message: make execution with full MIR work: need to whitelist Arc drop impl and whatever it calls
diff: @@ -42,6 +42,7 @@ impl<'a, 'tcx, M: Machine<'tcx>> EvalContext<'a, 'tcx, M> {
  // HACK: Determine if this method is whitelisted and hence we do not perform any validation.
  // We currently insta-UB on anything passing around uninitialized memory, so we have to whitelist
  // the places that are allowed to do that.
  + // The second group is stuff libstd does that is forbidden even under relaxed validation.
  {
  // The regexp we use for filtering
  use regex::Regex;
  @@ -52,7 +53,12 @@ std::mem::forget::|\
  <std::heap::Heap as std::heap::Alloc>::|\
  <std::mem::ManuallyDrop<T>><.*>::new$|\
  <std::mem::ManuallyDrop<T> as std::ops::DerefMut><.*>::deref_mut$|\
  -std::ptr::read::\
  + std::ptr::read::|\
  + \
  + <std::sync::Arc<T>><.*>::inner$|\
  + <std::sync::Arc<T>><.*>::drop_slow$|\
  + std::heap::Layout::for_value::|\
  + std::mem::(size|align)_of_val::\
  )").unwrap();
  }
  // Now test
  