diff options
Diffstat (limited to 'compiler/rustc_hir_analysis')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs | 203 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs | 50 |
2 files changed, 115 insertions, 138 deletions
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 71a5727ed6c..72ad190df7e 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 @@ -4,13 +4,12 @@ use rustc_errors::struct_span_code_err; use rustc_hir as hir; use rustc_hir::def::{DefKind, Res}; use rustc_lint_defs::builtin::UNUSED_ASSOCIATED_TYPE_BOUNDS; -use rustc_middle::span_bug; use rustc_middle::ty::fold::BottomUpFolder; use rustc_middle::ty::{ self, DynKind, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, Upcast, }; -use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span}; +use rustc_span::{ErrorGuaranteed, Span}; use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility; use rustc_trait_selection::traits::{self, hir_ty_lowering_dyn_compatibility_violations}; use rustc_type_ir::elaborate::ClauseWithSupertraitSpan; @@ -30,16 +29,16 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { &self, span: Span, hir_id: hir::HirId, - hir_trait_bounds: &[hir::PolyTraitRef<'tcx>], + hir_bounds: &[hir::PolyTraitRef<'tcx>], lifetime: &hir::Lifetime, representation: DynKind, ) -> Ty<'tcx> { let tcx = self.tcx(); + let dummy_self = tcx.types.trait_object_dummy_self; - let mut bounds = Bounds::default(); + let mut user_written_bounds = Bounds::default(); let mut potential_assoc_types = Vec::new(); - let dummy_self = self.tcx().types.trait_object_dummy_self; - for trait_bound in hir_trait_bounds.iter().rev() { + for trait_bound in hir_bounds.iter() { if let hir::BoundPolarity::Maybe(_) = trait_bound.modifiers.polarity { continue; } @@ -53,92 +52,67 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { hir::BoundConstness::Never, hir::BoundPolarity::Positive, dummy_self, - &mut bounds, + &mut user_written_bounds, PredicateFilter::SelfOnly, ) { potential_assoc_types.extend(cur_potential_assoc_types); } } - let mut trait_bounds = vec![]; - let mut projection_bounds = vec![]; - for (pred, span) in bounds.clauses() { - let bound_pred = pred.kind(); - match bound_pred.skip_binder() { - ty::ClauseKind::Trait(trait_pred) => { - assert_eq!(trait_pred.polarity, ty::PredicatePolarity::Positive); - trait_bounds.push((bound_pred.rebind(trait_pred.trait_ref), span)); - } - ty::ClauseKind::Projection(proj) => { - projection_bounds.push((bound_pred.rebind(proj), span)); - } - ty::ClauseKind::TypeOutlives(_) => { - // Do nothing, we deal with regions separately - } - ty::ClauseKind::RegionOutlives(_) - | ty::ClauseKind::ConstArgHasType(..) - | ty::ClauseKind::WellFormed(_) - | ty::ClauseKind::ConstEvaluatable(_) - | ty::ClauseKind::HostEffect(..) => { - span_bug!(span, "did not expect {pred} clause in object bounds"); - } - } - } - - // Expand trait aliases recursively and check that only one regular (non-auto) trait - // is used and no 'maybe' bounds are used. - let expanded_traits = - traits::expand_trait_aliases(tcx, trait_bounds.iter().map(|&(a, b)| (a, b))); - - let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) = - expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id())); + let (trait_bounds, mut projection_bounds) = + traits::expand_trait_aliases(tcx, user_written_bounds.clauses()); + let (regular_traits, mut auto_traits): (Vec<_>, Vec<_>) = trait_bounds + .into_iter() + .partition(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id())); + // We don't support empty trait objects. + if regular_traits.is_empty() && auto_traits.is_empty() { + let guar = + self.report_trait_object_with_no_traits_error(span, user_written_bounds.clauses()); + return Ty::new_error(tcx, guar); + } // We don't support >1 principal if regular_traits.len() > 1 { let guar = self.report_trait_object_addition_traits_error(®ular_traits); return Ty::new_error(tcx, guar); } - // We don't support empty trait objects. - if regular_traits.is_empty() && auto_traits.is_empty() { - let guar = self.report_trait_object_with_no_traits_error(span, &trait_bounds); - return Ty::new_error(tcx, guar); - } // Don't create a dyn trait if we have errors in the principal. - if let Err(guar) = trait_bounds.error_reported() { + if let Err(guar) = regular_traits.error_reported() { return