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 `librustc_typeck`.
11 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
12 #![feature(bool_to_option)]
13 #![feature(crate_visibility_modifier)]
15 #![feature(or_patterns)]
16 #![recursion_limit = "256"]
18 pub use rustc_hir::def::{Namespace, PerNS};
22 use rustc_ast::ast::{self, FloatTy, IntTy, NodeId, UintTy};
23 use rustc_ast::ast::{Crate, CRATE_NODE_ID};
24 use rustc_ast::ast::{ItemKind, Path};
26 use rustc_ast::node_id::{NodeMap, NodeSet};
27 use rustc_ast::unwrap_or;
28 use rustc_ast::visit::{self, Visitor};
29 use rustc_ast_pretty::pprust;
30 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
31 use rustc_data_structures::ptr_key::PtrKey;
32 use rustc_data_structures::sync::Lrc;
33 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
34 use rustc_expand::base::SyntaxExtension;
35 use rustc_hir::def::Namespace::*;
36 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
37 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
38 use rustc_hir::definitions::{DefKey, Definitions};
39 use rustc_hir::PrimTy::{self, Bool, Char, Float, Int, Str, Uint};
40 use rustc_hir::{GlobMap, TraitMap};
41 use rustc_metadata::creader::{CStore, CrateLoader};
42 use rustc_middle::hir::exports::ExportMap;
43 use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn};
44 use rustc_middle::span_bug;
45 use rustc_middle::ty::query::Providers;
46 use rustc_middle::ty::{self, DefIdTree, ResolverOutputs};
47 use rustc_session::lint;
48 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
49 use rustc_session::Session;
50 use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency};
51 use rustc_span::source_map::Spanned;
52 use rustc_span::symbol::{kw, sym, Ident, Symbol};
53 use rustc_span::{Span, DUMMY_SP};
56 use std::cell::{Cell, RefCell};
57 use std::collections::BTreeSet;
58 use std::{cmp, fmt, iter, ptr};
60 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
61 use diagnostics::{ImportSuggestion, Suggestion};
62 use imports::{Import, ImportKind, ImportResolver, NameResolution};
63 use late::{HasGenericParams, PathSource, Rib, RibKind::*};
64 use macros::{MacroRulesBinding, MacroRulesScope};
66 type Res = def::Res<NodeId>;
68 mod build_reduced_graph;
81 #[derive(Copy, Clone, PartialEq, Debug)]
82 pub enum Determinacy {
88 fn determined(determined: bool) -> Determinacy {
89 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
93 /// A specific scope in which a name can be looked up.
94 /// This enum is currently used only for early resolution (imports and macros),
95 /// but not for late resolution yet.
96 #[derive(Clone, Copy)]
98 DeriveHelpers(ExpnId),
100 MacroRules(MacroRulesScope<'a>),
112 /// Names from different contexts may want to visit different subsets of all specific scopes
113 /// with different restrictions when looking up the resolution.
114 /// This enum is currently used only for early resolution (imports and macros),
115 /// but not for late resolution yet.
117 /// All scopes with the given namespace.
118 All(Namespace, /*is_import*/ bool),
119 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
120 AbsolutePath(Namespace),
121 /// All scopes with macro namespace and the given macro kind restriction.
125 /// Everything you need to know about a name's location to resolve it.
126 /// Serves as a starting point for the scope visitor.
127 /// This struct is currently used only for early resolution (imports and macros),
128 /// but not for late resolution yet.
129 #[derive(Clone, Copy, Debug)]
130 pub struct ParentScope<'a> {
133 macro_rules: MacroRulesScope<'a>,
134 derives: &'a [ast::Path],
137 impl<'a> ParentScope<'a> {
138 /// Creates a parent scope with the passed argument used as the module scope component,
139 /// and other scope components set to default empty values.
140 pub fn module(module: Module<'a>) -> ParentScope<'a> {
143 expansion: ExpnId::root(),
144 macro_rules: MacroRulesScope::Empty,
151 struct BindingError {
153 origin: BTreeSet<Span>,
154 target: BTreeSet<Span>,
158 impl PartialOrd for BindingError {
159 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
160 Some(self.cmp(other))
164 impl PartialEq for BindingError {
165 fn eq(&self, other: &BindingError) -> bool {
166 self.name == other.name
170 impl Ord for BindingError {
171 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
172 self.name.cmp(&other.name)
176 enum ResolutionError<'a> {
177 /// Error E0401: can't use type or const parameters from outer function.
178 GenericParamsFromOuterFunction(Res, HasGenericParams),
179 /// Error E0403: the name is already used for a type or const parameter in this generic
181 NameAlreadyUsedInParameterList(Symbol, Span),
182 /// Error E0407: method is not a member of trait.
183 MethodNotMemberOfTrait(Symbol, &'a str),
184 /// Error E0437: type is not a member of trait.
185 TypeNotMemberOfTrait(Symbol, &'a str),
186 /// Error E0438: const is not a member of trait.
187 ConstNotMemberOfTrait(Symbol, &'a str),
188 /// Error E0408: variable `{}` is not bound in all patterns.
189 VariableNotBoundInPattern(&'a BindingError),
190 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
191 VariableBoundWithDifferentMode(Symbol, Span),
192 /// Error E0415: identifier is bound more than once in this parameter list.
193 IdentifierBoundMoreThanOnceInParameterList(&'a str),
194 /// Error E0416: identifier is bound more than once in the same pattern.
195 IdentifierBoundMoreThanOnceInSamePattern(&'a str),
196 /// Error E0426: use of undeclared label.
197 UndeclaredLabel(&'a str, Option<Symbol>),
198 /// Error E0429: `self` imports are only allowed within a `{ }` list.
199 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
200 /// Error E0430: `self` import can only appear once in the list.
201 SelfImportCanOnlyAppearOnceInTheList,
202 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
203 SelfImportOnlyInImportListWithNonEmptyPrefix,
204 /// Error E0433: failed to resolve.
205 FailedToResolve { label: String, suggestion: Option<Suggestion> },
206 /// Error E0434: can't capture dynamic environment in a fn item.
207 CannotCaptureDynamicEnvironmentInFnItem,
208 /// Error E0435: attempt to use a non-constant value in a constant.
209 AttemptToUseNonConstantValueInConstant,
210 /// Error E0530: `X` bindings cannot shadow `Y`s.
211 BindingShadowsSomethingUnacceptable(&'a str, Symbol, &'a NameBinding<'a>),
212 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
213 ForwardDeclaredTyParam, // FIXME(const_generics:defaults)
214 /// Error E0735: type parameters with a default cannot use `Self`
215 SelfInTyParamDefault,
218 enum VisResolutionError<'a> {
219 Relative2018(Span, &'a ast::Path),
221 FailedToResolve(Span, String, Option<Suggestion>),
222 ExpectedFound(Span, String, Res),
227 // A minimal representation of a path segment. We use this in resolve because
228 // we synthesize 'path segments' which don't have the rest of an AST or HIR
230 #[derive(Clone, Copy, Debug)]
237 fn from_path(path: &Path) -> Vec<Segment> {
238 path.segments.iter().map(|s| s.into()).collect()
241 fn from_ident(ident: Ident) -> Segment {
242 Segment { ident, id: None }
245 fn names_to_string(segments: &[Segment]) -> String {
246 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
250 impl<'a> From<&'a ast::PathSegment> for Segment {
251 fn from(seg: &'a ast::PathSegment) -> Segment {
252 Segment { ident: seg.ident, id: Some(seg.id) }
256 struct UsePlacementFinder {
257 target_module: NodeId,
262 impl UsePlacementFinder {
263 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
264 let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
265 visit::walk_crate(&mut finder, krate);
266 (finder.span, finder.found_use)
270 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
273 module: &'tcx ast::Mod,
275 _: &[ast::Attribute],
278 if self.span.is_some() {
281 if node_id != self.target_module {
282 visit::walk_mod(self, module);
285 // find a use statement
286 for item in &module.items {
288 ItemKind::Use(..) => {
289 // don't suggest placing a use before the prelude
290 // import or other generated ones
291 if !item.span.from_expansion() {
292 self.span = Some(item.span.shrink_to_lo());
293 self.found_use = true;
297 // don't place use before extern crate
298 ItemKind::ExternCrate(_) => {}
299 // but place them before the first other item
301 if self.span.map_or(true, |span| item.span < span) {
302 if !item.span.from_expansion() {
303 // don't insert between attributes and an item
304 if item.attrs.is_empty() {
305 self.span = Some(item.span.shrink_to_lo());
307 // find the first attribute on the item
308 for attr in &item.attrs {
309 if self.span.map_or(true, |span| attr.span < span) {
310 self.span = Some(attr.span.shrink_to_lo());
322 /// An intermediate resolution result.
