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
  38 use syntax::ast::{Block, Crate};
  39 use syntax::ast::{DeclItem, DefId};
  40 use syntax::ast::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  41 use syntax::ast::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  42 use syntax::ast::{ItemForeignMod, ItemImpl, ItemMac, ItemMod, ItemStatic, ItemDefaultImpl};
  43 use syntax::ast::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  44 use syntax::ast::{Name, NamedField, NodeId};
  45 use syntax::ast::{PathListIdent, PathListMod, Public};
  46 use syntax::ast::StmtDecl;
  47 use syntax::ast::StructVariantKind;
  48 use syntax::ast::TupleVariantKind;
  49 use syntax::ast::UnnamedField;
  50 use syntax::ast::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  51 use syntax::ast::Visibility;
  52 use syntax::ast;
  53 use syntax::ast_util::local_def;
  54 use syntax::attr::AttrMetaMethods;
  55 use syntax::parse::token::special_idents;
  56 use syntax::codemap::{Span, DUMMY_SP};
  57 use syntax::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: &ast::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.ident.name;
 267         let sp = item.span;
 268         let is_public = item.vis == ast::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(|ident| ident.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(|ident| ident.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.name,
 316                                                     source_name);
 317                         self.build_import_directive(&**parent,
 318                                                     module_path,
 319                                                     subclass,
 320                                                     view_path.span,
 321                                                     item.id,
 322                                                     is_public,
 323                                                     shadowable);
 324                     }
 325                     ViewPathList(_, ref source_items) => {
 326                         // Make sure there's at most one `mod` import in the list.
 327                         let mod_spans = source_items.iter().filter_map(|item| match item.node {
 328                             PathListMod { .. } => Some(item.span),
 329                             _ => None
 330                         }).collect::<Vec<Span>>();
 331                         if mod_spans.len() > 1 {
 332                             resolve_error(
 333                                 self,
 334                                 mod_spans[0],
 335                                 ResolutionError::SelfImportCanOnlyAppearOnceInTheList
 336                             );
 337                             for other_span in mod_spans.iter().skip(1) {
 338                                 self.session.span_note(*other_span,
 339                                     "another `self` import appears here");
 340                             }
 341                         }
 342
 343                         for source_item in source_items {
 344                             let (module_path, name, rename) = match source_item.node {
 345                                 PathListIdent { name, rename, .. } =>
 346                                     (module_path.clone(), name.name, rename.unwrap_or(name).name),
 347                                 PathListMod { rename, .. } => {
 348                                     let name = match module_path.last() {
 349                                         Some(name) => *name,
 350                                         None => {
 351                                             resolve_error(
 352                                                 self,
 353                                                 source_item.span,
 354                                                 ResolutionError::
 355                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 356                                             );
 357                                             continue;
 358                                         }
 359                                     };
 360                                     let module_path = module_path.split_last().unwrap().1;
 361                                     let rename = rename.map(|n| n.name).unwrap_or(name);
 362                                     (module_path.to_vec(), name, rename)
 363                                 }
 364                             };
 365                             self.build_import_directive(
 366                                 &**parent,
 367                                 module_path,
 368                                 SingleImport(rename, name),
 369                                 source_item.span,
 370                                 source_item.node.id(),
 371                                 is_public,
 372                                 shadowable);
 373                         }
 374                     }
 375                     ViewPathGlob(_) => {
 376                         self.build_import_directive(&**parent,
 377                                                     module_path,
 378                                                     GlobImport,
 379                                                     view_path.span,
 380                                                     item.id,
 381                                                     is_public,
 382                                                     shadowable);
 383                     }
 384                 }
 385                 parent.clone()
 386             }
 387
 388             ItemExternCrate(_) => {
 389                 // n.b. we don't need to look at the path option here, because cstore already did
 390                 if let Some(crate_id) = self.session.cstore.find_extern_mod_stmt_cnum(item.id) {
 391                     let def_id = DefId { krate: crate_id, node: 0 };
 392                     self.external_exports.insert(def_id);
 393                     let parent_link = ModuleParentLink(Rc::downgrade(parent), name);
 394                     let external_module = Rc::new(Module::new(parent_link,
 395                                                               Some(def_id),
 396                                                               NormalModuleKind,
 397                                                               false,
 398                                                               true));
 399                     debug!("(build reduced graph for item) found extern `{}`",
 400                             module_to_string(&*external_module));
 401                     self.check_for_conflicts_between_external_crates(&**parent, name, sp);
 402                     parent.external_module_children.borrow_mut()
 403                           .insert(name, external_module.clone());
 404                     self.build_reduced_graph_for_external_crate(&external_module);
 405                 }
 406                 parent.clone()
 407             }
 408
 409             ItemMod(..) => {
 410                 let name_bindings = self.add_child(name, parent, ForbidDuplicateModules, sp);
 411
 412                 let parent_link = self.get_parent_link(parent, name);
 413                 let def_id = DefId { krate: 0, node: item.id };
 414                 name_bindings.define_module(parent_link,
 415                                             Some(def_id),
 416                                             NormalModuleKind,
 417                                             false,
 418                                             is_public,
 419                                             sp);
 420
 421                 name_bindings.get_module()
 422             }
 423
 424             ItemForeignMod(..) => parent.clone(),
 425
 426             // These items live in the value namespace.
