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::hir::def::*;
  25 use rustc::hir::def_id::{BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  26 use rustc::ty;
  27 use rustc::middle::cstore::CrateStore;
  28 use rustc_metadata::cstore::LoadedMacro;
  29
  30 use std::cell::Cell;
  31 use rustc_data_structures::sync::Lrc;
  32
  33 use syntax::ast::{Name, Ident};
  34 use syntax::attr;
  35
  36 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  37 use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  38 use syntax::ext::base::{MacroKind, SyntaxExtension};
  39 use syntax::ext::base::Determinacy::Undetermined;
  40 use syntax::ext::hygiene::Mark;
  41 use syntax::ext::tt::macro_rules;
  42 use syntax::parse::token::{self, Token};
  43 use syntax::std_inject::injected_crate_name;
  44 use syntax::symbol::keywords;
  45 use syntax::visit::{self, Visitor};
  46
  47 use syntax_pos::{Span, DUMMY_SP};
  48
  49 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  50     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  51         arenas.alloc_name_binding(NameBinding {
  52             kind: NameBindingKind::Module(self.0),
  53             vis: self.1,
  54             span: self.2,
  55             expansion: self.3,
  56         })
  57     }
  58 }
  59
  60 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  61     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  62         arenas.alloc_name_binding(NameBinding {
  63             kind: NameBindingKind::Def(self.0, false),
  64             vis: self.1,
  65             span: self.2,
  66             expansion: self.3,
  67         })
  68     }
  69 }
  70
  71 pub(crate) struct IsMacroExport;
  72
  73 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark, IsMacroExport) {
  74     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  75         arenas.alloc_name_binding(NameBinding {
  76             kind: NameBindingKind::Def(self.0, true),
  77             vis: self.1,
  78             span: self.2,
  79             expansion: self.3,
  80         })
  81     }
  82 }
  83
  84 #[derive(Default, PartialEq, Eq)]
  85 struct LegacyMacroImports {
  86     import_all: Option<Span>,
  87     imports: Vec<(Name, Span)>,
  88 }
  89
  90 impl<'a, 'cl> Resolver<'a, 'cl> {
  91     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  92     /// otherwise, reports an error.
  93     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  94         where T: ToNameBinding<'a>,
  95     {
  96         let binding = def.to_name_binding(self.arenas);
  97         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  98             self.report_conflict(parent, ident, ns, old_binding, &binding);
  99         }
 100     }
 101
 102     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 103         // If any statements are items, we need to create an anonymous module
 104         block.stmts.iter().any(|statement| match statement.node {
 105             StmtKind::Item(_) | StmtKind::Mac(_) => true,
 106             _ => false,
 107         })
 108     }
 109
 110     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 111         if !field_names.is_empty() {
 112             self.field_names.insert(def_id, field_names);
 113         }
 114     }
 115
 116     fn build_reduced_graph_for_use_tree(&mut self,
 117                                         root_use_tree: &ast::UseTree,
 118                                         root_id: NodeId,
 119                                         use_tree: &ast::UseTree,
 120                                         id: NodeId,
 121                                         vis: ty::Visibility,
 122                                         prefix: &ast::Path,
 123                                         nested: bool,
 124                                         item: &Item,
 125                                         expansion: Mark) {
 126         let is_prelude = attr::contains_name(&item.attrs, "prelude_import");
 127         let path = &use_tree.prefix;
 128
 129         let mut module_path: Vec<_> = prefix.segments.iter()
 130             .chain(path.segments.iter())
 131             .map(|seg| seg.ident)
 132             .collect();
 133
 134         match use_tree.kind {
 135             ast::UseTreeKind::Simple(rename, ..) => {
 136                 let mut ident = use_tree.ident();
 137                 let mut source = module_path.pop().unwrap();
 138                 let mut type_ns_only = false;
 139
 140                 if nested {
 141                     // Correctly handle `self`
 142                     if source.name == keywords::SelfValue.name() {
 143                         type_ns_only = true;
 144
 145                         let last_segment = *module_path.last().unwrap();
 146                         if last_segment.name == keywords::CrateRoot.name() {
 147                             resolve_error(
 148                                 self,
 149                                 use_tree.span,
 150                                 ResolutionError::
 151                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 152                             );
 153                             return;
 154                         }
 155
