3 use rustc_ast::{self as ast, Path};
4 use rustc_ast_pretty::pprust;
5 use rustc_data_structures::fx::FxHashSet;
7 struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan,
9 use rustc_feature::BUILTIN_ATTRIBUTES;
10 use rustc_hir::def::Namespace::{self, *};
11 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
12 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
13 use rustc_hir::PrimTy;
14 use rustc_middle::bug;
15 use rustc_middle::ty::DefIdTree;
16 use rustc_session::Session;
17 use rustc_span::hygiene::MacroKind;
18 use rustc_span::lev_distance::find_best_match_for_name;
19 use rustc_span::source_map::SourceMap;
20 use rustc_span::symbol::{kw, sym, Ident, Symbol};
21 use rustc_span::{BytePos, Span};
24 use crate::imports::{Import, ImportKind, ImportResolver};
25 use crate::path_names_to_string;
26 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
27 use crate::{BindingError, HasGenericParams, MacroRulesScope, Module, ModuleOrUniformRoot};
28 use crate::{Finalize, NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
29 use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment};
31 type Res = def::Res<ast::NodeId>;
33 /// A vector of spans and replacements, a message and applicability.
34 crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
36 /// Potential candidate for an undeclared or out-of-scope label - contains the ident of a
37 /// similarly named label and whether or not it is reachable.
38 crate type LabelSuggestion = (Ident, bool);
40 crate enum SuggestionTarget {
41 /// The target has a similar name as the name used by the programmer (probably a typo)
43 /// The target is the only valid item that can be used in the corresponding context
47 crate struct TypoSuggestion {
48 pub candidate: Symbol,
50 pub target: SuggestionTarget,
54 crate fn typo_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
55 Self { candidate, res, target: SuggestionTarget::SimilarlyNamed }
57 crate fn single_item_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
58 Self { candidate, res, target: SuggestionTarget::SingleItem }
62 /// A free importable items suggested in case of resolution failure.
63 crate struct ImportSuggestion {
64 pub did: Option<DefId>,
65 pub descr: &'static str,
68 /// An extra note that should be issued if this item is suggested
69 pub note: Option<String>,
72 /// Adjust the impl span so that just the `impl` keyword is taken by removing
73 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
74 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
76 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
77 /// parser. If you need to use this function or something similar, please consider updating the
78 /// `source_map` functions and this function to something more robust.
79 fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
80 let impl_span = sm.span_until_char(impl_span, '<');
81 sm.span_until_whitespace(impl_span)
84 impl<'a> Resolver<'a> {
85 crate fn add_module_candidates(
88 names: &mut Vec<TypoSuggestion>,
89 filter_fn: &impl Fn(Res) -> bool,
91 for (key, resolution) in self.resolutions(module).borrow().iter() {
92 if let Some(binding) = resolution.borrow().binding {
93 let res = binding.res();
95 names.push(TypoSuggestion::typo_from_res(key.ident.name, res));
101 /// Combines an error with provided span and emits it.
103 /// This takes the error provided, combines it with the span and any additional spans inside the
104 /// error and emits it.
105 crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
106 self.into_struct_error(span, resolution_error).emit();
109 crate fn into_struct_error(
112 resolution_error: ResolutionError<'_>,
113 ) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
114 match resolution_error {
115 ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
116 let mut err = struct_span_err!(
120 "can't use generic parameters from outer function",
122 err.span_label(span, "use of generic parameter from outer function".to_string());
124 let sm = self.session.source_map();
126 Res::SelfTy { trait_: maybe_trait_defid, alias_to: maybe_impl_defid } => {
127 if let Some(impl_span) =
128 maybe_impl_defid.and_then(|(def_id, _)| self.opt_span(def_id))
131 reduce_impl_span_to_impl_keyword(sm, impl_span),
132 "`Self` type implicitly declared here, by this `impl`",
135 match (maybe_trait_defid, maybe_impl_defid) {
137 err.span_label(span, "can't use `Self` here");
140 err.span_label(span, "use a type here instead");
142 (None, None) => bug!("`impl` without trait nor type?"),
146 Res::Def(DefKind::TyParam, def_id) => {
147 if let Some(span) = self.opt_span(def_id) {
148 err.span_label(span, "type parameter from outer function");
151 Res::Def(DefKind::ConstParam, def_id) => {
152 if let Some(span) = self.opt_span(def_id) {
153 err.span_label(span, "const parameter from outer function");
158 "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
159 DefKind::TyParam or DefKind::ConstParam"
164 if has_generic_params == HasGenericParams::Yes {
165 // Try to retrieve the span of the function signature and generate a new
166 // message with a local type or const parameter.
