# Enum rustc_type_ir::canonical::CanonicalVarKind

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    pub enum CanonicalVarKind<I: Interner> {
        Ty(CanonicalTyVarKind),
        PlaceholderTy(I::PlaceholderTy),
        Region(UniverseIndex),
        PlaceholderRegion(I::PlaceholderRegion),
        Const(UniverseIndex, I::Ty),
        Effect,
        PlaceholderConst(I::PlaceholderConst, I::Ty),
    }

Expand description

Describes the “kind” of the canonical variable. This is a “kind” in the type-theory sense of the term – i.e., a “meta” type system that analyzes type-like values.

## Variants§

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### Ty(CanonicalTyVarKind)

Some kind of type inference variable.

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### PlaceholderTy(I::PlaceholderTy)

A “placeholder” that represents “any type”.

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### Region(UniverseIndex)

Region variable `'?R`.

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### PlaceholderRegion(I::PlaceholderRegion)

A “placeholder” that represents “any region”. Created when you are solving a goal like `for<'a> T: Foo<'a>` to represent the bound region `'a`.

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### Const(UniverseIndex, I::Ty)

Some kind of const inference variable.

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### Effect

Effect variable `'?E`.

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### PlaceholderConst(I::PlaceholderConst, I::Ty)

A “placeholder” that represents “any const”.

## Implementations§

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### impl<I: Interner> CanonicalVarKind<I>

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#### pub fn universe(self) -> UniverseIndex

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#### pub fn with_updated_universe(self, ui: UniverseIndex) -> CanonicalVarKind<I>

Replaces the universe of this canonical variable with `ui`.

In case this is a float or int variable, this causes an ICE if the updated universe is not the root.

## Trait Implementations§

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### impl<I: Interner> Clone for CanonicalVarKind<I>

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#### fn clone(&self) -> Self

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<I: Interner> Debug for CanonicalVarKind<I>

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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<I: Interner, __D: TyDecoder<I = I>> Decodable<__D> for CanonicalVarKind<I>
where I::PlaceholderTy: Decodable<__D>, I::PlaceholderRegion: Decodable<__D>, I::Ty: Decodable<__D>, I::PlaceholderConst: Decodable<__D>,

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#### fn decode(__decoder: &mut __D) -> Self

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### impl<I: Interner, __E: TyEncoder<I = I>> Encodable<__E> for CanonicalVarKind<I>
where I::PlaceholderTy: Encodable<__E>, I::PlaceholderRegion: Encodable<__E>, I::Ty: Encodable<__E>, I::PlaceholderConst: Encodable<__E>,

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#### fn encode(&self, __encoder: &mut __E)

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### impl<I: Interner> Hash for CanonicalVarKind<I>

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#### fn hash<__HI>(&self, __state: &mut __HI)
where __HI: Hasher,

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl<I: Interner, __CTX> HashStable<__CTX> for CanonicalVarKind<I>
where I::PlaceholderTy: HashStable<__CTX>, I::PlaceholderRegion: HashStable<__CTX>, I::Ty: HashStable<__CTX>, I::PlaceholderConst: HashStable<__CTX>,

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#### fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)

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### impl<I: Interner> PartialEq for CanonicalVarKind<I>

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#### fn eq(&self, other: &Self) -> 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<I: Interner> TypeFoldable<I> for CanonicalVarKind<I>
where I::Ty: TypeFoldable<I>,

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#### fn try_fold_with<F: FallibleTypeFolder<I>>( self, folder: &mut F ) -> Result<Self, F::Error>

The entry point for folding. To fold a value `t` with a folder `f` call: `t.try_fold_with(f)`. Read more
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#### fn fold_with<F: TypeFolder<I>>(self, folder: &mut F) -> Self

A convenient alternative to `try_fold_with` for use with infallible folders. Do not override this method, to ensure coherence with `try_fold_with`.
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### impl<I: Interner> TypeVisitable<I> for CanonicalVarKind<I>
where I::Ty: TypeVisitable<I>,

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#### fn visit_with<V: TypeVisitor<I>>( &self, visitor: &mut V ) -> ControlFlow<V::BreakTy>

The entry point for visiting. To visit a value `t` with a visitor `v` call: `t.visit_with(v)`. Read more
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### impl<I: Interner> Copy for CanonicalVarKind<I>

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### impl<I: Interner> Eq for CanonicalVarKind<I>

## Auto Trait Implementations§

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### impl<I> RefUnwindSafe for CanonicalVarKind<I>
where <I as Interner>::PlaceholderConst: RefUnwindSafe, <I as Interner>::PlaceholderRegion: RefUnwindSafe, <I as Interner>::PlaceholderTy: RefUnwindSafe, <I as Interner>::Ty: RefUnwindSafe,

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### impl<I> Send for CanonicalVarKind<I>
where <I as Interner>::PlaceholderConst: Send, <I as Interner>::PlaceholderRegion: Send, <I as Interner>::PlaceholderTy: Send, <I as Interner>::Ty: Send,

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### impl<I> Sync for CanonicalVarKind<I>
where <I as Interner>::PlaceholderConst: Sync, <I as Interner>::PlaceholderRegion: Sync, <I as Interner>::PlaceholderTy: Sync, <I as Interner>::Ty: Sync,

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### impl<I> Unpin for CanonicalVarKind<I>
where <I as Interner>::PlaceholderConst: Unpin, <I as Interner>::PlaceholderRegion: Unpin, <I as Interner>::PlaceholderTy: Unpin, <I as Interner>::Ty: Unpin,

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### impl<I> UnwindSafe for CanonicalVarKind<I>
where <I as Interner>::PlaceholderConst: UnwindSafe, <I as Interner>::PlaceholderRegion: UnwindSafe, <I as Interner>::PlaceholderTy: UnwindSafe, <I as Interner>::Ty: UnwindSafe,

## Blanket Implementations§

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### impl<T> Any for T
where 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 T
where 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 T
where 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, R> CollectAndApply<T, R> for T

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#### fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to `f(&iter.collect::<Vec<_>>())`.

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#### type Output = R

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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 T
where 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 T
where 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 T
where 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 T
where 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: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.