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::Determinacy::*;
  12 use self::ImportDirectiveSubclass::*;
  13
  14 use Module;
  15 use Namespace::{self, TypeNS, ValueNS};
  16 use {NameBinding, NameBindingKind, PrivacyError, ToNameBinding};
  17 use ResolveResult;
  18 use ResolveResult::*;
  19 use Resolver;
  20 use UseLexicalScopeFlag::DontUseLexicalScope;
  21 use {names_to_string, module_to_string};
  22 use {resolve_error, ResolutionError};
  23
  24 use rustc::ty;
  25 use rustc::lint::builtin::PRIVATE_IN_PUBLIC;
  26 use rustc::hir::def::*;
  27
  28 use syntax::ast::{NodeId, Name};
  29 use syntax::util::lev_distance::find_best_match_for_name;
  30 use syntax_pos::{Span, DUMMY_SP};
  31
  32 use std::cell::{Cell, RefCell};
  33
  34 impl<'a> Resolver<'a> {
  35     pub fn resolve_imports(&mut self) {
  36         ImportResolver { resolver: self }.resolve_imports();
  37     }
  38 }
  39
  40 #[derive(Copy, Clone, Debug)]
  41 pub enum Determinacy {
  42     Determined,
  43     Undetermined,
  44 }
  45
  46 /// Contains data for specific types of import directives.
  47 #[derive(Clone, Debug)]
  48 pub enum ImportDirectiveSubclass<'a> {
  49     SingleImport {
  50         target: Name,
  51         source: Name,
  52         value_result: Cell<Result<&'a NameBinding<'a>, Determinacy>>,
  53         type_result: Cell<Result<&'a NameBinding<'a>, Determinacy>>,
  54     },
  55     GlobImport { is_prelude: bool },
  56 }
  57
  58 impl<'a> ImportDirectiveSubclass<'a> {
  59     pub fn single(target: Name, source: Name) -> Self {
  60         SingleImport {
  61             target: target,
  62             source: source,
  63             type_result: Cell::new(Err(Undetermined)),
  64             value_result: Cell::new(Err(Undetermined)),
  65         }
  66     }
  67 }
  68
  69 /// One import directive.
  70 #[derive(Debug,Clone)]
  71 pub struct ImportDirective<'a> {
  72     pub id: NodeId,
  73     parent: Module<'a>,
  74     module_path: Vec<Name>,
  75     imported_module: Cell<Option<Module<'a>>>, // the resolution of `module_path`
  76     subclass: ImportDirectiveSubclass<'a>,
  77     span: Span,
  78     vis: Cell<ty::Visibility>,
  79 }
  80
  81 impl<'a> ImportDirective<'a> {
  82     pub fn is_glob(&self) -> bool {
  83         match self.subclass { ImportDirectiveSubclass::GlobImport { .. } => true, _ => false }
  84     }
  85 }
  86
  87 #[derive(Clone, Default)]
  88 /// Records information about the resolution of a name in a namespace of a module.
  89 pub struct NameResolution<'a> {
  90     /// The single imports that define the name in the namespace.
  91     single_imports: SingleImports<'a>,
  92     /// The least shadowable known binding for this name, or None if there are no known bindings.
  93     pub binding: Option<&'a NameBinding<'a>>,
  94     duplicate_globs: Vec<&'a NameBinding<'a>>,
  95 }
  96
  97 #[derive(Clone, Debug)]
  98 enum SingleImports<'a> {
  99     /// No single imports can define the name in the namespace.
 100     None,
 101     /// Only the given single import can define the name in the namespace.
 102     MaybeOne(&'a ImportDirective<'a>),
 103     /// At least one single import will define the name in the namespace.
