rust/compiler/rustc_resolve/src/imports.rs

1273 lines
52 KiB
Rust

//! A bunch of methods and structures more or less related to resolving imports.
use crate::diagnostics::{import_candidates, DiagnosticMode, Suggestion};
use crate::Determinacy::{self, *};
use crate::Namespace::*;
use crate::{module_to_string, names_to_string, ImportSuggestion};
use crate::{
AmbiguityError, AmbiguityErrorMisc, 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::edit_distance::find_best_match_for_name;
use rustc_span::hygiene::LocalExpnId;
use rustc_span::symbol::{kw, Ident, Symbol};
use rustc_span::Span;
use std::cell::Cell;
use std::{mem, ptr};
type Res = def::Res<NodeId>;
/// Contains data for specific kinds of imports.
#[derive(Clone)]
pub(crate) 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,
/// The ID of the `UseTree` 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.
id: NodeId,
},
Glob {
is_prelude: bool,
// The visibility of the greatest re-export.
// n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
max_vis: Cell<Option<ty::Visibility>>,
id: NodeId,
},
ExternCrate {
source: Option<Symbol>,
target: Ident,
id: NodeId,
},
MacroUse,
MacroExport,
}
/// Manually implement `Debug` for `ImportKind` because the `source/target_bindings`
/// contain `Cell`s which can introduce infinite loops while printing.
impl<'a> std::fmt::Debug for ImportKind<'a> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
use ImportKind::*;
match self {
Single {
ref source,
ref target,
ref source_bindings,
ref target_bindings,
ref type_ns_only,
ref nested,
ref id,
} => f
.debug_struct("Single")
.field("source", source)
.field("target", target)
// Ignore the nested bindings to avoid an infinite loop while printing.
.field(
"source_bindings",
&source_bindings.clone().map(|b| b.into_inner().map(|_| format_args!(".."))),
)
.field(
"target_bindings",
&target_bindings.clone().map(|b| b.into_inner().map(|_| format_args!(".."))),
)
.field("type_ns_only", type_ns_only)
.field("nested", nested)
.field("id", id)
.finish(),
Glob { ref is_prelude, ref max_vis, ref id } => f
.debug_struct("Glob")
.field("is_prelude", is_prelude)
.field("max_vis", max_vis)
.field("id", id)
.finish(),
ExternCrate { ref source, ref target, ref id } => f
.debug_struct("ExternCrate")
.field("source", source)
.field("target", target)
.field("id", id)
.finish(),
MacroUse => f.debug_struct("MacroUse").finish(),
MacroExport => f.debug_struct("MacroExport").finish(),
}
}
}
/// One import.
#[derive(Debug, Clone)]
pub(crate) struct Import<'a> {
pub kind: ImportKind<'a>,
/// Node ID of the "root" use item -- this is always the same as `ImportKind`'s `id`
/// (if it exists) 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
/// ```ignore (incomplete code)
/// use foo::bar::{a, b}
/// ```
/// this would be the ID of the `use foo::bar` `UseTree` node.
/// In case of imports without their own node ID it's the closest node that can be used,
/// for example, for reporting lints.