Ty::new_error(tcx, guar); } // Check that there are no gross dyn-compatibility violations; // most importantly, that the supertraits don't contain `Self`, // to avoid ICEs. - for item in ®ular_traits { - let violations = - hir_ty_lowering_dyn_compatibility_violations(tcx, item.trait_ref().def_id()); - if !violations.is_empty() { - let reported = report_dyn_incompatibility( - tcx, - span, - Some(hir_id), - item.trait_ref().def_id(), - &violations, - ) - .emit(); - return Ty::new_error(tcx, reported); + for (clause, span) in user_written_bounds.clauses() { + if let Some(trait_pred) = clause.as_trait_clause() { + let violations = + hir_ty_lowering_dyn_compatibility_violations(tcx, trait_pred.def_id()); + if !violations.is_empty() { + let reported = report_dyn_incompatibility( + tcx, + span, + Some(hir_id), + trait_pred.def_id(), + &violations, + ) + .emit(); + return Ty::new_error(tcx, reported); + } } } - let mut needed_associated_types = FxIndexSet::default(); - - let principal_span = regular_traits.first().map_or(DUMMY_SP, |info| info.bottom().1); - let regular_traits_refs_spans = trait_bounds - .into_iter() - .filter(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id())); + let principal_trait = regular_traits.into_iter().next(); - for (base_trait_ref, original_span) in regular_traits_refs_spans { - let base_pred: ty::Predicate<'tcx> = base_trait_ref.upcast(tcx); + let mut needed_associated_types = FxIndexSet::default(); + if let Some((principal_trait, spans)) = &principal_trait { + let pred: ty::Predicate<'tcx> = (*principal_trait).upcast(tcx); for ClauseWithSupertraitSpan { pred, supertrait_span } in - traits::elaborate(tcx, [ClauseWithSupertraitSpan::new(base_pred, original_span)]) - .filter_only_self() + traits::elaborate(tcx, [ClauseWithSupertraitSpan::new( + pred, + *spans.last().unwrap(), + )]) + .filter_only_self() { debug!("observing object predicate `{pred:?}`"); @@ -179,7 +153,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { // } // ``` // - // Here, the user could theoretically write `dyn MyTrait<Output = X>`, + // Here, the user could theoretically write `dyn MyTrait<MyOutput = X>`, // but actually supporting that would "expand" to an infinitely-long type // `fix $ τ → dyn MyTrait<MyOutput = X, Output = <τ as MyTrait>::MyOutput`. // @@ -188,12 +162,12 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { // the discussion in #56288 for alternatives. if !references_self { // Include projections defined on supertraits. - projection_bounds.push((pred, original_span)); + projection_bounds.push((pred, supertrait_span)); } self.check_elaborated_projection_mentions_input_lifetimes( pred, - original_span, + *spans.first().unwrap(), supertrait_span, ); } @@ -202,11 +176,13 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { } } - // `dyn Trait<Assoc = Foo>` desugars to (not Rust syntax) `dyn Trait where <Self as Trait>::Assoc = Foo`. - // So every `Projection` clause is an `Assoc = Foo` bound. `associated_types` contains all associated - // types's `DefId`, so the following loop removes all the `DefIds` of the associated types that have a - // corresponding `Projection` clause - for (projection_bound, span) in &projection_bounds { + // `dyn Trait<Assoc = Foo>` desugars to (not Rust syntax) `dyn Trait where + // <Self as Trait>::Assoc = Foo`. So every `Projection` clause is an + // `Assoc = Foo` bound. `needed_associated_types` contains all associated + // types that we expect to be provided by the user, so the following loop + // removes all the associated types that have a corresponding `Projection` + // clause, either from expanding trait aliases or written by the user. + for &(projection_bound, span) in &projection_bounds { let def_id = projection_bound.item_def_id(); let trait_ref = tcx.anonymize_bound_vars( projection_bound.map_bound(|p| p.projection_term.trait_ref(tcx)), @@ -216,17 +192,17 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { tcx.emit_node_span_lint( UNUSED_ASSOCIATED_TYPE_BOUNDS, hir_id, - *span, - crate::errors::UnusedAssociatedTypeBounds { span: *span }, + span, + crate::errors::UnusedAssociatedTypeBounds { span }, ); } } if let Err(guar) = self.check_for_required_assoc_tys( - principal_span, + principal_trait.as_ref().map_or(smallvec![], |(_, spans)| spans.clone()), needed_associated_types, potential_assoc_types, - hir_trait_bounds, + hir_bounds, ) { return Ty::new_error(tcx, guar); } @@ -236,32 +212,36 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { // We remove duplicates by inserting into a `FxHashSet` to avoid re-ordering // the bounds let mut duplicates = FxHashSet::default(); - auto_traits.retain(|i| duplicates.insert(i.trait_ref().def_id())); - debug!