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>>,
970 /// Resolutions for paths inside the `#[derive(...)]` attribute with the given `ExpnId`.
971 derive_resolutions: FxHashMap<ExpnId, Vec<(Lrc<SyntaxExtension>, ast::Path)>>,
973 /// Avoid duplicated errors for "name already defined".
974 name_already_seen: FxHashMap<Symbol, Span>,
976 potentially_unused_imports: Vec<&'a Import<'a>>,
978 /// Table for mapping struct IDs into struct constructor IDs,
979 /// it's not used during normal resolution, only for better error reporting.
980 /// Also includes of list of each fields visibility
981 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
983 /// Features enabled for this crate.
984 active_features: FxHashSet<Symbol>,
986 lint_buffer: LintBuffer,
988 next_node_id: NodeId,
990 def_id_to_span: IndexVec<LocalDefId, Span>,
992 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
993 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
995 /// Indices of unnamed struct or variant fields with unresolved attributes.
996 placeholder_field_indices: FxHashMap<NodeId, usize>,
997 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
998 /// we know what parent node that fragment should be attached to thanks to this table.
999 invocation_parents: FxHashMap<ExpnId, LocalDefId>,
1001 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1002 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1003 /// FIXME: Replace with a more general AST map (together with some other fields).
1004 trait_impl_items: FxHashSet<LocalDefId>,
1007 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1009 pub struct ResolverArenas<'a> {
1010 modules: TypedArena<ModuleData<'a>>,
1011 local_modules: RefCell<Vec<Module<'a>>>,
1012 imports: TypedArena<Import<'a>>,
1013 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1014 ast_paths: TypedArena<ast::Path>,
1015 dropless: DroplessArena,
1018 impl<'a> ResolverArenas<'a> {
1019 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1020 let module = self.modules.alloc(module);
1021 if module.def_id().map_or(true, |def_id| def_id.is_local()) {
1022 self.local_modules.borrow_mut().push(module);
1026 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1027 self.local_modules.borrow()
1029 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1030 self.dropless.alloc(name_binding)
1032 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1033 self.imports.alloc(import)
1035 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1036 self.name_resolutions.alloc(Default::default())
1038 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1039 PtrKey(self.dropless.alloc(Cell::new(scope)))
1041 fn alloc_macro_rules_binding(
1043 binding: MacroRulesBinding<'a>,
1044 ) -> &'a MacroRulesBinding<'a> {
1045 self.dropless.alloc(binding)
1047 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1048 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1050 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1051 self.dropless.alloc_from_iter(spans)
1055 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1056 fn as_mut(&mut self) -> &mut Resolver<'a> {
1061 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1062 fn parent(self, id: DefId) -> Option<DefId> {
1063 match id.as_local() {
1064 Some(id) => self.definitions.def_key(id).parent,
1065 None => self.cstore().def_key(id).parent,
1067 .map(|index| DefId { index, ..id })
1071 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1072 /// the resolver is no longer needed as all the relevant information is inline.
1073 impl ResolverAstLowering for Resolver<'_> {
1074 fn def_key(&mut self, id: DefId) -> DefKey {
1075 if let Some(id) = id.as_local() {
1076 self.definitions().def_key(id)
1078 self.cstore().def_key(id)
1082 fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
1083 self.cstore().item_generics_num_lifetimes(def_id, sess)
1086 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1087 self.partial_res_map.get(&id).cloned()
1090 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1091 self.import_res_map.get(&id).cloned().unwrap_or_default()
1094 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1095 self.label_res_map.get(&id).cloned()
1098 fn definitions(&mut self) -> &mut Definitions {
1099 &mut self.definitions
1102 fn lint_buffer(&mut self) -> &mut LintBuffer {
1103 &mut self.lint_buffer
1106 fn next_node_id(&mut self) -> NodeId {
1110 fn trait_map(&self) -> &NodeMap<Vec<TraitCandidate>> {
1114 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1115 self.node_id_to_def_id.get(&node).copied()
1118 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1119 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1122 /// Adds a definition with a parent definition.
1126 node_id: ast::NodeId,
1132 !self.node_id_to_def_id.contains_key(&node_id),
1133 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1136 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1139 // Find the next free disambiguator for this key.
1140 let next_disambiguator = &mut self.next_disambiguator;
1141 let next_disambiguator = |parent, data| {
1142 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1143 let disambiguator = *next_disamb;
1144 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1148 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator);
1150 assert_eq!(self.def_id_to_span.push(span), def_id);
1152 // Some things for which we allocate `LocalDefId`s don't correspond to
1153 // anything in the AST, so they don't have a `NodeId`. For these cases
1154 // we don't need a mapping from `NodeId` to `LocalDefId`.
