1 //! A bunch of methods and structures more or less related to resolving imports.
3 use crate::diagnostics::Suggestion;
4 use crate::Determinacy::{self, *};
5 use crate::Namespace::{self, MacroNS, TypeNS};
6 use crate::{module_to_string, names_to_string};
7 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
8 use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment};
9 use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak};
10 use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
12 use rustc_ast::unwrap_or;
13 use rustc_ast::NodeId;
14 use rustc_ast_lowering::ResolverAstLowering;
15 use rustc_data_structures::fx::FxHashSet;
16 use rustc_data_structures::ptr_key::PtrKey;
17 use rustc_errors::{pluralize, struct_span_err, Applicability};
18 use rustc_hir::def::{self, PartialRes};
19 use rustc_hir::def_id::DefId;
20 use rustc_middle::hir::exports::Export;
22 use rustc_middle::{bug, span_bug};
23 use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
24 use rustc_session::lint::BuiltinLintDiagnostics;
25 use rustc_session::DiagnosticMessageId;
26 use rustc_span::hygiene::ExpnId;
27 use rustc_span::lev_distance::find_best_match_for_name;
28 use rustc_span::symbol::{kw, Ident, Symbol};
29 use rustc_span::{MultiSpan, Span};
36 type Res = def::Res<NodeId>;
38 /// Contains data for specific kinds of imports.
39 #[derive(Clone, Debug)]
40 pub enum ImportKind<'a> {
42 /// `source` in `use prefix::source as target`.
44 /// `target` in `use prefix::source as target`.
46 /// Bindings to which `source` refers to.
47 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
48 /// Bindings introduced by `target`.
49 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
50 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
52 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
57 max_vis: Cell<ty::Visibility>, // The visibility of the greatest re-export.
58 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
61 source: Option<Symbol>,
68 #[derive(Debug, Clone)]
69 crate struct Import<'a> {
70 pub kind: ImportKind<'a>,
72 /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`.
74 /// In the case where the `Import` was expanded from a "nested" use tree,
75 /// this id is the ID of the leaf tree. For example:
77 /// ```ignore (pacify the mercilous tidy)
78 /// use foo::bar::{a, b}
81 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
82 /// for `a` in this field.
85 /// The `id` of the "root" use-kind -- this is always the same as
86 /// `id` except in the case of "nested" use trees, in which case
87 /// it will be the `id` of the root use tree. e.g., in the example
88 /// from `id`, this would be the ID of the `use foo::bar`
92 /// Span of the entire use statement.
95 /// Span of the entire use statement with attributes.
96 pub use_span_with_attributes: Span,
98 /// Did the use statement have any attributes?
99 pub has_attributes: bool,
101 /// Span of this use tree.
104 /// Span of the *root* use tree (see `root_id`).
107 pub parent_scope: ParentScope<'a>,
108 pub module_path: Vec<Segment>,
109 /// The resolution of `module_path`.
110 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
111 pub vis: Cell<ty::Visibility>,
112 pub used: Cell<bool>,
115 impl<'a> Import<'a> {
116 pub fn is_glob(&self) -> bool {
117 matches!(self.kind, ImportKind::Glob { .. })
120 pub fn is_nested(&self) -> bool {
122 ImportKind::Single { nested, .. } => nested,
127 crate fn crate_lint(&self) -> CrateLint {
128 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
132 #[derive(Clone, Default, Debug)]
133 /// Records information about the resolution of a name in a namespace of a module.
134 pub struct NameResolution<'a> {
135 /// Single imports that may define the name in the namespace.
136 /// Imports are arena-allocated, so it's ok to use pointers as keys.
137 single_imports: FxHashSet<PtrKey<'a, Import<'a>>>,
138 /// The least shadowable known binding for this name, or None if there are no known bindings.
139 pub binding: Option<&'a NameBinding<'a>>,
140 shadowed_glob: Option<&'a NameBinding<'a>>,
143 impl<'a> NameResolution<'a> {
144 // Returns the binding for the name if it is known or None if it not known.
