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 {ModuleOrUniformRoot, 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 empty_prefix = module_path.last().map_or(true, |ident| {
 146                             ident.name == keywords::CrateRoot.name()
 147                         });
 148                         if empty_prefix {
 149                             resolve_error(
 150                                 self,
 151                                 use_tree.span,
 152                                 ResolutionError::
 153                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 154                             );
 155                             return;
 156                         }
 157
 158                         // Replace `use foo::self;` with `use foo;`
 159                         source = module_path.pop().unwrap();
 160                         if rename.is_none() {
 161                             ident = source;
 162                         }
 163                     }
 164                 } else {
 165                     // Disallow `self`
 166                     if source.name == keywords::SelfValue.name() {
 167                         resolve_error(self,
 168                                       use_tree.span,
 169                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 170                     }
 171
 172                     // Disallow `use $crate;`
 173                     if source.name == keywords::DollarCrate.name() && module_path.is_empty() {
 174                         let crate_root = self.resolve_crate_root(source);
 175                         let crate_name = match crate_root.kind {
 176                             ModuleKind::Def(_, name) => name,
 177                             ModuleKind::Block(..) => unreachable!(),
 178                         };
 179                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 180                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 181                         // while the current crate doesn't have a valid `crate_name`.
 182                         if crate_name != keywords::Invalid.name() {
 183                             // `crate_name` should not be interpreted as relative.
 184                             module_path.push(Ident {
 185                                 name: keywords::CrateRoot.name(),
 186                                 span: source.span,
 187                             });
 188                             source.name = crate_name;
 189                         }
 190                         if rename.is_none() {
 191                             ident.name = crate_name;
 192                         }
 193
 194                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 195                             .note("`use $crate;` was erroneously allowed and \
 196                                    will become a hard error in a future release")
 197                             .emit();
 198                     }
 199                 }
 200
 201                 if ident.name == keywords::Crate.name() {
 202                     self.session.span_err(ident.span,
 203                         "crate root imports need to be explicitly named: \
 204                          `use crate as name;`");
 205                 }
 206
 207                 let subclass = SingleImport {
 208                     target: ident,
 209                     source,
 210                     result: PerNS {
 211                         type_ns: Cell::new(Err(Undetermined)),
 212                         value_ns: Cell::new(Err(Undetermined)),
 213                         macro_ns: Cell::new(Err(Undetermined)),
 214                     },
 215                     type_ns_only,
 216                 };
 217                 self.add_import_directive(
 218                     module_path,
 219                     subclass,
 220                     use_tree.span,
 221                     id,
 222                     root_use_tree.span,
 223                     root_id,
 224                     vis,
 225                     expansion,
 226                 );
 227             }
 228             ast::UseTreeKind::Glob => {
 229                 let subclass = GlobImport {
 230                     is_prelude,
 231                     max_vis: Cell::new(ty::Visibility::Invisible),
 232                 };
 233                 self.add_import_directive(
 234                     module_path,
 235                     subclass,
 236                     use_tree.span,
 237                     id,
 238                     root_use_tree.span,
 239                     root_id,
 240                     vis,
 241                     expansion,
 242                 );
 243             }
 244             ast::UseTreeKind::Nested(ref items) => {
 245                 let prefix = ast::Path {
 246                     segments: module_path.into_iter()
 247                         .map(|ident| ast::PathSegment::from_ident(ident))
 248                         .collect(),
 249                     span: path.span,
 250                 };
 251
 252                 // Ensure there is at most one `self` in the list
 253                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 254                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 255                         if use_tree.ident().name == keywords::SelfValue.name() {
 256                             return Some(use_tree.span);
 257                         }
 258                     }
 259
 260                     None
 261                 }).collect::<Vec<_>>();
 262                 if self_spans.len() > 1 {
 263                     let mut e = resolve_struct_error(self,
 264                         self_spans[0],
 265                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 266
 267                     for other_span in self_spans.iter().skip(1) {
 268                         e.span_label(*other_span, "another `self` import appears here");
 269                     }
 270
 271                     e.emit();
 272                 }
 273
 274                 for &(ref tree, id) in items {
 275                     self.build_reduced_graph_for_use_tree(
 276                         root_use_tree, root_id, tree, id, vis, &prefix, true, item, expansion
 277                     );
 278                 }
 279             }
 280         }
 281     }
 282
 283     /// Constructs the reduced graph for one item.
