//! A bunch of methods and structures more or less related to resolving imports. use ImportDirectiveSubclass::*; use crate::diagnostics::Suggestion; use crate::Determinacy::{self, *}; use crate::Namespace::{self, MacroNS, TypeNS}; use crate::{module_to_string, names_to_string}; use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind}; use crate::{BindingKey, ModuleKind, ResolutionError, Resolver, Segment}; use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet, Weak}; use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding}; use rustc::hir::exports::Export; use rustc::lint::builtin::BuiltinLintDiagnostics; use rustc::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS}; use rustc::session::DiagnosticMessageId; use rustc::ty; use rustc::{bug, span_bug}; use rustc_data_structures::fx::FxHashSet; use rustc_data_structures::ptr_key::PtrKey; use rustc_errors::{pluralize, struct_span_err, Applicability}; use rustc_hir::def::{self, PartialRes}; use rustc_hir::def_id::DefId; use rustc_span::hygiene::ExpnId; use rustc_span::symbol::kw; use rustc_span::{MultiSpan, Span}; use syntax::ast::{Ident, Name, NodeId}; use syntax::unwrap_or; use syntax::util::lev_distance::find_best_match_for_name; use rustc_error_codes::*; use log::*; use std::cell::Cell; use std::{mem, ptr}; type Res = def::Res; /// Contains data for specific types of import directives. #[derive(Clone, Debug)] pub enum ImportDirectiveSubclass<'a> { SingleImport { /// `source` in `use prefix::source as target`. source: Ident, /// `target` in `use prefix::source as target`. target: Ident, /// Bindings to which `source` refers to. source_bindings: PerNS, Determinacy>>>, /// Bindings introduced by `target`. target_bindings: PerNS>>>, /// `true` for `...::{self [as target]}` imports, `false` otherwise. type_ns_only: bool, /// Did this import result from a nested import? ie. `use foo::{bar, baz};` nested: 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 { source: Option, target: Ident, }, MacroUse, } /// One import directive. #[derive(Debug, Clone)] crate struct ImportDirective<'a> { /// The ID of the `extern crate`, `UseTree` etc that imported this `ImportDirective`. /// /// In the case where the `ImportDirective` was expanded from a "nested" use tree, /// this id is the ID of the leaf tree. For example: /// /// ```ignore (pacify the mercilous tidy) /// use foo::bar::{a, b} /// ``` /// /// If this is the import directive for `foo::bar::a`, we would have the ID of the `UseTree` /// for `a` in this field. pub id: NodeId, /// The `id` of the "root" use-kind -- this is always the same as /// `id` except in the case of "nested" use trees, in which case /// it will be the `id` of the root use tree. e.g., in the example /// from `id`, this would be the ID of the `use foo::bar` /// `UseTree` node. pub root_id: NodeId, /// Span of the entire use statement. pub use_span: Span, /// Span of the entire use statement with attributes. pub use_span_with_attributes: Span, /// Did the use statement have any attributes? pub has_attributes: bool, /// Span of this use tree. pub span: Span, /// Span of the *root* use tree (see `root_id`). pub root_span: Span, pub parent_scope: ParentScope<'a>, pub module_path: Vec, /// The resolution of `module_path`. pub imported_module: Cell>>, pub subclass: ImportDirectiveSubclass<'a>, pub vis: Cell, pub used: Cell, } impl<'a> ImportDirective<'a> { pub fn is_glob(&self) -> bool { match self.subclass { ImportDirectiveSubclass::GlobImport { .. } => true, _ => false, } } pub fn is_nested(&self) -> bool { match self.subclass { ImportDirectiveSubclass::SingleImport { nested, .. } => nested, _ => false, } } crate fn crate_lint(&self) -> CrateLint { CrateLint::UsePath { root_id: self.root_id, root_span: self.root_span } } } #[derive(Clone, Default, Debug)] /// Records information about the resolution of a name in a namespace of a module. pub struct NameResolution<'a> { /// Single imports that may define the name in the namespace. /// Import directives are arena-allocated, so it's ok to use pointers as keys. single_imports: FxHashSet>>, /// The least shadowable known binding for this name, or None if there are no known