use std::cmp::Reverse; use log::debug; use rustc::bug; use rustc::session::Session; use rustc::ty::{self, DefIdTree}; use rustc_ast_pretty::pprust; use rustc_data_structures::fx::FxHashSet; use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder}; use rustc_feature::BUILTIN_ATTRIBUTES; use rustc_hir as hir; use rustc_hir::def::Namespace::{self, *}; use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind}; use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE}; use rustc_span::hygiene::MacroKind; use rustc_span::source_map::SourceMap; use rustc_span::symbol::{kw, Symbol}; use rustc_span::{BytePos, MultiSpan, Span}; use syntax::ast::{self, Ident, Path}; use syntax::util::lev_distance::find_best_match_for_name; use crate::imports::{ImportDirective, ImportDirectiveSubclass, ImportResolver}; use crate::lifetimes::{ElisionFailureInfo, LifetimeContext}; use crate::path_names_to_string; use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind}; use crate::{BindingError, CrateLint, HasGenericParams, LegacyScope, Module, ModuleOrUniformRoot}; use crate::{NameBinding, NameBindingKind, PrivacyError, VisResolutionError}; use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment}; type Res = def::Res; /// A vector of spans and replacements, a message and applicability. crate type Suggestion = (Vec<(Span, String)>, String, Applicability); crate struct TypoSuggestion { pub candidate: Symbol, pub res: Res, } impl TypoSuggestion { crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion { TypoSuggestion { candidate, res } } } /// A free importable items suggested in case of resolution failure. crate struct ImportSuggestion { pub did: Option, pub path: Path, } crate enum MissingLifetimeSpot<'tcx> { Generics(&'tcx hir::Generics<'tcx>), HigherRanked { span: Span, span_type: ForLifetimeSpanType }, } crate enum ForLifetimeSpanType { BoundEmpty, BoundTail, TypeEmpty, TypeTail, } impl ForLifetimeSpanType { crate fn descr(&self) -> &'static str { match self { Self::BoundEmpty | Self::BoundTail => "bound", Self::TypeEmpty | Self::TypeTail => "type", } } crate fn suggestion(&self, sugg: &str) -> String { match self { Self::BoundEmpty | Self::TypeEmpty => format!("for<{}> ", sugg), Self::BoundTail | Self::TypeTail => format!(", {}", sugg), } } } impl<'tcx> Into> for &'tcx hir::Generics<'tcx> { fn into(self) -> MissingLifetimeSpot<'tcx> { MissingLifetimeSpot::Generics(self) } } /// Adjust the impl span so that just the `impl` keyword is taken by removing /// everything after `<` (`"impl Iterator for A {}" -> "impl"`) and /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`). /// /// *Attention*: the method used is very fragile since it essentially duplicates the work of the /// parser. If you need to use this function or something similar, please consider updating the /// `source_map` functions and this function to something more robust. fn reduce_impl_span_to_impl_keyword(cm: &SourceMap, impl_span: Span) -> Span { let impl_span = cm.span_until_char(impl_span, '<'); let impl_span = cm.span_until_whitespace(impl_span); impl_span } impl<'a> Resolver<'a> { crate fn add_module_candidates( &mut self, module: Module<'a>, names: &mut Vec, filter_fn: &impl Fn(Res) -> bool, ) { for (key, resolution) in self.resolutions(module).borrow().iter() { if let Some(binding) = resolution.borrow().binding { let res = binding.res(); if filter_fn(res) { names.push(TypoSuggestion::from_res(key.ident.name, res)); } } } } /// Combines an error with provided span and emits it. /// /// This takes the error provided, combines it with the span and any additional spans inside the /// error and emits it. crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) { self.into_struct_error(span, resolution_error).emit(); } crate fn into_struct_error( &self, span: Span, resolution_error: ResolutionError<'_>, ) -> DiagnosticBuilder<'_> { match resolution_error { ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => { let mut err = struct_span_err!( self.session, span, E0401, "can't use generic parameters from outer function", ); err.span_label(span, format!("use of generic parameter from outer function")); let cm = self.session.source_map(); match outer_res { Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => { if let Some(impl_span) = maybe_impl_defid.and_then(|def_id| self.definitions.opt_span(def_id)) { err.span_label( reduce_impl_span_to_impl_keyword(cm, impl_span), "`Self` type implicitly declared here, by this `impl`", ); } match (maybe_trait_defid, maybe_impl_defid) { (Some(_), None) => { err.span_label(span, "can't use `Self` here"); } (_, Some(_)) => { err.span_label(span, "use a type here instead"); } (None, None) => bug!("`impl` without trait nor type?"), } return err; } Res::Def(DefKind::TyParam, def_id) => { if let Some(span) = self.definitions.opt_span(def_id) { err.span_label(span, "type parameter from outer function"); } } Res::Def(DefKind::ConstParam, def_id) => { if let Some(span) = self.definitions.opt_span(def_id) { err.span_label(span, "const parameter from outer function"); } } _ => { bug!( "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \ DefKind::TyParam" ); } } if has_generic_params == HasGenericParams::Yes { // Try to retrieve the span of the function signature and generate a new // message with a local type or const parameter. let sugg_msg = &format!