Microsoft has released a new Windows 10 Preview Build of the SDK to be used in conjunction with Windows 10 Insider Preview (Build 17120 or greater)
What’s NewWindows 10 SDK Preview Build 17120 released
C++/WinRT Now Available: The C++/WinRT headers and cppwinrt compiler (cppwinrt.exe) are now included in the Windows SDK. The compiler comes in handy if you need to consume a third-party WinRT component or if you need to author your own WinRT components with C++/WinRT. The easiest way to get working with it after installing the Windows Insider Preview SDK is to start the Visual Studio Developer Command Prompt and run the compiler in that environment. Authoring support is currently experimental and subject to change. Stay tuned as we will publish more detailed instructions on how to use the compiler in the coming week.The ModernCPP blog has a deeper dive into the CppWinRT compiler. Please give us feedback by creating an issue at: https://github.com/microsoft/cppwinrt.