5 use rustc_ast::ast::{self, Path};
6 use rustc_ast::util::lev_distance::find_best_match_for_name;
7 use rustc_ast_pretty::pprust;
8 use rustc_data_structures::fx::FxHashSet;
9 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
10 use rustc_feature::BUILTIN_ATTRIBUTES;
11 use rustc_hir::def::Namespace::{self, *};
12 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
13 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
14 use rustc_middle::bug;
15 use rustc_middle::ty::{self, DefIdTree};
16 use rustc_session::Session;
17 use rustc_span::hygiene::MacroKind;
18 use rustc_span::source_map::SourceMap;
19 use rustc_span::symbol::{kw, sym, Ident, Symbol};
20 use rustc_span::{BytePos, MultiSpan, Span};
22 use crate::imports::{Import, ImportKind, ImportResolver};
23 use crate::path_names_to_string;
24 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
26 BindingError, CrateLint, HasGenericParams, MacroRulesScope, Module, ModuleOrUniformRoot,
28 use crate::{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 struct TypoSuggestion {
41 pub candidate: Symbol,
46 crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
47 TypoSuggestion { candidate, res }
51 /// A free importable items suggested in case of resolution failure.
52 crate struct ImportSuggestion {
53 pub did: Option<DefId>,
54 pub descr: &'static str,
59 /// Adjust the impl span so that just the `impl` keyword is taken by removing
60 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
61 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
63 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
64 /// parser. If you need to use this function or something similar, please consider updating the
65 /// `source_map` functions and this function to something more robust.
66 fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
67 let impl_span = sm.span_until_char(impl_span, '<');
68 sm.span_until_whitespace(impl_span)
71 impl<'a> Resolver<'a> {
72 crate fn add_module_candidates(
75 names: &mut Vec<TypoSuggestion>,
76 filter_fn: &impl Fn(Res) -> bool,
78 for (key, resolution) in self.resolutions(module).borrow().iter() {
79 if let Some(binding) = resolution.borrow().binding {
80 let res = binding.res();
82 names.push(TypoSuggestion::from_res(key.ident.name, res));
88 /// Combines an error with provided span and emits it.
90 /// This takes the error provided, combines it with the span and any additional spans inside the
91 /// error and emits it.
92 crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
93 self.into_struct_error(span, resolution_error).emit();
96 crate fn into_struct_error(
99 resolution_error: ResolutionError<'_>,
100 ) -> DiagnosticBuilder<'_> {
101 match resolution_error {
102 ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
103 let mut err = struct_span_err!(
107 "can't use generic parameters from outer function",
109 err.span_label(span, "use of generic parameter from outer function".to_string());
111 let sm = self.session.source_map();
113 Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => {
114 if let Some(impl_span) =
115 maybe_impl_defid.and_then(|def_id| self.opt_span(def_id))
118 reduce_impl_span_to_impl_keyword(sm, impl_span),
119 "`Self` type implicitly declared here, by this `impl`",
122 match (maybe_trait_defid, maybe_impl_defid) {
124 err.span_label(span, "can't use `Self` here");
127 err.span_label(span, "use a type here instead");
129 (None, None) => bug!("`impl` without trait nor type?"),
133 Res::Def(DefKind::TyParam, def_id) => {
134 if let Some(span) = self.opt_span(def_id) {
135 err.span_label(span, "type parameter from outer function");
138 Res::Def(DefKind::ConstParam, def_id) => {
139 if let Some(span) = self.opt_span(def_id) {
140 err.span_label(span, "const parameter from outer function");
145 "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
151 if has_generic_params == HasGenericParams::Yes {
152 // Try to retrieve the span of the function signature and generate a new
153 // message with a local type or const parameter.
