Serialization converter example: const-ify the Converter type

Its methods act on their parameters without changing the converter, so
can all be const. Its instances thus have no non-const members to
exercise, so can always be const.

Pick-to: 6.6 6.5
Task-number: QTBUG-111228
Change-Id: Ifcdb2f2159c2cfcd7998dd118aa327a32d299ccf
Reviewed-by: Dennis Oberst <dennis.oberst@qt.io>
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

16 files changed, 143 insertions, 129 deletions

diff --git a/examples/corelib/serialization/convert/cborconverter.cpp b/examples/corelib/serialization/convert/cborconverter.cpp
index c54c84fc2e..992f17e06c 100644
--- a/examples/corelib/serialization/convert/cborconverter.cpp
+++ b/examples/corelib/serialization/convert/cborconverter.cpp
@@ -120,33 +120,33 @@ static QCborValue convertFromVariant(const QVariant &v, TrimFloatingPoint fpTrim
 }
 //! [1]
 
-QString CborDiagnosticDumper::name()
+QString CborDiagnosticDumper::name() const
 {
     return "cbor-dump"_L1;
 }
 
-Converter::Direction CborDiagnosticDumper::directions()
+Converter::Direction CborDiagnosticDumper::directions() const
 {
     return Out;
 }
 
-Converter::Options CborDiagnosticDumper::outputOptions()
+Converter::Options CborDiagnosticDumper::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *CborDiagnosticDumper::optionsHelp()
+const char *CborDiagnosticDumper::optionsHelp() const
 {
     return diagnosticHelp;
 }
 
-bool CborDiagnosticDumper::probeFile(QIODevice *f)
+bool CborDiagnosticDumper::probeFile(QIODevice *f) const
 {
     Q_UNUSED(f);
     return false;
 }
 
-QVariant CborDiagnosticDumper::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant CborDiagnosticDumper::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     Q_UNREACHABLE();
     Q_UNUSED(f);
@@ -155,7 +155,7 @@ QVariant CborDiagnosticDumper::loadFile(QIODevice *f, Converter *&outputConverte
 }
 
 void CborDiagnosticDumper::saveFile(QIODevice *f, const QVariant &contents,
-                                    const QStringList &options)
+                                    const QStringList &options) const
 {
     QCborValue::DiagnosticNotationOptions opts = QCborValue::LineWrapped;
     for (const QString &s : options) {
@@ -192,27 +192,27 @@ CborConverter::CborConverter()
     qRegisterMetaType<QCborTag>();
 }
 
-QString CborConverter::name()
+QString CborConverter::name() const
 {
     return "cbor";
 }
 
-Converter::Direction CborConverter::directions()
+Converter::Direction CborConverter::directions() const
 {
     return InOut;
 }
 
-Converter::Options CborConverter::outputOptions()
+Converter::Options CborConverter::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *CborConverter::optionsHelp()
+const char *CborConverter::optionsHelp() const
 {
     return cborOptionHelp;
 }
 
-bool CborConverter::probeFile(QIODevice *f)
+bool CborConverter::probeFile(QIODevice *f) const
 {
     if (QFile *file = qobject_cast<QFile *>(f)) {
         if (file->fileName().endsWith(".cbor"_L1))
@@ -222,7 +222,7 @@ bool CborConverter::probeFile(QIODevice *f)
 }
 
 //! [2]
-QVariant CborConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant CborConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     const char *ptr = nullptr;
     if (auto file = qobject_cast<QFile *>(f))
@@ -258,7 +258,7 @@ QVariant CborConverter::loadFile(QIODevice *f, Converter *&outputConverter)
 }
 //! [2]
 //! [3]
-void CborConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void CborConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) const
 {
     //! [3]
     bool useSignature = true;
diff --git a/examples/corelib/serialization/convert/cborconverter.h b/examples/corelib/serialization/convert/cborconverter.h
index d19c9eb33e..18bd55e09c 100644
--- a/examples/corelib/serialization/convert/cborconverter.h
+++ b/examples/corelib/serialization/convert/cborconverter.h
@@ -10,13 +10,14 @@ class CborDiagnosticDumper : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 class CborConverter : public Converter
@@ -26,13 +27,14 @@ public:
 
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // CBORCONVERTER_H
diff --git a/examples/corelib/serialization/convert/converter.h b/examples/corelib/serialization/convert/converter.h
index 0510f050ec..786893bd4a 100644
--- a/examples/corelib/serialization/convert/converter.h
+++ b/examples/corelib/serialization/convert/converter.h
@@ -39,13 +39,14 @@ public:
 
     virtual ~Converter() = 0;
 
