//! 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 `librustc_typeck`. #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")] #![feature(bool_to_option)] #![feature(crate_visibility_modifier)] #![feature(label_break_value)] #![feature(nll)] #![cfg_attr(bootstrap, feature(slice_patterns))] #![recursion_limit = "256"] pub use rustc_hir::def::{Namespace, PerNS}; use Determinacy::*; use rustc::hir::exports::ExportMap; use rustc::hir::map::{DefKey, Definitions}; use rustc::lint; use rustc::middle::cstore::{CrateStore, MetadataLoaderDyn}; use rustc::span_bug; use rustc::ty::query::Providers; use rustc::ty::{self, DefIdTree, ResolverOutputs}; use rustc_ast_pretty::pprust; use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap}; use rustc_data_structures::ptr_key::PtrKey; use rustc_data_structures::sync::Lrc; use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder}; use rustc_expand::base::SyntaxExtension; use rustc_hir::def::Namespace::*; use rustc_hir::def::{self, CtorOf, DefKind, NonMacroAttrKind, PartialRes}; use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE}; use rustc_hir::PrimTy::{self, Bool, Char, Float, Int, Str, Uint}; use rustc_hir::{GlobMap, TraitMap}; use rustc_metadata::creader::{CStore, CrateLoader}; use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer}; use rustc_session::Session; use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency}; use rustc_span::source_map::Spanned; use rustc_span::symbol::{kw, sym}; use rustc_span::{Span, DUMMY_SP}; use syntax::ast::{self, FloatTy, Ident, IntTy, Name, NodeId, UintTy}; use syntax::ast::{Crate, CRATE_NODE_ID}; use syntax::ast::{ItemKind, Path}; use syntax::attr; use syntax::node_id::{NodeMap, NodeSet}; use syntax::unwrap_or; use syntax::visit::{self, Visitor}; use log::debug; use std::cell::{Cell, RefCell}; use std::collections::BTreeSet; use std::{cmp, fmt, iter, ptr}; use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding}; use diagnostics::{ImportSuggestion, Suggestion}; use imports::{ImportDirective, ImportDirectiveSubclass, ImportResolver, NameResolution}; use late::{HasGenericParams, PathSource, Rib, RibKind::*}; use macros::{LegacyBinding, LegacyScope}; type Res = def::Res; mod build_reduced_graph; mod check_unused; mod def_collector; mod diagnostics; mod imports; mod late; mod lifetimes; 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(ExpnId), DeriveHelpersCompat, MacroRules(LegacyScope<'a>), CrateRoot, Module(Module<'a>), 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. enum ScopeSet { /// 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), } /// 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: ExpnId, legacy: LegacyScope<'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>) -> ParentScope<'a> { ParentScope { module, expansion: ExpnId::root(), legacy: LegacyScope::Empty, derives: &[] } } } #[derive(Eq)] struct BindingError { name: Name, 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(Name, Span), /// Error E0407: method is not a member of trait. MethodNotMemberOfTrait(Name, &'a str), /// Error E0437: type is not a member of trait. TypeNotMemberOfTrait(Name, &'a str), /// Error E0438: const is not a member of trait. ConstNotMemberOfTrait(Name, &'a str), /// 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(Name, Span), /// Error E0415: identifier is bound more than once in this parameter list. IdentifierBoundMoreThanOnceInParameterList(&'a str), /// Error E0416: identifier is bound more than once in the same pattern. IdentifierBoundMoreThanOnceInSamePattern(&'a str), /// Error E0426: use of undeclared label. UndeclaredLabel(&'a str, Option), /// Error E0429: `self` imports are only allowed within a `{ }` list. SelfImportsOnlyAllowedWithin, /// 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, /// Error E0530: `X` bindings cannot shadow `Y`s. BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>), /// Error E0128: type parameters with a default cannot use forward-declared identifiers. ForwardDeclaredTyParam, // FIXME(const_generics:defaults) /// Error E0735: type parameters with a default cannot use `Self` SelfInTyParamDefault, } 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, } 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 } } 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) } } } struct UsePlacementFinder { target_module: NodeId, span: Option, found_use: bool, } impl UsePlacementFinder { fn check(krate: &Crate, target_module: NodeId) -> (Option, bool) { let mut finder = UsePlacementFinder { target_module, span: None, found_use: false }; visit::walk_crate(&mut finder, krate); (finder.span, finder.found_use) } } impl<'tcx> Visitor<'tcx> for UsePlacementFinder { fn visit_mod( &mut self, module: &'tcx ast::Mod, _: Span, _: &[ast::Attribute], node_id: NodeId, ) { if self.span.is_some() { return; } if node_id != self.target_module { visit::walk_mod(self, module); return; } // find a use statement for item in &module.items { match item.kind { ItemKind::Use(..) => { // don't suggest placing a use before the prelude // import or other generated ones if !item.span.from_expansion() { self.span = Some(item.span.shrink_to_lo()); self.found_use = true; return; } } // don't place use before extern crate ItemKind::ExternCrate(_) => {} // but place them before the first other item _ => { if self.span.map_or(true, |span| item.span < span) { if !item.span.from_expansion() { // don't insert between attributes and an item if item.attrs.is_empty() { self.span = Some(item.span.shrink_to_lo()); } else { // find the first attribute on the item for attr in &item.attrs { if self.span.map_or(true, |span| attr.span < span) { self.span = Some(attr.span.shrink_to_lo()); } } } } } } } } } } /// 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 item(self) -> Option<&'a NameBinding<'a>> { match self { LexicalScopeBinding::Item(binding) => Some(binding), _ => None, } } 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)) => { lhs.def_id() == rhs.def_id() } ( 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, }, } 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 { }`. /// * A trait or an enum (it implicitly contains associated types, methods and variant /// constructors). Def(DefKind, DefId, Name), } 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)] struct BindingKey { /// The identifier for the binding, aways the `modern` 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. pub struct ModuleData<'a> { parent: Option>, kind: ModuleKind, // The def id of the closest normal module (`mod`) ancestor (including this module). normal_ancestor_id: DefId, // 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>, 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, normal_ancestor_id: DefId, expansion: ExpnId, span: Span, ) -> Self { ModuleData { parent, kind, normal_ancestor_id, lazy_resolutions: Default::default(), populate_on_access: Cell::new(!normal_ancestor_id.is_local()), unexpanded_invocations: Default::default(), no_implicit_prelude: false, 