 104     AtLeastOne,
 105 }
 106
 107 impl<'a> Default for SingleImports<'a> {
 108     fn default() -> Self {
 109         SingleImports::None
 110     }
 111 }
 112
 113 impl<'a> SingleImports<'a> {
 114     fn add_directive(&mut self, directive: &'a ImportDirective<'a>) {
 115         match *self {
 116             SingleImports::None => *self = SingleImports::MaybeOne(directive),
 117             // If two single imports can define the name in the namespace, we can assume that at
 118             // least one of them will define it since otherwise both would have to define only one
 119             // namespace, leading to a duplicate error.
 120             SingleImports::MaybeOne(_) => *self = SingleImports::AtLeastOne,
 121             SingleImports::AtLeastOne => {}
 122         };
 123     }
 124
 125     fn directive_failed(&mut self) {
 126         match *self {
 127             SingleImports::None => unreachable!(),
 128             SingleImports::MaybeOne(_) => *self = SingleImports::None,
 129             SingleImports::AtLeastOne => {}
 130         }
 131     }
 132 }
 133
 134 impl<'a> NameResolution<'a> {
 135     // Returns the binding for the name if it is known or None if it not known.
 136     fn binding(&self) -> Option<&'a NameBinding<'a>> {
 137         self.binding.and_then(|binding| match self.single_imports {
 138             SingleImports::None => Some(binding),
 139             _ if !binding.is_glob_import() => Some(binding),
 140             _ => None, // The binding could be shadowed by a single import, so it is not known.
 141         })
 142     }
 143 }
 144
 145 impl<'a> Resolver<'a> {
 146     fn resolution(&self, module: Module<'a>, name: Name, ns: Namespace)
 147                   -> &'a RefCell<NameResolution<'a>> {
 148         *module.resolutions.borrow_mut().entry((name, ns))
 149                .or_insert_with(|| self.arenas.alloc_name_resolution())
 150     }
 151
 152     /// Attempts to resolve the supplied name in the given module for the given namespace.
 153     /// If successful, returns the binding corresponding to the name.
 154     /// Invariant: if `record_used` is `Some`, import resolution must be complete.
 155     pub fn resolve_name_in_module(&mut self,
 156                                   module: Module<'a>,
 157                                   name: Name,
 158                                   ns: Namespace,
 159                                   allow_private_imports: bool,
 160                                   record_used: Option<Span>)
 161                                   -> ResolveResult<&'a NameBinding<'a>> {
 162         self.populate_module_if_necessary(module);
 163
 164         let resolution = self.resolution(module, name, ns);
 165         let resolution = match resolution.borrow_state() {
 166             ::std::cell::BorrowState::Unused => resolution.borrow_mut(),
 167             _ => return Failed(None), // This happens when there is a cycle of imports
 168         };
 169
 170         let is_disallowed_private_import = |binding: &NameBinding| {
 171             !allow_private_imports && !binding.is_pseudo_public() && binding.is_import()
 172         };
 173
 174         if let Some(span) = record_used {
 175             if let Some(binding) = resolution.binding {
 176                 if is_disallowed_private_import(binding) {
 177                     return Failed(None);
 178                 }
 179                 self.record_use(name, ns, binding);
 180                 if !self.is_accessible(binding.vis) {
 181                     self.privacy_errors.push(PrivacyError(span, name, binding));
 182                 }
 183             }
 184
 185             return resolution.binding.map(Success).unwrap_or(Failed(None));
 186         }
 187
 188         // If the resolution doesn't depend on glob definability, check privacy and return.
 189         if let Some(result) = self.try_result(&resolution, ns) {
 190             return result.and_then(|binding| {
 191                 if self.is_accessible(binding.vis) && !is_disallowed_private_import(binding) {
 192                     Success(binding)
 193                 } else {
 194                     Failed(None)
 195                 }
 196             });
 197         }
 198
 199         // Check if the globs are determined
 200         for directive in module.globs.borrow().iter() {
 201             if self.is_accessible(directive.vis.get()) {
 202                 if let Some(module) = directive.imported_module.get() {
 203                     let result = self.resolve_name_in_module(module, name, ns, true, None);
 204                     if let Indeterminate = result {
 205                         return Indeterminate;
 206                     }
 207                 } else {
 208                     return Indeterminate;
 209                 }
 210             }
 211         }
 212
 213         Failed(None)
 214     }
 215
 216     // Returns Some(the resolution of the name), or None if the resolution depends
 217     // on whether more globs can define the name.
