QML: Correctly detect extended types

Introduce a compile-time procedure to distinguish types without
extensions but with base type extensions from types with direct
extensions. Previously, we would have treated both cases the
same due to the C++ mechanism employed to mark a type as
extension-containing

As a drive by, make QQmlMetaType::clone() use class name of the
extension when we clone the extension

[ChangeLog][Important Behavior Changes] A derived type is no longer
considered to be extended itself when only its base type is extended.
Instead, the extension only exists on the base type.

Change-Id: I74092a5f88cad09c1e07626ae90bb986db0da73d
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

2 files changed, 39 insertions, 6 deletions

diff --git a/tests/auto/qml/qqmllanguage/testtypes.h b/tests/auto/qml/qqmllanguage/testtypes.h
index ca42ae02bc..54022b268f 100644
--- a/tests/auto/qml/qqmllanguage/testtypes.h
+++ b/tests/auto/qml/qqmllanguage/testtypes.h
@@ -1629,6 +1629,14 @@ public:
     int own() const { return 93; }
 };
 
+class ExtendedByNamespaceInParent : public ExtendedByNamespace
+{
+    Q_OBJECT
+    QML_ELEMENT
+public:
+    ExtendedByNamespaceInParent(QObject *parent = nullptr) : ExtendedByNamespace(parent) { }
+};
+
 class ExtendedNamespaceByObject : public QObject
 {
     Q_OBJECT
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index bfcd146b10..81d6e6f6a0 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -367,6 +367,7 @@ private slots:
     void multiExtension();
     void multiExtensionExtra();
     void multiExtensionIndirect();
+    void multiExtensionQmlTypes();
     void extensionSpecial();
     void invalidInlineComponent();
     void warnOnInjectedParameters();
@@ -6441,15 +6442,11 @@ void tst_qqmllanguage::multiExtensionExtra()
 
         QCOMPARE(QQmlPrivate::qmlExtendedObject(o.get(), 0), extension);
 
-        QObject *pseudoExtension = QQmlPrivate::qmlExtendedObject(o.get(), 1);
-        QVERIFY(pseudoExtension);
-        QVERIFY(qobject_cast<ExtensionB *>(pseudoExtension) != nullptr);
-
-        QObject *baseBaseTypeExtension = QQmlPrivate::qmlExtendedObject(o.get(), 2);
+        QObject *baseBaseTypeExtension = QQmlPrivate::qmlExtendedObject(o.get(), 1);
         QVERIFY(baseBaseTypeExtension);
         QVERIFY(qobject_cast<ExtensionB *>(baseBaseTypeExtension) != nullptr);
 
-        QObject *baseBaseBaseTypeExtension = QQmlPrivate::qmlExtendedObject(o.get(), 3);
+        QObject *baseBaseBaseTypeExtension = QQmlPrivate::qmlExtendedObject(o.get(), 2);
         QVERIFY(baseBaseBaseTypeExtension);
         QVERIFY(qobject_cast<ExtensionA *>(baseBaseBaseTypeExtension) != nullptr);
     }
@@ -6473,6 +6470,34 @@ void tst_qqmllanguage::multiExtensionIndirect()
     QCOMPARE(o->property("g").toInt(), 44); // NB: taken from the type, not from the extension!
 }
 
+void tst_qqmllanguage::multiExtensionQmlTypes()
+{
+    QQmlType extendedType = QQmlMetaType::qmlType(&MultiExtensionParent::staticMetaObject,
+                                                  QStringLiteral("StaticTest"), QTypeRevision());
+    QVERIFY(extendedType.isValid());
+    QVERIFY(extendedType.extensionFunction());
+    QVERIFY(extendedType.extensionMetaObject() != nullptr);
+
+    QQmlType nonExtendedType = QQmlMetaType::qmlType(&ExtendedInParent::staticMetaObject,
+                                                     QStringLiteral("StaticTest"), QTypeRevision());
+    QVERIFY(nonExtendedType.isValid());
+    QVERIFY(!nonExtendedType.extensionFunction());
+    QCOMPARE(nonExtendedType.extensionMetaObject(), nullptr);
+
+    QQmlType namespaceExtendedType = QQmlMetaType::qmlType(
+            &ExtendedByNamespace::staticMetaObject, QStringLiteral("StaticTest"), QTypeRevision());
+    QVERIFY(namespaceExtendedType.isValid());
+    QVERIFY(!namespaceExtendedType.extensionFunction()); // namespaces are non-creatable
+    QVERIFY(namespaceExtendedType.extensionMetaObject() != nullptr);
+
+    QQmlType namespaceNonExtendedType =
+            QQmlMetaType::qmlType(&ExtendedByNamespaceInParent::staticMetaObject,
+                                  QStringLiteral("StaticTest"), QTypeRevision());
+    QVERIFY(namespaceNonExtendedType.isValid());
+    QVERIFY(!namespaceNonExtendedType.extensionFunction());
+    QCOMPARE(namespaceNonExtendedType.extensionMetaObject(), nullptr);
+}
+
 void tst_qqmllanguage::extensionSpecial()
 {
     QQmlEngine engine;