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::{TypeNS, ValueNS};
  22 use NameBindings;
  23 use {names_to_string, module_to_string};
  24 use ParentLink::{self, ModuleParentLink, BlockParentLink};
  25 use Resolver;
  26 use resolve_imports::Shadowable;
  27 use {resolve_error, ResolutionError};
  28
  29 use self::DuplicateCheckingMode::*;
  30 use self::NamespaceError::*;
  31
  32 use rustc::metadata::csearch;
  33 use rustc::metadata::decoder::{DefLike, DlDef, DlField, DlImpl};
  34 use rustc::middle::def::*;
  35 use rustc::middle::def_id::{CRATE_DEF_INDEX, DefId};
  36
  37 use syntax::ast::{Name, NodeId};
  38 use syntax::attr::AttrMetaMethods;
  39 use syntax::parse::token::special_idents;
  40 use syntax::codemap::{Span, DUMMY_SP};
  41
  42 use rustc_front::hir;
  43 use rustc_front::hir::{Block, Crate, DeclItem};
  44 use rustc_front::hir::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  45 use rustc_front::hir::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  46 use rustc_front::hir::{ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  47 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  48 use rustc_front::hir::{NamedField, PathListIdent, PathListMod, Public};
  49 use rustc_front::hir::StmtDecl;
  50 use rustc_front::hir::UnnamedField;
  51 use rustc_front::hir::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  52 use rustc_front::hir::Visibility;
  53 use rustc_front::visit::{self, Visitor};
  54
  55 use std::mem::replace;
  56 use std::ops::{Deref, DerefMut};
  57 use std::rc::Rc;
  58
  59 // Specifies how duplicates should be handled when adding a child item if
  60 // another item exists with the same name in some namespace.
  61 #[derive(Copy, Clone, PartialEq)]
  62 enum DuplicateCheckingMode {
  63     ForbidDuplicateModules,
  64     ForbidDuplicateTypesAndModules,
  65     ForbidDuplicateValues,
  66     ForbidDuplicateTypesAndValues,
  67     OverwriteDuplicates,
  68 }
  69
  70 #[derive(Copy, Clone, PartialEq)]
  71 enum NamespaceError {
  72     NoError,
  73     ModuleError,
  74     TypeError,
  75     ValueError,
  76 }
  77
  78 fn namespace_error_to_string(ns: NamespaceError) -> &'static str {
  79     match ns {
  80         NoError => "",
  81         ModuleError | TypeError => "type or module",
  82         ValueError => "value",
  83     }
  84 }
  85
  86 struct GraphBuilder<'a, 'b: 'a, 'tcx: 'b> {
  87     resolver: &'a mut Resolver<'b, 'tcx>,
  88 }
  89
  90 impl<'a, 'b:'a, 'tcx:'b> Deref for GraphBuilder<'a, 'b, 'tcx> {
  91     type Target = Resolver<'b, 'tcx>;
  92
  93     fn deref(&self) -> &Resolver<'b, 'tcx> {
  94         &*self.resolver
  95     }
  96 }
  97
  98 impl<'a, 'b:'a, 'tcx:'b> DerefMut for GraphBuilder<'a, 'b, 'tcx> {
  99     fn deref_mut(&mut self) -> &mut Resolver<'b, 'tcx> {
 100         &mut *self.resolver
 101     }
 102 }
 103
 104 impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 105     /// Constructs the reduced graph for the entire crate.
 106     fn build_reduced_graph(self, krate: &hir::Crate) {
 107         let parent = self.graph_root.get_module();
 108         let mut visitor = BuildReducedGraphVisitor {
 109             builder: self,
 110             parent: parent,
 111         };
 112         visit::walk_crate(&mut visitor, krate);
 113     }
 114
 115     /// Adds a new child item to the module definition of the parent node and
 116     /// returns its corresponding name bindings as well as the current parent.
 117     /// Or, if we're inside a block, creates (or reuses) an anonymous module
 118     /// corresponding to the innermost block ID and returns the name bindings
 119     /// as well as the newly-created parent.
 120     ///
 121     /// # Panics
 122     ///
 123     /// Panics if this node does not have a module definition and we are not inside
 124     /// a block.
 125     fn add_child(&self,
 126                  name: Name,
 127                  parent: &Rc<Module>,
 128                  duplicate_checking_mode: DuplicateCheckingMode,
 129                  // For printing errors
 130                  sp: Span)
 131                  -> NameBindings {
 132         // If this is the immediate descendant of a module, then we add the
 133         // child name directly. Otherwise, we create or reuse an anonymous
 134         // module and add the child to that.
 135
 136         self.check_for_conflicts_between_external_crates_and_items(&**parent, name, sp);
 137
 138         // Add or reuse the child.
