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, *};
6 use crate::{module_to_string, names_to_string};
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 /// Additional `NodeId`s allocated to a `ast::UseTree` for automatically generated `use` statement
48 /// (eg. implicit struct constructors)
49 additional_ids: (NodeId, NodeId),
53 max_vis: Cell<Option<ty::Visibility>>, // The visibility of the greatest re-export.
54 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
57 source: Option<Symbol>,
63 /// Manually implement `Debug` for `ImportKind` because the `source/target_bindings`
64 /// contain `Cell`s which can introduce infinite loops while printing.
65 impl<'a> std::fmt::Debug for ImportKind<'a> {
66 fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
75 // Ignore the following to avoid an infinite loop while printing.
79 .debug_struct("Single")
80 .field("source", source)
81 .field("target", target)
82 .field("type_ns_only", type_ns_only)
83 .field("nested", nested)
84 .field("additional_ids", additional_ids)
85 .finish_non_exhaustive(),
86 Glob { ref is_prelude, ref max_vis } => f
88 .field("is_prelude", is_prelude)
89 .field("max_vis", max_vis)
91 ExternCrate { ref source, ref target } => f
92 .debug_struct("ExternCrate")
93 .field("source", source)
94 .field("target", target)
96 MacroUse => f.debug_struct("MacroUse").finish(),
102 #[derive(Debug, Clone)]
103 pub(crate) struct Import<'a> {
104 pub kind: ImportKind<'a>,
106 /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`.
108 /// In the case where the `Import` was expanded from a "nested" use tree,
109 /// this id is the ID of the leaf tree. For example:
111 /// ```ignore (pacify the merciless tidy)
112 /// use foo::bar::{a, b}
115 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
116 /// for `a` in this field.
119 /// The `id` of the "root" use-kind -- this is always the same as
120 /// `id` except in the case of "nested" use trees, in which case
121 /// it will be the `id` of the root use tree. e.g., in the example
122 /// from `id`, this would be the ID of the `use foo::bar`
126 /// Span of the entire use statement.
129 /// Span of the entire use statement with attributes.
130 pub use_span_with_attributes: Span,
132 /// Did the use statement have any attributes?
133 pub has_attributes: bool,
135 /// Span of this use tree.
138 /// Span of the *root* use tree (see `root_id`).
141 pub parent_scope: ParentScope<'a>,
142 pub module_path: Vec<Segment>,
143 /// The resolution of `module_path`.
144 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
145 pub vis: Cell<Option<ty::Visibility>>,
146 pub used: Cell<bool>,
149 impl<'a> Import<'a> {
150 pub fn is_glob(&self) -> bool {
151 matches!(self.kind, ImportKind::Glob { .. })
154 pub fn is_nested(&self) -> bool {
156 ImportKind::Single { nested, .. } => nested,
161 pub(crate) fn expect_vis(&self) -> ty::Visibility {
162 self.vis.get().expect("encountered cleared import visibility")
166 /// Records information about the resolution of a name in a namespace of a module.
167 #[derive(Clone, Default, Debug)]
168 pub(crate) struct NameResolution<'a> {
169 /// Single imports that may define the name in the namespace.
170 /// Imports are arena-allocated, so it's ok to use pointers as keys.
171 pub single_imports: FxHashSet<Interned<'a, Import<'a>>>,
172 /// The least shadowable known binding for this name, or None if there are no known bindings.
173 pub binding: Option<&'a NameBinding<'a>>,
174 pub shadowed_glob: Option<&'a NameBinding<'a>>,
177 impl<'a> NameResolution<'a> {
178 // Returns the binding for the name if it is known or None if it not known.
179 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
180 self.binding.and_then(|binding| {
181 if !binding.is_glob_import() || self.single_imports.is_empty() {
189 pub(crate) fn add_single_import(&mut self, import: &'a Import<'a>) {
190 self.single_imports.insert(Interned::new_unchecked(import));
194 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
195 // are permitted for backward-compatibility under a deprecation lint.
