All this talk of yours about how conformant to the C++ standard Microsoft is becoming means nothing unless they can fix the preprocessor. The rest of your touting of how serious Microsoft is in conforming to the C++ standard is just "show business" to me. Whatever Microsoft ships as their backend compiler, whatever noises they make about being serious about conforming as closely as possible to the C++11 or C++14 or C++17 standards, if they can't ship a C++ standards preprocessor they will never be conformant to the C++ standard.
It seems google is happy https://randomascii.wordpress.com/2016/03/24/compiler-bugs-found-when-portin..., maybe boost should tell them that you're unhappy with the preprocessor and where it's buggy? Have a good day, degski