("try using a local generic parameter instead"); if let Some((sugg_span, snippet)) = cm.generate_local_type_param_snippet(span) { // Suggest the modification to the user err.span_suggestion( sugg_span, sugg_msg, snippet, Applicability::MachineApplicable, ); } else if let Some(sp) = cm.generate_fn_name_span(span) { err.span_label( sp, format!("try adding a local generic parameter in this method instead"), ); } else { err.help(&format!("try using a local generic parameter instead")); } } err } ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => { let mut err = struct_span_err!( self.session, span, E0403, "the name `{}` is already used for a generic \ parameter in this item's generic parameters", name, ); err.span_label(span, "already used"); err.span_label(first_use_span, format!("first use of `{}`", name)); err } ResolutionError::MethodNotMemberOfTrait(method, trait_) => { let mut err = struct_span_err!( self.session, span, E0407, "method `{}` is not a member of trait `{}`", method, trait_ ); err.span_label(span, format!("not a member of trait `{}`", trait_)); err } ResolutionError::TypeNotMemberOfTrait(type_, trait_) => { let mut err = struct_span_err!( self.session, span, E0437, "type `{}` is not a member of trait `{}`", type_, trait_ ); err.span_label(span, format!("not a member of trait `{}`", trait_)); err } ResolutionError::ConstNotMemberOfTrait(const_, trait_) => { let mut err = struct_span_err!( self.session, span, E0438, "const `{}` is not a member of trait `{}`", const_, trait_ ); err.span_label(span, format!("not a member of trait `{}`", trait_)); err } ResolutionError::VariableNotBoundInPattern(binding_error) => { let BindingError { name, target, origin, could_be_path } = binding_error; let target_sp = target.iter().copied().collect::>(); let origin_sp = origin.iter().copied().collect::>(); let msp = MultiSpan::from_spans(target_sp.clone()); let mut err = struct_span_err!( self.session, msp, E0408, "variable `{}` is not bound in all patterns", name, ); for sp in target_sp { err.span_label(sp, format!("pattern doesn't bind `{}`", name)); } for sp in origin_sp { err.span_label(sp, "variable not in all patterns"); } if *could_be_path { let help_msg = format!( "if you meant to match on a variant or a `const` item, consider \ making the path in the pattern qualified: `?::{}`", name, ); err.span_help(span, &help_msg); } err } ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => { let mut err = struct_span_err!( self.session, span, E0409, "variable `{}` is bound in inconsistent \ ways within the same match arm", variable_name ); err.span_label(span, "bound in different ways"); err.span_label(first_binding_span, "first binding"); err } ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => { let mut err = struct_span_err!( self.session, span, E0415, "identifier `{}` is bound more than once in this parameter list", identifier ); err.span_label(span, "used as parameter more than once"); err } ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => { let mut err = struct_span_err!( self.session, span, E0416, "identifier `{}` is bound more than once in the same pattern", identifier ); err.span_label(span, "used in a pattern more than once"); err } ResolutionError::UndeclaredLabel(name, lev_candidate) => { let mut err = struct_span_err!( self.session, span, E0426, "use of undeclared label `{}`", name ); if let Some(lev_candidate) = lev_candidate { err.span_suggestion( span, "a label with a similar name exists in this scope", lev_candidate.to_string(), Applicability::MaybeIncorrect, ); } else { err.span_label(span, format!("undeclared label `{}`", name)); } err } ResolutionError::SelfImportsOnlyAllowedWithin => struct_span_err!( self.session, span, E0429, "{}", "`self` imports are only allowed within a { } list" ), ResolutionError::SelfImportCanOnlyAppearOnceInTheList => { let mut err = struct_span_err!( self.session, span, E0430, "`self` import can only appear once in an import list" ); err.span_label(span, "can only appear once in an import list"); err } ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => { let mut err = struct_span_err!( self.session, span, E0431, "`self` import can only appear in an import list with \ a non-empty prefix" ); err.span_label(span, "can only appear in an import list with a non-empty prefix"); err } ResolutionError::FailedToResolve { label, suggestion } => { let mut err = struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label); err.span_label(span, label); if let Some((suggestions, msg, applicability)) = suggestion { err.multipart_suggestion(&msg, suggestions, applicability); } err } ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => { let mut err = struct_span_err!( self.session, span, E0434, "{}", "can't capture dynamic environment in a fn item" ); err.help("use the `|| { ... }` closure form instead"); err } ResolutionError::AttemptToUseNonConstantValueInConstant => { let mut err = struct_span_err!( self.session, span, E0435, "attempt to use a non-constant value in a constant" ); err.span_label(span, "non-constant value"); err } ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => { let res = binding.res(); let shadows_what = res.descr(); let mut err = struct_span_err!( self.session, span, E0530, "{}s cannot shadow {}s", what_binding, shadows_what ); err.span_label( span, format!("cannot be named the same as {} {}", res.article(), shadows_what), ); let participle = if binding.is_import() { "imported" } else { "defined" }; let msg = format!("the {} `{}` is {} here", shadows_what, name, participle); err.span_label(binding.span, msg); err } ResolutionError::ForwardDeclaredTyParam => { let mut err = struct_span_err!