 284     fn build_reduced_graph_for_item(&mut self, item: &Item, expansion: Mark) {
 285         let parent = self.current_module;
 286         let ident = item.ident;
 287         let sp = item.span;
 288         let vis = self.resolve_visibility(&item.vis);
 289
 290         match item.node {
 291             ItemKind::Use(ref use_tree) => {
 292                 let uniform_paths =
 293                     self.session.rust_2018() &&
 294                     self.session.features_untracked().uniform_paths;
 295                 // Imports are resolved as global by default, add starting root segment.
 296                 let root = if !uniform_paths {
 297                     use_tree.prefix.make_root()
 298                 } else {
 299                     // Except when `#![feature(uniform_paths)]` is on.
 300                     None
 301                 };
 302                 let prefix = ast::Path {
 303                     segments: root.into_iter().collect(),
 304                     span: use_tree.span,
 305                 };
 306
 307                 self.build_reduced_graph_for_use_tree(
 308                     use_tree, item.id, use_tree, item.id, vis, &prefix, false, item, expansion,
 309                 );
 310             }
 311
 312             ItemKind::ExternCrate(orig_name) => {
 313                 let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 314                 let module =
 315                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 316                 self.populate_module_if_necessary(module);
 317                 if injected_crate_name().map_or(false, |name| item.ident.name == name) {
 318                     self.injected_crate = Some(module);
 319                 }
 320
 321                 let used = self.process_legacy_macro_imports(item, module, expansion);
 322                 let binding =
 323                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 324                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 325                     root_id: item.id,
 326                     id: item.id,
 327                     parent,
 328                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 329                     subclass: ImportDirectiveSubclass::ExternCrate(orig_name),
 330                     root_span: item.span,
 331                     span: item.span,
 332                     module_path: Vec::new(),
 333                     vis: Cell::new(vis),
 334                     expansion,
 335                     used: Cell::new(used),
 336                 });
 337                 self.potentially_unused_imports.push(directive);
 338                 let imported_binding = self.import(binding, directive);
 339                 self.define(parent, ident, TypeNS, imported_binding);
 340             }
 341
 342             ItemKind::GlobalAsm(..) => {}
 343
 344             ItemKind::Mod(..) if item.ident == keywords::Invalid.ident() => {} // Crate root
 345
 346             ItemKind::Mod(..) => {
 347                 let def_id = self.definitions.local_def_id(item.id);
 348                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 349                 let module = self.arenas.alloc_module(ModuleData {
 350                     no_implicit_prelude: parent.no_implicit_prelude || {
 351                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 352                     },
 353                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 354                 });
 355                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 356                 self.module_map.insert(def_id, module);
 357
 358                 // Descend into the module.
 359                 self.current_module = module;
 360             }
 361
 362             // Handled in `rustc_metadata::{native_libs,link_args}`
 363             ItemKind::ForeignMod(..) => {}
 364
 365             // These items live in the value namespace.
 366             ItemKind::Static(_, m, _) => {
 367                 let mutbl = m == Mutability::Mutable;
 368                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 369                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 370             }
 371             ItemKind::Const(..) => {
 372                 let def = Def::Const(self.definitions.local_def_id(item.id));
 373                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 374             }
 375             ItemKind::Fn(..) => {
 376                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 377                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 378
 379                 // Functions introducing procedural macros reserve a slot
 380                 // in the macro namespace as well (see #52225).
 381                 if attr::contains_name(&item.attrs, "proc_macro") ||
 382                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 383                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 384                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 385                 }
 386                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 387                     if let Some(trait_attr) =
 388                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 389                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 390                             let sp = trait_attr.span;
 391                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 392                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 393                         }
 394                     }
 395                 }
 396             }
 397
 398             // These items live in the type namespace.
