diff options
Diffstat (limited to 'compiler/rustc_resolve/src/lib.rs')
| -rw-r--r-- | compiler/rustc_resolve/src/lib.rs | 3328 |
1 files changed, 3328 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs new file mode 100644 index 00000000000..5892edf7652 --- /dev/null +++ b/compiler/rustc_resolve/src/lib.rs @@ -0,0 +1,3328 @@ +// 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 `librustc_typeck`. + +#![doc(html_root_url = "https://doc.rust-lang.org/nightly/")] +#![feature(bool_to_option)] +#![feature(crate_visibility_modifier)] +#![feature(nll)] +#![feature(or_patterns)] +#![recursion_limit = "256"] + +pub use rustc_hir::def::{Namespace, PerNS}; + +use Determinacy::*; + +use rustc_arena::TypedArena; +use rustc_ast::node_id::NodeMap; +use rustc_ast::unwrap_or; +use rustc_ast::visit::{self, Visitor}; +use rustc_ast::{self as ast, FloatTy, IntTy, NodeId, UintTy}; +use rustc_ast::{Crate, CRATE_NODE_ID}; +use rustc_ast::{ItemKind, Path}; +use rustc_ast_lowering::ResolverAstLowering; +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, LocalDefId, CRATE_DEF_INDEX}; +use rustc_hir::definitions::{DefKey, DefPathData, Definitions}; +use rustc_hir::PrimTy::{self, Bool, Char, Float, Int, Str, Uint}; +use rustc_hir::TraitCandidate; +use rustc_index::vec::IndexVec; +use rustc_metadata::creader::{CStore, CrateLoader}; +use rustc_middle::hir::exports::ExportMap; +use rustc_middle::middle::cstore::{CrateStore, MetadataLoaderDyn}; +use rustc_middle::ty::query::Providers; +use rustc_middle::ty::{self, DefIdTree, ResolverOutputs}; +use rustc_middle::{bug, span_bug}; +use rustc_session::lint; +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, 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, iter, 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, Rib, RibKind::*}; +use macros::{MacroRulesBinding, MacroRulesScope}; + +type Res = def::Res<NodeId>; + +mod build_reduced_graph; +mod check_unused; +mod def_collector; +mod diagnostics; +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(ExpnId), + DeriveHelpersCompat, + MacroRules(MacroRulesScope<'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, + macro_rules: MacroRulesScope<'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(), + macro_rules: MacroRulesScope::Empty, + derives: &[], + } + } +} + +#[derive(Eq)] +struct BindingError { + name: Symbol, + origin: BTreeSet<Span>, + target: BTreeSet<Span>, + could_be_path: bool, +} + +impl PartialOrd for BindingError { + fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> { + 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(Symbol, &'a str), + /// Error E0437: type is not a member of trait. + TypeNotMemberOfTrait(Symbol, &'a str), + /// Error E0438: const is not a member of trait. + ConstNotMemberOfTrait(Symbol, &'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(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<LabelSuggestion> }, + /// 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<Suggestion> }, + /// 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(&'static str, Symbol, &'a NameBinding<'a>), + /// Error E0128: type parameters with a default cannot use forward-declared identifiers. + ForwardDeclaredTyParam, // FIXME(const_generics:defaults) + /// ERROR E0770: the type of const parameters must not depend on other generic parameters. + ParamInTyOfConstParam(Symbol), + /// constant values inside of type parameter defaults must not depend on generic parameters. + ParamInAnonConstInTyDefault(Symbol), + /// generic parameters must not be used inside of non trivial constant values. + /// + /// This error is only emitted when using `min_const_generics`. + ParamInNonTrivialAnonConst(Symbol), + /// Error E0735: type parameters with a default cannot use `Self` + SelfInTyParamDefault, + /// Error E0767: use of unreachable label + UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> }, +} + +enum VisResolutionError<'a> { + Relative2018(Span, &'a ast::Path), + AncestorOnly(Span), + FailedToResolve(Span, String, Option<Suggestion>), + 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<NodeId>, + /// 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<Segment> { + 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::<Vec<_>>()) + } +} + +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() } + } +} + +struct UsePlacementFinder { + target_module: NodeId, + span: Option<Span>, + found_use: bool, +} + +impl UsePlacementFinder { + fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, 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 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<Suggestion>, + 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, Symbol), +} + +impl ModuleKind { + /// Get name of the module. + pub fn name(&self) -> Option<Symbol> { + 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, aways 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<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>; + +/// One node in the tree of modules. +pub struct ModuleData<'a> { + parent: Option<Module<'a>>, + 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<bool>, + + // Macro