[libcxx] What degree of Windows and/or MSVC support is already present?

I’ve seen some commits (largely from smeenai) that deal with Microsoft technologies. I’m curious as to what is currently supported, and what is in progress, as it is relevant to my aspirations of Windows kernel support with MSVC 2017.

Is any Microsoft platform as a target supported from any compiler? Is any Microsoft compiler supported?

I know the tests have had substantial fixes and restructuring in order to be used by the Microsoft libraries team (STL et al). If libcxx itself has some configuration that works though, I’d like to know how to set it up so that I don’t break it.

I’ve seen some commits (largely from smeenai) that deal with Microsoft
technologies. I’m curious as to what is currently supported, and what is
in progress, as it is relevant to my aspirations of Windows kernel support
with MSVC 2017.

I wouldn't call anything regarding Windows "supported" at this stage. At
best any support is experimental and in-progress. Right now we're trying to
get to the point
where the Windows build doesn't regress.

Is any Microsoft compiler supported?

No Microsoft compiler is supported; It's Clang only right now.

Is any Microsoft platform as a target supported from any compiler?

I'm not 100% sure I understand the question, but I'll try and answer.

I've only built libc++ natively on Windows 10 using Clang 4.0 with either
MSVC 2015 or 2017 as the native toolchain.