154 let sugg_msg = "try using a local generic parameter instead";
155 if let Some((sugg_span, snippet)) = sm.generate_local_type_param_snippet(span) {
156 // Suggest the modification to the user
161 Applicability::MachineApplicable,
163 } else if let Some(sp) = sm.generate_fn_name_span(span) {
166 "try adding a local generic parameter in this method instead"
170 err.help("try using a local generic parameter instead");
176 ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
177 let mut err = struct_span_err!(
181 "the name `{}` is already used for a generic \
182 parameter in this item's generic parameters",
185 err.span_label(span, "already used");
186 err.span_label(first_use_span, format!("first use of `{}`", name));
189 ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
190 let mut err = struct_span_err!(
194 "method `{}` is not a member of trait `{}`",
198 err.span_label(span, format!("not a member of trait `{}`", trait_));
201 ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
202 let mut err = struct_span_err!(
206 "type `{}` is not a member of trait `{}`",
210 err.span_label(span, format!("not a member of trait `{}`", trait_));
213 ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
214 let mut err = struct_span_err!(
218 "const `{}` is not a member of trait `{}`",
222 err.span_label(span, format!("not a member of trait `{}`", trait_));
225 ResolutionError::VariableNotBoundInPattern(binding_error) => {
226 let BindingError { name, target, origin, could_be_path } = binding_error;
228 let target_sp = target.iter().copied().collect::<Vec<_>>();
229 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
231 let msp = MultiSpan::from_spans(target_sp.clone());
232 let mut err = struct_span_err!(
236 "variable `{}` is not bound in all patterns",
239 for sp in target_sp {
240 err.span_label(sp, format!("pattern doesn't bind `{}`", name));
242 for sp in origin_sp {
243 err.span_label(sp, "variable not in all patterns");
246 let help_msg = format!(
247 "if you meant to match on a variant or a `const` item, consider \
248 making the path in the pattern qualified: `?::{}`",
251 err.span_help(span, &help_msg);
255 ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
256 let mut err = struct_span_err!(
260 "variable `{}` is bound inconsistently across alternatives separated by `|`",
263 err.span_label(span, "bound in different ways");
264 err.span_label(first_binding_span, "first binding");
267 ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
268 let mut err = struct_span_err!(
272 "identifier `{}` is bound more than once in this parameter list",
275 err.span_label(span, "used as parameter more than once");
278 ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
279 let mut err = struct_span_err!(
283 "identifier `{}` is bound more than once in the same pattern",
286 err.span_label(span, "used in a pattern more than once");
289 ResolutionError::UndeclaredLabel { name, suggestion } => {
290 let mut err = struct_span_err!(
294 "use of undeclared label `{}`",
298 err.span_label(span, format!("undeclared label `{}`", name));
301 // A reachable label with a similar name exists.
302 Some((ident, true)) => {
303 err.span_label(ident.span, "a label with a similar name is reachable");
306 "try using similarly named label",
307 ident.name.to_string(),
308 Applicability::MaybeIncorrect,
311 // An unreachable label with a similar name exists.
312 Some((ident, false)) => {
315 "a label with a similar name exists but is unreachable",
318 // No similarly-named labels exist.
324 ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
325 let mut err = struct_span_err!(
330 "`self` imports are only allowed within a { } list"
333 // None of the suggestions below would help with a case like `use self`.
335 // use foo::bar::self -> foo::bar
336 // use foo::bar::self as abc -> foo::bar as abc
339 "consider importing the module directly",
341 Applicability::MachineApplicable,
344 // use foo::bar::self -> foo::bar::{self}
345 // use foo::bar::self as abc -> foo::bar::{self as abc}
347 (span_with_rename.shrink_to_lo(), "{".to_string()),
348 (span_with_rename.shrink_to_hi(), "}".to_string()),
350 err.multipart_suggestion(
351 "alternatively, use the multi-path `use` syntax to import `self`",
353 Applicability::MachineApplicable,
358 ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
359 let mut err = struct_span_err!(
363 "`self` import can only appear once in an import list"
365 err.span_label(span, "can only appear once in an import list");
368 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
369 let mut err = struct_span_err!(
373 "`self` import can only appear in an import list with \
376 err.span_label(span, "can only appear in an import list with a non-empty prefix");
379 ResolutionError::FailedToResolve { label, suggestion } => {
381 struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
382 err.span_label(span, label);
384 if let Some((suggestions, msg, applicability)) = suggestion {
385 err.multipart_suggestion(&msg, suggestions, applicability);
390 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
391 let mut err = struct_span_err!(
396 "can't capture dynamic environment in a fn item"
398 err.help("use the `|| { ... }` closure form instead");
401 ResolutionError::AttemptToUseNonConstantValueInConstant => {
402 let mut err = struct_span_err!(
406 "attempt to use a non-constant value in a constant"
408 err.span_label(span, "non-constant value");
411 ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
412 let res = binding.res();
413 let shadows_what = res.descr();
414 let mut err = struct_span_err!(
418 "{}s cannot shadow {}s",
424 format!("cannot be named the same as {} {}", res.article(), shadows_what),
426 let participle = if binding.is_import() { "imported" } else { "defined" };
427 let msg = format!("the {} `{}` is {} here", shadows_what, name, participle);
428 err.span_label(binding.span, msg);
431 ResolutionError::ForwardDeclaredTyParam => {
432 let mut err = struct_span_err!(
436 "type parameters with a default cannot use \
437 forward declared identifiers"
441 "defaulted type parameters cannot be forward declared".to_string(),
445 ResolutionError::ParamInTyOfConstParam(name) => {
446 let mut err = struct_span_err!(
450 "the type of const parameters must not depend on other generic parameters"
454 format!("the type must not depend on the parameter `{}`", name),
458 ResolutionError::ParamInAnonConstInTyDefault(name) => {
459 let mut err = self.session.struct_span_err(
461 "constant values inside of type parameter defaults must not depend on generic parameters",
465 format!("the anonymous constant must not depend on the parameter `{}`", name),
469 ResolutionError::SelfInTyParamDefault => {
470 let mut err = struct_span_err!(
474 "type parameters cannot use `Self` in their defaults"
476 err.span_label(span, "`Self` in type parameter default".to_string());
479 ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
480 let mut err = struct_span_err!(
484 "use of unreachable label `{}`",
488 err.span_label(definition_span, "unreachable label defined here");
489 err.span_label(span, format!("unreachable label `{}`", name));
491 "labels are unreachable through functions, closures, async blocks and modules",
495 // A reachable label with a similar name exists.
