// Copyright 2015 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use self::ImportDirectiveSubclass::*; use {AmbiguityError, Module, PerNS}; use Namespace::{self, TypeNS, MacroNS}; use {NameBinding, NameBindingKind, ToNameBinding, PathResult, PrivacyError}; use Resolver; use {names_to_string, module_to_string}; use {resolve_error, ResolutionError}; use rustc::ty; use rustc::lint::builtin::PUB_USE_OF_PRIVATE_EXTERN_CRATE; use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId}; use rustc::hir::def::*; use rustc::session::DiagnosticMessageId; use rustc::util::nodemap::{FxHashMap, FxHashSet}; use syntax::ast::{Ident, Name, SpannedIdent, NodeId}; use syntax::ext::base::Determinacy::{self, Determined, Undetermined}; use syntax::ext::hygiene::Mark; use syntax::parse::token; use syntax::symbol::keywords; use syntax::util::lev_distance::find_best_match_for_name; use syntax_pos::Span; use std::cell::{Cell, RefCell}; use std::mem; /// Contains data for specific types of import directives. #[derive(Clone, Debug)] pub enum ImportDirectiveSubclass<'a> { SingleImport { target: Ident, source: Ident, result: PerNS, Determinacy>>>, type_ns_only: bool, }, GlobImport { is_prelude: bool, max_vis: Cell, // The visibility of the greatest re-export. // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors. }, ExternCrate(Option), MacroUse, } /// One import directive. #[derive(Debug,Clone)] pub struct ImportDirective<'a> { pub id: NodeId, pub parent: Module<'a>, pub module_path: Vec, pub imported_module: Cell>>, // the resolution of `module_path` pub subclass: ImportDirectiveSubclass<'a>, pub span: Span, pub vis: Cell, pub expansion: Mark, pub used: Cell, } impl<'a> ImportDirective<'a> { pub fn is_glob(&self) -> bool { match self.subclass { ImportDirectiveSubclass::GlobImport { .. } => true, _ => false } } } #[derive(Clone, Default, Debug)] /// Records information about the resolution of a name in a namespace of a module. pub struct NameResolution<'a> { /// The single imports that define the name in the namespace. single_imports: SingleImports<'a>, /// The least shadowable known binding for this name, or None if there are no known bindings. pub binding: Option<&'a NameBinding<'a>>, shadows_glob: Option<&'a NameBinding<'a>>, } #[derive(Clone, Debug)] enum SingleImports<'a> { /// No single imports can define the name in the namespace. None, /// Only the given single import can define the name in the namespace. MaybeOne(&'a ImportDirective<'a>), /// At least one single import will define the name in the namespace. AtLeastOne, } impl<'a> Default for SingleImports<'a> { /// Creates a `SingleImports<'a>` of None type. fn default() -> Self { SingleImports::None } } impl<'a> SingleImports<'a> { fn add_directive(&mut self, directive: &'a ImportDirective<'a>) { match *self { SingleImports::None => *self = SingleImports::MaybeOne(directive), // If two single imports can define the name in the namespace, we can assume that at // least one of them will define it since otherwise both would have to define only one // namespace, leading to a duplicate error. SingleImports::MaybeOne(_) => *self = SingleImports::AtLeastOne, SingleImports::AtLeastOne => {} }; } fn directive_failed(&mut self) { match *self { SingleImports::None => unreachable!(), SingleImports::MaybeOne(_) => *self = SingleImports::None, SingleImports::AtLeastOne => {} } } } impl<'a> NameResolution<'a> { // Returns the binding for the name if it is known or None if it not known. fn binding(&self) -> Option<&'a NameBinding<'a>> { self.binding.and_then(|binding| match self.single_imports { SingleImports::None => Some(binding), _ if !binding.is_glob_import() => Some(binding), _ => None, // The binding could be shadowed by a single import, so it is not known. }) } } impl<'a> Resolver<'a> { fn resolution(&self, module: Module<'a>, ident: Ident, ns: Namespace) -> &'a RefCell> { *module.resolutions.borrow_mut().entry((ident.modern(), ns)) .or_insert_with(|| self.arenas.alloc_name_resolution()) } /// Attempts to resolve `ident` in