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;
43 use rustc_errors::{struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorReported};
44 use rustc_expand::base::{DeriveResolutions, SyntaxExtension, SyntaxExtensionKind};
45 use rustc_hir::def::Namespace::*;
46 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
47 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefPathHash, LocalDefId};
48 use rustc_hir::def_id::{CRATE_DEF_ID, CRATE_DEF_INDEX, LOCAL_CRATE};
49 use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
50 use rustc_hir::TraitCandidate;
51 use rustc_index::vec::IndexVec;
52 use rustc_metadata::creader::{CStore, CrateLoader};
53 use rustc_middle::metadata::ModChild;
54 use rustc_middle::middle::privacy::AccessLevels;
55 use rustc_middle::span_bug;
56 use rustc_middle::ty::query::Providers;
57 use rustc_middle::ty::{self, DefIdTree, MainDefinition, RegisteredTools, ResolverOutputs};
58 use rustc_query_system::ich::StableHashingContext;
59 use rustc_session::cstore::{CrateStore, MetadataLoaderDyn};
60 use rustc_session::lint;
61 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
62 use rustc_session::Session;
63 use rustc_span::edition::Edition;
64 use rustc_span::hygiene::{ExpnId, ExpnKind, LocalExpnId, MacroKind, SyntaxContext, Transparency};
65 use rustc_span::source_map::Spanned;
66 use rustc_span::symbol::{kw, sym, Ident, Symbol};
67 use rustc_span::{Span, DUMMY_SP};
69 use smallvec::{smallvec, SmallVec};
70 use std::cell::{Cell, RefCell};
71 use std::collections::BTreeSet;
72 use std::ops::ControlFlow;
73 use std::{cmp, fmt, iter, mem, ptr};
76 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
77 use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion};
78 use imports::{Import, ImportKind, ImportResolver, NameResolution};
79 use late::{ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind::*};
80 use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
82 use crate::access_levels::AccessLevelsVisitor;
84 type Res = def::Res<NodeId>;
87 mod build_reduced_graph;
100 #[derive(Copy, Clone, PartialEq, Debug)]
101 pub enum Determinacy {
107 fn determined(determined: bool) -> Determinacy {
108 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
112 /// A specific scope in which a name can be looked up.
113 /// This enum is currently used only for early resolution (imports and macros),
114 /// but not for late resolution yet.
115 #[derive(Clone, Copy)]
117 DeriveHelpers(LocalExpnId),
119 MacroRules(MacroRulesScopeRef<'a>),
121 // The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
122 // lint if it should be reported.
123 Module(Module<'a>, Option<NodeId>),
133 /// Names from different contexts may want to visit different subsets of all specific scopes
134 /// with different restrictions when looking up the resolution.
135 /// This enum is currently used only for early resolution (imports and macros),
136 /// but not for late resolution yet.
137 #[derive(Clone, Copy)]
139 /// All scopes with the given namespace.
140 All(Namespace, /*is_import*/ bool),
141 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
142 AbsolutePath(Namespace),
143 /// All scopes with macro namespace and the given macro kind restriction.
145 /// All scopes with the given namespace, used for partially performing late resolution.
146 /// The node id enables lints and is used for reporting them.
147 Late(Namespace, Module<'a>, Option<NodeId>),
150 /// Everything you need to know about a name's location to resolve it.
151 /// Serves as a starting point for the scope visitor.
152 /// This struct is currently used only for early resolution (imports and macros),
153 /// but not for late resolution yet.
154 #[derive(Clone, Copy, Debug)]
155 pub struct ParentScope<'a> {
157 expansion: LocalExpnId,
158 macro_rules: MacroRulesScopeRef<'a>,
159 derives: &'a [ast::Path],
162 impl<'a> ParentScope<'a> {
163 /// Creates a parent scope with the passed argument used as the module scope component,
164 /// and other scope components set to default empty values.
165 pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> {
168 expansion: LocalExpnId::ROOT,
169 macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty),
175 #[derive(Copy, Debug, Clone)]
176 enum ImplTraitContext {
178 Universal(LocalDefId),
182 struct BindingError {
184 origin: BTreeSet<Span>,
185 target: BTreeSet<Span>,
189 impl PartialOrd for BindingError {
190 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
191 Some(self.cmp(other))
195 impl PartialEq for BindingError {
196 fn eq(&self, other: &BindingError) -> bool {
197 self.name == other.name
201 impl Ord for BindingError {
202 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
203 self.name.cmp(&other.name)
207 enum ResolutionError<'a> {
208 /// Error E0401: can't use type or const parameters from outer function.
209 GenericParamsFromOuterFunction(Res, HasGenericParams),
210 /// Error E0403: the name is already used for a type or const parameter in this generic
212 NameAlreadyUsedInParameterList(Symbol, Span),
213 /// Error E0407: method is not a member of trait.
214 MethodNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
215 /// Error E0437: type is not a member of trait.
216 TypeNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
217 /// Error E0438: const is not a member of trait.
218 ConstNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
219 /// Error E0408: variable `{}` is not bound in all patterns.
220 VariableNotBoundInPattern(&'a BindingError),
221 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
222 VariableBoundWithDifferentMode(Symbol, Span),
223 /// Error E0415: identifier is bound more than once in this parameter list.
224 IdentifierBoundMoreThanOnceInParameterList(Symbol),
225 /// Error E0416: identifier is bound more than once in the same pattern.
226 IdentifierBoundMoreThanOnceInSamePattern(Symbol),
227 /// Error E0426: use of undeclared label.
228 UndeclaredLabel { name: Symbol, suggestion: Option<LabelSuggestion> },
229 /// Error E0429: `self` imports are only allowed within a `{ }` list.
230 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
231 /// Error E0430: `self` import can only appear once in the list.
232 SelfImportCanOnlyAppearOnceInTheList,
233 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
234 SelfImportOnlyInImportListWithNonEmptyPrefix,
235 /// Error E0433: failed to resolve.
236 FailedToResolve { label: String, suggestion: Option<Suggestion> },
237 /// Error E0434: can't capture dynamic environment in a fn item.
238 CannotCaptureDynamicEnvironmentInFnItem,
239 /// Error E0435: attempt to use a non-constant value in a constant.
240 AttemptToUseNonConstantValueInConstant(
242 /* suggestion */ &'static str,
243 /* current */ &'static str,
245 /// Error E0530: `X` bindings cannot shadow `Y`s.
246 BindingShadowsSomethingUnacceptable {
247 shadowing_binding_descr: &'static str,
249 participle: &'static str,
250 article: &'static str,
251 shadowed_binding_descr: &'static str,
252 shadowed_binding_span: Span,
254 /// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
255 ForwardDeclaredGenericParam,
256 /// ERROR E0770: the type of const parameters must not depend on other generic parameters.
257 ParamInTyOfConstParam(Symbol),
258 /// generic parameters must not be used inside const evaluations.
260 /// This error is only emitted when using `min_const_generics`.
261 ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
262 /// Error E0735: generic parameters with a default cannot use `Self`
263 SelfInGenericParamDefault,
264 /// Error E0767: use of unreachable label
265 UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
266 /// Error E0323, E0324, E0325: mismatch between trait item and impl item.
271 trait_item_span: Span,
272 code: rustc_errors::DiagnosticId,
276 enum VisResolutionError<'a> {
277 Relative2018(Span, &'a ast::Path),
279 FailedToResolve(Span, String, Option<Suggestion>),
280 ExpectedFound(Span, String, Res),
285 /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path
286 /// segments' which don't have the rest of an AST or HIR `PathSegment`.
287 #[derive(Clone, Copy, Debug)]
291 /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing
292 /// nonsensical suggestions.
293 has_generic_args: bool,
297 fn from_path(path: &Path) -> Vec<Segment> {
298 path.segments.iter().map(|s| s.into()).collect()
301 fn from_ident(ident: Ident) -> Segment {
302 Segment { ident, id: None, has_generic_args: false }
305 fn names_to_string(segments: &[Segment]) -> String {
306 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
310 impl<'a> From<&'a ast::PathSegment> for Segment {
311 fn from(seg: &'a ast::PathSegment) -> Segment {
312 Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() }
316 struct UsePlacementFinder {
317 target_module: NodeId,
322 impl UsePlacementFinder {
323 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
324 let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
325 if let ControlFlow::Continue(..) = finder.check_mod(&krate.items, CRATE_NODE_ID) {
326 visit::walk_crate(&mut finder, krate);
328 (finder.span, finder.found_use)
331 fn check_mod(&mut self, items: &[P<ast::Item>], node_id: NodeId) -> ControlFlow<()> {
332 if self.span.is_some() {
333 return ControlFlow::Break(());
335 if node_id != self.target_module {
336 return ControlFlow::Continue(());
338 // find a use statement
341 ItemKind::Use(..) => {
342 // don't suggest placing a use before the prelude
343 // import or other generated ones
344 if !item.span.from_expansion() {
345 self.span = Some(item.span.shrink_to_lo());
346 self.found_use = true;
347 return ControlFlow::Break(());
350 // don't place use before extern crate
351 ItemKind::ExternCrate(_) => {}
352 // but place them before the first other item
354 if self.span.map_or(true, |span| item.span < span)
355 && !item.span.from_expansion()
357 self.span = Some(item.span.shrink_to_lo());
358 // don't insert between attributes and an item
359 // find the first attribute on the item
360 // FIXME: This is broken for active attributes.
361 for attr in &item.attrs {
362 if !attr.span.is_dummy()
363 && self.span.map_or(true, |span| attr.span < span)
365 self.span = Some(attr.span.shrink_to_lo());
372 ControlFlow::Continue(())
376 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
377 fn visit_item(&mut self, item: &'tcx ast::Item) {
378 if let ItemKind::Mod(_, ModKind::Loaded(items, ..)) = &item.kind {
379 if let ControlFlow::Break(..) = self.check_mod(items, item.id) {
383 visit::walk_item(self, item);
387 /// An intermediate resolution result.
389 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
390 /// items are visible in their whole block, while `Res`es only from the place they are defined
393 enum LexicalScopeBinding<'a> {
394 Item(&'a NameBinding<'a>),
398 impl<'a> LexicalScopeBinding<'a> {
399 fn res(self) -> Res {
401 LexicalScopeBinding::Item(binding) => binding.res(),
402 LexicalScopeBinding::Res(res) => res,
407 #[derive(Copy, Clone, Debug)]
408 enum ModuleOrUniformRoot<'a> {
412 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
413 CrateRootAndExternPrelude,
415 /// Virtual module that denotes resolution in extern prelude.
416 /// Used for paths starting with `::` on 2018 edition.
