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Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs new file mode 100644 index 000000000..081308ac7 --- /dev/null +++ b/compiler/rustc_trait_selection/src/traits/query/type_op/prove_predicate.rs @@ -0,0 +1,43 @@ +use crate::infer::canonical::{Canonicalized, CanonicalizedQueryResponse}; +use crate::traits::query::Fallible; +use rustc_middle::ty::{self, ParamEnvAnd, TyCtxt}; + +pub use rustc_middle::traits::query::type_op::ProvePredicate; + +impl<'tcx> super::QueryTypeOp<'tcx> for ProvePredicate<'tcx> { + type QueryResponse = (); + + fn try_fast_path( + tcx: TyCtxt<'tcx>, + key: &ParamEnvAnd<'tcx, Self>, + ) -> Option<Self::QueryResponse> { + // Proving Sized, very often on "obviously sized" types like + // `&T`, accounts for about 60% percentage of the predicates + // we have to prove. No need to canonicalize and all that for + // such cases. + if let ty::PredicateKind::Trait(trait_ref) = key.value.predicate.kind().skip_binder() { + if let Some(sized_def_id) = tcx.lang_items().sized_trait() { + if trait_ref.def_id() == sized_def_id { + if trait_ref.self_ty().is_trivially_sized(tcx) { + return Some(()); + } + } + } + } + + None + } + + fn perform_query( + tcx: TyCtxt<'tcx>, + mut canonicalized: Canonicalized<'tcx, ParamEnvAnd<'tcx, Self>>, + ) -> Fallible<CanonicalizedQueryResponse<'tcx, ()>> { + match canonicalized.value.value.predicate.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => { + canonicalized.value.param_env.remap_constness_with(pred.constness); + } + _ => canonicalized.value.param_env = canonicalized.value.param_env.without_const(), + } + tcx.type_op_prove_predicate(canonicalized) + } +} |