bug#56789: 28.1.90; Emoji composition problems with Harfbuzz 5.0.1-1

[Robert Pluim]

>>>>> On Wed, 27 Jul 2022 06:10:06 +0000, Simon Pugnet <simon@polaris64.net> 
>>>>> said:

    Simon> I have just updated the Harfbuzz package in Arch Linux to
    Simon> harfbuzz-5.0.1-1 and I've noticed that some emojis are no longer
    Simon> displayed properly. From an initial investigation it appears to be
    Simon> only composed sequences that have problems.

    Simon> Instead of seeing a correctly composed emoji sequence as before, I 
now
    Simon> only see an empty box with a single-pixel border.

What does hb-view show? Something like

hb-view  --output-file=foo.svg --font-size=13 \
/usr/share/fonts/truetype/noto/NotoColorEmoji.ttf \
-u 1f469,200d,2764,fe0f,200d,1f468

and then display foo.svg

    Simon> I'm not sure if this is a bug in Emacs or Harfbuzz however it only
    Simon> started happening after the upgrade to 5.0.1-1

I donʼt think weʼve changed anything in this area recently. Certainly
not on the emacs-28 branch.

Robert
--