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 Module;
  20 use Namespace::{self, TypeNS, ValueNS};
  21 use {NameBinding, NameBindingKind};
  22 use module_to_string;
  23 use ParentLink::{ModuleParentLink, BlockParentLink};
  24 use Resolver;
  25 use resolve_imports::Shadowable;
  26 use {resolve_error, resolve_struct_error, ResolutionError};
  27
  28 use rustc::middle::cstore::{CrateStore, ChildItem, DlDef, DlField, DlImpl};
  29 use rustc::middle::def::*;
  30 use rustc::middle::def_id::{CRATE_DEF_INDEX, DefId};
  31 use rustc::middle::ty::VariantKind;
  32
  33 use syntax::ast::{Name, NodeId};
  34 use syntax::attr::AttrMetaMethods;
  35 use syntax::parse::token::special_idents;
  36 use syntax::codemap::{Span, DUMMY_SP};
  37
  38 use rustc_front::hir;
  39 use rustc_front::hir::{Block, DeclItem};
  40 use rustc_front::hir::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  41 use rustc_front::hir::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  42 use rustc_front::hir::{ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  43 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  44 use rustc_front::hir::{NamedField, PathListIdent, PathListMod};
  45 use rustc_front::hir::StmtDecl;
  46 use rustc_front::hir::UnnamedField;
  47 use rustc_front::hir::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  48 use rustc_front::hir::Visibility;
  49 use rustc_front::intravisit::{self, Visitor};
  50
  51 use std::mem::replace;
  52 use std::ops::{Deref, DerefMut};
  53
  54 struct GraphBuilder<'a, 'b: 'a, 'tcx: 'b> {
  55     resolver: &'a mut Resolver<'b, 'tcx>,
  56 }
  57
  58 impl<'a, 'b:'a, 'tcx:'b> Deref for GraphBuilder<'a, 'b, 'tcx> {
  59     type Target = Resolver<'b, 'tcx>;
  60
  61     fn deref(&self) -> &Resolver<'b, 'tcx> {
  62         &*self.resolver
  63     }
  64 }
  65
  66 impl<'a, 'b:'a, 'tcx:'b> DerefMut for GraphBuilder<'a, 'b, 'tcx> {
  67     fn deref_mut(&mut self) -> &mut Resolver<'b, 'tcx> {
  68         &mut *self.resolver
  69     }
  70 }
  71
  72 trait ToNameBinding<'a> {
  73     fn to_name_binding(self) -> NameBinding<'a>;
  74 }
  75
  76 impl<'a> ToNameBinding<'a> for (Module<'a>, Span) {
  77     fn to_name_binding(self) -> NameBinding<'a> {
  78         NameBinding::create_from_module(self.0, Some(self.1))
  79     }
  80 }
  81
  82 impl<'a> ToNameBinding<'a> for (Def, Span, DefModifiers) {
  83     fn to_name_binding(self) -> NameBinding<'a> {
  84         let kind = NameBindingKind::Def(self.0);
  85         NameBinding { modifiers: self.2, kind: kind, span: Some(self.1) }
  86     }
  87 }
  88
  89 impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
  90     /// Constructs the reduced graph for the entire crate.
  91     fn build_reduced_graph(self, krate: &hir::Crate) {
  92         let mut visitor = BuildReducedGraphVisitor {
  93             parent: self.graph_root,
  94             builder: self,
  95         };
  96         intravisit::walk_crate(&mut visitor, krate);
  97     }
  98
  99     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined.
 100     fn try_define<T>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T)
 101         where T: ToNameBinding<'b>
 102     {
 103         let _ = parent.try_define_child(name, ns, self.new_name_binding(def.to_name_binding()));
 104     }
 105
 106     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
 107     /// otherwise, reports an error.
