QObject: Handle pointers to incomplete types in auto-connections

The code for the QMetaMethod queuedConnectionTypes overload relied on
QMetaMethod::parameterMetaType and QMetaType::flags() to detect whether
we're dealing with a pointer (and then use the VoidStar metatype instead).
However, if the type was incomplete when the slot was defined, and the
type was not registered when connect was called, we would not find a
metatype for the argument.
However, in that case we might still be able to handle the method, by
checking whether the type name of the arguments ends with a "*".
This patch does that, fixing a regression from 5.15.

Pick-to: 6.5 6.4 6.2
Fixes: QTBUG-108537
Change-Id: I54cc48a3343444480ab9094fe1ebaaa5aa75cee0
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/corelib/kernel/qobject.cpp

@@ -84,6 +84,8 @@ static int *queuedConnectionTypes(const QMetaMethod &method)
             typeIds[i] = QMetaType::VoidStar;
         else
             typeIds[i] = metaType.id();
+        if (!typeIds[i] && method.parameterTypeName(i).endsWith('*'))
+            typeIds[i] = QMetaType::VoidStar;
         if (!typeIds[i]) {
             const QByteArray typeName = method.parameterTypeName(i);
             qCWarning(lcConnect,

tests/auto/corelib/kernel/qobject/tst_qobject.cpp

@@ -58,6 +58,7 @@ private slots:
     void connectNotify_connectSlotsByName();
     void connectDisconnectNotify_shadowing();
     void connectReferenceToIncompleteTypes();
+    void connectAutoQueuedIncomplete();
     void emitInDefinedOrder();
     void customTypes();
     void streamCustomTypes();
@@ -893,6 +894,42 @@ void tst_QObject::connectReferenceToIncompleteTypes() {
     QVERIFY(connection);
 }
 
+struct Incomplete2;
+class QObjectWithIncomplete2 : public QObject {
+    Q_OBJECT
+
+public:
+    QObjectWithIncomplete2(QObject *parent=nullptr) : QObject(parent) {}
+signals:
+    void signalWithIncomplete(Incomplete2 *ptr);
+public slots:
+    void slotWithIncomplete(Incomplete2 *) { calledSlot = true; }
+    void run() { Q_EMIT signalWithIncomplete(nullptr); }
+public:
+    bool calledSlot = false;
+};
+
+void tst_QObject::connectAutoQueuedIncomplete()
+{
+    auto objectWithIncomplete1 = new QObjectWithIncomplete2();
+    auto objectWithIncomplete2 = new QObjectWithIncomplete2();
+    auto t = new QThread(this);
+    auto cleanup = qScopeGuard([&](){
+        t->quit();
+        QVERIFY(t->wait());
+        delete objectWithIncomplete1;
+        delete objectWithIncomplete2;
+    });
+
+    t->start();
+    objectWithIncomplete2->moveToThread(t);
+
+    connect(objectWithIncomplete2, &QObjectWithIncomplete2::signalWithIncomplete,
+            objectWithIncomplete1, &QObjectWithIncomplete2::slotWithIncomplete);
+    QMetaObject::invokeMethod(objectWithIncomplete2, "run", Qt::QueuedConnection);
+    QTRY_VERIFY(objectWithIncomplete1->calledSlot);
+}
+
 static void connectDisconnectNotifyTestSlot() {}
 
 void tst_QObject::connectDisconnectNotifyPMF()