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(crate_visibility_modifier)]
15 #![feature(format_args_capture)]
17 #![feature(or_patterns)]
18 #![recursion_limit = "256"]
20 pub use rustc_hir::def::{Namespace, PerNS};
24 use rustc_arena::{DroplessArena, TypedArena};
25 use rustc_ast::node_id::NodeMap;
26 use rustc_ast::unwrap_or;
27 use rustc_ast::visit::{self, Visitor};
28 use rustc_ast::{self as ast, NodeId};
29 use rustc_ast::{Crate, CRATE_NODE_ID};
30 use rustc_ast::{ItemKind, Path};
31 use rustc_ast_lowering::ResolverAstLowering;
32 use rustc_ast_pretty::pprust;
33 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
34 use rustc_data_structures::ptr_key::PtrKey;
35 use rustc_data_structures::sync::Lrc;
36 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
37 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
38 use rustc_hir::def::Namespace::*;
39 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
40 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
41 use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
42 use rustc_hir::{PrimTy, TraitCandidate};
43 use rustc_index::vec::IndexVec;
44 use rustc_metadata::creader::{CStore, CrateLoader};
45 use rustc_middle::hir::exports::ExportMap;
46 use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn};
47 use rustc_middle::span_bug;
48 use rustc_middle::ty::query::Providers;
49 use rustc_middle::ty::{self, DefIdTree, ResolverOutputs};
50 use rustc_session::lint;
51 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
52 use rustc_session::Session;
53 use rustc_span::edition::Edition;
54 use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency};
55 use rustc_span::source_map::Spanned;
56 use rustc_span::symbol::{kw, sym, Ident, Symbol};
57 use rustc_span::{Span, DUMMY_SP};
59 use smallvec::{smallvec, SmallVec};
60 use std::cell::{Cell, RefCell};
61 use std::collections::BTreeSet;
62 use std::{cmp, fmt, iter, ptr};
65 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
66 use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion};
67 use imports::{Import, ImportKind, ImportResolver, NameResolution};
68 use late::{ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind::*};
69 use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
71 type Res = def::Res<NodeId>;
73 mod build_reduced_graph;
86 #[derive(Copy, Clone, PartialEq, Debug)]
87 pub enum Determinacy {
93 fn determined(determined: bool) -> Determinacy {
94 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
98 /// A specific scope in which a name can be looked up.
99 /// This enum is currently used only for early resolution (imports and macros),
100 /// but not for late resolution yet.
101 #[derive(Clone, Copy)]
103 DeriveHelpers(ExpnId),
105 MacroRules(MacroRulesScopeRef<'a>),
117 /// Names from different contexts may want to visit different subsets of all specific scopes
118 /// with different restrictions when looking up the resolution.
119 /// This enum is currently used only for early resolution (imports and macros),
120 /// but not for late resolution yet.
122 /// All scopes with the given namespace.
123 All(Namespace, /*is_import*/ bool),
124 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
125 AbsolutePath(Namespace),
126 /// All scopes with macro namespace and the given macro kind restriction.
130 /// Everything you need to know about a name's location to resolve it.
131 /// Serves as a starting point for the scope visitor.
132 /// This struct is currently used only for early resolution (imports and macros),
133 /// but not for late resolution yet.
134 #[derive(Clone, Copy, Debug)]
135 pub struct ParentScope<'a> {
138 macro_rules: MacroRulesScopeRef<'a>,
139 derives: &'a [ast::Path],
142 impl<'a> ParentScope<'a> {
143 /// Creates a parent scope with the passed argument used as the module scope component,
144 /// and other scope components set to default empty values.
145 pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> {
148 expansion: ExpnId::root(),
149 macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty),
156 struct BindingError {
158 origin: BTreeSet<Span>,
159 target: BTreeSet<Span>,
163 impl PartialOrd for BindingError {
164 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
165 Some(self.cmp(other))
169 impl PartialEq for BindingError {
170 fn eq(&self, other: &BindingError) -> bool {
171 self.name == other.name
175 impl Ord for BindingError {
176 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
177 self.name.cmp(&other.name)
181 enum ResolutionError<'a> {
182 /// Error E0401: can't use type or const parameters from outer function.
183 GenericParamsFromOuterFunction(Res, HasGenericParams),
184 /// Error E0403: the name is already used for a type or const parameter in this generic
186 NameAlreadyUsedInParameterList(Symbol, Span),
187 /// Error E0407: method is not a member of trait.
188 MethodNotMemberOfTrait(Symbol, &'a str),
189 /// Error E0437: type is not a member of trait.
190 TypeNotMemberOfTrait(Symbol, &'a str),
191 /// Error E0438: const is not a member of trait.
192 ConstNotMemberOfTrait(Symbol, &'a str),
193 /// Error E0408: variable `{}` is not bound in all patterns.
194 VariableNotBoundInPattern(&'a BindingError),
195 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
196 VariableBoundWithDifferentMode(Symbol, Span),
197 /// Error E0415: identifier is bound more than once in this parameter list.
198 IdentifierBoundMoreThanOnceInParameterList(Symbol),
199 /// Error E0416: identifier is bound more than once in the same pattern.
200 IdentifierBoundMoreThanOnceInSamePattern(Symbol),
201 /// Error E0426: use of undeclared label.
202 UndeclaredLabel { name: Symbol, suggestion: Option<LabelSuggestion> },
203 /// Error E0429: `self` imports are only allowed within a `{ }` list.
204 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
205 /// Error E0430: `self` import can only appear once in the list.
206 SelfImportCanOnlyAppearOnceInTheList,
207 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
208 SelfImportOnlyInImportListWithNonEmptyPrefix,
209 /// Error E0433: failed to resolve.
210 FailedToResolve { label: String, suggestion: Option<Suggestion> },
211 /// Error E0434: can't capture dynamic environment in a fn item.
212 CannotCaptureDynamicEnvironmentInFnItem,
213 /// Error E0435: attempt to use a non-constant value in a constant.
214 AttemptToUseNonConstantValueInConstant(
216 /* suggestion */ &'static str,
217 /* current */ &'static str,
219 /// Error E0530: `X` bindings cannot shadow `Y`s.
220 BindingShadowsSomethingUnacceptable(&'static str, Symbol, &'a NameBinding<'a>),
221 /// Error E0128: type parameters with a default cannot use forward-declared identifiers.
222 ForwardDeclaredTyParam, // FIXME(const_generics_defaults)
223 /// ERROR E0770: the type of const parameters must not depend on other generic parameters.
224 ParamInTyOfConstParam(Symbol),
225 /// constant values inside of type parameter defaults must not depend on generic parameters.
226 ParamInAnonConstInTyDefault(Symbol),
227 /// generic parameters must not be used inside const evaluations.
229 /// This error is only emitted when using `min_const_generics`.
230 ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
231 /// Error E0735: type parameters with a default cannot use `Self`
232 SelfInTyParamDefault,
233 /// Error E0767: use of unreachable label
234 UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
237 enum VisResolutionError<'a> {
238 Relative2018(Span, &'a ast::Path),
240 FailedToResolve(Span, String, Option<Suggestion>),
241 ExpectedFound(Span, String, Res),
246 /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path
247 /// segments' which don't have the rest of an AST or HIR `PathSegment`.
248 #[derive(Clone, Copy, Debug)]
252 /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing
253 /// nonsensical suggestions.
254 has_generic_args: bool,
258 fn from_path(path: &Path) -> Vec<Segment> {
259 path.segments.iter().map(|s| s.into()).collect()
262 fn from_ident(ident: Ident) -> Segment {
263 Segment { ident, id: None, has_generic_args: false }
266 fn names_to_string(segments: &[Segment]) -> String {
267 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
271 impl<'a> From<&'a ast::PathSegment> for Segment {
272 fn from(seg: &'a ast::PathSegment) -> Segment {
273 Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() }
277 struct UsePlacementFinder {
278 target_module: NodeId,
283 impl UsePlacementFinder {
284 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
285 let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
286 visit::walk_crate(&mut finder, krate);
287 (finder.span, finder.found_use)
291 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
294 module: &'tcx ast::Mod,
296 _: &[ast::Attribute],
299 if self.span.is_some() {
302 if node_id != self.target_module {
303 visit::walk_mod(self, module);
306 // find a use statement
307 for item in &module.items {
309 ItemKind::Use(..) => {
310 // don't suggest placing a use before the prelude
311 // import or other generated ones
312 if !item.span.from_expansion() {
313 self.span = Some(item.span.shrink_to_lo());
314 self.found_use = true;
318 // don't place use before extern crate
319 ItemKind::ExternCrate(_) => {}
320 // but place them before the first other item
322 if self.span.map_or(true, |span| item.span < span)
323 && !item.span.from_expansion()
325 // don't insert between attributes and an item
326 if item.attrs.is_empty() {
327 self.span = Some(item.span.shrink_to_lo());
329 // find the first attribute on the item
330 for attr in &item.attrs {
331 if self.span.map_or(true, |span| attr.span < span) {
332 self.span = Some(attr.span.shrink_to_lo());
343 /// An intermediate resolution result.
