src/librustc_resolve/build_reduced_graph.rs

   1 // Copyright 2012-2014 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 //! Reduced graph building
  12 //!
  13 //! Here we build the "reduced graph": the graph of the module tree without
  14 //! any imports resolved.
  15
  16 use DefModifiers;
  17 use resolve_imports::ImportDirective;
  18 use resolve_imports::ImportDirectiveSubclass::{self, SingleImport, GlobImport};
  19 use resolve_imports::ImportResolution;
  20 use Module;
  21 use ModuleKind::*;
  22 use Namespace::{TypeNS, ValueNS};
  23 use NameBindings;
  24 use {names_to_string, module_to_string};
  25 use ParentLink::{self, ModuleParentLink, BlockParentLink};
  26 use Resolver;
  27 use resolve_imports::Shadowable;
  28 use TypeNsDef;
  29 use {resolve_error, ResolutionError};
  30
  31 use self::DuplicateCheckingMode::*;
  32 use self::NamespaceError::*;
  33
  34 use rustc::metadata::csearch;
  35 use rustc::metadata::decoder::{DefLike, DlDef, DlField, DlImpl};
  36 use rustc::middle::def::*;
  37 use rustc::middle::def_id::DefId;
  38
  39 use syntax::ast::{Name, NodeId};
  40 use syntax::attr::AttrMetaMethods;
  41 use syntax::parse::token::special_idents;
  42 use syntax::codemap::{Span, DUMMY_SP};
  43
  44 use rustc_front::hir;
  45 use rustc_front::hir::{Block, Crate, DeclItem};
  46 use rustc_front::hir::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  47 use rustc_front::hir::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  48 use rustc_front::hir::{ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  49 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  50 use rustc_front::hir::{NamedField, PathListIdent, PathListMod, Public};
  51 use rustc_front::hir::StmtDecl;
  52 use rustc_front::hir::StructVariantKind;
  53 use rustc_front::hir::TupleVariantKind;
  54 use rustc_front::hir::UnnamedField;
  55 use rustc_front::hir::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  56 use rustc_front::hir::Visibility;
  57 use rustc_front::visit::{self, Visitor};
  58
  59 use std::mem::replace;
  60 use std::ops::{Deref, DerefMut};
  61 use std::rc::Rc;
  62
  63 // Specifies how duplicates should be handled when adding a child item if
  64 // another item exists with the same name in some namespace.
  65 #[derive(Copy, Clone, PartialEq)]
  66 enum DuplicateCheckingMode {
  67     ForbidDuplicateModules,
  68     ForbidDuplicateTypesAndModules,
  69     ForbidDuplicateValues,
  70     ForbidDuplicateTypesAndValues,
  71     OverwriteDuplicates
  72 }
  73
  74 #[derive(Copy, Clone, PartialEq)]
  75 enum NamespaceError {
  76     NoError,
  77     ModuleError,
  78     TypeError,
  79     ValueError
  80 }
  81
  82 fn namespace_error_to_string(ns: NamespaceError) -> &'static str {
  83     match ns {
  84         NoError                 => "",
  85         ModuleError | TypeError => "type or module",
  86         ValueError              => "value",
  87     }
  88 }
  89
  90 struct GraphBuilder<'a, 'b:'a, 'tcx:'b> {
  91     resolver: &'a mut Resolver<'b, 'tcx>
  92 }
  93
  94 impl<'a, 'b:'a, 'tcx:'b> Deref for GraphBuilder<'a, 'b, 'tcx> {
  95     type Target = Resolver<'b, 'tcx>;
  96
  97     fn deref(&self) -> &Resolver<'b, 'tcx> {
  98         &*self.resolver
  99     }
 100 }
 101
 102 impl<'a, 'b:'a, 'tcx:'b> DerefMut for GraphBuilder<'a, 'b, 'tcx> {
 103     fn deref_mut(&mut self) -> &mut Resolver<'b, 'tcx> {
 104         &mut *self.resolver
 105     }
 106 }
 107
 108 impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 109     /// Constructs the reduced graph for the entire crate.
 110     fn build_reduced_graph(self, krate: &hir::Crate) {
 111         let parent = self.graph_root.get_module();
 112         let mut visitor = BuildReducedGraphVisitor {
 113             builder: self,
 114             parent: parent
 115         };
 116         visit::walk_crate(&mut visitor, krate);
 117     }
 118
 119     /// Adds a new child item to the module definition of the parent node and
 120     /// returns its corresponding name bindings as well as the current parent.
