Subject: Re: bug#75725: SIGSEGV in emacs 30.0.93

From: Eli Zaretskii <[email-masked]>
Date: Wed, 22 Jan 2025 16:34:49 +0200

> Date: Wed, 22 Jan 2025 08:06:42 +0100
> From: Florian Franzmann <[email-masked]>
> Cc: [email-masked]
> 
> > > Maybe using MartianMono as doom-symbol-font is problematic?
> > 
> > I don't know yet.  Which characters is doom-symbol-font used for?
> > 
> > But you could try that hypothesis by using some other font there, and
> > seeing if the previous build of Emacs still crashes then.
> > 
> > Also, any idea which font is used on the mode line, and
> > what part of the mode line uses the '(raise FACTOR)' display property
> > there?  That's the part where the display code hit the font = NULL
> > condition.
> In my modeline there is one character that for which there doesn't
> seem to be a glyph, unicode F418. gucharmap shows that one as a symbol
> for a version-control branch in MartianMono Nerd Font, I don't
> understand why emacs doesn't find the symbol, the rest of the modeline
> looks like it's using that font.

U+F418 is a private-use character.  Emacs knows nothing about such
characters, since their meaning is entirely up to the applications
and/or fonts that assigns the meaning to them.  So if doom-emacs uses
such characters on the mode line, it must somehow arrange for that to
happen, since the "normal" font-selection machinery in Emacs doesn't
work for PUA characters.

So I'm afraid I cannot be of much help here, as I don't know how
doom-emacs do this.