196 fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
197 match (&import.kind, &binding.kind) {
199 ImportKind::Single { .. },
200 NameBindingKind::Import {
201 import: Import { kind: ImportKind::ExternCrate { .. }, .. },
204 ) => import.expect_vis().is_public(),
209 impl<'a> Resolver<'a> {
210 // Given a binding and an import that resolves to it,
211 // return the corresponding binding defined by the import.
212 pub(crate) fn import(
214 binding: &'a NameBinding<'a>,
215 import: &'a Import<'a>,
216 ) -> &'a NameBinding<'a> {
217 let import_vis = import.expect_vis().to_def_id();
218 let vis = if binding.vis.is_at_least(import_vis, self)
219 || pub_use_of_private_extern_crate_hack(import, binding)
226 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
228 || max_vis.get().map_or(true, |max_vis| vis.is_at_least(max_vis, self))
230 max_vis.set(Some(vis.expect_local()))
234 self.arenas.alloc_name_binding(NameBinding {
235 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
239 expansion: import.parent_scope.expansion,
243 // Define the name or return the existing binding if there is a collision.
244 pub(crate) fn try_define(
248 binding: &'a NameBinding<'a>,
249 ) -> Result<(), &'a NameBinding<'a>> {
250 let res = binding.res();
251 self.check_reserved_macro_name(key.ident, res);
252 self.set_binding_parent_module(binding, module);
253 self.update_resolution(module, key, |this, resolution| {
254 if let Some(old_binding) = resolution.binding {
256 // Do not override real bindings with `Res::Err`s from error recovery.
259 match (old_binding.is_glob_import(), binding.is_glob_import()) {
261 if res != old_binding.res() {
262 resolution.binding = Some(this.ambiguity(
263 AmbiguityKind::GlobVsGlob,
267 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
268 // We are glob-importing the same item but with greater visibility.
269 resolution.binding = Some(binding);
272 (old_glob @ true, false) | (old_glob @ false, true) => {
273 let (glob_binding, nonglob_binding) =
274 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
275 if glob_binding.res() != nonglob_binding.res()
277 && nonglob_binding.expansion != LocalExpnId::ROOT
279 resolution.binding = Some(this.ambiguity(
280 AmbiguityKind::GlobVsExpanded,
285 resolution.binding = Some(nonglob_binding);
287 resolution.shadowed_glob = Some(glob_binding);
290 return Err(old_binding);
294 resolution.binding = Some(binding);
304 primary_binding: &'a NameBinding<'a>,
305 secondary_binding: &'a NameBinding<'a>,
306 ) -> &'a NameBinding<'a> {
307 self.arenas.alloc_name_binding(NameBinding {
308 ambiguity: Some((secondary_binding, kind)),
309 ..primary_binding.clone()
313 // Use `f` to mutate the resolution of the name in the module.
314 // If the resolution becomes a success, define it in the module's glob importers.
315 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
317 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
319 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
320 // during which the resolution might end up getting re-defined via a glob cycle.
322 let resolution = &mut *self.resolution(module, key).borrow_mut();
323 let old_binding = resolution.binding();
325 let t = f(self, resolution);
327 match resolution.binding() {
328 _ if old_binding.is_some() => return t,
330 Some(binding) => match old_binding {
331 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
337 // Define `binding` in `module`s glob importers.
338 for import in module.glob_importers.borrow_mut().iter() {
339 let mut ident = key.ident;
340 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
341 Some(Some(def)) => self.expn_def_scope(def),
342 Some(None) => import.parent_scope.module,
345 if self.is_accessible_from(binding.vis, scope) {
346 let imported_binding = self.import(binding, import);
347 let key = BindingKey { ident, ..key };
348 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
355 // Define a dummy resolution containing a `Res::Err` as a placeholder for a failed resolution,
356 // also mark such failed imports as used to avoid duplicate diagnostics.
