diff options
Diffstat (limited to 'compiler/rustc_typeck/src/check/method/suggest.rs')
| -rw-r--r-- | compiler/rustc_typeck/src/check/method/suggest.rs | 2286 |
1 files changed, 2286 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/method/suggest.rs b/compiler/rustc_typeck/src/check/method/suggest.rs new file mode 100644 index 000000000..c92b93cbc --- /dev/null +++ b/compiler/rustc_typeck/src/check/method/suggest.rs @@ -0,0 +1,2286 @@ +//! Give useful errors and suggestions to users when an item can't be +//! found or is otherwise invalid. + +use crate::check::FnCtxt; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_errors::{ + pluralize, struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, + MultiSpan, +}; +use rustc_hir as hir; +use rustc_hir::def::DefKind; +use rustc_hir::def_id::DefId; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{ExprKind, Node, QPath}; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_middle::traits::util::supertraits; +use rustc_middle::ty::fast_reject::{simplify_type, TreatParams}; +use rustc_middle::ty::print::with_crate_prefix; +use rustc_middle::ty::ToPolyTraitRef; +use rustc_middle::ty::{self, DefIdTree, ToPredicate, Ty, TyCtxt, TypeVisitable}; +use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::Symbol; +use rustc_span::{lev_distance, source_map, ExpnKind, FileName, MacroKind, Span}; +use rustc_trait_selection::traits::error_reporting::on_unimplemented::InferCtxtExt as _; +use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; +use rustc_trait_selection::traits::{ + FulfillmentError, Obligation, ObligationCause, ObligationCauseCode, OnUnimplementedNote, +}; + +use std::cmp::Ordering; +use std::iter; + +use super::probe::{Mode, ProbeScope}; +use super::{super::suggest_call_constructor, CandidateSource, MethodError, NoMatchData}; + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + fn is_fn_ty(&self, ty: Ty<'tcx>, span: Span) -> bool { + let tcx = self.tcx; + match ty.kind() { + // Not all of these (e.g., unsafe fns) implement `FnOnce`, + // so we look for these beforehand. + ty::Closure(..) | ty::FnDef(..) | ty::FnPtr(_) => true, + // If it's not a simple function, look for things which implement `FnOnce`. + _ => { + let Some(fn_once) = tcx.lang_items().fn_once_trait() else { + return false; + }; + + // This conditional prevents us from asking to call errors and unresolved types. + // It might seem that we can use `predicate_must_hold_modulo_regions`, + // but since a Dummy binder is used to fill in the FnOnce trait's arguments, + // type resolution always gives a "maybe" here. + if self.autoderef(span, ty).any(|(ty, _)| { + info!("check deref {:?} error", ty); + matches!(ty.kind(), ty::Error(_) | ty::Infer(_)) + }) { + return false; + } + + self.autoderef(span, ty).any(|(ty, _)| { + info!("check deref {:?} impl FnOnce", ty); + self.probe(|_| { + let fn_once_substs = tcx.mk_substs_trait( + ty, + &[self + .next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::MiscVariable, + span, + }) + .into()], + ); + let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs); + let poly_trait_ref = ty::Binder::dummy(trait_ref); + let obligation = Obligation::misc( + span, + self.body_id, + self.param_env, + poly_trait_ref.without_const().to_predicate(tcx), + ); + self.predicate_may_hold(&obligation) + }) + }) + } + } + } + + fn is_slice_ty(&self, ty: Ty<'tcx>, span: Span) -> bool { + self.autoderef(span, ty).any(|(ty, _)| matches!(ty.kind(), ty::Slice(..) | ty::Array(..))) + } + + pub fn report_method_error( + &self, + mut span: Span, + rcvr_ty: Ty<'tcx>, + item_name: Ident, + source: SelfSource<'tcx>, + error: MethodError<'tcx>, + args: Option<&'tcx [hir::Expr<'tcx>]>, + ) -> Option<DiagnosticBuilder<'_, ErrorGuaranteed>> { + // Avoid suggestions when we don't know what's going on. + if rcvr_ty.references_error() { + return None; + } + + let report_candidates = |span: Span, + err: &mut Diagnostic, + mut sources: Vec<CandidateSource>, + sugg_span: Span| { + sources.sort(); + sources.dedup(); + // Dynamic limit to avoid hiding just one candidate, which is silly. + let limit = if sources.len() == 5 { 5 } else { 4 }; + + for (idx, source) in sources.iter().take(limit).enumerate() { + match *source { + CandidateSource::Impl(impl_did) => { + // Provide the best span we can. Use the item, if local to crate, else + // the impl, if local to crate (item may be defaulted), else nothing. + let Some(item) = self.associated_value(impl_did, item_name).or_else(|| { + let impl_trait_ref = self.tcx.impl_trait_ref(impl_did)?; + self.associated_value(impl_trait_ref.def_id, item_name) + }) else { + continue; + }; + + let note_span = if item.def_id.is_local() { + Some(self.tcx.def_span(item.def_id)) + } else if impl_did.is_local() { + Some(self.tcx.def_span(impl_did)) + } else { + None + }; + + let impl_ty = self.tcx.at(span).type_of(impl_did); + + let insertion = match self.tcx.impl_trait_ref(impl_did) { + None => String::new(), + Some(trait_ref) => format!( + " of the trait `{}`", + self.tcx.def_path_str(trait_ref.def_id) + ), + }; + + let (note_str, idx) = if sources.len() > 1 { + ( + format!( + "candidate #{} is defined in an impl{} for the type `{}`", + idx + 1, + insertion, + impl_ty, + ), + Some(idx + 1), + ) + } else { + ( + format!( + "the candidate is defined in an impl{} for the type `{}`", + insertion, impl_ty, + ), + None, + ) + }; + if let Some(note_span) = note_span { + // We have a span pointing to the method. Show note with snippet. + err.span_note(note_span, ¬e_str); + } else { + err.note(¬e_str); + } + if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_did) { + let path = self.tcx.def_path_str(trait_ref.def_id); + + let ty = match item.kind { + ty::AssocKind::Const | ty::AssocKind::Type => rcvr_ty, + ty::AssocKind::Fn => self + .tcx + .fn_sig(item.def_id) + .inputs() + .skip_binder() + .get(0) + .filter(|ty| ty.is_region_ptr() && !rcvr_ty.is_region_ptr()) + .copied() + .unwrap_or(rcvr_ty), + }; + print_disambiguation_help( + item_name, + args, + err, + path, + ty, + item.kind, + item.def_id, + sugg_span, + idx, + self.tcx.sess.source_map(), + item.fn_has_self_parameter, + ); + } + } + CandidateSource::Trait(trait_did) => { + let Some(item) = self.associated_value(trait_did, item_name) else { continue }; + let item_span = self.tcx.def_span(item.def_id); + let idx = if sources.len() > 1 { + let msg = &format!( + "candidate #{} is defined in the trait `{}`", + idx + 1, + self.tcx.def_path_str(trait_did) + ); + err.span_note(item_span, msg); + Some(idx + 1) + } else { + let msg = &format!( + "the candidate is defined in the trait `{}`", + self.tcx.def_path_str(trait_did) + ); + err.span_note(item_span, msg); + None + }; + let path = self.tcx.def_path_str(trait_did); + print_disambiguation_help( + item_name, + args, + err, + path, + rcvr_ty, + item.kind, + item.def_id, + sugg_span, + idx, + self.tcx.sess.source_map(), + item.fn_has_self_parameter, + ); + } + } + } + if sources.len() > limit { + err.note(&format!("and {} others", sources.len() - limit)); + } + }; + + let sugg_span = if let SelfSource::MethodCall(expr) = source { + // Given `foo.bar(baz)`, `expr` is `bar`, but we want to point to the whole thing. + self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)).span + } else { + span + }; + + match error { + MethodError::NoMatch(NoMatchData { + static_candidates: static_sources, + unsatisfied_predicates, + out_of_scope_traits, + lev_candidate, + mode, + }) => { + let tcx = self.tcx; + + let actual = self.resolve_vars_if_possible(rcvr_ty); + let ty_str = self.ty_to_string(actual); + let is_method = mode == Mode::MethodCall; + let item_kind = if is_method { + "method" + } else if actual.is_enum() { + "variant or associated item" + } else { + match (item_name.as_str().chars().next(), actual.is_fresh_ty()) { + (Some(name), false) if name.is_lowercase() => "function or associated item", + (Some(_), false) => "associated item", + (Some(_), true) | (None, false) => "variant or associated item", + (None, true) => "variant", + } + }; + + if self.suggest_constraining_numerical_ty( + tcx, actual, source, span, item_kind, item_name, &ty_str, + ) { + return None; + } + + span = item_name.span; + + // Don't show generic arguments when the method can't be found in any implementation (#81576). + let mut ty_str_reported = ty_str.clone(); + if let ty::Adt(_, generics) = actual.kind() { + if generics.len() > 0 { + let mut autoderef = self.autoderef(span, actual); + let candidate_found = autoderef.any(|(ty, _)| { + if let ty::Adt(adt_deref, _) = ty.kind() { + self.tcx + .inherent_impls(adt_deref.did()) + .iter() + .filter_map(|def_id| self.associated_value(*def_id, item_name)) + .count() + >= 1 + } else { + false + } + }); + let has_deref = autoderef.step_count() > 0; + if !candidate_found && !has_deref && unsatisfied_predicates.is_empty() { + if let Some((path_string, _)) = ty_str.split_once('<') { + ty_str_reported = path_string.to_string(); + } + } + } + } + + let mut err = struct_span_err!