Struct rustc_middle::ty::ParamEnv [−][src]
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>>, Reveal, true>
This packs both caller bounds and the reveal enum into one pointer.
Caller bounds are Obligation
s that the caller must satisfy. This is
basically the set of bounds on the in-scope type parameters, translated
into Obligation
s, 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
impl<'tcx> ParamEnv<'tcx>
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pub fn empty() -> Self
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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.
pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>>
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pub fn reveal(self) -> Reveal
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pub fn reveal_all() -> Self
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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()
.
pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self
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Construct a trait environment with the given set of predicates.
pub fn with_user_facing(self) -> Self
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pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self
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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
pub fn without_caller_bounds(self) -> Self
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Returns this same environment but with no caller bounds.
pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T>
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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
impl<'tcx> Clone for ParamEnv<'tcx>
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impl<'tcx> Copy for ParamEnv<'tcx>
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impl<'tcx> Debug for ParamEnv<'tcx>
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impl<'tcx> Eq for ParamEnv<'tcx>
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impl<'tcx> Hash for ParamEnv<'tcx>
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fn hash<__H: Hasher>(&self, state: &mut __H)
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pub fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,
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H: Hasher,
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx>
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fn hash_stable(
&self,
hcx: &mut StableHashingContext<'a>,
hasher: &mut StableHasher
)
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&self,
hcx: &mut StableHashingContext<'a>,
hasher: &mut StableHasher
)
impl<'a, 'tcx> Lift<'tcx> for ParamEnv<'a>
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impl<'tcx> PartialEq<ParamEnv<'tcx>> for ParamEnv<'tcx>
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impl<'tcx> StructuralEq for ParamEnv<'tcx>
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impl<'tcx> StructuralPartialEq for ParamEnv<'tcx>
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impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx>
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fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self
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fn super_visit_with<V: TypeVisitor<'tcx>>(
&self,
visitor: &mut V
) -> ControlFlow<V::BreakTy>
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&self,
visitor: &mut V
) -> ControlFlow<V::BreakTy>
fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self
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fn visit_with<V: TypeVisitor<'tcx>>(
&self,
visitor: &mut V
) -> ControlFlow<V::BreakTy>
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&self,
visitor: &mut V
) -> ControlFlow<V::BreakTy>
fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool
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fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool
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fn has_escaping_bound_vars(&self) -> bool
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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 references_error(&self) -> bool
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fn has_param_types_or_consts(&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_infer_types_or_consts(&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
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fn has_erased_regions(&self) -> bool
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fn has_erasable_regions(&self) -> bool
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fn is_global(&self) -> bool
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fn has_late_bound_regions(&self) -> bool
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fn still_further_specializable(&self) -> bool
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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
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<'tcx, T> ArenaAllocatable<'tcx, ()> for T where
T: Copy,
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T: Copy,
pub fn allocate_on(Self, &'a Arena<'tcx>) -> &'a mut T
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pub fn allocate_from_iter(
&'a Arena<'tcx>,
impl IntoIterator<Item = T>
) -> &'a mut [T]ⓘ
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&'a Arena<'tcx>,
impl IntoIterator<Item = T>
) -> &'a mut [T]ⓘ
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<'a, T> Captures<'a> for T where
T: ?Sized,
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T: ?Sized,
impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> MaybeResult<T> for T
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type Error = !
pub fn from(Result<T, <T as MaybeResult<T>>::Error>) -> T
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pub fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>
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impl<'tcx, T> Subst<'tcx> for T where
T: TypeFoldable<'tcx>,
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T: TypeFoldable<'tcx>,
pub fn subst_spanned(Self, TyCtxt<'tcx>, &[GenericArg<'tcx>], Option<Span>) -> T
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fn subst(self, tcx: TyCtxt<'tcx>, substs: &[GenericArg<'tcx>]) -> Self
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impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.