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, NodeId};
  36 use syntax::ast::{Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  37 use syntax::codemap::respan;
  38 use syntax::ext::base::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::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     fn build_reduced_graph_for_use_tree(&mut self,
 106                                         use_tree: &ast::UseTree,
 107                                         id: NodeId,
 108                                         vis: ty::Visibility,
 109                                         prefix: &ast::Path,
 110                                         nested: bool,
 111                                         item: &Item,
 112                                         expansion: Mark) {
 113         let is_prelude = attr::contains_name(&item.attrs, "prelude_import");
 114         let path = &use_tree.prefix;
 115
 116         let mut module_path: Vec<_> = prefix.segments.iter()
 117             .chain(path.segments.iter())
 118             .map(|seg| respan(seg.span, seg.identifier))
 119             .collect();
 120
 121         match use_tree.kind {
 122             ast::UseTreeKind::Simple(mut ident) => {
 123                 let mut source = module_path.pop().unwrap().node;
 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.node.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.node;
 145                         if ident.name == keywords::SelfValue.name() {
 146                             ident = last_segment.node;
 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 $crate;`
 158                     if source.name == keywords::DollarCrate.name() && path.segments.len() == 1 {
 159                         let crate_root = self.resolve_crate_root(source.ctxt, true);
 160                         let crate_name = match crate_root.kind {
 161                             ModuleKind::Def(_, name) => name,
 162                             ModuleKind::Block(..) => unreachable!(),
 163                         };
 164                         source.name = crate_name;
 165                         if ident.name == keywords::DollarCrate.name() {
 166                             ident.name = crate_name;
 167                         }
 168
 169                         self.session.struct_span_warn(item.span, "`$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: self.per_ns(|_, _| Cell::new(Err(Undetermined))),
 180                     type_ns_only,
 181                 };
 182                 self.add_import_directive(
 183                     module_path, subclass, use_tree.span, id, vis, expansion,
 184                 );
 185             }
 186             ast::UseTreeKind::Glob => {
 187                 let subclass = GlobImport {
 188                     is_prelude,
 189                     max_vis: Cell::new(ty::Visibility::Invisible),
 190                 };
 191                 self.add_import_directive(
 192                     module_path, subclass, use_tree.span, id, vis, expansion,
 193                 );
 194             }
 195             ast::UseTreeKind::Nested(ref items) => {
 196                 let prefix = ast::Path {
 197                     segments: module_path.iter()
 198                         .map(|s| ast::PathSegment {
 199                             identifier: s.node,
 200                             span: s.span,
 201                             parameters: None,
 202                         })
 203                         .collect(),
 204                     span: path.span,
 205                 };
 206
 207                 // Ensure there is at most one `self` in the list
 208                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 209                     if let ast::UseTreeKind::Simple(ident) = use_tree.kind {
 210                         if ident.name == keywords::SelfValue.name() {
 211                             return Some(use_tree.span);
 212                         }
 213                     }
 214
 215                     None
 216                 }).collect::<Vec<_>>();
 217                 if self_spans.len() > 1 {
 218                     let mut e = resolve_struct_error(self,
 219                         self_spans[0],
 220                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 221
 222                     for other_span in self_spans.iter().skip(1) {
 223                         e.span_label(*other_span, "another `self` import appears here");
 224                     }
 225
 226                     e.emit();
 227                 }
 228
 229                 for &(ref tree, id) in items {
 230                     self.build_reduced_graph_for_use_tree(
 231                         tree, id, vis, &prefix, true, item, expansion
 232                     );
 233                 }
 234             }
 235         }
 236     }
 237
 238     /// Constructs the reduced graph for one item.
