1 // ignore-tidy-filelength
3 //! This crate is responsible for the part of name resolution that doesn't require type checker.
5 //! Module structure of the crate is built here.
6 //! Paths in macros, imports, expressions, types, patterns are resolved here.
7 //! Label and lifetime names are resolved here as well.
9 //! Type-relative name resolution (methods, fields, associated items) happens in `librustc_typeck`.
11 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
12 #![feature(box_patterns)]
13 #![feature(bool_to_option)]
14 #![feature(control_flow_enum)]
15 #![feature(crate_visibility_modifier)]
16 #![feature(format_args_capture)]
19 #![cfg_attr(bootstrap, feature(or_patterns))]
20 #![recursion_limit = "256"]
22 pub use rustc_hir::def::{Namespace, PerNS};
26 use rustc_arena::{DroplessArena, TypedArena};
27 use rustc_ast::node_id::NodeMap;
28 use rustc_ast::ptr::P;
29 use rustc_ast::visit::{self, Visitor};
30 use rustc_ast::{self as ast, NodeId};
31 use rustc_ast::{Crate, CRATE_NODE_ID};
32 use rustc_ast::{Expr, ExprKind, LitKind};
33 use rustc_ast::{ItemKind, ModKind, Path};
34 use rustc_ast_lowering::ResolverAstLowering;
35 use rustc_ast_pretty::pprust;
36 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
37 use rustc_data_structures::ptr_key::PtrKey;
38 use rustc_data_structures::sync::Lrc;
39 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
40 use rustc_expand::base::{DeriveResolutions, SyntaxExtension, SyntaxExtensionKind};
41 use rustc_hir::def::Namespace::*;
42 use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes};
43 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
44 use rustc_hir::definitions::{DefKey, DefPathData, Definitions};
45 use rustc_hir::TraitCandidate;
46 use rustc_index::vec::IndexVec;
47 use rustc_metadata::creader::{CStore, CrateLoader};
48 use rustc_middle::hir::exports::ExportMap;
49 use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn};
50 use rustc_middle::span_bug;
51 use rustc_middle::ty::query::Providers;
52 use rustc_middle::ty::{self, DefIdTree, ResolverOutputs};
53 use rustc_session::lint;
54 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
55 use rustc_session::Session;
56 use rustc_span::edition::Edition;
57 use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency};
58 use rustc_span::source_map::Spanned;
59 use rustc_span::symbol::{kw, sym, Ident, Symbol};
60 use rustc_span::{Span, DUMMY_SP};
62 use smallvec::{smallvec, SmallVec};
63 use std::cell::{Cell, RefCell};
64 use std::collections::BTreeSet;
65 use std::ops::ControlFlow;
66 use std::{cmp, fmt, iter, ptr};
69 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
70 use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion};
71 use imports::{Import, ImportKind, ImportResolver, NameResolution};
72 use late::{ConstantItemKind, HasGenericParams, PathSource, Rib, RibKind::*};
73 use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
75 type Res = def::Res<NodeId>;
77 mod build_reduced_graph;
90 #[derive(Copy, Clone, PartialEq, Debug)]
91 pub enum Determinacy {
97 fn determined(determined: bool) -> Determinacy {
98 if determined { Determinacy::Determined } else { Determinacy::Undetermined }
102 /// A specific scope in which a name can be looked up.
103 /// This enum is currently used only for early resolution (imports and macros),
104 /// but not for late resolution yet.
105 #[derive(Clone, Copy)]
107 DeriveHelpers(ExpnId),
109 MacroRules(MacroRulesScopeRef<'a>),
111 // The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
112 // lint if it should be reported.
113 Module(Module<'a>, Option<NodeId>),
123 /// Names from different contexts may want to visit different subsets of all specific scopes
124 /// with different restrictions when looking up the resolution.
125 /// This enum is currently used only for early resolution (imports and macros),
126 /// but not for late resolution yet.
127 #[derive(Clone, Copy)]
129 /// All scopes with the given namespace.
130 All(Namespace, /*is_import*/ bool),
131 /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros).
132 AbsolutePath(Namespace),
133 /// All scopes with macro namespace and the given macro kind restriction.
135 /// All scopes with the given namespace, used for partially performing late resolution.
136 /// The node id enables lints and is used for reporting them.
137 Late(Namespace, Module<'a>, Option<NodeId>),
140 /// Everything you need to know about a name's location to resolve it.
141 /// Serves as a starting point for the scope visitor.
142 /// This struct is currently used only for early resolution (imports and macros),
143 /// but not for late resolution yet.
144 #[derive(Clone, Copy, Debug)]
145 pub struct ParentScope<'a> {
148 macro_rules: MacroRulesScopeRef<'a>,
149 derives: &'a [ast::Path],
152 impl<'a> ParentScope<'a> {
153 /// Creates a parent scope with the passed argument used as the module scope component,
154 /// and other scope components set to default empty values.
155 pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> {
158 expansion: ExpnId::root(),
159 macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty),
165 #[derive(Copy, Debug, Clone)]
166 enum ImplTraitContext {
168 Universal(LocalDefId),
172 struct BindingError {
174 origin: BTreeSet<Span>,
175 target: BTreeSet<Span>,
179 impl PartialOrd for BindingError {
180 fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
181 Some(self.cmp(other))
185 impl PartialEq for BindingError {
186 fn eq(&self, other: &BindingError) -> bool {
187 self.name == other.name
191 impl Ord for BindingError {
192 fn cmp(&self, other: &BindingError) -> cmp::Ordering {
193 self.name.cmp(&other.name)
197 enum ResolutionError<'a> {
198 /// Error E0401: can't use type or const parameters from outer function.
199 GenericParamsFromOuterFunction(Res, HasGenericParams),
200 /// Error E0403: the name is already used for a type or const parameter in this generic
202 NameAlreadyUsedInParameterList(Symbol, Span),
203 /// Error E0407: method is not a member of trait.
204 MethodNotMemberOfTrait(Symbol, &'a str),
205 /// Error E0437: type is not a member of trait.
206 TypeNotMemberOfTrait(Symbol, &'a str),
207 /// Error E0438: const is not a member of trait.
208 ConstNotMemberOfTrait(Symbol, &'a str),
209 /// Error E0408: variable `{}` is not bound in all patterns.
210 VariableNotBoundInPattern(&'a BindingError),
211 /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
212 VariableBoundWithDifferentMode(Symbol, Span),
213 /// Error E0415: identifier is bound more than once in this parameter list.
214 IdentifierBoundMoreThanOnceInParameterList(Symbol),
215 /// Error E0416: identifier is bound more than once in the same pattern.
216 IdentifierBoundMoreThanOnceInSamePattern(Symbol),
217 /// Error E0426: use of undeclared label.
218 UndeclaredLabel { name: Symbol, suggestion: Option<LabelSuggestion> },
219 /// Error E0429: `self` imports are only allowed within a `{ }` list.
220 SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span },
221 /// Error E0430: `self` import can only appear once in the list.
222 SelfImportCanOnlyAppearOnceInTheList,
223 /// Error E0431: `self` import can only appear in an import list with a non-empty prefix.
224 SelfImportOnlyInImportListWithNonEmptyPrefix,
225 /// Error E0433: failed to resolve.
226 FailedToResolve { label: String, suggestion: Option<Suggestion> },
227 /// Error E0434: can't capture dynamic environment in a fn item.
228 CannotCaptureDynamicEnvironmentInFnItem,
229 /// Error E0435: attempt to use a non-constant value in a constant.
230 AttemptToUseNonConstantValueInConstant(
232 /* suggestion */ &'static str,
233 /* current */ &'static str,
235 /// Error E0530: `X` bindings cannot shadow `Y`s.
236 BindingShadowsSomethingUnacceptable(&'static str, Symbol, &'a NameBinding<'a>),
237 /// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
238 ForwardDeclaredTyParam, // FIXME(const_generics_defaults)
239 /// ERROR E0770: the type of const parameters must not depend on other generic parameters.
240 ParamInTyOfConstParam(Symbol),
241 /// constant values inside of type parameter defaults must not depend on generic parameters.
242 ParamInAnonConstInTyDefault(Symbol),
243 /// generic parameters must not be used inside const evaluations.
245 /// This error is only emitted when using `min_const_generics`.
246 ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
247 /// Error E0735: generic parameters with a default cannot use `Self`
248 SelfInTyParamDefault,
249 /// Error E0767: use of unreachable label
250 UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
253 enum VisResolutionError<'a> {
254 Relative2018(Span, &'a ast::Path),
256 FailedToResolve(Span, String, Option<Suggestion>),
257 ExpectedFound(Span, String, Res),
262 /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path
263 /// segments' which don't have the rest of an AST or HIR `PathSegment`.
264 #[derive(Clone, Copy, Debug)]
268 /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing
269 /// nonsensical suggestions.
270 has_generic_args: bool,
274 fn from_path(path: &Path) -> Vec<Segment> {
275 path.segments.iter().map(|s| s.into()).collect()
278 fn from_ident(ident: Ident) -> Segment {
279 Segment { ident, id: None, has_generic_args: false }
282 fn names_to_string(segments: &[Segment]) -> String {
283 names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
287 impl<'a> From<&'a ast::PathSegment> for Segment {
288 fn from(seg: &'a ast::PathSegment) -> Segment {
289 Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() }
293 struct UsePlacementFinder {
294 target_module: NodeId,
299 impl UsePlacementFinder {
300 fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
301 let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
302 if let ControlFlow::Continue(..) = finder.check_mod(&krate.items, CRATE_NODE_ID) {
303 visit::walk_crate(&mut finder, krate);
305 (finder.span, finder.found_use)
308 fn check_mod(&mut self, items: &[P<ast::Item>], node_id: NodeId) -> ControlFlow<()> {
309 if self.span.is_some() {
310 return ControlFlow::Break(());
312 if node_id != self.target_module {
313 return ControlFlow::Continue(());
315 // find a use statement
318 ItemKind::Use(..) => {
319 // don't suggest placing a use before the prelude
320 // import or other generated ones
321 if !item.span.from_expansion() {
322 self.span = Some(item.span.shrink_to_lo());
323 self.found_use = true;
324 return ControlFlow::Break(());
327 // don't place use before extern crate
328 ItemKind::ExternCrate(_) => {}
329 // but place them before the first other item
331 if self.span.map_or(true, |span| item.span < span)
332 && !item.span.from_expansion()
334 // don't insert between attributes and an item
335 if item.attrs.is_empty() {
336 self.span = Some(item.span.shrink_to_lo());
338 // find the first attribute on the item
339 for attr in &item.attrs {
340 if self.span.map_or(true, |span| attr.span < span) {
341 self.span = Some(attr.span.shrink_to_lo());
349 ControlFlow::Continue(())
353 impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
354 fn visit_item(&mut self, item: &'tcx ast::Item) {
355 if let ItemKind::Mod(_, ModKind::Loaded(items, ..)) = &item.kind {
356 if let ControlFlow::Break(..) = self.check_mod(items, item.id) {
360 visit::walk_item(self, item);
364 /// An intermediate resolution result.
