Created attachment 455 [details]
example for this bug

QDataStream allows to write Python string (str) into it:

    ba = QByteArray()
    stream = QDataStream(ba, QIODevice.WriteOnly)
    stream << "hello"

After that `ba' contains null-bytes:
    print [c for c in ba]
['\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00',
'\x00', '\x00', '\x00', '\x00', '\x00', '\x00', '\x00']

So following read of string/QByteArray silently fails:

    read_stream = QDataStream(ba, QIODevice.ReadOnly)
    res = ""
    read_stream >> res

res remains equal to empty string.

Please see attached example based on
pyside-git\tests\QtCore\qdatastream_test.py unit-test.

QtCore.QDataStream should support `<< str(...)' operation (like PyQt does) or
at least give user warning/error when someone tries to do such unsupported
operation.

P.S. As workaround I saw in unit-test that working way of passing string
through QDataStream is to wrap all string items in QByteArray:

    ba = QByteArray()
    stream = QDataStream(ba, QIODevice.WriteOnly)
    stream << QByteArray("hello")

    read_stream = QDataStream(ba, QIODevice.ReadOnly)
    res = QByteArray()
    read_stream >> res