namespaces `ns` of `module`. /// Invariant: if `record_used` is `Some`, import resolution must be complete. pub fn resolve_ident_in_module_unadjusted(&mut self, module: Module<'a>, ident: Ident, ns: Namespace, restricted_shadowing: bool, record_used: bool, path_span: Span) -> Result<&'a NameBinding<'a>, Determinacy> { self.populate_module_if_necessary(module); let resolution = self.resolution(module, ident, ns) .try_borrow_mut() .map_err(|_| Determined)?; // This happens when there is a cycle of imports if record_used { if let Some(binding) = resolution.binding { if let Some(shadowed_glob) = resolution.shadows_glob { let name = ident.name; // Forbid expanded shadowing to avoid time travel. if restricted_shadowing && binding.expansion != Mark::root() && ns != MacroNS && // In MacroNS, `try_define` always forbids this shadowing binding.def() != shadowed_glob.def() { self.ambiguity_errors.push(AmbiguityError { span: path_span, name, lexical: false, b1: binding, b2: shadowed_glob, legacy: false, }); } } if self.record_use(ident, ns, binding, path_span) { return Ok(self.dummy_binding); } if !self.is_accessible(binding.vis) { self.privacy_errors.push(PrivacyError(path_span, ident.name, binding)); } } return resolution.binding.ok_or(Determined); } let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| { // `extern crate` are always usable for backwards compatibility, see issue #37020. let usable = this.is_accessible(binding.vis) || binding.is_extern_crate(); if usable { Ok(binding) } else { Err(Determined) } }; // Items and single imports are not shadowable. if let Some(binding) = resolution.binding { if !binding.is_glob_import() { return check_usable(self, binding); } } // Check if a single import can still define the name. match resolution.single_imports { SingleImports::AtLeastOne => return Err(Undetermined), SingleImports::MaybeOne(directive) if self.is_accessible(directive.vis.get()) => { let module = match directive.imported_module.get() { Some(module) => module, None => return Err(Undetermined), }; let ident = match directive.subclass { SingleImport { source, .. } => source, _ => unreachable!(), }; match self.resolve_ident_in_module(module, ident, ns, false, false, path_span) { Err(Determined) => {} _ => return Err(Undetermined), } } SingleImports::MaybeOne(_) | SingleImports::None => {}, } let no_unresolved_invocations = restricted_shadowing || module.unresolved_invocations.borrow().is_empty(); match resolution.binding { // In `MacroNS`, expanded bindings do not shadow (enforced in `try_define`). Some(binding) if no_unresolved_invocations || ns == MacroNS => return check_usable(self, binding), None if no_unresolved_invocations => {} _ => return Err(Undetermined), } // Check if the globs are determined if restricted_shadowing && module.def().is_some() { return Err(Determined); } for directive in module.globs.borrow().iter() { if !self.is_accessible(directive.vis.get()) { continue } let module = unwrap_or!(directive.imported_module.get(), return Err(Undetermined)); let (orig_current_module, mut ident) = (self.current_module, ident.modern()); match ident.ctxt.glob_adjust(module.expansion, directive.span.ctxt().modern()) { Some(Some(def)) => self.current_module = self.macro_def_scope(def), Some(None) => {} None => continue, }; let result = self.resolve_ident_in_module_unadjusted( module, ident, ns, false, false, path_span, ); self.current_module = orig_current_module; if let Err(Undetermined) = result { return Err(Undetermined); } } Err(Determined) } // Add an import directive to the current module. pub fn add_import_directive(&mut self, module_path: Vec, subclass: ImportDirectiveSubclass<'a>, span: Span, id: NodeId, vis: ty::Visibility, expansion: Mark) { let current_module = self.current_module; let directive = self.arenas.alloc_import_directive(ImportDirective { parent: current_module, module_path, imported_module: Cell::new(None), subclass, span, id, vis: Cell::new(vis), expansion, used: Cell::new(false), }); self.indeterminate_imports.push(directive); match directive.subclass { SingleImport { target, .. } => { self.per_ns(|this, ns| { let mut resolution = this.resolution(current_module, target, ns).borrow_mut(); resolution.single_imports.add_directive(directive); }); } // We don't add prelude imports to the globs since they only affect lexical scopes, // which are not relevant to import resolution. GlobImport { is_prelude: true, .. } => {} GlobImport { .. } => self.current_module.globs.borrow_mut().push(directive), _ => unreachable!