tst_qqmlproperty: Fix interfaceBinding crash on MSVC 2019

Change-Id: I4bb4a66b7ccca838e058962bbc297659b273c78e
Done-with: Fabian Kosmale <fabian.kosmale@qt.io>
Fixes: QTBUG-84416
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 31 insertions, 10 deletions

diff --git a/src/qml/qml/qqmlproperty.cpp b/src/qml/qml/qqmlproperty.cpp
index 8ffdf1738c..68127f8686 100644
--- a/src/qml/qml/qqmlproperty.cpp
+++ b/src/qml/qml/qqmlproperty.cpp
@@ -1417,10 +1417,14 @@ bool QQmlPropertyPrivate::write(
 
         if (!ok && QQmlMetaType::isInterface(propertyType)) {
             auto valueAsQObject = qvariant_cast<QObject *>(value);
-            if (valueAsQObject && valueAsQObject->qt_metacast(QQmlMetaType::interfaceIId(propertyType))) {
+
+            if (void *interface = valueAsQObject
+                        ? valueAsQObject->qt_metacast(QQmlMetaType::interfaceIId(propertyType))
+                        : nullptr;
+                interface) {
                 // this case can occur when object has an interface type
                 // and the variant contains a type implementing the interface
-                return property.writeProperty(object, const_cast<void *>(value.constData()), flags);
+                return property.writeProperty(object, &interface, flags);
             }
         }
 
diff --git a/tests/auto/qml/qqmlproperty/interfaces.h b/tests/auto/qml/qqmlproperty/interfaces.h
index 2c06c5f594..f89b47efbe 100644
--- a/tests/auto/qml/qqmlproperty/interfaces.h
+++ b/tests/auto/qml/qqmlproperty/interfaces.h
@@ -30,8 +30,11 @@
 #define INTERFACES_H
 
 #include <QtQml/qqml.h>
+#include <QTest>
 
 struct Interface {
+    // non-virtual, non-QObject interfaces are not supported
+    virtual ~Interface() {};
 };
 
 QT_BEGIN_NAMESPACE
@@ -39,7 +42,7 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_INTERFACE(Interface, MyInterface_iid);
 QT_END_NAMESPACE
 
-class A : public QObject, Interface {
+class A : public QObject, public Interface {
     Q_OBJECT
     Q_INTERFACES(Interface)
 };
@@ -57,6 +60,9 @@ struct Interface2
 {
     Q_GADGET
     QML_INTERFACE
+public:
+    // non-virtual, non-QObject interfaces are not supported
+    virtual ~Interface2() {};
 };
 
 QT_BEGIN_NAMESPACE
@@ -64,7 +70,8 @@ QT_BEGIN_NAMESPACE
 Q_DECLARE_INTERFACE(Interface2, MyInterface2_iid);
 QT_END_NAMESPACE
 
-class A2 : public QObject, Interface2 {
+class A2 : public QObject, public Interface2
+{
     Q_OBJECT
     QML_ELEMENT
     Q_INTERFACES(Interface2)
@@ -94,7 +101,8 @@ public:
     }
     void setInterface(Interface* interface)
     {
-        QObject* object = reinterpret_cast<QObject*>(interface);
+        QObject* object = dynamic_cast<A*>(interface); // we know that we only get an A
+        QVERIFY(object);
         m_testValue = object->property("i").toInt();
         emit testValueChanged();
         if (m_interface == interface)
@@ -135,7 +143,7 @@ public:
     }
     void setInterface(Interface2* interface2)
     {
-        QObject* object = reinterpret_cast<QObject*>(interface2);
+        QObject* object = dynamic_cast<QObject*>(interface2);
         m_testValue = object->property("i").toInt();
         emit testValueChanged();
         if (m_interface == interface2)
diff --git a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
index 1fd0b1a7d1..10a4881579 100644
--- a/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
+++ b/tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp
@@ -2146,15 +2146,23 @@ void tst_qqmlproperty::nullPropertyBinding()
 
 void tst_qqmlproperty::interfaceBinding()
 {
-#if defined(Q_CC_MSVC)
-    QSKIP("Test disabled due to crashing. See QTBUG-84416");
-#endif
     qmlRegisterInterface<Interface>("Interface", 1);
     qmlRegisterType<A>("io.qt.bugreports", 1, 0, "A");
     qmlRegisterType<B>("io.qt.bugreports", 1, 0, "B");
     qmlRegisterType<C>("io.qt.bugreports", 1, 0, "C");
     qmlRegisterType<InterfaceConsumer>("io.qt.bugreports", 1, 0, "InterfaceConsumer");
 
+    // Currently registration macros such as QML_ELEMENT are broken when there's multiple inheritance (QTBUG-88623)
+    // So these types have to be registered again.
+    // TODO: Fix QTBUG-88623 and remove this hack
+    qmlRegisterInterface<Interface2>("Interface2", 2);
+    qmlRegisterType<A2>("io.qt.bugreports", 2, 0, "A2");
+    qmlRegisterType<A2>("io.qt.bugreports", 2, 0, "A2");
+    qmlRegisterType<B2>("io.qt.bugreports", 2, 0, "B2");
+    qmlRegisterType<C2>("io.qt.bugreports", 2, 0, "C2");
+    qmlRegisterType<InterfaceConsumer2>("io.qt.bugreports", 2, 0, "InterfaceConsumer2");
+
+
     const QVector<QUrl> urls = {
         testFileUrl("interfaceBinding.qml"),
         testFileUrl("interfaceBinding2.qml")
@@ -2164,7 +2172,8 @@ void tst_qqmlproperty::interfaceBinding()
         QQmlEngine engine;
         QQmlComponent component(&engine, url);
         QScopedPointer<QObject> root(component.create());
-        QVERIFY(root);
+        QVERIFY2(root, qPrintable(component.errorString()));
+
         QCOMPARE(root->findChild<QObject*>("a1")->property("testValue").toInt(), 42);
         QCOMPARE(root->findChild<QObject*>("a2")->property("testValue").toInt(), 43);
         QCOMPARE(root->findChild<QObject*>("a3")->property("testValue").toInt(), 44);