1 //! A bunch of methods and structures more or less related to resolving imports.
3 use crate::diagnostics::{import_candidates, Suggestion};
4 use crate::Determinacy::{self, *};
5 use crate::Namespace::*;
6 use crate::{module_to_string, names_to_string, ImportSuggestion};
7 use crate::{AmbiguityKind, BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
8 use crate::{Finalize, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet};
9 use crate::{NameBinding, NameBindingKind, PathResult};
11 use rustc_ast::NodeId;
12 use rustc_data_structures::fx::FxHashSet;
13 use rustc_data_structures::intern::Interned;
14 use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
15 use rustc_hir::def::{self, DefKind, PartialRes};
16 use rustc_middle::metadata::ModChild;
17 use rustc_middle::span_bug;
19 use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
20 use rustc_session::lint::BuiltinLintDiagnostics;
21 use rustc_span::hygiene::LocalExpnId;
22 use rustc_span::lev_distance::find_best_match_for_name;
23 use rustc_span::symbol::{kw, Ident, Symbol};
29 type Res = def::Res<NodeId>;
31 /// Contains data for specific kinds of imports.
33 pub enum ImportKind<'a> {
35 /// `source` in `use prefix::source as target`.
37 /// `target` in `use prefix::source as target`.
39 /// Bindings to which `source` refers to.
40 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
41 /// Bindings introduced by `target`.
42 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
43 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
45 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
47 /// The ID of the `UseTree` that imported this `Import`.
49 /// In the case where the `Import` was expanded from a "nested" use tree,
50 /// this id is the ID of the leaf tree. For example:
52 /// ```ignore (pacify the merciless tidy)
53 /// use foo::bar::{a, b}
56 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
57 /// for `a` in this field.
59 /// Additional `NodeId`s allocated to a `ast::UseTree` for automatically generated `use` statement
60 /// (eg. implicit struct constructors)
61 additional_ids: (NodeId, NodeId),
65 // The visibility of the greatest re-export.
66 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
67 max_vis: Cell<Option<ty::Visibility>>,
71 source: Option<Symbol>,
79 /// Manually implement `Debug` for `ImportKind` because the `source/target_bindings`
80 /// contain `Cell`s which can introduce infinite loops while printing.
81 impl<'a> std::fmt::Debug for ImportKind<'a> {
82 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
92 // Ignore the following to avoid an infinite loop while printing.
96 .debug_struct("Single")
97 .field("source", source)
98 .field("target", target)
99 .field("type_ns_only", type_ns_only)
100 .field("nested", nested)
102 .field("additional_ids", additional_ids)
103 .finish_non_exhaustive(),
104 Glob { ref is_prelude, ref max_vis, ref id } => f
105 .debug_struct("Glob")
106 .field("is_prelude", is_prelude)
107 .field("max_vis", max_vis)
110 ExternCrate { ref source, ref target, ref id } => f
111 .debug_struct("ExternCrate")
112 .field("source", source)
113 .field("target", target)
116 MacroUse => f.debug_struct("MacroUse").finish(),
117 MacroExport => f.debug_struct("MacroExport").finish(),
123 #[derive(Debug, Clone)]
124 pub(crate) struct Import<'a> {
125 pub kind: ImportKind<'a>,
127 /// Node ID of the "root" use item -- this is always the same as `ImportKind`'s `id`
128 /// (if it exists) except in the case of "nested" use trees, in which case
129 /// it will be the ID of the root use tree. e.g., in the example
130 /// ```ignore (incomplete code)
131 /// use foo::bar::{a, b}
133 /// this would be the ID of the `use foo::bar` `UseTree` node.
134 /// In case of imports without their own node ID it's the closest node that can be used,
135 /// for example, for reporting lints.
138 /// Span of the entire use statement.
141 /// Span of the entire use statement with attributes.
142 pub use_span_with_attributes: Span,
144 /// Did the use statement have any attributes?
145 pub has_attributes: bool,
147 /// Span of this use tree.
150 /// Span of the *root* use tree (see `root_id`).
153 pub parent_scope: ParentScope<'a>,
154 pub module_path: Vec<Segment>,
155 /// The resolution of `module_path`.
