1 //! This crate is responsible for the part of name resolution that doesn't require type checker.
3 //! Module structure of the crate is built here.
4 //! Paths in macros, imports, expressions, types, patterns are resolved here.
5 //! Label names are resolved here as well.
7 //! Type-relative name resolution (methods, fields, associated items) happens in `librustc_typeck`.
8 //! Lifetime names are resolved in `librustc/middle/resolve_lifetime.rs`.
10 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
12 #![feature(crate_visibility_modifier)]
13 #![feature(label_break_value)]
16 #![recursion_limit="256"]
18 pub use rustc::hir::def::{Namespace, PerNS};
22 use rustc::hir::map::Definitions;
23 use rustc::hir::{self, PrimTy, Bool, Char, Float, Int, Uint, Str};
24 use rustc::middle::cstore::CrateStore;
25 use rustc::session::Session;
27 use rustc::hir::def::{self, DefKind, PartialRes, CtorKind, CtorOf, NonMacroAttrKind, ExportMap};
28 use rustc::hir::def::Namespace::*;
29 use rustc::hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
30 use rustc::hir::{TraitMap, GlobMap};
31 use rustc::ty::{self, DefIdTree};
32 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
35 use rustc_metadata::creader::CrateLoader;
36 use rustc_metadata::cstore::CStore;
38 use syntax::ext::hygiene::{ExpnId, Transparency, SyntaxContext};
39 use syntax::ast::{self, Name, NodeId, Ident, FloatTy, IntTy, UintTy};
40 use syntax::ext::base::{SyntaxExtension, MacroKind, SpecialDerives};
41 use syntax::symbol::{kw, sym};
43 use syntax::visit::{self, Visitor};
45 use syntax::ast::{CRATE_NODE_ID, Crate};
46 use syntax::ast::{ItemKind, Path};
47 use syntax::{struct_span_err, unwrap_or};
48 use syntax::source_map::Spanned;
50 use syntax_pos::{Span, DUMMY_SP};
51 use errors::{Applicability, DiagnosticBuilder};
55 use std::cell::{Cell, RefCell};
56 use std::{cmp, fmt, iter, ptr};
57 use std::collections::BTreeSet;
58 use rustc_data_structures::ptr_key::PtrKey;
59 use rustc_data_structures::sync::Lrc;
60 use rustc_data_structures::fx::FxIndexMap;
62 use diagnostics::{Suggestion, ImportSuggestion};
63 use diagnostics::{find_span_of_binding_until_next_binding, extend_span_to_previous_binding};
64 use late::{HasGenericParams, PathSource, Rib, RibKind::*};
65 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
66 use macros::{LegacyBinding, LegacyScope};
68 type Res = def::Res<NodeId>;
75 mod build_reduced_graph;
78 const KNOWN_TOOLS: &[Name] = &[sym::clippy, sym::rustfmt];
85 #[derive(Copy, Clone, PartialEq, Debug)]
86 pub enum Determinacy {
92 fn determined(determined: bool) -> Determinacy {
93 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
97 /// A specific scope in which a name can be looked up.
98 /// This enum is currently used only for early resolution (imports and macros),
99 /// but not for late resolution yet.
100 #[derive(Clone, Copy)]
103 MacroRules(LegacyScope<'a>),
115 /// Names from different contexts may want to visit different subsets of all specific scopes
116 /// with different restrictions when looking up the resolution.
117 /// This enum is currently used only for early resolution (imports and macros),
118 /// but not for late resolution yet.
120 /// All scopes with the given namespace.
121 All(Namespace, /*is_import*/ bool),
122 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
123 AbsolutePath(Namespace),
124 /// All scopes with macro namespace and the given macro kind restriction.
128 /// Everything you need to know about a name's location to resolve it.
129 /// Serves as a starting point for the scope visitor.
130 /// This struct is currently used only for early resolution (imports and macros),
131 /// but not for late resolution yet.
132 #[derive(Clone, Copy, Debug)]
133 pub struct ParentScope<'a> {
136 legacy: LegacyScope<'a>,
137 derives: &'a [ast::Path],
140 impl<'a> ParentScope<'a> {
141 /// Creates a parent scope with the passed argument used as the module scope component,
142 /// and other scope components set to default empty values.
143 pub fn module(module: Module<'a>) -> ParentScope<'a> {
146 expansion: ExpnId::root(),
147 legacy: LegacyScope::Empty,
154 struct BindingError {
156 origin: BTreeSet<Span>,
157 target: BTreeSet<Span>,
161 impl PartialOrd for BindingError {
162 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
163 Some(self.cmp(other))
167 impl PartialEq for BindingError {
168 fn eq(&self, other: &BindingError) -> bool {
169 self.name == other.name
173 impl Ord for BindingError {
174 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
175 self.name.cmp(&other.name)
179 enum ResolutionError<'a> {
180 /// Error E0401: can't use type or const parameters from outer function.
181 GenericParamsFromOuterFunction(Res, HasGenericParams),
182 /// Error E0403: the name is already used for a type or const parameter in this generic
184 NameAlreadyUsedInParameterList(Name, Span),
185 /// Error E0407: method is not a member of trait.
186 MethodNotMemberOfTrait(Name, &'a str),
187 /// Error E0437: type is not a member of trait.
188 TypeNotMemberOfTrait(Name, &'a str),
189 /// Error E0438: const is not a member of trait.
190 ConstNotMemberOfTrait(Name, &'a str),
191 /// Error E0408: variable `{}` is not bound in all patterns.
192 VariableNotBoundInPattern(&'a BindingError),
193 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
194 VariableBoundWithDifferentMode(Name, Span),
195 /// Error E0415: identifier is bound more than once in this parameter list.
196 IdentifierBoundMoreThanOnceInParameterList(&'a str),
197 /// Error E0416: identifier is bound more than once in the same pattern.
198 IdentifierBoundMoreThanOnceInSamePattern(&'a str),
199 /// Error E0426: use of undeclared label.
200 UndeclaredLabel(&'a str, Option<Name>),
201 /// Error E0429: `self` imports are only allowed within a `{ }` list.
202 SelfImportsOnlyAllowedWithin,
203 /// Error E0430: `self` import can only appear once in the list.
204 SelfImportCanOnlyAppearOnceInTheList,
205 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
206 SelfImportOnlyInImportListWithNonEmptyPrefix,
207 /// Error E0433: failed to resolve.
208 FailedToResolve { label: String, suggestion: Option<Suggestion> },
209 /// Error E0434: can't capture dynamic environment in a fn item.
210 CannotCaptureDynamicEnvironmentInFnItem,
211 /// Error E0435: attempt to use a non-constant value in a constant.
212 AttemptToUseNonConstantValueInConstant,
213 /// Error E0530: `X` bindings cannot shadow `Y`s.
214 BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
215 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
216 ForwardDeclaredTyParam, // FIXME(const_generics:defaults)
217 /// Error E0735: type parameters with a default cannot use `Self`
218 SelfInTyParamDefault,
219 /// Error E0671: const parameter cannot depend on type parameter.
220 ConstParamDependentOnTypeParam,
223 // A minimal representation of a path segment. We use this in resolve because
224 // we synthesize 'path segments' which don't have the rest of an AST or HIR
226 #[derive(Clone, Copy, Debug)]
233 fn from_path(path: &Path) -> Vec<Segment> {
234 path.segments.iter().map(|s| s.into()).collect()
237 fn from_ident(ident: Ident) -> Segment {
244 fn names_to_string(segments: &[Segment]) -> String {
245 names_to_string(&segments.iter()
246 .map(|seg| seg.ident.name)
247 .collect::<Vec<_>>())
251 impl<'a> From<&'a ast::PathSegment> for Segment {
252 fn from(seg: &'a ast::PathSegment) -> Segment {
260 struct UsePlacementFinder {
261 target_module: NodeId,
266 impl UsePlacementFinder {
267 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
268 let mut finder = UsePlacementFinder {
273 visit::walk_crate(&mut finder, krate);
274 (finder.span, finder.found_use)
278 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
281 module: &'tcx ast::Mod,
283 _: &[ast::Attribute],
286 if self.span.is_some() {
289 if node_id != self.target_module {
290 visit::walk_mod(self, module);
293 // find a use statement
294 for item in &module.items {
296 ItemKind::Use(..) => {
297 // don't suggest placing a use before the prelude
298 // import or other generated ones
299 if !item.span.from_expansion() {
300 self.span = Some(item.span.shrink_to_lo());
301 self.found_use = true;
305 // don't place use before extern crate
306 ItemKind::ExternCrate(_) => {}
307 // but place them before the first other item
308 _ => if self.span.map_or(true, |span| item.span < span ) {
309 if !item.span.from_expansion() {
310 // don't insert between attributes and an item
311 if item.attrs.is_empty() {
312 self.span = Some(item.span.shrink_to_lo());
314 // find the first attribute on the item
315 for attr in &item.attrs {
316 if self.span.map_or(true, |span| attr.span < span) {
317 self.span = Some(attr.span.shrink_to_lo());
328 /// An intermediate resolution result.
330 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
331 /// items are visible in their whole block, while `Res`es only from the place they are defined
334 enum LexicalScopeBinding<'a> {
335 Item(&'a NameBinding<'a>),
339 impl<'a> LexicalScopeBinding<'a> {
340 fn item(self) -> Option<&'a NameBinding<'a>> {
342 LexicalScopeBinding::Item(binding) => Some(binding),
347 fn res(self) -> Res {
349 LexicalScopeBinding::Item(binding) => binding.res(),
350 LexicalScopeBinding::Res(res) => res,
355 #[derive(Copy, Clone, Debug)]
356 enum ModuleOrUniformRoot<'a> {
360 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
361 CrateRootAndExternPrelude,
363 /// Virtual module that denotes resolution in extern prelude.