345 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
346 /// items are visible in their whole block, while `Res`es only from the place they are defined
349 enum LexicalScopeBinding<'a> {
350 Item(&'a NameBinding<'a>),
354 impl<'a> LexicalScopeBinding<'a> {
355 fn res(self) -> Res {
357 LexicalScopeBinding::Item(binding) => binding.res(),
358 LexicalScopeBinding::Res(res) => res,
363 #[derive(Copy, Clone, Debug)]
364 enum ModuleOrUniformRoot<'a> {
368 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
369 CrateRootAndExternPrelude,
371 /// Virtual module that denotes resolution in extern prelude.
372 /// Used for paths starting with `::` on 2018 edition.
375 /// Virtual module that denotes resolution in current scope.
376 /// Used only for resolving single-segment imports. The reason it exists is that import paths
377 /// are always split into two parts, the first of which should be some kind of module.
381 impl ModuleOrUniformRoot<'_> {
382 fn same_def(lhs: Self, rhs: Self) -> bool {
384 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
385 lhs.def_id() == rhs.def_id()
388 ModuleOrUniformRoot::CrateRootAndExternPrelude,
389 ModuleOrUniformRoot::CrateRootAndExternPrelude,
391 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
392 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
398 #[derive(Clone, Debug)]
399 enum PathResult<'a> {
400 Module(ModuleOrUniformRoot<'a>),
401 NonModule(PartialRes),
406 suggestion: Option<Suggestion>,
407 is_error_from_last_segment: bool,
413 /// An anonymous module; e.g., just a block.
418 /// { // This is an anonymous module
419 /// f(); // This resolves to (2) as we are inside the block.
422 /// f(); // Resolves to (1)
426 /// Any module with a name.
430 /// * A normal module – either `mod from_file;` or `mod from_block { }` –
431 /// or the crate root (which is conceptually a top-level module).
432 /// Note that the crate root's [name][Self::name] will be [`kw::Empty`].
433 /// * A trait or an enum (it implicitly contains associated types, methods and variant
435 Def(DefKind, DefId, Symbol),
439 /// Get name of the module.
440 pub fn name(&self) -> Option<Symbol> {
442 ModuleKind::Block(..) => None,
443 ModuleKind::Def(.., name) => Some(*name),
448 /// A key that identifies a binding in a given `Module`.
450 /// Multiple bindings in the same module can have the same key (in a valid
451 /// program) if all but one of them come from glob imports.
452 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
454 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
458 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
459 /// `_` in the expanded AST that introduced this binding.
463 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
465 /// One node in the tree of modules.
467 /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these:
470 /// * crate root (aka, top-level anonymous module)
473 /// * curly-braced block with statements
475 /// You can use [`ModuleData::kind`] to determine the kind of module this is.
476 pub struct ModuleData<'a> {
477 /// The direct parent module (it may not be a `mod`, however).
478 parent: Option<Module<'a>>,
479 /// What kind of module this is, because this may not be a `mod`.
482 /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module).
483 /// This may be the crate root.
484 nearest_parent_mod: DefId,
486 /// Mapping between names and their (possibly in-progress) resolutions in this module.
487 /// Resolutions in modules from other crates are not populated until accessed.
488 lazy_resolutions: Resolutions<'a>,
489 /// True if this is a module from other crate that needs to be populated on access.
490 populate_on_access: Cell<bool>,
492 /// Macro invocations that can expand into items in this module.
493 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
495 /// Whether `#[no_implicit_prelude]` is active.
496 no_implicit_prelude: bool,
498 glob_importers: RefCell<Vec<&'a Import<'a>>>,
499 globs: RefCell<Vec<&'a Import<'a>>>,
501 /// Used to memoize the traits in this module for faster searches through all traits in scope.
502 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
504 /// Span of the module itself. Used for error reporting.
510 type Module<'a> = &'a ModuleData<'a>;
512 impl<'a> ModuleData<'a> {
514 parent: Option<Module<'a>>,
516 nearest_parent_mod: DefId,
524 lazy_resolutions: Default::default(),
525 populate_on_access: Cell::new(!nearest_parent_mod.is_local()),
526 unexpanded_invocations: Default::default(),
527 no_implicit_prelude: false,
528 glob_importers: RefCell::new(Vec::new()),
529 globs: RefCell::new(Vec::new()),
530 traits: RefCell::new(None),
536 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
538 R: AsMut<Resolver<'a>>,
539 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
541 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
542 if let Some(binding) = name_resolution.borrow().binding {
543 f(resolver, key.ident, key.ns, binding);
548 /// This modifies `self` in place. The traits will be stored in `self.traits`.
549 fn ensure_traits<R>(&'a self, resolver: &mut R)
551 R: AsMut<Resolver<'a>>,
553 let mut traits = self.traits.borrow_mut();
554 if traits.is_none() {
555 let mut collected_traits = Vec::new();
556 self.for_each_child(resolver, |_, name, ns, binding| {
560 if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() {
561 collected_traits.push((name, binding))
564 *traits = Some(collected_traits.into_boxed_slice());
568 fn res(&self) -> Option<Res> {
570 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
575 fn def_id(&self) -> Option<DefId> {
577 ModuleKind::Def(_, def_id, _) => Some(def_id),
582 // `self` resolves to the first module ancestor that `is_normal`.
583 fn is_normal(&self) -> bool {
584 matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
587 fn is_trait(&self) -> bool {
588 matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
591 fn nearest_item_scope(&'a self) -> Module<'a> {
593 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
594 self.parent.expect("enum or trait module without a parent")
600 fn is_ancestor_of(&self, mut other: &Self) -> bool {
601 while !ptr::eq(self, other) {
602 if let Some(parent) = other.parent {
612 impl<'a> fmt::Debug for ModuleData<'a> {
613 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
614 write!(f, "{:?}", self.res())
618 /// Records a possibly-private value, type, or module definition.
619 #[derive(Clone, Debug)]
620 pub struct NameBinding<'a> {
621 kind: NameBindingKind<'a>,
622 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
628 pub trait ToNameBinding<'a> {
629 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
632 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
633 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
638 #[derive(Clone, Debug)]
639 enum NameBindingKind<'a> {
640 Res(Res, /* is_macro_export */ bool),
642 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
645 impl<'a> NameBindingKind<'a> {
646 /// Is this a name binding of a import?
647 fn is_import(&self) -> bool {
648 matches!(*self, NameBindingKind::Import { .. })
652 struct PrivacyError<'a> {
654 binding: &'a NameBinding<'a>,
658 struct UseError<'a> {
659 err: DiagnosticBuilder<'a>,
660 /// Candidates which user could `use` to access the missing type.
661 candidates: Vec<ImportSuggestion>,
662 /// The `DefId` of the module to place the use-statements in.
664 /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`).
666 /// Extra free-form suggestion.
667 suggestion: Option<(Span, &'static str, String, Applicability)>,
670 #[derive(Clone, Copy, PartialEq, Debug)]
675 MacroRulesVsModularized,
683 fn descr(self) -> &'static str {
685 AmbiguityKind::Import => "name vs any other name during import resolution",
686 AmbiguityKind::BuiltinAttr => "built-in attribute vs any other name",
687 AmbiguityKind::DeriveHelper => "derive helper attribute vs any other name",
688 AmbiguityKind::MacroRulesVsModularized => {
689 "`macro_rules` vs non-`macro_rules` from other module"
691 AmbiguityKind::GlobVsOuter => {
692 "glob import vs any other name from outer scope during import/macro resolution"
694 AmbiguityKind::GlobVsGlob => "glob import vs glob import in the same module",
695 AmbiguityKind::GlobVsExpanded => {
696 "glob import vs macro-expanded name in the same \
697 module during import/macro resolution"
699 AmbiguityKind::MoreExpandedVsOuter => {
700 "macro-expanded name vs less macro-expanded name \
701 from outer scope during import/macro resolution"
707 /// Miscellaneous bits of metadata for better ambiguity error reporting.
708 #[derive(Clone, Copy, PartialEq)]
709 enum AmbiguityErrorMisc {
716 struct AmbiguityError<'a> {
719 b1: &'a NameBinding<'a>,
720 b2: &'a NameBinding<'a>,
721 misc1: AmbiguityErrorMisc,
722 misc2: AmbiguityErrorMisc,
725 impl<'a> NameBinding<'a> {
726 fn module(&self) -> Option<Module<'a>> {
728 NameBindingKind::Module(module) => Some(module),
729 NameBindingKind::Import { binding, .. } => binding.module(),
734 fn res(&self) -> Res {
736 NameBindingKind::Res(res, _) => res,
737 NameBindingKind::Module(module) => module.res().unwrap(),
738 NameBindingKind::Import { binding, .. } => binding.res(),
742 fn is_ambiguity(&self) -> bool {
743 self.ambiguity.is_some()
745 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
750 fn is_possibly_imported_variant(&self) -> bool {
752 NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
753 _ => self.is_variant(),
757 // We sometimes need to treat variants as `pub` for backwards compatibility.
