std::sort(vec.begin(), vec.end(), 
              [] (const auto& lhs, const auto& rhs) { 
      return lhs.whatever < rhs.whatever;
    });

    auto sort_by_whatever = [] (const auto& lhs, const auto& rhs) { 
      return lhs.whatever < rhs.whatever;
    };
    std::sort(vec.begin(), vec.end(), sort_by_whatever);