QQmlPropertyMap: Don't spuriously emit valueChanged() signal

The valueChanged() signal was emitted when the property was written with
the same value. This increased the potential for binding loops in user
code.

Change-Id: Ifeb8f6f23e2022aa35cb6cac7cf1a3dbc0e8ca2f
Task-number: QTBUG-48136
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 36 insertions, 1 deletions

diff --git a/src/qml/qml/qqmlopenmetaobject.cpp b/src/qml/qml/qqmlopenmetaobject.cpp
index 9188ba6174..0e60cae92f 100644
--- a/src/qml/qml/qqmlopenmetaobject.cpp
+++ b/src/qml/qml/qqmlopenmetaobject.cpp
@@ -272,7 +272,7 @@ int QQmlOpenMetaObject::metaCall(QObject *o, QMetaObject::Call c, int id, void *
             propertyRead(propId);
             *reinterpret_cast<QVariant *>(a[0]) = d->getData(propId);
         } else if (c == QMetaObject::WriteProperty) {
-            if (propId <= d->data.count() || d->data[propId].first != *reinterpret_cast<QVariant *>(a[0]))  {
+            if (propId >= d->data.count() || d->data[propId].first != *reinterpret_cast<QVariant *>(a[0]))  {
                 propertyWrite(propId);
                 QPair<QVariant, bool> &prop = d->getDataRef(propId);
                 prop.first = propertyWriteValue(propId, *reinterpret_cast<QVariant *>(a[0]));
diff --git a/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp b/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
index 2f3754e42d..1649cde4ce 100644
--- a/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
+++ b/tests/auto/qml/qqmlpropertymap/tst_qqmlpropertymap.cpp
@@ -65,6 +65,7 @@ private slots:
     void QTBUG_35233();
     void disallowExtending();
     void QTBUG_35906();
+    void QTBUG_48136();
 };
 
 class LazyPropertyMap : public QQmlPropertyMap, public QQmlParserStatus
@@ -467,6 +468,40 @@ void tst_QQmlPropertyMap::QTBUG_35906()
     QCOMPARE(value.toInt(), 42);
 }
 
+void tst_QQmlPropertyMap::QTBUG_48136()
+{
+    static const char key[] = "mykey";
+    QQmlPropertyMap map;
+
+    //
+    // Test that the notify signal is emitted correctly
+    //
+
+    const int propIndex = map.metaObject()->indexOfProperty(key);
+    const QMetaProperty prop = map.metaObject()->property(propIndex);
+    QSignalSpy notifySpy(&map, QByteArray::number(QSIGNAL_CODE) + prop.notifySignal().methodSignature());
+
+    map.insert(key, 42);
+    QCOMPARE(notifySpy.count(), 1);
+    map.insert(key, 43);
+    QCOMPARE(notifySpy.count(), 2);
+    map.insert(key, 43);
+    QCOMPARE(notifySpy.count(), 2);
+    map.insert(key, 44);
+    QCOMPARE(notifySpy.count(), 3);
+
+    //
+    // Test that the valueChanged signal is emitted correctly
+    //
+    QSignalSpy valueChangedSpy(&map, &QQmlPropertyMap::valueChanged);
+    map.setProperty(key, 44);
+    QCOMPARE(valueChangedSpy.count(), 0);
+    map.setProperty(key, 45);
+    QCOMPARE(valueChangedSpy.count(), 1);
+    map.setProperty(key, 45);
+    QCOMPARE(valueChangedSpy.count(), 1);
+}
+
 QTEST_MAIN(tst_QQmlPropertyMap)
 
 #include "tst_qqmlpropertymap.moc"