1 //! A bunch of methods and structures more or less related to resolving imports.
3 use ImportDirectiveSubclass::*;
5 use crate::diagnostics::Suggestion;
6 use crate::Determinacy::{self, *};
7 use crate::Namespace::{self, MacroNS, TypeNS};
8 use crate::{module_to_string, names_to_string};
9 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
10 use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
11 use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak};
12 use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
14 use errors::{pluralize, Applicability};
16 use rustc::hir::def::{self, Export, PartialRes};
17 use rustc::hir::def_id::DefId;
18 use rustc::lint::builtin::BuiltinLintDiagnostics;
19 use rustc::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
20 use rustc::session::DiagnosticMessageId;
22 use rustc::util::nodemap::FxHashSet;
23 use rustc::{bug, span_bug};
24 use rustc_data_structures::ptr_key::PtrKey;
26 use rustc_span::hygiene::ExpnId;
27 use rustc_span::symbol::kw;
28 use rustc_span::{MultiSpan, Span};
29 use syntax::ast::{Ident, Name, NodeId};
30 use syntax::util::lev_distance::find_best_match_for_name;
31 use syntax::{struct_span_err, unwrap_or};
33 use rustc_error_codes::*;
40 type Res = def::Res<NodeId>;
42 /// Contains data for specific types of import directives.
43 #[derive(Clone, Debug)]
44 pub enum ImportDirectiveSubclass<'a> {
46 /// `source` in `use prefix::source as target`.
48 /// `target` in `use prefix::source as target`.
50 /// Bindings to which `source` refers to.
51 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
52 /// Bindings introduced by `target`.
53 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
54 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
56 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
61 max_vis: Cell<ty::Visibility>, // The visibility of the greatest re-export.
62 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
71 /// One import directive.
72 #[derive(Debug, Clone)]
73 crate struct ImportDirective<'a> {
74 /// The ID of the `extern crate`, `UseTree` etc that imported this `ImportDirective`.
76 /// In the case where the `ImportDirective` was expanded from a "nested" use tree,
77 /// this id is the ID of the leaf tree. For example:
79 /// ```ignore (pacify the mercilous tidy)
80 /// use foo::bar::{a, b}
83 /// If this is the import directive for `foo::bar::a`, we would have the ID of the `UseTree`
84 /// for `a` in this field.
87 /// The `id` of the "root" use-kind -- this is always the same as
88 /// `id` except in the case of "nested" use trees, in which case
89 /// it will be the `id` of the root use tree. e.g., in the example
90 /// from `id`, this would be the ID of the `use foo::bar`
94 /// Span of the entire use statement.
97 /// Span of the entire use statement with attributes.
98 pub use_span_with_attributes: Span,
100 /// Did the use statement have any attributes?
101 pub has_attributes: bool,
103 /// Span of this use tree.
106 /// Span of the *root* use tree (see `root_id`).
109 pub parent_scope: ParentScope<'a>,
110 pub module_path: Vec<Segment>,
111 /// The resolution of `module_path`.
112 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
113 pub subclass: ImportDirectiveSubclass<'a>,
114 pub vis: Cell<ty::Visibility>,
115 pub used: Cell<bool>,
118 impl<'a> ImportDirective<'a> {
119 pub fn is_glob(&self) -> bool {
120 match self.subclass {
121 ImportDirectiveSubclass::GlobImport { .. } => true,
126 pub fn is_nested(&self) -> bool {
127 match self.subclass {
128 ImportDirectiveSubclass::SingleImport { nested, .. } => nested,
133 crate fn crate_lint(&self) -> CrateLint {
134 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
138 #[derive(Clone, Default, Debug)]
139 /// Records information about the resolution of a name in a namespace of a module.
140 pub struct NameResolution<'a> {
141 /// Single imports that may define the name in the namespace.
142 /// Import directives are arena-allocated, so it's ok to use pointers as keys.
143 single_imports: FxHashSet<PtrKey<'a, ImportDirective<'a>>>,
144 /// The least shadowable known binding for this name, or None if there are no known bindings.
145 pub binding: Option<&'a NameBinding<'a>>,
146 shadowed_glob: Option<&'a NameBinding<'a>>,
149 impl<'a> NameResolution<'a> {
150 // Returns the binding for the name if it is known or None if it not known.