145 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
146 self.binding.and_then(|binding| {
147 if !binding.is_glob_import() || self.single_imports.is_empty() {
155 crate fn add_single_import(&mut self, import: &'a Import<'a>) {
156 self.single_imports.insert(PtrKey(import));
160 impl<'a> Resolver<'a> {
161 crate fn resolve_ident_in_module_unadjusted(
163 module: ModuleOrUniformRoot<'a>,
166 parent_scope: &ParentScope<'a>,
169 ) -> Result<&'a NameBinding<'a>, Determinacy> {
170 self.resolve_ident_in_module_unadjusted_ext(
179 .map_err(|(determinacy, _)| determinacy)
182 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
183 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
184 crate fn resolve_ident_in_module_unadjusted_ext(
186 module: ModuleOrUniformRoot<'a>,
189 parent_scope: &ParentScope<'a>,
190 restricted_shadowing: bool,
193 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
194 let module = match module {
195 ModuleOrUniformRoot::Module(module) => module,
196 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
197 assert!(!restricted_shadowing);
198 let binding = self.early_resolve_ident_in_lexical_scope(
200 ScopeSet::AbsolutePath(ns),
206 return binding.map_err(|determinacy| (determinacy, Weak::No));
208 ModuleOrUniformRoot::ExternPrelude => {
209 assert!(!restricted_shadowing);
210 return if ns != TypeNS {
211 Err((Determined, Weak::No))
212 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
214 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
215 // Macro-expanded `extern crate` items can add names to extern prelude.
216 Err((Undetermined, Weak::No))
218 Err((Determined, Weak::No))
221 ModuleOrUniformRoot::CurrentScope => {
222 assert!(!restricted_shadowing);
224 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
225 let module = self.resolve_crate_root(ident);
226 let binding = (module, ty::Visibility::Public, module.span, ExpnId::root())
227 .to_name_binding(self.arenas);
229 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
230 // FIXME: Implement these with renaming requirements so that e.g.
231 // `use super;` doesn't work, but `use super as name;` does.
232 // Fall through here to get an error from `early_resolve_...`.
236 let scopes = ScopeSet::All(ns, true);
237 let binding = self.early_resolve_ident_in_lexical_scope(
245 return binding.map_err(|determinacy| (determinacy, Weak::No));
249 let key = self.new_key(ident, ns);
251 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
253 if let Some(binding) = resolution.binding {
254 if !restricted_shadowing && binding.expansion != ExpnId::root() {
255 if let NameBindingKind::Res(_, true) = binding.kind {
256 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
261 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
262 if let Some(unusable_binding) = this.unusable_binding {
263 if ptr::eq(binding, unusable_binding) {
264 return Err((Determined, Weak::No));
267 // `extern crate` are always usable for backwards compatibility, see issue #37020,
268 // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
269 let usable = this.is_accessible_from(binding.vis, parent_scope.module)
270 || binding.is_extern_crate();
271 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
277 .and_then(|binding| {
278 // If the primary binding is unusable, search further and return the shadowed glob
279 // binding if it exists. What we really want here is having two separate scopes in
280 // a module - one for non-globs and one for globs, but until that's done use this
281 // hack to avoid inconsistent resolution ICEs during import validation.
282 if let Some(unusable_binding) = self.unusable_binding {
283 if ptr::eq(binding, unusable_binding) {
284 return resolution.shadowed_glob;
289 .ok_or((Determined, Weak::No))
290 .and_then(|binding| {
291 if self.last_import_segment && check_usable(self, binding).is_err() {
292 Err((Determined, Weak::No))
294 self.record_use(ident, ns, binding, restricted_shadowing);
296 if let Some(shadowed_glob) = resolution.shadowed_glob {
297 // Forbid expanded shadowing to avoid time travel.
298 if restricted_shadowing
299 && binding.expansion != ExpnId::root()
300 && binding.res() != shadowed_glob.res()
302 self.ambiguity_errors.push(AmbiguityError {
303 kind: AmbiguityKind::GlobVsExpanded,
307 misc1: AmbiguityErrorMisc::None,
308 misc2: AmbiguityErrorMisc::None,
313 if !(self.is_accessible_from(binding.vis, parent_scope.module) ||
314 // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
315 (self.last_import_segment && binding.is_extern_crate()))
317 self.privacy_errors.push(PrivacyError {
320 dedup_span: path_span,
329 // Items and single imports are not shadowable, if we have one, then it's determined.
330 if let Some(binding) = resolution.binding {
331 if !binding.is_glob_import() {
332 return check_usable(self, binding);
336 // --- From now on we either have a glob resolution or no resolution. ---
338 // Check if one of single imports can still define the name,
339 // if it can then our result is not determined and can be invalidated.
