bug#33014: 26.1.50; 27.0.50; Fatal error after re-evaluating a thread's function

[Eli Zaretskii <eliz@gnu.org>]

> From: Gemini Lasswell <gazally@runbox.com>
> Cc: 33014@debbugs.gnu.org,  schwab@linux-m68k.org
> Date: Thu, 18 Oct 2018 17:39:54 -0700
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >   (gdb) p fun
> >   (gdb) xpr
> >
> > Let me know if this isn't what you meant.
> 
> I meant something like 'pv', as in:
> 
> (gdb) pv emacs-version
> "27.0.50"
> 
> but which I could use to find out what the bytecode object for
> erb--benchmark-monitor-func is.

But a function doesn't have to be byte-compiled, in which case there's
no bytecode.  Look at the implementation of funcall, and you will see
how Emacs deals with this.  It seemed to me that xpr reflects that, in
that it shows you what object to look at for a given function symbol.

If you are sure the function is already compiled, then funcall_lambda
will show you how it invokes exec_byte_code for such a function, and
you will see there how to access the bytecode of such a function.

HTH

P.S. Patches to .gdbinit to provide such a functionality in a new
command, called, say, "xfunc", will be most welcome, of course.