366 /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that
367 /// items are visible in their whole block, while `Res`es only from the place they are defined
370 enum LexicalScopeBinding<'a> {
371 Item(&'a NameBinding<'a>),
375 impl<'a> LexicalScopeBinding<'a> {
376 fn res(self) -> Res {
378 LexicalScopeBinding::Item(binding) => binding.res(),
379 LexicalScopeBinding::Res(res) => res,
384 #[derive(Copy, Clone, Debug)]
385 enum ModuleOrUniformRoot<'a> {
389 /// Virtual module that denotes resolution in crate root with fallback to extern prelude.
390 CrateRootAndExternPrelude,
392 /// Virtual module that denotes resolution in extern prelude.
393 /// Used for paths starting with `::` on 2018 edition.
396 /// Virtual module that denotes resolution in current scope.
397 /// Used only for resolving single-segment imports. The reason it exists is that import paths
398 /// are always split into two parts, the first of which should be some kind of module.
402 impl ModuleOrUniformRoot<'_> {
403 fn same_def(lhs: Self, rhs: Self) -> bool {
405 (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => {
406 lhs.def_id() == rhs.def_id()
409 ModuleOrUniformRoot::CrateRootAndExternPrelude,
410 ModuleOrUniformRoot::CrateRootAndExternPrelude,
412 | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude)
413 | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true,
419 #[derive(Clone, Debug)]
420 enum PathResult<'a> {
421 Module(ModuleOrUniformRoot<'a>),
422 NonModule(PartialRes),
427 suggestion: Option<Suggestion>,
428 is_error_from_last_segment: bool,
434 /// An anonymous module; e.g., just a block.
439 /// { // This is an anonymous module
440 /// f(); // This resolves to (2) as we are inside the block.
443 /// f(); // Resolves to (1)
447 /// Any module with a name.
451 /// * A normal module – either `mod from_file;` or `mod from_block { }` –
452 /// or the crate root (which is conceptually a top-level module).
453 /// Note that the crate root's [name][Self::name] will be [`kw::Empty`].
454 /// * A trait or an enum (it implicitly contains associated types, methods and variant
456 Def(DefKind, DefId, Symbol),
460 /// Get name of the module.
461 pub fn name(&self) -> Option<Symbol> {
463 ModuleKind::Block(..) => None,
464 ModuleKind::Def(.., name) => Some(*name),
469 /// A key that identifies a binding in a given `Module`.
471 /// Multiple bindings in the same module can have the same key (in a valid
472 /// program) if all but one of them come from glob imports.
473 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
475 /// The identifier for the binding, aways the `normalize_to_macros_2_0` version of the
479 /// 0 if ident is not `_`, otherwise a value that's unique to the specific
480 /// `_` in the expanded AST that introduced this binding.
484 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
486 /// One node in the tree of modules.
488 /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these:
491 /// * crate root (aka, top-level anonymous module)
494 /// * curly-braced block with statements
496 /// You can use [`ModuleData::kind`] to determine the kind of module this is.
497 pub struct ModuleData<'a> {
498 /// The direct parent module (it may not be a `mod`, however).
499 parent: Option<Module<'a>>,
500 /// What kind of module this is, because this may not be a `mod`.
503 /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module).
504 /// This may be the crate root.
505 nearest_parent_mod: DefId,
507 /// Mapping between names and their (possibly in-progress) resolutions in this module.
508 /// Resolutions in modules from other crates are not populated until accessed.
509 lazy_resolutions: Resolutions<'a>,
510 /// True if this is a module from other crate that needs to be populated on access.
511 populate_on_access: Cell<bool>,
513 /// Macro invocations that can expand into items in this module.
514 unexpanded_invocations: RefCell<FxHashSet<ExpnId>>,
516 /// Whether `#[no_implicit_prelude]` is active.
517 no_implicit_prelude: bool,
519 glob_importers: RefCell<Vec<&'a Import<'a>>>,
520 globs: RefCell<Vec<&'a Import<'a>>>,
522 /// Used to memoize the traits in this module for faster searches through all traits in scope.
523 traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
525 /// Span of the module itself. Used for error reporting.
531 type Module<'a> = &'a ModuleData<'a>;
533 impl<'a> ModuleData<'a> {
535 parent: Option<Module<'a>>,
537 nearest_parent_mod: DefId,
545 lazy_resolutions: Default::default(),
546 populate_on_access: Cell::new(!nearest_parent_mod.is_local()),
547 unexpanded_invocations: Default::default(),
548 no_implicit_prelude: false,
549 glob_importers: RefCell::new(Vec::new()),
550 globs: RefCell::new(Vec::new()),
551 traits: RefCell::new(None),
557 fn for_each_child<R, F>(&'a self, resolver: &mut R, mut f: F)
559 R: AsMut<Resolver<'a>>,
560 F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>),
562 for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() {
563 if let Some(binding) = name_resolution.borrow().binding {
564 f(resolver, key.ident, key.ns, binding);
569 /// This modifies `self` in place. The traits will be stored in `self.traits`.
570 fn ensure_traits<R>(&'a self, resolver: &mut R)
572 R: AsMut<Resolver<'a>>,
574 let mut traits = self.traits.borrow_mut();
575 if traits.is_none() {
576 let mut collected_traits = Vec::new();
577 self.for_each_child(resolver, |_, name, ns, binding| {
581 if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() {
582 collected_traits.push((name, binding))
585 *traits = Some(collected_traits.into_boxed_slice());
589 fn res(&self) -> Option<Res> {
591 ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)),
596 fn def_id(&self) -> Option<DefId> {
598 ModuleKind::Def(_, def_id, _) => Some(def_id),
603 // `self` resolves to the first module ancestor that `is_normal`.
604 fn is_normal(&self) -> bool {
605 matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _))
608 fn is_trait(&self) -> bool {
609 matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _))
612 fn nearest_item_scope(&'a self) -> Module<'a> {
614 ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => {
615 self.parent.expect("enum or trait module without a parent")
621 fn is_ancestor_of(&self, mut other: &Self) -> bool {
622 while !ptr::eq(self, other) {
623 if let Some(parent) = other.parent {
633 impl<'a> fmt::Debug for ModuleData<'a> {
634 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
635 write!(f, "{:?}", self.res())
639 /// Records a possibly-private value, type, or module definition.
640 #[derive(Clone, Debug)]
641 pub struct NameBinding<'a> {
642 kind: NameBindingKind<'a>,
643 ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>,
649 pub trait ToNameBinding<'a> {
650 fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
653 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
654 fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
659 #[derive(Clone, Debug)]
660 enum NameBindingKind<'a> {
661 Res(Res, /* is_macro_export */ bool),
663 Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell<bool> },
666 impl<'a> NameBindingKind<'a> {
667 /// Is this a name binding of a import?
668 fn is_import(&self) -> bool {
669 matches!(*self, NameBindingKind::Import { .. })
673 struct PrivacyError<'a> {
675 binding: &'a NameBinding<'a>,
679 struct UseError<'a> {
680 err: DiagnosticBuilder<'a>,
681 /// Candidates which user could `use` to access the missing type.
682 candidates: Vec<ImportSuggestion>,
683 /// The `DefId` of the module to place the use-statements in.
685 /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`).
687 /// Extra free-form suggestion.
688 suggestion: Option<(Span, &'static str, String, Applicability)>,
691 #[derive(Clone, Copy, PartialEq, Debug)]
696 MacroRulesVsModularized,
704 fn descr(self) -> &'static str {
706 AmbiguityKind::Import => "name vs any other name during import resolution",
707 AmbiguityKind::BuiltinAttr => "built-in attribute vs any other name",
708 AmbiguityKind::DeriveHelper => "derive helper attribute vs any other name",
709 AmbiguityKind::MacroRulesVsModularized => {
710 "`macro_rules` vs non-`macro_rules` from other module"
712 AmbiguityKind::GlobVsOuter => {
713 "glob import vs any other name from outer scope during import/macro resolution"
715 AmbiguityKind::GlobVsGlob => "glob import vs glob import in the same module",
716 AmbiguityKind::GlobVsExpanded => {
717 "glob import vs macro-expanded name in the same \
718 module during import/macro resolution"
720 AmbiguityKind::MoreExpandedVsOuter => {
721 "macro-expanded name vs less macro-expanded name \
722 from outer scope during import/macro resolution"
728 /// Miscellaneous bits of metadata for better ambiguity error reporting.
729 #[derive(Clone, Copy, PartialEq)]
730 enum AmbiguityErrorMisc {
737 struct AmbiguityError<'a> {
740 b1: &'a NameBinding<'a>,
741 b2: &'a NameBinding<'a>,
742 misc1: AmbiguityErrorMisc,
743 misc2: AmbiguityErrorMisc,
746 impl<'a> NameBinding<'a> {
747 fn module(&self) -> Option<Module<'a>> {
749 NameBindingKind::Module(module) => Some(module),
750 NameBindingKind::Import { binding, .. } => binding.module(),
755 fn res(&self) -> Res {
757 NameBindingKind::Res(res, _) => res,
758 NameBindingKind::Module(module) => module.res().unwrap(),
759 NameBindingKind::Import { binding, .. } => binding.res(),
763 fn is_ambiguity(&self) -> bool {
764 self.ambiguity.is_some()
766 NameBindingKind::Import { binding, .. } => binding.is_ambiguity(),
771 fn is_possibly_imported_variant(&self) -> bool {
773 NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(),
774 NameBindingKind::Res(
775 Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _),
778 NameBindingKind::Res(..) | NameBindingKind::Module(..) => false,
782 fn is_extern_crate(&self) -> bool {
784 NameBindingKind::Import {
785 import: &Import { kind: ImportKind::ExternCrate { .. }, .. },
788 NameBindingKind::Module(&ModuleData {
789 kind: ModuleKind::Def(DefKind::Mod, def_id, _),
791 }) => def_id.index == CRATE_DEF_INDEX,
796 fn is_import(&self) -> bool {
797 matches!(self.kind, NameBindingKind::Import { .. })
800 fn is_glob_import(&self) -> bool {
802 NameBindingKind::Import { import, .. } => import.is_glob(),
807 fn is_importable(&self) -> bool {
810 Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
814 fn is_macro_def(&self) -> bool {
815 matches!(self.kind, NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _))
818 fn macro_kind(&self) -> Option<MacroKind> {
819 self.res().macro_kind()
822 // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
823 // at some expansion round `max(invoc, binding)` when they both emerged from macros.
824 // Then this function returns `true` if `self` may emerge from a macro *after* that
825 // in some later round and screw up our previously found resolution.
826 // See more detailed explanation in
827 // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
828 fn may_appear_after(&self, invoc_parent_expansion: ExpnId, binding: &NameBinding<'_>) -> bool {
829 // self > max(invoc, binding) => !(self <= invoc || self <= binding)
830 // Expansions are partially ordered, so "may appear after" is an inversion of
831 // "certainly appears before or simultaneously" and includes unordered cases.
832 let self_parent_expansion = self.expansion;
833 let other_parent_expansion = binding.expansion;
834 let certainly_before_other_or_simultaneously =
835 other_parent_expansion.is_descendant_of(self_parent_expansion);
836 let certainly_before_invoc_or_simultaneously =
837 invoc_parent_expansion.is_descendant_of(self_parent_expansion);
838 !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously)
842 #[derive(Debug, Default, Clone)]
843 pub struct ExternPreludeEntry<'a> {
844 extern_crate_item: Option<&'a NameBinding<'a>>,
845 pub introduced_by_item: bool,
848 /// Used for better errors for E0773
849 enum BuiltinMacroState {
850 NotYetSeen(SyntaxExtensionKind),
855 resolutions: DeriveResolutions,
856 helper_attrs: Vec<Ident>,
857 has_derive_copy: bool,
860 /// The main resolver class.
