1 // ignore-tidy-filelength
3 //! This crate is responsible for the part of name resolution that doesn't require type checker.
5 //! Module structure of the crate is built here.
6 //! Paths in macros, imports, expressions, types, patterns are resolved here.
7 //! Label and lifetime names are resolved here as well.
9 //! Type-relative name resolution (methods, fields, associated items) happens in `librustc_typeck`.
11 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
12 #![feature(box_patterns)]
13 #![feature(bool_to_option)]
14 #![feature(control_flow_enum)]
15 #![feature(crate_visibility_modifier)]
16 #![feature(format_args_capture)]
18 #![cfg_attr(bootstrap, feature(or_patterns))]
19 #![recursion_limit = "256"]
21 pub use rustc_hir::def::{Namespace, PerNS};
25 use rustc_arena::{DroplessArena, TypedArena};
26 use rustc_ast::node_id::NodeMap;
27 use rustc_ast::ptr::P;
28 use rustc_ast::unwrap_or;
29 use rustc_ast::visit::{self, Visitor};
30 use rustc_ast::{self as ast, NodeId};
31 use rustc_ast::{Crate, CRATE_NODE_ID};
32 use rustc_ast::{Expr, ExprKind, LitKind};
33 use rustc_ast::{ItemKind, ModKind, Path};
34 use rustc_ast_lowering::ResolverAstLowering;
35 use rustc_ast_pretty::pprust;
36 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
37 use rustc_data_structures::ptr_key::PtrKey;
38 use rustc_data_structures::sync::Lrc;
39 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
40 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
41 use rustc_hir::def::Namespace::*;
42 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
43 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
44 use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
45 use rustc_hir::{PrimTy, TraitCandidate};
46 use rustc_index::vec::IndexVec;
47 use rustc_metadata::creader::{CStore, CrateLoader};
48 use rustc_middle::hir::exports::ExportMap;
49 use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn};
50 use rustc_middle::span_bug;
51 use rustc_middle::ty::query::Providers;
52 use rustc_middle::ty::{self, DefIdTree, ResolverOutputs};
53 use rustc_session::lint;
54 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
55 use rustc_session::Session;
56 use rustc_span::edition::Edition;
57 use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency};
58 use rustc_span::source_map::Spanned;
59 use rustc_span::symbol::{kw, sym, Ident, Symbol};
60 use rustc_span::{Span, DUMMY_SP};
62 use smallvec::{smallvec, SmallVec};
63 use std::cell::{Cell, RefCell};
64 use std::collections::BTreeSet;
65 use std::ops::ControlFlow;
66 use std::{cmp, fmt, iter, ptr};
69 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
70 use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion};
71 use imports::{Import, ImportKind, ImportResolver, NameResolution};
72 use late::{ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind::*};
73 use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
75 type Res = def::Res<NodeId>;
77 mod build_reduced_graph;
90 #[derive(Copy, Clone, PartialEq, Debug)]
91 pub enum Determinacy {
97 fn determined(determined: bool) -> Determinacy {
98 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
102 /// A specific scope in which a name can be looked up.
103 /// This enum is currently used only for early resolution (imports and macros),
104 /// but not for late resolution yet.
105 #[derive(Clone, Copy)]
107 DeriveHelpers(ExpnId),
109 MacroRules(MacroRulesScopeRef<'a>),
121 /// Names from different contexts may want to visit different subsets of all specific scopes
122 /// with different restrictions when looking up the resolution.
123 /// This enum is currently used only for early resolution (imports and macros),
124 /// but not for late resolution yet.
126 /// All scopes with the given namespace.
127 All(Namespace, /*is_import*/ bool),
128 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
129 AbsolutePath(Namespace),
130 /// All scopes with macro namespace and the given macro kind restriction.
134 /// Everything you need to know about a name's location to resolve it.
135 /// Serves as a starting point for the scope visitor.
136 /// This struct is currently used only for early resolution (imports and macros),
137 /// but not for late resolution yet.
138 #[derive(Clone, Copy, Debug)]
139 pub struct ParentScope<'a> {
142 macro_rules: MacroRulesScopeRef<'a>,
143 derives: &'a [ast::Path],
146 impl<'a> ParentScope<'a> {
147 /// Creates a parent scope with the passed argument used as the module scope component,
148 /// and other scope components set to default empty values.
149 pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> {
152 expansion: ExpnId::root(),
153 macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty),
159 #[derive(Copy, Debug, Clone)]
160 enum ImplTraitContext {
162 Universal(LocalDefId),
166 struct BindingError {
168 origin: BTreeSet<Span>,
169 target: BTreeSet<Span>,
173 impl PartialOrd for BindingError {
174 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
175 Some(self.cmp(other))
179 impl PartialEq for BindingError {
180 fn eq(&self, other: &BindingError) -> bool {
181 self.name == other.name
185 impl Ord for BindingError {
186 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
187 self.name.cmp(&other.name)
191 enum ResolutionError<'a> {
192 /// Error E0401: can't use type or const parameters from outer function.
193 GenericParamsFromOuterFunction(Res, HasGenericParams),
194 /// Error E0403: the name is already used for a type or const parameter in this generic
196 NameAlreadyUsedInParameterList(Symbol, Span),
197 /// Error E0407: method is not a member of trait.
198 MethodNotMemberOfTrait(Symbol, &'a str),
199 /// Error E0437: type is not a member of trait.
200 TypeNotMemberOfTrait(Symbol, &'a str),
201 /// Error E0438: const is not a member of trait.
202 ConstNotMemberOfTrait(Symbol, &'a str),
203 /// Error E0408: variable `{}` is not bound in all patterns.
204 VariableNotBoundInPattern(&'a BindingError),
205 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
206 VariableBoundWithDifferentMode(Symbol, Span),
207 /// Error E0415: identifier is bound more than once in this parameter list.
208 IdentifierBoundMoreThanOnceInParameterList(Symbol),
209 /// Error E0416: identifier is bound more than once in the same pattern.
210 IdentifierBoundMoreThanOnceInSamePattern(Symbol),
211 /// Error E0426: use of undeclared label.
212 UndeclaredLabel { name: Symbol, suggestion: Option<LabelSuggestion> },
213 /// Error E0429: `self` imports are only allowed within a `{ }` list.
214 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
215 /// Error E0430: `self` import can only appear once in the list.
216 SelfImportCanOnlyAppearOnceInTheList,
217 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
218 SelfImportOnlyInImportListWithNonEmptyPrefix,
219 /// Error E0433: failed to resolve.
220 FailedToResolve { label: String, suggestion: Option<Suggestion> },
221 /// Error E0434: can't capture dynamic environment in a fn item.
222 CannotCaptureDynamicEnvironmentInFnItem,
223 /// Error E0435: attempt to use a non-constant value in a constant.
224 AttemptToUseNonConstantValueInConstant(
226 /* suggestion */ &'static str,
227 /* current */ &'static str,
229 /// Error E0530: `X` bindings cannot shadow `Y`s.
230 BindingShadowsSomethingUnacceptable(&'static str, Symbol, &'a NameBinding<'a>),
231 /// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
232 ForwardDeclaredTyParam, // FIXME(const_generics_defaults)
233 /// ERROR E0770: the type of const parameters must not depend on other generic parameters.
234 ParamInTyOfConstParam(Symbol),
235 /// constant values inside of type parameter defaults must not depend on generic parameters.
236 ParamInAnonConstInTyDefault(Symbol),
237 /// generic parameters must not be used inside const evaluations.
239 /// This error is only emitted when using `min_const_generics`.
240 ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
241 /// Error E0735: generic parameters with a default cannot use `Self`
242 SelfInTyParamDefault,
243 /// Error E0767: use of unreachable label
244 UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
247 enum VisResolutionError<'a> {
248 Relative2018(Span, &'a ast::Path),
250 FailedToResolve(Span, String, Option<Suggestion>),
251 ExpectedFound(Span, String, Res),
256 /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path
257 /// segments' which don't have the rest of an AST or HIR `PathSegment`.
258 #[derive(Clone, Copy, Debug)]
262 /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing
263 /// nonsensical suggestions.
264 has_generic_args: bool,
268 fn from_path(path: &Path) -> Vec<Segment> {
269 path.segments.iter().map(|s| s.into()).collect()
272 fn from_ident(ident: Ident) -> Segment {
273 Segment { ident, id: None, has_generic_args: false }
276 fn names_to_string(segments: &[Segment]) -> String {
277 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
281 impl<'a> From<&'a ast::PathSegment> for Segment {
282 fn from(seg: &'a ast::PathSegment) -> Segment {
283 Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() }
287 struct UsePlacementFinder {
288 target_module: NodeId,
293 impl UsePlacementFinder {
294 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
295 let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
296 if let ControlFlow::Continue(..) = finder.check_mod(&krate.items, CRATE_NODE_ID) {
297 visit::walk_crate(&mut finder, krate);
299 (finder.span, finder.found_use)
302 fn check_mod(&mut self, items: &[P<ast::Item>], node_id: NodeId) -> ControlFlow<()> {
303 if self.span.is_some() {
304 return ControlFlow::Break(());
306 if node_id != self.target_module {
307 return ControlFlow::Continue(());
309 // find a use statement
312 ItemKind::Use(..) => {
313 // don't suggest placing a use before the prelude
314 // import or other generated ones
315 if !item.span.from_expansion() {
316 self.span = Some(item.span.shrink_to_lo());
317 self.found_use = true;
318 return ControlFlow::Break(());
321 // don't place use before extern crate
322 ItemKind::ExternCrate(_) => {}
323 // but place them before the first other item
325 if self.span.map_or(true, |span| item.span < span)
326 && !item.span.from_expansion()
328 // don't insert between attributes and an item
329 if item.attrs.is_empty() {
330 self.span = Some(item.span.shrink_to_lo());
332 // find the first attribute on the item
333 for attr in &item.attrs {
334 if self.span.map_or(true, |span| attr.span < span) {
335 self.span = Some(attr.span.shrink_to_lo());
343 ControlFlow::Continue(())
347 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
348 fn visit_item(&mut self, item: &'tcx ast::Item) {
349 if let ItemKind::Mod(_, ModKind::Loaded(items, ..)) = &item.kind {
350 if let ControlFlow::Break(..) = self.check_mod(items, item.id) {
354 visit::walk_item(self, item);
358 /// An intermediate resolution result.
