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Diffstat (limited to 'compiler/rustc_resolve/src/imports.rs')
| -rw-r--r-- | compiler/rustc_resolve/src/imports.rs | 1151 |
1 files changed, 1151 insertions, 0 deletions
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs new file mode 100644 index 000000000..b89273990 --- /dev/null +++ b/compiler/rustc_resolve/src/imports.rs @@ -0,0 +1,1151 @@ +//! A bunch of methods and structures more or less related to resolving imports. + +use crate::diagnostics::Suggestion; +use crate::Determinacy::{self, *}; +use crate::Namespace::{MacroNS, TypeNS}; +use crate::{module_to_string, names_to_string}; +use crate::{AmbiguityKind, BindingKey, ModuleKind, ResolutionError, Resolver, Segment}; +use crate::{Finalize, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet}; +use crate::{NameBinding, NameBindingKind, PathResult}; + +use rustc_ast::NodeId; +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::intern::Interned; +use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan}; +use rustc_hir::def::{self, DefKind, PartialRes}; +use rustc_middle::metadata::ModChild; +use rustc_middle::span_bug; +use rustc_middle::ty; +use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS}; +use rustc_session::lint::BuiltinLintDiagnostics; +use rustc_span::hygiene::LocalExpnId; +use rustc_span::lev_distance::find_best_match_for_name; +use rustc_span::symbol::{kw, Ident, Symbol}; +use rustc_span::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, + /// Additional `NodeId`s allocated to a `ast::UseTree` for automatically generated `use` statement + /// (eg. implicit struct constructors) + additional_ids: (NodeId, NodeId), + }, + 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)] +pub(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 merciless 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 { + matches!(self.kind, ImportKind::Glob { .. }) + } + + pub fn is_nested(&self) -> bool { + match self.kind { + ImportKind::Single { nested, .. } => nested, + _ => false, + } + } +} + +/// Records information about the resolution of a name in a namespace of a module. +#[derive(Clone, Default, Debug)] +pub(crate) 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. + pub single_imports: FxHashSet<Interned<'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>>, + pub 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 + } + }) + } + + pub(crate) fn add_single_import(&mut self, import: &'a Import<'a>) { + self.single_imports.insert(Interned::new_unchecked(import)); + } +} + +// Reexports of the form `pub use foo as bar;` where `foo` is `extern crate foo;` +// are permitted for backward-compatibility under a deprecation lint. +fn pub_use_of_private_extern_crate_hack(import: &Import<'_>, binding: &NameBinding<'_>) -> bool { + match (&import.kind, &binding.kind) { + ( + ImportKind::Single { .. }, + NameBindingKind::Import { + import: Import { kind: ImportKind::ExternCrate { .. }, .. }, + .. + }, + ) => import.vis.get().is_public(), + _ => false, + } +} + +impl<'a> Resolver<'a> { + // Given a binding and an import that resolves to it, + // return the corresponding binding defined by the import. + pub(crate) fn import( + &self, + binding: &'a NameBinding<'a>, + import: &'a Import<'a>, + ) -> &'a NameBinding<'a> { + let vis = if binding.vis.is_at_least(import.vis.get(), self) + || pub_use_of_private_extern_crate_hack(import, binding) + { + import.vis.get() + } else { + binding.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. + pub(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 != LocalExpnId::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.expn_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, + // also mark such failed imports as used to avoid duplicate diagnostics. + fn import_dummy_binding(&mut self, import: &'a Import<'a>) { + if let ImportKind::Single { target, ref target_bindings, .. } = import.kind { + if target_bindings.iter().any(|binding| binding.get().is_some()) { + return; // Has resolution, do not create the dummy binding + } + 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); + }); + self.record_use(target, dummy_binding, false); + } else if import.imported_module.get().is_none() { + import.used.set(true); + self.used_imports.insert(import.id); + } + } +} + +/// 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: Option<String>, + suggestion: Option<Suggestion>, +} + +pub struct ImportResolver<'a, 'b> { + pub r: &'a mut Resolver<'b>, +} + +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))) + { + let unresolved_import_error = self.finalize_import(import); + + // If this import is unresolved then create a dummy import + // resolution for it so that later resolve stages won't complain. + self.r.import_dummy_binding(import); + + if let Some(err) = unresolved_import_error { + 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 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 { + 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: None, + suggestion: None, + }; + if path.contains("::") { + 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: Some(note), .. })) = errors.iter().last() { + diag.note(note); + } + + 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 { + if suggestions.is_empty() { + diag.help(&msg); + continue; + } + 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.maybe_resolve_path(&import.module_path, None, &import.parent_scope); + 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, + None, + None, + ); + 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 => {} + Ok(binding) if binding.is_importable() => { + let imported_binding = this.import(binding, import); + target_bindings[ns].set(Some(imported_binding)); + this.define(parent, target, ns, imported_binding); + } + source_binding @ (Ok(..) | Err(Determined)) => { + if source_binding.is_ok() { + 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(); + } + let key = this.new_key(target, ns); + this.update_resolution(parent, key, |_, resolution| { + resolution.single_imports.remove(&Interned::new_unchecked(import)); + }); + } + } + } + }); + + !