5 use rustc::session::Session;
6 use rustc::ty::{self, DefIdTree};
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_span::hygiene::MacroKind;
15 use rustc_span::source_map::SourceMap;
16 use rustc_span::symbol::{kw, Symbol};
17 use rustc_span::{BytePos, MultiSpan, Span};
18 use syntax::ast::{self, Ident, Path};
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 type Res = def::Res<ast::NodeId>;
30 /// A vector of spans and replacements, a message and applicability.
31 crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
33 crate struct TypoSuggestion {
34 pub candidate: Symbol,
39 crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
40 TypoSuggestion { candidate, res }
44 /// A free importable items suggested in case of resolution failure.
45 crate struct ImportSuggestion {
46 pub did: Option<DefId>,
50 /// Adjust the impl span so that just the `impl` keyword is taken by removing
51 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
52 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
54 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
55 /// parser. If you need to use this function or something similar, please consider updating the
56 /// `source_map` functions and this function to something more robust.
57 fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
58 let impl_span = sm.span_until_char(impl_span, '<');
59 let impl_span = sm.span_until_whitespace(impl_span);
63 impl<'a> Resolver<'a> {
64 crate fn add_module_candidates(
67 names: &mut Vec<TypoSuggestion>,
68 filter_fn: &impl Fn(Res) -> bool,
70 for (key, resolution) in self.resolutions(module).borrow().iter() {
71 if let Some(binding) = resolution.borrow().binding {
72 let res = binding.res();
74 names.push(TypoSuggestion::from_res(key.ident.name, res));
80 /// Combines an error with provided span and emits it.
82 /// This takes the error provided, combines it with the span and any additional spans inside the
83 /// error and emits it.
84 crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
85 self.into_struct_error(span, resolution_error).emit();
88 crate fn into_struct_error(
91 resolution_error: ResolutionError<'_>,
92 ) -> DiagnosticBuilder<'_> {
93 match resolution_error {
94 ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
95 let mut err = struct_span_err!(
99 "can't use generic parameters from outer function",
101 err.span_label(span, format!("use of generic parameter from outer function"));
103 let sm = self.session.source_map();
105 Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => {
106 if let Some(impl_span) =
107 maybe_impl_defid.and_then(|def_id| self.definitions.opt_span(def_id))
110 reduce_impl_span_to_impl_keyword(sm, impl_span),
111 "`Self` type implicitly declared here, by this `impl`",
114 match (maybe_trait_defid, maybe_impl_defid) {
116 err.span_label(span, "can't use `Self` here");
119 err.span_label(span, "use a type here instead");
121 (None, None) => bug!("`impl` without trait nor type?"),
125 Res::Def(DefKind::TyParam, def_id) => {
126 if let Some(span) = self.definitions.opt_span(def_id) {
127 err.span_label(span, "type parameter from outer function");
130 Res::Def(DefKind::ConstParam, def_id) => {
131 if let Some(span) = self.definitions.opt_span(def_id) {
132 err.span_label(span, "const parameter from outer function");
137 "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
143 if has_generic_params == HasGenericParams::Yes {
144 // Try to retrieve the span of the function signature and generate a new
145 // message with a local type or const parameter.
