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 Namespace::{self, TypeNS, ValueNS};
  22 use {NameBinding, DefOrModule};
  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 rustc::middle::cstore::{CrateStore, ChildItem, DlDef, DlField, DlImpl};
  30 use rustc::middle::def::*;
  31 use rustc::middle::def_id::{CRATE_DEF_INDEX, DefId};
  32 use rustc::middle::ty::VariantKind;
  33
  34 use syntax::ast::{Name, NodeId};
  35 use syntax::attr::AttrMetaMethods;
  36 use syntax::parse::token::special_idents;
  37 use syntax::codemap::{Span, DUMMY_SP};
  38
  39 use rustc_front::hir;
  40 use rustc_front::hir::{Block, DeclItem};
  41 use rustc_front::hir::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  42 use rustc_front::hir::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  43 use rustc_front::hir::{ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  44 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  45 use rustc_front::hir::{NamedField, PathListIdent, PathListMod};
  46 use rustc_front::hir::StmtDecl;
  47 use rustc_front::hir::UnnamedField;
  48 use rustc_front::hir::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  49 use rustc_front::hir::Visibility;
  50 use rustc_front::intravisit::{self, Visitor};
  51
  52 use std::mem::replace;
  53 use std::ops::{Deref, DerefMut};
  54
  55 struct GraphBuilder<'a, 'b: 'a, 'tcx: 'b> {
  56     resolver: &'a mut Resolver<'b, 'tcx>,
  57 }
  58
  59 impl<'a, 'b:'a, 'tcx:'b> Deref for GraphBuilder<'a, 'b, 'tcx> {
  60     type Target = Resolver<'b, 'tcx>;
  61
  62     fn deref(&self) -> &Resolver<'b, 'tcx> {
  63         &*self.resolver
  64     }
  65 }
  66
  67 impl<'a, 'b:'a, 'tcx:'b> DerefMut for GraphBuilder<'a, 'b, 'tcx> {
  68     fn deref_mut(&mut self) -> &mut Resolver<'b, 'tcx> {
  69         &mut *self.resolver
  70     }
  71 }
  72
  73 trait ToNameBinding<'a> {
  74     fn to_name_binding(self) -> NameBinding<'a>;
  75 }
  76
  77 impl<'a> ToNameBinding<'a> for (Module<'a>, Span) {
  78     fn to_name_binding(self) -> NameBinding<'a> {
  79         NameBinding::create_from_module(self.0, Some(self.1))
  80     }
  81 }
  82
  83 impl<'a> ToNameBinding<'a> for (Def, Span, DefModifiers) {
  84     fn to_name_binding(self) -> NameBinding<'a> {
  85         let def = DefOrModule::Def(self.0);
  86         NameBinding { modifiers: self.2, def_or_module: def, span: Some(self.1) }
  87     }
  88 }
  89
  90 impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
  91     /// Constructs the reduced graph for the entire crate.
  92     fn build_reduced_graph(self, krate: &hir::Crate) {
  93         let mut visitor = BuildReducedGraphVisitor {
  94             parent: self.graph_root,
  95             builder: self,
  96         };
  97         intravisit::walk_crate(&mut visitor, krate);
  98     }
  99
 100     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined.
 101     fn try_define<T>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T)
 102         where T: ToNameBinding<'b>
 103     {
 104         parent.try_define_child(name, ns, def.to_name_binding());
 105     }
 106
 107     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
 108     /// otherwise, reports an error.
