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rust/compiler/rustc_resolve/src/diagnostics.rs

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use rustc_ast::expand::StrippedCfgItem;
use rustc_ast::ptr::P;
use rustc_ast::visit::{self, Visitor};
use rustc_ast::{self as ast, Crate, ItemKind, ModKind, NodeId, Path, CRATE_NODE_ID};
use rustc_ast::{MetaItemKind, NestedMetaItem};
use rustc_ast_pretty::pprust;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::{pluralize, report_ambiguity_error, struct_span_err, SuggestionStyle};
use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan};
use rustc_feature::BUILTIN_ATTRIBUTES;
use rustc_hir::def::Namespace::{self, *};
use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind, PerNS};
use rustc_hir::def_id::{DefId, CRATE_DEF_ID};
use rustc_hir::PrimTy;
use rustc_middle::bug;
use rustc_middle::ty::TyCtxt;
use rustc_session::lint::builtin::ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE;
use rustc_session::lint::builtin::AMBIGUOUS_GLOB_IMPORTS;
use rustc_session::lint::builtin::MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS;
use rustc_session::lint::{AmbiguityErrorDiag, BuiltinLintDiagnostics};
use rustc_session::Session;
use rustc_span::edit_distance::find_best_match_for_name;
use rustc_span::edition::Edition;
use rustc_span::hygiene::MacroKind;
use rustc_span::source_map::SourceMap;
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{BytePos, Span, SyntaxContext};
use thin_vec::ThinVec;
use crate::errors::{
AddedMacroUse, ChangeImportBinding, ChangeImportBindingSuggestion, ConsiderAddingADerive,
ExplicitUnsafeTraits,
};
use crate::imports::{Import, ImportKind};
use crate::late::{PatternSource, Rib};
use crate::path_names_to_string;
use crate::{errors as errs, BindingKey};
use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, BindingError, Finalize};
use crate::{HasGenericParams, MacroRulesScope, Module, ModuleKind, ModuleOrUniformRoot};
use crate::{LexicalScopeBinding, NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet};
use crate::{Segment, UseError};
#[cfg(test)]
mod tests;
type Res = def::Res<ast::NodeId>;
/// A vector of spans and replacements, a message and applicability.
pub(crate) type Suggestion = (Vec<(Span, String)>, String, Applicability);
/// Potential candidate for an undeclared or out-of-scope label - contains the ident of a
/// similarly named label and whether or not it is reachable.
pub(crate) type LabelSuggestion = (Ident, bool);
#[derive(Debug)]
pub(crate) enum SuggestionTarget {
/// The target has a similar name as the name used by the programmer (probably a typo)
SimilarlyNamed,
/// The target is the only valid item that can be used in the corresponding context
SingleItem,
}
#[derive(Debug)]
pub(crate) struct TypoSuggestion {
pub candidate: Symbol,
/// The source location where the name is defined; None if the name is not defined
/// in source e.g. primitives
pub span: Option<Span>,
pub res: Res,
pub target: SuggestionTarget,
}
impl TypoSuggestion {
pub(crate) fn typo_from_ident(ident: Ident, res: Res) -> TypoSuggestion {
Self {
candidate: ident.name,
span: Some(ident.span),
res,
target: SuggestionTarget::SimilarlyNamed,
}
}
pub(crate) fn typo_from_name(candidate: Symbol, res: Res) -> TypoSuggestion {
Self { candidate, span: None, res, target: SuggestionTarget::SimilarlyNamed }
}
pub(crate) fn single_item_from_ident(ident: Ident, res: Res) -> TypoSuggestion {
Self {
candidate: ident.name,
span: Some(ident.span),
res,
target: SuggestionTarget::SingleItem,
}
}
}
/// A free importable items suggested in case of resolution failure.
#[derive(Debug, Clone)]
pub(crate) struct ImportSuggestion {
pub did: Option<DefId>,
pub descr: &'static str,
pub path: Path,
pub accessible: bool,
pub via_import: bool,
/// An extra note that should be issued if this item is suggested
pub note: Option<String>,
}
/// Adjust the impl span so that just the `impl` keyword is taken by removing
/// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
/// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
///
/// *Attention*: the method used is very fragile since it essentially duplicates the work of the
/// parser. If you need to use this function or something similar, please consider updating the
/// `source_map` functions and this function to something more robust.
fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
let impl_span = sm.span_until_char(impl_span, '<');
sm.span_until_whitespace(impl_span)
}
impl<'a, 'tcx> Resolver<'a, 'tcx> {
pub(crate) fn report_errors(&mut self, krate: &Crate) {
self.report_with_use_injections(krate);
for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
let msg = "macro-expanded `macro_export` macros from the current crate \
cannot be referred to by absolute paths";
self.lint_buffer.buffer_lint_with_diagnostic(
MACRO_EXPANDED_MACRO_EXPORTS_ACCESSED_BY_ABSOLUTE_PATHS,
CRATE_NODE_ID,
span_use,
msg,
BuiltinLintDiagnostics::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def),
);
}
for ambiguity_error in &self.ambiguity_errors {
let diag = self.ambiguity_diagnostics(ambiguity_error);
if ambiguity_error.warning {
let NameBindingKind::Import { import, .. } = ambiguity_error.b1.0.kind else {
unreachable!()
};
self.lint_buffer.buffer_lint_with_diagnostic(
AMBIGUOUS_GLOB_IMPORTS,
import.root_id,
ambiguity_error.ident.span,
diag.msg.to_string(),
BuiltinLintDiagnostics::AmbiguousGlobImports { diag },
);
} else {
let mut err = struct_span_err!(self.tcx.sess, diag.span, E0659, "{}", &diag.msg);
report_ambiguity_error(&mut err, diag);
err.emit();
}
}
let mut reported_spans = FxHashSet::default();
for error in std::mem::take(&mut self.privacy_errors) {
if reported_spans.insert(error.dedup_span) {
self.report_privacy_error(&error);
}
}
}
fn report_with_use_injections(&mut self, krate: &Crate) {
for UseError { mut err, candidates, def_id, instead, suggestion, path, is_call } in
self.use_injections.drain(..)
{
let (span, found_use) = if let Some(def_id) = def_id.as_local() {
UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
} else {
(None, FoundUse::No)
};
if !candidates.is_empty() {
show_candidates(
self.tcx,
&mut err,
span,
&candidates,
if instead { Instead::Yes } else { Instead::No },
found_use,
DiagnosticMode::Normal,
path,
"",
);
err.emit();
} else if let Some((span, msg, sugg, appl)) = suggestion {
err.span_suggestion_verbose(span, msg, sugg, appl);
err.emit();
} else if let [segment] = path.as_slice() && is_call {
err.stash(segment.ident.span, rustc_errors::StashKey::CallIntoMethod);
} else {
err.emit();
}
}
}
pub(crate) fn report_conflict(
&mut self,
parent: Module<'_>,
ident: Ident,
ns: Namespace,
new_binding: NameBinding<'a>,
old_binding: NameBinding<'a>,
) {
// Error on the second of two conflicting names
if old_binding.span.lo() > new_binding.span.lo() {
return self.report_conflict(parent, ident, ns, old_binding, new_binding);
}
let container = match parent.kind {
// Avoid using TyCtxt::def_kind_descr in the resolver, because it
// indirectly *calls* the resolver, and would cause a query cycle.
ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()),
ModuleKind::Block => "block",
};
let old_noun = match old_binding.is_import_user_facing() {
true => "import",
false => "definition",
};
let new_participle = match new_binding.is_import_user_facing() {
true => "imported",
false => "defined",
};
let (name, span) =
(ident.name, self.tcx.sess.source_map().guess_head_span(new_binding.span));
if let Some(s) = self.name_already_seen.get(&name) {
if s == &span {
return;
}
}
let old_kind = match (ns, old_binding.module()) {
(ValueNS, _) => "value",
(MacroNS, _) => "macro",
(TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
(TypeNS, Some(module)) if module.is_normal() => "module",
(TypeNS, Some(module)) if module.is_trait() => "trait",
(TypeNS, _) => "type",
};
let msg = format!("the name `{name}` is defined multiple times");
let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
(true, true) => struct_span_err!(self.tcx.sess, span, E0259, "{}", msg),
(true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
true => struct_span_err!(self.tcx.sess, span, E0254, "{}", msg),
false => struct_span_err!(self.tcx.sess, span, E0260, "{}", msg),
},
_ => match (old_binding.is_import_user_facing(), new_binding.is_import_user_facing()) {
(false, false) => struct_span_err!(self.tcx.sess, span, E0428, "{}", msg),
(true, true) => struct_span_err!(self.tcx.sess, span, E0252, "{}", msg),
_ => struct_span_err!(self.tcx.sess, span, E0255, "{}", msg),
},
};
err.note(format!(
"`{}` must be defined only once in the {} namespace of this {}",
name,
ns.descr(),
container
));
err.span_label(span, format!("`{name}` re{new_participle} here"));
if !old_binding.span.is_dummy() && old_binding.span != span {
err.span_label(
self.tcx.sess.source_map().guess_head_span(old_binding.span),
format!("previous {old_noun} of the {old_kind} `{name}` here"),
);
}
// See https://github.com/rust-lang/rust/issues/32354
use NameBindingKind::Import;
let can_suggest = |binding: NameBinding<'_>, import: self::Import<'_>| {
!binding.span.is_dummy()
&& !matches!(import.kind, ImportKind::MacroUse | ImportKind::MacroExport)
};
let import = match (&new_binding.kind, &old_binding.kind) {
// If there are two imports where one or both have attributes then prefer removing the
// import without attributes.
(Import { import: new, .. }, Import { import: old, .. })
if {
(new.has_attributes || old.has_attributes)
&& can_suggest(old_binding, *old)
&& can_suggest(new_binding, *new)
} =>
{
if old.has_attributes {
Some((*new, new_binding.span, true))
} else {
Some((*old, old_binding.span, true))
}
}
// Otherwise prioritize the new binding.