167 let sugg_msg = "try using a local generic parameter instead";
168 if let Some((sugg_span, snippet)) = sm.generate_local_type_param_snippet(span) {
169 // Suggest the modification to the user
174 Applicability::MachineApplicable,
176 } else if let Some(sp) = sm.generate_fn_name_span(span) {
179 "try adding a local generic parameter in this method instead"
183 err.help("try using a local generic parameter instead");
189 ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
190 let mut err = struct_span_err!(
194 "the name `{}` is already used for a generic \
195 parameter in this item's generic parameters",
198 err.span_label(span, "already used");
199 err.span_label(first_use_span, format!("first use of `{}`", name));
202 ResolutionError::MethodNotMemberOfTrait(method, trait_, candidate) => {
203 let mut err = struct_span_err!(
207 "method `{}` is not a member of trait `{}`",
211 err.span_label(span, format!("not a member of trait `{}`", trait_));
212 if let Some(candidate) = candidate {
215 "there is an associated function with a similar name",
216 candidate.to_ident_string(),
217 Applicability::MaybeIncorrect,
222 ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => {
223 let mut err = struct_span_err!(
227 "type `{}` is not a member of trait `{}`",
231 err.span_label(span, format!("not a member of trait `{}`", trait_));
232 if let Some(candidate) = candidate {
235 "there is an associated type with a similar name",
236 candidate.to_ident_string(),
237 Applicability::MaybeIncorrect,
242 ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => {
243 let mut err = struct_span_err!(
247 "const `{}` is not a member of trait `{}`",
251 err.span_label(span, format!("not a member of trait `{}`", trait_));
252 if let Some(candidate) = candidate {
255 "there is an associated constant with a similar name",
256 candidate.to_ident_string(),
257 Applicability::MaybeIncorrect,
262 ResolutionError::VariableNotBoundInPattern(binding_error) => {
263 let BindingError { name, target, origin, could_be_path } = binding_error;
265 let target_sp = target.iter().copied().collect::<Vec<_>>();
266 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
268 let msp = MultiSpan::from_spans(target_sp.clone());
269 let mut err = struct_span_err!(
273 "variable `{}` is not bound in all patterns",
276 for sp in target_sp {
277 err.span_label(sp, format!("pattern doesn't bind `{}`", name));
279 for sp in origin_sp {
280 err.span_label(sp, "variable not in all patterns");
283 let help_msg = format!(
284 "if you meant to match on a variant or a `const` item, consider \
285 making the path in the pattern qualified: `?::{}`",
288 err.span_help(span, &help_msg);
292 ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
293 let mut err = struct_span_err!(
297 "variable `{}` is bound inconsistently across alternatives separated by `|`",
300 err.span_label(span, "bound in different ways");
301 err.span_label(first_binding_span, "first binding");
304 ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
305 let mut err = struct_span_err!(
309 "identifier `{}` is bound more than once in this parameter list",
312 err.span_label(span, "used as parameter more than once");
315 ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
316 let mut err = struct_span_err!(
320 "identifier `{}` is bound more than once in the same pattern",
323 err.span_label(span, "used in a pattern more than once");
326 ResolutionError::UndeclaredLabel { name, suggestion } => {
327 let mut err = struct_span_err!(
331 "use of undeclared label `{}`",
335 err.span_label(span, format!("undeclared label `{}`", name));
338 // A reachable label with a similar name exists.
339 Some((ident, true)) => {
340 err.span_label(ident.span, "a label with a similar name is reachable");
343 "try using similarly named label",
344 ident.name.to_string(),
345 Applicability::MaybeIncorrect,
348 // An unreachable label with a similar name exists.
349 Some((ident, false)) => {
352 "a label with a similar name exists but is unreachable",
355 // No similarly-named labels exist.
361 ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
362 let mut err = struct_span_err!(
367 "`self` imports are only allowed within a { } list"
370 // None of the suggestions below would help with a case like `use self`.
372 // use foo::bar::self -> foo::bar
373 // use foo::bar::self as abc -> foo::bar as abc
376 "consider importing the module directly",
378 Applicability::MachineApplicable,
381 // use foo::bar::self -> foo::bar::{self}
382 // use foo::bar::self as abc -> foo::bar::{self as abc}
384 (span_with_rename.shrink_to_lo(), "{".to_string()),
385 (span_with_rename.shrink_to_hi(), "}".to_string()),
387 err.multipart_suggestion(
388 "alternatively, use the multi-path `use` syntax to import `self`",
390 Applicability::MachineApplicable,
395 ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
396 let mut err = struct_span_err!(
400 "`self` import can only appear once in an import list"
402 err.span_label(span, "can only appear once in an import list");
405 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
406 let mut err = struct_span_err!(
410 "`self` import can only appear in an import list with \
413 err.span_label(span, "can only appear in an import list with a non-empty prefix");
416 ResolutionError::FailedToResolve { label, suggestion } => {
418 struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
419 err.span_label(span, label);
421 if let Some((suggestions, msg, applicability)) = suggestion {
422 if suggestions.is_empty() {
426 err.multipart_suggestion(&msg, suggestions, applicability);
431 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
432 let mut err = struct_span_err!(
437 "can't capture dynamic environment in a fn item"
439 err.help("use the `|| { ... }` closure form instead");
442 ResolutionError::AttemptToUseNonConstantValueInConstant(ident, sugg, current) => {
443 let mut err = struct_span_err!(
447 "attempt to use a non-constant value in a constant"
450 // ^^^ given this Span
451 // ------- get this Span to have an applicable suggestion
454 // only do this if the const and usage of the non-constant value are on the same line
455 // the further the two are apart, the higher the chance of the suggestion being wrong
460 .span_extend_to_prev_str(ident.span, current, true, false);
463 Some(sp) if !self.session.source_map().is_multiline(sp) => {
464 let sp = sp.with_lo(BytePos(sp.lo().0 - (current.len() as u32)));
467 &format!("consider using `{}` instead of `{}`", sugg, current),
468 format!("{} {}", sugg, ident),
469 Applicability::MaybeIncorrect,
471 err.span_label(span, "non-constant value");
474 err.span_label(ident.span, &format!("this would need to be a `{}`", sugg));
480 ResolutionError::BindingShadowsSomethingUnacceptable {
481 shadowing_binding_descr,
485 shadowed_binding_descr,
486 shadowed_binding_span,
488 let mut err = struct_span_err!(
492 "{}s cannot shadow {}s",
493 shadowing_binding_descr,
494 shadowed_binding_descr,
498 format!("cannot be named the same as {} {}", article, shadowed_binding_descr),
501 format!("the {} `{}` is {} here", shadowed_binding_descr, name, participle);
502 err.span_label(shadowed_binding_span, msg);
505 ResolutionError::ForwardDeclaredGenericParam => {
506 let mut err = struct_span_err!(
510 "generic parameters with a default cannot use \
511 forward declared identifiers"
515 "defaulted generic parameters cannot be forward declared".to_string(),
519 ResolutionError::ParamInTyOfConstParam(name) => {
520 let mut err = struct_span_err!(
524 "the type of const parameters must not depend on other generic parameters"
528 format!("the type must not depend on the parameter `{}`", name),
532 ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
533 let mut err = self.session.struct_span_err(
535 "generic parameters may not be used in const operations",
537 err.span_label(span, &format!("cannot perform const operation using `{}`", name));
540 err.note("type parameters may not be used in const expressions");
543 "const parameters may only be used as standalone arguments, i.e. `{}`",
548 if self.session.is_nightly_build() {
550 "use `#![feature(generic_const_exprs)]` to allow generic const expressions",
556 ResolutionError::SelfInGenericParamDefault => {
557 let mut err = struct_span_err!(
561 "generic parameters cannot use `Self` in their defaults"
563 err.span_label(span, "`Self` in generic parameter default".to_string());
566 ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
567 let mut err = struct_span_err!(
571 "use of unreachable label `{}`",
575 err.span_label(definition_span, "unreachable label defined here");
576 err.span_label(span, format!("unreachable label `{}`", name));
578 "labels are unreachable through functions, closures, async blocks and modules",
582 // A reachable label with a similar name exists.