146 let sugg_msg = &format!("try using a local generic parameter instead");
147 if let Some((sugg_span, snippet)) = sm.generate_local_type_param_snippet(span) {
148 // Suggest the modification to the user
153 Applicability::MachineApplicable,
155 } else if let Some(sp) = sm.generate_fn_name_span(span) {
158 format!("try adding a local generic parameter in this method instead"),
161 err.help(&format!("try using a local generic parameter instead"));
167 ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
168 let mut err = struct_span_err!(
172 "the name `{}` is already used for a generic \
173 parameter in this item's generic parameters",
176 err.span_label(span, "already used");
177 err.span_label(first_use_span, format!("first use of `{}`", name));
180 ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
181 let mut err = struct_span_err!(
185 "method `{}` is not a member of trait `{}`",
189 err.span_label(span, format!("not a member of trait `{}`", trait_));
192 ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
193 let mut err = struct_span_err!(
197 "type `{}` is not a member of trait `{}`",
201 err.span_label(span, format!("not a member of trait `{}`", trait_));
204 ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
205 let mut err = struct_span_err!(
209 "const `{}` is not a member of trait `{}`",
213 err.span_label(span, format!("not a member of trait `{}`", trait_));
216 ResolutionError::VariableNotBoundInPattern(binding_error) => {
217 let BindingError { name, target, origin, could_be_path } = binding_error;
219 let target_sp = target.iter().copied().collect::<Vec<_>>();
220 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
222 let msp = MultiSpan::from_spans(target_sp.clone());
223 let mut err = struct_span_err!(
227 "variable `{}` is not bound in all patterns",
230 for sp in target_sp {
231 err.span_label(sp, format!("pattern doesn't bind `{}`", name));
233 for sp in origin_sp {
234 err.span_label(sp, "variable not in all patterns");
237 let help_msg = format!(
238 "if you meant to match on a variant or a `const` item, consider \
239 making the path in the pattern qualified: `?::{}`",
242 err.span_help(span, &help_msg);
246 ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
247 let mut err = struct_span_err!(
251 "variable `{}` is bound in inconsistent \
252 ways within the same match arm",
255 err.span_label(span, "bound in different ways");
256 err.span_label(first_binding_span, "first binding");
259 ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
260 let mut err = struct_span_err!(
264 "identifier `{}` is bound more than once in this parameter list",
267 err.span_label(span, "used as parameter more than once");
270 ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
271 let mut err = struct_span_err!(
275 "identifier `{}` is bound more than once in the same pattern",
278 err.span_label(span, "used in a pattern more than once");
281 ResolutionError::UndeclaredLabel(name, lev_candidate) => {
282 let mut err = struct_span_err!(
286 "use of undeclared label `{}`",
289 if let Some(lev_candidate) = lev_candidate {
292 "a label with a similar name exists in this scope",
293 lev_candidate.to_string(),
294 Applicability::MaybeIncorrect,
297 err.span_label(span, format!("undeclared label `{}`", name));
301 ResolutionError::SelfImportsOnlyAllowedWithin => struct_span_err!(
306 "`self` imports are only allowed within a { } list"
308 ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
309 let mut err = struct_span_err!(
313 "`self` import can only appear once in an import list"
315 err.span_label(span, "can only appear once in an import list");
318 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
319 let mut err = struct_span_err!(
323 "`self` import can only appear in an import list with \
326 err.span_label(span, "can only appear in an import list with a non-empty prefix");
329 ResolutionError::FailedToResolve { label, suggestion } => {
331 struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
332 err.span_label(span, label);
334 if let Some((suggestions, msg, applicability)) = suggestion {
335 err.multipart_suggestion(&msg, suggestions, applicability);
340 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
341 let mut err = struct_span_err!(
346 "can't capture dynamic environment in a fn item"
348 err.help("use the `|| { ... }` closure form instead");
351 ResolutionError::AttemptToUseNonConstantValueInConstant => {
352 let mut err = struct_span_err!(
356 "attempt to use a non-constant value in a constant"
358 err.span_label(span, "non-constant value");
361 ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
362 let res = binding.res();
363 let shadows_what = res.descr();
364 let mut err = struct_span_err!(
368 "{}s cannot shadow {}s",
374 format!("cannot be named the same as {} {}", res.article(), shadows_what),
376 let participle = if binding.is_import() { "imported" } else { "defined" };
377 let msg = format!("the {} `{}` is {} here", shadows_what, name, participle);
378 err.span_label(binding.span, msg);
381 ResolutionError::ForwardDeclaredTyParam => {
382 let mut err = struct_span_err!(
386 "type parameters with a default cannot use \
387 forward declared identifiers"
391 "defaulted type parameters cannot be forward declared".to_string(),
395 ResolutionError::SelfInTyParamDefault => {
396 let mut err = struct_span_err!(
400 "type parameters cannot use `Self` in their defaults"
402 err.span_label(span, "`Self` in type parameter default".to_string());
408 crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
409 match vis_resolution_error {
410 VisResolutionError::Relative2018(span, path) => {
411 let mut err = self.session.struct_span_err(
413 "relative paths are not supported in visibilities on 2018 edition",
418 format!("crate::{}", pprust::path_to_string(&path)),
419 Applicability::MaybeIncorrect,
423 VisResolutionError::AncestorOnly(span) => struct_span_err!(
427 "visibilities can only be restricted to ancestor modules"
429 VisResolutionError::FailedToResolve(span, label, suggestion) => {
430 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
432 VisResolutionError::ExpectedFound(span, path_str, res) => {
433 let mut err = struct_span_err!(
437 "expected module, found {} `{}`",
441 err.span_label(span, "not a module");
444 VisResolutionError::Indeterminate(span) => struct_span_err!(
448 "cannot determine resolution for the visibility"
450 VisResolutionError::ModuleOnly(span) => {
451 self.session.struct_span_err(span, "visibility must resolve to a module")
457 /// Lookup typo candidate in scope for a macro or import.
