4 use rustc_ast::{self as ast, Path};
5 use rustc_ast_pretty::pprust;
6 use rustc_data_structures::fx::FxHashSet;
7 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
8 use rustc_feature::BUILTIN_ATTRIBUTES;
9 use rustc_hir::def::Namespace::{self, *};
10 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
11 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
12 use rustc_hir::PrimTy;
13 use rustc_middle::bug;
14 use rustc_middle::ty::{self, DefIdTree};
15 use rustc_session::Session;
16 use rustc_span::hygiene::MacroKind;
17 use rustc_span::lev_distance::find_best_match_for_name;
18 use rustc_span::source_map::SourceMap;
19 use rustc_span::symbol::{kw, sym, Ident, Symbol};
20 use rustc_span::{BytePos, MultiSpan, Span};
23 use crate::imports::{Import, ImportKind, ImportResolver};
24 use crate::path_names_to_string;
25 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
27 BindingError, CrateLint, HasGenericParams, MacroRulesScope, Module, ModuleOrUniformRoot,
29 use crate::{NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
30 use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment};
32 type Res = def::Res<ast::NodeId>;
34 /// A vector of spans and replacements, a message and applicability.
35 crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
37 /// Potential candidate for an undeclared or out-of-scope label - contains the ident of a
38 /// similarly named label and whether or not it is reachable.
39 crate type LabelSuggestion = (Ident, bool);
41 crate struct TypoSuggestion {
42 pub candidate: Symbol,
47 crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
48 TypoSuggestion { candidate, res }
52 /// A free importable items suggested in case of resolution failure.
53 crate struct ImportSuggestion {
54 pub did: Option<DefId>,
55 pub descr: &'static str,
60 /// Adjust the impl span so that just the `impl` keyword is taken by removing
61 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
62 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
64 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
65 /// parser. If you need to use this function or something similar, please consider updating the
66 /// `source_map` functions and this function to something more robust.
67 fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
68 let impl_span = sm.span_until_char(impl_span, '<');
69 sm.span_until_whitespace(impl_span)
72 impl<'a> Resolver<'a> {
73 crate fn add_module_candidates(
76 names: &mut Vec<TypoSuggestion>,
77 filter_fn: &impl Fn(Res) -> bool,
79 for (key, resolution) in self.resolutions(module).borrow().iter() {
80 if let Some(binding) = resolution.borrow().binding {
81 let res = binding.res();
83 names.push(TypoSuggestion::from_res(key.ident.name, res));
89 /// Combines an error with provided span and emits it.
91 /// This takes the error provided, combines it with the span and any additional spans inside the
92 /// error and emits it.
93 crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
94 self.into_struct_error(span, resolution_error).emit();
97 crate fn into_struct_error(
100 resolution_error: ResolutionError<'_>,
101 ) -> DiagnosticBuilder<'_> {
102 match resolution_error {
103 ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
104 let mut err = struct_span_err!(
108 "can't use generic parameters from outer function",
110 err.span_label(span, "use of generic parameter from outer function".to_string());
112 let sm = self.session.source_map();
114 Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => {
115 if let Some(impl_span) =
116 maybe_impl_defid.and_then(|(def_id, _)| self.opt_span(def_id))
119 reduce_impl_span_to_impl_keyword(sm, impl_span),
120 "`Self` type implicitly declared here, by this `impl`",
123 match (maybe_trait_defid, maybe_impl_defid) {
125 err.span_label(span, "can't use `Self` here");
128 err.span_label(span, "use a type here instead");
130 (None, None) => bug!("`impl` without trait nor type?"),
134 Res::Def(DefKind::TyParam, def_id) => {
135 if let Some(span) = self.opt_span(def_id) {
136 err.span_label(span, "type parameter from outer function");
139 Res::Def(DefKind::ConstParam, def_id) => {
140 if let Some(span) = self.opt_span(def_id) {
141 err.span_label(span, "const parameter from outer function");
146 "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
147 DefKind::TyParam or DefKind::ConstParam"
152 if has_generic_params == HasGenericParams::Yes {
153 // Try to retrieve the span of the function signature and generate a new
154 // message with a local type or const parameter.
