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rust/rust/a123594de1feec1732ed9251135bc42ccaaef8f3/./compiler/rustc_resolve/src/imports.rs
blob: 499f9ea297362d8c3245265b5945a44218bbde3a [file]
//! A bunch of methods and structures more or less related to resolving imports.
use std::cmp::Ordering;
use std::mem;
use rustc_ast::NodeId;
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
use rustc_data_structures::intern::Interned;
use rustc_errors::{Applicability, BufferedEarlyLint, Diagnostic};
use rustc_expand::base::SyntaxExtensionKind;
use rustc_hir::def::{self, DefKind, PartialRes};
use rustc_hir::def_id::{DefId, LocalDefId, LocalDefIdMap};
use rustc_middle::metadata::{AmbigModChild, ModChild, Reexport};
use rustc_middle::span_bug;
use rustc_middle::ty::Visibility;
use rustc_session::diagnostics::feature_err;
use rustc_session::lint::LintId;
use rustc_session::lint::builtin::{
AMBIGUOUS_GLOB_REEXPORTS, EXPORTED_PRIVATE_DEPENDENCIES, HIDDEN_GLOB_REEXPORTS,
PUB_USE_OF_PRIVATE_EXTERN_CRATE, REDUNDANT_IMPORTS, UNUSED_IMPORTS,
};
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::hygiene::LocalExpnId;
use rustc_span::{Ident, Span, Symbol, kw, sym};
use tracing::debug;
use crate::Namespace::{self, *};
use crate::diagnostics::impls::{OnUnknownData, Suggestion};
use crate::diagnostics::{
self, CannotBeReexportedCratePublic, CannotBeReexportedCratePublicNS,
CannotBeReexportedPrivate, CannotBeReexportedPrivateNS, CannotDetermineImportResolution,
CannotGlobImportAllCrates, ConsiderAddingMacroExport, ConsiderMarkingAsPub,
ConsiderMarkingAsPubCrate,
};
use crate::ref_mut::{CmCell, CmRefCell};
use crate::{
AmbiguityError, BindingKey, Decl, DeclData, DeclKind, Determinacy, Finalize, IdentKey,
ImportSuggestion, ImportSummary, LocalModule, ModuleOrUniformRoot, ParentScope, PathResult,
PerNS, Res, ResolutionError, Resolver, ScopeSet, Segment, Used, module_to_string,
names_to_string,
};
/// A potential import declaration in the process of being planted into a module.
/// Also used for lazily planting names from `--extern` flags to extern prelude.
#[derive(Clone, Copy, Default, PartialEq, Debug)]
pub(crate) enum PendingDecl<'ra> {
Ready(Option<Decl<'ra>>),
#[default]
Pending,
}
enum ImportResolutionKind<'ra> {
// these are the decls the import imports, not the import declarations themselves
Single(PerNS<PendingDecl<'ra>>),
Glob(Vec<(Decl<'ra>, BindingKey, Span /* orig_ident_span */)>),
}
pub(crate) struct ImportResolution<'ra> {
kind: ImportResolutionKind<'ra>,
imported_module: ModuleOrUniformRoot<'ra>,
}
impl<'ra> PendingDecl<'ra> {
pub(crate) fn decl(self) -> Option<Decl<'ra>> {
match self {
PendingDecl::Ready(decl) => decl,
PendingDecl::Pending => None,
}
}
}
/// Contains data for specific kinds of imports.
pub(crate) enum ImportKind<'ra> {
Single {
/// `source` in `use prefix::source as target`.
source: Ident,
/// `target` in `use prefix::source as target`.
/// It will directly use `source` when the format is `use prefix::source`.
target: Ident,
/// Name declarations introduced by the import.
decls: PerNS<CmCell<PendingDecl<'ra>>>,
/// Did this import result from a nested import? i.e. `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,
def_id: LocalDefId,
},
Glob {
// 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: CmCell<Option<Visibility>>,
id: NodeId,
def_id: LocalDefId,
},
ExternCrate {
source: Option<Symbol>,
target: Ident,
id: NodeId,
def_id: LocalDefId,
},
MacroUse {
/// A field has been added indicating whether it should be reported as a lint,
/// addressing issue#119301.
warn_private: bool,
},
MacroExport,
}
/// Manually implement `Debug` for `ImportKind` because the `source/target_bindings`
/// contain `Cell`s which can introduce infinite loops while printing.
impl<'ra> std::fmt::Debug for ImportKind<'ra> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
use ImportKind::*;
match self {
Single { source, target, decls, nested, id, def_id } => f
.debug_struct("Single")
.field("source", source)
.field("target", target)
// Ignore the nested bindings to avoid an infinite loop while printing.
.field(
"decls",
&decls.clone().map(|b| b.into_inner().decl().map(|_| format_args!(".."))),
)
.field("nested", nested)
.field("id", id)
.field("def_id", def_id)
.finish(),
Glob { max_vis, id, def_id } => f
.debug_struct("Glob")
.field("max_vis", max_vis)
.field("id", id)
.field("def_id", def_id)
.finish(),
ExternCrate { source, target, id, def_id } => f
.debug_struct("ExternCrate")
.field("source", source)
.field("target", target)
.field("id", id)
.field("def_id", def_id)
.finish(),
MacroUse { warn_private } => {
f.debug_struct("MacroUse").field("warn_private", warn_private).finish()
}
MacroExport => f.debug_struct("MacroExport").finish(),
}
}
}
/// One import.
#[derive(Debug)]
pub(crate) struct ImportData<'ra> {
pub kind: ImportKind<'ra>,
/// 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<'ra>,
pub module_path: Vec<Segment>,
/// The resolution of `module_path`:
///
/// | `module_path` | `imported_module` | remark |
/// |-|-|-|
/// |`use prefix::foo`| `ModuleOrUniformRoot::Module(prefix)` | - |
/// |`use ::foo` | `ModuleOrUniformRoot::ExternPrelude` | 2018+ editions |
/// |`use ::foo` | `ModuleOrUniformRoot::ModuleAndExternPrelude` | a special case in 2015 edition |
/// |`use foo` | `ModuleOrUniformRoot::CurrentScope` | - |
pub imported_module: CmCell<Option<ModuleOrUniformRoot<'ra>>>,
pub vis: Visibility,
/// Span of the visibility.
pub vis_span: Span,
/// A `#[diagnostic::on_unknown]` attribute applied
/// to the given import. This allows crates to specify
/// custom error messages for a specific import
///
/// This is `None` if the feature flag for `diagnostic::on_unknown` is disabled.
pub on_unknown_attr: Option<OnUnknownData>,
}
/// `Interned` is used because values of this type have "identity" and compare as unequal even if
/// they have the same contents.
pub(crate) type Import<'ra> = Interned<'ra, ImportData<'ra>>;
impl<'ra> ImportData<'ra> {
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 id(&self) -> Option<NodeId> {
match self.kind {
ImportKind::Single { id, .. }
| ImportKind::Glob { id, .. }
| ImportKind::ExternCrate { id, .. } => Some(id),
ImportKind::MacroUse { .. } | ImportKind::MacroExport => None,
}
}
pub(crate) fn def_id(&self) -> Option<LocalDefId> {
match self.kind {
ImportKind::Single { def_id, .. }
| ImportKind::Glob { def_id, .. }
| ImportKind::ExternCrate { def_id, .. } => Some(def_id),
ImportKind::MacroUse { .. } | ImportKind::MacroExport => None,
}
}
pub(crate) fn simplify(&self) -> Reexport {
match self.kind {
ImportKind::Single { def_id, .. } => Reexport::Single(def_id.to_def_id()),
ImportKind::Glob { def_id, .. } => Reexport::Glob(def_id.to_def_id()),
ImportKind::ExternCrate { def_id, .. } => Reexport::ExternCrate(def_id.to_def_id()),
ImportKind::MacroUse { .. } => Reexport::MacroUse,
ImportKind::MacroExport => Reexport::MacroExport,
}
}
fn summary(&self) -> ImportSummary {
ImportSummary {
vis: self.vis,
nearest_parent_mod: self.parent_scope.module.nearest_parent_mod().expect_local(),
is_single: matches!(self.kind, ImportKind::Single { .. }),
priv_macro_use: matches!(self.kind, ImportKind::MacroUse { warn_private: true }),
span: self.span,
}
}
}
/// Records information about the resolution of a name in a namespace of a module.
