// ignore-tidy-filelength //! This crate is responsible for the part of name resolution that doesn't require type checker. //! //! Module structure of the crate is built here. //! Paths in macros, imports, expressions, types, patterns are resolved here. //! Label and lifetime names are resolved here as well. //! //! Type-relative name resolution (methods, fields, associated items) happens in `rustc_typeck`. #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")] #![feature(box_patterns)] #![feature(drain_filter)] #![feature(bool_to_option)] #![feature(crate_visibility_modifier)] #![feature(let_chains)] #![feature(let_else)] #![feature(never_type)] #![feature(nll)] #![recursion_limit = "256"] #![allow(rustdoc::private_intra_doc_links)] #![allow(rustc::potential_query_instability)] #[macro_use] extern crate tracing; pub use rustc_hir::def::{Namespace, PerNS}; use rustc_arena::{DroplessArena, TypedArena}; use rustc_ast::node_id::NodeMap; use rustc_ast::ptr::P; use rustc_ast::visit::{self, Visitor}; use rustc_ast::{self as ast, NodeId}; use rustc_ast::{Crate, CRATE_NODE_ID}; use rustc_ast::{Expr, ExprKind, LitKind}; use rustc_ast::{ItemKind, ModKind, Path}; use rustc_ast_lowering::ResolverAstLowering; use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap}; use rustc_data_structures::intern::Interned; use rustc_data_structures::sync::Lrc; use rustc_errors::{ struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, }; use rustc_expand::base::{DeriveResolutions, SyntaxExtension, SyntaxExtensionKind}; use rustc_hir::def::Namespace::*; use rustc_hir::def::{self, CtorOf, DefKind, PartialRes}; use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefPathHash, LocalDefId}; use rustc_hir::def_id::{CRATE_DEF_ID, CRATE_DEF_INDEX, LOCAL_CRATE}; use rustc_hir::definitions::{DefKey, DefPathData, Definitions}; use rustc_hir::TraitCandidate; use rustc_index::vec::IndexVec; use rustc_metadata::creader::{CStore, CrateLoader}; use rustc_middle::metadata::ModChild; use rustc_middle::middle::privacy::AccessLevels; use rustc_middle::span_bug; use rustc_middle::ty::query::Providers; use rustc_middle::ty::{self, DefIdTree, MainDefinition, RegisteredTools, ResolverOutputs}; use rustc_query_system::ich::StableHashingContext; use rustc_session::cstore::{CrateStore, MetadataLoaderDyn}; use rustc_session::lint; use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer}; use rustc_session::Session; use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind, SyntaxContext, Transparency}; use rustc_span::source_map::Spanned; use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::{Span, DUMMY_SP}; use smallvec::{smallvec, SmallVec}; use std::cell::{Cell, RefCell}; use std::collections::BTreeSet; use std::{cmp, fmt, mem, ptr}; use tracing::debug; use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding}; use diagnostics::{ImportSuggestion, LabelSuggestion, Suggestion}; use imports::{Import, ImportKind, ImportResolver, NameResolution}; use late::{HasGenericParams, PathSource}; use macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef}; use crate::access_levels::AccessLevelsVisitor; type Res = def::Res; mod access_levels; mod build_reduced_graph; mod check_unused; mod def_collector; mod diagnostics; mod ident; mod imports; mod late; mod macros; enum Weak { Yes, No, } #[derive(Copy, Clone, PartialEq, Debug)] pub enum Determinacy { Determined, Undetermined, } impl Determinacy { fn determined(determined: bool) -> Determinacy { if determined { Determinacy::Determined } else { Determinacy::Undetermined } } } /// A specific scope in which a name can be looked up. /// This enum is currently used only for early resolution (imports and macros), /// but not for late resolution yet. #[derive(Clone, Copy)] enum Scope<'a> { DeriveHelpers(LocalExpnId), DeriveHelpersCompat, MacroRules(MacroRulesScopeRef<'a>), CrateRoot, // The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK` // lint if it should be reported. Module(Module<'a>, Option), RegisteredAttrs, MacroUsePrelude, BuiltinAttrs, ExternPrelude, ToolPrelude, StdLibPrelude, BuiltinTypes, } /// Names from different contexts may want to visit different subsets of all specific scopes /// with different restrictions when looking up the resolution. /// This enum is currently used only for early resolution (imports and macros), /// but not for late resolution yet. #[derive(Clone, Copy)] enum ScopeSet<'a> { /// All scopes with the given namespace. All(Namespace, /*is_import*/ bool), /// Crate root, then extern prelude (used for mixed 2015-2018 mode in macros). AbsolutePath(Namespace), /// All scopes with macro namespace and the given macro kind restriction. Macro(MacroKind), /// All scopes with the given namespace, used for partially performing late resolution. /// The node id enables lints and is used for reporting them. Late(Namespace, Module<'a>, Option), } /// Everything you need to know about a name's location to resolve it. /// Serves as a starting point for the scope visitor. /// This struct is currently used only for early resolution (imports and macros), /// but not for late resolution yet. #[derive(Clone, Copy, Debug)] pub struct ParentScope<'a> { module: Module<'a>, expansion: LocalExpnId, macro_rules: MacroRulesScopeRef<'a>, derives: &'a [ast::Path], } impl<'a> ParentScope<'a> { /// Creates a parent scope with the passed argument used as the module scope component, /// and other scope components set to default empty values. pub fn module(module: Module<'a>, resolver: &Resolver<'a>) -> ParentScope<'a> { ParentScope { module, expansion: LocalExpnId::ROOT, macro_rules: resolver.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty), derives: &[], } } } #[derive(Copy, Debug, Clone)] enum ImplTraitContext { Existential, Universal(LocalDefId), } #[derive(Eq)] struct BindingError { name: Symbol, origin: BTreeSet, target: BTreeSet, could_be_path: bool, } impl PartialOrd for BindingError { fn partial_cmp(&self, other: &BindingError) -> Option { Some(self.cmp(other)) } } impl PartialEq for BindingError { fn eq(&self, other: &BindingError) -> bool { self.name == other.name } } impl Ord for BindingError { fn cmp(&self, other: &BindingError) -> cmp::Ordering { self.name.cmp(&other.name) } } enum ResolutionError<'a> { /// Error E0401: can't use type or const parameters from outer function. GenericParamsFromOuterFunction(Res, HasGenericParams), /// Error E0403: the name is already used for a type or const parameter in this generic /// parameter list. NameAlreadyUsedInParameterList(Symbol, Span), /// Error E0407: method is not a member of trait. MethodNotMemberOfTrait(Ident, &'a str, Option), /// Error E0437: type is not a member of trait. TypeNotMemberOfTrait(Ident, &'a str, Option), /// Error E0438: const is not a member of trait. ConstNotMemberOfTrait(Ident, &'a str, Option), /// Error E0408: variable `{}` is not bound in all patterns. VariableNotBoundInPattern(&'a BindingError), /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm. VariableBoundWithDifferentMode(Symbol, Span), /// Error E0415: identifier is bound more than once in this parameter list. IdentifierBoundMoreThanOnceInParameterList(Symbol), /// Error E0416: identifier is bound more than once in the same pattern. IdentifierBoundMoreThanOnceInSamePattern(Symbol), /// Error E0426: use of undeclared label. UndeclaredLabel { name: Symbol, suggestion: Option }, /// Error E0429: `self` imports are only allowed within a `{ }` list. SelfImportsOnlyAllowedWithin { root: bool, span_with_rename: Span }, /// Error E0430: `self` import can only appear once in the list. SelfImportCanOnlyAppearOnceInTheList, /// Error E0431: `self` import can only appear in an import list with a non-empty prefix. SelfImportOnlyInImportListWithNonEmptyPrefix, /// Error E0433: failed to resolve. FailedToResolve { label: String, suggestion: Option }, /// Error E0434: can't capture dynamic environment in a fn item. CannotCaptureDynamicEnvironmentInFnItem, /// Error E0435: attempt to use a non-constant value in a constant. AttemptToUseNonConstantValueInConstant( Ident, /* suggestion */ &'static str, /* current */ &'static str, ), /// Error E0530: `X` bindings cannot shadow `Y`s. BindingShadowsSomethingUnacceptable { shadowing_binding_descr: &'static str, name: Symbol, participle: &'static str, article: &'static str, shadowed_binding_descr: &'static str, shadowed_binding_span: Span, }, /// Error E0128: generic parameters with a default cannot use forward-declared identifiers. ForwardDeclaredGenericParam, /// ERROR E0770: the type of const parameters must not depend on other generic parameters. ParamInTyOfConstParam(Symbol), /// generic parameters must not be used inside const evaluations. /// /// This error is only emitted when using `min_const_generics`. ParamInNonTrivialAnonConst { name: Symbol, is_type: bool }, /// Error E0735: generic parameters with a default cannot use `Self` SelfInGenericParamDefault, /// Error E0767: use of unreachable label UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option }, /// Error E0323, E0324, E0325: mismatch between trait item and impl item. TraitImplMismatch { name: Symbol, kind: &'static str, trait_path: String, trait_item_span: Span, code: rustc_errors::DiagnosticId, }, } enum VisResolutionError<'a> { Relative2018(Span, &'a ast::Path), AncestorOnly(Span), FailedToResolve(Span, String, Option), ExpectedFound(Span, String, Res), Indeterminate(Span), ModuleOnly(Span), } /// A minimal representation of a path segment. We use this in resolve because we synthesize 'path /// segments' which don't have the rest of an AST or HIR `PathSegment`. #[derive(Clone, Copy, Debug)] pub struct Segment { ident: Ident, id: Option, /// Signals whether this `PathSegment` has generic arguments. Used to avoid providing /// nonsensical suggestions. has_generic_args: bool, } impl Segment { fn from_path(path: &Path) -> Vec { path.segments.iter().map(|s| s.into()).collect() } fn from_ident(ident: Ident) -> Segment { Segment { ident, id: None, has_generic_args: false } } fn names_to_string(segments: &[Segment]) -> String { names_to_string(&segments.iter().map(|seg| seg.ident.name).collect::>()) } } impl<'a> From<&'a ast::PathSegment> for Segment { fn from(seg: &'a ast::PathSegment) -> Segment { Segment { ident: seg.ident, id: Some(seg.id), has_generic_args: seg.args.is_some() } } } #[derive(Debug)] struct UsePlacementFinder { target_module: NodeId, first_legal_span: Option, first_use_span: Option, } impl UsePlacementFinder { fn check(krate: &Crate, target_module: NodeId) -> (Option, bool) { let mut finder = UsePlacementFinder { target_module, first_legal_span: None, first_use_span: None }; finder.visit_crate(krate); if let Some(use_span) = finder.first_use_span { (Some(use_span), true) } else { (finder.first_legal_span, false) } } } fn is_span_suitable_for_use_injection(s: Span) -> bool { // don't suggest placing a use before the prelude // import or other generated ones !s.from_expansion() } fn search_for_any_use_in_items(items: &[P]) -> Option { for item in items { if let ItemKind::Use(..) = item.kind { if is_span_suitable_for_use_injection(item.span) { return Some(item.span.shrink_to_lo()); } } } return None; } impl<'tcx> Visitor<'tcx> for UsePlacementFinder { fn visit_crate(&mut self, c: &Crate) { if self.target_module == CRATE_NODE_ID { let inject = c.spans.inject_use_span; if is_span_suitable_for_use_injection(inject) { self.first_legal_span = Some(inject); } self.first_use_span = search_for_any_use_in_items(&c.items); return; } else { visit::walk_crate(self, c); } } fn visit_item(&mut self, item: &'tcx ast::Item) { if self.target_module == item.id { if let ItemKind::Mod(_, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind { let inject = mod_spans.inject_use_span; if is_span_suitable_for_use_injection(inject) { self.first_legal_span = Some(inject); } self.first_use_span = search_for_any_use_in_items(items); return; } } else { visit::walk_item(self, item); } } } /// An intermediate resolution result. /// /// This refers to the thing referred by a name. The difference between `Res` and `Item` is that /// items are visible in their whole block, while `Res`es only from the place they are defined /// forward. #[derive(Debug)] enum LexicalScopeBinding<'a> { Item(&'a NameBinding<'a>), Res(Res), } impl<'a> LexicalScopeBinding<'a> { fn res(self) -> Res { match self { LexicalScopeBinding::Item(binding) => binding.res(), LexicalScopeBinding::Res(res) => res, } } } #[derive(Copy, Clone, Debug)] enum ModuleOrUniformRoot<'a> { /// Regular module. Module(Module<'a>), /// Virtual module that denotes resolution in crate root with fallback to extern prelude. CrateRootAndExternPrelude, /// Virtual module that denotes resolution in extern prelude. /// Used for paths starting with `::` on 2018 edition. ExternPrelude, /// Virtual module that denotes resolution in current scope. /// Used only for resolving single-segment imports. The reason it exists is that import paths /// are always split into two parts, the first of which should be some kind of module. CurrentScope, } impl ModuleOrUniformRoot<'_> { fn same_def(lhs: Self, rhs: Self) -> bool { match (lhs, rhs) { (ModuleOrUniformRoot::Module(lhs), ModuleOrUniformRoot::Module(rhs)) => { ptr::eq(lhs, rhs) } ( ModuleOrUniformRoot::CrateRootAndExternPrelude, ModuleOrUniformRoot::CrateRootAndExternPrelude, ) | (ModuleOrUniformRoot::ExternPrelude, ModuleOrUniformRoot::ExternPrelude) | (ModuleOrUniformRoot::CurrentScope, ModuleOrUniformRoot::CurrentScope) => true, _ => false, } } } #[derive(Clone, Debug)] enum PathResult<'a> { Module(ModuleOrUniformRoot<'a>), NonModule(PartialRes), Indeterminate, Failed { span: Span, label: String, suggestion: Option, is_error_from_last_segment: bool, }, } impl<'a> PathResult<'a> { fn failed( span: Span, is_error_from_last_segment: bool, finalize: bool, label_and_suggestion: impl FnOnce() -> (String, Option), ) -> PathResult<'a> { let (label, suggestion) = if finalize { label_and_suggestion() } else { (String::new(), None) }; PathResult::Failed { span, label, suggestion, is_error_from_last_segment } } } #[derive(Debug)] enum ModuleKind { /// An anonymous module; e.g., just a block. /// /// ``` /// fn main() { /// fn f() {} // (1) /// { // This is an anonymous module /// f(); // This resolves to (2) as we are inside the block. /// fn f() {} // (2) /// } /// f(); // Resolves to (1) /// } /// ``` Block(NodeId), /// Any module with a name. /// /// This could be: /// /// * A normal module – either `mod from_file;` or `mod from_block { }` – /// or the crate root (which is conceptually a top-level module). /// Note that the crate root's [name][Self::name] will be [`kw::Empty`]. /// * A trait or an enum (it implicitly contains associated types, methods and variant /// constructors). Def(DefKind, DefId, Symbol), } impl ModuleKind { /// Get name of the module. pub fn name(&self) -> Option { match self { ModuleKind::Block(..) => None, ModuleKind::Def(.., name) => Some(*name), } } } /// A key that identifies a binding in a given `Module`. /// /// Multiple bindings in the same module can have the same key (in a valid /// program) if all but one of them come from glob imports. #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] struct BindingKey { /// The identifier for the binding, always the `normalize_to_macros_2_0` version of the /// identifier. ident: Ident, ns: Namespace, /// 0 if ident is not `_`, otherwise a value that's unique to the specific /// `_` in the expanded AST that introduced this binding. disambiguator: u32, } type Resolutions<'a> = RefCell>>>; /// One node in the tree of modules. /// /// Note that a "module" in resolve is broader than a `mod` that you declare in Rust code. It may be one of these: /// /// * `mod` /// * crate root (aka, top-level anonymous module) /// * `enum` /// * `trait` /// * curly-braced block with statements /// /// You can use [`ModuleData::kind`] to determine the kind of module this is. pub struct ModuleData<'a> { /// The direct parent module (it may not be a `mod`, however). parent: Option>, /// What kind of module this is, because this may not be a `mod`. kind: ModuleKind, /// Mapping between names and their (possibly in-progress) resolutions in this module. /// Resolutions in modules from other crates are not populated until accessed. lazy_resolutions: Resolutions<'a>, /// True if this is a module from other crate that needs to be populated on access. populate_on_access: Cell, /// Macro invocations that can expand into items in this module. unexpanded_invocations: RefCell>, /// Whether `#[no_implicit_prelude]` is active. no_implicit_prelude: bool, glob_importers: RefCell>>, globs: RefCell>>, /// Used to memoize the traits in this module for faster searches through all traits in scope. traits: RefCell)]>>>, /// Span of the module itself. Used for error reporting. span: Span, expansion: ExpnId, } type Module<'a> = &'a ModuleData<'a>; impl<'a> ModuleData<'a> { fn new( parent: Option>, kind: ModuleKind, expansion: ExpnId, span: Span, no_implicit_prelude: bool, ) -> Self { let is_foreign = match kind { ModuleKind::Def(_, def_id, _) => !def_id.is_local(), ModuleKind::Block(_) => false, }; ModuleData { parent, kind, lazy_resolutions: Default::default(), populate_on_access: Cell::new(is_foreign), unexpanded_invocations: Default::default(), no_implicit_prelude, glob_importers: RefCell::new(Vec::new()), globs: RefCell::new(Vec::new()), traits: RefCell::new(None), span, expansion, } } fn for_each_child(&'a self, resolver: &mut R, mut f: F) where R: AsMut>, F: FnMut(&mut R, Ident, Namespace, &'a NameBinding<'a>), { for (key, name_resolution) in resolver.as_mut().resolutions(self).borrow().iter() { if let Some(binding) = name_resolution.borrow().binding { f(resolver, key.ident, key.ns, binding); } } } /// This modifies `self` in place. The traits will be stored in `self.traits`. fn ensure_traits(&'a self, resolver: &mut R) where R: AsMut>, { let mut traits = self.traits.borrow_mut(); if traits.is_none() { let mut collected_traits = Vec::new(); self.for_each_child(resolver, |_, name, ns, binding| { if ns != TypeNS { return; } if let Res::Def(DefKind::Trait | DefKind::TraitAlias, _) = binding.res() { collected_traits.push((name, binding)) } }); *traits = Some(collected_traits.into_boxed_slice()); } } fn res(&self) -> Option { match self.kind { ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)), _ => None, } } // Public for rustdoc. pub fn def_id(&self) -> DefId { self.opt_def_id().expect("`ModuleData::def_id` is called on a block module") } fn opt_def_id(&self) -> Option { match self.kind { ModuleKind::Def(_, def_id, _) => Some(def_id), _ => None, } } // `self` resolves to the first module ancestor that `is_normal`. fn is_normal(&self) -> bool { matches!