( self.session, span, E0128, "type parameters with a default cannot use \ forward declared identifiers" ); err.span_label( span, "defaulted type parameters cannot be forward declared".to_string(), ); err } ResolutionError::SelfInTyParamDefault => { let mut err = struct_span_err!( self.session, span, E0735, "type parameters cannot use `Self` in their defaults" ); err.span_label(span, "`Self` in type parameter default".to_string()); err } } } crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) { match vis_resolution_error { VisResolutionError::Relative2018(span, path) => { let mut err = self.session.struct_span_err( span, "relative paths are not supported in visibilities on 2018 edition", ); err.span_suggestion( path.span, "try", format!("crate::{}", pprust::path_to_string(&path)), Applicability::MaybeIncorrect, ); err } VisResolutionError::AncestorOnly(span) => struct_span_err!( self.session, span, E0742, "visibilities can only be restricted to ancestor modules" ), VisResolutionError::FailedToResolve(span, label, suggestion) => { self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion }) } VisResolutionError::ExpectedFound(span, path_str, res) => { let mut err = struct_span_err!( self.session, span, E0577, "expected module, found {} `{}`", res.descr(), path_str ); err.span_label(span, "not a module"); err } VisResolutionError::Indeterminate(span) => struct_span_err!( self.session, span, E0578, "cannot determine resolution for the visibility" ), VisResolutionError::ModuleOnly(span) => { self.session.struct_span_err(span, "visibility must resolve to a module") } } .emit() } /// Lookup typo candidate in scope for a macro or import. fn early_lookup_typo_candidate( &mut self, scope_set: ScopeSet, parent_scope: &ParentScope<'a>, ident: Ident, filter_fn: &impl Fn(Res) -> bool, ) -> Option { let mut suggestions = Vec::new(); self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| { match scope { Scope::DeriveHelpers(expn_id) => { let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper); if filter_fn(res) { suggestions.extend( this.helper_attrs .get(&expn_id) .into_iter() .flatten() .map(|ident| TypoSuggestion::from_res(ident.name, res)), ); } } Scope::DeriveHelpersCompat => { let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper); if filter_fn(res) { for derive in parent_scope.derives { let parent_scope = &ParentScope { derives: &[], ..*parent_scope }; if let Ok((Some(ext), _)) = this.resolve_macro_path( derive, Some(MacroKind::Derive), parent_scope, false, false, ) { suggestions.extend( ext.helper_attrs .iter() .map(|name| TypoSuggestion::from_res(*name, res)), ); } } } } Scope::MacroRules(legacy_scope) => { if let LegacyScope::Binding(legacy_binding) = legacy_scope { let res = legacy_binding.binding.res(); if filter_fn(res) { suggestions .push(TypoSuggestion::from_res(legacy_binding.ident.name, res)) } } } Scope::CrateRoot => { let root_ident = Ident::new(kw::PathRoot, ident.span); let root_module = this.resolve_crate_root(root_ident); this.add_module_candidates(root_module, &mut suggestions, filter_fn); } Scope::Module(module) => { this.add_module_candidates(module, &mut suggestions, filter_fn); } Scope::RegisteredAttrs => { let res = Res::NonMacroAttr(NonMacroAttrKind::Registered); if filter_fn(res) { suggestions.extend( this.registered_attrs .iter() .map(|ident| TypoSuggestion::from_res(ident.name, res)), ); } } Scope::MacroUsePrelude => { suggestions.extend(this.macro_use_prelude.iter().filter_map( |(name, binding)| { let res = binding.res(); filter_fn(res).then_some(TypoSuggestion::from_res(*name, res)) }, )); } Scope::BuiltinAttrs => { let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin); if filter_fn(res) { suggestions.extend( BUILTIN_ATTRIBUTES .iter() .map(|(name, ..)| TypoSuggestion::from_res(*name, res)), ); } } Scope::ExternPrelude => { suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| { let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX)); filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res)) })); } Scope::ToolPrelude => { let res = Res::NonMacroAttr(NonMacroAttrKind::Tool); suggestions.extend( this.registered_tools .iter() .map(|ident| TypoSuggestion::from_res(ident.name, res)), ); } Scope::StdLibPrelude => { if let Some(prelude) = this.prelude { let mut tmp_suggestions = Vec::new(); this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn); suggestions.extend( tmp_suggestions .into_iter() .filter(|s| use_prelude || this.is_builtin_macro(s.res)), ); } } Scope::BuiltinTypes => { let primitive_types = &this.primitive_type_table.primitive_types; suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| { let res = Res::PrimTy(*prim_ty); filter_fn(res).then_some(TypoSuggestion::from_res(*name, res)) })) } } None::<()> }); // Make sure error reporting is deterministic. suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str()); match find_best_match_for_name( suggestions.iter().map(|suggestion| &suggestion.candidate), &ident.as_str(), None, ) { Some(found) if found != ident.name => { suggestions.into_iter().find(|suggestion| suggestion.candidate == found) } _ => None, } } fn lookup_import_candidates_from_module( &mut self, lookup_ident: Ident, namespace: Namespace, start_module: Module<'a>, crate_name: Ident, filter_fn: FilterFn, ) -> Vec where FilterFn: Fn(Res) -> bool, { let mut candidates = Vec::new(); let mut seen_modules = FxHashSet::default(); let not_local_module = crate_name.name != kw::Crate; let mut