You can identify some places changes are possible, but the problem is fundamentally unprovable, because of the Halting problem. You can't just hand-wave that away by saying, "we can use tricks to get 95% coverage." Ok, but if the type graph is not a provable entity that you can derive without simulating the program, you've sacrificed the fundamental point of C-style types, and that means you can never operate on them in the same way you can with C.