i installed the default version of clang and llvm in my ubuntu 14.04 and it's version 3.4. That's nice, but for some legacy stuff i need version 2.9. Ideally, i could install both version in parallel ...
I am an unskilled Ubuntu user and almost each time I try to install something nontrivial I break something miserably. I am successfully using gcc 4.7 and 4.8 simultaneously using update-alternatives ...