357 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
358 if let ImportKind::Single { target, ref target_bindings, .. } = import.kind {
359 if target_bindings.iter().any(|binding| binding.get().is_some()) {
360 return; // Has resolution, do not create the dummy binding
362 let dummy_binding = self.dummy_binding;
363 let dummy_binding = self.import(dummy_binding, import);
364 self.per_ns(|this, ns| {
365 let key = this.new_key(target, ns);
366 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
368 self.record_use(target, dummy_binding, false);
369 } else if import.imported_module.get().is_none() {
370 import.used.set(true);
371 self.used_imports.insert(import.id);
375 /// Take primary and additional node IDs from an import and select one that corresponds to the
376 /// given namespace. The logic must match the corresponding logic from `fn lower_use_tree` that
377 /// assigns resolutons to IDs.
378 pub(crate) fn import_id_for_ns(&self, import: &Import<'_>, ns: Namespace) -> NodeId {
379 if let ImportKind::Single { additional_ids: (id1, id2), .. } = import.kind {
380 if let Some(resolutions) = self.import_res_map.get(&import.id) {
381 assert!(resolutions[ns].is_some(), "incorrectly finalized import");
384 ValueNS => match resolutions.type_ns {
388 MacroNS => match (resolutions.type_ns, resolutions.value_ns) {
389 (Some(_), Some(_)) => id2,
390 (Some(_), None) | (None, Some(_)) => id1,
391 (None, None) => import.id,
401 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
402 /// import errors within the same use tree into a single diagnostic.
403 #[derive(Debug, Clone)]
404 struct UnresolvedImportError {
406 label: Option<String>,
407 note: Option<String>,
408 suggestion: Option<Suggestion>,
411 pub struct ImportResolver<'a, 'b> {
412 pub r: &'a mut Resolver<'b>,
415 impl<'a, 'b> ImportResolver<'a, 'b> {
418 // This is a fixed-point algorithm. We resolve imports until our efforts
419 // are stymied by an unresolved import; then we bail out of the current
420 // module and continue. We terminate successfully once no more imports
421 // remain or unsuccessfully when no forward progress in resolving imports
424 /// Resolves all imports for the crate. This method performs the fixed-
426 pub fn resolve_imports(&mut self) {
427 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
428 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
429 prev_num_indeterminates = self.r.indeterminate_imports.len();
430 for import in mem::take(&mut self.r.indeterminate_imports) {
431 match self.resolve_import(&import) {
432 true => self.r.determined_imports.push(import),
433 false => self.r.indeterminate_imports.push(import),
439 pub fn finalize_imports(&mut self) {
440 for module in self.r.arenas.local_modules().iter() {
441 self.finalize_resolutions_in(module);
444 let mut seen_spans = FxHashSet::default();
445 let mut errors = vec![];
446 let mut prev_root_id: NodeId = NodeId::from_u32(0);
447 let determined_imports = mem::take(&mut self.r.determined_imports);
448 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
450 for (is_indeterminate, import) in determined_imports
453 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
455 let unresolved_import_error = self.finalize_import(import);
457 // If this import is unresolved then create a dummy import
458 // resolution for it so that later resolve stages won't complain.
459 self.r.import_dummy_binding(import);
461 if let Some(err) = unresolved_import_error {
462 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
463 if source.name == kw::SelfLower {
464 // Silence `unresolved import` error if E0429 is already emitted
465 if let Err(Determined) = source_bindings.value_ns.get() {
471 if prev_root_id.as_u32() != 0
472 && prev_root_id.as_u32() != import.root_id.as_u32()
473 && !errors.is_empty()
475 // In the case of a new import line, throw a diagnostic message
476 // for the previous line.
