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::NodeId;
13 use rustc_data_structures::fx::FxHashSet;
14 use rustc_data_structures::ptr_key::PtrKey;
15 use rustc_errors::{pluralize, struct_span_err, Applicability};
16 use rustc_hir::def::{self, PartialRes};
17 use rustc_hir::def_id::DefId;
18 use rustc_middle::hir::exports::Export;
19 use rustc_middle::span_bug;
21 use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
22 use rustc_session::lint::BuiltinLintDiagnostics;
23 use rustc_span::hygiene::LocalExpnId;
24 use rustc_span::lev_distance::find_best_match_for_name;
25 use rustc_span::symbol::{kw, Ident, Symbol};
26 use rustc_span::{MultiSpan, Span};
33 type Res = def::Res<NodeId>;
35 /// Contains data for specific kinds of imports.
36 #[derive(Clone, Debug)]
37 pub enum ImportKind<'a> {
39 /// `source` in `use prefix::source as target`.
41 /// `target` in `use prefix::source as target`.
43 /// Bindings to which `source` refers to.
44 source_bindings: PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
45 /// Bindings introduced by `target`.
46 target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>,
47 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
49 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
54 max_vis: Cell<ty::Visibility>, // The visibility of the greatest re-export.
55 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
58 source: Option<Symbol>,
65 #[derive(Debug, Clone)]
66 crate struct Import<'a> {
67 pub kind: ImportKind<'a>,
69 /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`.
71 /// In the case where the `Import` was expanded from a "nested" use tree,
72 /// this id is the ID of the leaf tree. For example:
74 /// ```ignore (pacify the mercilous tidy)
75 /// use foo::bar::{a, b}
78 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
79 /// for `a` in this field.
82 /// The `id` of the "root" use-kind -- this is always the same as
83 /// `id` except in the case of "nested" use trees, in which case
84 /// it will be the `id` of the root use tree. e.g., in the example
85 /// from `id`, this would be the ID of the `use foo::bar`
89 /// Span of the entire use statement.
92 /// Span of the entire use statement with attributes.
93 pub use_span_with_attributes: Span,
95 /// Did the use statement have any attributes?
96 pub has_attributes: bool,
98 /// Span of this use tree.
101 /// Span of the *root* use tree (see `root_id`).
104 pub parent_scope: ParentScope<'a>,
105 pub module_path: Vec<Segment>,
106 /// The resolution of `module_path`.
107 pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>,
108 pub vis: Cell<ty::Visibility>,
109 pub used: Cell<bool>,
112 impl<'a> Import<'a> {
113 pub fn is_glob(&self) -> bool {
114 matches!(self.kind, ImportKind::Glob { .. })
117 pub fn is_nested(&self) -> bool {
119 ImportKind::Single { nested, .. } => nested,
124 crate fn crate_lint(&self) -> CrateLint {
125 CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span }
129 #[derive(Clone, Default, Debug)]
130 /// Records information about the resolution of a name in a namespace of a module.
131 pub struct NameResolution<'a> {
132 /// Single imports that may define the name in the namespace.
133 /// Imports are arena-allocated, so it's ok to use pointers as keys.
134 single_imports: FxHashSet<PtrKey<'a, Import<'a>>>,
135 /// The least shadowable known binding for this name, or None if there are no known bindings.
136 pub binding: Option<&'a NameBinding<'a>>,
137 shadowed_glob: Option<&'a NameBinding<'a>>,
140 impl<'a> NameResolution<'a> {
141 // Returns the binding for the name if it is known or None if it not known.
142 pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> {
143 self.binding.and_then(|binding| {
144 if !binding.is_glob_import() || self.single_imports.is_empty() {
152 crate fn add_single_import(&mut self, import: &'a Import<'a>) {
153 self.single_imports.insert(PtrKey(import));
157 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
158 // are permitted for backward-compatibility under a deprecation lint.
