src/librustc_resolve/resolve_imports.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use self::ImportDirectiveSubclass::*;
  12
  13 use DefModifiers;
  14 use Module;
  15 use Namespace::{self, TypeNS, ValueNS};
  16 use NameBinding;
  17 use ResolveResult;
  18 use ResolveResult::*;
  19 use Resolver;
  20 use UseLexicalScopeFlag;
  21 use {names_to_string, module_to_string};
  22 use {resolve_error, ResolutionError};
  23
  24 use build_reduced_graph;
  25
  26 use rustc::lint;
  27 use rustc::middle::def::*;
  28 use rustc::middle::def_id::DefId;
  29 use rustc::middle::privacy::*;
  30
  31 use syntax::ast::{NodeId, Name};
  32 use syntax::attr::AttrMetaMethods;
  33 use syntax::codemap::Span;
  34 use syntax::util::lev_distance::find_best_match_for_name;
  35
  36 use std::mem::replace;
  37
  38 /// Contains data for specific types of import directives.
  39 #[derive(Copy, Clone,Debug)]
  40 pub enum ImportDirectiveSubclass {
  41     SingleImport(Name /* target */, Name /* source */),
  42     GlobImport,
  43 }
  44
  45 /// Whether an import can be shadowed by another import.
  46 #[derive(Debug,PartialEq,Clone,Copy)]
  47 pub enum Shadowable {
  48     Always,
  49     Never,
  50 }
  51
  52 /// One import directive.
  53 #[derive(Debug)]
  54 pub struct ImportDirective {
  55     pub module_path: Vec<Name>,
  56     pub subclass: ImportDirectiveSubclass,
  57     pub span: Span,
  58     pub id: NodeId,
  59     pub is_public: bool, // see note in ImportResolutionPerNamespace about how to use this
  60     pub shadowable: Shadowable,
  61 }
  62
  63 impl ImportDirective {
  64     pub fn new(module_path: Vec<Name>,
  65                subclass: ImportDirectiveSubclass,
  66                span: Span,
  67                id: NodeId,
  68                is_public: bool,
  69                shadowable: Shadowable)
  70                -> ImportDirective {
  71         ImportDirective {
  72             module_path: module_path,
  73             subclass: subclass,
  74             span: span,
  75             id: id,
  76             is_public: is_public,
  77             shadowable: shadowable,
  78         }
  79     }
  80 }
  81
  82 /// The item that an import resolves to.
  83 #[derive(Clone,Debug)]
  84 pub struct Target<'a> {
  85     pub target_module: Module<'a>,
  86     pub binding: NameBinding<'a>,
  87     pub shadowable: Shadowable,
  88 }
  89
  90 impl<'a> Target<'a> {
  91     pub fn new(target_module: Module<'a>, binding: NameBinding<'a>, shadowable: Shadowable)
  92                -> Self {
  93         Target {
  94             target_module: target_module,
  95             binding: binding,
  96             shadowable: shadowable,
  97         }
  98     }
  99 }
 100
 101 #[derive(Debug)]
 102 /// An ImportResolution records what we know about an imported name in a given namespace.
 103 /// More specifically, it records the number of unresolved `use` directives that import the name,
 104 /// the `use` directive importing the name in the namespace, and the `NameBinding` to which the
 105 /// name in the namespace resolves (if applicable).
 106 /// Different `use` directives may import the same name in different namespaces.
 107 pub struct ImportResolution<'a> {
 108     // When outstanding_references reaches zero, outside modules can count on the targets being
 109     // correct. Before then, all bets are off; future `use` directives could override the name.
 110     // Since shadowing is forbidden, the only way outstanding_references > 1 in a legal program
 111     // is if the name is imported by exactly two `use` directives, one of which resolves to a
 112     // value and the other of which resolves to a type.
 113     pub outstanding_references: usize,
 114
 115     /// Whether this resolution came from a `use` or a `pub use`.
 116     pub is_public: bool,
 117
 118     /// Resolution of the name in the namespace
 119     pub target: Option<Target<'a>>,
 120
 121     /// The source node of the `use` directive
 122     pub id: NodeId,
 123 }
 124
 125 impl<'a> ImportResolution<'a> {
 126     pub fn new(id: NodeId, is_public: bool) -> Self {
 127         ImportResolution {
 128             outstanding_references: 0,
 129             id: id,
 130             target: None,
 131             is_public: is_public,
 132         }
 133     }
 134
 135     pub fn shadowable(&self) -> Shadowable {
 136         match self.target {
 137             Some(ref target) => target.shadowable,
 138             None => Shadowable::Always,
 139         }
 140     }
 141 }
 142
 143 struct ImportResolvingError {
 144     span: Span,
 145     path: String,
 146     help: String,
 147 }
 148
 149 struct ImportResolver<'a, 'b: 'a, 'tcx: 'b> {
 150     resolver: &'a mut Resolver<'b, 'tcx>,
 151 }
 152
 153 impl<'a, 'b:'a, 'tcx:'b> ImportResolver<'a, 'b, 'tcx> {
 154     // Import resolution
 155     //
 156     // This is a fixed-point algorithm. We resolve imports until our efforts
 157     // are stymied by an unresolved import; then we bail out of the current
 158     // module and continue. We terminate successfully once no more imports
 159     // remain or unsuccessfully when no forward progress in resolving imports
 160     // is made.
