use rustc_ast::{self as ast, NodeId}; use rustc_feature::is_builtin_attr_name; use rustc_hir::def::{DefKind, Namespace, NonMacroAttrKind, PartialRes, PerNS}; use rustc_hir::PrimTy; use rustc_middle::bug; use rustc_middle::ty; use rustc_session::lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK; use rustc_session::lint::BuiltinLintDiagnostics; use rustc_span::def_id::LocalDefId; use rustc_span::hygiene::{ExpnId, ExpnKind, LocalExpnId, MacroKind, SyntaxContext}; use rustc_span::symbol::{kw, Ident}; use rustc_span::{Span, DUMMY_SP}; use crate::errors::{ParamKindInEnumDiscriminant, ParamKindInNonTrivialAnonConst}; use crate::late::{ ConstantHasGenerics, HasGenericParams, NoConstantGenericsReason, PathSource, Rib, RibKind, }; use crate::macros::{sub_namespace_match, MacroRulesScope}; use crate::BindingKey; use crate::{errors, AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy, Finalize}; use crate::{ImportKind, LexicalScopeBinding, Module, ModuleKind, ModuleOrUniformRoot}; use crate::{NameBinding, NameBindingKind, ParentScope, PathResult, PrivacyError, Res}; use crate::{ResolutionError, Resolver, Scope, ScopeSet, Segment, ToNameBinding, Weak}; use Determinacy::*; use Namespace::*; type Visibility = ty::Visibility; impl<'a, 'tcx> Resolver<'a, 'tcx> { /// 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. pub(crate) fn visit_scopes( &mut self, scope_set: ScopeSet<'a>, parent_scope: &ParentScope<'a>, ctxt: SyntaxContext, mut visitor: impl FnMut( &mut Self, Scope<'a>, /*use_prelude*/ bool, SyntaxContext, ) -> Option, ) -> Option { // General principles: // 1. Not controlled (user-defined) names should have higher priority than controlled names // built into the language or standard library. This way we can add new names into the // language or standard library without breaking user code. // 2. "Closed set" below means new names cannot appear after the current resolution attempt. // Places to search (in order of decreasing priority): // (Type NS) // 1. FIXME: Ribs (type parameters), there's no necessary infrastructure yet // (open set, not controlled). // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 3. Extern prelude (open, the open part is from macro expansions, not controlled). // 4. Tool modules (closed, controlled right now, but not in the future). // 5. Standard library prelude (de-facto closed, controlled). // 6. Language prelude (closed, controlled). // (Value NS) // 1. FIXME: Ribs (local variables), there's no necessary infrastructure yet // (open set, not controlled). // 2. Names in modules (both normal `mod`ules and blocks), loop through hygienic parents // (open, not controlled). // 3. Standard library prelude (de-facto closed, controlled). // (Macro NS) // 1-3. Derive helpers (open, not controlled). All ambiguities with other names // are currently reported as errors. They should be higher in priority than preludes // and probably even names in modules according to the "general principles" above. They // also should be subject to restricted shadowing because are effectively produced by // derives (you need to resolve the derive first to add helpers into scope), but they // should be available before the derive is expanded for compatibility. // It's mess in general, so we are being conservative for now. // 1-3. `macro_rules` (open, not controlled), loop through `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 = ctxt.edition().is_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), ScopeSet::Late(ns, ..) => (ns, None, false), }; let module = match scope_set { // Start with the specified module. ScopeSet::Late(_, module, _) => module, // Jump out of trait or enum modules, they do not act as scopes. _ => parent_scope.module.nearest_item_scope(), }; let mut scope = match ns { _ if is_absolute_path => Scope::CrateRoot, TypeNS | ValueNS => Scope::Module(module, None), MacroNS => Scope::DeriveHelpers(parent_scope.expansion), }; let mut ctxt = ctxt.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(macro_rules_scope) => { // Use "path compression" on `macro_rules` scope chains. This is an optimization // used to avoid long scope chains, see the comments on `MacroRulesScopeRef`. // As another consequence of this optimization visitors never observe invocation // scopes for macros that were already expanded. while let MacroRulesScope::Invocation(invoc_id) = macro_rules_scope.get() { if let Some(next_scope) = self.output_macro_rules_scopes.get(&invoc_id) { macro_rules_scope.set(next_scope.get()); } else { break; } } true } Scope::CrateRoot => true, Scope::Module(..) => true, 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, ctxt) { return