 108     fn define<T: ToNameBinding<'b>>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T) {
 109         let binding = self.new_name_binding(def.to_name_binding());
 110         let old_binding = match parent.try_define_child(name, ns, binding) {
 111             Ok(()) => return,
 112             Err(old_binding) => old_binding,
 113         };
 114
 115         let span = binding.span.unwrap_or(DUMMY_SP);
 116         if !old_binding.is_extern_crate() && !binding.is_extern_crate() {
 117             // Record an error here by looking up the namespace that had the duplicate
 118             let ns_str = match ns { TypeNS => "type or module", ValueNS => "value" };
 119             let resolution_error = ResolutionError::DuplicateDefinition(ns_str, name);
 120             let mut err = resolve_struct_error(self, span, resolution_error);
 121
 122             if let Some(sp) = old_binding.span {
 123                 let note = format!("first definition of {} `{}` here", ns_str, name);
 124                 err.span_note(sp, &note);
 125             }
 126             err.emit();
 127         } else if old_binding.is_extern_crate() && binding.is_extern_crate() {
 128             span_err!(self.session,
 129                       span,
 130                       E0259,
 131                       "an external crate named `{}` has already been imported into this module",
 132                       name);
 133         } else {
 134             span_err!(self.session,
 135                       span,
 136                       E0260,
 137                       "the name `{}` conflicts with an external crate \
 138                       that has been imported into this module",
 139                       name);
 140         }
 141     }
 142
 143     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 144         fn is_item(statement: &hir::Stmt) -> bool {
 145             if let StmtDecl(ref declaration, _) = statement.node {
 146                 if let DeclItem(_) = declaration.node {
 147                     return true;
 148                 }
 149             }
 150             false
 151         }
 152
 153         // If any statements are items, we need to create an anonymous module
 154         block.stmts.iter().any(is_item)
 155     }
 156
 157     /// Constructs the reduced graph for one item.
 158     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: Module<'b>) -> Module<'b> {
 159         let name = item.name;
 160         let sp = item.span;
 161         let is_public = item.vis == hir::Public;
 162         let modifiers = if is_public {
 163             DefModifiers::PUBLIC
 164         } else {
 165             DefModifiers::empty()
 166         } | DefModifiers::IMPORTABLE;
 167
 168         match item.node {
 169             ItemUse(ref view_path) => {
 170                 // Extract and intern the module part of the path. For
 171                 // globs and lists, the path is found directly in the AST;
 172                 // for simple paths we have to munge the path a little.
 173                 let module_path = match view_path.node {
 174                     ViewPathSimple(_, ref full_path) => {
 175                         full_path.segments
 176                                  .split_last()
 177                                  .unwrap()
 178                                  .1
 179                                  .iter()
 180                                  .map(|seg| seg.identifier.name)
 181                                  .collect()
 182                     }
 183
 184                     ViewPathGlob(ref module_ident_path) |
 185                     ViewPathList(ref module_ident_path, _) => {
 186                         module_ident_path.segments
 187                                          .iter()
 188                                          .map(|seg| seg.identifier.name)
 189                                          .collect()
 190                     }
 191                 };
 192
 193                 // Build up the import directives.
 194                 let shadowable = item.attrs.iter().any(|attr| {
 195                     attr.name() == special_idents::prelude_import.name.as_str()
 196                 });
 197                 let shadowable = if shadowable {
 198                     Shadowable::Always
 199                 } else {
 200                     Shadowable::Never
 201                 };
 202
 203                 match view_path.node {
 204                     ViewPathSimple(binding, ref full_path) => {
 205                         let source_name = full_path.segments.last().unwrap().identifier.name;
 206                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 207                             resolve_error(self,
 208                                           view_path.span,
 209                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 210                         }
 211
 212                         let subclass = SingleImport(binding, source_name);
 213                         self.build_import_directive(parent,
 214                                                     module_path,
 215                                                     subclass,
 216                                                     view_path.span,
 217                                                     item.id,
 218                                                     is_public,
 219                                                     shadowable);
 220                     }
 221                     ViewPathList(_, ref source_items) => {
 222                         // Make sure there's at most one `mod` import in the list.
