This is a regression.

 while (!dir_iterator.next().isEmpty())

segfaults with 6.8 but not with 6.5 on macOS.

Qt docs on `next()`

If hasNext() returns false, this function does nothing, and returns an empty QString.

This

      while (fIt.hasNext())
        {
            DEBG << fIt.next();

works on 6.8 and 6.5.

The source seems to be QDirListing. See here for some backtraces and some more info.