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 macros::{InvocationData, LegacyScope};
  17 use resolve_imports::ImportDirective;
  18 use resolve_imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
  19 use {Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, ToNameBinding};
  20 use {PerNS, Resolver, ResolverArenas};
  21 use Namespace::{self, TypeNS, ValueNS, MacroNS};
  22 use {resolve_error, resolve_struct_error, ResolutionError};
  23
  24 use rustc::middle::cstore::LoadedMacro;
  25 use rustc::hir::def::*;
  26 use rustc::hir::def_id::{BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  27 use rustc::ty;
  28
  29 use std::cell::Cell;
  30 use rustc_data_structures::sync::Lrc;
  31
  32 use syntax::ast::{Name, Ident};
  33 use syntax::attr;
  34
  35 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  36 use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  37 use syntax::ext::base::SyntaxExtension;
  38 use syntax::ext::base::Determinacy::Undetermined;
  39 use syntax::ext::hygiene::Mark;
  40 use syntax::ext::tt::macro_rules;
  41 use syntax::parse::token::{self, Token};
  42 use syntax::std_inject::injected_crate_name;
  43 use syntax::symbol::keywords;
  44 use syntax::visit::{self, Visitor};
  45
  46 use syntax_pos::{Span, DUMMY_SP};
  47
  48 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  49     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  50         arenas.alloc_name_binding(NameBinding {
  51             kind: NameBindingKind::Module(self.0),
  52             vis: self.1,
  53             span: self.2,
  54             expansion: self.3,
  55         })
  56     }
  57 }
  58
  59 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  60     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  61         arenas.alloc_name_binding(NameBinding {
  62             kind: NameBindingKind::Def(self.0),
  63             vis: self.1,
  64             span: self.2,
  65             expansion: self.3,
  66         })
  67     }
  68 }
  69
  70 #[derive(Default, PartialEq, Eq)]
  71 struct LegacyMacroImports {
  72     import_all: Option<Span>,
  73     imports: Vec<(Name, Span)>,
  74 }
  75
  76 impl<'a> Resolver<'a> {
  77     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  78     /// otherwise, reports an error.
  79     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  80         where T: ToNameBinding<'a>,
  81     {
  82         let binding = def.to_name_binding(self.arenas);
  83         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  84             self.report_conflict(parent, ident, ns, old_binding, &binding);
  85         }
  86     }
  87
  88     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  89         // If any statements are items, we need to create an anonymous module
  90         block.stmts.iter().any(|statement| match statement.node {
  91             StmtKind::Item(_) | StmtKind::Mac(_) => true,
  92             _ => false,
  93         })
  94     }
  95
  96     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
  97         if !field_names.is_empty() {
  98             self.field_names.insert(def_id, field_names);
  99         }
 100     }
 101
 102     fn build_reduced_graph_for_use_tree(&mut self,
 103                                         root_use_tree: &ast::UseTree,
 104                                         root_id: NodeId,
 105                                         use_tree: &ast::UseTree,
 106                                         id: NodeId,
 107                                         vis: ty::Visibility,
 108                                         prefix: &ast::Path,
 109                                         nested: bool,
 110                                         item: &Item,
 111                                         expansion: Mark) {
 112         let is_prelude = attr::contains_name(&item.attrs, "prelude_import");
 113         let path = &use_tree.prefix;
 114
 115         let mut module_path: Vec<_> = prefix.segments.iter()
 116             .chain(path.segments.iter())
 117             .map(|seg| seg.ident)
 118             .collect();
 119
 120         match use_tree.kind {
 121             ast::UseTreeKind::Simple(rename, ..) => {
 122                 let mut ident = use_tree.ident();
 123                 let mut source = module_path.pop().unwrap();
 124                 let mut type_ns_only = false;
 125
 126                 if nested {
 127                     // Correctly handle `self`
 128                     if source.name == keywords::SelfValue.name() {
 129                         type_ns_only = true;
 130
 131                         let last_segment = *module_path.last().unwrap();
 132                         if last_segment.name == keywords::CrateRoot.name() {
 133                             resolve_error(
 134                                 self,
 135                                 use_tree.span,
 136                                 ResolutionError::
 137                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 138                             );
 139                             return;
 140                         }
 141
 142                         // Replace `use foo::self;` with `use foo;`
