Adapt corelib to use QTimeZone in place of Qt::TimeSpec

This saves (mostly in corelib/time/) some complications that used to
arise from needing different code-paths for different time-specs.

Task-number: QTBUG-108199
Change-Id: I5dbd09859fce7599f1ba761f8a0bfc4633d0bef9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 89 insertions, 71 deletions

diff --git a/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp b/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
index 4c73bb7c9f..b63e506ad2 100644
--- a/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
+++ b/tests/auto/corelib/time/qtimezone/tst_qtimezone.cpp
@@ -4,6 +4,7 @@
 #include <QTest>
 #include <qtimezone.h>
 #include <private/qtimezoneprivate_p.h>
+
 #include <qlocale.h>
 
 #if defined(Q_OS_WIN)
@@ -73,8 +74,8 @@ private:
 void tst_QTimeZone::printTimeZone(const QTimeZone &tz)
 {
     QDateTime now = QDateTime::currentDateTime();
-    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC);
-    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC);
+    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC);
+    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC);
     qDebug() << "";
     qDebug() << "Time Zone               = " << tz;
     qDebug() << "";
@@ -158,9 +159,9 @@ void tst_QTimeZone::createTest()
 
     QCOMPARE(tz.territory(), QLocale::NewZealand);
 
-    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC);
-    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC);
-    QDateTime janPrev = QDateTime(QDate(2011, 1, 1), QTime(0, 0, 0), Qt::UTC);
+    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC);
+    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC);
+    QDateTime janPrev = QDateTime(QDate(2011, 1, 1), QTime(0, 0), QTimeZone::UTC);
 
     QCOMPARE(tz.offsetFromUtc(jan), 13 * 3600);
     QCOMPARE(tz.offsetFromUtc(jun), 12 * 3600);
@@ -180,7 +181,8 @@ void tst_QTimeZone::createTest()
         QTimeZone::OffsetData tran = tz.nextTransition(jan);
         // 2012-04-01 03:00 NZDT, +13 -> +12
         QCOMPARE(tran.atUtc,
-                 QDateTime(QDate(2012, 4, 1), QTime(3, 0), Qt::OffsetFromUTC, 13 * 3600));
+                 QDateTime(QDate(2012, 4, 1), QTime(3, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(13 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 12 * 3600);
         QCOMPARE(tran.standardTimeOffset, 12 * 3600);
         QCOMPARE(tran.daylightTimeOffset, 0);
@@ -188,7 +190,8 @@ void tst_QTimeZone::createTest()
         tran = tz.nextTransition(jun);
         // 2012-09-30 02:00 NZST, +12 -> +13
         QCOMPARE(tran.atUtc,
-                 QDateTime(QDate(2012, 9, 30), QTime(2, 0), Qt::OffsetFromUTC, 12 * 3600));
+                 QDateTime(QDate(2012, 9, 30), QTime(2, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(12 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 13 * 3600);
         QCOMPARE(tran.standardTimeOffset, 12 * 3600);
         QCOMPARE(tran.daylightTimeOffset, 3600);
@@ -196,7 +199,8 @@ void tst_QTimeZone::createTest()
         tran = tz.previousTransition(jan);
         // 2011-09-25 02:00 NZST, +12 -> +13
         QCOMPARE(tran.atUtc,
-                 QDateTime(QDate(2011, 9, 25), QTime(2, 0), Qt::OffsetFromUTC, 12 * 3600));
+                 QDateTime(QDate(2011, 9, 25), QTime(2, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(12 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 13 * 3600);
         QCOMPARE(tran.standardTimeOffset, 12 * 3600);
         QCOMPARE(tran.daylightTimeOffset, 3600);
@@ -204,17 +208,20 @@ void tst_QTimeZone::createTest()
         tran = tz.previousTransition(jun);
         // 2012-04-01 03:00 NZDT, +13 -> +12 (again)
         QCOMPARE(tran.atUtc,
-                 QDateTime(QDate(2012, 4, 1), QTime(3, 0), Qt::OffsetFromUTC, 13 * 3600));
+                 QDateTime(QDate(2012, 4, 1), QTime(3, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(13 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 12 * 3600);
         QCOMPARE(tran.standardTimeOffset, 12 * 3600);
         QCOMPARE(tran.daylightTimeOffset, 0);
 
