5 use rustc::session::Session;
6 use rustc::ty::{self, DefIdTree};
7 use rustc_data_structures::fx::FxHashSet;
8 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
9 use rustc_feature::BUILTIN_ATTRIBUTES;
10 use rustc_hir::def::Namespace::{self, *};
11 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
12 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
13 use rustc_span::hygiene::MacroKind;
14 use rustc_span::source_map::SourceMap;
15 use rustc_span::symbol::{kw, Symbol};
16 use rustc_span::{BytePos, MultiSpan, Span};
17 use syntax::ast::{self, Ident, Path};
18 use syntax::print::pprust;
19 use syntax::util::lev_distance::find_best_match_for_name;
21 use crate::imports::{ImportDirective, ImportDirectiveSubclass, ImportResolver};
22 use crate::path_names_to_string;
23 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
24 use crate::{BindingError, CrateLint, HasGenericParams, LegacyScope, Module, ModuleOrUniformRoot};
25 use crate::{NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
26 use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment};
28 use rustc_error_codes::*;
30 type Res = def::Res<ast::NodeId>;
32 /// A vector of spans and replacements, a message and applicability.
33 crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
35 crate struct TypoSuggestion {
36 pub candidate: Symbol,
41 crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
42 TypoSuggestion { candidate, res }
46 /// A free importable items suggested in case of resolution failure.
47 crate struct ImportSuggestion {
48 pub did: Option<DefId>,
52 /// Adjust the impl span so that just the `impl` keyword is taken by removing
53 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
54 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
56 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
57 /// parser. If you need to use this function or something similar, please consider updating the
58 /// `source_map` functions and this function to something more robust.
59 fn reduce_impl_span_to_impl_keyword(cm: &SourceMap, impl_span: Span) -> Span {
60 let impl_span = cm.span_until_char(impl_span, '<');
61 let impl_span = cm.span_until_whitespace(impl_span);
65 impl<'a> Resolver<'a> {
66 crate fn add_module_candidates(
69 names: &mut Vec<TypoSuggestion>,
70 filter_fn: &impl Fn(Res) -> bool,
72 for (key, resolution) in self.resolutions(module).borrow().iter() {
73 if let Some(binding) = resolution.borrow().binding {
74 let res = binding.res();
76 names.push(TypoSuggestion::from_res(key.ident.name, res));
82 /// Combines an error with provided span and emits it.
84 /// This takes the error provided, combines it with the span and any additional spans inside the
85 /// error and emits it.
86 crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
87 self.into_struct_error(span, resolution_error).emit();
90 crate fn into_struct_error(
93 resolution_error: ResolutionError<'_>,
94 ) -> DiagnosticBuilder<'_> {
95 match resolution_error {
96 ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
97 let mut err = struct_span_err!(
101 "can't use generic parameters from outer function",
103 err.span_label(span, format!("use of generic parameter from outer function"));
105 let cm = self.session.source_map();
107 Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => {
108 if let Some(impl_span) =
109 maybe_impl_defid.and_then(|def_id| self.definitions.opt_span(def_id))
112 reduce_impl_span_to_impl_keyword(cm, impl_span),
113 "`Self` type implicitly declared here, by this `impl`",
116 match (maybe_trait_defid, maybe_impl_defid) {
118 err.span_label(span, "can't use `Self` here");
121 err.span_label(span, "use a type here instead");
123 (None, None) => bug!("`impl` without trait nor type?"),
127 Res::Def(DefKind::TyParam, def_id) => {
128 if let Some(span) = self.definitions.opt_span(def_id) {
129 err.span_label(span, "type parameter from outer function");
132 Res::Def(DefKind::ConstParam, def_id) => {
133 if let Some(span) = self.definitions.opt_span(def_id) {
134 err.span_label(span, "const parameter from outer function");
139 "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
145 if has_generic_params == HasGenericParams::Yes {
146 // Try to retrieve the span of the function signature and generate a new
147 // message with a local type or const parameter.