 223                         let mod_spans = source_items.iter()
 224                                                     .filter_map(|item| {
 225                                                         match item.node {
 226                                                             PathListMod { .. } => Some(item.span),
 227                                                             _ => None,
 228                                                         }
 229                                                     })
 230                                                     .collect::<Vec<Span>>();
 231                         if mod_spans.len() > 1 {
 232                             let mut e = resolve_struct_error(self,
 233                                           mod_spans[0],
 234                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 235                             for other_span in mod_spans.iter().skip(1) {
 236                                 e.span_note(*other_span, "another `self` import appears here");
 237                             }
 238                             e.emit();
 239                         }
 240
 241                         for source_item in source_items {
 242                             let (module_path, name, rename) = match source_item.node {
 243                                 PathListIdent { name, rename, .. } =>
 244                                     (module_path.clone(), name, rename.unwrap_or(name)),
 245                                 PathListMod { rename, .. } => {
 246                                     let name = match module_path.last() {
 247                                         Some(name) => *name,
 248                                         None => {
 249                                             resolve_error(
 250                                                 self,
 251                                                 source_item.span,
 252                                                 ResolutionError::
 253                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 254                                             );
 255                                             continue;
 256                                         }
 257                                     };
 258                                     let module_path = module_path.split_last().unwrap().1;
 259                                     let rename = rename.unwrap_or(name);
 260                                     (module_path.to_vec(), name, rename)
 261                                 }
 262                             };
 263                             self.build_import_directive(parent,
 264                                                         module_path,
 265                                                         SingleImport(rename, name),
 266                                                         source_item.span,
 267                                                         source_item.node.id(),
 268                                                         is_public,
 269                                                         shadowable);
 270                         }
 271                     }
 272                     ViewPathGlob(_) => {
 273                         self.build_import_directive(parent,
 274                                                     module_path,
 275                                                     GlobImport,
 276                                                     view_path.span,
 277                                                     item.id,
 278                                                     is_public,
 279                                                     shadowable);
 280                     }
 281                 }
 282                 parent
 283             }
 284
 285             ItemExternCrate(_) => {
 286                 // n.b. we don't need to look at the path option here, because cstore already
 287                 // did
 288                 if let Some(crate_id) = self.session.cstore.extern_mod_stmt_cnum(item.id) {
 289                     let def_id = DefId {
 290                         krate: crate_id,
 291                         index: CRATE_DEF_INDEX,
 292                     };
 293                     self.external_exports.insert(def_id);
 294                     let parent_link = ModuleParentLink(parent, name);
 295                     let def = Def::Mod(def_id);
 296                     let external_module = self.new_extern_crate_module(parent_link, def);
 297                     self.define(parent, name, TypeNS, (external_module, sp));
 298
 299                     self.build_reduced_graph_for_external_crate(external_module);
 300                 }
 301                 parent
 302             }
 303
 304             ItemMod(..) => {
 305                 let parent_link = ModuleParentLink(parent, name);
 306                 let def = Def::Mod(self.ast_map.local_def_id(item.id));
 307                 let module = self.new_module(parent_link, Some(def), false, is_public);
 308                 self.define(parent, name, TypeNS, (module, sp));
 309                 parent.module_children.borrow_mut().insert(item.id, module);
 310                 module
 311             }
 312
 313             ItemForeignMod(..) => parent,
 314
 315             // These items live in the value namespace.
 316             ItemStatic(_, m, _) => {
 317                 let mutbl = m == hir::MutMutable;
 318                 let def = Def::Static(self.ast_map.local_def_id(item.id), mutbl);
 319                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 320                 parent
 321             }
 322             ItemConst(_, _) => {
 323                 let def = Def::Const(self.ast_map.local_def_id(item.id));
 324                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 325                 parent
 326             }
 327             ItemFn(_, _, _, _, _, _) => {
 328                 let def = Def::Fn(self.ast_map.local_def_id(item.id));
 329                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 330                 parent
 331             }
 332
 333             // These items live in the type namespace.
