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::ParamInNonTrivialAnonConst(name) => {
470 let mut err = self.session.struct_span_err(
472 "generic parameters must not be used inside of non trivial constant values",
477 "non-trivial anonymous constants must not depend on the parameter `{}`",
482 &format!("it is currently only allowed to use either `{0}` or `{{ {0} }}` as generic constants", name)
486 ResolutionError::SelfInTyParamDefault => {
487 let mut err = struct_span_err!(
491 "type parameters cannot use `Self` in their defaults"
493 err.span_label(span, "`Self` in type parameter default".to_string());
496 ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
497 let mut err = struct_span_err!(
501 "use of unreachable label `{}`",
505 err.span_label(definition_span, "unreachable label defined here");
506 err.span_label(span, format!("unreachable label `{}`", name));
508 "labels are unreachable through functions, closures, async blocks and modules",
512 // A reachable label with a similar name exists.
513 Some((ident, true)) => {
514 err.span_label(ident.span, "a label with a similar name is reachable");
517 "try using similarly named label",
518 ident.name.to_string(),
519 Applicability::MaybeIncorrect,
522 // An unreachable label with a similar name exists.
523 Some((ident, false)) => {
526 "a label with a similar name exists but is also unreachable",
529 // No similarly-named labels exist.
538 crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
539 match vis_resolution_error {
540 VisResolutionError::Relative2018(span, path) => {
541 let mut err = self.session.struct_span_err(
543 "relative paths are not supported in visibilities on 2018 edition",
548 format!("crate::{}", pprust::path_to_string(&path)),
549 Applicability::MaybeIncorrect,
553 VisResolutionError::AncestorOnly(span) => struct_span_err!(
557 "visibilities can only be restricted to ancestor modules"
559 VisResolutionError::FailedToResolve(span, label, suggestion) => {
560 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
562 VisResolutionError::ExpectedFound(span, path_str, res) => {
563 let mut err = struct_span_err!(
567 "expected module, found {} `{}`",
571 err.span_label(span, "not a module");
574 VisResolutionError::Indeterminate(span) => struct_span_err!(
578 "cannot determine resolution for the visibility"
580 VisResolutionError::ModuleOnly(span) => {
581 self.session.struct_span_err(span, "visibility must resolve to a module")
587 /// Lookup typo candidate in scope for a macro or import.
588 fn early_lookup_typo_candidate(
591 parent_scope: &ParentScope<'a>,
593 filter_fn: &impl Fn(Res) -> bool,
594 ) -> Option<TypoSuggestion> {
595 let mut suggestions = Vec::new();
596 self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
598 Scope::DeriveHelpers(expn_id) => {
599 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
606 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
610 Scope::DeriveHelpersCompat => {
611 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
613 for derive in parent_scope.derives {
614 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
615 if let Ok((Some(ext), _)) = this.resolve_macro_path(
617 Some(MacroKind::Derive),
625 .map(|name| TypoSuggestion::from_res(*name, res)),
631 Scope::MacroRules(macro_rules_scope) => {
632 if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope {
633 let res = macro_rules_binding.binding.res();
636 .push(TypoSuggestion::from_res(macro_rules_binding.ident.name, res))
640 Scope::CrateRoot => {
641 let root_ident = Ident::new(kw::PathRoot, ident.span);
642 let root_module = this.resolve_crate_root(root_ident);
643 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
645 Scope::Module(module) => {
646 this.add_module_candidates(module, &mut suggestions, filter_fn);
648 Scope::RegisteredAttrs => {
649 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
652 this.registered_attrs
654 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
658 Scope::MacroUsePrelude => {
659 suggestions.extend(this.macro_use_prelude.iter().filter_map(
661 let res = binding.res();
662 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
666 Scope::BuiltinAttrs => {
667 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
672 .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
676 Scope::ExternPrelude => {
677 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
678 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
679 filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
682 Scope::ToolPrelude => {
683 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
685 this.registered_tools
687 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
690 Scope::StdLibPrelude => {
691 if let Some(prelude) = this.prelude {
692 let mut tmp_suggestions = Vec::new();
693 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
697 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
701 Scope::BuiltinTypes => {
702 let primitive_types = &this.primitive_type_table.primitive_types;
703 suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| {
704 let res = Res::PrimTy(*prim_ty);
705 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
713 // Make sure error reporting is deterministic.
