Subject: Re: bug#77381: [PATCH] extend tex--prettify-symbols-alist

From: Eli Zaretskii <[email-masked]>
Date: Sun, 30 Mar 2025 19:50:38 +0300

> From: "Paul D. Nelson" <[email-masked]>
> Cc: [email-masked]
> Date: Sun, 30 Mar 2025 18:21:44 +0200
> 
> > Ideally, we should only add those which can be displayed.  The
> > function char-displayable-p should be able to tell.  Would it be
> > possible to change the code such that only the symbols that pass that
> > test are added?
> 
> I tried, but wasn't able to extract the necessary information from
> char-displayable-p:
> 
> In GUI Emacs,
> 
>   (char-displayable-p #x1F6F0) -> 'unicode
> 
> and that character is not displayable for me (it renders as a white
> square).
> 
> In Emacs -nw,
> 
>   (char-displayable-p #x1d550) -> 'unicode
> 
> but that character displays normally for me.

For a GUI frame, if char-displayable-p returns a symbol, the character
is not displayable.  Characters that can be displayed on a GUI frame
should cause char-displayable-p to return a string, the name of the
font suitable for the character.