diff options
Diffstat (limited to 'compiler/rustc_hir_analysis/src')
| -rw-r--r-- | compiler/rustc_hir_analysis/src/collect/dump.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs (renamed from compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs) | 558 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs | 533 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs | 19 | ||||
| -rw-r--r-- | compiler/rustc_hir_analysis/src/variance/constraints.rs | 2 |
6 files changed, 555 insertions, 561 deletions
diff --git a/compiler/rustc_hir_analysis/src/collect/dump.rs b/compiler/rustc_hir_analysis/src/collect/dump.rs index c3f965d8456..44cc2dec1cb 100644 --- a/compiler/rustc_hir_analysis/src/collect/dump.rs +++ b/compiler/rustc_hir_analysis/src/collect/dump.rs @@ -152,7 +152,7 @@ pub(crate) fn vtables<'tcx>(tcx: TyCtxt<'tcx>) { ); continue; }; - let ty::Dynamic(data, _, _) = *ty.kind() else { + let ty::Dynamic(data, _) = *ty.kind() else { tcx.dcx() .span_err(attr.span(), "`rustc_dump_vtable` to type alias of dyn type"); continue; diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs index 76bb59e3f09..c248cd7fec2 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs @@ -1,16 +1,22 @@ +use rustc_ast::TraitObjectSyntax; use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet}; use rustc_errors::codes::*; -use rustc_errors::struct_span_code_err; +use rustc_errors::{ + Applicability, Diag, EmissionGuarantee, StashKey, Suggestions, 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_hir::def_id::DefId; +use rustc_lint_defs::builtin::{BARE_TRAIT_OBJECTS, UNUSED_ASSOCIATED_TYPE_BOUNDS}; use rustc_middle::ty::elaborate::ClauseWithSupertraitSpan; use rustc_middle::ty::{ - self, BottomUpFolder, DynKind, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable, + self, BottomUpFolder, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, Upcast, }; +use rustc_span::edit_distance::find_best_match_for_name; use rustc_span::{ErrorGuaranteed, Span}; use rustc_trait_selection::error_reporting::traits::report_dyn_incompatibility; +use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName; use rustc_trait_selection::traits; use smallvec::{SmallVec, smallvec}; use tracing::{debug, instrument}; @@ -28,11 +34,24 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { hir_id: hir::HirId, hir_bounds: &[hir::PolyTraitRef<'tcx>], lifetime: &hir::Lifetime, - representation: DynKind, + syntax: TraitObjectSyntax, ) -> Ty<'tcx> { let tcx = self.tcx(); let dummy_self = tcx.types.trait_object_dummy_self; + match syntax { + TraitObjectSyntax::Dyn => {} + TraitObjectSyntax::None => { + match self.prohibit_or_lint_bare_trait_object_ty(span, hir_id, hir_bounds) { + // Don't continue with type analysis if the `dyn` keyword is missing. + // It generates confusing errors, especially if the user meant to use + // another keyword like `impl`. + Some(guar) => return Ty::new_error(tcx, guar), + None => {} + } + } + } + let mut user_written_bounds = Vec::new(); let mut potential_assoc_types = Vec::new(); for poly_trait_ref in hir_bounds.iter() { @@ -47,10 +66,16 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { } } - let ast_bounds: Vec<_> = - hir_bounds.iter().map(|&trait_ref| hir::GenericBound::Trait(trait_ref)).collect(); - - self.add_default_traits(&mut user_written_bounds, dummy_self, &ast_bounds, None, span); + self.add_default_traits( + &mut user_written_bounds, + dummy_self, + &hir_bounds + .iter() + .map(|&trait_ref| hir::GenericBound::Trait(trait_ref)) + .collect::<Vec<_>>(), + None, + span, + ); let (elaborated_trait_bounds, elaborated_projection_bounds) = traits::expand_trait_aliases(tcx, user_written_bounds.iter().copied()); @@ -431,7 +456,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { }; debug!(?region_bound); - Ty::new_dynamic(tcx, existential_predicates, region_bound, representation) + Ty::new_dynamic(tcx, existential_predicates, region_bound) } /// Check that elaborating the principal of a trait ref doesn't lead to projections @@ -483,6 +508,521 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { }, ); } + + /// Prohibit or lint against *bare* trait object types depending on the edition. + /// + /// *Bare* trait object types are ones that aren't preceded by the keyword `dyn`. + /// In edition 2021 and onward we emit a hard error for them. + fn prohibit_or_lint_bare_trait_object_ty( + &self, + span: Span, + hir_id: hir::HirId, + hir_bounds: &[hir::PolyTraitRef<'tcx>], + ) -> Option<ErrorGuaranteed> { + let tcx = self.tcx(); + let [poly_trait_ref, ..] = hir_bounds else { return None }; + + let in_path = match tcx.parent_hir_node(hir_id) { + hir::Node::Ty(hir::Ty { + kind: hir::TyKind::Path(hir::QPath::TypeRelative(qself, _)), + .. + }) + | hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Path(hir::QPath::TypeRelative(qself, _)), + .. + }) + | hir::Node::PatExpr(hir::PatExpr { + kind: hir::PatExprKind::Path(hir::QPath::TypeRelative(qself, _)), + .. + }) if qself.hir_id == hir_id => true, + _ => false, + }; + let needs_bracket = in_path + && !tcx + .sess + .source_map() + .span_to_prev_source(span) + .ok() + .is_some_and(|s| s.trim_end().ends_with('<')); + + let is_global = poly_trait_ref.trait_ref.path.is_global(); + + let mut sugg = vec![( + span.shrink_to_lo(), + format!