Re: LLVM

[David Chisnall]

On 1 Mar 2008, at 14:16, Helge Hess wrote:

> So far I didn't read the license of clang, but wouldn't it be  
> possible to license changes we do under GPL? (pretty much in the  
> same line what you fear Apple could do ;-)

The license for clang and LLVM is BSD-style.  There is nothing  
stopping you from writing GPL'd patches (the license is GPL- 
compatible, but the GPL is not UIOSL compatible), but they won't be  
accepted upstream.  If you have the resources to maintain a complete  
GPL'd fork of clang, then feel free.  I don't.

On 1 Mar 2008, at 14:17, Nicola Pero wrote:

> The license determines the duty and rights of the various parties;  
> because
> at the moment we are the "weak" party in any effort to write and  
> maintain
> an Objective-C compiler/runtime (weak in comparison to Apple), it is  
> important
> to look at the license and think about how it protects our interests  
> - particularly
> in the worst case scenario. :-(
>
> It's easy to assume that Apple will always be nice to the community  
> and so the
> license does not matter, but in fact it does, particularly in the  
> long term.
>
> If Apple will always be nice to the community, why don't they change  
> the license
> to explicitly say so ? :-)

It does explicitly say so.  The code is Free.  Apple can not close  
it.  They can close a fork of it at a future date, but that is  
unlikely to happen because a lot of people outside Apple are working  
on LLVM and they would lose access to all of those developers if they  
did.  And if they do, what do we lose?  Apple's future contributions  
to the code, something that GCC is already losing precisely because of  
its license.

They are not going to release it under a license which says that they  
have to open every project that links to it, because that would mean  
they'd have to open their OpenGL implementation (uses LLVM to compile  
GLSL for the CPU), XCode (uses clang for refactoring tools and syntax  
highlighting), and so on.

All of LLVM, including clang, is developed in a University of Illinois  
svn repository.  It is not an Apple project, just one that Apple are  
willing to contribute a lot of time to.  They could not change the  
license without getting approval from the University of Illinois even  
if they wanted to, and the UoI would not give this because then they  
would also not get contributions from other commercial entities who  
want to use it in their own closed products.

Maybe I'm an idealist, but I prefer the kind of freedom that comes  
from choice.

David