QQmlBinding::dependencies: Handle QProperty

The method did not consider QProperty properties, as those do not show
up via the active guards mechanism.
At some point, we probably also want to introduce
QQmlAnyBinding::dependencies, as there are now bindings which do not
derive from QQmlBinding.

Change-Id: Ib4b227a440e9494c09d92028f9eaa5ad1e87342f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
(cherry picked from commit de28bc00f514c3ee8d8fd3166973c063766e77fd)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

5 files changed, 52 insertions, 1 deletions

diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index 62275c792e..c137a85654 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -772,11 +772,17 @@ QVector<QQmlProperty> QQmlBinding::dependencies() const
         for (int i = 0; i < senderMeta->propertyCount(); i++) {
             QMetaProperty property = senderMeta->property(i);
             if (property.notifySignalIndex() == QMetaObjectPrivate::signal(senderMeta, guard->signalIndex()).methodIndex()) {
-                dependencies.push_back(QQmlProperty(senderObject, QString::fromUtf8(senderObject->metaObject()->property(i).name())));
+                dependencies.push_back(QQmlProperty(senderObject, QString::fromUtf8(property.name())));
             }
         }
     }
 
+    for (auto trigger = qpropertyChangeTriggers; trigger; trigger = trigger->next) {
+        QMetaProperty prop = trigger->property();
+        if (prop.isValid())
+            dependencies.push_back(QQmlProperty(trigger->target, QString::fromUtf8(prop.name())));
+    }
+
     return dependencies;
 }
 
diff --git a/src/qml/qml/qqmlbinding_p.h b/src/qml/qml/qqmlbinding_p.h
index 6ba492f0e4..7c3dab98c2 100644
--- a/src/qml/qml/qqmlbinding_p.h
+++ b/src/qml/qml/qqmlbinding_p.h
@@ -133,6 +133,7 @@ public:
      * Call this method from the UI thread.
      */
     QVector<QQmlProperty> dependencies() const;
+    // This method is used internally to check whether a binding is constant and can be removed
     virtual bool hasDependencies() const;
 
 protected:
diff --git a/src/qml/qml/qqmlengine_p.h b/src/qml/qml/qqmlengine_p.h
index 499f9dd492..18a0164028 100644
--- a/src/qml/qml/qqmlengine_p.h
+++ b/src/qml/qml/qqmlengine_p.h
@@ -75,6 +75,7 @@
 #include <QtCore/qmutex.h>
 #include <QtCore/qstring.h>
 #include <QtCore/qthread.h>
+#include <QtCore/QMetaProperty>
 
 #include <private/qobject_p.h>
 
@@ -132,6 +133,8 @@ struct QPropertyChangeTrigger : QPropertyObserver {
     QObject *target = nullptr;
     int propertyIndex = 0;
     static void trigger(QPropertyObserver *, QUntypedPropertyData *);
+
+    QMetaProperty property() const;
 };
 
 struct TriggerList : QPropertyChangeTrigger {
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index d2f24166a9..1e32cd6926 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -541,6 +541,16 @@ void QPropertyChangeTrigger::trigger(QPropertyObserver *observer, QUntypedProper
     This->m_expression->expressionChanged();
 }
 
+QMetaProperty QPropertyChangeTrigger::property() const
+{
+    if (!target)
+        return {};
+    auto const mo = target->metaObject();
+    if (!mo)
+        return {};
+    return mo->property(propertyIndex);
+}
+
 QPropertyChangeTrigger *QQmlJavaScriptExpression::allocatePropertyChangeTrigger(QObject *target, int propertyIndex)
 {
     auto trigger = QQmlEnginePrivate::get(engine())->qPropertyTriggerPool.New( this );
diff --git a/tests/auto/qml/bindingdependencyapi/tst_bindingdependencyapi.cpp b/tests/auto/qml/bindingdependencyapi/tst_bindingdependencyapi.cpp
index dfb595ffb0..81162c2c8a 100644
--- a/tests/auto/qml/bindingdependencyapi/tst_bindingdependencyapi.cpp
+++ b/tests/auto/qml/bindingdependencyapi/tst_bindingdependencyapi.cpp
@@ -48,6 +48,7 @@ private slots:
     void testConditionalDependencies_data();
     void testConditionalDependencies();
     void testBindingLoop();
+    void testQproperty();
 
 private:
     bool findProperties(const QVector<QQmlProperty> &properties, QObject *obj, const QString &propertyName, const QVariant &value);
@@ -354,6 +355,36 @@ void tst_bindingdependencyapi::testBindingLoop()
     delete rect;
 }
 
+void tst_bindingdependencyapi::testQproperty()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine);
+    c.setData(QByteArray("import QtQuick 2.0\n"
+                      "Item {\n"
+                          "id: root\n"
+                          "Text {\n"
+                              "id: label\n"
+                              "text: root.x\n"
+                          "}\n"
+                      "}"), QUrl());
+    QScopedPointer<QObject> root(c.create());
+    QVERIFY(!root.isNull());
+    QObject *text = root->findChildren<QQuickText *>().front();
+    QVERIFY(text);
+    auto data = QQmlData::get(text);
+    QVERIFY(data);
+    auto b = data->bindings;
+    QVERIFY(b);
+    auto binding = dynamic_cast<QQmlBinding*>(b);
+    QVERIFY(binding);
+    auto dependencies = binding->dependencies();
+    QCOMPARE(dependencies.size(), 1);
+    auto dependency = dependencies.front();
+    QVERIFY(dependency.isValid());
+    QCOMPARE(quintptr(dependency.object()), quintptr(root.get()));
+    QCOMPARE(dependency.property().name(), "x");
+}
+
 QTEST_MAIN(tst_bindingdependencyapi)
 
 #include "tst_bindingdependencyapi.moc"