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, ExpnKind, 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)]
100 DeriveHelpers(ExpnId),
102 MacroRules(LegacyScope<'a>),
115 /// Names from different contexts may want to visit different subsets of all specific scopes
116 /// with different restrictions when looking up the resolution.
117 /// This enum is currently used only for early resolution (imports and macros),
118 /// but not for late resolution yet.
120 /// All scopes with the given namespace.
121 All(Namespace, /*is_import*/ bool),
122 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
123 AbsolutePath(Namespace),
124 /// All scopes with macro namespace and the given macro kind restriction.
128 /// Everything you need to know about a name's location to resolve it.
129 /// Serves as a starting point for the scope visitor.
130 /// This struct is currently used only for early resolution (imports and macros),
131 /// but not for late resolution yet.
132 #[derive(Clone, Copy, Debug)]
133 pub struct ParentScope<'a> {
136 legacy: LegacyScope<'a>,
137 derives: &'a [ast::Path],
140 impl<'a> ParentScope<'a> {
141 /// Creates a parent scope with the passed argument used as the module scope component,
142 /// and other scope components set to default empty values.
143 pub fn module(module: Module<'a>) -> ParentScope<'a> {
146 expansion: ExpnId::root(),
147 legacy: LegacyScope::Empty,
154 struct BindingError {
156 origin: BTreeSet<Span>,
157 target: BTreeSet<Span>,
161 impl PartialOrd for BindingError {
162 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
163 Some(self.cmp(other))
167 impl PartialEq for BindingError {
168 fn eq(&self, other: &BindingError) -> bool {
169 self.name == other.name
173 impl Ord for BindingError {
174 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
175 self.name.cmp(&other.name)
179 enum ResolutionError<'a> {
180 /// Error E0401: can't use type or const parameters from outer function.
181 GenericParamsFromOuterFunction(Res, HasGenericParams),
182 /// Error E0403: the name is already used for a type or const parameter in this generic
184 NameAlreadyUsedInParameterList(Name, Span),
185 /// Error E0407: method is not a member of trait.
186 MethodNotMemberOfTrait(Name, &'a str),
187 /// Error E0437: type is not a member of trait.
188 TypeNotMemberOfTrait(Name, &'a str),
189 /// Error E0438: const is not a member of trait.
190 ConstNotMemberOfTrait(Name, &'a str),
191 /// Error E0408: variable `{}` is not bound in all patterns.
192 VariableNotBoundInPattern(&'a BindingError),
193 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
194 VariableBoundWithDifferentMode(Name, Span),
195 /// Error E0415: identifier is bound more than once in this parameter list.
196 IdentifierBoundMoreThanOnceInParameterList(&'a str),
197 /// Error E0416: identifier is bound more than once in the same pattern.
198 IdentifierBoundMoreThanOnceInSamePattern(&'a str),
199 /// Error E0426: use of undeclared label.
200 UndeclaredLabel(&'a str, Option<Name>),
201 /// Error E0429: `self` imports are only allowed within a `{ }` list.
202 SelfImportsOnlyAllowedWithin,
203 /// Error E0430: `self` import can only appear once in the list.
204 SelfImportCanOnlyAppearOnceInTheList,
205 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
206 SelfImportOnlyInImportListWithNonEmptyPrefix,
207 /// Error E0433: failed to resolve.
208 FailedToResolve { label: String, suggestion: Option<Suggestion> },
209 /// Error E0434: can't capture dynamic environment in a fn item.
210 CannotCaptureDynamicEnvironmentInFnItem,
211 /// Error E0435: attempt to use a non-constant value in a constant.
212 AttemptToUseNonConstantValueInConstant,
213 /// Error E0530: `X` bindings cannot shadow `Y`s.
214 BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
215 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
216 ForwardDeclaredTyParam, // FIXME(const_generics:defaults)
217 /// Error E0735: type parameters with a default cannot use `Self`
218 SelfInTyParamDefault,
221 // A minimal representation of a path segment. We use this in resolve because
222 // we synthesize 'path segments' which don't have the rest of an AST or HIR
224 #[derive(Clone, Copy, Debug)]
231 fn from_path(path: &Path) -> Vec<Segment> {
232 path.segments.iter().map(|s| s.into()).collect()
235 fn from_ident(ident: Ident) -> Segment {
242 fn names_to_string(segments: &[Segment]) -> String {
243 names_to_string(&segments.iter()
244 .map(|seg| seg.ident.name)
245 .collect::<Vec<_>>())
249 impl<'a> From<&'a ast::PathSegment> for Segment {
250 fn from(seg: &'a ast::PathSegment) -> Segment {
258 struct UsePlacementFinder {
259 target_module: NodeId,
264 impl UsePlacementFinder {
265 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
266 let mut finder = UsePlacementFinder {
271 visit::walk_crate(&mut finder, krate);
272 (finder.span, finder.found_use)
276 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
279 module: &'tcx ast::Mod,
281 _: &[ast::Attribute],
284 if self.span.is_some() {
287 if node_id != self.target_module {
288 visit::walk_mod(self, module);
291 // find a use statement
292 for item in &module.items {
294 ItemKind::Use(..) => {
295 // don't suggest placing a use before the prelude
296 // import or other generated ones
297 if !item.span.from_expansion() {
298 self.span = Some(item.span.shrink_to_lo());
299 self.found_use = true;
303 // don't place use before extern crate
304 ItemKind::ExternCrate(_) => {}
305 // but place them before the first other item
306 _ => if self.span.map_or(true, |span| item.span < span ) {
307 if !item.span.from_expansion() {
308 // don't insert between attributes and an item
309 if item.attrs.is_empty() {
310 self.span = Some(item.span.shrink_to_lo());
312 // find the first attribute on the item
313 for attr in &item.attrs {
314 if self.span.map_or(true, |span| attr.span < span) {
315 self.span = Some(attr.span.shrink_to_lo());
326 /// An intermediate resolution result.
328 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
329 /// items are visible in their whole block, while `Res`es only from the place they are defined
332 enum LexicalScopeBinding<'a> {
333 Item(&'a NameBinding<'a>),
337 impl<'a> LexicalScopeBinding<'a> {
338 fn item(self) -> Option<&'a NameBinding<'a>> {
340 LexicalScopeBinding::Item(binding) => Some(binding),
345 fn res(self) -> Res {
347 LexicalScopeBinding::Item(binding) => binding.res(),
348 LexicalScopeBinding::Res(res) => res,
353 #[derive(Copy, Clone, Debug)]
354 enum ModuleOrUniformRoot<'a> {
358 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
359 CrateRootAndExternPrelude,
361 /// Virtual module that denotes resolution in extern prelude.
362 /// Used for paths starting with `::` on 2018 edition.
365 /// Virtual module that denotes resolution in current scope.
366 /// Used only for resolving single-segment imports. The reason it exists is that import paths
367 /// are always split into two parts, the first of which should be some kind of module.
371 impl ModuleOrUniformRoot<'_> {
372 fn same_def(lhs: Self, rhs: Self) -> bool {
374 (ModuleOrUniformRoot::Module(lhs),
375 ModuleOrUniformRoot::Module(rhs)) => lhs.def_id() == rhs.def_id(),
376 (ModuleOrUniformRoot::CrateRootAndExternPrelude,
377 ModuleOrUniformRoot::CrateRootAndExternPrelude) |
378 (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) |
379 (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
385 #[derive(Clone, Debug)]
386 enum PathResult<'a> {
387 Module(ModuleOrUniformRoot<'a>),
388 NonModule(PartialRes),
393 suggestion: Option<Suggestion>,
394 is_error_from_last_segment: bool,
399 /// An anonymous module; e.g., just a block.
404 /// { // This is an anonymous module
405 /// f(); // This resolves to (2) as we are inside the block.
408 /// f(); // Resolves to (1)
412 /// Any module with a name.
416 /// * A normal module ‒ either `mod from_file;` or `mod from_block { }`.
417 /// * A trait or an enum (it implicitly contains associated types, methods and variant
419 Def(DefKind, DefId, Name),
423 /// Get name of the module.
424 pub fn name(&self) -> Option<Name> {
426 ModuleKind::Block(..) => None,
427 ModuleKind::Def(.., name) => Some(*name),
432 /// A key that identifies a binding in a given `Module`.
434 /// Multiple bindings in the same module can have the same key (in a valid
435 /// program) if all but one of them come from glob imports.
436 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
438 /// The identifier for the binding, aways the `modern` version of the
442 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
443 /// `_` in the expanded AST that introduced this binding.
447 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
449 /// One node in the tree of modules.
450 pub struct ModuleData<'a> {
451 parent: Option<Module<'a>>,
454 // The def id of the closest normal module (`mod`) ancestor (including this module).
455 normal_ancestor_id: DefId,
457 // Mapping between names and their (possibly in-progress) resolutions in this module.
458 // Resolutions in modules from other crates are not populated until accessed.
459 lazy_resolutions: Resolutions<'a>,
460 // True if this is a module from other crate that needs to be populated on access.
461 populate_on_access: Cell<bool>,
463 // Macro invocations that can expand into items in this module.
464 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
466 no_implicit_prelude: bool,
468 glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
469 globs: RefCell<Vec<&'a ImportDirective<'a>>>,
471 // Used to memoize the traits in this module for faster searches through all traits in scope.
472 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
474 /// Span of the module itself. Used for error reporting.
