diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/astconv/bounds.rs | 23 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/astconv/mod.rs | 406 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/astconv/object_safety.rs | 408 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/check/compare_impl_item.rs | 9 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/collect.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/collect/predicates_of.rs | 7 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/errors.rs | 10 |
7 files changed, 454 insertions, 411 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/bounds.rs b/compiler/rustc_hir_analysis/src/astconv/bounds.rs index 89677141f38..a6ee7215617 100644 --- a/compiler/rustc_hir_analysis/src/astconv/bounds.rs +++ b/compiler/rustc_hir_analysis/src/astconv/bounds.rs @@ -386,11 +386,10 @@ impl<'tcx> dyn AstConv<'tcx> + '_ { .type_of(param.def_id) .no_bound_vars() .expect("ct params cannot have early bound vars"); - tcx.mk_const( - ty::ConstKind::Bound( - ty::INNERMOST, - ty::BoundVar::from_usize(num_bound_vars), - ), + ty::Const::new_bound( + tcx, + ty::INNERMOST, + ty::BoundVar::from_usize(num_bound_vars), ty, ) .into() @@ -529,13 +528,13 @@ impl<'tcx> dyn AstConv<'tcx> + '_ { let reported = err.emit(); term = match def_kind { hir::def::DefKind::AssocTy => tcx.ty_error(reported).into(), - hir::def::DefKind::AssocConst => tcx - .const_error( - tcx.type_of(assoc_item_def_id) - .subst(tcx, projection_ty.skip_binder().substs), - reported, - ) - .into(), + hir::def::DefKind::AssocConst => ty::Const::new_error( + tcx, + reported, + tcx.type_of(assoc_item_def_id) + .subst(tcx, projection_ty.skip_binder().substs), + ) + .into(), _ => unreachable!(), }; } diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs index 1d5e4ac55f8..a6503e032c7 100644 --- a/compiler/rustc_hir_analysis/src/astconv/mod.rs +++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs @@ -6,14 +6,13 @@ mod bounds; mod errors; pub mod generics; mod lint; +mod object_safety; use crate::astconv::errors::prohibit_assoc_ty_binding; use crate::astconv::generics::{check_generic_arg_count, create_substs_for_generic_args}; use crate::bounds::Bounds; use crate::collect::HirPlaceholderCollector; -use crate::errors::{ - AmbiguousLifetimeBound, TraitObjectDeclaredWithNoTraits, TypeofReservedKeywordUsed, -}; +use crate::errors::{AmbiguousLifetimeBound, TypeofReservedKeywordUsed}; use crate::middle::resolve_bound_vars as rbv; use crate::require_c_abi_if_c_variadic; use rustc_ast::TraitObjectSyntax; @@ -31,24 +30,17 @@ use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt}; use rustc_infer::traits::ObligationCause; use rustc_middle::middle::stability::AllowUnstable; use rustc_middle::ty::subst::{self, GenericArgKind, InternalSubsts, SubstsRef}; -use rustc_middle::ty::DynKind; use rustc_middle::ty::GenericParamDefKind; -use rustc_middle::ty::ToPredicate; use rustc_middle::ty::{self, Const, IsSuggestable, Ty, TyCtxt, TypeVisitableExt}; use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS; use rustc_span::edit_distance::find_best_match_for_name; use rustc_span::symbol::{kw, Ident, Symbol}; use rustc_span::{sym, Span, DUMMY_SP}; use rustc_target::spec::abi; -use rustc_trait_selection::traits::error_reporting::report_object_safety_error; use rustc_trait_selection::traits::wf::object_region_bounds; -use rustc_trait_selection::traits::{ - self, astconv_object_safety_violations, NormalizeExt, ObligationCtxt, -}; +use rustc_trait_selection::traits::{self, NormalizeExt, ObligationCtxt}; use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; -use smallvec::{smallvec, SmallVec}; -use std::collections::BTreeSet; use std::fmt::Display; use std::slice; @@ -482,7 +474,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self.astconv.ct_infer(ty, Some(param), inf.span).into() } else { self.inferred_params.push(inf.span); - tcx.const_error_misc(ty).into() + ty::Const::new_misc_error(tcx, ty).into() } } _ => unreachable!