( + tcx.sess, + span, + E0599, + "no {} named `{}` found for {} `{}` in the current scope", + item_kind, + item_name, + actual.prefix_string(self.tcx), + ty_str_reported, + ); + if actual.references_error() { + err.downgrade_to_delayed_bug(); + } + + if let Mode::MethodCall = mode && let SelfSource::MethodCall(cal) = source { + self.suggest_await_before_method( + &mut err, item_name, actual, cal, span, + ); + } + if let Some(span) = tcx.resolutions(()).confused_type_with_std_module.get(&span) { + err.span_suggestion( + span.shrink_to_lo(), + "you are looking for the module in `std`, not the primitive type", + "std::", + Applicability::MachineApplicable, + ); + } + if let ty::RawPtr(_) = &actual.kind() { + err.note( + "try using `<*const T>::as_ref()` to get a reference to the \ + type behind the pointer: https://doc.rust-lang.org/std/\ + primitive.pointer.html#method.as_ref", + ); + err.note( + "using `<*const T>::as_ref()` on a pointer which is unaligned or points \ + to invalid or uninitialized memory is undefined behavior", + ); + } + + let ty_span = match actual.kind() { + ty::Param(param_type) => { + let generics = self.tcx.generics_of(self.body_id.owner.to_def_id()); + let type_param = generics.type_param(param_type, self.tcx); + Some(self.tcx.def_span(type_param.def_id)) + } + ty::Adt(def, _) if def.did().is_local() => Some(tcx.def_span(def.did())), + _ => None, + }; + + if let Some(span) = ty_span { + err.span_label( + span, + format!( + "{item_kind} `{item_name}` not found for this {}", + actual.prefix_string(self.tcx) + ), + ); + } + + if self.is_fn_ty(rcvr_ty, span) { + if let SelfSource::MethodCall(expr) = source { + let suggest = if let ty::FnDef(def_id, _) = rcvr_ty.kind() { + if let Some(local_id) = def_id.as_local() { + let hir_id = tcx.hir().local_def_id_to_hir_id(local_id); + let node = tcx.hir().get(hir_id); + let fields = node.tuple_fields(); + if let Some(fields) = fields + && let Some(DefKind::Ctor(of, _)) = self.tcx.opt_def_kind(local_id) { + Some((fields.len(), of)) + } else { + None + } + } else { + // The logic here isn't smart but `associated_item_def_ids` + // doesn't work nicely on local. + if let DefKind::Ctor(of, _) = tcx.def_kind(def_id) { + let parent_def_id = tcx.parent(*def_id); + Some((tcx.associated_item_def_ids(parent_def_id).len(), of)) + } else { + None + } + } + } else { + None + }; + + // If the function is a tuple constructor, we recommend that they call it + if let Some((fields, kind)) = suggest { + suggest_call_constructor(expr.span, kind, fields, &mut err); + } else { + // General case + err.span_label( + expr.span, + "this is a function, perhaps you wish to call it", + ); + } + } + } + + let mut custom_span_label = false; + + if !static_sources.is_empty() { + err.note( + "found the following associated functions; to be used as methods, \ + functions must have a `self` parameter", + ); + err.span_label(span, "this is an associated function, not a method"); + custom_span_label = true; + } + if static_sources.len() == 1 { + let ty_str = + if let Some(CandidateSource::Impl(impl_did)) = static_sources.get(0) { + // When the "method" is resolved through dereferencing, we really want the + // original type that has the associated function for accurate suggestions. + // (#61411) + let ty = tcx.at(span).type_of(*impl_did); + match (&ty.peel_refs().kind(), &actual.peel_refs().kind()) { + (ty::Adt(def, _), ty::Adt(def_actual, _)) if def == def_actual => { + // Use `actual` as it will have more `substs` filled in. + self.ty_to_value_string(actual.peel_refs()) + } + _ => self.ty_to_value_string(ty.peel_refs()), + } + } else { + self.ty_to_value_string(actual.peel_refs()) + }; + if let SelfSource::MethodCall(expr) = source { + err.span_suggestion( + expr.span.to(span), + "use associated function syntax instead", + format!("{}::{}", ty_str, item_name), + Applicability::MachineApplicable, + ); + } else { + err.help(&format!("try with `{}::{}`", ty_str, item_name,)); + } + + report_candidates(span, &mut err, static_sources, sugg_span); + } else if static_sources.len() > 1 { + report_candidates(span, &mut err, static_sources, sugg_span); + } + + let mut bound_spans = vec![]; + let mut restrict_type_params = false; + let mut unsatisfied_bounds = false; + if item_name.name == sym::count && self.is_slice_ty(actual, span) { + let msg = "consider using `len` instead"; + if let SelfSource::MethodCall(_expr) = source { + err.span_suggestion_short( + span, + msg, + "len", + Applicability::MachineApplicable, + ); + } else { + err.span_label(span, msg); + } + if let Some(iterator_trait) = self.tcx.get_diagnostic_item(sym::Iterator) { + let iterator_trait = self.tcx.def_path_str(iterator_trait); + err.note(&format!("`count` is defined on `{iterator_trait}`, which `{actual}` does not implement")); + } + } else if !unsatisfied_predicates.is_empty() { + let mut type_params = FxHashMap::default(); + + // Pick out the list of unimplemented traits on the receiver. + // This is used for custom error messages with the `#[rustc_on_unimplemented]` attribute. + let mut unimplemented_traits = FxHashMap::default(); + let mut unimplemented_traits_only = true; + for (predicate, _parent_pred, cause) in &unsatisfied_predicates { + if let (ty::PredicateKind::Trait(p), Some(cause)) = + (predicate.kind().skip_binder(), cause.as_ref()) + { + if p.trait_ref.self_ty() != rcvr_ty { + // This is necessary, not just to keep the errors clean, but also + // because our derived obligations can wind up with a trait ref that + // requires a different param_env to be correctly compared. + continue; + } + unimplemented_traits.entry(p.trait_ref.def_id).or_insert(( + predicate.kind().rebind(p.trait_ref), + Obligation { + cause: cause.clone(), + param_env: self.param_env, + predicate: *predicate, + recursion_depth: 0, + }, + )); + } + } + + // Make sure that, if any traits other than the found ones were involved, + // we don't don't report an unimplemented trait. + // We don't want to say that `iter::Cloned` is not an iterator, just + // because of some non-Clone item being iterated over. + for (predicate, _parent_pred, _cause) in &unsatisfied_predicates { + match predicate.kind().skip_binder() { + ty::PredicateKind::Trait(p) + if unimplemented_traits.contains_key(&p.trait_ref.def_id) => {} + _ => { + unimplemented_traits_only = false; + break; + } + } + } + + let mut collect_type_param_suggestions = + |self_ty: Ty<'tcx>, parent_pred: ty::Predicate<'tcx>, obligation: &str| { + // We don't care about regions here, so it's fine to skip the binder here. + if let (ty::Param(_), ty::PredicateKind::Trait(p)) = + (self_ty.kind(), parent_pred.kind().skip_binder()) + { + let node = match p.trait_ref.self_ty().kind() { + ty::Param(_) => { + // Account for `fn` items like in `issue-35677.rs` to + // suggest restricting its type params. + let did = self.tcx.hir().body_owner_def_id(hir::BodyId { + hir_id: self.body_id, + }); + Some( + self.tcx + .hir() + .get(self.tcx.hir().local_def_id_to_hir_id(did)), + ) + } + ty::Adt(def, _) => def.did().as_local().map(|def_id| { + self.tcx + .hir() + .get(self.tcx.hir().local_def_id_to_hir_id(def_id)) + }), + _ => None, + }; + if let Some(hir::Node::Item(hir::Item { kind, .. })) = node { + if let Some(g) = kind.generics() { + let key = ( + g.tail_span_for_predicate_suggestion(), + g.add_where_or_trailing_comma(), + ); + type_params + .entry(key) + .or_insert_with(FxHashSet::default) + .insert(obligation.to_owned()); + } + } + } + }; + 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((self.