(self.kind, ModuleKind::Def(DefKind::Mod, _, _)) } fn is_trait(&self) -> bool { matches!(self.kind, ModuleKind::Def(DefKind::Trait, _, _)) } fn nearest_item_scope(&'a self) -> Module<'a> { match self.kind { ModuleKind::Def(DefKind::Enum | DefKind::Trait, ..) => { self.parent.expect("enum or trait module without a parent") } _ => self, } } /// The [`DefId`] of the nearest `mod` item ancestor (which may be this module). /// This may be the crate root. fn nearest_parent_mod(&self) -> DefId { match self.kind { ModuleKind::Def(DefKind::Mod, def_id, _) => def_id, _ => self.parent.expect("non-root module without parent").nearest_parent_mod(), } } fn is_ancestor_of(&self, mut other: &Self) -> bool { while !ptr::eq(self, other) { if let Some(parent) = other.parent { other = parent; } else { return false; } } true } } impl<'a> fmt::Debug for ModuleData<'a> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "{:?}", self.res()) } } /// Records a possibly-private value, type, or module definition. #[derive(Clone, Debug)] pub struct NameBinding<'a> { kind: NameBindingKind<'a>, ambiguity: Option<(&'a NameBinding<'a>, AmbiguityKind)>, expansion: LocalExpnId, span: Span, vis: ty::Visibility, } pub trait ToNameBinding<'a> { fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>; } impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> { fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> { self } } #[derive(Clone, Debug)] enum NameBindingKind<'a> { Res(Res, /* is_macro_export */ bool), Module(Module<'a>), Import { binding: &'a NameBinding<'a>, import: &'a Import<'a>, used: Cell }, } impl<'a> NameBindingKind<'a> { /// Is this a name binding of an import? fn is_import(&self) -> bool { matches!(*self, NameBindingKind::Import { .. }) } } struct PrivacyError<'a> { ident: Ident, binding: &'a NameBinding<'a>, dedup_span: Span, } struct UseError<'a> { err: DiagnosticBuilder<'a, ErrorGuaranteed>, /// Candidates which user could `use` to access the missing type. candidates: Vec, /// The `DefId` of the module to place the use-statements in. def_id: DefId, /// Whether the diagnostic should say "instead" (as in `consider importing ... instead`). instead: bool, /// Extra free-form suggestion. suggestion: Option<(Span, &'static str, String, Applicability)>, } #[derive(Clone, Copy, PartialEq, Debug)] enum AmbiguityKind { Import, BuiltinAttr, DeriveHelper, MacroRulesVsModularized, GlobVsOuter, GlobVsGlob, GlobVsExpanded, MoreExpandedVsOuter, } impl AmbiguityKind { fn descr(self) -> &'static str { match self { AmbiguityKind::Import => "multiple potential import sources", AmbiguityKind::BuiltinAttr => "a name conflict with a builtin attribute", AmbiguityKind::DeriveHelper => "a name conflict with a derive helper attribute", AmbiguityKind::MacroRulesVsModularized => { "a conflict between a `macro_rules` name and a non-`macro_rules` name from another module" } AmbiguityKind::GlobVsOuter => { "a conflict between a name from a glob import and an outer scope during import or macro resolution" } AmbiguityKind::GlobVsGlob => "multiple glob imports of a name in the same module", AmbiguityKind::GlobVsExpanded => { "a conflict between a name from a glob import and a macro-expanded name in the same module during import or macro resolution" } AmbiguityKind::MoreExpandedVsOuter => { "a conflict between a macro-expanded name and a less macro-expanded name from outer scope during import or macro resolution" } } } } /// Miscellaneous bits of metadata for better ambiguity error reporting. #[derive(Clone, Copy, PartialEq)] enum AmbiguityErrorMisc { SuggestCrate, SuggestSelf, FromPrelude, None, } struct AmbiguityError<'a> { kind: AmbiguityKind, ident: Ident, b1: &'a NameBinding<'a>, b2: &'a NameBinding<'a>, misc1: AmbiguityErrorMisc, misc2: AmbiguityErrorMisc, } impl<'a> NameBinding<'a> { fn module(&self) -> Option> { match self.kind { NameBindingKind::Module(module) => Some(module), NameBindingKind::Import { binding, .. } => binding.module(), _ => None, } } fn res(&self) -> Res { match self.kind { NameBindingKind::Res(res, _) => res, NameBindingKind::Module(module) => module.res().unwrap(), NameBindingKind::Import { binding, .. } => binding.res(), } } fn is_ambiguity(&self) -> bool { self.ambiguity.is_some() || match self.kind { NameBindingKind::Import { binding, .. } => binding.is_ambiguity(), _ => false, } } fn is_possibly_imported_variant(&self) -> bool { match self.kind { NameBindingKind::Import { binding, .. } => binding.is_possibly_imported_variant(), NameBindingKind::Res( Res::Def(DefKind::Variant | DefKind::Ctor(CtorOf::Variant, ..), _), _, ) => true, NameBindingKind::Res(..) | NameBindingKind::Module(..) => false, } } fn is_extern_crate(&self) -> bool { match self.kind { NameBindingKind::Import { import: &Import { kind: ImportKind::ExternCrate { .. }, .. }, .. } => true, NameBindingKind::Module(&ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }) => def_id.index == CRATE_DEF_INDEX, _ => false, } } fn is_import(&self) -> bool { matches!(self.kind, NameBindingKind::Import { .. }) } fn is_glob_import(&self) -> bool { match self.kind { NameBindingKind::Import { import, .. } => import.is_glob(), _ => false, } } fn is_importable(&self) -> bool { !matches!( self.res(), Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _) ) } fn macro_kind(&self) -> Option { self.res().macro_kind() } // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding` // at some expansion round `max(invoc, binding)` when they both emerged from macros. // Then this function returns `true` if `self` may emerge from a macro *after* that // in some later round and screw up our previously found resolution. // See more detailed explanation in // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049 fn may_appear_after( &self, invoc_parent_expansion: LocalExpnId, binding: &NameBinding<'_>, ) -> bool { // self > max(invoc, binding) => !(self <= invoc || self <= binding) // Expansions are partially ordered, so "may appear after" is an inversion of // "certainly appears before or simultaneously" and includes unordered cases. let self_parent_expansion = self.expansion; let other_parent_expansion = binding.expansion; let certainly_before_other_or_simultaneously = other_parent_expansion.is_descendant_of(self_parent_expansion); let certainly_before_invoc_or_simultaneously = invoc_parent_expansion.is_descendant_of(self_parent_expansion); !(certainly_before_other_or_simultaneously || certainly_before_invoc_or_simultaneously) } } #[derive(Debug, Default, Clone)] pub struct ExternPreludeEntry<'a> { extern_crate_item: Option<&'a NameBinding<'a>>, pub introduced_by_item: bool, } /// Used for better errors for E0773 enum BuiltinMacroState { NotYetSeen(SyntaxExtensionKind), AlreadySeen(Span), } struct DeriveData { resolutions: DeriveResolutions, helper_attrs: Vec<(usize, Ident)>, has_derive_copy: bool, } /// The main resolver class. /// /// This is the visitor that walks the whole crate. pub struct Resolver<'a> { session: &'a Session, definitions: Definitions, graph_root: Module<'a>, prelude: Option>, extern_prelude: FxHashMap>, /// N.B., this is used only for better diagnostics, not name resolution itself. has_self: FxHashSet, /// Names of fields of an item `DefId` accessible with dot syntax. /// Used for hints during error reporting. field_names: FxHashMap>>, /// All imports known to succeed or fail. determined_imports: Vec<&'a Import<'a>>, /// All non-determined imports. indeterminate_imports: Vec<&'a Import<'a>>, // Spans for local variables found during pattern resolution. // Used for suggestions during error reporting. pat_span_map: NodeMap, /// Resolutions for nodes that have a single resolution. partial_res_map: NodeMap, /// Resolutions for import nodes, which have multiple resolutions in different namespaces. import_res_map: NodeMap>>, /// Resolutions for labels (node IDs of their corresponding blocks or loops). label_res_map: NodeMap, /// `CrateNum` resolutions of `extern crate` items. extern_crate_map: FxHashMap, reexport_map: FxHashMap>, trait_map: NodeMap>, /// A map from nodes to anonymous modules. /// Anonymous modules are pseudo-modules that are implicitly created around items /// contained within blocks. /// /// For example, if we have this: /// /// fn f() { /// fn g() { /// ... /// } /// } /// /// There will be