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use std::cmp::Reverse;
use errors::{Applicability, DiagnosticBuilder, DiagnosticId};
use log::debug;
use rustc::bug;
use rustc::hir::def::{self, DefKind, NonMacroAttrKind};
use rustc::hir::def::Namespace::{self, *};
use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
use rustc::session::Session;
use rustc::ty::{self, DefIdTree};
use rustc::util::nodemap::FxHashSet;
use syntax::ast::{self, Ident, Path};
use syntax::ext::base::MacroKind;
use syntax::feature_gate::BUILTIN_ATTRIBUTES;
use syntax::source_map::SourceMap;
use syntax::struct_span_err;
use syntax::symbol::{Symbol, kw};
use syntax::util::lev_distance::find_best_match_for_name;
use syntax_pos::{BytePos, Span, MultiSpan};
use crate::resolve_imports::{ImportDirective, ImportDirectiveSubclass, ImportResolver};
use crate::{path_names_to_string, KNOWN_TOOLS};
use crate::{BindingError, CrateLint, HasGenericParams, LegacyScope, Module, ModuleOrUniformRoot};
use crate::{PathResult, ParentScope, ResolutionError, Resolver, Scope, ScopeSet, Segment};
type Res = def::Res<ast::NodeId>;
/// A vector of spans and replacements, a message and applicability.
crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
crate struct TypoSuggestion {
pub candidate: Symbol,
pub res: Res,
}
impl TypoSuggestion {
crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
TypoSuggestion { candidate, res }
}
}
/// A free importable items suggested in case of resolution failure.
crate struct ImportSuggestion {
pub did: Option<DefId>,
pub path: Path,
}
/// 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(cm: &SourceMap, impl_span: Span) -> Span {
let impl_span = cm.span_until_char(impl_span, '<');
let impl_span = cm.span_until_whitespace(impl_span);
impl_span
}
crate fn add_typo_suggestion(
err: &mut DiagnosticBuilder<'_>, suggestion: Option<TypoSuggestion>, span: Span
) -> bool {
if let Some(suggestion) = suggestion {
let msg = format!(
"{} {} with a similar name exists", suggestion.res.article(), suggestion.res.descr()
);
err.span_suggestion(
span, &msg, suggestion.candidate.to_string(), Applicability::MaybeIncorrect
);
return true;
}
false
}
impl<'a> Resolver<'a> {
crate fn add_module_candidates(
&mut self,
module: Module<'a>,
names: &mut Vec<TypoSuggestion>,
filter_fn: &impl Fn(Res) -> bool,
) {
for (&(ident, _), resolution) in self.resolutions(module).borrow().iter() {
if let Some(binding) = resolution.borrow().binding {
let res = binding.res();
if filter_fn(res) {
names.push(TypoSuggestion::from_res(ident.name, 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.
crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
self.into_struct_error(span, resolution_error).emit();
}
crate fn into_struct_error(
&self, span: Span, resolution_error: ResolutionError<'_>
) -> DiagnosticBuilder<'_> {
match resolution_error {
ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
let mut err = struct_span_err!(self.session,
span,
E0401,
"can't use generic parameters from outer function",
);
err.span_label(span, format!("use of generic parameter from outer function"));
let cm = self.session.source_map();
match outer_res {
Res::SelfTy(maybe_trait_defid, maybe_impl_defid) => {
if let Some(impl_span) = maybe_impl_defid.and_then(|def_id| {
self.definitions.opt_span(def_id)
}) {
err.span_label(
reduce_impl_span_to_impl_keyword(cm, impl_span),
"`Self` type implicitly declared here, by this `impl`",
);
}
match (maybe_trait_defid, maybe_impl_defid) {
(Some(_), None) => {
err.span_label(span, "can't use `Self` here");
}
(_, Some(_)) => {
err.span_label(span, "use a type here instead");
}
(None, None) => bug!("`impl` without trait nor type?"),
}
return err;
},
Res::Def(DefKind::TyParam, def_id) => {
if let Some(span) = self.definitions.opt_span(def_id) {
err.span_label(span, "type parameter from outer function");
}
}
Res::Def(DefKind::ConstParam, def_id) => {
if let Some(span) = self.definitions.opt_span(def_id) {
err.span_label(span, "const parameter from outer function");
}
}
_ => {
bug!("GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
DefKind::TyParam");
}
}
if has_generic_params == HasGenericParams::Yes {
// Try to retrieve the span of the function signature and generate a new
// message with a local type or const parameter.
