[PATCH] D22034: [MSVC][DLL] use local vftable mangling only exported classes with virtual destructor

Wed Jul 6 03:35:16 PDT 2016

majnemer added a comment.

In http://reviews.llvm.org/D22034#474937, @DmitryPolukhin wrote:

> David, do you know real programs that relay on constexpr and dllexport semantic that doesn't work on MSVC?

Yes, Chrome relied on these semantics.

> Anyway current implementation is not compatible with MSVC in much more common case without constexp.

I don't see how it is not compatible.  The address of the vftable is not observable as far as I know...

> At the moment my patch works with your example just because it only changes mangling but don't use imported vftable that seems to be wrong.

Why is it //wrong//?  It should obey the ABI in all practical matters but it might be less efficient space-wise.

http://reviews.llvm.org/D22034