[ CCode ( has_target = false ) ]
public delegate void SignalCVaMarshaller (Closure closure, Value? return_value, TypeInstance instance, va_list args, void* marshal_data, Type[] param_types)

This is the signature of va_list marshaller functions, an optional marshaller that can be used in some situations to avoid marshalling the signal argument into GValues.

Namespace: GLib
Package: gobject-2.0