1 //! A bunch of methods and structures more or less related to resolving imports.
3 use crate::diagnostics
::Suggestion
;
4 use crate::Determinacy
::{self, *}
;
5 use crate::Namespace
::{self, MacroNS, TypeNS}
;
6 use crate::{module_to_string, names_to_string}
;
7 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind}
;
8 use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment}
;
9 use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak}
;
10 use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding}
;
12 use rustc_ast
::unwrap_or
;
13 use rustc_ast
::NodeId
;
14 use rustc_ast_lowering
::ResolverAstLowering
;
15 use rustc_data_structures
::fx
::FxHashSet
;
16 use rustc_data_structures
::ptr_key
::PtrKey
;
17 use rustc_errors
::{pluralize, struct_span_err, Applicability}
;
18 use rustc_hir
::def
::{self, PartialRes}
;
19 use rustc_hir
::def_id
::DefId
;
20 use rustc_middle
::hir
::exports
::Export
;
21 use rustc_middle
::span_bug
;
23 use rustc_session
::lint
::builtin
::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS}
;
24 use rustc_session
::lint
::BuiltinLintDiagnostics
;
25 use rustc_span
::hygiene
::LocalExpnId
;
26 use rustc_span
::lev_distance
::find_best_match_for_name
;
27 use rustc_span
::symbol
::{kw, Ident, Symbol}
;
28 use rustc_span
::{MultiSpan, Span}
;
35 type Res
= def
::Res
<NodeId
>;
37 /// Contains data for specific kinds of imports.
38 #[derive(Clone, Debug)]
39 pub enum ImportKind
<'a
> {
41 /// `source` in `use prefix::source as target`.
43 /// `target` in `use prefix::source as target`.
45 /// Bindings to which `source` refers to.
46 source_bindings
: PerNS
<Cell
<Result
<&'a NameBinding
<'a
>, Determinacy
>>>,
47 /// Bindings introduced by `target`.
48 target_bindings
: PerNS
<Cell
<Option
<&'a NameBinding
<'a
>>>>,
49 /// `true` for `...::{self [as target]}` imports, `false` otherwise.
51 /// Did this import result from a nested import? ie. `use foo::{bar, baz};`
56 max_vis
: Cell
<ty
::Visibility
>, // The visibility of the greatest re-export.
57 // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
60 source
: Option
<Symbol
>,
67 #[derive(Debug, Clone)]
68 crate struct Import
<'a
> {
69 pub kind
: ImportKind
<'a
>,
71 /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`.
73 /// In the case where the `Import` was expanded from a "nested" use tree,
74 /// this id is the ID of the leaf tree. For example:
76 /// ```ignore (pacify the mercilous tidy)
77 /// use foo::bar::{a, b}
80 /// If this is the import for `foo::bar::a`, we would have the ID of the `UseTree`
81 /// for `a` in this field.
84 /// The `id` of the "root" use-kind -- this is always the same as
85 /// `id` except in the case of "nested" use trees, in which case
86 /// it will be the `id` of the root use tree. e.g., in the example
87 /// from `id`, this would be the ID of the `use foo::bar`
91 /// Span of the entire use statement.
94 /// Span of the entire use statement with attributes.
95 pub use_span_with_attributes
: Span
,
97 /// Did the use statement have any attributes?
98 pub has_attributes
: bool
,
100 /// Span of this use tree.
103 /// Span of the *root* use tree (see `root_id`).
106 pub parent_scope
: ParentScope
<'a
>,
107 pub module_path
: Vec
<Segment
>,
108 /// The resolution of `module_path`.
109 pub imported_module
: Cell
<Option
<ModuleOrUniformRoot
<'a
>>>,
110 pub vis
: Cell
<ty
::Visibility
>,
111 pub used
: Cell
<bool
>,
114 impl<'a
> Import
<'a
> {
115 pub fn is_glob(&self) -> bool
{
116 matches
!(self.kind
, ImportKind
::Glob { .. }
)
119 pub fn is_nested(&self) -> bool
{
121 ImportKind
::Single { nested, .. }
=> nested
,
126 crate fn crate_lint(&self) -> CrateLint
{
127 CrateLint
::UsePath { root_id: self.root_id, root_span: self.root_span }
131 #[derive(Clone, Default, Debug)]
132 /// Records information about the resolution of a name in a namespace of a module.
133 pub struct NameResolution
<'a
> {
134 /// Single imports that may define the name in the namespace.
135 /// Imports are arena-allocated, so it's ok to use pointers as keys.
136 single_imports
: FxHashSet
<PtrKey
<'a
, Import
<'a
>>>,
137 /// The least shadowable known binding for this name, or None if there are no known bindings.
138 pub binding
: Option
<&'a NameBinding
<'a
>>,
139 shadowed_glob
: Option
<&'a NameBinding
<'a
>>,
142 impl<'a
> NameResolution
<'a
> {
143 // Returns the binding for the name if it is known or None if it not known.
144 pub(crate) fn binding(&self) -> Option
<&'a NameBinding
<'a
>> {
145 self.binding
.and_then(|binding
| {
146 if !binding
.is_glob_import() || self.single_imports
.is_empty() {
154 crate fn add_single_import(&mut self, import
: &'a Import
<'a
>) {
155 self.single_imports
.insert(PtrKey(import
));
159 // Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;`
160 // are permitted for backward-compatibility under a deprecation lint.
