use std::ptr; use rustc_ast::ptr::P; use rustc_ast::visit::{self, Visitor}; use rustc_ast::{self as ast, Crate, ItemKind, ModKind, NodeId, Path, CRATE_NODE_ID}; use rustc_ast_pretty::pprust; use rustc_data_structures::fx::FxHashSet; use rustc_errors::struct_span_err; use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan}; use rustc_feature::BUILTIN_ATTRIBUTES; use rustc_hir::def::Namespace::{self, *}; use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind, PerNS}; use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE}; use rustc_hir::PrimTy; use rustc_index::vec::IndexVec; use rustc_middle::bug; use rustc_middle::ty::DefIdTree; use rustc_session::lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE; use rustc_session::lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS; use rustc_session::lint::BuiltinLintDiagnostics; use rustc_session::Session; use rustc_span::edition::Edition; use rustc_span::hygiene::MacroKind; use rustc_span::lev_distance::find_best_match_for_name; use rustc_span::source_map::SourceMap; use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::{BytePos, Span}; use crate::imports::{Import, ImportKind, ImportResolver}; use crate::late::{PatternSource, Rib}; use crate::path_names_to_string; use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, BindingError, Finalize}; use crate::{HasGenericParams, MacroRulesScope, Module, ModuleKind, ModuleOrUniformRoot}; use crate::{LexicalScopeBinding, NameBinding, NameBindingKind, PrivacyError, VisResolutionError}; use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet}; use crate::{Segment, UseError}; #[cfg(test)] mod tests; type Res = def::Res; /// A vector of spans and replacements, a message and applicability. pub(crate) type Suggestion = (Vec<(Span, String)>, String, Applicability); /// Potential candidate for an undeclared or out-of-scope label - contains the ident of a /// similarly named label and whether or not it is reachable. pub(crate) type LabelSuggestion = (Ident, bool); pub(crate) enum SuggestionTarget { /// The target has a similar name as the name used by the programmer (probably a typo) SimilarlyNamed, /// The target is the only valid item that can be used in the corresponding context SingleItem, } pub(crate) struct TypoSuggestion { pub candidate: Symbol, pub res: Res, pub target: SuggestionTarget, } impl TypoSuggestion { pub(crate) fn typo_from_res(candidate: Symbol, res: Res) -> TypoSuggestion { Self { candidate, res, target: SuggestionTarget::SimilarlyNamed } } pub(crate) fn single_item_from_res(candidate: Symbol, res: Res) -> TypoSuggestion { Self { candidate, res, target: SuggestionTarget::SingleItem } } } /// A free importable items suggested in case of resolution failure. pub(crate) struct ImportSuggestion { pub did: Option, pub descr: &'static str, pub path: Path, pub accessible: bool, /// An extra note that should be issued if this item is suggested pub note: Option, } /// 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(sm: &SourceMap, impl_span: Span) -> Span { let impl_span = sm.span_until_char(impl_span, '<'); sm.span_until_whitespace(impl_span) } impl<'a> Resolver<'a> { pub(crate) fn report_errors(&mut self, krate: &Crate) { self.report_with_use_injections(krate); for &(span_use, span_def) in &self.macro_expanded_macro_export_errors { let msg = "macro-expanded `macro_export` macros from the current crate \ cannot be referred to by absolute paths"; self.lint_buffer.buffer_lint_with_diagnostic( MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS, CRATE_NODE_ID, span_use, msg, BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def), ); } for ambiguity_error in &self.ambiguity_errors { self.report_ambiguity_error(ambiguity_error); } let mut reported_spans = FxHashSet::default(); for error in &self.privacy_errors { if reported_spans.insert(error.dedup_span) { self.report_privacy_error(error); } } } fn report_with_use_injections(&mut self, krate: &Crate) { for UseError { mut err, candidates, def_id, instead, suggestion, path } in self.use_injections.drain(..) { let (span, found_use) = if let Some(def_id) = def_id.as_local() { UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id]) } else { (None, FoundUse::No) }; if !candidates.is_empty() { show_candidates( &self.session, &self.source_span, &mut err, span, &candidates, if instead { Instead::Yes } else { Instead::No }, found_use, IsPattern::No, path, ); } else if let Some((span, msg, sugg, appl)) = suggestion { err.span_suggestion(span, msg, sugg, appl); } err.emit(); } } pub(crate) fn report_conflict<'b>( &mut self, parent: Module<'_>, ident: Ident, ns: Namespace, new_binding: &NameBinding<'b>, old_binding: &NameBinding<'b>, ) { // Error on the second of two conflicting names if old_binding.span.lo() > new_binding.span.lo() { return self.report_conflict(parent, ident, ns, old_binding, new_binding); } let container = match parent.kind { ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()), ModuleKind::Block => "block", }; let old_noun = match old_binding.is_import() { true => "import", false => "definition", }; let new_participle = match new_binding.is_import() { true => "imported", false => "defined", }; let (name, span) = (ident.name, self.session.source_map().guess_head_span(new_binding.span)); if let Some(s) = self.name_already_seen.get(&name) { if s == &span { return; } } let old_kind = match (ns, old_binding.module()) { (ValueNS, _) => "value", (MacroNS, _) => "macro", (TypeNS, _) if old_binding.is_extern_crate() => "extern crate", (TypeNS, Some(module)) if module.is_normal() => "module", (TypeNS, Some(module)) if module.is_trait() => "trait", (TypeNS, _) => "type", }; let msg = format!("the name `{}` is defined multiple times", name); let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) { (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg), (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() { true => struct_span_err!(self.session, span, E0254, "{}", msg), false => struct_span_err!(self.session, span, E0260, "{}", msg), }, _ => match (old_binding.is_import(), new_binding.is_import()) { (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg), (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg), _ => struct_span_err!(self.session, span, E0255, "{}", msg), }, }; err.note(&format!( "`{}` must be defined only once in the {} namespace of this {}", name, ns.descr(), container )); err.span_label(span, format!("`{}` re{} here", name, new_participle)); err.span_label( self.session.source_map().guess_head_span(old_binding.span), format!