QtQml: Recognize JavaScript null as equivalent to nullptr QObject*

Otherwise we can go into infinite recursion there.

Pick-to: 6.2 6.4
Fixes: QTBUG-108651
Change-Id: I73a7c524b28d0eacb151f2090e3dce6afbc029d1
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 9d0c4d3519..6884826894 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -400,6 +400,7 @@ private slots:
     void signalInlineComponentArg();
     void functionSignatureEnforcement();
     void importPrecedence();
+    void nullIsNull();
 
 private:
     QQmlEngine engine;
@@ -7728,6 +7729,17 @@ void tst_qqmllanguage::importPrecedence()
     QCOMPARE(o2->property("theAgent").value<QObject *>(), nullptr);
 }
 
+void tst_qqmllanguage::nullIsNull()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("nullIsNull.qml"));
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+    QScopedPointer<QObject> o(c.create());
+    QVERIFY(!o.isNull());
+    QVERIFY(o->property("someProperty").value<QObject*>() != nullptr);
+    QTRY_COMPARE(o->property("someProperty").value<QObject*>(), nullptr);
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"