Microsoft yesterday released Windows 10 SDK Preview Build 17709 to developers. This SDK can be used with the recently released Windows 10 Insider Build 1770 or later. This updated SDK comes with bug fixes and changes to the API surface area. Microsoft has added several new APIs related to Windows Machine Learning, Light effects, and more. You can find the list of new API additions here.
Other changes in this SDK build:
Support get_strong and get_weak to create delegates: This update allows a developer to use either get_strong or get_weak instead of a raw this pointer when creating a delegate pointing to a member function.
Add async cancellation callback: The most frequently requested feature for C++/WinRT’s coroutine support has been the addition of a cancellation callback.
Simplify the use of APIs expecting IBuffer parameters: Although most APIs prefer collections or arrays, enough APIs rely on IBuffer that it should be easier to use such APIs from C++. This update provides direct access to the data behind an IBuffer implementation using the same data naming convention used by the C++ standard library containers. This also avoids colliding with metadata names that conventionally begin with an uppercase letter.
Conformance: Improved support for Clang and Visual C++’s stricter conformance modes.
Improved code gen: Various improvements to reduce code size, improve inlining, and optimize factory caching.
Remove unnecessary recursion: When the command line refers to a folder rather than a specific winmd, cppwinrt will no longer search recursively for winmd files. It causes performance problems in the OS build and can lead to usage errors that are hard to diagnose when developers inadvertently cause cppwinrt to consume more winmds than expected. The cppwinrt compiler also now handles duplicates more intelligently, making it more resilient to user error and poorly-formed winmd files.
Declare both WINRT_CanUnloadNow and WINRT_GetActivationFactory in base.h: Callers don’t need to declare them directly. Their signatures have also changed, amounting to a breaking change. The declarations alleviate most of the pain of this change. The change is necessitated by the fact that C++/WinRT no longer depends on the Windows headers and this change removes the dependency on the types from the Windows headers.
Harden smart pointers: The event revokers didn’t revoke when move-assigned a new value. This lead me to take a closer look at the smart pointer classes and I noticed that they were not reliably handling self-assignment. This is rooted in the com_ptr class template that most of the others rely on. I fixed com_ptr and updated the event revokers to handle move semantics correctly to ensure that they revoke upon assignment. The handle class template has also been hardened by the removal of the implicit constructor that made it easy to write incorrect code. This also turned bugs in the OS into compiler errors fixed in this PR.
The updated Preview SDK can be downloaded here.