14 files changed, 457 insertions, 92 deletions
diff --git a/sources/shiboken6/ApiExtractor/CMakeLists.txt b/sources/shiboken6/ApiExtractor/CMakeLists.txt
index 48bc3abbc..494881464 100644
--- a/sources/shiboken6/ApiExtractor/CMakeLists.txt
+++ b/sources/shiboken6/ApiExtractor/CMakeLists.txt
@@ -15,6 +15,7 @@ abstractmetafield.cpp
 abstractmetafunction.cpp
 abstractmetatype.cpp
 abstractmetalang.cpp
+conditionalstreamreader.cpp
 documentation.cpp
 enclosingclassmixin.cpp
 fileout.cpp
diff --git a/sources/shiboken6/ApiExtractor/apiextractor.cpp b/sources/shiboken6/ApiExtractor/apiextractor.cpp
index f91844126..cee8bbdcd 100644
--- a/sources/shiboken6/ApiExtractor/apiextractor.cpp
+++ b/sources/shiboken6/ApiExtractor/apiextractor.cpp
@@ -72,6 +72,11 @@ void ApiExtractor::addTypesystemSearchPath(const QStringList& paths)
         addTypesystemSearchPath(path);
 }
 
+void ApiExtractor::setTypesystemKeywords(const QStringList &keywords)
+{
+    TypeDatabase::instance()->setTypesystemKeywords(keywords);
+}
+
 void ApiExtractor::addIncludePath(const HeaderPath& path)
 {
     m_includePaths << path;
diff --git a/sources/shiboken6/ApiExtractor/apiextractor.h b/sources/shiboken6/ApiExtractor/apiextractor.h
index c0788462f..f7e3685f5 100644
--- a/sources/shiboken6/ApiExtractor/apiextractor.h
+++ b/sources/shiboken6/ApiExtractor/apiextractor.h
@@ -73,6 +73,7 @@ public:
     static void setSilent(bool value);
     static void addTypesystemSearchPath(const QString &path);
     static void addTypesystemSearchPath(const QStringList& paths);
+    static void setTypesystemKeywords(const QStringList& keywords);
     void addIncludePath(const HeaderPath& path);
     void addIncludePath(const HeaderPaths& paths);
     HeaderPaths includePaths() const { return m_includePaths; }
diff --git a/sources/shiboken6/ApiExtractor/conditionalstreamreader.cpp b/sources/shiboken6/ApiExtractor/conditionalstreamreader.cpp
new file mode 100644
index 000000000..2380ee892
--- /dev/null
+++ b/sources/shiboken6/ApiExtractor/conditionalstreamreader.cpp
@@ -0,0 +1,122 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "conditionalstreamreader.h"
+
+#include <QtCore/QDebug>
+
+QXmlStreamReader::TokenType ConditionalStreamReader::readNext()
+{
+    auto exToken = readNextInternal();
+    if (exToken.second != PiTokens::If || conditionMatches())
+        return exToken.first;
+
+    // Condition does not match - search for endif
+    int nestingLevel = 1;
+    while (true) {
+        exToken = readNextInternal();
+        if (exToken.first == QXmlStreamReader::NoToken
+            || exToken.first == QXmlStreamReader::Invalid
+            || exToken.first == QXmlStreamReader::EndDocument) {
+            break;
+        }
+
+        if (exToken.second == PiTokens::If)
+            ++nestingLevel;
+        else if (exToken.second == PiTokens::Endif && --nestingLevel == 0)
+            break;
+    }
+    return exToken.first;
+}
+
+bool ConditionalStreamReader::conditionMatches() const
+{
+    const auto keywords = m_reader.processingInstructionData().split(u' ', Qt::SkipEmptyParts);
+
+    bool matches = false;
+    for (const auto &keyword : keywords) {
+        if (keyword.startsWith(u'!')) { // exclusion '!windows' takes preference
+            if (m_conditions.contains(keyword.mid(1)))
+                return false;
+        } else {
+            matches |= m_conditions.contains(keyword);
+        }
+    }
+    return matches;
+}
+
+void ConditionalStreamReader::setConditions(const QStringList &newConditions)
+{
+    m_conditions = newConditions + platformConditions();
+}
+
+QStringList ConditionalStreamReader::platformConditions()
+{
+    QStringList result;
+#if defined (Q_OS_UNIX)
+    result << QStringLiteral("unix");
+#endif
+
+#if defined (Q_OS_LINUX)
+    result << QStringLiteral("linux");
+#elif defined (Q_OS_MACOS)
+    result << QStringLiteral("darwin");
+#elif defined (Q_OS_WINDOWS)
+    result << QStringLiteral("windows");
+#endif
+    return result;
+}
+
+ConditionalStreamReader::ExtendedToken ConditionalStreamReader::readNextInternal()
+{
+    const auto token = m_reader.readNext();
+    PiTokens piToken = PiTokens::None;
+    if (token == QXmlStreamReader::ProcessingInstruction) {
+        const auto target = m_reader.processingInstructionTarget();
+        if (target == u"if")
+            piToken = PiTokens::If;
+        else if (target == u"endif")
+            piToken = PiTokens::Endif;
+    }
+    return {token, piToken};
+}
+
+QDebug operator<<(QDebug dbg, const QXmlStreamAttributes &attrs)
+{
+    QDebugStateSaver saver(dbg);
+    dbg.noquote();
+    dbg.nospace();
+    dbg << "QXmlStreamAttributes(";
+    for (qsizetype i = 0, size = attrs.size(); i < size; ++i ) {
+        if (i)
+            dbg << ", ";
+        dbg << attrs.at(i).name() << "=\"" << attrs.at(i).value() << '"';
+    }
+    dbg << ')';
+    return dbg;
+}
diff --git a/sources/shiboken6/ApiExtractor/conditionalstreamreader.h b/sources/shiboken6/ApiExtractor/conditionalstreamreader.h
new file mode 100644
index 000000000..691c5e21d
--- /dev/null
+++ b/sources/shiboken6/ApiExtractor/conditionalstreamreader.h
@@ -0,0 +1,100 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt for Python.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef CONDITIONALSTREAMREADER_H
+#define CONDITIONALSTREAMREADER_H
+
+#include <QtCore/QXmlStreamReader>
+
+#include <utility>
+
+QT_FORWARD_DECLARE_CLASS(QDebug)
+
+/// ConditionalStreamReader encapsulates QXmlStreamReader, offering the same
+/// API (except readNextStartElement() and similar conveniences) and internally
+/// uses Processing Instructions like:
+///   <?if keyword1 !keyword2?> ... <?endif?>
+/// to exclude/include sections depending on a list of condition keywords,
+/// containing for example the OS.
+/// It should be possible to use it as a drop-in replacement for
+/// QXmlStreamReader for any parsing code based on readNext().
+class ConditionalStreamReader
+{
+public:
+    using TokenType = QXmlStreamReader::TokenType;
+    explicit ConditionalStreamReader(QIODevice *iod) : m_reader(iod) { }
+    explicit ConditionalStreamReader(const QString &s) : m_reader(s) { }
+
+    QIODevice *device() const { return m_reader.device(); }
+
+    void setEntityResolver(QXmlStreamEntityResolver *resolver) { m_reader.setEntityResolver(resolver); }
+    QXmlStreamEntityResolver *entityResolver() const { return m_reader.entityResolver(); }
+
+    bool atEnd() const { return m_reader.atEnd(); }
+    TokenType readNext();
+
+    TokenType tokenType() const { return  m_reader.tokenType(); }
+
+    qint64 lineNumber() const { return m_reader.lineNumber(); }
+    qint64 columnNumber() const { return m_reader.columnNumber(); }
+
+    QXmlStreamAttributes attributes() const { return m_reader.attributes(); }
+
+    QString readElementText(QXmlStreamReader::ReadElementTextBehaviour behaviour = QXmlStreamReader::ErrorOnUnexpectedElement)
+    { return m_reader.readElementText(behaviour); }
+
+    QStringView name() const { return m_reader.name(); }
+    QStringView qualifiedName() const { return m_reader.qualifiedName(); }
+
+    QStringView text() const { return m_reader.text(); }
+
+    QString errorString() const { return m_reader.errorString(); }
+    QXmlStreamReader::Error error() const { return m_reader.error(); }
+
+    bool hasError() const { return m_reader.hasError(); }
+
+    const QStringList &conditions() const { return m_conditions; }
+    void setConditions(const QStringList &newConditions);
+
+    static QStringList platformConditions();
+
+private:
+    enum class PiTokens { None, If, Endif };
+
+    using ExtendedToken = std::pair<TokenType, PiTokens>;
+    ExtendedToken readNextInternal();
+
+    bool conditionMatches() const;
+
+    QXmlStreamReader m_reader;
+    QStringList m_conditions = ConditionalStreamReader::platformConditions();
+};
+
+QDebug operator<<(QDebug dbg, const QXmlStreamAttributes &a);
+
+#endif // CONDITIONALSTREAMREADER_H
diff --git a/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.cpp b/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.cpp
index c47c7232f..1b03f9353 100644
--- a/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.cpp
+++ b/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.cpp
@@ -32,6 +32,7 @@
 #include <abstractmetaenum.h>
 #include <abstractmetalang.h>
 #include <typesystem.h>
+#include <conditionalstreamreader.h>
 