161 fn pub_use_of_private_extern_crate_hack(import
: &Import
<'_
>, binding
: &NameBinding
<'_
>) -> bool
{
162 match (&import
.kind
, &binding
.kind
) {
164 ImportKind
::Single { .. }
,
165 NameBindingKind
::Import
{
166 import
: Import { kind: ImportKind::ExternCrate { .. }
, .. },
169 ) => import
.vis
.get() == ty
::Visibility
::Public
,
174 impl<'a
> Resolver
<'a
> {
175 crate fn resolve_ident_in_module_unadjusted(
177 module
: ModuleOrUniformRoot
<'a
>,
180 parent_scope
: &ParentScope
<'a
>,
183 ) -> Result
<&'a NameBinding
<'a
>, Determinacy
> {
184 self.resolve_ident_in_module_unadjusted_ext(
193 .map_err(|(determinacy
, _
)| determinacy
)
196 /// Attempts to resolve `ident` in namespaces `ns` of `module`.
197 /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete.
198 crate fn resolve_ident_in_module_unadjusted_ext(
200 module
: ModuleOrUniformRoot
<'a
>,
203 parent_scope
: &ParentScope
<'a
>,
204 restricted_shadowing
: bool
,
207 ) -> Result
<&'a NameBinding
<'a
>, (Determinacy
, Weak
)> {
208 let module
= match module
{
209 ModuleOrUniformRoot
::Module(module
) => module
,
210 ModuleOrUniformRoot
::CrateRootAndExternPrelude
=> {
211 assert
!(!restricted_shadowing
);
212 let binding
= self.early_resolve_ident_in_lexical_scope(
214 ScopeSet
::AbsolutePath(ns
),
220 return binding
.map_err(|determinacy
| (determinacy
, Weak
::No
));
222 ModuleOrUniformRoot
::ExternPrelude
=> {
223 assert
!(!restricted_shadowing
);
224 return if ns
!= TypeNS
{
225 Err((Determined
, Weak
::No
))
226 } else if let Some(binding
) = self.extern_prelude_get(ident
, !record_used
) {
228 } else if !self.graph_root
.unexpanded_invocations
.borrow().is_empty() {
229 // Macro-expanded `extern crate` items can add names to extern prelude.
230 Err((Undetermined
, Weak
::No
))
232 Err((Determined
, Weak
::No
))
235 ModuleOrUniformRoot
::CurrentScope
=> {
236 assert
!(!restricted_shadowing
);
238 if ident
.name
== kw
::Crate
|| ident
.name
== kw
::DollarCrate
{
239 let module
= self.resolve_crate_root(ident
);
241 (module
, ty
::Visibility
::Public
, module
.span
, LocalExpnId
::ROOT
)
242 .to_name_binding(self.arenas
);
244 } else if ident
.name
== kw
::Super
|| ident
.name
== kw
::SelfLower
{
245 // FIXME: Implement these with renaming requirements so that e.g.
246 // `use super;` doesn't work, but `use super as name;` does.
247 // Fall through here to get an error from `early_resolve_...`.
251 let scopes
= ScopeSet
::All(ns
, true);
252 let binding
= self.early_resolve_ident_in_lexical_scope(
260 return binding
.map_err(|determinacy
| (determinacy
, Weak
::No
));
264 let key
= self.new_key(ident
, ns
);
266 self.resolution(module
, key
).try_borrow_mut().map_err(|_
| (Determined
, Weak
::No
))?
; // This happens when there is a cycle of imports.
268 if let Some(binding
) = resolution
.binding
{
269 if !restricted_shadowing
&& binding
.expansion
!= LocalExpnId
::ROOT
{
270 if let NameBindingKind
::Res(_
, true) = binding
.kind
{
271 self.macro_expanded_macro_export_errors
.insert((path_span
, binding
.span
));
276 let check_usable
= |this
: &mut Self, binding
: &'a NameBinding
<'a
>| {
277 if let Some(unusable_binding
) = this
.unusable_binding
{
278 if ptr
::eq(binding
, unusable_binding
) {
279 return Err((Determined
, Weak
::No
));
282 let usable
= this
.is_accessible_from(binding
.vis
, parent_scope
.module
);
283 if usable { Ok(binding) }
else { Err((Determined, Weak::No)) }
289 .and_then(|binding
| {
290 // If the primary binding is unusable, search further and return the shadowed glob
291 // binding if it exists. What we really want here is having two separate scopes in
292 // a module - one for non-globs and one for globs, but until that's done use this
293 // hack to avoid inconsistent resolution ICEs during import validation.
294 if let Some(unusable_binding
) = self.unusable_binding
{
295 if ptr
::eq(binding
, unusable_binding
) {
296 return resolution
.shadowed_glob
;
301 .ok_or((Determined
, Weak
::No
))
302 .and_then(|binding
| {
303 if self.last_import_segment
&& check_usable(self, binding
).is_err() {
304 Err((Determined
, Weak
::No
))
306 self.record_use(ident
, binding
, restricted_shadowing
);
308 if let Some(shadowed_glob
) = resolution
.shadowed_glob
{
309 // Forbid expanded shadowing to avoid time travel.
310 if restricted_shadowing
311 && binding
.expansion
!= LocalExpnId
::ROOT
312 && binding
.res() != shadowed_glob
.res()
314 self.ambiguity_errors
.push(AmbiguityError
{
315 kind
: AmbiguityKind
::GlobVsExpanded
,
319 misc1
: AmbiguityErrorMisc
::None
,
320 misc2
: AmbiguityErrorMisc
::None
,
325 if !self.is_accessible_from(binding
.vis
, parent_scope
.module
) {
326 self.privacy_errors
.push(PrivacyError
{
329 dedup_span
: path_span
,
338 // Items and single imports are not shadowable, if we have one, then it's determined.
339 if let Some(binding
) = resolution
.binding
{
340 if !binding
.is_glob_import() {
341 return check_usable(self, binding
);
345 // --- From now on we either have a glob resolution or no resolution. ---
347 // Check if one of single imports can still define the name,
348 // if it can then our result is not determined and can be invalidated.