364 /// Used for paths starting with `::` on 2018 edition.
367 /// Virtual module that denotes resolution in current scope.
368 /// Used only for resolving single-segment imports. The reason it exists is that import paths
369 /// are always split into two parts, the first of which should be some kind of module.
373 impl ModuleOrUniformRoot<'_> {
374 fn same_def(lhs: Self, rhs: Self) -> bool {
376 (ModuleOrUniformRoot::Module(lhs),
377 ModuleOrUniformRoot::Module(rhs)) => lhs.def_id() == rhs.def_id(),
378 (ModuleOrUniformRoot::CrateRootAndExternPrelude,
379 ModuleOrUniformRoot::CrateRootAndExternPrelude) |
380 (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) |
381 (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
387 #[derive(Clone, Debug)]
388 enum PathResult<'a> {
389 Module(ModuleOrUniformRoot<'a>),
390 NonModule(PartialRes),
395 suggestion: Option<Suggestion>,
396 is_error_from_last_segment: bool,
401 /// An anonymous module; e.g., just a block.
406 /// { // This is an anonymous module
407 /// f(); // This resolves to (2) as we are inside the block.
410 /// f(); // Resolves to (1)
414 /// Any module with a name.
418 /// * A normal module ‒ either `mod from_file;` or `mod from_block { }`.
419 /// * A trait or an enum (it implicitly contains associated types, methods and variant
421 Def(DefKind, DefId, Name),
425 /// Get name of the module.
426 pub fn name(&self) -> Option<Name> {
428 ModuleKind::Block(..) => None,
429 ModuleKind::Def(.., name) => Some(*name),
434 type Resolutions<'a> = RefCell<FxIndexMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>;
436 /// One node in the tree of modules.
437 pub struct ModuleData<'a> {
438 parent: Option<Module<'a>>,
441 // The def id of the closest normal module (`mod`) ancestor (including this module).
442 normal_ancestor_id: DefId,
444 // Mapping between names and their (possibly in-progress) resolutions in this module.
445 // Resolutions in modules from other crates are not populated until accessed.
446 lazy_resolutions: Resolutions<'a>,
447 // True if this is a module from other crate that needs to be populated on access.
448 populate_on_access: Cell<bool>,
450 // Macro invocations that can expand into items in this module.
451 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
453 no_implicit_prelude: bool,
455 glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
456 globs: RefCell<Vec<&'a ImportDirective<'a>>>,
458 // Used to memoize the traits in this module for faster searches through all traits in scope.
459 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
461 /// Span of the module itself. Used for error reporting.
467 type Module<'a> = &'a ModuleData<'a>;
469 impl<'a> ModuleData<'a> {
470 fn new(parent: Option<Module<'a>>,
472 normal_ancestor_id: DefId,
474 span: Span) -> Self {
479 lazy_resolutions: Default::default(),
480 populate_on_access: Cell::new(!normal_ancestor_id.is_local()),
481 unexpanded_invocations: Default::default(),
482 no_implicit_prelude: false,
483 glob_importers: RefCell::new(Vec::new()),
484 globs: RefCell::new(Vec::new()),
485 traits: RefCell::new(None),
491 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
492 where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
494 for (&(ident, ns), name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
495 name_resolution.borrow().binding.map(|binding| f(resolver, ident, ns, binding));
499 fn res(&self) -> Option<Res> {
501 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
506 fn def_id(&self) -> Option<DefId> {
508 ModuleKind::Def(_, def_id, _) => Some(def_id),
513 // `self` resolves to the first module ancestor that `is_normal`.
514 fn is_normal(&self) -> bool {
516 ModuleKind::Def(DefKind::Mod, _, _) => true,
521 fn is_trait(&self) -> bool {
523 ModuleKind::Def(DefKind::Trait, _, _) => true,
528 fn nearest_item_scope(&'a self) -> Module<'a> {
530 ModuleKind::Def(DefKind::Enum, ..) | ModuleKind::Def(DefKind::Trait, ..) =>
531 self.parent.expect("enum or trait module without a parent"),
536 fn is_ancestor_of(&self, mut other: &Self) -> bool {
537 while !ptr::eq(self, other) {
538 if let Some(parent) = other.parent {
548 impl<'a> fmt::Debug for ModuleData<'a> {
549 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
550 write!(f, "{:?}", self.res())
554 /// Records a possibly-private value, type, or module definition.
555 #[derive(Clone, Debug)]
556 pub struct NameBinding<'a> {
557 kind: NameBindingKind<'a>,
558 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
564 pub trait ToNameBinding<'a> {
565 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
568 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
569 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
574 #[derive(Clone, Debug)]
575 enum NameBindingKind<'a> {
576 Res(Res, /* is_macro_export */ bool),
579 binding: &'a NameBinding<'a>,
580 directive: &'a ImportDirective<'a>,
585 impl<'a> NameBindingKind<'a> {
586 /// Is this a name binding of a import?
587 fn is_import(&self) -> bool {
589 NameBindingKind::Import { .. } => true,
595 struct PrivacyError<'a>(Span, Ident, &'a NameBinding<'a>);
597 struct UseError<'a> {
598 err: DiagnosticBuilder<'a>,
599 /// Attach `use` statements for these candidates.
600 candidates: Vec<ImportSuggestion>,
601 /// The `NodeId` of the module to place the use-statements in.
603 /// Whether the diagnostic should state that it's "better".
607 #[derive(Clone, Copy, PartialEq, Debug)]
612 LegacyHelperVsPrelude,
621 fn descr(self) -> &'static str {
623 AmbiguityKind::Import =>
624 "name vs any other name during import resolution",
625 AmbiguityKind::BuiltinAttr =>
626 "built-in attribute vs any other name",
627 AmbiguityKind::DeriveHelper =>
628 "derive helper attribute vs any other name",
629 AmbiguityKind::LegacyHelperVsPrelude =>
630 "legacy plugin helper attribute vs name from prelude",
631 AmbiguityKind::LegacyVsModern =>
632 "`macro_rules` vs non-`macro_rules` from other module",
633 AmbiguityKind::GlobVsOuter =>
634 "glob import vs any other name from outer scope during import/macro resolution",
635 AmbiguityKind::GlobVsGlob =>
636 "glob import vs glob import in the same module",
637 AmbiguityKind::GlobVsExpanded =>
638 "glob import vs macro-expanded name in the same \
639 module during import/macro resolution",
640 AmbiguityKind::MoreExpandedVsOuter =>
641 "macro-expanded name vs less macro-expanded name \
642 from outer scope during import/macro resolution",
647 /// Miscellaneous bits of metadata for better ambiguity error reporting.
648 #[derive(Clone, Copy, PartialEq)]
649 enum AmbiguityErrorMisc {
656 struct AmbiguityError<'a> {
659 b1: &'a NameBinding<'a>,
660 b2: &'a NameBinding<'a>,
661 misc1: AmbiguityErrorMisc,
662 misc2: AmbiguityErrorMisc,
665 impl<'a> NameBinding<'a> {
666 fn module(&self) -> Option<Module<'a>> {
668 NameBindingKind::Module(module) => Some(module),
669 NameBindingKind::Import { binding, .. } => binding.module(),
674 fn res(&self) -> Res {
676 NameBindingKind::Res(res, _) => res,
677 NameBindingKind::Module(module) => module.res().unwrap(),
678 NameBindingKind::Import { binding, .. } => binding.res(),
682 fn is_ambiguity(&self) -> bool {
683 self.ambiguity.is_some() || match self.kind {
684 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
689 // We sometimes need to treat variants as `pub` for backwards compatibility.
690 fn pseudo_vis(&self) -> ty::Visibility {
691 if self.is_variant() && self.res().def_id().is_local() {
692 ty::Visibility::Public
698 fn is_variant(&self) -> bool {
700 NameBindingKind::Res(Res::Def(DefKind::Variant, _), _) |
701 NameBindingKind::Res(Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _), _) => true,
706 fn is_extern_crate(&self) -> bool {
708 NameBindingKind::Import {
709 directive: &ImportDirective {
710 subclass: ImportDirectiveSubclass::ExternCrate { .. }, ..
713 NameBindingKind::Module(
714 &ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }
715 ) => def_id.index == CRATE_DEF_INDEX,
720 fn is_import(&self) -> bool {
722 NameBindingKind::Import { .. } => true,
727 fn is_glob_import(&self) -> bool {
729 NameBindingKind::Import { directive, .. } => directive.is_glob(),
734 fn is_importable(&self) -> bool {
736 Res::Def(DefKind::AssocConst, _)
737 | Res::Def(DefKind::Method, _)
738 | Res::Def(DefKind::AssocTy, _) => false,
743 fn is_macro_def(&self) -> bool {
745 NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
750 fn macro_kind(&self) -> Option<MacroKind> {
751 self.res().macro_kind()
754 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
755 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
756 // Then this function returns `true` if `self` may emerge from a macro *after* that
757 // in some later round and screw up our previously found resolution.
758 // See more detailed explanation in
759 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
760 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
761 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
762 // Expansions are partially ordered, so "may appear after" is an inversion of
763 // "certainly appears before or simultaneously" and includes unordered cases.
764 let self_parent_expansion = self.expansion;
765 let other_parent_expansion = binding.expansion;
766 let certainly_before_other_or_simultaneously =
767 other_parent_expansion.is_descendant_of(self_parent_expansion);
768 let certainly_before_invoc_or_simultaneously =
769 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
770 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
774 /// Interns the names of the primitive types.
