=======================================================================
FIXED compiling with QT_NO_CAST_TO_ASCII not possible
========================================================================
DEFINES += QT_NO_CAST_TO_ASCII

g++ -c -pipe -march=native -O2 -Wall -W -D_REENTRANT -DQT_NO_CAST_FROM_BYTEARRAY -DQT_NO_CAST_TO_ASCII -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtNetwork -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -o trackerclient.o trackerclient.cpp
trackerclient.cpp: In member function 'void TrackerClient::fetchPeerList()':
trackerclient.cpp:122: error: no match for 'operator+=' in 'query += passkey'
/usr/include/qt4/QtCore/qbytearray.h:486: note: candidates are: QByteArray& QByteArray::operator+=(char)
/usr/include/qt4/QtCore/qbytearray.h:488: note: QByteArray& QByteArray::operator+=(const char*)
/usr/include/qt4/QtCore/qbytearray.h:490: note: QByteArray& QByteArray::operator+=(const QByteArray&)
trackerclient.cpp:123: error: no match for 'operator+=' in 'query = operator(const char*, const QString&)(((const QString&)((const QString*)(& encodedSum))))'
/usr/include/qt4/QtCore/qbytearray.h:486: note: candidates are: QByteArray& QByteArray::operator+=(char)
/usr/include/qt4/QtCore/qbytearray.h:488: note: QByteArray& QByteArray::operator+=(const char*)
/usr/include/qt4/QtCore/qbytearray.h:490: note: QByteArray& QByteArray::operator+=(const QByteArray&)
make: *** [trackerclient.o] Error 1

i fixed this with
query += "info_hash=" + encodedSum.toLatin1();
not sure if that is correct

========================================================================
FIXED compiling with QT_NO_CAST_FROM_BYTEARRAY not possible
========================================================================
DEFINES += QT_NO_CAST_FROM_BYTEARRAY

============= metainfo.cpp ============
/usr/include/qt4/QtCore/qbytearray.h: In member function 'bool MetaInfo::parse(const QByteArray&)':
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:106: error: within this context
metainfo.cpp:106: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:106: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:111: error: within this context
metainfo.cpp:111: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:111: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:120: error: within this context
metainfo.cpp:120: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:120: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:128: error: within this context
metainfo.cpp:128: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:128: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:137: error: within this context
metainfo.cpp:137: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:137: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
metainfo.cpp:139: error: within this context
metainfo.cpp:139: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
metainfo.cpp:139: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'

============= trackerclient.cpp ============
/usr/include/qt4/QtCore/qbytearray.h: In member function 'void TrackerClient::httpRequestDone(bool)':
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
trackerclient.cpp:185: error: within this context
trackerclient.cpp:185: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
trackerclient.cpp:185: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
trackerclient.cpp:191: error: within this context
trackerclient.cpp:191: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
trackerclient.cpp:191: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
trackerclient.cpp:215: error: within this context
trackerclient.cpp:215: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
trackerclient.cpp:215: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
/usr/include/qt4/QtCore/qbytearray.h:364: error: 'QByteArray::operator QNoImplicitBoolCast() const' is private
trackerclient.cpp:216: error: within this context
trackerclient.cpp:216: error: invalid conversion from 'QNoImplicitBoolCast' to 'const char*'
trackerclient.cpp:216: error: initializing argument 1 of 'static QString QString::fromUtf8(const char*, int)'
make: *** [trackerclient.o] Error 1

== fix ==
fixing is easy, as it requires a constData() explicit cast

== the torrent client status after this fix ==
i was able to download with 16kb/s, so it seem to work