Convert fprintf(stderr, ...); exit(EXIT_FAILURE); to qFatal(...)

The serialization conversion example used raw C's way to abort on
error; change to using Qt's way of doing the same. Likewise, convert
the various other uses of fprintf(stderr, ...) to qWarning() and of
printf(...) to qInfo().

Pick-to: 6.6 6.5
Task-number: QTBUG-111228
Change-Id: Ia8821d3c20f58f71c106028ec422ad473c11e164
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

7 files changed, 62 insertions, 91 deletions

diff --git a/examples/corelib/serialization/convert/cborconverter.cpp b/examples/corelib/serialization/convert/cborconverter.cpp
index a067fe5ea4..e0ff08f952 100644
--- a/examples/corelib/serialization/convert/cborconverter.cpp
+++ b/examples/corelib/serialization/convert/cborconverter.cpp
@@ -10,6 +10,7 @@
 #include <QCborStreamWriter>
 #include <QCborValue>
 #include <QDataStream>
+#include <QDebug>
 #include <QFile>
 #include <QFloat16>
 #include <QMetaType>
@@ -179,9 +180,8 @@ void CborDiagnosticDumper::saveFile(QIODevice *f, const QVariant &contents,
             }
         }
 
-        fprintf(stderr, "Unknown CBOR diagnostic option '%s'. Available options are:\n%s",
-                qPrintable(s), diagnosticHelp);
-        exit(EXIT_FAILURE);
+        qFatal("Unknown CBOR diagnostic option '%s'. Available options are:\n%s",
+               qPrintable(s), diagnosticHelp);
     }
 
     QTextStream out(f);
@@ -240,13 +240,12 @@ QVariant CborConverter::loadFile(QIODevice *f, const Converter *&outputConverter
     QCborValue contents = QCborValue::fromCbor(reader);
     qint64 offset = reader.currentOffset();
     if (reader.lastError()) {
-        fprintf(stderr, "Error loading CBOR contents (byte %lld): %s\n", offset,
-                qPrintable(reader.lastError().toString()));
-        fprintf(stderr, " bytes: %s\n",
-                (ptr ? mapped.mid(offset, 9) : f->read(9)).toHex(' ').constData());
-        exit(EXIT_FAILURE);
+        qFatal().nospace()
+            << "Error loading CBOR contents (byte " << offset
+            << "): " << reader.lastError().toString()
+            << "\n bytes: " << (ptr ? mapped.mid(offset, 9) : f->read(9));
     } else if (offset < mapped.size() || (!ptr && f->bytesAvailable())) {
-        fprintf(stderr, "Warning: bytes remaining at the end of the CBOR stream\n");
+        qWarning("Warning: bytes remaining at the end of the CBOR stream");
     }
 
     if (outputConverter == nullptr)
@@ -316,9 +315,8 @@ void CborConverter::saveFile(QIODevice *f, const QVariant &contents, const QStri
             }
         }
 
-        fprintf(stderr, "Unknown CBOR format option '%s'. Valid options are:\n%s",
-                qPrintable(s), cborOptionHelp);
-        exit(EXIT_FAILURE);
+        qFatal("Unknown CBOR format option '%s'. Valid options are:\n%s",
+               qPrintable(s), cborOptionHelp);
     }
     //! [4]
     QCborValue v =
diff --git a/examples/corelib/serialization/convert/datastreamconverter.cpp b/examples/corelib/serialization/convert/datastreamconverter.cpp
index 2da9cbd765..ce28fcb98e 100644
--- a/examples/corelib/serialization/convert/datastreamconverter.cpp
+++ b/examples/corelib/serialization/convert/datastreamconverter.cpp
@@ -80,10 +80,8 @@ QVariant DataStreamConverter::loadFile(QIODevice *f, const Converter *&outputCon
         outputConverter = &debugTextDumper;
 
     char c;
-    if (f->read(sizeof(signature) - 1) != signature || !f->getChar(&c) || (c != 'l' && c != 'B')) {
-        fprintf(stderr, "Could not load QDataStream file: invalid signature.\n");
-        exit(EXIT_FAILURE);
-    }
+    if (f->read(sizeof(signature) - 1) != signature || !f->getChar(&c) || (c != 'l' && c != 'B'))
+        qFatal("Could not load QDataStream file: invalid signature.");
 
