Extract select_inherent_assoc_type_candidates
This commit is contained in:
Santiago Pastorino
parent
8694b0973a
commit
4b26bb544e
@ -27,11 +27,12 @@
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use rustc_hir::intravisit::{walk_generics, Visitor as _};
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use rustc_hir::{GenericArg, GenericArgs, OpaqueTyOrigin};
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use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
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use rustc_infer::traits::ObligationCause;
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use rustc_infer::traits::{Obligation, ObligationCause};
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use rustc_middle::middle::stability::AllowUnstable;
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use rustc_middle::ty::GenericParamDefKind;
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use rustc_middle::ty::{
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self, Const, GenericArgKind, GenericArgsRef, IsSuggestable, Ty, TyCtxt, TypeVisitableExt,
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self, Const, GenericArgKind, GenericArgsRef, IsSuggestable, ParamEnv, Predicate, Ty, TyCtxt,
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TypeVisitableExt,
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};
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use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
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use rustc_span::edit_distance::find_best_match_for_name;
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@ -1607,7 +1608,6 @@ fn lookup_inherent_assoc_ty(
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let param_env = tcx.param_env(block.owner);
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let cause = ObligationCause::misc(span, block.owner.def_id);
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let mut fulfillment_errors = Vec::new();
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let mut universes = if self_ty.has_escaping_bound_vars() {
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vec![None; self_ty.outer_exclusive_binder().as_usize()]
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} else {
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@ -1619,96 +1619,112 @@ fn lookup_inherent_assoc_ty(
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&mut universes,
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self_ty,
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|self_ty| {
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let tcx = self.tcx();
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let InferOk { value: self_ty, obligations } =
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infcx.at(&cause, param_env).normalize(self_ty);
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let mut applicable_candidates: Vec<_> = candidates
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.iter()
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.copied()
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.filter(|&(impl_, _)| {
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infcx.probe(|_| {
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let ocx = ObligationCtxt::new(infcx);
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ocx.register_obligations(obligations.clone());
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let impl_args = infcx.fresh_args_for_item(span, impl_);
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let impl_ty = tcx.type_of(impl_).instantiate(tcx, impl_args);
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let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
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// Check that the self types can be related.
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if ocx
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.eq(&ObligationCause::dummy(), param_env, impl_ty, self_ty)
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.is_err()
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{
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return false;
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}
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// Check whether the impl imposes obligations we have to worry about.
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let impl_bounds = tcx.predicates_of(impl_).instantiate(tcx, impl_args);
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let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
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let impl_obligations = traits::predicates_for_generics(
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|_, _| cause.clone(),
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param_env,
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impl_bounds,
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);
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ocx.register_obligations(impl_obligations);
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let mut errors = ocx.select_where_possible();
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if !errors.is_empty() {
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fulfillment_errors.append(&mut errors);
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return false;
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}
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true
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})
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})
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.collect();
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if applicable_candidates.len() > 1 {
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return Err(self.complain_about_ambiguous_inherent_assoc_type(
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name,
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applicable_candidates
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.into_iter()
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.map(|(_, (candidate, _))| candidate)
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.collect(),
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span,
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));
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}
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if let Some((impl_, (assoc_item, def_scope))) = applicable_candidates.pop() {
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self.check_assoc_ty(assoc_item, name, def_scope, block, span);
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// FIXME(fmease): Currently creating throwaway `parent_args` to please
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// `create_args_for_associated_item`. Modify the latter instead (or sth. similar) to
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// not require the parent args logic.
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let parent_args = ty::GenericArgs::identity_for_item(tcx, impl_);
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let args = self.create_args_for_associated_item(
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span,
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assoc_item,
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segment,
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parent_args,
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);
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let args = tcx.mk_args_from_iter(
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std::iter::once(ty::GenericArg::from(self_ty))
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.chain(args.into_iter().skip(parent_args.len())),
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);
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let ty =
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Ty::new_alias(tcx, ty::Inherent, ty::AliasTy::new(tcx, assoc_item, args));
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return Ok(Some((ty, assoc_item)));
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}
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Err(self.complain_about_inherent_assoc_type_not_found(
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let (impl_, (assoc_item, def_scope)) = self.select_inherent_assoc_type_candidates(
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infcx,
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name,
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self_ty,
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candidates,
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fulfillment_errors,
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span,
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))
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self_ty,
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cause,
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param_env,
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obligations,
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candidates,
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)?;
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self.check_assoc_ty(assoc_item, name, def_scope, block, span);
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// FIXME(fmease): Currently creating throwaway `parent_args` to please
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// `create_args_for_associated_item`. Modify the latter instead (or sth. similar) to
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// not require the parent args logic.
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let parent_args = ty::GenericArgs::identity_for_item(tcx, impl_);
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let args =
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self.create_args_for_associated_item(span, assoc_item, segment, parent_args);
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let args = tcx.mk_args_from_iter(
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std::iter::once(ty::GenericArg::from(self_ty))
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.chain(args.into_iter().skip(parent_args.len())),
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);
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let ty = Ty::new_alias(tcx, ty::Inherent, ty::AliasTy::new(tcx, assoc_item, args));
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Ok(Some((ty, assoc_item)))
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},
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)
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}
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fn select_inherent_assoc_type_candidates(
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&self,
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infcx: &InferCtxt<'tcx>,
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name: Ident,
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span: Span,
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self_ty: Ty<'tcx>,
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cause: ObligationCause<'tcx>,
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param_env: ParamEnv<'tcx>,
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obligations: Vec<Obligation<'tcx, Predicate<'tcx>>>,
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candidates: Vec<(DefId, (DefId, DefId))>,
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) -> Result<(DefId, (DefId, DefId)), ErrorGuaranteed> {
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let tcx = self.tcx();
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let mut fulfillment_errors = Vec::new();
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let applicable_candidates: Vec<_> = candidates
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.iter()
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.copied()
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.filter(|&(impl_, _)| {
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infcx.probe(|_| {
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let ocx = ObligationCtxt::new(infcx);
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ocx.register_obligations(obligations.clone());
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let impl_args = infcx.fresh_args_for_item(span, impl_);
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let impl_ty = tcx.type_of(impl_).instantiate(tcx, impl_args);
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let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
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// Check that the self types can be related.
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if ocx.eq(&ObligationCause::dummy(), param_env, impl_ty, self_ty).is_err() {
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return false;
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}
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// Check whether the impl imposes obligations we have to worry about.
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let impl_bounds = tcx.predicates_of(impl_).instantiate(tcx, impl_args);
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let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
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let impl_obligations = traits::predicates_for_generics(
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|_, _| cause.clone(),
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param_env,
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impl_bounds,
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);
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ocx.register_obligations(impl_obligations);
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let mut errors = ocx.select_where_possible();
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if !errors.is_empty() {
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fulfillment_errors.append(&mut errors);
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return false;
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}
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true
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})
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})
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.collect();
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match &applicable_candidates[..] {
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&[] => Err(self.complain_about_inherent_assoc_type_not_found(
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name,
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self_ty,
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candidates,
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fulfillment_errors,
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span,
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)),
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&[applicable_candidate] => Ok(applicable_candidate),
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&[_, ..] => Err(self.complain_about_ambiguous_inherent_assoc_type(
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name,
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applicable_candidates.into_iter().map(|(_, (candidate, _))| candidate).collect(),
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span,
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)),
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}
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}
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fn lookup_assoc_ty(
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&self,
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name: Ident,
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