#[derive(Debug)]
pub(crate) struct NameResolution<'ra> {
/// 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: FxIndexSet<Import<'ra>>,
/// The non-glob declaration for this name, if it is known to exist.
pub non_glob_decl: Option<Decl<'ra>> = None,
/// The glob declaration for this name, if it is known to exist.
pub glob_decl: Option<Decl<'ra>> = None,
pub orig_ident_span: Span,
}
/// `Interned` is used because values of this type have "identity" and compare as unequal even if
/// they have the same contents.
pub(crate) type NameResolutionRef<'ra> = Interned<'ra, CmRefCell<NameResolution<'ra>>>;
impl<'ra> NameResolution<'ra> {
pub(crate) fn new(orig_ident_span: Span) -> Self {
NameResolution { single_imports: FxIndexSet::default(), orig_ident_span, .. }
}
/// Returns the best declaration if it is not going to change, and `None` if the best
/// declaration may still change to something else.
/// FIXME: this function considers `single_imports`, but not `unexpanded_invocations`, so
/// the returned declaration may actually change after expanding macros in the same module,
/// because of this fact we have glob overwriting (`select_glob_decl`). Consider using
/// `unexpanded_invocations` here and avoiding glob overwriting entirely, if it doesn't cause
/// code breakage in practice.
/// FIXME: relationship between this function and similar `DeclData::determined` is unclear.
pub(crate) fn determined_decl(&self) -> Option<Decl<'ra>> {
if self.non_glob_decl.is_some() {
self.non_glob_decl
} else if self.glob_decl.is_some() && self.single_imports.is_empty() {
self.glob_decl
} else {
None
}
}
pub(crate) fn best_decl(&self) -> Option<Decl<'ra>> {
self.non_glob_decl.or(self.glob_decl)
}
}
// module to keep the TLS private and only accessible through the function `enter_cycle_detector`.
pub(crate) mod cycle_detection {
use std::cell::RefCell;
use std::ptr;
use crate::{BindingKey, LocalModule};
thread_local!(
/// During import resolution, recursive imports can form cycles.
/// This set stores the active resolution stack for the current thread.
/// By keeping track of the module and `BindingKey` pair that identifies
/// the specific resolution.
///
/// The pointer is the interned address of a `Interned<'ra, ModuleData>` allocated
/// in the `Resolver Arenas` (lifetime `'ra`), it is thus stable and allows casting
/// to a `*const ()` for comparison. This is done because we can't use lifetimes
/// other than `'static` in thread local storage.
static ACTIVE_RESOLUTIONS: RefCell<Vec<(*const (), BindingKey)>> = Default::default();
);
pub(crate) struct ActiveResolutionGuard {
key: (*const (), BindingKey),
}
impl Drop for ActiveResolutionGuard {
fn drop(&mut self) {
ACTIVE_RESOLUTIONS.with_borrow_mut(|ar| {
// Only this guard is allowed to remove this key.
assert!(
Some(self.key) == ar.pop(),
"This guard should be the only one removing this key"
);
});
}
}
/// Returns `Err(())` if a cycle is detected, otherwise this returns a
/// guard that will remove the resolution when dropped.
pub(crate) fn enter_cycle_detector<'ra>(
module: LocalModule<'ra>,
binding_key: BindingKey,
) -> Result<ActiveResolutionGuard, ()> {
let module_key = ptr::from_ref(module.0.0).cast();
let key = (module_key, binding_key);
ACTIVE_RESOLUTIONS.with_borrow_mut(|ar| {
if ar.contains(&key) {
return Err(());
}
ar.push(key);
Ok(ActiveResolutionGuard { key })
})
}
}
/// 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)]
pub(crate) struct UnresolvedImportError {
pub(crate) span: Span,
pub(crate) label: Option<String>,
pub(crate) note: Option<String>,
pub(crate) suggestion: Option<Suggestion>,
pub(crate) candidates: Option<Vec<ImportSuggestion>>,
pub(crate) segment: Option<Ident>,
/// comes from `PathRes::Failed { module }`
pub(crate) module: Option<DefId>,
pub(crate) on_unknown_attr: Option<OnUnknownData>,
}
// 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: ImportSummary,
decl: Decl<'_>,
) -> Option<LocalDefId> {
match (import.is_single, &decl.kind) {
(true, DeclKind::Import { import: decl_import, .. })
if let ImportKind::ExternCrate { def_id, .. } = decl_import.kind
&& import.vis.is_public() =>
{
Some(def_id)
}
_ => None,
}
}
/// Removes identical import layers from two declarations.
fn remove_same_import<'ra>(d1: Decl<'ra>, d2: Decl<'ra>) -> (Decl<'ra>, Decl<'ra>) {
if let DeclKind::Import { import: import1, source_decl: d1_next } = d1.kind
&& let DeclKind::Import { import: import2, source_decl: d2_next } = d2.kind
&& import1 == import2
{
assert_eq!(d1.expansion, d2.expansion);
assert_eq!(d1.span, d2.span);
if d1.ambiguity.get() != d2.ambiguity.get() {
assert!(d1.ambiguity.get().is_some());
}
// Visibility of the new import declaration may be different,
// because it already incorporates the visibility of the source binding.
remove_same_import(d1_next, d2_next)
} else {
(d1, d2)
}
}
impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
pub(crate) fn import_decl_vis(&self, decl: Decl<'ra>, import: ImportSummary) -> Visibility {
self.import_decl_vis_ext(decl, import, false)
}
pub(crate) fn import_decl_vis_ext(
&self,
decl: Decl<'ra>,
import: ImportSummary,
min: bool,
) -> Visibility {
assert!(import.vis.is_accessible_from(import.nearest_parent_mod, self.tcx));
let decl_vis = if min { decl.min_vis() } else { decl.vis() };
let ord = decl_vis.partial_cmp(import.vis, self.tcx);
let extern_crate_hack = pub_use_of_private_extern_crate_hack(import, decl).is_some();
if ord == Some(Ordering::Less)
&& decl_vis.is_accessible_from(import.nearest_parent_mod, self.tcx)
&& !extern_crate_hack
{
// Imported declaration is less visible than the import, but is still visible
// from the current module, use the declaration's visibility.
decl_vis.expect_local()
} else {
// Good case - imported declaration is more visible than the import, or the same,
// use the import's visibility.
