bug#64757: 30.0.50; Declare `defadvice` obsolete

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

Package: Emacs
Version: 30.0.50


The `nadvice` package introduced in Emacs-24.4 make the `advice.el`
package technically obsolete in the sense that everything that could be
done with `advice.el` could now be done with `nadvice.el` (indeed,
`advice.el` was reimplemented on that occasion to work on top of
`nadvice.el`).

While maintainers have converted their `defadvice` to the new
`advice-add` more slowly than the conversion from `cl` to `cl-lib`
(maybe because I was slower in rolling out a forward compatibility for
it in GNU ELPA, tho probably because the conversion takes a bit more
work), the new advice library has been very popular thanks to its
being simpler.

Emacs-29 is the first release that doesn't use the old advice library in
its own code at all, so I think Emacs-30 is a good time to mark
`defadvice` as obsolete.

I suggest to do it with the following patch, which should not introduce
any incompatibilities.


        Stefan


diff --git a/etc/NEWS b/etc/NEWS
index d1af3b1b866..54fb6ccac5c 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -614,6 +614,8 @@ provokes an error if used numerically.
 \f
 * Lisp Changes in Emacs 30.1
 
+** 'defadvice' is marked as obsolete.
+
 +++
 ** New user option 'safe-local-variable-directories'.
 This user option names directories in which Emacs will treat all
diff --git a/lisp/emacs-lisp/advice.el b/lisp/emacs-lisp/advice.el
index 56f0ae2212c..3265809f592 100644
--- a/lisp/emacs-lisp/advice.el
+++ b/lisp/emacs-lisp/advice.el
@@ -3131,6 +3131,7 @@ defadvice
           [DOCSTRING] [INTERACTIVE-FORM]
           BODY...)"
   (declare (doc-string 3) (indent 2)
+           (obsolete "use advice-add or define-advice" "30.1")
            (debug (&define name  ;; thing being advised.
                            (name ;; class is [&or "before" "around" "after"
                                  ;;               "activation" "deactivation"]