message: we don't need zero-sized freeze-sensitive visiting
diff: @@ -58,6 +58,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
  .map(|(size, _)| size)
  .unwrap_or_else(|| place.layout.size)
  );
  + assert!(size.bytes() > 0);
  // Store how far we proceeded into the place so far. Everything to the left of
  // this offset has already been handled, in the sense that the frozen parts
  // have had `action` called on them.
  