419 /// Virtual module that denotes resolution in current scope.
420 /// Used only for resolving single-segment imports. The reason it exists is that import paths
421 /// are always split into two parts, the first of which should be some kind of module.
425 impl ModuleOrUniformRoot<'_> {
426 fn same_def(lhs: Self, rhs: Self) -> bool {
428 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
432 ModuleOrUniformRoot::CrateRootAndExternPrelude,
433 ModuleOrUniformRoot::CrateRootAndExternPrelude,
435 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
436 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
442 #[derive(Clone, Debug)]
443 enum PathResult<'a> {
444 Module(ModuleOrUniformRoot<'a>),
445 NonModule(PartialRes),
450 suggestion: Option<Suggestion>,
451 is_error_from_last_segment: bool,
457 /// An anonymous module; e.g., just a block.
462 /// { // This is an anonymous module
463 /// f(); // This resolves to (2) as we are inside the block.
466 /// f(); // Resolves to (1)
470 /// Any module with a name.
474 /// * A normal module – either `mod from_file;` or `mod from_block { }` –
475 /// or the crate root (which is conceptually a top-level module).
476 /// Note that the crate root's [name][Self::name] will be [`kw::Empty`].
477 /// * A trait or an enum (it implicitly contains associated types, methods and variant
479 Def(DefKind, DefId, Symbol),
483 /// Get name of the module.
484 pub fn name(&self) -> Option<Symbol> {
486 ModuleKind::Block(..) => None,
487 ModuleKind::Def(.., name) => Some(*name),
492 /// A key that identifies a binding in a given `Module`.
494 /// Multiple bindings in the same module can have the same key (in a valid
495 /// program) if all but one of them come from glob imports.
496 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
498 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
502 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
503 /// `_` in the expanded AST that introduced this binding.
507 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
509 /// One node in the tree of modules.
511 /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these:
514 /// * crate root (aka, top-level anonymous module)
517 /// * curly-braced block with statements
519 /// You can use [`ModuleData::kind`] to determine the kind of module this is.
520 pub struct ModuleData<'a> {
521 /// The direct parent module (it may not be a `mod`, however).
522 parent: Option<Module<'a>>,
523 /// What kind of module this is, because this may not be a `mod`.
526 /// Mapping between names and their (possibly in-progress) resolutions in this module.
527 /// Resolutions in modules from other crates are not populated until accessed.
528 lazy_resolutions: Resolutions<'a>,
529 /// True if this is a module from other crate that needs to be populated on access.
530 populate_on_access: Cell<bool>,
532 /// Macro invocations that can expand into items in this module.
533 unexpanded_invocations: RefCell<FxHashSet<LocalExpnId>>,
535 /// Whether `#[no_implicit_prelude]` is active.
536 no_implicit_prelude: bool,
538 glob_importers: RefCell<Vec<&'a Import<'a>>>,
539 globs: RefCell<Vec<&'a Import<'a>>>,
541 /// Used to memoize the traits in this module for faster searches through all traits in scope.
542 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
544 /// Span of the module itself. Used for error reporting.
550 type Module<'a> = &'a ModuleData<'a>;
552 impl<'a> ModuleData<'a> {
554 parent: Option<Module<'a>>,
558 no_implicit_prelude: bool,
560 let is_foreign = match kind {
561 ModuleKind::Def(_, def_id, _) => !def_id.is_local(),
562 ModuleKind::Block(_) => false,
567 lazy_resolutions: Default::default(),
568 populate_on_access: Cell::new(is_foreign),
569 unexpanded_invocations: Default::default(),
571 glob_importers: RefCell::new(Vec::new()),
572 globs: RefCell::new(Vec::new()),
573 traits: RefCell::new(None),
579 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
581 R: AsMut<Resolver<'a>>,
582 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
584 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
585 if let Some(binding) = name_resolution.borrow().binding {
586 f(resolver, key.ident, key.ns, binding);
591 /// This modifies `self` in place. The traits will be stored in `self.traits`.
592 fn ensure_traits<R>(&'a self, resolver: &mut R)
594 R: AsMut<Resolver<'a>>,
596 let mut traits = self.traits.borrow_mut();
597 if traits.is_none() {
598 let mut collected_traits = Vec::new();
599 self.for_each_child(resolver, |_, name, ns, binding| {
603 if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() {
604 collected_traits.push((name, binding))
607 *traits = Some(collected_traits.into_boxed_slice());
611 fn res(&self) -> Option<Res> {
613 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
618 // Public for rustdoc.
619 pub fn def_id(&self) -> DefId {
620 self.opt_def_id().expect("`ModuleData::def_id` is called on a block module")
623 fn opt_def_id(&self) -> Option<DefId> {
625 ModuleKind::Def(_, def_id, _) => Some(def_id),
630 // `self` resolves to the first module ancestor that `is_normal`.
631 fn is_normal(&self) -> bool {
632 matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
635 fn is_trait(&self) -> bool {
636 matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
639 fn nearest_item_scope(&'a self) -> Module<'a> {
641 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
642 self.parent.expect("enum or trait module without a parent")
648 /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module).
649 /// This may be the crate root.
650 fn nearest_parent_mod(&self) -> DefId {
652 ModuleKind::Def(DefKind::Mod, def_id, _) => def_id,
653 _ => self.parent.expect("non-root module without parent").nearest_parent_mod(),
657 fn is_ancestor_of(&self, mut other: &Self) -> bool {
658 while !ptr::eq(self, other) {
659 if let Some(parent) = other.parent {
669 impl<'a> fmt::Debug for ModuleData<'a> {
670 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
671 write!(f, "{:?}", self.res())
675 /// Records a possibly-private value, type, or module definition.
676 #[derive(Clone, Debug)]
677 pub struct NameBinding<'a> {
678 kind: NameBindingKind<'a>,
679 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
680 expansion: LocalExpnId,
685 pub trait ToNameBinding<'a> {
686 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
689 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
690 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
695 #[derive(Clone, Debug)]
696 enum NameBindingKind<'a> {
697 Res(Res, /* is_macro_export */ bool),
699 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
702 impl<'a> NameBindingKind<'a> {
703 /// Is this a name binding of an import?
704 fn is_import(&self) -> bool {
705 matches!(*self, NameBindingKind::Import { .. })
709 struct PrivacyError<'a> {
711 binding: &'a NameBinding<'a>,
715 struct UseError<'a> {
716 err: DiagnosticBuilder<'a, ErrorReported>,
717 /// Candidates which user could `use` to access the missing type.
718 candidates: Vec<ImportSuggestion>,
719 /// The `DefId` of the module to place the use-statements in.
721 /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`).
723 /// Extra free-form suggestion.
724 suggestion: Option<(Span, &'static str, String, Applicability)>,
727 #[derive(Clone, Copy, PartialEq, Debug)]
732 MacroRulesVsModularized,
740 fn descr(self) -> &'static str {
742 AmbiguityKind::Import => "multiple potential import sources",
743 AmbiguityKind::BuiltinAttr => "a name conflict with a builtin attribute",
744 AmbiguityKind::DeriveHelper => "a name conflict with a derive helper attribute",
745 AmbiguityKind::MacroRulesVsModularized => {
746 "a conflict between a `macro_rules` name and a non-`macro_rules` name from another module"
748 AmbiguityKind::GlobVsOuter => {
749 "a conflict between a name from a glob import and an outer scope during import or macro resolution"
751 AmbiguityKind::GlobVsGlob => "multiple glob imports of a name in the same module",
752 AmbiguityKind::GlobVsExpanded => {
753 "a conflict between a name from a glob import and a macro-expanded name in the same module during import or macro resolution"
755 AmbiguityKind::MoreExpandedVsOuter => {
756 "a conflict between a macro-expanded name and a less macro-expanded name from outer scope during import or macro resolution"
762 /// Miscellaneous bits of metadata for better ambiguity error reporting.
763 #[derive(Clone, Copy, PartialEq)]
764 enum AmbiguityErrorMisc {
771 struct AmbiguityError<'a> {
774 b1: &'a NameBinding<'a>,
775 b2: &'a NameBinding<'a>,
776 misc1: AmbiguityErrorMisc,
777 misc2: AmbiguityErrorMisc,
780 impl<'a> NameBinding<'a> {
781 fn module(&self) -> Option<Module<'a>> {
783 NameBindingKind::Module(module) => Some(module),
784 NameBindingKind::Import { binding, .. } => binding.module(),
789 fn res(&self) -> Res {
791 NameBindingKind::Res(res, _) => res,
792 NameBindingKind::Module(module) => module.res().unwrap(),
793 NameBindingKind::Import { binding, .. } => binding.res(),
797 fn is_ambiguity(&self) -> bool {
798 self.ambiguity.is_some()
800 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
805 fn is_possibly_imported_variant(&self) -> bool {
807 NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
808 NameBindingKind::Res(
809 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
812 NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
816 fn is_extern_crate(&self) -> bool {
818 NameBindingKind::Import {
819 import: &Import { kind: ImportKind::ExternCrate { .. }, .. },
822 NameBindingKind::Module(&ModuleData {
823 kind: ModuleKind::Def(DefKind::Mod, def_id, _),
825 }) => def_id.index == CRATE_DEF_INDEX,
830 fn is_import(&self) -> bool {
831 matches!(self.kind, NameBindingKind::Import { .. })
834 fn is_glob_import(&self) -> bool {
836 NameBindingKind::Import { import, .. } => import.is_glob(),
841 fn is_importable(&self) -> bool {
844 Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
848 fn macro_kind(&self) -> Option<MacroKind> {
849 self.res().macro_kind()
852 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
853 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
854 // Then this function returns `true` if `self` may emerge from a macro *after* that
855 // in some later round and screw up our previously found resolution.
856 // See more detailed explanation in
857 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
860 invoc_parent_expansion: LocalExpnId,
861 binding: &NameBinding<'_>,
863 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
864 // Expansions are partially ordered, so "may appear after" is an inversion of
865 // "certainly appears before or simultaneously" and includes unordered cases.
866 let self_parent_expansion = self.expansion;
867 let other_parent_expansion = binding.expansion;
868 let certainly_before_other_or_simultaneously =
869 other_parent_expansion.is_descendant_of(self_parent_expansion);
870 let certainly_before_invoc_or_simultaneously =
871 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
872 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
876 #[derive(Debug, Default, Clone)]
877 pub struct ExternPreludeEntry<'a> {
878 extern_crate_item: Option<&'a NameBinding<'a>>,
879 pub introduced_by_item: bool,
882 /// Used for better errors for E0773
883 enum BuiltinMacroState {
884 NotYetSeen(SyntaxExtensionKind),
889 resolutions: DeriveResolutions,
890 helper_attrs: Vec<(usize, Ident)>,
891 has_derive_copy: bool,
894 /// The main resolver class.
