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