159 fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool {
160 match (&import.kind, &binding.kind) {
162 ImportKind::Single { .. },
163 NameBindingKind::Import {
164 import: Import { kind: ImportKind::ExternCrate { .. }, .. },
167 ) => import.vis.get() == ty::Visibility::Public,
172 impl<'a> Resolver<'a> {
173 crate fn resolve_ident_in_module_unadjusted(
175 module: ModuleOrUniformRoot<'a>,
178 parent_scope: &ParentScope<'a>,
181 ) -> Result<&'a NameBinding<'a>, Determinacy> {
182 self.resolve_ident_in_module_unadjusted_ext(
191 .map_err(|(determinacy, _)| determinacy)
194 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
195 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
196 crate fn resolve_ident_in_module_unadjusted_ext(
198 module: ModuleOrUniformRoot<'a>,
201 parent_scope: &ParentScope<'a>,
202 restricted_shadowing: bool,
205 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
206 let module = match module {
207 ModuleOrUniformRoot::Module(module) => module,
208 ModuleOrUniformRoot::CrateRootAndExternPrelude => {
209 assert!(!restricted_shadowing);
210 let binding = self.early_resolve_ident_in_lexical_scope(
212 ScopeSet::AbsolutePath(ns),
218 return binding.map_err(|determinacy| (determinacy, Weak::No));
220 ModuleOrUniformRoot::ExternPrelude => {
221 assert!(!restricted_shadowing);
222 return if ns != TypeNS {
223 Err((Determined, Weak::No))
224 } else if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
226 } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
227 // Macro-expanded `extern crate` items can add names to extern prelude.
228 Err((Undetermined, Weak::No))
230 Err((Determined, Weak::No))
233 ModuleOrUniformRoot::CurrentScope => {
234 assert!(!restricted_shadowing);
236 if ident.name == kw::Crate || ident.name == kw::DollarCrate {
237 let module = self.resolve_crate_root(ident);
239 (module, ty::Visibility::Public, module.span, LocalExpnId::ROOT)
240 .to_name_binding(self.arenas);
242 } else if ident.name == kw::Super || ident.name == kw::SelfLower {
243 // FIXME: Implement these with renaming requirements so that e.g.
244 // `use super;` doesn't work, but `use super as name;` does.
245 // Fall through here to get an error from `early_resolve_...`.
249 let scopes = ScopeSet::All(ns, true);
250 let binding = self.early_resolve_ident_in_lexical_scope(
258 return binding.map_err(|determinacy| (determinacy, Weak::No));
262 let key = self.new_key(ident, ns);
264 self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
266 if let Some(binding) = resolution.binding {
267 if !restricted_shadowing && binding.expansion != LocalExpnId::ROOT {
268 if let NameBindingKind::Res(_, true) = binding.kind {
269 self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
274 let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| {
275 if let Some(unusable_binding) = this.unusable_binding {
276 if ptr::eq(binding, unusable_binding) {
277 return Err((Determined, Weak::No));
280 let usable = this.is_accessible_from(binding.vis, parent_scope.module);
281 if usable { Ok(binding) } else { Err((Determined, Weak::No)) }
287 .and_then(|binding| {
288 // If the primary binding is unusable, search further and return the shadowed glob
289 // binding if it exists. What we really want here is having two separate scopes in
290 // a module - one for non-globs and one for globs, but until that's done use this
291 // hack to avoid inconsistent resolution ICEs during import validation.
292 if let Some(unusable_binding) = self.unusable_binding {
293 if ptr::eq(binding, unusable_binding) {
294 return resolution.shadowed_glob;
299 .ok_or((Determined, Weak::No))
300 .and_then(|binding| {
301 if self.last_import_segment && check_usable(self, binding).is_err() {
302 Err((Determined, Weak::No))
304 self.record_use(ident, binding, restricted_shadowing);
306 if let Some(shadowed_glob) = resolution.shadowed_glob {
307 // Forbid expanded shadowing to avoid time travel.
308 if restricted_shadowing
309 && binding.expansion != LocalExpnId::ROOT
310 && binding.res() != shadowed_glob.res()
312 self.ambiguity_errors.push(AmbiguityError {
313 kind: AmbiguityKind::GlobVsExpanded,
317 misc1: AmbiguityErrorMisc::None,
318 misc2: AmbiguityErrorMisc::None,
323 if !self.is_accessible_from(binding.vis, parent_scope.module) {
324 self.privacy_errors.push(PrivacyError {
327 dedup_span: path_span,
336 // Items and single imports are not shadowable, if we have one, then it's determined.
337 if let Some(binding) = resolution.binding {
338 if !binding.is_glob_import() {
339 return check_usable(self, binding);
343 // --- From now on we either have a glob resolution or no resolution. ---
345 // Check if one of single imports can still define the name,
346 // if it can then our result is not determined and can be invalidated.
347 for single_import in &resolution.single_imports {
348 if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) {
351 let module = match single_import.imported_module.get() {
353 None => return Err((Undetermined, Weak::No)),
355 let ident = match single_import.kind {
356 ImportKind::Single { source, .. } => source,
359 match self.resolve_ident_in_module(
363 &single_import.parent_scope,
367 Err(Determined) => continue,
369 if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
373 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
377 // So we have a resolution that's from a glob import. This resolution is determined
378 // if it cannot be shadowed by some new item/import expanded from a macro.