1155 if node_id != ast::DUMMY_NODE_ID {
1156 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1157 self.node_id_to_def_id.insert(node_id, def_id);
1159 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1165 impl<'a> Resolver<'a> {
1167 session: &'a Session,
1170 metadata_loader: &'a MetadataLoaderDyn,
1171 arenas: &'a ResolverArenas<'a>,
1173 let root_local_def_id = LocalDefId { local_def_index: CRATE_DEF_INDEX };
1174 let root_def_id = root_local_def_id.to_def_id();
1175 let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1176 let graph_root = arenas.alloc_module(ModuleData {
1177 no_implicit_prelude: session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1178 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1180 let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1181 let empty_module = arenas.alloc_module(ModuleData {
1182 no_implicit_prelude: true,
1191 let mut module_map = FxHashMap::default();
1192 module_map.insert(root_local_def_id, graph_root);
1194 let definitions = Definitions::new(crate_name, session.local_crate_disambiguator());
1195 let root = definitions.get_root_def();
1197 let mut visibilities = FxHashMap::default();
1198 visibilities.insert(root_local_def_id, ty::Visibility::Public);
1200 let mut def_id_to_span = IndexVec::default();
1201 assert_eq!(def_id_to_span.push(rustc_span::DUMMY_SP), root);
1202 let mut def_id_to_node_id = IndexVec::default();
1203 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1204 let mut node_id_to_def_id = FxHashMap::default();
1205 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1207 let mut invocation_parents = FxHashMap::default();
1208 invocation_parents.insert(ExpnId::root(), root);
1210 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1214 .filter(|(_, entry)| entry.add_prelude)
1215 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1218 if !session.contains_name(&krate.attrs, sym::no_core) {
1219 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1220 if !session.contains_name(&krate.attrs, sym::no_std) {
1221 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1225 let (registered_attrs, registered_tools) =
1226 macros::registered_attrs_and_tools(session, &krate.attrs);
1228 let features = session.features_untracked();
1229 let non_macro_attr =
1230 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1232 let mut resolver = Resolver {
1237 // The outermost module has def ID 0; this is not reflected in the
1243 has_self: FxHashSet::default(),
1244 field_names: FxHashMap::default(),
1246 determined_imports: Vec::new(),
1247 indeterminate_imports: Vec::new(),
1249 last_import_segment: false,
1250 unusable_binding: None,
1252 partial_res_map: Default::default(),
1253 import_res_map: Default::default(),
1254 label_res_map: Default::default(),
1255 extern_crate_map: Default::default(),
1256 export_map: FxHashMap::default(),
1257 trait_map: Default::default(),
1258 underscore_disambiguator: 0,
1261 block_map: Default::default(),
1262 extern_module_map: FxHashMap::default(),
1263 binding_parent_modules: FxHashMap::default(),
1264 ast_transform_scopes: FxHashMap::default(),
1266 glob_map: Default::default(),
1268 used_imports: FxHashSet::default(),
1269 maybe_unused_trait_imports: Default::default(),
1270 maybe_unused_extern_crates: Vec::new(),
1272 privacy_errors: Vec::new(),
1273 ambiguity_errors: Vec::new(),
1274 use_injections: Vec::new(),
1275 macro_expanded_macro_export_errors: BTreeSet::new(),
1278 dummy_binding: arenas.alloc_name_binding(NameBinding {
1279 kind: NameBindingKind::Res(Res::Err, false),
1281 expansion: ExpnId::root(),
1283 vis: ty::Visibility::Public,
1286 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1287 macro_names: FxHashSet::default(),
1288 builtin_macros: Default::default(),
1291 macro_use_prelude: FxHashMap::default(),
1292 all_macros: FxHashMap::default(),
1293 macro_map: FxHashMap::default(),
1294 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1295 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1296 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1297 invocation_parent_scopes: Default::default(),
1298 output_macro_rules_scopes: Default::default(),
1299 helper_attrs: Default::default(),
1300 derive_resolutions: Default::default(),
1301 local_macro_def_scopes: FxHashMap::default(),
1302 name_already_seen: FxHashMap::default(),
1303 potentially_unused_imports: Vec::new(),
1304 struct_constructors: Default::default(),
1305 unused_macros: Default::default(),
1306 proc_macro_stubs: Default::default(),
1307 single_segment_macro_resolutions: Default::default(),
1308 multi_segment_macro_resolutions: Default::default(),
1309 builtin_attrs: Default::default(),
1310 containers_deriving_copy: Default::default(),
1311 active_features: features
1312 .declared_lib_features
1314 .map(|(feat, ..)| *feat)
1315 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1317 lint_buffer: LintBuffer::default(),
1318 next_node_id: NodeId::from_u32(1),
1322 placeholder_field_indices: Default::default(),
1324 next_disambiguator: Default::default(),
1325 trait_impl_items: Default::default(),
1328 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1329 resolver.invocation_parent_scopes.insert(ExpnId::root(), root_parent_scope);
1334 pub fn next_node_id(&mut self) -> NodeId {
1339 .expect("input too large; ran out of NodeIds");
1340 self.next_node_id = ast::NodeId::from_usize(next);
1344 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1345 &mut self.lint_buffer
1348 pub fn arenas() -> ResolverArenas<'a> {
1352 pub fn into_outputs(self) -> ResolverOutputs {
1353 let definitions = self.definitions;
1354 let visibilities = self.visibilities;
1355 let extern_crate_map = self.extern_crate_map;
1356 let export_map = self.export_map;
1357 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1358 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1359 let glob_map = self.glob_map;
1362 cstore: Box::new(self.crate_loader.into_cstore()),
1367 maybe_unused_trait_imports,
1368 maybe_unused_extern_crates,
1369 extern_prelude: self
1372 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1377 pub fn clone_outputs(&self) -> ResolverOutputs {
1379 definitions: self.definitions.clone(),
1380 cstore: Box::new(self.cstore().clone()),
1381 visibilities: self.visibilities.clone(),
1382 extern_crate_map: self.extern_crate_map.clone(),
1383 export_map: self.export_map.clone(),
1384 glob_map: self.glob_map.clone(),
1385 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1386 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1387 extern_prelude: self
1390 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1395 pub fn cstore(&self) -> &CStore {
1396 self.crate_loader.cstore()
1399 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1400 self.non_macro_attrs[mark_used as usize].clone()
1403 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1405 MacroKind::Bang => self.dummy_ext_bang.clone(),
1406 MacroKind::Derive => self.dummy_ext_derive.clone(),
1407 MacroKind::Attr => self.non_macro_attr(true),
1411 /// Runs the function on each namespace.
1412 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1418 fn is_builtin_macro(&mut self, res: Res) -> bool {
1419 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1422 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1424 match ctxt.outer_expn().expn_data().macro_def_id {
1425 Some(def_id) => return def_id,
1426 None => ctxt.remove_mark(),
1431 /// Entry point to crate resolution.
1432 pub fn resolve_crate(&mut self, krate: &Crate) {
1433 self.session.time("resolve_crate", || {
1434 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1435 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1436 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1437 self.session.time("resolve_check_unused", || self.check_unused(krate));
1438 self.session.time("resolve_report_errors", || self.report_errors(krate));
1439 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1443 pub fn traits_in_scope(
1445 current_trait: Option<Module<'a>>,
1446 parent_scope: &ParentScope<'a>,
1447 ctxt: SyntaxContext,
1448 assoc_item: Option<(Symbol, Namespace)>,
1449 ) -> Vec<TraitCandidate> {
1450 let mut found_traits = Vec::new();
1452 if let Some(module) = current_trait {
1453 if self.trait_may_have_item(Some(module), assoc_item) {
1454 let def_id = module.def_id().unwrap();
1455 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1459 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1461 Scope::Module(module) => {
1462 this.traits_in_module(module, assoc_item, &mut found_traits);
1464 Scope::StdLibPrelude => {
1465 if let Some(module) = this.prelude {
1466 this.traits_in_module(module, assoc_item, &mut found_traits);
1469 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1470 _ => unreachable!(),
1478 fn traits_in_module(
1481 assoc_item: Option<(Symbol, Namespace)>,
1482 found_traits: &mut Vec<TraitCandidate>,
1484 module.ensure_traits(self);
1485 let traits = module.traits.borrow();
1486 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1487 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1488 let def_id = trait_binding.res().def_id();
1489 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1490 found_traits.push(TraitCandidate { def_id, import_ids });
1495 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1496 // associated item with the given name and namespace (if specified). This is a conservative
1497 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1498 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1499 // associated items.
