Comment by andrewg

C++17 does - it's called std::variant.

  std::variant<int, bool, double> options;
  options = true;
  
  bool value = std::get<bool>(options);
  bool has_bool = std::holds_alternative<bool>(options);
  
  // or test which alternative is held
  if (auto i = std::get_if<int>(&options)) {
    // do something with int
  } else if (auto b = std::get_if<bool>(&options)) {
    // do something with bool
  } else {
    // do something with double
  }