 427             ItemStatic(_, m, _) => {
 428                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 429                 let mutbl = m == ast::MutMutable;
 430
 431                 name_bindings.define_value(DefStatic(local_def(item.id), mutbl), sp, modifiers);
 432                 parent.clone()
 433             }
 434             ItemConst(_, _) => {
 435                 self.add_child(name, parent, ForbidDuplicateValues, sp)
 436                     .define_value(DefConst(local_def(item.id)), sp, modifiers);
 437                 parent.clone()
 438             }
 439             ItemFn(_, _, _, _, _, _) => {
 440                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 441
 442                 let def = DefFn(local_def(item.id), false);
 443                 name_bindings.define_value(def, sp, modifiers);
 444                 parent.clone()
 445             }
 446
 447             // These items live in the type namespace.
 448             ItemTy(..) => {
 449                 let name_bindings =
 450                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 451
 452                 name_bindings.define_type(DefTy(local_def(item.id), false), sp,
 453                                           modifiers);
 454
 455                 let parent_link = self.get_parent_link(parent, name);
 456                 name_bindings.set_module_kind(parent_link,
 457                                               Some(local_def(item.id)),
 458                                               TypeModuleKind,
 459                                               false,
 460                                               is_public,
 461                                               sp);
 462                 parent.clone()
 463             }
 464
 465             ItemEnum(ref enum_definition, _) => {
 466                 let name_bindings =
 467                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 468
 469                 name_bindings.define_type(DefTy(local_def(item.id), true), sp, modifiers);
 470
 471                 let parent_link = self.get_parent_link(parent, name);
 472                 name_bindings.set_module_kind(parent_link,
 473                                               Some(local_def(item.id)),
 474                                               EnumModuleKind,
 475                                               false,
 476                                               is_public,
 477                                               sp);
 478
 479                 let module = name_bindings.get_module();
 480
 481                 for variant in &(*enum_definition).variants {
 482                     self.build_reduced_graph_for_variant(
 483                         &**variant,
 484                         local_def(item.id),
 485                         &module);
 486                 }
 487                 parent.clone()
 488             }
 489
 490             // These items live in both the type and value namespaces.
 491             ItemStruct(ref struct_def, _) => {
 492                 // Adding to both Type and Value namespaces or just Type?
 493                 let (forbid, ctor_id) = match struct_def.ctor_id {
 494                     Some(ctor_id)   => (ForbidDuplicateTypesAndValues, Some(ctor_id)),
 495                     None            => (ForbidDuplicateTypesAndModules, None)
 496                 };
 497
 498                 let name_bindings = self.add_child(name, parent, forbid, sp);
 499
 500                 // Define a name in the type namespace.
 501                 name_bindings.define_type(DefTy(local_def(item.id), false), sp, modifiers);
 502
 503                 // If this is a newtype or unit-like struct, define a name
 504                 // in the value namespace as well
 505                 if let Some(cid) = ctor_id {
 506                     name_bindings.define_value(DefStruct(local_def(cid)), sp, modifiers);
 507                 }
 508
 509                 // Record the def ID and fields of this struct.
 510                 let named_fields = struct_def.fields.iter().filter_map(|f| {
 511                     match f.node.kind {
 512                         NamedField(ident, _) => Some(ident.name),
 513                         UnnamedField(_) => None
 514                     }
 515                 }).collect();
 516                 self.structs.insert(local_def(item.id), named_fields);
 517
 518                 parent.clone()
 519             }
 520
 521             ItemDefaultImpl(_, _) |
 522             ItemImpl(..) => parent.clone(),
 523
 524             ItemTrait(_, _, _, ref items) => {
 525                 let name_bindings =
 526                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 527
 528                 // Add all the items within to a new module.