148 let sugg_msg = &format!("try using a local generic parameter instead");
149 if let Some((sugg_span, snippet)) = cm.generate_local_type_param_snippet(span) {
150 // Suggest the modification to the user
155 Applicability::MachineApplicable,
157 } else if let Some(sp) = cm.generate_fn_name_span(span) {
160 format!("try adding a local generic parameter in this method instead"),
163 err.help(&format!("try using a local generic parameter instead"));
169 ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
170 let mut err = struct_span_err!(
174 "the name `{}` is already used for a generic \
175 parameter in this item's generic parameters",
178 err.span_label(span, "already used");
179 err.span_label(first_use_span, format!("first use of `{}`", name));
182 ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
183 let mut err = struct_span_err!(
187 "method `{}` is not a member of trait `{}`",
191 err.span_label(span, format!("not a member of trait `{}`", trait_));
194 ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
195 let mut err = struct_span_err!(
199 "type `{}` is not a member of trait `{}`",
203 err.span_label(span, format!("not a member of trait `{}`", trait_));
206 ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
207 let mut err = struct_span_err!(
211 "const `{}` is not a member of trait `{}`",
215 err.span_label(span, format!("not a member of trait `{}`", trait_));
218 ResolutionError::VariableNotBoundInPattern(binding_error) => {
219 let BindingError { name, target, origin, could_be_path } = binding_error;
221 let target_sp = target.iter().copied().collect::<Vec<_>>();
222 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
224 let msp = MultiSpan::from_spans(target_sp.clone());
225 let mut err = struct_span_err!(
229 "variable `{}` is not bound in all patterns",
232 for sp in target_sp {
233 err.span_label(sp, format!("pattern doesn't bind `{}`", name));
235 for sp in origin_sp {
236 err.span_label(sp, "variable not in all patterns");
239 let help_msg = format!(
240 "if you meant to match on a variant or a `const` item, consider \
241 making the path in the pattern qualified: `?::{}`",
244 err.span_help(span, &help_msg);
248 ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
249 let mut err = struct_span_err!(
253 "variable `{}` is bound in inconsistent \
254 ways within the same match arm",
257 err.span_label(span, "bound in different ways");
258 err.span_label(first_binding_span, "first binding");
261 ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
262 let mut err = struct_span_err!(
266 "identifier `{}` is bound more than once in this parameter list",
269 err.span_label(span, "used as parameter more than once");
272 ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
273 let mut err = struct_span_err!(
277 "identifier `{}` is bound more than once in the same pattern",
280 err.span_label(span, "used in a pattern more than once");
283 ResolutionError::UndeclaredLabel(name, lev_candidate) => {
284 let mut err = struct_span_err!(
288 "use of undeclared label `{}`",
291 if let Some(lev_candidate) = lev_candidate {
294 "a label with a similar name exists in this scope",
295 lev_candidate.to_string(),
296 Applicability::MaybeIncorrect,
299 err.span_label(span, format!("undeclared label `{}`", name));
303 ResolutionError::SelfImportsOnlyAllowedWithin => struct_span_err!(
308 "`self` imports are only allowed within a { } list"
310 ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
311 let mut err = struct_span_err!(
315 "`self` import can only appear once in an import list"
317 err.span_label(span, "can only appear once in an import list");
320 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
321 let mut err = struct_span_err!(
325 "`self` import can only appear in an import list with \
328 err.span_label(span, "can only appear in an import list with a non-empty prefix");
331 ResolutionError::FailedToResolve { label, suggestion } => {
333 struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
334 err.span_label(span, label);
336 if let Some((suggestions, msg, applicability)) = suggestion {
337 err.multipart_suggestion(&msg, suggestions, applicability);
342 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
343 let mut err = struct_span_err!(
348 "can't capture dynamic environment in a fn item"
350 err.help("use the `|| { ... }` closure form instead");
353 ResolutionError::AttemptToUseNonConstantValueInConstant => {
354 let mut err = struct_span_err!(
358 "attempt to use a non-constant value in a constant"
360 err.span_label(span, "non-constant value");
363 ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
