在课程结束时boost :: shared_ptr错误

class SomeData{};
typedef boost::shared_ptr<SomeData> data_ptr;

class ABC {
public:   ABC(){}

          ~ABC(){cached_ptr.reset(); }

          data_ptr get_ptr() {data_ptr x; return x;} // it does work and returns a data_ptr

          bool someWork(data_ptr& passed_ptr) {
            if(cached_ptr == NULL) {
              cached_ptr = get_ptr();
              passed_ptr.reset(new SomeData(*cached_ptr));
            }
            return true;
          }

          data_ptr otherWork() {
            if(cached_ptr == NULL) { 
                cached_ptr = get_ptr();
                data_ptr local_ptr = boost::make_shared<SomeData>(*cached_ptr);
            }
            return data_ptr;   // after some more work
         }

private:  data_ptr cached_ptr;   // class member
};
class SomeData{};
typedef boost::shared_ptr<Som