(), } } // Given a binding and an import directive that resolves to it, // return the corresponding binding defined by the import directive. pub fn import(&self, binding: &'a NameBinding<'a>, directive: &'a ImportDirective<'a>) -> &'a NameBinding<'a> { let vis = if binding.pseudo_vis().is_at_least(directive.vis.get(), self) || // c.f. `PUB_USE_OF_PRIVATE_EXTERN_CRATE` !directive.is_glob() && binding.is_extern_crate() { directive.vis.get() } else { binding.pseudo_vis() }; if let GlobImport { ref max_vis, .. } = directive.subclass { if vis == directive.vis.get() || vis.is_at_least(max_vis.get(), self) { max_vis.set(vis) } } self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Import { binding, directive, used: Cell::new(false), legacy_self_import: false, }, span: directive.span, vis, expansion: directive.expansion, }) } // Define the name or return the existing binding if there is a collision. pub fn try_define(&mut self, module: Module<'a>, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>) -> Result<(), &'a NameBinding<'a>> { self.update_resolution(module, ident, ns, |this, resolution| { if let Some(old_binding) = resolution.binding { if binding.is_glob_import() { if !old_binding.is_glob_import() && !(ns == MacroNS && old_binding.expansion != Mark::root()) { resolution.shadows_glob = Some(binding); } else if binding.def() != old_binding.def() { resolution.binding = Some(this.ambiguity(old_binding, binding)); } else if !old_binding.vis.is_at_least(binding.vis, &*this) { // We are glob-importing the same item but with greater visibility. resolution.binding = Some(binding); } } else if old_binding.is_glob_import() { if ns == MacroNS && binding.expansion != Mark::root() && binding.def() != old_binding.def() { resolution.binding = Some(this.ambiguity(binding, old_binding)); } else { resolution.binding = Some(binding); resolution.shadows_glob = Some(old_binding); } } else { return Err(old_binding); } } else { resolution.binding = Some(binding); } Ok(()) }) } pub fn ambiguity(&self, b1: &'a NameBinding<'a>, b2: &'a NameBinding<'a>) -> &'a NameBinding<'a> { self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Ambiguity { b1: b1, b2: b2, legacy: false }, vis: if b1.vis.is_at_least(b2.vis, self) { b1.vis } else { b2.vis }, span: b1.span, expansion: Mark::root(), }) } // Use `f` to mutate the resolution of the name in the module. // If the resolution becomes a success, define it in the module's glob importers. fn update_resolution(&mut self, module: Module<'a>, ident: Ident, ns: Namespace, f: F) -> T where F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T { // Ensure that `resolution` isn't borrowed when defining in the module's glob importers, // during which the resolution might end up getting re-defined via a glob cycle. let (binding, t) = { let resolution = &mut *self.resolution(module, ident, ns).borrow_mut(); let old_binding = resolution.binding(); let t = f(self, resolution); match resolution.binding() { _ if old_binding.is_some() => return t, None => return t, Some(binding) => match old_binding { Some(old_binding) if old_binding as *const _ == binding as *const _ => return t, _ => (binding, t), } } }; // Define `binding` in `module`s glob importers. for directive in module.glob_importers.borrow_mut().iter() { let mut ident = ident.modern(); let scope = match ident.ctxt.reverse_glob_adjust(module.expansion, directive.span.ctxt().modern()) { Some(Some(def)) => self.macro_def_scope(def), Some(None) => directive.parent, None => continue, }; if self.is_accessible_from(binding.vis, scope) { let