360 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
361 /// items are visible in their whole block, while `Res`es only from the place they are defined
364 enum LexicalScopeBinding<'a> {
365 Item(&'a NameBinding<'a>),
369 impl<'a> LexicalScopeBinding<'a> {
370 fn res(self) -> Res {
372 LexicalScopeBinding::Item(binding) => binding.res(),
373 LexicalScopeBinding::Res(res) => res,
378 #[derive(Copy, Clone, Debug)]
379 enum ModuleOrUniformRoot<'a> {
383 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
384 CrateRootAndExternPrelude,
386 /// Virtual module that denotes resolution in extern prelude.
387 /// Used for paths starting with `::` on 2018 edition.
390 /// Virtual module that denotes resolution in current scope.
391 /// Used only for resolving single-segment imports. The reason it exists is that import paths
392 /// are always split into two parts, the first of which should be some kind of module.
396 impl ModuleOrUniformRoot<'_> {
397 fn same_def(lhs: Self, rhs: Self) -> bool {
399 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
400 lhs.def_id() == rhs.def_id()
403 ModuleOrUniformRoot::CrateRootAndExternPrelude,
404 ModuleOrUniformRoot::CrateRootAndExternPrelude,
406 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
407 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
413 #[derive(Clone, Debug)]
414 enum PathResult<'a> {
415 Module(ModuleOrUniformRoot<'a>),
416 NonModule(PartialRes),
421 suggestion: Option<Suggestion>,
422 is_error_from_last_segment: bool,
428 /// An anonymous module; e.g., just a block.
433 /// { // This is an anonymous module
434 /// f(); // This resolves to (2) as we are inside the block.
437 /// f(); // Resolves to (1)
441 /// Any module with a name.
445 /// * A normal module – either `mod from_file;` or `mod from_block { }` –
446 /// or the crate root (which is conceptually a top-level module).
447 /// Note that the crate root's [name][Self::name] will be [`kw::Empty`].
448 /// * A trait or an enum (it implicitly contains associated types, methods and variant
450 Def(DefKind, DefId, Symbol),
454 /// Get name of the module.
455 pub fn name(&self) -> Option<Symbol> {
457 ModuleKind::Block(..) => None,
458 ModuleKind::Def(.., name) => Some(*name),
463 /// A key that identifies a binding in a given `Module`.
465 /// Multiple bindings in the same module can have the same key (in a valid
466 /// program) if all but one of them come from glob imports.
467 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
469 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
473 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
474 /// `_` in the expanded AST that introduced this binding.
478 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
480 /// One node in the tree of modules.
482 /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these:
485 /// * crate root (aka, top-level anonymous module)
488 /// * curly-braced block with statements
490 /// You can use [`ModuleData::kind`] to determine the kind of module this is.
491 pub struct ModuleData<'a> {
492 /// The direct parent module (it may not be a `mod`, however).
493 parent: Option<Module<'a>>,
494 /// What kind of module this is, because this may not be a `mod`.
497 /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module).
498 /// This may be the crate root.
499 nearest_parent_mod: DefId,
501 /// Mapping between names and their (possibly in-progress) resolutions in this module.
502 /// Resolutions in modules from other crates are not populated until accessed.
503 lazy_resolutions: Resolutions<'a>,
504 /// True if this is a module from other crate that needs to be populated on access.
505 populate_on_access: Cell<bool>,
507 /// Macro invocations that can expand into items in this module.
508 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
510 /// Whether `#[no_implicit_prelude]` is active.
511 no_implicit_prelude: bool,
513 glob_importers: RefCell<Vec<&'a Import<'a>>>,
514 globs: RefCell<Vec<&'a Import<'a>>>,
516 /// Used to memoize the traits in this module for faster searches through all traits in scope.
517 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
519 /// Span of the module itself. Used for error reporting.
525 type Module<'a> = &'a ModuleData<'a>;
527 impl<'a> ModuleData<'a> {
529 parent: Option<Module<'a>>,
531 nearest_parent_mod: DefId,
539 lazy_resolutions: Default::default(),
540 populate_on_access: Cell::new(!nearest_parent_mod.is_local()),
541 unexpanded_invocations: Default::default(),
542 no_implicit_prelude: false,
543 glob_importers: RefCell::new(Vec::new()),
544 globs: RefCell::new(Vec::new()),
545 traits: RefCell::new(None),
551 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
553 R: AsMut<Resolver<'a>>,
554 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
556 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
557 if let Some(binding) = name_resolution.borrow().binding {
558 f(resolver, key.ident, key.ns, binding);
563 /// This modifies `self` in place. The traits will be stored in `self.traits`.
564 fn ensure_traits<R>(&'a self, resolver: &mut R)
566 R: AsMut<Resolver<'a>>,
568 let mut traits = self.traits.borrow_mut();
569 if traits.is_none() {
570 let mut collected_traits = Vec::new();
571 self.for_each_child(resolver, |_, name, ns, binding| {
575 if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() {
576 collected_traits.push((name, binding))
579 *traits = Some(collected_traits.into_boxed_slice());
583 fn res(&self) -> Option<Res> {
585 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
590 fn def_id(&self) -> Option<DefId> {
592 ModuleKind::Def(_, def_id, _) => Some(def_id),
597 // `self` resolves to the first module ancestor that `is_normal`.
598 fn is_normal(&self) -> bool {
599 matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
602 fn is_trait(&self) -> bool {
603 matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
606 fn nearest_item_scope(&'a self) -> Module<'a> {
608 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
609 self.parent.expect("enum or trait module without a parent")
615 fn is_ancestor_of(&self, mut other: &Self) -> bool {
616 while !ptr::eq(self, other) {
617 if let Some(parent) = other.parent {
627 impl<'a> fmt::Debug for ModuleData<'a> {
628 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
629 write!(f, "{:?}", self.res())
633 /// Records a possibly-private value, type, or module definition.
634 #[derive(Clone, Debug)]
635 pub struct NameBinding<'a> {
636 kind: NameBindingKind<'a>,
637 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
643 pub trait ToNameBinding<'a> {
644 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
647 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
648 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
653 #[derive(Clone, Debug)]
654 enum NameBindingKind<'a> {
655 Res(Res, /* is_macro_export */ bool),
657 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
660 impl<'a> NameBindingKind<'a> {
661 /// Is this a name binding of a import?
662 fn is_import(&self) -> bool {
663 matches!(*self, NameBindingKind::Import { .. })
667 struct PrivacyError<'a> {
669 binding: &'a NameBinding<'a>,
673 struct UseError<'a> {
674 err: DiagnosticBuilder<'a>,
675 /// Candidates which user could `use` to access the missing type.
676 candidates: Vec<ImportSuggestion>,
677 /// The `DefId` of the module to place the use-statements in.
679 /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`).
681 /// Extra free-form suggestion.
682 suggestion: Option<(Span, &'static str, String, Applicability)>,
685 #[derive(Clone, Copy, PartialEq, Debug)]
690 MacroRulesVsModularized,
698 fn descr(self) -> &'static str {
700 AmbiguityKind::Import => "name vs any other name during import resolution",
701 AmbiguityKind::BuiltinAttr => "built-in attribute vs any other name",
702 AmbiguityKind::DeriveHelper => "derive helper attribute vs any other name",
703 AmbiguityKind::MacroRulesVsModularized => {
704 "`macro_rules` vs non-`macro_rules` from other module"
706 AmbiguityKind::GlobVsOuter => {
707 "glob import vs any other name from outer scope during import/macro resolution"
709 AmbiguityKind::GlobVsGlob => "glob import vs glob import in the same module",
710 AmbiguityKind::GlobVsExpanded => {
711 "glob import vs macro-expanded name in the same \
712 module during import/macro resolution"
714 AmbiguityKind::MoreExpandedVsOuter => {
715 "macro-expanded name vs less macro-expanded name \
716 from outer scope during import/macro resolution"
722 /// Miscellaneous bits of metadata for better ambiguity error reporting.
723 #[derive(Clone, Copy, PartialEq)]
724 enum AmbiguityErrorMisc {
731 struct AmbiguityError<'a> {
734 b1: &'a NameBinding<'a>,
735 b2: &'a NameBinding<'a>,
736 misc1: AmbiguityErrorMisc,
737 misc2: AmbiguityErrorMisc,
740 impl<'a> NameBinding<'a> {
741 fn module(&self) -> Option<Module<'a>> {
743 NameBindingKind::Module(module) => Some(module),
744 NameBindingKind::Import { binding, .. } => binding.module(),
749 fn res(&self) -> Res {
751 NameBindingKind::Res(res, _) => res,
752 NameBindingKind::Module(module) => module.res().unwrap(),
753 NameBindingKind::Import { binding, .. } => binding.res(),
757 fn is_ambiguity(&self) -> bool {
758 self.ambiguity.is_some()
760 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
765 fn is_possibly_imported_variant(&self) -> bool {
767 NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
768 NameBindingKind::Res(
769 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
772 NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
776 fn is_extern_crate(&self) -> bool {
778 NameBindingKind::Import {
779 import: &Import { kind: ImportKind::ExternCrate { .. }, .. },
782 NameBindingKind::Module(&ModuleData {
783 kind: ModuleKind::Def(DefKind::Mod, def_id, _),
785 }) => def_id.index == CRATE_DEF_INDEX,
790 fn is_import(&self) -> bool {
791 matches!(self.kind, NameBindingKind::Import { .. })
794 fn is_glob_import(&self) -> bool {
796 NameBindingKind::Import { import, .. } => import.is_glob(),
801 fn is_importable(&self) -> bool {
804 Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
808 fn is_macro_def(&self) -> bool {
809 matches!(self.kind, NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _))
812 fn macro_kind(&self) -> Option<MacroKind> {
813 self.res().macro_kind()
816 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
817 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
818 // Then this function returns `true` if `self` may emerge from a macro *after* that
819 // in some later round and screw up our previously found resolution.
