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, MetadataLoaderDyn};
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, CrateNum, DefId};
30 use rustc::hir::{TraitMap, GlobMap};
31 use rustc::ty::{self, DefIdTree, ResolverOutputs};
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::{struct_span_err, unwrap_or};
39 use syntax::ast::{self, Name, NodeId, Ident, FloatTy, IntTy, UintTy};
40 use syntax::ast::{CRATE_NODE_ID, Crate};
41 use syntax::ast::{ItemKind, Path};
43 use syntax::print::pprust;
44 use syntax::symbol::{kw, sym};
45 use syntax::source_map::Spanned;
46 use syntax::visit::{self, Visitor};
47 use syntax_expand::base::SyntaxExtension;
48 use syntax_pos::hygiene::{MacroKind, ExpnId, Transparency, SyntaxContext};
49 use syntax_pos::{Span, DUMMY_SP};
50 use errors::{Applicability, DiagnosticBuilder};
54 use std::cell::{Cell, RefCell};
55 use std::{cmp, fmt, iter, ptr};
56 use std::collections::BTreeSet;
57 use rustc_data_structures::ptr_key::PtrKey;
58 use rustc_data_structures::sync::Lrc;
59 use rustc_data_structures::fx::FxIndexMap;
61 use diagnostics::{Suggestion, ImportSuggestion};
62 use diagnostics::{find_span_of_binding_until_next_binding, extend_span_to_previous_binding};
63 use late::{HasGenericParams, PathSource, Rib, RibKind::*};
64 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
65 use macros::{LegacyBinding, LegacyScope};
67 type Res = def::Res<NodeId>;
74 mod build_reduced_graph;
82 #[derive(Copy, Clone, PartialEq, Debug)]
83 pub enum Determinacy {
89 fn determined(determined: bool) -> Determinacy {
90 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
94 /// A specific scope in which a name can be looked up.
95 /// This enum is currently used only for early resolution (imports and macros),
96 /// but not for late resolution yet.
97 #[derive(Clone, Copy)]
100 MacroRules(LegacyScope<'a>),
113 /// Names from different contexts may want to visit different subsets of all specific scopes
114 /// with different restrictions when looking up the resolution.
115 /// This enum is currently used only for early resolution (imports and macros),
116 /// but not for late resolution yet.
118 /// All scopes with the given namespace.
119 All(Namespace, /*is_import*/ bool),
120 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
121 AbsolutePath(Namespace),
122 /// All scopes with macro namespace and the given macro kind restriction.
126 /// Everything you need to know about a name's location to resolve it.
127 /// Serves as a starting point for the scope visitor.
128 /// This struct is currently used only for early resolution (imports and macros),
129 /// but not for late resolution yet.
130 #[derive(Clone, Copy, Debug)]
131 pub struct ParentScope<'a> {
134 legacy: LegacyScope<'a>,
135 derives: &'a [ast::Path],
138 impl<'a> ParentScope<'a> {
139 /// Creates a parent scope with the passed argument used as the module scope component,
140 /// and other scope components set to default empty values.
141 pub fn module(module: Module<'a>) -> ParentScope<'a> {
144 expansion: ExpnId::root(),
145 legacy: LegacyScope::Empty,
152 struct BindingError {
154 origin: BTreeSet<Span>,
155 target: BTreeSet<Span>,
159 impl PartialOrd for BindingError {
160 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
161 Some(self.cmp(other))
165 impl PartialEq for BindingError {
166 fn eq(&self, other: &BindingError) -> bool {
167 self.name == other.name
171 impl Ord for BindingError {
172 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
173 self.name.cmp(&other.name)
177 enum ResolutionError<'a> {
178 /// Error E0401: can't use type or const parameters from outer function.
179 GenericParamsFromOuterFunction(Res, HasGenericParams),
180 /// Error E0403: the name is already used for a type or const parameter in this generic
182 NameAlreadyUsedInParameterList(Name, Span),
183 /// Error E0407: method is not a member of trait.
184 MethodNotMemberOfTrait(Name, &'a str),
185 /// Error E0437: type is not a member of trait.
186 TypeNotMemberOfTrait(Name, &'a str),
187 /// Error E0438: const is not a member of trait.
188 ConstNotMemberOfTrait(Name, &'a str),
189 /// Error E0408: variable `{}` is not bound in all patterns.
190 VariableNotBoundInPattern(&'a BindingError),
191 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
192 VariableBoundWithDifferentMode(Name, Span),
193 /// Error E0415: identifier is bound more than once in this parameter list.
194 IdentifierBoundMoreThanOnceInParameterList(&'a str),
195 /// Error E0416: identifier is bound more than once in the same pattern.
196 IdentifierBoundMoreThanOnceInSamePattern(&'a str),
197 /// Error E0426: use of undeclared label.
198 UndeclaredLabel(&'a str, Option<Name>),
199 /// Error E0429: `self` imports are only allowed within a `{ }` list.
200 SelfImportsOnlyAllowedWithin,
201 /// Error E0430: `self` import can only appear once in the list.
202 SelfImportCanOnlyAppearOnceInTheList,
203 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
204 SelfImportOnlyInImportListWithNonEmptyPrefix,
205 /// Error E0433: failed to resolve.
206 FailedToResolve { label: String, suggestion: Option<Suggestion> },
207 /// Error E0434: can't capture dynamic environment in a fn item.
208 CannotCaptureDynamicEnvironmentInFnItem,
209 /// Error E0435: attempt to use a non-constant value in a constant.
210 AttemptToUseNonConstantValueInConstant,
211 /// Error E0530: `X` bindings cannot shadow `Y`s.
212 BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
213 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
214 ForwardDeclaredTyParam, // FIXME(const_generics:defaults)
215 /// Error E0735: type parameters with a default cannot use `Self`
216 SelfInTyParamDefault,
219 // A minimal representation of a path segment. We use this in resolve because
220 // we synthesize 'path segments' which don't have the rest of an AST or HIR
222 #[derive(Clone, Copy, Debug)]
229 fn from_path(path: &Path) -> Vec<Segment> {
230 path.segments.iter().map(|s| s.into()).collect()
233 fn from_ident(ident: Ident) -> Segment {
240 fn names_to_string(segments: &[Segment]) -> String {
241 names_to_string(&segments.iter()
242 .map(|seg| seg.ident.name)
243 .collect::<Vec<_>>())
247 impl<'a> From<&'a ast::PathSegment> for Segment {
248 fn from(seg: &'a ast::PathSegment) -> Segment {
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 {
269 visit::walk_crate(&mut finder, krate);
270 (finder.span, finder.found_use)
274 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
277 module: &'tcx ast::Mod,
279 _: &[ast::Attribute],
282 if self.span.is_some() {
285 if node_id != self.target_module {
286 visit::walk_mod(self, module);
289 // find a use statement
290 for item in &module.items {
292 ItemKind::Use(..) => {
293 // don't suggest placing a use before the prelude
294 // import or other generated ones
295 if !item.span.from_expansion() {
296 self.span = Some(item.span.shrink_to_lo());
297 self.found_use = true;
301 // don't place use before extern crate
302 ItemKind::ExternCrate(_) => {}
303 // but place them before the first other item
304 _ => if self.span.map_or(true, |span| item.span < span ) {
305 if !item.span.from_expansion() {
306 // don't insert between attributes and an item
307 if item.attrs.is_empty() {
308 self.span = Some(item.span.shrink_to_lo());
310 // find the first attribute on the item
311 for attr in &item.attrs {
312 if self.span.map_or(true, |span| attr.span < span) {
313 self.span = Some(attr.span.shrink_to_lo());
324 /// An intermediate resolution result.
326 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
327 /// items are visible in their whole block, while `Res`es only from the place they are defined
330 enum LexicalScopeBinding<'a> {
331 Item(&'a NameBinding<'a>),
335 impl<'a> LexicalScopeBinding<'a> {
336 fn item(self) -> Option<&'a NameBinding<'a>> {
338 LexicalScopeBinding::Item(binding) => Some(binding),
343 fn res(self) -> Res {
345 LexicalScopeBinding::Item(binding) => binding.res(),
346 LexicalScopeBinding::Res(res) => res,
351 #[derive(Copy, Clone, Debug)]
352 enum ModuleOrUniformRoot<'a> {
356 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
357 CrateRootAndExternPrelude,
359 /// Virtual module that denotes resolution in extern prelude.
360 /// Used for paths starting with `::` on 2018 edition.
363 /// Virtual module that denotes resolution in current scope.
364 /// Used only for resolving single-segment imports. The reason it exists is that import paths
365 /// are always split into two parts, the first of which should be some kind of module.
369 impl ModuleOrUniformRoot<'_> {
370 fn same_def(lhs: Self, rhs: Self) -> bool {
372 (ModuleOrUniformRoot::Module(lhs),
373 ModuleOrUniformRoot::Module(rhs)) => lhs.def_id() == rhs.def_id(),
374 (ModuleOrUniformRoot::CrateRootAndExternPrelude,
375 ModuleOrUniformRoot::CrateRootAndExternPrelude) |
376 (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) |
377 (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
383 #[derive(Clone, Debug)]
384 enum PathResult<'a> {
385 Module(ModuleOrUniformRoot<'a>),
386 NonModule(PartialRes),
391 suggestion: Option<Suggestion>,
392 is_error_from_last_segment: bool,
397 /// An anonymous module; e.g., just a block.
402 /// { // This is an anonymous module
403 /// f(); // This resolves to (2) as we are inside the block.