155 let sugg_msg = "try using a local generic parameter instead";
156 if let Some((sugg_span, snippet)) = sm.generate_local_type_param_snippet(span) {
157 // Suggest the modification to the user
162 Applicability::MachineApplicable,
164 } else if let Some(sp) = sm.generate_fn_name_span(span) {
167 "try adding a local generic parameter in this method instead"
171 err.help("try using a local generic parameter instead");
177 ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
178 let mut err = struct_span_err!(
182 "the name `{}` is already used for a generic \
183 parameter in this item's generic parameters",
186 err.span_label(span, "already used");
187 err.span_label(first_use_span, format!("first use of `{}`", name));
190 ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
191 let mut err = struct_span_err!(
195 "method `{}` is not a member of trait `{}`",
199 err.span_label(span, format!("not a member of trait `{}`", trait_));
202 ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
203 let mut err = struct_span_err!(
207 "type `{}` is not a member of trait `{}`",
211 err.span_label(span, format!("not a member of trait `{}`", trait_));
214 ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
215 let mut err = struct_span_err!(
219 "const `{}` is not a member of trait `{}`",
223 err.span_label(span, format!("not a member of trait `{}`", trait_));
226 ResolutionError::VariableNotBoundInPattern(binding_error) => {
227 let BindingError { name, target, origin, could_be_path } = binding_error;
229 let target_sp = target.iter().copied().collect::<Vec<_>>();
230 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
232 let msp = MultiSpan::from_spans(target_sp.clone());
233 let mut err = struct_span_err!(
237 "variable `{}` is not bound in all patterns",
240 for sp in target_sp {
241 err.span_label(sp, format!("pattern doesn't bind `{}`", name));
243 for sp in origin_sp {
244 err.span_label(sp, "variable not in all patterns");
247 let help_msg = format!(
248 "if you meant to match on a variant or a `const` item, consider \
249 making the path in the pattern qualified: `?::{}`",
252 err.span_help(span, &help_msg);
256 ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
257 let mut err = struct_span_err!(
261 "variable `{}` is bound inconsistently across alternatives separated by `|`",
264 err.span_label(span, "bound in different ways");
265 err.span_label(first_binding_span, "first binding");
268 ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
269 let mut err = struct_span_err!(
273 "identifier `{}` is bound more than once in this parameter list",
276 err.span_label(span, "used as parameter more than once");
279 ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
280 let mut err = struct_span_err!(
284 "identifier `{}` is bound more than once in the same pattern",
287 err.span_label(span, "used in a pattern more than once");
290 ResolutionError::UndeclaredLabel { name, suggestion } => {
291 let mut err = struct_span_err!(
295 "use of undeclared label `{}`",
299 err.span_label(span, format!("undeclared label `{}`", name));
302 // A reachable label with a similar name exists.
303 Some((ident, true)) => {
304 err.span_label(ident.span, "a label with a similar name is reachable");
307 "try using similarly named label",
308 ident.name.to_string(),
309 Applicability::MaybeIncorrect,
312 // An unreachable label with a similar name exists.
313 Some((ident, false)) => {
316 "a label with a similar name exists but is unreachable",
319 // No similarly-named labels exist.
325 ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
326 let mut err = struct_span_err!(
331 "`self` imports are only allowed within a { } list"
334 // None of the suggestions below would help with a case like `use self`.
336 // use foo::bar::self -> foo::bar
337 // use foo::bar::self as abc -> foo::bar as abc
340 "consider importing the module directly",
342 Applicability::MachineApplicable,
345 // use foo::bar::self -> foo::bar::{self}
346 // use foo::bar::self as abc -> foo::bar::{self as abc}
348 (span_with_rename.shrink_to_lo(), "{".to_string()),
349 (span_with_rename.shrink_to_hi(), "}".to_string()),
351 err.multipart_suggestion(
352 "alternatively, use the multi-path `use` syntax to import `self`",
354 Applicability::MachineApplicable,
359 ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
360 let mut err = struct_span_err!(
364 "`self` import can only appear once in an import list"
366 err.span_label(span, "can only appear once in an import list");
369 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
370 let mut err = struct_span_err!(
374 "`self` import can only appear in an import list with \
377 err.span_label(span, "can only appear in an import list with a non-empty prefix");
380 ResolutionError::FailedToResolve { label, suggestion } => {
382 struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
383 err.span_label(span, label);
385 if let Some((suggestions, msg, applicability)) = suggestion {
386 err.multipart_suggestion(&msg, suggestions, applicability);
391 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
392 let mut err = struct_span_err!(
397 "can't capture dynamic environment in a fn item"
399 err.help("use the `|| { ... }` closure form instead");
402 ResolutionError::AttemptToUseNonConstantValueInConstant(ident, sugg, current) => {
403 let mut err = struct_span_err!(
407 "attempt to use a non-constant value in a constant"
410 // ^^^ given this Span
411 // ------- get this Span to have an applicable suggestion
413 self.session.source_map().span_extend_to_prev_str(ident.span, current, true);
415 err.span_label(ident.span, &format!("this would need to be a `{}`", sugg));
417 let sp = sp.with_lo(BytePos(sp.lo().0 - current.len() as u32));
420 &format!("consider using `{}` instead of `{}`", sugg, current),
421 format!("{} {}", sugg, ident),
422 Applicability::MaybeIncorrect,
424 err.span_label(span, "non-constant value");
428 ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
429 let res = binding.res();
430 let shadows_what = res.descr();
431 let mut err = struct_span_err!(
435 "{}s cannot shadow {}s",
441 format!("cannot be named the same as {} {}", res.article(), shadows_what),
443 let participle = if binding.is_import() { "imported" } else { "defined" };