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() { name_resolution.borrow().binding.map(|binding| f(resolver, key.ident, key.ns, binding)); } } fn res(&self) -> Option { match self.kind { ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)), _ => None, } } fn 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 { match self.kind { ModuleKind::Def(DefKind::Mod, _, _) => true, _ => false, } } fn is_trait(&self) -> bool { match self.kind { ModuleKind::Def(DefKind::Trait, _, _) => true, _ => false, } } fn nearest_item_scope(&'a self) -> Module<'a> { match self.kind { ModuleKind::Def(DefKind::Enum, ..) | ModuleKind::Def(DefKind::Trait, ..) => { self.parent.expect("enum or trait module without a parent") } _ => self, } } 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: ExpnId, 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>, directive: &'a ImportDirective<'a>, used: Cell }, } impl<'a> NameBindingKind<'a> { /// Is this a name binding of a import? fn is_import(&self) -> bool { match *self { NameBindingKind::Import { .. } => true, _ => false, } } } struct PrivacyError<'a> { ident: Ident, binding: &'a NameBinding<'a>, dedup_span: Span, } struct UseError<'a> { err: DiagnosticBuilder<'a>, /// Attach `use` statements for these candidates. candidates: Vec, /// The `NodeId` of the module to place the use-statements in. node_id: NodeId, /// Whether the diagnostic should state that it's "better". better: bool, /// Extra free form suggestion. Currently used to suggest new type parameter. suggestion: Option<(Span, &'static str, String, Applicability)>, } #[derive(Clone, Copy, PartialEq, Debug)] enum AmbiguityKind { Import, BuiltinAttr, DeriveHelper, LegacyVsModern, GlobVsOuter, GlobVsGlob, GlobVsExpanded, MoreExpandedVsOuter, } impl AmbiguityKind { fn descr(self) -> &'static str { match self { AmbiguityKind::Import => "name vs any other name during import resolution", AmbiguityKind::BuiltinAttr => "built-in attribute vs any other name", AmbiguityKind::DeriveHelper => "derive helper attribute vs any other name", AmbiguityKind::LegacyVsModern => "`macro_rules` vs non-`macro_rules` from other module", AmbiguityKind::GlobVsOuter => { "glob import vs any other name from outer scope during import/macro resolution" } AmbiguityKind::GlobVsGlob => "glob import vs glob import in the same module", AmbiguityKind::GlobVsExpanded => { "glob import vs macro-expanded name in the same \ module during import/macro resolution" } AmbiguityKind::MoreExpandedVsOuter => { "macro-expanded name vs less macro-expanded name \ from outer scope during import/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, } } // We sometimes need to treat variants as `pub` for backwards compatibility. fn pseudo_vis(&self) -> ty::Visibility { if self.is_variant() && self.res().def_id().is_local() { ty::Visibility::Public } else { self.vis } } fn is_variant(&self) -> bool { match self.kind { NameBindingKind::Res(Res::Def(DefKind::Variant, _), _) | NameBindingKind::Res(Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _), _) => true, _ => false, } } fn is_extern_crate(&self) -> bool { match self.kind { NameBindingKind::Import { directive: &ImportDirective { subclass: ImportDirectiveSubclass::ExternCrate { .. }, .. }, .. } => true, NameBindingKind::Module(&ModuleData { kind: ModuleKind::Def(DefKind::Mod, def_id, _), .. }) => def_id.index == CRATE_DEF_INDEX, _ => false, } } fn is_import(&self) -> bool { match self.kind { NameBindingKind::Import { .. } => true, _ => false, } } fn is_glob_import(&self) -> bool { match self.kind { NameBindingKind::Import { directive, .. } => directive.is_glob(), _ => false, } } fn is_importable(&self) -> bool { match self.res() { Res::Def(DefKind::AssocConst, _) | Res::Def(DefKind::Method, _) | Res::Def(DefKind::AssocTy, _) => false, _ => true, } } fn is_macro_def(&self) -> bool { match self.kind { NameBindingKind::Res(Res::Def(DefKind::Macro(..), _), _) => true, _ => false, } } 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: ExpnId, 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) } } /// Interns the names of the primitive types. /// /// All other types are defined somewhere and possibly imported, but the primitive ones need /// special handling, since they have no place of origin. struct PrimitiveTypeTable { primitive_types: FxHashMap, } impl PrimitiveTypeTable { fn new() -> PrimitiveTypeTable { let mut table = FxHashMap::default(); table.insert(sym::bool, Bool); table.insert(sym::char, Char); table.insert(sym::f32, Float(FloatTy::F32)); table.insert(sym::f64, Float(FloatTy::F64)); table.insert(sym::isize, Int(IntTy::Isize)); table.insert(sym::i8, Int(IntTy::I8)); table.insert(sym::i16, Int(IntTy::I16)); table.insert(sym::i32, Int(IntTy::I32)); table.insert(sym::i64, Int(IntTy::I64)); table.insert(sym::i128, Int(IntTy::I128)); table.insert(sym::str, Str); table.insert(sym::usize, Uint(UintTy::Usize)); table.insert(sym::u8, Uint(UintTy::U8)); table.insert(sym::u16, Uint(UintTy::U16)); table.insert(sym::u32, Uint(UintTy::U32)); table.insert(sym::u64, Uint(UintTy::U64)); table.insert(sym::u128, Uint(UintTy::U128)); Self { primitive_types: table } } } #[derive(Debug, Default, Clone)] pub struct ExternPreludeEntry<'a> { extern_crate_item: Option<&'a NameBinding<'a>>, pub introduced_by_item: 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 ImportDirective<'a>>, /// All non-determined imports. indeterminate_imports: Vec<&'a ImportDirective<'a>>, /// FIXME: Refactor things so that these fields are passed through arguments and not resolver. /// We are resolving a last import segment during import validation. last_import_segment: bool, /// This binding should be ignored during in-module resolution, so that we don't get /// "self-confirming" import resolutions during import validation. blacklisted_binding: Option<&'a NameBinding<'a>>, /// The idents for the primitive types. primitive_type_table: PrimitiveTypeTable, /// 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: NodeMap, export_map: ExportMap, trait_map: TraitMap, /// 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>, extern_module_map: FxHashMap>, binding_parent_modules: FxHashMap>, Module<'a>>, underscore_disambiguator: u32, /// Maps glob imports to the names of items actually imported. glob_map: GlobMap, used_imports: FxHashSet<(NodeId, Namespace)>, maybe_unused_trait_imports: NodeSet, maybe_unused_extern_crates: Vec<(NodeId, 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, registered_attrs: FxHashSet, registered_tools: FxHashSet, macro_use_prelude: FxHashMap>, all_macros: FxHashMap, macro_map: FxHashMap>, dummy_ext_bang: Lrc, dummy_ext_derive: Lrc, non_macro_attrs: [Lrc; 2], macro_defs: FxHashMap, local_macro_def_scopes: FxHashMap>, ast_transform_scopes: FxHashMap>, unused_macros: NodeMap, proc_macro_stubs: NodeSet, /// 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>, /// Legacy scopes *produced* by expanding the macro invocations, /// include all the `macro_rules` items and other invocations generated by them. output_legacy_scopes: FxHashMap>, /// Helper attributes that are in scope for the given expansion. helper_attrs: FxHashMap>, /// Avoid duplicated errors for "name already defined". name_already_seen: FxHashMap, potentially_unused_imports: Vec<&'a ImportDirective<'a>>, /// Table for mapping struct IDs into struct constructor IDs, /// it's not used during normal resolution, only for better error reporting. struct_constructors: DefIdMap<(Res, ty::Visibility)>, /// Features enabled for this crate. active_features: FxHashSet, /// Stores enum visibilities to properly build a reduced graph /// when visiting the correspondent variants. variant_vis: DefIdMap, lint_buffer: LintBuffer, next_node_id: NodeId, } /// Nothing really interesting here; it just provides memory for the rest of the crate. #[derive(Default)] pub struct ResolverArenas<'a> { modules: arena::TypedArena>, local_modules: RefCell>>, name_bindings: arena::TypedArena>, import_directives: arena::TypedArena>, name_resolutions: arena::TypedArena>>, legacy_bindings: arena::TypedArena>, ast_paths: arena::TypedArena, } impl<'a> ResolverArenas<'a> { fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> { let module = self.modules.alloc(module); if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) { self.local_modules.borrow_mut().push(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.name_bindings.alloc(name_binding) } fn alloc_import_directive( &'a self, import_directive: ImportDirective<'a>, ) -> &'a ImportDirective<'_> { self.import_directives.alloc(import_directive) } fn alloc_name_resolution(&'a self) -> &'a RefCell> { self.name_resolutions.alloc(Default::default()) } fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> { self.legacy_bindings.alloc(binding) } fn alloc_ast_paths(&'a self, paths: &[ast::Path]) -> &'a [ast::Path] { self.ast_paths.alloc_from_iter(paths.iter().cloned()) } } 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.krate { LOCAL_CRATE => self.definitions.def_key(id.index).parent, _ => 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 rustc_ast_lowering::Resolver for Resolver<'_> { fn def_key(&mut self, id: DefId) -> DefKey { if id.is_local() { self.definitions().def_key(id.index) } else { self.cstore().def_key(id) } } fn item_generics_num_lifetimes(&self, def_id: DefId, sess: &Session) -> usize { self.cstore().item_generics_num_lifetimes(def_id, sess) } fn resolve_str_path( &mut self, span: Span, crate_root: Option, components: &[Name], ns: Namespace, ) -> (ast::Path, Res) { let root = if crate_root.is_some() { kw::PathRoot } else { kw::Crate }; let segments = iter::once(Ident::with_dummy_span(root)) .chain( crate_root .into_iter() .chain(components.iter().cloned()) .map(Ident::with_dummy_span), ) .map(|i| self.new_ast_path_segment(i)) .collect::>(); let path = ast::Path { span, segments }; let parent_scope = &ParentScope::module(self.graph_root); let res = match self.resolve_ast_path(&path, ns, parent_scope) { Ok(res) => res, Err((span, error)) => { self.report_error(span, error); Res::Err } }; (path, res) } fn get_partial_res(&mut self, id: NodeId) -> Option { self.partial_res_map.get(&id).cloned() } fn get_import_res(&mut self, id: NodeId) -> PerNS> { self.import_res_map.get(&id).cloned().unwrap_or_default() } fn get_label_res(&mut self, id: NodeId) -> Option { self.label_res_map.get(&id).cloned() } fn definitions(&mut self) -> &mut Definitions { &mut self.definitions } fn lint_buffer(&mut self) -> &mut LintBuffer { &mut self.lint_buffer } fn next_node_id(&mut self) -> NodeId { self.next_node_id() } } impl<'a> Resolver<'a> { pub fn new( session: &'a Session, krate: &Crate, crate_name: &str, metadata_loader: &'a MetadataLoaderDyn, arenas: &'a ResolverArenas<'a>, ) -> Resolver<'a> { let root_def_id = DefId::local(CRATE_DEF_INDEX); let root_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid); let graph_root = arenas.alloc_module(ModuleData { no_implicit_prelude: attr::contains_name(&krate.attrs, sym::no_implicit_prelude), ..ModuleData::new(None, root_module_kind, root_def_id, ExpnId::root(), krate.span) }); let empty_module_kind = ModuleKind::Def(DefKind::Mod, root_def_id, kw::Invalid); let empty_module = arenas.alloc_module(ModuleData { no_implicit_prelude: true, ..ModuleData::new( Some(graph_root), empty_module_kind, root_def_id, ExpnId::root(), DUMMY_SP, ) }); let mut module_map = FxHashMap::default(); module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root); let mut definitions = Definitions::default(); definitions.create_root_def(crate_name, session.local_crate_disambiguator()); let mut extern_prelude: FxHashMap> = session .opts .externs .iter() .filter(|(_, entry)| entry.add_prelude) .map(|(name, _)| (Ident::from_str(name), Default::default())) .collect(); if !attr::contains_name(&krate.attrs, sym::no_core) { extern_prelude.insert(Ident::with_dummy_span(sym::core), Default::default()); if !attr::contains_name(&krate.attrs, sym::no_std) { extern_prelude.insert(Ident::with_dummy_span(sym::std), Default::default()); if session.rust_2018() { extern_prelude.insert(Ident::with_dummy_span(sym::meta), Default::default()); } } } let (registered_attrs, registered_tools) = macros::registered_attrs_and_tools(session, &krate.attrs); let mut invocation_parent_scopes = FxHashMap::default(); invocation_parent_scopes.insert(ExpnId::root(), ParentScope::module(graph_root)); let mut macro_defs = FxHashMap::default(); macro_defs.insert(ExpnId::root(), root_def_id); let features = session.features_untracked(); let non_macro_attr = |mark_used| Lrc::new(SyntaxExtension::non_macro_attr(mark_used, session.edition())); 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(), last_import_segment: false, blacklisted_binding: None, primitive_type_table: PrimitiveTypeTable::new(), partial_res_map: Default::default(), import_res_map: Default::default(), label_res_map: Default::default(), extern_crate_map: Default::default(), export_map: FxHashMap::default(), trait_map: Default::default(), underscore_disambiguator: 0, empty_module, module_map, block_map: Default::default(), extern_module_map: FxHashMap::default(), binding_parent_modules: FxHashMap::default(), ast_transform_scopes: FxHashMap::default(), glob_map: Default::default(), 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: ExpnId::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(), registered_attrs, registered_tools, macro_use_prelude: FxHashMap::default(), all_macros: FxHashMap::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_attrs: [non_macro_attr(false), non_macro_attr(true)], invocation_parent_scopes, output_legacy_scopes: Default::default(), helper_attrs: Default::default(), macro_defs, 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(), variant_vis: Default::default(), lint_buffer: LintBuffer::default(), next_node_id: NodeId::from_u32(1), } } pub fn next_node_id(&mut self) -> NodeId { let next = self .next_node_id .as_usize() .checked_add(1) .expect("input too large; ran out of NodeIds"); self.next_node_id = ast::NodeId::from_usize(next); self.next_node_id } 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 { ResolverOutputs { definitions: self.definitions, cstore: Box::new(self.crate_loader.into_cstore()), extern_crate_map: self.extern_crate_map, export_map: self.export_map, trait_map: self.trait_map, glob_map: self.glob_map, maybe_unused_trait_imports: self.maybe_unused_trait_imports, maybe_unused_extern_crates: self.maybe_unused_extern_crates, extern_prelude: self .extern_prelude .iter() .map(|(ident, entry)| (ident.name, entry.introduced_by_item)) .collect(), } } pub fn clone_outputs(&self) -> ResolverOutputs { ResolverOutputs { definitions: self.definitions.clone(), cstore: Box::new(self.cstore().clone()), extern_crate_map: self.extern_crate_map.clone(), export_map: self.export_map.clone(), trait_map: self.trait_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(), } } pub fn cstore(&self) -> &CStore { self.crate_loader.cstore() } fn non_macro_attr(&self, mark_used: bool) -> Lrc { self.non_macro_attrs[mark_used as usize].clone() } 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(true), } } /// 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.is_builtin) } fn macro_def(&self, mut ctxt: SyntaxContext) -> DefId { loop { match self.macro_defs.get(&ctxt.outer_expn()) { Some(&def_id) => return def_id, None => ctxt.remove_mark(), }; } } /// Entry point to crate resolution. pub fn resolve_crate(&mut self, krate: &Crate) { let _prof_timer = self.session.prof.generic_activity("resolve_crate"); ImportResolver { r: self }.finalize_imports(); self.finalize_macro_resolutions(); self.late_resolve_crate(krate); self.check_unused(krate); self.report_errors(krate); self.crate_loader.postprocess(krate); } fn new_module( &self, parent: Module<'a>, kind: ModuleKind, normal_ancestor_id: DefId, expn_id: ExpnId, span: Span, ) -> Module<'a> { let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expn_id, span); self.arenas.alloc_module(module) } fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey { let ident = ident.modern(); 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, ns: Namespace, 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 { directive, 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.modern()) { if let Some(crate_item) = entry.extern_crate_item { if ptr::eq(used_binding, crate_item) && !entry.introduced_by_item { return; } } } } used.set(true); directive.used.set(true); self.used_imports.insert((directive.id, ns)); self.add_to_glob_map(&directive, ident); self.record_use(ident, ns, binding, false); } } #[inline] fn add_to_glob_map(&mut self, directive: &ImportDirective<'_>, ident: Ident) { if directive.is_glob() { self.glob_map.entry(directive.id).or_default().insert(ident.name); } } /// A generic scope visitor. /// Visits scopes in order to resolve some identifier in them or perform other actions. /// If the callback returns `Some` result, we stop visiting scopes and return it. fn visit_scopes( &mut self, scope_set: ScopeSet, parent_scope: &ParentScope<'a>, ident: Ident, mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option, ) -> Option { // General principles: // 1. Not controlled (user-defined) names should have higher priority than controlled names // built into the language or standard library. This way we can add new names into the // language or standard library without breaking user code. // 2. "Closed set" below means new names cannot appear after the current resolution attempt. // Places to search (in order of decreasing priority): // (Type NS) // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet // (open set, not controlled). // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 3. Extern prelude (open, the open part is from macro expansions, not controlled). // 4. Tool modules (closed, controlled right now, but not in the future). // 5. Standard library prelude (de-facto closed, controlled). // 6. Language prelude (closed, controlled). // (Value NS) // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet // (open set, not controlled). // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 3. Standard library prelude (de-facto closed, controlled). // (Macro NS) // 1-3. Derive helpers (open, not controlled). All ambiguities with other names // are currently reported as errors. They should be higher in priority than preludes // and probably even names in modules according to the "general principles" above. They // also should be subject to restricted shadowing because are effectively produced by // derives (you need to resolve the derive first to add helpers into scope), but they // should be available before the derive is expanded for compatibility. // It's mess in general, so we are being conservative for now. // 1-3. `macro_rules` (open, not controlled), loop through legacy scopes. Have higher // priority than prelude macros, but create ambiguities with macros in modules. // 1-3. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). Have higher priority than prelude macros, but create // ambiguities with `macro_rules`. // 4. `macro_use` prelude (open, the open part is from macro expansions, not controlled). // 4a. User-defined prelude from macro-use // (open, the open part is from macro expansions, not controlled). // 4b. "Standard library prelude" part implemented through `macro-use` (closed, controlled). // 4c. Standard library prelude (de-facto closed, controlled). // 6. Language prelude: builtin attributes (closed, controlled). let rust_2015 = ident.span.rust_2015(); let (ns, macro_kind, is_absolute_path) = match scope_set { ScopeSet::All(ns, _) => (ns, None, false), ScopeSet::AbsolutePath(ns) => (ns, None, true), ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind), false), }; // Jump out of trait or enum modules, they do not act as scopes. let module = parent_scope.module.nearest_item_scope(); let mut scope = match ns { _ if is_absolute_path => Scope::CrateRoot, TypeNS | ValueNS => Scope::Module(module), MacroNS => Scope::DeriveHelpers(parent_scope.expansion), }; let mut ident = ident.modern(); let mut use_prelude = !module.no_implicit_prelude; loop { let visit = match scope { // Derive helpers are not in scope when resolving derives in the same container. Scope::DeriveHelpers(expn_id) => { !