496 Some((ident, true)) => {
497 err.span_label(ident.span, "a label with a similar name is reachable");
500 "try using similarly named label",
501 ident.name.to_string(),
502 Applicability::MaybeIncorrect,
505 // An unreachable label with a similar name exists.
506 Some((ident, false)) => {
509 "a label with a similar name exists but is also unreachable",
512 // No similarly-named labels exist.
521 crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
522 match vis_resolution_error {
523 VisResolutionError::Relative2018(span, path) => {
524 let mut err = self.session.struct_span_err(
526 "relative paths are not supported in visibilities on 2018 edition",
531 format!("crate::{}", pprust::path_to_string(&path)),
532 Applicability::MaybeIncorrect,
536 VisResolutionError::AncestorOnly(span) => struct_span_err!(
540 "visibilities can only be restricted to ancestor modules"
542 VisResolutionError::FailedToResolve(span, label, suggestion) => {
543 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
545 VisResolutionError::ExpectedFound(span, path_str, res) => {
546 let mut err = struct_span_err!(
550 "expected module, found {} `{}`",
554 err.span_label(span, "not a module");
557 VisResolutionError::Indeterminate(span) => struct_span_err!(
561 "cannot determine resolution for the visibility"
563 VisResolutionError::ModuleOnly(span) => {
564 self.session.struct_span_err(span, "visibility must resolve to a module")
570 /// Lookup typo candidate in scope for a macro or import.
571 fn early_lookup_typo_candidate(
574 parent_scope: &ParentScope<'a>,
576 filter_fn: &impl Fn(Res) -> bool,
577 ) -> Option<TypoSuggestion> {
578 let mut suggestions = Vec::new();
579 self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
581 Scope::DeriveHelpers(expn_id) => {
582 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
589 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
593 Scope::DeriveHelpersCompat => {
594 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
596 for derive in parent_scope.derives {
597 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
598 if let Ok((Some(ext), _)) = this.resolve_macro_path(
600 Some(MacroKind::Derive),
608 .map(|name| TypoSuggestion::from_res(*name, res)),
614 Scope::MacroRules(macro_rules_scope) => {
615 if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope {
616 let res = macro_rules_binding.binding.res();
619 .push(TypoSuggestion::from_res(macro_rules_binding.ident.name, res))
623 Scope::CrateRoot => {
624 let root_ident = Ident::new(kw::PathRoot, ident.span);
625 let root_module = this.resolve_crate_root(root_ident);
626 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
628 Scope::Module(module) => {
629 this.add_module_candidates(module, &mut suggestions, filter_fn);
631 Scope::RegisteredAttrs => {
632 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
635 this.registered_attrs
637 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
641 Scope::MacroUsePrelude => {
642 suggestions.extend(this.macro_use_prelude.iter().filter_map(
644 let res = binding.res();
645 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
649 Scope::BuiltinAttrs => {
650 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
655 .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
659 Scope::ExternPrelude => {
660 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
661 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
662 filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
665 Scope::ToolPrelude => {
666 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
668 this.registered_tools
670 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
673 Scope::StdLibPrelude => {
674 if let Some(prelude) = this.prelude {
675 let mut tmp_suggestions = Vec::new();
676 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
680 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
684 Scope::BuiltinTypes => {
685 let primitive_types = &this.primitive_type_table.primitive_types;
686 suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| {
687 let res = Res::PrimTy(*prim_ty);
688 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
696 // Make sure error reporting is deterministic.