 143                         let _ = module_path.pop();
 144                         source = last_segment;
 145                         if rename.is_none() {
 146                             ident = last_segment;
 147                         }
 148                     }
 149                 } else {
 150                     // Disallow `self`
 151                     if source.name == keywords::SelfValue.name() {
 152                         resolve_error(self,
 153                                       use_tree.span,
 154                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 155                     }
 156
 157                     // Disallow `use $crate;`
 158                     if source.name == keywords::DollarCrate.name() && path.segments.len() == 1 {
 159                         let crate_root = self.resolve_crate_root(source);
 160                         let crate_name = match crate_root.kind {
 161                             ModuleKind::Def(_, name) => name,
 162                             ModuleKind::Block(..) => unreachable!(),
 163                         };
 164                         source.name = crate_name;
 165                         if rename.is_none() {
 166                             ident.name = crate_name;
 167                         }
 168
 169                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 170                             .note("`use $crate;` was erroneously allowed and \
 171                                    will become a hard error in a future release")
 172                             .emit();
 173                     }
 174                 }
 175
 176                 let subclass = SingleImport {
 177                     target: ident,
 178                     source,
 179                     result: PerNS {
 180                         type_ns: Cell::new(Err(Undetermined)),
 181                         value_ns: Cell::new(Err(Undetermined)),
 182                         macro_ns: Cell::new(Err(Undetermined)),
 183                     },
 184                     type_ns_only,
 185                 };
 186                 self.add_import_directive(
 187                     module_path,
 188                     subclass,
 189                     use_tree.span,
 190                     id,
 191                     root_use_tree.span,
 192                     root_id,
 193                     vis,
 194                     expansion,
 195                 );
 196             }
 197             ast::UseTreeKind::Glob => {
 198                 let subclass = GlobImport {
 199                     is_prelude,
 200                     max_vis: Cell::new(ty::Visibility::Invisible),
 201                 };
 202                 self.add_import_directive(
 203                     module_path,
 204                     subclass,
 205                     use_tree.span,
 206                     id,
 207                     root_use_tree.span,
 208                     root_id,
 209                     vis,
 210                     expansion,
 211                 );
 212             }
 213             ast::UseTreeKind::Nested(ref items) => {
 214                 let prefix = ast::Path {
 215                     segments: module_path.into_iter()
 216                         .map(|ident| ast::PathSegment::from_ident(ident))
 217                         .collect(),
 218                     span: path.span,
 219                 };
 220
 221                 // Ensure there is at most one `self` in the list
 222                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 223                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 224                         if use_tree.ident().name == keywords::SelfValue.name() {
 225                             return Some(use_tree.span);
 226                         }
 227                     }
 228
 229                     None
 230                 }).collect::<Vec<_>>();
 231                 if self_spans.len() > 1 {
 232                     let mut e = resolve_struct_error(self,
 233                         self_spans[0],
 234                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 235
 236                     for other_span in self_spans.iter().skip(1) {
 237                         e.span_label(*other_span, "another `self` import appears here");
 238                     }
 239
 240                     e.emit();
 241                 }
 242
 243                 for &(ref tree, id) in items {
 244                     self.build_reduced_graph_for_use_tree(
 245                         root_use_tree, root_id, tree, id, vis, &prefix, true, item, expansion
 246                     );
 247                 }
 248             }
 249         }
 250     }
 251
 252     /// Constructs the reduced graph for one item.
 253     fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
 254         let parent = self.current_module;
 255         let ident = item.ident;
 256         let sp = item.span;
 257         let vis = self.resolve_visibility(&item.vis);
 258
 259         match item.node {
 260             ItemKind::Use(ref use_tree) => {
 261                 // Imports are resolved as global by default, add starting root segment.
