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                     self.resolve_error(sp,
 212                         &format!("duplicate definition of {} `{}`",
 213                              namespace_error_to_string(duplicate_type),
 214                              token::get_name(name)));
 215                     {
 216                         let r = child.span_for_namespace(ns);
 217                         if let Some(sp) = r {
 218                             self.session.span_note(sp,
 219                                  &format!("first definition of {} `{}` here",
 220                                       namespace_error_to_string(duplicate_type),
 221                                       token::get_name(name)));
 222                         }
 223                     }
 224                 }
 225                 child
 226             }
 227         }
 228     }
 229
 230     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 231         // Check each statement.
 232         for statement in &block.stmts {
 233             match statement.node {
 234                 StmtDecl(ref declaration, _) => {
 235                     match declaration.node {
 236                         DeclItem(_) => {
 237                             return true;
 238                         }
 239                         _ => {
 240                             // Keep searching.
 241                         }
 242                     }
 243                 }
 244                 _ => {
 245                     // Keep searching.
 246                 }
 247             }
 248         }
 249
 250         // If we found no items, we don't need to create
 251         // an anonymous module.
 252
 253         return false;
 254     }
 255
 256     fn get_parent_link(&mut self, parent: &Rc<Module>, name: Name) -> ParentLink {
 257         ModuleParentLink(parent.downgrade(), name)
 258     }
 259
 260     /// Constructs the reduced graph for one item.
 261     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: &Rc<Module>) -> Rc<Module> {
 262         let name = item.ident.name;
 263         let sp = item.span;
 264         let is_public = item.vis == ast::Public;
 265         let modifiers = if is_public {
 266             DefModifiers::PUBLIC
 267         } else {
 268             DefModifiers::empty()
 269         } | DefModifiers::IMPORTABLE;
 270
 271         match item.node {
 272             ItemUse(ref view_path) => {
 273                 // Extract and intern the module part of the path. For
 274                 // globs and lists, the path is found directly in the AST;
 275                 // for simple paths we have to munge the path a little.
 276                 let module_path = match view_path.node {
 277                     ViewPathSimple(_, ref full_path) => {
 278                         full_path.segments
 279                             .init()
 280                             .iter().map(|ident| ident.identifier.name)
 281                             .collect()
 282                     }
 283
 284                     ViewPathGlob(ref module_ident_path) |
 285                     ViewPathList(ref module_ident_path, _) => {
 286                         module_ident_path.segments
 287                             .iter().map(|ident| ident.identifier.name).collect()
 288                     }
 289                 };
 290
 291                 // Build up the import directives.
 292                 let shadowable = item.attrs.iter().any(|attr| {
 293                     attr.name() == token::get_name(special_idents::prelude_import.name)
 294                 });
 295                 let shadowable = if shadowable {
 296                     Shadowable::Always
 297                 } else {
 298                     Shadowable::Never
 299                 };
 300
 301                 match view_path.node {
 302                     ViewPathSimple(binding, ref full_path) => {
 303                         let source_name =
 304                             full_path.segments.last().unwrap().identifier.name;
 305                         if &token::get_name(source_name)[..] == "mod" ||
 306                            &token::get_name(source_name)[..] == "self" {
 307                             self.resolve_error(view_path.span,
 308                                 "`self` imports are only allowed within a { } list");
 309                         }
 310
 311                         let subclass = SingleImport(binding.name,
 312                                                     source_name);
 313                         self.build_import_directive(&**parent,
 314                                                     module_path,
 315                                                     subclass,
 316                                                     view_path.span,
 317                                                     item.id,
 318                                                     is_public,
 319                                                     shadowable);
 320                     }
 321                     ViewPathList(_, ref source_items) => {
 322                         // Make sure there's at most one `mod` import in the list.
