QMetaObjectBuilder: Fix construction logic for enums

We need to put metatypes in the correct place; this is especially vital
starting with Qt 6.9, given that we need it to query it to figure out
whether we have a 64bit value or not.

As a drive-by, replace some ugly casting when constructing the meta-type
array with a call to QMetaType::iface.

Pick-to: 6.8
Change-Id: I4b1f42f974e9f7a21f6aa4c87c3f8919f6965d6e
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/corelib/kernel/qmetaobjectbuilder.cpp

@@ -1253,8 +1253,8 @@ static int buildMetaObject(QMetaObjectBuilderPrivate *d, char *buf,
 
     // Output the methods in the class.
     Q_ASSERT(!buf || dataIndex == pmeta->methodData);
-    // + 1 for metatype of this metaobject
-    int parameterMetaTypesIndex = int(d->properties.size()) + 1;
+    // property count + enum count  + 1 for metatype of this metaobject
+    int parameterMetaTypesIndex = int(d->properties.size()) + int(d->enumerators.size()) + 1;
     for (const auto &method : d->methods) {
         [[maybe_unused]] int name = strings.enter(method.name());
         int argc = method.parameterCount();
@@ -1418,12 +1418,19 @@ static int buildMetaObject(QMetaObjectBuilderPrivate *d, char *buf,
     }
 
     ALIGN(size, QtPrivate::QMetaTypeInterface *);
-    auto types = reinterpret_cast<QtPrivate::QMetaTypeInterface **>(buf + size);
+    auto types = reinterpret_cast<const QtPrivate::QMetaTypeInterface **>(buf + size);
     if constexpr (mode == Construct) {
         meta->d.metaTypes = types;
         for (const auto &prop : d->properties) {
             QMetaType mt = prop.metaType;
-            *types = reinterpret_cast<QtPrivate::QMetaTypeInterface *&>(mt);
+            *types = mt.iface();
+            types++;
+        }
+        // add metatypes for enumerators
+        for (const auto &enumerator: d->enumerators) {
+            QMetaType mt = enumerator.metaType;
+            mt.registerType();
+            *types = mt.iface();
             types++;
         }
         // add metatype interface for this metaobject - must be null
@@ -1436,14 +1443,14 @@ static int buildMetaObject(QMetaObjectBuilderPrivate *d, char *buf,
             types++;
             for (const auto &parameterType: method.parameterTypes()) {
                 QMetaType mt = QMetaType::fromName(parameterType);
-                *types = reinterpret_cast<QtPrivate::QMetaTypeInterface *&>(mt);
+                *types = mt.iface();
                 types++;
             }
         }
         for (const auto &constructor : d->constructors) {
             for (const auto &parameterType : constructor.parameterTypes()) {
                 QMetaType mt = QMetaType::fromName(parameterType);
-                *types = reinterpret_cast<QtPrivate::QMetaTypeInterface *&>(mt);
+                *types = mt.iface();
                 types++;
             }
         }

tests/auto/corelib/kernel/qmetaobjectbuilder/tst_qmetaobjectbuilder.cpp

@@ -39,6 +39,7 @@ private slots:
     void classNameFirstInStringData();
 
     void propertyMetaType();
+    void enumCloning();
 
     void cleanupTestCase();
 
@@ -1713,6 +1714,26 @@ void tst_QMetaObjectBuilder::propertyMetaType()
     free(mo);
 }
 
+void tst_QMetaObjectBuilder::enumCloning()
+{
+    QMetaObjectBuilder builder(&SomethingOfEverything::staticMetaObject);
+    auto smo = SomethingOfEverything::staticMetaObject;
+    auto mo = builder.toMetaObject();
+    auto cleanup = qScopeGuard([&]() { free(mo); });
+    QCOMPARE_EQ(mo->enumeratorCount(), smo.enumeratorCount());
+    for (int enumIndex = 0; enumIndex <  smo.enumeratorCount(); ++enumIndex) {
+        QMetaEnum metaEnumFromBuilder = mo->enumerator(enumIndex);
+        QMetaEnum originalMetaEnum = smo.enumerator(enumIndex);
+        QCOMPARE_EQ(metaEnumFromBuilder.metaType(), originalMetaEnum.metaType());
+        QCOMPARE_EQ(metaEnumFromBuilder.keyCount(), originalMetaEnum.keyCount());
+        for (int k = 0; k < originalMetaEnum.keyCount(); ++k) {
+            QCOMPARE_EQ(QByteArrayView(metaEnumFromBuilder.key(k)), QByteArrayView(originalMetaEnum.key(k)));
+            QCOMPARE_EQ(metaEnumFromBuilder.value(k), originalMetaEnum.value(k));
+            QCOMPARE_EQ(metaEnumFromBuilder.value64(k), originalMetaEnum.value64(k));
+        }
+    }
+}
+
 void tst_QMetaObjectBuilder::ownMetaTypeNoProperties()
 {
     QMetaObjectBuilder builder;