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 ignore_binding = match &import.kind { + ImportKind::Single { target_bindings, .. } => target_bindings[TypeNS].get(), + _ => None, + }; + let prev_ambiguity_errors_len = self.r.ambiguity_errors.len(); + let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span); + let path_res = self.r.resolve_path( + &import.module_path, + None, + &import.parent_scope, + Some(finalize), + ignore_binding, + ); + let no_ambiguity = self.r.ambiguity_errors.len() == prev_ambiguity_errors_len; + import.vis.set(orig_vis); + 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: None, + suggestion, + }, + }; + return Some(err); + } + return None; + } + PathResult::NonModule(_) => { + if no_ambiguity { + assert!(import.imported_module.get().is_none()); + } + // The error was already reported earlier. + return None; + } + PathResult::Indeterminate => 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::empty())); + self.r.lint_if_path_starts_with_module(Some(finalize), &full_path, None); + } + + if let ModuleOrUniformRoot::Module(module) = module { + if ptr::eq(module, import.parent_scope.module) { + // 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: None, + suggestion: None, + }); + } + } + if !is_prelude && + max_vis.get() != ty::Visibility::Invisible && // Allow empty globs. + !max_vis.get().is_at_least(import.vis.get(), &*self.r) + { + 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 binding = this.resolve_ident_in_module( + module, + ident, + ns, + &import.parent_scope, + Some(Finalize { report_private: false, ..finalize }), + target_bindings[ns].get(), + ); + 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, + 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, + Some(finalize), + None, + ); + 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), + } + }) + .collect::<Vec<Symbol>>(); + + 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, None), + }; + + 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. + None + }; + } + + let mut reexport_error = None; + let mut any_successful_reexport = false; + let mut crate_private_reexport = false; + self.r.per_ns(|this, ns| { + if let Ok(binding) = source_bindings[ns].get() { + let vis = import.vis.get(); + if !binding.vis.is_at_least(vis, &*this) { + reexport_error = Some((ns, binding)); + if let ty::Visibility::Restricted(binding_def_id) = binding.vis { + if binding_def_id.is_top_level_module() { + crate_private_reexport = true; + } + } + } 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 pub_use_of_private_extern_crate_hack(import, binding) { + 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 { + let error_msg = if crate_private_reexport { + format!( + "`{}` is only public within the crate, and cannot be re-exported outside", + ident + ) + } else { + format!("`{}` is private, and cannot be re-exported", ident) + }; + + if ns == TypeNS { + let label_msg = if crate_private_reexport { + format!("re-export of crate public `{}`", ident) + } else { + format!("re-export of private `{}`", ident) + }; + + struct_span_err!(self.r.session, import.span, E0365, "{}", error_msg) + .span_label(import.span, label_msg) + .note(&format!("consider declaring type or module `{}` with `pub`", ident)) + .emit(); + } else { + let mut err = + struct_span_err!(self.r.session, import.span, E0364, "{error_msg}"); + match binding.kind { + NameBindingKind::Res(Res::Def(DefKind::Macro(_), def_id), _) + // exclude decl_macro + if self.r.get_macro_by_def_id(def_id).macro_rules => + { + err.span_help( + binding.span, + "consider adding a `#[macro_export]` to the macro in the imported module", + ); + } + _ => { + err.span_note( + import.span, + &format!( + "consider marking `{ident}` as `pub` in the imported module" + ), + ); + } + } + err.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(Some(finalize), &full_path, 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 != LocalExpnId::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; + } + + match this.early_resolve_ident_in_lexical_scope( + target, + ScopeSet::All(ns, false), + &import.parent_scope, + None, + false, + target_bindings[ns].get(), + ) { + 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), + } + } + }); + + 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 ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else { + 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 ptr::eq(module, import.parent_scope.module) { + 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.expn_def_scope(def), + Some(None) => import.parent_scope.module, + None => continue, + }; + if self.r.is_accessible_from(binding.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(); + + if let Some(def_id) = module.opt_def_id() { + let mut reexports = Vec::new(); + + module.for_each_child(self.r, |_, ident, _, binding| { + // FIXME: Consider changing the binding inserted by `#[macro_export] macro_rules` + // into the crate root to actual `NameBindingKind::Import`. + if binding.is_import() + || matches!(binding.kind, NameBindingKind::Res(_, _is_macro_export @ true)) + { + let res = binding.res().expect_non_local(); + // Ambiguous imports are treated as errors at this point and are + // not exposed to other crates (see #36837 for more details). + if res != def::Res::Err && !binding.is_ambiguity() { + reexports.push(ModChild { + ident, + res, + vis: binding.vis, + span: binding.span, + macro_rules: false, + }); + } + } + }); + + if !reexports.is_empty() { + // Call to `expect_local` should be fine because current + // code is only called for local modules. + self.r.reexport_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(), + } +} |