379 // This happens either if there are no unexpanded macros, or expanded names cannot
380 // shadow globs (that happens in macro namespace or with restricted shadowing).
382 // Additionally, any macro in any module can plant names in the root module if it creates
383 // `macro_export` macros, so the root module effectively has unresolved invocations if any
384 // module has unresolved invocations.
385 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
386 // progress, we have to ignore those potential unresolved invocations from other modules
387 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
388 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
389 let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty();
390 if let Some(binding) = resolution.binding {
391 if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
392 return check_usable(self, binding);
394 return Err((Undetermined, Weak::No));
398 // --- From now on we have no resolution. ---
400 // Now we are in situation when new item/import can appear only from a glob or a macro
401 // expansion. With restricted shadowing names from globs and macro expansions cannot
402 // shadow names from outer scopes, so we can freely fallback from module search to search
403 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
404 // scopes we return `Undetermined` with `Weak::Yes`.
406 // Check if one of unexpanded macros can still define the name,
407 // if it can then our "no resolution" result is not determined and can be invalidated.
408 if unexpanded_macros {
409 return Err((Undetermined, Weak::Yes));
412 // Check if one of glob imports can still define the name,
413 // if it can then our "no resolution" result is not determined and can be invalidated.
414 for glob_import in module.globs.borrow().iter() {
415 if !self.is_accessible_from(glob_import.vis.get(), parent_scope.module) {
418 let module = match glob_import.imported_module.get() {
419 Some(ModuleOrUniformRoot::Module(module)) => module,
421 None => return Err((Undetermined, Weak::Yes)),
423 let tmp_parent_scope;
424 let (mut adjusted_parent_scope, mut ident) =
425 (parent_scope, ident.normalize_to_macros_2_0());
426 match ident.span.glob_adjust(module.expansion, glob_import.span) {
429 ParentScope { module: self.expn_def_scope(def), ..*parent_scope };
430 adjusted_parent_scope = &tmp_parent_scope;
435 let result = self.resolve_ident_in_module_unadjusted(
436 ModuleOrUniformRoot::Module(module),
439 adjusted_parent_scope,
445 Err(Determined) => continue,
447 if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
451 Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
455 // No resolution and no one else can define the name - determinate error.
456 Err((Determined, Weak::No))
459 // Given a binding and an import that resolves to it,
460 // return the corresponding binding defined by the import.
463 binding: &'a NameBinding<'a>,
464 import: &'a Import<'a>,
465 ) -> &'a NameBinding<'a> {
466 let vis = if binding.vis.is_at_least(import.vis.get(), self)
467 || pub_use_of_private_extern_crate_hack(import, binding)
474 if let ImportKind::Glob { ref max_vis, .. } = import.kind {
475 if vis == import.vis.get() || vis.is_at_least(max_vis.get(), self) {
480 self.arenas.alloc_name_binding(NameBinding {
481 kind: NameBindingKind::Import { binding, import, used: Cell::new(false) },
485 expansion: import.parent_scope.expansion,
489 // Define the name or return the existing binding if there is a collision.
494 binding: &'a NameBinding<'a>,
495 ) -> Result<(), &'a NameBinding<'a>> {
496 let res = binding.res();
497 self.check_reserved_macro_name(key.ident, res);
498 self.set_binding_parent_module(binding, module);
499 self.update_resolution(module, key, |this, resolution| {
500 if let Some(old_binding) = resolution.binding {
502 // Do not override real bindings with `Res::Err`s from error recovery.
505 match (old_binding.is_glob_import(), binding.is_glob_import()) {
507 if res != old_binding.res() {
508 resolution.binding = Some(this.ambiguity(
509 AmbiguityKind::GlobVsGlob,
513 } else if !old_binding.vis.is_at_least(binding.vis, &*this) {
514 // We are glob-importing the same item but with greater visibility.
515 resolution.binding = Some(binding);
518 (old_glob @ true, false) | (old_glob @ false, true) => {
519 let (glob_binding, nonglob_binding) =
520 if old_glob { (old_binding, binding) } else { (binding, old_binding) };
521 if glob_binding.res() != nonglob_binding.res()
523 && nonglob_binding.expansion != LocalExpnId::ROOT
525 resolution.binding = Some(this.ambiguity(
526 AmbiguityKind::GlobVsExpanded,
531 resolution.binding = Some(nonglob_binding);
533 resolution.shadowed_glob = Some(glob_binding);
536 return Err(old_binding);
540 resolution.binding = Some(binding);
550 primary_binding: &'a NameBinding<'a>,
551 secondary_binding: &'a NameBinding<'a>,
552 ) -> &'a NameBinding<'a> {
553 self.arenas.alloc_name_binding(NameBinding {
554 ambiguity: Some((secondary_binding, kind)),
555 ..primary_binding.clone()
559 // Use `f` to mutate the resolution of the name in the module.