 109     fn define<T: ToNameBinding<'b>>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T) {
 110         let binding = def.to_name_binding();
 111         let old_binding = match parent.try_define_child(name, ns, binding.clone()) {
 112             Some(old_binding) => old_binding,
 113             None => return,
 114         };
 115
 116         let span = binding.span.unwrap_or(DUMMY_SP);
 117         if !old_binding.is_extern_crate() && !binding.is_extern_crate() {
 118             // Record an error here by looking up the namespace that had the duplicate
 119             let ns_str = match ns { TypeNS => "type or module", ValueNS => "value" };
 120             let resolution_error = ResolutionError::DuplicateDefinition(ns_str, name);
 121             let mut err = resolve_struct_error(self, span, resolution_error);
 122
 123             if let Some(sp) = old_binding.span {
 124                 let note = format!("first definition of {} `{}` here", ns_str, name);
 125                 err.span_note(sp, &note);
 126             }
 127             err.emit();
 128         } else if old_binding.is_extern_crate() && binding.is_extern_crate() {
 129             span_err!(self.session,
 130                       span,
 131                       E0259,
 132                       "an external crate named `{}` has already been imported into this module",
 133                       name);
 134         } else {
 135             span_err!(self.session,
 136                       span,
 137                       E0260,
 138                       "the name `{}` conflicts with an external crate \
 139                       that has been imported into this module",
 140                       name);
 141         }
 142     }
 143
 144     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 145         // Check each statement.
 146         for statement in &block.stmts {
 147             match statement.node {
 148                 StmtDecl(ref declaration, _) => {
 149                     match declaration.node {
 150                         DeclItem(_) => {
 151                             return true;
 152                         }
 153                         _ => {
 154                             // Keep searching.
 155                         }
 156                     }
 157                 }
 158                 _ => {
 159                     // Keep searching.
 160                 }
 161             }
 162         }
 163
 164         // If we found no items, we don't need to create
 165         // an anonymous module.
 166
 167         return false;
 168     }
 169
 170     /// Constructs the reduced graph for one item.
 171     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: Module<'b>) -> Module<'b> {
 172         let name = item.name;
 173         let sp = item.span;
 174         let is_public = item.vis == hir::Public;
 175         let modifiers = if is_public {
 176             DefModifiers::PUBLIC
 177         } else {
 178             DefModifiers::empty()
 179         } | DefModifiers::IMPORTABLE;
 180
 181         match item.node {
 182             ItemUse(ref view_path) => {
 183                 // Extract and intern the module part of the path. For
 184                 // globs and lists, the path is found directly in the AST;
 185                 // for simple paths we have to munge the path a little.
 186                 let module_path = match view_path.node {
 187                     ViewPathSimple(_, ref full_path) => {
 188                         full_path.segments
 189                                  .split_last()
 190                                  .unwrap()
 191                                  .1
 192                                  .iter()
 193                                  .map(|seg| seg.identifier.name)
 194                                  .collect()
 195                     }
 196
 197                     ViewPathGlob(ref module_ident_path) |
 198                     ViewPathList(ref module_ident_path, _) => {
 199                         module_ident_path.segments
 200                                          .iter()
 201                                          .map(|seg| seg.identifier.name)
 202                                          .collect()
 203                     }
 204                 };
 205
 206                 // Build up the import directives.
 207                 let shadowable = item.attrs.iter().any(|attr| {
 208                     attr.name() == special_idents::prelude_import.name.as_str()
 209                 });
 210                 let shadowable = if shadowable {
 211                     Shadowable::Always
 212                 } else {
 213                     Shadowable::Never
 214                 };
 215
 216                 match view_path.node {
 217                     ViewPathSimple(binding, ref full_path) => {
 218                         let source_name = full_path.segments.last().unwrap().identifier.name;
 219                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 220                             resolve_error(self,
 221                                           view_path.span,
 222                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 223                         }
 224
 225                         let subclass = SingleImport(binding, source_name);
 226                         self.build_import_directive(parent,
 227                                                     module_path,
 228                                                     subclass,
 229                                                     view_path.span,
 230                                                     item.id,
 231                                                     is_public,
 232                                                     shadowable);
 233                     }
 234                     ViewPathList(_, ref source_items) => {
 235                         // Make sure there's at most one `mod` import in the list.