340 for single_import in &resolution.single_imports {
341 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
344 let module = unwrap_or!(
345 single_import.imported_module.get(),
346 return Err((Undetermined, Weak::No))
348 let ident = match single_import.kind {
349 ImportKind::Single { source, .. } => source,
352 match self.resolve_ident_in_module(
356 &single_import.parent_scope,
360 Err(Determined) => continue,
362 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
366 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
370 // So we have a resolution that's from a glob import. This resolution is determined
371 // if it cannot be shadowed by some new item/import expanded from a macro.
372 // This happens either if there are no unexpanded macros, or expanded names cannot
373 // shadow globs (that happens in macro namespace or with restricted shadowing).
375 // Additionally, any macro in any module can plant names in the root module if it creates
376 // `macro_export` macros, so the root module effectively has unresolved invocations if any
377 // module has unresolved invocations.
378 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
379 // progress, we have to ignore those potential unresolved invocations from other modules
380 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
381 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
382 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
383 if let Some(binding) = resolution.binding {
384 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
385 return check_usable(self, binding);
387 return Err((Undetermined, Weak::No));
391 // --- From now on we have no resolution. ---
393 // Now we are in situation when new item/import can appear only from a glob or a macro
394 // expansion. With restricted shadowing names from globs and macro expansions cannot
395 // shadow names from outer scopes, so we can freely fallback from module search to search
396 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
397 // scopes we return `Undetermined` with `Weak::Yes`.
399 // Check if one of unexpanded macros can still define the name,
400 // if it can then our "no resolution" result is not determined and can be invalidated.
401 if unexpanded_macros {
402 return Err((Undetermined, Weak::Yes));
405 // Check if one of glob imports can still define the name,
406 // if it can then our "no resolution" result is not determined and can be invalidated.
407 for glob_import in module.globs.borrow().iter() {
408 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
411 let module = match glob_import.imported_module.get() {
412 Some(ModuleOrUniformRoot::Module(module)) => module,
414 None => return Err((Undetermined, Weak::Yes)),
416 let tmp_parent_scope;
417 let (mut adjusted_parent_scope, mut ident) =
418 (parent_scope, ident.normalize_to_macros_2_0());
419 match ident.span.glob_adjust(module.expansion, glob_import.span) {
422 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
423 adjusted_parent_scope = &tmp_parent_scope;
428 let result = self.resolve_ident_in_module_unadjusted(
429 ModuleOrUniformRoot::Module(module),
432 adjusted_parent_scope,
438 Err(Determined) => continue,
440 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
444 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
448 // No resolution and no one else can define the name - determinate error.
449 Err((Determined, Weak::No))
452 // Given a binding and an import that resolves to it,
453 // return the corresponding binding defined by the import.
456 binding: &'a NameBinding<'a>,
457 import: &'a Import<'a>,
458 ) -> &'a NameBinding<'a> {
459 let vis = if binding.pseudo_vis().is_at_least(import.vis.get(), self) ||
460 // cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
461 !import.is_glob() && binding.is_extern_crate()
468 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
469 if vis == import.vis.get() || vis.is_at_least(max_vis.get(), self) {
474 self.arenas.alloc_name_binding(NameBinding {
475 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
479 expansion: import.parent_scope.expansion,
483 // Define the name or return the existing binding if there is a collision.
488 binding: &'a NameBinding<'a>,
489 ) -> Result<(), &'a NameBinding<'a>> {
490 let res = binding.res();
491 self.check_reserved_macro_name(key.ident, res);
492 self.set_binding_parent_module(binding, module);
493 self.update_resolution(module, key, |this, resolution| {
494 if let Some(old_binding) = resolution.binding {
496 // Do not override real bindings with `Res::Err`s from error recovery.
499 match (old_binding.is_glob_import(), binding.is_glob_import()) {
501 if res != old_binding.res() {
502 resolution.binding = Some(this.ambiguity(
503 AmbiguityKind::GlobVsGlob,
507 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
508 // We are glob-importing the same item but with greater visibility.
509 resolution.binding = Some(binding);
512 (old_glob @ true, false) | (old_glob @ false, true) => {
513 let (glob_binding, nonglob_binding) =
514 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
515 if glob_binding.res() != nonglob_binding.res()
517 && nonglob_binding.expansion != ExpnId::root()
519 resolution.binding = Some(this.ambiguity(
520 AmbiguityKind::GlobVsExpanded,
525 resolution.binding = Some(nonglob_binding);
527 resolution.shadowed_glob = Some(glob_binding);
530 return Err(old_binding);
534 resolution.binding = Some(binding);
544 primary_binding: &'a NameBinding<'a>,
545 secondary_binding: &'a NameBinding<'a>,
546 ) -> &'a NameBinding<'a> {
547 self.arenas.alloc_name_binding(NameBinding {
548 ambiguity: Some((secondary_binding, kind)),
549 ..primary_binding.clone()
553 // Use `f` to mutate the resolution of the name in the module.
