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

pub trait Hash {
    fn hash<H: Hasher>(&self, state: &mut H);

    fn hash_slice<H: Hasher>(data: &[Self], state: &mut H)
    where
        Self: Sized
, { ... } }

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 !
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impl Hash for ()
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impl Hash for Ordering
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impl Hash for TypeId
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impl Hash for Error
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impl Hash for Pinned
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impl Hash for NonZeroU128
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impl Hash for NonZeroU16
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impl Hash for NonZeroU32
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impl Hash for NonZeroU64
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impl Hash for NonZeroU8
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impl Hash for NonZeroUsize
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impl Hash for RangeFull
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impl Hash for NoneError
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impl Hash for Duration
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impl Hash for bool
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impl Hash for char
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impl Hash for i8
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impl Hash for i16
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impl Hash for i32
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impl Hash for i64
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impl Hash for i128
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impl Hash for isize
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impl Hash for str
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impl Hash for u8
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impl Hash for u16
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impl Hash for u32
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impl Hash for u64
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impl Hash for u128
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impl Hash for usize
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impl<A> Hash for (A,) where
    A: Hash + ?Sized
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impl<A: Hash, B> Hash for (A, B) where
    B: Hash + ?Sized
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impl<A: Hash, B: Hash, C> Hash for (A, B, C) where
    C: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D> Hash for (A, B, C, D) where
    D: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E> Hash for (A, B, C, D, E) where
    E: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F> Hash for (A, B, C, D, E, F) where
    F: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G> Hash for (A, B, C, D, E, F, G) where
    G: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G: Hash, H> Hash for (A, B, C, D, E, F, G, H) where
    H: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G: Hash, H: Hash, I> Hash for (A, B, C, D, E, F, G, H, I) where
    I: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G: Hash, H: Hash, I: Hash, J> Hash for (A, B, C, D, E, F, G, H, I, J) where
    J: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G: Hash, H: Hash, I: Hash, J: Hash, K> Hash for (A, B, C, D, E, F, G, H, I, J, K) where
    K: Hash + ?Sized
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impl<A: Hash, B: Hash, C: Hash, D: Hash, E: Hash, F: Hash, G: Hash, H: Hash, I: Hash, J: Hash, K: Hash, L> Hash for (A, B, C, D, E, F, G, H, I, J, K, L) where
    L: Hash + ?Sized
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impl<Idx: Hash> Hash for Range<Idx>
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impl<Idx: Hash> Hash for RangeFrom<Idx>
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impl<Idx: Hash> Hash for RangeInclusive<Idx>
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impl<Idx: Hash> Hash for RangeTo<Idx>
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impl<Idx: Hash> Hash for RangeToInclusive<Idx>
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impl<P: Hash> Hash for Pin<P>
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impl<Ret> Hash for extern "C" fn() -> Ret
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impl<Ret> Hash for fn() -> Ret
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impl<Ret> Hash for unsafe extern "C" fn() -> Ret
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impl<Ret> Hash for unsafe fn() -> Ret
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impl<Ret, A> Hash for extern "C" fn(_: A) -> Ret
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impl<Ret, A> Hash for extern "C" fn(_: A, ...) -> Ret
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impl<Ret, A> Hash for fn(_: A) -> Ret
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impl<Ret, A> Hash for unsafe extern "C" fn(_: A) -> Ret
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impl<Ret, A> Hash for unsafe extern "C" fn(_: A, ...) -> Ret
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impl<Ret, A> Hash for unsafe fn(_: A) -> Ret
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impl<Ret, A, B> Hash for extern "C" fn(_: A, _: B) -> Ret
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impl<Ret, A, B> Hash for extern "C" fn(_: A, _: B, ...) -> Ret
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impl<Ret, A, B> Hash for fn(_: A, _: B) -> Ret
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impl<Ret, A, B> Hash for unsafe extern "C" fn(_: A, _: B) -> Ret
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impl<Ret, A, B> Hash for unsafe extern "C" fn(_: A, _: B, ...) -> Ret
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impl<Ret, A, B> Hash for unsafe fn(_: A, _: B) -> Ret
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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, C> Hash for extern "C" fn(_: A, _: B, _: C, ...) -> 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> Hash for unsafe extern "C" fn(_: A, _: B, _: C) -> 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<Ret, A, B, C> Hash for unsafe fn(_: A, _: B, _: C) -> 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<Ret, A, B, C, D> Hash for extern "C" fn(_: A, _: B, _: C, _: D, ...) -> Ret
