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 {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 std::rc::Rc;
  31
  32 use syntax::ast::{Name, Ident};
  33 use syntax::attr;
  34
  35 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind};
  36 use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind};
  37 use syntax::ast::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  38 use syntax::codemap::respan;
  39 use syntax::ext::base::SyntaxExtension;
  40 use syntax::ext::base::Determinacy::Undetermined;
  41 use syntax::ext::hygiene::Mark;
  42 use syntax::ext::tt::macro_rules;
  43 use syntax::parse::token;
  44 use syntax::symbol::keywords;
  45 use syntax::symbol::Symbol;
  46 use syntax::visit::{self, Visitor};
  47
  48 use syntax_pos::{Span, DUMMY_SP};
  49
  50 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  51     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  52         arenas.alloc_name_binding(NameBinding {
  53             kind: NameBindingKind::Module(self.0),
  54             vis: self.1,
  55             span: self.2,
  56             expansion: self.3,
  57         })
  58     }
  59 }
  60
  61 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  62     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  63         arenas.alloc_name_binding(NameBinding {
  64             kind: NameBindingKind::Def(self.0),
  65             vis: self.1,
  66             span: self.2,
  67             expansion: self.3,
  68         })
  69     }
  70 }
  71
  72 #[derive(Default, PartialEq, Eq)]
  73 struct LegacyMacroImports {
  74     import_all: Option<Span>,
  75     imports: Vec<(Name, Span)>,
  76     reexports: Vec<(Name, Span)>,
  77 }
  78
  79 impl<'a> Resolver<'a> {
  80     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  81     /// otherwise, reports an error.
  82     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  83         where T: ToNameBinding<'a>,
  84     {
  85         let binding = def.to_name_binding(self.arenas);
  86         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  87             self.report_conflict(parent, ident, ns, old_binding, &binding);
  88         }
  89     }
  90
  91     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  92         // If any statements are items, we need to create an anonymous module
  93         block.stmts.iter().any(|statement| match statement.node {
  94             StmtKind::Item(_) | StmtKind::Mac(_) => true,
  95             _ => false,
  96         })
  97     }
  98
  99     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 100         if !field_names.is_empty() {
 101             self.field_names.insert(def_id, field_names);
 102         }
 103     }
 104
 105     /// Constructs the reduced graph for one item.
 106     fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
 107         let parent = self.current_module;
 108         let ident = item.ident;
 109         let sp = item.span;
 110         let vis = self.resolve_visibility(&item.vis);
 111
 112         match item.node {
 113             ItemKind::Use(ref view_path) => {
 114                 // Extract and intern the module part of the path. For
 115                 // globs and lists, the path is found directly in the AST;
 116                 // for simple paths we have to munge the path a little.
 117                 let mut module_path: Vec<_> = match view_path.node {
 118                     ViewPathSimple(_, ref full_path) => {
 119                         full_path.segments
 120                                  .split_last()
 121                                  .unwrap()
 122                                  .1
 123                                  .iter()
 124                                  .map(|seg| respan(seg.span, seg.identifier))
 125                                  .collect()
 126                     }
 127
 128                     ViewPathGlob(ref module_ident_path) |
 129                     ViewPathList(ref module_ident_path, _) => {
 130                         module_ident_path.segments
 131                                          .iter()
 132                                          .map(|seg| respan(seg.span, seg.identifier))
 133                                          .collect()
 134                     }
 135                 };
 136
 137                 // This can be removed once warning cycle #36888 is complete.
 138                 if module_path.len() >= 2 &&
 139                     module_path[0].node.name == keywords::CrateRoot.name() &&
 140                     token::Ident(module_path[1].node).is_path_segment_keyword()
 141                 {
 142                     module_path.remove(0);
 143                 }
 144
 145                 // Build up the import directives.