 529                 let parent_link = self.get_parent_link(parent, name);
 530                 name_bindings.define_module(parent_link,
 531                                             Some(local_def(item.id)),
 532                                             TraitModuleKind,
 533                                             false,
 534                                             is_public,
 535                                             sp);
 536                 let module_parent = name_bindings.get_module();
 537
 538                 let def_id = local_def(item.id);
 539
 540                 // Add the names of all the items to the trait info.
 541                 for trait_item in items {
 542                     let name_bindings = self.add_child(trait_item.ident.name,
 543                                         &module_parent,
 544                                         ForbidDuplicateTypesAndValues,
 545                                         trait_item.span);
 546
 547                     match trait_item.node {
 548                         ast::ConstTraitItem(..) => {
 549                             let def = DefAssociatedConst(local_def(trait_item.id));
 550                             // NB: not DefModifiers::IMPORTABLE
 551                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 552                         }
 553                         ast::MethodTraitItem(..) => {
 554                             let def = DefMethod(local_def(trait_item.id));
 555                             // NB: not DefModifiers::IMPORTABLE
 556                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 557                         }
 558                         ast::TypeTraitItem(..) => {
 559                             let def = DefAssociatedTy(local_def(item.id),
 560                                                       local_def(trait_item.id));
 561                             // NB: not DefModifiers::IMPORTABLE
 562                             name_bindings.define_type(def, trait_item.span, DefModifiers::PUBLIC);
 563                         }
 564                     }
 565
 566                     self.trait_item_map.insert((trait_item.ident.name, def_id),
 567                                                local_def(trait_item.id));
 568                 }
 569
 570                 name_bindings.define_type(DefTrait(def_id), sp, modifiers);
 571                 parent.clone()
 572             }
 573             ItemMac(..) => parent.clone()
 574         }
 575     }
 576
 577     // Constructs the reduced graph for one variant. Variants exist in the
 578     // type and value namespaces.
 579     fn build_reduced_graph_for_variant(&mut self,
 580                                        variant: &Variant,
 581                                        item_id: DefId,
 582                                        parent: &Rc<Module>) {
 583         let name = variant.node.name.name;
 584         let is_exported = match variant.node.kind {
 585             TupleVariantKind(_) => false,
 586             StructVariantKind(_) => {
 587                 // Not adding fields for variants as they are not accessed with a self receiver
 588                 self.structs.insert(local_def(variant.node.id), Vec::new());
 589                 true
 590             }
 591         };
 592
 593         let child = self.add_child(name, parent,
 594                                    ForbidDuplicateTypesAndValues,
 595                                    variant.span);
 596         // variants are always treated as importable to allow them to be glob
 597         // used
 598         child.define_value(DefVariant(item_id,
 599                                       local_def(variant.node.id), is_exported),
 600                            variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 601         child.define_type(DefVariant(item_id,
 602                                      local_def(variant.node.id), is_exported),
 603                           variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 604     }
 605
 606     /// Constructs the reduced graph for one foreign item.
