7.x (public) SDK had no support for C/C++ whatsoever, you needed special access and a private SDK to use it. Windows Phone 8.0 allowed C++ 11
Only starting with VS2015 (and then maybe even update 2 IIRC) we had what we can call C++ 11 (for the purpose of not having to port code for it, or such port to be easy, so missing 1 or 2 language and library features can be OK, but missing half of them: less so).