(), @@ -537,7 +529,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { .no_bound_vars() .expect("const parameter types cannot be generic"); if let Err(guar) = ty.error_reported() { - return tcx.const_error(ty, guar).into(); + return ty::Const::new_error(tcx, guar, ty).into(); } if !infer_args && has_default { tcx.const_param_default(param.def_id).subst(tcx, substs.unwrap()).into() @@ -546,7 +538,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { self.astconv.ct_infer(ty, Some(param), self.span).into() } else { // We've already errored above about the mismatch. - tcx.const_error_misc(ty).into() + ty::Const::new_misc_error(tcx, ty).into() } } } @@ -926,380 +918,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { } } - fn conv_object_ty_poly_trait_ref( - &self, - span: Span, - hir_trait_bounds: &[hir::PolyTraitRef<'_>], - lifetime: &hir::Lifetime, - borrowed: bool, - representation: DynKind, - ) -> Ty<'tcx> { - let tcx = self.tcx(); - - let mut 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() { - if let GenericArgCountResult { - correct: - Err(GenericArgCountMismatch { invalid_args: cur_potential_assoc_types, .. }), - .. - } = self.instantiate_poly_trait_ref( - &trait_bound.trait_ref, - trait_bound.span, - ty::BoundConstness::NotConst, - ty::ImplPolarity::Positive, - dummy_self, - &mut bounds, - false, - // FIXME: This should be `true`, but we don't really handle - // associated type bounds or type aliases in objects in a way - // that makes this meaningful, I think. - OnlySelfBounds(false), - ) { - 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::ImplPolarity::Positive); - trait_bounds.push(( - bound_pred.rebind(trait_pred.trait_ref), - span, - trait_pred.constness, - )); - } - 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(_) => { - bug!() - } - } - } - - // 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 - .filter(|i| i.trait_ref().self_ty().skip_binder() == dummy_self) - .partition(|i| tcx.trait_is_auto(i.trait_ref().def_id())); - if regular_traits.len() > 1 { - let first_trait = ®ular_traits[0]; - let additional_trait = ®ular_traits[1]; - let mut err = struct_span_err!( - tcx.sess, - additional_trait.bottom().1, - 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.help(format!( - "consider creating a new trait with all of these as supertraits and using that \ - trait here instead: `trait NewTrait: {} {{}}`", - regular_traits - .iter() - .map(|t| t.trait_ref().print_only_trait_path().to_string()) - .collect::<Vec<_>>() - .join(" + "), - )); - err.note( - "auto-traits like `Send` and `Sync` are traits that have special properties; \ - for more information on them, visit \ - <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>", - ); - err.emit(); - } - - if regular_traits.is_empty() && auto_traits.is_empty() { - 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 reported = - tcx.sess.emit_err(TraitObjectDeclaredWithNoTraits { span, trait_alias_span }); - return tcx.ty_error(reported); - } - - // Check that there are no gross object safety violations; - // most importantly, that the supertraits don't contain `Self`, - // to avoid ICEs. - for item in ®ular_traits { - let object_safety_violations = - astconv_object_safety_violations(tcx, item.trait_ref().def_id()); - if !object_safety_violations.is_empty() { - let reported = report_object_safety_error( - tcx, - span, - item.trait_ref().def_id(), - &object_safety_violations, - ) - .emit(); - return tcx.ty_error(reported); - } - } - - // Use a `BTreeSet` to keep output in a more consistent order. - let mut associated_types: FxHashMap<Span, BTreeSet<DefId>> = FxHashMap::default(); - - let regular_traits_refs_spans = trait_bounds - .into_iter() - .filter(|(trait_ref, _, _)| !tcx.trait_is_auto(trait_ref.def_id())); - - for (base_trait_ref, span, constness) in regular_traits_refs_spans { - assert_eq!(constness, ty::BoundConstness::NotConst); - let base_pred: ty::Predicate<'tcx> = base_trait_ref.to_predicate(tcx); - for pred in traits::elaborate(tcx, [base_pred]) { - debug!("conv_object_ty_poly_trait_ref: observing object predicate `{:?