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, 25 insertions, 0 deletions

diff --git a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
index a4e1f940fc..f42cc30fb1 100644
--- a/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
+++ b/tests/auto/gui/math3d/qquaternion/tst_qquaternion.cpp
@@ -116,6 +116,13 @@ void tst_QQuaternion::create()
     QCOMPARE(identity.scalar(), (qreal)1.0f);
     QVERIFY(identity.isIdentity());
 
+    QQuaternion negativeZeroIdentity(qreal(1.0), qreal(-0.0), qreal(-0.0), qreal(-0.0));
+    QCOMPARE(negativeZeroIdentity.x(), qreal(-0.0));
+    QCOMPARE(negativeZeroIdentity.y(), qreal(-0.0));
+    QCOMPARE(negativeZeroIdentity.z(), qreal(-0.0));
+    QCOMPARE(negativeZeroIdentity.scalar(), qreal(1.0));
+    QVERIFY(negativeZeroIdentity.isIdentity());
+
     QQuaternion v1(34.0f, 1.0f, 2.5f, -89.25f);
     QCOMPARE(v1.x(), (qreal)1.0f);
     QCOMPARE(v1.y(), (qreal)2.5f);
diff --git a/tests/auto/gui/math3d/qvectornd/tst_qvectornd.cpp b/tests/auto/gui/math3d/qvectornd/tst_qvectornd.cpp
index 72a4ecef97..4b6d9839a2 100644
--- a/tests/auto/gui/math3d/qvectornd/tst_qvectornd.cpp
+++ b/tests/auto/gui/math3d/qvectornd/tst_qvectornd.cpp
@@ -162,6 +162,11 @@ void tst_QVectorND::create2()
     QCOMPARE(null.y(), (qreal)0.0f);
     QVERIFY(null.isNull());
 
+    QVector2D nullNegativeZero(qreal(-0.0), qreal(-0.0));
+    QCOMPARE(nullNegativeZero.x(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.y(), (qreal)-0.0f);
+    QVERIFY(nullNegativeZero.isNull());
+
     QVector2D v1(1.0f, 2.5f);
     QCOMPARE(v1.x(), (qreal)1.0f);
     QCOMPARE(v1.y(), (qreal)2.5f);
@@ -252,6 +257,12 @@ void tst_QVectorND::create3()
     QCOMPARE(null.z(), (qreal)0.0f);
     QVERIFY(null.isNull());
 
+    QVector3D nullNegativeZero(qreal(-0.0), qreal(-0.0), qreal(-0.0));
+    QCOMPARE(nullNegativeZero.x(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.y(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.z(), (qreal)-0.0f);
+    QVERIFY(nullNegativeZero.isNull());
+
     QVector3D v1(1.0f, 2.5f, -89.25f);
     QCOMPARE(v1.x(), (qreal)1.0f);
     QCOMPARE(v1.y(), (qreal)2.5f);
@@ -379,6 +390,13 @@ void tst_QVectorND::create4()
     QCOMPARE(null.w(), (qreal)0.0f);
     QVERIFY(null.isNull());
 
+    QVector4D nullNegativeZero(qreal(-0.0), qreal(-0.0), qreal(-0.0), qreal(-0.0));
+    QCOMPARE(nullNegativeZero.x(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.y(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.z(), (qreal)-0.0f);
+    QCOMPARE(nullNegativeZero.w(), (qreal)-0.0f);
+    QVERIFY(nullNegativeZero.isNull());
+
     QVector4D v1(1.0f, 2.5f, -89.25f, 34.0f);
     QCOMPARE(v1.x(), (qreal)1.0f);
     QCOMPARE(v1.y(), (qreal)2.5f);