[llvm-dev] RFC: Improving license & patent issues in the LLVM community

[Chris Lattner via llvm-dev]

> On Oct 19, 2015, at 10:57 AM, Renato Golin <renato.golin at linaro.org> wrote:
> 
> On 19 October 2015 at 18:12, David Chisnall via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> One worry is that Apache 2 is incompatible with GPLv2 (is it incompatible with other licenses?)
> 
> This is interesting, I did not know that...
> 
> http://www.apache.org/licenses/GPL-compatibility.html
> 
> "Despite our best efforts, the FSF has never considered the Apache
> License to be compatible with GPL version 2, citing the patent
> termination and indemnification provisions as restrictions not present
> in the older GPL license."
> 
> It seems to be compatible with GPLv3, though. But I think most
> companies that use LLVM are stuck with GPLv2 due to the patents issue.

Yes, this is a known concern with the Apache 2 license, but I don’t know if there is an actual “known” answer to this question.  DannyB or someone else can comment for sure, but my understanding is that the terms of the GPL2 prevent *any* license from including the sort of patent protection that we are looking for.

FWIW, this is what the FSF has to say about the topic:
http://www.gnu.org/licenses/license-list.en.html#apache2

Note that the FSF *recommends* the Apache 2 license for permissively licensed projects.

If you are still concerned about this issue, my question is simply: what specific GPL2 compiler (or other user) that might want to use LLVM would be affected?

-Chris