bindings. pub binding: Option<&'a NameBinding<'a>>, shadowed_glob: Option<&'a NameBinding<'a>>, } impl<'a> NameResolution<'a> { // Returns the binding for the name if it is known or None if it not known. pub(crate) fn binding(&self) -> Option<&'a NameBinding<'a>> { self.binding.and_then(|binding| { if !binding.is_glob_import() || self.single_imports.is_empty() { Some(binding) } else { None } }) } crate fn add_single_import(&mut self, directive: &'a ImportDirective<'a>) { self.single_imports.insert(PtrKey(directive)); } } impl<'a> Resolver<'a> { crate fn resolve_ident_in_module_unadjusted( &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_unadjusted_ext( module, ident, ns, parent_scope, false, record_used, path_span, ) .map_err(|(determinacy, _)| determinacy) } /// Attempts to resolve `ident` in namespaces `ns` of `module`. /// Invariant: if `record_used` is `Some`, expansion and import resolution must be complete. crate fn resolve_ident_in_module_unadjusted_ext( &mut self, module: ModuleOrUniformRoot<'a>, ident: Ident, ns: Namespace, parent_scope: &ParentScope<'a>, restricted_shadowing: bool, record_used: bool, path_span: Span, ) -> Result<&'a NameBinding<'a>, (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, record_used, record_used, path_span, ); 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, !record_used) { 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, ty::Visibility::Public, module.span, ExpnId::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 scopes = ScopeSet::All(ns, true); let binding = self.early_resolve_ident_in_lexical_scope( ident, scopes, parent_scope, record_used, record_used, path_span, ); return binding.map_err(|determinacy| (determinacy, Weak::No)); } }; let key = self.new_key(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 let Some(binding) = resolution.binding { if !restricted_shadowing && binding.expansion != ExpnId::root() { if let NameBindingKind::Res(_, true) = binding.kind { self.macro_expanded_macro_export_errors.insert((path_span, binding.span)); } } } let check_usable = |this: &mut Self, binding: &'a NameBinding<'a>| { if let Some(blacklisted_binding) = this.blacklisted_binding { if ptr::eq(binding, blacklisted_binding) { return Err((Determined, Weak::No)); } } // `extern crate` are always usable for backwards compatibility, see issue #37020, // remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`. let usable = this.is_accessible_from(binding.vis, parent_scope.module) || binding.is_extern_crate(); if usable { Ok(binding) } else { Err((Determined, Weak::No)) } }; if record_used { return resolution .binding .and_then(|binding| { // If the primary binding is blacklisted, 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. if let Some(blacklisted_binding) = self.blacklisted_binding { if ptr::eq(binding, blacklisted_binding) { return resolution.shadowed_glob; } } Some(binding) }) .ok_or((Determined, Weak::No)) .and_then(|binding| { if self.last_import_segment && check_usable(self, binding).is_err() { Err((Determined, Weak::No)) } else { self.record_use(ident, ns, binding, restricted_shadowing); if let Some(shadowed_glob) = resolution.shadowed_glob { // Forbid expanded shadowing to avoid time travel. if restricted_shadowing && binding.expansion != ExpnId::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 !self.is_accessible_from(binding.vis, parent_scope.module) && // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE` !(self.last_import_segment && binding.is_extern_crate()) { self.privacy_errors.push(PrivacyError(path_span, ident, binding)); } Ok(binding) } }); } // Items and single imports are not shadowable, if we have one, then it's determined. if let Some(binding) = resolution.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 { if !self.is_accessible_from(single_import.vis.get(), parent_scope.module) { continue; } let module = unwrap_or!( single_import.imported_module.get(), return Err((Undetermined, Weak::No)) ); let ident = match single_import.subclass { SingleImport { source, .. } => source, _ => unreachable!(), }; match self.resolve_ident_in_module( module, ident, ns, &single_import.parent_scope, false, path_span, ) { 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) = resolution.