//
// Bad case - imported declaration is too private for the current module.
// It doesn't matter what visibility we choose here (except in the `PRIVATE_MACRO_USE`
// and `PUB_USE_OF_PRIVATE_EXTERN_CRATE` cases), because an error will be reported.
// Use import visibility to keep the all declaration visibilities in a module ordered.
if !min
&& matches!(ord, None | Some(Ordering::Less))
&& !extern_crate_hack
&& !import.priv_macro_use
{
let msg = format!("cannot extend visibility from {decl_vis:?} to {:?}", import.vis);
self.dcx().span_delayed_bug(import.span, msg);
}
import.vis
}
}
/// Given an import and the declaration that it points to,
/// create the corresponding import declaration.
pub(crate) fn new_import_decl(&self, decl: Decl<'ra>, import: Import<'ra>) -> Decl<'ra> {
let vis = self.import_decl_vis(decl, import.summary());
if let ImportKind::Glob { ref max_vis, .. } = import.kind
&& (vis == import.vis
|| max_vis.get().is_none_or(|max_vis| vis.greater_than(max_vis, self.tcx)))
{
// `set` can't fail because this can only happen during "write_import_resolutions"
max_vis.set(Some(vis), self)
}
self.arenas.alloc_decl(DeclData {
kind: DeclKind::Import { source_decl: decl, import },
ambiguity: CmCell::new(None),
span: import.span,
initial_vis: vis.to_mod_id(),
ambiguity_vis_max: CmCell::new(None),
ambiguity_vis_min: CmCell::new(None),
expansion: import.parent_scope.expansion,
parent_module: Some(import.parent_scope.module),
})
}
fn is_noise_0_7_0(&self, old_glob_decl: Decl<'ra>, glob_decl: Decl<'ra>) -> bool {
let DeclKind::Import { import: i1, .. } = glob_decl.kind else { unreachable!() };
let DeclKind::Import { import: i2, .. } = old_glob_decl.kind else { unreachable!() };
let [seg1, seg2] = &i1.module_path[..] else { return false };
if seg1.ident.name != kw::SelfLower || seg2.ident.name.as_str() != "perlin_surflet" {
return false;
}
let [seg1, seg2] = &i2.module_path[..] else { return false };
if seg1.ident.name != kw::SelfLower || seg2.ident.name.as_str() != "perlin" {
return false;
}
let Some(def_id1) = glob_decl.res().opt_def_id() else { return false };
let Some(def_id2) = old_glob_decl.res().opt_def_id() else { return false };
self.def_path_str(def_id1).ends_with("noise_fns::generators::perlin_surflet::Perlin")
&& self.def_path_str(def_id2).ends_with("noise_fns::generators::perlin::Perlin")
}
fn is_rustybuzz_0_4_0(&self, old_glob_decl: Decl<'ra>, glob_decl: Decl<'ra>) -> bool {
let DeclKind::Import { import: i1, .. } = glob_decl.kind else { unreachable!() };
let DeclKind::Import { import: i2, .. } = old_glob_decl.kind else { unreachable!() };
let [seg1, seg2] = &i1.module_path[..] else { return false };
if seg1.ident.name != kw::Super || seg2.ident.name.as_str() != "gsubgpos" {
return false;
}
let [seg1] = &i2.module_path[..] else { return false };
if seg1.ident.name != kw::Super {
return false;
}
let Some(def_id1) = glob_decl.res().opt_def_id() else { return false };
let Some(def_id2) = old_glob_decl.res().opt_def_id() else { return false };
self.def_path_str(def_id1).ends_with("tables::gsubgpos::Class")
&& self.def_path_str(def_id2).ends_with("ggg::Class")
}
fn is_pdf_0_9_0(&self, old_glob_decl: Decl<'ra>, glob_decl: Decl<'ra>) -> bool {
let DeclKind::Import { import: i1, .. } = glob_decl.kind else { unreachable!() };
let DeclKind::Import { import: i2, .. } = old_glob_decl.kind else { unreachable!() };
let [seg1, seg2] = &i1.module_path[..] else { return false };
if seg1.ident.name != kw::Crate || seg2.ident.name.as_str() != "content" {
return false;
}
let [seg1, seg2] = &i2.module_path[..] else { return false };
if seg1.ident.name != kw::Crate || seg2.ident.name.as_str() != "object" {
return false;
}
let Some(def_id1) = glob_decl.res().opt_def_id() else { return false };
let Some(def_id2) = old_glob_decl.res().opt_def_id() else { return false };
self.def_path_str(def_id1).ends_with("crate::content::Rect")
&& self.def_path_str(def_id2).ends_with("crate::object::types::Rect")
}
fn is_net2_0_2_39(&self, old_glob_decl: Decl<'ra>, glob_decl: Decl<'ra>) -> bool {
let DeclKind::Import { import: i1, .. } = glob_decl.kind else { unreachable!() };
let DeclKind::Import { import: i2, .. } = old_glob_decl.kind else { unreachable!() };
let [seg1, seg2, seg3, seg4] = &i1.module_path[..] else { return false };
if seg1.ident.name != kw::PathRoot
|| seg2.ident.name.as_str() != "winapi"
|| seg3.ident.name.as_str() != "shared"
|| seg4.ident.name.as_str() != "ws2def"
{
return false;
}
let [seg1, seg2, seg3, seg4] = &i2.module_path[..] else { return false };
if seg1.ident.name != kw::PathRoot
|| seg2.ident.name.as_str() != "winapi"
|| seg3.ident.name.as_str() != "um"
|| seg4.ident.name.as_str() != "winsock2"
{
return false;
}
let Some(def_id1) = glob_decl.res().opt_def_id() else { return false };
let Some(def_id2) = old_glob_decl.res().opt_def_id() else { return false };
self.def_path_str(def_id1).starts_with("winapi::shared::ws2def::")
&& self.def_path_str(def_id2).starts_with("winapi::um::winsock2::")
}
/// If `glob_decl` attempts to overwrite `old_glob_decl` in a module,
/// decide which one to keep.
fn select_glob_decl(&self, old_glob_decl: Decl<'ra>, glob_decl: Decl<'ra>) -> Decl<'ra> {
assert!(glob_decl.is_glob_import());
assert!(old_glob_decl.is_glob_import());
assert_ne!(glob_decl, old_glob_decl);
// `best_decl` with a given key in a module may be overwritten in a
// number of cases (all of them can be seen below in the `match` in `try_define_local`),
// all these overwrites will be re-fetched by glob imports importing
// from that module without generating new ambiguities.
// - A glob decl is overwritten by a non-glob decl arriving later.
// - A glob decl is overwritten by a glob decl re-fetching an
// overwritten decl from other module (the recursive case).
// Here we are detecting all such re-fetches and overwrite old decls
// with the re-fetched decls.