 239     fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
 240         let parent = self.current_module;
 241         let ident = item.ident;
 242         let sp = item.span;
 243         let vis = self.resolve_visibility(&item.vis);
 244
 245         match item.node {
 246             ItemKind::Use(ref use_tree) => {
 247                 // Just an empty prefix to start out
 248                 let prefix = ast::Path {
 249                     segments: vec![],
 250                     span: use_tree.span,
 251                 };
 252
 253                 self.build_reduced_graph_for_use_tree(
 254                     use_tree, item.id, vis, &prefix, false, item, expansion,
 255                 );
 256             }
 257
 258             ItemKind::ExternCrate(as_name) => {
 259                 self.crate_loader.process_item(item, &self.definitions);
 260
 261                 // n.b. we don't need to look at the path option here, because cstore already did
 262                 let crate_id = self.cstore.extern_mod_stmt_cnum_untracked(item.id).unwrap();
 263                 let module =
 264                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 265                 self.populate_module_if_necessary(module);
 266                 if injected_crate_name().map_or(false, |name| item.ident.name == name) {
 267                     self.injected_crate = Some(module);
 268                 }
 269
 270                 let used = self.process_legacy_macro_imports(item, module, expansion);
 271                 let binding =
 272                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 273                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 274                     id: item.id,
 275                     parent,
 276                     imported_module: Cell::new(Some(module)),
 277                     subclass: ImportDirectiveSubclass::ExternCrate(as_name),
 278                     span: item.span,
 279                     module_path: Vec::new(),
 280                     vis: Cell::new(vis),
 281                     expansion,
 282                     used: Cell::new(used),
 283                 });
 284                 self.potentially_unused_imports.push(directive);
 285                 let imported_binding = self.import(binding, directive);
 286                 self.define(parent, ident, TypeNS, imported_binding);
 287             }
 288
 289             ItemKind::GlobalAsm(..) => {}
 290
 291             ItemKind::Mod(..) if item.ident == keywords::Invalid.ident() => {} // Crate root
 292
 293             ItemKind::Mod(..) => {
 294                 let def_id = self.definitions.local_def_id(item.id);
 295                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 296                 let module = self.arenas.alloc_module(ModuleData {
 297                     no_implicit_prelude: parent.no_implicit_prelude || {
 298                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 299                     },
 300                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 301                 });
 302                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 303                 self.module_map.insert(def_id, module);
 304
 305                 // Descend into the module.
 306                 self.current_module = module;
 307             }
 308
 309             ItemKind::ForeignMod(..) => self.crate_loader.process_item(item, &self.definitions),
 310
 311             // These items live in the value namespace.
 312             ItemKind::Static(_, m, _) => {
 313                 let mutbl = m == Mutability::Mutable;
 314                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 315                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 316             }
 317             ItemKind::Const(..) => {
 318                 let def = Def::Const(self.definitions.local_def_id(item.id));
 319                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 320             }
 321             ItemKind::Fn(..) => {
 322                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 323                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 324             }
 325
 326             // These items live in the type namespace.
 327             ItemKind::Ty(..) => {
 328                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 329                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 330             }
 331
 332             ItemKind::Enum(ref enum_definition, _) => {
 333                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 334                 let module_kind = ModuleKind::Def(def, ident.name);
 335                 let module = self.new_module(parent,
 336                                              module_kind,
 337                                              parent.normal_ancestor_id,
 338                                              expansion,
 339                                              item.span);
 340                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 341
 342                 for variant in &(*enum_definition).variants {
 343                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 344                 }
 345             }
 346
 347             ItemKind::TraitAlias(..) => {
 348                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 349                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 350             }
 351
 352             // These items live in both the type and value namespaces.
 353             ItemKind::Struct(ref struct_def, _) => {
 354                 // Define a name in the type namespace.
 355                 let def_id = self.definitions.local_def_id(item.id);
 356                 let def = Def::Struct(def_id);
 357                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 358
 359                 let mut ctor_vis = vis;
 360
 361                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 362
 363                 // If the structure is marked as non_exhaustive then lower the visibility
 364                 // to within the crate.
 365                 if has_non_exhaustive && vis == ty::Visibility::Public {
 366                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 367                 }
 368
 369                 // Record field names for error reporting.
