bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Pieter van Oostrum <pieter-l@vanoostrum.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Pieter van Oostrum <pieter-l@vanoostrum.org>
>> Cc: Pieter van Oostrum <pieter@vanoostrum.org>,  39962@debbugs.gnu.org
>> Date: Sat, 07 Mar 2020 12:06:50 +0100
>> 
>> insdel.c:295: Emacs fatal error: assertion failed: m->bytepos >=
>> m->charpos && m->bytepos - m->charpos <= Z_BYTE - Z
>> --Type <RET> for more, q to quit, c to continue without paging--
>> insdel.c:295: Emacs fatal error: assertion failed: m->bytepos >=
>> m->charpos && m->bytepos - m->charpos <= Z_BYTE - Z
>
> Please show the values of the variables involved in this assertion.

(gdb) f 2
#2  0x0000000100233af4 in adjust_markers_for_insert (from=36399, 
    from_byte=36399, to=36401, to_byte=36401, before_markers=false)
    at insdel.c:294
294	      eassert (m->bytepos >= m->charpos
(gdb) p m
$1 = (struct Lisp_Marker *) 0x1609db830
(gdb) p m->bytepos
$2 = 11538
(gdb) p m->charpos
$3 = 0
(gdb) p Z_BYTE
No symbol "Z_BYTE" in current context.
(gdb) p Z
No symbol "Z" in current context.
(gdb) p current_buffer->text->z_byte
No symbol "current_buffer" in current context.
(gdb) p current_buffer
No symbol "current_buffer" in current context.
(gdb) p current_thread->m_current_buffer
$4 = (struct buffer *) 0x15b29a4b0
(gdb) p current_thread->m_current_buffer->text->z_byte
$5 = 529784
(gdb) p current_thread->m_current_buffer->text->z
$6 = 529778
(gdb)

>
>> Lisp Backtrace:
>> Cannot access memory at address 0xcfeb5c0
>
> This last bit is highly suspicious.  Something is going on in addition
> to the assertion violation, and that something might be the actual
> reason for the assertion.
>
> Also note that this is no longer in GC, at least not directly.

That's right. Although the cause of this might also have caused the GC problem when the assertion would not have caught it.
-- 
Pieter van Oostrum
www: http://pieter.vanoostrum.org/
PGP key: [8DAE142BE17999C4]