324 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
325 /// items are visible in their whole block, while `Res`es only from the place they are defined
328 enum LexicalScopeBinding<'a> {
329 Item(&'a NameBinding<'a>),
333 impl<'a> LexicalScopeBinding<'a> {
334 fn res(self) -> Res {
336 LexicalScopeBinding::Item(binding) => binding.res(),
337 LexicalScopeBinding::Res(res) => res,
342 #[derive(Copy, Clone, Debug)]
343 enum ModuleOrUniformRoot<'a> {
347 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
348 CrateRootAndExternPrelude,
350 /// Virtual module that denotes resolution in extern prelude.
351 /// Used for paths starting with `::` on 2018 edition.
354 /// Virtual module that denotes resolution in current scope.
355 /// Used only for resolving single-segment imports. The reason it exists is that import paths
356 /// are always split into two parts, the first of which should be some kind of module.
360 impl ModuleOrUniformRoot<'_> {
361 fn same_def(lhs: Self, rhs: Self) -> bool {
363 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
364 lhs.def_id() == rhs.def_id()
367 ModuleOrUniformRoot::CrateRootAndExternPrelude,
368 ModuleOrUniformRoot::CrateRootAndExternPrelude,
370 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
371 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
377 #[derive(Clone, Debug)]
378 enum PathResult<'a> {
379 Module(ModuleOrUniformRoot<'a>),
380 NonModule(PartialRes),
385 suggestion: Option<Suggestion>,
386 is_error_from_last_segment: bool,
391 /// An anonymous module; e.g., just a block.
396 /// { // This is an anonymous module
397 /// f(); // This resolves to (2) as we are inside the block.
400 /// f(); // Resolves to (1)
404 /// Any module with a name.
408 /// * A normal module ‒ either `mod from_file;` or `mod from_block { }`.
409 /// * A trait or an enum (it implicitly contains associated types, methods and variant
411 Def(DefKind, DefId, Symbol),
415 /// Get name of the module.
416 pub fn name(&self) -> Option<Symbol> {
418 ModuleKind::Block(..) => None,
419 ModuleKind::Def(.., name) => Some(*name),
424 /// A key that identifies a binding in a given `Module`.
426 /// Multiple bindings in the same module can have the same key (in a valid
427 /// program) if all but one of them come from glob imports.
428 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
430 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
434 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
435 /// `_` in the expanded AST that introduced this binding.
439 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
441 /// One node in the tree of modules.
442 pub struct ModuleData<'a> {
443 parent: Option<Module<'a>>,
446 // The def id of the closest normal module (`mod`) ancestor (including this module).
447 normal_ancestor_id: DefId,
449 // Mapping between names and their (possibly in-progress) resolutions in this module.
450 // Resolutions in modules from other crates are not populated until accessed.
451 lazy_resolutions: Resolutions<'a>,
452 // True if this is a module from other crate that needs to be populated on access.
453 populate_on_access: Cell<bool>,
455 // Macro invocations that can expand into items in this module.
456 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
458 no_implicit_prelude: bool,
460 glob_importers: RefCell<Vec<&'a Import<'a>>>,
461 globs: RefCell<Vec<&'a Import<'a>>>,
463 // Used to memoize the traits in this module for faster searches through all traits in scope.
464 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
466 /// Span of the module itself. Used for error reporting.
472 type Module<'a> = &'a ModuleData<'a>;
474 impl<'a> ModuleData<'a> {
476 parent: Option<Module<'a>>,
478 normal_ancestor_id: DefId,
486 lazy_resolutions: Default::default(),
487 populate_on_access: Cell::new(!normal_ancestor_id.is_local()),
488 unexpanded_invocations: Default::default(),
489 no_implicit_prelude: false,
490 glob_importers: RefCell::new(Vec::new()),
491 globs: RefCell::new(Vec::new()),
492 traits: RefCell::new(None),
498 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
500 R: AsMut<Resolver<'a>>,
501 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
503 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
504 if let Some(binding) = name_resolution.borrow().binding {
505 f(resolver, key.ident, key.ns, binding);
510 fn res(&self) -> Option<Res> {
512 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
517 fn def_id(&self) -> Option<DefId> {
519 ModuleKind::Def(_, def_id, _) => Some(def_id),
524 // `self` resolves to the first module ancestor that `is_normal`.
525 fn is_normal(&self) -> bool {
527 ModuleKind::Def(DefKind::Mod, _, _) => true,
532 fn is_trait(&self) -> bool {
534 ModuleKind::Def(DefKind::Trait, _, _) => true,
539 fn nearest_item_scope(&'a self) -> Module<'a> {
541 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
542 self.parent.expect("enum or trait module without a parent")
548 fn is_ancestor_of(&self, mut other: &Self) -> bool {
549 while !ptr::eq(self, other) {
550 if let Some(parent) = other.parent {
560 impl<'a> fmt::Debug for ModuleData<'a> {
561 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
562 write!(f, "{:?}", self.res())
566 /// Records a possibly-private value, type, or module definition.
567 #[derive(Clone, Debug)]
568 pub struct NameBinding<'a> {
569 kind: NameBindingKind<'a>,
570 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
576 pub trait ToNameBinding<'a> {
577 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
580 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
581 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
586 #[derive(Clone, Debug)]
587 enum NameBindingKind<'a> {
588 Res(Res, /* is_macro_export */ bool),
590 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
593 impl<'a> NameBindingKind<'a> {
594 /// Is this a name binding of a import?
595 fn is_import(&self) -> bool {
597 NameBindingKind::Import { .. } => true,
603 struct PrivacyError<'a> {
605 binding: &'a NameBinding<'a>,
609 struct UseError<'a> {
610 err: DiagnosticBuilder<'a>,
611 /// Attach `use` statements for these candidates.
612 candidates: Vec<ImportSuggestion>,
613 /// The `NodeId` of the module to place the use-statements in.
615 /// Whether the diagnostic should state that it's "better".
617 /// Extra free form suggestion. Currently used to suggest new type parameter.
618 suggestion: Option<(Span, &'static str, String, Applicability)>,
621 #[derive(Clone, Copy, PartialEq, Debug)]
626 MacroRulesVsModularized,
634 fn descr(self) -> &'static str {
636 AmbiguityKind::Import => "name vs any other name during import resolution",
637 AmbiguityKind::BuiltinAttr => "built-in attribute vs any other name",
638 AmbiguityKind::DeriveHelper => "derive helper attribute vs any other name",
639 AmbiguityKind::MacroRulesVsModularized => {
640 "`macro_rules` vs non-`macro_rules` from other module"
642 AmbiguityKind::GlobVsOuter => {
643 "glob import vs any other name from outer scope during import/macro resolution"
645 AmbiguityKind::GlobVsGlob => "glob import vs glob import in the same module",
646 AmbiguityKind::GlobVsExpanded => {
647 "glob import vs macro-expanded name in the same \
648 module during import/macro resolution"
650 AmbiguityKind::MoreExpandedVsOuter => {
651 "macro-expanded name vs less macro-expanded name \
652 from outer scope during import/macro resolution"
658 /// Miscellaneous bits of metadata for better ambiguity error reporting.
659 #[derive(Clone, Copy, PartialEq)]
660 enum AmbiguityErrorMisc {
667 struct AmbiguityError<'a> {
670 b1: &'a NameBinding<'a>,
671 b2: &'a NameBinding<'a>,
672 misc1: AmbiguityErrorMisc,
673 misc2: AmbiguityErrorMisc,
676 impl<'a> NameBinding<'a> {
677 fn module(&self) -> Option<Module<'a>> {
679 NameBindingKind::Module(module) => Some(module),
680 NameBindingKind::Import { binding, .. } => binding.module(),
685 fn res(&self) -> Res {
687 NameBindingKind::Res(res, _) => res,
688 NameBindingKind::Module(module) => module.res().unwrap(),
689 NameBindingKind::Import { binding, .. } => binding.res(),
693 fn is_ambiguity(&self) -> bool {
694 self.ambiguity.is_some()
696 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
701 // We sometimes need to treat variants as `pub` for backwards compatibility.
702 fn pseudo_vis(&self) -> ty::Visibility {
703 if self.is_variant() && self.res().def_id().is_local() {
704 ty::Visibility::Public
710 fn is_variant(&self) -> bool {
712 NameBindingKind::Res(
713 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
720 fn is_extern_crate(&self) -> bool {
722 NameBindingKind::Import {
723 import: &Import { kind: ImportKind::ExternCrate { .. }, .. },
726 NameBindingKind::Module(&ModuleData {
727 kind: ModuleKind::Def(DefKind::Mod, def_id, _),
729 }) => def_id.index == CRATE_DEF_INDEX,
734 fn is_import(&self) -> bool {
736 NameBindingKind::Import { .. } => true,
741 fn is_glob_import(&self) -> bool {
743 NameBindingKind::Import { import, .. } => import.is_glob(),
748 fn is_importable(&self) -> bool {
750 Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _) => false,
755 fn is_macro_def(&self) -> bool {
757 NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
762 fn macro_kind(&self) -> Option<MacroKind> {
763 self.res().macro_kind()
766 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
767 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
768 // Then this function returns `true` if `self` may emerge from a macro *after* that
769 // in some later round and screw up our previously found resolution.