820 // See more detailed explanation in
821 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
822 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
823 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
824 // Expansions are partially ordered, so "may appear after" is an inversion of
825 // "certainly appears before or simultaneously" and includes unordered cases.
826 let self_parent_expansion = self.expansion;
827 let other_parent_expansion = binding.expansion;
828 let certainly_before_other_or_simultaneously =
829 other_parent_expansion.is_descendant_of(self_parent_expansion);
830 let certainly_before_invoc_or_simultaneously =
831 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
832 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
836 #[derive(Debug, Default, Clone)]
837 pub struct ExternPreludeEntry<'a> {
838 extern_crate_item: Option<&'a NameBinding<'a>>,
839 pub introduced_by_item: bool,
842 /// Used for better errors for E0773
843 enum BuiltinMacroState {
844 NotYetSeen(SyntaxExtensionKind),
848 /// The main resolver class.
850 /// This is the visitor that walks the whole crate.
851 pub struct Resolver<'a> {
852 session: &'a Session,
854 definitions: Definitions,
856 graph_root: Module<'a>,
858 prelude: Option<Module<'a>>,
859 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
861 /// N.B., this is used only for better diagnostics, not name resolution itself.
862 has_self: FxHashSet<DefId>,
864 /// Names of fields of an item `DefId` accessible with dot syntax.
865 /// Used for hints during error reporting.
866 field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>,
868 /// All imports known to succeed or fail.
869 determined_imports: Vec<&'a Import<'a>>,
871 /// All non-determined imports.
872 indeterminate_imports: Vec<&'a Import<'a>>,
874 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
875 /// We are resolving a last import segment during import validation.
876 last_import_segment: bool,
877 /// This binding should be ignored during in-module resolution, so that we don't get
878 /// "self-confirming" import resolutions during import validation.
879 unusable_binding: Option<&'a NameBinding<'a>>,
881 /// Resolutions for nodes that have a single resolution.
882 partial_res_map: NodeMap<PartialRes>,
883 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
884 import_res_map: NodeMap<PerNS<Option<Res>>>,
885 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
886 label_res_map: NodeMap<NodeId>,
888 /// `CrateNum` resolutions of `extern crate` items.
889 extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
890 export_map: ExportMap<LocalDefId>,
891 trait_map: NodeMap<Vec<TraitCandidate>>,
893 /// A map from nodes to anonymous modules.
894 /// Anonymous modules are pseudo-modules that are implicitly created around items
895 /// contained within blocks.
897 /// For example, if we have this:
905 /// There will be an anonymous module created around `g` with the ID of the
906 /// entry block for `f`.
907 block_map: NodeMap<Module<'a>>,
908 /// A fake module that contains no definition and no prelude. Used so that
909 /// some AST passes can generate identifiers that only resolve to local or
911 empty_module: Module<'a>,
912 module_map: FxHashMap<LocalDefId, Module<'a>>,
913 extern_module_map: FxHashMap<DefId, Module<'a>>,
914 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
915 underscore_disambiguator: u32,
917 /// Maps glob imports to the names of items actually imported.
918 glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
919 /// Visibilities in "lowered" form, for all entities that have them.
920 visibilities: FxHashMap<LocalDefId, ty::Visibility>,
921 used_imports: FxHashSet<(NodeId, Namespace)>,
922 maybe_unused_trait_imports: FxHashSet<LocalDefId>,
923 maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
925 /// Privacy errors are delayed until the end in order to deduplicate them.
926 privacy_errors: Vec<PrivacyError<'a>>,
927 /// Ambiguity errors are delayed for deduplication.
928 ambiguity_errors: Vec<AmbiguityError<'a>>,
929 /// `use` injections are delayed for better placement and deduplication.
930 use_injections: Vec<UseError<'a>>,
931 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
932 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
934 arenas: &'a ResolverArenas<'a>,
935 dummy_binding: &'a NameBinding<'a>,
937 crate_loader: CrateLoader<'a>,
938 macro_names: FxHashSet<Ident>,
939 builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
940 registered_attrs: FxHashSet<Ident>,
941 registered_tools: FxHashSet<Ident>,
942 macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
943 all_macros: FxHashMap<Symbol, Res>,
944 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
945 dummy_ext_bang: Lrc<SyntaxExtension>,
946 dummy_ext_derive: Lrc<SyntaxExtension>,
947 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
948 local_macro_def_scopes: FxHashMap<LocalDefId, Module<'a>>,
949 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
950 unused_macros: FxHashMap<LocalDefId, (NodeId, Span)>,
951 proc_macro_stubs: FxHashSet<LocalDefId>,
952 /// Traces collected during macro resolution and validated when it's complete.
953 single_segment_macro_resolutions:
954 Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>,
955 multi_segment_macro_resolutions:
956 Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>,
957 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
958 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
959 /// Derive macros cannot modify the item themselves and have to store the markers in the global
960 /// context, so they attach the markers to derive container IDs using this resolver table.
961 containers_deriving_copy: FxHashSet<ExpnId>,
962 /// Parent scopes in which the macros were invoked.
963 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
964 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
965 /// `macro_rules` scopes *produced* by expanding the macro invocations,
966 /// include all the `macro_rules` items and other invocations generated by them.
967 output_macro_rules_scopes: FxHashMap<ExpnId, MacroRulesScopeRef<'a>>,
968 /// Helper attributes that are in scope for the given expansion.
969 helper_attrs: FxHashMap<ExpnId, Vec<Ident>>,
970 /// Resolutions for paths inside the `#[derive(...)]` attribute with the given `ExpnId`.
971 derive_resolutions: FxHashMap<ExpnId, Vec<(Lrc<SyntaxExtension>, ast::Path)>>,
973 /// Avoid duplicated errors for "name already defined".
974 name_already_seen: FxHashMap<Symbol, Span>,
976 potentially_unused_imports: Vec<&'a Import<'a>>,
978 /// Table for mapping struct IDs into struct constructor IDs,
979 /// it's not used during normal resolution, only for better error reporting.
980 /// Also includes of list of each fields visibility
981 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
983 /// Features enabled for this crate.
984 active_features: FxHashSet<Symbol>,
986 lint_buffer: LintBuffer,
988 next_node_id: NodeId,
990 def_id_to_span: IndexVec<LocalDefId, Span>,
992 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
993 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
995 /// Indices of unnamed struct or variant fields with unresolved attributes.
996 placeholder_field_indices: FxHashMap<NodeId, usize>,
997 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
998 /// we know what parent node that fragment should be attached to thanks to this table,
999 /// and how the `impl Trait` fragments were introduced.
1000 invocation_parents: FxHashMap<ExpnId, (LocalDefId, ImplTraitContext)>,
1002 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1003 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1004 /// FIXME: Replace with a more general AST map (together with some other fields).
1005 trait_impl_items: FxHashSet<LocalDefId>,
1007 legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
1010 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1012 pub struct ResolverArenas<'a> {
1013 modules: TypedArena<ModuleData<'a>>,
1014 local_modules: RefCell<Vec<Module<'a>>>,
1015 imports: TypedArena<Import<'a>>,
1016 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1017 ast_paths: TypedArena<ast::Path>,
1018 dropless: DroplessArena,
1021 impl<'a> ResolverArenas<'a> {
1022 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1023 let module = self.modules.alloc(module);
1024 if module.def_id().map_or(true, |def_id| def_id.is_local()) {
1025 self.local_modules.borrow_mut().push(module);
1029 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1030 self.local_modules.borrow()
1032 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1033 self.dropless.alloc(name_binding)
1035 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1036 self.imports.alloc(import)
1038 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1039 self.name_resolutions.alloc(Default::default())
1041 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1042 PtrKey(self.dropless.alloc(Cell::new(scope)))
1044 fn alloc_macro_rules_binding(
1046 binding: MacroRulesBinding<'a>,
1047 ) -> &'a MacroRulesBinding<'a> {
1048 self.dropless.alloc(binding)
1050 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1051 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1053 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1054 self.dropless.alloc_from_iter(spans)
1058 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1059 fn as_mut(&mut self) -> &mut Resolver<'a> {
1064 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1065 fn parent(self, id: DefId) -> Option<DefId> {
1066 match id.as_local() {
1067 Some(id) => self.definitions.def_key(id).parent,
1068 None => self.cstore().def_key(id).parent,
1070 .map(|index| DefId { index, ..id })
1074 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1075 /// the resolver is no longer needed as all the relevant information is inline.
1076 impl ResolverAstLowering for Resolver<'_> {
1077 fn def_key(&mut self, id: DefId) -> DefKey {
1078 if let Some(id) = id.as_local() {
1079 self.definitions().def_key(id)
1081 self.cstore().def_key(id)
1085 fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
1086 self.cstore().item_generics_num_lifetimes(def_id, sess)
1089 fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
1090 self.legacy_const_generic_args(expr)
1093 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1094 self.partial_res_map.get(&id).cloned()
1097 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1098 self.import_res_map.get(&id).cloned().unwrap_or_default()
1101 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1102 self.label_res_map.get(&id).cloned()
1105 fn definitions(&mut self) -> &mut Definitions {
1106 &mut self.definitions
1109 fn lint_buffer(&mut self) -> &mut LintBuffer {
1110 &mut self.lint_buffer
1113 fn next_node_id(&mut self) -> NodeId {
1117 fn trait_map(&self) -> &NodeMap<Vec<TraitCandidate>> {
1121 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1122 self.node_id_to_def_id.get(&node).copied()
1125 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1126 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1129 /// Adds a definition with a parent definition.
1133 node_id: ast::NodeId,
1139 !self.node_id_to_def_id.contains_key(&node_id),
1140 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1143 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1146 // Find the next free disambiguator for this key.
1147 let next_disambiguator = &mut self.next_disambiguator;
1148 let next_disambiguator = |parent, data| {
1149 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1150 let disambiguator = *next_disamb;
1151 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1155 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator);
1157 assert_eq!(self.def_id_to_span.push(span), def_id);
1159 // Some things for which we allocate `LocalDefId`s don't correspond to
1160 // anything in the AST, so they don't have a `NodeId`. For these cases
1161 // we don't need a mapping from `NodeId` to `LocalDefId`.