560 // If the resolution becomes a success, define it in the module's glob importers.
561 fn update_resolution<T, F>(&mut self, module: Module<'a>, key: BindingKey, f: F) -> T
563 F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T,
565 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
566 // during which the resolution might end up getting re-defined via a glob cycle.
568 let resolution = &mut *self.resolution(module, key).borrow_mut();
569 let old_binding = resolution.binding();
571 let t = f(self, resolution);
573 match resolution.binding() {
574 _ if old_binding.is_some() => return t,
576 Some(binding) => match old_binding {
577 Some(old_binding) if ptr::eq(old_binding, binding) => return t,
583 // Define `binding` in `module`s glob importers.
584 for import in module.glob_importers.borrow_mut().iter() {
585 let mut ident = key.ident;
586 let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) {
587 Some(Some(def)) => self.expn_def_scope(def),
588 Some(None) => import.parent_scope.module,
591 if self.is_accessible_from(binding.vis, scope) {
592 let imported_binding = self.import(binding, import);
593 let key = BindingKey { ident, ..key };
594 let _ = self.try_define(import.parent_scope.module, key, imported_binding);
601 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
603 fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
604 if let ImportKind::Single { target, .. } = import.kind {
605 let dummy_binding = self.dummy_binding;
606 let dummy_binding = self.import(dummy_binding, import);
607 self.per_ns(|this, ns| {
608 let key = this.new_key(target, ns);
609 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
611 // Consider erroneous imports used to avoid duplicate diagnostics.
612 self.record_use(target, dummy_binding, false);
617 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
618 /// import errors within the same use tree into a single diagnostic.
619 #[derive(Debug, Clone)]
620 struct UnresolvedImportError {
622 label: Option<String>,
624 suggestion: Option<Suggestion>,
627 pub struct ImportResolver<'a, 'b> {
628 pub r: &'a mut Resolver<'b>,
631 impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> {
632 fn parent(self, id: DefId) -> Option<DefId> {
637 impl<'a, 'b> ImportResolver<'a, 'b> {
640 // This is a fixed-point algorithm. We resolve imports until our efforts
641 // are stymied by an unresolved import; then we bail out of the current
642 // module and continue. We terminate successfully once no more imports
643 // remain or unsuccessfully when no forward progress in resolving imports
646 /// Resolves all imports for the crate. This method performs the fixed-
648 pub fn resolve_imports(&mut self) {
649 let mut prev_num_indeterminates = self.r.indeterminate_imports.len() + 1;
650 while self.r.indeterminate_imports.len() < prev_num_indeterminates {
651 prev_num_indeterminates = self.r.indeterminate_imports.len();
652 for import in mem::take(&mut self.r.indeterminate_imports) {
653 match self.resolve_import(&import) {
654 true => self.r.determined_imports.push(import),
655 false => self.r.indeterminate_imports.push(import),
661 pub fn finalize_imports(&mut self) {
662 for module in self.r.arenas.local_modules().iter() {
663 self.finalize_resolutions_in(module);
666 let mut seen_spans = FxHashSet::default();
667 let mut errors = vec![];
668 let mut prev_root_id: NodeId = NodeId::from_u32(0);
669 let determined_imports = mem::take(&mut self.r.determined_imports);
670 let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports);
672 for (is_indeterminate, import) in determined_imports
675 .chain(indeterminate_imports.into_iter().map(|i| (true, i)))
677 if let Some(err) = self.finalize_import(import) {
678 if let ImportKind::Single { source, ref source_bindings, .. } = import.kind {
679 if source.name == kw::SelfLower {
680 // Silence `unresolved import` error if E0429 is already emitted
681 if let Err(Determined) = source_bindings.value_ns.get() {
687 // If the error is a single failed import then create a "fake" import
688 // resolution for it so that later resolve stages won't complain.
689 self.r.import_dummy_binding(import);
690 if prev_root_id.as_u32() != 0
691 && prev_root_id.as_u32() != import.root_id.as_u32()
692 && !errors.is_empty()
694 // In the case of a new import line, throw a diagnostic message
695 // for the previous line.
