| use crate::astconv::AstConv; |
| use crate::errors::{ |
| AssocTypeBindingNotAllowed, ManualImplementation, MissingTypeParams, |
| ParenthesizedFnTraitExpansion, |
| }; |
| use crate::traits::error_reporting::report_object_safety_error; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_errors::{pluralize, struct_span_err, Applicability, Diagnostic, ErrorGuaranteed}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LocalDefId}; |
| use rustc_infer::traits::FulfillmentError; |
| use rustc_middle::ty::{self, suggest_constraining_type_param, Ty, TyCtxt}; |
| use rustc_session::parse::feature_err; |
| use rustc_span::edit_distance::find_best_match_for_name; |
| use rustc_span::symbol::{sym, Ident}; |
| use rustc_span::{Span, Symbol, DUMMY_SP}; |
| use rustc_trait_selection::traits::object_safety_violations_for_assoc_item; |
| |
| use std::collections::BTreeSet; |
| |
| impl<'o, 'tcx> dyn AstConv<'tcx> + 'o { |
| /// On missing type parameters, emit an E0393 error and provide a structured suggestion using |
| /// the type parameter's name as a placeholder. |
| pub(crate) fn complain_about_missing_type_params( |
| &self, |
| missing_type_params: Vec<Symbol>, |
| def_id: DefId, |
| span: Span, |
| empty_generic_args: bool, |
| ) { |
| if missing_type_params.is_empty() { |
| return; |
| } |
| |
| self.tcx().sess.emit_err(MissingTypeParams { |
| span, |
| def_span: self.tcx().def_span(def_id), |
| span_snippet: self.tcx().sess.source_map().span_to_snippet(span).ok(), |
| missing_type_params, |
| empty_generic_args, |
| }); |
| } |
| |
| /// When the code is using the `Fn` traits directly, instead of the `Fn(A) -> B` syntax, emit |
| /// an error and attempt to build a reasonable structured suggestion. |
| pub(crate) fn complain_about_internal_fn_trait( |
| &self, |
| span: Span, |
| trait_def_id: DefId, |
| trait_segment: &'_ hir::PathSegment<'_>, |
| is_impl: bool, |
| ) { |
| if self.tcx().features().unboxed_closures { |
| return; |
| } |
| |
| let trait_def = self.tcx().trait_def(trait_def_id); |
| if !trait_def.paren_sugar { |
| if trait_segment.args().parenthesized == hir::GenericArgsParentheses::ParenSugar { |
| // For now, require that parenthetical notation be used only with `Fn()` etc. |
| let mut err = feature_err( |
| &self.tcx().sess.parse_sess, |
| sym::unboxed_closures, |
| span, |
| "parenthetical notation is only stable when used with `Fn`-family traits", |
| ); |
| err.emit(); |
| } |
| |
| return; |
| } |
| |
| let sess = self.tcx().sess; |
| |
| if trait_segment.args().parenthesized != hir::GenericArgsParentheses::ParenSugar { |
| // For now, require that parenthetical notation be used only with `Fn()` etc. |
| let mut err = feature_err( |
| &sess.parse_sess, |
| sym::unboxed_closures, |
| span, |
| "the precise format of `Fn`-family traits' type parameters is subject to change", |
| ); |
| // Do not suggest the other syntax if we are in trait impl: |
| // the desugaring would contain an associated type constraint. |
| if !is_impl { |
| err.span_suggestion( |
| span, |
| "use parenthetical notation instead", |
| fn_trait_to_string(self.tcx(), trait_segment, true), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| err.emit(); |
| } |
| |
| if is_impl { |
| let trait_name = self.tcx().def_path_str(trait_def_id); |
| self.tcx().sess.emit_err(ManualImplementation { span, trait_name }); |
| } |
| } |
| |
| pub(crate) fn complain_about_assoc_type_not_found<I>( |
| &self, |
| all_candidates: impl Fn() -> I, |
| ty_param_name: &str, |
| ty_param_def_id: Option<LocalDefId>, |
| assoc_name: Ident, |
| span: Span, |
| ) -> ErrorGuaranteed |
| where |
| I: Iterator<Item = ty::PolyTraitRef<'tcx>>, |
| { |
| // The fallback span is needed because `assoc_name` might be an `Fn()`'s `Output` without a |