156 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
157 pub vis: Cell<Option<ty::Visibility>>,
158 pub used: Cell<bool>,
161 impl<'a> Import<'a> {
162 pub fn is_glob(&self) -> bool {
163 matches!(self.kind, ImportKind::Glob { .. })
166 pub fn is_nested(&self) -> bool {
168 ImportKind::Single { nested, .. } => nested,
173 pub(crate) fn expect_vis(&self) -> ty::Visibility {
174 self.vis.get().expect("encountered cleared import visibility")
177 pub(crate) fn id(&self) -> Option<NodeId> {
179 ImportKind::Single { id, .. }
180 | ImportKind::Glob { id, .. }
181 | ImportKind::ExternCrate { id, .. } => Some(id),
182 ImportKind::MacroUse | ImportKind::MacroExport => None,
187 /// Records information about the resolution of a name in a namespace of a module.
188 #[derive(Clone, Default, Debug)]
189 pub(crate) struct NameResolution<'a> {
190 /// Single imports that may define the name in the namespace.
191 /// Imports are arena-allocated, so it's ok to use pointers as keys.
192 pub single_imports: FxHashSet<Interned<'a, Import<'a>>>,
193 /// The least shadowable known binding for this name, or None if there are no known bindings.
194 pub binding: Option<&'a NameBinding<'a>>,
195 pub shadowed_glob: Option<&'a NameBinding<'a>>,
198 impl<'a> NameResolution<'a> {
199 // Returns the binding for the name if it is known or None if it not known.
200 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
201 self.binding.and_then(|binding| {
202 if !binding.is_glob_import() || self.single_imports.is_empty() {
210 pub(crate) fn add_single_import(&mut self, import: &'a Import<'a>) {
211 self.single_imports.insert(Interned::new_unchecked(import));
215 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
216 // are permitted for backward-compatibility under a deprecation lint.
217 fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
218 match (&import.kind, &binding.kind) {
220 ImportKind::Single { .. },
221 NameBindingKind::Import {
222 import: Import { kind: ImportKind::ExternCrate { .. }, .. },
225 ) => import.expect_vis().is_public(),
230 impl<'a> Resolver<'a> {
231 // Given a binding and an import that resolves to it,
232 // return the corresponding binding defined by the import.
233 pub(crate) fn import(
235 binding: &'a NameBinding<'a>,
236 import: &'a Import<'a>,
237 ) -> &'a NameBinding<'a> {
238 let import_vis = import.expect_vis().to_def_id();
239 let vis = if binding.vis.is_at_least(import_vis, self)
240 || pub_use_of_private_extern_crate_hack(import, binding)
247 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
249 || max_vis.get().map_or(true, |max_vis| vis.is_at_least(max_vis, self))
251 max_vis.set(Some(vis.expect_local()))
255 self.arenas.alloc_name_binding(NameBinding {
256 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
260 expansion: import.parent_scope.expansion,
264 // Define the name or return the existing binding if there is a collision.
265 pub(crate) fn try_define(
269 binding: &'a NameBinding<'a>,
270 ) -> Result<(), &'a NameBinding<'a>> {
271 let res = binding.res();
272 self.check_reserved_macro_name(key.ident, res);
273 self.set_binding_parent_module(binding, module);
274 self.update_resolution(module, key, |this, resolution| {
275 if let Some(old_binding) = resolution.binding {
276 if res == Res::Err && old_binding.res() != Res::Err {
277 // Do not override real bindings with `Res::Err`s from error recovery.
280 match (old_binding.is_glob_import(), binding.is_glob_import()) {
282 if res != old_binding.res() {
283 resolution.binding = Some(this.ambiguity(
284 AmbiguityKind::GlobVsGlob,
288 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
289 // We are glob-importing the same item but with greater visibility.
290 resolution.binding = Some(binding);
293 (old_glob @ true, false) | (old_glob @ false, true) => {
294 let (glob_binding, nonglob_binding) =
295 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
296 if glob_binding.res() != nonglob_binding.res()
298 && nonglob_binding.expansion != LocalExpnId::ROOT
300 resolution.binding = Some(this.ambiguity(
301 AmbiguityKind::GlobVsExpanded,
306 resolution.binding = Some(nonglob_binding);
308 resolution.shadowed_glob = Some(glob_binding);
311 return Err(old_binding);
315 resolution.binding = Some(binding);
325 primary_binding: &'a NameBinding<'a>,
326 secondary_binding: &'a NameBinding<'a>,
327 ) -> &'a NameBinding<'a> {
328 self.arenas.alloc_name_binding(NameBinding {
329 ambiguity: Some((secondary_binding, kind)),
330 ..primary_binding.clone()
334 // Use `f` to mutate the resolution of the name in the module.