758 fn pseudo_vis(&self) -> ty::Visibility {
759 if self.is_variant() && self.res().def_id().is_local() {
760 ty::Visibility::Public
766 fn is_variant(&self) -> bool {
769 NameBindingKind::Res(
770 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
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>>,
971 /// Avoid duplicated errors for "name already defined".
972 name_already_seen: FxHashMap<Symbol, Span>,
974 potentially_unused_imports: Vec<&'a Import<'a>>,
976 /// Table for mapping struct IDs into struct constructor IDs,
977 /// it's not used during normal resolution, only for better error reporting.
978 /// Also includes of list of each fields visibility
979 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
981 /// Features enabled for this crate.
982 active_features: FxHashSet<Symbol>,
984 lint_buffer: LintBuffer,
986 next_node_id: NodeId,
988 def_id_to_span: IndexVec<LocalDefId, Span>,
990 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
991 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
993 /// Indices of unnamed struct or variant fields with unresolved attributes.
994 placeholder_field_indices: FxHashMap<NodeId, usize>,
995 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
996 /// we know what parent node that fragment should be attached to thanks to this table.
997 invocation_parents: FxHashMap<ExpnId, LocalDefId>,
999 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1000 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1001 /// FIXME: Replace with a more general AST map (together with some other fields).
1002 trait_impl_items: FxHashSet<LocalDefId>,
1005 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1007 pub struct ResolverArenas<'a> {
1008 modules: TypedArena<ModuleData<'a>>,
1009 local_modules: RefCell<Vec<Module<'a>>>,
1010 imports: TypedArena<Import<'a>>,
1011 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1012 ast_paths: TypedArena<ast::Path>,
1013 dropless: DroplessArena,
1016 impl<'a> ResolverArenas<'a> {
1017 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1018 let module = self.modules.alloc(module);
1019 if module.def_id().map_or(true, |def_id| def_id.is_local()) {
1020 self.local_modules.borrow_mut().push(module);
1024 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1025 self.local_modules.borrow()
1027 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1028 self.dropless.alloc(name_binding)
1030 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1031 self.imports.alloc(import)
1033 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1034 self.name_resolutions.alloc(Default::default())
1036 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1037 PtrKey(self.dropless.alloc(Cell::new(scope)))
1039 fn alloc_macro_rules_binding(
1041 binding: MacroRulesBinding<'a>,
1042 ) -> &'a MacroRulesBinding<'a> {
1043 self.dropless.alloc(binding)
1045 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1046 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1048 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1049 self.dropless.alloc_from_iter(spans)
1053 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1054 fn as_mut(&mut self) -> &mut Resolver<'a> {
1059 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1060 fn parent(self, id: DefId) -> Option<DefId> {
1061 match id.as_local() {
1062 Some(id) => self.definitions.def_key(id).parent,
1063 None => self.cstore().def_key(id).parent,
1065 .map(|index| DefId { index, ..id })
1069 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1070 /// the resolver is no longer needed as all the relevant information is inline.
1071 impl ResolverAstLowering for Resolver<'_> {
1072 fn def_key(&mut self, id: DefId) -> DefKey {
1073 if let Some(id) = id.as_local() {
1074 self.definitions().def_key(id)
1076 self.cstore().def_key(id)
1080 fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
1081 self.cstore().item_generics_num_lifetimes(def_id, sess)
1084 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1085 self.partial_res_map.get(&id).cloned()
1088 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1089 self.import_res_map.get(&id).cloned().unwrap_or_default()
1092 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1093 self.label_res_map.get(&id).cloned()
1096 fn definitions(&mut self) -> &mut Definitions {
1097 &mut self.definitions
1100 fn lint_buffer(&mut self) -> &mut LintBuffer {
1101 &mut self.lint_buffer
1104 fn next_node_id(&mut self) -> NodeId {
1108 fn trait_map(&self) -> &NodeMap<Vec<TraitCandidate>> {
1112 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1113 self.node_id_to_def_id.get(&node).copied()
1116 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1117 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1120 /// Adds a definition with a parent definition.
1124 node_id: ast::NodeId,
1130 !self.node_id_to_def_id.contains_key(&node_id),
1131 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1134 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1137 // Find the next free disambiguator for this key.
1138 let next_disambiguator = &mut self.next_disambiguator;
1139 let next_disambiguator = |parent, data| {
1140 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1141 let disambiguator = *next_disamb;
1142 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1146 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator);
1148 assert_eq!(self.def_id_to_span.push(span), def_id);
1150 // Some things for which we allocate `LocalDefId`s don't correspond to
1151 // anything in the AST, so they don't have a `NodeId`. For these cases
1152 // we don't need a mapping from `NodeId` to `LocalDefId`.
1153 if node_id != ast::DUMMY_NODE_ID {
1154 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1155 self.node_id_to_def_id.insert(node_id, def_id);
1157 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1163 impl<'a> Resolver<'a> {
1165 session: &'a Session,
1168 metadata_loader: &'a MetadataLoaderDyn,
1169 arenas: &'a ResolverArenas<'a>,
1171 let root_local_def_id = LocalDefId { local_def_index: CRATE_DEF_INDEX };
1172 let root_def_id = root_local_def_id.to_def_id();
1173 let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1174 let graph_root = arenas.alloc_module(ModuleData {
1175 no_implicit_prelude: session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1176 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1178 let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1179 let empty_module = arenas.alloc_module(ModuleData {
1180 no_implicit_prelude: true,
1189 let mut module_map = FxHashMap::default();
1190 module_map.insert(root_local_def_id, graph_root);
1192 let definitions = Definitions::new(crate_name, session.local_crate_disambiguator());
1193 let root = definitions.get_root_def();
1195 let mut visibilities = FxHashMap::default();
1196 visibilities.insert(root_local_def_id, ty::Visibility::Public);
1198 let mut def_id_to_span = IndexVec::default();
1199 assert_eq!(def_id_to_span.push(rustc_span::DUMMY_SP), root);
1200 let mut def_id_to_node_id = IndexVec::default();
1201 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1202 let mut node_id_to_def_id = FxHashMap::default();
1203 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1205 let mut invocation_parents = FxHashMap::default();
1206 invocation_parents.insert(ExpnId::root(), root);
1208 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1212 .filter(|(_, entry)| entry.add_prelude)
1213 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1216 if !session.contains_name(&krate.attrs, sym::no_core) {
1217 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1218 if !session.contains_name(&krate.attrs, sym::no_std) {
1219 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1223 let (registered_attrs, registered_tools) =
1224 macros::registered_attrs_and_tools(session, &krate.attrs);
1226 let features = session.features_untracked();
1227 let non_macro_attr =
1228 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1230 let mut resolver = Resolver {
1235 // The outermost module has def ID 0; this is not reflected in the
1241 has_self: FxHashSet::default(),
1242 field_names: FxHashMap::default(),
1244 determined_imports: Vec::new(),
1245 indeterminate_imports: Vec::new(),
1247 last_import_segment: false,
1248 unusable_binding: None,
1250 partial_res_map: Default::default(),
1251 import_res_map: Default::default(),
1252 label_res_map: Default::default(),
1253 extern_crate_map: Default::default(),
1254 export_map: FxHashMap::default(),
1255 trait_map: Default::default(),
1256 underscore_disambiguator: 0,
1259 block_map: Default::default(),
1260 extern_module_map: FxHashMap::default(),
1261 binding_parent_modules: FxHashMap::default(),
1262 ast_transform_scopes: FxHashMap::default(),
1264 glob_map: Default::default(),
1266 used_imports: FxHashSet::default(),
1267 maybe_unused_trait_imports: Default::default(),
1268 maybe_unused_extern_crates: Vec::new(),
1270 privacy_errors: Vec::new(),
1271 ambiguity_errors: Vec::new(),
1272 use_injections: Vec::new(),
1273 macro_expanded_macro_export_errors: BTreeSet::new(),
1276 dummy_binding: arenas.alloc_name_binding(NameBinding {
1277 kind: NameBindingKind::Res(Res::Err, false),
1279 expansion: ExpnId::root(),
1281 vis: ty::Visibility::Public,
1284 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1285 macro_names: FxHashSet::default(),
1286 builtin_macros: Default::default(),
1289 macro_use_prelude: FxHashMap::default(),
1290 all_macros: FxHashMap::default(),
1291 macro_map: FxHashMap::default(),
1292 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1293 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1294 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1295 invocation_parent_scopes: Default::default(),
1296 output_macro_rules_scopes: Default::default(),
1297 helper_attrs: Default::default(),
1298 local_macro_def_scopes: FxHashMap::default(),
1299 name_already_seen: FxHashMap::default(),
1300 potentially_unused_imports: Vec::new(),
1301 struct_constructors: Default::default(),
1302 unused_macros: Default::default(),
