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

[Michael Heerdegen]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> I cannot confirm that, no.  I can reproduce the issue in a newly built
> Emacs 27 as well as in the 27 that comes with Debian.  "It" again being
> `count-markers-in-buffer-undo-list'.

The issue disappears (marker count stays constantly less than 3) if I
comment out these two expressions in `push-mark':

  (add-to-history 'mark-ring (copy-marker (mark-marker)) mark-ring-max t)

  (add-to-history
    'global-mark-ring (copy-marker (mark-marker)) global-mark-ring-max t)

I think we really have a problem here: when those newly created markers
are thrown out of the rings, they are not invalidated, and are also
still referenced by buffer-undo-list, so they will live forever, AFAIU.

Michael.