458 fn early_lookup_typo_candidate(
461 parent_scope: &ParentScope<'a>,
463 filter_fn: &impl Fn(Res) -> bool,
464 ) -> Option<TypoSuggestion> {
465 let mut suggestions = Vec::new();
466 self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
468 Scope::DeriveHelpers(expn_id) => {
469 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
476 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
480 Scope::DeriveHelpersCompat => {
481 let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
483 for derive in parent_scope.derives {
484 let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
485 if let Ok((Some(ext), _)) = this.resolve_macro_path(
487 Some(MacroKind::Derive),
495 .map(|name| TypoSuggestion::from_res(*name, res)),
501 Scope::MacroRules(legacy_scope) => {
502 if let LegacyScope::Binding(legacy_binding) = legacy_scope {
503 let res = legacy_binding.binding.res();
506 .push(TypoSuggestion::from_res(legacy_binding.ident.name, res))
510 Scope::CrateRoot => {
511 let root_ident = Ident::new(kw::PathRoot, ident.span);
512 let root_module = this.resolve_crate_root(root_ident);
513 this.add_module_candidates(root_module, &mut suggestions, filter_fn);
515 Scope::Module(module) => {
516 this.add_module_candidates(module, &mut suggestions, filter_fn);
518 Scope::RegisteredAttrs => {
519 let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
522 this.registered_attrs
524 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
528 Scope::MacroUsePrelude => {
529 suggestions.extend(this.macro_use_prelude.iter().filter_map(
531 let res = binding.res();
532 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
536 Scope::BuiltinAttrs => {
537 let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
542 .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
546 Scope::ExternPrelude => {
547 suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
548 let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
549 filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
552 Scope::ToolPrelude => {
553 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
555 this.registered_tools
557 .map(|ident| TypoSuggestion::from_res(ident.name, res)),
560 Scope::StdLibPrelude => {
561 if let Some(prelude) = this.prelude {
562 let mut tmp_suggestions = Vec::new();
563 this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
567 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
571 Scope::BuiltinTypes => {
572 let primitive_types = &this.primitive_type_table.primitive_types;
573 suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| {
574 let res = Res::PrimTy(*prim_ty);
575 filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
583 // Make sure error reporting is deterministic.
584 suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
586 match find_best_match_for_name(
587 suggestions.iter().map(|suggestion| &suggestion.candidate),
591 Some(found) if found != ident.name => {
592 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
598 fn lookup_import_candidates_from_module<FilterFn>(
601 namespace: Namespace,
602 start_module: Module<'a>,
605 ) -> Vec<ImportSuggestion>
607 FilterFn: Fn(Res) -> bool,
609 let mut candidates = Vec::new();
610 let mut seen_modules = FxHashSet::default();
611 let not_local_module = crate_name.name != kw::Crate;
612 let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), not_local_module)];
614 while let Some((in_module, path_segments, in_module_is_extern)) = worklist.pop() {
615 // We have to visit module children in deterministic order to avoid
616 // instabilities in reported imports (#43552).
