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 use rustc_error_codes::*;
69 type Res = def::Res<NodeId>;
75 mod build_reduced_graph;
83 #[derive(Copy, Clone, PartialEq, Debug)]
84 pub enum Determinacy {
90 fn determined(determined: bool) -> Determinacy {
91 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
95 /// A specific scope in which a name can be looked up.
96 /// This enum is currently used only for early resolution (imports and macros),
97 /// but not for late resolution yet.
98 #[derive(Clone, Copy)]
101 MacroRules(LegacyScope<'a>),
114 /// Names from different contexts may want to visit different subsets of all specific scopes
115 /// with different restrictions when looking up the resolution.
116 /// This enum is currently used only for early resolution (imports and macros),
117 /// but not for late resolution yet.
119 /// All scopes with the given namespace.
120 All(Namespace, /*is_import*/ bool),
121 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
122 AbsolutePath(Namespace),
123 /// All scopes with macro namespace and the given macro kind restriction.
127 /// Everything you need to know about a name's location to resolve it.
128 /// Serves as a starting point for the scope visitor.
129 /// This struct is currently used only for early resolution (imports and macros),
130 /// but not for late resolution yet.
131 #[derive(Clone, Copy, Debug)]
132 pub struct ParentScope<'a> {
135 legacy: LegacyScope<'a>,
136 derives: &'a [ast::Path],
139 impl<'a> ParentScope<'a> {
140 /// Creates a parent scope with the passed argument used as the module scope component,
141 /// and other scope components set to default empty values.
142 pub fn module(module: Module<'a>) -> ParentScope<'a> {
145 expansion: ExpnId::root(),
146 legacy: LegacyScope::Empty,
153 struct BindingError {
155 origin: BTreeSet<Span>,
156 target: BTreeSet<Span>,
160 impl PartialOrd for BindingError {
161 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
162 Some(self.cmp(other))
166 impl PartialEq for BindingError {
167 fn eq(&self, other: &BindingError) -> bool {
168 self.name == other.name
172 impl Ord for BindingError {
173 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
174 self.name.cmp(&other.name)
178 enum ResolutionError<'a> {
179 /// Error E0401: can't use type or const parameters from outer function.
180 GenericParamsFromOuterFunction(Res, HasGenericParams),
181 /// Error E0403: the name is already used for a type or const parameter in this generic
183 NameAlreadyUsedInParameterList(Name, Span),
184 /// Error E0407: method is not a member of trait.
185 MethodNotMemberOfTrait(Name, &'a str),
186 /// Error E0437: type is not a member of trait.
187 TypeNotMemberOfTrait(Name, &'a str),
188 /// Error E0438: const is not a member of trait.
189 ConstNotMemberOfTrait(Name, &'a str),
190 /// Error E0408: variable `{}` is not bound in all patterns.
191 VariableNotBoundInPattern(&'a BindingError),
192 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
193 VariableBoundWithDifferentMode(Name, Span),
194 /// Error E0415: identifier is bound more than once in this parameter list.
195 IdentifierBoundMoreThanOnceInParameterList(&'a str),
196 /// Error E0416: identifier is bound more than once in the same pattern.
197 IdentifierBoundMoreThanOnceInSamePattern(&'a str),
198 /// Error E0426: use of undeclared label.
199 UndeclaredLabel(&'a str, Option<Name>),
200 /// Error E0429: `self` imports are only allowed within a `{ }` list.
201 SelfImportsOnlyAllowedWithin,
202 /// Error E0430: `self` import can only appear once in the list.
203 SelfImportCanOnlyAppearOnceInTheList,
204 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
205 SelfImportOnlyInImportListWithNonEmptyPrefix,
206 /// Error E0433: failed to resolve.
207 FailedToResolve { label: String, suggestion: Option<Suggestion> },
208 /// Error E0434: can't capture dynamic environment in a fn item.
209 CannotCaptureDynamicEnvironmentInFnItem,
210 /// Error E0435: attempt to use a non-constant value in a constant.
211 AttemptToUseNonConstantValueInConstant,
212 /// Error E0530: `X` bindings cannot shadow `Y`s.
213 BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
214 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
215 ForwardDeclaredTyParam, // FIXME(const_generics:defaults)
216 /// Error E0735: type parameters with a default cannot use `Self`
217 SelfInTyParamDefault,
220 // A minimal representation of a path segment. We use this in resolve because
221 // we synthesize 'path segments' which don't have the rest of an AST or HIR
223 #[derive(Clone, Copy, Debug)]
230 fn from_path(path: &Path) -> Vec<Segment> {
231 path.segments.iter().map(|s| s.into()).collect()
234 fn from_ident(ident: Ident) -> Segment {
241 fn names_to_string(segments: &[Segment]) -> String {
242 names_to_string(&segments.iter()
243 .map(|seg| seg.ident.name)
244 .collect::<Vec<_>>())
248 impl<'a> From<&'a ast::PathSegment> for Segment {
249 fn from(seg: &'a ast::PathSegment) -> Segment {
257 struct UsePlacementFinder {
258 target_module: NodeId,
263 impl UsePlacementFinder {
264 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
265 let mut finder = UsePlacementFinder {
270 visit::walk_crate(&mut finder, krate);
271 (finder.span, finder.found_use)
275 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
278 module: &'tcx ast::Mod,
280 _: &[ast::Attribute],
283 if self.span.is_some() {
286 if node_id != self.target_module {
287 visit::walk_mod(self, module);
290 // find a use statement
291 for item in &module.items {
293 ItemKind::Use(..) => {
294 // don't suggest placing a use before the prelude
295 // import or other generated ones
296 if !item.span.from_expansion() {
297 self.span = Some(item.span.shrink_to_lo());
298 self.found_use = true;
302 // don't place use before extern crate
303 ItemKind::ExternCrate(_) => {}
304 // but place them before the first other item
305 _ => if self.span.map_or(true, |span| item.span < span ) {
306 if !item.span.from_expansion() {
307 // don't insert between attributes and an item
308 if item.attrs.is_empty() {
309 self.span = Some(item.span.shrink_to_lo());
311 // find the first attribute on the item
312 for attr in &item.attrs {
313 if self.span.map_or(true, |span| attr.span < span) {
314 self.span = Some(attr.span.shrink_to_lo());
325 /// An intermediate resolution result.
327 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
328 /// items are visible in their whole block, while `Res`es only from the place they are defined
331 enum LexicalScopeBinding<'a> {
332 Item(&'a NameBinding<'a>),
336 impl<'a> LexicalScopeBinding<'a> {
337 fn item(self) -> Option<&'a NameBinding<'a>> {
339 LexicalScopeBinding::Item(binding) => Some(binding),
344 fn res(self) -> Res {
346 LexicalScopeBinding::Item(binding) => binding.res(),
347 LexicalScopeBinding::Res(res) => res,
352 #[derive(Copy, Clone, Debug)]
353 enum ModuleOrUniformRoot<'a> {
357 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
358 CrateRootAndExternPrelude,
360 /// Virtual module that denotes resolution in extern prelude.
361 /// Used for paths starting with `::` on 2018 edition.
364 /// Virtual module that denotes resolution in current scope.
365 /// Used only for resolving single-segment imports. The reason it exists is that import paths
366 /// are always split into two parts, the first of which should be some kind of module.
370 impl ModuleOrUniformRoot<'_> {
371 fn same_def(lhs: Self, rhs: Self) -> bool {
373 (ModuleOrUniformRoot::Module(lhs),
374 ModuleOrUniformRoot::Module(rhs)) => lhs.def_id() == rhs.def_id(),
375 (ModuleOrUniformRoot::CrateRootAndExternPrelude,
376 ModuleOrUniformRoot::CrateRootAndExternPrelude) |
377 (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) |
378 (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
384 #[derive(Clone, Debug)]
385 enum PathResult<'a> {
386 Module(ModuleOrUniformRoot<'a>),
387 NonModule(PartialRes),
392 suggestion: Option<Suggestion>,
393 is_error_from_last_segment: bool,
398 /// An anonymous module; e.g., just a block.
403 /// { // This is an anonymous module
404 /// f(); // This resolves to (2) as we are inside the block.
407 /// f(); // Resolves to (1)
411 /// Any module with a name.
415 /// * A normal module ‒ either `mod from_file;` or `mod from_block { }`.
416 /// * A trait or an enum (it implicitly contains associated types, methods and variant
418 Def(DefKind, DefId, Name),
422 /// Get name of the module.
423 pub fn name(&self) -> Option<Name> {
425 ModuleKind::Block(..) => None,
426 ModuleKind::Def(.., name) => Some(*name),
431 /// A key that identifies a binding in a given `Module`.
433 /// Multiple bindings in the same module can have the same key (in a valid
434 /// program) if all but one of them come from glob imports.
435 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
437 /// The identifier for the binding, aways the `modern` version of the
441 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
442 /// `_` in the expanded AST that introduced this binding.
446 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
448 /// One node in the tree of modules.
449 pub struct ModuleData<'a> {
450 parent: Option<Module<'a>>,
453 // The def id of the closest normal module (`mod`) ancestor (including this module).
454 normal_ancestor_id: DefId,
456 // Mapping between names and their (possibly in-progress) resolutions in this module.
457 // Resolutions in modules from other crates are not populated until accessed.
458 lazy_resolutions: Resolutions<'a>,
459 // True if this is a module from other crate that needs to be populated on access.