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((self.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 mut format_pred = |pred: ty::Predicate<'tcx>| { + let bound_predicate = pred.kind(); + match bound_predicate.skip_binder() { + ty::PredicateKind::Projection(pred) => { + let pred = bound_predicate.rebind(pred); + // `<Foo as Iterator>::Item = String`. + let projection_ty = pred.skip_binder().projection_ty; + + let substs_with_infer_self = tcx.mk_substs( + iter::once(tcx.mk_ty_var(ty::TyVid::from_u32(0)).into()) + .chain(projection_ty.substs.iter().skip(1)), + ); + + let quiet_projection_ty = ty::ProjectionTy { + substs: substs_with_infer_self, + item_def_id: projection_ty.item_def_id, + }; + + 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::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, + } + }; + + // Find all the requirements that come from a local `impl` block. + let mut skip_list: FxHashSet<_> = Default::default(); + let mut spanned_predicates: FxHashMap<MultiSpan, _> = Default::default(); + for (data, p, parent_p, impl_def_id, cause) in unsatisfied_predicates + .iter() + .filter_map(|(p, parent, c)| c.as_ref().map(|c| (p, parent, c))) + .filter_map(|(p, parent, c)| match c.code() { + ObligationCauseCode::ImplDerivedObligation(ref data) => { + Some((&data.derived, p, parent, data.impl_def_id, data)) + } + _ => None, + }) + { + let parent_trait_ref = data.parent_trait_pred; + let path = parent_trait_ref.print_modifiers_and_trait_path(); + let tr_self_ty = parent_trait_ref.skip_binder().self_ty(); + let unsatisfied_msg = "unsatisfied trait bound introduced here"; + let derive_msg = + "unsatisfied trait bound introduced in this `derive` macro"; + match self.tcx.hir().get_if_local(impl_def_id) { + // Unmet obligation comes from a `derive` macro, point at it once to + // avoid multiple span labels pointing at the same place. + Some(Node::Item(hir::Item { + kind: hir::ItemKind::Trait(..), + ident, + .. + })) if matches!( + ident.span.ctxt().outer_expn_data().kind, + ExpnKind::Macro(MacroKind::Derive, _) + ) => + { + let span = ident.span.ctxt().outer_expn_data().call_site; + let mut spans: MultiSpan = span.into(); + spans.push_span_label(span, derive_msg); + let entry = spanned_predicates.entry(spans); + entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p); + } + + Some(Node::Item(hir::Item { + kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }), + .. + })) if matches!( + self_ty.span.ctxt().outer_expn_data().kind, + ExpnKind::Macro(MacroKind::Derive, _) + ) || matches!( + of_trait.as_ref().map(|t| t + .path + .span + .ctxt() + .outer_expn_data() + .kind), + Some(ExpnKind::Macro(MacroKind::Derive, _)) + ) => + { + let span = self_ty.span.ctxt().outer_expn_data().call_site; + let mut spans: MultiSpan = span.into(); + spans.push_span_label(span, derive_msg); + let entry = spanned_predicates.entry(spans); + entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p); + } + + // Unmet obligation coming from a `trait`. + Some(Node::Item(hir::Item { + kind: hir::ItemKind::Trait(..), + ident, + span: item_span, + .. + })) if !matches!( + ident.span.ctxt().outer_expn_data().kind, + ExpnKind::Macro(MacroKind::Derive, _) + ) => + { + if let Some(pred) = parent_p { + // Done to add the "doesn't satisfy" `span_label`. + let _ = format_pred(*pred); + } + skip_list.insert(p); + let mut spans = if cause.span != *item_span { + let mut spans: MultiSpan = cause.span.into(); + spans.push_span_label(cause.span, unsatisfied_msg); + spans + } else { + ident.span.into() + }; + spans.push_span_label(ident.span, "in this trait"); + let entry = spanned_predicates.entry(spans); + entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p); + } + + // Unmet obligation coming from an `impl`. + Some(Node::Item(hir::Item { + kind: + hir::ItemKind::Impl(hir::Impl { + of_trait, self_ty, generics, .. + }), + span: item_span, + .. + })) if !matches!( + self_ty.span.ctxt().outer_expn_data().kind, + ExpnKind::Macro(MacroKind::Derive, _) + ) && !matches!( + of_trait.as_ref().map(|t| t + .path + .span + .ctxt() + .outer_expn_data() + .kind), + Some(ExpnKind::Macro(MacroKind::Derive, _)) + ) => + { + let sized_pred = + unsatisfied_predicates.iter().any(|(pred, _, _)| { + match pred.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => { + Some(pred.def_id()) + == self.tcx.lang_items().sized_trait() + && pred.polarity == ty::ImplPolarity::Positive + } + _ => false, + } + }); + for param in generics.params { + if param.span == cause.span && sized_pred { + let (sp, sugg) = match param.colon_span { + Some(sp) => (sp.shrink_to_hi(), " ?Sized +"), + None => (param.span.shrink_to_hi(), ": ?Sized"), + }; + err.span_suggestion_verbose( + sp, + "consider relaxing the type parameter's implicit \ + `Sized` bound", + sugg, + Applicability::MachineApplicable, + ); + } + } + if let Some(pred) = parent_p { + // Done to add the "doesn't satisfy" `span_label`. + let _ = format_pred(*pred); + } + skip_list.insert(p); + let mut spans = if cause.span != *item_span { + let mut spans: MultiSpan = cause.span.into(); + spans.push_span_label(cause.span, unsatisfied_msg); + spans + } else { + let mut spans = Vec::with_capacity(2); + if let Some(trait_ref) = of_trait { + spans.push(trait_ref.path.span); + } + spans.push(self_ty.span); + spans.into() + }; + if let Some(trait_ref) = of_trait { + spans.push_span_label(trait_ref.path.span, ""); + } + spans.push_span_label(self_ty.span, ""); + + let entry = spanned_predicates.entry(spans); + entry.or_insert_with(|| (path, tr_self_ty, Vec::new())).2.push(p); + } + _ => {} + } + } + let mut spanned_predicates: Vec<_> = spanned_predicates.into_iter().collect(); + spanned_predicates.sort_by_key(|(span, (_, _, _))| span.primary_span()); + for (span, (_path, _self_ty, preds)) in spanned_predicates { + let mut preds: Vec<_> = preds + .into_iter() + .filter_map(|pred| format_pred(*pred)) + .map(|(p, _)| format!("`{}`", p)) + .collect(); + preds.sort(); + preds.dedup(); + let msg = if let [pred] = &preds[..] { + format!("trait bound {} was not satisfied", pred) + } else { + format!( + "the following trait bounds were not satisfied:\n{}", + preds.join("\n"), + ) + }; + err.span_note(span, &msg); + unsatisfied_bounds = true; + } + + // The requirements that didn't have an `impl` span to show. + let mut bound_list = unsatisfied_predicates + .iter() + .filter_map(|(pred, parent_pred, _cause)| { + format_pred(*pred).map(|(p, self_ty)| { + collect_type_param_suggestions(self_ty, *pred, &p); + ( + match parent_pred { + None => format!("`{}`", &p), + Some(parent_pred) => match format_pred(*parent_pred) { + None => format!("`{}`", &p), + Some((parent_p, _)) => { + collect_type_param_suggestions( + self_ty, + *parent_pred, + &p, + ); + format!( + "`{}`\nwhich is required by `{}`", + p, parent_p + ) + } + }, + }, + *pred, + ) + }) + }) + .filter(|(_, pred)| !skip_list.contains(&pred)) + .map(|(t, _)| t) + .enumerate() + .collect::<Vec<(usize, String)>>(); + + for ((span, add_where_or_comma), obligations) in type_params.into_iter() { + restrict_type_params = true; + // #74886: Sort here so that the output is always the same. + let mut obligations = obligations.into_iter().collect::<Vec<_>>(); + obligations.sort(); + err.span_suggestion_verbose( + span, + &format!( + "consider restricting the type parameter{s} to satisfy the \ + trait bound{s}", + s = pluralize!(obligations.len()) + ), + format!