(Import { import, .. }, other) if can_suggest(new_binding, *import) => {
Some((*import, new_binding.span, other.is_import()))
}
(other, Import { import, .. }) if can_suggest(old_binding, *import) => {
Some((*import, old_binding.span, other.is_import()))
}
_ => None,
};
// Check if the target of the use for both bindings is the same.
let duplicate = new_binding.res().opt_def_id() == old_binding.res().opt_def_id();
let has_dummy_span = new_binding.span.is_dummy() || old_binding.span.is_dummy();
let from_item =
self.extern_prelude.get(&ident).map_or(true, |entry| entry.introduced_by_item);
// Only suggest removing an import if both bindings are to the same def, if both spans
// aren't dummy spans. Further, if both bindings are imports, then the ident must have
// been introduced by an item.
let should_remove_import = duplicate
&& !has_dummy_span
&& ((new_binding.is_extern_crate() || old_binding.is_extern_crate()) || from_item);
match import {
Some((import, span, true)) if should_remove_import && import.is_nested() => {
self.add_suggestion_for_duplicate_nested_use(&mut err, import, span)
}
Some((import, _, true)) if should_remove_import && !import.is_glob() => {
// Simple case - remove the entire import. Due to the above match arm, this can
// only be a single use so just remove it entirely.
err.tool_only_span_suggestion(
import.use_span_with_attributes,
"remove unnecessary import",
"",
Applicability::MaybeIncorrect,
);
}
Some((import, span, _)) => {
self.add_suggestion_for_rename_of_use(&mut err, name, import, span)
}
_ => {}
}
err.emit();
self.name_already_seen.insert(name, span);
}
/// This function adds a suggestion to change the binding name of a new import that conflicts
/// with an existing import.
///
/// ```text,ignore (diagnostic)
/// help: you can use `as` to change the binding name of the import
/// |
/// LL | use foo::bar as other_bar;
/// | ^^^^^^^^^^^^^^^^^^^^^
/// ```
fn add_suggestion_for_rename_of_use(
&self,
err: &mut Diagnostic,
name: Symbol,
import: Import<'_>,
binding_span: Span,
) {
let suggested_name = if name.as_str().chars().next().unwrap().is_uppercase() {
format!("Other{name}")
} else {
format!("other_{name}")
};
let mut suggestion = None;
match import.kind {
ImportKind::Single { type_ns_only: true, .. } => {
suggestion = Some(format!("self as {suggested_name}"))
}
ImportKind::Single { source, .. } => {
if let Some(pos) =
source.span.hi().0.checked_sub(binding_span.lo().0).map(|pos| pos as usize)
{
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(binding_span) {
if pos <= snippet.len() {
suggestion = Some(format!(
"{} as {}{}",
&snippet[..pos],
suggested_name,
if snippet.ends_with(';') { ";" } else { "" }
))
}
}
}
}
ImportKind::ExternCrate { source, target, .. } => {
suggestion = Some(format!(
"extern crate {} as {};",
source.unwrap_or(target.name),
suggested_name,
))
}
_ => unreachable!(),
}
if let Some(suggestion) = suggestion {
err.subdiagnostic(ChangeImportBindingSuggestion { span: binding_span, suggestion });
} else {
err.subdiagnostic(ChangeImportBinding { span: binding_span });
}
}
/// This function adds a suggestion to remove an unnecessary binding from an import that is
/// nested. In the following example, this function will be invoked to remove the `a` binding
/// in the second use statement:
///
/// ```ignore (diagnostic)
/// use issue_52891::a;
/// use issue_52891::{d, a, e};
/// ```
///
/// The following suggestion will be added:
///
/// ```ignore (diagnostic)
/// use issue_52891::{d, a, e};
/// ^-- help: remove unnecessary import
/// ```
///
/// If the nested use contains only one import then the suggestion will remove the entire
/// line.
///
/// It is expected that the provided import is nested - this isn't checked by the
/// function. If this invariant is not upheld, this function's behaviour will be unexpected
/// as characters expected by span manipulations won't be present.
fn add_suggestion_for_duplicate_nested_use(
&self,
err: &mut Diagnostic,
import: Import<'_>,
binding_span: Span,
) {
assert!(import.is_nested());
let message = "remove unnecessary import";
// Two examples will be used to illustrate the span manipulations we're doing:
//
// - Given `use issue_52891::{d, a, e};` where `a` is a duplicate then `binding_span` is
// `a` and `import.use_span` is `issue_52891::{d, a, e};`.
// - Given `use issue_52891::{d, e, a};` where `a` is a duplicate then `binding_span` is
// `a` and `import.use_span` is `issue_52891::{d, e, a};`.
let (found_closing_brace, span) =
find_span_of_binding_until_next_binding(self.tcx.sess, binding_span, import.use_span);
// If there was a closing brace then identify the span to remove any trailing commas from
// previous imports.
if found_closing_brace {
if let Some(span) = extend_span_to_previous_binding(self.tcx.sess, span) {
err.tool_only_span_suggestion(span, message, "", Applicability::MaybeIncorrect);
} else {
// Remove the entire line if we cannot extend the span back, this indicates an
// `issue_52891::{self}` case.
err.span_suggestion(
import.use_span_with_attributes,
message,
"",
Applicability::MaybeIncorrect,
);
}
return;
}
err.span_suggestion(span, message, "", Applicability::MachineApplicable);
}
pub(crate) fn lint_if_path_starts_with_module(
&mut self,
finalize: Option<Finalize>,
path: &[Segment],
second_binding: Option<NameBinding<'_>>,
) {
let Some(Finalize { node_id, root_span, .. }) = finalize else {
return;
};
let first_name = match path.get(0) {
// In the 2018 edition this lint is a hard error, so nothing to do
Some(seg) if seg.ident.span.is_rust_2015() && self.tcx.sess.is_rust_2015() => {
seg.ident.name
}
_ => return,
};
// We're only interested in `use` paths which should start with
// `{{root}}` currently.
if first_name != kw::PathRoot {
return;
}
match path.get(1) {
// If this import looks like `crate::...` it's already good
Some(Segment { ident, .. }) if ident.name == kw::Crate => return,
// Otherwise go below to see if it's an extern crate
Some(_) => {}
// If the path has length one (and it's `PathRoot` most likely)
// then we don't know whether we're gonna be importing a crate or an
// item in our crate. Defer this lint to elsewhere
None => return,
}
// If the first element of our path was actually resolved to an
// `ExternCrate` (also used for `crate::...`) then no need to issue a
// warning, this looks all good!
if let Some(binding) = second_binding {
if let NameBindingKind::Import { import, .. } = binding.kind {
// Careful: we still want to rewrite paths from renamed extern crates.
if let ImportKind::ExternCrate { source: None, .. } = import.kind {
return;
}
}
}
let diag = BuiltinLintDiagnostics::AbsPathWithModule(root_span);
self.lint_buffer.buffer_lint_with_diagnostic(
ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
node_id,
root_span,
"absolute paths must start with `self`, `super`, \
`crate`, or an external crate name in the 2018 edition",
diag,
);
}
pub(crate) fn add_module_candidates(
&mut self,
module: Module<'a>,
names: &mut Vec<TypoSuggestion>,
filter_fn: &impl Fn(Res) -> bool,
ctxt: Option<SyntaxContext>,
) {
for (key, resolution) in self.resolutions(module).borrow().iter() {
if let Some(binding) = resolution.borrow().binding {
let res = binding.res();
if filter_fn(res) && ctxt.map_or(true, |ctxt| ctxt == key.ident.span.ctxt()) {
names.push(TypoSuggestion::typo_from_ident(key.ident, res));
}
}
}
}
/// Combines an error with provided span and emits it.
///
/// This takes the error provided, combines it with the span and any additional spans inside the
/// error and emits it.
pub(crate) fn report_error(&mut self, span: Span, resolution_error: ResolutionError<'a>) {
self.into_struct_error(span, resolution_error).emit();
}
pub(crate) fn into_struct_error(
&mut self,
span: Span,
resolution_error: ResolutionError<'a>,
) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
match resolution_error {
ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
let mut err = struct_span_err!(
self.tcx.sess,
span,
E0401,
"can't use generic parameters from outer function",
);
err.span_label(span, "use of generic parameter from outer function");
let sm = self.tcx.sess.source_map();
let def_id = match outer_res {
Res::SelfTyParam { .. } => {
err.span_label(span, "can't use `Self` here");
return err;
}
Res::SelfTyAlias { alias_to: def_id, .. } => {
err.span_label(
reduce_impl_span_to_impl_keyword(sm, self.def_span(def_id)),
"`Self` type implicitly declared here, by this `impl`",
);
err.span_label(span, "use a type here instead");
return err;
}
Res::Def(DefKind::TyParam, def_id) => {
err.span_label(self.def_span(def_id), "type parameter from outer function");
def_id
}
Res::Def(DefKind::ConstParam, def_id) => {
err.span_label(
self.def_span(def_id),
"const parameter from outer function",
);
def_id
}
_ => {
bug!(
"GenericParamsFromOuterFunction should only be used with \
Res::SelfTyParam, Res::SelfTyAlias, DefKind::TyParam or \
DefKind::ConstParam"
);
}
};
if let HasGenericParams::Yes(span) = has_generic_params {
// Try to retrieve the span of the function signature and generate a new
// message with a local type or const parameter.