 236                         let mod_spans = source_items.iter()
 237                                                     .filter_map(|item| {
 238                                                         match item.node {
 239                                                             PathListMod { .. } => Some(item.span),
 240                                                             _ => None,
 241                                                         }
 242                                                     })
 243                                                     .collect::<Vec<Span>>();
 244                         if mod_spans.len() > 1 {
 245                             let mut e = resolve_struct_error(self,
 246                                           mod_spans[0],
 247                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 248                             for other_span in mod_spans.iter().skip(1) {
 249                                 e.span_note(*other_span, "another `self` import appears here");
 250                             }
 251                             e.emit();
 252                         }
 253
 254                         for source_item in source_items {
 255                             let (module_path, name, rename) = match source_item.node {
 256                                 PathListIdent { name, rename, .. } =>
 257                                     (module_path.clone(), name, rename.unwrap_or(name)),
 258                                 PathListMod { rename, .. } => {
 259                                     let name = match module_path.last() {
 260                                         Some(name) => *name,
 261                                         None => {
 262                                             resolve_error(
 263                                                 self,
 264                                                 source_item.span,
 265                                                 ResolutionError::
 266                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 267                                             );
 268                                             continue;
 269                                         }
 270                                     };
 271                                     let module_path = module_path.split_last().unwrap().1;
 272                                     let rename = rename.unwrap_or(name);
 273                                     (module_path.to_vec(), name, rename)
 274                                 }
 275                             };
 276                             self.build_import_directive(parent,
 277                                                         module_path,
 278                                                         SingleImport(rename, name),
 279                                                         source_item.span,
 280                                                         source_item.node.id(),
 281                                                         is_public,
 282                                                         shadowable);
 283                         }
 284                     }
 285                     ViewPathGlob(_) => {
 286                         self.build_import_directive(parent,
 287                                                     module_path,
 288                                                     GlobImport,
 289                                                     view_path.span,
 290                                                     item.id,
 291                                                     is_public,
 292                                                     shadowable);
 293                     }
 294                 }
 295                 parent
 296             }
 297
 298             ItemExternCrate(_) => {
 299                 // n.b. we don't need to look at the path option here, because cstore already
 300                 // did
 301                 if let Some(crate_id) = self.session.cstore.extern_mod_stmt_cnum(item.id) {
 302                     let def_id = DefId {
 303                         krate: crate_id,
 304                         index: CRATE_DEF_INDEX,
 305                     };
 306                     self.external_exports.insert(def_id);
 307                     let parent_link = ModuleParentLink(parent, name);
 308                     let def = Def::Mod(def_id);
 309                     let external_module = self.new_extern_crate_module(parent_link, def);
 310                     self.define(parent, name, TypeNS, (external_module, sp));
 311
 312                     self.build_reduced_graph_for_external_crate(&external_module);
 313                 }
 314                 parent
 315             }
 316
 317             ItemMod(..) => {
 318                 let parent_link = ModuleParentLink(parent, name);
 319                 let def = Def::Mod(self.ast_map.local_def_id(item.id));
 320                 let module = self.new_module(parent_link, Some(def), false, is_public);
 321                 self.define(parent, name, TypeNS, (module, sp));
 322                 module
 323             }
 324
 325             ItemForeignMod(..) => parent,
 326
 327             // These items live in the value namespace.
 328             ItemStatic(_, m, _) => {
 329                 let mutbl = m == hir::MutMutable;
 330                 let def = Def::Static(self.ast_map.local_def_id(item.id), mutbl);
 331                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 332                 parent
 333             }
 334             ItemConst(_, _) => {
 335                 let def = Def::Const(self.ast_map.local_def_id(item.id));
 336                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 337                 parent
 338             }
 339             ItemFn(_, _, _, _, _, _) => {
 340                 let def = Def::Fn(self.ast_map.local_def_id(item.id));
 341                 self.define(parent, name, ValueNS, (def, sp, modifiers));
 342                 parent
 343             }
 344
 345             // These items live in the type namespace.