     QDataStream ds(f);
     ds.setByteOrder(c == 'l' ? QDataStream::LittleEndian : QDataStream::BigEndian);
@@ -125,15 +123,13 @@ void DataStreamConverter::saveFile(QIODevice *f, const QVariant &contents,
                     continue;
                 }
 
-                fprintf(stderr, "Invalid version number '%s': must be a number from 1 to %d.\n",
-                        qPrintable(pair.last()), QDataStream::Qt_DefaultCompiledVersion);
-                exit(EXIT_FAILURE);
+                qFatal("Invalid version number '%s': must be a number from 1 to %d.",
+                       qPrintable(pair.last()), QDataStream::Qt_DefaultCompiledVersion);
             }
         }
 
-        fprintf(stderr, "Unknown QDataStream formatting option '%s'. Available options are:\n%s",
+        qFatal("Unknown QDataStream formatting option '%s'. Available options are:\n%s",
                 qPrintable(option), dataStreamOptionHelp);
-        exit(EXIT_FAILURE);
     }
 
     char c = order == QDataStream::LittleEndian ? 'l' : 'B';
diff --git a/examples/corelib/serialization/convert/jsonconverter.cpp b/examples/corelib/serialization/convert/jsonconverter.cpp
index b6a6a1dd40..6c307cdb8c 100644
--- a/examples/corelib/serialization/convert/jsonconverter.cpp
+++ b/examples/corelib/serialization/convert/jsonconverter.cpp
@@ -18,10 +18,8 @@ static const char jsonOptionHelp[] = "compact=no|yes              Use compact JS
 static QJsonDocument convertFromVariant(const QVariant &v)
 {
     QJsonDocument doc = QJsonDocument::fromVariant(v);
-    if (!doc.isObject() && !doc.isArray()) {
-        fprintf(stderr, "Could not convert contents to JSON.\n");
-        exit(EXIT_FAILURE);
-    }
+    if (!doc.isObject() && !doc.isArray())
+        qFatal("Could not convert contents to JSON.");
     return doc;
 }
 
@@ -75,9 +73,8 @@ QVariant JsonConverter::loadFile(QIODevice *f, const Converter *&outputConverter
     if (doc.isNull())
         doc = QJsonDocument::fromJson(f->readAll(), &error);
     if (error.error) {
-        fprintf(stderr, "Could not parse JSON content: offset %d: %s",
-                error.offset, qPrintable(error.errorString()));
-        exit(EXIT_FAILURE);
+        qFatal("Could not parse JSON content: offset %d: %s",
+               error.offset, qPrintable(error.errorString()));
     }
     if (outputConverter == null)
         return QVariant();
@@ -94,9 +91,8 @@ void JsonConverter::saveFile(QIODevice *f, const QVariant &contents,
         } else if (s == "compact=yes"_L1) {
             format = QJsonDocument::Compact;
         } else {
-            fprintf(stderr, "Unknown option '%s' to JSON output. Valid options are:\n%s",
-                    qPrintable(s), jsonOptionHelp);
-            exit(EXIT_FAILURE);
+            qFatal("Unknown option '%s' to JSON output. Valid options are:\n%s",
+                   qPrintable(s), jsonOptionHelp);
         }
     }
 
diff --git a/examples/corelib/serialization/convert/main.cpp b/examples/corelib/serialization/convert/main.cpp
index ede03dbe1d..a916175332 100644
--- a/examples/corelib/serialization/convert/main.cpp
+++ b/examples/corelib/serialization/convert/main.cpp
@@ -43,8 +43,8 @@ static const Converter *prepareConverter(QString format, Converter::Direction di
         stream->open(mode);
 
