src/librustc_resolve/build_reduced_graph.rs

   1 //! After we obtain a fresh AST fragment from a macro, code in this module helps to integrate
   2 //! that fragment into the module structures that are already partially built.
   3 //!
   4 //! Items from the fragment are placed into modules,
   5 //! unexpanded macros in the fragment are visited and registered.
   6 //! Imports are also considered items and placed into modules here, but not resolved yet.
   7
   8 use crate::def_collector::collect_definitions;
   9 use crate::imports::ImportDirective;
  10 use crate::imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
  11 use crate::macros::{LegacyBinding, LegacyScope};
  12 use crate::Namespace::{self, MacroNS, TypeNS, ValueNS};
  13 use crate::{CrateLint, Determinacy, PathResult, ResolutionError, VisResolutionError};
  14 use crate::{
  15     ExternPreludeEntry, ModuleOrUniformRoot, ParentScope, PerNS, Resolver, ResolverArenas,
  16 };
  17 use crate::{Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, Segment, ToNameBinding};
  18
  19 use rustc::bug;
  20 use rustc::hir::exports::Export;
  21 use rustc::middle::cstore::CrateStore;
  22 use rustc::ty;
  23 use rustc_attr as attr;
  24 use rustc_data_structures::sync::Lrc;
  25 use rustc_errors::{struct_span_err, Applicability};
  26 use rustc_expand::base::SyntaxExtension;
  27 use rustc_expand::expand::AstFragment;
  28 use rustc_hir::def::{self, *};
  29 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
  30 use rustc_metadata::creader::LoadedMacro;
  31 use rustc_span::hygiene::{ExpnId, MacroKind};
  32 use rustc_span::source_map::{respan, Spanned};
  33 use rustc_span::symbol::{kw, sym};
  34 use rustc_span::{Span, DUMMY_SP};
  35 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  36 use syntax::ast::{AssocItem, AssocItemKind, MetaItemKind, StmtKind};
  37 use syntax::ast::{Ident, Name};
  38 use syntax::token::{self, Token};
  39 use syntax::visit::{self, AssocCtxt, Visitor};
  40
  41 use log::debug;
  42 use std::cell::Cell;
  43 use std::ptr;
  44
  45 type Res = def::Res<NodeId>;
  46
  47 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, ExpnId) {
  48     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  49         arenas.alloc_name_binding(NameBinding {
  50             kind: NameBindingKind::Module(self.0),
  51             ambiguity: None,
  52             vis: self.1,
  53             span: self.2,
  54             expansion: self.3,
  55         })
  56     }
  57 }
  58
  59 impl<'a> ToNameBinding<'a> for (Res, ty::Visibility, Span, ExpnId) {
  60     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  61         arenas.alloc_name_binding(NameBinding {
  62             kind: NameBindingKind::Res(self.0, false),
  63             ambiguity: None,
  64             vis: self.1,
  65             span: self.2,
  66             expansion: self.3,
  67         })
  68     }
  69 }
  70
  71 struct IsMacroExport;
  72
  73 impl<'a> ToNameBinding<'a> for (Res, ty::Visibility, Span, ExpnId, IsMacroExport) {
  74     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  75         arenas.alloc_name_binding(NameBinding {
  76             kind: NameBindingKind::Res(self.0, true),
  77             ambiguity: None,
  78             vis: self.1,
  79             span: self.2,
  80             expansion: self.3,
  81         })
  82     }
  83 }
  84
  85 impl<'a> Resolver<'a> {
  86     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  87     /// otherwise, reports an error.
  88     crate fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  89     where
  90         T: ToNameBinding<'a>,
  91     {
  92         let binding = def.to_name_binding(self.arenas);
  93         let key = self.new_key(ident, ns);
  94         if let Err(old_binding) = self.try_define(parent, key, binding) {
  95             self.report_conflict(parent, ident, ns, old_binding, &binding);
  96         }
  97     }
  98
  99     crate fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 100         if def_id.krate == LOCAL_CRATE {
 101             return self.module_map[&def_id];
 102         }
 103
 104         if let Some(&module) = self.extern_module_map.get(&def_id) {
 105             return module;
 106         }
 107
 108         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 109             (self.cstore().crate_name_untracked(def_id.krate), None)
 110         } else {
 111             let def_key = self.cstore().def_key(def_id);
 112             (
 113                 def_key.disambiguated_data.data.get_opt_name().unwrap(),
 114                 Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })),
 115             )
 116         };
 117
 118         let kind = ModuleKind::Def(DefKind::Mod, def_id, name);
 119         let module = self.arenas.alloc_module(ModuleData::new(
 120             parent,
 121             kind,
 122             def_id,
 123             ExpnId::root(),
 124             DUMMY_SP,
 125         ));
 126         self.extern_module_map.insert(def_id, module);
 127         module
 128     }
 129
 130     crate fn macro_def_scope(&mut self, expn_id: ExpnId) -> Module<'a> {
 131         let def_id = match self.macro_defs.get(&expn_id) {
 132             Some(def_id) => *def_id,
 133             None => return self.ast_transform_scopes.get(&expn_id).unwrap_or(&self.graph_root),
 134         };
 135         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 136             self.local_macro_def_scopes[&id]
 137         } else {
 138             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 139             self.get_module(module_def_id)
 140         }
 141     }
 142
 143     crate fn get_macro(&mut self, res: Res) -> Option<Lrc<SyntaxExtension>> {
 144         match res {
 145             Res::Def(DefKind::Macro(..), def_id) => self.get_macro_by_def_id(def_id),
 146             Res::NonMacroAttr(attr_kind) => Some(self.non_macro_attr(attr_kind.is_used())),
 147             _ => None,
 148         }
 149     }
 150
 151     crate fn get_macro_by_def_id(&mut self, def_id: DefId) -> Option<Lrc<SyntaxExtension>> {
 152         if let Some(ext) = self.macro_map.get(&def_id) {
 153             return Some(ext.clone());
 154         }
 155
 156         let ext = Lrc::new(match self.cstore().load_macro_untracked(def_id, &self.session) {
 157             LoadedMacro::MacroDef(item, edition) => self.compile_macro(&item, edition),
 158             LoadedMacro::ProcMacro(ext) => ext,
 159         });
 160
 161         self.macro_map.insert(def_id, ext.clone());
 162         Some(ext)
 163     }
 164
 165     crate fn build_reduced_graph(
 166         &mut self,
 167         fragment: &AstFragment,
 168         parent_scope: ParentScope<'a>,
 169     ) -> LegacyScope<'a> {