break_result; } } scope = match scope { Scope::DeriveHelpers(LocalExpnId::ROOT) => Scope::DeriveHelpersCompat, Scope::DeriveHelpers(expn_id) => { // 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.expect_local()), } } Scope::DeriveHelpersCompat => Scope::MacroRules(parent_scope.macro_rules), Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() { MacroRulesScope::Binding(binding) => { Scope::MacroRules(binding.parent_macro_rules_scope) } MacroRulesScope::Invocation(invoc_id) => { Scope::MacroRules(self.invocation_parent_scopes[&invoc_id].macro_rules) } MacroRulesScope::Empty => Scope::Module(module, None), }, Scope::CrateRoot => match ns { TypeNS => { ctxt.adjust(ExpnId::root()); Scope::ExternPrelude } ValueNS | MacroNS => break, }, Scope::Module(module, prev_lint_id) => { use_prelude = !module.no_implicit_prelude; let derive_fallback_lint_id = match scope_set { ScopeSet::Late(.., lint_id) => lint_id, _ => None, }; match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) { Some((parent_module, lint_id)) => { Scope::Module(parent_module, lint_id.or(prev_lint_id)) } None => { ctxt.adjust(ExpnId::root()); match ns { TypeNS => Scope::ExternPrelude, ValueNS => Scope::StdLibPrelude, MacroNS => 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 } fn hygienic_lexical_parent( &mut self, module: Module<'a>, ctxt: &mut SyntaxContext, derive_fallback_lint_id: Option, ) -> Option<(Module<'a>, Option)> { if !module.expansion.outer_expn_is_descendant_of(*ctxt) { return Some((self.expn_def_scope(ctxt.remove_mark()), None)); } if let ModuleKind::Block = module.kind { return Some((module.parent.unwrap().nearest_item_scope(), None)); } // 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 derive_fallback_lint_id.is_some() { 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 { let ext = self.get_macro_by_def_id(def_id).ext; if ext.builtin_name.is_none() && ext.macro_kind() == MacroKind::Derive && parent.expansion.outer_expn_is_descendant_of(*ctxt) { return Some((parent, derive_fallback_lint_id)); } } } } } 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. #[instrument(level = "debug", skip(self, ribs))] pub(crate) fn resolve_ident_in_lexical_scope( &mut self, mut ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, finalize: Option, ribs: &[Rib<'a>], ignore_binding: Option>, ) -> Option> { assert!(ns == TypeNS || ns == ValueNS); let orig_ident = ident; if ident.name == kw::Empty { 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 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((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident) { // The ident resolves to a type parameter or local variable. return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs( i, rib_ident, *res, finalize.map(|finalize| finalize.path_span), *original_rib_ident_def, ribs, ))); } module = match ribs[i].kind { RibKind::Module(module) => module, RibKind::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, }; match module.kind { ModuleKind::Block => {} // We can see through blocks _ => break, } let item = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(module), ident, ns, parent_scope, finalize, ignore_binding, ); if let Ok(binding) = item { // The ident resolves to an item. return Some(LexicalScopeBinding::Item(binding)); } } self.early_resolve_ident_in_lexical_scope( orig_ident, ScopeSet::Late(ns, module, finalize.map(|finalize| finalize.node_id)), parent_scope, finalize, finalize.is_some(), ignore_binding, ) .ok() .map(LexicalScopeBinding::Item) } /// Resolve an identifier in lexical scope. /// This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during /// expansion and import resolution (perhaps they can be merged in the future). /// The function is used for resolving initial segments of macro paths (e.g., `foo` in /// `foo::bar!();` or `foo!();`) and also for import paths on 2018 edition. #[instrument(level = "debug", skip(self))] pub(crate) fn early_resolve_ident_in_lexical_scope( &mut self, orig_ident: Ident, scope_set: ScopeSet<'a>, parent_scope: &ParentScope<'a>, finalize: Option, force: bool, ignore_binding: Option>, ) -> Result, Determinacy> { bitflags::bitflags! { struct Flags: u8 { const MACRO_RULES = 1 << 0; const MODULE = 1 << 1; const MISC_SUGGEST_CRATE = 1 << 2; const MISC_SUGGEST_SELF = 1 << 3; const MISC_FROM_PRELUDE = 1 << 4; } } assert!