770 // See more detailed explanation in
771 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
772 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
773 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
774 // Expansions are partially ordered, so "may appear after" is an inversion of
775 // "certainly appears before or simultaneously" and includes unordered cases.
776 let self_parent_expansion = self.expansion;
777 let other_parent_expansion = binding.expansion;
778 let certainly_before_other_or_simultaneously =
779 other_parent_expansion.is_descendant_of(self_parent_expansion);
780 let certainly_before_invoc_or_simultaneously =
781 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
782 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
786 /// Interns the names of the primitive types.
788 /// All other types are defined somewhere and possibly imported, but the primitive ones need
789 /// special handling, since they have no place of origin.
790 struct PrimitiveTypeTable {
791 primitive_types: FxHashMap<Symbol, PrimTy>,
794 impl PrimitiveTypeTable {
795 fn new() -> PrimitiveTypeTable {
796 let mut table = FxHashMap::default();
798 table.insert(sym::bool, Bool);
799 table.insert(sym::char, Char);
800 table.insert(sym::f32, Float(FloatTy::F32));
801 table.insert(sym::f64, Float(FloatTy::F64));
802 table.insert(sym::isize, Int(IntTy::Isize));
803 table.insert(sym::i8, Int(IntTy::I8));
804 table.insert(sym::i16, Int(IntTy::I16));
805 table.insert(sym::i32, Int(IntTy::I32));
806 table.insert(sym::i64, Int(IntTy::I64));
807 table.insert(sym::i128, Int(IntTy::I128));
808 table.insert(sym::str, Str);
809 table.insert(sym::usize, Uint(UintTy::Usize));
810 table.insert(sym::u8, Uint(UintTy::U8));
811 table.insert(sym::u16, Uint(UintTy::U16));
812 table.insert(sym::u32, Uint(UintTy::U32));
813 table.insert(sym::u64, Uint(UintTy::U64));
814 table.insert(sym::u128, Uint(UintTy::U128));
815 Self { primitive_types: table }
819 #[derive(Debug, Default, Clone)]
820 pub struct ExternPreludeEntry<'a> {
821 extern_crate_item: Option<&'a NameBinding<'a>>,
822 pub introduced_by_item: bool,
825 /// The main resolver class.
827 /// This is the visitor that walks the whole crate.
828 pub struct Resolver<'a> {
829 session: &'a Session,
831 definitions: Definitions,
833 graph_root: Module<'a>,
835 prelude: Option<Module<'a>>,
836 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
838 /// N.B., this is used only for better diagnostics, not name resolution itself.
839 has_self: FxHashSet<DefId>,
841 /// Names of fields of an item `DefId` accessible with dot syntax.
842 /// Used for hints during error reporting.
843 field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>,
845 /// All imports known to succeed or fail.
846 determined_imports: Vec<&'a Import<'a>>,
848 /// All non-determined imports.
849 indeterminate_imports: Vec<&'a Import<'a>>,
851 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
852 /// We are resolving a last import segment during import validation.
853 last_import_segment: bool,
854 /// This binding should be ignored during in-module resolution, so that we don't get
855 /// "self-confirming" import resolutions during import validation.
856 blacklisted_binding: Option<&'a NameBinding<'a>>,
858 /// The idents for the primitive types.
859 primitive_type_table: PrimitiveTypeTable,
861 /// Resolutions for nodes that have a single resolution.
862 partial_res_map: NodeMap<PartialRes>,
863 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
864 import_res_map: NodeMap<PerNS<Option<Res>>>,
865 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
866 label_res_map: NodeMap<NodeId>,
868 /// `CrateNum` resolutions of `extern crate` items.
869 extern_crate_map: NodeMap<CrateNum>,
870 export_map: ExportMap<NodeId>,
871 trait_map: TraitMap<NodeId>,
873 /// A map from nodes to anonymous modules.
874 /// Anonymous modules are pseudo-modules that are implicitly created around items
875 /// contained within blocks.
877 /// For example, if we have this:
885 /// There will be an anonymous module created around `g` with the ID of the
886 /// entry block for `f`.
887 block_map: NodeMap<Module<'a>>,
888 /// A fake module that contains no definition and no prelude. Used so that
889 /// some AST passes can generate identifiers that only resolve to local or
891 empty_module: Module<'a>,
892 module_map: FxHashMap<LocalDefId, Module<'a>>,
893 extern_module_map: FxHashMap<DefId, Module<'a>>,
894 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
895 underscore_disambiguator: u32,
897 /// Maps glob imports to the names of items actually imported.
900 used_imports: FxHashSet<(NodeId, Namespace)>,
901 maybe_unused_trait_imports: NodeSet,
902 maybe_unused_extern_crates: Vec<(NodeId, Span)>,
904 /// Privacy errors are delayed until the end in order to deduplicate them.
905 privacy_errors: Vec<PrivacyError<'a>>,
906 /// Ambiguity errors are delayed for deduplication.
907 ambiguity_errors: Vec<AmbiguityError<'a>>,
908 /// `use` injections are delayed for better placement and deduplication.
909 use_injections: Vec<UseError<'a>>,
910 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
911 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
913 arenas: &'a ResolverArenas<'a>,
914 dummy_binding: &'a NameBinding<'a>,
916 crate_loader: CrateLoader<'a>,
917 macro_names: FxHashSet<Ident>,
918 builtin_macros: FxHashMap<Symbol, SyntaxExtension>,
919 registered_attrs: FxHashSet<Ident>,
920 registered_tools: FxHashSet<Ident>,
921 macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
922 all_macros: FxHashMap<Symbol, Res>,
923 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
924 dummy_ext_bang: Lrc<SyntaxExtension>,
925 dummy_ext_derive: Lrc<SyntaxExtension>,
926 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
927 macro_defs: FxHashMap<ExpnId, DefId>,
928 local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
929 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
930 unused_macros: NodeMap<Span>,
931 proc_macro_stubs: NodeSet,
932 /// Traces collected during macro resolution and validated when it's complete.
933 single_segment_macro_resolutions:
934 Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>,
935 multi_segment_macro_resolutions:
936 Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>,
937 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
938 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
939 /// Derive macros cannot modify the item themselves and have to store the markers in the global
940 /// context, so they attach the markers to derive container IDs using this resolver table.
941 containers_deriving_copy: FxHashSet<ExpnId>,
942 /// Parent scopes in which the macros were invoked.
943 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
944 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
945 /// `macro_rules` scopes *produced* by expanding the macro invocations,
946 /// include all the `macro_rules` items and other invocations generated by them.
947 output_macro_rules_scopes: FxHashMap<ExpnId, MacroRulesScope<'a>>,
948 /// Helper attributes that are in scope for the given expansion.
949 helper_attrs: FxHashMap<ExpnId, Vec<Ident>>,
951 /// Avoid duplicated errors for "name already defined".
952 name_already_seen: FxHashMap<Symbol, Span>,
954 potentially_unused_imports: Vec<&'a Import<'a>>,
956 /// Table for mapping struct IDs into struct constructor IDs,
957 /// it's not used during normal resolution, only for better error reporting.
958 struct_constructors: DefIdMap<(Res, ty::Visibility)>,
960 /// Features enabled for this crate.
961 active_features: FxHashSet<Symbol>,
963 /// Stores enum visibilities to properly build a reduced graph
964 /// when visiting the correspondent variants.
965 variant_vis: DefIdMap<ty::Visibility>,
967 lint_buffer: LintBuffer,
969 next_node_id: NodeId,
972 /// Nothing really interesting here; it just provides memory for the rest of the crate.
974 pub struct ResolverArenas<'a> {
975 modules: arena::TypedArena<ModuleData<'a>>,
976 local_modules: RefCell<Vec<Module<'a>>>,
977 name_bindings: arena::TypedArena<NameBinding<'a>>,
978 imports: arena::TypedArena<Import<'a>>,
979 name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
980 macro_rules_bindings: arena::TypedArena<MacroRulesBinding<'a>>,
981 ast_paths: arena::TypedArena<ast::Path>,
984 impl<'a> ResolverArenas<'a> {
985 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
986 let module = self.modules.alloc(module);
987 if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
988 self.local_modules.borrow_mut().push(module);
992 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
993 self.local_modules.borrow()
995 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
996 self.name_bindings.alloc(name_binding)
998 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
999 self.imports.alloc(import)
1001 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1002 self.name_resolutions.alloc(Default::default())
1004 fn alloc_macro_rules_binding(
1006 binding: MacroRulesBinding<'a>,
1007 ) -> &'a MacroRulesBinding<'a> {
1008 self.macro_rules_bindings.alloc(binding)
1010 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1011 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1015 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1016 fn as_mut(&mut self) -> &mut Resolver<'a> {
1021 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1022 fn parent(self, id: DefId) -> Option<DefId> {
1023 match id.as_local() {
1024 Some(id) => self.definitions.def_key(id).parent,
1025 None => self.cstore().def_key(id).parent,
1027 .map(|index| DefId { index, ..id })
1031 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1032 /// the resolver is no longer needed as all the relevant information is inline.
