Bug: In some situations, calling get_weak() may over-release the "outer" object about cppwinrt HOT 1 OPEN

Spent a bit of time debugging this on my end. A few thoughts before I get back to work and forget all about this. 😉

• C++/WinRT support for weak references is limited to non-composable or at least non-open composable hierarchies. That's because it's implemented by swapping out the ref count on the object while open composable types delegate ref counting to the outer/derived object and thus there's really two ref counts at play and that's not supported by the C++/WinRT weak reference implementation.
• C++/WinRT support for open/binary composable hierarchies is limited to Xaml. Nothing else has ever been tested nor is it recommended.
• To the best of my knowledge, the base composable type in Xaml has always been implemented in something other than C++/WinRT. Its that base composable type(s) that must implement weak reference support. Derived types cannot do it - they simply delegate to the base.
• You may want to confirm that a derived type in the binary hierarchy isn't accidentally responding to queries for IWeakReferenceSource. That would be a big problem.
• You can instruct C++/WinRT not to implement weak reference support for a particular implementation by using the no_weak_ref marker type.

Here's a more minimal example of open composability in C++/WinRT for debugging purposes only:

https://gist.github.com/kennykerr/2a5dd202274f49031adbd50e02d8b4d0

from cppwinrt.