Extended Description

This:

static_assert(__reference_binds_to_temporary(int&&, int));

Fails, the implementation doesn't consider this to be a reference binding to a temporary (the implementation is in terms of isDirectReferenceBinding).

While this particular case isn't important for std::tuple (where we'll have already materialized the temporary on the constructor boundary, so the right-hand side would be int&& already), it is important for the INVOKE<R> machinery -- where we might want to reject std::function<int&&()>([]{ return 42; }).