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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 unsafe extern "C" fn(_: A, _: B, _: C, _: D) -> 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> Hash for unsafe fn(_: A, _: B, _: C, _: D) -> 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> Hash for extern "C" fn(_: A, _: B, _: C, _: D, _: E, ...) -> 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> Hash for unsafe extern "C" fn(_: A, _: B, _: C, _: D, _: E) -> 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, D, E> Hash for unsafe fn(_: A, _: B, _: C, _: D, _: E) -> 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<Ret, A, B, C, D, E, F> Hash for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, ...) -> Ret
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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<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<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 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 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 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 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<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<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<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<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> 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> Hash for unsafe 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> Hash for extern "C" fn(_: A, _: B, _: C, _: D, _: E, _: F, _: G, _: H, _: I) -> 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<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<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, 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, 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, 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, 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, F, G, H, I, J> Hash for 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> 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> 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, 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, 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, J, K> Hash for 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, 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, 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, I, J, K> Hash for unsafe 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, 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, 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, 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<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, 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, 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<T> Hash for Discriminant<T>
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impl<T: Hash + ?Sized> Hash for ManuallyDrop<T>
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impl<T: Hash> Hash for Bound<T>
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impl<T: Hash> Hash for Option<T>
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impl<T: Hash> Hash for Poll<T>
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impl<T: Hash> Hash for Reverse<T>
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impl<T: Hash> Hash for Wrapping<T>
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impl<T: Hash> Hash for [T; 0]
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impl<T: Hash> Hash for [T; 1]
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impl<T: Hash> Hash for [T; 2]
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impl<T: Hash> Hash for [T; 3]
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impl<T: Hash> Hash for [T; 4]
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impl<T: Hash> Hash for [T; 5]
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impl<T: Hash> Hash for [T; 6]
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impl<T: Hash> Hash for [T; 7]
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impl<T: Hash> Hash for [T; 8]
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impl<T: Hash> Hash for [T; 9]
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impl<T: Hash> Hash for [T; 10]
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impl<T: Hash> Hash for [T; 11]
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impl<T: Hash> Hash for [T; 12]
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impl<T: Hash> Hash for [T; 13]
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impl<T: Hash> Hash for [T; 14]
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impl<T: Hash> Hash for [T; 15]
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impl<T: Hash> Hash for [T; 16]
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impl<T: Hash> Hash for [T; 17]
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impl<T: Hash> Hash for [T; 18]
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impl<T: Hash> Hash for [T; 19]
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impl<T: Hash> Hash for [T; 20]
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impl<T: Hash> Hash for [T; 21]
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impl<T: Hash> Hash for [T; 22]
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impl<T: Hash> Hash for [T; 23]
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impl<T: Hash> Hash for [T; 24]
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impl<T: Hash> Hash for [T; 25]
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impl<T: Hash> Hash for [T; 26]
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impl<T: Hash> Hash for [T; 27]
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impl<T: Hash> Hash for [T; 28]
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impl<T: Hash> Hash for [T; 29]
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impl<T: Hash> Hash for [T; 30]
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impl<T: Hash> Hash for [T; 31]
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impl<T: Hash> Hash for [T; 32]
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impl<T: Hash> Hash for [T]
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impl<T: Hash, E: Hash> Hash for Result<T, E>
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impl<T: ?Sized + Hash, '_> Hash for &'_ T
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impl<T: ?Sized + Hash, '_> Hash for &'_ mut T
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impl<T: ?Sized> Hash for *const T
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impl<T: ?Sized> Hash for *mut T
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impl<T: ?Sized> Hash for PhantomData<T>
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impl<T: ?Sized> Hash for NonNull<T>
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impl<Y: Hash, R: Hash> Hash for GeneratorState<Y, R>
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