     if (!stream->isOpen()) {
-        fprintf(stderr, "Could not open \"%s\" for %s: %s\n",
-                qPrintable(stream->fileName()), dirn, qPrintable(stream->errorString()));
+        qFatal("Could not open \"%s\" for %s: %s",
+               qPrintable(stream->fileName()), dirn, qPrintable(stream->errorString()));
     } else if (format == "auto"_L1) {
         for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->directions().testFlag(direction) && conv->probeFile(stream))
@@ -54,21 +54,20 @@ static const Converter *prepareConverter(QString format, Converter::Direction di
             return nullptr;
 
         // Input format, however, we must know before we can call that:
-        fprintf(stderr, "Could not determine input format. Specify it with the -I option.\n");
+        qFatal("Could not determine input format. Specify it with the -I option.");
     } else {
         for (const Converter *conv : std::as_const(*availableConverters)) {
             if (conv->name() == format) {
                 if (!conv->directions().testFlag(direction)) {
-                    fprintf(stderr, "File format \"%s\" cannot be used for %s\n",
-                            qPrintable(format), dirn);
+                    qWarning("File format \"%s\" cannot be used for %s",
+                             qPrintable(format), dirn);
                     continue; // on the off chance there's another with the same name
                 }
                 return conv;
             }
         }
-        fprintf(stderr, "Unknown %s file format \"%s\"\n", dirn, qPrintable(format));
+        qFatal("Unknown %s file format \"%s\"", dirn, qPrintable(format));
     }
-    exit(EXIT_FAILURE);
     Q_UNREACHABLE_RETURN(nullptr);
 }
 
@@ -135,17 +134,16 @@ int main(int argc, char *argv[])
             if (conv->name() == format) {
                 const char *help = conv->optionsHelp();
                 if (help) {
-                    printf("The following options are available for format '%s':\n\n%s",
-                           qPrintable(format), help);
+                    qInfo("The following options are available for format '%s':\n\n%s",
+                          qPrintable(format), help);
                 } else {
-                    printf("Format '%s' supports no options.\n", qPrintable(format));
+                    qInfo("Format '%s' supports no options.", qPrintable(format));
                 }
                 return EXIT_SUCCESS;
             }
         }
 
-        fprintf(stderr, "Unknown file format '%s'\n", qPrintable(format));
-        return EXIT_FAILURE;
+        qFatal("Unknown file format '%s'", qPrintable(format));
     }
 
     QStringList files = parser.positionalArguments();
diff --git a/examples/corelib/serialization/convert/nullconverter.cpp b/examples/corelib/serialization/convert/nullconverter.cpp
index aababe6779..7c499efd73 100644
--- a/examples/corelib/serialization/convert/nullconverter.cpp
+++ b/examples/corelib/serialization/convert/nullconverter.cpp
@@ -46,9 +46,8 @@ 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",
-                qPrintable(options.first()));
-        exit(EXIT_FAILURE);
+        qFatal("Unknown option '%s' to null output. This format has no options.",
+               qPrintable(options.first()));
     }
 
     Q_UNUSED(f);
diff --git a/examples/corelib/serialization/convert/textconverter.cpp b/examples/corelib/serialization/convert/textconverter.cpp
index 2df2423bb6..3bfd806bf4 100644
--- a/examples/corelib/serialization/convert/textconverter.cpp
+++ b/examples/corelib/serialization/convert/textconverter.cpp
@@ -98,9 +98,8 @@ 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",
-                qPrintable(options.first()));
-        exit(EXIT_FAILURE);
+        qFatal("Unknown option '%s' to text output. This format has no options.",
+               qPrintable(options.first()));
     }
 