335 // If the resolution becomes a success, define it in the module's glob importers.
336 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
338 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
340 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
341 // during which the resolution might end up getting re-defined via a glob cycle.
343 let resolution = &mut *self.resolution(module, key).borrow_mut();
344 let old_binding = resolution.binding();
346 let t = f(self, resolution);
348 match resolution.binding() {
349 _ if old_binding.is_some() => return t,
351 Some(binding) => match old_binding {
352 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
358 // Define `binding` in `module`s glob importers.
359 for import in module.glob_importers.borrow_mut().iter() {
360 let mut ident = key.ident;
361 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
362 Some(Some(def)) => self.expn_def_scope(def),
363 Some(None) => import.parent_scope.module,
366 if self.is_accessible_from(binding.vis, scope) {
367 let imported_binding = self.import(binding, import);
368 let key = BindingKey { ident, ..key };
369 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
376 // Define a dummy resolution containing a `Res::Err` as a placeholder for a failed resolution,
377 // also mark such failed imports as used to avoid duplicate diagnostics.
378 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
379 if let ImportKind::Single { target, ref target_bindings, .. } = import.kind {
380 if target_bindings.iter().any(|binding| binding.get().is_some()) {
381 return; // Has resolution, do not create the dummy binding
383 let dummy_binding = self.dummy_binding;
384 let dummy_binding = self.import(dummy_binding, import);
385 self.per_ns(|this, ns| {
386 let key = this.new_key(target, ns);
387 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
389 self.record_use(target, dummy_binding, false);
390 } else if import.imported_module.get().is_none() {
391 import.used.set(true);
392 if let Some(id) = import.id() {
393 self.used_imports.insert(id);
399 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
400 /// import errors within the same use tree into a single diagnostic.
401 #[derive(Debug, Clone)]
402 struct UnresolvedImportError {
404 label: Option<String>,
405 note: Option<String>,
406 suggestion: Option<Suggestion>,
407 candidate: Option<Vec<ImportSuggestion>>,
410 pub struct ImportResolver<'a, 'b> {
411 pub r: &'a mut Resolver<'b>,
414 impl<'a, 'b> ImportResolver<'a, 'b> {
417 // This is a fixed-point algorithm. We resolve imports until our efforts
418 // are stymied by an unresolved import; then we bail out of the current
419 // module and continue. We terminate successfully once no more imports
420 // remain or unsuccessfully when no forward progress in resolving imports
423 /// Resolves all imports for the crate. This method performs the fixed-
425 pub fn resolve_imports(&mut self) {
426 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
427 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
428 prev_num_indeterminates = self.r.indeterminate_imports.len();
429 for import in mem::take(&mut self.r.indeterminate_imports) {
430 match self.resolve_import(&import) {
431 true => self.r.determined_imports.push(import),
432 false => self.r.indeterminate_imports.push(import),
438 pub fn finalize_imports(&mut self) {
439 for module in self.r.arenas.local_modules().iter() {
440 self.finalize_resolutions_in(module);
443 let mut seen_spans = FxHashSet::default();
444 let mut errors = vec![];
445 let mut prev_root_id: NodeId = NodeId::from_u32(0);
446 let determined_imports = mem::take(&mut self.r.determined_imports);
447 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
449 for (is_indeterminate, import) in determined_imports
452 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
454 let unresolved_import_error = self.finalize_import(import);
456 // If this import is unresolved then create a dummy import
457 // resolution for it so that later resolve stages won't complain.
458 self.r.import_dummy_binding(import);
460 if let Some(err) = unresolved_import_error {
461 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
462 if source.name == kw::SelfLower {
463 // Silence `unresolved import` error if E0429 is already emitted
464 if let Err(Determined) = source_bindings.value_ns.get() {
470 if prev_root_id.as_u32() != 0
471 && prev_root_id.as_u32() != import.root_id.as_u32()
472 && !errors.is_empty()
474 // In the case of a new import line, throw a diagnostic message
475 // for the previous line.