(force || finalize.is_none()); // `finalize` implies `force` // Make sure `self`, `super` etc produce an error when passed to here. if orig_ident.is_path_segment_keyword() { return Err(Determinacy::Determined); } let (ns, macro_kind) = match scope_set { ScopeSet::All(ns) => (ns, None), ScopeSet::AbsolutePath(ns) => (ns, None), ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind)), ScopeSet::Late(ns, ..) => (ns, None), }; // This is *the* result, resolution from the scope closest to the resolved identifier. // However, sometimes this result is "weak" because it comes from a glob import or // a macro expansion, and in this case it cannot shadow names from outer scopes, e.g. // mod m { ... } // solution in outer scope // { // use prefix::*; // imports another `m` - innermost solution // // weak, cannot shadow the outer `m`, need to report ambiguity error // m::mac!(); // } // So we have to save the innermost solution and continue searching in outer scopes // to detect potential ambiguities. let mut innermost_result: Option<(NameBinding<'_>, Flags)> = None; let mut determinacy = Determinacy::Determined; // Go through all the scopes and try to resolve the name. let break_result = self.visit_scopes( scope_set, parent_scope, orig_ident.span.ctxt(), |this, scope, use_prelude, ctxt| { let ident = Ident::new(orig_ident.name, orig_ident.span.with_ctxt(ctxt)); let ok = |res, span, arenas| { Ok(( (res, Visibility::Public, span, LocalExpnId::ROOT).to_name_binding(arenas), Flags::empty(), )) }; let result = match scope { Scope::DeriveHelpers(expn_id) => { if let Some(attr) = this .helper_attrs .get(&expn_id) .and_then(|attrs| attrs.iter().rfind(|i| ident == **i)) { let binding = ( Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper), Visibility::Public, attr.span, expn_id, ) .to_name_binding(this.arenas); Ok((binding, Flags::empty())) } else { Err(Determinacy::Determined) } } Scope::DeriveHelpersCompat => { let mut result = Err(Determinacy::Determined); for derive in parent_scope.derives { let parent_scope = &ParentScope { derives: &[], ..*parent_scope }; match this.resolve_macro_path( derive, Some(MacroKind::Derive), parent_scope, true, force, ) { Ok((Some(ext), _)) => { if ext.helper_attrs.contains(&ident.name) { result = ok( Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat), derive.span, this.arenas, ); break; } } Ok(_) | Err(Determinacy::Determined) => {} Err(Determinacy::Undetermined) => { result = Err(Determinacy::Undetermined) } } } result } Scope::MacroRules(macro_rules_scope) => match macro_rules_scope.get() { MacroRulesScope::Binding(macro_rules_binding) if ident == macro_rules_binding.ident => { Ok((macro_rules_binding.binding, Flags::MACRO_RULES)) } MacroRulesScope::Invocation(_) => Err(Determinacy::Undetermined), _ => Err(Determinacy::Determined), }, Scope::CrateRoot => { let root_ident = Ident::new(kw::PathRoot, ident.span); let root_module = this.resolve_crate_root(root_ident); let binding = this.resolve_ident_in_module_ext( ModuleOrUniformRoot::Module(root_module), ident, ns, parent_scope, finalize, ignore_binding, ); match binding { Ok(binding) => Ok((binding, Flags::MODULE | Flags::MISC_SUGGEST_CRATE)), Err((Determinacy::Undetermined, Weak::No)) => { return Some(Err(Determinacy::determined(force))); } Err((Determinacy::Undetermined, Weak::Yes)) => { Err(Determinacy::Undetermined) } Err((Determinacy::Determined, _)) => Err(Determinacy::Determined), } } Scope::Module(module, derive_fallback_lint_id) => { let adjusted_parent_scope = &ParentScope { module, ..*parent_scope }; let binding = this.resolve_ident_in_module_unadjusted_ext( ModuleOrUniformRoot::Module(module), ident, ns, adjusted_parent_scope, !matches!(scope_set, ScopeSet::Late(..)), finalize, ignore_binding, ); match binding { Ok(binding) => { if let Some(lint_id) = derive_fallback_lint_id { this.lint_buffer.buffer_lint_with_diagnostic( PROC_MACRO_DERIVE_RESOLUTION_FALLBACK, lint_id, orig_ident.span, format!( "cannot find {} `{}` in this scope", ns.descr(), ident ), BuiltinLintDiagnostics::ProcMacroDeriveResolutionFallback( orig_ident.span, ), ); } let misc_flags = if module == this.graph_root { Flags::MISC_SUGGEST_CRATE } else if module.is_normal() { Flags::MISC_SUGGEST_SELF } else { Flags::empty() }; Ok((binding, Flags::MODULE | misc_flags)) } Err((Determinacy::Undetermined, Weak::No)) => { return Some(Err(Determinacy::determined(force))); } Err((Determinacy::Undetermined, Weak::Yes)) => { Err(Determinacy::Undetermined) } Err((Determinacy::Determined, _)) => Err(Determinacy::Determined), } } Scope::MacroUsePrelude => { match this.macro_use_prelude.get(&ident.name).cloned() { Some(binding) => Ok((binding, Flags::MISC_FROM_PRELUDE)), None => Err(Determinacy::determined( this.graph_root.unexpanded_invocations.borrow().is_empty(), )), } } Scope::BuiltinAttrs => { if is_builtin_attr_name(ident.name) { ok( Res::NonMacroAttr(NonMacroAttrKind::Builtin(ident.name)), DUMMY_SP, this.arenas, ) } else { Err(Determinacy::Determined) } } Scope::ExternPrelude => { match this.extern_prelude_get(ident, finalize.is_some()) { Some(binding) => Ok((binding, Flags::empty())), None => Err(Determinacy::determined( this.graph_root.unexpanded_invocations.borrow().is_empty(), )), } } Scope::ToolPrelude => match this.registered_tools.get(&ident).cloned() { Some(ident) => ok(Res::ToolMod, ident.span, this.arenas), None => Err(Determinacy::Determined), }, Scope::StdLibPrelude => { let mut result = Err(Determinacy::Determined); if let Some(prelude) = this.prelude { if let Ok(binding) = this.