 static const char* cppCode ="\
     struct ValueA {};\n\
@@ -146,4 +147,75 @@ void TestDropTypeEntries::testDontDropEntryWithChildTags()
     QVERIFY(AbstractMetaClass::findClass(builder->classes(), QLatin1String("ValueA")));
 }
 
+void TestDropTypeEntries::testConditionalParsing_data()
+{
+    const QString xml = QStringLiteral(R"(<?xml version="1.0" encoding="UTF-8"?>
+<root>
+    <tag1>text</tag1>
+    <?if keyword1?>
+        <tag2>text</tag2>
+        <?if keyword2?>
+            <tag3>text</tag3>
+        <?endif?>
+        <?if keyword1 !keyword2?>
+            <tag4>text</tag4>
+        <?endif?>
+    <?endif?>
+    <tag5>text</tag5>
+</root>)");
+
+    const QString root = QStringLiteral("root");
+    const QString tag1 = QStringLiteral("tag1");
+    const QString tag2 = QStringLiteral("tag2");
+    const QString tag3 = QStringLiteral("tag3");
+    const QString tag4 = QStringLiteral("tag4");
+    const QString tag5 = QStringLiteral("tag5");
+    const QString keyword1 = QStringLiteral("keyword1");
+    const QString keyword2 = QStringLiteral("keyword2");
+
+    QTest::addColumn<QString>("xml");
+    QTest::addColumn<QStringList>("keywords");
+    QTest::addColumn<QStringList>("expectedTags");
+
+    QTest::newRow("no-keywords")
+        << xml << QStringList{} << QStringList{root, tag1, tag5};
+
+    QTest::newRow("skip-nested-condition")
+        << xml << QStringList{keyword1}
+        << QStringList{root, tag1, tag2, tag4, tag5};
+
+    QTest::newRow("both/check-not")
+        << xml << QStringList{keyword1, keyword2}
+        << QStringList{root, tag1, tag2, tag3, tag5};
+}
+
+// Parse XML and return a list of tags encountered
+static QStringList parseXml(const QString &xml, const QStringList &keywords)
+{
+    QStringList tags;
+    ConditionalStreamReader reader(xml);
+    reader.setConditions(keywords);
+    while (!reader.atEnd()) {
+        auto t = reader.readNext();
+        switch (t) {
+        case QXmlStreamReader::StartElement:
+            tags.append(reader.name().toString());
+            break;
+        default:
+            break;
+        }
+    }
+    return tags;
+}
+
+void TestDropTypeEntries::testConditionalParsing()
+{
+    QFETCH(QString, xml);
+    QFETCH(QStringList, keywords);
+    QFETCH(QStringList, expectedTags);
+
+    const QStringList actualTags = parseXml(xml, keywords);
+    QCOMPARE(actualTags, expectedTags);
+}
+
 QTEST_APPLESS_MAIN(TestDropTypeEntries)
diff --git a/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.h b/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.h
index 3023a1120..7746234ba 100644
--- a/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.h
+++ b/sources/shiboken6/ApiExtractor/tests/testdroptypeentries.h
@@ -39,6 +39,8 @@ class TestDropTypeEntries : public QObject
         void testDontDropEntries();
         void testDropEntryWithChildTags();
         void testDontDropEntryWithChildTags();
+        void testConditionalParsing_data();
+        void testConditionalParsing();
 };
 