714 suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
716 match find_best_match_for_name(
717 suggestions.iter().map(|suggestion| &suggestion.candidate),
721 Some(found) if found != ident.name => {
722 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
728 fn lookup_import_candidates_from_module<FilterFn>(
731 namespace: Namespace,
732 parent_scope: &ParentScope<'a>,
733 start_module: Module<'a>,
736 ) -> Vec<ImportSuggestion>
738 FilterFn: Fn(Res) -> bool,
740 let mut candidates = Vec::new();
741 let mut seen_modules = FxHashSet::default();
742 let not_local_module = crate_name.name != kw::Crate;
744 vec![(start_module, Vec::<ast::PathSegment>::new(), true, not_local_module)];
745 let mut worklist_via_import = vec![];
747 while let Some((in_module, path_segments, accessible, in_module_is_extern)) =
748 match worklist.pop() {
749 None => worklist_via_import.pop(),
753 // We have to visit module children in deterministic order to avoid
754 // instabilities in reported imports (#43552).
755 in_module.for_each_child(self, |this, ident, ns, name_binding| {
756 // avoid non-importable candidates
757 if !name_binding.is_importable() {
761 let child_accessible =
762 accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
764 // do not venture inside inaccessible items of other crates
765 if in_module_is_extern && !child_accessible {
769 let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
771 // There is an assumption elsewhere that paths of variants are in the enum's
772 // declaration and not imported. With this assumption, the variant component is
773 // chopped and the rest of the path is assumed to be the enum's own path. For
774 // errors where a variant is used as the type instead of the enum, this causes
775 // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
776 if via_import && name_binding.is_possibly_imported_variant() {
780 // collect results based on the filter function
781 // avoid suggesting anything from the same module in which we are resolving
782 if ident.name == lookup_ident.name
784 && !ptr::eq(in_module, parent_scope.module)
786 let res = name_binding.res();
789 let mut segms = path_segments.clone();
790 if lookup_ident.span.rust_2018() {
791 // crate-local absolute paths start with `crate::` in edition 2018
792 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
793 segms.insert(0, ast::PathSegment::from_ident(crate_name));
796 segms.push(ast::PathSegment::from_ident(ident));
797 let path = Path { span: name_binding.span, segments: segms };
798 let did = match res {
799 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
800 _ => res.opt_def_id(),
803 if child_accessible {
804 // Remove invisible match if exists
805 if let Some(idx) = candidates
807 .position(|v: &ImportSuggestion| v.did == did && !v.accessible)
809 candidates.remove(idx);
813 if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
814 candidates.push(ImportSuggestion {
818 accessible: child_accessible,
824 // collect submodules to explore
825 if let Some(module) = name_binding.module() {
827 let mut path_segments = path_segments.clone();
828 path_segments.push(ast::PathSegment::from_ident(ident));
830 let is_extern_crate_that_also_appears_in_prelude =
831 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
833 if !is_extern_crate_that_also_appears_in_prelude {
834 let is_extern = in_module_is_extern || name_binding.is_extern_crate();
835 // add the module to the lookup
836 if seen_modules.insert(module.def_id().unwrap()) {
837 if via_import { &mut worklist_via_import } else { &mut worklist }
838 .push((module, path_segments, child_accessible, is_extern));
845 // If only some candidates are accessible, take just them
846 if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
847 candidates = candidates.into_iter().filter(|x| x.accessible).collect();
853 /// When name resolution fails, this method can be used to look up candidate
854 /// entities with the expected name. It allows filtering them using the
855 /// supplied predicate (which should be used to only accept the types of
856 /// definitions expected, e.g., traits). The lookup spans across all crates.