("previous {} of the {} `{}` here", old_noun, old_kind, name), ); // See https://github.com/rust-lang/rust/issues/32354 use NameBindingKind::Import; let import = match (&new_binding.kind, &old_binding.kind) { // If there are two imports where one or both have attributes then prefer removing the // import without attributes. (Import { import: new, .. }, Import { import: old, .. }) if { !new_binding.span.is_dummy() && !old_binding.span.is_dummy() && (new.has_attributes || old.has_attributes) } => { if old.has_attributes { Some((new, new_binding.span, true)) } else { Some((old, old_binding.span, true)) } } // Otherwise prioritize the new binding. (Import { import, .. }, other) if !new_binding.span.is_dummy() => { Some((import, new_binding.span, other.is_import())) } (other, Import { import, .. }) if !old_binding.span.is_dummy() => { Some((import, old_binding.span, other.is_import())) } _ => None, }; // Check if the target of the use for both bindings is the same. let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id(); let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy(); let from_item = self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item); // Only suggest removing an import if both bindings are to the same def, if both spans // aren't dummy spans. Further, if both bindings are imports, then the ident must have // been introduced by an item. let should_remove_import = duplicate && !has_dummy_span && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item); match import { Some((import, span, true)) if should_remove_import && import.is_nested() => { self.add_suggestion_for_duplicate_nested_use(&mut err, import, span) } Some((import, _, true)) if should_remove_import && !import.is_glob() => { // Simple case - remove the entire import. Due to the above match arm, this can // only be a single use so just remove it entirely. err.tool_only_span_suggestion( import.use_span_with_attributes, "remove unnecessary import", "", Applicability::MaybeIncorrect, ); } Some((import, span, _)) => { self.add_suggestion_for_rename_of_use(&mut err, name, import, span) } _ => {} } err.emit(); self.name_already_seen.insert(name, span); } /// This function adds a suggestion to change the binding name of a new import that conflicts /// with an existing import. /// /// ```text,ignore (diagnostic) /// help: you can use `as` to change the binding name of the import /// | /// LL | use foo::bar as other_bar; /// | ^^^^^^^^^^^^^^^^^^^^^ /// ``` fn add_suggestion_for_rename_of_use( &self, err: &mut Diagnostic, name: Symbol, import: &Import<'_>, binding_span: Span, ) { let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() { format!("Other{}", name) } else { format!("other_{}", name) }; let mut suggestion = None; match import.kind { ImportKind::Single { type_ns_only: true, .. } => { suggestion = Some(format!("self as {}", suggested_name)) } ImportKind::Single { source, .. } => { if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize) { if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) { if pos <= snippet.len() { suggestion = Some(format!( "{} as {}{}", &snippet[..pos], suggested_name, if snippet.ends_with(';') { ";" } else { "" } )) } } } } ImportKind::ExternCrate { source, target } => { suggestion = Some(format!( "extern crate {} as {};", source.unwrap_or(target.name), suggested_name, )) } _ => unreachable!(), } let rename_msg = "you can use `as` to change the binding name of the import"; if let Some(suggestion) = suggestion { err.span_suggestion( binding_span, rename_msg, suggestion, Applicability::MaybeIncorrect, ); } else { err.span_label(binding_span, rename_msg); } } /// This function adds a suggestion to remove an unnecessary binding from an import that is /// nested. In the following example, this function will be invoked to remove the `a` binding /// in the second use statement: /// /// ```ignore (diagnostic) /// use issue_52891::a; /// use issue_52891::{d, a, e}; /// ``` /// /// The following suggestion will be added: /// /// ```ignore (diagnostic) /// use issue_52891::{d, a, e}; /// ^-- help: remove unnecessary import /// ``` /// /// If the nested use contains only one import then the suggestion will remove the entire /// line. /// /// It is expected that the provided import is nested - this isn't checked by the /// function. If this invariant is not upheld, this function's behaviour will be unexpected /// as characters expected by span manipulations won't be present. fn add_suggestion_for_duplicate_nested_use( &self, err: &mut Diagnostic, import: &Import<'_>, binding_span: Span, ) { assert!(import.is_nested()); let message = "remove unnecessary import"; // Two examples will be used to illustrate the span manipulations we're doing: // // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is // `a` and `import.use_span` is `issue_52891::{d, a, e};`. // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is // `a` and `import.use_span` is `issue_52891::{d, e, a};`. let (found_closing_brace, span) = find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span); // If there was a closing brace then identify the span to remove any trailing commas from // previous imports. if found_closing_brace { if let Some(span) = extend_span_to_previous_binding(self.session, span) { err.tool_only_span_suggestion(span, message, "", Applicability::MaybeIncorrect); } else { // Remove the entire line if we cannot extend the span back, this indicates an // `issue_52891::{self}` case. err.span_suggestion( import.use_span_with_attributes, message, "", Applicability::MaybeIncorrect, ); } return; } err.span_suggestion(span, message, "", Applicability::MachineApplicable); } pub(crate) fn lint_if_path_starts_with_module( &mut self, finalize: Option, path: &[Segment], second_binding: Option<&NameBinding<'_>>, ) { let Some(Finalize { node_id, root_span, .. }) = finalize else { return; }; let first_name = match path.get(0) { // In the 2018 edition this lint is a hard error, so nothing to do Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name, _ => return, }; // We're only interested in `use` paths which should start with // `{{root}}` currently. if first_name != kw::PathRoot { return; } match path.get(1) { // If this import looks like `crate::...` it's already good Some(Segment { ident, .. }) if ident.name == kw::Crate => return, // Otherwise go below to see if it's an extern crate Some(_) => {} // If the path has length one (and it's `PathRoot` most likely) // then we don't know whether we're gonna be importing a crate or an // item in our crate. Defer this lint to elsewhere None => return, } // If the first element of our path was actually resolved to an // `ExternCrate` (also used for `crate::...