 218     fn try_result(&mut self, resolution: &NameResolution<'a>, ns: Namespace)
 219                   -> Option<ResolveResult<&'a NameBinding<'a>>> {
 220         match resolution.binding {
 221             Some(binding) if !binding.is_glob_import() =>
 222                 return Some(Success(binding)), // Items and single imports are not shadowable.
 223             _ => {}
 224         };
 225
 226         // Check if a single import can still define the name.
 227         match resolution.single_imports {
 228             SingleImports::AtLeastOne => return Some(Indeterminate),
 229             SingleImports::MaybeOne(directive) if self.is_accessible(directive.vis.get()) => {
 230                 let module = match directive.imported_module.get() {
 231                     Some(module) => module,
 232                     None => return Some(Indeterminate),
 233                 };
 234                 let name = match directive.subclass {
 235                     SingleImport { source, .. } => source,
 236                     GlobImport { .. } => unreachable!(),
 237                 };
 238                 match self.resolve_name_in_module(module, name, ns, true, None) {
 239                     Failed(_) => {}
 240                     _ => return Some(Indeterminate),
 241                 }
 242             }
 243             SingleImports::MaybeOne(_) | SingleImports::None => {},
 244         }
 245
 246         resolution.binding.map(Success)
 247     }
 248
 249     // Add an import directive to the current module.
 250     pub fn add_import_directive(&mut self,
 251                                 module_path: Vec<Name>,
 252                                 subclass: ImportDirectiveSubclass<'a>,
 253                                 span: Span,
 254                                 id: NodeId,
 255                                 vis: ty::Visibility) {
 256         let current_module = self.current_module;
 257         let directive = self.arenas.alloc_import_directive(ImportDirective {
 258             parent: current_module,
 259             module_path: module_path,
 260             imported_module: Cell::new(None),
 261             subclass: subclass,
 262             span: span,
 263             id: id,
 264             vis: Cell::new(vis),
 265         });
 266
 267         self.indeterminate_imports.push(directive);
 268         match directive.subclass {
 269             SingleImport { target, .. } => {
 270                 for &ns in &[ValueNS, TypeNS] {
 271                     let mut resolution = self.resolution(current_module, target, ns).borrow_mut();
 272                     resolution.single_imports.add_directive(directive);
 273                 }
 274             }
 275             // We don't add prelude imports to the globs since they only affect lexical scopes,
 276             // which are not relevant to import resolution.
 277             GlobImport { is_prelude: true } => {}
 278             GlobImport { .. } => self.current_module.globs.borrow_mut().push(directive),
 279         }
 280     }
 281
 282     // Given a binding and an import directive that resolves to it,
 283     // return the corresponding binding defined by the import directive.
 284     fn import(&mut self, binding: &'a NameBinding<'a>, directive: &'a ImportDirective<'a>)
 285               -> NameBinding<'a> {
 286         NameBinding {
 287             kind: NameBindingKind::Import {
 288                 binding: binding,
 289                 directive: directive,
 290             },
 291             span: directive.span,
 292             vis: directive.vis.get(),
 293         }
 294     }
 295
 296     // Define the name or return the existing binding if there is a collision.