 161
 162     /// Resolves all imports for the crate. This method performs the fixed-
 163     /// point iteration.
 164     fn resolve_imports(&mut self) {
 165         let mut i = 0;
 166         let mut prev_unresolved_imports = 0;
 167         loop {
 168             debug!("(resolving imports) iteration {}, {} imports left",
 169                    i,
 170                    self.resolver.unresolved_imports);
 171
 172             let module_root = self.resolver.graph_root;
 173             let errors = self.resolve_imports_for_module_subtree(module_root);
 174
 175             if self.resolver.unresolved_imports == 0 {
 176                 debug!("(resolving imports) success");
 177                 break;
 178             }
 179
 180             if self.resolver.unresolved_imports == prev_unresolved_imports {
 181                 // resolving failed
 182                 if errors.len() > 0 {
 183                     for e in errors {
 184                         resolve_error(self.resolver,
 185                                       e.span,
 186                                       ResolutionError::UnresolvedImport(Some((&e.path, &e.help))));
 187                     }
 188                 } else {
 189                     // Report unresolved imports only if no hard error was already reported
 190                     // to avoid generating multiple errors on the same import.
 191                     // Imports that are still indeterminate at this point are actually blocked
 192                     // by errored imports, so there is no point reporting them.
 193                     self.resolver.report_unresolved_imports(module_root);
 194                 }
 195                 break;
 196             }
 197
 198             i += 1;
 199             prev_unresolved_imports = self.resolver.unresolved_imports;
 200         }
 201     }
 202
 203     /// Attempts to resolve imports for the given module and all of its
 204     /// submodules.
 205     fn resolve_imports_for_module_subtree(&mut self,
 206                                           module_: Module<'b>)
 207                                           -> Vec<ImportResolvingError> {
 208         let mut errors = Vec::new();
 209         debug!("(resolving imports for module subtree) resolving {}",
 210                module_to_string(&*module_));
 211         let orig_module = replace(&mut self.resolver.current_module, module_);
 212         errors.extend(self.resolve_imports_for_module(module_));
 213         self.resolver.current_module = orig_module;
 214
 215         build_reduced_graph::populate_module_if_necessary(self.resolver, &module_);
 216         for (_, child_node) in module_.children.borrow().iter() {
 217             match child_node.module() {
 218                 None => {
 219                     // Nothing to do.
 220                 }
 221                 Some(child_module) => {
 222                     errors.extend(self.resolve_imports_for_module_subtree(child_module));
 223                 }
 224             }
 225         }
 226
 227         for (_, child_module) in module_.anonymous_children.borrow().iter() {
 228             errors.extend(self.resolve_imports_for_module_subtree(child_module));
 229         }
 230
 231         errors
 232     }
 233
 234     /// Attempts to resolve imports for the given module only.
 235     fn resolve_imports_for_module(&mut self, module: Module<'b>) -> Vec<ImportResolvingError> {
 236         let mut errors = Vec::new();
 237
 238         if module.all_imports_resolved() {
 239             debug!("(resolving imports for module) all imports resolved for {}",
 240                    module_to_string(&*module));
 241             return errors;
 242         }
 243
 244         let mut imports = module.imports.borrow_mut();
 245         let import_count = imports.len();
 246         let mut indeterminate_imports = Vec::new();
 247         while module.resolved_import_count.get() + indeterminate_imports.len() < import_count {
 248             let import_index = module.resolved_import_count.get();
 249             match self.resolve_import_for_module(module, &imports[import_index]) {
 250                 ResolveResult::Failed(err) => {
 251                     let import_directive = &imports[import_index];
 252                     let (span, help) = match err {
 253                         Some((span, msg)) => (span, format!(". {}", msg)),
 254                         None => (import_directive.span, String::new()),
 255                     };
 256                     errors.push(ImportResolvingError {
 257                         span: span,
 258                         path: import_path_to_string(&import_directive.module_path,
 259                                                     import_directive.subclass),
 260                         help: help,
 261                     });
 262                 }
 263                 ResolveResult::Indeterminate => {}
 264                 ResolveResult::Success(()) => {
 265                     // count success
 266                     module.resolved_import_count
 267                           .set(module.resolved_import_count.get() + 1);
 268                     continue;
 269                 }
 270             }
 271             // This resolution was not successful, keep it for later
 272             indeterminate_imports.push(imports.swap_remove(import_index));
 273
 274         }
 275
 276         imports.extend(indeterminate_imports);
 277
 278         errors
 279     }
 280
 281     /// Attempts to resolve the given import. The return value indicates
 282     /// failure if we're certain the name does not exist, indeterminate if we
 283     /// don't know whether the name exists at the moment due to other
 284     /// currently-unresolved imports, or success if we know the name exists.
