1 //! A bunch of methods and structures more or less related to resolving imports.
3 use crate::diagnostics::Suggestion;
4 use crate::Determinacy::{self, *};
5 use crate::Namespace::{self, MacroNS, TypeNS};
6 use crate::{module_to_string, names_to_string};
7 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
8 use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
9 use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak};
10 use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
12 use rustc_ast::NodeId;
13 use rustc_data_structures::fx::FxHashSet;
14 use rustc_data_structures::intern::Interned;
15 use rustc_errors::{pluralize, struct_span_err, Applicability};
16 use rustc_hir::def::{self, PartialRes};
17 use rustc_hir::def_id::DefId;
18 use rustc_middle::metadata::ModChild;
19 use rustc_middle::span_bug;
21 use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
22 use rustc_session::lint::BuiltinLintDiagnostics;
23 use rustc_span::hygiene::LocalExpnId;
24 use rustc_span::lev_distance::find_best_match_for_name;
25 use rustc_span::symbol::{kw, Ident, Symbol};
26 use rustc_span::{MultiSpan, Span};
33 type Res = def::Res<NodeId>;
35 /// Contains data for specific kinds of imports.
36 #[derive(Clone, Debug)]
37 pub enum ImportKind<'a> {
39 /// `source` in `use prefix::source as target`.
41 /// `target` in `use prefix::source as target`.
43 /// Bindings to which `source` refers to.
44 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
45 /// Bindings introduced by `target`.
46 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
47 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
49 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
51 /// Additional `NodeId`s allocated to a `ast::UseTree` for automatically generated `use` statement
52 /// (eg. implicit struct constructors)
53 additional_ids: (NodeId, NodeId),
57 max_vis: Cell<ty::Visibility>, // The visibility of the greatest re-export.
58 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
61 source: Option<Symbol>,
68 #[derive(Debug, Clone)]
69 crate struct Import<'a> {
70 pub kind: ImportKind<'a>,
72 /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`.
74 /// In the case where the `Import` was expanded from a "nested" use tree,
75 /// this id is the ID of the leaf tree. For example:
77 /// ```ignore (pacify the mercilous tidy)
78 /// use foo::bar::{a, b}
81 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
82 /// for `a` in this field.
85 /// The `id` of the "root" use-kind -- this is always the same as
86 /// `id` except in the case of "nested" use trees, in which case
87 /// it will be the `id` of the root use tree. e.g., in the example
88 /// from `id`, this would be the ID of the `use foo::bar`
92 /// Span of the entire use statement.
95 /// Span of the entire use statement with attributes.
96 pub use_span_with_attributes: Span,
98 /// Did the use statement have any attributes?
99 pub has_attributes: bool,
101 /// Span of this use tree.
104 /// Span of the *root* use tree (see `root_id`).
107 pub parent_scope: ParentScope<'a>,
108 pub module_path: Vec<Segment>,
109 /// The resolution of `module_path`.
110 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
111 pub vis: Cell<ty::Visibility>,
112 pub used: Cell<bool>,
115 impl<'a> Import<'a> {
116 pub fn is_glob(&self) -> bool {
117 matches!(self.kind, ImportKind::Glob { .. })
120 pub fn is_nested(&self) -> bool {
122 ImportKind::Single { nested, .. } => nested,
127 crate fn crate_lint(&self) -> CrateLint {
128 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
132 #[derive(Clone, Default, Debug)]
133 /// Records information about the resolution of a name in a namespace of a module.
134 pub struct NameResolution<'a> {
135 /// Single imports that may define the name in the namespace.
136 /// Imports are arena-allocated, so it's ok to use pointers as keys.
137 single_imports: FxHashSet<Interned<'a, Import<'a>>>,
138 /// The least shadowable known binding for this name, or None if there are no known bindings.
139 pub binding: Option<&'a NameBinding<'a>>,
140 shadowed_glob: Option<&'a NameBinding<'a>>,
143 impl<'a> NameResolution<'a> {
144 // Returns the binding for the name if it is known or None if it not known.
