QV4QObjectWrapper: Store the whole signal

90be89d771425044a84e9e79e4e668e065acc825 changed the connection logic to
actually pass the receiver to connect in order to fix disconnect
cleanup. However, we omitted to change QObjectSlotDispatcher::impl
accordingly. The previous logic was:
- store the index of the signal in signalIndex
- In impl, in the call case, we would get passed the emitting object
  (sic!) as the receiver parameter. Then we would use the object and the
  signal index to obtain the QMetaMethod.
- From the QMetaMethod, we could get the signal's number of parameters.

After the aforementioned change, that does not work anymore: The
receiver is now the actual receiver of the signal, thus we get the wrong
method, and potentially the wrong number of parameters.
To fix this, we now store the complete QMetaMethod of the signal.

Change-Id: I868c51edf24a61d14eaf958ed7942da27f54a5c3
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit e7e4eba6875c0f375c4fd03af9b3ed9ea44d0ba1)
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

3 files changed, 21 insertions, 11 deletions

diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index 98d69b2f80..1d3b12f083 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -939,15 +939,15 @@ struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
 {
     QV4::PersistentValue function;
     QV4::PersistentValue thisObject;
-    int signalIndex;
+    QMetaMethod signal;
 
     QObjectSlotDispatcher()
         : QtPrivate::QSlotObjectBase(&impl)
-        , signalIndex(-1)
     {}
 
-    static void impl(int which, QSlotObjectBase *this_, QObject *r, void **metaArgs, bool *ret)
+    static void impl(int which, QSlotObjectBase *this_, QObject *receiver, void **metaArgs, bool *ret)
     {
+        Q_UNUSED(receiver);
         switch (which) {
         case Destroy: {
             delete static_cast<QObjectSlotDispatcher*>(this_);
@@ -963,7 +963,7 @@ struct QObjectSlotDispatcher : public QtPrivate::QSlotObjectBase
                 break;
 
             QQmlMetaObject::ArgTypeStorage storage;
-            int *argsTypes = QQmlMetaObject(r).methodParameterTypes(This->signalIndex, &storage, nullptr);
+            int *argsTypes = QQmlMetaObject::methodParameterTypes(This->signal, &storage, nullptr);
 
             int argCount = argsTypes ? argsTypes[0]:0;
 
@@ -1071,7 +1071,8 @@ ReturnedValue QObjectWrapper::method_connect(const FunctionObject *b, const Valu
     if (!signalObject)
         THROW_GENERIC_ERROR("Function.prototype.connect: cannot connect to deleted QObject");
 
-    if (signalObject->metaObject()->method(signalIndex).methodType() != QMetaMethod::Signal)
+    auto signalMetaMethod = signalObject->metaObject()->method(signalIndex);
+    if (signalMetaMethod.methodType() != QMetaMethod::Signal)
         THROW_GENERIC_ERROR("Function.prototype.connect: this object is not a signal");
 
     QV4::ScopedFunctionObject f(scope);
@@ -1091,7 +1092,7 @@ ReturnedValue QObjectWrapper::method_connect(const FunctionObject *b, const Valu
         THROW_GENERIC_ERROR("Function.prototype.connect: target this is not an object");
 
     QV4::QObjectSlotDispatcher *slot = new QV4::QObjectSlotDispatcher;
-    slot->signalIndex = signalIndex;
+    slot->signal = signalMetaMethod;
 
     slot->thisObject.set(scope.engine, object);
     slot->function.set(scope.engine, f);
diff --git a/src/qml/qml/qqmlmetaobject.cpp b/src/qml/qml/qqmlmetaobject.cpp
index 89c08f3841..b6454e083d 100644
--- a/src/qml/qml/qqmlmetaobject.cpp
+++ b/src/qml/qml/qqmlmetaobject.cpp
@@ -184,7 +184,7 @@ int *QQmlMetaObject::constructorParameterTypes(int index, ArgTypeStorage *dummy,
 }
 
 int *QQmlMetaObject::methodParameterTypes(const QMetaMethod &m, ArgTypeStorage *argStorage,
-                                          QByteArray *unknownTypeError) const
+                                          QByteArray *unknownTypeError)
 {
     Q_ASSERT(argStorage);
 
@@ -203,7 +203,17 @@ int *QQmlMetaObject::methodParameterTypes(const QMetaMethod &m, ArgTypeStorage *
         } else {
             if (argTypeNames.isEmpty())
                 argTypeNames = m.parameterTypes();
-            if (isNamedEnumerator(_m, argTypeNames.at(ii))) {
+            // hack only needed in Qt 6.1 to access the metaobject of the metamethod
+            // In 6.2 this method has been refactored and does not need acccess to the metaobject
+            union HackyAccessor {
+                HackyAccessor(QMetaMethod method) : m(method) {}
+                QMetaMethod m;
+                struct {
+                    const QMetaObject *mobj = nullptr;
+                } accessor;
+            };
+            HackyAccessor hack { m };
+            if (isNamedEnumerator(hack.accessor.mobj, argTypeNames.at(ii))) {
                 type = QMetaType::Int;
             } else if (type == QMetaType::UnknownType) {
                 if (unknownTypeError)
diff --git a/src/qml/qml/qqmlmetaobject_p.h b/src/qml/qml/qqmlmetaobject_p.h
index a5b9b758a8..299218c10a 100644
--- a/src/qml/qml/qqmlmetaobject_p.h
+++ b/src/qml/qml/qqmlmetaobject_p.h
@@ -101,11 +101,10 @@ public:
     // we need a helper to find the correct meta object and property/method index.
     static void resolveGadgetMethodOrPropertyIndex(QMetaObject::Call type, const QMetaObject **metaObject, int *index);
 
+    static int *methodParameterTypes(const QMetaMethod &method, ArgTypeStorage *argStorage,
+                              QByteArray *unknownTypeError);
 protected:
     const QMetaObject *_m = nullptr;
-    int *methodParameterTypes(const QMetaMethod &method, ArgTypeStorage *argStorage,
-                              QByteArray *unknownTypeError) const;
-
 };
 
 QQmlMetaObject::QQmlMetaObject(const QObject *o)