bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Pieter van Oostrum]

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,  Eli
>>  Zaretskii <eliz@gnu.org>
>> Date: Mon, 09 Mar 2020 14:26:19 +0100
>> 
>> OK, with this change I get sensible information:
>> 
>> (gdb) f 9
>> #9  0x0000000100314bfe in Ffuncall (nargs=2, args=0x7ffeefbf6e78)
>>     at eval.c:2796
>> 2796     val = funcall_lambda (fun, numargs, args + 1);
>> (gdb) p args[0]
>> $50 = XIL(0xcfeb420)
>> (gdb) xtype
>> Lisp_Symbol
>> (gdb) xsymbol
>> $51 = (struct Lisp_Symbol *) 0x10da24150
>> "vm-set-summary-pointer"
>
> Thanks (and thanks to Paul for making GD|B usable in this case).
>
> So does vm-set-summary-pointer indeed call mapatoms as part of its
> job?  If so, can you show the relevant code fragment(s)?

You probably mean vm-update-summary-and-mode-line (in frame #24). That one 
indeed calls mapatoms. It uses it to find all the buffers. I don't know why 
they don't use '(buffer-list)'.
And then that calls vm-do-needed-summary-rebuild which calls 
vm-set-summary-pointer

But anyway, this shouldn't crash emacs.

By the way, with Paul's patch, I now do get a normal Lisp backtrace. It's equal 
to what I got the hard way:

Lisp Backtrace:
"vm-set-summary-pointer" (0xefbf6e80)
"vm-do-needed-summary-rebuild" (0xefbf7e50)
0x5c5b460 PVEC_COMPILED
"mapatoms" (0xefbf91a0)
"vm-update-summary-and-mode-line" (0xefbfa1c0)
"vm" (0xefbfb610)
"vm-visit-folder" (0xefbfc960)
"funcall-interactively" (0xefbfc958)
"call-interactively" (0xefbfd9c0)
"command-execute" (0xefbfea20)
(gdb) 

I include the whole Elisp file with these functions.

vm-summary.el
Description: application/emacs-lisp

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