1162 if node_id != ast::DUMMY_NODE_ID {
1163 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1164 self.node_id_to_def_id.insert(node_id, def_id);
1166 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1172 impl<'a> Resolver<'a> {
1174 session: &'a Session,
1177 metadata_loader: &'a MetadataLoaderDyn,
1178 arenas: &'a ResolverArenas<'a>,
1180 let root_local_def_id = LocalDefId { local_def_index: CRATE_DEF_INDEX };
1181 let root_def_id = root_local_def_id.to_def_id();
1182 let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1183 let graph_root = arenas.alloc_module(ModuleData {
1184 no_implicit_prelude: session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1185 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1187 let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1188 let empty_module = arenas.alloc_module(ModuleData {
1189 no_implicit_prelude: true,
1198 let mut module_map = FxHashMap::default();
1199 module_map.insert(root_local_def_id, graph_root);
1201 let definitions = Definitions::new(crate_name, session.local_crate_disambiguator());
1202 let root = definitions.get_root_def();
1204 let mut visibilities = FxHashMap::default();
1205 visibilities.insert(root_local_def_id, ty::Visibility::Public);
1207 let mut def_id_to_span = IndexVec::default();
1208 assert_eq!(def_id_to_span.push(rustc_span::DUMMY_SP), root);
1209 let mut def_id_to_node_id = IndexVec::default();
1210 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1211 let mut node_id_to_def_id = FxHashMap::default();
1212 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1214 let mut invocation_parents = FxHashMap::default();
1215 invocation_parents.insert(ExpnId::root(), (root, ImplTraitContext::Existential));
1217 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1221 .filter(|(_, entry)| entry.add_prelude)
1222 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1225 if !session.contains_name(&krate.attrs, sym::no_core) {
1226 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1227 if !session.contains_name(&krate.attrs, sym::no_std) {
1228 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1232 let (registered_attrs, registered_tools) =
1233 macros::registered_attrs_and_tools(session, &krate.attrs);
1235 let features = session.features_untracked();
1236 let non_macro_attr =
1237 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1239 let mut resolver = Resolver {
1244 // The outermost module has def ID 0; this is not reflected in the
1250 has_self: FxHashSet::default(),
1251 field_names: FxHashMap::default(),
1253 determined_imports: Vec::new(),
1254 indeterminate_imports: Vec::new(),
1256 last_import_segment: false,
1257 unusable_binding: None,
1259 partial_res_map: Default::default(),
1260 import_res_map: Default::default(),
1261 label_res_map: Default::default(),
1262 extern_crate_map: Default::default(),
1263 export_map: FxHashMap::default(),
1264 trait_map: Default::default(),
1265 underscore_disambiguator: 0,
1268 block_map: Default::default(),
1269 extern_module_map: FxHashMap::default(),
1270 binding_parent_modules: FxHashMap::default(),
1271 ast_transform_scopes: FxHashMap::default(),
1273 glob_map: Default::default(),
1275 used_imports: FxHashSet::default(),
1276 maybe_unused_trait_imports: Default::default(),
1277 maybe_unused_extern_crates: Vec::new(),
1279 privacy_errors: Vec::new(),
1280 ambiguity_errors: Vec::new(),
1281 use_injections: Vec::new(),
1282 macro_expanded_macro_export_errors: BTreeSet::new(),
1285 dummy_binding: arenas.alloc_name_binding(NameBinding {
1286 kind: NameBindingKind::Res(Res::Err, false),
1288 expansion: ExpnId::root(),
1290 vis: ty::Visibility::Public,
1293 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1294 macro_names: FxHashSet::default(),
1295 builtin_macros: Default::default(),
1298 macro_use_prelude: FxHashMap::default(),
1299 all_macros: FxHashMap::default(),
1300 macro_map: FxHashMap::default(),
1301 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1302 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1303 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1304 invocation_parent_scopes: Default::default(),
1305 output_macro_rules_scopes: Default::default(),
1306 helper_attrs: Default::default(),
1307 derive_resolutions: Default::default(),
1308 local_macro_def_scopes: FxHashMap::default(),
1309 name_already_seen: FxHashMap::default(),
1310 potentially_unused_imports: Vec::new(),
1311 struct_constructors: Default::default(),
1312 unused_macros: Default::default(),
1313 proc_macro_stubs: Default::default(),
1314 single_segment_macro_resolutions: Default::default(),
1315 multi_segment_macro_resolutions: Default::default(),
1316 builtin_attrs: Default::default(),
1317 containers_deriving_copy: Default::default(),
1318 active_features: features
1319 .declared_lib_features
1321 .map(|(feat, ..)| *feat)
1322 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1324 lint_buffer: LintBuffer::default(),
1325 next_node_id: NodeId::from_u32(1),
1329 placeholder_field_indices: Default::default(),
1331 next_disambiguator: Default::default(),
1332 trait_impl_items: Default::default(),
1333 legacy_const_generic_args: Default::default(),
1336 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1337 resolver.invocation_parent_scopes.insert(ExpnId::root(), root_parent_scope);
1342 pub fn next_node_id(&mut self) -> NodeId {
1347 .expect("input too large; ran out of NodeIds");
1348 self.next_node_id = ast::NodeId::from_usize(next);
1352 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1353 &mut self.lint_buffer
1356 pub fn arenas() -> ResolverArenas<'a> {
1360 pub fn into_outputs(self) -> ResolverOutputs {
1361 let definitions = self.definitions;
1362 let visibilities = self.visibilities;
1363 let extern_crate_map = self.extern_crate_map;
1364 let export_map = self.export_map;
1365 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1366 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1367 let glob_map = self.glob_map;
1370 cstore: Box::new(self.crate_loader.into_cstore()),
1375 maybe_unused_trait_imports,
1376 maybe_unused_extern_crates,
1377 extern_prelude: self
1380 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1385 pub fn clone_outputs(&self) -> ResolverOutputs {
1387 definitions: self.definitions.clone(),
1388 cstore: Box::new(self.cstore().clone()),
1389 visibilities: self.visibilities.clone(),
1390 extern_crate_map: self.extern_crate_map.clone(),
1391 export_map: self.export_map.clone(),
1392 glob_map: self.glob_map.clone(),
1393 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1394 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1395 extern_prelude: self
1398 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1403 pub fn cstore(&self) -> &CStore {
1404 self.crate_loader.cstore()
1407 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1408 self.non_macro_attrs[mark_used as usize].clone()
1411 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1413 MacroKind::Bang => self.dummy_ext_bang.clone(),
1414 MacroKind::Derive => self.dummy_ext_derive.clone(),
1415 MacroKind::Attr => self.non_macro_attr(true),
1419 /// Runs the function on each namespace.
1420 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1426 fn is_builtin_macro(&mut self, res: Res) -> bool {
1427 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1430 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1432 match ctxt.outer_expn_data().macro_def_id {
1433 Some(def_id) => return def_id,
1434 None => ctxt.remove_mark(),
1439 /// Entry point to crate resolution.
1440 pub fn resolve_crate(&mut self, krate: &Crate) {
1441 self.session.time("resolve_crate", || {
1442 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1443 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1444 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1445 self.session.time("resolve_check_unused", || self.check_unused(krate));
1446 self.session.time("resolve_report_errors", || self.report_errors(krate));
1447 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1451 pub fn traits_in_scope(
1453 current_trait: Option<Module<'a>>,
1454 parent_scope: &ParentScope<'a>,
1455 ctxt: SyntaxContext,
1456 assoc_item: Option<(Symbol, Namespace)>,
1457 ) -> Vec<TraitCandidate> {
1458 let mut found_traits = Vec::new();
1460 if let Some(module) = current_trait {
1461 if self.trait_may_have_item(Some(module), assoc_item) {
1462 let def_id = module.def_id().unwrap();
1463 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1467 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1469 Scope::Module(module) => {
1470 this.traits_in_module(module, assoc_item, &mut found_traits);
1472 Scope::StdLibPrelude => {
1473 if let Some(module) = this.prelude {
1474 this.traits_in_module(module, assoc_item, &mut found_traits);
1477 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1478 _ => unreachable!(),
1486 fn traits_in_module(
1489 assoc_item: Option<(Symbol, Namespace)>,
1490 found_traits: &mut Vec<TraitCandidate>,
1492 module.ensure_traits(self);
1493 let traits = module.traits.borrow();
1494 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1495 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1496 let def_id = trait_binding.res().def_id();
1497 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1498 found_traits.push(TraitCandidate { def_id, import_ids });
1503 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1504 // associated item with the given name and namespace (if specified). This is a conservative
1505 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1506 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1507 // associated items.
1508 fn trait_may_have_item(
1510 trait_module: Option<Module<'a>>,
1511 assoc_item: Option<(Symbol, Namespace)>,
1513 match (trait_module, assoc_item) {
1514 (Some(trait_module), Some((name, ns))) => {
1515 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1516 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1517 assoc_ns == ns && assoc_ident.name == name
1524 fn find_transitive_imports(
1526 mut kind: &NameBindingKind<'_>,
1528 ) -> SmallVec<[LocalDefId; 1]> {
1529 let mut import_ids = smallvec![];
1530 while let NameBindingKind::Import { import, binding, .. } = kind {
1531 let id = self.local_def_id(import.id);
1532 self.maybe_unused_trait_imports.insert(id);
1533 self.add_to_glob_map(&import, trait_name);
1534 import_ids.push(id);
1535 kind = &binding.kind;
1544 nearest_parent_mod: DefId,
1548 let module = ModuleData::new(Some(parent), kind, nearest_parent_mod, expn_id, span);
1549 self.arenas.alloc_module(module)
1552 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1553 let ident = ident.normalize_to_macros_2_0();
1554 let disambiguator = if ident.name == kw::Underscore {
1555 self.underscore_disambiguator += 1;
1556 self.underscore_disambiguator
1560 BindingKey { ident, ns, disambiguator }
1563 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1564 if module.populate_on_access.get() {
1565 module.populate_on_access.set(false);
1566 self.build_reduced_graph_external(module);
1568 &module.lazy_resolutions
1575 ) -> &'a RefCell<NameResolution<'a>> {
1577 .resolutions(module)
1580 .or_insert_with(|| self.arenas.alloc_name_resolution())
1587 used_binding: &'a NameBinding<'a>,
1588 is_lexical_scope: bool,
1590 if let Some((b2, kind)) = used_binding.ambiguity {
1591 self.ambiguity_errors.push(AmbiguityError {
1596 misc1: AmbiguityErrorMisc::None,
1597 misc2: AmbiguityErrorMisc::None,
1600 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1601 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1602 // but not introduce it, as used if they are accessed from lexical scope.