`) then no need to issue a // warning, this looks all good! if let Some(binding) = second_binding { if let NameBindingKind::Import { import, .. } = binding.kind { // Careful: we still want to rewrite paths from renamed extern crates. if let ImportKind::ExternCrate { source: None, .. } = import.kind { return; } } } let diag = BuiltinLintDiagnostics::AbsPathWithModule(root_span); self.lint_buffer.buffer_lint_with_diagnostic( ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE, node_id, root_span, "absolute paths must start with `self`, `super`, \ `crate`, or an external crate name in the 2018 edition", diag, ); } pub(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::typo_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. pub(crate) fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) { self.into_struct_error(span, resolution_error).emit(); } pub(crate) fn into_struct_error( &mut self, span: Span, resolution_error: ResolutionError<'a>, ) -> DiagnosticBuilder<'_, ErrorGuaranteed> { 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, "use of generic parameter from outer function"); let sm = self.session.source_map(); let def_id = match outer_res { Res::SelfTy { trait_: maybe_trait_defid, alias_to: maybe_impl_defid } => { if let Some(impl_span) = maybe_impl_defid.and_then(|(def_id, _)| self.opt_span(def_id)) { err.span_label( reduce_impl_span_to_impl_keyword(sm, 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.opt_span(def_id) { err.span_label(span, "type parameter from outer function"); } def_id } Res::Def(DefKind::ConstParam, def_id) => { if let Some(span) = self.opt_span(def_id) { err.span_label(span, "const parameter from outer function"); } def_id } _ => { bug!( "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \ DefKind::TyParam or DefKind::ConstParam" ); } }; if let HasGenericParams::Yes(span) = has_generic_params { // Try to retrieve the span of the function signature and generate a new // message with a local type or const parameter. let sugg_msg = "try using a local generic parameter instead"; let name = self.opt_name(def_id).unwrap_or(sym::T); let (span, snippet) = if span.is_empty() { let snippet = format!("<{}>", name); (span, snippet) } else { let span = sm.span_through_char(span, '<').shrink_to_hi(); let snippet = format!("{}, ", name); (span, snippet) }; // Suggest the modification to the user err.span_suggestion(span, sugg_msg, snippet, Applicability::MaybeIncorrect); } 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_, candidate) => { 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_)); if let Some(candidate) = candidate { err.span_suggestion( method.span, "there is an associated function with a similar name", candidate.to_ident_string(), Applicability::MaybeIncorrect, ); } err } ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => { 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_)); if let Some(candidate) = candidate { err.span_suggestion( type_.span, "there is an associated type with a similar name", candidate.to_ident_string(), Applicability::MaybeIncorrect, ); } err } ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => { 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_)); if let Some(candidate) = candidate { err.span_suggestion( const_.span, "there is an associated constant with a similar name", candidate.to_ident_string(), Applicability::MaybeIncorrect, ); } err } ResolutionError::VariableNotBoundInPattern(binding_error, parent_scope) => { 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 import_suggestions = self.lookup_import_candidates( Ident::with_dummy_span(name), Namespace::ValueNS, &parent_scope, &|res: Res| match res { Res::Def( DefKind::Ctor(CtorOf::Variant, CtorKind::Const) | DefKind::Ctor(CtorOf::Struct, CtorKind::Const) | DefKind::Const | DefKind::AssocConst, _, ) => true, _ => false, }, ); if import_suggestions.is_empty() { let help_msg = format!( "if you meant to match on a variant or a `const` item, consider \ making the path in the pattern qualified: `path::to::ModOrType::{}`", name, ); err.span_help(span, &help_msg); } show_candidates( &self.session, &self.source_span, &mut err, Some(span), &import_suggestions, Instead::No, FoundUse::Yes, IsPattern::Yes, vec![], ); } err } ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => { let mut err = struct_span_err!( self.session, span, E0409, "variable `{}` is bound inconsistently across alternatives separated by `|`", 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, suggestion } => { let mut err = struct_span_err!( self.session, span, E0426, "use of undeclared label `{}`", name ); err.span_label(span, format!("undeclared label `{}`", name)); match suggestion { // A reachable label with a similar name exists. Some((ident, true)) => { err.span_label(ident.span, "a label with a similar name is reachable"); err.span_suggestion( span, "try using similarly named label", ident.name, Applicability::MaybeIncorrect, ); } // An unreachable label with a similar name exists. Some((ident, false)) => { err.span_label( ident.span, "a label with a similar name exists but is unreachable", ); } // No similarly-named labels exist. None => (), } err } ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => { let mut err = struct_span_err!( self.session, span, E0429, "{}", "`self` imports are only allowed within a { } list" ); // None of the suggestions below would help with a case like `use self`. if !root { // use foo::bar::self -> foo::bar // use foo::bar::self as abc -> foo::bar as abc err.span_suggestion( span, "consider importing the module directly", "", Applicability::MachineApplicable, ); // use foo::bar::self -> foo::bar::{self} // use foo::bar::self as abc -> foo::bar::{self as abc} let braces = vec![ (span_with_rename.shrink_to_lo(), "{".to_string()), (span_with_rename.shrink_to_hi(), "}".to_string()), ]; err.multipart_suggestion( "alternatively, use the multi-path `use` syntax to import `self`", braces, Applicability::MachineApplicable, ); } err } 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 { if suggestions.is_empty() { err.help(&msg); return err; } 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(ident, sugg, current) => { let mut err = struct_span_err!( self.session, span, E0435, "attempt to use a non-constant value in a constant" ); // let foo =... // ^^^ given this Span // ------- get this Span to have an applicable suggestion // edit: // only do this if the const and usage of the non-constant value are on the same line // the further the two are apart, the higher the chance of the suggestion being wrong let sp = self .session .source_map() .span_extend_to_prev_str(ident.span, current, true, false); match sp { Some(sp) if !self.session.source_map().is_multiline(sp) => { let sp = sp.with_lo(BytePos(sp.lo().0 - (current.len() as u32))); err.span_suggestion( sp, &format!("consider using `{}` instead of `{}`", sugg, current), format!("{} {}", sugg, ident), Applicability::MaybeIncorrect, ); err.span_label(span, "non-constant value"); } _ => { err.span_label(ident.span, &format!("this would need to be a `{}`", sugg)); } } err } ResolutionError::BindingShadowsSomethingUnacceptable { shadowing_binding, name, participle, article, shadowed_binding, shadowed_binding_span, } => { let shadowed_binding_descr = shadowed_binding.descr(); let mut err = struct_span_err!( self.session, span, E0530, "{}s cannot shadow {}s", shadowing_binding.descr(), shadowed_binding_descr, ); err.span_label( span, format!("cannot be named the same as {} {}", article, shadowed_binding_descr), ); match (shadowing_binding, shadowed_binding) { ( PatternSource::Match, Res::Def(DefKind::Ctor(CtorOf::Variant | CtorOf::Struct, CtorKind::Fn), _), ) => { err.span_suggestion( span, "try specify the pattern arguments", format!