invocations that can expand into items in this module. + unexpanded_invocations: RefCell<FxHashSet<ExpnId>>, + + no_implicit_prelude: bool, + + glob_importers: RefCell<Vec<&'a Import<'a>>>, + globs: RefCell<Vec<&'a Import<'a>>>, + + // Used to memoize the traits in this module for faster searches through all traits in scope. + traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>, + + /// 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<Module<'a>>, + 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<R, F>(&'a self, resolver: &mut R, mut f: F) + where + R: AsMut<Resolver<'a>>, + 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<R>(&'a self, resolver: &mut R) + where + R: AsMut<Resolver<'a>>, + { + 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; + } + match binding.res() { + Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => { + collected_traits.push((name, binding)) + } + _ => (), + } + }); + *traits = Some(collected_traits.into_boxed_slice()); + } + } + + fn res(&self) -> Option<Res> { + match self.kind { + ModuleKind::Def(kind, def_id, _) => Some(Res::Def(kind, def_id)), + _ => None, + } + } + + fn def_id(&self) -> Option<DefId> { + 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 | 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>, import: &'a Import<'a>, used: Cell<bool> }, +} + +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>, + /// Candidates which user could `use` to access the missing type. + candidates: Vec<ImportSuggestion>, + /// 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 => "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::MacroRulesVsModularized => { + "`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<Module<'a>> { + 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(), + _ => self.is_variant(), + } + } + + // 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 | DefKind::Ctor(CtorOf::Variant, ..), _), + _, + ) => true, + _ => 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 { + match self.kind { + NameBindingKind::Import { .. } => true, + _ => false, + } + } + + fn is_glob_import(&self) -> bool { + match self.kind { + NameBindingKind::Import { import, .. } => import.is_glob(), + _ => false, + } + } + + fn is_importable(&self) -> bool { + match self.res() { + Res::Def(DefKind::AssocConst | DefKind::AssocFn | 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<MacroKind> { + 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<Symbol, PrimTy>, +} + +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<Module<'a>>, + extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'a>>, + + /// N.B., this is used only for better diagnostics, not name resolution itself. + has_self: FxHashSet<DefId>, + + /// Names of fields of an item `DefId` accessible with dot syntax. + /// Used for hints during error reporting. + field_names: FxHashMap<DefId, Vec<Spanned<Symbol>>>, + + /// All imports known to succeed or fail. + determined_imports: Vec<&'a Import<'a>>, + + /// All non-determined imports. + indeterminate_imports: Vec<&'a Import<'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. + unusable_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<PartialRes>, + /// Resolutions for import nodes, which have multiple resolutions in different namespaces. + import_res_map: NodeMap<PerNS<Option<Res>>>, + /// Resolutions for labels (node IDs of their corresponding blocks or loops). + label_res_map: NodeMap<NodeId>, + + /// `CrateNum` resolutions of `extern crate` items. + extern_crate_map: FxHashMap<LocalDefId, CrateNum>, + export_map: ExportMap<LocalDefId>, + trait_map: NodeMap<Vec<TraitCandidate>>, + + /// 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<Module<'a>>, + /// 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<LocalDefId, Module<'a>>, + extern_module_map: FxHashMap<DefId, Module<'a>>, + binding_parent_modules: FxHashMap<PtrKey<'a, NameBinding<'a>>, Module<'a>>, + underscore_disambiguator: u32, + + /// Maps glob imports to the names of items actually imported. + glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>, + + used_imports: FxHashSet<(NodeId, Namespace)>, + maybe_unused_trait_imports: FxHashSet<LocalDefId>, + maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, + + /// Privacy errors are delayed until the end in order to deduplicate them. + privacy_errors: Vec<PrivacyError<'a>>, + /// Ambiguity errors are delayed for deduplication. + ambiguity_errors: Vec<AmbiguityError<'a>>, + /// `use` injections are delayed for better placement and deduplication. + use_injections: Vec<UseError<'a>>, + /// 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<Ident>, + builtin_macros: FxHashMap<Symbol, SyntaxExtension>, + registered_attrs: FxHashSet<Ident>, + registered_tools: FxHashSet<Ident>, + macro_use_prelude: FxHashMap<Symbol, &'a NameBinding<'a>>, + all_macros: FxHashMap<Symbol, Res>, + macro_map: FxHashMap<DefId, Lrc<SyntaxExtension>>, + dummy_ext_bang: Lrc<SyntaxExtension>, + dummy_ext_derive: Lrc<SyntaxExtension>, + non_macro_attrs: [Lrc<SyntaxExtension>; 2], + local_macro_def_scopes: FxHashMap<LocalDefId, Module<'a>>, + ast_transform_scopes: FxHashMap<ExpnId, Module<'a>>, + unused_macros: FxHashMap<LocalDefId, (NodeId, Span)>, + proc_macro_stubs: FxHashSet<LocalDefId>, + /// 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<Segment>, Span, MacroKind, ParentScope<'a>, Option<Res>)>, + 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<ExpnId>, + /// 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<ExpnId, ParentScope<'a>>, + /// `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<ExpnId, MacroRulesScope<'a>>, + /// Helper attributes that are in scope for the given expansion. + helper_attrs: FxHashMap<ExpnId, Vec<Ident>>, + + /// Avoid duplicated errors for "name already defined". + name_already_seen: FxHashMap<Symbol, Span>, + + 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. + struct_constructors: DefIdMap<(Res, ty::Visibility)>, + + /// Features enabled for this crate. + active_features: FxHashSet<Symbol>, + + /// Stores enum visibilities to properly build a reduced graph + /// when visiting the correspondent variants. + variant_vis: DefIdMap<ty::Visibility>, + + lint_buffer: LintBuffer, + + next_node_id: NodeId, + + def_id_to_span: IndexVec<LocalDefId, Span>, + + node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>, + def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>, + + /// Indices of unnamed struct or variant fields with unresolved attributes. + placeholder_field_indices: FxHashMap<NodeId, usize>, + /// 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. + invocation_parents: FxHashMap<ExpnId, LocalDefId>, + + next_disambiguator: FxHashMap<(LocalDefId, DefPathData), u32>, +} + +/// Nothing really interesting here; it just provides memory for the rest of the crate. +#[derive(Default)] +pub struct ResolverArenas<'a> { + modules: TypedArena<ModuleData<'a>>, + local_modules: RefCell<Vec<Module<'a>>>, + name_bindings: TypedArena<NameBinding<'a>>, + imports: TypedArena<Import<'a>>, + name_resolutions: TypedArena<RefCell<NameResolution<'a>>>, + macro_rules_bindings: TypedArena<MacroRulesBinding<'a>>, + ast_paths: TypedArena<ast::Path>, +} + +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<Module<'a>>> { + 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(&'a self, import: Import<'a>) -> &'a Import<'_> { + self.imports.alloc(import) + } + fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> { + self.name_resolutions.alloc(Default::default()) + } + fn alloc_macro_rules_binding( + &'a self, + binding: MacroRulesBinding<'a>, + ) -> &'a MacroRulesBinding<'a> { + self.macro_rules_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<Resolver<'a>> 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<DefId> { + 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(&mut self, id: DefId) -> DefKey { + if let Some(id) = id.as_local() { + self.definitions().def_key(id) + } 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 get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> { + self.partial_res_map.get(&id).cloned() + } + + fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res>> { + self.import_res_map.get(&id).cloned().unwrap_or_default() + } + + fn get_label_res(&mut self, id: NodeId) -> Option<NodeId> { + 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() + } + + fn trait_map(&self) -> &NodeMap<Vec<TraitCandidate>> { + &self.trait_map + } + + fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> { + 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)) + } + + /// 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]), + ); + + // Find the next free disambiguator for this key. + let next_disambiguator = &mut self.next_disambiguator; + let next_disambiguator = |parent, data| { + let next_disamb = next_disambiguator.entry((parent, data)).or_insert(0); + let disambiguator = *next_disamb; + *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow"); + disambiguator + }; + + let def_id = self.definitions.create_def(parent, data, expn_id, next_disambiguator); + + assert_eq!(self.def_id_to_span.push(span), def_id); + + // 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 + } +} + +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: session.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(LocalDefId { local_def_index: CRATE_DEF_INDEX }, graph_root); + + let definitions = Definitions::new(crate_name, session.local_crate_disambiguator()); + let root = definitions.get_root_def(); + + let mut def_id_to_span = IndexVec::default(); + assert_eq!