1303 proc_macro_stubs: Default::default(),
1304 single_segment_macro_resolutions: Default::default(),
1305 multi_segment_macro_resolutions: Default::default(),
1306 builtin_attrs: Default::default(),
1307 containers_deriving_copy: Default::default(),
1308 active_features: features
1309 .declared_lib_features
1311 .map(|(feat, ..)| *feat)
1312 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1314 lint_buffer: LintBuffer::default(),
1315 next_node_id: NodeId::from_u32(1),
1319 placeholder_field_indices: Default::default(),
1321 next_disambiguator: Default::default(),
1322 trait_impl_items: Default::default(),
1325 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1326 resolver.invocation_parent_scopes.insert(ExpnId::root(), root_parent_scope);
1331 pub fn next_node_id(&mut self) -> NodeId {
1336 .expect("input too large; ran out of NodeIds");
1337 self.next_node_id = ast::NodeId::from_usize(next);
1341 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1342 &mut self.lint_buffer
1345 pub fn arenas() -> ResolverArenas<'a> {
1349 pub fn into_outputs(self) -> ResolverOutputs {
1350 let definitions = self.definitions;
1351 let visibilities = self.visibilities;
1352 let extern_crate_map = self.extern_crate_map;
1353 let export_map = self.export_map;
1354 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1355 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1356 let glob_map = self.glob_map;
1359 cstore: Box::new(self.crate_loader.into_cstore()),
1364 maybe_unused_trait_imports,
1365 maybe_unused_extern_crates,
1366 extern_prelude: self
1369 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1374 pub fn clone_outputs(&self) -> ResolverOutputs {
1376 definitions: self.definitions.clone(),
1377 cstore: Box::new(self.cstore().clone()),
1378 visibilities: self.visibilities.clone(),
1379 extern_crate_map: self.extern_crate_map.clone(),
1380 export_map: self.export_map.clone(),
1381 glob_map: self.glob_map.clone(),
1382 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1383 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1384 extern_prelude: self
1387 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1392 pub fn cstore(&self) -> &CStore {
1393 self.crate_loader.cstore()
1396 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1397 self.non_macro_attrs[mark_used as usize].clone()
1400 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1402 MacroKind::Bang => self.dummy_ext_bang.clone(),
1403 MacroKind::Derive => self.dummy_ext_derive.clone(),
1404 MacroKind::Attr => self.non_macro_attr(true),
1408 /// Runs the function on each namespace.
1409 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1415 fn is_builtin_macro(&mut self, res: Res) -> bool {
1416 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1419 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1421 match ctxt.outer_expn().expn_data().macro_def_id {
1422 Some(def_id) => return def_id,
1423 None => ctxt.remove_mark(),
1428 /// Entry point to crate resolution.
1429 pub fn resolve_crate(&mut self, krate: &Crate) {
1430 self.session.time("resolve_crate", || {
1431 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1432 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1433 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1434 self.session.time("resolve_check_unused", || self.check_unused(krate));
1435 self.session.time("resolve_report_errors", || self.report_errors(krate));
1436 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1440 pub fn traits_in_scope(
1442 current_trait: Option<Module<'a>>,
1443 parent_scope: &ParentScope<'a>,
1444 ctxt: SyntaxContext,
1445 assoc_item: Option<(Symbol, Namespace)>,
1446 ) -> Vec<TraitCandidate> {
1447 let mut found_traits = Vec::new();
1449 if let Some(module) = current_trait {
1450 if self.trait_may_have_item(Some(module), assoc_item) {
1451 let def_id = module.def_id().unwrap();
1452 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1456 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1458 Scope::Module(module) => {
1459 this.traits_in_module(module, assoc_item, &mut found_traits);
1461 Scope::StdLibPrelude => {
1462 if let Some(module) = this.prelude {
1463 this.traits_in_module(module, assoc_item, &mut found_traits);
1466 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1467 _ => unreachable!(),
1475 fn traits_in_module(
1478 assoc_item: Option<(Symbol, Namespace)>,
1479 found_traits: &mut Vec<TraitCandidate>,
1481 module.ensure_traits(self);
1482 let traits = module.traits.borrow();
1483 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1484 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1485 let def_id = trait_binding.res().def_id();
1486 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1487 found_traits.push(TraitCandidate { def_id, import_ids });
1492 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1493 // associated item with the given name and namespace (if specified). This is a conservative
1494 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1495 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1496 // associated items.
1497 fn trait_may_have_item(
1499 trait_module: Option<Module<'a>>,
1500 assoc_item: Option<(Symbol, Namespace)>,
1502 match (trait_module, assoc_item) {
1503 (Some(trait_module), Some((name, ns))) => {
1504 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1505 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1506 assoc_ns == ns && assoc_ident.name == name
1513 fn find_transitive_imports(
1515 mut kind: &NameBindingKind<'_>,
1517 ) -> SmallVec<[LocalDefId; 1]> {
1518 let mut import_ids = smallvec![];
1519 while let NameBindingKind::Import { import, binding, .. } = kind {
1520 let id = self.local_def_id(import.id);
1521 self.maybe_unused_trait_imports.insert(id);
1522 self.add_to_glob_map(&import, trait_name);
1523 import_ids.push(id);
1524 kind = &binding.kind;
1533 nearest_parent_mod: DefId,
1537 let module = ModuleData::new(Some(parent), kind, nearest_parent_mod, expn_id, span);
1538 self.arenas.alloc_module(module)
1541 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1542 let ident = ident.normalize_to_macros_2_0();
1543 let disambiguator = if ident.name == kw::Underscore {
1544 self.underscore_disambiguator += 1;
1545 self.underscore_disambiguator
1549 BindingKey { ident, ns, disambiguator }
1552 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1553 if module.populate_on_access.get() {
1554 module.populate_on_access.set(false);
1555 self.build_reduced_graph_external(module);
1557 &module.lazy_resolutions
1564 ) -> &'a RefCell<NameResolution<'a>> {
1566 .resolutions(module)
1569 .or_insert_with(|| self.arenas.alloc_name_resolution())
1576 used_binding: &'a NameBinding<'a>,
1577 is_lexical_scope: bool,
1579 if let Some((b2, kind)) = used_binding.ambiguity {
1580 self.ambiguity_errors.push(AmbiguityError {
1585 misc1: AmbiguityErrorMisc::None,
1586 misc2: AmbiguityErrorMisc::None,
1589 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1590 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1591 // but not introduce it, as used if they are accessed from lexical scope.
1592 if is_lexical_scope {
1593 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1594 if let Some(crate_item) = entry.extern_crate_item {
1595 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1602 import.used.set(true);
1603 self.used_imports.insert((import.id, ns));
1604 self.add_to_glob_map(&import, ident);
1605 self.record_use(ident, ns, binding, false);
1610 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1611 if import.is_glob() {
1612 let def_id = self.local_def_id(import.id);
1613 self.glob_map.entry(def_id).or_default().insert(ident.name);
1617 /// A generic scope visitor.
1618 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1619 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1622 scope_set: ScopeSet,
1623 parent_scope: &ParentScope<'a>,
1624 ctxt: SyntaxContext,
1625 mut visitor: impl FnMut(
1628 /*use_prelude*/ bool,
1632 // General principles:
1633 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1634 // built into the language or standard library. This way we can add new names into the
1635 // language or standard library without breaking user code.
1636 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1637 // Places to search (in order of decreasing priority):
1639 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1640 // (open set, not controlled).
1641 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1642 // (open, not controlled).
1643 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1644 // 4. Tool modules (closed, controlled right now, but not in the future).
1645 // 5. Standard library prelude (de-facto closed, controlled).
1646 // 6. Language prelude (closed, controlled).
1648 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1649 // (open set, not controlled).
1650 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1651 // (open, not controlled).
1652 // 3. Standard library prelude (de-facto closed, controlled).
1654 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1655 // are currently reported as errors. They should be higher in priority than preludes
1656 // and probably even names in modules according to the "general principles" above. They
1657 // also should be subject to restricted shadowing because are effectively produced by
1658 // derives (you need to resolve the derive first to add helpers into scope), but they
1659 // should be available before the derive is expanded for compatibility.
1660 // It's mess in general, so we are being conservative for now.
1661 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1662 // priority than prelude macros, but create ambiguities with macros in modules.
1663 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1664 // (open, not controlled). Have higher priority than prelude macros, but create
1665 // ambiguities with `macro_rules`.
1666 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1667 // 4a. User-defined prelude from macro-use
1668 // (open, the open part is from macro expansions, not controlled).