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(prelude), ident, ns, parent_scope, None, ignore_binding, ) { if use_prelude || this.is_builtin_macro(binding.res()) { result = Ok((binding, Flags::MISC_FROM_PRELUDE)); } } } result } Scope::BuiltinTypes => match PrimTy::from_name(ident.name) { Some(prim_ty) => ok(Res::PrimTy(prim_ty), DUMMY_SP, this.arenas), None => Err(Determinacy::Determined), }, }; match result { Ok((binding, flags)) if sub_namespace_match(binding.macro_kind(), macro_kind) => { if finalize.is_none() || matches!(scope_set, ScopeSet::Late(..)) { return Some(Ok(binding)); } if let Some((innermost_binding, innermost_flags)) = innermost_result { // Found another solution, if the first one was "weak", report an error. let (res, innermost_res) = (binding.res(), innermost_binding.res()); if res != innermost_res { let is_builtin = |res| { matches!(res, Res::NonMacroAttr(NonMacroAttrKind::Builtin(..))) }; let derive_helper = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper); let derive_helper_compat = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat); let ambiguity_error_kind = if is_builtin(innermost_res) || is_builtin(res) { Some(AmbiguityKind::BuiltinAttr) } else if innermost_res == derive_helper_compat || res == derive_helper_compat && innermost_res != derive_helper { Some(AmbiguityKind::DeriveHelper) } else if innermost_flags.contains(Flags::MACRO_RULES) && flags.contains(Flags::MODULE) && !this.disambiguate_macro_rules_vs_modularized( innermost_binding, binding, ) || flags.contains(Flags::MACRO_RULES) && innermost_flags.contains(Flags::MODULE) && !this.disambiguate_macro_rules_vs_modularized( binding, innermost_binding, ) { Some(AmbiguityKind::MacroRulesVsModularized) } else if innermost_binding.is_glob_import() { Some(AmbiguityKind::GlobVsOuter) } else if innermost_binding .may_appear_after(parent_scope.expansion, binding) { Some(AmbiguityKind::MoreExpandedVsOuter) } else { None }; if let Some(kind) = ambiguity_error_kind { let misc = |f: Flags| { if f.contains(Flags::MISC_SUGGEST_CRATE) { AmbiguityErrorMisc::SuggestCrate } else if f.contains(Flags::MISC_SUGGEST_SELF) { AmbiguityErrorMisc::SuggestSelf } else if f.contains(Flags::MISC_FROM_PRELUDE) { AmbiguityErrorMisc::FromPrelude } else { AmbiguityErrorMisc::None } }; this.ambiguity_errors.push(AmbiguityError { kind, ident: orig_ident, b1: innermost_binding, b2: binding, misc1: misc(innermost_flags), misc2: misc(flags), }); return Some(Ok(innermost_binding)); } } } else { // Found the first solution. innermost_result = Some((binding, flags)); } } Ok(..) | Err(Determinacy::Determined) => {} Err(Determinacy::Undetermined) => determinacy = Determinacy::Undetermined, } None }, ); if let Some(break_result) = break_result { return break_result; } // The first found solution was the only one, return it. if let Some((binding, _)) = innermost_result { return Ok(binding); } Err(Determinacy::determined(determinacy == Determinacy::Determined || force)) } #[instrument(level = "debug", skip(self))] pub(crate) fn maybe_resolve_ident_in_module( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, ) -> Result, Determinacy> { self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, None, None) .map_err(|(determinacy, _)| determinacy) } #[instrument(level = "debug", skip(self))] pub(crate) fn resolve_ident_in_module( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, finalize: Option, ignore_binding: Option>, ) -> Result, Determinacy> { self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, finalize, ignore_binding) .map_err(|(determinacy, _)| determinacy) } #[instrument(level = "debug", skip(self))] fn resolve_ident_in_module_ext( &mut self, module: ModuleOrUniformRoot<'a>, mut ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, finalize: Option, ignore_binding: Option>, ) -> Result, (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.expn_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, finalize, ignore_binding, ) } #[instrument(level = "debug", skip(self))] fn resolve_ident_in_module_unadjusted( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, finalize: Option, ignore_binding: Option>, ) -> Result, Determinacy> { self.resolve_ident_in_module_unadjusted_ext( module, ident, ns, parent_scope, false, finalize, ignore_binding, ) .map_err(|(determinacy, _)| determinacy) } /// Attempts to resolve `ident` in namespaces `ns` of `module`. /// Invariant: if `finalize` is `Some`, expansion and import resolution must be complete. #[instrument(level = "debug", skip(self))] fn resolve_ident_in_module_unadjusted_ext( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, restricted_shadowing: bool, finalize: Option, // This binding should be ignored during in-module resolution, so that we don't get // "self-confirming" import resolutions during import validation and checking. ignore_binding: Option>, ) -> Result, (Determinacy, Weak)> { let module = match module { ModuleOrUniformRoot::Module(module) => module, ModuleOrUniformRoot::CrateRootAndExternPrelude => { assert!(!restricted_shadowing); let binding = self.early_resolve_ident_in_lexical_scope( ident, ScopeSet::AbsolutePath(ns), parent_scope, finalize, finalize.is_some(), ignore_binding, ); return binding.map_err(|determinacy| (determinacy, Weak::No)); } ModuleOrUniformRoot::ExternPrelude => { assert!(!restricted_shadowing); return if ns != TypeNS { Err((Determined, Weak::No)) } else if let Some(binding) = self.extern_prelude_get(ident, finalize.is_some()) { Ok(binding) } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() { // Macro-expanded `extern crate` items can add names to extern prelude. Err((Undetermined, Weak::No)) } else { Err((Determined, Weak::No)) }; } ModuleOrUniformRoot::CurrentScope => { assert!(!restricted_shadowing); if ns == TypeNS { if ident.name == kw::Crate || ident.name == kw::DollarCrate { let module = self.resolve_crate_root(ident); let binding = (module, Visibility::Public, module.span, LocalExpnId::ROOT) .to_name_binding(self.arenas); return Ok(binding); } else if ident.name == kw::Super || ident.name == kw::SelfLower { // FIXME: Implement these with renaming requirements so that e.g. // `use super;` doesn't work, but `use super as name;` does. // Fall through here to get an error from `early_resolve_...`. } } let binding = self.early_resolve_ident_in_lexical_scope( ident, ScopeSet::All(ns), parent_scope, finalize, finalize.is_some(), ignore_binding, ); return binding.map_err(|determinacy| (determinacy, Weak::No)); } }; let key = BindingKey::new(ident, ns); let resolution = self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports. // If the primary binding is unusable, search further and return the shadowed glob // binding if it exists. What we really want here is having two separate scopes in // a module - one for non-globs and one for globs, but until that's done use this // hack to avoid inconsistent resolution ICEs during import validation. let binding = [resolution.binding, resolution.shadowed_glob] .into_iter() .find_map(|binding| if binding == ignore_binding { None } else { binding }); if let Some(Finalize { path_span, report_private, .. }) = finalize { let Some(binding) = binding else { return Err((Determined, Weak::No)); }; if !self.is_accessible_from(binding.vis, parent_scope.module) { if report_private { self.privacy_errors.push(PrivacyError { ident, binding, dedup_span: path_span, outermost_res: None, parent_scope: *parent_scope, }); } else { return Err((Determined, Weak::No)); } } // Forbid expanded shadowing to avoid time travel. if let Some(shadowed_glob) = resolution.shadowed_glob && restricted_shadowing && binding.expansion != LocalExpnId::ROOT && binding.res() != shadowed_glob.res() { self.ambiguity_errors.push(AmbiguityError { kind: AmbiguityKind::GlobVsExpanded, ident, b1: binding, b2: shadowed_glob, misc1: AmbiguityErrorMisc::None, misc2: AmbiguityErrorMisc::None, }); } if !restricted_shadowing && binding.expansion != LocalExpnId::ROOT { if let NameBindingKind::Import { import, .. } = binding.kind && matches!