Restore previous QDateTime behavior in DST gap

Historic QDateTime behavior when being asked to create a
QDateTime in the DST gap was to interpret the given date
as if it was in the time before that gap, mapping it to a point
in time after the gap. This has changed with
a04411119ead3d4473e4f0ac4bceedc585977b2f .
Since then, the given date is interpreted as if it was in the
time after the gap, thus being mapped to a point in time
before the gap.
This patch restores the historic behavior.
This was not caught by Coin because machines ran in timezone
"Atlantic/Reykjavik" which does not have DST since 1967.
This patch changes tests to always run in "Europe/Oslo".
Driveby: Test function "findSpring" did some operations in
local time, even though being asked to work in a specific
time zone. Fixed that.

Fixes: QTBUG-86960
Fixes: QTBUG-89208
Pick-to: 6.0 5.15
Change-Id: Iecce5898bf9711a10e7dfc0a25e4bbeaed1c8ade
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/auto/widgets/widgets/qdatetimeedit/tst_qdatetimeedit.cpp b/tests/auto/widgets/widgets/qdatetimeedit/tst_qdatetimeedit.cpp
index b7ae7df5ed..05124d1ad6 100644
--- a/tests/auto/widgets/widgets/qdatetimeedit/tst_qdatetimeedit.cpp
+++ b/tests/auto/widgets/widgets/qdatetimeedit/tst_qdatetimeedit.cpp
@@ -4622,7 +4622,7 @@ static QDateTime findSpring(int year, const QTimeZone &timeZone)
         return QDateTime();
 
     // Southern hemisphere spring is after midsummer
-    const QDateTime midSummer = QDate(year, 6, 21).startOfDay();
+    const QDateTime midSummer = QDate(year, 6, 21).startOfDay(timeZone);
     const QTimeZone::OffsetData transition =
         midSummer.isDaylightTime() ? timeZone.previousTransition(midSummer)
                                    : timeZone.nextTransition(midSummer);
@@ -4744,7 +4744,7 @@ void tst_QDateTimeEdit::stepIntoDSTGap_data()
     QTest::addColumn<int>("steps");
     QTest::addColumn<QDateTime>("end");
 
-    const QTimeZone timeZone = QTimeZone::systemTimeZone();
+    const QTimeZone timeZone = QTimeZone("Europe/Oslo");
     if (!timeZone.hasDaylightTime())
         QSKIP("This test needs to run in a timezone that observes DST!");