 156                         // Replace `use foo::self;` with `use foo;`
 157                         let _ = module_path.pop();
 158                         source = last_segment;
 159                         if rename.is_none() {
 160                             ident = last_segment;
 161                         }
 162                     }
 163                 } else {
 164                     // Disallow `self`
 165                     if source.name == keywords::SelfValue.name() {
 166                         resolve_error(self,
 167                                       use_tree.span,
 168                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 169                     }
 170
 171                     // Disallow `use $crate;`
 172                     if source.name == keywords::DollarCrate.name() && path.segments.len() == 1 {
 173                         let crate_root = self.resolve_crate_root(source);
 174                         let crate_name = match crate_root.kind {
 175                             ModuleKind::Def(_, name) => name,
 176                             ModuleKind::Block(..) => unreachable!(),
 177                         };
 178                         source.name = crate_name;
 179                         if rename.is_none() {
 180                             ident.name = crate_name;
 181                         }
 182
 183                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 184                             .note("`use $crate;` was erroneously allowed and \
 185                                    will become a hard error in a future release")
 186                             .emit();
 187                     }
 188                 }
 189
 190                 let subclass = SingleImport {
 191                     target: ident,
 192                     source,
 193                     result: PerNS {
 194                         type_ns: Cell::new(Err(Undetermined)),
 195                         value_ns: Cell::new(Err(Undetermined)),
 196                         macro_ns: Cell::new(Err(Undetermined)),
 197                     },
 198                     type_ns_only,
 199                 };
 200                 self.add_import_directive(
 201                     module_path,
 202                     subclass,
 203                     use_tree.span,
 204                     id,
 205                     root_use_tree.span,
 206                     root_id,
 207                     vis,
 208                     expansion,
 209                 );
 210             }
 211             ast::UseTreeKind::Glob => {
 212                 let subclass = GlobImport {
 213                     is_prelude,
 214                     max_vis: Cell::new(ty::Visibility::Invisible),
 215                 };
 216                 self.add_import_directive(
 217                     module_path,
 218                     subclass,
 219                     use_tree.span,
 220                     id,
 221                     root_use_tree.span,
 222                     root_id,
 223                     vis,
 224                     expansion,
 225                 );
 226             }
 227             ast::UseTreeKind::Nested(ref items) => {
 228                 let prefix = ast::Path {
 229                     segments: module_path.into_iter()
 230                         .map(|ident| ast::PathSegment::from_ident(ident))
 231                         .collect(),
 232                     span: path.span,
 233                 };
 234
 235                 // Ensure there is at most one `self` in the list
 236                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 237                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 238                         if use_tree.ident().name == keywords::SelfValue.name() {
 239                             return Some(use_tree.span);
 240                         }
 241                     }
 242
 243                     None
 244                 }).collect::<Vec<_>>();
 245                 if self_spans.len() > 1 {
 246                     let mut e = resolve_struct_error(self,
 247                         self_spans[0],
 248                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 249
 250                     for other_span in self_spans.iter().skip(1) {
 251                         e.span_label(*other_span, "another `self` import appears here");
 252                     }
 253
 254                     e.emit();
 255                 }
 256
 257                 for &(ref tree, id) in items {
 258                     self.build_reduced_graph_for_use_tree(
 259                         root_use_tree, root_id, tree, id, vis, &prefix, true, item, expansion
 260                     );
 261                 }
 262             }
 263         }
 264     }
 265
 266     /// Constructs the reduced graph for one item.
 267     fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
 268         let parent = self.current_module;
 269         let ident = item.ident;
 270         let sp = item.span;
 271         let vis = self.resolve_visibility(&item.vis);
 272
 273         match item.node {
 274             ItemKind::Use(ref use_tree) => {
 275                 // Imports are resolved as global by default, add starting root segment.
