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Remove and disallow HashStable impl of HashMap.

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This commit is contained in:
Michael Woerister 2024-03-27 14:57:01 +01:00
parent a50490c579
commit 7e4bc4a373
1 changed files with 2 additions and 46 deletions
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48
compiler/rustc_data_structures/src/stable_hasher.rs
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@ -684,26 +684,11 @@ fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
impl_stable_traits_for_trivial_type!(::std::path::Path); impl_stable_traits_for_trivial_type!(::std::path::Path);
impl_stable_traits_for_trivial_type!(::std::path::PathBuf); impl_stable_traits_for_trivial_type!(::std::path::PathBuf);
impl<K, V, R, HCX> HashStable<HCX> for ::std::collections::HashMap<K, V, R> // It is not safe to implement HashStable for HashSet, HashMap or any other collection type
where
K: ToStableHashKey<HCX> + Eq,
V: HashStable<HCX>,
R: BuildHasher,
{
#[inline]
fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
stable_hash_reduce(hcx, hasher, self.iter(), self.len(), |hasher, hcx, (key, value)| {
let key = key.to_stable_hash_key(hcx);
key.hash_stable(hcx, hasher);
value.hash_stable(hcx, hasher);
});
}
}
// It is not safe to implement HashStable for HashSet or any other collection type
// with unstable but observable iteration order. // with unstable but observable iteration order.
// See https://github.com/rust-lang/compiler-team/issues/533 for further information. // See https://github.com/rust-lang/compiler-team/issues/533 for further information.
impl<V, HCX> !HashStable<HCX> for std::collections::HashSet<V> {} impl<V, HCX> !HashStable<HCX> for std::collections::HashSet<V> {}
impl<K, V, HCX> !HashStable<HCX> for std::collections::HashMap<K, V> {}
impl<K, V, HCX> HashStable<HCX> for ::std::collections::BTreeMap<K, V> impl<K, V, HCX> HashStable<HCX> for ::std::collections::BTreeMap<K, V>
where where
@ -730,35 +715,6 @@ fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
} }
} }
fn stable_hash_reduce<HCX, I, C, F>(
hcx: &mut HCX,
hasher: &mut StableHasher,
mut collection: C,
length: usize,
hash_function: F,
) where
C: Iterator<Item = I>,
F: Fn(&mut StableHasher, &mut HCX, I),
{
length.hash_stable(hcx, hasher);
match length {
1 => {
hash_function(hasher, hcx, collection.next().unwrap());
}
_ => {
let hash = collection
.map(|value| {
let mut hasher = StableHasher::new();
hash_function(&mut hasher, hcx, value);
hasher.finish::<Hash128>()
})
.reduce(|accum, value| accum.wrapping_add(value));
hash.hash_stable(hcx, hasher);
}
}
}
/// Controls what data we do or do not hash. /// Controls what data we do or do not hash.
/// Whenever a `HashStable` implementation caches its /// Whenever a `HashStable` implementation caches its
/// result, it needs to include `HashingControls` as part /// result, it needs to include `HashingControls` as part