an anonymous module created around `g` with the ID of the /// entry block for `f`. block_map: NodeMap>, /// A fake module that contains no definition and no prelude. Used so that /// some AST passes can generate identifiers that only resolve to local or /// language items. empty_module: Module<'a>, module_map: FxHashMap>, binding_parent_modules: FxHashMap>, Module<'a>>, underscore_disambiguator: u32, /// Maps glob imports to the names of items actually imported. glob_map: FxHashMap>, /// Visibilities in "lowered" form, for all entities that have them. visibilities: FxHashMap, used_imports: FxHashSet, maybe_unused_trait_imports: FxHashSet, maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, /// Privacy errors are delayed until the end in order to deduplicate them. privacy_errors: Vec>, /// Ambiguity errors are delayed for deduplication. ambiguity_errors: Vec>, /// `use` injections are delayed for better placement and deduplication. use_injections: Vec>, /// Crate-local macro expanded `macro_export` referred to by a module-relative path. macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>, arenas: &'a ResolverArenas<'a>, dummy_binding: &'a NameBinding<'a>, crate_loader: CrateLoader<'a>, macro_names: FxHashSet, builtin_macros: FxHashMap, /// A small map keeping true kinds of built-in macros that appear to be fn-like on /// the surface (`macro` items in libcore), but are actually attributes or derives. builtin_macro_kinds: FxHashMap, registered_attrs: FxHashSet, registered_tools: RegisteredTools, macro_use_prelude: FxHashMap>, /// FIXME: The only user of this is a doc link resolution hack for rustdoc. all_macro_rules: FxHashMap, macro_map: FxHashMap>, dummy_ext_bang: Lrc, dummy_ext_derive: Lrc, non_macro_attr: Lrc, local_macro_def_scopes: FxHashMap>, ast_transform_scopes: FxHashMap>, unused_macros: FxHashMap, proc_macro_stubs: FxHashSet, /// Traces collected during macro resolution and validated when it's complete. single_segment_macro_resolutions: Vec<(Ident, MacroKind, ParentScope<'a>, Option<&'a NameBinding<'a>>)>, multi_segment_macro_resolutions: Vec<(Vec, Span, MacroKind, ParentScope<'a>, Option)>, builtin_attrs: Vec<(Ident, ParentScope<'a>)>, /// `derive(Copy)` marks items they are applied to so they are treated specially later. /// Derive macros cannot modify the item themselves and have to store the markers in the global /// context, so they attach the markers to derive container IDs using this resolver table. containers_deriving_copy: FxHashSet, /// Parent scopes in which the macros were invoked. /// FIXME: `derives` are missing in these parent scopes and need to be taken from elsewhere. invocation_parent_scopes: FxHashMap>, /// `macro_rules` scopes *produced* by expanding the macro invocations, /// include all the `macro_rules` items and other invocations generated by them. output_macro_rules_scopes: FxHashMap>, /// Helper attributes that are in scope for the given expansion. helper_attrs: FxHashMap>, /// Ready or in-progress results of resolving paths inside the `#[derive(...)]` attribute /// with the given `ExpnId`. derive_data: FxHashMap, /// Avoid duplicated errors for "name already defined". name_already_seen: FxHashMap, potentially_unused_imports: Vec<&'a Import<'a>>, /// Table for mapping struct IDs into struct constructor IDs, /// it's not used during normal resolution, only for better error reporting. /// Also includes of list of each fields visibility struct_constructors: DefIdMap<(Res, ty::Visibility, Vec)>, /// Features enabled for this crate. active_features: FxHashSet, lint_buffer: LintBuffer, next_node_id: NodeId, node_id_to_def_id: FxHashMap, def_id_to_node_id: IndexVec, /// Indices of unnamed struct or variant fields with unresolved attributes. placeholder_field_indices: FxHashMap, /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId` /// we know what parent node that fragment should be attached to thanks to this table, /// and how the `impl Trait` fragments were introduced. invocation_parents: FxHashMap, /// Some way to know that we are in a *trait* impl in `visit_assoc_item`. /// FIXME: Replace with a more general AST map (together with some other fields). trait_impl_items: FxHashSet, legacy_const_generic_args: FxHashMap>>, /// Amount of lifetime parameters for each item in the crate. item_generics_num_lifetimes: FxHashMap, main_def: Option, trait_impls: FxIndexMap>, /// A list of proc macro LocalDefIds, written out in the order in which /// they are declared in the static array generated by proc_macro_harness. proc_macros: Vec, confused_type_with_std_module: FxHashMap, access_levels: AccessLevels, } /// Nothing really interesting here; it just provides memory for the rest of the crate. #[derive(Default)] pub struct ResolverArenas<'a> { modules: TypedArena>, local_modules: RefCell>>, imports: TypedArena>, name_resolutions: TypedArena>>, ast_paths: TypedArena, dropless: DroplessArena, } impl<'a> ResolverArenas<'a> { fn new_module( &'a self, parent: Option>, kind: ModuleKind, expn_id: ExpnId, span: Span, no_implicit_prelude: bool, module_map: &mut FxHashMap>, ) -> Module<'a> { let module = self.modules.alloc(ModuleData::new(parent, kind, expn_id, span, no_implicit_prelude)); let def_id = module.opt_def_id(); if def_id.map_or(true, |def_id| def_id.is_local()) { self.local_modules.borrow_mut().push(module); } if let Some(def_id) = def_id { module_map.insert(def_id, module); } module } fn local_modules(&'a self) -> std::cell::Ref<'a, Vec>> { self.local_modules.borrow() } fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> { self.dropless.alloc(name_binding) } fn alloc_import(&'a self, import: Import<'a>) -> &'a Import<'_> { self.imports.alloc(import) } fn alloc_name_resolution(&'a self) -> &'a RefCell> { self.name_resolutions.alloc(Default::default()) } fn alloc_macro_rules_scope(&'a self, scope: MacroRulesScope<'a>) -> MacroRulesScopeRef<'a> { Interned::new_unchecked(self.dropless.alloc(Cell::new(scope))) } fn alloc_macro_rules_binding( &'a self, binding: MacroRulesBinding<'a>, ) -> &'a MacroRulesBinding<'a> { self.dropless.alloc(binding) } fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] { self.ast_paths.alloc_from_iter(paths.iter().cloned()) } fn alloc_pattern_spans(&'a self, spans: impl Iterator) -> &'a [Span] { self.dropless.alloc_from_iter(spans) } } impl<'a> AsMut> for Resolver<'a> { fn as_mut(&mut self) -> &mut Resolver<'a> { self } } impl<'a, 'b> DefIdTree for &'a Resolver<'b> { fn parent(self, id: DefId) -> Option { match id.as_local() { Some(id) => self.definitions.def_key(id).parent, None => self.cstore().def_key(id).parent, } .map(|index| DefId { index, ..id }) } } /// This interface is used through the AST→HIR step, to embed full paths into the HIR. After that /// the resolver is no longer needed as all the relevant information is inline. impl ResolverAstLowering for Resolver<'_> { fn def_key(&self, id: DefId) -> DefKey { if let Some(id) = id.as_local() { self.definitions.def_key(id) } else { self.cstore().def_key(id) } } #[inline] fn def_span(&self, id: LocalDefId) -> Span { self.definitions.def_span(id) } fn item_generics_num_lifetimes(&self, def_id: DefId) -> usize { if let Some(def_id) = def_id.as_local() { self.item_generics_num_lifetimes[&def_id] } else { self.cstore().item_generics_num_lifetimes(def_id, self.session) } } fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option> { self.legacy_const_generic_args(expr) } fn get_partial_res(&self, id: NodeId) -> Option { self.partial_res_map.get(&id).cloned() } fn get_import_res(&self, id: NodeId) -> PerNS> { self.import_res_map.get(&id).cloned().unwrap_or_default() } fn get_label_res(&self, id: NodeId) -> Option { self.label_res_map.get(&id).cloned() } fn create_stable_hashing_context(&self) -> StableHashingContext<'_> { StableHashingContext::new(self.session, &self.definitions, self.crate_loader.cstore()) } fn definitions(&self) -> &Definitions { &self.definitions } fn next_node_id(&mut self) -> NodeId { self.next_node_id() } fn take_trait_map(&mut self, node: NodeId) -> Option> { self.trait_map.remove(&node) } fn opt_local_def_id(&self, node: NodeId) -> Option { self.node_id_to_def_id.get(&node).copied() } fn local_def_id(&self, node: NodeId) -> LocalDefId { self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{:?}`", node)) } fn def_path_hash(&self, def_id: DefId) -> DefPathHash { match def_id.as_local() { Some(def_id) => self.definitions.def_path_hash(def_id), None => self.cstore().def_path_hash(def_id), } } /// Adds a definition with a parent definition. fn create_def( &mut self, parent: LocalDefId, node_id: ast::NodeId, data: DefPathData, expn_id: ExpnId, span: Span, ) -> LocalDefId { assert!( !self.node_id_to_def_id.contains_key(&node_id), "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}", node_id, data, self.definitions.def_key(self.node_id_to_def_id[&node_id]), ); let def_id = self.definitions.create_def(parent, data, expn_id, span); // Some things for which we allocate `LocalDefId`s don't correspond to // anything in the AST, so they don't have a `NodeId`. For these cases // we don't need a mapping from `NodeId` to `LocalDefId`. if node_id != ast::DUMMY_NODE_ID { debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id); self.node_id_to_def_id.insert(node_id, def_id); } assert_eq!