145 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
146 self.binding.and_then(|binding| {
147 if !binding.is_glob_import() || self.single_imports.is_empty() {
155 crate fn add_single_import(&mut self, import: &'a Import<'a>) {
156 self.single_imports.insert(Interned::new_unchecked(import));
160 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
161 // are permitted for backward-compatibility under a deprecation lint.
162 fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
163 match (&import.kind, &binding.kind) {
165 ImportKind::Single { .. },
166 NameBindingKind::Import {
167 import: Import { kind: ImportKind::ExternCrate { .. }, .. },
170 ) => import.vis.get().is_public(),
175 impl<'a> Resolver<'a> {
176 crate fn resolve_ident_in_module_unadjusted(
178 module: ModuleOrUniformRoot<'a>,
181 parent_scope: &ParentScope<'a>,
184 ) -> Result<&'a NameBinding<'a>, Determinacy> {
185 self.resolve_ident_in_module_unadjusted_ext(
194 .map_err(|(determinacy, _)| determinacy)
197 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
198 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
199 crate fn resolve_ident_in_module_unadjusted_ext(
201 module: ModuleOrUniformRoot<'a>,
204 parent_scope: &ParentScope<'a>,
205 restricted_shadowing: bool,
208 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
209 let module = match module {
210 ModuleOrUniformRoot::Module(module) => module,
211 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
212 assert!(!restricted_shadowing);
213 let binding = self.early_resolve_ident_in_lexical_scope(
215 ScopeSet::AbsolutePath(ns),
221 return binding.map_err(|determinacy| (determinacy, Weak::No));
223 ModuleOrUniformRoot::ExternPrelude => {
224 assert!(!restricted_shadowing);
225 return if ns != TypeNS {
226 Err((Determined, Weak::No))
227 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
229 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
230 // Macro-expanded `extern crate` items can add names to extern prelude.
231 Err((Undetermined, Weak::No))
233 Err((Determined, Weak::No))
236 ModuleOrUniformRoot::CurrentScope => {
237 assert!(!restricted_shadowing);
239 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
240 let module = self.resolve_crate_root(ident);
242 (module, ty::Visibility::Public, module.span, LocalExpnId::ROOT)
243 .to_name_binding(self.arenas);
245 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
246 // FIXME: Implement these with renaming requirements so that e.g.
247 // `use super;` doesn't work, but `use super as name;` does.
248 // Fall through here to get an error from `early_resolve_...`.
252 let scopes = ScopeSet::All(ns, true);
253 let binding = self.early_resolve_ident_in_lexical_scope(
261 return binding.map_err(|determinacy| (determinacy, Weak::No));
265 let key = self.new_key(ident, ns);
267 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
269 if let Some(binding) = resolution.binding {
270 if !restricted_shadowing && binding.expansion != LocalExpnId::ROOT {
271 if let NameBindingKind::Res(_, true) = binding.kind {
272 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
277 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
278 if let Some(unusable_binding) = this.unusable_binding {
279 if ptr::eq(binding, unusable_binding) {
280 return Err((Determined, Weak::No));
283 let usable = this.is_accessible_from(binding.vis, parent_scope.module);
284 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
290 .and_then(|binding| {
291 // If the primary binding is unusable, search further and return the shadowed glob
292 // binding if it exists. What we really want here is having two separate scopes in
293 // a module - one for non-globs and one for globs, but until that's done use this
294 // hack to avoid inconsistent resolution ICEs during import validation.
295 if let Some(unusable_binding) = self.unusable_binding {
296 if ptr::eq(binding, unusable_binding) {
297 return resolution.shadowed_glob;
302 .ok_or((Determined, Weak::No))
303 .and_then(|binding| {
304 if self.last_import_segment && check_usable(self, binding).is_err() {
305 Err((Determined, Weak::No))
307 self.record_use(ident, binding, restricted_shadowing);
309 if let Some(shadowed_glob) = resolution.shadowed_glob {
310 // Forbid expanded shadowing to avoid time travel.