 146                 let is_prelude = attr::contains_name(&item.attrs, "prelude_import");
 147
 148                 match view_path.node {
 149                     ViewPathSimple(mut binding, ref full_path) => {
 150                         let mut source = full_path.segments.last().unwrap().identifier;
 151                         let source_name = source.name;
 152                         if source_name == "mod" || source_name == "self" {
 153                             resolve_error(self,
 154                                           view_path.span,
 155                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 156                         } else if source_name == keywords::DollarCrate.name() &&
 157                                   full_path.segments.len() == 1 {
 158                             let crate_root = self.resolve_crate_root(source.ctxt);
 159                             let crate_name = match crate_root.kind {
 160                                 ModuleKind::Def(_, name) => name,
 161                                 ModuleKind::Block(..) => unreachable!(),
 162                             };
 163                             source.name = crate_name;
 164                             if binding.name == keywords::DollarCrate.name() {
 165                                 binding.name = crate_name;
 166                             }
 167
 168                             self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 169                                 .note("`use $crate;` was erroneously allowed and \
 170                                        will become a hard error in a future release")
 171                                 .emit();
 172                         }
 173
 174                         let subclass = SingleImport {
 175                             target: binding,
 176                             source,
 177                             result: self.per_ns(|_, _| Cell::new(Err(Undetermined))),
 178                             type_ns_only: false,
 179                         };
 180                         self.add_import_directive(
 181                             module_path, subclass, view_path.span, item.id, vis, expansion,
 182                         );
 183                     }
 184                     ViewPathList(_, ref source_items) => {
 185                         // Make sure there's at most one `mod` import in the list.
 186                         let mod_spans = source_items.iter().filter_map(|item| {
 187                             if item.node.name.name == keywords::SelfValue.name() {
 188                                 Some(item.span)
 189                             } else {
 190                                 None
 191                             }
 192                         }).collect::<Vec<Span>>();
 193
 194                         if mod_spans.len() > 1 {
 195                             let mut e = resolve_struct_error(self,
 196                                           mod_spans[0],
 197                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 198                             for other_span in mod_spans.iter().skip(1) {
 199                                 e.span_note(*other_span, "another `self` import appears here");
 200                             }
 201                             e.emit();
 202                         }
 203
 204                         for source_item in source_items {
 205                             let node = source_item.node;
 206                             let (module_path, ident, rename, type_ns_only) = {
 207                                 if node.name.name != keywords::SelfValue.name() {
 208                                     let rename = node.rename.unwrap_or(node.name);
 209                                     (module_path.clone(),
 210                                      respan(source_item.span, node.name),
 211                                      rename,
 212                                      false)
 213                                 } else {
 214                                     let ident = *module_path.last().unwrap();
 215                                     if ident.node.name == keywords::CrateRoot.name() {
 216                                         resolve_error(
 217                                             self,
 218                                             source_item.span,
 219                                             ResolutionError::
 220                                             SelfImportOnlyInImportListWithNonEmptyPrefix
 221                                         );
 222                                         continue;
 223                                     }
 224                                     let module_path = module_path.split_last().unwrap().1;
 225                                     let rename = node.rename.unwrap_or(ident.node);
 226                                     (module_path.to_vec(), ident, rename, true)
 227                                 }
 228                             };
 229                             let subclass = SingleImport {
 230                                 target: rename,
 231                                 source: ident.node,
 232                                 result: self.per_ns(|_, _| Cell::new(Err(Undetermined))),
 233                                 type_ns_only,
 234                             };
 235                             let id = source_item.node.id;
 236                             self.add_import_directive(
 237                                 module_path, subclass, source_item.span, id, vis, expansion,
 238                             );
 239                         }
 240                     }
 241                     ViewPathGlob(_) => {
 242                         let subclass = GlobImport {
 243                             is_prelude,
 244                             max_vis: Cell::new(ty::Visibility::Invisible),
 245                         };
 246                         self.add_import_directive(
 247                             module_path, subclass, view_path.span, item.id, vis, expansion,
 248                         );
 249                     }
 250                 }
 251             }
 252
 253             ItemKind::ExternCrate(_) => {
 254                 self.crate_loader.process_item(item, &self.definitions);
 255
 256                 // n.b. we don't need to look at the path option here, because cstore already did
 257                 let crate_id = self.cstore.extern_mod_stmt_cnum_untracked(item.id).unwrap();
 258                 let module =
 259                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 260                 self.populate_module_if_necessary(module);
 261                 let used = self.process_legacy_macro_imports(item, module, expansion);
 262                 let binding =
 263                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 264                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 265                     id: item.id,
 266                     parent,
 267                     imported_module: Cell::new(Some(module)),
 268                     subclass: ImportDirectiveSubclass::ExternCrate,
 269                     span: item.span,
 270                     module_path: Vec::new(),
 271                     vis: Cell::new(vis),
 272                     expansion,
 273                     used: Cell::new(used),
 274                 });
 275                 self.potentially_unused_imports.push(directive);
 276                 let imported_binding = self.import(binding, directive);
 277                 self.define(parent, ident, TypeNS, imported_binding);
 278             }
 279
 280             ItemKind::GlobalAsm(..) => {}
 281
 282             ItemKind::Mod(..) if item.ident == keywords::Invalid.ident() => {} // Crate root
 283
 284             ItemKind::Mod(..) => {
 285                 let def_id = self.definitions.local_def_id(item.id);
 286                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 287                 let module = self.arenas.alloc_module(ModuleData {
 288                     no_implicit_prelude: parent.no_implicit_prelude || {
 289                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 290                     },
 291                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 292                 });
 293                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 294                 self.module_map.insert(def_id, module);
 295
 296                 // Descend into the module.
