compiler/rustc_resolve/src/diagnostics.rs

   1 use std::ptr;
   2
   3 use rustc_ast::{self as ast, Path};
   4 use rustc_ast_pretty::pprust;
   5 use rustc_data_structures::fx::FxHashSet;
   6 use rustc_errors::{
   7     struct_span_err, Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan,
   8 };
   9 use rustc_feature::BUILTIN_ATTRIBUTES;
  10 use rustc_hir::def::Namespace::{self, *};
  11 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
  12 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
  13 use rustc_hir::PrimTy;
  14 use rustc_middle::bug;
  15 use rustc_middle::ty::DefIdTree;
  16 use rustc_session::Session;
  17 use rustc_span::hygiene::MacroKind;
  18 use rustc_span::lev_distance::find_best_match_for_name;
  19 use rustc_span::source_map::SourceMap;
  20 use rustc_span::symbol::{kw, sym, Ident, Symbol};
  21 use rustc_span::{BytePos, Span};
  22 use tracing::debug;
  23
  24 use crate::imports::{Import, ImportKind, ImportResolver};
  25 use crate::path_names_to_string;
  26 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind};
  27 use crate::{BindingError, HasGenericParams, MacroRulesScope, Module, ModuleOrUniformRoot};
  28 use crate::{Finalize, NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
  29 use crate::{ParentScope, PathResult, ResolutionError, Resolver, Scope, ScopeSet, Segment};
  30
  31 type Res = def::Res<ast::NodeId>;
  32
  33 /// A vector of spans and replacements, a message and applicability.
  34 crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
  35
  36 /// Potential candidate for an undeclared or out-of-scope label - contains the ident of a
  37 /// similarly named label and whether or not it is reachable.
  38 crate type LabelSuggestion = (Ident, bool);
  39
  40 crate enum SuggestionTarget {
  41     /// The target has a similar name as the name used by the programmer (probably a typo)
  42     SimilarlyNamed,
  43     /// The target is the only valid item that can be used in the corresponding context
  44     SingleItem,
  45 }
  46
  47 crate struct TypoSuggestion {
  48     pub candidate: Symbol,
  49     pub res: Res,
  50     pub target: SuggestionTarget,
  51 }
  52
  53 impl TypoSuggestion {
  54     crate fn typo_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
  55         Self { candidate, res, target: SuggestionTarget::SimilarlyNamed }
  56     }
  57     crate fn single_item_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
  58         Self { candidate, res, target: SuggestionTarget::SingleItem }
  59     }
  60 }
  61
  62 /// A free importable items suggested in case of resolution failure.
  63 crate struct ImportSuggestion {
  64     pub did: Option<DefId>,
  65     pub descr: &'static str,
  66     pub path: Path,
  67     pub accessible: bool,
  68     /// An extra note that should be issued if this item is suggested
  69     pub note: Option<String>,
  70 }
  71
  72 /// Adjust the impl span so that just the `impl` keyword is taken by removing
  73 /// everything after `<` (`"impl<T> Iterator for A<T> {}" -> "impl"`) and
  74 /// everything after the first whitespace (`"impl Iterator for A" -> "impl"`).
  75 ///
  76 /// *Attention*: the method used is very fragile since it essentially duplicates the work of the
  77 /// parser. If you need to use this function or something similar, please consider updating the
  78 /// `source_map` functions and this function to something more robust.
  79 fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
  80     let impl_span = sm.span_until_char(impl_span, '<');
  81     sm.span_until_whitespace(impl_span)
  82 }
  83
  84 impl<'a> Resolver<'a> {
  85     crate fn add_module_candidates(
  86         &mut self,
  87         module: Module<'a>,
  88         names: &mut Vec<TypoSuggestion>,
  89         filter_fn: &impl Fn(Res) -> bool,
  90     ) {
  91         for (key, resolution) in self.resolutions(module).borrow().iter() {
  92             if let Some(binding) = resolution.borrow().binding {
  93                 let res = binding.res();
  94                 if filter_fn(res) {
  95                     names.push(TypoSuggestion::typo_from_res(key.ident.name, res));
  96                 }
  97             }
  98         }
  99     }
 100
 101     /// Combines an error with provided span and emits it.
 102     ///
 103     /// This takes the error provided, combines it with the span and any additional spans inside the
 104     /// error and emits it.
 105     crate fn report_error(&self, span: Span, resolution_error: ResolutionError<'_>) {
 106         self.into_struct_error(span, resolution_error).emit();
 107     }
 108
 109     crate fn into_struct_error(
 110         &self,
 111         span: Span,
 112         resolution_error: ResolutionError<'_>,
 113     ) -> DiagnosticBuilder<'_, ErrorGuaranteed> {
 114         match resolution_error {
 115             ResolutionError::GenericParamsFromOuterFunction(outer_res, has_generic_params) => {
 116                 let mut err = struct_span_err!(
 117                     self.session,
 118                     span,
 119                     E0401,
 120                     "can't use generic parameters from outer function",
 121                 );
 122                 err.span_label(span, "use of generic parameter from outer function".to_string());
 123
 124                 let sm = self.session.source_map();
 125                 match outer_res {
 126                     Res::SelfTy { trait_: maybe_trait_defid, alias_to: maybe_impl_defid } => {
 127                         if let Some(impl_span) =
 128                             maybe_impl_defid.and_then(|(def_id, _)| self.opt_span(def_id))
 129                         {
 130                             err.span_label(
 131                                 reduce_impl_span_to_impl_keyword(sm, impl_span),
 132                                 "`Self` type implicitly declared here, by this `impl`",
 133                             );
 134                         }
 135                         match (maybe_trait_defid, maybe_impl_defid) {
 136                             (Some(_), None) => {
 137                                 err.span_label(span, "can't use `Self` here");
 138                             }
 139                             (_, Some(_)) => {
 140                                 err.span_label(span, "use a type here instead");
 141                             }
 142                             (None, None) => bug!("`impl` without trait nor type?"),
 143                         }
 144                         return err;
 145                     }
 146                     Res::Def(DefKind::TyParam, def_id) => {
 147                         if let Some(span) = self.opt_span(def_id) {
 148                             err.span_label(span, "type parameter from outer function");
 149                         }
 150                     }
 151                     Res::Def(DefKind::ConstParam, def_id) => {
 152                         if let Some(span) = self.opt_span(def_id) {
 153                             err.span_label(span, "const parameter from outer function");
 154                         }
 155                     }
 156                     _ => {
 157                         bug!(
 158                             "GenericParamsFromOuterFunction should only be used with Res::SelfTy, \
 159                             DefKind::TyParam or DefKind::ConstParam"
 160                         );
 161                     }
 162                 }
 163
 164                 if has_generic_params == HasGenericParams::Yes {
 165                     // Try to retrieve the span of the function signature and generate a new
 166                     // message with a local type or const parameter.
