bug#62959: [PATCH] Recognize defstruct slot names in various eieio functions

[Eli Zaretskii <eliz@gnu.org>]

> From: Thuna <thuna.cing@gmail.com>
> Date: Thu, 20 Apr 2023 00:15:50 +0200
> 
> The function `eieio--known-slot-name-p' is used by some eieio functions
> (specifically eieio-oref, eieio-oref-default, and eieio-oset-default) to
> check whether a slot name is known or not, and if not signals an
> "Unknown slot" warning.
> 
> Structs do not make their slots known to `eieio--known-slot-name-p', so
> the warning is signaled even for valid slot names.  Since eieio aims for
> compatibility with defstruct, this should probably be considered a bug.
> 
> The function `eieio--known-slot-name-p' checks the variable
> `eieio--known-slot-names' but also has a fallback for the name's
> `slot-name' property.  In the patch I opted to use the latter.
> 
> 
> >From 86ed1ed7d024a0d40286d5fe4697258dc98a1b9e Mon Sep 17 00:00:00 2001
> From: Thuna <thuna.cing@gmail.com>
> Date: Wed, 19 Apr 2023 23:43:22 +0200
> Subject: [PATCH] Recognize defstruct slot names in various eieio functions
> 
> * lisp/emacs-lisp/cl-preloaded.el (cl-struct-define): Set each slot's
> name's `slot-name' property so that `eieio--known-slot-name-p' can
> recognize them.
> ---
>  lisp/emacs-lisp/cl-preloaded.el | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lisp/emacs-lisp/cl-preloaded.el b/lisp/emacs-lisp/cl-preloaded.el
> index 9445093f143..5235be52996 100644
> --- a/lisp/emacs-lisp/cl-preloaded.el
> +++ b/lisp/emacs-lisp/cl-preloaded.el
> @@ -176,6 +176,7 @@ cl-struct-define
>                         (i 0)
>                         (offset (if type 0 1)))
>                     (dolist (slot slots)
> +                     (put (car slot) 'slot-name t)
>                       (let* ((props (cl--plist-to-alist (cddr slot)))
>                              (typep (assq :type props))
>                              (type (if (null typep) t
> -- 
> 2.39.2
> 

Stefan, any comments?