 297                 self.current_module = module;
 298             }
 299
 300             ItemKind::ForeignMod(..) => self.crate_loader.process_item(item, &self.definitions),
 301
 302             // These items live in the value namespace.
 303             ItemKind::Static(_, m, _) => {
 304                 let mutbl = m == Mutability::Mutable;
 305                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 306                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 307             }
 308             ItemKind::Const(..) => {
 309                 let def = Def::Const(self.definitions.local_def_id(item.id));
 310                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 311             }
 312             ItemKind::Fn(..) => {
 313                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 314                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 315             }
 316
 317             // These items live in the type namespace.
 318             ItemKind::Ty(..) => {
 319                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 320                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 321             }
 322
 323             ItemKind::Enum(ref enum_definition, _) => {
 324                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 325                 let module_kind = ModuleKind::Def(def, ident.name);
 326                 let module = self.new_module(parent,
 327                                              module_kind,
 328                                              parent.normal_ancestor_id,
 329                                              expansion,
 330                                              item.span);
 331                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 332
 333                 for variant in &(*enum_definition).variants {
 334                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 335                 }
 336             }
 337
 338             // These items live in both the type and value namespaces.
 339             ItemKind::Struct(ref struct_def, _) => {
 340                 // Define a name in the type namespace.
 341                 let def = Def::Struct(self.definitions.local_def_id(item.id));
 342                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 343
 344                 // Record field names for error reporting.
 345                 let mut ctor_vis = vis;
 346                 let field_names = struct_def.fields().iter().filter_map(|field| {
 347                     let field_vis = self.resolve_visibility(&field.vis);
 348                     if ctor_vis.is_at_least(field_vis, &*self) {
 349                         ctor_vis = field_vis;
 350                     }
 351                     field.ident.map(|ident| ident.name)
 352                 }).collect();
 353                 let item_def_id = self.definitions.local_def_id(item.id);
 354                 self.insert_field_names(item_def_id, field_names);
 355
 356                 // If this is a tuple or unit struct, define a name
 357                 // in the value namespace as well.
 358                 if !struct_def.is_struct() {
 359                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 360                                                    CtorKind::from_ast(struct_def));
 361                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 362                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 363                 }
 364             }
 365
 366             ItemKind::Union(ref vdata, _) => {
 367                 let def = Def::Union(self.definitions.local_def_id(item.id));
 368                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 369
 370                 // Record field names for error reporting.
 371                 let field_names = vdata.fields().iter().filter_map(|field| {
 372                     self.resolve_visibility(&field.vis);
 373                     field.ident.map(|ident| ident.name)
 374                 }).collect();
 375                 let item_def_id = self.definitions.local_def_id(item.id);
 376                 self.insert_field_names(item_def_id, field_names);
 377             }
 378
 379             ItemKind::DefaultImpl(..) | ItemKind::Impl(..) => {}
 380
 381             ItemKind::Trait(..) => {
 382                 let def_id = self.definitions.local_def_id(item.id);
 383
 384                 // Add all the items within to a new module.
 385                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 386                 let module = self.new_module(parent,
 387                                              module_kind,
 388                                              parent.normal_ancestor_id,
 389                                              expansion,
 390                                              item.span);
 391                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 392                 self.current_module = module;
 393             }
 394             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 395         }
 396     }
 397
 398     // Constructs the reduced graph for one variant. Variants exist in the
 399     // type and value namespaces.
 400     fn build_reduced_graph_for_variant(&mut self,
 401                                        variant: &Variant,
 402                                        parent: Module<'a>,
 403                                        vis: ty::Visibility,
 404                                        expansion: Mark) {
 405         let ident = variant.node.name;
 406         let def_id = self.definitions.local_def_id(variant.node.data.id());
 407
 408         // Define a name in the type namespace.
 409         let def = Def::Variant(def_id);
 410         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 411
 412         // Define a constructor name in the value namespace.