-    virtual QString name() = 0;
-    virtual Direction directions() = 0;
-    virtual Options outputOptions() = 0;
-    virtual const char *optionsHelp() = 0;
-    virtual bool probeFile(QIODevice *f) = 0;
-    virtual QVariant loadFile(QIODevice *f, Converter *&outputConverter) = 0;
-    virtual void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) = 0;
+    virtual QString name() const = 0;
+    virtual Direction directions() const = 0;
+    virtual Options outputOptions() const = 0;
+    virtual const char *optionsHelp() const = 0;
+    virtual bool probeFile(QIODevice *f) const = 0;
+    virtual QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const = 0;
+    virtual void saveFile(QIODevice *f, const QVariant &contents,
+                          const QStringList &options) const = 0;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(Converter::Options)
diff --git a/examples/corelib/serialization/convert/datastreamconverter.cpp b/examples/corelib/serialization/convert/datastreamconverter.cpp
index af02cf3259..f994f1583c 100644
--- a/examples/corelib/serialization/convert/datastreamconverter.cpp
+++ b/examples/corelib/serialization/convert/datastreamconverter.cpp
@@ -48,32 +48,32 @@ DataStreamConverter::DataStreamConverter()
     qRegisterMetaType<VariantOrderedMap>();
 }
 
-QString DataStreamConverter::name()
+QString DataStreamConverter::name() const
 {
     return "datastream"_L1;
 }
 
-Converter::Direction DataStreamConverter::directions()
+Converter::Direction DataStreamConverter::directions() const
 {
     return InOut;
 }
 
-Converter::Options DataStreamConverter::outputOptions()
+Converter::Options DataStreamConverter::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *DataStreamConverter::optionsHelp()
+const char *DataStreamConverter::optionsHelp() const
 {
     return dataStreamOptionHelp;
 }
 
-bool DataStreamConverter::probeFile(QIODevice *f)
+bool DataStreamConverter::probeFile(QIODevice *f) const
 {
     return f->isReadable() && f->peek(sizeof(signature) - 1) == signature;
 }
 
-QVariant DataStreamConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant DataStreamConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     if (!outputConverter)
         outputConverter = &debugTextDumper;
@@ -97,7 +97,7 @@ QVariant DataStreamConverter::loadFile(QIODevice *f, Converter *&outputConverter
 }
 
 void DataStreamConverter::saveFile(QIODevice *f, const QVariant &contents,
-                                   const QStringList &options)
+                                   const QStringList &options) const
 {
     QDataStream::Version version = QDataStream::Qt_6_0;
     auto order = QDataStream::ByteOrder(QSysInfo::ByteOrder);
diff --git a/examples/corelib/serialization/convert/datastreamconverter.h b/examples/corelib/serialization/convert/datastreamconverter.h
index c2a783708e..a6d99c0f8e 100644
--- a/examples/corelib/serialization/convert/datastreamconverter.h
+++ b/examples/corelib/serialization/convert/datastreamconverter.h
@@ -13,13 +13,14 @@ public:
 
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // DATASTREAMCONVERTER_H
diff --git a/examples/corelib/serialization/convert/debugtextdumper.cpp b/examples/corelib/serialization/convert/debugtextdumper.cpp
index ef3d2ee2f8..fcaa877c36 100644
--- a/examples/corelib/serialization/convert/debugtextdumper.cpp
+++ b/examples/corelib/serialization/convert/debugtextdumper.cpp
@@ -43,33 +43,33 @@ static QString dumpVariant(const QVariant &v, const QString &indent = "\n"_L1)
     return result;
 }
 
-QString DebugTextDumper::name()
+QString DebugTextDumper::name() const
 {
     return "debugtext-dump"_L1;
 }
 
-Converter::Direction DebugTextDumper::directions()
+Converter::Direction DebugTextDumper::directions() const
 {
     return Out;
 }
 
-Converter::Options DebugTextDumper::outputOptions()
+Converter::Options DebugTextDumper::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *DebugTextDumper::optionsHelp()
+const char *DebugTextDumper::optionsHelp() const
 {
     return nullptr;
 }
 
-bool DebugTextDumper::probeFile(QIODevice *f)
+bool DebugTextDumper::probeFile(QIODevice *f) const
 {
     Q_UNUSED(f);
     return false;
 }
 