349 for single_import
in &resolution
.single_imports
{
350 if !self.is_accessible_from(single_import
.vis
.get(), parent_scope
.module
) {
353 let module
= unwrap_or
!(
354 single_import
.imported_module
.get(),
355 return Err((Undetermined
, Weak
::No
))
357 let ident
= match single_import
.kind
{
358 ImportKind
::Single { source, .. }
=> source
,
361 match self.resolve_ident_in_module(
365 &single_import
.parent_scope
,
369 Err(Determined
) => continue,
371 if !self.is_accessible_from(binding
.vis
, single_import
.parent_scope
.module
) =>
375 Ok(_
) | Err(Undetermined
) => return Err((Undetermined
, Weak
::No
)),
379 // So we have a resolution that's from a glob import. This resolution is determined
380 // if it cannot be shadowed by some new item/import expanded from a macro.
381 // This happens either if there are no unexpanded macros, or expanded names cannot
382 // shadow globs (that happens in macro namespace or with restricted shadowing).
384 // Additionally, any macro in any module can plant names in the root module if it creates
385 // `macro_export` macros, so the root module effectively has unresolved invocations if any
386 // module has unresolved invocations.
387 // However, it causes resolution/expansion to stuck too often (#53144), so, to make
388 // progress, we have to ignore those potential unresolved invocations from other modules
389 // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
390 // shadowing is enabled, see `macro_expanded_macro_export_errors`).
391 let unexpanded_macros
= !module
.unexpanded_invocations
.borrow().is_empty();
392 if let Some(binding
) = resolution
.binding
{
393 if !unexpanded_macros
|| ns
== MacroNS
|| restricted_shadowing
{
394 return check_usable(self, binding
);
396 return Err((Undetermined
, Weak
::No
));
400 // --- From now on we have no resolution. ---
402 // Now we are in situation when new item/import can appear only from a glob or a macro
403 // expansion. With restricted shadowing names from globs and macro expansions cannot
404 // shadow names from outer scopes, so we can freely fallback from module search to search
405 // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
406 // scopes we return `Undetermined` with `Weak::Yes`.
408 // Check if one of unexpanded macros can still define the name,
409 // if it can then our "no resolution" result is not determined and can be invalidated.
410 if unexpanded_macros
{
411 return Err((Undetermined
, Weak
::Yes
));
414 // Check if one of glob imports can still define the name,
415 // if it can then our "no resolution" result is not determined and can be invalidated.
416 for glob_import
in module
.globs
.borrow().iter() {
417 if !self.is_accessible_from(glob_import
.vis
.get(), parent_scope
.module
) {
420 let module
= match glob_import
.imported_module
.get() {
421 Some(ModuleOrUniformRoot
::Module(module
)) => module
,
423 None
=> return Err((Undetermined
, Weak
::Yes
)),
425 let tmp_parent_scope
;
426 let (mut adjusted_parent_scope
, mut ident
) =
427 (parent_scope
, ident
.normalize_to_macros_2_0());
428 match ident
.span
.glob_adjust(module
.expansion
, glob_import
.span
) {
431 ParentScope { module: self.macro_def_scope(def), ..*parent_scope }
;
432 adjusted_parent_scope
= &tmp_parent_scope
;
437 let result
= self.resolve_ident_in_module_unadjusted(
438 ModuleOrUniformRoot
::Module(module
),
441 adjusted_parent_scope
,
447 Err(Determined
) => continue,
449 if !self.is_accessible_from(binding
.vis
, glob_import
.parent_scope
.module
) =>
453 Ok(_
) | Err(Undetermined
) => return Err((Undetermined
, Weak
::Yes
)),
457 // No resolution and no one else can define the name - determinate error.
458 Err((Determined
, Weak
::No
))
461 // Given a binding and an import that resolves to it,
462 // return the corresponding binding defined by the import.
465 binding
: &'a NameBinding
<'a
>,
466 import
: &'a Import
<'a
>,
467 ) -> &'a NameBinding
<'a
> {
468 let vis
= if binding
.vis
.is_at_least(import
.vis
.get(), self)
469 || pub_use_of_private_extern_crate_hack(import
, binding
)
476 if let ImportKind
::Glob { ref max_vis, .. }
= import
.kind
{
477 if vis
== import
.vis
.get() || vis
.is_at_least(max_vis
.get(), self) {
482 self.arenas
.alloc_name_binding(NameBinding
{
483 kind
: NameBindingKind
::Import { binding, import, used: Cell::new(false) }
,
487 expansion
: import
.parent_scope
.expansion
,
491 // Define the name or return the existing binding if there is a collision.
496 binding
: &'a NameBinding
<'a
>,
497 ) -> Result
<(), &'a NameBinding
<'a
>> {
498 let res
= binding
.res();
499 self.check_reserved_macro_name(key
.ident
, res
);
500 self.set_binding_parent_module(binding
, module
);
501 self.update_resolution(module
, key
, |this
, resolution
| {
502 if let Some(old_binding
) = resolution
.binding
{
504 // Do not override real bindings with `Res::Err`s from error recovery.
507 match (old_binding
.is_glob_import(), binding
.is_glob_import()) {
509 if res
!= old_binding
.res() {
510 resolution
.binding
= Some(this
.ambiguity(
511 AmbiguityKind
::GlobVsGlob
,
515 } else if !old_binding
.vis
.is_at_least(binding
.vis
, &*this
) {
516 // We are glob-importing the same item but with greater visibility.