 170         collect_definitions(&mut self.definitions, fragment, parent_scope.expansion);
 171         let mut visitor = BuildReducedGraphVisitor { r: self, parent_scope };
 172         fragment.visit_with(&mut visitor);
 173         visitor.parent_scope.legacy
 174     }
 175
 176     crate fn build_reduced_graph_external(&mut self, module: Module<'a>) {
 177         let def_id = module.def_id().expect("unpopulated module without a def-id");
 178         for child in self.cstore().item_children_untracked(def_id, self.session) {
 179             let child = child.map_id(|_| panic!("unexpected id"));
 180             BuildReducedGraphVisitor { r: self, parent_scope: ParentScope::module(module) }
 181                 .build_reduced_graph_for_external_crate_res(child);
 182         }
 183     }
 184 }
 185
 186 struct BuildReducedGraphVisitor<'a, 'b> {
 187     r: &'b mut Resolver<'a>,
 188     parent_scope: ParentScope<'a>,
 189 }
 190
 191 impl<'a> AsMut<Resolver<'a>> for BuildReducedGraphVisitor<'a, '_> {
 192     fn as_mut(&mut self) -> &mut Resolver<'a> {
 193         self.r
 194     }
 195 }
 196
 197 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 198     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
 199         self.resolve_visibility_speculative(vis, false).unwrap_or_else(|err| {
 200             self.r.report_vis_error(err);
 201             ty::Visibility::Public
 202         })
 203     }
 204
 205     fn resolve_visibility_speculative<'ast>(
 206         &mut self,
 207         vis: &'ast ast::Visibility,
 208         speculative: bool,
 209     ) -> Result<ty::Visibility, VisResolutionError<'ast>> {
 210         let parent_scope = &self.parent_scope;
 211         match vis.node {
 212             ast::VisibilityKind::Public => Ok(ty::Visibility::Public),
 213             ast::VisibilityKind::Crate(..) => {
 214                 Ok(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)))
 215             }
 216             ast::VisibilityKind::Inherited => {
 217                 Ok(ty::Visibility::Restricted(parent_scope.module.normal_ancestor_id))
 218             }
 219             ast::VisibilityKind::Restricted { ref path, id, .. } => {
 220                 // For visibilities we are not ready to provide correct implementation of "uniform
 221                 // paths" right now, so on 2018 edition we only allow module-relative paths for now.
 222                 // On 2015 edition visibilities are resolved as crate-relative by default,
 223                 // so we are prepending a root segment if necessary.
 224                 let ident = path.segments.get(0).expect("empty path in visibility").ident;
 225                 let crate_root = if ident.is_path_segment_keyword() {
 226                     None
 227                 } else if ident.span.rust_2015() {
 228                     Some(Segment::from_ident(Ident::new(
 229                         kw::PathRoot,
 230                         path.span.shrink_to_lo().with_ctxt(ident.span.ctxt()),
 231                     )))
 232                 } else {
 233                     return Err(VisResolutionError::Relative2018(ident.span, path));
 234                 };
 235
 236                 let segments = crate_root
 237                     .into_iter()
 238                     .chain(path.segments.iter().map(|seg| seg.into()))
 239                     .collect::<Vec<_>>();
 240                 let expected_found_error = |res| {
 241                     Err(VisResolutionError::ExpectedFound(
 242                         path.span,
 243                         Segment::names_to_string(&segments),
 244                         res,
 245                     ))
 246                 };
 247                 match self.r.resolve_path(
 248                     &segments,
 249                     Some(TypeNS),
 250                     parent_scope,
 251                     !speculative,
 252                     path.span,
 253                     CrateLint::SimplePath(id),
 254                 ) {
 255                     PathResult::Module(ModuleOrUniformRoot::Module(module)) => {
 256                         let res = module.res().expect("visibility resolved to unnamed block");
 257                         if !speculative {
 258                             self.r.record_partial_res(id, PartialRes::new(res));
 259                         }
 260                         if module.is_normal() {
 261                             if res == Res::Err {
 262                                 Ok(ty::Visibility::Public)
 263                             } else {
 264                                 let vis = ty::Visibility::Restricted(res.def_id());
 265                                 if self.r.is_accessible_from(vis, parent_scope.module) {
 266                                     Ok(vis)
 267                                 } else {
 268                                     Err(VisResolutionError::AncestorOnly(path.span))
 269                                 }
 270                             }
 271                         } else {
 272                             expected_found_error(res)
 273                         }
 274                     }
 275                     PathResult::Module(..) => Err(VisResolutionError::ModuleOnly(path.span)),
 276                     PathResult::NonModule(partial_res) => {
 277                         expected_found_error(partial_res.base_res())
 278                     }
 279                     PathResult::Failed { span, label, suggestion, .. } => {
 280                         Err(VisResolutionError::FailedToResolve(span, label, suggestion))
 281                     }
 282                     PathResult::Indeterminate => Err(VisResolutionError::Indeterminate(path.span)),
 283                 }
 284             }
 285         }
 286     }
 287
 288     fn insert_field_names_local(&mut self, def_id: DefId, vdata: &ast::VariantData) {
 289         let field_names = vdata
 290             .fields()
 291             .iter()
 292             .map(|field| respan(field.span, field.ident.map_or(kw::Invalid, |ident| ident.name)))
 293             .collect();
 294         self.insert_field_names(def_id, field_names);
 295     }
 296
 297     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Spanned<Name>>) {
 298         if !field_names.is_empty() {
 299             self.r.field_names.insert(def_id, field_names);
 300         }
 301     }
 302
 303     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 304         // If any statements are items, we need to create an anonymous module
 305         block.stmts.iter().any(|statement| match statement.kind {
 306             StmtKind::Item(_) | StmtKind::Mac(_) => true,
 307             _ => false,
 308         })
 309     }
 310
 311     // Add an import directive to the current module.