 262                 let prefix = ast::Path {
 263                     segments: use_tree.prefix.make_root().into_iter().collect(),
 264                     span: use_tree.span,
 265                 };
 266
 267                 self.build_reduced_graph_for_use_tree(
 268                     use_tree, item.id, use_tree, item.id, vis, &prefix, false, item, expansion,
 269                 );
 270             }
 271
 272             ItemKind::ExternCrate(orig_name) => {
 273                 let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 274                 let module =
 275                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 276                 self.populate_module_if_necessary(module);
 277                 if injected_crate_name().map_or(false, |name| item.ident.name == name) {
 278                     self.injected_crate = Some(module);
 279                 }
 280
 281                 let used = self.process_legacy_macro_imports(item, module, expansion);
 282                 let binding =
 283                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 284                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 285                     root_id: item.id,
 286                     id: item.id,
 287                     parent,
 288                     imported_module: Cell::new(Some(module)),
 289                     subclass: ImportDirectiveSubclass::ExternCrate(orig_name),
 290                     root_span: item.span,
 291                     span: item.span,
 292                     module_path: Vec::new(),
 293                     vis: Cell::new(vis),
 294                     expansion,
 295                     used: Cell::new(used),
 296                 });
 297                 self.potentially_unused_imports.push(directive);
 298                 let imported_binding = self.import(binding, directive);
 299                 self.define(parent, ident, TypeNS, imported_binding);
 300             }
 301
 302             ItemKind::GlobalAsm(..) => {}
 303
 304             ItemKind::Mod(..) if item.ident == keywords::Invalid.ident() => {} // Crate root
 305
 306             ItemKind::Mod(..) => {
 307                 let def_id = self.definitions.local_def_id(item.id);
 308                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 309                 let module = self.arenas.alloc_module(ModuleData {
 310                     no_implicit_prelude: parent.no_implicit_prelude || {
 311                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 312                     },
 313                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 314                 });
 315                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 316                 self.module_map.insert(def_id, module);
 317
 318                 // Descend into the module.
 319                 self.current_module = module;
 320             }
 321
 322             // Handled in `rustc_metadata::{native_libs,link_args}`
 323             ItemKind::ForeignMod(..) => {}
 324
 325             // These items live in the value namespace.
 326             ItemKind::Static(_, m, _) => {
 327                 let mutbl = m == Mutability::Mutable;
 328                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 329                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 330             }
 331             ItemKind::Const(..) => {
 332                 let def = Def::Const(self.definitions.local_def_id(item.id));
 333                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 334             }
 335             ItemKind::Fn(..) => {
 336                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 337                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 338             }
 339
 340             // These items live in the type namespace.
 341             ItemKind::Ty(..) => {
 342                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 343                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 344             }
 345
 346             ItemKind::Enum(ref enum_definition, _) => {
 347                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 348                 let module_kind = ModuleKind::Def(def, ident.name);
 349                 let module = self.new_module(parent,
 350                                              module_kind,
 351                                              parent.normal_ancestor_id,
 352                                              expansion,
 353                                              item.span);
 354                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 355
 356                 for variant in &(*enum_definition).variants {
 357                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 358                 }
 359             }
 360
 361             ItemKind::TraitAlias(..) => {
 362                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 363                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 364             }
 365
 366             // These items live in both the type and value namespaces.
 367             ItemKind::Struct(ref struct_def, _) => {
 368                 // Define a name in the type namespace.
 369                 let def_id = self.definitions.local_def_id(item.id);
 370                 let def = Def::Struct(def_id);
 371                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 372
 373                 let mut ctor_vis = vis;
 374
 375                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 376
 377                 // If the structure is marked as non_exhaustive then lower the visibility
 378                 // to within the crate.
 379                 if has_non_exhaustive && vis == ty::Visibility::Public {
 380                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 381                 }
 382
 383                 // Record field names for error reporting.
 384                 let field_names = struct_def.fields().iter().filter_map(|field| {
 385                     let field_vis = self.resolve_visibility(&field.vis);
 386                     if ctor_vis.is_at_least(field_vis, &*self) {
 387                         ctor_vis = field_vis;
 388                     }
 389                     field.ident.map(|ident| ident.name)
 390                 }).collect();
 391                 let item_def_id = self.definitions.local_def_id(item.id);
 392                 self.insert_field_names(item_def_id, field_names);
 393
 394                 // If this is a tuple or unit struct, define a name
 395                 // in the value namespace as well.
 396                 if !struct_def.is_struct() {
 397                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 398                                                    CtorKind::from_ast(struct_def));
 399                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 400                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 401                 }
 402             }
 403
 404             ItemKind::Union(ref vdata, _) => {
 405                 let def = Def::Union(self.definitions.local_def_id(item.id));
 406                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 407
 408                 // Record field names for error reporting.
 409                 let field_names = vdata.fields().iter().filter_map(|field| {
 410                     self.resolve_visibility(&field.vis);
 411                     field.ident.map(|ident| ident.name)
 412                 }).collect();
 413                 let item_def_id = self.definitions.local_def_id(item.id);
 414                 self.insert_field_names(item_def_id, field_names);
 415             }
 416
 417             ItemKind::Impl(..) => {}
 418
 419             ItemKind::Trait(..) => {
 420                 let def_id = self.definitions.local_def_id(item.id);
 421
 422                 // Add all the items within to a new module.