(expn_id == parent_scope.expansion && macro_kind == Some(MacroKind::Derive)) } Scope::DeriveHelpersCompat => true, Scope::MacroRules(..) => true, Scope::CrateRoot => true, Scope::Module(..) => true, Scope::RegisteredAttrs => use_prelude, Scope::MacroUsePrelude => use_prelude || rust_2015, Scope::BuiltinAttrs => true, Scope::ExternPrelude => use_prelude || is_absolute_path, Scope::ToolPrelude => use_prelude, Scope::StdLibPrelude => use_prelude || ns == MacroNS, Scope::BuiltinTypes => true, }; if visit { if let break_result @ Some(..) = visitor(self, scope, use_prelude, ident) { return break_result; } } scope = match scope { Scope::DeriveHelpers(expn_id) if expn_id != ExpnId::root() => { // Derive helpers are not visible to code generated by bang or derive macros. let expn_data = expn_id.expn_data(); match expn_data.kind { ExpnKind::Root | ExpnKind::Macro(MacroKind::Bang, _) | ExpnKind::Macro(MacroKind::Derive, _) => Scope::DeriveHelpersCompat, _ => Scope::DeriveHelpers(expn_data.parent), } } Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat, Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.legacy), Scope::MacroRules(legacy_scope) => match legacy_scope { LegacyScope::Binding(binding) => Scope::MacroRules(binding.parent_legacy_scope), LegacyScope::Invocation(invoc_id) => Scope::MacroRules( self.output_legacy_scopes .get(&invoc_id) .cloned() .unwrap_or(self.invocation_parent_scopes[&invoc_id].legacy), ), LegacyScope::Empty => Scope::Module(module), }, Scope::CrateRoot => match ns { TypeNS => { ident.span.adjust(ExpnId::root()); Scope::ExternPrelude } ValueNS | MacroNS => break, }, Scope::Module(module) => { use_prelude = !module.no_implicit_prelude; match self.hygienic_lexical_parent(module, &mut ident.span) { Some(parent_module) => Scope::Module(parent_module), None => { ident.span.adjust(ExpnId::root()); match ns { TypeNS => Scope::ExternPrelude, ValueNS => Scope::StdLibPrelude, MacroNS => Scope::RegisteredAttrs, } } } } Scope::RegisteredAttrs => Scope::MacroUsePrelude, Scope::MacroUsePrelude => Scope::StdLibPrelude, Scope::BuiltinAttrs => break, // nowhere else to search Scope::ExternPrelude if is_absolute_path => break, Scope::ExternPrelude => Scope::ToolPrelude, Scope::ToolPrelude => Scope::StdLibPrelude, Scope::StdLibPrelude => match ns { TypeNS => Scope::BuiltinTypes, ValueNS => break, // nowhere else to search MacroNS => Scope::BuiltinAttrs, }, Scope::BuiltinTypes => break, // nowhere else to search }; } None } /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope. /// More specifically, we proceed up the hierarchy of scopes and return the binding for /// `ident` in the first scope that defines it (or None if no scopes define it). /// /// A block's items are above its local variables in the scope hierarchy, regardless of where /// the items are defined in the block. For example, /// ```rust /// fn f() { /// g(); // Since there are no local variables in scope yet, this resolves to the item. /// let g = || {}; /// fn g() {} /// g(); // This resolves to the local variable `g` since it shadows the item. /// } /// ``` /// /// Invariant: This must only be called during main resolution, not during /// import resolution. fn resolve_ident_in_lexical_scope( &mut self, mut ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, record_used_id: Option, path_span: Span, ribs: &[Rib<'a>], ) -> Option> { assert!(ns == TypeNS || ns == ValueNS); if ident.name == kw::Invalid { return Some(LexicalScopeBinding::Res(Res::Err)); } let (general_span, modern_span) = if ident.name == kw::SelfUpper { // FIXME(jseyfried) improve `Self` hygiene let empty_span = ident.span.with_ctxt(SyntaxContext::root()); (empty_span, empty_span) } else if ns == TypeNS { let modern_span = ident.span.modern(); (modern_span, modern_span) } else { (ident.span.modern_and_legacy(), ident.span.modern()) }; ident.span = general_span; let modern_ident = Ident { span: modern_span, ..ident }; // Walk backwards up the ribs in scope. let record_used = record_used_id.is_some(); let mut module = self.graph_root; for i in (0..ribs.len()).rev() { debug!("walk rib\n{:?}", ribs[i].bindings); // Use the rib kind to determine whether we are resolving parameters // (modern hygiene) or local variables (legacy hygiene). let rib_ident = if ribs[i].kind.contains_params() { modern_ident } else { ident }; if let Some(res) = ribs[i].bindings.get(&rib_ident).cloned() { // The ident resolves to a type parameter or local variable. return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs( i, rib_ident, res, record_used, path_span, ribs, ))); } module = match ribs[i].kind { ModuleRibKind(module) => module, MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => { // If an invocation of this macro created `ident`, give up on `ident` // and switch to `ident`'s source from the macro definition. ident.span.remove_mark(); continue; } _ => continue, }; let item = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(module), ident, ns, parent_scope, record_used, path_span, ); if let Ok(binding) = item { // The ident resolves to an item. return Some(LexicalScopeBinding::Item(binding)); } match module.kind { ModuleKind::Block(..) => {} // We can see through blocks _ => break, } } ident = modern_ident; let mut poisoned = None; loop { let opt_module = if let Some(node_id) = record_used_id { self.hygienic_lexical_parent_with_compatibility_fallback( module, &mut ident.span, node_id, &mut poisoned, ) } else { self.hygienic_lexical_parent(module, &mut ident.span) }; module = unwrap_or!(opt_module, break); let adjusted_parent_scope = &ParentScope { module, ..*parent_scope }; let result = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(module), ident, ns, adjusted_parent_scope, record_used, path_span, ); match result { Ok(binding) => { if let Some(node_id) = poisoned { self.lint_buffer.buffer_lint_with_diagnostic( lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK, node_id, ident.span, &format!("cannot find {} `{}` in this scope", ns.descr(), ident), BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback(ident.span), ); } return Some(LexicalScopeBinding::Item(binding)); } Err(Determined) => continue, Err(Undetermined) => { span_bug!(ident.span, "undetermined resolution during main resolution pass") } } } if !module.no_implicit_prelude { ident.span.adjust(ExpnId::root()); if ns == TypeNS { if let Some(binding) = self.extern_prelude_get(ident, !record_used) { return Some(LexicalScopeBinding::Item(binding)); } if let Some(ident) = self.registered_tools.get(&ident) { let binding = (Res::ToolMod, ty::Visibility::Public, ident.span, ExpnId::root()) .to_name_binding(self.arenas); return Some(LexicalScopeBinding::Item(binding)); } } if let Some(prelude) = self.prelude { if let Ok(binding) = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(prelude), ident, ns, parent_scope, false, path_span, ) { return Some(LexicalScopeBinding::Item(binding)); } } } if ns == TypeNS { if let Some(prim_ty) = self.primitive_type_table.primitive_types.get(&ident.name) { let binding = (Res::PrimTy(*prim_ty), ty::Visibility::Public, DUMMY_SP, ExpnId::root()) .to_name_binding(self.arenas); return Some(LexicalScopeBinding::Item(binding)); } } None } fn hygienic_lexical_parent( &mut self, module: Module<'a>, span: &mut Span, ) -> Option> { if !module.expansion.outer_expn_is_descendant_of(span.ctxt()) { return Some(self.macro_def_scope(span.remove_mark())); } if let ModuleKind::Block(..) = module.kind { return Some(module.parent.unwrap().nearest_item_scope()); } None } fn hygienic_lexical_parent_with_compatibility_fallback( &mut self, module: Module<'a>, span: &mut Span, node_id: NodeId, poisoned: &mut Option, ) -> Option> { if let module @ Some(..) = self.hygienic_lexical_parent(module, span) { return module; } // We need to support the next case under a deprecation warning // ``` // struct MyStruct; // ---- begin: this comes from a proc macro derive // mod implementation_details { // // Note that `MyStruct` is not in scope here. // impl SomeTrait for MyStruct { ... } // } // ---- end // ``` // So we have to fall back to the module's parent during lexical resolution in this case. if let Some(parent) = module.parent { // Inner module is inside the macro, parent module is outside of the macro. if module.expansion != parent.expansion && module.expansion.is_descendant_of(parent.expansion) { // The macro is a proc macro derive if let Some(&def_id) = self.macro_defs.get(&module.expansion) { if let Some(ext) = self.get_macro_by_def_id(def_id) { if !ext.is_builtin && ext.macro_kind() == MacroKind::Derive { if parent.expansion.outer_expn_is_descendant_of(span.ctxt()) { *poisoned = Some(node_id); return module.parent; } } } } } } None } fn resolve_ident_in_module( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, record_used: bool, path_span: Span, ) -> Result<&'a NameBinding<'a>, Determinacy> { self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, record_used, path_span) .map_err(|(determinacy, _)| determinacy) } fn resolve_ident_in_module_ext( &mut self, module: ModuleOrUniformRoot<'a>, mut ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, record_used: bool, path_span: Span, ) -> Result<&'a NameBinding<'a>, (Determinacy, Weak)> { let tmp_parent_scope; let mut adjusted_parent_scope = parent_scope; match module { ModuleOrUniformRoot::Module(m) => { if let Some(def) = ident.span.modernize_and_adjust(m.expansion) { tmp_parent_scope = ParentScope { module: self.macro_def_scope(def), ..*parent_scope }; adjusted_parent_scope = &tmp_parent_scope; } } ModuleOrUniformRoot::ExternPrelude => { ident.span.modernize_and_adjust(ExpnId::root()); } ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => { // No adjustments } } let result = self.resolve_ident_in_module_unadjusted_ext( module, ident, ns, adjusted_parent_scope, false, record_used, path_span, ); result } fn resolve_crate_root(&mut self, ident: Ident) -> Module<'a> { 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 modern 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.modern_and_legacy(); let mut iter = ctxt.marks().into_iter().rev().peekable(); let mut result = None; // Find the last modern 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; } } // Then find the last legacy mark from the end if it exists. for (mark, transparency) in iter { if transparency == Transparency::SemiTransparent { result = Some(mark); } else { break; } } result } else { ctxt = ctxt.modern(); ctxt.adjust(ExpnId::root()) }; let module = match mark { Some(def) => self.macro_def_scope(def), None => return self.graph_root, }; self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id }) } fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> { let mut module = self.get_module(module.normal_ancestor_id); while module.span.ctxt().modern() != *ctxt { let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark())); module = self.get_module(parent.normal_ancestor_id); } module } fn resolve_path( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, record_used: bool, path_span: Span, crate_lint: CrateLint, ) -> PathResult<'a> { self.resolve_path_with_ribs( path, opt_ns, parent_scope, record_used, path_span, crate_lint, None, ) } fn resolve_path_with_ribs( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, record_used: bool, path_span: Span, crate_lint: CrateLint, ribs: Option<&PerNS>>>, ) -> PathResult<'a> { let mut module = None; let mut allow_super = true; let mut second_binding = None; debug!( "resolve_path(path={:?}, opt_ns={:?}, record_used={:?}, \ path_span={:?}, crate_lint={:?})", path, opt_ns, record_used, path_span, crate_lint, ); for (i, &Segment { ident, id }) in path.iter().enumerate() { debug!("resolve_path ident {} {:?} {:?}", i, ident, id); let record_segment_res = |this: &mut Self, res| { if record_used { if let Some(id) = id { if !this.partial_res_map.contains_key(&id) { assert!(id != ast::DUMMY_NODE_ID, "Trying to resolve dummy id"); this.record_partial_res(id, PartialRes::new(res)); } } } }; let is_last = i == path.len() - 1; let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS }; let name = ident.name; allow_super &= ns == TypeNS && (name == kw::SelfLower || name == kw::Super); if ns == TypeNS { if allow_super && name == kw::Super { let mut ctxt = ident.span.ctxt().modern(); let self_module = match i { 0 => Some(self.resolve_self(&mut ctxt, parent_scope.module)), _ => match module { Some(ModuleOrUniformRoot::Module(module)) => Some(module), _ => None, }, }; if let Some(self_module) = self_module { if let Some(parent) = self_module.parent { module = Some(ModuleOrUniformRoot::Module( self.resolve_self(&mut ctxt, parent), )); continue; } } let msg = "there are too many leading `super` keywords".to_string(); return PathResult::Failed { span: ident.span, label: msg, suggestion: None, is_error_from_last_segment: false, }; } if i == 0 { if name == kw::SelfLower { let mut ctxt = ident.span.ctxt().modern(); module = Some(ModuleOrUniformRoot::Module( self.resolve_self(&mut ctxt, parent_scope.module), )); continue; } if name == kw::PathRoot && ident.span.rust_2018() { module = Some(ModuleOrUniformRoot::ExternPrelude); continue; } if name == kw::PathRoot && ident.span.rust_2015() && self.session.rust_2018() { // `::a::b` from 2015 macro on 2018 global edition module = Some(ModuleOrUniformRoot::CrateRootAndExternPrelude); continue; } if name == kw::PathRoot || name == kw::Crate || name == kw::DollarCrate { // `::a::b`, `crate::a::b` or `$crate::a::b` module = Some(ModuleOrUniformRoot::Module(self.resolve_crate_root(ident))); continue; } } } // Report special messages for path segment keywords in wrong positions. if ident.is_path_segment_keyword() && i != 0 { let name_str = if name == kw::PathRoot { "crate root".to_string() } else { format!("`{}`", name) }; let label = if i == 1 && path[0].ident.name == kw::PathRoot { format!("global paths cannot start with {}", name_str) } else { format!