776 /// All other types are defined somewhere and possibly imported, but the primitive ones need
777 /// special handling, since they have no place of origin.
778 struct PrimitiveTypeTable {
779 primitive_types: FxHashMap<Name, PrimTy>,
782 impl PrimitiveTypeTable {
783 fn new() -> PrimitiveTypeTable {
784 let mut table = FxHashMap::default();
786 table.insert(sym::bool, Bool);
787 table.insert(sym::char, Char);
788 table.insert(sym::f32, Float(FloatTy::F32));
789 table.insert(sym::f64, Float(FloatTy::F64));
790 table.insert(sym::isize, Int(IntTy::Isize));
791 table.insert(sym::i8, Int(IntTy::I8));
792 table.insert(sym::i16, Int(IntTy::I16));
793 table.insert(sym::i32, Int(IntTy::I32));
794 table.insert(sym::i64, Int(IntTy::I64));
795 table.insert(sym::i128, Int(IntTy::I128));
796 table.insert(sym::str, Str);
797 table.insert(sym::usize, Uint(UintTy::Usize));
798 table.insert(sym::u8, Uint(UintTy::U8));
799 table.insert(sym::u16, Uint(UintTy::U16));
800 table.insert(sym::u32, Uint(UintTy::U32));
801 table.insert(sym::u64, Uint(UintTy::U64));
802 table.insert(sym::u128, Uint(UintTy::U128));
803 Self { primitive_types: table }
807 #[derive(Debug, Default, Clone)]
808 pub struct ExternPreludeEntry<'a> {
809 extern_crate_item: Option<&'a NameBinding<'a>>,
810 pub introduced_by_item: bool,
813 /// The main resolver class.
815 /// This is the visitor that walks the whole crate.
816 pub struct Resolver<'a> {
817 session: &'a Session,
820 pub definitions: Definitions,
822 pub graph_root: Module<'a>,
824 prelude: Option<Module<'a>>,
825 pub extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
827 /// N.B., this is used only for better diagnostics, not name resolution itself.
828 has_self: FxHashSet<DefId>,
830 /// Names of fields of an item `DefId` accessible with dot syntax.
831 /// Used for hints during error reporting.
832 field_names: FxHashMap<DefId, Vec<Spanned<Name>>>,
834 /// All imports known to succeed or fail.
835 determined_imports: Vec<&'a ImportDirective<'a>>,
837 /// All non-determined imports.
838 indeterminate_imports: Vec<&'a ImportDirective<'a>>,
840 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
841 /// We are resolving a last import segment during import validation.
842 last_import_segment: bool,
843 /// This binding should be ignored during in-module resolution, so that we don't get
844 /// "self-confirming" import resolutions during import validation.
845 blacklisted_binding: Option<&'a NameBinding<'a>>,
847 /// The idents for the primitive types.
848 primitive_type_table: PrimitiveTypeTable,
850 /// Resolutions for nodes that have a single resolution.
851 partial_res_map: NodeMap<PartialRes>,
852 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
853 import_res_map: NodeMap<PerNS<Option<Res>>>,
854 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
855 label_res_map: NodeMap<NodeId>,
857 pub export_map: ExportMap<NodeId>,
858 pub trait_map: TraitMap,
860 /// A map from nodes to anonymous modules.
861 /// Anonymous modules are pseudo-modules that are implicitly created around items
862 /// contained within blocks.
864 /// For example, if we have this:
872 /// There will be an anonymous module created around `g` with the ID of the
873 /// entry block for `f`.
874 block_map: NodeMap<Module<'a>>,
875 /// A fake module that contains no definition and no prelude. Used so that
876 /// some AST passes can generate identifiers that only resolve to local or
878 empty_module: Module<'a>,
879 module_map: FxHashMap<DefId, Module<'a>>,
880 extern_module_map: FxHashMap<(DefId, bool /* MacrosOnly? */), Module<'a>>,
881 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
883 /// Maps glob imports to the names of items actually imported.
884 pub glob_map: GlobMap,
886 used_imports: FxHashSet<(NodeId, Namespace)>,
887 pub maybe_unused_trait_imports: NodeSet,
888 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
890 /// Privacy errors are delayed until the end in order to deduplicate them.
891 privacy_errors: Vec<PrivacyError<'a>>,
892 /// Ambiguity errors are delayed for deduplication.
893 ambiguity_errors: Vec<AmbiguityError<'a>>,
894 /// `use` injections are delayed for better placement and deduplication.
895 use_injections: Vec<UseError<'a>>,
896 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
897 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
899 arenas: &'a ResolverArenas<'a>,
900 dummy_binding: &'a NameBinding<'a>,
902 crate_loader: &'a mut CrateLoader<'a>,
903 macro_names: FxHashSet<Ident>,
904 builtin_macros: FxHashMap<Name, SyntaxExtension>,
905 macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
906 pub all_macros: FxHashMap<Name, Res>,
907 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
908 dummy_ext_bang: Lrc<SyntaxExtension>,
909 dummy_ext_derive: Lrc<SyntaxExtension>,
910 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
911 macro_defs: FxHashMap<ExpnId, DefId>,
912 local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
913 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
914 unused_macros: NodeMap<Span>,
915 proc_macro_stubs: NodeSet,
916 /// Traces collected during macro resolution and validated when it's complete.
917 single_segment_macro_resolutions: Vec<(Ident, MacroKind, ParentScope<'a>,
918 Option<&'a NameBinding<'a>>)>,
919 multi_segment_macro_resolutions: Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>,
921 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
922 /// Some built-in derives mark items they are applied to so they are treated specially later.
923 /// Derive macros cannot modify the item themselves and have to store the markers in the global
924 /// context, so they attach the markers to derive container IDs using this resolver table.
925 /// FIXME: Find a way for `PartialEq` and `Eq` to emulate `#[structural_match]`
926 /// by marking the produced impls rather than the original items.
927 special_derives: FxHashMap<ExpnId, SpecialDerives>,
928 /// Parent scopes in which the macros were invoked.
929 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
930 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
931 /// Legacy scopes *produced* by expanding the macro invocations,
932 /// include all the `macro_rules` items and other invocations generated by them.
933 output_legacy_scopes: FxHashMap<ExpnId, LegacyScope<'a>>,
935 /// Avoid duplicated errors for "name already defined".
936 name_already_seen: FxHashMap<Name, Span>,
938 potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
940 /// Table for mapping struct IDs into struct constructor IDs,
941 /// it's not used during normal resolution, only for better error reporting.
942 struct_constructors: DefIdMap<(Res, ty::Visibility)>,
944 /// Features enabled for this crate.
945 active_features: FxHashSet<Name>,
947 /// Stores enum visibilities to properly build a reduced graph
948 /// when visiting the correspondent variants.
949 variant_vis: DefIdMap<ty::Visibility>,
952 /// Nothing really interesting here; it just provides memory for the rest of the crate.
954 pub struct ResolverArenas<'a> {
955 modules: arena::TypedArena<ModuleData<'a>>,
956 local_modules: RefCell<Vec<Module<'a>>>,
957 name_bindings: arena::TypedArena<NameBinding<'a>>,
958 import_directives: arena::TypedArena<ImportDirective<'a>>,
959 name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
960 legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
961 ast_paths: arena::TypedArena<ast::Path>,
964 impl<'a> ResolverArenas<'a> {
965 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
966 let module = self.modules.alloc(module);
967 if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
968 self.local_modules.borrow_mut().push(module);
972 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
973 self.local_modules.borrow()
975 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
976 self.name_bindings.alloc(name_binding)
978 fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
979 -> &'a ImportDirective<'_> {
980 self.import_directives.alloc(import_directive)
982 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
983 self.name_resolutions.alloc(Default::default())
985 fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
986 self.legacy_bindings.alloc(binding)
988 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
989 self.ast_paths.alloc_from_iter(paths.iter().cloned())
993 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
994 fn as_mut(&mut self) -> &mut Resolver<'a> { self }
997 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
998 fn parent(self, id: DefId) -> Option<DefId> {
1000 LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1001 _ => self.cstore.def_key(id).parent,
1002 }.map(|index| DefId { index, ..id })
1006 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1007 /// the resolver is no longer needed as all the relevant information is inline.