476 self.throw_unresolved_import_error(errors);
479 if seen_spans.insert(err.span) {
480 let path = import_path_to_string(
481 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
485 errors.push((path, err));
486 prev_root_id = import.root_id;
488 } else if is_indeterminate {
489 let path = import_path_to_string(
490 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
494 let err = UnresolvedImportError {
501 if path.contains("::") {
502 errors.push((path, err))
507 if !errors.is_empty() {
508 self.throw_unresolved_import_error(errors);
512 fn throw_unresolved_import_error(&self, errors: Vec<(String, UnresolvedImportError)>) {
513 if errors.is_empty() {
517 /// Upper limit on the number of `span_label` messages.
518 const MAX_LABEL_COUNT: usize = 10;
520 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
521 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
522 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
524 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
526 if let Some((_, UnresolvedImportError { note: Some(note), .. })) = errors.iter().last() {
530 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
531 if let Some(label) = err.label {
532 diag.span_label(err.span, label);
535 if let Some((suggestions, msg, applicability)) = err.suggestion {
536 if suggestions.is_empty() {
540 diag.multipart_suggestion(&msg, suggestions, applicability);
543 if let Some(candidate) = &err.candidate {
557 /// Attempts to resolve the given import, returning true if its resolution is determined.
558 /// If successful, the resolved bindings are written into the module.
559 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
561 "(resolving import for module) resolving import `{}::...` in `{}`",
562 Segment::names_to_string(&import.module_path),
563 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
566 let module = if let Some(module) = import.imported_module.get() {
569 // For better failure detection, pretend that the import will
570 // not define any names while resolving its module path.
571 let orig_vis = import.vis.take();
573 self.r.maybe_resolve_path(&import.module_path, None, &import.parent_scope);
574 import.vis.set(orig_vis);
577 PathResult::Module(module) => module,
578 PathResult::Indeterminate => return false,
579 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
583 import.imported_module.set(Some(module));
584 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
592 } => (source, target, source_bindings, target_bindings, type_ns_only),
593 ImportKind::Glob { .. } => {
594 self.resolve_glob_import(import);
600 let mut indeterminate = false;
601 self.r.per_ns(|this, ns| {
602 if !type_ns_only || ns == TypeNS {
603 if let Err(Undetermined) = source_bindings[ns].get() {
604 // For better failure detection, pretend that the import will
605 // not define any names while resolving its module path.
606 let orig_vis = import.vis.take();
607 let binding = this.resolve_ident_in_module(
611 &import.parent_scope,
615 import.vis.set(orig_vis);
616 source_bindings[ns].set(binding);
621 let parent = import.parent_scope.module;
622 match source_bindings[ns].get() {
623 Err(Undetermined) => indeterminate = true,
624 // Don't update the resolution, because it was never added.
625 Err(Determined) if target.name == kw::Underscore => {}
626 Ok(binding) if binding.is_importable() => {
627 let imported_binding = this.import(binding, import);
628 target_bindings[ns].set(Some(imported_binding));
629 this.define(parent, target, ns, imported_binding);
631 source_binding @ (Ok(..) | Err(Determined)) => {
632 if source_binding.is_ok() {
633 let msg = format!("`{}` is not directly importable", target);
634 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
635 .span_label(import.span, "cannot be imported directly")
638 let key = this.new_key(target, ns);
639 this.update_resolution(parent, key, |_, resolution| {
640 resolution.single_imports.remove(&Interned::new_unchecked(import));
650 /// Performs final import resolution, consistency checks and error reporting.
652 /// Optionally returns an unresolved import error. This error is buffered and used to
653 /// consolidate multiple unresolved import errors into a single diagnostic.
654 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
655 let orig_vis = import.vis.take();
656 let ignore_binding = match &import.kind {
657 ImportKind::Single { target_bindings, .. } => target_bindings[TypeNS].get(),
660 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
661 let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span);
662 let path_res = self.r.resolve_path(
665 &import.parent_scope,
670 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
671 import.vis.set(orig_vis);
672 let module = match path_res {
673 PathResult::Module(module) => {
674 // Consistency checks, analogous to `finalize_macro_resolutions`.