1500 fn trait_may_have_item(
1502 trait_module: Option<Module<'a>>,
1503 assoc_item: Option<(Symbol, Namespace)>,
1505 match (trait_module, assoc_item) {
1506 (Some(trait_module), Some((name, ns))) => {
1507 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1508 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1509 assoc_ns == ns && assoc_ident.name == name
1516 fn find_transitive_imports(
1518 mut kind: &NameBindingKind<'_>,
1520 ) -> SmallVec<[LocalDefId; 1]> {
1521 let mut import_ids = smallvec![];
1522 while let NameBindingKind::Import { import, binding, .. } = kind {
1523 let id = self.local_def_id(import.id);
1524 self.maybe_unused_trait_imports.insert(id);
1525 self.add_to_glob_map(&import, trait_name);
1526 import_ids.push(id);
1527 kind = &binding.kind;
1536 nearest_parent_mod: DefId,
1540 let module = ModuleData::new(Some(parent), kind, nearest_parent_mod, expn_id, span);
1541 self.arenas.alloc_module(module)
1544 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1545 let ident = ident.normalize_to_macros_2_0();
1546 let disambiguator = if ident.name == kw::Underscore {
1547 self.underscore_disambiguator += 1;
1548 self.underscore_disambiguator
1552 BindingKey { ident, ns, disambiguator }
1555 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1556 if module.populate_on_access.get() {
1557 module.populate_on_access.set(false);
1558 self.build_reduced_graph_external(module);
1560 &module.lazy_resolutions
1567 ) -> &'a RefCell<NameResolution<'a>> {
1569 .resolutions(module)
1572 .or_insert_with(|| self.arenas.alloc_name_resolution())
1579 used_binding: &'a NameBinding<'a>,
1580 is_lexical_scope: bool,
1582 if let Some((b2, kind)) = used_binding.ambiguity {
1583 self.ambiguity_errors.push(AmbiguityError {
1588 misc1: AmbiguityErrorMisc::None,
1589 misc2: AmbiguityErrorMisc::None,
1592 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1593 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1594 // but not introduce it, as used if they are accessed from lexical scope.
1595 if is_lexical_scope {
1596 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1597 if let Some(crate_item) = entry.extern_crate_item {
1598 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1605 import.used.set(true);
1606 self.used_imports.insert((import.id, ns));
1607 self.add_to_glob_map(&import, ident);
1608 self.record_use(ident, ns, binding, false);
1613 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1614 if import.is_glob() {
1615 let def_id = self.local_def_id(import.id);
1616 self.glob_map.entry(def_id).or_default().insert(ident.name);
1620 /// A generic scope visitor.
1621 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1622 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1625 scope_set: ScopeSet,
1626 parent_scope: &ParentScope<'a>,
1627 ctxt: SyntaxContext,
1628 mut visitor: impl FnMut(
1631 /*use_prelude*/ bool,
1635 // General principles:
1636 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1637 // built into the language or standard library. This way we can add new names into the
1638 // language or standard library without breaking user code.
1639 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1640 // Places to search (in order of decreasing priority):
1642 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1643 // (open set, not controlled).
1644 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1645 // (open, not controlled).
1646 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1647 // 4. Tool modules (closed, controlled right now, but not in the future).
1648 // 5. Standard library prelude (de-facto closed, controlled).
1649 // 6. Language prelude (closed, controlled).
1651 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1652 // (open set, not controlled).
1653 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1654 // (open, not controlled).
1655 // 3. Standard library prelude (de-facto closed, controlled).
1657 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1658 // are currently reported as errors. They should be higher in priority than preludes
1659 // and probably even names in modules according to the "general principles" above. They
1660 // also should be subject to restricted shadowing because are effectively produced by
1661 // derives (you need to resolve the derive first to add helpers into scope), but they
1662 // should be available before the derive is expanded for compatibility.
1663 // It's mess in general, so we are being conservative for now.
1664 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1665 // priority than prelude macros, but create ambiguities with macros in modules.
1666 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1667 // (open, not controlled). Have higher priority than prelude macros, but create
1668 // ambiguities with `macro_rules`.
1669 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1670 // 4a. User-defined prelude from macro-use
1671 // (open, the open part is from macro expansions, not controlled).
1672 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1673 // 4c. Standard library prelude (de-facto closed, controlled).
1674 // 6. Language prelude: builtin attributes (closed, controlled).
1676 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1677 let (ns, macro_kind, is_absolute_path) = match scope_set {
1678 ScopeSet::All(ns, _) => (ns, None, false),
1679 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1680 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1682 // Jump out of trait or enum modules, they do not act as scopes.
1683 let module = parent_scope.module.nearest_item_scope();
1684 let mut scope = match ns {
1685 _ if is_absolute_path => Scope::CrateRoot,
1686 TypeNS | ValueNS => Scope::Module(module),
1687 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1689 let mut ctxt = ctxt.normalize_to_macros_2_0();
1690 let mut use_prelude = !module.no_implicit_prelude;
1693 let visit = match scope {
1694 // Derive helpers are not in scope when resolving derives in the same container.
1695 Scope::DeriveHelpers(expn_id) => {
1696 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1698 Scope::DeriveHelpersCompat => true,
1699 Scope::MacroRules(macro_rules_scope) => {
1700 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1701 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1702 // As another consequence of this optimization visitors never observe invocation
1703 // scopes for macros that were already expanded.
1704 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1705 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1706 macro_rules_scope.set(next_scope.get());
1713 Scope::CrateRoot => true,
1714 Scope::Module(..) => true,
1715 Scope::RegisteredAttrs => use_prelude,
1716 Scope::MacroUsePrelude => use_prelude || rust_2015,
1717 Scope::BuiltinAttrs => true,
1718 Scope::ExternPrelude => use_prelude || is_absolute_path,
1719 Scope::ToolPrelude => use_prelude,
1720 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1721 Scope::BuiltinTypes => true,
1725 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1726 return break_result;
1730 scope = match scope {
1731 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1732 // Derive helpers are not visible to code generated by bang or derive macros.