1008 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1009 fn resolve_str_path(
1012 crate_root: Option<Name>,
1013 components: &[Name],
1015 ) -> (ast::Path, Res) {
1016 let root = if crate_root.is_some() {
1021 let segments = iter::once(Ident::with_dummy_span(root))
1023 crate_root.into_iter()
1024 .chain(components.iter().cloned())
1025 .map(Ident::with_dummy_span)
1026 ).map(|i| self.new_ast_path_segment(i)).collect::<Vec<_>>();
1028 let path = ast::Path {
1033 let parent_scope = &ParentScope::module(self.graph_root);
1034 let res = match self.resolve_ast_path(&path, ns, parent_scope) {
1036 Err((span, error)) => {
1037 self.report_error(span, error);
1044 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1045 self.partial_res_map.get(&id).cloned()
1048 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1049 self.import_res_map.get(&id).cloned().unwrap_or_default()
1052 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1053 self.label_res_map.get(&id).cloned()
1056 fn definitions(&mut self) -> &mut Definitions {
1057 &mut self.definitions
1060 fn has_derives(&self, node_id: NodeId, derives: SpecialDerives) -> bool {
1061 let def_id = self.definitions.local_def_id(node_id);
1062 let expn_id = self.definitions.expansion_that_defined(def_id.index);
1063 self.has_derives(expn_id, derives)
1067 impl<'a> Resolver<'a> {
1068 pub fn new(session: &'a Session,
1072 crate_loader: &'a mut CrateLoader<'a>,
1073 arenas: &'a ResolverArenas<'a>)
1075 let root_def_id = DefId::local(CRATE_DEF_INDEX);
1076 let root_module_kind = ModuleKind::Def(
1081 let graph_root = arenas.alloc_module(ModuleData {
1082 no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
1083 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1085 let empty_module_kind = ModuleKind::Def(
1090 let empty_module = arenas.alloc_module(ModuleData {
1091 no_implicit_prelude: true,
1100 let mut module_map = FxHashMap::default();
1101 module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1103 let mut definitions = Definitions::default();
1104 definitions.create_root_def(crate_name, session.local_crate_disambiguator());
1106 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> =
1107 session.opts.externs.iter().map(|kv| (Ident::from_str(kv.0), Default::default()))
1110 if !attr::contains_name(&krate.attrs, sym::no_core) {
1111 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1112 if !attr::contains_name(&krate.attrs, sym::no_std) {
1113 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1114 if session.rust_2018() {
1115 extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default());
1120 let mut invocation_parent_scopes = FxHashMap::default();
1121 invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root));
1123 let mut macro_defs = FxHashMap::default();
1124 macro_defs.insert(ExpnId::root(), root_def_id);
1126 let features = session.features_untracked();
1127 let non_macro_attr =
1128 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1137 // The outermost module has def ID 0; this is not reflected in the
1143 has_self: FxHashSet::default(),
1144 field_names: FxHashMap::default(),
1146 determined_imports: Vec::new(),
1147 indeterminate_imports: Vec::new(),
1149 last_import_segment: false,
1150 blacklisted_binding: None,
1152 primitive_type_table: PrimitiveTypeTable::new(),
1154 partial_res_map: Default::default(),
1155 import_res_map: Default::default(),
1156 label_res_map: Default::default(),
1157 export_map: FxHashMap::default(),
1158 trait_map: Default::default(),
1161 block_map: Default::default(),
1162 extern_module_map: FxHashMap::default(),
1163 binding_parent_modules: FxHashMap::default(),
1164 ast_transform_scopes: FxHashMap::default(),
1166 glob_map: Default::default(),
1168 used_imports: FxHashSet::default(),
1169 maybe_unused_trait_imports: Default::default(),
1170 maybe_unused_extern_crates: Vec::new(),
1172 privacy_errors: Vec::new(),
1173 ambiguity_errors: Vec::new(),
1174 use_injections: Vec::new(),
1175 macro_expanded_macro_export_errors: BTreeSet::new(),
1178 dummy_binding: arenas.alloc_name_binding(NameBinding {
1179 kind: NameBindingKind::Res(Res::Err, false),
1181 expansion: ExpnId::root(),
1183 vis: ty::Visibility::Public,
1187 macro_names: FxHashSet::default(),
1188 builtin_macros: Default::default(),
1189 macro_use_prelude: FxHashMap::default(),
1190 all_macros: FxHashMap::default(),
1191 macro_map: FxHashMap::default(),
1192 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1193 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1194 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1195 invocation_parent_scopes,
1196 output_legacy_scopes: Default::default(),
1198 local_macro_def_scopes: FxHashMap::default(),
1199 name_already_seen: FxHashMap::default(),
1200 potentially_unused_imports: Vec::new(),
1201 struct_constructors: Default::default(),
1202 unused_macros: Default::default(),
1203 proc_macro_stubs: Default::default(),
1204 single_segment_macro_resolutions: Default::default(),
1205 multi_segment_macro_resolutions: Default::default(),
1206 builtin_attrs: Default::default(),
1207 special_derives: Default::default(),
1209 features.declared_lib_features.iter().map(|(feat, ..)| *feat)
1210 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1212 variant_vis: Default::default()
1216 pub fn arenas() -> ResolverArenas<'a> {
1220 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1221 self.non_macro_attrs[mark_used as usize].clone()
1224 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1226 MacroKind::Bang => self.dummy_ext_bang.clone(),
1227 MacroKind::Derive => self.dummy_ext_derive.clone(),
1228 MacroKind::Attr => self.non_macro_attr(true),
1232 /// Runs the function on each namespace.
1233 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1239 fn is_builtin_macro(&mut self, res: Res) -> bool {
1240 self.get_macro(res).map_or(false, |ext| ext.is_builtin)
1243 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1245 match self.macro_defs.get(&ctxt.outer_expn()) {
1246 Some(&def_id) => return def_id,
1247 None => ctxt.remove_mark(),
1252 fn has_derives(&self, expn_id: ExpnId, markers: SpecialDerives) -> bool {
1253 self.special_derives.get(&expn_id).map_or(false, |m| m.contains(markers))
1256 /// Entry point to crate resolution.
1257 pub fn resolve_crate(&mut self, krate: &Crate) {
1259 self.session.prof.generic_activity("resolve_crate");
1261 ImportResolver { r: self }.finalize_imports();
1262 self.finalize_macro_resolutions();
1264 self.late_resolve_crate(krate);
1266 self.check_unused(krate);
1267 self.report_errors(krate);
1268 self.crate_loader.postprocess(krate);
1275 normal_ancestor_id: DefId,
1279 let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span);
1280 self.arenas.alloc_module(module)
1283 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1284 if module.populate_on_access.get() {
1285 module.populate_on_access.set(false);
1286 self.build_reduced_graph_external(module);
1288 &module.lazy_resolutions
1291 fn resolution(&mut self, module: Module<'a>, ident: Ident, ns: Namespace)
1292 -> &'a RefCell<NameResolution<'a>> {
1293 *self.resolutions(module).borrow_mut().entry((ident.modern(), ns))
1294 .or_insert_with(|| self.arenas.alloc_name_resolution())
1297 fn record_use(&mut self, ident: Ident, ns: Namespace,
1298 used_binding: &'a NameBinding<'a>, is_lexical_scope: bool) {
1299 if let Some((b2, kind)) = used_binding.ambiguity {
1300 self.ambiguity_errors.push(AmbiguityError {
1301 kind, ident, b1: used_binding, b2,
1302 misc1: AmbiguityErrorMisc::None,
1303 misc2: AmbiguityErrorMisc::None,
1306 if let NameBindingKind::Import { directive, binding, ref used } = used_binding.kind {
1307 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1308 // but not introduce it, as used if they are accessed from lexical scope.
1309 if is_lexical_scope {
1310 if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
1311 if let Some(crate_item) = entry.extern_crate_item {
1312 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1319 directive.used.set(true);
1320 self.used_imports.insert((directive.id, ns));
1321 self.add_to_glob_map(&directive, ident);
1322 self.record_use(ident, ns, binding, false);
1327 fn add_to_glob_map(&mut self, directive: &ImportDirective<'_>, ident: Ident) {
1328 if directive.is_glob() {
1329 self.glob_map.entry(directive.id).or_default().insert(ident.name);
1333 /// A generic scope visitor.
1334 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1335 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1338 scope_set: ScopeSet,
1339 parent_scope: &ParentScope<'a>,
1341 mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>,
1343 // General principles:
1344 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1345 // built into the language or standard library. This way we can add new names into the
1346 // language or standard library without breaking user code.
1347 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1348 // Places to search (in order of decreasing priority):
1350 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1351 // (open set, not controlled).
1352 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1353 // (open, not controlled).
1354 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1355 // 4. Tool modules (closed, controlled right now, but not in the future).
1356 // 5. Standard library prelude (de-facto closed, controlled).
1357 // 6. Language prelude (closed, controlled).
1359 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1360 // (open set, not controlled).
1361 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1362 // (open, not controlled).
1363 // 3. Standard library prelude (de-facto closed, controlled).
1365 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1366 // are currently reported as errors. They should be higher in priority than preludes
1367 // and probably even names in modules according to the "general principles" above. They
1368 // also should be subject to restricted shadowing because are effectively produced by
1369 // derives (you need to resolve the derive first to add helpers into scope), but they
1370 // should be available before the derive is expanded for compatibility.
1371 // It's mess in general, so we are being conservative for now.
1372 // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
1373 // priority than prelude macros, but create ambiguities with macros in modules.
1374 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1375 // (open, not controlled). Have higher priority than prelude macros, but create
1376 // ambiguities with `macro_rules`.
1377 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1378 // 4a. User-defined prelude from macro-use
1379 // (open, the open part is from macro expansions, not controlled).
1380 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1381 // 4c. Standard library prelude (de-facto closed, controlled).
1382 // 6. Language prelude: builtin attributes (closed, controlled).
1383 // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
1384 // but introduced by legacy plugins using `register_attribute`. Priority is somewhere
1385 // in prelude, not sure where exactly (creates ambiguities with any other prelude names).
1387 let rust_2015 = ident.span.rust_2015();
1388 let (ns, is_absolute_path) = match scope_set {
1389 ScopeSet::All(ns, _) => (ns, false),
1390 ScopeSet::AbsolutePath(ns) => (ns, true),
1391 ScopeSet::Macro(_) => (MacroNS, false),
1393 // Jump out of trait or enum modules, they do not act as scopes.
