QtXml: be systematic about feature dom

All the actual code of the module was subject to #ifndef QT_NO_DOM,
aside from the *_p.h that were only included subject to such #if-ery,
so there's nothing left of the module if the feature is ever disabled,
but be consistent with the module defining a feature that allows that.
Convert #ifndef QT_NO_DOM to #if QT_CONFIG(dom) (and move to outside
the namespace, where nothing was inside without the define), require
feature dom in the *_p.h and test, change CMake config to skip the
test when the feature is disabled (and add a missing SPDX comment),
condition including sources on the feature.

Pick-to: 6.7 6.5
Task-number: QTBUG-122619
Change-Id: Ie2167b6c56d96c7804785e225f3fe02dbc78984c
Reviewed-by:  Alexey Edelev <alexey.edelev@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit a4c85a5cf19d8919797aba41077bfa8796427f54)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/xml/CMakeLists.txt

@@ -7,8 +7,6 @@
 
 qt_internal_add_module(Xml
     SOURCES
-        dom/qdom.cpp dom/qdom.h dom/qdom_p.h
-        dom/qdomhelpers.cpp dom/qdomhelpers_p.h
         qtxmlglobal.h
     DEFINES
         QT_NO_CONTEXTLESS_CONNECT
@@ -23,13 +21,17 @@ qt_internal_add_module(Xml
         Qt::CorePrivate
 )
 
-## Scopes:
+qt_internal_extend_target(Xml CONDITION QT_FEATURE_dom
-#####################################################################
+    SOURCES
+        dom/qdom.cpp dom/qdom.h dom/qdom_p.h
+        dom/qdomhelpers.cpp dom/qdomhelpers_p.h
+)
 
 qt_internal_extend_target(Xml CONDITION MSVC AND (TEST_architecture_arch STREQUAL "i386")
     LINK_OPTIONS
         "/BASE:0x61000000"
 )
+
 qt_internal_add_docs(Xml
     doc/qtxml.qdocconf
 )

src/xml/dom/qdom.cpp

@@ -5,7 +5,7 @@
 #include <qdom.h>
 #include "private/qxmlutils_p.h"
 
-#ifndef QT_NO_DOM
+#if QT_CONFIG(dom)
 
 #include "qdom_p.h"
 #include "qdomhelpers_p.h"
@@ -6983,4 +6983,4 @@ QDomComment QDomNode::toComment() const
 
 QT_END_NAMESPACE
 
-#endif // QT_NO_DOM
+#endif // feature dom

src/xml/dom/qdom.h

@@ -7,13 +7,12 @@
 #include <QtXml/qtxmlglobal.h>
 #include <QtCore/qstring.h>
 
+#if QT_CONFIG(dom)
+
 class tst_QDom;
 
 QT_BEGIN_NAMESPACE
 
-
-#ifndef QT_NO_DOM
-
 class QIODevice;
 class QTextStream;
 
@@ -666,8 +665,8 @@ private:
 
 Q_XML_EXPORT QTextStream& operator<<(QTextStream& stream, const QDomNode& node);
 
-#endif // QT_NO_DOM
-
 QT_END_NAMESPACE
 
+#endif // feature dom
+
 #endif // QDOM_H

src/xml/dom/qdom_p.h

@@ -11,6 +11,7 @@
 #include <qlist.h>
 #include <qshareddata.h>
 
+QT_REQUIRE_CONFIG(dom);
 QT_BEGIN_NAMESPACE
 
 //

src/xml/dom/qdomhelpers.cpp

@@ -3,7 +3,7 @@
 
 #include <QtXml/qtxmlglobal.h>
 
-#ifndef QT_NO_DOM
+#if QT_CONFIG(dom)
 
 #include "qdomhelpers_p.h"
 #include "qdom_p.h"
@@ -442,4 +442,4 @@ bool QDomParser::parseMarkupDecl()
 
 QT_END_NAMESPACE
 
-#endif // QT_NO_DOM
+#endif // feature dom

src/xml/dom/qdomhelpers_p.h

@@ -7,6 +7,7 @@
 #include <qdom.h>
 #include <private/qglobal_p.h>
 
+QT_REQUIRE_CONFIG(dom);
 QT_BEGIN_NAMESPACE
 
 //

tests/auto/xml/CMakeLists.txt

@@ -1,3 +1,6 @@
 # Copyright (C) 2024 The Qt Company Ltd.
 # SPDX-License-Identifier: BSD-3-Clause
-add_subdirectory(dom)
+
+if(QT_FEATURE_dom)
+    add_subdirectory(dom)
+endif()

tests/auto/xml/dom/qdom/tst_qdom.cpp

@@ -17,6 +17,7 @@
 #include <cmath>
 #include <QtXml/private/qdom_p.h>
 
+QT_REQUIRE_CONFIG(dom);
 QT_FORWARD_DECLARE_CLASS(QDomDocument)
 QT_FORWARD_DECLARE_CLASS(QDomNode)