Revert QDateTime serialisation to pre-Qt 5 behaviour.

In Qt 5, I managed to break the guarantee that a deserialised local
datetime is the same time of day (potentially different UTC time),
regardless of which timezone it was serialised in. This happened after
I fixed QTBUG-4057 with If650e7960dca7b6ab44b8233410a6369c41df73a,
which serialised datetimes as UTC.

This patch reverts QDateTime serialisation to pre-Qt 5 behaviour to
restore the guarantee and consequently re-opens QTBUG-4057.

Change-Id: Iea877f7ed886f530b928067789b53534e89fe8cb
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 19 insertions, 4 deletions

diff --git a/tests/auto/corelib/io/qdatastream/tst_qdatastream.cpp b/tests/auto/corelib/io/qdatastream/tst_qdatastream.cpp
index d7fc76d980..3607467ff9 100644
--- a/tests/auto/corelib/io/qdatastream/tst_qdatastream.cpp
+++ b/tests/auto/corelib/io/qdatastream/tst_qdatastream.cpp
@@ -268,7 +268,8 @@ static int NColorRoles[] = {
     QPalette::ToolTipText + 1,     // Qt_4_5
     QPalette::ToolTipText + 1,     // Qt_4_6
     QPalette::ToolTipText + 1,     // Qt_5_0
-    0                              // add the correct value for Qt_5_1 here later
+    QPalette::ToolTipText + 1,     // Qt_5_1
+    0                              // add the correct value for Qt_5_2 here later
 };
 
 // Testing get/set functions
diff --git a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
index 6cfcf74069..0ec3f64020 100644
--- a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
@@ -1398,13 +1398,19 @@ void tst_QDateTime::operator_insert_extract()
     {
         QDataStream dataStream(&byteArray, QIODevice::WriteOnly);
         dataStream.setVersion(dataStreamVersion);
-        if (dataStreamVersion >= QDataStream::Qt_5_0) {
+        if (dataStreamVersion == QDataStream::Qt_5_0) {
             // Qt 5 serialises as UTC and converts back to the stored timeSpec when
             // deserialising; we don't need to do it ourselves...
             dataStream << dateTime << dateTime;
         } else {
-            // ... but lower versions don't, so we have to here.
+            // ... but other versions don't, so we have to here.
             dataStream << dateTimeAsUTC << dateTimeAsUTC;
+            // We'll also make sure that a deserialised local datetime is the same
+            // time of day (potentially different UTC time), regardless of which
+            // timezone it was serialised in. E.g.: Tue Aug 14 08:00:00 2012
+            // serialised in WST should be deserialised as Tue Aug 14 08:00:00 2012
+            // HST.
+            dataStream << dateTime;
         }
     }
 
@@ -1420,7 +1426,7 @@ void tst_QDateTime::operator_insert_extract()
         QDateTime deserialised;
         dataStream >> deserialised;
 
-        if (dataStreamVersion >= QDataStream::Qt_5_0) {
+        if (dataStreamVersion == QDataStream::Qt_5_0) {
             // Ensure local time is still correct. Again, Qt 5 handles the timeSpec
             // conversion (in this case, UTC => LocalTime) for us when deserialising.
             QCOMPARE(deserialised, expectedLocalTime);
@@ -1453,6 +1459,14 @@ void tst_QDateTime::operator_insert_extract()
         QCOMPARE(deserialised, expectedLocalTime);
         // Sanity check UTC times.
         QCOMPARE(deserialised.toUTC(), expectedLocalTime.toUTC());
+
+        if (dataStreamVersion != QDataStream::Qt_5_0) {
+            // Deserialised local datetime should be the same time of day,
+            // regardless of which timezone it was serialised in.
+            QDateTime localDeserialized;
+            dataStream >> localDeserialized;
+            QCOMPARE(localDeserialized, dateTime);
+        }
     }
 
     qputenv("TZ", previousTimeZone.toLocal8Bit().constData());