I'm seeing that shared_mutex is supported with _M_CEE, whereas mutex is not.
And both are banned on include level under _M_CEE_PURE.

What is the situation with C++ support for _M_CEE?

Are _M_CEE and _M_CEE_PURE the only .Net modes, so that other special modes like C++/CX or OneCore are usual compilation, with full C++ support?