406 /// f(); // Resolves to (1)
410 /// Any module with a name.
414 /// * A normal module ‒ either `mod from_file;` or `mod from_block { }`.
415 /// * A trait or an enum (it implicitly contains associated types, methods and variant
417 Def(DefKind, DefId, Name),
421 /// Get name of the module.
422 pub fn name(&self) -> Option<Name> {
424 ModuleKind::Block(..) => None,
425 ModuleKind::Def(.., name) => Some(*name),
430 /// A key that identifies a binding in a given `Module`.
432 /// Multiple bindings in the same module can have the same key (in a valid
433 /// program) if all but one of them come from glob imports.
434 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
436 /// The identifier for the binding, aways the `modern` version of the
440 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
441 /// `_` in the expanded AST that introduced this binding.
445 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
447 /// One node in the tree of modules.
448 pub struct ModuleData<'a> {
449 parent: Option<Module<'a>>,
452 // The def id of the closest normal module (`mod`) ancestor (including this module).
453 normal_ancestor_id: DefId,
455 // Mapping between names and their (possibly in-progress) resolutions in this module.
456 // Resolutions in modules from other crates are not populated until accessed.
457 lazy_resolutions: Resolutions<'a>,
458 // True if this is a module from other crate that needs to be populated on access.
459 populate_on_access: Cell<bool>,
461 // Macro invocations that can expand into items in this module.
462 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
464 no_implicit_prelude: bool,
466 glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
467 globs: RefCell<Vec<&'a ImportDirective<'a>>>,
469 // Used to memoize the traits in this module for faster searches through all traits in scope.
470 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
472 /// Span of the module itself. Used for error reporting.
478 type Module<'a> = &'a ModuleData<'a>;
480 impl<'a> ModuleData<'a> {
481 fn new(parent: Option<Module<'a>>,
483 normal_ancestor_id: DefId,
485 span: Span) -> Self {
490 lazy_resolutions: Default::default(),
491 populate_on_access: Cell::new(!normal_ancestor_id.is_local()),
492 unexpanded_invocations: Default::default(),
493 no_implicit_prelude: false,
494 glob_importers: RefCell::new(Vec::new()),
495 globs: RefCell::new(Vec::new()),
496 traits: RefCell::new(None),
502 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
503 where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
505 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
506 name_resolution.borrow().binding.map(|binding| 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, ..) | ModuleKind::Def(DefKind::Trait, ..) =>
542 self.parent.expect("enum or trait module without a parent"),
547 fn is_ancestor_of(&self, mut other: &Self) -> bool {
548 while !ptr::eq(self, other) {
549 if let Some(parent) = other.parent {
559 impl<'a> fmt::Debug for ModuleData<'a> {
560 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
561 write!(f, "{:?}", self.res())
565 /// Records a possibly-private value, type, or module definition.
566 #[derive(Clone, Debug)]
567 pub struct NameBinding<'a> {
568 kind: NameBindingKind<'a>,
569 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
575 pub trait ToNameBinding<'a> {
576 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
579 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
580 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
585 #[derive(Clone, Debug)]
586 enum NameBindingKind<'a> {
587 Res(Res, /* is_macro_export */ bool),
590 binding: &'a NameBinding<'a>,
591 directive: &'a ImportDirective<'a>,
596 impl<'a> NameBindingKind<'a> {
597 /// Is this a name binding of a import?
598 fn is_import(&self) -> bool {
600 NameBindingKind::Import { .. } => true,
606 struct PrivacyError<'a>(Span, Ident, &'a NameBinding<'a>);
608 struct UseError<'a> {
609 err: DiagnosticBuilder<'a>,
610 /// Attach `use` statements for these candidates.
611 candidates: Vec<ImportSuggestion>,
612 /// The `NodeId` of the module to place the use-statements in.
614 /// Whether the diagnostic should state that it's "better".
618 #[derive(Clone, Copy, PartialEq, Debug)]
631 fn descr(self) -> &'static str {
633 AmbiguityKind::Import =>
634 "name vs any other name during import resolution",
635 AmbiguityKind::BuiltinAttr =>
636 "built-in attribute vs any other name",
637 AmbiguityKind::DeriveHelper =>
638 "derive helper attribute vs any other name",
639 AmbiguityKind::LegacyVsModern =>
640 "`macro_rules` vs non-`macro_rules` from other module",
641 AmbiguityKind::GlobVsOuter =>
642 "glob import vs any other name from outer scope during import/macro resolution",
643 AmbiguityKind::GlobVsGlob =>
644 "glob import vs glob import in the same module",
645 AmbiguityKind::GlobVsExpanded =>
646 "glob import vs macro-expanded name in the same \
647 module during import/macro resolution",
648 AmbiguityKind::MoreExpandedVsOuter =>
649 "macro-expanded name vs less macro-expanded name \
650 from outer scope during import/macro resolution",
655 /// Miscellaneous bits of metadata for better ambiguity error reporting.
656 #[derive(Clone, Copy, PartialEq)]
657 enum AmbiguityErrorMisc {
664 struct AmbiguityError<'a> {
667 b1: &'a NameBinding<'a>,
668 b2: &'a NameBinding<'a>,
669 misc1: AmbiguityErrorMisc,
670 misc2: AmbiguityErrorMisc,
673 impl<'a> NameBinding<'a> {
674 fn module(&self) -> Option<Module<'a>> {
676 NameBindingKind::Module(module) => Some(module),
677 NameBindingKind::Import { binding, .. } => binding.module(),
682 fn res(&self) -> Res {
684 NameBindingKind::Res(res, _) => res,
685 NameBindingKind::Module(module) => module.res().unwrap(),
686 NameBindingKind::Import { binding, .. } => binding.res(),
690 fn is_ambiguity(&self) -> bool {
691 self.ambiguity.is_some() || match self.kind {
692 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
697 // We sometimes need to treat variants as `pub` for backwards compatibility.
698 fn pseudo_vis(&self) -> ty::Visibility {
699 if self.is_variant() && self.res().def_id().is_local() {
700 ty::Visibility::Public
706 fn is_variant(&self) -> bool {
708 NameBindingKind::Res(Res::Def(DefKind::Variant, _), _) |
709 NameBindingKind::Res(Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _), _) => true,
714 fn is_extern_crate(&self) -> bool {
716 NameBindingKind::Import {
717 directive: &ImportDirective {
718 subclass: ImportDirectiveSubclass::ExternCrate { .. }, ..
721 NameBindingKind::Module(
722 &ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }
723 ) => def_id.index == CRATE_DEF_INDEX,
728 fn is_import(&self) -> bool {
730 NameBindingKind::Import { .. } => true,
735 fn is_glob_import(&self) -> bool {
737 NameBindingKind::Import { directive, .. } => directive.is_glob(),
742 fn is_importable(&self) -> bool {
744 Res::Def(DefKind::AssocConst, _)
745 | Res::Def(DefKind::Method, _)
746 | Res::Def(DefKind::AssocTy, _) => false,
751 fn is_macro_def(&self) -> bool {
753 NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
758 fn macro_kind(&self) -> Option<MacroKind> {
759 self.res().macro_kind()
762 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
763 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
764 // Then this function returns `true` if `self` may emerge from a macro *after* that
765 // in some later round and screw up our previously found resolution.
766 // See more detailed explanation in
767 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
768 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
769 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
770 // Expansions are partially ordered, so "may appear after" is an inversion of
771 // "certainly appears before or simultaneously" and includes unordered cases.
772 let self_parent_expansion = self.expansion;
773 let other_parent_expansion = binding.expansion;
774 let certainly_before_other_or_simultaneously =
775 other_parent_expansion.is_descendant_of(self_parent_expansion);
776 let certainly_before_invoc_or_simultaneously =
777 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
778 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
782 /// Interns the names of the primitive types.
784 /// All other types are defined somewhere and possibly imported, but the primitive ones need
785 /// special handling, since they have no place of origin.
786 struct PrimitiveTypeTable {
787 primitive_types: FxHashMap<Name, PrimTy>,
790 impl PrimitiveTypeTable {
791 fn new() -> PrimitiveTypeTable {
792 let mut table = FxHashMap::default();
794 table.insert(sym::bool, Bool);
795 table.insert(sym::char, Char);
796 table.insert(sym::f32, Float(FloatTy::F32));
797 table.insert(sym::f64, Float(FloatTy::F64));
798 table.insert(sym::isize, Int(IntTy::Isize));
799 table.insert(sym::i8, Int(IntTy::I8));
800 table.insert(sym::i16, Int(IntTy::I16));
801 table.insert(sym::i32, Int(IntTy::I32));
802 table.insert(sym::i64, Int(IntTy::I64));
803 table.insert(sym::i128, Int(IntTy::I128));
804 table.insert(sym::str, Str);
805 table.insert(sym::usize, Uint(UintTy::Usize));
806 table.insert(sym::u8, Uint(UintTy::U8));
807 table.insert(sym::u16, Uint(UintTy::U16));
808 table.insert(sym::u32, Uint(UintTy::U32));
809 table.insert(sym::u64, Uint(UintTy::U64));
810 table.insert(sym::u128, Uint(UintTy::U128));
811 Self { primitive_types: table }
815 #[derive(Debug, Default, Clone)]
816 pub struct ExternPreludeEntry<'a> {
817 extern_crate_item: Option<&'a NameBinding<'a>>,
818 pub introduced_by_item: bool,
821 /// The main resolver class.
823 /// This is the visitor that walks the whole crate.
