moc: move some of the helpers into a header dedicated to it

Change-Id: Id0fb9ab0089845ee8843fffd16f9d080029f2f7f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/corelib/CMakeLists.txt

@@ -141,7 +141,7 @@ qt_internal_add_module(Core
         kernel/qmetaobjectbuilder.cpp kernel/qmetaobjectbuilder_p.h
         kernel/qmetatype.cpp kernel/qmetatype.h kernel/qmetatype_p.h
         kernel/qmimedata.cpp kernel/qmimedata.h
-        kernel/qtmetamacros.h
+        kernel/qtmetamacros.h kernel/qtmochelpers.h
         kernel/qobject.cpp kernel/qobject.h kernel/qobject_p.h kernel/qobject_p_p.h
         kernel/qobject_impl.h
         kernel/qobjectcleanuphandler.cpp kernel/qobjectcleanuphandler.h

src/corelib/global/qtnamespacemacros.h

@@ -25,12 +25,6 @@
 # define QT_END_NAMESPACE
 # define QT_BEGIN_INCLUDE_NAMESPACE
 # define QT_END_INCLUDE_NAMESPACE
-#ifndef QT_BEGIN_MOC_NAMESPACE
-# define QT_BEGIN_MOC_NAMESPACE
-#endif
-#ifndef QT_END_MOC_NAMESPACE
-# define QT_END_MOC_NAMESPACE
-#endif
 # define QT_FORWARD_DECLARE_CLASS(name) class name;
 # define QT_FORWARD_DECLARE_STRUCT(name) struct name;
 
@@ -42,12 +36,6 @@
 # define QT_END_NAMESPACE }
 # define QT_BEGIN_INCLUDE_NAMESPACE }
 # define QT_END_INCLUDE_NAMESPACE namespace QT_NAMESPACE {
-#ifndef QT_BEGIN_MOC_NAMESPACE
-# define QT_BEGIN_MOC_NAMESPACE QT_USE_NAMESPACE
-#endif
-#ifndef QT_END_MOC_NAMESPACE
-# define QT_END_MOC_NAMESPACE
-#endif
 # define QT_FORWARD_DECLARE_CLASS(name) \
     QT_BEGIN_NAMESPACE class name; QT_END_NAMESPACE \
     using QT_PREPEND_NAMESPACE(name);
@@ -82,6 +70,14 @@ namespace QT_NAMESPACE {}
 
 #endif /* __cplusplus */
 
+/* ### Qt 6.9 (or later): remove *_MOC_* macros (moc does not need them since 6.5) */
+#ifndef QT_BEGIN_MOC_NAMESPACE
+# define QT_BEGIN_MOC_NAMESPACE QT_USE_NAMESPACE
+#endif
+#ifndef QT_END_MOC_NAMESPACE
+# define QT_END_MOC_NAMESPACE
+#endif
+
 /* silence syncqt warning */
 QT_BEGIN_NAMESPACE
 QT_END_NAMESPACE

src/corelib/kernel/qtmochelpers.h

@@ -0,0 +1,32 @@
+// Copyright (C) 2022 Intel Corporation.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QTMOCHELPERS_H
+#define QTMOCHELPERS_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. It exists to be used by the code that
+// moc generates. This file will not change quickly, but it over the long term,
+// it will likely change or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+
+#if 0
+#pragma qt_no_master_include
+#endif
+
+QT_BEGIN_NAMESPACE
+namespace QtMocHelpers {
+
+} // namespace QtMocHelpers
+QT_END_NAMESPACE
+
+QT_USE_NAMESPACE
+
+#endif // QTMOCHELPERS_H

src/tools/moc/moc.cpp

@@ -1091,6 +1091,16 @@ void Moc::generate(FILE *out, FILE *jsonOutput)
     for (const QByteArray &qtContainer : qtContainers)
         fprintf(out, "#include <QtCore/%s>\n", qtContainer.constData());
 
+    fprintf(out, "\n%s#include <QtCore/qtmochelpers.h>\n%s\n",
+#if QT_VERSION <= QT_VERSION_CHECK(6, 9, 0)
+            "#if __has_include(<QtCore/qtmochelpers.h>)\n",
+            "#else\n"
+            "QT_BEGIN_MOC_NAMESPACE\n"
+            "#endif\n"
+#else
+            "", ""
+#endif
+    );
 
     fprintf(out, "#if !defined(Q_MOC_OUTPUT_REVISION)\n"
             "#error \"The header file '%s' doesn't include <QObject>.\"\n", fn.constData());
@@ -1107,7 +1117,6 @@ void Moc::generate(FILE *out, FILE *jsonOutput)
             "#endif\n\n");
 #endif
 
-    fprintf(out, "QT_BEGIN_MOC_NAMESPACE\n");
     fprintf(out, "QT_WARNING_PUSH\n");
     fprintf(out, "QT_WARNING_DISABLE_DEPRECATED\n");
     fprintf(out, "QT_WARNING_DISABLE_GCC(\"-Wuseless-cast\")\n");
@@ -1120,7 +1129,6 @@ void Moc::generate(FILE *out, FILE *jsonOutput)
     fputs("", out);
 
     fprintf(out, "QT_WARNING_POP\n");
-    fprintf(out, "QT_END_MOC_NAMESPACE\n");
 
     if (jsonOutput) {
         QJsonObject mocData;