617 in_module.for_each_child(self, |this, ident, ns, name_binding| {
618 // avoid imports entirely
619 if name_binding.is_import() && !name_binding.is_extern_crate() {
622 // avoid non-importable candidates as well
623 if !name_binding.is_importable() {
627 // collect results based on the filter function
628 if ident.name == lookup_ident.name && ns == namespace {
629 let res = name_binding.res();
632 let mut segms = path_segments.clone();
633 if lookup_ident.span.rust_2018() {
634 // crate-local absolute paths start with `crate::` in edition 2018
635 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
636 segms.insert(0, ast::PathSegment::from_ident(crate_name));
639 segms.push(ast::PathSegment::from_ident(ident));
640 let path = Path { span: name_binding.span, segments: segms };
641 // the entity is accessible in the following cases:
642 // 1. if it's defined in the same crate, it's always
643 // accessible (since private entities can be made public)
644 // 2. if it's defined in another crate, it's accessible
645 // only if both the module is public and the entity is
646 // declared as public (due to pruning, we don't explore
647 // outside crate private modules => no need to check this)
648 if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
649 let did = match res {
650 Res::Def(DefKind::Ctor(..), did) => this.parent(did),
651 _ => res.opt_def_id(),
653 candidates.push(ImportSuggestion { did, path });
658 // collect submodules to explore
659 if let Some(module) = name_binding.module() {
661 let mut path_segments = path_segments.clone();
662 path_segments.push(ast::PathSegment::from_ident(ident));
664 let is_extern_crate_that_also_appears_in_prelude =
665 name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
667 let is_visible_to_user =
668 !in_module_is_extern || name_binding.vis == ty::Visibility::Public;
670 if !is_extern_crate_that_also_appears_in_prelude && is_visible_to_user {
671 // add the module to the lookup
672 let is_extern = in_module_is_extern || name_binding.is_extern_crate();
673 if seen_modules.insert(module.def_id().unwrap()) {
674 worklist.push((module, path_segments, is_extern));
684 /// When name resolution fails, this method can be used to look up candidate
685 /// entities with the expected name. It allows filtering them using the
686 /// supplied predicate (which should be used to only accept the types of
687 /// definitions expected, e.g., traits). The lookup spans across all crates.
689 /// N.B., the method does not look into imports, but this is not a problem,
690 /// since we report the definitions (thus, the de-aliased imports).
691 crate fn lookup_import_candidates<FilterFn>(
694 namespace: Namespace,
696 ) -> Vec<ImportSuggestion>
698 FilterFn: Fn(Res) -> bool,
700 let mut suggestions = self.lookup_import_candidates_from_module(
704 Ident::with_dummy_span(kw::Crate),
708 if lookup_ident.span.rust_2018() {
709 let extern_prelude_names = self.extern_prelude.clone();
710 for (ident, _) in extern_prelude_names.into_iter() {
711 if ident.span.from_expansion() {
712 // Idents are adjusted to the root context before being
713 // resolved in the extern prelude, so reporting this to the
714 // user is no help. This skips the injected
715 // `extern crate std` in the 2018 edition, which would
716 // otherwise cause duplicate suggestions.
719 if let Some(crate_id) =
720 self.crate_loader.maybe_process_path_extern(ident.name, ident.span)
723 self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
724 suggestions.extend(self.lookup_import_candidates_from_module(
738 crate fn unresolved_macro_suggestions(
740 err: &mut DiagnosticBuilder<'a>,
741 macro_kind: MacroKind,
742 parent_scope: &ParentScope<'a>,
745 let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
746 let suggestion = self.early_lookup_typo_candidate(
747 ScopeSet::Macro(macro_kind),
752 self.add_typo_suggestion(err, suggestion, ident.span);
754 if macro_kind == MacroKind::Derive && (ident.as_str() == "Send" || ident.as_str() == "Sync")
756 let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
757 err.span_note(ident.span, &msg);
759 if self.macro_names.contains(&ident.modern()) {
760 err.help("have you added the `#[macro_use]` on the module/import?");
764 crate fn add_typo_suggestion(
766 err: &mut DiagnosticBuilder<'_>,
767 suggestion: Option<TypoSuggestion>,
770 if let Some(suggestion) = suggestion {
771 // We shouldn't suggest underscore.