444 let msg = format!("the {} `{}` is {} here", shadows_what, name, participle);
445 err.span_label(binding.span, msg);
448 ResolutionError::ForwardDeclaredTyParam => {
449 let mut err = struct_span_err!(
453 "generic parameters with a default cannot use \
454 forward declared identifiers"
458 "defaulted generic parameters cannot be forward declared".to_string(),
462 ResolutionError::ParamInTyOfConstParam(name) => {
463 let mut err = struct_span_err!(
467 "the type of const parameters must not depend on other generic parameters"
471 format!("the type must not depend on the parameter `{}`", name),
475 ResolutionError::ParamInAnonConstInTyDefault(name) => {
476 let mut err = self.session.struct_span_err(
478 "constant values inside of type parameter defaults must not depend on generic parameters",
482 format!("the anonymous constant must not depend on the parameter `{}`", name),
486 ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
487 let mut err = self.session.struct_span_err(
489 "generic parameters may not be used in const operations",
491 err.span_label(span, &format!("cannot perform const operation using `{}`", name));
494 err.note("type parameters may not be used in const expressions");
497 "const parameters may only be used as standalone arguments, i.e. `{}`",
501 err.help("use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions");
505 ResolutionError::SelfInTyParamDefault => {
506 let mut err = struct_span_err!(
510 "type parameters cannot use `Self` in their defaults"
512 err.span_label(span, "`Self` in type parameter default".to_string());
515 ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
516 let mut err = struct_span_err!(
520 "use of unreachable label `{}`",
524 err.span_label(definition_span, "unreachable label defined here");
525 err.span_label(span, format!("unreachable label `{}`", name));
527 "labels are unreachable through functions, closures, async blocks and modules",
531 // A reachable label with a similar name exists.
532 Some((ident, true)) => {
533 err.span_label(ident.span, "a label with a similar name is reachable");
536 "try using similarly named label",
537 ident.name.to_string(),
538 Applicability::MaybeIncorrect,
541 // An unreachable label with a similar name exists.
542 Some((ident, false)) => {
545 "a label with a similar name exists but is also unreachable",
548 // No similarly-named labels exist.
557 crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
558 match vis_resolution_error {
559 VisResolutionError::Relative2018(span, path) => {
560 let mut err = self.session.struct_span_err(
562 "relative paths are not supported in visibilities on 2018 edition",
567 format!("crate::{}", pprust::path_to_string(&path)),
568 Applicability::MaybeIncorrect,
572 VisResolutionError::AncestorOnly(span) => struct_span_err!(
576 "visibilities can only be restricted to ancestor modules"
578 VisResolutionError::FailedToResolve(span, label, suggestion) => {
579 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
581 VisResolutionError::ExpectedFound(span, path_str, res) => {
582 let mut err = struct_span_err!(
586 "expected module, found {} `{}`",
590 err.span_label(span, "not a module");
593 VisResolutionError::Indeterminate(span) => struct_span_err!(
597 "cannot determine resolution for the visibility"
599 VisResolutionError::ModuleOnly(span) => {
600 self.session.struct_span_err(span, "visibility must resolve to a module")
606 /// Lookup typo candidate in scope for a macro or import.
607 fn early_lookup_typo_candidate(
609 scope_set: ScopeSet<'a>,
610 parent_scope: &ParentScope<'a>,
612 filter_fn: &impl Fn(Res) -> bool,
613 ) -> Option<TypoSuggestion> {
614 let mut suggestions = Vec::new();
615 let ctxt = ident.span.ctxt();
616 self.visit_scopes(scope_set, parent_scope, ctxt, |this, scope, use_prelude, _| {
618 Scope::DeriveHelpers(expn_id) => {
619 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
626 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
630 Scope::DeriveHelpersCompat => {
631 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
633 for derive in parent_scope.derives {
634 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
635 if let Ok((Some(ext), _)) = this.resolve_macro_path(
637 Some(MacroKind::Derive),
645 .map(|name| TypoSuggestion::from_res(*name, res)),
651 Scope::MacroRules(macro_rules_scope) => {
652 if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
653 let res = macro_rules_binding.binding.res();
656 .push(TypoSuggestion::from_res(macro_rules_binding.ident.name, res))
660 Scope::CrateRoot => {
661 let root_ident = Ident::new(kw::PathRoot, ident.span);
662 let root_module = this.resolve_crate_root(root_ident);
663 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
665 Scope::Module(module, _) => {
666 this.add_module_candidates(module, &mut suggestions, filter_fn);
668 Scope::RegisteredAttrs => {
669 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
672 this.registered_attrs
674 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
678 Scope::MacroUsePrelude => {
679 suggestions.extend(this.macro_use_prelude.iter().filter_map(
681 let res = binding.res();
682 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
686 Scope::BuiltinAttrs => {
687 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin(kw::Empty));
692 .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
696 Scope::ExternPrelude => {
697 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
698 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
699 filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
702 Scope::ToolPrelude => {
703 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
705 this.registered_tools
707 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
710 Scope::StdLibPrelude => {
711 if let Some(prelude) = this.prelude {
712 let mut tmp_suggestions = Vec::new();
713 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
717 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
721 Scope::BuiltinTypes => {
722 suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| {
723 let res = Res::PrimTy(*prim_ty);
724 filter_fn(res).then_some(TypoSuggestion::from_res(prim_ty.name(), res))
732 // Make sure error reporting is deterministic.