858 /// N.B., the method does not look into imports, but this is not a problem,
859 /// since we report the definitions (thus, the de-aliased imports).
860 crate fn lookup_import_candidates<FilterFn>(
863 namespace: Namespace,
864 parent_scope: &ParentScope<'a>,
866 ) -> Vec<ImportSuggestion>
868 FilterFn: Fn(Res) -> bool,
870 let mut suggestions = self.lookup_import_candidates_from_module(
875 Ident::with_dummy_span(kw::Crate),
879 if lookup_ident.span.rust_2018() {
880 let extern_prelude_names = self.extern_prelude.clone();
881 for (ident, _) in extern_prelude_names.into_iter() {
882 if ident.span.from_expansion() {
883 // Idents are adjusted to the root context before being
884 // resolved in the extern prelude, so reporting this to the
885 // user is no help. This skips the injected
886 // `extern crate std` in the 2018 edition, which would
887 // otherwise cause duplicate suggestions.
890 if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
892 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
893 suggestions.extend(self.lookup_import_candidates_from_module(
908 crate fn unresolved_macro_suggestions(
910 err: &mut DiagnosticBuilder<'a>,
911 macro_kind: MacroKind,
912 parent_scope: &ParentScope<'a>,
915 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
916 let suggestion = self.early_lookup_typo_candidate(
917 ScopeSet::Macro(macro_kind),
922 self.add_typo_suggestion(err, suggestion, ident.span);
924 if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
925 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
926 err.span_note(ident.span, &msg);
928 if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
929 err.help("have you added the `#[macro_use]` on the module/import?");
933 crate fn add_typo_suggestion(
935 err: &mut DiagnosticBuilder<'_>,
936 suggestion: Option<TypoSuggestion>,
939 let suggestion = match suggestion {
940 None => return false,
941 // We shouldn't suggest underscore.
942 Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
943 Some(suggestion) => suggestion,
945 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
946 LOCAL_CRATE => self.opt_span(def_id),
950 .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
953 if let Some(def_span) = def_span {
954 if span.overlaps(def_span) {
955 // Don't suggest typo suggestion for itself like in the followoing:
956 // error[E0423]: expected function, tuple struct or tuple variant, found struct `X`
957 // --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14
960 // | ----------- `X` defined here
962 // LL | const Y: X = X("ö");
963 // | -------------^^^^^^- similarly named constant `Y` defined here
965 // help: use struct literal syntax instead
967 // LL | const Y: X = X {};
969 // help: a constant with a similar name exists
971 // LL | const Y: X = Y("ö");
976 self.session.source_map().guess_head_span(def_span),
978 "similarly named {} `{}` defined here",
979 suggestion.res.descr(),
980 suggestion.candidate.as_str(),
985 "{} {} with a similar name exists",
986 suggestion.res.article(),
987 suggestion.res.descr()
992 suggestion.candidate.to_string(),
993 Applicability::MaybeIncorrect,
998 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
1000 if b.span.is_dummy() {
1001 let add_built_in = match b.res() {
1002 // These already contain the "built-in" prefix or look bad with it.
1003 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
1006 let (built_in, from) = if from_prelude {
1007 ("", " from prelude")
1008 } else if b.is_extern_crate()
1010 && self.session.opts.externs.get(&ident.as_str()).is_some()
1012 ("", " passed with `--extern`")
1013 } else if add_built_in {
1019 let article = if built_in.is_empty() { res.article() } else { "a" };
1021 "{a}{built_in} {thing}{from}",
1023 thing = res.descr(),
1024 built_in = built_in,
1028 let introduced = if b.is_import() { "imported" } else { "defined" };
1029 format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced)
1033 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
1034 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
1035 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
1036 // We have to print the span-less alternative first, otherwise formatting looks bad.