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() { if !self.is_accessible_from(glob_import.vis.get(), 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.modern()); match ident.span.glob_adjust(module.expansion, glob_import.span) { Some(Some(def)) => { tmp_parent_scope = ParentScope { module: self.macro_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, false, path_span, ); 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)) } // Given a binding and an import directive that resolves to it, // return the corresponding binding defined by the import directive. crate 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) || // cf. `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) }, ambiguity: None, span: directive.span, vis, expansion: directive.parent_scope.expansion, }) } // Define the name or return the existing binding if there is a collision. crate fn try_define( &mut self, module: Module<'a>, key: BindingKey, binding: &'a NameBinding<'a>, ) -> Result<(), &'a NameBinding<'a>> { let res = binding.res(); self.check_reserved_macro_name(key.ident, res); self.set_binding_parent_module(binding, module); self.update_resolution(module, key, |this, resolution| { if let Some(old_binding) = resolution.binding { if res == Res::Err { // Do not override real bindings with `Res::Err`s from error recovery. return Ok(()); } match (old_binding.is_glob_import(), binding.is_glob_import()) { (true, true) => { if res != old_binding.res() { resolution.binding = Some(this.ambiguity( AmbiguityKind::GlobVsGlob, 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); } } (old_glob @ true, false) | (old_glob @ false, true) => { let (glob_binding, nonglob_binding) = if old_glob { (old_binding, binding) } else { (binding, old_binding) }; if glob_binding.res() != nonglob_binding.res() && key.ns == MacroNS && nonglob_binding.expansion != ExpnId::root() { resolution.binding = Some(this.ambiguity( AmbiguityKind::GlobVsExpanded, nonglob_binding, glob_binding, )); } else { resolution.binding = Some(nonglob_binding); } resolution.shadowed_glob = Some(glob_binding); } (false, false) => { return Err(old_binding); } } } else { resolution.binding = Some(binding); } Ok(()) }) } fn ambiguity( &self, kind: AmbiguityKind, primary_binding: &'a NameBinding<'a>, secondary_binding: &'a NameBinding<'a>, ) -> &'a NameBinding<'a> { self.arenas.alloc_name_binding(NameBinding { ambiguity: Some((secondary_binding, kind)), ..primary_binding.clone() }) } // 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>, key: BindingKey, 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, key).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 ptr::eq(old_binding, binding) => return t, _ => (binding, t), }, } }; // Define `binding` in `module`s glob importers. for directive in module.glob_importers.borrow_mut().iter() { let mut ident = key.ident; let scope = match ident.span.reverse_glob_adjust(module.expansion, directive.span) { Some(Some(def)) => self.macro_def_scope(def), Some(None) => directive.parent_scope.module, None => continue, }; if self.is_accessible_from(binding.vis, scope) { let imported_binding = self.import(binding, directive); let key = BindingKey { ident, ..key }; let _ = self.try_define(directive.parent_scope.module, key, imported_binding); } } t } // Define a "dummy" resolution containing a Res::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 key = this.new_key(target, ns); let _ = this.try_define(directive.parent_scope.module, key, dummy_binding); // Consider erroneous imports used to avoid duplicate diagnostics. this.record_use(target, ns, dummy_binding, false); }); } } } /// An error that may be transformed into a diagnostic later. Used to combine multiple unresolved /// import errors within the same use tree into a single diagnostic. #[derive(Debug, Clone)] struct UnresolvedImportError { span: Span, label: Option, note: Vec, suggestion: Option, } pub struct ImportResolver<'a, 'b> { pub r: &'a mut Resolver<'b>, } impl<'a, 'b> ty::DefIdTree for &'a ImportResolver<'a, 'b> { fn parent(self, id: DefId) -> Option { self.r.parent(id) } } impl<'a, 