1033 impl rustc_ast_lowering::Resolver for Resolver<'_> {
1034 fn def_key(&mut self, id: DefId) -> DefKey {
1035 if let Some(id) = id.as_local() {
1036 self.definitions().def_key(id)
1038 self.cstore().def_key(id)
1042 fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
1043 self.cstore().item_generics_num_lifetimes(def_id, sess)
1046 fn resolve_str_path(
1049 crate_root: Option<Symbol>,
1050 components: &[Symbol],
1052 ) -> (ast::Path, Res) {
1053 let root = if crate_root.is_some() { kw::PathRoot } else { kw::Crate };
1054 let segments = iter::once(Ident::with_dummy_span(root))
1058 .chain(components.iter().cloned())
1059 .map(Ident::with_dummy_span),
1061 .map(|i| self.new_ast_path_segment(i))
1062 .collect::<Vec<_>>();
1064 let path = ast::Path { span, segments };
1066 let parent_scope = &ParentScope::module(self.graph_root);
1067 let res = match self.resolve_ast_path(&path, ns, parent_scope) {
1069 Err((span, error)) => {
1070 self.report_error(span, error);
1077 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1078 self.partial_res_map.get(&id).cloned()
1081 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1082 self.import_res_map.get(&id).cloned().unwrap_or_default()
1085 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1086 self.label_res_map.get(&id).cloned()
1089 fn definitions(&mut self) -> &mut Definitions {
1090 &mut self.definitions
1093 fn lint_buffer(&mut self) -> &mut LintBuffer {
1094 &mut self.lint_buffer
1097 fn next_node_id(&mut self) -> NodeId {
1102 impl<'a> Resolver<'a> {
1104 session: &'a Session,
1107 metadata_loader: &'a MetadataLoaderDyn,
1108 arenas: &'a ResolverArenas<'a>,
1110 let root_def_id = DefId::local(CRATE_DEF_INDEX);
1111 let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid);
1112 let graph_root = arenas.alloc_module(ModuleData {
1113 no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
1114 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1116 let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid);
1117 let empty_module = arenas.alloc_module(ModuleData {
1118 no_implicit_prelude: true,
1127 let mut module_map = FxHashMap::default();
1128 module_map.insert(LocalDefId { local_def_index: CRATE_DEF_INDEX }, graph_root);
1130 let mut definitions = Definitions::default();
1131 definitions.create_root_def(crate_name, session.local_crate_disambiguator());
1133 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1137 .filter(|(_, entry)| entry.add_prelude)
1138 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1141 if !attr::contains_name(&krate.attrs, sym::no_core) {
1142 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1143 if !attr::contains_name(&krate.attrs, sym::no_std) {
1144 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1145 if session.rust_2018() {
1146 extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default());
1151 let (registered_attrs, registered_tools) =
1152 macros::registered_attrs_and_tools(session, &krate.attrs);
1154 let mut invocation_parent_scopes = FxHashMap::default();
1155 invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root));
1157 let mut macro_defs = FxHashMap::default();
1158 macro_defs.insert(ExpnId::root(), root_def_id);
1160 let features = session.features_untracked();
1161 let non_macro_attr =
1162 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1169 // The outermost module has def ID 0; this is not reflected in the
1175 has_self: FxHashSet::default(),
1176 field_names: FxHashMap::default(),
1178 determined_imports: Vec::new(),
1179 indeterminate_imports: Vec::new(),
1181 last_import_segment: false,
1182 blacklisted_binding: None,
1184 primitive_type_table: PrimitiveTypeTable::new(),
1186 partial_res_map: Default::default(),
1187 import_res_map: Default::default(),
1188 label_res_map: Default::default(),
1189 extern_crate_map: Default::default(),
1190 export_map: FxHashMap::default(),
1191 trait_map: Default::default(),
1192 underscore_disambiguator: 0,
1195 block_map: Default::default(),
1196 extern_module_map: FxHashMap::default(),
1197 binding_parent_modules: FxHashMap::default(),
1198 ast_transform_scopes: FxHashMap::default(),
1200 glob_map: Default::default(),
1202 used_imports: FxHashSet::default(),
1203 maybe_unused_trait_imports: Default::default(),
1204 maybe_unused_extern_crates: Vec::new(),
1206 privacy_errors: Vec::new(),
1207 ambiguity_errors: Vec::new(),
1208 use_injections: Vec::new(),
1209 macro_expanded_macro_export_errors: BTreeSet::new(),
1212 dummy_binding: arenas.alloc_name_binding(NameBinding {
1213 kind: NameBindingKind::Res(Res::Err, false),
1215 expansion: ExpnId::root(),
1217 vis: ty::Visibility::Public,
1220 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1221 macro_names: FxHashSet::default(),
1222 builtin_macros: Default::default(),
1225 macro_use_prelude: FxHashMap::default(),
1226 all_macros: FxHashMap::default(),
1227 macro_map: FxHashMap::default(),
1228 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1229 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1230 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1231 invocation_parent_scopes,
1232 output_macro_rules_scopes: Default::default(),
1233 helper_attrs: Default::default(),
1235 local_macro_def_scopes: FxHashMap::default(),
1236 name_already_seen: FxHashMap::default(),
1237 potentially_unused_imports: Vec::new(),
1238 struct_constructors: Default::default(),
1239 unused_macros: Default::default(),
1240 proc_macro_stubs: Default::default(),
1241 single_segment_macro_resolutions: Default::default(),
1242 multi_segment_macro_resolutions: Default::default(),
1243 builtin_attrs: Default::default(),
1244 containers_deriving_copy: Default::default(),
1245 active_features: features
1246 .declared_lib_features
1248 .map(|(feat, ..)| *feat)
1249 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1251 variant_vis: Default::default(),
1252 lint_buffer: LintBuffer::default(),
1253 next_node_id: NodeId::from_u32(1),
1257 pub fn next_node_id(&mut self) -> NodeId {
1262 .expect("input too large; ran out of NodeIds");
1263 self.next_node_id = ast::NodeId::from_usize(next);
1267 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1268 &mut self.lint_buffer
1271 pub fn arenas() -> ResolverArenas<'a> {
1275 pub fn into_outputs(self) -> ResolverOutputs {
1276 let definitions = self.definitions;
1278 let mut map = FxHashMap::default();
1279 for (k, v) in self.export_map.into_iter() {
1283 .map(|e| e.map_id(|id| definitions.node_id_to_hir_id(id)))
1290 let mut map = FxHashMap::default();
1291 for (k, v) in self.trait_map.into_iter() {
1293 definitions.node_id_to_hir_id(k),
1295 .map(|tc| tc.map_import_ids(|id| definitions.node_id_to_hir_id(id)))
1301 let maybe_unused_trait_imports = self
1302 .maybe_unused_trait_imports
1304 .map(|id| definitions.local_def_id(id))
1306 let maybe_unused_extern_crates = self
1307 .maybe_unused_extern_crates
1309 .map(|(id, sp)| (definitions.local_def_id(id).to_def_id(), sp))
1312 definitions: definitions,
1313 cstore: Box::new(self.crate_loader.into_cstore()),
1314 extern_crate_map: self.extern_crate_map,
1317 glob_map: self.glob_map,
1318 maybe_unused_trait_imports,
1319 maybe_unused_extern_crates,
1320 extern_prelude: self
1323 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1328 pub fn clone_outputs(&self) -> ResolverOutputs {
1330 definitions: self.definitions.clone(),
1331 cstore: Box::new(self.cstore().clone()),
1332 extern_crate_map: self.extern_crate_map.clone(),
1334 let mut map = FxHashMap::default();
1335 for (k, v) in self.export_map.iter() {
1339 .map(|e| e.clone().map_id(|id| self.definitions.node_id_to_hir_id(id)))
1346 let mut map = FxHashMap::default();
1347 for (k, v) in self.trait_map.iter() {
1349 self.definitions.node_id_to_hir_id(k.clone()),
1353 .map_import_ids(|id| self.definitions.node_id_to_hir_id(id))
1360 glob_map: self.glob_map.clone(),
1361 maybe_unused_trait_imports: self
1362 .maybe_unused_trait_imports
1364 .map(|id| self.definitions.local_def_id(id.clone()))
1366 maybe_unused_extern_crates: self
1367 .maybe_unused_extern_crates
1369 .map(|(id, sp)| (self.definitions.local_def_id(id.clone()).to_def_id(), sp.clone()))
1371 extern_prelude: self
1374 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1379 pub fn cstore(&self) -> &CStore {
1380 self.crate_loader.cstore()
1383 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1384 self.non_macro_attrs[mark_used as usize].clone()
1387 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1389 MacroKind::Bang => self.dummy_ext_bang.clone(),
1390 MacroKind::Derive => self.dummy_ext_derive.clone(),
1391 MacroKind::Attr => self.non_macro_attr(true),
1395 /// Runs the function on each namespace.
1396 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1402 fn is_builtin_macro(&mut self, res: Res) -> bool {
1403 self.get_macro(res).map_or(false, |ext| ext.is_builtin)
1406 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1408 match self.macro_defs.get(&ctxt.outer_expn()) {
1409 Some(&def_id) => return def_id,
1410 None => ctxt.remove_mark(),
1415 /// Entry point to crate resolution.