| // valid span, so we point at the whole path segment instead. |
| let is_dummy = assoc_name.span == DUMMY_SP; |
| |
| let mut err = struct_span_err!( |
| self.tcx().sess, |
| if is_dummy { span } else { assoc_name.span }, |
| E0220, |
| "associated type `{}` not found for `{}`", |
| assoc_name, |
| ty_param_name |
| ); |
| |
| if is_dummy { |
| err.span_label(span, format!("associated type `{assoc_name}` not found")); |
| return err.emit(); |
| } |
| |
| let all_candidate_names: Vec<_> = all_candidates() |
| .flat_map(|r| self.tcx().associated_items(r.def_id()).in_definition_order()) |
| .filter_map(|item| { |
| if !item.is_impl_trait_in_trait() && item.kind == ty::AssocKind::Type { |
| Some(item.name) |
| } else { |
| None |
| } |
| }) |
| .collect(); |
| |
| if let Some(suggested_name) = |
| find_best_match_for_name(&all_candidate_names, assoc_name.name, None) |
| { |
| err.span_suggestion( |
| assoc_name.span, |
| "there is an associated type with a similar name", |
| suggested_name, |
| Applicability::MaybeIncorrect, |
| ); |
| return err.emit(); |
| } |
| |
| // If we didn't find a good item in the supertraits (or couldn't get |
| // the supertraits), like in ItemCtxt, then look more generally from |
| // all visible traits. If there's one clear winner, just suggest that. |
| |
| let visible_traits: Vec<_> = self |
| .tcx() |
| .all_traits() |
| .filter(|trait_def_id| { |
| let viz = self.tcx().visibility(*trait_def_id); |
| let def_id = self.item_def_id(); |
| viz.is_accessible_from(def_id, self.tcx()) |
| }) |
| .collect(); |
| |
| let wider_candidate_names: Vec<_> = visible_traits |
| .iter() |
| .flat_map(|trait_def_id| { |
| self.tcx().associated_items(*trait_def_id).in_definition_order() |
| }) |
| .filter_map(|item| { |
| if !item.is_impl_trait_in_trait() && item.kind == ty::AssocKind::Type { |
| Some(item.name) |
| } else { |
| None |
| } |
| }) |
| .collect(); |
| |
| if let Some(suggested_name) = |
| find_best_match_for_name(&wider_candidate_names, assoc_name.name, None) |
| { |
| if let [best_trait] = visible_traits |
| .iter() |
| .filter(|trait_def_id| { |
| self.tcx() |
| .associated_items(*trait_def_id) |
| .filter_by_name_unhygienic(suggested_name) |
| .any(|item| item.kind == ty::AssocKind::Type) |
| }) |
| .collect::<Vec<_>>()[..] |
| { |
| let trait_name = self.tcx().def_path_str(*best_trait); |
| let an = if suggested_name != assoc_name.name { "a similarly named" } else { "an" }; |
| err.span_label( |
| assoc_name.span, |
| format!( |
| "there is {an} associated type `{suggested_name}` in the \ |
| trait `{trait_name}`", |
| ), |
| ); |
| let hir = self.tcx().hir(); |
| if let Some(def_id) = ty_param_def_id |
| && let parent = hir.get_parent_item(hir.local_def_id_to_hir_id(def_id)) |
| && let Some(generics) = hir.get_generics(parent.def_id) |
| { |
| if generics.bounds_for_param(def_id) |
| .flat_map(|pred| pred.bounds.iter()) |
| .any(|b| match b { |
| hir::GenericBound::Trait(t, ..) => { |
| t.trait_ref.trait_def_id().as_ref() == Some(best_trait) |
| } |
| _ => false, |
| }) |
| { |
| // The type param already has a bound for `trait_name`, we just need to |
| // change the associated type. |
| err.span_suggestion_verbose( |
| assoc_name.span, |
| format!( |
| "change the associated type name to use `{suggested_name}` from \ |
| `{trait_name}`", |
| ), |
| suggested_name.to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } else if suggest_constraining_type_param( |
| self.tcx(), |
| generics, |
| &mut err, |
| &ty_param_name, |
| &trait_name, |
| None, |
| None, |
| ) |
| && suggested_name != assoc_name.name |
| { |
| // We suggested constraining a type parameter, but the associated type on it |