477 self.throw_unresolved_import_error(errors, None);
480 if seen_spans.insert(err.span) {
481 let path = import_path_to_string(
482 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
486 errors.push((path, err));
487 prev_root_id = import.root_id;
489 } else if is_indeterminate {
490 let path = import_path_to_string(
491 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
495 let err = UnresolvedImportError {
501 if path.contains("::") {
502 errors.push((path, err))
507 if !errors.is_empty() {
508 self.throw_unresolved_import_error(errors, None);
512 fn throw_unresolved_import_error(
514 errors: Vec<(String, UnresolvedImportError)>,
515 span: Option<MultiSpan>,
517 /// Upper limit on the number of `span_label` messages.
518 const MAX_LABEL_COUNT: usize = 10;
520 let (span, msg) = if errors.is_empty() {
521 (span.unwrap(), "unresolved import".to_string())
523 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
525 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
527 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
532 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
534 if let Some((_, UnresolvedImportError { note: Some(note), .. })) = errors.iter().last() {
538 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
539 if let Some(label) = err.label {
540 diag.span_label(err.span, label);
543 if let Some((suggestions, msg, applicability)) = err.suggestion {
544 if suggestions.is_empty() {
548 diag.multipart_suggestion(&msg, suggestions, applicability);
555 /// Attempts to resolve the given import, returning true if its resolution is determined.
556 /// If successful, the resolved bindings are written into the module.
557 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
559 "(resolving import for module) resolving import `{}::...` in `{}`",
560 Segment::names_to_string(&import.module_path),
561 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
564 let module = if let Some(module) = import.imported_module.get() {
567 // For better failure detection, pretend that the import will
568 // not define any names while resolving its module path.
569 let orig_vis = import.vis.take();
571 self.r.maybe_resolve_path(&import.module_path, None, &import.parent_scope);
572 import.vis.set(orig_vis);
575 PathResult::Module(module) => module,
576 PathResult::Indeterminate => return false,
577 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
581 import.imported_module.set(Some(module));
582 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
590 } => (source, target, source_bindings, target_bindings, type_ns_only),
591 ImportKind::Glob { .. } => {
592 self.resolve_glob_import(import);
598 let mut indeterminate = false;
599 self.r.per_ns(|this, ns| {
600 if !type_ns_only || ns == TypeNS {
601 if let Err(Undetermined) = source_bindings[ns].get() {
602 // For better failure detection, pretend that the import will
603 // not define any names while resolving its module path.
604 let orig_vis = import.vis.take();
605 let binding = this.resolve_ident_in_module(
609 &import.parent_scope,
613 import.vis.set(orig_vis);
614 source_bindings[ns].set(binding);
619 let parent = import.parent_scope.module;
620 match source_bindings[ns].get() {
621 Err(Undetermined) => indeterminate = true,
622 // Don't update the resolution, because it was never added.
623 Err(Determined) if target.name == kw::Underscore => {}
624 Ok(binding) if binding.is_importable() => {
625 let imported_binding = this.import(binding, import);
626 target_bindings[ns].set(Some(imported_binding));
627 this.define(parent, target, ns, imported_binding);
629 source_binding @ (Ok(..) | Err(Determined)) => {
630 if source_binding.is_ok() {
631 let msg = format!("`{}` is not directly importable", target);
632 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
633 .span_label(import.span, "cannot be imported directly")
636 let key = this.new_key(target, ns);
637 this.update_resolution(parent, key, |_, resolution| {
638 resolution.single_imports.remove(&Interned::new_unchecked(import));
648 /// Performs final import resolution, consistency checks and error reporting.
650 /// Optionally returns an unresolved import error. This error is buffered and used to
651 /// consolidate multiple unresolved import errors into a single diagnostic.
652 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
653 let orig_vis = import.vis.take();
654 let ignore_binding = match &import.kind {
655 ImportKind::Single { target_bindings, .. } => target_bindings[TypeNS].get(),
658 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
659 let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span);
660 let path_res = self.r.resolve_path(
663 &import.parent_scope,
667 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
668 import.vis.set(orig_vis);
669 let module = match path_res {
670 PathResult::Module(module) => {
671 // Consistency checks, analogous to `finalize_macro_resolutions`.
