[HarfBuzz] HarfBuzz crash when shaping Arabic?

[Eli Zaretskii]

Could someone please look at this Emacs bug report:

  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=42352

and tell if something like this rings a bell?

According to the backtrace, the crash happened inside HarfBuzz (the
backtrace levels above that are the Emacs signal handling mechanism).
The user who reported that uses HarfBuzz 2.3.1 as packaged by Debian:

  https://debbugs.gnu.org/cgi/bugreport.cgi?bug=42352#28

The crash happened when some Arabic text was passed to hb_shape_full
without providing the explicit direction of the text, but instead
relying on hb_buffer_guess_segment_properties to guess it.

Was there perhaps a problem in that version of HarfBuzz that could
crash like that?

TIA