 370                 let field_names = struct_def.fields().iter().filter_map(|field| {
 371                     let field_vis = self.resolve_visibility(&field.vis);
 372                     if ctor_vis.is_at_least(field_vis, &*self) {
 373                         ctor_vis = field_vis;
 374                     }
 375                     field.ident.map(|ident| ident.name)
 376                 }).collect();
 377                 let item_def_id = self.definitions.local_def_id(item.id);
 378                 self.insert_field_names(item_def_id, field_names);
 379
 380                 // If this is a tuple or unit struct, define a name
 381                 // in the value namespace as well.
 382                 if !struct_def.is_struct() {
 383                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 384                                                    CtorKind::from_ast(struct_def));
 385                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 386                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 387                 }
 388             }
 389
 390             ItemKind::Union(ref vdata, _) => {
 391                 let def = Def::Union(self.definitions.local_def_id(item.id));
 392                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 393
 394                 // Record field names for error reporting.
 395                 let field_names = vdata.fields().iter().filter_map(|field| {
 396                     self.resolve_visibility(&field.vis);
 397                     field.ident.map(|ident| ident.name)
 398                 }).collect();
 399                 let item_def_id = self.definitions.local_def_id(item.id);
 400                 self.insert_field_names(item_def_id, field_names);
 401             }
 402
 403             ItemKind::Impl(..) => {}
 404
 405             ItemKind::Trait(..) => {
 406                 let def_id = self.definitions.local_def_id(item.id);
 407
 408                 // Add all the items within to a new module.
 409                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 410                 let module = self.new_module(parent,
 411                                              module_kind,
 412                                              parent.normal_ancestor_id,
 413                                              expansion,
 414                                              item.span);
 415                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 416                 self.current_module = module;
 417             }
 418
 419             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 420         }
 421     }
 422
 423     // Constructs the reduced graph for one variant. Variants exist in the
 424     // type and value namespaces.
 425     fn build_reduced_graph_for_variant(&mut self,
 426                                        variant: &Variant,
 427                                        parent: Module<'a>,
 428                                        vis: ty::Visibility,
 429                                        expansion: Mark) {
 430         let ident = variant.node.name;
 431         let def_id = self.definitions.local_def_id(variant.node.data.id());
 432
 433         // Define a name in the type namespace.
 434         let def = Def::Variant(def_id);
 435         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 436
 437         // Define a constructor name in the value namespace.
 438         // Braced variants, unlike structs, generate unusable names in
 439         // value namespace, they are reserved for possible future use.
 440         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 441         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 442
 443         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 444     }
 445
 446     /// Constructs the reduced graph for one foreign item.
 447     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 448         let (def, ns) = match item.node {
 449             ForeignItemKind::Fn(..) => {
 450                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 451             }
 452             ForeignItemKind::Static(_, m) => {
 453                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 454             }
 455             ForeignItemKind::Ty => {
 456                 (Def::TyForeign(self.definitions.local_def_id(item.id)), TypeNS)
 457             }
 458         };
 459         let parent = self.current_module;
 460         let vis = self.resolve_visibility(&item.vis);
 461         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 462     }
 463
 464     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 465         let parent = self.current_module;
 466         if self.block_needs_anonymous_module(block) {
 467             let module = self.new_module(parent,
 468                                          ModuleKind::Block(block.id),
 469                                          parent.normal_ancestor_id,
 470                                          expansion,
 471                                          block.span);
 472             self.block_map.insert(block.id, module);
 473             self.current_module = module; // Descend into the block.
 474         }
 475     }
 476
 477     /// Builds the reduced graph for a single item in an external crate.