 423                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 424                 let module = self.new_module(parent,
 425                                              module_kind,
 426                                              parent.normal_ancestor_id,
 427                                              expansion,
 428                                              item.span);
 429                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 430                 self.current_module = module;
 431             }
 432
 433             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 434         }
 435     }
 436
 437     // Constructs the reduced graph for one variant. Variants exist in the
 438     // type and value namespaces.
 439     fn build_reduced_graph_for_variant(&mut self,
 440                                        variant: &Variant,
 441                                        parent: Module<'a>,
 442                                        vis: ty::Visibility,
 443                                        expansion: Mark) {
 444         let ident = variant.node.ident;
 445         let def_id = self.definitions.local_def_id(variant.node.data.id());
 446
 447         // Define a name in the type namespace.
 448         let def = Def::Variant(def_id);
 449         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 450
 451         // Define a constructor name in the value namespace.
 452         // Braced variants, unlike structs, generate unusable names in
 453         // value namespace, they are reserved for possible future use.
 454         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 455         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 456
 457         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 458     }
 459
 460     /// Constructs the reduced graph for one foreign item.
 461     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 462         let (def, ns) = match item.node {
 463             ForeignItemKind::Fn(..) => {
 464                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 465             }
 466             ForeignItemKind::Static(_, m) => {
 467                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 468             }
 469             ForeignItemKind::Ty => {
 470                 (Def::TyForeign(self.definitions.local_def_id(item.id)), TypeNS)
 471             }
 472             ForeignItemKind::Macro(_) => unreachable!(),
 473         };
 474         let parent = self.current_module;
 475         let vis = self.resolve_visibility(&item.vis);
 476         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 477     }
 478
 479     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 480         let parent = self.current_module;
 481         if self.block_needs_anonymous_module(block) {
 482             let module = self.new_module(parent,
 483                                          ModuleKind::Block(block.id),
 484                                          parent.normal_ancestor_id,
 485                                          expansion,
 486                                          block.span);
 487             self.block_map.insert(block.id, module);
 488             self.current_module = module; // Descend into the block.
 489         }
 490     }
 491
 492     /// Builds the reduced graph for a single item in an external crate.
 493     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 494         let Export { ident, def, vis, span, .. } = child;
 495         let def_id = def.def_id();
 496         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 497         match def {
 498             Def::Mod(..) | Def::Enum(..) => {
 499                 let module = self.new_module(parent,
 500                                              ModuleKind::Def(def, ident.name),
 501                                              def_id,
 502                                              expansion,
 503                                              span);
 504                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 505             }
 506             Def::Variant(..) | Def::TyAlias(..) | Def::TyForeign(..) => {
 507                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 508             }
 509             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 510                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 511             }
 512             Def::StructCtor(..) => {
 513                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 514
 515                 if let Some(struct_def_id) =
 516                         self.cstore.def_key(def_id).parent
 517                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 518                     self.struct_constructors.insert(struct_def_id, (def, vis));
 519                 }
 520             }
 521             Def::Trait(..) => {
 522                 let module_kind = ModuleKind::Def(def, ident.name);
 523                 let module = self.new_module(parent,
 524                                              module_kind,
 525                                              parent.normal_ancestor_id,
 526                                              expansion,
 527                                              span);
 528                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 529
 530                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 531                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 532                     self.define(module, child.ident, ns,
 533                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 534
 535                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 536                            .method_has_self_argument {
 537                         self.has_self.insert(child.def.def_id());
 538                     }
 539                 }
 540                 module.populated.set(true);
 541             }
 542             Def::Struct(..) | Def::Union(..) => {
 543                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 544
 545                 // Record field names for error reporting.