 167                     let sugg_msg = "try using a local generic parameter instead";
 168                     if let Some((sugg_span, snippet)) = sm.generate_local_type_param_snippet(span) {
 169                         // Suggest the modification to the user
 170                         err.span_suggestion(
 171                             sugg_span,
 172                             sugg_msg,
 173                             snippet,
 174                             Applicability::MachineApplicable,
 175                         );
 176                     } else if let Some(sp) = sm.generate_fn_name_span(span) {
 177                         err.span_label(
 178                             sp,
 179                             "try adding a local generic parameter in this method instead"
 180                                 .to_string(),
 181                         );
 182                     } else {
 183                         err.help("try using a local generic parameter instead");
 184                     }
 185                 }
 186
 187                 err
 188             }
 189             ResolutionError::NameAlreadyUsedInParameterList(name, first_use_span) => {
 190                 let mut err = struct_span_err!(
 191                     self.session,
 192                     span,
 193                     E0403,
 194                     "the name `{}` is already used for a generic \
 195                      parameter in this item's generic parameters",
 196                     name,
 197                 );
 198                 err.span_label(span, "already used");
 199                 err.span_label(first_use_span, format!("first use of `{}`", name));
 200                 err
 201             }
 202             ResolutionError::MethodNotMemberOfTrait(method, trait_, candidate) => {
 203                 let mut err = struct_span_err!(
 204                     self.session,
 205                     span,
 206                     E0407,
 207                     "method `{}` is not a member of trait `{}`",
 208                     method,
 209                     trait_
 210                 );
 211                 err.span_label(span, format!("not a member of trait `{}`", trait_));
 212                 if let Some(candidate) = candidate {
 213                     err.span_suggestion(
 214                         method.span,
 215                         "there is an associated function with a similar name",
 216                         candidate.to_ident_string(),
 217                         Applicability::MaybeIncorrect,
 218                     );
 219                 }
 220                 err
 221             }
 222             ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => {
 223                 let mut err = struct_span_err!(
 224                     self.session,
 225                     span,
 226                     E0437,
 227                     "type `{}` is not a member of trait `{}`",
 228                     type_,
 229                     trait_
 230                 );
 231                 err.span_label(span, format!("not a member of trait `{}`", trait_));
 232                 if let Some(candidate) = candidate {
 233                     err.span_suggestion(
 234                         type_.span,
 235                         "there is an associated type with a similar name",
 236                         candidate.to_ident_string(),
 237                         Applicability::MaybeIncorrect,
 238                     );
 239                 }
 240                 err
 241             }
 242             ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => {
 243                 let mut err = struct_span_err!(
 244                     self.session,
 245                     span,
 246                     E0438,
 247                     "const `{}` is not a member of trait `{}`",
 248                     const_,
 249                     trait_
 250                 );
 251                 err.span_label(span, format!("not a member of trait `{}`", trait_));
 252                 if let Some(candidate) = candidate {
 253                     err.span_suggestion(
 254                         const_.span,
 255                         "there is an associated constant with a similar name",
 256                         candidate.to_ident_string(),
 257                         Applicability::MaybeIncorrect,
 258                     );
 259                 }
 260                 err
 261             }
 262             ResolutionError::VariableNotBoundInPattern(binding_error) => {
 263                 let BindingError { name, target, origin, could_be_path } = binding_error;
 264
 265                 let target_sp = target.iter().copied().collect::<Vec<_>>();
 266                 let origin_sp = origin.iter().copied().collect::<Vec<_>>();
 267
 268                 let msp = MultiSpan::from_spans(target_sp.clone());
 269                 let mut err = struct_span_err!(
 270                     self.session,
 271                     msp,
 272                     E0408,
 273                     "variable `{}` is not bound in all patterns",
 274                     name,
 275                 );
 276                 for sp in target_sp {
 277                     err.span_label(sp, format!("pattern doesn't bind `{}`", name));
 278                 }
 279                 for sp in origin_sp {
 280                     err.span_label(sp, "variable not in all patterns");
 281                 }
 282                 if *could_be_path {
 283                     let help_msg = format!(
 284                         "if you meant to match on a variant or a `const` item, consider \
 285                          making the path in the pattern qualified: `?::{}`",
 286                         name,
 287                     );
 288                     err.span_help(span, &help_msg);
 289                 }
 290                 err
 291             }
 292             ResolutionError::VariableBoundWithDifferentMode(variable_name, first_binding_span) => {
 293                 let mut err = struct_span_err!(
 294                     self.session,
 295                     span,
 296                     E0409,
 297                     "variable `{}` is bound inconsistently across alternatives separated by `|`",
 298                     variable_name
 299                 );
 300                 err.span_label(span, "bound in different ways");
 301                 err.span_label(first_binding_span, "first binding");
 302                 err
 303             }
 304             ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 305                 let mut err = struct_span_err!(
 306                     self.session,
 307                     span,
 308                     E0415,
 309                     "identifier `{}` is bound more than once in this parameter list",
 310                     identifier
 311                 );
 312                 err.span_label(span, "used as parameter more than once");
 313                 err
 314             }
 315             ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 316                 let mut err = struct_span_err!(
 317                     self.session,
 318                     span,
 319                     E0416,
 320                     "identifier `{}` is bound more than once in the same pattern",
 321                     identifier
 322                 );
 323                 err.span_label(span, "used in a pattern more than once");
 324                 err
 325             }
 326             ResolutionError::UndeclaredLabel { name, suggestion } => {
 327                 let mut err = struct_span_err!(
 328                     self.session,
 329                     span,
 330                     E0426,
 331                     "use of undeclared label `{}`",
 332                     name
 333                 );
 334
 335                 err.span_label(span, format!("undeclared label `{}`", name));
 336
 337                 match suggestion {
 338                     // A reachable label with a similar name exists.
 339                     Some((ident, true)) => {
 340                         err.span_label(ident.span, "a label with a similar name is reachable");
 341                         err.span_suggestion(
 342                             span,
 343                             "try using similarly named label",
 344                             ident.name.to_string(),
 345                             Applicability::MaybeIncorrect,
 346                         );
 347                     }
 348                     // An unreachable label with a similar name exists.
 349                     Some((ident, false)) => {
 350                         err.span_label(
 351                             ident.span,
 352                             "a label with a similar name exists but is unreachable",
 353                         );
 354                     }
 355                     // No similarly-named labels exist.
 356                     None => (),
 357                 }
 358
 359                 err
 360             }
 361             ResolutionError::SelfImportsOnlyAllowedWithin { root, span_with_rename } => {
 362                 let mut err = struct_span_err!(
 363                     self.session,
 364                     span,
 365                     E0429,
 366                     "{}",
 367                     "`self` imports are only allowed within a { } list"
 368                 );
 369
 370                 // None of the suggestions below would help with a case like `use self`.
 371                 if !root {
 372                     // use foo::bar::self        -> foo::bar
 373                     // use foo::bar::self as abc -> foo::bar as abc
 374                     err.span_suggestion(
 375                         span,
 376                         "consider importing the module directly",
 377                         "".to_string(),
 378                         Applicability::MachineApplicable,
 379                     );
 380
 381                     // use foo::bar::self        -> foo::bar::{self}
 382                     // use foo::bar::self as abc -> foo::bar::{self as abc}
 383                     let braces = vec![
 384                         (span_with_rename.shrink_to_lo(), "{".to_string()),
 385                         (span_with_rename.shrink_to_hi(), "}".to_string()),
 386                     ];
 387                     err.multipart_suggestion(
 388                         "alternatively, use the multi-path `use` syntax to import `self`",
 389                         braces,
 390                         Applicability::MachineApplicable,
 391                     );
 392                 }
 393                 err
 394             }
 395             ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 396                 let mut err = struct_span_err!(
 397                     self.session,
 398                     span,
 399                     E0430,
 400                     "`self` import can only appear once in an import list"
 401                 );
 402                 err.span_label(span, "can only appear once in an import list");
 403                 err
 404             }
 405             ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 406                 let mut err = struct_span_err!(
 407                     self.session,
 408                     span,
 409                     E0431,
 410                     "`self` import can only appear in an import list with \
 411                                                 a non-empty prefix"
 412                 );
 413                 err.span_label(span, "can only appear in an import list with a non-empty prefix");
 414                 err
 415             }
 416             ResolutionError::FailedToResolve { label, suggestion } => {
 417                 let mut err =
 418                     struct_span_err!(self.session, span, E0433, "failed to resolve: {}", &label);
 419                 err.span_label(span, label);
 420
 421                 if let Some((suggestions, msg, applicability)) = suggestion {
 422                     if suggestions.is_empty() {
 423                         err.help(&msg);
 424                         return err;
 425                     }
 426                     err.multipart_suggestion(&msg, suggestions, applicability);
 427                 }
 428
 429                 err
 430             }
 431             ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 432                 let mut err = struct_span_err!(
 433                     self.session,
 434                     span,
 435                     E0434,
 436                     "{}",
 437                     "can't capture dynamic environment in a fn item"
 438                 );
 439                 err.help("use the `|| { ... }` closure form instead");
 440                 err
 441             }
 442             ResolutionError::AttemptToUseNonConstantValueInConstant(ident, sugg, current) => {
 443                 let mut err = struct_span_err!(
 444                     self.session,
 445                     span,
 446                     E0435,
 447                     "attempt to use a non-constant value in a constant"
 448                 );
 449                 // let foo =...