// This is probably incorrect in corner cases, and the outdated decls still get
// propagated to other places and get stuck there, but that's what we have at the moment.
let (old_deep_decl, deep_decl) = remove_same_import(old_glob_decl, glob_decl);
if deep_decl != glob_decl {
// Some import layers have been removed, need to overwrite.
assert_ne!(old_deep_decl, old_glob_decl);
assert!(!deep_decl.is_glob_import());
if let Some((old_ambig, _)) = old_glob_decl.ambiguity.get()
&& glob_decl.ambiguity.get().is_none()
{
// Do not lose glob ambiguities when re-fetching the glob.
glob_decl.ambiguity.set(Some((old_ambig, true)), self);
}
glob_decl
} else if glob_decl.res() != old_glob_decl.res() {
let warning = self.is_noise_0_7_0(old_glob_decl, glob_decl)
|| self.is_rustybuzz_0_4_0(old_glob_decl, glob_decl)
|| self.is_pdf_0_9_0(old_glob_decl, glob_decl)
|| self.is_net2_0_2_39(old_glob_decl, glob_decl);
old_glob_decl.ambiguity.set(Some((glob_decl, warning)), self);
old_glob_decl
} else if let old_vis = old_glob_decl.vis()
&& let vis = glob_decl.vis()
&& old_vis != vis
{
// We are glob-importing the same item but with a different visibility.
// All visibilities here are ordered because all of them are ancestors of `module`.
if vis.greater_than(old_vis, self.tcx) {
old_glob_decl.ambiguity_vis_max.set(Some(glob_decl), self);
} else if let old_min_vis = old_glob_decl.min_vis()
&& old_min_vis != vis
&& old_min_vis.greater_than(vis, self.tcx)
{
old_glob_decl.ambiguity_vis_min.set(Some(glob_decl), self);
}
old_glob_decl
} else if glob_decl.is_ambiguity_recursive() && !old_glob_decl.is_ambiguity_recursive() {
// Overwriting a non-ambiguous glob import with an ambiguous glob import.
old_glob_decl.ambiguity.set(Some((glob_decl, true)), self);
old_glob_decl
} else {
old_glob_decl
}
}
/// Attempt to put the declaration with the given name and namespace into the module,
/// and return existing declaration if there is a collision.
pub(crate) fn try_plant_decl_into_local_module(
&mut self,
ident: IdentKey,
orig_ident_span: Span,
ns: Namespace,
decl: Decl<'ra>,
) -> Result<(), Decl<'ra>> {
assert!(decl.ambiguity.get().is_none());
assert!(decl.ambiguity_vis_max.get().is_none());
assert!(decl.ambiguity_vis_min.get().is_none());
let module = decl.parent_module.unwrap().expect_local();
assert!(self.is_accessible_from(decl.vis(), module.to_module()));
let res = decl.res();
self.check_reserved_macro_name(ident.name, orig_ident_span, res);
// Even if underscore names cannot be looked up, we still need to add them to modules,
// because they can be fetched by glob imports from those modules, and bring traits
// into scope both directly and through glob imports.
let key = BindingKey::new_disambiguated(ident, ns, || {
module.underscore_disambiguator.update(self, |d| d + 1);
module.underscore_disambiguator.get()
});
self.update_local_resolution(module, key, orig_ident_span, |this, resolution| {
if res == Res::Err
&& let Some(old_decl) = resolution.best_decl()
&& old_decl.res() != Res::Err
{
// Do not override real declarations with `Res::Err`s from error recovery.
// FIXME: this special case shouldn't be necessary, but removing it triggers an ICE
// due to some other issues (#157406, tests/ui/imports/dummy-import-ice.rs).
return Ok(());
}
if decl.is_glob_import() {
resolution.glob_decl = Some(match resolution.glob_decl {
Some(old_decl) => this.select_glob_decl(old_decl, decl),
None => decl,
});
} else {
resolution.non_glob_decl = Some(match resolution.non_glob_decl {
Some(old_decl) => return Err(old_decl),
None => decl,
})
}
Ok(())
})
}
// 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_local_resolution<T, F>(
&mut self,
module: LocalModule<'ra>,
key: BindingKey,
orig_ident_span: Span,
f: F,
) -> T
where
F: FnOnce(&Resolver<'ra, 'tcx>, &mut NameResolution<'ra>) -> 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_or_default(module.to_module(), key, orig_ident_span)
.0
.borrow_mut(self);
let old_decl = resolution.determined_decl();
let old_vis = old_decl.map(|d| d.vis());
let t = f(self, resolution);
if let Some(binding) = resolution.determined_decl()
&& (old_decl != Some(binding) || old_vis != Some(binding.vis()))
{
(binding, t)
} else {
return t;
}
};
let Ok(glob_importers) = module.glob_importers.try_borrow_mut(self) else {
return t;
};
// Define or update `binding` in `module`s glob importers.
for import in glob_importers.iter() {
let mut ident = key.ident;
let scope = match ident
.ctxt
.update_unchecked(|ctxt| ctxt.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 import_decl = self.new_import_decl(binding, *import);
self.try_plant_decl_into_local_module(ident, orig_ident_span, key.ns, import_decl)
.expect("planting a glob cannot fail");
}
}
t
}
// Define a dummy resolution containing a `Res::Err` as a placeholder for a failed
// or indeterminate resolution, also mark such failed imports as used to avoid duplicate diagnostics.
fn import_dummy_binding(&mut self, import: Import<'ra>, is_indeterminate: bool) {
if let ImportKind::Single { target, ref decls, .. } = import.kind {
if !(is_indeterminate || decls.iter().all(|d| d.get().decl().is_none())) {
return; // Has resolution, do not create the dummy binding
}
let dummy_decl = self.dummy_decl;
let dummy_decl = self.new_import_decl(dummy_decl, import);
self.per_ns_mut(|this, ns| {
let ident = IdentKey::new(target);
// This can fail, dummies are inserted only in non-occupied slots.
let _ = this.try_plant_decl_into_local_module(ident, target.span, ns, dummy_decl);
// Don't remove underscores from `single_imports`, they were never added.
if target.name != kw::Underscore {
let key = BindingKey::new(ident, ns);
this.update_local_resolution(
import.parent_scope.module.expect_local(),
key,
target.span,
|_, resolution| {
resolution.single_imports.swap_remove(&import);
},
)
}
});
self.record_use(target, dummy_decl, Used::Other);
} else if import.imported_module.get().is_none() {
self.import_use_map.insert(import, Used::Other);
if let Some(id) = import.id() {
self.used_imports.insert(id);
}
}
}
// Import resolution
//
// This is a batched fixed-point algorithm. Each import is resolved in
// isolation, with any resolutions collected for later.
// After a full pass over the current set of `indeterminate_imports`,
// the collected resolutions are committed together. The process
// repeats until either no imports remain or no further progress can
// be 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;
let mut imports_to_resolve = mem::take(&mut self.indeterminate_imports);
// SAFETY: This is a "top-level" function used by the macro expansion code, unless some
// weird thing is done, all `tracked` borrows done in the previous call of
// `resolve_imports` are dropped when that call ended.
unsafe { self.speculative_flag.set(true) };
rustc_data_structures::sync::par_for_each_slice(
&mut imports_to_resolve,
|(import, resolution, indeterminate_count)| {
(*resolution, *indeterminate_count) = self.resolve_import(*import);
},
);
// SAFETY: All `untracked` borrows are dropped after the `par_for_each_slice` call,
// as they cannot escape since they are tied to the `CmRefCell` they borrowed from.
