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.
62 // The visibility of the greatest re-export.
63 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
64 max_vis: Cell<Option<ty::Visibility>>,
68 source: Option<Symbol>,
76 /// Manually implement `Debug` for `ImportKind` because the `source/target_bindings`
77 /// contain `Cell`s which can introduce infinite loops while printing.
78 impl<'a> std::fmt::Debug for ImportKind<'a> {
79 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
88 // Ignore the following to avoid an infinite loop while printing.
92 .debug_struct("Single")
93 .field("source", source)
94 .field("target", target)
95 .field("type_ns_only", type_ns_only)
96 .field("nested", nested)
98 .finish_non_exhaustive(),
99 Glob { ref is_prelude, ref max_vis, ref id } => f
100 .debug_struct("Glob")
101 .field("is_prelude", is_prelude)
102 .field("max_vis", max_vis)
105 ExternCrate { ref source, ref target, ref id } => f
106 .debug_struct("ExternCrate")
107 .field("source", source)
108 .field("target", target)
111 MacroUse => f.debug_struct("MacroUse").finish(),
112 MacroExport => f.debug_struct("MacroExport").finish(),
118 #[derive(Debug, Clone)]
119 pub(crate) struct Import<'a> {
120 pub kind: ImportKind<'a>,
122 /// Node ID of the "root" use item -- this is always the same as `ImportKind`'s `id`
123 /// (if it exists) except in the case of "nested" use trees, in which case
124 /// it will be the ID of the root use tree. e.g., in the example
125 /// ```ignore (incomplete code)
126 /// use foo::bar::{a, b}
128 /// this would be the ID of the `use foo::bar` `UseTree` node.
129 /// In case of imports without their own node ID it's the closest node that can be used,
130 /// for example, for reporting lints.
133 /// Span of the entire use statement.
136 /// Span of the entire use statement with attributes.
137 pub use_span_with_attributes: Span,
139 /// Did the use statement have any attributes?
140 pub has_attributes: bool,
142 /// Span of this use tree.
145 /// Span of the *root* use tree (see `root_id`).
148 pub parent_scope: ParentScope<'a>,
149 pub module_path: Vec<Segment>,
150 /// The resolution of `module_path`.
151 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
152 pub vis: Cell<Option<ty::Visibility>>,
153 pub used: Cell<bool>,
156 impl<'a> Import<'a> {
157 pub fn is_glob(&self) -> bool {
158 matches!(self.kind, ImportKind::Glob { .. })
161 pub fn is_nested(&self) -> bool {
163 ImportKind::Single { nested, .. } => nested,
168 pub(crate) fn expect_vis(&self) -> ty::Visibility {
169 self.vis.get().expect("encountered cleared import visibility")
172 pub(crate) fn id(&self) -> Option<NodeId> {
174 ImportKind::Single { id, .. }
175 | ImportKind::Glob { id, .. }
176 | ImportKind::ExternCrate { id, .. } => Some(id),
177 ImportKind::MacroUse | ImportKind::MacroExport => None,
182 /// Records information about the resolution of a name in a namespace of a module.
183 #[derive(Clone, Default, Debug)]
184 pub(crate) struct NameResolution<'a> {
185 /// Single imports that may define the name in the namespace.
186 /// Imports are arena-allocated, so it's ok to use pointers as keys.
187 pub single_imports: FxHashSet<Interned<'a, Import<'a>>>,
188 /// The least shadowable known binding for this name, or None if there are no known bindings.
189 pub binding: Option<&'a NameBinding<'a>>,
190 pub shadowed_glob: Option<&'a NameBinding<'a>>,
193 impl<'a> NameResolution<'a> {
194 /// Returns the binding for the name if it is known or None if it not known.
195 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
196 self.binding.and_then(|binding| {
197 if !binding.is_glob_import() || self.single_imports.is_empty() {
205 pub(crate) fn add_single_import(&mut self, import: &'a Import<'a>) {
206 self.single_imports.insert(Interned::new_unchecked(import));
210 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
211 // are permitted for backward-compatibility under a deprecation lint.