 285     /// If successful, the resolved bindings are written into the module.
 286     fn resolve_import_for_module(&mut self,
 287                                  module_: Module<'b>,
 288                                  import_directive: &ImportDirective)
 289                                  -> ResolveResult<()> {
 290         let mut resolution_result = ResolveResult::Failed(None);
 291         let module_path = &import_directive.module_path;
 292
 293         debug!("(resolving import for module) resolving import `{}::...` in `{}`",
 294                names_to_string(&module_path[..]),
 295                module_to_string(&*module_));
 296
 297         // First, resolve the module path for the directive, if necessary.
 298         let container = if module_path.is_empty() {
 299             // Use the crate root.
 300             Some((self.resolver.graph_root, LastMod(AllPublic)))
 301         } else {
 302             match self.resolver.resolve_module_path(module_,
 303                                                     &module_path[..],
 304                                                     UseLexicalScopeFlag::DontUseLexicalScope,
 305                                                     import_directive.span) {
 306                 ResolveResult::Failed(err) => {
 307                     resolution_result = ResolveResult::Failed(err);
 308                     None
 309                 }
 310                 ResolveResult::Indeterminate => {
 311                     resolution_result = ResolveResult::Indeterminate;
 312                     None
 313                 }
 314                 ResolveResult::Success(container) => Some(container),
 315             }
 316         };
 317
 318         match container {
 319             None => {}
 320             Some((containing_module, lp)) => {
 321                 // We found the module that the target is contained
 322                 // within. Attempt to resolve the import within it.
 323
 324                 match import_directive.subclass {
 325                     SingleImport(target, source) => {
 326                         resolution_result = self.resolve_single_import(&module_,
 327                                                                        containing_module,
 328                                                                        target,
 329                                                                        source,
 330                                                                        import_directive,
 331                                                                        lp);
 332                     }
 333                     GlobImport => {
 334                         resolution_result = self.resolve_glob_import(&module_,
 335                                                                      containing_module,
 336                                                                      import_directive,
 337                                                                      lp);
 338                     }
 339                 }
 340             }
 341         }
 342
 343         // Decrement the count of unresolved imports.
 344         match resolution_result {
 345             ResolveResult::Success(()) => {
 346                 assert!(self.resolver.unresolved_imports >= 1);
 347                 self.resolver.unresolved_imports -= 1;
 348             }
 349             _ => {
 350                 // Nothing to do here; just return the error.
 351             }
 352         }
 353
 354         // Decrement the count of unresolved globs if necessary. But only if
 355         // the resolution result is a success -- other cases will
 356         // be handled by the main loop.
 357
 358         if resolution_result.success() {
 359             match import_directive.subclass {
 360                 GlobImport => {
 361                     module_.dec_glob_count();
 362                     if import_directive.is_public {
 363                         module_.dec_pub_glob_count();
 364                     }
 365                 }
 366                 SingleImport(..) => {
 367                     // Ignore.
 368                 }
 369             }
 370             if import_directive.is_public {
 371                 module_.dec_pub_count();
 372             }
 373         }
 374
 375         return resolution_result;
 376     }
 377
 378     fn resolve_imported_name_in_module(&mut self,
 379                                        module: Module<'b>, // Module containing the name
 380                                        name: Name,
 381                                        ns: Namespace,
 382                                        importing_module: Module<'b>) // Module importing the name
 383                                        -> ResolveResult<(Module<'b>, NameBinding<'b>)> {
 384         match module.import_resolutions.borrow().get(&(name, ns)) {
 385             // The containing module definitely doesn't have an exported import with the
 386             // name in question. We can therefore accurately report that names are unbound.
 387             None => Failed(None),
 388
 389             // The name is an import which has been fully resolved, so we just follow it.
 390             Some(resolution) if resolution.outstanding_references == 0 => {
 391                 // Import resolutions must be declared with "pub" in order to be exported.
