bug#46662: [PATCH] cl-extra: Fix docstring retrieval

bug#46662: [PATCH] cl-extra: Fix docstring retrieval

[Julian Scheid]

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Given

  (require 'cl-macs)
  (cl-defstruct foobar
    (baz nil :documentation "an important piece of information"))

Now, (describe-symbol 'foobar-baz) will include "an important piece of
information".

However, (describe-symbol 'foobar) will not:

Name Type Default
———— ———— ———————
baz t nil

... even though the intention to include it can be seen by looking for
the string ':documentation' in `cl--describe-class-slots`.

This is because `cl--describe-class-slots` accidentally uses
`alist-get` instead of `plist-get`.

With the attached patch, (describe-symbol 'foobar) works as intended:

Name Type Default Doc
———— ———— ——————— ———
baz t nil an important piece of information

Note: `cl--describe-class-slot' (a different function) appears to have
the same bug, but I have no idea how one would go about adding class
slots to a struct and therefore no way of testing any changes to this
other function.

Could it be a code path that is never executed anyway?  I decided to
leave it alone, this patch should be an improvement regardless.

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From d9b67052a595d03f228c61d05b0906ea74b0ee4e Mon Sep 17 00:00:00 2001
From: Julian Scheid <julians37@gmail.com>
Date: Sun, 21 Feb 2021 00:15:52 +1300
Subject: [PATCH] cl-extra: Fix docstring retrieval

* lisp/emacs-lisp/cl-extra.el (cl--describe-class-slots): Fix
  docstring retrieval.
---
 lisp/emacs-lisp/cl-extra.el | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/emacs-lisp/cl-extra.el b/lisp/emacs-lisp/cl-extra.el
index 28ce6b115a..84199c1612 100644
--- a/lisp/emacs-lisp/cl-extra.el
+++ b/lisp/emacs-lisp/cl-extra.el
@@ -898,8 +898,8 @@ cl--describe-class-slots
                (list (cl-prin1-to-string (cl--slot-descriptor-name slot))
                      (cl-prin1-to-string (cl--slot-descriptor-type slot))
                      (cl-prin1-to-string (cl--slot-descriptor-initform slot))
-                     (let ((doc (alist-get :documentation
-                                           (cl--slot-descriptor-props slot))))
+                     (let ((doc (plist-get (cl--slot-descriptor-props slot)
+                                           :documentation)))
                        (if (not doc) ""
                          (setq has-doc t)
                          (substitute-command-keys doc)))))
-- 
2.30.1

bug#46662: [PATCH] cl-extra: Fix docstring retrieval

[Lars Ingebrigtsen]

Julian Scheid <julians37@gmail.com> writes:

> With the attached patch, (describe-symbol 'foobar) works as intended:
>
> Name Type Default Doc
> ———— ———— ——————— ———
> baz t nil an important piece of information

Thanks; applied to Emacs 28.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no