GNU bug report logs - #45581
28.0.50; C-M-v in xref buffers shows a different buffer when scrolling

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Daniel Martín <mardani29 <at> yahoo.es>
To: bug-gnu-emacs <at> gnu.org
Subject: 28.0.50; C-M-v in xref buffers shows a different buffer when scrolling
Date: Thu, 31 Dec 2020 23:51:38 +0100

Steps to reproduce the problem:

1. emacs -Q
2. Open any file with source code (for example, xdisp.c).
3. Place the point in any symbol (for example, redisplay_internal).
4. Press M-? (`xref-find-references').
5. In the *xref* buffer, press n (`xref-next-line').
6. Press C-h m (`describe-mode').
7. Press C-M-v to scroll the help window.

Expected results:

The mode description window scrolls as usual.

Actual results:

The buffer with the file that contains the selected xref item replaces
the *Help* buffer and is scrolled instead.

I can't reproduce the same behavior in *grep* buffers.

Message #8 received at 45581 <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Daniel Martín <mardani29 <at> yahoo.es>, 45581 <at> debbugs.gnu.org
Subject: Re: bug#45581: 28.0.50; C-M-v in xref buffers shows a different
 buffer when scrolling
Date: Sat, 2 Jan 2021 00:43:36 +0200

Hi!

On 01.01.2021 00:51, Daniel Martín via Bug reports for GNU Emacs, the 
Swiss army knife of text editors wrote:
> 
> Steps to reproduce the problem:
> 
> 1. emacs -Q
> 2. Open any file with source code (for example, xdisp.c).
> 3. Place the point in any symbol (for example, redisplay_internal).
> 4. Press M-? (`xref-find-references').
> 5. In the *xref* buffer, press n (`xref-next-line').
> 6. Press C-h m (`describe-mode').
> 7. Press C-M-v to scroll the help window.
> 
> Expected results:
> 
> The mode description window scrolls as usual.
> 
> Actual results:
> 
> The buffer with the file that contains the selected xref item replaces
> the *Help* buffer and is scrolled instead.
> 
> I can't reproduce the same behavior in *grep* buffers.

Thanks for the report.

Xref buffers have been doing this since bug#19466, as requested by 
Martin (see https://debbugs.gnu.org/cgi/bugreport.cgi?bug=19466#56).

Perhaps Martin or others will chime in, but otherwise you seem to be 
making a good case for not doing this anymore.

Message #11 received at 45581 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Dmitry Gutov <dgutov <at> yandex.ru>, Daniel Martín
 <mardani29 <at> yahoo.es>, 45581 <at> debbugs.gnu.org
Subject: Re: bug#45581: 28.0.50; C-M-v in xref buffers shows a different
 buffer when scrolling
Date: Sat, 2 Jan 2021 09:25:38 +0100

> Xref buffers have been doing this since bug#19466, as requested by
> Martin (see https://debbugs.gnu.org/cgi/bugreport.cgi?bug=19466#56).
>
> Perhaps Martin or others will chime in, but otherwise you seem to be
> making a good case for not doing this anymore.

Probably.  'cvs-temp-buffer' has a similar note:

      ;; FIXME: this doesn't do the right thing if the user later on
      ;; does a `find-file-other-window' and `scroll-other-window'
      (setq-local other-window-scroll-buffer buf))

I don't use C-M-v so I can't tell whether 'other-window-scroll-buffer'
was ever useful in the first place for *xref*.

martin

Message #16 received at 45581-done <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: martin rudalics <rudalics <at> gmx.at>, Daniel Martín
 <mardani29 <at> yahoo.es>, 45581-done <at> debbugs.gnu.org
Subject: Re: bug#45581: 28.0.50; C-M-v in xref buffers shows a different
 buffer when scrolling
Date: Sat, 2 Jan 2021 20:58:24 +0200

Version: 28.1

On 02.01.2021 10:25, martin rudalics wrote:
> Probably.  'cvs-temp-buffer' has a similar note:
> 
>        ;; FIXME: this doesn't do the right thing if the user later on
>        ;; does a `find-file-other-window' and `scroll-other-window'
>        (setq-local other-window-scroll-buffer buf))
> 
> I don't use C-M-v so I can't tell whether 'other-window-scroll-buffer'
> was ever useful in the first place for *xref*.

Great, so we can remove it (pushed as 6b10ce867f).

As a result, C-M-v doesn't always scroll the "target location" window 
anymore (at least, not when there are at least 3 windows on the frame).

I wonder if we can/should do something about it. Other standard commands 
don't seem to worry about that, though.

Message #19 received at 45581-done <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Dmitry Gutov <dgutov <at> yandex.ru>, Daniel Martín
 <mardani29 <at> yahoo.es>, 45581-done <at> debbugs.gnu.org
Subject: Re: bug#45581: 28.0.50; C-M-v in xref buffers shows a different
 buffer when scrolling
Date: Sun, 3 Jan 2021 09:40:13 +0100

> As a result, C-M-v doesn't always scroll the "target location" window anymore (at least, not when there are at least 3 windows on the frame).
>
> I wonder if we can/should do something about it. Other standard commands don't seem to worry about that, though.

I doubt that anybody cares.  My suggestion back then was just bad.
'other-window-scroll-buffer' is an ill-advised concept which can fly
only if the buffer where it is set locally is small (so a user will not
wonder about what that buffer has been conceived for and, for example,
ask questions about its modes or keymaps) is displayed for a short time
only and the visibility of the buffer it refers to is absolutely crucial
for the current workflow.  Neither of these conditions is given in the
present context and I doubt that they are given in any of the other
occurrences of that variable.

martin

Message #22 received at 45581-done <at> debbugs.gnu.org (full text, mbox):

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: martin rudalics <rudalics <at> gmx.at>, Daniel Martín
 <mardani29 <at> yahoo.es>, 45581-done <at> debbugs.gnu.org
Subject: Re: bug#45581: 28.0.50; C-M-v in xref buffers shows a different
 buffer when scrolling
Date: Mon, 4 Jan 2021 02:22:19 +0200

On 03.01.2021 10:40, martin rudalics wrote:
> I doubt that anybody cares.  My suggestion back then was just bad.
> 'other-window-scroll-buffer' is an ill-advised concept which can fly
> only if the buffer where it is set locally is small (so a user will not
> wonder about what that buffer has been conceived for and, for example,
> ask questions about its modes or keymaps) is displayed for a short time
> only and the visibility of the buffer it refers to is absolutely crucial
> for the current workflow.  Neither of these conditions is given in the
> present context and I doubt that they are given in any of the other
> occurrences of that variable.

Thanks. So we'll keep it the way it is now.

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