diff options
Diffstat (limited to 'compiler/rustc_hir_analysis')
11 files changed, 503 insertions, 34 deletions
diff --git a/compiler/rustc_hir_analysis/src/bounds.rs b/compiler/rustc_hir_analysis/src/bounds.rs index d0c45a7c04c..7a919bb2500 100644 --- a/compiler/rustc_hir_analysis/src/bounds.rs +++ b/compiler/rustc_hir_analysis/src/bounds.rs @@ -81,6 +81,17 @@ impl<'tcx> Bounds<'tcx> { self.clauses.insert(0, (trait_ref.upcast(tcx), span)); } + /// Push a `const` or `~const` bound as a `HostEffect` predicate. + pub(crate) fn push_const_bound( + &mut self, + tcx: TyCtxt<'tcx>, + bound_trait_ref: ty::PolyTraitRef<'tcx>, + host: ty::HostPolarity, + span: Span, + ) { + self.clauses.push((bound_trait_ref.to_host_effect_clause(tcx, host), span)); + } + pub(crate) fn clauses( &self, // FIXME(effects): remove tcx diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs index 7a56b3784f8..439e6d78428 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -181,6 +181,7 @@ fn compare_method_predicate_entailment<'tcx>( }); // Create mapping from trait method to impl method. + let impl_def_id = impl_m.container_id(tcx); let trait_to_impl_args = GenericArgs::identity_for_item(tcx, impl_m.def_id).rebase_onto( tcx, impl_m.container_id(tcx), @@ -204,6 +205,24 @@ fn compare_method_predicate_entailment<'tcx>( trait_m_predicates.instantiate_own(tcx, trait_to_impl_args).map(|(predicate, _)| predicate), ); + // FIXME(effects): This should be replaced with a more dedicated method. + let check_const_if_const = tcx.constness(impl_def_id) == hir::Constness::Const; + if check_const_if_const { + // Augment the hybrid param-env with the const conditions + // of the impl header and the trait method. + hybrid_preds.extend( + tcx.const_conditions(impl_def_id) + .instantiate_identity(tcx) + .into_iter() + .chain( + tcx.const_conditions(trait_m.def_id).instantiate_own(tcx, trait_to_impl_args), + ) + .map(|(trait_ref, _)| { + trait_ref.to_host_effect_clause(tcx, ty::HostPolarity::Maybe) + }), + ); + } + let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_def_id); let param_env = ty::ParamEnv::new(tcx.mk_clauses(&hybrid_preds), Reveal::UserFacing); let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause); @@ -230,6 +249,34 @@ fn compare_method_predicate_entailment<'tcx>( ocx.register_obligation(traits::Obligation::new(tcx, cause, param_env, predicate)); } + // If we're within a const implementation, we need to make sure that the method + // does not assume stronger `~const` bounds than the trait definition. + // + // This registers the `~const` bounds of the impl method, which we will prove + // using the hybrid param-env that we earlier augmented with the const conditions + // from the impl header and trait method declaration. + if check_const_if_const { + for (const_condition, span) in + tcx.const_conditions(impl_m.def_id).instantiate_own_identity() + { + let normalize_cause = traits::ObligationCause::misc(span, impl_m_def_id); + let const_condition = ocx.normalize(&normalize_cause, param_env, const_condition); + + let cause = + ObligationCause::new(span, impl_m_def_id, ObligationCauseCode::CompareImplItem { + impl_item_def_id: impl_m_def_id, + trait_item_def_id: trait_m.def_id, + kind: impl_m.kind, + }); + ocx.register_obligation(traits::Obligation::new( + tcx, + cause, + param_env, + const_condition.to_host_effect_clause(tcx, ty::HostPolarity::Maybe), + )); + } + } + // We now need to check that the signature of the impl method is // compatible with that of the trait method. We do this by // checking that `impl_fty <: trait_fty`. @@ -1846,9 +1893,10 @@ fn compare_type_predicate_entailment<'tcx>( trait_ty: ty::AssocItem, impl_trait_ref: ty::TraitRef<'tcx>, ) -> Result<(), ErrorGuaranteed> { + let impl_def_id = impl_ty.container_id(tcx); let trait_to_impl_args = GenericArgs::identity_for_item(tcx, impl_ty.def_id).rebase_onto( tcx, - impl_ty.container_id(tcx), + impl_def_id, impl_trait_ref.args, ); @@ -1856,7 +1904,9 @@ fn compare_type_predicate_entailment<'tcx>( let