460 populate_on_access: Cell<bool>,
462 // Macro invocations that can expand into items in this module.
463 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
465 no_implicit_prelude: bool,
467 glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
468 globs: RefCell<Vec<&'a ImportDirective<'a>>>,
470 // Used to memoize the traits in this module for faster searches through all traits in scope.
471 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
473 /// Span of the module itself. Used for error reporting.
479 type Module<'a> = &'a ModuleData<'a>;
481 impl<'a> ModuleData<'a> {
482 fn new(parent: Option<Module<'a>>,
484 normal_ancestor_id: DefId,
486 span: Span) -> Self {
491 lazy_resolutions: Default::default(),
492 populate_on_access: Cell::new(!normal_ancestor_id.is_local()),
493 unexpanded_invocations: Default::default(),
494 no_implicit_prelude: false,
495 glob_importers: RefCell::new(Vec::new()),
496 globs: RefCell::new(Vec::new()),
497 traits: RefCell::new(None),
503 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
504 where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
506 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
507 name_resolution.borrow().binding.map(|binding| f(resolver, key.ident, key.ns, binding));
511 fn res(&self) -> Option<Res> {
513 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
518 fn def_id(&self) -> Option<DefId> {
520 ModuleKind::Def(_, def_id, _) => Some(def_id),
525 // `self` resolves to the first module ancestor that `is_normal`.
526 fn is_normal(&self) -> bool {
528 ModuleKind::Def(DefKind::Mod, _, _) => true,
533 fn is_trait(&self) -> bool {
535 ModuleKind::Def(DefKind::Trait, _, _) => true,
540 fn nearest_item_scope(&'a self) -> Module<'a> {
542 ModuleKind::Def(DefKind::Enum, ..) | ModuleKind::Def(DefKind::Trait, ..) =>
543 self.parent.expect("enum or trait module without a parent"),
548 fn is_ancestor_of(&self, mut other: &Self) -> bool {
549 while !ptr::eq(self, other) {
550 if let Some(parent) = other.parent {
560 impl<'a> fmt::Debug for ModuleData<'a> {
561 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
562 write!(f, "{:?}", self.res())
566 /// Records a possibly-private value, type, or module definition.
567 #[derive(Clone, Debug)]
568 pub struct NameBinding<'a> {
569 kind: NameBindingKind<'a>,
570 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
576 pub trait ToNameBinding<'a> {
577 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
580 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
581 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
586 #[derive(Clone, Debug)]
587 enum NameBindingKind<'a> {
588 Res(Res, /* is_macro_export */ bool),
591 binding: &'a NameBinding<'a>,
592 directive: &'a ImportDirective<'a>,
597 impl<'a> NameBindingKind<'a> {
598 /// Is this a name binding of a import?
599 fn is_import(&self) -> bool {
601 NameBindingKind::Import { .. } => true,
607 struct PrivacyError<'a>(Span, Ident, &'a NameBinding<'a>);
609 struct UseError<'a> {
610 err: DiagnosticBuilder<'a>,
611 /// Attach `use` statements for these candidates.
612 candidates: Vec<ImportSuggestion>,
613 /// The `NodeId` of the module to place the use-statements in.
615 /// Whether the diagnostic should state that it's "better".
619 #[derive(Clone, Copy, PartialEq, Debug)]
632 fn descr(self) -> &'static str {
634 AmbiguityKind::Import =>
635 "name vs any other name during import resolution",
636 AmbiguityKind::BuiltinAttr =>
637 "built-in attribute vs any other name",
638 AmbiguityKind::DeriveHelper =>
639 "derive helper attribute vs any other name",
640 AmbiguityKind::LegacyVsModern =>
641 "`macro_rules` vs non-`macro_rules` from other module",
642 AmbiguityKind::GlobVsOuter =>
643 "glob import vs any other name from outer scope during import/macro resolution",
644 AmbiguityKind::GlobVsGlob =>
645 "glob import vs glob import in the same module",
646 AmbiguityKind::GlobVsExpanded =>
647 "glob import vs macro-expanded name in the same \
648 module during import/macro resolution",
649 AmbiguityKind::MoreExpandedVsOuter =>
650 "macro-expanded name vs less macro-expanded name \
651 from outer scope during import/macro resolution",
656 /// Miscellaneous bits of metadata for better ambiguity error reporting.
657 #[derive(Clone, Copy, PartialEq)]
658 enum AmbiguityErrorMisc {
665 struct AmbiguityError<'a> {
668 b1: &'a NameBinding<'a>,
669 b2: &'a NameBinding<'a>,
670 misc1: AmbiguityErrorMisc,
671 misc2: AmbiguityErrorMisc,
674 impl<'a> NameBinding<'a> {
675 fn module(&self) -> Option<Module<'a>> {
677 NameBindingKind::Module(module) => Some(module),
678 NameBindingKind::Import { binding, .. } => binding.module(),
683 fn res(&self) -> Res {
685 NameBindingKind::Res(res, _) => res,
686 NameBindingKind::Module(module) => module.res().unwrap(),
687 NameBindingKind::Import { binding, .. } => binding.res(),
691 fn is_ambiguity(&self) -> bool {
692 self.ambiguity.is_some() || match self.kind {
693 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
698 // We sometimes need to treat variants as `pub` for backwards compatibility.
699 fn pseudo_vis(&self) -> ty::Visibility {
700 if self.is_variant() && self.res().def_id().is_local() {
701 ty::Visibility::Public
707 fn is_variant(&self) -> bool {
709 NameBindingKind::Res(Res::Def(DefKind::Variant, _), _) |
710 NameBindingKind::Res(Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _), _) => true,
715 fn is_extern_crate(&self) -> bool {
717 NameBindingKind::Import {
718 directive: &ImportDirective {
719 subclass: ImportDirectiveSubclass::ExternCrate { .. }, ..
722 NameBindingKind::Module(
723 &ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }
724 ) => def_id.index == CRATE_DEF_INDEX,
729 fn is_import(&self) -> bool {
731 NameBindingKind::Import { .. } => true,
736 fn is_glob_import(&self) -> bool {
738 NameBindingKind::Import { directive, .. } => directive.is_glob(),
743 fn is_importable(&self) -> bool {
745 Res::Def(DefKind::AssocConst, _)
746 | Res::Def(DefKind::Method, _)
747 | Res::Def(DefKind::AssocTy, _) => false,
752 fn is_macro_def(&self) -> bool {
754 NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
759 fn macro_kind(&self) -> Option<MacroKind> {
760 self.res().macro_kind()
763 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
764 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
765 // Then this function returns `true` if `self` may emerge from a macro *after* that
766 // in some later round and screw up our previously found resolution.
767 // See more detailed explanation in
768 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
769 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
770 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
771 // Expansions are partially ordered, so "may appear after" is an inversion of
772 // "certainly appears before or simultaneously" and includes unordered cases.
773 let self_parent_expansion = self.expansion;
774 let other_parent_expansion = binding.expansion;
775 let certainly_before_other_or_simultaneously =
776 other_parent_expansion.is_descendant_of(self_parent_expansion);
777 let certainly_before_invoc_or_simultaneously =
778 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
779 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
783 /// Interns the names of the primitive types.
785 /// All other types are defined somewhere and possibly imported, but the primitive ones need
786 /// special handling, since they have no place of origin.
787 struct PrimitiveTypeTable {
788 primitive_types: FxHashMap<Name, PrimTy>,
791 impl PrimitiveTypeTable {
792 fn new() -> PrimitiveTypeTable {
793 let mut table = FxHashMap::default();
795 table.insert(sym::bool, Bool);
796 table.insert(sym::char, Char);
797 table.insert(sym::f32, Float(FloatTy::F32));
798 table.insert(sym::f64, Float(FloatTy::F64));
799 table.insert(sym::isize, Int(IntTy::Isize));
800 table.insert(sym::i8, Int(IntTy::I8));
801 table.insert(sym::i16, Int(IntTy::I16));
802 table.insert(sym::i32, Int(IntTy::I32));
803 table.insert(sym::i64, Int(IntTy::I64));
804 table.insert(sym::i128, Int(IntTy::I128));
805 table.insert(sym::str, Str);
806 table.insert(sym::usize, Uint(UintTy::Usize));
807 table.insert(sym::u8, Uint(UintTy::U8));
808 table.insert(sym::u16, Uint(UintTy::U16));
809 table.insert(sym::u32, Uint(UintTy::U32));
810 table.insert(sym::u64, Uint(UintTy::U64));
811 table.insert(sym::u128, Uint(UintTy::U128));
812 Self { primitive_types: table }
816 #[derive(Debug, Default, Clone)]
817 pub struct ExternPreludeEntry<'a> {
818 extern_crate_item: Option<&'a NameBinding<'a>>,
819 pub introduced_by_item: bool,
822 /// The main resolver class.
824 /// This is the visitor that walks the whole crate.
825 pub struct Resolver<'a> {
826 session: &'a Session,
828 definitions: Definitions,
830 graph_root: Module<'a>,
832 prelude: Option<Module<'a>>,
833 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
835 /// N.B., this is used only for better diagnostics, not name resolution itself.
836 has_self: FxHashSet<DefId>,
838 /// Names of fields of an item `DefId` accessible with dot syntax.
839 /// Used for hints during error reporting.
840 field_names: FxHashMap<DefId, Vec<Spanned<Name>>>,
842 /// All imports known to succeed or fail.
843 determined_imports: Vec<&'a ImportDirective<'a>>,
845 /// All non-determined imports.
