Struct rustc_hir_analysis::collect::ItemCtxt

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pub struct ItemCtxt<'tcx> {
    tcx: TyCtxt<'tcx>,
    item_def_id: LocalDefId,
    tainted_by_errors: Cell<Option<ErrorGuaranteed>>,
}
Expand description

Context specific to some particular item. This is what implements HirTyLowerer.

§ItemCtxt vs FnCtxt

ItemCtxt is primarily used to type-check item signatures and lower them from HIR to their ty::Ty representation, which is exposed using HirTyLowerer. It’s also used for the bodies of items like structs where the body (the fields) are just signatures.

This is in contrast to FnCtxt, which is used to type-check bodies of functions, closures, and consts – anywhere that expressions and statements show up.

An important thing to note is that ItemCtxt does no inference – it has no InferCtxt – while FnCtxt does do inference.

§Trait predicates

ItemCtxt has information about the predicates that are defined on the trait. Unfortunately, this predicate information is available in various different forms at various points in the process. So we can’t just store a pointer to e.g., the HIR or the parsed ty form, we have to be more flexible. To this end, the ItemCtxt is parameterized by a DefId that it uses to satisfy probe_ty_param_bounds requests, drawing the information from the HIR (hir::Generics), recursively.

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§tcx: TyCtxt<'tcx>§item_def_id: LocalDefId§tainted_by_errors: Cell<Option<ErrorGuaranteed>>

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impl<'tcx> ItemCtxt<'tcx>

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fn probe_ty_param_bounds_in_generics( &self, hir_generics: &'tcx Generics<'tcx>, param_def_id: LocalDefId, ty: Ty<'tcx>, filter: PredicateFilter ) -> Vec<(Clause<'tcx>, Span)>

Finds bounds from hir::Generics.

This requires scanning through the HIR. We do this to avoid having to lower all the bounds, which would create artificial cycles. Instead, we can only lower the bounds for a type parameter X if X::Foo is used.

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fn bound_defines_assoc_item( &self, b: &GenericBound<'_>, assoc_name: Ident ) -> bool

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impl<'tcx> ItemCtxt<'tcx>

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pub fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx>

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pub fn lower_ty(&self, hir_ty: &Ty<'tcx>) -> Ty<'tcx>

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pub fn hir_id(&self) -> HirId

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pub fn node(&self) -> Node<'tcx>

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

Trait Implementations§

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impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx>

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fn tcx(&self) -> TyCtxt<'tcx>

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fn item_def_id(&self) -> DefId

Returns the DefId of the overarching item whose constituents get lowered.
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fn allow_infer(&self) -> bool

Returns true if the current context allows the use of inference variables.
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fn re_infer(&self, _: Option<&GenericParamDef>, _: Span) -> Option<Region<'tcx>>

Returns the region to use when a lifetime is omitted (and not elided).
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fn ty_infer(&self, _: Option<&GenericParamDef>, span: Span) -> Ty<'tcx>

Returns the type to use when a type is omitted.
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fn ct_infer( &self, ty: Ty<'tcx>, _: Option<&GenericParamDef>, span: Span ) -> Const<'tcx>

Returns the const to use when a const is omitted.
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fn probe_ty_param_bounds( &self, span: Span, def_id: LocalDefId, assoc_name: Ident ) -> GenericPredicates<'tcx>

Probe bounds in scope where the bounded type coincides with the given type parameter. Read more
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fn lower_assoc_ty( &self, span: Span, item_def_id: DefId, item_segment: &PathSegment<'tcx>, poly_trait_ref: PolyTraitRef<'tcx> ) -> Ty<'tcx>

Lower an associated type to a projection. Read more
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fn probe_adt(&self, _span: Span, ty: Ty<'tcx>) -> Option<AdtDef<'tcx>>

Returns AdtDef if ty is an ADT. Read more
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fn record_ty(&self, _hir_id: HirId, _ty: Ty<'tcx>, _span: Span)

Record the lowered type of a HIR node in this context.
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fn infcx(&self) -> Option<&InferCtxt<'tcx>>

The inference context of the lowering context if applicable.
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fn set_tainted_by_errors(&self, err: ErrorGuaranteed)

Taint the context with errors. Read more
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fn lowerer(&self) -> &dyn HirTyLowerer<'tcx>
where Self: Sized,

Convenience method for coercing the lowering context into a trait object type. Read more

Auto Trait Implementations§

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impl<'tcx> DynSend for ItemCtxt<'tcx>

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impl<'tcx> !DynSync for ItemCtxt<'tcx>

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impl<'tcx> !Freeze for ItemCtxt<'tcx>

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

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

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

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impl<'tcx> Unpin for ItemCtxt<'tcx>

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impl<'tcx> !UnwindSafe for ItemCtxt<'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> 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<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<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<P> IntoQueryParam<P> for P

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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, 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, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

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fn upcast(self, interner: I) -> U

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impl<I, T> UpcastFrom<I, T> for T

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fn upcast_from(from: T, _tcx: I) -> T

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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,

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: 16 bytes