480 type Module<'a> = &'a ModuleData<'a>;
482 impl<'a> ModuleData<'a> {
483 fn new(parent: Option<Module<'a>>,
485 normal_ancestor_id: DefId,
487 span: Span) -> Self {
492 lazy_resolutions: Default::default(),
493 populate_on_access: Cell::new(!normal_ancestor_id.is_local()),
494 unexpanded_invocations: Default::default(),
495 no_implicit_prelude: false,
496 glob_importers: RefCell::new(Vec::new()),
497 globs: RefCell::new(Vec::new()),
498 traits: RefCell::new(None),
504 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
505 where R: AsMut<Resolver<'a>>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>)
507 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
508 name_resolution.borrow().binding.map(|binding| f(resolver, key.ident, key.ns, binding));
512 fn res(&self) -> Option<Res> {
514 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
519 fn def_id(&self) -> Option<DefId> {
521 ModuleKind::Def(_, def_id, _) => Some(def_id),
526 // `self` resolves to the first module ancestor that `is_normal`.
527 fn is_normal(&self) -> bool {
529 ModuleKind::Def(DefKind::Mod, _, _) => true,
534 fn is_trait(&self) -> bool {
536 ModuleKind::Def(DefKind::Trait, _, _) => true,
541 fn nearest_item_scope(&'a self) -> Module<'a> {
543 ModuleKind::Def(DefKind::Enum, ..) | ModuleKind::Def(DefKind::Trait, ..) =>
544 self.parent.expect("enum or trait module without a parent"),
549 fn is_ancestor_of(&self, mut other: &Self) -> bool {
550 while !ptr::eq(self, other) {
551 if let Some(parent) = other.parent {
561 impl<'a> fmt::Debug for ModuleData<'a> {
562 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
563 write!(f, "{:?}", self.res())
567 /// Records a possibly-private value, type, or module definition.
568 #[derive(Clone, Debug)]
569 pub struct NameBinding<'a> {
570 kind: NameBindingKind<'a>,
571 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
577 pub trait ToNameBinding<'a> {
578 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
581 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
582 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
587 #[derive(Clone, Debug)]
588 enum NameBindingKind<'a> {
589 Res(Res, /* is_macro_export */ bool),
592 binding: &'a NameBinding<'a>,
593 directive: &'a ImportDirective<'a>,
598 impl<'a> NameBindingKind<'a> {
599 /// Is this a name binding of a import?
600 fn is_import(&self) -> bool {
602 NameBindingKind::Import { .. } => true,
608 struct PrivacyError<'a>(Span, Ident, &'a NameBinding<'a>);
610 struct UseError<'a> {
611 err: DiagnosticBuilder<'a>,
612 /// Attach `use` statements for these candidates.
613 candidates: Vec<ImportSuggestion>,
614 /// The `NodeId` of the module to place the use-statements in.
616 /// Whether the diagnostic should state that it's "better".
620 #[derive(Clone, Copy, PartialEq, Debug)]
633 fn descr(self) -> &'static str {
635 AmbiguityKind::Import =>
636 "name vs any other name during import resolution",
637 AmbiguityKind::BuiltinAttr =>
638 "built-in attribute vs any other name",
639 AmbiguityKind::DeriveHelper =>
640 "derive helper attribute vs any other name",
641 AmbiguityKind::LegacyVsModern =>
642 "`macro_rules` vs non-`macro_rules` from other module",
643 AmbiguityKind::GlobVsOuter =>
644 "glob import vs any other name from outer scope during import/macro resolution",
645 AmbiguityKind::GlobVsGlob =>
646 "glob import vs glob import in the same module",
647 AmbiguityKind::GlobVsExpanded =>
648 "glob import vs macro-expanded name in the same \
649 module during import/macro resolution",
650 AmbiguityKind::MoreExpandedVsOuter =>
651 "macro-expanded name vs less macro-expanded name \
652 from outer scope during import/macro resolution",
657 /// Miscellaneous bits of metadata for better ambiguity error reporting.
658 #[derive(Clone, Copy, PartialEq)]
659 enum AmbiguityErrorMisc {
666 struct AmbiguityError<'a> {
669 b1: &'a NameBinding<'a>,
670 b2: &'a NameBinding<'a>,
671 misc1: AmbiguityErrorMisc,
672 misc2: AmbiguityErrorMisc,
675 impl<'a> NameBinding<'a> {
676 fn module(&self) -> Option<Module<'a>> {
678 NameBindingKind::Module(module) => Some(module),
679 NameBindingKind::Import { binding, .. } => binding.module(),
684 fn res(&self) -> Res {
686 NameBindingKind::Res(res, _) => res,
687 NameBindingKind::Module(module) => module.res().unwrap(),
688 NameBindingKind::Import { binding, .. } => binding.res(),
692 fn is_ambiguity(&self) -> bool {
693 self.ambiguity.is_some() || match self.kind {
694 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
699 // We sometimes need to treat variants as `pub` for backwards compatibility.
700 fn pseudo_vis(&self) -> ty::Visibility {
701 if self.is_variant() && self.res().def_id().is_local() {
702 ty::Visibility::Public
708 fn is_variant(&self) -> bool {
710 NameBindingKind::Res(Res::Def(DefKind::Variant, _), _) |
711 NameBindingKind::Res(Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _), _) => true,
716 fn is_extern_crate(&self) -> bool {
718 NameBindingKind::Import {
719 directive: &ImportDirective {
720 subclass: ImportDirectiveSubclass::ExternCrate { .. }, ..
723 NameBindingKind::Module(
724 &ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }
725 ) => def_id.index == CRATE_DEF_INDEX,
730 fn is_import(&self) -> bool {
732 NameBindingKind::Import { .. } => true,
737 fn is_glob_import(&self) -> bool {
739 NameBindingKind::Import { directive, .. } => directive.is_glob(),
744 fn is_importable(&self) -> bool {
746 Res::Def(DefKind::AssocConst, _)
747 | Res::Def(DefKind::Method, _)
748 | Res::Def(DefKind::AssocTy, _) => false,
753 fn is_macro_def(&self) -> bool {
755 NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true,
760 fn macro_kind(&self) -> Option<MacroKind> {
761 self.res().macro_kind()
764 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
765 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
766 // Then this function returns `true` if `self` may emerge from a macro *after* that
767 // in some later round and screw up our previously found resolution.
768 // See more detailed explanation in
769 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
770 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
771 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
772 // Expansions are partially ordered, so "may appear after" is an inversion of
773 // "certainly appears before or simultaneously" and includes unordered cases.
774 let self_parent_expansion = self.expansion;
775 let other_parent_expansion = binding.expansion;
776 let certainly_before_other_or_simultaneously =
777 other_parent_expansion.is_descendant_of(self_parent_expansion);
778 let certainly_before_invoc_or_simultaneously =
779 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
780 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
784 /// Interns the names of the primitive types.
786 /// All other types are defined somewhere and possibly imported, but the primitive ones need
787 /// special handling, since they have no place of origin.
788 struct PrimitiveTypeTable {
789 primitive_types: FxHashMap<Name, PrimTy>,
792 impl PrimitiveTypeTable {
793 fn new() -> PrimitiveTypeTable {
794 let mut table = FxHashMap::default();
796 table.insert(sym::bool, Bool);
797 table.insert(sym::char, Char);
798 table.insert(sym::f32, Float(FloatTy::F32));
799 table.insert(sym::f64, Float(FloatTy::F64));
800 table.insert(sym::isize, Int(IntTy::Isize));
801 table.insert(sym::i8, Int(IntTy::I8));
802 table.insert(sym::i16, Int(IntTy::I16));
803 table.insert(sym::i32, Int(IntTy::I32));
804 table.insert(sym::i64, Int(IntTy::I64));
805 table.insert(sym::i128, Int(IntTy::I128));
806 table.insert(sym::str, Str);
807 table.insert(sym::usize, Uint(UintTy::Usize));
808 table.insert(sym::u8, Uint(UintTy::U8));
809 table.insert(sym::u16, Uint(UintTy::U16));
810 table.insert(sym::u32, Uint(UintTy::U32));
811 table.insert(sym::u64, Uint(UintTy::U64));
812 table.insert(sym::u128, Uint(UintTy::U128));
813 Self { primitive_types: table }
817 #[derive(Debug, Default, Clone)]
818 pub struct ExternPreludeEntry<'a> {
819 extern_crate_item: Option<&'a NameBinding<'a>>,
820 pub introduced_by_item: bool,
823 /// The main resolver class.
825 /// This is the visitor that walks the whole crate.
826 pub struct Resolver<'a> {
827 session: &'a Session,
829 definitions: Definitions,
831 graph_root: Module<'a>,
833 prelude: Option<Module<'a>>,
834 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
836 /// N.B., this is used only for better diagnostics, not name resolution itself.
837 has_self: FxHashSet<DefId>,
839 /// Names of fields of an item `DefId` accessible with dot syntax.
840 /// Used for hints during error reporting.
841 field_names: FxHashMap<DefId, Vec<Spanned<Name>>>,
843 /// All imports known to succeed or fail.
844 determined_imports: Vec<&'a ImportDirective<'a>>,
846 /// All non-determined imports.
847 indeterminate_imports: Vec<&'a ImportDirective<'a>>,
849 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
850 /// We are resolving a last import segment during import validation.
851 last_import_segment: bool,
852 /// This binding should be ignored during in-module resolution, so that we don't get
853 /// "self-confirming" import resolutions during import validation.
854 blacklisted_binding: Option<&'a NameBinding<'a>>,
856 /// The idents for the primitive types.
857 primitive_type_table: PrimitiveTypeTable,
859 /// Resolutions for nodes that have a single resolution.