let sugg_msg = "try using a local generic parameter instead";
let name = self.tcx.item_name(def_id);
let (span, snippet) = if span.is_empty() {
let snippet = format!("<{name}>");
(span, snippet)
} else {
let span = sm.span_through_char(span, '<').shrink_to_hi();
let snippet = format!("{name}, ");
(span, snippet)
};
// Suggest the modification to the user
err.span_suggestion(span, sugg_msg, snippet, Applicability::MaybeIncorrect);
}
err
}
ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => self
.tcx
.sess
.create_err(errs::NameAlreadyUsedInParameterList { span, first_use_span, name }),
ResolutionError::MethodNotMemberOfTrait(method, trait_, candidate) => {
self.tcx.sess.create_err(errs::MethodNotMemberOfTrait {
span,
method,
trait_,
sub: candidate.map(|c| errs::AssociatedFnWithSimilarNameExists {
span: method.span,
candidate: c,
}),
})
}
ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => {
self.tcx.sess.create_err(errs::TypeNotMemberOfTrait {
span,
type_,
trait_,
sub: candidate.map(|c| errs::AssociatedTypeWithSimilarNameExists {
span: type_.span,
candidate: c,
}),
})
}
ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => {
self.tcx.sess.create_err(errs::ConstNotMemberOfTrait {
span,
const_,
trait_,
sub: candidate.map(|c| errs::AssociatedConstWithSimilarNameExists {
span: const_.span,
candidate: c,
}),
})
}
ResolutionError::VariableNotBoundInPattern(binding_error, parent_scope) => {
let BindingError { name, target, origin, could_be_path } = binding_error;
let target_sp = target.iter().copied().collect::<Vec<_>>();
let origin_sp = origin.iter().copied().collect::<Vec<_>>();
let msp = MultiSpan::from_spans(target_sp.clone());
let mut err = struct_span_err!(
self.tcx.sess,
msp,
E0408,
"variable `{}` is not bound in all patterns",
name,
);
for sp in target_sp {
err.span_label(sp, format!("pattern doesn't bind `{name}`"));
}
for sp in origin_sp {
err.span_label(sp, "variable not in all patterns");
}
if could_be_path {
let import_suggestions = self.lookup_import_candidates(
Ident::with_dummy_span(name),
Namespace::ValueNS,
&parent_scope,
&|res: Res| {
matches!(
res,
Res::Def(
DefKind::Ctor(CtorOf::Variant, CtorKind::Const)
| DefKind::Ctor(CtorOf::Struct, CtorKind::Const)
| DefKind::Const
| DefKind::AssocConst,
_,
)
)
},
);
if import_suggestions.is_empty() {
let help_msg = format!(
"if you meant to match on a variant or a `const` item, consider \
making the path in the pattern qualified: `path::to::ModOrType::{name}`",
);
err.span_help(span, help_msg);
}
show_candidates(
self.tcx,
&mut err,
Some(span),
&import_suggestions,
Instead::No,
FoundUse::Yes,
DiagnosticMode::Pattern,
vec![],
"",
);
}
err
}
ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
self.tcx.sess.create_err(errs::VariableBoundWithDifferentMode {
span,
first_binding_span,
variable_name,
})
}
ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => self
.tcx
.sess
.create_err(errs::IdentifierBoundMoreThanOnceInParameterList { span, identifier }),
ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => self
.tcx
.sess
.create_err(errs::IdentifierBoundMoreThanOnceInSamePattern { span, identifier }),
ResolutionError::UndeclaredLabel { name, suggestion } => {
let ((sub_reachable, sub_reachable_suggestion), sub_unreachable) = match suggestion
{
// A reachable label with a similar name exists.
Some((ident, true)) => (
(
Some(errs::LabelWithSimilarNameReachable(ident.span)),
Some(errs::TryUsingSimilarlyNamedLabel {
span,
ident_name: ident.name,
}),
),
None,
),
// An unreachable label with a similar name exists.
Some((ident, false)) => (
(None, None),
Some(errs::UnreachableLabelWithSimilarNameExists {
ident_span: ident.span,
}),
),
// No similarly-named labels exist.
None => ((None, None), None),
};
self.tcx.sess.create_err(errs::UndeclaredLabel {
span,
name,
sub_reachable,
sub_reachable_suggestion,
sub_unreachable,
})
}
ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
// None of the suggestions below would help with a case like `use self`.
let (suggestion, mpart_suggestion) = if root {
(None, None)
} else {
// use foo::bar::self -> foo::bar
// use foo::bar::self as abc -> foo::bar as abc
let suggestion = errs::SelfImportsOnlyAllowedWithinSuggestion { span };
// use foo::bar::self -> foo::bar::{self}
// use foo::bar::self as abc -> foo::bar::{self as abc}
let mpart_suggestion = errs::SelfImportsOnlyAllowedWithinMultipartSuggestion {
multipart_start: span_with_rename.shrink_to_lo(),
multipart_end: span_with_rename.shrink_to_hi(),
};
(Some(suggestion), Some(mpart_suggestion))
};
self.tcx.sess.create_err(errs::SelfImportsOnlyAllowedWithin {
span,
suggestion,
mpart_suggestion,
})
}
ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
self.tcx.sess.create_err(errs::SelfImportCanOnlyAppearOnceInTheList { span })
}
ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => self
.tcx
.sess
.create_err(errs::SelfImportOnlyInImportListWithNonEmptyPrefix { span }),
ResolutionError::FailedToResolve { last_segment, label, suggestion, module } => {
let mut err =
struct_span_err!(self.tcx.sess, span, E0433, "failed to resolve: {}", &label);
err.span_label(span, label);
if let Some((suggestions, msg, applicability)) = suggestion {
if suggestions.is_empty() {
err.help(msg);
return err;
}
err.multipart_suggestion(msg, suggestions, applicability);
}
if let Some(ModuleOrUniformRoot::Module(module)) = module
&& let Some(module) = module.opt_def_id()
&& let Some(last_segment) = last_segment
{
self.find_cfg_stripped(&mut err, &last_segment, module);
}
err
}
ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
self.tcx.sess.create_err(errs::CannotCaptureDynamicEnvironmentInFnItem { span })
}
ResolutionError::AttemptToUseNonConstantValueInConstant(ident, suggestion, current) => {
// let foo =...
// ^^^ given this Span
// ------- get this Span to have an applicable suggestion
// edit:
// only do this if the const and usage of the non-constant value are on the same line
// the further the two are apart, the higher the chance of the suggestion being wrong
let sp = self
.tcx
.sess
.source_map()
.span_extend_to_prev_str(ident.span, current, true, false);
let ((with, with_label), without) = match sp {
Some(sp) if !self.tcx.sess.source_map().is_multiline(sp) => {
let sp = sp.with_lo(BytePos(sp.lo().0 - (current.len() as u32)));
(
(Some(errs::AttemptToUseNonConstantValueInConstantWithSuggestion {
span: sp,
ident,
suggestion,
current,
}), Some(errs::AttemptToUseNonConstantValueInConstantLabelWithSuggestion {span})),
None,
)
}
_ => (
(None, None),
Some(errs::AttemptToUseNonConstantValueInConstantWithoutSuggestion {
ident_span: ident.span,
suggestion,
}),
),
};
self.tcx.sess.create_err(errs::AttemptToUseNonConstantValueInConstant {
span,
with,
with_label,
without,
})
}
ResolutionError::BindingShadowsSomethingUnacceptable {
shadowing_binding,
name,
participle,
article,
shadowed_binding,
shadowed_binding_span,
} => self.tcx.sess.create_err(errs::BindingShadowsSomethingUnacceptable {
span,
shadowing_binding,
shadowed_binding,
article,
sub_suggestion: match (shadowing_binding, shadowed_binding) {
(
PatternSource::Match,
Res::Def(DefKind::Ctor(CtorOf::Variant | CtorOf::Struct, CtorKind::Fn), _),
) => Some(errs::BindingShadowsSomethingUnacceptableSuggestion { span, name }),
_ => None,
},
shadowed_binding_span,
participle,
name,
}),
ResolutionError::ForwardDeclaredGenericParam => {
self.tcx.sess.create_err(errs::ForwardDeclaredGenericParam { span })
}
ResolutionError::ParamInTyOfConstParam { name, param_kind: is_type } => self
.tcx
.sess
.create_err(errs::ParamInTyOfConstParam { span, name, param_kind: is_type }),
ResolutionError::ParamInNonTrivialAnonConst { name, param_kind: is_type } => {
self.tcx.sess.create_err(errs::ParamInNonTrivialAnonConst {
span,
name,
param_kind: is_type,
help: self
.tcx
.sess
.is_nightly_build()
.then_some(errs::ParamInNonTrivialAnonConstHelp),
})
}
ResolutionError::ParamInEnumDiscriminant { name, param_kind: is_type } => self
.tcx
.sess
.create_err(errs::ParamInEnumDiscriminant { span, name, param_kind: is_type }),
ResolutionError::SelfInGenericParamDefault => {
self.tcx.sess.create_err(errs::SelfInGenericParamDefault { span })
}
ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
let ((sub_suggestion_label, sub_suggestion), sub_unreachable_label) =
match suggestion {
// A reachable label with a similar name exists.
Some((ident, true)) => (
(
Some(errs::UnreachableLabelSubLabel { ident_span: ident.span }),
Some(errs::UnreachableLabelSubSuggestion {
span,
// intentionally taking 'ident.name' instead of 'ident' itself, as this
// could be used in suggestion context
ident_name: ident.name,
}),
),
None,
),
// An unreachable label with a similar name exists.
Some((ident, false)) => (
(None, None),
Some(errs::UnreachableLabelSubLabelUnreachable {
ident_span: ident.span,
}),
),
// No similarly-named labels exist.
