Heads up: Mesa/LLVM rebase and OpenGTL retirement in F20

[Kevin Kofler]

Kalev Lember wrote:
> This might be a good way forward for Fedora as well to avoid changing
> the system-wide llvm ABI mid release.

No, most definitely not! Let me introduce you to our old "friend", the 
symbol conflict.

By way of libGL linking LLVM, if some other library uses a private LLVM, and 
an application links both libGL and that library, it crashes due to symbol 
conflicts. And this is EXACTLY what already happened with OpenGTL on several 
distributions, including Fedora:
http://www.valdyas.org/fading/index.cgi/2011/10/08#llvm
The only fix for that issue, and the one we implemented, was linking OpenGTL 
(and also Mesa, which had also been using a private LLVM before) against the 
system LLVM. The distros which didn't do that kept having that fatal crash.

Now, it turns out that the current Krita no longer uses OpenGTL, and I'm not 
aware of any application using it, so I don't really care what you do to it 
anymore. (We already retired it in Rawhide.) But please DO NOT use a private 
LLVM in any other package (and especially not in Mesa – again, to avoid the 
symbol conflicts, BOTH Mesa AND the other LLVM-using package(s) MUST link to 
the shared LLVM library). You WILL hit this same issue. You have been 
warned.

        Kevin Kofler