let sugg_msg = &format!("try using a local generic parameter instead");
if let Some((sugg_span, snippet)) = cm.generate_local_type_param_snippet(span) {
// Suggest the modification to the user
err.span_suggestion(
sugg_span,
sugg_msg,
snippet,
Applicability::MachineApplicable,
);
} else if let Some(sp) = cm.generate_fn_name_span(span) {
err.span_label(sp,
format!("try adding a local generic parameter in this method instead"));
} else {
err.help(&format!("try using a local generic parameter instead"));
}
}
err
}
ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
let mut err = struct_span_err!(
self.session,
span,
E0403,
"the name `{}` is already used for a generic \
parameter in this item's generic parameters",
name,
);
err.span_label(span, "already used");
err.span_label(first_use_span, format!("first use of `{}`", name));
err
}
ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
let mut err = struct_span_err!(self.session,
span,
E0407,
"method `{}` is not a member of trait `{}`",
method,
trait_);
err.span_label(span, format!("not a member of trait `{}`", trait_));
err
}
ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
let mut err = struct_span_err!(self.session,
span,
E0437,
"type `{}` is not a member of trait `{}`",
type_,
trait_);
err.span_label(span, format!("not a member of trait `{}`", trait_));
err
}
ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
let mut err = struct_span_err!(self.session,
span,
E0438,
"const `{}` is not a member of trait `{}`",
const_,
trait_);
err.span_label(span, format!("not a member of trait `{}`", trait_));
err
}
ResolutionError::VariableNotBoundInPattern(binding_error) => {
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 msg = format!("variable `{}` is not bound in all patterns", name);
let mut err = self.session.struct_span_err_with_code(
msp,
&msg,
DiagnosticId::Error("E0408".into()),
);
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 help_msg = format!(
"if you meant to match on a variant or a `const` item, consider \
making the path in the pattern qualified: `?::{}`",
name,
);
err.span_help(span, &help_msg);
}
err
}
ResolutionError::VariableBoundWithDifferentMode(variable_name,
first_binding_span) => {
let mut err = struct_span_err!(self.session,
span,
E0409,
"variable `{}` is bound in inconsistent \
ways within the same match arm",
variable_name);
err.span_label(span, "bound in different ways");
err.span_label(first_binding_span, "first binding");
err
}
ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
let mut err = struct_span_err!(self.session,
span,
E0415,
"identifier `{}` is bound more than once in this parameter list",
identifier);
err.span_label(span, "used as parameter more than once");
err
}
ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
let mut err = struct_span_err!(self.session,
span,
E0416,
"identifier `{}` is bound more than once in the same pattern",
identifier);
err.span_label(span, "used in a pattern more than once");
err
}
ResolutionError::UndeclaredLabel(name, lev_candidate) => {
let mut err = struct_span_err!(self.session,
span,
E0426,
"use of undeclared label `{}`",
name);
if let Some(lev_candidate) = lev_candidate {
err.span_suggestion(
span,
"a label with a similar name exists in this scope",
lev_candidate.to_string(),
Applicability::MaybeIncorrect,
);
} else {
err.span_label(span, format!("undeclared label `{}`", name));
}
err
}
ResolutionError::SelfImportsOnlyAllowedWithin => {
struct_span_err!(self.session,
span,
E0429,
"{}",
"`self` imports are only allowed within a { } list")
}
ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
let mut err = struct_span_err!(self.session, span, E0430,
"`self` import can only appear once in an import list");
err.span_label(span, "can only appear once in an import list");
err
}
ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
let mut err = struct_span_err!(self.session, span, E0431,
"`self` import can only appear in an import list with \
a non-empty prefix");
err.span_label(span, "can only appear in an import list with a non-empty prefix");
err
}
ResolutionError::FailedToResolve { label, suggestion } => {
let mut err = struct_span_err!(self.session, span, E0433,
"failed to resolve: {}", &label);
err.span_label(span, label);
if let Some((suggestions, msg, applicability)) = suggestion {
err.multipart_suggestion(&msg, suggestions, applicability);
}
err
}
ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
let mut err = struct_span_err!(self.session,
span,
E0434,
"{}",
"can't capture dynamic environment in a fn item");
err.help("use the `|| { ... }` closure form instead");
err
}
ResolutionError::AttemptToUseNonConstantValueInConstant => {
let mut err = struct_span_err!(self.session, span, E0435,
"attempt to use a non-constant value in a constant");
err.span_label(span, "non-constant value");
err
}
ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
let res = binding.res();
let shadows_what = res.descr();
let mut err = struct_span_err!(self.session, span, E0530, "{}s cannot shadow {}s",
what_binding, shadows_what);
err.span_label(span, format!("cannot be named the same as {} {}",
res.article(), shadows_what));
let participle = if binding.is_import() { "imported" } else { "defined" };
let msg = format!("the {} `{}` is {} here", shadows_what, name, participle);
err.span_label(binding.span, msg);
err
}
ResolutionError::ForwardDeclaredTyParam => {
let mut err = struct_span_err!(self.session, span, E0128,
"type parameters with a default cannot use \
forward declared identifiers");
err.span_label(
span, "defaulted type parameters cannot be forward declared".to_string());
err
}
ResolutionError::SelfInTyParamDefault => {
let mut err = struct_span_err!(
self.session,
span,
E0735,
"type parameters cannot use `Self` in their defaults"
);
err.span_label(
span, "`Self` in type parameter default".to_string());
err
}
ResolutionError::ConstParamDependentOnTypeParam => {
let mut err = struct_span_err!(
self.session,
span,
E0671,
"const parameters cannot depend on type parameters"
);
err.span_label(span, format!("const parameter depends on type parameter"));
err
}
}
}
/// Lookup typo candidate in scope for a macro or import.