1669 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1670 // 4c. Standard library prelude (de-facto closed, controlled).
1671 // 6. Language prelude: builtin attributes (closed, controlled).
1673 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1674 let (ns, macro_kind, is_absolute_path) = match scope_set {
1675 ScopeSet::All(ns, _) => (ns, None, false),
1676 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1677 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1679 // Jump out of trait or enum modules, they do not act as scopes.
1680 let module = parent_scope.module.nearest_item_scope();
1681 let mut scope = match ns {
1682 _ if is_absolute_path => Scope::CrateRoot,
1683 TypeNS | ValueNS => Scope::Module(module),
1684 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1686 let mut ctxt = ctxt.normalize_to_macros_2_0();
1687 let mut use_prelude = !module.no_implicit_prelude;
1690 let visit = match scope {
1691 // Derive helpers are not in scope when resolving derives in the same container.
1692 Scope::DeriveHelpers(expn_id) => {
1693 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1695 Scope::DeriveHelpersCompat => true,
1696 Scope::MacroRules(macro_rules_scope) => {
1697 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1698 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1699 // As another consequence of this optimization visitors never observe invocation
1700 // scopes for macros that were already expanded.
1701 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1702 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1703 macro_rules_scope.set(next_scope.get());
1710 Scope::CrateRoot => true,
1711 Scope::Module(..) => true,
1712 Scope::RegisteredAttrs => use_prelude,
1713 Scope::MacroUsePrelude => use_prelude || rust_2015,
1714 Scope::BuiltinAttrs => true,
1715 Scope::ExternPrelude => use_prelude || is_absolute_path,
1716 Scope::ToolPrelude => use_prelude,
1717 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1718 Scope::BuiltinTypes => true,
1722 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1723 return break_result;
1727 scope = match scope {
1728 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1729 // Derive helpers are not visible to code generated by bang or derive macros.
1730 let expn_data = expn_id.expn_data();
1731 match expn_data.kind {
1733 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1734 Scope::DeriveHelpersCompat
1736 _ => Scope::DeriveHelpers(expn_data.parent),
1739 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1740 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1741 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1742 MacroRulesScope::Binding(binding) => {
1743 Scope::MacroRules(binding.parent_macro_rules_scope)
1745 MacroRulesScope::Invocation(invoc_id) => {
1746 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1748 MacroRulesScope::Empty => Scope::Module(module),
1750 Scope::CrateRoot => match ns {
1752 ctxt.adjust(ExpnId::root());
1753 Scope::ExternPrelude
1755 ValueNS | MacroNS => break,
1757 Scope::Module(module) => {
1758 use_prelude = !module.no_implicit_prelude;
1759 match self.hygienic_lexical_parent(module, &mut ctxt) {
1760 Some(parent_module) => Scope::Module(parent_module),
1762 ctxt.adjust(ExpnId::root());
1764 TypeNS => Scope::ExternPrelude,
1765 ValueNS => Scope::StdLibPrelude,
1766 MacroNS => Scope::RegisteredAttrs,
1771 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1772 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1773 Scope::BuiltinAttrs => break, // nowhere else to search
1774 Scope::ExternPrelude if is_absolute_path => break,
1775 Scope::ExternPrelude => Scope::ToolPrelude,
1776 Scope::ToolPrelude => Scope::StdLibPrelude,
1777 Scope::StdLibPrelude => match ns {
1778 TypeNS => Scope::BuiltinTypes,
1779 ValueNS => break, // nowhere else to search
1780 MacroNS => Scope::BuiltinAttrs,
1782 Scope::BuiltinTypes => break, // nowhere else to search
1789 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1790 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1791 /// `ident` in the first scope that defines it (or None if no scopes define it).
1793 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1794 /// the items are defined in the block. For example,
1797 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1800 /// g(); // This resolves to the local variable `g` since it shadows the item.
1804 /// Invariant: This must only be called during main resolution, not during
1805 /// import resolution.
1806 fn resolve_ident_in_lexical_scope(
1810 parent_scope: &ParentScope<'a>,
1811 record_used_id: Option<NodeId>,
1814 ) -> Option<LexicalScopeBinding<'a>> {
1815 assert!(ns == TypeNS || ns == ValueNS);
1816 if ident.name == kw::Empty {
1817 return Some(LexicalScopeBinding::Res(Res::Err));
1819 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1820 // FIXME(jseyfried) improve `Self` hygiene
1821 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1822 (empty_span, empty_span)
1823 } else if ns == TypeNS {
1824 let normalized_span = ident.span.normalize_to_macros_2_0();
1825 (normalized_span, normalized_span)
1827 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1829 ident.span = general_span;
1830 let normalized_ident = Ident { span: normalized_span, ..ident };
1832 // Walk backwards up the ribs in scope.
1833 let record_used = record_used_id.is_some();
1834 let mut module = self.graph_root;
1835 for i in (0..ribs.len()).rev() {
1836 debug!("walk rib\n{:?}", ribs[i].bindings);
1837 // Use the rib kind to determine whether we are resolving parameters
1838 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1839 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1840 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1842 // The ident resolves to a type parameter or local variable.
1843 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1849 *original_rib_ident_def,
1854 module = match ribs[i].kind {
1855 ModuleRibKind(module) => module,
1856 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1857 // If an invocation of this macro created `ident`, give up on `ident`
1858 // and switch to `ident`'s source from the macro definition.
1859 ident.span.remove_mark();
1865 let item = self.resolve_ident_in_module_unadjusted(
1866 ModuleOrUniformRoot::Module(module),
1873 if let Ok(binding) = item {
1874 // The ident resolves to an item.
1875 return Some(LexicalScopeBinding::Item(binding));
1879 ModuleKind::Block(..) => {} // We can see through blocks
1884 ident = normalized_ident;
1885 let mut poisoned = None;
1887 let mut span_data = ident.span.data();
1888 let opt_module = if let Some(node_id) = record_used_id {
1889 self.hygienic_lexical_parent_with_compatibility_fallback(
1891 &mut span_data.ctxt,
1896 self.hygienic_lexical_parent(module, &mut span_data.ctxt)
1898 ident.span = span_data.span();
1899 module = unwrap_or!(opt_module, break);
1900 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1901 let result = self.resolve_ident_in_module_unadjusted(
1902 ModuleOrUniformRoot::Module(module),
1905 adjusted_parent_scope,
1912 if let Some(node_id) = poisoned {
1913 self.lint_buffer.buffer_lint_with_diagnostic(
1914 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1917 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1918 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(ident.span),
1921 return Some(LexicalScopeBinding::Item(binding));
1923 Err(Determined) => continue,
1924 Err(Undetermined) => {
1925 span_bug!(ident.span, "undetermined resolution during main resolution pass")
1930 if !module.no_implicit_prelude {
1931 ident.span.adjust(ExpnId::root());
1933 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1934 return Some(LexicalScopeBinding::Item(binding));
1936 if let Some(ident) = self.registered_tools.get(&ident) {
1938 (Res::ToolMod, ty::Visibility::Public, ident.span, ExpnId::root())
1939 .to_name_binding(self.arenas);
1940 return Some(LexicalScopeBinding::Item(binding));
1943 if let Some(prelude) = self.prelude {
1944 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1945 ModuleOrUniformRoot::Module(prelude),
1952 return Some(LexicalScopeBinding::Item(binding));
1958 if let Some(prim_ty) = PrimTy::from_name(ident.name) {
1960 (Res::PrimTy(prim_ty), ty::Visibility::Public, DUMMY_SP, ExpnId::root())
1961 .to_name_binding(self.arenas);
1962 return Some(LexicalScopeBinding::Item(binding));
1969 fn hygienic_lexical_parent(
1972 ctxt: &mut SyntaxContext,
1973 ) -> Option<Module<'a>> {
1974 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
1975 return Some(self.macro_def_scope(ctxt.remove_mark()));
1978 if let ModuleKind::Block(..) = module.kind {
1979 return Some(module.parent.unwrap().nearest_item_scope());
1985 fn hygienic_lexical_parent_with_compatibility_fallback(
1988 ctxt: &mut SyntaxContext,
1990 poisoned: &mut Option<NodeId>,
1991 ) -> Option<Module<'a>> {
1992 if let module @ Some(..) = self.hygienic_lexical_parent(module, ctxt) {
1996 // We need to support the next case under a deprecation warning
1999 // ---- begin: this comes from a proc macro derive
2000 // mod implementation_details {
2001 // // Note that `MyStruct` is not in scope here.
2002 // impl SomeTrait for MyStruct { ... }
2006 // So we have to fall back to the module's parent during lexical resolution in this case.
2007 if let Some(parent) = module.parent {
2008 // Inner module is inside the macro, parent module is outside of the macro.
