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 rustc::hir::exports::Export;
15 use rustc::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
17 use rustc::{bug, span_bug};
18 use rustc_data_structures::fx::FxHashSet;
19 use rustc_data_structures::ptr_key::PtrKey;
20 use rustc_errors::{pluralize, struct_span_err, Applicability};
21 use rustc_hir::def::{self, PartialRes};
22 use rustc_hir::def_id::DefId;
23 use rustc_session::lint::BuiltinLintDiagnostics;
24 use rustc_session::DiagnosticMessageId;
25 use rustc_span::hygiene::ExpnId;
26 use rustc_span::symbol::kw;
27 use rustc_span::{MultiSpan, Span};
28 use syntax::ast::{Ident, Name, NodeId};
29 use syntax::unwrap_or;
30 use syntax::util::lev_distance::find_best_match_for_name;
37 type Res = def::Res<NodeId>;
39 /// Contains data for specific types of import directives.
40 #[derive(Clone, Debug)]
41 pub enum ImportDirectiveSubclass<'a> {
43 /// `source` in `use prefix::source as target`.
45 /// `target` in `use prefix::source as target`.
47 /// Bindings to which `source` refers to.
48 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
49 /// Bindings introduced by `target`.
50 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
51 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
53 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
58 max_vis: Cell<ty::Visibility>, // The visibility of the greatest re-export.
59 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
68 /// One import directive.
69 #[derive(Debug, Clone)]
70 crate struct ImportDirective<'a> {
71 /// The ID of the `extern crate`, `UseTree` etc that imported this `ImportDirective`.
73 /// In the case where the `ImportDirective` was expanded from a "nested" use tree,
74 /// this id is the ID of the leaf tree. For example:
76 /// ```ignore (pacify the mercilous tidy)
77 /// use foo::bar::{a, b}
80 /// If this is the import directive for `foo::bar::a`, we would have the ID of the `UseTree`
81 /// for `a` in this field.
84 /// The `id` of the "root" use-kind -- this is always the same as
85 /// `id` except in the case of "nested" use trees, in which case
86 /// it will be the `id` of the root use tree. e.g., in the example
87 /// from `id`, this would be the ID of the `use foo::bar`
91 /// Span of the entire use statement.
94 /// Span of the entire use statement with attributes.
95 pub use_span_with_attributes: Span,
97 /// Did the use statement have any attributes?
98 pub has_attributes: bool,
100 /// Span of this use tree.
103 /// Span of the *root* use tree (see `root_id`).
106 pub parent_scope: ParentScope<'a>,
107 pub module_path: Vec<Segment>,
108 /// The resolution of `module_path`.
109 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
110 pub subclass: ImportDirectiveSubclass<'a>,
111 pub vis: Cell<ty::Visibility>,
112 pub used: Cell<bool>,
115 impl<'a> ImportDirective<'a> {
116 pub fn is_glob(&self) -> bool {
117 match self.subclass {
118 ImportDirectiveSubclass::GlobImport { .. } => true,
123 pub fn is_nested(&self) -> bool {
124 match self.subclass {
125 ImportDirectiveSubclass::SingleImport { nested, .. } => nested,
130 crate fn crate_lint(&self) -> CrateLint {
131 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
135 #[derive(Clone, Default, Debug)]
136 /// Records information about the resolution of a name in a namespace of a module.
137 pub struct NameResolution<'a> {
138 /// Single imports that may define the name in the namespace.
139 /// Import directives are arena-allocated, so it's ok to use pointers as keys.
140 single_imports: FxHashSet<PtrKey<'a, ImportDirective<'a>>>,
141 /// The least shadowable known binding for this name, or None if there are no known bindings.
142 pub binding: Option<&'a NameBinding<'a>>,
143 shadowed_glob: Option<&'a NameBinding<'a>>,
146 impl<'a> NameResolution<'a> {
147 // Returns the binding for the name if it is known or None if it not known.
148 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
149 self.binding.and_then(|binding| {
150 if !binding.is_glob_import() || self.single_imports.is_empty() {
158 crate fn add_single_import(&mut self, directive: &'a ImportDirective<'a>) {
159 self.single_imports.insert(PtrKey(directive));
163 impl<'a> Resolver<'a> {
164 crate fn resolve_ident_in_module_unadjusted(
166 module: ModuleOrUniformRoot<'a>,
169 parent_scope: &ParentScope<'a>,
172 ) -> Result<&'a NameBinding<'a>, Determinacy> {
173 self.resolve_ident_in_module_unadjusted_ext(
182 .map_err(|(determinacy, _)| determinacy)
185 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
186 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
187 crate fn resolve_ident_in_module_unadjusted_ext(
189 module: ModuleOrUniformRoot<'a>,
192 parent_scope: &ParentScope<'a>,
193 restricted_shadowing: bool,
196 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
197 let module = match module {
198 ModuleOrUniformRoot::Module(module) => module,
199 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
200 assert!(!restricted_shadowing);
201 let binding = self.early_resolve_ident_in_lexical_scope(
203 ScopeSet::AbsolutePath(ns),
209 return binding.map_err(|determinacy| (determinacy, Weak::No));
211 ModuleOrUniformRoot::ExternPrelude => {
212 assert!(!restricted_shadowing);
213 return if ns != TypeNS {
214 Err((Determined, Weak::No))
215 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
217 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
218 // Macro-expanded `extern crate` items can add names to extern prelude.
