) = self.stack.pop() {
  if maybe_live.contains(borrower) && !borrowers.contains(&borrower) {
  return false;
  }
 
  if let Some(borrowers) = possible_borrower.get(&borrower) {
  for b in borrowers.iter() {
- if queued.insert(b) {
- deque.push_back(b);
+ if self.pushed.insert(b) {
+ self.stack.push(b);
  }
  }
  }