Python 3.7
Qt 5.14.2 (x86_64-little_endian-lp64 shared (dynamic) release build; by GCC 5.3.1 20160406 (Red Hat 5.3.1-6))

signalInstanceConnect PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 1 <("method", 0x45000 [gc], <unknown>)>)
getArgsFromSignature dataReceived(QObject*) ("QObject*")
getArgsFromSignature dataReceived(QObject*) ("QObject*")
getCallbackSignature dataReceived(QObject*) "testSlot(QObject*)"
> qt_metacall Controller(0x1b705a0) 0 6
> callMethod 6
callMethod call PyObject("method", 0xc5000 [gc], <unknown>)
callPythonMetaMethod call PyObject("method", 0xc5000 [gc], <unknown>) isShortCuit=0
parseArguments   ()
callPythonMetaMethod PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 0 <>)
updateSourceObject PyObject("Data", 0x5601 [heaptype] [base] [gc], <unknown>)
signalInstanceEmit PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 1 <("Data", 0x5601 [heaptype] [base] [gc], <unknown>)>)
signalInstanceEmit source=PyObject("str", 0x100c1400 [base] [unicode], "2dataReceived(QObject*)") method=PyObject("builtin_function_or_method", 0xc5000 [gc], <unknown>) pyargs=PyObject("list", 0x20c5400 [base] [gc] [list], 2 <("str", 0x100c1400 [base] [unicode], "2dataReceived(QObject*)"), ("Data", 0x5601 [heaptype] [base] [gc], <unknown>)>)
emitSignal Controller(0x1b705a0) 2dataReceived(QObject*)
    args= PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 1 <("Data", 0x5601 [heaptype] [base] [gc], <unknown>)>)
emitSignal  idx =  5  isShortCircuit= false
call Controller(0x1b705a0) "dataReceived(QObject*)" ("QObject*")
call PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 1 <("Data", 0x5601 [heaptype] [base] [gc], <unknown>)>)
call 0 ""
call 1 "QObject*"
call 1 "QObject*" typeId= 39 pythonTypeIsObjectType= true
call 1 PyObject("Data", 0x5601 [heaptype] [base] [gc], <unknown>)
call 1 qvar= QVariant(Invalid) 0x1d8d538
call i= 2 numArgs= 2 true
> qt_metacall Controller(0x1b705a0) 0 5
> callMethod 5
callMethod  emit sig 
qml: QML reached
> qt_metacall Controller(0x1b705a0) 0 7
> callMethod 7
callMethod testSlot PyObject("method", 0xc5000 [gc], <unknown>)
callPythonMetaMethod testSlot PyObject("method", 0xc5000 [gc], <unknown>) isShortCuit=0
parseArguments   ("QObject*")
parseArguments 0 PyObject("Data", 0x5601 [heaptype] [base] [gc], <unknown>)
callPythonMetaMethod PyObject("tuple", 0x40c5400 [base] [gc] [tuple], 1 <("Data", 0x5601 [heaptype] [base] [gc], <unknown>)>)
< qt_metacall Controller(0x1b705a0) rets -9
< callMethod
< qt_metacall Controller(0x1b705a0) rets -9
call QMetaObject::metacall rets -9
emitSignal Controller(0x1b705a0) dataReceived(QObject*)  rets =  true
< qt_metacall Controller(0x1b705a0) rets -9