 139         let child = parent.children.borrow().get(&name).cloned();
 140         match child {
 141             None => {
 142                 let child = NameBindings::new();
 143                 parent.children.borrow_mut().insert(name, child.clone());
 144                 child
 145             }
 146             Some(child) => {
 147                 // Enforce the duplicate checking mode:
 148                 //
 149                 // * If we're requesting duplicate module checking, check that
 150                 //   there isn't a module in the module with the same name.
 151                 //
 152                 // * If we're requesting duplicate type checking, check that
 153                 //   there isn't a type in the module with the same name.
 154                 //
 155                 // * If we're requesting duplicate value checking, check that
 156                 //   there isn't a value in the module with the same name.
 157                 //
 158                 // * If we're requesting duplicate type checking and duplicate
 159                 //   value checking, check that there isn't a duplicate type
 160                 //   and a duplicate value with the same name.
 161                 //
 162                 // * If no duplicate checking was requested at all, do
 163                 //   nothing.
 164
 165                 let mut duplicate_type = NoError;
 166                 let ns = match duplicate_checking_mode {
 167                     ForbidDuplicateModules => {
 168                         if child.get_module_if_available().is_some() {
 169                             duplicate_type = ModuleError;
 170                         }
 171                         Some(TypeNS)
 172                     }
 173                     ForbidDuplicateTypesAndModules => {
 174                         if child.type_ns.defined() {
 175                             duplicate_type = TypeError;
 176                         }
 177                         Some(TypeNS)
 178                     }
 179                     ForbidDuplicateValues => {
 180                         if child.value_ns.defined() {
 181                             duplicate_type = ValueError;
 182                         }
 183                         Some(ValueNS)
 184                     }
 185                     ForbidDuplicateTypesAndValues => {
 186                         let mut n = None;
 187                         match child.type_ns.def() {
 188                             Some(DefMod(_)) | None => {}
 189                             Some(_) => {
 190                                 n = Some(TypeNS);
 191                                 duplicate_type = TypeError;
 192                             }
 193                         }
 194                         if child.value_ns.defined() {
 195                             duplicate_type = ValueError;
 196                             n = Some(ValueNS);
 197                         }
 198                         n
 199                     }
 200                     OverwriteDuplicates => None,
 201                 };
 202                 if duplicate_type != NoError {
 203                     // Return an error here by looking up the namespace that
 204                     // had the duplicate.
 205                     let ns = ns.unwrap();
 206                     resolve_error(
 207                         self,
 208                         sp,
 209                         ResolutionError::DuplicateDefinition(
 210                             namespace_error_to_string(duplicate_type),
 211                             name)
 212                     );
 213                     {
 214                         let r = child[ns].span();
 215                         if let Some(sp) = r {
 216                             self.session.span_note(sp,
 217                                                    &format!("first definition of {} `{}` here",
 218                                       namespace_error_to_string(duplicate_type),
 219                                       name));
 220                         }
 221                     }
 222                 }
 223                 child
 224             }
 225         }
 226     }
 227
 228     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 229         // Check each statement.
 230         for statement in &block.stmts {
 231             match statement.node {
 232                 StmtDecl(ref declaration, _) => {
 233                     match declaration.node {
 234                         DeclItem(_) => {
 235                             return true;
 236                         }
 237                         _ => {
 238                             // Keep searching.
 239                         }
 240                     }
 241                 }
 242                 _ => {
 243                     // Keep searching.
 244                 }
 245             }
 246         }
 247
 248         // If we found no items, we don't need to create
 249         // an anonymous module.
 250
 251         return false;
 252     }
 253
 254     fn get_parent_link(&mut self, parent: &Rc<Module>, name: Name) -> ParentLink {
 255         ModuleParentLink(Rc::downgrade(parent), name)
 256     }
 257
 258     /// Constructs the reduced graph for one item.
 259     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: &Rc<Module>) -> Rc<Module> {
 260         let name = item.name;
 261         let sp = item.span;
 262         let is_public = item.vis == hir::Public;
 263         let modifiers = if is_public {
 264             DefModifiers::PUBLIC
 265         } else {
 266             DefModifiers::empty()
 267         } | DefModifiers::IMPORTABLE;
 268
 269         match item.node {
 270             ItemUse(ref view_path) => {
 271                 // Extract and intern the module part of the path. For
 272                 // globs and lists, the path is found directly in the AST;
 273                 // for simple paths we have to munge the path a little.