1603 if is_lexical_scope {
1604 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1605 if let Some(crate_item) = entry.extern_crate_item {
1606 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1613 import.used.set(true);
1614 self.used_imports.insert((import.id, ns));
1615 self.add_to_glob_map(&import, ident);
1616 self.record_use(ident, ns, binding, false);
1621 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1622 if import.is_glob() {
1623 let def_id = self.local_def_id(import.id);
1624 self.glob_map.entry(def_id).or_default().insert(ident.name);
1628 /// A generic scope visitor.
1629 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1630 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1633 scope_set: ScopeSet,
1634 parent_scope: &ParentScope<'a>,
1635 ctxt: SyntaxContext,
1636 mut visitor: impl FnMut(
1639 /*use_prelude*/ bool,
1643 // General principles:
1644 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1645 // built into the language or standard library. This way we can add new names into the
1646 // language or standard library without breaking user code.
1647 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1648 // Places to search (in order of decreasing priority):
1650 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1651 // (open set, not controlled).
1652 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1653 // (open, not controlled).
1654 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1655 // 4. Tool modules (closed, controlled right now, but not in the future).
1656 // 5. Standard library prelude (de-facto closed, controlled).
1657 // 6. Language prelude (closed, controlled).
1659 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1660 // (open set, not controlled).
1661 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1662 // (open, not controlled).
1663 // 3. Standard library prelude (de-facto closed, controlled).
1665 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1666 // are currently reported as errors. They should be higher in priority than preludes
1667 // and probably even names in modules according to the "general principles" above. They
1668 // also should be subject to restricted shadowing because are effectively produced by
1669 // derives (you need to resolve the derive first to add helpers into scope), but they
1670 // should be available before the derive is expanded for compatibility.
1671 // It's mess in general, so we are being conservative for now.
1672 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1673 // priority than prelude macros, but create ambiguities with macros in modules.
1674 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1675 // (open, not controlled). Have higher priority than prelude macros, but create
1676 // ambiguities with `macro_rules`.
1677 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1678 // 4a. User-defined prelude from macro-use
1679 // (open, the open part is from macro expansions, not controlled).
1680 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1681 // 4c. Standard library prelude (de-facto closed, controlled).
1682 // 6. Language prelude: builtin attributes (closed, controlled).
1684 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1685 let (ns, macro_kind, is_absolute_path) = match scope_set {
1686 ScopeSet::All(ns, _) => (ns, None, false),
1687 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1688 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1690 // Jump out of trait or enum modules, they do not act as scopes.
1691 let module = parent_scope.module.nearest_item_scope();
1692 let mut scope = match ns {
1693 _ if is_absolute_path => Scope::CrateRoot,
1694 TypeNS | ValueNS => Scope::Module(module),
1695 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1697 let mut ctxt = ctxt.normalize_to_macros_2_0();
1698 let mut use_prelude = !module.no_implicit_prelude;
1701 let visit = match scope {
1702 // Derive helpers are not in scope when resolving derives in the same container.
1703 Scope::DeriveHelpers(expn_id) => {
1704 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1706 Scope::DeriveHelpersCompat => true,
1707 Scope::MacroRules(macro_rules_scope) => {
1708 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1709 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1710 // As another consequence of this optimization visitors never observe invocation
1711 // scopes for macros that were already expanded.
1712 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1713 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1714 macro_rules_scope.set(next_scope.get());
1721 Scope::CrateRoot => true,
1722 Scope::Module(..) => true,
1723 Scope::RegisteredAttrs => use_prelude,
1724 Scope::MacroUsePrelude => use_prelude || rust_2015,
1725 Scope::BuiltinAttrs => true,
1726 Scope::ExternPrelude => use_prelude || is_absolute_path,
1727 Scope::ToolPrelude => use_prelude,
1728 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1729 Scope::BuiltinTypes => true,
1733 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1734 return break_result;
1738 scope = match scope {
1739 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1740 // Derive helpers are not visible to code generated by bang or derive macros.
1741 let expn_data = expn_id.expn_data();
1742 match expn_data.kind {
1744 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1745 Scope::DeriveHelpersCompat
1747 _ => Scope::DeriveHelpers(expn_data.parent),
1750 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1751 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1752 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1753 MacroRulesScope::Binding(binding) => {
1754 Scope::MacroRules(binding.parent_macro_rules_scope)
1756 MacroRulesScope::Invocation(invoc_id) => {
1757 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1759 MacroRulesScope::Empty => Scope::Module(module),
1761 Scope::CrateRoot => match ns {
1763 ctxt.adjust(ExpnId::root());
1764 Scope::ExternPrelude
1766 ValueNS | MacroNS => break,
1768 Scope::Module(module) => {
1769 use_prelude = !module.no_implicit_prelude;
1770 match self.hygienic_lexical_parent(module, &mut ctxt) {
1771 Some(parent_module) => Scope::Module(parent_module),
1773 ctxt.adjust(ExpnId::root());
1775 TypeNS => Scope::ExternPrelude,
1776 ValueNS => Scope::StdLibPrelude,
1777 MacroNS => Scope::RegisteredAttrs,
1782 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1783 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1784 Scope::BuiltinAttrs => break, // nowhere else to search
1785 Scope::ExternPrelude if is_absolute_path => break,
1786 Scope::ExternPrelude => Scope::ToolPrelude,
1787 Scope::ToolPrelude => Scope::StdLibPrelude,
1788 Scope::StdLibPrelude => match ns {
1789 TypeNS => Scope::BuiltinTypes,
1790 ValueNS => break, // nowhere else to search
1791 MacroNS => Scope::BuiltinAttrs,
1793 Scope::BuiltinTypes => break, // nowhere else to search
1800 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1801 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1802 /// `ident` in the first scope that defines it (or None if no scopes define it).
1804 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1805 /// the items are defined in the block. For example,
1808 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1811 /// g(); // This resolves to the local variable `g` since it shadows the item.
1815 /// Invariant: This must only be called during main resolution, not during
1816 /// import resolution.
1817 fn resolve_ident_in_lexical_scope(
1821 parent_scope: &ParentScope<'a>,
1822 record_used_id: Option<NodeId>,
1825 ) -> Option<LexicalScopeBinding<'a>> {
1826 assert!(ns == TypeNS || ns == ValueNS);
1827 if ident.name == kw::Empty {
1828 return Some(LexicalScopeBinding::Res(Res::Err));
1830 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1831 // FIXME(jseyfried) improve `Self` hygiene
1832 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1833 (empty_span, empty_span)
1834 } else if ns == TypeNS {
1835 let normalized_span = ident.span.normalize_to_macros_2_0();
1836 (normalized_span, normalized_span)
1838 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1840 ident.span = general_span;
1841 let normalized_ident = Ident { span: normalized_span, ..ident };
1843 // Walk backwards up the ribs in scope.
1844 let record_used = record_used_id.is_some();
1845 let mut module = self.graph_root;
1846 for i in (0..ribs.len()).rev() {
1847 debug!("walk rib\n{:?}", ribs[i].bindings);
1848 // Use the rib kind to determine whether we are resolving parameters
1849 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1850 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1851 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1853 // The ident resolves to a type parameter or local variable.
1854 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1860 *original_rib_ident_def,
1865 module = match ribs[i].kind {
1866 ModuleRibKind(module) => module,
1867 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1868 // If an invocation of this macro created `ident`, give up on `ident`
1869 // and switch to `ident`'s source from the macro definition.
1870 ident.span.remove_mark();
1876 let item = self.resolve_ident_in_module_unadjusted(
1877 ModuleOrUniformRoot::Module(module),
1884 if let Ok(binding) = item {
1885 // The ident resolves to an item.
1886 return Some(LexicalScopeBinding::Item(binding));
1890 ModuleKind::Block(..) => {} // We can see through blocks
1895 ident = normalized_ident;
1896 let mut poisoned = None;
1898 let mut span_data = ident.span.data();
1899 let opt_module = if let Some(node_id) = record_used_id {
1900 self.hygienic_lexical_parent_with_compatibility_fallback(
1902 &mut span_data.ctxt,
1907 self.hygienic_lexical_parent(module, &mut span_data.ctxt)
1909 ident.span = span_data.span();
1910 module = unwrap_or!(opt_module, break);
1911 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1912 let result = self.resolve_ident_in_module_unadjusted(
1913 ModuleOrUniformRoot::Module(module),
1916 adjusted_parent_scope,
1923 if let Some(node_id) = poisoned {
1924 self.lint_buffer.buffer_lint_with_diagnostic(
1925 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1928 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1929 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(ident.span),
1932 return Some(LexicalScopeBinding::Item(binding));
1934 Err(Determined) => continue,
1935 Err(Undetermined) => {
1936 span_bug!(ident.span, "undetermined resolution during main resolution pass")
1941 if !module.no_implicit_prelude {
1942 ident.span.adjust(ExpnId::root());
1944 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1945 return Some(LexicalScopeBinding::Item(binding));
1947 if let Some(ident) = self.registered_tools.get(&ident) {
1949 (Res::ToolMod, ty::Visibility::Public, ident.span, ExpnId::root())
1950 .to_name_binding(self.arenas);
1951 return Some(LexicalScopeBinding::Item(binding));
1954 if let Some(prelude) = self.prelude {
1955 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1956 ModuleOrUniformRoot::Module(prelude),
1963 return Some(LexicalScopeBinding::Item(binding));
1969 if let Some(prim_ty) = PrimTy::from_name(ident.name) {
1971 (Res::PrimTy(prim_ty), ty::Visibility::Public, DUMMY_SP, ExpnId::root())
1972 .to_name_binding(self.arenas);
1973 return Some(LexicalScopeBinding::Item(binding));
1980 fn hygienic_lexical_parent(
1983 ctxt: &mut SyntaxContext,
1984 ) -> Option<Module<'a>> {
1985 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
1986 return Some(self.macro_def_scope(ctxt.remove_mark()));
1989 if let ModuleKind::Block(..) = module.kind {
1990 return Some(module.parent.unwrap().nearest_item_scope());
1996 fn hygienic_lexical_parent_with_compatibility_fallback(
1999 ctxt: &mut SyntaxContext,
2001 poisoned: &mut Option<NodeId>,
2002 ) -> Option<Module<'a>> {
2003 if let module @ Some(..) = self.hygienic_lexical_parent(module, ctxt) {
2007 // We need to support the next case under a deprecation warning
2010 // ---- begin: this comes from a proc macro derive
2011 // mod implementation_details {
2012 // // Note that `MyStruct` is not in scope here.
