Importing rustc-1.48.0
Bug: 173721343
Change-Id: Ie8184d9a685086ca8a77266d6c608843f40dc9e1
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
new file mode 100644
index 0000000..612bc3e
--- /dev/null
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -0,0 +1,1686 @@
+use std::cmp::Reverse;
+use std::ptr;
+
+use rustc_ast::util::lev_distance::find_best_match_for_name;
+use rustc_ast::{self as ast, Path};
+use rustc_ast_pretty::pprust;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
+use rustc_feature::BUILTIN_ATTRIBUTES;
+use rustc_hir::def::Namespace::{self, *};
+use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
+use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_middle::bug;
+use rustc_middle::ty::{self, DefIdTree};
+use rustc_session::Session;
+use rustc_span::hygiene::MacroKind;
+use rustc_span::source_map::SourceMap;
+use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::{BytePos, MultiSpan, Span};
+use tracing::debug;
+
+use crate::imports::{Import, ImportKind, ImportResolver};
+use crate::path_names_to_string;
+use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
+use crate::{
+ BindingError, CrateLint, HasGenericParams, MacroRulesScope, Module, ModuleOrUniformRoot,
+};
+use crate::{NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
+use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment};
+
+type Res = def::Res<ast::NodeId>;
+
+/// A vector of spans and replacements, a message and applicability.
+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.
+crate type LabelSuggestion = (Ident, bool);
+
+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<DefId>,
+ pub descr: &'static str,
+ pub path: Path,
+ pub accessible: bool,
+}
+
+/// 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> {
+ 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::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, "use of generic parameter from outer function".to_string());
+
+ let sm = 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.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"
+ );
+ }
+ }
+
+ 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"
+ .to_string(),
+ );
+ } 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_) => {
+ 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::<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 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 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.to_string(),
+ 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",
+ "".to_string(),
+ 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 {
+ 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::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::ParamInAnonConstInTyDefault(name) => {
+ let mut err = self.session.struct_span_err(
+ span,
+ "constant values inside of type parameter defaults must not depend on generic parameters",
+ );
+ err.span_label(
+ span,
+ format!("the anonymous constant must not depend on the parameter `{}`", name),
+ );
+ err
+ }
+ ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
+ let mut err = self.session.struct_span_err(
+ span,
+ "generic parameters must not be used inside of non trivial constant values",
+ );
+ err.span_label(
+ span,
+ &format!(
+ "non-trivial anonymous constants must not depend on the parameter `{}`",
+ name
+ ),
+ );
+
+ if is_type {
+ err.note("type parameters are currently not permitted in anonymous constants");
+ } else {
+ err.help(
+ &format!("it is currently only allowed to use either `{0}` or `{{ {0} }}` as generic constants",
+ name
+ )
+ );
+ }
+
+ 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
+ }
+ 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.to_string(),
+ 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
+ }
+ }
+ }
+
+ crate fn report_vis_error(&self, vis_resolution_error: VisResolutionError<'_>) {
+ match vis_resolution_error {
+ VisResolutionError::Relative2018(span, path) => {
+ let mut err = self.session.struct_span_err(
+ span,
+ "relative paths are not supported in visibilities on 2018 edition",
+ );
+ err.span_suggestion(
+ path.span,
+ "try",
+ format!("crate::{}", pprust::path_to_string(&path)),
+ Applicability::MaybeIncorrect,
+ );
+ err
+ }
+ VisResolutionError::AncestorOnly(span) => struct_span_err!(
+ self.session,
+ span,
+ E0742,
+ "visibilities can only be restricted to ancestor modules"
+ ),
+ VisResolutionError::FailedToResolve(span, label, suggestion) => {
+ self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
+ }
+ VisResolutionError::ExpectedFound(span, path_str, res) => {
+ let mut err = struct_span_err!(
+ self.session,
+ span,
+ E0577,
+ "expected module, found {} `{}`",
+ res.descr(),
+ path_str
+ );
+ err.span_label(span, "not a module");
+ err
+ }
+ VisResolutionError::Indeterminate(span) => struct_span_err!(
+ self.session,
+ span,
+ E0578,
+ "cannot determine resolution for the visibility"
+ ),
+ VisResolutionError::ModuleOnly(span) => {
+ self.session.struct_span_err(span, "visibility must resolve to a module")
+ }
+ }
+ .emit()
+ }
+
+ /// Lookup typo candidate in scope for a macro or import.