'b> 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.r.indeterminate_imports.len() + 1; while self.r.indeterminate_imports.len() < prev_num_indeterminates { prev_num_indeterminates = self.r.indeterminate_imports.len(); for import in mem::take(&mut self.r.indeterminate_imports) { match self.resolve_import(&import) { true => self.r.determined_imports.push(import), false => self.r.indeterminate_imports.push(import), } } } } pub fn finalize_imports(&mut self) { for module in self.r.arenas.local_modules().iter() { self.finalize_resolutions_in(module); } let mut seen_spans = FxHashSet::default(); let mut errors = vec![]; let mut prev_root_id: NodeId = NodeId::from_u32(0); let determined_imports = mem::take(&mut self.r.determined_imports); let indeterminate_imports = mem::take(&mut self.r.indeterminate_imports); for (is_indeterminate, import) in determined_imports .into_iter() .map(|i| (false, i)) .chain(indeterminate_imports.into_iter().map(|i| (true, i))) { if let Some(err) = self.finalize_import(import) { if let SingleImport { source, ref source_bindings, .. } = import.subclass { if source.name == kw::SelfLower { // Silence `unresolved import` error if E0429 is already emitted if let Err(Determined) = source_bindings.value_ns.get() { 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.r.import_dummy_binding(import); if prev_root_id.as_u32() != 0 && prev_root_id.as_u32() != import.root_id.as_u32() && !errors.is_empty() { // In the case of a new import line, throw a diagnostic message // for the previous line. self.throw_unresolved_import_error(errors, None); errors = vec![]; } if seen_spans.insert(err.span) { let path = import_path_to_string( &import.module_path.iter().map(|seg| seg.ident).collect::>(), &import.subclass, err.span, ); errors.push((path, err)); prev_root_id = import.root_id; } } else if is_indeterminate { // Consider erroneous imports used to avoid duplicate diagnostics. self.r.used_imports.insert((import.id, TypeNS)); let path = import_path_to_string( &import.module_path.iter().map(|seg| seg.ident).collect::>(), &import.subclass, import.span, ); let err = UnresolvedImportError { span: import.span, label: None, note: Vec::new(), suggestion: None, }; errors.push((path, err)); } } if !errors.is_empty() { self.throw_unresolved_import_error(errors.clone(), None); } } fn throw_unresolved_import_error( &self, errors: Vec<(String, UnresolvedImportError)>, span: Option, ) { /// Upper limit on the number of `span_label` messages. const MAX_LABEL_COUNT: usize = 10; let (span, msg) = if errors.is_empty() { (span.unwrap(), "unresolved import".to_string()) } else { let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect()); let paths = errors.iter().map(|(path, _)| format!("`{}`", path)).collect::>(); let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),); (span, msg) }; let mut diag = struct_span_err!(self.r.session, span, E0432, "{}", &msg); if let Some((_, UnresolvedImportError { note, .. })) = errors.iter().last() { for message in note { diag.note(&message); } } for (_, err) in errors.into_iter().take(MAX_LABEL_COUNT) { if let Some(label) = err.label { diag.span_label(err.span, label); } if let Some((suggestions, msg, applicability)) = err.suggestion { diag.multipart_suggestion(&msg, suggestions, applicability); } } diag.emit(); } /// 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 `{}`", Segment::names_to_string(&directive.module_path), module_to_string(directive.parent_scope.module).unwrap_or_else(|| "???".to_string()), ); let module = if let Some(module) = directive.imported_module.get() { module } else { // For better failure detection, pretend that the import will // not define any names while resolving its module path. let orig_vis = directive.vis.replace(ty::Visibility::Invisible); let path_res = self.r.resolve_path( &directive.module_path, None, &directive.parent_scope, false, directive.span, directive.crate_lint(), ); directive.vis.set(orig_vis); match path_res { PathResult::Module(module) => module, PathResult::Indeterminate => return false, PathResult::NonModule(..) | PathResult::Failed { .. } => return true, } }; directive.imported_module.set(Some(module)); let (source, target, source_bindings, target_bindings, type_ns_only) = match directive.subclass { SingleImport { source, target, ref source_bindings, ref target_bindings, type_ns_only, .. } => (source, target, source_bindings, target_bindings, type_ns_only), GlobImport { .. } => { self.resolve_glob_import(directive); return true; } _ => unreachable!