         QTimeZone::OffsetDataList expected;
         // Reuse 2012's fall-back data for 2011-04-03:
-        tran.atUtc = QDateTime(QDate(2011, 4, 3), QTime(3, 0), Qt::OffsetFromUTC, 13 * 3600);
+        tran.atUtc = QDateTime(QDate(2011, 4, 3), QTime(3, 0),
+                               QTimeZone::fromSecondsAheadOfUtc(13 * 3600));
         expected << tran;
         // 2011's spring-forward:
-        tran.atUtc = QDateTime(QDate(2011, 9, 25), QTime(2, 0), Qt::OffsetFromUTC, 12 * 3600);
+        tran.atUtc = QDateTime(QDate(2011, 9, 25), QTime(2, 0),
+                               QTimeZone::fromSecondsAheadOfUtc(12 * 3600));
         tran.offsetFromUtc = 13 * 3600;
         tran.daylightTimeOffset = 3600;
         expected << tran;
@@ -256,9 +263,9 @@ void tst_QTimeZone::nullTest()
     QCOMPARE(nullTz1.territory(), QLocale::AnyTerritory);
     QCOMPARE(nullTz1.comment(), QString());
 
-    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC);
-    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC);
-    QDateTime janPrev = QDateTime(QDate(2011, 1, 1), QTime(0, 0, 0), Qt::UTC);
+    QDateTime jan = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC);
+    QDateTime jun = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC);
+    QDateTime janPrev = QDateTime(QDate(2011, 1, 1), QTime(0, 0), QTimeZone::UTC);
 
     QCOMPARE(nullTz1.abbreviation(jan), QString());
     QCOMPARE(nullTz1.displayName(jan), QString());
@@ -514,7 +521,7 @@ void tst_QTimeZone::systemZone()
         QDate(2038, 1, 20) // First day after 32-bit time_t's range
     };
     for (const auto &date : dates)
-        QCOMPARE(date.startOfDay(Qt::LocalTime), date.startOfDay(zone));
+        QCOMPARE(date.startOfDay(QTimeZone::LocalTime), date.startOfDay(zone));
 
 #if __cpp_lib_chrono >= 201907L
     const std::chrono::time_zone *currentTimeZone = std::chrono::current_zone();
@@ -636,7 +643,7 @@ void tst_QTimeZone::utcOffsetId()
     QTimeZone zone(id);
     QCOMPARE(zone.isValid(), valid);
     if (valid) {
-        QDateTime epoch(QDate(1970, 1, 1), QTime(0, 0, 0), Qt::UTC);
+        QDateTime epoch(QDate(1970, 1, 1), QTime(0, 0), QTimeZone::UTC);
         QFETCH(int, offset);
         QCOMPARE(zone.offsetFromUtc(epoch), offset);
         QVERIFY(!zone.hasDaylightTime());
@@ -669,15 +676,15 @@ void tst_QTimeZone::specificTransition_data()
         QTest::newRow("Moscow/2014") // From original bug-report
             << QByteArray("Europe/Moscow")
             << QDate(2011, 4, 1) << QDate(2021, 12, 31) << 1
-            << QDateTime(QDate(2014, 10, 26), QTime(2, 0, 0),
-                         Qt::OffsetFromUTC, 4 * 3600).toUTC()
+            << QDateTime(QDate(2014, 10, 26), QTime(2, 0),
+                         QTimeZone::fromSecondsAheadOfUtc(4 * 3600)).toUTC()
             << 3 * 3600 << 3 * 3600 << 0;
     }
     QTest::newRow("Moscow/2011") // Transition on 2011-03-27
         << QByteArray("Europe/Moscow")
         << QDate(2010, 11, 1) << QDate(2014, 10, 25) << 1
-        << QDateTime(QDate(2011, 3, 27), QTime(2, 0, 0),
-                     Qt::OffsetFromUTC, 3 * 3600).toUTC()
+        << QDateTime(QDate(2011, 3, 27), QTime(2, 0),
+                     QTimeZone::fromSecondsAheadOfUtc(3 * 3600)).toUTC()
         << 4 * 3600 << 4 * 3600 << 0;
 }
 
