Trait rustc_trait_selection::traits::query::type_op::QueryTypeOp[−][src]

pub trait QueryTypeOp<'tcx>: Debug + Sized + TypeFoldable<'tcx> + 'tcx {
    type QueryResponse: TypeFoldable<'tcx>;
    fn try_fast_path(
        tcx: TyCtxt<'tcx>, 
        key: &ParamEnvAnd<'tcx, Self>
    ) -> Option<Self::QueryResponse>;

    fn perform_query(
        tcx: TyCtxt<'tcx>, 
        canonicalized: Canonicalized<'tcx, ParamEnvAnd<'tcx, Self>>
    ) -> Fallible<CanonicalizedQueryResponse<'tcx, Self::QueryResponse>>;

    fn fully_perform_into(
        query_key: ParamEnvAnd<'tcx, Self>, 
        infcx: &InferCtxt<'_, 'tcx>, 
        output_query_region_constraints: &mut QueryRegionConstraints<'tcx>
    ) -> Fallible<Self::QueryResponse> { ... }
}

“Query type ops” are type ops that are implemented using a canonical query. The Self type here contains the kernel of information needed to do the operation – TypeOp is actually implemented for ParamEnvAnd<Self>, since we always need to bring along a parameter environment as well. For query type-ops, we will first canonicalize the key and then invoke the query on the tcx, which produces the resulting query region constraints.

Associated Types

type QueryResponse: TypeFoldable<'tcx>[src]

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Required methods

fn try_fast_path(
    tcx: TyCtxt<'tcx>,
    key: &ParamEnvAnd<'tcx, Self>
) -> Option<Self::QueryResponse>[src]

Give query the option for a simple fast path that never actually hits the tcx cache lookup etc. Return Some(r) with a final result or None to do the full path.

fn perform_query(
    tcx: TyCtxt<'tcx>,
    canonicalized: Canonicalized<'tcx, ParamEnvAnd<'tcx, Self>>
) -> Fallible<CanonicalizedQueryResponse<'tcx, Self::QueryResponse>>[src]

Performs the actual query with the canonicalized key – the real work happens here. This method is not given an infcx because it shouldn’t need one – and if it had access to one, it might do things like invoke sub_regions, which would be bad, because it would create subregion relationships that are not captured in the return value.

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Provided methods

fn fully_perform_into(
    query_key: ParamEnvAnd<'tcx, Self>,
    infcx: &InferCtxt<'_, 'tcx>,
    output_query_region_constraints: &mut QueryRegionConstraints<'tcx>
) -> Fallible<Self::QueryResponse>[src]

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Implementors

impl<'tcx> QueryTypeOp<'tcx> for ImpliedOutlivesBounds<'tcx>[src]

type QueryResponse = Vec<OutlivesBound<'tcx>>

impl<'tcx> QueryTypeOp<'tcx> for DropckOutlives<'tcx>[src]

type QueryResponse = DropckOutlivesResult<'tcx>

impl<'tcx> QueryTypeOp<'tcx> for AscribeUserType<'tcx>[src]

type QueryResponse = ()

impl<'tcx> QueryTypeOp<'tcx> for Eq<'tcx>[src]

type QueryResponse = ()

impl<'tcx> QueryTypeOp<'tcx> for ProvePredicate<'tcx>[src]

type QueryResponse = ()

impl<'tcx> QueryTypeOp<'tcx> for Subtype<'tcx>[src]

type QueryResponse = ()

impl<'tcx, T> QueryTypeOp<'tcx> for Normalize<T> where
    T: Normalizable<'tcx> + 'tcx, [src]

type QueryResponse = T

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