("{}(..)", name), Applicability::Unspecified, ); } _ => (), } let msg = format!("the {} `{}` is {} here", shadowed_binding_descr, name, participle); err.span_label(shadowed_binding_span, msg); err } ResolutionError::ForwardDeclaredGenericParam => { let mut err = struct_span_err!( self.session, span, E0128, "generic parameters with a default cannot use \ forward declared identifiers" ); err.span_label(span, "defaulted generic parameters cannot be forward declared"); err } ResolutionError::ParamInTyOfConstParam(name) => { let mut err = struct_span_err!( self.session, span, E0770, "the type of const parameters must not depend on other generic parameters" ); err.span_label( span, format!("the type must not depend on the parameter `{}`", name), ); err } ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => { let mut err = self.session.struct_span_err( span, "generic parameters may not be used in const operations", ); err.span_label(span, &format!("cannot perform const operation using `{}`", name)); if is_type { err.note("type parameters may not be used in const expressions"); } else { err.help(&format!( "const parameters may only be used as standalone arguments, i.e. `{}`", name )); } if self.session.is_nightly_build() { err.help( "use `#![feature(generic_const_exprs)]` to allow generic const expressions", ); } err } ResolutionError::SelfInGenericParamDefault => { let mut err = struct_span_err!( self.session, span, E0735, "generic parameters cannot use `Self` in their defaults" ); err.span_label(span, "`Self` in generic parameter default"); err } ResolutionError::UnreachableLabel { name, definition_span, suggestion } => { let mut err = struct_span_err!( self.session, span, E0767, "use of unreachable label `{}`", name, ); err.span_label(definition_span, "unreachable label defined here"); err.span_label(span, format!("unreachable label `{}`", name)); err.note( "labels are unreachable through functions, closures, async blocks and modules", ); match suggestion { // A reachable label with a similar name exists. Some((ident, true)) => { err.span_label(ident.span, "a label with a similar name is reachable"); err.span_suggestion( span, "try using similarly named label", ident.name, Applicability::MaybeIncorrect, ); } // An unreachable label with a similar name exists. Some((ident, false)) => { err.span_label( ident.span, "a label with a similar name exists but is also unreachable", ); } // No similarly-named labels exist. None => (), } err } ResolutionError::TraitImplMismatch { name, kind, code, trait_item_span, trait_path, } => { let mut err = self.session.struct_span_err_with_code( span, &format!( "item `{}` is an associated {}, which doesn't match its trait `{}`", name, kind, trait_path, ), code, ); err.span_label(span, "does not match trait"); err.span_label(trait_item_span, "item in trait"); err } ResolutionError::InvalidAsmSym => { let mut err = self.session.struct_span_err(span, "invalid `sym` operand"); err.span_label(span, "is a local variable"); err.help("`sym` operands must refer to either a function or a static"); err } } } pub(crate) fn report_vis_error( &mut self, vis_resolution_error: VisResolutionError<'_>, ) -> ErrorGuaranteed { match vis_resolution_error { VisResolutionError::Relative2018(span, path) => { let mut err = self.session.struct_span_err( span, "relative paths are not supported in visibilities in 2018 edition or later", ); 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<'a>, parent_scope: &ParentScope<'a>, ident: Ident, filter_fn: &impl Fn(Res) -> bool, ) -> Option { let mut suggestions = Vec::new(); let ctxt = ident.span.ctxt(); self.visit_scopes(scope_set, parent_scope, ctxt, |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::typo_from_res(ident.name, res)), ); } } Scope::DeriveHelpersCompat => { let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat); 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::typo_from_res(*name, res)), ); } } } } Scope::MacroRules(macro_rules_scope) => { if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() { let res = macro_rules_binding.binding.res(); if filter_fn(res) { suggestions.push(TypoSuggestion::typo_from_res( macro_rules_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::MacroUsePrelude => { suggestions.extend(this.macro_use_prelude.iter().filter_map( |(name, binding)| { let res = binding.res(); filter_fn(res).then_some(TypoSuggestion::typo_from_res(*name, res)) }, )); } Scope::BuiltinAttrs => { let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin(kw::Empty)); if filter_fn(res) { suggestions.extend( BUILTIN_ATTRIBUTES .iter() .map(|attr| TypoSuggestion::typo_from_res(attr.name, res)), ); } } Scope::ExternPrelude => { suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| { let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()); filter_fn(res).then_some(TypoSuggestion::typo_from_res(ident.name, res)) })); } Scope::ToolPrelude => { let res = Res::NonMacroAttr(NonMacroAttrKind::Tool); suggestions.extend( this.registered_tools .iter() .map(|ident| TypoSuggestion::typo_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 => { suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| { let res = Res::PrimTy(*prim_ty); filter_fn(res).then_some(TypoSuggestion::typo_from_res(prim_ty.name(), res)) })) } } None::<()> }); // Make sure error reporting is deterministic. suggestions.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap()); match find_best_match_for_name( &suggestions.iter().map(|suggestion| suggestion.candidate).collect::>(), ident.name, 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, parent_scope: &ParentScope<'a>, 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 mut worklist = vec![(start_module, Vec::::new(), true)]; let mut worklist_via_import = vec![]; while let Some((in_module, path_segments, accessible)) = match worklist.pop() { None => worklist_via_import.pop(), Some(x) => Some(x), } { let in_module_is_extern = !in_module.def_id().is_local(); // 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 non-importable candidates if !name_binding.is_importable() { return; } let child_accessible = accessible && this.is_accessible_from(name_binding.vis, parent_scope.module); // do not venture inside inaccessible items of other crates if in_module_is_extern && !child_accessible { return; } let via_import = name_binding.is_import() && !name_binding.is_extern_crate(); // There is an assumption elsewhere that paths of variants are in the enum's // declaration and not imported. With this assumption, the variant component is // chopped and the rest of the path is assumed to be the enum's own path. For // errors where a variant is used as the type instead of the enum, this causes // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`. if via_import && name_binding.is_possibly_imported_variant() { return; } // #90113: Do not count