trait_ty_predicates = tcx.predicates_of(trait_ty.def_id); let impl_ty_own_bounds = impl_ty_predicates.instantiate_own_identity(); - if impl_ty_own_bounds.len() == 0 { + let impl_ty_own_const_conditions = + tcx.const_conditions(impl_ty.def_id).instantiate_own_identity(); + if impl_ty_own_bounds.len() == 0 && impl_ty_own_const_conditions.len() == 0 { // Nothing to check. return Ok(()); } @@ -1881,6 +1931,23 @@ fn compare_type_predicate_entailment<'tcx>( let impl_ty_span = tcx.def_span(impl_ty_def_id); let normalize_cause = ObligationCause::misc(impl_ty_span, impl_ty_def_id); + let check_const_if_const = tcx.constness(impl_def_id) == hir::Constness::Const; + if check_const_if_const { + // Augment the hybrid param-env with the const conditions + // of the impl header and the trait assoc type. + hybrid_preds.extend( + tcx.const_conditions(impl_ty_predicates.parent.unwrap()) + .instantiate_identity(tcx) + .into_iter() + .chain( + tcx.const_conditions(trait_ty.def_id).instantiate_own(tcx, trait_to_impl_args), + ) + .map(|(trait_ref, _)| { + trait_ref.to_host_effect_clause(tcx, ty::HostPolarity::Maybe) + }), + ); + } + let param_env = ty::ParamEnv::new(tcx.mk_clauses(&hybrid_preds), Reveal::UserFacing); let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause); debug!(caller_bounds=?param_env.caller_bounds()); @@ -1901,6 +1968,27 @@ fn compare_type_predicate_entailment<'tcx>( ocx.register_obligation(traits::Obligation::new(tcx, cause, param_env, predicate)); } + if check_const_if_const { + // Validate the const conditions of the impl associated type. + for (const_condition, span) in impl_ty_own_const_conditions { + let normalize_cause = traits::ObligationCause::misc(span, impl_ty_def_id); + let const_condition = ocx.normalize(&normalize_cause, param_env, const_condition); + + let cause = + ObligationCause::new(span, impl_ty_def_id, ObligationCauseCode::CompareImplItem { + impl_item_def_id: impl_ty_def_id, + trait_item_def_id: trait_ty.def_id, + kind: impl_ty.kind, + }); + ocx.register_obligation(traits::Obligation::new( + tcx, + cause, + param_env, + const_condition.to_host_effect_clause(tcx, ty::HostPolarity::Maybe), + )); + } + } + // Check that all obligations are satisfied by the implementation's // version. let errors = ocx.select_all_or_error(); @@ -1983,7 +2071,7 @@ pub(super) fn check_type_bounds<'tcx>( ObligationCause::new(impl_ty_span, impl_ty_def_id, code) }; - let obligations: Vec<_> = tcx + let mut obligations: Vec<_> = tcx .explicit_item_bounds(trait_ty.def_id) .iter_instantiated_copied(tcx, rebased_args) .map(|(concrete_ty_bound, span)| { @@ -1991,6 +2079,22 @@ pub(super) fn check_type_bounds<'tcx>( traits::Obligation::new(tcx, mk_cause(span), param_env, concrete_ty_bound) }) .collect(); + + // Only in a const implementation do we need to check that the `~const` item bounds hold. + if tcx.constness(container_id) == hir::Constness::Const { + obligations.extend( + tcx.implied_const_bounds(trait_ty.def_id) + .iter_instantiated_copied(tcx, rebased_args) + .map(|(c, span)| { + traits::Obligation::new( + tcx, + mk_cause(span), + param_env, + c.to_host_effect_clause(tcx, ty::HostPolarity::Maybe), + ) + }), + ); + } debug!(item_bounds=?obligations); // Normalize predicates with the assumption that the GAT may always normalize diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs index 79e57984174..f0041a57742 100644 --- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs +++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs @@ -32,7 +32,8 @@ use rustc_trait_selection::traits::misc::{ use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _; use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; use rustc_trait_selection::traits::{ - self, FulfillmentError, ObligationCause, ObligationCauseCode, ObligationCtxt, WellFormedLoc, + self, FulfillmentError, Obligation, ObligationCause, ObligationCauseCode, ObligationCtxt, + WellFormedLoc, }; use rustc_type_ir::TypeFlags; use rustc_type_ir::solve::NoSolution; @@ -86,7 +87,7 @@ impl<'tcx> WfCheckingCtxt<'_, 'tcx> { self.body_def_id, ObligationCauseCode::WellFormed(loc), ); - self.ocx.register_obligation(traits::Obligation::new( + self.ocx.register_obligation(Obligation::new( self.tcx(), cause, self.param_env, @@ -1173,7 +1174,7 @@ fn check_type_defn<'tcx>( wfcx.body_def_id, ObligationCauseCode::Misc, ); - wfcx.register_obligation(traits::Obligation::new( + wfcx.register_obligation(Obligation::new( tcx, cause, wfcx.param_env, @@ -1369,6 +1370,30 @@ fn check_impl<'tcx>( obligation.cause.span = hir_self_ty.span; } } + + // Ensure that the `~const` where clauses of the trait hold for the impl. + if tcx.constness(item.owner_id.def_id) == hir::Constness::Const { + for (bound, _) in + tcx.const_conditions(trait_ref.def_id).instantiate(tcx, trait_ref.args) + { + let bound = wfcx.normalize( + item.span, + Some(WellFormedLoc::Ty(item.hir_id().expect_owner().def_id)), + bound, + ); + wfcx.register_obligation(Obligation::new( + tcx, + ObligationCause::new( + hir_self_ty.span, + wfcx.body_def_id, + ObligationCauseCode::WellFormed(None), + ), + wfcx.param_env, + bound.to_host_effect_clause(tcx, ty::HostPolarity::Maybe), + )) + } + } + debug!(?obligations); wfcx.register_obligations(obligations); } @@ -1561,7 +1586,7 @@ fn check_where_clauses<'tcx>(wfcx: &WfCheckingCtxt<'_, 'tcx>, span: Span, def_id wfcx.body_def_id, ObligationCauseCode::WhereClause(def_id.to_def_id(), DUMMY_SP), ); - traits::Obligation::new(tcx, cause, wfcx.param_env, pred) + Obligation::new(tcx, cause, wfcx.param_env, pred) }); let predicates = predicates.instantiate_identity(tcx); @@ -1852,7 +1877,7 @@ fn receiver_is_implemented<'tcx>( let tcx = wfcx.tcx(); let trait_ref = ty::TraitRef::new(tcx, receiver_trait_def_id, [receiver_ty]); - let obligation = traits::Obligation::new(tcx, cause, wfcx.param_env, trait_ref); + let obligation = Obligation::new(tcx, cause, wfcx.param_env, trait_ref); if wfcx.infcx.predicate_must_hold_modulo_regions(&obligation) { true @@ -2188,7 +2213,7 @@ impl<'tcx> WfCheckingCtxt<'_, 'tcx> { .unwrap_or(obligation_span); } - let obligation = traits::Obligation::new( + let obligation = Obligation::new( tcx, traits::ObligationCause::new( span, diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index acc21d0994b..f46b7a8bc9c 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -77,6 +77,8 @@ pub fn provide(providers: &mut Providers) { explicit_supertraits_containing_assoc_item: predicates_of::explicit_supertraits_containing_assoc_item, trait_explicit_predicates_and_bounds: predicates_of::trait_explicit_predicates_and_bounds, + const_conditions: predicates_of::const_conditions, + implied_const_bounds: predicates_of::implied_const_bounds, type_param_predicates: predicates_of::type_param_predicates, trait_def, adt_def, diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs index 69ebd3a928a..075faea3d2a 100644 --- a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs +++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs @@ -40,7 +40,16 @@ fn associated_type_bounds<'tcx>( let mut bounds = Bounds::default(); icx.lowerer().lower_bounds(item_ty, hir_bounds, &mut bounds, ty::List::empty(), filter); // Associated types are implicitly sized unless a `?Sized` bound is found - icx.lowerer().add_sized_bound(&mut bounds, item_ty, hir_bounds, None, span); + match filter { + PredicateFilter::All + | PredicateFilter::SelfOnly + | PredicateFilter::SelfThatDefines(_) + | PredicateFilter::SelfAndAssociatedTypeBounds => { + icx.lowerer().add_sized_bound(&mut bounds, item_ty, hir_bounds, None, span); + } + // `ConstIfConst` is only interested in `~const` bounds. + PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst => {} + } let trait_def_id = tcx.local_parent(assoc_item_def_id); let trait_predicates = tcx.trait_explicit_predicates_and_bounds(trait_def_id); @@ -109,10 +118,19 @@ fn remap_gat_vars_and_recurse_into_nested_projections<'tcx>( } else { // Only collect *self* type bounds if the filter is for self. match filter { - PredicateFilter::SelfOnly | PredicateFilter::SelfThatDefines(_) => { + PredicateFilter::All => {} + PredicateFilter::SelfOnly => { return None; } - PredicateFilter::All | PredicateFilter::SelfAndAssociatedTypeBounds => {} + PredicateFilter::SelfThatDefines(_) + | PredicateFilter::SelfConstIfConst + | PredicateFilter::SelfAndAssociatedTypeBounds + | PredicateFilter::ConstIfConst => { + unreachable!