1 // ignore-tidy-filelength
3 //! This crate is responsible for the part of name resolution that doesn't require type checker.
5 //! Module structure of the crate is built here.
6 //! Paths in macros, imports, expressions, types, patterns are resolved here.
7 //! Label and lifetime names are resolved here as well.
9 //! Type-relative name resolution (methods, fields, associated items) happens in `rustc_typeck`.
11 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
12 #![feature(box_patterns)]
13 #![feature(drain_filter)]
14 #![feature(bool_to_option)]
15 #![feature(crate_visibility_modifier)]
17 #![feature(never_type)]
19 #![recursion_limit = "256"]
20 #![allow(rustdoc::private_intra_doc_links)]
21 #![allow(rustc::potential_query_instability)]
26 pub use rustc_hir::def::{Namespace, PerNS};
30 use rustc_arena::{DroplessArena, TypedArena};
31 use rustc_ast::node_id::NodeMap;
32 use rustc_ast::ptr::P;
33 use rustc_ast::visit::{self, Visitor};
34 use rustc_ast::{self as ast, NodeId};
35 use rustc_ast::{Crate, CRATE_NODE_ID};
36 use rustc_ast::{Expr, ExprKind, LitKind};
37 use rustc_ast::{ItemKind, ModKind, Path};
38 use rustc_ast_lowering::ResolverAstLowering;
39 use rustc_ast_pretty::pprust;
40 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
41 use rustc_data_structures::intern::Interned;
42 use rustc_data_structures::sync::Lrc;
44 struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
46 use rustc_expand::base::{DeriveResolutions, SyntaxExtension, SyntaxExtensionKind};
47 use rustc_hir::def::Namespace::*;
48 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
49 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefPathHash, LocalDefId};
50 use rustc_hir::def_id::{CRATE_DEF_ID, CRATE_DEF_INDEX, LOCAL_CRATE};
51 use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
52 use rustc_hir::TraitCandidate;
53 use rustc_index::vec::IndexVec;
54 use rustc_metadata::creader::{CStore, CrateLoader};
55 use rustc_middle::metadata::ModChild;
56 use rustc_middle::middle::privacy::AccessLevels;
57 use rustc_middle::span_bug;
58 use rustc_middle::ty::query::Providers;
59 use rustc_middle::ty::{self, DefIdTree, MainDefinition, RegisteredTools, ResolverOutputs};
60 use rustc_query_system::ich::StableHashingContext;
61 use rustc_session::cstore::{CrateStore, MetadataLoaderDyn};
62 use rustc_session::lint;
63 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
64 use rustc_session::Session;
65 use rustc_span::edition::Edition;
66 use rustc_span::hygiene::{ExpnId, ExpnKind, LocalExpnId, MacroKind, SyntaxContext, Transparency};
67 use rustc_span::source_map::Spanned;
68 use rustc_span::symbol::{kw, sym, Ident, Symbol};
69 use rustc_span::{Span, DUMMY_SP};
71 use smallvec::{smallvec, SmallVec};
72 use std::cell::{Cell, RefCell};
73 use std::collections::BTreeSet;
74 use std::{cmp, fmt, iter, mem, ptr};
77 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
78 use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion};
79 use imports::{Import, ImportKind, ImportResolver, NameResolution};
80 use late::{ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind::*};
81 use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
83 use crate::access_levels::AccessLevelsVisitor;
85 type Res = def::Res<NodeId>;
88 mod build_reduced_graph;
101 #[derive(Copy, Clone, PartialEq, Debug)]
102 pub enum Determinacy {
108 fn determined(determined: bool) -> Determinacy {
109 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
113 /// A specific scope in which a name can be looked up.
114 /// This enum is currently used only for early resolution (imports and macros),
115 /// but not for late resolution yet.
116 #[derive(Clone, Copy)]
118 DeriveHelpers(LocalExpnId),
120 MacroRules(MacroRulesScopeRef<'a>),
122 // The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
123 // lint if it should be reported.
124 Module(Module<'a>, Option<NodeId>),
134 /// Names from different contexts may want to visit different subsets of all specific scopes
135 /// with different restrictions when looking up the resolution.
136 /// This enum is currently used only for early resolution (imports and macros),
137 /// but not for late resolution yet.
138 #[derive(Clone, Copy)]
140 /// All scopes with the given namespace.
141 All(Namespace, /*is_import*/ bool),
142 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
143 AbsolutePath(Namespace),
144 /// All scopes with macro namespace and the given macro kind restriction.
146 /// All scopes with the given namespace, used for partially performing late resolution.
147 /// The node id enables lints and is used for reporting them.
148 Late(Namespace, Module<'a>, Option<NodeId>),
151 /// Everything you need to know about a name's location to resolve it.
152 /// Serves as a starting point for the scope visitor.
153 /// This struct is currently used only for early resolution (imports and macros),
154 /// but not for late resolution yet.
155 #[derive(Clone, Copy, Debug)]
156 pub struct ParentScope<'a> {
158 expansion: LocalExpnId,
159 macro_rules: MacroRulesScopeRef<'a>,
160 derives: &'a [ast::Path],
163 impl<'a> ParentScope<'a> {
164 /// Creates a parent scope with the passed argument used as the module scope component,
165 /// and other scope components set to default empty values.
166 pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> {
169 expansion: LocalExpnId::ROOT,
170 macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty),
176 #[derive(Copy, Debug, Clone)]
177 enum ImplTraitContext {
179 Universal(LocalDefId),
183 struct BindingError {
185 origin: BTreeSet<Span>,
186 target: BTreeSet<Span>,
190 impl PartialOrd for BindingError {
191 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
192 Some(self.cmp(other))
196 impl PartialEq for BindingError {
197 fn eq(&self, other: &BindingError) -> bool {
198 self.name == other.name
202 impl Ord for BindingError {
203 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
204 self.name.cmp(&other.name)
208 enum ResolutionError<'a> {
209 /// Error E0401: can't use type or const parameters from outer function.
210 GenericParamsFromOuterFunction(Res, HasGenericParams),
211 /// Error E0403: the name is already used for a type or const parameter in this generic
213 NameAlreadyUsedInParameterList(Symbol, Span),
214 /// Error E0407: method is not a member of trait.
215 MethodNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
216 /// Error E0437: type is not a member of trait.
217 TypeNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
218 /// Error E0438: const is not a member of trait.
219 ConstNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
220 /// Error E0408: variable `{}` is not bound in all patterns.
221 VariableNotBoundInPattern(&'a BindingError),
222 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
223 VariableBoundWithDifferentMode(Symbol, Span),
224 /// Error E0415: identifier is bound more than once in this parameter list.
225 IdentifierBoundMoreThanOnceInParameterList(Symbol),
226 /// Error E0416: identifier is bound more than once in the same pattern.
227 IdentifierBoundMoreThanOnceInSamePattern(Symbol),
228 /// Error E0426: use of undeclared label.
229 UndeclaredLabel { name: Symbol, suggestion: Option<LabelSuggestion> },
230 /// Error E0429: `self` imports are only allowed within a `{ }` list.
231 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
232 /// Error E0430: `self` import can only appear once in the list.
233 SelfImportCanOnlyAppearOnceInTheList,
234 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
235 SelfImportOnlyInImportListWithNonEmptyPrefix,
236 /// Error E0433: failed to resolve.
237 FailedToResolve { label: String, suggestion: Option<Suggestion> },
238 /// Error E0434: can't capture dynamic environment in a fn item.
239 CannotCaptureDynamicEnvironmentInFnItem,
240 /// Error E0435: attempt to use a non-constant value in a constant.
241 AttemptToUseNonConstantValueInConstant(
243 /* suggestion */ &'static str,
244 /* current */ &'static str,
246 /// Error E0530: `X` bindings cannot shadow `Y`s.
247 BindingShadowsSomethingUnacceptable {
248 shadowing_binding_descr: &'static str,
250 participle: &'static str,
251 article: &'static str,
252 shadowed_binding_descr: &'static str,
253 shadowed_binding_span: Span,
255 /// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
256 ForwardDeclaredGenericParam,
257 /// ERROR E0770: the type of const parameters must not depend on other generic parameters.
258 ParamInTyOfConstParam(Symbol),
259 /// generic parameters must not be used inside const evaluations.
261 /// This error is only emitted when using `min_const_generics`.
262 ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
263 /// Error E0735: generic parameters with a default cannot use `Self`
264 SelfInGenericParamDefault,
265 /// Error E0767: use of unreachable label
266 UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
267 /// Error E0323, E0324, E0325: mismatch between trait item and impl item.
272 trait_item_span: Span,
273 code: rustc_errors::DiagnosticId,
277 enum VisResolutionError<'a> {
278 Relative2018(Span, &'a ast::Path),
280 FailedToResolve(Span, String, Option<Suggestion>),
281 ExpectedFound(Span, String, Res),
286 /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path
287 /// segments' which don't have the rest of an AST or HIR `PathSegment`.
288 #[derive(Clone, Copy, Debug)]
292 /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing
293 /// nonsensical suggestions.
294 has_generic_args: bool,
298 fn from_path(path: &Path) -> Vec<Segment> {
299 path.segments.iter().map(|s| s.into()).collect()
302 fn from_ident(ident: Ident) -> Segment {
303 Segment { ident, id: None, has_generic_args: false }
306 fn names_to_string(segments: &[Segment]) -> String {
307 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
311 impl<'a> From<&'a ast::PathSegment> for Segment {
312 fn from(seg: &'a ast::PathSegment) -> Segment {
313 Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() }
318 struct UsePlacementFinder {
319 target_module: NodeId,
320 first_legal_span: Option<Span>,
321 first_use_span: Option<Span>,
324 impl UsePlacementFinder {
325 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
327 UsePlacementFinder { target_module, first_legal_span: None, first_use_span: None };
328 finder.visit_crate(krate);
329 if let Some(use_span) = finder.first_use_span {
330 (Some(use_span), true)
332 (finder.first_legal_span, false)
337 fn is_span_suitable_for_use_injection(s: Span) -> bool {
338 // don't suggest placing a use before the prelude
339 // import or other generated ones
343 fn search_for_any_use_in_items(items: &[P<ast::Item>]) -> Option<Span> {
345 if let ItemKind::Use(..) = item.kind {
346 if is_span_suitable_for_use_injection(item.span) {
347 return Some(item.span.shrink_to_lo());
354 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
355 fn visit_crate(&mut self, c: &Crate) {
356 if self.target_module == CRATE_NODE_ID {
357 let inject = c.spans.inject_use_span;
358 if is_span_suitable_for_use_injection(inject) {
359 self.first_legal_span = Some(inject);
361 self.first_use_span = search_for_any_use_in_items(&c.items);
364 visit::walk_crate(self, c);
368 fn visit_item(&mut self, item: &'tcx ast::Item) {
369 if self.target_module == item.id {
370 if let ItemKind::Mod(_, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind {
371 let inject = mod_spans.inject_use_span;
372 if is_span_suitable_for_use_injection(inject) {
373 self.first_legal_span = Some(inject);
375 self.first_use_span = search_for_any_use_in_items(items);
379 visit::walk_item(self, item);
384 /// An intermediate resolution result.
