diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs | 240 |
1 files changed, 195 insertions, 45 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index f3b04b55a35..6a40ffebdad 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -7,7 +7,7 @@ use super::{ use crate::errors; use crate::infer::InferCtxt; -use crate::traits::{NormalizeExt, ObligationCtxt}; +use crate::traits::{ImplDerivedObligationCause, NormalizeExt, ObligationCtxt}; use hir::def::CtorOf; use rustc_data_structures::fx::FxHashSet; @@ -2973,7 +2973,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { | ObligationCauseCode::ObjectTypeBound(..) => {} ObligationCauseCode::RustCall => { if let Some(pred) = predicate.to_opt_poly_trait_pred() - && Some(pred.def_id()) == self.tcx.lang_items().sized_trait() + && Some(pred.def_id()) == tcx.lang_items().sized_trait() { err.note("argument required to be sized due to `extern \"rust-call\"` ABI"); } @@ -3022,15 +3022,15 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { let def_id = trait_pred.def_id(); let visible_item = if let Some(local) = def_id.as_local() { // Check for local traits being reachable. - let vis = &self.tcx.resolutions(()).effective_visibilities; + let vis = &tcx.resolutions(()).effective_visibilities; // Account for non-`pub` traits in the root of the local crate. - let is_locally_reachable = self.tcx.parent(def_id).is_crate_root(); + let is_locally_reachable = tcx.parent(def_id).is_crate_root(); vis.is_reachable(local) || is_locally_reachable } else { // Check for foreign traits being reachable. - self.tcx.visible_parent_map(()).get(&def_id).is_some() + tcx.visible_parent_map(()).get(&def_id).is_some() }; - if Some(def_id) == self.tcx.lang_items().sized_trait() + if Some(def_id) == tcx.lang_items().sized_trait() && let Some(hir::Node::TraitItem(hir::TraitItem { ident, kind: hir::TraitItemKind::Type(bounds, None), @@ -3039,7 +3039,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { // Do not suggest relaxing if there is an explicit `Sized` obligation. && !bounds.iter() .filter_map(|bound| bound.trait_ref()) - .any(|tr| tr.trait_def_id() == self.tcx.lang_items().sized_trait()) + .any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait()) { let (span, separator) = if let [.., last] = bounds { (last.span().shrink_to_hi(), " +") @@ -3102,10 +3102,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { } ObligationCauseCode::Coercion { source, target } => { let mut file = None; - let source = - self.tcx.short_ty_string(self.resolve_vars_if_possible(source), &mut file); - let target = - self.tcx.short_ty_string(self.resolve_vars_if_possible(target), &mut file); + let source = tcx.short_ty_string(self.resolve_vars_if_possible(source), &mut file); + let target = tcx.short_ty_string(self.resolve_vars_if_possible(target), &mut file); err.note(with_forced_trimmed_paths!(format!( "required for the cast from `{source}` to `{target}`", ))); @@ -3158,7 +3156,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information"); } - if self.tcx.sess.is_nightly_build() + if tcx.sess.is_nightly_build() && matches!(is_constable, IsConstable::Fn | IsConstable::Ctor) { err.help( @@ -3168,8 +3166,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { } } ObligationCauseCode::VariableType(hir_id) => { - let parent_node = self.tcx.hir().parent_id(hir_id); - match self.tcx.opt_hir_node(parent_node) { + let parent_node = tcx.hir().parent_id(hir_id); + match tcx.opt_hir_node(parent_node) { Some(Node::Local(hir::Local { ty: Some(ty), .. })) => { err.span_suggestion_verbose( ty.span.shrink_to_lo(), @@ -3207,7 +3205,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { err.note("all local variables must have a statically known size"); } } - if !self.tcx.features().unsized_locals { + if !tcx.features().unsized_locals { err.help("unsized locals are gated as an unstable feature"); } } @@ -3289,7 +3287,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { err.note("all function arguments must have a statically known size"); } if tcx.sess.opts.unstable_features.is_nightly_build() - && !self.tcx.features().unsized_fn_params + && !tcx.features().unsized_fn_params { err.help("unsized fn params are gated as an unstable feature"); } @@ -3358,7 +3356,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { "all values captured by value by a closure must have a statically known size", ); let hir::ExprKind::Closure(closure) = - self.tcx.hir_node_by_def_id(closure_def_id).expect_expr().kind + tcx.hir_node_by_def_id(closure_def_id).expect_expr().kind else { bug!("expected closure in SizedClosureCapture obligation"); }; @@ -3369,7 +3367,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { } } ObligationCauseCode::SizedCoroutineInterior(coroutine_def_id) => { - let what = match self.tcx.coroutine_kind(coroutine_def_id) { + let what = match tcx.coroutine_kind(coroutine_def_id) { None | Some(hir::CoroutineKind::Coroutine(_)) | Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)) => { @@ -3420,10 +3418,10 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { 'print: { if !is_upvar_tys_infer_tuple { let mut file = None; - let ty_str = self.tcx.short_ty_string(ty, &mut file); + let ty_str = tcx.short_ty_string(ty, &mut file); let msg = format!