bug#37786: 26.3; Emacs crashes when calling function to decode string

[Robert Pluim]

>>>>> On Thu, 17 Oct 2019 21:28:35 -0700, Allen Li <darkfeline@felesatra.moe> 
>>>>> said:

    Allen> This is the backtrace using the simpler repro from Robert.

    Allen> #0  0x0000000000565ae9 in terminate_due_to_signal (sig=6, 
backtrace_limit=40) at emacs.c:363
    Allen> #1  0x000000000058ca83 in emacs_abort () at sysdep.c:2380
    Allen> #2  0x000000000045c17e in redisplay_internal () at xdisp.c:13797
    Allen> #3  0x000000000045e0b7 in redisplay_preserve_echo_area 
(from_where=13) at xdisp.c:14602
    Allen> #4  0x0000000000667fbe in Fdelete_process (process=XIL(0x6aa3395)) 
at process.c:1054
    Allen> #5  0x000000000067716b in kill_buffer_processes (buffer=XIL(0)) at 
process.c:7819
    Allen> #6  0x00000000005683d0 in shut_down_emacs (sig=0, stuff=XIL(0)) at 
emacs.c:2096
    Allen> #7 0x000000000052d854 in x_connection_closed (dpy=0x2b77f50,
    Allen> error_message=0x7fffffff6fc0 "X protocol error: BadLength (poly
    Allen> request too large or internal Xlib length error) on protocol request
    Allen> 139", ioerror=false) at xterm.c:9799

I thought weʼd fixed these kinds of bugs, but obviously not. Can you
try your test in combination with the following from etc/DEBUG, it
should tell us which font is responsible:

    For X protocol errors related to displaying unusual characters or to
    font-related customizations, try invoking Emacs like this:

      XFT_DEBUG=16 emacs -xrm "emacs.synchronous: true"

    This should produce information from the libXft library which could
    give useful hints regarding font-related problems in that library.

Regards

Robert