 392                 if !resolution.is_public {
 393                     return Failed(None);
 394                 }
 395
 396                 let target = resolution.target.clone();
 397                 if let Some(Target { target_module, binding, shadowable: _ }) = target {
 398                     // track used imports and extern crates as well
 399                     self.resolver.used_imports.insert((resolution.id, ns));
 400                     self.resolver.record_import_use(resolution.id, name);
 401                     if let Some(DefId { krate, .. }) = target_module.def_id() {
 402                         self.resolver.used_crates.insert(krate);
 403                     }
 404                     Success((target_module, binding))
 405                 } else {
 406                     Failed(None)
 407                 }
 408             }
 409
 410             // If module is the same module whose import we are resolving and
 411             // it has an unresolved import with the same name as `name`, then the user
 412             // is actually trying to import an item that is declared in the same scope
 413             //
 414             // e.g
 415             // use self::submodule;
 416             // pub mod submodule;
 417             //
 418             // In this case we continue as if we resolved the import and let the
 419             // check_for_conflicts_between_imports_and_items call below handle the conflict
 420             Some(_) => match (importing_module.def_id(), module.def_id()) {
 421                 (Some(id1), Some(id2)) if id1 == id2 => Failed(None),
 422                 _ => Indeterminate,
 423             },
 424         }
 425     }
 426
 427     fn resolve_single_import(&mut self,
 428                              module_: Module<'b>,
 429                              target_module: Module<'b>,
 430                              target: Name,
 431                              source: Name,
 432                              directive: &ImportDirective,
 433                              lp: LastPrivate)
 434                              -> ResolveResult<()> {
 435         debug!("(resolving single import) resolving `{}` = `{}::{}` from `{}` id {}, last \
 436                 private {:?}",
 437                target,
 438                module_to_string(&*target_module),
 439                source,
 440                module_to_string(module_),
 441                directive.id,
 442                lp);
 443
 444         let lp = match lp {
 445             LastMod(lp) => lp,
 446             LastImport {..} => {
 447                 self.resolver
 448                     .session
 449                     .span_bug(directive.span, "not expecting Import here, must be LastMod")
 450             }
 451         };
 452
 453         // We need to resolve both namespaces for this to succeed.
 454         let mut value_result = Indeterminate;
 455         let mut type_result = Indeterminate;
 456         let mut lev_suggestion = "".to_owned();
 457
 458         // Search for direct children of the containing module.
 459         build_reduced_graph::populate_module_if_necessary(self.resolver, &target_module);
 460
 461         // pub_err makes sure we don't give the same error twice.
 462         let mut pub_err = false;
 463
 464         if let Some(name_binding) = target_module.get_child(source, ValueNS) {
 465             debug!("(resolving single import) found value binding");
 466             value_result = Success((target_module, name_binding.clone()));
 467             if directive.is_public && !name_binding.is_public() {
 468                 let msg = format!("`{}` is private, and cannot be reexported", source);
 469                 let note_msg = format!("Consider marking `{}` as `pub` in the imported module",
 470                                         source);
 471                 struct_span_err!(self.resolver.session, directive.span, E0364, "{}", &msg)
 472                     .span_note(directive.span, &note_msg)
 473                     .emit();
 474                 pub_err = true;
 475             }
 476         }
 477
 478         if let Some(name_binding) = target_module.get_child(source, TypeNS) {
 479             debug!("(resolving single import) found type binding");
 480             type_result = Success((target_module, name_binding.clone()));
 481             if !pub_err && directive.is_public {
 482                 if !name_binding.is_public() {
 483                     let msg = format!("`{}` is private, and cannot be reexported", source);
 484                     let note_msg =
 485                         format!("Consider declaring type or module `{}` with `pub`", source);
 486                     struct_span_err!(self.resolver.session, directive.span, E0365, "{}", &msg)
 487                         .span_note(directive.span, &note_msg)
 488                         .emit();
 489                 } else if name_binding.defined_with(DefModifiers::PRIVATE_VARIANT) {
 490                     let msg = format!("variant `{}` is private, and cannot be reexported \
 491                                        (error E0364), consider declaring its enum as `pub`",
 492                                        source);
 493                     self.resolver.session.add_lint(lint::builtin::PRIVATE_IN_PUBLIC,
 494                                                    directive.id,
 495                                                    directive.span,
 496                                                    msg);
 497                 }
 498             }
 499         }
 500
 501         if let (&Indeterminate, &Indeterminate) = (&value_result, &type_result) {
 502             let names = target_module.children.borrow();
 503             let names = names.keys().map(|&(ref name, _)| name);
 504             if let Some(name) = find_best_match_for_name(names, &source.as_str(), None) {
 505                 lev_suggestion = format!(". Did you mean to use `{}`?", name);
 506             }
 507         }
 508
 509         match (&value_result, &type_result) {
 510             // If there is an unresolved glob at this point in the containing module, bail out.
 511             // We don't know enough to be able to resolve this import.
