A<T> and A<U> get the same hash

[joonazan]

I realized this while writing basically the same functionality, just compile time instead of runtime. If this is a problem, you'll have to include the typehash of T in A<T>'s hash.

BTW, your type_hash function would be a lot simpler if you hashed module_path!() and the name of the type. That should be enough to uniquely identify a type.