None => ((None, None), None),
};
self.tcx.sess.create_err(errs::UnreachableLabel {
span,
name,
definition_span,
sub_suggestion,
sub_suggestion_label,
sub_unreachable_label,
})
}
ResolutionError::TraitImplMismatch {
name,
kind,
code,
trait_item_span,
trait_path,
} => {
let mut err = self.tcx.sess.struct_span_err_with_code(
span,
format!(
"item `{name}` is an associated {kind}, which doesn't match its trait `{trait_path}`",
),
code,
);
err.span_label(span, "does not match trait");
err.span_label(trait_item_span, "item in trait");
err
}
ResolutionError::TraitImplDuplicate { name, trait_item_span, old_span } => self
.tcx
.sess
.create_err(errs::TraitImplDuplicate { span, name, trait_item_span, old_span }),
ResolutionError::InvalidAsmSym => {
self.tcx.sess.create_err(errs::InvalidAsmSym { span })
}
ResolutionError::LowercaseSelf => {
self.tcx.sess.create_err(errs::LowercaseSelf { span })
}
}
}
pub(crate) fn report_vis_error(
&mut self,
vis_resolution_error: VisResolutionError<'_>,
) -> ErrorGuaranteed {
match vis_resolution_error {
VisResolutionError::Relative2018(span, path) => {
self.tcx.sess.create_err(errs::Relative2018 {
span,
path_span: path.span,
// intentionally converting to String, as the text would also be used as
// in suggestion context
path_str: pprust::path_to_string(&path),
})
}
VisResolutionError::AncestorOnly(span) => {
self.tcx.sess.create_err(errs::AncestorOnly(span))
}
VisResolutionError::FailedToResolve(span, label, suggestion) => self.into_struct_error(
span,
ResolutionError::FailedToResolve {
last_segment: None,
label,
suggestion,
module: None,
},
),
VisResolutionError::ExpectedFound(span, path_str, res) => {
self.tcx.sess.create_err(errs::ExpectedFound { span, res, path_str })
}
VisResolutionError::Indeterminate(span) => {
self.tcx.sess.create_err(errs::Indeterminate(span))
}
VisResolutionError::ModuleOnly(span) => {
self.tcx.sess.create_err(errs::ModuleOnly(span))
}
}
.emit()
}
/// Lookup typo candidate in scope for a macro or import.
fn early_lookup_typo_candidate(
&mut self,
scope_set: ScopeSet<'a>,
parent_scope: &ParentScope<'a>,
ident: Ident,
filter_fn: &impl Fn(Res) -> bool,
) -> Option<TypoSuggestion> {
let mut suggestions = Vec::new();
let ctxt = ident.span.ctxt();
self.visit_scopes(scope_set, parent_scope, ctxt, |this, scope, use_prelude, _| {
match scope {
Scope::DeriveHelpers(expn_id) => {
let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
if filter_fn(res) {
suggestions.extend(
this.helper_attrs
.get(&expn_id)
.into_iter()
.flatten()
.map(|ident| TypoSuggestion::typo_from_ident(*ident, res)),
);
}
}
Scope::DeriveHelpersCompat => {
let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
if filter_fn(res) {
for derive in parent_scope.derives {
let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
if let Ok((Some(ext), _)) = this.resolve_macro_path(
derive,
Some(MacroKind::Derive),
parent_scope,
false,
false,
) {
suggestions.extend(
ext.helper_attrs
.iter()
.map(|name| TypoSuggestion::typo_from_name(*name, res)),
);
}
}
}
}
Scope::MacroRules(macro_rules_scope) => {
if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
let res = macro_rules_binding.binding.res();
if filter_fn(res) {
suggestions.push(TypoSuggestion::typo_from_ident(
macro_rules_binding.ident,
res,
))
}
}
}
Scope::CrateRoot => {
let root_ident = Ident::new(kw::PathRoot, ident.span);
let root_module = this.resolve_crate_root(root_ident);
this.add_module_candidates(root_module, &mut suggestions, filter_fn, None);
}
Scope::Module(module, _) => {
this.add_module_candidates(module, &mut suggestions, filter_fn, None);
}
Scope::MacroUsePrelude => {
suggestions.extend(this.macro_use_prelude.iter().filter_map(
|(name, binding)| {
let res = binding.res();
filter_fn(res).then_some(TypoSuggestion::typo_from_name(*name, res))
},
));
}
Scope::BuiltinAttrs => {
let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin(kw::Empty));
if filter_fn(res) {
suggestions.extend(
BUILTIN_ATTRIBUTES
.iter()
.map(|attr| TypoSuggestion::typo_from_name(attr.name, res)),
);
}
}
Scope::ExternPrelude => {
suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id());
filter_fn(res).then_some(TypoSuggestion::typo_from_ident(*ident, res))
}));
}
Scope::ToolPrelude => {
let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
suggestions.extend(
this.registered_tools
.iter()
.map(|ident| TypoSuggestion::typo_from_ident(*ident, res)),
);
}
Scope::StdLibPrelude => {
if let Some(prelude) = this.prelude {
let mut tmp_suggestions = Vec::new();
this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn, None);
suggestions.extend(
tmp_suggestions
.into_iter()
.filter(|s| use_prelude || this.is_builtin_macro(s.res)),
);
}
}
Scope::BuiltinTypes => {
suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| {
let res = Res::PrimTy(*prim_ty);
filter_fn(res)
.then_some(TypoSuggestion::typo_from_name(prim_ty.name(), res))
}))
}
}
None::<()>
});
// Make sure error reporting is deterministic.
suggestions.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap());
match find_best_match_for_name(
&suggestions.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
ident.name,
None,
) {
Some(found) if found != ident.name => {
suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
}
_ => None,
}
}
fn lookup_import_candidates_from_module<FilterFn>(
&mut self,
lookup_ident: Ident,
namespace: Namespace,
parent_scope: &ParentScope<'a>,
start_module: Module<'a>,
crate_name: Ident,
filter_fn: FilterFn,
) -> Vec<ImportSuggestion>
where
FilterFn: Fn(Res) -> bool,
{
let mut candidates = Vec::new();
let mut seen_modules = FxHashSet::default();
let mut worklist = vec![(start_module, ThinVec::<ast::PathSegment>::new(), true)];
let mut worklist_via_import = vec![];
while let Some((in_module, path_segments, accessible)) = match worklist.pop() {
None => worklist_via_import.pop(),
Some(x) => Some(x),
} {
let in_module_is_extern = !in_module.def_id().is_local();
// We have to visit module children in deterministic order to avoid
// instabilities in reported imports (#43552).
in_module.for_each_child(self, |this, ident, ns, name_binding| {
// avoid non-importable candidates
if !name_binding.is_importable() {
return;
}
let child_accessible =
accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
// do not venture inside inaccessible items of other crates
if in_module_is_extern && !child_accessible {
return;
}
let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
// There is an assumption elsewhere that paths of variants are in the enum's
// declaration and not imported. With this assumption, the variant component is
// chopped and the rest of the path is assumed to be the enum's own path. For
// errors where a variant is used as the type instead of the enum, this causes
// funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
if via_import && name_binding.is_possibly_imported_variant() {
return;
}
// #90113: Do not count an inaccessible reexported item as a candidate.
if let NameBindingKind::Import { binding, .. } = name_binding.kind {
if this.is_accessible_from(binding.vis, parent_scope.module)
&& !this.is_accessible_from(name_binding.vis, parent_scope.module)
{
return;
}
}
// collect results based on the filter function
// avoid suggesting anything from the same module in which we are resolving
// avoid suggesting anything with a hygienic name
if ident.name == lookup_ident.name
&& ns == namespace
&& in_module != parent_scope.module
&& !ident.span.normalize_to_macros_2_0().from_expansion()
{
let res = name_binding.res();
if filter_fn(res) {
// create the path
let mut segms = path_segments.clone();
if lookup_ident.span.at_least_rust_2018() {
// crate-local absolute paths start with `crate::` in edition 2018
// FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
segms.insert(0, ast::PathSegment::from_ident(crate_name));
}
segms.push(ast::PathSegment::from_ident(ident));
let path = Path { span: name_binding.span, segments: segms, tokens: None };
let did = match res {
Res::Def(DefKind::Ctor(..), did) => this.tcx.opt_parent(did),
_ => res.opt_def_id(),
};
if child_accessible {
// Remove invisible match if exists
if let Some(idx) = candidates
.iter()
.position(|v: &ImportSuggestion| v.did == did && !v.accessible)
{
candidates.remove(idx);
}
}
if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
// See if we're recommending TryFrom, TryInto, or FromIterator and add
// a note about editions
let note = if let Some(did) = did {
let requires_note = !did.is_local()
&& this.tcx.get_attrs(did, sym::rustc_diagnostic_item).any(
|attr| {
[sym::TryInto, sym::TryFrom, sym::FromIterator]
.map(|x| Some(x))
.contains(&attr.value_str())
},
);
requires_note.then(|| {
format!(
"'{}' is included in the prelude starting in Edition 2021",
path_names_to_string(&path)
)
})
} else {
None
};
candidates.push(ImportSuggestion {
did,
descr: res.descr(),
path,
accessible: child_accessible,
note,
via_import,
});
}
}
}
// collect submodules to explore
if let Some(module) = name_binding.module() {
// form the path
let mut path_segments = path_segments.clone();
path_segments.push(ast::PathSegment::from_ident(ident));
let is_extern_crate_that_also_appears_in_prelude =
name_binding.is_extern_crate() && lookup_ident.span.at_least_rust_2018();
if !is_extern_crate_that_also_appears_in_prelude {
// add the module to the lookup
if seen_modules.insert(module.def_id()) {
if via_import { &mut worklist_via_import } else { &mut worklist }
.push((module, path_segments, child_accessible));
}
}
}
})
}
// If only some candidates are accessible, take just them
if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
candidates.retain(|x| x.accessible)
}
candidates
}
/// When name resolution fails, this method can be used to look up candidate
/// entities with the expected name. It allows filtering them using the
/// supplied predicate (which should be used to only accept the types of
/// definitions expected, e.g., traits). The lookup spans across all crates.