( + "invalid predicate filter for \ + `remap_gat_vars_and_recurse_into_nested_projections`" + ) + } } clause_ty = alias_ty.self_ty(); @@ -308,7 +326,17 @@ fn opaque_type_bounds<'tcx>( let mut bounds = Bounds::default(); icx.lowerer().lower_bounds(item_ty, hir_bounds, &mut bounds, ty::List::empty(), filter); // Opaque types are implicitly sized unless a `?Sized` bound is found - icx.lowerer().add_sized_bound(&mut bounds, item_ty, hir_bounds, None, span); + match filter { + PredicateFilter::All + | PredicateFilter::SelfOnly + | PredicateFilter::SelfThatDefines(_) + | PredicateFilter::SelfAndAssociatedTypeBounds => { + // Associated types are implicitly sized unless a `?Sized` bound is found + icx.lowerer().add_sized_bound(&mut bounds, item_ty, hir_bounds, None, span); + } + //`ConstIfConst` is only interested in `~const` bounds. + PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst => {} + } debug!(?bounds); tcx.arena.alloc_from_iter(bounds.clauses(tcx)) diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs index f9460ed5b47..ec5773d174f 100644 --- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs @@ -12,6 +12,7 @@ use rustc_span::symbol::Ident; use rustc_span::{DUMMY_SP, Span}; use tracing::{debug, instrument, trace}; +use super::item_bounds::explicit_item_bounds_with_filter; use crate::bounds::Bounds; use crate::collect::ItemCtxt; use crate::constrained_generic_params as cgp; @@ -685,29 +686,76 @@ pub(super) fn assert_only_contains_predicates_from<'tcx>( assert_eq!( trait_predicate.self_ty(), ty, - "expected `Self` predicate when computing `{filter:?}` implied bounds: {clause:?}" + "expected `Self` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" ); } ty::ClauseKind::Projection(projection_predicate) => { assert_eq!( projection_predicate.self_ty(), ty, - "expected `Self` predicate when computing `{filter:?}` implied bounds: {clause:?}" + "expected `Self` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" ); } ty::ClauseKind::TypeOutlives(outlives_predicate) => { assert_eq!( outlives_predicate.0, ty, - "expected `Self` predicate when computing `{filter:?}` implied bounds: {clause:?}" + "expected `Self` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" ); } ty::ClauseKind::RegionOutlives(_) | ty::ClauseKind::ConstArgHasType(_, _) | ty::ClauseKind::WellFormed(_) - | ty::ClauseKind::ConstEvaluatable(_) => { + | ty::ClauseKind::ConstEvaluatable(_) + | ty::ClauseKind::HostEffect(..) => { bug!( - "unexpected non-`Self` predicate when computing `{filter:?}` implied bounds: {clause:?}" + "unexpected non-`Self` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" + ); + } + } + } + } + PredicateFilter::ConstIfConst => { + for (clause, _) in bounds { + match clause.kind().skip_binder() { + ty::ClauseKind::HostEffect(ty::HostEffectPredicate { + trait_ref: _, + host: ty::HostPolarity::Maybe, + }) => {} + _ => { + bug!( + "unexpected non-`HostEffect` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" + ); + } + } + } + } + PredicateFilter::SelfConstIfConst => { + for (clause, _) in bounds { + match clause.kind().skip_binder() { + ty::ClauseKind::HostEffect(pred) => { + assert_eq!( + pred.host, + ty::HostPolarity::Maybe, + "expected `~const` predicate when computing `{filter:?}` \ + implied bounds: {clause:?}", + ); + assert_eq!( + pred.trait_ref.self_ty(), + ty, + "expected `Self` predicate when computing `{filter:?}` \ + implied bounds: {clause:?}" + ); + } + _ => { + bug!( + "unexpected non-`HostEffect` predicate when computing \ + `{filter:?}` implied bounds: {clause:?