| // was also not an exact match, so we also suggest changing it. |
| err.span_suggestion_verbose( |
| assoc_name.span, |
| "and also change the associated type name", |
| suggested_name.to_string(), |
| Applicability::MaybeIncorrect, |
| ); |
| } |
| } |
| return err.emit(); |
| } |
| } |
| |
| // If we still couldn't find any associated type, and only one associated type exists, |
| // suggests using it. |
| |
| if all_candidate_names.len() == 1 { |
| // this should still compile, except on `#![feature(associated_type_defaults)]` |
| // where it could suggests `type A = Self::A`, thus recursing infinitely |
| let applicability = if self.tcx().features().associated_type_defaults { |
| Applicability::Unspecified |
| } else { |
| Applicability::MaybeIncorrect |
| }; |
| |
| err.span_suggestion( |
| assoc_name.span, |
| format!("`{ty_param_name}` has the following associated type"), |
| all_candidate_names.first().unwrap().to_string(), |
| applicability, |
| ); |
| } else { |
| err.span_label(assoc_name.span, format!("associated type `{assoc_name}` not found")); |
| } |
| |
| err.emit() |
| } |
| |
| pub(crate) fn complain_about_ambiguous_inherent_assoc_type( |
| &self, |
| name: Ident, |
| candidates: Vec<DefId>, |
| span: Span, |
| ) -> ErrorGuaranteed { |
| let mut err = struct_span_err!( |
| self.tcx().sess, |
| name.span, |
| E0034, |
| "multiple applicable items in scope" |
| ); |
| err.span_label(name.span, format!("multiple `{name}` found")); |
| self.note_ambiguous_inherent_assoc_type(&mut err, candidates, span); |
| err.emit() |
| } |
| |
| // FIXME(fmease): Heavily adapted from `rustc_hir_typeck::method::suggest`. Deduplicate. |
| fn note_ambiguous_inherent_assoc_type( |
| &self, |
| err: &mut Diagnostic, |
| candidates: Vec<DefId>, |
| span: Span, |
| ) { |
| let tcx = self.tcx(); |
| |
| // Dynamic limit to avoid hiding just one candidate, which is silly. |
| let limit = if candidates.len() == 5 { 5 } else { 4 }; |
| |
| for (index, &item) in candidates.iter().take(limit).enumerate() { |
| let impl_ = tcx.impl_of_method(item).unwrap(); |
| |
| let note_span = if item.is_local() { |
| Some(tcx.def_span(item)) |
| } else if impl_.is_local() { |
| Some(tcx.def_span(impl_)) |
| } else { |
| None |
| }; |
| |
| let title = if candidates.len() > 1 { |
| format!("candidate #{}", index + 1) |
| } else { |
| "the candidate".into() |
| }; |
| |
| let impl_ty = tcx.at(span).type_of(impl_).instantiate_identity(); |
| let note = format!("{title} is defined in an impl for the type `{impl_ty}`"); |
| |
| if let Some(span) = note_span { |
| err.span_note(span, note); |
| } else { |
| err.note(note); |
| } |
| } |
| if candidates.len() > limit { |
| err.note(format!("and {} others", candidates.len() - limit)); |
| } |
| } |
| |
| // FIXME(inherent_associated_types): Find similarly named associated types and suggest them. |
| pub(crate) fn complain_about_inherent_assoc_type_not_found( |
| &self, |
| name: Ident, |
| self_ty: Ty<'tcx>, |
| candidates: Vec<(DefId, (DefId, DefId))>, |
| fulfillment_errors: Vec<FulfillmentError<'tcx>>, |
| span: Span, |
| ) -> ErrorGuaranteed { |
| // FIXME(fmease): This was copied in parts from an old version of `rustc_hir_typeck::method::suggest`. |
| // Either |
| // * update this code by applying changes similar to #106702 or by taking a |
| // Vec<(DefId, (DefId, DefId), Option<Vec<FulfillmentError<'tcx>>>)> or |
| // * deduplicate this code across the two crates. |
| |
| let tcx = self.tcx(); |
| |
| let adt_did = self_ty.ty_adt_def().map(|def| def.did()); |
| let add_def_label = |err: &mut Diagnostic| { |
| if let Some(did) = adt_did { |
| err.span_label( |
| tcx.def_span(did), |
| format!("associated item `{name}` not found for this {}", tcx.def_descr(did)), |
| ); |
| } |
| }; |
| |
