bug#39962: 27.0.90; Crash in Emacs 27.0.90

[Eli Zaretskii]

> 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)?