 512             (&Indeterminate, _) | (_, &Indeterminate) if target_module.pub_glob_count.get() > 0 =>
 513                 return Indeterminate,
 514             _ => ()
 515         }
 516
 517         let mut value_used_reexport = false;
 518         if let Indeterminate = value_result {
 519             value_result =
 520                 self.resolve_imported_name_in_module(&target_module, source, ValueNS, module_);
 521             value_used_reexport = match value_result { Success(_) => true, _ => false };
 522         }
 523
 524         let mut type_used_reexport = false;
 525         if let Indeterminate = type_result {
 526             type_result =
 527                 self.resolve_imported_name_in_module(&target_module, source, TypeNS, module_);
 528             type_used_reexport = match type_result { Success(_) => true, _ => false };
 529         }
 530
 531         match (&value_result, &type_result) {
 532             (&Indeterminate, _) | (_, &Indeterminate) => return Indeterminate,
 533             (&Failed(_), &Failed(_)) => {
 534                 if lev_suggestion.is_empty() {  // skip if we already have a suggestion
 535                     let names = target_module.import_resolutions.borrow();
 536                     let names = names.keys().map(|&(ref name, _)| name);
 537                     if let Some(name) = find_best_match_for_name(names,
 538                                                                  &source.as_str(),
 539                                                                  None) {
 540                         lev_suggestion =
 541                             format!(". Did you mean to use the re-exported import `{}`?",
 542                                     name);
 543                     }
 544                 }
 545             }
 546             _ => (),
 547         }
 548
 549         let mut value_used_public = false;
 550         let mut type_used_public = false;
 551
 552         // If we didn't find a result in the type namespace, search the
 553         // external modules.
 554         match type_result {
 555             Success(..) => {}
 556             _ => {
 557                 match target_module.external_module_children.borrow_mut().get(&source).cloned() {
 558                     None => {} // Continue.
 559                     Some(module) => {
 560                         debug!("(resolving single import) found external module");
 561                         // track the module as used.
 562                         match module.def_id() {
 563                             Some(DefId{krate: kid, ..}) => {
 564                                 self.resolver.used_crates.insert(kid);
 565                             }
 566                             _ => {}
 567                         }
 568                         let name_binding = NameBinding::create_from_module(module, None);
 569                         type_result = Success((target_module, name_binding));
 570                         type_used_public = true;
 571                     }
 572                 }
 573             }
 574         }
 575
 576         // We've successfully resolved the import. Write the results in.
 577         let mut import_resolutions = module_.import_resolutions.borrow_mut();
 578
 579         {
 580             let mut check_and_write_import = |namespace, result, used_public: &mut bool| {
 581                 let result: &ResolveResult<(Module<'b>, NameBinding)> = result;
 582
 583                 let import_resolution = import_resolutions.get_mut(&(target, namespace)).unwrap();
 584                 let namespace_name = match namespace {
 585                     TypeNS => "type",
 586                     ValueNS => "value",
 587                 };
 588
 589                 match *result {
 590                     Success((ref target_module, ref name_binding)) => {
 591                         debug!("(resolving single import) found {:?} target: {:?}",
 592                                namespace_name,
 593                                name_binding.def());
 594                         self.check_for_conflicting_import(&import_resolution,
 595                                                           directive.span,
 596                                                           target,
 597                                                           namespace);
 598
 599                         self.check_that_import_is_importable(&name_binding,
 600                                                              directive.span,
 601                                                              target);
 602
 603                         import_resolution.target = Some(Target::new(target_module,
 604                                                                     name_binding.clone(),
 605                                                                     directive.shadowable));
 606                         import_resolution.id = directive.id;
 607                         import_resolution.is_public = directive.is_public;
 608
 609                         self.add_export(module_, target, &import_resolution);
 610                         *used_public = name_binding.is_public();
 611                     }
 612                     Failed(_) => {
 613                         // Continue.
 614                     }
 615                     Indeterminate => {
 616                         panic!("{:?} result should be known at this point", namespace_name);
 617                     }
 618                 }
 619
 620                 self.check_for_conflicts_between_imports_and_items(module_,
 621                                                                    import_resolution,
 622                                                                    directive.span,
 623                                                                    (target, namespace));
 624
 625             };
 626             check_and_write_import(ValueNS, &value_result, &mut value_used_public);
 627             check_and_write_import(TypeNS, &type_result, &mut type_used_public);
 628         }
 629
 630         if let (&Failed(_), &Failed(_)) = (&value_result, &type_result) {
 631             let msg = format!("There is no `{}` in `{}`{}",
 632                               source,
 633                               module_to_string(&target_module), lev_suggestion);
 634             return ResolveResult::Failed(Some((directive.span, msg)));
 635         }
 636         let value_used_public = value_used_reexport || value_used_public;
 637         let type_used_public = type_used_reexport || type_used_public;
 638
 639         let value_def_and_priv = {
 640             let import_resolution_value = import_resolutions.get_mut(&(target, ValueNS)).unwrap();
 641             assert!(import_resolution_value.outstanding_references >= 1);
 642             import_resolution_value.outstanding_references -= 1;
 643
 644             // Record what this import resolves to for later uses in documentation,
 645             // this may resolve to either a value or a type, but for documentation
 646             // purposes it's good enough to just favor one over the other.