///
/// N.B., the method does not look into imports, but this is not a problem,
/// since we report the definitions (thus, the de-aliased imports).
pub(crate) fn lookup_import_candidates<FilterFn>(
&mut self,
lookup_ident: Ident,
namespace: Namespace,
parent_scope: &ParentScope<'a>,
filter_fn: FilterFn,
) -> Vec<ImportSuggestion>
where
FilterFn: Fn(Res) -> bool,
{
let mut suggestions = self.lookup_import_candidates_from_module(
lookup_ident,
namespace,
parent_scope,
self.graph_root,
Ident::with_dummy_span(kw::Crate),
&filter_fn,
);
if lookup_ident.span.at_least_rust_2018() {
let extern_prelude_names = self.extern_prelude.clone();
for (ident, _) in extern_prelude_names.into_iter() {
if ident.span.from_expansion() {
// Idents are adjusted to the root context before being
// resolved in the extern prelude, so reporting this to the
// user is no help. This skips the injected
// `extern crate std` in the 2018 edition, which would
// otherwise cause duplicate suggestions.
continue;
}
let crate_id = self.crate_loader(|c| c.maybe_process_path_extern(ident.name));
if let Some(crate_id) = crate_id {
let crate_root = self.expect_module(crate_id.as_def_id());
suggestions.extend(self.lookup_import_candidates_from_module(
lookup_ident,
namespace,
parent_scope,
crate_root,
ident,
&filter_fn,
));
}
}
}
suggestions
}
pub(crate) fn unresolved_macro_suggestions(
&mut self,
err: &mut Diagnostic,
macro_kind: MacroKind,
parent_scope: &ParentScope<'a>,
ident: Ident,
krate: &Crate,
) {
let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
let suggestion = self.early_lookup_typo_candidate(
ScopeSet::Macro(macro_kind),
parent_scope,
ident,
is_expected,
);
self.add_typo_suggestion(err, suggestion, ident.span);
let import_suggestions =
self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected);
let (span, found_use) = match parent_scope.module.nearest_parent_mod().as_local() {
Some(def_id) => UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id]),
None => (None, FoundUse::No),
};
show_candidates(
self.tcx,
err,
span,
&import_suggestions,
Instead::No,
found_use,
DiagnosticMode::Normal,
vec![],
"",
);
if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
err.subdiagnostic(ExplicitUnsafeTraits { span: ident.span, ident });
return;
}
if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
err.subdiagnostic(AddedMacroUse);
return;
}
if ident.name == kw::Default
&& let ModuleKind::Def(DefKind::Enum, def_id, _) = parent_scope.module.kind
{
let span = self.def_span(def_id);
let source_map = self.tcx.sess.source_map();
let head_span = source_map.guess_head_span(span);
err.subdiagnostic(ConsiderAddingADerive {
span: head_span.shrink_to_lo(),
suggestion: "#[derive(Default)]\n".to_string(),
});
}
for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
if let Ok(binding) = self.early_resolve_ident_in_lexical_scope(
ident,
ScopeSet::All(ns),
&parent_scope,
None,
false,
None,
) {
let desc = match binding.res() {
Res::Def(DefKind::Macro(MacroKind::Bang), _) => {
"a function-like macro".to_string()
}
Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => {
format!("an attribute: `#[{ident}]`")
}
Res::Def(DefKind::Macro(MacroKind::Derive), _) => {
format!("a derive macro: `#[derive({ident})]`")
}
Res::ToolMod => {
// Don't confuse the user with tool modules.
continue;
}
Res::Def(DefKind::Trait, _) if macro_kind == MacroKind::Derive => {
"only a trait, without a derive macro".to_string()
}
res => format!(
"{} {}, not {} {}",
res.article(),
res.descr(),
macro_kind.article(),
macro_kind.descr_expected(),
),
};
if let crate::NameBindingKind::Import { import, .. } = binding.kind {
if !import.span.is_dummy() {
err.span_note(
import.span,
format!("`{ident}` is imported here, but it is {desc}"),
);
// Silence the 'unused import' warning we might get,
// since this diagnostic already covers that import.
self.record_use(ident, binding, false);
return;
}
}
err.note(format!("`{ident}` is in scope, but it is {desc}"));
return;
}
}
}
pub(crate) fn add_typo_suggestion(
&self,
err: &mut Diagnostic,
suggestion: Option<TypoSuggestion>,
span: Span,
) -> bool {
let suggestion = match suggestion {
None => return false,
// We shouldn't suggest underscore.
Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
Some(suggestion) => suggestion,
};
if let Some(def_span) = suggestion.res.opt_def_id().map(|def_id| self.def_span(def_id)) {
if span.overlaps(def_span) {
// Don't suggest typo suggestion for itself like in the following:
// error[E0423]: expected function, tuple struct or tuple variant, found struct `X`
// --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14
// |
// LL | struct X {}
// | ----------- `X` defined here
// LL |
// LL | const Y: X = X("ö");
// | -------------^^^^^^- similarly named constant `Y` defined here
// |
// help: use struct literal syntax instead
// |
// LL | const Y: X = X {};
// | ^^^^
// help: a constant with a similar name exists
// |
// LL | const Y: X = Y("ö");
// | ^
return false;
}
let prefix = match suggestion.target {
SuggestionTarget::SimilarlyNamed => "similarly named ",
SuggestionTarget::SingleItem => "",
};
err.span_label(
self.tcx.sess.source_map().guess_head_span(def_span),
format!(
"{}{} `{}` defined here",
prefix,
suggestion.res.descr(),
suggestion.candidate,
),
);
}
let msg = match suggestion.target {
SuggestionTarget::SimilarlyNamed => format!(
"{} {} with a similar name exists",
suggestion.res.article(),
suggestion.res.descr()
),
SuggestionTarget::SingleItem => {
format!("maybe you meant this {}", suggestion.res.descr())
}
};
err.span_suggestion(span, msg, suggestion.candidate, Applicability::MaybeIncorrect);
true
}
fn binding_description(&self, b: NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
let res = b.res();
if b.span.is_dummy() || !self.tcx.sess.source_map().is_span_accessible(b.span) {
// These already contain the "built-in" prefix or look bad with it.
let add_built_in =
!matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);
let (built_in, from) = if from_prelude {
("", " from prelude")
} else if b.is_extern_crate()
&& !b.is_import()
&& self.tcx.sess.opts.externs.get(ident.as_str()).is_some()
{
("", " passed with `--extern`")
} else if add_built_in {
(" built-in", "")
} else {
("", "")
};
let a = if built_in.is_empty() { res.article() } else { "a" };
format!("{a}{built_in} {thing}{from}", thing = res.descr())
} else {
let introduced = if b.is_import_user_facing() { "imported" } else { "defined" };
format!("the {thing} {introduced} here", thing = res.descr())
}
}
fn ambiguity_diagnostics(&self, ambiguity_error: &AmbiguityError<'_>) -> AmbiguityErrorDiag {
let AmbiguityError { kind, ident, b1, b2, misc1, misc2, .. } = *ambiguity_error;
let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
// We have to print the span-less alternative first, otherwise formatting looks bad.
(b2, b1, misc2, misc1, true)
} else {
(b1, b2, misc1, misc2, false)
};
let could_refer_to = |b: NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
let note_msg = format!("`{ident}` could{also} refer to {what}");
let thing = b.res().descr();
let mut help_msgs = Vec::new();
if b.is_glob_import()
&& (kind == AmbiguityKind::GlobVsGlob
|| kind == AmbiguityKind::GlobVsExpanded
|| kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
{
help_msgs.push(format!(
"consider adding an explicit import of `{ident}` to disambiguate"
))
}
if b.is_extern_crate() && ident.span.at_least_rust_2018() {
help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
}
match misc {
AmbiguityErrorMisc::SuggestCrate => help_msgs
.push(format!("use `crate::{ident}` to refer to this {thing} unambiguously")),
AmbiguityErrorMisc::SuggestSelf => help_msgs
.push(format!("use `self::{ident}` to refer to this {thing} unambiguously")),
AmbiguityErrorMisc::FromPrelude | AmbiguityErrorMisc::None => {}
}
(
b.span,
note_msg,
help_msgs
.iter()
.enumerate()
.map(|(i, help_msg)| {
let or = if i == 0 { "" } else { "or " };
format!("{or}{help_msg}")
})
.collect::<Vec<_>>(),
)
};
let (b1_span, b1_note_msg, b1_help_msgs) = could_refer_to(b1, misc1, "");
let (b2_span, b2_note_msg, b2_help_msgs) = could_refer_to(b2, misc2, " also");
AmbiguityErrorDiag {
msg: format!("`{ident}` is ambiguous"),
span: ident.span,
label_span: ident.span,
label_msg: "ambiguous name".to_string(),
note_msg: format!("ambiguous because of {}", kind.descr()),
b1_span,
b1_note_msg,
b1_help_msgs,
b2_span,
b2_note_msg,
b2_help_msgs,
}
}
/// If the binding refers to a tuple struct constructor with fields,
/// returns the span of its fields.
fn ctor_fields_span(&self, binding: NameBinding<'_>) -> Option<Span> {
if let NameBindingKind::Res(Res::Def(
DefKind::Ctor(CtorOf::Struct, CtorKind::Fn),
ctor_def_id,
)) = binding.kind
{
let def_id = self.tcx.parent(ctor_def_id);
return self
.field_def_ids(def_id)?
.iter()
.map(|&field_id| self.def_span(field_id))
.reduce(Span::to); // None for `struct Foo()`
}
None
}
fn report_privacy_error(&mut self, privacy_error: &PrivacyError<'a>) {
let PrivacyError { ident, binding, outermost_res, parent_scope, dedup_span } =
*privacy_error;
let res = binding.res();
let ctor_fields_span = self.ctor_fields_span(binding);
let plain_descr = res.descr().to_string();
let nonimport_descr =
if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
let import_descr = nonimport_descr.clone() + " import";
let get_descr =
|b: NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
// Print the primary message.
let descr = get_descr(binding);
let mut err =
struct_span_err!(self.tcx.sess, ident.span, E0603, "{} `{}` is private", descr, ident);
err.span_label(ident.span, format!("private {descr}"));
if let Some((this_res, outer_ident)) = outermost_res {
let import_suggestions = self.lookup_import_candidates(
outer_ident,
this_res.ns().unwrap_or(Namespace::TypeNS),
&parent_scope,
&|res: Res| res == this_res,
);
let point_to_def = !show_candidates(
self.tcx,
&mut err,
Some(dedup_span.until(outer_ident.span.shrink_to_hi())),
&import_suggestions,
Instead::Yes,
FoundUse::Yes,
DiagnosticMode::Import,
vec![],
"",
);
// If we suggest importing a public re-export, don't point at the definition.
if point_to_def && ident.span != outer_ident.span {
err.span_label(
outer_ident.span,
format!("{} `{outer_ident}` is not publicly re-exported", this_res.descr()),
);
}
}
let mut non_exhaustive = None;
// If an ADT is foreign and marked as `non_exhaustive`, then that's
// probably why we have the privacy error.