1416 pub fn resolve_crate(&mut self, krate: &Crate) {
1417 let _prof_timer = self.session.prof.generic_activity("resolve_crate");
1419 ImportResolver { r: self }.finalize_imports();
1420 self.finalize_macro_resolutions();
1422 self.late_resolve_crate(krate);
1424 self.check_unused(krate);
1425 self.report_errors(krate);
1426 self.crate_loader.postprocess(krate);
1433 normal_ancestor_id: DefId,
1437 let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span);
1438 self.arenas.alloc_module(module)
1441 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1442 let ident = ident.normalize_to_macros_2_0();
1443 let disambiguator = if ident.name == kw::Underscore {
1444 self.underscore_disambiguator += 1;
1445 self.underscore_disambiguator
1449 BindingKey { ident, ns, disambiguator }
1452 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1453 if module.populate_on_access.get() {
1454 module.populate_on_access.set(false);
1455 self.build_reduced_graph_external(module);
1457 &module.lazy_resolutions
1464 ) -> &'a RefCell<NameResolution<'a>> {
1466 .resolutions(module)
1469 .or_insert_with(|| self.arenas.alloc_name_resolution())
1476 used_binding: &'a NameBinding<'a>,
1477 is_lexical_scope: bool,
1479 if let Some((b2, kind)) = used_binding.ambiguity {
1480 self.ambiguity_errors.push(AmbiguityError {
1485 misc1: AmbiguityErrorMisc::None,
1486 misc2: AmbiguityErrorMisc::None,
1489 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1490 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1491 // but not introduce it, as used if they are accessed from lexical scope.
1492 if is_lexical_scope {
1493 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1494 if let Some(crate_item) = entry.extern_crate_item {
1495 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1502 import.used.set(true);
1503 self.used_imports.insert((import.id, ns));
1504 self.add_to_glob_map(&import, ident);
1505 self.record_use(ident, ns, binding, false);
1510 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1511 if import.is_glob() {
1512 self.glob_map.entry(import.id).or_default().insert(ident.name);
1516 /// A generic scope visitor.
1517 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1518 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1521 scope_set: ScopeSet,
1522 parent_scope: &ParentScope<'a>,
1524 mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>,
1526 // General principles:
1527 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1528 // built into the language or standard library. This way we can add new names into the
1529 // language or standard library without breaking user code.
1530 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1531 // Places to search (in order of decreasing priority):
1533 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1534 // (open set, not controlled).
1535 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1536 // (open, not controlled).
1537 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1538 // 4. Tool modules (closed, controlled right now, but not in the future).
1539 // 5. Standard library prelude (de-facto closed, controlled).
1540 // 6. Language prelude (closed, controlled).
1542 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1543 // (open set, not controlled).
1544 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1545 // (open, not controlled).
1546 // 3. Standard library prelude (de-facto closed, controlled).
1548 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1549 // are currently reported as errors. They should be higher in priority than preludes
1550 // and probably even names in modules according to the "general principles" above. They
1551 // also should be subject to restricted shadowing because are effectively produced by
1552 // derives (you need to resolve the derive first to add helpers into scope), but they
1553 // should be available before the derive is expanded for compatibility.
1554 // It's mess in general, so we are being conservative for now.
1555 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1556 // priority than prelude macros, but create ambiguities with macros in modules.
1557 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1558 // (open, not controlled). Have higher priority than prelude macros, but create
1559 // ambiguities with `macro_rules`.
1560 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1561 // 4a. User-defined prelude from macro-use
1562 // (open, the open part is from macro expansions, not controlled).
1563 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1564 // 4c. Standard library prelude (de-facto closed, controlled).
1565 // 6. Language prelude: builtin attributes (closed, controlled).
1567 let rust_2015 = ident.span.rust_2015();
1568 let (ns, macro_kind, is_absolute_path) = match scope_set {
1569 ScopeSet::All(ns, _) => (ns, None, false),
1570 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1571 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1573 // Jump out of trait or enum modules, they do not act as scopes.
1574 let module = parent_scope.module.nearest_item_scope();
1575 let mut scope = match ns {
1576 _ if is_absolute_path => Scope::CrateRoot,
1577 TypeNS | ValueNS => Scope::Module(module),
1578 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1580 let mut ident = ident.normalize_to_macros_2_0();
1581 let mut use_prelude = !module.no_implicit_prelude;
1584 let visit = match scope {
1585 // Derive helpers are not in scope when resolving derives in the same container.
1586 Scope::DeriveHelpers(expn_id) => {
1587 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1589 Scope::DeriveHelpersCompat => true,
1590 Scope::MacroRules(..) => true,
1591 Scope::CrateRoot => true,
1592 Scope::Module(..) => true,
1593 Scope::RegisteredAttrs => use_prelude,
1594 Scope::MacroUsePrelude => use_prelude || rust_2015,
1595 Scope::BuiltinAttrs => true,
1596 Scope::ExternPrelude => use_prelude || is_absolute_path,
1597 Scope::ToolPrelude => use_prelude,
1598 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1599 Scope::BuiltinTypes => true,
1603 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) {
1604 return break_result;
1608 scope = match scope {
1609 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1610 // Derive helpers are not visible to code generated by bang or derive macros.
1611 let expn_data = expn_id.expn_data();
1612 match expn_data.kind {
1614 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1615 Scope::DeriveHelpersCompat
1617 _ => Scope::DeriveHelpers(expn_data.parent),
1620 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1621 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1622 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope {
1623 MacroRulesScope::Binding(binding) => {
1624 Scope::MacroRules(binding.parent_macro_rules_scope)
1626 MacroRulesScope::Invocation(invoc_id) => Scope::MacroRules(
1627 self.output_macro_rules_scopes
1630 .unwrap_or(self.invocation_parent_scopes[&invoc_id].macro_rules),
1632 MacroRulesScope::Empty => Scope::Module(module),
1634 Scope::CrateRoot => match ns {
1636 ident.span.adjust(ExpnId::root());
1637 Scope::ExternPrelude
1639 ValueNS | MacroNS => break,
1641 Scope::Module(module) => {
1642 use_prelude = !module.no_implicit_prelude;
1643 match self.hygienic_lexical_parent(module, &mut ident.span) {
1644 Some(parent_module) => Scope::Module(parent_module),
1646 ident.span.adjust(ExpnId::root());
1648 TypeNS => Scope::ExternPrelude,
1649 ValueNS => Scope::StdLibPrelude,
1650 MacroNS => Scope::RegisteredAttrs,
1655 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1656 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1657 Scope::BuiltinAttrs => break, // nowhere else to search
1658 Scope::ExternPrelude if is_absolute_path => break,
1659 Scope::ExternPrelude => Scope::ToolPrelude,
1660 Scope::ToolPrelude => Scope::StdLibPrelude,
1661 Scope::StdLibPrelude => match ns {
1662 TypeNS => Scope::BuiltinTypes,
1663 ValueNS => break, // nowhere else to search
1664 MacroNS => Scope::BuiltinAttrs,
1666 Scope::BuiltinTypes => break, // nowhere else to search
1673 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1674 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1675 /// `ident` in the first scope that defines it (or None if no scopes define it).
1677 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1678 /// the items are defined in the block. For example,
1681 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1684 /// g(); // This resolves to the local variable `g` since it shadows the item.
1688 /// Invariant: This must only be called during main resolution, not during
1689 /// import resolution.
1690 fn resolve_ident_in_lexical_scope(
1694 parent_scope: &ParentScope<'a>,
1695 record_used_id: Option<NodeId>,
1698 ) -> Option<LexicalScopeBinding<'a>> {
1699 assert!(ns == TypeNS || ns == ValueNS);
1700 if ident.name == kw::Invalid {
1701 return Some(LexicalScopeBinding::Res(Res::Err));
1703 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1704 // FIXME(jseyfried) improve `Self` hygiene
1705 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1706 (empty_span, empty_span)
1707 } else if ns == TypeNS {
1708 let normalized_span = ident.span.normalize_to_macros_2_0();
1709 (normalized_span, normalized_span)
1711 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1713 ident.span = general_span;
1714 let normalized_ident = Ident { span: normalized_span, ..ident };
1716 // Walk backwards up the ribs in scope.
1717 let record_used = record_used_id.is_some();
1718 let mut module = self.graph_root;
1719 for i in (0..ribs.len()).rev() {
1720 debug!("walk rib\n{:?}", ribs[i].bindings);
1721 // Use the rib kind to determine whether we are resolving parameters
1722 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1723 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1724 if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() {
1725 // The ident resolves to a type parameter or local variable.
1726 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1736 module = match ribs[i].kind {
1737 ModuleRibKind(module) => module,
1738 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1739 // If an invocation of this macro created `ident`, give up on `ident`
1740 // and switch to `ident`'s source from the macro definition.