386 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
387 /// items are visible in their whole block, while `Res`es only from the place they are defined
390 enum LexicalScopeBinding<'a> {
391 Item(&'a NameBinding<'a>),
395 impl<'a> LexicalScopeBinding<'a> {
396 fn res(self) -> Res {
398 LexicalScopeBinding::Item(binding) => binding.res(),
399 LexicalScopeBinding::Res(res) => res,
404 #[derive(Copy, Clone, Debug)]
405 enum ModuleOrUniformRoot<'a> {
409 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
410 CrateRootAndExternPrelude,
412 /// Virtual module that denotes resolution in extern prelude.
413 /// Used for paths starting with `::` on 2018 edition.
416 /// Virtual module that denotes resolution in current scope.
417 /// Used only for resolving single-segment imports. The reason it exists is that import paths
418 /// are always split into two parts, the first of which should be some kind of module.
422 impl ModuleOrUniformRoot<'_> {
423 fn same_def(lhs: Self, rhs: Self) -> bool {
425 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
429 ModuleOrUniformRoot::CrateRootAndExternPrelude,
430 ModuleOrUniformRoot::CrateRootAndExternPrelude,
432 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
433 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
439 #[derive(Clone, Debug)]
440 enum PathResult<'a> {
441 Module(ModuleOrUniformRoot<'a>),
442 NonModule(PartialRes),
447 suggestion: Option<Suggestion>,
448 is_error_from_last_segment: bool,
454 /// An anonymous module; e.g., just a block.
459 /// { // This is an anonymous module
460 /// f(); // This resolves to (2) as we are inside the block.
463 /// f(); // Resolves to (1)
467 /// Any module with a name.
471 /// * A normal module – either `mod from_file;` or `mod from_block { }` –
472 /// or the crate root (which is conceptually a top-level module).
473 /// Note that the crate root's [name][Self::name] will be [`kw::Empty`].
474 /// * A trait or an enum (it implicitly contains associated types, methods and variant
476 Def(DefKind, DefId, Symbol),
480 /// Get name of the module.
481 pub fn name(&self) -> Option<Symbol> {
483 ModuleKind::Block(..) => None,
484 ModuleKind::Def(.., name) => Some(*name),
489 /// A key that identifies a binding in a given `Module`.
491 /// Multiple bindings in the same module can have the same key (in a valid
492 /// program) if all but one of them come from glob imports.
493 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
495 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
499 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
500 /// `_` in the expanded AST that introduced this binding.
504 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
506 /// One node in the tree of modules.
508 /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these:
511 /// * crate root (aka, top-level anonymous module)
514 /// * curly-braced block with statements
516 /// You can use [`ModuleData::kind`] to determine the kind of module this is.
517 pub struct ModuleData<'a> {
518 /// The direct parent module (it may not be a `mod`, however).
519 parent: Option<Module<'a>>,
520 /// What kind of module this is, because this may not be a `mod`.
523 /// Mapping between names and their (possibly in-progress) resolutions in this module.
524 /// Resolutions in modules from other crates are not populated until accessed.
525 lazy_resolutions: Resolutions<'a>,
526 /// True if this is a module from other crate that needs to be populated on access.
527 populate_on_access: Cell<bool>,
529 /// Macro invocations that can expand into items in this module.
530 unexpanded_invocations: RefCell<FxHashSet<LocalExpnId>>,
532 /// Whether `#[no_implicit_prelude]` is active.
533 no_implicit_prelude: bool,
535 glob_importers: RefCell<Vec<&'a Import<'a>>>,
536 globs: RefCell<Vec<&'a Import<'a>>>,
538 /// Used to memoize the traits in this module for faster searches through all traits in scope.
539 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
541 /// Span of the module itself. Used for error reporting.
547 type Module<'a> = &'a ModuleData<'a>;
549 impl<'a> ModuleData<'a> {
551 parent: Option<Module<'a>>,
555 no_implicit_prelude: bool,
557 let is_foreign = match kind {
558 ModuleKind::Def(_, def_id, _) => !def_id.is_local(),
559 ModuleKind::Block(_) => false,
564 lazy_resolutions: Default::default(),
565 populate_on_access: Cell::new(is_foreign),
566 unexpanded_invocations: Default::default(),
568 glob_importers: RefCell::new(Vec::new()),
569 globs: RefCell::new(Vec::new()),
570 traits: RefCell::new(None),
576 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
578 R: AsMut<Resolver<'a>>,
579 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
581 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
582 if let Some(binding) = name_resolution.borrow().binding {
583 f(resolver, key.ident, key.ns, binding);
588 /// This modifies `self` in place. The traits will be stored in `self.traits`.
589 fn ensure_traits<R>(&'a self, resolver: &mut R)
591 R: AsMut<Resolver<'a>>,
593 let mut traits = self.traits.borrow_mut();
594 if traits.is_none() {
595 let mut collected_traits = Vec::new();
596 self.for_each_child(resolver, |_, name, ns, binding| {
600 if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() {
601 collected_traits.push((name, binding))
604 *traits = Some(collected_traits.into_boxed_slice());
608 fn res(&self) -> Option<Res> {
610 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
615 // Public for rustdoc.
616 pub fn def_id(&self) -> DefId {
617 self.opt_def_id().expect("`ModuleData::def_id` is called on a block module")
620 fn opt_def_id(&self) -> Option<DefId> {
622 ModuleKind::Def(_, def_id, _) => Some(def_id),
627 // `self` resolves to the first module ancestor that `is_normal`.
628 fn is_normal(&self) -> bool {
629 matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
632 fn is_trait(&self) -> bool {
633 matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
636 fn nearest_item_scope(&'a self) -> Module<'a> {
638 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
639 self.parent.expect("enum or trait module without a parent")
645 /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module).
646 /// This may be the crate root.
647 fn nearest_parent_mod(&self) -> DefId {
649 ModuleKind::Def(DefKind::Mod, def_id, _) => def_id,
650 _ => self.parent.expect("non-root module without parent").nearest_parent_mod(),
654 fn is_ancestor_of(&self, mut other: &Self) -> bool {
655 while !ptr::eq(self, other) {
656 if let Some(parent) = other.parent {
666 impl<'a> fmt::Debug for ModuleData<'a> {
667 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
668 write!(f, "{:?}", self.res())
672 /// Records a possibly-private value, type, or module definition.
673 #[derive(Clone, Debug)]
674 pub struct NameBinding<'a> {
675 kind: NameBindingKind<'a>,
676 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
677 expansion: LocalExpnId,
682 pub trait ToNameBinding<'a> {
683 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
686 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
687 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
692 #[derive(Clone, Debug)]
693 enum NameBindingKind<'a> {
694 Res(Res, /* is_macro_export */ bool),
696 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
699 impl<'a> NameBindingKind<'a> {
700 /// Is this a name binding of an import?
701 fn is_import(&self) -> bool {
702 matches!(*self, NameBindingKind::Import { .. })
706 struct PrivacyError<'a> {
708 binding: &'a NameBinding<'a>,
712 struct UseError<'a> {
713 err: DiagnosticBuilder<'a, ErrorGuaranteed>,
714 /// Candidates which user could `use` to access the missing type.
715 candidates: Vec<ImportSuggestion>,
716 /// The `DefId` of the module to place the use-statements in.
718 /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`).
720 /// Extra free-form suggestion.
721 suggestion: Option<(Span, &'static str, String, Applicability)>,
724 #[derive(Clone, Copy, PartialEq, Debug)]
729 MacroRulesVsModularized,
737 fn descr(self) -> &'static str {
739 AmbiguityKind::Import => "multiple potential import sources",
740 AmbiguityKind::BuiltinAttr => "a name conflict with a builtin attribute",
741 AmbiguityKind::DeriveHelper => "a name conflict with a derive helper attribute",
742 AmbiguityKind::MacroRulesVsModularized => {
743 "a conflict between a `macro_rules` name and a non-`macro_rules` name from another module"
745 AmbiguityKind::GlobVsOuter => {
746 "a conflict between a name from a glob import and an outer scope during import or macro resolution"
748 AmbiguityKind::GlobVsGlob => "multiple glob imports of a name in the same module",
749 AmbiguityKind::GlobVsExpanded => {
750 "a conflict between a name from a glob import and a macro-expanded name in the same module during import or macro resolution"
752 AmbiguityKind::MoreExpandedVsOuter => {
753 "a conflict between a macro-expanded name and a less macro-expanded name from outer scope during import or macro resolution"
759 /// Miscellaneous bits of metadata for better ambiguity error reporting.
760 #[derive(Clone, Copy, PartialEq)]
761 enum AmbiguityErrorMisc {
768 struct AmbiguityError<'a> {
771 b1: &'a NameBinding<'a>,
772 b2: &'a NameBinding<'a>,
773 misc1: AmbiguityErrorMisc,
774 misc2: AmbiguityErrorMisc,
777 impl<'a> NameBinding<'a> {
778 fn module(&self) -> Option<Module<'a>> {
780 NameBindingKind::Module(module) => Some(module),
781 NameBindingKind::Import { binding, .. } => binding.module(),
786 fn res(&self) -> Res {
788 NameBindingKind::Res(res, _) => res,
789 NameBindingKind::Module(module) => module.res().unwrap(),
790 NameBindingKind::Import { binding, .. } => binding.res(),
794 fn is_ambiguity(&self) -> bool {
795 self.ambiguity.is_some()
797 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
802 fn is_possibly_imported_variant(&self) -> bool {
804 NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
805 NameBindingKind::Res(
806 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
809 NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
813 fn is_extern_crate(&self) -> bool {
815 NameBindingKind::Import {
816 import: &Import { kind: ImportKind::ExternCrate { .. }, .. },
819 NameBindingKind::Module(&ModuleData {
820 kind: ModuleKind::Def(DefKind::Mod, def_id, _),
822 }) => def_id.index == CRATE_DEF_INDEX,
827 fn is_import(&self) -> bool {
828 matches!(self.kind, NameBindingKind::Import { .. })
831 fn is_glob_import(&self) -> bool {
833 NameBindingKind::Import { import, .. } => import.is_glob(),
838 fn is_importable(&self) -> bool {
841 Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
845 fn macro_kind(&self) -> Option<MacroKind> {
846 self.res().macro_kind()
849 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
850 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
851 // Then this function returns `true` if `self` may emerge from a macro *after* that
852 // in some later round and screw up our previously found resolution.