(def_id_to_span.push(rustc_span::DUMMY_SP), root); + 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(ExpnId::root(), root); + + let mut extern_prelude: FxHashMap<Ident, ExternPreludeEntry<'_>> = 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()); + 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 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, + unusable_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_macro_rules_scopes: Default::default(), + helper_attrs: 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(), + variant_vis: Default::default(), + lint_buffer: LintBuffer::default(), + next_node_id: NodeId::from_u32(1), + def_id_to_span, + node_id_to_def_id, + def_id_to_node_id, + placeholder_field_indices: Default::default(), + invocation_parents, + next_disambiguator: Default::default(), + } + } + + 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 { + let definitions = self.definitions; + let extern_crate_map = self.extern_crate_map; + let export_map = self.export_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; + ResolverOutputs { + definitions: definitions, + cstore: Box::new(self.crate_loader.into_cstore()), + extern_crate_map, + export_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(), + } + } + + 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(), + 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<SyntaxExtension> { + self.non_macro_attrs[mark_used as usize].clone() + } + + fn dummy_ext(&self, macro_kind: MacroKind) -> Lrc<SyntaxExtension> { + 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<F: FnMut(&mut Self, Namespace)>(&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 ctxt.outer_expn().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) { + 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 get_traits_in_module_containing_item( + &mut self, + ident: Ident, + ns: Namespace, + module: Module<'a>, + found_traits: &mut Vec<TraitCandidate>, + parent_scope: &ParentScope<'a>, + ) { + assert!(ns == TypeNS || ns == ValueNS); + module.ensure_traits(self); + let traits = module.traits.borrow(); + + for &(trait_name, binding) in traits.as_ref().unwrap().iter() { + // Traits have pseudo-modules that can be used to search for the given ident. + if let Some(module) = binding.module() { + let mut ident = ident; + if ident.span.glob_adjust(module.expansion, binding.span).is_none() { + continue; + } + if self + .resolve_ident_in_module_unadjusted( + ModuleOrUniformRoot::Module(module), + ident, + ns, + parent_scope, + false, + module.span, + ) + .is_ok() + { + let import_ids = self.find_transitive_imports(&binding.kind, trait_name); + let trait_def_id = module.def_id().unwrap(); + found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids }); + } + } else if let Res::Def(DefKind::TraitAlias, _) = binding.res() { + // For now, just treat all trait aliases as possible candidates, since we don't + // know if the ident is somewhere in the transitive bounds. + let import_ids = self.find_transitive_imports(&binding.kind, trait_name); + let trait_def_id = binding.res().def_id(); + found_traits.push(TraitCandidate { def_id: trait_def_id, import_ids }); + } else { + bug!("candidate is not trait or trait alias?") + } + } + } + + 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_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.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<NameResolution<'a>> { + *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 { 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, ns)); + self.add_to_glob_map(&import, ident); + self.record_use(ident, ns, 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); + } + } + + /// 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<T>( + &mut self, + scope_set: ScopeSet, + parent_scope: &ParentScope<'a>, + ident: Ident, + mut visitor: impl FnMut(&mut Self, Scope<'a>, /*use_prelude*/ bool, Ident) -> Option<T>, + ) -> Option<T> { + // 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 `macro_rules` 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.normalize_to_macros_2_0(); + 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 | MacroKind::Derive, _) => { + Scope::DeriveHelpersCompat + } + _ => Scope::DeriveHelpers(expn_data.parent), + } + } + Scope::DeriveHelpers(..) => Scope::DeriveHelpersCompat, + Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules), + Scope::MacroRules(macro_rules_scope) => match macro_rules_scope { + MacroRulesScope::Binding(binding) => { + Scope::MacroRules(binding.parent_macro_rules_scope) + } + MacroRulesScope::Invocation(invoc_id) => Scope::MacroRules( + self.output_macro_rules_scopes + .get(&invoc_id) + .cloned() + .unwrap_or(self.invocation_parent_scopes[&invoc_id].macro_rules), + ), + MacroRulesScope::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<NodeId>, + path_span: Span, + ribs: &[Rib<'a>], + ) -> Option<LexicalScopeBinding<'a>> { + assert!(ns == TypeNS || ns == ValueNS); + if ident.name == kw::Invalid { + return Some(LexicalScopeBinding::Res(Res::Err)); + } + let (general_span, normalized_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 normalized_span = ident.span.normalize_to_macros_2_0(); + (normalized_span, normalized_span) + } else { + (ident.span.normalize_to_macro_rules(), ident.span.normalize_to_macros_2_0()) + }; + ident.span = general_span; + let normalized_ident = Ident { span: normalized_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 + // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene). + let rib_ident = if ribs[i].kind.contains_params() { normalized_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 = normalized_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<Module<'a>> { + 