846 indeterminate_imports: Vec<&'a ImportDirective<'a>>,
848 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
849 /// We are resolving a last import segment during import validation.
850 last_import_segment: bool,
851 /// This binding should be ignored during in-module resolution, so that we don't get
852 /// "self-confirming" import resolutions during import validation.
853 blacklisted_binding: Option<&'a NameBinding<'a>>,
855 /// The idents for the primitive types.
856 primitive_type_table: PrimitiveTypeTable,
858 /// Resolutions for nodes that have a single resolution.
859 partial_res_map: NodeMap<PartialRes>,
860 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
861 import_res_map: NodeMap<PerNS<Option<Res>>>,
862 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
863 label_res_map: NodeMap<NodeId>,
865 /// `CrateNum` resolutions of `extern crate` items.
866 extern_crate_map: NodeMap<CrateNum>,
867 export_map: ExportMap<NodeId>,
870 /// A map from nodes to anonymous modules.
871 /// Anonymous modules are pseudo-modules that are implicitly created around items
872 /// contained within blocks.
874 /// For example, if we have this:
882 /// There will be an anonymous module created around `g` with the ID of the
883 /// entry block for `f`.
884 block_map: NodeMap<Module<'a>>,
885 /// A fake module that contains no definition and no prelude. Used so that
886 /// some AST passes can generate identifiers that only resolve to local or
888 empty_module: Module<'a>,
889 module_map: FxHashMap<DefId, Module<'a>>,
890 extern_module_map: FxHashMap<DefId, Module<'a>>,
891 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
892 underscore_disambiguator: u32,
894 /// Maps glob imports to the names of items actually imported.
897 used_imports: FxHashSet<(NodeId, Namespace)>,
898 maybe_unused_trait_imports: NodeSet,
899 maybe_unused_extern_crates: Vec<(NodeId, Span)>,
901 /// Privacy errors are delayed until the end in order to deduplicate them.
902 privacy_errors: Vec<PrivacyError<'a>>,
903 /// Ambiguity errors are delayed for deduplication.
904 ambiguity_errors: Vec<AmbiguityError<'a>>,
905 /// `use` injections are delayed for better placement and deduplication.
906 use_injections: Vec<UseError<'a>>,
907 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
908 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
910 arenas: &'a ResolverArenas<'a>,
911 dummy_binding: &'a NameBinding<'a>,
913 crate_loader: CrateLoader<'a>,
914 macro_names: FxHashSet<Ident>,
915 builtin_macros: FxHashMap<Name, SyntaxExtension>,
916 registered_attrs: FxHashSet<Ident>,
917 registered_tools: FxHashSet<Ident>,
918 macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
919 all_macros: FxHashMap<Name, Res>,
920 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
921 dummy_ext_bang: Lrc<SyntaxExtension>,
922 dummy_ext_derive: Lrc<SyntaxExtension>,
923 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
924 macro_defs: FxHashMap<ExpnId, DefId>,
925 local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
926 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
927 unused_macros: NodeMap<Span>,
928 proc_macro_stubs: NodeSet,
929 /// Traces collected during macro resolution and validated when it's complete.
930 single_segment_macro_resolutions: Vec<(Ident, MacroKind, ParentScope<'a>,
931 Option<&'a NameBinding<'a>>)>,
932 multi_segment_macro_resolutions: Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>,
934 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
935 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
936 /// Derive macros cannot modify the item themselves and have to store the markers in the global
937 /// context, so they attach the markers to derive container IDs using this resolver table.
938 containers_deriving_copy: FxHashSet<ExpnId>,
939 /// Parent scopes in which the macros were invoked.
940 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
941 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
942 /// Legacy scopes *produced* by expanding the macro invocations,
943 /// include all the `macro_rules` items and other invocations generated by them.
944 output_legacy_scopes: FxHashMap<ExpnId, LegacyScope<'a>>,
946 /// Avoid duplicated errors for "name already defined".
947 name_already_seen: FxHashMap<Name, Span>,
949 potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
951 /// Table for mapping struct IDs into struct constructor IDs,
952 /// it's not used during normal resolution, only for better error reporting.
953 struct_constructors: DefIdMap<(Res, ty::Visibility)>,
955 /// Features enabled for this crate.
956 active_features: FxHashSet<Name>,
958 /// Stores enum visibilities to properly build a reduced graph
959 /// when visiting the correspondent variants.
960 variant_vis: DefIdMap<ty::Visibility>,
962 lint_buffer: lint::LintBuffer,
964 next_node_id: NodeId,
967 /// Nothing really interesting here; it just provides memory for the rest of the crate.
969 pub struct ResolverArenas<'a> {
970 modules: arena::TypedArena<ModuleData<'a>>,
971 local_modules: RefCell<Vec<Module<'a>>>,
972 name_bindings: arena::TypedArena<NameBinding<'a>>,
973 import_directives: arena::TypedArena<ImportDirective<'a>>,
974 name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
975 legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
976 ast_paths: arena::TypedArena<ast::Path>,
979 impl<'a> ResolverArenas<'a> {
980 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
981 let module = self.modules.alloc(module);
982 if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
983 self.local_modules.borrow_mut().push(module);
987 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
988 self.local_modules.borrow()
990 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
991 self.name_bindings.alloc(name_binding)
993 fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
994 -> &'a ImportDirective<'_> {
995 self.import_directives.alloc(import_directive)
997 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
998 self.name_resolutions.alloc(Default::default())
1000 fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1001 self.legacy_bindings.alloc(binding)
1003 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1004 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1008 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1009 fn as_mut(&mut self) -> &mut Resolver<'a> { self }
1012 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1013 fn parent(self, id: DefId) -> Option<DefId> {
1015 LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1016 _ => self.cstore().def_key(id).parent,
1017 }.map(|index| DefId { index, ..id })
1021 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1022 /// the resolver is no longer needed as all the relevant information is inline.
1023 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1024 fn cstore(&self) -> &dyn CrateStore {
1028 fn resolve_str_path(
1031 crate_root: Option<Name>,
1032 components: &[Name],
1034 ) -> (ast::Path, Res) {
1035 let root = if crate_root.is_some() {
1040 let segments = iter::once(Ident::with_dummy_span(root))
1042 crate_root.into_iter()
1043 .chain(components.iter().cloned())
1044 .map(Ident::with_dummy_span)
1045 ).map(|i| self.new_ast_path_segment(i)).collect::<Vec<_>>();
1047 let path = ast::Path {
1052 let parent_scope = &ParentScope::module(self.graph_root);
1053 let res = match self.resolve_ast_path(&path, ns, parent_scope) {
1055 Err((span, error)) => {
1056 self.report_error(span, error);
1063 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1064 self.partial_res_map.get(&id).cloned()
1067 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1068 self.import_res_map.get(&id).cloned().unwrap_or_default()
1071 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1072 self.label_res_map.get(&id).cloned()
1075 fn definitions(&mut self) -> &mut Definitions {
1076 &mut self.definitions
1079 fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1080 &mut self.lint_buffer
1083 fn next_node_id(&mut self) -> NodeId {
1088 impl<'a> Resolver<'a> {
1089 pub fn new(session: &'a Session,
1092 metadata_loader: &'a MetadataLoaderDyn,
1093 arenas: &'a ResolverArenas<'a>)
1095 let root_def_id = DefId::local(CRATE_DEF_INDEX);
1096 let root_module_kind = ModuleKind::Def(
1101 let graph_root = arenas.alloc_module(ModuleData {
1102 no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
1103 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1105 let empty_module_kind = ModuleKind::Def(
1110 let empty_module = arenas.alloc_module(ModuleData {
1111 no_implicit_prelude: true,
1120 let mut module_map = FxHashMap::default();
1121 module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1123 let mut definitions = Definitions::default();
1124 definitions.create_root_def(crate_name, session.local_crate_disambiguator());
1126 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> =
1127 session.opts.externs.iter().map(|kv| (Ident::from_str(kv.0), Default::default()))
1130 if !attr::contains_name(&krate.attrs, sym::no_core) {
1131 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1132 if !attr::contains_name(&krate.attrs, sym::no_std) {
1133 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1134 if session.rust_2018() {
1135 extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default());
1140 let (registered_attrs, registered_tools) =
1141 macros::registered_attrs_and_tools(session, &krate.attrs);
1143 let mut invocation_parent_scopes = FxHashMap::default();
1144 invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root));
1146 let mut macro_defs = FxHashMap::default();
1147 macro_defs.insert(ExpnId::root(), root_def_id);
1149 let features = session.features_untracked();
1150 let non_macro_attr =
1151 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1158 // The outermost module has def ID 0; this is not reflected in the
1164 has_self: FxHashSet::default(),
1165 field_names: FxHashMap::default(),
1167 determined_imports: Vec::new(),
1168 indeterminate_imports: Vec::new(),