-QVariant DebugTextDumper::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant DebugTextDumper::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     Q_UNREACHABLE();
     Q_UNUSED(f);
@@ -77,7 +77,8 @@ QVariant DebugTextDumper::loadFile(QIODevice *f, Converter *&outputConverter)
     return QVariant();
 }
 
-void DebugTextDumper::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void DebugTextDumper::saveFile(QIODevice *f, const QVariant &contents,
+                               const QStringList &options) const
 {
     Q_UNUSED(options);
     QString s = dumpVariant(contents);
diff --git a/examples/corelib/serialization/convert/debugtextdumper.h b/examples/corelib/serialization/convert/debugtextdumper.h
index 4395bd4822..d39a0eb427 100644
--- a/examples/corelib/serialization/convert/debugtextdumper.h
+++ b/examples/corelib/serialization/convert/debugtextdumper.h
@@ -10,13 +10,14 @@ class DebugTextDumper : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // DEBUGTEXTDUMPER_H
diff --git a/examples/corelib/serialization/convert/jsonconverter.cpp b/examples/corelib/serialization/convert/jsonconverter.cpp
index 30cad162b5..23d8cb98c3 100644
--- a/examples/corelib/serialization/convert/jsonconverter.cpp
+++ b/examples/corelib/serialization/convert/jsonconverter.cpp
@@ -25,27 +25,27 @@ static QJsonDocument convertFromVariant(const QVariant &v)
     return doc;
 }
 
-QString JsonConverter::name()
+QString JsonConverter::name() const
 {
     return "json"_L1;
 }
 
-Converter::Direction JsonConverter::directions()
+Converter::Direction JsonConverter::directions() const
 {
     return InOut;
 }
 
-Converter::Options JsonConverter::outputOptions()
+Converter::Options JsonConverter::outputOptions() const
 {
     return {};
 }
 
-const char *JsonConverter::optionsHelp()
+const char *JsonConverter::optionsHelp() const
 {
     return jsonOptionHelp;
 }
 
-bool JsonConverter::probeFile(QIODevice *f)
+bool JsonConverter::probeFile(QIODevice *f) const
 {
     if (QFile *file = qobject_cast<QFile *>(f)) {
         if (file->fileName().endsWith(".json"_L1))
@@ -59,7 +59,7 @@ bool JsonConverter::probeFile(QIODevice *f)
     return false;
 }
 
-QVariant JsonConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant JsonConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     if (!outputConverter)
         outputConverter = this;
@@ -84,7 +84,8 @@ QVariant JsonConverter::loadFile(QIODevice *f, Converter *&outputConverter)
     return doc.toVariant();
 }
 
-void JsonConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void JsonConverter::saveFile(QIODevice *f, const QVariant &contents,
+                             const QStringList &options) const
 {
     QJsonDocument::JsonFormat format = QJsonDocument::Indented;
     for (const QString &s : options) {
diff --git a/examples/corelib/serialization/convert/jsonconverter.h b/examples/corelib/serialization/convert/jsonconverter.h
index 2aa6c55543..07011c9395 100644
--- a/examples/corelib/serialization/convert/jsonconverter.h
+++ b/examples/corelib/serialization/convert/jsonconverter.h
@@ -10,13 +10,14 @@ class JsonConverter : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // JSONCONVERTER_H
diff --git a/examples/corelib/serialization/convert/main.cpp b/examples/corelib/serialization/convert/main.cpp
index 20ae228fbf..697236dd7d 100644
--- a/examples/corelib/serialization/convert/main.cpp
+++ b/examples/corelib/serialization/convert/main.cpp
@@ -13,12 +13,12 @@
 
 using namespace Qt::StringLiterals;
 
-static QList<Converter *> *availableConverters;
+static QList<const Converter *> *availableConverters;
 
 Converter::Converter()
 {
     if (!availableConverters)
-        availableConverters = new QList<Converter *>;
+        availableConverters = new QList<const Converter *>;
     availableConverters->append(this);
 }
 
@@ -33,7 +33,7 @@ int main(int argc, char *argv[])
 
     QStringList inputFormats;
     QStringList outputFormats;
-    for (Converter *conv : std::as_const(*availableConverters)) {
+    for (const Converter *conv : std::as_const(*availableConverters)) {
         auto direction = conv->directions();
         QString name = conv->name();
         if (direction & Converter::In)
@@ -86,7 +86,7 @@ int main(int argc, char *argv[])
 
     if (parser.isSet(formatOptionsOption)) {
         QString format = parser.value(formatOptionsOption);
-        for (Converter *conv : std::as_const(*availableConverters)) {
+        for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->name() == format) {
                 const char *help = conv->optionsHelp();
                 if (help) {
@@ -103,10 +103,10 @@ int main(int argc, char *argv[])
         return EXIT_FAILURE;
     }
 