862 /// This is the visitor that walks the whole crate.
863 pub struct Resolver<'a> {
864 session: &'a Session,
866 definitions: Definitions,
868 graph_root: Module<'a>,
870 prelude: Option<Module<'a>>,
871 extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>,
873 /// N.B., this is used only for better diagnostics, not name resolution itself.
874 has_self: FxHashSet<DefId>,
876 /// Names of fields of an item `DefId` accessible with dot syntax.
877 /// Used for hints during error reporting.
878 field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>,
880 /// All imports known to succeed or fail.
881 determined_imports: Vec<&'a Import<'a>>,
883 /// All non-determined imports.
884 indeterminate_imports: Vec<&'a Import<'a>>,
886 /// FIXME: Refactor things so that these fields are passed through arguments and not resolver.
887 /// We are resolving a last import segment during import validation.
888 last_import_segment: bool,
889 /// This binding should be ignored during in-module resolution, so that we don't get
890 /// "self-confirming" import resolutions during import validation.
891 unusable_binding: Option<&'a NameBinding<'a>>,
893 /// Resolutions for nodes that have a single resolution.
894 partial_res_map: NodeMap<PartialRes>,
895 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
896 import_res_map: NodeMap<PerNS<Option<Res>>>,
897 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
898 label_res_map: NodeMap<NodeId>,
900 /// `CrateNum` resolutions of `extern crate` items.
901 extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
902 export_map: ExportMap<LocalDefId>,
903 trait_map: NodeMap<Vec<TraitCandidate>>,
905 /// A map from nodes to anonymous modules.
906 /// Anonymous modules are pseudo-modules that are implicitly created around items
907 /// contained within blocks.
909 /// For example, if we have this:
917 /// There will be an anonymous module created around `g` with the ID of the
918 /// entry block for `f`.
919 block_map: NodeMap<Module<'a>>,
920 /// A fake module that contains no definition and no prelude. Used so that
921 /// some AST passes can generate identifiers that only resolve to local or
923 empty_module: Module<'a>,
924 module_map: FxHashMap<LocalDefId, Module<'a>>,
925 extern_module_map: FxHashMap<DefId, Module<'a>>,
926 binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>,
927 underscore_disambiguator: u32,
929 /// Maps glob imports to the names of items actually imported.
930 glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
931 /// Visibilities in "lowered" form, for all entities that have them.
932 visibilities: FxHashMap<LocalDefId, ty::Visibility>,
933 used_imports: FxHashSet<(NodeId, Namespace)>,
934 maybe_unused_trait_imports: FxHashSet<LocalDefId>,
935 maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
937 /// Privacy errors are delayed until the end in order to deduplicate them.
938 privacy_errors: Vec<PrivacyError<'a>>,
939 /// Ambiguity errors are delayed for deduplication.
940 ambiguity_errors: Vec<AmbiguityError<'a>>,
941 /// `use` injections are delayed for better placement and deduplication.
942 use_injections: Vec<UseError<'a>>,
943 /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
944 macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
946 arenas: &'a ResolverArenas<'a>,
947 dummy_binding: &'a NameBinding<'a>,
949 crate_loader: CrateLoader<'a>,
950 macro_names: FxHashSet<Ident>,
951 builtin_macros: FxHashMap<Symbol, BuiltinMacroState>,
952 registered_attrs: FxHashSet<Ident>,
953 registered_tools: FxHashSet<Ident>,
954 macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>,
955 all_macros: FxHashMap<Symbol, Res>,
956 macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>,
957 dummy_ext_bang: Lrc<SyntaxExtension>,
958 dummy_ext_derive: Lrc<SyntaxExtension>,
959 non_macro_attrs: [Lrc<SyntaxExtension>; 2],
960 local_macro_def_scopes: FxHashMap<LocalDefId, Module<'a>>,
961 ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>,
962 unused_macros: FxHashMap<LocalDefId, (NodeId, Span)>,
963 proc_macro_stubs: FxHashSet<LocalDefId>,
964 /// Traces collected during macro resolution and validated when it's complete.
965 single_segment_macro_resolutions:
966 Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>,
967 multi_segment_macro_resolutions:
968 Vec<(Vec<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>,
969 builtin_attrs: Vec<(Ident, ParentScope<'a>)>,
970 /// `derive(Copy)` marks items they are applied to so they are treated specially later.
971 /// Derive macros cannot modify the item themselves and have to store the markers in the global
972 /// context, so they attach the markers to derive container IDs using this resolver table.
973 containers_deriving_copy: FxHashSet<ExpnId>,
974 /// Parent scopes in which the macros were invoked.
975 /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere.
976 invocation_parent_scopes: FxHashMap<ExpnId, ParentScope<'a>>,
977 /// `macro_rules` scopes *produced* by expanding the macro invocations,
978 /// include all the `macro_rules` items and other invocations generated by them.
979 output_macro_rules_scopes: FxHashMap<ExpnId, MacroRulesScopeRef<'a>>,
980 /// Helper attributes that are in scope for the given expansion.
981 helper_attrs: FxHashMap<ExpnId, Vec<Ident>>,
982 /// Ready or in-progress results of resolving paths inside the `#[derive(...)]` attribute
983 /// with the given `ExpnId`.
984 derive_data: FxHashMap<ExpnId, DeriveData>,
986 /// Avoid duplicated errors for "name already defined".
987 name_already_seen: FxHashMap<Symbol, Span>,
989 potentially_unused_imports: Vec<&'a Import<'a>>,
991 /// Table for mapping struct IDs into struct constructor IDs,
992 /// it's not used during normal resolution, only for better error reporting.
993 /// Also includes of list of each fields visibility
994 struct_constructors: DefIdMap<(Res, ty::Visibility, Vec<ty::Visibility>)>,
996 /// Features enabled for this crate.
997 active_features: FxHashSet<Symbol>,
999 lint_buffer: LintBuffer,
1001 next_node_id: NodeId,
1003 def_id_to_span: IndexVec<LocalDefId, Span>,
1005 node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
1006 def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
1008 /// Indices of unnamed struct or variant fields with unresolved attributes.
1009 placeholder_field_indices: FxHashMap<NodeId, usize>,
1010 /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId`
1011 /// we know what parent node that fragment should be attached to thanks to this table,
1012 /// and how the `impl Trait` fragments were introduced.
1013 invocation_parents: FxHashMap<ExpnId, (LocalDefId, ImplTraitContext)>,
1015 next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>,
1016 /// Some way to know that we are in a *trait* impl in `visit_assoc_item`.
1017 /// FIXME: Replace with a more general AST map (together with some other fields).
1018 trait_impl_items: FxHashSet<LocalDefId>,
1020 legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
1023 /// Nothing really interesting here; it just provides memory for the rest of the crate.
1025 pub struct ResolverArenas<'a> {
1026 modules: TypedArena<ModuleData<'a>>,
1027 local_modules: RefCell<Vec<Module<'a>>>,
1028 imports: TypedArena<Import<'a>>,
1029 name_resolutions: TypedArena<RefCell<NameResolution<'a>>>,
1030 ast_paths: TypedArena<ast::Path>,
1031 dropless: DroplessArena,
1034 impl<'a> ResolverArenas<'a> {
1035 fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1036 let module = self.modules.alloc(module);
1037 if module.def_id().map_or(true, |def_id| def_id.is_local()) {
1038 self.local_modules.borrow_mut().push(module);
1042 fn local_modules(&'a self) -> std::cell::Ref<'a, Vec<Module<'a>>> {
1043 self.local_modules.borrow()
1045 fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1046 self.dropless.alloc(name_binding)
1048 fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> {
1049 self.imports.alloc(import)
1051 fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1052 self.name_resolutions.alloc(Default::default())
1054 fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> {
1055 PtrKey(self.dropless.alloc(Cell::new(scope)))
1057 fn alloc_macro_rules_binding(
1059 binding: MacroRulesBinding<'a>,
1060 ) -> &'a MacroRulesBinding<'a> {
1061 self.dropless.alloc(binding)
1063 fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] {
1064 self.ast_paths.alloc_from_iter(paths.iter().cloned())
1066 fn alloc_pattern_spans(&'a self, spans: impl Iterator<Item = Span>) -> &'a [Span] {
1067 self.dropless.alloc_from_iter(spans)
1071 impl<'a> AsMut<Resolver<'a>> for Resolver<'a> {
1072 fn as_mut(&mut self) -> &mut Resolver<'a> {
1077 impl<'a, 'b> DefIdTree for &'a Resolver<'b> {
1078 fn parent(self, id: DefId) -> Option<DefId> {
1079 match id.as_local() {
1080 Some(id) => self.definitions.def_key(id).parent,
1081 None => self.cstore().def_key(id).parent,
1083 .map(|index| DefId { index, ..id })
1087 /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that
1088 /// the resolver is no longer needed as all the relevant information is inline.
1089 impl ResolverAstLowering for Resolver<'_> {
1090 fn def_key(&mut self, id: DefId) -> DefKey {
1091 if let Some(id) = id.as_local() {
1092 self.definitions().def_key(id)
1094 self.cstore().def_key(id)
1098 fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize {
1099 self.cstore().item_generics_num_lifetimes(def_id, sess)
1102 fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
1103 self.legacy_const_generic_args(expr)
1106 fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
1107 self.partial_res_map.get(&id).cloned()
1110 fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> {
1111 self.import_res_map.get(&id).cloned().unwrap_or_default()
1114 fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> {
1115 self.label_res_map.get(&id).cloned()
1118 fn definitions(&mut self) -> &mut Definitions {
1119 &mut self.definitions
1122 fn lint_buffer(&mut self) -> &mut LintBuffer {
1123 &mut self.lint_buffer
1126 fn next_node_id(&mut self) -> NodeId {
1130 fn trait_map(&self) -> &NodeMap<Vec<TraitCandidate>> {
1134 fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
1135 self.node_id_to_def_id.get(&node).copied()
1138 fn local_def_id(&self, node: NodeId) -> LocalDefId {
1139 self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node))
1142 /// Adds a definition with a parent definition.
1146 node_id: ast::NodeId,
1152 !self.node_id_to_def_id.contains_key(&node_id),
1153 "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
1156 self.definitions.def_key(self.node_id_to_def_id[&node_id]),
1159 // Find the next free disambiguator for this key.
1160 let next_disambiguator = &mut self.next_disambiguator;
1161 let next_disambiguator = |parent, data| {
1162 let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0);
1163 let disambiguator = *next_disamb;
1164 *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
1168 let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator);
1170 assert_eq!(self.def_id_to_span.push(span), def_id);
1172 // Some things for which we allocate `LocalDefId`s don't correspond to
1173 // anything in the AST, so they don't have a `NodeId`. For these cases
1174 // we don't need a mapping from `NodeId` to `LocalDefId`.
