invokeMethod or QMetaMethod->invoke() not possible for more than 3 arguments

I noticed the following when trying to invoke object methods directly from PySide6 using QMetaObject::invokeMethod() and QMetaMethod::invoke() in a generic way. The context is to call an abitrary method this way, which may have various return types:

• Q_ARG and Q_RETURN_ARG yield QGeneric[Return]ArgumentHolders, respectively. There is no direct method to get the Pythonic value back out of these structures.
• The Holders can be converted to QGenericArgument and QGenericReturnArgument (which we also can't get the Pythonic value back out of).
• QMetaObject::invokeMethod with the ...Holder types offers exactly what I need here: a way to call a method and yield an arbitrary Python object (converts the generic return argument back to the correct Pythonic object type under the hood"). But:
  • This invokeMethod variant only allows for max. 3 arguments to be passed, whereas the non-...Holder variants offer up to about 10.
  • FYI, the return arg conversion is implemented in 
    static PyObject *invokeMethodHelper (qtcore.cpp)
  • This seems to be the only method in the PySide API that does this automatic conversion.
• QMetaMethod::invoke doesn't have any interface which offers the automatic return type conversion.

Thus, it seems to me it is not possible to invoke a method generically if it has more than 3 arguments and a return value.

My suggestion would be to offer a direct conversion function which takes a QGeneric[Return]Argument and yields the correct Python value. Basically implementing the same conversion which is already being done now in static PyObject *invokeMethodHelper (qtcore.cpp).

This way, it can also be used with QMetaMethod, which I am assuming is faster than invokeMethod by name.