 274                 let module_path = match view_path.node {
 275                     ViewPathSimple(_, ref full_path) => {
 276                         full_path.segments
 277                                  .split_last()
 278                                  .unwrap()
 279                                  .1
 280                                  .iter()
 281                                  .map(|seg| seg.identifier.name)
 282                                  .collect()
 283                     }
 284
 285                     ViewPathGlob(ref module_ident_path) |
 286                     ViewPathList(ref module_ident_path, _) => {
 287                         module_ident_path.segments
 288                                          .iter()
 289                                          .map(|seg| seg.identifier.name)
 290                                          .collect()
 291                     }
 292                 };
 293
 294                 // Build up the import directives.
 295                 let shadowable = item.attrs.iter().any(|attr| {
 296                     attr.name() == special_idents::prelude_import.name.as_str()
 297                 });
 298                 let shadowable = if shadowable {
 299                     Shadowable::Always
 300                 } else {
 301                     Shadowable::Never
 302                 };
 303
 304                 match view_path.node {
 305                     ViewPathSimple(binding, ref full_path) => {
 306                         let source_name = full_path.segments.last().unwrap().identifier.name;
 307                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 308                             resolve_error(self,
 309                                           view_path.span,
 310                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 311                         }
 312
 313                         let subclass = SingleImport(binding, source_name);
 314                         self.build_import_directive(&**parent,
 315                                                     module_path,
 316                                                     subclass,
 317                                                     view_path.span,
 318                                                     item.id,
 319                                                     is_public,
 320                                                     shadowable);
 321                     }
 322                     ViewPathList(_, ref source_items) => {
 323                         // Make sure there's at most one `mod` import in the list.
 324                         let mod_spans = source_items.iter()
 325                                                     .filter_map(|item| {
 326                                                         match item.node {
 327                                                             PathListMod { .. } => Some(item.span),
 328                                                             _ => None,
 329                                                         }
 330                                                     })
 331                                                     .collect::<Vec<Span>>();
 332                         if mod_spans.len() > 1 {
 333                             resolve_error(self,
 334                                           mod_spans[0],
 335                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 336                             for other_span in mod_spans.iter().skip(1) {
 337                                 self.session
 338                                     .span_note(*other_span, "another `self` import appears here");
 339                             }
 340                         }
 341
 342                         for source_item in source_items {
 343                             let (module_path, name, rename) = match source_item.node {
 344                                 PathListIdent { name, rename, .. } =>
 345                                     (module_path.clone(), name, rename.unwrap_or(name)),
 346                                 PathListMod { rename, .. } => {
 347                                     let name = match module_path.last() {
 348                                         Some(name) => *name,
 349                                         None => {
 350                                             resolve_error(
 351                                                 self,
 352                                                 source_item.span,
 353                                                 ResolutionError::
 354                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 355                                             );
 356                                             continue;
 357                                         }
 358                                     };
 359                                     let module_path = module_path.split_last().unwrap().1;
 360                                     let rename = rename.unwrap_or(name);
 361                                     (module_path.to_vec(), name, rename)
 362                                 }
 363                             };
 364                             self.build_import_directive(&**parent,
 365                                                         module_path,
 366                                                         SingleImport(rename, name),
 367                                                         source_item.span,
 368                                                         source_item.node.id(),
 369                                                         is_public,
 370                                                         shadowable);
 371                         }
 372                     }
 373                     ViewPathGlob(_) => {
 374                         self.build_import_directive(&**parent,
 375                                                     module_path,
 376                                                     GlobImport,
 377                                                     view_path.span,
 378                                                     item.id,
 379                                                     is_public,
 380                                                     shadowable);
 381                     }
 382                 }
 383                 parent.clone()
 384             }
 385
 386             ItemExternCrate(_) => {
 387                 // n.b. we don't need to look at the path option here, because cstore already
 388                 // did
 389                 if let Some(crate_id) = self.session.cstore.find_extern_mod_stmt_cnum(item.id) {
 390                     let def_id = DefId {
 391                         krate: crate_id,
 392                         index: CRATE_DEF_INDEX,
 393                     };
 394                     self.external_exports.insert(def_id);
 395                     let parent_link = ModuleParentLink(Rc::downgrade(parent), name);
 396                     let external_module = Rc::new(Module::new(parent_link,
 397                                                               Some(DefMod(def_id)),
 398                                                               false,
 399                                                               true));
 400                     debug!("(build reduced graph for item) found extern `{}`",
 401                            module_to_string(&*external_module));
 402                     self.check_for_conflicts_between_external_crates(&**parent, name, sp);
 403                     parent.external_module_children
 404                           .borrow_mut()
 405                           .insert(name, external_module.clone());
 406                     self.build_reduced_graph_for_external_crate(&external_module);
 407                 }
 408                 parent.clone()
 409             }
 410
 411             ItemMod(..) => {
 412                 let child = parent.children.borrow().get(&name).cloned();
 413                 if let Some(child) = child {
 414                     // check if there's struct of the same name already defined
 415                     if child.type_ns.defined() &&
 416                        child.get_module_if_available().is_none() {
 417                         self.session.span_warn(sp,
 418                                                &format!("duplicate definition of {} `{}`. \
 419                                                          Defining a module and a struct with \
 420                                                          the same name will be disallowed soon.",
 421                                                         namespace_error_to_string(TypeError),
 422                                                         name));
 423                         {
 424                             let r = child.type_ns.span();
 425                             if let Some(sp) = r {
 426                                 self.session.span_note(sp,
 427                                                        &format!("first definition of {} `{}` here",
 428                                           namespace_error_to_string(TypeError),
 429                                           name));
 430                             }
 431                         }
 432                     }
 433                 }
 434                 let name_bindings = self.add_child(name, parent, ForbidDuplicateModules, sp);
 435
 436                 let parent_link = self.get_parent_link(parent, name);
 437                 let def = DefMod(self.ast_map.local_def_id(item.id));
 438                 name_bindings.define_module(parent_link, Some(def), false, is_public, sp);
 439
 440                 name_bindings.get_module()
 441             }
 442
 443             ItemForeignMod(..) => parent.clone(),
 444
 445             // These items live in the value namespace.