364 let res = binding.res();
365 let shadows_what = res.descr();
366 let mut err = struct_span_err!(
370 "{}s cannot shadow {}s",
376 format!("cannot be named the same as {} {}", res.article(), shadows_what),
378 let participle = if binding.is_import() { "imported" } else { "defined" };
379 let msg = format!("the {} `{}` is {} here", shadows_what, name, participle);
380 err.span_label(binding.span, msg);
383 ResolutionError::ForwardDeclaredTyParam => {
384 let mut err = struct_span_err!(
388 "type parameters with a default cannot use \
389 forward declared identifiers"
393 "defaulted type parameters cannot be forward declared".to_string(),
397 ResolutionError::SelfInTyParamDefault => {
398 let mut err = struct_span_err!(
402 "type parameters cannot use `Self` in their defaults"
404 err.span_label(span, "`Self` in type parameter default".to_string());
410 crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
411 match vis_resolution_error {
412 VisResolutionError::Relative2018(span, path) => {
413 let mut err = self.session.struct_span_err(
415 "relative paths are not supported in visibilities on 2018 edition",
420 format!("crate::{}", pprust::path_to_string(&path)),
421 Applicability::MaybeIncorrect,
425 VisResolutionError::AncestorOnly(span) => struct_span_err!(
429 "visibilities can only be restricted to ancestor modules"
431 VisResolutionError::FailedToResolve(span, label, suggestion) => {
432 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
434 VisResolutionError::ExpectedFound(span, path_str, res) => {
435 let mut err = struct_span_err!(
439 "expected module, found {} `{}`",
443 err.span_label(span, "not a module");
446 VisResolutionError::Indeterminate(span) => struct_span_err!(
450 "cannot determine resolution for the visibility"
452 VisResolutionError::ModuleOnly(span) => {
453 self.session.struct_span_err(span, "visibility must resolve to a module")
459 /// Lookup typo candidate in scope for a macro or import.
460 fn early_lookup_typo_candidate(
463 parent_scope: &ParentScope<'a>,
465 filter_fn: &impl Fn(Res) -> bool,
466 ) -> Option<TypoSuggestion> {
467 let mut suggestions = Vec::new();
468 self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
470 Scope::DeriveHelpers(expn_id) => {
471 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
478 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
482 Scope::DeriveHelpersCompat => {
483 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
485 for derive in parent_scope.derives {
486 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
487 if let Ok((Some(ext), _)) = this.resolve_macro_path(
489 Some(MacroKind::Derive),
497 .map(|name| TypoSuggestion::from_res(*name, res)),
503 Scope::MacroRules(legacy_scope) => {
504 if let LegacyScope::Binding(legacy_binding) = legacy_scope {
505 let res = legacy_binding.binding.res();
508 .push(TypoSuggestion::from_res(legacy_binding.ident.name, res))
512 Scope::CrateRoot => {
513 let root_ident = Ident::new(kw::PathRoot, ident.span);
514 let root_module = this.resolve_crate_root(root_ident);
515 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
517 Scope::Module(module) => {
518 this.add_module_candidates(module, &mut suggestions, filter_fn);
520 Scope::RegisteredAttrs => {
521 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
524 this.registered_attrs
526 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
530 Scope::MacroUsePrelude => {
531 suggestions.extend(this.macro_use_prelude.iter().filter_map(
533 let res = binding.res();
534 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
538 Scope::BuiltinAttrs => {
539 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
544 .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
548 Scope::ExternPrelude => {
549 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
550 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
551 filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
554 Scope::ToolPrelude => {
555 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
557 this.registered_tools
559 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
562 Scope::StdLibPrelude => {
563 if let Some(prelude) = this.prelude {
564 let mut tmp_suggestions = Vec::new();
565 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
569 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
573 Scope::BuiltinTypes => {
574 let primitive_types = &this.primitive_type_table.primitive_types;
575 suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| {
576 let res = Res::PrimTy(*prim_ty);
577 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
585 // Make sure error reporting is deterministic.