 297     pub fn try_define<T>(&mut self, module: Module<'a>, name: Name, ns: Namespace, binding: T)
 298                          -> Result<(), &'a NameBinding<'a>>
 299         where T: ToNameBinding<'a>
 300     {
 301         let binding = self.arenas.alloc_name_binding(binding.to_name_binding());
 302         self.update_resolution(module, name, ns, |_, resolution| {
 303             if let Some(old_binding) = resolution.binding {
 304                 if binding.is_glob_import() {
 305                     resolution.duplicate_globs.push(binding);
 306                 } else if old_binding.is_glob_import() {
 307                     resolution.duplicate_globs.push(old_binding);
 308                     resolution.binding = Some(binding);
 309                 } else {
 310                     return Err(old_binding);
 311                 }
 312             } else {
 313                 resolution.binding = Some(binding);
 314             }
 315
 316             Ok(())
 317         })
 318     }
 319
 320     // Use `f` to mutate the resolution of the name in the module.
 321     // If the resolution becomes a success, define it in the module's glob importers.
 322     fn update_resolution<T, F>(&mut self, module: Module<'a>, name: Name, ns: Namespace, f: F) -> T
 323         where F: FnOnce(&mut Resolver<'a>, &mut NameResolution<'a>) -> T
 324     {
 325         // Ensure that `resolution` isn't borrowed when defining in the module's glob importers,
 326         // during which the resolution might end up getting re-defined via a glob cycle.
 327         let (new_binding, t) = {
 328             let mut resolution = &mut *self.resolution(module, name, ns).borrow_mut();
 329             let was_known = resolution.binding().is_some();
 330
 331             let t = f(self, resolution);
 332
 333             if was_known { return t; }
 334             match resolution.binding() {
 335                 Some(binding) => (binding, t),
 336                 None => return t,
 337             }
 338         };
 339
 340         // Define `new_binding` in `module`s glob importers.
 341         if new_binding.is_importable() && new_binding.is_pseudo_public() {
 342             for directive in module.glob_importers.borrow_mut().iter() {
 343                 let imported_binding = self.import(new_binding, directive);
 344                 let _ = self.try_define(directive.parent, name, ns, imported_binding);
 345             }
 346         }
 347
 348         t
 349     }
 350 }
 351
 352 struct ImportResolver<'a, 'b: 'a> {
 353     resolver: &'a mut Resolver<'b>,
 354 }
 355
 356 impl<'a, 'b: 'a> ::std::ops::Deref for ImportResolver<'a, 'b> {
 357     type Target = Resolver<'b>;
 358     fn deref(&self) -> &Resolver<'b> {
 359         self.resolver
 360     }
 361 }
 362
 363 impl<'a, 'b: 'a> ::std::ops::DerefMut for ImportResolver<'a, 'b> {
 364     fn deref_mut(&mut self) -> &mut Resolver<'b> {
 365         self.resolver
 366     }
 367 }
 368
 369 impl<'a, 'b: 'a> ty::NodeIdTree for ImportResolver<'a, 'b> {
 370     fn is_descendant_of(&self, node: NodeId, ancestor: NodeId) -> bool {
 371         self.resolver.is_descendant_of(node, ancestor)
 372     }
 373 }
 374
 375 impl<'a, 'b:'a> ImportResolver<'a, 'b> {
 376     // Import resolution
 377     //
 378     // This is a fixed-point algorithm. We resolve imports until our efforts
 379     // are stymied by an unresolved import; then we bail out of the current
 380     // module and continue. We terminate successfully once no more imports
 381     // remain or unsuccessfully when no forward progress in resolving imports
 382     // is made.
 383
 384     fn set_current_module(&mut self, module: Module<'b>) {
 385         self.current_module = module;
 386         self.current_vis = ty::Visibility::Restricted({
 387             let normal_module = self.get_nearest_normal_module_parent_or_self(module);
 388             self.definitions.as_local_node_id(normal_module.def_id().unwrap()).unwrap()
 389         });
 390     }
 391
 392     /// Resolves all imports for the crate. This method performs the fixed-
 393     /// point iteration.