 446             ItemStatic(_, m, _) => {
 447                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 448                 let mutbl = m == hir::MutMutable;
 449
 450                 name_bindings.define_value(DefStatic(self.ast_map.local_def_id(item.id), mutbl),
 451                                            sp,
 452                                            modifiers);
 453                 parent.clone()
 454             }
 455             ItemConst(_, _) => {
 456                 self.add_child(name, parent, ForbidDuplicateValues, sp)
 457                     .define_value(DefConst(self.ast_map.local_def_id(item.id)), sp, modifiers);
 458                 parent.clone()
 459             }
 460             ItemFn(_, _, _, _, _, _) => {
 461                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 462
 463                 let def = DefFn(self.ast_map.local_def_id(item.id), false);
 464                 name_bindings.define_value(def, sp, modifiers);
 465                 parent.clone()
 466             }
 467
 468             // These items live in the type namespace.
 469             ItemTy(..) => {
 470                 let name_bindings = self.add_child(name,
 471                                                    parent,
 472                                                    ForbidDuplicateTypesAndModules,
 473                                                    sp);
 474
 475                 let parent_link = self.get_parent_link(parent, name);
 476                 let def = DefTy(self.ast_map.local_def_id(item.id), false);
 477                 name_bindings.define_module(parent_link, Some(def), false, is_public, sp);
 478                 parent.clone()
 479             }
 480
 481             ItemEnum(ref enum_definition, _) => {
 482                 let name_bindings = self.add_child(name,
 483                                                    parent,
 484                                                    ForbidDuplicateTypesAndModules,
 485                                                    sp);
 486
 487                 let parent_link = self.get_parent_link(parent, name);
 488                 let def = DefTy(self.ast_map.local_def_id(item.id), true);
 489                 name_bindings.define_module(parent_link, Some(def), false, is_public, sp);
 490
 491                 let module = name_bindings.get_module();
 492
 493                 for variant in &(*enum_definition).variants {
 494                     let item_def_id = self.ast_map.local_def_id(item.id);
 495                     self.build_reduced_graph_for_variant(&**variant, item_def_id, &module);
 496                 }
 497                 parent.clone()
 498             }
 499
 500             // These items live in both the type and value namespaces.
 501             ItemStruct(ref struct_def, _) => {
 502                 // Adding to both Type and Value namespaces or just Type?
 503                 let (forbid, ctor_id) = if struct_def.is_struct() {
 504                     (ForbidDuplicateTypesAndModules, None)
 505                 } else {
 506                     let child = parent.children.borrow().get(&name).cloned();
 507                     if let Some(child) = child {
 508                         // check if theres a DefMod
 509                         if let Some(DefMod(_)) = child.type_ns.def() {
 510                             self.session.span_warn(sp,
 511                                                    &format!("duplicate definition of {} `{}`. \
 512                                                              Defining a module and a struct \
 513                                                              with the same name will be \
 514                                                              disallowed soon.",
 515                                                             namespace_error_to_string(TypeError),
 516                                                             name));
 517                             {
 518                                 let r = child.type_ns.span();
 519                                 if let Some(sp) = r {
 520                                     self.session
 521                                         .span_note(sp,
 522                                                    &format!("first definition of {} `{}` here",
 523                                                             namespace_error_to_string(TypeError),
 524                                                             name));
 525                                 }
 526                             }
 527                         }
 528                     }
 529                     (ForbidDuplicateTypesAndValues, Some(struct_def.id()))
 530                 };
 531
 532                 let name_bindings = self.add_child(name, parent, forbid, sp);
 533
 534                 // Define a name in the type namespace.
