Subject: bug#79200: 31.0.50; Duplicated elements for '#<marker at' in buffer-undo-list

From: Eli Zaretskii <[email-masked]>
Date: Sun, 10 Aug 2025 07:45:14 +0300

> Cc: [email-masked], Alan Mackenzie <[email-masked]>,
>  Stefan Monnier <[email-masked]>,
>  Óscar Fuentes <[email-masked]>
> Date: Sat, 09 Aug 2025 18:30:37 +0000
> From:  Pip Cet via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <[email-masked]>
> 
> I think it may make more sense to find out who goes around creating
> markers and not cleaning up after them.

Isn't that format_mode_line_unwind_data, which you found, and the
missing detach_marker call?