}`", pred); - - let bound_predicate = pred.kind(); - match bound_predicate.skip_binder() { - ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => { - let pred = bound_predicate.rebind(pred); - associated_types.entry(span).or_default().extend( - tcx.associated_items(pred.def_id()) - .in_definition_order() - .filter(|item| item.kind == ty::AssocKind::Type) - .filter(|item| item.opt_rpitit_info.is_none()) - .map(|item| item.def_id), - ); - } - ty::PredicateKind::Clause(ty::ClauseKind::Projection(pred)) => { - let pred = bound_predicate.rebind(pred); - // A `Self` within the original bound will be substituted with a - // `trait_object_dummy_self`, so check for that. - let references_self = match pred.skip_binder().term.unpack() { - ty::TermKind::Ty(ty) => ty.walk().any(|arg| arg == dummy_self.into()), - ty::TermKind::Const(c) => { - c.ty().walk().any(|arg| arg == dummy_self.into()) - } - }; - - // If the projection output contains `Self`, force the user to - // elaborate it explicitly to avoid a lot of complexity. - // - // The "classically useful" case is the following: - // ``` - // trait MyTrait: FnMut() -> <Self as MyTrait>::MyOutput { - // type MyOutput; - // } - // ``` - // - // Here, the user could theoretically write `dyn MyTrait<Output = X>`, - // but actually supporting that would "expand" to an infinitely-long type - // `fix $ τ → dyn MyTrait<MyOutput = X, Output = <τ as MyTrait>::MyOutput`. - // - // Instead, we force the user to write - // `dyn MyTrait<MyOutput = X, Output = X>`, which is uglier but works. See - // the discussion in #56288 for alternatives. - if !references_self { - // Include projections defined on supertraits. - projection_bounds.push((pred, span)); - } - } - _ => (), - } - } - } - - // `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, _) in &projection_bounds { - for def_ids in associated_types.values_mut() { - def_ids.remove(&projection_bound.projection_def_id()); - } - } - - self.complain_about_missing_associated_types( - associated_types, - potential_assoc_types, - hir_trait_bounds, - ); - - // De-duplicate auto traits so that, e.g., `dyn Trait + Send + Send` is the same as - // `dyn Trait + Send`. - // 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: {:?}", regular_traits); - debug!("auto_traits: {:?}", 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>| { - assert_eq!(trait_ref.self_ty(), dummy_self); - - // 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 substs: Vec<_> = trait_ref - .substs - .iter() - .enumerate() - .skip(1) // Remove `Self` for `ExistentialPredicate`. - .map(|(index, arg)| { - if arg == dummy_self.into() { - let param = &generics.params[index]; - missing_type_params.push(param.name); - return tcx.ty_error_misc().into(); - } else if arg.walk().any(|arg| arg == dummy_self.into()) { - references_self = true; - return tcx.ty_error_misc().into(); - } - arg - }) - .collect(); - let substs = tcx.mk_substs(&substs); - - let span = i.bottom().1; - let empty_generic_args = hir_trait_bounds.iter().any(|hir_bound| { - hir_bound.trait_ref.path.res == Res::Def(DefKind::Trait, trait_ref.def_id) - && hir_bound.span.contains(span) - }); - self.complain_about_missing_type_params( - missing_type_params, - trait_ref.def_id, - span, - empty_generic_args, - ); - - if references_self { - let def_id = i.bottom().0.def_id(); - let mut err = struct_span_err!( - tcx.sess, - i.bottom().1, - E0038, - "the {} `{}` cannot be made into an object", - tcx.def_descr(def_id), - tcx.item_name(def_id), - ); - err.note( - rustc_middle::traits::ObjectSafetyViolation::SupertraitSelf(smallvec![]) - .error_msg(), - ); - err.emit(); - } - - ty::ExistentialTraitRef { def_id: trait_ref.def_id, substs } - }) - }); - - let existential_projections = projection_bounds - .iter() - // We filter out traits that don't have `Self` as their self type above, - // we need to do the same for projections. - .filter(|(bound, _)| bound.skip_binder().self_ty() == dummy_self) - .map(|(bound, _)| { - bound.map_bound(|mut b| { - assert_eq!