586 suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
588 match find_best_match_for_name(
589 suggestions.iter().map(|suggestion| &suggestion.candidate),
593 Some(found) if found != ident.name => {
594 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
600 fn lookup_import_candidates_from_module<FilterFn>(
603 namespace: Namespace,
604 start_module: Module<'a>,
607 ) -> Vec<ImportSuggestion>
609 FilterFn: Fn(Res) -> bool,
611 let mut candidates = Vec::new();
612 let mut seen_modules = FxHashSet::default();
613 let not_local_module = crate_name.name != kw::Crate;
614 let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), not_local_module)];
616 while let Some((in_module, path_segments, in_module_is_extern)) = worklist.pop() {
617 // We have to visit module children in deterministic order to avoid
618 // instabilities in reported imports (#43552).
619 in_module.for_each_child(self, |this, ident, ns, name_binding| {
620 // avoid imports entirely
621 if name_binding.is_import() && !name_binding.is_extern_crate() {
624 // avoid non-importable candidates as well
625 if !name_binding.is_importable() {
629 // collect results based on the filter function
630 if ident.name == lookup_ident.name && ns == namespace {
631 let res = name_binding.res();
634 let mut segms = path_segments.clone();
635 if lookup_ident.span.rust_2018() {
636 // crate-local absolute paths start with `crate::` in edition 2018
637 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
638 segms.insert(0, ast::PathSegment::from_ident(crate_name));
641 segms.push(ast::PathSegment::from_ident(ident));
642 let path = Path { span: name_binding.span, segments: segms };
643 // the entity is accessible in the following cases:
644 // 1. if it's defined in the same crate, it's always
645 // accessible (since private entities can be made public)
646 // 2. if it's defined in another crate, it's accessible
647 // only if both the module is public and the entity is
648 // declared as public (due to pruning, we don't explore
649 // outside crate private modules => no need to check this)
650 if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
651 let did = match res {
652 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
653 _ => res.opt_def_id(),
655 candidates.push(ImportSuggestion { did, path });
660 // collect submodules to explore
661 if let Some(module) = name_binding.module() {
663 let mut path_segments = path_segments.clone();
664 path_segments.push(ast::PathSegment::from_ident(ident));
666 let is_extern_crate_that_also_appears_in_prelude =
667 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
669 let is_visible_to_user =
670 !in_module_is_extern || name_binding.vis == ty::Visibility::Public;
672 if !is_extern_crate_that_also_appears_in_prelude && is_visible_to_user {
673 // add the module to the lookup
674 let is_extern = in_module_is_extern || name_binding.is_extern_crate();
675 if seen_modules.insert(module.def_id().unwrap()) {
676 worklist.push((module, path_segments, is_extern));
686 /// When name resolution fails, this method can be used to look up candidate
687 /// entities with the expected name. It allows filtering them using the
688 /// supplied predicate (which should be used to only accept the types of
689 /// definitions expected, e.g., traits). The lookup spans across all crates.
691 /// N.B., the method does not look into imports, but this is not a problem,
692 /// since we report the definitions (thus, the de-aliased imports).
693 crate fn lookup_import_candidates<FilterFn>(
696 namespace: Namespace,
698 ) -> Vec<ImportSuggestion>
700 FilterFn: Fn(Res) -> bool,
702 let mut suggestions = self.lookup_import_candidates_from_module(
706 Ident::with_dummy_span(kw::Crate),
710 if lookup_ident.span.rust_2018() {
711 let extern_prelude_names = self.extern_prelude.clone();
712 for (ident, _) in extern_prelude_names.into_iter() {
713 if ident.span.from_expansion() {
714 // Idents are adjusted to the root context before being
715 // resolved in the extern prelude, so reporting this to the
716 // user is no help. This skips the injected
717 // `extern crate std` in the 2018 edition, which would
718 // otherwise cause duplicate suggestions.