 394     fn resolve_imports(&mut self) {
 395         let mut i = 0;
 396         let mut prev_num_indeterminates = self.indeterminate_imports.len() + 1;
 397
 398         while self.indeterminate_imports.len() < prev_num_indeterminates {
 399             prev_num_indeterminates = self.indeterminate_imports.len();
 400             debug!("(resolving imports) iteration {}, {} imports left", i, prev_num_indeterminates);
 401
 402             let mut imports = Vec::new();
 403             ::std::mem::swap(&mut imports, &mut self.indeterminate_imports);
 404
 405             for import in imports {
 406                 match self.resolve_import(&import) {
 407                     Failed(_) => self.determined_imports.push(import),
 408                     Indeterminate => self.indeterminate_imports.push(import),
 409                     Success(()) => self.determined_imports.push(import),
 410                 }
 411             }
 412
 413             i += 1;
 414         }
 415
 416         for module in self.arenas.local_modules().iter() {
 417             self.finalize_resolutions_in(module);
 418         }
 419
 420         let mut errors = false;
 421         for i in 0 .. self.determined_imports.len() {
 422             let import = self.determined_imports[i];
 423             if let Failed(err) = self.finalize_import(import) {
 424                 errors = true;
 425                 let (span, help) = match err {
 426                     Some((span, msg)) => (span, msg),
 427                     None => (import.span, String::new()),
 428                 };
 429
 430                 // If the error is a single failed import then create a "fake" import
 431                 // resolution for it so that later resolve stages won't complain.
 432                 self.import_dummy_binding(import);
 433                 let path = import_path_to_string(&import.module_path, &import.subclass);
 434                 let error = ResolutionError::UnresolvedImport(Some((&path, &help)));
 435                 resolve_error(self.resolver, span, error);
 436             }
 437         }
 438
 439         // Report unresolved imports only if no hard error was already reported
 440         // to avoid generating multiple errors on the same import.
 441         if !errors {
 442             if let Some(import) = self.indeterminate_imports.iter().next() {
 443                 let error = ResolutionError::UnresolvedImport(None);
 444                 resolve_error(self.resolver, import.span, error);
 445             }
 446         }
 447     }
 448
 449     // Define a "dummy" resolution containing a Def::Err as a placeholder for a
 450     // failed resolution
 451     fn import_dummy_binding(&mut self, directive: &'b ImportDirective<'b>) {
 452         if let SingleImport { target, .. } = directive.subclass {
 453             let dummy_binding = self.arenas.alloc_name_binding(NameBinding {
 454                 kind: NameBindingKind::Def(Def::Err),
 455                 span: DUMMY_SP,
 456                 vis: ty::Visibility::Public,
 457             });
 458             let dummy_binding = self.import(dummy_binding, directive);
 459
 460             let _ = self.try_define(directive.parent, target, ValueNS, dummy_binding.clone());
 461             let _ = self.try_define(directive.parent, target, TypeNS, dummy_binding);
 462         }
 463     }
 464
 465     /// Attempts to resolve the given import. The return value indicates
 466     /// failure if we're certain the name does not exist, indeterminate if we
 467     /// don't know whether the name exists at the moment due to other
 468     /// currently-unresolved imports, or success if we know the name exists.
 469     /// If successful, the resolved bindings are written into the module.
 470     fn resolve_import(&mut self, directive: &'b ImportDirective<'b>) -> ResolveResult<()> {
 471         debug!("(resolving import for module) resolving import `{}::...` in `{}`",
 472                names_to_string(&directive.module_path),
 473                module_to_string(self.current_module));
 474
 475         self.set_current_module(directive.parent);
 476
 477         let module = if let Some(module) = directive.imported_module.get() {
 478             module
 479         } else {
 480             let vis = directive.vis.get();
 481             // For better failure detection, pretend that the import will not define any names
 482             // while resolving its module path.
