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: &Book) -> bool {
        self.isbn == other.isbn
    }
}
impl Eq for Book {}

Implementations on Foreign Types

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

Implementors

• impl Eq for NonZeroU64

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

• impl Eq for LayoutErr

• impl Eq for Layout

• impl Eq for ParseIntError

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

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

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

• impl Eq for ()

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

• impl<T> Eq for [T; 28] where     T: Eq,

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

• impl Eq for i128

• impl Eq for AllocErr

• impl Eq for !

• impl<T> Eq for [T; 4] where     T: Eq,

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

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

• 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<T> Eq for Discriminant<T>

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

• impl Eq for NonZeroU8

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

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

• impl Eq for SearchStep

• impl<T> Eq for [T; 13] where     T: Eq,

• impl Eq for char

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

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

• impl<T> Eq for [T; 22] where     T: Eq,

• impl<T> Eq for [T; 12] where     T: Eq,

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

• impl<T> Eq for [T; 19] where     T: Eq,

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

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

• impl Eq for i8

• impl<T> Eq for [T; 20] where     T: Eq,

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

• impl<T> Eq for [T; 15] where     T: Eq,

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

• impl Eq for InvalidSequence

• impl<T> Eq for [T; 2] where     T: Eq,

• impl<T> Eq for [T; 25] where     T: Eq,

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

• impl<T> Eq for [T; 1] where     T: Eq,

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

• impl Eq for CharTryFromError

• 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<T> Eq for [T; 9] where     T: Eq,

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

• impl<T> Eq for [T; 29] where     T: Eq,

• 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<T> Eq for [T; 30] where     T: Eq,

• impl Eq for bool

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

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

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

• impl Eq for NoneError

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

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

• impl Eq for DecodeUtf16Error

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

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

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

• impl Eq for i32

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

• impl Eq for ParseBoolError

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

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

• impl<T> Eq for [T; 3] where     T: Eq,

• impl<T> Eq for [T; 6] where     T: Eq,

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

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

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

• impl Eq for isize

• impl<T> Eq for [T; 18] where     T: Eq,

• impl<T> Eq for [T; 8] where     T: Eq,

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

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

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

• impl<T> Eq for [T; 5] where     T: Eq,

• 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> Eq for unsafe fn(A, B, C, D, E) -> 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<T> Eq for RefCell<T> where     T: Eq + ?Sized,

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

• impl Eq for Utf8Error

• impl<Ret, A, B, C> Eq for extern "C" fn(A, B, C) -> 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 [T; 11] where     T: Eq,

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

• impl Eq for i16

• impl<T> Eq for ManuallyDrop<T> where     T: Eq,

• impl Eq for NonZeroU32

• 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 Eq for NonZeroU16

• impl Eq for str

• impl<T> Eq for [T; 16] where     T: Eq,

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

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

• impl<Ret, A> Eq for fn(A) -> Ret

• impl<T> Eq for [T; 23] where     T: Eq,

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

• impl<T> Eq for [T; 0] where     T: Eq,

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

• impl Eq for Duration

• impl<T> Eq for [T; 26] where     T: Eq,

• impl Eq for UnicodeVersion

• impl Eq for u128

• impl Eq for usize

• impl Eq for u8

• impl Eq for NonZeroU128

• 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<T> Eq for [T; 10] where     T: Eq,

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

• impl Eq for TypeId

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

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

• 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     A: Eq,     B: Eq,     C: Eq,     D: Eq,     E: Eq,     F: Eq,     G: Eq,     H: Eq,     I: Eq,     J: Eq,     K: Eq + ?Sized,

• impl<H> Eq for BuildHasherDefault<H>

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

• impl Eq for i64

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

• impl Eq for CannotReallocInPlace

• impl<T> Eq for [T; 32] where     T: Eq,

• impl<T> Eq for [T] where     T: Eq,

• impl Eq for u32

• impl<T> Eq for [T; 14] where     T: Eq,

• impl Eq for u16

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

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

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

• 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     A: Eq,     B: Eq,     C: Eq,     D: Eq,     E: Eq,     F: Eq,     G: Eq,     H: Eq,     I: Eq,     J: Eq,     K: Eq,     L: Eq + ?Sized,

• impl<T> Eq for [T; 7] where     T: Eq,

• impl Eq for FpCategory

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

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

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

• impl Eq for Error

• impl Eq for ParseFloatError

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

• impl Eq for RangeFull

• impl<T> Eq for [T; 17] where     T: Eq,

• impl Eq for ParseCharError

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

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

• impl<T> Eq for [T; 21] where     T: Eq,

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

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

• impl Eq for Ordering

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

• impl<T> Eq for [T; 24] where     T: Eq,

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

• impl<T> Eq for [T; 27] where     T: Eq,

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

• impl Eq for NonZeroUsize

• impl Eq for u64

• impl<T> Eq for [T; 31] where     T: Eq,

• impl<Ret> Eq for unsafe fn() -> Ret

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

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

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

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

• impl<T> Eq for Vec<T> where     T: Eq,

• impl Eq for CollectionAllocErr

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

• impl Eq for String

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

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

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

• impl Eq for ParseError

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

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

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

• impl Eq for ThreadId

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

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

• impl Eq for VarError

• impl Eq for CString

• impl Eq for NulError

• impl Eq for FromBytesWithNulError

• impl Eq for IntoStringError

• impl Eq for CStr

• impl Eq for OsString

• impl Eq for OsStr

• impl Eq for Permissions

• impl Eq for FileType

• impl Eq for ErrorKind

• impl Eq for SeekFrom

• impl Eq for IpAddr

• impl Eq for Ipv6MulticastScope

• impl Eq for Ipv4Addr

• impl Eq for Ipv6Addr

• impl Eq for SocketAddr

• impl Eq for SocketAddrV4

• impl Eq for SocketAddrV6

• impl Eq for AddrParseError

• impl Eq for Shutdown

• impl<'a> Eq for Prefix<'a>

• impl<'a> Eq for PrefixComponent<'a>

• impl<'a> Eq for Component<'a>

• impl<'a> Eq for Components<'a>

• impl Eq for PathBuf

• impl Eq for StripPrefixError

• impl Eq for Path

• impl Eq for Output

• impl Eq for ExitStatus

• impl<T: Eq> Eq for SendError<T>

• impl Eq for RecvError

• impl Eq for TryRecvError

• impl Eq for RecvTimeoutError

• impl<T: Eq> Eq for TrySendError<T>

• impl Eq for WaitTimeoutResult

• impl Eq for Instant

• impl Eq for SystemTime