1175 if node_id != ast::DUMMY_NODE_ID {
1176 debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
1177 self.node_id_to_def_id.insert(node_id, def_id);
1179 assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
1185 impl<'a> Resolver<'a> {
1187 session: &'a Session,
1190 metadata_loader: &'a MetadataLoaderDyn,
1191 arenas: &'a ResolverArenas<'a>,
1193 let root_local_def_id = LocalDefId { local_def_index: CRATE_DEF_INDEX };
1194 let root_def_id = root_local_def_id.to_def_id();
1195 let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1196 let graph_root = arenas.alloc_module(ModuleData {
1197 no_implicit_prelude: session.contains_name(&krate.attrs, sym::no_implicit_prelude),
1198 ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span)
1200 let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty);
1201 let empty_module = arenas.alloc_module(ModuleData {
1202 no_implicit_prelude: true,
1211 let mut module_map = FxHashMap::default();
1212 module_map.insert(root_local_def_id, graph_root);
1214 let definitions = Definitions::new(crate_name, session.local_crate_disambiguator());
1215 let root = definitions.get_root_def();
1217 let mut visibilities = FxHashMap::default();
1218 visibilities.insert(root_local_def_id, ty::Visibility::Public);
1220 let mut def_id_to_span = IndexVec::default();
1221 assert_eq!(def_id_to_span.push(rustc_span::DUMMY_SP), root);
1222 let mut def_id_to_node_id = IndexVec::default();
1223 assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root);
1224 let mut node_id_to_def_id = FxHashMap::default();
1225 node_id_to_def_id.insert(CRATE_NODE_ID, root);
1227 let mut invocation_parents = FxHashMap::default();
1228 invocation_parents.insert(ExpnId::root(), (root, ImplTraitContext::Existential));
1230 let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = session
1234 .filter(|(_, entry)| entry.add_prelude)
1235 .map(|(name, _)| (Ident::from_str(name), Default::default()))
1238 if !session.contains_name(&krate.attrs, sym::no_core) {
1239 extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default());
1240 if !session.contains_name(&krate.attrs, sym::no_std) {
1241 extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default());
1245 let (registered_attrs, registered_tools) =
1246 macros::registered_attrs_and_tools(session, &krate.attrs);
1248 let features = session.features_untracked();
1249 let non_macro_attr =
1250 |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition()));
1252 let mut resolver = Resolver {
1257 // The outermost module has def ID 0; this is not reflected in the
1263 has_self: FxHashSet::default(),
1264 field_names: FxHashMap::default(),
1266 determined_imports: Vec::new(),
1267 indeterminate_imports: Vec::new(),
1269 last_import_segment: false,
1270 unusable_binding: None,
1272 partial_res_map: Default::default(),
1273 import_res_map: Default::default(),
1274 label_res_map: Default::default(),
1275 extern_crate_map: Default::default(),
1276 export_map: FxHashMap::default(),
1277 trait_map: Default::default(),
1278 underscore_disambiguator: 0,
1281 block_map: Default::default(),
1282 extern_module_map: FxHashMap::default(),
1283 binding_parent_modules: FxHashMap::default(),
1284 ast_transform_scopes: FxHashMap::default(),
1286 glob_map: Default::default(),
1288 used_imports: FxHashSet::default(),
1289 maybe_unused_trait_imports: Default::default(),
1290 maybe_unused_extern_crates: Vec::new(),
1292 privacy_errors: Vec::new(),
1293 ambiguity_errors: Vec::new(),
1294 use_injections: Vec::new(),
1295 macro_expanded_macro_export_errors: BTreeSet::new(),
1298 dummy_binding: arenas.alloc_name_binding(NameBinding {
1299 kind: NameBindingKind::Res(Res::Err, false),
1301 expansion: ExpnId::root(),
1303 vis: ty::Visibility::Public,
1306 crate_loader: CrateLoader::new(session, metadata_loader, crate_name),
1307 macro_names: FxHashSet::default(),
1308 builtin_macros: Default::default(),
1311 macro_use_prelude: FxHashMap::default(),
1312 all_macros: FxHashMap::default(),
1313 macro_map: FxHashMap::default(),
1314 dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())),
1315 dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())),
1316 non_macro_attrs: [non_macro_attr(false), non_macro_attr(true)],
1317 invocation_parent_scopes: Default::default(),
1318 output_macro_rules_scopes: Default::default(),
1319 helper_attrs: Default::default(),
1320 derive_data: Default::default(),
1321 local_macro_def_scopes: FxHashMap::default(),
1322 name_already_seen: FxHashMap::default(),
1323 potentially_unused_imports: Vec::new(),
1324 struct_constructors: Default::default(),
1325 unused_macros: Default::default(),
1326 proc_macro_stubs: Default::default(),
1327 single_segment_macro_resolutions: Default::default(),
1328 multi_segment_macro_resolutions: Default::default(),
1329 builtin_attrs: Default::default(),
1330 containers_deriving_copy: Default::default(),
1331 active_features: features
1332 .declared_lib_features
1334 .map(|(feat, ..)| *feat)
1335 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
1337 lint_buffer: LintBuffer::default(),
1338 next_node_id: NodeId::from_u32(1),
1342 placeholder_field_indices: Default::default(),
1344 next_disambiguator: Default::default(),
1345 trait_impl_items: Default::default(),
1346 legacy_const_generic_args: Default::default(),
1349 let root_parent_scope = ParentScope::module(graph_root, &resolver);
1350 resolver.invocation_parent_scopes.insert(ExpnId::root(), root_parent_scope);
1355 pub fn next_node_id(&mut self) -> NodeId {
1360 .expect("input too large; ran out of NodeIds");
1361 self.next_node_id = ast::NodeId::from_usize(next);
1365 pub fn lint_buffer(&mut self) -> &mut LintBuffer {
1366 &mut self.lint_buffer
1369 pub fn arenas() -> ResolverArenas<'a> {
1373 pub fn into_outputs(self) -> ResolverOutputs {
1374 let definitions = self.definitions;
1375 let visibilities = self.visibilities;
1376 let extern_crate_map = self.extern_crate_map;
1377 let export_map = self.export_map;
1378 let maybe_unused_trait_imports = self.maybe_unused_trait_imports;
1379 let maybe_unused_extern_crates = self.maybe_unused_extern_crates;
1380 let glob_map = self.glob_map;
1383 cstore: Box::new(self.crate_loader.into_cstore()),
1388 maybe_unused_trait_imports,
1389 maybe_unused_extern_crates,
1390 extern_prelude: self
1393 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1398 pub fn clone_outputs(&self) -> ResolverOutputs {
1400 definitions: self.definitions.clone(),
1401 cstore: Box::new(self.cstore().clone()),
1402 visibilities: self.visibilities.clone(),
1403 extern_crate_map: self.extern_crate_map.clone(),
1404 export_map: self.export_map.clone(),
1405 glob_map: self.glob_map.clone(),
1406 maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(),
1407 maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(),
1408 extern_prelude: self
1411 .map(|(ident, entry)| (ident.name, entry.introduced_by_item))
1416 pub fn cstore(&self) -> &CStore {
1417 self.crate_loader.cstore()
1420 fn non_macro_attr(&self, mark_used: bool) -> Lrc<SyntaxExtension> {
1421 self.non_macro_attrs[mark_used as usize].clone()
1424 fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> {
1426 MacroKind::Bang => self.dummy_ext_bang.clone(),
1427 MacroKind::Derive => self.dummy_ext_derive.clone(),
1428 MacroKind::Attr => self.non_macro_attr(true),
1432 /// Runs the function on each namespace.
1433 fn per_ns<F: FnMut(&mut Self, Namespace)>(&mut self, mut f: F) {
1439 fn is_builtin_macro(&mut self, res: Res) -> bool {
1440 self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some())
1443 fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId {
1445 match ctxt.outer_expn_data().macro_def_id {
1446 Some(def_id) => return def_id,
1447 None => ctxt.remove_mark(),
1452 /// Entry point to crate resolution.
1453 pub fn resolve_crate(&mut self, krate: &Crate) {
1454 self.session.time("resolve_crate", || {
1455 self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports());
1456 self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions());
1457 self.session.time("late_resolve_crate", || self.late_resolve_crate(krate));
1458 self.session.time("resolve_check_unused", || self.check_unused(krate));
1459 self.session.time("resolve_report_errors", || self.report_errors(krate));
1460 self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate));
1464 pub fn traits_in_scope(
1466 current_trait: Option<Module<'a>>,
1467 parent_scope: &ParentScope<'a>,
1468 ctxt: SyntaxContext,
1469 assoc_item: Option<(Symbol, Namespace)>,
1470 ) -> Vec<TraitCandidate> {
1471 let mut found_traits = Vec::new();
1473 if let Some(module) = current_trait {
1474 if self.trait_may_have_item(Some(module), assoc_item) {
1475 let def_id = module.def_id().unwrap();
1476 found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] });
1480 self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| {
1482 Scope::Module(module, _) => {
1483 this.traits_in_module(module, assoc_item, &mut found_traits);
1485 Scope::StdLibPrelude => {
1486 if let Some(module) = this.prelude {
1487 this.traits_in_module(module, assoc_item, &mut found_traits);
1490 Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
1491 _ => unreachable!(),
1499 fn traits_in_module(
1502 assoc_item: Option<(Symbol, Namespace)>,
1503 found_traits: &mut Vec<TraitCandidate>,
1505 module.ensure_traits(self);
1506 let traits = module.traits.borrow();
1507 for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() {
1508 if self.trait_may_have_item(trait_binding.module(), assoc_item) {
1509 let def_id = trait_binding.res().def_id();
1510 let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name);
1511 found_traits.push(TraitCandidate { def_id, import_ids });
1516 // List of traits in scope is pruned on best effort basis. We reject traits not having an
1517 // associated item with the given name and namespace (if specified). This is a conservative
1518 // optimization, proper hygienic type-based resolution of associated items is done in typeck.
1519 // We don't reject trait aliases (`trait_module == None`) because we don't have access to their
1520 // associated items.
1521 fn trait_may_have_item(
1523 trait_module: Option<Module<'a>>,
1524 assoc_item: Option<(Symbol, Namespace)>,
1526 match (trait_module, assoc_item) {
1527 (Some(trait_module), Some((name, ns))) => {
1528 self.resolutions(trait_module).borrow().iter().any(|resolution| {
1529 let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
1530 assoc_ns == ns && assoc_ident.name == name
1537 fn find_transitive_imports(
1539 mut kind: &NameBindingKind<'_>,
1541 ) -> SmallVec<[LocalDefId; 1]> {
1542 let mut import_ids = smallvec![];
1543 while let NameBindingKind::Import { import, binding, .. } = kind {
1544 let id = self.local_def_id(import.id);
1545 self.maybe_unused_trait_imports.insert(id);
1546 self.add_to_glob_map(&import, trait_name);
1547 import_ids.push(id);
1548 kind = &binding.kind;
1557 nearest_parent_mod: DefId,
1561 let module = ModuleData::new(Some(parent), kind, nearest_parent_mod, expn_id, span);
1562 self.arenas.alloc_module(module)
1565 fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
1566 let ident = ident.normalize_to_macros_2_0();
1567 let disambiguator = if ident.name == kw::Underscore {
1568 self.underscore_disambiguator += 1;
1569 self.underscore_disambiguator
1573 BindingKey { ident, ns, disambiguator }
1576 fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> {
1577 if module.populate_on_access.get() {
1578 module.populate_on_access.set(false);
1579 self.build_reduced_graph_external(module);
1581 &module.lazy_resolutions
1588 ) -> &'a RefCell<NameResolution<'a>> {
1590 .resolutions(module)
1593 .or_insert_with(|| self.arenas.alloc_name_resolution())
1600 used_binding: &'a NameBinding<'a>,
1601 is_lexical_scope: bool,
1603 if let Some((b2, kind)) = used_binding.ambiguity {
1604 self.ambiguity_errors.push(AmbiguityError {
1609 misc1: AmbiguityErrorMisc::None,
1610 misc2: AmbiguityErrorMisc::None,
1613 if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind {
1614 // Avoid marking `extern crate` items that refer to a name from extern prelude,
1615 // but not introduce it, as used if they are accessed from lexical scope.
