bug#46908: 28.0.50; Dozens of spurious markers in buffer-undo-list

[Eli Zaretskii]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Date: Sat, 06 Mar 2021 01:51:00 +0100
> Cc: 46908@debbugs.gnu.org, Yuan Fu <casouri@gmail.com>
> 
> My question is what amount of that is pathological.  A lot of code
> creates markers "on the fly", a lot, e.g. jit-lock or yank (push-mark)
> or display-buffer.  When undo is performed before gc is run, they end in
> buffer-undo-list.
> 
> Does making a marker point to nil with `set-marker' then make it
> suitable for garbage collection?  I guess not.

GC compacts the buffer's undo-list, and that is supposed to remove
those entries.  Doesn't it?