733 suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
735 match find_best_match_for_name(
736 &suggestions.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
740 Some(found) if found != ident.name => {
741 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
747 fn lookup_import_candidates_from_module<FilterFn>(
750 namespace: Namespace,
751 parent_scope: &ParentScope<'a>,
752 start_module: Module<'a>,
755 ) -> Vec<ImportSuggestion>
757 FilterFn: Fn(Res) -> bool,
759 let mut candidates = Vec::new();
760 let mut seen_modules = FxHashSet::default();
761 let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), true)];
762 let mut worklist_via_import = vec![];
764 while let Some((in_module, path_segments, accessible)) = match worklist.pop() {
765 None => worklist_via_import.pop(),
768 let in_module_is_extern = !in_module.def_id().unwrap().is_local();
769 // We have to visit module children in deterministic order to avoid
770 // instabilities in reported imports (#43552).
771 in_module.for_each_child(self, |this, ident, ns, name_binding| {
772 // avoid non-importable candidates
773 if !name_binding.is_importable() {
777 let child_accessible =
778 accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
780 // do not venture inside inaccessible items of other crates
781 if in_module_is_extern && !child_accessible {
785 let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
787 // There is an assumption elsewhere that paths of variants are in the enum's
788 // declaration and not imported. With this assumption, the variant component is
789 // chopped and the rest of the path is assumed to be the enum's own path. For
790 // errors where a variant is used as the type instead of the enum, this causes
791 // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
792 if via_import && name_binding.is_possibly_imported_variant() {
796 // collect results based on the filter function
797 // avoid suggesting anything from the same module in which we are resolving
798 if ident.name == lookup_ident.name
800 && !ptr::eq(in_module, parent_scope.module)
802 let res = name_binding.res();
805 let mut segms = path_segments.clone();
806 if lookup_ident.span.rust_2018() {
807 // crate-local absolute paths start with `crate::` in edition 2018
808 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
809 segms.insert(0, ast::PathSegment::from_ident(crate_name));
812 segms.push(ast::PathSegment::from_ident(ident));
813 let path = Path { span: name_binding.span, segments: segms, tokens: None };
814 let did = match res {
815 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
816 _ => res.opt_def_id(),
819 if child_accessible {
820 // Remove invisible match if exists
821 if let Some(idx) = candidates
823 .position(|v: &ImportSuggestion| v.did == did && !v.accessible)
825 candidates.remove(idx);
829 if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
830 candidates.push(ImportSuggestion {
834 accessible: child_accessible,
840 // collect submodules to explore
841 if let Some(module) = name_binding.module() {
843 let mut path_segments = path_segments.clone();
844 path_segments.push(ast::PathSegment::from_ident(ident));
846 let is_extern_crate_that_also_appears_in_prelude =
847 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
849 if !is_extern_crate_that_also_appears_in_prelude {
850 // add the module to the lookup
851 if seen_modules.insert(module.def_id().unwrap()) {
852 if via_import { &mut worklist_via_import } else { &mut worklist }
853 .push((module, path_segments, child_accessible));
860 // If only some candidates are accessible, take just them
861 if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
862 candidates = candidates.into_iter().filter(|x| x.accessible).collect();
868 /// When name resolution fails, this method can be used to look up candidate
869 /// entities with the expected name. It allows filtering them using the
870 /// supplied predicate (which should be used to only accept the types of
871 /// definitions expected, e.g., traits). The lookup spans across all crates.
873 /// N.B., the method does not look into imports, but this is not a problem,
874 /// since we report the definitions (thus, the de-aliased imports).