// Otherwise, point out if the struct has any private fields.
if let Some(def_id) = res.opt_def_id()
&& !def_id.is_local()
&& let Some(attr) = self.tcx.get_attr(def_id, sym::non_exhaustive)
{
non_exhaustive = Some(attr.span);
} else if let Some(span) = ctor_fields_span {
err.span_label(span, "a constructor is private if any of the fields is private");
if let Res::Def(_, d) = res && let Some(fields) = self.field_visibility_spans.get(&d) {
err.multipart_suggestion_verbose(
format!(
"consider making the field{} publicly accessible",
pluralize!(fields.len())
),
fields.iter().map(|span| (*span, "pub ".to_string())).collect(),
Applicability::MaybeIncorrect,
);
}
}
// Print the whole import chain to make it easier to see what happens.
let first_binding = binding;
let mut next_binding = Some(binding);
let mut next_ident = ident;
while let Some(binding) = next_binding {
let name = next_ident;
next_binding = match binding.kind {
_ if res == Res::Err => None,
NameBindingKind::Import { binding, import, .. } => match import.kind {
_ if binding.span.is_dummy() => None,
ImportKind::Single { source, .. } => {
next_ident = source;
Some(binding)
}
ImportKind::Glob { .. } | ImportKind::MacroUse | ImportKind::MacroExport => {
Some(binding)
}
ImportKind::ExternCrate { .. } => None,
},
_ => None,
};
let first = binding == first_binding;
let msg = format!(
"{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
and_refers_to = if first { "" } else { "...and refers to " },
item = get_descr(binding),
which = if first { "" } else { " which" },
dots = if next_binding.is_some() { "..." } else { "" },
);
let def_span = self.tcx.sess.source_map().guess_head_span(binding.span);
let mut note_span = MultiSpan::from_span(def_span);
if !first && binding.vis.is_public() {
note_span.push_span_label(def_span, "consider importing it directly");
}
// Final step in the import chain, point out if the ADT is `non_exhaustive`
// which is probably why this privacy violation occurred.
if next_binding.is_none() && let Some(span) = non_exhaustive {
note_span.push_span_label(
span,
"cannot be constructed because it is `#[non_exhaustive]`",
);
}
err.span_note(note_span, msg);
}
err.emit();
}
pub(crate) fn find_similarly_named_module_or_crate(
&mut self,
ident: Symbol,
current_module: Module<'a>,
) -> Option<Symbol> {
let mut candidates = self
.extern_prelude
.keys()
.map(|ident| ident.name)
.chain(
self.module_map
.iter()
.filter(|(_, module)| {
current_module.is_ancestor_of(**module) && current_module != **module
})
.flat_map(|(_, module)| module.kind.name()),
)
.filter(|c| !c.to_string().is_empty())
.collect::<Vec<_>>();
candidates.sort();
candidates.dedup();
match find_best_match_for_name(&candidates, ident, None) {
Some(sugg) if sugg == ident => None,
sugg => sugg,
}
}
pub(crate) fn report_path_resolution_error(
&mut self,
path: &[Segment],
opt_ns: Option<Namespace>, // `None` indicates a module path in import
parent_scope: &ParentScope<'a>,
ribs: Option<&PerNS<Vec<Rib<'a>>>>,
ignore_binding: Option<NameBinding<'a>>,
module: Option<ModuleOrUniformRoot<'a>>,
failed_segment_idx: usize,
ident: Ident,
) -> (String, Option<Suggestion>) {
let is_last = failed_segment_idx == path.len() - 1;
let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
let module_res = match module {
Some(ModuleOrUniformRoot::Module(module)) => module.res(),
_ => None,
};
if module_res == self.graph_root.res() {
let is_mod = |res| matches!(res, Res::Def(DefKind::Mod, _));
let mut candidates = self.lookup_import_candidates(ident, TypeNS, parent_scope, is_mod);
candidates
.sort_by_cached_key(|c| (c.path.segments.len(), pprust::path_to_string(&c.path)));
if let Some(candidate) = candidates.get(0) {
(
String::from("unresolved import"),
Some((
vec![(ident.span, pprust::path_to_string(&candidate.path))],
String::from("a similar path exists"),
Applicability::MaybeIncorrect,
)),
)
} else if self.tcx.sess.is_rust_2015() {
(
format!("maybe a missing crate `{ident}`?"),
Some((
vec![],
format!(
"consider adding `extern crate {ident}` to use the `{ident}` crate"
),
Applicability::MaybeIncorrect,
)),
)
} else {
(format!("could not find `{ident}` in the crate root"), None)
}
} else if failed_segment_idx > 0 {
let parent = path[failed_segment_idx - 1].ident.name;
let parent = match parent {
// ::foo is mounted at the crate root for 2015, and is the extern
// prelude for 2018+
kw::PathRoot if self.tcx.sess.edition() > Edition::Edition2015 => {
"the list of imported crates".to_owned()
}
kw::PathRoot | kw::Crate => "the crate root".to_owned(),
_ => format!("`{parent}`"),
};
let mut msg = format!("could not find `{ident}` in {parent}");
if ns == TypeNS || ns == ValueNS {
let ns_to_try = if ns == TypeNS { ValueNS } else { TypeNS };
let binding = if let Some(module) = module {
self.resolve_ident_in_module(
module,
ident,
ns_to_try,
parent_scope,
None,
ignore_binding,
).ok()
} else if let Some(ribs) = ribs
&& let Some(TypeNS | ValueNS) = opt_ns
{
match self.resolve_ident_in_lexical_scope(
ident,
ns_to_try,
parent_scope,
None,
&ribs[ns_to_try],
ignore_binding,
) {
// we found a locally-imported or available item/module
Some(LexicalScopeBinding::Item(binding)) => Some(binding),
_ => None,
}
} else {
self.early_resolve_ident_in_lexical_scope(
ident,
ScopeSet::All(ns_to_try),
parent_scope,
None,
false,
ignore_binding,
).ok()
};
if let Some(binding) = binding {
let mut found = |what| {
msg = format!(
"expected {}, found {} `{}` in {}",
ns.descr(),
what,
ident,
parent
)
};
if binding.module().is_some() {
found("module")
} else {
match binding.res() {
// Avoid using TyCtxt::def_kind_descr in the resolver, because it
// indirectly *calls* the resolver, and would cause a query cycle.
Res::Def(kind, id) => found(kind.descr(id)),
_ => found(ns_to_try.descr()),
}
}
};
}
(msg, None)
} else if ident.name == kw::SelfUpper {
// As mentioned above, `opt_ns` being `None` indicates a module path in import.
// We can use this to improve a confusing error for, e.g. `use Self::Variant` in an
// impl
if opt_ns.is_none() {
("`Self` cannot be used in imports".to_string(), None)
} else {
(
"`Self` is only available in impls, traits, and type definitions".to_string(),
None,
)
}
} else if ident.name.as_str().chars().next().is_some_and(|c| c.is_ascii_uppercase()) {
// Check whether the name refers to an item in the value namespace.
let binding = if let Some(ribs) = ribs {
self.resolve_ident_in_lexical_scope(
ident,
ValueNS,
parent_scope,
None,
&ribs[ValueNS],
ignore_binding,
)
} else {
None
};
let match_span = match binding {
// Name matches a local variable. For example:
// ```
// fn f() {
// let Foo: &str = "";
// println!("{}", Foo::Bar); // Name refers to local
// // variable `Foo`.
// }
// ```
Some(LexicalScopeBinding::Res(Res::Local(id))) => {
Some(*self.pat_span_map.get(&id).unwrap())
}
// Name matches item from a local name binding
// created by `use` declaration. For example:
// ```
// pub Foo: &str = "";
//
// mod submod {
// use super::Foo;
// println!("{}", Foo::Bar); // Name refers to local
// // binding `Foo`.
// }
// ```
Some(LexicalScopeBinding::Item(name_binding)) => Some(name_binding.span),
_ => None,
};
let suggestion = match_span.map(|span| {
(
vec![(span, String::from(""))],
format!("`{ident}` is defined here, but is not a type"),
Applicability::MaybeIncorrect,
)
});
(format!("use of undeclared type `{ident}`"), suggestion)
} else {
let mut suggestion = None;
if ident.name == sym::alloc {
suggestion = Some((
vec![],
String::from("add `extern crate alloc` to use the `alloc` crate"),
Applicability::MaybeIncorrect,
))
}
suggestion = suggestion.or_else(|| {
self.find_similarly_named_module_or_crate(ident.name, parent_scope.module).map(
|sugg| {
(
vec![(ident.span, sugg.to_string())],
String::from("there is a crate or module with a similar name"),
Applicability::MaybeIncorrect,
)
},
)
});
(format!("use of undeclared crate or module `{ident}`"), suggestion)
}
}
/// Adds suggestions for a path that cannot be resolved.
pub(crate) fn make_path_suggestion(
&mut self,
span: Span,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'a>,
) -> Option<(Vec<Segment>, Option<String>)> {
debug!("make_path_suggestion: span={:?} path={:?}", span, path);
match (path.get(0), path.get(1)) {
// `{{root}}::ident::...` on both editions.
// On 2015 `{{root}}` is usually added implicitly.
(Some(fst), Some(snd))
if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
// `ident::...` on 2018.
(Some(fst), _)
if fst.ident.span.at_least_rust_2018() && !fst.ident.is_path_segment_keyword() =>
{
// Insert a placeholder that's later replaced by `self`/`super`/etc.
path.insert(0, Segment::from_ident(Ident::empty()));
}
_ => return None,
}
self.make_missing_self_suggestion(path.clone(), parent_scope)
.or_else(|| self.make_missing_crate_suggestion(path.clone(), parent_scope))
.or_else(|| self.make_missing_super_suggestion(path.clone(), parent_scope))
.or_else(|| self.make_external_crate_suggestion(path, parent_scope))
}
/// Suggest a missing `self::` if that resolves to an correct module.
///
/// ```text
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `self::foo`?
