関連ワード:  c++ unique pointer to shared pointer    c++ unique_ptr to shared_ptr    c++ unique pointer vs shared pointer    c++ convert unique_ptr to shared_ptr    c++ assign unique_ptr to shared_ptr    c++ pass unique_ptr to shared_ptr    c++ copy unique_ptr to shared_ptr    c++ pointer to shared pointer    c++ unique_ptr vs shared_ptr    c++ unique_ptr vs shared_ptr performance