Module rustc_data_structures::hashes
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rustc encodes a lot of hashes. If hashes are stored as u64
or u128
, a derive(Encodable)
will apply varint encoding to the hashes, which is less efficient than directly encoding the 8
or 16 bytes of the hash.
The types in this module represent 64-bit or 128-bit hashes produced by a StableHasher
.
Hash64
and Hash128
expose some utility functions to encourage users to not extract the inner
hash value as an integer type and accidentally apply varint encoding to it.
In contrast with Fingerprint
, users of these types cannot and should not attempt to construct
and decompose these types into constituent pieces. The point of these types is only to
connect the fact that they can only be produced by a StableHasher
to their
Encode
/Decode
impls.