853 // See more detailed explanation in
854 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
857 invoc_parent_expansion: LocalExpnId,
858 binding: &NameBinding<'_>,
860 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
861 // Expansions are partially ordered, so "may appear after" is an inversion of
862 // "certainly appears before or simultaneously" and includes unordered cases.
863 let self_parent_expansion = self.expansion;
864 let other_parent_expansion = binding.expansion;
865 let certainly_before_other_or_simultaneously =
866 other_parent_expansion.is_descendant_of(self_parent_expansion);
867 let certainly_before_invoc_or_simultaneously =
868 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
869 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
873 #[derive(Debug, Default, Clone)]
874 pub struct ExternPreludeEntry<'a> {
875 extern_crate_item: Option<&'a NameBinding<'a>>,
876 pub introduced_by_item: bool,
879 /// Used for better errors for E0773
880 enum BuiltinMacroState {
881 NotYetSeen(SyntaxExtensionKind),
886 resolutions: DeriveResolutions,
887 helper_attrs: Vec<(usize, Ident)>,
888 has_derive_copy: bool,
891 /// The main resolver class.
893 /// This is the visitor that walks the whole crate.
894 pub struct Resolver<'a> {
895 session: &'a Session,
897 definitions: Definitions,
899 graph_root: Module<'a>,
901 prelude: Option<Module<'a>>,
902 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
904 /// N.B., this is used only for better diagnostics, not name resolution itself.
905 has_self: FxHashSet<DefId>,
907 /// Names of fields of an item `DefId` accessible with dot syntax.
908 /// Used for hints during error reporting.
909 field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>,
911 /// All imports known to succeed or fail.
912 determined_imports: Vec<&'a Import<'a>>,
914 /// All non-determined imports.
915 indeterminate_imports: Vec<&'a Import<'a>>,
917 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
918 /// We are resolving a last import segment during import validation.
919 last_import_segment: bool,
920 /// This binding should be ignored during in-module resolution, so that we don't get
921 /// "self-confirming" import resolutions during import validation.
922 unusable_binding: Option<&'a NameBinding<'a>>,
924 // Spans for local variables found during pattern resolution.
925 // Used for suggestions during error reporting.
926 pat_span_map: NodeMap<Span>,
928 /// Resolutions for nodes that have a single resolution.
929 partial_res_map: NodeMap<PartialRes>,
930 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
931 import_res_map: NodeMap<PerNS<Option<Res>>>,
932 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
933 label_res_map: NodeMap<NodeId>,
935 /// `CrateNum` resolutions of `extern crate` items.
936 extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
937 reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
938 trait_map: NodeMap<Vec<TraitCandidate>>,
940 /// A map from nodes to anonymous modules.
941 /// Anonymous modules are pseudo-modules that are implicitly created around items
942 /// contained within blocks.
944 /// For example, if we have this:
952 /// There will be an anonymous module created around `g` with the ID of the
953 /// entry block for `f`.
954 block_map: NodeMap<Module<'a>>,
955 /// A fake module that contains no definition and no prelude. Used so that
956 /// some AST passes can generate identifiers that only resolve to local or
958 empty_module: Module<'a>,
959 module_map: FxHashMap<DefId, Module<'a>>,
960 binding_parent_modules: FxHashMap<Interned<'a, NameBinding<'a>>, Module<'a>>,
961 underscore_disambiguator: u32,
963 /// Maps glob imports to the names of items actually imported.
964 glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
965 /// Visibilities in "lowered" form, for all entities that have them.
966 visibilities: FxHashMap<LocalDefId, ty::Visibility>,
967 used_imports: FxHashSet<NodeId>,
968 maybe_unused_trait_imports: FxHashSet<LocalDefId>,
969 maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
971 /// Privacy errors are delayed until the end in order to deduplicate them.
972 privacy_errors: Vec<PrivacyError<'a>>,
973 /// Ambiguity errors are delayed for deduplication.
974 ambiguity_errors: Vec<AmbiguityError<'a>>,
975 /// `use` injections are delayed for better placement and deduplication.
976 use_injections: Vec<UseError<'a>>,
977 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
978 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
980 arenas: &'a ResolverArenas<'a>,
981 dummy_binding: &'a NameBinding<'a>,
983 crate_loader: CrateLoader<'a>,
984 macro_names: FxHashSet<Ident>,
985 builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
986 /// A small map keeping true kinds of built-in macros that appear to be fn-like on
987 /// the surface (`macro` items in libcore), but are actually attributes or derives.
988 builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
989 registered_attrs: FxHashSet<Ident>,
990 registered_tools: RegisteredTools,
991 macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
992 all_macros: FxHashMap<Symbol, Res>,
993 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
994 dummy_ext_bang: Lrc<SyntaxExtension>,
995 dummy_ext_derive: Lrc<SyntaxExtension>,
996 non_macro_attr: Lrc<SyntaxExtension>,
997 local_macro_def_scopes: FxHashMap<LocalDefId, Module<'a>>,
998 ast_transform_scopes: FxHashMap<LocalExpnId, Module<'a>>,
999 unused_macros: FxHashMap<LocalDefId, (NodeId, Ident)>,
1000 proc_macro_stubs: FxHashSet<LocalDefId>,
1001 /// Traces collected during macro resolution and validated when it's complete.
1002 single_segment_macro_resolutions:
1003 Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>,
1004 multi_segment_macro_resolutions:
1005 Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>,
1006 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
1007 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
1008 /// Derive macros cannot modify the item themselves and have to store the markers in the global
1009 /// context, so they attach the markers to derive container IDs using this resolver table.
1010 containers_deriving_copy: FxHashSet<LocalExpnId>,
1011 /// Parent scopes in which the macros were invoked.
1012 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
1013 invocation_parent_scopes: FxHashMap<LocalExpnId, ParentScope<'a>>,
1014 /// `macro_rules` scopes *produced* by expanding the macro invocations,
1015 /// include all the `macro_rules` items and other invocations generated by them.
1016 output_macro_rules_scopes: FxHashMap<LocalExpnId, MacroRulesScopeRef<'a>>,
1017 /// Helper attributes that are in scope for the given expansion.
1018 helper_attrs: FxHashMap<LocalExpnId, Vec<Ident>>,
1019 /// Ready or in-progress results of resolving paths inside the `#[derive(...)]` attribute
1020 /// with the given `ExpnId`.
1021 derive_data: FxHashMap<LocalExpnId, DeriveData>,
1023 /// Avoid duplicated errors for "name already defined".
1024 name_already_seen: FxHashMap<Symbol, Span>,
1026 potentially_unused_imports: Vec<&'a Import<'a>>,
1028 /// Table for mapping struct IDs into struct constructor IDs,
1029 /// it's not used during normal resolution, only for better error reporting.
1030 /// Also includes of list of each fields visibility
1031 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
1033 /// Features enabled for this crate.
1034 active_features: FxHashSet<Symbol>,
1036 lint_buffer: LintBuffer,
1038 next_node_id: NodeId,
1040 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
1041 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
1043 /// Indices of unnamed struct or variant fields with unresolved attributes.
1044 placeholder_field_indices: FxHashMap<NodeId, usize>,
1045 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
1046 /// we know what parent node that fragment should be attached to thanks to this table,
1047 /// and how the `impl Trait` fragments were introduced.
1048 invocation_parents: FxHashMap<LocalExpnId, (LocalDefId, ImplTraitContext)>,
1050 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1051 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1052 /// FIXME: Replace with a more general AST map (together with some other fields).
1053 trait_impl_items: FxHashSet<LocalDefId>,
1055 legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
1056 /// Amount of lifetime parameters for each item in the crate.
1057 item_generics_num_lifetimes: FxHashMap<LocalDefId, usize>,
1059 main_def: Option<MainDefinition>,
1060 trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
1061 /// A list of proc macro LocalDefIds, written out in the order in which
1062 /// they are declared in the static array generated by proc_macro_harness.
1063 proc_macros: Vec<NodeId>,
1064 confused_type_with_std_module: FxHashMap<Span, Span>,
1066 access_levels: AccessLevels,
1069 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1071 pub struct ResolverArenas<'a> {
1072 modules: TypedArena<ModuleData<'a>>,
1073 local_modules: RefCell<Vec<Module<'a>>>,
1074 imports: TypedArena<Import<'a>>,
1075 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1076 ast_paths: TypedArena<ast::Path>,
1077 dropless: DroplessArena,
1080 impl<'a> ResolverArenas<'a> {
1083 parent: Option<Module<'a>>,
1087 no_implicit_prelude: bool,
1088 module_map: &mut FxHashMap<DefId, Module<'a>>,
1091 self.modules.alloc(ModuleData::new(parent, kind, expn_id, span, no_implicit_prelude));
1092 let def_id = module.opt_def_id();
1093 if def_id.map_or(true, |def_id| def_id.is_local()) {
1094 self.local_modules.borrow_mut().push(module);
1096 if let Some(def_id) = def_id {
1097 module_map.insert(def_id, module);
1101 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1102 self.local_modules.borrow()
1104 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1105 self.dropless.alloc(name_binding)
1107 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1108 self.imports.alloc(import)
1110 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1111 self.name_resolutions.alloc(Default::default())
1113 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1114 Interned::new_unchecked(self.dropless.alloc(Cell::new(scope)))
1116 fn alloc_macro_rules_binding(
1118 binding: MacroRulesBinding<'a>,
1119 ) -> &'a MacroRulesBinding<'a> {
1120 self.dropless.alloc(binding)
1122 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1123 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1125 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1126 self.dropless.alloc_from_iter(spans)
1130 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1131 fn as_mut(&mut self) -> &mut Resolver<'a> {
1136 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1137 fn parent(self, id: DefId) -> Option<DefId> {
1138 match id.as_local() {
1139 Some(id) => self.definitions.def_key(id).parent,
1140 None => self.cstore().def_key(id).parent,
1142 .map(|index| DefId { index, ..id })
1146 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1147 /// the resolver is no longer needed as all the relevant information is inline.