 121     /// Or, if we're inside a block, creates (or reuses) an anonymous module
 122     /// corresponding to the innermost block ID and returns the name bindings
 123     /// as well as the newly-created parent.
 124     ///
 125     /// # Panics
 126     ///
 127     /// Panics if this node does not have a module definition and we are not inside
 128     /// a block.
 129     fn add_child(&self,
 130                  name: Name,
 131                  parent: &Rc<Module>,
 132                  duplicate_checking_mode: DuplicateCheckingMode,
 133                  // For printing errors
 134                  sp: Span)
 135                  -> Rc<NameBindings> {
 136         // If this is the immediate descendant of a module, then we add the
 137         // child name directly. Otherwise, we create or reuse an anonymous
 138         // module and add the child to that.
 139
 140         self.check_for_conflicts_between_external_crates_and_items(&**parent,
 141                                                                    name,
 142                                                                    sp);
 143
 144         // Add or reuse the child.
 145         let child = parent.children.borrow().get(&name).cloned();
 146         match child {
 147             None => {
 148                 let child = Rc::new(NameBindings::new());
 149                 parent.children.borrow_mut().insert(name, child.clone());
 150                 child
 151             }
 152             Some(child) => {
 153                 // Enforce the duplicate checking mode:
 154                 //
 155                 // * If we're requesting duplicate module checking, check that
 156                 //   there isn't a module in the module with the same name.
 157                 //
 158                 // * If we're requesting duplicate type checking, check that
 159                 //   there isn't a type in the module with the same name.
 160                 //
 161                 // * If we're requesting duplicate value checking, check that
 162                 //   there isn't a value in the module with the same name.
 163                 //
 164                 // * If we're requesting duplicate type checking and duplicate
 165                 //   value checking, check that there isn't a duplicate type
 166                 //   and a duplicate value with the same name.
 167                 //
 168                 // * If no duplicate checking was requested at all, do
 169                 //   nothing.
 170
 171                 let mut duplicate_type = NoError;
 172                 let ns = match duplicate_checking_mode {
 173                     ForbidDuplicateModules => {
 174                         if child.get_module_if_available().is_some() {
 175                             duplicate_type = ModuleError;
 176                         }
 177                         Some(TypeNS)
 178                     }
 179                     ForbidDuplicateTypesAndModules => {
 180                         if child.defined_in_namespace(TypeNS) {
 181                             duplicate_type = TypeError;
 182                         }
 183                         Some(TypeNS)
 184                     }
 185                     ForbidDuplicateValues => {
 186                         if child.defined_in_namespace(ValueNS) {
 187                             duplicate_type = ValueError;
 188                         }
 189                         Some(ValueNS)
 190                     }
 191                     ForbidDuplicateTypesAndValues => {
 192                         let mut n = None;
 193                         match child.def_for_namespace(TypeNS) {
 194                             Some(DefMod(_)) | None => {}
 195                             Some(_) => {
 196                                 n = Some(TypeNS);
 197                                 duplicate_type = TypeError;
 198                             }
 199                         };
 200                         if child.defined_in_namespace(ValueNS) {
 201                             duplicate_type = ValueError;
 202                             n = Some(ValueNS);
 203                         }
 204                         n
 205                     }
 206                     OverwriteDuplicates => None
 207                 };
 208                 if duplicate_type != NoError {
 209                     // Return an error here by looking up the namespace that
 210                     // had the duplicate.
 211                     let ns = ns.unwrap();
 212                     resolve_error(
 213                         self,
 214                         sp,
 215                         ResolutionError::DuplicateDefinition(
 216                             namespace_error_to_string(duplicate_type),
 217                             name)
 218                     );
 219                     {
 220                         let r = child.span_for_namespace(ns);
 221                         if let Some(sp) = r {
 222                             self.session.span_note(sp,
 223                                  &format!("first definition of {} `{}` here",
 224                                       namespace_error_to_string(duplicate_type),
 225                                       name));
 226                         }
 227                     }
 228                 }
 229                 child
 230             }
 231         }
 232     }
 233
 234     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 235         // Check each statement.
 236         for statement in &block.stmts {
 237             match statement.node {
 238                 StmtDecl(ref declaration, _) => {
 239                     match declaration.node {
 240                         DeclItem(_) => {
 241                             return true;
 242                         }
 243                         _ => {
 244                             // Keep searching.
 245                         }
 246                     }
 247                 }
 248                 _ => {
 249                     // Keep searching.
 250                 }
 251             }
 252         }
 253
 254         // If we found no items, we don't need to create
 255         // an anonymous module.