517 resolution
.binding
= Some(binding
);
520 (old_glob @
true, false) | (old_glob @
false, true) => {
521 let (glob_binding
, nonglob_binding
) =
522 if old_glob { (old_binding, binding) }
else { (binding, old_binding) }
;
523 if glob_binding
.res() != nonglob_binding
.res()
525 && nonglob_binding
.expansion
!= LocalExpnId
::ROOT
527 resolution
.binding
= Some(this
.ambiguity(
528 AmbiguityKind
::GlobVsExpanded
,
533 resolution
.binding
= Some(nonglob_binding
);
535 resolution
.shadowed_glob
= Some(glob_binding
);
538 return Err(old_binding
);
542 resolution
.binding
= Some(binding
);
552 primary_binding
: &'a NameBinding
<'a
>,
553 secondary_binding
: &'a NameBinding
<'a
>,
554 ) -> &'a NameBinding
<'a
> {
555 self.arenas
.alloc_name_binding(NameBinding
{
556 ambiguity
: Some((secondary_binding
, kind
)),
557 ..primary_binding
.clone()
561 // Use `f` to mutate the resolution of the name in the module.
562 // If the resolution becomes a success, define it in the module's glob importers.
563 fn update_resolution
<T
, F
>(&mut self, module
: Module
<'a
>, key
: BindingKey
, f
: F
) -> T
565 F
: FnOnce(&mut Resolver
<'a
>, &mut NameResolution
<'a
>) -> T
,
567 // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
568 // during which the resolution might end up getting re-defined via a glob cycle.
570 let resolution
= &mut *self.resolution(module
, key
).borrow_mut();
571 let old_binding
= resolution
.binding();
573 let t
= f(self, resolution
);
575 match resolution
.binding() {
576 _
if old_binding
.is_some() => return t
,
578 Some(binding
) => match old_binding
{
579 Some(old_binding
) if ptr
::eq(old_binding
, binding
) => return t
,
585 // Define `binding` in `module`s glob importers.
586 for import
in module
.glob_importers
.borrow_mut().iter() {
587 let mut ident
= key
.ident
;
588 let scope
= match ident
.span
.reverse_glob_adjust(module
.expansion
, import
.span
) {
589 Some(Some(def
)) => self.macro_def_scope(def
),
590 Some(None
) => import
.parent_scope
.module
,
593 if self.is_accessible_from(binding
.vis
, scope
) {
594 let imported_binding
= self.import(binding
, import
);
595 let key
= BindingKey { ident, ..key }
;
596 let _
= self.try_define(import
.parent_scope
.module
, key
, imported_binding
);
603 // Define a "dummy" resolution containing a Res::Err as a placeholder for a
605 fn import_dummy_binding(&mut self, import
: &'a Import
<'a
>) {
606 if let ImportKind
::Single { target, .. }
= import
.kind
{
607 let dummy_binding
= self.dummy_binding
;
608 let dummy_binding
= self.import(dummy_binding
, import
);
609 self.per_ns(|this
, ns
| {
610 let key
= this
.new_key(target
, ns
);
611 let _
= this
.try_define(import
.parent_scope
.module
, key
, dummy_binding
);
613 // Consider erroneous imports used to avoid duplicate diagnostics.
614 self.record_use(target
, dummy_binding
, false);
619 /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved
620 /// import errors within the same use tree into a single diagnostic.
621 #[derive(Debug, Clone)]
622 struct UnresolvedImportError
{
624 label
: Option
<String
>,
626 suggestion
: Option
<Suggestion
>,
629 pub struct ImportResolver
<'a
, 'b
> {
630 pub r
: &'a
mut Resolver
<'b
>,
633 impl<'a
, 'b
> ty
::DefIdTree
for &'a ImportResolver
<'a
, 'b
> {
634 fn parent(self, id
: DefId
) -> Option
<DefId
> {
639 impl<'a
, 'b
> ImportResolver
<'a
, 'b
> {
642 // This is a fixed-point algorithm. We resolve imports until our efforts
643 // are stymied by an unresolved import; then we bail out of the current
644 // module and continue. We terminate successfully once no more imports
645 // remain or unsuccessfully when no forward progress in resolving imports
648 /// Resolves all imports for the crate. This method performs the fixed-
650 pub fn resolve_imports(&mut self) {
651 let mut prev_num_indeterminates
= self.r
.indeterminate_imports
.len() + 1;
652 while self.r
.indeterminate_imports
.len() < prev_num_indeterminates
{
653 prev_num_indeterminates
= self.r
.indeterminate_imports
.len();
654 for import
in mem
::take(&mut self.r
.indeterminate_imports
) {
655 match self.resolve_import(&import
) {
656 true => self.r
.determined_imports
.push(import
),
657 false => self.r
.indeterminate_imports
.push(import
),
663 pub fn finalize_imports(&mut self) {
664 for module
in self.r
.arenas
.local_modules().iter() {
665 self.finalize_resolutions_in(module
);
668 let mut seen_spans
= FxHashSet
::default();
669 let mut errors
= vec
![];
670 let mut prev_root_id
: NodeId
= NodeId
::from_u32(0);
671 let determined_imports
= mem
::take(&mut self.r
.determined_imports
);
672 let indeterminate_imports
= mem
::take(&mut self.r
.indeterminate_imports
);
674 for (is_indeterminate
, import
) in determined_imports
677 .chain(indeterminate_imports
.into_iter().map(|i
| (true, i
)))
679 if let Some(err
) = self.finalize_import(import
) {
680 if let ImportKind
::Single { source, ref source_bindings, .. }
= import
.kind
{
681 if source
.name
== kw
::SelfLower
{
682 // Silence `unresolved import` error if E0429 is already emitted
683 if let Err(Determined
) = source_bindings
.value_ns
.get() {
689 // If the error is a single failed import then create a "fake" import
690 // resolution for it so that later resolve stages won't complain.
691 self.r
.import_dummy_binding(import
);
692 if prev_root_id
.as_u32() != 0
693 && prev_root_id
.as_u32() != import
.root_id
.as_u32()
694 && !errors
.is_empty()
696 // In the case of a new import line, throw a diagnostic message
697 // for the previous line.