212 fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
213 match (&import.kind, &binding.kind) {
215 ImportKind::Single { .. },
216 NameBindingKind::Import {
217 import: Import { kind: ImportKind::ExternCrate { .. }, .. },
220 ) => import.expect_vis().is_public(),
225 impl<'a> Resolver<'a> {
226 /// Given a binding and an import that resolves to it,
227 /// return the corresponding binding defined by the import.
228 pub(crate) fn import(
230 binding: &'a NameBinding<'a>,
231 import: &'a Import<'a>,
232 ) -> &'a NameBinding<'a> {
233 let import_vis = import.expect_vis().to_def_id();
234 let vis = if binding.vis.is_at_least(import_vis, self)
235 || pub_use_of_private_extern_crate_hack(import, binding)
242 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
244 || max_vis.get().map_or(true, |max_vis| vis.is_at_least(max_vis, self))
246 max_vis.set(Some(vis.expect_local()))
250 self.arenas.alloc_name_binding(NameBinding {
251 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
255 expansion: import.parent_scope.expansion,
259 /// Define the name or return the existing binding if there is a collision.
260 pub(crate) fn try_define(
264 binding: &'a NameBinding<'a>,
265 ) -> Result<(), &'a NameBinding<'a>> {
266 let res = binding.res();
267 self.check_reserved_macro_name(key.ident, res);
268 self.set_binding_parent_module(binding, module);
269 self.update_resolution(module, key, |this, resolution| {
270 if let Some(old_binding) = resolution.binding {
271 if res == Res::Err && old_binding.res() != Res::Err {
272 // Do not override real bindings with `Res::Err`s from error recovery.
275 match (old_binding.is_glob_import(), binding.is_glob_import()) {
277 if res != old_binding.res() {
278 resolution.binding = Some(this.ambiguity(
279 AmbiguityKind::GlobVsGlob,
283 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
284 // We are glob-importing the same item but with greater visibility.
285 resolution.binding = Some(binding);
288 (old_glob @ true, false) | (old_glob @ false, true) => {
289 let (glob_binding, nonglob_binding) =
290 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
291 if glob_binding.res() != nonglob_binding.res()
293 && nonglob_binding.expansion != LocalExpnId::ROOT
295 resolution.binding = Some(this.ambiguity(
296 AmbiguityKind::GlobVsExpanded,
301 resolution.binding = Some(nonglob_binding);
303 resolution.shadowed_glob = Some(glob_binding);
306 return Err(old_binding);
310 resolution.binding = Some(binding);
320 primary_binding: &'a NameBinding<'a>,
321 secondary_binding: &'a NameBinding<'a>,
322 ) -> &'a NameBinding<'a> {
323 self.arenas.alloc_name_binding(NameBinding {
324 ambiguity: Some((secondary_binding, kind)),
325 ..primary_binding.clone()
329 // Use `f` to mutate the resolution of the name in the module.
330 // If the resolution becomes a success, define it in the module's glob importers.
331 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
333 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
335 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
336 // during which the resolution might end up getting re-defined via a glob cycle.
338 let resolution = &mut *self.resolution(module, key).borrow_mut();
339 let old_binding = resolution.binding();
341 let t = f(self, resolution);
343 match resolution.binding() {
344 _ if old_binding.is_some() => return t,
346 Some(binding) => match old_binding {
347 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
353 // Define `binding` in `module`s glob importers.
354 for import in module.glob_importers.borrow_mut().iter() {
355 let mut ident = key.ident;
356 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
357 Some(Some(def)) => self.expn_def_scope(def),
358 Some(None) => import.parent_scope.module,
361 if self.is_accessible_from(binding.vis, scope) {
362 let imported_binding = self.import(binding, import);
363 let key = BindingKey { ident, ..key };
364 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
371 // Define a dummy resolution containing a `Res::Err` as a placeholder for a failed resolution,
372 // also mark such failed imports as used to avoid duplicate diagnostics.