860 partial_res_map: NodeMap<PartialRes>,
861 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
862 import_res_map: NodeMap<PerNS<Option<Res>>>,
863 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
864 label_res_map: NodeMap<NodeId>,
866 /// `CrateNum` resolutions of `extern crate` items.
867 extern_crate_map: NodeMap<CrateNum>,
868 export_map: ExportMap<NodeId>,
871 /// A map from nodes to anonymous modules.
872 /// Anonymous modules are pseudo-modules that are implicitly created around items
873 /// contained within blocks.
875 /// For example, if we have this:
883 /// There will be an anonymous module created around `g` with the ID of the
884 /// entry block for `f`.
885 block_map: NodeMap<Module<'a>>,
886 /// A fake module that contains no definition and no prelude. Used so that
887 /// some AST passes can generate identifiers that only resolve to local or
889 empty_module: Module<'a>,
890 module_map: FxHashMap<DefId, Module<'a>>,
891 extern_module_map: FxHashMap<DefId, Module<'a>>,
892 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
893 underscore_disambiguator: u32,
895 /// Maps glob imports to the names of items actually imported.
898 used_imports: FxHashSet<(NodeId, Namespace)>,
899 maybe_unused_trait_imports: NodeSet,
900 maybe_unused_extern_crates: Vec<(NodeId, Span)>,
902 /// Privacy errors are delayed until the end in order to deduplicate them.
903 privacy_errors: Vec<PrivacyError<'a>>,
904 /// Ambiguity errors are delayed for deduplication.
905 ambiguity_errors: Vec<AmbiguityError<'a>>,
906 /// `use` injections are delayed for better placement and deduplication.
907 use_injections: Vec<UseError<'a>>,
908 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
909 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
911 arenas: &'a ResolverArenas<'a>,
912 dummy_binding: &'a NameBinding<'a>,
914 crate_loader: CrateLoader<'a>,
915 macro_names: FxHashSet<Ident>,
916 builtin_macros: FxHashMap<Name, SyntaxExtension>,
917 registered_attrs: FxHashSet<Ident>,
918 registered_tools: FxHashSet<Ident>,
919 macro_use_prelude: FxHashMap<Name, &'a NameBinding<'a>>,
920 all_macros: FxHashMap<Name, Res>,
921 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
922 dummy_ext_bang: Lrc<SyntaxExtension>,
923 dummy_ext_derive: Lrc<SyntaxExtension>,
924 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
925 macro_defs: FxHashMap<ExpnId, DefId>,
926 local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
927 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
928 unused_macros: NodeMap<Span>,
929 proc_macro_stubs: NodeSet,
930 /// Traces collected during macro resolution and validated when it's complete.
931 single_segment_macro_resolutions: Vec<(Ident, MacroKind, ParentScope<'a>,
932 Option<&'a NameBinding<'a>>)>,
933 multi_segment_macro_resolutions: Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>,
935 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
936 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
937 /// Derive macros cannot modify the item themselves and have to store the markers in the global
938 /// context, so they attach the markers to derive container IDs using this resolver table.
939 containers_deriving_copy: FxHashSet<ExpnId>,
940 /// Parent scopes in which the macros were invoked.
941 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
942 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
943 /// Legacy scopes *produced* by expanding the macro invocations,
944 /// include all the `macro_rules` items and other invocations generated by them.
945 output_legacy_scopes: FxHashMap<ExpnId, LegacyScope<'a>>,
946 /// Helper attributes that are in scope for the given expansion.
947 helper_attrs: FxHashMap<ExpnId, Vec<Ident>>,
949 /// Avoid duplicated errors for "name already defined".
950 name_already_seen: FxHashMap<Name, Span>,
952 potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
954 /// Table for mapping struct IDs into struct constructor IDs,
955 /// it's not used during normal resolution, only for better error reporting.
956 struct_constructors: DefIdMap<(Res, ty::Visibility)>,
958 /// Features enabled for this crate.
959 active_features: FxHashSet<Name>,
961 /// Stores enum visibilities to properly build a reduced graph
962 /// when visiting the correspondent variants.
963 variant_vis: DefIdMap<ty::Visibility>,
965 lint_buffer: lint::LintBuffer,
967 next_node_id: NodeId,
970 /// Nothing really interesting here; it just provides memory for the rest of the crate.
972 pub struct ResolverArenas<'a> {
973 modules: arena::TypedArena<ModuleData<'a>>,
974 local_modules: RefCell<Vec<Module<'a>>>,
975 name_bindings: arena::TypedArena<NameBinding<'a>>,
976 import_directives: arena::TypedArena<ImportDirective<'a>>,
977 name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
978 legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
979 ast_paths: arena::TypedArena<ast::Path>,
982 impl<'a> ResolverArenas<'a> {
983 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
984 let module = self.modules.alloc(module);
985 if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
986 self.local_modules.borrow_mut().push(module);
990 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
991 self.local_modules.borrow()
993 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
994 self.name_bindings.alloc(name_binding)
996 fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
997 -> &'a ImportDirective<'_> {
998 self.import_directives.alloc(import_directive)
1000 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1001 self.name_resolutions.alloc(Default::default())
1003 fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1004 self.legacy_bindings.alloc(binding)
1006 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1007 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1011 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1012 fn as_mut(&mut self) -> &mut Resolver<'a> { self }
1015 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1016 fn parent(self, id: DefId) -> Option<DefId> {
1018 LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1019 _ => self.cstore().def_key(id).parent,
1020 }.map(|index| DefId { index, ..id })
1024 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1025 /// the resolver is no longer needed as all the relevant information is inline.
1026 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1027 fn cstore(&self) -> &dyn CrateStore {
1031 fn resolve_str_path(
1034 crate_root: Option<Name>,
1035 components: &[Name],
1037 ) -> (ast::Path, Res) {
1038 let root = if crate_root.is_some() {
1043 let segments = iter::once(Ident::with_dummy_span(root))
1045 crate_root.into_iter()
1046 .chain(components.iter().cloned())
1047 .map(Ident::with_dummy_span)
1048 ).map(|i| self.new_ast_path_segment(i)).collect::<Vec<_>>();
1050 let path = ast::Path {
1055 let parent_scope = &ParentScope::module(self.graph_root);
1056 let res = match self.resolve_ast_path(&path, ns, parent_scope) {
1058 Err((span, error)) => {
1059 self.report_error(span, error);
1066 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1067 self.partial_res_map.get(&id).cloned()
1070 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1071 self.import_res_map.get(&id).cloned().unwrap_or_default()
1074 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1075 self.label_res_map.get(&id).cloned()
1078 fn definitions(&mut self) -> &mut Definitions {
1079 &mut self.definitions
1082 fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1083 &mut self.lint_buffer
1086 fn next_node_id(&mut self) -> NodeId {
1091 impl<'a> Resolver<'a> {
1092 pub fn new(session: &'a Session,
1095 metadata_loader: &'a MetadataLoaderDyn,
1096 arenas: &'a ResolverArenas<'a>)
1098 let root_def_id = DefId::local(CRATE_DEF_INDEX);
1099 let root_module_kind = ModuleKind::Def(
1104 let graph_root = arenas.alloc_module(ModuleData {
1105 no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude),
1106 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1108 let empty_module_kind = ModuleKind::Def(
1113 let empty_module = arenas.alloc_module(ModuleData {
1114 no_implicit_prelude: true,
1123 let mut module_map = FxHashMap::default();
1124 module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1126 let mut definitions = Definitions::default();
1127 definitions.create_root_def(crate_name, session.local_crate_disambiguator());
1129 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> =
1130 session.opts.externs.iter().map(|kv| (Ident::from_str(kv.0), Default::default()))
1133 if !attr::contains_name(&krate.attrs, sym::no_core) {
1134 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1135 if !attr::contains_name(&krate.attrs, sym::no_std) {
1136 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1137 if session.rust_2018() {
1138 extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default());
1143 let (registered_attrs, registered_tools) =
1144 macros::registered_attrs_and_tools(session, &krate.attrs);
1146 let mut invocation_parent_scopes = FxHashMap::default();
1147 invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root));
1149 let mut macro_defs = FxHashMap::default();
1150 macro_defs.insert(ExpnId::root(), root_def_id);
1152 let features = session.features_untracked();
1153 let non_macro_attr =
1154 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1161 // The outermost module has def ID 0; this is not reflected in the
1167 has_self: FxHashSet::default(),
1168 field_names: FxHashMap::default(),
1170 determined_imports: Vec::new(),
1171 indeterminate_imports: Vec::new(),
1173 last_import_segment: false,
1174 blacklisted_binding: None,
1176 primitive_type_table: PrimitiveTypeTable::new(),
1178 partial_res_map: Default::default(),
1179 import_res_map: Default::default(),
1180 label_res_map: Default::default(),
1181 extern_crate_map: Default::default(),
1182 export_map: FxHashMap::default(),
1183 trait_map: Default::default(),
1184 underscore_disambiguator: 0,
1187 block_map: Default::default(),
1188 extern_module_map: FxHashMap::default(),
1189 binding_parent_modules: FxHashMap::default(),
1190 ast_transform_scopes: FxHashMap::default(),
1192 glob_map: Default::default(),
1194 used_imports: FxHashSet::default(),
1195 maybe_unused_trait_imports: Default::default(),
1196 maybe_unused_extern_crates: Vec::new(),
1198 privacy_errors: Vec::new(),
1199 ambiguity_errors: Vec::new(),
1200 use_injections: Vec::new(),
1201 macro_expanded_macro_export_errors: BTreeSet::new(),
1204 dummy_binding: arenas.alloc_name_binding(NameBinding {
