At this time, VCV uses the GNU General Public License v3.0 license for most of our published free/open-source projects.
If, however, the Free Software Foundation releases a new GPL version in the future, say GPLv3.1 or GPLv4, software released under this license would be “incompatible” with VCV’s code. For example, a GPLv4 project might not be able to use VCV’s code, and VCV might not be able to use the GPLv4 project’s code, depending on whether the GPLv4 is more restrictive (>), more permissive (<), or neither (≠).
The solution to this problem is for VCV to license software under “GPLv3 or later”, which gives the code multiple licenses to choose from, if for example someone needs to consider its code as licensed under GPLv4.
This has been requested by 5-6 Rack users in the past year, and I had a short conversation with Richard Stallman himself about license incompatibilities and the possibility of future GPL versions, so I plan to add the “or later” clause to all future releases of VCV’s GPLv3-licensed projects. I encourage all developers of GPLv3 plugins to consider adding the “or later” clause if you believe in this logic. If you do, see https://www.gnu.org/licenses/gpl-3.0.en.html#howto and remember to change the license identifier in plugin.json from "GPL-3.0-only" to "GPL-3.0-or-later".
This is an extremely minor change right now, perhaps not even worth making an announcement about it, but it will be extremely important if a new GPL version is released.
I was expecting someone to make that point. While it is possible that the Free Software Foundation might publish a new version of the GPL that is too permissive, it is a hypothetical and unlikely scenario, whereas the problem of license incompatibility will be a real and 100% likely problem if and when a new version is published. GPL incompatibilities cause real (not hypothetical) legal friction today between GPLv2 and GPLv3 software, and they will do the same with GPLv3 and “GPLv4”.
I’m just curious and I’m absolutely no licensing expert: Could I not add „or later“ at any time in the future? Would it be a problem to change a license from „GPLv3 only“ to „GPLv3 or later“ when the next version of GPL is published and if I agree with these terms?
If you remain the sole owner of your source code, you will be able to relicense your software at any time. Then, if you license your software under GPLv3-only now, if and when “GPLv4” is published, you can choose to relicense your software under “either GPLv3 or GPLv4 of your choice”, or if you don’t like the license, don’t relicense. However, if you accept source code contributions without a Contributor License Agreement (CLA), you will not be able to relicense without all contributors’ permission.
Well, the reason that I require a CLA for pull requests to VCV Rack is much simpler than the GPL discussion: Since I plan to use all Rack code in a proprietary fork (VCV Rack for DAWs), I need to own the copyright over the entire source code.
Not really, that’s what happened with GPL 2 → 3, and it understandably upset a lot of people, including Linus. “Too permissive” is not really what matters, different terms in the future that you may or may not agree with is what matters.
If a future GPL version is too restrictive, that doesn’t really affect software licensed as “GPLv3 or later”, since users can choose the most permissive license, which in this scenario would be the GPLv3. On the other hand, if the GPLv4 is too permissive for the software owner’s taste, that would be a problem, but it is far more likely for future GPL licenses to become more restrictive than more permissive.
If feel that for most free software developers, their priorities for choosing a license that it’s free software, open-source, and copyleft. The specific terms of the GPL are less important. I believe that if the FSF publishes a new GPL version, it will definitely still have those aspects.