696 self.throw_unresolved_import_error(errors, None);
699 if seen_spans.insert(err.span) {
700 let path = import_path_to_string(
701 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
705 errors.push((path, err));
706 prev_root_id = import.root_id;
708 } else if is_indeterminate {
709 // Consider erroneous imports used to avoid duplicate diagnostics.
710 self.r.used_imports.insert(import.id);
711 let path = import_path_to_string(
712 &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
716 let err = UnresolvedImportError {
722 errors.push((path, err));
726 if !errors.is_empty() {
727 self.throw_unresolved_import_error(errors, None);
731 fn throw_unresolved_import_error(
733 errors: Vec<(String, UnresolvedImportError)>,
734 span: Option<MultiSpan>,
736 /// Upper limit on the number of `span_label` messages.
737 const MAX_LABEL_COUNT: usize = 10;
739 let (span, msg) = if errors.is_empty() {
740 (span.unwrap(), "unresolved import".to_string())
742 let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
744 let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::<Vec<_>>();
746 let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
751 let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg);
753 if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() {
754 for message in note {
759 for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) {
760 if let Some(label) = err.label {
761 diag.span_label(err.span, label);
764 if let Some((suggestions, msg, applicability)) = err.suggestion {
765 diag.multipart_suggestion(&msg, suggestions, applicability);
772 /// Attempts to resolve the given import, returning true if its resolution is determined.
773 /// If successful, the resolved bindings are written into the module.
774 fn resolve_import(&mut self, import: &'b Import<'b>) -> bool {
776 "(resolving import for module) resolving import `{}::...` in `{}`",
777 Segment::names_to_string(&import.module_path),
778 module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
781 let module = if let Some(module) = import.imported_module.get() {
784 // For better failure detection, pretend that the import will
785 // not define any names while resolving its module path.
786 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
787 let path_res = self.r.resolve_path(
790 &import.parent_scope,
795 import.vis.set(orig_vis);
798 PathResult::Module(module) => module,
799 PathResult::Indeterminate => return false,
800 PathResult::NonModule(..) | PathResult::Failed { .. } => return true,
804 import.imported_module.set(Some(module));
805 let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
813 } => (source, target, source_bindings, target_bindings, type_ns_only),
814 ImportKind::Glob { .. } => {
815 self.resolve_glob_import(import);
821 let mut indeterminate = false;
822 self.r.per_ns(|this, ns| {
823 if !type_ns_only || ns == TypeNS {
824 if let Err(Undetermined) = source_bindings[ns].get() {
825 // For better failure detection, pretend that the import will
826 // not define any names while resolving its module path.
827 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
828 let binding = this.resolve_ident_in_module(
832 &import.parent_scope,
836 import.vis.set(orig_vis);
838 source_bindings[ns].set(binding);
843 let parent = import.parent_scope.module;
844 match source_bindings[ns].get() {
845 Err(Undetermined) => indeterminate = true,
846 // Don't update the resolution, because it was never added.
847 Err(Determined) if target.name == kw::Underscore => {}
849 let key = this.new_key(target, ns);
850 this.update_resolution(parent, key, |_, resolution| {
851 resolution.single_imports.remove(&PtrKey(import));
854 Ok(binding) if !binding.is_importable() => {
855 let msg = format!("`{}` is not directly importable", target);
856 struct_span_err!(this.session, import.span, E0253, "{}", &msg)
857 .span_label(import.span, "cannot be imported directly")
859 // Do not import this illegal binding. Import a dummy binding and pretend
860 // everything is fine
861 this.import_dummy_binding(import);
864 let imported_binding = this.import(binding, import);
865 target_bindings[ns].set(Some(imported_binding));
866 this.define(parent, target, ns, imported_binding);
875 /// Performs final import resolution, consistency checks and error reporting.
877 /// Optionally returns an unresolved import error. This error is buffered and used to
878 /// consolidate multiple unresolved import errors into a single diagnostic.
879 fn finalize_import(&mut self, import: &'b Import<'b>) -> Option<UnresolvedImportError> {
880 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
881 let orig_unusable_binding = match &import.kind {
882 ImportKind::Single { target_bindings, .. } => {
883 Some(mem::replace(&mut self.r.unusable_binding, target_bindings[TypeNS].get()))
887 let prev_ambiguity_errors_len = self.r.ambiguity_errors.len();
888 let path_res = self.r.resolve_path(
891 &import.parent_scope,
896 let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len;
897 if let Some(orig_unusable_binding) = orig_unusable_binding {
898 self.r.unusable_binding = orig_unusable_binding;
900 import.vis.set(orig_vis);
901 if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
902 // Consider erroneous imports used to avoid duplicate diagnostics.