//
// Note: Some `CmRefCell`s are arena allocated and thus have the `'ra` lifetime,
// allowing these borrows to escape, but that does not and should not happen.
unsafe { self.speculative_flag.set(false) };
self.write_import_resolutions(&imports_to_resolve);
self.indeterminate_imports = imports_to_resolve
.extract_if(.., |(_, _, count)| {
indeterminate_count += *count;
*count > 0
})
.collect();
self.determined_imports.extend(imports_to_resolve.into_iter().map(|(i, _, _)| i));
}
}
fn write_import_resolutions(
&mut self,
import_resolutions: &[(Import<'ra>, Option<ImportResolution<'ra>>, usize)],
) {
for &(import, ref resolution, _) in import_resolutions {
let Some(ImportResolution { imported_module, .. }) = resolution else {
continue;
};
import.imported_module.set(Some(*imported_module), self);
if import.is_glob()
&& let ModuleOrUniformRoot::Module(module) = imported_module
&& import.parent_scope.module != *module
&& module.is_local()
{
module.glob_importers.borrow_mut(self).push(import);
}
}
for &(import, ref resolution, _) in import_resolutions {
let Some(ImportResolution { imported_module, kind: resolution_kind }) = resolution
else {
continue;
};
match (&import.kind, resolution_kind) {
(
ImportKind::Single { target, decls, .. },
ImportResolutionKind::Single(import_decls),
) => {
self.per_ns_mut(|this, ns| {
match import_decls[ns] {
PendingDecl::Ready(Some(decl)) => {
// We need the `target`, `source` can be extracted.
let import_decl = this.new_import_decl(decl, import);
if import_decl.is_assoc_item()
&& !this.features.import_trait_associated_functions()
{
feature_err(
this.tcx.sess,
sym::import_trait_associated_functions,
import.span,
"`use` associated items of traits is unstable",
)
.emit();
}
this.plant_decl_into_local_module(
IdentKey::new(*target),
target.span,
ns,
import_decl,
);
decls[ns].set(PendingDecl::Ready(Some(import_decl)), this);
}
PendingDecl::Ready(None) => {
// Don't remove underscores from `single_imports`, they were never added.
if target.name != kw::Underscore {
let key = BindingKey::new(IdentKey::new(*target), ns);
this.update_local_resolution(
import.parent_scope.module.expect_local(),
key,
target.span,
|_, resolution| {
resolution.single_imports.swap_remove(&import);
},
);
}
decls[ns].set(PendingDecl::Ready(None), this);
}
PendingDecl::Pending => {}
}
});
}
(ImportKind::Glob { id, .. }, ImportResolutionKind::Glob(imported_decls)) => {
let ModuleOrUniformRoot::Module(module) = imported_module else {
self.dcx().emit_err(CannotGlobImportAllCrates { span: import.span });
continue;
};
if module.is_trait() && !self.features.import_trait_associated_functions() {
feature_err(
self.tcx.sess,
sym::import_trait_associated_functions,
import.span,
"`use` associated items of traits is unstable",
)
.emit();
}
for (binding, key, orig_ident_span) in imported_decls {
let import_decl = self.new_import_decl(*binding, import);
let _ = self
.try_plant_decl_into_local_module(
key.ident,
*orig_ident_span,
key.ns,
import_decl,
)
.expect("planting a glob cannot fail");
}
self.record_partial_res(*id, PartialRes::new(module.res().unwrap()));
}
// Something weird happened, which shouldn't have happened.
_ => unreachable!("mismatched import and resolution kind"),
}
}
}
pub(crate) fn finalize_imports(&mut self) {
let mut module_children = Default::default();
let mut ambig_module_children = Default::default();
for module in &self.local_modules {
self.finalize_resolutions_in(*module, &mut module_children, &mut ambig_module_children);
}
self.module_children = module_children;
self.ambig_module_children = ambig_module_children;
let mut seen_spans = FxHashSet::default();
let mut errors = vec![];
let mut prev_root_id: NodeId = NodeId::ZERO;
let determined_imports = mem::take(&mut self.determined_imports);
let indeterminate_imports = mem::take(&mut self.indeterminate_imports);
let mut glob_error = false;
for (is_indeterminate, import) in determined_imports
.iter()
.map(|i| (false, i))
.chain(indeterminate_imports.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, is_indeterminate);
let Some(err) = unresolved_import_error else { continue };
glob_error |= import.is_glob();
if let ImportKind::Single { source, ref decls, .. } = import.kind
&& source.name == kw::SelfLower
// Silence `unresolved import` error if E0429 is already emitted
&& let PendingDecl::Ready(None) = decls.value_ns.get()
{
continue;
}
if prev_root_id != NodeId::ZERO && prev_root_id != import.root_id && !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, glob_error);
errors = vec![];
}
if seen_spans.insert(err.span) {
errors.push((*import, err));
prev_root_id = import.root_id;
}
}
if self.cstore().had_extern_crate_load_failure() {
self.tcx.sess.dcx().abort_if_errors();
}
if !errors.is_empty() {
self.throw_unresolved_import_error(errors, glob_error);
return;
}
for (import, _, _) in &indeterminate_imports {
let path = import_path_to_string(
&import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
&import.kind,
import.span,
);
// FIXME: there should be a better way of doing this than
// formatting this as a string then checking for `::`
if path.contains("::") {
let err = UnresolvedImportError {
span: import.span,
label: None,
note: None,
suggestion: None,
candidates: None,
segment: None,
module: None,
on_unknown_attr: import.on_unknown_attr.clone(),
};
errors.push((*import, err))
}
}
if !errors.is_empty() {
self.throw_unresolved_import_error(errors, glob_error);
}
}
pub(crate) fn lint_reexports(&mut self, exported_ambiguities: FxHashSet<Decl<'ra>>) {
for module in &self.local_modules {
for (key, resolution) in self.resolutions(module.to_module()).iter() {
let resolution = resolution.borrow(self);
let Some(binding) = resolution.best_decl() else { continue };
// Report "cannot reexport" errors for exotic cases involving macros 2.0
// privacy bending or invariant-breaking code under deprecation lints.
for decl in [resolution.non_glob_decl, resolution.glob_decl] {
if let Some(decl) = decl
&& let DeclKind::Import { source_decl, import } = decl.kind
// FIXME: Do not check visibility-ambiguous imports for now. To check them
// properly we need to preserve all imports in ambiguous glob sets and
// check them all individually.
&& decl.ambiguity_vis_max.get().is_none()
{
// The source entity is too private to be reexported
// with the given import declaration's visibility.
