V4: Write back value type references after function calls

If we call a function on a value type reference we have to assume that
the value has changed. Therefore, we need to write back, just like we do
when writing a property on the reference.

Fixes: QTBUG-91783
Pick-to: 6.1 5.15
Change-Id: I6d2e957997d64e40e42eb5210350b6592a92ee26
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 42 insertions, 47 deletions

diff --git a/src/qml/qml/qqmlvaluetypewrapper.cpp b/src/qml/qml/qqmlvaluetypewrapper.cpp
index b3c073a3f0..5d34a593a5 100644
--- a/src/qml/qml/qqmlvaluetypewrapper.cpp
+++ b/src/qml/qml/qqmlvaluetypewrapper.cpp
@@ -64,36 +64,6 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_LOGGING_CATEGORY(lcBindingRemoval)
 
 DEFINE_OBJECT_VTABLE(QV4::QQmlValueTypeWrapper);
-
-namespace QV4 {
-namespace Heap {
-
-struct QQmlValueTypeReference : QQmlValueTypeWrapper
-{
-    void init() {
-        QQmlValueTypeWrapper::init();
-        object.init();
-    }
-    void destroy() {
-        object.destroy();
-        QQmlValueTypeWrapper::destroy();
-    }
-    QV4QPointer<QObject> object;
-    int property;
-};
-
-}
-
-struct QQmlValueTypeReference : public QQmlValueTypeWrapper
-{
-    V4_OBJECT2(QQmlValueTypeReference, QQmlValueTypeWrapper)
-    V4_NEEDS_DESTROY
-
-    bool readReferenceValue() const;
-};
-
-}
-
 DEFINE_OBJECT_VTABLE(QV4::QQmlValueTypeReference);
 
 using namespace QV4;
@@ -693,23 +663,8 @@ bool QQmlValueTypeWrapper::virtualPut(Managed *m, PropertyKey id, const Value &v
     void *gadget = r->d()->gadgetPtr();
     property.writeOnGadget(gadget, v);
 
-
-    if (reference) {
-        if (writeBackPropertyType == QMetaType::fromType<QVariant>()) {
-            QVariant variantReferenceValue = r->d()->toVariant();
-
-            int flags = 0;
-            int status = -1;
-            void *a[] = { &variantReferenceValue, nullptr, &status, &flags };
-            QMetaObject::metacall(reference->d()->object, QMetaObject::WriteProperty, reference->d()->property, a);
-
-        } else {
-            int flags = 0;
-            int status = -1;
-            void *a[] = { r->d()->gadgetPtr(), nullptr, &status, &flags };
-            QMetaObject::metacall(reference->d()->object, QMetaObject::WriteProperty, reference->d()->property, a);
-        }
-    }
+    if (reference)
+        reference->d()->writeBack();
 
     return true;
 }
diff --git a/src/qml/qml/qqmlvaluetypewrapper_p.h b/src/qml/qml/qqmlvaluetypewrapper_p.h
index 0eb1088a64..ed58157c26 100644
--- a/src/qml/qml/qqmlvaluetypewrapper_p.h
+++ b/src/qml/qml/qqmlvaluetypewrapper_p.h
@@ -111,6 +111,38 @@ private:
     const QMetaObject *m_metaObject;
 };
 
+struct QQmlValueTypeReference : QQmlValueTypeWrapper
+{
+    void init() {
+        QQmlValueTypeWrapper::init();
+        object.init();
+    }
+    void destroy() {
+        object.destroy();
+        QQmlValueTypeWrapper::destroy();
+    }
+
+    void writeBack() {
+        const QMetaProperty writebackProperty = object->metaObject()->property(property);
+        if (!writebackProperty.isWritable())
+            return;
+
+        int flags = 0;
+        int status = -1;
+        if (writebackProperty.metaType() == QMetaType::fromType<QVariant>()) {
+            QVariant variantReferenceValue = toVariant();
+            void *a[] = { &variantReferenceValue, nullptr, &status, &flags };
+            QMetaObject::metacall(object, QMetaObject::WriteProperty, property, a);
+        } else {
+            void *a[] = { gadgetPtr(), nullptr, &status, &flags };
+            QMetaObject::metacall(object, QMetaObject::WriteProperty, property, a);
+        }
+    }
+
+    QV4QPointer<QObject> object;
+    int property;
+};
+
 }
 
 struct Q_QML_EXPORT QQmlValueTypeWrapper : Object
@@ -149,6 +181,14 @@ public:
     static void initProto(ExecutionEngine *v4);
 };
 
+struct QQmlValueTypeReference : public QQmlValueTypeWrapper
+{
+    V4_OBJECT2(QQmlValueTypeReference, QQmlValueTypeWrapper)
+    V4_NEEDS_DESTROY
+
+    bool readReferenceValue() const;
+};
+
 }
 
 QT_END_NAMESPACE