bug#67810: 29.1; fonts use synthetic bold on Linux / pgtk

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: crypto@timruffing.de,  stefankangas@gmail.com,  67810@debbugs.gnu.org
> Date: Sat, 13 Jan 2024 08:46:28 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Sorry, I don't understand what you are saying here.  Could you please
> > say it in simpler words?  What are "icon fonts"? and what do you mean
> > by "it can be removed"?
> 
> Fonts designed to provide symbol icons, which are inserted by packages
> that can control the `face' property of the text inserted.  Such fonts
> don't provide bold variants, and they did prompt this bug report.

So you are talking about fonts that use PUA codepoints to show icons?
Or are you talking about fonts whose glyphs for "normal" characters
(i.e. characters defined by the Unicode Standard) are replaced with
icons that look similarly?

> > If we add such a variable, it will be opt-in behavior, so only users
> > who want it will get the behavior that you consider deficient.  It
> > will be then up to those users to decide whether the behavior is good
> > enough for them.  So I see no problem with such an option; we don't
> > have to like each and every optional behavior that is by default
> > turned off.
> 
> What if a user wants to disable the `bold' attribute for a font _with_
> a bold variant?

That's not the feature I had in mind.  I don't see why Emacs should
allow users to disable font variants that do exist.  AFAIU, the
request was to prevent Emacs from creating a synthesized bold variant
if the font doesn't have it, and that's all.  How to find such a font
is a problem outside of Emacs's scope.