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