bug#65270: 30.0.50; `describe-function' issue with some methods

[David Ponce <da_vid@orange.fr>]

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On 13/08/2023 12:36, David Ponce wrote:
> Hello,
> 
> It seems there is an issue with `describe-function' of a method that
> calls `cl-call-next-method'.  For a such method `describe-function' says
> that the method is "Undocumented" even if a doc string is present.
> 
> Also the mentioned signature is weird.  See an illustration below using
> a simple recipe, running 'emacs -Q'.
> 
[...]

Hello,

The attached patch fixed for me the doc string issue with `describe-function'
for methods calling `cl-call-next-method'.

It would be nice if someone who better knows the cl-generic library will
double check it (CC Stefan, the author).

Unfortunately, I didn't find a solution for arguments.

Hope it will help.

Thanks

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diff --git a/lisp/emacs-lisp/cl-generic.el b/lisp/emacs-lisp/cl-generic.el
index b062c280a41..722211d6ba8 100644
--- a/lisp/emacs-lisp/cl-generic.el
+++ b/lisp/emacs-lisp/cl-generic.el
@@ -429,6 +429,15 @@ cl-generic-define-context-rewriter
             (lexical-binding
              (cons 'curried
                    `#'(lambda (,nm) ;Called when constructing the effective method.
+                        ,@(let* ((prebody (car parsed-body))
+                                 (ds (if (stringp (car prebody))
+                                         prebody
+                                       (setq prebody (cons nil prebody))))
+                                 (usage (help-split-fundoc (car ds) nil)))
+                            (unless usage
+                              (setcar ds (help-add-fundoc-usage (car ds)
+                                                                args)))
+                            prebody)
                         (let ((,nmp (if (cl--generic-isnot-nnm-p ,nm)
                                         #'always #'ignore)))
                           ;; This `(λ (&rest x) .. (apply (λ (args) ..) x))'
@@ -446,15 +455,6 @@ cl-generic-define-context-rewriter
                           ;; is always called directly and there are no
                           ;; `&optional' args.
                           (lambda (&rest ,arglist)
-                            ,@(let* ((prebody (car parsed-body))
-                                     (ds (if (stringp (car prebody))
-                                             prebody
-                                           (setq prebody (cons nil prebody))))
-                                     (usage (help-split-fundoc (car ds) nil)))
-                                (unless usage
-                                  (setcar ds (help-add-fundoc-usage (car ds)
-                                                                    args)))
-                                prebody)
                             (let ((,cnm (lambda (&rest args)
                                           (apply ,nm (or args ,arglist)))))
                               ;; This `apply+lambda' basically parses