27 Time library [time]

27.11 Time zones [time.zone]

27.11.3 Exception classes [time.zone.exception]

27.11.3.1 Class nonexistent_­local_­time [time.zone.exception.nonexist]

namespace std::chrono {
  class nonexistent_local_time : public runtime_error {
  public:
    template<class Duration>
      nonexistent_local_time(const local_time<Duration>& tp, const local_info& i);
  };
}
1
#
nonexistent_­local_­time is thrown when an attempt is made to convert a non-existent local_­time to a sys_­time without specifying choose​::​earliest or choose​::​latest.
🔗
template<class Duration> nonexistent_local_time(const local_time<Duration>& tp, const local_info& i);
2
#
Preconditions: i.result == local_­info​::​nonexistent is true.
3
#
Effects: Initializes the base class with a sequence of char equivalent to that produced by os.str() initialized as shown below: 
ostringstream os;
os << tp << " is in a gap between\n"
   << local_seconds{i.first.end.time_since_epoch()} + i.first.offset << ' '
   << i.first.abbrev << " and\n"
   << local_seconds{i.second.begin.time_since_epoch()} + i.second.offset << ' '
   << i.second.abbrev
   << " which are both equivalent to\n"
   << i.first.end << " UTC";
4
#
[Example
: 
#include <chrono>
#include <iostream>

int main() {
  using namespace std::chrono;
  try {
    auto zt = zoned_time{"America/New_York",
                         local_days{Sunday[2]/March/2016} + 2h + 30min};
  } catch (const nonexistent_local_time& e) {
    std::cout << e.what() << '\n';
  }
}
Produces the output:
2016-03-13 02:30:00 is in a gap between
2016-03-13 02:00:00 EST and
2016-03-13 03:00:00 EDT which are both equivalent to
2016-03-13 07:00:00 UTC
— end example
]