bug#36758: 27.0.50; Mac OS/Lucid/X11: crash with libharfbuzz

[Simon Leinen]

Dear Mitshuaru,

thank you for your prompt reply and clear instructions - this is very
helpful for me as I don't have any experience with lldb!

> Could you try the following instructions?

>   1. recompile Emacs with CFLAGS="-O0 -g3"
>   2. run it under lldb.
>   3. run GNUS and wait for crash happens.
>   4. repeat lldb "up" command until it reaches emacs`ftfont_list
>      (frame #12 in the original stack trace)
>   5. run "p file" under lldb.

(lldb) p file
(FcChar8 *) $0 = 0x00000001071522e0 "/System/Library/Fonts/ArabicUIDisplay.ttc"

The file exists

: leinen@macsl[leinen]; ls -l /System/Library/Fonts/ArabicUIDisplay.ttc
-rw-r--r--  1 root  wheel  983632 Aug 18  2018 
/System/Library/Fonts/ArabicUIDisplay.ttc

Maybe the code has issue with right-to-left scripts?
-- 
Simon.