1733 let expn_data = expn_id.expn_data();
1734 match expn_data.kind {
1736 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1737 Scope::DeriveHelpersCompat
1739 _ => Scope::DeriveHelpers(expn_data.parent),
1742 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1743 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1744 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1745 MacroRulesScope::Binding(binding) => {
1746 Scope::MacroRules(binding.parent_macro_rules_scope)
1748 MacroRulesScope::Invocation(invoc_id) => {
1749 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1751 MacroRulesScope::Empty => Scope::Module(module),
1753 Scope::CrateRoot => match ns {
1755 ctxt.adjust(ExpnId::root());
1756 Scope::ExternPrelude
1758 ValueNS | MacroNS => break,
1760 Scope::Module(module) => {
1761 use_prelude = !module.no_implicit_prelude;
1762 match self.hygienic_lexical_parent(module, &mut ctxt) {
1763 Some(parent_module) => Scope::Module(parent_module),
1765 ctxt.adjust(ExpnId::root());
1767 TypeNS => Scope::ExternPrelude,
1768 ValueNS => Scope::StdLibPrelude,
1769 MacroNS => Scope::RegisteredAttrs,
1774 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1775 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1776 Scope::BuiltinAttrs => break, // nowhere else to search
1777 Scope::ExternPrelude if is_absolute_path => break,
1778 Scope::ExternPrelude => Scope::ToolPrelude,
1779 Scope::ToolPrelude => Scope::StdLibPrelude,
1780 Scope::StdLibPrelude => match ns {
1781 TypeNS => Scope::BuiltinTypes,
1782 ValueNS => break, // nowhere else to search
1783 MacroNS => Scope::BuiltinAttrs,
1785 Scope::BuiltinTypes => break, // nowhere else to search
1792 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1793 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1794 /// `ident` in the first scope that defines it (or None if no scopes define it).
1796 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1797 /// the items are defined in the block. For example,
1800 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1803 /// g(); // This resolves to the local variable `g` since it shadows the item.
1807 /// Invariant: This must only be called during main resolution, not during
1808 /// import resolution.
1809 fn resolve_ident_in_lexical_scope(
1813 parent_scope: &ParentScope<'a>,
1814 record_used_id: Option<NodeId>,
1817 ) -> Option<LexicalScopeBinding<'a>> {
1818 assert!(ns == TypeNS || ns == ValueNS);
1819 if ident.name == kw::Empty {
1820 return Some(LexicalScopeBinding::Res(Res::Err));
1822 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1823 // FIXME(jseyfried) improve `Self` hygiene
1824 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1825 (empty_span, empty_span)
1826 } else if ns == TypeNS {
1827 let normalized_span = ident.span.normalize_to_macros_2_0();
1828 (normalized_span, normalized_span)
1830 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1832 ident.span = general_span;
1833 let normalized_ident = Ident { span: normalized_span, ..ident };
1835 // Walk backwards up the ribs in scope.
1836 let record_used = record_used_id.is_some();
1837 let mut module = self.graph_root;
1838 for i in (0..ribs.len()).rev() {
1839 debug!("walk rib\n{:?}", ribs[i].bindings);
1840 // Use the rib kind to determine whether we are resolving parameters
1841 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1842 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1843 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1845 // The ident resolves to a type parameter or local variable.
1846 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1852 *original_rib_ident_def,
1857 module = match ribs[i].kind {
1858 ModuleRibKind(module) => module,
1859 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1860 // If an invocation of this macro created `ident`, give up on `ident`
1861 // and switch to `ident`'s source from the macro definition.
1862 ident.span.remove_mark();
1868 let item = self.resolve_ident_in_module_unadjusted(
1869 ModuleOrUniformRoot::Module(module),
1876 if let Ok(binding) = item {
1877 // The ident resolves to an item.
1878 return Some(LexicalScopeBinding::Item(binding));
1882 ModuleKind::Block(..) => {} // We can see through blocks
1887 ident = normalized_ident;
1888 let mut poisoned = None;
1890 let mut span_data = ident.span.data();
1891 let opt_module = if let Some(node_id) = record_used_id {
1892 self.hygienic_lexical_parent_with_compatibility_fallback(
1894 &mut span_data.ctxt,
1899 self.hygienic_lexical_parent(module, &mut span_data.ctxt)
1901 ident.span = span_data.span();
1902 module = unwrap_or!(opt_module, break);
1903 let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
1904 let result = self.resolve_ident_in_module_unadjusted(
1905 ModuleOrUniformRoot::Module(module),
1908 adjusted_parent_scope,
1915 if let Some(node_id) = poisoned {
1916 self.lint_buffer.buffer_lint_with_diagnostic(
1917 lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK,
1920 &format!("cannot find {} `{}` in this scope", ns.descr(), ident),
1921 BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(ident.span),
1924 return Some(LexicalScopeBinding::Item(binding));
1926 Err(Determined) => continue,
1927 Err(Undetermined) => {
1928 span_bug!(ident.span, "undetermined resolution during main resolution pass")
1933 if !module.no_implicit_prelude {
1934 ident.span.adjust(ExpnId::root());
1936 if let Some(binding) = self.extern_prelude_get(ident, !record_used) {
1937 return Some(LexicalScopeBinding::Item(binding));
1939 if let Some(ident) = self.registered_tools.get(&ident) {
1941 (Res::ToolMod, ty::Visibility::Public, ident.span, ExpnId::root())
1942 .to_name_binding(self.arenas);
1943 return Some(LexicalScopeBinding::Item(binding));
1946 if let Some(prelude) = self.prelude {
1947 if let Ok(binding) = self.resolve_ident_in_module_unadjusted(
1948 ModuleOrUniformRoot::Module(prelude),
1955 return Some(LexicalScopeBinding::Item(binding));
1961 if let Some(prim_ty) = PrimTy::from_name(ident.name) {
1963 (Res::PrimTy(prim_ty), ty::Visibility::Public, DUMMY_SP, ExpnId::root())
1964 .to_name_binding(self.arenas);
1965 return Some(LexicalScopeBinding::Item(binding));
1972 fn hygienic_lexical_parent(
1975 ctxt: &mut SyntaxContext,
1976 ) -> Option<Module<'a>> {
1977 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
1978 return Some(self.macro_def_scope(ctxt.remove_mark()));
1981 if let ModuleKind::Block(..) = module.kind {
1982 return Some(module.parent.unwrap().nearest_item_scope());
1988 fn hygienic_lexical_parent_with_compatibility_fallback(
1991 ctxt: &mut SyntaxContext,
1993 poisoned: &mut Option<NodeId>,
1994 ) -> Option<Module<'a>> {
1995 if let module @ Some(..) = self.hygienic_lexical_parent(module, ctxt) {
1999 // We need to support the next case under a deprecation warning
2002 // ---- begin: this comes from a proc macro derive
2003 // mod implementation_details {
2004 // // Note that `MyStruct` is not in scope here.
2005 // impl SomeTrait for MyStruct { ... }
2009 // So we have to fall back to the module's parent during lexical resolution in this case.
2010 if let Some(parent) = module.parent {
2011 // Inner module is inside the macro, parent module is outside of the macro.
