Blessed references can additionally provide their own hash functions and equality tests.
This RFC is probably premature. Any two objects whose HASH functions return different values will never resolve to the same hash table entry. Identical HASH functions are not sufficient for resolving to the same entry. If the outcome of the equality test changes while an object is in a hash table, the results are undefined. Note that the equality operator defined by the stored key is irrelevant, because the probe key's equality test is used during lookup.