896 /// This is the visitor that walks the whole crate.
897 pub struct Resolver<'a> {
898 session: &'a Session,
900 definitions: Definitions,
902 graph_root: Module<'a>,
904 prelude: Option<Module<'a>>,
905 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
907 /// N.B., this is used only for better diagnostics, not name resolution itself.
908 has_self: FxHashSet<DefId>,
910 /// Names of fields of an item `DefId` accessible with dot syntax.
911 /// Used for hints during error reporting.
912 field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>,
914 /// All imports known to succeed or fail.
915 determined_imports: Vec<&'a Import<'a>>,
917 /// All non-determined imports.
918 indeterminate_imports: Vec<&'a Import<'a>>,
920 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
921 /// We are resolving a last import segment during import validation.
922 last_import_segment: bool,
923 /// This binding should be ignored during in-module resolution, so that we don't get
924 /// "self-confirming" import resolutions during import validation.
925 unusable_binding: Option<&'a NameBinding<'a>>,
927 // Spans for local variables found during pattern resolution.
928 // Used for suggestions during error reporting.
929 pat_span_map: NodeMap<Span>,
931 /// Resolutions for nodes that have a single resolution.
932 partial_res_map: NodeMap<PartialRes>,
933 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
934 import_res_map: NodeMap<PerNS<Option<Res>>>,
935 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
936 label_res_map: NodeMap<NodeId>,
938 /// `CrateNum` resolutions of `extern crate` items.
939 extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
940 reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
941 trait_map: NodeMap<Vec<TraitCandidate>>,
943 /// A map from nodes to anonymous modules.
944 /// Anonymous modules are pseudo-modules that are implicitly created around items
945 /// contained within blocks.
947 /// For example, if we have this:
955 /// There will be an anonymous module created around `g` with the ID of the
956 /// entry block for `f`.
957 block_map: NodeMap<Module<'a>>,
958 /// A fake module that contains no definition and no prelude. Used so that
959 /// some AST passes can generate identifiers that only resolve to local or
961 empty_module: Module<'a>,
962 module_map: FxHashMap<DefId, Module<'a>>,
963 binding_parent_modules: FxHashMap<Interned<'a, NameBinding<'a>>, Module<'a>>,
964 underscore_disambiguator: u32,
966 /// Maps glob imports to the names of items actually imported.
967 glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
968 /// Visibilities in "lowered" form, for all entities that have them.
969 visibilities: FxHashMap<LocalDefId, ty::Visibility>,
970 used_imports: FxHashSet<NodeId>,
971 maybe_unused_trait_imports: FxHashSet<LocalDefId>,
972 maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
974 /// Privacy errors are delayed until the end in order to deduplicate them.
975 privacy_errors: Vec<PrivacyError<'a>>,
976 /// Ambiguity errors are delayed for deduplication.
977 ambiguity_errors: Vec<AmbiguityError<'a>>,
978 /// `use` injections are delayed for better placement and deduplication.
979 use_injections: Vec<UseError<'a>>,
980 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
981 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
983 arenas: &'a ResolverArenas<'a>,
984 dummy_binding: &'a NameBinding<'a>,
986 crate_loader: CrateLoader<'a>,
987 macro_names: FxHashSet<Ident>,
988 builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
989 /// A small map keeping true kinds of built-in macros that appear to be fn-like on
990 /// the surface (`macro` items in libcore), but are actually attributes or derives.
991 builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
992 registered_attrs: FxHashSet<Ident>,
993 registered_tools: RegisteredTools,
994 macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
995 all_macros: FxHashMap<Symbol, Res>,
996 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
997 dummy_ext_bang: Lrc<SyntaxExtension>,
998 dummy_ext_derive: Lrc<SyntaxExtension>,
999 non_macro_attr: Lrc<SyntaxExtension>,
1000 local_macro_def_scopes: FxHashMap<LocalDefId, Module<'a>>,
1001 ast_transform_scopes: FxHashMap<LocalExpnId, Module<'a>>,
1002 unused_macros: FxHashMap<LocalDefId, (NodeId, Ident)>,
1003 proc_macro_stubs: FxHashSet<LocalDefId>,
1004 /// Traces collected during macro resolution and validated when it's complete.
1005 single_segment_macro_resolutions:
1006 Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>,
1007 multi_segment_macro_resolutions:
1008 Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>,
1009 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
1010 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
1011 /// Derive macros cannot modify the item themselves and have to store the markers in the global
1012 /// context, so they attach the markers to derive container IDs using this resolver table.
1013 containers_deriving_copy: FxHashSet<LocalExpnId>,
1014 /// Parent scopes in which the macros were invoked.
1015 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
1016 invocation_parent_scopes: FxHashMap<LocalExpnId, ParentScope<'a>>,
1017 /// `macro_rules` scopes *produced* by expanding the macro invocations,
1018 /// include all the `macro_rules` items and other invocations generated by them.
1019 output_macro_rules_scopes: FxHashMap<LocalExpnId, MacroRulesScopeRef<'a>>,
1020 /// Helper attributes that are in scope for the given expansion.
1021 helper_attrs: FxHashMap<LocalExpnId, Vec<Ident>>,
1022 /// Ready or in-progress results of resolving paths inside the `#[derive(...)]` attribute
1023 /// with the given `ExpnId`.
1024 derive_data: FxHashMap<LocalExpnId, DeriveData>,
1026 /// Avoid duplicated errors for "name already defined".
1027 name_already_seen: FxHashMap<Symbol, Span>,
1029 potentially_unused_imports: Vec<&'a Import<'a>>,
1031 /// Table for mapping struct IDs into struct constructor IDs,
1032 /// it's not used during normal resolution, only for better error reporting.
1033 /// Also includes of list of each fields visibility
1034 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
1036 /// Features enabled for this crate.
1037 active_features: FxHashSet<Symbol>,
1039 lint_buffer: LintBuffer,
1041 next_node_id: NodeId,
1043 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
1044 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
1046 /// Indices of unnamed struct or variant fields with unresolved attributes.
1047 placeholder_field_indices: FxHashMap<NodeId, usize>,
1048 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
1049 /// we know what parent node that fragment should be attached to thanks to this table,
1050 /// and how the `impl Trait` fragments were introduced.
1051 invocation_parents: FxHashMap<LocalExpnId, (LocalDefId, ImplTraitContext)>,
1053 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1054 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1055 /// FIXME: Replace with a more general AST map (together with some other fields).
1056 trait_impl_items: FxHashSet<LocalDefId>,
1058 legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
1059 /// Amount of lifetime parameters for each item in the crate.
1060 item_generics_num_lifetimes: FxHashMap<LocalDefId, usize>,
1062 main_def: Option<MainDefinition>,
1063 trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
1064 /// A list of proc macro LocalDefIds, written out in the order in which
1065 /// they are declared in the static array generated by proc_macro_harness.
1066 proc_macros: Vec<NodeId>,
1067 confused_type_with_std_module: FxHashMap<Span, Span>,
1069 access_levels: AccessLevels,
1072 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1074 pub struct ResolverArenas<'a> {
1075 modules: TypedArena<ModuleData<'a>>,
1076 local_modules: RefCell<Vec<Module<'a>>>,
1077 imports: TypedArena<Import<'a>>,
1078 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1079 ast_paths: TypedArena<ast::Path>,
1080 dropless: DroplessArena,
1083 impl<'a> ResolverArenas<'a> {
1086 parent: Option<Module<'a>>,
1090 no_implicit_prelude: bool,
1091 module_map: &mut FxHashMap<DefId, Module<'a>>,
1094 self.modules.alloc(ModuleData::new(parent, kind, expn_id, span, no_implicit_prelude));
1095 let def_id = module.opt_def_id();
1096 if def_id.map_or(true, |def_id| def_id.is_local()) {
1097 self.local_modules.borrow_mut().push(module);
1099 if let Some(def_id) = def_id {
1100 module_map.insert(def_id, module);
1104 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1105 self.local_modules.borrow()
1107 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1108 self.dropless.alloc(name_binding)
1110 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1111 self.imports.alloc(import)
1113 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1114 self.name_resolutions.alloc(Default::default())
1116 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1117 Interned::new_unchecked(self.dropless.alloc(Cell::new(scope)))
1119 fn alloc_macro_rules_binding(
1121 binding: MacroRulesBinding<'a>,
1122 ) -> &'a MacroRulesBinding<'a> {
1123 self.dropless.alloc(binding)
1125 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1126 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1128 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1129 self.dropless.alloc_from_iter(spans)
1133 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1134 fn as_mut(&mut self) -> &mut Resolver<'a> {
1139 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1140 fn parent(self, id: DefId) -> Option<DefId> {
1141 match id.as_local() {
1142 Some(id) => self.definitions.def_key(id).parent,
1143 None => self.cstore().def_key(id).parent,
1145 .map(|index| DefId { index, ..id })
1149 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1150 /// the resolver is no longer needed as all the relevant information is inline.
1151 impl ResolverAstLowering for Resolver<'_> {
1152 fn def_key(&mut self, id: DefId) -> DefKey {
1153 if let Some(id) = id.as_local() {
1154 self.definitions().def_key(id)
1156 self.cstore().def_key(id)
1161 fn def_span(&self, id: LocalDefId) -> Span {
1162 self.definitions.def_span(id)
1165 fn item_generics_num_lifetimes(&self, def_id: DefId) -> usize {
1166 if let Some(def_id) = def_id.as_local() {
1167 self.item_generics_num_lifetimes[&def_id]
1169 self.cstore().item_generics_num_lifetimes(def_id, self.session)
1173 fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
1174 self.legacy_const_generic_args(expr)
1177 fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
1178 self.partial_res_map.get(&id).cloned()
1181 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1182 self.import_res_map.get(&id).cloned().unwrap_or_default()
1185 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1186 self.label_res_map.get(&id).cloned()
1189 fn definitions(&mut self) -> &mut Definitions {
1190 &mut self.definitions
1193 fn create_stable_hashing_context(&self) -> StableHashingContext<'_> {
1194 StableHashingContext::new(self.session, &self.definitions, self.crate_loader.cstore())
1197 fn lint_buffer(&mut self) -> &mut LintBuffer {
1198 &mut self.lint_buffer
1201 fn next_node_id(&mut self) -> NodeId {
1205 fn take_trait_map(&mut self, node: NodeId) -> Option<Vec<TraitCandidate>> {
1206 self.trait_map.remove(&node)
1209 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1210 self.node_id_to_def_id.get(&node).copied()
1213 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1214 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1217 fn def_path_hash(&self, def_id: DefId) -> DefPathHash {
1218 match def_id.as_local() {
1219 Some(def_id) => self.definitions.def_path_hash(def_id),
1220 None => self.cstore().def_path_hash(def_id),
1224 /// Adds a definition with a parent definition.