772 if suggestion.candidate == kw::Underscore {
777 "{} {} with a similar name exists",
778 suggestion.res.article(),
779 suggestion.res.descr()
784 suggestion.candidate.to_string(),
785 Applicability::MaybeIncorrect,
787 let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
788 LOCAL_CRATE => self.definitions.opt_span(def_id),
792 .def_span(self.cstore().get_span_untracked(def_id, self.session)),
795 if let Some(span) = def_span {
799 "similarly named {} `{}` defined here",
800 suggestion.res.descr(),
801 suggestion.candidate.as_str(),
810 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
812 if b.span.is_dummy() {
813 let add_built_in = match b.res() {
814 // These already contain the "built-in" prefix or look bad with it.
815 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
818 let (built_in, from) = if from_prelude {
819 ("", " from prelude")
820 } else if b.is_extern_crate()
822 && self.session.opts.externs.get(&ident.as_str()).is_some()
824 ("", " passed with `--extern`")
825 } else if add_built_in {
831 let article = if built_in.is_empty() { res.article() } else { "a" };
833 "{a}{built_in} {thing}{from}",
840 let introduced = if b.is_import() { "imported" } else { "defined" };
841 format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced)
845 crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
846 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
847 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
848 // We have to print the span-less alternative first, otherwise formatting looks bad.
849 (b2, b1, misc2, misc1, true)
851 (b1, b2, misc1, misc2, false)
854 let mut err = struct_span_err!(
858 "`{ident}` is ambiguous ({why})",
862 err.span_label(ident.span, "ambiguous name");
864 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
865 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
866 let note_msg = format!(
867 "`{ident}` could{also} refer to {what}",
873 let thing = b.res().descr();
874 let mut help_msgs = Vec::new();
875 if b.is_glob_import()
876 && (kind == AmbiguityKind::GlobVsGlob
877 || kind == AmbiguityKind::GlobVsExpanded
878 || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
880 help_msgs.push(format!(
881 "consider adding an explicit import of \
882 `{ident}` to disambiguate",
886 if b.is_extern_crate() && ident.span.rust_2018() {
887 help_msgs.push(format!(
888 "use `::{ident}` to refer to this {thing} unambiguously",
893 if misc == AmbiguityErrorMisc::SuggestCrate {
894 help_msgs.push(format!(
895 "use `crate::{ident}` to refer to this {thing} unambiguously",
899 } else if misc == AmbiguityErrorMisc::SuggestSelf {
900 help_msgs.push(format!(
901 "use `self::{ident}` to refer to this {thing} unambiguously",
907 err.span_note(b.span, ¬e_msg);
908 for (i, help_msg) in help_msgs.iter().enumerate() {
909 let or = if i == 0 { "" } else { "or " };
910 err.help(&format!("{}{}", or, help_msg));
914 could_refer_to(b1, misc1, "");
915 could_refer_to(b2, misc2, " also");
919 crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
920 let PrivacyError { ident, binding, .. } = *privacy_error;
921 let session = &self.session;
922 let mk_struct_span_error = |is_constructor| {
923 let mut descr = binding.res().descr().to_string();
925 descr += " constructor";
927 if binding.is_import() {
932 struct_span_err!(session, ident.span, E0603, "{} `{}` is private", descr, ident);
934 err.span_label(ident.span, &format!("this {} is private", descr));
936 session.source_map().def_span(binding.span),
937 &format!("the {} `{}` is defined here", descr, ident),
943 let mut err = if let NameBindingKind::Res(
944 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
948 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
949 if let Some(fields) = self.field_names.get(&def_id) {
950 let mut err = mk_struct_span_error(true);
951 let first_field = fields.first().expect("empty field list in the map");
953 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
954 "a constructor is private if any of the fields is private",
958 mk_struct_span_error(false)
961 mk_struct_span_error(false)
968 impl<'a, 'b> ImportResolver<'a, 'b> {
969 /// Adds suggestions for a path that cannot be resolved.