/// ```
fn make_missing_self_suggestion(
&mut self,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'a>,
) -> Option<(Vec<Segment>, Option<String>)> {
// Replace first ident with `self` and check if that is valid.
path[0].ident.name = kw::SelfLower;
let result = self.maybe_resolve_path(&path, None, parent_scope);
debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result { Some((path, None)) } else { None }
}
/// Suggests a missing `crate::` if that resolves to an correct module.
///
/// ```text
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `crate::foo`?
/// ```
fn make_missing_crate_suggestion(
&mut self,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'a>,
) -> Option<(Vec<Segment>, Option<String>)> {
// Replace first ident with `crate` and check if that is valid.
path[0].ident.name = kw::Crate;
let result = self.maybe_resolve_path(&path, None, parent_scope);
debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some((
path,
Some(
"`use` statements changed in Rust 2018; read more at \
<https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
clarity.html>"
.to_string(),
),
))
} else {
None
}
}
/// Suggests a missing `super::` if that resolves to an correct module.
///
/// ```text
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `super::foo`?
/// ```
fn make_missing_super_suggestion(
&mut self,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'a>,
) -> Option<(Vec<Segment>, Option<String>)> {
// Replace first ident with `crate` and check if that is valid.
path[0].ident.name = kw::Super;
let result = self.maybe_resolve_path(&path, None, parent_scope);
debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result { Some((path, None)) } else { None }
}
/// Suggests a missing external crate name if that resolves to an correct module.
///
/// ```text
/// |
/// LL | use foobar::Baz;
/// | ^^^^^^ did you mean `baz::foobar`?
/// ```
///
/// Used when importing a submodule of an external crate but missing that crate's
/// name as the first part of path.
fn make_external_crate_suggestion(
&mut self,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'a>,
) -> Option<(Vec<Segment>, Option<String>)> {
if path[1].ident.span.is_rust_2015() {
return None;
}
// Sort extern crate names in *reverse* order to get
// 1) some consistent ordering for emitted diagnostics, and
// 2) `std` suggestions before `core` suggestions.
let mut extern_crate_names =
self.extern_prelude.keys().map(|ident| ident.name).collect::<Vec<_>>();
extern_crate_names.sort_by(|a, b| b.as_str().partial_cmp(a.as_str()).unwrap());
for name in extern_crate_names.into_iter() {
// Replace first ident with a crate name and check if that is valid.
path[0].ident.name = name;
let result = self.maybe_resolve_path(&path, None, parent_scope);
debug!(
"make_external_crate_suggestion: name={:?} path={:?} result={:?}",
name, path, result
);
if let PathResult::Module(..) = result {
return Some((path, None));
}
}
None
}
/// Suggests importing a macro from the root of the crate rather than a module within
/// the crate.
///
/// ```text
/// help: a macro with this name exists at the root of the crate
/// |
/// LL | use issue_59764::makro;
/// | ^^^^^^^^^^^^^^^^^^
/// |
/// = note: this could be because a macro annotated with `#[macro_export]` will be exported
/// at the root of the crate instead of the module where it is defined
/// ```
pub(crate) fn check_for_module_export_macro(
&mut self,
import: Import<'a>,
module: ModuleOrUniformRoot<'a>,
ident: Ident,
) -> Option<(Option<Suggestion>, Option<String>)> {
let ModuleOrUniformRoot::Module(mut crate_module) = module else {
return None;
};
while let Some(parent) = crate_module.parent {
crate_module = parent;
}
if module == ModuleOrUniformRoot::Module(crate_module) {
// Don't make a suggestion if the import was already from the root of the crate.
return None;
}
let resolutions = self.resolutions(crate_module).borrow();
let binding_key = BindingKey::new(ident, MacroNS);
let resolution = resolutions.get(&binding_key)?;
let binding = resolution.borrow().binding()?;
if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
let module_name = crate_module.kind.name().unwrap();
let import_snippet = match import.kind {
ImportKind::Single { source, target, .. } if source != target => {
format!("{source} as {target}")
}
_ => format!("{ident}"),
};
let mut corrections: Vec<(Span, String)> = Vec::new();
if !import.is_nested() {
// Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
// intermediate segments.
corrections.push((import.span, format!("{module_name}::{import_snippet}")));
} else {
// Find the binding span (and any trailing commas and spaces).
// ie. `use a::b::{c, d, e};`
// ^^^
let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
self.tcx.sess,
import.span,
import.use_span,
);
debug!(
"check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
found_closing_brace, binding_span
);
let mut removal_span = binding_span;
if found_closing_brace {
// If the binding span ended with a closing brace, as in the below example:
// ie. `use a::b::{c, d};`
// ^
// Then expand the span of characters to remove to include the previous
// binding's trailing comma.
// ie. `use a::b::{c, d};`
// ^^^
if let Some(previous_span) =
extend_span_to_previous_binding(self.tcx.sess, binding_span)
{
debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
removal_span = removal_span.with_lo(previous_span.lo());
}
}
debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
// Remove the `removal_span`.
corrections.push((removal_span, "".to_string()));
// Find the span after the crate name and if it has nested imports immediately
// after the crate name already.
// ie. `use a::b::{c, d};`
// ^^^^^^^^^
// or `use a::{b, c, d}};`
// ^^^^^^^^^^^
let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
self.tcx.sess,
module_name,
import.use_span,
);
debug!(
"check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
has_nested, after_crate_name
);
let source_map = self.tcx.sess.source_map();
// Make sure this is actually crate-relative.
let is_definitely_crate = import
.module_path
.first()
.is_some_and(|f| f.ident.name != kw::SelfLower && f.ident.name != kw::Super);
// Add the import to the start, with a `{` if required.
let start_point = source_map.start_point(after_crate_name);
if is_definitely_crate && let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
corrections.push((
start_point,
if has_nested {
// In this case, `start_snippet` must equal '{'.
format!("{start_snippet}{import_snippet}, ")
} else {
// In this case, add a `{`, then the moved import, then whatever
// was there before.
format!("{{{import_snippet}, {start_snippet}")
},
));
// Add a `};` to the end if nested, matching the `{` added at the start.
if !has_nested {
corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
}
} else {
// If the root import is module-relative, add the import separately
corrections.push((
import.use_span.shrink_to_lo(),
format!("use {module_name}::{import_snippet};\n"),
));
}
}
let suggestion = Some((
corrections,
String::from("a macro with this name exists at the root of the crate"),
Applicability::MaybeIncorrect,
));
Some((suggestion, Some("this could be because a macro annotated with `#[macro_export]` will be exported \
at the root of the crate instead of the module where it is defined"
.to_string())))
} else {
None
}
}
/// Finds a cfg-ed out item inside `module` with the matching name.
pub(crate) fn find_cfg_stripped(
&mut self,
err: &mut Diagnostic,
last_segment: &Symbol,
module: DefId,
) {
let local_items;
let symbols = if module.is_local() {
local_items = self
.stripped_cfg_items
.iter()
.filter_map(|item| {
let parent_module = self.opt_local_def_id(item.parent_module)?.to_def_id();
Some(StrippedCfgItem { parent_module, name: item.name, cfg: item.cfg.clone() })
})
.collect::<Vec<_>>();
local_items.as_slice()
} else {
self.tcx.stripped_cfg_items(module.krate)
};
for &StrippedCfgItem { parent_module, name, ref cfg } in symbols {
if parent_module != module || name.name != *last_segment {
continue;
}
err.span_note(name.span, "found an item that was configured out");
if let MetaItemKind::List(nested) = &cfg.kind
&& let NestedMetaItem::MetaItem(meta_item) = &nested[0]
&& let MetaItemKind::NameValue(feature_name) = &meta_item.kind
{
err.note(format!("the item is gated behind the `{}` feature", feature_name.symbol));
}
}
}
}
/// Given a `binding_span` of a binding within a use statement:
///
/// ```ignore (illustrative)
/// use foo::{a, b, c};
/// // ^
/// ```
///
/// then return the span until the next binding or the end of the statement:
///
/// ```ignore (illustrative)
/// use foo::{a, b, c};
/// // ^^^
/// ```
fn find_span_of_binding_until_next_binding(
sess: &Session,
binding_span: Span,
use_span: Span,
) -> (bool, Span) {
let source_map = sess.source_map();
// Find the span of everything after the binding.
// ie. `a, e};` or `a};`
let binding_until_end = binding_span.with_hi(use_span.hi());
// Find everything after the binding but not including the binding.
// ie. `, e};` or `};`
let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
// Keep characters in the span until we encounter something that isn't a comma or
// whitespace.
// ie. `, ` or ``.
//
// Also note whether a closing brace character was encountered. If there
// was, then later go backwards to remove any trailing commas that are left.
let mut found_closing_brace = false;
let after_binding_until_next_binding =
source_map.span_take_while(after_binding_until_end, |&ch| {
if ch == '}' {
found_closing_brace = true;
}
ch == ' ' || ch == ','
});
// Combine the two spans.
// ie. `a, ` or `a`.
//
// Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
let span = binding_span.with_hi(after_binding_until_next_binding.hi());
(found_closing_brace, span)
}
/// Given a `binding_span`, return the span through to the comma or opening brace of the previous
/// binding.
///
/// ```ignore (illustrative)
/// use foo::a::{a, b, c};
/// // ^^--- binding span
/// // |
/// // returned span
///
/// use foo::{a, b, c};
/// // --- binding span
/// ```
fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
let source_map = sess.source_map();
// `prev_source` will contain all of the source that came before the span.
// Then split based on a command and take the first (ie. closest to our span)
// snippet. In the example, this is a space.
let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
return None;
}
let prev_comma = prev_comma.first().unwrap();
let prev_starting_brace = prev_starting_brace.first().unwrap();
// If the amount of source code before the comma is greater than
// the amount of source code before the starting brace then we've only
// got one item in the nested item (eg. `issue_52891::{self}`).
if prev_comma.len() > prev_starting_brace.len() {
return None;
}
Some(binding_span.with_lo(BytePos(
// Take away the number of bytes for the characters we've found and an
// extra for the comma.
binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
)))
}
/// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
/// it is a nested use tree.