 256
 257         return false;
 258     }
 259
 260     fn get_parent_link(&mut self, parent: &Rc<Module>, name: Name) -> ParentLink {
 261         ModuleParentLink(Rc::downgrade(parent), name)
 262     }
 263
 264     /// Constructs the reduced graph for one item.
 265     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: &Rc<Module>) -> Rc<Module> {
 266         let name = item.name;
 267         let sp = item.span;
 268         let is_public = item.vis == hir::Public;
 269         let modifiers = if is_public {
 270             DefModifiers::PUBLIC
 271         } else {
 272             DefModifiers::empty()
 273         } | DefModifiers::IMPORTABLE;
 274
 275         match item.node {
 276             ItemUse(ref view_path) => {
 277                 // Extract and intern the module part of the path. For
 278                 // globs and lists, the path is found directly in the AST;
 279                 // for simple paths we have to munge the path a little.
 280                 let module_path = match view_path.node {
 281                     ViewPathSimple(_, ref full_path) => {
 282                         full_path.segments
 283                             .split_last().unwrap().1
 284                             .iter().map(|seg| seg.identifier.name)
 285                             .collect()
 286                     }
 287
 288                     ViewPathGlob(ref module_ident_path) |
 289                     ViewPathList(ref module_ident_path, _) => {
 290                         module_ident_path.segments
 291                             .iter().map(|seg| seg.identifier.name).collect()
 292                     }
 293                 };
 294
 295                 // Build up the import directives.
 296                 let shadowable = item.attrs.iter().any(|attr| {
 297                     attr.name() == special_idents::prelude_import.name.as_str()
 298                 });
 299                 let shadowable = if shadowable {
 300                     Shadowable::Always
 301                 } else {
 302                     Shadowable::Never
 303                 };
 304
 305                 match view_path.node {
 306                     ViewPathSimple(binding, ref full_path) => {
 307                         let source_name =
 308                             full_path.segments.last().unwrap().identifier.name;
 309                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 310                             resolve_error(self,
 311                                           view_path.span,
 312                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 313                         }
 314
 315                         let subclass = SingleImport(binding, source_name);
 316                         self.build_import_directive(&**parent,
 317                                                     module_path,
 318                                                     subclass,
 319                                                     view_path.span,
 320                                                     item.id,
 321                                                     is_public,
 322                                                     shadowable);
 323                     }
 324                     ViewPathList(_, ref source_items) => {
 325                         // Make sure there's at most one `mod` import in the list.
 326                         let mod_spans = source_items.iter().filter_map(|item| match item.node {
 327                             PathListMod { .. } => Some(item.span),
 328                             _ => None
 329                         }).collect::<Vec<Span>>();
 330                         if mod_spans.len() > 1 {
 331                             resolve_error(
 332                                 self,
 333                                 mod_spans[0],
 334                                 ResolutionError::SelfImportCanOnlyAppearOnceInTheList
 335                             );
 336                             for other_span in mod_spans.iter().skip(1) {
 337                                 self.session.span_note(*other_span,
 338                                     "another `self` import appears here");
 339                             }
 340                         }
 341
 342                         for source_item in source_items {
 343                             let (module_path, name, rename) = match source_item.node {
 344                                 PathListIdent { name, rename, .. } =>
 345                                     (module_path.clone(), name, rename.unwrap_or(name)),
 346                                 PathListMod { rename, .. } => {
 347                                     let name = match module_path.last() {
 348                                         Some(name) => *name,
 349                                         None => {
 350                                             resolve_error(
 351                                                 self,
 352                                                 source_item.span,
 353                                                 ResolutionError::
 354                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 355                                             );
 356                                             continue;
 357                                         }
 358                                     };
 359                                     let module_path = module_path.split_last().unwrap().1;
 360                                     let rename = rename.unwrap_or(name);
 361                                     (module_path.to_vec(), name, rename)
 362                                 }
 363                             };
 364                             self.build_import_directive(
 365                                 &**parent,
 366                                 module_path,
 367                                 SingleImport(rename, name),
 368                                 source_item.span,
 369                                 source_item.node.id(),
 370                                 is_public,
 371                                 shadowable);
 372                         }
 373                     }
 374                     ViewPathGlob(_) => {
 375                         self.build_import_directive(&**parent,