 483             directive.vis.set(ty::Visibility::PrivateExternal);
 484             let result =
 485                 self.resolve_module_path(&directive.module_path, DontUseLexicalScope, None);
 486             directive.vis.set(vis);
 487
 488             match result {
 489                 Success(module) => module,
 490                 Indeterminate => return Indeterminate,
 491                 Failed(err) => return Failed(err),
 492             }
 493         };
 494
 495         directive.imported_module.set(Some(module));
 496         let (source, target, value_result, type_result) = match directive.subclass {
 497             SingleImport { source, target, ref value_result, ref type_result } =>
 498                 (source, target, value_result, type_result),
 499             GlobImport { .. } => {
 500                 self.resolve_glob_import(directive);
 501                 return Success(());
 502             }
 503         };
 504
 505         let mut indeterminate = false;
 506         for &(ns, result) in &[(ValueNS, value_result), (TypeNS, type_result)] {
 507             if let Err(Undetermined) = result.get() {
 508                 result.set({
 509                     match self.resolve_name_in_module(module, source, ns, false, None) {
 510                         Success(binding) => Ok(binding),
 511                         Indeterminate => Err(Undetermined),
 512                         Failed(_) => Err(Determined),
 513                     }
 514                 });
 515             } else {
 516                 continue
 517             };
 518
 519             match result.get() {
 520                 Err(Undetermined) => indeterminate = true,
 521                 Err(Determined) => {
 522                     self.update_resolution(directive.parent, target, ns, |_, resolution| {
 523                         resolution.single_imports.directive_failed()
 524                     });
 525                 }
 526                 Ok(binding) if !binding.is_importable() => {
 527                     let msg = format!("`{}` is not directly importable", target);
 528                     struct_span_err!(self.session, directive.span, E0253, "{}", &msg)
 529                         .span_label(directive.span, &format!("cannot be imported directly"))
 530                         .emit();
 531                     // Do not import this illegal binding. Import a dummy binding and pretend
 532                     // everything is fine
 533                     self.import_dummy_binding(directive);
 534                     return Success(());
 535                 }
 536                 Ok(binding) => {
 537                     let imported_binding = self.import(binding, directive);
 538                     let conflict = self.try_define(directive.parent, target, ns, imported_binding);
 539                     if let Err(old_binding) = conflict {
 540                         let binding = &self.import(binding, directive);
 541                         self.report_conflict(directive.parent, target, ns, binding, old_binding);
 542                     }
 543                 }
 544             }
 545         }
 546
 547         if indeterminate { Indeterminate } else { Success(()) }
 548     }
 549
 550     fn finalize_import(&mut self, directive: &'b ImportDirective<'b>) -> ResolveResult<()> {
 551         self.set_current_module(directive.parent);
 552
 553         let ImportDirective { ref module_path, span, .. } = *directive;
 554         let module_result = self.resolve_module_path(&module_path, DontUseLexicalScope, Some(span));
 555         let module = match module_result {
 556             Success(module) => module,
 557             Indeterminate => return Indeterminate,
 558             Failed(err) => return Failed(err),
 559         };
 560
 561         let (name, value_result, type_result) = match directive.subclass {
 562             SingleImport { source, ref value_result, ref type_result, .. } =>
 563                 (source, value_result.get(), type_result.get()),
 564             GlobImport { .. } if module.def_id() == directive.parent.def_id() => {
 565                 // Importing a module into itself is not allowed.