311 if restricted_shadowing
312 && binding.expansion != LocalExpnId::ROOT
313 && binding.res() != shadowed_glob.res()
315 self.ambiguity_errors.push(AmbiguityError {
316 kind: AmbiguityKind::GlobVsExpanded,
320 misc1: AmbiguityErrorMisc::None,
321 misc2: AmbiguityErrorMisc::None,
326 if !self.is_accessible_from(binding.vis, parent_scope.module) {
327 self.privacy_errors.push(PrivacyError {
330 dedup_span: path_span,
339 // Items and single imports are not shadowable, if we have one, then it's determined.
340 if let Some(binding) = resolution.binding {
341 if !binding.is_glob_import() {
342 return check_usable(self, binding);
346 // --- From now on we either have a glob resolution or no resolution. ---
348 // Check if one of single imports can still define the name,
349 // if it can then our result is not determined and can be invalidated.
350 for single_import in &resolution.single_imports {
351 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
354 let Some(module) = single_import.imported_module.get() else {
355 return Err((Undetermined, Weak::No));
357 let ImportKind::Single { source: ident, .. } = single_import.kind else {
360 match self.resolve_ident_in_module(
364 &single_import.parent_scope,
368 Err(Determined) => continue,
370 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
374 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
378 // So we have a resolution that's from a glob import. This resolution is determined
379 // if it cannot be shadowed by some new item/import expanded from a macro.
380 // This happens either if there are no unexpanded macros, or expanded names cannot
381 // shadow globs (that happens in macro namespace or with restricted shadowing).
383 // Additionally, any macro in any module can plant names in the root module if it creates
384 // `macro_export` macros, so the root module effectively has unresolved invocations if any
385 // module has unresolved invocations.
386 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
387 // progress, we have to ignore those potential unresolved invocations from other modules
388 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
389 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
390 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
391 if let Some(binding) = resolution.binding {
392 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
393 return check_usable(self, binding);
395 return Err((Undetermined, Weak::No));
399 // --- From now on we have no resolution. ---
401 // Now we are in situation when new item/import can appear only from a glob or a macro
402 // expansion. With restricted shadowing names from globs and macro expansions cannot
403 // shadow names from outer scopes, so we can freely fallback from module search to search
404 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
405 // scopes we return `Undetermined` with `Weak::Yes`.
407 // Check if one of unexpanded macros can still define the name,
408 // if it can then our "no resolution" result is not determined and can be invalidated.
409 if unexpanded_macros {
410 return Err((Undetermined, Weak::Yes));
413 // Check if one of glob imports can still define the name,
414 // if it can then our "no resolution" result is not determined and can be invalidated.
415 for glob_import in module.globs.borrow().iter() {
416 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
419 let module = match glob_import.imported_module.get() {
420 Some(ModuleOrUniformRoot::Module(module)) => module,
422 None => return Err((Undetermined, Weak::Yes)),
424 let tmp_parent_scope;
425 let (mut adjusted_parent_scope, mut ident) =
426 (parent_scope, ident.normalize_to_macros_2_0());
427 match ident.span.glob_adjust(module.expansion, glob_import.span) {
430 ParentScope { module: self.expn_def_scope(def), ..*parent_scope };
431 adjusted_parent_scope = &tmp_parent_scope;
436 let result = self.resolve_ident_in_module_unadjusted(
437 ModuleOrUniformRoot::Module(module),
440 adjusted_parent_scope,
446 Err(Determined) => continue,
448 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
452 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
456 // No resolution and no one else can define the name - determinate error.
457 Err((Determined, Weak::No))
460 // Given a binding and an import that resolves to it,
461 // return the corresponding binding defined by the import.
464 binding: &'a NameBinding<'a>,
465 import: &'a Import<'a>,
466 ) -> &'a NameBinding<'a> {
467 let vis = if binding.vis.is_at_least(import.vis.get(), self)
468 || pub_use_of_private_extern_crate_hack(import, binding)
475 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
476 if vis == import.vis.get() || vis.is_at_least(max_vis.get(), self) {
481 self.arenas.alloc_name_binding(NameBinding {
482 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
486 expansion: import.parent_scope.expansion,
490 // Define the name or return the existing binding if there is a collision.