 312     fn add_import_directive(
 313         &mut self,
 314         module_path: Vec<Segment>,
 315         subclass: ImportDirectiveSubclass<'a>,
 316         span: Span,
 317         id: NodeId,
 318         item: &ast::Item,
 319         root_span: Span,
 320         root_id: NodeId,
 321         vis: ty::Visibility,
 322     ) {
 323         let current_module = self.parent_scope.module;
 324         let directive = self.r.arenas.alloc_import_directive(ImportDirective {
 325             parent_scope: self.parent_scope,
 326             module_path,
 327             imported_module: Cell::new(None),
 328             subclass,
 329             span,
 330             id,
 331             use_span: item.span,
 332             use_span_with_attributes: item.span_with_attributes(),
 333             has_attributes: !item.attrs.is_empty(),
 334             root_span,
 335             root_id,
 336             vis: Cell::new(vis),
 337             used: Cell::new(false),
 338         });
 339
 340         debug!("add_import_directive({:?})", directive);
 341
 342         self.r.indeterminate_imports.push(directive);
 343         match directive.subclass {
 344             // Don't add unresolved underscore imports to modules
 345             SingleImport { target: Ident { name: kw::Underscore, .. }, .. } => {}
 346             SingleImport { target, type_ns_only, .. } => {
 347                 self.r.per_ns(|this, ns| {
 348                     if !type_ns_only || ns == TypeNS {
 349                         let key = this.new_key(target, ns);
 350                         let mut resolution = this.resolution(current_module, key).borrow_mut();
 351                         resolution.add_single_import(directive);
 352                     }
 353                 });
 354             }
 355             // We don't add prelude imports to the globs since they only affect lexical scopes,
 356             // which are not relevant to import resolution.
 357             GlobImport { is_prelude: true, .. } => {}
 358             GlobImport { .. } => current_module.globs.borrow_mut().push(directive),
 359             _ => unreachable!(),
 360         }
 361     }
 362
 363     fn build_reduced_graph_for_use_tree(
 364         &mut self,
 365         // This particular use tree
 366         use_tree: &ast::UseTree,
 367         id: NodeId,
 368         parent_prefix: &[Segment],
 369         nested: bool,
 370         // The whole `use` item
 371         item: &Item,
 372         vis: ty::Visibility,
 373         root_span: Span,
 374     ) {
 375         debug!(
 376             "build_reduced_graph_for_use_tree(parent_prefix={:?}, use_tree={:?}, nested={})",
 377             parent_prefix, use_tree, nested
 378         );
 379
 380         let mut prefix_iter = parent_prefix
 381             .iter()
 382             .cloned()
 383             .chain(use_tree.prefix.segments.iter().map(|seg| seg.into()))
 384             .peekable();
 385
 386         // On 2015 edition imports are resolved as crate-relative by default,
 387         // so prefixes are prepended with crate root segment if necessary.
 388         // The root is prepended lazily, when the first non-empty prefix or terminating glob
 389         // appears, so imports in braced groups can have roots prepended independently.
 390         let is_glob = if let ast::UseTreeKind::Glob = use_tree.kind { true } else { false };
 391         let crate_root = match prefix_iter.peek() {
 392             Some(seg) if !seg.ident.is_path_segment_keyword() && seg.ident.span.rust_2015() => {
 393                 Some(seg.ident.span.ctxt())
 394             }
 395             None if is_glob && use_tree.span.rust_2015() => Some(use_tree.span.ctxt()),
 396             _ => None,
 397         }
 398         .map(|ctxt| {
 399             Segment::from_ident(Ident::new(
 400                 kw::PathRoot,
 401                 use_tree.prefix.span.shrink_to_lo().with_ctxt(ctxt),
 402             ))
 403         });
 404
 405         let prefix = crate_root.into_iter().chain(prefix_iter).collect::<Vec<_>>();
 406         debug!("build_reduced_graph_for_use_tree: prefix={:?}", prefix);
 407
 408         let empty_for_self = |prefix: &[Segment]| {
 409             prefix.is_empty() || prefix.len() == 1 && prefix[0].ident.name == kw::PathRoot
 410         };
 411         match use_tree.kind {
 412             ast::UseTreeKind::Simple(rename, ..) => {
 413                 let mut ident = use_tree.ident();
 414                 let mut module_path = prefix;
 415                 let mut source = module_path.pop().unwrap();
 416                 let mut type_ns_only = false;
 417
 418                 if nested {
 419                     // Correctly handle `self`
 420                     if source.ident.name == kw::SelfLower {
 421                         type_ns_only = true;
 422
 423                         if empty_for_self(&module_path) {
 424                             self.r.report_error(
 425                                 use_tree.span,
 426                                 ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix,
 427                             );
 428                             return;
 429                         }
 430
 431                         // Replace `use foo::self;` with `use foo;`
 432                         source = module_path.pop().unwrap();
 433                         if rename.is_none() {
 434                             ident = source.ident;
 435                         }
 436                     }
 437                 } else {
 438                     // Disallow `self`
 439                     if source.ident.name == kw::SelfLower {
 440                         self.r.report_error(
 441                             use_tree.span,
 442                             ResolutionError::SelfImportsOnlyAllowedWithin,
 443                         );
 444                     }
 445
 446                     // Disallow `use $crate;`
 447                     if source.ident.name == kw::DollarCrate && module_path.is_empty() {
 448                         let crate_root = self.r.resolve_crate_root(source.ident);
 449                         let crate_name = match crate_root.kind {
 450                             ModuleKind::Def(.., name) => name,
 451                             ModuleKind::Block(..) => unreachable!(),
 452                         };
 453                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 454                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 455                         // while the current crate doesn't have a valid `crate_name`.