1616 if is_lexical_scope {
1617 if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) {
1618 if let Some(crate_item) = entry.extern_crate_item {
1619 if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item {
1626 import.used.set(true);
1627 self.used_imports.insert((import.id, ns));
1628 self.add_to_glob_map(&import, ident);
1629 self.record_use(ident, ns, binding, false);
1634 fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) {
1635 if import.is_glob() {
1636 let def_id = self.local_def_id(import.id);
1637 self.glob_map.entry(def_id).or_default().insert(ident.name);
1641 /// A generic scope visitor.
1642 /// Visits scopes in order to resolve some identifier in them or perform other actions.
1643 /// If the callback returns `Some` result, we stop visiting scopes and return it.
1646 scope_set: ScopeSet<'a>,
1647 parent_scope: &ParentScope<'a>,
1648 ctxt: SyntaxContext,
1649 mut visitor: impl FnMut(
1652 /*use_prelude*/ bool,
1656 // General principles:
1657 // 1. Not controlled (user-defined) names should have higher priority than controlled names
1658 // built into the language or standard library. This way we can add new names into the
1659 // language or standard library without breaking user code.
1660 // 2. "Closed set" below means new names cannot appear after the current resolution attempt.
1661 // Places to search (in order of decreasing priority):
1663 // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet
1664 // (open set, not controlled).
1665 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1666 // (open, not controlled).
1667 // 3. Extern prelude (open, the open part is from macro expansions, not controlled).
1668 // 4. Tool modules (closed, controlled right now, but not in the future).
1669 // 5. Standard library prelude (de-facto closed, controlled).
1670 // 6. Language prelude (closed, controlled).
1672 // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet
1673 // (open set, not controlled).
1674 // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1675 // (open, not controlled).
1676 // 3. Standard library prelude (de-facto closed, controlled).
1678 // 1-3. Derive helpers (open, not controlled). All ambiguities with other names
1679 // are currently reported as errors. They should be higher in priority than preludes
1680 // and probably even names in modules according to the "general principles" above. They
1681 // also should be subject to restricted shadowing because are effectively produced by
1682 // derives (you need to resolve the derive first to add helpers into scope), but they
1683 // should be available before the derive is expanded for compatibility.
1684 // It's mess in general, so we are being conservative for now.
1685 // 1-3. `macro_rules` (open, not controlled), loop through `macro_rules` scopes. Have higher
1686 // priority than prelude macros, but create ambiguities with macros in modules.
1687 // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents
1688 // (open, not controlled). Have higher priority than prelude macros, but create
1689 // ambiguities with `macro_rules`.
1690 // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled).
1691 // 4a. User-defined prelude from macro-use
1692 // (open, the open part is from macro expansions, not controlled).
1693 // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled).
1694 // 4c. Standard library prelude (de-facto closed, controlled).
1695 // 6. Language prelude: builtin attributes (closed, controlled).
1697 let rust_2015 = ctxt.edition() == Edition::Edition2015;
1698 let (ns, macro_kind, is_absolute_path) = match scope_set {
1699 ScopeSet::All(ns, _) => (ns, None, false),
1700 ScopeSet::AbsolutePath(ns) => (ns, None, true),
1701 ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false),
1702 ScopeSet::Late(ns, ..) => (ns, None, false),
1704 let module = match scope_set {
1705 // Start with the specified module.
1706 ScopeSet::Late(_, module, _) => module,
1707 // Jump out of trait or enum modules, they do not act as scopes.
1708 _ => parent_scope.module.nearest_item_scope(),
1710 let mut scope = match ns {
1711 _ if is_absolute_path => Scope::CrateRoot,
1712 TypeNS | ValueNS => Scope::Module(module, None),
1713 MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
1715 let mut ctxt = ctxt.normalize_to_macros_2_0();
1716 let mut use_prelude = !module.no_implicit_prelude;
1719 let visit = match scope {
1720 // Derive helpers are not in scope when resolving derives in the same container.
1721 Scope::DeriveHelpers(expn_id) => {
1722 !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive))
1724 Scope::DeriveHelpersCompat => true,
1725 Scope::MacroRules(macro_rules_scope) => {
1726 // Use "path compression" on `macro_rules` scope chains. This is an optimization
1727 // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`.
1728 // As another consequence of this optimization visitors never observe invocation
1729 // scopes for macros that were already expanded.
1730 while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() {
1731 if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) {
1732 macro_rules_scope.set(next_scope.get());
1739 Scope::CrateRoot => true,
1740 Scope::Module(..) => true,
1741 Scope::RegisteredAttrs => use_prelude,
1742 Scope::MacroUsePrelude => use_prelude || rust_2015,
1743 Scope::BuiltinAttrs => true,
1744 Scope::ExternPrelude => use_prelude || is_absolute_path,
1745 Scope::ToolPrelude => use_prelude,
1746 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
1747 Scope::BuiltinTypes => true,
1751 if let break_result @ Some(..) = visitor(self, scope, use_prelude, ctxt) {
1752 return break_result;
1756 scope = match scope {
1757 Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => {
1758 // Derive helpers are not visible to code generated by bang or derive macros.
1759 let expn_data = expn_id.expn_data();
1760 match expn_data.kind {
1762 | ExpnKind::Macro(MacroKind::Bang | MacroKind::Derive, _) => {
1763 Scope::DeriveHelpersCompat
1765 _ => Scope::DeriveHelpers(expn_data.parent),
1768 Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat,
1769 Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules),
1770 Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() {
1771 MacroRulesScope::Binding(binding) => {
1772 Scope::MacroRules(binding.parent_macro_rules_scope)
1774 MacroRulesScope::Invocation(invoc_id) => {
1775 Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules)
1777 MacroRulesScope::Empty => Scope::Module(module, None),
1779 Scope::CrateRoot => match ns {
1781 ctxt.adjust(ExpnId::root());
1782 Scope::ExternPrelude
1784 ValueNS | MacroNS => break,
1786 Scope::Module(module, prev_lint_id) => {
1787 use_prelude = !module.no_implicit_prelude;
1788 let derive_fallback_lint_id = match scope_set {
1789 ScopeSet::Late(.., lint_id) => lint_id,
1792 match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) {
1793 Some((parent_module, lint_id)) => {
1794 Scope::Module(parent_module, lint_id.or(prev_lint_id))
1797 ctxt.adjust(ExpnId::root());
1799 TypeNS => Scope::ExternPrelude,
1800 ValueNS => Scope::StdLibPrelude,
1801 MacroNS => Scope::RegisteredAttrs,
1806 Scope::RegisteredAttrs => Scope::MacroUsePrelude,
1807 Scope::MacroUsePrelude => Scope::StdLibPrelude,
1808 Scope::BuiltinAttrs => break, // nowhere else to search
1809 Scope::ExternPrelude if is_absolute_path => break,
1810 Scope::ExternPrelude => Scope::ToolPrelude,
1811 Scope::ToolPrelude => Scope::StdLibPrelude,
1812 Scope::StdLibPrelude => match ns {
1813 TypeNS => Scope::BuiltinTypes,
1814 ValueNS => break, // nowhere else to search
1815 MacroNS => Scope::BuiltinAttrs,
1817 Scope::BuiltinTypes => break, // nowhere else to search
1824 /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1825 /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1826 /// `ident` in the first scope that defines it (or None if no scopes define it).
1828 /// A block's items are above its local variables in the scope hierarchy, regardless of where
1829 /// the items are defined in the block. For example,
1832 /// g(); // Since there are no local variables in scope yet, this resolves to the item.
1835 /// g(); // This resolves to the local variable `g` since it shadows the item.
1839 /// Invariant: This must only be called during main resolution, not during
1840 /// import resolution.
1841 fn resolve_ident_in_lexical_scope(
1845 parent_scope: &ParentScope<'a>,
1846 record_used_id: Option<NodeId>,
1849 ) -> Option<LexicalScopeBinding<'a>> {
1850 assert!(ns == TypeNS || ns == ValueNS);
1851 let orig_ident = ident;
1852 if ident.name == kw::Empty {
1853 return Some(LexicalScopeBinding::Res(Res::Err));
1855 let (general_span, normalized_span) = if ident.name == kw::SelfUpper {
1856 // FIXME(jseyfried) improve `Self` hygiene
1857 let empty_span = ident.span.with_ctxt(SyntaxContext::root());
1858 (empty_span, empty_span)
1859 } else if ns == TypeNS {
1860 let normalized_span = ident.span.normalize_to_macros_2_0();
1861 (normalized_span, normalized_span)
1863 (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0())
1865 ident.span = general_span;
1866 let normalized_ident = Ident { span: normalized_span, ..ident };
1868 // Walk backwards up the ribs in scope.
1869 let record_used = record_used_id.is_some();
1870 let mut module = self.graph_root;
1871 for i in (0..ribs.len()).rev() {
1872 debug!("walk rib\n{:?}", ribs[i].bindings);
1873 // Use the rib kind to determine whether we are resolving parameters
1874 // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
1875 let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
1876 if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
1878 // The ident resolves to a type parameter or local variable.
1879 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
1885 *original_rib_ident_def,
1890 module = match ribs[i].kind {
1891 ModuleRibKind(module) => module,
1892 MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
1893 // If an invocation of this macro created `ident`, give up on `ident`
1894 // and switch to `ident`'s source from the macro definition.
1895 ident.span.remove_mark();
1902 ModuleKind::Block(..) => {} // We can see through blocks
1906 let item = self.resolve_ident_in_module_unadjusted(
1907 ModuleOrUniformRoot::Module(module),
1914 if let Ok(binding) = item {
1915 // The ident resolves to an item.
1916 return Some(LexicalScopeBinding::Item(binding));
1920 self.early_resolve_ident_in_lexical_scope(
1922 ScopeSet::Late(ns, module, record_used_id),
1929 .map(LexicalScopeBinding::Item)
1932 fn hygienic_lexical_parent(
1935 ctxt: &mut SyntaxContext,
1936 derive_fallback_lint_id: Option<NodeId>,
1937 ) -> Option<(Module<'a>, Option<NodeId>)> {
1938 if !module.expansion.outer_expn_is_descendant_of(*ctxt) {
1939 return Some((self.macro_def_scope(ctxt.remove_mark()), None));
1942 if let ModuleKind::Block(..) = module.kind {
1943 return Some((module.parent.unwrap().nearest_item_scope(), None));
1946 // We need to support the next case under a deprecation warning
1949 // ---- begin: this comes from a proc macro derive
1950 // mod implementation_details {
1951 // // Note that `MyStruct` is not in scope here.
1952 // impl SomeTrait for MyStruct { ... }
1956 // So we have to fall back to the module's parent during lexical resolution in this case.