 334             ItemTy(..) => {
 335                 let parent_link = ModuleParentLink(parent, name);
 336                 let def = Def::TyAlias(self.ast_map.local_def_id(item.id));
 337                 let module = self.new_module(parent_link, Some(def), false, is_public);
 338                 self.define(parent, name, TypeNS, (module, sp));
 339                 parent
 340             }
 341
 342             ItemEnum(ref enum_definition, _) => {
 343                 let parent_link = ModuleParentLink(parent, name);
 344                 let def = Def::Enum(self.ast_map.local_def_id(item.id));
 345                 let module = self.new_module(parent_link, Some(def), false, is_public);
 346                 self.define(parent, name, TypeNS, (module, sp));
 347
 348                 let variant_modifiers = if is_public {
 349                     DefModifiers::empty()
 350                 } else {
 351                     DefModifiers::PRIVATE_VARIANT
 352                 };
 353                 for variant in &(*enum_definition).variants {
 354                     let item_def_id = self.ast_map.local_def_id(item.id);
 355                     self.build_reduced_graph_for_variant(variant, item_def_id,
 356                                                          module, variant_modifiers);
 357                 }
 358                 parent
 359             }
 360
 361             // These items live in both the type and value namespaces.
 362             ItemStruct(ref struct_def, _) => {
 363                 // Define a name in the type namespace.
 364                 let def = Def::Struct(self.ast_map.local_def_id(item.id));
 365                 self.define(parent, name, TypeNS, (def, sp, modifiers));
 366
 367                 // If this is a newtype or unit-like struct, define a name
 368                 // in the value namespace as well
 369                 if !struct_def.is_struct() {
 370                     let def = Def::Struct(self.ast_map.local_def_id(struct_def.id()));
 371                     self.define(parent, name, ValueNS, (def, sp, modifiers));
 372                 }
 373
 374                 // Record the def ID and fields of this struct.
 375                 let named_fields = struct_def.fields()
 376                                              .iter()
 377                                              .filter_map(|f| {
 378                                                  match f.node.kind {
 379                                                      NamedField(name, _) => Some(name),
 380                                                      UnnamedField(_) => None,
 381                                                  }
 382                                              })
 383                                              .collect();
 384                 let item_def_id = self.ast_map.local_def_id(item.id);
 385                 self.structs.insert(item_def_id, named_fields);
 386
 387                 parent
 388             }
 389
 390             ItemDefaultImpl(_, _) |
 391             ItemImpl(..) => parent,
 392
 393             ItemTrait(_, _, _, ref items) => {
 394                 let def_id = self.ast_map.local_def_id(item.id);
 395
 396                 // Add all the items within to a new module.
 397                 let parent_link = ModuleParentLink(parent, name);
 398                 let def = Def::Trait(def_id);
 399                 let module_parent = self.new_module(parent_link, Some(def), false, is_public);
 400                 self.define(parent, name, TypeNS, (module_parent, sp));
 401
 402                 // Add the names of all the items to the trait info.
 403                 for item in items {
 404                     let item_def_id = self.ast_map.local_def_id(item.id);
 405                     let (def, ns) = match item.node {
 406                         hir::ConstTraitItem(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 407                         hir::MethodTraitItem(..) => (Def::Method(item_def_id), ValueNS),
 408                         hir::TypeTraitItem(..) => (Def::AssociatedTy(def_id, item_def_id), TypeNS),
 409                     };
 410
 411                     let modifiers = DefModifiers::PUBLIC; // NB: not DefModifiers::IMPORTABLE
 412                     self.define(module_parent, item.name, ns, (def, item.span, modifiers));
 413
 414                     self.trait_item_map.insert((item.name, def_id), item_def_id);
 415                 }
 416
 417                 parent
 418             }
 419         }
 420     }
 421
 422     // Constructs the reduced graph for one variant. Variants exist in the
 423     // type and value namespaces.
 424     fn build_reduced_graph_for_variant(&mut self,
 425                                        variant: &Variant,
 426                                        item_id: DefId,
 427                                        parent: Module<'b>,
 428                                        variant_modifiers: DefModifiers) {
 429         let name = variant.node.name;
 430         if variant.node.data.is_struct() {
 431             // Not adding fields for variants as they are not accessed with a self receiver
 432             let variant_def_id = self.ast_map.local_def_id(variant.node.data.id());
 433             self.structs.insert(variant_def_id, Vec::new());
 434         }
 435
 436         // Variants are always treated as importable to allow them to be glob used.