 #endif
diff --git a/sources/shiboken6/ApiExtractor/typedatabase.cpp b/sources/shiboken6/ApiExtractor/typedatabase.cpp
index f7399fe6d..8a4e6d2f1 100644
--- a/sources/shiboken6/ApiExtractor/typedatabase.cpp
+++ b/sources/shiboken6/ApiExtractor/typedatabase.cpp
@@ -29,6 +29,7 @@
 #include "typedatabase.h"
 #include "typesystem.h"
 #include "typesystemparser.h"
+#include "conditionalstreamreader.h"
 
 #include <QtCore/QFile>
 #include <QtCore/QDebug>
@@ -138,6 +139,14 @@ void TypeDatabase::addTypesystemPath(const QString& typesystem_paths)
     m_typesystemPaths += typesystem_paths.split(QLatin1Char(path_splitter));
 }
 
+QStringList TypeDatabase::typesystemKeywords() const
+{
+    QStringList result = m_typesystemKeywords;
+    for (const auto &d : m_dropTypeEntries)
+        result.append(QStringLiteral("no_") + d);
+    return result;
+}
+
 IncludeList TypeDatabase::extraIncludes(const QString& className) const
 {
     ComplexTypeEntry* typeEntry = findComplexType(className);
@@ -634,7 +643,8 @@ bool TypeDatabase::parseFile(const QString &filename, const QString &currentPath
 
 bool TypeDatabase::parseFile(QIODevice* device, bool generate)
 {
-    QXmlStreamReader reader(device);
+    ConditionalStreamReader reader(device);
+    reader.setConditions(TypeDatabase::instance()->typesystemKeywords());
     TypeSystemParser handler(this, generate);
     const bool result = handler.parse(reader);
     if (!result)
diff --git a/sources/shiboken6/ApiExtractor/typedatabase.h b/sources/shiboken6/ApiExtractor/typedatabase.h
index c49addb3e..082d833b5 100644
--- a/sources/shiboken6/ApiExtractor/typedatabase.h
+++ b/sources/shiboken6/ApiExtractor/typedatabase.h
@@ -114,6 +114,9 @@ public:
 
     void addTypesystemPath(const QString &typesystem_paths);
 
+    void setTypesystemKeywords(const QStringList &keywords) { m_typesystemKeywords = keywords; }
+    QStringList typesystemKeywords() const;
+
     IncludeList extraIncludes(const QString &className) const;
 
     const QByteArrayList &systemIncludes() const { return m_systemIncludes; }
@@ -229,6 +232,7 @@ private:
     QStringList m_requiredTargetImports;
 
     QStringList m_typesystemPaths;
+    QStringList m_typesystemKeywords;
     QHash<QString, bool> m_parsedTypesystemFiles;
 
     QList<TypeRejection> m_rejections;
diff --git a/sources/shiboken6/ApiExtractor/typesystemparser.cpp b/sources/shiboken6/ApiExtractor/typesystemparser.cpp
index e21b97602..42a4015fc 100644
--- a/sources/shiboken6/ApiExtractor/typesystemparser.cpp
+++ b/sources/shiboken6/ApiExtractor/typesystemparser.cpp
@@ -31,6 +31,7 @@
 #include "messages.h"
 #include "reporthandler.h"
 #include "sourcelocation.h"
+#include "conditionalstreamreader.h"
 
 #include <QtCore/QDir>
 #include <QtCore/QFile>
@@ -533,13 +534,13 @@ TypeSystemParser::TypeSystemParser(TypeDatabase *database, bool generate) :
 
 TypeSystemParser::~TypeSystemParser() = default;
 
-static QString readerFileName(const QXmlStreamReader &reader)
+static QString readerFileName(const ConditionalStreamReader &reader)
 {
     const auto *file = qobject_cast<const QFile *>(reader.device());
     return file != nullptr ? file->fileName() : QString();
 }
 
-static QString msgReaderMessage(const QXmlStreamReader &reader,
+static QString msgReaderMessage(const ConditionalStreamReader &reader,
                                 const char *type,
                                 const QString &what)
 {
@@ -556,17 +557,17 @@ static QString msgReaderMessage(const QXmlStreamReader &reader,
     return message;
 }
 
-static QString msgReaderWarning(const QXmlStreamReader &reader, const QString &what)
+static QString msgReaderWarning(const ConditionalStreamReader &reader, const QString &what)
 {
     return  msgReaderMessage(reader, "Warning", what);
 }
 
-static QString msgReaderError(const QXmlStreamReader &reader, const QString &what)
+static QString msgReaderError(const ConditionalStreamReader &reader, const QString &what)
 {
     return  msgReaderMessage(reader, "Error", what);
 }
 
-static QString msgUnimplementedElementWarning(const QXmlStreamReader &reader,
+static QString msgUnimplementedElementWarning(const ConditionalStreamReader &reader,
                                               QStringView name)
 {
     QString message;
@@ -575,7 +576,7 @@ static QString msgUnimplementedElementWarning(const QXmlStreamReader &reader,
     return msgReaderMessage(reader, "Warning", message);
 }
 
-static QString msgUnimplementedAttributeWarning(const QXmlStreamReader &reader,
+static QString msgUnimplementedAttributeWarning(const ConditionalStreamReader &reader,
                                                 QStringView name)
 {
     QString message;
@@ -584,14 +585,14 @@ static QString msgUnimplementedAttributeWarning(const QXmlStreamReader &reader,
     return msgReaderMessage(reader, "Warning", message);
 }
 
-static inline QString msgUnimplementedAttributeWarning(const QXmlStreamReader &reader,
+static inline QString msgUnimplementedAttributeWarning(const ConditionalStreamReader &reader,
                                                        const QXmlStreamAttribute &attribute)
 {
     return msgUnimplementedAttributeWarning(reader, attribute.qualifiedName());
 }
 
 static QString
-    msgUnimplementedAttributeValueWarning(const QXmlStreamReader &reader,
+    msgUnimplementedAttributeValueWarning(const ConditionalStreamReader &reader,
                                           QStringView name, QStringView value)
 {
     QString message;
@@ -601,7 +602,7 @@ static QString
 }
 
 static inline
-    QString msgUnimplementedAttributeValueWarning(const QXmlStreamReader &reader,
+    QString msgUnimplementedAttributeValueWarning(const ConditionalStreamReader &reader,
                                                   const QXmlStreamAttribute &attribute)
 {
     return msgUnimplementedAttributeValueWarning(reader,
@@ -660,7 +661,7 @@ static bool addRejection(TypeDatabase *database, QXmlStreamAttributes *attribute
     return true;
 }
 