151 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
152 self.binding.and_then(|binding| {
153 if !binding.is_glob_import() || self.single_imports.is_empty() {
161 crate fn add_single_import(&mut self, directive: &'a ImportDirective<'a>) {
162 self.single_imports.insert(PtrKey(directive));
166 impl<'a> Resolver<'a> {
167 crate fn resolve_ident_in_module_unadjusted(
169 module: ModuleOrUniformRoot<'a>,
172 parent_scope: &ParentScope<'a>,
175 ) -> Result<&'a NameBinding<'a>, Determinacy> {
176 self.resolve_ident_in_module_unadjusted_ext(
185 .map_err(|(determinacy, _)| determinacy)
188 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
189 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
190 crate fn resolve_ident_in_module_unadjusted_ext(
192 module: ModuleOrUniformRoot<'a>,
195 parent_scope: &ParentScope<'a>,
196 restricted_shadowing: bool,
199 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
200 let module = match module {
201 ModuleOrUniformRoot::Module(module) => module,
202 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
203 assert!(!restricted_shadowing);
204 let binding = self.early_resolve_ident_in_lexical_scope(
206 ScopeSet::AbsolutePath(ns),
212 return binding.map_err(|determinacy| (determinacy, Weak::No));
214 ModuleOrUniformRoot::ExternPrelude => {
215 assert!(!restricted_shadowing);
216 return if ns != TypeNS {
217 Err((Determined, Weak::No))
218 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
220 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
221 // Macro-expanded `extern crate` items can add names to extern prelude.
222 Err((Undetermined, Weak::No))
224 Err((Determined, Weak::No))
227 ModuleOrUniformRoot::CurrentScope => {
228 assert!(!restricted_shadowing);
230 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
231 let module = self.resolve_crate_root(ident);
232 let binding = (module, ty::Visibility::Public, module.span, ExpnId::root())
233 .to_name_binding(self.arenas);
235 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
236 // FIXME: Implement these with renaming requirements so that e.g.
237 // `use super;` doesn't work, but `use super as name;` does.
238 // Fall through here to get an error from `early_resolve_...`.
242 let scopes = ScopeSet::All(ns, true);
243 let binding = self.early_resolve_ident_in_lexical_scope(
251 return binding.map_err(|determinacy| (determinacy, Weak::No));
255 let key = self.new_key(ident, ns);
257 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
259 if let Some(binding) = resolution.binding {
260 if !restricted_shadowing && binding.expansion != ExpnId::root() {
261 if let NameBindingKind::Res(_, true) = binding.kind {
262 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
267 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
268 if let Some(blacklisted_binding) = this.blacklisted_binding {
269 if ptr::eq(binding, blacklisted_binding) {
270 return Err((Determined, Weak::No));
273 // `extern crate` are always usable for backwards compatibility, see issue #37020,
274 // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
275 let usable = this.is_accessible_from(binding.vis, parent_scope.module)
276 || binding.is_extern_crate();
277 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
283 .and_then(|binding| {
284 // If the primary binding is blacklisted, search further and return the shadowed
285 // glob binding if it exists. What we really want here is having two separate
286 // scopes in a module - one for non-globs and one for globs, but until that's done
287 // use this hack to avoid inconsistent resolution ICEs during import validation.
288 if let Some(blacklisted_binding) = self.blacklisted_binding {
289 if ptr::eq(binding, blacklisted_binding) {
290 return resolution.shadowed_glob;
295 .ok_or((Determined, Weak::No))
296 .and_then(|binding| {
297 if self.last_import_segment && check_usable(self, binding).is_err() {
298 Err((Determined, Weak::No))
300 self.record_use(ident, ns, binding, restricted_shadowing);
302 if let Some(shadowed_glob) = resolution.shadowed_glob {
303 // Forbid expanded shadowing to avoid time travel.
304 if restricted_shadowing
305 && binding.expansion != ExpnId::root()
306 && binding.res() != shadowed_glob.res()
308 self.ambiguity_errors.push(AmbiguityError {
309 kind: AmbiguityKind::GlobVsExpanded,
313 misc1: AmbiguityErrorMisc::None,
314 misc2: AmbiguityErrorMisc::None,
319 if !self.is_accessible_from(binding.vis, parent_scope.module) &&
320 // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
321 !(self.last_import_segment && binding.is_extern_crate())
323 self.privacy_errors.push(PrivacyError(path_span, ident, binding));
331 // Items and single imports are not shadowable, if we have one, then it's determined.
332 if let Some(binding) = resolution.binding {
333 if !binding.is_glob_import() {
334 return check_usable(self, binding);
338 // --- From now on we either have a glob resolution or no resolution. ---
340 // Check if one of single imports can still define the name,
341 // if it can then our result is not determined and can be invalidated.
342 for single_import in &resolution.single_imports {
343 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
346 let module = unwrap_or!(
347 single_import.imported_module.get(),
348 return Err((Undetermined, Weak::No))
350 let ident = match single_import.subclass {
351 SingleImport { source, .. } => source,
354 match self.resolve_ident_in_module(
358 &single_import.parent_scope,
362 Err(Determined) => continue,
364 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
368 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
372 // So we have a resolution that's from a glob import. This resolution is determined
373 // if it cannot be shadowed by some new item/import expanded from a macro.