219 Err((Undetermined, Weak::No))
221 Err((Determined, Weak::No))
224 ModuleOrUniformRoot::CurrentScope => {
225 assert!(!restricted_shadowing);
227 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
228 let module = self.resolve_crate_root(ident);
229 let binding = (module, ty::Visibility::Public, module.span, ExpnId::root())
230 .to_name_binding(self.arenas);
232 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
233 // FIXME: Implement these with renaming requirements so that e.g.
234 // `use super;` doesn't work, but `use super as name;` does.
235 // Fall through here to get an error from `early_resolve_...`.
239 let scopes = ScopeSet::All(ns, true);
240 let binding = self.early_resolve_ident_in_lexical_scope(
248 return binding.map_err(|determinacy| (determinacy, Weak::No));
252 let key = self.new_key(ident, ns);
254 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
256 if let Some(binding) = resolution.binding {
257 if !restricted_shadowing && binding.expansion != ExpnId::root() {
258 if let NameBindingKind::Res(_, true) = binding.kind {
259 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
264 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
265 if let Some(blacklisted_binding) = this.blacklisted_binding {
266 if ptr::eq(binding, blacklisted_binding) {
267 return Err((Determined, Weak::No));
270 // `extern crate` are always usable for backwards compatibility, see issue #37020,
271 // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
272 let usable = this.is_accessible_from(binding.vis, parent_scope.module)
273 || binding.is_extern_crate();
274 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
280 .and_then(|binding| {
281 // If the primary binding is blacklisted, search further and return the shadowed
282 // glob binding if it exists. What we really want here is having two separate
283 // scopes in a module - one for non-globs and one for globs, but until that's done
284 // use this hack to avoid inconsistent resolution ICEs during import validation.
285 if let Some(blacklisted_binding) = self.blacklisted_binding {
286 if ptr::eq(binding, blacklisted_binding) {
287 return resolution.shadowed_glob;
292 .ok_or((Determined, Weak::No))
293 .and_then(|binding| {
294 if self.last_import_segment && check_usable(self, binding).is_err() {
295 Err((Determined, Weak::No))
297 self.record_use(ident, ns, binding, restricted_shadowing);
299 if let Some(shadowed_glob) = resolution.shadowed_glob {
300 // Forbid expanded shadowing to avoid time travel.
301 if restricted_shadowing
302 && binding.expansion != ExpnId::root()
303 && binding.res() != shadowed_glob.res()
305 self.ambiguity_errors.push(AmbiguityError {
306 kind: AmbiguityKind::GlobVsExpanded,
310 misc1: AmbiguityErrorMisc::None,
311 misc2: AmbiguityErrorMisc::None,
316 if !self.is_accessible_from(binding.vis, parent_scope.module) &&
317 // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
318 !(self.last_import_segment && binding.is_extern_crate())
320 self.privacy_errors.push(PrivacyError {
323 dedup_span: path_span,
332 // Items and single imports are not shadowable, if we have one, then it's determined.
333 if let Some(binding) = resolution.binding {
334 if !binding.is_glob_import() {
335 return check_usable(self, binding);
339 // --- From now on we either have a glob resolution or no resolution. ---
341 // Check if one of single imports can still define the name,
342 // if it can then our result is not determined and can be invalidated.
343 for single_import in &resolution.single_imports {
344 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
347 let module = unwrap_or!(
348 single_import.imported_module.get(),
349 return Err((Undetermined, Weak::No))
351 let ident = match single_import.subclass {
352 SingleImport { source, .. } => source,
355 match self.resolve_ident_in_module(
359 &single_import.parent_scope,
363 Err(Determined) => continue,
365 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
369 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
373 // So we have a resolution that's from a glob import. This resolution is determined
374 // if it cannot be shadowed by some new item/import expanded from a macro.
375 // This happens either if there are no unexpanded macros, or expanded names cannot
376 // shadow globs (that happens in macro namespace or with restricted shadowing).