fn early_lookup_typo_candidate(
&mut self,
scope_set: ScopeSet,
parent_scope: &ParentScope<'a>,
ident: Ident,
filter_fn: &impl Fn(Res) -> bool,
) -> Option<TypoSuggestion> {
let mut suggestions = Vec::new();
self.visit_scopes(scope_set, parent_scope, ident, |this, scope, use_prelude, _| {
match scope {
Scope::DeriveHelpers => {
let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
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::from_res(*name, res)
}));
}
}
}
}
Scope::MacroRules(legacy_scope) => {
if let LegacyScope::Binding(legacy_binding) = legacy_scope {
let res = legacy_binding.binding.res();
if filter_fn(res) {
suggestions.push(
TypoSuggestion::from_res(legacy_binding.ident.name, 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);
}
Scope::Module(module) => {
this.add_module_candidates(module, &mut suggestions, filter_fn);
}
Scope::MacroUsePrelude => {
suggestions.extend(this.macro_use_prelude.iter().filter_map(|(name, binding)| {
let res = binding.res();
if filter_fn(res) {
Some(TypoSuggestion::from_res(*name, res))
} else {
None
}
}));
}
Scope::BuiltinAttrs => {
let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin);
if filter_fn(res) {
suggestions.extend(BUILTIN_ATTRIBUTES.iter().map(|(name, ..)| {
TypoSuggestion::from_res(*name, res)
}));
}
}
Scope::LegacyPluginHelpers => {
let res = Res::NonMacroAttr(NonMacroAttrKind::LegacyPluginHelper);
if filter_fn(res) {
let plugin_attributes = this.session.plugin_attributes.borrow();
suggestions.extend(plugin_attributes.iter().map(|(name, _)| {
TypoSuggestion::from_res(*name, res)
}));
}
}
Scope::ExternPrelude => {
suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
if filter_fn(res) {
Some(TypoSuggestion::from_res(ident.name, res))
} else {
None
}
}));
}
Scope::ToolPrelude => {
let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
suggestions.extend(KNOWN_TOOLS.iter().map(|name| {
TypoSuggestion::from_res(*name, 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);
suggestions.extend(tmp_suggestions.into_iter().filter(|s| {
use_prelude || this.is_builtin_macro(s.res)
}));
}
}
Scope::BuiltinTypes => {
let primitive_types = &this.primitive_type_table.primitive_types;
suggestions.extend(
primitive_types.iter().flat_map(|(name, prim_ty)| {
let res = Res::PrimTy(*prim_ty);
if filter_fn(res) {
Some(TypoSuggestion::from_res(*name, res))
} else {
None
}
})
)
}
}
None::<()>
});
// Make sure error reporting is deterministic.
