private static function calDaysInMonthFrench($year, $month)
    {
        if ($month == 13 && $year == 14 && self::shouldEmulateBug67976()) {
            return -2380948;
        } elseif ($year > 14) {
            $error_msg = PHP_VERSION_ID < 70200 ? 'invalid date.' : 'invalid date';

            return trigger_error($error_msg, E_USER_WARNING);
        } else {
            return self::calDaysInMonthCalendar(self::$french_calendar, $year, $month);
        }
    }