373 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
374 if let ImportKind::Single { target, ref target_bindings, .. } = import.kind {
375 if target_bindings.iter().any(|binding| binding.get().is_some()) {
376 return; // Has resolution, do not create the dummy binding
378 let dummy_binding = self.dummy_binding;
379 let dummy_binding = self.import(dummy_binding, import);
380 self.per_ns(|this, ns| {
381 let key = this.new_key(target, ns);
382 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
384 self.record_use(target, dummy_binding, false);
385 } else if import.imported_module.get().is_none() {
386 import.used.set(true);
387 if let Some(id) = import.id() {
388 self.used_imports.insert(id);
394 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
395 /// import errors within the same use tree into a single diagnostic.
396 #[derive(Debug, Clone)]
397 struct UnresolvedImportError {
399 label: Option<String>,
400 note: Option<String>,
401 suggestion: Option<Suggestion>,
402 candidate: Option<Vec<ImportSuggestion>>,
405 pub struct ImportResolver<'a, 'b> {
406 pub r: &'a mut Resolver<'b>,
409 impl<'a, 'b> ImportResolver<'a, 'b> {
412 // This is a fixed-point algorithm. We resolve imports until our efforts
413 // are stymied by an unresolved import; then we bail out of the current
414 // module and continue. We terminate successfully once no more imports
415 // remain or unsuccessfully when no forward progress in resolving imports
418 /// Resolves all imports for the crate. This method performs the fixed-
420 pub fn resolve_imports(&mut self) {
421 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
422 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
423 prev_num_indeterminates = self.r.indeterminate_imports.len();
424 for import in mem::take(&mut self.r.indeterminate_imports) {
425 match self.resolve_import(&import) {
426 true => self.r.determined_imports.push(import),
427 false => self.r.indeterminate_imports.push(import),
433 pub fn finalize_imports(&mut self) {
434 for module in self.r.arenas.local_modules().iter() {
435 self.finalize_resolutions_in(module);
438 let mut seen_spans = FxHashSet::default();
439 let mut errors = vec![];
440 let mut prev_root_id: NodeId = NodeId::from_u32(0);
441 let determined_imports = mem::take(&mut self.r.determined_imports);
442 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
444 for (is_indeterminate, import) in determined_imports
447 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
449 let unresolved_import_error = self.finalize_import(import);
451 // If this import is unresolved then create a dummy import
452 // resolution for it so that later resolve stages won't complain.
453 self.r.import_dummy_binding(import);
455 if let Some(err) = unresolved_import_error {
456 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
457 if source.name == kw::SelfLower {
458 // Silence `unresolved import` error if E0429 is already emitted
459 if let Err(Determined) = source_bindings.value_ns.get() {
465 if prev_root_id.as_u32() != 0
466 && prev_root_id.as_u32() != import.root_id.as_u32()
467 && !errors.is_empty()
469 // In the case of a new import line, throw a diagnostic message
470 // for the previous line.
471 self.throw_unresolved_import_error(errors);
474 if seen_spans.insert(err.span) {
475 let path = import_path_to_string(
476 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
480 errors.push((path, err));
481 prev_root_id = import.root_id;
483 } else if is_indeterminate {
484 let path = import_path_to_string(
485 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
489 let err = UnresolvedImportError {
496 if path.contains("::") {
497 errors.push((path, err))
502 if !errors.is_empty() {
503 self.throw_unresolved_import_error(errors);
507 fn throw_unresolved_import_error(&self, errors: Vec<(String, UnresolvedImportError)>) {
508 if errors.is_empty() {
512 /// Upper limit on the number of `span_label` messages.