 450                 //     ^^^ given this Span
 451                 // ------- get this Span to have an applicable suggestion
 452
 453                 // edit:
 454                 // only do this if the const and usage of the non-constant value are on the same line
 455                 // the further the two are apart, the higher the chance of the suggestion being wrong
 456
 457                 let sp = self
 458                     .session
 459                     .source_map()
 460                     .span_extend_to_prev_str(ident.span, current, true, false);
 461
 462                 match sp {
 463                     Some(sp) if !self.session.source_map().is_multiline(sp) => {
 464                         let sp = sp.with_lo(BytePos(sp.lo().0 - (current.len() as u32)));
 465                         err.span_suggestion(
 466                             sp,
 467                             &format!("consider using `{}` instead of `{}`", sugg, current),
 468                             format!("{} {}", sugg, ident),
 469                             Applicability::MaybeIncorrect,
 470                         );
 471                         err.span_label(span, "non-constant value");
 472                     }
 473                     _ => {
 474                         err.span_label(ident.span, &format!("this would need to be a `{}`", sugg));
 475                     }
 476                 }
 477
 478                 err
 479             }
 480             ResolutionError::BindingShadowsSomethingUnacceptable {
 481                 shadowing_binding_descr,
 482                 name,
 483                 participle,
 484                 article,
 485                 shadowed_binding_descr,
 486                 shadowed_binding_span,
 487             } => {
 488                 let mut err = struct_span_err!(
 489                     self.session,
 490                     span,
 491                     E0530,
 492                     "{}s cannot shadow {}s",
 493                     shadowing_binding_descr,
 494                     shadowed_binding_descr,
 495                 );
 496                 err.span_label(
 497                     span,
 498                     format!("cannot be named the same as {} {}", article, shadowed_binding_descr),
 499                 );
 500                 let msg =
 501                     format!("the {} `{}` is {} here", shadowed_binding_descr, name, participle);
 502                 err.span_label(shadowed_binding_span, msg);
 503                 err
 504             }
 505             ResolutionError::ForwardDeclaredGenericParam => {
 506                 let mut err = struct_span_err!(
 507                     self.session,
 508                     span,
 509                     E0128,
 510                     "generic parameters with a default cannot use \
 511                                                 forward declared identifiers"
 512                 );
 513                 err.span_label(
 514                     span,
 515                     "defaulted generic parameters cannot be forward declared".to_string(),
 516                 );
 517                 err
 518             }
 519             ResolutionError::ParamInTyOfConstParam(name) => {
 520                 let mut err = struct_span_err!(
 521                     self.session,
 522                     span,
 523                     E0770,
 524                     "the type of const parameters must not depend on other generic parameters"
 525                 );
 526                 err.span_label(
 527                     span,
 528                     format!("the type must not depend on the parameter `{}`", name),
 529                 );
 530                 err
 531             }
 532             ResolutionError::ParamInNonTrivialAnonConst { name, is_type } => {
 533                 let mut err = self.session.struct_span_err(
 534                     span,
 535                     "generic parameters may not be used in const operations",
 536                 );
 537                 err.span_label(span, &format!("cannot perform const operation using `{}`", name));
 538
 539                 if is_type {
 540                     err.note("type parameters may not be used in const expressions");
 541                 } else {
 542                     err.help(&format!(
 543                         "const parameters may only be used as standalone arguments, i.e. `{}`",
 544                         name
 545                     ));
 546                 }
 547
 548                 if self.session.is_nightly_build() {
 549                     err.help(
 550                         "use `#![feature(generic_const_exprs)]` to allow generic const expressions",
 551                     );
 552                 }
 553
 554                 err
 555             }
 556             ResolutionError::SelfInGenericParamDefault => {
 557                 let mut err = struct_span_err!(
 558                     self.session,
 559                     span,
 560                     E0735,
 561                     "generic parameters cannot use `Self` in their defaults"
 562                 );
 563                 err.span_label(span, "`Self` in generic parameter default".to_string());
 564                 err
 565             }
 566             ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {
 567                 let mut err = struct_span_err!(
 568                     self.session,
 569                     span,
 570                     E0767,
 571                     "use of unreachable label `{}`",
 572                     name,
 573                 );
 574
 575                 err.span_label(definition_span, "unreachable label defined here");
 576                 err.span_label(span, format!("unreachable label `{}`", name));
 577                 err.note(
 578                     "labels are unreachable through functions, closures, async blocks and modules",
 579                 );
 580
 581                 match suggestion {
 582                     // A reachable label with a similar name exists.
 583                     Some((ident, true)) => {
 584                         err.span_label(ident.span, "a label with a similar name is reachable");
 585                         err.span_suggestion(
 586                             span,
 587                             "try using similarly named label",
 588                             ident.name.to_string(),
 589                             Applicability::MaybeIncorrect,
 590                         );
 591                     }
 592                     // An unreachable label with a similar name exists.
 593                     Some((ident, false)) => {
 594                         err.span_label(
 595                             ident.span,
 596                             "a label with a similar name exists but is also unreachable",
 597                         );
 598                     }
 599                     // No similarly-named labels exist.
 600                     None => (),
 601                 }
 602
 603                 err
 604             }
 605             ResolutionError::TraitImplMismatch {
 606                 name,
 607                 kind,
 608                 code,
 609                 trait_item_span,
 610                 trait_path,
 611             } => {
 612                 let mut err = self.session.struct_span_err_with_code(
 613                     span,
 614                     &format!(
 615                         "item `{}` is an associated {}, which doesn't match its trait `{}`",
 616                         name, kind, trait_path,
 617                     ),
 618                     code,
 619                 );
 620                 err.span_label(span, "does not match trait");
 621                 err.span_label(trait_item_span, "item in trait");
 622                 err
 623             }
 624         }
 625     }
 626
 627     crate fn report_vis_error(
 628         &self,
 629         vis_resolution_error: VisResolutionError<'_>,
 630     ) -> ErrorGuaranteed {
 631         match vis_resolution_error {
 632             VisResolutionError::Relative2018(span, path) => {
 633                 let mut err = self.session.struct_span_err(
 634                     span,
 635                     "relative paths are not supported in visibilities on 2018 edition",
 636                 );
 637                 err.span_suggestion(
 638                     path.span,
 639                     "try",
 640                     format!("crate::{}", pprust::path_to_string(&path)),
 641                     Applicability::MaybeIncorrect,
 642                 );
 643                 err
 644             }
 645             VisResolutionError::AncestorOnly(span) => struct_span_err!(
 646                 self.session,
 647                 span,
 648                 E0742,
 649                 "visibilities can only be restricted to ancestor modules"
 650             ),
 651             VisResolutionError::FailedToResolve(span, label, suggestion) => {
 652                 self.into_struct_error(span, ResolutionError::FailedToResolve { label, suggestion })
 653             }
 654             VisResolutionError::ExpectedFound(span, path_str, res) => {
 655                 let mut err = struct_span_err!(
 656                     self.session,
 657                     span,
 658                     E0577,
 659                     "expected module, found {} `{}`",
 660                     res.descr(),
 661                     path_str
 662                 );
 663                 err.span_label(span, "not a module");
 664                 err
 665             }
 666             VisResolutionError::Indeterminate(span) => struct_span_err!(
 667                 self.session,
 668                 span,
 669                 E0578,
 670                 "cannot determine resolution for the visibility"
 671             ),
 672             VisResolutionError::ModuleOnly(span) => {
 673                 self.session.struct_span_err(span, "visibility must resolve to a module")
 674             }
 675         }
 676         .emit()
 677     }
 678
 679     /// Lookup typo candidate in scope for a macro or import.
 680     fn early_lookup_typo_candidate(
 681         &mut self,
 682         scope_set: ScopeSet<'a>,
 683         parent_scope: &ParentScope<'a>,
 684         ident: Ident,
 685         filter_fn: &impl Fn(Res) -> bool,
 686     ) -> Option<TypoSuggestion> {
 687         let mut suggestions = Vec::new();
 688         let ctxt = ident.span.ctxt();
 689         self.visit_scopes(scope_set, parent_scope, ctxt, |this, scope, use_prelude, _| {
 690             match scope {
 691                 Scope::DeriveHelpers(expn_id) => {
 692                     let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
 693                     if filter_fn(res) {
 694                         suggestions.extend(
 695                             this.helper_attrs
 696                                 .get(&expn_id)
 697                                 .into_iter()
 698                                 .flatten()
 699                                 .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
 700                         );
 701                     }
 702                 }
 703                 Scope::DeriveHelpersCompat => {
 704                     let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
 705                     if filter_fn(res) {
 706                         for derive in parent_scope.derives {
 707                             let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
 708                             if let Ok((Some(ext), _)) = this.resolve_macro_path(
 709                                 derive,
 710                                 Some(MacroKind::Derive),
 711                                 parent_scope,
 712                                 false,
 713                                 false,
 714                             ) {
 715                                 suggestions.extend(
 716                                     ext.helper_attrs
 717                                         .iter()
 718                                         .map(|name| TypoSuggestion::typo_from_res(*name, res)),
 719                                 );
 720                             }
 721                         }
 722                     }
 723                 }
 724                 Scope::MacroRules(macro_rules_scope) => {
 725                     if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
 726                         let res = macro_rules_binding.binding.res();
 727                         if filter_fn(res) {
 728                             suggestions.push(TypoSuggestion::typo_from_res(
 729                                 macro_rules_binding.ident.name,
 730                                 res,
 731                             ))
 732                         }
 733                     }
 734                 }
 735                 Scope::CrateRoot => {
 736                     let root_ident = Ident::new(kw::PathRoot, ident.span);
 737                     let root_module = this.resolve_crate_root(root_ident);
 738                     this.add_module_candidates(root_module, &mut suggestions, filter_fn);
 739                 }
 740                 Scope::Module(module, _) => {
 741                     this.add_module_candidates(module, &mut suggestions, filter_fn);
 742                 }
 743                 Scope::RegisteredAttrs => {
 744                     let res = Res::NonMacroAttr(NonMacroAttrKind::Registered);
 745                     if filter_fn(res) {
 746                         suggestions.extend(
 747                             this.registered_attrs
 748                                 .iter()
 749                                 .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
 750                         );
 751                     }
 752                 }
 753                 Scope::MacroUsePrelude => {
 754                     suggestions.extend(this.macro_use_prelude.iter().filter_map(
 755                         |(name, binding)| {
 756                             let res = binding.res();
 757                             filter_fn(res).then_some(TypoSuggestion::typo_from_res(*name, res))
 758                         },
 759                     ));
 760                 }
 761                 Scope::BuiltinAttrs => {
 762                     let res = Res::NonMacroAttr(NonMacroAttrKind::Builtin(kw::Empty));
 763                     if filter_fn(res) {
 764                         suggestions.extend(
 765                             BUILTIN_ATTRIBUTES
 766                                 .iter()
 767                                 .map(|attr| TypoSuggestion::typo_from_res(attr.name, res)),
 768                         );
 769                     }
 770                 }
 771                 Scope::ExternPrelude => {
 772                     suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
 773                         let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
 774                         filter_fn(res).then_some(TypoSuggestion::typo_from_res(ident.name, res))
 775                     }));
 776                 }
 777                 Scope::ToolPrelude => {
 778                     let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
 779                     suggestions.extend(
 780                         this.registered_tools
 781                             .iter()
 782                             .map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
 783                     );
 784                 }
 785                 Scope::StdLibPrelude => {
 786                     if let Some(prelude) = this.prelude {
 787                         let mut tmp_suggestions = Vec::new();
 788                         this.add_module_candidates(prelude, &mut tmp_suggestions, filter_fn);
 789                         suggestions.extend(
 790                             tmp_suggestions
 791                                 .into_iter()
 792                                 .filter(|s| use_prelude || this.is_builtin_macro(s.res)),
 793                         );
 794                     }
 795                 }
 796                 Scope::BuiltinTypes => {
 797                     suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| {
 798                         let res = Res::PrimTy(*prim_ty);
 799                         filter_fn(res).then_some(TypoSuggestion::typo_from_res(prim_ty.name(), res))
 800                     }))
 801                 }
 802             }
 803
 804             None::<()>
 805         });
 806
 807         // Make sure error reporting is deterministic.
