pub(crate) enum ImplTraitContext {
    Universal,
    ReturnPositionOpaqueTy {
        origin: OpaqueTyOrigin,
        fn_kind: FnDeclKind,
    },
    TypeAliasesOpaqueTy {
        in_assoc_ty: bool,
    },
    FeatureGated(ImplTraitPosition, Symbol),
    Disallowed(ImplTraitPosition),
}
Expand description

Context of impl Trait in code, which determines whether it is allowed in an HIR subtree, and if so, what meaning it has.

Variants§

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Universal

Treat impl Trait as shorthand for a new universal generic parameter. Example: fn foo(x: impl Debug), where impl Debug is conceptually equivalent to a fresh universal parameter like fn foo<T: Debug>(x: T).

Newly generated parameters should be inserted into the given Vec.

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ReturnPositionOpaqueTy

Fields

§origin: OpaqueTyOrigin

Origin: Either OpaqueTyOrigin::FnReturn or OpaqueTyOrigin::AsyncFn,

§fn_kind: FnDeclKind

Treat impl Trait as shorthand for a new opaque type. Example: fn foo() -> impl Debug, where impl Debug is conceptually equivalent to a new opaque type like type T = impl Debug; fn foo() -> T.

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TypeAliasesOpaqueTy

Fields

§in_assoc_ty: bool

Impl trait in type aliases.

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FeatureGated(ImplTraitPosition, Symbol)

impl Trait is unstably accepted in this position.

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Disallowed(ImplTraitPosition)

impl Trait is not accepted in this position.

Trait Implementations§

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impl Clone for ImplTraitContext

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fn clone(&self) -> ImplTraitContext

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for ImplTraitContext

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl PartialEq<ImplTraitContext> for ImplTraitContext

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fn eq(&self, other: &ImplTraitContext) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Copy for ImplTraitContext

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impl Eq for ImplTraitContext

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impl StructuralEq for ImplTraitContext

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impl StructuralPartialEq for ImplTraitContext

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 12 bytes

Size for each variant:

  • Universal: 0 bytes
  • ReturnPositionOpaqueTy: 11 bytes
  • TypeAliasesOpaqueTy: 1 byte
  • FeatureGated: 7 bytes
  • Disallowed: 1 byte