-bool TypeSystemParser::parse(QXmlStreamReader &reader)
+bool TypeSystemParser::parse(ConditionalStreamReader &reader)
 {
     m_error.clear();
     m_currentPath.clear();
@@ -671,7 +672,7 @@ bool TypeSystemParser::parse(QXmlStreamReader &reader)
     return result;
 }
 
-bool TypeSystemParser::parseXml(QXmlStreamReader &reader)
+bool TypeSystemParser::parseXml(ConditionalStreamReader &reader)
 {
     const QString fileName = readerFileName(reader);
     if (!fileName.isEmpty()) {
@@ -1153,7 +1154,7 @@ static TypeEntry *findViewedType(const QString &name)
     return nullptr;
 }
 
-bool TypeSystemParser::applyCommonAttributes(const QXmlStreamReader &reader, TypeEntry *type,
+bool TypeSystemParser::applyCommonAttributes(const ConditionalStreamReader &reader, TypeEntry *type,
                                              QXmlStreamAttributes *attributes)
 {
     type->setSourceLocation(SourceLocation(m_currentFile,
@@ -1177,7 +1178,7 @@ bool TypeSystemParser::applyCommonAttributes(const QXmlStreamReader &reader, Typ
 }
 
 FlagsTypeEntry *
-    TypeSystemParser::parseFlagsEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseFlagsEntry(const ConditionalStreamReader &reader,
                              EnumTypeEntry *enumEntry, QString flagName,
                              const QVersionNumber &since,
                              QXmlStreamAttributes *attributes)
@@ -1225,7 +1226,7 @@ FlagsTypeEntry *
 }
 
 SmartPointerTypeEntry *
-    TypeSystemParser::parseSmartPointerEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseSmartPointerEntry(const ConditionalStreamReader &reader,
                                     const QString &name, const QVersionNumber &since,
                                     QXmlStreamAttributes *attributes)
 {
@@ -1285,7 +1286,7 @@ SmartPointerTypeEntry *
 }
 
 PrimitiveTypeEntry *
-    TypeSystemParser::parsePrimitiveTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parsePrimitiveTypeEntry(const ConditionalStreamReader &reader,
                                      const QString &name, const QVersionNumber &since,
                                      QXmlStreamAttributes *attributes)
 {
@@ -1319,7 +1320,7 @@ PrimitiveTypeEntry *
 }
 
 ContainerTypeEntry *
-    TypeSystemParser::parseContainerTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseContainerTypeEntry(const ConditionalStreamReader &reader,
                                      const QString &name, const QVersionNumber &since,
                                      QXmlStreamAttributes *attributes)
 {
@@ -1344,7 +1345,7 @@ ContainerTypeEntry *
 }
 
 EnumTypeEntry *
-    TypeSystemParser::parseEnumTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseEnumTypeEntry(const ConditionalStreamReader &reader,
                                 const QString &name, const QVersionNumber &since,
                                 QXmlStreamAttributes *attributes)
 {
@@ -1385,7 +1386,7 @@ EnumTypeEntry *
 
 
 NamespaceTypeEntry *
-    TypeSystemParser::parseNamespaceTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseNamespaceTypeEntry(const ConditionalStreamReader &reader,
                                      const QString &name, const QVersionNumber &since,
                                      QXmlStreamAttributes *attributes)
 {
@@ -1446,7 +1447,7 @@ NamespaceTypeEntry *
 }
 
 ValueTypeEntry *
-    TypeSystemParser::parseValueTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseValueTypeEntry(const ConditionalStreamReader &reader,
                                  const QString &name, const QVersionNumber &since,
                                  QXmlStreamAttributes *attributes)
 {
@@ -1462,7 +1463,7 @@ ValueTypeEntry *
 }
 
 FunctionTypeEntry *
-    TypeSystemParser::parseFunctionTypeEntry(const QXmlStreamReader &reader,
+    TypeSystemParser::parseFunctionTypeEntry(const ConditionalStreamReader &reader,
                                     const QString &name, const QVersionNumber &since,
                                     QXmlStreamAttributes *attributes)
 {
@@ -1513,7 +1514,7 @@ FunctionTypeEntry *
 }
 
 TypedefEntry *
- TypeSystemParser::parseTypedefEntry(const QXmlStreamReader &reader,
+ TypeSystemParser::parseTypedefEntry(const ConditionalStreamReader &reader,
                                      const QString &name,
                                      const QVersionNumber &since,
                                      QXmlStreamAttributes *attributes)
@@ -1536,7 +1537,7 @@ TypedefEntry *
     return result;
 }
 
-void TypeSystemParser::applyComplexTypeAttributes(const QXmlStreamReader &reader,
+void TypeSystemParser::applyComplexTypeAttributes(const ConditionalStreamReader &reader,
                                          ComplexTypeEntry *ctype,
                                          QXmlStreamAttributes *attributes) const
 {
@@ -1634,7 +1635,7 @@ void TypeSystemParser::applyComplexTypeAttributes(const QXmlStreamReader &reader
         ctype->setCodeGeneration(TypeEntry::GenerationDisabled);
 }
 
-bool TypeSystemParser::parseRenameFunction(const QXmlStreamReader &,
+bool TypeSystemParser::parseRenameFunction(const ConditionalStreamReader &,
                                   QString *name, QXmlStreamAttributes *attributes)
 {
     QString signature;
@@ -1680,7 +1681,7 @@ bool TypeSystemParser::parseRenameFunction(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseInjectDocumentation(const QXmlStreamReader &,
+bool TypeSystemParser::parseInjectDocumentation(const ConditionalStreamReader &,
                                        QXmlStreamAttributes *attributes)
 {
     const int validParent = StackElement::TypeEntryMask
@@ -1723,7 +1724,7 @@ bool TypeSystemParser::parseInjectDocumentation(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseModifyDocumentation(const QXmlStreamReader &,
+bool TypeSystemParser::parseModifyDocumentation(const ConditionalStreamReader &,
                                        QXmlStreamAttributes *attributes)
 {
     const int validParent = StackElement::TypeEntryMask
@@ -1749,7 +1750,7 @@ bool TypeSystemParser::parseModifyDocumentation(const QXmlStreamReader &,
 }
 
