Mac: Wrong QDate string conversion with Qt::SystemLocaleLongDate on dates prior to 1893-04-02

#include <QDebug>
#include <QDate>

#include <CoreFoundation/CoreFoundation.h>
extern "C" { void NSLog(CFStringRef format, ...); }

void dump(const QDate &d)
{
  qDebug() << "Qt version" << QT_VERSION_STR
           << "qDebug" << d
           << ".toString()" << d.toString()
           << ".toString(Qt::SystemLocaleLongDate)" << d.toString(Qt::SystemLocaleLongDate);
}

int main(int argc, char *argv[])
{
  // good
  dump(QDate(1893, 04, 02));
  // bad
  dump(QDate(1893, 04, 01));

  // source of bug can be found here (macDateToString from qlocale_mac.mm)
  bool short_format = true;
  CFGregorianDate macGDate;
  macGDate.year = 1893;
  macGDate.month = 4;
  macGDate.day = 1;
  macGDate.hour = 0;
  macGDate.minute = 0;
  macGDate.second = 0.0;
  CFDateRef myDate = CFDateCreate(0, CFGregorianDateGetAbsoluteTime(macGDate, CFTimeZoneCopyDefault()/*null fixes the problem*/));
  CFLocaleRef mylocale = CFLocaleCopyCurrent();
  CFDateFormatterStyle style = short_format ? kCFDateFormatterShortStyle : kCFDateFormatterLongStyle;
  CFDateFormatterRef myFormatter = CFDateFormatterCreate(kCFAllocatorDefault,
                                                         mylocale, style,
                                                         kCFDateFormatterNoStyle);

  NSLog(CFSTR("CF conversion: %@"), CFDateFormatterCreateStringWithDate(0, myFormatter, myDate));

  return 0;
}

Qt version 5.8.0 qDebug QDate("1893-04-02") .toString() "So. Apr. 2 1893" .toString(Qt::SystemLocaleLongDate) "2. April 1893"
Qt version 5.8.0 qDebug QDate("1893-04-01") .toString() "Sa. Apr. 1 1893" .toString(Qt::SystemLocaleLongDate) "31. März 1893"
2016-07-27 14:42:05.917 datebug2[19841:11691404] CF conversion: 31.03.93

   QDateTime dt;
  dt.setDate(QDate(782, 11, 12));
  qDebug() << dt << QLocale().toString(dt, QLocale::ShortFormat) << QLocale().toString(dt.date(), QLocale::ShortFormat);

QDateTime(0782-11-12 00:00:00.000 EET Qt::LocalTime) "12.11.0782 00:00" "8.11.782"