1205 kind: NameBindingKind::Res(Res::Err, false),
1207 expansion: ExpnId::root(),
1209 vis: ty::Visibility::Public,
1212 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1213 macro_names: FxHashSet::default(),
1214 builtin_macros: Default::default(),
1217 macro_use_prelude: FxHashMap::default(),
1218 all_macros: FxHashMap::default(),
1219 macro_map: FxHashMap::default(),
1220 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1221 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1222 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1223 invocation_parent_scopes,
1224 output_legacy_scopes: Default::default(),
1225 helper_attrs: Default::default(),
1227 local_macro_def_scopes: FxHashMap::default(),
1228 name_already_seen: FxHashMap::default(),
1229 potentially_unused_imports: Vec::new(),
1230 struct_constructors: Default::default(),
1231 unused_macros: Default::default(),
1232 proc_macro_stubs: Default::default(),
1233 single_segment_macro_resolutions: Default::default(),
1234 multi_segment_macro_resolutions: Default::default(),
1235 builtin_attrs: Default::default(),
1236 containers_deriving_copy: Default::default(),
1238 features.declared_lib_features.iter().map(|(feat, ..)| *feat)
1239 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1241 variant_vis: Default::default(),
1242 lint_buffer: lint::LintBuffer::default(),
1243 next_node_id: NodeId::from_u32(1),
1247 pub fn next_node_id(&mut self) -> NodeId {
1248 let next = self.next_node_id.as_usize()
1250 .expect("input too large; ran out of NodeIds");
1251 self.next_node_id = ast::NodeId::from_usize(next);
1255 pub fn lint_buffer(&mut self) -> &mut lint::LintBuffer {
1256 &mut self.lint_buffer
1259 pub fn arenas() -> ResolverArenas<'a> {
1263 pub fn into_outputs(self) -> ResolverOutputs {
1265 definitions: self.definitions,
1266 cstore: Box::new(self.crate_loader.into_cstore()),
1267 extern_crate_map: self.extern_crate_map,
1268 export_map: self.export_map,
1269 trait_map: self.trait_map,
1270 glob_map: self.glob_map,
1271 maybe_unused_trait_imports: self.maybe_unused_trait_imports,
1272 maybe_unused_extern_crates: self.maybe_unused_extern_crates,
1273 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1274 (ident.name, entry.introduced_by_item)
1279 pub fn clone_outputs(&self) -> ResolverOutputs {
1281 definitions: self.definitions.clone(),
1282 cstore: Box::new(self.cstore().clone()),
1283 extern_crate_map: self.extern_crate_map.clone(),
1284 export_map: self.export_map.clone(),
1285 trait_map: self.trait_map.clone(),
1286 glob_map: self.glob_map.clone(),
1287 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1288 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1289 extern_prelude: self.extern_prelude.iter().map(|(ident, entry)| {
1290 (ident.name, entry.introduced_by_item)
1295 pub fn cstore(&self) -> &CStore {
1296 self.crate_loader.cstore()
1299 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1300 self.non_macro_attrs[mark_used as usize].clone()
1303 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1305 MacroKind::Bang => self.dummy_ext_bang.clone(),
1306 MacroKind::Derive => self.dummy_ext_derive.clone(),
1307 MacroKind::Attr => self.non_macro_attr(true),
1311 /// Runs the function on each namespace.
1312 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1318 fn is_builtin_macro(&mut self, res: Res) -> bool {
1319 self.get_macro(res).map_or(false, |ext| ext.is_builtin)
1322 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1324 match self.macro_defs.get(&ctxt.outer_expn()) {
1325 Some(&def_id) => return def_id,
1326 None => ctxt.remove_mark(),
1331 /// Entry point to crate resolution.
1332 pub fn resolve_crate(&mut self, krate: &Crate) {
1334 self.session.prof.generic_activity("resolve_crate");
1336 ImportResolver { r: self }.finalize_imports();
1337 self.finalize_macro_resolutions();
1339 self.late_resolve_crate(krate);
1341 self.check_unused(krate);
1342 self.report_errors(krate);
1343 self.crate_loader.postprocess(krate);
1350 normal_ancestor_id: DefId,
1354 let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span);
1355 self.arenas.alloc_module(module)
1358 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1359 let ident = ident.modern();
1360 let disambiguator = if ident.name == kw::Underscore {
1361 self.underscore_disambiguator += 1;
1362 self.underscore_disambiguator
1366 BindingKey { ident, ns, disambiguator }
1369 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1370 if module.populate_on_access.get() {
1371 module.populate_on_access.set(false);
1372 self.build_reduced_graph_external(module);
1374 &module.lazy_resolutions
1377 fn resolution(&mut self, module: Module<'a>, key: BindingKey)
1378 -> &'a RefCell<NameResolution<'a>> {
1379 *self.resolutions(module).borrow_mut().entry(key)
1380 .or_insert_with(|| self.arenas.alloc_name_resolution())
1383 fn record_use(&mut self, ident: Ident, ns: Namespace,
1384 used_binding: &'a NameBinding<'a>, is_lexical_scope: bool) {
1385 if let Some((b2, kind)) = used_binding.ambiguity {
1386 self.ambiguity_errors.push(AmbiguityError {
1387 kind, ident, b1: used_binding, b2,
1388 misc1: AmbiguityErrorMisc::None,
1389 misc2: AmbiguityErrorMisc::None,
1392 if let NameBindingKind::Import { directive, binding, ref used } = used_binding.kind {
1393 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1394 // but not introduce it, as used if they are accessed from lexical scope.
1395 if is_lexical_scope {
1396 if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
1397 if let Some(crate_item) = entry.extern_crate_item {
1398 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1405 directive.used.set(true);
1406 self.used_imports.insert((directive.id, ns));
1407 self.add_to_glob_map(&directive, ident);
1408 self.record_use(ident, ns, binding, false);
1413 fn add_to_glob_map(&mut self, directive: &ImportDirective<'_>, ident: Ident) {
1414 if directive.is_glob() {
1415 self.glob_map.entry(directive.id).or_default().insert(ident.name);
1419 /// A generic scope visitor.
1420 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1421 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1424 scope_set: ScopeSet,
1425 parent_scope: &ParentScope<'a>,
1427 mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>,
1429 // General principles:
1430 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1431 // built into the language or standard library. This way we can add new names into the
1432 // language or standard library without breaking user code.
1433 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1434 // Places to search (in order of decreasing priority):
1436 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1437 // (open set, not controlled).
1438 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1439 // (open, not controlled).
1440 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1441 // 4. Tool modules (closed, controlled right now, but not in the future).
1442 // 5. Standard library prelude (de-facto closed, controlled).
1443 // 6. Language prelude (closed, controlled).
1445 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1446 // (open set, not controlled).
1447 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1448 // (open, not controlled).
1449 // 3. Standard library prelude (de-facto closed, controlled).
1451 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1452 // are currently reported as errors. They should be higher in priority than preludes
1453 // and probably even names in modules according to the "general principles" above. They
1454 // also should be subject to restricted shadowing because are effectively produced by
1455 // derives (you need to resolve the derive first to add helpers into scope), but they
1456 // should be available before the derive is expanded for compatibility.
1457 // It's mess in general, so we are being conservative for now.
1458 // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher
1459 // priority than prelude macros, but create ambiguities with macros in modules.
1460 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1461 // (open, not controlled). Have higher priority than prelude macros, but create
1462 // ambiguities with `macro_rules`.
1463 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1464 // 4a. User-defined prelude from macro-use
1465 // (open, the open part is from macro expansions, not controlled).
1466 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1467 // 4c. Standard library prelude (de-facto closed, controlled).
1468 // 6. Language prelude: builtin attributes (closed, controlled).
1469 // 4-6. Legacy plugin helpers (open, not controlled). Similar to derive helpers,
1470 // but introduced by legacy plugins using `register_attribute`. Priority is somewhere
1471 // in prelude, not sure where exactly (creates ambiguities with any other prelude names).
1473 let rust_2015 = ident.span.rust_2015();
1474 let (ns, macro_kind, is_absolute_path) = match scope_set {
1475 ScopeSet::All(ns, _) => (ns, None, false),
1476 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1477 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1479 // Jump out of trait or enum modules, they do not act as scopes.
1480 let module = parent_scope.module.nearest_item_scope();
1481 let mut scope = match ns {
1482 _ if is_absolute_path => Scope::CrateRoot,
1483 TypeNS | ValueNS => Scope::Module(module),
1484 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1486 let mut ident = ident.modern();
1487 let mut use_prelude = !module.no_implicit_prelude;
1490 let visit = match scope {
1491 // Derive helpers are not in scope when resolving derives in the same container.
1492 Scope::DeriveHelpers(expn_id) =>
1493 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive)),
1494 Scope::DeriveHelpersCompat => true,
1495 Scope::MacroRules(..) => true,
1496 Scope::CrateRoot => true,
1497 Scope::Module(..) => true,
1498 Scope::RegisteredAttrs => use_prelude,
1499 Scope::MacroUsePrelude => use_prelude || rust_2015,
1500 Scope::BuiltinAttrs => true,
1501 Scope::LegacyPluginHelpers => use_prelude || rust_2015,
1502 Scope::ExternPrelude => use_prelude || is_absolute_path,
1503 Scope::ToolPrelude => use_prelude,
1504 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1505 Scope::BuiltinTypes => true,
1509 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) {
1510 return break_result;
1514 scope = match scope {
1515 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1516 // Derive helpers are not visible to code generated by bang or derive macros.