worklist = vec![(start_module, Vec::::new(), not_local_module)]; while let Some((in_module, path_segments, in_module_is_extern)) = worklist.pop() { // We have to visit module children in deterministic order to avoid // instabilities in reported imports (#43552). in_module.for_each_child(self, |this, ident, ns, name_binding| { // avoid imports entirely if name_binding.is_import() && !name_binding.is_extern_crate() { return; } // avoid non-importable candidates as well if !name_binding.is_importable() { return; } // collect results based on the filter function if ident.name == lookup_ident.name && ns == namespace { let res = name_binding.res(); if filter_fn(res) { // create the path let mut segms = path_segments.clone(); if lookup_ident.span.rust_2018() { // crate-local absolute paths start with `crate::` in edition 2018 // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660) segms.insert(0, ast::PathSegment::from_ident(crate_name)); } segms.push(ast::PathSegment::from_ident(ident)); let path = Path { span: name_binding.span, segments: segms }; // the entity is accessible in the following cases: // 1. if it's defined in the same crate, it's always // accessible (since private entities can be made public) // 2. if it's defined in another crate, it's accessible // only if both the module is public and the entity is // declared as public (due to pruning, we don't explore // outside crate private modules => no need to check this) if !in_module_is_extern || name_binding.vis == ty::Visibility::Public { let did = match res { Res::Def(DefKind::Ctor(..), did) => this.parent(did), _ => res.opt_def_id(), }; candidates.push(ImportSuggestion { did, path }); } } } // collect submodules to explore if let Some(module) = name_binding.module() { // form the path let mut path_segments = path_segments.clone(); path_segments.push(ast::PathSegment::from_ident(ident)); let is_extern_crate_that_also_appears_in_prelude = name_binding.is_extern_crate() && lookup_ident.span.rust_2018(); let is_visible_to_user = !in_module_is_extern || name_binding.vis == ty::Visibility::Public; if !is_extern_crate_that_also_appears_in_prelude && is_visible_to_user { // add the module to the lookup let is_extern = in_module_is_extern || name_binding.is_extern_crate(); if seen_modules.insert(module.def_id().unwrap()) { worklist.push((module, path_segments, is_extern)); } } } }) } candidates } /// When name resolution fails, this method can be used to look up candidate /// entities with the expected name. It allows filtering them using the /// supplied predicate (which should be used to only accept the types of /// definitions expected, e.g., traits). The lookup spans across all crates. /// /// N.B., the method does not look into imports, but this is not a problem, /// since we report the definitions (thus, the de-aliased imports). crate fn lookup_import_candidates( &mut self, lookup_ident: Ident, namespace: Namespace, filter_fn: FilterFn, ) -> Vec where FilterFn: Fn(Res) -> bool, { let mut suggestions = self.lookup_import_candidates_from_module( lookup_ident, namespace, self.graph_root, Ident::with_dummy_span(kw::Crate), &filter_fn, ); if lookup_ident.span.rust_2018() { let extern_prelude_names = self.extern_prelude.clone(); for (ident, _) in extern_prelude_names.into_iter() { if ident.span.from_expansion() { // Idents are adjusted to the root context before being // resolved in the extern prelude, so reporting this to the // user is no help. This skips the injected // `extern crate std` in the 2018 edition, which would // otherwise cause duplicate suggestions. continue; } if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name, ident.span) { let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX }); suggestions.extend(self.lookup_import_candidates_from_module( lookup_ident, namespace, crate_root, ident, &filter_fn, )); } } } suggestions } crate fn unresolved_macro_suggestions( &mut self, err: &mut DiagnosticBuilder<'a>, macro_kind: MacroKind, parent_scope: &ParentScope<'a>, ident: Ident, ) { let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind); let suggestion = self.early_lookup_typo_candidate( ScopeSet::Macro(macro_kind), parent_scope, ident, is_expected, ); self.add_typo_suggestion(err, suggestion, ident.span); if macro_kind == MacroKind::Derive && (ident.as_str() == "Send" || ident.as_str() == "Sync") { let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident); err.span_note(ident.span, &msg); } if self.macro_names.contains(&ident.modern()) { err.help("have you added the `#[macro_use]` on the module/import?"); } } crate fn add_typo_suggestion( &self, err: &mut DiagnosticBuilder<'_>, suggestion: Option, span: Span, ) -> bool { if let Some(suggestion) = suggestion { // We shouldn't suggest underscore. if suggestion.candidate == kw::Underscore { return false; } let msg = format!( "{} {} with a similar name exists", suggestion.res.article(), suggestion.res.descr() ); err.span_suggestion( span, &msg, suggestion.candidate.to_string(), Applicability::MaybeIncorrect, ); let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate { LOCAL_CRATE => self.definitions.opt_span(def_id), _ => Some( self.session .source_map() .def_span(self.cstore().get_span_untracked(def_id, self.session)), ), }); if let Some(span) = def_span { err.span_label( span, &format!( "similarly named {} `{}` defined here", suggestion.res.descr(), suggestion.candidate.as_str(), ), ); } return true; } false } fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String { let res = b.res(); if b.span.is_dummy() { let add_built_in = match b.res() { // These already contain the "built-in" prefix or look bad with it. Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false, _ => true, }; let (built_in, from) = if from_prelude { ("", " from prelude") } else if b.is_extern_crate() && !b.is_import() && self.session.opts.externs.get(&ident.as_str()).is_some() { ("", " passed with `--extern`") } else if add_built_in { (" built-in", "") } else { ("", "") }; let article = if built_in.is_empty() { res.article() } else { "a" }; format!( "{a}{built_in} {thing}{from}", a = article, thing = res.descr(), built_in = built_in, from = from ) } else { let introduced = if b.is_import() { "imported" } else { "defined" }; format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced) } } crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) { let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error; let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() { // We have to print the span-less alternative first, otherwise formatting looks bad. (b2, b1, misc2, misc1, true) } else { (b1, b2, misc1, misc2, false) }; let mut err = struct_span_err!( self.session, ident.span, E0659, "`{ident}` is ambiguous ({why})", ident = ident, why = kind.descr() ); err.span_label(ident.span, "ambiguous name"); let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| { let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude); let note_msg = format!( "`{ident}` could{also} refer to {what}", ident = ident, also = also, what = what ); let thing = b.res().descr(); let mut help_msgs = Vec::new(); if b.is_glob_import() && (kind == AmbiguityKind::GlobVsGlob || kind == AmbiguityKind::GlobVsExpanded || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty()) { help_msgs.push(format!( "consider adding an explicit import of \ `{ident}` to disambiguate", ident = ident )) } if b.is_extern_crate() && ident.span.rust_2018() { help_msgs.push(format!( "use `::{ident}` to refer to this {thing} unambiguously", ident = ident, thing = thing, )) } if misc == AmbiguityErrorMisc::SuggestCrate { help_msgs.push(format!( "use `crate::{ident}` to refer to this {thing} unambiguously", ident = ident, thing = thing, )) } else if misc == AmbiguityErrorMisc::SuggestSelf { help_msgs.push(format!( "use `self::{ident}` to refer to this {thing} unambiguously", ident = ident, thing = thing, )) } err.span_note(b.span, ¬e_msg); for (i, help_msg) in help_msgs.iter().enumerate() { let or = if i == 0 { "" } else { "or " }; err.help(&format!("{}{}", or, help_msg)); } }; could_refer_to(b1, misc1, ""); could_refer_to(b2, misc2, " also"); err.emit(); } crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) { let PrivacyError { ident, binding, .. } = *privacy_error; let session = &self.session; let mk_struct_span_error = |is_constructor| { let mut descr = binding.res().descr().to_string(); if is_constructor { descr += " constructor"; } if binding.is_import() { descr += " import"; } let mut err = struct_span_err!(session, ident.span, E0603, "{} `{}` is private", descr, ident); err.span_label(ident.span, &format!("this {} is private", descr)); err.span_note( session.source_map().def_span(binding.span), &format!("the {} `{}` is defined here", descr, ident), ); err }; let mut err = if let NameBindingKind::Res( Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _, ) = binding.kind { let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor"); if let Some(fields) = self.field_names.get(&def_id) { let mut err = mk_struct_span_error(true); let first_field = fields.first().expect("empty field list in the map"); err.span_label( fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)), "a constructor is private if any of the fields is private", ); err } else { mk_struct_span_error(false) } } else { mk_struct_span_error(false) }; err.emit(); } } impl<'a, 'b> ImportResolver<'a, 'b> { /// Adds suggestions for a path that cannot be resolved. pub(crate) fn make_path_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Vec)> { debug!("make_path_suggestion: span={:?} path={:?}", span, path); match (path.get(0), path.get(1)) { // `{{root}}::ident::...` on both editions. // On 2015 `{{root}}` is usually added implicitly. (Some(fst), Some(snd)) if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {} // `ident::...` on 2018. (Some(fst), _) if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() => { // Insert a placeholder that's later replaced by `self`/`super`/etc. path.insert(0, Segment::from_ident(Ident::invalid())); } _ => return None, } self.make_missing_self_suggestion(span, path.clone(), parent_scope) .or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope)) .or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope)) .or_else(|| self.make_external_crate_suggestion(span, path, parent_scope)) } /// Suggest a missing `self::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `self::foo`? /// ``` fn make_missing_self_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Vec)> { // Replace first ident with `self` and check if that is valid. path[0].ident.name = kw::SelfLower; let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None } } /// Suggests a missing `crate::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `crate::foo`? /// ``` fn make_missing_crate_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Vec)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = kw::Crate; let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some(( path, vec![ "`use` statements changed in Rust 2018; read more at \ " .to_string(), ], )) } else { None } } /// Suggests a missing `super::` if that resolves to an correct module. /// /// ``` /// | /// LL | use foo::Bar; /// | ^^^ did you mean `super::foo`? /// ``` fn make_missing_super_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Vec)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = kw::Super; let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None } } /// Suggests a missing external crate name if that resolves to an correct module. /// /// ``` /// | /// LL | use foobar::Baz; /// | ^^^^^^ did you mean `baz::foobar`? /// ``` /// /// Used when importing a submodule of an external crate but missing that crate's /// name as the first part of path. fn make_external_crate_suggestion( &mut self, span: Span, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Vec)> { if path[1].ident.span.rust_2015() { return None; } // Sort extern crate names in reverse order to get // 1) some consistent ordering for emitted dignostics, and // 2) `std` suggestions before `core` suggestions. let mut extern_crate_names = self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::>(); extern_crate_names.sort_by_key(|name| Reverse(name.as_str())); for name in extern_crate_names.into_iter() { // Replace first ident with a crate name and check if that is valid. path[0].ident.name = name; let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No); debug!( "make_external_crate_suggestion: name={:?} path={:?} result={:?}", name, path, result ); if let PathResult::Module(..) = result { return Some((path, Vec::new())); } } None } /// Suggests importing a macro from the root of the crate rather than a module within /// the crate. /// /// ``` /// help: a macro with this name exists at the root of the crate /// | /// LL | use issue_59764::makro; /// | ^^^^^^^^^^^^^^^^^^ /// | /// = note: this could be because a macro annotated with `#[macro_export]` will be exported /// at the root of the crate instead of the module where it is defined /// ``` pub(crate) fn check_for_module_export_macro( &mut self, directive: &'b ImportDirective<'b>, module: ModuleOrUniformRoot<'b>, ident: Ident, ) -> Option<(Option, Vec)> { let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module { module } else { return None; }; while let Some(parent) = crate_module.parent { crate_module = parent; } if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) { // Don't make a suggestion if the import was already from the root of the // crate. return None; } let resolutions = self.r.resolutions(crate_module).borrow(); let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?; let binding = resolution.borrow().binding()?; if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() { let module_name = crate_module.kind.name().unwrap(); let import = match directive.subclass { ImportDirectiveSubclass::SingleImport { source, target, .. } if source != target => { format!("{} as {}", source, target) } _ => format!("{}", ident), }; let mut corrections: Vec<(Span, String)> = Vec::new(); if !directive.is_nested() { // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove // intermediate segments. corrections.push((directive.span, format!("{}::{}", module_name, import))); } else { // Find the binding span (and any trailing commas and spaces). // ie. `use a::b::{c, d, e};` // ^^^ let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding( self.r.session, directive.span, directive.use_span, ); debug!( "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}", found_closing_brace, binding_span ); let mut removal_span = binding_span; if found_closing_brace { // If the binding span ended with a closing brace, as in the below example: // ie. `use a::b::{c, d};` // ^ // Then expand the span of characters to remove to include the previous // binding's trailing comma. // ie. `use a::b::{c, d};` // ^^^ if let Some(previous_span) = extend_span_to_previous_binding(self.r.session, binding_span) { debug!("check_for_module_export_macro: previous_span={:?}", previous_span); removal_span = removal_span.with_lo(previous_span.lo()); } } debug!("check_for_module_export_macro: removal_span={:?}", removal_span); // Remove the `removal_span`. corrections.push((removal_span, "".to_string())); // Find the span after the crate name and if it has nested imports immediatately // after the crate name already. // ie. `use a::b::{c, d};` // ^^^^^^^^^ // or `use a::{b, c, d}};` // ^^^^^^^^^^^ let (has_nested, after_crate_name) = find_span_immediately_after_crate_name( self.r.session, module_name, directive.use_span, ); debug!( "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}", has_nested, after_crate_name ); let source_map = self.r.session.source_map(); // Add the import to the start, with a `{` if required. let start_point = source_map.start_point(after_crate_name); if let Ok(start_snippet) = source_map.span_to_snippet(start_point) { corrections.push(( start_point, if has_nested { // In this case, `start_snippet` must equal '{'. format!("{}{}, ", start_snippet, import) } else { // In this case, add a `{`, then the moved import, then whatever // was there before. format!