bug#63731: [PATCH] Support Emoji Variation Sequence 16 (FE0F) where appropriate

[Robert Pluim <rpluim@gmail.com>]

>>>>> On Mon, 05 Jun 2023 16:47:22 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Robert Pluim <rpluim@gmail.com>
    >> Cc: 63731@debbugs.gnu.org,  steven@stebalien.com
    >> Date: Mon, 05 Jun 2023 15:36:52 +0200
    >> 
    >> >>>>> On Mon, 05 Jun 2023 16:12:20 +0300, Eli Zaretskii <eliz@gnu.org> said:
    >> 
    Eli> This is simple enough to install on emacs-29, I think?
    >> 
    >> The main change is in font.c, and looks like this. I think itʼs too
    >> big for emacs-29 (breaking composition is very easy, itʼs entirely
    >> possible Iʼve missed a few cases :-) )

    Eli> Hmm... I though just changing the fontset in fontset.el would be
    Eli> enough.

Itʼs almost enough to do that, and to check if the triggering
character is U+FE0E, bu then we fall foul of the composition rule
forward/backward issue again.

If we could have forward and backwards looking rules working together,
then font_range would get passed U+FE0F or U+FE0E as the triggering
character, it could choose the font, and there would be no need to
peek at the next character.

Robert
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