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
::util
::lev_distance
::find_best_match_for_name
;
14 use rustc_ast
::NodeId
;
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(),