}" ); } } @@ -829,3 +877,184 @@ impl<'tcx> ItemCtxt<'tcx> { bounds.clauses(self.tcx).collect() } } + +/// Compute the conditions that need to hold for a conditionally-const item to be const. +/// That is, compute the set of `~const` where clauses for a given item. +/// +/// This query also computes the `~const` where clauses for associated types, which are +/// not "const", but which have item bounds which may be `~const`. These must hold for +/// the `~const` item bound to hold. +pub(super) fn const_conditions<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, +) -> ty::ConstConditions<'tcx> { + // This logic is spaghetti, and should be cleaned up. The current methods that are + // defined to deal with constness are very unintuitive. + if tcx.is_const_fn_raw(def_id.to_def_id()) { + // Ok, const fn or method in const trait. + } else { + match tcx.def_kind(def_id) { + DefKind::Trait => { + if !tcx.is_const_trait(def_id.to_def_id()) { + return Default::default(); + } + } + DefKind::Impl { .. } => { + // FIXME(effects): Should be using a dedicated function to + // test if this is a const trait impl. + if tcx.constness(def_id) != hir::Constness::Const { + return Default::default(); + } + } + DefKind::AssocTy | DefKind::AssocFn => { + let parent_def_id = tcx.local_parent(def_id).to_def_id(); + match tcx.associated_item(def_id).container { + ty::AssocItemContainer::TraitContainer => { + if !tcx.is_const_trait(parent_def_id) { + return Default::default(); + } + } + ty::AssocItemContainer::ImplContainer => { + // FIXME(effects): Should be using a dedicated function to + // test if this is a const trait impl. + if tcx.constness(parent_def_id) != hir::Constness::Const { + return Default::default(); + } + } + } + } + DefKind::Closure | DefKind::OpaqueTy => { + // Closures and RPITs will eventually have const conditions + // for `~const` bounds. + return Default::default(); + } + _ => return Default::default(), + } + } + + let (generics, trait_def_id_and_supertraits, has_parent) = match tcx.hir_node_by_def_id(def_id) + { + Node::Item(item) => match item.kind { + hir::ItemKind::Impl(impl_) => (impl_.generics, None, false), + hir::ItemKind::Fn(_, generics, _) => (generics, None, false), + hir::ItemKind::Trait(_, _, generics, supertraits, _) => { + (generics, Some((item.owner_id.def_id, supertraits)), false) + } + _ => return Default::default(), + }, + // While associated types are not really const, we do allow them to have `~const` + // bounds and where clauses. `const_conditions` is responsible for gathering + // these up so we can check them in `compare_type_predicate_entailment`, and + // in `HostEffect` goal computation. + Node::TraitItem(item) => match item.kind { + hir::TraitItemKind::Fn(_, _) | hir::TraitItemKind::Type(_, _) => { + (item.generics, None, true) + } + _ => return Default::default(), + }, + Node::ImplItem(item) => match item.kind { + hir::ImplItemKind::Fn(_, _) | hir::ImplItemKind::Type(_) => (item.generics, None, true), + _ => return Default::default(), + }, + _ => return Default::default(), + }; + + let icx = ItemCtxt::new(tcx, def_id); + let mut bounds = Bounds::default(); + + for pred in generics.predicates { + match pred { + hir::WherePredicate::BoundPredicate(bound_pred) => { + let ty = icx.lowerer().lower_ty_maybe_return_type_notation(bound_pred.bounded_ty); + let bound_vars = tcx.late_bound_vars(bound_pred.hir_id); + icx.lowerer().lower_bounds( + ty, + bound_pred.bounds.iter(), + &mut bounds, + bound_vars, + PredicateFilter::ConstIfConst, + ); + } + _ => {} + } + } + + if let Some((def_id, supertraits)) = trait_def_id_and_supertraits { + bounds.push_const_bound( + tcx, + ty::Binder::dummy(ty::TraitRef::identity(tcx, def_id.to_def_id())), + ty::HostPolarity::Maybe, + DUMMY_SP, + ); + + icx.lowerer().lower_bounds( + tcx.types.self_param, + supertraits.into_iter(), + &mut bounds, + ty::List::empty(), + PredicateFilter::ConstIfConst, + ); + } + + ty::ConstConditions { + parent: has_parent.then(|| tcx.local_parent(def_id).to_def_id()), + predicates: tcx.arena.alloc_from_iter(bounds.clauses(tcx).map(|(clause, span)| { + ( + clause.kind().map_bound(|clause| match clause { + ty::ClauseKind::HostEffect(ty::HostEffectPredicate { + trait_ref, + host: ty::HostPolarity::Maybe, + }) => trait_ref, + _ => bug!