 647             import_resolution_value.target.as_ref().map(|target| {
 648                 let def = target.binding.def().unwrap();
 649                 (def,
 650                  if value_used_public {
 651                     lp
 652                 } else {
 653                     DependsOn(def.def_id())
 654                 })
 655             })
 656         };
 657
 658         let type_def_and_priv = {
 659             let import_resolution_type = import_resolutions.get_mut(&(target, TypeNS)).unwrap();
 660             assert!(import_resolution_type.outstanding_references >= 1);
 661             import_resolution_type.outstanding_references -= 1;
 662
 663             import_resolution_type.target.as_ref().map(|target| {
 664                 let def = target.binding.def().unwrap();
 665                 (def,
 666                 if type_used_public {
 667                     lp
 668                 } else {
 669                     DependsOn(def.def_id())
 670                 })
 671             })
 672         };
 673
 674         let import_lp = LastImport {
 675             value_priv: value_def_and_priv.map(|(_, p)| p),
 676             value_used: Used,
 677             type_priv: type_def_and_priv.map(|(_, p)| p),
 678             type_used: Used,
 679         };
 680
 681         if let Some((def, _)) = value_def_and_priv {
 682             self.resolver.def_map.borrow_mut().insert(directive.id,
 683                                                       PathResolution {
 684                                                           base_def: def,
 685                                                           last_private: import_lp,
 686                                                           depth: 0,
 687                                                       });
 688         }
 689         if let Some((def, _)) = type_def_and_priv {
 690             self.resolver.def_map.borrow_mut().insert(directive.id,
 691                                                       PathResolution {
 692                                                           base_def: def,
 693                                                           last_private: import_lp,
 694                                                           depth: 0,
 695                                                       });
 696         }
 697
 698         debug!("(resolving single import) successfully resolved import");
 699         return ResolveResult::Success(());
 700     }
 701
 702     // Resolves a glob import. Note that this function cannot fail; it either
 703     // succeeds or bails out (as importing * from an empty module or a module
 704     // that exports nothing is valid). target_module is the module we are
 705     // actually importing, i.e., `foo` in `use foo::*`.
 706     fn resolve_glob_import(&mut self,
 707                            module_: Module<'b>,
 708                            target_module: Module<'b>,
 709                            import_directive: &ImportDirective,
 710                            lp: LastPrivate)
 711                            -> ResolveResult<()> {
 712         let id = import_directive.id;
 713         let is_public = import_directive.is_public;
 714
 715         // This function works in a highly imperative manner; it eagerly adds
 716         // everything it can to the list of import resolutions of the module
 717         // node.
 718         debug!("(resolving glob import) resolving glob import {}", id);
 719
 720         // We must bail out if the node has unresolved imports of any kind
 721         // (including globs).
 722         if (*target_module).pub_count.get() > 0 {
 723             debug!("(resolving glob import) target module has unresolved pub imports; bailing out");
 724             return ResolveResult::Indeterminate;
 725         }
 726
 727         // Add all resolved imports from the containing module.
 728         let import_resolutions = target_module.import_resolutions.borrow();
 729
 730         if module_.import_resolutions.borrow_state() != ::std::cell::BorrowState::Unused {
 731             // In this case, target_module == module_
 732             // This means we are trying to glob import a module into itself,
 733             // and it is a no-go
 734             debug!("(resolving glob imports) target module is current module; giving up");
 735             return ResolveResult::Failed(Some((import_directive.span,
 736                                                "Cannot glob-import a module into itself.".into())));
 737         }
 738
 739         for (&(name, ns), target_import_resolution) in import_resolutions.iter() {
 740             debug!("(resolving glob import) writing module resolution {} into `{}`",
 741                    name,
 742                    module_to_string(module_));
 743
 744             // Here we merge two import resolutions.
 745             let mut import_resolutions = module_.import_resolutions.borrow_mut();
 746             let mut dest_import_resolution =
 747                 import_resolutions.entry((name, ns))
 748                                   .or_insert_with(|| ImportResolution::new(id, is_public));
 749
 750             match target_import_resolution.target {
 751                 Some(ref target) if target_import_resolution.is_public => {
 752                     self.check_for_conflicting_import(&dest_import_resolution,
 753                                                       import_directive.span,
 754                                                       name,
 755                                                       ns);
 756                     dest_import_resolution.id = id;
 757                     dest_import_resolution.is_public = is_public;
 758                     dest_import_resolution.target = Some(target.clone());
 759                     self.add_export(module_, name, &dest_import_resolution);
 760                 }
 761                 _ => {}
 762             }
 763         }
 764
 765         // Add all children from the containing module.