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<Option<ty::Visibility>>,
pub used: Cell<bool>,
}
impl<'a> Import<'a> {
pub(crate) fn is_glob(&self) -> bool {
matches!(self.kind, ImportKind::Glob { .. })
}
pub(crate) fn is_nested(&self) -> bool {
match self.kind {
ImportKind::Single { nested, .. } => nested,
_ => false,
}
}
pub(crate) fn expect_vis(&self) -> ty::Visibility {
self.vis.get().expect("encountered cleared import visibility")
}
pub(crate) fn id(&self) -> Option<NodeId> {
match self.kind {
ImportKind::Single { id, .. }
| ImportKind::Glob { id, .. }
| ImportKind::ExternCrate { id, .. } => Some(id),
ImportKind::MacroUse | ImportKind::MacroExport => None,
}
}
}
/// 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));
}
}
/// 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>,
candidates: Option<Vec<ImportSuggestion>>,
}
// 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.expect_vis().is_public(),
_ => false,
}
}
impl<'a, 'tcx> Resolver<'a, 'tcx> {
/// 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 import_vis = import.expect_vis().to_def_id();
let vis = if binding.vis.is_at_least(import_vis, self.tcx)
|| pub_use_of_private_extern_crate_hack(import, binding)
{
import_vis
} else {
binding.vis
};
if let ImportKind::Glob { ref max_vis, .. } = import.kind {
if vis == import_vis
|| max_vis.get().map_or(true, |max_vis| vis.is_at_least(max_vis, self.tcx))
{
max_vis.set(Some(vis.expect_local()))
}
}
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 && old_binding.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.tcx) {
// 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, 'tcx>, &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);
if let Some(id) = import.id() {
self.used_imports.insert(id);
}
}
}
// 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(crate) fn resolve_imports(&mut self) {
let mut prev_indeterminate_count = usize::MAX;
let mut indeterminate_count = self.indeterminate_imports.len() * 3;
while indeterminate_count < prev_indeterminate_count {
prev_indeterminate_count = indeterminate_count;
indeterminate_count = 0;
for import in mem::take(&mut self.indeterminate_imports) {
let import_indeterminate_count = self.resolve_import(&import);
indeterminate_count += import_indeterminate_count;
match import_indeterminate_count {
0 => self.determined_imports.push(import),
_ => self.indeterminate_imports.push(import),
}
}
}
}
pub(crate) fn finalize_imports(&mut self) {
for module in self.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.determined_imports);
let indeterminate_imports = mem::take(&mut self.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.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);
errors = vec![];
}
if seen_spans.insert(err.span) {
errors.push((import, 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,
candidates: None,
};
// FIXME: there should be a better way of doing this than
// formatting this as a string then checking for `::`
if path.contains("::") {
errors.push((import, err))
}
}
}
if !errors.is_empty() {
self.throw_unresolved_import_error(errors);
}
}
fn throw_unresolved_import_error(&self, errors: Vec<(&Import<'_>, UnresolvedImportError)>) {
if errors.is_empty() {
return;
}
/// Upper limit on the number of `span_label` messages.
const MAX_LABEL_COUNT: usize = 10;
let span = MultiSpan::from_spans(errors.iter().map(|(_, err)| err.span).collect());
let paths = errors
.iter()
.map(|(import, err)| {
let path = import_path_to_string(
&import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
&import.kind,
err.span,
);
format!("`{path}`")
})
.collect::<Vec<_>>();
let msg = format!("unresolved import{} {}", pluralize!(paths.len()), paths.join(", "),);
let mut diag = struct_span_err!(self.tcx.sess, span, E0432, "{}", &msg);
if let Some((_, UnresolvedImportError { note: Some(note), .. })) = errors.iter().last() {
diag.note(note);
}
for (import, 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);
}
if let Some(candidates) = &err.candidates {
match &import.kind {
ImportKind::Single { nested: false, source, target, .. } => import_candidates(
self.tcx,
&mut diag,
Some(err.span),
&candidates,
DiagnosticMode::Import,
(source != target)
.then(|| format!(" as {target}"))
.as_deref()
.unwrap_or(""),
),
ImportKind::Single { nested: true, source, target, .. } => {
import_candidates(
self.tcx,
&mut diag,
None,
&candidates,
DiagnosticMode::Normal,
(source != target)
.then(|| format!(" as {target}"))
.as_deref()
.unwrap_or(""),
);
}
_ => {}
}
}
}
diag.emit();
}
/// Attempts to resolve the given import, returning:
/// - `0` means its resolution is determined.
/// - Other values mean that indeterminate exists under certain namespaces.
///
/// Meanwhile, if resolve successful, the resolved bindings are written
/// into the module.
