invalid use of incomplete type

Question

I\'m trying to use a typedef from a subclass in my project, I\'ve isolated my problem in the example below.

Does anyone know where I\'m going wrong?

Answer 1

You need to use a pointer or a reference as the proper type is not known at this time the compiler can not instantiate it.

Instead try:

void action(const typename Subclass::mytype &var) {
            (static_cast(this))->do_action();
    }