1957 if derive_fallback_lint_id.is_some() {
1958 if let Some(parent) = module.parent {
1959 // Inner module is inside the macro, parent module is outside of the macro.
1960 if module.expansion != parent.expansion
1961 && module.expansion.is_descendant_of(parent.expansion)
1963 // The macro is a proc macro derive
1964 if let Some(def_id) = module.expansion.expn_data().macro_def_id {
1965 let ext = self.get_macro_by_def_id(def_id);
1966 if ext.builtin_name.is_none()
1967 && ext.macro_kind() == MacroKind::Derive
1968 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
1970 return Some((parent, derive_fallback_lint_id));
1980 fn resolve_ident_in_module(
1982 module: ModuleOrUniformRoot<'a>,
1985 parent_scope: &ParentScope<'a>,
1988 ) -> Result<&'a NameBinding<'a>, Determinacy> {
1989 self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span)
1990 .map_err(|(determinacy, _)| determinacy)
1993 fn resolve_ident_in_module_ext(
1995 module: ModuleOrUniformRoot<'a>,
1998 parent_scope: &ParentScope<'a>,
2001 ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> {
2002 let tmp_parent_scope;
2003 let mut adjusted_parent_scope = parent_scope;
2005 ModuleOrUniformRoot::Module(m) => {
2006 if let Some(def) = ident.span.normalize_to_macros_2_0_and_adjust(m.expansion) {
2008 ParentScope { module: self.macro_def_scope(def), ..*parent_scope };
2009 adjusted_parent_scope = &tmp_parent_scope;
2012 ModuleOrUniformRoot::ExternPrelude => {
2013 ident.span.normalize_to_macros_2_0_and_adjust(ExpnId::root());
2015 ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => {
2019 self.resolve_ident_in_module_unadjusted_ext(
2023 adjusted_parent_scope,
2030 fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> {
2031 debug!("resolve_crate_root({:?})", ident);
2032 let mut ctxt = ident.span.ctxt();
2033 let mark = if ident.name == kw::DollarCrate {
2034 // When resolving `$crate` from a `macro_rules!` invoked in a `macro`,
2035 // we don't want to pretend that the `macro_rules!` definition is in the `macro`
2036 // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks.
2037 // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!`
2038 // definitions actually produced by `macro` and `macro` definitions produced by
2039 // `macro_rules!`, but at least such configurations are not stable yet.
2040 ctxt = ctxt.normalize_to_macro_rules();
2042 "resolve_crate_root: marks={:?}",
2043 ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::<Vec<_>>()
2045 let mut iter = ctxt.marks().into_iter().rev().peekable();
2046 let mut result = None;
2047 // Find the last opaque mark from the end if it exists.
2048 while let Some(&(mark, transparency)) = iter.peek() {
2049 if transparency == Transparency::Opaque {
2050 result = Some(mark);
2057 "resolve_crate_root: found opaque mark {:?} {:?}",
2059 result.map(|r| r.expn_data())
2061 // Then find the last semi-transparent mark from the end if it exists.
2062 for (mark, transparency) in iter {
2063 if transparency == Transparency::SemiTransparent {
2064 result = Some(mark);
2070 "resolve_crate_root: found semi-transparent mark {:?} {:?}",
2072 result.map(|r| r.expn_data())
2076 debug!("resolve_crate_root: not DollarCrate");
2077 ctxt = ctxt.normalize_to_macros_2_0();
2078 ctxt.adjust(ExpnId::root())
2080 let module = match mark {
2081 Some(def) => self.macro_def_scope(def),
2084 "resolve_crate_root({:?}): found no mark (ident.span = {:?})",
2087 return self.graph_root;
2090 let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.nearest_parent_mod });
2092 "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
2101 fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
2102 let mut module = self.get_module(module.nearest_parent_mod);
2103 while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
2104 let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
2105 module = self.get_module(parent.nearest_parent_mod);
2113 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2114 parent_scope: &ParentScope<'a>,
2117 crate_lint: CrateLint,
2118 ) -> PathResult<'a> {
2119 self.resolve_path_with_ribs(
2130 fn resolve_path_with_ribs(
2133 opt_ns: Option<Namespace>, // `None` indicates a module path in import
2134 parent_scope: &ParentScope<'a>,
2137 crate_lint: CrateLint,
2138 ribs: Option<&PerNS<Vec<Rib<'a>>>>,
2139 ) -> PathResult<'a> {
2140 let mut module = None;
2141 let mut allow_super = true;
2142 let mut second_binding = None;
2145 "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \
2146 path_span={:?}, crate_lint={:?})",
2147 path, opt_ns, record_used, path_span, crate_lint,
2150 for (i, &Segment { ident, id, has_generic_args: _ }) in path.iter().enumerate() {
2151 debug!("resolve_path ident {} {:?} {:?}", i, ident, id);
2152 let record_segment_res = |this: &mut Self, res| {
2154 if let Some(id) = id {
2155 if !this.partial_res_map.contains_key(&id) {
2156 assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id");
2157 this.record_partial_res(id, PartialRes::new(res));
2163 let is_last = i == path.len() - 1;
2164 let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2165 let name = ident.name;
2167 allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super);
2170 if allow_super && name == kw::Super {
2171 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2172 let self_module = match i {
2173 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)),
2175 Some(ModuleOrUniformRoot::Module(module)) => Some(module),
2179 if let Some(self_module) = self_module {
2180 if let Some(parent) = self_module.parent {
2181 module = Some(ModuleOrUniformRoot::Module(
2182 self.resolve_self(&mut ctxt, parent),
2187 let msg = "there are too many leading `super` keywords".to_string();
2188 return PathResult::Failed {
2192 is_error_from_last_segment: false,
2196 if name == kw::SelfLower {
2197 let mut ctxt = ident.span.ctxt().normalize_to_macros_2_0();
2198 module = Some(ModuleOrUniformRoot::Module(
2199 self.resolve_self(&mut ctxt, parent_scope.module),
2203 if name == kw::PathRoot && ident.span.rust_2018() {
2204 module = Some(ModuleOrUniformRoot::ExternPrelude);
2207 if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() {
2208 // `::a::b` from 2015 macro on 2018 global edition
2209 module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude);
2212 if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate {
2213 // `::a::b`, `crate::a::b` or `$crate::a::b`
2214 module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident)));
2220 // Report special messages for path segment keywords in wrong positions.
2221 if ident.is_path_segment_keyword() && i != 0 {
2222 let name_str = if name == kw::PathRoot {
2223 "crate root".to_string()
2225 format!("`{}`", name)
2227 let label = if i == 1 && path[0].ident.name == kw::PathRoot {
2228 format!("global paths cannot start with {}", name_str)
2230 format!("{} in paths can only be used in start position", name_str)
2232 return PathResult::Failed {
2236 is_error_from_last_segment: false,
2240 enum FindBindingResult<'a> {
2241 Binding(Result<&'a NameBinding<'a>, Determinacy>),
2242 PathResult(PathResult<'a>),
2244 let find_binding_in_ns = |this: &mut Self, ns| {
2245 let binding = if let Some(module) = module {
2246 this.resolve_ident_in_module(
2254 } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) {
2255 let scopes = ScopeSet::All(ns, opt_ns.is_none());
2256 this.early_resolve_ident_in_lexical_scope(
2265 let record_used_id = if record_used {
2266 crate_lint.node_id().or(Some(CRATE_NODE_ID))
2270 match this.resolve_ident_in_lexical_scope(
2278 // we found a locally-imported or available item/module
2279 Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2280 // we found a local variable or type param
2281 Some(LexicalScopeBinding::Res(res))
2282 if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) =>
2284 record_segment_res(this, res);
2285 return FindBindingResult::PathResult(PathResult::NonModule(
2286 PartialRes::with_unresolved_segments(res, path.len() - 1),
2289 _ => Err(Determinacy::determined(record_used)),
2292 FindBindingResult::Binding(binding)
2294 let binding = match find_binding_in_ns(self, ns) {
2295 FindBindingResult::PathResult(x) => return x,
2296 FindBindingResult::Binding(binding) => binding,
2301 second_binding = Some(binding);
2303 let res = binding.res();
2304 let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res);
2305 if let Some(next_module) = binding.module() {
2306 module = Some(ModuleOrUniformRoot::Module(next_module));
2307 record_segment_res(self, res);
2308 } else if res == Res::ToolMod && i + 1 != path.len() {
2309 if binding.is_import() {
2313 "cannot use a tool module through an import",
2315 .span_note(binding.span, "the tool module imported here")
2318 let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
2319 return PathResult::NonModule(PartialRes::new(res));
2320 } else if res == Res::Err {
2321 return PathResult::NonModule(PartialRes::new(Res::Err));
2322 } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2323 self.lint_if_path_starts_with_module(
2329 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2334 let label = format!(
2335 "`{}` is {} {}, not a module",
2341 return PathResult::Failed {
2345 is_error_from_last_segment: is_last,
2349 Err(Undetermined) => return PathResult::Indeterminate,
2350 Err(Determined) => {
2351 if let Some(ModuleOrUniformRoot::Module(module)) = module {
2352 if opt_ns.is_some() && !module.is_normal() {
2353 return PathResult::NonModule(PartialRes::with_unresolved_segments(
2354 module.res().unwrap(),
2359 let module_res = match module {
2360 Some(ModuleOrUniformRoot::Module(module)) => module.res(),
2363 let (label, suggestion) = if module_res == self.graph_root.res() {
2364 let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
2365 // Don't look up import candidates if this is a speculative resolve
2366 let mut candidates = if record_used {
2367 self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod)
2371 candidates.sort_by_cached_key(|c| {
2372 (c.path.segments.len(), pprust::path_to_string(&c.path))
2374 if let Some(candidate) = candidates.get(0) {
2376 String::from("unresolved import"),
2378 vec![(ident.span, pprust::path_to_string(&candidate.path))],
2379 String::from("a similar path exists"),
2380 Applicability::MaybeIncorrect,
2383 } else if self.session.edition() == Edition::Edition2015 {
2384 (format!("maybe a missing crate `{}`?", ident), None)
2386 (format!("could not find `{}` in the crate root", ident), None)
2394 .map_or(false, |c| c.is_ascii_uppercase())
2396 (format!("use of undeclared type `{}`", ident), None)
2398 (format!("use of undeclared crate or module `{}`", ident), None)
2401 let parent = path[i - 1].ident.name;
2402 let parent = match parent {
2403 // ::foo is mounted at the crate root for 2015, and is the extern
2404 // prelude for 2018+
2405 kw::PathRoot if self.session.edition() > Edition::Edition2015 => {
2406 "the list of imported crates".to_owned()
2408 kw::PathRoot | kw::Crate => "the crate root".to_owned(),
2410 format!("`{}`", parent)
2414 let mut msg = format!("could not find `{}` in {}", ident, parent);
2415 if ns == TypeNS || ns == ValueNS {
2416 let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
2417 if let FindBindingResult::Binding(Ok(binding)) =
2418 find_binding_in_ns(self, ns_to_try)
2420 let mut found = |what| {
2422 "expected {}, found {} `{}` in {}",
2429 if binding.module().is_some() {
2432 match binding.res() {
2433 def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)),
2434 _ => found(ns_to_try.descr()),
2441 return PathResult::Failed {
2445 is_error_from_last_segment: is_last,
2451 self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding);
2453 PathResult::Module(match module {
2454 Some(module) => module,
2455 None if path.is_empty() => ModuleOrUniformRoot::CurrentScope,
2456 _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path),
2460 fn lint_if_path_starts_with_module(
2462 crate_lint: CrateLint,
2465 second_binding: Option<&NameBinding<'_>>,
2467 let (diag_id, diag_span) = match crate_lint {
2468 CrateLint::No => return,
2469 CrateLint::SimplePath(id) => (id, path_span),
2470 CrateLint::UsePath { root_id, root_span } => (root_id, root_span),
2471 CrateLint::QPathTrait { qpath_id, qpath_span } => (qpath_id, qpath_span),
2474 let first_name = match path.get(0) {
2475 // In the 2018 edition this lint is a hard error, so nothing to do
2476 Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name,
2480 // We're only interested in `use` paths which should start with
2481 // `{{root}}` currently.