 376                                                     module_path,
 377                                                     GlobImport,
 378                                                     view_path.span,
 379                                                     item.id,
 380                                                     is_public,
 381                                                     shadowable);
 382                     }
 383                 }
 384                 parent.clone()
 385             }
 386
 387             ItemExternCrate(_) => {
 388                 // n.b. we don't need to look at the path option here, because cstore already did
 389                 if let Some(crate_id) = self.session.cstore.find_extern_mod_stmt_cnum(item.id) {
 390                     let def_id = DefId { krate: crate_id, node: 0 };
 391                     self.external_exports.insert(def_id);
 392                     let parent_link = ModuleParentLink(Rc::downgrade(parent), name);
 393                     let external_module = Rc::new(Module::new(parent_link,
 394                                                               Some(def_id),
 395                                                               NormalModuleKind,
 396                                                               false,
 397                                                               true));
 398                     debug!("(build reduced graph for item) found extern `{}`",
 399                             module_to_string(&*external_module));
 400                     self.check_for_conflicts_between_external_crates(&**parent, name, sp);
 401                     parent.external_module_children.borrow_mut()
 402                           .insert(name, external_module.clone());
 403                     self.build_reduced_graph_for_external_crate(&external_module);
 404                 }
 405                 parent.clone()
 406             }
 407
 408             ItemMod(..) => {
 409                 let name_bindings = self.add_child(name, parent, ForbidDuplicateModules, sp);
 410
 411                 let parent_link = self.get_parent_link(parent, name);
 412                 let def_id = DefId { krate: 0, node: item.id };
 413                 name_bindings.define_module(parent_link,
 414                                             Some(def_id),
 415                                             NormalModuleKind,
 416                                             false,
 417                                             is_public,
 418                                             sp);
 419
 420                 name_bindings.get_module()
 421             }
 422
 423             ItemForeignMod(..) => parent.clone(),
 424
 425             // These items live in the value namespace.
 426             ItemStatic(_, m, _) => {
 427                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 428                 let mutbl = m == hir::MutMutable;
 429
 430                 name_bindings.define_value(DefStatic(DefId::local(item.id), mutbl), sp, modifiers);
 431                 parent.clone()
 432             }
 433             ItemConst(_, _) => {
 434                 self.add_child(name, parent, ForbidDuplicateValues, sp)
 435                     .define_value(DefConst(DefId::local(item.id)), sp, modifiers);
 436                 parent.clone()
 437             }
 438             ItemFn(_, _, _, _, _, _) => {
 439                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 440
 441                 let def = DefFn(DefId::local(item.id), false);
 442                 name_bindings.define_value(def, sp, modifiers);
 443                 parent.clone()
 444             }
 445
 446             // These items live in the type namespace.
 447             ItemTy(..) => {
 448                 let name_bindings =
 449                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 450
 451                 name_bindings.define_type(DefTy(DefId::local(item.id), false), sp,
 452                                           modifiers);
 453
 454                 let parent_link = self.get_parent_link(parent, name);
 455                 name_bindings.set_module_kind(parent_link,
 456                                               Some(DefId::local(item.id)),
 457                                               TypeModuleKind,
 458                                               false,
 459                                               is_public,
 460                                               sp);
 461                 parent.clone()
 462             }
 463
 464             ItemEnum(ref enum_definition, _) => {
 465                 let name_bindings =
 466                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 467
 468                 name_bindings.define_type(DefTy(DefId::local(item.id), true), sp, modifiers);
 469
 470                 let parent_link = self.get_parent_link(parent, name);
 471                 name_bindings.set_module_kind(parent_link,
 472                                               Some(DefId::local(item.id)),
 473                                               EnumModuleKind,
 474                                               false,
 475                                               is_public,
 476                                               sp);
 477
 478                 let module = name_bindings.get_module();
 479
 480                 for variant in &(*enum_definition).variants {
 481                     self.build_reduced_graph_for_variant(
 482                         &**variant,
 483                         DefId::local(item.id),
 484                         &module);
 485                 }
 486                 parent.clone()
 487             }
 488
 489             // These items live in both the type and value namespaces.
 490             ItemStruct(ref struct_def, _) => {
 491                 // Adding to both Type and Value namespaces or just Type?
 492                 let (forbid, ctor_id) = match struct_def.ctor_id {
 493                     Some(ctor_id)   => (ForbidDuplicateTypesAndValues, Some(ctor_id)),
 494                     None            => (ForbidDuplicateTypesAndModules, None)
 495                 };
 496
 497                 let name_bindings = self.add_child(name, parent, forbid, sp);
 498
 499                 // Define a name in the type namespace.