| if fulfillment_errors.is_empty() { |
| // FIXME(fmease): Copied from `rustc_hir_typeck::method::probe`. Deduplicate. |
| |
| let limit = if candidates.len() == 5 { 5 } else { 4 }; |
| let type_candidates = candidates |
| .iter() |
| .take(limit) |
| .map(|&(impl_, _)| { |
| format!("- `{}`", tcx.at(span).type_of(impl_).instantiate_identity()) |
| }) |
| .collect::<Vec<_>>() |
| .join("\n"); |
| let additional_types = if candidates.len() > limit { |
| format!("\nand {} more types", candidates.len() - limit) |
| } else { |
| String::new() |
| }; |
| |
| let mut err = struct_span_err!( |
| tcx.sess, |
| name.span, |
| E0220, |
| "associated type `{name}` not found for `{self_ty}` in the current scope" |
| ); |
| err.span_label(name.span, format!("associated item not found in `{self_ty}`")); |
| err.note(format!( |
| "the associated type was found for\n{type_candidates}{additional_types}", |
| )); |
| add_def_label(&mut err); |
| return err.emit(); |
| } |
| |
| let mut bound_spans = Vec::new(); |
| |
| let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| { |
| let msg = format!( |
| "doesn't satisfy `{}`", |
| if obligation.len() > 50 { quiet } else { obligation } |
| ); |
| match &self_ty.kind() { |
| // Point at the type that couldn't satisfy the bound. |
| ty::Adt(def, _) => bound_spans.push((tcx.def_span(def.did()), msg)), |
| // Point at the trait object that couldn't satisfy the bound. |
| ty::Dynamic(preds, _, _) => { |
| for pred in preds.iter() { |
| match pred.skip_binder() { |
| ty::ExistentialPredicate::Trait(tr) => { |
| bound_spans.push((tcx.def_span(tr.def_id), msg.clone())) |
| } |
| ty::ExistentialPredicate::Projection(_) |
| | ty::ExistentialPredicate::AutoTrait(_) => {} |
| } |
| } |
| } |
| // Point at the closure that couldn't satisfy the bound. |
| ty::Closure(def_id, _) => { |
| bound_spans.push((tcx.def_span(*def_id), format!("doesn't satisfy `{quiet}`"))) |
| } |
| _ => {} |
| } |
| }; |
| |
| let format_pred = |pred: ty::Predicate<'tcx>| { |
| let bound_predicate = pred.kind(); |
| match bound_predicate.skip_binder() { |
| ty::PredicateKind::Clause(ty::ClauseKind::Projection(pred)) => { |
| let pred = bound_predicate.rebind(pred); |
| // `<Foo as Iterator>::Item = String`. |
| let projection_ty = pred.skip_binder().projection_ty; |
| |
| let args_with_infer_self = tcx.mk_args_from_iter( |
| std::iter::once(Ty::new_var(tcx, ty::TyVid::from_u32(0)).into()) |
| .chain(projection_ty.args.iter().skip(1)), |
| ); |
| |
| let quiet_projection_ty = |
| ty::AliasTy::new(tcx, projection_ty.def_id, args_with_infer_self); |
| |
| let term = pred.skip_binder().term; |
| |
| let obligation = format!("{projection_ty} = {term}"); |
| let quiet = format!("{quiet_projection_ty} = {term}"); |
| |
| bound_span_label(projection_ty.self_ty(), &obligation, &quiet); |
| Some((obligation, projection_ty.self_ty())) |
| } |
| ty::PredicateKind::Clause(ty::ClauseKind::Trait(poly_trait_ref)) => { |
| let p = poly_trait_ref.trait_ref; |
| let self_ty = p.self_ty(); |
| let path = p.print_only_trait_path(); |
| let obligation = format!("{self_ty}: {path}"); |
| let quiet = format!("_: {path}"); |
| bound_span_label(self_ty, &obligation, &quiet); |
| Some((obligation, self_ty)) |
| } |
| _ => None, |
| } |
| }; |
| |
| // FIXME(fmease): `rustc_hir_typeck::method::suggest` uses a `skip_list` to filter out some bounds. |
| // I would do the same here if it didn't mean more code duplication. |
| let mut bounds: Vec<_> = fulfillment_errors |
| .into_iter() |
| .map(|error| error.root_obligation.predicate) |
| .filter_map(format_pred) |
| .map(|(p, _)| format!("`{p}`")) |
| .collect(); |
| bounds.sort(); |
| bounds.dedup(); |
| |
| let mut err = tcx.sess.struct_span_err( |
| name.span, |