(self.def_id_to_node_id.push(node_id), def_id); def_id } fn decl_macro_kind(&self, def_id: LocalDefId) -> MacroKind { self.builtin_macro_kinds.get(&def_id).copied().unwrap_or(MacroKind::Bang) } } impl<'a> Resolver<'a> { pub fn new( session: &'a Session, krate: &Crate, crate_name: &str, metadata_loader: Box, arenas: &'a ResolverArenas<'a>, ) -> Resolver<'a> { let root_def_id = CRATE_DEF_ID.to_def_id(); let mut module_map = FxHashMap::default(); let graph_root = arenas.new_module( None, ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty), ExpnId::root(), krate.spans.inner_span, session.contains_name(&krate.attrs, sym::no_implicit_prelude), &mut module_map, ); let empty_module = arenas.new_module( None, ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty), ExpnId::root(), DUMMY_SP, true, &mut FxHashMap::default(), ); let definitions = Definitions::new(session.local_stable_crate_id(), krate.spans.inner_span); let root = definitions.get_root_def(); let mut visibilities = FxHashMap::default(); visibilities.insert(CRATE_DEF_ID, ty::Visibility::Public); let mut def_id_to_node_id = IndexVec::default(); assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), root); let mut node_id_to_def_id = FxHashMap::default(); node_id_to_def_id.insert(CRATE_NODE_ID, root); let mut invocation_parents = FxHashMap::default(); invocation_parents.insert(LocalExpnId::ROOT, (root, ImplTraitContext::Existential)); let mut extern_prelude: FxHashMap> = session .opts .externs .iter() .filter(|(_, entry)| entry.add_prelude) .map(|(name, _)| (Ident::from_str(name), Default::default())) .collect(); if !session.contains_name(&krate.attrs, sym::no_core) { extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default()); if !session.contains_name(&krate.attrs, sym::no_std) { extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default()); } } let (registered_attrs, registered_tools) = macros::registered_attrs_and_tools(session, &krate.attrs); let features = session.features_untracked(); let mut resolver = Resolver { session, definitions, // The outermost module has def ID 0; this is not reflected in the // AST. graph_root, prelude: None, extern_prelude, has_self: FxHashSet::default(), field_names: FxHashMap::default(), determined_imports: Vec::new(), indeterminate_imports: Vec::new(), pat_span_map: Default::default(), partial_res_map: Default::default(), import_res_map: Default::default(), label_res_map: Default::default(), extern_crate_map: Default::default(), reexport_map: FxHashMap::default(), trait_map: NodeMap::default(), underscore_disambiguator: 0, empty_module, module_map, block_map: Default::default(), binding_parent_modules: FxHashMap::default(), ast_transform_scopes: FxHashMap::default(), glob_map: Default::default(), visibilities, used_imports: FxHashSet::default(), maybe_unused_trait_imports: Default::default(), maybe_unused_extern_crates: Vec::new(), privacy_errors: Vec::new(), ambiguity_errors: Vec::new(), use_injections: Vec::new(), macro_expanded_macro_export_errors: BTreeSet::new(), arenas, dummy_binding: arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Res(Res::Err, false), ambiguity: None, expansion: LocalExpnId::ROOT, span: DUMMY_SP, vis: ty::Visibility::Public, }), crate_loader: CrateLoader::new(session, metadata_loader, crate_name), macro_names: FxHashSet::default(), builtin_macros: Default::default(), builtin_macro_kinds: Default::default(), registered_attrs, registered_tools, macro_use_prelude: FxHashMap::default(), all_macro_rules: Default::default(), macro_map: FxHashMap::default(), dummy_ext_bang: Lrc::new(SyntaxExtension::dummy_bang(session.edition())), dummy_ext_derive: Lrc::new(SyntaxExtension::dummy_derive(session.edition())), non_macro_attr: Lrc::new(SyntaxExtension::non_macro_attr(session.edition())), invocation_parent_scopes: Default::default(), output_macro_rules_scopes: Default::default(), helper_attrs: Default::default(), derive_data: Default::default(), local_macro_def_scopes: FxHashMap::default(), name_already_seen: FxHashMap::default(), potentially_unused_imports: Vec::new(), struct_constructors: Default::default(), unused_macros: Default::default(), proc_macro_stubs: Default::default(), single_segment_macro_resolutions: Default::default(), multi_segment_macro_resolutions: Default::default(), builtin_attrs: Default::default(), containers_deriving_copy: Default::default(), active_features: features .declared_lib_features .iter() .map(|(feat, ..)| *feat) .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat)) .collect(), lint_buffer: LintBuffer::default(), next_node_id: CRATE_NODE_ID, node_id_to_def_id, def_id_to_node_id, placeholder_field_indices: Default::default(), invocation_parents, trait_impl_items: Default::default(), legacy_const_generic_args: Default::default(), item_generics_num_lifetimes: Default::default(), main_def: Default::default(), trait_impls: Default::default(), proc_macros: Default::default(), confused_type_with_std_module: Default::default(), access_levels: Default::default(), }; let root_parent_scope = ParentScope::module(graph_root, &resolver); resolver.invocation_parent_scopes.insert(LocalExpnId::ROOT, root_parent_scope); resolver } fn new_module( &mut self, parent: Option>, kind: ModuleKind, expn_id: ExpnId, span: Span, no_implicit_prelude: bool, ) -> Module<'a> { let module_map = &mut self.module_map; self.arenas.new_module(parent, kind, expn_id, span, no_implicit_prelude, module_map) } pub fn next_node_id(&mut self) -> NodeId { let next = self.next_node_id.as_u32().checked_add(1).expect("input too large; ran out of NodeIds"); mem::replace(&mut self.next_node_id, ast::NodeId::from_u32(next)) } pub fn lint_buffer(&mut self) -> &mut LintBuffer { &mut self.lint_buffer } pub fn arenas() -> ResolverArenas<'a> { Default::default() } pub fn into_outputs(self) -> ResolverOutputs { let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect(); let definitions = self.definitions; let visibilities = self.visibilities; let extern_crate_map = self.extern_crate_map; let reexport_map = self.reexport_map; let maybe_unused_trait_imports = self.maybe_unused_trait_imports; let maybe_unused_extern_crates = self.maybe_unused_extern_crates; let glob_map = self.glob_map; let main_def = self.main_def; let confused_type_with_std_module = self.confused_type_with_std_module; let access_levels = self.access_levels; ResolverOutputs { definitions, cstore: Box::new(self.crate_loader.into_cstore()), visibilities, access_levels, extern_crate_map, reexport_map, glob_map, maybe_unused_trait_imports, maybe_unused_extern_crates, extern_prelude: self .extern_prelude .iter() .map(|(ident, entry)| (ident.name, entry.introduced_by_item)) .collect(), main_def, trait_impls: self.trait_impls, proc_macros, confused_type_with_std_module, registered_tools: self.registered_tools, } } pub fn clone_outputs(&self) -> ResolverOutputs { let proc_macros = self.proc_macros.iter().map(|id| self.local_def_id(*id)).collect(); ResolverOutputs { definitions: self.definitions.clone(), access_levels: self.access_levels.clone(), cstore: Box::new(self.cstore().clone()), visibilities: self.visibilities.clone(), extern_crate_map: self.extern_crate_map.clone(), reexport_map: self.reexport_map.clone(), glob_map: self.glob_map.clone(), maybe_unused_trait_imports: self.maybe_unused_trait_imports.clone(), maybe_unused_extern_crates: self.maybe_unused_extern_crates.clone(), extern_prelude: self .extern_prelude .iter() .map(|(ident, entry)| (ident.name, entry.introduced_by_item)) .collect(), main_def: self.main_def, trait_impls: self.trait_impls.clone(), proc_macros, confused_type_with_std_module: self.confused_type_with_std_module.clone(), registered_tools: self.registered_tools.clone(), } } pub fn cstore(&self) -> &CStore { self.crate_loader.cstore() } fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc { match macro_kind { MacroKind::Bang => self.dummy_ext_bang.clone(), MacroKind::Derive => self.dummy_ext_derive.clone(), MacroKind::Attr => self.non_macro_attr.clone(), } } /// Runs the function on each namespace. fn per_ns(&mut self, mut f: F) { f(self, TypeNS); f(self, ValueNS); f(self, MacroNS); } fn is_builtin_macro(&mut self, res: Res) -> bool { self.get_macro(res).map_or(false, |ext| ext.builtin_name.is_some()) } fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId { loop { match ctxt.outer_expn_data().macro_def_id { Some(def_id) => return def_id, None => ctxt.remove_mark(), }; } } /// Entry point to crate resolution. pub fn resolve_crate(&mut self, krate: &Crate) { self.session.time("resolve_crate", || { self.session.time("finalize_imports", || ImportResolver { r: self }.finalize_imports()); self.session.time("resolve_access_levels", || { AccessLevelsVisitor::compute_access_levels(self, krate) }); self.session.time("finalize_macro_resolutions", || self.finalize_macro_resolutions()); self.session.time("late_resolve_crate", || self.late_resolve_crate(krate)); self.session.time("resolve_main", || self.resolve_main()); self.session.time("resolve_check_unused", || self.check_unused(krate)); self.session.time("resolve_report_errors", || self.report_errors(krate)); self.session.time("resolve_postprocess", || self.crate_loader.postprocess(krate)); }); } pub fn traits_in_scope( &mut self, current_trait: Option>, parent_scope: &ParentScope<'a>, ctxt: SyntaxContext, assoc_item: Option<(Symbol, Namespace)>, ) -> Vec { let mut found_traits = Vec::new(); if let Some(module) = current_trait { if self.trait_may_have_item(Some(module), assoc_item) { let def_id = module.def_id(); found_traits.push(TraitCandidate { def_id, import_ids: smallvec![] }); } } self.visit_scopes(ScopeSet::All(TypeNS, false), parent_scope, ctxt, |this, scope, _, _| { match scope { Scope::Module(module, _) => { this.traits_in_module(module, assoc_item, &mut found_traits); } Scope::StdLibPrelude => { if let Some(module) = this.prelude { this.traits_in_module(module, assoc_item, &mut found_traits); } } Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {} _ => unreachable!