1170 last_import_segment: false,
1171 blacklisted_binding: None,
1173 primitive_type_table: PrimitiveTypeTable::new(),
1175 partial_res_map: Default::default(),
1176 import_res_map: Default::default(),
1177 label_res_map: Default::default(),
1178 extern_crate_map: Default::default(),
1179 export_map: FxHashMap::default(),
1180 trait_map: Default::default(),
1181 underscore_disambiguator: 0,
1184 block_map: Default::default(),
1185 extern_module_map: FxHashMap::default(),
1186 binding_parent_modules: FxHashMap::default(),
1187 ast_transform_scopes: FxHashMap::default(),
1189 glob_map: Default::default(),
1191 used_imports: FxHashSet::default(),
1192 maybe_unused_trait_imports: Default::default(),
1193 maybe_unused_extern_crates: Vec::new(),
1195 privacy_errors: Vec::new(),
1196 ambiguity_errors: Vec::new(),
1197 use_injections: Vec::new(),
1198 macro_expanded_macro_export_errors: BTreeSet::new(),
1201 dummy_binding: arenas.alloc_name_binding(NameBinding {
1202 kind: NameBindingKind::Res(Res::Err, false),
1204 expansion: ExpnId::root(),
1206 vis: ty::Visibility::Public,
1209 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1210 macro_names: FxHashSet::default(),
1211 builtin_macros: Default::default(),
1214 macro_use_prelude: FxHashMap::default(),
1215 all_macros: FxHashMap::default(),
1216 macro_map: FxHashMap::default(),
1217 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1218 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1219 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1220 invocation_parent_scopes,
1221 output_legacy_scopes: Default::default(),
1223 local_macro_def_scopes: FxHashMap::default(),
1224 name_already_seen: FxHashMap::default(),
1225 potentially_unused_imports: Vec::new(),
1226 struct_constructors: Default::default(),
1227 unused_macros: Default::default(),
1228 proc_macro_stubs: Default::default(),
1229 single_segment_macro_resolutions: Default::default(),
1230 multi_segment_macro_resolutions: Default::default(),
1231 builtin_attrs: Default::default(),
1232 containers_deriving_copy: Default::default(),
1234 features.declared_lib_features.iter().map(|(feat, ..)| *feat)
1235 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1237 variant_vis: Default::default(),
1238 lint_buffer: lint::LintBuffer::default(),
1239 next_node_id: NodeId::from_u32(1),
1243 pub fn next_node_id(&mut self) -> NodeId {
1244 let next = self.next_node_id.as_usize()
1246 .expect("input too large; ran out of NodeIds");
1247 self.next_node_id = ast::NodeId::from_usize(next);
1251 pub fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1252 &mut self.lint_buffer
1255 pub fn arenas() -> ResolverArenas<'a> {
1259 pub fn into_outputs(self) -> ResolverOutputs {
1261 definitions: self.definitions,
1262 cstore: Box::new(self.crate_loader.into_cstore()),
1263 extern_crate_map: self.extern_crate_map,
1264 export_map: self.export_map,
1265 trait_map: self.trait_map,
1266 glob_map: self.glob_map,
1267 maybe_unused_trait_imports: self.maybe_unused_trait_imports,
1268 maybe_unused_extern_crates: self.maybe_unused_extern_crates,
1269 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1270 (ident.name, entry.introduced_by_item)
1275 pub fn clone_outputs(&self) -> ResolverOutputs {
1277 definitions: self.definitions.clone(),
1278 cstore: Box::new(self.cstore().clone()),
1279 extern_crate_map: self.extern_crate_map.clone(),
1280 export_map: self.export_map.clone(),
1281 trait_map: self.trait_map.clone(),
1282 glob_map: self.glob_map.clone(),
1283 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1284 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1285 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1286 (ident.name, entry.introduced_by_item)
1291 pub fn cstore(&self) -> &CStore {
1292 self.crate_loader.cstore()
1295 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1296 self.non_macro_attrs[mark_used as usize].clone()
1299 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1301 MacroKind::Bang => self.dummy_ext_bang.clone(),
1302 MacroKind::Derive => self.dummy_ext_derive.clone(),
1303 MacroKind::Attr => self.non_macro_attr(true),
1307 /// Runs the function on each namespace.
1308 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1314 fn is_builtin_macro(&mut self, res: Res) -> bool {
1315 self.get_macro(res).map_or(false, |ext| ext.is_builtin)
1318 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1320 match self.macro_defs.get(&ctxt.outer_expn()) {
1321 Some(&def_id) => return def_id,
1322 None => ctxt.remove_mark(),
1327 /// Entry point to crate resolution.
1328 pub fn resolve_crate(&mut self, krate: &Crate) {
1330 self.session.prof.generic_activity("resolve_crate");
1332 ImportResolver { r: self }.finalize_imports();
1333 self.finalize_macro_resolutions();
1335 self.late_resolve_crate(krate);
1337 self.check_unused(krate);
1338 self.report_errors(krate);
1339 self.crate_loader.postprocess(krate);
1346 normal_ancestor_id: DefId,
1350 let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span);
1351 self.arenas.alloc_module(module)
1354 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1355 let ident = ident.modern();
1356 let disambiguator = if ident.name == kw::Underscore {
1357 self.underscore_disambiguator += 1;
1358 self.underscore_disambiguator
1362 BindingKey { ident, ns, disambiguator }
1365 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1366 if module.populate_on_access.get() {
1367 module.populate_on_access.set(false);
1368 self.build_reduced_graph_external(module);
1370 &module.lazy_resolutions
1373 fn resolution(&mut self, module: Module<'a>, key: BindingKey)
1374 -> &'a RefCell<NameResolution<'a>> {
1375 *self.resolutions(module).borrow_mut().entry(key)
1376 .or_insert_with(|| self.arenas.alloc_name_resolution())
1379 fn record_use(&mut self, ident: Ident, ns: Namespace,
1380 used_binding: &'a NameBinding<'a>, is_lexical_scope: bool) {
1381 if let Some((b2, kind)) = used_binding.ambiguity {
1382 self.ambiguity_errors.push(AmbiguityError {
1383 kind, ident, b1: used_binding, b2,
1384 misc1: AmbiguityErrorMisc::None,
1385 misc2: AmbiguityErrorMisc::None,
1388 if let NameBindingKind::Import { directive, binding, ref used } = used_binding.kind {
1389 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1390 // but not introduce it, as used if they are accessed from lexical scope.
1391 if is_lexical_scope {
1392 if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
1393 if let Some(crate_item) = entry.extern_crate_item {
1394 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1401 directive.used.set(true);
1402 self.used_imports.insert((directive.id, ns));
1403 self.add_to_glob_map(&directive, ident);
1404 self.record_use(ident, ns, binding, false);
1409 fn add_to_glob_map(&mut self, directive: &ImportDirective<'_>, ident: Ident) {
1410 if directive.is_glob() {
1411 self.glob_map.entry(directive.id).or_default().insert(ident.name);
1415 /// A generic scope visitor.
1416 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1417 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1420 scope_set: ScopeSet,
1421 parent_scope: &ParentScope<'a>,
1423 mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>,
1425 // General principles:
1426 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1427 // built into the language or standard library. This way we can add new names into the
1428 // language or standard library without breaking user code.
1429 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1430 // Places to search (in order of decreasing priority):
1432 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1433 // (open set, not controlled).
1434 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1435 // (open, not controlled).
1436 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1437 // 4. Tool modules (closed, controlled right now, but not in the future).
1438 // 5. Standard library prelude (de-facto closed, controlled).
1439 // 6. Language prelude (closed, controlled).
1441 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1442 // (open set, not controlled).
1443 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1444 // (open, not controlled).
1445 // 3. Standard library prelude (de-facto closed, controlled).
1447 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1448 // are currently reported as errors. They should be higher in priority than preludes
1449 // and probably even names in modules according to the "general principles" above. They
1450 // also should be subject to restricted shadowing because are effectively produced by
1451 // derives (you need to resolve the derive first to add helpers into scope), but they
1452 // should be available before the derive is expanded for compatibility.
1453 // It's mess in general, so we are being conservative for now.
1454 // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
1455 // priority than prelude macros, but create ambiguities with macros in modules.
1456 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1457 // (open, not controlled). Have higher priority than prelude macros, but create
1458 // ambiguities with `macro_rules`.
1459 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1460 // 4a. User-defined prelude from macro-use
1461 // (open, the open part is from macro expansions, not controlled).
1462 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1463 // 4c. Standard library prelude (de-facto closed, controlled).
1464 // 6. Language prelude: builtin attributes (closed, controlled).
1465 // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
1466 // but introduced by legacy plugins using `register_attribute`. Priority is somewhere
1467 // in prelude, not sure where exactly (creates ambiguities with any other prelude names).
1469 let rust_2015 = ident.span.rust_2015();
1470 let (ns, is_absolute_path) = match scope_set {
1471 ScopeSet::All(ns, _) => (ns, false),
1472 ScopeSet::AbsolutePath(ns) => (ns, true),
1473 ScopeSet::Macro(_) => (MacroNS, false),
1475 // Jump out of trait or enum modules, they do not act as scopes.