675 if let Some(initial_module) = import.imported_module.get() {
676 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
677 span_bug!(import.span, "inconsistent resolution for an import");
679 } else if self.r.privacy_errors.is_empty() {
680 let msg = "cannot determine resolution for the import";
681 let msg_note = "import resolution is stuck, try simplifying other imports";
682 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
687 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
689 assert!(import.imported_module.get().is_none());
691 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
695 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
697 assert!(import.imported_module.get().is_none());
698 let err = match self.make_path_suggestion(
700 import.module_path.clone(),
701 &import.parent_scope,
703 Some((suggestion, note)) => UnresolvedImportError {
708 vec![(span, Segment::names_to_string(&suggestion))],
709 String::from("a similar path exists"),
710 Applicability::MaybeIncorrect,
714 None => UnresolvedImportError {
726 PathResult::NonModule(_) => {
728 assert!(import.imported_module.get().is_none());
730 // The error was already reported earlier.
733 PathResult::Indeterminate => unreachable!(),
736 let (ident, target, source_bindings, target_bindings, type_ns_only, import_id) =
746 } => (source, target, source_bindings, target_bindings, type_ns_only, id),
747 ImportKind::Glob { is_prelude, ref max_vis, id } => {
748 if import.module_path.len() <= 1 {
749 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
750 // 2 segments, so the `resolve_path` above won't trigger it.
751 let mut full_path = import.module_path.clone();
752 full_path.push(Segment::from_ident(Ident::empty()));
753 self.r.lint_if_path_starts_with_module(Some(finalize), &full_path, None);
756 if let ModuleOrUniformRoot::Module(module) = module {
757 if ptr::eq(module, import.parent_scope.module) {
758 // Importing a module into itself is not allowed.
759 return Some(UnresolvedImportError {
761 label: Some(String::from(
762 "cannot glob-import a module into itself",
771 && let Some(max_vis) = max_vis.get()
772 && !max_vis.is_at_least(import.expect_vis(), &*self.r)
774 let msg = "glob import doesn't reexport anything because no candidate is public enough";
775 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, id, import.span, msg);
782 let mut all_ns_err = true;
783 self.r.per_ns(|this, ns| {
784 if !type_ns_only || ns == TypeNS {
785 let orig_vis = import.vis.take();
786 let binding = this.resolve_ident_in_module(
790 &import.parent_scope,
791 Some(Finalize { report_private: false, ..finalize }),
792 target_bindings[ns].get(),
794 import.vis.set(orig_vis);
798 // Consistency checks, analogous to `finalize_macro_resolutions`.
799 let initial_res = source_bindings[ns].get().map(|initial_binding| {
801 if let Some(target_binding) = target_bindings[ns].get() {
802 if target.name == kw::Underscore
803 && initial_binding.is_extern_crate()
804 && !initial_binding.is_import()
809 import.module_path.is_empty(),
813 initial_binding.res()
815 let res = binding.res();
816 if let Ok(initial_res) = initial_res {
817 if res != initial_res && this.ambiguity_errors.is_empty() {
818 span_bug!(import.span, "inconsistent resolution for an import");
820 } else if res != Res::Err
821 && this.ambiguity_errors.is_empty()
822 && this.privacy_errors.is_empty()
824 let msg = "cannot determine resolution for the import";
826 "import resolution is stuck, try simplifying other imports";
827 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
831 // FIXME: This assert may fire if public glob is later shadowed by a private
832 // single import (see test `issue-55884-2.rs`). In theory single imports should
833 // always block globs, even if they are not yet resolved, so that this kind of
834 // self-inconsistent resolution never happens.
835 // Re-enable the assert when the issue is fixed.
