QXmlStreamReader - High Memory Consumption with QByteArray

When using a QXmlStreamReader with a QByteArray as input, the whole QByteArray gets copied internally when calling QXmlStreamReader::readNextStartElement() for the first time.

This is a very serious issue when using big input xml data (> 50 MB).

The QByteArray gets copied in:

ushort QXmlStreamReaderPrivate::getChar_helper() { // ...
   // line 1526
  decoder->toUnicode(&readBuffer, rawReadBuffer.data(), nbytesread);
}

My suggestion is to use:

  decoder->toUnicode(&readBuffer, rawReadBuffer.constData(), nbytesread);

instead. QSharedDataPointer should not copy the byte array then.

Parsing without copying is quite crucial for our application.