875 crate fn lookup_import_candidates<FilterFn>(
878 namespace: Namespace,
879 parent_scope: &ParentScope<'a>,
881 ) -> Vec<ImportSuggestion>
883 FilterFn: Fn(Res) -> bool,
885 let mut suggestions = self.lookup_import_candidates_from_module(
890 Ident::with_dummy_span(kw::Crate),
894 if lookup_ident.span.rust_2018() {
895 let extern_prelude_names = self.extern_prelude.clone();
896 for (ident, _) in extern_prelude_names.into_iter() {
897 if ident.span.from_expansion() {
898 // Idents are adjusted to the root context before being
899 // resolved in the extern prelude, so reporting this to the
900 // user is no help. This skips the injected
901 // `extern crate std` in the 2018 edition, which would
902 // otherwise cause duplicate suggestions.
905 if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
907 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
908 suggestions.extend(self.lookup_import_candidates_from_module(
923 crate fn unresolved_macro_suggestions(
925 err: &mut DiagnosticBuilder<'a>,
926 macro_kind: MacroKind,
927 parent_scope: &ParentScope<'a>,
930 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
931 let suggestion = self.early_lookup_typo_candidate(
932 ScopeSet::Macro(macro_kind),
937 self.add_typo_suggestion(err, suggestion, ident.span);
939 let import_suggestions =
940 self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, |res| {
941 matches!(res, Res::Def(DefKind::Macro(MacroKind::Bang), _))
943 show_candidates(err, None, &import_suggestions, false, true);
945 if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
946 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
947 err.span_note(ident.span, &msg);
949 if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
950 err.help("have you added the `#[macro_use]` on the module/import?");
954 crate fn add_typo_suggestion(
956 err: &mut DiagnosticBuilder<'_>,
957 suggestion: Option<TypoSuggestion>,
960 let suggestion = match suggestion {
961 None => return false,
962 // We shouldn't suggest underscore.
963 Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
964 Some(suggestion) => suggestion,
966 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
967 LOCAL_CRATE => self.opt_span(def_id),
971 .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
974 if let Some(def_span) = def_span {
975 if span.overlaps(def_span) {
976 // Don't suggest typo suggestion for itself like in the following:
977 // error[E0423]: expected function, tuple struct or tuple variant, found struct `X`
978 // --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14
981 // | ----------- `X` defined here
983 // LL | const Y: X = X("ö");
984 // | -------------^^^^^^- similarly named constant `Y` defined here
986 // help: use struct literal syntax instead
988 // LL | const Y: X = X {};
990 // help: a constant with a similar name exists
992 // LL | const Y: X = Y("ö");
997 self.session.source_map().guess_head_span(def_span),
999 "similarly named {} `{}` defined here",
1000 suggestion.res.descr(),
1001 suggestion.candidate.as_str(),
1006 "{} {} with a similar name exists",
1007 suggestion.res.article(),
1008 suggestion.res.descr()
1010 err.span_suggestion(
1013 suggestion.candidate.to_string(),
1014 Applicability::MaybeIncorrect,
1019 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
1021 if b.span.is_dummy() {
1022 // These already contain the "built-in" prefix or look bad with it.
1024 !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);
1025 let (built_in, from) = if from_prelude {
1026 ("", " from prelude")
1027 } else if b.is_extern_crate()
1029 && self.session.opts.externs.get(&ident.as_str()).is_some()
1031 ("", " passed with `--extern`")
1032 } else if add_built_in {
1038 let a = if built_in.is_empty() { res.article() } else { "a" };
1039 format!("{a}{built_in} {thing}{from}", thing = res.descr())
1041 let introduced = if b.is_import() { "imported" } else { "defined" };
1042 format!("the {thing} {introduced} here", thing = res.descr())
1046 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
1047 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
1048 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
1049 // We have to print the span-less alternative first, otherwise formatting looks bad.
1050 (b2, b1, misc2, misc1, true)
1052 (b1, b2, misc1, misc2, false)
1055 let mut err = struct_span_err!(
1059 "`{ident}` is ambiguous ({why})",
1062 err.span_label(ident.span, "ambiguous name");
1064 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
1065 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
1066 let note_msg = format!("`{ident}` could{also} refer to {what}");
1068 let thing = b.res().descr();
1069 let mut help_msgs = Vec::new();
1070 if b.is_glob_import()
1071 && (kind == AmbiguityKind::GlobVsGlob
1072 || kind == AmbiguityKind::GlobVsExpanded
1073 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
1075 help_msgs.push(format!(
1076 "consider adding an explicit import of `{ident}` to disambiguate"
1079 if b.is_extern_crate() && ident.span.rust_2018() {
1080 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
1082 if misc == AmbiguityErrorMisc::SuggestCrate {
1084 .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously"))
1085 } else if misc == AmbiguityErrorMisc::SuggestSelf {
1087 .push(format!("use `self::{ident}` to refer to this {thing} unambiguously"))
1090 err.span_note(b.span, ¬e_msg);
1091 for (i, help_msg) in help_msgs.iter().enumerate() {
1092 let or = if i == 0 { "" } else { "or " };
1093 err.help(&format!("{}{}", or, help_msg));
1097 could_refer_to(b1, misc1, "");
1098 could_refer_to(b2, misc2, " also");
1102 /// If the binding refers to a tuple struct constructor with fields,
1103 /// returns the span of its fields.
