Since the GNU General Public License v3 had been [released last week](http://gplv3.fsf.org/) I’m actively thinking about switching the license for some of my projects, f.e. [guitone](http://guitone.thomaskeller.biz), which are currently GPLv2 “or later”. The main reason for doing this for me personally is to protect my software even better from any possible [Tivoization](http://en.wikipedia.org/wiki/Tivoization), i.e. no patent restrictions, closed hardware, or anything else should hinder people to use, modify and distribute it further.
Looking more in detail at the license possibilities [Trolltech](http://www.trolltech.com) gives developers which use their Qt/Qtopia platform, upgrading Qt projects from GPLv2 to GPLv3 doesn’t seem to be possible: The problem is that even though Qt4 can be licensed under GPLv2, it does **not** contain the “… or – at your option – any later version” clause of the license, and since GPLv2 and GPLv3 are incompatible with each other, as Richard Stallman [told us here](http://gplv3.fsf.org/rms-why.html), you therefor can’t legally link GPLv3 code with those GPLv2 libraries:
> When we say that GPLv2 and GPLv3 are incompatible, it means there is no legal way to combine code under GPLv2 with code under GPLv3 in a single program. This is because both GPLv2 and GPLv3 are copyleft licenses: each of them says, If you include code under this license in a larger program, the larger program must be under this license too.? There is no way to make them compatible. We could add a GPLv2-compatibility clause to GPLv3, but it wouldn’t do the job, because GPLv2 would need a similar clause.
([Source](http://gplv3.fsf.org/rms-why.html))
There _might_ be a way out of this dilemma, in case Trolltech doesn’t want to put Qt/Qtopia directly under “GPLv2 or later”/GPLv3: There already seems to exist a “Trolltech GPL Exception version 1.0”, but the text is currently unavailable from the [Troll’s site](http://trolltech.com/products/qt/gplexception). A temporary copy of it can be found in the Subversion repository of the libqxt project. The Exception states that you can use a couple of other accepted Free Software Licenses in your project and still use the GPL version of Qt:
> […] 1) The right to use Open Source Licenses not compatible with the GNU General Public License: You may link software (hereafter referred to as “Your Software”) against the Licensed Software and/or distribute binaries of Your Software linked against the Licensed Software, provided that:
> A) Your Software is licensed under one of the following licenses: […]
and what follows is a list which includes licenses like the Apache Software License, the LGPL, the BSD license, the Mozilla Public License, to just name a few. Furthermore:
> […] B) You must, on request, make a complete package including the complete source code of Your Software (as defined in the GNU General Public License version 2, section 3, but excluding anything excluded by the special exception in the same section) available to Trolltech under the same license as that granted to other recipients of the source code of Your Software. […]
…this seems only fair…
> […] C) Your or any other contributor’s rights to:
> i) distribute the source code of Your Software to anyone for any purpose;
> and
> ii) publicly discuss the development project for Your Software and its goals in any form and in any forumare not prohibited by any legal instrument, including but not limited to contracts, non-disclosure agreements, and employee contracts. […]
… yes I hope so!
Now I’m unsure if this exception is granted to every (free) software project using Qt. Currently, GPLv3 is not on the list, but if this exception is valid for everyone (not just paid customers of Trolltech), maybe it could be expanded to allow GPLv3 as well and therefor serve the Open Source community
Whatever route Trolltech will go, I hope they at least notice that there is **a demand from the Open Source community** to clarify the licensing issues with respect to GPLv3, and I hope this happens in the near future…
Edit 2007-08-09
It seems as Trolltech put back the GPL Exception in place, though the GPLv3 is still not listed as a valid license. One Trolltech engineer said however recently in a comment on the Labs Blog:
… As for GPL v3, we are actively working on it. From what I understand, it is a bigger step and not something we can just provide with an Exception.
(Source)
So its good to know that they’re aware of it!