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