495 binding: &'a NameBinding<'a>,
496 ) -> Result<(), &'a NameBinding<'a>> {
497 let res = binding.res();
498 self.check_reserved_macro_name(key.ident, res);
499 self.set_binding_parent_module(binding, module);
500 self.update_resolution(module, key, |this, resolution| {
501 if let Some(old_binding) = resolution.binding {
503 // Do not override real bindings with `Res::Err`s from error recovery.
506 match (old_binding.is_glob_import(), binding.is_glob_import()) {
508 if res != old_binding.res() {
509 resolution.binding = Some(this.ambiguity(
510 AmbiguityKind::GlobVsGlob,
514 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
515 // We are glob-importing the same item but with greater visibility.
516 resolution.binding = Some(binding);
519 (old_glob @ true, false) | (old_glob @ false, true) => {
520 let (glob_binding, nonglob_binding) =
521 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
522 if glob_binding.res() != nonglob_binding.res()
524 && nonglob_binding.expansion != LocalExpnId::ROOT
526 resolution.binding = Some(this.ambiguity(
527 AmbiguityKind::GlobVsExpanded,
532 resolution.binding = Some(nonglob_binding);
534 resolution.shadowed_glob = Some(glob_binding);
537 return Err(old_binding);
541 resolution.binding = Some(binding);
551 primary_binding: &'a NameBinding<'a>,
552 secondary_binding: &'a NameBinding<'a>,
553 ) -> &'a NameBinding<'a> {
554 self.arenas.alloc_name_binding(NameBinding {
555 ambiguity: Some((secondary_binding, kind)),
556 ..primary_binding.clone()
560 // Use `f` to mutate the resolution of the name in the module.
561 // If the resolution becomes a success, define it in the module's glob importers.
562 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
564 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
566 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
567 // during which the resolution might end up getting re-defined via a glob cycle.
569 let resolution = &mut *self.resolution(module, key).borrow_mut();
570 let old_binding = resolution.binding();
572 let t = f(self, resolution);
574 match resolution.binding() {
575 _ if old_binding.is_some() => return t,
577 Some(binding) => match old_binding {
578 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
584 // Define `binding` in `module`s glob importers.
585 for import in module.glob_importers.borrow_mut().iter() {
586 let mut ident = key.ident;
587 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
588 Some(Some(def)) => self.expn_def_scope(def),
589 Some(None) => import.parent_scope.module,
592 if self.is_accessible_from(binding.vis, scope) {
593 let imported_binding = self.import(binding, import);
594 let key = BindingKey { ident, ..key };
595 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
602 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
604 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
605 if let ImportKind::Single { target, .. } = import.kind {
606 let dummy_binding = self.dummy_binding;
607 let dummy_binding = self.import(dummy_binding, import);
608 self.per_ns(|this, ns| {
609 let key = this.new_key(target, ns);
610 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
612 // Consider erroneous imports used to avoid duplicate diagnostics.
613 self.record_use(target, dummy_binding, false);
618 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
619 /// import errors within the same use tree into a single diagnostic.
620 #[derive(Debug, Clone)]
621 struct UnresolvedImportError {
623 label: Option<String>,
625 suggestion: Option<Suggestion>,
628 pub struct ImportResolver<'a, 'b> {
629 pub r: &'a mut Resolver<'b>,
632 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
633 fn parent(self, id: DefId) -> Option<DefId> {
638 impl<'a, 'b> ImportResolver<'a, 'b> {
641 // This is a fixed-point algorithm. We resolve imports until our efforts
642 // are stymied by an unresolved import; then we bail out of the current
643 // module and continue. We terminate successfully once no more imports
644 // remain or unsuccessfully when no forward progress in resolving imports
647 /// Resolves all imports for the crate. This method performs the fixed-
649 pub fn resolve_imports(&mut self) {
650 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
651 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
652 prev_num_indeterminates = self.r.indeterminate_imports.len();
653 for import in mem::take(&mut self.r.indeterminate_imports) {
654 match self.resolve_import(&import) {
655 true => self.r.determined_imports.push(import),
656 false => self.r.indeterminate_imports.push(import),
662 pub fn finalize_imports(&mut self) {
663 for module in self.r.arenas.local_modules().iter() {
664 self.finalize_resolutions_in(module);
667 let mut seen_spans = FxHashSet::default();
668 let mut errors = vec![];
669 let mut prev_root_id: NodeId = NodeId::from_u32(0);
670 let determined_imports = mem::take(&mut self.r.determined_imports);
671 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
673 for (is_indeterminate, import) in determined_imports
676 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
678 if let Some(err) = self.finalize_import(import) {
679 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
680 if source.name == kw::SelfLower {
681 // Silence `unresolved import` error if E0429 is already emitted
682 if let Err(Determined) = source_bindings.value_ns.get() {
688 // If the error is a single failed import then create a "fake" import
689 // resolution for it so that later resolve stages won't complain.
