Relax constraint in hash_map::EntryRef insertion methods K: From<&Q> to &Q: Into<K> #611
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Currently
EntryRef::or_insert*
methods have constraintK: From<&Q>
which is required to construct "owned" key from "borrowed" key during insertion operation.Rust documentation recommends not to use
From
as trait constraint, and instead prefer to use reversedInto
trait constraint:https://doc.rust-lang.org/std/convert/trait.From.html
Changing constraint
K: From<&Q>
to&Q: Into<K>
extends support of insert operation to additional cases whereK
does not implement traitFrom<&Q>
, but&Q
does implement traitInto<K>
.API compatibility:
&Q: Into<K>
is a strict superset ofK: From<&Q>
(because of blanket implementation https://doc.rust-lang.org/std/convert/trait.Into.html#impl-Into%3CU%3E-for-T), so this change does not break existing hashbrown API compatibility; all existing code will work with new trait constraints.