Ensure QmlAttached attribute does not leak into derived types in C++

Use the QmlTypeHasMarker helper struct to disable Qml type attributes
for types that are not marked with the corresponding macros but merely
inherit them from a superclass.

This fixes the use of the QML_ATTACHED macro, other commits will follow
for the other attributes.
[ChangeLog][QtQml][Important Behavior Changes]
Attached properties are only accessible from classes directly decorated
with the QML_ATTACHED macro. Derived classes cannot inherit attached
properties. Classes attached using the old way (via QQmlTypeInfo) are
unchanged.

Task-number: QTBUG-104177
Change-Id: Ia5393101ba17049bc0917e32668abc69a5ffe9d7
Reviewed-by: Maximilian Goldstein <max.goldstein@qt.io>

1 files changed, 53 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index d0d83ad9b1..96bef34a61 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -383,6 +383,7 @@ private slots:
     void componentMix();
     void uncreatableAttached();
     void resetGadgetProperty();
+    void leakingAttributesQmlAttached();
 
 private:
     QQmlEngine engine;
@@ -7210,6 +7211,58 @@ void tst_qqmllanguage::resetGadgetProperty()
     QCOMPARE(m->m_gadget.value(), 25);
 }
 
+void tst_qqmllanguage::leakingAttributesQmlAttached()
+{
+    // Check for leakage in the QML_ATTACHED macro
+    {
+        QQmlComponent c(&engine);
+        c.setData("import StaticTest\n"
+                  "import QtQuick\n"
+                  "Item {"
+                  "     OriginalQmlAttached.abc: true"
+                  "}",
+                  QUrl());
+        QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+        QScopedPointer<QObject> o(c.create());
+        QVERIFY(o);
+        QObject *attached = qmlAttachedPropertiesObject<OriginalQmlAttached>(o.data());
+        QVERIFY(attached);
+        QCOMPARE(attached->property("abc"), QVariant(true));
+    }
+    {
+        QQmlComponent c(&engine);
+        c.setData("import StaticTest\n"
+                  "import QtQuick\n"
+                  "Item {"
+                  "     LeakingQmlAttached.abc: true"
+                  "}",
+                  QUrl());
+        QVERIFY(!c.isReady());
+    }
+
+    {
+        QQmlComponent c(&engine);
+        c.setData("import StaticTest\n"
+                  "import QtQuick\n"
+                  "Item {"
+                  "     DerivedQmlAttached.anotherAbc: \"I am not a bool.\"\n"
+                  "     OriginalQmlAttached.abc: true"
+                  "}",
+                  QUrl());
+        QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+        QScopedPointer<QObject> o(c.create());
+        QVERIFY(o);
+
+        QObject *attached = qmlAttachedPropertiesObject<OriginalQmlAttached>(o.data());
+        QVERIFY(attached);
+        QCOMPARE(attached->property("abc"), QVariant(true));
+
+        attached = qmlAttachedPropertiesObject<DerivedQmlAttached>(o.data());
+        QVERIFY(attached);
+        QCOMPARE(attached->property("anotherAbc"), QVariant("I am not a bool."));
+    }
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"