1476 let module = parent_scope.module.nearest_item_scope();
1477 let mut scope = match ns {
1478 _ if is_absolute_path => Scope::CrateRoot,
1479 TypeNS | ValueNS => Scope::Module(module),
1480 MacroNS => Scope::DeriveHelpersCompat,
1482 let mut ident = ident.modern();
1483 let mut use_prelude = !module.no_implicit_prelude;
1486 let visit = match scope {
1487 Scope::DeriveHelpersCompat => true,
1488 Scope::MacroRules(..) => true,
1489 Scope::CrateRoot => true,
1490 Scope::Module(..) => true,
1491 Scope::RegisteredAttrs => use_prelude,
1492 Scope::MacroUsePrelude => use_prelude || rust_2015,
1493 Scope::BuiltinAttrs => true,
1494 Scope::LegacyPluginHelpers => use_prelude || rust_2015,
1495 Scope::ExternPrelude => use_prelude || is_absolute_path,
1496 Scope::ToolPrelude => use_prelude,
1497 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1498 Scope::BuiltinTypes => true,
1502 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) {
1503 return break_result;
1507 scope = match scope {
1508 Scope::DeriveHelpersCompat =>
1509 Scope::MacroRules(parent_scope.legacy),
1510 Scope::MacroRules(legacy_scope) => match legacy_scope {
1511 LegacyScope::Binding(binding) => Scope::MacroRules(
1512 binding.parent_legacy_scope
1514 LegacyScope::Invocation(invoc_id) => Scope::MacroRules(
1515 self.output_legacy_scopes.get(&invoc_id).cloned()
1516 .unwrap_or(self.invocation_parent_scopes[&invoc_id].legacy)
1518 LegacyScope::Empty => Scope::Module(module),
1520 Scope::CrateRoot => match ns {
1522 ident.span.adjust(ExpnId::root());
1523 Scope::ExternPrelude
1525 ValueNS | MacroNS => break,
1527 Scope::Module(module) => {
1528 use_prelude = !module.no_implicit_prelude;
1529 match self.hygienic_lexical_parent(module, &mut ident.span) {
1530 Some(parent_module) => Scope::Module(parent_module),
1532 ident.span.adjust(ExpnId::root());
1534 TypeNS => Scope::ExternPrelude,
1535 ValueNS => Scope::StdLibPrelude,
1536 MacroNS => Scope::RegisteredAttrs,
1541 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1542 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1543 Scope::BuiltinAttrs => Scope::LegacyPluginHelpers,
1544 Scope::LegacyPluginHelpers => break, // nowhere else to search
1545 Scope::ExternPrelude if is_absolute_path => break,
1546 Scope::ExternPrelude => Scope::ToolPrelude,
1547 Scope::ToolPrelude => Scope::StdLibPrelude,
1548 Scope::StdLibPrelude => match ns {
1549 TypeNS => Scope::BuiltinTypes,
1550 ValueNS => break, // nowhere else to search
1551 MacroNS => Scope::BuiltinAttrs,
1553 Scope::BuiltinTypes => break, // nowhere else to search
1560 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1561 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1562 /// `ident` in the first scope that defines it (or None if no scopes define it).
1564 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1565 /// the items are defined in the block. For example,
1568 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1571 /// g(); // This resolves to the local variable `g` since it shadows the item.
1575 /// Invariant: This must only be called during main resolution, not during
1576 /// import resolution.
1577 fn resolve_ident_in_lexical_scope(&mut self,
1580 parent_scope: &ParentScope<'a>,
1581 record_used_id: Option<NodeId>,
1584 -> Option<LexicalScopeBinding<'a>> {
1585 assert!(ns == TypeNS || ns == ValueNS);
1586 if ident.name == kw::Invalid {
1587 return Some(LexicalScopeBinding::Res(Res::Err));
1589 let (general_span, modern_span) = if ident.name == kw::SelfUpper {
1590 // FIXME(jseyfried) improve `Self` hygiene
1591 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1592 (empty_span, empty_span)
1593 } else if ns == TypeNS {
1594 let modern_span = ident.span.modern();
1595 (modern_span, modern_span)
1597 (ident.span.modern_and_legacy(), ident.span.modern())
1599 ident.span = general_span;
1600 let modern_ident = Ident { span: modern_span, ..ident };
1602 // Walk backwards up the ribs in scope.
1603 let record_used = record_used_id.is_some();
1604 let mut module = self.graph_root;
1605 for i in (0 .. ribs.len()).rev() {
1606 debug!("walk rib\n{:?}", ribs[i].bindings);
1607 // Use the rib kind to determine whether we are resolving parameters
1608 // (modern hygiene) or local variables (legacy hygiene).
1609 let rib_ident = if ribs[i].kind.contains_params() {
1614 if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() {
1615 // The ident resolves to a type parameter or local variable.
1616 return Some(LexicalScopeBinding::Res(
1617 self.validate_res_from_ribs(i, rib_ident, res, record_used, path_span, ribs),
1621 module = match ribs[i].kind {
1622 ModuleRibKind(module) => module,
1623 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1624 // If an invocation of this macro created `ident`, give up on `ident`
1625 // and switch to `ident`'s source from the macro definition.
1626 ident.span.remove_mark();
1633 let item = self.resolve_ident_in_module_unadjusted(
1634 ModuleOrUniformRoot::Module(module),
1641 if let Ok(binding) = item {
1642 // The ident resolves to an item.
1643 return Some(LexicalScopeBinding::Item(binding));
1647 ModuleKind::Block(..) => {}, // We can see through blocks
1652 ident = modern_ident;
1653 let mut poisoned = None;
1655 let opt_module = if let Some(node_id) = record_used_id {
1656 self.hygienic_lexical_parent_with_compatibility_fallback(module, &mut ident.span,
1657 node_id, &mut poisoned)
1659 self.hygienic_lexical_parent(module, &mut ident.span)
1661 module = unwrap_or!(opt_module, break);
1662 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1663 let result = self.resolve_ident_in_module_unadjusted(
1664 ModuleOrUniformRoot::Module(module),
1667 adjusted_parent_scope,
1674 if let Some(node_id) = poisoned {
1675 self.lint_buffer.buffer_lint_with_diagnostic(
1676 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1677 node_id, ident.span,
1678 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1679 lint::builtin::BuiltinLintDiagnostics::
1680 ProcMacroDeriveResolutionFallback(ident.span),
1683 return Some(LexicalScopeBinding::Item(binding))
1685 Err(Determined) => continue,
1686 Err(Undetermined) =>
1687 span_bug!(ident.span, "undetermined resolution during main resolution pass"),
1691 if !module.no_implicit_prelude {
1692 ident.span.adjust(ExpnId::root());
1694 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1695 return Some(LexicalScopeBinding::Item(binding));
1697 if let Some(ident) = self.registered_tools.get(&ident) {
1698 let binding = (Res::ToolMod, ty::Visibility::Public,
1699 ident.span, ExpnId::root()).to_name_binding(self.arenas);
1700 return Some(LexicalScopeBinding::Item(binding));
1703 if let Some(prelude) = self.prelude {
1704 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1705 ModuleOrUniformRoot::Module(prelude),
1712 return Some(LexicalScopeBinding::Item(binding));
1720 fn hygienic_lexical_parent(&mut self, module: Module<'a>, span: &mut Span)
1721 -> Option<Module<'a>> {
1722 if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1723 return Some(self.macro_def_scope(span.remove_mark()));
1726 if let ModuleKind::Block(..) = module.kind {
1727 return Some(module.parent.unwrap().nearest_item_scope());
1733 fn hygienic_lexical_parent_with_compatibility_fallback(&mut self, module: Module<'a>,
1734 span: &mut Span, node_id: NodeId,
1735 poisoned: &mut Option<NodeId>)
1736 -> Option<Module<'a>> {
1737 if let module @ Some(..) = self.hygienic_lexical_parent(module, span) {
1741 // We need to support the next case under a deprecation warning
1744 // ---- begin: this comes from a proc macro derive
1745 // mod implementation_details {
1746 // // Note that `MyStruct` is not in scope here.
1747 // impl SomeTrait for MyStruct { ... }
1751 // So we have to fall back to the module's parent during lexical resolution in this case.
1752 if let Some(parent) = module.parent {
1753 // Inner module is inside the macro, parent module is outside of the macro.
1754 if module.expansion != parent.expansion &&
1755 module.expansion.is_descendant_of(parent.expansion) {
1756 // The macro is a proc macro derive
1757 if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
1758 if let Some(ext) = self.get_macro_by_def_id(def_id) {
1759 if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
1760 if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1761 *poisoned = Some(node_id);
1762 return module.parent;
1773 fn resolve_ident_in_module(
1775 module: ModuleOrUniformRoot<'a>,
1778 parent_scope: &ParentScope<'a>,
1781 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1782 self.resolve_ident_in_module_ext(
1783 module, ident, ns, parent_scope, record_used, path_span
1784 ).map_err(|(determinacy, _)| determinacy)
1787 fn resolve_ident_in_module_ext(
1789 module: ModuleOrUniformRoot<'a>,
1792 parent_scope: &ParentScope<'a>,
1795 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
1796 let tmp_parent_scope;
1797 let mut adjusted_parent_scope = parent_scope;
1799 ModuleOrUniformRoot::Module(m) => {
1800 if let Some(def) = ident.span.modernize_and_adjust(m.expansion) {
1802 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
1803 adjusted_parent_scope = &tmp_parent_scope;
1806 ModuleOrUniformRoot::ExternPrelude => {
1807 ident.span.modernize_and_adjust(ExpnId::root());
1809 ModuleOrUniformRoot::CrateRootAndExternPrelude |
1810 ModuleOrUniformRoot::CurrentScope => {
1814 let result = self.resolve_ident_in_module_unadjusted_ext(
1815 module, ident, ns, adjusted_parent_scope, false, record_used, path_span,
1820 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
1821 let mut ctxt = ident.span.ctxt();
1822 let mark = if ident.name == kw::DollarCrate {
1823 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
1824 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
1825 // as described in `SyntaxContext::apply_mark`, so we ignore prepended modern marks.
1826 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
1827 // definitions actually produced by `macro` and `macro` definitions produced by
1828 // `macro_rules!`, but at least such configurations are not stable yet.