 456                         if crate_name != kw::Invalid {
 457                             // `crate_name` should not be interpreted as relative.
 458                             module_path.push(Segment {
 459                                 ident: Ident { name: kw::PathRoot, span: source.ident.span },
 460                                 id: Some(self.r.next_node_id()),
 461                             });
 462                             source.ident.name = crate_name;
 463                         }
 464                         if rename.is_none() {
 465                             ident.name = crate_name;
 466                         }
 467
 468                         self.r
 469                             .session
 470                             .struct_span_err(item.span, "`$crate` may not be imported")
 471                             .emit();
 472                     }
 473                 }
 474
 475                 if ident.name == kw::Crate {
 476                     self.r.session.span_err(
 477                         ident.span,
 478                         "crate root imports need to be explicitly named: \
 479                          `use crate as name;`",
 480                     );
 481                 }
 482
 483                 let subclass = SingleImport {
 484                     source: source.ident,
 485                     target: ident,
 486                     source_bindings: PerNS {
 487                         type_ns: Cell::new(Err(Determinacy::Undetermined)),
 488                         value_ns: Cell::new(Err(Determinacy::Undetermined)),
 489                         macro_ns: Cell::new(Err(Determinacy::Undetermined)),
 490                     },
 491                     target_bindings: PerNS {
 492                         type_ns: Cell::new(None),
 493                         value_ns: Cell::new(None),
 494                         macro_ns: Cell::new(None),
 495                     },
 496                     type_ns_only,
 497                     nested,
 498                 };
 499                 self.add_import_directive(
 500                     module_path,
 501                     subclass,
 502                     use_tree.span,
 503                     id,
 504                     item,
 505                     root_span,
 506                     item.id,
 507                     vis,
 508                 );
 509             }
 510             ast::UseTreeKind::Glob => {
 511                 let subclass = GlobImport {
 512                     is_prelude: attr::contains_name(&item.attrs, sym::prelude_import),
 513                     max_vis: Cell::new(ty::Visibility::Invisible),
 514                 };
 515                 self.add_import_directive(
 516                     prefix,
 517                     subclass,
 518                     use_tree.span,
 519                     id,
 520                     item,
 521                     root_span,
 522                     item.id,
 523                     vis,
 524                 );
 525             }
 526             ast::UseTreeKind::Nested(ref items) => {
 527                 // Ensure there is at most one `self` in the list
 528                 let self_spans = items
 529                     .iter()
 530                     .filter_map(|&(ref use_tree, _)| {
 531                         if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 532                             if use_tree.ident().name == kw::SelfLower {
 533                                 return Some(use_tree.span);
 534                             }
 535                         }
 536
 537                         None
 538                     })
 539                     .collect::<Vec<_>>();
 540                 if self_spans.len() > 1 {
 541                     let mut e = self.r.into_struct_error(
 542                         self_spans[0],
 543                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList,
 544                     );
 545
 546                     for other_span in self_spans.iter().skip(1) {
 547                         e.span_label(*other_span, "another `self` import appears here");
 548                     }
 549
 550                     e.emit();
 551                 }
 552
 553                 for &(ref tree, id) in items {
 554                     self.build_reduced_graph_for_use_tree(
 555                         // This particular use tree
 556                         tree, id, &prefix, true, // The whole `use` item
 557                         item, vis, root_span,
 558                     );
 559                 }
 560
 561                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 562                 // `a::b::c::{self as _}`, so that their prefixes are correctly
 563                 // resolved and checked for privacy/stability/etc.
 564                 if items.is_empty() && !empty_for_self(&prefix) {
 565                     let new_span = prefix[prefix.len() - 1].ident.span;
 566                     let tree = ast::UseTree {
 567                         prefix: ast::Path::from_ident(Ident::new(kw::SelfLower, new_span)),
 568                         kind: ast::UseTreeKind::Simple(
 569                             Some(Ident::new(kw::Underscore, new_span)),
 570                             ast::DUMMY_NODE_ID,
 571                             ast::DUMMY_NODE_ID,
 572                         ),
 573                         span: use_tree.span,
 574                     };
 575                     self.build_reduced_graph_for_use_tree(
 576                         // This particular use tree
 577                         &tree,
 578                         id,
 579                         &prefix,
 580                         true,
 581                         // The whole `use` item
 582                         item,
 583                         ty::Visibility::Invisible,
 584                         root_span,
 585                     );
 586                 }
 587             }
 588         }
 589     }
 590
 591     /// Constructs the reduced graph for one item.