| format!("the associated type `{name}` exists for `{self_ty}`, but its trait bounds were not satisfied") |
| ); |
| if !bounds.is_empty() { |
| err.note(format!( |
| "the following trait bounds were not satisfied:\n{}", |
| bounds.join("\n") |
| )); |
| } |
| err.span_label( |
| name.span, |
| format!("associated type cannot be referenced on `{self_ty}` due to unsatisfied trait bounds") |
| ); |
| |
| bound_spans.sort(); |
| bound_spans.dedup(); |
| for (span, msg) in bound_spans { |
| if !tcx.sess.source_map().is_span_accessible(span) { |
| continue; |
| } |
| err.span_label(span, msg); |
| } |
| add_def_label(&mut err); |
| err.emit() |
| } |
| |
| /// When there are any missing associated types, emit an E0191 error and attempt to supply a |
| /// reasonable suggestion on how to write it. For the case of multiple associated types in the |
| /// same trait bound have the same name (as they come from different supertraits), we instead |
| /// emit a generic note suggesting using a `where` clause to constraint instead. |
| pub(crate) fn complain_about_missing_associated_types( |
| &self, |
| associated_types: FxHashMap<Span, BTreeSet<DefId>>, |
| potential_assoc_types: Vec<Span>, |
| trait_bounds: &[hir::PolyTraitRef<'_>], |
| ) { |
| if associated_types.values().all(|v| v.is_empty()) { |
| return; |
| } |
| let tcx = self.tcx(); |
| // FIXME: Marked `mut` so that we can replace the spans further below with a more |
| // appropriate one, but this should be handled earlier in the span assignment. |
| let mut associated_types: FxHashMap<Span, Vec<_>> = associated_types |
| .into_iter() |
| .map(|(span, def_ids)| { |
| (span, def_ids.into_iter().map(|did| tcx.associated_item(did)).collect()) |
| }) |
| .collect(); |
| let mut names: FxHashMap<String, Vec<Symbol>> = Default::default(); |
| let mut names_len = 0; |
| |
| // Account for things like `dyn Foo + 'a`, like in tests `issue-22434.rs` and |
| // `issue-22560.rs`. |
| let mut trait_bound_spans: Vec<Span> = vec![]; |
| let mut object_safety_violations = false; |
| for (span, items) in &associated_types { |
| if !items.is_empty() { |
| trait_bound_spans.push(*span); |
| } |
| for assoc_item in items { |
| let trait_def_id = assoc_item.container_id(tcx); |
| names.entry(tcx.def_path_str(trait_def_id)).or_default().push(assoc_item.name); |
| names_len += 1; |
| |
| let violations = |
| object_safety_violations_for_assoc_item(tcx, trait_def_id, *assoc_item); |
| if !violations.is_empty() { |
| report_object_safety_error(tcx, *span, trait_def_id, &violations).emit(); |
| object_safety_violations = true; |
| } |
| } |
| } |
| if object_safety_violations { |
| return; |
| } |
| if let ([], [bound]) = (&potential_assoc_types[..], &trait_bounds) { |
| match bound.trait_ref.path.segments { |
| // FIXME: `trait_ref.path.span` can point to a full path with multiple |
| // segments, even though `trait_ref.path.segments` is of length `1`. Work |
| // around that bug here, even though it should be fixed elsewhere. |
| // This would otherwise cause an invalid suggestion. For an example, look at |
| // `tests/ui/issues/issue-28344.rs` where instead of the following: |
| // |
| // error[E0191]: the value of the associated type `Output` |
| // (from trait `std::ops::BitXor`) must be specified |
| // --> $DIR/issue-28344.rs:4:17 |
| // | |
| // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8); |
| // | ^^^^^^ help: specify the associated type: |
| // | `BitXor<Output = Type>` |
| // |
| // we would output: |
| // |
| // error[E0191]: the value of the associated type `Output` |
| // (from trait `std::ops::BitXor`) must be specified |
| // --> $DIR/issue-28344.rs:4:17 |
| // | |
| // LL | let x: u8 = BitXor::bitor(0 as u8, 0 as u8); |