suggestions.sort_by_cached_key(|suggestion| suggestion.candidate.as_str());
match find_best_match_for_name(
suggestions.iter().map(|suggestion| &suggestion.candidate),
&ident.as_str(),
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,
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 not_local_module = crate_name.name != kw::Crate;
let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), not_local_module)];
while let Some((in_module,
path_segments,
in_module_is_extern)) = worklist.pop() {
// 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 imports entirely
if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
// avoid non-importable candidates as well
if !name_binding.is_importable() { return; }
// collect results based on the filter function
if ident.name == lookup_ident.name && ns == namespace {
let res = name_binding.res();
if filter_fn(res) {
// create the path
let mut segms = path_segments.clone();
if lookup_ident.span.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,
};
// the entity is accessible in the following cases:
// 1. if it's defined in the same crate, it's always
// accessible (since private entities can be made public)
// 2. if it's defined in another crate, it's accessible
// only if both the module is public and the entity is
// declared as public (due to pruning, we don't explore
// outside crate private modules => no need to check this)
if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
let did = match res {
Res::Def(DefKind::Ctor(..), did) => this.parent(did),
_ => res.opt_def_id(),
};
candidates.push(ImportSuggestion { did, path });
}
}
}
// 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.rust_2018();
let is_visible_to_user =
!in_module_is_extern || name_binding.vis == ty::Visibility::Public;
if !is_extern_crate_that_also_appears_in_prelude && is_visible_to_user {
// add the module to the lookup
let is_extern = in_module_is_extern || name_binding.is_extern_crate();
if seen_modules.insert(module.def_id().unwrap()) {
worklist.push((module, path_segments, is_extern));
}
}
}
})
}
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).
crate fn lookup_import_candidates<FilterFn>(
&mut self, lookup_ident: Ident, namespace: Namespace, filter_fn: FilterFn
) -> Vec<ImportSuggestion>
where FilterFn: Fn(Res) -> bool
{
let mut suggestions = self.lookup_import_candidates_from_module(
lookup_ident, namespace, self.graph_root, Ident::with_dummy_span(kw::Crate), &filter_fn
);
if lookup_ident.span.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;
}
if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name,
ident.span) {
let crate_root = self.get_module(DefId {
krate: crate_id,
index: CRATE_DEF_INDEX,
});
suggestions.extend(self.lookup_import_candidates_from_module(
lookup_ident, namespace, crate_root, ident, &filter_fn));
}
}
}
suggestions
}
crate fn unresolved_macro_suggestions(
&mut self,
err: &mut DiagnosticBuilder<'a>,
macro_kind: MacroKind,
parent_scope: &ParentScope<'a>,
ident: Ident,
) {
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
);
add_typo_suggestion(err, suggestion, ident.span);
if macro_kind == MacroKind::Derive &&
(ident.as_str() == "Send" || ident.as_str() == "Sync") {
let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
err.span_note(ident.span, &msg);
}
if self.macro_names.contains(&ident.modern()) {
err.help("have you added the `#[macro_use]` on the module/import?");
}
}
}
impl<'a, 'b> ImportResolver<'a, 'b> {
/// 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<'b>,
) -> Option<(Vec<Segment>, Vec<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.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::invalid()));
}
_ => return None,
}
self.make_missing_self_suggestion(span, path.clone(), parent_scope)
.or_else(|| self.make_missing_crate_suggestion(span, path.clone(), parent_scope))
.or_else(|| self.make_missing_super_suggestion(span, path.clone(), parent_scope))
.or_else(|| self.make_external_crate_suggestion(span, path, parent_scope))
}
/// Suggest a missing `self::` if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `self::foo`?
/// ```
fn make_missing_self_suggestion(
&mut self,
span: Span,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'b>,
) -> Option<(Vec<Segment>, Vec<String>)> {
// Replace first ident with `self` and check if that is valid.
path[0].ident.name = kw::SelfLower;
let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some((path, Vec::new()))
} else {
None
}
}
/// Suggests a missing `crate::` if that resolves to an correct module.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `crate::foo`?
/// ```
fn make_missing_crate_suggestion(
&mut self,
span: Span,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'b>,
) -> Option<(Vec<Segment>, Vec<String>)> {
// Replace first ident with `crate` and check if that is valid.
path[0].ident.name = kw::Crate;
let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
debug!("make_missing_crate_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some((
path,
vec![
"`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.
///
/// ```
/// |
/// LL | use foo::Bar;
/// | ^^^ did you mean `super::foo`?
/// ```
fn make_missing_super_suggestion(
&mut self,
span: Span,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'b>,
) -> Option<(Vec<Segment>, Vec<String>)> {
// Replace first ident with `crate` and check if that is valid.
path[0].ident.name = kw::Super;
let result = self.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
debug!("make_missing_super_suggestion: path={:?} result={:?}", path, result);
if let PathResult::Module(..) = result {
Some((path, Vec::new()))
} else {
None
}
}
/// Suggests a missing external crate name if that resolves to an correct module.