1394 let module = parent_scope.module.nearest_item_scope();
1395 let mut scope = match ns {
1396 _ if is_absolute_path => Scope::CrateRoot,
1397 TypeNS | ValueNS => Scope::Module(module),
1398 MacroNS => Scope::DeriveHelpers,
1400 let mut ident = ident.modern();
1401 let mut use_prelude = !module.no_implicit_prelude;
1404 let visit = match scope {
1405 Scope::DeriveHelpers => true,
1406 Scope::MacroRules(..) => true,
1407 Scope::CrateRoot => true,
1408 Scope::Module(..) => true,
1409 Scope::MacroUsePrelude => use_prelude || rust_2015,
1410 Scope::BuiltinAttrs => true,
1411 Scope::LegacyPluginHelpers => use_prelude || rust_2015,
1412 Scope::ExternPrelude => use_prelude || is_absolute_path,
1413 Scope::ToolPrelude => use_prelude,
1414 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1415 Scope::BuiltinTypes => true,
1419 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) {
1420 return break_result;
1424 scope = match scope {
1425 Scope::DeriveHelpers =>
1426 Scope::MacroRules(parent_scope.legacy),
1427 Scope::MacroRules(legacy_scope) => match legacy_scope {
1428 LegacyScope::Binding(binding) => Scope::MacroRules(
1429 binding.parent_legacy_scope
1431 LegacyScope::Invocation(invoc_id) => Scope::MacroRules(
1432 self.output_legacy_scopes.get(&invoc_id).cloned()
1433 .unwrap_or(self.invocation_parent_scopes[&invoc_id].legacy)
1435 LegacyScope::Empty => Scope::Module(module),
1437 Scope::CrateRoot => match ns {
1439 ident.span.adjust(ExpnId::root());
1440 Scope::ExternPrelude
1442 ValueNS | MacroNS => break,
1444 Scope::Module(module) => {
1445 use_prelude = !module.no_implicit_prelude;
1446 match self.hygienic_lexical_parent(module, &mut ident.span) {
1447 Some(parent_module) => Scope::Module(parent_module),
1449 ident.span.adjust(ExpnId::root());
1451 TypeNS => Scope::ExternPrelude,
1452 ValueNS => Scope::StdLibPrelude,
1453 MacroNS => Scope::MacroUsePrelude,
1458 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1459 Scope::BuiltinAttrs => Scope::LegacyPluginHelpers,
1460 Scope::LegacyPluginHelpers => break, // nowhere else to search
1461 Scope::ExternPrelude if is_absolute_path => break,
1462 Scope::ExternPrelude => Scope::ToolPrelude,
1463 Scope::ToolPrelude => Scope::StdLibPrelude,
1464 Scope::StdLibPrelude => match ns {
1465 TypeNS => Scope::BuiltinTypes,
1466 ValueNS => break, // nowhere else to search
1467 MacroNS => Scope::BuiltinAttrs,
1469 Scope::BuiltinTypes => break, // nowhere else to search
1476 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1477 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1478 /// `ident` in the first scope that defines it (or None if no scopes define it).
1480 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1481 /// the items are defined in the block. For example,
1484 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1487 /// g(); // This resolves to the local variable `g` since it shadows the item.
1491 /// Invariant: This must only be called during main resolution, not during
1492 /// import resolution.
1493 fn resolve_ident_in_lexical_scope(&mut self,
1496 parent_scope: &ParentScope<'a>,
1497 record_used_id: Option<NodeId>,
1500 -> Option<LexicalScopeBinding<'a>> {
1501 assert!(ns == TypeNS || ns == ValueNS);
1502 if ident.name == kw::Invalid {
1503 return Some(LexicalScopeBinding::Res(Res::Err));
1505 let (general_span, modern_span) = if ident.name == kw::SelfUpper {
1506 // FIXME(jseyfried) improve `Self` hygiene
1507 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1508 (empty_span, empty_span)
1509 } else if ns == TypeNS {
1510 let modern_span = ident.span.modern();
1511 (modern_span, modern_span)
1513 (ident.span.modern_and_legacy(), ident.span.modern())
1515 ident.span = general_span;
1516 let modern_ident = Ident { span: modern_span, ..ident };
1518 // Walk backwards up the ribs in scope.
1519 let record_used = record_used_id.is_some();
1520 let mut module = self.graph_root;
1521 for i in (0 .. ribs.len()).rev() {
1522 debug!("walk rib\n{:?}", ribs[i].bindings);
1523 // Use the rib kind to determine whether we are resolving parameters
1524 // (modern hygiene) or local variables (legacy hygiene).
1525 let rib_ident = if ribs[i].kind.contains_params() {
1530 if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() {
1531 // The ident resolves to a type parameter or local variable.
1532 return Some(LexicalScopeBinding::Res(
1533 self.validate_res_from_ribs(i, rib_ident, res, record_used, path_span, ribs),
1537 module = match ribs[i].kind {
1538 ModuleRibKind(module) => module,
1539 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1540 // If an invocation of this macro created `ident`, give up on `ident`
1541 // and switch to `ident`'s source from the macro definition.
1542 ident.span.remove_mark();
1549 let item = self.resolve_ident_in_module_unadjusted(
1550 ModuleOrUniformRoot::Module(module),
1557 if let Ok(binding) = item {
1558 // The ident resolves to an item.
1559 return Some(LexicalScopeBinding::Item(binding));
1563 ModuleKind::Block(..) => {}, // We can see through blocks
1568 ident = modern_ident;
1569 let mut poisoned = None;
1571 let opt_module = if let Some(node_id) = record_used_id {
1572 self.hygienic_lexical_parent_with_compatibility_fallback(module, &mut ident.span,
1573 node_id, &mut poisoned)
1575 self.hygienic_lexical_parent(module, &mut ident.span)
1577 module = unwrap_or!(opt_module, break);
1578 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1579 let result = self.resolve_ident_in_module_unadjusted(
1580 ModuleOrUniformRoot::Module(module),
1583 adjusted_parent_scope,
1590 if let Some(node_id) = poisoned {
1591 self.session.buffer_lint_with_diagnostic(
1592 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1593 node_id, ident.span,
1594 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1595 lint::builtin::BuiltinLintDiagnostics::
1596 ProcMacroDeriveResolutionFallback(ident.span),
1599 return Some(LexicalScopeBinding::Item(binding))
1601 Err(Determined) => continue,
1602 Err(Undetermined) =>
1603 span_bug!(ident.span, "undetermined resolution during main resolution pass"),
1607 if !module.no_implicit_prelude {
1608 ident.span.adjust(ExpnId::root());
1610 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1611 return Some(LexicalScopeBinding::Item(binding));
1614 if ns == TypeNS && KNOWN_TOOLS.contains(&ident.name) {
1615 let binding = (Res::ToolMod, ty::Visibility::Public,
1616 DUMMY_SP, ExpnId::root()).to_name_binding(self.arenas);
1617 return Some(LexicalScopeBinding::Item(binding));
1619 if let Some(prelude) = self.prelude {
1620 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1621 ModuleOrUniformRoot::Module(prelude),
1628 return Some(LexicalScopeBinding::Item(binding));
1636 fn hygienic_lexical_parent(&mut self, module: Module<'a>, span: &mut Span)
1637 -> Option<Module<'a>> {
1638 if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1639 return Some(self.macro_def_scope(span.remove_mark()));
1642 if let ModuleKind::Block(..) = module.kind {
1643 return Some(module.parent.unwrap().nearest_item_scope());
1649 fn hygienic_lexical_parent_with_compatibility_fallback(&mut self, module: Module<'a>,
1650 span: &mut Span, node_id: NodeId,
1651 poisoned: &mut Option<NodeId>)
1652 -> Option<Module<'a>> {
1653 if let module @ Some(..) = self.hygienic_lexical_parent(module, span) {
1657 // We need to support the next case under a deprecation warning
1660 // ---- begin: this comes from a proc macro derive
1661 // mod implementation_details {
1662 // // Note that `MyStruct` is not in scope here.
1663 // impl SomeTrait for MyStruct { ... }
1667 // So we have to fall back to the module's parent during lexical resolution in this case.
1668 if let Some(parent) = module.parent {
1669 // Inner module is inside the macro, parent module is outside of the macro.
1670 if module.expansion != parent.expansion &&
1671 module.expansion.is_descendant_of(parent.expansion) {
1672 // The macro is a proc macro derive
1673 if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
1674 if let Some(ext) = self.get_macro_by_def_id(def_id) {
1675 if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
1676 if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1677 *poisoned = Some(node_id);
1678 return module.parent;
1689 fn resolve_ident_in_module(
1691 module: ModuleOrUniformRoot<'a>,
1694 parent_scope: &ParentScope<'a>,
1697 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1698 self.resolve_ident_in_module_ext(
1699 module, ident, ns, parent_scope, record_used, path_span
1700 ).map_err(|(determinacy, _)| determinacy)
1703 fn resolve_ident_in_module_ext(
1705 module: ModuleOrUniformRoot<'a>,
1708 parent_scope: &ParentScope<'a>,
1711 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
1712 let tmp_parent_scope;
1713 let mut adjusted_parent_scope = parent_scope;
1715 ModuleOrUniformRoot::Module(m) => {
1716 if let Some(def) = ident.span.modernize_and_adjust(m.expansion) {
1718 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
1719 adjusted_parent_scope = &tmp_parent_scope;
1722 ModuleOrUniformRoot::ExternPrelude => {
1723 ident.span.modernize_and_adjust(ExpnId::root());
1725 ModuleOrUniformRoot::CrateRootAndExternPrelude |
1726 ModuleOrUniformRoot::CurrentScope => {
1730 let result = self.resolve_ident_in_module_unadjusted_ext(
1731 module, ident, ns, adjusted_parent_scope, false, record_used, path_span,
1736 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
1737 let mut ctxt = ident.span.ctxt();
1738 let mark = if ident.name == kw::DollarCrate {
1739 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
1740 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
1741 // as described in `SyntaxContext::apply_mark`, so we ignore prepended modern marks.
