Средства и методы разработки

https://en.cppreference.com/w/cpp/types/underlying_type

https://onlinegdb.com/PCCm8X1Pg

template<typename E>
  E operator|(E lhs,E rhs){
    typedef typename
      std::underlying_type<E>::type underlying;
    return static_cast<E>(
      static_cast<underlying>(lhs) 
    | static_cast<underlying>(rhs));
  }
  
enum FLG  {F0= (1u << 0) , F1= (1u << 1)};
int main()
{
    auto f =  F0 | F1;
    std::cout << static_cast<int>(f) << std::endl;
}