690 self.r.import_dummy_binding(import);
691 if prev_root_id.as_u32() != 0
692 && prev_root_id.as_u32() != import.root_id.as_u32()
693 && !errors.is_empty()
695 // In the case of a new import line, throw a diagnostic message
696 // for the previous line.
697 self.throw_unresolved_import_error(errors, None);
700 if seen_spans.insert(err.span) {
701 let path = import_path_to_string(
702 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
706 errors.push((path, err));
707 prev_root_id = import.root_id;
709 } else if is_indeterminate {
710 // Consider erroneous imports used to avoid duplicate diagnostics.
711 self.r.used_imports.insert(import.id);
712 let path = import_path_to_string(
713 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
717 let err = UnresolvedImportError {
723 if path.contains("::") {
724 errors.push((path, err))
729 if !errors.is_empty() {
730 self.throw_unresolved_import_error(errors, None);
734 fn throw_unresolved_import_error(
736 errors: Vec<(String, UnresolvedImportError)>,
737 span: Option<MultiSpan>,
739 /// Upper limit on the number of `span_label` messages.
740 const MAX_LABEL_COUNT: usize = 10;
742 let (span, msg) = if errors.is_empty() {
743 (span.unwrap(), "unresolved import".to_string())
745 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
747 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
749 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
754 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
756 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
757 for message in note {
762 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
763 if let Some(label) = err.label {
764 diag.span_label(err.span, label);
767 if let Some((suggestions, msg, applicability)) = err.suggestion {
768 diag.multipart_suggestion(&msg, suggestions, applicability);
775 /// Attempts to resolve the given import, returning true if its resolution is determined.
776 /// If successful, the resolved bindings are written into the module.
777 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
779 "(resolving import for module) resolving import `{}::...` in `{}`",
780 Segment::names_to_string(&import.module_path),
781 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
784 let module = if let Some(module) = import.imported_module.get() {
787 // For better failure detection, pretend that the import will
788 // not define any names while resolving its module path.
789 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
790 let path_res = self.r.resolve_path(
793 &import.parent_scope,
798 import.vis.set(orig_vis);
801 PathResult::Module(module) => module,
802 PathResult::Indeterminate => return false,
803 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
807 import.imported_module.set(Some(module));
808 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
816 } => (source, target, source_bindings, target_bindings, type_ns_only),
817 ImportKind::Glob { .. } => {
818 self.resolve_glob_import(import);
824 let mut indeterminate = false;
825 self.r.per_ns(|this, ns| {
826 if !type_ns_only || ns == TypeNS {
827 if let Err(Undetermined) = source_bindings[ns].get() {
828 // For better failure detection, pretend that the import will
829 // not define any names while resolving its module path.
830 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
831 let binding = this.resolve_ident_in_module(
835 &import.parent_scope,
839 import.vis.set(orig_vis);
840 source_bindings[ns].set(binding);
845 let parent = import.parent_scope.module;
846 match source_bindings[ns].get() {
847 Err(Undetermined) => indeterminate = true,
848 // Don't update the resolution, because it was never added.
