bug#39962: 27.0.90; Crash in Emacs 27.0.90

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

Pip Cet <pipcet@gmail.com> writes:

> On Wed, Mar 11, 2020 at 3:16 PM Pieter van Oostrum
> <pieter-l@vanoostrum.org> wrote:
>> > (prog1
>> >     (let ((temp-buffer (generate-new-buffer " *temp*")))
>> >       (prog1
>> >           temp-buffer
>> >         (kill-buffer temp-buffer)
>> >         (setq temp-buffer nil)))
>> >   (garbage-collect))
>>
>> That crash shouldn't happen, so it has to be found what causes it.
>
> The attached patch should fix things.

With this patch I still get a crash. This time a sementation violation again in the garbage collector. So that doesn't solve the problem I am encountering.

GDB bailed out for some reason (I get the impression that GDB on MacOS isn't very stable).
But here is what I got:


Thread 3 received signal SIGSEGV, Segmentation fault.
0x00000001002b5000 in vector_marked_p (v=0x160249fd0) at alloc.c:3715
3715	  if (pdumper_object_p (v))
(gdb) bt 10
#0  0x00000001002b5000 in vector_marked_p (v=0x160249fd0) at alloc.c:3715
#1  0x00000001002b369f in mark_object (arg=XIL(0x160249fd5)) at alloc.c:6480
#2  0x00000001002b5813 in mark_vectorlike (header=0x160249f50) at alloc.c:6157
#3  0x00000001002b391a in mark_object (arg=XIL(0x160249f55)) at alloc.c:6566
#4  0x00000001002b5813 in mark_vectorlike (header=0x160249e60) at alloc.c:6157
#5  0x00000001002b391a in mark_object (arg=XIL(0x160249e65)) at alloc.c:6566
#6  0x00000001002b3d33 in mark_object (arg=XIL(0x167929583)) at alloc.c:6628
#7  0x00000001002b3b04 in mark_object (arg=XIL(0x515dcd0)) at alloc.c:6585
#8  0x00000001002b5813 in mark_vectorlike (header=0x11ddd20f0) at alloc.c:6157
#9  0x00000001002b391a in mark_object (arg=XIL(0x11ddd20f5)) at alloc.c:6566
(More stack frames follow...)
Warning:
Cannot insert breakpoint 0.
Cannot access memory at address 0x7ffeef270f7f

Command aborted.
An error occurred while in a function called from GDB.
Evaluation of the expression containing the function
(backtrace_top) will be abandoned.
When the function is done executing, GDB will silently stop.

[1]+  Stopped                 gdb ~/Projects/Emacs/nextstep/Emacs.app/Contents/MacOS/Emacs
src $ bt
-bash: bt: command not found
src $ fg
gdb ~/Projects/Emacs/nextstep/Emacs.app/Contents/MacOS/Emacs
(gdb) bt
#0  backtrace_top () at eval.c:176
Backtrace stopped: Cannot access memory at address 0x7ffeef270f68
Warning:
Cannot insert breakpoint 0.
Cannot access memory at address 0x7ffeef270edf
Cannot insert breakpoint 0.
Cannot access memory at address 0x7ffeef270f7f

Command aborted.
An error occurred while in a function called from GDB.
Evaluation of the expression containing the function
(backtrace_top) will be abandoned.
When the function is done executing, GDB will silently stop.

[1]+  Stopped                 gdb ~/Projects/Emacs/nextstep/Emacs.app/Contents/MacOS/Emacs

-- 
Pieter van Oostrum
www: http://pieter.vanoostrum.org/
PGP key: [8DAE142BE17999C4]