[tveita]

NaiveHasher (declared as "struct NaiveHasher(u64);") is a tuple with one 64-bit field named "0". (Tuple fields are implitly named as 0, 1, 2 ...)

It implements a very simple hashing function for 64-bit numbers, each hashed number n overwrites the state with n xor (n >> 7). finish() will return the last written state.

This seems to work okay since the hashed structure "Code" contains exactly one 64-bit field.

I don't know if it's fishy, but it's certainly very custom. For a generic hashing implementation you'd at least want to mix in the previous state. I assume it was done more for brevity than performance though.