(), }; let mut indeterminate = false; self.r.per_ns(|this, ns| { if !type_ns_only || ns == TypeNS { if let Err(Undetermined) = source_bindings[ns].get() { // For better failure detection, pretend that the import will // not define any names while resolving its module path. let orig_vis = directive.vis.replace(ty::Visibility::Invisible); let binding = this.resolve_ident_in_module( module, source, ns, &directive.parent_scope, false, directive.span, ); directive.vis.set(orig_vis); source_bindings[ns].set(binding); } else { return; }; let parent = directive.parent_scope.module; match source_bindings[ns].get() { Err(Undetermined) => indeterminate = true, // Don't update the resolution, because it was never added. Err(Determined) if target.name == kw::Underscore => {} Err(Determined) => { let key = this.new_key(target, ns); this.update_resolution(parent, key, |_, resolution| { resolution.single_imports.remove(&PtrKey(directive)); }); } 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); target_bindings[ns].set(Some(imported_binding)); this.define(parent, target, ns, imported_binding); } } } }); !indeterminate } /// Performs final import resolution, consistency checks and error reporting. /// /// Optionally returns an unresolved import error. This error is buffered and used to /// consolidate multiple unresolved import errors into a single diagnostic. fn finalize_import( &mut self, directive: &'b ImportDirective<'b>, ) -> Option { let orig_vis = directive.vis.replace(ty::Visibility::Invisible); let prev_ambiguity_errors_len = self.r.ambiguity_errors.len(); let path_res = self.r.resolve_path( &directive.module_path, None, &directive.parent_scope, true, directive.span, directive.crate_lint(), ); let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len; directive.vis.set(orig_vis); if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res { // Consider erroneous imports used to avoid duplicate diagnostics. self.r.used_imports.insert((directive.id, TypeNS)); } let module = match path_res { PathResult::Module(module) => { // Consistency checks, analogous to `finalize_macro_resolutions`. if let Some(initial_module) = directive.imported_module.get() { if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity { span_bug!(directive.span, "inconsistent resolution for an import"); } } else { if self.r.privacy_errors.is_empty() { let msg = "cannot determine resolution for the import"; let msg_note = "import resolution is stuck, try simplifying other imports"; self.r.session.struct_span_err(directive.span, msg).note(msg_note).emit(); } } module } PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => { if no_ambiguity { assert!(directive.imported_module.get().is_none()); self.r .report_error(span, ResolutionError::FailedToResolve { label, suggestion }); } return None; } PathResult::Failed { is_error_from_last_segment: true, span, label, suggestion } => { if no_ambiguity { assert!(directive.imported_module.get().is_none()); let err = match self.make_path_suggestion( span, directive.module_path.clone(), &directive.parent_scope, ) { Some((suggestion, note)) => UnresolvedImportError { span, label: None, note, suggestion: Some(( vec![(span, Segment::names_to_string(&suggestion))], String::from("a similar path exists"), Applicability::MaybeIncorrect, )), }, None => UnresolvedImportError { span, label: Some(label), note: Vec::new(), suggestion, }, }; return Some(err); } return None; } PathResult::NonModule(path_res) if path_res.base_res() == Res::Err => { if no_ambiguity { assert!(directive.imported_module.get().is_none()); } // The error was already reported earlier. return None; } PathResult::Indeterminate | PathResult::NonModule(..) => unreachable!