///
/// ```ignore (illustrative)
/// use foo::a::{b, c};
/// // ^^^^^^^^^^ -- false
///
/// use foo::{a, b, c};
/// // ^^^^^^^^^^ -- true
///
/// use foo::{a, b::{c, d}};
/// // ^^^^^^^^^^^^^^^ -- true
/// ```
fn find_span_immediately_after_crate_name(
sess: &Session,
module_name: Symbol,
use_span: Span,
) -> (bool, Span) {
debug!(
"find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
module_name, use_span
);
let source_map = sess.source_map();
// Using `use issue_59764::foo::{baz, makro};` as an example throughout..
let mut num_colons = 0;
// Find second colon.. `use issue_59764:`
let until_second_colon = source_map.span_take_while(use_span, |c| {
if *c == ':' {
num_colons += 1;
}
!matches!(c, ':' if num_colons == 2)
});
// Find everything after the second colon.. `foo::{baz, makro};`
let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
let mut found_a_non_whitespace_character = false;
// Find the first non-whitespace character in `from_second_colon`.. `f`
let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
if found_a_non_whitespace_character {
return false;
}
if !c.is_whitespace() {
found_a_non_whitespace_character = true;
}
true
});
// Find the first `{` in from_second_colon.. `foo::{`
let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
(next_left_bracket == after_second_colon, from_second_colon)
}
/// A suggestion has already been emitted, change the wording slightly to clarify that both are
/// independent options.
enum Instead {
Yes,
No,
}
/// Whether an existing place with an `use` item was found.
enum FoundUse {
Yes,
No,
}
/// Whether a binding is part of a pattern or a use statement. Used for diagnostics.
pub(crate) enum DiagnosticMode {
Normal,
/// The binding is part of a pattern
Pattern,
/// The binding is part of a use statement
Import,
}
pub(crate) fn import_candidates(
tcx: TyCtxt<'_>,
err: &mut Diagnostic,
// This is `None` if all placement locations are inside expansions
use_placement_span: Option<Span>,
candidates: &[ImportSuggestion],
mode: DiagnosticMode,
append: &str,
) {
show_candidates(
tcx,
err,
use_placement_span,
candidates,
Instead::Yes,
FoundUse::Yes,
mode,
vec![],
append,
);
}
/// When an entity with a given name is not available in scope, we search for
/// entities with that name in all crates. This method allows outputting the
/// results of this search in a programmer-friendly way. If any entities are
/// found and suggested, returns `true`, otherwise returns `false`.
fn show_candidates(
tcx: TyCtxt<'_>,
err: &mut Diagnostic,
// This is `None` if all placement locations are inside expansions
use_placement_span: Option<Span>,
candidates: &[ImportSuggestion],
instead: Instead,
found_use: FoundUse,
mode: DiagnosticMode,
path: Vec<Segment>,
append: &str,
) -> bool {
if candidates.is_empty() {
return false;
}
let mut accessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>, bool)> =
Vec::new();
let mut inaccessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>, bool)> =
Vec::new();
candidates.iter().for_each(|c| {
(if c.accessible { &mut accessible_path_strings } else { &mut inaccessible_path_strings })
.push((path_names_to_string(&c.path), c.descr, c.did, &c.note, c.via_import))
});
// we want consistent results across executions, but candidates are produced
// by iterating through a hash map, so make sure they are ordered:
for path_strings in [&mut accessible_path_strings, &mut inaccessible_path_strings] {
path_strings.sort_by(|a, b| a.0.cmp(&b.0));
let core_path_strings =
path_strings.extract_if(|p| p.0.starts_with("core::")).collect::<Vec<_>>();
path_strings.extend(core_path_strings);
path_strings.dedup_by(|a, b| a.0 == b.0);
}
if !accessible_path_strings.is_empty() {
let (determiner, kind, name, through) =
if let [(name, descr, _, _, via_import)] = &accessible_path_strings[..] {
(
"this",
*descr,
format!(" `{name}`"),
if *via_import { " through its public re-export" } else { "" },
)
} else {
("one of these", "items", String::new(), "")
};
let instead = if let Instead::Yes = instead { " instead" } else { "" };
let mut msg = if let DiagnosticMode::Pattern = mode {
format!(
"if you meant to match on {kind}{instead}{name}, use the full path in the pattern",
)
} else {
format!("consider importing {determiner} {kind}{through}{instead}")
};
for note in accessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
err.note(note.clone());
}
if let Some(span) = use_placement_span {
let (add_use, trailing) = match mode {
DiagnosticMode::Pattern => {
err.span_suggestions(
span,
msg,
accessible_path_strings.into_iter().map(|a| a.0),
Applicability::MaybeIncorrect,
);
return true;
}
DiagnosticMode::Import => ("", ""),
DiagnosticMode::Normal => ("use ", ";\n"),
};
for candidate in &mut accessible_path_strings {
// produce an additional newline to separate the new use statement
// from the directly following item.
let additional_newline = if let FoundUse::No = found_use && let DiagnosticMode::Normal = mode { "\n" } else { "" };
candidate.0 =
format!("{add_use}{}{append}{trailing}{additional_newline}", &candidate.0);
}
err.span_suggestions_with_style(
span,
msg,
accessible_path_strings.into_iter().map(|a| a.0),
Applicability::MaybeIncorrect,
SuggestionStyle::ShowAlways,
);
if let [first, .., last] = &path[..] {
let sp = first.ident.span.until(last.ident.span);
if sp.can_be_used_for_suggestions() {
err.span_suggestion_verbose(
sp,
format!("if you import `{}`, refer to it directly", last.ident),
"",
Applicability::Unspecified,
);
}
}
} else {
msg.push(':');
for candidate in accessible_path_strings {
msg.push('\n');
msg.push_str(&candidate.0);
}
err.help(msg);
}
true
} else if !matches!(mode, DiagnosticMode::Import) {
assert!(!inaccessible_path_strings.is_empty());
let prefix = if let DiagnosticMode::Pattern = mode {
"you might have meant to match on "
} else {
""
};
if let [(name, descr, def_id, note, _)] = &inaccessible_path_strings[..] {
let msg = format!(
"{prefix}{descr} `{name}`{} exists but is inaccessible",
if let DiagnosticMode::Pattern = mode { ", which" } else { "" }
);
if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
let span = tcx.source_span(local_def_id);
let span = tcx.sess.source_map().guess_head_span(span);
let mut multi_span = MultiSpan::from_span(span);
multi_span.push_span_label(span, "not accessible");
err.span_note(multi_span, msg);
} else {
err.note(msg);
}
if let Some(note) = (*note).as_deref() {
err.note(note.to_string());
}
} else {
let (_, descr_first, _, _, _) = &inaccessible_path_strings[0];
let descr = if inaccessible_path_strings
.iter()
.skip(1)
.all(|(_, descr, _, _, _)| descr == descr_first)
{
descr_first
} else {
"item"
};
let plural_descr =
if descr.ends_with('s') { format!("{descr}es") } else { format!("{descr}s") };
let mut msg = format!("{prefix}these {plural_descr} exist but are inaccessible");
let mut has_colon = false;
let mut spans = Vec::new();
for (name, _, def_id, _, _) in &inaccessible_path_strings {
if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
let span = tcx.source_span(local_def_id);
let span = tcx.sess.source_map().guess_head_span(span);
spans.push((name, span));
} else {
if !has_colon {
msg.push(':');
has_colon = true;
}
msg.push('\n');
msg.push_str(name);
}
}
let mut multi_span = MultiSpan::from_spans(spans.iter().map(|(_, sp)| *sp).collect());
for (name, span) in spans {
multi_span.push_span_label(span, format!("`{name}`: not accessible"));
}
for note in inaccessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
err.note(note.clone());
}
err.span_note(multi_span, msg);
}
true
} else {
false
}
}
#[derive(Debug)]
struct UsePlacementFinder {
target_module: NodeId,
first_legal_span: Option<Span>,
first_use_span: Option<Span>,
}
impl UsePlacementFinder {
fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, FoundUse) {
let mut finder =
UsePlacementFinder { target_module, first_legal_span: None, first_use_span: None };
finder.visit_crate(krate);
if let Some(use_span) = finder.first_use_span {
(Some(use_span), FoundUse::Yes)
} else {
(finder.first_legal_span, FoundUse::No)
}
}
}
impl<'tcx> visit::Visitor<'tcx> for UsePlacementFinder {
fn visit_crate(&mut self, c: &Crate) {
if self.target_module == CRATE_NODE_ID {
let inject = c.spans.inject_use_span;
if is_span_suitable_for_use_injection(inject) {
self.first_legal_span = Some(inject);
}
self.first_use_span = search_for_any_use_in_items(&c.items);
return;
} else {
visit::walk_crate(self, c);
}
}
fn visit_item(&mut self, item: &'tcx ast::Item) {
if self.target_module == item.id {
if let ItemKind::Mod(_, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind {
let inject = mod_spans.inject_use_span;
if is_span_suitable_for_use_injection(inject) {
self.first_legal_span = Some(inject);
}
self.first_use_span = search_for_any_use_in_items(items);
return;
}
} else {
visit::walk_item(self, item);
}
}
}
fn search_for_any_use_in_items(items: &[P<ast::Item>]) -> Option<Span> {
for item in items {
if let ItemKind::Use(..) = item.kind {
if is_span_suitable_for_use_injection(item.span) {
return Some(item.span.shrink_to_lo());
}
}
}
return None;
}
fn is_span_suitable_for_use_injection(s: Span) -> bool {
// don't suggest placing a use before the prelude
// import or other generated ones
!s.from_expansion()
}
/// Convert the given number into the corresponding ordinal
pub(crate) fn ordinalize(v: usize) -> String {
let suffix = match ((11..=13).contains(&(v % 100)), v % 10) {
(false, 1) => "st",
(false, 2) => "nd",
(false, 3) => "rd",
_ => "th",
};
format!("{v}{suffix}")
}
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