( + "{}dyn {}", + if needs_bracket { "<" } else { "" }, + if is_global { "(" } else { "" }, + ), + )]; + + if is_global || needs_bracket { + sugg.push(( + span.shrink_to_hi(), + format!( + "{}{}", + if is_global { ")" } else { "" }, + if needs_bracket { ">" } else { "" }, + ), + )); + } + + if span.edition().at_least_rust_2021() { + let mut diag = rustc_errors::struct_span_code_err!( + self.dcx(), + span, + E0782, + "{}", + "expected a type, found a trait" + ); + if span.can_be_used_for_suggestions() + && poly_trait_ref.trait_ref.trait_def_id().is_some() + && !self.maybe_suggest_impl_trait(span, hir_id, hir_bounds, &mut diag) + && !self.maybe_suggest_dyn_trait(hir_id, sugg, &mut diag) + { + self.maybe_suggest_add_generic_impl_trait(span, hir_id, &mut diag); + } + // Check if the impl trait that we are considering is an impl of a local trait. + self.maybe_suggest_blanket_trait_impl(span, hir_id, &mut diag); + self.maybe_suggest_assoc_ty_bound(hir_id, &mut diag); + self.maybe_suggest_typoed_method( + hir_id, + poly_trait_ref.trait_ref.trait_def_id(), + &mut diag, + ); + // In case there is an associated type with the same name + // Add the suggestion to this error + if let Some(mut sugg) = + self.dcx().steal_non_err(span, StashKey::AssociatedTypeSuggestion) + && let Suggestions::Enabled(ref mut s1) = diag.suggestions + && let Suggestions::Enabled(ref mut s2) = sugg.suggestions + { + s1.append(s2); + sugg.cancel(); + } + Some(diag.emit()) + } else { + tcx.node_span_lint(BARE_TRAIT_OBJECTS, hir_id, span, |lint| { + lint.primary_message("trait objects without an explicit `dyn` are deprecated"); + if span.can_be_used_for_suggestions() { + lint.multipart_suggestion_verbose( + "if this is a dyn-compatible trait, use `dyn`", + sugg, + Applicability::MachineApplicable, + ); + } + self.maybe_suggest_blanket_trait_impl(span, hir_id, lint); + }); + None + } + } + + /// For a struct or enum with an invalid bare trait object field, suggest turning + /// it into a generic type bound. + fn maybe_suggest_add_generic_impl_trait( + &self, + span: Span, + hir_id: hir::HirId, + diag: &mut Diag<'_>, + ) -> bool { + let tcx = self.tcx(); + + let parent_hir_id = tcx.parent_hir_id(hir_id); + let parent_item = tcx.hir_get_parent_item(hir_id).def_id; + + let generics = match tcx.hir_node_by_def_id(parent_item) { + hir::Node::Item(hir::Item { + kind: hir::ItemKind::Struct(_, generics, variant), + .. + }) => { + if !variant.fields().iter().any(|field| field.hir_id == parent_hir_id) { + return false; + } + generics + } + hir::Node::Item(hir::Item { kind: hir::ItemKind::Enum(_, generics, def), .. }) => { + if !def + .variants + .iter() + .flat_map(|variant| variant.data.fields().iter()) + .any(|field| field.hir_id == parent_hir_id) + { + return false; + } + generics + } + _ => return false, + }; + + let Ok(rendered_ty) = tcx.sess.source_map().span_to_snippet(span) else { + return false; + }; + + let param = "TUV" + .chars() + .map(|c| c.to_string()) + .chain((0..).map(|i| format!("P{i}"))) + .find(|s| !generics.params.iter().any(|param| param.name.ident().as_str() == s)) + .expect("we definitely can find at least one param name to generate"); + let mut sugg = vec![(span, param.to_string())]; + if let Some(insertion_span) = generics.span_for_param_suggestion() { + sugg.push((insertion_span, format!(", {param}: {}", rendered_ty))); + } else { + sugg.push((generics.where_clause_span, format!("<{param}: {}>", rendered_ty))); + } + diag.multipart_suggestion_verbose( + "you might be missing a type parameter", + sugg, + Applicability::MachineApplicable, + ); + true + } + + /// Make sure that we are in the condition to suggest the blanket implementation. + fn maybe_suggest_blanket_trait_impl<G: EmissionGuarantee>( + &self, + span: Span, + hir_id: hir::HirId, + diag: &mut Diag<'_, G>, + ) { + let tcx = self.tcx(); + let parent_id = tcx.hir_get_parent_item(hir_id).def_id; + if let hir::Node::Item(hir::Item { + kind: hir::ItemKind::Impl(hir::Impl { self_ty: impl_self_ty, of_trait, generics, .. }), + .. + }) = tcx.hir_node_by_def_id(parent_id) + && hir_id == impl_self_ty.hir_id + { + let Some(of_trait) = of_trait else { + diag.span_suggestion_verbose( + impl_self_ty.span.shrink_to_hi(), + "you might have intended to implement this trait for a given type", + format!