The mangling of std::aligned_union depends on support for variadic templates in that specializations of the template will be mangled differently depending on whether _RWSTD_NO_VARIADIC_TEMPLATES is #defined or not. It seems that it should be possible to assure compatible mangling between the two, but I'm not 100% sure, and if it is, that it's worth the effort. There might be other templates where we may not easily be able to achieve compatibility.
I suppose the big question then is: should we try to fortify the implementation against ABI changes caused by changes in the techniques used in the implementation of C++ 0x? In the past we didn't concern ourselves with this issue but since we can expect compilers to only start supporting some of the new core language features such as variadic templates only slowly and piecemeal, a few at a time, I think it's a concern that we need to address early on. Thoughts? Martin