 546                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 547                 self.insert_field_names(def_id, field_names);
 548             }
 549             Def::Macro(..) => {
 550                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 551             }
 552             _ => bug!("unexpected definition: {:?}", def)
 553         }
 554     }
 555
 556     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 557         if def_id.krate == LOCAL_CRATE {
 558             return self.module_map[&def_id]
 559         }
 560
 561         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 562         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 563             return module;
 564         }
 565
 566         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 567             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 568         } else {
 569             let def_key = self.cstore.def_key(def_id);
 570             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 571              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 572         };
 573
 574         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 575         let module =
 576             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 577         self.extern_module_map.insert((def_id, macros_only), module);
 578         module
 579     }
 580
 581     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 582         let def_id = self.macro_defs[&expansion];
 583         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 584             self.local_macro_def_scopes[&id]
 585         } else if def_id.krate == BUILTIN_MACROS_CRATE {
 586             self.injected_crate.unwrap_or(self.graph_root)
 587         } else {
 588             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 589             self.get_module(module_def_id)
 590         }
 591     }
 592
 593     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 594         let def_id = match def {
 595             Def::Macro(def_id, ..) => def_id,
 596             _ => panic!("Expected Def::Macro(..)"),
 597         };
 598         if let Some(ext) = self.macro_map.get(&def_id) {
 599             return ext.clone();
 600         }
 601
 602         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 603             LoadedMacro::MacroDef(macro_def) => macro_def,
 604             LoadedMacro::ProcMacro(ext) => return ext,
 605         };
 606
 607         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 608                                                &self.session.features_untracked(),
 609                                                &macro_def,
 610                                                self.cstore.crate_edition_untracked(def_id.krate)));
 611         self.macro_map.insert(def_id, ext.clone());
 612         ext
 613     }
 614
 615     /// Ensures that the reduced graph rooted at the given external module
 616     /// is built, building it if it is not.
 617     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 618         if module.populated.get() { return }
 619         let def_id = module.def_id().unwrap();
 620         for child in self.cstore.item_children_untracked(def_id, self.session) {
 621             self.build_reduced_graph_for_external_crate_def(module, child);
 622         }
 623         module.populated.set(true)
 624     }
 625
 626     fn legacy_import_macro(&mut self,
 627                            name: Name,
 628                            binding: &'a NameBinding<'a>,
 629                            span: Span,
 630                            allow_shadowing: bool) {
 631         if self.global_macros.insert(name, binding).is_some() && !allow_shadowing {
 632             let msg = format!("`{}` is already in scope", name);
 633             let note =
 634                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 635             self.session.struct_span_err(span, &msg).note(note).emit();
 636         }
 637     }
 638
 639     // This returns true if we should consider the underlying `extern crate` to be used.
 640     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>, expansion: Mark)
 641                                     -> bool {
 642         let allow_shadowing = expansion == Mark::root();
 643         let legacy_imports = self.legacy_macro_imports(&item.attrs);
 644         let mut used = legacy_imports != LegacyMacroImports::default();
 645
 646         // `#[macro_use]` is only allowed at the crate root.
 647         if self.current_module.parent.is_some() && used {
 648             span_err!(self.session, item.span, E0468,
 649                       "an `extern crate` loading macros must be at the crate root");
 650         } else if !self.use_extern_macros && !used &&
 651                   self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
 652                       .macros_only() {
 653             let msg = "proc macro crates and `#[no_link]` crates have no effect without \
 654                        `#[macro_use]`";
 655             self.session.span_warn(item.span, msg);
 656             used = true; // Avoid the normal unused extern crate warning
 657         }
 658
 659         let (graph_root, arenas) = (self.graph_root, self.arenas);
 660         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 661             root_id: item.id,
 662             id: item.id,
 663             parent: graph_root,
 664             imported_module: Cell::new(Some(module)),
 665             subclass: ImportDirectiveSubclass::MacroUse,
 666             root_span: span,
 667             span,
 668             module_path: Vec::new(),
 669             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 670             expansion,
 671             used: Cell::new(false),
 672         });
 673
 674         if let Some(span) = legacy_imports.import_all {
 675             let directive = macro_use_directive(span);
 676             self.potentially_unused_imports.push(directive);
 677             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 678                 let imported_binding = self.import(binding, directive);
 679                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 680             });
 681         } else {
 682             for (name, span) in legacy_imports.imports {
 683                 let ident = Ident::with_empty_ctxt(name);
 684                 let result = self.resolve_ident_in_module(module, ident, MacroNS,
 685                                                           false, false, span);
 686                 if let Ok(binding) = result {
 687                     let directive = macro_use_directive(span);
 688                     self.potentially_unused_imports.push(directive);
 689                     let imported_binding = self.import(binding, directive);
 690                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 691                 } else {
 692                     span_err!(self.session, span, E0469, "imported macro not found");
 693                 }
 694             }
 695         }
 696         used
 697     }
 698
 699     // does this attribute list contain "macro_use"?