let ord = source_decl.vis().partial_cmp(decl.vis(), self.tcx);
if matches!(ord, None | Some(Ordering::Less)) {
let ident = match import.kind {
ImportKind::Single { source, .. } => source,
_ => key.ident.orig(resolution.orig_ident_span),
};
if let Some(lint) =
self.report_cannot_reexport(import, source_decl, ident, key.ns)
{
self.lint_buffer.add_early_lint(lint);
}
}
}
}
if let DeclKind::Import { import, .. } = binding.kind
&& let Some((amb_binding, _)) = binding.ambiguity.get()
&& binding.res() != Res::Err
&& exported_ambiguities.contains(&binding)
{
self.lint_buffer.buffer_lint(
AMBIGUOUS_GLOB_REEXPORTS,
import.root_id,
import.root_span,
diagnostics::AmbiguousGlobReexports {
name: key.ident.name.to_string(),
namespace: key.ns.descr().to_string(),
first_reexport: import.root_span,
duplicate_reexport: amb_binding.span,
},
);
}
if let Some(glob_decl) = resolution.glob_decl
&& resolution.non_glob_decl.is_some()
{
if binding.res() != Res::Err
&& glob_decl.res() != Res::Err
&& let DeclKind::Import { import: glob_import, .. } = glob_decl.kind
&& let Some(glob_import_def_id) = glob_import.def_id()
&& self.effective_visibilities.is_exported(glob_import_def_id)
&& glob_decl.vis().is_public()
&& !binding.vis().is_public()
{
let binding_id = match binding.kind {
DeclKind::Def(res) => {
Some(self.def_id_to_node_id(res.def_id().expect_local()))
}
DeclKind::Import { import, .. } => import.id(),
};
if let Some(binding_id) = binding_id {
self.lint_buffer.buffer_lint(
HIDDEN_GLOB_REEXPORTS,
binding_id,
binding.span,
diagnostics::HiddenGlobReexports {
name: key.ident.name.to_string(),
namespace: key.ns.descr().to_owned(),
glob_reexport: glob_decl.span,
private_item: binding.span,
},
);
}
}
}
if let DeclKind::Import { import, .. } = binding.kind
&& let Some(binding_id) = import.id()
&& let import_def_id = import.def_id().unwrap()
&& self.effective_visibilities.is_exported(import_def_id)
&& let Res::Def(reexported_kind, reexported_def_id) = binding.res()
&& !matches!(reexported_kind, DefKind::Ctor(..))
&& !reexported_def_id.is_local()
&& self.tcx.is_private_dep(reexported_def_id.krate)
{
self.lint_buffer.buffer_lint(
EXPORTED_PRIVATE_DEPENDENCIES,
binding_id,
binding.span,
crate::diagnostics::ReexportPrivateDependency {
name: key.ident.name,
kind: binding.res().descr(),
krate: self.tcx.crate_name(reexported_def_id.krate),
},
);
}
}
}
}
/// Attempts to resolve the given import, returning:
/// - `0` means its resolution is determined.
/// - Other values mean that indeterminate exists under certain namespaces.
///
/// Meanwhile, if resolution is successful, its result is returned.
fn resolve_import(&self, import: Import<'ra>) -> (Option<ImportResolution<'ra>>, usize) {
debug!(
"(resolving import for module) resolving import `{}::{}` in `{}`",
Segment::names_to_string(&import.module_path),
import_kind_to_string(&import.kind),
module_to_string(import.parent_scope.module).unwrap_or_else(|| "???".to_string()),
);
let module = if let Some(module) = import.imported_module.get() {
module
} else {
let path_res = self.cm().maybe_resolve_path(
&import.module_path,
None,
&import.parent_scope,
Some(import),
);
match path_res {
PathResult::Module(module) => module,
PathResult::Indeterminate => return (None, 3),
PathResult::NonModule(..) | PathResult::Failed { .. } => return (None, 0),
}
};
let (source, bindings) = match import.kind {
ImportKind::Single { source, ref decls, .. } => (source, decls),
ImportKind::Glob { .. } => {
let import_resolution = ImportResolution {
imported_module: module,
kind: self.resolve_glob_import(import, module),
};
return (Some(import_resolution), 0);
}
_ => unreachable!(),
};
let mut decls = PerNS::default();
let mut indeterminate_count = 0;
self.per_ns(|this, ns| {
if bindings[ns].get() != PendingDecl::Pending {
return;
};
let binding_result = this.cm().maybe_resolve_ident_in_module(
module,
source,
ns,
&import.parent_scope,
Some(import),
);
let pending_decl = match binding_result {
Ok(binding) => PendingDecl::Ready(Some(binding)),
Err(Determinacy::Determined) => PendingDecl::Ready(None),
Err(Determinacy::Undetermined) => {
indeterminate_count += 1;
PendingDecl::Pending
}
};
decls[ns] = pending_decl;
});
let import_resolution =
ImportResolution { imported_module: module, kind: ImportResolutionKind::Single(decls) };
(Some(import_resolution), 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: Import<'ra>) -> Option<UnresolvedImportError> {
let ignore_decl = match &import.kind {
ImportKind::Single { decls, .. } => decls[TypeNS].get().decl(),
_ => None,
};
let ambiguity_errors_len = |errors: &Vec<AmbiguityError<'_>>| {
errors.iter().filter(|error| error.warning.is_none()).count()
};
let prev_ambiguity_errors_len = ambiguity_errors_len(&self.ambiguity_errors);
let finalize = Finalize::with_root_span(import.root_id, import.span, import.root_span);
// We'll provide more context to the privacy errors later, up to `len`.
let privacy_errors_len = self.privacy_errors.len();
let path_res = self.cm_mut().resolve_path(
&import.module_path,
None,
&import.parent_scope,
Some(finalize),
ignore_decl,
Some(import),
);
let no_ambiguity =
ambiguity_errors_len(&self.ambiguity_errors) == prev_ambiguity_errors_len;
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 module != initial_module && no_ambiguity && !self.issue_145575_hack_applied {
span_bug!(import.span, "inconsistent resolution for an import");
}
} else if self.privacy_errors.is_empty() {
self.dcx()
.create_err(CannotDetermineImportResolution { span: import.span })
.emit();
}
module
}
PathResult::Failed {
is_error_from_last_segment: false,
span,
segment,
label,
suggestion,
module,
error_implied_by_parse_error: _,
message,
note: _,
} => {
if no_ambiguity {
if !self.issue_145575_hack_applied {
assert!(import.imported_module.get().is_none());
}
self.report_error(
span,
ResolutionError::FailedToResolve {
segment: segment.name,
label,
suggestion,
module,
message,
},
);
}
return None;
}
PathResult::Failed {
is_error_from_last_segment: true,
span,
label,
suggestion,
module,
segment,
note,
..
} => {
if no_ambiguity {
if !self.issue_145575_hack_applied {
assert!(import.imported_module.get().is_none());
}
let module = if let Some(ModuleOrUniformRoot::Module(m)) = module {
m.opt_def_id()
} else {
None
};
let err = match self
.make_path_suggestion(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,
segment: Some(segment),
module,
on_unknown_attr: import.on_unknown_attr.clone(),
},
None => UnresolvedImportError {
span,
label: Some(label),
note,
suggestion,
candidates: None,
segment: Some(segment),
module,
on_unknown_attr: import.on_unknown_attr.clone(),
},
};
return Some(err);
}
return None;
}
PathResult::NonModule(partial_res) => {
if no_ambiguity && partial_res.full_res() != Some(Res::Err) {
// Check if there are no ambiguities and the result is not dummy.
assert!(import.imported_module.get().is_none());
}
// The error was already reported earlier.
return None;
}
PathResult::Indeterminate => unreachable!(),
};
let (ident, target, bindings, import_id) = match import.kind {
ImportKind::Single { source, target, ref decls, id, .. } => (source, target, decls, id),
ImportKind::Glob { ref max_vis, id, def_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::dummy()));
self.lint_if_path_starts_with_module(finalize, &full_path, None);
}
if let ModuleOrUniformRoot::Module(module) = module
&& 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,
segment: None,
module: None,
on_unknown_attr: None,
});
}
if let Some(max_vis) = max_vis.get()
&& import.vis.greater_than(max_vis, self.tcx)
{
self.lint_buffer.buffer_lint(
UNUSED_IMPORTS,
id,
import.span,
crate::diagnostics::RedundantImportVisibility {
span: import.span,
help: (),
max_vis: max_vis.to_string(def_id, self.tcx),
import_vis: import.vis.to_string(def_id, self.tcx),
},
);
}
return None;
}
_ => unreachable!(),
};
if self.privacy_errors.len() != privacy_errors_len {
// Get the Res for the last element, so that we can point to alternative ways of
// importing it if available.
let mut path = import.module_path.clone();
path.push(Segment::from_ident(ident));
if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = self
.cm_mut()
.resolve_path(&path, None, &import.parent_scope, Some(finalize), ignore_decl, None)
{
let res = module.res().map(|r| (r, ident));
for error in &mut self.privacy_errors[privacy_errors_len..] {
error.outermost_res = res;
}
} else {
// The final item is not a module (e.g., a struct, function, or macro).