698 self.throw_unresolved_import_error(errors
, None
);
701 if seen_spans
.insert(err
.span
) {
702 let path
= import_path_to_string(
703 &import
.module_path
.iter().map(|seg
| seg
.ident
).collect
::<Vec
<_
>>(),
707 errors
.push((path
, err
));
708 prev_root_id
= import
.root_id
;
710 } else if is_indeterminate
{
711 // Consider erroneous imports used to avoid duplicate diagnostics.
712 self.r
.used_imports
.insert(import
.id
);
713 let path
= import_path_to_string(
714 &import
.module_path
.iter().map(|seg
| seg
.ident
).collect
::<Vec
<_
>>(),
718 let err
= UnresolvedImportError
{
724 errors
.push((path
, err
));
728 if !errors
.is_empty() {
729 self.throw_unresolved_import_error(errors
, None
);
733 fn throw_unresolved_import_error(
735 errors
: Vec
<(String
, UnresolvedImportError
)>,
736 span
: Option
<MultiSpan
>,
738 /// Upper limit on the number of `span_label` messages.
739 const MAX_LABEL_COUNT
: usize = 10;
741 let (span
, msg
) = if errors
.is_empty() {
742 (span
.unwrap(), "unresolved import".to_string())
744 let span
= MultiSpan
::from_spans(errors
.iter().map(|(_
, err
)| err
.span
).collect());
746 let paths
= errors
.iter().map(|(path
, _
)| format
!("`{}`", path
)).collect
::<Vec
<_
>>();
748 let msg
= format
!("unresolved import{} {}", pluralize
!(paths
.len()), paths
.join(", "),);
753 let mut diag
= struct_span_err
!(self.r
.session
, span
, E0432
, "{}", &msg
);
755 if let Some((_
, UnresolvedImportError { note, .. }
)) = errors
.iter().last() {
756 for message
in note
{
761 for (_
, err
) in errors
.into_iter().take(MAX_LABEL_COUNT
) {
762 if let Some(label
) = err
.label
{
763 diag
.span_label(err
.span
, label
);
766 if let Some((suggestions
, msg
, applicability
)) = err
.suggestion
{
767 diag
.multipart_suggestion(&msg
, suggestions
, applicability
);
774 /// Attempts to resolve the given import, returning true if its resolution is determined.
775 /// If successful, the resolved bindings are written into the module.
776 fn resolve_import(&mut self, import
: &'b Import
<'b
>) -> bool
{
778 "(resolving import for module) resolving import `{}::...` in `{}`",
779 Segment
::names_to_string(&import
.module_path
),
780 module_to_string(import
.parent_scope
.module
).unwrap_or_else(|| "???".to_string()),
783 let module
= if let Some(module
) = import
.imported_module
.get() {
786 // For better failure detection, pretend that the import will
787 // not define any names while resolving its module path.
788 let orig_vis
= import
.vis
.replace(ty
::Visibility
::Invisible
);
789 let path_res
= self.r
.resolve_path(
792 &import
.parent_scope
,
797 import
.vis
.set(orig_vis
);
800 PathResult
::Module(module
) => module
,
801 PathResult
::Indeterminate
=> return false,
802 PathResult
::NonModule(..) | PathResult
::Failed { .. }
=> return true,
806 import
.imported_module
.set(Some(module
));
807 let (source
, target
, source_bindings
, target_bindings
, type_ns_only
) = match import
.kind
{
815 } => (source
, target
, source_bindings
, target_bindings
, type_ns_only
),
816 ImportKind
::Glob { .. }
=> {
817 self.resolve_glob_import(import
);
823 let mut indeterminate
= false;
824 self.r
.per_ns(|this
, ns
| {
825 if !type_ns_only
|| ns
== TypeNS
{
826 if let Err(Undetermined
) = source_bindings
[ns
].get() {
827 // For better failure detection, pretend that the import will
828 // not define any names while resolving its module path.
829 let orig_vis
= import
.vis
.replace(ty
::Visibility
::Invisible
);
830 let binding
= this
.resolve_ident_in_module(
834 &import
.parent_scope
,
838 import
.vis
.set(orig_vis
);
840 source_bindings
[ns
].set(binding
);
845 let parent
= import
.parent_scope
.module
;
846 match source_bindings
[ns
].get() {
847 Err(Undetermined
) => indeterminate
= true,
848 // Don't update the resolution, because it was never added.
849 Err(Determined
) if target
.name
== kw
::Underscore
=> {}
851 let key
= this
.new_key(target
, ns
);
852 this
.update_resolution(parent
, key
, |_
, resolution
| {
853 resolution
.single_imports
.remove(&PtrKey(import
));
856 Ok(binding
) if !binding
.is_importable() => {
857 let msg
= format
!("`{}` is not directly importable", target
);
858 struct_span_err
!(this
.session
, import
.span
, E0253
, "{}", &msg
)
859 .span_label(import
.span
, "cannot be imported directly")
861 // Do not import this illegal binding. Import a dummy binding and pretend
862 // everything is fine
863 this
.import_dummy_binding(import
);
866 let imported_binding
= this
.import(binding
, import
);
867 target_bindings
[ns
].set(Some(imported_binding
));
868 this
.define(parent
, target
, ns
, imported_binding
);
877 /// Performs final import resolution, consistency checks and error reporting.
879 /// Optionally returns an unresolved import error. This error is buffered and used to
880 /// consolidate multiple unresolved import errors into a single diagnostic.