1104 fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option<Span> {
1105 if let NameBindingKind::Res(
1106 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
1110 let def_id = self.parent(ctor_def_id).expect("no parent for a constructor");
1111 let fields = self.field_names.get(&def_id)?;
1112 return fields.iter().map(|name| name.span).reduce(Span::to); // None for `struct Foo()`
1117 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
1118 let PrivacyError { ident, binding, .. } = *privacy_error;
1120 let res = binding.res();
1121 let ctor_fields_span = self.ctor_fields_span(binding);
1122 let plain_descr = res.descr().to_string();
1123 let nonimport_descr =
1124 if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
1125 let import_descr = nonimport_descr.clone() + " import";
1127 |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
1129 // Print the primary message.
1130 let descr = get_descr(binding);
1132 struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident);
1133 err.span_label(ident.span, &format!("private {}", descr));
1134 if let Some(span) = ctor_fields_span {
1135 err.span_label(span, "a constructor is private if any of the fields is private");
1138 // Print the whole import chain to make it easier to see what happens.
1139 let first_binding = binding;
1140 let mut next_binding = Some(binding);
1141 let mut next_ident = ident;
1142 while let Some(binding) = next_binding {
1143 let name = next_ident;
1144 next_binding = match binding.kind {
1145 _ if res == Res::Err => None,
1146 NameBindingKind::Import { binding, import, .. } => match import.kind {
1147 _ if binding.span.is_dummy() => None,
1148 ImportKind::Single { source, .. } => {
1149 next_ident = source;
1152 ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding),
1153 ImportKind::ExternCrate { .. } => None,
1158 let first = ptr::eq(binding, first_binding);
1160 "{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
1161 and_refers_to = if first { "" } else { "...and refers to " },
1162 item = get_descr(binding),
1163 which = if first { "" } else { " which" },
1164 dots = if next_binding.is_some() { "..." } else { "" },
1166 let def_span = self.session.source_map().guess_head_span(binding.span);
1167 let mut note_span = MultiSpan::from_span(def_span);
1168 if !first && binding.vis == ty::Visibility::Public {
1169 note_span.push_span_label(def_span, "consider importing it directly".into());
1171 err.span_note(note_span, &msg);
1178 impl<'a, 'b> ImportResolver<'a, 'b> {
1179 /// Adds suggestions for a path that cannot be resolved.
1180 pub(crate) fn make_path_suggestion(
1183 mut path: Vec<Segment>,
1184 parent_scope: &ParentScope<'b>,
1185 ) -> Option<(Vec<Segment>, Vec<String>)> {
1186 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
1188 match (path.get(0), path.get(1)) {
1189 // `{{root}}::ident::...` on both editions.
1190 // On 2015 `{{root}}` is usually added implicitly.
1191 (Some(fst), Some(snd))
1192 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
1193 // `ident::...` on 2018.
1195 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
1197 // Insert a placeholder that's later replaced by `self`/`super`/etc.
1198 path.insert(0, Segment::from_ident(Ident::invalid()));
1203 self.make_missing_self_suggestion(span, path.clone(), parent_scope)
1204 .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
1205 .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
1206 .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
1209 /// Suggest a missing `self::` if that resolves to an correct module.
1213 /// LL | use foo::Bar;
1214 /// | ^^^ did you mean `self::foo`?
1216 fn make_missing_self_suggestion(
1219 mut path: Vec<Segment>,
1220 parent_scope: &ParentScope<'b>,
1221 ) -> Option<(Vec<Segment>, Vec<String>)> {
1222 // Replace first ident with `self` and check if that is valid.
1223 path[0].ident.name = kw::SelfLower;
1224 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1225 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1226 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1229 /// Suggests a missing `crate::` if that resolves to an correct module.
1233 /// LL | use foo::Bar;
1234 /// | ^^^ did you mean `crate::foo`?
1236 fn make_missing_crate_suggestion(
1239 mut path: Vec<Segment>,
1240 parent_scope: &ParentScope<'b>,
1241 ) -> Option<(Vec<Segment>, Vec<String>)> {
1242 // Replace first ident with `crate` and check if that is valid.
1243 path[0].ident.name = kw::Crate;
1244 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1245 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1246 if let PathResult::Module(..) = result {
1250 "`use` statements changed in Rust 2018; read more at \
1251 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1261 /// Suggests a missing `super::` if that resolves to an correct module.
