Qt qInstallMessageHandler encoding

Question

I have a problem with Russian text in debug log when I implemented my custom log handler via qInstallMessageHandler function. Currently, my code is:

void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg) {

    QByteArray localMsg = msg.toLatin1();

    QString stringType;
    switch (type) {
    case QtDebugMsg:
        stringType = "D";
        break;
    case QtWarningMsg:
        stringType = "W";
        break;
    case QtCriticalMsg:
        stringType = "C";
        break;
    case QtFatalMsg:
        stringType = "Fatal";
        break;
    default:
        stringType = "Unknown";
    }

    QString logString = QString("[%1] %2:%3 - %4\n")
            .arg(stringType)
            .arg(context.function)
            .arg(context.line)
            .arg(localMsg.constData());

    if (__logFile.isOpen()) {
        QTextStream stream(&__logFile);
        stream << logString;
    }

    QTextStream stderrStream(stderr, QIODevice::WriteOnly);

    stderrStream<<logString;

    if (type == QtFatalMsg) {
        abort();
    }
} 

And in main() function:

QTextCodec::setCodecForLocale(QTextCodec::codecForName("UTF-8"));
createLogFile();

qInstallMessageHandler(myMessageOutput);

qDebug()<<"Hi привет";

But instead of "Hi привет" I got

[D] int main(int, char**):131 - Hi ??????

in qt creator log. I tried to user Windows-1251 codec, but it don't change anything.

Answer 1

The problem is here:

QByteArray localMsg = msg.toLatin1();

To quote the documentation for QString::toLatin1() :

Returns a Latin-1 representation of the string as a QByteArray.

The returned byte array is undefined if the string contains non-Latin1 characters. Those characters may be suppressed or replaced with a question mark .

Emphasis mine.

The good news is there's no reason you need to call this method. Converting the contents of msg from a QString to a QByteArray is completely unnecessary here.