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Diffstat (limited to 'compiler/rustc_resolve/src/diagnostics.rs')
| -rw-r--r-- | compiler/rustc_resolve/src/diagnostics.rs | 2714 |
1 files changed, 2714 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs new file mode 100644 index 000000000..8839fb1a1 --- /dev/null +++ b/compiler/rustc_resolve/src/diagnostics.rs @@ -0,0 +1,2714 @@ +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 tracing::debug; + +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<ast::NodeId>; + +/// 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<DefId>, + 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<String>, +} + +/// Adjust the impl span so that just the `impl` keyword is taken by removing +/// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "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<Finalize>, + 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<TypoSuggestion>, + 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(); + 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"); + } + } + Res::Def(DefKind::ConstParam, def_id) => { + if let Some(span) = self.opt_span(def_id) { + err.span_label(span, "const parameter from outer function"); + } + } + _ => { + bug!( + "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \ + DefKind::TyParam or DefKind::ConstParam" + ); + } + } + + 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 = "try using a local generic parameter instead"; + if let Some((sugg_span, snippet)) = sm.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) = sm.generate_fn_name_span(span) { + err.span_label( + sp, + "try adding a local generic parameter in this method instead", + ); + } else { + err.help("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_, 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::<Vec<_>>(); + let origin_sp = origin.iter().copied().collect::<Vec<_>>(); + + 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<TypoSuggestion> { + 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::RegisteredAttrs => { + let res = Res::NonMacroAttr(NonMacroAttrKind::Registered); + if filter_fn(res) { + suggestions.extend( + this.registered_attrs + .iter() + .map(|ident| TypoSuggestion::typo_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::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::<Vec<Symbol>>(), + ident.name, + None, + ) { + Some(found) if found != ident.name => { + suggestions.into_iter().find(|suggestion| suggestion.candidate == found) + } + _ => None, + } + } + + fn lookup_import_candidates_from_module<FilterFn>( + &mut self, + lookup_ident: Ident, + namespace: Namespace, + parent_scope: &ParentScope<'a>, + start_module: Module<'a>, + crate_name: Ident, + filter_fn: FilterFn, + ) -> Vec<ImportSuggestion> + where + FilterFn: Fn(Res) -> bool, + { + let mut candidates = Vec::new(); + let mut seen_modules = FxHashSet::default(); + let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::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 = candidates.into_iter().filter(|x| x.accessible).collect(); + } + + 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<FilterFn>( + &mut self, + lookup_ident: Ident, + namespace: Namespace, + parent_scope: &ParentScope<'a>, + filter_fn: FilterFn, + ) -> Vec<ImportSuggestion> + 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<TypoSuggestion>, + 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<Span> { + 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<Symbol> { + 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::<Vec<_>>(); + 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<Namespace>, // `None` indicates a module path in import + parent_scope: &ParentScope<'a>, + ribs: Option<&PerNS<Vec<Rib<'a>>>>, + ignore_binding: Option<&'a NameBinding<'a>>, + module: Option<ModuleOrUniformRoot<'a>>, + i: usize, + ident: Ident, + ) -> (String, Option<Suggestion>) { + 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<Segment>, + parent_scope: &ParentScope<'b>, + ) -> Option<(Vec<Segment>, Option<String>)> { + 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<Segment>, + parent_scope: &ParentScope<'b>, + ) -> Option<(Vec<Segment>, Option<String>)> { + // 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<Segment>, + parent_scope: &ParentScope<'b>, + ) -> Option<(Vec<Segment>, Option<String>)> { + // 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 \ + <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\ + clarity.html>" + .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<Segment>, + parent_scope: &ParentScope<'b>, + ) -> Option<(Vec<Segment>, Option<String>)> { + // 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<Segment>, + parent_scope: &ParentScope<'b>, + ) -> Option<(Vec<Segment>, Option<String>)> { + 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::<Vec<_>>(); + 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<Suggestion>, Option<String>)> { + 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<Span> { + 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::<Vec<_>>(); + let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>(); + 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<LocalDefId, Span>, + err: &mut Diagnostic, + // This is `None` if all placement locations are inside expansions + use_placement_span: Option<Span>, + candidates: &[ImportSuggestion], + instead: Instead, + found_use: FoundUse, + is_pattern: IsPattern, + path: Vec<Segment>, +) { + if candidates.is_empty() { + return; + } + + let mut accessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> = + Vec::new(); + let mut inaccessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> = + 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::<Vec<_>>(); + 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[..] { + err.span_suggestion_verbose( + first.ident.span.until(last.ident.span), + &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<Span>, + first_use_span: Option<Span>, +} + +impl UsePlacementFinder { + fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, 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<ast::Item>]) -> Option<Span> { + 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}") +} |