Trait wasmtime_environ::__core::cmp::Eq

1.0.0 · source ·

pub trait Eq: PartialEq { }

Expand description

Trait for comparisons corresponding to equivalence relations.

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

reflexive: a == a;
symmetric: a == b implies b == a (required by PartialEq as well); and
transitive: a == b and b == c implies a == c (required by PartialEq as well).

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

Violating this property is a logic error. The behavior resulting from a logic error is not specified, but users of the trait must ensure that such logic errors do not result in undefined behavior. This means that unsafe code must not rely on the correctness of these methods.

Implement Eq in addition to PartialEq if it’s guaranteed that PartialEq::eq(a, a) always returns true (reflexivity), in addition to the symmetric and transitive properties already required by PartialEq.

§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 {}

Object Safety§

This trait is not object safe.

Trait wasmtime_environ::__core::cmp::EqCopy item path

§Derivable

§How can I implement Eq?

Object Safety§

Implementors§

impl Eq for hashbrown::TryReserveError

impl Eq for log::Level

impl Eq for LevelFilter

impl Eq for CDataModel

impl Eq for Size

impl Eq for target_lexicon::parse_error::ParseError

impl Eq for Aarch64Architecture

impl Eq for target_lexicon::targets::Architecture

impl Eq for ArmArchitecture

impl Eq for target_lexicon::targets::BinaryFormat

impl Eq for CustomVendor

impl Eq for Environment

impl Eq for Mips32Architecture

impl Eq for Mips64Architecture

impl Eq for OperatingSystem

impl Eq for Riscv32Architecture

impl Eq for Riscv64Architecture

impl Eq for Vendor

impl Eq for X86_32Architecture

impl Eq for CallingConvention

impl Eq for target_lexicon::triple::Endianness

impl Eq for PointerWidth

impl Eq for BidiClass

impl Eq for IsNormalized

impl Eq for Origin

impl Eq for url::parser::ParseError

impl Eq for SyntaxViolation

impl Eq for EntityIndex

impl Eq for FlagValue

impl Eq for GlobalInit

impl Eq for Trap

impl Eq for WasmType

impl Eq for BlockType

impl Eq for CanonicalOption

impl Eq for ComponentExternalKind

impl Eq for ComponentOuterAliasKind

impl Eq for ComponentTypeRef

impl Eq for ComponentValType

impl Eq for wasmtime_environ::wasmparser::Encoding

impl Eq for ExternalKind

impl Eq for FrameKind

impl Eq for HeapType

impl Eq for InstantiationArgKind

impl Eq for OuterAliasKind

impl Eq for PrimitiveValType

impl Eq for TypeBounds

impl Eq for ValType

impl Eq for AsciiChar

impl Eq for Infallible

impl Eq for wasmtime_environ::__core::fmt::Alignment

impl Eq for IpAddr

impl Eq for Ipv6MulticastScope

impl Eq for SocketAddr

impl Eq for FpCategory

impl Eq for IntErrorKind

impl Eq for SearchStep

impl Eq for wasmtime_environ::__core::sync::atomic::Ordering

impl Eq for wasmtime_environ::__core::cmp::Ordering

impl Eq for TryReserveErrorKind

impl Eq for BacktraceStatus

impl Eq for VarError

impl Eq for SeekFrom

impl Eq for ErrorKind

impl Eq for Shutdown

impl Eq for BacktraceStyle

impl Eq for RecvTimeoutError

impl Eq for TryRecvError

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

Trait wasmtime_environ::__core::cmp::Eq

§How can I implement `Eq`?