("converted {clause:?}"), + }), + span, + ) + })), + } +} + +pub(super) fn implied_const_bounds<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, +) -> ty::EarlyBinder<'tcx, &'tcx [(ty::PolyTraitRef<'tcx>, Span)]> { + let bounds = match tcx.hir_node_by_def_id(def_id) { + Node::Item(hir::Item { kind: hir::ItemKind::Trait(..), .. }) => { + if !tcx.is_const_trait(def_id.to_def_id()) { + return ty::EarlyBinder::bind(&[]); + } + + implied_predicates_with_filter( + tcx, + def_id.to_def_id(), + PredicateFilter::SelfConstIfConst, + ) + } + Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Type(..), .. }) => { + if !tcx.is_const_trait(tcx.local_parent(def_id).to_def_id()) { + return ty::EarlyBinder::bind(&[]); + } + + explicit_item_bounds_with_filter(tcx, def_id, PredicateFilter::ConstIfConst) + } + Node::OpaqueTy(..) => { + // We should eventually collect the `~const` bounds on opaques. + return ty::EarlyBinder::bind(&[]); + } + _ => return ty::EarlyBinder::bind(&[]), + }; + + bounds.map_bound(|bounds| { + &*tcx.arena.alloc_from_iter(bounds.iter().copied().map(|(clause, span)| { + ( + clause.kind().map_bound(|clause| match clause { + ty::ClauseKind::HostEffect(ty::HostEffectPredicate { + trait_ref, + host: ty::HostPolarity::Maybe, + }) => trait_ref, + _ => bug!("converted {clause:?}"), + }), + span, + ) + })) + }) +} diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs index 2b0e1350108..c902e85c267 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs @@ -154,7 +154,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { for hir_bound in hir_bounds { // In order to avoid cycles, when we're lowering `SelfThatDefines`, // we skip over any traits that don't define the given associated type. - if let PredicateFilter::SelfThatDefines(assoc_name) = predicate_filter { if let Some(trait_ref) = hir_bound.trait_ref() && let Some(trait_did) = trait_ref.trait_def_id() @@ -193,6 +192,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { ); } hir::GenericBound::Outlives(lifetime) => { + // `ConstIfConst` is only interested in `~const` bounds. + if matches!( + predicate_filter, + PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst + ) { + continue; + } + let region = self.lower_lifetime(lifetime, RegionInferReason::OutlivesBound); bounds.push_region_bound( self.tcx(), @@ -392,21 +399,31 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { }, ); - bounds.push_projection_bound( - tcx, - projection_term.map_bound(|projection_term| ty::ProjectionPredicate { - projection_term, - term, - }), - constraint.span, - ); + match predicate_filter { + PredicateFilter::All + | PredicateFilter::SelfOnly + | PredicateFilter::SelfThatDefines(_) + | PredicateFilter::SelfAndAssociatedTypeBounds => { + bounds.push_projection_bound( + tcx, + projection_term.map_bound(|projection_term| ty::ProjectionPredicate { + projection_term, + term, + }), + constraint.span, + ); + } + // `ConstIfConst` is only interested in `~const` bounds. + PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst => {} + } } // Lower a constraint like `Item: Debug` as found in HIR bound `T: Iterator<Item: Debug>` // to a bound involving a projection: `<T as Iterator>::Item: Debug`. hir::AssocItemConstraintKind::Bound { bounds: hir_bounds } => { match predicate_filter { - PredicateFilter::SelfOnly | PredicateFilter::SelfThatDefines(_) => {} - PredicateFilter::All | PredicateFilter::SelfAndAssociatedTypeBounds => { + PredicateFilter::All + | PredicateFilter::SelfAndAssociatedTypeBounds + | PredicateFilter::ConstIfConst => { let projection_ty = projection_term .map_bound(|projection_term| projection_term.expect_ty(self.tcx())); // Calling `skip_binder` is okay, because `lower_bounds` expects the `param_ty` @@ -421,6 +438,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { predicate_filter, ); } + PredicateFilter::SelfOnly + | PredicateFilter::SelfThatDefines(_) + | PredicateFilter::SelfConstIfConst => {} } } } diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs index 2cee7c77aa5..3449270564a 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs @@ -78,7 +78,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { ty::ClauseKind::RegionOutlives(_) | ty::ClauseKind::ConstArgHasType(..) | ty::ClauseKind::WellFormed(_) - | ty::ClauseKind::ConstEvaluatable(_) => { + | ty::ClauseKind::ConstEvaluatable(_) + | ty::ClauseKind::HostEffect(..) => { span_bug!