554 // If the resolution becomes a success, define it in the module's glob importers.
555 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
557 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
559 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
560 // during which the resolution might end up getting re-defined via a glob cycle.
562 let resolution = &mut *self.resolution(module, key).borrow_mut();
563 let old_binding = resolution.binding();
565 let t = f(self, resolution);
567 match resolution.binding() {
568 _ if old_binding.is_some() => return t,
570 Some(binding) => match old_binding {
571 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
577 // Define `binding` in `module`s glob importers.
578 for import in module.glob_importers.borrow_mut().iter() {
579 let mut ident = key.ident;
580 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
581 Some(Some(def)) => self.macro_def_scope(def),
582 Some(None) => import.parent_scope.module,
585 if self.is_accessible_from(binding.vis, scope) {
586 let imported_binding = self.import(binding, import);
587 let key = BindingKey { ident, ..key };
588 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
595 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
597 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
598 if let ImportKind::Single { target, .. } = import.kind {
599 let dummy_binding = self.dummy_binding;
600 let dummy_binding = self.import(dummy_binding, import);
601 self.per_ns(|this, ns| {
602 let key = this.new_key(target, ns);
603 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
604 // Consider erroneous imports used to avoid duplicate diagnostics.
605 this.record_use(target, ns, dummy_binding, false);
611 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
612 /// import errors within the same use tree into a single diagnostic.
613 #[derive(Debug, Clone)]
614 struct UnresolvedImportError {
616 label: Option<String>,
618 suggestion: Option<Suggestion>,
621 pub struct ImportResolver<'a, 'b> {
622 pub r: &'a mut Resolver<'b>,
625 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
626 fn parent(self, id: DefId) -> Option<DefId> {
631 impl<'a, 'b> ImportResolver<'a, 'b> {
634 // This is a fixed-point algorithm. We resolve imports until our efforts
635 // are stymied by an unresolved import; then we bail out of the current
636 // module and continue. We terminate successfully once no more imports
637 // remain or unsuccessfully when no forward progress in resolving imports
640 /// Resolves all imports for the crate. This method performs the fixed-
642 pub fn resolve_imports(&mut self) {
643 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
644 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
645 prev_num_indeterminates = self.r.indeterminate_imports.len();
646 for import in mem::take(&mut self.r.indeterminate_imports) {
647 match self.resolve_import(&import) {
648 true => self.r.determined_imports.push(import),
649 false => self.r.indeterminate_imports.push(import),
655 pub fn finalize_imports(&mut self) {
656 for module in self.r.arenas.local_modules().iter() {
657 self.finalize_resolutions_in(module);
660 let mut seen_spans = FxHashSet::default();
661 let mut errors = vec![];
662 let mut prev_root_id: NodeId = NodeId::from_u32(0);
663 let determined_imports = mem::take(&mut self.r.determined_imports);
664 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
666 for (is_indeterminate, import) in determined_imports
669 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
671 if let Some(err) = self.finalize_import(import) {
672 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
673 if source.name == kw::SelfLower {
674 // Silence `unresolved import` error if E0429 is already emitted
675 if let Err(Determined) = source_bindings.value_ns.get() {
681 // If the error is a single failed import then create a "fake" import
682 // resolution for it so that later resolve stages won't complain.
683 self.r.import_dummy_binding(import);
684 if prev_root_id.as_u32() != 0
685 && prev_root_id.as_u32() != import.root_id.as_u32()
686 && !errors.is_empty()
688 // In the case of a new import line, throw a diagnostic message
689 // for the previous line.
690 self.throw_unresolved_import_error(errors, None);
693 if seen_spans.insert(err.span) {
694 let path = import_path_to_string(
695 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
699 errors.push((path, err));
700 prev_root_id = import.root_id;
702 } else if is_indeterminate {
703 // Consider erroneous imports used to avoid duplicate diagnostics.