@@ -849,12 +856,13 @@ void tst_QTimeZone::availableTimeZoneIds()
 
 void tst_QTimeZone::stressTest()
 {
+    const auto UTC = QTimeZone::UTC;
     const QList<QByteArray> idList = QTimeZone::availableTimeZoneIds();
     for (const QByteArray &id : idList) {
         QTimeZone testZone = QTimeZone(id);
         QCOMPARE(testZone.isValid(), true);
         QCOMPARE(testZone.id(), id);
-        QDateTime testDate = QDateTime(QDate(2015, 1, 1), QTime(0, 0, 0), Qt::UTC);
+        QDateTime testDate = QDateTime(QDate(2015, 1, 1), QTime(0, 0), UTC);
         testZone.territory();
         testZone.comment();
         testZone.displayName(testDate);
@@ -871,10 +879,10 @@ void tst_QTimeZone::stressTest()
         testZone.nextTransition(testDate);
         testZone.previousTransition(testDate);
         // Dates known to be outside possible tz file pre-calculated rules range
-        QDateTime lowDate1 = QDateTime(QDate(1800, 1, 1), QTime(0, 0, 0), Qt::UTC);
-        QDateTime lowDate2 = QDateTime(QDate(1800, 6, 1), QTime(0, 0, 0), Qt::UTC);
-        QDateTime highDate1 = QDateTime(QDate(2200, 1, 1), QTime(0, 0, 0), Qt::UTC);
-        QDateTime highDate2 = QDateTime(QDate(2200, 6, 1), QTime(0, 0, 0), Qt::UTC);
+        QDateTime lowDate1 = QDateTime(QDate(1800, 1, 1), QTime(0, 0), UTC);
+        QDateTime lowDate2 = QDateTime(QDate(1800, 6, 1), QTime(0, 0), UTC);
+        QDateTime highDate1 = QDateTime(QDate(2200, 1, 1), QTime(0, 0), UTC);
+        QDateTime highDate2 = QDateTime(QDate(2200, 6, 1), QTime(0, 0), UTC);
         testZone.nextTransition(lowDate1);
         testZone.nextTransition(lowDate2);
         testZone.previousTransition(lowDate2);
@@ -1196,8 +1204,8 @@ void tst_QTimeZone::icuTest()
 {
 #if defined(QT_BUILD_INTERNAL) && QT_CONFIG(icu)
     // Known datetimes
-    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
+    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
+    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
 
     // Test default constructor
     QIcuTimeZonePrivate tzpd;
@@ -1241,9 +1249,10 @@ void tst_QTimeZone::icuTest()
 void tst_QTimeZone::tzTest()
 {
 #if defined QT_BUILD_INTERNAL && defined Q_OS_UNIX && !defined Q_OS_DARWIN && !defined Q_OS_ANDROID
+    const auto UTC = QTimeZone::UTC;
     // Known datetimes
-    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
+    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0), UTC).toMSecsSinceEpoch();
+    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0), UTC).toMSecsSinceEpoch();
 
