Sorry, there is a typo in that quote. It should be ClassID.
That class will have to be modified to work correctly in the presence of shared libraries. For Linux I think it should mostly just work as-is(% maybe tweaking the visibility). For Windows DLL, I think we will have to fallback to comparing class names(using llvm::getTypeName?). It would help if we can start clarifying which problems are affecting which systems. This makes it easier as some systems, mainly MSVC, have no problems that can be worked around. I’m more than happy to fix this myself, but it would help to have some repro instructions that can be used for testing the various scenarios.