 766         build_reduced_graph::populate_module_if_necessary(self.resolver, &target_module);
 767
 768         for (&name, name_binding) in target_module.children.borrow().iter() {
 769             self.merge_import_resolution(module_,
 770                                          target_module,
 771                                          import_directive,
 772                                          name,
 773                                          name_binding.clone());
 774         }
 775
 776         // Record the destination of this import
 777         if let Some(did) = target_module.def_id() {
 778             self.resolver.def_map.borrow_mut().insert(id,
 779                                                       PathResolution {
 780                                                           base_def: Def::Mod(did),
 781                                                           last_private: lp,
 782                                                           depth: 0,
 783                                                       });
 784         }
 785
 786         debug!("(resolving glob import) successfully resolved import");
 787         return ResolveResult::Success(());
 788     }
 789
 790     fn merge_import_resolution(&mut self,
 791                                module_: Module<'b>,
 792                                containing_module: Module<'b>,
 793                                import_directive: &ImportDirective,
 794                                (name, ns): (Name, Namespace),
 795                                name_binding: NameBinding<'b>) {
 796         let id = import_directive.id;
 797         let is_public = import_directive.is_public;
 798
 799         let mut import_resolutions = module_.import_resolutions.borrow_mut();
 800         let dest_import_resolution = import_resolutions.entry((name, ns)).or_insert_with(|| {
 801             ImportResolution::new(id, is_public)
 802         });
 803
 804         debug!("(resolving glob import) writing resolution `{}` in `{}` to `{}`",
 805                name,
 806                module_to_string(&*containing_module),
 807                module_to_string(module_));
 808
 809         // Merge the child item into the import resolution.
 810         let modifier = DefModifiers::IMPORTABLE | DefModifiers::PUBLIC;
 811
 812         if ns == TypeNS && is_public && name_binding.defined_with(DefModifiers::PRIVATE_VARIANT) {
 813             let msg = format!("variant `{}` is private, and cannot be reexported (error \
 814                                E0364), consider declaring its enum as `pub`", name);
 815             self.resolver.session.add_lint(lint::builtin::PRIVATE_IN_PUBLIC,
 816                                            import_directive.id,
 817                                            import_directive.span,
 818                                            msg);
 819         }
 820
 821         if name_binding.defined_with(modifier) {
 822             let namespace_name = match ns {
 823                 TypeNS => "type",
 824                 ValueNS => "value",
 825             };
 826             debug!("(resolving glob import) ... for {} target", namespace_name);
 827             if dest_import_resolution.shadowable() == Shadowable::Never {
 828                 let msg = format!("a {} named `{}` has already been imported in this module",
 829                                  namespace_name,
 830                                  name);
 831                 span_err!(self.resolver.session, import_directive.span, E0251, "{}", msg);
 832            } else {
 833                 let target = Target::new(containing_module,
 834                                          name_binding.clone(),
 835                                          import_directive.shadowable);
 836                 dest_import_resolution.target = Some(target);
 837                 dest_import_resolution.id = id;
 838                 dest_import_resolution.is_public = is_public;
 839                 self.add_export(module_, name, &dest_import_resolution);
 840             }
 841         } else {
 842             // FIXME #30159: This is required for backwards compatability.
 843             dest_import_resolution.is_public |= is_public;
 844         }
 845
 846         self.check_for_conflicts_between_imports_and_items(module_,
 847                                                            dest_import_resolution,
 848                                                            import_directive.span,
 849                                                            (name, ns));
 850     }
 851
 852     fn add_export(&mut self, module: Module<'b>, name: Name, resolution: &ImportResolution<'b>) {
 853         if !resolution.is_public { return }
 854         let node_id = match module.def_id() {
 855             Some(def_id) => self.resolver.ast_map.as_local_node_id(def_id).unwrap(),
 856             None => return,
 857         };
 858         let export = match resolution.target.as_ref().unwrap().binding.def() {
 859             Some(def) => Export { name: name, def_id: def.def_id() },
 860             None => return,
 861         };
 862         self.resolver.export_map.entry(node_id).or_insert(Vec::new()).push(export);
 863     }
 864
 865     /// Checks that imported names and items don't have the same name.