903 self.r.used_imports.insert(import.id);
905 let module = match path_res {
906 PathResult::Module(module) => {
907 // Consistency checks, analogous to `finalize_macro_resolutions`.
908 if let Some(initial_module) = import.imported_module.get() {
909 if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity {
910 span_bug!(import.span, "inconsistent resolution for an import");
912 } else if self.r.privacy_errors.is_empty() {
913 let msg = "cannot determine resolution for the import";
914 let msg_note = "import resolution is stuck, try simplifying other imports";
915 self.r.session.struct_span_err(import.span, msg).note(msg_note).emit();
920 PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => {
922 assert!(import.imported_module.get().is_none());
924 .report_error(span, ResolutionError::FailedToResolve { label, suggestion });
928 PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => {
930 assert!(import.imported_module.get().is_none());
931 let err = match self.make_path_suggestion(
933 import.module_path.clone(),
934 &import.parent_scope,
936 Some((suggestion, note)) => UnresolvedImportError {
941 vec![(span, Segment::names_to_string(&suggestion))],
942 String::from("a similar path exists"),
943 Applicability::MaybeIncorrect,
946 None => UnresolvedImportError {
957 PathResult::NonModule(_) => {
959 assert!(import.imported_module.get().is_none());
961 // The error was already reported earlier.
964 PathResult::Indeterminate => unreachable!(),
967 let (ident, target, source_bindings, target_bindings, type_ns_only) = match import.kind {
975 } => (source, target, source_bindings, target_bindings, type_ns_only),
976 ImportKind::Glob { is_prelude, ref max_vis } => {
977 if import.module_path.len() <= 1 {
978 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
979 // 2 segments, so the `resolve_path` above won't trigger it.
980 let mut full_path = import.module_path.clone();
981 full_path.push(Segment::from_ident(Ident::empty()));
982 self.r.lint_if_path_starts_with_module(
990 if let ModuleOrUniformRoot::Module(module) = module {
991 if ptr::eq(module, import.parent_scope.module) {
992 // Importing a module into itself is not allowed.
993 return Some(UnresolvedImportError {
995 label: Some(String::from("cannot glob-import a module into itself")),
1002 max_vis.get() != ty::Visibility::Invisible && // Allow empty globs.
1003 !max_vis.get().is_at_least(import.vis.get(), &*self)
1005 let msg = "glob import doesn't reexport anything because no candidate is public enough";
1006 self.r.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
1010 _ => unreachable!(),
1013 let mut all_ns_err = true;
1014 self.r.per_ns(|this, ns| {
1015 if !type_ns_only || ns == TypeNS {
1016 let orig_vis = import.vis.replace(ty::Visibility::Invisible);
1017 let orig_unusable_binding =
1018 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1019 let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true);
1020 let binding = this.resolve_ident_in_module(
1024 &import.parent_scope,
1028 this.last_import_segment = orig_last_import_segment;
1029 this.unusable_binding = orig_unusable_binding;
1030 import.vis.set(orig_vis);
1034 // Consistency checks, analogous to `finalize_macro_resolutions`.
1035 let initial_res = source_bindings[ns].get().map(|initial_binding| {
1037 if let Some(target_binding) = target_bindings[ns].get() {
1038 if target.name == kw::Underscore
1039 && initial_binding.is_extern_crate()
1040 && !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");
1056 } else if res != Res::Err
1057 && this.ambiguity_errors.is_empty()
1058 && this.privacy_errors.is_empty()
1060 let msg = "cannot determine resolution for the import";
1062 "import resolution is stuck, try simplifying other imports";
1063 this.session.struct_span_err(import.span, msg).note(msg_note).emit();
1067 // FIXME: This assert may fire if public glob is later shadowed by a private
1068 // single import (see test `issue-55884-2.rs`). In theory single imports should
1069 // always block globs, even if they are not yet resolved, so that this kind of
1070 // self-inconsistent resolution never happens.
1071 // Re-enable the assert when the issue is fixed.