 399             ItemKind::Ty(..) => {
 400                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 401                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 402             }
 403
 404             ItemKind::Existential(_, _) => {
 405                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 406                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 407             }
 408
 409             ItemKind::Enum(ref enum_definition, _) => {
 410                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 411                 let module_kind = ModuleKind::Def(def, ident.name);
 412                 let module = self.new_module(parent,
 413                                              module_kind,
 414                                              parent.normal_ancestor_id,
 415                                              expansion,
 416                                              item.span);
 417                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 418
 419                 for variant in &(*enum_definition).variants {
 420                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 421                 }
 422             }
 423
 424             ItemKind::TraitAlias(..) => {
 425                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 426                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 427             }
 428
 429             // These items live in both the type and value namespaces.
 430             ItemKind::Struct(ref struct_def, _) => {
 431                 // Define a name in the type namespace.
 432                 let def_id = self.definitions.local_def_id(item.id);
 433                 let def = Def::Struct(def_id);
 434                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 435
 436                 let mut ctor_vis = vis;
 437
 438                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 439
 440                 // If the structure is marked as non_exhaustive then lower the visibility
 441                 // to within the crate.
 442                 if has_non_exhaustive && vis == ty::Visibility::Public {
 443                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 444                 }
 445
 446                 // Record field names for error reporting.
 447                 let field_names = struct_def.fields().iter().filter_map(|field| {
 448                     let field_vis = self.resolve_visibility(&field.vis);
 449                     if ctor_vis.is_at_least(field_vis, &*self) {
 450                         ctor_vis = field_vis;
 451                     }
 452                     field.ident.map(|ident| ident.name)
 453                 }).collect();
 454                 let item_def_id = self.definitions.local_def_id(item.id);
 455                 self.insert_field_names(item_def_id, field_names);
 456
 457                 // If this is a tuple or unit struct, define a name
 458                 // in the value namespace as well.
 459                 if !struct_def.is_struct() {
 460                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 461                                                    CtorKind::from_ast(struct_def));
 462                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 463                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 464                 }
 465             }
 466
 467             ItemKind::Union(ref vdata, _) => {
 468                 let def = Def::Union(self.definitions.local_def_id(item.id));
 469                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 470
 471                 // Record field names for error reporting.
 472                 let field_names = vdata.fields().iter().filter_map(|field| {
 473                     self.resolve_visibility(&field.vis);
 474                     field.ident.map(|ident| ident.name)
 475                 }).collect();
 476                 let item_def_id = self.definitions.local_def_id(item.id);
 477                 self.insert_field_names(item_def_id, field_names);
 478             }
 479
 480             ItemKind::Impl(..) => {}
 481
 482             ItemKind::Trait(..) => {
 483                 let def_id = self.definitions.local_def_id(item.id);
 484
 485                 // Add all the items within to a new module.
 486                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 487                 let module = self.new_module(parent,
 488                                              module_kind,
 489                                              parent.normal_ancestor_id,
 490                                              expansion,
 491                                              item.span);
 492                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 493                 self.current_module = module;
 494             }
 495
 496             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 497         }
 498     }
 499
 500     // Constructs the reduced graph for one variant. Variants exist in the
 501     // type and value namespaces.
 502     fn build_reduced_graph_for_variant(&mut self,
 503                                        variant: &Variant,
 504                                        parent: Module<'a>,
 505                                        vis: ty::Visibility,
 506                                        expansion: Mark) {
 507         let ident = variant.node.ident;
 508         let def_id = self.definitions.local_def_id(variant.node.data.id());
 509
 510         // Define a name in the type namespace.
 511         let def = Def::Variant(def_id);
 512         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 513
 514         // Define a constructor name in the value namespace.
 515         // Braced variants, unlike structs, generate unusable names in
 516         // value namespace, they are reserved for possible future use.
 517         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 518         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 519
 520         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 521     }
 522
 523     /// Constructs the reduced graph for one foreign item.