(?regular_traits); + auto_traits.retain(|(trait_pred, _)| duplicates.insert(trait_pred.def_id())); + + debug!(?principal_trait); debug!(?auto_traits); // Erase the `dummy_self` (`trait_object_dummy_self`) used above. - let existential_trait_refs = regular_traits.iter().map(|i| { - i.trait_ref().map_bound(|trait_ref: ty::TraitRef<'tcx>| { + let principal_trait_ref = principal_trait.map(|(trait_pred, spans)| { + trait_pred.map_bound(|trait_pred| { + let trait_ref = trait_pred.trait_ref; + assert_eq!(trait_pred.polarity, ty::PredicatePolarity::Positive); assert_eq!(trait_ref.self_ty(), dummy_self); + let span = *spans.first().unwrap(); + // Verify that `dummy_self` did not leak inside default type parameters. This // could not be done at path creation, since we need to see through trait aliases. let mut missing_type_params = vec![]; - let mut references_self = false; let generics = tcx.generics_of(trait_ref.def_id); let args: Vec<_> = trait_ref .args .iter() .enumerate() - .skip(1) // Remove `Self` for `ExistentialPredicate`. + // Skip `Self` + .skip(1) .map(|(index, arg)| { if arg == dummy_self.into() { let param = &generics.own_params[index]; missing_type_params.push(param.name); Ty::new_misc_error(tcx).into() } else if arg.walk().any(|arg| arg == dummy_self.into()) { - references_self = true; let guar = self.dcx().span_delayed_bug( span, "trait object trait bounds reference `Self`", @@ -273,8 +253,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { }) .collect(); - let span = i.bottom().1; - let empty_generic_args = hir_trait_bounds.iter().any(|hir_bound| { + let empty_generic_args = hir_bounds.iter().any(|hir_bound| { hir_bound.trait_ref.path.res == Res::Def(DefKind::Trait, trait_ref.def_id) && hir_bound.span.contains(span) }); @@ -285,26 +264,11 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { empty_generic_args, ); - if references_self { - let def_id = i.bottom().0.def_id(); - struct_span_code_err!( - self.dcx(), - i.bottom().1, - E0038, - "the {} `{}` cannot be made into an object", - tcx.def_descr(def_id), - tcx.item_name(def_id), - ) - .with_note( - rustc_middle::traits::DynCompatibilityViolation::SupertraitSelf( - smallvec![], - ) - .error_msg(), - ) - .emit(); - } - - ty::ExistentialTraitRef::new(tcx, trait_ref.def_id, args) + ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef::new( + tcx, + trait_ref.def_id, + args, + )) }) }); @@ -327,21 +291,24 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { b.projection_term = replace_dummy_self_with_error(tcx, b.projection_term, guar); } - ty::ExistentialProjection::erase_self_ty(tcx, b) + ty::ExistentialPredicate::Projection(ty::ExistentialProjection::erase_self_ty( + tcx, b, + )) }) }); - let regular_trait_predicates = existential_trait_refs - .map(|trait_ref| trait_ref.map_bound(ty::ExistentialPredicate::Trait)); - let auto_trait_predicates = auto_traits.into_iter().map(|trait_ref| { - ty::Binder::dummy(ty::ExistentialPredicate::AutoTrait(trait_ref.trait_ref().def_id())) + let auto_trait_predicates = auto_traits.into_iter().map(|(trait_pred, _)| { + assert_eq!(trait_pred.polarity(), ty::PredicatePolarity::Positive); + assert_eq!(trait_pred.self_ty().skip_binder(), dummy_self); + + ty::Binder::dummy(ty::ExistentialPredicate::AutoTrait(trait_pred.def_id())) }); + // N.b. principal, projections, auto traits // FIXME: This is actually wrong with multiple principals in regards to symbol mangling - let mut v = regular_trait_predicates - .chain( - existential_projections.map(|x| x.map_bound(ty::ExistentialPredicate::Projection)), - ) + let mut v = principal_trait_ref + .into_iter() + .chain(existential_projections) .chain(auto_trait_predicates) .collect::<SmallVec<[_; 8]>>(); v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder())); diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs index 7a3d921f00e..5d751a25080 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs @@ -11,7 +11,7 @@ use rustc_hir::def_id::DefId; use rustc_middle::bug; use rustc_middle::ty::print::{PrintPolyTraitRefExt as _, PrintTraitRefExt as _}; use rustc_middle::ty::{ - self, AdtDef, Binder, GenericParamDefKind, TraitRef, Ty, TyCtxt, TypeVisitableExt, + self, AdtDef, GenericParamDefKind, Ty, TyCtxt, TypeVisitableExt, suggest_constraining_type_param, }; use rustc_session::parse::feature_err; @@ -19,8 +19,9 @@ use rustc_span::edit_distance::find_best_match_for_name; use rustc_span::{BytePos, DUMMY_SP, Ident, Span, Symbol, kw, sym}; use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility; use rustc_trait_selection::traits::{ - FulfillmentError, TraitAliasExpansionInfo, dyn_compatibility_violations_for_assoc_item, + FulfillmentError, dyn_compatibility_violations_for_assoc_item, }; +use smallvec::SmallVec; use crate::errors::{ self, AssocItemConstraintsNotAllowedHere, ManualImplementation, MissingTypeParams, @@ -720,7 +721,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { /// emit a generic note suggesting using a `where` clause to constraint instead. pub(crate) fn check_for_required_assoc_tys( &self, - principal_span: Span, + spans: SmallVec<[Span; 1]>, missing_assoc_types: FxIndexSet<(DefId, ty::PolyTraitRef<'tcx>)>, potential_assoc_types: Vec<usize>, trait_bounds: &[hir::PolyTraitRef<'_>], @@ -729,6 +730,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { return Ok(()); } + let principal_span = *spans.first().unwrap(); + let tcx = self.tcx(); // FIXME: This logic needs some more care w.r.t handling of conflicts let missing_assoc_types: Vec<_> = missing_assoc_types @@ -1124,29 +1127,36 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { pub fn report_trait_object_addition_traits_error( &self, - regular_traits: &Vec<TraitAliasExpansionInfo<'_>>, + regular_traits: &Vec<(ty::PolyTraitPredicate<'tcx>, SmallVec<[Span; 1]>)>, ) -> ErrorGuaranteed { - let first_trait = ®ular_traits[0]; - let additional_trait = ®ular_traits[1]; + // we use the last span to point at the traits themselves, + // and all other preceding spans are trait alias expansions. + let (&first_span, first_alias_spans) = regular_traits[0].1.split_last().unwrap(); + let (&second_span, second_alias_spans) = regular_traits[1].1.split_last().unwrap(); let mut err = struct_span_code_err!( self.dcx(), - additional_trait.bottom().1, + *regular_traits[1].1.first().unwrap(), E0225, "only auto traits can be used as additional traits in a trait object" ); - additional_trait.label_with_exp_info( - &mut err, - "additional non-auto trait", - "additional use", - ); - first_trait.label_with_exp_info(&mut err, "first non-auto trait", "first use"); + err.span_label(first_span, "first non-auto trait"); + for &alias_span in first_alias_spans { + err.span_label(alias_span, "first non-auto trait comes from this alias"); + } + err.span_label(second_span, "additional non-auto trait"); + for &alias_span in second_alias_spans { + err.span_label(alias_span, "second non-auto trait comes from this alias"); + } err.help(format!( "consider creating a new trait with all of these as supertraits and using that \ trait here instead: `trait NewTrait: {} {{}}`", regular_traits .iter() // FIXME: This should `print_sugared`, but also needs to integrate projection bounds... - .map(|t| t.trait_ref().print_only_trait_path().to_string()) + .map(|(pred, _)| pred + .map_bound(|pred| pred.trait_ref) + .print_only_trait_path() + .to_string()) .collect::<Vec<_>>() .join(" + "), )); @@ -1161,14 +1171,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { pub fn report_trait_object_with_no_traits_error( &self, span: Span, - trait_bounds: &Vec<(Binder<'tcx, TraitRef<'tcx>>, Span)>, + user_written_clauses: impl IntoIterator<Item = (ty::Clause<'tcx>, Span)>, ) -> ErrorGuaranteed { let tcx = self.tcx(); - let trait_alias_span = trait_bounds - .iter() - .map(|&(trait_ref, _)| trait_ref.def_id()) - .find(|&trait_ref| tcx.is_trait_alias(trait_ref)) - .map(|trait_ref| tcx.def_span(trait_ref)); + let trait_alias_span = user_written_clauses + .into_iter() + .filter_map(|(clause, _)| clause.as_trait_clause()) + .find(|trait_ref| tcx.is_trait_alias(trait_ref.def_id())) + .map(|trait_ref| tcx.def_span(trait_ref.def_id())); self.dcx().emit_err(TraitObjectDeclaredWithNoTraits { span, trait_alias_span }) } |