1228 node_id: ast::NodeId,
1234 !self.node_id_to_def_id.contains_key(&node_id),
1235 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1238 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1241 // Find the next free disambiguator for this key.
1242 let next_disambiguator = &mut self.next_disambiguator;
1243 let next_disambiguator = |parent, data| {
1244 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1245 let disambiguator = *next_disamb;
1246 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1250 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator, span);
1252 // Some things for which we allocate `LocalDefId`s don't correspond to
1253 // anything in the AST, so they don't have a `NodeId`. For these cases
1254 // we don't need a mapping from `NodeId` to `LocalDefId`.
1255 if node_id != ast::DUMMY_NODE_ID {
1256 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1257 self.node_id_to_def_id.insert(node_id, def_id);
1259 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1264 fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind {
1265 self.builtin_macro_kinds.get(&def_id).copied().unwrap_or(MacroKind::Bang)
1269 impl<'a> Resolver<'a> {
1271 session: &'a Session,
1274 metadata_loader: Box<MetadataLoaderDyn>,
1275 arenas: &'a ResolverArenas<'a>,
1277 let root_def_id = CRATE_DEF_ID.to_def_id();
1278 let mut module_map = FxHashMap::default();
1279 let graph_root = arenas.new_module(
1281 ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
1284 session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1287 let empty_module = arenas.new_module(
1289 ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
1293 &mut FxHashMap::default(),
1296 let definitions = Definitions::new(session.local_stable_crate_id(), krate.span);
1297 let root = definitions.get_root_def();
1299 let mut visibilities = FxHashMap::default();
1300 visibilities.insert(CRATE_DEF_ID, ty::Visibility::Public);
1302 let mut def_id_to_node_id = IndexVec::default();
1303 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1304 let mut node_id_to_def_id = FxHashMap::default();
1305 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1307 let mut invocation_parents = FxHashMap::default();
1308 invocation_parents.insert(LocalExpnId::ROOT, (root, ImplTraitContext::Existential));
1310 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1314 .filter(|(_, entry)| entry.add_prelude)
1315 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1318 if !session.contains_name(&krate.attrs, sym::no_core) {
1319 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1320 if !session.contains_name(&krate.attrs, sym::no_std) {
1321 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1325 let (registered_attrs, registered_tools) =
1326 macros::registered_attrs_and_tools(session, &krate.attrs);
1328 let features = session.features_untracked();
1330 let mut resolver = Resolver {
1335 // The outermost module has def ID 0; this is not reflected in the
1341 has_self: FxHashSet::default(),
1342 field_names: FxHashMap::default(),
1344 determined_imports: Vec::new(),
1345 indeterminate_imports: Vec::new(),
1347 last_import_segment: false,
1348 unusable_binding: None,
1350 pat_span_map: Default::default(),
1351 partial_res_map: Default::default(),
1352 import_res_map: Default::default(),
1353 label_res_map: Default::default(),
1354 extern_crate_map: Default::default(),
1355 reexport_map: FxHashMap::default(),
1356 trait_map: NodeMap::default(),
1357 underscore_disambiguator: 0,
1360 block_map: Default::default(),
1361 binding_parent_modules: FxHashMap::default(),
1362 ast_transform_scopes: FxHashMap::default(),
1364 glob_map: Default::default(),
1366 used_imports: FxHashSet::default(),
1367 maybe_unused_trait_imports: Default::default(),
1368 maybe_unused_extern_crates: Vec::new(),
1370 privacy_errors: Vec::new(),
1371 ambiguity_errors: Vec::new(),
1372 use_injections: Vec::new(),
1373 macro_expanded_macro_export_errors: BTreeSet::new(),
1376 dummy_binding: arenas.alloc_name_binding(NameBinding {
1377 kind: NameBindingKind::Res(Res::Err, false),
1379 expansion: LocalExpnId::ROOT,
1381 vis: ty::Visibility::Public,
1384 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1385 macro_names: FxHashSet::default(),
1386 builtin_macros: Default::default(),
1387 builtin_macro_kinds: Default::default(),
1390 macro_use_prelude: FxHashMap::default(),
1391 all_macros: FxHashMap::default(),
1392 macro_map: FxHashMap::default(),
1393 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1394 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1395 non_macro_attr: Lrc::new(SyntaxExtension::non_macro_attr(session.edition())),
1396 invocation_parent_scopes: Default::default(),
1397 output_macro_rules_scopes: Default::default(),
1398 helper_attrs: Default::default(),
1399 derive_data: Default::default(),
1400 local_macro_def_scopes: FxHashMap::default(),
1401 name_already_seen: FxHashMap::default(),
1402 potentially_unused_imports: Vec::new(),
1403 struct_constructors: Default::default(),
1404 unused_macros: Default::default(),
1405 proc_macro_stubs: Default::default(),
1406 single_segment_macro_resolutions: Default::default(),
1407 multi_segment_macro_resolutions: Default::default(),
1408 builtin_attrs: Default::default(),
1409 containers_deriving_copy: Default::default(),
1410 active_features: features
1411 .declared_lib_features
1413 .map(|(feat, ..)| *feat)
1414 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1416 lint_buffer: LintBuffer::default(),
1417 next_node_id: CRATE_NODE_ID,
1420 placeholder_field_indices: Default::default(),
1422 next_disambiguator: Default::default(),
1423 trait_impl_items: Default::default(),
1424 legacy_const_generic_args: Default::default(),
1425 item_generics_num_lifetimes: Default::default(),
1426 main_def: Default::default(),
1427 trait_impls: Default::default(),
1428 proc_macros: Default::default(),
1429 confused_type_with_std_module: Default::default(),
1430 access_levels: Default::default(),
1433 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1434 resolver.invocation_parent_scopes.insert(LocalExpnId::ROOT, root_parent_scope);
1441 parent: Option<Module<'a>>,
1445 no_implicit_prelude: bool,
1447 let module_map = &mut self.module_map;
1448 self.arenas.new_module(parent, kind, expn_id, span, no_implicit_prelude, module_map)
1451 pub fn next_node_id(&mut self) -> NodeId {
1453 self.next_node_id.as_u32().checked_add(1).expect("input too large; ran out of NodeIds");
1454 mem::replace(&mut self.next_node_id, ast::NodeId::from_u32(next))
1457 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1458 &mut self.lint_buffer
1461 pub fn arenas() -> ResolverArenas<'a> {
1465 pub fn into_outputs(self) -> ResolverOutputs {
1466 let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
1467 let definitions = self.definitions;
1468 let visibilities = self.visibilities;
1469 let extern_crate_map = self.extern_crate_map;
1470 let reexport_map = self.reexport_map;
1471 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1472 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1473 let glob_map = self.glob_map;
1474 let main_def = self.main_def;
1475 let confused_type_with_std_module = self.confused_type_with_std_module;
1476 let access_levels = self.access_levels;
1479 cstore: Box::new(self.crate_loader.into_cstore()),
1485 maybe_unused_trait_imports,
1486 maybe_unused_extern_crates,
1487 extern_prelude: self
1490 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1493 trait_impls: self.trait_impls,
1495 confused_type_with_std_module,
1496 registered_tools: self.registered_tools,
1500 pub fn clone_outputs(&self) -> ResolverOutputs {
1501 let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect();
1503 definitions: self.definitions.clone(),
1504 access_levels: self.access_levels.clone(),
1505 cstore: Box::new(self.cstore().clone()),
1506 visibilities: self.visibilities.clone(),
1507 extern_crate_map: self.extern_crate_map.clone(),
1508 reexport_map: self.reexport_map.clone(),
1509 glob_map: self.glob_map.clone(),
1510 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1511 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1512 extern_prelude: self
1515 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1517 main_def: self.main_def,
1518 trait_impls: self.trait_impls.clone(),
1520 confused_type_with_std_module: self.confused_type_with_std_module.clone(),
1521 registered_tools: self.registered_tools.clone(),
1525 pub fn cstore(&self) -> &CStore {
1526 self.crate_loader.cstore()
1529 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1531 MacroKind::Bang => self.dummy_ext_bang.clone(),
1532 MacroKind::Derive => self.dummy_ext_derive.clone(),
1533 MacroKind::Attr => self.non_macro_attr.clone(),
1537 /// Runs the function on each namespace.
1538 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1544 fn is_builtin_macro(&mut self, res: Res) -> bool {
1545 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1548 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1550 match ctxt.outer_expn_data().macro_def_id {
1551 Some(def_id) => return def_id,
1552 None => ctxt.remove_mark(),
1557 /// Entry point to crate resolution.
1558 pub fn resolve_crate(&mut self, krate: &Crate) {
1559 self.session.time("resolve_crate", || {
1560 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1561 self.session.time("resolve_access_levels", || {
1562 AccessLevelsVisitor::compute_access_levels(self, krate)
1564 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1565 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1566 self.session.time("resolve_main", || self.resolve_main());
1567 self.session.time("resolve_check_unused", || self.check_unused(krate));
1568 self.session.time("resolve_report_errors", || self.report_errors(krate));
1569 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1573 pub fn traits_in_scope(
1575 current_trait: Option<Module<'a>>,
1576 parent_scope: &ParentScope<'a>,
1577 ctxt: SyntaxContext,
1578 assoc_item: Option<(Symbol, Namespace)>,
1579 ) -> Vec<TraitCandidate> {
1580 let mut found_traits = Vec::new();
1582 if let Some(module) = current_trait {
1583 if self.trait_may_have_item(Some(module), assoc_item) {
1584 let def_id = module.def_id();
1585 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1589 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1591 Scope::Module(module, _) => {
1592 this.traits_in_module(module, assoc_item, &mut found_traits);
1594 Scope::StdLibPrelude => {
1595 if let Some(module) = this.prelude {
1596 this.traits_in_module(module, assoc_item, &mut found_traits);
1599 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1600 _ => unreachable!(),
1608 fn traits_in_module(
1611 assoc_item: Option<(Symbol, Namespace)>,
1612 found_traits: &mut Vec<TraitCandidate>,
1614 module.ensure_traits(self);
1615 let traits = module.traits.borrow();
1616 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1617 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1618 let def_id = trait_binding.res().def_id();
1619 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1620 found_traits.push(TraitCandidate { def_id, import_ids });
1625 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1626 // associated item with the given name and namespace (if specified). This is a conservative
1627 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1628 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1629 // associated items.