824 pub struct Resolver<'a> {
825 session: &'a Session,
827 definitions: Definitions,
829 graph_root: Module<'a>,
831 prelude: Option<Module<'a>>,
832 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
834 /// N.B., this is used only for better diagnostics, not name resolution itself.
835 has_self: FxHashSet<DefId>,
837 /// Names of fields of an item `DefId` accessible with dot syntax.
838 /// Used for hints during error reporting.
839 field_names: FxHashMap<DefId, Vec<Spanned<Name>>>,
841 /// All imports known to succeed or fail.
842 determined_imports: Vec<&'a ImportDirective<'a>>,
844 /// All non-determined imports.
845 indeterminate_imports: Vec<&'a ImportDirective<'a>>,
847 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
848 /// We are resolving a last import segment during import validation.
849 last_import_segment: bool,
850 /// This binding should be ignored during in-module resolution, so that we don't get
851 /// "self-confirming" import resolutions during import validation.
852 blacklisted_binding: Option<&'a NameBinding<'a>>,
854 /// The idents for the primitive types.
855 primitive_type_table: PrimitiveTypeTable,
857 /// Resolutions for nodes that have a single resolution.
858 partial_res_map: NodeMap<PartialRes>,
859 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
860 import_res_map: NodeMap<PerNS<Option<Res>>>,
861 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
862 label_res_map: NodeMap<NodeId>,
864 /// `CrateNum` resolutions of `extern crate` items.
865 extern_crate_map: NodeMap<CrateNum>,
866 export_map: ExportMap<NodeId>,
869 /// A map from nodes to anonymous modules.
870 /// Anonymous modules are pseudo-modules that are implicitly created around items
871 /// contained within blocks.
873 /// For example, if we have this:
881 /// There will be an anonymous module created around `g` with the ID of the
882 /// entry block for `f`.
883 block_map: NodeMap<Module<'a>>,
884 /// A fake module that contains no definition and no prelude. Used so that
885 /// some AST passes can generate identifiers that only resolve to local or
887 empty_module: Module<'a>,
888 module_map: FxHashMap<DefId, Module<'a>>,
889 extern_module_map: FxHashMap<DefId, Module<'a>>,
890 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
891 underscore_disambiguator: u32,
893 /// Maps glob imports to the names of items actually imported.
896 used_imports: FxHashSet<(NodeId, Namespace)>,
897 maybe_unused_trait_imports: NodeSet,
898 maybe_unused_extern_crates: Vec<(NodeId, Span)>,
900 /// Privacy errors are delayed until the end in order to deduplicate them.
901 privacy_errors: Vec<PrivacyError<'a>>,
902 /// Ambiguity errors are delayed for deduplication.
903 ambiguity_errors: Vec<AmbiguityError<'a>>,
904 /// `use` injections are delayed for better placement and deduplication.
905 use_injections: Vec<UseError<'a>>,
906 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
907 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
909 arenas: &'a ResolverArenas<'a>,
910 dummy_binding: &'a NameBinding<'a>,
912 crate_loader: CrateLoader<'a>,
913 macro_names: FxHashSet<Ident>,
914 builtin_macros: FxHashMap<Name, SyntaxExtension>,
915 registered_attrs: FxHashSet<Ident>,
916 registered_tools: FxHashSet<Ident>,
917 macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
918 all_macros: FxHashMap<Name, Res>,
919 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
920 dummy_ext_bang: Lrc<SyntaxExtension>,
921 dummy_ext_derive: Lrc<SyntaxExtension>,
922 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
923 macro_defs: FxHashMap<ExpnId, DefId>,
924 local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
925 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
926 unused_macros: NodeMap<Span>,
927 proc_macro_stubs: NodeSet,
928 /// Traces collected during macro resolution and validated when it's complete.
929 single_segment_macro_resolutions: Vec<(Ident, MacroKind, ParentScope<'a>,
930 Option<&'a NameBinding<'a>>)>,
931 multi_segment_macro_resolutions: Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>,
933 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
934 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
935 /// Derive macros cannot modify the item themselves and have to store the markers in the global
936 /// context, so they attach the markers to derive container IDs using this resolver table.
937 containers_deriving_copy: FxHashSet<ExpnId>,
938 /// Parent scopes in which the macros were invoked.
939 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
940 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
941 /// Legacy scopes *produced* by expanding the macro invocations,
942 /// include all the `macro_rules` items and other invocations generated by them.
943 output_legacy_scopes: FxHashMap<ExpnId, LegacyScope<'a>>,
945 /// Avoid duplicated errors for "name already defined".
946 name_already_seen: FxHashMap<Name, Span>,
948 potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
950 /// Table for mapping struct IDs into struct constructor IDs,
951 /// it's not used during normal resolution, only for better error reporting.
952 struct_constructors: DefIdMap<(Res, ty::Visibility)>,
954 /// Features enabled for this crate.
955 active_features: FxHashSet<Name>,
957 /// Stores enum visibilities to properly build a reduced graph
958 /// when visiting the correspondent variants.
959 variant_vis: DefIdMap<ty::Visibility>,
961 lint_buffer: lint::LintBuffer,
963 next_node_id: NodeId,
966 /// Nothing really interesting here; it just provides memory for the rest of the crate.
968 pub struct ResolverArenas<'a> {
969 modules: arena::TypedArena<ModuleData<'a>>,
970 local_modules: RefCell<Vec<Module<'a>>>,
971 name_bindings: arena::TypedArena<NameBinding<'a>>,
972 import_directives: arena::TypedArena<ImportDirective<'a>>,
973 name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
974 legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
975 ast_paths: arena::TypedArena<ast::Path>,
978 impl<'a> ResolverArenas<'a> {
979 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
980 let module = self.modules.alloc(module);
981 if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
982 self.local_modules.borrow_mut().push(module);
986 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
987 self.local_modules.borrow()
989 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
990 self.name_bindings.alloc(name_binding)
992 fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
993 -> &'a ImportDirective<'_> {
994 self.import_directives.alloc(import_directive)
996 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
997 self.name_resolutions.alloc(Default::default())
999 fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1000 self.legacy_bindings.alloc(binding)
1002 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1003 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1007 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1008 fn as_mut(&mut self) -> &mut Resolver<'a> { self }
1011 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1012 fn parent(self, id: DefId) -> Option<DefId> {
1014 LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1015 _ => self.cstore().def_key(id).parent,
1016 }.map(|index| DefId { index, ..id })
1020 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1021 /// the resolver is no longer needed as all the relevant information is inline.
1022 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1023 fn cstore(&self) -> &dyn CrateStore {
1027 fn resolve_str_path(
1030 crate_root: Option<Name>,
1031 components: &[Name],
1033 ) -> (ast::Path, Res) {
1034 let root = if crate_root.is_some() {
1039 let segments = iter::once(Ident::with_dummy_span(root))
1041 crate_root.into_iter()
1042 .chain(components.iter().cloned())
1043 .map(Ident::with_dummy_span)
1044 ).map(|i| self.new_ast_path_segment(i)).collect::<Vec<_>>();
1046 let path = ast::Path {
1051 let parent_scope = &ParentScope::module(self.graph_root);
1052 let res = match self.resolve_ast_path(&path, ns, parent_scope) {
1054 Err((span, error)) => {
1055 self.report_error(span, error);
1062 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1063 self.partial_res_map.get(&id).cloned()
1066 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1067 self.import_res_map.get(&id).cloned().unwrap_or_default()
1070 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1071 self.label_res_map.get(&id).cloned()
1074 fn definitions(&mut self) -> &mut Definitions {
1075 &mut self.definitions
1078 fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1079 &mut self.lint_buffer
1082 fn next_node_id(&mut self) -> NodeId {
1087 impl<'a> Resolver<'a> {
1088 pub fn new(session: &'a Session,
1091 metadata_loader: &'a MetadataLoaderDyn,
1092 arenas: &'a ResolverArenas<'a>)
1094 let root_def_id = DefId::local(CRATE_DEF_INDEX);
1095 let root_module_kind = ModuleKind::Def(
1100 let graph_root = arenas.alloc_module(ModuleData {
1101 no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
1102 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1104 let empty_module_kind = ModuleKind::Def(
1109 let empty_module = arenas.alloc_module(ModuleData {
1110 no_implicit_prelude: true,
1119 let mut module_map = FxHashMap::default();
1120 module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1122 let mut definitions = Definitions::default();
1123 definitions.create_root_def(crate_name, session.local_crate_disambiguator());
1125 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> =
1126 session.opts.externs.iter().map(|kv| (Ident::from_str(kv.0), Default::default()))
1129 if !attr::contains_name(&krate.attrs, sym::no_core) {
1130 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1131 if !attr::contains_name(&krate.attrs, sym::no_std) {
1132 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1133 if session.rust_2018() {
1134 extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default());
1139 let (registered_attrs, registered_tools) =
1140 macros::registered_attrs_and_tools(session, &krate.attrs);
1142 let mut invocation_parent_scopes = FxHashMap::default();
1143 invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root));
1145 let mut macro_defs = FxHashMap::default();
1146 macro_defs.insert(ExpnId::root(), root_def_id);
1148 let features = session.features_untracked();