     // Test default constructor
     QTzTimeZonePrivate tzpd;
@@ -1276,8 +1285,8 @@ void tst_QTimeZone::tzTest()
     // It shouldn't have any transitions. QTimeZone::hasTransitions() only says
     // whether the backend supports them, so ask for transitions in a wide
     // enough interval that one would show up, if there are any:
-    QVERIFY(permaDst.transitions(QDate(2015, 1, 1).startOfDay(Qt::UTC).toMSecsSinceEpoch(),
-                                 QDate(2020, 1, 1).startOfDay(Qt::UTC).toMSecsSinceEpoch()
+    QVERIFY(permaDst.transitions(QDate(2015, 1, 1).startOfDay(UTC).toMSecsSinceEpoch(),
+                                 QDate(2020, 1, 1).startOfDay(UTC).toMSecsSinceEpoch()
                                 ).isEmpty());
 
     QTimeZone tzBrazil("BRT+3"); // parts of Northern Brazil, as a POSIX rule
@@ -1348,14 +1357,16 @@ void tst_QTimeZone::tzTest()
     }
 
     dat = tzp.nextTransition(ancient);
-    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, Qt::OffsetFromUTC, 3600),
-             QDateTime(QDate(1893, 4, 1), QTime(0, 6, 32), Qt::OffsetFromUTC, 3600));
+    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch,
+                                            QTimeZone::fromSecondsAheadOfUtc(3600)),
+             QDateTime(QDate(1893, 4, 1), QTime(0, 6, 32),
+                       QTimeZone::fromSecondsAheadOfUtc(3600)));
     QCOMPARE(dat.standardTimeOffset, 3600);
     QCOMPARE(dat.daylightTimeOffset, 0);
 
     // Date-times late enough to exercise POSIX rules:
-    qint64 stdHi = QDate(2100, 1, 1).startOfDay(Qt::UTC).toMSecsSinceEpoch();
-    qint64 dstHi = QDate(2100, 6, 1).startOfDay(Qt::UTC).toMSecsSinceEpoch();
+    qint64 stdHi = QDate(2100, 1, 1).startOfDay(UTC).toMSecsSinceEpoch();
+    qint64 dstHi = QDate(2100, 6, 1).startOfDay(UTC).toMSecsSinceEpoch();
     // Relevant last Sundays in October and March:
     QCOMPARE(Qt::DayOfWeek(QDate(2099, 10, 25).dayOfWeek()), Qt::Sunday);
     QCOMPARE(Qt::DayOfWeek(QDate(2100, 3, 28).dayOfWeek()), Qt::Sunday);
@@ -1375,32 +1386,33 @@ void tst_QTimeZone::tzTest()
 
     dat = tzp.previousTransition(stdHi);
     QCOMPARE(dat.abbreviation, QStringLiteral("CET"));
-    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, Qt::UTC),
-             QDateTime(QDate(2099, 10, 25), QTime(3, 0), Qt::OffsetFromUTC, 7200));
+    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, UTC),
+             QDateTime(QDate(2099, 10, 25), QTime(3, 0), QTimeZone::fromSecondsAheadOfUtc(7200)));
     QCOMPARE(dat.offsetFromUtc, 3600);
     QCOMPARE(dat.standardTimeOffset, 3600);
     QCOMPARE(dat.daylightTimeOffset, 0);
 
     dat = tzp.previousTransition(dstHi);
     QCOMPARE(dat.abbreviation, QStringLiteral("CEST"));
-    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, Qt::UTC),
-             QDateTime(QDate(2100, 3, 28), QTime(2, 0), Qt::OffsetFromUTC, 3600));
+    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, UTC),
+             QDateTime(QDate(2100, 3, 28), QTime(2, 0), QTimeZone::fromSecondsAheadOfUtc(3600)));
     QCOMPARE(dat.offsetFromUtc, 7200);
     QCOMPARE(dat.standardTimeOffset, 3600);
     QCOMPARE(dat.daylightTimeOffset, 3600);
 