 808         suggestions.sort_by(|a, b| a.candidate.as_str().partial_cmp(b.candidate.as_str()).unwrap());
 809
 810         match find_best_match_for_name(
 811             &suggestions.iter().map(|suggestion| suggestion.candidate).collect::<Vec<Symbol>>(),
 812             ident.name,
 813             None,
 814         ) {
 815             Some(found) if found != ident.name => {
 816                 suggestions.into_iter().find(|suggestion| suggestion.candidate == found)
 817             }
 818             _ => None,
 819         }
 820     }
 821
 822     fn lookup_import_candidates_from_module<FilterFn>(
 823         &mut self,
 824         lookup_ident: Ident,
 825         namespace: Namespace,
 826         parent_scope: &ParentScope<'a>,
 827         start_module: Module<'a>,
 828         crate_name: Ident,
 829         filter_fn: FilterFn,
 830     ) -> Vec<ImportSuggestion>
 831     where
 832         FilterFn: Fn(Res) -> bool,
 833     {
 834         let mut candidates = Vec::new();
 835         let mut seen_modules = FxHashSet::default();
 836         let mut worklist = vec![(start_module, Vec::<ast::PathSegment>::new(), true)];
 837         let mut worklist_via_import = vec![];
 838
 839         while let Some((in_module, path_segments, accessible)) = match worklist.pop() {
 840             None => worklist_via_import.pop(),
 841             Some(x) => Some(x),
 842         } {
 843             let in_module_is_extern = !in_module.def_id().is_local();
 844             // We have to visit module children in deterministic order to avoid
 845             // instabilities in reported imports (#43552).
 846             in_module.for_each_child(self, |this, ident, ns, name_binding| {
 847                 // avoid non-importable candidates
 848                 if !name_binding.is_importable() {
 849                     return;
 850                 }
 851
 852                 let child_accessible =
 853                     accessible && this.is_accessible_from(name_binding.vis, parent_scope.module);
 854
 855                 // do not venture inside inaccessible items of other crates
 856                 if in_module_is_extern && !child_accessible {
 857                     return;
 858                 }
 859
 860                 let via_import = name_binding.is_import() && !name_binding.is_extern_crate();
 861
 862                 // There is an assumption elsewhere that paths of variants are in the enum's
 863                 // declaration and not imported. With this assumption, the variant component is
 864                 // chopped and the rest of the path is assumed to be the enum's own path. For
 865                 // errors where a variant is used as the type instead of the enum, this causes
 866                 // funny looking invalid suggestions, i.e `foo` instead of `foo::MyEnum`.
 867                 if via_import && name_binding.is_possibly_imported_variant() {
 868                     return;
 869                 }
 870
 871                 // #90113: Do not count an inaccessible reexported item as a candidate.
 872                 if let NameBindingKind::Import { binding, .. } = name_binding.kind {
 873                     if this.is_accessible_from(binding.vis, parent_scope.module)
 874                         && !this.is_accessible_from(name_binding.vis, parent_scope.module)
 875                     {
 876                         return;
 877                     }
 878                 }
 879
 880                 // collect results based on the filter function
 881                 // avoid suggesting anything from the same module in which we are resolving
 882                 // avoid suggesting anything with a hygienic name
 883                 if ident.name == lookup_ident.name
 884                     && ns == namespace
 885                     && !ptr::eq(in_module, parent_scope.module)
 886                     && !ident.span.normalize_to_macros_2_0().from_expansion()
 887                 {
 888                     let res = name_binding.res();
 889                     if filter_fn(res) {
 890                         // create the path
 891                         let mut segms = path_segments.clone();
 892                         if lookup_ident.span.rust_2018() {
 893                             // crate-local absolute paths start with `crate::` in edition 2018
 894                             // FIXME: may also be stabilized for Rust 2015 (Issues #45477, #44660)
 895                             segms.insert(0, ast::PathSegment::from_ident(crate_name));
 896                         }
 897
 898                         segms.push(ast::PathSegment::from_ident(ident));
 899                         let path = Path { span: name_binding.span, segments: segms, tokens: None };
 900                         let did = match res {
 901                             Res::Def(DefKind::Ctor(..), did) => this.parent(did),
 902                             _ => res.opt_def_id(),
 903                         };
 904
 905                         if child_accessible {
 906                             // Remove invisible match if exists
 907                             if let Some(idx) = candidates
 908                                 .iter()
 909                                 .position(|v: &ImportSuggestion| v.did == did && !v.accessible)
 910                             {
 911                                 candidates.remove(idx);
 912                             }
 913                         }
 914
 915                         if candidates.iter().all(|v: &ImportSuggestion| v.did != did) {
 916                             // See if we're recommending TryFrom, TryInto, or FromIterator and add
 917                             // a note about editions
 918                             let note = if let Some(did) = did {
 919                                 let requires_note = !did.is_local()
 920                                     && this.cstore().item_attrs_untracked(did, this.session).any(
 921                                         |attr| {
 922                                             if attr.has_name(sym::rustc_diagnostic_item) {
 923                                                 [sym::TryInto, sym::TryFrom, sym::FromIterator]
 924                                                     .map(|x| Some(x))
 925                                                     .contains(&attr.value_str())
 926                                             } else {
 927                                                 false
 928                                             }
 929                                         },
 930                                     );
 931
 932                                 requires_note.then(|| {
 933                                     format!(
 934                                         "'{}' is included in the prelude starting in Edition 2021",
 935                                         path_names_to_string(&path)
 936                                     )
 937                                 })
 938                             } else {
 939                                 None
 940                             };
 941
 942                             candidates.push(ImportSuggestion {
 943                                 did,
 944                                 descr: res.descr(),
 945                                 path,
 946                                 accessible: child_accessible,
 947                                 note,
 948                             });
 949                         }
 950                     }
 951                 }
 952
 953                 // collect submodules to explore
 954                 if let Some(module) = name_binding.module() {
 955                     // form the path
 956                     let mut path_segments = path_segments.clone();
 957                     path_segments.push(ast::PathSegment::from_ident(ident));
 958
 959                     let is_extern_crate_that_also_appears_in_prelude =
 960                         name_binding.is_extern_crate() && lookup_ident.span.rust_2018();
 961
 962                     if !is_extern_crate_that_also_appears_in_prelude {
 963                         // add the module to the lookup
 964                         if seen_modules.insert(module.def_id()) {
 965                             if via_import { &mut worklist_via_import } else { &mut worklist }
 966                                 .push((module, path_segments, child_accessible));
 967                         }
 968                     }
 969                 }
 970             })
 971         }
 972
 973         // If only some candidates are accessible, take just them
 974         if !candidates.iter().all(|v: &ImportSuggestion| !v.accessible) {
 975             candidates = candidates.into_iter().filter(|x| x.accessible).collect();
 976         }
 977
 978         candidates
 979     }
 980
 981     /// When name resolution fails, this method can be used to look up candidate
 982     /// entities with the expected name. It allows filtering them using the
 983     /// supplied predicate (which should be used to only accept the types of
 984     /// definitions expected, e.g., traits). The lookup spans across all crates.
 985     ///
 986     /// N.B., the method does not look into imports, but this is not a problem,
 987     /// since we report the definitions (thus, the de-aliased imports).
 988     crate fn lookup_import_candidates<FilterFn>(
 989         &mut self,
 990         lookup_ident: Ident,
 991         namespace: Namespace,
 992         parent_scope: &ParentScope<'a>,
 993         filter_fn: FilterFn,
 994     ) -> Vec<ImportSuggestion>
 995     where
 996         FilterFn: Fn(Res) -> bool,
 997     {
 998         let mut suggestions = self.lookup_import_candidates_from_module(
 999             lookup_ident,
1000             namespace,
1001             parent_scope,
1002             self.graph_root,
1003             Ident::with_dummy_span(kw::Crate),
1004             &filter_fn,
1005         );
1006
1007         if lookup_ident.span.rust_2018() {
1008             let extern_prelude_names = self.extern_prelude.clone();
1009             for (ident, _) in extern_prelude_names.into_iter() {
1010                 if ident.span.from_expansion() {
1011                     // Idents are adjusted to the root context before being
1012                     // resolved in the extern prelude, so reporting this to the
1013                     // user is no help. This skips the injected
1014                     // `extern crate std` in the 2018 edition, which would
1015                     // otherwise cause duplicate suggestions.
