GNU bug report logs - #67248
30.0.50; string-pixel-width is affected by the global value of display-line-numbers

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Dmitry Gutov <dgutov <at> yandex.ru>
Subject: bug#67248: closed (Re: bug#67248: 30.0.50; string-pixel-width is
 affected by the global value of display-line-numbers)
Date: Sat, 18 Nov 2023 16:37:02 +0000

[Message part 1 (text/plain, inline)]

Your bug report

#67248: 30.0.50; string-pixel-width is affected by the global value of display-line-numbers

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 67248 <at> debbugs.gnu.org.

-- 
67248: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=67248
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Dmitry Gutov <dgutov <at> yandex.ru>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 67248-done <at> debbugs.gnu.org
Subject: Re: bug#67248: 30.0.50; string-pixel-width is affected by the global
 value of display-line-numbers
Date: Sat, 18 Nov 2023 18:36:08 +0200

Version: 29.2

On 18/11/2023 09:14, Eli Zaretskii wrote:
> I don't see a need for such drastic measures, certainly not due to
> this bug.  Having the variable and the mode in this case is not
> different from other similar cases, for example, word-wrap vs
> visual-line-mode.

At least word-wrap and visual-line-mode have different names. And the 
latter provides a bunch of other features than the former.

display-line-numbers and display-line-numbers-mode sound totally 
identical, so I'm not at all surprised that the author of the referenced 
bug report customized both of them. That's a usability problem.

> Thanks, I think this is indeed the right solution.  Please install the
patch on the emacs-29 branch.

Okay, pushed as 0128495afde. Thanks.

[Message part 3 (message/rfc822, inline)]

From: Dmitry Gutov <dgutov <at> yandex.ru>
To: bug-gnu-emacs <at> gnu.org
Subject: 30.0.50; string-pixel-width is affected by the global value of
 display-line-numbers
Date: Fri, 17 Nov 2023 23:23:58 +0200

1. (string-pixel-width "abc") ; => 51
2. (customize-set-variable 'display-line-numbers t)
3. (string-pixel-width "abc") ; => 119

This function's implementation makes provision for
display-line-numbers-mode, but not for the original variable
display-line-numbers, which will be t independent of the value of
display-line-numbers-mode.

I think it's a bad idea to have these two different ways to do the same
thing, and it can lead to bugs like this one. I would suggest obsoleting
the public use of display-line-numbers -- making it private, probably.
At least removing it from the customization group display-line-numbers.

Barring that, the patch below seems to work.  Although it proliferates
the differences between Emacs versions which one would have to be on the
lookout for.

Originally reported at
https://github.com/company-mode/company-mode/issues/1427.

diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 572822351b1..4fda98ae3d0 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -343,8 +343,7 @@ string-pixel-width
     (with-current-buffer (get-buffer-create " *string-pixel-width*")
       ;; If `display-line-numbers-mode' is enabled in internal
       ;; buffers, it breaks width calculation, so disable it (bug#59311)
-      (when (bound-and-true-p display-line-numbers-mode)
-        (display-line-numbers-mode -1))
+      (setq-local display-line-numbers nil)
       (delete-region (point-min) (point-max))
       ;; Disable line-prefix and wrap-prefix, for the same reason.
       (setq line-prefix nil


In GNU Emacs 30.0.50 (build 271, x86_64-pc-linux-gnu, GTK+ Version
 3.24.34, cairo version 1.16.0) of 2023-11-17 built on potemkin
Repository revision: 94849ba35f40393362050b5937578dcf3076b4bf
Repository branch: feature/cl-lib-improvements
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Ubuntu 22.10

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