2013 // impl SomeTrait for MyStruct { ... }
2017 // So we have to fall back to the module's parent during lexical resolution in this case.
2018 if let Some(parent) = module.parent {
2019 // Inner module is inside the macro, parent module is outside of the macro.
2020 if module.expansion != parent.expansion
2021 && module.expansion.is_descendant_of(parent.expansion)
2023 // The macro is a proc macro derive
2024 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
2025 let ext = self.get_macro_by_def_id(def_id);
2026 if ext.builtin_name.is_none()
2027 && ext.macro_kind() == MacroKind::Derive
2028 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
2030 *poisoned = Some(node_id);
2031 return module.parent;
2040 fn resolve_ident_in_module(
2042 module: ModuleOrUniformRoot<'a>,
2045 parent_scope: &ParentScope<'a>,
2048 ) -> Result<&'a NameBinding<'a>, Determinacy> {
2049 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
2050 .map_err(|(determinacy, _)| determinacy)
2053 fn resolve_ident_in_module_ext(
2055 module: ModuleOrUniformRoot<'a>,
2058 parent_scope: &ParentScope<'a>,
2061 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2062 let tmp_parent_scope;
2063 let mut adjusted_parent_scope = parent_scope;
2065 ModuleOrUniformRoot::Module(m) => {
2066 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2068 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
2069 adjusted_parent_scope = &tmp_parent_scope;
2072 ModuleOrUniformRoot::ExternPrelude => {
2073 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2075 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2079 self.resolve_ident_in_module_unadjusted_ext(
2083 adjusted_parent_scope,
2090 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2091 debug!("resolve_crate_root({:?})", ident);
2092 let mut ctxt = ident.span.ctxt();
2093 let mark = if ident.name == kw::DollarCrate {
2094 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2095 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2096 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2097 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2098 // definitions actually produced by `macro` and `macro` definitions produced by
2099 // `macro_rules!`, but at least such configurations are not stable yet.
2100 ctxt = ctxt.normalize_to_macro_rules();
2102 "resolve_crate_root: marks={:?}",
2103 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2105 let mut iter = ctxt.marks().into_iter().rev().peekable();
2106 let mut result = None;
2107 // Find the last opaque mark from the end if it exists.
2108 while let Some(&(mark, transparency)) = iter.peek() {
2109 if transparency == Transparency::Opaque {
2110 result = Some(mark);
2117 "resolve_crate_root: found opaque mark {:?} {:?}",
2119 result.map(|r| r.expn_data())
2121 // Then find the last semi-transparent mark from the end if it exists.
2122 for (mark, transparency) in iter {
2123 if transparency == Transparency::SemiTransparent {
2124 result = Some(mark);
2130 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2132 result.map(|r| r.expn_data())
2136 debug!("resolve_crate_root: not DollarCrate");
2137 ctxt = ctxt.normalize_to_macros_2_0();
2138 ctxt.adjust(ExpnId::root())
2140 let module = match mark {
2141 Some(def) => self.macro_def_scope(def),
2144 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2147 return self.graph_root;
2150 let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.nearest_parent_mod });
2152 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2161 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2162 let mut module = self.get_module(module.nearest_parent_mod);
2163 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2164 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
2165 module = self.get_module(parent.nearest_parent_mod);
2173 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2174 parent_scope: &ParentScope<'a>,
2177 crate_lint: CrateLint,
2178 ) -> PathResult<'a> {
2179 self.resolve_path_with_ribs(
2190 fn resolve_path_with_ribs(
2193 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2194 parent_scope: &ParentScope<'a>,
2197 crate_lint: CrateLint,
2198 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2199 ) -> PathResult<'a> {
2200 let mut module = None;
2201 let mut allow_super = true;
2202 let mut second_binding = None;
2205 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2206 path_span={:?}, crate_lint={:?})",
2207 path, opt_ns, record_used, path_span, crate_lint,
2210 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2211 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2212 let record_segment_res = |this: &mut Self, res| {
2214 if let Some(id) = id {
2215 if !this.partial_res_map.contains_key(&id) {
2216 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2217 this.record_partial_res(id, PartialRes::new(res));
2223 let is_last = i == path.len() - 1;
2224 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2225 let name = ident.name;
2227 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2230 if allow_super && name == kw::Super {
2231 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2232 let self_module = match i {
2233 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2235 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2239 if let Some(self_module) = self_module {
2240 if let Some(parent) = self_module.parent {
2241 module = Some(ModuleOrUniformRoot::Module(
2242 self.resolve_self(&mut ctxt, parent),
2247 let msg = "there are too many leading `super` keywords".to_string();
2248 return PathResult::Failed {
2252 is_error_from_last_segment: false,
2256 if name == kw::SelfLower {
2257 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2258 module = Some(ModuleOrUniformRoot::Module(
2259 self.resolve_self(&mut ctxt, parent_scope.module),
2263 if name == kw::PathRoot && ident.span.rust_2018() {
2264 module = Some(ModuleOrUniformRoot::ExternPrelude);
2267 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2268 // `::a::b` from 2015 macro on 2018 global edition
2269 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2272 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2273 // `::a::b`, `crate::a::b` or `$crate::a::b`
2274 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2280 // Report special messages for path segment keywords in wrong positions.
2281 if ident.is_path_segment_keyword() && i != 0 {
2282 let name_str = if name == kw::PathRoot {
2283 "crate root".to_string()
2285 format!("`{}`", name)
2287 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2288 format!("global paths cannot start with {}", name_str)
2290 format!("{} in paths can only be used in start position", name_str)
2292 return PathResult::Failed {
2296 is_error_from_last_segment: false,
2300 enum FindBindingResult<'a> {
2301 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2302 PathResult(PathResult<'a>),
2304 let find_binding_in_ns = |this: &mut Self, ns| {
2305 let binding = if let Some(module) = module {
2306 this.resolve_ident_in_module(
2314 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2315 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2316 this.early_resolve_ident_in_lexical_scope(
2325 let record_used_id = if record_used {
2326 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2330 match this.resolve_ident_in_lexical_scope(
2338 // we found a locally-imported or available item/module
2339 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2340 // we found a local variable or type param
2341 Some(LexicalScopeBinding::Res(res))
2342 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2344 record_segment_res(this, res);
2345 return FindBindingResult::PathResult(PathResult::NonModule(
2346 PartialRes::with_unresolved_segments(res, path.len() - 1),
2349 _ => Err(Determinacy::determined(record_used)),
2352 FindBindingResult::Binding(binding)
2354 let binding = match find_binding_in_ns(self, ns) {
2355 FindBindingResult::PathResult(x) => return x,
2356 FindBindingResult::Binding(binding) => binding,
2361 second_binding = Some(binding);
2363 let res = binding.res();
2364 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2365 if let Some(next_module) = binding.module() {
2366 module = Some(ModuleOrUniformRoot::Module(next_module));
2367 record_segment_res(self, res);
2368 } else if res == Res::ToolMod && i + 1 != path.len() {
2369 if binding.is_import() {
2373 "cannot use a tool module through an import",
2375 .span_note(binding.span, "the tool module imported here")
2378 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2379 return PathResult::NonModule(PartialRes::new(res));
2380 } else if res == Res::Err {
2381 return PathResult::NonModule(PartialRes::new(Res::Err));
2382 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2383 self.lint_if_path_starts_with_module(
2389 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2394 let label = format!(
2395 "`{}` is {} {}, not a module",
2401 return PathResult::Failed {
2405 is_error_from_last_segment: is_last,
2409 Err(Undetermined) => return PathResult::Indeterminate,
2410 Err(Determined) => {
2411 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2412 if opt_ns.is_some() && !module.is_normal() {
2413 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2414 module.res().unwrap(),
2419 let module_res = match module {
2420 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2423 let (label, suggestion) = if module_res == self.graph_root.res() {
2424 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2425 // Don't look up import candidates if this is a speculative resolve
2426 let mut candidates = if record_used {
2427 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2431 candidates.sort_by_cached_key(|c| {
2432 (c.path.segments.len(), pprust::path_to_string(&c.path))
2434 if let Some(candidate) = candidates.get(0) {
2436 String::from("unresolved import"),
2438 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2439 String::from("a similar path exists"),
2440 Applicability::MaybeIncorrect,
2443 } else if self.session.edition() == Edition::Edition2015 {
2444 (format!("maybe a missing crate `{}`?", ident), None)
2446 (format!("could not find `{}` in the crate root", ident), None)
2454 .map_or(false, |c| c.is_ascii_uppercase())
2456 (format!("use of undeclared type `{}`", ident), None)
2458 (format!("use of undeclared crate or module `{}`", ident), None)
2461 let parent = path[i - 1].ident.name;
2462 let parent = match parent {
2463 // ::foo is mounted at the crate root for 2015, and is the extern
2464 // prelude for 2018+
2465 kw::PathRoot if self.session.edition() > Edition::Edition2015 => {
2466 "the list of imported crates".to_owned()
2468 kw::PathRoot | kw::Crate => "the crate root".to_owned(),
2470 format!("`{}`", parent)
2474 let mut msg = format!("could not find `{}` in {}", ident, parent);
2475 if ns == TypeNS || ns == ValueNS {
2476 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2477 if let FindBindingResult::Binding(Ok(binding)) =
2478 find_binding_in_ns(self, ns_to_try)
2480 let mut found = |what| {
2482 "expected {}, found {} `{}` in {}",
2489 if binding.module().is_some() {
2492 match binding.res() {
2493 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2494 _ => found(ns_to_try.descr()),
2501 return PathResult::Failed {
2505 is_error_from_last_segment: is_last,
2511 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2513 PathResult::Module(match module {
2514 Some(module) => module,
2515 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2516 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2520 fn lint_if_path_starts_with_module(
2522 crate_lint: CrateLint,
2525 second_binding: Option<&NameBinding<'_>>,
2527 let (diag_id, diag_span) = match crate_lint {
2528 CrateLint::No => return,
2529 CrateLint::SimplePath(id) => (id, path_span),
2530 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2531 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2534 let first_name = match path.get(0) {
2535 // In the 2018 edition this lint is a hard error, so nothing to do
2536 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2540 // We're only interested in `use` paths which should start with
2541 // `{{root}}` currently.