1148 impl ResolverAstLowering for Resolver<'_> {
1149 fn def_key(&mut self, id: DefId) -> DefKey {
1150 if let Some(id) = id.as_local() {
1151 self.definitions().def_key(id)
1153 self.cstore().def_key(id)
1158 fn def_span(&self, id: LocalDefId) -> Span {
1159 self.definitions.def_span(id)
1162 fn item_generics_num_lifetimes(&self, def_id: DefId) -> usize {
1163 if let Some(def_id) = def_id.as_local() {
1164 self.item_generics_num_lifetimes[&def_id]
1166 self.cstore().item_generics_num_lifetimes(def_id, self.session)
1170 fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
1171 self.legacy_const_generic_args(expr)
1174 fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
1175 self.partial_res_map.get(&id).cloned()
1178 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1179 self.import_res_map.get(&id).cloned().unwrap_or_default()
1182 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1183 self.label_res_map.get(&id).cloned()
1186 fn definitions(&mut self) -> &mut Definitions {
1187 &mut self.definitions
1190 fn create_stable_hashing_context(&self) -> StableHashingContext<'_> {
1191 StableHashingContext::new(self.session, &self.definitions, self.crate_loader.cstore())
1194 fn lint_buffer(&mut self) -> &mut LintBuffer {
1195 &mut self.lint_buffer
1198 fn next_node_id(&mut self) -> NodeId {
1202 fn take_trait_map(&mut self, node: NodeId) -> Option<Vec<TraitCandidate>> {
1203 self.trait_map.remove(&node)
1206 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1207 self.node_id_to_def_id.get(&node).copied()
1210 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1211 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1214 fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
1215 match def_id.as_local() {
1216 Some(def_id) => self.definitions.def_path_hash(def_id),
1217 None => self.cstore().def_path_hash(def_id),
1221 /// Adds a definition with a parent definition.
1225 node_id: ast::NodeId,
1231 !self.node_id_to_def_id.contains_key(&node_id),
1232 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1235 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1238 // Find the next free disambiguator for this key.
1239 let next_disambiguator = &mut self.next_disambiguator;
1240 let next_disambiguator = |parent, data| {
1241 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1242 let disambiguator = *next_disamb;
1243 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1247 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator, span);
1249 // Some things for which we allocate `LocalDefId`s don't correspond to
1250 // anything in the AST, so they don't have a `NodeId`. For these cases
1251 // we don't need a mapping from `NodeId` to `LocalDefId`.
1252 if node_id != ast::DUMMY_NODE_ID {
1253 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1254 self.node_id_to_def_id.insert(node_id, def_id);
1256 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1261 fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind {
1262 self.builtin_macro_kinds.get(&def_id).copied().unwrap_or(MacroKind::Bang)
1266 impl<'a> Resolver<'a> {
1268 session: &'a Session,
1271 metadata_loader: Box<MetadataLoaderDyn>,
1272 arenas: &'a ResolverArenas<'a>,
1274 let root_def_id = CRATE_DEF_ID.to_def_id();
1275 let mut module_map = FxHashMap::default();
1276 let graph_root = arenas.new_module(
1278 ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
1280 krate.spans.inner_span,
1281 session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1284 let empty_module = arenas.new_module(
1286 ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
1290 &mut FxHashMap::default(),
1293 let definitions = Definitions::new(session.local_stable_crate_id(), krate.spans.inner_span);
1294 let root = definitions.get_root_def();
1296 let mut visibilities = FxHashMap::default();
1297 visibilities.insert(CRATE_DEF_ID, ty::Visibility::Public);
1299 let mut def_id_to_node_id = IndexVec::default();
1300 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1301 let mut node_id_to_def_id = FxHashMap::default();
1302 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1304 let mut invocation_parents = FxHashMap::default();
1305 invocation_parents.insert(LocalExpnId::ROOT, (root, ImplTraitContext::Existential));
1307 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1311 .filter(|(_, entry)| entry.add_prelude)
1312 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1315 if !session.contains_name(&krate.attrs, sym::no_core) {
1316 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1317 if !session.contains_name(&krate.attrs, sym::no_std) {
1318 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1322 let (registered_attrs, registered_tools) =
1323 macros::registered_attrs_and_tools(session, &krate.attrs);
1325 let features = session.features_untracked();
1327 let mut resolver = Resolver {
1332 // The outermost module has def ID 0; this is not reflected in the
1338 has_self: FxHashSet::default(),
1339 field_names: FxHashMap::default(),
1341 determined_imports: Vec::new(),
1342 indeterminate_imports: Vec::new(),
1344 last_import_segment: false,
1345 unusable_binding: None,
1347 pat_span_map: Default::default(),
1348 partial_res_map: Default::default(),
1349 import_res_map: Default::default(),
1350 label_res_map: Default::default(),
1351 extern_crate_map: Default::default(),
1352 reexport_map: FxHashMap::default(),
1353 trait_map: NodeMap::default(),
1354 underscore_disambiguator: 0,
1357 block_map: Default::default(),
1358 binding_parent_modules: FxHashMap::default(),
1359 ast_transform_scopes: FxHashMap::default(),
1361 glob_map: Default::default(),
1363 used_imports: FxHashSet::default(),
1364 maybe_unused_trait_imports: Default::default(),
1365 maybe_unused_extern_crates: Vec::new(),
1367 privacy_errors: Vec::new(),
1368 ambiguity_errors: Vec::new(),
1369 use_injections: Vec::new(),
1370 macro_expanded_macro_export_errors: BTreeSet::new(),
1373 dummy_binding: arenas.alloc_name_binding(NameBinding {
1374 kind: NameBindingKind::Res(Res::Err, false),
1376 expansion: LocalExpnId::ROOT,
1378 vis: ty::Visibility::Public,
1381 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1382 macro_names: FxHashSet::default(),
1383 builtin_macros: Default::default(),
1384 builtin_macro_kinds: Default::default(),
1387 macro_use_prelude: FxHashMap::default(),
1388 all_macros: FxHashMap::default(),
1389 macro_map: FxHashMap::default(),
1390 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1391 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1392 non_macro_attr: Lrc::new(SyntaxExtension::non_macro_attr(session.edition())),
1393 invocation_parent_scopes: Default::default(),
1394 output_macro_rules_scopes: Default::default(),
1395 helper_attrs: Default::default(),
1396 derive_data: Default::default(),
1397 local_macro_def_scopes: FxHashMap::default(),
1398 name_already_seen: FxHashMap::default(),
1399 potentially_unused_imports: Vec::new(),
1400 struct_constructors: Default::default(),
1401 unused_macros: Default::default(),
1402 proc_macro_stubs: Default::default(),
1403 single_segment_macro_resolutions: Default::default(),
1404 multi_segment_macro_resolutions: Default::default(),
1405 builtin_attrs: Default::default(),
1406 containers_deriving_copy: Default::default(),
1407 active_features: features
1408 .declared_lib_features
1410 .map(|(feat, ..)| *feat)
1411 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1413 lint_buffer: LintBuffer::default(),
1414 next_node_id: CRATE_NODE_ID,
1417 placeholder_field_indices: Default::default(),
1419 next_disambiguator: Default::default(),
1420 trait_impl_items: Default::default(),
1421 legacy_const_generic_args: Default::default(),
1422 item_generics_num_lifetimes: Default::default(),
1423 main_def: Default::default(),
1424 trait_impls: Default::default(),
1425 proc_macros: Default::default(),
1426 confused_type_with_std_module: Default::default(),
1427 access_levels: Default::default(),
1430 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1431 resolver.invocation_parent_scopes.insert(LocalExpnId::ROOT, root_parent_scope);
1438 parent: Option<Module<'a>>,
1442 no_implicit_prelude: bool,
1444 let module_map = &mut self.module_map;
1445 self.arenas.new_module(parent, kind, expn_id, span, no_implicit_prelude, module_map)
1448 pub fn next_node_id(&mut self) -> NodeId {
1450 self.next_node_id.as_u32().checked_add(1).expect("input too large; ran out of NodeIds");
1451 mem::replace(&mut self.next_node_id, ast::NodeId::from_u32(next))
1454 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1455 &mut self.lint_buffer
1458 pub fn arenas() -> ResolverArenas<'a> {
1462 pub fn into_outputs(self) -> ResolverOutputs {
1463 let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
1464 let definitions = self.definitions;
1465 let visibilities = self.visibilities;
1466 let extern_crate_map = self.extern_crate_map;
1467 let reexport_map = self.reexport_map;
1468 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1469 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1470 let glob_map = self.glob_map;
1471 let main_def = self.main_def;
1472 let confused_type_with_std_module = self.confused_type_with_std_module;
1473 let access_levels = self.access_levels;
1476 cstore: Box::new(self.crate_loader.into_cstore()),
1482 maybe_unused_trait_imports,
1483 maybe_unused_extern_crates,
1484 extern_prelude: self
1487 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1490 trait_impls: self.trait_impls,
1492 confused_type_with_std_module,
1493 registered_tools: self.registered_tools,
1497 pub fn clone_outputs(&self) -> ResolverOutputs {
1498 let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
1500 definitions: self.definitions.clone(),
1501 access_levels: self.access_levels.clone(),
1502 cstore: Box::new(self.cstore().clone()),
1503 visibilities: self.visibilities.clone(),
1504 extern_crate_map: self.extern_crate_map.clone(),
1505 reexport_map: self.reexport_map.clone(),
1506 glob_map: self.glob_map.clone(),
1507 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1508 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1509 extern_prelude: self
1512 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1514 main_def: self.main_def,
1515 trait_impls: self.trait_impls.clone(),
1517 confused_type_with_std_module: self.confused_type_with_std_module.clone(),
1518 registered_tools: self.registered_tools.clone(),
1522 pub fn cstore(&self) -> &CStore {
1523 self.crate_loader.cstore()
1526 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1528 MacroKind::Bang => self.dummy_ext_bang.clone(),
1529 MacroKind::Derive => self.dummy_ext_derive.clone(),
1530 MacroKind::Attr => self.non_macro_attr.clone(),
1534 /// Runs the function on each namespace.
1535 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1541 fn is_builtin_macro(&mut self, res: Res) -> bool {
1542 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1545 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1547 match ctxt.outer_expn_data().macro_def_id {
1548 Some(def_id) => return def_id,
1549 None => ctxt.remove_mark(),
1554 /// Entry point to crate resolution.
1555 pub fn resolve_crate(&mut self, krate: &Crate) {
1556 self.session.time("resolve_crate", || {
1557 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1558 self.session.time("resolve_access_levels", || {
1559 AccessLevelsVisitor::compute_access_levels(self, krate)
1561 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1562 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1563 self.session.time("resolve_main", || self.resolve_main());
1564 self.session.time("resolve_check_unused", || self.check_unused(krate));
1565 self.session.time("resolve_report_errors", || self.report_errors(krate));
1566 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1570 pub fn traits_in_scope(
1572 current_trait: Option<Module<'a>>,
1573 parent_scope: &ParentScope<'a>,
1574 ctxt: SyntaxContext,
1575 assoc_item: Option<(Symbol, Namespace)>,
1576 ) -> Vec<TraitCandidate> {
1577 let mut found_traits = Vec::new();
1579 if let Some(module) = current_trait {
1580 if self.trait_may_have_item(Some(module), assoc_item) {
1581 let def_id = module.def_id();
1582 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1586 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1588 Scope::Module(module, _) => {
1589 this.traits_in_module(module, assoc_item, &mut found_traits);
1591 Scope::StdLibPrelude => {
1592 if let Some(module) = this.prelude {
1593 this.traits_in_module(module, assoc_item, &mut found_traits);
1596 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1597 _ => unreachable!(),
1605 fn traits_in_module(
1608 assoc_item: Option<(Symbol, Namespace)>,
1609 found_traits: &mut Vec<TraitCandidate>,
1611 module.ensure_traits(self);
1612 let traits = module.traits.borrow();
1613 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1614 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1615 let def_id = trait_binding.res().def_id();
1616 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1617 found_traits.push(TraitCandidate { def_id, import_ids });
1622 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1623 // associated item with the given name and namespace (if specified). This is a conservative
1624 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1625 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1626 // associated items.