1630 fn trait_may_have_item(
1632 trait_module: Option<Module<'a>>,
1633 assoc_item: Option<(Symbol, Namespace)>,
1635 match (trait_module, assoc_item) {
1636 (Some(trait_module), Some((name, ns))) => {
1637 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1638 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1639 assoc_ns == ns && assoc_ident.name == name
1646 fn find_transitive_imports(
1648 mut kind: &NameBindingKind<'_>,
1650 ) -> SmallVec<[LocalDefId; 1]> {
1651 let mut import_ids = smallvec![];
1652 while let NameBindingKind::Import { import, binding, .. } = kind {
1653 let id = self.local_def_id(import.id);
1654 self.maybe_unused_trait_imports.insert(id);
1655 self.add_to_glob_map(&import, trait_name);
1656 import_ids.push(id);
1657 kind = &binding.kind;
1662 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1663 let ident = ident.normalize_to_macros_2_0();
1664 let disambiguator = if ident.name == kw::Underscore {
1665 self.underscore_disambiguator += 1;
1666 self.underscore_disambiguator
1670 BindingKey { ident, ns, disambiguator }
1673 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1674 if module.populate_on_access.get() {
1675 module.populate_on_access.set(false);
1676 self.build_reduced_graph_external(module);
1678 &module.lazy_resolutions
1685 ) -> &'a RefCell<NameResolution<'a>> {
1687 .resolutions(module)
1690 .or_insert_with(|| self.arenas.alloc_name_resolution())
1696 used_binding: &'a NameBinding<'a>,
1697 is_lexical_scope: bool,
1699 if let Some((b2, kind)) = used_binding.ambiguity {
1700 self.ambiguity_errors.push(AmbiguityError {
1705 misc1: AmbiguityErrorMisc::None,
1706 misc2: AmbiguityErrorMisc::None,
1709 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1710 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1711 // but not introduce it, as used if they are accessed from lexical scope.
1712 if is_lexical_scope {
1713 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1714 if let Some(crate_item) = entry.extern_crate_item {
1715 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1722 import.used.set(true);
1723 self.used_imports.insert(import.id);
1724 self.add_to_glob_map(&import, ident);
1725 self.record_use(ident, binding, false);
1730 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1731 if import.is_glob() {
1732 let def_id = self.local_def_id(import.id);
1733 self.glob_map.entry(def_id).or_default().insert(ident.name);
1737 /// A generic scope visitor.
1738 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1739 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1742 scope_set: ScopeSet<'a>,
1743 parent_scope: &ParentScope<'a>,
1744 ctxt: SyntaxContext,
1745 mut visitor: impl FnMut(
1748 /*use_prelude*/ bool,
1752 // General principles:
1753 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1754 // built into the language or standard library. This way we can add new names into the
1755 // language or standard library without breaking user code.
1756 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1757 // Places to search (in order of decreasing priority):
1759 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1760 // (open set, not controlled).
1761 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1762 // (open, not controlled).
1763 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1764 // 4. Tool modules (closed, controlled right now, but not in the future).
1765 // 5. Standard library prelude (de-facto closed, controlled).
1766 // 6. Language prelude (closed, controlled).
1768 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1769 // (open set, not controlled).
1770 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1771 // (open, not controlled).
1772 // 3. Standard library prelude (de-facto closed, controlled).
1774 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1775 // are currently reported as errors. They should be higher in priority than preludes
1776 // and probably even names in modules according to the "general principles" above. They
1777 // also should be subject to restricted shadowing because are effectively produced by
1778 // derives (you need to resolve the derive first to add helpers into scope), but they
1779 // should be available before the derive is expanded for compatibility.
1780 // It's mess in general, so we are being conservative for now.
1781 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1782 // priority than prelude macros, but create ambiguities with macros in modules.
1783 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1784 // (open, not controlled). Have higher priority than prelude macros, but create
1785 // ambiguities with `macro_rules`.
1786 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1787 // 4a. User-defined prelude from macro-use
1788 // (open, the open part is from macro expansions, not controlled).
1789 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1790 // 4c. Standard library prelude (de-facto closed, controlled).
1791 // 6. Language prelude: builtin attributes (closed, controlled).
1793 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1794 let (ns, macro_kind, is_absolute_path) = match scope_set {
1795 ScopeSet::All(ns, _) => (ns, None, false),
1796 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1797 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1798 ScopeSet::Late(ns, ..) => (ns, None, false),
1800 let module = match scope_set {
1801 // Start with the specified module.
1802 ScopeSet::Late(_, module, _) => module,
1803 // Jump out of trait or enum modules, they do not act as scopes.
1804 _ => parent_scope.module.nearest_item_scope(),
1806 let mut scope = match ns {
1807 _ if is_absolute_path => Scope::CrateRoot,
1808 TypeNS | ValueNS => Scope::Module(module, None),
1809 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1811 let mut ctxt = ctxt.normalize_to_macros_2_0();
1812 let mut use_prelude = !module.no_implicit_prelude;
1815 let visit = match scope {
1816 // Derive helpers are not in scope when resolving derives in the same container.
1817 Scope::DeriveHelpers(expn_id) => {
1818 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1820 Scope::DeriveHelpersCompat => true,
1821 Scope::MacroRules(macro_rules_scope) => {
1822 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1823 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1824 // As another consequence of this optimization visitors never observe invocation
1825 // scopes for macros that were already expanded.
1826 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1827 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1828 macro_rules_scope.set(next_scope.get());
1835 Scope::CrateRoot => true,
1836 Scope::Module(..) => true,
1837 Scope::RegisteredAttrs => use_prelude,
1838 Scope::MacroUsePrelude => use_prelude || rust_2015,
1839 Scope::BuiltinAttrs => true,
1840 Scope::ExternPrelude => use_prelude || is_absolute_path,
1841 Scope::ToolPrelude => use_prelude,
1842 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1843 Scope::BuiltinTypes => true,
1847 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1848 return break_result;
1852 scope = match scope {
1853 Scope::DeriveHelpers(LocalExpnId::ROOT) => Scope::DeriveHelpersCompat,
1854 Scope::DeriveHelpers(expn_id) => {
1855 // Derive helpers are not visible to code generated by bang or derive macros.
1856 let expn_data = expn_id.expn_data();
1857 match expn_data.kind {
1859 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1860 Scope::DeriveHelpersCompat
1862 _ => Scope::DeriveHelpers(expn_data.parent.expect_local()),
1865 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1866 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1867 MacroRulesScope::Binding(binding) => {
1868 Scope::MacroRules(binding.parent_macro_rules_scope)
1870 MacroRulesScope::Invocation(invoc_id) => {
1871 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1873 MacroRulesScope::Empty => Scope::Module(module, None),
1875 Scope::CrateRoot => match ns {
1877 ctxt.adjust(ExpnId::root());
1878 Scope::ExternPrelude
1880 ValueNS | MacroNS => break,
1882 Scope::Module(module, prev_lint_id) => {
1883 use_prelude = !module.no_implicit_prelude;
1884 let derive_fallback_lint_id = match scope_set {
1885 ScopeSet::Late(.., lint_id) => lint_id,
1888 match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) {
1889 Some((parent_module, lint_id)) => {
1890 Scope::Module(parent_module, lint_id.or(prev_lint_id))
1893 ctxt.adjust(ExpnId::root());
1895 TypeNS => Scope::ExternPrelude,
1896 ValueNS => Scope::StdLibPrelude,
1897 MacroNS => Scope::RegisteredAttrs,
1902 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1903 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1904 Scope::BuiltinAttrs => break, // nowhere else to search
1905 Scope::ExternPrelude if is_absolute_path => break,
1906 Scope::ExternPrelude => Scope::ToolPrelude,
1907 Scope::ToolPrelude => Scope::StdLibPrelude,
1908 Scope::StdLibPrelude => match ns {
1909 TypeNS => Scope::BuiltinTypes,
1910 ValueNS => break, // nowhere else to search
1911 MacroNS => Scope::BuiltinAttrs,
1913 Scope::BuiltinTypes => break, // nowhere else to search
1920 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1921 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1922 /// `ident` in the first scope that defines it (or None if no scopes define it).
1924 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1925 /// the items are defined in the block. For example,
1928 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1931 /// g(); // This resolves to the local variable `g` since it shadows the item.
1935 /// Invariant: This must only be called during main resolution, not during
1936 /// import resolution.
1937 fn resolve_ident_in_lexical_scope(
1941 parent_scope: &ParentScope<'a>,
1942 record_used_id: Option<NodeId>,
1945 ) -> Option<LexicalScopeBinding<'a>> {
1946 assert!(ns == TypeNS || ns == ValueNS);
1947 let orig_ident = ident;
1948 if ident.name == kw::Empty {
1949 return Some(LexicalScopeBinding::Res(Res::Err));
1951 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1952 // FIXME(jseyfried) improve `Self` hygiene
1953 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1954 (empty_span, empty_span)
1955 } else if ns == TypeNS {
1956 let normalized_span = ident.span.normalize_to_macros_2_0();
1957 (normalized_span, normalized_span)
1959 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1961 ident.span = general_span;
1962 let normalized_ident = Ident { span: normalized_span, ..ident };
1964 // Walk backwards up the ribs in scope.
1965 let record_used = record_used_id.is_some();
1966 let mut module = self.graph_root;
1967 for i in (0..ribs.len()).rev() {
1968 debug!("walk rib\n{:?}", ribs[i].bindings);
1969 // Use the rib kind to determine whether we are resolving parameters
1970 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1971 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1972 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1974 // The ident resolves to a type parameter or local variable.
1975 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1981 *original_rib_ident_def,
1986 module = match ribs[i].kind {
1987 ModuleRibKind(module) => module,
1988 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1989 // If an invocation of this macro created `ident`, give up on `ident`
1990 // and switch to `ident`'s source from the macro definition.
1991 ident.span.remove_mark();
1998 ModuleKind::Block(..) => {} // We can see through blocks
2002 let item = self.resolve_ident_in_module_unadjusted(
2003 ModuleOrUniformRoot::Module(module),
2010 if let Ok(binding) = item {
2011 // The ident resolves to an item.
2012 return Some(LexicalScopeBinding::Item(binding));
2015 self.early_resolve_ident_in_lexical_scope(
2017 ScopeSet::Late(ns, module, record_used_id),
2024 .map(LexicalScopeBinding::Item)
2027 fn hygienic_lexical_parent(
2030 ctxt: &mut SyntaxContext,
2031 derive_fallback_lint_id: Option<NodeId>,
2032 ) -> Option<(Module<'a>, Option<NodeId>)> {
2033 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
2034 return Some((self.expn_def_scope(ctxt.remove_mark()), None));
2037 if let ModuleKind::Block(..) = module.kind {
2038 return Some((module.parent.unwrap().nearest_item_scope(), None));
2041 // We need to support the next case under a deprecation warning
2044 // ---- begin: this comes from a proc macro derive
2045 // mod implementation_details {
2046 // // Note that `MyStruct` is not in scope here.
