We should rename std::hash::RandomSipHasher to something more generic

[erickt]

Right now HashMaps are tied to a specific algorithm implementation, std::hash::RandomSipHasher. While I believe SipHash is considered cryptographically secure, if it were ever to be broken it could be painful transitioning everyone into a new Hasher. Instead, I suggest we change it's name now to save us from headaches later on. Some possible names:

• DefaultHasher
• StandardHasher
• StdHasher
• RandomHasher

[sfackler]

This seems pretty reasonable to me, but we should probably explicitly specify that it's randomly keyed.

[aturon]

(This has been nominated for the 1.0 milestone due to long-term security concerns.)

[Gankra]

I think the name should reflect that it is chosen specifically for its security properties, and not, say, performance properties (which seem to be mediocre). Also I do not think we should imply that it is a good secure or default choice for other hashing tasks. It is specifically good for HashMaps.

SecureHashmapHasher?

[pczarn]

I prefer UnpredictableHasher, RandomHasher. RandomizedHasher.

Also I do not think we should imply that it is a good secure or default choice for other hashing tasks

Won't SipHash be necessary for some other collections, such as HAMT?

[Gankra]

Oh I assumed this was just going to be some kind of newtype/alias for RandomSipHasher (which is simply a nice, accurate, name). So HAMT would also alias it.

[alexcrichton]

Fixed in #20654

• RandomSipHasher was renamed to std::collections::hash_map::RandomState
• The default hasher for hash maps is now called std::collections::hash_map::Hasher