513 const MAX_LABEL_COUNT: usize = 10;
515 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
516 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
517 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
519 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
521 if let Some((_, UnresolvedImportError { note: Some(note), .. })) = errors.iter().last() {
525 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
526 if let Some(label) = err.label {
527 diag.span_label(err.span, label);
530 if let Some((suggestions, msg, applicability)) = err.suggestion {
531 if suggestions.is_empty() {
535 diag.multipart_suggestion(&msg, suggestions, applicability);
538 if let Some(candidate) = &err.candidate {
552 /// Attempts to resolve the given import, returning true if its resolution is determined.
553 /// If successful, the resolved bindings are written into the module.
554 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
556 "(resolving import for module) resolving import `{}::...` in `{}`",
557 Segment::names_to_string(&import.module_path),
558 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
561 let module = if let Some(module) = import.imported_module.get() {
564 // For better failure detection, pretend that the import will
565 // not define any names while resolving its module path.
566 let orig_vis = import.vis.take();
568 self.r.maybe_resolve_path(&import.module_path, None, &import.parent_scope);
569 import.vis.set(orig_vis);
572 PathResult::Module(module) => module,
573 PathResult::Indeterminate => return false,
574 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
578 import.imported_module.set(Some(module));
579 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
587 } => (source, target, source_bindings, target_bindings, type_ns_only),
588 ImportKind::Glob { .. } => {
589 self.resolve_glob_import(import);
595 let mut indeterminate = false;
596 self.r.per_ns(|this, ns| {
597 if !type_ns_only || ns == TypeNS {
598 if let Err(Undetermined) = source_bindings[ns].get() {
599 // For better failure detection, pretend that the import will
600 // not define any names while resolving its module path.
601 let orig_vis = import.vis.take();
602 let binding = this.resolve_ident_in_module(
606 &import.parent_scope,
610 import.vis.set(orig_vis);
611 source_bindings[ns].set(binding);
616 let parent = import.parent_scope.module;
617 match source_bindings[ns].get() {
618 Err(Undetermined) => indeterminate = true,
619 // Don't update the resolution, because it was never added.
620 Err(Determined) if target.name == kw::Underscore => {}
621 Ok(binding) if binding.is_importable() => {
622 let imported_binding = this.import(binding, import);
623 target_bindings[ns].set(Some(imported_binding));
624 this.define(parent, target, ns, imported_binding);
626 source_binding @ (Ok(..) | Err(Determined)) => {
627 if source_binding.is_ok() {
628 let msg = format!("`{}` is not directly importable", target);
629 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
630 .span_label(import.span, "cannot be imported directly")
633 let key = this.new_key(target, ns);
634 this.update_resolution(parent, key, |_, resolution| {
635 resolution.single_imports.remove(&Interned::new_unchecked(import));
645 /// Performs final import resolution, consistency checks and error reporting.
647 /// Optionally returns an unresolved import error. This error is buffered and used to
648 /// consolidate multiple unresolved import errors into a single diagnostic.
649 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
650 let orig_vis = import.vis.take();
651 let ignore_binding = match &import.kind {
652 ImportKind::Single { target_bindings, .. } => target_bindings[TypeNS].get(),
655 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
656 let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span);
657 let path_res = self.r.resolve_path(
660 &import.parent_scope,
665 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
666 import.vis.set(orig_vis);
667 let module = match path_res {
668 PathResult::Module(module) => {
669 // Consistency checks, analogous to `finalize_macro_resolutions`.
670 if let Some(initial_module) = import.imported_module.get() {
671 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
672 span_bug!(import.span, "inconsistent resolution for an import");
674 } else if self.r.privacy_errors.is_empty() {
675 let msg = "cannot determine resolution for the import";
676 let msg_note = "import resolution is stuck, try simplifying other imports";
677 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
682 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
684 assert!(import.imported_module.get().is_none());
686 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
690 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
692 assert!(import.imported_module.get().is_none());
693 let err = match self.make_path_suggestion(
695 import.module_path.clone(),
696 &import.parent_scope,
698 Some((suggestion, note)) => UnresolvedImportError {
703 vec![(span, Segment::names_to_string(&suggestion))],
704 String::from("a similar path exists"),
705 Applicability::MaybeIncorrect,
709 None => UnresolvedImportError {
721 PathResult::NonModule(_) => {
723 assert!(import.imported_module.get().is_none());
725 // The error was already reported earlier.