2047 // impl SomeTrait for MyStruct { ... }
2051 // So we have to fall back to the module's parent during lexical resolution in this case.
2052 if derive_fallback_lint_id.is_some() {
2053 if let Some(parent) = module.parent {
2054 // Inner module is inside the macro, parent module is outside of the macro.
2055 if module.expansion != parent.expansion
2056 && module.expansion.is_descendant_of(parent.expansion)
2058 // The macro is a proc macro derive
2059 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
2060 let ext = self.get_macro_by_def_id(def_id);
2061 if ext.builtin_name.is_none()
2062 && ext.macro_kind() == MacroKind::Derive
2063 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
2065 return Some((parent, derive_fallback_lint_id));
2075 fn resolve_ident_in_module(
2077 module: ModuleOrUniformRoot<'a>,
2080 parent_scope: &ParentScope<'a>,
2083 ) -> Result<&'a NameBinding<'a>, Determinacy> {
2084 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
2085 .map_err(|(determinacy, _)| determinacy)
2088 fn resolve_ident_in_module_ext(
2090 module: ModuleOrUniformRoot<'a>,
2093 parent_scope: &ParentScope<'a>,
2096 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2097 let tmp_parent_scope;
2098 let mut adjusted_parent_scope = parent_scope;
2100 ModuleOrUniformRoot::Module(m) => {
2101 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2103 ParentScope { module: self.expn_def_scope(def), ..*parent_scope };
2104 adjusted_parent_scope = &tmp_parent_scope;
2107 ModuleOrUniformRoot::ExternPrelude => {
2108 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2110 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2114 self.resolve_ident_in_module_unadjusted_ext(
2118 adjusted_parent_scope,
2125 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2126 debug!("resolve_crate_root({:?})", ident);
2127 let mut ctxt = ident.span.ctxt();
2128 let mark = if ident.name == kw::DollarCrate {
2129 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2130 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2131 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2132 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2133 // definitions actually produced by `macro` and `macro` definitions produced by
2134 // `macro_rules!`, but at least such configurations are not stable yet.
2135 ctxt = ctxt.normalize_to_macro_rules();
2137 "resolve_crate_root: marks={:?}",
2138 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2140 let mut iter = ctxt.marks().into_iter().rev().peekable();
2141 let mut result = None;
2142 // Find the last opaque mark from the end if it exists.
2143 while let Some(&(mark, transparency)) = iter.peek() {
2144 if transparency == Transparency::Opaque {
2145 result = Some(mark);
2152 "resolve_crate_root: found opaque mark {:?} {:?}",
2154 result.map(|r| r.expn_data())
2156 // Then find the last semi-transparent mark from the end if it exists.
2157 for (mark, transparency) in iter {
2158 if transparency == Transparency::SemiTransparent {
2159 result = Some(mark);
2165 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2167 result.map(|r| r.expn_data())
2171 debug!("resolve_crate_root: not DollarCrate");
2172 ctxt = ctxt.normalize_to_macros_2_0();
2173 ctxt.adjust(ExpnId::root())
2175 let module = match mark {
2176 Some(def) => self.expn_def_scope(def),
2179 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2182 return self.graph_root;
2185 let module = self.expect_module(
2186 module.opt_def_id().map_or(LOCAL_CRATE, |def_id| def_id.krate).as_def_id(),
2189 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2198 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2199 let mut module = self.expect_module(module.nearest_parent_mod());
2200 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2201 let parent = module.parent.unwrap_or_else(|| self.expn_def_scope(ctxt.remove_mark()));
2202 module = self.expect_module(parent.nearest_parent_mod());
2210 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2211 parent_scope: &ParentScope<'a>,
2214 crate_lint: CrateLint,
2215 ) -> PathResult<'a> {
2216 self.resolve_path_with_ribs(
2227 fn resolve_path_with_ribs(
2230 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2231 parent_scope: &ParentScope<'a>,
2234 crate_lint: CrateLint,
2235 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2236 ) -> PathResult<'a> {
2237 let mut module = None;
2238 let mut allow_super = true;
2239 let mut second_binding = None;
2242 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2243 path_span={:?}, crate_lint={:?})",
2244 path, opt_ns, record_used, path_span, crate_lint,
2247 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2248 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2249 let record_segment_res = |this: &mut Self, res| {
2251 if let Some(id) = id {
2252 if !this.partial_res_map.contains_key(&id) {
2253 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2254 this.record_partial_res(id, PartialRes::new(res));
2260 let is_last = i == path.len() - 1;
2261 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2262 let name = ident.name;
2264 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2267 if allow_super && name == kw::Super {
2268 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2269 let self_module = match i {
2270 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2272 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2276 if let Some(self_module) = self_module {
2277 if let Some(parent) = self_module.parent {
2278 module = Some(ModuleOrUniformRoot::Module(
2279 self.resolve_self(&mut ctxt, parent),
2284 let msg = "there are too many leading `super` keywords".to_string();
2285 return PathResult::Failed {
2289 is_error_from_last_segment: false,
2293 if name == kw::SelfLower {
2294 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2295 module = Some(ModuleOrUniformRoot::Module(
2296 self.resolve_self(&mut ctxt, parent_scope.module),
2300 if name == kw::PathRoot && ident.span.rust_2018() {
2301 module = Some(ModuleOrUniformRoot::ExternPrelude);
2304 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2305 // `::a::b` from 2015 macro on 2018 global edition
2306 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2309 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2310 // `::a::b`, `crate::a::b` or `$crate::a::b`
2311 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2317 // Report special messages for path segment keywords in wrong positions.
2318 if ident.is_path_segment_keyword() && i != 0 {
2319 let name_str = if name == kw::PathRoot {
2320 "crate root".to_string()
2322 format!("`{}`", name)
2324 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2325 format!("global paths cannot start with {}", name_str)
2327 format!("{} in paths can only be used in start position", name_str)
2329 return PathResult::Failed {
2333 is_error_from_last_segment: false,
2337 enum FindBindingResult<'a> {
2338 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2339 PathResult(PathResult<'a>),
2341 let find_binding_in_ns = |this: &mut Self, ns| {
2342 let binding = if let Some(module) = module {
2343 this.resolve_ident_in_module(
2351 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2352 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2353 this.early_resolve_ident_in_lexical_scope(
2362 let record_used_id = if record_used {
2363 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2367 match this.resolve_ident_in_lexical_scope(
2375 // we found a locally-imported or available item/module
2376 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2377 // we found a local variable or type param
2378 Some(LexicalScopeBinding::Res(res))
2379 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2381 record_segment_res(this, res);
2382 return FindBindingResult::PathResult(PathResult::NonModule(
2383 PartialRes::with_unresolved_segments(res, path.len() - 1),
2386 _ => Err(Determinacy::determined(record_used)),
2389 FindBindingResult::Binding(binding)
2391 let binding = match find_binding_in_ns(self, ns) {
2392 FindBindingResult::PathResult(x) => return x,
2393 FindBindingResult::Binding(binding) => binding,
2398 second_binding = Some(binding);
2400 let res = binding.res();
2401 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2402 if let Some(next_module) = binding.module() {
2403 module = Some(ModuleOrUniformRoot::Module(next_module));
2404 record_segment_res(self, res);
2405 } else if res == Res::ToolMod && i + 1 != path.len() {
2406 if binding.is_import() {
2410 "cannot use a tool module through an import",
2412 .span_note(binding.span, "the tool module imported here")
2415 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2416 return PathResult::NonModule(PartialRes::new(res));
2417 } else if res == Res::Err {
2418 return PathResult::NonModule(PartialRes::new(Res::Err));
2419 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2420 self.lint_if_path_starts_with_module(
2426 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2431 let label = format!(
2432 "`{}` is {} {}, not a module",
2438 return PathResult::Failed {
2442 is_error_from_last_segment: is_last,
2446 Err(Undetermined) => return PathResult::Indeterminate,
2447 Err(Determined) => {
2448 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2449 if opt_ns.is_some() && !module.is_normal() {
2450 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2451 module.res().unwrap(),
2456 let module_res = match module {
2457 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2460 let (label, suggestion) = if module_res == self.graph_root.res() {
2461 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2462 // Don't look up import candidates if this is a speculative resolve
2463 let mut candidates = if record_used {
2464 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2468 candidates.sort_by_cached_key(|c| {
2469 (c.path.segments.len(), pprust::path_to_string(&c.path))
2471 if let Some(candidate) = candidates.get(0) {
2473 String::from("unresolved import"),
2475 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2476 String::from("a similar path exists"),
2477 Applicability::MaybeIncorrect,
2480 } else if self.session.edition() == Edition::Edition2015 {
2481 (format!("maybe a missing crate `{}`?", ident), None)
2483 (format!("could not find `{}` in the crate root", ident), None)
2491 .map_or(false, |c| c.is_ascii_uppercase())
2493 // Check whether the name refers to an item in the value namespace.
2494 let suggestion = if ribs.is_some() {
2495 let match_span = match self.resolve_ident_in_lexical_scope(
2501 &ribs.unwrap()[ValueNS],
2503 // Name matches a local variable. For example:
2506 // let Foo: &str = "";
2507 // println!("{}", Foo::Bar); // Name refers to local
2508 // // variable `Foo`.
2511 Some(LexicalScopeBinding::Res(Res::Local(id))) => {
2512 Some(*self.pat_span_map.get(&id).unwrap())
2515 // Name matches item from a local name binding
2516 // created by `use` declaration. For example:
2518 // pub Foo: &str = "";
2522 // println!("{}", Foo::Bar); // Name refers to local
2523 // // binding `Foo`.