378 // Additionally, any macro in any module can plant names in the root module if it creates
379 // `macro_export` macros, so the root module effectively has unresolved invocations if any
380 // module has unresolved invocations.
381 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
382 // progress, we have to ignore those potential unresolved invocations from other modules
383 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
384 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
385 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
386 if let Some(binding) = resolution.binding {
387 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
388 return check_usable(self, binding);
390 return Err((Undetermined, Weak::No));
394 // --- From now on we have no resolution. ---
396 // Now we are in situation when new item/import can appear only from a glob or a macro
397 // expansion. With restricted shadowing names from globs and macro expansions cannot
398 // shadow names from outer scopes, so we can freely fallback from module search to search
399 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
400 // scopes we return `Undetermined` with `Weak::Yes`.
402 // Check if one of unexpanded macros can still define the name,
403 // if it can then our "no resolution" result is not determined and can be invalidated.
404 if unexpanded_macros {
405 return Err((Undetermined, Weak::Yes));
408 // Check if one of glob imports can still define the name,
409 // if it can then our "no resolution" result is not determined and can be invalidated.
410 for glob_import in module.globs.borrow().iter() {
411 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
414 let module = match glob_import.imported_module.get() {
415 Some(ModuleOrUniformRoot::Module(module)) => module,
417 None => return Err((Undetermined, Weak::Yes)),
419 let tmp_parent_scope;
420 let (mut adjusted_parent_scope, mut ident) = (parent_scope, ident.modern());
421 match ident.span.glob_adjust(module.expansion, glob_import.span) {
424 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
425 adjusted_parent_scope = &tmp_parent_scope;
430 let result = self.resolve_ident_in_module_unadjusted(
431 ModuleOrUniformRoot::Module(module),
434 adjusted_parent_scope,
440 Err(Determined) => continue,
442 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
446 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
450 // No resolution and no one else can define the name - determinate error.
451 Err((Determined, Weak::No))
454 // Given a binding and an import directive that resolves to it,
455 // return the corresponding binding defined by the import directive.
458 binding: &'a NameBinding<'a>,
459 directive: &'a ImportDirective<'a>,
460 ) -> &'a NameBinding<'a> {
461 let vis = if binding.pseudo_vis().is_at_least(directive.vis.get(), self) ||
462 // cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
463 !directive.is_glob() && binding.is_extern_crate()
470 if let GlobImport { ref max_vis, .. } = directive.subclass {
471 if vis == directive.vis.get() || vis.is_at_least(max_vis.get(), self) {
476 self.arenas.alloc_name_binding(NameBinding {
477 kind: NameBindingKind::Import { binding, directive, used: Cell::new(false) },
479 span: directive.span,
481 expansion: directive.parent_scope.expansion,
485 // Define the name or return the existing binding if there is a collision.
490 binding: &'a NameBinding<'a>,
491 ) -> Result<(), &'a NameBinding<'a>> {
492 let res = binding.res();
493 self.check_reserved_macro_name(key.ident, res);
494 self.set_binding_parent_module(binding, module);
495 self.update_resolution(module, key, |this, resolution| {
496 if let Some(old_binding) = resolution.binding {
498 // Do not override real bindings with `Res::Err`s from error recovery.
501 match (old_binding.is_glob_import(), binding.is_glob_import()) {
503 if res != old_binding.res() {
504 resolution.binding = Some(this.ambiguity(
505 AmbiguityKind::GlobVsGlob,
509 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
510 // We are glob-importing the same item but with greater visibility.
511 resolution.binding = Some(binding);
514 (old_glob @ true, false) | (old_glob @ false, true) => {
515 let (glob_binding, nonglob_binding) =
516 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
517 if glob_binding.res() != nonglob_binding.res()
519 && nonglob_binding.expansion != ExpnId::root()
521 resolution.binding = Some(this.ambiguity(
522 AmbiguityKind::GlobVsExpanded,
527 resolution.binding = Some(nonglob_binding);
529 resolution.shadowed_glob = Some(glob_binding);
532 return Err(old_binding);
536 resolution.binding = Some(binding);
546 primary_binding: &'a NameBinding<'a>,
547 secondary_binding: &'a NameBinding<'a>,
548 ) -> &'a NameBinding<'a> {
549 self.arenas.alloc_name_binding(NameBinding {
550 ambiguity: Some((secondary_binding, kind)),
551 ..primary_binding.clone()
555 // Use `f` to mutate the resolution of the name in the module.
556 // If the resolution becomes a success, define it in the module's glob importers.
557 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
559 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
561 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
562 // during which the resolution might end up getting re-defined via a glob cycle.