1265 /// LL | use foo::Bar;
1266 /// | ^^^ did you mean `super::foo`?
1268 fn make_missing_super_suggestion(
1271 mut path: Vec<Segment>,
1272 parent_scope: &ParentScope<'b>,
1273 ) -> Option<(Vec<Segment>, Vec<String>)> {
1274 // Replace first ident with `crate` and check if that is valid.
1275 path[0].ident.name = kw::Super;
1276 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1277 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1278 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1281 /// Suggests a missing external crate name if that resolves to an correct module.
1285 /// LL | use foobar::Baz;
1286 /// | ^^^^^^ did you mean `baz::foobar`?
1289 /// Used when importing a submodule of an external crate but missing that crate's
1290 /// name as the first part of path.
1291 fn make_external_crate_suggestion(
1294 mut path: Vec<Segment>,
1295 parent_scope: &ParentScope<'b>,
1296 ) -> Option<(Vec<Segment>, Vec<String>)> {
1297 if path[1].ident.span.rust_2015() {
1301 // Sort extern crate names in reverse order to get
1302 // 1) some consistent ordering for emitted diagnostics, and
1303 // 2) `std` suggestions before `core` suggestions.
1304 let mut extern_crate_names =
1305 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1306 extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
1308 for name in extern_crate_names.into_iter() {
1309 // Replace first ident with a crate name and check if that is valid.
1310 path[0].ident.name = name;
1311 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1313 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1316 if let PathResult::Module(..) = result {
1317 return Some((path, Vec::new()));
1324 /// Suggests importing a macro from the root of the crate rather than a module within
1328 /// help: a macro with this name exists at the root of the crate
1330 /// LL | use issue_59764::makro;
1331 /// | ^^^^^^^^^^^^^^^^^^
1333 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1334 /// at the root of the crate instead of the module where it is defined
1336 pub(crate) fn check_for_module_export_macro(
1338 import: &'b Import<'b>,
1339 module: ModuleOrUniformRoot<'b>,
1341 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1342 let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
1348 while let Some(parent) = crate_module.parent {
1349 crate_module = parent;
1352 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1353 // Don't make a suggestion if the import was already from the root of the
1358 let resolutions = self.r.resolutions(crate_module).borrow();
1359 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1360 let binding = resolution.borrow().binding()?;
1361 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1362 let module_name = crate_module.kind.name().unwrap();
1363 let import_snippet = match import.kind {
1364 ImportKind::Single { source, target, .. } if source != target => {
1365 format!("{} as {}", source, target)
1367 _ => format!("{}", ident),
1370 let mut corrections: Vec<(Span, String)> = Vec::new();
1371 if !import.is_nested() {
1372 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1373 // intermediate segments.
1374 corrections.push((import.span, format!("{}::{}", module_name, import_snippet)));
1376 // Find the binding span (and any trailing commas and spaces).
1377 // ie. `use a::b::{c, d, e};`
1379 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1385 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1386 found_closing_brace, binding_span
1389 let mut removal_span = binding_span;
1390 if found_closing_brace {
1391 // If the binding span ended with a closing brace, as in the below example:
1392 // ie. `use a::b::{c, d};`
1394 // Then expand the span of characters to remove to include the previous
1395 // binding's trailing comma.
1396 // ie. `use a::b::{c, d};`
1398 if let Some(previous_span) =
1399 extend_span_to_previous_binding(self.r.session, binding_span)
1401 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1402 removal_span = removal_span.with_lo(previous_span.lo());
1405 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1407 // Remove the `removal_span`.
1408 corrections.push((removal_span, "".to_string()));
1410 // Find the span after the crate name and if it has nested imports immediatately
1411 // after the crate name already.
1412 // ie. `use a::b::{c, d};`
1414 // or `use a::{b, c, d}};`
1416 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1422 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1423 has_nested, after_crate_name
1426 let source_map = self.r.session.source_map();
1428 // Add the import to the start, with a `{` if required.
1429 let start_point = source_map.start_point(after_crate_name);
1430 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1434 // In this case, `start_snippet` must equal '{'.
1435 format!("{}{}, ", start_snippet, import_snippet)
1437 // In this case, add a `{`, then the moved import, then whatever
1438 // was there before.
1439 format!("{{{}, {}", import_snippet, start_snippet)
1444 // Add a `};` to the end if nested, matching the `{` added at the start.
