Le lundi 07 août 2006 à 08:24 +0200, Bjørn Roald a écrit :
I don't think you can dual license GPL with _less_ restrictive licenses, e.g. the Boost license. Those licenses add too much freedom. Freedom to use and hide is not compatible with the GPL. That said, you can use Boost Software Licensed software in a GPL project. That is what the GPL compatibility pages is about:
[...]
Q: Can I dual-license my software under both the GPL and the Boost Software License? A: The Boost Software License allow this, but not the GPL. This is not allowed due to the copyleft restrictions in the GPL. See: http://www.gnu.org/copyleft/#WhatIsCopyleft. Specifically, the problem is with the GPL requiring all modified and extended versions of the program to be free as well. The Boost Software License allow the licensee to make non-free modified and extended versions of the program.
I don't agree with this interpretation. When you multi-license a "software", the "user" is not bound by all the licenses at once. In particular, breaking one of the licenses does not simultaneously break all the other licenses. As a consequence, if the user is allowed to "use" the software under the terms of the GPL and if she is also allowed to use it under the terms of the Boost license, she can decide that the only the Boost license applies and then she can use the software in strict accordance with this license. Best regards, Guillaume