(b.projection_ty.self_ty(), dummy_self); - - // Like for trait refs, verify that `dummy_self` did not leak inside default type - // parameters. - let references_self = b.projection_ty.substs.iter().skip(1).any(|arg| { - if arg.walk().any(|arg| arg == dummy_self.into()) { - return true; - } - false - }); - if references_self { - let guar = tcx.sess.delay_span_bug( - span, - "trait object projection bounds reference `Self`", - ); - let substs: Vec<_> = b - .projection_ty - .substs - .iter() - .map(|arg| { - if arg.walk().any(|arg| arg == dummy_self.into()) { - return tcx.ty_error(guar).into(); - } - arg - }) - .collect(); - b.projection_ty.substs = tcx.mk_substs(&substs); - } - - 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())) - }); - // 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)), - ) - .chain(auto_trait_predicates) - .collect::<SmallVec<[_; 8]>>(); - v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder())); - v.dedup(); - let existential_predicates = tcx.mk_poly_existential_predicates(&v); - - // Use explicitly-specified region bound. - let region_bound = if !lifetime.is_elided() { - self.ast_region_to_region(lifetime, None) - } else { - self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| { - if tcx.named_bound_var(lifetime.hir_id).is_some() { - self.ast_region_to_region(lifetime, None) - } else { - self.re_infer(None, span).unwrap_or_else(|| { - let mut err = struct_span_err!( - tcx.sess, - span, - E0228, - "the lifetime bound for this object type cannot be deduced \ - from context; please supply an explicit bound" - ); - let e = if borrowed { - // We will have already emitted an error E0106 complaining about a - // missing named lifetime in `&dyn Trait`, so we elide this one. - err.delay_as_bug() - } else { - err.emit() - }; - ty::Region::new_error(tcx, e) - }) - } - }) - }; - debug!("region_bound: {:?}", region_bound); - - let ty = tcx.mk_dynamic(existential_predicates, region_bound, representation); - debug!("trait_object_type: {:?}", ty); - ty - } - fn report_ambiguous_associated_type( &self, span: Span, @@ -1970,7 +1588,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { assert!(!ct.ty().has_escaping_bound_vars()); match ct.kind() { - ty::ConstKind::Bound(_, bv) => self.tcx.mk_const( + ty::ConstKind::Bound(_, bv) => ty::Const::new_placeholder( + self.tcx, ty::PlaceholderConst { universe: self.universe, bound: bv }, ct.ty(), ), @@ -2801,7 +2420,14 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { TraitObjectSyntax::DynStar => ty::DynStar, }; - self.conv_object_ty_poly_trait_ref(ast_ty.span, bounds, lifetime, borrowed, repr) + self.conv_object_ty_poly_trait_ref( + ast_ty.span, + ast_ty.hir_id, + bounds, + lifetime, + borrowed, + repr, + ) } hir::TyKind::Path(hir::QPath::Resolved(maybe_qself, path)) => { debug!(?maybe_qself, ?path); diff --git a/compiler/rustc_hir_analysis/src/astconv/object_safety.rs b/compiler/rustc_hir_analysis/src/astconv/object_safety.rs new file mode 100644 index 00000000000..918724e0477 --- /dev/null +++ b/compiler/rustc_hir_analysis/src/astconv/object_safety.rs @@ -0,0 +1,408 @@ +use crate::astconv::{GenericArgCountMismatch, GenericArgCountResult, OnlySelfBounds}; +use crate::bounds::Bounds; +use crate::errors::TraitObjectDeclaredWithNoTraits; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_errors::struct_span_err; +use rustc_hir as hir; +use rustc_hir::def::{DefKind, Res}; +use rustc_hir::def_id::DefId; +use rustc_lint_defs::builtin::UNUSED_ASSOCIATED_TYPE_BOUNDS; +use rustc_middle::ty::{self, Ty}; +use rustc_middle::ty::{DynKind, ToPredicate}; +use rustc_span::Span; +use rustc_trait_selection::traits::error_reporting::report_object_safety_error; +use rustc_trait_selection::traits::{self, astconv_object_safety_violations}; + +use smallvec::{smallvec, SmallVec}; +use std::collections::BTreeSet; + +use super::AstConv; + +impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { + pub(super) fn conv_object_ty_poly_trait_ref( + &self, + span: Span, + hir_id: hir::HirId, + hir_trait_bounds: &[hir::PolyTraitRef<'_>], + lifetime: &hir::Lifetime, + borrowed: bool, + representation: DynKind, + ) -> Ty<'tcx> { + let tcx = self.tcx(); + + let mut 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() { + if