374 // This happens either if there are no unexpanded macros, or expanded names cannot
375 // shadow globs (that happens in macro namespace or with restricted shadowing).
377 // Additionally, any macro in any module can plant names in the root module if it creates
378 // `macro_export` macros, so the root module effectively has unresolved invocations if any
379 // module has unresolved invocations.
380 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
381 // progress, we have to ignore those potential unresolved invocations from other modules
382 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
383 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
384 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
385 if let Some(binding) = resolution.binding {
386 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
387 return check_usable(self, binding);
389 return Err((Undetermined, Weak::No));
393 // --- From now on we have no resolution. ---
395 // Now we are in situation when new item/import can appear only from a glob or a macro
396 // expansion. With restricted shadowing names from globs and macro expansions cannot
397 // shadow names from outer scopes, so we can freely fallback from module search to search
398 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
399 // scopes we return `Undetermined` with `Weak::Yes`.
401 // Check if one of unexpanded macros can still define the name,
402 // if it can then our "no resolution" result is not determined and can be invalidated.
403 if unexpanded_macros {
404 return Err((Undetermined, Weak::Yes));
407 // Check if one of glob imports can still define the name,
408 // if it can then our "no resolution" result is not determined and can be invalidated.
409 for glob_import in module.globs.borrow().iter() {
410 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
413 let module = match glob_import.imported_module.get() {
414 Some(ModuleOrUniformRoot::Module(module)) => module,
416 None => return Err((Undetermined, Weak::Yes)),
418 let tmp_parent_scope;
419 let (mut adjusted_parent_scope, mut ident) = (parent_scope, ident.modern());
420 match ident.span.glob_adjust(module.expansion, glob_import.span) {
423 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
424 adjusted_parent_scope = &tmp_parent_scope;
429 let result = self.resolve_ident_in_module_unadjusted(
430 ModuleOrUniformRoot::Module(module),
433 adjusted_parent_scope,
439 Err(Determined) => continue,
441 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
445 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
449 // No resolution and no one else can define the name - determinate error.
450 Err((Determined, Weak::No))
453 // Given a binding and an import directive that resolves to it,
454 // return the corresponding binding defined by the import directive.
457 binding: &'a NameBinding<'a>,
458 directive: &'a ImportDirective<'a>,
459 ) -> &'a NameBinding<'a> {
460 let vis = if binding.pseudo_vis().is_at_least(directive.vis.get(), self) ||
461 // cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
462 !directive.is_glob() && binding.is_extern_crate()
469 if let GlobImport { ref max_vis, .. } = directive.subclass {
470 if vis == directive.vis.get() || vis.is_at_least(max_vis.get(), self) {
475 self.arenas.alloc_name_binding(NameBinding {
476 kind: NameBindingKind::Import { binding, directive, used: Cell::new(false) },
478 span: directive.span,
480 expansion: directive.parent_scope.expansion,
484 // Define the name or return the existing binding if there is a collision.
489 binding: &'a NameBinding<'a>,
490 ) -> Result<(), &'a NameBinding<'a>> {
491 let res = binding.res();
492 self.check_reserved_macro_name(key.ident, res);
493 self.set_binding_parent_module(binding, module);
494 self.update_resolution(module, key, |this, resolution| {
495 if let Some(old_binding) = resolution.binding {
497 // Do not override real bindings with `Res::Err`s from error recovery.
500 match (old_binding.is_glob_import(), binding.is_glob_import()) {
502 if res != old_binding.res() {
503 resolution.binding = Some(this.ambiguity(
504 AmbiguityKind::GlobVsGlob,
508 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
509 // We are glob-importing the same item but with greater visibility.
510 resolution.binding = Some(binding);
513 (old_glob @ true, false) | (old_glob @ false, true) => {
514 let (glob_binding, nonglob_binding) =
515 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
516 if glob_binding.res() != nonglob_binding.res()
518 && nonglob_binding.expansion != ExpnId::root()
520 resolution.binding = Some(this.ambiguity(
521 AmbiguityKind::GlobVsExpanded,
526 resolution.binding = Some(nonglob_binding);
528 resolution.shadowed_glob = Some(glob_binding);
531 return Err(old_binding);
535 resolution.binding = Some(binding);
545 primary_binding: &'a NameBinding<'a>,
546 secondary_binding: &'a NameBinding<'a>,
547 ) -> &'a NameBinding<'a> {
548 self.arenas.alloc_name_binding(NameBinding {
549 ambiguity: Some((secondary_binding, kind)),
550 ..primary_binding.clone()
554 // Use `f` to mutate the resolution of the name in the module.