672 if let Some(initial_module) = import.imported_module.get() {
673 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
674 span_bug!(import.span, "inconsistent resolution for an import");
676 } else if self.r.privacy_errors.is_empty() {
677 let msg = "cannot determine resolution for the import";
678 let msg_note = "import resolution is stuck, try simplifying other imports";
679 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
684 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
686 assert!(import.imported_module.get().is_none());
688 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
692 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
694 assert!(import.imported_module.get().is_none());
695 let err = match self.make_path_suggestion(
697 import.module_path.clone(),
698 &import.parent_scope,
700 Some((suggestion, note)) => UnresolvedImportError {
705 vec![(span, Segment::names_to_string(&suggestion))],
706 String::from("a similar path exists"),
707 Applicability::MaybeIncorrect,
710 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) = match import.kind {
739 } => (source, target, source_bindings, target_bindings, type_ns_only),
740 ImportKind::Glob { is_prelude, ref max_vis } => {
741 if import.module_path.len() <= 1 {
742 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
743 // 2 segments, so the `resolve_path` above won't trigger it.
744 let mut full_path = import.module_path.clone();
745 full_path.push(Segment::from_ident(Ident::empty()));
746 self.r.lint_if_path_starts_with_module(Some(finalize), &full_path, None);
749 if let ModuleOrUniformRoot::Module(module) = module {
750 if ptr::eq(module, import.parent_scope.module) {
751 // Importing a module into itself is not allowed.
752 return Some(UnresolvedImportError {
754 label: Some(String::from("cannot glob-import a module into itself")),
761 && let Some(max_vis) = max_vis.get()
762 && !max_vis.is_at_least(import.expect_vis(), &*self.r)
764 let msg = "glob import doesn't reexport anything because no candidate is public enough";
765 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
772 let mut all_ns_err = true;
773 self.r.per_ns(|this, ns| {
774 if !type_ns_only || ns == TypeNS {
775 let orig_vis = import.vis.take();
776 let binding = this.resolve_ident_in_module(
780 &import.parent_scope,
781 Some(Finalize { report_private: false, ..finalize }),
782 target_bindings[ns].get(),
784 import.vis.set(orig_vis);
788 // Consistency checks, analogous to `finalize_macro_resolutions`.
789 let initial_res = source_bindings[ns].get().map(|initial_binding| {
791 if let Some(target_binding) = target_bindings[ns].get() {
792 if target.name == kw::Underscore
793 && initial_binding.is_extern_crate()
794 && !initial_binding.is_import()
799 import.module_path.is_empty(),
803 initial_binding.res()
805 let res = binding.res();
806 if let Ok(initial_res) = initial_res {
807 if res != initial_res && this.ambiguity_errors.is_empty() {
808 span_bug!(import.span, "inconsistent resolution for an import");
810 } else if res != Res::Err
811 && this.ambiguity_errors.is_empty()
812 && this.privacy_errors.is_empty()
814 let msg = "cannot determine resolution for the import";
816 "import resolution is stuck, try simplifying other imports";
817 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
821 // FIXME: This assert may fire if public glob is later shadowed by a private
822 // single import (see test `issue-55884-2.rs`). In theory single imports should
823 // always block globs, even if they are not yet resolved, so that this kind of
824 // self-inconsistent resolution never happens.
825 // Re-enable the assert when the issue is fixed.