970 pub(crate) fn make_path_suggestion(
973 mut path: Vec<Segment>,
974 parent_scope: &ParentScope<'b>,
975 ) -> Option<(Vec<Segment>, Vec<String>)> {
976 debug!("make_path_suggestion: span={:?} path={:?}", span, path);
978 match (path.get(0), path.get(1)) {
979 // `{{root}}::ident::...` on both editions.
980 // On 2015 `{{root}}` is usually added implicitly.
981 (Some(fst), Some(snd))
982 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
983 // `ident::...` on 2018.
985 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
987 // Insert a placeholder that's later replaced by `self`/`super`/etc.
988 path.insert(0, Segment::from_ident(Ident::invalid()));
993 self.make_missing_self_suggestion(span, path.clone(), parent_scope)
994 .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
995 .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
996 .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
999 /// Suggest a missing `self::` if that resolves to an correct module.
1003 /// LL | use foo::Bar;
1004 /// | ^^^ did you mean `self::foo`?
1006 fn make_missing_self_suggestion(
1009 mut path: Vec<Segment>,
1010 parent_scope: &ParentScope<'b>,
1011 ) -> Option<(Vec<Segment>, Vec<String>)> {
1012 // Replace first ident with `self` and check if that is valid.
1013 path[0].ident.name = kw::SelfLower;
1014 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1015 debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1016 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1019 /// Suggests a missing `crate::` if that resolves to an correct module.
1023 /// LL | use foo::Bar;
1024 /// | ^^^ did you mean `crate::foo`?
1026 fn make_missing_crate_suggestion(
1029 mut path: Vec<Segment>,
1030 parent_scope: &ParentScope<'b>,
1031 ) -> Option<(Vec<Segment>, Vec<String>)> {
1032 // Replace first ident with `crate` and check if that is valid.
1033 path[0].ident.name = kw::Crate;
1034 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1035 debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
1036 if let PathResult::Module(..) = result {
1040 "`use` statements changed in Rust 2018; read more at \
1041 <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1051 /// Suggests a missing `super::` if that resolves to an correct module.
1055 /// LL | use foo::Bar;
1056 /// | ^^^ did you mean `super::foo`?
1058 fn make_missing_super_suggestion(
1061 mut path: Vec<Segment>,
1062 parent_scope: &ParentScope<'b>,
1063 ) -> Option<(Vec<Segment>, Vec<String>)> {
1064 // Replace first ident with `crate` and check if that is valid.
1065 path[0].ident.name = kw::Super;
1066 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1067 debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
1068 if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1071 /// Suggests a missing external crate name if that resolves to an correct module.
1075 /// LL | use foobar::Baz;
1076 /// | ^^^^^^ did you mean `baz::foobar`?
1079 /// Used when importing a submodule of an external crate but missing that crate's
1080 /// name as the first part of path.
1081 fn make_external_crate_suggestion(
1084 mut path: Vec<Segment>,
1085 parent_scope: &ParentScope<'b>,
1086 ) -> Option<(Vec<Segment>, Vec<String>)> {
1087 if path[1].ident.span.rust_2015() {
1091 // Sort extern crate names in reverse order to get
1092 // 1) some consistent ordering for emitted dignostics, and
1093 // 2) `std` suggestions before `core` suggestions.
1094 let mut extern_crate_names =
1095 self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1096 extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
1098 for name in extern_crate_names.into_iter() {
1099 // Replace first ident with a crate name and check if that is valid.