2542 if first_name != kw::PathRoot {
2547 // If this import looks like `crate::...` it's already good
2548 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2549 // Otherwise go below to see if it's an extern crate
2551 // If the path has length one (and it's `PathRoot` most likely)
2552 // then we don't know whether we're gonna be importing a crate or an
2553 // item in our crate. Defer this lint to elsewhere
2557 // If the first element of our path was actually resolved to an
2558 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2559 // warning, this looks all good!
2560 if let Some(binding) = second_binding {
2561 if let NameBindingKind::Import { import, .. } = binding.kind {
2562 // Careful: we still want to rewrite paths from renamed extern crates.
2563 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2569 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2570 self.lint_buffer.buffer_lint_with_diagnostic(
2571 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2574 "absolute paths must start with `self`, `super`, \
2575 `crate`, or an external crate name in the 2018 edition",
2580 // Validate a local resolution (from ribs).
2581 fn validate_res_from_ribs(
2588 original_rib_ident_def: Ident,
2589 all_ribs: &[Rib<'a>],
2591 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2592 debug!("validate_res_from_ribs({:?})", res);
2593 let ribs = &all_ribs[rib_index + 1..];
2595 // An invalid forward use of a generic parameter from a previous default.
2596 if let ForwardGenericParamBanRibKind = all_ribs[rib_index].kind {
2598 let res_error = if rib_ident.name == kw::SelfUpper {
2599 ResolutionError::SelfInTyParamDefault
2601 ResolutionError::ForwardDeclaredTyParam
2603 self.report_error(span, res_error);
2605 assert_eq!(res, Res::Err);
2611 use ResolutionError::*;
2612 let mut res_err = None;
2617 | ClosureOrAsyncRibKind
2619 | MacroDefinition(..)
2620 | ForwardGenericParamBanRibKind => {
2621 // Nothing to do. Continue.
2623 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2624 // This was an attempt to access an upvar inside a
2625 // named function item. This is not allowed, so we
2628 // We don't immediately trigger a resolve error, because
2629 // we want certain other resolution errors (namely those
2630 // emitted for `ConstantItemRibKind` below) to take
2632 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2635 ConstantItemRibKind(_, item) => {
2636 // Still doesn't deal with upvars
2638 let (span, resolution_error) =
2639 if let Some((ident, constant_item_kind)) = item {
2640 let kind_str = match constant_item_kind {
2641 ConstantItemKind::Const => "const",
2642 ConstantItemKind::Static => "static",
2646 AttemptToUseNonConstantValueInConstant(
2647 ident, "let", kind_str,
2653 AttemptToUseNonConstantValueInConstant(
2654 original_rib_ident_def,
2660 self.report_error(span, resolution_error);
2664 ConstParamTyRibKind => {
2666 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2672 if let Some(res_err) = res_err {
2673 self.report_error(span, res_err);
2677 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2678 let mut in_ty_param_default = false;
2680 let has_generic_params = match rib.kind {
2682 | ClosureOrAsyncRibKind
2685 | MacroDefinition(..) => {
2686 // Nothing to do. Continue.
2690 // We only forbid constant items if we are inside of type defaults,
2691 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2692 ForwardGenericParamBanRibKind => {
2693 // FIXME(const_generic_defaults): we may need to distinguish between
2694 // being in type parameter defaults and const parameter defaults
2695 in_ty_param_default = true;
2698 ConstantItemRibKind(trivial, _) => {
2699 let features = self.session.features_untracked();
2700 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2702 || features.const_generics
2703 || features.lazy_normalization_consts)
2705 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2706 // we can't easily tell if it's generic at this stage, so we instead remember
2707 // this and then enforce the self type to be concrete later on.
2708 if let Res::SelfTy(trait_def, Some((impl_def, _))) = res {
2709 res = Res::SelfTy(trait_def, Some((impl_def, true)));
2714 ResolutionError::ParamInNonTrivialAnonConst {
2715 name: rib_ident.name,
2721 self.session.delay_span_bug(span, CG_BUG_STR);
2726 if in_ty_param_default {
2730 ResolutionError::ParamInAnonConstInTyDefault(
2741 // This was an attempt to use a type parameter outside its scope.
2742 ItemRibKind(has_generic_params) => has_generic_params,
2743 FnItemRibKind => HasGenericParams::Yes,
2744 ConstParamTyRibKind => {
2748 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2758 ResolutionError::GenericParamsFromOuterFunction(
2767 Res::Def(DefKind::ConstParam, _) => {
2768 let mut ribs = ribs.iter().peekable();
2769 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2770 // When declaring const parameters inside function signatures, the first rib
2771 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2772 // (spuriously) conflicting with the const param.
2776 let mut in_ty_param_default = false;
2778 let has_generic_params = match rib.kind {
2780 | ClosureOrAsyncRibKind
2783 | MacroDefinition(..) => continue,
2785 // We only forbid constant items if we are inside of type defaults,
2786 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2787 ForwardGenericParamBanRibKind => {
2788 // FIXME(const_generic_defaults): we may need to distinguish between
2789 // being in type parameter defaults and const parameter defaults
2790 in_ty_param_default = true;
2793 ConstantItemRibKind(trivial, _) => {
2794 let features = self.session.features_untracked();
2795 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2797 || features.const_generics
2798 || features.lazy_normalization_consts)
2803 ResolutionError::ParamInNonTrivialAnonConst {
2804 name: rib_ident.name,
2810 self.session.delay_span_bug(span, CG_BUG_STR);
2814 if in_ty_param_default {
2818 ResolutionError::ParamInAnonConstInTyDefault(
2829 ItemRibKind(has_generic_params) => has_generic_params,
2830 FnItemRibKind => HasGenericParams::Yes,
2831 ConstParamTyRibKind => {
2835 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2842 // This was an attempt to use a const parameter outside its scope.
2846 ResolutionError::GenericParamsFromOuterFunction(
2860 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2861 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2862 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2863 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2867 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2868 vis.is_accessible_from(module.nearest_parent_mod, self)
2871 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2872 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2873 if !ptr::eq(module, old_module) {
2874 span_bug!(binding.span, "parent module is reset for binding");
2879 fn disambiguate_macro_rules_vs_modularized(
2881 macro_rules: &'a NameBinding<'a>,
2882 modularized: &'a NameBinding<'a>,
2884 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2885 // is disambiguated to mitigate regressions from macro modularization.
2886 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2888 self.binding_parent_modules.get(&PtrKey(macro_rules)),
2889 self.binding_parent_modules.get(&PtrKey(modularized)),
2891 (Some(macro_rules), Some(modularized)) => {
2892 macro_rules.nearest_parent_mod == modularized.nearest_parent_mod
2893 && modularized.is_ancestor_of(macro_rules)
2899 fn report_errors(&mut self, krate: &Crate) {
2900 self.report_with_use_injections(krate);
2902 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2903 let msg = "macro-expanded `macro_export` macros from the current crate \
2904 cannot be referred to by absolute paths";
2905 self.lint_buffer.buffer_lint_with_diagnostic(
2906 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2910 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2914 for ambiguity_error in &self.ambiguity_errors {
2915 self.report_ambiguity_error(ambiguity_error);
2918 let mut reported_spans = FxHashSet::default();
2919 for error in &self.privacy_errors {
2920 if reported_spans.insert(error.dedup_span) {
2921 self.report_privacy_error(error);
2926 fn report_with_use_injections(&mut self, krate: &Crate) {
2927 for UseError { mut err, candidates, def_id, instead, suggestion } in
2928 self.use_injections.drain(..)
2930 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
2931 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
2935 if !candidates.is_empty() {
2936 diagnostics::show_candidates(&mut err, span, &candidates, instead, found_use);
2937 } else if let Some((span, msg, sugg, appl)) = suggestion {
2938 err.span_suggestion(span, msg, sugg, appl);
2944 fn report_conflict<'b>(
2949 new_binding: &NameBinding<'b>,
2950 old_binding: &NameBinding<'b>,
2952 // Error on the second of two conflicting names
2953 if old_binding.span.lo() > new_binding.span.lo() {
2954 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2957 let container = match parent.kind {
2958 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id().unwrap()),
2959 ModuleKind::Block(..) => "block",
2962 let old_noun = match old_binding.is_import() {
2964 false => "definition",
2967 let new_participle = match new_binding.is_import() {
2973 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
2975 if let Some(s) = self.name_already_seen.get(&name) {
2981 let old_kind = match (ns, old_binding.module()) {
2982 (ValueNS, _) => "value",
2983 (MacroNS, _) => "macro",
2984 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2985 (TypeNS, Some(module)) if module.is_normal() => "module",
2986 (TypeNS, Some(module)) if module.is_trait() => "trait",
2987 (TypeNS, _) => "type",
2990 let msg = format!("the name `{}` is defined multiple times", name);
2992 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2993 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2994 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2995 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2996 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2998 _ => match (old_binding.is_import(), new_binding.is_import()) {
2999 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3000 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3001 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3006 "`{}` must be defined only once in the {} namespace of this {}",
3012 err.span_label(span, format!("`{}` re{} here", name, new_participle));
3014 self.session.source_map().guess_head_span(old_binding.span),
3015 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
3018 // See https://github.com/rust-lang/rust/issues/32354
3019 use NameBindingKind::Import;
3020 let import = match (&new_binding.kind, &old_binding.kind) {
3021 // If there are two imports where one or both have attributes then prefer removing the
3022 // import without attributes.