an inaccessible reexported item as a candidate. if let NameBindingKind::Import { binding, .. } = name_binding.kind { if this.is_accessible_from(binding.vis, parent_scope.module) && !this.is_accessible_from(name_binding.vis, parent_scope.module) { return; } } // collect results based on the filter function // avoid suggesting anything from the same module in which we are resolving // avoid suggesting anything with a hygienic name if ident.name == lookup_ident.name && ns == namespace && !ptr::eq(in_module, parent_scope.module) && !ident.span.normalize_to_macros_2_0().from_expansion() { 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, tokens: None }; let did = match res { Res::Def(DefKind::Ctor(..), did) => this.opt_parent(did), _ => res.opt_def_id(), }; if child_accessible { // Remove invisible match if exists if let Some(idx) = candidates .iter() .position(|v: &ImportSuggestion| v.did == did && !v.accessible) { candidates.remove(idx); } } if candidates.iter().all(|v: &ImportSuggestion| v.did != did) { // See if we're recommending TryFrom, TryInto, or FromIterator and add // a note about editions let note = if let Some(did) = did { let requires_note = !did.is_local() && this.cstore().item_attrs_untracked(did, this.session).any( |attr| { if attr.has_name(sym::rustc_diagnostic_item) { [sym::TryInto, sym::TryFrom, sym::FromIterator] .map(|x| Some(x)) .contains(&attr.value_str()) } else { false } }, ); requires_note.then(|| { format!( "'{}' is included in the prelude starting in Edition 2021", path_names_to_string(&path) ) }) } else { None }; candidates.push(ImportSuggestion { did, descr: res.descr(), path, accessible: child_accessible, note, }); } } } // 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(); if !is_extern_crate_that_also_appears_in_prelude { // add the module to the lookup if seen_modules.insert(module.def_id()) { if via_import { &mut worklist_via_import } else { &mut worklist } .push((module, path_segments, child_accessible)); } } } }) } // If only some candidates are accessible, take just them if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) { candidates.retain(|x| x.accessible) } 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). pub(crate) fn lookup_import_candidates( &mut self, lookup_ident: Ident, namespace: Namespace, parent_scope: &ParentScope<'a>, filter_fn: FilterFn, ) -> Vec where FilterFn: Fn(Res) -> bool, { let mut suggestions = self.lookup_import_candidates_from_module( lookup_ident, namespace, parent_scope, 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) { let crate_root = self.expect_module(crate_id.as_def_id()); suggestions.extend(self.lookup_import_candidates_from_module( lookup_ident, namespace, parent_scope, crate_root, ident, &filter_fn, )); } } } suggestions } pub(crate) fn unresolved_macro_suggestions( &mut self, err: &mut Diagnostic, 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); let import_suggestions = self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected); show_candidates( &self.session, &self.source_span, err, None, &import_suggestions, Instead::No, FoundUse::Yes, IsPattern::No, vec![], ); if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) { let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident); err.span_note(ident.span, &msg); return; } if self.macro_names.contains(&ident.normalize_to_macros_2_0()) { err.help("have you added the `#[macro_use]` on the module/import?"); return; } if ident.name == kw::Default && let ModuleKind::Def(DefKind::Enum, def_id, _) = parent_scope.module.kind && let Some(span) = self.opt_span(def_id) { let source_map = self.session.source_map(); let head_span = source_map.guess_head_span(span); if let Ok(head) = source_map.span_to_snippet(head_span) { err.span_suggestion(head_span, "consider adding a derive", format!("#[derive(Default)]\n{head}"), Applicability::MaybeIncorrect); } else { err.span_help( head_span, "consider adding `#[derive(Default)]` to this enum", ); } } for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] { if let Ok(binding) = self.early_resolve_ident_in_lexical_scope( ident, ScopeSet::All(ns, false), &parent_scope, None, false, None, ) { let desc = match binding.res() { Res::Def(DefKind::Macro(MacroKind::Bang), _) => { "a function-like macro".to_string() } Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => { format!("an attribute: `#[{}]`", ident) } Res::Def(DefKind::Macro(MacroKind::Derive), _) => { format!("a derive macro: `#[derive({})]`", ident) } Res::ToolMod => { // Don't confuse the user with tool modules. continue; } Res::Def(DefKind::Trait, _) if macro_kind == MacroKind::Derive => { "only a trait, without a derive macro".to_string() } res => format!( "{} {}, not {} {}", res.article(), res.descr(), macro_kind.article(), macro_kind.descr_expected(), ), }; if let crate::NameBindingKind::Import { import, .. } = binding.kind { if !import.span.is_dummy() { err.span_note( import.span, &format!("`{}` is imported here, but it is {}", ident, desc), ); // Silence the 'unused import' warning we might get, // since this diagnostic already covers that import. self.record_use(ident, binding, false); return; } } err.note(&format!("`{}` is in scope, but it is {}", ident, desc)); return; } } } pub(crate) fn add_typo_suggestion( &self, err: &mut Diagnostic, suggestion: Option, span: Span, ) -> bool { let suggestion = match suggestion { None => return false, // We shouldn't suggest underscore. Some(suggestion) if suggestion.candidate == kw::Underscore => return false, Some(suggestion) => suggestion, }; let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate { LOCAL_CRATE => self.opt_span(def_id), _ => Some(self.cstore().get_span_untracked(def_id, self.session)), }); if let Some(def_span) = def_span { if span.overlaps(def_span) { // Don't suggest typo suggestion for itself like in the following: // error[E0423]: expected function, tuple struct or tuple variant, found struct `X` // --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14 // | // LL | struct X {} // | ----------- `X` defined here // LL | // LL | const Y: X = X("ö"); // | -------------^^^^^^- similarly named constant `Y` defined here // | // help: use struct literal syntax instead // | // LL | const Y: X = X {}; // | ^^^^ // help: a constant with a similar name exists // | // LL | const Y: X = Y("ö"); // | ^ return false; } let prefix = match suggestion.target { SuggestionTarget::SimilarlyNamed => "similarly named ", SuggestionTarget::SingleItem => "", }; err.span_label( self.session.source_map().guess_head_span(def_span), &format!( "{}{} `{}` defined here", prefix, suggestion.res.descr(), suggestion.candidate, ), ); } let msg = match suggestion.target { SuggestionTarget::SimilarlyNamed => format!( "{} {} with a similar name exists", suggestion.res.article(), suggestion.res.descr() ), SuggestionTarget::SingleItem => { format!