1517 let expn_data = expn_id.expn_data();
1518 match expn_data.kind {
1520 ExpnKind::Macro(MacroKind::Bang, _) |
1521 ExpnKind::Macro(MacroKind::Derive, _) => Scope::DeriveHelpersCompat,
1522 _ => Scope::DeriveHelpers(expn_data.parent),
1525 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1526 Scope::DeriveHelpersCompat =>
1527 Scope::MacroRules(parent_scope.legacy),
1528 Scope::MacroRules(legacy_scope) => match legacy_scope {
1529 LegacyScope::Binding(binding) => Scope::MacroRules(
1530 binding.parent_legacy_scope
1532 LegacyScope::Invocation(invoc_id) => Scope::MacroRules(
1533 self.output_legacy_scopes.get(&invoc_id).cloned()
1534 .unwrap_or(self.invocation_parent_scopes[&invoc_id].legacy)
1536 LegacyScope::Empty => Scope::Module(module),
1538 Scope::CrateRoot => match ns {
1540 ident.span.adjust(ExpnId::root());
1541 Scope::ExternPrelude
1543 ValueNS | MacroNS => break,
1545 Scope::Module(module) => {
1546 use_prelude = !module.no_implicit_prelude;
1547 match self.hygienic_lexical_parent(module, &mut ident.span) {
1548 Some(parent_module) => Scope::Module(parent_module),
1550 ident.span.adjust(ExpnId::root());
1552 TypeNS => Scope::ExternPrelude,
1553 ValueNS => Scope::StdLibPrelude,
1554 MacroNS => Scope::RegisteredAttrs,
1559 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1560 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1561 Scope::BuiltinAttrs => Scope::LegacyPluginHelpers,
1562 Scope::LegacyPluginHelpers => break, // nowhere else to search
1563 Scope::ExternPrelude if is_absolute_path => break,
1564 Scope::ExternPrelude => Scope::ToolPrelude,
1565 Scope::ToolPrelude => Scope::StdLibPrelude,
1566 Scope::StdLibPrelude => match ns {
1567 TypeNS => Scope::BuiltinTypes,
1568 ValueNS => break, // nowhere else to search
1569 MacroNS => Scope::BuiltinAttrs,
1571 Scope::BuiltinTypes => break, // nowhere else to search
1578 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1579 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1580 /// `ident` in the first scope that defines it (or None if no scopes define it).
1582 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1583 /// the items are defined in the block. For example,
1586 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1589 /// g(); // This resolves to the local variable `g` since it shadows the item.
1593 /// Invariant: This must only be called during main resolution, not during
1594 /// import resolution.
1595 fn resolve_ident_in_lexical_scope(&mut self,
1598 parent_scope: &ParentScope<'a>,
1599 record_used_id: Option<NodeId>,
1602 -> Option<LexicalScopeBinding<'a>> {
1603 assert!(ns == TypeNS || ns == ValueNS);
1604 if ident.name == kw::Invalid {
1605 return Some(LexicalScopeBinding::Res(Res::Err));
1607 let (general_span, modern_span) = if ident.name == kw::SelfUpper {
1608 // FIXME(jseyfried) improve `Self` hygiene
1609 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1610 (empty_span, empty_span)
1611 } else if ns == TypeNS {
1612 let modern_span = ident.span.modern();
1613 (modern_span, modern_span)
1615 (ident.span.modern_and_legacy(), ident.span.modern())
1617 ident.span = general_span;
1618 let modern_ident = Ident { span: modern_span, ..ident };
1620 // Walk backwards up the ribs in scope.
1621 let record_used = record_used_id.is_some();
1622 let mut module = self.graph_root;
1623 for i in (0 .. ribs.len()).rev() {
1624 debug!("walk rib\n{:?}", ribs[i].bindings);
1625 // Use the rib kind to determine whether we are resolving parameters
1626 // (modern hygiene) or local variables (legacy hygiene).
1627 let rib_ident = if ribs[i].kind.contains_params() {
1632 if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() {
1633 // The ident resolves to a type parameter or local variable.
1634 return Some(LexicalScopeBinding::Res(
1635 self.validate_res_from_ribs(i, rib_ident, res, record_used, path_span, ribs),
1639 module = match ribs[i].kind {
1640 ModuleRibKind(module) => module,
1641 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1642 // If an invocation of this macro created `ident`, give up on `ident`
1643 // and switch to `ident`'s source from the macro definition.
1644 ident.span.remove_mark();
1651 let item = self.resolve_ident_in_module_unadjusted(
1652 ModuleOrUniformRoot::Module(module),
1659 if let Ok(binding) = item {
1660 // The ident resolves to an item.
1661 return Some(LexicalScopeBinding::Item(binding));
1665 ModuleKind::Block(..) => {}, // We can see through blocks
1670 ident = modern_ident;
1671 let mut poisoned = None;
1673 let opt_module = if let Some(node_id) = record_used_id {
1674 self.hygienic_lexical_parent_with_compatibility_fallback(module, &mut ident.span,
1675 node_id, &mut poisoned)
1677 self.hygienic_lexical_parent(module, &mut ident.span)
1679 module = unwrap_or!(opt_module, break);
1680 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1681 let result = self.resolve_ident_in_module_unadjusted(
1682 ModuleOrUniformRoot::Module(module),
1685 adjusted_parent_scope,
1692 if let Some(node_id) = poisoned {
1693 self.lint_buffer.buffer_lint_with_diagnostic(
1694 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1695 node_id, ident.span,
1696 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1697 lint::builtin::BuiltinLintDiagnostics::
1698 ProcMacroDeriveResolutionFallback(ident.span),
1701 return Some(LexicalScopeBinding::Item(binding))
1703 Err(Determined) => continue,
1704 Err(Undetermined) =>
1705 span_bug!(ident.span, "undetermined resolution during main resolution pass"),
1709 if !module.no_implicit_prelude {
1710 ident.span.adjust(ExpnId::root());
1712 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1713 return Some(LexicalScopeBinding::Item(binding));
1715 if let Some(ident) = self.registered_tools.get(&ident) {
1716 let binding = (Res::ToolMod, ty::Visibility::Public,
1717 ident.span, ExpnId::root()).to_name_binding(self.arenas);
1718 return Some(LexicalScopeBinding::Item(binding));
1721 if let Some(prelude) = self.prelude {
1722 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1723 ModuleOrUniformRoot::Module(prelude),
1730 return Some(LexicalScopeBinding::Item(binding));
1738 fn hygienic_lexical_parent(&mut self, module: Module<'a>, span: &mut Span)
1739 -> Option<Module<'a>> {
1740 if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1741 return Some(self.macro_def_scope(span.remove_mark()));
1744 if let ModuleKind::Block(..) = module.kind {
1745 return Some(module.parent.unwrap().nearest_item_scope());
1751 fn hygienic_lexical_parent_with_compatibility_fallback(&mut self, module: Module<'a>,
1752 span: &mut Span, node_id: NodeId,
1753 poisoned: &mut Option<NodeId>)
1754 -> Option<Module<'a>> {
1755 if let module @ Some(..) = self.hygienic_lexical_parent(module, span) {
1759 // We need to support the next case under a deprecation warning
1762 // ---- begin: this comes from a proc macro derive
1763 // mod implementation_details {
1764 // // Note that `MyStruct` is not in scope here.
1765 // impl SomeTrait for MyStruct { ... }
1769 // So we have to fall back to the module's parent during lexical resolution in this case.
1770 if let Some(parent) = module.parent {
1771 // Inner module is inside the macro, parent module is outside of the macro.
1772 if module.expansion != parent.expansion &&
1773 module.expansion.is_descendant_of(parent.expansion) {
1774 // The macro is a proc macro derive
1775 if let Some(&def_id) = self.macro_defs.get(&module.expansion) {
1776 if let Some(ext) = self.get_macro_by_def_id(def_id) {
1777 if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive {
1778 if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) {
1779 *poisoned = Some(node_id);
1780 return module.parent;
1791 fn resolve_ident_in_module(
1793 module: ModuleOrUniformRoot<'a>,
1796 parent_scope: &ParentScope<'a>,
1799 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1800 self.resolve_ident_in_module_ext(
1801 module, ident, ns, parent_scope, record_used, path_span
1802 ).map_err(|(determinacy, _)| determinacy)
1805 fn resolve_ident_in_module_ext(
1807 module: ModuleOrUniformRoot<'a>,
1810 parent_scope: &ParentScope<'a>,
1813 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
1814 let tmp_parent_scope;
1815 let mut adjusted_parent_scope = parent_scope;
1817 ModuleOrUniformRoot::Module(m) => {
1818 if let Some(def) = ident.span.modernize_and_adjust(m.expansion) {
1820 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
1821 adjusted_parent_scope = &tmp_parent_scope;
1824 ModuleOrUniformRoot::ExternPrelude => {
1825 ident.span.modernize_and_adjust(ExpnId::root());
1827 ModuleOrUniformRoot::CrateRootAndExternPrelude |
1828 ModuleOrUniformRoot::CurrentScope => {
1832 let result = self.resolve_ident_in_module_unadjusted_ext(
1833 module, ident, ns, adjusted_parent_scope, false, record_used, path_span,
1838 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
1839 let mut ctxt = ident.span.ctxt();
1840 let mark = if ident.name == kw::DollarCrate {
1841 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
1842 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
1843 // as described in `SyntaxContext::apply_mark`, so we ignore prepended modern marks.
1844 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
1845 // definitions actually produced by `macro` and `macro` definitions produced by
1846 // `macro_rules!`, but at least such configurations are not stable yet.