 323                         let mod_spans = source_items.iter().filter_map(|item| match item.node {
 324                             PathListMod { .. } => Some(item.span),
 325                             _ => None
 326                         }).collect::<Vec<Span>>();
 327                         if mod_spans.len() > 1 {
 328                             self.resolve_error(mod_spans[0],
 329                                 "`self` import can only appear once in the list");
 330                             for other_span in mod_spans.iter().skip(1) {
 331                                 self.session.span_note(*other_span,
 332                                     "another `self` import appears here");
 333                             }
 334                         }
 335
 336                         for source_item in source_items {
 337                             let (module_path, name) = match source_item.node {
 338                                 PathListIdent { name, .. } =>
 339                                     (module_path.clone(), name.name),
 340                                 PathListMod { .. } => {
 341                                     let name = match module_path.last() {
 342                                         Some(name) => *name,
 343                                         None => {
 344                                             self.resolve_error(source_item.span,
 345                                                 "`self` import can only appear in an import list \
 346                                                  with a non-empty prefix");
 347                                             continue;
 348                                         }
 349                                     };
 350                                     let module_path = module_path.init();
 351                                     (module_path.to_vec(), name)
 352                                 }
 353                             };
 354                             self.build_import_directive(
 355                                 &**parent,
 356                                 module_path,
 357                                 SingleImport(name, name),
 358                                 source_item.span,
 359                                 source_item.node.id(),
 360                                 is_public,
 361                                 shadowable);
 362                         }
 363                     }
 364                     ViewPathGlob(_) => {
 365                         self.build_import_directive(&**parent,
 366                                                     module_path,
 367                                                     GlobImport,
 368                                                     view_path.span,
 369                                                     item.id,
 370                                                     is_public,
 371                                                     shadowable);
 372                     }
 373                 }
 374                 parent.clone()
 375             }
 376
 377             ItemExternCrate(_) => {
 378                 // n.b. we don't need to look at the path option here, because cstore already did
 379                 if let Some(crate_id) = self.session.cstore.find_extern_mod_stmt_cnum(item.id) {
 380                     let def_id = DefId { krate: crate_id, node: 0 };
 381                     self.external_exports.insert(def_id);
 382                     let parent_link = ModuleParentLink(parent.downgrade(), name);
 383                     let external_module = Rc::new(Module::new(parent_link,
 384                                                               Some(def_id),
 385                                                               NormalModuleKind,
 386                                                               false,
 387                                                               true));
 388                     debug!("(build reduced graph for item) found extern `{}`",
 389                             module_to_string(&*external_module));
 390                     self.check_for_conflicts_between_external_crates(&**parent, name, sp);
 391                     parent.external_module_children.borrow_mut()
 392                           .insert(name, external_module.clone());
 393                     self.build_reduced_graph_for_external_crate(&external_module);
 394                 }
 395                 parent.clone()
 396             }
 397
 398             ItemMod(..) => {
 399                 let name_bindings = self.add_child(name, parent, ForbidDuplicateModules, sp);
 400
 401                 let parent_link = self.get_parent_link(parent, name);
 402                 let def_id = DefId { krate: 0, node: item.id };
 403                 name_bindings.define_module(parent_link,
 404                                             Some(def_id),
 405                                             NormalModuleKind,
 406                                             false,
 407                                             is_public,
 408                                             sp);
 409
 410                 name_bindings.get_module()
 411             }
 412
 413             ItemForeignMod(..) => parent.clone(),
 414
 415             // These items live in the value namespace.
 416             ItemStatic(_, m, _) => {
 417                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 418                 let mutbl = m == ast::MutMutable;
 419
 420                 name_bindings.define_value(DefStatic(local_def(item.id), mutbl), sp, modifiers);
 421                 parent.clone()
 422             }
 423             ItemConst(_, _) => {
 424                 self.add_child(name, parent, ForbidDuplicateValues, sp)
 425                     .define_value(DefConst(local_def(item.id)), sp, modifiers);
 426                 parent.clone()
 427             }
 428             ItemFn(_, _, _, _, _, _) => {
 429                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 430
 431                 let def = DefFn(local_def(item.id), false);
 432                 name_bindings.define_value(def, sp, modifiers);
 433                 parent.clone()
 434             }
 435
 436             // These items live in the type namespace.