(), } None::<()> }); found_traits } fn traits_in_module( &mut self, module: Module<'a>, assoc_item: Option<(Symbol, Namespace)>, found_traits: &mut Vec, ) { module.ensure_traits(self); let traits = module.traits.borrow(); for (trait_name, trait_binding) in traits.as_ref().unwrap().iter() { if self.trait_may_have_item(trait_binding.module(), assoc_item) { let def_id = trait_binding.res().def_id(); let import_ids = self.find_transitive_imports(&trait_binding.kind, *trait_name); found_traits.push(TraitCandidate { def_id, import_ids }); } } } // List of traits in scope is pruned on best effort basis. We reject traits not having an // associated item with the given name and namespace (if specified). This is a conservative // optimization, proper hygienic type-based resolution of associated items is done in typeck. // We don't reject trait aliases (`trait_module == None`) because we don't have access to their // associated items. fn trait_may_have_item( &mut self, trait_module: Option>, assoc_item: Option<(Symbol, Namespace)>, ) -> bool { match (trait_module, assoc_item) { (Some(trait_module), Some((name, ns))) => { self.resolutions(trait_module).borrow().iter().any(|resolution| { let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution; assoc_ns == ns && assoc_ident.name == name }) } _ => true, } } fn find_transitive_imports( &mut self, mut kind: &NameBindingKind<'_>, trait_name: Ident, ) -> SmallVec<[LocalDefId; 1]> { let mut import_ids = smallvec![]; while let NameBindingKind::Import { import, binding, .. } = kind { let id = self.local_def_id(import.id); self.maybe_unused_trait_imports.insert(id); self.add_to_glob_map(&import, trait_name); import_ids.push(id); kind = &binding.kind; } import_ids } fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey { let ident = ident.normalize_to_macros_2_0(); let disambiguator = if ident.name == kw::Underscore { self.underscore_disambiguator += 1; self.underscore_disambiguator } else { 0 }; BindingKey { ident, ns, disambiguator } } fn resolutions(&mut self, module: Module<'a>) -> &'a Resolutions<'a> { if module.populate_on_access.get() { module.populate_on_access.set(false); self.build_reduced_graph_external(module); } &module.lazy_resolutions } fn resolution( &mut self, module: Module<'a>, key: BindingKey, ) -> &'a RefCell> { *self .resolutions(module) .borrow_mut() .entry(key) .or_insert_with(|| self.arenas.alloc_name_resolution()) } fn record_use( &mut self, ident: Ident, used_binding: &'a NameBinding<'a>, is_lexical_scope: bool, ) { if let Some((b2, kind)) = used_binding.ambiguity { self.ambiguity_errors.push(AmbiguityError { kind, ident, b1: used_binding, b2, misc1: AmbiguityErrorMisc::None, misc2: AmbiguityErrorMisc::None, }); } if let NameBindingKind::Import { import, binding, ref used } = used_binding.kind { // Avoid marking `extern crate` items that refer to a name from extern prelude, // but not introduce it, as used if they are accessed from lexical scope. if is_lexical_scope { if let Some(entry) = self.extern_prelude.get(&ident.normalize_to_macros_2_0()) { if let Some(crate_item) = entry.extern_crate_item { if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item { return; } } } } used.set(true); import.used.set(true); self.used_imports.insert(import.id); self.add_to_glob_map(&import, ident); self.record_use(ident, binding, false); } } #[inline] fn add_to_glob_map(&mut self, import: &Import<'_>, ident: Ident) { if import.is_glob() { let def_id = self.local_def_id(import.id); self.glob_map.entry(def_id).or_default().insert(ident.name); } } fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> { debug!("resolve_crate_root({:?})", ident); let mut ctxt = ident.span.ctxt(); let mark = if ident.name == kw::DollarCrate { // When resolving `$crate` from a `macro_rules!` invoked in a `macro`, // we don't want to pretend that the `macro_rules!` definition is in the `macro` // as described in `SyntaxContext::apply_mark`, so we ignore prepended opaque marks. // FIXME: This is only a guess and it doesn't work correctly for `macro_rules!` // definitions actually produced by `macro` and `macro` definitions produced by // `macro_rules!`, but at least such configurations are not stable yet. ctxt = ctxt.normalize_to_macro_rules(); debug!( "resolve_crate_root: marks={:?}", ctxt.marks().into_iter().map(|(i, t)| (i.expn_data(), t)).collect::>() ); let mut iter = ctxt.marks().into_iter().rev().peekable(); let mut result = None; // Find the last opaque mark from the end if it exists. while let Some(&(mark, transparency)) = iter.peek() { if transparency == Transparency::Opaque { result = Some(mark); iter.next(); } else { break; } } debug!( "resolve_crate_root: found opaque mark {:?} {:?}", result, result.map(|r| r.expn_data()) ); // Then find the last semi-transparent mark from the end if it exists. for (mark, transparency) in iter { if transparency == Transparency::SemiTransparent { result = Some(mark); } else { break; } } debug!( "resolve_crate_root: found semi-transparent mark {:?} {:?}", result, result.map(|r| r.expn_data()) ); result } else { debug!("resolve_crate_root: not DollarCrate"); ctxt = ctxt.normalize_to_macros_2_0(); ctxt.adjust(ExpnId::root()) }; let module = match mark { Some(def) => self.expn_def_scope(def), None => { debug!( "resolve_crate_root({:?}): found no mark (ident.span = {:?})", ident, ident.span ); return self.graph_root; } }; let module = self.expect_module( module.opt_def_id().map_or(LOCAL_CRATE, |def_id| def_id.krate).as_def_id(), ); debug!( "resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})", ident, module, module.kind.name(), ident.span ); module } fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> { let mut module = self.expect_module(module.nearest_parent_mod()); while module.span.ctxt().normalize_to_macros_2_0() != *ctxt { let parent = module.parent.unwrap_or_else(|| self.expn_def_scope(ctxt.remove_mark())); module = self.expect_module(parent.nearest_parent_mod()); } module } fn lint_if_path_starts_with_module( &mut self, finalize: Finalize, path: &[Segment], second_binding: Option<&NameBinding<'_>>, ) { let (diag_id, diag_span) = match finalize { Finalize::No => return, Finalize::SimplePath(id, path_span) => (id, path_span), Finalize::UsePath { root_id, root_span, .. } => (root_id, root_span), Finalize::QPathTrait { qpath_id, qpath_span, .. } => (qpath_id, qpath_span), }; let first_name = match path.get(0) { // In the 2018 edition this lint is a hard error, so nothing to do Some(seg) if seg.ident.span.rust_2015() && self.session.rust_2015() => seg.ident.name, _ => return, }; // We're only interested in `use` paths which should start with // `{{root}}` currently. if first_name != kw::PathRoot { return; } match path.get(1) { // If this import looks like `crate::...` it's already good Some(Segment { ident, .. }) if ident.name == kw::Crate => return, // Otherwise go below to see if it's an extern crate Some(_) => {} // If the path has length one (and it's `PathRoot` most likely) // then we don't know whether we're gonna be importing a crate or an // item in our crate. Defer this lint to elsewhere None => return, } // If the first element of our path was actually resolved to an // `ExternCrate` (also used for `crate::...`) then no need to issue a // warning, this looks all good! if let Some(binding) = second_binding { if let NameBindingKind::Import { import, .. } = binding.kind { // Careful: we still want to rewrite paths from renamed extern crates. if let ImportKind::ExternCrate { source: None, .. } = import.kind { return; } } } let diag = BuiltinLintDiagnostics::AbsPathWithModule(diag_span); self.lint_buffer.buffer_lint_with_diagnostic( lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE, diag_id, diag_span, "absolute paths must start with `self`, `super`, \ `crate`, or an external crate name in the 2018 edition", diag, ); } fn record_partial_res(&mut self, node_id: NodeId, resolution: PartialRes) { debug!