imported_binding = self.import(binding, directive); let _ = self.try_define(directive.parent, ident, ns, imported_binding); } } t } // Define a "dummy" resolution containing a Def::Err as a placeholder for a // failed resolution fn import_dummy_binding(&mut self, directive: &'a ImportDirective<'a>) { if let SingleImport { target, .. } = directive.subclass { let dummy_binding = self.dummy_binding; let dummy_binding = self.import(dummy_binding, directive); self.per_ns(|this, ns| { let _ = this.try_define(directive.parent, target, ns, dummy_binding); }); } } } pub struct ImportResolver<'a, 'b: 'a> { pub resolver: &'a mut Resolver<'b>, } impl<'a, 'b: 'a> ::std::ops::Deref for ImportResolver<'a, 'b> { type Target = Resolver<'b>; fn deref(&self) -> &Resolver<'b> { self.resolver } } impl<'a, 'b: 'a> ::std::ops::DerefMut for ImportResolver<'a, 'b> { fn deref_mut(&mut self) -> &mut Resolver<'b> { self.resolver } } impl<'a, 'b: 'a> ty::DefIdTree for &'a ImportResolver<'a, 'b> { fn parent(self, id: DefId) -> Option { self.resolver.parent(id) } } impl<'a, 'b:'a> ImportResolver<'a, 'b> { // Import resolution // // This is a fixed-point algorithm. We resolve imports until our efforts // are stymied by an unresolved import; then we bail out of the current // module and continue. We terminate successfully once no more imports // remain or unsuccessfully when no forward progress in resolving imports // is made. /// Resolves all imports for the crate. This method performs the fixed- /// point iteration. pub fn resolve_imports(&mut self) { let mut prev_num_indeterminates = self.indeterminate_imports.len() + 1; while self.indeterminate_imports.len() < prev_num_indeterminates { prev_num_indeterminates = self.indeterminate_imports.len(); for import in mem::replace(&mut self.indeterminate_imports, Vec::new()) { match self.resolve_import(&import) { true => self.determined_imports.push(import), false => self.indeterminate_imports.push(import), } } } } pub fn finalize_imports(&mut self) { for module in self.arenas.local_modules().iter() { self.finalize_resolutions_in(module); } let mut errors = false; let mut seen_spans = FxHashSet(); for i in 0 .. self.determined_imports.len() { let import = self.determined_imports[i]; if let Some((span, err)) = self.finalize_import(import) { errors = true; if let SingleImport { source, ref result, .. } = import.subclass { if source.name == "self" { // Silence `unresolved import` error if E0429 is already emitted match result.value_ns.get() { Err(Determined) => continue, _ => {}, } } } // If the error is a single failed import then create a "fake" import // resolution for it so that later resolve stages won't complain. self.import_dummy_binding(import); if !seen_spans.contains(&span) { let path = import_path_to_string(&import.module_path[..], &import.subclass, span); let error = ResolutionError::UnresolvedImport(Some((span, &path, &err))); resolve_error(self.resolver, span, error); seen_spans.insert(span); } } } // Report unresolved imports only if no hard error was already reported // to avoid generating multiple errors on the same import. if !errors { if let Some(import) = self.indeterminate_imports.iter().next() { let error = ResolutionError::UnresolvedImport(None); resolve_error(self.resolver, import.span, error); } } } /// Attempts to resolve the given import, returning true if its resolution is determined. /// If successful, the resolved bindings are written into the module. fn resolve_import(&mut self, directive: &'b ImportDirective<'b>) -> bool { debug!("(resolving import for module) resolving import `{}::...