("{} {}", add_where_or_comma, obligations.join(", ")), + Applicability::MaybeIncorrect, + ); + } + + bound_list.sort_by(|(_, a), (_, b)| a.cmp(b)); // Sort alphabetically. + bound_list.dedup_by(|(_, a), (_, b)| a == b); // #35677 + bound_list.sort_by_key(|(pos, _)| *pos); // Keep the original predicate order. + + if !bound_list.is_empty() || !skip_list.is_empty() { + let bound_list = bound_list + .into_iter() + .map(|(_, path)| path) + .collect::<Vec<_>>() + .join("\n"); + let actual_prefix = actual.prefix_string(self.tcx); + info!("unimplemented_traits.len() == {}", unimplemented_traits.len()); + let (primary_message, label) = + if unimplemented_traits.len() == 1 && unimplemented_traits_only { + unimplemented_traits + .into_iter() + .next() + .map(|(_, (trait_ref, obligation))| { + if trait_ref.self_ty().references_error() + || actual.references_error() + { + // Avoid crashing. + return (None, None); + } + let OnUnimplementedNote { message, label, .. } = + self.on_unimplemented_note(trait_ref, &obligation); + (message, label) + }) + .unwrap_or((None, None)) + } else { + (None, None) + }; + let primary_message = primary_message.unwrap_or_else(|| format!( + "the {item_kind} `{item_name}` exists for {actual_prefix} `{ty_str}`, but its trait bounds were not satisfied" + )); + err.set_primary_message(&primary_message); + if let Some(label) = label { + custom_span_label = true; + err.span_label(span, label); + } + if !bound_list.is_empty() { + err.note(&format!( + "the following trait bounds were not satisfied:\n{bound_list}" + )); + } + self.suggest_derive(&mut err, &unsatisfied_predicates); + + unsatisfied_bounds = true; + } + } + + let label_span_not_found = |err: &mut DiagnosticBuilder<'_, _>| { + if unsatisfied_predicates.is_empty() { + err.span_label(span, format!("{item_kind} not found in `{ty_str}`")); + let is_string_or_ref_str = match actual.kind() { + ty::Ref(_, ty, _) => { + ty.is_str() + || matches!( + ty.kind(), + ty::Adt(adt, _) if self.tcx.is_diagnostic_item(sym::String, adt.did()) + ) + } + ty::Adt(adt, _) => self.tcx.is_diagnostic_item(sym::String, adt.did()), + _ => false, + }; + if is_string_or_ref_str && item_name.name == sym::iter { + err.span_suggestion_verbose( + item_name.span, + "because of the in-memory representation of `&str`, to obtain \ + an `Iterator` over each of its codepoint use method `chars`", + "chars", + Applicability::MachineApplicable, + ); + } + if let ty::Adt(adt, _) = rcvr_ty.kind() { + let mut inherent_impls_candidate = self + .tcx + .inherent_impls(adt.did()) + .iter() + .copied() + .filter(|def_id| { + if let Some(assoc) = self.associated_value(*def_id, item_name) { + // Check for both mode is the same so we avoid suggesting + // incorrect associated item. + match (mode, assoc.fn_has_self_parameter, source) { + (Mode::MethodCall, true, SelfSource::MethodCall(_)) => { + // We check that the suggest type is actually + // different from the received one + // So we avoid suggestion method with Box<Self> + // for instance + self.tcx.at(span).type_of(*def_id) != actual + && self.tcx.at(span).type_of(*def_id) != rcvr_ty + } + (Mode::Path, false, _) => true, + _ => false, + } + } else { + false + } + }) + .collect::<Vec<_>>(); + if !inherent_impls_candidate.is_empty() { + inherent_impls_candidate.sort(); + inherent_impls_candidate.dedup(); + + // number of type to shows at most. + let limit = if inherent_impls_candidate.len() == 5 { 5 } else { 4 }; + let type_candidates = inherent_impls_candidate + .iter() + .take(limit) + .map(|impl_item| { + format!("- `{}`", self.tcx.at(span).type_of(*impl_item)) + }) + .collect::<Vec<_>>() + .join("\n"); + let additional_types = if inherent_impls_candidate.len() > limit { + format!( + "\nand {} more types", + inherent_impls_candidate.len() - limit + ) + } else { + "".to_string() + }; + err.note(&format!( + "the {item_kind} was found for\n{}{}", + type_candidates, additional_types + )); + } + } + } else { + err.span_label(span, format!("{item_kind} cannot be called on `{ty_str}` due to unsatisfied trait bounds")); + } + }; + + // If the method name is the name of a field with a function or closure type, + // give a helping note that it has to be called as `(x.f)(...)`. + if let SelfSource::MethodCall(expr) = source { + if !self.suggest_field_call(span, rcvr_ty, expr, item_name, &mut err) + && lev_candidate.is_none() + && !custom_span_label + { + label_span_not_found(&mut err); + } + } else if !custom_span_label { + label_span_not_found(&mut err); + } + + self.check_for_field_method(&mut err, source, span, actual, item_name); + + self.check_for_unwrap_self(&mut err, source, span, actual, item_name); + + bound_spans.sort(); + bound_spans.dedup(); + for (span, msg) in bound_spans.into_iter() { + err.span_label(span, &msg); + } + + if actual.is_numeric() && actual.is_fresh() || restrict_type_params { + } else { + self.suggest_traits_to_import( + &mut err, + span, + rcvr_ty, + item_name, + args.map(|args| args.len()), + source, + out_of_scope_traits, + &unsatisfied_predicates, + unsatisfied_bounds, + ); + } + + // Don't emit a suggestion if we found an actual method + // that had unsatisfied trait bounds + if unsatisfied_predicates.is_empty() && actual.is_enum() { + let adt_def = actual.ty_adt_def().expect("enum is not an ADT"); + if let Some(suggestion) = lev_distance::find_best_match_for_name( + &adt_def.variants().iter().map(|s| s.name).collect::<Vec<_>>(), + item_name.name, + None, + ) { + err.span_suggestion( + span, + "there is a variant with a similar name", + suggestion, + Applicability::MaybeIncorrect, + ); + } + } + + if item_name.name == sym::as_str && actual.peel_refs().is_str() { + let msg = "remove this method call"; + let mut fallback_span = true; + if let SelfSource::MethodCall(expr) = source { + let call_expr = + self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)); + if let Some(span) = call_expr.span.trim_start(expr.span) { + err.span_suggestion(span, msg, "", Applicability::MachineApplicable); + fallback_span = false; + } + } + if fallback_span { + err.span_label(span, msg); + } + } else if let Some(lev_candidate) = lev_candidate { + // Don't emit a suggestion if we found an actual method + // that had unsatisfied trait bounds + if unsatisfied_predicates.is_empty() { + let def_kind = lev_candidate.kind.as_def_kind(); + err.span_suggestion( + span, + &format!( + "there is {} {} with a similar name", + def_kind.article(), + def_kind.descr(lev_candidate.def_id), + ), + lev_candidate.name, + Applicability::MaybeIncorrect, + ); + } + } + + return Some(err); + } + + MethodError::Ambiguity(sources) => { + let mut err = struct_span_err!( + self.sess(), + item_name.span, + E0034, + "multiple applicable items in scope" + ); + err.span_label(item_name.span, format!("multiple `{}` found", item_name)); + + report_candidates(span, &mut err, sources, sugg_span); + err.emit(); + } + + MethodError::PrivateMatch(kind, def_id, out_of_scope_traits) => { + let kind = kind.descr(def_id); + let mut err = struct_span_err!( + self.tcx.sess, + item_name.span, + E0624, + "{} `{}` is private", + kind, + item_name + ); + err.span_label(item_name.span, &format!("private {}", kind)); + let sp = self + .tcx + .hir() + .span_if_local(def_id) + .unwrap_or_else(|| self.tcx.def_span(def_id)); + err.span_label(sp, &format!("private {} defined here", kind)); + self.suggest_valid_traits(&mut err, out_of_scope_traits); + err.emit(); + } + + MethodError::IllegalSizedBound(candidates, needs_mut, bound_span) => { + let msg = format!("the `{}` method cannot be invoked on a trait object", item_name); + let mut err = self.sess().struct_span_err(span, &msg); + err.span_label(bound_span, "this has a `Sized` requirement"); + if !candidates.is_empty() { + let help = format!( + "{an}other candidate{s} {were} found in the following trait{s}, perhaps \ + add a `use` for {one_of_them}:", + an = if candidates.len() == 1 { "an" } else { "" }, + s = pluralize!(candidates.len()), + were = pluralize!