1847 ctxt = ctxt.modern_and_legacy();
1848 let mut iter = ctxt.marks().into_iter().rev().peekable();
1849 let mut result = None;
1850 // Find the last modern mark from the end if it exists.
1851 while let Some(&(mark, transparency)) = iter.peek() {
1852 if transparency == Transparency::Opaque {
1853 result = Some(mark);
1859 // Then find the last legacy mark from the end if it exists.
1860 for (mark, transparency) in iter {
1861 if transparency == Transparency::SemiTransparent {
1862 result = Some(mark);
1869 ctxt = ctxt.modern();
1870 ctxt.adjust(ExpnId::root())
1872 let module = match mark {
1873 Some(def) => self.macro_def_scope(def),
1874 None => return self.graph_root,
1876 self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
1879 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
1880 let mut module = self.get_module(module.normal_ancestor_id);
1881 while module.span.ctxt().modern() != *ctxt {
1882 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
1883 module = self.get_module(parent.normal_ancestor_id);
1891 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1892 parent_scope: &ParentScope<'a>,
1895 crate_lint: CrateLint,
1896 ) -> PathResult<'a> {
1897 self.resolve_path_with_ribs(
1898 path, opt_ns, parent_scope, record_used, path_span, crate_lint, None
1902 fn resolve_path_with_ribs(
1905 opt_ns: Option<Namespace>, // `None` indicates a module path in import
1906 parent_scope: &ParentScope<'a>,
1909 crate_lint: CrateLint,
1910 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
1911 ) -> PathResult<'a> {
1912 let mut module = None;
1913 let mut allow_super = true;
1914 let mut second_binding = None;
1917 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
1918 path_span={:?}, crate_lint={:?})",
1926 for (i, &Segment { ident, id }) in path.iter().enumerate() {
1927 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
1928 let record_segment_res = |this: &mut Self, res| {
1930 if let Some(id) = id {
1931 if !this.partial_res_map.contains_key(&id) {
1932 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
1933 this.record_partial_res(id, PartialRes::new(res));
1939 let is_last = i == path.len() - 1;
1940 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
1941 let name = ident.name;
1943 allow_super &= ns == TypeNS &&
1944 (name == kw::SelfLower ||
1948 if allow_super && name == kw::Super {
1949 let mut ctxt = ident.span.ctxt().modern();
1950 let self_module = match i {
1951 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
1953 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
1957 if let Some(self_module) = self_module {
1958 if let Some(parent) = self_module.parent {
1959 module = Some(ModuleOrUniformRoot::Module(
1960 self.resolve_self(&mut ctxt, parent)));
1964 let msg = "there are too many initial `super`s.".to_string();
1965 return PathResult::Failed {
1969 is_error_from_last_segment: false,
1973 if name == kw::SelfLower {
1974 let mut ctxt = ident.span.ctxt().modern();
1975 module = Some(ModuleOrUniformRoot::Module(
1976 self.resolve_self(&mut ctxt, parent_scope.module)));
1979 if name == kw::PathRoot && ident.span.rust_2018() {
1980 module = Some(ModuleOrUniformRoot::ExternPrelude);
1983 if name == kw::PathRoot &&
1984 ident.span.rust_2015() && self.session.rust_2018() {
1985 // `::a::b` from 2015 macro on 2018 global edition
1986 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
1989 if name == kw::PathRoot ||
1990 name == kw::Crate ||
1991 name == kw::DollarCrate {
1992 // `::a::b`, `crate::a::b` or `$crate::a::b`
1993 module = Some(ModuleOrUniformRoot::Module(
1994 self.resolve_crate_root(ident)));
2000 // Report special messages for path segment keywords in wrong positions.
2001 if ident.is_path_segment_keyword() && i != 0 {
2002 let name_str = if name == kw::PathRoot {
2003 "crate root".to_string()
2005 format!("`{}`", name)
2007 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2008 format!("global paths cannot start with {}", name_str)
2010 format!("{} in paths can only be used in start position", name_str)
2012 return PathResult::Failed {
2016 is_error_from_last_segment: false,
2020 let binding = if let Some(module) = module {
2021 self.resolve_ident_in_module(
2022 module, ident, ns, parent_scope, record_used, path_span
2024 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2025 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2026 self.early_resolve_ident_in_lexical_scope(ident, scopes, parent_scope, record_used,
2027 record_used, path_span)
2029 let record_used_id =
2030 if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };
2031 match self.resolve_ident_in_lexical_scope(
2032 ident, ns, parent_scope, record_used_id, path_span, &ribs.unwrap()[ns]
2034 // we found a locally-imported or available item/module
2035 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2036 // we found a local variable or type param
2037 Some(LexicalScopeBinding::Res(res))
2038 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2039 record_segment_res(self, res);
2040 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2044 _ => Err(Determinacy::determined(record_used)),
2051 second_binding = Some(binding);
2053 let res = binding.res();
2054 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2055 if let Some(next_module) = binding.module() {
2056 module = Some(ModuleOrUniformRoot::Module(next_module));
2057 record_segment_res(self, res);
2058 } else if res == Res::ToolMod && i + 1 != path.len() {
2059 if binding.is_import() {
2060 self.session.struct_span_err(
2061 ident.span, "cannot use a tool module through an import"
2063 binding.span, "the tool module imported here"
2066 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2067 return PathResult::NonModule(PartialRes::new(res));
2068 } else if res == Res::Err {
2069 return PathResult::NonModule(PartialRes::new(Res::Err));
2070 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2071 self.lint_if_path_starts_with_module(
2077 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2078 res, path.len() - i - 1
2081 let label = format!(
2082 "`{}` is {} {}, not a module",
2088 return PathResult::Failed {
2092 is_error_from_last_segment: is_last,
2096 Err(Undetermined) => return PathResult::Indeterminate,
2097 Err(Determined) => {
2098 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2099 if opt_ns.is_some() && !module.is_normal() {
2100 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2101 module.res().unwrap(), path.len() - i
2105 let module_res = match module {
2106 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2109 let (label, suggestion) = if module_res == self.graph_root.res() {
2110 let is_mod = |res| {
2111 match res { Res::Def(DefKind::Mod, _) => true, _ => false }
2113 let mut candidates =
2114 self.lookup_import_candidates(ident, TypeNS, is_mod);
2115 candidates.sort_by_cached_key(|c| {
2116 (c.path.segments.len(), pprust::path_to_string(&c.path))
2118 if let Some(candidate) = candidates.get(0) {
2120 String::from("unresolved import"),
2122 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2123 String::from("a similar path exists"),
2124 Applicability::MaybeIncorrect,
2127 } else if !ident.is_reserved() {
2128 (format!("maybe a missing crate `{}`?", ident), None)
2130 // the parser will already have complained about the keyword being used
2131 return PathResult::NonModule(PartialRes::new(Res::Err));
2134 (format!("use of undeclared type or module `{}`", ident), None)
2136 (format!("could not find `{}` in `{}`", ident, path[i - 1].ident), None)
2138 return PathResult::Failed {
2142 is_error_from_last_segment: is_last,
2148 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2150 PathResult::Module(match module {
2151 Some(module) => module,
2152 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2153 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2157 fn lint_if_path_starts_with_module(
2159 crate_lint: CrateLint,
2162 second_binding: Option<&NameBinding<'_>>,
2164 let (diag_id, diag_span) = match crate_lint {
2165 CrateLint::No => return,
2166 CrateLint::SimplePath(id) => (id, path_span),
2167 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2168 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2171 let first_name = match path.get(0) {
2172 // In the 2018 edition this lint is a hard error, so nothing to do
2173 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2177 // We're only interested in `use` paths which should start with
2178 // `{{root}}` currently.
2179 if first_name != kw::PathRoot {
2184 // If this import looks like `crate::...` it's already good
2185 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2186 // Otherwise go below to see if it's an extern crate
2188 // If the path has length one (and it's `PathRoot` most likely)
2189 // then we don't know whether we're gonna be importing a crate or an
2190 // item in our crate. Defer this lint to elsewhere
2194 // If the first element of our path was actually resolved to an
2195 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2196 // warning, this looks all good!
2197 if let Some(binding) = second_binding {
2198 if let NameBindingKind::Import { directive: d, .. } = binding.kind {
2199 // Careful: we still want to rewrite paths from
2200 // renamed extern crates.
2201 if let ImportDirectiveSubclass::ExternCrate { source: None, .. } = d.subclass {
2207 let diag = lint::builtin::BuiltinLintDiagnostics
2208 ::AbsPathWithModule(diag_span);
2209 self.lint_buffer.buffer_lint_with_diagnostic(
2210 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2212 "absolute paths must start with `self`, `super`, \
2213 `crate`, or an external crate name in the 2018 edition",
2217 // Validate a local resolution (from ribs).
2218 fn validate_res_from_ribs(
2225 all_ribs: &[Rib<'a>],
2227 debug!("validate_res_from_ribs({:?})", res);
2228 let ribs = &all_ribs[rib_index + 1..];
2230 // An invalid forward use of a type parameter from a previous default.
2231 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2233 let res_error = if rib_ident.name == kw::SelfUpper {
2234 ResolutionError::SelfInTyParamDefault
2236 ResolutionError::ForwardDeclaredTyParam
2238 self.report_error(span, res_error);
2240 assert_eq!(res, Res::Err);
2246 use ResolutionError::*;
2247 let mut res_err = None;
2251 NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2252 ForwardTyParamBanRibKind => {
2253 // Nothing to do. Continue.