1072 // assert!(result[ns].get().is_err());
1079 let mut all_ns_failed = true;
1080 self.r.per_ns(|this, ns| {
1081 if !type_ns_only || ns == TypeNS {
1082 let binding = this.resolve_ident_in_module(
1086 &import.parent_scope,
1090 if binding.is_ok() {
1091 all_ns_failed = false;
1096 return if all_ns_failed {
1097 let resolutions = match module {
1098 ModuleOrUniformRoot::Module(module) => {
1099 Some(self.r.resolutions(module).borrow())
1103 let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter());
1104 let names = resolutions
1105 .filter_map(|(BindingKey { ident: i, .. }, resolution)| {
1108 } // Never suggest the same name
1109 match *resolution.borrow() {
1110 NameResolution { binding: Some(name_binding), .. } => {
1111 match name_binding.kind {
1112 NameBindingKind::Import { binding, .. } => {
1113 match binding.kind {
1114 // Never suggest the name that has binding error
1115 // i.e., the name that cannot be previously resolved
1116 NameBindingKind::Res(Res::Err, _) => None,
1123 NameResolution { ref single_imports, .. }
1124 if single_imports.is_empty() =>
1131 .collect::<Vec<Symbol>>();
1133 let lev_suggestion =
1134 find_best_match_for_name(&names, ident.name, None).map(|suggestion| {
1136 vec![(ident.span, suggestion.to_string())],
1137 String::from("a similar name exists in the module"),
1138 Applicability::MaybeIncorrect,
1142 let (suggestion, note) =
1143 match self.check_for_module_export_macro(import, module, ident) {
1144 Some((suggestion, note)) => (suggestion.or(lev_suggestion), note),
1145 _ => (lev_suggestion, Vec::new()),
1148 let label = match module {
1149 ModuleOrUniformRoot::Module(module) => {
1150 let module_str = module_to_string(module);
1151 if let Some(module_str) = module_str {
1152 format!("no `{}` in `{}`", ident, module_str)
1154 format!("no `{}` in the root", ident)
1158 if !ident.is_path_segment_keyword() {
1159 format!("no external crate `{}`", ident)
1161 // HACK(eddyb) this shows up for `self` & `super`, which
1162 // should work instead - for now keep the same error message.
1163 format!("no `{}` in the root", ident)
1168 Some(UnresolvedImportError {
1175 // `resolve_ident_in_module` reported a privacy error.
1176 self.r.import_dummy_binding(import);
1181 let mut reexport_error = None;
1182 let mut any_successful_reexport = false;
1183 self.r.per_ns(|this, ns| {
1184 if let Ok(binding) = source_bindings[ns].get() {
1185 let vis = import.vis.get();
1186 if !binding.vis.is_at_least(vis, &*this) {
1187 reexport_error = Some((ns, binding));
1189 any_successful_reexport = true;
1194 // All namespaces must be re-exported with extra visibility for an error to occur.
1195 if !any_successful_reexport {
1196 let (ns, binding) = reexport_error.unwrap();
1197 if pub_use_of_private_extern_crate_hack(import, binding) {
1199 "extern crate `{}` is private, and cannot be \
1200 re-exported (error E0365), consider declaring with \
1204 self.r.lint_buffer.buffer_lint(
1205 PUB_USE_OF_PRIVATE_EXTERN_CRATE,
1210 } else if ns == TypeNS {
1215 "`{}` is private, and cannot be re-exported",
1218 .span_label(import.span, format!("re-export of private `{}`", ident))
1219 .note(&format!("consider declaring type or module `{}` with `pub`", ident))
1222 let msg = format!("`{}` is private, and cannot be re-exported", ident);
1224 format!("consider marking `{}` as `pub` in the imported module", ident,);
1225 struct_span_err!(self.r.session, import.span, E0364, "{}", &msg)
1226 .span_note(import.span, ¬e_msg)
1231 if import.module_path.len() <= 1 {
1232 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1233 // 2 segments, so the `resolve_path` above won't trigger it.
1234 let mut full_path = import.module_path.clone();
1235 full_path.push(Segment::from_ident(ident));
1236 self.r.per_ns(|this, ns| {
1237 if let Ok(binding) = source_bindings[ns].get() {
1238 this.lint_if_path_starts_with_module(
1239 import.crate_lint(),
1248 // Record what this import resolves to for later uses in documentation,
1249 // this may resolve to either a value or a type, but for documentation
1250 // purposes it's good enough to just favor one over the other.
1251 self.r.per_ns(|this, ns| {
1252 if let Ok(binding) = source_bindings[ns].get() {
1253 this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res());
1257 self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target);
1259 debug!("(resolving single import) successfully resolved import");
1263 fn check_for_redundant_imports(
1266 import: &'b Import<'b>,
1267 source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>,
1268 target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>,
1271 // Skip if the import was produced by a macro.
