On Tue, Dec 8, 2009 at 6:10 PM, Erik de Castro Lopo
Tom Tobin wrote:
The background situation: X is a library distributed under the GPL. Y is another library that uses that library and requires it in order to compile and function.
You probably also need to bring in application Z which uses library X via library Y, because library Y is not usable by itself.
I think this is implicit in calling something a library; are there any questions where it would come up?
1) Is there any scenario where Y can be distributed under a non-GPL license (e.g., the BSD)?
You need to make sure they know that your are talking about the 3 clause BSD license, the one the FSF calls the Modified BSD license.
Good point.
3) If Y must be released under the GPL under the above scenario, and someone subsequently wrote library Z, an API compatible replacement for X, and released it under the BSD license, would Y's author now be permitted to release Y under the BSD?
The author is always allowed to relicense their own work under whatever license they choose.
Well I think that's actually what we're wondering here — under what circumstances is Y's author permitted to choose his license at will?
For instance there are libraries released under the GPL which are also available under a commercial use license for use in closed source products. The requirement here is that the library is soley written by the person doing the dual licensing and/or all other contributors have assigned their rights.
But those libraries don't, in turn, depend on GPL'd libraries written by different authors. I think the answer to the "can Y's author choose the BSD3 for Y" question will also answer this for cases where there's a further, different-author GPL dependency involved.