 607     fn build_reduced_graph_for_foreign_item(&mut self,
 608                                             foreign_item: &ForeignItem,
 609                                             parent: &Rc<Module>) {
 610         let name = foreign_item.ident.name;
 611         let is_public = foreign_item.vis == ast::Public;
 612         let modifiers = if is_public {
 613             DefModifiers::PUBLIC
 614         } else {
 615             DefModifiers::empty()
 616         } | DefModifiers::IMPORTABLE;
 617         let name_bindings =
 618             self.add_child(name, parent, ForbidDuplicateValues,
 619                            foreign_item.span);
 620
 621         let def = match foreign_item.node {
 622             ForeignItemFn(..) => {
 623                 DefFn(local_def(foreign_item.id), false)
 624             }
 625             ForeignItemStatic(_, m) => {
 626                 DefStatic(local_def(foreign_item.id), m)
 627             }
 628         };
 629         name_bindings.define_value(def, foreign_item.span, modifiers);
 630     }
 631
 632     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &Rc<Module>) -> Rc<Module> {
 633         if self.block_needs_anonymous_module(block) {
 634             let block_id = block.id;
 635
 636             debug!("(building reduced graph for block) creating a new \
 637                     anonymous module for block {}",
 638                    block_id);
 639
 640             let new_module = Rc::new(Module::new(
 641                 BlockParentLink(Rc::downgrade(parent), block_id),
 642                 None,
 643                 AnonymousModuleKind,
 644                 false,
 645                 false));
 646             parent.anonymous_children.borrow_mut().insert(block_id, new_module.clone());
 647             new_module
 648         } else {
 649             parent.clone()
 650         }
 651     }
 652
 653     fn handle_external_def(&mut self,
 654                            def: Def,
 655                            vis: Visibility,
 656                            child_name_bindings: &NameBindings,
 657                            final_ident: &str,
 658                            name: Name,
 659                            new_parent: &Rc<Module>) {
 660         debug!("(building reduced graph for \
 661                 external crate) building external def {}, priv {:?}",
 662                final_ident, vis);
 663         let is_public = vis == ast::Public;
 664         let modifiers = if is_public {
 665             DefModifiers::PUBLIC
 666         } else {
 667             DefModifiers::empty()
 668         } | DefModifiers::IMPORTABLE;
 669         let is_exported = is_public && match new_parent.def_id.get() {
 670             None => true,
 671             Some(did) => self.external_exports.contains(&did)
 672         };
 673         if is_exported {
 674             self.external_exports.insert(def.def_id());
 675         }
 676
 677         let kind = match def {
 678             DefTy(_, true) => EnumModuleKind,
 679             DefTy(_, false) | DefStruct(..) => TypeModuleKind,
 680             _ => NormalModuleKind
 681         };
 682
 683         match def {
 684           DefMod(def_id) | DefForeignMod(def_id) | DefStruct(def_id) |
 685           DefTy(def_id, _) => {
 686             let type_def = child_name_bindings.type_def.borrow().clone();
 687             match type_def {
 688               Some(TypeNsDef { module_def: Some(module_def), .. }) => {
 689                 debug!("(building reduced graph for external crate) \
 690                         already created module");
 691                 module_def.def_id.set(Some(def_id));
 692               }
 693               Some(_) | None => {
 694                 debug!("(building reduced graph for \
 695                         external crate) building module \
 696                         {} {}", final_ident, is_public);
 697                 let parent_link = self.get_parent_link(new_parent, name);
 698
 699                 child_name_bindings.define_module(parent_link,
 700                                                   Some(def_id),
 701                                                   kind,
 702                                                   true,
 703                                                   is_public,
 704                                                   DUMMY_SP);
 705               }
 706             }
 707           }
 708           _ => {}
 709         }
 710
 711         match def {
 712           DefMod(_) | DefForeignMod(_) => {}
 713           DefVariant(_, variant_id, is_struct) => {
 714               debug!("(building reduced graph for external crate) building \
 715                       variant {}",
 716                       final_ident);
 717               // variants are always treated as importable to allow them to be
 718               // glob used
 719               let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 720               if is_struct {
 721                   child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 722                   // Not adding fields for variants as they are not accessed with a self receiver
 723                   self.structs.insert(variant_id, Vec::new());
 724               } else {
 725                   child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 726               }
 727           }
 728           DefFn(ctor_id, true) => {
 729             child_name_bindings.define_value(
 730                 csearch::get_tuple_struct_definition_if_ctor(&self.session.cstore, ctor_id)
 731                     .map_or(def, |_| DefStruct(ctor_id)), DUMMY_SP, modifiers);
 732           }
 733           DefFn(..) | DefStatic(..) | DefConst(..) | DefAssociatedConst(..) |
 734           DefMethod(..) => {
 735             debug!("(building reduced graph for external \
 736                     crate) building value (fn/static) {}", final_ident);
 737             // impl methods have already been defined with the correct importability modifier
 738             let mut modifiers = match *child_name_bindings.value_def.borrow() {
 739                 Some(ref def) => (modifiers & !DefModifiers::IMPORTABLE) |
 740                              (def.modifiers &  DefModifiers::IMPORTABLE),
 741                 None => modifiers
 742             };
 743             if new_parent.kind.get() != NormalModuleKind {
 744                 modifiers = modifiers & !DefModifiers::IMPORTABLE;
 745             }
 746             child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 747           }
 748           DefTrait(def_id) => {
 749               debug!("(building reduced graph for external \
 750                       crate) building type {}", final_ident);
 751
 752               // If this is a trait, add all the trait item names to the trait
 753               // info.
