Predicate in rustc_hir::attrs::diagnostic - Rust
Description: Predicate(s) in `#[rustc_on_unimplemented]`’s `on` filter. See `OnUnimplementedCondition`.

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## Predicate

# Enum Predicate

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    pub enum Predicate {
        Flag(Flag),
        Match(NameValue),
        Not(Box<Predicate>),
        All(ThinVec<Predicate>),
        Any(ThinVec<Predicate>),
    }

Expand description

Predicate(s) in `#[rustc_on_unimplemented]`’s `on` filter. See `OnUnimplementedCondition`.

It is similar to the predicate in the `cfg` attribute, and may contain nested predicates.

## Variants§

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### Flag(Flag)

A condition like `on(crate_local)`.

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### Match(NameValue)

A match, like `on(Rhs = "Whatever")`.

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### Not(Box<Predicate>)

Negation, like `on(not($pred))`.

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### All(ThinVec<Predicate>)

True if all predicates are true, like `on(all($a, $b, $c))`.

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### Any(ThinVec<Predicate>)

True if any predicate is true, like `on(any($a, $b, $c))`.

## Implementations§

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### impl Predicate

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#### pub fn eval(&self, eval: &mut impl FnMut(FlagOrNv<'_>) -> bool) -> bool

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#### pub fn visit_params(&self, span: Span, visit: &mut impl FnMut(Symbol, Span))

## Trait Implementations§

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### impl Clone for Predicate

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

Returns a duplicate 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 Predicate

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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 Predicate

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

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

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

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### impl<__CTX> HashStable<__CTX> for Predicate
where __CTX: HashStableContext,

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

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### impl PrintAttribute for Predicate

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#### fn should_render(&self) -> bool

Whether or not this will render as something meaningful, or if it’s skipped (which will force the containing struct to also skip printing a comma and the field name).
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#### fn print_attribute(&self, __p: &mut Printer)

## Auto Trait Implementations§

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### impl DynSend for Predicate

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### impl DynSync for Predicate

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### impl Freeze for Predicate

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### impl RefUnwindSafe for Predicate

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### impl Send for Predicate

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### impl Sync for Predicate

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### impl Unpin for Predicate

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### impl UnsafeUnpin for Predicate

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### impl UnwindSafe for Predicate

## 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> 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: Clone,

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#### unsafe fn clone_to_uninit(&self, dest: *mut u8)

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

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#### fn __clone_box(&self, _: Private) -> *mut ()

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

## 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: 16 bytes

Size for each variant:

- `Flag`: 1 byte
- `Match`: 16 bytes
- `Not`: 8 bytes
- `All`: 8 bytes
- `Any`: 8 bytes