1446 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1450 let suggestion = Some((
1452 String::from("a macro with this name exists at the root of the crate"),
1453 Applicability::MaybeIncorrect,
1456 "this could be because a macro annotated with `#[macro_export]` will be exported \
1457 at the root of the crate instead of the module where it is defined"
1460 Some((suggestion, note))
1467 /// Given a `binding_span` of a binding within a use statement:
1470 /// use foo::{a, b, c};
1474 /// then return the span until the next binding or the end of the statement:
1477 /// use foo::{a, b, c};
1480 pub(crate) fn find_span_of_binding_until_next_binding(
1485 let source_map = sess.source_map();
1487 // Find the span of everything after the binding.
1488 // ie. `a, e};` or `a};`
1489 let binding_until_end = binding_span.with_hi(use_span.hi());
1491 // Find everything after the binding but not including the binding.
1492 // ie. `, e};` or `};`
1493 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1495 // Keep characters in the span until we encounter something that isn't a comma or
1499 // Also note whether a closing brace character was encountered. If there
1500 // was, then later go backwards to remove any trailing commas that are left.
1501 let mut found_closing_brace = false;
1502 let after_binding_until_next_binding =
1503 source_map.span_take_while(after_binding_until_end, |&ch| {
1505 found_closing_brace = true;
1507 ch == ' ' || ch == ','
1510 // Combine the two spans.
1511 // ie. `a, ` or `a`.
1513 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1514 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1516 (found_closing_brace, span)
1519 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1523 /// use foo::a::{a, b, c};
1524 /// ^^--- binding span
1528 /// use foo::{a, b, c};
1529 /// --- binding span
1531 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1532 let source_map = sess.source_map();
1534 // `prev_source` will contain all of the source that came before the span.
1535 // Then split based on a command and take the first (ie. closest to our span)
1536 // snippet. In the example, this is a space.
1537 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1539 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1540 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1541 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1545 let prev_comma = prev_comma.first().unwrap();
1546 let prev_starting_brace = prev_starting_brace.first().unwrap();
1548 // If the amount of source code before the comma is greater than
1549 // the amount of source code before the starting brace then we've only
1550 // got one item in the nested item (eg. `issue_52891::{self}`).
1551 if prev_comma.len() > prev_starting_brace.len() {
1555 Some(binding_span.with_lo(BytePos(
1556 // Take away the number of bytes for the characters we've found and an
1557 // extra for the comma.
1558 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1562 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1563 /// it is a nested use tree.
1566 /// use foo::a::{b, c};
1567 /// ^^^^^^^^^^ // false
1569 /// use foo::{a, b, c};
1570 /// ^^^^^^^^^^ // true
1572 /// use foo::{a, b::{c, d}};
1573 /// ^^^^^^^^^^^^^^^ // true
1575 fn find_span_immediately_after_crate_name(
1577 module_name: Symbol,
1581 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1582 module_name, use_span
1584 let source_map = sess.source_map();
1586 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1587 let mut num_colons = 0;
1588 // Find second colon.. `use issue_59764:`
1589 let until_second_colon = source_map.span_take_while(use_span, |c| {
1593 !matches!(c, ':' if num_colons == 2)
1595 // Find everything after the second colon.. `foo::{baz, makro};`
1596 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1598 let mut found_a_non_whitespace_character = false;
1599 // Find the first non-whitespace character in `from_second_colon`.. `f`
1600 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1601 if found_a_non_whitespace_character {
1604 if !c.is_whitespace() {
1605 found_a_non_whitespace_character = true;
1610 // Find the first `{` in from_second_colon.. `foo::{`
1611 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1613 (next_left_bracket == after_second_colon, from_second_colon)
1616 /// When an entity with a given name is not available in scope, we search for
1617 /// entities with that name in all crates. This method allows outputting the
1618 /// results of this search in a programmer-friendly way
1619 crate fn show_candidates(
1620 err: &mut DiagnosticBuilder<'_>,
1621 // This is `None` if all placement locations are inside expansions
1622 use_placement_span: Option<Span>,
1623 candidates: &[ImportSuggestion],
1627 if candidates.is_empty() {
1631 // we want consistent results across executions, but candidates are produced
1632 // by iterating through a hash map, so make sure they are ordered:
1633 let mut path_strings: Vec<_> =
1634 candidates.iter().map(|c| path_names_to_string(&c.path)).collect();
1636 path_strings.sort();
1637 path_strings.dedup();
1639 let (determiner, kind) = if candidates.len() == 1 {
1640 ("this", candidates[0].descr)
1642 ("one of these", "items")
1645 let instead = if instead { " instead" } else { "" };
1646 let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
1648 if let Some(span) = use_placement_span {
1649 for candidate in &mut path_strings {
1650 // produce an additional newline to separate the new use statement
1651 // from the directly following item.
1652 let additional_newline = if found_use { "" } else { "\n" };
1653 *candidate = format!("use {};\n{}", candidate, additional_newline);
1656 err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
1660 for candidate in path_strings {
1662 msg.push_str(&candidate);