QVectorND: fix qFuzzyCompare() precondition violation

qFuzzyCompare() requires that neither argument is numerically
zero. This cannot be guaranteed for the vector elements.

Fix by using the new QtPrivate::fuzzyCompare() function, which does
things in the correct way.

As a drive-by, put the operators at the beginning of continued lines,
as requested by https://wiki.qt.io/Qt_Coding_Style#Line_breaks Item 2.

Amends the start of the public history.

Pick-to: 6.10 6.8 6.5
Task-number: QTBUG-142020
Change-Id: I55cfb520bda53e12532923005bb1ee6396b124f2
Reviewed-by: Ivan Solovev <[email protected]>

Author: marcmutz

src/gui/math3d/qvectornd.cpp

@@ -375,7 +375,8 @@ QT_BEGIN_NAMESPACE
 */
 bool qFuzzyCompare(QVector2D v1, QVector2D v2) noexcept
 {
-    return qFuzzyCompare(v1.v[0], v2.v[0]) && qFuzzyCompare(v1.v[1], v2.v[1]);
+    return QtPrivate::fuzzyCompare(v1.v[0], v2.v[0])
+        && QtPrivate::fuzzyCompare(v1.v[1], v2.v[1]);
 }
 
 #ifndef QT_NO_VECTOR3D
@@ -979,9 +980,9 @@ QVector3D QVector3D::unproject(const QMatrix4x4 &modelView, const QMatrix4x4 &pr
 */
 bool qFuzzyCompare(QVector3D v1, QVector3D v2) noexcept
 {
-    return qFuzzyCompare(v1.v[0], v2.v[0]) &&
-            qFuzzyCompare(v1.v[1], v2.v[1]) &&
-            qFuzzyCompare(v1.v[2], v2.v[2]);
+    return QtPrivate::fuzzyCompare(v1.v[0], v2.v[0])
+        && QtPrivate::fuzzyCompare(v1.v[1], v2.v[1])
+        && QtPrivate::fuzzyCompare(v1.v[2], v2.v[2]);
 }
 
 #ifndef QT_NO_VECTOR2D
@@ -1501,10 +1502,10 @@ QDataStream &operator>>(QDataStream &stream, QVector3D &vector)
 */
 bool qFuzzyCompare(QVector4D v1, QVector4D v2) noexcept
 {
-    return qFuzzyCompare(v1.v[0], v2.v[0]) &&
-            qFuzzyCompare(v1.v[1], v2.v[1]) &&
-            qFuzzyCompare(v1.v[2], v2.v[2]) &&
-            qFuzzyCompare(v1.v[3], v2.v[3]);
+    return QtPrivate::fuzzyCompare(v1.v[0], v2.v[0])
+        && QtPrivate::fuzzyCompare(v1.v[1], v2.v[1])
+        && QtPrivate::fuzzyCompare(v1.v[2], v2.v[2])
+        && QtPrivate::fuzzyCompare(v1.v[3], v2.v[3]);
 }
 
 #ifndef QT_NO_VECTOR2D