 346             ItemTy(..) => {
 347                 let parent_link = ModuleParentLink(parent, name);
 348                 let def = Def::TyAlias(self.ast_map.local_def_id(item.id));
 349                 let module = self.new_module(parent_link, Some(def), false, is_public);
 350                 self.define(parent, name, TypeNS, (module, sp));
 351                 parent
 352             }
 353
 354             ItemEnum(ref enum_definition, _) => {
 355                 let parent_link = ModuleParentLink(parent, name);
 356                 let def = Def::Enum(self.ast_map.local_def_id(item.id));
 357                 let module = self.new_module(parent_link, Some(def), false, is_public);
 358                 self.define(parent, name, TypeNS, (module, sp));
 359
 360                 let variant_modifiers = if is_public {
 361                     DefModifiers::empty()
 362                 } else {
 363                     DefModifiers::PRIVATE_VARIANT
 364                 };
 365                 for variant in &(*enum_definition).variants {
 366                     let item_def_id = self.ast_map.local_def_id(item.id);
 367                     self.build_reduced_graph_for_variant(variant, item_def_id,
 368                                                          &module, variant_modifiers);
 369                 }
 370                 parent
 371             }
 372
 373             // These items live in both the type and value namespaces.
 374             ItemStruct(ref struct_def, _) => {
 375                 // Define a name in the type namespace.
 376                 let def = Def::Struct(self.ast_map.local_def_id(item.id));
 377                 self.define(parent, name, TypeNS, (def, sp, modifiers));
 378
 379                 // If this is a newtype or unit-like struct, define a name
 380                 // in the value namespace as well
 381                 if !struct_def.is_struct() {
 382                     let def = Def::Struct(self.ast_map.local_def_id(struct_def.id()));
 383                     self.define(parent, name, ValueNS, (def, sp, modifiers));
 384                 }
 385
 386                 // Record the def ID and fields of this struct.
 387                 let named_fields = struct_def.fields()
 388                                              .iter()
 389                                              .filter_map(|f| {
 390                                                  match f.node.kind {
 391                                                      NamedField(name, _) => Some(name),
 392                                                      UnnamedField(_) => None,
 393                                                  }
 394                                              })
 395                                              .collect();
 396                 let item_def_id = self.ast_map.local_def_id(item.id);
 397                 self.structs.insert(item_def_id, named_fields);
 398
 399                 parent
 400             }
 401
 402             ItemDefaultImpl(_, _) |
 403             ItemImpl(..) => parent,
 404
 405             ItemTrait(_, _, _, ref items) => {
 406                 let def_id = self.ast_map.local_def_id(item.id);
 407
 408                 // Add all the items within to a new module.
 409                 let parent_link = ModuleParentLink(parent, name);
 410                 let def = Def::Trait(def_id);
 411                 let module_parent = self.new_module(parent_link, Some(def), false, is_public);
 412                 self.define(parent, name, TypeNS, (module_parent, sp));
 413
 414                 // Add the names of all the items to the trait info.
 415                 for item in items {
 416                     let item_def_id = self.ast_map.local_def_id(item.id);
 417                     let (def, ns) = match item.node {
 418                         hir::ConstTraitItem(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 419                         hir::MethodTraitItem(..) => (Def::Method(item_def_id), ValueNS),
 420                         hir::TypeTraitItem(..) => (Def::AssociatedTy(def_id, item_def_id), TypeNS),
 421                     };
 422
 423                     let modifiers = DefModifiers::PUBLIC; // NB: not DefModifiers::IMPORTABLE
 424                     self.define(&module_parent, item.name, ns, (def, item.span, modifiers));
 425
 426                     self.trait_item_map.insert((item.name, def_id), item_def_id);
 427                 }
 428
 429                 parent
 430             }
 431         }
 432     }
 433
 434     // Constructs the reduced graph for one variant. Variants exist in the
 435     // type and value namespaces.
 436     fn build_reduced_graph_for_variant(&mut self,
 437                                        variant: &Variant,
 438                                        item_id: DefId,
 439                                        parent: Module<'b>,
 440                                        variant_modifiers: DefModifiers) {
 441         let name = variant.node.name;
 442         if variant.node.data.is_struct() {
 443             // Not adding fields for variants as they are not accessed with a self receiver
 444             let variant_def_id = self.ast_map.local_def_id(variant.node.data.id());
 445             self.structs.insert(variant_def_id, Vec::new());
 446         }
 447
 448         // Variants are always treated as importable to allow them to be glob used.
 449         // All variants are defined in both type and value namespaces as future-proofing.