 437             ItemTy(..) => {
 438                 let name_bindings =
 439                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 440
 441                 name_bindings.define_type(DefTy(local_def(item.id), false), sp,
 442                                           modifiers);
 443
 444                 let parent_link = self.get_parent_link(parent, name);
 445                 name_bindings.set_module_kind(parent_link,
 446                                               Some(local_def(item.id)),
 447                                               TypeModuleKind,
 448                                               false,
 449                                               is_public,
 450                                               sp);
 451                 parent.clone()
 452             }
 453
 454             ItemEnum(ref enum_definition, _) => {
 455                 let name_bindings =
 456                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 457
 458                 name_bindings.define_type(DefTy(local_def(item.id), true), sp, modifiers);
 459
 460                 let parent_link = self.get_parent_link(parent, name);
 461                 name_bindings.set_module_kind(parent_link,
 462                                               Some(local_def(item.id)),
 463                                               EnumModuleKind,
 464                                               false,
 465                                               is_public,
 466                                               sp);
 467
 468                 let module = name_bindings.get_module();
 469
 470                 for variant in &(*enum_definition).variants {
 471                     self.build_reduced_graph_for_variant(
 472                         &**variant,
 473                         local_def(item.id),
 474                         &module);
 475                 }
 476                 parent.clone()
 477             }
 478
 479             // These items live in both the type and value namespaces.
 480             ItemStruct(ref struct_def, _) => {
 481                 // Adding to both Type and Value namespaces or just Type?
 482                 let (forbid, ctor_id) = match struct_def.ctor_id {
 483                     Some(ctor_id)   => (ForbidDuplicateTypesAndValues, Some(ctor_id)),
 484                     None            => (ForbidDuplicateTypesAndModules, None)
 485                 };
 486
 487                 let name_bindings = self.add_child(name, parent, forbid, sp);
 488
 489                 // Define a name in the type namespace.
 490                 name_bindings.define_type(DefTy(local_def(item.id), false), sp, modifiers);
 491
 492                 // If this is a newtype or unit-like struct, define a name
 493                 // in the value namespace as well
 494                 if let Some(cid) = ctor_id {
 495                     name_bindings.define_value(DefStruct(local_def(cid)), sp, modifiers);
 496                 }
 497
 498                 // Record the def ID and fields of this struct.
 499                 let named_fields = struct_def.fields.iter().filter_map(|f| {
 500                     match f.node.kind {
 501                         NamedField(ident, _) => Some(ident.name),
 502                         UnnamedField(_) => None
 503                     }
 504                 }).collect();
 505                 self.structs.insert(local_def(item.id), named_fields);
 506
 507                 parent.clone()
 508             }
 509
 510             ItemDefaultImpl(_, _) |
 511             ItemImpl(..) => parent.clone(),
 512
 513             ItemTrait(_, _, _, ref items) => {
 514                 let name_bindings =
 515                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 516
 517                 // Add all the items within to a new module.
 518                 let parent_link = self.get_parent_link(parent, name);
 519                 name_bindings.define_module(parent_link,
 520                                             Some(local_def(item.id)),
 521                                             TraitModuleKind,
 522                                             false,
 523                                             is_public,
 524                                             sp);
 525                 let module_parent = name_bindings.get_module();
 526
 527                 let def_id = local_def(item.id);
 528
 529                 // Add the names of all the items to the trait info.