 413         // Braced variants, unlike structs, generate unusable names in
 414         // value namespace, they are reserved for possible future use.
 415         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 416         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 417         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 418     }
 419
 420     /// Constructs the reduced graph for one foreign item.
 421     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 422         let def = match item.node {
 423             ForeignItemKind::Fn(..) => {
 424                 Def::Fn(self.definitions.local_def_id(item.id))
 425             }
 426             ForeignItemKind::Static(_, m) => {
 427                 Def::Static(self.definitions.local_def_id(item.id), m)
 428             }
 429         };
 430         let parent = self.current_module;
 431         let vis = self.resolve_visibility(&item.vis);
 432         self.define(parent, item.ident, ValueNS, (def, vis, item.span, expansion));
 433     }
 434
 435     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 436         let parent = self.current_module;
 437         if self.block_needs_anonymous_module(block) {
 438             let module = self.new_module(parent,
 439                                          ModuleKind::Block(block.id),
 440                                          parent.normal_ancestor_id,
 441                                          expansion,
 442                                          block.span);
 443             self.block_map.insert(block.id, module);
 444             self.current_module = module; // Descend into the block.
 445         }
 446     }
 447
 448     /// Builds the reduced graph for a single item in an external crate.
 449     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 450         let ident = child.ident;
 451         let def = child.def;
 452         let def_id = def.def_id();
 453         let vis = self.cstore.visibility_untracked(def_id);
 454         let span = child.span;
 455         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 456         match def {
 457             Def::Mod(..) | Def::Enum(..) => {
 458                 let module = self.new_module(parent,
 459                                              ModuleKind::Def(def, ident.name),
 460                                              def_id,
 461                                              expansion,
 462                                              span);
 463                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 464             }
 465             Def::Variant(..) | Def::TyAlias(..) => {
 466                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 467             }
 468             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 469                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 470             }
 471             Def::StructCtor(..) => {
 472                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 473
 474                 if let Some(struct_def_id) =
 475                         self.cstore.def_key(def_id).parent
 476                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 477                     self.struct_constructors.insert(struct_def_id, (def, vis));
 478                 }
 479             }
 480             Def::Trait(..) => {
 481                 let module_kind = ModuleKind::Def(def, ident.name);
 482                 let module = self.new_module(parent,
 483                                              module_kind,
 484                                              parent.normal_ancestor_id,
 485                                              expansion,
 486                                              span);
 487                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 488
 489                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 490                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 491                     self.define(module, child.ident, ns,
 492                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 493
 494                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 495                            .method_has_self_argument {
 496                         self.has_self.insert(child.def.def_id());
 497                     }
 498                 }
 499                 module.populated.set(true);
 500             }
 501             Def::Struct(..) | Def::Union(..) => {
 502                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 503
 504                 // Record field names for error reporting.
 505                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 506                 self.insert_field_names(def_id, field_names);
 507             }
 508             Def::Macro(..) => {
 509                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 510             }
 511             _ => bug!("unexpected definition: {:?}", def)
 512         }
 513     }
 514
 515     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 516         if def_id.krate == LOCAL_CRATE {
 517             return self.module_map[&def_id]
 518         }
 519
 520         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 521         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 522             return module;
 523         }
 524
 525         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 526             (self.cstore.crate_name_untracked(def_id.krate).as_str(), None)
 527         } else {
 528             let def_key = self.cstore.def_key(def_id);
 529             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 530              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 531         };
 532
 533         let kind = ModuleKind::Def(Def::Mod(def_id), Symbol::intern(&name));
 534         let module =
 535             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 536         self.extern_module_map.insert((def_id, macros_only), module);
 537         module
 538     }
 539
 540     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 541         let def_id = self.macro_defs[&expansion];
 542         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 543             self.local_macro_def_scopes[&id]
 544         } else if def_id.krate == BUILTIN_MACROS_CRATE {
 545             // FIXME(jseyfried): This happens when `include!()`ing a `$crate::` path, c.f, #40469.
 546             self.graph_root
 547         } else {
 548             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 549             self.get_module(module_def_id)
 550         }
 551     }
 552
 553     pub fn get_macro(&mut self, def: Def) -> Rc<SyntaxExtension> {
 554         let def_id = match def {
 555             Def::Macro(def_id, ..) => def_id,
 556             _ => panic!("Expected Def::Macro(..)"),
 557         };
 558         if let Some(ext) = self.macro_map.get(&def_id) {
 559             return ext.clone();
 560         }
 561
 562         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 563             LoadedMacro::MacroDef(macro_def) => macro_def,
 564             LoadedMacro::ProcMacro(ext) => return ext,
 565         };
 566
 567         let ext = Rc::new(macro_rules::compile(&self.session.parse_sess,
 568                                                &self.session.features,
 569                                                &macro_def));
 570         self.macro_map.insert(def_id, ext.clone());
 571         ext
 572     }
 573
 574     /// Ensures that the reduced graph rooted at the given external module
 575     /// is built, building it if it is not.