("was", candidates.len()), + one_of_them = if candidates.len() == 1 { "it" } else { "one_of_them" }, + ); + self.suggest_use_candidates(&mut err, help, candidates); + } + if let ty::Ref(region, t_type, mutability) = rcvr_ty.kind() { + if needs_mut { + let trait_type = self.tcx.mk_ref( + *region, + ty::TypeAndMut { ty: *t_type, mutbl: mutability.invert() }, + ); + err.note(&format!("you need `{}` instead of `{}`", trait_type, rcvr_ty)); + } + } + err.emit(); + } + + MethodError::BadReturnType => bug!("no return type expectations but got BadReturnType"), + } + None + } + + fn suggest_field_call( + &self, + span: Span, + rcvr_ty: Ty<'tcx>, + expr: &hir::Expr<'_>, + item_name: Ident, + err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>, + ) -> bool { + let tcx = self.tcx; + let field_receiver = self.autoderef(span, rcvr_ty).find_map(|(ty, _)| match ty.kind() { + ty::Adt(def, substs) if !def.is_enum() => { + let variant = &def.non_enum_variant(); + tcx.find_field_index(item_name, variant).map(|index| { + let field = &variant.fields[index]; + let field_ty = field.ty(tcx, substs); + (field, field_ty) + }) + } + _ => None, + }); + if let Some((field, field_ty)) = field_receiver { + let scope = tcx.parent_module(self.body_id).to_def_id(); + let is_accessible = field.vis.is_accessible_from(scope, tcx); + + if is_accessible { + if self.is_fn_ty(field_ty, span) { + let expr_span = expr.span.to(item_name.span); + err.multipart_suggestion( + &format!( + "to call the function stored in `{}`, \ + surround the field access with parentheses", + item_name, + ), + vec![ + (expr_span.shrink_to_lo(), '('.to_string()), + (expr_span.shrink_to_hi(), ')'.to_string()), + ], + Applicability::MachineApplicable, + ); + } else { + let call_expr = tcx.hir().expect_expr(tcx.hir().get_parent_node(expr.hir_id)); + + if let Some(span) = call_expr.span.trim_start(item_name.span) { + err.span_suggestion( + span, + "remove the arguments", + "", + Applicability::MaybeIncorrect, + ); + } + } + } + + let field_kind = if is_accessible { "field" } else { "private field" }; + err.span_label(item_name.span, format!("{}, not a method", field_kind)); + return true; + } + false + } + + fn suggest_constraining_numerical_ty( + &self, + tcx: TyCtxt<'tcx>, + actual: Ty<'tcx>, + source: SelfSource<'_>, + span: Span, + item_kind: &str, + item_name: Ident, + ty_str: &str, + ) -> bool { + let found_candidate = all_traits(self.tcx) + .into_iter() + .any(|info| self.associated_value(info.def_id, item_name).is_some()); + let found_assoc = |ty: Ty<'tcx>| { + simplify_type(tcx, ty, TreatParams::AsInfer) + .and_then(|simp| { + tcx.incoherent_impls(simp) + .iter() + .find_map(|&id| self.associated_value(id, item_name)) + }) + .is_some() + }; + let found_candidate = found_candidate + || found_assoc(tcx.types.i8) + || found_assoc(tcx.types.i16) + || found_assoc(tcx.types.i32) + || found_assoc(tcx.types.i64) + || found_assoc(tcx.types.i128) + || found_assoc(tcx.types.u8) + || found_assoc(tcx.types.u16) + || found_assoc(tcx.types.u32) + || found_assoc(tcx.types.u64) + || found_assoc(tcx.types.u128) + || found_assoc(tcx.types.f32) + || found_assoc(tcx.types.f32); + if found_candidate + && actual.is_numeric() + && !actual.has_concrete_skeleton() + && let SelfSource::MethodCall(expr) = source + { + let mut err = struct_span_err!( + tcx.sess, + span, + E0689, + "can't call {} `{}` on ambiguous numeric type `{}`", + item_kind, + item_name, + ty_str + ); + let concrete_type = if actual.is_integral() { "i32" } else { "f32" }; + match expr.kind { + ExprKind::Lit(ref lit) => { + // numeric literal + let snippet = tcx + .sess + .source_map() + .span_to_snippet(lit.span) + .unwrap_or_else(|_| "<numeric literal>".to_owned()); + + // If this is a floating point literal that ends with '.', + // get rid of it to stop this from becoming a member access. + let snippet = snippet.strip_suffix('.').unwrap_or(&snippet); + + err.span_suggestion( + lit.span, + &format!( + "you must specify a concrete type for this numeric value, \ + like `{}`", + concrete_type + ), + format!("{snippet}_{concrete_type}"), + Applicability::MaybeIncorrect, + ); + } + ExprKind::Path(QPath::Resolved(_, path)) => { + // local binding + if let hir::def::Res::Local(hir_id) = path.res { + let span = tcx.hir().span(hir_id); + let snippet = tcx.sess.source_map().span_to_snippet(span); + let filename = tcx.sess.source_map().span_to_filename(span); + + let parent_node = + self.tcx.hir().get(self.tcx.hir().get_parent_node(hir_id)); + let msg = format!( + "you must specify a type for this binding, like `{}`", + concrete_type, + ); + + match (filename, parent_node, snippet) { + ( + FileName::Real(_), + Node::Local(hir::Local { + source: hir::LocalSource::Normal, + ty, + .. + }), + Ok(ref snippet), + ) => { + err.span_suggestion( + // account for `let x: _ = 42;` + // ^^^^ + span.to(ty.as_ref().map(|ty| ty.span).unwrap_or(span)), + &msg, + format!("{}: {}", snippet, concrete_type), + Applicability::MaybeIncorrect, + ); + } + _ => { + err.span_label(span, msg); + } + } + } + } + _ => {} + } + err.emit(); + return true; + } + false + } + + fn check_for_field_method( + &self, + err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>, + source: SelfSource<'tcx>, + span: Span, + actual: Ty<'tcx>, + item_name: Ident, + ) { + if let SelfSource::MethodCall(expr) = source + && let Some((fields, substs)) = self.get_field_candidates(span, actual) + { + let call_expr = self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id)); + for candidate_field in fields.iter() { + if let Some(field_path) = self.check_for_nested_field_satisfying( + span, + &|_, field_ty| { + self.lookup_probe( + span, + item_name, + field_ty, + call_expr, + ProbeScope::AllTraits, + ) + .is_ok() + }, + candidate_field, + substs, + vec![], + self.tcx.parent_module(expr.hir_id).to_def_id(), + ) { + let field_path_str = field_path + .iter() + .map(|id| id.name.to_ident_string()) + .collect::<Vec<String>>() + .join("."); + debug!("field_path_str: {:?}", field_path_str); + + err.span_suggestion_verbose( + item_name.span.shrink_to_lo(), + "one of the expressions' fields has a method of the same name", + format!("{field_path_str}."), + Applicability::MaybeIncorrect, + ); + } + } + } + } + + fn check_for_unwrap_self( + &self, + err: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>, + source: SelfSource<'tcx>, + span: Span, + actual: Ty<'tcx>, + item_name: Ident, + ) { + let tcx = self.tcx; + let SelfSource::MethodCall(expr) = source else { return; }; + let call_expr = tcx.hir().expect_expr(tcx.hir().get_parent_node(expr.hir_id)); + + let ty::Adt(kind, substs) = actual.kind() else { return; }; + if !kind.is_enum() { + return; + } + + let matching_variants: Vec<_> = kind + .variants() + .iter() + .flat_map(|variant| { + let [field] = &variant.fields[..] else { return None; }; + let field_ty = field.ty(tcx, substs); + + // Skip `_`, since that'll just lead to ambiguity. + if self.resolve_vars_if_possible(field_ty).is_ty_var() { + return None; + } + + self.lookup_probe(span, item_name, field_ty, call_expr, ProbeScope::AllTraits) + .ok() + .map(|pick| (variant, field, pick)) + }) + .collect(); + + let ret_ty_matches = |diagnostic_item| { + if let Some(ret_ty) = self + .ret_coercion + .as_ref() + .map(|c| self.resolve_vars_if_possible(c.borrow().expected_ty())) + && let ty::Adt(kind, _) = ret_ty.kind() + && tcx.get_diagnostic_item(diagnostic_item) == Some(kind.did()) + { + true + } else { + false + } + }; + + match &matching_variants[..] { + [(_, field, pick)] => { + let self_ty = field.ty(tcx, substs); + err.span_note( + tcx.def_span(pick.item.def_id), + &format!("the method `{item_name}` exists on the type `{self_ty}`"), + ); + let (article, kind, variant, question) = + if Some(kind.did()) == tcx.get_diagnostic_item(sym::Result) { + ("a", "Result", "Err", ret_ty_matches(sym::Result)) + } else if Some(kind.did()) == tcx.get_diagnostic_item(sym::Option) { + ("an", "Option", "None", ret_ty_matches(sym::Option)) + } else { + return; + }; + if question { + err.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "use the `?