836 // assert!(result[ns].get().is_err());
843 let mut all_ns_failed = true;
844 self.r.per_ns(|this, ns| {
845 if !type_ns_only || ns == TypeNS {
846 let binding = this.resolve_ident_in_module(
850 &import.parent_scope,
855 all_ns_failed = false;
860 return if all_ns_failed {
861 let resolutions = match module {
862 ModuleOrUniformRoot::Module(module) => {
863 Some(self.r.resolutions(module).borrow())
867 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
868 let names = resolutions
869 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
872 } // Never suggest the same name
873 match *resolution.borrow() {
874 NameResolution { binding: Some(name_binding), .. } => {
875 match name_binding.kind {
876 NameBindingKind::Import { binding, .. } => {
878 // Never suggest the name that has binding error
879 // i.e., the name that cannot be previously resolved
880 NameBindingKind::Res(Res::Err) => None,
887 NameResolution { ref single_imports, .. }
888 if single_imports.is_empty() =>
895 .collect::<Vec<Symbol>>();
898 find_best_match_for_name(&names, ident.name, None).map(|suggestion| {
900 vec![(ident.span, suggestion.to_string())],
901 String::from("a similar name exists in the module"),
902 Applicability::MaybeIncorrect,
906 let (suggestion, note) =
907 match self.check_for_module_export_macro(import, module, ident) {
908 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
909 _ => (lev_suggestion, None),
912 let label = match module {
913 ModuleOrUniformRoot::Module(module) => {
914 let module_str = module_to_string(module);
915 if let Some(module_str) = module_str {
916 format!("no `{}` in `{}`", ident, module_str)
918 format!("no `{}` in the root", ident)
922 if !ident.is_path_segment_keyword() {
923 format!("no external crate `{}`", ident)
925 // HACK(eddyb) this shows up for `self` & `super`, which
926 // should work instead - for now keep the same error message.
927 format!("no `{}` in the root", ident)
932 let parent_suggestion =
933 self.r.lookup_import_candidates(ident, TypeNS, &import.parent_scope, |_| true);
935 Some(UnresolvedImportError {
940 candidate: if !parent_suggestion.is_empty() {
941 Some(parent_suggestion)
947 // `resolve_ident_in_module` reported a privacy error.
952 let mut reexport_error = None;
953 let mut any_successful_reexport = false;
954 let mut crate_private_reexport = false;
955 self.r.per_ns(|this, ns| {
956 if let Ok(binding) = source_bindings[ns].get() {
957 if !binding.vis.is_at_least(import.expect_vis(), &*this) {
958 reexport_error = Some((ns, binding));
959 if let ty::Visibility::Restricted(binding_def_id) = binding.vis {
960 if binding_def_id.is_top_level_module() {
961 crate_private_reexport = true;
965 any_successful_reexport = true;
970 // All namespaces must be re-exported with extra visibility for an error to occur.
971 if !any_successful_reexport {
972 let (ns, binding) = reexport_error.unwrap();
973 if pub_use_of_private_extern_crate_hack(import, binding) {
975 "extern crate `{}` is private, and cannot be \
976 re-exported (error E0365), consider declaring with \
980 self.r.lint_buffer.buffer_lint(
981 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
987 let error_msg = if crate_private_reexport {
989 "`{}` is only public within the crate, and cannot be re-exported outside",
993 format!("`{}` is private, and cannot be re-exported", ident)
997 let label_msg = if crate_private_reexport {
998 format!("re-export of crate public `{}`", ident)
1000 format!("re-export of private `{}`", ident)
1003 struct_span_err!(self.r.session, import.span, E0365, "{}", error_msg)
1004 .span_label(import.span, label_msg)
1005 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1009 struct_span_err!(self.r.session, import.span, E0364, "{error_msg}");
1010 match binding.kind {
1011 NameBindingKind::Res(Res::Def(DefKind::Macro(_), def_id))
1012 // exclude decl_macro
1013 if self.r.get_macro_by_def_id(def_id).macro_rules =>
1017 "consider adding a `#[macro_export]` to the macro in the imported module",
1024 "consider marking `{ident}` as `pub` in the imported module"
1034 if import.module_path.len() <= 1 {
1035 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1036 // 2 segments, so the `resolve_path` above won't trigger it.
1037 let mut full_path = import.module_path.clone();
1038 full_path.push(Segment::from_ident(ident));
1039 self.r.per_ns(|this, ns| {
1040 if let Ok(binding) = source_bindings[ns].get() {
1041 this.lint_if_path_starts_with_module(Some(finalize), &full_path, Some(binding));
1046 // Record what this import resolves to for later uses in documentation,
1047 // this may resolve to either a value or a type, but for documentation
1048 // purposes it's good enough to just favor one over the other.