 576     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 577         if module.populated.get() { return }
 578         let def_id = module.def_id().unwrap();
 579         for child in self.cstore.item_children_untracked(def_id, self.session) {
 580             self.build_reduced_graph_for_external_crate_def(module, child);
 581         }
 582         module.populated.set(true)
 583     }
 584
 585     fn legacy_import_macro(&mut self,
 586                            name: Name,
 587                            binding: &'a NameBinding<'a>,
 588                            span: Span,
 589                            allow_shadowing: bool) {
 590         if self.global_macros.insert(name, binding).is_some() && !allow_shadowing {
 591             let msg = format!("`{}` is already in scope", name);
 592             let note =
 593                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 594             self.session.struct_span_err(span, &msg).note(note).emit();
 595         }
 596     }
 597
 598     // This returns true if we should consider the underlying `extern crate` to be used.
 599     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>, expansion: Mark)
 600                                     -> bool {
 601         let allow_shadowing = expansion == Mark::root();
 602         let legacy_imports = self.legacy_macro_imports(&item.attrs);
 603         let mut used = legacy_imports != LegacyMacroImports::default();
 604
 605         // `#[macro_use]` and `#[macro_reexport]` are only allowed at the crate root.
 606         if self.current_module.parent.is_some() && used {
 607             span_err!(self.session, item.span, E0468,
 608                       "an `extern crate` loading macros must be at the crate root");
 609         } else if !self.use_extern_macros && !used &&
 610                   self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
 611                       .macros_only() {
 612             let msg = "proc macro crates and `#[no_link]` crates have no effect without \
 613                        `#[macro_use]`";
 614             self.session.span_warn(item.span, msg);
 615             used = true; // Avoid the normal unused extern crate warning
 616         }
 617
 618         let (graph_root, arenas) = (self.graph_root, self.arenas);
 619         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 620             id: item.id,
 621             parent: graph_root,
 622             imported_module: Cell::new(Some(module)),
 623             subclass: ImportDirectiveSubclass::MacroUse,
 624             span,
 625             module_path: Vec::new(),
 626             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 627             expansion,
 628             used: Cell::new(false),
 629         });
 630
 631         if let Some(span) = legacy_imports.import_all {
 632             let directive = macro_use_directive(span);
 633             self.potentially_unused_imports.push(directive);
 634             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 635                 let imported_binding = self.import(binding, directive);
 636                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 637             });
 638         } else {
 639             for (name, span) in legacy_imports.imports {
 640                 let ident = Ident::with_empty_ctxt(name);
 641                 let result = self.resolve_ident_in_module(module, ident, MacroNS,
 642                                                           false, false, span);
 643                 if let Ok(binding) = result {
 644                     let directive = macro_use_directive(span);
 645                     self.potentially_unused_imports.push(directive);
 646                     let imported_binding = self.import(binding, directive);
 647                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 648                 } else {
 649                     span_err!(self.session, span, E0469, "imported macro not found");
 650                 }
 651             }
 652         }
 653         for (name, span) in legacy_imports.reexports {
 654             self.cstore.export_macros_untracked(module.def_id().unwrap().krate);
 655             let ident = Ident::with_empty_ctxt(name);
 656             let result = self.resolve_ident_in_module(module, ident, MacroNS, false, false, span);
 657             if let Ok(binding) = result {
 658                 self.macro_exports.push(Export { ident: ident, def: binding.def(), span: span });
 659             } else {
 660                 span_err!(self.session, span, E0470, "reexported macro not found");
 661             }
 662         }
 663         used
 664     }
 665
 666     // does this attribute list contain "macro_use"?