1037 (b2, b1, misc2, misc1, true)
1039 (b1, b2, misc1, misc2, false)
1042 let mut err = struct_span_err!(
1046 "`{ident}` is ambiguous ({why})",
1050 err.span_label(ident.span, "ambiguous name");
1052 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
1053 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
1054 let note_msg = format!(
1055 "`{ident}` could{also} refer to {what}",
1061 let thing = b.res().descr();
1062 let mut help_msgs = Vec::new();
1063 if b.is_glob_import()
1064 && (kind == AmbiguityKind::GlobVsGlob
1065 || kind == AmbiguityKind::GlobVsExpanded
1066 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
1068 help_msgs.push(format!(
1069 "consider adding an explicit import of \
1070 `{ident}` to disambiguate",
1074 if b.is_extern_crate() && ident.span.rust_2018() {
1075 help_msgs.push(format!(
1076 "use `::{ident}` to refer to this {thing} unambiguously",
1081 if misc == AmbiguityErrorMisc::SuggestCrate {
1082 help_msgs.push(format!(
1083 "use `crate::{ident}` to refer to this {thing} unambiguously",
1087 } else if misc == AmbiguityErrorMisc::SuggestSelf {
1088 help_msgs.push(format!(
1089 "use `self::{ident}` to refer to this {thing} unambiguously",
1095 err.span_note(b.span, ¬e_msg);
1096 for (i, help_msg) in help_msgs.iter().enumerate() {
1097 let or = if i == 0 { "" } else { "or " };
1098 err.help(&format!("{}{}", or, help_msg));
1102 could_refer_to(b1, misc1, "");
1103 could_refer_to(b2, misc2, " also");
1107 /// If the binding refers to a tuple struct constructor with fields,
1108 /// returns the span of its fields.
1109 fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option<Span> {
1110 if let NameBindingKind::Res(
1111 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
1115 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
1116 let fields = self.field_names.get(&def_id)?;
1117 let first_field = fields.first()?; // Handle `struct Foo()`
1118 return Some(fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)));
1123 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
1124 let PrivacyError { ident, binding, .. } = *privacy_error;
1126 let res = binding.res();
1127 let ctor_fields_span = self.ctor_fields_span(binding);
1128 let plain_descr = res.descr().to_string();
1129 let nonimport_descr =
1130 if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
1131 let import_descr = nonimport_descr.clone() + " import";
1133 |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
1135 // Print the primary message.
1136 let descr = get_descr(binding);
1138 struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident);
1139 err.span_label(ident.span, &format!("private {}", descr));
1140 if let Some(span) = ctor_fields_span {
1141 err.span_label(span, "a constructor is private if any of the fields is private");
1144 // Print the whole import chain to make it easier to see what happens.
1145 let first_binding = binding;
1146 let mut next_binding = Some(binding);
1147 let mut next_ident = ident;
1148 while let Some(binding) = next_binding {
1149 let name = next_ident;
1150 next_binding = match binding.kind {
1151 _ if res == Res::Err => None,
1152 NameBindingKind::Import { binding, import, .. } => match import.kind {
1153 _ if binding.span.is_dummy() => None,
1154 ImportKind::Single { source, .. } => {
1155 next_ident = source;
1158 ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding),
1159 ImportKind::ExternCrate { .. } => None,
1164 let first = ptr::eq(binding, first_binding);
1165 let descr = get_descr(binding);
1167 "{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
1168 and_refers_to = if first { "" } else { "...and refers to " },
1171 which = if first { "" } else { " which" },
1172 dots = if next_binding.is_some() { "..." } else { "" },
1174 let def_span = self.session.source_map().guess_head_span(binding.span);
1175 let mut note_span = MultiSpan::from_span(def_span);
1176 if !first && binding.vis == ty::Visibility::Public {
1177 note_span.push_span_label(def_span, "consider importing it directly".into());
1179 err.span_note(note_span, &msg);
1186 impl<'a, 'b> ImportResolver<'a, 'b> {
1187 /// Adds suggestions for a path that cannot be resolved.