704 self.r.used_imports.insert((import.id, TypeNS));
705 let path = import_path_to_string(
706 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
710 let err = UnresolvedImportError {
716 errors.push((path, err));
720 if !errors.is_empty() {
721 self.throw_unresolved_import_error(errors, None);
725 fn throw_unresolved_import_error(
727 errors: Vec<(String, UnresolvedImportError)>,
728 span: Option<MultiSpan>,
730 /// Upper limit on the number of `span_label` messages.
731 const MAX_LABEL_COUNT: usize = 10;
733 let (span, msg) = if errors.is_empty() {
734 (span.unwrap(), "unresolved import".to_string())
736 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
738 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
740 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
745 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
747 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
748 for message in note {
753 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
754 if let Some(label) = err.label {
755 diag.span_label(err.span, label);
758 if let Some((suggestions, msg, applicability)) = err.suggestion {
759 diag.multipart_suggestion(&msg, suggestions, applicability);
766 /// Attempts to resolve the given import, returning true if its resolution is determined.
767 /// If successful, the resolved bindings are written into the module.
768 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
770 "(resolving import for module) resolving import `{}::...` in `{}`",
771 Segment::names_to_string(&import.module_path),
772 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
775 let module = if let Some(module) = import.imported_module.get() {
778 // For better failure detection, pretend that the import will
779 // not define any names while resolving its module path.
780 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
781 let path_res = self.r.resolve_path(
784 &import.parent_scope,
789 import.vis.set(orig_vis);
792 PathResult::Module(module) => module,
793 PathResult::Indeterminate => return false,
794 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
798 import.imported_module.set(Some(module));
799 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
807 } => (source, target, source_bindings, target_bindings, type_ns_only),
808 ImportKind::Glob { .. } => {
809 self.resolve_glob_import(import);
815 let mut indeterminate = false;
816 self.r.per_ns(|this, ns| {
817 if !type_ns_only || ns == TypeNS {
818 if let Err(Undetermined) = source_bindings[ns].get() {
819 // For better failure detection, pretend that the import will
820 // not define any names while resolving its module path.
821 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
822 let binding = this.resolve_ident_in_module(
826 &import.parent_scope,
830 import.vis.set(orig_vis);
832 source_bindings[ns].set(binding);
837 let parent = import.parent_scope.module;
838 match source_bindings[ns].get() {
839 Err(Undetermined) => indeterminate = true,
840 // Don't update the resolution, because it was never added.
841 Err(Determined) if target.name == kw::Underscore => {}
843 let key = this.new_key(target, ns);
844 this.update_resolution(parent, key, |_, resolution| {
845 resolution.single_imports.remove(&PtrKey(import));
848 Ok(binding) if !binding.is_importable() => {
849 let msg = format!("`{}` is not directly importable", target);
850 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
851 .span_label(import.span, "cannot be imported directly")
853 // Do not import this illegal binding. Import a dummy binding and pretend
854 // everything is fine
855 this.import_dummy_binding(import);
858 let imported_binding = this.import(binding, import);
859 target_bindings[ns].set(Some(imported_binding));
860 this.define(parent, target, ns, imported_binding);
869 /// Performs final import resolution, consistency checks and error reporting.
871 /// Optionally returns an unresolved import error. This error is buffered and used to
872 /// consolidate multiple unresolved import errors into a single diagnostic.
873 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
874 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
875 let orig_unusable_binding = match &import.kind {
876 ImportKind::Single { target_bindings, .. } => {
877 Some(mem::replace(&mut self.r.unusable_binding, target_bindings[TypeNS].get()))
881 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
882 let path_res = self.r.resolve_path(
885 &import.parent_scope,
890 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
891 if let Some(orig_unusable_binding) = orig_unusable_binding {
892 self.r.unusable_binding = orig_unusable_binding;
894 import.vis.set(orig_vis);
895 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
896 // Consider erroneous imports used to avoid duplicate diagnostics.
897 self.r.used_imports.insert((import.id, TypeNS));
899 let module = match path_res {
900 PathResult::Module(module) => {
901 // Consistency checks, analogous to `finalize_macro_resolutions`.
902 if let Some(initial_module) = import.imported_module.get() {
903 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
904 span_bug!(import.span, "inconsistent resolution for an import");
906 } else if self.r.privacy_errors.is_empty() {
907 let msg = "cannot determine resolution for the import";
908 let msg_note = "import resolution is stuck, try simplifying other imports";
909 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
914 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
916 assert!(import.imported_module.get().is_none());
918 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
922 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
924 assert!(import.imported_module.get().is_none());
925 let err = match self.make_path_suggestion(
927 import.module_path.clone(),
928 &import.parent_scope,
930 Some((suggestion, note)) => UnresolvedImportError {
935 vec![(span, Segment::names_to_string(&suggestion))],
936 String::from("a similar path exists"),
937 Applicability::MaybeIncorrect,
940 None => UnresolvedImportError {
951 PathResult::NonModule(path_res) if path_res.base_res() == Res::Err => {
953 assert!(import.imported_module.get().is_none());
955 // The error was already reported earlier.
958 PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(),
961 let (ident, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
969 } => (source, target, source_bindings, target_bindings, type_ns_only),
970 ImportKind::Glob { is_prelude, ref max_vis } => {
971 if import.module_path.len() <= 1 {
972 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
973 // 2 segments, so the `resolve_path` above won't trigger it.
974 let mut full_path = import.module_path.clone();
975 full_path.push(Segment::from_ident(Ident::invalid()));
976 self.r.lint_if_path_starts_with_module(
984 if let ModuleOrUniformRoot::Module(module) = module {
985 if module.def_id() == import.parent_scope.module.def_id() {
986 // Importing a module into itself is not allowed.
987 return Some(UnresolvedImportError {
989 label: Some(String::from("cannot glob-import a module into itself")),
996 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
997 !max_vis.get().is_at_least(import.vis.get(), &*self)
999 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1000 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
1004 _ => unreachable!(),
1007 let mut all_ns_err = true;
1008 self.r.per_ns(|this, ns| {
1009 if !type_ns_only || ns == TypeNS {
1010 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
1011 let orig_unusable_binding =
1012 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1013 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1014 let binding = this.resolve_ident_in_module(
1018 &import.parent_scope,
1022 this.last_import_segment = orig_last_import_segment;
1023 this.unusable_binding = orig_unusable_binding;
1024 import.vis.set(orig_vis);
1028 // Consistency checks, analogous to `finalize_macro_resolutions`.
1029 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1031 if let Some(target_binding) = target_bindings[ns].get() {
1032 if target.name == kw::Underscore
1033 && initial_binding.is_extern_crate()
1034 && !initial_binding.is_import()
1040 import.module_path.is_empty(),
1044 initial_binding.res()
1046 let res = binding.res();
1047 if let Ok(initial_res) = initial_res {
1048 if res != initial_res && this.ambiguity_errors.is_empty() {
1049 span_bug!(import.span, "inconsistent resolution for an import");
1051 } else if res != Res::Err
1052 && this.ambiguity_errors.is_empty()
1053 && this.privacy_errors.is_empty()
1055 let msg = "cannot determine resolution for the import";
1057 "import resolution is stuck, try simplifying other imports";
1058 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
1062 // FIXME: This assert may fire if public glob is later shadowed by a private
1063 // single import (see test `issue-55884-2.rs`). In theory single imports should
1064 // always block globs, even if they are not yet resolved, so that this kind of
1065 // self-inconsistent resolution never happens.
1066 // Re-enable the assert when the issue is fixed.
1067 // assert!(result[ns].get().is_err());
1074 let mut all_ns_failed = true;
1075 self.r.per_ns(|this, ns| {
1076 if !type_ns_only || ns == TypeNS {
1077 let binding = this.resolve_ident_in_module(
1081 &import.parent_scope,
1085 if binding.is_ok() {
1086 all_ns_failed = false;
1091 return if all_ns_failed {
1092 let resolutions = match module {
1093 ModuleOrUniformRoot::Module(module) => {
1094 Some(self.r.resolutions(module).borrow())
1098 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1099 let names = resolutions
1100 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1103 } // Never suggest the same name
1104 match *resolution.borrow() {
1105 NameResolution { binding: Some(name_binding), .. } => {
1106 match name_binding.kind {
1107 NameBindingKind::Import { binding, .. } => {
1108 match binding.kind {
1109 // Never suggest the name that has binding error
1110 // i.e., the name that cannot be previously resolved
1111 NameBindingKind::Res(Res::Err, _) => None,
1118 NameResolution { ref single_imports, .. }
1119 if single_imports.is_empty() =>
1126 .collect::<Vec<Symbol>>();
1128 let lev_suggestion =
1129 find_best_match_for_name(&names, ident.name, None).map(|suggestion| {
1131 vec![(ident.span, suggestion.to_string())],
1132 String::from("a similar name exists in the module"),
1133 Applicability::MaybeIncorrect,
1137 let (suggestion, note) =
1138 match self.check_for_module_export_macro(import, module, ident) {
1139 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
1140 _ => (lev_suggestion, Vec::new()),
1143 let label = match module {
1144 ModuleOrUniformRoot::Module(module) => {
1145 let module_str = module_to_string(module);
1146 if let Some(module_str) = module_str {
1147 format!("no `{}` in `{}`", ident, module_str)
1149 format!("no `{}` in the root", ident)
1153 if !ident.is_path_segment_keyword() {
1154 format!("no external crate `{}`", ident)
1156 // HACK(eddyb) this shows up for `self` & `super`, which
1157 // should work instead - for now keep the same error message.