 437         // All variants are defined in both type and value namespaces as future-proofing.
 438         let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE | variant_modifiers;
 439         let def = Def::Variant(item_id, self.ast_map.local_def_id(variant.node.data.id()));
 440
 441         self.define(parent, name, ValueNS, (def, variant.span, modifiers));
 442         self.define(parent, name, TypeNS, (def, variant.span, modifiers));
 443     }
 444
 445     /// Constructs the reduced graph for one foreign item.
 446     fn build_reduced_graph_for_foreign_item(&mut self,
 447                                             foreign_item: &ForeignItem,
 448                                             parent: Module<'b>) {
 449         let name = foreign_item.name;
 450         let is_public = foreign_item.vis == hir::Public;
 451         let modifiers = if is_public {
 452             DefModifiers::PUBLIC
 453         } else {
 454             DefModifiers::empty()
 455         } | DefModifiers::IMPORTABLE;
 456
 457         let def = match foreign_item.node {
 458             ForeignItemFn(..) => {
 459                 Def::Fn(self.ast_map.local_def_id(foreign_item.id))
 460             }
 461             ForeignItemStatic(_, m) => {
 462                 Def::Static(self.ast_map.local_def_id(foreign_item.id), m)
 463             }
 464         };
 465         self.define(parent, name, ValueNS, (def, foreign_item.span, modifiers));
 466     }
 467
 468     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: Module<'b>) -> Module<'b> {
 469         if self.block_needs_anonymous_module(block) {
 470             let block_id = block.id;
 471
 472             debug!("(building reduced graph for block) creating a new anonymous module for block \
 473                     {}",
 474                    block_id);
 475
 476             let parent_link = BlockParentLink(parent, block_id);
 477             let new_module = self.new_module(parent_link, None, false, false);
 478             parent.module_children.borrow_mut().insert(block_id, new_module);
 479             new_module
 480         } else {
 481             parent
 482         }
 483     }
 484
 485     fn handle_external_def(&mut self,
 486                            def: Def,
 487                            vis: Visibility,
 488                            final_ident: &str,
 489                            name: Name,
 490                            new_parent: Module<'b>) {
 491         debug!("(building reduced graph for external crate) building external def {}, priv {:?}",
 492                final_ident,
 493                vis);
 494         let is_public = vis == hir::Public;
 495
 496         let mut modifiers = DefModifiers::empty();
 497         if is_public {
 498             modifiers = modifiers | DefModifiers::PUBLIC;
 499         }
 500         if new_parent.is_normal() {
 501             modifiers = modifiers | DefModifiers::IMPORTABLE;
 502         }
 503
 504         let is_exported = is_public &&
 505                           match new_parent.def_id() {
 506             None => true,
 507             Some(did) => self.external_exports.contains(&did),
 508         };
 509         if is_exported {
 510             self.external_exports.insert(def.def_id());
 511         }
 512
 513         match def {
 514             Def::Mod(_) | Def::ForeignMod(_) | Def::Enum(..) | Def::TyAlias(..) => {
 515                 debug!("(building reduced graph for external crate) building module {} {}",
 516                        final_ident,
 517                        is_public);
 518                 let parent_link = ModuleParentLink(new_parent, name);
 519                 let module = self.new_module(parent_link, Some(def), true, is_public);
 520                 self.try_define(new_parent, name, TypeNS, (module, DUMMY_SP));
 521             }
 522             Def::Variant(_, variant_id) => {
 523                 debug!("(building reduced graph for external crate) building variant {}",
 524                        final_ident);
 525                 // Variants are always treated as importable to allow them to be glob used.
 526                 // All variants are defined in both type and value namespaces as future-proofing.