1188 pub(crate) fn make_path_suggestion(
1191 mut path: Vec<Segment>,
1192 parent_scope: &ParentScope<'b>,
1193 ) -> Option<(Vec<Segment>, Vec<String>)> {
1194 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
1196 match (path.get(0), path.get(1)) {
1197 // `{{root}}::ident::...` on both editions.
1198 // On 2015 `{{root}}` is usually added implicitly.
1199 (Some(fst), Some(snd))
1200 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
1201 // `ident::...` on 2018.
1203 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
1205 // Insert a placeholder that's later replaced by `self`/`super`/etc.
1206 path.insert(0, Segment::from_ident(Ident::invalid()));
1211 self.make_missing_self_suggestion(span, path.clone(), parent_scope)
1212 .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
1213 .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
1214 .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
1217 /// Suggest a missing `self::` if that resolves to an correct module.
1221 /// LL | use foo::Bar;
1222 /// | ^^^ did you mean `self::foo`?
1224 fn make_missing_self_suggestion(
1227 mut path: Vec<Segment>,
1228 parent_scope: &ParentScope<'b>,
1229 ) -> Option<(Vec<Segment>, Vec<String>)> {
1230 // Replace first ident with `self` and check if that is valid.
1231 path[0].ident.name = kw::SelfLower;
1232 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1233 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1234 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1237 /// Suggests a missing `crate::` if that resolves to an correct module.
1241 /// LL | use foo::Bar;
1242 /// | ^^^ did you mean `crate::foo`?
1244 fn make_missing_crate_suggestion(
1247 mut path: Vec<Segment>,
1248 parent_scope: &ParentScope<'b>,
1249 ) -> Option<(Vec<Segment>, Vec<String>)> {
1250 // Replace first ident with `crate` and check if that is valid.
1251 path[0].ident.name = kw::Crate;
1252 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1253 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1254 if let PathResult::Module(..) = result {
1258 "`use` statements changed in Rust 2018; read more at \
1259 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1269 /// Suggests a missing `super::` if that resolves to an correct module.
1273 /// LL | use foo::Bar;
1274 /// | ^^^ did you mean `super::foo`?
1276 fn make_missing_super_suggestion(
1279 mut path: Vec<Segment>,
1280 parent_scope: &ParentScope<'b>,
1281 ) -> Option<(Vec<Segment>, Vec<String>)> {
1282 // Replace first ident with `crate` and check if that is valid.
1283 path[0].ident.name = kw::Super;
1284 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1285 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1286 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1289 /// Suggests a missing external crate name if that resolves to an correct module.
1293 /// LL | use foobar::Baz;
1294 /// | ^^^^^^ did you mean `baz::foobar`?
1297 /// Used when importing a submodule of an external crate but missing that crate's
1298 /// name as the first part of path.
1299 fn make_external_crate_suggestion(
1302 mut path: Vec<Segment>,
1303 parent_scope: &ParentScope<'b>,
1304 ) -> Option<(Vec<Segment>, Vec<String>)> {
1305 if path[1].ident.span.rust_2015() {
1309 // Sort extern crate names in reverse order to get
1310 // 1) some consistent ordering for emitted diagnostics, and
1311 // 2) `std` suggestions before `core` suggestions.
1312 let mut extern_crate_names =
1313 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1314 extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
1316 for name in extern_crate_names.into_iter() {
1317 // Replace first ident with a crate name and check if that is valid.