583 Some((ident, true)) => {
584 err.span_label(ident.span, "a label with a similar name is reachable");
587 "try using similarly named label",
588 ident.name.to_string(),
589 Applicability::MaybeIncorrect,
592 // An unreachable label with a similar name exists.
593 Some((ident, false)) => {
596 "a label with a similar name exists but is also unreachable",
599 // No similarly-named labels exist.
605 ResolutionError::TraitImplMismatch {
612 let mut err = self.session.struct_span_err_with_code(
615 "item `{}` is an associated {}, which doesn't match its trait `{}`",
616 name, kind, trait_path,
620 err.span_label(span, "does not match trait");
621 err.span_label(trait_item_span, "item in trait");
627 crate fn report_vis_error(
629 vis_resolution_error: VisResolutionError<'_>,
630 ) -> ErrorGuaranteed {
631 match vis_resolution_error {
632 VisResolutionError::Relative2018(span, path) => {
633 let mut err = self.session.struct_span_err(
635 "relative paths are not supported in visibilities on 2018 edition",
640 format!("crate::{}", pprust::path_to_string(&path)),
641 Applicability::MaybeIncorrect,
645 VisResolutionError::AncestorOnly(span) => struct_span_err!(
649 "visibilities can only be restricted to ancestor modules"
651 VisResolutionError::FailedToResolve(span, label, suggestion) => {
652 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
654 VisResolutionError::ExpectedFound(span, path_str, res) => {
655 let mut err = struct_span_err!(
659 "expected module, found {} `{}`",
663 err.span_label(span, "not a module");
666 VisResolutionError::Indeterminate(span) => struct_span_err!(
670 "cannot determine resolution for the visibility"
672 VisResolutionError::ModuleOnly(span) => {
673 self.session.struct_span_err(span, "visibility must resolve to a module")
679 /// Lookup typo candidate in scope for a macro or import.
680 fn early_lookup_typo_candidate(
682 scope_set: ScopeSet<'a>,
683 parent_scope: &ParentScope<'a>,
685 filter_fn: &impl Fn(Res) -> bool,
686 ) -> Option<TypoSuggestion> {
687 let mut suggestions = Vec::new();
688 let ctxt = ident.span.ctxt();
689 self.visit_scopes(scope_set, parent_scope, ctxt, |this, scope, use_prelude, _| {
691 Scope::DeriveHelpers(expn_id) => {
692 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
699 .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
703 Scope::DeriveHelpersCompat => {
704 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
706 for derive in parent_scope.derives {
707 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
708 if let Ok((Some(ext), _)) = this.resolve_macro_path(
710 Some(MacroKind::Derive),
718 .map(|name| TypoSuggestion::typo_from_res(*name, res)),
724 Scope::MacroRules(macro_rules_scope) => {
725 if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
726 let res = macro_rules_binding.binding.res();
728 suggestions.push(TypoSuggestion::typo_from_res(
729 macro_rules_binding.ident.name,
735 Scope::CrateRoot => {
736 let root_ident = Ident::new(kw::PathRoot, ident.span);
737 let root_module = this.resolve_crate_root(root_ident);
738 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
740 Scope::Module(module, _) => {
741 this.add_module_candidates(module, &mut suggestions, filter_fn);
743 Scope::RegisteredAttrs => {
744 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
747 this.registered_attrs
749 .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
753 Scope::MacroUsePrelude => {
754 suggestions.extend(this.macro_use_prelude.iter().filter_map(
756 let res = binding.res();
757 filter_fn(res).then_some(TypoSuggestion::typo_from_res(*name, res))
761 Scope::BuiltinAttrs => {
762 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin(kw::Empty));
767 .map(|attr| TypoSuggestion::typo_from_res(attr.name, res)),
771 Scope::ExternPrelude => {
772 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
773 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
774 filter_fn(res).then_some(TypoSuggestion::typo_from_res(ident.name, res))
777 Scope::ToolPrelude => {
778 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
780 this.registered_tools
782 .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
785 Scope::StdLibPrelude => {
786 if let Some(prelude) = this.prelude {
787 let mut tmp_suggestions = Vec::new();
788 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
792 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
796 Scope::BuiltinTypes => {
797 suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| {
798 let res = Res::PrimTy(*prim_ty);
799 filter_fn(res).then_some(TypoSuggestion::typo_from_res(prim_ty.name(), res))
807 // Make sure error reporting is deterministic.
