bug#31492: 26.1; query-replace-regexp undo fails in regexps w/o printable chars

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Date: Sun, 20 May 2018 21:06:21 +0900 (JST)
> cc: Tino Calancha <tino.calancha@gmail.com>, 31492@debbugs.gnu.org
> 
> >> If the problem arise from using markers istead of integers, then how
> >> about we just use integers?
> >
> > Does this work with '^' and 'C-e', if they change text before a match
> > that was already replaced and recorded?
> I don't understand.  Do you have a recipe?

Not a recipe, an idea: I'm bothered by the possibility of the saved
positions becoming outdated if something changes text before the saved
positions.  Markers would move with the text, but positions won't.

The question is: is such a situation possible?