826 // assert!(result[ns].get().is_err());
833 let mut all_ns_failed = true;
834 self.r.per_ns(|this, ns| {
835 if !type_ns_only || ns == TypeNS {
836 let binding = this.resolve_ident_in_module(
840 &import.parent_scope,
845 all_ns_failed = false;
850 return if all_ns_failed {
851 let resolutions = match module {
852 ModuleOrUniformRoot::Module(module) => {
853 Some(self.r.resolutions(module).borrow())
857 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
858 let names = resolutions
859 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
862 } // Never suggest the same name
863 match *resolution.borrow() {
864 NameResolution { binding: Some(name_binding), .. } => {
865 match name_binding.kind {
866 NameBindingKind::Import { binding, .. } => {
868 // Never suggest the name that has binding error
869 // i.e., the name that cannot be previously resolved
870 NameBindingKind::Res(Res::Err, _) => None,
877 NameResolution { ref single_imports, .. }
878 if single_imports.is_empty() =>
885 .collect::<Vec<Symbol>>();
888 find_best_match_for_name(&names, ident.name, None).map(|suggestion| {
890 vec![(ident.span, suggestion.to_string())],
891 String::from("a similar name exists in the module"),
892 Applicability::MaybeIncorrect,
896 let (suggestion, note) =
897 match self.check_for_module_export_macro(import, module, ident) {
898 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
899 _ => (lev_suggestion, None),
902 let label = match module {
903 ModuleOrUniformRoot::Module(module) => {
904 let module_str = module_to_string(module);
905 if let Some(module_str) = module_str {
906 format!("no `{}` in `{}`", ident, module_str)
908 format!("no `{}` in the root", ident)
912 if !ident.is_path_segment_keyword() {
913 format!("no external crate `{}`", ident)
915 // HACK(eddyb) this shows up for `self` & `super`, which
916 // should work instead - for now keep the same error message.
917 format!("no `{}` in the root", ident)
922 Some(UnresolvedImportError {
929 // `resolve_ident_in_module` reported a privacy error.
934 let mut reexport_error = None;
935 let mut any_successful_reexport = false;
936 let mut crate_private_reexport = false;
937 self.r.per_ns(|this, ns| {
938 if let Ok(binding) = source_bindings[ns].get() {
939 if !binding.vis.is_at_least(import.expect_vis(), &*this) {
940 reexport_error = Some((ns, binding));
941 if let ty::Visibility::Restricted(binding_def_id) = binding.vis {
942 if binding_def_id.is_top_level_module() {
943 crate_private_reexport = true;
947 any_successful_reexport = true;
952 // All namespaces must be re-exported with extra visibility for an error to occur.
953 if !any_successful_reexport {
954 let (ns, binding) = reexport_error.unwrap();
955 if pub_use_of_private_extern_crate_hack(import, binding) {
957 "extern crate `{}` is private, and cannot be \
958 re-exported (error E0365), consider declaring with \
962 self.r.lint_buffer.buffer_lint(
963 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
969 let error_msg = if crate_private_reexport {
971 "`{}` is only public within the crate, and cannot be re-exported outside",
975 format!("`{}` is private, and cannot be re-exported", ident)
979 let label_msg = if crate_private_reexport {
980 format!("re-export of crate public `{}`", ident)
982 format!("re-export of private `{}`", ident)
985 struct_span_err!(self.r.session, import.span, E0365, "{}", error_msg)
986 .span_label(import.span, label_msg)
987 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
991 struct_span_err!(self.r.session, import.span, E0364, "{error_msg}");
993 NameBindingKind::Res(Res::Def(DefKind::Macro(_), def_id), _)
994 // exclude decl_macro
995 if self.r.get_macro_by_def_id(def_id).macro_rules =>
999 "consider adding a `#[macro_export]` to the macro in the imported module",
1006 "consider marking `{ident}` as `pub` in the imported module"
1016 if import.module_path.len() <= 1 {
1017 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1018 // 2 segments, so the `resolve_path` above won't trigger it.
1019 let mut full_path = import.module_path.clone();
1020 full_path.push(Segment::from_ident(ident));
1021 self.r.per_ns(|this, ns| {
1022 if let Ok(binding) = source_bindings[ns].get() {
1023 this.lint_if_path_starts_with_module(Some(finalize), &full_path, Some(binding));
1028 // Record what this import resolves to for later uses in documentation,
1029 // this may resolve to either a value or a type, but for documentation
1030 // purposes it's good enough to just favor one over the other.