(" for /* Type */"), + Applicability::HasPlaceholders, + ); + return; + }; + if !of_trait.trait_ref.trait_def_id().is_some_and(|def_id| def_id.is_local()) { + return; + } + let of_trait_span = of_trait.trait_ref.path.span; + // make sure that we are not calling unwrap to abort during the compilation + let Ok(of_trait_name) = tcx.sess.source_map().span_to_snippet(of_trait_span) else { + return; + }; + + let Ok(impl_trait_name) = self.tcx().sess.source_map().span_to_snippet(span) else { + return; + }; + let sugg = self.add_generic_param_suggestion(generics, span, &impl_trait_name); + diag.multipart_suggestion( + format!( + "alternatively use a blanket implementation to implement `{of_trait_name}` for \ + all types that also implement `{impl_trait_name}`" + ), + sugg, + Applicability::MaybeIncorrect, + ); + } + } + + /// Try our best to approximate when adding `dyn` would be helpful for a bare + /// trait object. + /// + /// Right now, this is if the type is either directly nested in another ty, + /// or if it's in the tail field within a struct. This approximates what the + /// user would've gotten on edition 2015, except for the case where we have + /// an *obvious* knock-on `Sized` error. + fn maybe_suggest_dyn_trait( + &self, + hir_id: hir::HirId, + sugg: Vec<(Span, String)>, + diag: &mut Diag<'_>, + ) -> bool { + let tcx = self.tcx(); + + // Look at the direct HIR parent, since we care about the relationship between + // the type and the thing that directly encloses it. + match tcx.parent_hir_node(hir_id) { + // These are all generally ok. Namely, when a trait object is nested + // into another expression or ty, it's either very certain that they + // missed the ty (e.g. `&Trait`) or it's not really possible to tell + // what their intention is, so let's not give confusing suggestions and + // just mention `dyn`. The user can make up their mind what to do here. + hir::Node::Ty(_) + | hir::Node::Expr(_) + | hir::Node::PatExpr(_) + | hir::Node::PathSegment(_) + | hir::Node::AssocItemConstraint(_) + | hir::Node::TraitRef(_) + | hir::Node::Item(_) + | hir::Node::WherePredicate(_) => {} + + hir::Node::Field(field) => { + // Enums can't have unsized fields, fields can only have an unsized tail field. + if let hir::Node::Item(hir::Item { + kind: hir::ItemKind::Struct(_, _, variant), .. + }) = tcx.parent_hir_node(field.hir_id) + && variant + .fields() + .last() + .is_some_and(|tail_field| tail_field.hir_id == field.hir_id) + { + // Ok + } else { + return false; + } + } + _ => return false, + } + + // FIXME: Only emit this suggestion if the trait is dyn-compatible. + diag.multipart_suggestion_verbose( + "you can add the `dyn` keyword if you want a trait object", + sugg, + Applicability::MachineApplicable, + ); + true + } + + fn add_generic_param_suggestion( + &self, + generics: &hir::Generics<'_>, + self_ty_span: Span, + impl_trait_name: &str, + ) -> Vec<(Span, String)> { + // check if the trait has generics, to make a correct suggestion + let param_name = generics.params.next_type_param_name(None); + + let add_generic_sugg = if let Some(span) = generics.span_for_param_suggestion() { + (span, format!(", {param_name}: {impl_trait_name}")) + } else { + (generics.span, format!("<{param_name}: {impl_trait_name}>")) + }; + vec![(self_ty_span, param_name), add_generic_sugg] + } + + /// Make sure that we are in the condition to suggest `impl Trait`. + fn maybe_suggest_impl_trait( + &self, + span: Span, + hir_id: hir::HirId, + hir_bounds: &[hir::PolyTraitRef<'tcx>], + diag: &mut Diag<'_>, + ) -> bool { + let tcx = self.tcx(); + let parent_id = tcx.hir_get_parent_item(hir_id).def_id; + // FIXME: If `type_alias_impl_trait` is enabled, also look for `Trait0<Ty = Trait1>` + // and suggest `Trait0<Ty = impl Trait1>`. + // Functions are found in three different contexts. + // 1. Independent functions + // 2. Functions inside trait blocks + // 3. Functions inside impl blocks + let (sig, generics) = match tcx.hir_node_by_def_id(parent_id) { + hir::Node::Item(hir::Item { + kind: hir::ItemKind::Fn { sig, generics, .. }, .. + }) => (sig, generics), + hir::Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(sig, _), + generics, + .. + }) => (sig, generics), + hir::Node::ImplItem(hir::ImplItem { + kind: hir::ImplItemKind::Fn(sig, _), + generics, + .. + }) => (sig, generics), + _ => return false, + }; + let Ok(trait_name) = tcx.sess.source_map().span_to_snippet(span) else { + return false; + }; + let impl_sugg = vec![(span.shrink_to_lo(), "impl ".to_string())]; + // Check if trait object is safe for suggesting dynamic dispatch. + let is_dyn_compatible = hir_bounds.iter().all(|bound| match bound.trait_ref.path.res { + Res::Def(DefKind::Trait, id) => tcx.is_dyn_compatible(id), + _ => false, + }); + + let borrowed = matches!