Struct rustc_trait_selection::infer::at::At

pub struct At<'a, 'tcx> {
    pub infcx: &'a InferCtxt<'tcx>,
    pub cause: &'a ObligationCause<'tcx>,
    pub param_env: ParamEnv<'tcx>,
}

Fields

infcx: &'a InferCtxt<'tcx>

cause: &'a ObligationCause<'tcx>

param_env: ParamEnv<'tcx>

Implementations

impl<'a, 'tcx> At<'a, 'tcx>

pub fn sup<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, actual: T ) -> Result<InferOk<'tcx, ()>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

Makes actual <: expected. For example, if type-checking a call like foo(x), where foo: fn(i32), you might have sup(i32, x), since the “expected” type is the type that appears in the signature.

See At::trace and Trace::sub for a version of this method that only requires T: Relate<'tcx>

pub fn sub<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, actual: T ) -> Result<InferOk<'tcx, ()>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

Makes expected <: actual.

See At::trace and Trace::sub for a version of this method that only requires T: Relate<'tcx>

pub fn eq<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, actual: T ) -> Result<InferOk<'tcx, ()>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

Makes expected <: actual.

See At::trace and Trace::eq for a version of this method that only requires T: Relate<'tcx>

pub fn relate<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, variance: Variance, actual: T ) -> Result<InferOk<'tcx, ()>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

pub fn lub<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, actual: T ) -> Result<InferOk<'tcx, T>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

Computes the least-upper-bound, or mutual supertype, of two values. The order of the arguments doesn’t matter, but since this can result in an error (e.g., if asked to compute LUB of u32 and i32), it is meaningful to call one of them the “expected type”.

See At::trace and Trace::lub for a version of this method that only requires T: Relate<'tcx>

pub fn glb<T>( self, define_opaque_types: DefineOpaqueTypes, expected: T, actual: T ) -> Result<InferOk<'tcx, T>, TypeError<'tcx>>

where T: ToTrace<'tcx>,

Computes the greatest-lower-bound, or mutual subtype, of two values. As with lub order doesn’t matter, except for error cases.

See At::trace and Trace::glb for a version of this method that only requires T: Relate<'tcx>

pub fn trace<T>(self, expected: T, actual: T) -> Trace<'a, 'tcx>

where T: ToTrace<'tcx>,

Sets the “trace” values that will be used for error-reporting, but doesn’t actually perform any operation yet (this is useful when you want to set the trace using distinct values from those you wish to operate upon).

Trait Implementations

impl<'a, 'tcx> Clone for At<'a, 'tcx>

fn clone(&self) -> At<'a, 'tcx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> NormalizeExt<'tcx> for At<'_, 'tcx>

fn normalize<T: TypeFoldable<TyCtxt<'tcx>>>(&self, value: T) -> InferOk<'tcx, T>

Normalize a value using the AssocTypeNormalizer.

This normalization should be used when the type contains inference variables or the projection may be fallible.

fn deeply_normalize<T: TypeFoldable<TyCtxt<'tcx>>>( self, value: T, fulfill_cx: &mut dyn TraitEngine<'tcx> ) -> Result<T, Vec<FulfillmentError<'tcx>>>

Deeply normalizes value, replacing all aliases which can by normalized in the current environment. In the new solver this errors in case normalization fails or is ambiguous.

In the old solver this simply uses normalizes and adds the nested obligations to the fulfill_cx. This is necessary as we otherwise end up recomputing the same goals in both a temporary and the shared context which negatively impacts performance as these don’t share caching.

FIXME(-Znext-solver): This has the same behavior as traits::fully_normalize in the new solver, but because of performance reasons, we currently reuse an existing fulfillment context in the old solver. Once we also eagerly prove goals with the old solver or have removed the old solver, remove traits::fully_normalize and rename this function to At::fully_normalize.

impl<'cx, 'tcx> QueryNormalizeExt<'tcx> for At<'cx, 'tcx>

fn query_normalize<T>(self, value: T) -> Result<Normalized<'tcx, T>, NoSolution>

where T: TypeFoldable<TyCtxt<'tcx>>,

Normalize value in the context of the inference context, yielding a resulting type, or an error if value cannot be normalized. If you don’t care about regions, you should prefer normalize_erasing_regions, which is more efficient.

If the normalization succeeds and is unambiguous, returns back the normalized value along with various outlives relations (in the form of obligations that must be discharged).

N.B., this will eventually be the main means of normalizing, but for now should be used only when we actually know that normalization will succeed, since error reporting and other details are still “under development”.

This normalization should only be used when the projection does not have possible ambiguity or may not be well-formed.

After codegen, when lifetimes do not matter, it is preferable to instead use TyCtxt::normalize_erasing_regions, which wraps this procedure.

impl<'tcx> StructurallyNormalizeExt<'tcx> for At<'_, 'tcx>

fn structurally_normalize( &self, ty: Ty<'tcx>, fulfill_cx: &mut dyn TraitEngine<'tcx> ) -> Result<Ty<'tcx>, Vec<FulfillmentError<'tcx>>>

impl<'a, 'tcx> Copy for At<'a, 'tcx>

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: 24 bytes