("required because it appears within the type `{ty_str}`"); match ty.kind() { - ty::Adt(def, _) => match self.tcx.opt_item_ident(def.did()) { + ty::Adt(def, _) => match tcx.opt_item_ident(def.did()) { Some(ident) => err.span_note(ident.span, msg), None => err.note(msg), }, @@ -3446,7 +3444,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { { break 'print; } - err.span_note(self.tcx.def_span(def_id), msg) + err.span_note(tcx.def_span(def_id), msg) } ty::CoroutineWitness(def_id, args) => { use std::fmt::Write; @@ -3463,7 +3461,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { err.note(msg.trim_end_matches(", ").to_string()) } ty::Coroutine(def_id, _) => { - let sp = self.tcx.def_span(def_id); + let sp = tcx.def_span(def_id); // Special-case this to say "async block" instead of `[static coroutine]`. let kind = tcx.coroutine_kind(def_id).unwrap(); @@ -3475,7 +3473,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { ) } ty::Closure(def_id, _) => err.span_note( - self.tcx.def_span(def_id), + tcx.def_span(def_id), "required because it's used within this closure", ), ty::Str => err.note("`str` is considered to contain a `[u8]` slice for auto trait purposes"), @@ -3519,14 +3517,12 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { self.resolve_vars_if_possible(data.derived.parent_trait_pred); let parent_def_id = parent_trait_pred.def_id(); let mut file = None; - let self_ty = - self.tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file); - let msg = format!( - "required for `{self_ty}` to implement `{}`", - parent_trait_pred.print_modifiers_and_trait_path() - ); + let self_ty_str = + tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file); + let trait_name = parent_trait_pred.print_modifiers_and_trait_path().to_string(); + let msg = format!("required for `{self_ty_str}` to implement `{trait_name}`"); let mut is_auto_trait = false; - match self.tcx.hir().get_if_local(data.impl_or_alias_def_id) { + match tcx.hir().get_if_local(data.impl_or_alias_def_id) { Some(Node::Item(hir::Item { kind: hir::ItemKind::Trait(is_auto, ..), ident, @@ -3538,7 +3534,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { err.span_note(ident.span, msg); } Some(Node::Item(hir::Item { - kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }), + kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, generics, .. }), .. })) => { let mut spans = Vec::with_capacity(2); @@ -3565,6 +3561,15 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { ); } err.span_note(spans, msg); + point_at_assoc_type_restriction( + tcx, + err, + &self_ty_str, + &trait_name, + predicate, + &generics, + &data, + ); } _ => { err.note(msg); @@ -3618,9 +3623,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { pluralize!(count) )); let mut file = None; - let self_ty = self - .tcx - .short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file); + let self_ty = + tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file); err.note(format!( "required for `{self_ty}` to implement `{}`", parent_trait_pred.print_modifiers_and_trait_path() @@ -3678,10 +3682,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { multispan.push_span_label(span, "required by this bound"); err.span_note( multispan, - format!( - "required by a bound on the type alias `{}`", - self.infcx.tcx.item_name(def_id) - ), + format!("required by a bound on the type alias `{}`", tcx.item_name(def_id)), ); } ObligationCauseCode::FunctionArgumentObligation { @@ -3712,25 +3713,23 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { }); } ObligationCauseCode::CompareImplItemObligation { trait_item_def_id, kind, .. } => { - let item_name = self.tcx.item_name(trait_item_def_id); + let item_name = tcx.item_name(trait_item_def_id); let msg = format!( "the requirement `{predicate}` appears on the `impl`'s {kind} \ `{item_name}` but not on the corresponding trait's {kind}", ); - let sp = self - .tcx + let sp = tcx .opt_item_ident(trait_item_def_id) .map(|i| i.span) - .unwrap_or_else(|| self.tcx.def_span(trait_item_def_id)); + .unwrap_or_else(|| tcx.def_span(trait_item_def_id)); let mut assoc_span: MultiSpan = sp.into(); assoc_span.push_span_label( sp, format!