721 if let Some(crate_id) =
722 self.crate_loader.maybe_process_path_extern(ident.name, ident.span)
725 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
726 suggestions.extend(self.lookup_import_candidates_from_module(
740 crate fn unresolved_macro_suggestions(
742 err: &mut DiagnosticBuilder<'a>,
743 macro_kind: MacroKind,
744 parent_scope: &ParentScope<'a>,
747 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
748 let suggestion = self.early_lookup_typo_candidate(
749 ScopeSet::Macro(macro_kind),
754 self.add_typo_suggestion(err, suggestion, ident.span);
756 if macro_kind == MacroKind::Derive && (ident.as_str() == "Send" || ident.as_str() == "Sync")
758 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
759 err.span_note(ident.span, &msg);
761 if self.macro_names.contains(&ident.modern()) {
762 err.help("have you added the `#[macro_use]` on the module/import?");
766 crate fn add_typo_suggestion(
768 err: &mut DiagnosticBuilder<'_>,
769 suggestion: Option<TypoSuggestion>,
772 if let Some(suggestion) = suggestion {
774 "{} {} with a similar name exists",
775 suggestion.res.article(),
776 suggestion.res.descr()
781 suggestion.candidate.to_string(),
782 Applicability::MaybeIncorrect,
784 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
785 LOCAL_CRATE => self.definitions.opt_span(def_id),
789 .def_span(self.cstore().get_span_untracked(def_id, self.session)),
792 if let Some(span) = def_span {
796 "similarly named {} `{}` defined here",
797 suggestion.res.descr(),
798 suggestion.candidate.as_str(),
807 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
809 if b.span.is_dummy() {
810 let add_built_in = match b.res() {
811 // These already contain the "built-in" prefix or look bad with it.
812 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
815 let (built_in, from) = if from_prelude {
816 ("", " from prelude")
817 } else if b.is_extern_crate()
819 && self.session.opts.externs.get(&ident.as_str()).is_some()
821 ("", " passed with `--extern`")
822 } else if add_built_in {
828 let article = if built_in.is_empty() { res.article() } else { "a" };
830 "{a}{built_in} {thing}{from}",
837 let introduced = if b.is_import() { "imported" } else { "defined" };
838 format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced)
842 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
843 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
844 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
845 // We have to print the span-less alternative first, otherwise formatting looks bad.
846 (b2, b1, misc2, misc1, true)
848 (b1, b2, misc1, misc2, false)
851 let mut err = struct_span_err!(
855 "`{ident}` is ambiguous ({why})",
859 err.span_label(ident.span, "ambiguous name");
861 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
862 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
863 let note_msg = format!(
864 "`{ident}` could{also} refer to {what}",
870 let thing = b.res().descr();
871 let mut help_msgs = Vec::new();
872 if b.is_glob_import()
873 && (kind == AmbiguityKind::GlobVsGlob
874 || kind == AmbiguityKind::GlobVsExpanded
875 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
877 help_msgs.push(format!(
878 "consider adding an explicit import of \
879 `{ident}` to disambiguate",
883 if b.is_extern_crate() && ident.span.rust_2018() {
884 help_msgs.push(format!(
885 "use `::{ident}` to refer to this {thing} unambiguously",
890 if misc == AmbiguityErrorMisc::SuggestCrate {
891 help_msgs.push(format!(
892 "use `crate::{ident}` to refer to this {thing} unambiguously",
896 } else if misc == AmbiguityErrorMisc::SuggestSelf {
897 help_msgs.push(format!(
898 "use `self::{ident}` to refer to this {thing} unambiguously",
904 err.span_note(b.span, ¬e_msg);
905 for (i, help_msg) in help_msgs.iter().enumerate() {
906 let or = if i == 0 { "" } else { "or " };
907 err.help(&format!("{}{}", or, help_msg));
911 could_refer_to(b1, misc1, "");
912 could_refer_to(b2, misc2, " also");
916 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
917 let PrivacyError { ident, binding, .. } = *privacy_error;
918 let session = &self.session;
919 let mk_struct_span_error = |is_constructor| {
920 let mut descr = binding.res().descr().to_string();
922 descr += " constructor";
924 if binding.is_import() {
929 struct_span_err!(session, ident.span, E0603, "{} `{}` is private", descr, ident);
931 err.span_label(ident.span, &format!("this {} is private", descr));
933 session.source_map().def_span(binding.span),
934 &format!("the {} `{}` is defined here", descr, ident),
940 let mut err = if let NameBindingKind::Res(
941 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
945 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
946 if let Some(fields) = self.field_names.get(&def_id) {
947 let mut err = mk_struct_span_error(true);
948 let first_field = fields.first().expect("empty field list in the map");
950 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
951 "a constructor is private if any of the fields is private",
955 mk_struct_span_error(false)
958 mk_struct_span_error(false)
965 impl<'a, 'b> ImportResolver<'a, 'b> {
966 /// Adds suggestions for a path that cannot be resolved.