("(recording res) recording {:?} for {}", resolution, node_id); if let Some(prev_res) = self.partial_res_map.insert(node_id, resolution) { panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution); } } fn record_pat_span(&mut self, node: NodeId, span: Span) { debug!("(recording pat) recording {:?} for {:?}", node, span); self.pat_span_map.insert(node, span); } fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool { vis.is_accessible_from(module.nearest_parent_mod(), self) } fn set_binding_parent_module(&mut self, binding: &'a NameBinding<'a>, module: Module<'a>) { if let Some(old_module) = self.binding_parent_modules.insert(Interned::new_unchecked(binding), module) { if !ptr::eq(module, old_module) { span_bug!(binding.span, "parent module is reset for binding"); } } } fn disambiguate_macro_rules_vs_modularized( &self, macro_rules: &'a NameBinding<'a>, modularized: &'a NameBinding<'a>, ) -> bool { // Some non-controversial subset of ambiguities "modularized macro name" vs "macro_rules" // is disambiguated to mitigate regressions from macro modularization. // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general. match ( self.binding_parent_modules.get(&Interned::new_unchecked(macro_rules)), self.binding_parent_modules.get(&Interned::new_unchecked(modularized)), ) { (Some(macro_rules), Some(modularized)) => { macro_rules.nearest_parent_mod() == modularized.nearest_parent_mod() && modularized.is_ancestor_of(macro_rules) } _ => false, } } fn report_errors(&mut self, krate: &Crate) { self.report_with_use_injections(krate); for &(span_use, span_def) in &self.macro_expanded_macro_export_errors { let msg = "macro-expanded `macro_export` macros from the current crate \ cannot be referred to by absolute paths"; self.lint_buffer.buffer_lint_with_diagnostic( lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS, CRATE_NODE_ID, span_use, msg, BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def), ); } for ambiguity_error in &self.ambiguity_errors { self.report_ambiguity_error(ambiguity_error); } let mut reported_spans = FxHashSet::default(); for error in &self.privacy_errors { if reported_spans.insert(error.dedup_span) { self.report_privacy_error(error); } } } fn report_with_use_injections(&mut self, krate: &Crate) { for UseError { mut err, candidates, def_id, instead, suggestion } in self.use_injections.drain(..) { let (span, found_use) = if let Some(def_id) = def_id.as_local() { UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id]) } else { (None, false) }; if !candidates.is_empty() { diagnostics::show_candidates( &self.definitions, self.session, &mut err, span, &candidates, instead, found_use, ); } else if let Some((span, msg, sugg, appl)) = suggestion { err.span_suggestion(span, msg, sugg, appl); } err.emit(); } } fn report_conflict<'b>( &mut self, parent: Module<'_>, ident: Ident, ns: Namespace, new_binding: &NameBinding<'b>, old_binding: &NameBinding<'b>, ) { // Error on the second of two conflicting names if old_binding.span.lo() > new_binding.span.lo() { return self.report_conflict(parent, ident, ns, old_binding, new_binding); } let container = match parent.kind { ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()), ModuleKind::Block(..) => "block", }; let old_noun = match old_binding.is_import() { true => "import", false => "definition", }; let new_participle = match new_binding.is_import() { true => "imported", false => "defined", }; let (name, span) = (ident.name, self.session.source_map().guess_head_span(new_binding.span)); if let Some(s) = self.name_already_seen.get(&name) { if s == &span { return; } } let old_kind = match (ns, old_binding.module()) { (ValueNS, _) => "value", (MacroNS, _) => "macro", (TypeNS, _) if old_binding.is_extern_crate() => "extern crate", (TypeNS, Some(module)) if module.is_normal() => "module", (TypeNS, Some(module)) if module.is_trait() => "trait", (TypeNS, _) => "type", }; let msg = format!("the name `{}` is defined multiple times", name); let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) { (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg), (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() { true => struct_span_err!(self.session, span, E0254, "{}", msg), false => struct_span_err!(self.session, span, E0260, "{}", msg), }, _ => match (old_binding.is_import(), new_binding.is_import()) { (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg), (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg), _ => struct_span_err!(self.session, span, E0255, "{}", msg), }, }; err.note(&format!( "`{}` must be defined only once in the {} namespace of this {}", name, ns.descr(), container )); err.span_label(span, format!("`{}` re{} here", name, new_participle)); err.span_label( self.session.source_map().guess_head_span(old_binding.span), format!("previous {} of the {} `{}` here", old_noun, old_kind, name), ); // See https://github.com/rust-lang/rust/issues/32354 use NameBindingKind::Import; let import = match (&new_binding.kind, &old_binding.kind) { // If there are two imports where one or both have attributes then prefer removing the // import without attributes. (Import { import: new, .. }, Import { import: old, .. }) if { !new_binding.span.is_dummy() && !old_binding.span.is_dummy() && (new.has_attributes || old.has_attributes) } => { if old.has_attributes { Some((new, new_binding.span, true)) } else { Some((old, old_binding.span, true)) } } // Otherwise prioritize the new binding. (Import { import, .. }, other) if !new_binding.span.is_dummy() => { Some((import, new_binding.span, other.is_import())) } (other, Import { import, .. }) if !old_binding.span.is_dummy() => { Some((import, old_binding.span, other.is_import())) } _ => None, }; // Check if the target of the use for both bindings is the same. let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id(); let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy(); let from_item = self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item); // Only suggest removing an import if both bindings are to the same def, if both spans // aren't dummy spans. Further, if both bindings are imports, then the ident must have // been introduced by an item. let should_remove_import = duplicate && !has_dummy_span && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item); match import { Some((import, span, true)) if should_remove_import && import.is_nested() => { self.add_suggestion_for_duplicate_nested_use(&mut err, import, span) } Some((import, _, true)) if should_remove_import && !import.is_glob() => { // Simple case - remove the entire import. Due to the above match arm, this can // only be a single use so just remove it entirely. err.tool_only_span_suggestion( import.use_span_with_attributes, "remove unnecessary import", String::new(), Applicability::MaybeIncorrect, ); } Some((import, span, _)) => { self.add_suggestion_for_rename_of_use(&mut err, name, import, span) } _ => {} } err.emit(); self.name_already_seen.insert(name, span); } /// This function adds a suggestion to change the binding name of a new import that conflicts /// with an existing import. /// /// ```text,ignore (diagnostic) /// help: you can use `as` to change the binding name of the import /// | /// LL | use foo::bar as other_bar; /// | ^^^^^^^^^^^^^^^^^^^^^ /// ``` fn add_suggestion_for_rename_of_use( &self, err: &mut Diagnostic, name: Symbol, import: &Import<'_>, binding_span: Span, ) { let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() { format!("Other{}", name) } else { format!("other_{}", name) }; let mut suggestion = None; match import.kind { ImportKind::Single { type_ns_only: true, .. } => { suggestion = Some(format!("self as {}", suggested_name)) } ImportKind::Single { source, .. } => { if let Some(pos) = source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize) { if let Ok(snippet) = self.session.source_map().span_to_snippet(binding_span) { if pos <= snippet.len() { suggestion = Some(format!( "{} as {}{}", &snippet[..pos], suggested_name, if snippet.ends_with(';') { ";" } else { "" } )) } } } } ImportKind::ExternCrate { source, target } => { suggestion = Some(format!( "extern crate {} as {};", source.unwrap_or(target.name), suggested_name, )) } _ => unreachable!(), } let rename_msg = "you can use `as` to change the binding name of the import"; if let Some(suggestion) = suggestion { err.span_suggestion( binding_span, rename_msg, suggestion, Applicability::MaybeIncorrect, ); } else { err.span_label(binding_span, rename_msg); } } /// This function adds a suggestion to remove an unnecessary binding from an import that is /// nested. In the following example, this function will be invoked to remove the `a` binding /// in the second use statement: /// /// ```ignore (diagnostic) /// use issue_52891::a; /// use issue_52891::{d, a, e}; /// ``` /// /// The following suggestion will be added: /// /// ```ignore (diagnostic) /// use issue_52891::{d, a, e}; /// ^-- help: remove unnecessary import /// ``` /// /// If the nested use contains only one import then the suggestion will remove the entire /// line. /// /// It is expected that the provided import is nested - this isn't checked by the /// function. If this invariant is not upheld, this function's behaviour will be unexpected /// as characters expected by span manipulations won't be present. fn add_suggestion_for_duplicate_nested_use( &self, err: &mut Diagnostic, import: &Import<'_>, binding_span: Span, ) { assert!