 450         let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE | variant_modifiers;
 451         let def = Def::Variant(item_id, self.ast_map.local_def_id(variant.node.data.id()));
 452
 453         self.define(parent, name, ValueNS, (def, variant.span, modifiers));
 454         self.define(parent, name, TypeNS, (def, variant.span, modifiers));
 455     }
 456
 457     /// Constructs the reduced graph for one foreign item.
 458     fn build_reduced_graph_for_foreign_item(&mut self,
 459                                             foreign_item: &ForeignItem,
 460                                             parent: Module<'b>) {
 461         let name = foreign_item.name;
 462         let is_public = foreign_item.vis == hir::Public;
 463         let modifiers = if is_public {
 464             DefModifiers::PUBLIC
 465         } else {
 466             DefModifiers::empty()
 467         } | DefModifiers::IMPORTABLE;
 468
 469         let def = match foreign_item.node {
 470             ForeignItemFn(..) => {
 471                 Def::Fn(self.ast_map.local_def_id(foreign_item.id))
 472             }
 473             ForeignItemStatic(_, m) => {
 474                 Def::Static(self.ast_map.local_def_id(foreign_item.id), m)
 475             }
 476         };
 477         self.define(parent, name, ValueNS, (def, foreign_item.span, modifiers));
 478     }
 479
 480     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: Module<'b>) -> Module<'b> {
 481         if self.block_needs_anonymous_module(block) {
 482             let block_id = block.id;
 483
 484             debug!("(building reduced graph for block) creating a new anonymous module for block \
 485                     {}",
 486                    block_id);
 487
 488             let parent_link = BlockParentLink(parent, block_id);
 489             let new_module = self.new_module(parent_link, None, false, false);
 490             parent.anonymous_children.borrow_mut().insert(block_id, new_module);
 491             new_module
 492         } else {
 493             parent
 494         }
 495     }
 496
 497     fn handle_external_def(&mut self,
 498                            def: Def,
 499                            vis: Visibility,
 500                            final_ident: &str,
 501                            name: Name,
 502                            new_parent: Module<'b>) {
 503         debug!("(building reduced graph for external crate) building external def {}, priv {:?}",
 504                final_ident,
 505                vis);
 506         let is_public = vis == hir::Public;
 507
 508         let mut modifiers = DefModifiers::empty();
 509         if is_public {
 510             modifiers = modifiers | DefModifiers::PUBLIC;
 511         }
 512         if new_parent.is_normal() {
 513             modifiers = modifiers | DefModifiers::IMPORTABLE;
 514         }
 515
 516         let is_exported = is_public &&
 517                           match new_parent.def_id() {
 518             None => true,
 519             Some(did) => self.external_exports.contains(&did),
 520         };
 521         if is_exported {
 522             self.external_exports.insert(def.def_id());
 523         }
 524
 525         match def {
 526             Def::Mod(_) | Def::ForeignMod(_) | Def::Enum(..) | Def::TyAlias(..) => {
 527                 debug!("(building reduced graph for external crate) building module {} {}",
 528                        final_ident,
 529                        is_public);
 530                 let parent_link = ModuleParentLink(new_parent, name);
 531                 let module = self.new_module(parent_link, Some(def), true, is_public);
 532                 self.try_define(new_parent, name, TypeNS, (module, DUMMY_SP));
 533             }
 534             Def::Variant(_, variant_id) => {
 535                 debug!("(building reduced graph for external crate) building variant {}",
 536                        final_ident);
 537                 // Variants are always treated as importable to allow them to be glob used.
 538                 // All variants are defined in both type and value namespaces as future-proofing.
 539                 let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 540                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 541                 self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 542                 if self.session.cstore.variant_kind(variant_id) == Some(VariantKind::Struct) {
 543                     // Not adding fields for variants as they are not accessed with a self receiver
 544                     self.structs.insert(variant_id, Vec::new());
 545                 }
 546             }
 547             Def::Fn(..) |
 548             Def::Static(..) |
 549             Def::Const(..) |
 550             Def::AssociatedConst(..) |
 551             Def::Method(..) => {
 552                 debug!("(building reduced graph for external crate) building value (fn/static) {}",
 553                        final_ident);
 554                 self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 555             }
 556             Def::Trait(def_id) => {
 557                 debug!("(building reduced graph for external crate) building type {}",
 558                        final_ident);
 559
 560                 // If this is a trait, add all the trait item names to the trait
 561                 // info.
