blob: 4595a96ce24f53d166a735c869950f2ed0234d10 [file] [log] [blame]
//! 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::ast::NodeId;
use rustc_ast::unwrap_or;
use rustc_ast::util::lev_distance::find_best_match_for_name;
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 log::*;
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() {
// Note that as_str() de-gensyms the Symbol
if target.name.as_str() == "_"
&& initial_binding.is_extern_crate()
&& !initial_binding.is_import()
{
this.record_use(
ident,
ns,
target_binding,
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.as_str(), None).map(|suggestion| {
(
vec![(ident.span, suggestion.to_string())],
String::from("a similar name exists in the module"),
Applicability::MaybeIncorrect,
)
});
let (suggestion, note) =
match self.check_for_module_export_macro(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, &note_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(),
}
}