1149 let non_macro_attr =
1150 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1157 // The outermost module has def ID 0; this is not reflected in the
1163 has_self: FxHashSet::default(),
1164 field_names: FxHashMap::default(),
1166 determined_imports: Vec::new(),
1167 indeterminate_imports: Vec::new(),
1169 last_import_segment: false,
1170 blacklisted_binding: None,
1172 primitive_type_table: PrimitiveTypeTable::new(),
1174 partial_res_map: Default::default(),
1175 import_res_map: Default::default(),
1176 label_res_map: Default::default(),
1177 extern_crate_map: Default::default(),
1178 export_map: FxHashMap::default(),
1179 trait_map: Default::default(),
1180 underscore_disambiguator: 0,
1183 block_map: Default::default(),
1184 extern_module_map: FxHashMap::default(),
1185 binding_parent_modules: FxHashMap::default(),
1186 ast_transform_scopes: FxHashMap::default(),
1188 glob_map: Default::default(),
1190 used_imports: FxHashSet::default(),
1191 maybe_unused_trait_imports: Default::default(),
1192 maybe_unused_extern_crates: Vec::new(),
1194 privacy_errors: Vec::new(),
1195 ambiguity_errors: Vec::new(),
1196 use_injections: Vec::new(),
1197 macro_expanded_macro_export_errors: BTreeSet::new(),
1200 dummy_binding: arenas.alloc_name_binding(NameBinding {
1201 kind: NameBindingKind::Res(Res::Err, false),
1203 expansion: ExpnId::root(),
1205 vis: ty::Visibility::Public,
1208 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1209 macro_names: FxHashSet::default(),
1210 builtin_macros: Default::default(),
1213 macro_use_prelude: FxHashMap::default(),
1214 all_macros: FxHashMap::default(),
1215 macro_map: FxHashMap::default(),
1216 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1217 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1218 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1219 invocation_parent_scopes,
1220 output_legacy_scopes: Default::default(),
1222 local_macro_def_scopes: FxHashMap::default(),
1223 name_already_seen: FxHashMap::default(),
1224 potentially_unused_imports: Vec::new(),
1225 struct_constructors: Default::default(),
1226 unused_macros: Default::default(),
1227 proc_macro_stubs: Default::default(),
1228 single_segment_macro_resolutions: Default::default(),
1229 multi_segment_macro_resolutions: Default::default(),
1230 builtin_attrs: Default::default(),
1231 containers_deriving_copy: Default::default(),
1233 features.declared_lib_features.iter().map(|(feat, ..)| *feat)
1234 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1236 variant_vis: Default::default(),
1237 lint_buffer: lint::LintBuffer::default(),
1238 next_node_id: NodeId::from_u32(1),
1242 pub fn next_node_id(&mut self) -> NodeId {
1243 let next = self.next_node_id.as_usize()
1245 .expect("input too large; ran out of NodeIds");
1246 self.next_node_id = ast::NodeId::from_usize(next);
1250 pub fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1251 &mut self.lint_buffer
1254 pub fn arenas() -> ResolverArenas<'a> {
1258 pub fn into_outputs(self) -> ResolverOutputs {
1260 definitions: self.definitions,
1261 cstore: Box::new(self.crate_loader.into_cstore()),
1262 extern_crate_map: self.extern_crate_map,
1263 export_map: self.export_map,
1264 trait_map: self.trait_map,
1265 glob_map: self.glob_map,
1266 maybe_unused_trait_imports: self.maybe_unused_trait_imports,
1267 maybe_unused_extern_crates: self.maybe_unused_extern_crates,
1268 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1269 (ident.name, entry.introduced_by_item)
1274 pub fn clone_outputs(&self) -> ResolverOutputs {
1276 definitions: self.definitions.clone(),
1277 cstore: Box::new(self.cstore().clone()),
1278 extern_crate_map: self.extern_crate_map.clone(),
1279 export_map: self.export_map.clone(),
1280 trait_map: self.trait_map.clone(),
1281 glob_map: self.glob_map.clone(),
1282 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1283 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1284 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1285 (ident.name, entry.introduced_by_item)
1290 pub fn cstore(&self) -> &CStore {
1291 self.crate_loader.cstore()
1294 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1295 self.non_macro_attrs[mark_used as usize].clone()
1298 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1300 MacroKind::Bang => self.dummy_ext_bang.clone(),
1301 MacroKind::Derive => self.dummy_ext_derive.clone(),
1302 MacroKind::Attr => self.non_macro_attr(true),
1306 /// Runs the function on each namespace.
1307 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1313 fn is_builtin_macro(&mut self, res: Res) -> bool {
1314 self.get_macro(res).map_or(false, |ext| ext.is_builtin)
1317 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1319 match self.macro_defs.get(&ctxt.outer_expn()) {
1320 Some(&def_id) => return def_id,
1321 None => ctxt.remove_mark(),
1326 /// Entry point to crate resolution.
1327 pub fn resolve_crate(&mut self, krate: &Crate) {
1329 self.session.prof.generic_activity("resolve_crate");
1331 ImportResolver { r: self }.finalize_imports();
1332 self.finalize_macro_resolutions();
1334 self.late_resolve_crate(krate);
1336 self.check_unused(krate);
1337 self.report_errors(krate);
1338 self.crate_loader.postprocess(krate);
1345 normal_ancestor_id: DefId,
1349 let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span);
1350 self.arenas.alloc_module(module)
1353 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1354 let ident = ident.modern();
1355 let disambiguator = if ident.name == kw::Underscore {
1356 self.underscore_disambiguator += 1;
1357 self.underscore_disambiguator
1361 BindingKey { ident, ns, disambiguator }
1364 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1365 if module.populate_on_access.get() {
1366 module.populate_on_access.set(false);
1367 self.build_reduced_graph_external(module);
1369 &module.lazy_resolutions
1372 fn resolution(&mut self, module: Module<'a>, key: BindingKey)
1373 -> &'a RefCell<NameResolution<'a>> {
1374 *self.resolutions(module).borrow_mut().entry(key)
1375 .or_insert_with(|| self.arenas.alloc_name_resolution())
1378 fn record_use(&mut self, ident: Ident, ns: Namespace,
1379 used_binding: &'a NameBinding<'a>, is_lexical_scope: bool) {
1380 if let Some((b2, kind)) = used_binding.ambiguity {
1381 self.ambiguity_errors.push(AmbiguityError {
1382 kind, ident, b1: used_binding, b2,
1383 misc1: AmbiguityErrorMisc::None,
1384 misc2: AmbiguityErrorMisc::None,
1387 if let NameBindingKind::Import { directive, binding, ref used } = used_binding.kind {
1388 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1389 // but not introduce it, as used if they are accessed from lexical scope.
1390 if is_lexical_scope {
1391 if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
1392 if let Some(crate_item) = entry.extern_crate_item {
1393 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1400 directive.used.set(true);
1401 self.used_imports.insert((directive.id, ns));
1402 self.add_to_glob_map(&directive, ident);
1403 self.record_use(ident, ns, binding, false);
1408 fn add_to_glob_map(&mut self, directive: &ImportDirective<'_>, ident: Ident) {
1409 if directive.is_glob() {
1410 self.glob_map.entry(directive.id).or_default().insert(ident.name);
1414 /// A generic scope visitor.
1415 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1416 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1419 scope_set: ScopeSet,
1420 parent_scope: &ParentScope<'a>,
1422 mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>,
1424 // General principles:
1425 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1426 // built into the language or standard library. This way we can add new names into the
1427 // language or standard library without breaking user code.
1428 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1429 // Places to search (in order of decreasing priority):
1431 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1432 // (open set, not controlled).
1433 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1434 // (open, not controlled).
1435 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1436 // 4. Tool modules (closed, controlled right now, but not in the future).
1437 // 5. Standard library prelude (de-facto closed, controlled).
1438 // 6. Language prelude (closed, controlled).
1440 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1441 // (open set, not controlled).
1442 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1443 // (open, not controlled).
1444 // 3. Standard library prelude (de-facto closed, controlled).
1446 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1447 // are currently reported as errors. They should be higher in priority than preludes
1448 // and probably even names in modules according to the "general principles" above. They
1449 // also should be subject to restricted shadowing because are effectively produced by
1450 // derives (you need to resolve the derive first to add helpers into scope), but they
1451 // should be available before the derive is expanded for compatibility.
1452 // It's mess in general, so we are being conservative for now.
1453 // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
1454 // priority than prelude macros, but create ambiguities with macros in modules.
1455 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1456 // (open, not controlled). Have higher priority than prelude macros, but create
1457 // ambiguities with `macro_rules`.
1458 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1459 // 4a. User-defined prelude from macro-use
1460 // (open, the open part is from macro expansions, not controlled).
1461 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1462 // 4c. Standard library prelude (de-facto closed, controlled).
1463 // 6. Language prelude: builtin attributes (closed, controlled).
1464 // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
1465 // but introduced by legacy plugins using `register_attribute`. Priority is somewhere
1466 // in prelude, not sure where exactly (creates ambiguities with any other prelude names).
1468 let rust_2015 = ident.span.rust_2015();
1469 let (ns, is_absolute_path) = match scope_set {
1470 ScopeSet::All(ns, _) => (ns, false),
1471 ScopeSet::AbsolutePath(ns) => (ns, true),
1472 ScopeSet::Macro(_) => (MacroNS, false),
1474 // Jump out of trait or enum modules, they do not act as scopes.