     dat = tzp.nextTransition(stdHi);
     QCOMPARE(dat.abbreviation, QStringLiteral("CEST"));
-    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, Qt::UTC),
-             QDateTime(QDate(2100, 3, 28), QTime(2, 0), Qt::OffsetFromUTC, 3600));
+    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, UTC),
+             QDateTime(QDate(2100, 3, 28), QTime(2, 0), QTimeZone::fromSecondsAheadOfUtc(3600)));
     QCOMPARE(dat.offsetFromUtc, 7200);
     QCOMPARE(dat.standardTimeOffset, 3600);
     QCOMPARE(dat.daylightTimeOffset, 3600);
 
     dat = tzp.nextTransition(dstHi);
     QCOMPARE(dat.abbreviation, QStringLiteral("CET"));
-    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch, Qt::OffsetFromUTC, 3600),
-             QDateTime(QDate(2100, 10, 31), QTime(3, 0), Qt::OffsetFromUTC, 7200));
+    QCOMPARE(QDateTime::fromMSecsSinceEpoch(dat.atMSecsSinceEpoch,
+                                            QTimeZone::fromSecondsAheadOfUtc(3600)),
+             QDateTime(QDate(2100, 10, 31), QTime(3, 0), QTimeZone::fromSecondsAheadOfUtc(7200)));
     QCOMPARE(dat.offsetFromUtc, 3600);
     QCOMPARE(dat.standardTimeOffset, 3600);
     QCOMPARE(dat.daylightTimeOffset, 0);
@@ -1429,7 +1441,7 @@ void tst_QTimeZone::tzTest()
         QCOMPARE(tzBarnaul.data(std).abbreviation, QString("+07"));
 
         // first full day of the new rule (tzdata2016b)
-        QDateTime dt(QDate(2016, 3, 28), QTime(0, 0, 0), Qt::UTC);
+        QDateTime dt(QDate(2016, 3, 28), QTime(0, 0), UTC);
         QCOMPARE(tzBarnaul.data(dt.toMSecsSinceEpoch()).abbreviation, QString("+07"));
     }
 #endif // QT_BUILD_INTERNAL && Q_OS_UNIX && !Q_OS_DARWIN
@@ -1439,8 +1451,8 @@ void tst_QTimeZone::macTest()
 {
 #if defined(QT_BUILD_INTERNAL) && defined(Q_OS_DARWIN)
     // Known datetimes
-    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
+    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
+    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
 
     // Test default constructor
     QMacTimeZonePrivate tzpd;
@@ -1495,8 +1507,8 @@ void tst_QTimeZone::winTest()
 {
 #if defined(QT_BUILD_INTERNAL) && defined(USING_WIN_TZ)
     // Known datetimes
-    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
+    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
+    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0), QTimeZone::UTC).toMSecsSinceEpoch();
 
     // Test default constructor
     QWinTimeZonePrivate tzpd;
@@ -1598,9 +1610,11 @@ void tst_QTimeZone::localeSpecificDisplayName()
 void tst_QTimeZone::testCetPrivate(const QTimeZonePrivate &tzp)
 {
     // Known datetimes
-    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
-    qint64 prev = QDateTime(QDate(2011, 1, 1), QTime(0, 0, 0), Qt::UTC).toMSecsSinceEpoch();
+    const auto UTC = QTimeZone::UTC;
+    const auto eastOneHour = QTimeZone::fromSecondsAheadOfUtc(3600);
+    qint64 std = QDateTime(QDate(2012, 1, 1), QTime(0, 0), UTC).toMSecsSinceEpoch();
+    qint64 dst = QDateTime(QDate(2012, 6, 1), QTime(0, 0), UTC).toMSecsSinceEpoch();
+    qint64 prev = QDateTime(QDate(2011, 1, 1), QTime(0, 0), UTC).toMSecsSinceEpoch();
 