3023 (Import { import: new, .. }, Import { import: old, .. })
3025 !new_binding.span.is_dummy()
3026 && !old_binding.span.is_dummy()
3027 && (new.has_attributes || old.has_attributes)
3030 if old.has_attributes {
3031 Some((new, new_binding.span, true))
3033 Some((old, old_binding.span, true))
3036 // Otherwise prioritize the new binding.
3037 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
3038 Some((import, new_binding.span, other.is_import()))
3040 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
3041 Some((import, old_binding.span, other.is_import()))
3046 // Check if the target of the use for both bindings is the same.
3047 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
3048 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
3050 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
3051 // Only suggest removing an import if both bindings are to the same def, if both spans
3052 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
3053 // been introduced by a item.
3054 let should_remove_import = duplicate
3056 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
3059 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3060 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3062 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3063 // Simple case - remove the entire import. Due to the above match arm, this can
3064 // only be a single use so just remove it entirely.
3065 err.tool_only_span_suggestion(
3066 import.use_span_with_attributes,
3067 "remove unnecessary import",
3069 Applicability::MaybeIncorrect,
3072 Some((import, span, _)) => {
3073 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3079 self.name_already_seen.insert(name, span);
3082 /// This function adds a suggestion to change the binding name of a new import that conflicts
3083 /// with an existing import.
3085 /// ```text,ignore (diagnostic)
3086 /// help: you can use `as` to change the binding name of the import
3088 /// LL | use foo::bar as other_bar;
3089 /// | ^^^^^^^^^^^^^^^^^^^^^
3091 fn add_suggestion_for_rename_of_use(
3093 err: &mut DiagnosticBuilder<'_>,
3095 import: &Import<'_>,
3098 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3099 format!("Other{}", name)
3101 format!("other_{}", name)
3104 let mut suggestion = None;
3106 ImportKind::Single { type_ns_only: true, .. } => {
3107 suggestion = Some(format!("self as {}", suggested_name))
3109 ImportKind::Single { source, .. } => {
3111 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3113 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3114 if pos <= snippet.len() {
3115 suggestion = Some(format!(
3119 if snippet.ends_with(';') { ";" } else { "" }
3125 ImportKind::ExternCrate { source, target, .. } => {
3126 suggestion = Some(format!(
3127 "extern crate {} as {};",
3128 source.unwrap_or(target.name),
3132 _ => unreachable!(),
3135 let rename_msg = "you can use `as` to change the binding name of the import";
3136 if let Some(suggestion) = suggestion {
3137 err.span_suggestion(
3141 Applicability::MaybeIncorrect,
3144 err.span_label(binding_span, rename_msg);
3148 /// This function adds a suggestion to remove a unnecessary binding from an import that is
3149 /// nested. In the following example, this function will be invoked to remove the `a` binding
3150 /// in the second use statement:
3152 /// ```ignore (diagnostic)
3153 /// use issue_52891::a;
3154 /// use issue_52891::{d, a, e};
3157 /// The following suggestion will be added:
3159 /// ```ignore (diagnostic)
3160 /// use issue_52891::{d, a, e};
3161 /// ^-- help: remove unnecessary import
3164 /// If the nested use contains only one import then the suggestion will remove the entire
3167 /// It is expected that the provided import is nested - this isn't checked by the
3168 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3169 /// as characters expected by span manipulations won't be present.
3170 fn add_suggestion_for_duplicate_nested_use(
3172 err: &mut DiagnosticBuilder<'_>,
3173 import: &Import<'_>,
3176 assert!(import.is_nested());
3177 let message = "remove unnecessary import";
3179 // Two examples will be used to illustrate the span manipulations we're doing:
3181 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3182 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3183 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3184 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3186 let (found_closing_brace, span) =
3187 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3189 // If there was a closing brace then identify the span to remove any trailing commas from
3190 // previous imports.
3191 if found_closing_brace {
3192 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3193 err.tool_only_span_suggestion(
3197 Applicability::MaybeIncorrect,
3200 // Remove the entire line if we cannot extend the span back, this indicates a
3201 // `issue_52891::{self}` case.
3202 err.span_suggestion(
3203 import.use_span_with_attributes,
3206 Applicability::MaybeIncorrect,
3213 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3216 fn extern_prelude_get(
3220 ) -> Option<&'a NameBinding<'a>> {
3221 if ident.is_path_segment_keyword() {
3222 // Make sure `self`, `super` etc produce an error when passed to here.
3225 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3226 if let Some(binding) = entry.extern_crate_item {
3227 if !speculative && entry.introduced_by_item {
3228 self.record_use(ident, TypeNS, binding, false);
3232 let crate_id = if !speculative {
3233 self.crate_loader.process_path_extern(ident.name, ident.span)
3235 self.crate_loader.maybe_process_path_extern(ident.name)?
3237 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
3239 (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
3240 .to_name_binding(self.arenas),
3246 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3247 /// isn't something that can be returned because it can't be made to live that long,
3248 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3249 /// just that an error occurred.
3250 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3251 pub fn resolve_str_path_error(
3257 ) -> Result<(ast::Path, Res), ()> {
3258 let path = if path_str.starts_with("::") {
3261 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3262 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3263 .map(|i| self.new_ast_path_segment(i))
3272 .map(Ident::from_str)
3273 .map(|i| self.new_ast_path_segment(i))
3278 let module = self.get_module(module_id);
3279 let parent_scope = &ParentScope::module(module, self);
3280 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3284 // Resolve a path passed from rustdoc or HIR lowering.
3285 fn resolve_ast_path(
3289 parent_scope: &ParentScope<'a>,
3290 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3291 match self.resolve_path(
3292 &Segment::from_path(path),
3299 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3300 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3301 Ok(path_res.base_res())
3303 PathResult::NonModule(..) => Err((
3305 ResolutionError::FailedToResolve {
3306 label: String::from("type-relative paths are not supported in this context"),
3310 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3311 PathResult::Failed { span, label, suggestion, .. } => {
3312 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3317 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3318 let mut seg = ast::PathSegment::from_ident(ident);
3319 seg.id = self.next_node_id();
3324 pub fn graph_root(&self) -> Module<'a> {
3329 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3333 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3335 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3336 if let Some(def_id) = def_id.as_local() { Some(self.def_id_to_span[def_id]) } else { None }
3339 /// Checks if an expression refers to a function marked with
3340 /// `#[rustc_legacy_const_generics]` and returns the argument index list
3341 /// from the attribute.
3342 pub fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
3343 if let ExprKind::Path(None, path) = &expr.kind {
3344 // Don't perform legacy const generics rewriting if the path already
3345 // has generic arguments.
3346 if path.segments.last().unwrap().args.is_some() {
3350 let partial_res = self.partial_res_map.get(&expr.id)?;
3351 if partial_res.unresolved_segments() != 0 {
3355 if let Res::Def(def::DefKind::Fn, def_id) = partial_res.base_res() {
3356 // We only support cross-crate argument rewriting. Uses
3357 // within the same crate should be updated to use the new
3358 // const generics style.
3359 if def_id.is_local() {
3363 if let Some(v) = self.legacy_const_generic_args.get(&def_id) {
3367 let parse_attrs = || {
3368 let attrs = self.cstore().item_attrs(def_id, self.session);
3371 .find(|a| self.session.check_name(a, sym::rustc_legacy_const_generics))?;
3372 let mut ret = vec![];
3373 for meta in attr.meta_item_list()? {
3374 match meta.literal()?.kind {
3375 LitKind::Int(a, _) => {
3376 ret.push(a as usize);
3378 _ => panic!("invalid arg index"),
3384 // Cache the lookup to avoid parsing attributes for an iterm
3386 let ret = parse_attrs();
3387 self.legacy_const_generic_args.insert(def_id, ret.clone());
3395 fn names_to_string(names: &[Symbol]) -> String {
3396 let mut result = String::new();
3397 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3399 result.push_str("::");
3401 if Ident::with_dummy_span(*name).is_raw_guess() {
3402 result.push_str("r#");
3404 result.push_str(&name.as_str());
3409 fn path_names_to_string(path: &Path) -> String {
3410 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3413 /// A somewhat inefficient routine to obtain the name of a module.
3414 fn module_to_string(module: Module<'_>) -> Option<String> {
3415 let mut names = Vec::new();
3417 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3418 if let ModuleKind::Def(.., name) = module.kind {
3419 if let Some(parent) = module.parent {
3421 collect_mod(names, parent);
3424 names.push(Symbol::intern("<opaque>"));
3425 collect_mod(names, module.parent.unwrap());
3428 collect_mod(&mut names, module);
3430 if names.is_empty() {
3434 Some(names_to_string(&names))
3437 #[derive(Copy, Clone, Debug)]
3439 /// Do not issue the lint.
3442 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3443 /// In this case, we can take the span of that path.
3446 /// This lint comes from a `use` statement. In this case, what we
3447 /// care about really is the *root* `use` statement; e.g., if we
3448 /// have nested things like `use a::{b, c}`, we care about the
3450 UsePath { root_id: NodeId, root_span: Span },
3452 /// This is the "trait item" from a fully qualified path. For example,
3453 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3454 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3455 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3459 fn node_id(&self) -> Option<NodeId> {
3461 CrateLint::No => None,
3462 CrateLint::SimplePath(id)
3463 | CrateLint::UsePath { root_id: id, .. }
3464 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3469 pub fn provide(providers: &mut Providers) {
3470 late::lifetimes::provide(providers);