967 pub(crate) fn make_path_suggestion(
970 mut path: Vec<Segment>,
971 parent_scope: &ParentScope<'b>,
972 ) -> Option<(Vec<Segment>, Vec<String>)> {
973 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
975 match (path.get(0), path.get(1)) {
976 // `{{root}}::ident::...` on both editions.
977 // On 2015 `{{root}}` is usually added implicitly.
978 (Some(fst), Some(snd))
979 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
980 // `ident::...` on 2018.
982 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
984 // Insert a placeholder that's later replaced by `self`/`super`/etc.
985 path.insert(0, Segment::from_ident(Ident::invalid()));
990 self.make_missing_self_suggestion(span, path.clone(), parent_scope)
991 .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
992 .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
993 .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
996 /// Suggest a missing `self::` if that resolves to an correct module.
1000 /// LL | use foo::Bar;
1001 /// | ^^^ did you mean `self::foo`?
1003 fn make_missing_self_suggestion(
1006 mut path: Vec<Segment>,
1007 parent_scope: &ParentScope<'b>,
1008 ) -> Option<(Vec<Segment>, Vec<String>)> {
1009 // Replace first ident with `self` and check if that is valid.
1010 path[0].ident.name = kw::SelfLower;
1011 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1012 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1013 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1016 /// Suggests a missing `crate::` if that resolves to an correct module.
1020 /// LL | use foo::Bar;
1021 /// | ^^^ did you mean `crate::foo`?
1023 fn make_missing_crate_suggestion(
1026 mut path: Vec<Segment>,
1027 parent_scope: &ParentScope<'b>,
1028 ) -> Option<(Vec<Segment>, Vec<String>)> {
1029 // Replace first ident with `crate` and check if that is valid.
1030 path[0].ident.name = kw::Crate;
1031 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1032 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1033 if let PathResult::Module(..) = result {
1037 "`use` statements changed in Rust 2018; read more at \
1038 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1048 /// Suggests a missing `super::` if that resolves to an correct module.
1052 /// LL | use foo::Bar;
1053 /// | ^^^ did you mean `super::foo`?
1055 fn make_missing_super_suggestion(
1058 mut path: Vec<Segment>,
1059 parent_scope: &ParentScope<'b>,
1060 ) -> Option<(Vec<Segment>, Vec<String>)> {
1061 // Replace first ident with `crate` and check if that is valid.
1062 path[0].ident.name = kw::Super;
1063 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1064 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1065 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1068 /// Suggests a missing external crate name if that resolves to an correct module.
1072 /// LL | use foobar::Baz;
1073 /// | ^^^^^^ did you mean `baz::foobar`?
1076 /// Used when importing a submodule of an external crate but missing that crate's
1077 /// name as the first part of path.
1078 fn make_external_crate_suggestion(
1081 mut path: Vec<Segment>,
1082 parent_scope: &ParentScope<'b>,
1083 ) -> Option<(Vec<Segment>, Vec<String>)> {
1084 if path[1].ident.span.rust_2015() {
1088 // Sort extern crate names in reverse order to get
1089 // 1) some consistent ordering for emitted dignostics, and
1090 // 2) `std` suggestions before `core` suggestions.
