1.0.0[][src]Trait std::hash::Hash

pub trait Hash {
    fn hash<H>(&self, state: &mut H)
    where
        H: Hasher
; fn hash_slice<H>(data: &[Self], state: &mut H)
    where
        H: Hasher
, { ... } }

A hashable type.

Types implementing Hash are able to be hashed with an instance of Hasher.

Implementing Hash

You can derive Hash with #[derive(Hash)] if all fields implement Hash. The resulting hash will be the combination of the values from calling hash on each field.

#[derive(Hash)]
struct Rustacean {
    name: String,
    country: String,
}Run

If you need more control over how a value is hashed, you can of course implement the Hash trait yourself:

use std::hash::{Hash, Hasher};

struct Person {
    id: u32,
    name: String,
    phone: u64,
}

impl Hash for Person {
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.id.hash(state);
        self.phone.hash(state);
    }
}Run

Hash and Eq

When implementing both Hash and Eq, it is important that the following property holds:

k1 == k2 -> hash(k1) == hash(k2)

In other words, if two keys are equal, their hashes must also be equal. HashMap and HashSet both rely on this behavior.

Thankfully, you won't need to worry about upholding this property when deriving both Eq and Hash with #[derive(PartialEq, Eq, Hash)].

Required Methods

Feeds this value into the given Hasher.

Examples

use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};

let mut hasher = DefaultHasher::new();
7920.hash(&mut hasher);
println!("Hash is {:x}!", hasher.finish());Run

Provided Methods

Feeds a slice of this type into the given Hasher.

Examples

use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};

let mut hasher = DefaultHasher::new();
let numbers = [6, 28, 496, 8128];
Hash::hash_slice(&numbers, &mut hasher);
println!("Hash is {:x}!", hasher.finish());Run

