bug#39164: 27.0.60; Intermittent crash on MacOS 10.14 in setup_process_coding_systems

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Justin Guenther <jguenther@gmail.com>,  39164@debbugs.gnu.org
> Date: Mon, 20 Jan 2020 10:15:28 +0100
> 
> >>>>> On Fri, 17 Jan 2020 23:01:10 +0200, Eli Zaretskii <eliz@gnu.org> said:
> 
>     Eli> Thanks, but the backtraces don't show any source information, and it
>     Eli> is very hard to do anything about this without that.  Can you tell
>     Eli> where in coding.c is setup_process_coding_systems + 152?
> 
> Iʼm on 10.14, and donʼt see this crash. Assuming my emacs-27 build is
> similar to Justin's, itʼs this:
> 
> 7988      setup_coding_system (coding_system, 
> proc_decode_coding_system[inch]);
>    0x000000010019645f <+143>:   mov    (%r12,%r15,8),%rsi
>    0x0000000100196463 <+147>:   callq  0x10007b610 <setup_coding_system>
> 
> 7989
> 7990      if (!proc_encode_coding_system[outch])
>    0x0000000100196468 <+152>:   lea    0x4d3061(%rip),%r15        # 
> 0x1006694d0
>    0x000000010019646f <+159>:   mov    (%r15,%r14,8),%rsi
>    0x0000000100196473 <+163>:   test   %rsi,%rsi
>    0x0000000100196476 <+166>:   jne    0x100196489 
> <setup_process_coding_systems+185>

Does this mean proc_encode_coding_system is NULL (or garbled), or the
value of outch is outlandish (or garbled)?  Showing the values of
these variables will be appreciated.