1475 let module = parent_scope.module.nearest_item_scope();
1476 let mut scope = match ns {
1477 _ if is_absolute_path => Scope::CrateRoot,
1478 TypeNS | ValueNS => Scope::Module(module),
1479 MacroNS => Scope::DeriveHelpers,
1481 let mut ident = ident.modern();
1482 let mut use_prelude = !module.no_implicit_prelude;
1485 let visit = match scope {
1486 Scope::DeriveHelpers => true,
1487 Scope::MacroRules(..) => true,
1488 Scope::CrateRoot => true,
1489 Scope::Module(..) => true,
1490 Scope::RegisteredAttrs => use_prelude,
1491 Scope::MacroUsePrelude => use_prelude || rust_2015,
1492 Scope::BuiltinAttrs => true,
1493 Scope::LegacyPluginHelpers => use_prelude || rust_2015,
1494 Scope::ExternPrelude => use_prelude || is_absolute_path,
1495 Scope::ToolPrelude => use_prelude,
1496 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1497 Scope::BuiltinTypes => true,
1501 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) {
1502 return break_result;
1506 scope = match scope {
1507 Scope::DeriveHelpers =>
1508 Scope::MacroRules(parent_scope.legacy),
1509 Scope::MacroRules(legacy_scope) => match legacy_scope {
1510 LegacyScope::Binding(binding) => Scope::MacroRules(
1511 binding.parent_legacy_scope
1513 LegacyScope::Invocation(invoc_id) => Scope::MacroRules(
1514 self.output_legacy_scopes.get(&invoc_id).cloned()
1515 .unwrap_or(self.invocation_parent_scopes[&invoc_id].legacy)
1517 LegacyScope::Empty => Scope::Module(module),
1519 Scope::CrateRoot => match ns {
1521 ident.span.adjust(ExpnId::root());
1522 Scope::ExternPrelude
1524 ValueNS | MacroNS => break,
1526 Scope::Module(module) => {
1527 use_prelude = !module.no_implicit_prelude;
1528 match self.hygienic_lexical_parent(module, &mut ident.span) {
1529 Some(parent_module) => Scope::Module(parent_module),
1531 ident.span.adjust(ExpnId::root());
1533 TypeNS => Scope::ExternPrelude,
1534 ValueNS => Scope::StdLibPrelude,
1535 MacroNS => Scope::RegisteredAttrs,
1540 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1541 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1542 Scope::BuiltinAttrs => Scope::LegacyPluginHelpers,
1543 Scope::LegacyPluginHelpers => break, // nowhere else to search
1544 Scope::ExternPrelude if is_absolute_path => break,
1545 Scope::ExternPrelude => Scope::ToolPrelude,
1546 Scope::ToolPrelude => Scope::StdLibPrelude,
1547 Scope::StdLibPrelude => match ns {
1548 TypeNS => Scope::BuiltinTypes,
1549 ValueNS => break, // nowhere else to search
1550 MacroNS => Scope::BuiltinAttrs,
1552 Scope::BuiltinTypes => break, // nowhere else to search
1559 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1560 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1561 /// `ident` in the first scope that defines it (or None if no scopes define it).
1563 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1564 /// the items are defined in the block. For example,
1567 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1570 /// g(); // This resolves to the local variable `g` since it shadows the item.
1574 /// Invariant: This must only be called during main resolution, not during
1575 /// import resolution.
1576 fn resolve_ident_in_lexical_scope(&mut self,
1579 parent_scope: &ParentScope<'a>,
1580 record_used_id: Option<NodeId>,
1583 -> Option<LexicalScopeBinding<'a>> {
1584 assert!(ns == TypeNS || ns == ValueNS);
1585 if ident.name == kw::Invalid {
1586 return Some(LexicalScopeBinding::Res(Res::Err));
1588 let (general_span, modern_span) = if ident.name == kw::SelfUpper {
1589 // FIXME(jseyfried) improve `Self` hygiene
1590 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1591 (empty_span, empty_span)
1592 } else if ns == TypeNS {
1593 let modern_span = ident.span.modern();
1594 (modern_span, modern_span)
1596 (ident.span.modern_and_legacy(), ident.span.modern())
1598 ident.span = general_span;
1599 let modern_ident = Ident { span: modern_span, ..ident };
1601 // Walk backwards up the ribs in scope.
1602 let record_used = record_used_id.is_some();
1603 let mut module = self.graph_root;
1604 for i in (0 .. ribs.len()).rev() {
1605 debug!("walk rib\n{:?}", ribs[i].bindings);
1606 // Use the rib kind to determine whether we are resolving parameters
1607 // (modern hygiene) or local variables (legacy hygiene).
1608 let rib_ident = if ribs[i].kind.contains_params() {
1613 if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() {
1614 // The ident resolves to a type parameter or local variable.
1615 return Some(LexicalScopeBinding::Res(
1616 self.validate_res_from_ribs(i, rib_ident, res, record_used, path_span, ribs),
1620 module = match ribs[i].kind {
1621 ModuleRibKind(module) => module,
1622 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1623 // If an invocation of this macro created `ident`, give up on `ident`
1624 // and switch to `ident`'s source from the macro definition.
1625 ident.span.remove_mark();
1632 let item = self.resolve_ident_in_module_unadjusted(
1633 ModuleOrUniformRoot::Module(module),
1640 if let Ok(binding) = item {
1641 // The ident resolves to an item.
1642 return Some(LexicalScopeBinding::Item(binding));
1646 ModuleKind::Block(..) => {}, // We can see through blocks
1651 ident = modern_ident;
1652 let mut poisoned = None;
1654 let opt_module = if let Some(node_id) = record_used_id {
1655 self.hygienic_lexical_parent_with_compatibility_fallback(module, &mut ident.span,
1656 node_id, &mut poisoned)
1658 self.hygienic_lexical_parent(module, &mut ident.span)
1660 module = unwrap_or!(opt_module, break);
1661 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1662 let result = self.resolve_ident_in_module_unadjusted(
1663 ModuleOrUniformRoot::Module(module),
1666 adjusted_parent_scope,
1673 if let Some(node_id) = poisoned {
1674 self.lint_buffer.buffer_lint_with_diagnostic(
1675 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1676 node_id, ident.span,
1677 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1678 lint::builtin::BuiltinLintDiagnostics::
1679 ProcMacroDeriveResolutionFallback(ident.span),
1682 return Some(LexicalScopeBinding::Item(binding))
1684 Err(Determined) => continue,
1685 Err(Undetermined) =>
1686 span_bug!(ident.span, "undetermined resolution during main resolution pass"),
1690 if !module.no_implicit_prelude {
1691 ident.span.adjust(ExpnId::root());
1693 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1694 return Some(LexicalScopeBinding::Item(binding));
1696 if let Some(ident) = self.registered_tools.get(&ident) {
1697 let binding = (Res::ToolMod, ty::Visibility::Public,
1698 ident.span, ExpnId::root()).to_name_binding(self.arenas);
1699 return Some(LexicalScopeBinding::Item(binding));
1702 if let Some(prelude) = self.prelude {
1703 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1704 ModuleOrUniformRoot::Module(prelude),
1711 return Some(LexicalScopeBinding::Item(binding));
1719 fn hygienic_lexical_parent(&mut self, module: Module<'a>, span: &mut Span)
1720 -> Option<Module<'a>> {
1721 if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1722 return Some(self.macro_def_scope(span.remove_mark()));
1725 if let ModuleKind::Block(..) = module.kind {
1726 return Some(module.parent.unwrap().nearest_item_scope());
1732 fn hygienic_lexical_parent_with_compatibility_fallback(&mut self, module: Module<'a>,
1733 span: &mut Span, node_id: NodeId,
1734 poisoned: &mut Option<NodeId>)
1735 -> Option<Module<'a>> {
1736 if let module @ Some(..) = self.hygienic_lexical_parent(module, span) {
1740 // We need to support the next case under a deprecation warning
1743 // ---- begin: this comes from a proc macro derive
1744 // mod implementation_details {
1745 // // Note that `MyStruct` is not in scope here.
1746 // impl SomeTrait for MyStruct { ... }
1750 // So we have to fall back to the module's parent during lexical resolution in this case.
1751 if let Some(parent) = module.parent {
1752 // Inner module is inside the macro, parent module is outside of the macro.
1753 if module.expansion != parent.expansion &&
1754 module.expansion.is_descendant_of(parent.expansion) {
1755 // The macro is a proc macro derive
1756 if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
1757 if let Some(ext) = self.get_macro_by_def_id(def_id) {
1758 if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
1759 if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1760 *poisoned = Some(node_id);
1761 return module.parent;
1772 fn resolve_ident_in_module(
1774 module: ModuleOrUniformRoot<'a>,
1777 parent_scope: &ParentScope<'a>,
1780 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1781 self.resolve_ident_in_module_ext(
1782 module, ident, ns, parent_scope, record_used, path_span
1783 ).map_err(|(determinacy, _)| determinacy)
1786 fn resolve_ident_in_module_ext(
1788 module: ModuleOrUniformRoot<'a>,
1791 parent_scope: &ParentScope<'a>,
1794 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
1795 let tmp_parent_scope;
1796 let mut adjusted_parent_scope = parent_scope;
1798 ModuleOrUniformRoot::Module(m) => {
1799 if let Some(def) = ident.span.modernize_and_adjust(m.expansion) {
1801 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
1802 adjusted_parent_scope = &tmp_parent_scope;
1805 ModuleOrUniformRoot::ExternPrelude => {
1806 ident.span.modernize_and_adjust(ExpnId::root());
1808 ModuleOrUniformRoot::CrateRootAndExternPrelude |
1809 ModuleOrUniformRoot::CurrentScope => {
1813 let result = self.resolve_ident_in_module_unadjusted_ext(
1814 module, ident, ns, adjusted_parent_scope, false, record_used, path_span,
1819 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
1820 let mut ctxt = ident.span.ctxt();
1821 let mark = if ident.name == kw::DollarCrate {
1822 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
1823 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
1824 // as described in `SyntaxContext::apply_mark`, so we ignore prepended modern marks.