 530                 for trait_item in items {
 531                     let name_bindings = self.add_child(trait_item.ident.name,
 532                                         &module_parent,
 533                                         ForbidDuplicateTypesAndValues,
 534                                         trait_item.span);
 535
 536                     match trait_item.node {
 537                         ast::ConstTraitItem(..) => {
 538                             let def = DefAssociatedConst(local_def(trait_item.id),
 539                                                          FromTrait(local_def(item.id)));
 540                             // NB: not DefModifiers::IMPORTABLE
 541                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 542                         }
 543                         ast::MethodTraitItem(..) => {
 544                             let def = DefMethod(local_def(trait_item.id),
 545                                                 FromTrait(local_def(item.id)));
 546                             // NB: not DefModifiers::IMPORTABLE
 547                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 548                         }
 549                         ast::TypeTraitItem(..) => {
 550                             let def = DefAssociatedTy(local_def(item.id),
 551                                                       local_def(trait_item.id));
 552                             // NB: not DefModifiers::IMPORTABLE
 553                             name_bindings.define_type(def, trait_item.span, DefModifiers::PUBLIC);
 554                         }
 555                     }
 556
 557                     self.trait_item_map.insert((trait_item.ident.name, def_id),
 558                                                local_def(trait_item.id));
 559                 }
 560
 561                 name_bindings.define_type(DefTrait(def_id), sp, modifiers);
 562                 parent.clone()
 563             }
 564             ItemMac(..) => parent.clone()
 565         }
 566     }
 567
 568     // Constructs the reduced graph for one variant. Variants exist in the
 569     // type and value namespaces.
 570     fn build_reduced_graph_for_variant(&mut self,
 571                                        variant: &Variant,
 572                                        item_id: DefId,
 573                                        parent: &Rc<Module>) {
 574         let name = variant.node.name.name;
 575         let is_exported = match variant.node.kind {
 576             TupleVariantKind(_) => false,
 577             StructVariantKind(_) => {
 578                 // Not adding fields for variants as they are not accessed with a self receiver
 579                 self.structs.insert(local_def(variant.node.id), Vec::new());
 580                 true
 581             }
 582         };
 583
 584         let child = self.add_child(name, parent,
 585                                    ForbidDuplicateTypesAndValues,
 586                                    variant.span);
 587         // variants are always treated as importable to allow them to be glob
 588         // used
 589         child.define_value(DefVariant(item_id,
 590                                       local_def(variant.node.id), is_exported),
 591                            variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 592         child.define_type(DefVariant(item_id,
 593                                      local_def(variant.node.id), is_exported),
 594                           variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 595     }
 596
 597     /// Constructs the reduced graph for one foreign item.
 598     fn build_reduced_graph_for_foreign_item(&mut self,
 599                                             foreign_item: &ForeignItem,
 600                                             parent: &Rc<Module>) {
 601         let name = foreign_item.ident.name;
 602         let is_public = foreign_item.vis == ast::Public;
 603         let modifiers = if is_public {
 604             DefModifiers::PUBLIC
 605         } else {
 606             DefModifiers::empty()
 607         } | DefModifiers::IMPORTABLE;
 608         let name_bindings =
 609             self.add_child(name, parent, ForbidDuplicateValues,
 610                            foreign_item.span);
 611
 612         let def = match foreign_item.node {
 613             ForeignItemFn(..) => {
 614                 DefFn(local_def(foreign_item.id), false)
 615             }
 616             ForeignItemStatic(_, m) => {
 617                 DefStatic(local_def(foreign_item.id), m)
 618             }
 619         };
 620         name_bindings.define_value(def, foreign_item.span, modifiers);
 621     }
 622
 623     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &Rc<Module>) -> Rc<Module> {
 624         if self.block_needs_anonymous_module(block) {
 625             let block_id = block.id;
 626
 627             debug!("(building reduced graph for block) creating a new \
 628                     anonymous module for block {}",
 629                    block_id);
 630
 631             let new_module = Rc::new(Module::new(
 632                 BlockParentLink(parent.downgrade(), block_id),
 633                 None,
 634                 AnonymousModuleKind,
 635                 false,
 636                 false));
 637             parent.anonymous_children.borrow_mut().insert(block_id, new_module.clone());
 638             new_module
 639         } else {
 640             parent.clone()
 641         }
 642     }
 643
 644     fn handle_external_def(&mut self,
 645                            def: Def,
 646                            vis: Visibility,
 647                            child_name_bindings: &NameBindings,
 648                            final_ident: &str,