1091 let mut extern_crate_names =
1092 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1093 extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
1095 for name in extern_crate_names.into_iter() {
1096 // Replace first ident with a crate name and check if that is valid.
1097 path[0].ident.name = name;
1098 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1100 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1103 if let PathResult::Module(..) = result {
1104 return Some((path, Vec::new()));
1111 /// Suggests importing a macro from the root of the crate rather than a module within
1115 /// help: a macro with this name exists at the root of the crate
1117 /// LL | use issue_59764::makro;
1118 /// | ^^^^^^^^^^^^^^^^^^
1120 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1121 /// at the root of the crate instead of the module where it is defined
1123 pub(crate) fn check_for_module_export_macro(
1125 directive: &'b ImportDirective<'b>,
1126 module: ModuleOrUniformRoot<'b>,
1128 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1129 let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
1135 while let Some(parent) = crate_module.parent {
1136 crate_module = parent;
1139 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1140 // Don't make a suggestion if the import was already from the root of the
1145 let resolutions = self.r.resolutions(crate_module).borrow();
1146 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1147 let binding = resolution.borrow().binding()?;
1148 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1149 let module_name = crate_module.kind.name().unwrap();
1150 let import = match directive.subclass {
1151 ImportDirectiveSubclass::SingleImport { source, target, .. }
1152 if source != target =>
1154 format!("{} as {}", source, target)
1156 _ => format!("{}", ident),
1159 let mut corrections: Vec<(Span, String)> = Vec::new();
1160 if !directive.is_nested() {
1161 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1162 // intermediate segments.
1163 corrections.push((directive.span, format!("{}::{}", module_name, import)));
1165 // Find the binding span (and any trailing commas and spaces).
1166 // ie. `use a::b::{c, d, e};`
1168 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1174 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1175 found_closing_brace, binding_span
1178 let mut removal_span = binding_span;
1179 if found_closing_brace {
1180 // If the binding span ended with a closing brace, as in the below example:
1181 // ie. `use a::b::{c, d};`
1183 // Then expand the span of characters to remove to include the previous
1184 // binding's trailing comma.
1185 // ie. `use a::b::{c, d};`
1187 if let Some(previous_span) =
1188 extend_span_to_previous_binding(self.r.session, binding_span)
1190 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1191 removal_span = removal_span.with_lo(previous_span.lo());
1194 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1196 // Remove the `removal_span`.
1197 corrections.push((removal_span, "".to_string()));
1199 // Find the span after the crate name and if it has nested imports immediatately
1200 // after the crate name already.
1201 // ie. `use a::b::{c, d};`
1203 // or `use a::{b, c, d}};`
1205 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1211 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1212 has_nested, after_crate_name
1215 let source_map = self.r.session.source_map();
1217 // Add the import to the start, with a `{` if required.
1218 let start_point = source_map.start_point(after_crate_name);
1219 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1223 // In this case, `start_snippet` must equal '{'.
1224 format!("{}{}, ", start_snippet, import)
1226 // In this case, add a `{`, then the moved import, then whatever
1227 // was there before.
1228 format!("{{{}, {}", import, start_snippet)
1233 // Add a `};` to the end if nested, matching the `{` added at the start.
1235 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1239 let suggestion = Some((
1241 String::from("a macro with this name exists at the root of the crate"),
1242 Applicability::MaybeIncorrect,
1245 "this could be because a macro annotated with `#[macro_export]` will be exported \
1246 at the root of the crate instead of the module where it is defined"
1249 Some((suggestion, note))
1256 /// Given a `binding_span` of a binding within a use statement:
1259 /// use foo::{a, b, c};
1263 /// then return the span until the next binding or the end of the statement:
1266 /// use foo::{a, b, c};
1269 pub(crate) fn find_span_of_binding_until_next_binding(
1274 let source_map = sess.source_map();
1276 // Find the span of everything after the binding.
1277 // ie. `a, e};` or `a};`
1278 let binding_until_end = binding_span.with_hi(use_span.hi());
1280 // Find everything after the binding but not including the binding.
