Construct a copy of a different cancellation slot wrapper type, but specify a different cancellation slot.

template<
    typename U,
    typename OtherCancellationSlot>
cancellation_slot_binder(
    const cancellation_slot_type & s,
    const cancellation_slot_binder< U, OtherCancellationSlot > & other);

This constructor is only valid if the type T is constructible from type U.