 754
 755               let trait_item_def_ids =
 756                 csearch::get_trait_item_def_ids(&self.session.cstore, def_id);
 757               for trait_item_def in &trait_item_def_ids {
 758                   let trait_item_name = csearch::get_trait_name(&self.session.cstore,
 759                                                                 trait_item_def.def_id());
 760
 761                   debug!("(building reduced graph for external crate) ... \
 762                           adding trait item '{}'",
 763                          trait_item_name);
 764
 765                   self.trait_item_map.insert((trait_item_name, def_id),
 766                                              trait_item_def.def_id());
 767
 768                   if is_exported {
 769                       self.external_exports.insert(trait_item_def.def_id());
 770                   }
 771               }
 772
 773               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 774
 775               // Define a module if necessary.
 776               let parent_link = self.get_parent_link(new_parent, name);
 777               child_name_bindings.set_module_kind(parent_link,
 778                                                   Some(def_id),
 779                                                   TraitModuleKind,
 780                                                   true,
 781                                                   is_public,
 782                                                   DUMMY_SP)
 783           }
 784           DefTy(..) | DefAssociatedTy(..) => {
 785               debug!("(building reduced graph for external \
 786                       crate) building type {}", final_ident);
 787
 788               let modifiers = match new_parent.kind.get() {
 789                   NormalModuleKind => modifiers,
 790                   _ => modifiers & !DefModifiers::IMPORTABLE
 791               };
 792
 793               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 794           }
 795           DefStruct(def_id) => {
 796             debug!("(building reduced graph for external \
 797                     crate) building type and value for {}",
 798                    final_ident);
 799             child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 800             let fields = csearch::get_struct_field_names(&self.session.cstore, def_id);
 801
 802             if fields.is_empty() {
 803                 child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 804             }
 805
 806             // Record the def ID and fields of this struct.
 807             self.structs.insert(def_id, fields);
 808           }
 809           DefLocal(..) | DefPrimTy(..) | DefTyParam(..) |
 810           DefUse(..) | DefUpvar(..) | DefRegion(..) |
 811           DefLabel(..) | DefSelfTy(..) => {
 812             panic!("didn't expect `{:?}`", def);
 813           }
 814         }
 815     }
 816
 817     /// Builds the reduced graph for a single item in an external crate.
 818     fn build_reduced_graph_for_external_crate_def(&mut self,
 819                                                   root: &Rc<Module>,
 820                                                   def_like: DefLike,
 821                                                   name: Name,
 822                                                   def_visibility: Visibility) {
 823         match def_like {
 824             DlDef(def) => {
 825                 // Add the new child item, if necessary.
 826                 match def {
 827                     DefForeignMod(def_id) => {
 828                         // Foreign modules have no names. Recur and populate
 829                         // eagerly.
 830                         csearch::each_child_of_item(&self.session.cstore,
 831                                                     def_id,
 832                                                     |def_like,
 833                                                      child_name,
 834                                                      vis| {
 835                             self.build_reduced_graph_for_external_crate_def(
 836                                 root,
 837                                 def_like,
 838                                 child_name,
 839                                 vis)
 840                         });
 841                     }
 842                     _ => {
 843                         let child_name_bindings =
 844                             self.add_child(name,
 845                                            root,
 846                                            OverwriteDuplicates,
 847                                            DUMMY_SP);
 848
 849                         self.handle_external_def(def,
 850                                                  def_visibility,
 851                                                  &*child_name_bindings,
 852                                                  &name.as_str(),
 853                                                  name,
 854                                                  root);
 855                     }
 856                 }
 857             }
 858             DlImpl(_) => {
 859                 debug!("(building reduced graph for external crate) \
 860                         ignoring impl");
 861             }
 862             DlField => {
 863                 debug!("(building reduced graph for external crate) \
 864                         ignoring field");
 865             }
 866         }
 867     }
 868
 869     /// Builds the reduced graph rooted at the given external module.