1825 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
1826 // definitions actually produced by `macro` and `macro` definitions produced by
1827 // `macro_rules!`, but at least such configurations are not stable yet.
1828 ctxt = ctxt.modern_and_legacy();
1829 let mut iter = ctxt.marks().into_iter().rev().peekable();
1830 let mut result = None;
1831 // Find the last modern mark from the end if it exists.
1832 while let Some(&(mark, transparency)) = iter.peek() {
1833 if transparency == Transparency::Opaque {
1834 result = Some(mark);
1840 // Then find the last legacy mark from the end if it exists.
1841 for (mark, transparency) in iter {
1842 if transparency == Transparency::SemiTransparent {
1843 result = Some(mark);
1850 ctxt = ctxt.modern();
1851 ctxt.adjust(ExpnId::root())
1853 let module = match mark {
1854 Some(def) => self.macro_def_scope(def),
1855 None => return self.graph_root,
1857 self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
1860 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
1861 let mut module = self.get_module(module.normal_ancestor_id);
1862 while module.span.ctxt().modern() != *ctxt {
1863 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
1864 module = self.get_module(parent.normal_ancestor_id);
1872 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1873 parent_scope: &ParentScope<'a>,
1876 crate_lint: CrateLint,
1877 ) -> PathResult<'a> {
1878 self.resolve_path_with_ribs(
1879 path, opt_ns, parent_scope, record_used, path_span, crate_lint, None
1883 fn resolve_path_with_ribs(
1886 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1887 parent_scope: &ParentScope<'a>,
1890 crate_lint: CrateLint,
1891 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
1892 ) -> PathResult<'a> {
1893 let mut module = None;
1894 let mut allow_super = true;
1895 let mut second_binding = None;
1898 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
1899 path_span={:?}, crate_lint={:?})",
1907 for (i, &Segment { ident, id }) in path.iter().enumerate() {
1908 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
1909 let record_segment_res = |this: &mut Self, res| {
1911 if let Some(id) = id {
1912 if !this.partial_res_map.contains_key(&id) {
1913 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
1914 this.record_partial_res(id, PartialRes::new(res));
1920 let is_last = i == path.len() - 1;
1921 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
1922 let name = ident.name;
1924 allow_super &= ns == TypeNS &&
1925 (name == kw::SelfLower ||
1929 if allow_super && name == kw::Super {
1930 let mut ctxt = ident.span.ctxt().modern();
1931 let self_module = match i {
1932 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
1934 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
1938 if let Some(self_module) = self_module {
1939 if let Some(parent) = self_module.parent {
1940 module = Some(ModuleOrUniformRoot::Module(
1941 self.resolve_self(&mut ctxt, parent)));
1945 let msg = "there are too many initial `super`s.".to_string();
1946 return PathResult::Failed {
1950 is_error_from_last_segment: false,
1954 if name == kw::SelfLower {
1955 let mut ctxt = ident.span.ctxt().modern();
1956 module = Some(ModuleOrUniformRoot::Module(
1957 self.resolve_self(&mut ctxt, parent_scope.module)));
1960 if name == kw::PathRoot && ident.span.rust_2018() {
1961 module = Some(ModuleOrUniformRoot::ExternPrelude);
1964 if name == kw::PathRoot &&
1965 ident.span.rust_2015() && self.session.rust_2018() {
1966 // `::a::b` from 2015 macro on 2018 global edition
1967 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
1970 if name == kw::PathRoot ||
1971 name == kw::Crate ||
1972 name == kw::DollarCrate {
1973 // `::a::b`, `crate::a::b` or `$crate::a::b`
1974 module = Some(ModuleOrUniformRoot::Module(
1975 self.resolve_crate_root(ident)));
1981 // Report special messages for path segment keywords in wrong positions.
1982 if ident.is_path_segment_keyword() && i != 0 {
1983 let name_str = if name == kw::PathRoot {
1984 "crate root".to_string()
1986 format!("`{}`", name)
1988 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
1989 format!("global paths cannot start with {}", name_str)
1991 format!("{} in paths can only be used in start position", name_str)
1993 return PathResult::Failed {
1997 is_error_from_last_segment: false,
2001 let binding = if let Some(module) = module {
2002 self.resolve_ident_in_module(
2003 module, ident, ns, parent_scope, record_used, path_span
2005 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2006 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2007 self.early_resolve_ident_in_lexical_scope(ident, scopes, parent_scope, record_used,
2008 record_used, path_span)
2010 let record_used_id =
2011 if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };
2012 match self.resolve_ident_in_lexical_scope(
2013 ident, ns, parent_scope, record_used_id, path_span, &ribs.unwrap()[ns]
2015 // we found a locally-imported or available item/module
2016 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2017 // we found a local variable or type param
2018 Some(LexicalScopeBinding::Res(res))
2019 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2020 record_segment_res(self, res);
2021 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2025 _ => Err(Determinacy::determined(record_used)),
2032 second_binding = Some(binding);
2034 let res = binding.res();
2035 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2036 if let Some(next_module) = binding.module() {
2037 module = Some(ModuleOrUniformRoot::Module(next_module));
2038 record_segment_res(self, res);
2039 } else if res == Res::ToolMod && i + 1 != path.len() {
2040 if binding.is_import() {
2041 self.session.struct_span_err(
2042 ident.span, "cannot use a tool module through an import"
2044 binding.span, "the tool module imported here"
2047 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2048 return PathResult::NonModule(PartialRes::new(res));
2049 } else if res == Res::Err {
2050 return PathResult::NonModule(PartialRes::new(Res::Err));
2051 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2052 self.lint_if_path_starts_with_module(
2058 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2059 res, path.len() - i - 1
2062 let label = format!(
2063 "`{}` is {} {}, not a module",
2069 return PathResult::Failed {
2073 is_error_from_last_segment: is_last,
2077 Err(Undetermined) => return PathResult::Indeterminate,
2078 Err(Determined) => {
2079 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2080 if opt_ns.is_some() && !module.is_normal() {
2081 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2082 module.res().unwrap(), path.len() - i
2086 let module_res = match module {
2087 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2090 let (label, suggestion) = if module_res == self.graph_root.res() {
2091 let is_mod = |res| {
2092 match res { Res::Def(DefKind::Mod, _) => true, _ => false }
2094 let mut candidates =
2095 self.lookup_import_candidates(ident, TypeNS, is_mod);
2096 candidates.sort_by_cached_key(|c| {
2097 (c.path.segments.len(), pprust::path_to_string(&c.path))
2099 if let Some(candidate) = candidates.get(0) {
2101 String::from("unresolved import"),
2103 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2104 String::from("a similar path exists"),
2105 Applicability::MaybeIncorrect,
2108 } else if !ident.is_reserved() {
2109 (format!("maybe a missing crate `{}`?", ident), None)
2111 // the parser will already have complained about the keyword being used
2112 return PathResult::NonModule(PartialRes::new(Res::Err));
2115 (format!("use of undeclared type or module `{}`", ident), None)
2117 (format!("could not find `{}` in `{}`", ident, path[i - 1].ident), None)
2119 return PathResult::Failed {
2123 is_error_from_last_segment: is_last,
2129 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2131 PathResult::Module(match module {
2132 Some(module) => module,
2133 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2134 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2138 fn lint_if_path_starts_with_module(
2140 crate_lint: CrateLint,
2143 second_binding: Option<&NameBinding<'_>>,
2145 let (diag_id, diag_span) = match crate_lint {
2146 CrateLint::No => return,
2147 CrateLint::SimplePath(id) => (id, path_span),
2148 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2149 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2152 let first_name = match path.get(0) {
2153 // In the 2018 edition this lint is a hard error, so nothing to do
2154 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2158 // We're only interested in `use` paths which should start with
2159 // `{{root}}` currently.
2160 if first_name != kw::PathRoot {
2165 // If this import looks like `crate::...` it's already good
2166 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2167 // Otherwise go below to see if it's an extern crate
2169 // If the path has length one (and it's `PathRoot` most likely)
2170 // then we don't know whether we're gonna be importing a crate or an
2171 // item in our crate. Defer this lint to elsewhere
2175 // If the first element of our path was actually resolved to an
2176 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2177 // warning, this looks all good!
2178 if let Some(binding) = second_binding {
2179 if let NameBindingKind::Import { directive: d, .. } = binding.kind {
2180 // Careful: we still want to rewrite paths from
2181 // renamed extern crates.
2182 if let ImportDirectiveSubclass::ExternCrate { source: None, .. } = d.subclass {
2188 let diag = lint::builtin::BuiltinLintDiagnostics
2189 ::AbsPathWithModule(diag_span);
2190 self.lint_buffer.buffer_lint_with_diagnostic(
2191 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2193 "absolute paths must start with `self`, `super`, \
2194 `crate`, or an external crate name in the 2018 edition",
2198 // Validate a local resolution (from ribs).
2199 fn validate_res_from_ribs(
2206 all_ribs: &[Rib<'a>],
2208 debug!("validate_res_from_ribs({:?})", res);
2209 let ribs = &all_ribs[rib_index + 1..];
2211 // An invalid forward use of a type parameter from a previous default.
2212 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2214 let res_error = if rib_ident.name == kw::SelfUpper {
2215 ResolutionError::SelfInTyParamDefault
2217 ResolutionError::ForwardDeclaredTyParam
2219 self.report_error(span, res_error);
2221 assert_eq!(res, Res::Err);
2227 use ResolutionError::*;
2228 let mut res_err = None;
2232 NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2233 ForwardTyParamBanRibKind => {
2234 // Nothing to do. Continue.