let GenericArgCountResult { + correct: + Err(GenericArgCountMismatch { invalid_args: cur_potential_assoc_types, .. }), + .. + } = self.instantiate_poly_trait_ref( + &trait_bound.trait_ref, + trait_bound.span, + ty::BoundConstness::NotConst, + ty::ImplPolarity::Positive, + dummy_self, + &mut bounds, + false, + // FIXME: This should be `true`, but we don't really handle + // associated type bounds or type aliases in objects in a way + // that makes this meaningful, I think. + OnlySelfBounds(false), + ) { + 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::ImplPolarity::Positive); + trait_bounds.push(( + bound_pred.rebind(trait_pred.trait_ref), + span, + trait_pred.constness, + )); + } + 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(_) => { + bug!() + } + } + } + + // 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 + .filter(|i| i.trait_ref().self_ty().skip_binder() == dummy_self) + .partition(|i| tcx.trait_is_auto(i.trait_ref().def_id())); + if regular_traits.len() > 1 { + let first_trait = ®ular_traits[0]; + let additional_trait = ®ular_traits[1]; + let mut err = struct_span_err!( + tcx.sess, + additional_trait.bottom().1, + 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.help(format!( + "consider creating a new trait with all of these as supertraits and using that \ + trait here instead: `trait NewTrait: {} {{}}`", + regular_traits + .iter() + .map(|t| t.trait_ref().print_only_trait_path().to_string()) + .collect::<Vec<_>>() + .join(" + "), + )); + err.note( + "auto-traits like `Send` and `Sync` are traits that have special properties; \ + for more information on them, visit \ + <https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits>", + ); + err.emit(); + } + + if regular_traits.is_empty() && auto_traits.is_empty() { + 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 reported = + tcx.sess.emit_err(TraitObjectDeclaredWithNoTraits { span, trait_alias_span }); + return tcx.ty_error(reported); + } + + // Check that there are no gross object safety violations; + // most importantly, that the supertraits don't contain `Self`, + // to avoid ICEs. + for item in ®ular_traits { + let object_safety_violations = + astconv_object_safety_violations(tcx, item.trait_ref().def_id()); + if !object_safety_violations.is_empty() { + let reported = report_object_safety_error( + tcx, + span, + item.trait_ref().def_id(), + &object_safety_violations, + ) + .emit(); + return tcx.ty_error(reported); + } + } + + // Use a `BTreeSet` to keep output in a more consistent order. + let mut associated_types: FxHashMap<Span, BTreeSet<DefId>> = FxHashMap::default(); + + let regular_traits_refs_spans = trait_bounds + .into_iter() + .filter(|(trait_ref, _, _)| !tcx.trait_is_auto(trait_ref.def_id())); + + for (base_trait_ref, span, constness) in regular_traits_refs_spans { + assert_eq!(constness, ty::BoundConstness::NotConst); + let base_pred: ty::Predicate<'tcx> = base_trait_ref.to_predicate(tcx); + for pred in traits::elaborate(tcx, [base_pred]) { + debug!("conv_object_ty_poly_trait_ref: observing object predicate `{:?}`", pred); + + let bound_predicate = pred.kind(); + match bound_predicate.skip_binder() { + ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) => { + let pred = bound_predicate.rebind(pred); + associated_types.entry(span).or_default().extend( + tcx.associated_items(pred.def_id()) + .in_definition_order() + .filter(|item| item.kind == ty::AssocKind::Type) + .filter(|item| item.opt_rpitit_info.is_none()) + .map(|item| item.def_id), + ); + } + ty::PredicateKind::Clause(ty::ClauseKind::Projection(pred)) => { + let pred = bound_predicate.rebind(pred); + // A `Self` within the original bound will be substituted with a + // `trait_object_dummy_self`, so check for that. + let references_self = match pred.skip_binder().term.unpack() { + ty::TermKind::Ty(ty) => ty.walk().any(|arg| arg == dummy_self.into()), + ty::TermKind::Const(c) => { + c.ty().walk().any(|arg| arg == dummy_self.into()) + } + }; + + // If the projection output contains `Self`, force the user to + // elaborate