 500                 name_bindings.define_type(DefTy(DefId::local(item.id), false), sp, modifiers);
 501
 502                 // If this is a newtype or unit-like struct, define a name
 503                 // in the value namespace as well
 504                 if let Some(cid) = ctor_id {
 505                     name_bindings.define_value(DefStruct(DefId::local(cid)), sp, modifiers);
 506                 }
 507
 508                 // Record the def ID and fields of this struct.
 509                 let named_fields = struct_def.fields.iter().filter_map(|f| {
 510                     match f.node.kind {
 511                         NamedField(name, _) => Some(name),
 512                         UnnamedField(_) => None
 513                     }
 514                 }).collect();
 515                 self.structs.insert(DefId::local(item.id), named_fields);
 516
 517                 parent.clone()
 518             }
 519
 520             ItemDefaultImpl(_, _) |
 521             ItemImpl(..) => parent.clone(),
 522
 523             ItemTrait(_, _, _, ref items) => {
 524                 let name_bindings =
 525                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 526
 527                 // Add all the items within to a new module.
 528                 let parent_link = self.get_parent_link(parent, name);
 529                 name_bindings.define_module(parent_link,
 530                                             Some(DefId::local(item.id)),
 531                                             TraitModuleKind,
 532                                             false,
 533                                             is_public,
 534                                             sp);
 535                 let module_parent = name_bindings.get_module();
 536
 537                 let def_id = DefId::local(item.id);
 538
 539                 // Add the names of all the items to the trait info.
 540                 for trait_item in items {
 541                     let name_bindings = self.add_child(trait_item.name,
 542                                         &module_parent,
 543                                         ForbidDuplicateTypesAndValues,
 544                                         trait_item.span);
 545
 546                     match trait_item.node {
 547                         hir::ConstTraitItem(..) => {
 548                             let def = DefAssociatedConst(DefId::local(trait_item.id));
 549                             // NB: not DefModifiers::IMPORTABLE
 550                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 551                         }
 552                         hir::MethodTraitItem(..) => {
 553                             let def = DefMethod(DefId::local(trait_item.id));
 554                             // NB: not DefModifiers::IMPORTABLE
 555                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 556                         }
 557                         hir::TypeTraitItem(..) => {
 558                             let def = DefAssociatedTy(DefId::local(item.id),
 559                                                       DefId::local(trait_item.id));
 560                             // NB: not DefModifiers::IMPORTABLE
 561                             name_bindings.define_type(def, trait_item.span, DefModifiers::PUBLIC);
 562                         }
 563                     }
 564
 565                     self.trait_item_map.insert((trait_item.name, def_id),
 566                                                DefId::local(trait_item.id));
 567                 }
 568
 569                 name_bindings.define_type(DefTrait(def_id), sp, modifiers);
 570                 parent.clone()
 571             }
 572         }
 573     }
 574
 575     // Constructs the reduced graph for one variant. Variants exist in the
 576     // type and value namespaces.
 577     fn build_reduced_graph_for_variant(&mut self,
 578                                        variant: &Variant,
 579                                        item_id: DefId,
 580                                        parent: &Rc<Module>) {
 581         let name = variant.node.name;
 582         let is_exported = match variant.node.kind {
 583             TupleVariantKind(_) => false,
 584             StructVariantKind(_) => {
 585                 // Not adding fields for variants as they are not accessed with a self receiver
 586                 self.structs.insert(DefId::local(variant.node.id), Vec::new());
 587                 true
 588             }
 589         };
 590
 591         let child = self.add_child(name, parent,
 592                                    ForbidDuplicateTypesAndValues,
 593                                    variant.span);
 594         // variants are always treated as importable to allow them to be glob
 595         // used
 596         child.define_value(DefVariant(item_id,
 597                                       DefId::local(variant.node.id), is_exported),
 598                            variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 599         child.define_type(DefVariant(item_id,
 600                                      DefId::local(variant.node.id), is_exported),
 601                           variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 602     }
 603
 604     /// Constructs the reduced graph for one foreign item.