564 let resolution = &mut *self.resolution(module, key).borrow_mut();
565 let old_binding = resolution.binding();
567 let t = f(self, resolution);
569 match resolution.binding() {
570 _ if old_binding.is_some() => return t,
572 Some(binding) => match old_binding {
573 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
579 // Define `binding` in `module`s glob importers.
580 for directive in module.glob_importers.borrow_mut().iter() {
581 let mut ident = key.ident;
582 let scope = match ident.span.reverse_glob_adjust(module.expansion, directive.span) {
583 Some(Some(def)) => self.macro_def_scope(def),
584 Some(None) => directive.parent_scope.module,
587 if self.is_accessible_from(binding.vis, scope) {
588 let imported_binding = self.import(binding, directive);
589 let key = BindingKey { ident, ..key };
590 let _ = self.try_define(directive.parent_scope.module, key, imported_binding);
597 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
599 fn import_dummy_binding(&mut self, directive: &'a ImportDirective<'a>) {
600 if let SingleImport { target, .. } = directive.subclass {
601 let dummy_binding = self.dummy_binding;
602 let dummy_binding = self.import(dummy_binding, directive);
603 self.per_ns(|this, ns| {
604 let key = this.new_key(target, ns);
605 let _ = this.try_define(directive.parent_scope.module, key, dummy_binding);
606 // Consider erroneous imports used to avoid duplicate diagnostics.
607 this.record_use(target, ns, dummy_binding, false);
613 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
614 /// import errors within the same use tree into a single diagnostic.
615 #[derive(Debug, Clone)]
616 struct UnresolvedImportError {
618 label: Option<String>,
620 suggestion: Option<Suggestion>,
623 pub struct ImportResolver<'a, 'b> {
624 pub r: &'a mut Resolver<'b>,
627 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
628 fn parent(self, id: DefId) -> Option<DefId> {
633 impl<'a, 'b> ImportResolver<'a, 'b> {
636 // This is a fixed-point algorithm. We resolve imports until our efforts
637 // are stymied by an unresolved import; then we bail out of the current
638 // module and continue. We terminate successfully once no more imports
639 // remain or unsuccessfully when no forward progress in resolving imports
642 /// Resolves all imports for the crate. This method performs the fixed-
644 pub fn resolve_imports(&mut self) {
645 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
646 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
647 prev_num_indeterminates = self.r.indeterminate_imports.len();
648 for import in mem::take(&mut self.r.indeterminate_imports) {
649 match self.resolve_import(&import) {
650 true => self.r.determined_imports.push(import),
651 false => self.r.indeterminate_imports.push(import),
657 pub fn finalize_imports(&mut self) {
658 for module in self.r.arenas.local_modules().iter() {
659 self.finalize_resolutions_in(module);
662 let mut seen_spans = FxHashSet::default();
663 let mut errors = vec![];
664 let mut prev_root_id: NodeId = NodeId::from_u32(0);
665 let determined_imports = mem::take(&mut self.r.determined_imports);
666 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
668 for (is_indeterminate, import) in determined_imports
671 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
673 if let Some(err) = self.finalize_import(import) {
674 if let SingleImport { source, ref source_bindings, .. } = import.subclass {
675 if source.name == kw::SelfLower {
676 // Silence `unresolved import` error if E0429 is already emitted
677 if let Err(Determined) = source_bindings.value_ns.get() {
683 // If the error is a single failed import then create a "fake" import
684 // resolution for it so that later resolve stages won't complain.
685 self.r.import_dummy_binding(import);
686 if prev_root_id.as_u32() != 0
687 && prev_root_id.as_u32() != import.root_id.as_u32()
688 && !errors.is_empty()
690 // In the case of a new import line, throw a diagnostic message
691 // for the previous line.
692 self.throw_unresolved_import_error(errors, None);
695 if seen_spans.insert(err.span) {
696 let path = import_path_to_string(
697 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
701 errors.push((path, err));
702 prev_root_id = import.root_id;
704 } else if is_indeterminate {
705 // Consider erroneous imports used to avoid duplicate diagnostics.
706 self.r.used_imports.insert((import.id, TypeNS));
707 let path = import_path_to_string(
708 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
712 let err = UnresolvedImportError {
718 errors.push((path, err));
722 if !errors.is_empty() {
723 self.throw_unresolved_import_error(errors, None);
727 fn throw_unresolved_import_error(
729 errors: Vec<(String, UnresolvedImportError)>,
730 span: Option<MultiSpan>,
732 /// Upper limit on the number of `span_label` messages.