1741 ident.span.remove_mark();
1747 let item = self.resolve_ident_in_module_unadjusted(
1748 ModuleOrUniformRoot::Module(module),
1755 if let Ok(binding) = item {
1756 // The ident resolves to an item.
1757 return Some(LexicalScopeBinding::Item(binding));
1761 ModuleKind::Block(..) => {} // We can see through blocks
1766 ident = normalized_ident;
1767 let mut poisoned = None;
1769 let opt_module = if let Some(node_id) = record_used_id {
1770 self.hygienic_lexical_parent_with_compatibility_fallback(
1777 self.hygienic_lexical_parent(module, &mut ident.span)
1779 module = unwrap_or!(opt_module, break);
1780 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1781 let result = self.resolve_ident_in_module_unadjusted(
1782 ModuleOrUniformRoot::Module(module),
1785 adjusted_parent_scope,
1792 if let Some(node_id) = poisoned {
1793 self.lint_buffer.buffer_lint_with_diagnostic(
1794 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1797 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1798 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(ident.span),
1801 return Some(LexicalScopeBinding::Item(binding));
1803 Err(Determined) => continue,
1804 Err(Undetermined) => {
1805 span_bug!(ident.span, "undetermined resolution during main resolution pass")
1810 if !module.no_implicit_prelude {
1811 ident.span.adjust(ExpnId::root());
1813 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1814 return Some(LexicalScopeBinding::Item(binding));
1816 if let Some(ident) = self.registered_tools.get(&ident) {
1818 (Res::ToolMod, ty::Visibility::Public, ident.span, ExpnId::root())
1819 .to_name_binding(self.arenas);
1820 return Some(LexicalScopeBinding::Item(binding));
1823 if let Some(prelude) = self.prelude {
1824 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1825 ModuleOrUniformRoot::Module(prelude),
1832 return Some(LexicalScopeBinding::Item(binding));
1838 if let Some(prim_ty) = self.primitive_type_table.primitive_types.get(&ident.name) {
1840 (Res::PrimTy(*prim_ty), ty::Visibility::Public, DUMMY_SP, ExpnId::root())
1841 .to_name_binding(self.arenas);
1842 return Some(LexicalScopeBinding::Item(binding));
1849 fn hygienic_lexical_parent(
1853 ) -> Option<Module<'a>> {
1854 if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1855 return Some(self.macro_def_scope(span.remove_mark()));
1858 if let ModuleKind::Block(..) = module.kind {
1859 return Some(module.parent.unwrap().nearest_item_scope());
1865 fn hygienic_lexical_parent_with_compatibility_fallback(
1870 poisoned: &mut Option<NodeId>,
1871 ) -> Option<Module<'a>> {
1872 if let module @ Some(..) = self.hygienic_lexical_parent(module, span) {
1876 // We need to support the next case under a deprecation warning
1879 // ---- begin: this comes from a proc macro derive
1880 // mod implementation_details {
1881 // // Note that `MyStruct` is not in scope here.
1882 // impl SomeTrait for MyStruct { ... }
1886 // So we have to fall back to the module's parent during lexical resolution in this case.
1887 if let Some(parent) = module.parent {
1888 // Inner module is inside the macro, parent module is outside of the macro.
1889 if module.expansion != parent.expansion
1890 && module.expansion.is_descendant_of(parent.expansion)
1892 // The macro is a proc macro derive
1893 if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
1894 if let Some(ext) = self.get_macro_by_def_id(def_id) {
1895 if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
1896 if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1897 *poisoned = Some(node_id);
1898 return module.parent;
1909 fn resolve_ident_in_module(
1911 module: ModuleOrUniformRoot<'a>,
1914 parent_scope: &ParentScope<'a>,
1917 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1918 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
1919 .map_err(|(determinacy, _)| determinacy)
1922 fn resolve_ident_in_module_ext(
1924 module: ModuleOrUniformRoot<'a>,
1927 parent_scope: &ParentScope<'a>,
1930 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
1931 let tmp_parent_scope;
1932 let mut adjusted_parent_scope = parent_scope;
1934 ModuleOrUniformRoot::Module(m) => {
1935 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
1937 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
1938 adjusted_parent_scope = &tmp_parent_scope;
1941 ModuleOrUniformRoot::ExternPrelude => {
1942 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
1944 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
1948 self.resolve_ident_in_module_unadjusted_ext(
1952 adjusted_parent_scope,
1959 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
1960 let mut ctxt = ident.span.ctxt();
1961 let mark = if ident.name == kw::DollarCrate {
1962 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
1963 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
1964 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
1965 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
1966 // definitions actually produced by `macro` and `macro` definitions produced by
1967 // `macro_rules!`, but at least such configurations are not stable yet.
1968 ctxt = ctxt.normalize_to_macro_rules();
1969 let mut iter = ctxt.marks().into_iter().rev().peekable();
1970 let mut result = None;
1971 // Find the last opaque mark from the end if it exists.
1972 while let Some(&(mark, transparency)) = iter.peek() {
1973 if transparency == Transparency::Opaque {
1974 result = Some(mark);
1980 // Then find the last semi-transparent mark from the end if it exists.
1981 for (mark, transparency) in iter {
1982 if transparency == Transparency::SemiTransparent {
1983 result = Some(mark);
1990 ctxt = ctxt.normalize_to_macros_2_0();
1991 ctxt.adjust(ExpnId::root())
1993 let module = match mark {
1994 Some(def) => self.macro_def_scope(def),
1995 None => return self.graph_root,
1997 self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
2000 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2001 let mut module = self.get_module(module.normal_ancestor_id);
2002 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2003 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
2004 module = self.get_module(parent.normal_ancestor_id);
2012 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2013 parent_scope: &ParentScope<'a>,
2016 crate_lint: CrateLint,
2017 ) -> PathResult<'a> {
2018 self.resolve_path_with_ribs(
2029 fn resolve_path_with_ribs(
2032 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2033 parent_scope: &ParentScope<'a>,
2036 crate_lint: CrateLint,
2037 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2038 ) -> PathResult<'a> {
2039 let mut module = None;
2040 let mut allow_super = true;
2041 let mut second_binding = None;
2044 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2045 path_span={:?}, crate_lint={:?})",
2046 path, opt_ns, record_used, path_span, crate_lint,
2049 for (i, &Segment { ident, id }) in path.iter().enumerate() {
2050 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2051 let record_segment_res = |this: &mut Self, res| {
2053 if let Some(id) = id {
2054 if !this.partial_res_map.contains_key(&id) {
2055 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2056 this.record_partial_res(id, PartialRes::new(res));
2062 let is_last = i == path.len() - 1;
2063 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2064 let name = ident.name;
2066 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2069 if allow_super && name == kw::Super {
2070 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2071 let self_module = match i {
2072 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2074 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2078 if let Some(self_module) = self_module {
2079 if let Some(parent) = self_module.parent {
2080 module = Some(ModuleOrUniformRoot::Module(
2081 self.resolve_self(&mut ctxt, parent),
2086 let msg = "there are too many leading `super` keywords".to_string();
2087 return PathResult::Failed {
2091 is_error_from_last_segment: false,
2095 if name == kw::SelfLower {
2096 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2097 module = Some(ModuleOrUniformRoot::Module(
2098 self.resolve_self(&mut ctxt, parent_scope.module),
2102 if name == kw::PathRoot && ident.span.rust_2018() {
2103 module = Some(ModuleOrUniformRoot::ExternPrelude);
2106 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2107 // `::a::b` from 2015 macro on 2018 global edition
2108 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2111 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2112 // `::a::b`, `crate::a::b` or `$crate::a::b`
2113 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2119 // Report special messages for path segment keywords in wrong positions.