 527                 let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 528                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 529                 self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 530                 if self.session.cstore.variant_kind(variant_id) == Some(VariantKind::Struct) {
 531                     // Not adding fields for variants as they are not accessed with a self receiver
 532                     self.structs.insert(variant_id, Vec::new());
 533                 }
 534             }
 535             Def::Fn(..) |
 536             Def::Static(..) |
 537             Def::Const(..) |
 538             Def::AssociatedConst(..) |
 539             Def::Method(..) => {
 540                 debug!("(building reduced graph for external crate) building value (fn/static) {}",
 541                        final_ident);
 542                 self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 543             }
 544             Def::Trait(def_id) => {
 545                 debug!("(building reduced graph for external crate) building type {}",
 546                        final_ident);
 547
 548                 // If this is a trait, add all the trait item names to the trait
 549                 // info.
 550
 551                 let trait_item_def_ids = self.session.cstore.trait_item_def_ids(def_id);
 552                 for trait_item_def in &trait_item_def_ids {
 553                     let trait_item_name =
 554                         self.session.cstore.item_name(trait_item_def.def_id());
 555
 556                     debug!("(building reduced graph for external crate) ... adding trait item \
 557                             '{}'",
 558                            trait_item_name);
 559
 560                     self.trait_item_map.insert((trait_item_name, def_id), trait_item_def.def_id());
 561
 562                     if is_exported {
 563                         self.external_exports.insert(trait_item_def.def_id());
 564                     }
 565                 }
 566
 567                 let parent_link = ModuleParentLink(new_parent, name);
 568                 let module = self.new_module(parent_link, Some(def), true, is_public);
 569                 self.try_define(new_parent, name, TypeNS, (module, DUMMY_SP));
 570             }
 571             Def::AssociatedTy(..) => {
 572                 debug!("(building reduced graph for external crate) building type {}",
 573                        final_ident);
 574                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 575             }
 576             Def::Struct(def_id)
 577                 if self.session.cstore.tuple_struct_definition_if_ctor(def_id).is_none() => {
 578                 debug!("(building reduced graph for external crate) building type and value for \
 579                         {}",
 580                        final_ident);
 581                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 582                 if let Some(ctor_def_id) = self.session.cstore.struct_ctor_def_id(def_id) {
 583                     let def = Def::Struct(ctor_def_id);
 584                     self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 585                 }
 586
 587                 // Record the def ID and fields of this struct.
 588                 let fields = self.session.cstore.struct_field_names(def_id);
 589                 self.structs.insert(def_id, fields);
 590             }
 591             Def::Struct(..) => {}
 592             Def::Local(..) |
 593             Def::PrimTy(..) |
 594             Def::TyParam(..) |
 595             Def::Upvar(..) |
 596             Def::Label(..) |
 597             Def::SelfTy(..) |
 598             Def::Err => {
 599                 panic!("didn't expect `{:?}`", def);
 600             }
 601         }
 602     }
 603
 604     /// Builds the reduced graph for a single item in an external crate.
 605     fn build_reduced_graph_for_external_crate_def(&mut self,
 606                                                   root: Module<'b>,
 607                                                   xcdef: ChildItem) {
 608         match xcdef.def {
 609             DlDef(def) => {
 610                 // Add the new child item, if necessary.
 611                 match def {
 612                     Def::ForeignMod(def_id) => {
 613                         // Foreign modules have no names. Recur and populate
 614                         // eagerly.
 615                         for child in self.session.cstore.item_children(def_id) {
 616                             self.build_reduced_graph_for_external_crate_def(root, child)
 617                         }
 618                     }
 619                     _ => {
 620                         self.handle_external_def(def,
 621                                                  xcdef.vis,
 622                                                  &xcdef.name.as_str(),
 623                                                  xcdef.name,
 624                                                  root);
 625                     }
 626                 }
 627             }
 628             DlImpl(_) => {
 629                 debug!("(building reduced graph for external crate) ignoring impl");
 630             }
 631             DlField => {
 632                 debug!("(building reduced graph for external crate) ignoring field");
 633             }
 634         }
 635     }
 636
 637     /// Builds the reduced graph rooted at the given external module.