` operator to extract the `{self_ty}` value, propagating \ + {article} `{kind}::{variant}` value to the caller" + ), + "?", + Applicability::MachineApplicable, + ); + } else { + err.span_suggestion_verbose( + expr.span.shrink_to_hi(), + format!( + "consider using `{kind}::expect` to unwrap the `{self_ty}` value, \ + panicking if the value is {article} `{kind}::{variant}`" + ), + ".expect(\"REASON\")", + Applicability::HasPlaceholders, + ); + } + } + // FIXME(compiler-errors): Support suggestions for other matching enum variants + _ => {} + } + } + + pub(crate) fn note_unmet_impls_on_type( + &self, + err: &mut Diagnostic, + errors: Vec<FulfillmentError<'tcx>>, + ) { + let all_local_types_needing_impls = + errors.iter().all(|e| match e.obligation.predicate.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => match pred.self_ty().kind() { + ty::Adt(def, _) => def.did().is_local(), + _ => false, + }, + _ => false, + }); + let mut preds: Vec<_> = errors + .iter() + .filter_map(|e| match e.obligation.predicate.kind().skip_binder() { + ty::PredicateKind::Trait(pred) => Some(pred), + _ => None, + }) + .collect(); + preds.sort_by_key(|pred| (pred.def_id(), pred.self_ty())); + let def_ids = preds + .iter() + .filter_map(|pred| match pred.self_ty().kind() { + ty::Adt(def, _) => Some(def.did()), + _ => None, + }) + .collect::<FxHashSet<_>>(); + let mut spans: MultiSpan = def_ids + .iter() + .filter_map(|def_id| { + let span = self.tcx.def_span(*def_id); + if span.is_dummy() { None } else { Some(span) } + }) + .collect::<Vec<_>>() + .into(); + + for pred in &preds { + match pred.self_ty().kind() { + ty::Adt(def, _) if def.did().is_local() => { + spans.push_span_label( + self.tcx.def_span(def.did()), + format!("must implement `{}`", pred.trait_ref.print_only_trait_path()), + ); + } + _ => {} + } + } + + if all_local_types_needing_impls && spans.primary_span().is_some() { + let msg = if preds.len() == 1 { + format!( + "an implementation of `{}` might be missing for `{}`", + preds[0].trait_ref.print_only_trait_path(), + preds[0].self_ty() + ) + } else { + format!( + "the following type{} would have to `impl` {} required trait{} for this \ + operation to be valid", + pluralize!(def_ids.len()), + if def_ids.len() == 1 { "its" } else { "their" }, + pluralize!(preds.len()), + ) + }; + err.span_note(spans, &msg); + } + + let preds: Vec<_> = errors + .iter() + .map(|e| (e.obligation.predicate, None, Some(e.obligation.cause.clone()))) + .collect(); + self.suggest_derive(err, &preds); + } + + fn suggest_derive( + &self, + err: &mut Diagnostic, + unsatisfied_predicates: &[( + ty::Predicate<'tcx>, + Option<ty::Predicate<'tcx>>, + Option<ObligationCause<'tcx>>, + )], + ) { + let mut derives = Vec::<(String, Span, Symbol)>::new(); + let mut traits = Vec::<Span>::new(); + for (pred, _, _) in unsatisfied_predicates { + let ty::PredicateKind::Trait(trait_pred) = pred.kind().skip_binder() else { continue }; + let adt = match trait_pred.self_ty().ty_adt_def() { + Some(adt) if adt.did().is_local() => adt, + _ => continue, + }; + if let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) { + let can_derive = match diagnostic_name { + sym::Default => !adt.is_enum(), + sym::Eq + | sym::PartialEq + | sym::Ord + | sym::PartialOrd + | sym::Clone + | sym::Copy + | sym::Hash + | sym::Debug => true, + _ => false, + }; + if can_derive { + let self_name = trait_pred.self_ty().to_string(); + let self_span = self.tcx.def_span(adt.did()); + if let Some(poly_trait_ref) = pred.to_opt_poly_trait_pred() { + for super_trait in supertraits(self.tcx, poly_trait_ref.to_poly_trait_ref()) + { + if let Some(parent_diagnostic_name) = + self.tcx.get_diagnostic_name(super_trait.def_id()) + { + derives.push(( + self_name.clone(), + self_span, + parent_diagnostic_name, + )); + } + } + } + derives.push((self_name, self_span, diagnostic_name)); + } else { + traits.push(self.tcx.def_span(trait_pred.def_id())); + } + } else { + traits.push(self.tcx.def_span(trait_pred.def_id())); + } + } + traits.sort(); + traits.dedup(); + + derives.sort(); + derives.dedup(); + + let mut derives_grouped = Vec::<(String, Span, String)>::new(); + for (self_name, self_span, trait_name) in derives.into_iter() { + if let Some((last_self_name, _, ref mut last_trait_names)) = derives_grouped.last_mut() + { + if last_self_name == &self_name { + last_trait_names.push_str(format!(", {}", trait_name).as_str()); + continue; + } + } + derives_grouped.push((self_name, self_span, trait_name.to_string())); + } + + let len = traits.len(); + if len > 0 { + let span: MultiSpan = traits.into(); + err.span_note( + span, + &format!("the following trait{} must be implemented", pluralize!(len),), + ); + } + + for (self_name, self_span, traits) in &derives_grouped { + err.span_suggestion_verbose( + self_span.shrink_to_lo(), + &format!("consider annotating `{}` with `#[derive({})]`", self_name, traits), + format!("#[derive({})]\n", traits), + Applicability::MaybeIncorrect, + ); + } + } + + /// Print out the type for use in value namespace. + fn ty_to_value_string(&self, ty: Ty<'tcx>) -> String { + match ty.kind() { + ty::Adt(def, substs) => format!("{}", ty::Instance::new(def.did(), substs)), + _ => self.ty_to_string(ty), + } + } + + fn suggest_await_before_method( + &self, + err: &mut Diagnostic, + item_name: Ident, + ty: Ty<'tcx>, + call: &hir::Expr<'_>, + span: Span, + ) { + let output_ty = match self.get_impl_future_output_ty(ty) { + Some(output_ty) => self.resolve_vars_if_possible(output_ty).skip_binder(), + _ => return, + }; + let method_exists = self.method_exists(item_name, output_ty, call.hir_id, true); + debug!("suggest_await_before_method: is_method_exist={}", method_exists); + if method_exists { + err.span_suggestion_verbose( + span.shrink_to_lo(), + "consider `await`ing on the `Future` and calling the method on its `Output`", + "await.", + Applicability::MaybeIncorrect, + ); + } + } + + fn suggest_use_candidates(&self, err: &mut Diagnostic, msg: String, candidates: Vec<DefId>) { + let parent_map = self.tcx.visible_parent_map(()); + + // Separate out candidates that must be imported with a glob, because they are named `_` + // and cannot be referred with their identifier. + let (candidates, globs): (Vec<_>, Vec<_>) = candidates.into_iter().partition(|trait_did| { + if let Some(parent_did) = parent_map.get(trait_did) { + // If the item is re-exported as `_`, we should suggest a glob-import instead. + if *parent_did != self.tcx.parent(*trait_did) + && self + .tcx + .module_children(*parent_did) + .iter() + .filter(|child| child.res.opt_def_id() == Some(*trait_did)) + .all(|child| child.ident.name == kw::Underscore) + { + return false; + } + } + + true + }); + + let module_did = self.tcx.parent_module(self.body_id); + let (module, _, _) = self.tcx.hir().get_module(module_did); + let span = module.spans.inject_use_span; + + let path_strings = candidates.iter().map(|trait_did| { + format!("use {};\n", with_crate_prefix!(self.tcx.def_path_str(*trait_did)),) + }); + + let glob_path_strings = globs.iter().map(|trait_did| { + let parent_did = parent_map.get(trait_did).unwrap(); + format!( + "use {}::*; // trait {}\n", + with_crate_prefix!(self.tcx.def_path_str(*parent_did)), + self.tcx.item_name(*trait_did), + ) + }); + + err.span_suggestions( + span, + &msg, + path_strings.chain(glob_path_strings), + Applicability::MaybeIncorrect, + ); + } + + fn suggest_valid_traits( + &self, + err: &mut Diagnostic, + valid_out_of_scope_traits: Vec<DefId>, + ) -> bool { + if !valid_out_of_scope_traits.is_empty() { + let mut candidates = valid_out_of_scope_traits; + candidates.sort(); + candidates.dedup(); + + // `TryFrom` and `FromIterator` have no methods + let edition_fix = candidates + .iter() + .find(|did| self.tcx.is_diagnostic_item(sym::TryInto, **did)) + .copied(); + + err.help("items from traits can only be used if the trait is in scope"); + let msg = format!( + "the following {traits_are} implemented but not in scope; \ + perhaps add a `use` for {one_of_them}:", + traits_are = if candidates.len() == 1 { "trait is" } else { "traits are" }, + one_of_them = if candidates.len() == 1 { "it" } else { "one of them" }, + ); + + self.suggest_use_candidates(err, msg, candidates); + if let Some(did) = edition_fix { + err.note(&format!