// Resolve it directly in the parent module to get its Res, so
// `report_privacy_error()` can search for public re-export paths.
for ns in [TypeNS, ValueNS, MacroNS] {
if let Ok(binding) = self.cm().resolve_ident_in_module(
module,
ident,
ns,
&import.parent_scope,
None,
ignore_decl,
None,
) {
let res = binding.res();
for error in &mut self.privacy_errors[privacy_errors_len..] {
error.outermost_res = Some((res, ident));
}
break;
}
}
}
}
let mut all_ns_err = true;
self.per_ns_mut(|this, ns| {
let binding = this.cm_mut().resolve_ident_in_module(
module,
ident,
ns,
&import.parent_scope,
Some(Finalize {
report_private: false,
import: Some(import.summary()),
..finalize
}),
bindings[ns].get().decl(),
Some(import),
);
match binding {
Ok(binding) => {
// Consistency checks, analogous to `finalize_macro_resolutions`.
let initial_res = bindings[ns].get().decl().map(|binding| {
let initial_binding = binding.import_source();
all_ns_err = false;
if target.name == kw::Underscore
&& initial_binding.is_extern_crate()
&& !initial_binding.is_import()
{
let used = if import.module_path.is_empty() {
Used::Scope
} else {
Used::Other
};
this.record_use(ident, binding, used);
}
initial_binding.res()
});
let res = binding.res();
let has_ambiguity_error =
this.ambiguity_errors.iter().any(|error| error.warning.is_none());
if res == Res::Err || has_ambiguity_error {
this.dcx()
.span_delayed_bug(import.span, "some error happened for an import");
return;
}
if let Some(initial_res) = initial_res {
if res != initial_res && !this.issue_145575_hack_applied {
span_bug!(import.span, "inconsistent resolution for an import");
}
} else if this.privacy_errors.is_empty() {
this.dcx()
.create_err(CannotDetermineImportResolution { span: import.span })
.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_mut(|this, ns| {
let binding = this.cm_mut().resolve_ident_in_module(
module,
ident,
ns,
&import.parent_scope,
Some(finalize),
None,
None,
);
if binding.is_ok() {
all_ns_failed = false;
}
});
return if all_ns_failed {
let names = match module {
ModuleOrUniformRoot::Module(module) => {
self.resolutions(module)
.iter()
.filter_map(|(BindingKey { ident: i, .. }, resolution)| {
if i.name == ident.name {
return None;
} // Never suggest the same name
if i.name == kw::Underscore {
return None;
} // `use _` is never valid
let resolution = resolution.borrow(self);
if let Some(name_binding) = resolution.best_decl() {
match name_binding.kind {
DeclKind::Import { source_decl, .. } => {
match source_decl.kind {
// Never suggest names that previously could not
// be resolved.
DeclKind::Def(Res::Err) => None,
_ => Some(i.name),
}
}
_ => Some(i.name),
}
} else if resolution.single_imports.is_empty() {
None
} else {
Some(i.name)
}
})
.collect()
}
_ => Vec::new(),
};
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),
};
// If importing of trait asscoiated items is enabled, an also find an
// `Enum`, then note that inherent associated items cannot be imported.
let note = if self.features.import_trait_associated_functions()
&& let PathResult::Module(ModuleOrUniformRoot::Module(m)) = path_res
&& let Some(Res::Def(DefKind::Enum, _)) = m.res()
{
note.or(Some(
"cannot import inherent associated items, only trait associated items"
.to_string(),
))
} else {
note
};
let label = match module {
ModuleOrUniformRoot::Module(module) => {
let module_str = module_to_string(module);
if let Some(module_str) = module_str {
format!("no `{ident}` in `{module_str}`")
} else {
format!("no `{ident}` in the root")
}
}
_ => {
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 `{ident}` in the root")
}
}
};
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
},
module: import.imported_module.get().and_then(|module| {
if let ModuleOrUniformRoot::Module(m) = module {
m.opt_def_id()
} else {
None
}
}),
segment: Some(ident),
on_unknown_attr: import.on_unknown_attr.clone(),
})
} else {
// `resolve_ident_in_module` reported a privacy error.
None
};
}
let mut reexport_error = None;
let mut any_successful_reexport = false;
self.per_ns(|this, ns| {
let Some(binding) = bindings[ns].get().decl() else {
return;
};
if import.vis.greater_than(binding.vis(), this.tcx) {
// In isolation, a declaration like this is not an error, but if *all* 1-3
// declarations introduced by the import are more private than the import item's
// nominal visibility, then it's an error.
reexport_error = Some((ns, binding.import_source()));
} else {
any_successful_reexport = true;
}
});
if !any_successful_reexport {
let (ns, binding) = reexport_error.unwrap();
if let Some(lint) = self.report_cannot_reexport(import, binding, ident, ns) {
self.lint_buffer.add_early_lint(lint);
}
}
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_mut(|this, ns| {
if let Some(binding) = bindings[ns].get().decl().map(|b| b.import_source()) {
this.lint_if_path_starts_with_module(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_mut(|this, ns| {
if let Some(binding) = bindings[ns].get().decl().map(|b| b.import_source()) {
this.owners.get_mut(&import_id).unwrap().import_res[ns] = Some(binding.res());
}
});
debug!("(resolving single import) successfully resolved import");
None
}
fn report_cannot_reexport(
&self,
import: Import<'ra>,
decl: Decl<'ra>,
ident: Ident,
ns: Namespace,
) -> Option<BufferedEarlyLint> {
let crate_private_reexport = match decl.vis() {
Visibility::Restricted(mod_id) if mod_id.is_top_level_module() => true,
_ => false,
};
if let Some(extern_crate_id) = pub_use_of_private_extern_crate_hack(import.summary(), decl)
{
let ImportKind::Single { id, .. } = import.kind else { unreachable!() };
let sugg = self.tcx.source_span(extern_crate_id).shrink_to_lo();
let diagnostic = crate::diagnostics::PrivateExternCrateReexport { ident, sugg };
return Some(BufferedEarlyLint {
lint_id: LintId::of(PUB_USE_OF_PRIVATE_EXTERN_CRATE),
node_id: id,
span: Some(import.span.into()),
diagnostic: diagnostic.into(),
});
} else if ns == TypeNS {
let err = if crate_private_reexport {
self.dcx().create_err(CannotBeReexportedCratePublicNS { span: import.span, ident })
} else {
self.dcx().create_err(CannotBeReexportedPrivateNS { span: import.span, ident })
};
err.emit();
} else {
let mut err = if crate_private_reexport {
self.dcx().create_err(CannotBeReexportedCratePublic { span: import.span, ident })
} else {
self.dcx().create_err(CannotBeReexportedPrivate { span: import.span, ident })
};
match decl.kind {
// exclude decl_macro
DeclKind::Def(Res::Def(DefKind::Macro(_), def_id))
if let SyntaxExtensionKind::MacroRules(mr) =
&self.get_macro_by_def_id(def_id).kind
&& mr.is_macro_rules() =>
{
err.subdiagnostic(ConsiderAddingMacroExport { span: decl.span });
err.subdiagnostic(ConsiderMarkingAsPubCrate { vis_span: import.vis_span });
}
_ => {
err.subdiagnostic(ConsiderMarkingAsPub { span: import.span, ident });
}
}
err.emit();
}
None
}
pub(crate) fn check_for_redundant_imports(&mut self, import: Import<'ra>) -> bool {
// This function is only called for single imports.
