Le dimanche 07 juillet 2024 à 18:58 +0300, Eli Zaretskii a écrit :
> Probably.  Do you consider it a problem in Emacs or in Pango?


The Pango documentation explicitly states that Pango validates the input
and "renders invalid UTF-8 with a placeholder glyph".

  https://docs.gtk.org/Pango/method.Layout.set_text.html

Should it really emit a warning, in which case Emacs should do the
replacement itself to avoid the warning? Or should it just render the
text, with the placeholder glyph, without warning? I don't really
know.



> 
> [...]
> Once again, I described what we do in Emacs in the hope that it will
> help you find your own solution.  If it doesn't help, that's fine by
> me; there's no need to argue as long as what we do is understood.


Thank you for your insight; I think it's valuable, even though I don't
think this solution is the best for the particular tradeoffs of Guile
(but I agree that the problem is significant and the tradeoffs are not
easy).

BTW, let me make it clear that I'm not a Guile maintainer, just a lurker
like you.