 524     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 525         let (def, ns) = match item.node {
 526             ForeignItemKind::Fn(..) => {
 527                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 528             }
 529             ForeignItemKind::Static(_, m) => {
 530                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 531             }
 532             ForeignItemKind::Ty => {
 533                 (Def::TyForeign(self.definitions.local_def_id(item.id)), TypeNS)
 534             }
 535             ForeignItemKind::Macro(_) => unreachable!(),
 536         };
 537         let parent = self.current_module;
 538         let vis = self.resolve_visibility(&item.vis);
 539         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 540     }
 541
 542     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 543         let parent = self.current_module;
 544         if self.block_needs_anonymous_module(block) {
 545             let module = self.new_module(parent,
 546                                          ModuleKind::Block(block.id),
 547                                          parent.normal_ancestor_id,
 548                                          expansion,
 549                                          block.span);
 550             self.block_map.insert(block.id, module);
 551             self.current_module = module; // Descend into the block.
 552         }
 553     }
 554
 555     /// Builds the reduced graph for a single item in an external crate.
 556     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 557         let Export { ident, def, vis, span, .. } = child;
 558         let def_id = def.def_id();
 559         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 560         match def {
 561             Def::Mod(..) | Def::Enum(..) => {
 562                 let module = self.new_module(parent,
 563                                              ModuleKind::Def(def, ident.name),
 564                                              def_id,
 565                                              expansion,
 566                                              span);
 567                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 568             }
 569             Def::Variant(..) | Def::TyAlias(..) | Def::TyForeign(..) => {
 570                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 571             }
 572             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 573                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 574             }
 575             Def::StructCtor(..) => {
 576                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 577
 578                 if let Some(struct_def_id) =
 579                         self.cstore.def_key(def_id).parent
 580                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 581                     self.struct_constructors.insert(struct_def_id, (def, vis));
 582                 }
 583             }
 584             Def::Trait(..) => {
 585                 let module_kind = ModuleKind::Def(def, ident.name);
 586                 let module = self.new_module(parent,
 587                                              module_kind,
 588                                              parent.normal_ancestor_id,
 589                                              expansion,
 590                                              span);
 591                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 592
 593                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 594                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 595                     self.define(module, child.ident, ns,
 596                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 597
 598                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 599                            .method_has_self_argument {
 600                         self.has_self.insert(child.def.def_id());
 601                     }
 602                 }
 603                 module.populated.set(true);
 604             }
 605             Def::Struct(..) | Def::Union(..) => {
 606                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 607
 608                 // Record field names for error reporting.
 609                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 610                 self.insert_field_names(def_id, field_names);
 611             }
 612             Def::Macro(..) => {
 613                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 614             }
 615             _ => bug!("unexpected definition: {:?}", def)
 616         }
 617     }
 618
 619     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 620         if def_id.krate == LOCAL_CRATE {
 621             return self.module_map[&def_id]
 622         }
 623
 624         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 625         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 626             return module;
 627         }
 628
 629         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 630             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 631         } else {
 632             let def_key = self.cstore.def_key(def_id);
 633             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 634              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 635         };
 636
 637         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 638         let module =
 639             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 640         self.extern_module_map.insert((def_id, macros_only), module);
 641         module
 642     }
 643
 644     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 645         let def_id = self.macro_defs[&expansion];
 646         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 647             self.local_macro_def_scopes[&id]
 648         } else if def_id.krate == BUILTIN_MACROS_CRATE {
 649             self.injected_crate.unwrap_or(self.graph_root)
 650         } else {
 651             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 652             self.get_module(module_def_id)
 653         }
 654     }
 655
 656     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 657         let def_id = match def {
 658             Def::Macro(def_id, ..) => def_id,
 659             Def::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 660                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 661             }),
 662             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 663         };
 664         if let Some(ext) = self.macro_map.get(&def_id) {
 665             return ext.clone();
 666         }
 667
 668         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 669             LoadedMacro::MacroDef(macro_def) => macro_def,
 670             LoadedMacro::ProcMacro(ext) => return ext,
 671         };
 672
 673         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 674                                                &self.session.features_untracked(),
 675                                                &macro_def,
 676                                                self.cstore.crate_edition_untracked(def_id.krate)));
 677         self.macro_map.insert(def_id, ext.clone());
 678         ext
 679     }
 680
 681     /// Ensures that the reduced graph rooted at the given external module
 682     /// is built, building it if it is not.