(import.is_nested()); let message = "remove unnecessary import"; // Two examples will be used to illustrate the span manipulations we're doing: // // - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is // `a` and `import.use_span` is `issue_52891::{d, a, e};`. // - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is // `a` and `import.use_span` is `issue_52891::{d, e, a};`. let (found_closing_brace, span) = find_span_of_binding_until_next_binding(self.session, binding_span, import.use_span); // If there was a closing brace then identify the span to remove any trailing commas from // previous imports. if found_closing_brace { if let Some(span) = extend_span_to_previous_binding(self.session, span) { err.tool_only_span_suggestion( span, message, String::new(), Applicability::MaybeIncorrect, ); } else { // Remove the entire line if we cannot extend the span back, this indicates an // `issue_52891::{self}` case. err.span_suggestion( import.use_span_with_attributes, message, String::new(), Applicability::MaybeIncorrect, ); } return; } err.span_suggestion(span, message, String::new(), Applicability::MachineApplicable); } fn extern_prelude_get(&mut self, ident: Ident, finalize: bool) -> Option<&'a NameBinding<'a>> { if ident.is_path_segment_keyword() { // Make sure `self`, `super` etc produce an error when passed to here. return None; } self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| { if let Some(binding) = entry.extern_crate_item { if finalize && entry.introduced_by_item { self.record_use(ident, binding, false); } Some(binding) } else { let crate_id = if finalize { let Some(crate_id) = self.crate_loader.process_path_extern(ident.name, ident.span) else { return Some(self.dummy_binding); }; crate_id } else { self.crate_loader.maybe_process_path_extern(ident.name)? }; let crate_root = self.expect_module(crate_id.as_def_id()); Some( (crate_root, ty::Visibility::Public, DUMMY_SP, LocalExpnId::ROOT) .to_name_binding(self.arenas), ) } }) } /// Rustdoc uses this to resolve doc link paths in a recoverable way. `PathResult<'a>` /// isn't something that can be returned because it can't be made to live that long, /// and also it's a private type. Fortunately rustdoc doesn't need to know the error, /// just that an error occurred. pub fn resolve_rustdoc_path( &mut self, path_str: &str, ns: Namespace, mut module_id: DefId, ) -> Option { let mut segments = Vec::from_iter(path_str.split("::").map(Ident::from_str).map(Segment::from_ident)); if let Some(segment) = segments.first_mut() { if segment.ident.name == kw::Crate { // FIXME: `resolve_path` always resolves `crate` to the current crate root, but // rustdoc wants it to resolve to the `module_id`'s crate root. This trick of // replacing `crate` with `self` and changing the current module should achieve // the same effect. segment.ident.name = kw::SelfLower; module_id = module_id.krate.as_def_id(); } else if segment.ident.name == kw::Empty { segment.ident.name = kw::PathRoot; } } let module = self.expect_module(module_id); match self.maybe_resolve_path(&segments, Some(ns), &ParentScope::module(module, self)) { PathResult::Module(ModuleOrUniformRoot::Module(module)) => Some(module.res().unwrap()), PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => { Some(path_res.base_res()) } PathResult::Module(ModuleOrUniformRoot::ExternPrelude) | PathResult::NonModule(..) | PathResult::Failed { .. } => None, PathResult::Module(..) | PathResult::Indeterminate => unreachable!(), } } // For rustdoc. pub fn graph_root(&self) -> Module<'a> { self.graph_root } // For rustdoc. pub fn take_all_macro_rules(&mut self) -> FxHashMap { mem::take(&mut self.all_macro_rules) } /// For rustdoc. /// For local modules returns only reexports, for external modules returns all children. pub fn module_children_or_reexports(&self, def_id: DefId) -> Vec { if let Some(def_id) = def_id.as_local() { self.reexport_map.get(&def_id).cloned().unwrap_or_default() } else { self.cstore().module_children_untracked(def_id, self.session) } } /// Retrieves the span of the given `DefId` if `DefId` is in the local crate. #[inline] pub fn opt_span(&self, def_id: DefId) -> Option { def_id.as_local().map(|def_id| self.definitions.def_span(def_id)) } /// Checks if an expression refers to a function marked with /// `#[rustc_legacy_const_generics]` and returns the argument index list /// from the attribute. pub fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option> { if let ExprKind::Path(None, path) = &expr.kind { // Don't perform legacy const generics rewriting if the path already // has generic arguments. if path.segments.last().unwrap().args.is_some() { return None; } let partial_res = self.partial_res_map.get(&expr.id)?; if partial_res.unresolved_segments() != 0 { return None; } if let Res::Def(def::DefKind::Fn, def_id) = partial_res.base_res() { // We only support cross-crate argument rewriting. Uses // within the same crate should be updated to use the new // const generics style. if def_id.is_local() { return None; } if let Some(v) = self.legacy_const_generic_args.get(&def_id) { return v.clone(); } let attr = self .cstore() .item_attrs_untracked(def_id, self.session) .find(|a| a.has_name(sym::rustc_legacy_const_generics))?; let mut ret = Vec::new(); for meta in attr.meta_item_list()? { match meta.literal()?.kind { LitKind::Int(a, _) => ret.push(a as usize), _ => panic!("invalid arg index"), } } // Cache the lookup to avoid parsing attributes for an iterm multiple times. self.legacy_const_generic_args.insert(def_id, Some(ret.clone())); return Some(ret); } } None } fn resolve_main(&mut self) { let module = self.graph_root; let ident = Ident::with_dummy_span(sym::main); let parent_scope = &ParentScope::module(module, self); let Ok(name_binding) = self.maybe_resolve_ident_in_module( ModuleOrUniformRoot::Module(module), ident, ValueNS, parent_scope, ) else { return; }; let res = name_binding.res(); let is_import = name_binding.is_import(); let span = name_binding.span; if let Res::Def(DefKind::Fn, _) = res { self.record_use(ident, name_binding, false); } self.main_def = Some(MainDefinition { res, is_import, span }); } } fn names_to_string(names: &[Symbol]) -> String { let mut result = String::new(); for (i, name) in names.iter().filter(|name| **name != kw::PathRoot).enumerate() { if i > 0 { result.push_str("::"); } if Ident::with_dummy_span(*name).is_raw_guess() { result.push_str("r#"); } result.push_str(name.as_str()); } result } fn path_names_to_string(path: &Path) -> String { names_to_string(&path.segments.iter().map(|seg| seg.ident.name).collect::>()) } /// A somewhat inefficient routine to obtain the name of a module. fn module_to_string(module: Module<'_>) -> Option { let mut names = Vec::new(); fn collect_mod(names: &mut Vec, module: Module<'_>) { if let ModuleKind::Def(.., name) = module.kind { if let Some(parent) = module.parent { names.push(name); collect_mod(names, parent); } } else { names.push(Symbol::intern("")); collect_mod(names, module.parent.unwrap()); } } collect_mod(&mut names, module); if names.is_empty() { return None; } names.reverse(); Some(names_to_string(&names)) } #[derive(Copy, Clone, Debug)] enum Finalize { /// Do not issue the lint. No, /// This lint applies to some arbitrary path; e.g., `impl ::foo::Bar`. /// In this case, we can take the span of that path. SimplePath(NodeId, Span), /// This lint comes from a `use` statement. In this case, what we /// care about really is the *root* `use` statement; e.g., if we /// have nested things like `use a::{b, c}`, we care about the /// `use a` part. UsePath { root_id: NodeId, root_span: Span, path_span: Span }, /// This is the "trait item" from a fully qualified path. For example, /// we might be resolving `X::Y::Z` from a path like `::Z`. /// The `path_span` is the span of the to the trait itself (`X::Y`). QPathTrait { qpath_id: NodeId, qpath_span: Span, path_span: Span }, } impl Finalize { fn node_id_and_path_span(&self) -> Option<(NodeId, Span)> { match *self { Finalize::No => None, Finalize::SimplePath(id, path_span) | Finalize::UsePath { root_id: id, path_span, .. } | Finalize::QPathTrait { qpath_id: id, path_span, .. } => Some((id, path_span)), } } fn node_id(&self) -> Option { self.node_id_and_path_span().map(|(id, _)| id) } fn path_span(&self) -> Option { self.node_id_and_path_span().map(|(_, path_span)| path_span) } } pub fn provide(providers: &mut Providers) { late::lifetimes::provide(providers); }