2012 if module.expansion != parent.expansion
2013 && module.expansion.is_descendant_of(parent.expansion)
2015 // The macro is a proc macro derive
2016 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
2017 let ext = self.get_macro_by_def_id(def_id);
2018 if ext.builtin_name.is_none()
2019 && ext.macro_kind() == MacroKind::Derive
2020 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
2022 *poisoned = Some(node_id);
2023 return module.parent;
2032 fn resolve_ident_in_module(
2034 module: ModuleOrUniformRoot<'a>,
2037 parent_scope: &ParentScope<'a>,
2040 ) -> Result<&'a NameBinding<'a>, Determinacy> {
2041 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
2042 .map_err(|(determinacy, _)| determinacy)
2045 fn resolve_ident_in_module_ext(
2047 module: ModuleOrUniformRoot<'a>,
2050 parent_scope: &ParentScope<'a>,
2053 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2054 let tmp_parent_scope;
2055 let mut adjusted_parent_scope = parent_scope;
2057 ModuleOrUniformRoot::Module(m) => {
2058 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2060 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
2061 adjusted_parent_scope = &tmp_parent_scope;
2064 ModuleOrUniformRoot::ExternPrelude => {
2065 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2067 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2071 self.resolve_ident_in_module_unadjusted_ext(
2075 adjusted_parent_scope,
2082 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2083 debug!("resolve_crate_root({:?})", ident);
2084 let mut ctxt = ident.span.ctxt();
2085 let mark = if ident.name == kw::DollarCrate {
2086 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2087 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2088 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2089 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2090 // definitions actually produced by `macro` and `macro` definitions produced by
2091 // `macro_rules!`, but at least such configurations are not stable yet.
2092 ctxt = ctxt.normalize_to_macro_rules();
2094 "resolve_crate_root: marks={:?}",
2095 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2097 let mut iter = ctxt.marks().into_iter().rev().peekable();
2098 let mut result = None;
2099 // Find the last opaque mark from the end if it exists.
2100 while let Some(&(mark, transparency)) = iter.peek() {
2101 if transparency == Transparency::Opaque {
2102 result = Some(mark);
2109 "resolve_crate_root: found opaque mark {:?} {:?}",
2111 result.map(|r| r.expn_data())
2113 // Then find the last semi-transparent mark from the end if it exists.
2114 for (mark, transparency) in iter {
2115 if transparency == Transparency::SemiTransparent {
2116 result = Some(mark);
2122 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2124 result.map(|r| r.expn_data())
2128 debug!("resolve_crate_root: not DollarCrate");
2129 ctxt = ctxt.normalize_to_macros_2_0();
2130 ctxt.adjust(ExpnId::root())
2132 let module = match mark {
2133 Some(def) => self.macro_def_scope(def),
2136 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2139 return self.graph_root;
2142 let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.nearest_parent_mod });
2144 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2153 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2154 let mut module = self.get_module(module.nearest_parent_mod);
2155 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2156 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
2157 module = self.get_module(parent.nearest_parent_mod);
2165 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2166 parent_scope: &ParentScope<'a>,
2169 crate_lint: CrateLint,
2170 ) -> PathResult<'a> {
2171 self.resolve_path_with_ribs(
2182 fn resolve_path_with_ribs(
2185 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2186 parent_scope: &ParentScope<'a>,
2189 crate_lint: CrateLint,
2190 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2191 ) -> PathResult<'a> {
2192 let mut module = None;
2193 let mut allow_super = true;
2194 let mut second_binding = None;
2197 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2198 path_span={:?}, crate_lint={:?})",
2199 path, opt_ns, record_used, path_span, crate_lint,
2202 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2203 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2204 let record_segment_res = |this: &mut Self, res| {
2206 if let Some(id) = id {
2207 if !this.partial_res_map.contains_key(&id) {
2208 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2209 this.record_partial_res(id, PartialRes::new(res));
2215 let is_last = i == path.len() - 1;
2216 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2217 let name = ident.name;
2219 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2222 if allow_super && name == kw::Super {
2223 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2224 let self_module = match i {
2225 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2227 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2231 if let Some(self_module) = self_module {
2232 if let Some(parent) = self_module.parent {
2233 module = Some(ModuleOrUniformRoot::Module(
2234 self.resolve_self(&mut ctxt, parent),
2239 let msg = "there are too many leading `super` keywords".to_string();
2240 return PathResult::Failed {
2244 is_error_from_last_segment: false,
2248 if name == kw::SelfLower {
2249 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2250 module = Some(ModuleOrUniformRoot::Module(
2251 self.resolve_self(&mut ctxt, parent_scope.module),
2255 if name == kw::PathRoot && ident.span.rust_2018() {
2256 module = Some(ModuleOrUniformRoot::ExternPrelude);
2259 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2260 // `::a::b` from 2015 macro on 2018 global edition
2261 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2264 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2265 // `::a::b`, `crate::a::b` or `$crate::a::b`
2266 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2272 // Report special messages for path segment keywords in wrong positions.