849 Err(Determined) if target.name == kw::Underscore => {}
851 let key = this.new_key(target, ns);
852 this.update_resolution(parent, key, |_, resolution| {
853 resolution.single_imports.remove(&Interned::new_unchecked(import));
856 Ok(binding) if !binding.is_importable() => {
857 let msg = format!("`{}` is not directly importable", target);
858 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
859 .span_label(import.span, "cannot be imported directly")
861 // Do not import this illegal binding. Import a dummy binding and pretend
862 // everything is fine
863 this.import_dummy_binding(import);
866 let imported_binding = this.import(binding, import);
867 target_bindings[ns].set(Some(imported_binding));
868 this.define(parent, target, ns, imported_binding);
877 /// Performs final import resolution, consistency checks and error reporting.
879 /// Optionally returns an unresolved import error. This error is buffered and used to
880 /// consolidate multiple unresolved import errors into a single diagnostic.
881 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
882 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
883 let orig_unusable_binding = match &import.kind {
884 ImportKind::Single { target_bindings, .. } => {
885 Some(mem::replace(&mut self.r.unusable_binding, target_bindings[TypeNS].get()))
889 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
890 let path_res = self.r.resolve_path(
893 &import.parent_scope,
898 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
899 if let Some(orig_unusable_binding) = orig_unusable_binding {
900 self.r.unusable_binding = orig_unusable_binding;
902 import.vis.set(orig_vis);
903 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
904 // Consider erroneous imports used to avoid duplicate diagnostics.
905 self.r.used_imports.insert(import.id);
907 let module = match path_res {
908 PathResult::Module(module) => {
909 // Consistency checks, analogous to `finalize_macro_resolutions`.
910 if let Some(initial_module) = import.imported_module.get() {
911 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
912 span_bug!(import.span, "inconsistent resolution for an import");
914 } else if self.r.privacy_errors.is_empty() {
915 let msg = "cannot determine resolution for the import";
916 let msg_note = "import resolution is stuck, try simplifying other imports";
917 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
922 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
924 assert!(import.imported_module.get().is_none());
926 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
930 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
932 assert!(import.imported_module.get().is_none());
933 let err = match self.make_path_suggestion(
935 import.module_path.clone(),
936 &import.parent_scope,
938 Some((suggestion, note)) => UnresolvedImportError {
943 vec![(span, Segment::names_to_string(&suggestion))],
944 String::from("a similar path exists"),
945 Applicability::MaybeIncorrect,
948 None => UnresolvedImportError {
959 PathResult::NonModule(_) => {
961 assert!(import.imported_module.get().is_none());
963 // The error was already reported earlier.
966 PathResult::Indeterminate => unreachable!(),
969 let (ident, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
977 } => (source, target, source_bindings, target_bindings, type_ns_only),
978 ImportKind::Glob { is_prelude, ref max_vis } => {
979 if import.module_path.len() <= 1 {
980 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
981 // 2 segments, so the `resolve_path` above won't trigger it.
982 let mut full_path = import.module_path.clone();
983 full_path.push(Segment::from_ident(Ident::empty()));
984 self.r.lint_if_path_starts_with_module(
992 if let ModuleOrUniformRoot::Module(module) = module {
993 if ptr::eq(module, import.parent_scope.module) {
994 // Importing a module into itself is not allowed.
995 return Some(UnresolvedImportError {
997 label: Some(String::from("cannot glob-import a module into itself")),
1004 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
1005 !max_vis.get().is_at_least(import.vis.get(), &*self)
1007 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1008 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
1012 _ => unreachable!(),
1015 let mut all_ns_err = true;
1016 self.r.per_ns(|this, ns| {
1017 if !type_ns_only || ns == TypeNS {
1018 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
1019 let orig_unusable_binding =
1020 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1021 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1022 let binding = this.resolve_ident_in_module(
1026 &import.parent_scope,
1030 this.last_import_segment = orig_last_import_segment;
1031 this.unusable_binding = orig_unusable_binding;
1032 import.vis.set(orig_vis);
1036 // Consistency checks, analogous to `finalize_macro_resolutions`.
1037 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1039 if let Some(target_binding) = target_bindings[ns].get() {
1040 if target.name == kw::Underscore
1041 && initial_binding.is_extern_crate()
1042 && !initial_binding.is_import()
1047 import.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!(import.span, "inconsistent resolution for an import");
1058 } else if res != Res::Err
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";
1065 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
1069 // FIXME: This assert may fire if public glob is later shadowed by a private
1070 // single import (see test `issue-55884-2.rs`). In theory single imports should
1071 // always block globs, even if they are not yet resolved, so that this kind of
1072 // self-inconsistent resolution never happens.
