QML: Allow singletons to be created with a factory function

This is in line with what we do on qmlRegisterSingletonType(), and it
allows us to return singleton objects created independently of the
instantiation mechanism.

Change-Id: Ia6a077f5d22241593acd8cc87b3f65ae20f95667
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>

2 files changed, 37 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/testtypes.h b/tests/auto/qml/qqmllanguage/testtypes.h
index 518f52f4e7..cdcc5faed8 100644
--- a/tests/auto/qml/qqmllanguage/testtypes.h
+++ b/tests/auto/qml/qqmllanguage/testtypes.h
@@ -1563,6 +1563,26 @@ public:
     int own() const { return 93; }
 };
 
+class FactorySingleton : public QObject
+{
+    Q_OBJECT
+    QML_ELEMENT
+    QML_SINGLETON
+
+    Q_PROPERTY(int foo READ foo CONSTANT)
+public:
+
+    static FactorySingleton *create(QQmlEngine *, QJSEngine *)
+    {
+        return new FactorySingleton;
+    }
+
+    int foo() const { return 314; }
+
+private:
+    FactorySingleton() = default;
+};
+
 void registerTypes();
 
 #endif // TESTTYPES_H
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 74b7c0e64e..40a2ee887a 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -341,6 +341,7 @@ private slots:
     void checkURLtoURLObject();
     void registerValueTypes();
     void extendedNamespace();
+    void factorySingleton();
 
 private:
     QQmlEngine engine;
@@ -6048,6 +6049,22 @@ void tst_qqmllanguage::extendedNamespace()
     QCOMPARE(obj->property("fromExtension").toInt(), 9);
 }
 
+void tst_qqmllanguage::factorySingleton()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine);
+    c.setData("import StaticTest\n"
+              "import QtQml\n"
+              "QtObject {\n"
+              "    property int mine: FactorySingleton.foo\n"
+              "}", QUrl());
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+    QScopedPointer<QObject> obj(c.create());
+    QVERIFY(!obj.isNull());
+
+    QCOMPARE(obj->property("mine").toInt(), 314);
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"