Change DefaultHashBuilder to an opaque newtype
#643
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| /// Default hasher for [`HashMap`](crate::HashMap) and [`HashSet`](crate::HashSet). | ||
| #[cfg(feature = "default-hasher")] | ||
| #[derive(Clone)] |
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Is it really necessary for this to implement Clone? I don't think it every makes sense to clone a Hasher.
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It's probably not necessary, but FWIW both FoldHasher and std::hash::DefaultHasher do implement Clone.
(std also implements Debug and Default, but FoldHasher does not.)
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std added Clone in rust-lang/rust#42799, without much discussion.
This hides the underlying hasher as an implementation detail, so it's no longer a public dependency. A newtype `DefaultHasher` is also added here to wrap the underlying `<_ as BuildHasher>::Hasher` type. This is a breaking change now, requiring a semver bump, but it will allow later changes to the hasher without breaking.
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Hmm apparently updating the version number will cause release-plz to immediately publish a new version of the crate. |
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Sorry, I didn't know it would do that. Maybe this is worth a warning comment in It seems I should have used one of these breaking change indicators in my commit message instead: |
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This hides the underlying hasher as an implementation detail, so it's no
longer a public dependency. A newtype
DefaultHasheris also added hereto wrap the underlying
<_ as BuildHasher>::Hashertype.This is a breaking change now, requiring a semver bump, but it will
allow later changes to the hasher without breaking.