bug#69306: 30.0.50; defining menu-items with :enable enables them unconditionally

[Eli Zaretskii <eliz@gnu.org>]

> From: StrawberryTea <look@strawberrytea.xyz>
> Cc: 69306@debbugs.gnu.org
> Date: Thu, 22 Feb 2024 15:19:26 -0600
> 
> Basically, I am trying to define a conditional keybinding. The real-world
> example I’m working with is:
> 
> (when-let ((cmds-del (and (modulep! :completion corfu +tng)
>                           ’(menu-item “Reset completion” corfu-reset
>                             :enable (and (> corfu–index -1)
>                                          (eq corfu-preview-current ’insert)))))
>            (cmds-ret ’(menu-item “Insert completion” corfu-insert
>                        :filter (lambda (cmd)
>                                  (if (eq corfu–index -1)
>                                      (corfu-quit)
>                                    cmd)))))
>   (map! :when (modulep! :completion corfu)
>         :after corfu
>         :map corfu-map
>         [backspace] cmds-del
>         “DEL” cmds-del
>         :ig [return] cmds-ret
>         :ig “RET” cmds-ret))
> 
> Here, the :filter and :enable properties are used to conditionally enable their
> respective keybindings. The :filter property works as expected, but the :enable
> property does not. The backspace keybinding is always enabled, even when the
> :enable property is evaluates to nil.

If you expect that the key binding will be disabled via :enable, then
I don't think this is supported except in menus (and tool bars and tab
bars): the value is evaluated by the menu-related code, when it
actually displays the menu, and in your case there's no menu.  The
:filter attribute is interpreted differently, so it just happens to
work.  But that's sheer luck, I'd say.

Adding Stefan in case he has comments.