QXmlStreamReader::characterOffset() returns the wrong value for the first tag when the encoding is not UTF-8

#include <QXmlStreamReader> 
#include <QDebug> 
 
int main() 
{ 
        // If you uncomment the <?xml> header characterOffset() works as expected 
        const char data[] = //"<?xml version='1.0' encoding='UTF-8'?>" 
                                                "<Tag1 attribute='X'><Tag2><Tag3>Y</Tag3></Tag2></Tag1>"; 
 
        QXmlStreamReader xml(data); 
        int offset=0; 
        while(!xml.atEnd()) 
        { 
                xml.readNext(); 
                if(xml.isStartElement()) 
                { 
                        qDebug() << data; 
                        qDebug() << (QByteArray(offset, ' ')+"^").constData(); 
                } 
                offset=xml.characterOffset(); 
        } 
}