1281 // ie. `, e};` or `};`
1282 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1284 // Keep characters in the span until we encounter something that isn't a comma or
1288 // Also note whether a closing brace character was encountered. If there
1289 // was, then later go backwards to remove any trailing commas that are left.
1290 let mut found_closing_brace = false;
1291 let after_binding_until_next_binding =
1292 source_map.span_take_while(after_binding_until_end, |&ch| {
1294 found_closing_brace = true;
1296 ch == ' ' || ch == ','
1299 // Combine the two spans.
1300 // ie. `a, ` or `a`.
1302 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1303 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1305 (found_closing_brace, span)
1308 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1312 /// use foo::a::{a, b, c};
1313 /// ^^--- binding span
1317 /// use foo::{a, b, c};
1318 /// --- binding span
1320 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1321 let source_map = sess.source_map();
1323 // `prev_source` will contain all of the source that came before the span.
1324 // Then split based on a command and take the first (ie. closest to our span)
1325 // snippet. In the example, this is a space.
1326 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1328 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1329 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1330 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1334 let prev_comma = prev_comma.first().unwrap();
1335 let prev_starting_brace = prev_starting_brace.first().unwrap();
1337 // If the amount of source code before the comma is greater than
1338 // the amount of source code before the starting brace then we've only
1339 // got one item in the nested item (eg. `issue_52891::{self}`).
1340 if prev_comma.len() > prev_starting_brace.len() {
1344 Some(binding_span.with_lo(BytePos(
1345 // Take away the number of bytes for the characters we've found and an
1346 // extra for the comma.
1347 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1351 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1352 /// it is a nested use tree.
1355 /// use foo::a::{b, c};
1356 /// ^^^^^^^^^^ // false
1358 /// use foo::{a, b, c};
1359 /// ^^^^^^^^^^ // true
1361 /// use foo::{a, b::{c, d}};
1362 /// ^^^^^^^^^^^^^^^ // true
1364 fn find_span_immediately_after_crate_name(
1366 module_name: Symbol,
1370 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1371 module_name, use_span
1373 let source_map = sess.source_map();
1375 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1376 let mut num_colons = 0;
1377 // Find second colon.. `use issue_59764:`
1378 let until_second_colon = source_map.span_take_while(use_span, |c| {
1383 ':' if num_colons == 2 => false,
1387 // Find everything after the second colon.. `foo::{baz, makro};`
1388 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1390 let mut found_a_non_whitespace_character = false;
1391 // Find the first non-whitespace character in `from_second_colon`.. `f`
1392 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1393 if found_a_non_whitespace_character {
1396 if !c.is_whitespace() {
1397 found_a_non_whitespace_character = true;
1402 // Find the first `{` in from_second_colon.. `foo::{`
1403 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1405 (next_left_bracket == after_second_colon, from_second_colon)
1408 /// When an entity with a given name is not available in scope, we search for
1409 /// entities with that name in all crates. This method allows outputting the
1410 /// results of this search in a programmer-friendly way
1411 crate fn show_candidates(
1412 err: &mut DiagnosticBuilder<'_>,
1413 // This is `None` if all placement locations are inside expansions
1415 candidates: &[ImportSuggestion],
1419 // we want consistent results across executions, but candidates are produced
1420 // by iterating through a hash map, so make sure they are ordered:
1421 let mut path_strings: Vec<_> =
1422 candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
1423 path_strings.sort();
1425 let better = if better { "better " } else { "" };
1426 let msg_diff = match path_strings.len() {
1427 1 => " is found in another module, you can import it",
1428 _ => "s are found in other modules, you can import them",
1430 let msg = format!("possible {}candidate{} into scope", better, msg_diff);
1432 if let Some(span) = span {
1433 for candidate in &mut path_strings {
1434 // produce an additional newline to separate the new use statement
1435 // from the directly following item.
1436 let additional_newline = if found_use { "" } else { "\n" };
1437 *candidate = format!("use {};\n{}", candidate, additional_newline);
1440 err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
1444 for candidate in path_strings {
1446 msg.push_str(&candidate);