 605     fn build_reduced_graph_for_foreign_item(&mut self,
 606                                             foreign_item: &ForeignItem,
 607                                             parent: &Rc<Module>) {
 608         let name = foreign_item.name;
 609         let is_public = foreign_item.vis == hir::Public;
 610         let modifiers = if is_public {
 611             DefModifiers::PUBLIC
 612         } else {
 613             DefModifiers::empty()
 614         } | DefModifiers::IMPORTABLE;
 615         let name_bindings =
 616             self.add_child(name, parent, ForbidDuplicateValues,
 617                            foreign_item.span);
 618
 619         let def = match foreign_item.node {
 620             ForeignItemFn(..) => {
 621                 DefFn(DefId::local(foreign_item.id), false)
 622             }
 623             ForeignItemStatic(_, m) => {
 624                 DefStatic(DefId::local(foreign_item.id), m)
 625             }
 626         };
 627         name_bindings.define_value(def, foreign_item.span, modifiers);
 628     }
 629
 630     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &Rc<Module>) -> Rc<Module> {
 631         if self.block_needs_anonymous_module(block) {
 632             let block_id = block.id;
 633
 634             debug!("(building reduced graph for block) creating a new \
 635                     anonymous module for block {}",
 636                    block_id);
 637
 638             let new_module = Rc::new(Module::new(
 639                 BlockParentLink(Rc::downgrade(parent), block_id),
 640                 None,
 641                 AnonymousModuleKind,
 642                 false,
 643                 false));
 644             parent.anonymous_children.borrow_mut().insert(block_id, new_module.clone());
 645             new_module
 646         } else {
 647             parent.clone()
 648         }
 649     }
 650
 651     fn handle_external_def(&mut self,
 652                            def: Def,
 653                            vis: Visibility,
 654                            child_name_bindings: &NameBindings,
 655                            final_ident: &str,
 656                            name: Name,
 657                            new_parent: &Rc<Module>) {
 658         debug!("(building reduced graph for \
 659                 external crate) building external def {}, priv {:?}",
 660                final_ident, vis);
 661         let is_public = vis == hir::Public;
 662         let modifiers = if is_public {
 663             DefModifiers::PUBLIC
 664         } else {
 665             DefModifiers::empty()
 666         } | DefModifiers::IMPORTABLE;
 667         let is_exported = is_public && match new_parent.def_id.get() {
 668             None => true,
 669             Some(did) => self.external_exports.contains(&did)
 670         };
 671         if is_exported {
 672             self.external_exports.insert(def.def_id());
 673         }
 674
 675         let kind = match def {
 676             DefTy(_, true) => EnumModuleKind,
 677             DefTy(_, false) | DefStruct(..) => TypeModuleKind,
 678             _ => NormalModuleKind
 679         };
 680
 681         match def {
 682           DefMod(def_id) | DefForeignMod(def_id) | DefStruct(def_id) |
 683           DefTy(def_id, _) => {
 684             let type_def = child_name_bindings.type_def.borrow().clone();
 685             match type_def {
 686               Some(TypeNsDef { module_def: Some(module_def), .. }) => {
 687                 debug!("(building reduced graph for external crate) \
 688                         already created module");
 689                 module_def.def_id.set(Some(def_id));
 690               }
 691               Some(_) | None => {
 692                 debug!("(building reduced graph for \
 693                         external crate) building module \
 694                         {} {}", final_ident, is_public);
 695                 let parent_link = self.get_parent_link(new_parent, name);
 696
 697                 child_name_bindings.define_module(parent_link,
 698                                                   Some(def_id),
 699                                                   kind,
 700                                                   true,
 701                                                   is_public,
 702                                                   DUMMY_SP);
 703               }
 704             }
 705           }
 706           _ => {}
 707         }
 708
 709         match def {
 710           DefMod(_) | DefForeignMod(_) => {}
 711           DefVariant(_, variant_id, is_struct) => {
 712               debug!("(building reduced graph for external crate) building \
 713                       variant {}",
 714                       final_ident);
 715               // variants are always treated as importable to allow them to be
 716               // glob used
 717               let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 718               if is_struct {
 719                   child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 720                   // Not adding fields for variants as they are not accessed with a self receiver
 721                   self.structs.insert(variant_id, Vec::new());
 722               } else {
 723                   child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 724               }
 725           }
 726           DefFn(ctor_id, true) => {
 727             child_name_bindings.define_value(
 728                 csearch::get_tuple_struct_definition_if_ctor(&self.session.cstore, ctor_id)
 729                     .map_or(def, |_| DefStruct(ctor_id)), DUMMY_SP, modifiers);
 730           }
 731           DefFn(..) | DefStatic(..) | DefConst(..) | DefAssociatedConst(..) |
 732           DefMethod(..) => {
 733             debug!("(building reduced graph for external \
 734                     crate) building value (fn/static) {}", final_ident);
 735             // impl methods have already been defined with the correct importability modifier
 736             let mut modifiers = match *child_name_bindings.value_def.borrow() {
 737                 Some(ref def) => (modifiers & !DefModifiers::IMPORTABLE) |
 738                              (def.modifiers &  DefModifiers::IMPORTABLE),
 739                 None => modifiers
 740             };
 741             if new_parent.kind.get() != NormalModuleKind {
 742                 modifiers = modifiers & !DefModifiers::IMPORTABLE;
 743             }
 744             child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 745           }
 746           DefTrait(def_id) => {
 747               debug!("(building reduced graph for external \
 748                       crate) building type {}", final_ident);
 749
 750               // If this is a trait, add all the trait item names to the trait
 751               // info.