 // m_exceptionHandling
-TypeSystemTypeEntry *TypeSystemParser::parseRootElement(const QXmlStreamReader &,
+TypeSystemTypeEntry *TypeSystemParser::parseRootElement(const ConditionalStreamReader &,
                                                const QVersionNumber &since,
                                                QXmlStreamAttributes *attributes)
 {
@@ -1810,7 +1811,7 @@ TypeSystemTypeEntry *TypeSystemParser::parseRootElement(const QXmlStreamReader &
     return moduleEntry;
 }
 
-bool TypeSystemParser::loadTypesystem(const QXmlStreamReader &,
+bool TypeSystemParser::loadTypesystem(const ConditionalStreamReader &,
                              QXmlStreamAttributes *attributes)
 {
     QString typeSystemName;
@@ -1834,7 +1835,7 @@ bool TypeSystemParser::loadTypesystem(const QXmlStreamReader &,
     return result;
 }
 
-bool TypeSystemParser::parseRejectEnumValue(const QXmlStreamReader &,
+bool TypeSystemParser::parseRejectEnumValue(const ConditionalStreamReader &,
                                    QXmlStreamAttributes *attributes)
 {
     if (!m_currentEnum) {
@@ -1850,7 +1851,7 @@ bool TypeSystemParser::parseRejectEnumValue(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseReplaceArgumentType(const QXmlStreamReader &,
+bool TypeSystemParser::parseReplaceArgumentType(const ConditionalStreamReader &,
                                        const StackElement &topElement,
                                        QXmlStreamAttributes *attributes)
 {
@@ -1868,7 +1869,7 @@ bool TypeSystemParser::parseReplaceArgumentType(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseCustomConversion(const QXmlStreamReader &,
+bool TypeSystemParser::parseCustomConversion(const ConditionalStreamReader &,
                                     const StackElement &topElement,
                                     QXmlStreamAttributes *attributes)
 {
@@ -1943,7 +1944,7 @@ bool TypeSystemParser::parseCustomConversion(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseNativeToTarget(const QXmlStreamReader &,
+bool TypeSystemParser::parseNativeToTarget(const ConditionalStreamReader &,
                                   const StackElement &topElement,
                                   QXmlStreamAttributes *attributes)
 {
@@ -1958,7 +1959,7 @@ bool TypeSystemParser::parseNativeToTarget(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseAddConversion(const QXmlStreamReader &,
+bool TypeSystemParser::parseAddConversion(const ConditionalStreamReader &,
                                  const StackElement &topElement,
                                  QXmlStreamAttributes *attributes)
 {
@@ -2009,7 +2010,7 @@ static bool parseArgumentIndex(const QString &index, int *result, QString *error
     return parseIndex(index, result, errorMessage);
 }
 
-bool TypeSystemParser::parseModifyArgument(const QXmlStreamReader &,
+bool TypeSystemParser::parseModifyArgument(const ConditionalStreamReader &,
                                   const StackElement &topElement, QXmlStreamAttributes *attributes)
 {
     if (topElement.type != StackElement::ModifyFunction
@@ -2051,7 +2052,7 @@ bool TypeSystemParser::parseModifyArgument(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseNoNullPointer(const QXmlStreamReader &reader,
+bool TypeSystemParser::parseNoNullPointer(const ConditionalStreamReader &reader,
                                  const StackElement &topElement, QXmlStreamAttributes *attributes)
 {
     if (topElement.type != StackElement::ModifyArgument) {
@@ -2072,7 +2073,7 @@ bool TypeSystemParser::parseNoNullPointer(const QXmlStreamReader &reader,
     return true;
 }
 
-bool TypeSystemParser::parseDefineOwnership(const QXmlStreamReader &,
+bool TypeSystemParser::parseDefineOwnership(const ConditionalStreamReader &,
                                    const StackElement &topElement,
                                    QXmlStreamAttributes *attributes)
 {
@@ -2122,7 +2123,7 @@ bool TypeSystemParser::parseDefineOwnership(const QXmlStreamReader &,
 }
 
 // ### fixme PySide7: remove (replaced by attribute).
-bool TypeSystemParser::parseRename(const QXmlStreamReader &,
+bool TypeSystemParser::parseRename(const ConditionalStreamReader &,
                           const StackElement &topElement,
                           QXmlStreamAttributes *attributes)
 {
@@ -2141,7 +2142,7 @@ bool TypeSystemParser::parseRename(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseModifyField(const QXmlStreamReader &,
+bool TypeSystemParser::parseModifyField(const ConditionalStreamReader &,
                                         QXmlStreamAttributes *attributes)
 {
     FieldModification fm;
@@ -2188,7 +2189,7 @@ static bool parseOverloadNumber(const QXmlStreamAttribute &attribute, int *overl
     return true;
 }
 
-bool TypeSystemParser::parseAddFunction(const QXmlStreamReader &,
+bool TypeSystemParser::parseAddFunction(const ConditionalStreamReader &,
                                         const StackElement &topElement,
                                         StackElement::ElementType t,
                                         QXmlStreamAttributes *attributes)
@@ -2267,7 +2268,7 @@ bool TypeSystemParser::parseAddFunction(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseProperty(const QXmlStreamReader &, const StackElement &topElement,
+bool TypeSystemParser::parseProperty(const ConditionalStreamReader &, const StackElement &topElement,
                                      QXmlStreamAttributes *attributes)
 {
     if ((topElement.type & StackElement::ComplexTypeEntryMask) == 0) {
@@ -2301,7 +2302,7 @@ bool TypeSystemParser::parseProperty(const QXmlStreamReader &, const StackElemen
     return true;
 }
 
-bool TypeSystemParser::parseModifyFunction(const QXmlStreamReader &reader,
+bool TypeSystemParser::parseModifyFunction(const ConditionalStreamReader &reader,
                                   const StackElement &topElement,
                                   QXmlStreamAttributes *attributes)
 {
@@ -2432,7 +2433,7 @@ bool TypeSystemParser::parseModifyFunction(const QXmlStreamReader &reader,
     return true;
 }
 