 592     fn build_reduced_graph_for_item(&mut self, item: &'b Item) {
 593         let parent_scope = &self.parent_scope;
 594         let parent = parent_scope.module;
 595         let expansion = parent_scope.expansion;
 596         let ident = item.ident;
 597         let sp = item.span;
 598         let vis = self.resolve_visibility(&item.vis);
 599
 600         match item.kind {
 601             ItemKind::Use(ref use_tree) => {
 602                 self.build_reduced_graph_for_use_tree(
 603                     // This particular use tree
 604                     use_tree,
 605                     item.id,
 606                     &[],
 607                     false,
 608                     // The whole `use` item
 609                     item,
 610                     vis,
 611                     use_tree.span,
 612                 );
 613             }
 614
 615             ItemKind::ExternCrate(orig_name) => {
 616                 let module = if orig_name.is_none() && ident.name == kw::SelfLower {
 617                     self.r
 618                         .session
 619                         .struct_span_err(item.span, "`extern crate self;` requires renaming")
 620                         .span_suggestion(
 621                             item.span,
 622                             "try",
 623                             "extern crate self as name;".into(),
 624                             Applicability::HasPlaceholders,
 625                         )
 626                         .emit();
 627                     return;
 628                 } else if orig_name == Some(kw::SelfLower) {
 629                     self.r.graph_root
 630                 } else {
 631                     let crate_id =
 632                         self.r.crate_loader.process_extern_crate(item, &self.r.definitions);
 633                     self.r.extern_crate_map.insert(item.id, crate_id);
 634                     self.r.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
 635                 };
 636
 637                 let used = self.process_legacy_macro_imports(item, module);
 638                 let binding =
 639                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.r.arenas);
 640                 let directive = self.r.arenas.alloc_import_directive(ImportDirective {
 641                     root_id: item.id,
 642                     id: item.id,
 643                     parent_scope: self.parent_scope,
 644                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 645                     subclass: ImportDirectiveSubclass::ExternCrate {
 646                         source: orig_name,
 647                         target: ident,
 648                     },
 649                     has_attributes: !item.attrs.is_empty(),
 650                     use_span_with_attributes: item.span_with_attributes(),
 651                     use_span: item.span,
 652                     root_span: item.span,
 653                     span: item.span,
 654                     module_path: Vec::new(),
 655                     vis: Cell::new(vis),
 656                     used: Cell::new(used),
 657                 });
 658                 self.r.potentially_unused_imports.push(directive);
 659                 let imported_binding = self.r.import(binding, directive);
 660                 if ptr::eq(parent, self.r.graph_root) {
 661                     if let Some(entry) = self.r.extern_prelude.get(&ident.modern()) {
 662                         if expansion != ExpnId::root()
 663                             && orig_name.is_some()
 664                             && entry.extern_crate_item.is_none()
 665                         {
 666                             let msg = "macro-expanded `extern crate` items cannot \
 667                                        shadow names passed with `--extern`";
 668                             self.r.session.span_err(item.span, msg);
 669                         }
 670                     }
 671                     let entry =
 672                         self.r.extern_prelude.entry(ident.modern()).or_insert(ExternPreludeEntry {
 673                             extern_crate_item: None,
 674                             introduced_by_item: true,
 675                         });
 676                     entry.extern_crate_item = Some(imported_binding);
 677                     if orig_name.is_some() {
 678                         entry.introduced_by_item = true;
 679                     }
 680                 }
 681                 self.r.define(parent, ident, TypeNS, imported_binding);
 682             }
 683
 684             ItemKind::Mod(..) if ident.name == kw::Invalid => {} // Crate root
 685
 686             ItemKind::Mod(..) => {
 687                 let def_id = self.r.definitions.local_def_id(item.id);
 688                 let module_kind = ModuleKind::Def(DefKind::Mod, def_id, ident.name);
 689                 let module = self.r.arenas.alloc_module(ModuleData {
 690                     no_implicit_prelude: parent.no_implicit_prelude || {
 691                         attr::contains_name(&item.attrs, sym::no_implicit_prelude)
 692                     },
 693                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 694                 });
 695                 self.r.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 696                 self.r.module_map.insert(def_id, module);
 697
 698                 // Descend into the module.
 699                 self.parent_scope.module = module;
 700             }
 701
 702             // These items live in the value namespace.
 703             ItemKind::Static(..) => {
 704                 let res = Res::Def(DefKind::Static, self.r.definitions.local_def_id(item.id));
 705                 self.r.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 706             }
 707             ItemKind::Const(..) => {
 708                 let res = Res::Def(DefKind::Const, self.r.definitions.local_def_id(item.id));
 709                 self.r.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 710             }
 711             ItemKind::Fn(..) => {
 712                 let res = Res::Def(DefKind::Fn, self.r.definitions.local_def_id(item.id));
 713                 self.r.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 714
 715                 // Functions introducing procedural macros reserve a slot
 716                 // in the macro namespace as well (see #52225).
 717                 self.define_macro(item);
 718             }
 719
 720             // These items live in the type namespace.
 721             ItemKind::TyAlias(ref ty, _) => {
 722                 let def_kind = match ty.kind.opaque_top_hack() {
 723                     None => DefKind::TyAlias,
 724                     Some(_) => DefKind::OpaqueTy,
 725                 };
 726                 let res = Res::Def(def_kind, self.r.definitions.local_def_id(item.id));
 727                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 728             }
 729
 730             ItemKind::Enum(_, _) => {
 731                 let def_id = self.r.definitions.local_def_id(item.id);
 732                 self.r.variant_vis.insert(def_id, vis);
 733                 let module_kind = ModuleKind::Def(DefKind::Enum, def_id, ident.name);
 734                 let module = self.r.new_module(
 735                     parent,
 736                     module_kind,
 737                     parent.normal_ancestor_id,
 738                     expansion,
 739                     item.span,
 740                 );
 741                 self.r.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 742                 self.parent_scope.module = module;
 743             }
 744
 745             ItemKind::TraitAlias(..) => {
 746                 let res = Res::Def(DefKind::TraitAlias, self.r.definitions.local_def_id(item.id));
 747                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 748             }
 749
 750             // These items live in both the type and value namespaces.
 751             ItemKind::Struct(ref vdata, _) => {
 752                 // Define a name in the type namespace.
 753                 let def_id = self.r.definitions.local_def_id(item.id);
 754                 let res = Res::Def(DefKind::Struct, def_id);
 755                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 756
 757                 // Record field names for error reporting.
 758                 self.insert_field_names_local(def_id, vdata);
 759
 760                 // If this is a tuple or unit struct, define a name
 761                 // in the value namespace as well.
 762                 if let Some(ctor_node_id) = vdata.ctor_id() {
 763                     let mut ctor_vis = vis;
 764                     // If the structure is marked as non_exhaustive then lower the visibility
 765                     // to within the crate.