733 const MAX_LABEL_COUNT: usize = 10;
735 let (span, msg) = if errors.is_empty() {
736 (span.unwrap(), "unresolved import".to_string())
738 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
740 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
742 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
747 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
749 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
750 for message in note {
755 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
756 if let Some(label) = err.label {
757 diag.span_label(err.span, label);
760 if let Some((suggestions, msg, applicability)) = err.suggestion {
761 diag.multipart_suggestion(&msg, suggestions, applicability);
768 /// Attempts to resolve the given import, returning true if its resolution is determined.
769 /// If successful, the resolved bindings are written into the module.
770 fn resolve_import(&mut self, directive: &'b ImportDirective<'b>) -> bool {
772 "(resolving import for module) resolving import `{}::...` in `{}`",
773 Segment::names_to_string(&directive.module_path),
774 module_to_string(directive.parent_scope.module).unwrap_or_else(|| "???".to_string()),
777 let module = if let Some(module) = directive.imported_module.get() {
780 // For better failure detection, pretend that the import will
781 // not define any names while resolving its module path.
782 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
783 let path_res = self.r.resolve_path(
784 &directive.module_path,
786 &directive.parent_scope,
789 directive.crate_lint(),
791 directive.vis.set(orig_vis);
794 PathResult::Module(module) => module,
795 PathResult::Indeterminate => return false,
796 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
800 directive.imported_module.set(Some(module));
801 let (source, target, source_bindings, target_bindings, type_ns_only) =
802 match directive.subclass {
810 } => (source, target, source_bindings, target_bindings, type_ns_only),
811 GlobImport { .. } => {
812 self.resolve_glob_import(directive);
818 let mut indeterminate = false;
819 self.r.per_ns(|this, ns| {
820 if !type_ns_only || ns == TypeNS {
821 if let Err(Undetermined) = source_bindings[ns].get() {
822 // For better failure detection, pretend that the import will
823 // not define any names while resolving its module path.
824 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
825 let binding = this.resolve_ident_in_module(
829 &directive.parent_scope,
833 directive.vis.set(orig_vis);
835 source_bindings[ns].set(binding);
840 let parent = directive.parent_scope.module;
841 match source_bindings[ns].get() {
842 Err(Undetermined) => indeterminate = true,
843 // Don't update the resolution, because it was never added.
844 Err(Determined) if target.name == kw::Underscore => {}
846 let key = this.new_key(target, ns);
847 this.update_resolution(parent, key, |_, resolution| {
848 resolution.single_imports.remove(&PtrKey(directive));
851 Ok(binding) if !binding.is_importable() => {
852 let msg = format!("`{}` is not directly importable", target);
853 struct_span_err!(this.session, directive.span, E0253, "{}", &msg)
854 .span_label(directive.span, "cannot be imported directly")
856 // Do not import this illegal binding. Import a dummy binding and pretend
857 // everything is fine
858 this.import_dummy_binding(directive);
861 let imported_binding = this.import(binding, directive);
862 target_bindings[ns].set(Some(imported_binding));
863 this.define(parent, target, ns, imported_binding);
872 /// Performs final import resolution, consistency checks and error reporting.
874 /// Optionally returns an unresolved import error. This error is buffered and used to
875 /// consolidate multiple unresolved import errors into a single diagnostic.
878 directive: &'b ImportDirective<'b>,
879 ) -> Option<UnresolvedImportError> {
880 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
881 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
882 let path_res = self.r.resolve_path(
883 &directive.module_path,
885 &directive.parent_scope,
888 directive.crate_lint(),
890 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
891 directive.vis.set(orig_vis);
892 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
893 // Consider erroneous imports used to avoid duplicate diagnostics.
894 self.r.used_imports.insert((directive.id, TypeNS));
896 let module = match path_res {
897 PathResult::Module(module) => {
898 // Consistency checks, analogous to `finalize_macro_resolutions`.
899 if let Some(initial_module) = directive.imported_module.get() {
900 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
901 span_bug!(directive.span, "inconsistent resolution for an import");
904 if self.r.privacy_errors.is_empty() {
905 let msg = "cannot determine resolution for the import";
906 let msg_note = "import resolution is stuck, try simplifying other imports";
907 self.r.session.struct_span_err(directive.span, msg).note(msg_note).emit();
913 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
915 assert!(directive.imported_module.get().is_none());
917 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
921 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
923 assert!(directive.imported_module.get().is_none());
924 let err = match self.make_path_suggestion(
926 directive.module_path.clone(),
927 &directive.parent_scope,
929 Some((suggestion, note)) => UnresolvedImportError {
934 vec![(span, Segment::names_to_string(&suggestion))],
935 String::from("a similar path exists"),
936 Applicability::MaybeIncorrect,
939 None => UnresolvedImportError {
950 PathResult::NonModule(path_res) if path_res.base_res() == Res::Err => {
952 assert!(directive.imported_module.get().is_none());
954 // The error was already reported earlier.
