bug#33232: `gnus-summary-line-format' padding doesn’t work in gui when there are multiple-column-width characters

[Noam Postavsky <npostavs@gmail.com>]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> "Garreau, Alexandre" <galex-713@galex-713.eu> writes:
>
>> Given this (rectangular) excerpt from my bug-gnu-emacs summary:
>>> …01-nov…[-> 33224@debbugs.gnu.org        ] bug#33224: `message-simpli…
>>> …01-nov…[Noam Postavsky                  ] bug#33225: [debbugs.el] Do…
>>> …01-nov…[-> Noam Postavsky               ]  bug#33225: [debbugs.el] D…
>>> …01-nov…[積丹尼 Dan Jacobson             ] bug#33226: chromium, firef…
>>
>> On my system (Debian, with Xorg, i3, GUI Emacs), the last line has its
>> “]” sooner than the others.  This is because `gnus-correct-length'
>> (along with `char-width') says each of the first three characters is
>> two-columns wide: but under GUI, this is untrue, as these three
>> collectively form exactely 5 columns (and not six, as would calculate
>> `gnus-correct-length').
>
> Someone just reported something similar on the org list, that
> `string-width' doesn't return the actual width occupied by the string,
> which you'd think would be the whole point.

See Bug#31588, the width of these characters depends on the font, so
string-width (which works only on a string) can't give the right answer.
Or, from another point of view, it's the font's fault for being too
narrow on these characters.

> (BTW, it looks like `gnus-correct-length' can be replaced by
> `string-width'.)

Yep.