Handle invalid dates properly for QDataStream versions < 5.

In Qt 5, when streaming an invalid QDate using a QDataStream version
earlier than Qt_5_0, QDate.jd is written and read as 0, which is an
invalid julian day for Qt versions earlier than 5.0. For Qt 5.0
however, 0 is a valid julian day, so when comparing a deserialised
invalid date (read using a QDataStream version < Qt_5_0) against a
default-constructed invalid date, they won't compare equal when they
should.

Task-number: QTBUG-26989

Change-Id: Ia76df493471f3b068c7d7187be20e3178eff2cc7
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 63 insertions, 1 deletions

diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index 62582d9212..905055c0fe 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -3624,7 +3624,8 @@ QDataStream &operator>>(QDataStream &in, QDate &date)
     if (in.version() < QDataStream::Qt_5_0) {
         quint32 jd;
         in >> jd;
-        date.jd = jd;
+        // Older versions consider 0 an invalid jd.
+        date.jd = (jd != 0 ? jd : QDate::nullJd());
     } else {
         qint64 jd;
         in >> jd;
diff --git a/tests/auto/corelib/tools/qdate/tst_qdate.cpp b/tests/auto/corelib/tools/qdate/tst_qdate.cpp
index e97025c6b6..2ce6ab2eb4 100644
--- a/tests/auto/corelib/tools/qdate/tst_qdate.cpp
+++ b/tests/auto/corelib/tools/qdate/tst_qdate.cpp
@@ -79,6 +79,8 @@ private slots:
     void operator_gt();
     void operator_lt_eq();
     void operator_gt_eq();
+    void operator_insert_extract_data();
+    void operator_insert_extract();
     void fromStringDateFormat_data();
     void fromStringDateFormat();
     void fromStringFormat_data();
@@ -840,6 +842,65 @@ void tst_QDate::operator_gt_eq()
     QVERIFY( d1 >= d2 );
 }
 
+Q_DECLARE_METATYPE(QDataStream::Version)
+
+void tst_QDate::operator_insert_extract_data()
+{
+    QTest::addColumn<QDate>("date");
+    QTest::addColumn<QDataStream::Version>("dataStreamVersion");
+
+    QMap<QDataStream::Version, QString> versionsToTest;
+    versionsToTest.insert(QDataStream::Qt_1_0, QString::fromLatin1("Qt_1_0"));
+    versionsToTest.insert(QDataStream::Qt_2_0, QString::fromLatin1("Qt_2_0"));
+    versionsToTest.insert(QDataStream::Qt_2_1, QString::fromLatin1("Qt_2_1"));
+    versionsToTest.insert(QDataStream::Qt_3_0, QString::fromLatin1("Qt_3_0"));
+    versionsToTest.insert(QDataStream::Qt_3_1, QString::fromLatin1("Qt_3_1"));
+    versionsToTest.insert(QDataStream::Qt_3_3, QString::fromLatin1("Qt_3_3"));
+    versionsToTest.insert(QDataStream::Qt_4_0, QString::fromLatin1("Qt_4_0"));
+    versionsToTest.insert(QDataStream::Qt_4_1, QString::fromLatin1("Qt_4_1"));
+    versionsToTest.insert(QDataStream::Qt_4_2, QString::fromLatin1("Qt_4_2"));
+    versionsToTest.insert(QDataStream::Qt_4_3, QString::fromLatin1("Qt_4_3"));
+    versionsToTest.insert(QDataStream::Qt_4_4, QString::fromLatin1("Qt_4_4"));
+    versionsToTest.insert(QDataStream::Qt_4_5, QString::fromLatin1("Qt_4_5"));
+    versionsToTest.insert(QDataStream::Qt_4_6, QString::fromLatin1("Qt_4_6"));
+    versionsToTest.insert(QDataStream::Qt_4_7, QString::fromLatin1("Qt_4_7"));
+    versionsToTest.insert(QDataStream::Qt_4_8, QString::fromLatin1("Qt_4_8"));
+    versionsToTest.insert(QDataStream::Qt_4_9, QString::fromLatin1("Qt_4_9"));
+    versionsToTest.insert(QDataStream::Qt_5_0, QString::fromLatin1("Qt_5_0"));
+
+    for (QMap<QDataStream::Version, QString>::ConstIterator it = versionsToTest.constBegin();
+            it != versionsToTest.constEnd(); ++it) {
+        const QString &version(it.value());
+        QTest::newRow(("(invalid) " + version).toLocal8Bit().constData()) << invalidDate() << it.key();
+        QTest::newRow(("(1, 1, 1) " + version).toLocal8Bit().constData()) << QDate(1, 1, 1) << it.key();
+        QTest::newRow(("(-1, 1, 1) " + version).toLocal8Bit().constData()) << QDate(-1, 1, 1) << it.key();
+        QTest::newRow(("(1995, 5, 20) " + version).toLocal8Bit().constData()) << QDate(1995, 5, 20) << it.key();
+
+        // Test minimums for quint32/qint64.
+        if (it.key() >= QDataStream::Qt_5_0)
+            QTest::newRow(("(-4714, 11, 24) " + version).toLocal8Bit().constData()) << QDate(-4714, 11, 24) << it.key();
+        else
+            QTest::newRow(("(-4713, 1, 2) " + version).toLocal8Bit().constData()) << QDate(-4713, 1, 2) << it.key();
+    }
+}
+
+void tst_QDate::operator_insert_extract()
+{
+    QFETCH(QDate, date);
+    QFETCH(QDataStream::Version, dataStreamVersion);
+
+    QByteArray byteArray;
+    QDataStream dataStream(&byteArray, QIODevice::ReadWrite);
+    dataStream.setVersion(dataStreamVersion);
+    dataStream << date;
+    dataStream.device()->reset();
+    QDate deserialised;
+    dataStream >> deserialised;
+    QCOMPARE(dataStream.status(), QDataStream::Ok);
+
+    QCOMPARE(deserialised, date);
+}
+
 void tst_QDate::fromStringDateFormat_data()
 {
     // Since we can't define an element of Qt::DateFormat, d1 will be the date