# Enum rustc_lint_defs::LintExpectationId

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    pub enum LintExpectationId {
        Unstable {
            attr_id: AttrId,
            lint_index: Option<u16>,
        },
        Stable {
            hir_id: HirId,
            attr_index: u16,
            lint_index: Option<u16>,
            attr_id: Option<AttrId>,
        },
    }

Expand description

Each lint expectation has a `LintExpectationId` assigned by the `LintLevelsBuilder`. Expected diagnostics get the lint level `Expect` which stores the `LintExpectationId` to match it with the actual expectation later on.

The `LintExpectationId` has to be stable between compilations, as diagnostic instances might be loaded from cache. Lint messages can be emitted during an `EarlyLintPass` operating on the AST and during a `LateLintPass` traversing the HIR tree. The AST doesn’t have enough information to create a stable id. The `LintExpectationId` will instead store the `AttrId` defining the expectation. These `LintExpectationId` will be updated to use the stable [`HirId`] once the AST has been lowered. The transformation is done by the `LintLevelsBuilder`

Each lint inside the `expect` attribute is tracked individually, the `lint_index` identifies the lint inside the attribute and ensures that the IDs are unique.

The index values have a type of `u16` to reduce the size of the `LintExpectationId`. It’s reasonable to assume that no user will define 2^16 attributes on one node or have that amount of lints listed. `u16` values should therefore suffice.

## Variants§

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### Unstable

Used for lints emitted during the `EarlyLintPass`. This id is not hash stable and should not be cached.

#### Fields

§`attr_id: AttrId`
§`lint_index: Option<u16>`
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### Stable

The [`HirId`] that the lint expectation is attached to. This id is stable and can be cached. The additional index ensures that nodes with several expectations can correctly match diagnostics to the individual expectation.

#### Fields

§`hir_id: HirId`
§`attr_index: u16`
§`lint_index: Option<u16>`
§`attr_id: Option<AttrId>`

## Implementations§

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### impl LintExpectationId

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#### pub fn is_stable(&self) -> bool

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#### pub fn get_lint_index(&self) -> Option<u16>

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#### pub fn set_lint_index(&mut self, new_lint_index: Option<u16>)

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#### pub fn normalize(self) -> Self

Prepares the id for hashing. Removes references to the ast. Should only be called when the id is stable.

## Trait Implementations§

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### impl Clone for LintExpectationId

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

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 LintExpectationId

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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<__D: SpanDecoder> Decodable<__D> for LintExpectationId

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

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### impl<__E: SpanEncoder> Encodable<__E> for LintExpectationId

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

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### impl Hash for LintExpectationId

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#### fn hash<__H: Hasher>(&self, state: &mut __H)

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<HCX: HashStableContext> HashStable<HCX> for LintExpectationId

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#### fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher)

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### impl Ord for LintExpectationId

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#### fn cmp(&self, other: &LintExpectationId) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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#### fn max(self, other: Self) -> Self
where Self: Sized,

Compares and returns the maximum of two values. Read more
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#### fn min(self, other: Self) -> Self
where Self: Sized,

Compares and returns the minimum of two values. Read more
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#### fn clamp(self, min: Self, max: Self) -> Self
where Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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### impl PartialEq for LintExpectationId

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#### fn eq(&self, other: &LintExpectationId) -> 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 PartialOrd for LintExpectationId

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#### fn partial_cmp(&self, other: &LintExpectationId) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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### impl<HCX: HashStableContext> ToStableHashKey<HCX> for LintExpectationId

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#### type KeyType = (HirId, u16, u16)

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#### fn to_stable_hash_key(&self, _: &HCX) -> Self::KeyType

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### impl Copy for LintExpectationId

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### impl Eq for LintExpectationId

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### impl StructuralPartialEq for LintExpectationId

## Auto Trait Implementations§

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### impl DynSend for LintExpectationId

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### impl DynSync for LintExpectationId

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### impl Freeze for LintExpectationId

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### impl RefUnwindSafe for LintExpectationId

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### impl Send for LintExpectationId

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### impl Sync for LintExpectationId

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### impl Unpin for LintExpectationId

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### impl UnwindSafe for LintExpectationId

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = _

Alignment of `Self`.
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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> AnyEq for T
where T: Any + PartialEq,

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#### fn equals(&self, other: &(dyn Any + 'static)) -> bool

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#### fn as_any(&self) -> &(dyn Any + 'static)

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### impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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#### fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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#### fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T>, ) -> &'a mut [T]

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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> CloneToUninit for T
where T: Copy,

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#### unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dst`. Read more
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### impl<T> CloneToUninit for T
where T: Clone,

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#### default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dst`. Read more
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### impl<Q, K> Comparable<K> for Q
where Q: Ord + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn compare(&self, key: &K) -> Ordering

Compare self to `key` and return their ordering.
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Compare self to `key` and return `true` if they are equal.
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### impl<T> Filterable for T

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#### fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. 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> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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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> IntoEither for T

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#### fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left` is `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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#### fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left(&self)` returns `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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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.
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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<T> ErasedDestructor for T
where T: 'static,

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### impl<T> MaybeSendSync for T
where T: Send + Sync,

## 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: 20 bytes

Size for each variant:

- `Unstable`: 10 bytes
- `Stable`: 18 bytes