( + "'{}' is included in the prelude starting in Edition 2021", + with_crate_prefix!(self.tcx.def_path_str(did)) + )); + } + + true + } else { + false + } + } + + fn suggest_traits_to_import( + &self, + err: &mut Diagnostic, + span: Span, + rcvr_ty: Ty<'tcx>, + item_name: Ident, + inputs_len: Option<usize>, + source: SelfSource<'tcx>, + valid_out_of_scope_traits: Vec<DefId>, + unsatisfied_predicates: &[( + ty::Predicate<'tcx>, + Option<ty::Predicate<'tcx>>, + Option<ObligationCause<'tcx>>, + )], + unsatisfied_bounds: bool, + ) { + let mut alt_rcvr_sugg = false; + if let (SelfSource::MethodCall(rcvr), false) = (source, unsatisfied_bounds) { + debug!(?span, ?item_name, ?rcvr_ty, ?rcvr); + let skippable = [ + self.tcx.lang_items().clone_trait(), + self.tcx.lang_items().deref_trait(), + self.tcx.lang_items().deref_mut_trait(), + self.tcx.lang_items().drop_trait(), + self.tcx.get_diagnostic_item(sym::AsRef), + ]; + // Try alternative arbitrary self types that could fulfill this call. + // FIXME: probe for all types that *could* be arbitrary self-types, not + // just this list. + for (rcvr_ty, post) in &[ + (rcvr_ty, ""), + (self.tcx.mk_mut_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&mut "), + (self.tcx.mk_imm_ref(self.tcx.lifetimes.re_erased, rcvr_ty), "&"), + ] { + match self.lookup_probe(span, item_name, *rcvr_ty, rcvr, ProbeScope::AllTraits) { + Ok(pick) => { + // If the method is defined for the receiver we have, it likely wasn't `use`d. + // We point at the method, but we just skip the rest of the check for arbitrary + // self types and rely on the suggestion to `use` the trait from + // `suggest_valid_traits`. + let did = Some(pick.item.container_id(self.tcx)); + let skip = skippable.contains(&did); + if pick.autoderefs == 0 && !skip { + err.span_label( + pick.item.ident(self.tcx).span, + &format!("the method is available for `{}` here", rcvr_ty), + ); + } + break; + } + Err(MethodError::Ambiguity(_)) => { + // If the method is defined (but ambiguous) for the receiver we have, it is also + // likely we haven't `use`d it. It may be possible that if we `Box`/`Pin`/etc. + // the receiver, then it might disambiguate this method, but I think these + // suggestions are generally misleading (see #94218). + break; + } + _ => {} + } + + for (rcvr_ty, pre) in &[ + (self.tcx.mk_lang_item(*rcvr_ty, LangItem::OwnedBox), "Box::new"), + (self.tcx.mk_lang_item(*rcvr_ty, LangItem::Pin), "Pin::new"), + (self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Arc), "Arc::new"), + (self.tcx.mk_diagnostic_item(*rcvr_ty, sym::Rc), "Rc::new"), + ] { + if let Some(new_rcvr_t) = *rcvr_ty + && let Ok(pick) = self.lookup_probe( + span, + item_name, + new_rcvr_t, + rcvr, + ProbeScope::AllTraits, + ) + { + debug!("try_alt_rcvr: pick candidate {:?}", pick); + let did = Some(pick.item.container_id(self.tcx)); + // We don't want to suggest a container type when the missing + // method is `.clone()` or `.deref()` otherwise we'd suggest + // `Arc::new(foo).clone()`, which is far from what the user wants. + // Explicitly ignore the `Pin::as_ref()` method as `Pin` does not + // implement the `AsRef` trait. + let skip = skippable.contains(&did) + || (("Pin::new" == *pre) && (sym::as_ref == item_name.name)) + || inputs_len.map_or(false, |inputs_len| pick.item.kind == ty::AssocKind::Fn && self.tcx.fn_sig(pick.item.def_id).skip_binder().inputs().len() != inputs_len); + // Make sure the method is defined for the *actual* receiver: we don't + // want to treat `Box<Self>` as a receiver if it only works because of + // an autoderef to `&self` + if pick.autoderefs == 0 && !skip { + err.span_label( + pick.item.ident(self.tcx).span, + &format!("the method is available for `{}` here", new_rcvr_t), + ); + err.multipart_suggestion( + "consider wrapping the receiver expression with the \ + appropriate type", + vec![ + (rcvr.span.shrink_to_lo(), format!("{}({}", pre, post)), + (rcvr.span.shrink_to_hi(), ")".to_string()), + ], + Applicability::MaybeIncorrect, + ); + // We don't care about the other suggestions. + alt_rcvr_sugg = true; + } + } + } + } + } + if self.suggest_valid_traits(err, valid_out_of_scope_traits) { + return; + } + + let type_is_local = self.type_derefs_to_local(span, rcvr_ty, source); + + let mut arbitrary_rcvr = vec![]; + // There are no traits implemented, so lets suggest some traits to + // implement, by finding ones that have the item name, and are + // legal to implement. + let mut candidates = all_traits(self.tcx) + .into_iter() + // Don't issue suggestions for unstable traits since they're + // unlikely to be implementable anyway + .filter(|info| match self.tcx.lookup_stability(info.def_id) { + Some(attr) => attr.level.is_stable(), + None => true, + }) + .filter(|info| { + // We approximate the coherence rules to only suggest + // traits that are legal to implement by requiring that + // either the type or trait is local. Multi-dispatch means + // this isn't perfect (that is, there are cases when + // implementing a trait would be legal but is rejected + // here). + unsatisfied_predicates.iter().all(|(p, _, _)| { + match p.kind().skip_binder() { + // Hide traits if they are present in predicates as they can be fixed without + // having to implement them. + ty::PredicateKind::Trait(t) => t.def_id() == info.def_id, + ty::PredicateKind::Projection(p) => { + p.projection_ty.item_def_id == info.def_id + } + _ => false, + } + }) && (type_is_local || info.def_id.is_local()) + && self + .associated_value(info.def_id, item_name) + .filter(|item| { + if let ty::AssocKind::Fn = item.kind { + let id = item + .def_id + .as_local() + .map(|def_id| self.tcx.hir().local_def_id_to_hir_id(def_id)); + if let Some(hir::Node::TraitItem(hir::TraitItem { + kind: hir::TraitItemKind::Fn(fn_sig, method), + .. + })) = id.map(|id| self.tcx.hir().get(id)) + { + let self_first_arg = match method { + hir::TraitFn::Required([ident, ..]) => { + ident.name == kw::SelfLower + } + hir::TraitFn::Provided(body_id) => { + self.tcx.hir().body(*body_id).params.first().map_or( + false, + |param| { + matches!( + param.pat.kind, + hir::PatKind::Binding(_, _, ident, _) + if ident.name == kw::SelfLower + ) + }, + ) + } + _ => false, + }; + + if !fn_sig.decl.implicit_self.has_implicit_self() + && self_first_arg + { + if let Some(ty) = fn_sig.decl.inputs.get(0) { + arbitrary_rcvr.push(ty.span); + } + return false; + } + } + } + // We only want to suggest public or local traits (#45781). + item.visibility(self.tcx).is_public() || info.def_id.is_local() + }) + .is_some() + }) + .collect::<Vec<_>>(); + for span in &arbitrary_rcvr { + err.span_label( + *span, + "the method might not be found because of this arbitrary self type", + ); + } + if alt_rcvr_sugg { + return; + } + + if !candidates.is_empty() { + // Sort from most relevant to least relevant. + candidates.sort_by(|a, b| a.cmp(b).reverse()); + candidates.dedup(); + + let param_type = match rcvr_ty.kind() { + ty::Param(param) => Some(param), + ty::Ref(_, ty, _) => match ty.kind() { + ty::Param(param) => Some(param), + _ => None, + }, + _ => None, + }; + err.help(if param_type.is_some() { + "items from traits can only be used if the type parameter is bounded by the trait" + } else { + "items from traits can only be used if the trait is implemented and in scope" + }); + let candidates_len = candidates.len(); + let message = |action| { + format!