 562
 563                 let trait_item_def_ids = self.session.cstore.trait_item_def_ids(def_id);
 564                 for trait_item_def in &trait_item_def_ids {
 565                     let trait_item_name =
 566                         self.session.cstore.item_name(trait_item_def.def_id());
 567
 568                     debug!("(building reduced graph for external crate) ... adding trait item \
 569                             '{}'",
 570                            trait_item_name);
 571
 572                     self.trait_item_map.insert((trait_item_name, def_id), trait_item_def.def_id());
 573
 574                     if is_exported {
 575                         self.external_exports.insert(trait_item_def.def_id());
 576                     }
 577                 }
 578
 579                 let parent_link = ModuleParentLink(new_parent, name);
 580                 let module = self.new_module(parent_link, Some(def), true, is_public);
 581                 self.try_define(new_parent, name, TypeNS, (module, DUMMY_SP));
 582             }
 583             Def::AssociatedTy(..) => {
 584                 debug!("(building reduced graph for external crate) building type {}",
 585                        final_ident);
 586                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 587             }
 588             Def::Struct(def_id)
 589                 if self.session.cstore.tuple_struct_definition_if_ctor(def_id).is_none() => {
 590                 debug!("(building reduced graph for external crate) building type and value for \
 591                         {}",
 592                        final_ident);
 593                 self.try_define(new_parent, name, TypeNS, (def, DUMMY_SP, modifiers));
 594                 if let Some(ctor_def_id) = self.session.cstore.struct_ctor_def_id(def_id) {
 595                     let def = Def::Struct(ctor_def_id);
 596                     self.try_define(new_parent, name, ValueNS, (def, DUMMY_SP, modifiers));
 597                 }
 598
 599                 // Record the def ID and fields of this struct.
 600                 let fields = self.session.cstore.struct_field_names(def_id);
 601                 self.structs.insert(def_id, fields);
 602             }
 603             Def::Struct(..) => {}
 604             Def::Local(..) |
 605             Def::PrimTy(..) |
 606             Def::TyParam(..) |
 607             Def::Upvar(..) |
 608             Def::Label(..) |
 609             Def::SelfTy(..) |
 610             Def::Err => {
 611                 panic!("didn't expect `{:?}`", def);
 612             }
 613         }
 614     }
 615
 616     /// Builds the reduced graph for a single item in an external crate.
 617     fn build_reduced_graph_for_external_crate_def(&mut self,
 618                                                   root: Module<'b>,
 619                                                   xcdef: ChildItem) {
 620         match xcdef.def {
 621             DlDef(def) => {
 622                 // Add the new child item, if necessary.
 623                 match def {
 624                     Def::ForeignMod(def_id) => {
 625                         // Foreign modules have no names. Recur and populate
 626                         // eagerly.
 627                         for child in self.session.cstore.item_children(def_id) {
 628                             self.build_reduced_graph_for_external_crate_def(root, child)
 629                         }
 630                     }
 631                     _ => {
 632                         self.handle_external_def(def,
 633                                                  xcdef.vis,
 634                                                  &xcdef.name.as_str(),
 635                                                  xcdef.name,
 636                                                  root);
 637                     }
 638                 }
 639             }
 640             DlImpl(_) => {
 641                 debug!("(building reduced graph for external crate) ignoring impl");
 642             }
 643             DlField => {
 644                 debug!("(building reduced graph for external crate) ignoring field");
 645             }
 646         }
 647     }
 648
 649     /// Builds the reduced graph rooted at the given external module.