 535                 name_bindings.define_type(DefTy(self.ast_map.local_def_id(item.id), false),
 536                                           sp,
 537                                           modifiers);
 538
 539                 // If this is a newtype or unit-like struct, define a name
 540                 // in the value namespace as well
 541                 if let Some(cid) = ctor_id {
 542                     name_bindings.define_value(DefStruct(self.ast_map.local_def_id(cid)),
 543                                                sp,
 544                                                modifiers);
 545                 }
 546
 547                 // Record the def ID and fields of this struct.
 548                 let named_fields = struct_def.fields()
 549                                              .iter()
 550                                              .filter_map(|f| {
 551                                                  match f.node.kind {
 552                                                      NamedField(name, _) => Some(name),
 553                                                      UnnamedField(_) => None,
 554                                                  }
 555                                              })
 556                                              .collect();
 557                 let item_def_id = self.ast_map.local_def_id(item.id);
 558                 self.structs.insert(item_def_id, named_fields);
 559
 560                 parent.clone()
 561             }
 562
 563             ItemDefaultImpl(_, _) |
 564             ItemImpl(..) => parent.clone(),
 565
 566             ItemTrait(_, _, _, ref items) => {
 567                 let name_bindings = self.add_child(name,
 568                                                    parent,
 569                                                    ForbidDuplicateTypesAndModules,
 570                                                    sp);
 571
 572                 let def_id = self.ast_map.local_def_id(item.id);
 573
 574                 // Add all the items within to a new module.
 575                 let parent_link = self.get_parent_link(parent, name);
 576                 let def = DefTrait(def_id);
 577                 name_bindings.define_module(parent_link, Some(def), false, is_public, sp);
 578                 let module_parent = name_bindings.get_module();
 579
 580                 // Add the names of all the items to the trait info.
 581                 for trait_item in items {
 582                     let name_bindings = self.add_child(trait_item.name,
 583                                                        &module_parent,
 584                                                        ForbidDuplicateTypesAndValues,
 585                                                        trait_item.span);
 586
 587                     match trait_item.node {
 588                         hir::ConstTraitItem(..) => {
 589                             let def = DefAssociatedConst(self.ast_map.local_def_id(trait_item.id));
 590                             // NB: not DefModifiers::IMPORTABLE
 591                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 592                         }
 593                         hir::MethodTraitItem(..) => {
 594                             let def = DefMethod(self.ast_map.local_def_id(trait_item.id));
 595                             // NB: not DefModifiers::IMPORTABLE
 596                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 597                         }
 598                         hir::TypeTraitItem(..) => {
 599                             let def = DefAssociatedTy(self.ast_map.local_def_id(item.id),
 600                                                       self.ast_map.local_def_id(trait_item.id));
 601                             // NB: not DefModifiers::IMPORTABLE
 602                             name_bindings.define_type(def, trait_item.span, DefModifiers::PUBLIC);
 603                         }
 604                     }
 605
 606                     let trait_item_def_id = self.ast_map.local_def_id(trait_item.id);
 607                     self.trait_item_map.insert((trait_item.name, def_id), trait_item_def_id);
 608                 }
 609
 610                 parent.clone()
 611             }
 612         }
 613     }
 614
 615     // Constructs the reduced graph for one variant. Variants exist in the
 616     // type and value namespaces.
 617     fn build_reduced_graph_for_variant(&mut self,
 618                                        variant: &Variant,
 619                                        item_id: DefId,
 620                                        parent: &Rc<Module>) {
 621         let name = variant.node.name;
 622         let is_exported = if variant.node.data.is_struct() {
 623             // Not adding fields for variants as they are not accessed with a self receiver
 624             let variant_def_id = self.ast_map.local_def_id(variant.node.data.id());
 625             self.structs.insert(variant_def_id, Vec::new());
 626             true
 627         } else {
 628             false
 629         };
 630
 631         let child = self.add_child(name, parent, ForbidDuplicateTypesAndValues, variant.span);
 632         // variants are always treated as importable to allow them to be glob
 633         // used
 634         child.define_value(DefVariant(item_id,
 635                                       self.ast_map.local_def_id(variant.node.data.id()),
 636                                       is_exported),
 637                            variant.span,
 638                            DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 639         child.define_type(DefVariant(item_id,
 640                                      self.ast_map.local_def_id(variant.node.data.id()),
 641                                      is_exported),
 642                           variant.span,
 643                           DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 644     }
 645
 646     /// Constructs the reduced graph for one foreign item.