( + tcx.parent_hir_node(hir_id), + hir::Node::Ty(hir::Ty { kind: hir::TyKind::Ref(..), .. }) + ); + + // Suggestions for function return type. + if let hir::FnRetTy::Return(ty) = sig.decl.output + && ty.peel_refs().hir_id == hir_id + { + let pre = if !is_dyn_compatible { + format!("`{trait_name}` is dyn-incompatible, ") + } else { + String::new() + }; + let msg = format!( + "{pre}use `impl {trait_name}` to return an opaque type, as long as you return a \ + single underlying type", + ); + + diag.multipart_suggestion_verbose(msg, impl_sugg, Applicability::MachineApplicable); + + // Suggest `Box<dyn Trait>` for return type + if is_dyn_compatible { + // If the return type is `&Trait`, we don't want + // the ampersand to be displayed in the `Box<dyn Trait>` + // suggestion. + let suggestion = if borrowed { + vec![(ty.span, format!("Box<dyn {trait_name}>"))] + } else { + vec![ + (ty.span.shrink_to_lo(), "Box<dyn ".to_string()), + (ty.span.shrink_to_hi(), ">".to_string()), + ] + }; + + diag.multipart_suggestion_verbose( + "alternatively, you can return an owned trait object", + suggestion, + Applicability::MachineApplicable, + ); + } + return true; + } + + // Suggestions for function parameters. + for ty in sig.decl.inputs { + if ty.peel_refs().hir_id != hir_id { + continue; + } + let sugg = self.add_generic_param_suggestion(generics, span, &trait_name); + diag.multipart_suggestion_verbose( + format!("use a new generic type parameter, constrained by `{trait_name}`"), + sugg, + Applicability::MachineApplicable, + ); + diag.multipart_suggestion_verbose( + "you can also use an opaque type, but users won't be able to specify the type \ + parameter when calling the `fn`, having to rely exclusively on type inference", + impl_sugg, + Applicability::MachineApplicable, + ); + if !is_dyn_compatible { + diag.note(format!( + "`{trait_name}` is dyn-incompatible, otherwise a trait object could be used" + )); + } else { + // No ampersand in suggestion if it's borrowed already + let (dyn_str, paren_dyn_str) = + if borrowed { ("dyn ", "(dyn ") } else { ("&dyn ", "&(dyn ") }; + + let sugg = if let [_, _, ..] = hir_bounds { + // There is more than one trait bound, we need surrounding parentheses. + vec![ + (span.shrink_to_lo(), paren_dyn_str.to_string()), + (span.shrink_to_hi(), ")".to_string()), + ] + } else { + vec![(span.shrink_to_lo(), dyn_str.to_string())] + }; + diag.multipart_suggestion_verbose( + format!( + "alternatively, use a trait object to accept any type that implements \ + `{trait_name}`, accessing its methods at runtime using dynamic dispatch", + ), + sugg, + Applicability::MachineApplicable, + ); + } + return true; + } + false + } + + fn maybe_suggest_assoc_ty_bound(&self, hir_id: hir::HirId, diag: &mut Diag<'_>) { + let mut parents = self.tcx().hir_parent_iter(hir_id); + + if let Some((c_hir_id, hir::Node::AssocItemConstraint(constraint))) = parents.next() + && let Some(obj_ty) = constraint.ty() + && let Some((_, hir::Node::TraitRef(trait_ref))) = parents.next() + { + if let Some((_, hir::Node::Ty(ty))) = parents.next() + && let hir::TyKind::TraitObject(..) = ty.kind + { + // Assoc ty bounds aren't permitted inside trait object types. + return; + } + + if trait_ref + .path + .segments + .iter() + .find_map(|seg| { + seg.args.filter(|args| args.constraints.iter().any(|c| c.hir_id == c_hir_id)) + }) + .is_none_or(|args| args.parenthesized != hir::GenericArgsParentheses::No) + { + // Only consider angle-bracketed args (where we have a `=` to replace with `:`). + return; + } + + let lo = if constraint.gen_args.span_ext.is_dummy() { + constraint.ident.span + } else { + constraint.gen_args.span_ext + }; + let hi = obj_ty.span; + + if !lo.eq_ctxt(hi) { + return; + } + + diag.span_suggestion_verbose( + lo.between(hi), + "you might have meant to write a bound here", + ": ", + Applicability::MaybeIncorrect, + ); + } + } + + fn maybe_suggest_typoed_method( + &self, + hir_id: hir::HirId, + trait_def_id: Option<DefId>, + diag: &mut Diag<'_>, + ) { + let tcx = self.tcx(); + let Some(trait_def_id) = trait_def_id else { + return; + }; + let hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Path(hir::QPath::TypeRelative(path_ty, segment)), + .. + }) = tcx.parent_hir_node(hir_id) + else { + return; + }; + if path_ty.hir_id != hir_id { + return; + } + let names: Vec<_> = tcx + .associated_items(trait_def_id) + .in_definition_order() + .filter(|assoc| assoc.namespace() == hir::def::Namespace::ValueNS) + .map(|cand| cand.name()) + .collect(); + if let Some(typo) = find_best_match_for_name(&names, segment.ident.name, None) { + diag.span_suggestion_verbose( + segment.ident.span, + format!