-    Converter *inconv = nullptr;
+    const Converter *inconv = nullptr;
     QString format = parser.value(inputFormatOption);
     if (format != "auto"_L1) {
-        for (Converter *conv : std::as_const(*availableConverters)) {
+        for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->name() == format) {
                 inconv = conv;
                 break;
@@ -119,10 +119,10 @@ int main(int argc, char *argv[])
         }
     }
 
-    Converter *outconv = nullptr;
+    const Converter *outconv = nullptr;
     format = parser.value(outputFormatOption);
     if (format != "auto"_L1) {
-        for (Converter *conv : std::as_const(*availableConverters)) {
+        for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->name() == format) {
                 outconv = conv;
                 break;
@@ -161,7 +161,7 @@ int main(int argc, char *argv[])
 
     if (!inconv) {
         // probe the input to find a file format
-        for (Converter *conv : std::as_const(*availableConverters)) {
+        for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->directions() & Converter::In && conv->probeFile(&input)) {
                 inconv = conv;
                 break;
@@ -176,7 +176,7 @@ int main(int argc, char *argv[])
 
     if (!outconv) {
         // probe the output to find a file format
-        for (Converter *conv : std::as_const(*availableConverters)) {
+        for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->directions() & Converter::Out && conv->probeFile(&output)) {
                 outconv = conv;
                 break;
diff --git a/examples/corelib/serialization/convert/nullconverter.cpp b/examples/corelib/serialization/convert/nullconverter.cpp
index a88d10f454..02b844d2b5 100644
--- a/examples/corelib/serialization/convert/nullconverter.cpp
+++ b/examples/corelib/serialization/convert/nullconverter.cpp
@@ -8,33 +8,33 @@ using namespace Qt::StringLiterals;
 static NullConverter nullConverter;
 Converter *Converter::null = &nullConverter;
 
-QString NullConverter::name()
+QString NullConverter::name() const
 {
     return "null"_L1;
 }
 
-Converter::Direction NullConverter::directions()
+Converter::Direction NullConverter::directions() const
 {
     return Out;
 }
 
-Converter::Options NullConverter::outputOptions()
+Converter::Options NullConverter::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *NullConverter::optionsHelp()
+const char *NullConverter::optionsHelp() const
 {
     return nullptr;
 }
 
-bool NullConverter::probeFile(QIODevice *f)
+bool NullConverter::probeFile(QIODevice *f) const
 {
     Q_UNUSED(f);
     return false;
 }
 
-QVariant NullConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant NullConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     Q_UNUSED(f);
     Q_UNUSED(outputConverter);
@@ -42,7 +42,8 @@ QVariant NullConverter::loadFile(QIODevice *f, Converter *&outputConverter)
     return QVariant();
 }
 
-void NullConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void NullConverter::saveFile(QIODevice *f, const QVariant &contents,
+                             const QStringList &options) const
 {
     if (!options.isEmpty()) {
         fprintf(stderr, "Unknown option '%s' to null output. This format has no options.\n",
diff --git a/examples/corelib/serialization/convert/nullconverter.h b/examples/corelib/serialization/convert/nullconverter.h
index b2c69593f5..5a08abde59 100644
--- a/examples/corelib/serialization/convert/nullconverter.h
+++ b/examples/corelib/serialization/convert/nullconverter.h
@@ -10,13 +10,14 @@ class NullConverter : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // NULLCONVERTER_H
diff --git a/examples/corelib/serialization/convert/textconverter.cpp b/examples/corelib/serialization/convert/textconverter.cpp
index 4b1635b44c..f043daa257 100644
--- a/examples/corelib/serialization/convert/textconverter.cpp
+++ b/examples/corelib/serialization/convert/textconverter.cpp
@@ -44,34 +44,34 @@ static void dumpVariant(QTextStream &out, const QVariant &v)
     }
 }
 
-QString TextConverter::name()
+QString TextConverter::name() const
 {
     return "text"_L1;
 }
 
-Converter::Direction TextConverter::directions()
+Converter::Direction TextConverter::directions() const
 {
     return InOut;
 }
 
-Converter::Options TextConverter::outputOptions()
+Converter::Options TextConverter::outputOptions() const
 {
     return {};
 }
 
-const char *TextConverter::optionsHelp()
+const char *TextConverter::optionsHelp() const
 {
     return nullptr;
 }
 