| // | ^^^^^^^^^^^^^ help: specify the associated type: |
| // | `BitXor::bitor<Output = Type>` |
| [segment] if segment.args.is_none() => { |
| trait_bound_spans = vec![segment.ident.span]; |
| associated_types = associated_types |
| .into_values() |
| .map(|items| (segment.ident.span, items)) |
| .collect(); |
| } |
| _ => {} |
| } |
| } |
| |
| let mut names = names |
| .into_iter() |
| .map(|(trait_, mut assocs)| { |
| assocs.sort(); |
| format!( |
| "{} in `{trait_}`", |
| match &assocs[..] { |
| [] => String::new(), |
| [only] => format!("`{only}`"), |
| [assocs @ .., last] => format!( |
| "{} and `{last}`", |
| assocs.iter().map(|a| format!("`{a}`")).collect::<Vec<_>>().join(", ") |
| ), |
| } |
| ) |
| }) |
| .collect::<Vec<String>>(); |
| names.sort(); |
| let names = names.join(", "); |
| |
| trait_bound_spans.sort(); |
| let mut err = struct_span_err!( |
| tcx.sess, |
| trait_bound_spans, |
| E0191, |
| "the value of the associated type{} {} must be specified", |
| pluralize!(names_len), |
| names, |
| ); |
| let mut suggestions = vec![]; |
| let mut types_count = 0; |
| let mut where_constraints = vec![]; |
| let mut already_has_generics_args_suggestion = false; |
| for (span, assoc_items) in &associated_types { |
| let mut names: FxHashMap<_, usize> = FxHashMap::default(); |
| for item in assoc_items { |
| types_count += 1; |
| *names.entry(item.name).or_insert(0) += 1; |
| } |
| let mut dupes = false; |
| for item in assoc_items { |
| let prefix = if names[&item.name] > 1 { |
| let trait_def_id = item.container_id(tcx); |
| dupes = true; |
| format!("{}::", tcx.def_path_str(trait_def_id)) |
| } else { |
| String::new() |
| }; |
| if let Some(sp) = tcx.hir().span_if_local(item.def_id) { |
| err.span_label(sp, format!("`{}{}` defined here", prefix, item.name)); |
| } |
| } |
| if potential_assoc_types.len() == assoc_items.len() { |
| // When the amount of missing associated types equals the number of |
| // extra type arguments present. A suggesting to replace the generic args with |
| // associated types is already emitted. |
| already_has_generics_args_suggestion = true; |
| } else if let (Ok(snippet), false) = |
| (tcx.sess.source_map().span_to_snippet(*span), dupes) |
| { |
| let types: Vec<_> = |
| assoc_items.iter().map(|item| format!("{} = Type", item.name)).collect(); |
| let code = if snippet.ends_with('>') { |
| // The user wrote `Trait<'a>` or similar and we don't have a type we can |
| // suggest, but at least we can clue them to the correct syntax |
| // `Trait<'a, Item = Type>` while accounting for the `<'a>` in the |
| // suggestion. |
| format!("{}, {}>", &snippet[..snippet.len() - 1], types.join(", ")) |
| } else { |
| // The user wrote `Iterator`, so we don't have a type we can suggest, but at |
| // least we can clue them to the correct syntax `Iterator<Item = Type>`. |
| format!("{}<{}>", snippet, types.join(", ")) |
| }; |
| suggestions.push((*span, code)); |
| } else if dupes { |
| where_constraints.push(*span); |
| } |
| } |
| let where_msg = "consider introducing a new type parameter, adding `where` constraints \ |
| using the fully-qualified path to the associated types"; |
| if !where_constraints.is_empty() && suggestions.is_empty() { |
| // If there are duplicates associated type names and a single trait bound do not |
| // use structured suggestion, it means that there are multiple supertraits with |
| // the same associated type name. |
| err.help(where_msg); |
| } |
| if suggestions.len() != 1 || already_has_generics_args_suggestion { |
| // We don't need this label if there's an inline suggestion, show otherwise. |
| for (span, assoc_items) in &associated_types { |
| let mut names: FxHashMap<_, usize> = FxHashMap::default(); |
| for item in assoc_items { |