1318 path[0].ident.name = name;
1319 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1321 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1324 if let PathResult::Module(..) = result {
1325 return Some((path, Vec::new()));
1332 /// Suggests importing a macro from the root of the crate rather than a module within
1336 /// help: a macro with this name exists at the root of the crate
1338 /// LL | use issue_59764::makro;
1339 /// | ^^^^^^^^^^^^^^^^^^
1341 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1342 /// at the root of the crate instead of the module where it is defined
1344 pub(crate) fn check_for_module_export_macro(
1346 import: &'b Import<'b>,
1347 module: ModuleOrUniformRoot<'b>,
1349 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1350 let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
1356 while let Some(parent) = crate_module.parent {
1357 crate_module = parent;
1360 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1361 // Don't make a suggestion if the import was already from the root of the
1366 let resolutions = self.r.resolutions(crate_module).borrow();
1367 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1368 let binding = resolution.borrow().binding()?;
1369 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1370 let module_name = crate_module.kind.name().unwrap();
1371 let import_snippet = match import.kind {
1372 ImportKind::Single { source, target, .. } if source != target => {
1373 format!("{} as {}", source, target)
1375 _ => format!("{}", ident),
1378 let mut corrections: Vec<(Span, String)> = Vec::new();
1379 if !import.is_nested() {
1380 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1381 // intermediate segments.
1382 corrections.push((import.span, format!("{}::{}", module_name, import_snippet)));
1384 // Find the binding span (and any trailing commas and spaces).
1385 // ie. `use a::b::{c, d, e};`
1387 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1393 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1394 found_closing_brace, binding_span
1397 let mut removal_span = binding_span;
1398 if found_closing_brace {
1399 // If the binding span ended with a closing brace, as in the below example:
1400 // ie. `use a::b::{c, d};`
1402 // Then expand the span of characters to remove to include the previous
1403 // binding's trailing comma.
1404 // ie. `use a::b::{c, d};`
1406 if let Some(previous_span) =
1407 extend_span_to_previous_binding(self.r.session, binding_span)
1409 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1410 removal_span = removal_span.with_lo(previous_span.lo());
1413 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1415 // Remove the `removal_span`.
1416 corrections.push((removal_span, "".to_string()));
1418 // Find the span after the crate name and if it has nested imports immediatately
1419 // after the crate name already.
1420 // ie. `use a::b::{c, d};`
1422 // or `use a::{b, c, d}};`
1424 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1430 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1431 has_nested, after_crate_name
1434 let source_map = self.r.session.source_map();
1436 // Add the import to the start, with a `{` if required.
1437 let start_point = source_map.start_point(after_crate_name);
1438 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1442 // In this case, `start_snippet` must equal '{'.
1443 format!("{}{}, ", start_snippet, import_snippet)
1445 // In this case, add a `{`, then the moved import, then whatever
1446 // was there before.
1447 format!("{{{}, {}", import_snippet, start_snippet)
1452 // Add a `};` to the end if nested, matching the `{` added at the start.
1454 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1458 let suggestion = Some((
1460 String::from("a macro with this name exists at the root of the crate"),
1461 Applicability::MaybeIncorrect,
1464 "this could be because a macro annotated with `#[macro_export]` will be exported \
1465 at the root of the crate instead of the module where it is defined"
1468 Some((suggestion, note))
1475 /// Given a `binding_span` of a binding within a use statement:
1478 /// use foo::{a, b, c};
1482 /// then return the span until the next binding or the end of the statement:
1485 /// use foo::{a, b, c};
1488 pub(crate) fn find_span_of_binding_until_next_binding(
1493 let source_map = sess.source_map();
1495 // Find the span of everything after the binding.
1496 // ie. `a, e};` or `a};`
1497 let binding_until_end = binding_span.with_hi(use_span.hi());
1499 // Find everything after the binding but not including the binding.
1500 // ie. `, e};` or `};`
1501 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1503 // Keep characters in the span until we encounter something that isn't a comma or
1507 // Also note whether a closing brace character was encountered. If there
1508 // was, then later go backwards to remove any trailing commas that are left.
