Fix enum class lookup on Singletons

When we consolidated the code for looking up enums in QQmlType,
we exposed ourselves to a bug in initEnums: Not only CppType should be
affected by the logic for registering unscoped enums, but also C++
singletons (SingletonType).
Amends 4ceb343e7f006972940b6880f974770c02fa6b87 and
4e69f2468ad599b7175f60e08341d37689512c9c.

Fix this by consulting the meatobject, if there is one. Ideally, this
should probably stored in the QQmlType at type registration time, but
that can be cleaned up at a later point.

Fixes: QTBUG-123225
Task-number: QTBUG-123294
Pick-to: 6.7.0
Change-Id: I7b09459ce4035acb2566b9550fa844897b1b363a
Reviewed-by: Sami Shalayel <sami.shalayel@qt.io>
(cherry picked from commit 9d19d7e6e3bc28a0a62cebb01a0a562b1c13d12f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 18 insertions, 2 deletions

diff --git a/src/qml/qml/qqmltype.cpp b/src/qml/qml/qqmltype.cpp
index ee5ae374e5..782d55980f 100644
--- a/src/qml/qml/qqmltype.cpp
+++ b/src/qml/qml/qqmltype.cpp
@@ -302,6 +302,19 @@ void QQmlTypePrivate::insertEnums(Enums *enums, const QMetaObject *metaObject) c
     QSet<QString> localEnums;
     const QMetaObject *localMetaObject = nullptr;
 
+    // ### TODO (QTBUG-123294): track this at instance creation time
+    auto shouldSingletonAlsoRegisterUnscoped = [&](){
+        Q_ASSERT(regType == QQmlType::SingletonType);
+        if (!baseMetaObject)
+            return true;
+        int idx = baseMetaObject->indexOfClassInfo("RegisterEnumClassesUnscoped");
+        if (idx == -1)
+            return true;
+        if (qstrcmp(baseMetaObject->classInfo(idx).value(), "false") == 0)
+            return false;
+        return true;
+    };
+
     // Add any enum values defined by this class, overwriting any inherited values
     for (int ii = 0; ii < metaObject->enumeratorCount(); ++ii) {
         QMetaEnum e = metaObject->enumerator(ii);
@@ -318,12 +331,15 @@ void QQmlTypePrivate::insertEnums(Enums *enums, const QMetaObject *metaObject) c
             localEnums.clear();
             localMetaObject = e.enclosingMetaObject();
         }
+        const bool shouldRegisterUnscoped = !isScoped
+                || (regType == QQmlType::CppType && extraData.cppTypeData->registerEnumClassesUnscoped)
+                || (regType == QQmlType::SingletonType && shouldSingletonAlsoRegisterUnscoped())
+        ;
 
         for (int jj = 0; jj < e.keyCount(); ++jj) {
             const QString key = QString::fromUtf8(e.key(jj));
             const int value = e.value(jj);
-            if (!isScoped || (regType == QQmlType::CppType
-                              && extraData.cppTypeData->registerEnumClassesUnscoped)) {
+            if (shouldRegisterUnscoped) {
                 if (localEnums.contains(key)) {
                     auto existingEntry = enums->enums.find(key);
                     if (existingEntry != enums->enums.end() && existingEntry.value() != value) {