bsl::weak_ptr::operator=

Make this weak pointer refer to the same object (if any) as the specified rhs weak pointer. If rhs is not a reference to this weak pointer, decrement the number of weak references to the object this weak pointer managed (if any), and reset rhs to an empty state. Return a reference providing modifiable access to this weak pointer. Note that if rhs is in an empty state, this weak pointer will be set to an empty state.