555 // If the resolution becomes a success, define it in the module's glob importers.
556 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
558 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
560 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
561 // during which the resolution might end up getting re-defined via a glob cycle.
563 let resolution = &mut *self.resolution(module, key).borrow_mut();
564 let old_binding = resolution.binding();
566 let t = f(self, resolution);
568 match resolution.binding() {
569 _ if old_binding.is_some() => return t,
571 Some(binding) => match old_binding {
572 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
578 // Define `binding` in `module`s glob importers.
579 for directive in module.glob_importers.borrow_mut().iter() {
580 let mut ident = key.ident;
581 let scope = match ident.span.reverse_glob_adjust(module.expansion, directive.span) {
582 Some(Some(def)) => self.macro_def_scope(def),
583 Some(None) => directive.parent_scope.module,
586 if self.is_accessible_from(binding.vis, scope) {
587 let imported_binding = self.import(binding, directive);
588 let key = BindingKey { ident, ..key };
589 let _ = self.try_define(directive.parent_scope.module, key, imported_binding);
596 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
598 fn import_dummy_binding(&mut self, directive: &'a ImportDirective<'a>) {
599 if let SingleImport { target, .. } = directive.subclass {
600 let dummy_binding = self.dummy_binding;
601 let dummy_binding = self.import(dummy_binding, directive);
602 self.per_ns(|this, ns| {
603 let key = this.new_key(target, ns);
604 let _ = this.try_define(directive.parent_scope.module, key, dummy_binding);
605 // Consider erroneous imports used to avoid duplicate diagnostics.
606 this.record_use(target, ns, dummy_binding, false);
612 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
613 /// import errors within the same use tree into a single diagnostic.
614 #[derive(Debug, Clone)]
615 struct UnresolvedImportError {
617 label: Option<String>,
619 suggestion: Option<Suggestion>,
622 pub struct ImportResolver<'a, 'b> {
623 pub r: &'a mut Resolver<'b>,
626 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
627 fn parent(self, id: DefId) -> Option<DefId> {
632 impl<'a, 'b> ImportResolver<'a, 'b> {
635 // This is a fixed-point algorithm. We resolve imports until our efforts
636 // are stymied by an unresolved import; then we bail out of the current
637 // module and continue. We terminate successfully once no more imports
638 // remain or unsuccessfully when no forward progress in resolving imports
641 /// Resolves all imports for the crate. This method performs the fixed-
643 pub fn resolve_imports(&mut self) {
644 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
645 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
646 prev_num_indeterminates = self.r.indeterminate_imports.len();
647 for import in mem::take(&mut self.r.indeterminate_imports) {
648 match self.resolve_import(&import) {
649 true => self.r.determined_imports.push(import),
650 false => self.r.indeterminate_imports.push(import),
656 pub fn finalize_imports(&mut self) {
657 for module in self.r.arenas.local_modules().iter() {
658 self.finalize_resolutions_in(module);
661 let mut seen_spans = FxHashSet::default();
662 let mut errors = vec![];
663 let mut prev_root_id: NodeId = NodeId::from_u32(0);
664 let determined_imports = mem::take(&mut self.r.determined_imports);
665 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
667 for (is_indeterminate, import) in determined_imports
670 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
672 if let Some(err) = self.finalize_import(import) {
673 if let SingleImport { source, ref source_bindings, .. } = import.subclass {
674 if source.name == kw::SelfLower {
675 // Silence `unresolved import` error if E0429 is already emitted
676 if let Err(Determined) = source_bindings.value_ns.get() {
682 // If the error is a single failed import then create a "fake" import
683 // resolution for it so that later resolve stages won't complain.
684 self.r.import_dummy_binding(import);
685 if prev_root_id.as_u32() != 0
686 && prev_root_id.as_u32() != import.root_id.as_u32()
687 && !errors.is_empty()
689 // In the case of a new import line, throw a diagnostic message
690 // for the previous line.
691 self.throw_unresolved_import_error(errors, None);
694 if seen_spans.insert(err.span) {
695 let path = import_path_to_string(
696 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
700 errors.push((path, err));
701 prev_root_id = import.root_id;
703 } else if is_indeterminate {
704 // Consider erroneous imports used to avoid duplicate diagnostics.
705 self.r.used_imports.insert((import.id, TypeNS));
706 let path = import_path_to_string(
707 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
711 let err = UnresolvedImportError {
717 errors.push((path, err));
721 if !errors.is_empty() {
722 self.throw_unresolved_import_error(errors.clone(), None);
726 fn throw_unresolved_import_error(
728 errors: Vec<(String, UnresolvedImportError)>,
729 span: Option<MultiSpan>,
731 /// Upper limit on the number of `span_label` messages.