1742 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
1743 // definitions actually produced by `macro` and `macro` definitions produced by
1744 // `macro_rules!`, but at least such configurations are not stable yet.
1745 ctxt = ctxt.modern_and_legacy();
1746 let mut iter = ctxt.marks().into_iter().rev().peekable();
1747 let mut result = None;
1748 // Find the last modern mark from the end if it exists.
1749 while let Some(&(mark, transparency)) = iter.peek() {
1750 if transparency == Transparency::Opaque {
1751 result = Some(mark);
1757 // Then find the last legacy mark from the end if it exists.
1758 for (mark, transparency) in iter {
1759 if transparency == Transparency::SemiTransparent {
1760 result = Some(mark);
1767 ctxt = ctxt.modern();
1768 ctxt.adjust(ExpnId::root())
1770 let module = match mark {
1771 Some(def) => self.macro_def_scope(def),
1772 None => return self.graph_root,
1774 self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
1777 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
1778 let mut module = self.get_module(module.normal_ancestor_id);
1779 while module.span.ctxt().modern() != *ctxt {
1780 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
1781 module = self.get_module(parent.normal_ancestor_id);
1789 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1790 parent_scope: &ParentScope<'a>,
1793 crate_lint: CrateLint,
1794 ) -> PathResult<'a> {
1795 self.resolve_path_with_ribs(
1796 path, opt_ns, parent_scope, record_used, path_span, crate_lint, None
1800 fn resolve_path_with_ribs(
1803 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1804 parent_scope: &ParentScope<'a>,
1807 crate_lint: CrateLint,
1808 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
1809 ) -> PathResult<'a> {
1810 let mut module = None;
1811 let mut allow_super = true;
1812 let mut second_binding = None;
1815 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
1816 path_span={:?}, crate_lint={:?})",
1824 for (i, &Segment { ident, id }) in path.iter().enumerate() {
1825 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
1826 let record_segment_res = |this: &mut Self, res| {
1828 if let Some(id) = id {
1829 if !this.partial_res_map.contains_key(&id) {
1830 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
1831 this.record_partial_res(id, PartialRes::new(res));
1837 let is_last = i == path.len() - 1;
1838 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
1839 let name = ident.name;
1841 allow_super &= ns == TypeNS &&
1842 (name == kw::SelfLower ||
1846 if allow_super && name == kw::Super {
1847 let mut ctxt = ident.span.ctxt().modern();
1848 let self_module = match i {
1849 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
1851 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
1855 if let Some(self_module) = self_module {
1856 if let Some(parent) = self_module.parent {
1857 module = Some(ModuleOrUniformRoot::Module(
1858 self.resolve_self(&mut ctxt, parent)));
1862 let msg = "there are too many initial `super`s.".to_string();
1863 return PathResult::Failed {
1867 is_error_from_last_segment: false,
1871 if name == kw::SelfLower {
1872 let mut ctxt = ident.span.ctxt().modern();
1873 module = Some(ModuleOrUniformRoot::Module(
1874 self.resolve_self(&mut ctxt, parent_scope.module)));
1877 if name == kw::PathRoot && ident.span.rust_2018() {
1878 module = Some(ModuleOrUniformRoot::ExternPrelude);
1881 if name == kw::PathRoot &&
1882 ident.span.rust_2015() && self.session.rust_2018() {
1883 // `::a::b` from 2015 macro on 2018 global edition
1884 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
1887 if name == kw::PathRoot ||
1888 name == kw::Crate ||
1889 name == kw::DollarCrate {
1890 // `::a::b`, `crate::a::b` or `$crate::a::b`
1891 module = Some(ModuleOrUniformRoot::Module(
1892 self.resolve_crate_root(ident)));
1898 // Report special messages for path segment keywords in wrong positions.
1899 if ident.is_path_segment_keyword() && i != 0 {
1900 let name_str = if name == kw::PathRoot {
1901 "crate root".to_string()
1903 format!("`{}`", name)
1905 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
1906 format!("global paths cannot start with {}", name_str)
1908 format!("{} in paths can only be used in start position", name_str)
1910 return PathResult::Failed {
1914 is_error_from_last_segment: false,
1918 let binding = if let Some(module) = module {
1919 self.resolve_ident_in_module(
1920 module, ident, ns, parent_scope, record_used, path_span
1922 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
1923 let scopes = ScopeSet::All(ns, opt_ns.is_none());
1924 self.early_resolve_ident_in_lexical_scope(ident, scopes, parent_scope, record_used,
1925 record_used, path_span)
1927 let record_used_id =
1928 if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };
1929 match self.resolve_ident_in_lexical_scope(
1930 ident, ns, parent_scope, record_used_id, path_span, &ribs.unwrap()[ns]
1932 // we found a locally-imported or available item/module
1933 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
1934 // we found a local variable or type param
1935 Some(LexicalScopeBinding::Res(res))
1936 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
1937 record_segment_res(self, res);
1938 return PathResult::NonModule(PartialRes::with_unresolved_segments(
1942 _ => Err(Determinacy::determined(record_used)),
1949 second_binding = Some(binding);
1951 let res = binding.res();
1952 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
1953 if let Some(next_module) = binding.module() {
1954 module = Some(ModuleOrUniformRoot::Module(next_module));
1955 record_segment_res(self, res);
1956 } else if res == Res::ToolMod && i + 1 != path.len() {
1957 if binding.is_import() {
1958 self.session.struct_span_err(
1959 ident.span, "cannot use a tool module through an import"
1961 binding.span, "the tool module imported here"
1964 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
1965 return PathResult::NonModule(PartialRes::new(res));
1966 } else if res == Res::Err {
1967 return PathResult::NonModule(PartialRes::new(Res::Err));
1968 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
1969 self.lint_if_path_starts_with_module(
1975 return PathResult::NonModule(PartialRes::with_unresolved_segments(
1976 res, path.len() - i - 1
1979 let label = format!(
1980 "`{}` is {} {}, not a module",
1986 return PathResult::Failed {
1990 is_error_from_last_segment: is_last,
1994 Err(Undetermined) => return PathResult::Indeterminate,
1995 Err(Determined) => {
1996 if let Some(ModuleOrUniformRoot::Module(module)) = module {
1997 if opt_ns.is_some() && !module.is_normal() {
1998 return PathResult::NonModule(PartialRes::with_unresolved_segments(
1999 module.res().unwrap(), path.len() - i
2003 let module_res = match module {
2004 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2007 let (label, suggestion) = if module_res == self.graph_root.res() {
2008 let is_mod = |res| {
2009 match res { Res::Def(DefKind::Mod, _) => true, _ => false }
2011 let mut candidates =
2012 self.lookup_import_candidates(ident, TypeNS, is_mod);
2013 candidates.sort_by_cached_key(|c| {
2014 (c.path.segments.len(), c.path.to_string())
2016 if let Some(candidate) = candidates.get(0) {
2018 String::from("unresolved import"),
2020 vec![(ident.span, candidate.path.to_string())],
2021 String::from("a similar path exists"),
2022 Applicability::MaybeIncorrect,
2025 } else if !ident.is_reserved() {
2026 (format!("maybe a missing crate `{}`?", ident), None)
2028 // the parser will already have complained about the keyword being used
2029 return PathResult::NonModule(PartialRes::new(Res::Err));
2032 (format!("use of undeclared type or module `{}`", ident), None)
2034 (format!("could not find `{}` in `{}`", ident, path[i - 1].ident), None)
2036 return PathResult::Failed {
2040 is_error_from_last_segment: is_last,
2046 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2048 PathResult::Module(match module {
2049 Some(module) => module,
2050 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2051 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2055 fn lint_if_path_starts_with_module(
2057 crate_lint: CrateLint,
2060 second_binding: Option<&NameBinding<'_>>,
2062 let (diag_id, diag_span) = match crate_lint {
2063 CrateLint::No => return,
2064 CrateLint::SimplePath(id) => (id, path_span),
2065 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2066 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2069 let first_name = match path.get(0) {
2070 // In the 2018 edition this lint is a hard error, so nothing to do
2071 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2075 // We're only interested in `use` paths which should start with
2076 // `{{root}}` currently.
2077 if first_name != kw::PathRoot {
2082 // If this import looks like `crate::...` it's already good
2083 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2084 // Otherwise go below to see if it's an extern crate
2086 // If the path has length one (and it's `PathRoot` most likely)
2087 // then we don't know whether we're gonna be importing a crate or an
2088 // item in our crate. Defer this lint to elsewhere
2092 // If the first element of our path was actually resolved to an
2093 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2094 // warning, this looks all good!
2095 if let Some(binding) = second_binding {
2096 if let NameBindingKind::Import { directive: d, .. } = binding.kind {
2097 // Careful: we still want to rewrite paths from
2098 // renamed extern crates.
2099 if let ImportDirectiveSubclass::ExternCrate { source: None, .. } = d.subclass {
2105 let diag = lint::builtin::BuiltinLintDiagnostics
2106 ::AbsPathWithModule(diag_span);
2107 self.session.buffer_lint_with_diagnostic(
2108 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2110 "absolute paths must start with `self`, `super`, \
2111 `crate`, or an external crate name in the 2018 edition",
2115 // Validate a local resolution (from ribs).
2116 fn validate_res_from_ribs(
2123 all_ribs: &[Rib<'a>],
2125 debug!("validate_res_from_ribs({:?})", res);
2126 let ribs = &all_ribs[rib_index + 1..];
2128 // An invalid forward use of a type parameter from a previous default.
