Do not consider sign in qIsNull.

The current implementation of qIsNull only returns true if the value is
positive zero. This behaviour is not useful for use cases like
QPointF::isNull, where QPointF(-0, -0).isNull() will return false.
There doesn't seem to be a reason why the function exhibits this
behaviour (-0.0 is not accounted for in the unit tests), and for the
case of QSizeF::scale it causes a bug: qIsNull is used to check for
division by 0.0 before it proceeds, which fails in the case of -0.0.

Task-number: QTBUG-7303
Change-Id: I767e5280bd26614e8e78ae62b274eb9bc4ade385
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>

2 files changed, 36 insertions, 0 deletions

diff --git a/tests/auto/corelib/tools/qpointf/tst_qpointf.cpp b/tests/auto/corelib/tools/qpointf/tst_qpointf.cpp
index d949de5143..df8c7d1d54 100644
--- a/tests/auto/corelib/tools/qpointf/tst_qpointf.cpp
+++ b/tests/auto/corelib/tools/qpointf/tst_qpointf.cpp
@@ -111,6 +111,11 @@ void tst_QPointF::isNull()
     QVERIFY(!point.isNull());
     point.rx() -= 2;
     QVERIFY(!point.isNull());
+
+    QPointF nullNegativeZero(qreal(-0.0), qreal(-0.0));
+    QCOMPARE(nullNegativeZero.x(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.y(), (qreal)-0.0f);
+    QVERIFY(nullNegativeZero.isNull());
 }
 
 void tst_QPointF::manhattanLength_data()
diff --git a/tests/auto/corelib/tools/qsizef/tst_qsizef.cpp b/tests/auto/corelib/tools/qsizef/tst_qsizef.cpp
index a098abe5b0..67c8c4c550 100644
--- a/tests/auto/corelib/tools/qsizef/tst_qsizef.cpp
+++ b/tests/auto/corelib/tools/qsizef/tst_qsizef.cpp
@@ -48,6 +48,9 @@ class tst_QSizeF : public QObject
 {
     Q_OBJECT
 private slots:
+    void isNull_data();
+    void isNull();
+
     void scale();
 
     void expandedTo();
@@ -60,6 +63,34 @@ private slots:
     void transpose();
 };
 
+void tst_QSizeF::isNull_data()
+{
+    QTest::addColumn<qreal>("width");
+    QTest::addColumn<qreal>("height");
+    QTest::addColumn<bool>("isNull");
+
+    QTest::newRow("0, 0") << qreal(0.0) << qreal(0.0) << true;
+    QTest::newRow("-0, -0") << qreal(-0.0) << qreal(-0.0) << true;
+    QTest::newRow("0, -0") << qreal(0) << qreal(-0.0) << true;
+    QTest::newRow("-0, 0") << qreal(-0.0) << qreal(0) << true;
+    QTest::newRow("-0.1, 0") << qreal(-0.1) << qreal(0) << false;
+    QTest::newRow("0, -0.1") << qreal(0) << qreal(-0.1) << false;
+    QTest::newRow("0.1, 0") << qreal(0.1) << qreal(0) << false;
+    QTest::newRow("0, 0.1") << qreal(0) << qreal(0.1) << false;
+}
+
+void tst_QSizeF::isNull()
+{
+    QFETCH(qreal, width);
+    QFETCH(qreal, height);
+    QFETCH(bool, isNull);
+
+    QSizeF size(width, height);
+    QCOMPARE(size.width(), width);
+    QCOMPARE(size.height(), height);
+    QCOMPARE(size.isNull(), isNull);
+}
+
 void tst_QSizeF::scale() {
     QSizeF t1(10.4, 12.8);
     t1.scale(60.6, 60.6, Qt::IgnoreAspectRatio);