957 PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(),
960 let (ident, target, source_bindings, target_bindings, type_ns_only) = match directive
970 } => (source, target, source_bindings, target_bindings, type_ns_only),
971 GlobImport { is_prelude, ref max_vis } => {
972 if directive.module_path.len() <= 1 {
973 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
974 // 2 segments, so the `resolve_path` above won't trigger it.
975 let mut full_path = directive.module_path.clone();
976 full_path.push(Segment::from_ident(Ident::invalid()));
977 self.r.lint_if_path_starts_with_module(
978 directive.crate_lint(),
985 if let ModuleOrUniformRoot::Module(module) = module {
986 if module.def_id() == directive.parent_scope.module.def_id() {
987 // Importing a module into itself is not allowed.
988 return Some(UnresolvedImportError {
989 span: directive.span,
990 label: Some(String::from("cannot glob-import a module into itself")),
997 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
998 !max_vis.get().is_at_least(directive.vis.get(), &*self)
1000 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1001 self.r.lint_buffer.buffer_lint(
1010 _ => unreachable!(),
1013 let mut all_ns_err = true;
1014 self.r.per_ns(|this, ns| {
1015 if !type_ns_only || ns == TypeNS {
1016 let orig_vis = directive.vis.replace(ty::Visibility::Invisible);
1017 let orig_blacklisted_binding =
1018 mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get());
1019 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1020 let binding = this.resolve_ident_in_module(
1024 &directive.parent_scope,
1028 this.last_import_segment = orig_last_import_segment;
1029 this.blacklisted_binding = orig_blacklisted_binding;
1030 directive.vis.set(orig_vis);
1034 // Consistency checks, analogous to `finalize_macro_resolutions`.
1035 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1037 if let Some(target_binding) = target_bindings[ns].get() {
1038 // Note that as_str() de-gensyms the Symbol
1039 if target.name.as_str() == "_"
1040 && initial_binding.is_extern_crate()
1041 && !initial_binding.is_import()
1047 directive.module_path.is_empty(),
1051 initial_binding.res()
1053 let res = binding.res();
1054 if let Ok(initial_res) = initial_res {
1055 if res != initial_res && this.ambiguity_errors.is_empty() {
1056 span_bug!(directive.span, "inconsistent resolution for an import");
1060 && this.ambiguity_errors.is_empty()
1061 && this.privacy_errors.is_empty()
1063 let msg = "cannot determine resolution for the import";
1065 "import resolution is stuck, try simplifying other imports";
1067 .struct_span_err(directive.span, msg)
1074 // FIXME: This assert may fire if public glob is later shadowed by a private
1075 // single import (see test `issue-55884-2.rs`). In theory single imports should
1076 // always block globs, even if they are not yet resolved, so that this kind of
1077 // self-inconsistent resolution never happens.
1078 // Reenable the assert when the issue is fixed.
1079 // assert!(result[ns].get().is_err());
1086 let mut all_ns_failed = true;
1087 self.r.per_ns(|this, ns| {
1088 if !type_ns_only || ns == TypeNS {
1089 let binding = this.resolve_ident_in_module(
1093 &directive.parent_scope,
1097 if binding.is_ok() {
1098 all_ns_failed = false;
1103 return if all_ns_failed {
1104 let resolutions = match module {
1105 ModuleOrUniformRoot::Module(module) => {
1106 Some(self.r.resolutions(module).borrow())
1110 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1111 let names = resolutions.filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1114 } // Never suggest the same name
1115 match *resolution.borrow() {
1116 NameResolution { binding: Some(name_binding), .. } => {
1117 match name_binding.kind {
1118 NameBindingKind::Import { binding, .. } => {
1119 match binding.kind {
1120 // Never suggest the name that has binding error
1121 // i.e., the name that cannot be previously resolved
1122 NameBindingKind::Res(Res::Err, _) => return None,
1129 NameResolution { ref single_imports, .. } if single_imports.is_empty() => {
1136 let lev_suggestion =
1137 find_best_match_for_name(names, &ident.as_str(), None).map(|suggestion| {
1139 vec![(ident.span, suggestion.to_string())],
1140 String::from("a similar name exists in the module"),
1141 Applicability::MaybeIncorrect,
1145 let (suggestion, note) =
1146 match self.check_for_module_export_macro(directive, module, ident) {
1147 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
1148 _ => (lev_suggestion, Vec::new()),
1151 let label = match module {
1152 ModuleOrUniformRoot::Module(module) => {
1153 let module_str = module_to_string(module);
1154 if let Some(module_str) = module_str {
1155 format!("no `{}` in `{}`", ident, module_str)
1157 format!("no `{}` in the root", ident)
1161 if !ident.is_path_segment_keyword() {
1162 format!("no `{}` external crate", ident)
1164 // HACK(eddyb) this shows up for `self` & `super`, which
1165 // should work instead - for now keep the same error message.
