Sorry, it's my error, the compile error is because of call_method<>, and call_method<void> is OK!

 

   struct Base
    {
        virtual int f() = 0;
        virtual Base* clone() = 0;

        virtual void g() = 0;
    };

 

    struct BaseWrap : Base
    {
        BaseWrap(PyObject* self_)
            : self(self_) {}
        int f() { return call_method<int>(self, "f"); }

        file://void g() {call_method<>(self, "g"); }//compile error       

        void g() {call_method<void>(self, "g"); }//ok
        Base* clone(){ return call_method<Base*>(self, "clone");}
        PyObject* self;
    };