697 suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
699 match find_best_match_for_name(
700 suggestions.iter().map(|suggestion| &suggestion.candidate),
704 Some(found) if found != ident.name => {
705 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
711 fn lookup_import_candidates_from_module<FilterFn>(
714 namespace: Namespace,
715 parent_scope: &ParentScope<'a>,
716 start_module: Module<'a>,
719 ) -> Vec<ImportSuggestion>
721 FilterFn: Fn(Res) -> bool,
723 let mut candidates = Vec::new();
724 let mut seen_modules = FxHashSet::default();
725 let not_local_module = crate_name.name != kw::Crate;
727 vec![(start_module, Vec::<ast::PathSegment>::new(), true, not_local_module)];
728 let mut worklist_via_import = vec![];
730 while let Some((in_module, path_segments, accessible, in_module_is_extern)) =
731 match worklist.pop() {
732 None => worklist_via_import.pop(),
736 // We have to visit module children in deterministic order to avoid
737 // instabilities in reported imports (#43552).
738 in_module.for_each_child(self, |this, ident, ns, name_binding| {
739 // avoid non-importable candidates
740 if !name_binding.is_importable() {
744 let child_accessible =
745 accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
747 // do not venture inside inaccessible items of other crates
748 if in_module_is_extern && !child_accessible {
752 let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
754 // There is an assumption elsewhere that paths of variants are in the enum's
755 // declaration and not imported. With this assumption, the variant component is
756 // chopped and the rest of the path is assumed to be the enum's own path. For
757 // errors where a variant is used as the type instead of the enum, this causes
758 // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
759 if via_import && name_binding.is_possibly_imported_variant() {
763 // collect results based on the filter function
764 // avoid suggesting anything from the same module in which we are resolving
765 if ident.name == lookup_ident.name
767 && !ptr::eq(in_module, parent_scope.module)
769 let res = name_binding.res();
772 let mut segms = path_segments.clone();
773 if lookup_ident.span.rust_2018() {
774 // crate-local absolute paths start with `crate::` in edition 2018
775 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
776 segms.insert(0, ast::PathSegment::from_ident(crate_name));
779 segms.push(ast::PathSegment::from_ident(ident));
780 let path = Path { span: name_binding.span, segments: segms };
781 let did = match res {
782 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
783 _ => res.opt_def_id(),
786 if child_accessible {
787 // Remove invisible match if exists
788 if let Some(idx) = candidates
790 .position(|v: &ImportSuggestion| v.did == did && !v.accessible)
792 candidates.remove(idx);
796 if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
797 candidates.push(ImportSuggestion {
801 accessible: child_accessible,
807 // collect submodules to explore
808 if let Some(module) = name_binding.module() {
810 let mut path_segments = path_segments.clone();
811 path_segments.push(ast::PathSegment::from_ident(ident));
813 let is_extern_crate_that_also_appears_in_prelude =
814 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
816 if !is_extern_crate_that_also_appears_in_prelude {
817 let is_extern = in_module_is_extern || name_binding.is_extern_crate();
818 // add the module to the lookup
819 if seen_modules.insert(module.def_id().unwrap()) {
820 if via_import { &mut worklist_via_import } else { &mut worklist }
821 .push((module, path_segments, child_accessible, is_extern));
828 // If only some candidates are accessible, take just them
829 if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
830 candidates = candidates.into_iter().filter(|x| x.accessible).collect();
836 /// When name resolution fails, this method can be used to look up candidate
837 /// entities with the expected name. It allows filtering them using the
838 /// supplied predicate (which should be used to only accept the types of
839 /// definitions expected, e.g., traits). The lookup spans across all crates.
841 /// N.B., the method does not look into imports, but this is not a problem,
842 /// since we report the definitions (thus, the de-aliased imports).
843 crate fn lookup_import_candidates<FilterFn>(
846 namespace: Namespace,
847 parent_scope: &ParentScope<'a>,
849 ) -> Vec<ImportSuggestion>
851 FilterFn: Fn(Res) -> bool,
853 let mut suggestions = self.lookup_import_candidates_from_module(
858 Ident::with_dummy_span(kw::Crate),
862 if lookup_ident.span.rust_2018() {
863 let extern_prelude_names = self.extern_prelude.clone();
864 for (ident, _) in extern_prelude_names.into_iter() {
865 if ident.span.from_expansion() {
866 // Idents are adjusted to the root context before being
867 // resolved in the extern prelude, so reporting this to the
868 // user is no help. This skips the injected
869 // `extern crate std` in the 2018 edition, which would
870 // otherwise cause duplicate suggestions.