1829 ctxt = ctxt.modern_and_legacy();
1830 let mut iter = ctxt.marks().into_iter().rev().peekable();
1831 let mut result = None;
1832 // Find the last modern mark from the end if it exists.
1833 while let Some(&(mark, transparency)) = iter.peek() {
1834 if transparency == Transparency::Opaque {
1835 result = Some(mark);
1841 // Then find the last legacy mark from the end if it exists.
1842 for (mark, transparency) in iter {
1843 if transparency == Transparency::SemiTransparent {
1844 result = Some(mark);
1851 ctxt = ctxt.modern();
1852 ctxt.adjust(ExpnId::root())
1854 let module = match mark {
1855 Some(def) => self.macro_def_scope(def),
1856 None => return self.graph_root,
1858 self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
1861 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
1862 let mut module = self.get_module(module.normal_ancestor_id);
1863 while module.span.ctxt().modern() != *ctxt {
1864 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
1865 module = self.get_module(parent.normal_ancestor_id);
1873 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1874 parent_scope: &ParentScope<'a>,
1877 crate_lint: CrateLint,
1878 ) -> PathResult<'a> {
1879 self.resolve_path_with_ribs(
1880 path, opt_ns, parent_scope, record_used, path_span, crate_lint, None
1884 fn resolve_path_with_ribs(
1887 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1888 parent_scope: &ParentScope<'a>,
1891 crate_lint: CrateLint,
1892 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
1893 ) -> PathResult<'a> {
1894 let mut module = None;
1895 let mut allow_super = true;
1896 let mut second_binding = None;
1899 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
1900 path_span={:?}, crate_lint={:?})",
1908 for (i, &Segment { ident, id }) in path.iter().enumerate() {
1909 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
1910 let record_segment_res = |this: &mut Self, res| {
1912 if let Some(id) = id {
1913 if !this.partial_res_map.contains_key(&id) {
1914 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
1915 this.record_partial_res(id, PartialRes::new(res));
1921 let is_last = i == path.len() - 1;
1922 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
1923 let name = ident.name;
1925 allow_super &= ns == TypeNS &&
1926 (name == kw::SelfLower ||
1930 if allow_super && name == kw::Super {
1931 let mut ctxt = ident.span.ctxt().modern();
1932 let self_module = match i {
1933 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
1935 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
1939 if let Some(self_module) = self_module {
1940 if let Some(parent) = self_module.parent {
1941 module = Some(ModuleOrUniformRoot::Module(
1942 self.resolve_self(&mut ctxt, parent)));
1946 let msg = "there are too many initial `super`s.".to_string();
1947 return PathResult::Failed {
1951 is_error_from_last_segment: false,
1955 if name == kw::SelfLower {
1956 let mut ctxt = ident.span.ctxt().modern();
1957 module = Some(ModuleOrUniformRoot::Module(
1958 self.resolve_self(&mut ctxt, parent_scope.module)));
1961 if name == kw::PathRoot && ident.span.rust_2018() {
1962 module = Some(ModuleOrUniformRoot::ExternPrelude);
1965 if name == kw::PathRoot &&
1966 ident.span.rust_2015() && self.session.rust_2018() {
1967 // `::a::b` from 2015 macro on 2018 global edition
1968 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
1971 if name == kw::PathRoot ||
1972 name == kw::Crate ||
1973 name == kw::DollarCrate {
1974 // `::a::b`, `crate::a::b` or `$crate::a::b`
1975 module = Some(ModuleOrUniformRoot::Module(
1976 self.resolve_crate_root(ident)));
1982 // Report special messages for path segment keywords in wrong positions.
1983 if ident.is_path_segment_keyword() && i != 0 {
1984 let name_str = if name == kw::PathRoot {
1985 "crate root".to_string()
1987 format!("`{}`", name)
1989 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
1990 format!("global paths cannot start with {}", name_str)
1992 format!("{} in paths can only be used in start position", name_str)
1994 return PathResult::Failed {
1998 is_error_from_last_segment: false,
2002 let binding = if let Some(module) = module {
2003 self.resolve_ident_in_module(
2004 module, ident, ns, parent_scope, record_used, path_span
2006 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2007 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2008 self.early_resolve_ident_in_lexical_scope(ident, scopes, parent_scope, record_used,
2009 record_used, path_span)
2011 let record_used_id =
2012 if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };
2013 match self.resolve_ident_in_lexical_scope(
2014 ident, ns, parent_scope, record_used_id, path_span, &ribs.unwrap()[ns]
2016 // we found a locally-imported or available item/module
2017 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2018 // we found a local variable or type param
2019 Some(LexicalScopeBinding::Res(res))
2020 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2021 record_segment_res(self, res);
2022 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2026 _ => Err(Determinacy::determined(record_used)),
2033 second_binding = Some(binding);
2035 let res = binding.res();
2036 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2037 if let Some(next_module) = binding.module() {
2038 module = Some(ModuleOrUniformRoot::Module(next_module));
2039 record_segment_res(self, res);
2040 } else if res == Res::ToolMod && i + 1 != path.len() {
2041 if binding.is_import() {
2042 self.session.struct_span_err(
2043 ident.span, "cannot use a tool module through an import"
2045 binding.span, "the tool module imported here"
2048 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2049 return PathResult::NonModule(PartialRes::new(res));
2050 } else if res == Res::Err {
2051 return PathResult::NonModule(PartialRes::new(Res::Err));
2052 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2053 self.lint_if_path_starts_with_module(
2059 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2060 res, path.len() - i - 1
2063 let label = format!(
2064 "`{}` is {} {}, not a module",
2070 return PathResult::Failed {
2074 is_error_from_last_segment: is_last,
2078 Err(Undetermined) => return PathResult::Indeterminate,
2079 Err(Determined) => {
2080 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2081 if opt_ns.is_some() && !module.is_normal() {
2082 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2083 module.res().unwrap(), path.len() - i
2087 let module_res = match module {
2088 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2091 let (label, suggestion) = if module_res == self.graph_root.res() {
2092 let is_mod = |res| {
2093 match res { Res::Def(DefKind::Mod, _) => true, _ => false }
2095 let mut candidates =
2096 self.lookup_import_candidates(ident, TypeNS, is_mod);
2097 candidates.sort_by_cached_key(|c| {
2098 (c.path.segments.len(), pprust::path_to_string(&c.path))
2100 if let Some(candidate) = candidates.get(0) {
2102 String::from("unresolved import"),
2104 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2105 String::from("a similar path exists"),
2106 Applicability::MaybeIncorrect,
2109 } else if !ident.is_reserved() {
2110 (format!("maybe a missing crate `{}`?", ident), None)
2112 // the parser will already have complained about the keyword being used
2113 return PathResult::NonModule(PartialRes::new(Res::Err));
2116 (format!("use of undeclared type or module `{}`", ident), None)
2118 (format!("could not find `{}` in `{}`", ident, path[i - 1].ident), None)
2120 return PathResult::Failed {
2124 is_error_from_last_segment: is_last,
2130 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2132 PathResult::Module(match module {
2133 Some(module) => module,
2134 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2135 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2139 fn lint_if_path_starts_with_module(
2141 crate_lint: CrateLint,
2144 second_binding: Option<&NameBinding<'_>>,
2146 let (diag_id, diag_span) = match crate_lint {
2147 CrateLint::No => return,
2148 CrateLint::SimplePath(id) => (id, path_span),
2149 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2150 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2153 let first_name = match path.get(0) {
2154 // In the 2018 edition this lint is a hard error, so nothing to do
2155 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2159 // We're only interested in `use` paths which should start with
2160 // `{{root}}` currently.
2161 if first_name != kw::PathRoot {
2166 // If this import looks like `crate::...` it's already good
2167 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2168 // Otherwise go below to see if it's an extern crate
2170 // If the path has length one (and it's `PathRoot` most likely)
2171 // then we don't know whether we're gonna be importing a crate or an
2172 // item in our crate. Defer this lint to elsewhere
2176 // If the first element of our path was actually resolved to an
2177 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2178 // warning, this looks all good!
2179 if let Some(binding) = second_binding {
2180 if let NameBindingKind::Import { directive: d, .. } = binding.kind {
2181 // Careful: we still want to rewrite paths from
2182 // renamed extern crates.
2183 if let ImportDirectiveSubclass::ExternCrate { source: None, .. } = d.subclass {
2189 let diag = lint::builtin::BuiltinLintDiagnostics
2190 ::AbsPathWithModule(diag_span);
2191 self.lint_buffer.buffer_lint_with_diagnostic(
2192 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2194 "absolute paths must start with `self`, `super`, \
2195 `crate`, or an external crate name in the 2018 edition",
2199 // Validate a local resolution (from ribs).
2200 fn validate_res_from_ribs(
2207 all_ribs: &[Rib<'a>],
2209 debug!("validate_res_from_ribs({:?})", res);
2210 let ribs = &all_ribs[rib_index + 1..];
2212 // An invalid forward use of a type parameter from a previous default.
2213 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2215 let res_error = if rib_ident.name == kw::SelfUpper {
2216 ResolutionError::SelfInTyParamDefault
2218 ResolutionError::ForwardDeclaredTyParam
2220 self.report_error(span, res_error);
2222 assert_eq!(res, Res::Err);
2228 use ResolutionError::*;
2229 let mut res_err = None;
2233 NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2234 ForwardTyParamBanRibKind => {
2235 // Nothing to do. Continue.