1100 path[0].ident.name = name;
1101 let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
1103 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1106 if let PathResult::Module(..) = result {
1107 return Some((path, Vec::new()));
1114 /// Suggests importing a macro from the root of the crate rather than a module within
1118 /// help: a macro with this name exists at the root of the crate
1120 /// LL | use issue_59764::makro;
1121 /// | ^^^^^^^^^^^^^^^^^^
1123 /// = note: this could be because a macro annotated with `#[macro_export]` will be exported
1124 /// at the root of the crate instead of the module where it is defined
1126 pub(crate) fn check_for_module_export_macro(
1128 directive: &'b ImportDirective<'b>,
1129 module: ModuleOrUniformRoot<'b>,
1131 ) -> Option<(Option<Suggestion>, Vec<String>)> {
1132 let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
1138 while let Some(parent) = crate_module.parent {
1139 crate_module = parent;
1142 if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1143 // Don't make a suggestion if the import was already from the root of the
1148 let resolutions = self.r.resolutions(crate_module).borrow();
1149 let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1150 let binding = resolution.borrow().binding()?;
1151 if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1152 let module_name = crate_module.kind.name().unwrap();
1153 let import = match directive.subclass {
1154 ImportDirectiveSubclass::SingleImport { source, target, .. }
1155 if source != target =>
1157 format!("{} as {}", source, target)
1159 _ => format!("{}", ident),
1162 let mut corrections: Vec<(Span, String)> = Vec::new();
1163 if !directive.is_nested() {
1164 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1165 // intermediate segments.
1166 corrections.push((directive.span, format!("{}::{}", module_name, import)));
1168 // Find the binding span (and any trailing commas and spaces).
1169 // ie. `use a::b::{c, d, e};`
1171 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1177 "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1178 found_closing_brace, binding_span
1181 let mut removal_span = binding_span;
1182 if found_closing_brace {
1183 // If the binding span ended with a closing brace, as in the below example:
1184 // ie. `use a::b::{c, d};`
1186 // Then expand the span of characters to remove to include the previous
1187 // binding's trailing comma.
1188 // ie. `use a::b::{c, d};`
1190 if let Some(previous_span) =
1191 extend_span_to_previous_binding(self.r.session, binding_span)
1193 debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1194 removal_span = removal_span.with_lo(previous_span.lo());
1197 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1199 // Remove the `removal_span`.
1200 corrections.push((removal_span, "".to_string()));
1202 // Find the span after the crate name and if it has nested imports immediatately
1203 // after the crate name already.
1204 // ie. `use a::b::{c, d};`
1206 // or `use a::{b, c, d}};`
1208 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1214 "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1215 has_nested, after_crate_name
1218 let source_map = self.r.session.source_map();
1220 // Add the import to the start, with a `{` if required.
1221 let start_point = source_map.start_point(after_crate_name);
1222 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1226 // In this case, `start_snippet` must equal '{'.
1227 format!("{}{}, ", start_snippet, import)
1229 // In this case, add a `{`, then the moved import, then whatever
1230 // was there before.
1231 format!("{{{}, {}", import, start_snippet)
1236 // Add a `};` to the end if nested, matching the `{` added at the start.
1238 corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1242 let suggestion = Some((
1244 String::from("a macro with this name exists at the root of the crate"),
1245 Applicability::MaybeIncorrect,
1248 "this could be because a macro annotated with `#[macro_export]` will be exported \
1249 at the root of the crate instead of the module where it is defined"
1252 Some((suggestion, note))
1259 /// Given a `binding_span` of a binding within a use statement:
1262 /// use foo::{a, b, c};
1266 /// then return the span until the next binding or the end of the statement:
1269 /// use foo::{a, b, c};
1272 pub(crate) fn find_span_of_binding_until_next_binding(
1277 let source_map = sess.source_map();
1279 // Find the span of everything after the binding.
1280 // ie. `a, e};` or `a};`
1281 let binding_until_end = binding_span.with_hi(use_span.hi());
1283 // Find everything after the binding but not including the binding.
1284 // ie. `, e};` or `};`
1285 let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1287 // Keep characters in the span until we encounter something that isn't a comma or
1291 // Also note whether a closing brace character was encountered. If there
1292 // was, then later go backwards to remove any trailing commas that are left.