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<NodeId>, + ) -> Option<Module<'a>> { + 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) = module.expansion.expn_data().macro_def_id { + 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.normalize_to_macros_2_0_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.normalize_to_macros_2_0_and_adjust(ExpnId::root()); + } + ModuleOrUniformRoot::CrateRootAndExternPrelude | ModuleOrUniformRoot::CurrentScope => { + // No adjustments + } + } + self.resolve_ident_in_module_unadjusted_ext( + module, + ident, + ns, + adjusted_parent_scope, + false, + record_used, + path_span, + ) + } + + 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::<Vec<_>>() + ); + 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.macro_def_scope(def), + None => { + debug!( + "resolve_crate_root({:?}): found no mark (ident.span = {:?})", + ident, ident.span + ); + return self.graph_root; + } + }; + let module = self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_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.get_module(module.normal_ancestor_id); + while module.span.ctxt().normalize_to_macros_2_0() != *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<Namespace>, // `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<Namespace>, // `None` indicates a module path in import + parent_scope: &ParentScope<'a>, + record_used: bool, + path_span: Span, + crate_lint: CrateLint, + ribs: Option<&PerNS<Vec<Rib<'a>>>>, + ) -> 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, has_generic_args: _ }) 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().normalize_to_macros_2_0(); + 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().normalize_to_macros_2_0(); + 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, + }; + } + + enum FindBindingResult<'a> { + Binding(Result<&'a NameBinding<'a>, Determinacy>), + PathResult(PathResult<'a>), + } + let find_binding_in_ns = |this: &mut Self, ns| { + let binding = if let Some(module) = module { + this.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()); + this.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 this.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(this, res); + return FindBindingResult::PathResult(PathResult::NonModule( + PartialRes::with_unresolved_segments(res, path.len() - 1), + )); + } + _ => Err(Determinacy::determined(record_used)), + } + }; + FindBindingResult::Binding(binding) + }; + let binding = match find_binding_in_ns(self, ns) { + FindBindingResult::PathResult(x) => return x, + FindBindingResult::Binding(binding) => binding, + }; + 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, + }; + // Don't look up import candidates if this is a speculative resolve + let mut candidates = if record_used { + self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod) + } else { + Vec::new() + }; + 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 { + (format!("maybe a missing crate `{}`?", ident), None) + } + } else if i == 0 { + (format!("use of undeclared type or module `{}`", ident), None) + } else { + let mut msg = + format!("could not find `{}` in `{}`", ident, path[i - 1].ident); + if ns == TypeNS || ns == ValueNS { + let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS }; + if let FindBindingResult::Binding(Ok(binding)) = + find_binding_in_ns(self, ns_to_try) + { + let mut found = |what| { + msg = format!( + "expected {}, found {} `{}` in `{}`", + ns.descr(), + what, + ident, + path[i - 1].ident + ) + }; + if binding.module().is_some() { + found("module") + } else { + match binding.res() { + def::Res::<NodeId>::Def(kind, id) => found(kind.descr(id)), + _ => found(ns_to_try.descr()), + } + } + }; + } + (msg, 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 { 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, + ); + } + + // 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 + | ClosureOrAsyncRibKind + | 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; + } + ConstParamTyRibKind => { + if record_used { + self.report_error(span, ParamInTyOfConstParam(rib_ident.name)); + } + 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(..) => { + let mut in_ty_param_default = false; + for rib in ribs { + let has_generic_params = match rib.kind { + NormalRibKind + | ClosureOrAsyncRibKind + | AssocItemRibKind + | ModuleRibKind(..) + | MacroDefinition(..) => { + // Nothing to do. Continue. + continue; + } + + // We only forbid constant items if we are inside of type defaults, + // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>` + ForwardTyParamBanRibKind => { + in_ty_param_default = true; + continue; + } + ConstantItemRibKind(trivial) => { + // HACK(min_const_generics): We currently only allow `N` or `{ N }`. + if !trivial && self.session.features_untracked().min_const_generics { + if record_used { + self.report_error( + span, + ResolutionError::ParamInNonTrivialAnonConst(rib_ident.name), + ); + } + return Res::Err; + } + + if in_ty_param_default { + if record_used { + self.report_error( + span, + ResolutionError::ParamInAnonConstInTyDefault( + rib_ident.name, + ), + ); + } + return