Re: Unicode 13 Emoji ranges composed with wrong font on NS port

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Jimmy Yuen Ho Wong <wyuenho@gmail.com>,  Alan Third <alan@idiocy.org>,
>   emacs-devel@gnu.org
> Date: Tue, 12 Oct 2021 19:13:59 +0200
> 
> This turns out not to be due to macOS differences, but because of this
> code in lisp/composite.el:
> 
> (let ((elt '([".." 1 compose-gstring-for-variation-glyph])))
>   (set-char-table-range composition-function-table '(#xFE00 . #xFE0F) elt)
>   (set-char-table-range composition-function-table '(#xE0100 . #xE01EF) elt))
> 
> If I change that to use `compose-gstring-for-graphic' instead, then
> the emoji+VS-16 display works correctly on macOS and GNU/Linux.
> 
> Eli, something like the following for emacs-28?

That's because VS-16 is already handled by other entries, including
its own?  Or how will VS-16 be handled if you remove it from that
range?

And if the reason is that VS-16 is not about glyph variations, then
why not exempt VS-15 as well?  Or why we need that special entry for
VS-16 at all?

> +;; We don't want variation selectors to be used to look up glyphs for FE0F

The comment should explain why.  Right now, the comment just says what
the code does, but gives no reasons.

Thanks.