("{{{}, {}", import, start_snippet) }, )); } // Add a `};` to the end if nested, matching the `{` added at the start. if !has_nested { corrections.push((source_map.end_point(after_crate_name), "};".to_string())); } } let suggestion = Some(( corrections, String::from("a macro with this name exists at the root of the crate"), Applicability::MaybeIncorrect, )); let note = vec![ "this could be because a macro annotated with `#[macro_export]` will be exported \ at the root of the crate instead of the module where it is defined" .to_string(), ]; Some((suggestion, note)) } else { None } } } /// Given a `binding_span` of a binding within a use statement: /// /// ``` /// use foo::{a, b, c}; /// ^ /// ``` /// /// then return the span until the next binding or the end of the statement: /// /// ``` /// use foo::{a, b, c}; /// ^^^ /// ``` pub(crate) fn find_span_of_binding_until_next_binding( sess: &Session, binding_span: Span, use_span: Span, ) -> (bool, Span) { let source_map = sess.source_map(); // Find the span of everything after the binding. // ie. `a, e};` or `a};` let binding_until_end = binding_span.with_hi(use_span.hi()); // Find everything after the binding but not including the binding. // ie. `, e};` or `};` let after_binding_until_end = binding_until_end.with_lo(binding_span.hi()); // Keep characters in the span until we encounter something that isn't a comma or // whitespace. // ie. `, ` or ``. // // Also note whether a closing brace character was encountered. If there // was, then later go backwards to remove any trailing commas that are left. let mut found_closing_brace = false; let after_binding_until_next_binding = source_map.span_take_while(after_binding_until_end, |&ch| { if ch == '}' { found_closing_brace = true; } ch == ' ' || ch == ',' }); // Combine the two spans. // ie. `a, ` or `a`. // // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };` let span = binding_span.with_hi(after_binding_until_next_binding.hi()); (found_closing_brace, span) } /// Given a `binding_span`, return the span through to the comma or opening brace of the previous /// binding. /// /// ``` /// use foo::a::{a, b, c}; /// ^^--- binding span /// | /// returned span /// /// use foo::{a, b, c}; /// --- binding span /// ``` pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option { let source_map = sess.source_map(); // `prev_source` will contain all of the source that came before the span. // Then split based on a command and take the first (ie. closest to our span) // snippet. In the example, this is a space. let prev_source = source_map.span_to_prev_source(binding_span).ok()?; let prev_comma = prev_source.rsplit(',').collect::>(); let prev_starting_brace = prev_source.rsplit('{').collect::>(); if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 { return None; } let prev_comma = prev_comma.first().unwrap(); let prev_starting_brace = prev_starting_brace.first().unwrap(); // If the amount of source code before the comma is greater than // the amount of source code before the starting brace then we've only // got one item in the nested item (eg. `issue_52891::{self}`). if prev_comma.len() > prev_starting_brace.len() { return None; } Some(binding_span.with_lo(BytePos( // Take away the number of bytes for the characters we've found and an // extra for the comma. binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1, ))) } /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if /// it is a nested use tree. /// /// ``` /// use foo::a::{b, c}; /// ^^^^^^^^^^ // false /// /// use foo::{a, b, c}; /// ^^^^^^^^^^ // true /// /// use foo::{a, b::{c, d}}; /// ^^^^^^^^^^^^^^^ // true /// ``` fn find_span_immediately_after_crate_name( sess: &Session, module_name: Symbol, use_span: Span, ) -> (bool, Span) { debug!( "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}", module_name, use_span ); let source_map = sess.source_map(); // Using `use issue_59764::foo::{baz, makro};` as an example throughout.. let mut num_colons = 0; // Find second colon.. `use issue_59764:` let until_second_colon = source_map.span_take_while(use_span, |c| { if *c == ':' { num_colons += 1; } match c { ':' if num_colons == 2 => false, _ => true, } }); // Find everything after the second colon.. `foo::{baz, makro};` let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1)); let mut found_a_non_whitespace_character = false; // Find the first non-whitespace character in `from_second_colon`.. `f` let after_second_colon = source_map.span_take_while(from_second_colon, |c| { if found_a_non_whitespace_character { return false; } if !c.is_whitespace() { found_a_non_whitespace_character = true; } true }); // Find the first `{` in from_second_colon.. `foo::{` let next_left_bracket = source_map.span_through_char(from_second_colon, '{'); (next_left_bracket == after_second_colon, from_second_colon) } /// When an entity with a given name is not available in scope, we search for /// entities with that name in all crates. This method allows outputting the /// results of this search in a programmer-friendly way crate fn show_candidates( err: &mut DiagnosticBuilder<'_>, // This is `None` if all placement locations are inside expansions span: Option, candidates: &[ImportSuggestion], better: bool, found_use: bool, ) { if candidates.is_empty() { return; } // we want consistent results across executions, but candidates are produced // by iterating through a hash map, so make sure they are ordered: let mut path_strings: Vec<_> = candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect(); path_strings.sort(); path_strings.dedup(); let better = if better { "better " } else { "" }; let msg_diff = match path_strings.len() { 1 => " is found in another module, you can import it", _ => "s are found in other modules, you can import them", }; let msg = format!