2526 Some(LexicalScopeBinding::Item(name_binding)) => {
2527 Some(name_binding.span)
2532 if let Some(span) = match_span {
2534 vec![(span, String::from(""))],
2535 format!("`{}` is defined here, but is not a type", ident),
2536 Applicability::MaybeIncorrect,
2545 (format!("use of undeclared type `{}`", ident), suggestion)
2548 format!("use of undeclared crate or module `{}`", ident),
2549 if ident.name == sym::alloc {
2553 "add `extern crate alloc` to use the `alloc` crate",
2555 Applicability::MaybeIncorrect,
2558 self.find_similarly_named_module_or_crate(
2560 &parent_scope.module,
2564 vec![(ident.span, sugg.to_string())],
2566 "there is a crate or module with a similar name",
2568 Applicability::MaybeIncorrect,
2575 let parent = path[i - 1].ident.name;
2576 let parent = match parent {
2577 // ::foo is mounted at the crate root for 2015, and is the extern
2578 // prelude for 2018+
2579 kw::PathRoot if self.session.edition() > Edition::Edition2015 => {
2580 "the list of imported crates".to_owned()
2582 kw::PathRoot | kw::Crate => "the crate root".to_owned(),
2584 format!("`{}`", parent)
2588 let mut msg = format!("could not find `{}` in {}", ident, parent);
2589 if ns == TypeNS || ns == ValueNS {
2590 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2591 if let FindBindingResult::Binding(Ok(binding)) =
2592 find_binding_in_ns(self, ns_to_try)
2594 let mut found = |what| {
2596 "expected {}, found {} `{}` in {}",
2603 if binding.module().is_some() {
2606 match binding.res() {
2607 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2608 _ => found(ns_to_try.descr()),
2615 return PathResult::Failed {
2619 is_error_from_last_segment: is_last,
2625 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2627 PathResult::Module(match module {
2628 Some(module) => module,
2629 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2630 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2634 fn lint_if_path_starts_with_module(
2636 crate_lint: CrateLint,
2639 second_binding: Option<&NameBinding<'_>>,
2641 let (diag_id, diag_span) = match crate_lint {
2642 CrateLint::No => return,
2643 CrateLint::SimplePath(id) => (id, path_span),
2644 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2645 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2648 let first_name = match path.get(0) {
2649 // In the 2018 edition this lint is a hard error, so nothing to do
2650 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2654 // We're only interested in `use` paths which should start with
2655 // `{{root}}` currently.
2656 if first_name != kw::PathRoot {
2661 // If this import looks like `crate::...` it's already good
2662 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2663 // Otherwise go below to see if it's an extern crate
2665 // If the path has length one (and it's `PathRoot` most likely)
2666 // then we don't know whether we're gonna be importing a crate or an
2667 // item in our crate. Defer this lint to elsewhere
2671 // If the first element of our path was actually resolved to an
2672 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2673 // warning, this looks all good!
2674 if let Some(binding) = second_binding {
2675 if let NameBindingKind::Import { import, .. } = binding.kind {
2676 // Careful: we still want to rewrite paths from renamed extern crates.
2677 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2683 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2684 self.lint_buffer.buffer_lint_with_diagnostic(
2685 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2688 "absolute paths must start with `self`, `super`, \
2689 `crate`, or an external crate name in the 2018 edition",
2694 // Validate a local resolution (from ribs).
2695 fn validate_res_from_ribs(
2702 original_rib_ident_def: Ident,
2703 all_ribs: &[Rib<'a>],
2705 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2706 debug!("validate_res_from_ribs({:?})", res);
2707 let ribs = &all_ribs[rib_index + 1..];
2709 // An invalid forward use of a generic parameter from a previous default.
2710 if let ForwardGenericParamBanRibKind = all_ribs[rib_index].kind {
2712 let res_error = if rib_ident.name == kw::SelfUpper {
2713 ResolutionError::SelfInGenericParamDefault
2715 ResolutionError::ForwardDeclaredGenericParam
2717 self.report_error(span, res_error);
2719 assert_eq!(res, Res::Err);
2725 use ResolutionError::*;
2726 let mut res_err = None;
2731 | ClosureOrAsyncRibKind
2733 | MacroDefinition(..)
2734 | ForwardGenericParamBanRibKind => {
2735 // Nothing to do. Continue.
2737 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2738 // This was an attempt to access an upvar inside a
2739 // named function item. This is not allowed, so we
2742 // We don't immediately trigger a resolve error, because
2743 // we want certain other resolution errors (namely those
2744 // emitted for `ConstantItemRibKind` below) to take
2746 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2749 ConstantItemRibKind(_, item) => {
2750 // Still doesn't deal with upvars
2752 let (span, resolution_error) =
2753 if let Some((ident, constant_item_kind)) = item {
2754 let kind_str = match constant_item_kind {
2755 ConstantItemKind::Const => "const",
2756 ConstantItemKind::Static => "static",
2760 AttemptToUseNonConstantValueInConstant(
2761 ident, "let", kind_str,
2767 AttemptToUseNonConstantValueInConstant(
2768 original_rib_ident_def,
2774 self.report_error(span, resolution_error);
2778 ConstParamTyRibKind => {
2780 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2786 if let Some(res_err) = res_err {
2787 self.report_error(span, res_err);
2791 Res::Def(DefKind::TyParam, _) | Res::SelfTy { .. } => {
2793 let has_generic_params: HasGenericParams = match rib.kind {
2795 | ClosureOrAsyncRibKind
2798 | MacroDefinition(..)
2799 | ForwardGenericParamBanRibKind => {
2800 // Nothing to do. Continue.
2804 ConstantItemRibKind(trivial, _) => {
2805 let features = self.session.features_untracked();
2806 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2807 if !(trivial || features.generic_const_exprs) {
2808 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2809 // we can't easily tell if it's generic at this stage, so we instead remember
2810 // this and then enforce the self type to be concrete later on.
2811 if let Res::SelfTy { trait_, alias_to: Some((def, _)) } = res {
2812 res = Res::SelfTy { trait_, alias_to: Some((def, true)) }
2817 ResolutionError::ParamInNonTrivialAnonConst {
2818 name: rib_ident.name,
2824 self.session.delay_span_bug(span, CG_BUG_STR);
2832 // This was an attempt to use a type parameter outside its scope.
2833 ItemRibKind(has_generic_params) => has_generic_params,
2834 FnItemRibKind => HasGenericParams::Yes,
2835 ConstParamTyRibKind => {
2839 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2849 ResolutionError::GenericParamsFromOuterFunction(
2858 Res::Def(DefKind::ConstParam, _) => {
2859 let mut ribs = ribs.iter().peekable();
2860 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2861 // When declaring const parameters inside function signatures, the first rib
2862 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2863 // (spuriously) conflicting with the const param.
2868 let has_generic_params = match rib.kind {
2870 | ClosureOrAsyncRibKind
2873 | MacroDefinition(..)
2874 | ForwardGenericParamBanRibKind => continue,
2876 ConstantItemRibKind(trivial, _) => {
2877 let features = self.session.features_untracked();
2878 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2879 if !(trivial || features.generic_const_exprs) {
2883 ResolutionError::ParamInNonTrivialAnonConst {
2884 name: rib_ident.name,
2890 self.session.delay_span_bug(span, CG_BUG_STR);
2897 ItemRibKind(has_generic_params) => has_generic_params,
2898 FnItemRibKind => HasGenericParams::Yes,
2899 ConstParamTyRibKind => {
2903 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2910 // This was an attempt to use a const parameter outside its scope.
2914 ResolutionError::GenericParamsFromOuterFunction(
2928 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2929 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2930 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2931 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2935 fn record_pat_span(&mut self, node: NodeId, span: Span) {
2936 debug!("(recording pat) recording {:?} for {:?}", node, span);
2937 self.pat_span_map.insert(node, span);
2940 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2941 vis.is_accessible_from(module.nearest_parent_mod(), self)
2944 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2945 if let Some(old_module) =
2946 self.binding_parent_modules.insert(Interned::new_unchecked(binding), module)
2948 if !ptr::eq(module, old_module) {
2949 span_bug!(binding.span, "parent module is reset for binding");
2954 fn disambiguate_macro_rules_vs_modularized(
2956 macro_rules: &'a NameBinding<'a>,
2957 modularized: &'a NameBinding<'a>,
2959 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2960 // is disambiguated to mitigate regressions from macro modularization.
2961 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2963 self.binding_parent_modules.get(&Interned::new_unchecked(macro_rules)),
2964 self.binding_parent_modules.get(&Interned::new_unchecked(modularized)),
2966 (Some(macro_rules), Some(modularized)) => {
2967 macro_rules.nearest_parent_mod() == modularized.nearest_parent_mod()
2968 && modularized.is_ancestor_of(macro_rules)
2974 fn report_errors(&mut self, krate: &Crate) {
2975 self.report_with_use_injections(krate);
2977 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2978 let msg = "macro-expanded `macro_export` macros from the current crate \
2979 cannot be referred to by absolute paths";
2980 self.lint_buffer.buffer_lint_with_diagnostic(
2981 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2985 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2989 for ambiguity_error in &self.ambiguity_errors {
2990 self.report_ambiguity_error(ambiguity_error);
2993 let mut reported_spans = FxHashSet::default();
2994 for error in &self.privacy_errors {
2995 if reported_spans.insert(error.dedup_span) {
2996 self.report_privacy_error(error);
3001 fn report_with_use_injections(&mut self, krate: &Crate) {
3002 for UseError { mut err, candidates, def_id, instead, suggestion } in
3003 self.use_injections.drain(..)
3005 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
3006 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
3010 if !candidates.is_empty() {
3011 diagnostics::show_candidates(
3020 } else if let Some((span, msg, sugg, appl)) = suggestion {
3021 err.span_suggestion(span, msg, sugg, appl);
3027 fn report_conflict<'b>(
3032 new_binding: &NameBinding<'b>,
3033 old_binding: &NameBinding<'b>,
3035 // Error on the second of two conflicting names
3036 if old_binding.span.lo() > new_binding.span.lo() {
3037 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
3040 let container = match parent.kind {
3041 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()),
3042 ModuleKind::Block(..) => "block",
3045 let old_noun = match old_binding.is_import() {
3047 false => "definition",
3050 let new_participle = match new_binding.is_import() {
3056 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
3058 if let Some(s) = self.name_already_seen.get(&name) {
3064 let old_kind = match (ns, old_binding.module()) {
3065 (ValueNS, _) => "value",
3066 (MacroNS, _) => "macro",
3067 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
3068 (TypeNS, Some(module)) if module.is_normal() => "module",
3069 (TypeNS, Some(module)) if module.is_trait() => "trait",
3070 (TypeNS, _) => "type",
3073 let msg = format!("the name `{}` is defined multiple times", name);
3075 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
3076 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3077 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
3078 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3079 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3081 _ => match (old_binding.is_import(), new_binding.is_import()) {
3082 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3083 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3084 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3089 "`{}` must be defined only once in the {} namespace of this {}",
3095 err.span_label(span, format!("`{}` re{} here", name, new_participle));
3097 self.session.source_map().guess_head_span(old_binding.span),
3098 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
3101 // See https://github.com/rust-lang/rust/issues/32354
3102 use NameBindingKind::Import;
3103 let import = match (&new_binding.kind, &old_binding.kind) {
3104 // If there are two imports where one or both have attributes then prefer removing the
3105 // import without attributes.