it explicitly to avoid a lot of complexity. + // + // The "classically useful" case is the following: + // ``` + // trait MyTrait: FnMut() -> <Self as MyTrait>::MyOutput { + // type MyOutput; + // } + // ``` + // + // Here, the user could theoretically write `dyn MyTrait<Output = X>`, + // but actually supporting that would "expand" to an infinitely-long type + // `fix $ τ → dyn MyTrait<MyOutput = X, Output = <τ as MyTrait>::MyOutput`. + // + // Instead, we force the user to write + // `dyn MyTrait<MyOutput = X, Output = X>`, which is uglier but works. See + // the discussion in #56288 for alternatives. + if !references_self { + // Include projections defined on supertraits. + projection_bounds.push((pred, span)); + } + } + _ => (), + } + } + } + + // `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 def_ids in associated_types.values_mut() { + for (projection_bound, span) in &projection_bounds { + let def_id = projection_bound.projection_def_id(); + def_ids.remove(&def_id); + if tcx.generics_require_sized_self(def_id) { + tcx.emit_spanned_lint( + UNUSED_ASSOCIATED_TYPE_BOUNDS, + hir_id, + *span, + crate::errors::UnusedAssociatedTypeBounds { span: *span }, + ); + } + } + // If the associated type has a `where Self: Sized` bound, we do not need to constrain the associated + // type in the `dyn Trait`. + def_ids.retain(|def_id| !tcx.generics_require_sized_self(def_id)); + } + + self.complain_about_missing_associated_types( + associated_types, + potential_assoc_types, + hir_trait_bounds, + ); + + // De-duplicate auto traits so that, e.g., `dyn Trait + Send + Send` is the same as + // `dyn Trait + Send`. + // 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: {:?}", regular_traits); + debug!("auto_traits: {:?}", 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>| { + assert_eq!(trait_ref.self_ty(), dummy_self); + + // 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 substs: Vec<_> = trait_ref + .substs + .iter() + .enumerate() + .skip(1) // Remove `Self` for `ExistentialPredicate`. + .map(|(index, arg)| { + if arg == dummy_self.into() { + let param = &generics.params[index]; + missing_type_params.push(param.name); + return tcx.ty_error_misc().into(); + } else if arg.walk().any(|arg| arg == dummy_self.into()) { + references_self = true; + return tcx.ty_error_misc().into(); + } + arg + }) + .collect(); + let substs = tcx.mk_substs(&substs); + + let span = i.bottom().1; + let empty_generic_args = hir_trait_bounds.iter().any(|hir_bound| { + hir_bound.trait_ref.path.res == Res::Def(DefKind::Trait, trait_ref.def_id) + && hir_bound.span.contains(span) + }); + self.complain_about_missing_type_params( + missing_type_params, + trait_ref.def_id, + span, + empty_generic_args, + ); + + if references_self { + let def_id = i.bottom().0.def_id(); + let mut err = struct_span_err!( + tcx.sess, + i.bottom().1, + E0038, + "the {} `{}` cannot be made into an object", + tcx.def_descr(def_id), + tcx.item_name(def_id), + ); + err.note( + rustc_middle::traits::ObjectSafetyViolation::SupertraitSelf(smallvec![]) + .error_msg(), + ); + err.emit(); + } + + ty::ExistentialTraitRef { def_id: trait_ref.def_id, substs } + }) + }); + + let existential_projections = projection_bounds + .iter() + // We filter out traits that don't have `Self` as their self type above, + // we need to do the same for projections. + .filter(|(bound, _)| bound.skip_binder().self_ty() == dummy_self) + .map(|(bound, _)| { + bound.map_bound(|mut b| { + assert_eq!