 276                 let prefix = ast::Path {
 277                     segments: use_tree.prefix.make_root().into_iter().collect(),
 278                     span: use_tree.span,
 279                 };
 280
 281                 self.build_reduced_graph_for_use_tree(
 282                     use_tree, item.id, use_tree, item.id, vis, &prefix, false, item, expansion,
 283                 );
 284             }
 285
 286             ItemKind::ExternCrate(orig_name) => {
 287                 let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 288                 let module =
 289                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 290                 self.populate_module_if_necessary(module);
 291                 if injected_crate_name().map_or(false, |name| item.ident.name == name) {
 292                     self.injected_crate = Some(module);
 293                 }
 294
 295                 let used = self.process_legacy_macro_imports(item, module, expansion);
 296                 let binding =
 297                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 298                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 299                     root_id: item.id,
 300                     id: item.id,
 301                     parent,
 302                     imported_module: Cell::new(Some(module)),
 303                     subclass: ImportDirectiveSubclass::ExternCrate(orig_name),
 304                     root_span: item.span,
 305                     span: item.span,
 306                     module_path: Vec::new(),
 307                     vis: Cell::new(vis),
 308                     expansion,
 309                     used: Cell::new(used),
 310                 });
 311                 self.potentially_unused_imports.push(directive);
 312                 let imported_binding = self.import(binding, directive);
 313                 self.define(parent, ident, TypeNS, imported_binding);
 314             }
 315
 316             ItemKind::GlobalAsm(..) => {}
 317
 318             ItemKind::Mod(..) if item.ident == keywords::Invalid.ident() => {} // Crate root
 319
 320             ItemKind::Mod(..) => {
 321                 let def_id = self.definitions.local_def_id(item.id);
 322                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 323                 let module = self.arenas.alloc_module(ModuleData {
 324                     no_implicit_prelude: parent.no_implicit_prelude || {
 325                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 326                     },
 327                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 328                 });
 329                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 330                 self.module_map.insert(def_id, module);
 331
 332                 // Descend into the module.
 333                 self.current_module = module;
 334             }
 335
 336             // Handled in `rustc_metadata::{native_libs,link_args}`
 337             ItemKind::ForeignMod(..) => {}
 338
 339             // These items live in the value namespace.
 340             ItemKind::Static(_, m, _) => {
 341                 let mutbl = m == Mutability::Mutable;
 342                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 343                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 344             }
 345             ItemKind::Const(..) => {
 346                 let def = Def::Const(self.definitions.local_def_id(item.id));
 347                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 348             }
 349             ItemKind::Fn(..) => {
 350                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 351                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 352
 353                 // Functions introducing procedural macros reserve a slot
 354                 // in the macro namespace as well (see #52225).
 355                 if attr::contains_name(&item.attrs, "proc_macro") ||
 356                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 357                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 358                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 359                 }
 360                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 361                     if let Some(trait_attr) =
 362                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 363                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 364                             let sp = trait_attr.span;
 365                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 366                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 367                         }
 368                     }
 369                 }
 370             }
 371
 372             // These items live in the type namespace.
 373             ItemKind::Ty(..) => {
 374                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 375                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 376             }
 377
 378             ItemKind::Existential(_, _) => {
 379                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 380                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 381             }
 382
 383             ItemKind::Enum(ref enum_definition, _) => {
 384                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 385                 let module_kind = ModuleKind::Def(def, 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
 393                 for variant in &(*enum_definition).variants {
 394                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 395                 }
 396             }
 397
 398             ItemKind::TraitAlias(..) => {
 399                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 400                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 401             }
 402
 403             // These items live in both the type and value namespaces.
 404             ItemKind::Struct(ref struct_def, _) => {
 405                 // Define a name in the type namespace.