     QCOMPARE(tzp.offsetFromUtc(std), 3600);
     QCOMPARE(tzp.offsetFromUtc(dst), 7200);
@@ -1633,32 +1647,34 @@ void tst_QTimeZone::testCetPrivate(const QTimeZonePrivate &tzp)
     if (tzp.hasTransitions()) {
         QTimeZonePrivate::Data tran = tzp.nextTransition(std);
         // 2012-03-25 02:00 CET, +1 -> +2
-        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC),
-                 QDateTime(QDate(2012, 3, 25), QTime(2, 0), Qt::OffsetFromUTC, 3600));
+        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC),
+                 QDateTime(QDate(2012, 3, 25), QTime(2, 0), eastOneHour));
         QCOMPARE(tran.offsetFromUtc, 7200);
         QCOMPARE(tran.standardTimeOffset, 3600);
         QCOMPARE(tran.daylightTimeOffset, 3600);
 
         tran = tzp.nextTransition(dst);
         // 2012-10-28 03:00 CEST, +2 -> +1
-        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC),
-                 QDateTime(QDate(2012, 10, 28), QTime(3, 0), Qt::OffsetFromUTC, 2 * 3600));
+        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC),
+                 QDateTime(QDate(2012, 10, 28), QTime(3, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(2 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 3600);
         QCOMPARE(tran.standardTimeOffset, 3600);
         QCOMPARE(tran.daylightTimeOffset, 0);
 
         tran = tzp.previousTransition(std);
         // 2011-10-30 03:00 CEST, +2 -> +1
-        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC),
-                 QDateTime(QDate(2011, 10, 30), QTime(3, 0), Qt::OffsetFromUTC, 2 * 3600));
+        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC),
+                 QDateTime(QDate(2011, 10, 30), QTime(3, 0),
+                           QTimeZone::fromSecondsAheadOfUtc(2 * 3600)));
         QCOMPARE(tran.offsetFromUtc, 3600);
         QCOMPARE(tran.standardTimeOffset, 3600);
         QCOMPARE(tran.daylightTimeOffset, 0);
 
         tran = tzp.previousTransition(dst);
         // 2012-03-25 02:00 CET, +1 -> +2 (again)
-        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC),
-                 QDateTime(QDate(2012, 3, 25), QTime(2, 0), Qt::OffsetFromUTC, 3600));
+        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC),
+                 QDateTime(QDate(2012, 3, 25), QTime(2, 0), eastOneHour));
         QCOMPARE(tran.offsetFromUtc, 7200);
         QCOMPARE(tran.standardTimeOffset, 3600);
         QCOMPARE(tran.daylightTimeOffset, 3600);
@@ -1666,14 +1682,15 @@ void tst_QTimeZone::testCetPrivate(const QTimeZonePrivate &tzp)
         QTimeZonePrivate::DataList expected;
         // 2011-03-27 02:00 CET, +1 -> +2
         tran.atMSecsSinceEpoch = QDateTime(QDate(2011, 3, 27), QTime(2, 0),
-                                           Qt::OffsetFromUTC, 3600).toMSecsSinceEpoch();
+                                           eastOneHour).toMSecsSinceEpoch();
         tran.offsetFromUtc = 7200;
         tran.standardTimeOffset = 3600;
         tran.daylightTimeOffset = 3600;
         expected << tran;
         // 2011-10-30 03:00 CEST, +2 -> +1
         tran.atMSecsSinceEpoch = QDateTime(QDate(2011, 10, 30), QTime(3, 0),
-                                           Qt::OffsetFromUTC, 2 * 3600).toMSecsSinceEpoch();
+                                           QTimeZone::fromSecondsAheadOfUtc(2 * 3600)
+                                           ).toMSecsSinceEpoch();
         tran.offsetFromUtc = 3600;
         tran.standardTimeOffset = 3600;
         tran.daylightTimeOffset = 0;
@@ -1681,10 +1698,8 @@ void tst_QTimeZone::testCetPrivate(const QTimeZonePrivate &tzp)
         QTimeZonePrivate::DataList result = tzp.transitions(prev, std);
         QCOMPARE(result.size(), expected.size());
         for (int i = 0; i < expected.size(); ++i) {
-            QCOMPARE(QDateTime::fromMSecsSinceEpoch(result.at(i).atMSecsSinceEpoch,
-                                                    Qt::OffsetFromUTC, 3600),
-                     QDateTime::fromMSecsSinceEpoch(expected.at(i).atMSecsSinceEpoch,
-                                                    Qt::OffsetFromUTC, 3600));
+            QCOMPARE(QDateTime::fromMSecsSinceEpoch(result.at(i).atMSecsSinceEpoch, eastOneHour),
+                     QDateTime::fromMSecsSinceEpoch(expected.at(i).atMSecsSinceEpoch, eastOneHour));
             QCOMPARE(result.at(i).offsetFromUtc, expected.at(i).offsetFromUtc);
             QCOMPARE(result.at(i).standardTimeOffset, expected.at(i).standardTimeOffset);
             QCOMPARE(result.at(i).daylightTimeOffset, expected.at(i).daylightTimeOffset);
@@ -1698,10 +1713,13 @@ void tst_QTimeZone::testEpochTranPrivate(const QTimeZonePrivate &tzp)
     if (!tzp.hasTransitions())
         return; // test only viable for transitions
 