 650     fn populate_external_module(&mut self, module: Module<'b>) {
 651         debug!("(populating external module) attempting to populate {}",
 652                module_to_string(module));
 653
 654         let def_id = match module.def_id() {
 655             None => {
 656                 debug!("(populating external module) ... no def ID!");
 657                 return;
 658             }
 659             Some(def_id) => def_id,
 660         };
 661
 662         for child in self.session.cstore.item_children(def_id) {
 663             debug!("(populating external module) ... found ident: {}",
 664                    child.name);
 665             self.build_reduced_graph_for_external_crate_def(module, child);
 666         }
 667         module.populated.set(true)
 668     }
 669
 670     /// Ensures that the reduced graph rooted at the given external module
 671     /// is built, building it if it is not.
 672     fn populate_module_if_necessary(&mut self, module: Module<'b>) {
 673         if !module.populated.get() {
 674             self.populate_external_module(module)
 675         }
 676         assert!(module.populated.get())
 677     }
 678
 679     /// Builds the reduced graph rooted at the 'use' directive for an external
 680     /// crate.
 681     fn build_reduced_graph_for_external_crate(&mut self, root: Module<'b>) {
 682         let root_cnum = root.def_id().unwrap().krate;
 683         for child in self.session.cstore.crate_top_level_items(root_cnum) {
 684             self.build_reduced_graph_for_external_crate_def(root, child);
 685         }
 686     }
 687
 688     /// Creates and adds an import directive to the given module.
 689     fn build_import_directive(&mut self,
 690                               module_: Module<'b>,
 691                               module_path: Vec<Name>,
 692                               subclass: ImportDirectiveSubclass,
 693                               span: Span,
 694                               id: NodeId,
 695                               is_public: bool,
 696                               shadowable: Shadowable) {
 697         module_.imports
 698                .borrow_mut()
 699                .push(ImportDirective::new(module_path, subclass, span, id, is_public, shadowable));
 700         self.unresolved_imports += 1;
 701
 702         if is_public {
 703             module_.inc_pub_count();
 704         }
 705
 706         // Bump the reference count on the name. Or, if this is a glob, set
 707         // the appropriate flag.
 708
 709         match subclass {
 710             SingleImport(target, _) => {
 711                 debug!("(building import directive) building import directive: {}::{}",
 712                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 713                        target);
 714
 715                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 716                 for &ns in [TypeNS, ValueNS].iter() {
 717                     let mut resolution = import_resolutions.entry((target, ns)).or_insert(
 718                         ImportResolution::new(id, is_public)
 719                     );
 720
 721                     resolution.outstanding_references += 1;
 722                     // the source of this name is different now
 723                     resolution.id = id;
 724                     resolution.is_public = is_public;
 725                 }
 726             }
 727             GlobImport => {
 728                 // Set the glob flag. This tells us that we don't know the
 729                 // module's exports ahead of time.
 730
 731                 module_.inc_glob_count();
 732                 if is_public {
 733                     module_.inc_pub_glob_count();
 734                 }
 735             }
 736         }
 737     }
 738 }
 739
 740 struct BuildReducedGraphVisitor<'a, 'b: 'a, 'tcx: 'b> {
 741     builder: GraphBuilder<'a, 'b, 'tcx>,
 742     parent: Module<'b>,
 743 }
 744
 745 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 746     fn visit_nested_item(&mut self, item: hir::ItemId) {
 747         self.visit_item(self.builder.resolver.ast_map.expect_item(item.id))
 748     }
 749
 750     fn visit_item(&mut self, item: &Item) {
 751         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 752         let old_parent = replace(&mut self.parent, p);
 753         intravisit::walk_item(self, item);
 754         self.parent = old_parent;
 755     }
 756
 757     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 758         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 759     }
 760
 761     fn visit_block(&mut self, block: &Block) {
 762         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 763         let old_parent = replace(&mut self.parent, np);
 764         intravisit::walk_block(self, block);
 765         self.parent = old_parent;
 766     }
 767 }
 768
 769 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &hir::Crate) {
 770     GraphBuilder { resolver: resolver }.build_reduced_graph(krate);
 771 }
 772
 773 pub fn populate_module_if_necessary<'a, 'tcx>(resolver: &mut Resolver<'a, 'tcx>,
 774                                               module: Module<'a>) {
 775     GraphBuilder { resolver: resolver }.populate_module_if_necessary(module);
 776 }