[OE-core] [meta-clang] oe-core and meta-clang llvm coexsting?

[Martin Kelly]

Hi,

I'm trying to integrate the meta-clang version of LLVM 4.0 (used for 
recipes that need a newer LLVM version) alongside the oe-core version of 
LLVM 3.3 (used for mesa). I'd like some recipes to use LLVM 4.0 and some 
to use LLVM 3.3 and for them not to collide with each other.

Right now, once the meta-clang layer is enabled, the recipes collide 
because they both provide llvm-common.bb. I tried explicitly versioning 
llvm-common, which makes them no longer collide. However, mesa then 
fails to build because the meta-clang version of LLVM installs 
llvm-config into the native common sysroot in 
tmp/sysroots/x86_64-linux/usr/bin/llvm-config . This llvm-config is 
based on LLVM 4.0, so when mesa picks it up, it gets confused and fails 
to build.

I'm trying to figure out the right way to fix this and get around it. Do 
you have any suggestions? I imagine there might be a quick-and-dirty way 
to do this and a nicer, long-term way to do it. I'm interested in 
hearing both.

Thanks,
Martin