Right, added likely in response to this post.

https://source.ind.ie/project/phoenix/commit/4fc86be27e05662...

Thrown GPL on it, which doesn't exactly come across as considered - aren't a lot of Apples contributions to and development of Clang - including of course the objective c frontent, under the BSD-alike licence that it shares with LLVM?

Being that this is essentially part of the GNUstep project (of which Greg Casamento is the maintainer), which uses the GPL for all its application-level code, it's not surprising.