 866     fn check_for_conflicting_import(&mut self,
 867                                     import_resolution: &ImportResolution,
 868                                     import_span: Span,
 869                                     name: Name,
 870                                     namespace: Namespace) {
 871         let target = &import_resolution.target;
 872         debug!("check_for_conflicting_import: {}; target exists: {}",
 873                name,
 874                target.is_some());
 875
 876         match *target {
 877             Some(ref target) if target.shadowable != Shadowable::Always => {
 878                 let ns_word = match namespace {
 879                     TypeNS => {
 880                         match target.binding.module() {
 881                             Some(ref module) if module.is_normal() => "module",
 882                             Some(ref module) if module.is_trait() => "trait",
 883                             _ => "type",
 884                         }
 885                     }
 886                     ValueNS => "value",
 887                 };
 888                 let use_id = import_resolution.id;
 889                 let item = self.resolver.ast_map.expect_item(use_id);
 890                 let mut err = struct_span_err!(self.resolver.session,
 891                                                import_span,
 892                                                E0252,
 893                                                "a {} named `{}` has already been imported \
 894                                                 in this module",
 895                                                ns_word,
 896                                                name);
 897                 span_note!(&mut err,
 898                            item.span,
 899                            "previous import of `{}` here",
 900                            name);
 901                 err.emit();
 902             }
 903             Some(_) | None => {}
 904         }
 905     }
 906
 907     /// Checks that an import is actually importable
 908     fn check_that_import_is_importable(&mut self,
 909                                        name_binding: &NameBinding,
 910                                        import_span: Span,
 911                                        name: Name) {
 912         if !name_binding.defined_with(DefModifiers::IMPORTABLE) {
 913             let msg = format!("`{}` is not directly importable", name);
 914             span_err!(self.resolver.session, import_span, E0253, "{}", &msg[..]);
 915         }
 916     }
 917
 918     /// Checks that imported names and items don't have the same name.
 919     fn check_for_conflicts_between_imports_and_items(&mut self,
 920                                                      module: Module<'b>,
 921                                                      import: &ImportResolution<'b>,
 922                                                      import_span: Span,
 923                                                      (name, ns): (Name, Namespace)) {
 924         // First, check for conflicts between imports and `extern crate`s.
 925         if let TypeNS = ns {
 926             if module.external_module_children.borrow().contains_key(&name) {
 927                 match import.target {
 928                     Some(ref target) if target.shadowable != Shadowable::Always => {
 929                         let msg = format!("import `{0}` conflicts with imported crate \
 930                                            in this module (maybe you meant `use {0}::*`?)",
 931                                           name);
 932                         span_err!(self.resolver.session, import_span, E0254, "{}", &msg[..]);
 933                     }
 934                     Some(_) | None => {}
 935                 }
 936             }
 937         }
 938
 939         // Check for item conflicts.
 940         let name_binding = match module.get_child(name, ns) {
 941             None => {
 942                 // There can't be any conflicts.
 943                 return;
 944             }
 945             Some(name_binding) => name_binding,
 946         };
 947
 948         if let ValueNS = ns {
 949             match import.target {
 950                 Some(ref target) if target.shadowable != Shadowable::Always => {
 951                     let mut err = struct_span_err!(self.resolver.session,
 952                                                    import_span,
 953                                                    E0255,
 954                                                    "import `{}` conflicts with \
 955                                                     value in this module",
 956                                                    name);
 957                     if let Some(span) = name_binding.span {
 958                         err.span_note(span, "conflicting value here");
 959                     }
 960                     err.emit();
 961                 }
 962                 Some(_) | None => {}
 963             }
 964         } else {
 965             match import.target {
 966                 Some(ref target) if target.shadowable != Shadowable::Always => {
 967                     let (what, note) = match name_binding.module() {
 968                         Some(ref module) if module.is_normal() =>
 969                             ("existing submodule", "note conflicting module here"),
 970                         Some(ref module) if module.is_trait() =>
 971                             ("trait in this module", "note conflicting trait here"),
 972                         _ => ("type in this module", "note conflicting type here"),
 973                     };
 974                     let mut err = struct_span_err!(self.resolver.session,
 975                                                    import_span,
 976                                                    E0256,
 977                                                    "import `{}` conflicts with {}",
 978                                                    name,
 979                                                    what);
 980                     if let Some(span) = name_binding.span {
 981                         err.span_note(span, note);
 982                     }
 983                     err.emit();
 984                 }
 985                 Some(_) | None => {}
 986             }
 987         }
 988     }
 989 }
 990
 991 fn import_path_to_string(names: &[Name], subclass: ImportDirectiveSubclass) -> String {
 992     if names.is_empty() {
 993         import_directive_subclass_to_string(subclass)
 994     } else {
 995         (format!("{}::{}",
 996                  names_to_string(names),
 997                  import_directive_subclass_to_string(subclass)))
 998             .to_string()
 999     }
1000 }
1001
1002 fn import_directive_subclass_to_string(subclass: ImportDirectiveSubclass) -> String {
1003     match subclass {
1004         SingleImport(_, source) => source.to_string(),
1005         GlobImport => "*".to_string(),
1006     }
1007 }
1008
1009 pub fn resolve_imports(resolver: &mut Resolver) {
1010     let mut import_resolver = ImportResolver { resolver: resolver };
1011     import_resolver.resolve_imports();
1012 }