1073 // Re-enable the assert when the issue is fixed.
1074 // assert!(result[ns].get().is_err());
1081 let mut all_ns_failed = true;
1082 self.r.per_ns(|this, ns| {
1083 if !type_ns_only || ns == TypeNS {
1084 let binding = this.resolve_ident_in_module(
1088 &import.parent_scope,
1092 if binding.is_ok() {
1093 all_ns_failed = false;
1098 return if all_ns_failed {
1099 let resolutions = match module {
1100 ModuleOrUniformRoot::Module(module) => {
1101 Some(self.r.resolutions(module).borrow())
1105 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1106 let names = resolutions
1107 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1110 } // Never suggest the same name
1111 match *resolution.borrow() {
1112 NameResolution { binding: Some(name_binding), .. } => {
1113 match name_binding.kind {
1114 NameBindingKind::Import { binding, .. } => {
1115 match binding.kind {
1116 // Never suggest the name that has binding error
1117 // i.e., the name that cannot be previously resolved
1118 NameBindingKind::Res(Res::Err, _) => None,
1125 NameResolution { ref single_imports, .. }
1126 if single_imports.is_empty() =>
1133 .collect::<Vec<Symbol>>();
1135 let lev_suggestion =
1136 find_best_match_for_name(&names, ident.name, 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(import, 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 {
1177 // `resolve_ident_in_module` reported a privacy error.
1178 self.r.import_dummy_binding(import);
1183 let mut reexport_error = None;
1184 let mut any_successful_reexport = false;
1185 let mut crate_private_reexport = false;
1186 self.r.per_ns(|this, ns| {
1187 if let Ok(binding) = source_bindings[ns].get() {
1188 let vis = import.vis.get();
1189 if !binding.vis.is_at_least(vis, &*this) {
1190 reexport_error = Some((ns, binding));
1191 if let ty::Visibility::Restricted(binding_def_id) = binding.vis {
1192 if binding_def_id.is_top_level_module() {
1193 crate_private_reexport = true;
1197 any_successful_reexport = true;
1202 // All namespaces must be re-exported with extra visibility for an error to occur.
1203 if !any_successful_reexport {
1204 let (ns, binding) = reexport_error.unwrap();
1205 if pub_use_of_private_extern_crate_hack(import, binding) {
1207 "extern crate `{}` is private, and cannot be \
1208 re-exported (error E0365), consider declaring with \
1212 self.r.lint_buffer.buffer_lint(
1213 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1219 let error_msg = if crate_private_reexport {
1221 "`{}` is only public within the crate, and cannot be re-exported outside",
1225 format!("`{}` is private, and cannot be re-exported", ident)
1229 let label_msg = if crate_private_reexport {
1230 format!("re-export of crate public `{}`", ident)
1232 format!("re-export of private `{}`", ident)
1235 struct_span_err!(self.r.session, import.span, E0365, "{}", error_msg)
1236 .span_label(import.span, label_msg)
1237 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1241 format!("consider marking `{}` as `pub` in the imported module", ident);
1242 struct_span_err!(self.r.session, import.span, E0364, "{}", error_msg)
1243 .span_note(import.span, ¬e_msg)
1249 if import.module_path.len() <= 1 {
1250 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1251 // 2 segments, so the `resolve_path` above won't trigger it.
1252 let mut full_path = import.module_path.clone();
1253 full_path.push(Segment::from_ident(ident));
1254 self.r.per_ns(|this, ns| {
1255 if let Ok(binding) = source_bindings[ns].get() {
1256 this.lint_if_path_starts_with_module(
1257 import.crate_lint(),
1266 // Record what this import resolves to for later uses in documentation,
1267 // this may resolve to either a value or a type, but for documentation
1268 // purposes it's good enough to just favor one over the other.