2009 if module.expansion != parent.expansion
2010 && module.expansion.is_descendant_of(parent.expansion)
2012 // The macro is a proc macro derive
2013 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
2014 let ext = self.get_macro_by_def_id(def_id);
2015 if ext.builtin_name.is_none()
2016 && ext.macro_kind() == MacroKind::Derive
2017 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
2019 *poisoned = Some(node_id);
2020 return module.parent;
2029 fn resolve_ident_in_module(
2031 module: ModuleOrUniformRoot<'a>,
2034 parent_scope: &ParentScope<'a>,
2037 ) -> Result<&'a NameBinding<'a>, Determinacy> {
2038 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
2039 .map_err(|(determinacy, _)| determinacy)
2042 fn resolve_ident_in_module_ext(
2044 module: ModuleOrUniformRoot<'a>,
2047 parent_scope: &ParentScope<'a>,
2050 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2051 let tmp_parent_scope;
2052 let mut adjusted_parent_scope = parent_scope;
2054 ModuleOrUniformRoot::Module(m) => {
2055 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2057 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
2058 adjusted_parent_scope = &tmp_parent_scope;
2061 ModuleOrUniformRoot::ExternPrelude => {
2062 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2064 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2068 self.resolve_ident_in_module_unadjusted_ext(
2072 adjusted_parent_scope,
2079 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2080 debug!("resolve_crate_root({:?})", ident);
2081 let mut ctxt = ident.span.ctxt();
2082 let mark = if ident.name == kw::DollarCrate {
2083 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2084 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2085 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2086 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2087 // definitions actually produced by `macro` and `macro` definitions produced by
2088 // `macro_rules!`, but at least such configurations are not stable yet.
2089 ctxt = ctxt.normalize_to_macro_rules();
2091 "resolve_crate_root: marks={:?}",
2092 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2094 let mut iter = ctxt.marks().into_iter().rev().peekable();
2095 let mut result = None;
2096 // Find the last opaque mark from the end if it exists.
2097 while let Some(&(mark, transparency)) = iter.peek() {
2098 if transparency == Transparency::Opaque {
2099 result = Some(mark);
2106 "resolve_crate_root: found opaque mark {:?} {:?}",
2108 result.map(|r| r.expn_data())
2110 // Then find the last semi-transparent mark from the end if it exists.
2111 for (mark, transparency) in iter {
2112 if transparency == Transparency::SemiTransparent {
2113 result = Some(mark);
2119 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2121 result.map(|r| r.expn_data())
2125 debug!("resolve_crate_root: not DollarCrate");
2126 ctxt = ctxt.normalize_to_macros_2_0();
2127 ctxt.adjust(ExpnId::root())
2129 let module = match mark {
2130 Some(def) => self.macro_def_scope(def),
2133 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2136 return self.graph_root;
2139 let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.nearest_parent_mod });
2141 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2150 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2151 let mut module = self.get_module(module.nearest_parent_mod);
2152 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2153 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
2154 module = self.get_module(parent.nearest_parent_mod);
2162 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2163 parent_scope: &ParentScope<'a>,
2166 crate_lint: CrateLint,
2167 ) -> PathResult<'a> {
2168 self.resolve_path_with_ribs(
2179 fn resolve_path_with_ribs(
2182 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2183 parent_scope: &ParentScope<'a>,
2186 crate_lint: CrateLint,
2187 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2188 ) -> PathResult<'a> {
2189 let mut module = None;
2190 let mut allow_super = true;
2191 let mut second_binding = None;
2194 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2195 path_span={:?}, crate_lint={:?})",
2196 path, opt_ns, record_used, path_span, crate_lint,
2199 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2200 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2201 let record_segment_res = |this: &mut Self, res| {
2203 if let Some(id) = id {
2204 if !this.partial_res_map.contains_key(&id) {
2205 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2206 this.record_partial_res(id, PartialRes::new(res));
2212 let is_last = i == path.len() - 1;
2213 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2214 let name = ident.name;
2216 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2219 if allow_super && name == kw::Super {
2220 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2221 let self_module = match i {
2222 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2224 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2228 if let Some(self_module) = self_module {
2229 if let Some(parent) = self_module.parent {
2230 module = Some(ModuleOrUniformRoot::Module(
2231 self.resolve_self(&mut ctxt, parent),
2236 let msg = "there are too many leading `super` keywords".to_string();
2237 return PathResult::Failed {
2241 is_error_from_last_segment: false,
2245 if name == kw::SelfLower {
2246 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2247 module = Some(ModuleOrUniformRoot::Module(
2248 self.resolve_self(&mut ctxt, parent_scope.module),
2252 if name == kw::PathRoot && ident.span.rust_2018() {
2253 module = Some(ModuleOrUniformRoot::ExternPrelude);
2256 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2257 // `::a::b` from 2015 macro on 2018 global edition
2258 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2261 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2262 // `::a::b`, `crate::a::b` or `$crate::a::b`
2263 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2269 // Report special messages for path segment keywords in wrong positions.
2270 if ident.is_path_segment_keyword() && i != 0 {
2271 let name_str = if name == kw::PathRoot {
2272 "crate root".to_string()
2274 format!("`{}`", name)
2276 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2277 format!("global paths cannot start with {}", name_str)
2279 format!("{} in paths can only be used in start position", name_str)
2281 return PathResult::Failed {
2285 is_error_from_last_segment: false,
2289 enum FindBindingResult<'a> {
2290 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2291 PathResult(PathResult<'a>),
2293 let find_binding_in_ns = |this: &mut Self, ns| {
2294 let binding = if let Some(module) = module {
2295 this.resolve_ident_in_module(
2303 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2304 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2305 this.early_resolve_ident_in_lexical_scope(
2314 let record_used_id = if record_used {
2315 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2319 match this.resolve_ident_in_lexical_scope(
2327 // we found a locally-imported or available item/module
2328 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2329 // we found a local variable or type param
2330 Some(LexicalScopeBinding::Res(res))
2331 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2333 record_segment_res(this, res);
2334 return FindBindingResult::PathResult(PathResult::NonModule(
2335 PartialRes::with_unresolved_segments(res, path.len() - 1),
2338 _ => Err(Determinacy::determined(record_used)),
2341 FindBindingResult::Binding(binding)
2343 let binding = match find_binding_in_ns(self, ns) {
2344 FindBindingResult::PathResult(x) => return x,
2345 FindBindingResult::Binding(binding) => binding,
2350 second_binding = Some(binding);
2352 let res = binding.res();
2353 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2354 if let Some(next_module) = binding.module() {
2355 module = Some(ModuleOrUniformRoot::Module(next_module));
2356 record_segment_res(self, res);
2357 } else if res == Res::ToolMod && i + 1 != path.len() {
2358 if binding.is_import() {
2362 "cannot use a tool module through an import",
2364 .span_note(binding.span, "the tool module imported here")
2367 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2368 return PathResult::NonModule(PartialRes::new(res));
2369 } else if res == Res::Err {
2370 return PathResult::NonModule(PartialRes::new(Res::Err));
2371 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2372 self.lint_if_path_starts_with_module(
2378 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2383 let label = format!(
2384 "`{}` is {} {}, not a module",
2390 return PathResult::Failed {
2394 is_error_from_last_segment: is_last,
2398 Err(Undetermined) => return PathResult::Indeterminate,
2399 Err(Determined) => {
2400 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2401 if opt_ns.is_some() && !module.is_normal() {
2402 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2403 module.res().unwrap(),
2408 let module_res = match module {
2409 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2412 let (label, suggestion) = if module_res == self.graph_root.res() {
2413 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2414 // Don't look up import candidates if this is a speculative resolve
2415 let mut candidates = if record_used {
2416 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2420 candidates.sort_by_cached_key(|c| {
2421 (c.path.segments.len(), pprust::path_to_string(&c.path))
2423 if let Some(candidate) = candidates.get(0) {
2425 String::from("unresolved import"),
2427 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2428 String::from("a similar path exists"),
2429 Applicability::MaybeIncorrect,
2433 (format!("maybe a missing crate `{}`?", ident), None)
2441 .map_or(false, |c| c.is_ascii_uppercase())
2443 (format!("use of undeclared type `{}`", ident), None)
2445 (format!("use of undeclared crate or module `{}`", ident), None)
2448 let parent = path[i - 1].ident.name;
2449 let parent = if parent == kw::PathRoot {
2450 "crate root".to_owned()
2452 format!("`{}`", parent)
2455 let mut msg = format!("could not find `{}` in {}", ident, parent);
2456 if ns == TypeNS || ns == ValueNS {
2457 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2458 if let FindBindingResult::Binding(Ok(binding)) =
2459 find_binding_in_ns(self, ns_to_try)
2461 let mut found = |what| {
2463 "expected {}, found {} `{}` in {}",
2470 if binding.module().is_some() {
2473 match binding.res() {
2474 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2475 _ => found(ns_to_try.descr()),
2482 return PathResult::Failed {
2486 is_error_from_last_segment: is_last,
2492 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2494 PathResult::Module(match module {
2495 Some(module) => module,
2496 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2497 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2501 fn lint_if_path_starts_with_module(
2503 crate_lint: CrateLint,
2506 second_binding: Option<&NameBinding<'_>>,
2508 let (diag_id, diag_span) = match crate_lint {
2509 CrateLint::No => return,
2510 CrateLint::SimplePath(id) => (id, path_span),
2511 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2512 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2515 let first_name = match path.get(0) {
2516 // In the 2018 edition this lint is a hard error, so nothing to do
2517 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2521 // We're only interested in `use` paths which should start with
2522 // `{{root}}` currently.