(), }; let (ident, target, source_bindings, target_bindings, type_ns_only) = match directive .subclass { SingleImport { source, target, ref source_bindings, ref target_bindings, type_ns_only, .. } => (source, target, source_bindings, target_bindings, type_ns_only), GlobImport { is_prelude, ref max_vis } => { if directive.module_path.len() <= 1 { // HACK(eddyb) `lint_if_path_starts_with_module` needs at least // 2 segments, so the `resolve_path` above won't trigger it. let mut full_path = directive.module_path.clone(); full_path.push(Segment::from_ident(Ident::invalid())); self.r.lint_if_path_starts_with_module( directive.crate_lint(), &full_path, directive.span, None, ); } if let ModuleOrUniformRoot::Module(module) = module { if module.def_id() == directive.parent_scope.module.def_id() { // Importing a module into itself is not allowed. return Some(UnresolvedImportError { span: directive.span, label: Some(String::from("cannot glob-import a module into itself")), note: Vec::new(), suggestion: None, }); } } if !is_prelude && max_vis.get() != ty::Visibility::Invisible && // Allow empty globs. !max_vis.get().is_at_least(directive.vis.get(), &*self) { let msg = "glob import doesn't reexport anything because no candidate is public enough"; self.r.lint_buffer.buffer_lint( UNUSED_IMPORTS, directive.id, directive.span, msg, ); } return None; } _ => unreachable!(), }; let mut all_ns_err = true; self.r.per_ns(|this, ns| { if !type_ns_only || ns == TypeNS { let orig_vis = directive.vis.replace(ty::Visibility::Invisible); let orig_blacklisted_binding = mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get()); let orig_last_import_segment = mem::replace(&mut this.last_import_segment, true); let binding = this.resolve_ident_in_module( module, ident, ns, &directive.parent_scope, true, directive.span, ); this.last_import_segment = orig_last_import_segment; this.blacklisted_binding = orig_blacklisted_binding; directive.vis.set(orig_vis); match binding { Ok(binding) => { // Consistency checks, analogous to `finalize_macro_resolutions`. let initial_res = source_bindings[ns].get().map(|initial_binding| { all_ns_err = false; if let Some(target_binding) = target_bindings[ns].get() { // Note that as_str() de-gensyms the Symbol if target.name.as_str() == "_" && initial_binding.is_extern_crate() && !initial_binding.is_import() { this.record_use( ident, ns, target_binding, directive.module_path.is_empty(), ); } } initial_binding.res() }); let res = binding.res(); if let Ok(initial_res) = initial_res { if res != initial_res && this.ambiguity_errors.is_empty() { span_bug!(directive.span, "inconsistent resolution for an import"); } } else { if res != Res::Err && this.ambiguity_errors.is_empty() && this.privacy_errors.is_empty() { let msg = "cannot determine resolution for the import"; let msg_note = "import resolution is stuck, try simplifying other imports"; this.session .struct_span_err(directive.span, msg) .note(msg_note) .emit(); } } } Err(..) => { // FIXME: This assert may fire if public glob is later shadowed by a private // single import (see test `issue-55884-2.rs`). In theory single imports should // always block globs, even if they are not yet resolved, so that this kind of // self-inconsistent resolution never happens. // Reenable the assert when the issue is fixed. // assert!(result[ns].get().is_err()); } } } }); if all_ns_err { let mut all_ns_failed = true; self.r.per_ns(|this, ns| { if !type_ns_only || ns == TypeNS { let binding = this.resolve_ident_in_module( module, ident, ns, &directive.parent_scope, true, directive.span, ); if binding.is_ok() { all_ns_failed = false; } } }); return if all_ns_failed { let resolutions = match module { ModuleOrUniformRoot::Module(module) => { Some(self.r.resolutions(module).borrow()) } _ => None, }; let resolutions = resolutions.as_ref().into_iter().flat_map(|r| r.iter()); let names = resolutions.filter_map(|(BindingKey { ident: 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::Res(Res::Err, _) => return None, _ => Some(&i.name), } } _ => Some(&i.name), } } NameResolution { ref single_imports, .. } if single_imports.is_empty() => { None } _ => Some(&i.name), } }); let lev_suggestion = find_best_match_for_name(names, &ident.as_str(), None).map(|suggestion| { ( vec![(ident.span, suggestion.to_string())], String::from("a similar name exists in the module"), Applicability::MaybeIncorrect, ) }); let (suggestion, note) = match self.check_for_module_export_macro(directive, module, ident) { Some((suggestion, note)) => (suggestion.or(lev_suggestion), note), _ => (lev_suggestion, Vec::new()), }; let label = match module { ModuleOrUniformRoot::Module(module) => { let module_str = module_to_string(module); if let Some(module_str) = module_str { format!