std::chrono::zoned_time::operator sys_time(C++20)

#include <cassert>
#include <chrono>

namespace chrono = std::chrono;
using namespace std::chrono_literals;

int main()
{
  auto now = chrono::system_clock::now();
  chrono::local_time local_now{now.time_since_epoch()};

  chrono::zoned_time zt1{"Asia/Tokyo", now};
  assert(zt1 == now);

  chrono::sys_time sys_now = zt1;
  assert(sys_now == now);

  chrono::zoned_time zt2{"Asia/Tokyo", local_now};
  assert(zt2 == now);
}