1627 fn trait_may_have_item(
1629 trait_module: Option<Module<'a>>,
1630 assoc_item: Option<(Symbol, Namespace)>,
1632 match (trait_module, assoc_item) {
1633 (Some(trait_module), Some((name, ns))) => {
1634 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1635 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1636 assoc_ns == ns && assoc_ident.name == name
1643 fn find_transitive_imports(
1645 mut kind: &NameBindingKind<'_>,
1647 ) -> SmallVec<[LocalDefId; 1]> {
1648 let mut import_ids = smallvec![];
1649 while let NameBindingKind::Import { import, binding, .. } = kind {
1650 let id = self.local_def_id(import.id);
1651 self.maybe_unused_trait_imports.insert(id);
1652 self.add_to_glob_map(&import, trait_name);
1653 import_ids.push(id);
1654 kind = &binding.kind;
1659 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1660 let ident = ident.normalize_to_macros_2_0();
1661 let disambiguator = if ident.name == kw::Underscore {
1662 self.underscore_disambiguator += 1;
1663 self.underscore_disambiguator
1667 BindingKey { ident, ns, disambiguator }
1670 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1671 if module.populate_on_access.get() {
1672 module.populate_on_access.set(false);
1673 self.build_reduced_graph_external(module);
1675 &module.lazy_resolutions
1682 ) -> &'a RefCell<NameResolution<'a>> {
1684 .resolutions(module)
1687 .or_insert_with(|| self.arenas.alloc_name_resolution())
1693 used_binding: &'a NameBinding<'a>,
1694 is_lexical_scope: bool,
1696 if let Some((b2, kind)) = used_binding.ambiguity {
1697 self.ambiguity_errors.push(AmbiguityError {
1702 misc1: AmbiguityErrorMisc::None,
1703 misc2: AmbiguityErrorMisc::None,
1706 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1707 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1708 // but not introduce it, as used if they are accessed from lexical scope.
1709 if is_lexical_scope {
1710 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1711 if let Some(crate_item) = entry.extern_crate_item {
1712 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1719 import.used.set(true);
1720 self.used_imports.insert(import.id);
1721 self.add_to_glob_map(&import, ident);
1722 self.record_use(ident, binding, false);
1727 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1728 if import.is_glob() {
1729 let def_id = self.local_def_id(import.id);
1730 self.glob_map.entry(def_id).or_default().insert(ident.name);
1734 /// A generic scope visitor.
1735 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1736 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1739 scope_set: ScopeSet<'a>,
1740 parent_scope: &ParentScope<'a>,
1741 ctxt: SyntaxContext,
1742 mut visitor: impl FnMut(
1745 /*use_prelude*/ bool,
1749 // General principles:
1750 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1751 // built into the language or standard library. This way we can add new names into the
1752 // language or standard library without breaking user code.
1753 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1754 // Places to search (in order of decreasing priority):
1756 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1757 // (open set, not controlled).
1758 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1759 // (open, not controlled).
1760 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1761 // 4. Tool modules (closed, controlled right now, but not in the future).
1762 // 5. Standard library prelude (de-facto closed, controlled).
1763 // 6. Language prelude (closed, controlled).
1765 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1766 // (open set, not controlled).
1767 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1768 // (open, not controlled).
1769 // 3. Standard library prelude (de-facto closed, controlled).
1771 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1772 // are currently reported as errors. They should be higher in priority than preludes
1773 // and probably even names in modules according to the "general principles" above. They
1774 // also should be subject to restricted shadowing because are effectively produced by
1775 // derives (you need to resolve the derive first to add helpers into scope), but they
1776 // should be available before the derive is expanded for compatibility.
1777 // It's mess in general, so we are being conservative for now.
1778 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1779 // priority than prelude macros, but create ambiguities with macros in modules.
1780 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1781 // (open, not controlled). Have higher priority than prelude macros, but create
1782 // ambiguities with `macro_rules`.
1783 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1784 // 4a. User-defined prelude from macro-use
1785 // (open, the open part is from macro expansions, not controlled).
1786 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1787 // 4c. Standard library prelude (de-facto closed, controlled).
1788 // 6. Language prelude: builtin attributes (closed, controlled).
1790 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1791 let (ns, macro_kind, is_absolute_path) = match scope_set {
1792 ScopeSet::All(ns, _) => (ns, None, false),
1793 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1794 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1795 ScopeSet::Late(ns, ..) => (ns, None, false),
1797 let module = match scope_set {
1798 // Start with the specified module.
1799 ScopeSet::Late(_, module, _) => module,
1800 // Jump out of trait or enum modules, they do not act as scopes.
1801 _ => parent_scope.module.nearest_item_scope(),
1803 let mut scope = match ns {
1804 _ if is_absolute_path => Scope::CrateRoot,
1805 TypeNS | ValueNS => Scope::Module(module, None),
1806 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1808 let mut ctxt = ctxt.normalize_to_macros_2_0();
1809 let mut use_prelude = !module.no_implicit_prelude;
1812 let visit = match scope {
1813 // Derive helpers are not in scope when resolving derives in the same container.
1814 Scope::DeriveHelpers(expn_id) => {
1815 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1817 Scope::DeriveHelpersCompat => true,
1818 Scope::MacroRules(macro_rules_scope) => {
1819 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1820 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1821 // As another consequence of this optimization visitors never observe invocation
1822 // scopes for macros that were already expanded.
1823 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1824 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1825 macro_rules_scope.set(next_scope.get());
1832 Scope::CrateRoot => true,
1833 Scope::Module(..) => true,
1834 Scope::RegisteredAttrs => use_prelude,
1835 Scope::MacroUsePrelude => use_prelude || rust_2015,
1836 Scope::BuiltinAttrs => true,
1837 Scope::ExternPrelude => use_prelude || is_absolute_path,
1838 Scope::ToolPrelude => use_prelude,
1839 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1840 Scope::BuiltinTypes => true,
1844 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1845 return break_result;
1849 scope = match scope {
1850 Scope::DeriveHelpers(LocalExpnId::ROOT) => Scope::DeriveHelpersCompat,
1851 Scope::DeriveHelpers(expn_id) => {
1852 // Derive helpers are not visible to code generated by bang or derive macros.
1853 let expn_data = expn_id.expn_data();
1854 match expn_data.kind {
1856 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1857 Scope::DeriveHelpersCompat
1859 _ => Scope::DeriveHelpers(expn_data.parent.expect_local()),
1862 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1863 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1864 MacroRulesScope::Binding(binding) => {
1865 Scope::MacroRules(binding.parent_macro_rules_scope)
1867 MacroRulesScope::Invocation(invoc_id) => {
1868 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1870 MacroRulesScope::Empty => Scope::Module(module, None),
1872 Scope::CrateRoot => match ns {
1874 ctxt.adjust(ExpnId::root());
1875 Scope::ExternPrelude
1877 ValueNS | MacroNS => break,
1879 Scope::Module(module, prev_lint_id) => {
1880 use_prelude = !module.no_implicit_prelude;
1881 let derive_fallback_lint_id = match scope_set {
1882 ScopeSet::Late(.., lint_id) => lint_id,
1885 match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) {
1886 Some((parent_module, lint_id)) => {
1887 Scope::Module(parent_module, lint_id.or(prev_lint_id))
1890 ctxt.adjust(ExpnId::root());
1892 TypeNS => Scope::ExternPrelude,
1893 ValueNS => Scope::StdLibPrelude,
1894 MacroNS => Scope::RegisteredAttrs,
1899 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1900 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1901 Scope::BuiltinAttrs => break, // nowhere else to search
1902 Scope::ExternPrelude if is_absolute_path => break,
1903 Scope::ExternPrelude => Scope::ToolPrelude,
1904 Scope::ToolPrelude => Scope::StdLibPrelude,
1905 Scope::StdLibPrelude => match ns {
1906 TypeNS => Scope::BuiltinTypes,
1907 ValueNS => break, // nowhere else to search
1908 MacroNS => Scope::BuiltinAttrs,
1910 Scope::BuiltinTypes => break, // nowhere else to search
1917 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1918 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1919 /// `ident` in the first scope that defines it (or None if no scopes define it).
1921 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1922 /// the items are defined in the block. For example,
1925 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1928 /// g(); // This resolves to the local variable `g` since it shadows the item.
1932 /// Invariant: This must only be called during main resolution, not during
1933 /// import resolution.
1934 fn resolve_ident_in_lexical_scope(
1938 parent_scope: &ParentScope<'a>,
1939 record_used_id: Option<NodeId>,
1942 ) -> Option<LexicalScopeBinding<'a>> {
1943 assert!(ns == TypeNS || ns == ValueNS);
1944 let orig_ident = ident;
1945 if ident.name == kw::Empty {
1946 return Some(LexicalScopeBinding::Res(Res::Err));
1948 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1949 // FIXME(jseyfried) improve `Self` hygiene
1950 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1951 (empty_span, empty_span)
1952 } else if ns == TypeNS {
1953 let normalized_span = ident.span.normalize_to_macros_2_0();
1954 (normalized_span, normalized_span)
1956 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1958 ident.span = general_span;
1959 let normalized_ident = Ident { span: normalized_span, ..ident };
1961 // Walk backwards up the ribs in scope.
1962 let record_used = record_used_id.is_some();
1963 let mut module = self.graph_root;
1964 for i in (0..ribs.len()).rev() {
1965 debug!("walk rib\n{:?}", ribs[i].bindings);
1966 // Use the rib kind to determine whether we are resolving parameters
1967 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1968 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1969 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1971 // The ident resolves to a type parameter or local variable.
1972 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1978 *original_rib_ident_def,
1983 module = match ribs[i].kind {
1984 ModuleRibKind(module) => module,
1985 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1986 // If an invocation of this macro created `ident`, give up on `ident`
1987 // and switch to `ident`'s source from the macro definition.
1988 ident.span.remove_mark();
1995 ModuleKind::Block(..) => {} // We can see through blocks
1999 let item = self.resolve_ident_in_module_unadjusted(
2000 ModuleOrUniformRoot::Module(module),
2007 if let Ok(binding) = item {
2008 // The ident resolves to an item.
