Ye but I would just want the possibility for the simpler syntax like the GCC extension for C where you can do:

    typedef void fp_t();
    void foo(fp_t fp)
    {
        fp();
    }

    int square(int num) {

        void square_nested() 
        {
            num = num * num;
        }

        foo(square_nested);

        return num;
    }

That would work as long as you don't need copy capture.