+ fn early_lookup_typo_candidate(
+ &mut self,
+ scope_set: ScopeSet,
+ parent_scope: &ParentScope<'a>,
+ ident: Ident,
+ filter_fn: &impl Fn(Res) -> bool,
+ ) -> Option<TypoSuggestion> {
+ let mut suggestions = Vec::new();
+ self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
+ match scope {
+ Scope::DeriveHelpers(expn_id) => {
+ let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
+ if filter_fn(res) {
+ suggestions.extend(
+ this.helper_attrs
+ .get(&expn_id)
+ .into_iter()
+ .flatten()
+ .map(|ident| TypoSuggestion::from_res(ident.name, res)),
+ );
+ }
+ }
+ Scope::DeriveHelpersCompat => {
+ let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
+ if filter_fn(res) {
+ for derive in parent_scope.derives {
+ let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
+ if let Ok((Some(ext), _)) = this.resolve_macro_path(
+ derive,
+ Some(MacroKind::Derive),
+ parent_scope,
+ false,
+ false,
+ ) {
+ suggestions.extend(
+ ext.helper_attrs
+ .iter()
+ .map(|name| TypoSuggestion::from_res(*name, res)),
+ );
+ }
+ }
+ }
+ }
+ Scope::MacroRules(macro_rules_scope) => {
+ if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope {
+ let res = macro_rules_binding.binding.res();
+ if filter_fn(res) {
+ suggestions
+ .push(TypoSuggestion::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::from_res(ident.name, res)),
+ );
+ }
+ }
+ Scope::MacroUsePrelude => {
+ suggestions.extend(this.macro_use_prelude.iter().filter_map(
+ |(name, binding)| {
+ let res = binding.res();
+ filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
+ },
+ ));
+ }
+ Scope::BuiltinAttrs => {
+ let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
+ if filter_fn(res) {
+ suggestions.extend(
+ BUILTIN_ATTRIBUTES
+ .iter()
+ .map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
+ );
+ }
+ }
+ Scope::ExternPrelude => {
+ suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
+ let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
+ filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
+ }));
+ }
+ Scope::ToolPrelude => {
+ let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
+ suggestions.extend(
+ this.registered_tools
+ .iter()
+ .map(|ident| TypoSuggestion::from_res(ident.name, res)),
+ );
+ }
+ Scope::StdLibPrelude => {
+ if let Some(prelude) = this.prelude {
+ let mut tmp_suggestions = Vec::new();
+ this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
+ suggestions.extend(
+ tmp_suggestions
+ .into_iter()
+ .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
+ );
+ }
+ }
+ Scope::BuiltinTypes => {
+ let primitive_types = &this.primitive_type_table.primitive_types;
+ suggestions.extend(primitive_types.iter().flat_map(|(name, prim_ty)| {
+ let res = Res::PrimTy(*prim_ty);
+ filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
+ }))
+ }
+ }
+
+ None::<()>
+ });
+
+ // Make sure error reporting is deterministic.
+ suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
+
+ match find_best_match_for_name(
+ suggestions.iter().map(|suggestion| &suggestion.candidate),
+ ident.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 not_local_module = crate_name.name != kw::Crate;
+ let mut worklist =
+ vec![(start_module, Vec::<ast::PathSegment>::new(), true, not_local_module)];
+ let mut worklist_via_import = vec![];
+
+ while let Some((in_module, path_segments, accessible, in_module_is_extern)) =
+ match worklist.pop() {
+ None => worklist_via_import.pop(),
+ Some(x) => Some(x),
+ }
+ {
+ // 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;
+ }
+
+ // collect results based on the filter function
+ // avoid suggesting anything from the same module in which we are resolving
+ if ident.name == lookup_ident.name
+ && ns == namespace
+ && !ptr::eq(in_module, parent_scope.module)
+ {
+ 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.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) {
+ candidates.push(ImportSuggestion {
+ did,
+ descr: res.descr(),
+ path,
+ accessible: child_accessible,
+ });
+ }
+ }
+ }
+
+ // 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 {
+ let is_extern = in_module_is_extern || name_binding.is_extern_crate();
+ // add the module to the lookup
+ if seen_modules.insert(module.def_id().unwrap()) {
+ if via_import { &mut worklist_via_import } else { &mut worklist }
+ .push((module, path_segments, child_accessible, is_extern));
+ }
+ }
+ }
+ })
+ }
+
+ // 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).