 667     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 668         for attr in attrs {
 669             if attr.check_name("macro_escape") {
 670                 let msg = "macro_escape is a deprecated synonym for macro_use";
 671                 let mut err = self.session.struct_span_warn(attr.span, msg);
 672                 if let ast::AttrStyle::Inner = attr.style {
 673                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 674                 } else {
 675                     err.emit();
 676                 }
 677             } else if !attr.check_name("macro_use") {
 678                 continue;
 679             }
 680
 681             if !attr.is_word() {
 682                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 683             }
 684             return true;
 685         }
 686
 687         false
 688     }
 689
 690     fn legacy_macro_imports(&mut self, attrs: &[ast::Attribute]) -> LegacyMacroImports {
 691         let mut imports = LegacyMacroImports::default();
 692         for attr in attrs {
 693             if attr.check_name("macro_use") {
 694                 match attr.meta_item_list() {
 695                     Some(names) => for attr in names {
 696                         if let Some(word) = attr.word() {
 697                             imports.imports.push((word.name(), attr.span()));
 698                         } else {
 699                             span_err!(self.session, attr.span(), E0466, "bad macro import");
 700                         }
 701                     },
 702                     None => imports.import_all = Some(attr.span),
 703                 }
 704             } else if attr.check_name("macro_reexport") {
 705                 let bad_macro_reexport = |this: &mut Self, span| {
 706                     span_err!(this.session, span, E0467, "bad macro reexport");
 707                 };
 708                 if let Some(names) = attr.meta_item_list() {
 709                     for attr in names {
 710                         if let Some(word) = attr.word() {
 711                             imports.reexports.push((word.name(), attr.span()));
 712                         } else {
 713                             bad_macro_reexport(self, attr.span());
 714                         }
 715                     }
 716                 } else {
 717                     bad_macro_reexport(self, attr.span());
 718                 }
 719             }
 720         }
 721         imports
 722     }
 723 }
 724
 725 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 726     pub resolver: &'a mut Resolver<'b>,
 727     pub legacy_scope: LegacyScope<'b>,
 728     pub expansion: Mark,
 729 }
 730
 731 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 732     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 733         let mark = id.placeholder_to_mark();
 734         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 735         let invocation = self.resolver.invocations[&mark];
 736         invocation.module.set(self.resolver.current_module);
 737         invocation.legacy_scope.set(self.legacy_scope);
 738         invocation
 739     }
 740 }
 741
 742 macro_rules! method {
 743     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 744         fn $visit(&mut self, node: &'a $ty) {
 745             if let $invoc(..) = node.node {
 746                 self.visit_invoc(node.id);
 747             } else {
 748                 visit::$walk(self, node);
 749             }
 750         }
 751     }
 752 }
 753
 754 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 755     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 756     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 757     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 758     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 759
 760     fn visit_item(&mut self, item: &'a Item) {
 761         let macro_use = match item.node {
 762             ItemKind::MacroDef(..) => {
 763                 self.resolver.define_macro(item, self.expansion, &mut self.legacy_scope);
 764                 return
 765             }
 766             ItemKind::Mac(..) => {
 767                 self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
 768                 return
 769             }
 770             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 771             _ => false,
 772         };
 773
 774         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 775         self.resolver.build_reduced_graph_for_item(item, self.expansion);
 776         visit::walk_item(self, item);
 777         self.resolver.current_module = parent;
 778         if !macro_use {
 779             self.legacy_scope = legacy_scope;
 780         }
 781     }
 782
 783     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 784         if let ast::StmtKind::Mac(..) = stmt.node {
 785             self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(stmt.id));
 786         } else {
 787             visit::walk_stmt(self, stmt);
 788         }
 789     }
 790
 791     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 792         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 793         visit::walk_foreign_item(self, foreign_item);
 794     }
 795
 796     fn visit_block(&mut self, block: &'a Block) {
 797         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 798         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 799         visit::walk_block(self, block);
 800         self.resolver.current_module = parent;
 801         self.legacy_scope = legacy_scope;
 802     }
 803
 804     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 805         let parent = self.resolver.current_module;
 806
 807         if let TraitItemKind::Macro(_) = item.node {
 808             self.visit_invoc(item.id);
 809             return
 810         }
 811
 812         // Add the item to the trait info.
 813         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 814         let (def, ns) = match item.node {
 815             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 816             TraitItemKind::Method(ref sig, _) => {
 817                 if sig.decl.has_self() {
 818                     self.resolver.has_self.insert(item_def_id);
 819                 }
 820                 (Def::Method(item_def_id), ValueNS)
 821             }
 822             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 823             TraitItemKind::Macro(_) => bug!(),  // handled above
 824         };
 825
 826         let vis = ty::Visibility::Public;
 827         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 828
 829         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 830         visit::walk_trait_item(self, item);
 831         self.resolver.current_module = parent;
 832     }
 833 }