 766                     if vis == ty::Visibility::Public
 767                         && attr::contains_name(&item.attrs, sym::non_exhaustive)
 768                     {
 769                         ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 770                     }
 771                     for field in vdata.fields() {
 772                         // NOTE: The field may be an expansion placeholder, but expansion sets
 773                         // correct visibilities for unnamed field placeholders specifically, so the
 774                         // constructor visibility should still be determined correctly.
 775                         if let Ok(field_vis) = self.resolve_visibility_speculative(&field.vis, true)
 776                         {
 777                             if ctor_vis.is_at_least(field_vis, &*self.r) {
 778                                 ctor_vis = field_vis;
 779                             }
 780                         }
 781                     }
 782                     let ctor_res = Res::Def(
 783                         DefKind::Ctor(CtorOf::Struct, CtorKind::from_ast(vdata)),
 784                         self.r.definitions.local_def_id(ctor_node_id),
 785                     );
 786                     self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, sp, expansion));
 787                     self.r.struct_constructors.insert(def_id, (ctor_res, ctor_vis));
 788                 }
 789             }
 790
 791             ItemKind::Union(ref vdata, _) => {
 792                 let def_id = self.r.definitions.local_def_id(item.id);
 793                 let res = Res::Def(DefKind::Union, def_id);
 794                 self.r.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 795
 796                 // Record field names for error reporting.
 797                 self.insert_field_names_local(def_id, vdata);
 798             }
 799
 800             ItemKind::Trait(..) => {
 801                 let def_id = self.r.definitions.local_def_id(item.id);
 802
 803                 // Add all the items within to a new module.
 804                 let module_kind = ModuleKind::Def(DefKind::Trait, def_id, ident.name);
 805                 let module = self.r.new_module(
 806                     parent,
 807                     module_kind,
 808                     parent.normal_ancestor_id,
 809                     expansion,
 810                     item.span,
 811                 );
 812                 self.r.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 813                 self.parent_scope.module = module;
 814             }
 815
 816             // These items do not add names to modules.
 817             ItemKind::Impl { .. } | ItemKind::ForeignMod(..) | ItemKind::GlobalAsm(..) => {}
 818
 819             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 820         }
 821     }
 822
 823     /// Constructs the reduced graph for one foreign item.
 824     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem) {
 825         let (res, ns) = match item.kind {
 826             ForeignItemKind::Fn(..) => {
 827                 (Res::Def(DefKind::Fn, self.r.definitions.local_def_id(item.id)), ValueNS)
 828             }
 829             ForeignItemKind::Static(..) => {
 830                 (Res::Def(DefKind::Static, self.r.definitions.local_def_id(item.id)), ValueNS)
 831             }
 832             ForeignItemKind::Ty => {
 833                 (Res::Def(DefKind::ForeignTy, self.r.definitions.local_def_id(item.id)), TypeNS)
 834             }
 835             ForeignItemKind::Macro(_) => unreachable!(),
 836         };
 837         let parent = self.parent_scope.module;
 838         let expansion = self.parent_scope.expansion;
 839         let vis = self.resolve_visibility(&item.vis);
 840         self.r.define(parent, item.ident, ns, (res, vis, item.span, expansion));
 841     }
 842
 843     fn build_reduced_graph_for_block(&mut self, block: &Block) {
 844         let parent = self.parent_scope.module;
 845         let expansion = self.parent_scope.expansion;
 846         if self.block_needs_anonymous_module(block) {
 847             let module = self.r.new_module(
 848                 parent,
 849                 ModuleKind::Block(block.id),
 850                 parent.normal_ancestor_id,
 851                 expansion,
 852                 block.span,
 853             );
 854             self.r.block_map.insert(block.id, module);
 855             self.parent_scope.module = module; // Descend into the block.
 856         }
 857     }
 858
 859     /// Builds the reduced graph for a single item in an external crate.
 860     fn build_reduced_graph_for_external_crate_res(&mut self, child: Export<NodeId>) {
 861         let parent = self.parent_scope.module;
 862         let Export { ident, res, vis, span } = child;
 863         let expansion = ExpnId::root(); // FIXME(jseyfried) intercrate hygiene
 864         // Record primary definitions.
 865         match res {
 866             Res::Def(kind @ DefKind::Mod, def_id)
 867             | Res::Def(kind @ DefKind::Enum, def_id)
 868             | Res::Def(kind @ DefKind::Trait, def_id) => {
 869                 let module = self.r.new_module(
 870                     parent,
 871                     ModuleKind::Def(kind, def_id, ident.name),
 872                     def_id,
 873                     expansion,
 874                     span,
 875                 );
 876                 self.r.define(parent, ident, TypeNS, (module, vis, span, expansion));
 877             }
 878             Res::Def(DefKind::Struct, _)
 879             | Res::Def(DefKind::Union, _)
 880             | Res::Def(DefKind::Variant, _)
 881             | Res::Def(DefKind::TyAlias, _)
 882             | Res::Def(DefKind::ForeignTy, _)
 883             | Res::Def(DefKind::OpaqueTy, _)
 884             | Res::Def(DefKind::TraitAlias, _)
 885             | Res::Def(DefKind::AssocTy, _)
 886             | Res::Def(DefKind::AssocOpaqueTy, _)
 887             | Res::PrimTy(..)
 888             | Res::ToolMod => self.r.define(parent, ident, TypeNS, (res, vis, span, expansion)),
 889             Res::Def(DefKind::Fn, _)
 890             | Res::Def(DefKind::Method, _)
 891             | Res::Def(DefKind::Static, _)
 892             | Res::Def(DefKind::Const, _)
 893             | Res::Def(DefKind::AssocConst, _)
 894             | Res::Def(DefKind::Ctor(..), _) => {
 895                 self.r.define(parent, ident, ValueNS, (res, vis, span, expansion))
 896             }
 897             Res::Def(DefKind::Macro(..), _) | Res::NonMacroAttr(..) => {
 898                 self.r.define(parent, ident, MacroNS, (res, vis, span, expansion))
 899             }
 900             Res::Def(DefKind::TyParam, _)
 901             | Res::Def(DefKind::ConstParam, _)
 902             | Res::Local(..)