+ 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.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
+ suggestions.extend(self.lookup_import_candidates_from_module(
+ lookup_ident,
+ namespace,
+ parent_scope,
+ 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.name == sym::Send || ident.name == sym::Sync) {
+ let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
+ err.span_note(ident.span, &msg);
+ }
+ if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
+ err.help("have you added the `#[macro_use]` on the module/import?");
+ }
+ }
+
+ crate fn add_typo_suggestion(
+ &self,
+ err: &mut DiagnosticBuilder<'_>,
+ 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.session
+ .source_map()
+ .guess_head_span(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 followoing:
+ // 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;
+ }
+ err.span_label(
+ self.session.source_map().guess_head_span(def_span),
+ &format!(
+ "similarly named {} `{}` defined here",
+ suggestion.res.descr(),
+ suggestion.candidate.as_str(),
+ ),
+ );
+ }
+ 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,
+ );
+ true
+ }
+
+ fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
+ let res = b.res();
+ if b.span.is_dummy() {
+ let add_built_in = match b.res() {
+ // These already contain the "built-in" prefix or look bad with it.
+ Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
+ _ => true,
+ };
+ let (built_in, from) = if from_prelude {
+ ("", " from prelude")
+ } else if b.is_extern_crate()
+ && !b.is_import()
+ && self.session.opts.externs.get(&ident.as_str()).is_some()
+ {
+ ("", " passed with `--extern`")
+ } else if add_built_in {
+ (" built-in", "")
+ } else {
+ ("", "")
+ };
+
+ let article = if built_in.is_empty() { res.article() } else { "a" };
+ format!(
+ "{a}{built_in} {thing}{from}",
+ a = article,
+ thing = res.descr(),
+ built_in = built_in,
+ from = from
+ )
+ } else {
+ let introduced = if b.is_import() { "imported" } else { "defined" };
+ format!("the {thing} {introduced} here", thing = res.descr(), introduced = introduced)
+ }
+ }
+
+ crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
+ let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
+ let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
+ // We have to print the span-less alternative first, otherwise formatting looks bad.
+ (b2, b1, misc2, misc1, true)
+ } else {
+ (b1, b2, misc1, misc2, false)
+ };
+
+ let mut err = struct_span_err!(
+ self.session,
+ ident.span,
+ E0659,
+ "`{ident}` is ambiguous ({why})",
+ ident = ident,
+ why = kind.descr()
+ );
+ err.span_label(ident.span, "ambiguous name");
+
+ let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
+ let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
+ let note_msg = format!(
+ "`{ident}` could{also} refer to {what}",
+ ident = ident,
+ also = also,
+ what = what
+ );
+
+ let thing = b.res().descr();
+ let mut help_msgs = Vec::new();
+ if b.is_glob_import()
+ && (kind == AmbiguityKind::GlobVsGlob
+ || kind == AmbiguityKind::GlobVsExpanded
+ || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
+ {
+ help_msgs.push(format!(
+ "consider adding an explicit import of \
+ `{ident}` to disambiguate",
+ ident = ident
+ ))
+ }
+ if b.is_extern_crate() && ident.span.rust_2018() {
+ help_msgs.push(format!(
+ "use `::{ident}` to refer to this {thing} unambiguously",
+ ident = ident,
+ thing = thing,
+ ))
+ }
+ if misc == AmbiguityErrorMisc::SuggestCrate {
+ help_msgs.push(format!(
+ "use `crate::{ident}` to refer to this {thing} unambiguously",
+ ident = ident,
+ thing = thing,
+ ))
+ } else if misc == AmbiguityErrorMisc::SuggestSelf {
+ help_msgs.push(format!(
+ "use `self::{ident}` to refer to this {thing} unambiguously",
+ ident = ident,
+ thing = thing,
+ ))
+ }
+
+ err.span_note(b.span, ¬e_msg);
+ for (i, help_msg) in help_msgs.iter().enumerate() {
