Fix wrong generation of Q_NAMESPACES

Generate Q_NAMESPACE if foreign type is a namespace.
Add compilation test for this only.

Fixes: QTBUG-123535
Pick-to: 6.5
Change-Id: Iacce6681a3fba468c1a9646630c871e2553d56bd
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
(cherry picked from commit f080d0309d4c1d0d8a96dabe832162c5f41b881f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 4b1704b8e050755de7b86ab0f1b0dd262ca98982)

4 files changed, 50 insertions, 3 deletions

diff --git a/src/qmltyperegistrar/qmetatypesjsonprocessor.cpp b/src/qmltyperegistrar/qmetatypesjsonprocessor.cpp
index 5bbd878779..df360bc44e 100644
--- a/src/qmltyperegistrar/qmetatypesjsonprocessor.cpp
+++ b/src/qmltyperegistrar/qmetatypesjsonprocessor.cpp
@@ -135,6 +135,7 @@ QString MetaTypesJsonProcessor::extractRegisteredTypes() const
         QString qmlAttached;
         bool isSingleton = false;
         bool isExplicitlyUncreatable = false;
+        bool isNamespace = obj[u"namespace"].toBool();
         for (QJsonValue entry: classInfos) {
             const auto name = entry[u"name"].toString();
             const auto value = entry[u"value"].toString();
@@ -159,8 +160,13 @@ QString MetaTypesJsonProcessor::extractRegisteredTypes() const
         if (qmlElement.isEmpty())
             continue; // no relevant entries found
         const QString spaces = u"    "_s;
-        registrationHelper += u"\nstruct "_s + foreignClassName + u"{\n    Q_GADGET\n"_s;
-        registrationHelper += spaces + u"QML_FOREIGN(" + className + u")\n"_s;
+        if (isNamespace) {
+            registrationHelper += u"\nnamespace "_s + foreignClassName + u"{\n    Q_NAMESPACE\n"_s;
+            registrationHelper += spaces + u"QML_FOREIGN_NAMESPACE(" + className + u")\n"_s;
+        } else {
+            registrationHelper += u"\nstruct "_s + foreignClassName + u"{\n    Q_GADGET\n"_s;
+            registrationHelper += spaces + u"QML_FOREIGN(" + className + u")\n"_s;
+        }
         registrationHelper += spaces + qmlElement + u"\n"_s;
         if (isSingleton)
             registrationHelper += spaces + u"QML_SINGLETON\n"_s;
@@ -172,7 +178,10 @@ QString MetaTypesJsonProcessor::extractRegisteredTypes() const
         }
         if (!qmlAttached.isEmpty())
             registrationHelper += spaces + qmlAttached + u"\n";
-        registrationHelper += u"};\n";
+        registrationHelper += u"}";
+        if (!isNamespace)
+            registrationHelper += u";";
+        registrationHelper += u"\n";
     }
     return registrationHelper;
 }
diff --git a/tests/auto/qml/qmltyperegistrar/CMakeLists.txt b/tests/auto/qml/qmltyperegistrar/CMakeLists.txt
index a0d26b733a..fadde11c95 100644
--- a/tests/auto/qml/qmltyperegistrar/CMakeLists.txt
+++ b/tests/auto/qml/qmltyperegistrar/CMakeLists.txt
@@ -93,3 +93,17 @@ qt_internal_add_resource(tst_qmltyperegistrar "resources"
     FILES
         duplicatedExports.json
 )
+
+set(CMAKE_INCLUDE_CURRENT_DIR ON)
+qt_add_library(tst-qmltyperegistrar-enum-foreign STATIC enum.cpp)
+qt_autogen_tools_initial_setup(tst-qmltyperegistrar-enum-foreign)
+qt_enable_autogen_tool(tst-qmltyperegistrar-enum-foreign "moc" ON)
+target_link_libraries(tst-qmltyperegistrar-enum-foreign PRIVATE Qt::QmlIntegration)
+
+qt_add_library(tst-qmltyperegistrar-enum STATIC)
+qt_autogen_tools_initial_setup(tst-qmltyperegistrar-enum)
+qt_enable_autogen_tool(tst-qmltyperegistrar-enum "moc" ON)
+target_link_libraries(tst-qmltyperegistrar-enum PRIVATE Qt::Qml tst-qmltyperegistrar-enum-foreign)
+
+qt_add_qml_module(tst-qmltyperegistrar-enum URI TstEnum OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/TstEnum)
+qt_generate_foreign_qml_types(tst-qmltyperegistrar-enum-foreign tst-qmltyperegistrar-enum)
diff --git a/tests/auto/qml/qmltyperegistrar/enum.cpp b/tests/auto/qml/qmltyperegistrar/enum.cpp
new file mode 100644
index 0000000000..34d2e00ffa
--- /dev/null
+++ b/tests/auto/qml/qmltyperegistrar/enum.cpp
@@ -0,0 +1,5 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include "enum.h"
+#include "moc_enum.cpp"
diff --git a/tests/auto/qml/qmltyperegistrar/enum.h b/tests/auto/qml/qmltyperegistrar/enum.h
new file mode 100644
index 0000000000..4a39c22545
--- /dev/null
+++ b/tests/auto/qml/qmltyperegistrar/enum.h
@@ -0,0 +1,19 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#ifndef ENUM_NS_HELLO_H
+#define ENUM_NS_HELLO_H
+
+#include <QObject>
+#include <QtQmlIntegration/qqmlintegration.h>
+
+namespace Hello {
+    Q_NAMESPACE
+    QML_NAMED_ELEMENT(World)
+    enum class World {
+        Europe = 2024,
+    };
+    Q_ENUM_NS(World)
+}
+
+#endif // ENUM_NS_HELLO_H