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Diffstat (limited to 'compiler/rustc_resolve/src/imports.rs')
| -rw-r--r-- | compiler/rustc_resolve/src/imports.rs | 1505 |
1 files changed, 1505 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs new file mode 100644 index 00000000000..b02fc427d60 --- /dev/null +++ b/compiler/rustc_resolve/src/imports.rs @@ -0,0 +1,1505 @@ +//! A bunch of methods and structures more or less related to resolving imports. + +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_ast::unwrap_or; +use rustc_ast::util::lev_distance::find_best_match_for_name; +use rustc_ast::NodeId; +use rustc_ast_lowering::ResolverAstLowering; +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_middle::hir::exports::Export; +use rustc_middle::ty; +use rustc_middle::{bug, span_bug}; +use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS}; +use rustc_session::lint::BuiltinLintDiagnostics; +use rustc_session::DiagnosticMessageId; +use rustc_span::hygiene::ExpnId; +use rustc_span::symbol::{kw, Ident, Symbol}; +use rustc_span::{MultiSpan, Span}; + +use tracing::*; + +use std::cell::Cell; +use std::{mem, ptr}; + +type Res = def::Res<NodeId>; + +/// Contains data for specific kinds of imports. +#[derive(Clone, Debug)] +pub enum ImportKind<'a> { + Single { + /// `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<Cell<Result<&'a NameBinding<'a>, Determinacy>>>, + /// Bindings introduced by `target`. + target_bindings: PerNS<Cell<Option<&'a NameBinding<'a>>>>, + /// `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, + }, + Glob { + is_prelude: bool, + max_vis: Cell<ty::Visibility>, // 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<Symbol>, + target: Ident, + }, + MacroUse, +} + +/// One import. +#[derive(Debug, Clone)] +crate struct Import<'a> { + pub kind: ImportKind<'a>, + + /// The ID of the `extern crate`, `UseTree` etc that imported this `Import`. + /// + /// In the case where the `Import` 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 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<Segment>, + /// The resolution of `module_path`. + pub imported_module: Cell<Option<ModuleOrUniformRoot<'a>>>, + pub vis: Cell<ty::Visibility>, + pub used: Cell<bool>, +} + +impl<'a> Import<'a> { + pub fn is_glob(&self) -> bool { + match self.kind { + ImportKind::Glob { .. } => true, + _ => false, + } + } + + pub fn is_nested(&self) -> bool { + match self.kind { + ImportKind::Single { 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. + /// Imports are arena-allocated, so it's ok to use pointers as keys. + single_imports: FxHashSet<PtrKey<'a, Import<'a>>>, + /// 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, import: &'a Import<'a>) { + self.single_imports.insert(PtrKey(import)); + } +} + +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(unusable_binding) = this.unusable_binding { + if ptr::eq(binding, unusable_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 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. + if let Some(unusable_binding) = self.unusable_binding { + if ptr::eq(binding, unusable_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 { + ident, + binding, + dedup_span: path_span, + }); + } + + 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.kind { + ImportKind::Single { 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.normalize_to_macros_2_0()); + 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 that resolves to it, + // return the corresponding binding defined by the import. + crate fn import( + &self, + binding: &'a NameBinding<'a>, + import: &'a Import<'a>, + ) -> &'a NameBinding<'a> { + let vis = if binding.pseudo_vis().is_at_least(import.vis.get(), self) || + // cf. `PUB_USE_OF_PRIVATE_EXTERN_CRATE` + !import.is_glob() && binding.is_extern_crate() + { + import.vis.get() + } else { + binding.pseudo_vis() + }; + + if let ImportKind::Glob { ref max_vis, .. } = import.kind { + if vis == import.vis.get() || vis.is_at_least(max_vis.get(), self) { + max_vis.set(vis) + } + } + + self.arenas.alloc_name_binding(NameBinding { + kind: NameBindingKind::Import { binding, import, used: Cell::new(false) }, + ambiguity: None, + span: import.span, + vis, + expansion: import.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<T, F>(&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 import in module.glob_importers.borrow_mut().iter() { + let mut ident = key.ident; + let scope = match ident.span.reverse_glob_adjust(module.expansion, import.span) { + Some(Some(def)) => self.macro_def_scope(def), + Some(None) => import.parent_scope.module, + None => continue, + }; + if self.is_accessible_from(binding.vis, scope) { + let imported_binding = self.import(binding, import); + let key = BindingKey { ident, ..key }; + let _ = self.try_define(import.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, import: &'a Import<'a>) { + if let ImportKind::Single { target, .. } = import.kind { + let dummy_binding = self.dummy_binding; + let dummy_binding = self.import(dummy_binding, import); + self.per_ns(|this, ns| { + let key = this.new_key(target, ns); + let _ = this.try_define(import.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<String>, + note: Vec<String>, + suggestion: Option<Suggestion>, +} + +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<DefId> { + 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 ImportKind::Single { source, ref source_bindings, .. } = import.kind { + 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::<Vec<_>>(), + &import.kind, + 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::<Vec<_>>(), + &import.kind, + 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, None); + } + } + + fn throw_unresolved_import_error( + &self, + errors: Vec<(String, UnresolvedImportError)>, + span: Option<MultiSpan>, + ) { + /// 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::<Vec<_>>(); + + 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, import: &'b Import<'b>) -> bool { + debug!