1049 self.r.per_ns(|this, ns| {
1050 if let Ok(binding) = source_bindings[ns].get() {
1051 this.import_res_map.entry(import_id).or_default()[ns] = Some(binding.res());
1055 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1057 debug!("(resolving single import) successfully resolved import");
1061 fn check_for_redundant_imports(
1064 import: &'b Import<'b>,
1065 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1066 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1069 // This function is only called for single imports.
1070 let ImportKind::Single { id, .. } = import.kind else { unreachable!() };
1072 // Skip if the import was produced by a macro.
1073 if import.parent_scope.expansion != LocalExpnId::ROOT {
1077 // Skip if we are inside a named module (in contrast to an anonymous
1078 // module defined by a block).
1079 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1083 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1085 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1087 self.r.per_ns(|this, ns| {
1088 if let Ok(binding) = source_bindings[ns].get() {
1089 if binding.res() == Res::Err {
1093 match this.early_resolve_ident_in_lexical_scope(
1095 ScopeSet::All(ns, false),
1096 &import.parent_scope,
1099 target_bindings[ns].get(),
1101 Ok(other_binding) => {
1102 is_redundant[ns] = Some(
1103 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1105 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1107 Err(_) => is_redundant[ns] = Some(false),
1112 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1114 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1115 redundant_spans.sort();
1116 redundant_spans.dedup();
1117 self.r.lint_buffer.buffer_lint_with_diagnostic(
1121 &format!("the item `{}` is imported redundantly", ident),
1122 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1127 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1128 // This function is only called for glob imports.
1129 let ImportKind::Glob { id, is_prelude, .. } = import.kind else { unreachable!() };
1131 let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
1132 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1136 if module.is_trait() {
1137 self.r.session.span_err(import.span, "items in traits are not importable");
1139 } else if ptr::eq(module, import.parent_scope.module) {
1141 } else if is_prelude {
1142 self.r.prelude = Some(module);
1146 // Add to module's glob_importers
1147 module.glob_importers.borrow_mut().push(import);
1149 // Ensure that `resolutions` isn't borrowed during `try_define`,
1150 // since it might get updated via a glob cycle.
1153 .resolutions(module)
1156 .filter_map(|(key, resolution)| {
1157 resolution.borrow().binding().map(|binding| (*key, binding))
1159 .collect::<Vec<_>>();
1160 for (mut key, binding) in bindings {
1161 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1162 Some(Some(def)) => self.r.expn_def_scope(def),
1163 Some(None) => import.parent_scope.module,
1166 if self.r.is_accessible_from(binding.vis, scope) {
1167 let imported_binding = self.r.import(binding, import);
1168 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1172 // Record the destination of this import
1173 self.r.record_partial_res(id, PartialRes::new(module.res().unwrap()));
1176 // Miscellaneous post-processing, including recording re-exports,
1177 // reporting conflicts, and reporting unresolved imports.
1178 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1179 // Since import resolution is finished, globs will not define any more names.
1180 *module.globs.borrow_mut() = Vec::new();
1182 if let Some(def_id) = module.opt_def_id() {
1183 let mut reexports = Vec::new();
1185 module.for_each_child(self.r, |this, ident, _, binding| {
1186 if let Some(res) = this.is_reexport(binding) {
1187 reexports.push(ModChild {
1197 if !reexports.is_empty() {
1198 // Call to `expect_local` should be fine because current
1199 // code is only called for local modules.
1200 self.r.reexport_map.insert(def_id.expect_local(), reexports);
1206 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1207 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1208 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1209 if let Some(pos) = pos {
1210 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1211 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1213 let names = if global { &names[1..] } else { names };
1214 if names.is_empty() {
1215 import_kind_to_string(import_kind)
1219 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1220 import_kind_to_string(import_kind),
1226 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1228 ImportKind::Single { source, .. } => source.to_string(),
1229 ImportKind::Glob { .. } => "*".to_string(),
1230 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1231 ImportKind::MacroUse => "#[macro_use]".to_string(),
1232 ImportKind::MacroExport => "#[macro_export]".to_string(),