 566                 let msg = "Cannot glob-import a module into itself.".into();
 567                 return Failed(Some((directive.span, msg)));
 568             }
 569             GlobImport { .. } => return Success(()),
 570         };
 571
 572         for &(ns, result) in &[(ValueNS, value_result), (TypeNS, type_result)] {
 573             if let Ok(binding) = result {
 574                 self.record_use(name, ns, binding);
 575             }
 576         }
 577
 578         if value_result.is_err() && type_result.is_err() {
 579             let (value_result, type_result);
 580             value_result = self.resolve_name_in_module(module, name, ValueNS, false, Some(span));
 581             type_result = self.resolve_name_in_module(module, name, TypeNS, false, Some(span));
 582
 583             return if let (Failed(_), Failed(_)) = (value_result, type_result) {
 584                 let resolutions = module.resolutions.borrow();
 585                 let names = resolutions.iter().filter_map(|(&(ref n, _), resolution)| {
 586                     if *n == name { return None; } // Never suggest the same name
 587                     match *resolution.borrow() {
 588                         NameResolution { binding: Some(_), .. } => Some(n),
 589                         NameResolution { single_imports: SingleImports::None, .. } => None,
 590                         _ => Some(n),
 591                     }
 592                 });
 593                 let lev_suggestion = match find_best_match_for_name(names, &name.as_str(), None) {
 594                     Some(name) => format!(". Did you mean to use `{}`?", name),
 595                     None => "".to_owned(),
 596                 };
 597                 let module_str = module_to_string(module);
 598                 let msg = if &module_str == "???" {
 599                     format!("no `{}` in the root{}", name, lev_suggestion)
 600                 } else {
 601                     format!("no `{}` in `{}`{}", name, module_str, lev_suggestion)
 602                 };
 603                 Failed(Some((directive.span, msg)))
 604             } else {
 605                 // `resolve_name_in_module` reported a privacy error.
 606                 self.import_dummy_binding(directive);
 607                 Success(())
 608             }
 609         }
 610
 611         match (value_result, type_result) {
 612             (Ok(binding), _) if !binding.pseudo_vis().is_at_least(directive.vis.get(), self) => {
 613                 let msg = format!("`{}` is private, and cannot be reexported", name);
 614                 let note_msg =
 615                     format!("consider marking `{}` as `pub` in the imported module", name);
 616                 struct_span_err!(self.session, directive.span, E0364, "{}", &msg)
 617                     .span_note(directive.span, &note_msg)
 618                     .emit();
 619             }
 620
 621             (_, Ok(binding)) if !binding.pseudo_vis().is_at_least(directive.vis.get(), self) => {
 622                 if binding.is_extern_crate() {
 623                     let msg = format!("extern crate `{}` is private, and cannot be reexported \
 624                                        (error E0364), consider declaring with `pub`",
 625                                        name);
 626                     self.session.add_lint(PRIVATE_IN_PUBLIC, directive.id, directive.span, msg);
 627                 } else {
 628                     struct_span_err!(self.session, directive.span, E0365,
 629                                      "`{}` is private, and cannot be reexported", name)
 630                         .span_label(directive.span, &format!("reexport of private `{}`", name))
 631                         .note(&format!("consider declaring type or module `{}` with `pub`", name))
 632                         .emit();
 633                 }
 634             }
 635
 636             _ => {}
 637         }
 638
 639         // Record what this import resolves to for later uses in documentation,
 640         // this may resolve to either a value or a type, but for documentation
 641         // purposes it's good enough to just favor one over the other.
 642         let def = match type_result.ok().and_then(NameBinding::def) {
 643             Some(def) => def,
 644             None => value_result.ok().and_then(NameBinding::def).unwrap(),
 645         };
 646         let path_resolution = PathResolution::new(def);
 647         self.def_map.insert(directive.id, path_resolution);
 648
 649         debug!("(resolving single import) successfully resolved import");
 650         return Success(());
 651     }
 652
 653     fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) {
 654         let module = directive.imported_module.get().unwrap();
 655         self.populate_module_if_necessary(module);
 656
 657         if let Some(Def::Trait(_)) = module.def {
 658             self.session.span_err(directive.span, "items in traits are not importable.");
 659         }
 660
 661         if module.def_id() == directive.parent.def_id()  {
 662             return;
 663         } else if let GlobImport { is_prelude: true } = directive.subclass {
 664             self.prelude = Some(module);
 665             return;
 666         }
 667
 668         // Add to module's glob_importers
 669         module.glob_importers.borrow_mut().push(directive);
 670
 671         // Ensure that `resolutions` isn't borrowed during `try_define`,
 672         // since it might get updated via a glob cycle.
