Allow overriding type registrations

Previously if the same revision of the same type was registered multiple
times, the first registration would dominate. Now, the last one does.

[ChangeLog] If you register the same revision of the same type multiple
times, the last registration is the one QML will use. This allows you to
override qmlRegisterSingleton*() calls, for example in order to register
a singleton instance for a type tagged with QML_SINGLETON.

Task-number: QTBUG-79331
Change-Id: I32a2acabc89af6faa89d8ccb6380a473bc8b8ddd
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 38 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/testtypes.cpp b/tests/auto/qml/qqmllanguage/testtypes.cpp
index 462745eb93..0ddb1b1491 100644
--- a/tests/auto/qml/qqmllanguage/testtypes.cpp
+++ b/tests/auto/qml/qqmllanguage/testtypes.cpp
@@ -120,6 +120,7 @@ void registerTypes()
     qmlRegisterType<DeferredProperties>("Test", 1, 0, "DeferredProperties");
 
     qmlRegisterTypesAndRevisions<Extended, Foreign, ForeignExtended>("Test", 1);
+    qmlRegisterTypesAndRevisions<BareSingleton>("Test", 1);
 }
 
 QVariant myCustomVariantTypeConverter(const QString &data)
diff --git a/tests/auto/qml/qqmllanguage/testtypes.h b/tests/auto/qml/qqmllanguage/testtypes.h
index bfbd3e66f5..a7410e190b 100644
--- a/tests/auto/qml/qqmllanguage/testtypes.h
+++ b/tests/auto/qml/qqmllanguage/testtypes.h
@@ -1455,6 +1455,19 @@ class ForeignExtended
     QML_EXTENDED(Extension)
 };
 
+class BareSingleton : public QObject
+{
+    Q_OBJECT
+    QML_SINGLETON
+    QML_ELEMENT
+
+public:
+    BareSingleton(QObject *parent = nullptr) : QObject(parent)
+    {
+        setObjectName("statically registered");
+    }
+};
+
 void registerTypes();
 
 #endif // TESTTYPES_H
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index fca398d7b2..7b4662a5cd 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -310,6 +310,7 @@ private slots:
     void selfReferencingSingleton();
 
     void listContainingDeletedObject();
+    void overrideSingleton();
 
 private:
     QQmlEngine engine;
@@ -5375,6 +5376,29 @@ void tst_qqmllanguage::listContainingDeletedObject()
 
 }
 
+void tst_qqmllanguage::overrideSingleton()
+{
+    auto check = [](const QString &name) {
+        const QByteArray testQml = "import Test 1.0\n"
+                                   "import QtQml 2.0\n"
+                                   "QtObject { objectName: BareSingleton.objectName }";
+        QQmlEngine engine;
+        QQmlComponent component(&engine, nullptr);
+        component.setData(testQml, QUrl());
+        QVERIFY(component.isReady());
+        QScopedPointer<QObject> obj(component.create());
+        QCOMPARE(obj->objectName(), name);
+    };
+
+    check("statically registered");
+
+    BareSingleton singleton;
+    singleton.setObjectName("dynamically registered");
+    qmlRegisterSingletonInstance("Test", 1, 0, "BareSingleton", &singleton);
+
+    check("dynamically registered");
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"