 478     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 479         let Export { ident, def, vis, span, .. } = child;
 480         let def_id = def.def_id();
 481         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 482         match def {
 483             Def::Mod(..) | Def::Enum(..) => {
 484                 let module = self.new_module(parent,
 485                                              ModuleKind::Def(def, ident.name),
 486                                              def_id,
 487                                              expansion,
 488                                              span);
 489                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 490             }
 491             Def::Variant(..) | Def::TyAlias(..) | Def::TyForeign(..) => {
 492                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 493             }
 494             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 495                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 496             }
 497             Def::StructCtor(..) => {
 498                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 499
 500                 if let Some(struct_def_id) =
 501                         self.cstore.def_key(def_id).parent
 502                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 503                     self.struct_constructors.insert(struct_def_id, (def, vis));
 504                 }
 505             }
 506             Def::Trait(..) => {
 507                 let module_kind = ModuleKind::Def(def, ident.name);
 508                 let module = self.new_module(parent,
 509                                              module_kind,
 510                                              parent.normal_ancestor_id,
 511                                              expansion,
 512                                              span);
 513                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 514
 515                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 516                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 517                     self.define(module, child.ident, ns,
 518                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 519
 520                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 521                            .method_has_self_argument {
 522                         self.has_self.insert(child.def.def_id());
 523                     }
 524                 }
 525                 module.populated.set(true);
 526             }
 527             Def::Struct(..) | Def::Union(..) => {
 528                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 529
 530                 // Record field names for error reporting.
 531                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 532                 self.insert_field_names(def_id, field_names);
 533             }
 534             Def::Macro(..) => {
 535                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 536             }
 537             _ => bug!("unexpected definition: {:?}", def)
 538         }
 539     }
 540
 541     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 542         if def_id.krate == LOCAL_CRATE {
 543             return self.module_map[&def_id]
 544         }
 545
 546         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 547         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 548             return module;
 549         }
 550
 551         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 552             (self.cstore.crate_name_untracked(def_id.krate).as_str(), None)
 553         } else {
 554             let def_key = self.cstore.def_key(def_id);
 555             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 556              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 557         };
 558
 559         let kind = ModuleKind::Def(Def::Mod(def_id), Symbol::intern(&name));
 560         let module =
 561             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 562         self.extern_module_map.insert((def_id, macros_only), module);
 563         module
 564     }
 565
 566     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 567         let def_id = self.macro_defs[&expansion];
 568         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 569             self.local_macro_def_scopes[&id]
 570         } else if def_id.krate == BUILTIN_MACROS_CRATE {
 571             self.injected_crate.unwrap_or(self.graph_root)
 572         } else {
 573             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 574             self.get_module(module_def_id)
 575         }
 576     }
 577
 578     pub fn get_macro(&mut self, def: Def) -> Rc<SyntaxExtension> {
 579         let def_id = match def {
 580             Def::Macro(def_id, ..) => def_id,
 581             _ => panic!("Expected Def::Macro(..)"),
 582         };
 583         if let Some(ext) = self.macro_map.get(&def_id) {
 584             return ext.clone();
 585         }
 586
 587         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 588             LoadedMacro::MacroDef(macro_def) => macro_def,
 589             LoadedMacro::ProcMacro(ext) => return ext,
 590         };
 591
 592         let ext = Rc::new(macro_rules::compile(&self.session.parse_sess,
 593                                                &self.session.features,
 594                                                &macro_def));
 595         self.macro_map.insert(def_id, ext.clone());
 596         ext
 597     }
 598
 599     /// Ensures that the reduced graph rooted at the given external module
 600     /// is built, building it if it is not.
 601     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 602         if module.populated.get() { return }
 603         let def_id = module.def_id().unwrap();
 604         for child in self.cstore.item_children_untracked(def_id, self.session) {
 605             self.build_reduced_graph_for_external_crate_def(module, child);
 606         }
 607         module.populated.set(true)
 608     }
 609
 610     fn legacy_import_macro(&mut self,
 611                            name: Name,
 612                            binding: &'a NameBinding<'a>,
 613                            span: Span,
 614                            allow_shadowing: bool) {
 615         if self.global_macros.insert(name, binding).is_some() && !allow_shadowing {
 616             let msg = format!("`{}` is already in scope", name);
 617             let note =
 618                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 619             self.session.struct_span_err(span, &msg).note(note).emit();
 620         }
 621     }
 622
 623     // This returns true if we should consider the underlying `extern crate` to be used.