873 if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
875 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
876 suggestions.extend(self.lookup_import_candidates_from_module(
891 crate fn unresolved_macro_suggestions(
893 err: &mut DiagnosticBuilder<'a>,
894 macro_kind: MacroKind,
895 parent_scope: &ParentScope<'a>,
898 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
899 let suggestion = self.early_lookup_typo_candidate(
900 ScopeSet::Macro(macro_kind),
905 self.add_typo_suggestion(err, suggestion, ident.span);
907 if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
908 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
909 err.span_note(ident.span, &msg);
911 if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
912 err.help("have you added the `#[macro_use]` on the module/import?");
916 crate fn add_typo_suggestion(
918 err: &mut DiagnosticBuilder<'_>,
919 suggestion: Option<TypoSuggestion>,
922 let suggestion = match suggestion {
923 None => return false,
924 // We shouldn't suggest underscore.
925 Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
926 Some(suggestion) => suggestion,
929 "{} {} with a similar name exists",
930 suggestion.res.article(),
931 suggestion.res.descr()
936 suggestion.candidate.to_string(),
937 Applicability::MaybeIncorrect,
939 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
940 LOCAL_CRATE => self.opt_span(def_id),
944 .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
947 if let Some(span) = def_span {
949 self.session.source_map().guess_head_span(span),
951 "similarly named {} `{}` defined here",
952 suggestion.res.descr(),
953 suggestion.candidate.as_str(),
960 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
962 if b.span.is_dummy() {
963 let add_built_in = match b.res() {
964 // These already contain the "built-in" prefix or look bad with it.
965 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
968 let (built_in, from) = if from_prelude {
969 ("", " from prelude")
970 } else if b.is_extern_crate()
972 && self.session.opts.externs.get(&ident.as_str()).is_some()
974 ("", " passed with `--extern`")
975 } else if add_built_in {
981 let article = if built_in.is_empty() { res.article() } else { "a" };
983 "{a}{built_in} {thing}{from}",
990 let introduced = if b.is_import() { "imported" } else { "defined" };
991 format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced)
995 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
996 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
997 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
998 // We have to print the span-less alternative first, otherwise formatting looks bad.
999 (b2, b1, misc2, misc1, true)
1001 (b1, b2, misc1, misc2, false)
1004 let mut err = struct_span_err!(
1008 "`{ident}` is ambiguous ({why})",
1012 err.span_label(ident.span, "ambiguous name");
1014 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
1015 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
1016 let note_msg = format!(
1017 "`{ident}` could{also} refer to {what}",
1023 let thing = b.res().descr();
1024 let mut help_msgs = Vec::new();
1025 if b.is_glob_import()
1026 && (kind == AmbiguityKind::GlobVsGlob
1027 || kind == AmbiguityKind::GlobVsExpanded
1028 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
1030 help_msgs.push(format!(
1031 "consider adding an explicit import of \
1032 `{ident}` to disambiguate",
1036 if b.is_extern_crate() && ident.span.rust_2018() {
1037 help_msgs.push(format!(
1038 "use `::{ident}` to refer to this {thing} unambiguously",
1043 if misc == AmbiguityErrorMisc::SuggestCrate {
1044 help_msgs.push(format!(
1045 "use `crate::{ident}` to refer to this {thing} unambiguously",
1049 } else if misc == AmbiguityErrorMisc::SuggestSelf {
1050 help_msgs.push(format!(
1051 "use `self::{ident}` to refer to this {thing} unambiguously",
1057 err.span_note(b.span, ¬e_msg);
1058 for (i, help_msg) in help_msgs.iter().enumerate() {
1059 let or = if i == 0 { "" } else { "or " };
1060 err.help(&format!("{}{}", or, help_msg));
1064 could_refer_to(b1, misc1, "");
1065 could_refer_to(b2, misc2, " also");
1069 /// If the binding refers to a tuple struct constructor with fields,
1070 /// returns the span of its fields.