     QTextStream out(f);
diff --git a/examples/corelib/serialization/convert/xmlconverter.cpp b/examples/corelib/serialization/convert/xmlconverter.cpp
index 11d298e04c..ef71fecb9f 100644
--- a/examples/corelib/serialization/convert/xmlconverter.cpp
+++ b/examples/corelib/serialization/convert/xmlconverter.cpp
@@ -49,9 +49,8 @@ static QVariantList listFromXml(QXmlStreamReader &xml, Converter::Options option
             break;
         }
 
-        fprintf(stderr, "%lld:%lld: Invalid XML %s '%s'.\n", xml.lineNumber(), xml.columnNumber(),
-                qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML %s '%s'.", xml.lineNumber(), xml.columnNumber(),
+               qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
     }
 
     xml.readNext();
@@ -91,9 +90,8 @@ static VariantOrderedMap::value_type mapEntryFromXml(QXmlStreamReader &xml,
             break;
         }
 
-        fprintf(stderr, "%lld:%lld: Invalid XML %s '%s'.\n", xml.lineNumber(), xml.columnNumber(),
-                qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML %s '%s'.", xml.lineNumber(), xml.columnNumber(),
+               qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
     }
 
     return { key, value };
@@ -135,9 +133,8 @@ static QVariant mapFromXml(QXmlStreamReader &xml, Converter::Options options)
             break;
         }
 
-        fprintf(stderr, "%lld:%lld: Invalid XML %s '%s'.\n", xml.lineNumber(), xml.columnNumber(),
-                qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML %s '%s'.", xml.lineNumber(), xml.columnNumber(),
+               qPrintable(xml.tokenString()), qPrintable(xml.name().toString()));
     }
 
     xml.readNext();
@@ -154,9 +151,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
     if (name == "map"_L1)
         return mapFromXml(xml, options);
     if (name != "value"_L1) {
-        fprintf(stderr, "%lld:%lld: Invalid XML key '%s'.\n",
-                xml.lineNumber(), xml.columnNumber(), qPrintable(name.toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML key '%s'.",
+               xml.lineNumber(), xml.columnNumber(), qPrintable(name.toString()));
     }
 
     QXmlStreamAttributes attrs = xml.attributes();
@@ -169,9 +165,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
         if (xml.isCDATA() || xml.isCharacters() || xml.isEndElement())
             break;
 
-        fprintf(stderr, "%lld:%lld: Invalid XML %s '%s'.\n", xml.lineNumber(), xml.columnNumber(),
-                qPrintable(xml.tokenString()), qPrintable(name.toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML %s '%s'.", xml.lineNumber(), xml.columnNumber(),
+               qPrintable(xml.tokenString()), qPrintable(name.toString()));
     }
 
     QStringView text = xml.text();
@@ -191,9 +186,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
             // let's see floating point
             double d = text.toDouble(&ok);
             if (!ok) {
-                fprintf(stderr, "%lld:%lld: Invalid XML: could not interpret '%s' as a number.\n",
-                        xml.lineNumber(), xml.columnNumber(), qPrintable(text.toString()));
-                exit(EXIT_FAILURE);
+                qFatal("%lld:%lld: Invalid XML: could not interpret '%s' as a number.",
+                       xml.lineNumber(), xml.columnNumber(), qPrintable(text.toString()));
             }
             result = d;
         }
@@ -207,9 +201,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
         } else if (encoding.isEmpty() || encoding == "base64"_L1) {
             result = QByteArray::fromBase64(data);
         } else {
-            fprintf(stderr, "%lld:%lld: Invalid XML: unknown encoding '%s' for bytes.\n",
-                    xml.lineNumber(), xml.columnNumber(), qPrintable(encoding.toString()));
-            exit(EXIT_FAILURE);
+            qFatal("%lld:%lld: Invalid XML: unknown encoding '%s' for bytes.",
+                   xml.lineNumber(), xml.columnNumber(), qPrintable(encoding.toString()));
         }
     } else if (type == "string"_L1) {
         result = text.toString();
@@ -228,9 +221,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
             } else if (c == '0') {
                 ++n;
             } else if (!c.isSpace()) {
-                fprintf(stderr, "%lld:%lld: Invalid XML: invalid bit string '%s'.\n",
-                        xml.lineNumber(), xml.columnNumber(), qPrintable(text.toString()));
-                exit(EXIT_FAILURE);
+                qFatal("%lld:%lld: Invalid XML: invalid bit string '%s'.",
+                       xml.lineNumber(), xml.columnNumber(), qPrintable(text.toString()));
             }
         }
         ba.resize(n);
@@ -248,16 +240,14 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
         else
             id = QMetaType::fromName(type.toLatin1()).id();
         if (id == QMetaType::UnknownType) {
-            fprintf(stderr, "%lld:%lld: Invalid XML: unknown type '%s'.\n",
-                    xml.lineNumber(), xml.columnNumber(), qPrintable(type.toString()));
-            exit(EXIT_FAILURE);
+            qFatal("%lld:%lld: Invalid XML: unknown type '%s'.",
+                   xml.lineNumber(), xml.columnNumber(), qPrintable(type.toString()));
         }
 