( + "you may have misspelled this associated item, causing `{}` \ + to be interpreted as a type rather than a trait", + tcx.item_name(trait_def_id), + ), + typo, + Applicability::MaybeIncorrect, + ); + } + } } fn replace_dummy_self_with_error<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>( 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 0cf9cb7193f..16505174464 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs @@ -859,7 +859,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { bound_spans.get_mut_or_insert_default(tcx.def_span(def.did())).push(msg) } // Point at the trait object that couldn't satisfy the bound. - ty::Dynamic(preds, _, _) => { + ty::Dynamic(preds, _) => { for pred in preds.iter() { match pred.skip_binder() { ty::ExistentialPredicate::Trait(tr) => { diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs deleted file mode 100644 index 56998b5b53c..00000000000 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs +++ /dev/null @@ -1,533 +0,0 @@ -use rustc_ast::TraitObjectSyntax; -use rustc_errors::codes::*; -use rustc_errors::{Diag, EmissionGuarantee, ErrorGuaranteed, StashKey, Suggestions}; -use rustc_hir as hir; -use rustc_hir::def::{DefKind, Namespace, Res}; -use rustc_hir::def_id::DefId; -use rustc_lint_defs::Applicability; -use rustc_lint_defs::builtin::BARE_TRAIT_OBJECTS; -use rustc_span::Span; -use rustc_span::edit_distance::find_best_match_for_name; -use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName; - -use super::HirTyLowerer; - -impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { - /// Prohibit or lint against *bare* trait object types depending on the edition. - /// - /// *Bare* trait object types are ones that aren't preceded by the keyword `dyn`. - /// In edition 2021 and onward we emit a hard error for them. - pub(super) fn prohibit_or_lint_bare_trait_object_ty( - &self, - self_ty: &hir::Ty<'_>, - ) -> Option<ErrorGuaranteed> { - let tcx = self.tcx(); - - let poly_trait_ref = if let hir::TyKind::TraitObject([poly_trait_ref, ..], tagged_ptr) = - self_ty.kind - && let TraitObjectSyntax::None = tagged_ptr.tag() - { - poly_trait_ref - } else { - return None; - }; - - let in_path = match tcx.parent_hir_node(self_ty.hir_id) { - hir::Node::Ty(hir::Ty { - kind: hir::TyKind::Path(hir::QPath::TypeRelative(qself, _)), - .. - }) - | hir::Node::Expr(hir::Expr { - kind: hir::ExprKind::Path(hir::QPath::TypeRelative(qself, _)), - .. - }) - | hir::Node::PatExpr(hir::PatExpr { - kind: hir::PatExprKind::Path(hir::QPath::TypeRelative(qself, _)), - .. - }) if qself.hir_id == self_ty.hir_id => true, - _ => false, - }; - let needs_bracket = in_path - && !tcx - .sess - .source_map() - .span_to_prev_source(self_ty.span) - .ok() - .is_some_and(|s| s.trim_end().ends_with('<')); - - let is_global = poly_trait_ref.trait_ref.path.is_global(); - - let mut sugg = vec![( - self_ty.span.shrink_to_lo(), - format!( - "{}dyn {}", - if needs_bracket { "<" } else { "" }, - if is_global { "(" } else { "" }, - ), - )]; - - if is_global || needs_bracket { - sugg.push(( - self_ty.span.shrink_to_hi(), - format!( - "{}{}", - if is_global { ")" } else { "" }, - if needs_bracket { ">" } else { "" }, - ), - )); - } - - if self_ty.span.edition().at_least_rust_2021() { - let mut diag = rustc_errors::struct_span_code_err!( - self.dcx(), - self_ty.span, - E0782, - "{}", - "expected a type, found a trait" - ); - if self_ty.span.can_be_used_for_suggestions() - && poly_trait_ref.trait_ref.trait_def_id().is_some() - && !self.maybe_suggest_impl_trait(self_ty, &mut diag) - && !self.maybe_suggest_dyn_trait(self_ty, sugg, &mut diag) - { - self.maybe_suggest_add_generic_impl_trait(self_ty, &mut diag); - } - // Check if the impl trait that we are considering is an impl of a local trait. - self.maybe_suggest_blanket_trait_impl(self_ty, &mut diag); - self.maybe_suggest_assoc_ty_bound(self_ty, &mut diag); - self.maybe_suggest_typoed_method( - self_ty, - poly_trait_ref.trait_ref.trait_def_id(), - &mut diag, - ); - // In case there is an associated type with the same name - // Add the suggestion to this error - if let Some(mut sugg) = - self.dcx().steal_non_err(self_ty.span, StashKey::AssociatedTypeSuggestion) - && let Suggestions::Enabled(ref mut s1) = diag.suggestions - && let Suggestions::Enabled(ref mut s2) = sugg.suggestions - { - s1.append(s2); - sugg.cancel(); - } - Some(diag.emit()) - } else { - tcx.node_span_lint(BARE_TRAIT_OBJECTS, self_ty.hir_id, self_ty.span, |lint| { - lint.primary_message("trait objects without an explicit `dyn` are deprecated"); - if self_ty.span.can_be_used_for_suggestions() { - lint.multipart_suggestion_verbose( - "if this is a dyn-compatible trait, use `dyn`", - sugg, - Applicability::MachineApplicable, - ); - } - self.maybe_suggest_blanket_trait_impl(self_ty, lint); - }); - None - } - } - - /// For a struct or enum with an invalid bare trait object field, suggest turning - /// it into a generic type bound. - fn maybe_suggest_add_generic_impl_trait( - &self, - self_ty: &hir::Ty<'_>, - diag: &mut Diag<'_>, - ) -> bool { - let tcx = self.tcx(); - - let parent_hir_id = tcx.parent_hir_id(self_ty.hir_id); - let parent_item = tcx.hir_get_parent_item(self_ty.hir_id).def_id; - - let generics = match tcx.hir_node_by_def_id(parent_item) { - hir::Node::Item(hir::Item { - kind: hir::ItemKind::Struct(_, generics, variant), - .. - }) => { - if !variant.fields().iter().any(|field| field.hir_id == parent_hir_id) { - return false; - } - generics - } - hir::Node::Item(hir::Item { kind: hir::ItemKind::Enum(_, generics, def), .. }) => { - if !def - .variants - .iter() - .flat_map(|variant| variant.data.fields().iter()) - .any(|field| field.hir_id == parent_hir_id) - { - return false; - } - generics - } - _ => return false, - }; - - let Ok(rendered_ty) = tcx.sess.source_map().span_to_snippet(self_ty.span) else { - return false; - }; - - let param = "TUV" - .chars() - .map(|c| c.to_string()) - .chain((0..).map(|i| format!("P{i}"))) - .find(|s| !generics.params.iter().any(|param| param.name.ident().as_str() == s)) - .expect("we definitely can find at least one param name to generate"); - let mut sugg = vec![(self_ty.span, param.to_string())]; - if let Some(insertion_span) = generics.span_for_param_suggestion() { - sugg.push((insertion_span, format!(", {param}: {}", rendered_ty))); - } else { - sugg.push((generics.where_clause_span, format!("<{param}: {}>", rendered_ty))); - } - diag.multipart_suggestion_verbose( - "you might be missing a type parameter", - sugg, - Applicability::MachineApplicable, - ); - true - } - /// Make sure that we are in the condition to suggest the blanket implementation. - fn maybe_suggest_blanket_trait_impl<G: EmissionGuarantee>( - &self, - self_ty: &hir::Ty<'_>, - diag: &mut Diag<'_, G>, - ) { - let tcx = self.tcx(); - let parent_id = tcx.hir_get_parent_item(self_ty.hir_id).def_id; - if let hir::Node::Item(hir::Item { - kind: hir::ItemKind::Impl(hir::Impl { self_ty: impl_self_ty, of_trait, generics, .. }), - .. - }) = tcx.hir_node_by_def_id(parent_id) - && self_ty.hir_id == impl_self_ty.hir_id - { - let Some(of_trait) = of_trait else { - diag.span_suggestion_verbose( - impl_self_ty.span.shrink_to_hi(), - "you might have intended to implement this trait for a given type", - format!(" for /* Type */"), - Applicability::HasPlaceholders, - ); - return; - }; - if !of_trait.trait_ref.trait_def_id().is_some_and(|def_id| def_id.is_local()) { - return; - } - let of_trait_span = of_trait.trait_ref.path.span; - // make sure that we are not calling unwrap to abort during the compilation - let Ok(of_trait_name) = tcx.sess.source_map().span_to_snippet(of_trait_span) else { - return; - }; - - let Ok(impl_trait_name) = self.tcx().sess.source_map().span_to_snippet(self_ty.span) - else { - return; - }; - let sugg = self.add_generic_param_suggestion(generics, self_ty.span, &impl_trait_name); - diag.multipart_suggestion( - format!( - "alternatively use a blanket implementation to implement `{of_trait_name}` for \ - all types that also implement `{impl_trait_name}`" - ), - sugg, - Applicability::MaybeIncorrect, - ); - } - } - - /// Try our best to approximate when adding `dyn` would be helpful for a bare - /// trait object. - /// - /// Right now, this is if the type is either directly nested in another ty, - /// or if it's in the tail field within a struct. This approximates what the - /// user would've gotten on edition 2015, except for the case where we have - /// an *obvious* knock-on `Sized` error. - fn maybe_suggest_dyn_trait( - &self, - self_ty: &hir::Ty<'_>, - sugg: Vec<(Span, String)>, - diag: &mut Diag<'_>, - ) -> bool { - let tcx = self.tcx(); - - // Look at the direct HIR parent, since we care about the relationship between - // the type and the thing that directly encloses it. - match tcx.parent_hir_node(self_ty.hir_id) { - // These are all generally ok. Namely, when a trait object is nested - // into another expression or ty, it's either very certain that they - // missed the ty (e.g. `&Trait`) or it's not really possible to tell - // what their intention is, so let's not give confusing suggestions and - // just mention `dyn`. The user can make up their mind what to do here. - hir::Node::Ty(_) - | hir::Node::Expr(_) - | hir::Node::PatExpr(_) - | hir::Node::PathSegment(_) - | hir::Node::AssocItemConstraint(_) - | hir::Node::TraitRef(_) - | hir::Node::Item(_) - | hir::Node::WherePredicate(_) => {} - - hir::Node::Field(field) => { - // Enums can't have unsized fields, fields can only have an unsized tail field. - if let hir::Node::Item(hir::Item { - kind: hir::ItemKind::Struct(_, _, variant), .. - }) = tcx.parent_hir_node(field.hir_id) - && variant - .fields() - .last() - .is_some_and(|tail_field| tail_field.hir_id == field.hir_id) - { - // Ok - } else { - return false; - } - } - _ => return false, - } - - // FIXME: Only emit this suggestion if the trait is dyn-compatible. - diag.multipart_suggestion_verbose( - "you can add the `dyn` keyword if you want a trait object", - sugg, - Applicability::MachineApplicable, - ); - true - } - - fn add_generic_param_suggestion( - &self, - generics: &hir::Generics<'_>, - self_ty_span: Span, - impl_trait_name: &str, - ) -> Vec<(Span, String)> { - // check if the trait has generics, to make a correct suggestion - let param_name = generics.params.next_type_param_name(None); - - let add_generic_sugg = if let Some(span) = generics.span_for_param_suggestion() { - (span, format!(", {param_name}: {impl_trait_name}")) - } else { - (generics.span, format!("<{param_name}: {impl_trait_name}>")) - }; - vec![(self_ty_span, param_name), add_generic_sugg] - } - - /// Make sure that we are in the condition to suggest `impl Trait`. - fn maybe_suggest_impl_trait(&self, self_ty: &hir::Ty<'_>, diag: &mut Diag<'_>) -> bool { - let tcx = self.tcx(); - let parent_id = tcx.hir_get_parent_item(self_ty.hir_id).def_id; - // FIXME: If `type_alias_impl_trait` is enabled, also look for `Trait0<Ty = Trait1>` - // and suggest `Trait0<Ty = impl Trait1>`. - // Functions are found in three different contexts. - // 1. Independent functions - // 2. Functions inside trait blocks - // 3. Functions inside impl blocks - let (sig, generics) = match tcx.hir_node_by_def_id(parent_id) { - hir::Node::Item(hir::Item { - kind: hir::ItemKind::Fn { sig, generics, .. }, .. - }) => (sig, generics), - hir::Node::TraitItem(hir::TraitItem { - kind: hir::TraitItemKind::Fn(sig, _), - generics, - .. - }) => (sig, generics), - hir::Node::ImplItem(hir::ImplItem { - kind: hir::ImplItemKind::Fn(sig, _), - generics, - .. - }) => (sig, generics), - _ => return false, - }; - let Ok(trait_name) = tcx.sess.source_map().span_to_snippet(self_ty.span) else { - return false; - }; - let impl_sugg = vec![(self_ty.span.shrink_to_lo(), "impl ".to_string())]; - // Check if trait object is safe for suggesting dynamic dispatch. - let is_dyn_compatible = match self_ty.kind { - hir::TyKind::TraitObject(objects, ..) => { - objects.iter().all(|o| match o.trait_ref.path.res { - Res::Def(DefKind::Trait, id) => tcx.is_dyn_compatible(id), - _ => false, - }) - } - _ => false, - }; - - let borrowed = matches!( - tcx.parent_hir_node(self_ty.hir_id), - hir::Node::Ty(hir::Ty { kind: hir::TyKind::Ref(..), .. }) - ); - - // Suggestions for function return type. - if let hir::FnRetTy::Return(ty) = sig.decl.output - && ty.peel_refs().hir_id == self_ty.hir_id - { - let pre = if !is_dyn_compatible { - format!("`{trait_name}` is dyn-incompatible, ") - } else { - String::new() - }; - let msg = format!( - "{pre}use `impl {trait_name}` to return an opaque type, as long as you return a \ - single underlying type", - ); - - diag.multipart_suggestion_verbose(msg, impl_sugg, Applicability::MachineApplicable); - - // Suggest `Box<dyn Trait>` for return type - if is_dyn_compatible { - // If the return type is `&Trait`, we don't want - // the ampersand to be displayed in the `Box<dyn Trait>` - // suggestion. - let suggestion = if borrowed { - vec![(ty.span, format!("Box<dyn {trait_name}>"))] - } else { - vec![ - (ty.span.shrink_to_lo(), "Box<dyn ".to_string()), - (ty.span.shrink_to_hi(), ">".to_string()), - ] - }; - - diag.multipart_suggestion_verbose( - "alternatively, you can return an owned trait object", - suggestion, - Applicability::MachineApplicable, - ); - } - return true; - } - - // Suggestions for function parameters. - for ty in sig.decl.inputs { - if ty.peel_refs().hir_id != self_ty.hir_id { - continue; - } - let sugg = self.add_generic_param_suggestion(generics, self_ty.span, &trait_name); - diag.multipart_suggestion_verbose( - format!("use a new generic type parameter, constrained by `{trait_name}`"), - sugg, - Applicability::MachineApplicable, - ); - diag.multipart_suggestion_verbose( - "you can also use an opaque type, but users won't be able to specify the type \ - parameter when calling the `fn`, having to rely exclusively on type inference", - impl_sugg, - Applicability::MachineApplicable, - ); - if !is_dyn_compatible { - diag.note(format!( - "`{trait_name}` is dyn-incompatible, otherwise a trait object could be used" - )); - } else { - // No ampersand in suggestion if it's borrowed already - let (dyn_str, paren_dyn_str) = - if borrowed { ("dyn ", "(dyn ") } else { ("&dyn ", "&(dyn ") }; - - let sugg = if let hir::TyKind::TraitObject([_, _, ..], _) = self_ty.kind { - // There is more than one trait bound, we need surrounding parentheses. - vec![ - (self_ty.span.shrink_to_lo(), paren_dyn_str.to_string()), - (self_ty.span.shrink_to_hi(), ")".to_string()), - ] - } else { - vec![(self_ty.span.shrink_to_lo(), dyn_str.to_string())] - }; - diag.multipart_suggestion_verbose( - format!