std::chrono::choose

enum class choose {
    earliest,
    latest
};

The scoped enumeration choose can be passed to certain member functions of std::chrono::time_zone and std::chrono::zoned_time to control how ambiguous or nonexistent local times should be resolved. Passing choose::earliest causes the earlier time point to be returned, while passing choose::latest causes the later time point to be returned. (For nonexistent local times, these two time points are identical.).

If a choose is not passed and an ambiguous or nonexistent local time is encountered, a std::chrono::ambiguous_local_time or std::chrono::nonexistent_local_time exception (as applicable) will be thrown.