bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Eli Zaretskii]

> From: Pieter van Oostrum <pieter-l@vanoostrum.org>
> Cc: 39962@debbugs.gnu.org,  pieter@vanoostrum.org
> Date: Sat, 07 Mar 2020 18:21:47 +0100
> 
> > Can you show the full C backtrace?
> >
> (gdb) bt
> #0  terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:371
> #1  0x00000001002a4abb in die (
>     msg=0x10050ff57 "m->bytepos >= m->charpos && m->bytepos - m->charpos <= 
> Z_BYTE - Z", file=0x10050fdda "insdel.c", line=295) at alloc.c:7246
> #2  0x0000000100233af4 in adjust_markers_for_insert (from=36399, 
>     from_byte=36399, to=36401, to_byte=36401, before_markers=false)
>     at insdel.c:294
> #3  0x00000001002344d0 in insert_from_string_1 (string=XIL(0x15b29a904), 
>     pos=0, pos_byte=0, nchars=2, nbytes=2, inherit=false, 
> before_markers=false)
>     at insdel.c:1060
> #4  0x0000000100233e18 in insert_from_string (string=XIL(0x15b29a904), pos=0, 
>     pos_byte=0, length=2, length_byte=2, inherit=false) at insdel.c:967
> #5  0x00000001002ec4c2 in general_insert_function (
>     insert_func=0x1002320b0 <insert>, 
>     insert_from_string_func=0x100233d80 <insert_from_string>, inherit=false, 
>     nargs=1, args=0x7ffeefbf5ce8) at editfns.c:1334
> #6  0x00000001002ec1db in Finsert (nargs=1, args=0x7ffeefbf5ce8)
>     at editfns.c:1370

Thanks.  Since xbacktrace doesn't work in your case for some reason
(which is troublesome on its own), I will have to ask you to go to
every frame that calls Ffuncall, and do this:

  (gdb) p args[0]
  (gdb) xtype

If "xtype" says it's a symbol, then additionally do this immediately
after "xtype":

  (gdb) xsymbol

This will tell us which Lisp function was called in each such frame: a
poor man's Lisp backtrace.

Are these problems something you can trigger at will?