| types_count += 1; |
| *names.entry(item.name).or_insert(0) += 1; |
| } |
| let mut label = vec![]; |
| for item in assoc_items { |
| let postfix = if names[&item.name] > 1 { |
| let trait_def_id = item.container_id(tcx); |
| format!(" (from trait `{}`)", tcx.def_path_str(trait_def_id)) |
| } else { |
| String::new() |
| }; |
| label.push(format!("`{}`{}", item.name, postfix)); |
| } |
| if !label.is_empty() { |
| err.span_label( |
| *span, |
| format!( |
| "associated type{} {} must be specified", |
| pluralize!(label.len()), |
| label.join(", "), |
| ), |
| ); |
| } |
| } |
| } |
| suggestions.sort_by_key(|&(span, _)| span); |
| // There are cases where one bound points to a span within another bound's span, like when |
| // you have code like the following (#115019), so we skip providing a suggestion in those |
| // cases to avoid having a malformed suggestion. |
| // |
| // pub struct Flatten<I> { |
| // inner: <IntoIterator<Item: IntoIterator<Item: >>::IntoIterator as Item>::core, |
| // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| // | ^^^^^^^^^^^^^^^^^^^^^ |
| // | | |
| // | associated types `Item`, `IntoIter` must be specified |
| // associated types `Item`, `IntoIter` must be specified |
| // } |
| let overlaps = suggestions.windows(2).any(|pair| pair[0].0.overlaps(pair[1].0)); |
| if !suggestions.is_empty() && !overlaps { |
| err.multipart_suggestion( |
| format!("specify the associated type{}", pluralize!(types_count)), |
| suggestions, |
| Applicability::HasPlaceholders, |
| ); |
| if !where_constraints.is_empty() { |
| err.span_help(where_constraints, where_msg); |
| } |
| } |
| err.emit(); |
| } |
| } |
| |
| /// Emits an error regarding forbidden type binding associations |
| pub fn prohibit_assoc_ty_binding( |
| tcx: TyCtxt<'_>, |
| span: Span, |
| segment: Option<(&hir::PathSegment<'_>, Span)>, |
| ) { |
| tcx.sess.emit_err(AssocTypeBindingNotAllowed { |
| span, |
| fn_trait_expansion: if let Some((segment, span)) = segment |
| && segment.args().parenthesized == hir::GenericArgsParentheses::ParenSugar |
| { |
| Some(ParenthesizedFnTraitExpansion { |
| span, |
| expanded_type: fn_trait_to_string(tcx, segment, false), |
| }) |
| } else { |
| None |
| }, |
| }); |
| } |
| |
| pub(crate) fn fn_trait_to_string( |
| tcx: TyCtxt<'_>, |
| trait_segment: &hir::PathSegment<'_>, |
| parenthesized: bool, |
| ) -> String { |
| let args = trait_segment |
| .args |
| .as_ref() |
| .and_then(|args| args.args.get(0)) |
| .and_then(|arg| match arg { |
| hir::GenericArg::Type(ty) => match ty.kind { |
| hir::TyKind::Tup(t) => t |
| .iter() |
| .map(|e| tcx.sess.source_map().span_to_snippet(e.span)) |
| .collect::<Result<Vec<_>, _>>() |
| .map(|a| a.join(", ")), |
| _ => tcx.sess.source_map().span_to_snippet(ty.span), |
| } |
| .map(|s| { |
| // `s.empty()` checks to see if the type is the unit tuple, if so we don't want a comma |
| if parenthesized || s.is_empty() { format!("({s})") } else { format!("({s},)") } |
| }) |
| .ok(), |
| _ => None, |
| }) |
| .unwrap_or_else(|| "()".to_string()); |
| |
| let ret = trait_segment |
| .args() |
| .bindings |
| .iter() |
| .find_map(|b| match (b.ident.name == sym::Output, &b.kind) { |
| (true, hir::TypeBindingKind::Equality { term }) => { |
| let span = match term { |
| hir::Term::Ty(ty) => ty.span, |
| hir::Term::Const(c) => tcx.hir().span(c.hir_id), |
| }; |
| |
| (span != tcx.hir().span(trait_segment.hir_id)) |
| .then_some(tcx.sess.source_map().span_to_snippet(span).ok()) |
| .flatten() |
| } |
| _ => None, |
| }) |
| .unwrap_or_else(|| "()".to_string()); |
| |
| if parenthesized { |
| format!("{}{} -> {}", trait_segment.ident, args, ret) |
| } else { |
| format!("{}<{}, Output={}>", trait_segment.ident, args, ret) |
| } |
| } |