1071 fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option<Span> {
1072 if let NameBindingKind::Res(
1073 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
1077 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
1078 if let Some(fields) = self.field_names.get(&def_id) {
1079 let first_field = fields.first().expect("empty field list in the map");
1080 return Some(fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)));
1086 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
1087 let PrivacyError { ident, binding, .. } = *privacy_error;
1089 let res = binding.res();
1090 let ctor_fields_span = self.ctor_fields_span(binding);
1091 let plain_descr = res.descr().to_string();
1092 let nonimport_descr =
1093 if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
1094 let import_descr = nonimport_descr.clone() + " import";
1096 |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
1098 // Print the primary message.
1099 let descr = get_descr(binding);
1101 struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident);
1102 err.span_label(ident.span, &format!("private {}", descr));
1103 if let Some(span) = ctor_fields_span {
1104 err.span_label(span, "a constructor is private if any of the fields is private");
1107 // Print the whole import chain to make it easier to see what happens.
1108 let first_binding = binding;
1109 let mut next_binding = Some(binding);
1110 let mut next_ident = ident;
1111 while let Some(binding) = next_binding {
1112 let name = next_ident;
1113 next_binding = match binding.kind {
1114 _ if res == Res::Err => None,
1115 NameBindingKind::Import { binding, import, .. } => match import.kind {
1116 _ if binding.span.is_dummy() => None,
1117 ImportKind::Single { source, .. } => {
1118 next_ident = source;
1121 ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding),
1122 ImportKind::ExternCrate { .. } => None,
1127 let first = ptr::eq(binding, first_binding);
1128 let descr = get_descr(binding);
1130 "{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
1131 and_refers_to = if first { "" } else { "...and refers to " },
1134 which = if first { "" } else { " which" },
1135 dots = if next_binding.is_some() { "..." } else { "" },
1137 let def_span = self.session.source_map().guess_head_span(binding.span);
1138 let mut note_span = MultiSpan::from_span(def_span);
1139 if !first && binding.vis == ty::Visibility::Public {
1140 note_span.push_span_label(def_span, "consider importing it directly".into());
1142 err.span_note(note_span, &msg);
1149 impl<'a, 'b> ImportResolver<'a, 'b> {
1150 /// Adds suggestions for a path that cannot be resolved.
1151 pub(crate) fn make_path_suggestion(
1154 mut path: Vec<Segment>,
1155 parent_scope: &ParentScope<'b>,
1156 ) -> Option<(Vec<Segment>, Vec<String>)> {
1157 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
1159 match (path.get(0), path.get(1)) {
1160 // `{{root}}::ident::...` on both editions.
1161 // On 2015 `{{root}}` is usually added implicitly.
1162 (Some(fst), Some(snd))
1163 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
1164 // `ident::...` on 2018.
1166 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
1168 // Insert a placeholder that's later replaced by `self`/`super`/etc.
1169 path.insert(0, Segment::from_ident(Ident::invalid()));
1174 self.make_missing_self_suggestion(span, path.clone(), parent_scope)
1175 .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
1176 .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
1177 .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
1180 /// Suggest a missing `self::` if that resolves to an correct module.
1184 /// LL | use foo::Bar;
1185 /// | ^^^ did you mean `self::foo`?
1187 fn make_missing_self_suggestion(
1190 mut path: Vec<Segment>,
1191 parent_scope: &ParentScope<'b>,
1192 ) -> Option<(Vec<Segment>, Vec<String>)> {
1193 // Replace first ident with `self` and check if that is valid.
1194 path[0].ident.name = kw::SelfLower;
1195 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1196 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1197 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1200 /// Suggests a missing `crate::` if that resolves to an correct module.
1204 /// LL | use foo::Bar;
1205 /// | ^^^ did you mean `crate::foo`?
1207 fn make_missing_crate_suggestion(
1210 mut path: Vec<Segment>,
1211 parent_scope: &ParentScope<'b>,
1212 ) -> Option<(Vec<Segment>, Vec<String>)> {
1213 // Replace first ident with `crate` and check if that is valid.
1214 path[0].ident.name = kw::Crate;
1215 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1216 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1217 if let PathResult::Module(..) = result {
1221 "`use` statements changed in Rust 2018; read more at \
1222 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1232 /// Suggests a missing `super::` if that resolves to an correct module.
1236 /// LL | use foo::Bar;
1237 /// | ^^^ did you mean `super::foo`?
1239 fn make_missing_super_suggestion(
1242 mut path: Vec<Segment>,
1243 parent_scope: &ParentScope<'b>,
1244 ) -> Option<(Vec<Segment>, Vec<String>)> {
1245 // Replace first ident with `crate` and check if that is valid.