 752
 753               let trait_item_def_ids =
 754                 csearch::get_trait_item_def_ids(&self.session.cstore, def_id);
 755               for trait_item_def in &trait_item_def_ids {
 756                   let trait_item_name = csearch::get_trait_name(&self.session.cstore,
 757                                                                 trait_item_def.def_id());
 758
 759                   debug!("(building reduced graph for external crate) ... \
 760                           adding trait item '{}'",
 761                          trait_item_name);
 762
 763                   self.trait_item_map.insert((trait_item_name, def_id),
 764                                              trait_item_def.def_id());
 765
 766                   if is_exported {
 767                       self.external_exports.insert(trait_item_def.def_id());
 768                   }
 769               }
 770
 771               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 772
 773               // Define a module if necessary.
 774               let parent_link = self.get_parent_link(new_parent, name);
 775               child_name_bindings.set_module_kind(parent_link,
 776                                                   Some(def_id),
 777                                                   TraitModuleKind,
 778                                                   true,
 779                                                   is_public,
 780                                                   DUMMY_SP)
 781           }
 782           DefTy(..) | DefAssociatedTy(..) => {
 783               debug!("(building reduced graph for external \
 784                       crate) building type {}", final_ident);
 785
 786               let modifiers = match new_parent.kind.get() {
 787                   NormalModuleKind => modifiers,
 788                   _ => modifiers & !DefModifiers::IMPORTABLE
 789               };
 790
 791               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 792           }
 793           DefStruct(def_id) => {
 794             debug!("(building reduced graph for external \
 795                     crate) building type and value for {}",
 796                    final_ident);
 797             child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 798             let fields = csearch::get_struct_field_names(&self.session.cstore, def_id);
 799
 800             if fields.is_empty() {
 801                 child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 802             }
 803
 804             // Record the def ID and fields of this struct.
 805             self.structs.insert(def_id, fields);
 806           }
 807           DefLocal(..) | DefPrimTy(..) | DefTyParam(..) |
 808           DefUse(..) | DefUpvar(..) | DefRegion(..) |
 809           DefLabel(..) | DefSelfTy(..) => {
 810             panic!("didn't expect `{:?}`", def);
 811           }
 812         }
 813     }
 814
 815     /// Builds the reduced graph for a single item in an external crate.
 816     fn build_reduced_graph_for_external_crate_def(&mut self,
 817                                                   root: &Rc<Module>,
 818                                                   def_like: DefLike,
 819                                                   name: Name,
 820                                                   def_visibility: Visibility) {
 821         match def_like {
 822             DlDef(def) => {
 823                 // Add the new child item, if necessary.
 824                 match def {
 825                     DefForeignMod(def_id) => {
 826                         // Foreign modules have no names. Recur and populate
 827                         // eagerly.
 828                         csearch::each_child_of_item(&self.session.cstore,
 829                                                     def_id,
 830                                                     |def_like,
 831                                                      child_name,
 832                                                      vis| {
 833                             self.build_reduced_graph_for_external_crate_def(
 834                                 root,
 835                                 def_like,
 836                                 child_name,
 837                                 vis)
 838                         });
 839                     }
 840                     _ => {
 841                         let child_name_bindings =
 842                             self.add_child(name,
 843                                            root,
 844                                            OverwriteDuplicates,
 845                                            DUMMY_SP);
 846
 847                         self.handle_external_def(def,
 848                                                  def_visibility,
 849                                                  &*child_name_bindings,
 850                                                  &name.as_str(),
 851                                                  name,
 852                                                  root);
 853                     }
 854                 }
 855             }
 856             DlImpl(_) => {
 857                 debug!("(building reduced graph for external crate) \
 858                         ignoring impl");
 859             }
 860             DlField => {
 861                 debug!("(building reduced graph for external crate) \
 862                         ignoring field");
 863             }
 864         }
 865     }
 866
 867     /// Builds the reduced graph rooted at the given external module.