 649                            name: Name,
 650                            new_parent: &Rc<Module>) {
 651         debug!("(building reduced graph for \
 652                 external crate) building external def {}, priv {:?}",
 653                final_ident, vis);
 654         let is_public = vis == ast::Public;
 655         let modifiers = if is_public {
 656             DefModifiers::PUBLIC
 657         } else {
 658             DefModifiers::empty()
 659         } | DefModifiers::IMPORTABLE;
 660         let is_exported = is_public && match new_parent.def_id.get() {
 661             None => true,
 662             Some(did) => self.external_exports.contains(&did)
 663         };
 664         if is_exported {
 665             self.external_exports.insert(def.def_id());
 666         }
 667
 668         let kind = match def {
 669             DefTy(_, true) => EnumModuleKind,
 670             DefTy(_, false) | DefStruct(..) => TypeModuleKind,
 671             _ => NormalModuleKind
 672         };
 673
 674         match def {
 675           DefMod(def_id) | DefForeignMod(def_id) | DefStruct(def_id) |
 676           DefTy(def_id, _) => {
 677             let type_def = child_name_bindings.type_def.borrow().clone();
 678             match type_def {
 679               Some(TypeNsDef { module_def: Some(module_def), .. }) => {
 680                 debug!("(building reduced graph for external crate) \
 681                         already created module");
 682                 module_def.def_id.set(Some(def_id));
 683               }
 684               Some(_) | None => {
 685                 debug!("(building reduced graph for \
 686                         external crate) building module \
 687                         {} {}", final_ident, is_public);
 688                 let parent_link = self.get_parent_link(new_parent, name);
 689
 690                 child_name_bindings.define_module(parent_link,
 691                                                   Some(def_id),
 692                                                   kind,
 693                                                   true,
 694                                                   is_public,
 695                                                   DUMMY_SP);
 696               }
 697             }
 698           }
 699           _ => {}
 700         }
 701
 702         match def {
 703           DefMod(_) | DefForeignMod(_) => {}
 704           DefVariant(_, variant_id, is_struct) => {
 705               debug!("(building reduced graph for external crate) building \
 706                       variant {}",
 707                       final_ident);
 708               // variants are always treated as importable to allow them to be
 709               // glob used
 710               let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 711               if is_struct {
 712                   child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 713                   // Not adding fields for variants as they are not accessed with a self receiver
 714                   self.structs.insert(variant_id, Vec::new());
 715               } else {
 716                   child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 717               }
 718           }
 719           DefFn(ctor_id, true) => {
 720             child_name_bindings.define_value(
 721                 csearch::get_tuple_struct_definition_if_ctor(&self.session.cstore, ctor_id)
 722                     .map_or(def, |_| DefStruct(ctor_id)), DUMMY_SP, modifiers);
 723           }
 724           DefFn(..) | DefStatic(..) | DefConst(..) | DefAssociatedConst(..) |
 725           DefMethod(..) => {
 726             debug!("(building reduced graph for external \
 727                     crate) building value (fn/static) {}", final_ident);
 728             // impl methods have already been defined with the correct importability modifier
 729             let mut modifiers = match *child_name_bindings.value_def.borrow() {
 730                 Some(ref def) => (modifiers & !DefModifiers::IMPORTABLE) |
 731                              (def.modifiers &  DefModifiers::IMPORTABLE),
 732                 None => modifiers
 733             };
 734             if new_parent.kind.get() != NormalModuleKind {
 735                 modifiers = modifiers & !DefModifiers::IMPORTABLE;
 736             }
 737             child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 738           }
 739           DefTrait(def_id) => {
 740               debug!("(building reduced graph for external \
 741                       crate) building type {}", final_ident);
 742
 743               // If this is a trait, add all the trait item names to the trait
 744               // info.
 745
 746               let trait_item_def_ids =
 747                 csearch::get_trait_item_def_ids(&self.session.cstore, def_id);
 748               for trait_item_def in &trait_item_def_ids {
 749                   let trait_item_name = csearch::get_trait_name(&self.session.cstore,
 750                                                                 trait_item_def.def_id());
 751
 752                   debug!("(building reduced graph for external crate) ... \
 753                           adding trait item '{}'",
 754                          token::get_name(trait_item_name));
 755
 756                   self.trait_item_map.insert((trait_item_name, def_id),
 757                                              trait_item_def.def_id());
 758
 759                   if is_exported {
 760                       self.external_exports.insert(trait_item_def.def_id());
 761                   }
 762               }
 763
 764               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 765
 766               // Define a module if necessary.