1246 path[0].ident.name = kw::Super;
1247 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1248 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1249 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1252 /// Suggests a missing external crate name if that resolves to an correct module.
1256 /// LL | use foobar::Baz;
1257 /// | ^^^^^^ did you mean `baz::foobar`?
1260 /// Used when importing a submodule of an external crate but missing that crate's
1261 /// name as the first part of path.
1262 fn make_external_crate_suggestion(
1265 mut path: Vec<Segment>,
1266 parent_scope: &ParentScope<'b>,
1267 ) -> Option<(Vec<Segment>, Vec<String>)> {
1268 if path[1].ident.span.rust_2015() {
1272 // Sort extern crate names in reverse order to get
1273 // 1) some consistent ordering for emitted diagnostics, and
1274 // 2) `std` suggestions before `core` suggestions.
1275 let mut extern_crate_names =
1276 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1277 extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
1279 for name in extern_crate_names.into_iter() {
1280 // Replace first ident with a crate name and check if that is valid.
1281 path[0].ident.name = name;
1282 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1284 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1287 if let PathResult::Module(..) = result {
1288 return Some((path, Vec::new()));
1295 /// Suggests importing a macro from the root of the crate rather than a module within
1299 /// help: a macro with this name exists at the root of the crate
1301 /// LL | use issue_59764::makro;
1302 /// | ^^^^^^^^^^^^^^^^^^
1304 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1305 /// at the root of the crate instead of the module where it is defined
1307 pub(crate) fn check_for_module_export_macro(
1309 import: &'b Import<'b>,
1310 module: ModuleOrUniformRoot<'b>,
1312 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1313 let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
1319 while let Some(parent) = crate_module.parent {
1320 crate_module = parent;
1323 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1324 // Don't make a suggestion if the import was already from the root of the
1329 let resolutions = self.r.resolutions(crate_module).borrow();
1330 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1331 let binding = resolution.borrow().binding()?;
1332 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1333 let module_name = crate_module.kind.name().unwrap();
1334 let import_snippet = match import.kind {
1335 ImportKind::Single { source, target, .. } if source != target => {
1336 format!("{} as {}", source, target)
1338 _ => format!("{}", ident),
1341 let mut corrections: Vec<(Span, String)> = Vec::new();
1342 if !import.is_nested() {
1343 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1344 // intermediate segments.
1345 corrections.push((import.span, format!("{}::{}", module_name, import_snippet)));
1347 // Find the binding span (and any trailing commas and spaces).
1348 // ie. `use a::b::{c, d, e};`
1350 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1356 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1357 found_closing_brace, binding_span
1360 let mut removal_span = binding_span;
1361 if found_closing_brace {
1362 // If the binding span ended with a closing brace, as in the below example:
1363 // ie. `use a::b::{c, d};`
1365 // Then expand the span of characters to remove to include the previous
1366 // binding's trailing comma.
1367 // ie. `use a::b::{c, d};`
1369 if let Some(previous_span) =
1370 extend_span_to_previous_binding(self.r.session, binding_span)
1372 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1373 removal_span = removal_span.with_lo(previous_span.lo());
1376 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1378 // Remove the `removal_span`.
1379 corrections.push((removal_span, "".to_string()));
1381 // Find the span after the crate name and if it has nested imports immediatately
1382 // after the crate name already.
1383 // ie. `use a::b::{c, d};`
1385 // or `use a::{b, c, d}};`
1387 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1393 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1394 has_nested, after_crate_name
1397 let source_map = self.r.session.source_map();
1399 // Add the import to the start, with a `{` if required.
1400 let start_point = source_map.start_point(after_crate_name);
1401 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1405 // In this case, `start_snippet` must equal '{'.
1406 format!("{}{}, ", start_snippet, import_snippet)
1408 // In this case, add a `{`, then the moved import, then whatever
1409 // was there before.
1410 format!("{{{}, {}", import_snippet, start_snippet)
1415 // Add a `};` to the end if nested, matching the `{` added at the start.
1417 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1421 let suggestion = Some((
1423 String::from("a macro with this name exists at the root of the crate"),
1424 Applicability::MaybeIncorrect,
1427 "this could be because a macro annotated with `#[macro_export]` will be exported \
1428 at the root of the crate instead of the module where it is defined"
1431 Some((suggestion, note))
1438 /// Given a `binding_span` of a binding within a use statement:
1441 /// use foo::{a, b, c};
1445 /// then return the span until the next binding or the end of the statement:
1448 /// use foo::{a, b, c};
1451 pub(crate) fn find_span_of_binding_until_next_binding(
1456 let source_map = sess.source_map();
1458 // Find the span of everything after the binding.
