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use crate::infer::canonical::{Canonical, CanonicalQueryResponse};
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::Clause(ty::Clause::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: Canonical<'tcx, ParamEnvAnd<'tcx, Self>>,
) -> Fallible<CanonicalQueryResponse<'tcx, ()>> {
match canonicalized.value.value.predicate.kind().skip_binder() {
ty::PredicateKind::Clause(ty::Clause::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)
}
}
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