( - "alternatively, use a trait object to accept any type that implements \ - `{trait_name}`, accessing its methods at runtime using dynamic dispatch", - ), - sugg, - Applicability::MachineApplicable, - ); - } - return true; - } - false - } - - fn maybe_suggest_assoc_ty_bound(&self, self_ty: &hir::Ty<'_>, diag: &mut Diag<'_>) { - let mut parents = self.tcx().hir_parent_iter(self_ty.hir_id); - - if let Some((c_hir_id, hir::Node::AssocItemConstraint(constraint))) = parents.next() - && let Some(obj_ty) = constraint.ty() - && let Some((_, hir::Node::TraitRef(trait_ref))) = parents.next() - { - if let Some((_, hir::Node::Ty(ty))) = parents.next() - && let hir::TyKind::TraitObject(..) = ty.kind - { - // Assoc ty bounds aren't permitted inside trait object types. - return; - } - - if trait_ref - .path - .segments - .iter() - .find_map(|seg| { - seg.args.filter(|args| args.constraints.iter().any(|c| c.hir_id == c_hir_id)) - }) - .is_none_or(|args| args.parenthesized != hir::GenericArgsParentheses::No) - { - // Only consider angle-bracketed args (where we have a `=` to replace with `:`). - return; - } - - let lo = if constraint.gen_args.span_ext.is_dummy() { - constraint.ident.span - } else { - constraint.gen_args.span_ext - }; - let hi = obj_ty.span; - - if !lo.eq_ctxt(hi) { - return; - } - - diag.span_suggestion_verbose( - lo.between(hi), - "you might have meant to write a bound here", - ": ", - Applicability::MaybeIncorrect, - ); - } - } - - fn maybe_suggest_typoed_method( - &self, - self_ty: &hir::Ty<'_>, - trait_def_id: Option<DefId>, - diag: &mut Diag<'_>, - ) { - let tcx = self.tcx(); - let Some(trait_def_id) = trait_def_id else { - return; - }; - let hir::Node::Expr(hir::Expr { - kind: hir::ExprKind::Path(hir::QPath::TypeRelative(path_ty, segment)), - .. - }) = tcx.parent_hir_node(self_ty.hir_id) - else { - return; - }; - if path_ty.hir_id != self_ty.hir_id { - return; - } - let names: Vec<_> = tcx - .associated_items(trait_def_id) - .in_definition_order() - .filter(|assoc| assoc.namespace() == Namespace::ValueNS) - .map(|cand| cand.name()) - .collect(); - if let Some(typo) = find_best_match_for_name(&names, segment.ident.name, None) { - diag.span_suggestion_verbose( - segment.ident.span, - format!( - "you may have misspelled this associated item, causing `{}` \ - to be interpreted as a type rather than a trait", - tcx.item_name(trait_def_id), - ), - typo, - Applicability::MaybeIncorrect, - ); - } - } -} 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 c5e079fe89a..9b198d04454 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs @@ -15,15 +15,13 @@ mod bounds; mod cmse; -mod dyn_compatibility; +mod dyn_trait; pub mod errors; pub mod generics; -mod lint; use std::assert_matches::assert_matches; use std::slice; -use rustc_ast::TraitObjectSyntax; use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet}; use rustc_errors::codes::*; use rustc_errors::{ @@ -2428,19 +2426,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { ), hir::TyKind::TraitObject(bounds, tagged_ptr) => { let lifetime = tagged_ptr.pointer(); - let repr = tagged_ptr.tag(); - - if let Some(guar) = self.prohibit_or_lint_bare_trait_object_ty(hir_ty) { - // Don't continue with type analysis if the `dyn` keyword is missing - // It generates confusing errors, especially if the user meant to use another - // keyword like `impl` - Ty::new_error(tcx, guar) - } else { - let repr = match repr { - TraitObjectSyntax::Dyn | TraitObjectSyntax::None => ty::Dyn, - }; - self.lower_trait_object_ty(hir_ty.span, hir_ty.hir_id, bounds, lifetime, repr) - } + let syntax = tagged_ptr.tag(); + self.lower_trait_object_ty(hir_ty.span, hir_ty.hir_id, bounds, lifetime, syntax) } // If we encounter a fully qualified path with RTN generics, then it must have // *not* gone through `lower_ty_maybe_return_type_notation`, and therefore diff --git a/compiler/rustc_hir_analysis/src/variance/constraints.rs b/compiler/rustc_hir_analysis/src/variance/constraints.rs index 960ec7f66ab..be841675821 100644 --- a/compiler/rustc_hir_analysis/src/variance/constraints.rs +++ b/compiler/rustc_hir_analysis/src/variance/constraints.rs @@ -281,7 +281,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> { self.add_constraints_from_args(current, data.def_id, data.args, variance); } - ty::Dynamic(data, r, _) => { + ty::Dynamic(data, r) => { // The type `dyn Trait<T> +'a` is covariant w/r/t `'a`: self.add_constraints_from_region(current, r, variance); |