` in `{}`", names_to_string(&directive.module_path[..]), module_to_string(self.current_module).unwrap_or("???".to_string())); self.current_module = directive.parent; let module = if let Some(module) = directive.imported_module.get() { module } else { let vis = directive.vis.get(); // For better failure detection, pretend that the import will not define any names // while resolving its module path. directive.vis.set(ty::Visibility::Invisible); let result = self.resolve_path(&directive.module_path[..], None, false, directive.span); directive.vis.set(vis); match result { PathResult::Module(module) => module, PathResult::Indeterminate => return false, _ => return true, } }; directive.imported_module.set(Some(module)); let (source, target, result, type_ns_only) = match directive.subclass { SingleImport { source, target, ref result, type_ns_only } => (source, target, result, type_ns_only), GlobImport { .. } => { self.resolve_glob_import(directive); return true; } _ => unreachable!(), }; let mut indeterminate = false; self.per_ns(|this, ns| if !type_ns_only || ns == TypeNS { if let Err(Undetermined) = result[ns].get() { result[ns].set(this.resolve_ident_in_module(module, source, ns, false, false, directive.span)); } else { return }; let parent = directive.parent; match result[ns].get() { Err(Undetermined) => indeterminate = true, Err(Determined) => { this.update_resolution(parent, target, ns, |_, resolution| { resolution.single_imports.directive_failed() }); } Ok(binding) if !binding.is_importable() => { let msg = format!("`{}` is not directly importable", target); struct_span_err!(this.session, directive.span, E0253, "{}", &msg) .span_label(directive.span, "cannot be imported directly") .emit(); // Do not import this illegal binding. Import a dummy binding and pretend // everything is fine this.import_dummy_binding(directive); } Ok(binding) => { let imported_binding = this.import(binding, directive); let conflict = this.try_define(parent, target, ns, imported_binding); if let Err(old_binding) = conflict { this.report_conflict(parent, target, ns, imported_binding, old_binding); } } } }); !indeterminate } // If appropriate, returns an error to report. fn finalize_import(&mut self, directive: &'b ImportDirective<'b>) -> Option<(Span, String)> { self.current_module = directive.parent; let ImportDirective { ref module_path, span, .. } = *directive; // FIXME: Last path segment is treated specially in import resolution, so extern crate // mode for absolute paths needs some special support for single-segment imports. if module_path.len() == 1 && (module_path[0].node.name == keywords::CrateRoot.name() || module_path[0].node.name == keywords::Extern.name()) { let is_extern = module_path[0].node.name == keywords::Extern.name() || self.session.features_untracked().extern_absolute_paths; match directive.subclass { GlobImport { .. } if is_extern => { return Some((directive.span, "cannot glob-import all possible crates".to_string())); } SingleImport { source, target, .. } => { let crate_root = if source.name == keywords::Crate.name() && module_path[0].node.name != keywords::Extern.name() { if target.name == keywords::Crate.name() { return Some((directive.span, "crate root imports need to be explicitly named: \ `use crate as name;`".to_string())); } else { Some(self.resolve_crate_root(source.ctxt.modern(), false)) } } else if is_extern && !token::Ident(source).is_path_segment_keyword() { let crate_id = self.crate_loader.resolve_crate_from_path(source.name, directive.span); let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX }); self.populate_module_if_necessary(crate_root); Some(crate_root) } else { None }; if let Some(crate_root) = crate_root { let binding = (crate_root, ty::Visibility::Public, directive.span, directive.expansion).to_name_binding(self.arenas); let binding = self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Import { binding, directive, used: Cell::new(false), legacy_self_import: false, }, vis: directive.vis.get(), span: directive.span, expansion: directive.expansion, }); let _ = self.try_define(directive.parent, target, TypeNS, binding); return None; } } _ => {} } } let module_result = self.resolve_path(&module_path, None, true, span); let module = match module_result { PathResult::Module(module) => module, PathResult::Failed(span, msg, false) => { resolve_error(self, span, ResolutionError::FailedToResolve(&msg)); return None; } PathResult::Failed(span, msg, true) => { let (mut self_path, mut self_result) = (module_path.clone(), None); if !self_path.is_empty() && !token::Ident(self_path[0].node).is_path_segment_keyword() && !