(import.kind, ImportKind::MacroExport) { self.macro_expanded_macro_export_errors.insert((path_span, binding.span)); } } self.record_use(ident, binding, restricted_shadowing); return Ok(binding); } let check_usable = |this: &mut Self, binding: NameBinding<'a>| { let usable = this.is_accessible_from(binding.vis, parent_scope.module); if usable { Ok(binding) } else { Err((Determined, Weak::No)) } }; // Items and single imports are not shadowable, if we have one, then it's determined. if let Some(binding) = binding { if !binding.is_glob_import() { return check_usable(self, binding); } } // --- From now on we either have a glob resolution or no resolution. --- // Check if one of single imports can still define the name, // if it can then our result is not determined and can be invalidated. for single_import in &resolution.single_imports { let Some(import_vis) = single_import.vis.get() else { continue; }; if !self.is_accessible_from(import_vis, parent_scope.module) { continue; } if let Some(ignored) = ignore_binding && let NameBindingKind::Import { import, .. } = ignored.kind && import == *single_import { // Ignore not just the binding itself, but if it has a shadowed_glob, // ignore that, too, because this loop is supposed to only process // named imports. continue; } let Some(module) = single_import.imported_module.get() else { return Err((Undetermined, Weak::No)); }; let ImportKind::Single { source: ident, .. } = single_import.kind else { unreachable!(); }; match self.resolve_ident_in_module( module, ident, ns, &single_import.parent_scope, None, ignore_binding, ) { Err(Determined) => continue, Ok(binding) if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) => { continue; } Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)), } } // So we have a resolution that's from a glob import. This resolution is determined // if it cannot be shadowed by some new item/import expanded from a macro. // This happens either if there are no unexpanded macros, or expanded names cannot // shadow globs (that happens in macro namespace or with restricted shadowing). // // Additionally, any macro in any module can plant names in the root module if it creates // `macro_export` macros, so the root module effectively has unresolved invocations if any // module has unresolved invocations. // However, it causes resolution/expansion to stuck too often (#53144), so, to make // progress, we have to ignore those potential unresolved invocations from other modules // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted // shadowing is enabled, see `macro_expanded_macro_export_errors`). let unexpanded_macros = !module.unexpanded_invocations.borrow().is_empty(); if let Some(binding) = binding { if !unexpanded_macros || ns == MacroNS || restricted_shadowing { return check_usable(self, binding); } else { return Err((Undetermined, Weak::No)); } } // --- From now on we have no resolution. --- // Now we are in situation when new item/import can appear only from a glob or a macro // expansion. With restricted shadowing names from globs and macro expansions cannot // shadow names from outer scopes, so we can freely fallback from module search to search // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer // scopes we return `Undetermined` with `Weak::Yes`. // Check if one of unexpanded macros can still define the name, // if it can then our "no resolution" result is not determined and can be invalidated. if unexpanded_macros { return Err((Undetermined, Weak::Yes)); } // Check if one of glob imports can still define the name, // if it can then our "no resolution" result is not determined and can be invalidated. for glob_import in module.globs.borrow().iter() { let Some(import_vis) = glob_import.vis.get() else { continue; }; if !self.is_accessible_from(import_vis, parent_scope.module) { continue; } let module = match glob_import.imported_module.get() { Some(ModuleOrUniformRoot::Module(module)) => module, Some(_) => continue, None => return Err((Undetermined, Weak::Yes)), }; let tmp_parent_scope; let (mut adjusted_parent_scope, mut ident) = (parent_scope, ident.normalize_to_macros_2_0()); match ident.span.glob_adjust(module.expansion, glob_import.span) { Some(Some(def)) => { tmp_parent_scope = ParentScope { module: self.expn_def_scope(def), ..*parent_scope }; adjusted_parent_scope = &tmp_parent_scope; } Some(None) => {} None => continue, }; let result = self.resolve_ident_in_module_unadjusted( ModuleOrUniformRoot::Module(module), ident, ns, adjusted_parent_scope, None, ignore_binding, ); match result { Err(Determined) => continue, Ok(binding) if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) => { continue; } Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)), } } // No resolution and no one else can define the name - determinate error. Err((Determined, Weak::No)) } /// Validate a local resolution (from ribs). #[instrument(level = "debug", skip(self, all_ribs))] fn validate_res_from_ribs( &mut self, rib_index: usize, rib_ident: Ident, mut res: Res, finalize: Option, original_rib_ident_def: Ident, all_ribs: &[Rib<'a>], ) -> Res { const CG_BUG_STR: &str = "min_const_generics resolve check didn't stop compilation"; debug!("validate_res_from_ribs({:?