 406                 let def_id = self.definitions.local_def_id(item.id);
 407                 let def = Def::Struct(def_id);
 408                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 409
 410                 let mut ctor_vis = vis;
 411
 412                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 413
 414                 // If the structure is marked as non_exhaustive then lower the visibility
 415                 // to within the crate.
 416                 if has_non_exhaustive && vis == ty::Visibility::Public {
 417                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 418                 }
 419
 420                 // Record field names for error reporting.
 421                 let field_names = struct_def.fields().iter().filter_map(|field| {
 422                     let field_vis = self.resolve_visibility(&field.vis);
 423                     if ctor_vis.is_at_least(field_vis, &*self) {
 424                         ctor_vis = field_vis;
 425                     }
 426                     field.ident.map(|ident| ident.name)
 427                 }).collect();
 428                 let item_def_id = self.definitions.local_def_id(item.id);
 429                 self.insert_field_names(item_def_id, field_names);
 430
 431                 // If this is a tuple or unit struct, define a name
 432                 // in the value namespace as well.
 433                 if !struct_def.is_struct() {
 434                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 435                                                    CtorKind::from_ast(struct_def));
 436                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 437                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 438                 }
 439             }
 440
 441             ItemKind::Union(ref vdata, _) => {
 442                 let def = Def::Union(self.definitions.local_def_id(item.id));
 443                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 444
 445                 // Record field names for error reporting.
 446                 let field_names = vdata.fields().iter().filter_map(|field| {
 447                     self.resolve_visibility(&field.vis);
 448                     field.ident.map(|ident| ident.name)
 449                 }).collect();
 450                 let item_def_id = self.definitions.local_def_id(item.id);
 451                 self.insert_field_names(item_def_id, field_names);
 452             }
 453
 454             ItemKind::Impl(..) => {}
 455
 456             ItemKind::Trait(..) => {
 457                 let def_id = self.definitions.local_def_id(item.id);
 458
 459                 // Add all the items within to a new module.
 460                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 461                 let module = self.new_module(parent,
 462                                              module_kind,
 463                                              parent.normal_ancestor_id,
 464                                              expansion,
 465                                              item.span);
 466                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 467                 self.current_module = module;
 468             }
 469
 470             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 471         }
 472     }
 473
 474     // Constructs the reduced graph for one variant. Variants exist in the
 475     // type and value namespaces.
 476     fn build_reduced_graph_for_variant(&mut self,
 477                                        variant: &Variant,
 478                                        parent: Module<'a>,
 479                                        vis: ty::Visibility,
 480                                        expansion: Mark) {
 481         let ident = variant.node.ident;
 482         let def_id = self.definitions.local_def_id(variant.node.data.id());
 483
 484         // Define a name in the type namespace.
 485         let def = Def::Variant(def_id);
 486         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 487
 488         // Define a constructor name in the value namespace.
 489         // Braced variants, unlike structs, generate unusable names in
 490         // value namespace, they are reserved for possible future use.
 491         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 492         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 493
 494         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 495     }
 496
 497     /// Constructs the reduced graph for one foreign item.
 498     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 499         let (def, ns) = match item.node {
 500             ForeignItemKind::Fn(..) => {
 501                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 502             }
 503             ForeignItemKind::Static(_, m) => {
 504                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 505             }
 506             ForeignItemKind::Ty => {
 507                 (Def::TyForeign(self.definitions.local_def_id(item.id)), TypeNS)
 508             }
 509             ForeignItemKind::Macro(_) => unreachable!(),
 510         };
 511         let parent = self.current_module;
 512         let vis = self.resolve_visibility(&item.vis);
 513         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 514     }
 515
 516     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 517         let parent = self.current_module;
 518         if self.block_needs_anonymous_module(block) {
 519             let module = self.new_module(parent,
 520                                          ModuleKind::Block(block.id),
 521                                          parent.normal_ancestor_id,
 522                                          expansion,
 523                                          block.span);
 524             self.block_map.insert(block.id, module);
 525             self.current_module = module; // Descend into the block.