Res::Err; + } else { + continue; + } + } + + // This was an attempt to use a type parameter outside its scope. + ItemRibKind(has_generic_params) => has_generic_params, + FnItemRibKind => HasGenericParams::Yes, + ConstParamTyRibKind => { + if record_used { + self.report_error( + span, + ResolutionError::ParamInTyOfConstParam(rib_ident.name), + ); + } + return Res::Err; + } + }; + + 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(); + } + + let mut in_ty_param_default = false; + for rib in ribs { + let has_generic_params = match rib.kind { + NormalRibKind + | ClosureOrAsyncRibKind + | AssocItemRibKind + | ModuleRibKind(..) + | MacroDefinition(..) => continue, + + // We only forbid constant items if we are inside of type defaults, + // for example `struct Foo<T, U = [u8; std::mem::size_of::<T>()]>` + ForwardTyParamBanRibKind => { + in_ty_param_default = true; + continue; + } + ConstantItemRibKind(trivial) => { + // HACK(min_const_generics): We currently only allow `N` or `{ N }`. + if !trivial && self.session.features_untracked().min_const_generics { + if record_used { + self.report_error( + span, + ResolutionError::ParamInNonTrivialAnonConst(rib_ident.name), + ); + } + return Res::Err; + } + + if in_ty_param_default { + if record_used { + self.report_error( + span, + ResolutionError::ParamInAnonConstInTyDefault( + rib_ident.name, + ), + ); + } + return Res::Err; + } else { + continue; + } + } + + ItemRibKind(has_generic_params) => has_generic_params, + FnItemRibKind => HasGenericParams::Yes, + ConstParamTyRibKind => { + if record_used { + self.report_error( + span, + ResolutionError::ParamInTyOfConstParam(rib_ident.name), + ); + } + return Res::Err; + } + }; + + // 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_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(&PtrKey(macro_rules)), + self.binding_parent_modules.get(&PtrKey(modularized)), + ) { + (Some(macro_rules), Some(modularized)) => { + macro_rules.normal_ancestor_id == modularized.normal_ancestor_id + && 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(&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().unwrap()), + 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(|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 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 DiagnosticBuilder<'_>, + 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 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 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 DiagnosticBuilder<'_>, + 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 a + // `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, + 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.normalize_to_macros_2_0()).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 { + self.crate_loader.maybe_process_path_extern(ident.name)? + }; + 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), + ) + } + }) + } + + /// This is equivalent to `get_traits_in_module_containing_item`, but without filtering by the associated item. + /// + /// This is used by rustdoc for intra-doc links. + pub fn traits_in_scope(&mut self, module_id: DefId) -> Vec<TraitCandidate> { + let module = self.get_module(module_id); + module.ensure_traits(self); + let traits = module.traits.borrow(); + let to_candidate = + |this: &mut Self, &(trait_name, binding): &(Ident, &NameBinding<'_>)| TraitCandidate { + def_id: binding.res().def_id(), + import_ids: this.find_transitive_imports(&binding.kind, trait_name), + }; + + let mut candidates: Vec<_> = + traits.as_ref().unwrap().iter().map(|x| to_candidate(self, x)).collect(); + + if let Some(prelude) = self.prelude { + if !module.no_implicit_prelude { + prelude.ensure_traits(self); + candidates.extend( + prelude.traits.borrow().as_ref().unwrap().iter().map(|x| to_candidate(self, x)), + ); + } + } + + candidates + } + + /// 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: DefId, + ) -> 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.get_module(module_id); + 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<Res, (Span, ResolutionError<'a>)> { + match self.resolve_path( + &Segment::from_path(path), + Some(ns), + parent_scope, + false, + 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<Symbol, Res> { + &self.all_macros + } + + /// Retrieves the span of the given `DefId` if `DefId` is in the local crate. + #[inline] + pub fn opt_span(&self, def_id: DefId) -> Option<Span> { + if let Some(def_id) = def_id.as_local() { Some(self.def_id_to_span[def_id]) } else { None } + } +} + +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::<Vec<_>>()) +} + +/// A somewhat inefficient routine to obtain the name of a module. +fn module_to_string(module: Module<'_>) -> Option<String> { + let mut names = Vec::new(); + + fn collect_mod(names: &mut Vec<Symbol>, 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("<opaque>")); + 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 `<T as X::Y>::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<NodeId> { + 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) { + late::lifetimes::provide(providers); +} |