2273 if ident.is_path_segment_keyword() && i != 0 {
2274 let name_str = if name == kw::PathRoot {
2275 "crate root".to_string()
2277 format!("`{}`", name)
2279 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2280 format!("global paths cannot start with {}", name_str)
2282 format!("{} in paths can only be used in start position", name_str)
2284 return PathResult::Failed {
2288 is_error_from_last_segment: false,
2292 enum FindBindingResult<'a> {
2293 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2294 PathResult(PathResult<'a>),
2296 let find_binding_in_ns = |this: &mut Self, ns| {
2297 let binding = if let Some(module) = module {
2298 this.resolve_ident_in_module(
2306 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2307 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2308 this.early_resolve_ident_in_lexical_scope(
2317 let record_used_id = if record_used {
2318 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2322 match this.resolve_ident_in_lexical_scope(
2330 // we found a locally-imported or available item/module
2331 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2332 // we found a local variable or type param
2333 Some(LexicalScopeBinding::Res(res))
2334 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2336 record_segment_res(this, res);
2337 return FindBindingResult::PathResult(PathResult::NonModule(
2338 PartialRes::with_unresolved_segments(res, path.len() - 1),
2341 _ => Err(Determinacy::determined(record_used)),
2344 FindBindingResult::Binding(binding)
2346 let binding = match find_binding_in_ns(self, ns) {
2347 FindBindingResult::PathResult(x) => return x,
2348 FindBindingResult::Binding(binding) => binding,
2353 second_binding = Some(binding);
2355 let res = binding.res();
2356 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2357 if let Some(next_module) = binding.module() {
2358 module = Some(ModuleOrUniformRoot::Module(next_module));
2359 record_segment_res(self, res);
2360 } else if res == Res::ToolMod && i + 1 != path.len() {
2361 if binding.is_import() {
2365 "cannot use a tool module through an import",
2367 .span_note(binding.span, "the tool module imported here")
2370 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2371 return PathResult::NonModule(PartialRes::new(res));
2372 } else if res == Res::Err {
2373 return PathResult::NonModule(PartialRes::new(Res::Err));
2374 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2375 self.lint_if_path_starts_with_module(
2381 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2386 let label = format!(
2387 "`{}` is {} {}, not a module",
2393 return PathResult::Failed {
2397 is_error_from_last_segment: is_last,
2401 Err(Undetermined) => return PathResult::Indeterminate,
2402 Err(Determined) => {
2403 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2404 if opt_ns.is_some() && !module.is_normal() {
2405 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2406 module.res().unwrap(),
2411 let module_res = match module {
2412 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2415 let (label, suggestion) = if module_res == self.graph_root.res() {
2416 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2417 // Don't look up import candidates if this is a speculative resolve
2418 let mut candidates = if record_used {
2419 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2423 candidates.sort_by_cached_key(|c| {
2424 (c.path.segments.len(), pprust::path_to_string(&c.path))
2426 if let Some(candidate) = candidates.get(0) {
2428 String::from("unresolved import"),
2430 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2431 String::from("a similar path exists"),
2432 Applicability::MaybeIncorrect,
2436 (format!("maybe a missing crate `{}`?", ident), None)
2444 .map_or(false, |c| c.is_ascii_uppercase())
2446 (format!("use of undeclared type `{}`", ident), None)
2448 (format!("use of undeclared crate or module `{}`", ident), None)
2451 let parent = path[i - 1].ident.name;
2452 let parent = if parent == kw::PathRoot {
2453 "crate root".to_owned()
2455 format!("`{}`", parent)
2458 let mut msg = format!("could not find `{}` in {}", ident, parent);
2459 if ns == TypeNS || ns == ValueNS {
2460 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2461 if let FindBindingResult::Binding(Ok(binding)) =
2462 find_binding_in_ns(self, ns_to_try)
2464 let mut found = |what| {
2466 "expected {}, found {} `{}` in {}",
2473 if binding.module().is_some() {
2476 match binding.res() {
2477 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2478 _ => found(ns_to_try.descr()),
2485 return PathResult::Failed {
2489 is_error_from_last_segment: is_last,
2495 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2497 PathResult::Module(match module {
2498 Some(module) => module,
2499 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2500 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2504 fn lint_if_path_starts_with_module(
2506 crate_lint: CrateLint,
2509 second_binding: Option<&NameBinding<'_>>,
2511 let (diag_id, diag_span) = match crate_lint {
2512 CrateLint::No => return,
2513 CrateLint::SimplePath(id) => (id, path_span),
2514 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2515 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2518 let first_name = match path.get(0) {
2519 // In the 2018 edition this lint is a hard error, so nothing to do
2520 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2524 // We're only interested in `use` paths which should start with
2525 // `{{root}}` currently.
2526 if first_name != kw::PathRoot {
2531 // If this import looks like `crate::...` it's already good
2532 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2533 // Otherwise go below to see if it's an extern crate
2535 // If the path has length one (and it's `PathRoot` most likely)
2536 // then we don't know whether we're gonna be importing a crate or an
2537 // item in our crate. Defer this lint to elsewhere
2541 // If the first element of our path was actually resolved to an
2542 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2543 // warning, this looks all good!
2544 if let Some(binding) = second_binding {
2545 if let NameBindingKind::Import { import, .. } = binding.kind {
2546 // Careful: we still want to rewrite paths from renamed extern crates.
2547 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2553 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2554 self.lint_buffer.buffer_lint_with_diagnostic(
2555 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2558 "absolute paths must start with `self`, `super`, \
2559 `crate`, or an external crate name in the 2018 edition",
2564 // Validate a local resolution (from ribs).
2565 fn validate_res_from_ribs(
2572 original_rib_ident_def: Ident,
2573 all_ribs: &[Rib<'a>],
2575 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2576 debug!("validate_res_from_ribs({:?})", res);
2577 let ribs = &all_ribs[rib_index + 1..];
2579 // An invalid forward use of a type parameter from a previous default.
2580 if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind {
2582 let res_error = if rib_ident.name == kw::SelfUpper {
2583 ResolutionError::SelfInTyParamDefault
2585 ResolutionError::ForwardDeclaredTyParam
2587 self.report_error(span, res_error);
2589 assert_eq!(res, Res::Err);
2595 use ResolutionError::*;
2596 let mut res_err = None;
2601 | ClosureOrAsyncRibKind
2603 | MacroDefinition(..)
2604 | ForwardTyParamBanRibKind => {
2605 // Nothing to do. Continue.
2607 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2608 // This was an attempt to access an upvar inside a
2609 // named function item. This is not allowed, so we
2612 // We don't immediately trigger a resolve error, because
2613 // we want certain other resolution errors (namely those
2614 // emitted for `ConstantItemRibKind` below) to take
2616 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2619 ConstantItemRibKind(_, item) => {
2620 // Still doesn't deal with upvars
2622 let (span, resolution_error) =
2623 if let Some((ident, constant_item_kind)) = item {
2624 let kind_str = match constant_item_kind {
2625 ConstantItemKind::Const => "const",
2626 ConstantItemKind::Static => "static",
2630 AttemptToUseNonConstantValueInConstant(
2631 ident, "let", kind_str,
2637 AttemptToUseNonConstantValueInConstant(
2638 original_rib_ident_def,
2644 self.report_error(span, resolution_error);
2648 ConstParamTyRibKind => {
2650 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2656 if let Some(res_err) = res_err {
2657 self.report_error(span, res_err);
2661 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2662 let mut in_ty_param_default = false;
2664 let has_generic_params = match rib.kind {
2666 | ClosureOrAsyncRibKind
2669 | MacroDefinition(..) => {
2670 // Nothing to do. Continue.
2674 // We only forbid constant items if we are inside of type defaults,
2675 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2676 ForwardTyParamBanRibKind => {
2677 in_ty_param_default = true;
2680 ConstantItemRibKind(trivial, _) => {
2681 let features = self.session.features_untracked();
2682 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2684 || features.const_generics
2685 || features.lazy_normalization_consts)
2687 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2688 // we can't easily tell if it's generic at this stage, so we instead remember
2689 // this and then enforce the self type to be concrete later on.
2690 if let Res::SelfTy(trait_def, Some((impl_def, _))) = res {
2691 res = Res::SelfTy(trait_def, Some((impl_def, true)));
2696 ResolutionError::ParamInNonTrivialAnonConst {
2697 name: rib_ident.name,
2703 self.session.delay_span_bug(span, CG_BUG_STR);
2708 if in_ty_param_default {
2712 ResolutionError::ParamInAnonConstInTyDefault(
2723 // This was an attempt to use a type parameter outside its scope.