1016                     continue;
1017                 }
1018                 if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
1019                     let crate_root = self.expect_module(crate_id.as_def_id());
1020                     suggestions.extend(self.lookup_import_candidates_from_module(
1021                         lookup_ident,
1022                         namespace,
1023                         parent_scope,
1024                         crate_root,
1025                         ident,
1026                         &filter_fn,
1027                     ));
1028                 }
1029             }
1030         }
1031
1032         suggestions
1033     }
1034
1035     crate fn unresolved_macro_suggestions(
1036         &mut self,
1037         err: &mut Diagnostic,
1038         macro_kind: MacroKind,
1039         parent_scope: &ParentScope<'a>,
1040         ident: Ident,
1041     ) {
1042         let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
1043         let suggestion = self.early_lookup_typo_candidate(
1044             ScopeSet::Macro(macro_kind),
1045             parent_scope,
1046             ident,
1047             is_expected,
1048         );
1049         self.add_typo_suggestion(err, suggestion, ident.span);
1050
1051         let import_suggestions =
1052             self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected);
1053         show_candidates(
1054             &self.definitions,
1055             self.session,
1056             err,
1057             None,
1058             &import_suggestions,
1059             false,
1060             true,
1061         );
1062
1063         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
1064             let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
1065             err.span_note(ident.span, &msg);
1066             return;
1067         }
1068         if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
1069             err.help("have you added the `#[macro_use]` on the module/import?");
1070             return;
1071         }
1072         for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
1073             if let Ok(binding) = self.early_resolve_ident_in_lexical_scope(
1074                 ident,
1075                 ScopeSet::All(ns, false),
1076                 &parent_scope,
1077                 None,
1078                 false,
1079             ) {
1080                 let desc = match binding.res() {
1081                     Res::Def(DefKind::Macro(MacroKind::Bang), _) => {
1082                         "a function-like macro".to_string()
1083                     }
1084                     Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => {
1085                         format!("an attribute: `#[{}]`", ident)
1086                     }
1087                     Res::Def(DefKind::Macro(MacroKind::Derive), _) => {
1088                         format!("a derive macro: `#[derive({})]`", ident)
1089                     }
1090                     Res::ToolMod => {
1091                         // Don't confuse the user with tool modules.
1092                         continue;
1093                     }
1094                     Res::Def(DefKind::Trait, _) if macro_kind == MacroKind::Derive => {
1095                         "only a trait, without a derive macro".to_string()
1096                     }
1097                     res => format!(
1098                         "{} {}, not {} {}",
1099                         res.article(),
1100                         res.descr(),
1101                         macro_kind.article(),
1102                         macro_kind.descr_expected(),
1103                     ),
1104                 };
1105                 if let crate::NameBindingKind::Import { import, .. } = binding.kind {
1106                     if !import.span.is_dummy() {
1107                         err.span_note(
1108                             import.span,
1109                             &format!("`{}` is imported here, but it is {}", ident, desc),
1110                         );
1111                         // Silence the 'unused import' warning we might get,
1112                         // since this diagnostic already covers that import.
1113                         self.record_use(ident, binding, false);
1114                         return;
1115                     }
1116                 }
1117                 err.note(&format!("`{}` is in scope, but it is {}", ident, desc));
1118                 return;
1119             }
1120         }
1121     }
1122
1123     crate fn add_typo_suggestion(
1124         &self,
1125         err: &mut Diagnostic,
1126         suggestion: Option<TypoSuggestion>,
1127         span: Span,
1128     ) -> bool {
1129         let suggestion = match suggestion {
1130             None => return false,
1131             // We shouldn't suggest underscore.
1132             Some(suggestion) if suggestion.candidate == kw::Underscore => return false,
1133             Some(suggestion) => suggestion,
1134         };
1135         let def_span = suggestion.res.opt_def_id().and_then(|def_id| match def_id.krate {
1136             LOCAL_CRATE => self.opt_span(def_id),
1137             _ => Some(
1138                 self.session
1139                     .source_map()
1140                     .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
1141             ),
1142         });
1143         if let Some(def_span) = def_span {
1144             if span.overlaps(def_span) {
1145                 // Don't suggest typo suggestion for itself like in the following:
1146                 // error[E0423]: expected function, tuple struct or tuple variant, found struct `X`
1147                 //   --> $DIR/issue-64792-bad-unicode-ctor.rs:3:14
1148                 //    |
1149                 // LL | struct X {}
1150                 //    | ----------- `X` defined here
1151                 // LL |
1152                 // LL | const Y: X = X("ö");
1153                 //    | -------------^^^^^^- similarly named constant `Y` defined here
1154                 //    |
1155                 // help: use struct literal syntax instead
1156                 //    |
1157                 // LL | const Y: X = X {};
1158                 //    |              ^^^^
1159                 // help: a constant with a similar name exists
1160                 //    |
1161                 // LL | const Y: X = Y("ö");
1162                 //    |              ^
1163                 return false;
1164             }
1165             let prefix = match suggestion.target {
1166                 SuggestionTarget::SimilarlyNamed => "similarly named ",
1167                 SuggestionTarget::SingleItem => "",
1168             };
1169
1170             err.span_label(
1171                 self.session.source_map().guess_head_span(def_span),
1172                 &format!(
1173                     "{}{} `{}` defined here",
1174                     prefix,
1175                     suggestion.res.descr(),
1176                     suggestion.candidate.as_str(),
1177                 ),
1178             );
1179         }
1180         let msg = match suggestion.target {
1181             SuggestionTarget::SimilarlyNamed => format!(
1182                 "{} {} with a similar name exists",
1183                 suggestion.res.article(),
1184                 suggestion.res.descr()
1185             ),
1186             SuggestionTarget::SingleItem => {
1187                 format!("maybe you meant this {}", suggestion.res.descr())
1188             }
1189         };
1190         err.span_suggestion(
1191             span,
1192             &msg,
1193             suggestion.candidate.to_string(),
1194             Applicability::MaybeIncorrect,
1195         );
1196         true
1197     }
1198
1199     fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
1200         let res = b.res();
1201         if b.span.is_dummy() || self.session.source_map().span_to_snippet(b.span).is_err() {
1202             // These already contain the "built-in" prefix or look bad with it.
1203             let add_built_in =
1204                 !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);
1205             let (built_in, from) = if from_prelude {
1206                 ("", " from prelude")
1207             } else if b.is_extern_crate()
1208                 && !b.is_import()
1209                 && self.session.opts.externs.get(ident.as_str()).is_some()
1210             {
1211                 ("", " passed with `--extern`")
1212             } else if add_built_in {
1213                 (" built-in", "")
1214             } else {
1215                 ("", "")
1216             };
1217
1218             let a = if built_in.is_empty() { res.article() } else { "a" };
1219             format!("{a}{built_in} {thing}{from}", thing = res.descr())
1220         } else {
1221             let introduced = if b.is_import() { "imported" } else { "defined" };
1222             format!("the {thing} {introduced} here", thing = res.descr())
1223         }
1224     }
1225
1226     crate fn report_ambiguity_error(&self, ambiguity_error: &AmbiguityError<'_>) {
1227         let AmbiguityError { kind, ident, b1, b2, misc1, misc2 } = *ambiguity_error;
1228         let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
1229             // We have to print the span-less alternative first, otherwise formatting looks bad.
1230             (b2, b1, misc2, misc1, true)
1231         } else {
1232             (b1, b2, misc1, misc2, false)
1233         };
1234
1235         let mut err = struct_span_err!(self.session, ident.span, E0659, "`{ident}` is ambiguous");
1236         err.span_label(ident.span, "ambiguous name");
1237         err.note(&format!("ambiguous because of {}", kind.descr()));
1238
1239         let mut could_refer_to = |b: &NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
1240             let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
1241             let note_msg = format!("`{ident}` could{also} refer to {what}");
1242
1243             let thing = b.res().descr();
1244             let mut help_msgs = Vec::new();
1245             if b.is_glob_import()
1246                 && (kind == AmbiguityKind::GlobVsGlob
1247                     || kind == AmbiguityKind::GlobVsExpanded
1248                     || kind == AmbiguityKind::GlobVsOuter && swapped != also.is_empty())
1249             {
1250                 help_msgs.push(format!(
1251                     "consider adding an explicit import of `{ident}` to disambiguate"
1252                 ))
1253             }
1254             if b.is_extern_crate() && ident.span.rust_2018() {
1255                 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
1256             }
1257             if misc == AmbiguityErrorMisc::SuggestCrate {
1258                 help_msgs
1259                     .push(format!("use `crate::{ident}` to refer to this {thing} unambiguously"))
1260             } else if misc == AmbiguityErrorMisc::SuggestSelf {
1261                 help_msgs
1262                     .push(format!("use `self::{ident}` to refer to this {thing} unambiguously"))
1263             }
1264
1265             err.span_note(b.span, &note_msg);
1266             for (i, help_msg) in help_msgs.iter().enumerate() {
1267                 let or = if i == 0 { "" } else { "or " };
1268                 err.help(&format!("{}{}", or, help_msg));
1269             }
1270         };
1271
1272         could_refer_to(b1, misc1, "");
1273         could_refer_to(b2, misc2, " also");
1274         err.emit();
1275     }
1276
1277     /// If the binding refers to a tuple struct constructor with fields,
1278     /// returns the span of its fields.
