Trait std::cmp::Eq

pub trait Eq: PartialEq<Self> { }

Trait for equality comparisons which are equivalence relations.

This means, that in addition to a == b and a != b being strict inverses, the equality must be (for all a, b and c):

• reflexive: a == a;
• symmetric: a == b implies b == a; and
• transitive: a == b and b == c implies a == c.

This property cannot be checked by the compiler, and therefore Eq implies PartialEq, and has no extra methods.

Derivable

This trait can be used with #[derive]. When derived, because Eq has no extra methods, it is only informing the compiler that this is an equivalence relation rather than a partial equivalence relation. Note that the derive strategy requires all fields are Eq, which isn’t always desired.

How can I implement Eq?

If you cannot use the derive strategy, specify that your type implements Eq, which has no methods:

enum BookFormat { Paperback, Hardback, Ebook }
struct Book {
    isbn: i32,
    format: BookFormat,
}
impl PartialEq for Book {
    fn eq(&self, other: &Self) -> bool {
        self.isbn == other.isbn
    }
}
impl Eq for Book {}

Implementations on Foreign Types

impl<'a> Eq for Utf8LossyChunk<'a>

impl Eq for CpuidResult

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Implementors

impl Eq for BacktraceStatus

impl Eq for TryReserveError

impl Eq for Infallible

impl Eq for VarError

impl Eq for ErrorKind

impl Eq for SeekFrom

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for Shutdown

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for SearchStep

impl Eq for std::sync::atomic::Ordering

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

impl Eq for std::cmp::Ordering

impl Eq for bool

impl Eq for char

impl Eq for i8

impl Eq for i16

impl Eq for i32

impl Eq for i64

impl Eq for i128

impl Eq for isize

impl Eq for !

impl Eq for str

impl Eq for u8

impl Eq for u16

impl Eq for u32

impl Eq for u64

impl Eq for u128

impl Eq for ()

impl Eq for usize

impl Eq for AllocError

impl Eq for Layout

impl Eq for LayoutError

impl Eq for TypeId

impl Eq for CharTryFromError

impl Eq for DecodeUtf16Error

impl Eq for ParseCharError

impl Eq for CStr

impl Eq for CString

impl Eq for FromBytesWithNulError

impl Eq for FromVecWithNulError

impl Eq for IntoStringError

impl Eq for NulError

impl Eq for OsStr

impl Eq for OsString

impl Eq for Error

impl Eq for FileType

impl Eq for Permissions

impl Eq for PhantomPinned

impl Eq for AddrParseError

impl Eq for Ipv4Addr

impl Eq for Ipv6Addr

impl Eq for SocketAddrV4

impl Eq for SocketAddrV6

impl Eq for NonZeroI8

impl Eq for NonZeroI16

impl Eq for NonZeroI32

impl Eq for NonZeroI64

impl Eq for NonZeroI128

impl Eq for NonZeroIsize

impl Eq for NonZeroU8

impl Eq for NonZeroU16

impl Eq for NonZeroU32

impl Eq for NonZeroU64

impl Eq for NonZeroU128

impl Eq for NonZeroUsize

impl Eq for ParseFloatError

impl Eq for ParseIntError

impl Eq for TryFromIntError

impl Eq for RangeFull

impl Eq for NoneError

impl Eq for UCred

This is supported on Unix only.

impl Eq for Components<'_>

impl Eq for Path

impl Eq for PathBuf

impl Eq for StripPrefixError

impl Eq for ExitStatus

impl Eq for Output

impl Eq for ParseBoolError

impl Eq for Utf8Error

impl Eq for FromUtf8Error

impl Eq for String

impl Eq for RecvError

impl Eq for WaitTimeoutResult

impl Eq for AccessError

impl Eq for ThreadId

impl Eq for Duration

impl Eq for Instant

impl Eq for SystemTime

impl<'_, A> Eq for &'_ A where
    A: Eq + ?Sized, 

impl<'_, A> Eq for &'_ mut A where
    A: Eq + ?Sized, 

impl<'_, B> Eq for Cow<'_, B> where
    B: Eq + ToOwned + ?Sized, 

impl<'a> Eq for Component<'a>

impl<'a> Eq for Prefix<'a>

impl<'a> Eq for Location<'a>

impl<'a> Eq for PrefixComponent<'a>

impl<A> Eq for (A,) where
    A: Eq + ?Sized, 

impl<A> Eq for VecDeque<A> where
    A: Eq, 

impl<A, B> Eq for (A, B) where
    B: Eq + ?Sized,
    A: Eq, 

impl<A, B, C> Eq for (A, B, C) where
    C: Eq + ?Sized,
    B: Eq,
    A: Eq, 

impl<A, B, C, D> Eq for (A, B, C, D) where
    C: Eq,
    B: Eq,
    A: Eq,
    D: Eq + ?Sized, 