1269 self.r.per_ns(|this, ns| {
1270 if let Ok(binding) = source_bindings[ns].get() {
1271 this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res());
1275 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1277 debug!("(resolving single import) successfully resolved import");
1281 fn check_for_redundant_imports(
1284 import: &'b Import<'b>,
1285 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1286 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1289 // Skip if the import was produced by a macro.
1290 if import.parent_scope.expansion != LocalExpnId::ROOT {
1294 // Skip if we are inside a named module (in contrast to an anonymous
1295 // module defined by a block).
1296 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1300 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1302 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1304 self.r.per_ns(|this, ns| {
1305 if let Ok(binding) = source_bindings[ns].get() {
1306 if binding.res() == Res::Err {
1310 let orig_unusable_binding =
1311 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1313 match this.early_resolve_ident_in_lexical_scope(
1315 ScopeSet::All(ns, false),
1316 &import.parent_scope,
1321 Ok(other_binding) => {
1322 is_redundant[ns] = Some(
1323 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1325 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1327 Err(_) => is_redundant[ns] = Some(false),
1330 this.unusable_binding = orig_unusable_binding;
1334 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1336 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1337 redundant_spans.sort();
1338 redundant_spans.dedup();
1339 self.r.lint_buffer.buffer_lint_with_diagnostic(
1343 &format!("the item `{}` is imported redundantly", ident),
1344 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1349 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1350 let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
1351 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1355 if module.is_trait() {
1356 self.r.session.span_err(import.span, "items in traits are not importable");
1358 } else if ptr::eq(module, import.parent_scope.module) {
1360 } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind {
1361 self.r.prelude = Some(module);
1365 // Add to module's glob_importers
1366 module.glob_importers.borrow_mut().push(import);
1368 // Ensure that `resolutions` isn't borrowed during `try_define`,
1369 // since it might get updated via a glob cycle.
1372 .resolutions(module)
1375 .filter_map(|(key, resolution)| {
1376 resolution.borrow().binding().map(|binding| (*key, binding))
1378 .collect::<Vec<_>>();
1379 for (mut key, binding) in bindings {
1380 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1381 Some(Some(def)) => self.r.expn_def_scope(def),
1382 Some(None) => import.parent_scope.module,
1385 if self.r.is_accessible_from(binding.vis, scope) {
1386 let imported_binding = self.r.import(binding, import);
1387 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1391 // Record the destination of this import
1392 self.r.record_partial_res(import.id, PartialRes::new(module.res().unwrap()));
1395 // Miscellaneous post-processing, including recording re-exports,
1396 // reporting conflicts, and reporting unresolved imports.
1397 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1398 // Since import resolution is finished, globs will not define any more names.
1399 *module.globs.borrow_mut() = Vec::new();
1401 let mut reexports = Vec::new();
1403 module.for_each_child(self.r, |_, ident, _, binding| {
1404 // FIXME: Consider changing the binding inserted by `#[macro_export] macro_rules`
1405 // into the crate root to actual `NameBindingKind::Import`.
1406 if binding.is_import()
1407 || matches!(binding.kind, NameBindingKind::Res(_, _is_macro_export @ true))
1409 let res = binding.res().expect_non_local();
1410 // Ambiguous imports are treated as errors at this point and are
1411 // not exposed to other crates (see #36837 for more details).
1412 if res != def::Res::Err && !binding.is_ambiguity() {
1413 reexports.push(ModChild {
1424 if !reexports.is_empty() {
1425 if let Some(def_id) = module.opt_def_id() {
1426 // Call to `expect_local` should be fine because current
1427 // code is only called for local modules.
1428 self.r.reexport_map.insert(def_id.expect_local(), reexports);
1434 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1435 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1436 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1437 if let Some(pos) = pos {
1438 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1439 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1441 let names = if global { &names[1..] } else { names };
1442 if names.is_empty() {
1443 import_kind_to_string(import_kind)
1447 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1448 import_kind_to_string(import_kind),
1454 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1456 ImportKind::Single { source, .. } => source.to_string(),
1457 ImportKind::Glob { .. } => "*".to_string(),
1458 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1459 ImportKind::MacroUse => "#[macro_use]".to_string(),