Trait rustc_trait_selection::traits::query::type_op::QueryTypeOp
source · pub trait QueryTypeOp<'tcx>: Debug + Copy + TypeFoldable<TyCtxt<'tcx>> + 'tcx {
type QueryResponse: TypeFoldable<TyCtxt<'tcx>>;
// Required methods
fn try_fast_path(
tcx: TyCtxt<'tcx>,
key: &ParamEnvAnd<'tcx, Self>,
) -> Option<Self::QueryResponse>;
fn perform_query(
tcx: TyCtxt<'tcx>,
canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Self>>,
) -> Result<CanonicalQueryResponse<'tcx, Self::QueryResponse>, NoSolution>;
fn perform_locally_with_next_solver(
ocx: &ObligationCtxt<'_, 'tcx>,
key: ParamEnvAnd<'tcx, Self>,
) -> Result<Self::QueryResponse, NoSolution>;
// Provided method
fn fully_perform_into(
query_key: ParamEnvAnd<'tcx, Self>,
infcx: &InferCtxt<'tcx>,
output_query_region_constraints: &mut QueryRegionConstraints<'tcx>,
span: Span,
) -> Result<(Self::QueryResponse, Option<Canonical<'tcx, ParamEnvAnd<'tcx, Self>>>, Vec<PredicateObligation<'tcx>>, Certainty), NoSolution> { ... }
}
Expand description
“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.
Required Associated Types§
type QueryResponse: TypeFoldable<TyCtxt<'tcx>>
Required Methods§
sourcefn try_fast_path(
tcx: TyCtxt<'tcx>,
key: &ParamEnvAnd<'tcx, Self>,
) -> Option<Self::QueryResponse>
fn try_fast_path( tcx: TyCtxt<'tcx>, key: &ParamEnvAnd<'tcx, Self>, ) -> Option<Self::QueryResponse>
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.
sourcefn perform_query(
tcx: TyCtxt<'tcx>,
canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Self>>,
) -> Result<CanonicalQueryResponse<'tcx, Self::QueryResponse>, NoSolution>
fn perform_query( tcx: TyCtxt<'tcx>, canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, Self>>, ) -> Result<CanonicalQueryResponse<'tcx, Self::QueryResponse>, NoSolution>
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.
sourcefn perform_locally_with_next_solver(
ocx: &ObligationCtxt<'_, 'tcx>,
key: ParamEnvAnd<'tcx, Self>,
) -> Result<Self::QueryResponse, NoSolution>
fn perform_locally_with_next_solver( ocx: &ObligationCtxt<'_, 'tcx>, key: ParamEnvAnd<'tcx, Self>, ) -> Result<Self::QueryResponse, NoSolution>
In the new trait solver, we already do caching in the solver itself, so there’s no need to canonicalize and cache via the query system. Additionally, even if we were to canonicalize, we’d still need to make sure to feed it predefined opaque types and the defining anchor and that would require duplicating all of the tcx queries. Instead, just perform these ops locally.