881 fn finalize_import(&mut self, import
: &'b Import
<'b
>) -> Option
<UnresolvedImportError
> {
882 let orig_vis
= import
.vis
.replace(ty
::Visibility
::Invisible
);
883 let orig_unusable_binding
= match &import
.kind
{
884 ImportKind
::Single { target_bindings, .. }
=> {
885 Some(mem
::replace(&mut self.r
.unusable_binding
, target_bindings
[TypeNS
].get()))
889 let prev_ambiguity_errors_len
= self.r
.ambiguity_errors
.len();
890 let path_res
= self.r
.resolve_path(
893 &import
.parent_scope
,
898 let no_ambiguity
= self.r
.ambiguity_errors
.len() == prev_ambiguity_errors_len
;
899 if let Some(orig_unusable_binding
) = orig_unusable_binding
{
900 self.r
.unusable_binding
= orig_unusable_binding
;
902 import
.vis
.set(orig_vis
);
903 if let PathResult
::Failed { .. }
| PathResult
::NonModule(..) = path_res
{
904 // Consider erroneous imports used to avoid duplicate diagnostics.
905 self.r
.used_imports
.insert(import
.id
);
907 let module
= match path_res
{
908 PathResult
::Module(module
) => {
909 // Consistency checks, analogous to `finalize_macro_resolutions`.
910 if let Some(initial_module
) = import
.imported_module
.get() {
911 if !ModuleOrUniformRoot
::same_def(module
, initial_module
) && no_ambiguity
{
912 span_bug
!(import
.span
, "inconsistent resolution for an import");
914 } else if self.r
.privacy_errors
.is_empty() {
915 let msg
= "cannot determine resolution for the import";
916 let msg_note
= "import resolution is stuck, try simplifying other imports";
917 self.r
.session
.struct_span_err(import
.span
, msg
).note(msg_note
).emit();
922 PathResult
::Failed { is_error_from_last_segment: false, span, label, suggestion }
=> {
924 assert
!(import
.imported_module
.get().is_none());
926 .report_error(span
, ResolutionError
::FailedToResolve { label, suggestion }
);
930 PathResult
::Failed { is_error_from_last_segment: true, span, label, suggestion }
=> {
932 assert
!(import
.imported_module
.get().is_none());
933 let err
= match self.make_path_suggestion(
935 import
.module_path
.clone(),
936 &import
.parent_scope
,
938 Some((suggestion
, note
)) => UnresolvedImportError
{
943 vec
![(span
, Segment
::names_to_string(&suggestion
))],
944 String
::from("a similar path exists"),
945 Applicability
::MaybeIncorrect
,
948 None
=> UnresolvedImportError
{
959 PathResult
::NonModule(_
) => {
961 assert
!(import
.imported_module
.get().is_none());
963 // The error was already reported earlier.
966 PathResult
::Indeterminate
=> unreachable
!(),
969 let (ident
, target
, source_bindings
, target_bindings
, type_ns_only
) = match import
.kind
{
977 } => (source
, target
, source_bindings
, target_bindings
, type_ns_only
),
978 ImportKind
::Glob { is_prelude, ref max_vis }
=> {
979 if import
.module_path
.len() <= 1 {
980 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
981 // 2 segments, so the `resolve_path` above won't trigger it.
982 let mut full_path
= import
.module_path
.clone();
983 full_path
.push(Segment
::from_ident(Ident
::invalid()));
984 self.r
.lint_if_path_starts_with_module(
992 if let ModuleOrUniformRoot
::Module(module
) = module
{
993 if module
.def_id() == import
.parent_scope
.module
.def_id() {
994 // Importing a module into itself is not allowed.
995 return Some(UnresolvedImportError
{
997 label
: Some(String
::from("cannot glob-import a module into itself")),
1004 max_vis
.get() != ty
::Visibility
::Invisible
&& // Allow empty globs.
1005 !max_vis
.get().is_at_least(import
.vis
.get(), &*self)
1007 let msg
= "glob import doesn't reexport anything because no candidate is public enough";
1008 self.r
.lint_buffer
.buffer_lint(UNUSED_IMPORTS
, import
.id
, import
.span
, msg
);
1012 _
=> unreachable
!(),
1015 let mut all_ns_err
= true;
1016 self.r
.per_ns(|this
, ns
| {
1017 if !type_ns_only
|| ns
== TypeNS
{
1018 let orig_vis
= import
.vis
.replace(ty
::Visibility
::Invisible
);
1019 let orig_unusable_binding
=
1020 mem
::replace(&mut this
.unusable_binding
, target_bindings
[ns
].get());
1021 let orig_last_import_segment
= mem
::replace(&mut this
.last_import_segment
, true);
1022 let binding
= this
.resolve_ident_in_module(
1026 &import
.parent_scope
,
1030 this
.last_import_segment
= orig_last_import_segment
;
1031 this
.unusable_binding
= orig_unusable_binding
;
1032 import
.vis
.set(orig_vis
);
1036 // Consistency checks, analogous to `finalize_macro_resolutions`.
1037 let initial_res
= source_bindings
[ns
].get().map(|initial_binding
| {
1039 if let Some(target_binding
) = target_bindings
[ns
].get() {
1040 if target
.name
== kw
::Underscore
1041 && initial_binding
.is_extern_crate()
1042 && !initial_binding
.is_import()
1047 import
.module_path
.is_empty(),
1051 initial_binding
.res()
1053 let res
= binding
.res();
1054 if let Ok(initial_res
) = initial_res
{
1055 if res
!= initial_res
&& this
.ambiguity_errors
.is_empty() {
1056 span_bug
!(import
.span
, "inconsistent resolution for an import");
1058 } else if res
!= Res
::Err
1059 && this
.ambiguity_errors
.is_empty()
1060 && this
.privacy_errors
.is_empty()
1062 let msg
= "cannot determine resolution for the import";
1064 "import resolution is stuck, try simplifying other imports";
1065 this
.session
.struct_span_err(import
.span
, msg
).note(msg_note
).emit();
1069 // FIXME: This assert may fire if public glob is later shadowed by a private
1070 // single import (see test `issue-55884-2.rs`). In theory single imports should
1071 // always block globs, even if they are not yet resolved, so that this kind of
1072 // self-inconsistent resolution never happens.