Implementors

impl Hash for Error
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impl<T> Hash for [T; 7] where
    T: Hash
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret
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impl<Ret> Hash for fn() -> Ret
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impl Hash for u64
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impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret
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impl Hash for ()
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impl<'a, T> Hash for &'a T where
    T: Hash + ?Sized
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impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C, ...) -> Ret
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impl<Ret, A, B> Hash for fn(A, B) -> Ret
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impl Hash for bool
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe fn(A, B, C, D, E) -> Ret
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impl<T> Hash for [T; 10] where
    T: Hash
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impl<T> Hash for [T; 6] where
    T: Hash
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impl<T> Hash for [T; 8] where
    T: Hash
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret
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impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe fn(A, B, C, D, E, F, G, H, I) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E> Hash for fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
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impl<Ret, A> Hash for unsafe fn(A) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for fn(A, B, C, D, E, F, G) -> Ret
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impl<T> Hash for [T; 17] where
    T: Hash
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impl<Ret, A> Hash for unsafe extern "C" fn(A, ...) -> Ret
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impl<T> Hash for [T; 24] where
    T: Hash
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impl<T> Hash for ManuallyDrop<T> where
    T: Hash + ?Sized
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impl<T> Hash for Wrapping<T> where
    T: Hash
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impl<Ret, A, B, C, D, E, F> Hash for fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret
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impl Hash for u16
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impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
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impl Hash for NonZeroU32
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impl Hash for Pinned
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impl<T> Hash for [T; 16] where
    T: Hash
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impl<Idx> Hash for RangeToInclusive<Idx> where
    Idx: Hash
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impl<A, B, C, D, E> Hash for (A, B, C, D, E) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash + ?Sized
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impl Hash for NonZeroU8
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impl<T> Hash for [T; 26] where
    T: Hash
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impl<T> Hash for [T; 25] where
    T: Hash
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impl<T> Hash for Reverse<T> where
    T: Hash
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impl Hash for i64
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impl Hash for NonZeroU16
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impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for fn(A, B, C, D, E, F, G, H, I, J) -> Ret
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impl<T> Hash for Poll<T> where
    T: Hash
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impl<T> Hash for Bound<T> where
    T: Hash
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impl<T> Hash for [T; 15] where
    T: Hash
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impl<T> Hash for [T; 32] where
    T: Hash
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impl<Ret, A, B, C, D> Hash for unsafe fn(A, B, C, D) -> Ret
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impl Hash for RangeFull
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impl Hash for usize
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impl Hash for NonZeroU64
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impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B, ...) -> Ret
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impl<'a, T> Hash for &'a mut T where
    T: Hash + ?Sized
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret
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impl Hash for Ordering
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impl<Ret> Hash for unsafe extern "C" fn() -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F, ...) -> Ret
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impl<T> Hash for [T; 31] where
    T: Hash
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impl<Idx> Hash for RangeTo<Idx> where
    Idx: Hash
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impl<T, E> Hash for Result<T, E> where
    E: Hash,
    T: Hash
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impl<A, B, C> Hash for (A, B, C) where
    A: Hash,
    B: Hash,
    C: Hash + ?Sized
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impl<A, B, C, D> Hash for (A, B, C, D) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash + ?Sized
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impl<Ret, A, B> Hash for extern "C" fn(A, B, ...) -> Ret
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impl<A, B, C, D, E, F, G, H, I, J, K> Hash for (A, B, C, D, E, F, G, H, I, J, K) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash,
    H: Hash,
    I: Hash,
    J: Hash,
    K: Hash + ?Sized
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impl Hash for u128
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret
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impl<T> Hash for *mut T where
    T: ?Sized
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impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C, ...) -> Ret
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impl<T> Hash for Discriminant<T>
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impl<T> Hash for [T; 21] where
    T: Hash
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
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impl<T> Hash for [T; 3] where
    T: Hash
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impl Hash for char
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impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
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impl<T> Hash for [T; 27] where
    T: Hash
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impl<T> Hash for [T; 28] where
    T: Hash
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impl<T> Hash for [T; 1] where
    T: Hash
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impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F) -> Ret
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impl Hash for i32
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impl<A> Hash for (A,) where
    A: Hash + ?Sized
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impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B) -> Ret
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impl<A, B> Hash for (A, B) where
    A: Hash,
    B: Hash + ?Sized
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impl Hash for Duration
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impl<Ret, A, B> Hash for extern "C" fn(A, B) -> Ret
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impl<Ret, A, B, C> Hash for fn(A, B, C) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret
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impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for fn(A, B, C, D, E, F, G, H) -> Ret
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impl<T> Hash for [T] where
    T: Hash
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impl<T> Hash for PhantomData<T> where
    T: ?Sized
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for fn(A, B, C, D, E, F, G, H, I) -> Ret
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impl<T> Hash for *const T where
    T: ?Sized
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impl<Y, R> Hash for GeneratorState<Y, R> where
    R: Hash,
    Y: Hash
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impl<T> Hash for [T; 5] where
    T: Hash
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impl<A, B, C, D, E, F, G, H> Hash for (A, B, C, D, E, F, G, H) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash,
    H: Hash + ?Sized
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
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impl<T> Hash for [T; 9] where
    T: Hash
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impl<Ret, A> Hash for fn(A) -> Ret
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impl Hash for TypeId
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impl<T> Hash for [T; 19] where
    T: Hash
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impl<T> Hash for [T; 0] where
    T: Hash
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impl<T> Hash for [T; 12] where
    T: Hash
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impl<A, B, C, D, E, F, G, H, I, J> Hash for (A, B, C, D, E, F, G, H, I, J) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash,
    H: Hash,
    I: Hash,
    J: Hash + ?Sized
[src]