2255 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2256 // This was an attempt to access an upvar inside a
2257 // named function item. This is not allowed, so we
2260 // We don't immediately trigger a resolve error, because
2261 // we want certain other resolution errors (namely those
2262 // emitted for `ConstantItemRibKind` below) to take
2264 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2267 ConstantItemRibKind => {
2268 // Still doesn't deal with upvars
2270 self.report_error(span, AttemptToUseNonConstantValueInConstant);
2276 if let Some(res_err) = res_err {
2277 self.report_error(span, res_err);
2281 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2283 let has_generic_params = match rib.kind {
2284 NormalRibKind | AssocItemRibKind |
2285 ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2286 ConstantItemRibKind => {
2287 // Nothing to do. Continue.
2290 // This was an attempt to use a type parameter outside its scope.
2291 ItemRibKind(has_generic_params) => has_generic_params,
2292 FnItemRibKind => HasGenericParams::Yes,
2296 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2297 res, has_generic_params));
2302 Res::Def(DefKind::ConstParam, _) => {
2303 let mut ribs = ribs.iter().peekable();
2304 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2305 // When declaring const parameters inside function signatures, the first rib
2306 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2307 // (spuriously) conflicting with the const param.
2311 let has_generic_params = match rib.kind {
2312 ItemRibKind(has_generic_params) => has_generic_params,
2313 FnItemRibKind => HasGenericParams::Yes,
2317 // This was an attempt to use a const parameter outside its scope.
2319 self.report_error(span, ResolutionError::GenericParamsFromOuterFunction(
2320 res, has_generic_params));
2330 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2331 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2332 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2333 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2337 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2338 vis.is_accessible_from(module.normal_ancestor_id, self)
2341 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2342 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2343 if !ptr::eq(module, old_module) {
2344 span_bug!(binding.span, "parent module is reset for binding");
2349 fn disambiguate_legacy_vs_modern(
2351 legacy: &'a NameBinding<'a>,
2352 modern: &'a NameBinding<'a>,
2354 // Some non-controversial subset of ambiguities "modern macro name" vs "macro_rules"
2355 // is disambiguated to mitigate regressions from macro modularization.
2356 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2357 match (self.binding_parent_modules.get(&PtrKey(legacy)),
2358 self.binding_parent_modules.get(&PtrKey(modern))) {
2359 (Some(legacy), Some(modern)) =>
2360 legacy.normal_ancestor_id == modern.normal_ancestor_id &&
2361 modern.is_ancestor_of(legacy),
2366 fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
2368 if b.span.is_dummy() {
2369 let add_built_in = match b.res() {
2370 // These already contain the "built-in" prefix or look bad with it.
2371 Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod => false,
2374 let (built_in, from) = if from_prelude {
2375 ("", " from prelude")
2376 } else if b.is_extern_crate() && !b.is_import() &&
2377 self.session.opts.externs.get(&ident.as_str()).is_some() {
2378 ("", " passed with `--extern`")
2379 } else if add_built_in {
2385 let article = if built_in.is_empty() { res.article() } else { "a" };
2386 format!("{a}{built_in} {thing}{from}",
2387 a = article, thing = res.descr(), built_in = built_in, from = from)
2389 let introduced = if b.is_import() { "imported" } else { "defined" };
2390 format!("the {thing} {introduced} here",
2391 thing = res.descr(), introduced = introduced)
2395 fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
2396 let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
2397 let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
2398 // We have to print the span-less alternative first, otherwise formatting looks bad.
2399 (b2, b1, misc2, misc1, true)
2401 (b1, b2, misc1, misc2, false)
2404 let mut err = struct_span_err!(self.session, ident.span, E0659,
2405 "`{ident}` is ambiguous ({why})",
2406 ident = ident, why = kind.descr());
2407 err.span_label(ident.span, "ambiguous name");
2409 let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
2410 let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
2411 let note_msg = format!("`{ident}` could{also} refer to {what}",
2412 ident = ident, also = also, what = what);
2414 let thing = b.res().descr();
2415 let mut help_msgs = Vec::new();
2416 if b.is_glob_import() && (kind == AmbiguityKind::GlobVsGlob ||
2417 kind == AmbiguityKind::GlobVsExpanded ||
2418 kind == AmbiguityKind::GlobVsOuter &&
2419 swapped != also.is_empty()) {
2420 help_msgs.push(format!("consider adding an explicit import of \
2421 `{ident}` to disambiguate", ident = ident))
2423 if b.is_extern_crate() && ident.span.rust_2018() {
2424 help_msgs.push(format!(
2425 "use `::{ident}` to refer to this {thing} unambiguously",
2426 ident = ident, thing = thing,
2429 if misc == AmbiguityErrorMisc::SuggestCrate {
2430 help_msgs.push(format!(
2431 "use `crate::{ident}` to refer to this {thing} unambiguously",
2432 ident = ident, thing = thing,
2434 } else if misc == AmbiguityErrorMisc::SuggestSelf {
2435 help_msgs.push(format!(
2436 "use `self::{ident}` to refer to this {thing} unambiguously",
2437 ident = ident, thing = thing,
2441 err.span_note(b.span, ¬e_msg);
2442 for (i, help_msg) in help_msgs.iter().enumerate() {
2443 let or = if i == 0 { "" } else { "or " };
2444 err.help(&format!("{}{}", or, help_msg));
2448 could_refer_to(b1, misc1, "");
2449 could_refer_to(b2, misc2, " also");
2453 fn report_errors(&mut self, krate: &Crate) {
2454 self.report_with_use_injections(krate);
2456 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2457 let msg = "macro-expanded `macro_export` macros from the current crate \
2458 cannot be referred to by absolute paths";
2459 self.lint_buffer.buffer_lint_with_diagnostic(
2460 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2461 CRATE_NODE_ID, span_use, msg,
2462 lint::builtin::BuiltinLintDiagnostics::
2463 MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2467 for ambiguity_error in &self.ambiguity_errors {
2468 self.report_ambiguity_error(ambiguity_error);
2471 let mut reported_spans = FxHashSet::default();
2472 for &PrivacyError(dedup_span, ident, binding) in &self.privacy_errors {
2473 if reported_spans.insert(dedup_span) {
2474 let session = &self.session;
2475 let mk_struct_span_error = |is_constructor| {
2480 "{}{} `{}` is private",
2481 binding.res().descr(),
2482 if is_constructor { " constructor"} else { "" },
2487 let mut err = if let NameBindingKind::Res(
2488 Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id), _
2490 let def_id = (&*self).parent(ctor_def_id).expect("no parent for a constructor");
2491 if let Some(fields) = self.field_names.get(&def_id) {
2492 let mut err = mk_struct_span_error(true);
2493 let first_field = fields.first().expect("empty field list in the map");
2495 fields.iter().fold(first_field.span, |acc, field| acc.to(field.span)),
2496 "a constructor is private if any of the fields is private",
2500 mk_struct_span_error(false)
2503 mk_struct_span_error(false)
2511 fn report_with_use_injections(&mut self, krate: &Crate) {
2512 for UseError { mut err, candidates, node_id, better } in self.use_injections.drain(..) {
2513 let (span, found_use) = UsePlacementFinder::check(krate, node_id);
2514 if !candidates.is_empty() {
2515 diagnostics::show_candidates(&mut err, span, &candidates, better, found_use);
2521 fn report_conflict<'b>(&mut self,
2525 new_binding: &NameBinding<'b>,
2526 old_binding: &NameBinding<'b>) {
2527 // Error on the second of two conflicting names
2528 if old_binding.span.lo() > new_binding.span.lo() {
2529 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2532 let container = match parent.kind {
2533 ModuleKind::Def(DefKind::Mod, _, _) => "module",
2534 ModuleKind::Def(DefKind::Trait, _, _) => "trait",
2535 ModuleKind::Block(..) => "block",
2539 let old_noun = match old_binding.is_import() {
2541 false => "definition",
2544 let new_participle = match new_binding.is_import() {
2549 let (name, span) = (ident.name, self.session.source_map().def_span(new_binding.span));
2551 if let Some(s) = self.name_already_seen.get(&name) {
2557 let old_kind = match (ns, old_binding.module()) {
2558 (ValueNS, _) => "value",
2559 (MacroNS, _) => "macro",
2560 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2561 (TypeNS, Some(module)) if module.is_normal() => "module",
2562 (TypeNS, Some(module)) if module.is_trait() => "trait",
2563 (TypeNS, _) => "type",
2566 let msg = format!("the name `{}` is defined multiple times", name);
2568 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2569 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2570 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2571 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2572 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2574 _ => match (old_binding.is_import(), new_binding.is_import()) {
2575 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2576 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2577 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2581 err.note(&format!("`{}` must be defined only once in the {} namespace of this {}",
2586 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2588 self.session.source_map().def_span(old_binding.span),
2589 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2592 // See https://github.com/rust-lang/rust/issues/32354
2593 use NameBindingKind::Import;
2594 let directive = match (&new_binding.kind, &old_binding.kind) {
2595 // If there are two imports where one or both have attributes then prefer removing the
2596 // import without attributes.
2597 (Import { directive: new, .. }, Import { directive: old, .. }) if {
2598 !new_binding.span.is_dummy() && !old_binding.span.is_dummy() &&
2599 (new.has_attributes || old.has_attributes)
2601 if old.has_attributes {
2602 Some((new, new_binding.span, true))
2604 Some((old, old_binding.span, true))
2607 // Otherwise prioritize the new binding.
