message: refactor away some 'else { None }'
diff: @@ -367,20 +367,14 @@ impl<'mir, 'tcx> Evaluator<'mir, 'tcx> {
  measureme::Profiler::new(out).expect("Couldn't create `measureme` profiler")
  });
  let rng = StdRng::seed_from_u64(config.seed.unwrap_or(0));
  - let stacked_borrows = if config.stacked_borrows {
  - Some(RefCell::new(stacked_borrows::GlobalStateInner::new(
  + let stacked_borrows = config.stacked_borrows.then(|| {
  + RefCell::new(stacked_borrows::GlobalStateInner::new(
  config.tracked_pointer_tags.clone(),
  config.tracked_call_ids.clone(),
  config.retag_fields,
  - )))
  - } else {
  - None
  - };
  - let data_race = if config.data_race_detector {
  - Some(data_race::GlobalState::new(config))
  - } else {
  - None
  - };
  + ))
  + });
  + let data_race = config.data_race_detector.then(|| data_race::GlobalState::new(config));
  Evaluator {
  stacked_borrows,
  data_race,
  @@ -691,32 +685,24 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'mir, 'tcx> {
  }
  let alloc = alloc.into_owned();
  - let stacks = if let Some(stacked_borrows) = &ecx.machine.stacked_borrows {
  - Some(Stacks::new_allocation(
  + let stacks = ecx.machine.stacked_borrows.as_ref().map(|stacked_borrows| {
  + Stacks::new_allocation(
  id,
  alloc.size(),
  stacked_borrows,
  kind,
  ecx.machine.current_span(),
  - ))
  - } else {
  - None
  - };
  - let race_alloc = if let Some(data_race) = &ecx.machine.data_race {
  - Some(data_race::AllocExtra::new_allocation(
  + )
  + });
  + let race_alloc = ecx.machine.data_race.as_ref().map(|data_race| {
  + data_race::AllocExtra::new_allocation(
  data_race,
  &ecx.machine.threads,
  alloc.size(),
  kind,
  - ))
  - } else {
  - None
  - };
  - let buffer_alloc = if ecx.machine.weak_memory {
  - Some(weak_memory::AllocExtra::new_allocation())
  - } else {
  - None
  - };
  + )
  + });
  + let buffer_alloc = ecx.machine.weak_memory.then(weak_memory::AllocExtra::new_allocation);
  let alloc: Allocation<Provenance, Self::AllocExtra> = alloc.adjust_from_tcx(
  &ecx.tcx,
  AllocExtra {
  