GNU bug report logs -
#54133
29.0.50; Buffer-menu-visit-tags-table disrupts non-tags buffers
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Reported by: Bob Rogers <rogers <at> rgrjr.com>
Date: Wed, 23 Feb 2022 21:38:01 UTC
Severity: normal
Found in version 29.0.50
Done: Eli Zaretskii <eliz <at> gnu.org>
Bug is archived. No further changes may be made.
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Your bug report
#54133: 29.0.50; Buffer-menu-visit-tags-table disrupts non-tags buffers
which was filed against the emacs package, has been closed.
The explanation is attached below, along with your original report.
If you require more details, please reply to 54133 <at> debbugs.gnu.org.
--
54133: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=54133
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems
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> From: Bob Rogers <rogers <at> rgrjr.com>
> Date: Thu, 24 Feb 2022 13:02:40 -0500
> CC: 54133 <at> debbugs.gnu.org
>
> Maybe we should have a more thorough implementation in
> etags-verify-tags-table, then. But that function's purpose is to do
> what we need here.
>
> That would require disentangling detection and initialization. Which
> shouldn't be all that hard; it just seemed like more work than necessary
> to scratch this particular itch.
>
> > In short, I thought checking the major mode was the better choice,
> > since the file was already present in a buffer.
>
> But what if the file is already in a buffer, but not under the right
> major-mode? E.g., what if the file was visited literally?
>
> Ah, so you mean that Buffer-menu-visit-tags-table is normally meant to
> introduce tags-table-mode in buffers not already there. I see now that
> is implied by "Visit the tags table ..." in the command documentation.
> In which case I withdraw my reservations.
Thanks, I installed the changes, and I'm marking this bug done.
> And maybe I'll have a look at cleaning up etags initialization when I
> get a chance . . .
TIA.
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In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo version 1.16.0)
of 2022-02-19 built on orion
Repository revision: 563bb08c5998f82e034a0aa1b48dce29fb9bc375
Repository branch: rgr-smtpmail-env-from
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
System Description: openSUSE Leap 15.3
Configured using:
'configure --with-dbus=no --with-gsettings=no --with-gif=ifavailable
--with-tiff=no --with-gnutls=yes --with-gconf=no'
Configured features:
ACL CAIRO FREETYPE GIF GLIB GMP GNUTLS HARFBUZZ JPEG LIBSELINUX LIBXML2
MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS
TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB
To reproduce:
In master ecaedf2117cb015ad4028e4d6fc7058608c98096:
1. "emacs -Q &"
2. Visit pretty much any random file that is NOT a tags file; for
this purpose, lisp/abbrev.el from the source tree will do nicely.
3. Type "C-x C-b" to get the "*Buffer List*" window to appear.
4. Type "C-x o" to move the to the buffer list, then move to the
abbrev.el line, and type "t" to invoke Buffer-menu-visit-tags-table on
it (which I seem to do accidentally more often than I care to admit).
This produces the error message:
user-error: File /scratch/rogers/emacs/lisp/abbrev.el is not a valid tags table
but the abbrev.el buffer is left in tags-table-mode, and any undo
information is thrown away.
The attached patch addresses the problem in a straightforward way by
making Buffer-menu-visit-tags-table prompt the user for buffers not
already in tags-table-mode.
The real problem is that visit-tags-table assumes that the user knows
what they're doing, and makes these irreversible changes before being
sure of having a valid tags table. That would be a harder thing to fix,
though -- and might not deal as well with my buffer-menu typos. ;-}
-- Bob Rogers
http://www.rgrjr.com/
[0001-Make-Buffer-menu-visit-tags-table-more-circumspect.patch (text/x-patch, inline)]
From 05d2d1855cddc8d5c310d718c07d91ae861b8436 Mon Sep 17 00:00:00 2001
From: Bob Rogers <rogers <at> rgrjr.com>
Date: Wed, 23 Feb 2022 16:23:17 -0500
Subject: [PATCH] Make Buffer-menu-visit-tags-table more circumspect
* lisp/buff-menu.el:
+ (Buffer-menu-visit-tags-table): Ask before visit-tags-table on a
buffer not already in tags-table-mode, lest it destroy state.
---
lisp/buff-menu.el | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/lisp/buff-menu.el b/lisp/buff-menu.el
index 50c2c155ca..0bed539008 100644
--- a/lisp/buff-menu.el
+++ b/lisp/buff-menu.el
@@ -530,10 +530,21 @@ Buffer-menu-multi-occur
(defun Buffer-menu-visit-tags-table ()
"Visit the tags table in the buffer on this line. See `visit-tags-table'."
(interactive nil Buffer-menu-mode)
- (let ((file (buffer-file-name (Buffer-menu-buffer t))))
- (if file
- (visit-tags-table file)
- (error "Specified buffer has no file"))))
+ (let* ((buffer (Buffer-menu-buffer t))
+ (file (buffer-file-name buffer)))
+ (or file
+ (error "Specified buffer has no file"))
+ ;; Ensure that it's really a tags file buffer (or the user at
+ ;; least believes it should be). Otherwise, visit-tags-table will
+ ;; change the mode and discard any undo information.
+ (if (not (or (eq (with-current-buffer buffer
+ major-mode)
+ 'tags-table-mode)
+ (yes-or-no-p
+ (format "%s is not a tags table; visit as such anyway? "
+ buffer))))
+ (error "Aborted."))
+ (visit-tags-table file)))
(defun Buffer-menu-1-window ()
"Select this line's buffer, alone, in full frame."
--
2.34.1
This bug report was last modified 3 years and 89 days ago.
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