 767               let parent_link = self.get_parent_link(new_parent, name);
 768               child_name_bindings.set_module_kind(parent_link,
 769                                                   Some(def_id),
 770                                                   TraitModuleKind,
 771                                                   true,
 772                                                   is_public,
 773                                                   DUMMY_SP)
 774           }
 775           DefTy(..) | DefAssociatedTy(..) => {
 776               debug!("(building reduced graph for external \
 777                       crate) building type {}", final_ident);
 778
 779               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 780           }
 781           DefStruct(def_id) => {
 782             debug!("(building reduced graph for external \
 783                     crate) building type and value for {}",
 784                    final_ident);
 785             child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 786             let fields = csearch::get_struct_fields(&self.session.cstore, def_id).iter().map(|f| {
 787                 f.name
 788             }).collect::<Vec<_>>();
 789
 790             if fields.is_empty() {
 791                 child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 792             }
 793
 794             // Record the def ID and fields of this struct.
 795             self.structs.insert(def_id, fields);
 796           }
 797           DefLocal(..) | DefPrimTy(..) | DefTyParam(..) |
 798           DefUse(..) | DefUpvar(..) | DefRegion(..) |
 799           DefLabel(..) | DefSelfTy(..) => {
 800             panic!("didn't expect `{:?}`", def);
 801           }
 802         }
 803     }
 804
 805     /// Builds the reduced graph for a single item in an external crate.
 806     fn build_reduced_graph_for_external_crate_def(&mut self,
 807                                                   root: &Rc<Module>,
 808                                                   def_like: DefLike,
 809                                                   name: Name,
 810                                                   def_visibility: Visibility) {
 811         match def_like {
 812             DlDef(def) => {
 813                 // Add the new child item, if necessary.
 814                 match def {
 815                     DefForeignMod(def_id) => {
 816                         // Foreign modules have no names. Recur and populate
 817                         // eagerly.
 818                         csearch::each_child_of_item(&self.session.cstore,
 819                                                     def_id,
 820                                                     |def_like,
 821                                                      child_name,
 822                                                      vis| {
 823                             self.build_reduced_graph_for_external_crate_def(
 824                                 root,
 825                                 def_like,
 826                                 child_name,
 827                                 vis)
 828                         });
 829                     }
 830                     _ => {
 831                         let child_name_bindings =
 832                             self.add_child(name,
 833                                            root,
 834                                            OverwriteDuplicates,
 835                                            DUMMY_SP);
 836
 837                         self.handle_external_def(def,
 838                                                  def_visibility,
 839                                                  &*child_name_bindings,
 840                                                  &token::get_name(name),
 841                                                  name,
 842                                                  root);
 843                     }
 844                 }
 845             }
 846             DlImpl(_) => {
 847                 debug!("(building reduced graph for external crate) \
 848                         ignoring impl");
 849             }
 850             DlField => {
 851                 debug!("(building reduced graph for external crate) \
 852                         ignoring field");
 853             }
 854         }
 855     }
 856
 857     /// Builds the reduced graph rooted at the given external module.
 858     fn populate_external_module(&mut self, module: &Rc<Module>) {
 859         debug!("(populating external module) attempting to populate {}",
 860                module_to_string(&**module));
 861
 862         let def_id = match module.def_id.get() {
 863             None => {
 864                 debug!("(populating external module) ... no def ID!");
 865                 return
 866             }
 867             Some(def_id) => def_id,
 868         };
 869
 870         csearch::each_child_of_item(&self.session.cstore,
 871                                     def_id,
 872                                     |def_like, child_name, visibility| {
 873             debug!("(populating external module) ... found ident: {}",
 874                    token::get_name(child_name));
 875             self.build_reduced_graph_for_external_crate_def(module,
 876                                                             def_like,
 877                                                             child_name,
 878                                                             visibility)
 879         });
 880         module.populated.set(true)
 881     }
 882
 883     /// Ensures that the reduced graph rooted at the given external module
 884     /// is built, building it if it is not.
