qqmltypecompiler: Be more careful when resolving enums

Task-number: QTBUG-83703
Pick-to: 5.15
Change-Id: I60c0811e47e0cd3b63b3ddfebb9bb6e9ab7f4f40
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 77 insertions, 4 deletions

diff --git a/src/qml/qml/qqmltypecompiler.cpp b/src/qml/qml/qqmltypecompiler.cpp
index a9f5cdbf8d..a49722f57e 100644
--- a/src/qml/qml/qqmltypecompiler.cpp
+++ b/src/qml/qml/qqmltypecompiler.cpp
@@ -616,10 +616,20 @@ bool QQmlEnumTypeResolver::tryQualifiedEnumAssignment(const QmlIR::Object *obj,
     bool ok = false;
 
     auto *tr = resolvedType(obj->inheritedTypeNameIndex);
-    if (type.isValid() && tr && tr->type() == type) {
-        // When these two match, we can short cut the search
-        QMetaProperty mprop = propertyCache->firstCppMetaObject()->property(prop->coreIndex());
-        QMetaEnum menum = mprop.enumerator();
+
+    // When these two match, we can short cut the search, unless...
+    bool useFastPath = type.isValid() && tr && tr->type() == type;
+    QMetaProperty mprop;
+    QMetaEnum menum;
+    if (useFastPath) {
+        mprop = propertyCache->firstCppMetaObject()->property(prop->coreIndex());
+        menum = mprop.enumerator();
+        // ...the enumerator merely comes from a related metaobject, but the enum scope does not match
+        // the typename we resolved
+        if (!menum.isScoped() && scopedEnumName.isEmpty() && typeName != QString::fromUtf8(menum.scope()))
+            useFastPath = false;;
+    }
+    if (useFastPath) {
         QByteArray enumName = enumValue.toUtf8();
         if (menum.isScoped() && !scopedEnumName.isEmpty() && enumName != scopedEnumName.toUtf8())
             return true;
diff --git a/tests/auto/qml/qqmllanguage/data/enumScopeLeak.qml b/tests/auto/qml/qqmllanguage/data/enumScopeLeak.qml
new file mode 100644
index 0000000000..b4bdc54f86
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/enumScopeLeak.qml
@@ -0,0 +1,6 @@
+import QtQml 2.0
+import test 1.0
+
+ObjectC {
+    testEnum: ObjectC.TestValue1
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index 77e545722a..411ff7df56 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -228,6 +228,7 @@ private slots:
     void scopedEnum();
     void scopedEnumsWithNameClash();
     void scopedEnumsWithResolvedNameClash();
+    void enumNoScopeLeak();
     void qmlEnums();
     void literals_data();
     void literals();
@@ -4155,6 +4156,62 @@ void tst_qqmllanguage::scopedEnumsWithResolvedNameClash()
     QVERIFY(obj->property("success").toBool());
 }
 
+class ObjectA : public QObject
+{
+    Q_OBJECT
+
+public:
+
+    enum TestEnum {
+        Default = 42,
+        TestValue1,
+        TestValue2
+    };
+    Q_ENUM(TestEnum)
+
+    ObjectA() = default;
+};
+
+class ObjectB : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(ObjectA::TestEnum testEnum READ testEnum WRITE setTestEnum NOTIFY testEnumChanged)
+
+public:
+    ObjectB() = default;
+    ObjectA::TestEnum testEnum() const {return m_testEnum;}
+
+public slots:
+    void setTestEnum(ObjectA::TestEnum testEnum) {auto old = m_testEnum; m_testEnum = testEnum; if (old != m_testEnum) testEnumChanged(m_testEnum);}
+signals:
+    void testEnumChanged(ObjectA::TestEnum testEnum);
+private:
+    ObjectA::TestEnum m_testEnum = ObjectA::Default;
+};
+
+class ObjectC : public ObjectB
+{
+    Q_OBJECT
+
+public:
+    ObjectC() = default;
+};
+
+void tst_qqmllanguage::enumNoScopeLeak()
+{
+    qmlRegisterType<ObjectA>("test", 1, 0, "ObjectA");
+    qmlRegisterType<ObjectB>("test", 1, 0, "ObjectB");
+    qmlRegisterType<ObjectC>("test", 1, 0, "ObjectC");
+    QQmlEngine engine;
+    auto url = testFileUrl("enumScopeLeak.qml");
+    QQmlComponent component(&engine, url);
+    const auto msg = url.toString() + ":5:5: Unable to assign [undefined] to ObjectA::TestEnum";
+    QTest::ignoreMessage(QtMsgType::QtWarningMsg, msg.toUtf8().constData());
+    QScopedPointer<QObject> root(component.create());
+    QVERIFY(root);
+    QCOMPARE(root->property("testEnum").toInt(), ObjectA::Default);
+}
+
 void tst_qqmllanguage::qmlEnums()
 {
     QQmlEngine engine;