Struct rustc_middle::ty::ParamEnv

source ·
pub struct ParamEnv<'tcx> {
    packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
}
Expand description

When type checking, we use the ParamEnv to track details about the set of where-clauses that are in scope at this particular point.

Fields§

§packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>

This packs both caller bounds and the reveal enum into one pointer.

Caller bounds are Obligations that the caller must satisfy. This is basically the set of bounds on the in-scope type parameters, translated into Obligations, and elaborated and normalized.

Use the caller_bounds() method to access.

Typically, this is Reveal::UserFacing, but during codegen we want Reveal::All.

Note: This is packed, use the reveal() method to access it.

Implementations§

source§

impl<'tcx> ParamEnv<'tcx>

source

pub fn empty() -> Self

Construct a trait environment suitable for contexts where there are no where-clauses in scope. Hidden types (like impl Trait) are left hidden, so this is suitable for ordinary type-checking.

source

pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>>

source

pub fn reveal(self) -> Reveal

source

pub fn constness(self) -> Constness

source

pub fn is_const(self) -> bool

source

pub fn reveal_all() -> Self

Construct a trait environment with no where-clauses in scope where the values of all impl Trait and other hidden types are revealed. This is suitable for monomorphized, post-typeck environments like codegen or doing optimizations.

N.B., if you want to have predicates in scope, use ParamEnv::new, or invoke param_env.with_reveal_all().

source

pub fn new(
    caller_bounds: &'tcx List<Predicate<'tcx>>,
    reveal: Reveal,
    constness: Constness
) -> Self

Construct a trait environment with the given set of predicates.

source

pub fn with_user_facing(self) -> Self

source

pub fn with_constness(self, constness: Constness) -> Self

source

pub fn with_const(self) -> Self

source

pub fn without_const(self) -> Self

source

pub fn remap_constness_with(&mut self, constness: BoundConstness)

source

pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self

Returns a new parameter environment with the same clauses, but which “reveals” the true results of projections in all cases (even for associated types that are specializable). This is the desired behavior during codegen and certain other special contexts; normally though we want to use Reveal::UserFacing, which is the default. All opaque types in the caller_bounds of the ParamEnv will be normalized to their underlying types. See PR #65989 and issue #65918 for more details

source

pub fn without_caller_bounds(self) -> Self

Returns this same environment but with no caller bounds.

source

pub fn and<T: TypeVisitable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T>

Creates a suitable environment in which to perform trait queries on the given value. When type-checking, this is simply the pair of the environment plus value. But when reveal is set to All, then if value does not reference any type parameters, we will pair it with the empty environment. This improves caching and is generally invisible.

N.B., we preserve the environment when type-checking because it is possible for the user to have wacky where-clauses like where Box<u32>: Copy, which are clearly never satisfiable. We generally want to behave as if they were true, although the surrounding function is never reachable.

Trait Implementations§

source§

impl<'tcx> Clone for ParamEnv<'tcx>

source§

fn clone(&self) -> ParamEnv<'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
source§

impl<'tcx> Debug for ParamEnv<'tcx>

source§

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
source§

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

source§

fn decode(d: &mut D) -> Self

source§

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

source§

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

source§

impl<'tcx> Hash for ParamEnv<'tcx>

source§

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
source§

impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx>

source§

fn hash_stable(
    &self,
    hcx: &mut StableHashingContext<'a>,
    hasher: &mut StableHasher
)

source§

impl<'tcx> Key for ParamEnv<'tcx>

§

type CacheSelector = DefaultCacheSelector<ParamEnv<'tcx>>

source§

fn query_crate_is_local(&self) -> bool

Given an instance of this key, what crate is it referring to? This is used to find the provider.
source§

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?
source§

fn key_as_def_id(&self) -> Option<DefId>

If the key is a DefId or DefId–equivalent, return that DefId. Otherwise, return None.
source§

fn ty_adt_id(&self) -> Option<DefId>

source§

impl<'a, 'tcx> Lift<'tcx> for ParamEnv<'a>

§

type Lifted = ParamEnv<'tcx>

source§

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

source§

impl<'tcx> PartialEq<ParamEnv<'tcx>> for ParamEnv<'tcx>

source§

fn eq(&self, other: &ParamEnv<'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.
source§

impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx>

source§

fn try_fold_with<F: FallibleTypeFolder<'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
source§

fn fold_with<F: TypeFolder<'tcx>>(self, folder: &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.
source§

impl<'tcx> TypeVisitable<'tcx> for ParamEnv<'tcx>

source§

fn visit_with<V: TypeVisitor<'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
source§

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.
source§

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).
source§

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
source§

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

source§

fn has_projections(&self) -> bool

source§

fn has_opaque_types(&self) -> bool

source§

fn has_generators(&self) -> bool

source§

fn references_error(&self) -> bool

source§

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

source§

fn has_non_region_param(&self) -> bool

source§

fn has_infer_regions(&self) -> bool

source§

fn has_infer_types(&self) -> bool

source§

fn has_non_region_infer(&self) -> bool

source§

fn needs_infer(&self) -> bool

source§

fn has_placeholders(&self) -> bool

source§

fn needs_subst(&self) -> bool

source§

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.
source§

fn has_erased_regions(&self) -> bool

source§

fn has_erasable_regions(&self) -> bool

True if there are any un-erased free regions.
source§

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.
source§

fn has_late_bound_regions(&self) -> bool

True if there are any late-bound regions
source§

fn has_non_region_late_bound(&self) -> bool

True if there are any late-bound non-region variables
source§

fn has_late_bound_vars(&self) -> bool

True if there are any late-bound variables
source§

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.
source§

impl<'tcx> Copy for ParamEnv<'tcx>

source§

impl<'tcx> Eq for ParamEnv<'tcx>

source§

impl<'tcx> StructuralEq for ParamEnv<'tcx>

source§

impl<'tcx> StructuralPartialEq for ParamEnv<'tcx>

Auto Trait Implementations§

§

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

§

impl<'tcx> !Send for ParamEnv<'tcx>

§

impl<'tcx> !Sync for ParamEnv<'tcx>

§

impl<'tcx> Unpin for ParamEnv<'tcx>

§

impl<'tcx> !UnwindSafe for ParamEnv<'tcx>

Blanket Implementations§

source§

impl<T> Any for Twhere
    T: 'static + ?Sized,

source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
source§

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

source§

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

source§

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

source§

impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
source§

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
source§

impl<Tcx, T> DepNodeParams<Tcx> for Twhere
    Tcx: DepContext,
    T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

source§

default fn fingerprint_style() -> FingerprintStyle

source§

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).
source§

default fn to_debug_str(&self, _: Tcx) -> String

source§

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.
source§

impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

source§

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

§

type Output = R

source§

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

source§

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.

source§

impl<T> MaybeResult<T> for T

§

type Error = !

source§

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

source§

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

source§

impl<T> ToOwned for Twhere
    T: Clone,

§

type Owned = T

The resulting type after obtaining ownership.
source§

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
source§

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
source§

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

source§

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

source§

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

§

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.
source§

impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

§

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.
source§

impl<Tcx, T, D> Value<Tcx, D> for Twhere
    Tcx: DepContext,
    D: DepKind,

source§

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: 8 bytes