bug#62746: [PATCH] Updated Elispref-Manual: `nil' cannot be defuned

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Shynur Xie <one.last.kiss@outlook.com>,  62746@debbugs.gnu.org
> Date: Mon, 10 Apr 2023 10:14:59 -0400
> 
> >> “The symbols nil and void are Lisp objects, and can be stored into a
> >>  function cell just as any other object can be (and they can be valid
> >>  functions if you define them in turn with defun).”
> >> 
> >> Updated:
> >> 
> >> “The symbols nil and void are Lisp objects, and can be stored into a
> >>  function cell just as any other object can be (and void can be a
> >>  valid function if you define it with defun).”
> >
> > Why do you think the original text needs to be corrected?
> 
> Indeed, `nil` is treated specially to mean "not defined" when we try to
> call a function:
> 
>     Lisp_Object
>     funcall_general (Lisp_Object fun, ptrdiff_t numargs, Lisp_Object *args)
>     {
>       Lisp_Object original_fun = fun;
>      retry:
>       if (SYMBOLP (fun) && !NILP (fun)
>           && (fun = XSYMBOL (fun)->u.s.function, SYMBOLP (fun)))
>         fun = indirect_function (fun);
>     
>       if (SUBRP (fun) && !SUBR_NATIVE_COMPILED_DYNP (fun))
>         return funcall_subr (XSUBR (fun), numargs, args);
>       else if (COMPILEDP (fun)
>                || SUBR_NATIVE_COMPILED_DYNP (fun)
>                || MODULE_FUNCTIONP (fun))
>         return funcall_lambda (fun, numargs, args);
>       else
>         {
>           if (NILP (fun))
>             xsignal1 (Qvoid_function, original_fun);
> 

Thanks.  So I think our documentation is correct in this aspect, and
I'm therefore closing this bug.