728 PathResult::Indeterminate => unreachable!(),
731 let (ident, target, source_bindings, target_bindings, type_ns_only, import_id) =
741 } => (source, target, source_bindings, target_bindings, type_ns_only, id),
742 ImportKind::Glob { is_prelude, ref max_vis, id } => {
743 if import.module_path.len() <= 1 {
744 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
745 // 2 segments, so the `resolve_path` above won't trigger it.
746 let mut full_path = import.module_path.clone();
747 full_path.push(Segment::from_ident(Ident::empty()));
748 self.r.lint_if_path_starts_with_module(Some(finalize), &full_path, None);
751 if let ModuleOrUniformRoot::Module(module) = module {
752 if ptr::eq(module, import.parent_scope.module) {
753 // Importing a module into itself is not allowed.
754 return Some(UnresolvedImportError {
756 label: Some(String::from(
757 "cannot glob-import a module into itself",
766 && let Some(max_vis) = max_vis.get()
767 && !max_vis.is_at_least(import.expect_vis(), &*self.r)
769 let msg = "glob import doesn't reexport anything because no candidate is public enough";
770 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, id, import.span, msg);
777 let mut all_ns_err = true;
778 self.r.per_ns(|this, ns| {
779 if !type_ns_only || ns == TypeNS {
780 let orig_vis = import.vis.take();
781 let binding = this.resolve_ident_in_module(
785 &import.parent_scope,
786 Some(Finalize { report_private: false, ..finalize }),
787 target_bindings[ns].get(),
789 import.vis.set(orig_vis);
793 // Consistency checks, analogous to `finalize_macro_resolutions`.
794 let initial_res = source_bindings[ns].get().map(|initial_binding| {
796 if let Some(target_binding) = target_bindings[ns].get() {
797 if target.name == kw::Underscore
798 && initial_binding.is_extern_crate()
799 && !initial_binding.is_import()
804 import.module_path.is_empty(),
808 initial_binding.res()
810 let res = binding.res();
811 if let Ok(initial_res) = initial_res {
812 if res != initial_res && this.ambiguity_errors.is_empty() {
813 span_bug!(import.span, "inconsistent resolution for an import");
815 } else if res != Res::Err
816 && this.ambiguity_errors.is_empty()
817 && this.privacy_errors.is_empty()
819 let msg = "cannot determine resolution for the import";
821 "import resolution is stuck, try simplifying other imports";
822 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
826 // FIXME: This assert may fire if public glob is later shadowed by a private
827 // single import (see test `issue-55884-2.rs`). In theory single imports should
828 // always block globs, even if they are not yet resolved, so that this kind of
829 // self-inconsistent resolution never happens.
830 // Re-enable the assert when the issue is fixed.
831 // assert!(result[ns].get().is_err());
838 let mut all_ns_failed = true;
839 self.r.per_ns(|this, ns| {
840 if !type_ns_only || ns == TypeNS {
841 let binding = this.resolve_ident_in_module(
845 &import.parent_scope,
850 all_ns_failed = false;
855 return if all_ns_failed {
856 let resolutions = match module {
857 ModuleOrUniformRoot::Module(module) => {
858 Some(self.r.resolutions(module).borrow())
862 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
863 let names = resolutions
864 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
867 } // Never suggest the same name
868 match *resolution.borrow() {
869 NameResolution { binding: Some(name_binding), .. } => {
870 match name_binding.kind {
871 NameBindingKind::Import { binding, .. } => {
873 // Never suggest the name that has binding error
874 // i.e., the name that cannot be previously resolved
875 NameBindingKind::Res(Res::Err) => None,
882 NameResolution { ref single_imports, .. }
883 if single_imports.is_empty() =>
890 .collect::<Vec<Symbol>>();
893 find_best_match_for_name(&names, ident.name, None).map(|suggestion| {
895 vec![(ident.span, suggestion.to_string())],
896 String::from("a similar name exists in the module"),
897 Applicability::MaybeIncorrect,
901 let (suggestion, note) =
902 match self.check_for_module_export_macro(import, module, ident) {
903 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
904 _ => (lev_suggestion, None),
907 let label = match module {
908 ModuleOrUniformRoot::Module(module) => {
909 let module_str = module_to_string(module);
910 if let Some(module_str) = module_str {
911 format!("no `{}` in `{}`", ident, module_str)
913 format!("no `{}` in the root", ident)
917 if !ident.is_path_segment_keyword() {
918 format!("no external crate `{}`", ident)
920 // HACK(eddyb) this shows up for `self` & `super`, which
921 // should work instead - for now keep the same error message.