-bool TextConverter::probeFile(QIODevice *f)
+bool TextConverter::probeFile(QIODevice *f) const
 {
     if (QFile *file = qobject_cast<QFile *>(f))
         return file->fileName().endsWith(".txt"_L1);
     return false;
 }
 
-QVariant TextConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant TextConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     if (!outputConverter)
         outputConverter = this;
@@ -94,7 +94,8 @@ QVariant TextConverter::loadFile(QIODevice *f, Converter *&outputConverter)
     return list;
 }
 
-void TextConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void TextConverter::saveFile(QIODevice *f, const QVariant &contents,
+                             const QStringList &options) const
 {
     if (!options.isEmpty()) {
         fprintf(stderr, "Unknown option '%s' to text output. This format has no options.\n",
diff --git a/examples/corelib/serialization/convert/textconverter.h b/examples/corelib/serialization/convert/textconverter.h
index 6bb713131c..a961f14113 100644
--- a/examples/corelib/serialization/convert/textconverter.h
+++ b/examples/corelib/serialization/convert/textconverter.h
@@ -10,13 +10,14 @@ class TextConverter : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // TEXTCONVERTER_H
diff --git a/examples/corelib/serialization/convert/xmlconverter.cpp b/examples/corelib/serialization/convert/xmlconverter.cpp
index 3461af46ee..f9da8cfe60 100644
--- a/examples/corelib/serialization/convert/xmlconverter.cpp
+++ b/examples/corelib/serialization/convert/xmlconverter.cpp
@@ -396,27 +396,27 @@ static void variantToXml(QXmlStreamWriter &xml, const QVariant &v)
     }
 }
 
-QString XmlConverter::name()
+QString XmlConverter::name() const
 {
     return "xml"_L1;
 }
 
-Converter::Direction XmlConverter::directions()
+Converter::Direction XmlConverter::directions() const
 {
     return InOut;
 }
 
-Converter::Options XmlConverter::outputOptions()
+Converter::Options XmlConverter::outputOptions() const
 {
     return SupportsArbitraryMapKeys;
 }
 
-const char *XmlConverter::optionsHelp()
+const char *XmlConverter::optionsHelp() const
 {
     return xmlOptionHelp;
 }
 
-bool XmlConverter::probeFile(QIODevice *f)
+bool XmlConverter::probeFile(QIODevice *f) const
 {
     if (QFile *file = qobject_cast<QFile *>(f)) {
         if (file->fileName().endsWith(".xml"_L1))
@@ -426,7 +426,7 @@ bool XmlConverter::probeFile(QIODevice *f)
     return f->isReadable() && f->peek(5) == "<?xml";
 }
 
-QVariant XmlConverter::loadFile(QIODevice *f, Converter *&outputConverter)
+QVariant XmlConverter::loadFile(QIODevice *f, const Converter *&outputConverter) const
 {
     if (!outputConverter)
         outputConverter = this;
@@ -442,7 +442,8 @@ QVariant XmlConverter::loadFile(QIODevice *f, Converter *&outputConverter)
     return v;
 }
 
-void XmlConverter::saveFile(QIODevice *f, const QVariant &contents, const QStringList &options)
+void XmlConverter::saveFile(QIODevice *f, const QVariant &contents,
+                            const QStringList &options) const
 {
     bool compact = false;
     for (const QString &s : options) {
diff --git a/examples/corelib/serialization/convert/xmlconverter.h b/examples/corelib/serialization/convert/xmlconverter.h
index 19bde6c7c6..51476e61e4 100644
--- a/examples/corelib/serialization/convert/xmlconverter.h
+++ b/examples/corelib/serialization/convert/xmlconverter.h
@@ -10,13 +10,14 @@ class XmlConverter : public Converter
 {
     // Converter interface
 public:
-    QString name() override;
-    Direction directions() override;
-    Options outputOptions() override;
-    const char *optionsHelp() override;
-    bool probeFile(QIODevice *f) override;
-    QVariant loadFile(QIODevice *f, Converter *&outputConverter) override;
-    void saveFile(QIODevice *f, const QVariant &contents, const QStringList &options) override;
+    QString name() const override;
+    Direction directions() const override;
+    Options outputOptions() const override;
+    const char *optionsHelp() const override;
+    bool probeFile(QIODevice *f) const override;
+    QVariant loadFile(QIODevice *f, const Converter *&outputConverter) const override;
+    void saveFile(QIODevice *f, const QVariant &contents,
+                  const QStringList &options) const override;
 };
 
 #endif // XMLCONVERTER_H