("this trait's {kind} doesn't have the requirement `{predicate}`"), ); - if let Some(ident) = self - .tcx + if let Some(ident) = tcx .opt_associated_item(trait_item_def_id) - .and_then(|i| self.tcx.opt_item_ident(i.container_id(self.tcx))) + .and_then(|i| tcx.opt_item_ident(i.container_id(tcx))) { assoc_span.push_span_label(ident.span, "in this trait"); } @@ -4820,6 +4819,29 @@ fn hint_missing_borrow<'tcx>( } } +/// Collect all the paths that reference `Self`. +/// Used to suggest replacing associated types with an explicit type in `where` clauses. +#[derive(Debug)] +pub struct SelfVisitor<'v> { + pub paths: Vec<&'v hir::Ty<'v>>, + pub name: Option<Symbol>, +} + +impl<'v> Visitor<'v> for SelfVisitor<'v> { + fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { + if let hir::TyKind::Path(path) = ty.kind + && let hir::QPath::TypeRelative(inner_ty, segment) = path + && (Some(segment.ident.name) == self.name || self.name.is_none()) + && let hir::TyKind::Path(inner_path) = inner_ty.kind + && let hir::QPath::Resolved(None, inner_path) = inner_path + && let Res::SelfTyAlias { .. } = inner_path.res + { + self.paths.push(ty); + } + hir::intravisit::walk_ty(self, ty); + } +} + /// Collect all the returned expressions within the input expression. /// Used to point at the return spans when we want to suggest some change to them. #[derive(Default)] @@ -5064,6 +5086,134 @@ pub fn suggest_desugaring_async_fn_to_impl_future_in_trait<'tcx>( Some(sugg) } +/// On `impl` evaluation cycles, look for `Self::AssocTy` restrictions in `where` clauses, explain +/// they are not allowed and if possible suggest alternatives. +fn point_at_assoc_type_restriction( + tcx: TyCtxt<'_>, + err: &mut Diagnostic, + self_ty_str: &str, + trait_name: &str, + predicate: ty::Predicate<'_>, + generics: &hir::Generics<'_>, + data: &ImplDerivedObligationCause<'_>, +) { + let ty::PredicateKind::Clause(clause) = predicate.kind().skip_binder() else { + return; + }; + let ty::ClauseKind::Projection(proj) = clause else { + return; + }; + let name = tcx.item_name(proj.projection_ty.def_id); + let mut predicates = generics.predicates.iter().peekable(); + let mut prev: Option<&hir::WhereBoundPredicate<'_>> = None; + while let Some(pred) = predicates.next() { + let hir::WherePredicate::BoundPredicate(pred) = pred else { + continue; + }; + let mut bounds = pred.bounds.iter().peekable(); + while let Some(bound) = bounds.next() { + let Some(trait_ref) = bound.trait_ref() else { + continue; + }; + if bound.span() != data.span { + continue; + } + if let hir::TyKind::Path(path) = pred.bounded_ty.kind + && let hir::QPath::TypeRelative(ty, segment) = path + && segment.ident.name == name + && let hir::TyKind::Path(inner_path) = ty.kind + && let hir::QPath::Resolved(None, inner_path) = inner_path + && let Res::SelfTyAlias { .. } = inner_path.res + { + // The following block is to determine the right span to delete for this bound + // that will leave valid code after the suggestion is applied. + let span = if pred.origin == hir::PredicateOrigin::WhereClause + && generics + .predicates + .iter() + .filter(|p| { + matches!( + p, + hir::WherePredicate::BoundPredicate(p) + if hir::PredicateOrigin::WhereClause == p.origin + ) + }) + .count() + == 1 + { + // There's only one `where` bound, that needs to be removed. Remove the whole + // `where` clause. + generics.where_clause_span + } else if let Some(hir::WherePredicate::BoundPredicate(next)) = predicates.peek() + && pred.origin == next.origin + { + // There's another bound, include the comma for the current one. + pred.span.until(next.span) + } else if let Some(prev) = prev + && pred.origin == prev.origin + { + // Last bound, try to remove the previous comma. + prev.span.shrink_to_hi().to(pred.span) + } else if pred.origin == hir::PredicateOrigin::WhereClause { + pred.span.with_hi(generics.where_clause_span.hi()) + } else { + pred.span + }; + + err.span_suggestion_verbose( + span, + "associated type for the current `impl` cannot be restricted in `where` \ + clauses, remove this bound", + "", + Applicability::MaybeIncorrect, + ); + } + if let Some(new) = + tcx.associated_items(data.impl_or_alias_def_id).find_by_name_and_kind( + tcx, + Ident::with_dummy_span(name), + ty::AssocKind::Type, + data.impl_or_alias_def_id, + ) + { + // The associated type is specified in the `impl` we're + // looking at. Point at it. + let span = tcx.def_span(new.def_id); + err.span_label( + span, + format!( + "associated type `<{self_ty_str} as {trait_name}>::{name}` is specified \ + here", + ), + ); + // Search for the associated type `Self::{name}`, get + // its type and suggest replacing the bound with it. + let mut visitor = SelfVisitor { paths: vec![], name: Some(name) }; + visitor.visit_trait_ref(trait_ref); + for path in visitor.paths { + err.span_suggestion_verbose( + path.span, + "replace the associated type with the type specified in this `impl`", + tcx.type_of(new.def_id).skip_binder().to_string(), + Applicability::MachineApplicable, + ); + } + } else { + let mut visitor = SelfVisitor { paths: vec![], name: None }; + visitor.visit_trait_ref(trait_ref); + let span: MultiSpan = + visitor.paths.iter().map(|p| p.span).collect::<Vec<Span>>().into(); + err.span_note( + span, + "associated types for the current `impl` cannot be restricted in `where` \ + clauses", + ); + } + } + prev = Some(pred); + } +} + fn get_deref_type_and_refs(mut ty: Ty<'_>) -> (Ty<'_>, Vec<hir::Mutability>) { let mut refs = vec![]; |