bug#33341: closed (27.0.50; Undo log merging and change groups)

[GNU bug Tracking System]

Your message dated Fri, 27 Nov 2020 18:43:09 +0100
with message-id <87pn3ybsr6.fsf@web.de>
and subject line Re: bug#33341: 27.0.50; Undo log merging and change groups
has caused the debbugs.gnu.org bug report #33341,
regarding 27.0.50; Undo log merging and change groups
to be marked as done.

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33341: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=33341
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> --- Begin Message ---
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>
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> Subject: 
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> 27.0.50; Undo log merging and change groups
>
>
>
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> Date: 
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> Sun, 11 Nov 2018 08:50:43 +0100
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)
>
>
>
>
> Hello,
>
> I have been playing with the undo change group functions.  I found
> `cancel-change-group' does not always work as expected.  For example, if
> you define
>
> (defun my-test-change-groups ()
>   (interactive)
>   (insert "0\n")
>   (let ((g (prepare-change-group)))
>     (activate-change-group g)
>     (insert "b\n")
>     (insert "c\n")
>     (cancel-change-group g)))
>
> and call that command in some random buffer, the final
> `cancel-change-group' has no effect (i.e. nothing is reverted).  In
> other, similar examples, `cancel-change-group' seems to revert more than
> it should.
>
> To cite (CC'd) Stefan's remark in emacs-help, "the undo entries for
> (insert "0\n"), (insert "b\n"), and (insert "c\n") are merged into a
> single entry in the undo log (as a form of optimization).  The
> change-group code should prevent such a merge, e.g. by adding some dummy
> undo element which will work like a "fence"".
>
>
> Thanks,
>
> Michael.
>
>
>
>
> In GNU Emacs 27.0.50 (build 8, x86_64-pc-linux-gnu, GTK+ Version 3.24.1)
>  of 2018-11-11 built on drachen
> Repository revision: c1095b03a933d55fe1cd357881f1ca6e16e06362
> Repository branch: master
> Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
> System Description: Debian GNU/Linux buster/sid
>
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#33341: 27.0.50; Undo log merging and change groups
>
>
>
>
> Date: 
>
> Fri, 27 Nov 2020 18:43:09 +0100
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux)
>
>
>
>
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
> > diff --git a/lisp/subr.el b/lisp/subr.el
> > index e009dcc2b9..1cf3a49fe4 100644
> > --- a/lisp/subr.el
> > +++ b/lisp/subr.el
> > [...]
> > +     (undo-boundary)))))
>
> Confirmed that it's fixed with that commit.
>
> Thanks!
>
> Michael.
>
>
> --- End Message ---