 903             | Res::SelfTy(..)
 904             | Res::SelfCtor(..)
 905             | Res::Err => bug!("unexpected resolution: {:?}", res),
 906         }
 907         // Record some extra data for better diagnostics.
 908         let cstore = self.r.cstore();
 909         match res {
 910             Res::Def(DefKind::Struct, def_id) | Res::Def(DefKind::Union, def_id) => {
 911                 let field_names = cstore.struct_field_names_untracked(def_id, self.r.session);
 912                 self.insert_field_names(def_id, field_names);
 913             }
 914             Res::Def(DefKind::Method, def_id) => {
 915                 if cstore.associated_item_cloned_untracked(def_id).method_has_self_argument {
 916                     self.r.has_self.insert(def_id);
 917                 }
 918             }
 919             Res::Def(DefKind::Ctor(CtorOf::Struct, ..), def_id) => {
 920                 let parent = cstore.def_key(def_id).parent;
 921                 if let Some(struct_def_id) = parent.map(|index| DefId { index, ..def_id }) {
 922                     self.r.struct_constructors.insert(struct_def_id, (res, vis));
 923                 }
 924             }
 925             _ => {}
 926         }
 927     }
 928
 929     fn legacy_import_macro(
 930         &mut self,
 931         name: ast::Name,
 932         binding: &'a NameBinding<'a>,
 933         span: Span,
 934         allow_shadowing: bool,
 935     ) {
 936         if self.r.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 937             let msg = format!("`{}` is already in scope", name);
 938             let note =
 939                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 940             self.r.session.struct_span_err(span, &msg).note(note).emit();
 941         }
 942     }
 943
 944     /// Returns `true` if we should consider the underlying `extern crate` to be used.
 945     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>) -> bool {
 946         let mut import_all = None;
 947         let mut single_imports = Vec::new();
 948         for attr in &item.attrs {
 949             if attr.check_name(sym::macro_use) {
 950                 if self.parent_scope.module.parent.is_some() {
 951                     struct_span_err!(
 952                         self.r.session,
 953                         item.span,
 954                         E0468,
 955                         "an `extern crate` loading macros must be at the crate root"
 956                     )
 957                     .emit();
 958                 }
 959                 if let ItemKind::ExternCrate(Some(orig_name)) = item.kind {
 960                     if orig_name == kw::SelfLower {
 961                         self.r
 962                             .session
 963                             .struct_span_err(
 964                                 attr.span,
 965                                 "`#[macro_use]` is not supported on `extern crate self`",
 966                             )
 967                             .emit();
 968                     }
 969                 }
 970                 let ill_formed =
 971                     |span| struct_span_err!(self.r.session, span, E0466, "bad macro import").emit();
 972                 match attr.meta() {
 973                     Some(meta) => match meta.kind {
 974                         MetaItemKind::Word => {
 975                             import_all = Some(meta.span);
 976                             break;
 977                         }
 978                         MetaItemKind::List(nested_metas) => {
 979                             for nested_meta in nested_metas {
 980                                 match nested_meta.ident() {
 981                                     Some(ident) if nested_meta.is_word() => {
 982                                         single_imports.push(ident)
 983                                     }
 984                                     _ => ill_formed(nested_meta.span()),
 985                                 }
 986                             }
 987                         }
 988                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 989                     },
 990                     None => ill_formed(attr.span),
 991                 }
 992             }
 993         }
 994
 995         let macro_use_directive = |this: &Self, span| {
 996             this.r.arenas.alloc_import_directive(ImportDirective {
 997                 root_id: item.id,
 998                 id: item.id,
 999                 parent_scope: this.parent_scope,
1000                 imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
1001                 subclass: ImportDirectiveSubclass::MacroUse,
1002                 use_span_with_attributes: item.span_with_attributes(),
1003                 has_attributes: !item.attrs.is_empty(),
1004                 use_span: item.span,
1005                 root_span: span,
1006                 span,
1007                 module_path: Vec::new(),
1008                 vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
1009                 used: Cell::new(false),
1010             })
1011         };
1012
1013         let allow_shadowing = self.parent_scope.expansion == ExpnId::root();
1014         if let Some(span) = import_all {
1015             let directive = macro_use_directive(self, span);
1016             self.r.potentially_unused_imports.push(directive);
1017             module.for_each_child(self, |this, ident, ns, binding| {
1018                 if ns == MacroNS {
1019                     let imported_binding = this.r.import(binding, directive);
1020                     this.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
1021                 }
1022             });
1023         } else {
1024             for ident in single_imports.iter().cloned() {
1025                 let result = self.r.resolve_ident_in_module(
1026                     ModuleOrUniformRoot::Module(module),
1027                     ident,
1028                     MacroNS,
1029                     &self.parent_scope,
1030                     false,
1031                     ident.span,
1032                 );
1033                 if let Ok(binding) = result {
1034                     let directive = macro_use_directive(self, ident.span);
1035                     self.r.potentially_unused_imports.push(directive);
1036                     let imported_binding = self.r.import(binding, directive);
1037                     self.legacy_import_macro(
1038                         ident.name,
1039                         imported_binding,
1040                         ident.span,
1041                         allow_shadowing,
1042                     );
1043                 } else {
1044                     struct_span_err!(self.r.session, ident.span, E0469, "imported macro not found")
1045                         .emit();
1046                 }
1047             }
1048         }
1049         import_all.is_some() || !single_imports.is_empty()
1050     }
1051
1052     /// Returns `true` if this attribute list contains `macro_use`.