1293 let mut found_closing_brace = false;
1294 let after_binding_until_next_binding =
1295 source_map.span_take_while(after_binding_until_end, |&ch| {
1297 found_closing_brace = true;
1299 ch == ' ' || ch == ','
1302 // Combine the two spans.
1303 // ie. `a, ` or `a`.
1305 // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1306 let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1308 (found_closing_brace, span)
1311 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1315 /// use foo::a::{a, b, c};
1316 /// ^^--- binding span
1320 /// use foo::{a, b, c};
1321 /// --- binding span
1323 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1324 let source_map = sess.source_map();
1326 // `prev_source` will contain all of the source that came before the span.
1327 // Then split based on a command and take the first (ie. closest to our span)
1328 // snippet. In the example, this is a space.
1329 let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1331 let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1332 let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1333 if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1337 let prev_comma = prev_comma.first().unwrap();
1338 let prev_starting_brace = prev_starting_brace.first().unwrap();
1340 // If the amount of source code before the comma is greater than
1341 // the amount of source code before the starting brace then we've only
1342 // got one item in the nested item (eg. `issue_52891::{self}`).
1343 if prev_comma.len() > prev_starting_brace.len() {
1347 Some(binding_span.with_lo(BytePos(
1348 // Take away the number of bytes for the characters we've found and an
1349 // extra for the comma.
1350 binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1354 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1355 /// it is a nested use tree.
1358 /// use foo::a::{b, c};
1359 /// ^^^^^^^^^^ // false
1361 /// use foo::{a, b, c};
1362 /// ^^^^^^^^^^ // true
1364 /// use foo::{a, b::{c, d}};
1365 /// ^^^^^^^^^^^^^^^ // true
1367 fn find_span_immediately_after_crate_name(
1369 module_name: Symbol,
1373 "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1374 module_name, use_span
1376 let source_map = sess.source_map();
1378 // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1379 let mut num_colons = 0;
1380 // Find second colon.. `use issue_59764:`
1381 let until_second_colon = source_map.span_take_while(use_span, |c| {
1386 ':' if num_colons == 2 => false,
1390 // Find everything after the second colon.. `foo::{baz, makro};`
1391 let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1393 let mut found_a_non_whitespace_character = false;
1394 // Find the first non-whitespace character in `from_second_colon`.. `f`
1395 let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1396 if found_a_non_whitespace_character {
1399 if !c.is_whitespace() {
1400 found_a_non_whitespace_character = true;
1405 // Find the first `{` in from_second_colon.. `foo::{`
1406 let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1408 (next_left_bracket == after_second_colon, from_second_colon)
1411 /// When an entity with a given name is not available in scope, we search for
1412 /// entities with that name in all crates. This method allows outputting the
1413 /// results of this search in a programmer-friendly way
1414 crate fn show_candidates(
1415 err: &mut DiagnosticBuilder<'_>,
1416 // This is `None` if all placement locations are inside expansions
1418 candidates: &[ImportSuggestion],
1422 if candidates.is_empty() {
1425 // we want consistent results across executions, but candidates are produced
1426 // by iterating through a hash map, so make sure they are ordered:
1427 let mut path_strings: Vec<_> =
1428 candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
1429 path_strings.sort();
1430 path_strings.dedup();
1432 let better = if better { "better " } else { "" };
1433 let msg_diff = match path_strings.len() {
1434 1 => " is found in another module, you can import it",
1435 _ => "s are found in other modules, you can import them",
1437 let msg = format!("possible {}candidate{} into scope", better, msg_diff);
1439 if let Some(span) = span {
1440 for candidate in &mut path_strings {
1441 // produce an additional newline to separate the new use statement
1442 // from the directly following item.
1443 let additional_newline = if found_use { "" } else { "\n" };
1444 *candidate = format!("use {};\n{}", candidate, additional_newline);
1447 err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
1451 for candidate in path_strings {
1453 msg.push_str(&candidate);