("no `{}` in `{}`", ident, module_str) } else { format!("no `{}` in the root", ident) } } _ => { if !ident.is_path_segment_keyword() { format!("no `{}` external crate", ident) } else { // HACK(eddyb) this shows up for `self` & `super`, which // should work instead - for now keep the same error message. format!("no `{}` in the root", ident) } } }; Some(UnresolvedImportError { span: directive.span, label: Some(label), note, suggestion, }) } else { // `resolve_ident_in_module` reported a privacy error. self.r.import_dummy_binding(directive); None }; } let mut reexport_error = None; let mut any_successful_reexport = false; self.r.per_ns(|this, ns| { if let Ok(binding) = source_bindings[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.r.lint_buffer.buffer_lint( PUB_USE_OF_PRIVATE_EXTERN_CRATE, directive.id, directive.span, &msg, ); } else if ns == TypeNS { struct_span_err!( self.r.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.r.session, directive.span, E0364, "{}", &msg) .span_note(directive.span, ¬e_msg) .emit(); } } if directive.module_path.len() <= 1 { // HACK(eddyb) `lint_if_path_starts_with_module` needs at least // 2 segments, so the `resolve_path` above won't trigger it. let mut full_path = directive.module_path.clone(); full_path.push(Segment::from_ident(ident)); self.r.per_ns(|this, ns| { if let Ok(binding) = source_bindings[ns].get() { this.lint_if_path_starts_with_module( directive.crate_lint(), &full_path, directive.span, Some(binding), ); } }); } // 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.r.per_ns(|this, ns| { if let Some(binding) = source_bindings[ns].get().ok() { this.import_res_map.entry(directive.id).or_default()[ns] = Some(binding.res()); } }); self.check_for_redundant_imports( ident, directive, source_bindings, target_bindings, target, ); debug!("(resolving single import) successfully resolved import"); None } fn check_for_redundant_imports( &mut self, ident: Ident, directive: &'b ImportDirective<'b>, source_bindings: &PerNS, Determinacy>>>, target_bindings: &PerNS>>>, target: Ident, ) { // Skip if the import was produced by a macro. if directive.parent_scope.expansion != ExpnId::root() { return; } // Skip if we are inside a named module (in contrast to an anonymous // module defined by a block). if let ModuleKind::Def(..) = directive.parent_scope.module.kind { return; } let mut is_redundant = PerNS { value_ns: None, type_ns: None, macro_ns: None }; let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None }; self.r.per_ns(|this, ns| { if let Some(binding) = source_bindings[ns].get().ok() { if binding.res() == Res::Err { return; } let orig_blacklisted_binding = mem::replace(&mut this.blacklisted_binding, target_bindings[ns].get()); match this.early_resolve_ident_in_lexical_scope( target, ScopeSet::All(ns, false), &directive.parent_scope, false, false, directive.span, ) { Ok(other_binding) => { is_redundant[ns] = Some( binding.res() == other_binding.res() && !other_binding.is_ambiguity(), ); redundant_span[ns] = Some((other_binding.span, other_binding.is_import())); } Err(_) => is_redundant[ns] = Some(false), } this.blacklisted_binding = orig_blacklisted_binding; } }); if !is_redundant.is_empty() && is_redundant.present_items().all(|is_redundant| is_redundant) { let mut redundant_spans: Vec<_> = redundant_span.present_items().collect(); redundant_spans.sort(); redundant_spans.dedup(); self.r.lint_buffer.buffer_lint_with_diagnostic( UNUSED_IMPORTS, directive.id, directive.span, &format!