(self_path.len() > 1 && token::Ident(self_path[1].node).is_path_segment_keyword()) { self_path[0].node.name = keywords::SelfValue.name(); self_result = Some(self.resolve_path(&self_path, None, false, span)); } return if let Some(PathResult::Module(..)) = self_result { Some((span, format!("Did you mean `{}`?", names_to_string(&self_path[..])))) } else { Some((span, msg)) }; }, _ => return None, }; let (ident, result, type_ns_only) = match directive.subclass { SingleImport { source, ref result, type_ns_only, .. } => (source, result, type_ns_only), GlobImport { .. } if module.def_id() == directive.parent.def_id() => { // Importing a module into itself is not allowed. return Some((directive.span, "Cannot glob-import a module into itself.".to_string())); } GlobImport { is_prelude, ref max_vis } => { if !is_prelude && max_vis.get() != ty::Visibility::Invisible && // Allow empty globs. !max_vis.get().is_at_least(directive.vis.get(), &*self) { let msg = "A non-empty glob must import something with the glob's visibility"; self.session.span_err(directive.span, msg); } return None; } _ => unreachable!(), }; let mut all_ns_err = true; let mut legacy_self_import = None; self.per_ns(|this, ns| if !type_ns_only || ns == TypeNS { if let Ok(binding) = result[ns].get() { all_ns_err = false; if this.record_use(ident, ns, binding, directive.span) { this.resolution(module, ident, ns).borrow_mut().binding = Some(this.dummy_binding); } } } else if let Ok(binding) = this.resolve_ident_in_module(module, ident, ns, false, false, directive.span) { legacy_self_import = Some(directive); let binding = this.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Import { binding, directive, used: Cell::new(false), legacy_self_import: true, }, ..*binding }); let _ = this.try_define(directive.parent, ident, ns, binding); }); if all_ns_err { if let Some(directive) = legacy_self_import { self.warn_legacy_self_import(directive); return None; } let mut all_ns_failed = true; self.per_ns(|this, ns| if !type_ns_only || ns == TypeNS { match this.resolve_ident_in_module(module, ident, ns, false, true, span) { Ok(_) => all_ns_failed = false, _ => {} } }); return if all_ns_failed { let resolutions = module.resolutions.borrow(); let names = resolutions.iter().filter_map(|(&(ref i, _), resolution)| { if *i == ident { return None; } // Never suggest the same name match *resolution.borrow() { NameResolution { binding: Some(name_binding), .. } => { match name_binding.kind { NameBindingKind::Import { binding, .. } => { match binding.kind { // Never suggest the name that has binding error // i.e. the name that cannot be previously resolved NameBindingKind::Def(Def::Err) => return None, _ => Some(&i.name), } }, _ => Some(&i.name), } }, NameResolution { single_imports: SingleImports::None, .. } => None, _ => Some(&i.name), } }); let lev_suggestion = match find_best_match_for_name(names, &ident.name.as_str(), None) { Some(name) => format!(". Did you mean to use `{}`?", name), None => "".to_owned(), }; let module_str = module_to_string(module); let msg = if let Some(module_str) = module_str { format!("no `{}` in `{}`{}", ident, module_str, lev_suggestion) } else { format!("no `{}` in the root{}", ident, lev_suggestion) }; Some((span, msg)) } else { // `resolve_ident_in_module` reported a privacy error. self.import_dummy_binding(directive); None } } let mut reexport_error = None; let mut any_successful_reexport = false; self.per_ns(|this, ns| { if let Ok(binding) = result[ns].get() { let vis = directive.vis.get(); if !binding.pseudo_vis().is_at_least(vis, &*this) { reexport_error = Some((ns, binding)); } else { any_successful_reexport = true; } } }); // All namespaces must be re-exported with extra visibility for an error to occur. if !any_successful_reexport { let (ns, binding) = reexport_error.unwrap(); if ns == TypeNS && binding.is_extern_crate() { let msg = format!