-bool TypeSystemParser::parseReplaceDefaultExpression(const QXmlStreamReader &,
+bool TypeSystemParser::parseReplaceDefaultExpression(const ConditionalStreamReader &,
                                             const StackElement &topElement,
                                             QXmlStreamAttributes *attributes)
 {
@@ -2452,7 +2453,7 @@ bool TypeSystemParser::parseReplaceDefaultExpression(const QXmlStreamReader &,
 }
 
 CustomFunction *
-    TypeSystemParser::parseCustomMetaConstructor(const QXmlStreamReader &,
+    TypeSystemParser::parseCustomMetaConstructor(const ConditionalStreamReader &,
                                         StackElement::ElementType type,
                                         const StackElement &topElement,
                                         QXmlStreamAttributes *attributes)
@@ -2473,7 +2474,7 @@ CustomFunction *
     return func;
 }
 
-bool TypeSystemParser::parseReferenceCount(const QXmlStreamReader &reader,
+bool TypeSystemParser::parseReferenceCount(const ConditionalStreamReader &reader,
                                   const StackElement &topElement,
                                   QXmlStreamAttributes *attributes)
 {
@@ -2511,7 +2512,7 @@ bool TypeSystemParser::parseReferenceCount(const QXmlStreamReader &reader,
     return true;
 }
 
-bool TypeSystemParser::parseParentOwner(const QXmlStreamReader &,
+bool TypeSystemParser::parseParentOwner(const ConditionalStreamReader &,
                                const StackElement &topElement,
                                QXmlStreamAttributes *attributes)
 {
@@ -2586,7 +2587,7 @@ bool TypeSystemParser::readFileSnippet(QXmlStreamAttributes *attributes, CodeSni
     return true;
 }
 
-bool TypeSystemParser::parseInjectCode(const QXmlStreamReader &,
+bool TypeSystemParser::parseInjectCode(const ConditionalStreamReader &,
                               const StackElement &topElement,
                               StackElement* element, QXmlStreamAttributes *attributes)
 {
@@ -2642,7 +2643,7 @@ bool TypeSystemParser::parseInjectCode(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseInclude(const QXmlStreamReader &,
+bool TypeSystemParser::parseInclude(const ConditionalStreamReader &,
                            const StackElement &topElement,
                            TypeEntry *entry, QXmlStreamAttributes *attributes)
 {
@@ -2676,7 +2677,7 @@ bool TypeSystemParser::parseInclude(const QXmlStreamReader &,
     return true;
 }
 
-bool TypeSystemParser::parseSystemInclude(const QXmlStreamReader &,
+bool TypeSystemParser::parseSystemInclude(const ConditionalStreamReader &,
                                           QXmlStreamAttributes *attributes)
 {
     const int index = indexOfAttribute(*attributes, fileNameAttribute());
@@ -2689,7 +2690,7 @@ bool TypeSystemParser::parseSystemInclude(const QXmlStreamReader &,
 }
 
 TemplateInstance *
-    TypeSystemParser::parseTemplateInstanceEnum(const QXmlStreamReader &,
+    TypeSystemParser::parseTemplateInstanceEnum(const ConditionalStreamReader &,
                                        const StackElement &topElement,
                                        QXmlStreamAttributes *attributes)
 {
@@ -2712,7 +2713,7 @@ TemplateInstance *
     return new TemplateInstance(attributes->takeAt(nameIndex).value().toString());
 }
 
-bool TypeSystemParser::parseReplace(const QXmlStreamReader &,
+bool TypeSystemParser::parseReplace(const ConditionalStreamReader &,
                            const StackElement &topElement,
                            StackElement *element, QXmlStreamAttributes *attributes)
 {
@@ -2744,7 +2745,7 @@ static bool parseVersion(const QString &versionSpec, const QString &package,
     return true;
 }
 
-bool TypeSystemParser::startElement(const QXmlStreamReader &reader)
+bool TypeSystemParser::startElement(const ConditionalStreamReader &reader)
 {
     if (m_ignoreDepth) {
         ++m_ignoreDepth;
diff --git a/sources/shiboken6/ApiExtractor/typesystemparser.h b/sources/shiboken6/ApiExtractor/typesystemparser.h
index efb7e2d8f..585210dca 100644
--- a/sources/shiboken6/ApiExtractor/typesystemparser.h
+++ b/sources/shiboken6/ApiExtractor/typesystemparser.h
@@ -39,6 +39,8 @@ QT_FORWARD_DECLARE_CLASS(QVersionNumber)
 QT_FORWARD_DECLARE_CLASS(QXmlStreamAttributes)
 QT_FORWARD_DECLARE_CLASS(QXmlStreamReader)
 
+class ConditionalStreamReader;
+
 class TypeSystemEntityResolver;
 class TypeDatabase;
 class StackElement
@@ -149,15 +151,15 @@ public:
     TypeSystemParser(TypeDatabase* database, bool generate);
     ~TypeSystemParser();
 
-    bool parse(QXmlStreamReader &reader);
+    bool parse(ConditionalStreamReader &reader);
 
     QString errorString() const { return m_error; }
 
 private:
-    bool parseXml(QXmlStreamReader &reader);
+    bool parseXml(ConditionalStreamReader &reader);
     bool setupSmartPointerInstantiations();
-    bool startElement(const QXmlStreamReader &reader);
-    SmartPointerTypeEntry *parseSmartPointerEntry(const QXmlStreamReader &,
+    bool startElement(const ConditionalStreamReader &reader);
+    SmartPointerTypeEntry *parseSmartPointerEntry(const ConditionalStreamReader &,
                                                   const QString &name,
                                                   const QVersionNumber &since,
                                                   QXmlStreamAttributes *attributes);
@@ -169,90 +171,90 @@ private:
 
     const TypeEntry *currentParentTypeEntry() const;
     bool checkRootElement();
-    bool applyCommonAttributes(const QXmlStreamReader &reader, TypeEntry *type,
+    bool applyCommonAttributes(const ConditionalStreamReader &reader, TypeEntry *type,
                                QXmlStreamAttributes *attributes);
     PrimitiveTypeEntry *
-        parsePrimitiveTypeEntry(const QXmlStreamReader &, const QString &name,
+        parsePrimitiveTypeEntry(const ConditionalStreamReader &, const QString &name,
                                 const QVersionNumber &since, QXmlStreamAttributes *);
     ContainerTypeEntry *
-        parseContainerTypeEntry(const QXmlStreamReader &, const QString &name,
+        parseContainerTypeEntry(const ConditionalStreamReader &, const QString &name,
                                  const QVersionNumber &since, QXmlStreamAttributes *);
     EnumTypeEntry *
-        parseEnumTypeEntry(const QXmlStreamReader &, const QString &name,
+        parseEnumTypeEntry(const ConditionalStreamReader &, const QString &name,
                            const QVersionNumber &since, QXmlStreamAttributes *);
     FlagsTypeEntry *
-        parseFlagsEntry(const QXmlStreamReader &, EnumTypeEntry *enumEntry,
+        parseFlagsEntry(const ConditionalStreamReader &, EnumTypeEntry *enumEntry,
                         QString flagName, const QVersionNumber &since,
                         QXmlStreamAttributes *);
 