("possible {}candidate{} into scope", better, msg_diff); if let Some(span) = span { for candidate in &mut path_strings { // produce an additional newline to separate the new use statement // from the directly following item. let additional_newline = if found_use { "" } else { "\n" }; *candidate = format!("use {};\n{}", candidate, additional_newline); } err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified); } else { let mut msg = msg; msg.push(':'); for candidate in path_strings { msg.push('\n'); msg.push_str(&candidate); } err.note(&msg); } } impl<'tcx> LifetimeContext<'_, 'tcx> { crate fn report_missing_lifetime_specifiers( &self, span: Span, count: usize, ) -> DiagnosticBuilder<'tcx> { struct_span_err!( self.tcx.sess, span, E0106, "missing lifetime specifier{}", pluralize!(count) ) } crate fn emit_undeclared_lifetime_error(&self, lifetime_ref: &hir::Lifetime) { let mut err = struct_span_err!( self.tcx.sess, lifetime_ref.span, E0261, "use of undeclared lifetime name `{}`", lifetime_ref ); err.span_label(lifetime_ref.span, "undeclared lifetime"); for missing in &self.missing_named_lifetime_spots { match missing { MissingLifetimeSpot::Generics(generics) => { let (span, sugg) = if let Some(param) = generics .params .iter() .filter(|p| match p.kind { hir::GenericParamKind::Type { synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), .. } => false, _ => true, }) .next() { (param.span.shrink_to_lo(), format!("{}, ", lifetime_ref)) } else { (generics.span, format!("<{}>", lifetime_ref)) }; err.span_suggestion( span, &format!("consider introducing lifetime `{}` here", lifetime_ref), sugg, Applicability::MaybeIncorrect, ); } MissingLifetimeSpot::HigherRanked { span, span_type } => { err.span_suggestion( *span, &format!( "consider making the {} lifetime-generic with a new `{}` lifetime", span_type.descr(), lifetime_ref ), span_type.suggestion(&lifetime_ref.to_string()), Applicability::MaybeIncorrect, ); err.note( "for more information on higher-ranked polymorphism, visit \ https://doc.rust-lang.org/nomicon/hrtb.html", ); } } } err.emit(); } crate fn is_trait_ref_fn_scope(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) -> bool { if let def::Res::Def(_, did) = trait_ref.trait_ref.path.res { if [ self.tcx.lang_items().fn_once_trait(), self.tcx.lang_items().fn_trait(), self.tcx.lang_items().fn_mut_trait(), ] .contains(&Some(did)) { let (span, span_type) = match &trait_ref.bound_generic_params { [] => (trait_ref.span.shrink_to_lo(), ForLifetimeSpanType::BoundEmpty), [.., bound] => (bound.span.shrink_to_hi(), ForLifetimeSpanType::BoundTail), }; self.missing_named_lifetime_spots .push(MissingLifetimeSpot::HigherRanked { span, span_type }); return true; } }; false } crate fn add_missing_lifetime_specifiers_label( &self, err: &mut DiagnosticBuilder<'_>, span: Span, count: usize, lifetime_names: &FxHashSet, params: &[ElisionFailureInfo], ) { if count > 1 { err.span_label(span, format!("expected {} lifetime parameters", count)); } else { let snippet = self.tcx.sess.source_map().span_to_snippet(span).ok(); let suggest_existing = |err: &mut DiagnosticBuilder<'_>, sugg| { err.span_suggestion( span, "consider using the named lifetime", sugg, Applicability::MaybeIncorrect, ); }; let suggest_new = |err: &mut DiagnosticBuilder<'_>, sugg: &str| { err.span_label(span, "expected named lifetime parameter"); for missing in self.missing_named_lifetime_spots.iter().rev() { let mut introduce_suggestion = vec![]; let msg; let should_break; introduce_suggestion.push(match missing { MissingLifetimeSpot::Generics(generics) => { msg = "consider introducing a named lifetime parameter".to_string(); should_break = true; if let Some(param) = generics.params.iter().filter(|p| match p.kind { hir::GenericParamKind::Type { synthetic: Some(hir::SyntheticTyParamKind::ImplTrait), .. } => false, _ => true, }).next() { (param.span.shrink_to_lo(), "'a, ".to_string()) } else { (generics.span, "<'a>".to_string()) } } MissingLifetimeSpot::HigherRanked { span, span_type } => { msg = format!( "consider making the {} lifetime-generic with a new `'a` lifetime", span_type.descr(), ); should_break = false; err.note( "for more information on higher-ranked polymorphism, visit \ https://doc.rust-lang.org/nomicon/hrtb.html", ); (*span, span_type.suggestion("'a")) } }); for param in params { if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(param.span) { if snippet.starts_with("&") && !snippet.starts_with("&'") { introduce_suggestion .push((param.span, format!("&'a {}", &snippet[1..]))); } else if snippet.starts_with("&'_ ") { introduce_suggestion .push((param.span, format!("&'a {}", &snippet[4..]))); } } } introduce_suggestion.push((span, sugg.to_string())); err.multipart_suggestion( &msg, introduce_suggestion, Applicability::MaybeIncorrect, ); if should_break { break; } } }; match ( lifetime_names.len(), lifetime_names.iter().next(), snippet.as_ref().map(|s| s.as_str()), ) { (1, Some(name), Some("&")) => { suggest_existing(err, format!("&{} ", name)); } (1, Some(name), Some("'_")) => { suggest_existing(err, name.to_string()); } (1, Some(name), Some(snippet)) if !snippet.ends_with(">") => { suggest_existing(err, format!("{}<{}>", snippet, name)); } (0, _, Some("&")) => { suggest_new(err, "&'a "); } (0, _, Some("'_")) => { suggest_new(err, "'a"); } (0, _, Some(snippet)) if !snippet.ends_with(">") => { suggest_new(err, &format!("{}<'a>", snippet)); } _ => { err.span_label(span, "expected lifetime parameter"); } } } } }