2009 return Some(LexicalScopeBinding::Item(binding));
2012 self.early_resolve_ident_in_lexical_scope(
2014 ScopeSet::Late(ns, module, record_used_id),
2021 .map(LexicalScopeBinding::Item)
2024 fn hygienic_lexical_parent(
2027 ctxt: &mut SyntaxContext,
2028 derive_fallback_lint_id: Option<NodeId>,
2029 ) -> Option<(Module<'a>, Option<NodeId>)> {
2030 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
2031 return Some((self.expn_def_scope(ctxt.remove_mark()), None));
2034 if let ModuleKind::Block(..) = module.kind {
2035 return Some((module.parent.unwrap().nearest_item_scope(), None));
2038 // We need to support the next case under a deprecation warning
2041 // ---- begin: this comes from a proc macro derive
2042 // mod implementation_details {
2043 // // Note that `MyStruct` is not in scope here.
2044 // impl SomeTrait for MyStruct { ... }
2048 // So we have to fall back to the module's parent during lexical resolution in this case.
2049 if derive_fallback_lint_id.is_some() {
2050 if let Some(parent) = module.parent {
2051 // Inner module is inside the macro, parent module is outside of the macro.
2052 if module.expansion != parent.expansion
2053 && module.expansion.is_descendant_of(parent.expansion)
2055 // The macro is a proc macro derive
2056 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
2057 let ext = self.get_macro_by_def_id(def_id);
2058 if ext.builtin_name.is_none()
2059 && ext.macro_kind() == MacroKind::Derive
2060 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
2062 return Some((parent, derive_fallback_lint_id));
2072 fn resolve_ident_in_module(
2074 module: ModuleOrUniformRoot<'a>,
2077 parent_scope: &ParentScope<'a>,
2080 ) -> Result<&'a NameBinding<'a>, Determinacy> {
2081 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
2082 .map_err(|(determinacy, _)| determinacy)
2085 fn resolve_ident_in_module_ext(
2087 module: ModuleOrUniformRoot<'a>,
2090 parent_scope: &ParentScope<'a>,
2093 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2094 let tmp_parent_scope;
2095 let mut adjusted_parent_scope = parent_scope;
2097 ModuleOrUniformRoot::Module(m) => {
2098 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2100 ParentScope { module: self.expn_def_scope(def), ..*parent_scope };
2101 adjusted_parent_scope = &tmp_parent_scope;
2104 ModuleOrUniformRoot::ExternPrelude => {
2105 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2107 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2111 self.resolve_ident_in_module_unadjusted_ext(
2115 adjusted_parent_scope,
2122 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2123 debug!("resolve_crate_root({:?})", ident);
2124 let mut ctxt = ident.span.ctxt();
2125 let mark = if ident.name == kw::DollarCrate {
2126 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2127 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2128 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2129 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2130 // definitions actually produced by `macro` and `macro` definitions produced by
2131 // `macro_rules!`, but at least such configurations are not stable yet.
2132 ctxt = ctxt.normalize_to_macro_rules();
2134 "resolve_crate_root: marks={:?}",
2135 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2137 let mut iter = ctxt.marks().into_iter().rev().peekable();
2138 let mut result = None;
2139 // Find the last opaque mark from the end if it exists.
2140 while let Some(&(mark, transparency)) = iter.peek() {
2141 if transparency == Transparency::Opaque {
2142 result = Some(mark);
2149 "resolve_crate_root: found opaque mark {:?} {:?}",
2151 result.map(|r| r.expn_data())
2153 // Then find the last semi-transparent mark from the end if it exists.
2154 for (mark, transparency) in iter {
2155 if transparency == Transparency::SemiTransparent {
2156 result = Some(mark);
2162 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2164 result.map(|r| r.expn_data())
2168 debug!("resolve_crate_root: not DollarCrate");
2169 ctxt = ctxt.normalize_to_macros_2_0();
2170 ctxt.adjust(ExpnId::root())
2172 let module = match mark {
2173 Some(def) => self.expn_def_scope(def),
2176 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2179 return self.graph_root;
2182 let module = self.expect_module(
2183 module.opt_def_id().map_or(LOCAL_CRATE, |def_id| def_id.krate).as_def_id(),
2186 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2195 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2196 let mut module = self.expect_module(module.nearest_parent_mod());
2197 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2198 let parent = module.parent.unwrap_or_else(|| self.expn_def_scope(ctxt.remove_mark()));
2199 module = self.expect_module(parent.nearest_parent_mod());
2207 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2208 parent_scope: &ParentScope<'a>,
2211 crate_lint: CrateLint,
2212 ) -> PathResult<'a> {
2213 self.resolve_path_with_ribs(
2224 fn resolve_path_with_ribs(
2227 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2228 parent_scope: &ParentScope<'a>,
2231 crate_lint: CrateLint,
2232 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2233 ) -> PathResult<'a> {
2234 let mut module = None;
2235 let mut allow_super = true;
2236 let mut second_binding = None;
2239 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2240 path_span={:?}, crate_lint={:?})",
2241 path, opt_ns, record_used, path_span, crate_lint,
2244 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2245 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2246 let record_segment_res = |this: &mut Self, res| {
2248 if let Some(id) = id {
2249 if !this.partial_res_map.contains_key(&id) {
2250 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2251 this.record_partial_res(id, PartialRes::new(res));
2257 let is_last = i == path.len() - 1;
2258 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2259 let name = ident.name;
2261 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2264 if allow_super && name == kw::Super {
2265 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2266 let self_module = match i {
2267 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2269 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2273 if let Some(self_module) = self_module {
2274 if let Some(parent) = self_module.parent {
2275 module = Some(ModuleOrUniformRoot::Module(
2276 self.resolve_self(&mut ctxt, parent),
2281 let msg = "there are too many leading `super` keywords".to_string();
2282 return PathResult::Failed {
2286 is_error_from_last_segment: false,
2290 if name == kw::SelfLower {
2291 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2292 module = Some(ModuleOrUniformRoot::Module(
2293 self.resolve_self(&mut ctxt, parent_scope.module),
2297 if name == kw::PathRoot && ident.span.rust_2018() {
2298 module = Some(ModuleOrUniformRoot::ExternPrelude);
2301 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2302 // `::a::b` from 2015 macro on 2018 global edition
2303 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2306 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2307 // `::a::b`, `crate::a::b` or `$crate::a::b`
2308 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2314 // Report special messages for path segment keywords in wrong positions.
2315 if ident.is_path_segment_keyword() && i != 0 {
2316 let name_str = if name == kw::PathRoot {
2317 "crate root".to_string()
2319 format!("`{}`", name)
2321 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2322 format!("global paths cannot start with {}", name_str)
2324 format!("{} in paths can only be used in start position", name_str)
2326 return PathResult::Failed {
2330 is_error_from_last_segment: false,
2334 enum FindBindingResult<'a> {
2335 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2336 PathResult(PathResult<'a>),
2338 let find_binding_in_ns = |this: &mut Self, ns| {
2339 let binding = if let Some(module) = module {
2340 this.resolve_ident_in_module(
2348 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2349 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2350 this.early_resolve_ident_in_lexical_scope(
2359 let record_used_id = if record_used {
2360 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2364 match this.resolve_ident_in_lexical_scope(
2372 // we found a locally-imported or available item/module
2373 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2374 // we found a local variable or type param
2375 Some(LexicalScopeBinding::Res(res))
2376 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2378 record_segment_res(this, res);
2379 return FindBindingResult::PathResult(PathResult::NonModule(
2380 PartialRes::with_unresolved_segments(res, path.len() - 1),
2383 _ => Err(Determinacy::determined(record_used)),
2386 FindBindingResult::Binding(binding)
2388 let binding = match find_binding_in_ns(self, ns) {
2389 FindBindingResult::PathResult(x) => return x,
2390 FindBindingResult::Binding(binding) => binding,
2395 second_binding = Some(binding);
2397 let res = binding.res();
2398 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2399 if let Some(next_module) = binding.module() {
2400 module = Some(ModuleOrUniformRoot::Module(next_module));
2401 record_segment_res(self, res);
2402 } else if res == Res::ToolMod && i + 1 != path.len() {
2403 if binding.is_import() {
2407 "cannot use a tool module through an import",
2409 .span_note(binding.span, "the tool module imported here")
2412 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2413 return PathResult::NonModule(PartialRes::new(res));
2414 } else if res == Res::Err {
2415 return PathResult::NonModule(PartialRes::new(Res::Err));
2416 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2417 self.lint_if_path_starts_with_module(
2423 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2428 let label = format!(
2429 "`{}` is {} {}, not a module",
2435 return PathResult::Failed {
2439 is_error_from_last_segment: is_last,
2443 Err(Undetermined) => return PathResult::Indeterminate,
2444 Err(Determined) => {
2445 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2446 if opt_ns.is_some() && !module.is_normal() {
2447 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2448 module.res().unwrap(),
2453 let module_res = match module {
2454 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2457 let (label, suggestion) = if module_res == self.graph_root.res() {
2458 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2459 // Don't look up import candidates if this is a speculative resolve
2460 let mut candidates = if record_used {
2461 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2465 candidates.sort_by_cached_key(|c| {
2466 (c.path.segments.len(), pprust::path_to_string(&c.path))
2468 if let Some(candidate) = candidates.get(0) {
2470 String::from("unresolved import"),
2472 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2473 String::from("a similar path exists"),
2474 Applicability::MaybeIncorrect,
2477 } else if self.session.edition() == Edition::Edition2015 {
2478 (format!("maybe a missing crate `{}`?", ident), None)
2480 (format!("could not find `{}` in the crate root", ident), None)
2488 .map_or(false, |c| c.is_ascii_uppercase())
2490 // Check whether the name refers to an item in the value namespace.
2491 let suggestion = if ribs.is_some() {
2492 let match_span = match self.resolve_ident_in_lexical_scope(
2498 &ribs.unwrap()[ValueNS],
2500 // Name matches a local variable. For example:
2503 // let Foo: &str = "";
2504 // println!("{}", Foo::Bar); // Name refers to local
2505 // // variable `Foo`.
2508 Some(LexicalScopeBinding::Res(Res::Local(id))) => {
2509 Some(*self.pat_span_map.get(&id).unwrap())
2512 // Name matches item from a local name binding
2513 // created by `use` declaration. For example:
2515 // pub Foo: &str = "";
2519 // println!("{}", Foo::Bar); // Name refers to local
2520 // // binding `Foo`.
