bug#63587: 29.0.91; package-menu-mark-upgrades does not show available upgrades

[Andreas Kurth <emacs@akurth.de>]

Philip wrote:
> I've taken a look at the issue, and think this small change should fix
> the issue:
> 
> diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
> index 325c7b4e0a6..01826da273d 100644
> --- a/lisp/emacs-lisp/package.el
> +++ b/lisp/emacs-lisp/package.el
> @@ -3751,8 +3751,8 @@ package-menu--find-upgrades
>          (and avail-pkg
>               (version-list-< (package-desc-priority-version pkg-desc)
>                               (package-desc-priority-version avail-pkg))
> -             (xor (not package-install-upgrade-built-in)
> -                  (package--active-built-in-p pkg-desc))
> +             (or (not (package--active-built-in-p pkg-desc))
> +                 package-install-upgrade-built-in)
>               (push (cons name avail-pkg) upgrades))))
>      upgrades))
> 
> 
> And before I just propose a different change, I'd like to try and prove
> that it fixes the above issue.  For a package with an update, let
> 
> p := is a built-in package
> q := built-in packages should be upgradede
> 
> The previous implementation with xor (p ⊻ q) correctly decides to
> upgrade or not-upgrade the package in three of the four possible cases
> 
> p q   upgrade? 
> --------------
> t f   f
> t t   t
> f t   f        <-- this was Andreas case
> f f   t
> 
> But since non-built-in packages should always be upgraded, we need to
> change the condition to only be false when we have a built-in package
> but `package-install-upgrade-built-in' is non-nil:
> 
>       ¬ (¬ q ∧ p)
>     = ¬¬ q ∨ ¬p
>     = q ∨ ¬p
> 
> as we see, this should solve the issue:
> 
> p q   upgrade? (p ∨ ¬q)
> --------------
> t f   f
> t t   t
> f t   t
> f f   t
> 
> Does this look OK?


This sounds reasonable and looks like the natural implementation to me
(I’m not a proficient elisp developer though).

I applied the patch and already got an update for a non-built-in
package.

Thanks, Andreas.