Skip superfluous property capture attempt

If a QQmlProperyBinding tries to capture a QProperty, there is nothing
to do as the dependency tracking happens in C++ anyway. Thus we can
avoid calling captureProperty.

Pick-to: 6.2
Change-Id: I96b2876d4b2ba10b00af8342be9beae660a95ef3
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

7 files changed, 11 insertions, 2 deletions

diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index 49a43860df..1d5d3dedf7 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -289,7 +289,8 @@ ReturnedValue QObjectWrapper::getProperty(ExecutionEngine *engine, QObject *obje
     QQmlEnginePrivate *ep = engine->qmlEngine() ? QQmlEnginePrivate::get(engine->qmlEngine()) : nullptr;
 
     if (ep && ep->propertyCapture && !property->isConstant())
-        ep->propertyCapture->captureProperty(object, property->coreIndex(), property->notifyIndex());
+        if (!property->isBindable() || ep->propertyCapture->expression->mustCaptureBindableProperty())
+            ep->propertyCapture->captureProperty(object, property->coreIndex(), property->notifyIndex());
 
     if (property->isVarProperty()) {
         QQmlVMEMetaObject *vmemo = QQmlVMEMetaObject::get(object);
diff --git a/src/qml/qml/qqmlbinding_p.h b/src/qml/qml/qqmlbinding_p.h
index 4e824fff03..6ba492f0e4 100644
--- a/src/qml/qml/qqmlbinding_p.h
+++ b/src/qml/qml/qqmlbinding_p.h
@@ -97,6 +97,8 @@ public:
 
     ~QQmlBinding() override;
 
+    bool mustCaptureBindableProperty() const final {return true;}
+
     void setTarget(const QQmlProperty &);
     bool setTarget(QObject *, const QQmlPropertyData &, const QQmlPropertyData *valueType);
     bool setTarget(QObject *, int coreIndex, bool coreIsAlias, int valueTypeIndex);
diff --git a/src/qml/qml/qqmlboundsignal_p.h b/src/qml/qml/qqmlboundsignal_p.h
index 0a3229b731..89635dec69 100644
--- a/src/qml/qml/qqmlboundsignal_p.h
+++ b/src/qml/qml/qqmlboundsignal_p.h
@@ -80,6 +80,8 @@ public:
     // evaluation of a bound signal expression doesn't return any value
     void evaluate(void **a);
 
+    bool mustCaptureBindableProperty() const final {return true;}
+
     QString expression() const;
     const QObject *target() const { return m_target; }
 
diff --git a/src/qml/qml/qqmlexpression_p.h b/src/qml/qml/qqmlexpression_p.h
index 3df839a6a2..26c0cddb9e 100644
--- a/src/qml/qml/qqmlexpression_p.h
+++ b/src/qml/qml/qqmlexpression_p.h
@@ -76,6 +76,7 @@ public:
     QVariant value(bool *isUndefined = nullptr);
 
     QV4::ReturnedValue v4value(bool *isUndefined = nullptr);
+    bool mustCaptureBindableProperty() const final {return true;}
 
     static inline QQmlExpressionPrivate *get(QQmlExpression *expr);
     static inline QQmlExpression *get(QQmlExpressionPrivate *expr);
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index c4c37a32be..f25fd0795c 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -394,7 +394,7 @@ void QQmlPropertyCapture::captureBindableProperty(
 {
     // if the property is a QPropery, and we're binding to a QProperty
     // the automatic capturing process already takes care of everything
-    if (typeid(QQmlPropertyBindingJS) == typeid(*expression))
+    if (!expression->mustCaptureBindableProperty())
         return;
     for (auto trigger = expression->qpropertyChangeTriggers; trigger;
          trigger = trigger->next) {
diff --git a/src/qml/qml/qqmljavascriptexpression_p.h b/src/qml/qml/qqmljavascriptexpression_p.h
index 7a741afb75..dc2289a357 100644
--- a/src/qml/qml/qqmljavascriptexpression_p.h
+++ b/src/qml/qml/qqmljavascriptexpression_p.h
@@ -158,6 +158,7 @@ public:
     void clearError();
     void clearActiveGuards();
     QQmlDelayedError *delayedError();
+    virtual bool mustCaptureBindableProperty() const {return true;}
 
     static QV4::ReturnedValue evalFunction(
             const QQmlRefPointer<QQmlContextData> &ctxt, QObject *scope, const QString &code,
diff --git a/src/qml/qml/qqmlpropertybinding_p.h b/src/qml/qml/qqmlpropertybinding_p.h
index d4b339b6e2..c2af93869a 100644
--- a/src/qml/qml/qqmlpropertybinding_p.h
+++ b/src/qml/qml/qqmlpropertybinding_p.h
@@ -70,6 +70,8 @@ class QQmlPropertyBinding;
 
 class Q_QML_PRIVATE_EXPORT QQmlPropertyBindingJS : public QQmlJavaScriptExpression
 {
+    bool mustCaptureBindableProperty() const final {return false;}
+
     friend class QQmlPropertyBinding;
     void expressionChanged() override;
     QQmlPropertyBinding *asBinding()