 624     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>, expansion: Mark)
 625                                     -> bool {
 626         let allow_shadowing = expansion == Mark::root();
 627         let legacy_imports = self.legacy_macro_imports(&item.attrs);
 628         let mut used = legacy_imports != LegacyMacroImports::default();
 629
 630         // `#[macro_use]` and `#[macro_reexport]` are only allowed at the crate root.
 631         if self.current_module.parent.is_some() && used {
 632             span_err!(self.session, item.span, E0468,
 633                       "an `extern crate` loading macros must be at the crate root");
 634         } else if !self.use_extern_macros && !used &&
 635                   self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
 636                       .macros_only() {
 637             let msg = "proc macro crates and `#[no_link]` crates have no effect without \
 638                        `#[macro_use]`";
 639             self.session.span_warn(item.span, msg);
 640             used = true; // Avoid the normal unused extern crate warning
 641         }
 642
 643         let (graph_root, arenas) = (self.graph_root, self.arenas);
 644         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 645             id: item.id,
 646             parent: graph_root,
 647             imported_module: Cell::new(Some(module)),
 648             subclass: ImportDirectiveSubclass::MacroUse,
 649             span,
 650             module_path: Vec::new(),
 651             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 652             expansion,
 653             used: Cell::new(false),
 654         });
 655
 656         if let Some(span) = legacy_imports.import_all {
 657             let directive = macro_use_directive(span);
 658             self.potentially_unused_imports.push(directive);
 659             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 660                 let imported_binding = self.import(binding, directive);
 661                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 662             });
 663         } else {
 664             for (name, span) in legacy_imports.imports {
 665                 let ident = Ident::with_empty_ctxt(name);
 666                 let result = self.resolve_ident_in_module(module, ident, MacroNS,
 667                                                           false, false, span);
 668                 if let Ok(binding) = result {
 669                     let directive = macro_use_directive(span);
 670                     self.potentially_unused_imports.push(directive);
 671                     let imported_binding = self.import(binding, directive);
 672                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 673                 } else {
 674                     span_err!(self.session, span, E0469, "imported macro not found");
 675                 }
 676             }
 677         }
 678         for (name, span) in legacy_imports.reexports {
 679             self.cstore.export_macros_untracked(module.def_id().unwrap().krate);
 680             let ident = Ident::with_empty_ctxt(name);
 681             let result = self.resolve_ident_in_module(module, ident, MacroNS, false, false, span);
 682             if let Ok(binding) = result {
 683                 let (def, vis) = (binding.def(), binding.vis);
 684                 self.macro_exports.push(Export { ident, def, vis, span, is_import: true });
 685             } else {
 686                 span_err!(self.session, span, E0470, "re-exported macro not found");
 687             }
 688         }
 689         used
 690     }
 691
 692     // does this attribute list contain "macro_use"?
 693     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 694         for attr in attrs {
 695             if attr.check_name("macro_escape") {
 696                 let msg = "macro_escape is a deprecated synonym for macro_use";
 697                 let mut err = self.session.struct_span_warn(attr.span, msg);
 698                 if let ast::AttrStyle::Inner = attr.style {
 699                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 700                 } else {
 701                     err.emit();
 702                 }
 703             } else if !attr.check_name("macro_use") {
 704                 continue;
 705             }
 706
 707             if !attr.is_word() {
 708                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 709             }
 710             return true;
 711         }
 712
 713         false
 714     }
 715
 716     fn legacy_macro_imports(&mut self, attrs: &[ast::Attribute]) -> LegacyMacroImports {
 717         let mut imports = LegacyMacroImports::default();
 718         for attr in attrs {
 719             if attr.check_name("macro_use") {
 720                 match attr.meta_item_list() {
 721                     Some(names) => for attr in names {
 722                         if let Some(word) = attr.word() {
 723                             imports.imports.push((word.name(), attr.span()));
 724                         } else {
 725                             span_err!(self.session, attr.span(), E0466, "bad macro import");
 726                         }
 727                     },
 728                     None => imports.import_all = Some(attr.span),
 729                 }
 730             } else if attr.check_name("macro_reexport") {
 731                 let bad_macro_reexport = |this: &mut Self, span| {
