bug#62248: 29.0.60; nil obsolete

[Michael Welsh Duggan <mwd@md5i.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: luangruo@yahoo.com
>> From: Michael Welsh Duggan <mwd@md5i.com>
>> Date: Sat, 18 Mar 2023 02:52:57 -0400
>> 
>> Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text
>> editors" <bug-gnu-emacs@gnu.org> writes:
>> 
>> > Type:
>> >
>> >   C-h v nil RET
>> >
>> > Emacs will describe `nil' as obsolete since 29.1.
>> > That is absurd.
>> 
>> Happens for me too, but not with -Q.  So some common package is causing
>> this, likely by accident.
>
> Can you step through help-fns--var-obsolete and tell what you see
> there?  E.g., does (get nil 'byte-obsolete-variable) return non-nil?
>
> If so, how about running Emacs with a breakpoint in Fput and condition
> that symbol == Qnil (assuming your Emacs is not configured to
> represent Lisp objects as structs)?

I traced it, in my instance, to this line from url-gw.el:

(make-obsolete-variable url-gw-rlogin-obsolete-warned-once nil "29.1")

Maybe `make-obsolete-variable' should warn or error with nil as its
initial argument.

-- 
Michael Welsh Duggan
(md5i@md5i.com)