1166 format!("no `{}` in the root", ident)
1171 Some(UnresolvedImportError {
1172 span: directive.span,
1178 // `resolve_ident_in_module` reported a privacy error.
1179 self.r.import_dummy_binding(directive);
1184 let mut reexport_error = None;
1185 let mut any_successful_reexport = false;
1186 self.r.per_ns(|this, ns| {
1187 if let Ok(binding) = source_bindings[ns].get() {
1188 let vis = directive.vis.get();
1189 if !binding.pseudo_vis().is_at_least(vis, &*this) {
1190 reexport_error = Some((ns, binding));
1192 any_successful_reexport = true;
1197 // All namespaces must be re-exported with extra visibility for an error to occur.
1198 if !any_successful_reexport {
1199 let (ns, binding) = reexport_error.unwrap();
1200 if ns == TypeNS && binding.is_extern_crate() {
1202 "extern crate `{}` is private, and cannot be \
1203 re-exported (error E0365), consider declaring with \
1207 self.r.lint_buffer.buffer_lint(
1208 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1213 } else if ns == TypeNS {
1218 "`{}` is private, and cannot be re-exported",
1221 .span_label(directive.span, format!("re-export of private `{}`", ident))
1222 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1225 let msg = format!("`{}` is private, and cannot be re-exported", ident);
1227 format!("consider marking `{}` as `pub` in the imported module", ident,);
1228 struct_span_err!(self.r.session, directive.span, E0364, "{}", &msg)
1229 .span_note(directive.span, ¬e_msg)
1234 if directive.module_path.len() <= 1 {
1235 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1236 // 2 segments, so the `resolve_path` above won't trigger it.
1237 let mut full_path = directive.module_path.clone();
1238 full_path.push(Segment::from_ident(ident));
1239 self.r.per_ns(|this, ns| {
1240 if let Ok(binding) = source_bindings[ns].get() {
1241 this.lint_if_path_starts_with_module(
1242 directive.crate_lint(),
1251 // Record what this import resolves to for later uses in documentation,
1252 // this may resolve to either a value or a type, but for documentation
1253 // purposes it's good enough to just favor one over the other.
1254 self.r.per_ns(|this, ns| {
1255 if let Some(binding) = source_bindings[ns].get().ok() {
1256 this.import_res_map.entry(directive.id).or_default()[ns] = Some(binding.res());
1260 self.check_for_redundant_imports(
1268 debug!("(resolving single import) successfully resolved import");
1272 fn check_for_redundant_imports(
1275 directive: &'b ImportDirective<'b>,
1276 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1277 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1280 // Skip if the import was produced by a macro.
1281 if directive.parent_scope.expansion != ExpnId::root() {
1285 // Skip if we are inside a named module (in contrast to an anonymous
1286 // module defined by a block).
1287 if let ModuleKind::Def(..) = directive.parent_scope.module.kind {
1291 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1293 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1295 self.r.per_ns(|this, ns| {
1296 if let Some(binding) = source_bindings[ns].get().ok() {
1297 if binding.res() == Res::Err {
1301 let orig_blacklisted_binding =
1302 mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get());
1304 match this.early_resolve_ident_in_lexical_scope(
1306 ScopeSet::All(ns, false),
1307 &directive.parent_scope,
1312 Ok(other_binding) => {
1313 is_redundant[ns] = Some(
1314 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1316 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1318 Err(_) => is_redundant[ns] = Some(false),
1321 this.blacklisted_binding = orig_blacklisted_binding;
1325 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1327 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1328 redundant_spans.sort();
1329 redundant_spans.dedup();
1330 self.r.lint_buffer.buffer_lint_with_diagnostic(
1334 &format!("the item `{}` is imported redundantly", ident),
1335 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1340 fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) {
1341 let module = match directive.imported_module.get().unwrap() {
1342 ModuleOrUniformRoot::Module(module) => module,
1344 self.r.session.span_err(directive.span, "cannot glob-import all possible crates");
1349 if module.is_trait() {
1350 self.r.session.span_err(directive.span, "items in traits are not importable.");
1352 } else if module.def_id() == directive.parent_scope.module.def_id() {
1354 } else if let GlobImport { is_prelude: true, .. } = directive.subclass {
1355 self.r.prelude = Some(module);
1359 // Add to module's glob_importers
1360 module.glob_importers.borrow_mut().push(directive);
1362 // Ensure that `resolutions` isn't borrowed during `try_define`,
1363 // since it might get updated via a glob cycle.