1272 if import.parent_scope.expansion != LocalExpnId::ROOT {
1276 // Skip if we are inside a named module (in contrast to an anonymous
1277 // module defined by a block).
1278 if let ModuleKind::Def(..) = import.parent_scope.module.kind {
1282 let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1284 let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
1286 self.r.per_ns(|this, ns| {
1287 if let Ok(binding) = source_bindings[ns].get() {
1288 if binding.res() == Res::Err {
1292 let orig_unusable_binding =
1293 mem::replace(&mut this.unusable_binding, target_bindings[ns].get());
1295 match this.early_resolve_ident_in_lexical_scope(
1297 ScopeSet::All(ns, false),
1298 &import.parent_scope,
1303 Ok(other_binding) => {
1304 is_redundant[ns] = Some(
1305 binding.res() == other_binding.res() && !other_binding.is_ambiguity(),
1307 redundant_span[ns] = Some((other_binding.span, other_binding.is_import()));
1309 Err(_) => is_redundant[ns] = Some(false),
1312 this.unusable_binding = orig_unusable_binding;
1316 if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant)
1318 let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
1319 redundant_spans.sort();
1320 redundant_spans.dedup();
1321 self.r.lint_buffer.buffer_lint_with_diagnostic(
1325 &format!("the item `{}` is imported redundantly", ident),
1326 BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
1331 fn resolve_glob_import(&mut self, import: &'b Import<'b>) {
1332 let module = match import.imported_module.get().unwrap() {
1333 ModuleOrUniformRoot::Module(module) => module,
1335 self.r.session.span_err(import.span, "cannot glob-import all possible crates");
1340 if module.is_trait() {
1341 self.r.session.span_err(import.span, "items in traits are not importable");
1343 } else if ptr::eq(module, import.parent_scope.module) {
1345 } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind {
1346 self.r.prelude = Some(module);
1350 // Add to module's glob_importers
1351 module.glob_importers.borrow_mut().push(import);
1353 // Ensure that `resolutions` isn't borrowed during `try_define`,
1354 // since it might get updated via a glob cycle.
1357 .resolutions(module)
1360 .filter_map(|(key, resolution)| {
1361 resolution.borrow().binding().map(|binding| (*key, binding))
1363 .collect::<Vec<_>>();
1364 for (mut key, binding) in bindings {
1365 let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) {
1366 Some(Some(def)) => self.r.expn_def_scope(def),
1367 Some(None) => import.parent_scope.module,
1370 if self.r.is_accessible_from(binding.vis, scope) {
1371 let imported_binding = self.r.import(binding, import);
1372 let _ = self.r.try_define(import.parent_scope.module, key, imported_binding);
1376 // Record the destination of this import
1377 self.r.record_partial_res(import.id, PartialRes::new(module.res().unwrap()));
1380 // Miscellaneous post-processing, including recording re-exports,
1381 // reporting conflicts, and reporting unresolved imports.
1382 fn finalize_resolutions_in(&mut self, module: Module<'b>) {
1383 // Since import resolution is finished, globs will not define any more names.
1384 *module.globs.borrow_mut() = Vec::new();
1386 let mut reexports = Vec::new();
1388 module.for_each_child(self.r, |_, ident, _, binding| {
1389 // Filter away ambiguous imports and anything that has def-site hygiene.
1390 // FIXME: Implement actual cross-crate hygiene.
1391 let is_good_import =
1392 binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion();
1393 if is_good_import || binding.is_macro_def() {
1394 let res = binding.res().expect_non_local();
1395 if res != def::Res::Err {
1396 reexports.push(Export { ident, res, span: binding.span, vis: binding.vis });
1401 if !reexports.is_empty() {
1402 if let Some(def_id) = module.opt_def_id() {
1403 // Call to `expect_local` should be fine because current
1404 // code is only called for local modules.
1405 self.r.export_map.insert(def_id.expect_local(), reexports);
1411 fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, span: Span) -> String {
1412 let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot);
1413 let global = !names.is_empty() && names[0].name == kw::PathRoot;
1414 if let Some(pos) = pos {
1415 let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] };
1416 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>())
1418 let names = if global { &names[1..] } else { names };
1419 if names.is_empty() {
1420 import_kind_to_string(import_kind)
1424 names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()),
1425 import_kind_to_string(import_kind),
1431 fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String {
1433 ImportKind::Single { source, .. } => source.to_string(),
1434 ImportKind::Glob { .. } => "*".to_string(),
1435 ImportKind::ExternCrate { .. } => "<extern crate>".to_string(),
1436 ImportKind::MacroUse => "#[macro_use]".to_string(),