( + "the following {traits_define} an item `{name}`, perhaps you need to {action} \ + {one_of_them}:", + traits_define = + if candidates_len == 1 { "trait defines" } else { "traits define" }, + action = action, + one_of_them = if candidates_len == 1 { "it" } else { "one of them" }, + name = item_name, + ) + }; + // Obtain the span for `param` and use it for a structured suggestion. + if let Some(param) = param_type { + let generics = self.tcx.generics_of(self.body_id.owner.to_def_id()); + let type_param = generics.type_param(param, self.tcx); + let hir = self.tcx.hir(); + if let Some(def_id) = type_param.def_id.as_local() { + let id = hir.local_def_id_to_hir_id(def_id); + // Get the `hir::Param` to verify whether it already has any bounds. + // We do this to avoid suggesting code that ends up as `T: FooBar`, + // instead we suggest `T: Foo + Bar` in that case. + match hir.get(id) { + Node::GenericParam(param) => { + enum Introducer { + Plus, + Colon, + Nothing, + } + let ast_generics = hir.get_generics(id.owner).unwrap(); + let (sp, mut introducer) = if let Some(span) = + ast_generics.bounds_span_for_suggestions(def_id) + { + (span, Introducer::Plus) + } else if let Some(colon_span) = param.colon_span { + (colon_span.shrink_to_hi(), Introducer::Nothing) + } else { + (param.span.shrink_to_hi(), Introducer::Colon) + }; + if matches!( + param.kind, + hir::GenericParamKind::Type { synthetic: true, .. }, + ) { + introducer = Introducer::Plus + } + let trait_def_ids: FxHashSet<DefId> = ast_generics + .bounds_for_param(def_id) + .flat_map(|bp| bp.bounds.iter()) + .filter_map(|bound| bound.trait_ref()?.trait_def_id()) + .collect(); + if !candidates.iter().any(|t| trait_def_ids.contains(&t.def_id)) { + err.span_suggestions( + sp, + &message(format!( + "restrict type parameter `{}` with", + param.name.ident(), + )), + candidates.iter().map(|t| { + format!( + "{} {}", + match introducer { + Introducer::Plus => " +", + Introducer::Colon => ":", + Introducer::Nothing => "", + }, + self.tcx.def_path_str(t.def_id), + ) + }), + Applicability::MaybeIncorrect, + ); + } + return; + } + Node::Item(hir::Item { + kind: hir::ItemKind::Trait(.., bounds, _), + ident, + .. + }) => { + let (sp, sep, article) = if bounds.is_empty() { + (ident.span.shrink_to_hi(), ":", "a") + } else { + (bounds.last().unwrap().span().shrink_to_hi(), " +", "another") + }; + err.span_suggestions( + sp, + &message(format!("add {} supertrait for", article)), + candidates.iter().map(|t| { + format!("{} {}", sep, self.tcx.def_path_str(t.def_id),) + }), + Applicability::MaybeIncorrect, + ); + return; + } + _ => {} + } + } + } + + let (potential_candidates, explicitly_negative) = if param_type.is_some() { + // FIXME: Even though negative bounds are not implemented, we could maybe handle + // cases where a positive bound implies a negative impl. + (candidates, Vec::new()) + } else if let Some(simp_rcvr_ty) = + simplify_type(self.tcx, rcvr_ty, TreatParams::AsPlaceholder) + { + let mut potential_candidates = Vec::new(); + let mut explicitly_negative = Vec::new(); + for candidate in candidates { + // Check if there's a negative impl of `candidate` for `rcvr_ty` + if self + .tcx + .all_impls(candidate.def_id) + .filter(|imp_did| { + self.tcx.impl_polarity(*imp_did) == ty::ImplPolarity::Negative + }) + .any(|imp_did| { + let imp = self.tcx.impl_trait_ref(imp_did).unwrap(); + let imp_simp = + simplify_type(self.tcx, imp.self_ty(), TreatParams::AsPlaceholder); + imp_simp.map_or(false, |s| s == simp_rcvr_ty) + }) + { + explicitly_negative.push(candidate); + } else { + potential_candidates.push(candidate); + } + } + (potential_candidates, explicitly_negative) + } else { + // We don't know enough about `recv_ty` to make proper suggestions. + (candidates, Vec::new()) + }; + + let action = if let Some(param) = param_type { + format!("restrict type parameter `{}` with", param) + } else { + // FIXME: it might only need to be imported into scope, not implemented. + "implement".to_string() + }; + match &potential_candidates[..] { + [] => {} + [trait_info] if trait_info.def_id.is_local() => { + err.span_note( + self.tcx.def_span(trait_info.def_id), + &format!( + "`{}` defines an item `{}`, perhaps you need to {} it", + self.tcx.def_path_str(trait_info.def_id), + item_name, + action + ), + ); + } + trait_infos => { + let mut msg = message(action); + for (i, trait_info) in trait_infos.iter().enumerate() { + msg.push_str(&format!( + "\ncandidate #{}: `{}`", + i + 1, + self.tcx.def_path_str(trait_info.def_id), + )); + } + err.note(&msg); + } + } + match &explicitly_negative[..] { + [] => {} + [trait_info] => { + let msg = format!( + "the trait `{}` defines an item `{}`, but is explicitly unimplemented", + self.tcx.def_path_str(trait_info.def_id), + item_name + ); + err.note(&msg); + } + trait_infos => { + let mut msg = format!( + "the following traits define an item `{}`, but are explicitly unimplemented:", + item_name + ); + for trait_info in trait_infos { + msg.push_str(&format!("\n{}", self.tcx.def_path_str(trait_info.def_id))); + } + err.note(&msg); + } + } + } + } + + /// Checks whether there is a local type somewhere in the chain of + /// autoderefs of `rcvr_ty`. + fn type_derefs_to_local( + &self, + span: Span, + rcvr_ty: Ty<'tcx>, + source: SelfSource<'tcx>, + ) -> bool { + fn is_local(ty: Ty<'_>) -> bool { + match ty.kind() { + ty::Adt(def, _) => def.did().is_local(), + ty::Foreign(did) => did.is_local(), + ty::Dynamic(tr, ..) => tr.principal().map_or(false, |d| d.def_id().is_local()), + ty::Param(_) => true, + + // Everything else (primitive types, etc.) is effectively + // non-local (there are "edge" cases, e.g., `(LocalType,)`, but + // the noise from these sort of types is usually just really + // annoying, rather than any sort of help). + _ => false, + } + } + + // This occurs for UFCS desugaring of `T::method`, where there is no + // receiver expression for the method call, and thus no autoderef. + if let SelfSource::QPath(_) = source { + return is_local(self.resolve_vars_with_obligations(rcvr_ty)); + } + + self.autoderef(span, rcvr_ty).any(|(ty, _)| is_local(ty)) + } +} + +#[derive(Copy, Clone, Debug)] +pub enum SelfSource<'a> { + QPath(&'a hir::Ty<'a>), + MethodCall(&'a hir::Expr<'a> /* rcvr */), +} + +#[derive(Copy, Clone)] +pub struct TraitInfo { + pub def_id: DefId, +} + +impl PartialEq for TraitInfo { + fn eq(&self, other: &TraitInfo) -> bool { + self.cmp(other) == Ordering::Equal + } +} +impl Eq for TraitInfo {} +impl PartialOrd for TraitInfo { + fn partial_cmp(&self, other: &TraitInfo) -> Option<Ordering> { + Some(self.cmp(other)) + } +} +impl Ord for TraitInfo { + fn cmp(&self, other: &TraitInfo) -> Ordering { + // Local crates are more important than remote ones (local: + // `cnum == 0`), and otherwise we throw in the defid for totality. + + let lhs = (other.def_id.krate, other.def_id); + let rhs = (self.def_id.krate, self.def_id); + lhs.cmp(&rhs) + } +} + +/// Retrieves all traits in this crate and any dependent crates, +/// and wraps them into `TraitInfo` for custom sorting. +pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> { + tcx.all_traits().map(|def_id| TraitInfo { def_id }).collect() +} + +fn print_disambiguation_help<'tcx>( + item_name: Ident, + args: Option<&'tcx [hir::Expr<'tcx>]>, + err: &mut Diagnostic, + trait_name: String, + rcvr_ty: Ty<'_>, + kind: ty::AssocKind, + def_id: DefId, + span: Span, + candidate: Option<usize>, + source_map: &source_map::SourceMap, + fn_has_self_parameter: bool, +) { + let mut applicability = Applicability::MachineApplicable; + let (span, sugg) = if let (ty::AssocKind::Fn, Some(args)) = (kind, args) { + let args = format!( + "({}{})", + if rcvr_ty.is_region_ptr() { + if rcvr_ty.is_mutable_ptr() { "&mut " } else { "&" } + } else { + "" + }, + args.iter() + .map(|arg| source_map.span_to_snippet(arg.span).unwrap_or_else(|_| { + applicability = Applicability::HasPlaceholders; + "_".to_owned() + })) + .collect::<Vec<_>>() + .join(", "), + ); + let trait_name = if !fn_has_self_parameter { + format!("<{} as {}>", rcvr_ty, trait_name) + } else { + trait_name + }; + (span, format!("{}::{}{}", trait_name, item_name, args)) + } else { + (span.with_hi(item_name.span.lo()), format!("<{} as {}>::", rcvr_ty, trait_name)) + }; + err.span_suggestion_verbose( + span, + &format!( + "disambiguate the {} for {}", + kind.as_def_kind().descr(def_id), + if let Some(candidate) = candidate { + format!("candidate #{}", candidate) + } else { + "the candidate".to_string() + }, + ), + sugg, + applicability, + ); +} |