     NamespaceTypeEntry *
-        parseNamespaceTypeEntry(const QXmlStreamReader &,
+        parseNamespaceTypeEntry(const ConditionalStreamReader &,
                                 const QString &name, const QVersionNumber &since,
                                 QXmlStreamAttributes *attributes);
 
     ValueTypeEntry *
-        parseValueTypeEntry(const QXmlStreamReader &, const QString &name,
+        parseValueTypeEntry(const ConditionalStreamReader &, const QString &name,
                             const QVersionNumber &since, QXmlStreamAttributes *);
     FunctionTypeEntry *
-        parseFunctionTypeEntry(const QXmlStreamReader &, const QString &name,
+        parseFunctionTypeEntry(const ConditionalStreamReader &, const QString &name,
                                const QVersionNumber &since, QXmlStreamAttributes *);
     TypedefEntry *
-        parseTypedefEntry(const QXmlStreamReader &, const QString &name,
+        parseTypedefEntry(const ConditionalStreamReader &, const QString &name,
                           const QVersionNumber &since, QXmlStreamAttributes *);
-    void applyComplexTypeAttributes(const QXmlStreamReader &, ComplexTypeEntry *ctype,
+    void applyComplexTypeAttributes(const ConditionalStreamReader &, ComplexTypeEntry *ctype,
                                     QXmlStreamAttributes *) const;
-    bool parseRenameFunction(const QXmlStreamReader &, QString *name,
+    bool parseRenameFunction(const ConditionalStreamReader &, QString *name,
                              QXmlStreamAttributes *);
-    bool parseInjectDocumentation(const QXmlStreamReader &, QXmlStreamAttributes *);
-    bool parseModifyDocumentation(const QXmlStreamReader &, QXmlStreamAttributes *);
+    bool parseInjectDocumentation(const ConditionalStreamReader &, QXmlStreamAttributes *);
+    bool parseModifyDocumentation(const ConditionalStreamReader &, QXmlStreamAttributes *);
     TypeSystemTypeEntry *
-        parseRootElement(const QXmlStreamReader &, const QVersionNumber &since,
+        parseRootElement(const ConditionalStreamReader &, const QVersionNumber &since,
                          QXmlStreamAttributes *);
-    bool loadTypesystem(const QXmlStreamReader &, QXmlStreamAttributes *);
-    bool parseRejectEnumValue(const QXmlStreamReader &, QXmlStreamAttributes *);
-    bool parseReplaceArgumentType(const QXmlStreamReader &, const StackElement &topElement,
+    bool loadTypesystem(const ConditionalStreamReader &, QXmlStreamAttributes *);
+    bool parseRejectEnumValue(const ConditionalStreamReader &, QXmlStreamAttributes *);
+    bool parseReplaceArgumentType(const ConditionalStreamReader &, const StackElement &topElement,
                                   QXmlStreamAttributes *);
-    bool parseCustomConversion(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseCustomConversion(const ConditionalStreamReader &, const StackElement &topElement,
                                QXmlStreamAttributes *);
-    bool parseAddConversion(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseAddConversion(const ConditionalStreamReader &, const StackElement &topElement,
                             QXmlStreamAttributes *);
-    bool parseNativeToTarget(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseNativeToTarget(const ConditionalStreamReader &, const StackElement &topElement,
                              QXmlStreamAttributes *attributes);
-    bool parseModifyArgument(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseModifyArgument(const ConditionalStreamReader &, const StackElement &topElement,
                              QXmlStreamAttributes *attributes);
-    bool parseNoNullPointer(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseNoNullPointer(const ConditionalStreamReader &, const StackElement &topElement,
                             QXmlStreamAttributes *attributes);
-    bool parseDefineOwnership(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseDefineOwnership(const ConditionalStreamReader &, const StackElement &topElement,
                               QXmlStreamAttributes *);
-    bool parseRename(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseRename(const ConditionalStreamReader &, const StackElement &topElement,
                      QXmlStreamAttributes *);
-    bool parseModifyField(const QXmlStreamReader &, QXmlStreamAttributes *);
-    bool parseAddFunction(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseModifyField(const ConditionalStreamReader &, QXmlStreamAttributes *);
+    bool parseAddFunction(const ConditionalStreamReader &, const StackElement &topElement,
                           StackElement::ElementType t, QXmlStreamAttributes *);
-    bool parseProperty(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseProperty(const ConditionalStreamReader &, const StackElement &topElement,
                        QXmlStreamAttributes *);
-    bool parseModifyFunction(const QXmlStreamReader &, const StackElement &topElement,
+    bool parseModifyFunction(const ConditionalStreamReader &, const StackElement &topElement,
                              QXmlStreamAttributes *);
-    bool parseReplaceDefaultExpression(const QXmlStreamReader &,
+    bool parseReplaceDefaultExpression(const ConditionalStreamReader &,
                                        const StackElement &topElement, QXmlStreamAttributes *);
     static CustomFunction *
-        parseCustomMetaConstructor(const QXmlStreamReader &,
+        parseCustomMetaConstructor(const ConditionalStreamReader &,
                                    StackElement::ElementType type,
                                    const StackElement &topElement, QXmlStreamAttributes *);
-     bool parseReferenceCount(const QXmlStreamReader &, const StackElement &topElement,
+     bool parseReferenceCount(const ConditionalStreamReader &, const StackElement &topElement,
                               QXmlStreamAttributes *);
-     bool parseParentOwner(const QXmlStreamReader &, const StackElement &topElement,
+     bool parseParentOwner(const ConditionalStreamReader &, const StackElement &topElement,
                            QXmlStreamAttributes *);
      bool readFileSnippet(QXmlStreamAttributes *attributes, CodeSnip *snip);
-     bool parseInjectCode(const QXmlStreamReader &, const StackElement &topElement,
+     bool parseInjectCode(const ConditionalStreamReader &, const StackElement &topElement,
                           StackElement* element, QXmlStreamAttributes *);
-     bool parseInclude(const QXmlStreamReader &, const StackElement &topElement,
+     bool parseInclude(const ConditionalStreamReader &, const StackElement &topElement,
                        TypeEntry *entry, QXmlStreamAttributes *);
-     bool parseSystemInclude(const QXmlStreamReader &, QXmlStreamAttributes *);
+     bool parseSystemInclude(const ConditionalStreamReader &, QXmlStreamAttributes *);
      TemplateInstance
-         *parseTemplateInstanceEnum(const QXmlStreamReader &, const StackElement &topElement,
+         *parseTemplateInstanceEnum(const ConditionalStreamReader &, const StackElement &topElement,
                                     QXmlStreamAttributes *);
-     bool parseReplace(const QXmlStreamReader &, const StackElement &topElement,
+     bool parseReplace(const ConditionalStreamReader &, const StackElement &topElement,
                        StackElement *element, QXmlStreamAttributes *);
 