 870     fn populate_external_module(&mut self, module: &Rc<Module>) {
 871         debug!("(populating external module) attempting to populate {}",
 872                module_to_string(&**module));
 873
 874         let def_id = match module.def_id.get() {
 875             None => {
 876                 debug!("(populating external module) ... no def ID!");
 877                 return
 878             }
 879             Some(def_id) => def_id,
 880         };
 881
 882         csearch::each_child_of_item(&self.session.cstore,
 883                                     def_id,
 884                                     |def_like, child_name, visibility| {
 885             debug!("(populating external module) ... found ident: {}",
 886                    child_name);
 887             self.build_reduced_graph_for_external_crate_def(module,
 888                                                             def_like,
 889                                                             child_name,
 890                                                             visibility)
 891         });
 892         module.populated.set(true)
 893     }
 894
 895     /// Ensures that the reduced graph rooted at the given external module
 896     /// is built, building it if it is not.
 897     fn populate_module_if_necessary(&mut self, module: &Rc<Module>) {
 898         if !module.populated.get() {
 899             self.populate_external_module(module)
 900         }
 901         assert!(module.populated.get())
 902     }
 903
 904     /// Builds the reduced graph rooted at the 'use' directive for an external
 905     /// crate.
 906     fn build_reduced_graph_for_external_crate(&mut self, root: &Rc<Module>) {
 907         csearch::each_top_level_item_of_crate(&self.session.cstore,
 908                                               root.def_id
 909                                                   .get()
 910                                                   .unwrap()
 911                                                   .krate,
 912                                               |def_like, name, visibility| {
 913             self.build_reduced_graph_for_external_crate_def(root, def_like, name, visibility)
 914         });
 915     }
 916
 917     /// Creates and adds an import directive to the given module.
 918     fn build_import_directive(&mut self,
 919                               module_: &Module,
 920                               module_path: Vec<Name>,
 921                               subclass: ImportDirectiveSubclass,
 922                               span: Span,
 923                               id: NodeId,
 924                               is_public: bool,
 925                               shadowable: Shadowable) {
 926         module_.imports.borrow_mut().push(ImportDirective::new(module_path,
 927                                                                subclass,
 928                                                                span,
 929                                                                id,
 930                                                                is_public,
 931                                                                shadowable));
 932         self.unresolved_imports += 1;
 933
 934         if is_public {
 935             module_.inc_pub_count();
 936         }
 937
 938         // Bump the reference count on the name. Or, if this is a glob, set
 939         // the appropriate flag.
 940
 941         match subclass {
 942             SingleImport(target, _) => {
 943                 debug!("(building import directive) building import directive: {}::{}",
 944                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 945                        target);
 946
 947                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 948                 match import_resolutions.get_mut(&target) {
 949                     Some(resolution) => {
 950                         debug!("(building import directive) bumping reference");
 951                         resolution.outstanding_references += 1;
 952
 953                         // the source of this name is different now
 954                         resolution.type_id = id;
 955                         resolution.value_id = id;
 956                         resolution.is_public = is_public;
 957                         return;
 958                     }
 959                     None => {}
 960                 }
 961                 debug!("(building import directive) creating new");
 962                 let mut resolution = ImportResolution::new(id, is_public);
 963                 resolution.outstanding_references = 1;
 964                 import_resolutions.insert(target, resolution);
 965             }
 966             GlobImport => {
 967                 // Set the glob flag. This tells us that we don't know the
 968                 // module's exports ahead of time.
 969
 970                 module_.inc_glob_count();
 971                 if is_public {
 972                     module_.inc_pub_glob_count();
 973                 }
 974             }
 975         }
 976     }
 977 }
 978
 979 struct BuildReducedGraphVisitor<'a, 'b:'a, 'tcx:'b> {
 980     builder: GraphBuilder<'a, 'b, 'tcx>,
 981     parent: Rc<Module>
 982 }
 983
 984 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 985     fn visit_item(&mut self, item: &Item) {
 986         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 987         let old_parent = replace(&mut self.parent, p);
 988         visit::walk_item(self, item);
 989         self.parent = old_parent;
 990     }
 991
 992     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 993         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 994     }
 995
 996     fn visit_block(&mut self, block: &Block) {
 997         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 998         let old_parent = replace(&mut self.parent, np);
 999         visit::walk_block(self, block);
1000         self.parent = old_parent;
1001     }
1002 }
1003
1004 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &ast::Crate) {
1005     GraphBuilder {
1006         resolver: resolver
1007     }.build_reduced_graph(krate);
1008 }
1009
1010 pub fn populate_module_if_necessary(resolver: &mut Resolver, module: &Rc<Module>) {
1011     GraphBuilder {
1012         resolver: resolver
1013     }.populate_module_if_necessary(module);
1014 }