 683     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 684         if module.populated.get() { return }
 685         let def_id = module.def_id().unwrap();
 686         for child in self.cstore.item_children_untracked(def_id, self.session) {
 687             self.build_reduced_graph_for_external_crate_def(module, child);
 688         }
 689         module.populated.set(true)
 690     }
 691
 692     fn legacy_import_macro(&mut self,
 693                            name: Name,
 694                            binding: &'a NameBinding<'a>,
 695                            span: Span,
 696                            allow_shadowing: bool) {
 697         if self.macro_prelude.insert(name, binding).is_some() && !allow_shadowing {
 698             let msg = format!("`{}` is already in scope", name);
 699             let note =
 700                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 701             self.session.struct_span_err(span, &msg).note(note).emit();
 702         }
 703     }
 704
 705     // This returns true if we should consider the underlying `extern crate` to be used.
 706     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>, expansion: Mark)
 707                                     -> bool {
 708         let allow_shadowing = expansion == Mark::root();
 709         let legacy_imports = self.legacy_macro_imports(&item.attrs);
 710         let mut used = legacy_imports != LegacyMacroImports::default();
 711
 712         // `#[macro_use]` is only allowed at the crate root.
 713         if self.current_module.parent.is_some() && used {
 714             span_err!(self.session, item.span, E0468,
 715                       "an `extern crate` loading macros must be at the crate root");
 716         } else if !self.use_extern_macros && !used &&
 717                   self.cstore.dep_kind_untracked(module.def_id().unwrap().krate)
 718                       .macros_only() {
 719             let msg = "proc macro crates and `#[no_link]` crates have no effect without \
 720                        `#[macro_use]`";
 721             self.session.span_warn(item.span, msg);
 722             used = true; // Avoid the normal unused extern crate warning
 723         }
 724
 725         let (graph_root, arenas) = (self.graph_root, self.arenas);
 726         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 727             root_id: item.id,
 728             id: item.id,
 729             parent: graph_root,
 730             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 731             subclass: ImportDirectiveSubclass::MacroUse,
 732             root_span: span,
 733             span,
 734             module_path: Vec::new(),
 735             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 736             expansion,
 737             used: Cell::new(false),
 738         });
 739
 740         if let Some(span) = legacy_imports.import_all {
 741             let directive = macro_use_directive(span);
 742             self.potentially_unused_imports.push(directive);
 743             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 744                 let imported_binding = self.import(binding, directive);
 745                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 746             });
 747         } else {
 748             for (name, span) in legacy_imports.imports {
 749                 let ident = Ident::with_empty_ctxt(name);
 750                 let result = self.resolve_ident_in_module(
 751                     ModuleOrUniformRoot::Module(module),
 752                     ident,
 753                     MacroNS,
 754                     false,
 755                     span,
 756                 );
 757                 if let Ok(binding) = result {
 758                     let directive = macro_use_directive(span);
 759                     self.potentially_unused_imports.push(directive);
 760                     let imported_binding = self.import(binding, directive);
 761                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 762                 } else {
 763                     span_err!(self.session, span, E0469, "imported macro not found");
 764                 }
 765             }
 766         }
 767         used
 768     }
 769
 770     // does this attribute list contain "macro_use"?
