c＆＃x2b;＆＃x2b;/winrt coroutine包括混乱

Question

我正在尝试关注此对于C ++/Winrt，我正在使用Universal C Runtime Clang推荐用于MSYS2 在这里。我正在使用Windows SDK 10.0.22621.0（目前最新的Windows 10最新目前可用于Windows 10）。 我正在遇到包括Coroutine头文件的错误，并正在寻求澄清。在“ Windows套件/10/include/inclate/incepty/cyper/cppwinrt/winrt/base.h”文件

#ifdef __cpp_lib_coroutine // not defined at this point because not included yet

#include <coroutine> // so this include doesn't happen...?
// This is my question, under what condition is this #ifdef block supposed to trigger?
// Because it should and it isn't.

namespace winrt::impl
{
    template <typename T = void>
    using coroutine_handle = std::coroutine_handle<T>;

    using suspend_always = std::suspend_always;
    using suspend_never = std::suspend_never;
}

#else


// and instead this include happens, which is incorrect because coroutine is not
// experimental as of early 2019 (https://en.cppreference.com/w/cpp/utility/feature_test)
// https://en.cppreference.com/w/cpp/header/coroutine
#include <experimental/coroutine>

namespace winrt::impl
{
    template <typename T = void>
    using coroutine_handle = std::experimental::coroutine_handle<T>;

    using suspend_always = std::experimental::suspend_always;
    using suspend_never = std::experimental::suspend_never;
}

#endif

中菜鸟问题有一个简单的答案，但是我一直在为此挣扎了几个小时，感谢您的任何见解。