 526         }
 527     }
 528
 529     /// Builds the reduced graph for a single item in an external crate.
 530     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 531         let Export { ident, def, vis, span, .. } = child;
 532         let def_id = def.def_id();
 533         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 534         match def {
 535             Def::Mod(..) | Def::Enum(..) => {
 536                 let module = self.new_module(parent,
 537                                              ModuleKind::Def(def, ident.name),
 538                                              def_id,
 539                                              expansion,
 540                                              span);
 541                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 542             }
 543             Def::Variant(..) | Def::TyAlias(..) | Def::TyForeign(..) => {
 544                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 545             }
 546             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 547                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 548             }
 549             Def::StructCtor(..) => {
 550                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 551
 552                 if let Some(struct_def_id) =
 553                         self.cstore.def_key(def_id).parent
 554                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 555                     self.struct_constructors.insert(struct_def_id, (def, vis));
 556                 }
 557             }
 558             Def::Trait(..) => {
 559                 let module_kind = ModuleKind::Def(def, ident.name);
 560                 let module = self.new_module(parent,
 561                                              module_kind,
 562                                              parent.normal_ancestor_id,
 563                                              expansion,
 564                                              span);
 565                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 566
 567                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 568                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 569                     self.define(module, child.ident, ns,
 570                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 571
 572                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 573                            .method_has_self_argument {
 574                         self.has_self.insert(child.def.def_id());
 575                     }
 576                 }
 577                 module.populated.set(true);
 578             }
 579             Def::Struct(..) | Def::Union(..) => {
 580                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 581
 582                 // Record field names for error reporting.
 583                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 584                 self.insert_field_names(def_id, field_names);
 585             }
 586             Def::Macro(..) => {
 587                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 588             }
 589             _ => bug!("unexpected definition: {:?}", def)
 590         }
 591     }
 592
 593     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 594         if def_id.krate == LOCAL_CRATE {
 595             return self.module_map[&def_id]
 596         }
 597
 598         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 599         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 600             return module;
 601         }
 602
 603         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 604             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 605         } else {
 606             let def_key = self.cstore.def_key(def_id);
 607             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 608              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 609         };
 610
 611         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 612         let module =
 613             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 614         self.extern_module_map.insert((def_id, macros_only), module);
 615         module
 616     }
 617
 618     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 619         let def_id = self.macro_defs[&expansion];
 620         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 621             self.local_macro_def_scopes[&id]
 622         } else if def_id.krate == BUILTIN_MACROS_CRATE {
 623             self.injected_crate.unwrap_or(self.graph_root)
 624         } else {
 625             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 626             self.get_module(module_def_id)
 627         }
 628     }
 629
 630     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 631         let def_id = match def {
 632             Def::Macro(def_id, ..) => def_id,
 633             Def::NonMacroAttr => return Lrc::new(SyntaxExtension::NonMacroAttr),
 634             _ => panic!("Expected Def::Macro(..) or Def::NonMacroAttr"),
 635         };
 636         if let Some(ext) = self.macro_map.get(&def_id) {
 637             return ext.clone();
 638         }
 639
 640         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 641             LoadedMacro::MacroDef(macro_def) => macro_def,
 642             LoadedMacro::ProcMacro(ext) => return ext,
 643         };
 644
 645         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 646                                                &self.session.features_untracked(),
 647                                                &macro_def,
 648                                                self.cstore.crate_edition_untracked(def_id.krate)));
 649         self.macro_map.insert(def_id, ext.clone());
 650         ext
 651     }
 652
 653     /// Ensures that the reduced graph rooted at the given external module
 654     /// is built, building it if it is not.