2129 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2131 let res_error = if rib_ident.name == kw::SelfUpper {
2132 ResolutionError::SelfInTyParamDefault
2134 ResolutionError::ForwardDeclaredTyParam
2136 self.report_error(span, res_error);
2138 assert_eq!(res, Res::Err);
2142 // An invalid use of a type parameter as the type of a const parameter.
2143 if let TyParamAsConstParamTy = all_ribs[rib_index].kind {
2145 self.report_error(span, ResolutionError::ConstParamDependentOnTypeParam);
2147 assert_eq!(res, Res::Err);
2153 use ResolutionError::*;
2154 let mut res_err = None;
2158 NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2159 ForwardTyParamBanRibKind | TyParamAsConstParamTy => {
2160 // Nothing to do. Continue.
2162 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2163 // This was an attempt to access an upvar inside a
2164 // named function item. This is not allowed, so we
2167 // We don't immediately trigger a resolve error, because
2168 // we want certain other resolution errors (namely those
2169 // emitted for `ConstantItemRibKind` below) to take
2171 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2174 ConstantItemRibKind => {
2175 // Still doesn't deal with upvars
2177 self.report_error(span, AttemptToUseNonConstantValueInConstant);
2183 if let Some(res_err) = res_err {
2184 self.report_error(span, res_err);
2188 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2190 let has_generic_params = match rib.kind {
2191 NormalRibKind | AssocItemRibKind |
2192 ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2193 ConstantItemRibKind | TyParamAsConstParamTy => {
2194 // Nothing to do. Continue.
2197 // This was an attempt to use a type parameter outside its scope.
2198 ItemRibKind(has_generic_params) => has_generic_params,
2199 FnItemRibKind => HasGenericParams::Yes,
2203 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2204 res, has_generic_params));
2209 Res::Def(DefKind::ConstParam, _) => {
2210 let mut ribs = ribs.iter().peekable();
2211 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2212 // When declaring const parameters inside function signatures, the first rib
2213 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2214 // (spuriously) conflicting with the const param.
2218 let has_generic_params = match rib.kind {
2219 ItemRibKind(has_generic_params) => has_generic_params,
2220 FnItemRibKind => HasGenericParams::Yes,
2224 // This was an attempt to use a const parameter outside its scope.
2226 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2227 res, has_generic_params));
2237 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2238 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2239 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2240 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2244 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2245 vis.is_accessible_from(module.normal_ancestor_id, self)
2248 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2249 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2250 if !ptr::eq(module, old_module) {
2251 span_bug!(binding.span, "parent module is reset for binding");
2256 fn disambiguate_legacy_vs_modern(
2258 legacy: &'a NameBinding<'a>,
2259 modern: &'a NameBinding<'a>,
2261 // Some non-controversial subset of ambiguities "modern macro name" vs "macro_rules"
2262 // is disambiguated to mitigate regressions from macro modularization.
2263 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2264 match (self.binding_parent_modules.get(&PtrKey(legacy)),
2265 self.binding_parent_modules.get(&PtrKey(modern))) {
2266 (Some(legacy), Some(modern)) =>
2267 legacy.normal_ancestor_id == modern.normal_ancestor_id &&
2268 modern.is_ancestor_of(legacy),
2273 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
2275 if b.span.is_dummy() {
2276 let add_built_in = match b.res() {
2277 // These already contain the "built-in" prefix or look bad with it.
2278 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
2281 let (built_in, from) = if from_prelude {
2282 ("", " from prelude")
2283 } else if b.is_extern_crate() && !b.is_import() &&
2284 self.session.opts.externs.get(&ident.as_str()).is_some() {
2285 ("", " passed with `--extern`")
2286 } else if add_built_in {
2292 let article = if built_in.is_empty() { res.article() } else { "a" };
2293 format!("{a}{built_in} {thing}{from}",
2294 a = article, thing = res.descr(), built_in = built_in, from = from)
2296 let introduced = if b.is_import() { "imported" } else { "defined" };
2297 format!("the {thing} {introduced} here",
2298 thing = res.descr(), introduced = introduced)
2302 fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
2303 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
2304 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
2305 // We have to print the span-less alternative first, otherwise formatting looks bad.
2306 (b2, b1, misc2, misc1, true)
2308 (b1, b2, misc1, misc2, false)
2311 let mut err = struct_span_err!(self.session, ident.span, E0659,
2312 "`{ident}` is ambiguous ({why})",
2313 ident = ident, why = kind.descr());
2314 err.span_label(ident.span, "ambiguous name");
2316 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
2317 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
2318 let note_msg = format!("`{ident}` could{also} refer to {what}",
2319 ident = ident, also = also, what = what);
2321 let thing = b.res().descr();
2322 let mut help_msgs = Vec::new();
2323 if b.is_glob_import() && (kind == AmbiguityKind::GlobVsGlob ||
2324 kind == AmbiguityKind::GlobVsExpanded ||
2325 kind == AmbiguityKind::GlobVsOuter &&
2326 swapped != also.is_empty()) {
2327 help_msgs.push(format!("consider adding an explicit import of \
2328 `{ident}` to disambiguate", ident = ident))
2330 if b.is_extern_crate() && ident.span.rust_2018() {
2331 help_msgs.push(format!(
2332 "use `::{ident}` to refer to this {thing} unambiguously",
2333 ident = ident, thing = thing,
2336 if misc == AmbiguityErrorMisc::SuggestCrate {
2337 help_msgs.push(format!(
2338 "use `crate::{ident}` to refer to this {thing} unambiguously",
2339 ident = ident, thing = thing,
2341 } else if misc == AmbiguityErrorMisc::SuggestSelf {
2342 help_msgs.push(format!(
2343 "use `self::{ident}` to refer to this {thing} unambiguously",
2344 ident = ident, thing = thing,
2348 err.span_note(b.span, ¬e_msg);
2349 for (i, help_msg) in help_msgs.iter().enumerate() {
2350 let or = if i == 0 { "" } else { "or " };
2351 err.help(&format!("{}{}", or, help_msg));
2355 could_refer_to(b1, misc1, "");
2356 could_refer_to(b2, misc2, " also");
2360 fn report_errors(&mut self, krate: &Crate) {
2361 self.report_with_use_injections(krate);
2363 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2364 let msg = "macro-expanded `macro_export` macros from the current crate \
2365 cannot be referred to by absolute paths";
2366 self.session.buffer_lint_with_diagnostic(
2367 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2368 CRATE_NODE_ID, span_use, msg,
2369 lint::builtin::BuiltinLintDiagnostics::
2370 MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2374 for ambiguity_error in &self.ambiguity_errors {
2375 self.report_ambiguity_error(ambiguity_error);
2378 let mut reported_spans = FxHashSet::default();
2379 for &PrivacyError(dedup_span, ident, binding) in &self.privacy_errors {
2380 if reported_spans.insert(dedup_span) {
2381 let mut err = struct_span_err!(
2385 "{} `{}` is private",
2386 binding.res().descr(),
2389 if let NameBindingKind::Res(
2390 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _
2392 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
2393 if let Some(fields) = self.field_names.get(&def_id) {
2394 let first_field = fields.first().expect("empty field list in the map");
2396 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
2397 "a tuple struct constructor is private if any of its fields is private",
2406 fn report_with_use_injections(&mut self, krate: &Crate) {
2407 for UseError { mut err, candidates, node_id, better } in self.use_injections.drain(..) {
2408 let (span, found_use) = UsePlacementFinder::check(krate, node_id);
2409 if !candidates.is_empty() {
2410 diagnostics::show_candidates(&mut err, span, &candidates, better, found_use);
2416 fn report_conflict<'b>(&mut self,
2420 new_binding: &NameBinding<'b>,
2421 old_binding: &NameBinding<'b>) {
2422 // Error on the second of two conflicting names
2423 if old_binding.span.lo() > new_binding.span.lo() {
2424 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2427 let container = match parent.kind {
2428 ModuleKind::Def(DefKind::Mod, _, _) => "module",
2429 ModuleKind::Def(DefKind::Trait, _, _) => "trait",
2430 ModuleKind::Block(..) => "block",
2434 let old_noun = match old_binding.is_import() {
2436 false => "definition",
2439 let new_participle = match new_binding.is_import() {
2444 let (name, span) = (ident.name, self.session.source_map().def_span(new_binding.span));
2446 if let Some(s) = self.name_already_seen.get(&name) {
2452 let old_kind = match (ns, old_binding.module()) {
2453 (ValueNS, _) => "value",
2454 (MacroNS, _) => "macro",
2455 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2456 (TypeNS, Some(module)) if module.is_normal() => "module",
2457 (TypeNS, Some(module)) if module.is_trait() => "trait",
2458 (TypeNS, _) => "type",
2461 let msg = format!("the name `{}` is defined multiple times", name);
2463 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2464 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2465 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2466 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2467 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2469 _ => match (old_binding.is_import(), new_binding.is_import()) {
2470 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2471 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2472 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2476 err.note(&format!("`{}` must be defined only once in the {} namespace of this {}",
2481 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2483 self.session.source_map().def_span(old_binding.span),
2484 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2487 // See https://github.com/rust-lang/rust/issues/32354
2488 use NameBindingKind::Import;
2489 let directive = match (&new_binding.kind, &old_binding.kind) {
2490 // If there are two imports where one or both have attributes then prefer removing the
2491 // import without attributes.
2492 (Import { directive: new, .. }, Import { directive: old, .. }) if {
2493 !new_binding.span.is_dummy() && !old_binding.span.is_dummy() &&
2494 (new.has_attributes || old.has_attributes)
2496 if old.has_attributes {
2497 Some((new, new_binding.span, true))
2499 Some((old, old_binding.span, true))
2502 // Otherwise prioritize the new binding.