732 const MAX_LABEL_COUNT: usize = 10;
734 let (span, msg) = if errors.is_empty() {
735 (span.unwrap(), "unresolved import".to_string())
737 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
739 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
741 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
746 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
748 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
749 for message in note {
754 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
755 if let Some(label) = err.label {
756 diag.span_label(err.span, label);
759 if let Some((suggestions, msg, applicability)) = err.suggestion {
760 diag.multipart_suggestion(&msg, suggestions, applicability);
767 /// Attempts to resolve the given import, returning true if its resolution is determined.
768 /// If successful, the resolved bindings are written into the module.
769 fn resolve_import(&mut self, directive: &'b ImportDirective<'b>) -> bool {
771 "(resolving import for module) resolving import `{}::...` in `{}`",
772 Segment::names_to_string(&directive.module_path),
773 module_to_string(directive.parent_scope.module).unwrap_or_else(|| "???".to_string()),
776 let module = if let Some(module) = directive.imported_module.get() {
779 // For better failure detection, pretend that the import will
780 // not define any names while resolving its module path.
781 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
782 let path_res = self.r.resolve_path(
783 &directive.module_path,
785 &directive.parent_scope,
788 directive.crate_lint(),
790 directive.vis.set(orig_vis);
793 PathResult::Module(module) => module,
794 PathResult::Indeterminate => return false,
795 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
799 directive.imported_module.set(Some(module));
800 let (source, target, source_bindings, target_bindings, type_ns_only) =
801 match directive.subclass {
809 } => (source, target, source_bindings, target_bindings, type_ns_only),
810 GlobImport { .. } => {
811 self.resolve_glob_import(directive);
817 let mut indeterminate = false;
818 self.r.per_ns(|this, ns| {
819 if !type_ns_only || ns == TypeNS {
820 if let Err(Undetermined) = source_bindings[ns].get() {
821 // For better failure detection, pretend that the import will
822 // not define any names while resolving its module path.
823 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
824 let binding = this.resolve_ident_in_module(
828 &directive.parent_scope,
832 directive.vis.set(orig_vis);
834 source_bindings[ns].set(binding);
839 let parent = directive.parent_scope.module;
840 match source_bindings[ns].get() {
841 Err(Undetermined) => indeterminate = true,
842 // Don't update the resolution, because it was never added.
843 Err(Determined) if target.name == kw::Underscore => {}
845 let key = this.new_key(target, ns);
846 this.update_resolution(parent, key, |_, resolution| {
847 resolution.single_imports.remove(&PtrKey(directive));
850 Ok(binding) if !binding.is_importable() => {
851 let msg = format!("`{}` is not directly importable", target);
852 struct_span_err!(this.session, directive.span, E0253, "{}", &msg)
853 .span_label(directive.span, "cannot be imported directly")
855 // Do not import this illegal binding. Import a dummy binding and pretend
856 // everything is fine
857 this.import_dummy_binding(directive);
860 let imported_binding = this.import(binding, directive);
861 target_bindings[ns].set(Some(imported_binding));
862 this.define(parent, target, ns, imported_binding);
871 /// Performs final import resolution, consistency checks and error reporting.
873 /// Optionally returns an unresolved import error. This error is buffered and used to
874 /// consolidate multiple unresolved import errors into a single diagnostic.
877 directive: &'b ImportDirective<'b>,
878 ) -> Option<UnresolvedImportError> {
879 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
880 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
881 let path_res = self.r.resolve_path(
882 &directive.module_path,
884 &directive.parent_scope,
887 directive.crate_lint(),
889 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
890 directive.vis.set(orig_vis);
891 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
892 // Consider erroneous imports used to avoid duplicate diagnostics.
893 self.r.used_imports.insert((directive.id, TypeNS));
895 let module = match path_res {
896 PathResult::Module(module) => {
897 // Consistency checks, analogous to `finalize_macro_resolutions`.
898 if let Some(initial_module) = directive.imported_module.get() {
899 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
900 span_bug!(directive.span, "inconsistent resolution for an import");
903 if self.r.privacy_errors.is_empty() {
904 let msg = "cannot determine resolution for the import";
905 let msg_note = "import resolution is stuck, try simplifying other imports";
906 self.r.session.struct_span_err(directive.span, msg).note(msg_note).emit();
912 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
914 assert!(directive.imported_module.get().is_none());
916 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
920 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
922 assert!(directive.imported_module.get().is_none());
923 let err = match self.make_path_suggestion(
925 directive.module_path.clone(),
926 &directive.parent_scope,
928 Some((suggestion, note)) => UnresolvedImportError {
933 vec![(span, Segment::names_to_string(&suggestion))],
934 String::from("a similar path exists"),
935 Applicability::MaybeIncorrect,
938 None => UnresolvedImportError {
949 PathResult::NonModule(path_res) if path_res.base_res() == Res::Err => {
951 assert!(directive.imported_module.get().is_none());
953 // The error was already reported earlier.