2523 if first_name != kw::PathRoot {
2528 // If this import looks like `crate::...` it's already good
2529 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2530 // Otherwise go below to see if it's an extern crate
2532 // If the path has length one (and it's `PathRoot` most likely)
2533 // then we don't know whether we're gonna be importing a crate or an
2534 // item in our crate. Defer this lint to elsewhere
2538 // If the first element of our path was actually resolved to an
2539 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2540 // warning, this looks all good!
2541 if let Some(binding) = second_binding {
2542 if let NameBindingKind::Import { import, .. } = binding.kind {
2543 // Careful: we still want to rewrite paths from renamed extern crates.
2544 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2550 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2551 self.lint_buffer.buffer_lint_with_diagnostic(
2552 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2555 "absolute paths must start with `self`, `super`, \
2556 `crate`, or an external crate name in the 2018 edition",
2561 // Validate a local resolution (from ribs).
2562 fn validate_res_from_ribs(
2569 original_rib_ident_def: Ident,
2570 all_ribs: &[Rib<'a>],
2572 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2573 debug!("validate_res_from_ribs({:?})", res);
2574 let ribs = &all_ribs[rib_index + 1..];
2576 // An invalid forward use of a type parameter from a previous default.
2577 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2579 let res_error = if rib_ident.name == kw::SelfUpper {
2580 ResolutionError::SelfInTyParamDefault
2582 ResolutionError::ForwardDeclaredTyParam
2584 self.report_error(span, res_error);
2586 assert_eq!(res, Res::Err);
2592 use ResolutionError::*;
2593 let mut res_err = None;
2598 | ClosureOrAsyncRibKind
2600 | MacroDefinition(..)
2601 | ForwardTyParamBanRibKind => {
2602 // Nothing to do. Continue.
2604 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2605 // This was an attempt to access an upvar inside a
2606 // named function item. This is not allowed, so we
2609 // We don't immediately trigger a resolve error, because
2610 // we want certain other resolution errors (namely those
2611 // emitted for `ConstantItemRibKind` below) to take
2613 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2616 ConstantItemRibKind(_, item) => {
2617 // Still doesn't deal with upvars
2619 let (span, resolution_error) =
2620 if let Some((ident, constant_item_kind)) = item {
2621 let kind_str = match constant_item_kind {
2622 ConstantItemKind::Const => "const",
2623 ConstantItemKind::Static => "static",
2627 AttemptToUseNonConstantValueInConstant(
2628 ident, "let", kind_str,
2634 AttemptToUseNonConstantValueInConstant(
2635 original_rib_ident_def,
2641 self.report_error(span, resolution_error);
2645 ConstParamTyRibKind => {
2647 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2653 if let Some(res_err) = res_err {
2654 self.report_error(span, res_err);
2658 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2659 let mut in_ty_param_default = false;
2661 let has_generic_params = match rib.kind {
2663 | ClosureOrAsyncRibKind
2666 | MacroDefinition(..) => {
2667 // Nothing to do. Continue.
2671 // We only forbid constant items if we are inside of type defaults,
2672 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2673 ForwardTyParamBanRibKind => {
2674 in_ty_param_default = true;
2677 ConstantItemRibKind(trivial, _) => {
2678 let features = self.session.features_untracked();
2679 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2681 || features.const_generics
2682 || features.lazy_normalization_consts)
2684 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2685 // we can't easily tell if it's generic at this stage, so we instead remember
2686 // this and then enforce the self type to be concrete later on.
2687 if let Res::SelfTy(trait_def, Some((impl_def, _))) = res {
2688 res = Res::SelfTy(trait_def, Some((impl_def, true)));
2693 ResolutionError::ParamInNonTrivialAnonConst {
2694 name: rib_ident.name,
2700 self.session.delay_span_bug(span, CG_BUG_STR);
2705 if in_ty_param_default {
2709 ResolutionError::ParamInAnonConstInTyDefault(
2720 // This was an attempt to use a type parameter outside its scope.
2721 ItemRibKind(has_generic_params) => has_generic_params,
2722 FnItemRibKind => HasGenericParams::Yes,
2723 ConstParamTyRibKind => {
2727 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2737 ResolutionError::GenericParamsFromOuterFunction(
2746 Res::Def(DefKind::ConstParam, _) => {
2747 let mut ribs = ribs.iter().peekable();
2748 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2749 // When declaring const parameters inside function signatures, the first rib
2750 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2751 // (spuriously) conflicting with the const param.
2755 let mut in_ty_param_default = false;
2757 let has_generic_params = match rib.kind {
2759 | ClosureOrAsyncRibKind
2762 | MacroDefinition(..) => continue,
2764 // We only forbid constant items if we are inside of type defaults,
2765 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2766 ForwardTyParamBanRibKind => {
2767 in_ty_param_default = true;
2770 ConstantItemRibKind(trivial, _) => {
2771 let features = self.session.features_untracked();
2772 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2774 || features.const_generics
2775 || features.lazy_normalization_consts)
2780 ResolutionError::ParamInNonTrivialAnonConst {
2781 name: rib_ident.name,
2787 self.session.delay_span_bug(span, CG_BUG_STR);
2791 if in_ty_param_default {
2795 ResolutionError::ParamInAnonConstInTyDefault(
2806 ItemRibKind(has_generic_params) => has_generic_params,
2807 FnItemRibKind => HasGenericParams::Yes,
2808 ConstParamTyRibKind => {
2812 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2819 // This was an attempt to use a const parameter outside its scope.
2823 ResolutionError::GenericParamsFromOuterFunction(
2837 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2838 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2839 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2840 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2844 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2845 vis.is_accessible_from(module.nearest_parent_mod, self)
2848 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2849 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2850 if !ptr::eq(module, old_module) {
2851 span_bug!(binding.span, "parent module is reset for binding");
2856 fn disambiguate_macro_rules_vs_modularized(
2858 macro_rules: &'a NameBinding<'a>,
2859 modularized: &'a NameBinding<'a>,
2861 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2862 // is disambiguated to mitigate regressions from macro modularization.
2863 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2865 self.binding_parent_modules.get(&PtrKey(macro_rules)),
2866 self.binding_parent_modules.get(&PtrKey(modularized)),
2868 (Some(macro_rules), Some(modularized)) => {
2869 macro_rules.nearest_parent_mod == modularized.nearest_parent_mod
2870 && modularized.is_ancestor_of(macro_rules)
2876 fn report_errors(&mut self, krate: &Crate) {
2877 self.report_with_use_injections(krate);
2879 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2880 let msg = "macro-expanded `macro_export` macros from the current crate \
2881 cannot be referred to by absolute paths";
2882 self.lint_buffer.buffer_lint_with_diagnostic(
2883 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2887 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2891 for ambiguity_error in &self.ambiguity_errors {
2892 self.report_ambiguity_error(ambiguity_error);
2895 let mut reported_spans = FxHashSet::default();
2896 for error in &self.privacy_errors {
2897 if reported_spans.insert(error.dedup_span) {
2898 self.report_privacy_error(error);
2903 fn report_with_use_injections(&mut self, krate: &Crate) {
2904 for UseError { mut err, candidates, def_id, instead, suggestion } in
2905 self.use_injections.drain(..)
2907 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
2908 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
2912 if !candidates.is_empty() {
2913 diagnostics::show_candidates(&mut err, span, &candidates, instead, found_use);
2914 } else if let Some((span, msg, sugg, appl)) = suggestion {
2915 err.span_suggestion(span, msg, sugg, appl);
2921 fn report_conflict<'b>(
2926 new_binding: &NameBinding<'b>,
2927 old_binding: &NameBinding<'b>,
2929 // Error on the second of two conflicting names
2930 if old_binding.span.lo() > new_binding.span.lo() {
2931 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2934 let container = match parent.kind {
2935 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id().unwrap()),
2936 ModuleKind::Block(..) => "block",
2939 let old_noun = match old_binding.is_import() {
2941 false => "definition",
2944 let new_participle = match new_binding.is_import() {
2950 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
2952 if let Some(s) = self.name_already_seen.get(&name) {
2958 let old_kind = match (ns, old_binding.module()) {
2959 (ValueNS, _) => "value",
2960 (MacroNS, _) => "macro",
2961 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2962 (TypeNS, Some(module)) if module.is_normal() => "module",
2963 (TypeNS, Some(module)) if module.is_trait() => "trait",
2964 (TypeNS, _) => "type",
2967 let msg = format!("the name `{}` is defined multiple times", name);
2969 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2970 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2971 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2972 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2973 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2975 _ => match (old_binding.is_import(), new_binding.is_import()) {
2976 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2977 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2978 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2983 "`{}` must be defined only once in the {} namespace of this {}",
2989 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2991 self.session.source_map().guess_head_span(old_binding.span),
2992 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2995 // See https://github.com/rust-lang/rust/issues/32354
2996 use NameBindingKind::Import;
2997 let import = match (&new_binding.kind, &old_binding.kind) {
2998 // If there are two imports where one or both have attributes then prefer removing the
2999 // import without attributes.