1366 .resolutions(module)
1369 .filter_map(|(key, resolution)| {
1370 resolution.borrow().binding().map(|binding| (*key, binding))
1372 .collect::<Vec<_>>();
1373 for (mut key, binding) in bindings {
1374 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, directive.span) {
1375 Some(Some(def)) => self.r.macro_def_scope(def),
1376 Some(None) => directive.parent_scope.module,
1379 if self.r.is_accessible_from(binding.pseudo_vis(), scope) {
1380 let imported_binding = self.r.import(binding, directive);
1381 let _ = self.r.try_define(directive.parent_scope.module, key, imported_binding);
1385 // Record the destination of this import
1386 self.r.record_partial_res(directive.id, PartialRes::new(module.res().unwrap()));
1389 // Miscellaneous post-processing, including recording re-exports,
1390 // reporting conflicts, and reporting unresolved imports.
1391 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1392 // Since import resolution is finished, globs will not define any more names.
1393 *module.globs.borrow_mut() = Vec::new();
1395 let mut reexports = Vec::new();
1397 module.for_each_child(self.r, |this, ident, ns, binding| {
1398 // Filter away ambiguous imports and anything that has def-site
1400 // FIXME: Implement actual cross-crate hygiene.
1401 let is_good_import =
1402 binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
1403 if is_good_import || binding.is_macro_def() {
1404 let res = binding.res();
1405 if res != Res::Err {
1406 if let Some(def_id) = res.opt_def_id() {
1407 if !def_id.is_local() {
1408 this.cstore().export_macros_untracked(def_id.krate);
1411 reexports.push(Export { ident, res, span: binding.span, vis: binding.vis });
1415 if let NameBindingKind::Import { binding: orig_binding, directive, .. } = binding.kind {
1417 && orig_binding.is_variant()
1418 && !orig_binding.vis.is_at_least(binding.vis, &*this)
1420 let msg = match directive.subclass {
1421 ImportDirectiveSubclass::SingleImport { .. } => {
1422 format!("variant `{}` is private and cannot be re-exported", ident)
1424 ImportDirectiveSubclass::GlobImport { .. } => {
1425 let msg = "enum is private and its variants \
1426 cannot be re-exported"
1429 DiagnosticMessageId::ErrorId(0), // no code?!
1434 this.session.one_time_diagnostics.borrow_mut().insert(error_id);
1440 ref s @ _ => bug!("unexpected import subclass {:?}", s),
1442 let mut err = this.session.struct_span_err(binding.span, &msg);
1444 let imported_module = match directive.imported_module.get() {
1445 Some(ModuleOrUniformRoot::Module(module)) => module,
1446 _ => bug!("module should exist"),
1448 let parent_module = imported_module.parent.expect("parent should exist");
1449 let resolutions = this.resolutions(parent_module).borrow();
1450 let enum_path_segment_index = directive.module_path.len() - 1;
1451 let enum_ident = directive.module_path[enum_path_segment_index].ident;
1453 let key = this.new_key(enum_ident, TypeNS);
1454 let enum_resolution = resolutions.get(&key).expect("resolution should exist");
1456 enum_resolution.borrow().binding.expect("binding should exist").span;
1457 let enum_def_span = this.session.source_map().def_span(enum_span);
1458 let enum_def_snippet = this
1461 .span_to_snippet(enum_def_span)
1462 .expect("snippet should exist");
1463 // potentially need to strip extant `crate`/`pub(path)` for suggestion
1464 let after_vis_index = enum_def_snippet
1466 .expect("`enum` keyword should exist in snippet");
1467 let suggestion = format!("pub {}", &enum_def_snippet[after_vis_index..]);
1469 this.session.diag_span_suggestion_once(
1471 DiagnosticMessageId::ErrorId(0),
1473 "consider making the enum public",
1481 if reexports.len() > 0 {
1482 if let Some(def_id) = module.def_id() {
1483 self.r.export_map.insert(def_id, reexports);
1489 fn import_path_to_string(
1491 subclass: &ImportDirectiveSubclass<'_>,
1494 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1495 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1496 if let Some(pos) = pos {
1497 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1498 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1500 let names = if global { &names[1..] } else { names };
1501 if names.is_empty() {
1502 import_directive_subclass_to_string(subclass)
1506 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1507 import_directive_subclass_to_string(subclass),
1513 fn import_directive_subclass_to_string(subclass: &ImportDirectiveSubclass<'_>) -> String {
1515 SingleImport { source, .. } => source.to_string(),
1516 GlobImport { .. } => "*".to_string(),
1517 ExternCrate { .. } => "<extern crate>".to_string(),
1518 MacroUse => "#[macro_use]".to_string(),