(span, "did not expect {pred} clause in object bounds"); } } diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs index d2636c1573e..863c077a9e0 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs @@ -81,6 +81,12 @@ pub enum PredicateFilter { /// For example, given `Self: Tr<A: B>`, this would expand to `Self: Tr` /// and `<Self as Tr>::A: B`. SelfAndAssociatedTypeBounds, + + /// Filter only the `~const` bounds, which are lowered into `HostEffect` clauses. + ConstIfConst, + + /// Filter only the `~const` bounds which are *also* in the supertrait position. + SelfConstIfConst, } #[derive(Debug)] @@ -693,8 +699,49 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { bound_vars, ); - debug!(?poly_trait_ref); - bounds.push_trait_bound(tcx, poly_trait_ref, span, polarity); + match predicate_filter { + PredicateFilter::All + | PredicateFilter::SelfOnly + | PredicateFilter::SelfThatDefines(..) + | PredicateFilter::SelfAndAssociatedTypeBounds => { + debug!(?poly_trait_ref); + bounds.push_trait_bound(tcx, poly_trait_ref, span, polarity); + + match constness { + Some(ty::BoundConstness::Const) => { + if polarity == ty::PredicatePolarity::Positive { + bounds.push_const_bound( + tcx, + poly_trait_ref, + ty::HostPolarity::Const, + span, + ); + } + } + Some(ty::BoundConstness::ConstIfConst) => { + // We don't emit a const bound here, since that would mean that we + // unconditionally need to prove a `HostEffect` predicate, even when + // the predicates are being instantiated in a non-const context. This + // is instead handled in the `const_conditions` query. + } + None => {} + } + } + // On the flip side, when filtering `ConstIfConst` bounds, we only need to convert + // `~const` bounds. All other predicates are handled in their respective queries. + // + // Note that like `PredicateFilter::SelfOnly`, we don't need to do any filtering + // here because we only call this on self bounds, and deal with the recursive case + // in `lower_assoc_item_constraint`. + PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst => match constness { + Some(ty::BoundConstness::ConstIfConst) => { + if polarity == ty::PredicatePolarity::Positive { + bounds.push_const_bound(tcx, poly_trait_ref, ty::HostPolarity::Maybe, span); + } + } + None | Some(ty::BoundConstness::Const) => {} + }, + } let mut dup_constraints = FxIndexMap::default(); for constraint in trait_segment.args().constraints { diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs index 0355adfcb11..a394fc2fbb1 100644 --- a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs +++ b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs @@ -530,6 +530,7 @@ fn trait_specialization_kind<'tcx>( | ty::ClauseKind::Projection(_) | ty::ClauseKind::ConstArgHasType(..) | ty::ClauseKind::WellFormed(_) - | ty::ClauseKind::ConstEvaluatable(..) => None, + | ty::ClauseKind::ConstEvaluatable(..) + | ty::ClauseKind::HostEffect(..) => None, } } diff --git a/compiler/rustc_hir_analysis/src/outlives/explicit.rs b/compiler/rustc_hir_analysis/src/outlives/explicit.rs index f576499ecac..2c1d443f951 100644 --- a/compiler/rustc_hir_analysis/src/outlives/explicit.rs +++ b/compiler/rustc_hir_analysis/src/outlives/explicit.rs @@ -53,7 +53,8 @@ impl<'tcx> ExplicitPredicatesMap<'tcx> { | ty::ClauseKind::Projection(_) | ty::ClauseKind::ConstArgHasType(_, _) | ty::ClauseKind::WellFormed(_) - | ty::ClauseKind::ConstEvaluatable(_) => {} + | ty::ClauseKind::ConstEvaluatable(_) + | ty::ClauseKind::HostEffect(..) => {} } } |