void fn_prototype_t(int a) {}
void fn_prototype_x(int a) {}
void fn_prototype_c(int a, int b) {}

void test_funcref()
{
    funcref<fn_prototype_t> ref;
    ref = fn_prototype_t;
    ref = fn_prototype_x;
    ref = fn_prototype_c;
    ref(1, 1);
    ref(ref(1));

    ref = ref;
}