1279     fn ctor_fields_span(&self, binding: &NameBinding<'_>) -> Option<Span> {
1280         if let NameBindingKind::Res(
1281             Res::Def(DefKind::Ctor(CtorOf::Struct, CtorKind::Fn), ctor_def_id),
1282             _,
1283         ) = binding.kind
1284         {
1285             let def_id = self.parent(ctor_def_id).expect("no parent for a constructor");
1286             let fields = self.field_names.get(&def_id)?;
1287             return fields.iter().map(|name| name.span).reduce(Span::to); // None for `struct Foo()`
1288         }
1289         None
1290     }
1291
1292     crate fn report_privacy_error(&self, privacy_error: &PrivacyError<'_>) {
1293         let PrivacyError { ident, binding, .. } = *privacy_error;
1294
1295         let res = binding.res();
1296         let ctor_fields_span = self.ctor_fields_span(binding);
1297         let plain_descr = res.descr().to_string();
1298         let nonimport_descr =
1299             if ctor_fields_span.is_some() { plain_descr + " constructor" } else { plain_descr };
1300         let import_descr = nonimport_descr.clone() + " import";
1301         let get_descr =
1302             |b: &NameBinding<'_>| if b.is_import() { &import_descr } else { &nonimport_descr };
1303
1304         // Print the primary message.
1305         let descr = get_descr(binding);
1306         let mut err =
1307             struct_span_err!(self.session, ident.span, E0603, "{} `{}` is private", descr, ident);
1308         err.span_label(ident.span, &format!("private {}", descr));
1309         if let Some(span) = ctor_fields_span {
1310             err.span_label(span, "a constructor is private if any of the fields is private");
1311         }
1312
1313         // Print the whole import chain to make it easier to see what happens.
1314         let first_binding = binding;
1315         let mut next_binding = Some(binding);
1316         let mut next_ident = ident;
1317         while let Some(binding) = next_binding {
1318             let name = next_ident;
1319             next_binding = match binding.kind {
1320                 _ if res == Res::Err => None,
1321                 NameBindingKind::Import { binding, import, .. } => match import.kind {
1322                     _ if binding.span.is_dummy() => None,
1323                     ImportKind::Single { source, .. } => {
1324                         next_ident = source;
1325                         Some(binding)
1326                     }
1327                     ImportKind::Glob { .. } | ImportKind::MacroUse => Some(binding),
1328                     ImportKind::ExternCrate { .. } => None,
1329                 },
1330                 _ => None,
1331             };
1332
1333             let first = ptr::eq(binding, first_binding);
1334             let msg = format!(
1335                 "{and_refers_to}the {item} `{name}`{which} is defined here{dots}",
1336                 and_refers_to = if first { "" } else { "...and refers to " },
1337                 item = get_descr(binding),
1338                 which = if first { "" } else { " which" },
1339                 dots = if next_binding.is_some() { "..." } else { "" },
1340             );
1341             let def_span = self.session.source_map().guess_head_span(binding.span);
1342             let mut note_span = MultiSpan::from_span(def_span);
1343             if !first && binding.vis.is_public() {
1344                 note_span.push_span_label(def_span, "consider importing it directly");
1345             }
1346             err.span_note(note_span, &msg);
1347         }
1348
1349         err.emit();
1350     }
1351
1352     crate fn find_similarly_named_module_or_crate(
1353         &mut self,
1354         ident: Symbol,
1355         current_module: &Module<'a>,
1356     ) -> Option<Symbol> {
1357         let mut candidates = self
1358             .extern_prelude
1359             .iter()
1360             .map(|(ident, _)| ident.name)
1361             .chain(
1362                 self.module_map
1363                     .iter()
1364                     .filter(|(_, module)| {
1365                         current_module.is_ancestor_of(module) && !ptr::eq(current_module, *module)
1366                     })
1367                     .flat_map(|(_, module)| module.kind.name()),
1368             )
1369             .filter(|c| !c.to_string().is_empty())
1370             .collect::<Vec<_>>();
1371         candidates.sort();
1372         candidates.dedup();
1373         match find_best_match_for_name(&candidates, ident, None) {
1374             Some(sugg) if sugg == ident => None,
1375             sugg => sugg,
1376         }
1377     }
1378 }
1379
1380 impl<'a, 'b> ImportResolver<'a, 'b> {
1381     /// Adds suggestions for a path that cannot be resolved.
1382     pub(crate) fn make_path_suggestion(
1383         &mut self,
1384         span: Span,
1385         mut path: Vec<Segment>,
1386         parent_scope: &ParentScope<'b>,
1387     ) -> Option<(Vec<Segment>, Vec<String>)> {
1388         debug!("make_path_suggestion: span={:?} path={:?}", span, path);
1389
1390         match (path.get(0), path.get(1)) {
1391             // `{{root}}::ident::...` on both editions.
1392             // On 2015 `{{root}}` is usually added implicitly.
1393             (Some(fst), Some(snd))
1394                 if fst.ident.name == kw::PathRoot && !snd.ident.is_path_segment_keyword() => {}
1395             // `ident::...` on 2018.
1396             (Some(fst), _)
1397                 if fst.ident.span.rust_2018() && !fst.ident.is_path_segment_keyword() =>
1398             {
1399                 // Insert a placeholder that's later replaced by `self`/`super`/etc.
1400                 path.insert(0, Segment::from_ident(Ident::empty()));
1401             }
1402             _ => return None,
1403         }
1404
1405         self.make_missing_self_suggestion(path.clone(), parent_scope)
1406             .or_else(|| self.make_missing_crate_suggestion(path.clone(), parent_scope))
1407             .or_else(|| self.make_missing_super_suggestion(path.clone(), parent_scope))
1408             .or_else(|| self.make_external_crate_suggestion(path, parent_scope))
1409     }
1410
1411     /// Suggest a missing `self::` if that resolves to an correct module.
1412     ///
1413     /// ```text
1414     ///    |
1415     /// LL | use foo::Bar;
1416     ///    |     ^^^ did you mean `self::foo`?
1417     /// ```
1418     fn make_missing_self_suggestion(
1419         &mut self,
1420         mut path: Vec<Segment>,
1421         parent_scope: &ParentScope<'b>,
1422     ) -> Option<(Vec<Segment>, Vec<String>)> {
1423         // Replace first ident with `self` and check if that is valid.
1424         path[0].ident.name = kw::SelfLower;
1425         let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1426         debug!("make_missing_self_suggestion: path={:?} result={:?}", path, result);
1427         if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1428     }
1429
1430     /// Suggests a missing `crate::` if that resolves to an correct module.
1431     ///
1432     /// ```text
1433     ///    |
1434     /// LL | use foo::Bar;
1435     ///    |     ^^^ did you mean `crate::foo`?
1436     /// ```
1437     fn make_missing_crate_suggestion(
1438         &mut self,
1439         mut path: Vec<Segment>,
1440         parent_scope: &ParentScope<'b>,
1441     ) -> Option<(Vec<Segment>, Vec<String>)> {
1442         // Replace first ident with `crate` and check if that is valid.
1443         path[0].ident.name = kw::Crate;
1444         let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1445         debug!("make_missing_crate_suggestion:  path={:?} result={:?}", path, result);
1446         if let PathResult::Module(..) = result {
1447             Some((
1448                 path,
1449                 vec![
1450                     "`use` statements changed in Rust 2018; read more at \
1451                      <https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-\
1452                      clarity.html>"
1453                         .to_string(),
1454                 ],
1455             ))
1456         } else {
1457             None
1458         }
1459     }
1460
1461     /// Suggests a missing `super::` if that resolves to an correct module.
1462     ///
1463     /// ```text
1464     ///    |
1465     /// LL | use foo::Bar;
1466     ///    |     ^^^ did you mean `super::foo`?
1467     /// ```
1468     fn make_missing_super_suggestion(
1469         &mut self,
1470         mut path: Vec<Segment>,
1471         parent_scope: &ParentScope<'b>,
1472     ) -> Option<(Vec<Segment>, Vec<String>)> {
1473         // Replace first ident with `crate` and check if that is valid.
1474         path[0].ident.name = kw::Super;
1475         let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1476         debug!("make_missing_super_suggestion:  path={:?} result={:?}", path, result);
1477         if let PathResult::Module(..) = result { Some((path, Vec::new())) } else { None }
1478     }
1479
1480     /// Suggests a missing external crate name if that resolves to an correct module.
