bug#30672: 26.0.91, Font face lost ?

[Eli Zaretskii <eliz@gnu.org>]

> From: Fabrice Popineau <fabrice.popineau@gmail.com>
> Date: Fri, 2 Mar 2018 11:29:11 +0100
> Cc: 30672@debbugs.gnu.org
> 
>  then please explain what you mean by
>  "the font face is lost".
> 
>  (I cannot afford repeating your recipe, because it requires installing
>  weird fonts on my system.  Sorry.)
> 
> I attach 2 screen captures to show the problem. 
> 
> First image is the glyph selection and second image shows that the font has been lost
> somehow ("no font available").

Thanks, but the images don't provide the important information
required to understand what is going on.  The characters used by those
fonts to display the icons are from Private Use Areas (PUA) of the
Unicode codepoints, so it is quite OK for Emacs not to support them
without tricks or customizations.  It is those tricks that I expected
you to describe -- what does the package do to display these PUA
characters in the buffer(s) where you do see them.  Probably some
specialized text properties or some such (which is why I asked about
yank-excluded-properties).  E.g., what does describe-text-properties
say about those icons in the buffer where they display as icons?

> I hope it is not related to my own build with mingw64 but it has definitely worked with 
> some previous version of the same emacs-26 branch. Without any other clue,
> I'll try to rewind the branch and see if I can track some related change.

You could try bisecting, but I think a better way forward would be to
understand how the package arranges for these PUA characters to
display as icons, then we might get an idea which changes to look for.

One way of making these codepoints display everywhere as glyphs from
those special fonts is to customize your fontset, btw.