impl<A, B, C, D, E> Eq for (A, B, C, D, E) where
    C: Eq,
    E: Eq + ?Sized,
    B: Eq,
    A: Eq,
    D: Eq, 

impl<A, B, C, D, E, F> Eq for (A, B, C, D, E, F) where
    C: Eq,
    F: Eq + ?Sized,
    E: Eq,
    B: Eq,
    A: Eq,
    D: Eq, 

impl<A, B, C, D, E, F, G> Eq for (A, B, C, D, E, F, G) where
    C: Eq,
    F: Eq,
    E: Eq,
    B: Eq,
    A: Eq,
    G: Eq + ?Sized,
    D: Eq, 

impl<A, B, C, D, E, F, G, H> Eq for (A, B, C, D, E, F, G, H) where
    C: Eq,
    F: Eq,
    E: Eq,
    H: Eq + ?Sized,
    B: Eq,
    A: Eq,
    G: Eq,
    D: Eq, 

impl<A, B, C, D, E, F, G, H, I> Eq for (A, B, C, D, E, F, G, H, I) where
    C: Eq,
    F: Eq,
    I: Eq + ?Sized,
    E: Eq,
    H: Eq,
    B: Eq,
    A: Eq,
    G: Eq,
    D: Eq, 

impl<A, B, C, D, E, F, G, H, I, J> Eq for (A, B, C, D, E, F, G, H, I, J) where
    C: Eq,
    F: Eq,
    I: Eq,
    E: Eq,
    H: Eq,
    B: Eq,
    A: Eq,
    J: Eq + ?Sized,
    G: Eq,
    D: Eq, 

impl<A, B, C, D, E, F, G, H, I, J, K> Eq for (A, B, C, D, E, F, G, H, I, J, K) where
    C: Eq,
    F: Eq,
    K: Eq + ?Sized,
    I: Eq,
    E: Eq,
    H: Eq,
    B: Eq,
    A: Eq,
    J: Eq,
    G: Eq,
    D: Eq, 

impl<A, B, C, D, E, F, G, H, I, J, K, L> Eq for (A, B, C, D, E, F, G, H, I, J, K, L) where
    C: Eq,
    F: Eq,
    K: Eq,
    I: Eq,
    E: Eq,
    H: Eq,
    B: Eq,
    A: Eq,
    J: Eq,
    G: Eq,
    D: Eq,
    L: Eq + ?Sized, 

impl<Dyn> Eq for DynMetadata<Dyn> where
    Dyn: ?Sized, 

impl<H> Eq for BuildHasherDefault<H>

impl<Idx> Eq for Range<Idx> where
    Idx: Eq, 

impl<Idx> Eq for RangeFrom<Idx> where
    Idx: Eq, 

impl<Idx> Eq for RangeInclusive<Idx> where
    Idx: Eq, 

impl<Idx> Eq for RangeTo<Idx> where
    Idx: Eq, 

impl<Idx> Eq for RangeToInclusive<Idx> where
    Idx: Eq, 

impl<K, V> Eq for BTreeMap<K, V> where
    K: Eq,
    V: Eq, 

impl<K, V, S> Eq for HashMap<K, V, S> where
    K: Eq + Hash,
    V: Eq,
    S: BuildHasher, 