 732                     span_err!(this.session, span, E0467, "bad macro re-export");
 733                 };
 734                 if let Some(names) = attr.meta_item_list() {
 735                     for attr in names {
 736                         if let Some(word) = attr.word() {
 737                             imports.reexports.push((word.name(), attr.span()));
 738                         } else {
 739                             bad_macro_reexport(self, attr.span());
 740                         }
 741                     }
 742                 } else {
 743                     bad_macro_reexport(self, attr.span());
 744                 }
 745             }
 746         }
 747         imports
 748     }
 749 }
 750
 751 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 752     pub resolver: &'a mut Resolver<'b>,
 753     pub legacy_scope: LegacyScope<'b>,
 754     pub expansion: Mark,
 755 }
 756
 757 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 758     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 759         let mark = id.placeholder_to_mark();
 760         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 761         let invocation = self.resolver.invocations[&mark];
 762         invocation.module.set(self.resolver.current_module);
 763         invocation.legacy_scope.set(self.legacy_scope);
 764         invocation
 765     }
 766 }
 767
 768 macro_rules! method {
 769     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 770         fn $visit(&mut self, node: &'a $ty) {
 771             if let $invoc(..) = node.node {
 772                 self.visit_invoc(node.id);
 773             } else {
 774                 visit::$walk(self, node);
 775             }
 776         }
 777     }
 778 }
 779
 780 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 781     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 782     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 783     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 784     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 785
 786     fn visit_item(&mut self, item: &'a Item) {
 787         let macro_use = match item.node {
 788             ItemKind::MacroDef(..) => {
 789                 self.resolver.define_macro(item, self.expansion, &mut self.legacy_scope);
 790                 return
 791             }
 792             ItemKind::Mac(..) => {
 793                 self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
 794                 return
 795             }
 796             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 797             _ => false,
 798         };
 799
 800         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 801         self.resolver.build_reduced_graph_for_item(item, self.expansion);
 802         visit::walk_item(self, item);
 803         self.resolver.current_module = parent;
 804         if !macro_use {
 805             self.legacy_scope = legacy_scope;
 806         }
 807     }
 808
 809     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 810         if let ast::StmtKind::Mac(..) = stmt.node {
 811             self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(stmt.id));
 812         } else {
 813             visit::walk_stmt(self, stmt);
 814         }
 815     }
 816
 817     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 818         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 819         visit::walk_foreign_item(self, foreign_item);
 820     }
 821
 822     fn visit_block(&mut self, block: &'a Block) {
 823         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 824         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 825         visit::walk_block(self, block);
 826         self.resolver.current_module = parent;
 827         self.legacy_scope = legacy_scope;
 828     }
 829
 830     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 831         let parent = self.resolver.current_module;
 832
 833         if let TraitItemKind::Macro(_) = item.node {
 834             self.visit_invoc(item.id);
 835             return
 836         }
 837
 838         // Add the item to the trait info.
 839         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 840         let (def, ns) = match item.node {
 841             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 842             TraitItemKind::Method(ref sig, _) => {
 843                 if sig.decl.has_self() {
 844                     self.resolver.has_self.insert(item_def_id);
 845                 }
 846                 (Def::Method(item_def_id), ValueNS)
 847             }
 848             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 849             TraitItemKind::Macro(_) => bug!(),  // handled above
 850         };
 851
 852         let vis = ty::Visibility::Public;
 853         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 854
 855         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 856         visit::walk_trait_item(self, item);
 857         self.resolver.current_module = parent;
 858     }
 859
 860     fn visit_token(&mut self, t: Token) {
 861         if let Token::Interpolated(nt) = t {
 862             match nt.0 {
 863                 token::NtExpr(ref expr) => {
 864                     if let ast::ExprKind::Mac(..) = expr.node {
 865                         self.visit_invoc(expr.id);
 866                     }
 867                 }
 868                 _ => {}
 869             }
 870         }
 871     }
 872 }