 647     fn build_reduced_graph_for_foreign_item(&mut self,
 648                                             foreign_item: &ForeignItem,
 649                                             parent: &Rc<Module>) {
 650         let name = foreign_item.name;
 651         let is_public = foreign_item.vis == hir::Public;
 652         let modifiers = if is_public {
 653             DefModifiers::PUBLIC
 654         } else {
 655             DefModifiers::empty()
 656         } | DefModifiers::IMPORTABLE;
 657         let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, foreign_item.span);
 658
 659         let def = match foreign_item.node {
 660             ForeignItemFn(..) => {
 661                 DefFn(self.ast_map.local_def_id(foreign_item.id), false)
 662             }
 663             ForeignItemStatic(_, m) => {
 664                 DefStatic(self.ast_map.local_def_id(foreign_item.id), m)
 665             }
 666         };
 667         name_bindings.define_value(def, foreign_item.span, modifiers);
 668     }
 669
 670     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &Rc<Module>) -> Rc<Module> {
 671         if self.block_needs_anonymous_module(block) {
 672             let block_id = block.id;
 673
 674             debug!("(building reduced graph for block) creating a new anonymous module for block \
 675                     {}",
 676                    block_id);
 677
 678             let new_module = Rc::new(Module::new(BlockParentLink(Rc::downgrade(parent), block_id),
 679                                                  None,
 680                                                  false,
 681                                                  false));
 682             parent.anonymous_children.borrow_mut().insert(block_id, new_module.clone());
 683             new_module
 684         } else {
 685             parent.clone()
 686         }
 687     }
 688
 689     fn handle_external_def(&mut self,
 690                            def: Def,
 691                            vis: Visibility,
 692                            child_name_bindings: &NameBindings,
 693                            final_ident: &str,
 694                            name: Name,
 695                            new_parent: &Rc<Module>) {
 696         debug!("(building reduced graph for external crate) building external def {}, priv {:?}",
 697                final_ident,
 698                vis);
 699         let is_public = vis == hir::Public;
 700         let modifiers = if is_public {
 701             DefModifiers::PUBLIC
 702         } else {
 703             DefModifiers::empty()
 704         } | DefModifiers::IMPORTABLE;
 705         let is_exported = is_public &&
 706                           match new_parent.def_id() {
 707             None => true,
 708             Some(did) => self.external_exports.contains(&did),
 709         };
 710         if is_exported {
 711             self.external_exports.insert(def.def_id());
 712         }
 713
 714         match def {
 715             DefMod(_) |
 716             DefForeignMod(_) |
 717             DefStruct(_) |
 718             DefTy(..) => {
 719                 if let Some(module_def) = child_name_bindings.type_ns.module() {
 720                     debug!("(building reduced graph for external crate) already created module");
 721                     module_def.def.set(Some(def));
 722                 } else {
 723                     debug!("(building reduced graph for external crate) building module {} {}",
 724                            final_ident,
 725                            is_public);
 726                     let parent_link = self.get_parent_link(new_parent, name);
 727
 728                     child_name_bindings.define_module(parent_link,
 729                                                       Some(def),
 730                                                       true,
 731                                                       is_public,
 732                                                       DUMMY_SP);
 733                 }
 734             }
 735             _ => {}
 736         }
 737
 738         match def {
 739             DefMod(_) | DefForeignMod(_) => {}
 740             DefVariant(_, variant_id, is_struct) => {
 741                 debug!("(building reduced graph for external crate) building variant {}",
 742                        final_ident);
 743                 // variants are always treated as importable to allow them to be
 744                 // glob used
 745                 let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 746                 if is_struct {
 747                     child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 748                     // Not adding fields for variants as they are not accessed with a self receiver
 749                     self.structs.insert(variant_id, Vec::new());
 750                 } else {
 751                     child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 752                 }
 753             }
 754             DefFn(ctor_id, true) => {
 755                 child_name_bindings.define_value(
 756                 csearch::get_tuple_struct_definition_if_ctor(&self.session.cstore, ctor_id)
 757                     .map_or(def, |_| DefStruct(ctor_id)), DUMMY_SP, modifiers);
 758             }
 759             DefFn(..) |
 760             DefStatic(..) |
 761             DefConst(..) |
 762             DefAssociatedConst(..) |
 763             DefMethod(..) => {
 764                 debug!("(building reduced graph for external crate) building value (fn/static) {}",
 765                        final_ident);
 766                 // impl methods have already been defined with the correct importability
 767                 // modifier
 768                 let mut modifiers = match *child_name_bindings.value_ns.borrow() {
 769                     Some(ref def) => (modifiers & !DefModifiers::IMPORTABLE) |
 770                                      (def.modifiers & DefModifiers::IMPORTABLE),
 771                     None => modifiers,
 772                 };
 773                 if !new_parent.is_normal() {
 774                     modifiers = modifiers & !DefModifiers::IMPORTABLE;
 775                 }
 776                 child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 777             }
 778             DefTrait(def_id) => {
 779                 debug!("(building reduced graph for external crate) building type {}",
 780                        final_ident);
 781
 782                 // If this is a trait, add all the trait item names to the trait
 783                 // info.