fn resolve_import(&mut self, import: &'a Import<'a>) -> usize {
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.take();
let path_res = self.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 3,
PathResult::NonModule(..) | PathResult::Failed { .. } => return 0,
}
};
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 0;
}
_ => unreachable!(),
};
let mut indeterminate_count = 0;
self.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.take();
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_count += 1,
// 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.tcx.sess, 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_count
}
/// 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: &'a Import<'a>) -> Option<UnresolvedImportError> {
let orig_vis = import.vis.take();
let ignore_binding = match &import.kind {
ImportKind::Single { target_bindings, .. } => target_bindings[TypeNS].get(),
_ => None,
};
let prev_ambiguity_errors_len = self.ambiguity_errors.len();
let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span);
let path_res = self.resolve_path(
&import.module_path,
None,
&import.parent_scope,
Some(finalize),
ignore_binding,
);
let no_ambiguity = self.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.privacy_errors.is_empty() {
let msg = "cannot determine resolution for the import";
let msg_note = "import resolution is stuck, try simplifying other imports";
self.tcx.sess.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.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,
)),
candidates: None,
},
None => UnresolvedImportError {
span,
label: Some(label),
note: None,
suggestion,
candidates: None,
},
};
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, import_id) =
match import.kind {
ImportKind::Single {
source,
target,
ref source_bindings,
ref target_bindings,
type_ns_only,
id,
..
} => (source, target, source_bindings, target_bindings, type_ns_only, id),
ImportKind::Glob { is_prelude, ref max_vis, id } => {
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.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,
candidates: None,
});
}
}
if !is_prelude
&& let Some(max_vis) = max_vis.get()
&& !max_vis.is_at_least(import.expect_vis(), self.tcx)
{
let msg = "glob import doesn't reexport anything because no candidate is public enough";
self.lint_buffer.buffer_lint(UNUSED_IMPORTS, id, import.span, msg);
}
return None;
}
_ => unreachable!(),
};
let mut all_ns_err = true;
self.per_ns(|this, ns| {
if !type_ns_only || ns == TypeNS {
let orig_vis = import.vis.take();
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_binding = 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
});
let res = binding.res();
if let Ok(initial_binding) = initial_binding {
let initial_res = initial_binding.res();
if res != initial_res && this.ambiguity_errors.is_empty() {
this.ambiguity_errors.push(AmbiguityError {
kind: AmbiguityKind::Import,
ident,
b1: initial_binding,
b2: binding,
misc1: AmbiguityErrorMisc::None,
misc2: AmbiguityErrorMisc::None,
});
}
} 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.tcx.sess.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.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.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.name == ident.name {
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)
}
}
};
let parent_suggestion =
self.lookup_import_candidates(ident, TypeNS, &import.parent_scope, |_| true);
Some(UnresolvedImportError {
span: import.span,
label: Some(label),
note,
suggestion,
candidates: if !parent_suggestion.is_empty() {
Some(parent_suggestion)
} else {
None
},
})
} 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.per_ns(|this, ns| {
if let Ok(binding) = source_bindings[ns].get() {
if !binding.vis.is_at_least(import.expect_vis(), this.tcx) {
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.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.tcx.sess, 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.tcx.sess, import.span, E0364, "{error_msg}");
match binding.kind {
NameBindingKind::Res(Res::Def(DefKind::Macro(_), def_id))
// exclude decl_macro
if self.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.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.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: &'a Import<'a>,
source_bindings: &PerNS<Cell<Result<&'a NameBinding<'a>, Determinacy>>>,
target_bindings: &PerNS<Cell<Option<&'a NameBinding<'a>>>>,
target: Ident,
) {
// This function is only called for single imports.
let ImportKind::Single { id, .. } = import.kind else { unreachable!() };
// 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.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.lint_buffer.buffer_lint_with_diagnostic(
UNUSED_IMPORTS,
id,
import.span,
&format!("the item `{}` is imported redundantly", ident),
BuiltinLintDiagnostics::RedundantImport(redundant_spans, ident),
);
}
}
fn resolve_glob_import(&mut self, import: &'a Import<'a>) {
// This function is only called for glob imports.
let ImportKind::Glob { id, is_prelude, .. } = import.kind else { unreachable!() };
let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
self.tcx.sess.span_err(import.span, "cannot glob-import all possible crates");
return;
};
if module.is_trait() {
self.tcx.sess.span_err(import.span, "items in traits are not importable");
return;
} else if ptr::eq(module, import.parent_scope.module) {
return;
} else if is_prelude {
self.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
.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.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 _ = self.try_define(import.parent_scope.module, key, imported_binding);
}
}
// Record the destination of this import
self.record_partial_res(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<'a>) {
// 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, |this, ident, _, binding| {
if let Some(res) = this.is_reexport(binding) {
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.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(),
ImportKind::MacroExport => "#[macro_export]".to_string(),
}
}