2523 Some(LexicalScopeBinding::Item(name_binding)) => {
2524 Some(name_binding.span)
2529 if let Some(span) = match_span {
2531 vec![(span, String::from(""))],
2532 format!("`{}` is defined here, but is not a type", ident),
2533 Applicability::MaybeIncorrect,
2542 (format!("use of undeclared type `{}`", ident), suggestion)
2545 format!("use of undeclared crate or module `{}`", ident),
2546 if ident.name == sym::alloc {
2550 "add `extern crate alloc` to use the `alloc` crate",
2552 Applicability::MaybeIncorrect,
2555 self.find_similarly_named_module_or_crate(
2557 &parent_scope.module,
2561 vec![(ident.span, sugg.to_string())],
2563 "there is a crate or module with a similar name",
2565 Applicability::MaybeIncorrect,
2572 let parent = path[i - 1].ident.name;
2573 let parent = match parent {
2574 // ::foo is mounted at the crate root for 2015, and is the extern
2575 // prelude for 2018+
2576 kw::PathRoot if self.session.edition() > Edition::Edition2015 => {
2577 "the list of imported crates".to_owned()
2579 kw::PathRoot | kw::Crate => "the crate root".to_owned(),
2581 format!("`{}`", parent)
2585 let mut msg = format!("could not find `{}` in {}", ident, parent);
2586 if ns == TypeNS || ns == ValueNS {
2587 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2588 if let FindBindingResult::Binding(Ok(binding)) =
2589 find_binding_in_ns(self, ns_to_try)
2591 let mut found = |what| {
2593 "expected {}, found {} `{}` in {}",
2600 if binding.module().is_some() {
2603 match binding.res() {
2604 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2605 _ => found(ns_to_try.descr()),
2612 return PathResult::Failed {
2616 is_error_from_last_segment: is_last,
2622 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2624 PathResult::Module(match module {
2625 Some(module) => module,
2626 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2627 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2631 fn lint_if_path_starts_with_module(
2633 crate_lint: CrateLint,
2636 second_binding: Option<&NameBinding<'_>>,
2638 let (diag_id, diag_span) = match crate_lint {
2639 CrateLint::No => return,
2640 CrateLint::SimplePath(id) => (id, path_span),
2641 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2642 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2645 let first_name = match path.get(0) {
2646 // In the 2018 edition this lint is a hard error, so nothing to do
2647 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2651 // We're only interested in `use` paths which should start with
2652 // `{{root}}` currently.
2653 if first_name != kw::PathRoot {
2658 // If this import looks like `crate::...` it's already good
2659 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2660 // Otherwise go below to see if it's an extern crate
2662 // If the path has length one (and it's `PathRoot` most likely)
2663 // then we don't know whether we're gonna be importing a crate or an
2664 // item in our crate. Defer this lint to elsewhere
2668 // If the first element of our path was actually resolved to an
2669 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2670 // warning, this looks all good!
2671 if let Some(binding) = second_binding {
2672 if let NameBindingKind::Import { import, .. } = binding.kind {
2673 // Careful: we still want to rewrite paths from renamed extern crates.
2674 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2680 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2681 self.lint_buffer.buffer_lint_with_diagnostic(
2682 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2685 "absolute paths must start with `self`, `super`, \
2686 `crate`, or an external crate name in the 2018 edition",
2691 // Validate a local resolution (from ribs).
2692 fn validate_res_from_ribs(
2699 original_rib_ident_def: Ident,
2700 all_ribs: &[Rib<'a>],
2702 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2703 debug!("validate_res_from_ribs({:?})", res);
2704 let ribs = &all_ribs[rib_index + 1..];
2706 // An invalid forward use of a generic parameter from a previous default.
2707 if let ForwardGenericParamBanRibKind = all_ribs[rib_index].kind {
2709 let res_error = if rib_ident.name == kw::SelfUpper {
2710 ResolutionError::SelfInGenericParamDefault
2712 ResolutionError::ForwardDeclaredGenericParam
2714 self.report_error(span, res_error);
2716 assert_eq!(res, Res::Err);
2722 use ResolutionError::*;
2723 let mut res_err = None;
2728 | ClosureOrAsyncRibKind
2730 | MacroDefinition(..)
2731 | ForwardGenericParamBanRibKind => {
2732 // Nothing to do. Continue.
2734 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2735 // This was an attempt to access an upvar inside a
2736 // named function item. This is not allowed, so we
2739 // We don't immediately trigger a resolve error, because
2740 // we want certain other resolution errors (namely those
2741 // emitted for `ConstantItemRibKind` below) to take
2743 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2746 ConstantItemRibKind(_, item) => {
2747 // Still doesn't deal with upvars
2749 let (span, resolution_error) =
2750 if let Some((ident, constant_item_kind)) = item {
2751 let kind_str = match constant_item_kind {
2752 ConstantItemKind::Const => "const",
2753 ConstantItemKind::Static => "static",
2757 AttemptToUseNonConstantValueInConstant(
2758 ident, "let", kind_str,
2764 AttemptToUseNonConstantValueInConstant(
2765 original_rib_ident_def,
2771 self.report_error(span, resolution_error);
2775 ConstParamTyRibKind => {
2777 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2783 if let Some(res_err) = res_err {
2784 self.report_error(span, res_err);
2788 Res::Def(DefKind::TyParam, _) | Res::SelfTy { .. } => {
2790 let has_generic_params: HasGenericParams = match rib.kind {
2792 | ClosureOrAsyncRibKind
2795 | MacroDefinition(..)
2796 | ForwardGenericParamBanRibKind => {
2797 // Nothing to do. Continue.
2801 ConstantItemRibKind(trivial, _) => {
2802 let features = self.session.features_untracked();
2803 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2804 if !(trivial || features.generic_const_exprs) {
2805 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2806 // we can't easily tell if it's generic at this stage, so we instead remember
2807 // this and then enforce the self type to be concrete later on.
2808 if let Res::SelfTy { trait_, alias_to: Some((def, _)) } = res {
2809 res = Res::SelfTy { trait_, alias_to: Some((def, true)) }
2814 ResolutionError::ParamInNonTrivialAnonConst {
2815 name: rib_ident.name,
2821 self.session.delay_span_bug(span, CG_BUG_STR);
2829 // This was an attempt to use a type parameter outside its scope.
2830 ItemRibKind(has_generic_params) => has_generic_params,
2831 FnItemRibKind => HasGenericParams::Yes,
2832 ConstParamTyRibKind => {
2836 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2846 ResolutionError::GenericParamsFromOuterFunction(
2855 Res::Def(DefKind::ConstParam, _) => {
2856 let mut ribs = ribs.iter().peekable();
2857 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2858 // When declaring const parameters inside function signatures, the first rib
2859 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2860 // (spuriously) conflicting with the const param.
2865 let has_generic_params = match rib.kind {
2867 | ClosureOrAsyncRibKind
2870 | MacroDefinition(..)
2871 | ForwardGenericParamBanRibKind => continue,
2873 ConstantItemRibKind(trivial, _) => {
2874 let features = self.session.features_untracked();
2875 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2876 if !(trivial || features.generic_const_exprs) {
2880 ResolutionError::ParamInNonTrivialAnonConst {
2881 name: rib_ident.name,
2887 self.session.delay_span_bug(span, CG_BUG_STR);
2894 ItemRibKind(has_generic_params) => has_generic_params,
2895 FnItemRibKind => HasGenericParams::Yes,
2896 ConstParamTyRibKind => {
2900 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2907 // This was an attempt to use a const parameter outside its scope.
2911 ResolutionError::GenericParamsFromOuterFunction(
2925 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2926 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2927 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2928 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2932 fn record_pat_span(&mut self, node: NodeId, span: Span) {
2933 debug!("(recording pat) recording {:?} for {:?}", node, span);
2934 self.pat_span_map.insert(node, span);
2937 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2938 vis.is_accessible_from(module.nearest_parent_mod(), self)
2941 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2942 if let Some(old_module) =
2943 self.binding_parent_modules.insert(Interned::new_unchecked(binding), module)
2945 if !ptr::eq(module, old_module) {
2946 span_bug!(binding.span, "parent module is reset for binding");
2951 fn disambiguate_macro_rules_vs_modularized(
2953 macro_rules: &'a NameBinding<'a>,
2954 modularized: &'a NameBinding<'a>,
2956 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2957 // is disambiguated to mitigate regressions from macro modularization.
2958 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2960 self.binding_parent_modules.get(&Interned::new_unchecked(macro_rules)),
2961 self.binding_parent_modules.get(&Interned::new_unchecked(modularized)),
2963 (Some(macro_rules), Some(modularized)) => {
2964 macro_rules.nearest_parent_mod() == modularized.nearest_parent_mod()
2965 && modularized.is_ancestor_of(macro_rules)
2971 fn report_errors(&mut self, krate: &Crate) {
2972 self.report_with_use_injections(krate);
2974 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2975 let msg = "macro-expanded `macro_export` macros from the current crate \
2976 cannot be referred to by absolute paths";
2977 self.lint_buffer.buffer_lint_with_diagnostic(
2978 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2982 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2986 for ambiguity_error in &self.ambiguity_errors {
2987 self.report_ambiguity_error(ambiguity_error);
2990 let mut reported_spans = FxHashSet::default();
2991 for error in &self.privacy_errors {
2992 if reported_spans.insert(error.dedup_span) {
2993 self.report_privacy_error(error);
2998 fn report_with_use_injections(&mut self, krate: &Crate) {
2999 for UseError { mut err, candidates, def_id, instead, suggestion } in
3000 self.use_injections.drain(..)
3002 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
3003 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
3007 if !candidates.is_empty() {
3008 diagnostics::show_candidates(
3017 } else if let Some((span, msg, sugg, appl)) = suggestion {
3018 err.span_suggestion(span, msg, sugg, appl);
3024 fn report_conflict<'b>(
3029 new_binding: &NameBinding<'b>,
3030 old_binding: &NameBinding<'b>,
3032 // Error on the second of two conflicting names
3033 if old_binding.span.lo() > new_binding.span.lo() {
3034 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
3037 let container = match parent.kind {
3038 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()),
3039 ModuleKind::Block(..) => "block",
3042 let old_noun = match old_binding.is_import() {
3044 false => "definition",
3047 let new_participle = match new_binding.is_import() {
3053 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
3055 if let Some(s) = self.name_already_seen.get(&name) {
3061 let old_kind = match (ns, old_binding.module()) {
3062 (ValueNS, _) => "value",
3063 (MacroNS, _) => "macro",
3064 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
3065 (TypeNS, Some(module)) if module.is_normal() => "module",
3066 (TypeNS, Some(module)) if module.is_trait() => "trait",
3067 (TypeNS, _) => "type",
3070 let msg = format!("the name `{}` is defined multiple times", name);
3072 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
3073 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3074 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
3075 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3076 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3078 _ => match (old_binding.is_import(), new_binding.is_import()) {
3079 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3080 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3081 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3086 "`{}` must be defined only once in the {} namespace of this {}",
3092 err.span_label(span, format!("`{}` re{} here", name, new_participle));
3094 self.session.source_map().guess_head_span(old_binding.span),
3095 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
3098 // See https://github.com/rust-lang/rust/issues/32354
3099 use NameBindingKind::Import;
3100 let import = match (&new_binding.kind, &old_binding.kind) {
3101 // If there are two imports where one or both have attributes then prefer removing the
3102 // import without attributes.