("extern crate `{}` is private, and cannot be \ re-exported (error E0365), consider declaring with \ `pub`", ident); self.session.buffer_lint(PUB_USE_OF_PRIVATE_EXTERN_CRATE, directive.id, directive.span, &msg); } else if ns == TypeNS { struct_span_err!(self.session, directive.span, E0365, "`{}` is private, and cannot be re-exported", ident) .span_label(directive.span, format!("re-export of private `{}`", ident)) .note(&format!("consider declaring type or module `{}` with `pub`", ident)) .emit(); } else { let msg = format!("`{}` is private, and cannot be re-exported", ident); let note_msg = format!("consider marking `{}` as `pub` in the imported module", ident); struct_span_err!(self.session, directive.span, E0364, "{}", &msg) .span_note(directive.span, ¬e_msg) .emit(); } } // Record what this import resolves to for later uses in documentation, // this may resolve to either a value or a type, but for documentation // purposes it's good enough to just favor one over the other. self.per_ns(|this, ns| if let Some(binding) = result[ns].get().ok() { this.def_map.entry(directive.id).or_insert(PathResolution::new(binding.def())); }); debug!("(resolving single import) successfully resolved import"); None } fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) { let module = directive.imported_module.get().unwrap(); self.populate_module_if_necessary(module); if let Some(Def::Trait(_)) = module.def() { self.session.span_err(directive.span, "items in traits are not importable."); return; } else if module.def_id() == directive.parent.def_id() { return; } else if let GlobImport { is_prelude: true, .. } = directive.subclass { self.prelude = Some(module); return; } // Add to module's glob_importers module.glob_importers.borrow_mut().push(directive); // Ensure that `resolutions` isn't borrowed during `try_define`, // since it might get updated via a glob cycle. let bindings = module.resolutions.borrow().iter().filter_map(|(&ident, resolution)| { resolution.borrow().binding().map(|binding| (ident, binding)) }).collect::>(); for ((mut ident, ns), binding) in bindings { let scope = match ident.ctxt.reverse_glob_adjust(module.expansion, directive.span.ctxt().modern()) { Some(Some(def)) => self.macro_def_scope(def), Some(None) => self.current_module, None => continue, }; if self.is_accessible_from(binding.pseudo_vis(), scope) { let imported_binding = self.import(binding, directive); let _ = self.try_define(directive.parent, ident, ns, imported_binding); } } // Record the destination of this import self.record_def(directive.id, PathResolution::new(module.def().unwrap())); } // Miscellaneous post-processing, including recording re-exports, // reporting conflicts, and reporting unresolved imports. fn finalize_resolutions_in(&mut self, module: Module<'b>) { // Since import resolution is finished, globs will not define any more names. *module.globs.borrow_mut() = Vec::new(); let mut reexports = Vec::new(); let mut exported_macro_names = FxHashMap(); if module as *const _ == self.graph_root as *const _ { let macro_exports = mem::replace(&mut self.macro_exports, Vec::new()); for export in macro_exports.into_iter().rev() { if exported_macro_names.insert(export.ident.modern(), export.span).is_none() { reexports.push(export); } } } for (&(ident, ns), resolution) in module.resolutions.borrow().iter() { let resolution = &mut *resolution.borrow_mut(); let binding = match resolution.binding { Some(binding) => binding, None => continue, }; if binding.is_import() || binding.is_macro_def() { let def = binding.def(); if def != Def::Err { if !def.def_id().is_local() { self.cstore.export_macros_untracked(def.def_id().krate); } if let Def::Macro(..) = def { if let Some(&span) = exported_macro_names.get(&ident.modern()) { let msg = format!("a macro named `{}` has already been exported", ident); self.session.struct_span_err(span, &msg) .span_label(span, format!