808 suggestions.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap());
810 match find_best_match_for_name(
811 &suggestions.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
815 Some(found) if found != ident.name => {
816 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
822 fn lookup_import_candidates_from_module<FilterFn>(
825 namespace: Namespace,
826 parent_scope: &ParentScope<'a>,
827 start_module: Module<'a>,
830 ) -> Vec<ImportSuggestion>
832 FilterFn: Fn(Res) -> bool,
834 let mut candidates = Vec::new();
835 let mut seen_modules = FxHashSet::default();
836 let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), true)];
837 let mut worklist_via_import = vec![];
839 while let Some((in_module, path_segments, accessible)) = match worklist.pop() {
840 None => worklist_via_import.pop(),
843 let in_module_is_extern = !in_module.def_id().is_local();
844 // We have to visit module children in deterministic order to avoid
845 // instabilities in reported imports (#43552).
846 in_module.for_each_child(self, |this, ident, ns, name_binding| {
847 // avoid non-importable candidates
848 if !name_binding.is_importable() {
852 let child_accessible =
853 accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
855 // do not venture inside inaccessible items of other crates
856 if in_module_is_extern && !child_accessible {
860 let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
862 // There is an assumption elsewhere that paths of variants are in the enum's
863 // declaration and not imported. With this assumption, the variant component is
864 // chopped and the rest of the path is assumed to be the enum's own path. For
865 // errors where a variant is used as the type instead of the enum, this causes
866 // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
867 if via_import && name_binding.is_possibly_imported_variant() {
871 // #90113: Do not count an inaccessible reexported item as a candidate.
872 if let NameBindingKind::Import { binding, .. } = name_binding.kind {
873 if this.is_accessible_from(binding.vis, parent_scope.module)
874 && !this.is_accessible_from(name_binding.vis, parent_scope.module)
880 // collect results based on the filter function
881 // avoid suggesting anything from the same module in which we are resolving
882 // avoid suggesting anything with a hygienic name
883 if ident.name == lookup_ident.name
885 && !ptr::eq(in_module, parent_scope.module)
886 && !ident.span.normalize_to_macros_2_0().from_expansion()
888 let res = name_binding.res();
891 let mut segms = path_segments.clone();
892 if lookup_ident.span.rust_2018() {
893 // crate-local absolute paths start with `crate::` in edition 2018
894 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
895 segms.insert(0, ast::PathSegment::from_ident(crate_name));
898 segms.push(ast::PathSegment::from_ident(ident));
899 let path = Path { span: name_binding.span, segments: segms, tokens: None };
900 let did = match res {
901 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
902 _ => res.opt_def_id(),
905 if child_accessible {
906 // Remove invisible match if exists
907 if let Some(idx) = candidates
909 .position(|v: &ImportSuggestion| v.did == did && !v.accessible)
911 candidates.remove(idx);
915 if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
916 // See if we're recommending TryFrom, TryInto, or FromIterator and add
917 // a note about editions
918 let note = if let Some(did) = did {
919 let requires_note = !did.is_local()
920 && this.cstore().item_attrs_untracked(did, this.session).any(
922 if attr.has_name(sym::rustc_diagnostic_item) {
923 [sym::TryInto, sym::TryFrom, sym::FromIterator]
925 .contains(&attr.value_str())
932 requires_note.then(|| {
934 "'{}' is included in the prelude starting in Edition 2021",
935 path_names_to_string(&path)
942 candidates.push(ImportSuggestion {
946 accessible: child_accessible,
953 // collect submodules to explore
954 if let Some(module) = name_binding.module() {
956 let mut path_segments = path_segments.clone();
957 path_segments.push(ast::PathSegment::from_ident(ident));
959 let is_extern_crate_that_also_appears_in_prelude =
960 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
962 if !is_extern_crate_that_also_appears_in_prelude {
963 // add the module to the lookup
964 if seen_modules.insert(module.def_id()) {
965 if via_import { &mut worklist_via_import } else { &mut worklist }
966 .push((module, path_segments, child_accessible));
973 // If only some candidates are accessible, take just them
974 if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
975 candidates = candidates.into_iter().filter(|x| x.accessible).collect();
981 /// When name resolution fails, this method can be used to look up candidate
982 /// entities with the expected name. It allows filtering them using the
983 /// supplied predicate (which should be used to only accept the types of
984 /// definitions expected, e.g., traits). The lookup spans across all crates.
986 /// N.B., the method does not look into imports, but this is not a problem,
987 /// since we report the definitions (thus, the de-aliased imports).
988 crate fn lookup_import_candidates<FilterFn>(
991 namespace: Namespace,
992 parent_scope: &ParentScope<'a>,
994 ) -> Vec<ImportSuggestion>
996 FilterFn: Fn(Res) -> bool,
998 let mut suggestions = self.lookup_import_candidates_from_module(
1003 Ident::with_dummy_span(kw::Crate),
1007 if lookup_ident.span.rust_2018() {
1008 let extern_prelude_names = self.extern_prelude.clone();
1009 for (ident, _) in extern_prelude_names.into_iter() {
1010 if ident.span.from_expansion() {
1011 // Idents are adjusted to the root context before being
1012 // resolved in the extern prelude, so reporting this to the
1013 // user is no help. This skips the injected
1014 // `extern crate std` in the 2018 edition, which would
1015 // otherwise cause duplicate suggestions.