})", res); let ribs = &all_ribs[rib_index + 1..]; // An invalid forward use of a generic parameter from a previous default. if let RibKind::ForwardGenericParamBan = all_ribs[rib_index].kind { if let Some(span) = finalize { let res_error = if rib_ident.name == kw::SelfUpper { ResolutionError::SelfInGenericParamDefault } else { ResolutionError::ForwardDeclaredGenericParam }; 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 { RibKind::Normal | RibKind::ClosureOrAsync | RibKind::Module(..) | RibKind::MacroDefinition(..) | RibKind::ForwardGenericParamBan => { // Nothing to do. Continue. } RibKind::Item(_) | RibKind::AssocItem => { // This was an attempt to access an upvar inside a // named function item. This is not allowed, so we // report an error. if let Some(span) = finalize { // 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((span, CannotCaptureDynamicEnvironmentInFnItem)); } } RibKind::ConstantItem(_, item) => { // Still doesn't deal with upvars if let Some(span) = finalize { let (span, resolution_error) = match item { None if rib_ident.as_str() == "self" => (span, LowercaseSelf), None => ( rib_ident.span, AttemptToUseNonConstantValueInConstant( original_rib_ident_def, "const", "let", ), ), Some((ident, kind)) => ( span, AttemptToUseNonConstantValueInConstant( ident, "let", kind.as_str(), ), ), }; self.report_error(span, resolution_error); } return Res::Err; } RibKind::ConstParamTy => { if let Some(span) = finalize { self.report_error( span, ParamInTyOfConstParam { name: rib_ident.name, param_kind: None, }, ); } return Res::Err; } RibKind::InlineAsmSym => { if let Some(span) = finalize { self.report_error(span, InvalidAsmSym); } return Res::Err; } } } if let Some((span, res_err)) = res_err { self.report_error(span, res_err); return Res::Err; } } Res::Def(DefKind::TyParam, _) | Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } => { for rib in ribs { let has_generic_params: HasGenericParams = match rib.kind { RibKind::Normal | RibKind::ClosureOrAsync | RibKind::Module(..) | RibKind::MacroDefinition(..) | RibKind::InlineAsmSym | RibKind::AssocItem | RibKind::ForwardGenericParamBan => { // Nothing to do. Continue. continue; } RibKind::ConstantItem(trivial, _) => { if let ConstantHasGenerics::No(cause) = trivial { // HACK(min_const_generics): If we encounter `Self` in an anonymous // constant we can't easily tell if it's generic at this stage, so // we instead remember this and then enforce the self type to be // concrete later on. if let Res::SelfTyAlias { alias_to: def, forbid_generic: _, is_trait_impl, } = res { res = Res::SelfTyAlias { alias_to: def, forbid_generic: true, is_trait_impl, } } else { if let Some(span) = finalize { let error = match cause { NoConstantGenericsReason::IsEnumDiscriminant => { ResolutionError::ParamInEnumDiscriminant { name: rib_ident.name, param_kind: ParamKindInEnumDiscriminant::Type, } } NoConstantGenericsReason::NonTrivialConstArg => { ResolutionError::ParamInNonTrivialAnonConst { name: rib_ident.name, param_kind: ParamKindInNonTrivialAnonConst::Type, } } }; self.report_error(span, error); self.tcx.sess.delay_span_bug(span, CG_BUG_STR); } return Res::Err; } } continue; } // This was an attempt to use a type parameter outside its scope. RibKind::Item(has_generic_params) => has_generic_params, RibKind::ConstParamTy => { if let Some(span) = finalize { self.report_error( span, ResolutionError::ParamInTyOfConstParam { name: rib_ident.name, param_kind: Some(errors::ParamKindInTyOfConstParam::Type), }, ); } return Res::Err; } }; if let Some(span) = finalize { self.report_error( span, ResolutionError::GenericParamsFromOuterFunction( res, has_generic_params, ), ); } return Res::Err; } } Res::Def(DefKind::ConstParam, _) => { for rib in ribs { let has_generic_params = match rib.kind { RibKind::Normal | RibKind::ClosureOrAsync | RibKind::Module(..) | RibKind::MacroDefinition(..) | RibKind::InlineAsmSym | RibKind::AssocItem | RibKind::ForwardGenericParamBan => continue, RibKind::ConstantItem(trivial, _) => { if let ConstantHasGenerics::No(cause) = trivial { if let Some(span) = finalize { let error = match cause { NoConstantGenericsReason::IsEnumDiscriminant => { ResolutionError::ParamInEnumDiscriminant { name: rib_ident.name, param_kind: ParamKindInEnumDiscriminant::Const, } } NoConstantGenericsReason::NonTrivialConstArg => { ResolutionError::ParamInNonTrivialAnonConst { name: rib_ident.name, param_kind: ParamKindInNonTrivialAnonConst::Const { name: rib_ident.name, }, } } }; self.report_error(span, error); } return Res::Err; } continue; } RibKind::Item(has_generic_params) => has_generic_params, RibKind::ConstParamTy => { if let Some(span) = finalize { self.report_error( span, ResolutionError::ParamInTyOfConstParam { name: rib_ident.name, param_kind: Some(errors::ParamKindInTyOfConstParam::Const), }, ); } return Res::Err; } }; // This was an attempt to use a const parameter outside its scope. if let Some(span) = finalize { self.report_error( span, ResolutionError::GenericParamsFromOuterFunction( res, has_generic_params, ), ); } return Res::Err; } } _ => {} } res } #[instrument(level = "debug", skip(self))] pub(crate) fn maybe_resolve_path( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, ) -> PathResult<'a> { self.resolve_path_with_ribs(path, opt_ns, parent_scope, None, None, None) } #[instrument(level = "debug", skip(self))] pub(crate) fn resolve_path( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, finalize: Option, ignore_binding: Option>, ) -> PathResult<'a> { self.resolve_path_with_ribs(path, opt_ns, parent_scope, finalize, None, ignore_binding) } pub(crate) fn resolve_path_with_ribs( &mut self, path: &[Segment], opt_ns: Option, // `None` indicates a module path in import parent_scope: &ParentScope<'a>, finalize: Option, ribs: Option<&PerNS>>>, ignore_binding: Option>, ) -> PathResult<'a> { let mut module = None; let mut allow_super = true; let mut second_binding = None; // We'll provide more context to the privacy errors later, up to `len`. let privacy_errors_len = self.privacy_errors.len(); for (segment_idx, &Segment { ident, id, .. }) in path.iter().enumerate() { debug!("resolve_path ident {} {:?} {:?}", segment_idx, ident, id); let record_segment_res = |this: &mut Self, res| { if finalize.is_some() { 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 = segment_idx + 1 == path.len(); 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 segment_idx { 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; } } return PathResult::failed( ident.span, false, finalize.is_some(), module, || ("there are too many leading `super` keywords".to_string(), None), ); } if segment_idx == 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.is_rust_2015() && self.tcx.sess.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() && segment_idx != 0 { return PathResult::failed(ident.span, false, finalize.is_some(), module, || { let name_str = if name == kw::PathRoot { "crate root".to_string() } else { format!("`{}`", name) }; let label = if segment_idx == 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) }; (label, None) }); } let binding = if let Some(module) = module { self.resolve_ident_in_module( module, ident, ns, parent_scope, finalize, ignore_binding, ) } else if let Some(ribs) = ribs && let Some(TypeNS | ValueNS) = opt_ns { match self.resolve_ident_in_lexical_scope( ident, ns, parent_scope, finalize, &ribs[ns], ignore_binding, ) { // 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)) => { record_segment_res(self, res); return PathResult::NonModule(PartialRes::with_unresolved_segments( res, path.len() - 1, )); } _ => Err(Determinacy::determined(finalize.is_some())), } } else { self.early_resolve_ident_in_lexical_scope( ident, ScopeSet::All(ns), parent_scope, finalize, finalize.is_some(), ignore_binding, ) }; match binding { Ok(binding) => { if segment_idx == 1 { second_binding = Some(binding); } let res = binding.res(); // Mark every privacy error in this path with the res to the last element. This allows us // to detect the item the user cares about and either find an alternative import, or tell // the user it is not accessible. for error in &mut self.privacy_errors[privacy_errors_len..] { error.outermost_res = Some((res, ident)); } 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 && !is_last && opt_ns.is_some() { if binding.is_import() { self.tcx.sess.emit_err(errors::ToolModuleImported { span: ident.span, import: binding.span, }); } 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(finalize, path, second_binding); record_segment_res(self, res); return PathResult::NonModule(PartialRes::with_unresolved_segments( res, path.len() - segment_idx - 1, )); } else { return PathResult::failed( ident.span, is_last, finalize.is_some(), module, || { let label = format!( "`{ident}` is {} {}, not a module", res.article(), res.descr() ); (label, None) }, ); } } 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() - segment_idx, )); } } return PathResult::failed( ident.span, is_last, finalize.is_some(), module, || { self.report_path_resolution_error( path, opt_ns, parent_scope, ribs, ignore_binding, module, segment_idx, ident, ) }, ); } } } self.lint_if_path_starts_with_module(finalize, path, second_binding); PathResult::Module(match module { Some(module) => module, None if path.is_empty() => ModuleOrUniformRoot::CurrentScope, _ => bug!("resolve_path: non-empty path `{:?}` has no module", path), }) } }