 673         let bindings = module.resolutions.borrow().iter().filter_map(|(name, resolution)| {
 674             resolution.borrow().binding().map(|binding| (*name, binding))
 675         }).collect::<Vec<_>>();
 676         for ((name, ns), binding) in bindings {
 677             if binding.is_importable() && binding.is_pseudo_public() {
 678                 let imported_binding = self.import(binding, directive);
 679                 let _ = self.try_define(directive.parent, name, ns, imported_binding);
 680             }
 681         }
 682
 683         // Record the destination of this import
 684         if let Some(did) = module.def_id() {
 685             let resolution = PathResolution::new(Def::Mod(did));
 686             self.def_map.insert(directive.id, resolution);
 687         }
 688     }
 689
 690     // Miscellaneous post-processing, including recording reexports, reporting conflicts,
 691     // reporting the PRIVATE_IN_PUBLIC lint, and reporting unresolved imports.
 692     fn finalize_resolutions_in(&mut self, module: Module<'b>) {
 693         // Since import resolution is finished, globs will not define any more names.
 694         *module.globs.borrow_mut() = Vec::new();
 695
 696         let mut reexports = Vec::new();
 697         for (&(name, ns), resolution) in module.resolutions.borrow().iter() {
 698             let resolution = resolution.borrow();
 699             let binding = match resolution.binding {
 700                 Some(binding) => binding,
 701                 None => continue,
 702             };
 703
 704             // Report conflicts
 705             for duplicate_glob in resolution.duplicate_globs.iter() {
 706                 // FIXME #31337: We currently allow items to shadow glob-imported re-exports.
 707                 if !binding.is_import() {
 708                     if let NameBindingKind::Import { binding, .. } = duplicate_glob.kind {
 709                         if binding.is_import() { continue }
 710                     }
 711                 }
 712
 713                 self.report_conflict(module, name, ns, duplicate_glob, binding);
 714             }
 715
 716             if binding.vis == ty::Visibility::Public &&
 717                (binding.is_import() || binding.is_extern_crate()) {
 718                 if let Some(def) = binding.def() {
 719                     reexports.push(Export { name: name, def_id: def.def_id() });
 720                 }
 721             }
 722
 723             if let NameBindingKind::Import { binding: orig_binding, directive, .. } = binding.kind {
 724                 if ns == TypeNS && orig_binding.is_variant() &&
 725                    !orig_binding.vis.is_at_least(binding.vis, self) {
 726                     let msg = format!("variant `{}` is private, and cannot be reexported \
 727                                        (error E0364), consider declaring its enum as `pub`",
 728                                       name);
 729                     self.session.add_lint(PRIVATE_IN_PUBLIC, directive.id, binding.span, msg);
 730                 }
 731             }
 732         }
 733
 734         if reexports.len() > 0 {
 735             if let Some(def_id) = module.def_id() {
 736                 let node_id = self.definitions.as_local_node_id(def_id).unwrap();
 737                 self.export_map.insert(node_id, reexports);
 738             }
 739         }
 740     }
 741 }
 742
 743 fn import_path_to_string(names: &[Name], subclass: &ImportDirectiveSubclass) -> String {
 744     if names.is_empty() {
 745         import_directive_subclass_to_string(subclass)
 746     } else {
 747         (format!("{}::{}",
 748                  names_to_string(names),
 749                  import_directive_subclass_to_string(subclass)))
 750             .to_string()
 751     }
 752 }
 753
 754 fn import_directive_subclass_to_string(subclass: &ImportDirectiveSubclass) -> String {
 755     match *subclass {
 756         SingleImport { source, .. } => source.to_string(),
 757         GlobImport { .. } => "*".to_string(),
 758     }
 759 }