Can GPLv3 packages be synced?

[David Kastrup]

Mats Lidell <matsl at xemacs.org> writes:

> I have just released a version of Hyperbole under GPLv3. Can I sync
> this with the XEmacs Package Tree or need I maintain a v2 version in
> parallel for now?

If Hyperbole is written all by yourself, you can release under any
number of licenses (conflicting or not) simultaneously: no need to do
anything special.

If any upstream code you use has been released as GPLv3+, you can't
release as GPLv2 without asking the upstream author.

If you don't want to stop people from synchronizing your GPLv3
released code into a GPLv2 code base without having to ask you, there
is no point to releasing under anything but GPLv2+.

As long as you yourself are the person doing the synchronization, you
can release independently as GPLv3 or GPLv3+, but put your code into
XEmacs under GPLv2+.  This is sort of pointless, however, since people
can then always pull the GPLv2+ version from XEmacs.  So if you feel
that GPLv3 is a better license than GPLv2, you want to use it, and you
still want to contribute to a GPLv2+ XEmacs, you should fork your
codebase, so that the XEmacs specific version licensed GPLv2+ is not
useful outside of XEmacs (basically, remove all Emacs compatibility
code).

Of course, this seems sort of brain dead.  Once XEmacs considers
synchronizing to newer Emacs packages, it will have to decide whether
to go GPLv3 or stop synchronizing, anyway.  So perhaps you can just
stay with GPLv2+ until that point of time and spare yourself the
hassle.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum