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::ast::NodeId;
13 use rustc_ast::unwrap_or;
14 use rustc_ast::util::lev_distance::find_best_match_for_name;
15 use rustc_ast_lowering::ResolverAstLowering;
16 use rustc_data_structures::fx::FxHashSet;
17 use rustc_data_structures::ptr_key::PtrKey;
18 use rustc_errors::{pluralize, struct_span_err, Applicability};
19 use rustc_hir::def::{self, PartialRes};
20 use rustc_hir::def_id::DefId;
21 use rustc_middle::hir::exports::Export;
23 use rustc_middle::{bug, span_bug};
24 use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
25 use rustc_session::lint::BuiltinLintDiagnostics;
26 use rustc_session::DiagnosticMessageId;
27 use rustc_span::hygiene::ExpnId;
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 {
118 ImportKind::Glob { .. } => true,
123 pub fn is_nested(&self) -> bool {
125 ImportKind::Single { nested, .. } => nested,
130 crate fn crate_lint(&self) -> CrateLint {
131 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
135 #[derive(Clone, Default, Debug)]
136 /// Records information about the resolution of a name in a namespace of a module.
137 pub struct NameResolution<'a> {
138 /// Single imports that may define the name in the namespace.
139 /// Imports are arena-allocated, so it's ok to use pointers as keys.
140 single_imports: FxHashSet<PtrKey<'a, Import<'a>>>,
141 /// The least shadowable known binding for this name, or None if there are no known bindings.
142 pub binding: Option<&'a NameBinding<'a>>,
143 shadowed_glob: Option<&'a NameBinding<'a>>,
146 impl<'a> NameResolution<'a> {
147 // Returns the binding for the name if it is known or None if it not known.
148 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
149 self.binding.and_then(|binding| {
150 if !binding.is_glob_import() || self.single_imports.is_empty() {
158 crate fn add_single_import(&mut self, import: &'a Import<'a>) {
159 self.single_imports.insert(PtrKey(import));
163 impl<'a> Resolver<'a> {
164 crate fn resolve_ident_in_module_unadjusted(
166 module: ModuleOrUniformRoot<'a>,
169 parent_scope: &ParentScope<'a>,
172 ) -> Result<&'a NameBinding<'a>, Determinacy> {
173 self.resolve_ident_in_module_unadjusted_ext(
182 .map_err(|(determinacy, _)| determinacy)
185 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
186 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
187 crate fn resolve_ident_in_module_unadjusted_ext(
189 module: ModuleOrUniformRoot<'a>,
192 parent_scope: &ParentScope<'a>,
193 restricted_shadowing: bool,
196 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
197 let module = match module {
198 ModuleOrUniformRoot::Module(module) => module,
199 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
200 assert!(!restricted_shadowing);
201 let binding = self.early_resolve_ident_in_lexical_scope(
203 ScopeSet::AbsolutePath(ns),
209 return binding.map_err(|determinacy| (determinacy, Weak::No));
211 ModuleOrUniformRoot::ExternPrelude => {
212 assert!(!restricted_shadowing);
213 return if ns != TypeNS {
214 Err((Determined, Weak::No))
215 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
217 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
218 // Macro-expanded `extern crate` items can add names to extern prelude.
219 Err((Undetermined, Weak::No))
221 Err((Determined, Weak::No))
224 ModuleOrUniformRoot::CurrentScope => {
225 assert!(!restricted_shadowing);
227 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
228 let module = self.resolve_crate_root(ident);
229 let binding = (module, ty::Visibility::Public, module.span, ExpnId::root())
230 .to_name_binding(self.arenas);
232 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
233 // FIXME: Implement these with renaming requirements so that e.g.
234 // `use super;` doesn't work, but `use super as name;` does.
235 // Fall through here to get an error from `early_resolve_...`.
239 let scopes = ScopeSet::All(ns, true);
240 let binding = self.early_resolve_ident_in_lexical_scope(
248 return binding.map_err(|determinacy| (determinacy, Weak::No));
252 let key = self.new_key(ident, ns);
254 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
256 if let Some(binding) = resolution.binding {
257 if !restricted_shadowing && binding.expansion != ExpnId::root() {
258 if let NameBindingKind::Res(_, true) = binding.kind {
259 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
264 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
265 if let Some(unusable_binding) = this.unusable_binding {
266 if ptr::eq(binding, unusable_binding) {
267 return Err((Determined, Weak::No));
270 // `extern crate` are always usable for backwards compatibility, see issue #37020,
271 // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`.
272 let usable = this.is_accessible_from(binding.vis, parent_scope.module)
273 || binding.is_extern_crate();
274 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
280 .and_then(|binding| {
281 // If the primary binding is unusable, search further and return the shadowed glob
282 // binding if it exists. What we really want here is having two separate scopes in
283 // a module - one for non-globs and one for globs, but until that's done use this
284 // hack to avoid inconsistent resolution ICEs during import validation.
285 if let Some(unusable_binding) = self.unusable_binding {
286 if ptr::eq(binding, unusable_binding) {
287 return resolution.shadowed_glob;
292 .ok_or((Determined, Weak::No))
293 .and_then(|binding| {
294 if self.last_import_segment && check_usable(self, binding).is_err() {
295 Err((Determined, Weak::No))
297 self.record_use(ident, ns, binding, restricted_shadowing);
299 if let Some(shadowed_glob) = resolution.shadowed_glob {
300 // Forbid expanded shadowing to avoid time travel.
301 if restricted_shadowing
302 && binding.expansion != ExpnId::root()
303 && binding.res() != shadowed_glob.res()
305 self.ambiguity_errors.push(AmbiguityError {
306 kind: AmbiguityKind::GlobVsExpanded,
310 misc1: AmbiguityErrorMisc::None,
311 misc2: AmbiguityErrorMisc::None,
316 if !(self.is_accessible_from(binding.vis, parent_scope.module) ||
317 // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
318 (self.last_import_segment && binding.is_extern_crate()))
320 self.privacy_errors.push(PrivacyError {
323 dedup_span: path_span,
332 // Items and single imports are not shadowable, if we have one, then it's determined.
333 if let Some(binding) = resolution.binding {
334 if !binding.is_glob_import() {
335 return check_usable(self, binding);
339 // --- From now on we either have a glob resolution or no resolution. ---
341 // Check if one of single imports can still define the name,
342 // if it can then our result is not determined and can be invalidated.
343 for single_import in &resolution.single_imports {
344 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
347 let module = unwrap_or!(
348 single_import.imported_module.get(),
349 return Err((Undetermined, Weak::No))
351 let ident = match single_import.kind {
352 ImportKind::Single { source, .. } => source,
355 match self.resolve_ident_in_module(
359 &single_import.parent_scope,
363 Err(Determined) => continue,
365 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
369 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
373 // So we have a resolution that's from a glob import. This resolution is determined
374 // if it cannot be shadowed by some new item/import expanded from a macro.
375 // This happens either if there are no unexpanded macros, or expanded names cannot
376 // shadow globs (that happens in macro namespace or with restricted shadowing).
378 // Additionally, any macro in any module can plant names in the root module if it creates
379 // `macro_export` macros, so the root module effectively has unresolved invocations if any
380 // module has unresolved invocations.
381 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
382 // progress, we have to ignore those potential unresolved invocations from other modules
383 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
384 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
385 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
386 if let Some(binding) = resolution.binding {
387 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
388 return check_usable(self, binding);
390 return Err((Undetermined, Weak::No));
394 // --- From now on we have no resolution. ---
396 // Now we are in situation when new item/import can appear only from a glob or a macro
397 // expansion. With restricted shadowing names from globs and macro expansions cannot
398 // shadow names from outer scopes, so we can freely fallback from module search to search
399 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
400 // scopes we return `Undetermined` with `Weak::Yes`.
402 // Check if one of unexpanded macros can still define the name,
403 // if it can then our "no resolution" result is not determined and can be invalidated.
404 if unexpanded_macros {
405 return Err((Undetermined, Weak::Yes));
408 // Check if one of glob imports can still define the name,
409 // if it can then our "no resolution" result is not determined and can be invalidated.
410 for glob_import in module.globs.borrow().iter() {
411 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
414 let module = match glob_import.imported_module.get() {
415 Some(ModuleOrUniformRoot::Module(module)) => module,
417 None => return Err((Undetermined, Weak::Yes)),
419 let tmp_parent_scope;
420 let (mut adjusted_parent_scope, mut ident) =
421 (parent_scope, ident.normalize_to_macros_2_0());
422 match ident.span.glob_adjust(module.expansion, glob_import.span) {
425 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
426 adjusted_parent_scope = &tmp_parent_scope;
431 let result = self.resolve_ident_in_module_unadjusted(
432 ModuleOrUniformRoot::Module(module),
435 adjusted_parent_scope,
441 Err(Determined) => continue,
443 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
447 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
451 // No resolution and no one else can define the name - determinate error.
452 Err((Determined, Weak::No))
455 // Given a binding and an import that resolves to it,
456 // return the corresponding binding defined by the import.
459 binding: &'a NameBinding<'a>,
460 import: &'a Import<'a>,
461 ) -> &'a NameBinding<'a> {
462 let vis = if binding.pseudo_vis().is_at_least(import.vis.get(), self) ||
463 // cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
464 !import.is_glob() && binding.is_extern_crate()
471 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
472 if vis == import.vis.get() || vis.is_at_least(max_vis.get(), self) {
477 self.arenas.alloc_name_binding(NameBinding {
478 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
482 expansion: import.parent_scope.expansion,
486 // Define the name or return the existing binding if there is a collision.
491 binding: &'a NameBinding<'a>,
492 ) -> Result<(), &'a NameBinding<'a>> {
493 let res = binding.res();
494 self.check_reserved_macro_name(key.ident, res);
495 self.set_binding_parent_module(binding, module);
496 self.update_resolution(module, key, |this, resolution| {
497 if let Some(old_binding) = resolution.binding {
499 // Do not override real bindings with `Res::Err`s from error recovery.
502 match (old_binding.is_glob_import(), binding.is_glob_import()) {
504 if res != old_binding.res() {
505 resolution.binding = Some(this.ambiguity(
506 AmbiguityKind::GlobVsGlob,
510 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
511 // We are glob-importing the same item but with greater visibility.
512 resolution.binding = Some(binding);
515 (old_glob @ true, false) | (old_glob @ false, true) => {
516 let (glob_binding, nonglob_binding) =
517 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
518 if glob_binding.res() != nonglob_binding.res()
520 && nonglob_binding.expansion != ExpnId::root()
522 resolution.binding = Some(this.ambiguity(
523 AmbiguityKind::GlobVsExpanded,
528 resolution.binding = Some(nonglob_binding);
530 resolution.shadowed_glob = Some(glob_binding);
533 return Err(old_binding);
537 resolution.binding = Some(binding);
547 primary_binding: &'a NameBinding<'a>,
548 secondary_binding: &'a NameBinding<'a>,
549 ) -> &'a NameBinding<'a> {
550 self.arenas.alloc_name_binding(NameBinding {
551 ambiguity: Some((secondary_binding, kind)),
552 ..primary_binding.clone()
556 // Use `f` to mutate the resolution of the name in the module.
557 // If the resolution becomes a success, define it in the module's glob importers.
558 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
560 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
562 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
563 // during which the resolution might end up getting re-defined via a glob cycle.
565 let resolution = &mut *self.resolution(module, key).borrow_mut();
566 let old_binding = resolution.binding();
568 let t = f(self, resolution);
570 match resolution.binding() {
571 _ if old_binding.is_some() => return t,
573 Some(binding) => match old_binding {
574 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
580 // Define `binding` in `module`s glob importers.
581 for import in module.glob_importers.borrow_mut().iter() {
582 let mut ident = key.ident;
583 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
584 Some(Some(def)) => self.macro_def_scope(def),
585 Some(None) => import.parent_scope.module,
588 if self.is_accessible_from(binding.vis, scope) {
589 let imported_binding = self.import(binding, import);
590 let key = BindingKey { ident, ..key };
591 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
598 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
600 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
601 if let ImportKind::Single { target, .. } = import.kind {
602 let dummy_binding = self.dummy_binding;
603 let dummy_binding = self.import(dummy_binding, import);
604 self.per_ns(|this, ns| {
605 let key = this.new_key(target, ns);
606 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
607 // Consider erroneous imports used to avoid duplicate diagnostics.
608 this.record_use(target, ns, dummy_binding, false);
614 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
615 /// import errors within the same use tree into a single diagnostic.
616 #[derive(Debug, Clone)]
617 struct UnresolvedImportError {
619 label: Option<String>,
621 suggestion: Option<Suggestion>,
624 pub struct ImportResolver<'a, 'b> {
625 pub r: &'a mut Resolver<'b>,
628 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
629 fn parent(self, id: DefId) -> Option<DefId> {
634 impl<'a, 'b> ImportResolver<'a, 'b> {
637 // This is a fixed-point algorithm. We resolve imports until our efforts
638 // are stymied by an unresolved import; then we bail out of the current
639 // module and continue. We terminate successfully once no more imports
640 // remain or unsuccessfully when no forward progress in resolving imports
643 /// Resolves all imports for the crate. This method performs the fixed-
645 pub fn resolve_imports(&mut self) {
646 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
647 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
648 prev_num_indeterminates = self.r.indeterminate_imports.len();
649 for import in mem::take(&mut self.r.indeterminate_imports) {
650 match self.resolve_import(&import) {
651 true => self.r.determined_imports.push(import),
652 false => self.r.indeterminate_imports.push(import),
658 pub fn finalize_imports(&mut self) {
659 for module in self.r.arenas.local_modules().iter() {
660 self.finalize_resolutions_in(module);
663 let mut seen_spans = FxHashSet::default();
664 let mut errors = vec![];
665 let mut prev_root_id: NodeId = NodeId::from_u32(0);
666 let determined_imports = mem::take(&mut self.r.determined_imports);
667 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
669 for (is_indeterminate, import) in determined_imports
672 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
674 if let Some(err) = self.finalize_import(import) {
675 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
676 if source.name == kw::SelfLower {
677 // Silence `unresolved import` error if E0429 is already emitted
678 if let Err(Determined) = source_bindings.value_ns.get() {
684 // If the error is a single failed import then create a "fake" import
685 // resolution for it so that later resolve stages won't complain.
686 self.r.import_dummy_binding(import);
687 if prev_root_id.as_u32() != 0
688 && prev_root_id.as_u32() != import.root_id.as_u32()
689 && !errors.is_empty()
691 // In the case of a new import line, throw a diagnostic message
692 // for the previous line.
693 self.throw_unresolved_import_error(errors, None);
696 if seen_spans.insert(err.span) {
697 let path = import_path_to_string(
698 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
702 errors.push((path, err));
703 prev_root_id = import.root_id;
705 } else if is_indeterminate {
706 // Consider erroneous imports used to avoid duplicate diagnostics.
707 self.r.used_imports.insert((import.id, TypeNS));
708 let path = import_path_to_string(
709 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
713 let err = UnresolvedImportError {
719 errors.push((path, err));
723 if !errors.is_empty() {
724 self.throw_unresolved_import_error(errors, None);
728 fn throw_unresolved_import_error(
730 errors: Vec<(String, UnresolvedImportError)>,
731 span: Option<MultiSpan>,
733 /// Upper limit on the number of `span_label` messages.
734 const MAX_LABEL_COUNT: usize = 10;
736 let (span, msg) = if errors.is_empty() {
737 (span.unwrap(), "unresolved import".to_string())
739 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
741 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
743 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
748 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
750 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
751 for message in note {
756 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
757 if let Some(label) = err.label {
758 diag.span_label(err.span, label);
761 if let Some((suggestions, msg, applicability)) = err.suggestion {
762 diag.multipart_suggestion(&msg, suggestions, applicability);
769 /// Attempts to resolve the given import, returning true if its resolution is determined.
770 /// If successful, the resolved bindings are written into the module.
771 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
773 "(resolving import for module) resolving import `{}::...` in `{}`",
774 Segment::names_to_string(&import.module_path),
775 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
778 let module = if let Some(module) = import.imported_module.get() {
781 // For better failure detection, pretend that the import will
782 // not define any names while resolving its module path.
783 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
784 let path_res = self.r.resolve_path(
787 &import.parent_scope,
792 import.vis.set(orig_vis);
795 PathResult::Module(module) => module,
796 PathResult::Indeterminate => return false,
797 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
801 import.imported_module.set(Some(module));
802 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
810 } => (source, target, source_bindings, target_bindings, type_ns_only),
811 ImportKind::Glob { .. } => {
812 self.resolve_glob_import(import);
818 let mut indeterminate = false;
819 self.r.per_ns(|this, ns| {
820 if !type_ns_only || ns == TypeNS {
821 if let Err(Undetermined) = source_bindings[ns].get() {
822 // For better failure detection, pretend that the import will
823 // not define any names while resolving its module path.
824 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
825 let binding = this.resolve_ident_in_module(
829 &import.parent_scope,
833 import.vis.set(orig_vis);
835 source_bindings[ns].set(binding);
840 let parent = import.parent_scope.module;
841 match source_bindings[ns].get() {
842 Err(Undetermined) => indeterminate = true,
843 // Don't update the resolution, because it was never added.
844 Err(Determined) if target.name == kw::Underscore => {}
846 let key = this.new_key(target, ns);
847 this.update_resolution(parent, key, |_, resolution| {
848 resolution.single_imports.remove(&PtrKey(import));
851 Ok(binding) if !binding.is_importable() => {
852 let msg = format!("`{}` is not directly importable", target);
853 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
854 .span_label(import.span, "cannot be imported directly")
856 // Do not import this illegal binding. Import a dummy binding and pretend
857 // everything is fine
858 this.import_dummy_binding(import);
861 let imported_binding = this.import(binding, import);
862 target_bindings[ns].set(Some(imported_binding));
863 this.define(parent, target, ns, imported_binding);
872 /// Performs final import resolution, consistency checks and error reporting.
874 /// Optionally returns an unresolved import error. This error is buffered and used to
875 /// consolidate multiple unresolved import errors into a single diagnostic.
876 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
877 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
878 let orig_unusable_binding = match &import.kind {
879 ImportKind::Single { target_bindings, .. } => {
880 Some(mem::replace(&mut self.r.unusable_binding, target_bindings[TypeNS].get()))
884 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
885 let path_res = self.r.resolve_path(
888 &import.parent_scope,
893 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
894 if let Some(orig_unusable_binding) = orig_unusable_binding {
895 self.r.unusable_binding = orig_unusable_binding;
897 import.vis.set(orig_vis);
898 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
899 // Consider erroneous imports used to avoid duplicate diagnostics.
900 self.r.used_imports.insert((import.id, TypeNS));
902 let module = match path_res {
903 PathResult::Module(module) => {
904 // Consistency checks, analogous to `finalize_macro_resolutions`.
905 if let Some(initial_module) = import.imported_module.get() {
906 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
907 span_bug!(import.span, "inconsistent resolution for an import");
910 if self.r.privacy_errors.is_empty() {
911 let msg = "cannot determine resolution for the import";
912 let msg_note = "import resolution is stuck, try simplifying other imports";
913 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
919 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
921 assert!(import.imported_module.get().is_none());
923 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
927 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
929 assert!(import.imported_module.get().is_none());
930 let err = match self.make_path_suggestion(
932 import.module_path.clone(),
933 &import.parent_scope,
935 Some((suggestion, note)) => UnresolvedImportError {
940 vec![(span, Segment::names_to_string(&suggestion))],
941 String::from("a similar path exists"),
942 Applicability::MaybeIncorrect,
945 None => UnresolvedImportError {
956 PathResult::NonModule(path_res) if path_res.base_res() == Res::Err => {
958 assert!(import.imported_module.get().is_none());
960 // The error was already reported earlier.
963 PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(),
966 let (ident, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
974 } => (source, target, source_bindings, target_bindings, type_ns_only),
975 ImportKind::Glob { is_prelude, ref max_vis } => {
976 if import.module_path.len() <= 1 {
977 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
978 // 2 segments, so the `resolve_path` above won't trigger it.
979 let mut full_path = import.module_path.clone();
980 full_path.push(Segment::from_ident(Ident::invalid()));
981 self.r.lint_if_path_starts_with_module(
989 if let ModuleOrUniformRoot::Module(module) = module {
990 if module.def_id() == import.parent_scope.module.def_id() {
991 // Importing a module into itself is not allowed.
992 return Some(UnresolvedImportError {
994 label: Some(String::from("cannot glob-import a module into itself")),
1001 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
1002 !max_vis.get().is_at_least(import.vis.get(), &*self)
1004 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1005 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
1009 _ => unreachable!(),
1012 let mut all_ns_err = true;
1013 self.r.per_ns(|this, ns| {
1014 if !type_ns_only || ns == TypeNS {
1015 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
1016 let orig_unusable_binding =
1017 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1018 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1019 let binding = this.resolve_ident_in_module(
1023 &import.parent_scope,
1027 this.last_import_segment = orig_last_import_segment;
1028 this.unusable_binding = orig_unusable_binding;
1029 import.vis.set(orig_vis);
1033 // Consistency checks, analogous to `finalize_macro_resolutions`.
1034 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1036 if let Some(target_binding) = target_bindings[ns].get() {
1037 if target.name == kw::Underscore
1038 && initial_binding.is_extern_crate()
1039 && !initial_binding.is_import()
1045 import.module_path.is_empty(),
1049 initial_binding.res()
1051 let res = binding.res();
1052 if let Ok(initial_res) = initial_res {
1053 if res != initial_res && this.ambiguity_errors.is_empty() {
1054 span_bug!(import.span, "inconsistent resolution for an import");
1058 && this.ambiguity_errors.is_empty()
1059 && this.privacy_errors.is_empty()
1061 let msg = "cannot determine resolution for the import";
1063 "import resolution is stuck, try simplifying other imports";
1065 .struct_span_err(import.span, msg)
1072 // FIXME: This assert may fire if public glob is later shadowed by a private
1073 // single import (see test `issue-55884-2.rs`). In theory single imports should
1074 // always block globs, even if they are not yet resolved, so that this kind of
1075 // self-inconsistent resolution never happens.
1076 // Re-enable the assert when the issue is fixed.
1077 // assert!(result[ns].get().is_err());
1084 let mut all_ns_failed = true;
1085 self.r.per_ns(|this, ns| {
1086 if !type_ns_only || ns == TypeNS {
1087 let binding = this.resolve_ident_in_module(
1091 &import.parent_scope,
1095 if binding.is_ok() {
1096 all_ns_failed = false;
1101 return if all_ns_failed {
1102 let resolutions = match module {
1103 ModuleOrUniformRoot::Module(module) => {
1104 Some(self.r.resolutions(module).borrow())
1108 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1109 let names = resolutions.filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1112 } // Never suggest the same name
1113 match *resolution.borrow() {
1114 NameResolution { binding: Some(name_binding), .. } => {
1115 match name_binding.kind {
1116 NameBindingKind::Import { binding, .. } => {
1117 match binding.kind {
1118 // Never suggest the name that has binding error
1119 // i.e., the name that cannot be previously resolved
1120 NameBindingKind::Res(Res::Err, _) => None,
1127 NameResolution { ref single_imports, .. } if single_imports.is_empty() => {
1134 let lev_suggestion =
1135 find_best_match_for_name(names, ident.name, None).map(|suggestion| {
1137 vec![(ident.span, suggestion.to_string())],
1138 String::from("a similar name exists in the module"),
1139 Applicability::MaybeIncorrect,
1143 let (suggestion, note) =
1144 match self.check_for_module_export_macro(import, module, ident) {
1145 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
1146 _ => (lev_suggestion, Vec::new()),
1149 let label = match module {
1150 ModuleOrUniformRoot::Module(module) => {
1151 let module_str = module_to_string(module);
1152 if let Some(module_str) = module_str {
1153 format!("no `{}` in `{}`", ident, module_str)
1155 format!("no `{}` in the root", ident)
1159 if !ident.is_path_segment_keyword() {
1160 format!("no `{}` external crate", ident)
1162 // HACK(eddyb) this shows up for `self` & `super`, which
1163 // should work instead - for now keep the same error message.
1164 format!("no `{}` in the root", ident)
1169 Some(UnresolvedImportError {
1176 // `resolve_ident_in_module` reported a privacy error.
1177 self.r.import_dummy_binding(import);
1182 let mut reexport_error = None;
1183 let mut any_successful_reexport = false;
1184 self.r.per_ns(|this, ns| {
1185 if let Ok(binding) = source_bindings[ns].get() {
1186 let vis = import.vis.get();
1187 if !binding.pseudo_vis().is_at_least(vis, &*this) {
1188 reexport_error = Some((ns, binding));
1190 any_successful_reexport = true;
1195 // All namespaces must be re-exported with extra visibility for an error to occur.
1196 if !any_successful_reexport {
1197 let (ns, binding) = reexport_error.unwrap();
1198 if ns == TypeNS && binding.is_extern_crate() {
1200 "extern crate `{}` is private, and cannot be \
1201 re-exported (error E0365), consider declaring with \
1205 self.r.lint_buffer.buffer_lint(
1206 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1211 } else if ns == TypeNS {
1216 "`{}` is private, and cannot be re-exported",
1219 .span_label(import.span, format!("re-export of private `{}`", ident))
1220 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1223 let msg = format!("`{}` is private, and cannot be re-exported", ident);
1225 format!("consider marking `{}` as `pub` in the imported module", ident,);
1226 struct_span_err!(self.r.session, import.span, E0364, "{}", &msg)
1227 .span_note(import.span, ¬e_msg)
1232 if import.module_path.len() <= 1 {
1233 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1234 // 2 segments, so the `resolve_path` above won't trigger it.
1235 let mut full_path = import.module_path.clone();
1236 full_path.push(Segment::from_ident(ident));
1237 self.r.per_ns(|this, ns| {
1238 if let Ok(binding) = source_bindings[ns].get() {
1239 this.lint_if_path_starts_with_module(
1240 import.crate_lint(),
1249 // Record what this import resolves to for later uses in documentation,
1250 // this may resolve to either a value or a type, but for documentation
1251 // purposes it's good enough to just favor one over the other.
1252 self.r.per_ns(|this, ns| {
1253 if let Ok(binding) = source_bindings[ns].get() {
1254 this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res());
1258 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1260 debug!("(resolving single import) successfully resolved import");
1264 fn check_for_redundant_imports(
1267 import: &'b Import<'b>,
1268 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1269 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1272 // Skip if the import was produced by a macro.
1273 if import.parent_scope.expansion != ExpnId::root() {
1277 // Skip if we are inside a named module (in contrast to an anonymous
1278 // module defined by a block).
1279 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1283 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1285 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1287 self.r.per_ns(|this, ns| {
1288 if let Ok(binding) = source_bindings[ns].get() {
1289 if binding.res() == Res::Err {
1293 let orig_unusable_binding =
1294 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1296 match this.early_resolve_ident_in_lexical_scope(
1298 ScopeSet::All(ns, false),
1299 &import.parent_scope,
1304 Ok(other_binding) => {
1305 is_redundant[ns] = Some(
1306 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1308 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1310 Err(_) => is_redundant[ns] = Some(false),
1313 this.unusable_binding = orig_unusable_binding;
1317 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1319 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1320 redundant_spans.sort();
1321 redundant_spans.dedup();
1322 self.r.lint_buffer.buffer_lint_with_diagnostic(
1326 &format!("the item `{}` is imported redundantly", ident),
1327 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1332 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1333 let module = match import.imported_module.get().unwrap() {
1334 ModuleOrUniformRoot::Module(module) => module,
1336 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1341 if module.is_trait() {
1342 self.r.session.span_err(import.span, "items in traits are not importable.");
1344 } else if module.def_id() == import.parent_scope.module.def_id() {
1346 } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind {
1347 self.r.prelude = Some(module);
1351 // Add to module's glob_importers
1352 module.glob_importers.borrow_mut().push(import);
1354 // Ensure that `resolutions` isn't borrowed during `try_define`,
1355 // since it might get updated via a glob cycle.
1358 .resolutions(module)
1361 .filter_map(|(key, resolution)| {
1362 resolution.borrow().binding().map(|binding| (*key, binding))
1364 .collect::<Vec<_>>();
1365 for (mut key, binding) in bindings {
1366 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1367 Some(Some(def)) => self.r.macro_def_scope(def),
1368 Some(None) => import.parent_scope.module,
1371 if self.r.is_accessible_from(binding.pseudo_vis(), scope) {
1372 let imported_binding = self.r.import(binding, import);
1373 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1377 // Record the destination of this import
1378 self.r.record_partial_res(import.id, PartialRes::new(module.res().unwrap()));
1381 // Miscellaneous post-processing, including recording re-exports,
1382 // reporting conflicts, and reporting unresolved imports.
1383 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1384 // Since import resolution is finished, globs will not define any more names.
1385 *module.globs.borrow_mut() = Vec::new();
1387 let mut reexports = Vec::new();
1389 module.for_each_child(self.r, |this, ident, ns, binding| {
1390 // Filter away ambiguous imports and anything that has def-site
1392 // FIXME: Implement actual cross-crate hygiene.
1393 let is_good_import =
1394 binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
1395 if is_good_import || binding.is_macro_def() {
1396 let res = binding.res().map_id(|id| this.local_def_id(id));
1397 if res != def::Res::Err {
1398 reexports.push(Export { ident, res, span: binding.span, vis: binding.vis });
1402 if let NameBindingKind::Import { binding: orig_binding, import, .. } = binding.kind {
1404 && orig_binding.is_variant()
1405 && !orig_binding.vis.is_at_least(binding.vis, &*this)
1407 let msg = match import.kind {
1408 ImportKind::Single { .. } => {
1409 format!("variant `{}` is private and cannot be re-exported", ident)
1411 ImportKind::Glob { .. } => {
1412 let msg = "enum is private and its variants \
1413 cannot be re-exported"
1416 DiagnosticMessageId::ErrorId(0), // no code?!
1421 this.session.one_time_diagnostics.borrow_mut().insert(error_id);
1427 ref s => bug!("unexpected import kind {:?}", s),
1429 let mut err = this.session.struct_span_err(binding.span, &msg);
1431 let imported_module = match import.imported_module.get() {
1432 Some(ModuleOrUniformRoot::Module(module)) => module,
1433 _ => bug!("module should exist"),
1435 let parent_module = imported_module.parent.expect("parent should exist");
1436 let resolutions = this.resolutions(parent_module).borrow();
1437 let enum_path_segment_index = import.module_path.len() - 1;
1438 let enum_ident = import.module_path[enum_path_segment_index].ident;
1440 let key = this.new_key(enum_ident, TypeNS);
1441 let enum_resolution = resolutions.get(&key).expect("resolution should exist");
1443 enum_resolution.borrow().binding.expect("binding should exist").span;
1444 let enum_def_span = this.session.source_map().guess_head_span(enum_span);
1445 let enum_def_snippet = this
1448 .span_to_snippet(enum_def_span)
1449 .expect("snippet should exist");
1450 // potentially need to strip extant `crate`/`pub(path)` for suggestion
1451 let after_vis_index = enum_def_snippet
1453 .expect("`enum` keyword should exist in snippet");
1454 let suggestion = format!("pub {}", &enum_def_snippet[after_vis_index..]);
1456 this.session.diag_span_suggestion_once(
1458 DiagnosticMessageId::ErrorId(0),
1460 "consider making the enum public",
1468 if !reexports.is_empty() {
1469 if let Some(def_id) = module.def_id() {
1470 // Call to `expect_local` should be fine because current
1471 // code is only called for local modules.
1472 self.r.export_map.insert(def_id.expect_local(), reexports);
1478 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1479 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1480 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1481 if let Some(pos) = pos {
1482 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1483 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1485 let names = if global { &names[1..] } else { names };
1486 if names.is_empty() {
1487 import_kind_to_string(import_kind)
1491 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1492 import_kind_to_string(import_kind),
1498 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1500 ImportKind::Single { source, .. } => source.to_string(),
1501 ImportKind::Glob { .. } => "*".to_string(),
1502 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1503 ImportKind::MacroUse => "#[macro_use]".to_string(),