# Struct rustc_middle::ty::Predicate

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    pub struct Predicate<'tcx>(pub(super) Interned<'tcx, WithCachedTypeInfo<Binder<'tcx, PredicateKind<'tcx>>>>);

Expand description

A statement that can be proven by a trait solver. This includes things that may show up in where clauses, such as trait predicates and projection predicates, and also things that are emitted as part of type checking such as `ObjectSafe` predicate which is emitted when a type is coerced to a trait object.

Use this rather than `PredicateKind`, whenever possible.

## Tuple Fields§

§`0: Interned<'tcx, WithCachedTypeInfo<Binder<'tcx, PredicateKind<'tcx>>>>`

## Implementations§

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### impl<'tcx> Predicate<'tcx>

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#### pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>>

Gets the inner `ty::Binder<'tcx, PredicateKind<'tcx>>`.

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#### pub fn flags(self) -> TypeFlags

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#### pub fn outer_exclusive_binder(self) -> DebruijnIndex

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#### pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>>

Flips the polarity of a Predicate.

Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.

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#### pub fn is_coinductive(self, tcx: TyCtxt<'tcx>) -> bool

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#### pub fn allow_normalization(self) -> bool

Whether this projection can be soundly normalized.

Wf predicates must not be normalized, as normalization can remove required bounds which would cause us to unsoundly accept some programs. See #91068.

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### impl<'tcx> Predicate<'tcx>

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#### pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>>

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#### pub fn to_opt_poly_projection_pred( self ) -> Option<PolyProjectionPredicate<'tcx>>

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#### pub fn as_clause(self) -> Option<Clause<'tcx>>

Matches a `PredicateKind::Clause` and turns it into a `Clause`, otherwise returns `None`.

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#### pub fn expect_clause(self) -> Clause<'tcx>

Assert that the predicate is a clause.

## Trait Implementations§

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### impl<'tcx> Clone for Predicate<'tcx>

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#### fn clone(&self) -> Predicate<'tcx>

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<'tcx> Debug for Predicate<'tcx>

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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<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for Predicate<'tcx>

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#### fn decode(decoder: &mut D) -> Predicate<'tcx>

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### impl<'tcx> Display for Predicate<'tcx>

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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<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for Predicate<'tcx>

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#### fn encode(&self, e: &mut E)

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### impl<'tcx> EraseType for Predicate<'tcx>

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#### type Result = [u8; 8]

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### impl<'tcx> Flags for Predicate<'tcx>

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#### fn flags(&self) -> TypeFlags

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#### fn outer_exclusive_binder(&self) -> DebruijnIndex

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### impl<'tcx> Hash for Predicate<'tcx>

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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<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Predicate<'tcx>

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#### fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher )

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### impl IntoDiagArg for Predicate<'_>

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#### fn into_diag_arg(self) -> DiagArgValue

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### impl<'a, 'tcx> Lift<'tcx> for Predicate<'a>

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#### type Lifted = Predicate<'tcx>

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#### fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>

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### impl ParameterizedOverTcx for Predicate<'static>

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#### type Value<'tcx> = Predicate<'tcx>

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### impl<'tcx> PartialEq for Predicate<'tcx>

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#### fn eq(&self, other: &Predicate<'tcx>) -> 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<'tcx, P: PrettyPrinter<'tcx>> Print<'tcx, P> for Predicate<'tcx>

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#### fn print(&self, cx: &mut P) -> Result<(), PrintError>

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### impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Predicate<'tcx>

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#### fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( 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>(self, folder: &mut F) -> Self
where F: TypeFolder<I>,

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<'tcx> TypeSuperFoldable<TyCtxt<'tcx>> for Predicate<'tcx>

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#### fn try_super_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, folder: &mut F ) -> Result<Self, F::Error>

Provides a default fold for a recursive type of interest. This should only be called within `TypeFolder` methods, when a non-custom traversal is desired for the value of the type of interest passed to that method. For example, in `MyFolder::try_fold_ty(ty)`, it is valid to call `ty.try_super_fold_with(self)`, but any other folding should be done with `xyz.try_fold_with(self)`.
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#### fn super_fold_with<F>(self, folder: &mut F) -> Self
where F: TypeFolder<I>,

A convenient alternative to `try_super_fold_with` for use with infallible folders. Do not override this method, to ensure coherence with `try_super_fold_with`.
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### impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for Predicate<'tcx>