922 format!("no `{}` in the root", ident)
927 let parent_suggestion =
928 self.r.lookup_import_candidates(ident, TypeNS, &import.parent_scope, |_| true);
930 Some(UnresolvedImportError {
935 candidate: if !parent_suggestion.is_empty() {
936 Some(parent_suggestion)
942 // `resolve_ident_in_module` reported a privacy error.
947 let mut reexport_error = None;
948 let mut any_successful_reexport = false;
949 let mut crate_private_reexport = false;
950 self.r.per_ns(|this, ns| {
951 if let Ok(binding) = source_bindings[ns].get() {
952 if !binding.vis.is_at_least(import.expect_vis(), &*this) {
953 reexport_error = Some((ns, binding));
954 if let ty::Visibility::Restricted(binding_def_id) = binding.vis {
955 if binding_def_id.is_top_level_module() {
956 crate_private_reexport = true;
960 any_successful_reexport = true;
965 // All namespaces must be re-exported with extra visibility for an error to occur.
966 if !any_successful_reexport {
967 let (ns, binding) = reexport_error.unwrap();
968 if pub_use_of_private_extern_crate_hack(import, binding) {
970 "extern crate `{}` is private, and cannot be \
971 re-exported (error E0365), consider declaring with \
975 self.r.lint_buffer.buffer_lint(
976 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
982 let error_msg = if crate_private_reexport {
984 "`{}` is only public within the crate, and cannot be re-exported outside",
988 format!("`{}` is private, and cannot be re-exported", ident)
992 let label_msg = if crate_private_reexport {
993 format!("re-export of crate public `{}`", ident)
995 format!("re-export of private `{}`", ident)
998 struct_span_err!(self.r.session, import.span, E0365, "{}", error_msg)
999 .span_label(import.span, label_msg)
1000 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1004 struct_span_err!(self.r.session, import.span, E0364, "{error_msg}");
1005 match binding.kind {
1006 NameBindingKind::Res(Res::Def(DefKind::Macro(_), def_id))
1007 // exclude decl_macro
1008 if self.r.get_macro_by_def_id(def_id).macro_rules =>
1012 "consider adding a `#[macro_export]` to the macro in the imported module",
1019 "consider marking `{ident}` as `pub` in the imported module"
1029 if import.module_path.len() <= 1 {
1030 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1031 // 2 segments, so the `resolve_path` above won't trigger it.
1032 let mut full_path = import.module_path.clone();
1033 full_path.push(Segment::from_ident(ident));
1034 self.r.per_ns(|this, ns| {
1035 if let Ok(binding) = source_bindings[ns].get() {
1036 this.lint_if_path_starts_with_module(Some(finalize), &full_path, Some(binding));
1041 // Record what this import resolves to for later uses in documentation,
1042 // this may resolve to either a value or a type, but for documentation
1043 // purposes it's good enough to just favor one over the other.