 700     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 701         for attr in attrs {
 702             if attr.check_name("macro_escape") {
 703                 let msg = "macro_escape is a deprecated synonym for macro_use";
 704                 let mut err = self.session.struct_span_warn(attr.span, msg);
 705                 if let ast::AttrStyle::Inner = attr.style {
 706                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 707                 } else {
 708                     err.emit();
 709                 }
 710             } else if !attr.check_name("macro_use") {
 711                 continue;
 712             }
 713
 714             if !attr.is_word() {
 715                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 716             }
 717             return true;
 718         }
 719
 720         false
 721     }
 722
 723     fn legacy_macro_imports(&mut self, attrs: &[ast::Attribute]) -> LegacyMacroImports {
 724         let mut imports = LegacyMacroImports::default();
 725         for attr in attrs {
 726             if attr.check_name("macro_use") {
 727                 match attr.meta_item_list() {
 728                     Some(names) => for attr in names {
 729                         if let Some(word) = attr.word() {
 730                             imports.imports.push((word.name(), attr.span()));
 731                         } else {
 732                             span_err!(self.session, attr.span(), E0466, "bad macro import");
 733                         }
 734                     },
 735                     None => imports.import_all = Some(attr.span),
 736                 }
 737             }
 738         }
 739         imports
 740     }
 741 }
 742
 743 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 744     pub resolver: &'a mut Resolver<'b>,
 745     pub legacy_scope: LegacyScope<'b>,
 746     pub expansion: Mark,
 747 }
 748
 749 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 750     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 751         let mark = id.placeholder_to_mark();
 752         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 753         let invocation = self.resolver.invocations[&mark];
 754         invocation.module.set(self.resolver.current_module);
 755         invocation.legacy_scope.set(self.legacy_scope);
 756         invocation
 757     }
 758 }
 759
 760 macro_rules! method {
 761     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 762         fn $visit(&mut self, node: &'a $ty) {
 763             if let $invoc(..) = node.node {
 764                 self.visit_invoc(node.id);
 765             } else {
 766                 visit::$walk(self, node);
 767             }
 768         }
 769     }
 770 }
 771
 772 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 773     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 774     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 775     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 776     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 777
 778     fn visit_item(&mut self, item: &'a Item) {
 779         let macro_use = match item.node {
 780             ItemKind::MacroDef(..) => {
 781                 self.resolver.define_macro(item, self.expansion, &mut self.legacy_scope);
 782                 return
 783             }
 784             ItemKind::Mac(..) => {
 785                 self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
 786                 return
 787             }
 788             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 789             _ => false,
 790         };
 791
 792         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 793         self.resolver.build_reduced_graph_for_item(item, self.expansion);
 794         visit::walk_item(self, item);
 795         self.resolver.current_module = parent;
 796         if !macro_use {
 797             self.legacy_scope = legacy_scope;
 798         }
 799     }
 800
 801     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 802         if let ast::StmtKind::Mac(..) = stmt.node {
 803             self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(stmt.id));
 804         } else {
 805             visit::walk_stmt(self, stmt);
 806         }
 807     }
 808
 809     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 810         if let ForeignItemKind::Macro(_) = foreign_item.node {
 811             self.visit_invoc(foreign_item.id);
 812             return;
 813         }
 814
 815         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 816         visit::walk_foreign_item(self, foreign_item);
 817     }
 818
 819     fn visit_block(&mut self, block: &'a Block) {
 820         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 821         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 822         visit::walk_block(self, block);
 823         self.resolver.current_module = parent;
 824         self.legacy_scope = legacy_scope;
 825     }
 826
 827     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 828         let parent = self.resolver.current_module;
 829
 830         if let TraitItemKind::Macro(_) = item.node {
 831             self.visit_invoc(item.id);
 832             return
 833         }
 834
 835         // Add the item to the trait info.
 836         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 837         let (def, ns) = match item.node {
 838             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 839             TraitItemKind::Method(ref sig, _) => {
 840                 if sig.decl.has_self() {
 841                     self.resolver.has_self.insert(item_def_id);
 842                 }
 843                 (Def::Method(item_def_id), ValueNS)
 844             }
 845             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 846             TraitItemKind::Macro(_) => bug!(),  // handled above
 847         };
 848
 849         let vis = ty::Visibility::Public;
 850         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 851
 852         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 853         visit::walk_trait_item(self, item);
 854         self.resolver.current_module = parent;
 855     }
 856
 857     fn visit_token(&mut self, t: Token) {
 858         if let Token::Interpolated(nt) = t {
 859             match nt.0 {
 860                 token::NtExpr(ref expr) => {
 861                     if let ast::ExprKind::Mac(..) = expr.node {
 862                         self.visit_invoc(expr.id);
 863                     }
 864                 }
 865                 _ => {}
 866             }
 867         }
 868     }
 869 }