         result = text.toString();
         if (!result.convert(QMetaType(id))) {
-            fprintf(stderr, "%lld:%lld: Invalid XML: could not parse content as type '%s'.\n",
-                    xml.lineNumber(), xml.columnNumber(), qPrintable(type.toString()));
-            exit(EXIT_FAILURE);
+            qFatal("%lld:%lld: Invalid XML: could not parse content as type '%s'.",
+                   xml.lineNumber(), xml.columnNumber(), qPrintable(type.toString()));
         }
     }
 
@@ -266,9 +256,8 @@ static QVariant variantFromXml(QXmlStreamReader &xml, Converter::Options options
     } while (xml.isComment() || xml.isWhitespace());
 
     if (!xml.isEndElement()) {
-        fprintf(stderr, "%lld:%lld: Invalid XML %s '%s'.\n", xml.lineNumber(), xml.columnNumber(),
-                qPrintable(xml.tokenString()), qPrintable(name.toString()));
-        exit(EXIT_FAILURE);
+        qFatal("%lld:%lld: Invalid XML %s '%s'.", xml.lineNumber(), xml.columnNumber(),
+               qPrintable(xml.tokenString()), qPrintable(name.toString()));
     }
 
     xml.readNext();
@@ -388,8 +377,7 @@ static void variantToXml(QXmlStreamWriter &xml, const QVariant &v)
                     xml.writeAttribute(typeString, QString::fromLatin1(typeName));
                     xml.writeCharacters(copy.toString());
                 } else {
-                    fprintf(stderr, "XML: don't know how to serialize type '%s'.\n", typeName);
-                    exit(EXIT_FAILURE);
+                    qFatal("XML: don't know how to serialize type '%s'.", typeName);
                 }
             }
         }
@@ -435,10 +423,8 @@ QVariant XmlConverter::loadFile(QIODevice *f, const Converter *&outputConverter)
     QXmlStreamReader xml(f);
     xml.readNextStartElement();
     QVariant v = variantFromXml(xml, outputConverter->outputOptions());
-    if (xml.hasError()) {
-        fprintf(stderr, "XML error: %s", qPrintable(xml.errorString()));
-        exit(EXIT_FAILURE);
-    }
+    if (xml.hasError())
+        qFatal("XML error: %s", qPrintable(xml.errorString()));
 
     return v;
 }
@@ -453,9 +439,8 @@ void XmlConverter::saveFile(QIODevice *f, const QVariant &contents,
         } else if (s == "compact=yes"_L1) {
             compact = true;
         } else {
-            fprintf(stderr, "Unknown option '%s' to XML output. Valid options are:\n%s",
-                    qPrintable(s), xmlOptionHelp);
-            exit(EXIT_FAILURE);
+            qFatal("Unknown option '%s' to XML output. Valid options are:\n%s",
+                   qPrintable(s), xmlOptionHelp);
         }
     }