///
/// ```
/// |
/// 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,
span: Span,
mut path: Vec<Segment>,
parent_scope: &ParentScope<'b>,
) -> Option<(Vec<Segment>, Vec<String>)> {
if path[1].ident.span.rust_2015() {
return None;
}
// Sort extern crate names in reverse order to get
// 1) some consistent ordering for emitted dignostics, and
// 2) `std` suggestions before `core` suggestions.
let mut extern_crate_names =
self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
extern_crate_names.sort_by_key(|name| Reverse(name.as_str()));
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.r.resolve_path(&path, None, parent_scope, false, span, CrateLint::No);
debug!("make_external_crate_suggestion: name={:?} path={:?} result={:?}",
name, path, result);
if let PathResult::Module(..) = result {
return Some((path, Vec::new()));
}
}
None
}
/// Suggests importing a macro from the root of the crate rather than a module within
/// the crate.
///
/// ```
/// 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,
directive: &'b ImportDirective<'b>,
module: ModuleOrUniformRoot<'b>,
ident: Ident,
) -> Option<(Option<Suggestion>, Vec<String>)> {
let mut crate_module = if let ModuleOrUniformRoot::Module(module) = module {
module
} else {
return None;
};
while let Some(parent) = crate_module.parent {
crate_module = parent;
}
if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
// Don't make a suggestion if the import was already from the root of the
// crate.
return None;
}
let resolutions = self.r.resolutions(crate_module).borrow();
let resolution = resolutions.get(&(ident, MacroNS))?;
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 = match directive.subclass {
ImportDirectiveSubclass::SingleImport { source, target, .. } if source != target =>
format!("{} as {}", source, target),
_ => format!("{}", ident),
};
let mut corrections: Vec<(Span, String)> = Vec::new();
if !directive.is_nested() {
// Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
// intermediate segments.
corrections.push((directive.span, format!("{}::{}", module_name, import)));
} 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.r.session, directive.span, directive.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.r.session, 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 immediatately
// 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.r.session, module_name, directive.use_span,
);
debug!("check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
has_nested, after_crate_name);
let source_map = self.r.session.source_map();
// Add the import to the start, with a `{` if required.
let start_point = source_map.start_point(after_crate_name);
if 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)
} else {
// In this case, add a `{`, then the moved import, then whatever
// was there before.
format!("{{{}, {}", import, 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()));
}
}
let suggestion = Some((
corrections,
String::from("a macro with this name exists at the root of the crate"),
Applicability::MaybeIncorrect,
));
let note = vec![
"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(),
];
Some((suggestion, note))
} else {
None
}
}
}
/// Given a `binding_span` of a binding within a use statement:
///
/// ```
/// use foo::{a, b, c};
/// ^
/// ```
///
/// then return the span until the next binding or the end of the statement:
///
/// ```
/// use foo::{a, b, c};
/// ^^^
/// ```
pub(crate) 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.
///
/// ```
/// use foo::a::{a, b, c};
/// ^^--- binding span
/// |
/// returned span
///
/// use foo::{a, b, c};
/// --- binding span
/// ```
pub(crate) 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.
///
/// ```
/// 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; }
match c {
':' if num_colons == 2 => false,
_ => true,
}
});
// 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)
}
/// 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
crate fn show_candidates(
err: &mut DiagnosticBuilder<'_>,
// This is `None` if all placement locations are inside expansions
span: Option<Span>,
candidates: &[ImportSuggestion],
better: bool,
found_use: bool,
) {
// we want consistent results across executions, but candidates are produced
// by iterating through a hash map, so make sure they are ordered:
let mut path_strings: Vec<_> =
candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
path_strings.sort();
let better = if better { "better " } else { "" };
let msg_diff = match path_strings.len() {
1 => " is found in another module, you can import it",
_ => "s are found in other modules, you can import them",
};
let msg = format!("possible {}candidate{} into scope", better, msg_diff);
if let Some(span) = span {
for candidate in &mut path_strings {
// produce an additional newline to separate the new use statement
// from the directly following item.
let additional_newline = if found_use {
""
} else {
"\n"
};
*candidate = format!("use {};\n{}", candidate, additional_newline);
}
err.span_suggestions(
span,
&msg,
path_strings.into_iter(),
Applicability::Unspecified,
);
} else {
let mut msg = msg;
msg.push(':');
for candidate in path_strings {
msg.push('\n');
msg.push_str(&candidate);
}
}
}