1481     ///
1482     /// ```text
1483     ///    |
1484     /// LL | use foobar::Baz;
1485     ///    |     ^^^^^^ did you mean `baz::foobar`?
1486     /// ```
1487     ///
1488     /// Used when importing a submodule of an external crate but missing that crate's
1489     /// name as the first part of path.
1490     fn make_external_crate_suggestion(
1491         &mut self,
1492         mut path: Vec<Segment>,
1493         parent_scope: &ParentScope<'b>,
1494     ) -> Option<(Vec<Segment>, Vec<String>)> {
1495         if path[1].ident.span.rust_2015() {
1496             return None;
1497         }
1498
1499         // Sort extern crate names in *reverse* order to get
1500         // 1) some consistent ordering for emitted diagnostics, and
1501         // 2) `std` suggestions before `core` suggestions.
1502         let mut extern_crate_names =
1503             self.r.extern_prelude.iter().map(|(ident, _)| ident.name).collect::<Vec<_>>();
1504         extern_crate_names.sort_by(|a, b| b.as_str().partial_cmp(a.as_str()).unwrap());
1505
1506         for name in extern_crate_names.into_iter() {
1507             // Replace first ident with a crate name and check if that is valid.
1508             path[0].ident.name = name;
1509             let result = self.r.resolve_path(&path, None, parent_scope, Finalize::No);
1510             debug!(
1511                 "make_external_crate_suggestion: name={:?} path={:?} result={:?}",
1512                 name, path, result
1513             );
1514             if let PathResult::Module(..) = result {
1515                 return Some((path, Vec::new()));
1516             }
1517         }
1518
1519         None
1520     }
1521
1522     /// Suggests importing a macro from the root of the crate rather than a module within
1523     /// the crate.
1524     ///
1525     /// ```text
1526     /// help: a macro with this name exists at the root of the crate
1527     ///    |
1528     /// LL | use issue_59764::makro;
1529     ///    |     ^^^^^^^^^^^^^^^^^^
1530     ///    |
1531     ///    = note: this could be because a macro annotated with `#[macro_export]` will be exported
1532     ///            at the root of the crate instead of the module where it is defined
1533     /// ```
1534     pub(crate) fn check_for_module_export_macro(
1535         &mut self,
1536         import: &'b Import<'b>,
1537         module: ModuleOrUniformRoot<'b>,
1538         ident: Ident,
1539     ) -> Option<(Option<Suggestion>, Vec<String>)> {
1540         let ModuleOrUniformRoot::Module(mut crate_module) = module else {
1541             return None;
1542         };
1543
1544         while let Some(parent) = crate_module.parent {
1545             crate_module = parent;
1546         }
1547
1548         if ModuleOrUniformRoot::same_def(ModuleOrUniformRoot::Module(crate_module), module) {
1549             // Don't make a suggestion if the import was already from the root of the
1550             // crate.
1551             return None;
1552         }
1553
1554         let resolutions = self.r.resolutions(crate_module).borrow();
1555         let resolution = resolutions.get(&self.r.new_key(ident, MacroNS))?;
1556         let binding = resolution.borrow().binding()?;
1557         if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
1558             let module_name = crate_module.kind.name().unwrap();
1559             let import_snippet = match import.kind {
1560                 ImportKind::Single { source, target, .. } if source != target => {
1561                     format!("{} as {}", source, target)
1562                 }
1563                 _ => format!("{}", ident),
1564             };
1565
1566             let mut corrections: Vec<(Span, String)> = Vec::new();
1567             if !import.is_nested() {
1568                 // Assume this is the easy case of `use issue_59764::foo::makro;` and just remove
1569                 // intermediate segments.
1570                 corrections.push((import.span, format!("{}::{}", module_name, import_snippet)));
1571             } else {
1572                 // Find the binding span (and any trailing commas and spaces).
1573                 //   ie. `use a::b::{c, d, e};`
1574                 //                      ^^^
1575                 let (found_closing_brace, binding_span) = find_span_of_binding_until_next_binding(
1576                     self.r.session,
1577                     import.span,
1578                     import.use_span,
1579                 );
1580                 debug!(
1581                     "check_for_module_export_macro: found_closing_brace={:?} binding_span={:?}",
1582                     found_closing_brace, binding_span
1583                 );
1584
1585                 let mut removal_span = binding_span;
1586                 if found_closing_brace {
1587                     // If the binding span ended with a closing brace, as in the below example:
1588                     //   ie. `use a::b::{c, d};`
1589                     //                      ^
1590                     // Then expand the span of characters to remove to include the previous
1591                     // binding's trailing comma.
1592                     //   ie. `use a::b::{c, d};`
1593                     //                    ^^^
1594                     if let Some(previous_span) =
1595                         extend_span_to_previous_binding(self.r.session, binding_span)
1596                     {
1597                         debug!("check_for_module_export_macro: previous_span={:?}", previous_span);
1598                         removal_span = removal_span.with_lo(previous_span.lo());
1599                     }
1600                 }
1601                 debug!("check_for_module_export_macro: removal_span={:?}", removal_span);
1602
1603                 // Remove the `removal_span`.
1604                 corrections.push((removal_span, "".to_string()));
1605
1606                 // Find the span after the crate name and if it has nested imports immediately
1607                 // after the crate name already.
1608                 //   ie. `use a::b::{c, d};`
1609                 //               ^^^^^^^^^
1610                 //   or  `use a::{b, c, d}};`
1611                 //               ^^^^^^^^^^^
1612                 let (has_nested, after_crate_name) = find_span_immediately_after_crate_name(
1613                     self.r.session,
1614                     module_name,
1615                     import.use_span,
1616                 );
1617                 debug!(
1618                     "check_for_module_export_macro: has_nested={:?} after_crate_name={:?}",
1619                     has_nested, after_crate_name
1620                 );
1621
1622                 let source_map = self.r.session.source_map();
1623
1624                 // Add the import to the start, with a `{` if required.
1625                 let start_point = source_map.start_point(after_crate_name);
1626                 if let Ok(start_snippet) = source_map.span_to_snippet(start_point) {
1627                     corrections.push((
1628                         start_point,
1629                         if has_nested {
1630                             // In this case, `start_snippet` must equal '{'.
1631                             format!("{}{}, ", start_snippet, import_snippet)
1632                         } else {
1633                             // In this case, add a `{`, then the moved import, then whatever
1634                             // was there before.
1635                             format!("{{{}, {}", import_snippet, start_snippet)
1636                         },
1637                     ));
1638                 }
1639
1640                 // Add a `};` to the end if nested, matching the `{` added at the start.
1641                 if !has_nested {
1642                     corrections.push((source_map.end_point(after_crate_name), "};".to_string()));
1643                 }
1644             }
1645
1646             let suggestion = Some((
1647                 corrections,
1648                 String::from("a macro with this name exists at the root of the crate"),
1649                 Applicability::MaybeIncorrect,
1650             ));
1651             let note = vec![
1652                 "this could be because a macro annotated with `#[macro_export]` will be exported \
1653                  at the root of the crate instead of the module where it is defined"
1654                     .to_string(),
1655             ];
1656             Some((suggestion, note))
1657         } else {
1658             None
1659         }
1660     }
1661 }
1662
1663 /// Given a `binding_span` of a binding within a use statement:
1664 ///
1665 /// ```
1666 /// use foo::{a, b, c};
1667 ///              ^
1668 /// ```
1669 ///
1670 /// then return the span until the next binding or the end of the statement:
1671 ///
1672 /// ```
1673 /// use foo::{a, b, c};
1674 ///              ^^^
1675 /// ```
1676 pub(crate) fn find_span_of_binding_until_next_binding(
1677     sess: &Session,
1678     binding_span: Span,
1679     use_span: Span,
1680 ) -> (bool, Span) {
1681     let source_map = sess.source_map();
1682
1683     // Find the span of everything after the binding.
1684     //   ie. `a, e};` or `a};`
1685     let binding_until_end = binding_span.with_hi(use_span.hi());
1686
1687     // Find everything after the binding but not including the binding.
1688     //   ie. `, e};` or `};`
1689     let after_binding_until_end = binding_until_end.with_lo(binding_span.hi());
1690
1691     // Keep characters in the span until we encounter something that isn't a comma or
1692     // whitespace.
1693     //   ie. `, ` or ``.
1694     //
1695     // Also note whether a closing brace character was encountered. If there
1696     // was, then later go backwards to remove any trailing commas that are left.
1697     let mut found_closing_brace = false;
1698     let after_binding_until_next_binding =
1699         source_map.span_take_while(after_binding_until_end, |&ch| {
1700             if ch == '}' {
1701                 found_closing_brace = true;
1702             }
1703             ch == ' ' || ch == ','
1704         });
1705
1706     // Combine the two spans.
1707     //   ie. `a, ` or `a`.