 784
 785                 let trait_item_def_ids = csearch::get_trait_item_def_ids(&self.session.cstore,
 786                                                                          def_id);
 787                 for trait_item_def in &trait_item_def_ids {
 788                     let trait_item_name = csearch::get_trait_name(&self.session.cstore,
 789                                                                   trait_item_def.def_id());
 790
 791                     debug!("(building reduced graph for external crate) ... adding trait item \
 792                             '{}'",
 793                            trait_item_name);
 794
 795                     self.trait_item_map.insert((trait_item_name, def_id), trait_item_def.def_id());
 796
 797                     if is_exported {
 798                         self.external_exports.insert(trait_item_def.def_id());
 799                     }
 800                 }
 801
 802                 // Define a module if necessary.
 803                 let parent_link = self.get_parent_link(new_parent, name);
 804                 child_name_bindings.define_module(parent_link,
 805                                                   Some(def),
 806                                                   true,
 807                                                   is_public,
 808                                                   DUMMY_SP)
 809             }
 810             DefTy(..) | DefAssociatedTy(..) => {
 811                 debug!("(building reduced graph for external crate) building type {}",
 812                        final_ident);
 813
 814                 let modifiers = match new_parent.is_normal() {
 815                     true => modifiers,
 816                     _ => modifiers & !DefModifiers::IMPORTABLE,
 817                 };
 818
 819                 if let DefTy(..) = def {
 820                     child_name_bindings.type_ns.set_modifiers(modifiers);
 821                 } else {
 822                     child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 823                 }
 824             }
 825             DefStruct(def_id) => {
 826                 debug!("(building reduced graph for external crate) building type and value for \
 827                         {}",
 828                        final_ident);
 829                 let fields = csearch::get_struct_field_names(&self.session.cstore, def_id);
 830
 831                 if fields.is_empty() {
 832                     child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 833                 }
 834
 835                 // Record the def ID and fields of this struct.
 836                 self.structs.insert(def_id, fields);
 837             }
 838             DefLocal(..) |
 839             DefPrimTy(..) |
 840             DefTyParam(..) |
 841             DefUse(..) |
 842             DefUpvar(..) |
 843             DefLabel(..) |
 844             DefSelfTy(..) => {
 845                 panic!("didn't expect `{:?}`", def);
 846             }
 847         }
 848     }
 849
 850     /// Builds the reduced graph for a single item in an external crate.
 851     fn build_reduced_graph_for_external_crate_def(&mut self,
 852                                                   root: &Rc<Module>,
 853                                                   def_like: DefLike,
 854                                                   name: Name,
 855                                                   def_visibility: Visibility) {
 856         match def_like {
 857             DlDef(def) => {
 858                 // Add the new child item, if necessary.
 859                 match def {
 860                     DefForeignMod(def_id) => {
 861                         // Foreign modules have no names. Recur and populate
 862                         // eagerly.
 863                         csearch::each_child_of_item(&self.session.cstore,
 864                                                     def_id,
 865                                                     |def_like,
 866                                                      child_name,
 867                                                      vis| {
 868                             self.build_reduced_graph_for_external_crate_def(
 869                                 root,
 870                                 def_like,
 871                                 child_name,
 872                                 vis)
 873                         });
 874                     }
 875                     _ => {
 876                         let child_name_bindings = self.add_child(name,
 877                                                                  root,
 878                                                                  OverwriteDuplicates,
 879                                                                  DUMMY_SP);
 880
 881                         self.handle_external_def(def,
 882                                                  def_visibility,
 883                                                  &child_name_bindings,
 884                                                  &name.as_str(),
 885                                                  name,
 886                                                  root);
 887                     }
 888                 }
 889             }
 890             DlImpl(_) => {
 891                 debug!("(building reduced graph for external crate) ignoring impl");
 892             }
 893             DlField => {
 894                 debug!("(building reduced graph for external crate) ignoring field");
 895             }
 896         }
 897     }
 898
 899     /// Builds the reduced graph rooted at the given external module.