 771     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 772         for attr in attrs {
 773             if attr.check_name("macro_escape") {
 774                 let msg = "macro_escape is a deprecated synonym for macro_use";
 775                 let mut err = self.session.struct_span_warn(attr.span, msg);
 776                 if let ast::AttrStyle::Inner = attr.style {
 777                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 778                 } else {
 779                     err.emit();
 780                 }
 781             } else if !attr.check_name("macro_use") {
 782                 continue;
 783             }
 784
 785             if !attr.is_word() {
 786                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 787             }
 788             return true;
 789         }
 790
 791         false
 792     }
 793
 794     fn legacy_macro_imports(&mut self, attrs: &[ast::Attribute]) -> LegacyMacroImports {
 795         let mut imports = LegacyMacroImports::default();
 796         for attr in attrs {
 797             if attr.check_name("macro_use") {
 798                 match attr.meta_item_list() {
 799                     Some(names) => for attr in names {
 800                         if let Some(word) = attr.word() {
 801                             imports.imports.push((word.name(), attr.span()));
 802                         } else {
 803                             span_err!(self.session, attr.span(), E0466, "bad macro import");
 804                         }
 805                     },
 806                     None => imports.import_all = Some(attr.span),
 807                 }
 808             }
 809         }
 810         imports
 811     }
 812 }
 813
 814 pub struct BuildReducedGraphVisitor<'a, 'b: 'a, 'c: 'b> {
 815     pub resolver: &'a mut Resolver<'b, 'c>,
 816     pub legacy_scope: LegacyScope<'b>,
 817     pub expansion: Mark,
 818 }
 819
 820 impl<'a, 'b, 'cl> BuildReducedGraphVisitor<'a, 'b, 'cl> {
 821     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 822         let mark = id.placeholder_to_mark();
 823         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 824         let invocation = self.resolver.invocations[&mark];
 825         invocation.module.set(self.resolver.current_module);
 826         invocation.legacy_scope.set(self.legacy_scope);
 827         invocation
 828     }
 829 }
 830
 831 macro_rules! method {
 832     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 833         fn $visit(&mut self, node: &'a $ty) {
 834             if let $invoc(..) = node.node {
 835                 self.visit_invoc(node.id);
 836             } else {
 837                 visit::$walk(self, node);
 838             }
 839         }
 840     }
 841 }
 842
 843 impl<'a, 'b, 'cl> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b, 'cl> {
 844     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 845     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 846     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 847     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 848
 849     fn visit_item(&mut self, item: &'a Item) {
 850         let macro_use = match item.node {
 851             ItemKind::MacroDef(..) => {
 852                 self.resolver.define_macro(item, self.expansion, &mut self.legacy_scope);
 853                 return
 854             }
 855             ItemKind::Mac(..) => {
 856                 self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(item.id));
 857                 return
 858             }
 859             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 860             _ => false,
 861         };
 862
 863         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 864         self.resolver.build_reduced_graph_for_item(item, self.expansion);
 865         visit::walk_item(self, item);
 866         self.resolver.current_module = parent;
 867         if !macro_use {
 868             self.legacy_scope = legacy_scope;
 869         }
 870     }
 871
 872     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 873         if let ast::StmtKind::Mac(..) = stmt.node {
 874             self.legacy_scope = LegacyScope::Expansion(self.visit_invoc(stmt.id));
 875         } else {
 876             visit::walk_stmt(self, stmt);
 877         }
 878     }
 879
 880     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 881         if let ForeignItemKind::Macro(_) = foreign_item.node {
 882             self.visit_invoc(foreign_item.id);
 883             return;
 884         }
 885
 886         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 887         visit::walk_foreign_item(self, foreign_item);
 888     }
 889
 890     fn visit_block(&mut self, block: &'a Block) {
 891         let (parent, legacy_scope) = (self.resolver.current_module, self.legacy_scope);
 892         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 893         visit::walk_block(self, block);
 894         self.resolver.current_module = parent;
 895         self.legacy_scope = legacy_scope;
 896     }
 897
 898     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 899         let parent = self.resolver.current_module;
 900
 901         if let TraitItemKind::Macro(_) = item.node {
 902             self.visit_invoc(item.id);
 903             return
 904         }
 905
 906         // Add the item to the trait info.
 907         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 908         let (def, ns) = match item.node {
 909             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 910             TraitItemKind::Method(ref sig, _) => {
 911                 if sig.decl.has_self() {
 912                     self.resolver.has_self.insert(item_def_id);
 913                 }
 914                 (Def::Method(item_def_id), ValueNS)
 915             }
 916             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 917             TraitItemKind::Macro(_) => bug!(),  // handled above
 918         };
 919
 920         let vis = ty::Visibility::Public;
 921         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 922
 923         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 924         visit::walk_trait_item(self, item);
 925         self.resolver.current_module = parent;
 926     }
 927
 928     fn visit_token(&mut self, t: Token) {
 929         if let Token::Interpolated(nt) = t {
 930             match nt.0 {
 931                 token::NtExpr(ref expr) => {
 932                     if let ast::ExprKind::Mac(..) = expr.node {
 933                         self.visit_invoc(expr.id);
 934                     }
 935                 }
 936                 _ => {}
 937             }
 938         }
 939     }
 940 }