1031 self.r.per_ns(|this, ns| {
1032 if let Ok(binding) = source_bindings[ns].get() {
1033 this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res());
1037 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1039 debug!("(resolving single import) successfully resolved import");
1043 fn check_for_redundant_imports(
1046 import: &'b Import<'b>,
1047 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1048 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1051 // Skip if the import was produced by a macro.
1052 if import.parent_scope.expansion != LocalExpnId::ROOT {
1056 // Skip if we are inside a named module (in contrast to an anonymous
1057 // module defined by a block).
1058 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1062 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1064 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1066 self.r.per_ns(|this, ns| {
1067 if let Ok(binding) = source_bindings[ns].get() {
1068 if binding.res() == Res::Err {
1072 match this.early_resolve_ident_in_lexical_scope(
1074 ScopeSet::All(ns, false),
1075 &import.parent_scope,
1078 target_bindings[ns].get(),
1080 Ok(other_binding) => {
1081 is_redundant[ns] = Some(
1082 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1084 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1086 Err(_) => is_redundant[ns] = Some(false),
1091 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1093 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1094 redundant_spans.sort();
1095 redundant_spans.dedup();
1096 self.r.lint_buffer.buffer_lint_with_diagnostic(
1100 &format!("the item `{}` is imported redundantly", ident),
1101 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1106 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1107 let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
1108 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1112 if module.is_trait() {
1113 self.r.session.span_err(import.span, "items in traits are not importable");
1115 } else if ptr::eq(module, import.parent_scope.module) {
1117 } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind {
1118 self.r.prelude = Some(module);
1122 // Add to module's glob_importers
1123 module.glob_importers.borrow_mut().push(import);
1125 // Ensure that `resolutions` isn't borrowed during `try_define`,
1126 // since it might get updated via a glob cycle.
1129 .resolutions(module)
1132 .filter_map(|(key, resolution)| {
1133 resolution.borrow().binding().map(|binding| (*key, binding))
1135 .collect::<Vec<_>>();
1136 for (mut key, binding) in bindings {
1137 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1138 Some(Some(def)) => self.r.expn_def_scope(def),
1139 Some(None) => import.parent_scope.module,
1142 if self.r.is_accessible_from(binding.vis, scope) {
1143 let imported_binding = self.r.import(binding, import);
1144 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1148 // Record the destination of this import
1149 self.r.record_partial_res(import.id, PartialRes::new(module.res().unwrap()));
1152 // Miscellaneous post-processing, including recording re-exports,
1153 // reporting conflicts, and reporting unresolved imports.
1154 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1155 // Since import resolution is finished, globs will not define any more names.
1156 *module.globs.borrow_mut() = Vec::new();
1158 if let Some(def_id) = module.opt_def_id() {
1159 let mut reexports = Vec::new();
1161 module.for_each_child(self.r, |this, ident, _, binding| {
1162 if let Some(res) = this.is_reexport(binding) {
1163 reexports.push(ModChild {
1173 if !reexports.is_empty() {
1174 // Call to `expect_local` should be fine because current
1175 // code is only called for local modules.
1176 self.r.reexport_map.insert(def_id.expect_local(), reexports);
1182 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1183 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1184 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1185 if let Some(pos) = pos {
1186 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1187 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1189 let names = if global { &names[1..] } else { names };
1190 if names.is_empty() {
1191 import_kind_to_string(import_kind)
1195 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1196 import_kind_to_string(import_kind),
1202 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1204 ImportKind::Single { source, .. } => source.to_string(),
1205 ImportKind::Glob { .. } => "*".to_string(),
1206 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1207 ImportKind::MacroUse => "#[macro_use]".to_string(),