956 PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(),
959 let (ident, target, source_bindings, target_bindings, type_ns_only) = match directive
969 } => (source, target, source_bindings, target_bindings, type_ns_only),
970 GlobImport { is_prelude, ref max_vis } => {
971 if directive.module_path.len() <= 1 {
972 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
973 // 2 segments, so the `resolve_path` above won't trigger it.
974 let mut full_path = directive.module_path.clone();
975 full_path.push(Segment::from_ident(Ident::invalid()));
976 self.r.lint_if_path_starts_with_module(
977 directive.crate_lint(),
984 if let ModuleOrUniformRoot::Module(module) = module {
985 if module.def_id() == directive.parent_scope.module.def_id() {
986 // Importing a module into itself is not allowed.
987 return Some(UnresolvedImportError {
988 span: directive.span,
989 label: Some(String::from("cannot glob-import a module into itself")),
996 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
997 !max_vis.get().is_at_least(directive.vis.get(), &*self)
999 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1000 self.r.lint_buffer.buffer_lint(
1009 _ => unreachable!(),
1012 let mut all_ns_err = true;
1013 self.r.per_ns(|this, ns| {
1014 if !type_ns_only || ns == TypeNS {
1015 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
1016 let orig_blacklisted_binding =
1017 mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get());
1018 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1019 let binding = this.resolve_ident_in_module(
1023 &directive.parent_scope,
1027 this.last_import_segment = orig_last_import_segment;
1028 this.blacklisted_binding = orig_blacklisted_binding;
1029 directive.vis.set(orig_vis);
1033 // Consistency checks, analogous to `finalize_macro_resolutions`.
1034 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1036 if let Some(target_binding) = target_bindings[ns].get() {
1037 // Note that as_str() de-gensyms the Symbol
1038 if target.name.as_str() == "_"
1039 && initial_binding.is_extern_crate()
1040 && !initial_binding.is_import()
1046 directive.module_path.is_empty(),
1050 initial_binding.res()
1052 let res = binding.res();
1053 if let Ok(initial_res) = initial_res {
1054 if res != initial_res && this.ambiguity_errors.is_empty() {
1055 span_bug!(directive.span, "inconsistent resolution for an import");
1059 && this.ambiguity_errors.is_empty()
1060 && this.privacy_errors.is_empty()
1062 let msg = "cannot determine resolution for the import";
1064 "import resolution is stuck, try simplifying other imports";
1066 .struct_span_err(directive.span, msg)
1073 // FIXME: This assert may fire if public glob is later shadowed by a private
1074 // single import (see test `issue-55884-2.rs`). In theory single imports should
1075 // always block globs, even if they are not yet resolved, so that this kind of
1076 // self-inconsistent resolution never happens.
1077 // Reenable the assert when the issue is fixed.
1078 // assert!(result[ns].get().is_err());
1085 let mut all_ns_failed = true;
1086 self.r.per_ns(|this, ns| {
1087 if !type_ns_only || ns == TypeNS {
1088 let binding = this.resolve_ident_in_module(
1092 &directive.parent_scope,
1096 if binding.is_ok() {
1097 all_ns_failed = false;
1102 return if all_ns_failed {
1103 let resolutions = match module {
1104 ModuleOrUniformRoot::Module(module) => {
1105 Some(self.r.resolutions(module).borrow())
1109 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1110 let names = resolutions.filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1113 } // Never suggest the same name
1114 match *resolution.borrow() {
1115 NameResolution { binding: Some(name_binding), .. } => {
1116 match name_binding.kind {
1117 NameBindingKind::Import { binding, .. } => {
1118 match binding.kind {
1119 // Never suggest the name that has binding error
1120 // i.e., the name that cannot be previously resolved
1121 NameBindingKind::Res(Res::Err, _) => return None,
1128 NameResolution { ref single_imports, .. } if single_imports.is_empty() => {
1135 let lev_suggestion =
1136 find_best_match_for_name(names, &ident.as_str(), None).map(|suggestion| {
1138 vec![(ident.span, suggestion.to_string())],
1139 String::from("a similar name exists in the module"),
1140 Applicability::MaybeIncorrect,
1144 let (suggestion, note) =
1145 match self.check_for_module_export_macro(directive, module, ident) {
1146 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
1147 _ => (lev_suggestion, Vec::new()),
1150 let label = match module {
1151 ModuleOrUniformRoot::Module(module) => {
1152 let module_str = module_to_string(module);
1153 if let Some(module_str) = module_str {
1154 format!("no `{}` in `{}`", ident, module_str)
1156 format!("no `{}` in the root", ident)
1160 if !ident.is_path_segment_keyword() {
1161 format!("no `{}` external crate", ident)
1163 // HACK(eddyb) this shows up for `self` & `super`, which
1164 // should work instead - for now keep the same error message.