2482 if first_name != kw::PathRoot {
2487 // If this import looks like `crate::...` it's already good
2488 Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
2489 // Otherwise go below to see if it's an extern crate
2491 // If the path has length one (and it's `PathRoot` most likely)
2492 // then we don't know whether we're gonna be importing a crate or an
2493 // item in our crate. Defer this lint to elsewhere
2497 // If the first element of our path was actually resolved to an
2498 // `ExternCrate` (also used for `crate::...`) then no need to issue a
2499 // warning, this looks all good!
2500 if let Some(binding) = second_binding {
2501 if let NameBindingKind::Import { import, .. } = binding.kind {
2502 // Careful: we still want to rewrite paths from renamed extern crates.
2503 if let ImportKind::ExternCrate { source: None, .. } = import.kind {
2509 let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span);
2510 self.lint_buffer.buffer_lint_with_diagnostic(
2511 lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
2514 "absolute paths must start with `self`, `super`, \
2515 `crate`, or an external crate name in the 2018 edition",
2520 // Validate a local resolution (from ribs).
2521 fn validate_res_from_ribs(
2528 original_rib_ident_def: Ident,
2529 all_ribs: &[Rib<'a>],
2531 const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation";
2532 debug!("validate_res_from_ribs({:?})", res);
2533 let ribs = &all_ribs[rib_index + 1..];
2535 // An invalid forward use of a generic parameter from a previous default.
2536 if let ForwardGenericParamBanRibKind = all_ribs[rib_index].kind {
2538 let res_error = if rib_ident.name == kw::SelfUpper {
2539 ResolutionError::SelfInTyParamDefault
2541 ResolutionError::ForwardDeclaredTyParam
2543 self.report_error(span, res_error);
2545 assert_eq!(res, Res::Err);
2551 use ResolutionError::*;
2552 let mut res_err = None;
2557 | ClosureOrAsyncRibKind
2559 | MacroDefinition(..)
2560 | ForwardGenericParamBanRibKind => {
2561 // Nothing to do. Continue.
2563 ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => {
2564 // This was an attempt to access an upvar inside a
2565 // named function item. This is not allowed, so we
2568 // We don't immediately trigger a resolve error, because
2569 // we want certain other resolution errors (namely those
2570 // emitted for `ConstantItemRibKind` below) to take
2572 res_err = Some(CannotCaptureDynamicEnvironmentInFnItem);
2575 ConstantItemRibKind(_, item) => {
2576 // Still doesn't deal with upvars
2578 let (span, resolution_error) =
2579 if let Some((ident, constant_item_kind)) = item {
2580 let kind_str = match constant_item_kind {
2581 ConstantItemKind::Const => "const",
2582 ConstantItemKind::Static => "static",
2586 AttemptToUseNonConstantValueInConstant(
2587 ident, "let", kind_str,
2593 AttemptToUseNonConstantValueInConstant(
2594 original_rib_ident_def,
2600 self.report_error(span, resolution_error);
2604 ConstParamTyRibKind => {
2606 self.report_error(span, ParamInTyOfConstParam(rib_ident.name));
2612 if let Some(res_err) = res_err {
2613 self.report_error(span, res_err);
2617 Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => {
2618 let mut in_ty_param_default = false;
2620 let has_generic_params = match rib.kind {
2622 | ClosureOrAsyncRibKind
2625 | MacroDefinition(..) => {
2626 // Nothing to do. Continue.
2630 // We only forbid constant items if we are inside of type defaults,
2631 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2632 ForwardGenericParamBanRibKind => {
2633 // FIXME(const_generic_defaults): we may need to distinguish between
2634 // being in type parameter defaults and const parameter defaults
2635 in_ty_param_default = true;
2638 ConstantItemRibKind(trivial, _) => {
2639 let features = self.session.features_untracked();
2640 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2642 || features.const_generics
2643 || features.lazy_normalization_consts)
2645 // HACK(min_const_generics): If we encounter `Self` in an anonymous constant
2646 // we can't easily tell if it's generic at this stage, so we instead remember
2647 // this and then enforce the self type to be concrete later on.
2648 if let Res::SelfTy(trait_def, Some((impl_def, _))) = res {
2649 res = Res::SelfTy(trait_def, Some((impl_def, true)));
2654 ResolutionError::ParamInNonTrivialAnonConst {
2655 name: rib_ident.name,
2661 self.session.delay_span_bug(span, CG_BUG_STR);
2666 if in_ty_param_default {
2670 ResolutionError::ParamInAnonConstInTyDefault(
2681 // This was an attempt to use a type parameter outside its scope.
2682 ItemRibKind(has_generic_params) => has_generic_params,
2683 FnItemRibKind => HasGenericParams::Yes,
2684 ConstParamTyRibKind => {
2688 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2698 ResolutionError::GenericParamsFromOuterFunction(
2707 Res::Def(DefKind::ConstParam, _) => {
2708 let mut ribs = ribs.iter().peekable();
2709 if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() {
2710 // When declaring const parameters inside function signatures, the first rib
2711 // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it
2712 // (spuriously) conflicting with the const param.
2716 let mut in_ty_param_default = false;
2718 let has_generic_params = match rib.kind {
2720 | ClosureOrAsyncRibKind
2723 | MacroDefinition(..) => continue,
2725 // We only forbid constant items if we are inside of type defaults,
2726 // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>`
2727 ForwardGenericParamBanRibKind => {
2728 // FIXME(const_generic_defaults): we may need to distinguish between
2729 // being in type parameter defaults and const parameter defaults
2730 in_ty_param_default = true;
2733 ConstantItemRibKind(trivial, _) => {
2734 let features = self.session.features_untracked();
2735 // HACK(min_const_generics): We currently only allow `N` or `{ N }`.
2737 || features.const_generics
2738 || features.lazy_normalization_consts)
2743 ResolutionError::ParamInNonTrivialAnonConst {
2744 name: rib_ident.name,
2750 self.session.delay_span_bug(span, CG_BUG_STR);
2754 if in_ty_param_default {
2758 ResolutionError::ParamInAnonConstInTyDefault(
2769 ItemRibKind(has_generic_params) => has_generic_params,
2770 FnItemRibKind => HasGenericParams::Yes,
2771 ConstParamTyRibKind => {
2775 ResolutionError::ParamInTyOfConstParam(rib_ident.name),
2782 // This was an attempt to use a const parameter outside its scope.
2786 ResolutionError::GenericParamsFromOuterFunction(
2800 fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) {
2801 debug!("(recording res) recording {:?} for {}", resolution, node_id);
2802 if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) {
2803 panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
2807 fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
2808 vis.is_accessible_from(module.nearest_parent_mod, self)
2811 fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) {
2812 if let Some(old_module) = self.binding_parent_modules.insert(PtrKey(binding), module) {
2813 if !ptr::eq(module, old_module) {
2814 span_bug!(binding.span, "parent module is reset for binding");
2819 fn disambiguate_macro_rules_vs_modularized(
2821 macro_rules: &'a NameBinding<'a>,
2822 modularized: &'a NameBinding<'a>,
2824 // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules"
2825 // is disambiguated to mitigate regressions from macro modularization.
2826 // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
2828 self.binding_parent_modules.get(&PtrKey(macro_rules)),
2829 self.binding_parent_modules.get(&PtrKey(modularized)),
2831 (Some(macro_rules), Some(modularized)) => {
2832 macro_rules.nearest_parent_mod == modularized.nearest_parent_mod
2833 && modularized.is_ancestor_of(macro_rules)
2839 fn report_errors(&mut self, krate: &Crate) {
2840 self.report_with_use_injections(krate);
2842 for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
2843 let msg = "macro-expanded `macro_export` macros from the current crate \
2844 cannot be referred to by absolute paths";
2845 self.lint_buffer.buffer_lint_with_diagnostic(
2846 lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
2850 BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
2854 for ambiguity_error in &self.ambiguity_errors {
2855 self.report_ambiguity_error(ambiguity_error);
2858 let mut reported_spans = FxHashSet::default();
2859 for error in &self.privacy_errors {
2860 if reported_spans.insert(error.dedup_span) {
2861 self.report_privacy_error(error);
2866 fn report_with_use_injections(&mut self, krate: &Crate) {
2867 for UseError { mut err, candidates, def_id, instead, suggestion } in
2868 self.use_injections.drain(..)
2870 let (span, found_use) = if let Some(def_id) = def_id.as_local() {
2871 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
2875 if !candidates.is_empty() {
2876 diagnostics::show_candidates(&mut err, span, &candidates, instead, found_use);
2877 } else if let Some((span, msg, sugg, appl)) = suggestion {
2878 err.span_suggestion(span, msg, sugg, appl);
2884 fn report_conflict<'b>(
2889 new_binding: &NameBinding<'b>,
2890 old_binding: &NameBinding<'b>,
2892 // Error on the second of two conflicting names
2893 if old_binding.span.lo() > new_binding.span.lo() {
2894 return self.report_conflict(parent, ident, ns, old_binding, new_binding);
2897 let container = match parent.kind {
2898 ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id().unwrap()),
2899 ModuleKind::Block(..) => "block",
2902 let old_noun = match old_binding.is_import() {
2904 false => "definition",
2907 let new_participle = match new_binding.is_import() {
2913 (ident.name, self.session.source_map().guess_head_span(new_binding.span));
2915 if let Some(s) = self.name_already_seen.get(&name) {
2921 let old_kind = match (ns, old_binding.module()) {
2922 (ValueNS, _) => "value",
2923 (MacroNS, _) => "macro",
2924 (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
2925 (TypeNS, Some(module)) if module.is_normal() => "module",
2926 (TypeNS, Some(module)) if module.is_trait() => "trait",
2927 (TypeNS, _) => "type",
2930 let msg = format!("the name `{}` is defined multiple times", name);
2932 let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
2933 (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
2934 (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
2935 true => struct_span_err!(self.session, span, E0254, "{}", msg),
2936 false => struct_span_err!(self.session, span, E0260, "{}", msg),
2938 _ => match (old_binding.is_import(), new_binding.is_import()) {
2939 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
2940 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
2941 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
2946 "`{}` must be defined only once in the {} namespace of this {}",
2952 err.span_label(span, format!("`{}` re{} here", name, new_participle));
2954 self.session.source_map().guess_head_span(old_binding.span),
2955 format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
2958 // See https://github.com/rust-lang/rust/issues/32354
2959 use NameBindingKind::Import;
2960 let import = match (&new_binding.kind, &old_binding.kind) {
2961 // If there are two imports where one or both have attributes then prefer removing the
2962 // import without attributes.