 885     fn populate_module_if_necessary(&mut self, module: &Rc<Module>) {
 886         if !module.populated.get() {
 887             self.populate_external_module(module)
 888         }
 889         assert!(module.populated.get())
 890     }
 891
 892     /// Builds the reduced graph rooted at the 'use' directive for an external
 893     /// crate.
 894     fn build_reduced_graph_for_external_crate(&mut self, root: &Rc<Module>) {
 895         csearch::each_top_level_item_of_crate(&self.session.cstore,
 896                                               root.def_id
 897                                                   .get()
 898                                                   .unwrap()
 899                                                   .krate,
 900                                               |def_like, name, visibility| {
 901             self.build_reduced_graph_for_external_crate_def(root, def_like, name, visibility)
 902         });
 903     }
 904
 905     /// Creates and adds an import directive to the given module.
 906     fn build_import_directive(&mut self,
 907                               module_: &Module,
 908                               module_path: Vec<Name>,
 909                               subclass: ImportDirectiveSubclass,
 910                               span: Span,
 911                               id: NodeId,
 912                               is_public: bool,
 913                               shadowable: Shadowable) {
 914         module_.imports.borrow_mut().push(ImportDirective::new(module_path,
 915                                                                subclass,
 916                                                                span,
 917                                                                id,
 918                                                                is_public,
 919                                                                shadowable));
 920         self.unresolved_imports += 1;
 921         // Bump the reference count on the name. Or, if this is a glob, set
 922         // the appropriate flag.
 923
 924         match subclass {
 925             SingleImport(target, _) => {
 926                 debug!("(building import directive) building import directive: {}::{}",
 927                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 928                        token::get_name(target));
 929
 930                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 931                 match import_resolutions.get_mut(&target) {
 932                     Some(resolution) => {
 933                         debug!("(building import directive) bumping reference");
 934                         resolution.outstanding_references += 1;
 935
 936                         // the source of this name is different now
 937                         resolution.type_id = id;
 938                         resolution.value_id = id;
 939                         resolution.is_public = is_public;
 940                         return;
 941                     }
 942                     None => {}
 943                 }
 944                 debug!("(building import directive) creating new");
 945                 let mut resolution = ImportResolution::new(id, is_public);
 946                 resolution.outstanding_references = 1;
 947                 import_resolutions.insert(target, resolution);
 948             }
 949             GlobImport => {
 950                 // Set the glob flag. This tells us that we don't know the
 951                 // module's exports ahead of time.
 952
 953                 module_.glob_count.set(module_.glob_count.get() + 1);
 954             }
 955         }
 956     }
 957 }
 958
 959 struct BuildReducedGraphVisitor<'a, 'b:'a, 'tcx:'b> {
 960     builder: GraphBuilder<'a, 'b, 'tcx>,
 961     parent: Rc<Module>
 962 }
 963
 964 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 965     fn visit_item(&mut self, item: &Item) {
 966         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 967         let old_parent = replace(&mut self.parent, p);
 968         visit::walk_item(self, item);
 969         self.parent = old_parent;
 970     }
 971
 972     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 973         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 974     }
 975
 976     fn visit_block(&mut self, block: &Block) {
 977         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 978         let old_parent = replace(&mut self.parent, np);
 979         visit::walk_block(self, block);
 980         self.parent = old_parent;
 981     }
 982 }
 983
 984 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &ast::Crate) {
 985     GraphBuilder {
 986         resolver: resolver
 987     }.build_reduced_graph(krate);
 988 }
 989
 990 pub fn populate_module_if_necessary(resolver: &mut Resolver, module: &Rc<Module>) {
 991     GraphBuilder {
 992         resolver: resolver
 993     }.populate_module_if_necessary(module);
 994 }