2120 if ident.is_path_segment_keyword() && i != 0 {
2121 let name_str = if name == kw::PathRoot {
2122 "crate root".to_string()
2124 format!("`{}`", name)
2126 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2127 format!("global paths cannot start with {}", name_str)
2129 format!("{} in paths can only be used in start position", name_str)
2131 return PathResult::Failed {
2135 is_error_from_last_segment: false,
2139 enum FindBindingResult<'a> {
2140 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2141 PathResult(PathResult<'a>),
2143 let find_binding_in_ns = |this: &mut Self, ns| {
2144 let binding = if let Some(module) = module {
2145 this.resolve_ident_in_module(
2153 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2154 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2155 this.early_resolve_ident_in_lexical_scope(
2164 let record_used_id = if record_used {
2165 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2169 match this.resolve_ident_in_lexical_scope(
2177 // we found a locally-imported or available item/module
2178 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2179 // we found a local variable or type param
2180 Some(LexicalScopeBinding::Res(res))
2181 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2183 record_segment_res(this, res);
2184 return FindBindingResult::PathResult(PathResult::NonModule(
2185 PartialRes::with_unresolved_segments(res, path.len() - 1),
2188 _ => Err(Determinacy::determined(record_used)),
2191 FindBindingResult::Binding(binding)
2193 let binding = match find_binding_in_ns(self, ns) {
2194 FindBindingResult::PathResult(x) => return x,
2195 FindBindingResult::Binding(binding) => binding,
2200 second_binding = Some(binding);
2202 let res = binding.res();
2203 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2204 if let Some(next_module) = binding.module() {
2205 module = Some(ModuleOrUniformRoot::Module(next_module));
2206 record_segment_res(self, res);
2207 } else if res == Res::ToolMod && i + 1 != path.len() {
2208 if binding.is_import() {
2212 "cannot use a tool module through an import",
2214 .span_note(binding.span, "the tool module imported here")
2217 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2218 return PathResult::NonModule(PartialRes::new(res));
2219 } else if res == Res::Err {
2220 return PathResult::NonModule(PartialRes::new(Res::Err));
2221 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2222 self.lint_if_path_starts_with_module(
2228 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2233 let label = format!(
2234 "`{}` is {} {}, not a module",
2240 return PathResult::Failed {
2244 is_error_from_last_segment: is_last,
2248 Err(Undetermined) => return PathResult::Indeterminate,
2249 Err(Determined) => {
2250 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2251 if opt_ns.is_some() && !module.is_normal() {
2252 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2253 module.res().unwrap(),
2258 let module_res = match module {
2259 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2262 let (label, suggestion) = if module_res == self.graph_root.res() {
2263 let is_mod = |res| match res {
2264 Res::Def(DefKind::Mod, _) => true,
2267 let mut candidates = self.lookup_import_candidates(ident, TypeNS, is_mod);
2268 candidates.sort_by_cached_key(|c| {
2269 (c.path.segments.len(), pprust::path_to_string(&c.path))
2271 if let Some(candidate) = candidates.get(0) {
2273 String::from("unresolved import"),
2275 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2276 String::from("a similar path exists"),
2277 Applicability::MaybeIncorrect,
2281 (format!("maybe a missing crate `{}`?", ident), None)
2284 (format!("use of undeclared type or module `{}`", ident), None)
2287 format!("could not find `{}` in `{}`", ident, path[i - 1].ident);
2288 if ns == TypeNS || ns == ValueNS {
2289 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2290 if let FindBindingResult::Binding(Ok(binding)) =
2291 find_binding_in_ns(self, ns_to_try)
2293 let mut found = |what| {
2295 "expected {}, found {} `{}` in `{}`",
2302 if binding.module().is_some() {
2305 match binding.res() {
2306 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2307 _ => found(ns_to_try.descr()),
2314 return PathResult::Failed {
2318 is_error_from_last_segment: is_last,
2324 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2326 PathResult::Module(match module {
2327 Some(module) => module,
2328 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2329 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2333 fn lint_if_path_starts_with_module(
2335 crate_lint: CrateLint,
2338 second_binding: Option<&NameBinding<'_>>,
2340 let (diag_id, diag_span) = match crate_lint {
2341 CrateLint::No => return,
2342 CrateLint::SimplePath(id) => (id, path_span),
2343 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2344 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2347 let first_name = match path.get(0) {
2348 // In the 2018 edition this lint is a hard error, so nothing to do
2349 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2353 // We're only interested in `use` paths which should start with
2354 // `{{root}}` currently.
2355 if first_name != kw::PathRoot {
2360 // If this import looks like `crate::...` it's already good
2361 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2362 // Otherwise go below to see if it's an extern crate
2364 // If the path has length one (and it's `PathRoot` most likely)
2365 // then we don't know whether we're gonna be importing a crate or an
2366 // item in our crate. Defer this lint to elsewhere
2370 // If the first element of our path was actually resolved to an
2371 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2372 // warning, this looks all good!
2373 if let Some(binding) = second_binding {
2374 if let NameBindingKind::Import { import, .. } = binding.kind {
2375 // Careful: we still want to rewrite paths from renamed extern crates.
2376 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2382 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2383 self.lint_buffer.buffer_lint_with_diagnostic(
2384 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2387 "absolute paths must start with `self`, `super`, \
2388 `crate`, or an external crate name in the 2018 edition",
2393 // Validate a local resolution (from ribs).
2394 fn validate_res_from_ribs(
2401 all_ribs: &[Rib<'a>],
2403 debug!("validate_res_from_ribs({:?})", res);
2404 let ribs = &all_ribs[rib_index + 1..];
2406 // An invalid forward use of a type parameter from a previous default.
2407 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2409 let res_error = if rib_ident.name == kw::SelfUpper {
2410 ResolutionError::SelfInTyParamDefault
2412 ResolutionError::ForwardDeclaredTyParam
2414 self.report_error(span, res_error);
2416 assert_eq!(res, Res::Err);
2422 use ResolutionError::*;
2423 let mut res_err = None;
2429 | MacroDefinition(..)
2430 | ForwardTyParamBanRibKind => {
2431 // Nothing to do. Continue.
2433 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2434 // This was an attempt to access an upvar inside a
2435 // named function item. This is not allowed, so we
2438 // We don't immediately trigger a resolve error, because
2439 // we want certain other resolution errors (namely those
2440 // emitted for `ConstantItemRibKind` below) to take
2442 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2445 ConstantItemRibKind => {
2446 // Still doesn't deal with upvars
2448 self.report_error(span, AttemptToUseNonConstantValueInConstant);
2454 if let Some(res_err) = res_err {
2455 self.report_error(span, res_err);
2459 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2461 let has_generic_params = match rib.kind {
2465 | MacroDefinition(..)
2466 | ForwardTyParamBanRibKind
2467 | ConstantItemRibKind => {
2468 // Nothing to do. Continue.
2471 // This was an attempt to use a type parameter outside its scope.
2472 ItemRibKind(has_generic_params) => has_generic_params,
2473 FnItemRibKind => HasGenericParams::Yes,
2479 ResolutionError::GenericParamsFromOuterFunction(
2488 Res::Def(DefKind::ConstParam, _) => {
2489 let mut ribs = ribs.iter().peekable();
2490 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2491 // When declaring const parameters inside function signatures, the first rib
2492 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2493 // (spuriously) conflicting with the const param.
2497 let has_generic_params = match rib.kind {
2498 ItemRibKind(has_generic_params) => has_generic_params,
2499 FnItemRibKind => HasGenericParams::Yes,
2503 // This was an attempt to use a const parameter outside its scope.
2507 ResolutionError::GenericParamsFromOuterFunction(
2521 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2522 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2523 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2524 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2528 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2529 vis.is_accessible_from(module.normal_ancestor_id, self)
2532 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2533 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2534 if !ptr::eq(module, old_module) {
2535 span_bug!(binding.span, "parent module is reset for binding");
2540 fn disambiguate_macro_rules_vs_modularized(
2542 macro_rules: &'a NameBinding<'a>,
2543 modularized: &'a NameBinding<'a>,
2545 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2546 // is disambiguated to mitigate regressions from macro modularization.
2547 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2549 self.binding_parent_modules.get(&PtrKey(macro_rules)),
2550 self.binding_parent_modules.get(&PtrKey(modularized)),
2552 (Some(macro_rules), Some(modularized)) => {
2553 macro_rules.normal_ancestor_id == modularized.normal_ancestor_id
2554 && modularized.is_ancestor_of(macro_rules)
2560 fn report_errors(&mut self, krate: &Crate) {
2561 self.report_with_use_injections(krate);
2563 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2564 let msg = "macro-expanded `macro_export` macros from the current crate \
2565 cannot be referred to by absolute paths";
2566 self.lint_buffer.buffer_lint_with_diagnostic(
2567 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2571 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2575 for ambiguity_error in &self.ambiguity_errors {
2576 self.report_ambiguity_error(ambiguity_error);
2579 let mut reported_spans = FxHashSet::default();
2580 for error in &self.privacy_errors {
2581 if reported_spans.insert(error.dedup_span) {
2582 self.report_privacy_error(error);
2587 fn report_with_use_injections(&mut self, krate: &Crate) {
2588 for UseError { mut err, candidates, node_id, better, suggestion } in
2589 self.use_injections.drain(..)
2591 let (span, found_use) = UsePlacementFinder::check(krate, node_id);
2592 if !candidates.is_empty() {
2593 diagnostics::show_candidates(&mut err, span, &candidates, better, found_use);
2594 } else if let Some((span, msg, sugg, appl)) = suggestion {
2595 err.span_suggestion(span, msg, sugg, appl);
2601 fn report_conflict<'b>(
2606 new_binding: &NameBinding<'b>,
2607 old_binding: &NameBinding<'b>,
2609 // Error on the second of two conflicting names
2610 if old_binding.span.lo() > new_binding.span.lo() {
2611 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2614 let container = match parent.kind {
2615 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id().unwrap()),
2616 ModuleKind::Block(..) => "block",
2619 let old_noun = match old_binding.is_import() {
2621 false => "definition",
2624 let new_participle = match new_binding.is_import() {
2630 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
2632 if let Some(s) = self.name_already_seen.get(&name) {
2638 let old_kind = match (ns, old_binding.module()) {
2639 (ValueNS, _) => "value",
2640 (MacroNS, _) => "macro",
2641 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2642 (TypeNS, Some(module)) if module.is_normal() => "module",
2643 (TypeNS, Some(module)) if module.is_trait() => "trait",
2644 (TypeNS, _) => "type",
2647 let msg = format!("the name `{}` is defined multiple times", name);
2649 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2650 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2651 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2652 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2653 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2655 _ => match (old_binding.is_import(), new_binding.is_import()) {
2656 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2657 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2658 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2663 "`{}` must be defined only once in the {} namespace of this {}",
2669 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2671 self.session.source_map().guess_head_span(old_binding.span),
2672 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2675 // See https://github.com/rust-lang/rust/issues/32354
2676 use NameBindingKind::Import;
2677 let import = match (&new_binding.kind, &old_binding.kind) {
2678 // If there are two imports where one or both have attributes then prefer removing the
2679 // import without attributes.
