pub enum ConstValue<'tcx> {
    Scalar(Scalar),
    ZeroSized,
    Slice {
        data: ConstAllocation<'tcx>,
        start: usize,
        end: usize,
    },
    ByRef {
        alloc: ConstAllocation<'tcx>,
        offset: Size,
    },
}
Expand description

Represents a constant value in Rust. Scalar and Slice are optimizations for array length computations, enum discriminants and the pattern matching logic.

Variants§

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Scalar(Scalar)

Used only for types with layout::abi::Scalar ABI.

Not using the enum Value to encode that this must not be Uninit.

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ZeroSized

Only used for ZSTs.

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Slice

Fields

§data: ConstAllocation<'tcx>
§start: usize
§end: usize

Used only for &[u8] and &str

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ByRef

Fields

§alloc: ConstAllocation<'tcx>

The backing memory of the value, may contain more memory than needed for just the value in order to share ConstAllocations between values

§offset: Size

Offset into alloc

A value not represented/representable by Scalar or Slice

Implementations§

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impl<'tcx> ConstValue<'tcx>

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

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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 try_to_machine_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64>

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

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pub fn from_bool(b: bool) -> Self

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pub fn from_u64(i: u64) -> Self

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pub fn from_machine_usize(i: u64, cx: &impl HasDataLayout) -> Self

Trait Implementations§

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impl<'tcx> Clone for ConstValue<'tcx>

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

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<'tcx> Debug for ConstValue<'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 ConstValue<'tcx>

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

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impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ConstValue<'tcx>

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

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impl<'tcx> Hash for ConstValue<'tcx>

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

Feeds this value into the given Hasher. Read more
1.3.0 · source§

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 ConstValue<'tcx>

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

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impl<'tcx, '__lifted> Lift<'__lifted> for ConstValue<'tcx>

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type Lifted = ConstValue<'__lifted>

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fn lift_to_tcx(self, __tcx: TyCtxt<'__lifted>) -> Option<ConstValue<'__lifted>>

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impl<'tcx> PartialEq<ConstValue<'tcx>> for ConstValue<'tcx>

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fn eq(&self, other: &ConstValue<'tcx>) -> bool

This method tests for self and other values to be equal, and is used by ==.
1.0.0 · source§

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<'tcx> for ConstValue<'tcx>

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fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
self,
_: &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<'tcx>>(self, _: &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<'tcx> TypeVisitable<'tcx> for ConstValue<'tcx>

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fn visit_with<F: TypeVisitor<'tcx>>(&self, _: &mut F) -> ControlFlow<F::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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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_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 needs_infer(&self) -> bool

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fn has_placeholders(&self) -> bool

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fn needs_subst(&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> Copy for ConstValue<'tcx>

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impl<'tcx> Eq for ConstValue<'tcx>

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impl<'tcx> StructuralEq for ConstValue<'tcx>

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impl<'tcx> StructuralPartialEq for ConstValue<'tcx>

Auto Trait Implementations§

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impl<'tcx> RefUnwindSafe for ConstValue<'tcx>

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impl<'tcx> Send for ConstValue<'tcx>

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impl<'tcx> Sync for ConstValue<'tcx>

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impl<'tcx> Unpin for ConstValue<'tcx>

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impl<'tcx> UnwindSafe for ConstValue<'tcx>

Blanket Implementations§

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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,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
T: ?Sized,

const: unstable · source§

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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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<<Tcx as DepContext>::DepKind>
) -> 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

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, R> InternIteratorElement<T, R> for T

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type Output = R

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fn intern_with<I, F>(iter: I, f: F) -> <T as InternIteratorElement<T, R>>::Outputwhere
I: Iterator<Item = T>,
F: FnOnce(&[T]) -> R,

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impl<T, U> Into<U> for Twhere
U: From<T>,

const: unstable · source§

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> 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, 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.
const: unstable · source§

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.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<Tcx, T, D> Value<Tcx, D> for Twhere
Tcx: DepContext,
D: DepKind,

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default fn from_cycle_error(tcx: Tcx, _: &[QueryInfo<D>]) -> T

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: 32 bytes

Size for each variant:

  • Scalar: 24 bytes
  • ZeroSized: 0 bytes
  • Slice: 24 bytes
  • ByRef: 16 bytes