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