("{} in paths can only be used in start position", name_str) }; return PathResult::Failed { span: ident.span, label, suggestion: None, is_error_from_last_segment: false, }; } let binding = if let Some(module) = module { self.resolve_ident_in_module( module, ident, ns, parent_scope, record_used, path_span, ) } else if ribs.is_none() || opt_ns.is_none() || opt_ns == Some(MacroNS) { let scopes = ScopeSet::All(ns, opt_ns.is_none()); self.early_resolve_ident_in_lexical_scope( ident, scopes, parent_scope, record_used, record_used, path_span, ) } else { let record_used_id = if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None }; match self.resolve_ident_in_lexical_scope( ident, ns, parent_scope, record_used_id, path_span, &ribs.unwrap()[ns], ) { // we found a locally-imported or available item/module Some(LexicalScopeBinding::Item(binding)) => Ok(binding), // we found a local variable or type param Some(LexicalScopeBinding::Res(res)) if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => { record_segment_res(self, res); return PathResult::NonModule(PartialRes::with_unresolved_segments( res, path.len() - 1, )); } _ => Err(Determinacy::determined(record_used)), } }; match binding { Ok(binding) => { if i == 1 { second_binding = Some(binding); } let res = binding.res(); let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(res); if let Some(next_module) = binding.module() { module = Some(ModuleOrUniformRoot::Module(next_module)); record_segment_res(self, res); } else if res == Res::ToolMod && i + 1 != path.len() { if binding.is_import() { self.session .struct_span_err( ident.span, "cannot use a tool module through an import", ) .span_note(binding.span, "the tool module imported here") .emit(); } let res = Res::NonMacroAttr(NonMacroAttrKind::Tool); return PathResult::NonModule(PartialRes::new(res)); } else if res == Res::Err { return PathResult::NonModule(PartialRes::new(Res::Err)); } else if opt_ns.is_some() && (is_last || maybe_assoc) { self.lint_if_path_starts_with_module( crate_lint, path, path_span, second_binding, ); return PathResult::NonModule(PartialRes::with_unresolved_segments( res, path.len() - i - 1, )); } else { let label = format!( "`{}` is {} {}, not a module", ident, res.article(), res.descr(), ); return PathResult::Failed { span: ident.span, label, suggestion: None, is_error_from_last_segment: is_last, }; } } Err(Undetermined) => return PathResult::Indeterminate, Err(Determined) => { if let Some(ModuleOrUniformRoot::Module(module)) = module { if opt_ns.is_some() && !module.is_normal() { return PathResult::NonModule(PartialRes::with_unresolved_segments( module.res().unwrap(), path.len() - i, )); } } let module_res = match module { Some(ModuleOrUniformRoot::Module(module)) => module.res(), _ => None, }; let (label, suggestion) = if module_res == self.graph_root.res() { let is_mod = |res| match res { Res::Def(DefKind::Mod, _) => true, _ => false, }; let mut candidates = self.lookup_import_candidates(ident, TypeNS, is_mod); candidates.sort_by_cached_key(|c| { (c.path.segments.len(), pprust::path_to_string(&c.path)) }); if let Some(candidate) = candidates.get(0) { ( String::from("unresolved import"), Some(( vec![(ident.span, pprust::path_to_string(&candidate.path))], String::from("a similar path exists"), Applicability::MaybeIncorrect, )), ) } else if !ident.is_reserved() { (format!("maybe a missing crate `{}`?", ident), None) } else { // the parser will already have complained about the keyword being used return PathResult::NonModule(PartialRes::new(Res::Err)); } } else if i == 0 { (format!("use of undeclared type or module `{}`", ident), None) } else { (format!("could not find `{}` in `{}`", ident, path[i - 1].ident), None) }; return PathResult::Failed { span: ident.span, label, suggestion, is_error_from_last_segment: is_last, }; } } } self.lint_if_path_starts_with_module(crate_lint, path, path_span, second_binding); PathResult::Module(match module { Some(module) => module, None if path.is_empty() => ModuleOrUniformRoot::CurrentScope, _ => span_bug!(path_span, "resolve_path: non-empty path `{:?}` has no module", path), }) } fn lint_if_path_starts_with_module( &mut self, crate_lint: CrateLint, path: &[Segment], path_span: Span, second_binding: Option<&NameBinding<'_>>, ) { let (diag_id, diag_span) = match crate_lint { CrateLint::No => return, CrateLint::SimplePath(id) => (id, path_span), CrateLint::UsePath { root_id, root_span } => (root_id, root_span), CrateLint::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 { directive: d, .. } = binding.kind { // Careful: we still want to rewrite paths from // renamed extern crates. if let ImportDirectiveSubclass::ExternCrate { source: None, .. } = d.subclass { 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, ); } // Validate a local resolution (from ribs). fn validate_res_from_ribs( &mut self, rib_index: usize, rib_ident: Ident, res: Res, record_used: bool, span: Span, all_ribs: &[Rib<'a>], ) -> Res { debug!("validate_res_from_ribs({:?})", res); let ribs = &all_ribs[rib_index + 1..]; // An invalid forward use of a type parameter from a previous default. if let ForwardTyParamBanRibKind = all_ribs[rib_index].kind { if record_used { let res_error = if rib_ident.name == kw::SelfUpper { ResolutionError::SelfInTyParamDefault } else { ResolutionError::ForwardDeclaredTyParam }; self.report_error(span, res_error); } assert_eq!(res, Res::Err); return Res::Err; } match res { Res::Local(_) => { use ResolutionError::*; let mut res_err = None; for rib in ribs { match rib.kind { NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind => { // Nothing to do. Continue. } ItemRibKind(_) | FnItemRibKind | AssocItemRibKind => { // This was an attempt to access an upvar inside a // named function item. This is not allowed, so we // report an error. if record_used { // We don't immediately trigger a resolve error, because // we want certain other resolution errors (namely those // emitted for `ConstantItemRibKind` below) to take // precedence. res_err = Some(CannotCaptureDynamicEnvironmentInFnItem); } } ConstantItemRibKind => { // Still doesn't deal with upvars if record_used { self.report_error(span, AttemptToUseNonConstantValueInConstant); } return Res::Err; } } } if let Some(res_err) = res_err { self.report_error(span, res_err); return Res::Err; } } Res::Def(DefKind::TyParam, _) | Res::SelfTy(..) => { for rib in ribs { let has_generic_params = match rib.kind { NormalRibKind | AssocItemRibKind | ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind | ConstantItemRibKind => { // Nothing to do. Continue. continue; } // This was an attempt to use a type parameter outside its scope. ItemRibKind(has_generic_params) => has_generic_params, FnItemRibKind => HasGenericParams::Yes, }; if record_used { self.report_error( span, ResolutionError::GenericParamsFromOuterFunction( res, has_generic_params, ), ); } return Res::Err; } } Res::Def(DefKind::ConstParam, _) => { let mut ribs = ribs.iter().peekable(); if let Some(Rib { kind: FnItemRibKind, .. }) = ribs.peek() { // When declaring const parameters inside function signatures, the first rib // is always a `FnItemRibKind`. In this case, we can skip it, to avoid it // (spuriously) conflicting with the const param. ribs.next(); } for rib in ribs { let has_generic_params = match rib.kind { ItemRibKind(has_generic_params) => has_generic_params, FnItemRibKind => HasGenericParams::Yes, _ => continue, }; // This was an attempt to use a const parameter outside its scope. if record_used { self.report_error( span, ResolutionError::GenericParamsFromOuterFunction( res, has_generic_params, ), ); } return Res::Err; } } _ => {} } res } 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 is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool { vis.is_accessible_from(module.normal_ancestor_id, 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(PtrKey(binding), module) { if !ptr::eq(module, old_module) { span_bug!