+    const auto UTC = QTimeZone::UTC;
+    const auto hour = std::chrono::hours{1};
     QTimeZonePrivate::Data tran = tzp.nextTransition(0); // i.e. first after epoch
     // 1970-04-26 02:00 EST, -5 -> -4
-    const QDateTime after = QDateTime(QDate(1970, 4, 26), QTime(2, 0), Qt::OffsetFromUTC, -5 * 3600);
-    const QDateTime found = QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC);
+    const QDateTime after = QDateTime(QDate(1970, 4, 26), QTime(2, 0),
+                                      QTimeZone::fromDurationAheadOfUtc(-5 * hour));
+    const QDateTime found = QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC);
 #ifdef USING_WIN_TZ // MS gets the date wrong: 5th April instead of 26th.
     QCOMPARE(found.toOffsetFromUtc(-5 * 3600).time(), after.time());
 #else
@@ -1712,16 +1730,16 @@ void tst_QTimeZone::testEpochTranPrivate(const QTimeZonePrivate &tzp)
     QCOMPARE(tran.daylightTimeOffset, 3600);
 
     // Pre-epoch time-zones might not be supported at all:
-    tran = tzp.nextTransition(QDateTime(QDate(1601, 1, 1), QTime(0, 0),
-                                        Qt::UTC).toMSecsSinceEpoch());
+    tran = tzp.nextTransition(QDateTime(QDate(1601, 1, 1), QTime(0, 0), UTC).toMSecsSinceEpoch());
     if (tran.atMSecsSinceEpoch != QTimeZonePrivate::invalidMSecs()
         // Toronto *did* have a transition before 1970 (DST since 1918):
         && tran.atMSecsSinceEpoch < 0) {
         // ... but, if they are, we should be able to search back to them:
         tran = tzp.previousTransition(0); // i.e. last before epoch
         // 1969-10-26 02:00 EDT, -4 -> -5
-        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, Qt::UTC),
-                 QDateTime(QDate(1969, 10, 26), QTime(2, 0), Qt::OffsetFromUTC, -4 * 3600));
+        QCOMPARE(QDateTime::fromMSecsSinceEpoch(tran.atMSecsSinceEpoch, UTC),
+                 QDateTime(QDate(1969, 10, 26), QTime(2, 0),
+                           QTimeZone::fromDurationAheadOfUtc(-4 * hour)));
         QCOMPARE(tran.offsetFromUtc, -5 * 3600);
         QCOMPARE(tran.standardTimeOffset, -5 * 3600);
         QCOMPARE(tran.daylightTimeOffset, 0);