Function ref_cast

src/common/ref.h:13–15

template<typename T> using cref_t = boost::intrusive_ptr<const T>;
template<class T, class U>
ref_t<T> ref_cast(const ref_t<U>& r) noexcept {
  return static_cast<T*>(r.get());
}
template<class T, class U>
ref_t<T> ref_cast(ref_t<U>&& r) noexcept {
  return {static_cast<T*>(r.detach()), false};