2236 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2237 // This was an attempt to access an upvar inside a
2238 // named function item. This is not allowed, so we
2241 // We don't immediately trigger a resolve error, because
2242 // we want certain other resolution errors (namely those
2243 // emitted for `ConstantItemRibKind` below) to take
2245 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2248 ConstantItemRibKind => {
2249 // Still doesn't deal with upvars
2251 self.report_error(span, AttemptToUseNonConstantValueInConstant);
2257 if let Some(res_err) = res_err {
2258 self.report_error(span, res_err);
2262 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2264 let has_generic_params = match rib.kind {
2265 NormalRibKind | AssocItemRibKind |
2266 ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2267 ConstantItemRibKind => {
2268 // Nothing to do. Continue.
2271 // This was an attempt to use a type parameter outside its scope.
2272 ItemRibKind(has_generic_params) => has_generic_params,
2273 FnItemRibKind => HasGenericParams::Yes,
2277 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2278 res, has_generic_params));
2283 Res::Def(DefKind::ConstParam, _) => {
2284 let mut ribs = ribs.iter().peekable();
2285 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2286 // When declaring const parameters inside function signatures, the first rib
2287 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2288 // (spuriously) conflicting with the const param.
2292 let has_generic_params = match rib.kind {
2293 ItemRibKind(has_generic_params) => has_generic_params,
2294 FnItemRibKind => HasGenericParams::Yes,
2298 // This was an attempt to use a const parameter outside its scope.
2300 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2301 res, has_generic_params));
2311 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2312 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2313 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2314 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2318 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2319 vis.is_accessible_from(module.normal_ancestor_id, self)
2322 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2323 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2324 if !ptr::eq(module, old_module) {
2325 span_bug!(binding.span, "parent module is reset for binding");
2330 fn disambiguate_legacy_vs_modern(
2332 legacy: &'a NameBinding<'a>,
2333 modern: &'a NameBinding<'a>,
2335 // Some non-controversial subset of ambiguities "modern macro name" vs "macro_rules"
2336 // is disambiguated to mitigate regressions from macro modularization.
2337 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2338 match (self.binding_parent_modules.get(&PtrKey(legacy)),
2339 self.binding_parent_modules.get(&PtrKey(modern))) {
2340 (Some(legacy), Some(modern)) =>
2341 legacy.normal_ancestor_id == modern.normal_ancestor_id &&
2342 modern.is_ancestor_of(legacy),
2347 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
2349 if b.span.is_dummy() {
2350 let add_built_in = match b.res() {
2351 // These already contain the "built-in" prefix or look bad with it.
2352 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
2355 let (built_in, from) = if from_prelude {
2356 ("", " from prelude")
2357 } else if b.is_extern_crate() && !b.is_import() &&
2358 self.session.opts.externs.get(&ident.as_str()).is_some() {
2359 ("", " passed with `--extern`")
2360 } else if add_built_in {
2366 let article = if built_in.is_empty() { res.article() } else { "a" };
2367 format!("{a}{built_in} {thing}{from}",
2368 a = article, thing = res.descr(), built_in = built_in, from = from)
2370 let introduced = if b.is_import() { "imported" } else { "defined" };
2371 format!("the {thing} {introduced} here",
2372 thing = res.descr(), introduced = introduced)
2376 fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
2377 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
2378 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
2379 // We have to print the span-less alternative first, otherwise formatting looks bad.
2380 (b2, b1, misc2, misc1, true)
2382 (b1, b2, misc1, misc2, false)
2385 let mut err = struct_span_err!(self.session, ident.span, E0659,
2386 "`{ident}` is ambiguous ({why})",
2387 ident = ident, why = kind.descr());
2388 err.span_label(ident.span, "ambiguous name");
2390 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
2391 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
2392 let note_msg = format!("`{ident}` could{also} refer to {what}",
2393 ident = ident, also = also, what = what);
2395 let thing = b.res().descr();
2396 let mut help_msgs = Vec::new();
2397 if b.is_glob_import() && (kind == AmbiguityKind::GlobVsGlob ||
2398 kind == AmbiguityKind::GlobVsExpanded ||
2399 kind == AmbiguityKind::GlobVsOuter &&
2400 swapped != also.is_empty()) {
2401 help_msgs.push(format!("consider adding an explicit import of \
2402 `{ident}` to disambiguate", ident = ident))
2404 if b.is_extern_crate() && ident.span.rust_2018() {
2405 help_msgs.push(format!(
2406 "use `::{ident}` to refer to this {thing} unambiguously",
2407 ident = ident, thing = thing,
2410 if misc == AmbiguityErrorMisc::SuggestCrate {
2411 help_msgs.push(format!(
2412 "use `crate::{ident}` to refer to this {thing} unambiguously",
2413 ident = ident, thing = thing,
2415 } else if misc == AmbiguityErrorMisc::SuggestSelf {
2416 help_msgs.push(format!(
2417 "use `self::{ident}` to refer to this {thing} unambiguously",
2418 ident = ident, thing = thing,
2422 err.span_note(b.span, ¬e_msg);
2423 for (i, help_msg) in help_msgs.iter().enumerate() {
2424 let or = if i == 0 { "" } else { "or " };
2425 err.help(&format!("{}{}", or, help_msg));
2429 could_refer_to(b1, misc1, "");
2430 could_refer_to(b2, misc2, " also");
2434 fn report_errors(&mut self, krate: &Crate) {
2435 self.report_with_use_injections(krate);
2437 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2438 let msg = "macro-expanded `macro_export` macros from the current crate \
2439 cannot be referred to by absolute paths";
2440 self.lint_buffer.buffer_lint_with_diagnostic(
2441 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2442 CRATE_NODE_ID, span_use, msg,
2443 lint::builtin::BuiltinLintDiagnostics::
2444 MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2448 for ambiguity_error in &self.ambiguity_errors {
2449 self.report_ambiguity_error(ambiguity_error);
2452 let mut reported_spans = FxHashSet::default();
2453 for &PrivacyError(dedup_span, ident, binding) in &self.privacy_errors {
2454 if reported_spans.insert(dedup_span) {
2455 let session = &self.session;
2456 let mk_struct_span_error = |is_constructor| {
2461 "{}{} `{}` is private",
2462 binding.res().descr(),
2463 if is_constructor { " constructor"} else { "" },
2468 let mut err = if let NameBindingKind::Res(
2469 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _
2471 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
2472 if let Some(fields) = self.field_names.get(&def_id) {
2473 let mut err = mk_struct_span_error(true);
2474 let first_field = fields.first().expect("empty field list in the map");
2476 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
2477 "a constructor is private if any of the fields is private",
2481 mk_struct_span_error(false)
2484 mk_struct_span_error(false)
2492 fn report_with_use_injections(&mut self, krate: &Crate) {
2493 for UseError { mut err, candidates, node_id, better } in self.use_injections.drain(..) {
2494 let (span, found_use) = UsePlacementFinder::check(krate, node_id);
2495 if !candidates.is_empty() {
2496 diagnostics::show_candidates(&mut err, span, &candidates, better, found_use);
2502 fn report_conflict<'b>(&mut self,
2506 new_binding: &NameBinding<'b>,
2507 old_binding: &NameBinding<'b>) {
2508 // Error on the second of two conflicting names
2509 if old_binding.span.lo() > new_binding.span.lo() {
2510 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2513 let container = match parent.kind {
2514 ModuleKind::Def(DefKind::Mod, _, _) => "module",
2515 ModuleKind::Def(DefKind::Trait, _, _) => "trait",
2516 ModuleKind::Block(..) => "block",
2520 let old_noun = match old_binding.is_import() {
2522 false => "definition",
2525 let new_participle = match new_binding.is_import() {
2530 let (name, span) = (ident.name, self.session.source_map().def_span(new_binding.span));
2532 if let Some(s) = self.name_already_seen.get(&name) {
2538 let old_kind = match (ns, old_binding.module()) {
2539 (ValueNS, _) => "value",
2540 (MacroNS, _) => "macro",
2541 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2542 (TypeNS, Some(module)) if module.is_normal() => "module",
2543 (TypeNS, Some(module)) if module.is_trait() => "trait",
2544 (TypeNS, _) => "type",
2547 let msg = format!("the name `{}` is defined multiple times", name);
2549 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2550 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2551 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2552 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2553 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2555 _ => match (old_binding.is_import(), new_binding.is_import()) {
2556 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2557 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2558 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2562 err.note(&format!("`{}` must be defined only once in the {} namespace of this {}",
2567 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2569 self.session.source_map().def_span(old_binding.span),
2570 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2573 // See https://github.com/rust-lang/rust/issues/32354
2574 use NameBindingKind::Import;
2575 let directive = match (&new_binding.kind, &old_binding.kind) {
2576 // If there are two imports where one or both have attributes then prefer removing the
2577 // import without attributes.
2578 (Import { directive: new, .. }, Import { directive: old, .. }) if {
2579 !new_binding.span.is_dummy() && !old_binding.span.is_dummy() &&
2580 (new.has_attributes || old.has_attributes)
2582 if old.has_attributes {
2583 Some((new, new_binding.span, true))
2585 Some((old, old_binding.span, true))
2588 // Otherwise prioritize the new binding.