2680 (Import { import: new, .. }, Import { import: old, .. })
2682 !new_binding.span.is_dummy()
2683 && !old_binding.span.is_dummy()
2684 && (new.has_attributes || old.has_attributes)
2687 if old.has_attributes {
2688 Some((new, new_binding.span, true))
2690 Some((old, old_binding.span, true))
2693 // Otherwise prioritize the new binding.
2694 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
2695 Some((import, new_binding.span, other.is_import()))
2697 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
2698 Some((import, old_binding.span, other.is_import()))
2703 // Check if the target of the use for both bindings is the same.
2704 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2705 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2707 self.extern_prelude.get(&ident).map(|entry| entry.introduced_by_item).unwrap_or(true);
2708 // Only suggest removing an import if both bindings are to the same def, if both spans
2709 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2710 // been introduced by a item.
2711 let should_remove_import = duplicate
2713 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2716 Some((import, span, true)) if should_remove_import && import.is_nested() => {
2717 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
2719 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
2720 // Simple case - remove the entire import. Due to the above match arm, this can
2721 // only be a single use so just remove it entirely.
2722 err.tool_only_span_suggestion(
2723 import.use_span_with_attributes,
2724 "remove unnecessary import",
2726 Applicability::MaybeIncorrect,
2729 Some((import, span, _)) => {
2730 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
2736 self.name_already_seen.insert(name, span);
2739 /// This function adds a suggestion to change the binding name of a new import that conflicts
2740 /// with an existing import.
2742 /// ```text,ignore (diagnostic)
2743 /// help: you can use `as` to change the binding name of the import
2745 /// LL | use foo::bar as other_bar;
2746 /// | ^^^^^^^^^^^^^^^^^^^^^
2748 fn add_suggestion_for_rename_of_use(
2750 err: &mut DiagnosticBuilder<'_>,
2752 import: &Import<'_>,
2755 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
2756 format!("Other{}", name)
2758 format!("other_{}", name)
2761 let mut suggestion = None;
2763 ImportKind::Single { type_ns_only: true, .. } => {
2764 suggestion = Some(format!("self as {}", suggested_name))
2766 ImportKind::Single { source, .. } => {
2768 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
2770 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
2771 if pos <= snippet.len() {
2772 suggestion = Some(format!(
2776 if snippet.ends_with(';') { ";" } else { "" }
2782 ImportKind::ExternCrate { source, target, .. } => {
2783 suggestion = Some(format!(
2784 "extern crate {} as {};",
2785 source.unwrap_or(target.name),
2789 _ => unreachable!(),
2792 let rename_msg = "you can use `as` to change the binding name of the import";
2793 if let Some(suggestion) = suggestion {
2794 err.span_suggestion(
2798 Applicability::MaybeIncorrect,
2801 err.span_label(binding_span, rename_msg);
2805 /// This function adds a suggestion to remove a unnecessary binding from an import that is
2806 /// nested. In the following example, this function will be invoked to remove the `a` binding
2807 /// in the second use statement:
2809 /// ```ignore (diagnostic)
2810 /// use issue_52891::a;
2811 /// use issue_52891::{d, a, e};
2814 /// The following suggestion will be added:
2816 /// ```ignore (diagnostic)
2817 /// use issue_52891::{d, a, e};
2818 /// ^-- help: remove unnecessary import
2821 /// If the nested use contains only one import then the suggestion will remove the entire
2824 /// It is expected that the provided import is nested - this isn't checked by the
2825 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
2826 /// as characters expected by span manipulations won't be present.
2827 fn add_suggestion_for_duplicate_nested_use(
2829 err: &mut DiagnosticBuilder<'_>,
2830 import: &Import<'_>,
2833 assert!(import.is_nested());
2834 let message = "remove unnecessary import";
2836 // Two examples will be used to illustrate the span manipulations we're doing:
2838 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
2839 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
2840 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
2841 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
2843 let (found_closing_brace, span) =
2844 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
2846 // If there was a closing brace then identify the span to remove any trailing commas from
2847 // previous imports.
2848 if found_closing_brace {
2849 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
2850 err.tool_only_span_suggestion(
2854 Applicability::MaybeIncorrect,
2857 // Remove the entire line if we cannot extend the span back, this indicates a
2858 // `issue_52891::{self}` case.
2859 err.span_suggestion(
2860 import.use_span_with_attributes,
2863 Applicability::MaybeIncorrect,
2870 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
2873 fn extern_prelude_get(
2877 ) -> Option<&'a NameBinding<'a>> {
2878 if ident.is_path_segment_keyword() {
2879 // Make sure `self`, `super` etc produce an error when passed to here.
2882 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
2883 if let Some(binding) = entry.extern_crate_item {
2884 if !speculative && entry.introduced_by_item {
2885 self.record_use(ident, TypeNS, binding, false);
2889 let crate_id = if !speculative {
2890 self.crate_loader.process_path_extern(ident.name, ident.span)
2892 self.crate_loader.maybe_process_path_extern(ident.name, ident.span)?
2894 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
2896 (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
2897 .to_name_binding(self.arenas),
2903 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
2904 /// isn't something that can be returned because it can't be made to live that long,
2905 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
2906 /// just that an error occurred.
2907 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
2908 pub fn resolve_str_path_error(
2914 ) -> Result<(ast::Path, Res), ()> {
2915 let path = if path_str.starts_with("::") {
2918 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
2919 .chain(path_str.split("::").skip(1).map(Ident::from_str))
2920 .map(|i| self.new_ast_path_segment(i))
2928 .map(Ident::from_str)
2929 .map(|i| self.new_ast_path_segment(i))
2933 let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| {
2934 let def_id = self.definitions.local_def_id(module_id);
2935 self.module_map.get(&def_id).copied().unwrap_or(self.graph_root)
2937 let parent_scope = &ParentScope::module(module);
2938 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
2942 // Resolve a path passed from rustdoc or HIR lowering.
2943 fn resolve_ast_path(
2947 parent_scope: &ParentScope<'a>,
2948 ) -> Result<Res, (Span, ResolutionError<'a>)> {
2949 match self.resolve_path(
2950 &Segment::from_path(path),
2957 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
2958 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
2959 Ok(path_res.base_res())
2961 PathResult::NonModule(..) => Err((
2963 ResolutionError::FailedToResolve {
2964 label: String::from("type-relative paths are not supported in this context"),
2968 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
2969 PathResult::Failed { span, label, suggestion, .. } => {
2970 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
2975 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
2976 let mut seg = ast::PathSegment::from_ident(ident);
2977 seg.id = self.next_node_id();
2982 pub fn graph_root(&self) -> Module<'a> {
2987 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
2992 fn names_to_string(names: &[Symbol]) -> String {
2993 let mut result = String::new();
2994 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
2996 result.push_str("::");
2998 if Ident::with_dummy_span(*name).is_raw_guess() {
2999 result.push_str("r#");
3001 result.push_str(&name.as_str());
3006 fn path_names_to_string(path: &Path) -> String {
3007 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3010 /// A somewhat inefficient routine to obtain the name of a module.
3011 fn module_to_string(module: Module<'_>) -> Option<String> {
3012 let mut names = Vec::new();
3014 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3015 if let ModuleKind::Def(.., name) = module.kind {
3016 if let Some(parent) = module.parent {
3018 collect_mod(names, parent);
3021 names.push(Symbol::intern("<opaque>"));
3022 collect_mod(names, module.parent.unwrap());
3025 collect_mod(&mut names, module);
3027 if names.is_empty() {
3031 Some(names_to_string(&names))
3034 #[derive(Copy, Clone, Debug)]
3036 /// Do not issue the lint.
3039 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3040 /// In this case, we can take the span of that path.
3043 /// This lint comes from a `use` statement. In this case, what we
3044 /// care about really is the *root* `use` statement; e.g., if we
3045 /// have nested things like `use a::{b, c}`, we care about the
3047 UsePath { root_id: NodeId, root_span: Span },
3049 /// This is the "trait item" from a fully qualified path. For example,
3050 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3051 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3052 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3056 fn node_id(&self) -> Option<NodeId> {
3058 CrateLint::No => None,
3059 CrateLint::SimplePath(id)
3060 | CrateLint::UsePath { root_id: id, .. }
3061 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3066 pub fn provide(providers: &mut Providers<'_>) {
3067 late::lifetimes::provide(providers);