1018 if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
1019 let crate_root = self.expect_module(crate_id.as_def_id());
1020 suggestions.extend(self.lookup_import_candidates_from_module(
1035 crate fn unresolved_macro_suggestions(
1037 err: &mut Diagnostic,
1038 macro_kind: MacroKind,
1039 parent_scope: &ParentScope<'a>,
1042 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
1043 let suggestion = self.early_lookup_typo_candidate(
1044 ScopeSet::Macro(macro_kind),
1049 self.add_typo_suggestion(err, suggestion, ident.span);
1051 let import_suggestions =
1052 self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected);
1058 &import_suggestions,
1063 if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
1064 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
1065 err.span_note(ident.span, &msg);
1068 if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
1069 err.help("have you added the `#[macro_use]` on the module/import?");
1072 for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
1073 if let Ok(binding) = self.early_resolve_ident_in_lexical_scope(
1075 ScopeSet::All(ns, false),
1080 let desc = match binding.res() {
1081 Res::Def(DefKind::Macro(MacroKind::Bang), _) => {
1082 "a function-like macro".to_string()
1084 Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => {
1085 format!("an attribute: `#[{}]`", ident)
1087 Res::Def(DefKind::Macro(MacroKind::Derive), _) => {
1088 format!("a derive macro: `#[derive({})]`", ident)
1091 // Don't confuse the user with tool modules.
1094 Res::Def(DefKind::Trait, _) if macro_kind == MacroKind::Derive => {
1095 "only a trait, without a derive macro".to_string()
1101 macro_kind.article(),
1102 macro_kind.descr_expected(),
1105 if let crate::NameBindingKind::Import { import, .. } = binding.kind {
1106 if !import.span.is_dummy() {
1109 &format!("`{}` is imported here, but it is {}", ident, desc),
1111 // Silence the 'unused import' warning we might get,
1112 // since this diagnostic already covers that import.
1113 self.record_use(ident, binding, false);
1117 err.note(&format!("`{}` is in scope, but it is {}", ident, desc));
1123 crate fn add_typo_suggestion(
1125 err: &mut Diagnostic,
1126 suggestion: Option<TypoSuggestion>,
1129 let suggestion = match suggestion {
1130 None => return false,
1131 // We shouldn't suggest underscore.
1132 Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
1133 Some(suggestion) => suggestion,
1135 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
1136 LOCAL_CRATE => self.opt_span(def_id),
1140 .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
1143 if let Some(def_span) = def_span {
1144 if span.overlaps(def_span) {
1145 // Don't suggest typo suggestion for itself like in the following:
1146 // error[E0423]: expected function, tuple struct or tuple variant, found struct `X`
1147 // --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14
1150 // | ----------- `X` defined here
1152 // LL | const Y: X = X("ö");
1153 // | -------------^^^^^^- similarly named constant `Y` defined here
1155 // help: use struct literal syntax instead
1157 // LL | const Y: X = X {};
1159 // help: a constant with a similar name exists
1161 // LL | const Y: X = Y("ö");
1165 let prefix = match suggestion.target {
1166 SuggestionTarget::SimilarlyNamed => "similarly named ",
1167 SuggestionTarget::SingleItem => "",
1171 self.session.source_map().guess_head_span(def_span),
1173 "{}{} `{}` defined here",
1175 suggestion.res.descr(),
1176 suggestion.candidate.as_str(),
1180 let msg = match suggestion.target {
1181 SuggestionTarget::SimilarlyNamed => format!(
1182 "{} {} with a similar name exists",
1183 suggestion.res.article(),
1184 suggestion.res.descr()
1186 SuggestionTarget::SingleItem => {
1187 format!("maybe you meant this {}", suggestion.res.descr())
1190 err.span_suggestion(
1193 suggestion.candidate.to_string(),
1194 Applicability::MaybeIncorrect,
1199 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
1201 if b.span.is_dummy() || self.session.source_map().span_to_snippet(b.span).is_err() {
1202 // These already contain the "built-in" prefix or look bad with it.
1204 !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);
1205 let (built_in, from) = if from_prelude {
1206 ("", " from prelude")
1207 } else if b.is_extern_crate()
1209 && self.session.opts.externs.get(ident.as_str()).is_some()
1211 ("", " passed with `--extern`")
1212 } else if add_built_in {
1218 let a = if built_in.is_empty() { res.article() } else { "a" };
1219 format!("{a}{built_in} {thing}{from}", thing = res.descr())
1221 let introduced = if b.is_import() { "imported" } else { "defined" };
1222 format!("the {thing} {introduced} here", thing = res.descr())
1226 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
1227 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
1228 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
1229 // We have to print the span-less alternative first, otherwise formatting looks bad.
1230 (b2, b1, misc2, misc1, true)
1232 (b1, b2, misc1, misc2, false)
1235 let mut err = struct_span_err!(self.session, ident.span, E0659, "`{ident}` is ambiguous");
1236 err.span_label(ident.span, "ambiguous name");
1237 err.note(&format!("ambiguous because of {}", kind.descr()));
1239 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
1240 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
1241 let note_msg = format!("`{ident}` could{also} refer to {what}");
1243 let thing = b.res().descr();
1244 let mut help_msgs = Vec::new();
1245 if b.is_glob_import()
1246 && (kind == AmbiguityKind::GlobVsGlob
1247 || kind == AmbiguityKind::GlobVsExpanded
1248 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
1250 help_msgs.push(format!(
1251 "consider adding an explicit import of `{ident}` to disambiguate"
1254 if b.is_extern_crate() && ident.span.rust_2018() {
1255 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
1257 if misc == AmbiguityErrorMisc::SuggestCrate {
1259 .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously"))
1260 } else if misc == AmbiguityErrorMisc::SuggestSelf {
1262 .push(format!("use `self::{ident}` to refer to this {thing} unambiguously"))
1265 err.span_note(b.span, ¬e_msg);
1266 for (i, help_msg) in help_msgs.iter().enumerate() {
1267 let or = if i == 0 { "" } else { "or " };
1268 err.help(&format!("{}{}", or, help_msg));
1272 could_refer_to(b1, misc1, "");
1273 could_refer_to(b2, misc2, " also");
1277 /// If the binding refers to a tuple struct constructor with fields,
1278 /// returns the span of its fields.