1073 // Re-enable the assert when the issue is fixed.
1074 // assert!(result[ns].get().is_err());
1081 let mut all_ns_failed
= true;
1082 self.r
.per_ns(|this
, ns
| {
1083 if !type_ns_only
|| ns
== TypeNS
{
1084 let binding
= this
.resolve_ident_in_module(
1088 &import
.parent_scope
,
1092 if binding
.is_ok() {
1093 all_ns_failed
= false;
1098 return if all_ns_failed
{
1099 let resolutions
= match module
{
1100 ModuleOrUniformRoot
::Module(module
) => {
1101 Some(self.r
.resolutions(module
).borrow())
1105 let resolutions
= resolutions
.as_ref().into_iter().flat_map(|r
| r
.iter());
1106 let names
= resolutions
1107 .filter_map(|(BindingKey { ident: i, .. }
, resolution
)| {
1110 } // Never suggest the same name
1111 match *resolution
.borrow() {
1112 NameResolution { binding: Some(name_binding), .. }
=> {
1113 match name_binding
.kind
{
1114 NameBindingKind
::Import { binding, .. }
=> {
1115 match binding
.kind
{
1116 // Never suggest the name that has binding error
1117 // i.e., the name that cannot be previously resolved
1118 NameBindingKind
::Res(Res
::Err
, _
) => None
,
1125 NameResolution { ref single_imports, .. }
1126 if single_imports
.is_empty() =>
1133 .collect
::<Vec
<Symbol
>>();
1135 let lev_suggestion
=
1136 find_best_match_for_name(&names
, ident
.name
, None
).map(|suggestion
| {
1138 vec
![(ident
.span
, suggestion
.to_string())],
1139 String
::from("a similar name exists in the module"),
1140 Applicability
::MaybeIncorrect
,
1144 let (suggestion
, note
) =
1145 match self.check_for_module_export_macro(import
, module
, ident
) {
1146 Some((suggestion
, note
)) => (suggestion
.or(lev_suggestion
), note
),
1147 _
=> (lev_suggestion
, Vec
::new()),
1150 let label
= match module
{
1151 ModuleOrUniformRoot
::Module(module
) => {
1152 let module_str
= module_to_string(module
);
1153 if let Some(module_str
) = module_str
{
1154 format
!("no `{}` in `{}`", ident
, module_str
)
1156 format
!("no `{}` in the root", ident
)
1160 if !ident
.is_path_segment_keyword() {
1161 format
!("no external crate `{}`", ident
)
1163 // HACK(eddyb) this shows up for `self` & `super`, which
1164 // should work instead - for now keep the same error message.
1165 format
!("no `{}` in the root", ident
)
1170 Some(UnresolvedImportError
{
1177 // `resolve_ident_in_module` reported a privacy error.
1178 self.r
.import_dummy_binding(import
);
1183 let mut reexport_error
= None
;
1184 let mut any_successful_reexport
= false;
1185 self.r
.per_ns(|this
, ns
| {
1186 if let Ok(binding
) = source_bindings
[ns
].get() {
1187 let vis
= import
.vis
.get();
1188 if !binding
.vis
.is_at_least(vis
, &*this
) {
1189 reexport_error
= Some((ns
, binding
));
1191 any_successful_reexport
= true;
1196 // All namespaces must be re-exported with extra visibility for an error to occur.
1197 if !any_successful_reexport
{
1198 let (ns
, binding
) = reexport_error
.unwrap();
1199 if pub_use_of_private_extern_crate_hack(import
, binding
) {
1201 "extern crate `{}` is private, and cannot be \
1202 re-exported (error E0365), consider declaring with \
1206 self.r
.lint_buffer
.buffer_lint(
1207 PUB_USE_OF_PRIVATE_EXTERN_CRATE
,
1212 } else if ns
== TypeNS
{
1217 "`{}` is private, and cannot be re-exported",
1220 .span_label(import
.span
, format
!("re-export of private `{}`", ident
))
1221 .note(&format
!("consider declaring type or module `{}` with `pub`", ident
))
1224 let msg
= format
!("`{}` is private, and cannot be re-exported", ident
);
1226 format
!("consider marking `{}` as `pub` in the imported module", ident
,);
1227 struct_span_err
!(self.r
.session
, import
.span
, E0364
, "{}", &msg
)
1228 .span_note(import
.span
, ¬e_msg
)
1233 if import
.module_path
.len() <= 1 {
1234 // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
1235 // 2 segments, so the `resolve_path` above won't trigger it.
1236 let mut full_path
= import
.module_path
.clone();
1237 full_path
.push(Segment
::from_ident(ident
));
1238 self.r
.per_ns(|this
, ns
| {
1239 if let Ok(binding
) = source_bindings
[ns
].get() {
1240 this
.lint_if_path_starts_with_module(
1241 import
.crate_lint(),
1250 // Record what this import resolves to for later uses in documentation,
1251 // this may resolve to either a value or a type, but for documentation
1252 // purposes it's good enough to just favor one over the other.
1253 self.r
.per_ns(|this
, ns
| {
1254 if let Ok(binding
) = source_bindings
[ns
].get() {
1255 this
.import_res_map
.entry(import
.id
).or_default()[ns
] = Some(binding
.res());
1259 self.check_for_redundant_imports(ident
, import
, source_bindings
, target_bindings
, target
);
1261 debug
!("(resolving single import) successfully resolved import");
1265 fn check_for_redundant_imports(
1268 import
: &'b Import
<'b
>,
1269 source_bindings
: &PerNS
<Cell
<Result
<&'b NameBinding
<'b
>, Determinacy
>>>,
1270 target_bindings
: &PerNS
<Cell
<Option
<&'b NameBinding
<'b
>>>>,
1273 // Skip if the import was produced by a macro.