("maybe you meant this {}", suggestion.res.descr()) } }; err.span_suggestion(span, &msg, suggestion.candidate, Applicability::MaybeIncorrect); true } fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String { let res = b.res(); if b.span.is_dummy() || !self.session.source_map().is_span_accessible(b.span) { // These already contain the "built-in" prefix or look bad with it. let add_built_in = !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod); 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 a = if built_in.is_empty() { res.article() } else { "a" }; format!("{a}{built_in} {thing}{from}", thing = res.descr()) } else { let introduced = if b.is_import() { "imported" } else { "defined" }; format!("the {thing} {introduced} here", thing = res.descr()) } } 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"); err.span_label(ident.span, "ambiguous name"); err.note(&format!("ambiguous because of {}", kind.descr())); 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}"); 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" )) } if b.is_extern_crate() && ident.span.rust_2018() { help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously")) } if misc == AmbiguityErrorMisc::SuggestCrate { help_msgs .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously")) } else if misc == AmbiguityErrorMisc::SuggestSelf { help_msgs .push(format!("use `self::{ident}` to refer to this {thing} unambiguously")) } 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(); } /// If the binding refers to a tuple struct constructor with fields, /// returns the span of its fields. fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option { 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); let fields = self.field_names.get(&def_id)?; return fields.iter().map(|name| name.span).reduce(Span::to); // None for `struct Foo()` } None } fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) { let PrivacyError { ident, binding, .. } = *privacy_error; let res = binding.res(); let ctor_fields_span = self.ctor_fields_span(binding); let plain_descr = res.descr().to_string(); let nonimport_descr = if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr }; let import_descr = nonimport_descr.clone() + " import"; let get_descr = |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr }; // Print the primary message. let descr = get_descr(binding); let mut err = struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident); err.span_label(ident.span, &format!("private {}", descr)); if let Some(span) = ctor_fields_span { err.span_label(span, "a constructor is private if any of the fields is private"); } // Print the whole import chain to make it easier to see what happens. let first_binding = binding; let mut next_binding = Some(binding); let mut next_ident = ident; while let Some(binding) = next_binding { let name = next_ident; next_binding = match binding.kind { _ if res == Res::Err => None, NameBindingKind::Import { binding, import, .. } => match import.kind { _ if binding.span.is_dummy() => None, ImportKind::Single { source, .. } => { next_ident = source; Some(binding) } ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding), ImportKind::ExternCrate { .. } => None, }, _ => None, }; let first = ptr::eq(binding, first_binding); let msg = format!( "{and_refers_to}the {item} `{name}`{which} is defined here{dots}", and_refers_to = if first { "" } else { "...and refers to " }, item = get_descr(binding), which = if first { "" } else { " which" }, dots = if next_binding.is_some() { "..." } else { "" }, ); let def_span = self.session.source_map().guess_head_span(binding.span); let mut note_span = MultiSpan::from_span(def_span); if !first && binding.vis.is_public() { note_span.push_span_label(def_span, "consider importing it directly"); } err.span_note(note_span, &msg); } err.emit(); } pub(crate) fn find_similarly_named_module_or_crate( &mut self, ident: Symbol, current_module: &Module<'a>, ) -> Option { let mut candidates = self .extern_prelude .iter() .map(|(ident, _)| ident.name) .chain( self.module_map .iter() .filter(|(_, module)| { current_module.is_ancestor_of(module) && !ptr::eq(current_module, *module) }) .flat_map(|(_, module)| module.kind.name()), ) .filter(|c| !c.to_string().is_empty()) .collect::>(); candidates.sort(); candidates.dedup(); match find_best_match_for_name(&candidates, ident, None) { Some(sugg) if sugg == ident => None, sugg => sugg, } } pub(crate) fn report_path_resolution_error( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, ribs: Option<&PerNS>>>, ignore_binding: Option<&'a NameBinding<'a>>, module: Option>, i: usize, ident: Ident, ) -> (String, Option) { let is_last = i == path.len() - 1; let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS }; let module_res = match module { Some(ModuleOrUniformRoot::Module(module)) => module.res(), _ => None, }; if module_res == self.graph_root.res() { let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _)); let mut candidates = self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod); candidates .sort_by_cached_key(|c| (c.path.segments.len(), pprust::path_to_string(&c.path))); if let Some(candidate) = candidates.get(0) { ( String::from("unresolved import"), Some(( vec![(ident.span, pprust::path_to_string(&candidate.path))], String::from("a similar path exists"), Applicability::MaybeIncorrect, )), ) } else if self.session.edition() == Edition::Edition2015 { ( format!("maybe a missing crate `{ident}`?"), Some(( vec![], format!( "consider adding `extern crate {ident}` to use the `{ident}` crate" ), Applicability::MaybeIncorrect, )), ) } else { (format!("could not find `{ident}` in the crate root"), None) } } else if i > 0 { let parent = path[i - 1].ident.name; let parent = match parent { // ::foo is mounted at the crate root for 2015, and is the extern // prelude for 2018+ kw::PathRoot if self.session.edition() > Edition::Edition2015 => { "the list of imported crates".to_owned() } kw::PathRoot | kw::Crate => "the crate root".to_owned(), _ => format!("`{parent}`"), }; let mut msg = format!("could not find `{}` in {}", ident, parent); if ns == TypeNS || ns == ValueNS { let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS }; let binding = if let Some(module) = module { self.resolve_ident_in_module( module, ident, ns_to_try, parent_scope, None, ignore_binding, ).ok() } else if let Some(ribs) = ribs && let Some(TypeNS | ValueNS) = opt_ns { match self.resolve_ident_in_lexical_scope( ident, ns_to_try, parent_scope, None, &ribs[ns_to_try], ignore_binding, ) { // we found a locally-imported or available item/module Some(LexicalScopeBinding::Item(binding)) => Some(binding), _ => None, } } else { let scopes = ScopeSet::All(ns_to_try, opt_ns.is_none()); self.early_resolve_ident_in_lexical_scope( ident, scopes, parent_scope, None, false, ignore_binding, ).ok() }; if let Some(binding) = binding { let mut found = |what| { msg = format!