 655     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 656         if module.populated.get() { return }
 657         let def_id = module.def_id().unwrap();
 658         for child in self.cstore.item_children_untracked(def_id, self.session) {
 659             self.build_reduced_graph_for_external_crate_def(module, child);
 660         }
 661         module.populated.set(true)
 662     }
 663
 664     fn legacy_import_macro(&mut self,
 665                            name: Name,
 666                            binding: &'a NameBinding<'a>,
 667                            span: Span,
 668                            allow_shadowing: bool) {
 669         if self.macro_prelude.insert(name, binding).is_some() && !allow_shadowing {
 670             let msg = format!("`{}` is already in scope", name);
 671             let note =
 672                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 673             self.session.struct_span_err(span, &msg).note(note).emit();
 674         }
 675     }
 676
 677     // This returns true if we should consider the underlying `extern crate` to be used.
 678     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>, expansion: Mark)
 679                                     -> bool {
 680         let allow_shadowing = expansion == Mark::root();
 681         let legacy_imports = self.legacy_macro_imports(&item.attrs);
 682         let mut used = legacy_imports != LegacyMacroImports::default();
 683
 684         // `#[macro_use]` is only allowed at the crate root.
 685         if self.current_module.parent.is_some() && used {
 686             span_err!(self.session, item.span, E0468,
 687                       "an `extern crate` loading macros must be at the crate root");
 688         } else if !self.use_extern_macros && !used &&
 689                   self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
 690                       .macros_only() {
 691             let msg = "proc macro crates and `#[no_link]` crates have no effect without \
 692                        `#[macro_use]`";
 693             self.session.span_warn(item.span, msg);
 694             used = true; // Avoid the normal unused extern crate warning
 695         }
 696
 697         let (graph_root, arenas) = (self.graph_root, self.arenas);
 698         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 699             root_id: item.id,
 700             id: item.id,
 701             parent: graph_root,
 702             imported_module: Cell::new(Some(module)),
 703             subclass: ImportDirectiveSubclass::MacroUse,
 704             root_span: span,
 705             span,
 706             module_path: Vec::new(),
 707             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 708             expansion,
 709             used: Cell::new(false),
 710         });
 711
 712         if let Some(span) = legacy_imports.import_all {
 713             let directive = macro_use_directive(span);
 714             self.potentially_unused_imports.push(directive);
 715             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 716                 let imported_binding = self.import(binding, directive);
 717                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 718             });
 719         } else {
 720             for (name, span) in legacy_imports.imports {
 721                 let ident = Ident::with_empty_ctxt(name);
 722                 let result = self.resolve_ident_in_module(module, ident, MacroNS, false, span);
 723                 if let Ok(binding) = result {
 724                     let directive = macro_use_directive(span);
 725                     self.potentially_unused_imports.push(directive);
 726                     let imported_binding = self.import(binding, directive);
 727                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 728                 } else {
 729                     span_err!(self.session, span, E0469, "imported macro not found");
 730                 }
 731             }
 732         }
 733         used
 734     }
 735
 736     // does this attribute list contain "macro_use"?
 737     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 738         for attr in attrs {
 739             if attr.check_name("macro_escape") {
 740                 let msg = "macro_escape is a deprecated synonym for macro_use";
 741                 let mut err = self.session.struct_span_warn(attr.span, msg);
 742                 if let ast::AttrStyle::Inner = attr.style {
 743                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 744                 } else {
 745                     err.emit();
 746                 }
 747             } else if !attr.check_name("macro_use") {
 748                 continue;
 749             }
 750
 751             if !attr.is_word() {
 752                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 753             }
 754             return true;
 755         }
 756
 757         false
 758     }
 759
 760     fn legacy_macro_imports(&mut self, attrs: &[ast::Attribute]) -> LegacyMacroImports {
 761         let mut imports = LegacyMacroImports::default();
 762         for attr in attrs {
 763             if attr.check_name("macro_use") {
 764                 match attr.meta_item_list() {
 765                     Some(names) => for attr in names {
 766                         if let Some(word) = attr.word() {
 767                             imports.imports.push((word.name(), attr.span()));