(binding.span, "parent module is reset for binding"); } } } fn disambiguate_legacy_vs_modern( &self, legacy: &'a NameBinding<'a>, modern: &'a NameBinding<'a>, ) -> bool { // Some non-controversial subset of ambiguities "modern 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(&PtrKey(legacy)), self.binding_parent_modules.get(&PtrKey(modern)), ) { (Some(legacy), Some(modern)) => { legacy.normal_ancestor_id == modern.normal_ancestor_id && modern.is_ancestor_of(legacy) } _ => 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, node_id, better, suggestion } in self.use_injections.drain(..) { let (span, found_use) = UsePlacementFinder::check(krate, node_id); if !candidates.is_empty() { diagnostics::show_candidates(&mut err, span, &candidates, better, found_use); } 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(DefKind::Mod, _, _) => "module", ModuleKind::Def(DefKind::Trait, _, _) => "trait", ModuleKind::Block(..) => "block", _ => "enum", }; 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().def_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().def_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 directive = 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 { directive: new, .. }, Import { directive: 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 { directive, .. }, other) if !new_binding.span.is_dummy() => { Some((directive, new_binding.span, other.is_import())) } (other, Import { directive, .. }) if !old_binding.span.is_dummy() => { Some((directive, 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(|entry| entry.introduced_by_item).unwrap_or(true); // 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 a item. let should_remove_import = duplicate && !has_dummy_span && ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item); match directive { Some((directive, span, true)) if should_remove_import && directive.is_nested() => { self.add_suggestion_for_duplicate_nested_use(&mut err, directive, span) } Some((directive, _, true)) if should_remove_import && !directive.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( directive.use_span_with_attributes, "remove unnecessary import", String::new(), Applicability::MaybeIncorrect, ); } Some((directive, span, _)) => { self.add_suggestion_for_rename_of_use(&mut err, name, directive, 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. /// /// ```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 DiagnosticBuilder<'_>, name: Name, directive: &ImportDirective<'_>, 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 directive.subclass { ImportDirectiveSubclass::SingleImport { type_ns_only: true, .. } => { suggestion = Some(format!("self as {}", suggested_name)) } ImportDirectiveSubclass::SingleImport { 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 { "" } )) } } } } ImportDirectiveSubclass::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 a 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 directive provided is a nested import - 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 DiagnosticBuilder<'_>, directive: &ImportDirective<'_>, binding_span: Span, ) { assert!(directive.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 `directive.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 `directive.use_span` is `issue_52891::{d, e, a};`. let (found_closing_brace, span) = find_span_of_binding_until_next_binding(self.session, binding_span, directive.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 a // `issue_52891::{self}` case. err.span_suggestion( directive.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, speculative: 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.modern()).cloned().and_then(|entry| { if let Some(binding) = entry.extern_crate_item { if !speculative && entry.introduced_by_item { self.record_use(ident, TypeNS, binding, false); } Some(binding) } else { let crate_id = if !speculative { self.crate_loader.process_path_extern(ident.name, ident.span) } else if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name, ident.span) { crate_id } else { return None; }; let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX }); Some( (crate_root, ty::Visibility::Public, DUMMY_SP, ExpnId::root()) .to_name_binding(self.arenas), ) } }) } /// Rustdoc uses this to resolve things in a recoverable way. `ResolutionError<'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. // FIXME(Manishearth): intra-doc links won't get warned of epoch changes. pub fn resolve_str_path_error( &mut self, span: Span, path_str: &str, ns: Namespace, module_id: NodeId, ) -> Result<(ast::Path, Res), ()> { let path = if path_str.starts_with("::") { ast::Path { span, segments: iter::once(Ident::with_dummy_span(kw::PathRoot)) .chain({ path_str.split("::").skip(1).map(Ident::from_str) }) .map(|i| self.new_ast_path_segment(i)) .collect(), } } else { ast::Path { span, segments: path_str .split("::") .map(Ident::from_str) .map(|i| self.new_ast_path_segment(i)) .collect(), } }; let module = self.block_map.get(&module_id).copied().unwrap_or_else(|| { let def_id = self.definitions.local_def_id(module_id); self.module_map.get(&def_id).copied().unwrap_or(self.graph_root) }); let parent_scope = &ParentScope::module(module); let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?; Ok((path, res)) } // Resolve a path passed from rustdoc or HIR lowering. fn resolve_ast_path( &mut self, path: &ast::Path, ns: Namespace, parent_scope: &ParentScope<'a>, ) -> Result)> { match self.resolve_path( &Segment::from_path(path), Some(ns), parent_scope, true, path.span, CrateLint::No, ) { PathResult::Module(ModuleOrUniformRoot::Module(module)) => Ok(module.res().unwrap()), PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 => { Ok(path_res.base_res()) } PathResult::NonModule(..) => Err(( path.span, ResolutionError::FailedToResolve { label: String::from("type-relative paths are not supported in this context"), suggestion: None, }, )), PathResult::Module(..) | PathResult::Indeterminate => unreachable!(), PathResult::Failed { span, label, suggestion, .. } => { Err((span, ResolutionError::FailedToResolve { label, suggestion })) } } } fn new_ast_path_segment(&mut self, ident: Ident) -> ast::PathSegment { let mut seg = ast::PathSegment::from_ident(ident); seg.id = self.next_node_id(); seg } // For rustdoc. pub fn graph_root(&self) -> Module<'a> { self.graph_root } // For rustdoc. pub fn all_macros(&self) -> &FxHashMap { &self.all_macros } } fn names_to_string(names: &[Name]) -> 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(Name::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 CrateLint { /// 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), /// 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 }, /// 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 }, } impl CrateLint { fn node_id(&self) -> Option { match *self { CrateLint::No => None, CrateLint::SimplePath(id) | CrateLint::UsePath { root_id: id, .. } | CrateLint::QPathTrait { qpath_id: id, .. } => Some(id), } } } pub fn provide(providers: &mut Providers<'_>) { lifetimes::provide(providers); }