     TypeDatabase* m_database;
diff --git a/sources/shiboken6/doc/shibokengenerator.rst b/sources/shiboken6/doc/shibokengenerator.rst
index d811ee25f..bf7e06f0b 100644
--- a/sources/shiboken6/doc/shibokengenerator.rst
+++ b/sources/shiboken6/doc/shibokengenerator.rst
@@ -136,6 +136,12 @@ Options
     fully qualified Python type names ('Module.Class'), but the module can
     be omitted ('Class').
 
+.. _conditional_keywords:
+
+``-keywords=keyword1[,keyword2,...]``
+    A comma-separated list of keywords for conditional typesystem parsing
+    (see :ref:`conditional_processing`).
+
 ``--use-global-header``
     Use the global headers passed on the command line in generated code.
 
diff --git a/sources/shiboken6/doc/typesystem_specifying_types.rst b/sources/shiboken6/doc/typesystem_specifying_types.rst
index 1172b3f15..fadc78cd2 100644
--- a/sources/shiboken6/doc/typesystem_specifying_types.rst
+++ b/sources/shiboken6/doc/typesystem_specifying_types.rst
@@ -577,3 +577,27 @@ system-include
             <system-include file-name="memory"/>
             <system-include file-name="/usr/include/Qt/"/>
         </typesystem>
+
+.. _conditional_processing:
+
+Conditional Processing
+^^^^^^^^^^^^^^^^^^^^^^
+
+     Simple processing instructions are provided for including or excluding
+     sections depending on the presence of keywords. The syntax is:
+
+     .. code-block:: xml
+
+         <?if keyword !excluded_keyword ?>
+            ...
+         <?endif?>
+
+     There are predefined keywords indicating the operating system (``windows``,
+     ``unix`` and ``darwin``). The class names passed to the
+     :ref:`--drop-type-entries <drop-type-entries>` command line option
+     are also predefined, prefixed by ``no_``. This allows for example
+     for enclosing added functions referring to those classes within
+     ``<?if !no_ClassName?>``, ``<?endif?>``.
+
+     Other keywords can be specified using the
+     :ref:`--keywords <conditional_keywords>` command line option.
diff --git a/sources/shiboken6/generator/main.cpp b/sources/shiboken6/generator/main.cpp
index dbb25d796..315e963c4 100644
--- a/sources/shiboken6/generator/main.cpp
+++ b/sources/shiboken6/generator/main.cpp
@@ -47,9 +47,11 @@
 #include <exception>
 
 static const QChar clangOptionsSplitter = u',';
+static const QChar keywordsSplitter = u',';
 static const QChar dropTypeEntriesSplitter = u';';
 static const QChar apiVersionSplitter = u'|';
 
+static inline QString keywordsOption() { return QStringLiteral("keywords"); }
 static inline QString clangOptionOption() { return QStringLiteral("clang-option"); }
 static inline QString clangOptionsOption() { return QStringLiteral("clang-options"); }
 static inline QString apiVersionOption() { return QStringLiteral("api-version"); }
@@ -191,6 +193,9 @@ static std::optional<CommandLineArguments>
         } else if (key == "api-version") {
             args.addToOptionsList(apiVersionOption(),
                                   value, apiVersionSplitter);
+        } else if (key == "keywords") {
+            args.addToOptionsList(keywordsOption(),
+                                  value, keywordsSplitter);
         } else if (key == "drop-type-entries") {
             args.addToOptionsList(dropTypeEntriesOption(),
                                   value, dropTypeEntriesSplitter);
@@ -263,6 +268,8 @@ static void getCommandLineArg(QString arg, int &argNum, CommandLineArguments &ar
             args.addToOptionsList(clangOptionsOption(), value);
         } else if (option == clangOptionsOption()) {
             args.addToOptionsList(clangOptionsOption(), value, clangOptionsSplitter);
+        } else if (option == keywordsOption()) {
+            args.addToOptionsList(keywordsOption(), value, keywordsSplitter);
         } else {
             args.options.insert(option, value);
         }
@@ -344,6 +351,8 @@ void printUsage()
         {QLatin1String("drop-type-entries=\"<TypeEntry0>[;TypeEntry1;...]\""),
          QLatin1String("Semicolon separated list of type system entries (classes, namespaces,\n"
                        "global functions and enums) to be dropped from generation.")},
+        {keywordsOption() + QStringLiteral("=keyword1[,keyword2,...]"),
+         QLatin1String("A comma-separated list of keywords for conditional typesystem parsing")},
         {clangOptionOption(),
          QLatin1String("Option to be passed to clang")},
         {clangOptionsOption(),
@@ -584,6 +593,12 @@ int shibokenMain(int argc, char *argv[])
         args.options.erase(ait);
     }
 
+    ait = args.options.find(keywordsOption());
+    if (ait != args.options.end()) {
+        extractor.setTypesystemKeywords(ait.value().toStringList());
+        args.options.erase(ait);
+    }
+
     ait = args.options.find(typesystemPathOption());
     if (ait != args.options.end()) {
         extractor.addTypesystemSearchPath(ait.value().toStringList());