 868     fn populate_external_module(&mut self, module: &Rc<Module>) {
 869         debug!("(populating external module) attempting to populate {}",
 870                module_to_string(&**module));
 871
 872         let def_id = match module.def_id.get() {
 873             None => {
 874                 debug!("(populating external module) ... no def ID!");
 875                 return
 876             }
 877             Some(def_id) => def_id,
 878         };
 879
 880         csearch::each_child_of_item(&self.session.cstore,
 881                                     def_id,
 882                                     |def_like, child_name, visibility| {
 883             debug!("(populating external module) ... found ident: {}",
 884                    child_name);
 885             self.build_reduced_graph_for_external_crate_def(module,
 886                                                             def_like,
 887                                                             child_name,
 888                                                             visibility)
 889         });
 890         module.populated.set(true)
 891     }
 892
 893     /// Ensures that the reduced graph rooted at the given external module
 894     /// is built, building it if it is not.
 895     fn populate_module_if_necessary(&mut self, module: &Rc<Module>) {
 896         if !module.populated.get() {
 897             self.populate_external_module(module)
 898         }
 899         assert!(module.populated.get())
 900     }
 901
 902     /// Builds the reduced graph rooted at the 'use' directive for an external
 903     /// crate.
 904     fn build_reduced_graph_for_external_crate(&mut self, root: &Rc<Module>) {
 905         csearch::each_top_level_item_of_crate(&self.session.cstore,
 906                                               root.def_id
 907                                                   .get()
 908                                                   .unwrap()
 909                                                   .krate,
 910                                               |def_like, name, visibility| {
 911             self.build_reduced_graph_for_external_crate_def(root, def_like, name, visibility)
 912         });
 913     }
 914
 915     /// Creates and adds an import directive to the given module.
 916     fn build_import_directive(&mut self,
 917                               module_: &Module,
 918                               module_path: Vec<Name>,
 919                               subclass: ImportDirectiveSubclass,
 920                               span: Span,
 921                               id: NodeId,
 922                               is_public: bool,
 923                               shadowable: Shadowable) {
 924         module_.imports.borrow_mut().push(ImportDirective::new(module_path,
 925                                                                subclass,
 926                                                                span,
 927                                                                id,
 928                                                                is_public,
 929                                                                shadowable));
 930         self.unresolved_imports += 1;
 931
 932         if is_public {
 933             module_.inc_pub_count();
 934         }
 935
 936         // Bump the reference count on the name. Or, if this is a glob, set
 937         // the appropriate flag.
 938
 939         match subclass {
 940             SingleImport(target, _) => {
 941                 debug!("(building import directive) building import directive: {}::{}",
 942                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 943                        target);
 944
 945                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 946                 match import_resolutions.get_mut(&target) {
 947                     Some(resolution) => {
 948                         debug!("(building import directive) bumping reference");
 949                         resolution.outstanding_references += 1;
 950
 951                         // the source of this name is different now
 952                         resolution.type_id = id;
 953                         resolution.value_id = id;
 954                         resolution.is_public = is_public;
 955                         return;
 956                     }
 957                     None => {}
 958                 }
 959                 debug!("(building import directive) creating new");
 960                 let mut resolution = ImportResolution::new(id, is_public);
 961                 resolution.outstanding_references = 1;
 962                 import_resolutions.insert(target, resolution);
 963             }
 964             GlobImport => {
 965                 // Set the glob flag. This tells us that we don't know the
 966                 // module's exports ahead of time.
 967
 968                 module_.inc_glob_count();
 969                 if is_public {
 970                     module_.inc_pub_glob_count();
 971                 }
 972             }
 973         }
 974     }
 975 }
 976
 977 struct BuildReducedGraphVisitor<'a, 'b:'a, 'tcx:'b> {
 978     builder: GraphBuilder<'a, 'b, 'tcx>,
 979     parent: Rc<Module>
 980 }
 981
 982 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 983     fn visit_item(&mut self, item: &Item) {
 984         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 985         let old_parent = replace(&mut self.parent, p);
 986         visit::walk_item(self, item);
 987         self.parent = old_parent;
 988     }
 989
 990     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 991         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 992     }
 993
 994     fn visit_block(&mut self, block: &Block) {
 995         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 996         let old_parent = replace(&mut self.parent, np);
 997         visit::walk_block(self, block);
 998         self.parent = old_parent;
 999     }
1000 }
1001
1002 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &hir::Crate) {
1003     GraphBuilder {
1004         resolver: resolver
1005     }.build_reduced_graph(krate);
1006 }
1007
1008 pub fn populate_module_if_necessary(resolver: &mut Resolver, module: &Rc<Module>) {
1009     GraphBuilder {
1010         resolver: resolver
1011     }.populate_module_if_necessary(module);
1012 }