rework pointee handling for the new rigid alias approach
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lcnr
Michael Goulet
parent
de273e459e
commit
05bd5ced2d
1 changed files with 85 additions and 73 deletions
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@ -538,80 +538,92 @@ where
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let cx = ecx.cx();
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let metadata_def_id = cx.require_lang_item(TraitSolverLangItem::Metadata);
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assert_eq!(metadata_def_id, goal.predicate.def_id());
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let metadata_ty = match goal.predicate.self_ty().kind() {
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ty::Bool
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| ty::Char
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| ty::Int(..)
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| ty::Uint(..)
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| ty::Float(..)
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| ty::Array(..)
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| ty::Pat(..)
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| ty::RawPtr(..)
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| ty::Ref(..)
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| ty::FnDef(..)
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| ty::FnPtr(..)
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| ty::Closure(..)
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| ty::CoroutineClosure(..)
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| ty::Infer(ty::IntVar(..) | ty::FloatVar(..))
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| ty::Coroutine(..)
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| ty::CoroutineWitness(..)
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| ty::Never
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| ty::Foreign(..)
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| ty::Dynamic(_, _, ty::DynStar) => Ty::new_unit(cx),
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ty::Error(e) => Ty::new_error(cx, e),
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ty::Str | ty::Slice(_) => Ty::new_usize(cx),
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ty::Dynamic(_, _, ty::Dyn) => {
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let dyn_metadata = cx.require_lang_item(TraitSolverLangItem::DynMetadata);
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cx.type_of(dyn_metadata)
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.instantiate(cx, &[I::GenericArg::from(goal.predicate.self_ty())])
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}
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ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => {
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// This is the "fallback impl" for type parameters, unnormalizable projections
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// and opaque types: If the `self_ty` is `Sized`, then the metadata is `()`.
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// FIXME(ptr_metadata): This impl overlaps with the other impls and shouldn't
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// exist. Instead, `Pointee<Metadata = ()>` should be a supertrait of `Sized`.
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let alias_bound_result =
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ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
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let sized_predicate = ty::TraitRef::new(
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cx,
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cx.require_lang_item(TraitSolverLangItem::Sized),
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[I::GenericArg::from(goal.predicate.self_ty())],
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);
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ecx.add_goal(GoalSource::Misc, goal.with(cx, sized_predicate));
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ecx.instantiate_normalizes_to_term(goal, Ty::new_unit(cx).into());
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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});
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// In case the dummy alias-bound candidate does not apply, we instead treat this projection
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// as rigid.
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return alias_bound_result.or_else(|NoSolution| {
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ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|this| {
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this.structurally_instantiate_normalizes_to_term(
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goal,
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goal.predicate.alias,
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);
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this.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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})
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});
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}
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ty::Adt(def, args) if def.is_struct() => match def.struct_tail_ty(cx) {
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None => Ty::new_unit(cx),
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Some(tail_ty) => {
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Ty::new_projection(cx, metadata_def_id, [tail_ty.instantiate(cx, args)])
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}
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},
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ty::Adt(_, _) => Ty::new_unit(cx),
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ty::Tuple(elements) => match elements.last() {
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None => Ty::new_unit(cx),
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Some(tail_ty) => Ty::new_projection(cx, metadata_def_id, [tail_ty]),
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},
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ty::UnsafeBinder(_) => {
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// FIXME(unsafe_binder): Figure out how to handle pointee for unsafe binders.
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todo!()
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}
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ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_))
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| ty::Bound(..) => panic!(
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"unexpected self ty `{:?}` when normalizing `<T as Pointee>::Metadata`",
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goal.predicate.self_ty()
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),
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};
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ecx.probe_builtin_trait_candidate(BuiltinImplSource::Misc).enter(|ecx| {
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let metadata_ty = match goal.predicate.self_ty().kind() {
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ty::Bool
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| ty::Char
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| ty::Int(..)
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| ty::Uint(..)
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| ty::Float(..)
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| ty::Array(..)
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| ty::Pat(..)
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| ty::RawPtr(..)
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| ty::Ref(..)
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| ty::FnDef(..)
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| ty::FnPtr(..)
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| ty::Closure(..)
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| ty::CoroutineClosure(..)
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| ty::Infer(ty::IntVar(..) | ty::FloatVar(..))
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| ty::Coroutine(..)
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| ty::CoroutineWitness(..)
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| ty::Never
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| ty::Foreign(..)
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| ty::Dynamic(_, _, ty::DynStar) => Ty::new_unit(cx),
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ty::Error(e) => Ty::new_error(cx, e),
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ty::Str | ty::Slice(_) => Ty::new_usize(cx),
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ty::Dynamic(_, _, ty::Dyn) => {
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let dyn_metadata = cx.require_lang_item(TraitSolverLangItem::DynMetadata);
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cx.type_of(dyn_metadata)
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.instantiate(cx, &[I::GenericArg::from(goal.predicate.self_ty())])
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}
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ty::Alias(_, _) | ty::Param(_) | ty::Placeholder(..) => {
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// This is the "fallback impl" for type parameters, unnormalizable projections
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// and opaque types: If the `self_ty` is `Sized`, then the metadata is `()`.
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// FIXME(ptr_metadata): This impl overlaps with the other impls and shouldn't
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// exist. Instead, `Pointee<Metadata = ()>` should be a supertrait of `Sized`.
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let sized_predicate = ty::TraitRef::new(
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cx,
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cx.require_lang_item(TraitSolverLangItem::Sized),
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[I::GenericArg::from(goal.predicate.self_ty())],
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);
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// FIXME(-Znext-solver=coinductive): Should this be `GoalSource::ImplWhereBound`?
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ecx.add_goal(GoalSource::Misc, goal.with(cx, sized_predicate));
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Ty::new_unit(cx)
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}
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ty::Adt(def, args) if def.is_struct() => match def.struct_tail_ty(cx) {
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None => Ty::new_unit(cx),
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Some(tail_ty) => {
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Ty::new_projection(cx, metadata_def_id, [tail_ty.instantiate(cx, args)])
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}
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},
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ty::Adt(_, _) => Ty::new_unit(cx),
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ty::Tuple(elements) => match elements.last() {
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None => Ty::new_unit(cx),
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Some(tail_ty) => Ty::new_projection(cx, metadata_def_id, [tail_ty]),
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},
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ty::UnsafeBinder(_) => {
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// FIXME(unsafe_binder): Figure out how to handle pointee for unsafe binders.
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todo!()
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}
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ty::Infer(
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ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_),
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)
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| ty::Bound(..) => panic!(
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"unexpected self ty `{:?}` when normalizing `<T as Pointee>::Metadata`",
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goal.predicate.self_ty()
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),
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};
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ecx.instantiate_normalizes_to_term(goal, metadata_ty.into());
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ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
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})
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