1158 format!("no `{}` in the root", ident)
1163 Some(UnresolvedImportError {
1170 // `resolve_ident_in_module` reported a privacy error.
1171 self.r.import_dummy_binding(import);
1176 let mut reexport_error = None;
1177 let mut any_successful_reexport = false;
1178 self.r.per_ns(|this, ns| {
1179 if let Ok(binding) = source_bindings[ns].get() {
1180 let vis = import.vis.get();
1181 if !binding.pseudo_vis().is_at_least(vis, &*this) {
1182 reexport_error = Some((ns, binding));
1184 any_successful_reexport = true;
1189 // All namespaces must be re-exported with extra visibility for an error to occur.
1190 if !any_successful_reexport {
1191 let (ns, binding) = reexport_error.unwrap();
1192 if ns == TypeNS && binding.is_extern_crate() {
1194 "extern crate `{}` is private, and cannot be \
1195 re-exported (error E0365), consider declaring with \
1199 self.r.lint_buffer.buffer_lint(
1200 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1205 } else if ns == TypeNS {
1210 "`{}` is private, and cannot be re-exported",
1213 .span_label(import.span, format!("re-export of private `{}`", ident))
1214 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1217 let msg = format!("`{}` is private, and cannot be re-exported", ident);
1219 format!("consider marking `{}` as `pub` in the imported module", ident,);
1220 struct_span_err!(self.r.session, import.span, E0364, "{}", &msg)
1221 .span_note(import.span, ¬e_msg)
1226 if import.module_path.len() <= 1 {
1227 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1228 // 2 segments, so the `resolve_path` above won't trigger it.
1229 let mut full_path = import.module_path.clone();
1230 full_path.push(Segment::from_ident(ident));
1231 self.r.per_ns(|this, ns| {
1232 if let Ok(binding) = source_bindings[ns].get() {
1233 this.lint_if_path_starts_with_module(
1234 import.crate_lint(),
1243 // Record what this import resolves to for later uses in documentation,
1244 // this may resolve to either a value or a type, but for documentation
1245 // purposes it's good enough to just favor one over the other.
1246 self.r.per_ns(|this, ns| {
1247 if let Ok(binding) = source_bindings[ns].get() {
1248 this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res());
1252 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1254 debug!("(resolving single import) successfully resolved import");
1258 fn check_for_redundant_imports(
1261 import: &'b Import<'b>,
1262 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1263 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1266 // Skip if the import was produced by a macro.
1267 if import.parent_scope.expansion != ExpnId::root() {
1271 // Skip if we are inside a named module (in contrast to an anonymous
1272 // module defined by a block).
1273 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1277 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1279 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1281 self.r.per_ns(|this, ns| {
1282 if let Ok(binding) = source_bindings[ns].get() {
1283 if binding.res() == Res::Err {
1287 let orig_unusable_binding =
1288 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1290 match this.early_resolve_ident_in_lexical_scope(
1292 ScopeSet::All(ns, false),
1293 &import.parent_scope,
1298 Ok(other_binding) => {
1299 is_redundant[ns] = Some(
1300 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1302 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1304 Err(_) => is_redundant[ns] = Some(false),
1307 this.unusable_binding = orig_unusable_binding;
1311 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1313 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1314 redundant_spans.sort();
1315 redundant_spans.dedup();
1316 self.r.lint_buffer.buffer_lint_with_diagnostic(
1320 &format!("the item `{}` is imported redundantly", ident),
1321 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1326 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1327 let module = match import.imported_module.get().unwrap() {
1328 ModuleOrUniformRoot::Module(module) => module,
1330 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1335 if module.is_trait() {
1336 self.r.session.span_err(import.span, "items in traits are not importable.");
1338 } else if module.def_id() == import.parent_scope.module.def_id() {
1340 } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind {
1341 self.r.prelude = Some(module);
1345 // Add to module's glob_importers
1346 module.glob_importers.borrow_mut().push(import);
1348 // Ensure that `resolutions` isn't borrowed during `try_define`,
1349 // since it might get updated via a glob cycle.
1352 .resolutions(module)
1355 .filter_map(|(key, resolution)| {
1356 resolution.borrow().binding().map(|binding| (*key, binding))
1358 .collect::<Vec<_>>();
1359 for (mut key, binding) in bindings {
1360 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1361 Some(Some(def)) => self.r.macro_def_scope(def),
1362 Some(None) => import.parent_scope.module,
1365 if self.r.is_accessible_from(binding.pseudo_vis(), scope) {
1366 let imported_binding = self.r.import(binding, import);
1367 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1371 // Record the destination of this import
1372 self.r.record_partial_res(import.id, PartialRes::new(module.res().unwrap()));
1375 // Miscellaneous post-processing, including recording re-exports,
1376 // reporting conflicts, and reporting unresolved imports.
1377 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1378 // Since import resolution is finished, globs will not define any more names.
1379 *module.globs.borrow_mut() = Vec::new();
1381 let mut reexports = Vec::new();
1383 module.for_each_child(self.r, |this, ident, ns, binding| {
1384 // Filter away ambiguous imports and anything that has def-site
1386 // FIXME: Implement actual cross-crate hygiene.
1387 let is_good_import =
1388 binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
1389 if is_good_import || binding.is_macro_def() {
1390 let res = binding.res().map_id(|id| this.local_def_id(id));
1391 if res != def::Res::Err {
1392 reexports.push(Export { ident, res, span: binding.span, vis: binding.vis });
1396 if let NameBindingKind::Import { binding: orig_binding, import, .. } = binding.kind {
1398 && orig_binding.is_variant()
1399 && !orig_binding.vis.is_at_least(binding.vis, &*this)
1401 let msg = match import.kind {
1402 ImportKind::Single { .. } => {
1403 format!("variant `{}` is private and cannot be re-exported", ident)
1405 ImportKind::Glob { .. } => {
1406 let msg = "enum is private and its variants \
1407 cannot be re-exported"
1410 DiagnosticMessageId::ErrorId(0), // no code?!
1415 this.session.one_time_diagnostics.borrow_mut().insert(error_id);
1421 ref s => bug!("unexpected import kind {:?}", s),
1423 let mut err = this.session.struct_span_err(binding.span, &msg);
1425 let imported_module = match import.imported_module.get() {
1426 Some(ModuleOrUniformRoot::Module(module)) => module,
1427 _ => bug!("module should exist"),
1429 let parent_module = imported_module.parent.expect("parent should exist");
1430 let resolutions = this.resolutions(parent_module).borrow();
1431 let enum_path_segment_index = import.module_path.len() - 1;
1432 let enum_ident = import.module_path[enum_path_segment_index].ident;
1434 let key = this.new_key(enum_ident, TypeNS);
1435 let enum_resolution = resolutions.get(&key).expect("resolution should exist");
1437 enum_resolution.borrow().binding.expect("binding should exist").span;
1438 let enum_def_span = this.session.source_map().guess_head_span(enum_span);
1439 let enum_def_snippet = this
1442 .span_to_snippet(enum_def_span)
1443 .expect("snippet should exist");
1444 // potentially need to strip extant `crate`/`pub(path)` for suggestion
1445 let after_vis_index = enum_def_snippet
1447 .expect("`enum` keyword should exist in snippet");
1448 let suggestion = format!("pub {}", &enum_def_snippet[after_vis_index..]);
1450 this.session.diag_span_suggestion_once(
1452 DiagnosticMessageId::ErrorId(0),
1454 "consider making the enum public",
1462 if !reexports.is_empty() {
1463 if let Some(def_id) = module.def_id() {
1464 // Call to `expect_local` should be fine because current
1465 // code is only called for local modules.
1466 self.r.export_map.insert(def_id.expect_local(), reexports);
1472 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1473 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1474 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1475 if let Some(pos) = pos {
1476 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1477 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1479 let names = if global { &names[1..] } else { names };
1480 if names.is_empty() {
1481 import_kind_to_string(import_kind)
1485 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1486 import_kind_to_string(import_kind),
1492 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1494 ImportKind::Single { source, .. } => source.to_string(),
1495 ImportKind::Glob { .. } => "*".to_string(),
1496 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1497 ImportKind::MacroUse => "#[macro_use]".to_string(),