bug#13824: 24.3.50; :package-version not taking priority over :version

[Bill Wohler]

Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Stefan Kangas <stefan@marxist.se>
> > Date: Thu, 8 Aug 2019 05:59:21 +0200
> > Cc: 13824@debbugs.gnu.org
> > 
> > Bastien Guerry <bzg@altern.org> writes:
> > 
> > > The docstring of `defcustom' says:
> > >
> > > :package-version
> > >         VALUE should be a list with the form (PACKAGE . VERSION)
> > >         specifying that the variable was first introduced, or its
> > >         default value was changed, in PACKAGE version VERSION.  This
> > >         keyword takes priority over :version.
> > >         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > >
> > > but `describe-variable-custom-version-info' gives priority to :version
> > > over :package-version.  Which one is correct here?
> > 
> > This is still an issue on current master (and 26.2).
> > 
> > I reproduced this using:
> > 
> >     (progn
> >       (defcustom foobar nil
> >         "foo"
> >         :version "27.1"
> >         :package-version '(foo . "1"))
> >       (describe-variable-custom-version-info 'foobar))
> > 
> > Which results in:
> > 
> >     "This variable was introduced, or its default value was changed, in
> >     version 27.1 of Emacs.
> >     "
> > 
> > But C-h f defcustom says:
> > 
> >     :package-version
> >             VALUE should be a list with the form (PACKAGE . VERSION)
> >             specifying that the variable was first introduced, or its
> >             default value was changed, in PACKAGE version VERSION.  This
> >             keyword takes priority over :version.
> 
> The implementation only prefers :package-version for the purposes of
> customize-changed-options, i.e. the Options->Customize Emacs->New
> Options menu item.  By contrast, describe-variable-custom-version-info
> is used for displaying the doc strings of options.  For a package that
> is bundled with Emacs, I think displaying :version in "C-h v" makes
> sense.  If people agree, then this is a minor documentation bug (also
> to be fixed in the ELisp manual), not a code bug.
> 
> Bill, what is your take on this?  Your change, which introduced this
> attribute, only modified customize-changed-options.  Was that on
> purpose?

Thanks for asking. The original intent of package-version was to provide
more accurate version information in packages that were updated more
often than Emacs, regardless of whether they were packaged in Emacs
(like MH-E and Gnus) or not. I think that should apply to any function
that displays version information for an option. That is, any function
that looks for :version should also look for :package-version.

-- 
Bill Wohler <wohler@newt.com> aka <Bill.Wohler@nasa.gov>
http://www.newt.com/wohler/, GnuPG ID:610BD9AD