I can only comment on the specific llvm case, but I cannot say "it works" without listing the fact that I have to keep ~5-6 versions of llvm around _exactly_ fo

I can only comment on the specific llvm case, but I cannot say "it works" without listing the fact that I have to keep ~5-6 versions of llvm around _exactly_ for that reason. You cannot compare an OS, or in general any product which is "complete by itself" (browsers), with a compiler which is then used to _make_ the end product. Your source depends on it, and as it grows it just becomes increasingly hard to keep up. Rolling releases are /also/ a tradeoff. I'm not particularly pleased with llvm in this case. I genuinely prefer semantic releases, and yes, even the python2->3 strategy in this context.