bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Alfred M. Szmidt]

When in vc-dired, with a relativley long list of files, and one issues
'g' (revert-buffer) the buffer scrolls downwards until the pointer
hits the bottem and then recenters.


In GNU Emacs 26.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars)
 of 2017-07-14 built on carbonium
Repository revision: 3bdf5b21493828bb0e8c0c6b4559a89aade0357f
Windowing system distributor 'The X.Org Foundation', version 11.0.11604000
System Description:	Debian GNU/Linux 8.8 (jessie)

Recent messages:
Added to /home/ams/GNU/savannah.xmail
Computing summary lines...done
Added to /home/ams/RMAIL.inbox
Mark set
vc-dir-refresh: Another update process is in progress, cannot run two at a time [27 times]
Type "q" in help window to restore its previous buffer.

Quit [2 times]
delete-forward-char: End of buffer
Making completion list... [2 times]

Configured using:
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Configured features:
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TOOLKIT_SCROLL_BARS LUCID X11

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bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Eli Zaretskii]

> From: ams@gnu.org (Alfred M. Szmidt)
> Date: Sat, 02 Sep 2017 14:23:27 -0400
> 
> 
> When in vc-dired, with a relativley long list of files, and one issues
> 'g' (revert-buffer) the buffer scrolls downwards until the pointer
> hits the bottem and then recenters.

I seem to be unable to reproduce this.  Does this happen for you in
"emacs -Q"?  If it does, could you show a complete recipe, start with
"emacs -Q"?

Also how long is "relatively long"?  Is longer than the window shows
good enough, or are there other conditions to be satisfied for tyhis
to show up?

Thanks.

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Alfred M. Szmidt]

   > When in vc-dired, with a relativley long list of files, and one issues
   > 'g' (revert-buffer) the buffer scrolls downwards until the pointer
   > hits the bottem and then recenters.

   I seem to be unable to reproduce this.  Does this happen for you in
   "emacs -Q"?  If it does, could you show a complete recipe, start with
   "emacs -Q"?

Yeah, occurs in -Q as well, this is what I tried:

  emacs -Q
  C-x v ~/
  C-u C-u C-u C-v
  g g g g ...

That will move the buffer one line.  The vc-dired buffer in question
has around 300 lines, the window can show 100x26.

   Also how long is "relatively long"?  Is longer than the window shows
   good enough, or are there other conditions to be satisfied for tyhis
   to show up?

If the buffer is shorter than the screen, then g (revert-buffer)
behaves as if previous-line was called.

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Eli Zaretskii]

> From: ams@gnu.org (Alfred M. Szmidt)
> CC: 28332@debbugs.gnu.org
> Date: Sat, 02 Sep 2017 16:03:08 -0400
> 
>   emacs -Q
>   C-x v ~/
>   C-u C-u C-u C-v
>   g g g g ...
> 
> That will move the buffer one line.  The vc-dired buffer in question
> has around 300 lines, the window can show 100x26.
> 
>    Also how long is "relatively long"?  Is longer than the window shows
>    good enough, or are there other conditions to be satisfied for tyhis
>    to show up?
> 
> If the buffer is shorter than the screen, then g (revert-buffer)
> behaves as if previous-line was called.

Right, I see this as well, thanks.  It is not specific to SVN, though:
I see the same in a vc-dir buffer showing a Git or Bazaar repository.

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Alfred M. Szmidt]

   >   emacs -Q
   >   C-x v ~/
   >   C-u C-u C-u C-v
   >   g g g g ...
   > 
   > That will move the buffer one line.  The vc-dired buffer in question
   > has around 300 lines, the window can show 100x26.
   > 
   >    Also how long is "relatively long"?  Is longer than the window shows
   >    good enough, or are there other conditions to be satisfied for tyhis
   >    to show up?
   > 
   > If the buffer is shorter than the screen, then g (revert-buffer)
   > behaves as if previous-line was called.

   Right, I see this as well, thanks.  It is not specific to SVN, though:
   I see the same in a vc-dir buffer showing a Git or Bazaar repository.

Yeah, that was a typo on my side should have been vc-dir.  I started
digging in the code, and ended up in vc-dir-update, but couldn't
really follow the code in there.

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> That will move the buffer one line.  The vc-dired buffer in question
>> has around 300 lines, the window can show 100x26.
>> 
>>    Also how long is "relatively long"?  Is longer than the window shows
>>    good enough, or are there other conditions to be satisfied for tyhis
>>    to show up?
>> 
>> If the buffer is shorter than the screen, then g (revert-buffer)
>> behaves as if previous-line was called.
>
> Right, I see this as well, thanks.  It is not specific to SVN, though:
> I see the same in a vc-dir buffer showing a Git or Bazaar repository.

I'm not seeing this behaviour (in Emacs 26.1 or 28) -- `g' recenters the
window, though.  Are there any additional steps needed (than having a
long list of files in vc-dir and a shorter window than that)?

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

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: ams@gnu.org (Alfred M. Szmidt),  28332@debbugs.gnu.org
> Date: Fri, 03 Sep 2021 10:02:45 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> That will move the buffer one line.  The vc-dired buffer in question
> >> If the buffer is shorter than the screen, then g (revert-buffer)
> >> behaves as if previous-line was called.
> >
> > Right, I see this as well, thanks.  It is not specific to SVN, though:
> > I see the same in a vc-dir buffer showing a Git or Bazaar repository.
> 
> I'm not seeing this behaviour (in Emacs 26.1 or 28) -- `g' recenters the
> window, though.  Are there any additional steps needed (than having a
> long list of files in vc-dir and a shorter window than that)?

The recentering _is_ the problem, AFAIU: why does 'g' do that?

bug#28332: 26.0.50; vc-svn: calling revert-buffer multiple causes scrolling of buffer

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> I'm not seeing this behaviour (in Emacs 26.1 or 28) -- `g' recenters the
>> window, though.  Are there any additional steps needed (than having a
>> long list of files in vc-dir and a shorter window than that)?
>
> The recentering _is_ the problem, AFAIU: why does 'g' do that?

Oh, OK -- I was just wondering if I was seeing something else than you
were.

I don't mind the recentering, really, but it is somewhat unusual
behaviour for a `g'-like command.  Perhaps Dmitry has some comments;
added to the CCs.

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