bug#73881: 31.0.50; Unexpected warnings about recursive occurrences of obsolete functions

[Eshel Yaron via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Hi,

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Sat, 19 Oct 2024 15:21:22 +0200
>> From:  Eshel Yaron via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> 
>> 
>> 1. emacs -Q
>> 2. (require 'allout) or otherwise load allout.el
>> 3. Byte-compile allout.el with M-x byte-compile-file
>> 4. See warnings:
>> 
>> --8<---------------cut here---------------start------------->8---
>> In allout-old-expose-topic:
>> allout.el:5092:29: Warning: ‘allout-old-expose-topic’ is an obsolete function
>>     (as of 28.1); use ‘allout-expose-topic’ instead.
>> allout.el:5097:44: Warning: ‘allout-old-expose-topic’ is an obsolete function
>>     (as of 28.1); use ‘allout-expose-topic’ instead.
>> allout.el:5106:8: Warning: ‘allout-old-expose-topic’ is an obsolete function
>>     (as of 28.1); use ‘allout-expose-topic’ instead.
>> --8<---------------cut here---------------end--------------->8---
>> 
>> These warnings are unhelpful since these are recursive calls within the
>> definition of the obsolete function itself.  They need not be replaced
>> with another function as the warnings suggest.  Ideally, recursive calls
>> to obsolete functions should not produce such warnings.
>
> From where I stand, this could be closed as wontfix, unless someone
> sees an easy fix.  I don't see any harm from emitting these warnings
> in this scenario.  The warnings are correct.

All right, FWIW I find them more distracting then helpful: if I'm
declaring a function as obsolete, that means it's going to stay around
for at least a short while, with its recursive calls, which I have no
interest in adapting.  So these warnings do not tell me anything useful.

As for an easy fix, maybe something like this?

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 29e7882c851..edb8160a250 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1533,6 +1533,7 @@ byte-compile-arglist-signature-string
 
 (defun byte-compile-function-warn (f nargs def)
   (when (and (get f 'byte-obsolete-info)
+             (not (eq f byte-compile-current-form)) ; Recursive call.
              (not (memq f byte-compile-not-obsolete-funcs)))
     (byte-compile-warn-obsolete f "function"))