bug#70760: 29.3.50; core dumps when copy in other apps

[Eli Zaretskii <eliz@gnu.org>]

> From: Kun Liu <kun.liu@gmail.com>
> Date: Sat, 4 May 2024 11:08:31 -0700
> Cc: 70760@debbugs.gnu.org
> 
> (gdb) xtype data
> Lisp_Cons
> (gdb) xcar data
> $2 = 0x11f40
> (gdb) xcdr data
> $3 = 0x0
> (gdb) xstring data
> $4 = (struct Lisp_String *) 0x0
> "DEAD"

This is not how you explore a cons cell in GDB.  The correct sequence
is:

  (gdb) print data
  (gdb) xtype

If "xtype" says it's a cons cell, the next command should be "xcar",
followed by "xtype", to show the type of car.  If "xtype" says it's a
symbol, the next command should be "xsymbol", to show the symbol's
name.  Once you are done with car, continue to cdr, like this:

  (gdb) print data
  (gdb) xcdr
  (gdb) xtype

Then again use the appropriate command given what "xtype" says.  Etc.,
etc.

Also, do you remember what you did in Emacs when it crashed?  Was it
C-y or something similar?