2963 (Import { import: new, .. }, Import { import: old, .. })
2965 !new_binding.span.is_dummy()
2966 && !old_binding.span.is_dummy()
2967 && (new.has_attributes || old.has_attributes)
2970 if old.has_attributes {
2971 Some((new, new_binding.span, true))
2973 Some((old, old_binding.span, true))
2976 // Otherwise prioritize the new binding.
2977 (Import { import, .. }, other) if !new_binding.span.is_dummy() => {
2978 Some((import, new_binding.span, other.is_import()))
2980 (other, Import { import, .. }) if !old_binding.span.is_dummy() => {
2981 Some((import, old_binding.span, other.is_import()))
2986 // Check if the target of the use for both bindings is the same.
2987 let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
2988 let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
2990 self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
2991 // Only suggest removing an import if both bindings are to the same def, if both spans
2992 // aren't dummy spans. Further, if both bindings are imports, then the ident must have
2993 // been introduced by a item.
2994 let should_remove_import = duplicate
2996 && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
2999 Some((import, span, true)) if should_remove_import && import.is_nested() => {
3000 self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
3002 Some((import, _, true)) if should_remove_import && !import.is_glob() => {
3003 // Simple case - remove the entire import. Due to the above match arm, this can
3004 // only be a single use so just remove it entirely.
3005 err.tool_only_span_suggestion(
3006 import.use_span_with_attributes,
3007 "remove unnecessary import",
3009 Applicability::MaybeIncorrect,
3012 Some((import, span, _)) => {
3013 self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
3019 self.name_already_seen.insert(name, span);
3022 /// This function adds a suggestion to change the binding name of a new import that conflicts
3023 /// with an existing import.
3025 /// ```text,ignore (diagnostic)
3026 /// help: you can use `as` to change the binding name of the import
3028 /// LL | use foo::bar as other_bar;
3029 /// | ^^^^^^^^^^^^^^^^^^^^^
3031 fn add_suggestion_for_rename_of_use(
3033 err: &mut DiagnosticBuilder<'_>,
3035 import: &Import<'_>,
3038 let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
3039 format!("Other{}", name)
3041 format!("other_{}", name)
3044 let mut suggestion = None;
3046 ImportKind::Single { type_ns_only: true, .. } => {
3047 suggestion = Some(format!("self as {}", suggested_name))
3049 ImportKind::Single { source, .. } => {
3051 source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
3053 if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) {
3054 if pos <= snippet.len() {
3055 suggestion = Some(format!(
3059 if snippet.ends_with(';') { ";" } else { "" }
3065 ImportKind::ExternCrate { source, target, .. } => {
3066 suggestion = Some(format!(
3067 "extern crate {} as {};",
3068 source.unwrap_or(target.name),
3072 _ => unreachable!(),
3075 let rename_msg = "you can use `as` to change the binding name of the import";
3076 if let Some(suggestion) = suggestion {
3077 err.span_suggestion(
3081 Applicability::MaybeIncorrect,
3084 err.span_label(binding_span, rename_msg);
3088 /// This function adds a suggestion to remove a unnecessary binding from an import that is
3089 /// nested. In the following example, this function will be invoked to remove the `a` binding
3090 /// in the second use statement:
3092 /// ```ignore (diagnostic)
3093 /// use issue_52891::a;
3094 /// use issue_52891::{d, a, e};
3097 /// The following suggestion will be added:
3099 /// ```ignore (diagnostic)
3100 /// use issue_52891::{d, a, e};
3101 /// ^-- help: remove unnecessary import
3104 /// If the nested use contains only one import then the suggestion will remove the entire
3107 /// It is expected that the provided import is nested - this isn't checked by the
3108 /// function. If this invariant is not upheld, this function's behaviour will be unexpected
3109 /// as characters expected by span manipulations won't be present.
3110 fn add_suggestion_for_duplicate_nested_use(
3112 err: &mut DiagnosticBuilder<'_>,
3113 import: &Import<'_>,
3116 assert!(import.is_nested());
3117 let message = "remove unnecessary import";
3119 // Two examples will be used to illustrate the span manipulations we're doing:
3121 // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
3122 // `a` and `import.use_span` is `issue_52891::{d, a, e};`.
3123 // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
3124 // `a` and `import.use_span` is `issue_52891::{d, e, a};`.
3126 let (found_closing_brace, span) =
3127 find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span);
3129 // If there was a closing brace then identify the span to remove any trailing commas from
3130 // previous imports.
3131 if found_closing_brace {
3132 if let Some(span) = extend_span_to_previous_binding(self.session, span) {
3133 err.tool_only_span_suggestion(
3137 Applicability::MaybeIncorrect,
3140 // Remove the entire line if we cannot extend the span back, this indicates a
3141 // `issue_52891::{self}` case.
3142 err.span_suggestion(
3143 import.use_span_with_attributes,
3146 Applicability::MaybeIncorrect,
3153 err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable);
3156 fn extern_prelude_get(
3160 ) -> Option<&'a NameBinding<'a>> {
3161 if ident.is_path_segment_keyword() {
3162 // Make sure `self`, `super` etc produce an error when passed to here.
3165 self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
3166 if let Some(binding) = entry.extern_crate_item {
3167 if !speculative && entry.introduced_by_item {
3168 self.record_use(ident, TypeNS, binding, false);
3172 let crate_id = if !speculative {
3173 self.crate_loader.process_path_extern(ident.name, ident.span)
3175 self.crate_loader.maybe_process_path_extern(ident.name)?
3177 let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
3179 (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root())
3180 .to_name_binding(self.arenas),
3186 /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'a>`
3187 /// isn't something that can be returned because it can't be made to live that long,
3188 /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
3189 /// just that an error occurred.
3190 // FIXME(Manishearth): intra-doc links won't get warned of epoch changes.
3191 pub fn resolve_str_path_error(
3197 ) -> Result<(ast::Path, Res), ()> {
3198 let path = if path_str.starts_with("::") {
3201 segments: iter::once(Ident::with_dummy_span(kw::PathRoot))
3202 .chain(path_str.split("::").skip(1).map(Ident::from_str))
3203 .map(|i| self.new_ast_path_segment(i))
3212 .map(Ident::from_str)
3213 .map(|i| self.new_ast_path_segment(i))
3218 let module = self.get_module(module_id);
3219 let parent_scope = &ParentScope::module(module, self);
3220 let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
3224 // Resolve a path passed from rustdoc or HIR lowering.
3225 fn resolve_ast_path(
3229 parent_scope: &ParentScope<'a>,
3230 ) -> Result<Res, (Span, ResolutionError<'a>)> {
3231 match self.resolve_path(
3232 &Segment::from_path(path),
3239 PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()),
3240 PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => {
3241 Ok(path_res.base_res())
3243 PathResult::NonModule(..) => Err((
3245 ResolutionError::FailedToResolve {
3246 label: String::from("type-relative paths are not supported in this context"),
3250 PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),
3251 PathResult::Failed { span, label, suggestion, .. } => {
3252 Err((span, ResolutionError::FailedToResolve { label, suggestion }))
3257 fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment {
3258 let mut seg = ast::PathSegment::from_ident(ident);
3259 seg.id = self.next_node_id();
3264 pub fn graph_root(&self) -> Module<'a> {
3269 pub fn all_macros(&self) -> &FxHashMap<Symbol, Res> {
3273 /// Retrieves the span of the given `DefId` if `DefId` is in the local crate.
3275 pub fn opt_span(&self, def_id: DefId) -> Option<Span> {
3276 if let Some(def_id) = def_id.as_local() { Some(self.def_id_to_span[def_id]) } else { None }
3279 /// Checks if an expression refers to a function marked with
3280 /// `#[rustc_legacy_const_generics]` and returns the argument index list
3281 /// from the attribute.
3282 pub fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>> {
3283 if let ExprKind::Path(None, path) = &expr.kind {
3284 // Don't perform legacy const generics rewriting if the path already
3285 // has generic arguments.
3286 if path.segments.last().unwrap().args.is_some() {
3290 let partial_res = self.partial_res_map.get(&expr.id)?;
3291 if partial_res.unresolved_segments() != 0 {
3295 if let Res::Def(def::DefKind::Fn, def_id) = partial_res.base_res() {
3296 // We only support cross-crate argument rewriting. Uses
3297 // within the same crate should be updated to use the new
3298 // const generics style.
3299 if def_id.is_local() {
3303 if let Some(v) = self.legacy_const_generic_args.get(&def_id) {
3307 let parse_attrs = || {
3308 let attrs = self.cstore().item_attrs(def_id, self.session);
3311 .find(|a| self.session.check_name(a, sym::rustc_legacy_const_generics))?;
3312 let mut ret = vec![];
3313 for meta in attr.meta_item_list()? {
3314 match meta.literal()?.kind {
3315 LitKind::Int(a, _) => {
3316 ret.push(a as usize);
3318 _ => panic!("invalid arg index"),
3324 // Cache the lookup to avoid parsing attributes for an iterm
3326 let ret = parse_attrs();
3327 self.legacy_const_generic_args.insert(def_id, ret.clone());
3335 fn names_to_string(names: &[Symbol]) -> String {
3336 let mut result = String::new();
3337 for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() {
3339 result.push_str("::");
3341 if Ident::with_dummy_span(*name).is_raw_guess() {
3342 result.push_str("r#");
3344 result.push_str(&name.as_str());
3349 fn path_names_to_string(path: &Path) -> String {
3350 names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>())
3353 /// A somewhat inefficient routine to obtain the name of a module.
3354 fn module_to_string(module: Module<'_>) -> Option<String> {
3355 let mut names = Vec::new();
3357 fn collect_mod(names: &mut Vec<Symbol>, module: Module<'_>) {
3358 if let ModuleKind::Def(.., name) = module.kind {
3359 if let Some(parent) = module.parent {
3361 collect_mod(names, parent);
3364 names.push(Symbol::intern("<opaque>"));
3365 collect_mod(names, module.parent.unwrap());
3368 collect_mod(&mut names, module);
3370 if names.is_empty() {
3374 Some(names_to_string(&names))
3377 #[derive(Copy, Clone, Debug)]
3379 /// Do not issue the lint.
3382 /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`.
3383 /// In this case, we can take the span of that path.
3386 /// This lint comes from a `use` statement. In this case, what we
3387 /// care about really is the *root* `use` statement; e.g., if we
3388 /// have nested things like `use a::{b, c}`, we care about the
3390 UsePath { root_id: NodeId, root_span: Span },
3392 /// This is the "trait item" from a fully qualified path. For example,
3393 /// we might be resolving `X::Y::Z` from a path like `<T as X::Y>::Z`.
3394 /// The `path_span` is the span of the to the trait itself (`X::Y`).
3395 QPathTrait { qpath_id: NodeId, qpath_span: Span },
3399 fn node_id(&self) -> Option<NodeId> {
3401 CrateLint::No => None,
3402 CrateLint::SimplePath(id)
3403 | CrateLint::UsePath { root_id: id, .. }
3404 | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id),
3409 pub fn provide(providers: &mut Providers) {
3410 late::lifetimes::provide(providers);