Subject: bug#71605: 30.0.50; [PATCH] Support variable-width text in 'visual-wrap-prefix-mode'

From: Jim Porter <[email-masked]>
Date: Mon, 17 Jun 2024 23:27:49 -0700

On 6/17/2024 8:02 PM, Jim Porter wrote:
> Just so others are aware I'm going to try and bisect this. I'll report 
> back when it's finished.

Looks like this is the commit that regressed this:

commit fb3d582e7ba595b7680e2c2adf22c7ab699e5792
Author: Eli Zaretskii <[email-masked]>
Date:   Wed Jun 29 20:15:36 2022 +0300

     Fix hscrolling of :align-to when display-line-numbers is in effect

     * src/dispextern.h (struct it): Rename 'tab_offset' member to
     'stretch_adjust'.
     * src/xdisp.c (gui_produce_glyphs, produce_stretch_glyph)
     (display_line): All users of 'tab_offset' changed.
     (produce_stretch_glyph): Fix calculation of ':align-to' when
     line numbers are displayed and the window is hscrolled.
     (calc_pixel_width_or_height): Fix calculation of width of 'space'
     display property when 'display-line-numbers' is turned on, but the
     line number was not yet produced for the current glyph row.
     (Bug#56176)

I'll take a look in more detail tomorrow, but if anyone else wants to 
fix this, go ahead. I also have a bit of Elisp that checks whether this 
feature works, and I should be able to make it into a proper regression 
test with a bit of work.