1274 if import
.parent_scope
.expansion
!= LocalExpnId
::ROOT
{
1278 // Skip if we are inside a named module (in contrast to an anonymous
1279 // module defined by a block).
1280 if let ModuleKind
::Def(..) = import
.parent_scope
.module
.kind
{
1284 let mut is_redundant
= PerNS { value_ns: None, type_ns: None, macro_ns: None }
;
1286 let mut redundant_span
= PerNS { value_ns: None, type_ns: None, macro_ns: None }
;
1288 self.r
.per_ns(|this
, ns
| {
1289 if let Ok(binding
) = source_bindings
[ns
].get() {
1290 if binding
.res() == Res
::Err
{
1294 let orig_unusable_binding
=
1295 mem
::replace(&mut this
.unusable_binding
, target_bindings
[ns
].get());
1297 match this
.early_resolve_ident_in_lexical_scope(
1299 ScopeSet
::All(ns
, false),
1300 &import
.parent_scope
,
1305 Ok(other_binding
) => {
1306 is_redundant
[ns
] = Some(
1307 binding
.res() == other_binding
.res() && !other_binding
.is_ambiguity(),
1309 redundant_span
[ns
] = Some((other_binding
.span
, other_binding
.is_import()));
1311 Err(_
) => is_redundant
[ns
] = Some(false),
1314 this
.unusable_binding
= orig_unusable_binding
;
1318 if !is_redundant
.is_empty() && is_redundant
.present_items().all(|is_redundant
| is_redundant
)
1320 let mut redundant_spans
: Vec
<_
> = redundant_span
.present_items().collect();
1321 redundant_spans
.sort();
1322 redundant_spans
.dedup();
1323 self.r
.lint_buffer
.buffer_lint_with_diagnostic(
1327 &format
!("the item `{}` is imported redundantly", ident
),
1328 BuiltinLintDiagnostics
::RedundantImport(redundant_spans
, ident
),
1333 fn resolve_glob_import(&mut self, import
: &'b Import
<'b
>) {
1334 let module
= match import
.imported_module
.get().unwrap() {
1335 ModuleOrUniformRoot
::Module(module
) => module
,
1337 self.r
.session
.span_err(import
.span
, "cannot glob-import all possible crates");
1342 if module
.is_trait() {
1343 self.r
.session
.span_err(import
.span
, "items in traits are not importable.");
1345 } else if module
.def_id() == import
.parent_scope
.module
.def_id() {
1347 } else if let ImportKind
::Glob { is_prelude: true, .. }
= import
.kind
{
1348 self.r
.prelude
= Some(module
);
1352 // Add to module's glob_importers
1353 module
.glob_importers
.borrow_mut().push(import
);
1355 // Ensure that `resolutions` isn't borrowed during `try_define`,
1356 // since it might get updated via a glob cycle.
1359 .resolutions(module
)
1362 .filter_map(|(key
, resolution
)| {
1363 resolution
.borrow().binding().map(|binding
| (*key
, binding
))
1365 .collect
::<Vec
<_
>>();
1366 for (mut key
, binding
) in bindings
{
1367 let scope
= match key
.ident
.span
.reverse_glob_adjust(module
.expansion
, import
.span
) {
1368 Some(Some(def
)) => self.r
.macro_def_scope(def
),
1369 Some(None
) => import
.parent_scope
.module
,
1372 if self.r
.is_accessible_from(binding
.vis
, scope
) {
1373 let imported_binding
= self.r
.import(binding
, import
);
1374 let _
= self.r
.try_define(import
.parent_scope
.module
, key
, imported_binding
);
1378 // Record the destination of this import
1379 self.r
.record_partial_res(import
.id
, PartialRes
::new(module
.res().unwrap()));
1382 // Miscellaneous post-processing, including recording re-exports,
1383 // reporting conflicts, and reporting unresolved imports.
1384 fn finalize_resolutions_in(&mut self, module
: Module
<'b
>) {
1385 // Since import resolution is finished, globs will not define any more names.
1386 *module
.globs
.borrow_mut() = Vec
::new();
1388 let mut reexports
= Vec
::new();
1390 module
.for_each_child(self.r
, |this
, ident
, _
, binding
| {
1391 // Filter away ambiguous imports and anything that has def-site hygiene.
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 }
);
1403 if !reexports
.is_empty() {
1404 if let Some(def_id
) = module
.def_id() {
1405 // Call to `expect_local` should be fine because current
1406 // code is only called for local modules.
1407 self.r
.export_map
.insert(def_id
.expect_local(), reexports
);
1413 fn import_path_to_string(names
: &[Ident
], import_kind
: &ImportKind
<'_
>, span
: Span
) -> String
{
1414 let pos
= names
.iter().position(|p
| span
== p
.span
&& p
.name
!= kw
::PathRoot
);
1415 let global
= !names
.is_empty() && names
[0].name
== kw
::PathRoot
;
1416 if let Some(pos
) = pos
{
1417 let names
= if global { &names[1..pos + 1] }
else { &names[..pos + 1] }
;
1418 names_to_string(&names
.iter().map(|ident
| ident
.name
).collect
::<Vec
<_
>>())
1420 let names
= if global { &names[1..] }
else { names }
;
1421 if names
.is_empty() {
1422 import_kind_to_string(import_kind
)
1426 names_to_string(&names
.iter().map(|ident
| ident
.name
).collect
::<Vec
<_
>>()),
1427 import_kind_to_string(import_kind
),
1433 fn import_kind_to_string(import_kind
: &ImportKind
<'_
>) -> String
{
1435 ImportKind
::Single { source, .. }
=> source
.to_string(),
1436 ImportKind
::Glob { .. }
=> "*".to_string(),
1437 ImportKind
::ExternCrate { .. }
=> "<extern crate>".to_string(),
1438 ImportKind
::MacroUse
=> "#[macro_use]".to_string(),