bug#47461: 27.2; Cannot delete windows due to some trouble with markers

bug#47461: 27.2; Cannot delete windows due to some trouble with markers

[Eli Zaretskii]

I don't have a reproducer, since I don't know yet why would some
marker in some buffer become invalid.

However, given that this does happen for some reason, I am unable to
delete windows via "C-x 1" and "C-x 0", due to this part of
delete-window:

  (interactive)
  (when switch-to-buffer-preserve-window-point
    (window--before-delete-windows))  <<<<<<<<<<<<<<<<<<<<<<

(Recall that switch-to-buffer-preserve-window-point is nowadays t by
default.)

What happens is that window--before-delete-windows works with markers,
and if that signals an error, the whole command is aborted.  All you
get is this unhelpful error message:

  Marker does not point anywhere

Fortunately, mouse-delete-window and mouse-delete-other-windows don't
have the code shown above, so I was able to work around the problem by
using those mouse commands.  Another workaround is to temporarily
reset switch-to-buffer-preserve-window-point, but that is only
apparent if you read the code and realize or know that
window--before-delete-windows is the one that signals the error.

Should we perhaps run this with demoted errors in the interactive
case, so that users aren't locked when something like that happens?

(I will try to figure out which marker becomes invalid and why.)

In GNU Emacs 27.2 (build 2, i686-pc-mingw32)
 of 2021-03-25 built on HOME-C4E4A596F7
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
System Description: Microsoft Windows XP Service Pack 3 (v5.1.0.2600)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

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bug#47461: 27.2; Cannot delete windows due to some trouble with markers

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> I don't have a reproducer, since I don't know yet why would some
> marker in some buffer become invalid.
>
> However, given that this does happen for some reason, I am unable to
> delete windows via "C-x 1" and "C-x 0", due to this part of
> delete-window:
>
>   (interactive)
>   (when switch-to-buffer-preserve-window-point
>     (window--before-delete-windows))  <<<<<<<<<<<<<<<<<<<<<<

This code no longer seems to exist, so perhaps this is no longer an
issue?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#47461: 27.2; Cannot delete windows due to some trouble with markers

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

>> I don't have a reproducer, since I don't know yet why would some
>> marker in some buffer become invalid.
>>
>> However, given that this does happen for some reason, I am unable to
>> delete windows via "C-x 1" and "C-x 0", due to this part of
>> delete-window:
>>
>>   (interactive)
>>   (when switch-to-buffer-preserve-window-point
>>     (window--before-delete-windows))  <<<<<<<<<<<<<<<<<<<<<<
>
> This code no longer seems to exist, so perhaps this is no longer an
> issue?

This was a month ago -- Eli, are you still seeing these issues?

bug#47461: 27.2; Cannot delete windows due to some trouble with markers

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 47461@debbugs.gnu.org
> Date: Wed, 27 Jul 2022 12:00:11 +0200
> 
> Lars Ingebrigtsen <larsi@gnus.org> writes:
> 
> >> I don't have a reproducer, since I don't know yet why would some
> >> marker in some buffer become invalid.
> >>
> >> However, given that this does happen for some reason, I am unable to
> >> delete windows via "C-x 1" and "C-x 0", due to this part of
> >> delete-window:
> >>
> >>   (interactive)
> >>   (when switch-to-buffer-preserve-window-point
> >>     (window--before-delete-windows))  <<<<<<<<<<<<<<<<<<<<<<
> >
> > This code no longer seems to exist, so perhaps this is no longer an
> > issue?
> 
> This was a month ago -- Eli, are you still seeing these issues?

No.  But it's very rare, so I don't know.

However, if the code in question no longer exists, I guess it's okay
to close.  Done.

Thanks.