1279 fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option<Span> {
1280 if let NameBindingKind::Res(
1281 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
1285 let def_id = self.parent(ctor_def_id).expect("no parent for a constructor");
1286 let fields = self.field_names.get(&def_id)?;
1287 return fields.iter().map(|name| name.span).reduce(Span::to); // None for `struct Foo()`
1292 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
1293 let PrivacyError { ident, binding, .. } = *privacy_error;
1295 let res = binding.res();
1296 let ctor_fields_span = self.ctor_fields_span(binding);
1297 let plain_descr = res.descr().to_string();
1298 let nonimport_descr =
1299 if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
1300 let import_descr = nonimport_descr.clone() + " import";
1302 |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
1304 // Print the primary message.
1305 let descr = get_descr(binding);
1307 struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident);
1308 err.span_label(ident.span, &format!("private {}", descr));
1309 if let Some(span) = ctor_fields_span {
1310 err.span_label(span, "a constructor is private if any of the fields is private");
1313 // Print the whole import chain to make it easier to see what happens.
1314 let first_binding = binding;
1315 let mut next_binding = Some(binding);
1316 let mut next_ident = ident;
1317 while let Some(binding) = next_binding {
1318 let name = next_ident;
1319 next_binding = match binding.kind {
1320 _ if res == Res::Err => None,
1321 NameBindingKind::Import { binding, import, .. } => match import.kind {
1322 _ if binding.span.is_dummy() => None,
1323 ImportKind::Single { source, .. } => {
1324 next_ident = source;
1327 ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding),
1328 ImportKind::ExternCrate { .. } => None,
1333 let first = ptr::eq(binding, first_binding);
1335 "{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
1336 and_refers_to = if first { "" } else { "...and refers to " },
1337 item = get_descr(binding),
1338 which = if first { "" } else { " which" },
1339 dots = if next_binding.is_some() { "..." } else { "" },
1341 let def_span = self.session.source_map().guess_head_span(binding.span);
1342 let mut note_span = MultiSpan::from_span(def_span);
1343 if !first && binding.vis.is_public() {
1344 note_span.push_span_label(def_span, "consider importing it directly");
1346 err.span_note(note_span, &msg);
1352 crate fn find_similarly_named_module_or_crate(
1355 current_module: &Module<'a>,
1356 ) -> Option<Symbol> {
1357 let mut candidates = self
1360 .map(|(ident, _)| ident.name)
1364 .filter(|(_, module)| {
1365 current_module.is_ancestor_of(module) && !ptr::eq(current_module, *module)
1367 .flat_map(|(_, module)| module.kind.name()),
1369 .filter(|c| !c.to_string().is_empty())
1370 .collect::<Vec<_>>();
1373 match find_best_match_for_name(&candidates, ident, None) {
1374 Some(sugg) if sugg == ident => None,
1380 impl<'a, 'b> ImportResolver<'a, 'b> {
1381 /// Adds suggestions for a path that cannot be resolved.
1382 pub(crate) fn make_path_suggestion(
1385 mut path: Vec<Segment>,
1386 parent_scope: &ParentScope<'b>,
1387 ) -> Option<(Vec<Segment>, Vec<String>)> {
1388 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
1390 match (path.get(0), path.get(1)) {
1391 // `{{root}}::ident::...` on both editions.
1392 // On 2015 `{{root}}` is usually added implicitly.
1393 (Some(fst), Some(snd))
1394 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
1395 // `ident::...` on 2018.
1397 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
1399 // Insert a placeholder that's later replaced by `self`/`super`/etc.
1400 path.insert(0, Segment::from_ident(Ident::empty()));
1405 self.make_missing_self_suggestion(path.clone(), parent_scope)
1406 .or_else(|| self.make_missing_crate_suggestion(path.clone(), parent_scope))
1407 .or_else(|| self.make_missing_super_suggestion(path.clone(), parent_scope))
1408 .or_else(|| self.make_external_crate_suggestion(path, parent_scope))
1411 /// Suggest a missing `self::` if that resolves to an correct module.
1415 /// LL | use foo::Bar;
1416 /// | ^^^ did you mean `self::foo`?
1418 fn make_missing_self_suggestion(
1420 mut path: Vec<Segment>,
1421 parent_scope: &ParentScope<'b>,
1422 ) -> Option<(Vec<Segment>, Vec<String>)> {
1423 // Replace first ident with `self` and check if that is valid.
1424 path[0].ident.name = kw::SelfLower;
1425 let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1426 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1427 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1430 /// Suggests a missing `crate::` if that resolves to an correct module.
1434 /// LL | use foo::Bar;
1435 /// | ^^^ did you mean `crate::foo`?
1437 fn make_missing_crate_suggestion(
1439 mut path: Vec<Segment>,
1440 parent_scope: &ParentScope<'b>,
1441 ) -> Option<(Vec<Segment>, Vec<String>)> {
1442 // Replace first ident with `crate` and check if that is valid.
1443 path[0].ident.name = kw::Crate;
1444 let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1445 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1446 if let PathResult::Module(..) = result {
1450 "`use` statements changed in Rust 2018; read more at \
1451 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1461 /// Suggests a missing `super::` if that resolves to an correct module.
1465 /// LL | use foo::Bar;
1466 /// | ^^^ did you mean `super::foo`?
1468 fn make_missing_super_suggestion(
1470 mut path: Vec<Segment>,
1471 parent_scope: &ParentScope<'b>,
1472 ) -> Option<(Vec<Segment>, Vec<String>)> {
1473 // Replace first ident with `crate` and check if that is valid.