2503 (Import { directive, .. }, other) if !new_binding.span.is_dummy() =>
2504 Some((directive, new_binding.span, other.is_import())),
2505 (other, Import { directive, .. }) if !old_binding.span.is_dummy() =>
2506 Some((directive, old_binding.span, other.is_import())),
2510 // Check if the target of the use for both bindings is the same.
2511 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2512 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2513 let from_item = self.extern_prelude.get(&ident)
2514 .map(|entry| entry.introduced_by_item)
2516 // Only suggest removing an import if both bindings are to the same def, if both spans
2517 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2518 // been introduced by a item.
2519 let should_remove_import = duplicate && !has_dummy_span &&
2520 ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2523 Some((directive, span, true)) if should_remove_import && directive.is_nested() =>
2524 self.add_suggestion_for_duplicate_nested_use(&mut err, directive, span),
2525 Some((directive, _, true)) if should_remove_import && !directive.is_glob() => {
2526 // Simple case - remove the entire import. Due to the above match arm, this can
2527 // only be a single use so just remove it entirely.
2528 err.tool_only_span_suggestion(
2529 directive.use_span_with_attributes,
2530 "remove unnecessary import",
2532 Applicability::MaybeIncorrect,
2535 Some((directive, span, _)) =>
2536 self.add_suggestion_for_rename_of_use(&mut err, name, directive, span),
2541 self.name_already_seen.insert(name, span);
2544 /// This function adds a suggestion to change the binding name of a new import that conflicts
2545 /// with an existing import.
2547 /// ```ignore (diagnostic)
2548 /// help: you can use `as` to change the binding name of the import
2550 /// LL | use foo::bar as other_bar;
2551 /// | ^^^^^^^^^^^^^^^^^^^^^
2553 fn add_suggestion_for_rename_of_use(
2555 err: &mut DiagnosticBuilder<'_>,
2557 directive: &ImportDirective<'_>,
2560 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
2561 format!("Other{}", name)
2563 format!("other_{}", name)
2566 let mut suggestion = None;
2567 match directive.subclass {
2568 ImportDirectiveSubclass::SingleImport { type_ns_only: true, .. } =>
2569 suggestion = Some(format!("self as {}", suggested_name)),
2570 ImportDirectiveSubclass::SingleImport { source, .. } => {
2571 if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0)
2572 .map(|pos| pos as usize) {
2573 if let Ok(snippet) = self.session.source_map()
2574 .span_to_snippet(binding_span) {
2575 if pos <= snippet.len() {
2576 suggestion = Some(format!(
2580 if snippet.ends_with(";") { ";" } else { "" }
2586 ImportDirectiveSubclass::ExternCrate { source, target, .. } =>
2587 suggestion = Some(format!(
2588 "extern crate {} as {};",
2589 source.unwrap_or(target.name),
2592 _ => unreachable!(),
2595 let rename_msg = "you can use `as` to change the binding name of the import";
2596 if let Some(suggestion) = suggestion {
2597 err.span_suggestion(
2601 Applicability::MaybeIncorrect,
2604 err.span_label(binding_span, rename_msg);
2608 /// This function adds a suggestion to remove a unnecessary binding from an import that is
2609 /// nested. In the following example, this function will be invoked to remove the `a` binding
2610 /// in the second use statement:
2612 /// ```ignore (diagnostic)
2613 /// use issue_52891::a;
2614 /// use issue_52891::{d, a, e};
2617 /// The following suggestion will be added:
2619 /// ```ignore (diagnostic)
2620 /// use issue_52891::{d, a, e};
2621 /// ^-- help: remove unnecessary import
2624 /// If the nested use contains only one import then the suggestion will remove the entire
2627 /// It is expected that the directive provided is a nested import - this isn't checked by the
2628 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
2629 /// as characters expected by span manipulations won't be present.
2630 fn add_suggestion_for_duplicate_nested_use(
2632 err: &mut DiagnosticBuilder<'_>,
2633 directive: &ImportDirective<'_>,
2636 assert!(directive.is_nested());
2637 let message = "remove unnecessary import";
2639 // Two examples will be used to illustrate the span manipulations we're doing:
2641 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
2642 // `a` and `directive.use_span` is `issue_52891::{d, a, e};`.
2643 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
2644 // `a` and `directive.use_span` is `issue_52891::{d, e, a};`.
2646 let (found_closing_brace, span) = find_span_of_binding_until_next_binding(
2647 self.session, binding_span, directive.use_span,
2650 // If there was a closing brace then identify the span to remove any trailing commas from
2651 // previous imports.
2652 if found_closing_brace {
2653 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
2654 err.tool_only_span_suggestion(span, message, String::new(),
2655 Applicability::MaybeIncorrect);
2657 // Remove the entire line if we cannot extend the span back, this indicates a
2658 // `issue_52891::{self}` case.
2659 err.span_suggestion(directive.use_span_with_attributes, message, String::new(),
2660 Applicability::MaybeIncorrect);
2666 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
2669 fn extern_prelude_get(&mut self, ident: Ident, speculative: bool)
2670 -> Option<&'a NameBinding<'a>> {
2671 if ident.is_path_segment_keyword() {
2672 // Make sure `self`, `super` etc produce an error when passed to here.
2675 self.extern_prelude.get(&ident.modern()).cloned().and_then(|entry| {
2676 if let Some(binding) = entry.extern_crate_item {
2677 if !speculative && entry.introduced_by_item {
2678 self.record_use(ident, TypeNS, binding, false);
2682 let crate_id = if !speculative {
2683 self.crate_loader.process_path_extern(ident.name, ident.span)
2684 } else if let Some(crate_id) =
2685 self.crate_loader.maybe_process_path_extern(ident.name, ident.span) {
2690 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
2691 Some((crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
2692 .to_name_binding(self.arenas))
2697 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
2698 /// isn't something that can be returned because it can't be made to live that long,
2699 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
2700 /// just that an error occurred.
2701 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
2702 pub fn resolve_str_path_error(
2703 &mut self, span: Span, path_str: &str, ns: Namespace, module_id: NodeId
2704 ) -> Result<(ast::Path, Res), ()> {
2705 let path = if path_str.starts_with("::") {
2708 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
2710 path_str.split("::").skip(1).map(Ident::from_str)
2712 .map(|i| self.new_ast_path_segment(i))
2720 .map(Ident::from_str)
2721 .map(|i| self.new_ast_path_segment(i))
2725 let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| {
2726 let def_id = self.definitions.local_def_id(module_id);
2727 self.module_map.get(&def_id).copied().unwrap_or(self.graph_root)
2729 let parent_scope = &ParentScope::module(module);
2730 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
2734 // Resolve a path passed from rustdoc or HIR lowering.
2735 fn resolve_ast_path(
2739 parent_scope: &ParentScope<'a>,
2740 ) -> Result<Res, (Span, ResolutionError<'a>)> {
2741 match self.resolve_path(
2742 &Segment::from_path(path), Some(ns), parent_scope, true, path.span, CrateLint::No
2744 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
2745 Ok(module.res().unwrap()),
2746 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
2747 Ok(path_res.base_res()),
2748 PathResult::NonModule(..) => {
2749 Err((path.span, ResolutionError::FailedToResolve {
2750 label: String::from("type-relative paths are not supported in this context"),
2754 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
2755 PathResult::Failed { span, label, suggestion, .. } => {
2756 Err((span, ResolutionError::FailedToResolve {
2764 fn new_ast_path_segment(&self, ident: Ident) -> ast::PathSegment {
2765 let mut seg = ast::PathSegment::from_ident(ident);
2766 seg.id = self.session.next_node_id();
2771 fn names_to_string(names: &[Name]) -> String {
2772 let mut result = String::new();
2773 for (i, name) in names.iter()
2774 .filter(|name| **name != kw::PathRoot)
2777 result.push_str("::");
2779 result.push_str(&name.as_str());
2784 fn path_names_to_string(path: &Path) -> String {
2785 names_to_string(&path.segments.iter()
2786 .map(|seg| seg.ident.name)
2787 .collect::<Vec<_>>())
2790 /// A somewhat inefficient routine to obtain the name of a module.
2791 fn module_to_string(module: Module<'_>) -> Option<String> {
2792 let mut names = Vec::new();
2794 fn collect_mod(names: &mut Vec<Name>, module: Module<'_>) {
2795 if let ModuleKind::Def(.., name) = module.kind {
2796 if let Some(parent) = module.parent {
2798 collect_mod(names, parent);
2801 names.push(Name::intern("<opaque>"));
2802 collect_mod(names, module.parent.unwrap());
2805 collect_mod(&mut names, module);
2807 if names.is_empty() {
2811 Some(names_to_string(&names))
2814 #[derive(Copy, Clone, Debug)]
2816 /// Do not issue the lint.
2819 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
2820 /// In this case, we can take the span of that path.
2823 /// This lint comes from a `use` statement. In this case, what we
2824 /// care about really is the *root* `use` statement; e.g., if we
2825 /// have nested things like `use a::{b, c}`, we care about the
2827 UsePath { root_id: NodeId, root_span: Span },
2829 /// This is the "trait item" from a fully qualified path. For example,
2830 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
2831 /// The `path_span` is the span of the to the trait itself (`X::Y`).
2832 QPathTrait { qpath_id: NodeId, qpath_span: Span },
2836 fn node_id(&self) -> Option<NodeId> {
2838 CrateLint::No => None,
2839 CrateLint::SimplePath(id) |
2840 CrateLint::UsePath { root_id: id, .. } |
2841 CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),