( "expected {}, found {} `{}` in {}", ns.descr(), what, ident, parent ) }; if binding.module().is_some() { found("module") } else { match binding.res() { Res::Def(kind, id) => found(kind.descr(id)), _ => found(ns_to_try.descr()), } } }; } (msg, None) } else if ident.name == kw::SelfUpper { ("`Self` is only available in impls, traits, and type definitions".to_string(), None) } else if ident.name.as_str().chars().next().map_or(false, |c| c.is_ascii_uppercase()) { // Check whether the name refers to an item in the value namespace. let binding = if let Some(ribs) = ribs { self.resolve_ident_in_lexical_scope( ident, ValueNS, parent_scope, None, &ribs[ValueNS], ignore_binding, ) } else { None }; let match_span = match binding { // Name matches a local variable. For example: // ``` // fn f() { // let Foo: &str = ""; // println!("{}", Foo::Bar); // Name refers to local // // variable `Foo`. // } // ``` Some(LexicalScopeBinding::Res(Res::Local(id))) => { Some(*self.pat_span_map.get(&id).unwrap()) } // Name matches item from a local name binding // created by `use` declaration. For example: // ``` // pub Foo: &str = ""; // // mod submod { // use super::Foo; // println!("{}", Foo::Bar); // Name refers to local // // binding `Foo`. // } // ``` Some(LexicalScopeBinding::Item(name_binding)) => Some(name_binding.span), _ => None, }; let suggestion = if let Some(span) = match_span { Some(( vec![(span, String::from(""))], format!("`{}` is defined here, but is not a type", ident), Applicability::MaybeIncorrect, )) } else { None }; (format!("use of undeclared type `{}`", ident), suggestion) } else { let suggestion = if ident.name == sym::alloc { Some(( vec![], String::from("add `extern crate alloc` to use the `alloc` crate"), Applicability::MaybeIncorrect, )) } else { self.find_similarly_named_module_or_crate(ident.name, &parent_scope.module).map( |sugg| { ( vec![(ident.span, sugg.to_string())], String::from("there is a crate or module with a similar name"), Applicability::MaybeIncorrect, ) }, ) }; (format!("use of undeclared crate or module `{}`", ident), suggestion) } } } 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, Option)> { 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::empty())); } _ => return None, } self.make_missing_self_suggestion(path.clone(), parent_scope) .or_else(|| self.make_missing_crate_suggestion(path.clone(), parent_scope)) .or_else(|| self.make_missing_super_suggestion(path.clone(), parent_scope)) .or_else(|| self.make_external_crate_suggestion(path, parent_scope)) } /// Suggest a missing `self::` if that resolves to an correct module. /// /// ```text /// | /// LL | use foo::Bar; /// | ^^^ did you mean `self::foo`? /// ``` fn make_missing_self_suggestion( &mut self, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `self` and check if that is valid. path[0].ident.name = kw::SelfLower; let result = self.r.maybe_resolve_path(&path, None, parent_scope); debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, None)) } else { None } } /// Suggests a missing `crate::` if that resolves to an correct module. /// /// ```text /// | /// LL | use foo::Bar; /// | ^^^ did you mean `crate::foo`? /// ``` fn make_missing_crate_suggestion( &mut self, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = kw::Crate; let result = self.r.maybe_resolve_path(&path, None, parent_scope); debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some(( path, Some( "`use` statements changed in Rust 2018; read more at \ " .to_string(), ), )) } else { None } } /// Suggests a missing `super::` if that resolves to an correct module. /// /// ```text /// | /// LL | use foo::Bar; /// | ^^^ did you mean `super::foo`? /// ``` fn make_missing_super_suggestion( &mut self, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { // Replace first ident with `crate` and check if that is valid. path[0].ident.name = kw::Super; let result = self.r.maybe_resolve_path(&path, None, parent_scope); debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result); if let PathResult::Module(..) = result { Some((path, None)) } else { None } } /// Suggests a missing external crate name if that resolves to an correct module. /// /// ```text /// | /// 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, mut path: Vec, parent_scope: &ParentScope<'b>, ) -> Option<(Vec, Option)> { if path[1].ident.span.rust_2015() { return None; } // Sort extern crate names in *reverse* order to get // 1) some consistent ordering for emitted diagnostics, 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(|a, b| b.as_str().partial_cmp(a.as_str()).unwrap()); 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.maybe_resolve_path(&path, None, parent_scope); debug!( "make_external_crate_suggestion: name={:?} path={:?} result={:?}", name, path, result ); if let PathResult::Module(..) = result { return Some((path, None)); } } None } /// Suggests importing a macro from the root of the crate rather than a module within /// the crate. /// /// ```text /// 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, import: &'b Import<'b>, module: ModuleOrUniformRoot<'b>, ident: Ident, ) -> Option<(Option, Option)> { let ModuleOrUniformRoot::Module(mut crate_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_snippet = match import.kind { ImportKind::Single { source, target, .. } if source != target => { format!("{} as {}", source, target) } _ => format!("{}", ident), }; let mut corrections: Vec<(Span, String)> = Vec::new(); if !import.is_nested() { // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove // intermediate segments. corrections.push((import.span, format!("{}::{}", module_name, import_snippet))); } 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, import.span, import.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 immediately // 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, import.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_snippet) } else { // In this case, add a `{`, then the moved import, then whatever // was there before. format!("{{{}, {}", import_snippet, 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, )); Some((suggestion, Some("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()))) } else { None } } } /// Given a `binding_span` of a binding within a use statement: /// /// ```ignore (illustrative) /// use foo::{a, b, c}; /// // ^ /// ``` /// /// then return the span until the next binding or the end of the statement: /// /// ```ignore (illustrative) /// use foo::{a, b, c}; /// // ^^^ /// ``` 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. /// /// ```ignore (illustrative) /// use foo::a::{a, b, c}; /// // ^^--- binding span /// // | /// // returned span /// /// use foo::{a, b, c}; /// // --- binding span /// ``` 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. /// /// ```ignore (illustrative) /// 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; } !matches!