2608 (Import { directive, .. }, other) if !new_binding.span.is_dummy() =>
2609 Some((directive, new_binding.span, other.is_import())),
2610 (other, Import { directive, .. }) if !old_binding.span.is_dummy() =>
2611 Some((directive, old_binding.span, other.is_import())),
2615 // Check if the target of the use for both bindings is the same.
2616 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2617 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2618 let from_item = self.extern_prelude.get(&ident)
2619 .map(|entry| entry.introduced_by_item)
2621 // Only suggest removing an import if both bindings are to the same def, if both spans
2622 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2623 // been introduced by a item.
2624 let should_remove_import = duplicate && !has_dummy_span &&
2625 ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2628 Some((directive, span, true)) if should_remove_import && directive.is_nested() =>
2629 self.add_suggestion_for_duplicate_nested_use(&mut err, directive, span),
2630 Some((directive, _, true)) if should_remove_import && !directive.is_glob() => {
2631 // Simple case - remove the entire import. Due to the above match arm, this can
2632 // only be a single use so just remove it entirely.
2633 err.tool_only_span_suggestion(
2634 directive.use_span_with_attributes,
2635 "remove unnecessary import",
2637 Applicability::MaybeIncorrect,
2640 Some((directive, span, _)) =>
2641 self.add_suggestion_for_rename_of_use(&mut err, name, directive, span),
2646 self.name_already_seen.insert(name, span);
2649 /// This function adds a suggestion to change the binding name of a new import that conflicts
2650 /// with an existing import.
2652 /// ```ignore (diagnostic)
2653 /// help: you can use `as` to change the binding name of the import
2655 /// LL | use foo::bar as other_bar;
2656 /// | ^^^^^^^^^^^^^^^^^^^^^
2658 fn add_suggestion_for_rename_of_use(
2660 err: &mut DiagnosticBuilder<'_>,
2662 directive: &ImportDirective<'_>,
2665 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
2666 format!("Other{}", name)
2668 format!("other_{}", name)
2671 let mut suggestion = None;
2672 match directive.subclass {
2673 ImportDirectiveSubclass::SingleImport { type_ns_only: true, .. } =>
2674 suggestion = Some(format!("self as {}", suggested_name)),
2675 ImportDirectiveSubclass::SingleImport { source, .. } => {
2676 if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0)
2677 .map(|pos| pos as usize) {
2678 if let Ok(snippet) = self.session.source_map()
2679 .span_to_snippet(binding_span) {
2680 if pos <= snippet.len() {
2681 suggestion = Some(format!(
2685 if snippet.ends_with(";") { ";" } else { "" }
2691 ImportDirectiveSubclass::ExternCrate { source, target, .. } =>
2692 suggestion = Some(format!(
2693 "extern crate {} as {};",
2694 source.unwrap_or(target.name),
2697 _ => unreachable!(),
2700 let rename_msg = "you can use `as` to change the binding name of the import";
2701 if let Some(suggestion) = suggestion {
2702 err.span_suggestion(
2706 Applicability::MaybeIncorrect,
2709 err.span_label(binding_span, rename_msg);
2713 /// This function adds a suggestion to remove a unnecessary binding from an import that is
2714 /// nested. In the following example, this function will be invoked to remove the `a` binding
2715 /// in the second use statement:
2717 /// ```ignore (diagnostic)
2718 /// use issue_52891::a;
2719 /// use issue_52891::{d, a, e};
2722 /// The following suggestion will be added:
2724 /// ```ignore (diagnostic)
2725 /// use issue_52891::{d, a, e};
2726 /// ^-- help: remove unnecessary import
2729 /// If the nested use contains only one import then the suggestion will remove the entire
2732 /// It is expected that the directive provided is a nested import - this isn't checked by the
2733 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
2734 /// as characters expected by span manipulations won't be present.
2735 fn add_suggestion_for_duplicate_nested_use(
2737 err: &mut DiagnosticBuilder<'_>,
2738 directive: &ImportDirective<'_>,
2741 assert!(directive.is_nested());
2742 let message = "remove unnecessary import";
2744 // Two examples will be used to illustrate the span manipulations we're doing:
2746 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
2747 // `a` and `directive.use_span` is `issue_52891::{d, a, e};`.
2748 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
2749 // `a` and `directive.use_span` is `issue_52891::{d, e, a};`.
2751 let (found_closing_brace, span) = find_span_of_binding_until_next_binding(
2752 self.session, binding_span, directive.use_span,
2755 // If there was a closing brace then identify the span to remove any trailing commas from
2756 // previous imports.
2757 if found_closing_brace {
2758 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
2759 err.tool_only_span_suggestion(span, message, String::new(),
2760 Applicability::MaybeIncorrect);
2762 // Remove the entire line if we cannot extend the span back, this indicates a
2763 // `issue_52891::{self}` case.
2764 err.span_suggestion(directive.use_span_with_attributes, message, String::new(),
2765 Applicability::MaybeIncorrect);
2771 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
2774 fn extern_prelude_get(&mut self, ident: Ident, speculative: bool)
2775 -> Option<&'a NameBinding<'a>> {
2776 if ident.is_path_segment_keyword() {
2777 // Make sure `self`, `super` etc produce an error when passed to here.
2780 self.extern_prelude.get(&ident.modern()).cloned().and_then(|entry| {
2781 if let Some(binding) = entry.extern_crate_item {
2782 if !speculative && entry.introduced_by_item {
2783 self.record_use(ident, TypeNS, binding, false);
2787 let crate_id = if !speculative {
2788 self.crate_loader.process_path_extern(ident.name, ident.span)
2789 } else if let Some(crate_id) =
2790 self.crate_loader.maybe_process_path_extern(ident.name, ident.span) {
2795 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
2796 Some((crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
2797 .to_name_binding(self.arenas))
2802 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
2803 /// isn't something that can be returned because it can't be made to live that long,
2804 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
2805 /// just that an error occurred.
2806 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
2807 pub fn resolve_str_path_error(
2808 &mut self, span: Span, path_str: &str, ns: Namespace, module_id: NodeId
2809 ) -> Result<(ast::Path, Res), ()> {
2810 let path = if path_str.starts_with("::") {
2813 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
2815 path_str.split("::").skip(1).map(Ident::from_str)
2817 .map(|i| self.new_ast_path_segment(i))
2825 .map(Ident::from_str)
2826 .map(|i| self.new_ast_path_segment(i))
2830 let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| {
2831 let def_id = self.definitions.local_def_id(module_id);
2832 self.module_map.get(&def_id).copied().unwrap_or(self.graph_root)
2834 let parent_scope = &ParentScope::module(module);
2835 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
2839 // Resolve a path passed from rustdoc or HIR lowering.
2840 fn resolve_ast_path(
2844 parent_scope: &ParentScope<'a>,
2845 ) -> Result<Res, (Span, ResolutionError<'a>)> {
2846 match self.resolve_path(
2847 &Segment::from_path(path), Some(ns), parent_scope, true, path.span, CrateLint::No
2849 PathResult::Module(ModuleOrUniformRoot::Module(module)) =>
2850 Ok(module.res().unwrap()),
2851 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
2852 Ok(path_res.base_res()),
2853 PathResult::NonModule(..) => {
2854 Err((path.span, ResolutionError::FailedToResolve {
2855 label: String::from("type-relative paths are not supported in this context"),
2859 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
2860 PathResult::Failed { span, label, suggestion, .. } => {
2861 Err((span, ResolutionError::FailedToResolve {
2869 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
2870 let mut seg = ast::PathSegment::from_ident(ident);
2871 seg.id = self.next_node_id();
2876 pub fn graph_root(&self) -> Module<'a> {
2881 pub fn all_macros(&self) -> &FxHashMap<Name, Res> {
2886 fn names_to_string(names: &[Name]) -> String {
2887 let mut result = String::new();
2888 for (i, name) in names.iter()
2889 .filter(|name| **name != kw::PathRoot)
2892 result.push_str("::");
2894 result.push_str(&name.as_str());
2899 fn path_names_to_string(path: &Path) -> String {
2900 names_to_string(&path.segments.iter()
2901 .map(|seg| seg.ident.name)
2902 .collect::<Vec<_>>())
2905 /// A somewhat inefficient routine to obtain the name of a module.
2906 fn module_to_string(module: Module<'_>) -> Option<String> {
2907 let mut names = Vec::new();
2909 fn collect_mod(names: &mut Vec<Name>, module: Module<'_>) {
2910 if let ModuleKind::Def(.., name) = module.kind {
2911 if let Some(parent) = module.parent {
2913 collect_mod(names, parent);
2916 names.push(Name::intern("<opaque>"));
2917 collect_mod(names, module.parent.unwrap());
2920 collect_mod(&mut names, module);
2922 if names.is_empty() {
2926 Some(names_to_string(&names))
2929 #[derive(Copy, Clone, Debug)]
2931 /// Do not issue the lint.
2934 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
2935 /// In this case, we can take the span of that path.
2938 /// This lint comes from a `use` statement. In this case, what we
2939 /// care about really is the *root* `use` statement; e.g., if we
2940 /// have nested things like `use a::{b, c}`, we care about the
2942 UsePath { root_id: NodeId, root_span: Span },
2944 /// This is the "trait item" from a fully qualified path. For example,
2945 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
2946 /// The `path_span` is the span of the to the trait itself (`X::Y`).
2947 QPathTrait { qpath_id: NodeId, qpath_span: Span },
2951 fn node_id(&self) -> Option<NodeId> {
2953 CrateLint::No => None,
2954 CrateLint::SimplePath(id) |
2955 CrateLint::UsePath { root_id: id, .. } |
2956 CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),