 638     fn populate_external_module(&mut self, module: Module<'b>) {
 639         debug!("(populating external module) attempting to populate {}",
 640                module_to_string(module));
 641
 642         let def_id = match module.def_id() {
 643             None => {
 644                 debug!("(populating external module) ... no def ID!");
 645                 return;
 646             }
 647             Some(def_id) => def_id,
 648         };
 649
 650         for child in self.session.cstore.item_children(def_id) {
 651             debug!("(populating external module) ... found ident: {}",
 652                    child.name);
 653             self.build_reduced_graph_for_external_crate_def(module, child);
 654         }
 655         module.populated.set(true)
 656     }
 657
 658     /// Ensures that the reduced graph rooted at the given external module
 659     /// is built, building it if it is not.
 660     fn populate_module_if_necessary(&mut self, module: Module<'b>) {
 661         if !module.populated.get() {
 662             self.populate_external_module(module)
 663         }
 664         assert!(module.populated.get())
 665     }
 666
 667     /// Builds the reduced graph rooted at the 'use' directive for an external
 668     /// crate.
 669     fn build_reduced_graph_for_external_crate(&mut self, root: Module<'b>) {
 670         let root_cnum = root.def_id().unwrap().krate;
 671         for child in self.session.cstore.crate_top_level_items(root_cnum) {
 672             self.build_reduced_graph_for_external_crate_def(root, child);
 673         }
 674     }
 675
 676     /// Creates and adds an import directive to the given module.
 677     fn build_import_directive(&mut self,
 678                               module_: Module<'b>,
 679                               module_path: Vec<Name>,
 680                               subclass: ImportDirectiveSubclass,
 681                               span: Span,
 682                               id: NodeId,
 683                               is_public: bool,
 684                               shadowable: Shadowable) {
 685         module_.unresolved_imports
 686                .borrow_mut()
 687                .push(ImportDirective::new(module_path, subclass, span, id, is_public, shadowable));
 688         self.unresolved_imports += 1;
 689
 690         if is_public {
 691             module_.inc_pub_count();
 692         }
 693
 694         // Bump the reference count on the name. Or, if this is a glob, set
 695         // the appropriate flag.
 696
 697         match subclass {
 698             SingleImport(target, _) => {
 699                 module_.increment_outstanding_references_for(target, ValueNS);
 700                 module_.increment_outstanding_references_for(target, TypeNS);
 701             }
 702             GlobImport => {
 703                 // Set the glob flag. This tells us that we don't know the
 704                 // module's exports ahead of time.
 705
 706                 module_.inc_glob_count();
 707                 if is_public {
 708                     module_.inc_pub_glob_count();
 709                 }
 710             }
 711         }
 712     }
 713 }
 714
 715 struct BuildReducedGraphVisitor<'a, 'b: 'a, 'tcx: 'b> {
 716     builder: GraphBuilder<'a, 'b, 'tcx>,
 717     parent: Module<'b>,
 718 }
 719
 720 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 721     fn visit_nested_item(&mut self, item: hir::ItemId) {
 722         self.visit_item(self.builder.resolver.ast_map.expect_item(item.id))
 723     }
 724
 725     fn visit_item(&mut self, item: &Item) {
 726         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 727         let old_parent = replace(&mut self.parent, p);
 728         intravisit::walk_item(self, item);
 729         self.parent = old_parent;
 730     }
 731
 732     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 733         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 734     }
 735
 736     fn visit_block(&mut self, block: &Block) {
 737         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 738         let old_parent = replace(&mut self.parent, np);
 739         intravisit::walk_block(self, block);
 740         self.parent = old_parent;
 741     }
 742 }
 743
 744 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &hir::Crate) {
 745     GraphBuilder { resolver: resolver }.build_reduced_graph(krate);
 746 }
 747
 748 pub fn populate_module_if_necessary<'a, 'tcx>(resolver: &mut Resolver<'a, 'tcx>,
 749                                               module: Module<'a>) {
 750     GraphBuilder { resolver: resolver }.populate_module_if_necessary(module);
 751 }