2724 ItemRibKind(has_generic_params) => has_generic_params,
2725 FnItemRibKind => HasGenericParams::Yes,
2726 ConstParamTyRibKind => {
2730 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2740 ResolutionError::GenericParamsFromOuterFunction(
2749 Res::Def(DefKind::ConstParam, _) => {
2750 let mut ribs = ribs.iter().peekable();
2751 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2752 // When declaring const parameters inside function signatures, the first rib
2753 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2754 // (spuriously) conflicting with the const param.
2758 let mut in_ty_param_default = false;
2760 let has_generic_params = match rib.kind {
2762 | ClosureOrAsyncRibKind
2765 | MacroDefinition(..) => continue,
2767 // We only forbid constant items if we are inside of type defaults,
2768 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2769 ForwardTyParamBanRibKind => {
2770 in_ty_param_default = true;
2773 ConstantItemRibKind(trivial, _) => {
2774 let features = self.session.features_untracked();
2775 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2777 || features.const_generics
2778 || features.lazy_normalization_consts)
2783 ResolutionError::ParamInNonTrivialAnonConst {
2784 name: rib_ident.name,
2790 self.session.delay_span_bug(span, CG_BUG_STR);
2794 if in_ty_param_default {
2798 ResolutionError::ParamInAnonConstInTyDefault(
2809 ItemRibKind(has_generic_params) => has_generic_params,
2810 FnItemRibKind => HasGenericParams::Yes,
2811 ConstParamTyRibKind => {
2815 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2822 // This was an attempt to use a const parameter outside its scope.
2826 ResolutionError::GenericParamsFromOuterFunction(
2840 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2841 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2842 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2843 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2847 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2848 vis.is_accessible_from(module.nearest_parent_mod, self)
2851 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2852 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2853 if !ptr::eq(module, old_module) {
2854 span_bug!(binding.span, "parent module is reset for binding");
2859 fn disambiguate_macro_rules_vs_modularized(
2861 macro_rules: &'a NameBinding<'a>,
2862 modularized: &'a NameBinding<'a>,
2864 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2865 // is disambiguated to mitigate regressions from macro modularization.
2866 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2868 self.binding_parent_modules.get(&PtrKey(macro_rules)),
2869 self.binding_parent_modules.get(&PtrKey(modularized)),
2871 (Some(macro_rules), Some(modularized)) => {
2872 macro_rules.nearest_parent_mod == modularized.nearest_parent_mod
2873 && modularized.is_ancestor_of(macro_rules)
2879 fn report_errors(&mut self, krate: &Crate) {
2880 self.report_with_use_injections(krate);
2882 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2883 let msg = "macro-expanded `macro_export` macros from the current crate \
2884 cannot be referred to by absolute paths";
2885 self.lint_buffer.buffer_lint_with_diagnostic(
2886 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2890 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2894 for ambiguity_error in &self.ambiguity_errors {
2895 self.report_ambiguity_error(ambiguity_error);
2898 let mut reported_spans = FxHashSet::default();
2899 for error in &self.privacy_errors {
2900 if reported_spans.insert(error.dedup_span) {
2901 self.report_privacy_error(error);
2906 fn report_with_use_injections(&mut self, krate: &Crate) {
2907 for UseError { mut err, candidates, def_id, instead, suggestion } in
2908 self.use_injections.drain(..)
2910 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
2911 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
2915 if !candidates.is_empty() {
2916 diagnostics::show_candidates(&mut err, span, &candidates, instead, found_use);
2917 } else if let Some((span, msg, sugg, appl)) = suggestion {
2918 err.span_suggestion(span, msg, sugg, appl);
2924 fn report_conflict<'b>(
2929 new_binding: &NameBinding<'b>,
2930 old_binding: &NameBinding<'b>,
2932 // Error on the second of two conflicting names
2933 if old_binding.span.lo() > new_binding.span.lo() {
2934 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2937 let container = match parent.kind {
2938 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id().unwrap()),
2939 ModuleKind::Block(..) => "block",
2942 let old_noun = match old_binding.is_import() {
2944 false => "definition",
2947 let new_participle = match new_binding.is_import() {
2953 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
2955 if let Some(s) = self.name_already_seen.get(&name) {
2961 let old_kind = match (ns, old_binding.module()) {
2962 (ValueNS, _) => "value",
2963 (MacroNS, _) => "macro",
2964 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2965 (TypeNS, Some(module)) if module.is_normal() => "module",
2966 (TypeNS, Some(module)) if module.is_trait() => "trait",
2967 (TypeNS, _) => "type",
2970 let msg = format!("the name `{}` is defined multiple times", name);
2972 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2973 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2974 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2975 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2976 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2978 _ => match (old_binding.is_import(), new_binding.is_import()) {
2979 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2980 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2981 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2986 "`{}` must be defined only once in the {} namespace of this {}",
2992 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2994 self.session.source_map().guess_head_span(old_binding.span),
2995 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2998 // See https://github.com/rust-lang/rust/issues/32354
2999 use NameBindingKind::Import;
3000 let import = match (&new_binding.kind, &old_binding.kind) {
3001 // If there are two imports where one or both have attributes then prefer removing the
3002 // import without attributes.
3003 (Import { import: new, .. }, Import { import: old, .. })
3005 !new_binding.span.is_dummy()
3006 && !old_binding.span.is_dummy()
3007 && (new.has_attributes || old.has_attributes)
3010 if old.has_attributes {
3011 Some((new, new_binding.span, true))
3013 Some((old, old_binding.span, true))
3016 // Otherwise prioritize the new binding.
3017 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
3018 Some((import, new_binding.span, other.is_import()))
3020 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
3021 Some((import, old_binding.span, other.is_import()))
3026 // Check if the target of the use for both bindings is the same.
3027 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
3028 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
3030 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
3031 // Only suggest removing an import if both bindings are to the same def, if both spans
3032 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
3033 // been introduced by a item.
3034 let should_remove_import = duplicate
3036 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
3039 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3040 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3042 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3043 // Simple case - remove the entire import. Due to the above match arm, this can
3044 // only be a single use so just remove it entirely.
3045 err.tool_only_span_suggestion(
3046 import.use_span_with_attributes,
3047 "remove unnecessary import",
3049 Applicability::MaybeIncorrect,
3052 Some((import, span, _)) => {
3053 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3059 self.name_already_seen.insert(name, span);
3062 /// This function adds a suggestion to change the binding name of a new import that conflicts
3063 /// with an existing import.