("`{}` already exported", ident)) .span_note(binding.span, "previous macro export here") .emit(); } } reexports.push(Export { ident: ident.modern(), def: def, span: binding.span, vis: binding.vis, is_import: true, }); } } match binding.kind { NameBindingKind::Import { binding: orig_binding, directive, .. } => { if ns == TypeNS && orig_binding.is_variant() && !orig_binding.vis.is_at_least(binding.vis, &*self) { let msg = match directive.subclass { ImportDirectiveSubclass::SingleImport { .. } => { format!("variant `{}` is private and cannot be re-exported", ident) }, ImportDirectiveSubclass::GlobImport { .. } => { let msg = "enum is private and its variants \ cannot be re-exported".to_owned(); let error_id = (DiagnosticMessageId::ErrorId(0), // no code?! Some(binding.span), msg.clone()); let fresh = self.session.one_time_diagnostics .borrow_mut().insert(error_id); if !fresh { continue; } msg }, ref s @ _ => bug!("unexpected import subclass {:?}", s) }; let mut err = self.session.struct_span_err(binding.span, &msg); let imported_module = directive.imported_module.get() .expect("module should exist"); let resolutions = imported_module.parent.expect("parent should exist") .resolutions.borrow(); let enum_path_segment_index = directive.module_path.len() - 1; let enum_ident = directive.module_path[enum_path_segment_index].node; let enum_resolution = resolutions.get(&(enum_ident, TypeNS)) .expect("resolution should exist"); let enum_span = enum_resolution.borrow() .binding.expect("binding should exist") .span; let enum_def_span = self.session.codemap().def_span(enum_span); let enum_def_snippet = self.session.codemap() .span_to_snippet(enum_def_span).expect("snippet should exist"); // potentially need to strip extant `crate`/`pub(path)` for suggestion let after_vis_index = enum_def_snippet.find("enum") .expect("`enum` keyword should exist in snippet"); let suggestion = format!("pub {}", &enum_def_snippet[after_vis_index..]); self.session .diag_span_suggestion_once(&mut err, DiagnosticMessageId::ErrorId(0), enum_def_span, "consider making the enum public", suggestion); err.emit(); } } NameBindingKind::Ambiguity { b1, b2, .. } if b1.is_glob_import() && b2.is_glob_import() => { let (orig_b1, orig_b2) = match (&b1.kind, &b2.kind) { (&NameBindingKind::Import { binding: b1, .. }, &NameBindingKind::Import { binding: b2, .. }) => (b1, b2), _ => continue, }; let (b1, b2) = match (orig_b1.vis, orig_b2.vis) { (ty::Visibility::Public, ty::Visibility::Public) => continue, (ty::Visibility::Public, _) => (b1, b2), (_, ty::Visibility::Public) => (b2, b1), _ => continue, }; resolution.binding = Some(self.arenas.alloc_name_binding(NameBinding { kind: NameBindingKind::Ambiguity { b1: b1, b2: b2, legacy: true }, ..*b1 })); } _ => {} } } if reexports.len() > 0 { if let Some(def_id) = module.def_id() { self.export_map.insert(def_id, reexports); } } } } fn import_path_to_string(names: &[SpannedIdent], subclass: &ImportDirectiveSubclass, span: Span) -> String { let pos = names.iter() .position(|p| span == p.span && p.node.name != keywords::CrateRoot.name()); let global = !names.is_empty() && names[0].node.name == keywords::CrateRoot.name(); if let Some(pos) = pos { let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] }; names_to_string(names) } else { let names = if global { &names[1..] } else { names }; if names.is_empty() { import_directive_subclass_to_string(subclass) } else { // FIXME: Remove this entire logic after #48116 is fixed. // // Note that this code looks a little wonky, it's currently here to // hopefully help debug #48116, but otherwise isn't intended to // cause any problems. let x = format!( "{}::{}", names_to_string(names), import_directive_subclass_to_string(subclass), ); if names.is_empty() || x.starts_with("::") { span_bug!( span, "invalid name `{}` at {:?}; global = {}, names = {:?}, subclass = {:?}", x, span, global, names, subclass ); } return x } } } fn import_directive_subclass_to_string(subclass: &ImportDirectiveSubclass) -> String { match *subclass { SingleImport { source, .. } => source.to_string(), GlobImport { .. } => "*".to_string(), ExternCrate(_) => "".to_string(), MacroUse => "#[macro_use]".to_string(), } }