+ let or = if i == 0 { "" } else { "or " };
+ err.help(&format!("{}{}", or, help_msg));
+ }
+ };
+
+ could_refer_to(b1, misc1, "");
+ could_refer_to(b2, misc2, " also");
+ err.emit();
+ }
+
+ /// 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).expect("no parent for a constructor");
+ let fields = self.field_names.get(&def_id)?;
+ let first_field = fields.first()?; // Handle `struct Foo()`
+ return Some(fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)));
+ }
+ None
+ }
+
+ crate 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 descr = get_descr(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 = descr,
+ name = name,
+ 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 == ty::Visibility::Public {
+ note_span.push_span_label(def_span, "consider importing it directly".into());
+ }
+ err.span_note(note_span, &msg);
+ }
+
+ err.emit();
+ }
+}
+
+impl<'a, 'b> ImportResolver<'a, 'b> {
+ /// Adds suggestions for a path that cannot be resolved.
+ pub(crate) fn make_path_suggestion(
+ &mut self,
+ span: Span,
+ mut path: Vec<Segment>,
+ parent_scope: &ParentScope<'b>,
+ ) -> Option<(Vec<Segment>, Vec<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::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.
+ ///
+ /// ```text
+ /// |
+ /// LL | use foo::Bar;
+ /// | ^^^ did you mean `self::foo`?
+ /// ```
+ fn make_missing_self_suggestion(
+ &mut self,
+ span: Span,
+ mut path: Vec<Segment>,
+ parent_scope: &ParentScope<'b>,
+ ) -> Option<(Vec<Segment>, Vec<String>)> {
+ // 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.
+ ///
+ /// ```text
+ /// |
+ /// LL | use foo::Bar;
+ /// | ^^^ did you mean `crate::foo`?
+ /// ```
+ fn make_missing_crate_suggestion(
+ &mut self,
+ span: Span,
+ mut path: Vec<Segment>,
+ parent_scope: &ParentScope<'b>,
+ ) -> Option<(Vec<Segment>, Vec<String>)> {
+ // 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 \
+ <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,
+ span: Span,
+ mut path: Vec<Segment>,
+ parent_scope: &ParentScope<'b>,
+ ) -> Option<(Vec<Segment>, Vec<String>)> {
+ // 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.
+ ///
+ /// ```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,
+ span: Span,
+ mut path: Vec<Segment>,
+ parent_scope: &ParentScope<'b>,
+ ) -> Option<(Vec<Segment>, Vec<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_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.
+ ///
+ /// ```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>, Vec<String>)> {
+ 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_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 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,
+ 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,
+ ));
+ 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<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.
+///
+/// ```
+/// 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
+ use_placement_span: Option<Span>,
+ candidates: &[ImportSuggestion],
+ instead: bool,
+ found_use: bool,
+) {
+ if candidates.is_empty() {
+ return;
+ }
+
+ // we want consistent results across executions, but candidates are produced
+ // by iterating through a hash map, so make sure they are ordered:
+ let mut path_strings: Vec<_> =
+ candidates.iter().map(|c| path_names_to_string(&c.path)).collect();
+
+ path_strings.sort();
+ path_strings.dedup();
+
+ let (determiner, kind) = if candidates.len() == 1 {
+ ("this", candidates[0].descr)
+ } else {
+ ("one of these", "items")
+ };
+
+ let instead = if instead { " instead" } else { "" };
+ let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
+
+ if let Some(span) = use_placement_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 {
+ msg.push(':');
+
+ for candidate in path_strings {
+ msg.push('\n');
+ msg.push_str(&candidate);
+ }
+
+ err.note(&msg);
+ }
+}