1044 self.r.per_ns(|this, ns| {
1045 if let Ok(binding) = source_bindings[ns].get() {
1046 this.import_res_map.entry(import_id).or_default()[ns] = Some(binding.res());
1050 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1052 debug!("(resolving single import) successfully resolved import");
1056 fn check_for_redundant_imports(
1059 import: &'b Import<'b>,
1060 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1061 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1064 // This function is only called for single imports.
1065 let ImportKind::Single { id, .. } = import.kind else { unreachable!() };
1067 // Skip if the import was produced by a macro.
1068 if import.parent_scope.expansion != LocalExpnId::ROOT {
1072 // Skip if we are inside a named module (in contrast to an anonymous
1073 // module defined by a block).
1074 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1078 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1080 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1082 self.r.per_ns(|this, ns| {
1083 if let Ok(binding) = source_bindings[ns].get() {
1084 if binding.res() == Res::Err {
1088 match this.early_resolve_ident_in_lexical_scope(
1090 ScopeSet::All(ns, false),
1091 &import.parent_scope,
1094 target_bindings[ns].get(),
1096 Ok(other_binding) => {
1097 is_redundant[ns] = Some(
1098 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1100 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1102 Err(_) => is_redundant[ns] = Some(false),
1107 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1109 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1110 redundant_spans.sort();
1111 redundant_spans.dedup();
1112 self.r.lint_buffer.buffer_lint_with_diagnostic(
1116 &format!("the item `{}` is imported redundantly", ident),
1117 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1122 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1123 // This function is only called for glob imports.
1124 let ImportKind::Glob { id, is_prelude, .. } = import.kind else { unreachable!() };
1126 let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
1127 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1131 if module.is_trait() {
1132 self.r.session.span_err(import.span, "items in traits are not importable");
1134 } else if ptr::eq(module, import.parent_scope.module) {
1136 } else if is_prelude {
1137 self.r.prelude = Some(module);
1141 // Add to module's glob_importers
1142 module.glob_importers.borrow_mut().push(import);
1144 // Ensure that `resolutions` isn't borrowed during `try_define`,
1145 // since it might get updated via a glob cycle.
1148 .resolutions(module)
1151 .filter_map(|(key, resolution)| {
1152 resolution.borrow().binding().map(|binding| (*key, binding))
1154 .collect::<Vec<_>>();
1155 for (mut key, binding) in bindings {
1156 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1157 Some(Some(def)) => self.r.expn_def_scope(def),
1158 Some(None) => import.parent_scope.module,
1161 if self.r.is_accessible_from(binding.vis, scope) {
1162 let imported_binding = self.r.import(binding, import);
1163 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1167 // Record the destination of this import
1168 self.r.record_partial_res(id, PartialRes::new(module.res().unwrap()));
1171 // Miscellaneous post-processing, including recording re-exports,
1172 // reporting conflicts, and reporting unresolved imports.
1173 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1174 // Since import resolution is finished, globs will not define any more names.
1175 *module.globs.borrow_mut() = Vec::new();
1177 if let Some(def_id) = module.opt_def_id() {
1178 let mut reexports = Vec::new();
1180 module.for_each_child(self.r, |this, ident, _, binding| {
1181 if let Some(res) = this.is_reexport(binding) {
1182 reexports.push(ModChild {
1192 if !reexports.is_empty() {
1193 // Call to `expect_local` should be fine because current
1194 // code is only called for local modules.
1195 self.r.reexport_map.insert(def_id.expect_local(), reexports);
1201 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1202 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1203 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1204 if let Some(pos) = pos {
1205 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1206 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1208 let names = if global { &names[1..] } else { names };
1209 if names.is_empty() {
1210 import_kind_to_string(import_kind)
1214 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1215 import_kind_to_string(import_kind),
1221 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1223 ImportKind::Single { source, .. } => source.to_string(),
1224 ImportKind::Glob { .. } => "*".to_string(),
1225 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1226 ImportKind::MacroUse => "#[macro_use]".to_string(),
1227 ImportKind::MacroExport => "#[macro_export]".to_string(),