3065 /// ```text,ignore (diagnostic)
3066 /// help: you can use `as` to change the binding name of the import
3068 /// LL | use foo::bar as other_bar;
3069 /// | ^^^^^^^^^^^^^^^^^^^^^
3071 fn add_suggestion_for_rename_of_use(
3073 err: &mut DiagnosticBuilder<'_>,
3075 import: &Import<'_>,
3078 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3079 format!("Other{}", name)
3081 format!("other_{}", name)
3084 let mut suggestion = None;
3086 ImportKind::Single { type_ns_only: true, .. } => {
3087 suggestion = Some(format!("self as {}", suggested_name))
3089 ImportKind::Single { source, .. } => {
3091 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3093 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3094 if pos <= snippet.len() {
3095 suggestion = Some(format!(
3099 if snippet.ends_with(';') { ";" } else { "" }
3105 ImportKind::ExternCrate { source, target, .. } => {
3106 suggestion = Some(format!(
3107 "extern crate {} as {};",
3108 source.unwrap_or(target.name),
3112 _ => unreachable!(),
3115 let rename_msg = "you can use `as` to change the binding name of the import";
3116 if let Some(suggestion) = suggestion {
3117 err.span_suggestion(
3121 Applicability::MaybeIncorrect,
3124 err.span_label(binding_span, rename_msg);
3128 /// This function adds a suggestion to remove a unnecessary binding from an import that is
3129 /// nested. In the following example, this function will be invoked to remove the `a` binding
3130 /// in the second use statement:
3132 /// ```ignore (diagnostic)
3133 /// use issue_52891::a;
3134 /// use issue_52891::{d, a, e};
3137 /// The following suggestion will be added:
3139 /// ```ignore (diagnostic)
3140 /// use issue_52891::{d, a, e};
3141 /// ^-- help: remove unnecessary import
3144 /// If the nested use contains only one import then the suggestion will remove the entire
3147 /// It is expected that the provided import is nested - this isn't checked by the
3148 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3149 /// as characters expected by span manipulations won't be present.
3150 fn add_suggestion_for_duplicate_nested_use(
3152 err: &mut DiagnosticBuilder<'_>,
3153 import: &Import<'_>,
3156 assert!(import.is_nested());
3157 let message = "remove unnecessary import";
3159 // Two examples will be used to illustrate the span manipulations we're doing:
3161 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3162 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3163 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3164 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3166 let (found_closing_brace, span) =
3167 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3169 // If there was a closing brace then identify the span to remove any trailing commas from
3170 // previous imports.
3171 if found_closing_brace {
3172 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3173 err.tool_only_span_suggestion(
3177 Applicability::MaybeIncorrect,
3180 // Remove the entire line if we cannot extend the span back, this indicates a
3181 // `issue_52891::{self}` case.
3182 err.span_suggestion(
3183 import.use_span_with_attributes,
3186 Applicability::MaybeIncorrect,
3193 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3196 fn extern_prelude_get(
3200 ) -> Option<&'a NameBinding<'a>> {
3201 if ident.is_path_segment_keyword() {
3202 // Make sure `self`, `super` etc produce an error when passed to here.
3205 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3206 if let Some(binding) = entry.extern_crate_item {
3207 if !speculative && entry.introduced_by_item {
3208 self.record_use(ident, TypeNS, binding, false);
3212 let crate_id = if !speculative {
3213 self.crate_loader.process_path_extern(ident.name, ident.span)
3215 self.crate_loader.maybe_process_path_extern(ident.name)?
3217 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
3219 (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
3220 .to_name_binding(self.arenas),
3226 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3227 /// isn't something that can be returned because it can't be made to live that long,
3228 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3229 /// just that an error occurred.
3230 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3231 pub fn resolve_str_path_error(
3237 ) -> Result<(ast::Path, Res), ()> {
3238 let path = if path_str.starts_with("::") {
3241 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3242 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3243 .map(|i| self.new_ast_path_segment(i))
3252 .map(Ident::from_str)
3253 .map(|i| self.new_ast_path_segment(i))
3258 let module = self.get_module(module_id);
3259 let parent_scope = &ParentScope::module(module, self);
3260 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3264 // Resolve a path passed from rustdoc or HIR lowering.
3265 fn resolve_ast_path(
3269 parent_scope: &ParentScope<'a>,
3270 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3271 match self.resolve_path(
3272 &Segment::from_path(path),
3279 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3280 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3281 Ok(path_res.base_res())
3283 PathResult::NonModule(..) => Err((
3285 ResolutionError::FailedToResolve {
3286 label: String::from("type-relative paths are not supported in this context"),
3290 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3291 PathResult::Failed { span, label, suggestion, .. } => {
3292 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3297 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3298 let mut seg = ast::PathSegment::from_ident(ident);
3299 seg.id = self.next_node_id();
3304 pub fn graph_root(&self) -> Module<'a> {
3309 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3313 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3315 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3316 if let Some(def_id) = def_id.as_local() { Some(self.def_id_to_span[def_id]) } else { None }
3320 fn names_to_string(names: &[Symbol]) -> String {
3321 let mut result = String::new();
3322 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3324 result.push_str("::");
3326 if Ident::with_dummy_span(*name).is_raw_guess() {
3327 result.push_str("r#");
3329 result.push_str(&name.as_str());
3334 fn path_names_to_string(path: &Path) -> String {
3335 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3338 /// A somewhat inefficient routine to obtain the name of a module.
3339 fn module_to_string(module: Module<'_>) -> Option<String> {
3340 let mut names = Vec::new();
3342 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3343 if let ModuleKind::Def(.., name) = module.kind {
3344 if let Some(parent) = module.parent {
3346 collect_mod(names, parent);
3349 names.push(Symbol::intern("<opaque>"));
3350 collect_mod(names, module.parent.unwrap());
3353 collect_mod(&mut names, module);
3355 if names.is_empty() {
3359 Some(names_to_string(&names))
3362 #[derive(Copy, Clone, Debug)]
3364 /// Do not issue the lint.
3367 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3368 /// In this case, we can take the span of that path.
3371 /// This lint comes from a `use` statement. In this case, what we
3372 /// care about really is the *root* `use` statement; e.g., if we
3373 /// have nested things like `use a::{b, c}`, we care about the
3375 UsePath { root_id: NodeId, root_span: Span },
3377 /// This is the "trait item" from a fully qualified path. For example,
3378 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3379 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3380 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3384 fn node_id(&self) -> Option<NodeId> {
3386 CrateLint::No => None,
3387 CrateLint::SimplePath(id)
3388 | CrateLint::UsePath { root_id: id, .. }
3389 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3394 pub fn provide(providers: &mut Providers) {
3395 late::lifetimes::provide(providers);