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Extract find_candidate function
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@spastorino
spastorino committed Nov 21, 2023
1 parent 2d0b397 commit 5cfc9f3
Showing 1 changed file with 89 additions and 86 deletions.
175 changes: 89 additions & 86 deletions compiler/rustc_hir_analysis/src/astconv/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,8 @@ use rustc_infer::traits::ObligationCause;
use rustc_middle::middle::stability::AllowUnstable;
use rustc_middle::ty::GenericParamDefKind;
use rustc_middle::ty::{
self, Const, GenericArgKind, GenericArgsRef, IsSuggestable, Ty, TyCtxt, TypeVisitableExt,
self, Const, GenericArgKind, GenericArgsRef, IsSuggestable, ParamEnv, Ty, TyCtxt,
TypeVisitableExt,
};
use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
use rustc_span::edit_distance::find_best_match_for_name;
Expand Down Expand Up @@ -1607,7 +1608,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let param_env = tcx.param_env(block.owner);
let cause = ObligationCause::misc(span, block.owner.def_id);

let mut fulfillment_errors = Vec::new();
infcx.probe(|_| {
let mut universes = if self_ty.has_escaping_bound_vars() {
vec![None; self_ty.outer_exclusive_binder().as_usize()]
Expand All @@ -1620,99 +1620,102 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
&mut universes,
self_ty,
|self_ty| {
let InferOk { value: self_ty, obligations } =
infcx.at(&cause, param_env).normalize(self_ty);
self.find_candidate(
infcx, self_ty, name, segment, block, span, cause, param_env, candidates,
)
},
)
})
}

let mut applicable_candidates: Vec<_> = candidates
.iter()
.copied()
.filter(|&(impl_, _)| {
infcx.probe(|_| {
let ocx = ObligationCtxt::new(&infcx);
ocx.register_obligations(obligations.clone());

let impl_args = infcx.fresh_args_for_item(span, impl_);
let impl_ty = tcx.type_of(impl_).instantiate(tcx, impl_args);
let impl_ty = ocx.normalize(&cause, param_env, impl_ty);

// Check that the self types can be related.
if ocx
.eq(&ObligationCause::dummy(), param_env, impl_ty, self_ty)
.is_err()
{
return false;
}
fn find_candidate(
&self,
infcx: &InferCtxt<'tcx>,
self_ty: Ty<'tcx>,
name: Ident,
segment: &hir::PathSegment<'_>,
block: hir::HirId,
span: Span,
cause: ObligationCause<'tcx>,
param_env: ParamEnv<'tcx>,
candidates: Vec<(DefId, (DefId, DefId))>,
) -> Result<Option<(Ty<'tcx>, DefId)>, ErrorGuaranteed> {
let mut fulfillment_errors = Vec::new();
let tcx = self.tcx();
let InferOk { value: self_ty, obligations } =
infcx.at(&cause, param_env).normalize(self_ty);

// Check whether the impl imposes obligations we have to worry about.
let impl_bounds =
tcx.predicates_of(impl_).instantiate(tcx, impl_args);
let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
let impl_obligations = traits::predicates_for_generics(
|_, _| cause.clone(),
param_env,
impl_bounds,
);
ocx.register_obligations(impl_obligations);
let mut applicable_candidates: Vec<_> = candidates
.iter()
.copied()
.filter(|&(impl_, _)| {
infcx.probe(|_| {
let ocx = ObligationCtxt::new(&infcx);
ocx.register_obligations(obligations.clone());

let impl_args = infcx.fresh_args_for_item(span, impl_);
let impl_ty = tcx.type_of(impl_).instantiate(tcx, impl_args);
let impl_ty = ocx.normalize(&cause, param_env, impl_ty);

// Check that the self types can be related.
if ocx.eq(&ObligationCause::dummy(), param_env, impl_ty, self_ty).is_err() {
return false;
}

let mut errors = ocx.select_where_possible();
if !errors.is_empty() {
fulfillment_errors.append(&mut errors);
return false;
}
// Check whether the impl imposes obligations we have to worry about.
let impl_bounds = tcx.predicates_of(impl_).instantiate(tcx, impl_args);
let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
let impl_obligations = traits::predicates_for_generics(
|_, _| cause.clone(),
param_env,
impl_bounds,
);
ocx.register_obligations(impl_obligations);

true
})
})
.collect();

if applicable_candidates.len() > 1 {
return Err(self.complain_about_ambiguous_inherent_assoc_type(
name,
applicable_candidates
.into_iter()
.map(|(_, (candidate, _))| candidate)
.collect(),
span,
));
let mut errors = ocx.select_where_possible();
if !errors.is_empty() {
fulfillment_errors.append(&mut errors);
return false;
}

if let Some((impl_, (assoc_item, def_scope))) = applicable_candidates.pop() {
self.check_assoc_ty(assoc_item, name, def_scope, block, span);

// FIXME(fmease): Currently creating throwaway `parent_args` to please
// `create_args_for_associated_item`. Modify the latter instead (or sth. similar) to
// not require the parent args logic.
let parent_args = ty::GenericArgs::identity_for_item(tcx, impl_);
let args = self.create_args_for_associated_item(
span,
assoc_item,
segment,
parent_args,
);
let args = tcx.mk_args_from_iter(
std::iter::once(ty::GenericArg::from(self_ty))
.chain(args.into_iter().skip(parent_args.len())),
);
true
})
})
.collect();

let ty = Ty::new_alias(
tcx,
ty::Inherent,
ty::AliasTy::new(tcx, assoc_item, args),
);
if applicable_candidates.len() > 1 {
return Err(self.complain_about_ambiguous_inherent_assoc_type(
name,
applicable_candidates.into_iter().map(|(_, (candidate, _))| candidate).collect(),
span,
));
}

return Ok(Some((ty, assoc_item)));
}
if let Some((impl_, (assoc_item, def_scope))) = applicable_candidates.pop() {
self.check_assoc_ty(assoc_item, name, def_scope, block, span);

// FIXME(fmease): Currently creating throwaway `parent_args` to please
// `create_args_for_associated_item`. Modify the latter instead (or sth. similar) to
// not require the parent args logic.
let parent_args = ty::GenericArgs::identity_for_item(tcx, impl_);
let args = self.create_args_for_associated_item(span, assoc_item, segment, parent_args);
let args = tcx.mk_args_from_iter(
std::iter::once(ty::GenericArg::from(self_ty))
.chain(args.into_iter().skip(parent_args.len())),
);

Err(self.complain_about_inherent_assoc_type_not_found(
name,
self_ty,
candidates,
fulfillment_errors,
span,
))
},
)
})
let ty = Ty::new_alias(tcx, ty::Inherent, ty::AliasTy::new(tcx, assoc_item, args));

return Ok(Some((ty, assoc_item)));
}

Err(self.complain_about_inherent_assoc_type_not_found(
name,
self_ty,
candidates,
fulfillment_errors,
span,
))
}

fn lookup_assoc_ty(
Expand Down

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