2589 (Import { directive, .. }, other) if !new_binding.span.is_dummy() =>
2590 Some((directive, new_binding.span, other.is_import())),
2591 (other, Import { directive, .. }) if !old_binding.span.is_dummy() =>
2592 Some((directive, old_binding.span, other.is_import())),
2596 // Check if the target of the use for both bindings is the same.
2597 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2598 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2599 let from_item = self.extern_prelude.get(&ident)
2600 .map(|entry| entry.introduced_by_item)
2602 // Only suggest removing an import if both bindings are to the same def, if both spans
2603 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2604 // been introduced by a item.
2605 let should_remove_import = duplicate && !has_dummy_span &&
2606 ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2609 Some((directive, span, true)) if should_remove_import && directive.is_nested() =>
2610 self.add_suggestion_for_duplicate_nested_use(&mut err, directive, span),
2611 Some((directive, _, true)) if should_remove_import && !directive.is_glob() => {
2612 // Simple case - remove the entire import. Due to the above match arm, this can
2613 // only be a single use so just remove it entirely.
2614 err.tool_only_span_suggestion(
2615 directive.use_span_with_attributes,
2616 "remove unnecessary import",
2618 Applicability::MaybeIncorrect,
2621 Some((directive, span, _)) =>
2622 self.add_suggestion_for_rename_of_use(&mut err, name, directive, span),
2627 self.name_already_seen.insert(name, span);
2630 /// This function adds a suggestion to change the binding name of a new import that conflicts
2631 /// with an existing import.
2633 /// ```ignore (diagnostic)
2634 /// help: you can use `as` to change the binding name of the import
2636 /// LL | use foo::bar as other_bar;
2637 /// | ^^^^^^^^^^^^^^^^^^^^^
2639 fn add_suggestion_for_rename_of_use(
2641 err: &mut DiagnosticBuilder<'_>,
2643 directive: &ImportDirective<'_>,
2646 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
2647 format!("Other{}", name)
2649 format!("other_{}", name)
2652 let mut suggestion = None;
2653 match directive.subclass {
2654 ImportDirectiveSubclass::SingleImport { type_ns_only: true, .. } =>
2655 suggestion = Some(format!("self as {}", suggested_name)),
2656 ImportDirectiveSubclass::SingleImport { source, .. } => {
2657 if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0)
2658 .map(|pos| pos as usize) {
2659 if let Ok(snippet) = self.session.source_map()
2660 .span_to_snippet(binding_span) {
2661 if pos <= snippet.len() {
2662 suggestion = Some(format!(
2666 if snippet.ends_with(";") { ";" } else { "" }
2672 ImportDirectiveSubclass::ExternCrate { source, target, .. } =>
2673 suggestion = Some(format!(
2674 "extern crate {} as {};",
2675 source.unwrap_or(target.name),
2678 _ => unreachable!(),
2681 let rename_msg = "you can use `as` to change the binding name of the import";
2682 if let Some(suggestion) = suggestion {
2683 err.span_suggestion(
2687 Applicability::MaybeIncorrect,
2690 err.span_label(binding_span, rename_msg);
2694 /// This function adds a suggestion to remove a unnecessary binding from an import that is
2695 /// nested. In the following example, this function will be invoked to remove the `a` binding
2696 /// in the second use statement:
2698 /// ```ignore (diagnostic)
2699 /// use issue_52891::a;
2700 /// use issue_52891::{d, a, e};
2703 /// The following suggestion will be added:
2705 /// ```ignore (diagnostic)
2706 /// use issue_52891::{d, a, e};
2707 /// ^-- help: remove unnecessary import
2710 /// If the nested use contains only one import then the suggestion will remove the entire
2713 /// It is expected that the directive provided is a nested import - this isn't checked by the
2714 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
2715 /// as characters expected by span manipulations won't be present.
2716 fn add_suggestion_for_duplicate_nested_use(
2718 err: &mut DiagnosticBuilder<'_>,
2719 directive: &ImportDirective<'_>,
2722 assert!(directive.is_nested());
2723 let message = "remove unnecessary import";
2725 // Two examples will be used to illustrate the span manipulations we're doing:
2727 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
2728 // `a` and `directive.use_span` is `issue_52891::{d, a, e};`.
2729 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
2730 // `a` and `directive.use_span` is `issue_52891::{d, e, a};`.
2732 let (found_closing_brace, span) = find_span_of_binding_until_next_binding(
2733 self.session, binding_span, directive.use_span,
2736 // If there was a closing brace then identify the span to remove any trailing commas from
2737 // previous imports.
2738 if found_closing_brace {
2739 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
2740 err.tool_only_span_suggestion(span, message, String::new(),
2741 Applicability::MaybeIncorrect);
2743 // Remove the entire line if we cannot extend the span back, this indicates a
2744 // `issue_52891::{self}` case.
2745 err.span_suggestion(directive.use_span_with_attributes, message, String::new(),
2746 Applicability::MaybeIncorrect);
2752 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
2755 fn extern_prelude_get(&mut self, ident: Ident, speculative: bool)
2756 -> Option<&'a NameBinding<'a>> {
2757 if ident.is_path_segment_keyword() {
2758 // Make sure `self`, `super` etc produce an error when passed to here.
2761 self.extern_prelude.get(&ident.modern()).cloned().and_then(|entry| {
2762 if let Some(binding) = entry.extern_crate_item {
2763 if !speculative && entry.introduced_by_item {
2764 self.record_use(ident, TypeNS, binding, false);
2768 let crate_id = if !speculative {
2769 self.crate_loader.process_path_extern(ident.name, ident.span)
2770 } else if let Some(crate_id) =
2771 self.crate_loader.maybe_process_path_extern(ident.name, ident.span) {
2776 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
2777 Some((crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
2778 .to_name_binding(self.arenas))
2783 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
2784 /// isn't something that can be returned because it can't be made to live that long,
2785 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
2786 /// just that an error occurred.
2787 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
2788 pub fn resolve_str_path_error(
2789 &mut self, span: Span, path_str: &str, ns: Namespace, module_id: NodeId
2790 ) -> Result<(ast::Path, Res), ()> {
2791 let path = if path_str.starts_with("::") {
2794 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
2796 path_str.split("::").skip(1).map(Ident::from_str)
2798 .map(|i| self.new_ast_path_segment(i))
2806 .map(Ident::from_str)
2807 .map(|i| self.new_ast_path_segment(i))
2811 let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| {
2812 let def_id = self.definitions.local_def_id(module_id);
2813 self.module_map.get(&def_id).copied().unwrap_or(self.graph_root)
2815 let parent_scope = &ParentScope::module(module);
2816 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
2820 // Resolve a path passed from rustdoc or HIR lowering.
2821 fn resolve_ast_path(
2825 parent_scope: &ParentScope<'a>,
2826 ) -> Result<Res, (Span, ResolutionError<'a>)> {
2827 match self.resolve_path(
2828 &Segment::from_path(path), Some(ns), parent_scope, true, path.span, CrateLint::No
2830 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
2831 Ok(module.res().unwrap()),
2832 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
2833 Ok(path_res.base_res()),
2834 PathResult::NonModule(..) => {
2835 Err((path.span, ResolutionError::FailedToResolve {
2836 label: String::from("type-relative paths are not supported in this context"),
2840 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
2841 PathResult::Failed { span, label, suggestion, .. } => {
2842 Err((span, ResolutionError::FailedToResolve {
2850 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
2851 let mut seg = ast::PathSegment::from_ident(ident);
2852 seg.id = self.next_node_id();
2857 pub fn graph_root(&self) -> Module<'a> {
2862 pub fn all_macros(&self) -> &FxHashMap<Name, Res> {
2867 fn names_to_string(names: &[Name]) -> String {
2868 let mut result = String::new();
2869 for (i, name) in names.iter()
2870 .filter(|name| **name != kw::PathRoot)
2873 result.push_str("::");
2875 result.push_str(&name.as_str());
2880 fn path_names_to_string(path: &Path) -> String {
2881 names_to_string(&path.segments.iter()
2882 .map(|seg| seg.ident.name)
2883 .collect::<Vec<_>>())
2886 /// A somewhat inefficient routine to obtain the name of a module.
2887 fn module_to_string(module: Module<'_>) -> Option<String> {
2888 let mut names = Vec::new();
2890 fn collect_mod(names: &mut Vec<Name>, module: Module<'_>) {
2891 if let ModuleKind::Def(.., name) = module.kind {
2892 if let Some(parent) = module.parent {
2894 collect_mod(names, parent);
2897 names.push(Name::intern("<opaque>"));
2898 collect_mod(names, module.parent.unwrap());
2901 collect_mod(&mut names, module);
2903 if names.is_empty() {
2907 Some(names_to_string(&names))
2910 #[derive(Copy, Clone, Debug)]
2912 /// Do not issue the lint.
2915 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
2916 /// In this case, we can take the span of that path.
2919 /// This lint comes from a `use` statement. In this case, what we
2920 /// care about really is the *root* `use` statement; e.g., if we
2921 /// have nested things like `use a::{b, c}`, we care about the
2923 UsePath { root_id: NodeId, root_span: Span },
2925 /// This is the "trait item" from a fully qualified path. For example,
2926 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
2927 /// The `path_span` is the span of the to the trait itself (`X::Y`).
2928 QPathTrait { qpath_id: NodeId, qpath_span: Span },
2932 fn node_id(&self) -> Option<NodeId> {
2934 CrateLint::No => None,
2935 CrateLint::SimplePath(id) |
2936 CrateLint::UsePath { root_id: id, .. } |
2937 CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),