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#### fn super_visit_with<V: TypeVisitor<TyCtxt<'tcx>>>( &self, visitor: &mut V ) -> V::Result

Provides a default visit for a recursive type of interest. This should only be called within `TypeVisitor` methods, when a non-custom traversal is desired for the value of the type of interest passed to that method. For example, in `MyVisitor::visit_ty(ty)`, it is valid to call `ty.super_visit_with(self)`, but any other visiting should be done with `xyz.visit_with(self)`.
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### impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Predicate<'tcx>

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#### fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result

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<'tcx> Copy for Predicate<'tcx>

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### impl<'tcx> Eq for Predicate<'tcx>

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### impl<'tcx> StructuralPartialEq for Predicate<'tcx>

## Auto Trait Implementations§

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### impl<'tcx> DynSend for Predicate<'tcx>

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### impl<'tcx> DynSync for Predicate<'tcx>

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### impl<'tcx> Freeze for Predicate<'tcx>

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### impl<'tcx> !RefUnwindSafe for Predicate<'tcx>

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### impl<'tcx> Send for Predicate<'tcx>

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### impl<'tcx> Sync for Predicate<'tcx>

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### impl<'tcx> Unpin for Predicate<'tcx>

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### impl<'tcx> !UnwindSafe for Predicate<'tcx>

## 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<'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, 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<Tcx, T> DepNodeParams<Tcx> for T
where Tcx: DepContext, T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

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#### default fn fingerprint_style() -> FingerprintStyle

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#### default fn to_fingerprint(&self, tcx: Tcx) -> Fingerprint

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous).
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#### default fn to_debug_str(&self, _: Tcx) -> String

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#### default fn recover(_: Tcx, _: &DepNode) -> Option<T>

This method tries to recover the query key from the given `DepNode`, something which is needed when forcing `DepNode`s during red-green evaluation. The query system will only call this method if `fingerprint_style()` is not `FingerprintStyle::Opaque`. It is always valid to return `None` here, in which case incremental compilation will treat the query as having changed instead of forcing it.
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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<P> IntoQueryParam<P> for P

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#### fn into_query_param(self) -> P

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### impl<'tcx, T> IsSuggestable<'tcx> for T
where T: TypeVisitable<TyCtxt<'tcx>> + TypeFoldable<TyCtxt<'tcx>>,

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#### fn is_suggestable(self, tcx: TyCtxt<'tcx>, infer_suggestable: bool) -> bool

Whether this makes sense to suggest in a diagnostic. Read more
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#### fn make_suggestable( self, tcx: TyCtxt<'tcx>, infer_suggestable: bool ) -> Option<T>

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### impl<T> MaybeResult<T> for T

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#### type Error = !

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#### fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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#### fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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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<'tcx, T> ToPredicate<'tcx, T> for T

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#### fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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### impl<T> ToString for T
where T: Display + ?Sized,

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#### default fn to_string(&self) -> String

Converts the given value to a `String`. 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<I, T> TypeVisitableExt<I> for T
where I: Interner, T: TypeVisitable<I>,

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#### fn has_type_flags(&self, flags: TypeFlags) -> bool

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#### fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

Returns `true` if `self` has any late-bound regions that are either bound by `binder` or bound by some binder outside of `binder`. If `binder` is `ty::INNERMOST`, this indicates whether there are any late-bound regions that appear free.
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#### fn error_reported(&self) -> Result<(), <I as Interner>::ErrorGuaranteed>

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#### fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool

Returns `true` if this type has any regions that escape `binder` (and hence are not bound by it).
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#### fn has_escaping_bound_vars(&self) -> bool

Return `true` if this type has regions that are not a part of the type. For example, `for<'a> fn(&'a i32)` return `false`, while `fn(&'a i32)` would return `true`. The latter can occur when traversing through the former. Read more
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#### fn has_projections(&self) -> bool

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

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

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

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

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

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

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

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

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

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

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

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

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

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound.
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#### fn has_erased_regions(&self) -> bool

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

True if there are any un-erased free regions.
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#### fn is_global(&self) -> bool

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.
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#### fn has_bound_regions(&self) -> bool

True if there are any late-bound regions
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#### fn has_non_region_bound_vars(&self) -> bool

True if there are any late-bound non-region variables
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#### fn has_bound_vars(&self) -> bool

True if there are any bound variables
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#### fn still_further_specializable(&self) -> bool

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of `impl` specialization.
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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<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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#### default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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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: 8 bytes