1708     //
1709     // Removing these would leave `issue_52891::{d, e};` or `issue_52891::{d, e, };`
1710     let span = binding_span.with_hi(after_binding_until_next_binding.hi());
1711
1712     (found_closing_brace, span)
1713 }
1714
1715 /// Given a `binding_span`, return the span through to the comma or opening brace of the previous
1716 /// binding.
1717 ///
1718 /// ```
1719 /// use foo::a::{a, b, c};
1720 ///               ^^--- binding span
1721 ///               |
1722 ///               returned span
1723 ///
1724 /// use foo::{a, b, c};
1725 ///           --- binding span
1726 /// ```
1727 pub(crate) fn extend_span_to_previous_binding(sess: &Session, binding_span: Span) -> Option<Span> {
1728     let source_map = sess.source_map();
1729
1730     // `prev_source` will contain all of the source that came before the span.
1731     // Then split based on a command and take the first (ie. closest to our span)
1732     // snippet. In the example, this is a space.
1733     let prev_source = source_map.span_to_prev_source(binding_span).ok()?;
1734
1735     let prev_comma = prev_source.rsplit(',').collect::<Vec<_>>();
1736     let prev_starting_brace = prev_source.rsplit('{').collect::<Vec<_>>();
1737     if prev_comma.len() <= 1 || prev_starting_brace.len() <= 1 {
1738         return None;
1739     }
1740
1741     let prev_comma = prev_comma.first().unwrap();
1742     let prev_starting_brace = prev_starting_brace.first().unwrap();
1743
1744     // If the amount of source code before the comma is greater than
1745     // the amount of source code before the starting brace then we've only
1746     // got one item in the nested item (eg. `issue_52891::{self}`).
1747     if prev_comma.len() > prev_starting_brace.len() {
1748         return None;
1749     }
1750
1751     Some(binding_span.with_lo(BytePos(
1752         // Take away the number of bytes for the characters we've found and an
1753         // extra for the comma.
1754         binding_span.lo().0 - (prev_comma.as_bytes().len() as u32) - 1,
1755     )))
1756 }
1757
1758 /// Given a `use_span` of a binding within a use statement, returns the highlighted span and if
1759 /// it is a nested use tree.
1760 ///
1761 /// ```
1762 /// use foo::a::{b, c};
1763 ///          ^^^^^^^^^^ // false
1764 ///
1765 /// use foo::{a, b, c};
1766 ///          ^^^^^^^^^^ // true
1767 ///
1768 /// use foo::{a, b::{c, d}};
1769 ///          ^^^^^^^^^^^^^^^ // true
1770 /// ```
1771 fn find_span_immediately_after_crate_name(
1772     sess: &Session,
1773     module_name: Symbol,
1774     use_span: Span,
1775 ) -> (bool, Span) {
1776     debug!(
1777         "find_span_immediately_after_crate_name: module_name={:?} use_span={:?}",
1778         module_name, use_span
1779     );
1780     let source_map = sess.source_map();
1781
1782     // Using `use issue_59764::foo::{baz, makro};` as an example throughout..
1783     let mut num_colons = 0;
1784     // Find second colon.. `use issue_59764:`
1785     let until_second_colon = source_map.span_take_while(use_span, |c| {
1786         if *c == ':' {
1787             num_colons += 1;
1788         }
1789         !matches!(c, ':' if num_colons == 2)
1790     });
1791     // Find everything after the second colon.. `foo::{baz, makro};`
1792     let from_second_colon = use_span.with_lo(until_second_colon.hi() + BytePos(1));
1793
1794     let mut found_a_non_whitespace_character = false;
1795     // Find the first non-whitespace character in `from_second_colon`.. `f`
1796     let after_second_colon = source_map.span_take_while(from_second_colon, |c| {
1797         if found_a_non_whitespace_character {
1798             return false;
1799         }
1800         if !c.is_whitespace() {
1801             found_a_non_whitespace_character = true;
1802         }
1803         true
1804     });
1805
1806     // Find the first `{` in from_second_colon.. `foo::{`
1807     let next_left_bracket = source_map.span_through_char(from_second_colon, '{');
1808
1809     (next_left_bracket == after_second_colon, from_second_colon)
1810 }
1811
1812 /// When an entity with a given name is not available in scope, we search for
1813 /// entities with that name in all crates. This method allows outputting the
1814 /// results of this search in a programmer-friendly way
1815 crate fn show_candidates(
1816     definitions: &rustc_hir::definitions::Definitions,
1817     session: &Session,
1818     err: &mut Diagnostic,
1819     // This is `None` if all placement locations are inside expansions
1820     use_placement_span: Option<Span>,
1821     candidates: &[ImportSuggestion],
1822     instead: bool,
1823     found_use: bool,
1824 ) {
1825     if candidates.is_empty() {
1826         return;
1827     }
1828
1829     let mut accessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> =
1830         Vec::new();
1831     let mut inaccessible_path_strings: Vec<(String, &str, Option<DefId>, &Option<String>)> =
1832         Vec::new();
1833
1834     candidates.iter().for_each(|c| {
1835         (if c.accessible { &mut accessible_path_strings } else { &mut inaccessible_path_strings })
1836             .push((path_names_to_string(&c.path), c.descr, c.did, &c.note))
1837     });
1838
1839     // we want consistent results across executions, but candidates are produced
1840     // by iterating through a hash map, so make sure they are ordered:
1841     for path_strings in [&mut accessible_path_strings, &mut inaccessible_path_strings] {
1842         path_strings.sort_by(|a, b| a.0.cmp(&b.0));
1843         let core_path_strings =
1844             path_strings.drain_filter(|p| p.0.starts_with("core::")).collect::<Vec<_>>();
1845         path_strings.extend(core_path_strings);
1846         path_strings.dedup_by(|a, b| a.0 == b.0);
1847     }
1848
1849     if !accessible_path_strings.is_empty() {
1850         let (determiner, kind) = if accessible_path_strings.len() == 1 {
1851             ("this", accessible_path_strings[0].1)
1852         } else {
1853             ("one of these", "items")
1854         };
1855
1856         let instead = if instead { " instead" } else { "" };
1857         let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
1858
1859         for note in accessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
1860             err.note(note);
1861         }
1862
1863         if let Some(span) = use_placement_span {
1864             for candidate in &mut accessible_path_strings {
1865                 // produce an additional newline to separate the new use statement
1866                 // from the directly following item.
1867                 let additional_newline = if found_use { "" } else { "\n" };
1868                 candidate.0 = format!("use {};\n{}", &candidate.0, additional_newline);
1869             }
1870
1871             err.span_suggestions(
1872                 span,
1873                 &msg,
1874                 accessible_path_strings.into_iter().map(|a| a.0),
1875                 Applicability::Unspecified,
1876             );
1877         } else {
1878             msg.push(':');
1879
1880             for candidate in accessible_path_strings {
1881                 msg.push('\n');
1882                 msg.push_str(&candidate.0);
1883             }
1884
1885             err.note(&msg);
1886         }
1887     } else {
1888         assert!(!inaccessible_path_strings.is_empty());
1889
1890         if inaccessible_path_strings.len() == 1 {
1891             let (name, descr, def_id, note) = &inaccessible_path_strings[0];
1892             let msg = format!("{} `{}` exists but is inaccessible", descr, name);
1893
1894             if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
1895                 let span = definitions.def_span(local_def_id);
1896                 let span = session.source_map().guess_head_span(span);
1897                 let mut multi_span = MultiSpan::from_span(span);
1898                 multi_span.push_span_label(span, "not accessible".to_string());
1899                 err.span_note(multi_span, &msg);
1900             } else {
1901                 err.note(&msg);
1902             }
1903             if let Some(note) = (*note).as_deref() {
1904                 err.note(note);
1905             }
1906         } else {
1907             let (_, descr_first, _, _) = &inaccessible_path_strings[0];
1908             let descr = if inaccessible_path_strings
1909                 .iter()
1910                 .skip(1)
1911                 .all(|(_, descr, _, _)| descr == descr_first)
1912             {
1913                 descr_first.to_string()
1914             } else {
1915                 "item".to_string()
1916             };
1917
1918             let mut msg = format!("these {}s exist but are inaccessible", descr);
1919             let mut has_colon = false;
1920
1921             let mut spans = Vec::new();
1922             for (name, _, def_id, _) in &inaccessible_path_strings {
1923                 if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
1924                     let span = definitions.def_span(local_def_id);
1925                     let span = session.source_map().guess_head_span(span);
1926                     spans.push((name, span));
1927                 } else {
1928                     if !has_colon {
1929                         msg.push(':');
1930                         has_colon = true;
1931                     }
1932                     msg.push('\n');
1933                     msg.push_str(name);
1934                 }
1935             }
1936
1937             let mut multi_span = MultiSpan::from_spans(spans.iter().map(|(_, sp)| *sp).collect());
1938             for (name, span) in spans {
1939                 multi_span.push_span_label(span, format!("`{}`: not accessible", name));
1940             }
1941
1942             for note in inaccessible_path_strings.iter().flat_map(|cand| cand.3.as_ref()) {
1943                 err.note(note);
1944             }
1945
1946             err.span_note(multi_span, &msg);
1947         }
1948     }
1949 }