C ++ «нет совпадения для вызова» ошибка в sigc :: mem_fun

я использую sigc::mem_fun подключить функцию-обработчик, которая является членом класса, к событию GTKMM. Я звоню sigc::mem_fun из того же класса функция-обработчик объявлена ​​в.

// Interface.h

class Interface {
public:
Interface(...);
// ...
private:
Gtk::ComboBoxText *optionChoiceComboBoxText = nullptr; //Initialized in constructor
Gtk::Switch optionControlSwitch;

void optionChangedHandler();

void switchHandler();
// ...
};

// Interface.cpp

Interface::Interface(...) {
// ...
optionChoiceComboBoxText->signal_changed().connect(sigc::mem_fun(*this, &Interface::optionChangedHandler));
optionControlSwitch.signal_state_changed().connect(sigc::mem_fun(*this, &Interface::switchHandler)); // Error is here
}void Interface::optionChangedHandler() {
// Do something
}

void Interface::switchHandler() {
// Do something
}

Это ошибка:

In file included from /usr/include/sigc++-2.0/sigc++/functors/slot.h:7:0,
from /usr/include/sigc++-2.0/sigc++/signal_base.h:27,
from /usr/include/sigc++-2.0/sigc++/signal.h:8,
from /usr/include/sigc++-2.0/sigc++/sigc++.h:86,
from /usr/include/glibmm-2.4/glibmm/thread.h:51,
from /usr/include/glibmm-2.4/glibmm.h:87,
from /usr/include/giomm-2.4/giomm.h:23,
from /home/crefrod/RNS/src/GUI/Interface.cpp:5:
/usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h: In instantiation of ‘typename sigc::adaptor_functor<T_functor>::deduce_result_type<T_arg1>::type sigc::adaptor_functor<T_functor>::operator()(T_arg1) const [with T_arg1 = const Gtk::StateType&; T_functor = sigc::bound_mem_functor0<void, Interface>; typename sigc::adaptor_functor<T_functor>::deduce_result_type<T_arg1>::type = void]’:
/usr/include/sigc++-2.0/sigc++/functors/slot.h:142:20:   required from ‘static T_return sigc::internal::slot_call1<T_functor, T_return, T_arg1>::call_it(sigc::internal::slot_rep*, sigc::type_trait_take_t<T_arg3>) [with T_functor = sigc::bound_mem_functor0<void, Interface>; T_return = void; T_arg1 = Gtk::StateType; sigc::type_trait_take_t<T_arg3> = const Gtk::StateType&]’
/usr/include/sigc++-2.0/sigc++/functors/slot.h:149:37:   required from ‘static void* (* sigc::internal::slot_call1<T_functor, T_return, T_arg1>::address())(void*) [with T_functor = sigc::bound_mem_functor0<void, Interface>; T_return = void; T_arg1 = Gtk::StateType; sigc::internal::hook = void* (*)(void*)]’
/usr/include/sigc++-2.0/sigc++/functors/slot.h:584:90:   required from ‘sigc::slot1<T_return, T_arg1>::slot1(const T_functor&) [with T_functor = sigc::bound_mem_functor0<void, Interface>; T_return = void; T_arg1 = Gtk::StateType]’
/usr/include/sigc++-2.0/sigc++/functors/slot.h:1731:26:   required from ‘sigc::slot<T_return, T_arg1, sigc::nil, sigc::nil, sigc::nil, sigc::nil, sigc::nil, sigc::nil>::slot(const T_functor&) [with T_functor = sigc::bound_mem_functor0<void, Interface>; T_return = void; T_arg1 = Gtk::StateType]’
/home/crefrod/RNS/src/GUI/Interface.cpp:38:103:   required from here
/usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:89:30: error: no match for call to ‘(sigc::bound_mem_functor0<void, Interface>) (const Gtk::StateType&)’
{ return functor_(_A_arg1); }
^
In file included from /usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:9:0,
from /usr/include/sigc++-2.0/sigc++/functors/slot.h:7,
from /usr/include/sigc++-2.0/sigc++/signal_base.h:27,
from /usr/include/sigc++-2.0/sigc++/signal.h:8,
from /usr/include/sigc++-2.0/sigc++/sigc++.h:86,
from /usr/include/glibmm-2.4/glibmm/thread.h:51,
from /usr/include/glibmm-2.4/glibmm.h:87,
from /usr/include/giomm-2.4/giomm.h:23,
from /home/crefrod/RNS/src/GUI/Interface.cpp:5:
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1786:12: note: candidate: T_return sigc::bound_mem_functor0<T_return, T_obj>::operator()() const [with T_return = void; T_obj = Interface]
T_return operator()() const
^
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1786:12: note:   candidate expects 0 arguments, 1 provided
In file included from /usr/include/sigc++-2.0/sigc++/functors/slot.h:7:0,
from /usr/include/sigc++-2.0/sigc++/signal_base.h:27,
from /usr/include/sigc++-2.0/sigc++/signal.h:8,
from /usr/include/sigc++-2.0/sigc++/sigc++.h:86,
from /usr/include/glibmm-2.4/glibmm/thread.h:51,
from /usr/include/glibmm-2.4/glibmm.h:87,
from /usr/include/giomm-2.4/giomm.h:23,
from /home/crefrod/RNS/src/GUI/Interface.cpp:5:
/usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:89:30: error: return-statement with a value, in function returning 'void' [-fpermissive]
{ return functor_(_A_arg1); }
^

Еще одна странная вещь — почему компилятор выдает ошибку на второй sigc::mem_fun вызов. Это просто, как это работает, или это как-то связано с тем фактом, что первый вызов выполняется для указателя, а второй — для самого объекта?