impl<Idx> Hash for RangeInclusive<Idx> where
    Idx: Hash
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
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impl Hash for !
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impl<Ret> Hash for extern "C" fn() -> Ret
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impl Hash for isize
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impl<T> Hash for [T; 13] where
    T: Hash
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impl<Idx> Hash for RangeFrom<Idx> where
    Idx: Hash
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impl Hash for u32
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impl<T> Hash for [T; 20] where
    T: Hash
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impl<T> Hash for [T; 29] where
    T: Hash
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret
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impl<T> Hash for Option<T> where
    T: Hash
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impl Hash for i16
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impl Hash for i8
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impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D) -> Ret
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impl<T> Hash for [T; 23] where
    T: Hash
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impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for unsafe fn(A, B, C, D, E, F) -> Ret
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impl<T> Hash for [T; 4] where
    T: Hash
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impl<Ret, A, B, C, D> Hash for fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D, ...) -> Ret
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impl Hash for NonZeroUsize
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impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C) -> Ret
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impl<A, B, C, D, E, F, G, H, I, J, K, L> Hash for (A, B, C, D, E, F, G, H, I, J, K, L) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash,
    H: Hash,
    I: Hash,
    J: Hash,
    K: Hash,
    L: Hash + ?Sized
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impl<T> Hash for [T; 11] where
    T: Hash
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impl Hash for str
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impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe fn(A, B, C, D, E, F, G) -> Ret
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impl<T> Hash for [T; 14] where
    T: Hash
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret
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impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe fn(A, B, C, D, E, F, G, H) -> Ret
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impl Hash for NonZeroU128
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impl<Ret> Hash for unsafe fn() -> Ret
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impl<T> Hash for NonNull<T> where
    T: ?Sized
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret
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impl<Ret, A> Hash for extern "C" fn(A) -> Ret
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impl<Ret, A, B, C> Hash for unsafe fn(A, B, C) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C) -> Ret
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impl Hash for NoneError
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impl<T> Hash for [T; 22] where
    T: Hash
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impl<A, B, C, D, E, F, G> Hash for (A, B, C, D, E, F, G) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash + ?Sized
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
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impl<T> Hash for [T; 18] where
    T: Hash
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impl Hash for u8
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impl<A, B, C, D, E, F> Hash for (A, B, C, D, E, F) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash + ?Sized
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impl<Ret, A> Hash for unsafe extern "C" fn(A) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret
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impl<T> Hash for [T; 30] where
    T: Hash
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impl<Ret, A> Hash for extern "C" fn(A, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret
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impl<Idx> Hash for Range<Idx> where
    Idx: Hash
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impl<T> Hash for [T; 2] where
    T: Hash
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impl<A, B, C, D, E, F, G, H, I> Hash for (A, B, C, D, E, F, G, H, I) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash,
    E: Hash,
    F: Hash,
    G: Hash,
    H: Hash,
    I: Hash + ?Sized
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impl<Ret, A, B> Hash for unsafe fn(A, B) -> Ret
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impl Hash for i128
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impl<T> Hash for LinkedList<T> where
    T: Hash
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impl Hash for String
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impl<A> Hash for VecDeque<A> where
    A: Hash
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impl<K, V> Hash for BTreeMap<K, V> where
    K: Hash,
    V: Hash
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impl<T> Hash for Vec<T> where
    T: Hash
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impl<T> Hash for BTreeSet<T> where
    T: Hash
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impl<T> Hash for Box<T> where
    T: Hash + ?Sized
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impl<'a, B> Hash for Cow<'a, B> where
    B: Hash + ToOwned + ?Sized
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impl<T> Hash for Arc<T> where
    T: Hash + ?Sized
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impl<T> Hash for Rc<T> where
    T: Hash + ?Sized
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impl Hash for ThreadId
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impl Hash for CString
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impl Hash for CStr
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impl Hash for OsString
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impl Hash for OsStr
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impl Hash for FileType
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impl Hash for ErrorKind
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impl Hash for IpAddr
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impl Hash for Ipv6MulticastScope
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impl Hash for Ipv4Addr
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impl Hash for Ipv6Addr
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impl Hash for SocketAddr
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impl Hash for SocketAddrV4
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impl Hash for SocketAddrV6
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impl<'a> Hash for Prefix<'a>
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impl<'a> Hash for PrefixComponent<'a>
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impl<'a> Hash for Component<'a>
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impl Hash for PathBuf
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impl Hash for Path
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impl Hash for Instant
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impl Hash for SystemTime
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