bug#60467: 30.0.50; primitive-undo: Changes to be undone by function different from announced

[Eli Zaretskii]

[Please don't change the Subject when you reopen a bug.]

> Date: Thu, 22 Jun 2023 21:28:44 +0200
> From:  Frédéric Giquel via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Hi all,
> 
> I'm reopening this bug because the fix has introduced a new problem.
> 
> This can be highlighted with the following procedure (verified with
> Emacs 29.0.92) :
> 1. Open a file: emacs -Q <file>
> 2. Move point to a line you can comment
> 3. M-x comment-line
> 4. M-x undo
> 5. Check buffer modification status in modeline or use (buffer-
> modified-p)
> 
> Without the patched version of combine-change-calls-1, the buffer
> status is "not modified since last save". Same result if you use
> another command, for example kill-line,  at step 2.
> With new version of combine-change-calls-1, the buffer is seen as
> modified.
> 
> I'm not sure but I imagine it has something to do with the lack of
> timestamp in buffer-undo-list created by combine-change-calls-1.

Stefan, can you please look into this?