2237 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2238 // This was an attempt to access an upvar inside a
2239 // named function item. This is not allowed, so we
2242 // We don't immediately trigger a resolve error, because
2243 // we want certain other resolution errors (namely those
2244 // emitted for `ConstantItemRibKind` below) to take
2246 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2249 ConstantItemRibKind => {
2250 // Still doesn't deal with upvars
2252 self.report_error(span, AttemptToUseNonConstantValueInConstant);
2258 if let Some(res_err) = res_err {
2259 self.report_error(span, res_err);
2263 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2265 let has_generic_params = match rib.kind {
2266 NormalRibKind | AssocItemRibKind |
2267 ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2268 ConstantItemRibKind => {
2269 // Nothing to do. Continue.
2272 // This was an attempt to use a type parameter outside its scope.
2273 ItemRibKind(has_generic_params) => has_generic_params,
2274 FnItemRibKind => HasGenericParams::Yes,
2278 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2279 res, has_generic_params));
2284 Res::Def(DefKind::ConstParam, _) => {
2285 let mut ribs = ribs.iter().peekable();
2286 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2287 // When declaring const parameters inside function signatures, the first rib
2288 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2289 // (spuriously) conflicting with the const param.
2293 let has_generic_params = match rib.kind {
2294 ItemRibKind(has_generic_params) => has_generic_params,
2295 FnItemRibKind => HasGenericParams::Yes,
2299 // This was an attempt to use a const parameter outside its scope.
2301 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2302 res, has_generic_params));
2312 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2313 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2314 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2315 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2319 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2320 vis.is_accessible_from(module.normal_ancestor_id, self)
2323 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2324 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2325 if !ptr::eq(module, old_module) {
2326 span_bug!(binding.span, "parent module is reset for binding");
2331 fn disambiguate_legacy_vs_modern(
2333 legacy: &'a NameBinding<'a>,
2334 modern: &'a NameBinding<'a>,
2336 // Some non-controversial subset of ambiguities "modern macro name" vs "macro_rules"
2337 // is disambiguated to mitigate regressions from macro modularization.
2338 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2339 match (self.binding_parent_modules.get(&PtrKey(legacy)),
2340 self.binding_parent_modules.get(&PtrKey(modern))) {
2341 (Some(legacy), Some(modern)) =>
2342 legacy.normal_ancestor_id == modern.normal_ancestor_id &&
2343 modern.is_ancestor_of(legacy),
2348 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
2350 if b.span.is_dummy() {
2351 let add_built_in = match b.res() {
2352 // These already contain the "built-in" prefix or look bad with it.
2353 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
2356 let (built_in, from) = if from_prelude {
2357 ("", " from prelude")
2358 } else if b.is_extern_crate() && !b.is_import() &&
2359 self.session.opts.externs.get(&ident.as_str()).is_some() {
2360 ("", " passed with `--extern`")
2361 } else if add_built_in {
2367 let article = if built_in.is_empty() { res.article() } else { "a" };
2368 format!("{a}{built_in} {thing}{from}",
2369 a = article, thing = res.descr(), built_in = built_in, from = from)
2371 let introduced = if b.is_import() { "imported" } else { "defined" };
2372 format!("the {thing} {introduced} here",
2373 thing = res.descr(), introduced = introduced)
2377 fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
2378 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
2379 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
2380 // We have to print the span-less alternative first, otherwise formatting looks bad.
2381 (b2, b1, misc2, misc1, true)
2383 (b1, b2, misc1, misc2, false)
2386 let mut err = struct_span_err!(self.session, ident.span, E0659,
2387 "`{ident}` is ambiguous ({why})",
2388 ident = ident, why = kind.descr());
2389 err.span_label(ident.span, "ambiguous name");
2391 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
2392 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
2393 let note_msg = format!("`{ident}` could{also} refer to {what}",
2394 ident = ident, also = also, what = what);
2396 let thing = b.res().descr();
2397 let mut help_msgs = Vec::new();
2398 if b.is_glob_import() && (kind == AmbiguityKind::GlobVsGlob ||
2399 kind == AmbiguityKind::GlobVsExpanded ||
2400 kind == AmbiguityKind::GlobVsOuter &&
2401 swapped != also.is_empty()) {
2402 help_msgs.push(format!("consider adding an explicit import of \
2403 `{ident}` to disambiguate", ident = ident))
2405 if b.is_extern_crate() && ident.span.rust_2018() {
2406 help_msgs.push(format!(
2407 "use `::{ident}` to refer to this {thing} unambiguously",
2408 ident = ident, thing = thing,
2411 if misc == AmbiguityErrorMisc::SuggestCrate {
2412 help_msgs.push(format!(
2413 "use `crate::{ident}` to refer to this {thing} unambiguously",
2414 ident = ident, thing = thing,
2416 } else if misc == AmbiguityErrorMisc::SuggestSelf {
2417 help_msgs.push(format!(
2418 "use `self::{ident}` to refer to this {thing} unambiguously",
2419 ident = ident, thing = thing,
2423 err.span_note(b.span, ¬e_msg);
2424 for (i, help_msg) in help_msgs.iter().enumerate() {
2425 let or = if i == 0 { "" } else { "or " };
2426 err.help(&format!("{}{}", or, help_msg));
2430 could_refer_to(b1, misc1, "");
2431 could_refer_to(b2, misc2, " also");
2435 fn report_errors(&mut self, krate: &Crate) {
2436 self.report_with_use_injections(krate);
2438 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2439 let msg = "macro-expanded `macro_export` macros from the current crate \
2440 cannot be referred to by absolute paths";
2441 self.lint_buffer.buffer_lint_with_diagnostic(
2442 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2443 CRATE_NODE_ID, span_use, msg,
2444 lint::builtin::BuiltinLintDiagnostics::
2445 MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2449 for ambiguity_error in &self.ambiguity_errors {
2450 self.report_ambiguity_error(ambiguity_error);
2453 let mut reported_spans = FxHashSet::default();
2454 for &PrivacyError(dedup_span, ident, binding) in &self.privacy_errors {
2455 if reported_spans.insert(dedup_span) {
2456 let session = &self.session;
2457 let mk_struct_span_error = |is_constructor| {
2462 "{}{} `{}` is private",
2463 binding.res().descr(),
2464 if is_constructor { " constructor"} else { "" },
2469 let mut err = if let NameBindingKind::Res(
2470 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _
2472 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
2473 if let Some(fields) = self.field_names.get(&def_id) {
2474 let mut err = mk_struct_span_error(true);
2475 let first_field = fields.first().expect("empty field list in the map");
2477 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
2478 "a constructor is private if any of the fields is private",
2482 mk_struct_span_error(false)
2485 mk_struct_span_error(false)
2493 fn report_with_use_injections(&mut self, krate: &Crate) {
2494 for UseError { mut err, candidates, node_id, better } in self.use_injections.drain(..) {
2495 let (span, found_use) = UsePlacementFinder::check(krate, node_id);
2496 if !candidates.is_empty() {
2497 diagnostics::show_candidates(&mut err, span, &candidates, better, found_use);
2503 fn report_conflict<'b>(&mut self,
2507 new_binding: &NameBinding<'b>,
2508 old_binding: &NameBinding<'b>) {
2509 // Error on the second of two conflicting names
2510 if old_binding.span.lo() > new_binding.span.lo() {
2511 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2514 let container = match parent.kind {
2515 ModuleKind::Def(DefKind::Mod, _, _) => "module",
2516 ModuleKind::Def(DefKind::Trait, _, _) => "trait",
2517 ModuleKind::Block(..) => "block",
2521 let old_noun = match old_binding.is_import() {
2523 false => "definition",
2526 let new_participle = match new_binding.is_import() {
2531 let (name, span) = (ident.name, self.session.source_map().def_span(new_binding.span));
2533 if let Some(s) = self.name_already_seen.get(&name) {
2539 let old_kind = match (ns, old_binding.module()) {
2540 (ValueNS, _) => "value",
2541 (MacroNS, _) => "macro",
2542 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2543 (TypeNS, Some(module)) if module.is_normal() => "module",
2544 (TypeNS, Some(module)) if module.is_trait() => "trait",
2545 (TypeNS, _) => "type",
2548 let msg = format!("the name `{}` is defined multiple times", name);
2550 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2551 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2552 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2553 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2554 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2556 _ => match (old_binding.is_import(), new_binding.is_import()) {
2557 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2558 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2559 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2563 err.note(&format!("`{}` must be defined only once in the {} namespace of this {}",
2568 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2570 self.session.source_map().def_span(old_binding.span),
2571 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2574 // See https://github.com/rust-lang/rust/issues/32354
2575 use NameBindingKind::Import;
2576 let directive = match (&new_binding.kind, &old_binding.kind) {
2577 // If there are two imports where one or both have attributes then prefer removing the
2578 // import without attributes.
2579 (Import { directive: new, .. }, Import { directive: old, .. }) if {
2580 !new_binding.span.is_dummy() && !old_binding.span.is_dummy() &&
2581 (new.has_attributes || old.has_attributes)
2583 if old.has_attributes {
2584 Some((new, new_binding.span, true))
2586 Some((old, old_binding.span, true))
2589 // Otherwise prioritize the new binding.
