PhantomCovariant in core::marker - Rust (original) (raw)

Struct PhantomCovariant

pub struct PhantomCovariant<T>(/* private fields */)
where
    T: ?Sized;

🔬This is a nightly-only experimental API. (phantom_variance_markers #135806)

Expand description

Zero-sized type used to mark a type parameter as covariant.

Types used as part of the return value from a function are covariant. If the type is _also_passed as a parameter then it is invariant. See the reference for more information.

§Layout

For all T, the following are guaranteed:

size_of::<PhantomCovariant<T>>() == 0
align_of::<PhantomCovariant<T>>() == 1

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Source

🔬This is a nightly-only experimental API. (phantom_variance_markers #135806)

Constructs a new instance of the variance marker.

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Tests for self and other values to be equal, and is used by ==.

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Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

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This method returns an ordering between self and other values if one exists. Read more

1.0.0 · Source §

Tests less than (for self and other) and is used by the < operator. Read more

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Tests less than or equal to (for self and other) and is used by the<= operator. Read more

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Tests greater than (for self and other) and is used by the >operator. Read more

1.0.0 · Source §

Tests greater than or equal to (for self and other) and is used by the >= operator. Read more

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