QDateTime - Fix toTimeSpec() for invalid datetimes

Check if the datetime is valid before converting it to a different time
spec.  If it is invalid then just change the spec to keep behavior
consistent with 5.1.

Task-number: QTBUG-34020
Change-Id: I6630ec1d50f810a2178ab3222bd32af018085f81
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 51 insertions, 3 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 9ddb96b424..dec4d9aaa4 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -3921,7 +3921,16 @@ qint64 QDateTime::msecsTo(const QDateTime &other) const
 
 QDateTime QDateTime::toTimeSpec(Qt::TimeSpec spec) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), spec, 0);
+    if (d->m_spec == spec && (spec == Qt::UTC || spec == Qt::LocalTime))
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setTimeSpec(spec);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), spec, 0);
 }
 
 /*!
@@ -3939,7 +3948,16 @@ QDateTime QDateTime::toTimeSpec(Qt::TimeSpec spec) const
 
 QDateTime QDateTime::toOffsetFromUtc(int offsetSeconds) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), Qt::OffsetFromUTC, offsetSeconds);
+    if (d->m_spec == Qt::OffsetFromUTC && d->m_offsetFromUtc == offsetSeconds)
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setOffsetFromUtc(offsetSeconds);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), Qt::OffsetFromUTC, offsetSeconds);
 }
 
 #ifndef QT_BOOTSTRAPPED
@@ -3953,7 +3971,16 @@ QDateTime QDateTime::toOffsetFromUtc(int offsetSeconds) const
 
 QDateTime QDateTime::toTimeZone(const QTimeZone &timeZone) const
 {
-    return fromMSecsSinceEpoch(toMSecsSinceEpoch(), timeZone);
+    if (d->m_spec == Qt::TimeZone && d->m_timeZone == timeZone)
+        return *this;
+
+    if (!isValid()) {
+        QDateTime ret = *this;
+        ret.setTimeZone(timeZone);
+        return ret;
+    }
+
+    return fromMSecsSinceEpoch(d->toMSecsSinceEpoch(), timeZone);
 }
 #endif // QT_BOOTSTRAPPED
 
diff --git a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
index b8b970121c..0c560df423 100644
--- a/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
+++ b/tests/auto/corelib/tools/qdatetime/tst_qdatetime.cpp
@@ -147,6 +147,8 @@ private slots:
     void daylightTransitions() const;
     void timeZones() const;
 
+    void invalid() const;
+
 private:
     bool europeanTimeZone;
     QDate defDate() const { return QDate(1900, 1, 1); }
@@ -2899,5 +2901,24 @@ void tst_QDateTime::timeZones() const
     QCOMPARE(hourAfterStd.toMSecsSinceEpoch(), dstToStdMSecs + 3600000);
 }
 
+void tst_QDateTime::invalid() const
+{
+    QDateTime invalidDate = QDateTime(QDate(0, 0, 0), QTime(-1, -1, -1));
+    QCOMPARE(invalidDate.isValid(), false);
+    QCOMPARE(invalidDate.timeSpec(), Qt::LocalTime);
+
+    QDateTime utcDate = invalidDate.toUTC();
+    QCOMPARE(utcDate.isValid(), false);
+    QCOMPARE(utcDate.timeSpec(), Qt::UTC);
+
+    QDateTime offsetDate = invalidDate.toOffsetFromUtc(3600);
+    QCOMPARE(offsetDate.isValid(), false);
+    QCOMPARE(offsetDate.timeSpec(), Qt::OffsetFromUTC);
+
+    QDateTime tzDate = invalidDate.toTimeZone(QTimeZone("Europe/Oslo"));
+    QCOMPARE(tzDate.isValid(), false);
+    QCOMPARE(tzDate.timeSpec(), Qt::TimeZone);
+}
+
 QTEST_APPLESS_MAIN(tst_QDateTime)
 #include "tst_qdatetime.moc"