1474 path[0].ident.name = kw::Super;
1475 let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1476 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1477 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1480 /// Suggests a missing external crate name if that resolves to an correct module.
1484 /// LL | use foobar::Baz;
1485 /// | ^^^^^^ did you mean `baz::foobar`?
1488 /// Used when importing a submodule of an external crate but missing that crate's
1489 /// name as the first part of path.
1490 fn make_external_crate_suggestion(
1492 mut path: Vec<Segment>,
1493 parent_scope: &ParentScope<'b>,
1494 ) -> Option<(Vec<Segment>, Vec<String>)> {
1495 if path[1].ident.span.rust_2015() {
1499 // Sort extern crate names in *reverse* order to get
1500 // 1) some consistent ordering for emitted diagnostics, and
1501 // 2) `std` suggestions before `core` suggestions.
1502 let mut extern_crate_names =
1503 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1504 extern_crate_names.sort_by(|a, b| b.as_str().partial_cmp(a.as_str()).unwrap());
1506 for name in extern_crate_names.into_iter() {
1507 // Replace first ident with a crate name and check if that is valid.
1508 path[0].ident.name = name;
1509 let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1511 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1514 if let PathResult::Module(..) = result {
1515 return Some((path, Vec::new()));
1522 /// Suggests importing a macro from the root of the crate rather than a module within
1526 /// help: a macro with this name exists at the root of the crate
1528 /// LL | use issue_59764::makro;
1529 /// | ^^^^^^^^^^^^^^^^^^
1531 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1532 /// at the root of the crate instead of the module where it is defined
1534 pub(crate) fn check_for_module_export_macro(
1536 import: &'b Import<'b>,
1537 module: ModuleOrUniformRoot<'b>,
1539 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1540 let ModuleOrUniformRoot::Module(mut crate_module) = module else {
1544 while let Some(parent) = crate_module.parent {
1545 crate_module = parent;
1548 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1549 // Don't make a suggestion if the import was already from the root of the
1554 let resolutions = self.r.resolutions(crate_module).borrow();
1555 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1556 let binding = resolution.borrow().binding()?;
1557 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1558 let module_name = crate_module.kind.name().unwrap();
1559 let import_snippet = match import.kind {
1560 ImportKind::Single { source, target, .. } if source != target => {
1561 format!("{} as {}", source, target)
1563 _ => format!("{}", ident),
1566 let mut corrections: Vec<(Span, String)> = Vec::new();
1567 if !import.is_nested() {
1568 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1569 // intermediate segments.
1570 corrections.push((import.span, format!("{}::{}", module_name, import_snippet)));
1572 // Find the binding span (and any trailing commas and spaces).
1573 // ie. `use a::b::{c, d, e};`
1575 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1581 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1582 found_closing_brace, binding_span
1585 let mut removal_span = binding_span;
1586 if found_closing_brace {
1587 // If the binding span ended with a closing brace, as in the below example:
1588 // ie. `use a::b::{c, d};`
1590 // Then expand the span of characters to remove to include the previous
1591 // binding's trailing comma.
1592 // ie. `use a::b::{c, d};`
1594 if let Some(previous_span) =
1595 extend_span_to_previous_binding(self.r.session, binding_span)
1597 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1598 removal_span = removal_span.with_lo(previous_span.lo());
1601 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1603 // Remove the `removal_span`.
1604 corrections.push((removal_span, "".to_string()));
1606 // Find the span after the crate name and if it has nested imports immediately
1607 // after the crate name already.
1608 // ie. `use a::b::{c, d};`
1610 // or `use a::{b, c, d}};`
1612 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1618 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1619 has_nested, after_crate_name
1622 let source_map = self.r.session.source_map();
1624 // Add the import to the start, with a `{` if required.
1625 let start_point = source_map.start_point(after_crate_name);
1626 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1630 // In this case, `start_snippet` must equal '{'.
1631 format!("{}{}, ", start_snippet, import_snippet)
1633 // In this case, add a `{`, then the moved import, then whatever
1634 // was there before.
1635 format!("{{{}, {}", import_snippet, start_snippet)
1640 // Add a `};` to the end if nested, matching the `{` added at the start.
1642 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1646 let suggestion = Some((
1648 String::from("a macro with this name exists at the root of the crate"),
1649 Applicability::MaybeIncorrect,
1652 "this could be because a macro annotated with `#[macro_export]` will be exported \
1653 at the root of the crate instead of the module where it is defined"
1656 Some((suggestion, note))
1663 /// Given a `binding_span` of a binding within a use statement:
1666 /// use foo::{a, b, c};
1670 /// then return the span until the next binding or the end of the statement:
1673 /// use foo::{a, b, c};
1676 pub(crate) fn find_span_of_binding_until_next_binding(
1681 let source_map = sess.source_map();
1683 // Find the span of everything after the binding.
1684 // ie. `a, e};` or `a};`
1685 let binding_until_end = binding_span.with_hi(use_span.hi());
1687 // Find everything after the binding but not including the binding.
1688 // ie. `, e};` or `};`
1689 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1691 // Keep characters in the span until we encounter something that isn't a comma or
1695 // Also note whether a closing brace character was encountered. If there
1696 // was, then later go backwards to remove any trailing commas that are left.
1697 let mut found_closing_brace = false;
1698 let after_binding_until_next_binding =
1699 source_map.span_take_while(after_binding_until_end, |&ch| {
1701 found_closing_brace = true;
1703 ch == ' ' || ch == ','
1706 // Combine the two spans.
1707 // ie. `a, ` or `a`.
1709 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1710 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1712 (found_closing_brace, span)
1715 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1719 /// use foo::a::{a, b, c};
1720 /// ^^--- binding span
1724 /// use foo::{a, b, c};
1725 /// --- binding span
1727 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1728 let source_map = sess.source_map();
1730 // `prev_source` will contain all of the source that came before the span.