3000 (Import { import: new, .. }, Import { import: old, .. })
3002 !new_binding.span.is_dummy()
3003 && !old_binding.span.is_dummy()
3004 && (new.has_attributes || old.has_attributes)
3007 if old.has_attributes {
3008 Some((new, new_binding.span, true))
3010 Some((old, old_binding.span, true))
3013 // Otherwise prioritize the new binding.
3014 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
3015 Some((import, new_binding.span, other.is_import()))
3017 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
3018 Some((import, old_binding.span, other.is_import()))
3023 // Check if the target of the use for both bindings is the same.
3024 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
3025 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
3027 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
3028 // Only suggest removing an import if both bindings are to the same def, if both spans
3029 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
3030 // been introduced by a item.
3031 let should_remove_import = duplicate
3033 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
3036 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3037 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3039 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3040 // Simple case - remove the entire import. Due to the above match arm, this can
3041 // only be a single use so just remove it entirely.
3042 err.tool_only_span_suggestion(
3043 import.use_span_with_attributes,
3044 "remove unnecessary import",
3046 Applicability::MaybeIncorrect,
3049 Some((import, span, _)) => {
3050 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3056 self.name_already_seen.insert(name, span);
3059 /// This function adds a suggestion to change the binding name of a new import that conflicts
3060 /// with an existing import.
3062 /// ```text,ignore (diagnostic)
3063 /// help: you can use `as` to change the binding name of the import
3065 /// LL | use foo::bar as other_bar;
3066 /// | ^^^^^^^^^^^^^^^^^^^^^
3068 fn add_suggestion_for_rename_of_use(
3070 err: &mut DiagnosticBuilder<'_>,
3072 import: &Import<'_>,
3075 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3076 format!("Other{}", name)
3078 format!("other_{}", name)
3081 let mut suggestion = None;
3083 ImportKind::Single { type_ns_only: true, .. } => {
3084 suggestion = Some(format!("self as {}", suggested_name))
3086 ImportKind::Single { source, .. } => {
3088 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3090 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3091 if pos <= snippet.len() {
3092 suggestion = Some(format!(
3096 if snippet.ends_with(';') { ";" } else { "" }
3102 ImportKind::ExternCrate { source, target, .. } => {
3103 suggestion = Some(format!(
3104 "extern crate {} as {};",
3105 source.unwrap_or(target.name),
3109 _ => unreachable!(),
3112 let rename_msg = "you can use `as` to change the binding name of the import";
3113 if let Some(suggestion) = suggestion {
3114 err.span_suggestion(
3118 Applicability::MaybeIncorrect,
3121 err.span_label(binding_span, rename_msg);
3125 /// This function adds a suggestion to remove a unnecessary binding from an import that is
3126 /// nested. In the following example, this function will be invoked to remove the `a` binding
3127 /// in the second use statement:
3129 /// ```ignore (diagnostic)
3130 /// use issue_52891::a;
3131 /// use issue_52891::{d, a, e};
3134 /// The following suggestion will be added:
3136 /// ```ignore (diagnostic)
3137 /// use issue_52891::{d, a, e};
3138 /// ^-- help: remove unnecessary import
3141 /// If the nested use contains only one import then the suggestion will remove the entire
3144 /// It is expected that the provided import is nested - this isn't checked by the
3145 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3146 /// as characters expected by span manipulations won't be present.
3147 fn add_suggestion_for_duplicate_nested_use(
3149 err: &mut DiagnosticBuilder<'_>,
3150 import: &Import<'_>,
3153 assert!(import.is_nested());
3154 let message = "remove unnecessary import";
3156 // Two examples will be used to illustrate the span manipulations we're doing:
3158 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3159 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3160 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3161 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3163 let (found_closing_brace, span) =
3164 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3166 // If there was a closing brace then identify the span to remove any trailing commas from
3167 // previous imports.
3168 if found_closing_brace {
3169 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3170 err.tool_only_span_suggestion(
3174 Applicability::MaybeIncorrect,
3177 // Remove the entire line if we cannot extend the span back, this indicates a
3178 // `issue_52891::{self}` case.
3179 err.span_suggestion(
3180 import.use_span_with_attributes,
3183 Applicability::MaybeIncorrect,
3190 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3193 fn extern_prelude_get(
3197 ) -> Option<&'a NameBinding<'a>> {
3198 if ident.is_path_segment_keyword() {
3199 // Make sure `self`, `super` etc produce an error when passed to here.
3202 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3203 if let Some(binding) = entry.extern_crate_item {
3204 if !speculative && entry.introduced_by_item {
3205 self.record_use(ident, TypeNS, binding, false);
3209 let crate_id = if !speculative {
3210 self.crate_loader.process_path_extern(ident.name, ident.span)
3212 self.crate_loader.maybe_process_path_extern(ident.name)?
3214 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
3216 (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
3217 .to_name_binding(self.arenas),
3223 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3224 /// isn't something that can be returned because it can't be made to live that long,
3225 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3226 /// just that an error occurred.
3227 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3228 pub fn resolve_str_path_error(
3234 ) -> Result<(ast::Path, Res), ()> {
3235 let path = if path_str.starts_with("::") {
3238 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3239 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3240 .map(|i| self.new_ast_path_segment(i))
3249 .map(Ident::from_str)
3250 .map(|i| self.new_ast_path_segment(i))
3255 let module = self.get_module(module_id);
3256 let parent_scope = &ParentScope::module(module, self);
3257 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3261 // Resolve a path passed from rustdoc or HIR lowering.
3262 fn resolve_ast_path(
3266 parent_scope: &ParentScope<'a>,
3267 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3268 match self.resolve_path(
3269 &Segment::from_path(path),
3276 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3277 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3278 Ok(path_res.base_res())
3280 PathResult::NonModule(..) => Err((
3282 ResolutionError::FailedToResolve {
3283 label: String::from("type-relative paths are not supported in this context"),
3287 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3288 PathResult::Failed { span, label, suggestion, .. } => {
3289 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3294 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3295 let mut seg = ast::PathSegment::from_ident(ident);
3296 seg.id = self.next_node_id();
3301 pub fn graph_root(&self) -> Module<'a> {
3306 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3310 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3312 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3313 if let Some(def_id) = def_id.as_local() { Some(self.def_id_to_span[def_id]) } else { None }
3317 fn names_to_string(names: &[Symbol]) -> String {
3318 let mut result = String::new();
3319 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3321 result.push_str("::");
3323 if Ident::with_dummy_span(*name).is_raw_guess() {
3324 result.push_str("r#");
3326 result.push_str(&name.as_str());
3331 fn path_names_to_string(path: &Path) -> String {
3332 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3335 /// A somewhat inefficient routine to obtain the name of a module.
3336 fn module_to_string(module: Module<'_>) -> Option<String> {
3337 let mut names = Vec::new();
3339 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3340 if let ModuleKind::Def(.., name) = module.kind {
3341 if let Some(parent) = module.parent {
3343 collect_mod(names, parent);
3346 names.push(Symbol::intern("<opaque>"));
3347 collect_mod(names, module.parent.unwrap());
3350 collect_mod(&mut names, module);
3352 if names.is_empty() {
3356 Some(names_to_string(&names))
3359 #[derive(Copy, Clone, Debug)]
3361 /// Do not issue the lint.
3364 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3365 /// In this case, we can take the span of that path.
3368 /// This lint comes from a `use` statement. In this case, what we
3369 /// care about really is the *root* `use` statement; e.g., if we
3370 /// have nested things like `use a::{b, c}`, we care about the
3372 UsePath { root_id: NodeId, root_span: Span },
3374 /// This is the "trait item" from a fully qualified path. For example,
3375 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3376 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3377 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3381 fn node_id(&self) -> Option<NodeId> {
3383 CrateLint::No => None,
3384 CrateLint::SimplePath(id)
3385 | CrateLint::UsePath { root_id: id, .. }
3386 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3391 pub fn provide(providers: &mut Providers) {
3392 late::lifetimes::provide(providers);