2590 (Import { directive, .. }, other) if !new_binding.span.is_dummy() =>
2591 Some((directive, new_binding.span, other.is_import())),
2592 (other, Import { directive, .. }) if !old_binding.span.is_dummy() =>
2593 Some((directive, old_binding.span, other.is_import())),
2597 // Check if the target of the use for both bindings is the same.
2598 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2599 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2600 let from_item = self.extern_prelude.get(&ident)
2601 .map(|entry| entry.introduced_by_item)
2603 // Only suggest removing an import if both bindings are to the same def, if both spans
2604 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2605 // been introduced by a item.
2606 let should_remove_import = duplicate && !has_dummy_span &&
2607 ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2610 Some((directive, span, true)) if should_remove_import && directive.is_nested() =>
2611 self.add_suggestion_for_duplicate_nested_use(&mut err, directive, span),
2612 Some((directive, _, true)) if should_remove_import && !directive.is_glob() => {
2613 // Simple case - remove the entire import. Due to the above match arm, this can
2614 // only be a single use so just remove it entirely.
2615 err.tool_only_span_suggestion(
2616 directive.use_span_with_attributes,
2617 "remove unnecessary import",
2619 Applicability::MaybeIncorrect,
2622 Some((directive, span, _)) =>
2623 self.add_suggestion_for_rename_of_use(&mut err, name, directive, span),
2628 self.name_already_seen.insert(name, span);
2631 /// This function adds a suggestion to change the binding name of a new import that conflicts
2632 /// with an existing import.
2634 /// ```ignore (diagnostic)
2635 /// help: you can use `as` to change the binding name of the import
2637 /// LL | use foo::bar as other_bar;
2638 /// | ^^^^^^^^^^^^^^^^^^^^^
2640 fn add_suggestion_for_rename_of_use(
2642 err: &mut DiagnosticBuilder<'_>,
2644 directive: &ImportDirective<'_>,
2647 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
2648 format!("Other{}", name)
2650 format!("other_{}", name)
2653 let mut suggestion = None;
2654 match directive.subclass {
2655 ImportDirectiveSubclass::SingleImport { type_ns_only: true, .. } =>
2656 suggestion = Some(format!("self as {}", suggested_name)),
2657 ImportDirectiveSubclass::SingleImport { source, .. } => {
2658 if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0)
2659 .map(|pos| pos as usize) {
2660 if let Ok(snippet) = self.session.source_map()
2661 .span_to_snippet(binding_span) {
2662 if pos <= snippet.len() {
2663 suggestion = Some(format!(
2667 if snippet.ends_with(";") { ";" } else { "" }
2673 ImportDirectiveSubclass::ExternCrate { source, target, .. } =>
2674 suggestion = Some(format!(
2675 "extern crate {} as {};",
2676 source.unwrap_or(target.name),
2679 _ => unreachable!(),
2682 let rename_msg = "you can use `as` to change the binding name of the import";
2683 if let Some(suggestion) = suggestion {
2684 err.span_suggestion(
2688 Applicability::MaybeIncorrect,
2691 err.span_label(binding_span, rename_msg);
2695 /// This function adds a suggestion to remove a unnecessary binding from an import that is
2696 /// nested. In the following example, this function will be invoked to remove the `a` binding
2697 /// in the second use statement:
2699 /// ```ignore (diagnostic)
2700 /// use issue_52891::a;
2701 /// use issue_52891::{d, a, e};
2704 /// The following suggestion will be added:
2706 /// ```ignore (diagnostic)
2707 /// use issue_52891::{d, a, e};
2708 /// ^-- help: remove unnecessary import
2711 /// If the nested use contains only one import then the suggestion will remove the entire
2714 /// It is expected that the directive provided is a nested import - this isn't checked by the
2715 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
2716 /// as characters expected by span manipulations won't be present.
2717 fn add_suggestion_for_duplicate_nested_use(
2719 err: &mut DiagnosticBuilder<'_>,
2720 directive: &ImportDirective<'_>,
2723 assert!(directive.is_nested());
2724 let message = "remove unnecessary import";
2726 // Two examples will be used to illustrate the span manipulations we're doing:
2728 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
2729 // `a` and `directive.use_span` is `issue_52891::{d, a, e};`.
2730 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
2731 // `a` and `directive.use_span` is `issue_52891::{d, e, a};`.
2733 let (found_closing_brace, span) = find_span_of_binding_until_next_binding(
2734 self.session, binding_span, directive.use_span,
2737 // If there was a closing brace then identify the span to remove any trailing commas from
2738 // previous imports.
2739 if found_closing_brace {
2740 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
2741 err.tool_only_span_suggestion(span, message, String::new(),
2742 Applicability::MaybeIncorrect);
2744 // Remove the entire line if we cannot extend the span back, this indicates a
2745 // `issue_52891::{self}` case.
2746 err.span_suggestion(directive.use_span_with_attributes, message, String::new(),
2747 Applicability::MaybeIncorrect);
2753 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
2756 fn extern_prelude_get(&mut self, ident: Ident, speculative: bool)
2757 -> Option<&'a NameBinding<'a>> {
2758 if ident.is_path_segment_keyword() {
2759 // Make sure `self`, `super` etc produce an error when passed to here.
2762 self.extern_prelude.get(&ident.modern()).cloned().and_then(|entry| {
2763 if let Some(binding) = entry.extern_crate_item {
2764 if !speculative && entry.introduced_by_item {
2765 self.record_use(ident, TypeNS, binding, false);
2769 let crate_id = if !speculative {
2770 self.crate_loader.process_path_extern(ident.name, ident.span)
2771 } else if let Some(crate_id) =
2772 self.crate_loader.maybe_process_path_extern(ident.name, ident.span) {
2777 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
2778 Some((crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
2779 .to_name_binding(self.arenas))
2784 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
2785 /// isn't something that can be returned because it can't be made to live that long,
2786 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
2787 /// just that an error occurred.
2788 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
2789 pub fn resolve_str_path_error(
2790 &mut self, span: Span, path_str: &str, ns: Namespace, module_id: NodeId
2791 ) -> Result<(ast::Path, Res), ()> {
2792 let path = if path_str.starts_with("::") {
2795 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
2797 path_str.split("::").skip(1).map(Ident::from_str)
2799 .map(|i| self.new_ast_path_segment(i))
2807 .map(Ident::from_str)
2808 .map(|i| self.new_ast_path_segment(i))
2812 let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| {
2813 let def_id = self.definitions.local_def_id(module_id);
2814 self.module_map.get(&def_id).copied().unwrap_or(self.graph_root)
2816 let parent_scope = &ParentScope::module(module);
2817 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
2821 // Resolve a path passed from rustdoc or HIR lowering.
2822 fn resolve_ast_path(
2826 parent_scope: &ParentScope<'a>,
2827 ) -> Result<Res, (Span, ResolutionError<'a>)> {
2828 match self.resolve_path(
2829 &Segment::from_path(path), Some(ns), parent_scope, true, path.span, CrateLint::No
2831 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
2832 Ok(module.res().unwrap()),
2833 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
2834 Ok(path_res.base_res()),
2835 PathResult::NonModule(..) => {
2836 Err((path.span, ResolutionError::FailedToResolve {
2837 label: String::from("type-relative paths are not supported in this context"),
2841 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
2842 PathResult::Failed { span, label, suggestion, .. } => {
2843 Err((span, ResolutionError::FailedToResolve {
2851 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
2852 let mut seg = ast::PathSegment::from_ident(ident);
2853 seg.id = self.next_node_id();
2858 pub fn graph_root(&self) -> Module<'a> {
2863 pub fn all_macros(&self) -> &FxHashMap<Name, Res> {
2868 fn names_to_string(names: &[Name]) -> String {
2869 let mut result = String::new();
2870 for (i, name) in names.iter()
2871 .filter(|name| **name != kw::PathRoot)
2874 result.push_str("::");
2876 result.push_str(&name.as_str());
2881 fn path_names_to_string(path: &Path) -> String {
2882 names_to_string(&path.segments.iter()
2883 .map(|seg| seg.ident.name)
2884 .collect::<Vec<_>>())
2887 /// A somewhat inefficient routine to obtain the name of a module.
2888 fn module_to_string(module: Module<'_>) -> Option<String> {
2889 let mut names = Vec::new();
2891 fn collect_mod(names: &mut Vec<Name>, module: Module<'_>) {
2892 if let ModuleKind::Def(.., name) = module.kind {
2893 if let Some(parent) = module.parent {
2895 collect_mod(names, parent);
2898 names.push(Name::intern("<opaque>"));
2899 collect_mod(names, module.parent.unwrap());
2902 collect_mod(&mut names, module);
2904 if names.is_empty() {
2908 Some(names_to_string(&names))
2911 #[derive(Copy, Clone, Debug)]
2913 /// Do not issue the lint.
2916 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
2917 /// In this case, we can take the span of that path.
2920 /// This lint comes from a `use` statement. In this case, what we
2921 /// care about really is the *root* `use` statement; e.g., if we
2922 /// have nested things like `use a::{b, c}`, we care about the
2924 UsePath { root_id: NodeId, root_span: Span },
2926 /// This is the "trait item" from a fully qualified path. For example,
2927 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
2928 /// The `path_span` is the span of the to the trait itself (`X::Y`).
2929 QPathTrait { qpath_id: NodeId, qpath_span: Span },
2933 fn node_id(&self) -> Option<NodeId> {
2935 CrateLint::No => None,
2936 CrateLint::SimplePath(id) |
2937 CrateLint::UsePath { root_id: id, .. } |
2938 CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),