3103 (Import { import: new, .. }, Import { import: old, .. })
3105 !new_binding.span.is_dummy()
3106 && !old_binding.span.is_dummy()
3107 && (new.has_attributes || old.has_attributes)
3110 if old.has_attributes {
3111 Some((new, new_binding.span, true))
3113 Some((old, old_binding.span, true))
3116 // Otherwise prioritize the new binding.
3117 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
3118 Some((import, new_binding.span, other.is_import()))
3120 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
3121 Some((import, old_binding.span, other.is_import()))
3126 // Check if the target of the use for both bindings is the same.
3127 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
3128 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
3130 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
3131 // Only suggest removing an import if both bindings are to the same def, if both spans
3132 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
3133 // been introduced by an item.
3134 let should_remove_import = duplicate
3136 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
3139 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3140 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3142 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3143 // Simple case - remove the entire import. Due to the above match arm, this can
3144 // only be a single use so just remove it entirely.
3145 err.tool_only_span_suggestion(
3146 import.use_span_with_attributes,
3147 "remove unnecessary import",
3149 Applicability::MaybeIncorrect,
3152 Some((import, span, _)) => {
3153 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3159 self.name_already_seen.insert(name, span);
3162 /// This function adds a suggestion to change the binding name of a new import that conflicts
3163 /// with an existing import.
3165 /// ```text,ignore (diagnostic)
3166 /// help: you can use `as` to change the binding name of the import
3168 /// LL | use foo::bar as other_bar;
3169 /// | ^^^^^^^^^^^^^^^^^^^^^
3171 fn add_suggestion_for_rename_of_use(
3173 err: &mut Diagnostic,
3175 import: &Import<'_>,
3178 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3179 format!("Other{}", name)
3181 format!("other_{}", name)
3184 let mut suggestion = None;
3186 ImportKind::Single { type_ns_only: true, .. } => {
3187 suggestion = Some(format!("self as {}", suggested_name))
3189 ImportKind::Single { source, .. } => {
3191 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3193 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3194 if pos <= snippet.len() {
3195 suggestion = Some(format!(
3199 if snippet.ends_with(';') { ";" } else { "" }
3205 ImportKind::ExternCrate { source, target } => {
3206 suggestion = Some(format!(
3207 "extern crate {} as {};",
3208 source.unwrap_or(target.name),
3212 _ => unreachable!(),
3215 let rename_msg = "you can use `as` to change the binding name of the import";
3216 if let Some(suggestion) = suggestion {
3217 err.span_suggestion(
3221 Applicability::MaybeIncorrect,
3224 err.span_label(binding_span, rename_msg);
3228 /// This function adds a suggestion to remove an unnecessary binding from an import that is
3229 /// nested. In the following example, this function will be invoked to remove the `a` binding
3230 /// in the second use statement:
3232 /// ```ignore (diagnostic)
3233 /// use issue_52891::a;
3234 /// use issue_52891::{d, a, e};
3237 /// The following suggestion will be added:
3239 /// ```ignore (diagnostic)
3240 /// use issue_52891::{d, a, e};
3241 /// ^-- help: remove unnecessary import
3244 /// If the nested use contains only one import then the suggestion will remove the entire
3247 /// It is expected that the provided import is nested - this isn't checked by the
3248 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3249 /// as characters expected by span manipulations won't be present.
3250 fn add_suggestion_for_duplicate_nested_use(
3252 err: &mut Diagnostic,
3253 import: &Import<'_>,
3256 assert!(import.is_nested());
3257 let message = "remove unnecessary import";
3259 // Two examples will be used to illustrate the span manipulations we're doing:
3261 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3262 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3263 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3264 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3266 let (found_closing_brace, span) =
3267 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3269 // If there was a closing brace then identify the span to remove any trailing commas from
3270 // previous imports.
3271 if found_closing_brace {
3272 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3273 err.tool_only_span_suggestion(
3277 Applicability::MaybeIncorrect,
3280 // Remove the entire line if we cannot extend the span back, this indicates an
3281 // `issue_52891::{self}` case.
3282 err.span_suggestion(
3283 import.use_span_with_attributes,
3286 Applicability::MaybeIncorrect,
3293 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3296 fn extern_prelude_get(
3300 ) -> Option<&'a NameBinding<'a>> {
3301 if ident.is_path_segment_keyword() {
3302 // Make sure `self`, `super` etc produce an error when passed to here.
3305 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3306 if let Some(binding) = entry.extern_crate_item {
3307 if !speculative && entry.introduced_by_item {
3308 self.record_use(ident, binding, false);
3312 let crate_id = if !speculative {
3313 let Some(crate_id) =
3314 self.crate_loader.process_path_extern(ident.name, ident.span) else { return Some(self.dummy_binding); };
3317 self.crate_loader.maybe_process_path_extern(ident.name)?
3319 let crate_root = self.expect_module(crate_id.as_def_id());
3321 (crate_root, ty::Visibility::Public, DUMMY_SP, LocalExpnId::ROOT)
3322 .to_name_binding(self.arenas),
3328 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3329 /// isn't something that can be returned because it can't be made to live that long,
3330 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3331 /// just that an error occurred.
3332 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3333 pub fn resolve_str_path_error(
3339 ) -> Result<(ast::Path, Res), ()> {
3340 let path = if path_str.starts_with("::") {
3343 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3344 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3345 .map(|i| self.new_ast_path_segment(i))
3354 .map(Ident::from_str)
3355 .map(|i| self.new_ast_path_segment(i))
3360 let module = self.expect_module(module_id);
3361 let parent_scope = &ParentScope::module(module, self);
3362 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3366 // Resolve a path passed from rustdoc or HIR lowering.
3367 fn resolve_ast_path(
3371 parent_scope: &ParentScope<'a>,
3372 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3373 match self.resolve_path(
3374 &Segment::from_path(path),
3381 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3382 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3383 Ok(path_res.base_res())
3385 PathResult::NonModule(..) => Err((
3387 ResolutionError::FailedToResolve {
3388 label: String::from("type-relative paths are not supported in this context"),
3392 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3393 PathResult::Failed { span, label, suggestion, .. } => {
3394 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3399 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3400 let mut seg = ast::PathSegment::from_ident(ident);
3401 seg.id = self.next_node_id();
3406 pub fn graph_root(&self) -> Module<'a> {
3411 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3416 /// For local modules returns only reexports, for external modules returns all children.
3417 pub fn module_children_or_reexports(&self, def_id: DefId) -> Vec<ModChild> {
3418 if let Some(def_id) = def_id.as_local() {
3419 self.reexport_map.get(&def_id).cloned().unwrap_or_default()
3421 self.cstore().module_children_untracked(def_id, self.session)
3425 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3427 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3428 def_id.as_local().map(|def_id| self.definitions.def_span(def_id))
3431 /// Checks if an expression refers to a function marked with
3432 /// `#[rustc_legacy_const_generics]` and returns the argument index list
3433 /// from the attribute.
3434 pub fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
3435 if let ExprKind::Path(None, path) = &expr.kind {
3436 // Don't perform legacy const generics rewriting if the path already
3437 // has generic arguments.
3438 if path.segments.last().unwrap().args.is_some() {
3442 let partial_res = self.partial_res_map.get(&expr.id)?;
3443 if partial_res.unresolved_segments() != 0 {
3447 if let Res::Def(def::DefKind::Fn, def_id) = partial_res.base_res() {
3448 // We only support cross-crate argument rewriting. Uses
3449 // within the same crate should be updated to use the new
3450 // const generics style.
3451 if def_id.is_local() {
3455 if let Some(v) = self.legacy_const_generic_args.get(&def_id) {
3461 .item_attrs_untracked(def_id, self.session)
3462 .find(|a| a.has_name(sym::rustc_legacy_const_generics))?;
3463 let mut ret = Vec::new();
3464 for meta in attr.meta_item_list()? {
3465 match meta.literal()?.kind {
3466 LitKind::Int(a, _) => ret.push(a as usize),
3467 _ => panic!("invalid arg index"),
3470 // Cache the lookup to avoid parsing attributes for an iterm multiple times.
3471 self.legacy_const_generic_args.insert(def_id, Some(ret.clone()));
3478 fn resolve_main(&mut self) {
3479 let module = self.graph_root;
3480 let ident = Ident::with_dummy_span(sym::main);
3481 let parent_scope = &ParentScope::module(module, self);
3483 let Ok(name_binding) = self.resolve_ident_in_module(
3484 ModuleOrUniformRoot::Module(module),
3494 let res = name_binding.res();
3495 let is_import = name_binding.is_import();
3496 let span = name_binding.span;
3497 if let Res::Def(DefKind::Fn, _) = res {
3498 self.record_use(ident, name_binding, false);
3500 self.main_def = Some(MainDefinition { res, is_import, span });
3504 fn names_to_string(names: &[Symbol]) -> String {
3505 let mut result = String::new();
3506 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3508 result.push_str("::");
3510 if Ident::with_dummy_span(*name).is_raw_guess() {
3511 result.push_str("r#");
3513 result.push_str(name.as_str());
3518 fn path_names_to_string(path: &Path) -> String {
3519 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3522 /// A somewhat inefficient routine to obtain the name of a module.
3523 fn module_to_string(module: Module<'_>) -> Option<String> {
3524 let mut names = Vec::new();
3526 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3527 if let ModuleKind::Def(.., name) = module.kind {
3528 if let Some(parent) = module.parent {
3530 collect_mod(names, parent);
3533 names.push(Symbol::intern("<opaque>"));
3534 collect_mod(names, module.parent.unwrap());
3537 collect_mod(&mut names, module);
3539 if names.is_empty() {
3543 Some(names_to_string(&names))
3546 #[derive(Copy, Clone, Debug)]
3548 /// Do not issue the lint.
3551 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3552 /// In this case, we can take the span of that path.
3555 /// This lint comes from a `use` statement. In this case, what we
3556 /// care about really is the *root* `use` statement; e.g., if we
3557 /// have nested things like `use a::{b, c}`, we care about the
3559 UsePath { root_id: NodeId, root_span: Span },
3561 /// This is the "trait item" from a fully qualified path. For example,
3562 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3563 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3564 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3568 fn node_id(&self) -> Option<NodeId> {
3570 CrateLint::No => None,
3571 CrateLint::SimplePath(id)
3572 | CrateLint::UsePath { root_id: id, .. }
3573 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3578 pub fn provide(providers: &mut Providers) {
3579 late::lifetimes::provide(providers);