let ImportKind::Single { source, target, ref decls, id, def_id, .. } = import.kind else {
unreachable!()
};
// Skip if the import is of the form `use source as target` and source != target.
if source != target {
return false;
}
// Skip if the import was produced by a macro.
if import.parent_scope.expansion != LocalExpnId::ROOT {
return false;
}
// Skip if we are inside a named module (in contrast to an anonymous
// module defined by a block).
// Skip if the import is public or was used through non scope-based resolution,
// e.g. through a module-relative path.
if self.import_use_map.get(&import) == Some(&Used::Other)
|| self.effective_visibilities.is_exported(def_id)
{
return false;
}
let mut is_redundant = true;
let mut redundant_span = PerNS { value_ns: None, type_ns: None, macro_ns: None };
self.per_ns(|this, ns| {
let binding = decls[ns].get().decl().map(|b| b.import_source());
if is_redundant && let Some(binding) = binding {
if binding.res() == Res::Err {
return;
}
match this.cm().resolve_ident_in_scope_set(
target,
ScopeSet::All(ns),
&import.parent_scope,
None,
decls[ns].get().decl(),
None,
) {
Ok(other_binding) => {
is_redundant = binding.res() == other_binding.res()
&& !other_binding.is_ambiguity_recursive();
if is_redundant {
redundant_span[ns] =
Some((other_binding.span, other_binding.is_import()));
}
}
Err(_) => is_redundant = false,
}
}
});
if is_redundant && !redundant_span.is_empty() {
let mut redundant_spans: Vec<_> = redundant_span.present_items().collect();
redundant_spans.sort();
redundant_spans.dedup();
self.lint_buffer.dyn_buffer_lint(
REDUNDANT_IMPORTS,
id,
import.span,
move |dcx, level| {
let ident = source;
let subs = redundant_spans
.into_iter()
.map(|(span, is_imported)| match (span.is_dummy(), is_imported) {
(false, true) => {
diagnostics::RedundantImportSub::ImportedHere { span, ident }
}
(false, false) => {
diagnostics::RedundantImportSub::DefinedHere { span, ident }
}
(true, true) => {
diagnostics::RedundantImportSub::ImportedPrelude { span, ident }
}
(true, false) => {
diagnostics::RedundantImportSub::DefinedPrelude { span, ident }
}
})
.collect();
diagnostics::RedundantImport { subs, ident }.into_diag(dcx, level)
},
);
return true;
}
false
}
fn resolve_glob_import(
&self,
import: Import<'ra>,
imported_module: ModuleOrUniformRoot<'ra>,
) -> ImportResolutionKind<'ra> {
let import_bindings = match imported_module {
ModuleOrUniformRoot::Module(module) if module != import.parent_scope.module => self
.resolutions(module)
.iter()
.filter_map(|(key, resolution)| {
let res = resolution.borrow(self);
let decl = res.determined_decl()?;
let mut key = *key;
let scope = match key.ident.ctxt.update_unchecked(|ctxt| {
ctxt.reverse_glob_adjust(module.expansion, import.span)
}) {
Some(Some(def)) => self.expn_def_scope(def),
Some(None) => import.parent_scope.module,
None => return None,
};
self.is_accessible_from(decl.vis(), scope).then_some((
decl,
key,
res.orig_ident_span,
))
})
.collect::<Vec<_>>(),
// Errors are reported in `write_imports_resolutions`
_ => vec![],
};
ImportResolutionKind::Glob(import_bindings)
}
// Hack for the `rust_embed` regression observed in the crater run of #145108.
fn rust_embed_hack(&self, module: LocalModule<'ra>, decl: Decl<'ra>) -> bool {
// We are looking for this pattern:
// ```rust
// #[macro_use]
// extern crate rust_embed_impl;
// pub use rust_embed_impl::*;
//
// pub use RustEmbed as Embed;
// ```
if let DeclKind::Import { source_decl, import } = decl.kind
// Check that `decl` is the re-export: "pub use RustEmbed as Embed;"
&& let ImportKind::Single { source, .. } = import.kind
&& source.name == sym::RustEmbed
// make sure that the import points to the #[macro_use] import
&& let DeclKind::Import { import, .. } = source_decl.kind
&& matches!(import.kind, ImportKind::MacroUse { .. })
&& self.macro_use_prelude.contains_key(&source.name) // and that the name actually exists in the macro_use_prelude
// Then check that `RustEmbed` exists in the modules Macro namespace.
&& let Some(y_decl) = self
.resolution(module.to_module(), BindingKey::new(IdentKey::new(source), MacroNS))
.and_then(|res| res.best_decl())
// which comes from "pub use rust_embed_impl::*"
&& y_decl.is_glob_import()
&& y_decl.vis().is_public()
{
return true;
}
false
}
// Miscellaneous post-processing, including recording re-exports,
// reporting conflicts, and reporting unresolved imports.
fn finalize_resolutions_in(
&self,
module: LocalModule<'ra>,
module_children: &mut LocalDefIdMap<Vec<ModChild>>,
ambig_module_children: &mut LocalDefIdMap<Vec<AmbigModChild>>,
) {
// Since import resolution is finished, globs will not define any more names.
*module.globs.borrow_mut(self) = Vec::new();
let Some(def_id) = module.opt_def_id() else { return };
let mut children = Vec::new();
let mut ambig_children = Vec::new();
module.to_module().for_each_child(self, |this, ident, orig_ident_span, _, decl| {
let res = decl.res().expect_non_local();
if res != def::Res::Err {
let vis = if this.rust_embed_hack(module, decl) {
Visibility::Public
} else {
decl.vis()
};
let ident = ident.orig(orig_ident_span);
let child = |reexport_chain| ModChild { ident, res, vis, reexport_chain };
if let Some((ambig_binding1, ambig_binding2)) = decl.descent_to_ambiguity() {
let main = child(ambig_binding1.reexport_chain());
let second = ModChild {
ident,
res: ambig_binding2.res().expect_non_local(),
vis: ambig_binding2.vis(),
reexport_chain: ambig_binding2.reexport_chain(),
};
ambig_children.push(AmbigModChild { main, second })
} else {
children.push(child(decl.reexport_chain()));
}
}
});
if !children.is_empty() {
module_children.insert(def_id.expect_local(), children);
}
if !ambig_children.is_empty() {
ambig_module_children.insert(def_id.expect_local(), ambig_children);
}
}
}
pub(crate) 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))
} 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)),
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(),
}
}