1165 format!("no `{}` in the root", ident)
1170 Some(UnresolvedImportError {
1171 span: directive.span,
1177 // `resolve_ident_in_module` reported a privacy error.
1178 self.r.import_dummy_binding(directive);
1183 let mut reexport_error = None;
1184 let mut any_successful_reexport = false;
1185 self.r.per_ns(|this, ns| {
1186 if let Ok(binding) = source_bindings[ns].get() {
1187 let vis = directive.vis.get();
1188 if !binding.pseudo_vis().is_at_least(vis, &*this) {
1189 reexport_error = Some((ns, binding));
1191 any_successful_reexport = true;
1196 // All namespaces must be re-exported with extra visibility for an error to occur.
1197 if !any_successful_reexport {
1198 let (ns, binding) = reexport_error.unwrap();
1199 if ns == TypeNS && binding.is_extern_crate() {
1201 "extern crate `{}` is private, and cannot be \
1202 re-exported (error E0365), consider declaring with \
1206 self.r.lint_buffer.buffer_lint(
1207 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1212 } else if ns == TypeNS {
1217 "`{}` is private, and cannot be re-exported",
1220 .span_label(directive.span, format!("re-export of private `{}`", ident))
1221 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1224 let msg = format!("`{}` is private, and cannot be re-exported", ident);
1226 format!("consider marking `{}` as `pub` in the imported module", ident,);
1227 struct_span_err!(self.r.session, directive.span, E0364, "{}", &msg)
1228 .span_note(directive.span, ¬e_msg)
1233 if directive.module_path.len() <= 1 {
1234 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1235 // 2 segments, so the `resolve_path` above won't trigger it.
1236 let mut full_path = directive.module_path.clone();
1237 full_path.push(Segment::from_ident(ident));
1238 self.r.per_ns(|this, ns| {
1239 if let Ok(binding) = source_bindings[ns].get() {
1240 this.lint_if_path_starts_with_module(
1241 directive.crate_lint(),
1250 // Record what this import resolves to for later uses in documentation,
1251 // this may resolve to either a value or a type, but for documentation
1252 // purposes it's good enough to just favor one over the other.
1253 self.r.per_ns(|this, ns| {
1254 if let Some(binding) = source_bindings[ns].get().ok() {
1255 this.import_res_map.entry(directive.id).or_default()[ns] = Some(binding.res());
1259 self.check_for_redundant_imports(
1267 debug!("(resolving single import) successfully resolved import");
1271 fn check_for_redundant_imports(
1274 directive: &'b ImportDirective<'b>,
1275 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1276 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1279 // Skip if the import was produced by a macro.
1280 if directive.parent_scope.expansion != ExpnId::root() {
1284 // Skip if we are inside a named module (in contrast to an anonymous
1285 // module defined by a block).
1286 if let ModuleKind::Def(..) = directive.parent_scope.module.kind {
1290 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1292 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1294 self.r.per_ns(|this, ns| {
1295 if let Some(binding) = source_bindings[ns].get().ok() {
1296 if binding.res() == Res::Err {
1300 let orig_blacklisted_binding =
1301 mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get());
1303 match this.early_resolve_ident_in_lexical_scope(
1305 ScopeSet::All(ns, false),
1306 &directive.parent_scope,
1311 Ok(other_binding) => {
1312 is_redundant[ns] = Some(
1313 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1315 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1317 Err(_) => is_redundant[ns] = Some(false),
1320 this.blacklisted_binding = orig_blacklisted_binding;
1324 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1326 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1327 redundant_spans.sort();
1328 redundant_spans.dedup();
1329 self.r.lint_buffer.buffer_lint_with_diagnostic(
1333 &format!("the item `{}` is imported redundantly", ident),
1334 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1339 fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) {
1340 let module = match directive.imported_module.get().unwrap() {
1341 ModuleOrUniformRoot::Module(module) => module,
1343 self.r.session.span_err(directive.span, "cannot glob-import all possible crates");
1348 if module.is_trait() {
1349 self.r.session.span_err(directive.span, "items in traits are not importable.");
1351 } else if module.def_id() == directive.parent_scope.module.def_id() {
1353 } else if let GlobImport { is_prelude: true, .. } = directive.subclass {
1354 self.r.prelude = Some(module);
1358 // Add to module's glob_importers
1359 module.glob_importers.borrow_mut().push(directive);
1361 // Ensure that `resolutions` isn't borrowed during `try_define`,
1362 // since it might get updated via a glob cycle.
