GNU bug report logs - #47050
28.0.50; [PATCH] `next-error-find-buffer' does things in the wrong order

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

From: Nick Dokos <ndokos <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 28.0.50;
 [PATCH] `next-error-find-buffer' does things in the wrong  order
Date: Tue, 09 Mar 2021 14:37:49 -0500

The doc for `next-error' says:

<quote>
C-x ` normally uses the most recently started
compilation, grep, or occur buffer.  It can also operate on any
buffer with output from the M-x compile, M-x grep commands, or,
more generally, on any buffer in Compilation mode or with
Compilation Minor mode enabled, or any buffer in which
‘next-error-function’ is bound to an appropriate function.
To specify use of a particular buffer for error messages, type
C-x ` in that buffer.  You can also use the command
‘next-error-select-buffer’ to select the buffer to use for the subsequent
invocation of ‘next-error’.
</quote>

I interpreted that to mean that if I create e.g. two `grep' buffers and
rename them uniquely to `*grep*<2>' and `*grep<3>', then switching
to one or the other of them and calling `next-error' would use the hits
from that buffer. However it always uses the hits from the last-used grep
buffer and I have to change that explicitly, by calling
`next-error-select-buffer', instead of letting the current buffer
determine it.

The problem is caused by `next-error-find-buffer' which does things in
the (IMO) wrong order: it first checks for next-error-last-buffer and
then it checks for the current buffer.

Here is a patch to reverse the order:

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/simple.el b/lisp/simple.el
index f8050091d5..8796b612cc 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -298,15 +298,15 @@ next-error-find-buffer
    (funcall next-error-find-buffer-function avoid-current
                                             extra-test-inclusive
                                             extra-test-exclusive)
-   ;; 2. If next-error-last-buffer is an acceptable buffer, use that.
+   ;; 2. If the current buffer is acceptable, choose it.
+   (if (next-error-buffer-p (current-buffer) avoid-current
+			    extra-test-inclusive extra-test-exclusive)
+       (current-buffer))
+   ;; 3. If next-error-last-buffer is an acceptable buffer, use that.
    (if (and next-error-last-buffer
             (next-error-buffer-p next-error-last-buffer avoid-current
                                  extra-test-inclusive extra-test-exclusive))
        next-error-last-buffer)
-   ;; 3. If the current buffer is acceptable, choose it.
-   (if (next-error-buffer-p (current-buffer) avoid-current
-			    extra-test-inclusive extra-test-exclusive)
-       (current-buffer))
    ;; 4. Look for any acceptable buffer.
    (let ((buffers (buffer-list)))
      (while (and buffers
--8<---------------cut here---------------end--------------->8---


This arose in a question on the Emacs SE:

https://emacs.stackexchange.com/questions/63807/is-there-a-way-to-get-two-separate-next-error-lists-so-i-can-bind-them-to-two-di

---------------------------------------------------------------------------


In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.25, cairo version 1.16.0)
 of 2021-03-07 built on pierrot.dokosmarshall.org
Repository revision: 997142a4ddc98158cb71bdcef58df5a24f9a9a5c
Repository branch: comint-send-input-timeout
Windowing system distributor 'Fedora Project', version 11.0.12010000
System Description: Fedora 33 (Thirty Three)

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NOTIFY
INOTIFY PDUMPER PNG RSVG SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE
XIM XPM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
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  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
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  buffer-read-only: t
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Load-path shadows:
None found.

Features:
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backquote threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting cairo move-toolbar gtk x-toolkit
x multi-tty make-network-process emacs)

Memory information:
((conses 16 54100 9914)
 (symbols 48 6694 1)
 (strings 32 18784 1955)
 (string-bytes 1 617945)
 (vectors 16 13356)
 (vector-slots 8 176023 12810)
 (floats 8 21 50)
 (intervals 56 235 0)
 (buffers 992 12))

-- 
Nick



-- 
Nick

Message #8 received at 47050 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Nick Dokos <ndokos <at> gmail.com>
Cc: 47050 <at> debbugs.gnu.org
Subject: Re: bug#47050: 28.0.50; [PATCH] `next-error-find-buffer' does
 things in the wrong  order
Date: Thu, 11 Mar 2021 21:23:54 +0200

> The doc for `next-error' says:
> ...
> I interpreted that to mean that if I create e.g. two `grep' buffers and
> rename them uniquely to `*grep*<2>' and `*grep<3>', then switching
> to one or the other of them and calling `next-error' would use the hits
> from that buffer. However it always uses the hits from the last-used grep
> buffer and I have to change that explicitly, by calling
> `next-error-select-buffer', instead of letting the current buffer
> determine it.
>
> The problem is caused by `next-error-find-buffer' which does things in
> the (IMO) wrong order: it first checks for next-error-last-buffer and
> then it checks for the current buffer.

Please try the following use case:

0. emacs -Q
1. call `grep' (anywhere) that displays the *grep* buffer
2. switch to the the *grep* buffer
3. in the *grep* buffer call `occur' that displays the *Occur* buffer
   with matches from the *grep* buffer
4. switch to the *Occur* buffer
5. type C-x ` (`next-error') in the *Occur* buffer
6. type C-x ` again - it continues visiting hits from the *Occur* buffer

But with your patch the second C-x ` will stop visiting hits
from the *Occur* buffer.

Message #11 received at 47050 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Nick Dokos <ndokos <at> gmail.com>
Cc: 47050 <at> debbugs.gnu.org
Subject: Re: bug#47050: 28.0.50; [PATCH] `next-error-find-buffer' does
 things in the wrong  order
Date: Mon, 15 Mar 2021 19:07:12 +0200

> The doc for `next-error' says:
> ...
> I interpreted that to mean that if I create e.g. two `grep' buffers and
> rename them uniquely to `*grep*<2>' and `*grep<3>', then switching
> to one or the other of them and calling `next-error' would use the hits
> from that buffer. However it always uses the hits from the last-used grep
> buffer and I have to change that explicitly, by calling
> `next-error-select-buffer', instead of letting the current buffer
> determine it.

Please try to customize 'next-error-find-buffer-function' to this value:

  (const :tag "Current buffer if next-error capable and outside navigation"
         next-error-buffer-unnavigated-current)

It provides the behavior that you described.

Message #16 received at 47050 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Juri Linkov <juri <at> linkov.net>
Cc: Nick Dokos <ndokos <at> gmail.com>, 47050 <at> debbugs.gnu.org
Subject: Re: bug#47050: 28.0.50; [PATCH] `next-error-find-buffer' does
 things in the wrong  order
Date: Wed, 12 May 2021 21:01:57 +0200

Juri Linkov <juri <at> linkov.net> writes:

> Please try to customize 'next-error-find-buffer-function' to this value:
>
>   (const :tag "Current buffer if next-error capable and outside navigation"
>          next-error-buffer-unnavigated-current)
>
> It provides the behavior that you described.

More information was requested, but no response was given within a
month, so I'm closing this bug report.  If the problem still exists,
please respond to this email and we'll reopen the bug report.

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

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