( + "(resolving import for module) resolving import `{}::...` in `{}`", + Segment::names_to_string(&import.module_path), + module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()), + ); + + let module = if let Some(module) = import.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 = import.vis.replace(ty::Visibility::Invisible); + let path_res = self.r.resolve_path( + &import.module_path, + None, + &import.parent_scope, + false, + import.span, + import.crate_lint(), + ); + import.vis.set(orig_vis); + + match path_res { + PathResult::Module(module) => module, + PathResult::Indeterminate => return false, + PathResult::NonModule(..) | PathResult::Failed { .. } => return true, + } + }; + + import.imported_module.set(Some(module)); + let (source, target, source_bindings, target_bindings, type_ns_only) = match import.kind { + ImportKind::Single { + source, + target, + ref source_bindings, + ref target_bindings, + type_ns_only, + .. + } => (source, target, source_bindings, target_bindings, type_ns_only), + ImportKind::Glob { .. } => { + self.resolve_glob_import(import); + 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 = import.vis.replace(ty::Visibility::Invisible); + let binding = this.resolve_ident_in_module( + module, + source, + ns, + &import.parent_scope, + false, + import.span, + ); + import.vis.set(orig_vis); + + source_bindings[ns].set(binding); + } else { + return; + }; + + let parent = import.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(import)); + }); + } + Ok(binding) if !binding.is_importable() => { + let msg = format!("`{}` is not directly importable", target); + struct_span_err!(this.session, import.span, E0253, "{}", &msg) + .span_label(import.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(import); + } + Ok(binding) => { + let imported_binding = this.import(binding, import); + 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, import: &'b Import<'b>) -> Option<UnresolvedImportError> { + let orig_vis = import.vis.replace(ty::Visibility::Invisible); + let orig_unusable_binding = match &import.kind { + ImportKind::Single { target_bindings, .. } => { + Some(mem::replace(&mut self.r.unusable_binding, target_bindings[TypeNS].get())) + } + _ => None, + }; + let prev_ambiguity_errors_len = self.r.ambiguity_errors.len(); + let path_res = self.r.resolve_path( + &import.module_path, + None, + &import.parent_scope, + true, + import.span, + import.crate_lint(), + ); + let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len; + if let Some(orig_unusable_binding) = orig_unusable_binding { + self.r.unusable_binding = orig_unusable_binding; + } + import.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((import.id, TypeNS)); + } + let module = match path_res { + PathResult::Module(module) => { + // Consistency checks, analogous to `finalize_macro_resolutions`. + if let Some(initial_module) = import.imported_module.get() { + if !ModuleOrUniformRoot::same_def(module, initial_module) && no_ambiguity { + span_bug!(import.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(import.span, msg).note(msg_note).emit(); + } + } + + module + } + PathResult::Failed { is_error_from_last_segment: false, span, label, suggestion } => { + if no_ambiguity { + assert!(import.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!(import.imported_module.get().is_none()); + let err = match self.make_path_suggestion( + span, + import.module_path.clone(), + &import.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!(import.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 import.kind { + ImportKind::Single { + source, + target, + ref source_bindings, + ref target_bindings, + type_ns_only, + .. + } => (source, target, source_bindings, target_bindings, type_ns_only), + ImportKind::Glob { is_prelude, ref max_vis } => { + if import.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 = import.module_path.clone(); + full_path.push(Segment::from_ident(Ident::invalid())); + self.r.lint_if_path_starts_with_module( + import.crate_lint(), + &full_path, + import.span, + None, + ); + } + + if let ModuleOrUniformRoot::Module(module) = module { + if module.def_id() == import.parent_scope.module.def_id() { + // Importing a module into itself is not allowed. + return Some(UnresolvedImportError { + span: import.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(import.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, import.id, import.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 = import.vis.replace(ty::Visibility::Invisible); + let orig_unusable_binding = + mem::replace(&mut this.unusable_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, + &import.parent_scope, + true, + import.span, + ); + this.last_import_segment = orig_last_import_segment; + this.unusable_binding = orig_unusable_binding; + import.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() { + if target.name == kw::Underscore + && initial_binding.is_extern_crate() + && !initial_binding.is_import() + { + this.record_use( + ident, + ns, + target_binding, + import.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!(import.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(import.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. + // Re-enable 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, + &import.parent_scope, + true, + import.