1365 .resolutions(module)
1368 .filter_map(|(key, resolution)| {
1369 resolution.borrow().binding().map(|binding| (*key, binding))
1371 .collect::<Vec<_>>();
1372 for (mut key, binding) in bindings {
1373 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, directive.span) {
1374 Some(Some(def)) => self.r.macro_def_scope(def),
1375 Some(None) => directive.parent_scope.module,
1378 if self.r.is_accessible_from(binding.pseudo_vis(), scope) {
1379 let imported_binding = self.r.import(binding, directive);
1380 let _ = self.r.try_define(directive.parent_scope.module, key, imported_binding);
1384 // Record the destination of this import
1385 self.r.record_partial_res(directive.id, PartialRes::new(module.res().unwrap()));
1388 // Miscellaneous post-processing, including recording re-exports,
1389 // reporting conflicts, and reporting unresolved imports.
1390 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1391 // Since import resolution is finished, globs will not define any more names.
1392 *module.globs.borrow_mut() = Vec::new();
1394 let mut reexports = Vec::new();
1396 module.for_each_child(self.r, |this, ident, ns, binding| {
1397 // Filter away ambiguous imports and anything that has def-site
1399 // FIXME: Implement actual cross-crate hygiene.
1400 let is_good_import =
1401 binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
1402 if is_good_import || binding.is_macro_def() {
1403 let res = binding.res();
1404 if res != Res::Err {
1405 if let Some(def_id) = res.opt_def_id() {
1406 if !def_id.is_local() {
1407 this.cstore().export_macros_untracked(def_id.krate);
1410 reexports.push(Export { ident, res, span: binding.span, vis: binding.vis });
1414 if let NameBindingKind::Import { binding: orig_binding, directive, .. } = binding.kind {
1416 && orig_binding.is_variant()
1417 && !orig_binding.vis.is_at_least(binding.vis, &*this)
1419 let msg = match directive.subclass {
1420 ImportDirectiveSubclass::SingleImport { .. } => {
1421 format!("variant `{}` is private and cannot be re-exported", ident)
1423 ImportDirectiveSubclass::GlobImport { .. } => {
1424 let msg = "enum is private and its variants \
1425 cannot be re-exported"
1428 DiagnosticMessageId::ErrorId(0), // no code?!
1433 this.session.one_time_diagnostics.borrow_mut().insert(error_id);
1439 ref s @ _ => bug!("unexpected import subclass {:?}", s),
1441 let mut err = this.session.struct_span_err(binding.span, &msg);
1443 let imported_module = match directive.imported_module.get() {
1444 Some(ModuleOrUniformRoot::Module(module)) => module,
1445 _ => bug!("module should exist"),
1447 let parent_module = imported_module.parent.expect("parent should exist");
1448 let resolutions = this.resolutions(parent_module).borrow();
1449 let enum_path_segment_index = directive.module_path.len() - 1;
1450 let enum_ident = directive.module_path[enum_path_segment_index].ident;
1452 let key = this.new_key(enum_ident, TypeNS);
1453 let enum_resolution = resolutions.get(&key).expect("resolution should exist");
1455 enum_resolution.borrow().binding.expect("binding should exist").span;
1456 let enum_def_span = this.session.source_map().def_span(enum_span);
1457 let enum_def_snippet = this
1460 .span_to_snippet(enum_def_span)
1461 .expect("snippet should exist");
1462 // potentially need to strip extant `crate`/`pub(path)` for suggestion
1463 let after_vis_index = enum_def_snippet
1465 .expect("`enum` keyword should exist in snippet");
1466 let suggestion = format!("pub {}", &enum_def_snippet[after_vis_index..]);
1468 this.session.diag_span_suggestion_once(
1470 DiagnosticMessageId::ErrorId(0),
1472 "consider making the enum public",
1480 if reexports.len() > 0 {
1481 if let Some(def_id) = module.def_id() {
1482 self.r.export_map.insert(def_id, reexports);
1488 fn import_path_to_string(
1490 subclass: &ImportDirectiveSubclass<'_>,
1493 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1494 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1495 if let Some(pos) = pos {
1496 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1497 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1499 let names = if global { &names[1..] } else { names };
1500 if names.is_empty() {
1501 import_directive_subclass_to_string(subclass)
1505 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1506 import_directive_subclass_to_string(subclass),
1512 fn import_directive_subclass_to_string(subclass: &ImportDirectiveSubclass<'_>) -> String {
1514 SingleImport { source, .. } => source.to_string(),
1515 GlobImport { .. } => "*".to_string(),
1516 ExternCrate { .. } => "<extern crate>".to_string(),
1517 MacroUse => "#[macro_use]".to_string(),