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lcnrlcnr
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rework pointee handling for the new rigid alias approach
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1 file changed

+79
-67
lines changed
  • compiler/rustc_next_trait_solver/src/solve/normalizes_to

1 file changed

+79
-67
lines changed

‎compiler/rustc_next_trait_solver/src/solve/normalizes_to/mod.rs

+79-67
Original file line numberDiff line numberDiff line change
@@ -537,80 +537,92 @@ where
537537
let cx = ecx.cx();
538538
let metadata_def_id = cx.require_lang_item(TraitSolverLangItem::Metadata);
539539
assert_eq!(metadata_def_id, goal.predicate.def_id());
540-
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
541-
let metadata_ty = match goal.predicate.self_ty().kind() {
542-
ty::Bool
543-
| ty::Char
544-
| ty::Int(..)
545-
| ty::Uint(..)
546-
| ty::Float(..)
547-
| ty::Array(..)
548-
| ty::Pat(..)
549-
| ty::RawPtr(..)
550-
| ty::Ref(..)
551-
| ty::FnDef(..)
552-
| ty::FnPtr(..)
553-
| ty::Closure(..)
554-
| ty::CoroutineClosure(..)
555-
| ty::Infer(ty::IntVar(..) | ty::FloatVar(..))
556-
| ty::Coroutine(..)
557-
| ty::CoroutineWitness(..)
558-
| ty::Never
559-
| ty::Foreign(..)
560-
| ty::Dynamic(_, _, ty::DynStar) => Ty::new_unit(cx),
561-
562-
ty::Error(e) => Ty::new_error(cx, e),
563-
564-
ty::Str | ty::Slice(_) => Ty::new_usize(cx),
565-
566-
ty::Dynamic(_, _, ty::Dyn) => {
567-
let dyn_metadata = cx.require_lang_item(TraitSolverLangItem::DynMetadata);
568-
cx.type_of(dyn_metadata)
569-
.instantiate(cx, &[I::GenericArg::from(goal.predicate.self_ty())])
570-
}
540+
let metadata_ty = match goal.predicate.self_ty().kind() {
541+
ty::Bool
542+
| ty::Char
543+
| ty::Int(..)
544+
| ty::Uint(..)
545+
| ty::Float(..)
546+
| ty::Array(..)
547+
| ty::Pat(..)
548+
| ty::RawPtr(..)
549+
| ty::Ref(..)
550+
| ty::FnDef(..)
551+
| ty::FnPtr(..)
552+
| ty::Closure(..)
553+
| ty::CoroutineClosure(..)
554+
| ty::Infer(ty::IntVar(..) | ty::FloatVar(..))
555+
| ty::Coroutine(..)
556+
| ty::CoroutineWitness(..)
557+
| ty::Never
558+
| ty::Foreign(..)
559+
| ty::Dynamic(_, _, ty::DynStar) => Ty::new_unit(cx),
571560

572-
ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => {
573-
// This is the "fallback impl" for type parameters, unnormalizable projections
574-
// and opaque types: If the `self_ty` is `Sized`, then the metadata is `()`.
575-
// FIXME(ptr_metadata): This impl overlaps with the other impls and shouldn't
576-
// exist. Instead, `Pointee<Metadata = ()>` should be a supertrait of `Sized`.
577-
let sized_predicate = ty::TraitRef::new(
578-
cx,
579-
cx.require_lang_item(TraitSolverLangItem::Sized),
580-
[I::GenericArg::from(goal.predicate.self_ty())],
581-
);
582-
// FIXME(-Znext-solver=coinductive): Should this be `GoalSource::ImplWhereBound`?
583-
ecx.add_goal(GoalSource::Misc, goal.with(cx, sized_predicate));
584-
Ty::new_unit(cx)
585-
}
561+
ty::Error(e) => Ty::new_error(cx, e),
586562

587-
ty::Adt(def, args) if def.is_struct() => match def.struct_tail_ty(cx) {
588-
None => Ty::new_unit(cx),
589-
Some(tail_ty) => {
590-
Ty::new_projection(cx, metadata_def_id, [tail_ty.instantiate(cx, args)])
591-
}
592-
},
593-
ty::Adt(_, _) => Ty::new_unit(cx),
563+
ty::Str | ty::Slice(_) => Ty::new_usize(cx),
594564

595-
ty::Tuple(elements) => match elements.last() {
596-
None => Ty::new_unit(cx),
597-
Some(tail_ty) => Ty::new_projection(cx, metadata_def_id, [tail_ty]),
598-
},
565+
ty::Dynamic(_, _, ty::Dyn) => {
566+
let dyn_metadata = cx.require_lang_item(TraitSolverLangItem::DynMetadata);
567+
cx.type_of(dyn_metadata)
568+
.instantiate(cx, &[I::GenericArg::from(goal.predicate.self_ty())])
569+
}
599570

600-
ty::UnsafeBinder(_) => {
601-
// FIXME(unsafe_binder): Figure out how to handle pointee for unsafe binders.
602-
todo!()
571+
ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => {
572+
// This is the "fallback impl" for type parameters, unnormalizable projections
573+
// and opaque types: If the `self_ty` is `Sized`, then the metadata is `()`.
574+
// FIXME(ptr_metadata): This impl overlaps with the other impls and shouldn't
575+
// exist. Instead, `Pointee<Metadata = ()>` should be a supertrait of `Sized`.
576+
let alias_bound_result =
577+
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
578+
let sized_predicate = ty::TraitRef::new(
579+
cx,
580+
cx.require_lang_item(TraitSolverLangItem::Sized),
581+
[I::GenericArg::from(goal.predicate.self_ty())],
582+
);
583+
ecx.add_goal(GoalSource::Misc, goal.with(cx, sized_predicate));
584+
ecx.instantiate_normalizes_to_term(goal, Ty::new_unit(cx).into());
585+
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
586+
});
587+
// In case the dummy alias-bound candidate does not apply, we instead treat this projection
588+
// as rigid.
589+
return alias_bound_result.or_else(|NoSolution| {
590+
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|this| {
591+
this.structurally_instantiate_normalizes_to_term(
592+
goal,
593+
goal.predicate.alias,
594+
);
595+
this.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
596+
})
597+
});
598+
}
599+
600+
ty::Adt(def, args) if def.is_struct() => match def.struct_tail_ty(cx) {
601+
None => Ty::new_unit(cx),
602+
Some(tail_ty) => {
603+
Ty::new_projection(cx, metadata_def_id, [tail_ty.instantiate(cx, args)])
603604
}
605+
},
606+
ty::Adt(_, _) => Ty::new_unit(cx),
604607

605-
ty::Infer(
606-
ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_),
607-
)
608-
| ty::Bound(..) => panic!(
609-
"unexpected self ty `{:?}` when normalizing `<T as Pointee>::Metadata`",
610-
goal.predicate.self_ty()
611-
),
612-
};
608+
ty::Tuple(elements) => match elements.last() {
609+
None => Ty::new_unit(cx),
610+
Some(tail_ty) => Ty::new_projection(cx, metadata_def_id, [tail_ty]),
611+
},
613612

613+
ty::UnsafeBinder(_) => {
614+
// FIXME(unsafe_binder): Figure out how to handle pointee for unsafe binders.
615+
todo!()
616+
}
617+
618+
ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_))
619+
| ty::Bound(..) => panic!(
620+
"unexpected self ty `{:?}` when normalizing `<T as Pointee>::Metadata`",
621+
goal.predicate.self_ty()
622+
),
623+
};
624+
625+
ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
614626
ecx.instantiate_normalizes_to_term(goal, metadata_ty.into());
615627
ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
616628
})

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