impl<P> Eq for Pin<P> where
    P: Deref,
    <P as Deref>::Target: Eq, 

impl<Ret> Eq for fn() -> Ret

impl<Ret> Eq for extern "C" fn() -> Ret

impl<Ret> Eq for unsafe fn() -> Ret

impl<Ret> Eq for unsafe extern "C" fn() -> Ret

impl<Ret, A> Eq for fn(A) -> Ret

impl<Ret, A> Eq for extern "C" fn(A) -> Ret

impl<Ret, A> Eq for extern "C" fn(A, ...) -> Ret

impl<Ret, A> Eq for unsafe fn(A) -> Ret

impl<Ret, A> Eq for unsafe extern "C" fn(A) -> Ret

impl<Ret, A> Eq for unsafe extern "C" fn(A, ...) -> Ret

impl<Ret, A, B> Eq for fn(A, B) -> Ret

impl<Ret, A, B> Eq for extern "C" fn(A, B) -> Ret

impl<Ret, A, B> Eq for extern "C" fn(A, B, ...) -> Ret

impl<Ret, A, B> Eq for unsafe fn(A, B) -> Ret

impl<Ret, A, B> Eq for unsafe extern "C" fn(A, B) -> Ret

impl<Ret, A, B> Eq for unsafe extern "C" fn(A, B, ...) -> Ret

impl<Ret, A, B, C> Eq for fn(A, B, C) -> Ret

impl<Ret, A, B, C> Eq for extern "C" fn(A, B, C) -> Ret

impl<Ret, A, B, C> Eq for extern "C" fn(A, B, C, ...) -> Ret

impl<Ret, A, B, C> Eq for unsafe fn(A, B, C) -> Ret

impl<Ret, A, B, C> Eq for unsafe extern "C" fn(A, B, C) -> Ret

impl<Ret, A, B, C> Eq for unsafe extern "C" fn(A, B, C, ...) -> Ret

impl<Ret, A, B, C, D> Eq for fn(A, B, C, D) -> Ret

impl<Ret, A, B, C, D> Eq for extern "C" fn(A, B, C, D) -> Ret

impl<Ret, A, B, C, D> Eq for extern "C" fn(A, B, C, D, ...) -> Ret

impl<Ret, A, B, C, D> Eq for unsafe fn(A, B, C, D) -> Ret

impl<Ret, A, B, C, D> Eq for unsafe extern "C" fn(A, B, C, D) -> Ret

impl<Ret, A, B, C, D> Eq for unsafe extern "C" fn(A, B, C, D, ...) -> Ret

impl<Ret, A, B, C, D, E> Eq for fn(A, B, C, D, E) -> Ret

impl<Ret, A, B, C, D, E> Eq for extern "C" fn(A, B, C, D, E) -> Ret

impl<Ret, A, B, C, D, E> Eq for extern "C" fn(A, B, C, D, E, ...) -> Ret

impl<Ret, A, B, C, D, E> Eq for unsafe fn(A, B, C, D, E) -> Ret

impl<Ret, A, B, C, D, E> Eq for unsafe extern "C" fn(A, B, C, D, E) -> Ret

impl<Ret, A, B, C, D, E> Eq for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for fn(A, B, C, D, E, F) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for extern "C" fn(A, B, C, D, E, F) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for extern "C" fn(A, B, C, D, E, F, ...) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for unsafe fn(A, B, C, D, E, F) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret

impl<Ret, A, B, C, D, E, F> Eq for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for fn(A, B, C, D, E, F, G) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for extern "C" fn(A, B, C, D, E, F, G) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for unsafe fn(A, B, C, D, E, F, G) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret

impl<Ret, A, B, C, D, E, F, G> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for fn(A, B, C, D, E, F, G, H) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for unsafe fn(A, B, C, D, E, F, G, H) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret

impl<Ret, A, B, C, D, E, F, G, H> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for fn(A, B, C, D, E, F, G, H, I) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for unsafe fn(A, B, C, D, E, F, G, H, I) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for fn(A, B, C, D, E, F, G, H, I, J) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret

impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Eq for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret

impl<T> Eq for Bound<T> where
    T: Eq, 

impl<T> Eq for Option<T> where
    T: Eq, 

impl<T> Eq for Poll<T> where
    T: Eq, 

impl<T> Eq for *const T where
    T: ?Sized, 

impl<T> Eq for *mut T where
    T: ?Sized, 

impl<T> Eq for [T] where
    T: Eq, 

impl<T> Eq for Cell<T> where
    T: Eq + Copy, 

impl<T> Eq for RefCell<T> where
    T: Eq + ?Sized, 

impl<T> Eq for BTreeSet<T> where
    T: Eq, 

impl<T> Eq for LinkedList<T> where
    T: Eq, 

impl<T> Eq for OnceCell<T> where
    T: Eq, 

impl<T> Eq for PhantomData<T> where
    T: ?Sized, 

impl<T> Eq for Discriminant<T>

impl<T> Eq for ManuallyDrop<T> where
    T: Eq + ?Sized, 

impl<T> Eq for Wrapping<T> where
    T: Eq, 

impl<T> Eq for NonNull<T> where
    T: ?Sized, 

impl<T> Eq for Rc<T> where
    T: Eq + ?Sized, 

impl<T> Eq for Arc<T> where
    T: Eq + ?Sized, 

impl<T> Eq for Reverse<T> where
    T: Eq, 

impl<T, A> Eq for Box<T, A> where
    T: Eq + ?Sized,
    A: Allocator, 

impl<T, A> Eq for Vec<T, A> where
    T: Eq,
    A: Allocator, 

impl<T, E> Eq for Result<T, E> where
    T: Eq,
    E: Eq, 

impl<T, S> Eq for HashSet<T, S> where
    T: Eq + Hash,
    S: BuildHasher, 

impl<T, const N: usize> Eq for [T; N] where
    T: Eq, 

impl<T: Eq> Eq for TrySendError<T>

impl<T: Eq> Eq for Cursor<T>

impl<T: Eq> Eq for SyncOnceCell<T>

impl<T: Eq> Eq for SendError<T>

impl<Y, R> Eq for GeneratorState<Y, R> where
    R: Eq,
    Y: Eq, 

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