(c, ':' if num_colons == 2) }); // 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) } /// A suggestion has already been emitted, change the wording slightly to clarify that both are /// independent options. enum Instead { Yes, No, } /// Whether an existing place with an `use` item was found. enum FoundUse { Yes, No, } /// Whether a binding is part of a pattern or an expression. Used for diagnostics. enum IsPattern { /// The binding is part of a pattern Yes, /// The binding is part of an expression No, } /// 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 fn show_candidates( session: &Session, source_span: &IndexVec, err: &mut Diagnostic, // This is `None` if all placement locations are inside expansions use_placement_span: Option, candidates: &[ImportSuggestion], instead: Instead, found_use: FoundUse, is_pattern: IsPattern, path: Vec, ) { if candidates.is_empty() { return; } let mut accessible_path_strings: Vec<(String, &str, Option, &Option)> = Vec::new(); let mut inaccessible_path_strings: Vec<(String, &str, Option, &Option)> = Vec::new(); candidates.iter().for_each(|c| { (if c.accessible { &mut accessible_path_strings } else { &mut inaccessible_path_strings }) .push((path_names_to_string(&c.path), c.descr, c.did, &c.note)) }); // we want consistent results across executions, but candidates are produced // by iterating through a hash map, so make sure they are ordered: for path_strings in [&mut accessible_path_strings, &mut inaccessible_path_strings] { path_strings.sort_by(|a, b| a.0.cmp(&b.0)); let core_path_strings = path_strings.drain_filter(|p| p.0.starts_with("core::")).collect::>(); path_strings.extend(core_path_strings); path_strings.dedup_by(|a, b| a.0 == b.0); } if !accessible_path_strings.is_empty() { let (determiner, kind, name) = if accessible_path_strings.len() == 1 { ("this", accessible_path_strings[0].1, format!(" `{}`", accessible_path_strings[0].0)) } else { ("one of these", "items", String::new()) }; let instead = if let Instead::Yes = instead { " instead" } else { "" }; let mut msg = if let IsPattern::Yes = is_pattern { format!( "if you meant to match on {}{}{}, use the full path in the pattern", kind, instead, name ) } else { format!("consider importing {} {}{}", determiner, kind, instead) }; for note in accessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) { err.note(note); } if let (IsPattern::Yes, Some(span)) = (is_pattern, use_placement_span) { err.span_suggestions( span, &msg, accessible_path_strings.into_iter().map(|a| a.0), Applicability::MaybeIncorrect, ); } else if let Some(span) = use_placement_span { for candidate in &mut accessible_path_strings { // produce an additional newline to separate the new use statement // from the directly following item. let additional_newline = if let FoundUse::Yes = found_use { "" } else { "\n" }; candidate.0 = format!("use {};\n{}", &candidate.0, additional_newline); } err.span_suggestions( span, &msg, accessible_path_strings.into_iter().map(|a| a.0), Applicability::MaybeIncorrect, ); if let [first, .., last] = &path[..] { let sp = first.ident.span.until(last.ident.span); if sp.can_be_used_for_suggestions() { err.span_suggestion_verbose( sp, &format!("if you import `{}`, refer to it directly", last.ident), "", Applicability::Unspecified, ); } } } else { msg.push(':'); for candidate in accessible_path_strings { msg.push('\n'); msg.push_str(&candidate.0); } err.note(&msg); } } else { assert!(!inaccessible_path_strings.is_empty()); let prefix = if let IsPattern::Yes = is_pattern { "you might have meant to match on " } else { "" }; if inaccessible_path_strings.len() == 1 { let (name, descr, def_id, note) = &inaccessible_path_strings[0]; let msg = format!( "{}{} `{}`{} exists but is inaccessible", prefix, descr, name, if let IsPattern::Yes = is_pattern { ", which" } else { "" } ); if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) { let span = source_span[local_def_id]; let span = session.source_map().guess_head_span(span); let mut multi_span = MultiSpan::from_span(span); multi_span.push_span_label(span, "not accessible"); err.span_note(multi_span, &msg); } else { err.note(&msg); } if let Some(note) = (*note).as_deref() { err.note(note); } } else { let (_, descr_first, _, _) = &inaccessible_path_strings[0]; let descr = if inaccessible_path_strings .iter() .skip(1) .all(|(_, descr, _, _)| descr == descr_first) { descr_first } else { "item" }; let plural_descr = if descr.ends_with('s') { format!("{}es", descr) } else { format!("{}s", descr) }; let mut msg = format!("{}these {} exist but are inaccessible", prefix, plural_descr); let mut has_colon = false; let mut spans = Vec::new(); for (name, _, def_id, _) in &inaccessible_path_strings { if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) { let span = source_span[local_def_id]; let span = session.source_map().guess_head_span(span); spans.push((name, span)); } else { if !has_colon { msg.push(':'); has_colon = true; } msg.push('\n'); msg.push_str(name); } } let mut multi_span = MultiSpan::from_spans(spans.iter().map(|(_, sp)| *sp).collect()); for (name, span) in spans { multi_span.push_span_label(span, format!("`{}`: not accessible", name)); } for note in inaccessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) { err.note(note); } err.span_note(multi_span, &msg); } } } #[derive(Debug)] struct UsePlacementFinder { target_module: NodeId, first_legal_span: Option, first_use_span: Option, } impl UsePlacementFinder { fn check(krate: &Crate, target_module: NodeId) -> (Option, FoundUse) { let mut finder = UsePlacementFinder { target_module, first_legal_span: None, first_use_span: None }; finder.visit_crate(krate); if let Some(use_span) = finder.first_use_span { (Some(use_span), FoundUse::Yes) } else { (finder.first_legal_span, FoundUse::No) } } } impl<'tcx> visit::Visitor<'tcx> for UsePlacementFinder { fn visit_crate(&mut self, c: &Crate) { if self.target_module == CRATE_NODE_ID { let inject = c.spans.inject_use_span; if is_span_suitable_for_use_injection(inject) { self.first_legal_span = Some(inject); } self.first_use_span = search_for_any_use_in_items(&c.items); return; } else { visit::walk_crate(self, c); } } fn visit_item(&mut self, item: &'tcx ast::Item) { if self.target_module == item.id { if let ItemKind::Mod(_, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind { let inject = mod_spans.inject_use_span; if is_span_suitable_for_use_injection(inject) { self.first_legal_span = Some(inject); } self.first_use_span = search_for_any_use_in_items(items); return; } } else { visit::walk_item(self, item); } } } fn search_for_any_use_in_items(items: &[P]) -> Option { for item in items { if let ItemKind::Use(..) = item.kind { if is_span_suitable_for_use_injection(item.span) { return Some(item.span.shrink_to_lo()); } } } return None; } fn is_span_suitable_for_use_injection(s: Span) -> bool { // don't suggest placing a use before the prelude // import or other generated ones !s.from_expansion() } /// Convert the given number into the corresponding ordinal pub(crate) fn ordinalize(v: usize) -> String { let suffix = match ((11..=13).contains(&(v % 100)), v % 10) { (false, 1) => "st", (false, 2) => "nd", (false, 3) => "rd", _ => "th", }; format!("{v}{suffix}") }