 768                         } else {
 769                             span_err!(self.session, attr.span(), E0466, "bad macro import");
 770                         }
 771                     },
 772                     None => imports.import_all = Some(attr.span),
 773                 }
 774             }
 775         }
 776         imports
 777     }
 778 }
 779
 780 pub struct BuildReducedGraphVisitor<'a, 'b: 'a, 'c: 'b> {
 781     pub resolver: &'a mut Resolver<'b, 'c>,
 782     pub legacy_scope: LegacyScope<'b>,
 783     pub expansion: Mark,
 784 }
 785
 786 impl<'a, 'b, 'cl> BuildReducedGraphVisitor<'a, 'b, 'cl> {
 787     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 788         let mark = id.placeholder_to_mark();
 789         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 790         self.resolver.unresolved_invocations_macro_export.insert(mark);
 791         let invocation = self.resolver.invocations[&mark];
 792         invocation.module.set(self.resolver.current_module);
 793         invocation.legacy_scope.set(self.legacy_scope);
 794         invocation
 795     }
 796 }
 797
 798 macro_rules! method {
 799     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 800         fn $visit(&mut self, node: &'a $ty) {
 801             if let $invoc(..) = node.node {
 802                 self.visit_invoc(node.id);
 803             } else {
 804                 visit::$walk(self, node);
 805             }
 806         }
 807     }
 808 }
 809
 810 impl<'a, 'b, 'cl> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b, 'cl> {
 811     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 812     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 813     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 814     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 815
 816     fn visit_item(&mut self, item: &'a Item) {
 817         let macro_use = match item.node {
 818             ItemKind::MacroDef(..) => {
 819                 self.resolver.define_macro(item, self.expansion, &mut self.legacy_scope);
 820                 return
 821             }
 822             ItemKind::Mac(..) => {
 823                 self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
 824                 return
 825             }
 826             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 827             _ => false,
 828         };
 829
 830         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 831         self.resolver.build_reduced_graph_for_item(item, self.expansion);
 832         visit::walk_item(self, item);
 833         self.resolver.current_module = parent;
 834         if !macro_use {
 835             self.legacy_scope = legacy_scope;
 836         }
 837     }
 838
 839     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 840         if let ast::StmtKind::Mac(..) = stmt.node {
 841             self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(stmt.id));
 842         } else {
 843             visit::walk_stmt(self, stmt);
 844         }
 845     }
 846
 847     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 848         if let ForeignItemKind::Macro(_) = foreign_item.node {
 849             self.visit_invoc(foreign_item.id);
 850             return;
 851         }
 852
 853         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 854         visit::walk_foreign_item(self, foreign_item);
 855     }
 856
 857     fn visit_block(&mut self, block: &'a Block) {
 858         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 859         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 860         visit::walk_block(self, block);
 861         self.resolver.current_module = parent;
 862         self.legacy_scope = legacy_scope;
 863     }
 864
 865     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 866         let parent = self.resolver.current_module;
 867
 868         if let TraitItemKind::Macro(_) = item.node {
 869             self.visit_invoc(item.id);
 870             return
 871         }
 872
 873         // Add the item to the trait info.
 874         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 875         let (def, ns) = match item.node {
 876             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 877             TraitItemKind::Method(ref sig, _) => {
 878                 if sig.decl.has_self() {
 879                     self.resolver.has_self.insert(item_def_id);
 880                 }
 881                 (Def::Method(item_def_id), ValueNS)
 882             }
 883             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 884             TraitItemKind::Macro(_) => bug!(),  // handled above
 885         };
 886
 887         let vis = ty::Visibility::Public;
 888         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 889
 890         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 891         visit::walk_trait_item(self, item);
 892         self.resolver.current_module = parent;
 893     }
 894
 895     fn visit_token(&mut self, t: Token) {
 896         if let Token::Interpolated(nt) = t {
 897             match nt.0 {
 898                 token::NtExpr(ref expr) => {
 899                     if let ast::ExprKind::Mac(..) = expr.node {
 900                         self.visit_invoc(expr.id);
 901                     }
 902                 }
 903                 _ => {}
 904             }
 905         }
 906     }
 907 }