(b.projection_ty.self_ty(), dummy_self); + + // Like for trait refs, verify that `dummy_self` did not leak inside default type + // parameters. + let references_self = b.projection_ty.substs.iter().skip(1).any(|arg| { + if arg.walk().any(|arg| arg == dummy_self.into()) { + return true; + } + false + }); + if references_self { + let guar = tcx.sess.delay_span_bug( + span, + "trait object projection bounds reference `Self`", + ); + let substs: Vec<_> = b + .projection_ty + .substs + .iter() + .map(|arg| { + if arg.walk().any(|arg| arg == dummy_self.into()) { + return tcx.ty_error(guar).into(); + } + arg + }) + .collect(); + b.projection_ty.substs = tcx.mk_substs(&substs); + } + + 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())) + }); + // 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)), + ) + .chain(auto_trait_predicates) + .collect::<SmallVec<[_; 8]>>(); + v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder())); + v.dedup(); + let existential_predicates = tcx.mk_poly_existential_predicates(&v); + + // Use explicitly-specified region bound. + let region_bound = if !lifetime.is_elided() { + self.ast_region_to_region(lifetime, None) + } else { + self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| { + if tcx.named_bound_var(lifetime.hir_id).is_some() { + self.ast_region_to_region(lifetime, None) + } else { + self.re_infer(None, span).unwrap_or_else(|| { + let mut err = struct_span_err!( + tcx.sess, + span, + E0228, + "the lifetime bound for this object type cannot be deduced \ + from context; please supply an explicit bound" + ); + let e = if borrowed { + // We will have already emitted an error E0106 complaining about a + // missing named lifetime in `&dyn Trait`, so we elide this one. + err.delay_as_bug() + } else { + err.emit() + }; + ty::Region::new_error(tcx, e) + }) + } + }) + }; + debug!("region_bound: {:?}", region_bound); + + let ty = tcx.mk_dynamic(existential_predicates, region_bound, representation); + debug!("trait_object_type: {:?}", ty); + ty + } +} 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 3f5164e093d..0fa65eff616 100644 --- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs +++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs @@ -2047,11 +2047,10 @@ pub(super) fn check_type_bounds<'tcx>( GenericParamDefKind::Const { .. } => { let bound_var = ty::BoundVariableKind::Const; bound_vars.push(bound_var); - tcx.mk_const( - ty::ConstKind::Bound( - ty::INNERMOST, - ty::BoundVar::from_usize(bound_vars.len() - 1), - ), + ty::Const::new_bound( + tcx, + ty::INNERMOST, + ty::BoundVar::from_usize(bound_vars.len() - 1), tcx.type_of(param.def_id) .no_bound_vars() .expect("const parameter types cannot be generic"), diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index d7ac9e7ce73..0339e79a278 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -390,7 +390,7 @@ impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> { // left alone. r => bug!("unexpected region: {r:?}"), }); - self.tcx().const_error_with_message(ty, span, "bad placeholder constant") + ty::Const::new_error_with_message(self.tcx(), ty, span, "bad placeholder constant") } fn projected_ty_from_poly_trait_ref( diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs index 1d00dc2a11d..df2c24a6001 100644 --- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs @@ -243,9 +243,12 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen let name = param.name.ident().name; let param_const = ty::ParamConst::new(index, name); - let ct_ty = tcx.type_of(param.def_id.to_def_id()).subst_identity(); + let ct_ty = tcx + .type_of(param.def_id.to_def_id()) + .no_bound_vars() + .expect("const parameters cannot be generic"); - let ct = tcx.mk_const(param_const, ct_ty); + let ct = ty::Const::new_param(tcx, param_const, ct_ty); predicates.insert(( ty::ClauseKind::ConstArgHasType(ct, ct_ty).to_predicate(tcx), diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs index cb840592edd..205e26d0eda 100644 --- a/compiler/rustc_hir_analysis/src/errors.rs +++ b/compiler/rustc_hir_analysis/src/errors.rs @@ -5,7 +5,7 @@ use rustc_errors::{ error_code, Applicability, DiagnosticBuilder, ErrorGuaranteed, Handler, IntoDiagnostic, MultiSpan, }; -use rustc_macros::{Diagnostic, Subdiagnostic}; +use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic}; use rustc_middle::ty::{self, print::TraitRefPrintOnlyTraitPath, Ty}; use rustc_span::{symbol::Ident, Span, Symbol}; @@ -900,3 +900,11 @@ pub(crate) enum LateBoundInApit { param_span: Span, }, } + +#[derive(LintDiagnostic)] +#[diag(hir_analysis_unused_associated_type_bounds)] +#[note] +pub struct UnusedAssociatedTypeBounds { + #[suggestion(code = "")] + pub span: Span, +} |