Emacs daemon crashes when scrolling through a buffer. I believe it
happens when buffer is trying to display Arabic letters that are in my
mail summary buffer. I used "git bisect" and found that this is the
first "bad" commit:


    commit 30a7ee505aca3cc285699bae1630a28185519d99
    Author: Eli Zaretskii <eliz@gnu.org>
    Date:   2020-06-05 10:56:01 +0300

        Fix Arabic shaping when eww/shr fill the text to be rendered

        * src/hbfont.c (hbfont_shape): Don't use DIRECTION if the current
        buffer has bidi reordering disabled.  (Bug#41005)


My Emacs daemon process is managed by systemd and the logs have this
backtrace:


    emacs[9121]: Backtrace:
    emacs[9121]: /usr/local/bin/emacs(+0x1385b7)[0x55e55be3c5b7]
    emacs[9121]: /usr/local/bin/emacs(+0x437ff)[0x55e55bd477ff]
    emacs[9121]: /usr/local/bin/emacs(+0x43c3c)[0x55e55bd47c3c]
    emacs[9121]: /usr/local/bin/emacs(+0x136f88)[0x55e55be3af88]
    emacs[9121]: /usr/local/bin/emacs(+0x137009)[0x55e55be3b009]
    emacs[9121]: /lib/x86_64-linux-gnu/libpthread.so.0(+0x12730)[0x7f0c4b462730]
    emacs[9121]: /usr/local/bin/emacs(+0xd8c80)[0x55e55bddcc80]
    emacs[9121]: /usr/local/bin/emacs(+0xdcff2)[0x55e55bde0ff2]
    emacs[9121]: /usr/lib/x86_64-linux-gnu/libharfbuzz.so.0(+0x9b5be)[0x7f0c4b70d
    emacs[9121]: /usr/lib/x86_64-linux-gnu/libharfbuzz.so.0(hb_shape_plan_execute
    emacs[9121]: /usr/lib/x86_64-linux-gnu/libharfbuzz.so.0(hb_shape_full+0x46)[0
    emacs[9121]: /usr/local/bin/emacs(+0x1fe65c)[0x55e55bf0265c]
    emacs[9121]: /usr/local/bin/emacs(+0x1a3c4b)[0x55e55bea7c4b]
    emacs[9121]: /usr/local/bin/emacs(+0x193a03)[0x55e55be97a03]
    emacs[9121]: /usr/local/bin/emacs(+0x1c7471)[0x55e55becb471]
    emacs[9121]: /usr/local/bin/emacs(+0x195fba)[0x55e55be99fba]
    emacs[9121]: /usr/local/bin/emacs(+0x19395f)[0x55e55be9795f]
    emacs[9121]: /usr/local/bin/emacs(+0x1c7471)[0x55e55becb471]
    emacs[9121]: /usr/local/bin/emacs(+0x195fba)[0x55e55be99fba]
    emacs[9121]: /usr/local/bin/emacs(+0x19395f)[0x55e55be9795f]
    emacs[9121]: /usr/local/bin/emacs(+0x192ed6)[0x55e55be96ed6]
    emacs[9121]: /usr/local/bin/emacs(+0x5f425)[0x55e55bd63425]
    emacs[9121]: /usr/local/bin/emacs(+0x6c8ff)[0x55e55bd708ff]
    emacs[9121]: /usr/local/bin/emacs(+0x1e94b3)[0x55e55beed4b3]
    emacs[9121]: /usr/local/bin/emacs(+0x1ec86b)[0x55e55bef086b]
    emacs[9121]: /usr/local/bin/emacs(+0x7879b)[0x55e55bd7c79b]
    emacs[9121]: /usr/local/bin/emacs(+0x78332)[0x55e55bd7c332]
    emacs[9121]: /usr/local/bin/emacs(+0x769f5)[0x55e55bd7a9f5]
    emacs[9121]: /usr/local/bin/emacs(+0x7e658)[0x55e55bd82658]
    emacs[9121]: /usr/local/bin/emacs(+0x83dfb)[0x55e55bd87dfb]
    emacs[9121]: /usr/local/bin/emacs(+0x97fba)[0x55e55bd9bfba]
    emacs[9121]: /usr/local/bin/emacs(+0x9bafb)[0x55e55bd9fafb]
    emacs[9121]: /usr/local/bin/emacs(+0x192d9a)[0x55e55be96d9a]
    emacs[9121]: /usr/local/bin/emacs(+0x67154)[0x55e55bd6b154]
    emacs[9121]: /usr/local/bin/emacs(+0x875bd)[0x55e55bd8b5bd]
    emacs[9121]: /usr/local/bin/emacs(+0x129c67)[0x55e55be2dc67]
    emacs[9121]: /usr/local/bin/emacs(+0x12c5bc)[0x55e55be305bc]
    emacs[9121]: /usr/local/bin/emacs(+0x12dbfc)[0x55e55be31bfc]
    emacs[9121]: /usr/local/bin/emacs(+0x192d02)[0x55e55be96d02]
    emacs[9121]: /usr/local/bin/emacs(+0x11fad4)[0x55e55be23ad4]
    emacs[9121]: /usr/local/bin/emacs(+0x192c81)[0x55e55be96c81]
    emacs[9121]: ...
    systemd[1044]: emacs.service: Main process exited, code=killed, status=11/SEG
    systemd[1044]: emacs.service: Failed with result 'signal'.

-- 
/// Teemu Likonen - .-.. http://www.iki.fi/tlikonen/
// OpenPGP: 4E1055DC84E9DFF613D78557719D69D324539450