pub enum Const<'tcx> {
    Ty(Const<'tcx>),
    Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>),
    Val(ConstValue<'tcx>, Ty<'tcx>),
}
Expand description

Constants

Variants§

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Ty(Const<'tcx>)

This constant came from the type system.

Any way of turning ty::Const into ConstValue should go through valtree_to_const_val; this ensures that we consistently produce “clean” values without data in the padding or anything like that.

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Unevaluated(UnevaluatedConst<'tcx>, Ty<'tcx>)

An unevaluated mir constant which is not part of the type system.

Note that Ty(ty::ConstKind::Unevaluated) and this variant are not identical! Ty will always flow through a valtree, so all data not captured in the valtree is lost. This variant directly uses the evaluated result of the given constant, including e.g. data stored in padding.

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Val(ConstValue<'tcx>, Ty<'tcx>)

This constant cannot go back into the type system, as it represents something the type system cannot handle (e.g. pointers).

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impl<'tcx> Const<'tcx>

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pub fn ty(&self) -> Ty<'tcx>

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pub fn try_to_scalar(self) -> Option<Scalar>

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pub fn try_to_scalar_int(self) -> Option<ScalarInt>

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pub fn try_to_bits(self, size: Size) -> Option<u128>

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pub fn try_to_bool(self) -> Option<bool>

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pub fn eval( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, span: Option<Span> ) -> Result<ConstValue<'tcx>, ErrorHandled>

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pub fn normalize(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self

Normalizes the constant to a value or an error if possible.

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pub fn try_eval_scalar( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> Option<Scalar>

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pub fn try_eval_scalar_int( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> Option<ScalarInt>

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pub fn try_eval_bits( &self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> Option<u128>

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pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u128

Panics if the value cannot be evaluated or doesn’t contain a valid integer of the given type.

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pub fn try_eval_target_usize( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> Option<u64>

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pub fn eval_target_usize( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> u64

Panics if the value cannot be evaluated or doesn’t contain a valid usize.

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pub fn try_eval_bool( self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx> ) -> Option<bool>

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pub fn from_value(val: ConstValue<'tcx>, ty: Ty<'tcx>) -> Self

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pub fn from_bits( tcx: TyCtxt<'tcx>, bits: u128, param_env_ty: ParamEnvAnd<'tcx, Ty<'tcx>> ) -> Self

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pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self

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pub fn zero_sized(ty: Ty<'tcx>) -> Self

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pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self

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pub fn from_scalar(_tcx: TyCtxt<'tcx>, s: Scalar, ty: Ty<'tcx>) -> Self

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pub fn from_anon_const( tcx: TyCtxt<'tcx>, def: LocalDefId, param_env: ParamEnv<'tcx> ) -> Self

Literals are converted to Const::Val, const generic parameters are eagerly converted to a constant, everything else becomes Unevaluated.

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pub fn from_ty_const(c: Const<'tcx>, tcx: TyCtxt<'tcx>) -> Self

Trait Implementations§

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impl<'tcx> Clone for Const<'tcx>

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fn clone(&self) -> Const<'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 Const<'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 Const<'tcx>

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

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impl<'tcx> Display for Const<'tcx>

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fn fmt(&self, fmt: &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 Const<'tcx>

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

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impl<'tcx> EraseType for Const<'tcx>

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type Result = [u8; 40]

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impl<'tcx> Hash for Const<'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 Const<'tcx>

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

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impl<'tcx> Key for Const<'tcx>

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type CacheSelector = DefaultCacheSelector<Const<'tcx>>

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fn default_span(&self, _: TyCtxt<'_>) -> Span

In the event that a cycle occurs, if no explicit span has been given for a query with key self, what span should we use?
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fn key_as_def_id(&self) -> Option<DefId>

If the key is a DefId or DefId–equivalent, return that DefId. Otherwise, return None.
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fn ty_adt_id(&self) -> Option<DefId>

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impl<'tcx> PartialEq<Const<'tcx>> for Const<'tcx>

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fn eq(&self, other: &Const<'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> TypeFoldable<TyCtxt<'tcx>> for Const<'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) -> Selfwhere 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> TypeVisitable<TyCtxt<'tcx>> for Const<'tcx>

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fn visit_with<__V: TypeVisitor<TyCtxt<'tcx>>>( &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<'tcx> Copy for Const<'tcx>

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impl<'tcx> Eq for Const<'tcx>

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impl<'tcx> StructuralEq for Const<'tcx>

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impl<'tcx> StructuralPartialEq for Const<'tcx>

Auto Trait Implementations§

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impl<'tcx> !RefUnwindSafe for Const<'tcx>

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impl<'tcx> Send for Const<'tcx>

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impl<'tcx> Sync for Const<'tcx>

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impl<'tcx> Unpin for Const<'tcx>

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impl<'tcx> !UnwindSafe for Const<'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 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<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for Twhere 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 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, R> CollectAndApply<T, R> for T

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fn collect_and_apply<I, F>(iter: I, f: F) -> Rwhere 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 Twhere 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 DepNodes 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<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<P> IntoQueryParam<P> for P

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impl<'tcx, T> IsSuggestable<'tcx> for Twhere 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> 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<'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 Twhere 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 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.
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impl<'tcx, T> TypeVisitableExt<'tcx> for Twhere T: TypeVisitable<TyCtxt<'tcx>>,

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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 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_type_flags(&self, flags: TypeFlags) -> bool

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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_generators(&self) -> bool

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fn references_error(&self) -> bool

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fn error_reported(&self) -> Result<(), ErrorGuaranteed>

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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_late_bound_regions(&self) -> bool

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

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

True if there are any late-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<Tcx, T> Value<Tcx> for Twhere Tcx: DepContext,

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default fn from_cycle_error( tcx: Tcx, cycle: &[QueryInfo], _guar: ErrorGuaranteed ) -> T

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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: 40 bytes

Size for each variant:

  • Ty: 8 bytes
  • Unevaluated: 32 bytes
  • Val: 32 bytes