 900     fn populate_external_module(&mut self, module: &Rc<Module>) {
 901         debug!("(populating external module) attempting to populate {}",
 902                module_to_string(&**module));
 903
 904         let def_id = match module.def_id() {
 905             None => {
 906                 debug!("(populating external module) ... no def ID!");
 907                 return;
 908             }
 909             Some(def_id) => def_id,
 910         };
 911
 912         csearch::each_child_of_item(&self.session.cstore,
 913                                     def_id,
 914                                     |def_like, child_name, visibility| {
 915                                         debug!("(populating external module) ... found ident: {}",
 916                                                child_name);
 917                                         self.build_reduced_graph_for_external_crate_def(module,
 918                                                                                         def_like,
 919                                                                                         child_name,
 920                                                                                         visibility)
 921                                     });
 922         module.populated.set(true)
 923     }
 924
 925     /// Ensures that the reduced graph rooted at the given external module
 926     /// is built, building it if it is not.
 927     fn populate_module_if_necessary(&mut self, module: &Rc<Module>) {
 928         if !module.populated.get() {
 929             self.populate_external_module(module)
 930         }
 931         assert!(module.populated.get())
 932     }
 933
 934     /// Builds the reduced graph rooted at the 'use' directive for an external
 935     /// crate.
 936     fn build_reduced_graph_for_external_crate(&mut self, root: &Rc<Module>) {
 937         csearch::each_top_level_item_of_crate(&self.session.cstore,
 938                                               root.def_id()
 939                                                   .unwrap()
 940                                                   .krate,
 941                                               |def_like, name, visibility| {
 942             self.build_reduced_graph_for_external_crate_def(root, def_like, name, visibility)
 943         });
 944     }
 945
 946     /// Creates and adds an import directive to the given module.
 947     fn build_import_directive(&mut self,
 948                               module_: &Module,
 949                               module_path: Vec<Name>,
 950                               subclass: ImportDirectiveSubclass,
 951                               span: Span,
 952                               id: NodeId,
 953                               is_public: bool,
 954                               shadowable: Shadowable) {
 955         module_.imports
 956                .borrow_mut()
 957                .push(ImportDirective::new(module_path, subclass, span, id, is_public, shadowable));
 958         self.unresolved_imports += 1;
 959
 960         if is_public {
 961             module_.inc_pub_count();
 962         }
 963
 964         // Bump the reference count on the name. Or, if this is a glob, set
 965         // the appropriate flag.
 966
 967         match subclass {
 968             SingleImport(target, _) => {
 969                 debug!("(building import directive) building import directive: {}::{}",
 970                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 971                        target);
 972
 973                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 974                 match import_resolutions.get_mut(&target) {
 975                     Some(resolution) => {
 976                         debug!("(building import directive) bumping reference");
 977                         resolution.outstanding_references += 1;
 978
 979                         // the source of this name is different now
 980                         resolution.type_id = id;
 981                         resolution.value_id = id;
 982                         resolution.is_public = is_public;
 983                         return;
 984                     }
 985                     None => {}
 986                 }
 987                 debug!("(building import directive) creating new");
 988                 let mut resolution = ImportResolution::new(id, is_public);
 989                 resolution.outstanding_references = 1;
 990                 import_resolutions.insert(target, resolution);
 991             }
 992             GlobImport => {
 993                 // Set the glob flag. This tells us that we don't know the
 994                 // module's exports ahead of time.
 995
 996                 module_.inc_glob_count();
 997                 if is_public {
 998                     module_.inc_pub_glob_count();
 999                 }
1000             }
1001         }
1002     }
1003 }
1004
1005 struct BuildReducedGraphVisitor<'a, 'b: 'a, 'tcx: 'b> {
1006     builder: GraphBuilder<'a, 'b, 'tcx>,
1007     parent: Rc<Module>,
1008 }
1009
1010 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
1011     fn visit_item(&mut self, item: &Item) {
1012         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
1013         let old_parent = replace(&mut self.parent, p);
1014         visit::walk_item(self, item);
1015         self.parent = old_parent;
1016     }
1017
1018     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
1019         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
1020     }
1021
1022     fn visit_block(&mut self, block: &Block) {
1023         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
1024         let old_parent = replace(&mut self.parent, np);
1025         visit::walk_block(self, block);
1026         self.parent = old_parent;
1027     }
1028 }
1029
1030 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &hir::Crate) {
1031     GraphBuilder { resolver: resolver }.build_reduced_graph(krate);
1032 }
1033
1034 pub fn populate_module_if_necessary(resolver: &mut Resolver, module: &Rc<Module>) {
1035     GraphBuilder { resolver: resolver }.populate_module_if_necessary(module);
1036 }