("the item `{}` is imported redundantly", ident), BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident), ); } } fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) { let module = match directive.imported_module.get().unwrap() { ModuleOrUniformRoot::Module(module) => module, _ => { self.r.session.span_err(directive.span, "cannot glob-import all possible crates"); return; } }; if module.is_trait() { self.r.session.span_err(directive.span, "items in traits are not importable."); return; } else if module.def_id() == directive.parent_scope.module.def_id() { return; } else if let GlobImport { is_prelude: true, .. } = directive.subclass { self.r.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 = self .r .resolutions(module) .borrow() .iter() .filter_map(|(key, resolution)| { resolution.borrow().binding().map(|binding| (*key, binding)) }) .collect::>(); for (mut key, binding) in bindings { let scope = match key.ident.span.reverse_glob_adjust(module.expansion, directive.span) { Some(Some(def)) => self.r.macro_def_scope(def), Some(None) => directive.parent_scope.module, None => continue, }; if self.r.is_accessible_from(binding.pseudo_vis(), scope) { let imported_binding = self.r.import(binding, directive); let _ = self.r.try_define(directive.parent_scope.module, key, imported_binding); } } // Record the destination of this import self.r.record_partial_res(directive.id, PartialRes::new(module.res().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(); module.for_each_child(self.r, |this, ident, ns, binding| { // Filter away ambiguous imports and anything that has def-site // hygiene. // FIXME: Implement actual cross-crate hygiene. let is_good_import = binding.is_import() && !binding.is_ambiguity() && !ident.span.from_expansion(); if is_good_import || binding.is_macro_def() { let res = binding.res(); if res != Res::Err { if let Some(def_id) = res.opt_def_id() { if !def_id.is_local() { this.cstore().export_macros_untracked(def_id.krate); } } reexports.push(Export { ident, res, span: binding.span, vis: binding.vis }); } } if let NameBindingKind::Import { binding: orig_binding, directive, .. } = binding.kind { if ns == TypeNS && orig_binding.is_variant() && !orig_binding.vis.is_at_least(binding.vis, &*this) { 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 = this.session.one_time_diagnostics.borrow_mut().insert(error_id); if !fresh { return; } msg } ref s @ _ => bug!("unexpected import subclass {:?}", s), }; let mut err = this.session.struct_span_err(binding.span, &msg); let imported_module = match directive.imported_module.get() { Some(ModuleOrUniformRoot::Module(module)) => module, _ => bug!("module should exist"), }; let parent_module = imported_module.parent.expect("parent should exist"); let resolutions = this.resolutions(parent_module).borrow(); let enum_path_segment_index = directive.module_path.len() - 1; let enum_ident = directive.module_path[enum_path_segment_index].ident; let key = this.new_key(enum_ident, TypeNS); let enum_resolution = resolutions.get(&key).expect("resolution should exist"); let enum_span = enum_resolution.borrow().binding.expect("binding should exist").span; let enum_def_span = this.session.source_map().def_span(enum_span); let enum_def_snippet = this .session .source_map() .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..]); this.session.diag_span_suggestion_once( &mut err, DiagnosticMessageId::ErrorId(0), enum_def_span, "consider making the enum public", suggestion, ); err.emit(); } } }); if reexports.len() > 0 { if let Some(def_id) = module.def_id() { self.r.export_map.insert(def_id, reexports); } } } } fn import_path_to_string( names: &[Ident], subclass: &ImportDirectiveSubclass<'_>, span: Span, ) -> String { let pos = names.iter().position(|p| span == p.span && p.name != kw::PathRoot); let global = !names.is_empty() && names[0].name == kw::PathRoot; if let Some(pos) = pos { let names = if global { &names[1..pos + 1] } else { &names[..pos + 1] }; names_to_string(&names.iter().map(|ident| ident.name).collect::>()) } else { let names = if global { &names[1..] } else { names }; if names.is_empty() { import_directive_subclass_to_string(subclass) } else { format!( "{}::{}", names_to_string(&names.iter().map(|ident| ident.name).collect::>()), import_directive_subclass_to_string(subclass), ) } } } 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(), } }