1459 // ie. `a, e};` or `a};`
1460 let binding_until_end = binding_span.with_hi(use_span.hi());
1462 // Find everything after the binding but not including the binding.
1463 // ie. `, e};` or `};`
1464 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1466 // Keep characters in the span until we encounter something that isn't a comma or
1470 // Also note whether a closing brace character was encountered. If there
1471 // was, then later go backwards to remove any trailing commas that are left.
1472 let mut found_closing_brace = false;
1473 let after_binding_until_next_binding =
1474 source_map.span_take_while(after_binding_until_end, |&ch| {
1476 found_closing_brace = true;
1478 ch == ' ' || ch == ','
1481 // Combine the two spans.
1482 // ie. `a, ` or `a`.
1484 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1485 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1487 (found_closing_brace, span)
1490 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1494 /// use foo::a::{a, b, c};
1495 /// ^^--- binding span
1499 /// use foo::{a, b, c};
1500 /// --- binding span
1502 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1503 let source_map = sess.source_map();
1505 // `prev_source` will contain all of the source that came before the span.
1506 // Then split based on a command and take the first (ie. closest to our span)
1507 // snippet. In the example, this is a space.
1508 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1510 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1511 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1512 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1516 let prev_comma = prev_comma.first().unwrap();
1517 let prev_starting_brace = prev_starting_brace.first().unwrap();
1519 // If the amount of source code before the comma is greater than
1520 // the amount of source code before the starting brace then we've only
1521 // got one item in the nested item (eg. `issue_52891::{self}`).
1522 if prev_comma.len() > prev_starting_brace.len() {
1526 Some(binding_span.with_lo(BytePos(
1527 // Take away the number of bytes for the characters we've found and an
1528 // extra for the comma.
1529 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1533 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1534 /// it is a nested use tree.
1537 /// use foo::a::{b, c};
1538 /// ^^^^^^^^^^ // false
1540 /// use foo::{a, b, c};
1541 /// ^^^^^^^^^^ // true
1543 /// use foo::{a, b::{c, d}};
1544 /// ^^^^^^^^^^^^^^^ // true
1546 fn find_span_immediately_after_crate_name(
1548 module_name: Symbol,
1552 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1553 module_name, use_span
1555 let source_map = sess.source_map();
1557 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1558 let mut num_colons = 0;
1559 // Find second colon.. `use issue_59764:`
1560 let until_second_colon = source_map.span_take_while(use_span, |c| {
1565 ':' if num_colons == 2 => false,
1569 // Find everything after the second colon.. `foo::{baz, makro};`
1570 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1572 let mut found_a_non_whitespace_character = false;
1573 // Find the first non-whitespace character in `from_second_colon`.. `f`
1574 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1575 if found_a_non_whitespace_character {
1578 if !c.is_whitespace() {
1579 found_a_non_whitespace_character = true;
1584 // Find the first `{` in from_second_colon.. `foo::{`
1585 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1587 (next_left_bracket == after_second_colon, from_second_colon)
1590 /// When an entity with a given name is not available in scope, we search for
1591 /// entities with that name in all crates. This method allows outputting the
1592 /// results of this search in a programmer-friendly way
1593 crate fn show_candidates(
1594 err: &mut DiagnosticBuilder<'_>,
1595 // This is `None` if all placement locations are inside expansions
1596 use_placement_span: Option<Span>,
1597 candidates: &[ImportSuggestion],
1601 if candidates.is_empty() {
1605 // we want consistent results across executions, but candidates are produced
1606 // by iterating through a hash map, so make sure they are ordered:
1607 let mut path_strings: Vec<_> =
1608 candidates.iter().map(|c| path_names_to_string(&c.path)).collect();
1610 path_strings.sort();
1611 path_strings.dedup();
1613 let (determiner, kind) = if candidates.len() == 1 {
1614 ("this", candidates[0].descr)
1616 ("one of these", "items")
1619 let instead = if instead { " instead" } else { "" };
1620 let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
1622 if let Some(span) = use_placement_span {
1623 for candidate in &mut path_strings {
1624 // produce an additional newline to separate the new use statement
1625 // from the directly following item.
1626 let additional_newline = if found_use { "" } else { "\n" };
1627 *candidate = format!("use {};\n{}", candidate, additional_newline);
1630 err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
1634 for candidate in path_strings {
1636 msg.push_str(&candidate);