1731 // Then split based on a command and take the first (ie. closest to our span)
1732 // snippet. In the example, this is a space.
1733 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1735 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1736 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1737 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1741 let prev_comma = prev_comma.first().unwrap();
1742 let prev_starting_brace = prev_starting_brace.first().unwrap();
1744 // If the amount of source code before the comma is greater than
1745 // the amount of source code before the starting brace then we've only
1746 // got one item in the nested item (eg. `issue_52891::{self}`).
1747 if prev_comma.len() > prev_starting_brace.len() {
1751 Some(binding_span.with_lo(BytePos(
1752 // Take away the number of bytes for the characters we've found and an
1753 // extra for the comma.
1754 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1758 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1759 /// it is a nested use tree.
1762 /// use foo::a::{b, c};
1763 /// ^^^^^^^^^^ // false
1765 /// use foo::{a, b, c};
1766 /// ^^^^^^^^^^ // true
1768 /// use foo::{a, b::{c, d}};
1769 /// ^^^^^^^^^^^^^^^ // true
1771 fn find_span_immediately_after_crate_name(
1773 module_name: Symbol,
1777 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1778 module_name, use_span
1780 let source_map = sess.source_map();
1782 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1783 let mut num_colons = 0;
1784 // Find second colon.. `use issue_59764:`
1785 let until_second_colon = source_map.span_take_while(use_span, |c| {
1789 !matches!(c, ':' if num_colons == 2)
1791 // Find everything after the second colon.. `foo::{baz, makro};`
1792 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1794 let mut found_a_non_whitespace_character = false;
1795 // Find the first non-whitespace character in `from_second_colon`.. `f`
1796 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1797 if found_a_non_whitespace_character {
1800 if !c.is_whitespace() {
1801 found_a_non_whitespace_character = true;
1806 // Find the first `{` in from_second_colon.. `foo::{`
1807 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1809 (next_left_bracket == after_second_colon, from_second_colon)
1812 /// When an entity with a given name is not available in scope, we search for
1813 /// entities with that name in all crates. This method allows outputting the
1814 /// results of this search in a programmer-friendly way
1815 crate fn show_candidates(
1816 definitions: &rustc_hir::definitions::Definitions,
1818 err: &mut Diagnostic,
1819 // This is `None` if all placement locations are inside expansions
1820 use_placement_span: Option<Span>,
1821 candidates: &[ImportSuggestion],
1825 if candidates.is_empty() {
1829 let mut accessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> =
1831 let mut inaccessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> =
1834 candidates.iter().for_each(|c| {
1835 (if c.accessible { &mut accessible_path_strings } else { &mut inaccessible_path_strings })
1836 .push((path_names_to_string(&c.path), c.descr, c.did, &c.note))
1839 // we want consistent results across executions, but candidates are produced
1840 // by iterating through a hash map, so make sure they are ordered:
1841 for path_strings in [&mut accessible_path_strings, &mut inaccessible_path_strings] {
1842 path_strings.sort_by(|a, b| a.0.cmp(&b.0));
1843 let core_path_strings =
1844 path_strings.drain_filter(|p| p.0.starts_with("core::")).collect::<Vec<_>>();
1845 path_strings.extend(core_path_strings);
1846 path_strings.dedup_by(|a, b| a.0 == b.0);
1849 if !accessible_path_strings.is_empty() {
1850 let (determiner, kind) = if accessible_path_strings.len() == 1 {
1851 ("this", accessible_path_strings[0].1)
1853 ("one of these", "items")
1856 let instead = if instead { " instead" } else { "" };
1857 let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
1859 for note in accessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
1863 if let Some(span) = use_placement_span {
1864 for candidate in &mut accessible_path_strings {
1865 // produce an additional newline to separate the new use statement
1866 // from the directly following item.
1867 let additional_newline = if found_use { "" } else { "\n" };
1868 candidate.0 = format!("use {};\n{}", &candidate.0, additional_newline);
1871 err.span_suggestions(
1874 accessible_path_strings.into_iter().map(|a| a.0),
1875 Applicability::Unspecified,
1880 for candidate in accessible_path_strings {
1882 msg.push_str(&candidate.0);
1888 assert!(!inaccessible_path_strings.is_empty());
1890 if inaccessible_path_strings.len() == 1 {
1891 let (name, descr, def_id, note) = &inaccessible_path_strings[0];
1892 let msg = format!("{} `{}` exists but is inaccessible", descr, name);
1894 if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
1895 let span = definitions.def_span(local_def_id);
1896 let span = session.source_map().guess_head_span(span);
1897 let mut multi_span = MultiSpan::from_span(span);
1898 multi_span.push_span_label(span, "not accessible".to_string());
1899 err.span_note(multi_span, &msg);
1903 if let Some(note) = (*note).as_deref() {
1907 let (_, descr_first, _, _) = &inaccessible_path_strings[0];
1908 let descr = if inaccessible_path_strings
1911 .all(|(_, descr, _, _)| descr == descr_first)
1913 descr_first.to_string()
1918 let mut msg = format!("these {}s exist but are inaccessible", descr);
1919 let mut has_colon = false;
1921 let mut spans = Vec::new();
1922 for (name, _, def_id, _) in &inaccessible_path_strings {
1923 if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
1924 let span = definitions.def_span(local_def_id);
1925 let span = session.source_map().guess_head_span(span);
1926 spans.push((name, span));
1937 let mut multi_span = MultiSpan::from_spans(spans.iter().map(|(_, sp)| *sp).collect());
1938 for (name, span) in spans {
1939 multi_span.push_span_label(span, format!("`{}`: not accessible", name));
1942 for note in inaccessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
1946 err.span_note(multi_span, &msg);