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, _) => 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.name, 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(import, 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: import.span, + label: Some(label), + note, + suggestion, + }) + } else { + // `resolve_ident_in_module` reported a privacy error. + self.r.import_dummy_binding(import); + 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 = import.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, + import.id, + import.span, + &msg, + ); + } else if ns == TypeNS { + struct_span_err!( + self.r.session, + import.span, + E0365, + "`{}` is private, and cannot be re-exported", + ident + ) + .span_label(import.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, import.span, E0364, "{}", &msg) + .span_note(import.span, ¬e_msg) + .emit(); + } + } + + if import.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 = import.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( + import.crate_lint(), + &full_path, + import.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 Ok(binding) = source_bindings[ns].get() { + this.import_res_map.entry(import.id).or_default()[ns] = Some(binding.res()); + } + }); + + self.check_for_redundant_imports(ident, import, source_bindings, target_bindings, target); + + debug!("(resolving single import) successfully resolved import"); + None + } + + fn check_for_redundant_imports( + &mut self, + ident: Ident, + import: &'b Import<'b>, + source_bindings: &PerNS<Cell<Result<&'b NameBinding<'b>, Determinacy>>>, + target_bindings: &PerNS<Cell<Option<&'b NameBinding<'b>>>>, + target: Ident, + ) { + // Skip if the import was produced by a macro. + if import.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(..) = import.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 Ok(binding) = source_bindings[ns].get() { + if binding.res() == Res::Err { + return; + } + + let orig_unusable_binding = + mem::replace(&mut this.unusable_binding, target_bindings[ns].get()); + + match this.early_resolve_ident_in_lexical_scope( + target, + ScopeSet::All(ns, false), + &import.parent_scope, + false, + false, + import.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.unusable_binding = orig_unusable_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, + import.id, + import.span, + &format!("the item `{}` is imported redundantly", ident), + BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident), + ); + } + } + + fn resolve_glob_import(&mut self, import: &'b Import<'b>) { + let module = match import.imported_module.get().unwrap() { + ModuleOrUniformRoot::Module(module) => module, + _ => { + self.r.session.span_err(import.span, "cannot glob-import all possible crates"); + return; + } + }; + + if module.is_trait() { + self.r.session.span_err(import.span, "items in traits are not importable."); + return; + } else if module.def_id() == import.parent_scope.module.def_id() { + return; + } else if let ImportKind::Glob { is_prelude: true, .. } = import.kind { + self.r.prelude = Some(module); + return; + } + + // Add to module's glob_importers + module.glob_importers.borrow_mut().push(import); + + // 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::<Vec<_>>(); + for (mut key, binding) in bindings { + let scope = match key.ident.span.reverse_glob_adjust(module.expansion, import.span) { + Some(Some(def)) => self.r.macro_def_scope(def), + Some(None) => import.parent_scope.module, + None => continue, + }; + if self.r.is_accessible_from(binding.pseudo_vis(), scope) { + let imported_binding = self.r.import(binding, import); + let _ = self.r.try_define(import.parent_scope.module, key, imported_binding); + } + } + + // Record the destination of this import + self.r.record_partial_res(import.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().map_id(|id| this.local_def_id(id)); + if res != def::Res::Err { + reexports.push(Export { ident, res, span: binding.span, vis: binding.vis }); + } + } + + if let NameBindingKind::Import { binding: orig_binding, import, .. } = binding.kind { + if ns == TypeNS + && orig_binding.is_variant() + && !orig_binding.vis.is_at_least(binding.vis, &*this) + { + let msg = match import.kind { + ImportKind::Single { .. } => { + format!("variant `{}` is private and cannot be re-exported", ident) + } + ImportKind::Glob { .. } => { + 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 kind {:?}", s), + }; + let mut err = this.session.struct_span_err(binding.span, &msg); + + let imported_module = match import.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 = import.module_path.len() - 1; + let enum_ident = import.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().guess_head_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.is_empty() { + if let Some(def_id) = module.def_id() { + // Call to `expect_local` should be fine because current + // code is only called for local modules. + self.r.export_map.insert(def_id.expect_local(), reexports); + } + } + } +} + +fn import_path_to_string(names: &[Ident], import_kind: &ImportKind<'_>, 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::<Vec<_>>()) + } else { + let names = if global { &names[1..] } else { names }; + if names.is_empty() { + import_kind_to_string(import_kind) + } else { + format!( + "{}::{}", + names_to_string(&names.iter().map(|ident| ident.name).collect::<Vec<_>>()), + import_kind_to_string(import_kind), + ) + } + } +} + +fn import_kind_to_string(import_kind: &ImportKind<'_>) -> String { + match import_kind { + ImportKind::Single { source, .. } => source.to_string(), + ImportKind::Glob { .. } => "*".to_string(), + ImportKind::ExternCrate { .. } => "<extern crate>".to_string(), + ImportKind::MacroUse => "#[macro_use]".to_string(), + } +} |