1509 let mut found_closing_brace = false;
1510 let after_binding_until_next_binding =
1511 source_map.span_take_while(after_binding_until_end, |&ch| {
1513 found_closing_brace = true;
1515 ch == ' ' || ch == ','
1518 // Combine the two spans.
1519 // ie. `a, ` or `a`.
1521 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1522 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1524 (found_closing_brace, span)
1527 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1531 /// use foo::a::{a, b, c};
1532 /// ^^--- binding span
1536 /// use foo::{a, b, c};
1537 /// --- binding span
1539 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1540 let source_map = sess.source_map();
1542 // `prev_source` will contain all of the source that came before the span.
1543 // Then split based on a command and take the first (ie. closest to our span)
1544 // snippet. In the example, this is a space.
1545 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1547 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1548 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1549 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1553 let prev_comma = prev_comma.first().unwrap();
1554 let prev_starting_brace = prev_starting_brace.first().unwrap();
1556 // If the amount of source code before the comma is greater than
1557 // the amount of source code before the starting brace then we've only
1558 // got one item in the nested item (eg. `issue_52891::{self}`).
1559 if prev_comma.len() > prev_starting_brace.len() {
1563 Some(binding_span.with_lo(BytePos(
1564 // Take away the number of bytes for the characters we've found and an
1565 // extra for the comma.
1566 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1570 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1571 /// it is a nested use tree.
1574 /// use foo::a::{b, c};
1575 /// ^^^^^^^^^^ // false
1577 /// use foo::{a, b, c};
1578 /// ^^^^^^^^^^ // true
1580 /// use foo::{a, b::{c, d}};
1581 /// ^^^^^^^^^^^^^^^ // true
1583 fn find_span_immediately_after_crate_name(
1585 module_name: Symbol,
1589 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1590 module_name, use_span
1592 let source_map = sess.source_map();
1594 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1595 let mut num_colons = 0;
1596 // Find second colon.. `use issue_59764:`
1597 let until_second_colon = source_map.span_take_while(use_span, |c| {
1602 ':' if num_colons == 2 => false,
1606 // Find everything after the second colon.. `foo::{baz, makro};`
1607 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1609 let mut found_a_non_whitespace_character = false;
1610 // Find the first non-whitespace character in `from_second_colon`.. `f`
1611 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1612 if found_a_non_whitespace_character {
1615 if !c.is_whitespace() {
1616 found_a_non_whitespace_character = true;
1621 // Find the first `{` in from_second_colon.. `foo::{`
1622 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1624 (next_left_bracket == after_second_colon, from_second_colon)
1627 /// When an entity with a given name is not available in scope, we search for
1628 /// entities with that name in all crates. This method allows outputting the
1629 /// results of this search in a programmer-friendly way
1630 crate fn show_candidates(
1631 err: &mut DiagnosticBuilder<'_>,
1632 // This is `None` if all placement locations are inside expansions
1633 use_placement_span: Option<Span>,
1634 candidates: &[ImportSuggestion],
1638 if candidates.is_empty() {
1642 // we want consistent results across executions, but candidates are produced
1643 // by iterating through a hash map, so make sure they are ordered:
1644 let mut path_strings: Vec<_> =
1645 candidates.iter().map(|c| path_names_to_string(&c.path)).collect();
1647 path_strings.sort();
1648 path_strings.dedup();
1650 let (determiner, kind) = if candidates.len() == 1 {
1651 ("this", candidates[0].descr)
1653 ("one of these", "items")
1656 let instead = if instead { " instead" } else { "" };
1657 let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
1659 if let Some(span) = use_placement_span {
1660 for candidate in &mut path_strings {
1661 // produce an additional newline to separate the new use statement
1662 // from the directly following item.
1663 let additional_newline = if found_use { "" } else { "\n" };
1664 *candidate = format!("use {};\n{}", candidate, additional_newline);
1667 err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
1671 for candidate in path_strings {
1673 msg.push_str(&candidate);