bug#59311: 29.0.50; tab-bar global-mode-string affected by global-display-line-numbers

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: gabriel376@hotmail.com,  59311@debbugs.gnu.org
> Date: Sun, 20 Nov 2022 10:20:40 +0200
> 
> > No, because line-numbers take space, and some use cases of
> > buffer-text-pixel-size want to know that.  Only the caller knows whether the
> > line-numbers should or shouldn't be included.  The principle is that we
> > measure the space taken in the text-area, no matter how it is used.  (There
> > are other display features that affect the result, for example,
> > line-prefix.)
> 
> I still don't understand why string-pixel-width should handle line-numbers
> that also degrades its performance.

Because string-pixel-width uses a temporary buffer as its internal
implementation detail.  (And why do you think this degrades performance? any
measurements?)

> I think it should be sufficient only
> to disable line-numbers in internal buffers.

I think it's too late for that, since display-line-numbers-mode is with us
for the last 2 major releases.

> But ok, here are both:
> 
> diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
> index 6e4d88b4df..fba817b010 100644
> --- a/lisp/emacs-lisp/subr-x.el
> +++ b/lisp/emacs-lisp/subr-x.el
> @@ -324,7 +324,8 @@ string-pixel-width
>      (with-current-buffer (get-buffer-create " *string-pixel-width*")
>        (delete-region (point-min) (point-max))
>        (insert string)
> -      (car (buffer-text-pixel-size nil nil t)))))
> +      (- (car (buffer-text-pixel-size nil nil t))
> +         (line-number-display-width t)))))

This is fine by me.  (Or you could turn off display-line-numbers-mode
instead, right after with-current-buffer.)

>  ;;;###autoload
>  (defun string-glyph-split (string)
> diff --git a/lisp/display-line-numbers.el b/lisp/display-line-numbers.el
> index 897a88398f..cf5d353fba 100644
> --- a/lisp/display-line-numbers.el
> +++ b/lisp/display-line-numbers.el
> @@ -101,7 +101,8 @@ display-line-numbers-mode
>  
>  (defun display-line-numbers--turn-on ()
>    "Turn on `display-line-numbers-mode'."
> -  (unless (minibufferp)
> +  (unless (or (minibufferp)
> +              (string-match-p "\\` " (buffer-name)))
>      (display-line-numbers-mode)))

I don't agree with this part.

Thanks.