3106 (Import { import: new, .. }, Import { import: old, .. })
3108 !new_binding.span.is_dummy()
3109 && !old_binding.span.is_dummy()
3110 && (new.has_attributes || old.has_attributes)
3113 if old.has_attributes {
3114 Some((new, new_binding.span, true))
3116 Some((old, old_binding.span, true))
3119 // Otherwise prioritize the new binding.
3120 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
3121 Some((import, new_binding.span, other.is_import()))
3123 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
3124 Some((import, old_binding.span, other.is_import()))
3129 // Check if the target of the use for both bindings is the same.
3130 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
3131 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
3133 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
3134 // Only suggest removing an import if both bindings are to the same def, if both spans
3135 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
3136 // been introduced by an item.
3137 let should_remove_import = duplicate
3139 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
3142 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3143 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3145 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3146 // Simple case - remove the entire import. Due to the above match arm, this can
3147 // only be a single use so just remove it entirely.
3148 err.tool_only_span_suggestion(
3149 import.use_span_with_attributes,
3150 "remove unnecessary import",
3152 Applicability::MaybeIncorrect,
3155 Some((import, span, _)) => {
3156 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3162 self.name_already_seen.insert(name, span);
3165 /// This function adds a suggestion to change the binding name of a new import that conflicts
3166 /// with an existing import.
3168 /// ```text,ignore (diagnostic)
3169 /// help: you can use `as` to change the binding name of the import
3171 /// LL | use foo::bar as other_bar;
3172 /// | ^^^^^^^^^^^^^^^^^^^^^
3174 fn add_suggestion_for_rename_of_use(
3176 err: &mut Diagnostic,
3178 import: &Import<'_>,
3181 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3182 format!("Other{}", name)
3184 format!("other_{}", name)
3187 let mut suggestion = None;
3189 ImportKind::Single { type_ns_only: true, .. } => {
3190 suggestion = Some(format!("self as {}", suggested_name))
3192 ImportKind::Single { source, .. } => {
3194 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3196 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3197 if pos <= snippet.len() {
3198 suggestion = Some(format!(
3202 if snippet.ends_with(';') { ";" } else { "" }
3208 ImportKind::ExternCrate { source, target, .. } => {
3209 suggestion = Some(format!(
3210 "extern crate {} as {};",
3211 source.unwrap_or(target.name),
3215 _ => unreachable!(),
3218 let rename_msg = "you can use `as` to change the binding name of the import";
3219 if let Some(suggestion) = suggestion {
3220 err.span_suggestion(
3224 Applicability::MaybeIncorrect,
3227 err.span_label(binding_span, rename_msg);
3231 /// This function adds a suggestion to remove an unnecessary binding from an import that is
3232 /// nested. In the following example, this function will be invoked to remove the `a` binding
3233 /// in the second use statement:
3235 /// ```ignore (diagnostic)
3236 /// use issue_52891::a;
3237 /// use issue_52891::{d, a, e};
3240 /// The following suggestion will be added:
3242 /// ```ignore (diagnostic)
3243 /// use issue_52891::{d, a, e};
3244 /// ^-- help: remove unnecessary import
3247 /// If the nested use contains only one import then the suggestion will remove the entire
3250 /// It is expected that the provided import is nested - this isn't checked by the
3251 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3252 /// as characters expected by span manipulations won't be present.
3253 fn add_suggestion_for_duplicate_nested_use(
3255 err: &mut Diagnostic,
3256 import: &Import<'_>,
3259 assert!(import.is_nested());
3260 let message = "remove unnecessary import";
3262 // Two examples will be used to illustrate the span manipulations we're doing:
3264 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3265 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3266 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3267 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3269 let (found_closing_brace, span) =
3270 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3272 // If there was a closing brace then identify the span to remove any trailing commas from
3273 // previous imports.
3274 if found_closing_brace {
3275 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3276 err.tool_only_span_suggestion(
3280 Applicability::MaybeIncorrect,
3283 // Remove the entire line if we cannot extend the span back, this indicates an
3284 // `issue_52891::{self}` case.
3285 err.span_suggestion(
3286 import.use_span_with_attributes,
3289 Applicability::MaybeIncorrect,
3296 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3299 fn extern_prelude_get(
3303 ) -> Option<&'a NameBinding<'a>> {
3304 if ident.is_path_segment_keyword() {
3305 // Make sure `self`, `super` etc produce an error when passed to here.
3308 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3309 if let Some(binding) = entry.extern_crate_item {
3310 if !speculative && entry.introduced_by_item {
3311 self.record_use(ident, binding, false);
3315 let crate_id = if !speculative {
3316 let Some(crate_id) =
3317 self.crate_loader.process_path_extern(ident.name, ident.span) else { return Some(self.dummy_binding); };
3320 self.crate_loader.maybe_process_path_extern(ident.name)?
3322 let crate_root = self.expect_module(crate_id.as_def_id());
3324 (crate_root, ty::Visibility::Public, DUMMY_SP, LocalExpnId::ROOT)
3325 .to_name_binding(self.arenas),
3331 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3332 /// isn't something that can be returned because it can't be made to live that long,
3333 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3334 /// just that an error occurred.
3335 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3336 pub fn resolve_str_path_error(
3342 ) -> Result<(ast::Path, Res), ()> {
3343 let path = if path_str.starts_with("::") {
3346 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3347 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3348 .map(|i| self.new_ast_path_segment(i))
3357 .map(Ident::from_str)
3358 .map(|i| self.new_ast_path_segment(i))
3363 let module = self.expect_module(module_id);
3364 let parent_scope = &ParentScope::module(module, self);
3365 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3369 // Resolve a path passed from rustdoc or HIR lowering.
3370 fn resolve_ast_path(
3374 parent_scope: &ParentScope<'a>,
3375 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3376 match self.resolve_path(
3377 &Segment::from_path(path),
3384 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3385 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3386 Ok(path_res.base_res())
3388 PathResult::NonModule(..) => Err((
3390 ResolutionError::FailedToResolve {
3391 label: String::from("type-relative paths are not supported in this context"),
3395 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3396 PathResult::Failed { span, label, suggestion, .. } => {
3397 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3402 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3403 let mut seg = ast::PathSegment::from_ident(ident);
3404 seg.id = self.next_node_id();
3409 pub fn graph_root(&self) -> Module<'a> {
3414 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3419 /// For local modules returns only reexports, for external modules returns all children.
3420 pub fn module_children_or_reexports(&self, def_id: DefId) -> Vec<ModChild> {
3421 if let Some(def_id) = def_id.as_local() {
3422 self.reexport_map.get(&def_id).cloned().unwrap_or_default()
3424 self.cstore().module_children_untracked(def_id, self.session)
3428 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3430 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3431 def_id.as_local().map(|def_id| self.definitions.def_span(def_id))
3434 /// Checks if an expression refers to a function marked with
3435 /// `#[rustc_legacy_const_generics]` and returns the argument index list
3436 /// from the attribute.
3437 pub fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
3438 if let ExprKind::Path(None, path) = &expr.kind {
3439 // Don't perform legacy const generics rewriting if the path already
3440 // has generic arguments.
3441 if path.segments.last().unwrap().args.is_some() {
3445 let partial_res = self.partial_res_map.get(&expr.id)?;
3446 if partial_res.unresolved_segments() != 0 {
3450 if let Res::Def(def::DefKind::Fn, def_id) = partial_res.base_res() {
3451 // We only support cross-crate argument rewriting. Uses
3452 // within the same crate should be updated to use the new
3453 // const generics style.
3454 if def_id.is_local() {
3458 if let Some(v) = self.legacy_const_generic_args.get(&def_id) {
3464 .item_attrs_untracked(def_id, self.session)
3465 .find(|a| a.has_name(sym::rustc_legacy_const_generics))?;
3466 let mut ret = Vec::new();
3467 for meta in attr.meta_item_list()? {
3468 match meta.literal()?.kind {
3469 LitKind::Int(a, _) => ret.push(a as usize),
3470 _ => panic!("invalid arg index"),
3473 // Cache the lookup to avoid parsing attributes for an iterm multiple times.
3474 self.legacy_const_generic_args.insert(def_id, Some(ret.clone()));
3481 fn resolve_main(&mut self) {
3482 let module = self.graph_root;
3483 let ident = Ident::with_dummy_span(sym::main);
3484 let parent_scope = &ParentScope::module(module, self);
3486 let Ok(name_binding) = self.resolve_ident_in_module(
3487 ModuleOrUniformRoot::Module(module),
3497 let res = name_binding.res();
3498 let is_import = name_binding.is_import();
3499 let span = name_binding.span;
3500 if let Res::Def(DefKind::Fn, _) = res {
3501 self.record_use(ident, name_binding, false);
3503 self.main_def = Some(MainDefinition { res, is_import, span });
3507 fn names_to_string(names: &[Symbol]) -> String {
3508 let mut result = String::new();
3509 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3511 result.push_str("::");
3513 if Ident::with_dummy_span(*name).is_raw_guess() {
3514 result.push_str("r#");
3516 result.push_str(name.as_str());
3521 fn path_names_to_string(path: &Path) -> String {
3522 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3525 /// A somewhat inefficient routine to obtain the name of a module.
3526 fn module_to_string(module: Module<'_>) -> Option<String> {
3527 let mut names = Vec::new();
3529 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3530 if let ModuleKind::Def(.., name) = module.kind {
3531 if let Some(parent) = module.parent {
3533 collect_mod(names, parent);
3536 names.push(Symbol::intern("<opaque>"));
3537 collect_mod(names, module.parent.unwrap());
3540 collect_mod(&mut names, module);
3542 if names.is_empty() {
3546 Some(names_to_string(&names))
3549 #[derive(Copy, Clone, Debug)]
3551 /// Do not issue the lint.
3554 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3555 /// In this case, we can take the span of that path.
3558 /// This lint comes from a `use` statement. In this case, what we
3559 /// care about really is the *root* `use` statement; e.g., if we
3560 /// have nested things like `use a::{b, c}`, we care about the
3562 UsePath { root_id: NodeId, root_span: Span },
3564 /// This is the "trait item" from a fully qualified path. For example,
3565 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3566 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3567 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3571 fn node_id(&self) -> Option<NodeId> {
3573 CrateLint::No => None,
3574 CrateLint::SimplePath(id)
3575 | CrateLint::UsePath { root_id: id, .. }
3576 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3581 pub fn provide(providers: &mut Providers) {
3582 late::lifetimes::provide(providers);