1053     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
1054         for attr in attrs {
1055             if attr.check_name(sym::macro_escape) {
1056                 let msg = "`#[macro_escape]` is a deprecated synonym for `#[macro_use]`";
1057                 let mut err = self.r.session.struct_span_warn(attr.span, msg);
1058                 if let ast::AttrStyle::Inner = attr.style {
1059                     err.help("try an outer attribute: `#[macro_use]`").emit();
1060                 } else {
1061                     err.emit();
1062                 }
1063             } else if !attr.check_name(sym::macro_use) {
1064                 continue;
1065             }
1066
1067             if !attr.is_word() {
1068                 self.r.session.span_err(attr.span, "arguments to `macro_use` are not allowed here");
1069             }
1070             return true;
1071         }
1072
1073         false
1074     }
1075
1076     fn visit_invoc(&mut self, id: NodeId) -> LegacyScope<'a> {
1077         let invoc_id = id.placeholder_to_expn_id();
1078
1079         self.parent_scope.module.unexpanded_invocations.borrow_mut().insert(invoc_id);
1080
1081         let old_parent_scope = self.r.invocation_parent_scopes.insert(invoc_id, self.parent_scope);
1082         assert!(old_parent_scope.is_none(), "invocation data is reset for an invocation");
1083
1084         LegacyScope::Invocation(invoc_id)
1085     }
1086
1087     fn proc_macro_stub(item: &ast::Item) -> Option<(MacroKind, Ident, Span)> {
1088         if attr::contains_name(&item.attrs, sym::proc_macro) {
1089             return Some((MacroKind::Bang, item.ident, item.span));
1090         } else if attr::contains_name(&item.attrs, sym::proc_macro_attribute) {
1091             return Some((MacroKind::Attr, item.ident, item.span));
1092         } else if let Some(attr) = attr::find_by_name(&item.attrs, sym::proc_macro_derive) {
1093             if let Some(nested_meta) = attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
1094                 if let Some(ident) = nested_meta.ident() {
1095                     return Some((MacroKind::Derive, ident, ident.span));
1096                 }
1097             }
1098         }
1099         None
1100     }
1101
1102     // Mark the given macro as unused unless its name starts with `_`.
1103     // Macro uses will remove items from this set, and the remaining
1104     // items will be reported as `unused_macros`.
1105     fn insert_unused_macro(&mut self, ident: Ident, node_id: NodeId, span: Span) {
1106         if !ident.as_str().starts_with("_") {
1107             self.r.unused_macros.insert(node_id, span);
1108         }
1109     }
1110
1111     fn define_macro(&mut self, item: &ast::Item) -> LegacyScope<'a> {
1112         let parent_scope = self.parent_scope;
1113         let expansion = parent_scope.expansion;
1114         let (ext, ident, span, is_legacy) = match &item.kind {
1115             ItemKind::MacroDef(def) => {
1116                 let ext = Lrc::new(self.r.compile_macro(item, self.r.session.edition()));
1117                 (ext, item.ident, item.span, def.legacy)
1118             }
1119             ItemKind::Fn(..) => match Self::proc_macro_stub(item) {
1120                 Some((macro_kind, ident, span)) => {
1121                     self.r.proc_macro_stubs.insert(item.id);
1122                     (self.r.dummy_ext(macro_kind), ident, span, false)
1123                 }
1124                 None => return parent_scope.legacy,
1125             },
1126             _ => unreachable!(),
1127         };
1128
1129         let def_id = self.r.definitions.local_def_id(item.id);
1130         let res = Res::Def(DefKind::Macro(ext.macro_kind()), def_id);
1131         self.r.macro_map.insert(def_id, ext);
1132         self.r.local_macro_def_scopes.insert(item.id, parent_scope.module);
1133
1134         if is_legacy {
1135             let ident = ident.modern();
1136             self.r.macro_names.insert(ident);
1137             let is_macro_export = attr::contains_name(&item.attrs, sym::macro_export);
1138             let vis = if is_macro_export {
1139                 ty::Visibility::Public
1140             } else {
1141                 ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))
1142             };
1143             let binding = (res, vis, span, expansion).to_name_binding(self.r.arenas);
1144             self.r.set_binding_parent_module(binding, parent_scope.module);
1145             self.r.all_macros.insert(ident.name, res);
1146             if is_macro_export {
1147                 let module = self.r.graph_root;
1148                 self.r.define(module, ident, MacroNS, (res, vis, span, expansion, IsMacroExport));
1149             } else {
1150                 self.r.check_reserved_macro_name(ident, res);
1151                 self.insert_unused_macro(ident, item.id, span);
1152             }
1153             LegacyScope::Binding(self.r.arenas.alloc_legacy_binding(LegacyBinding {
1154                 parent_legacy_scope: parent_scope.legacy,
1155                 binding,
1156                 ident,
1157             }))
1158         } else {
1159             let module = parent_scope.module;
1160             let vis = self.resolve_visibility(&item.vis);
1161             if vis != ty::Visibility::Public {
1162                 self.insert_unused_macro(ident, item.id, span);
1163             }
1164             self.r.define(module, ident, MacroNS, (res, vis, span, expansion));
1165             self.parent_scope.legacy
1166         }
1167     }
1168 }
1169
1170 macro_rules! method {
1171     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
1172         fn $visit(&mut self, node: &'b $ty) {
1173             if let $invoc(..) = node.kind {
1174                 self.visit_invoc(node.id);
1175             } else {
1176                 visit::$walk(self, node);
1177             }
1178         }
1179     }
1180 }
1181
1182 impl<'a, 'b> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b> {
1183     method!(visit_expr: ast::Expr, ast::ExprKind::Mac, walk_expr);
1184     method!(visit_pat: ast::Pat, ast::PatKind::Mac, walk_pat);
1185     method!(visit_ty: ast::Ty, ast::TyKind::Mac, walk_ty);
1186
1187     fn visit_item(&mut self, item: &'b Item) {
1188         let macro_use = match item.kind {
1189             ItemKind::MacroDef(..) => {
1190                 self.parent_scope.legacy = self.define_macro(item);
1191                 return;
1192             }
1193             ItemKind::Mac(..) => {
1194                 self.parent_scope.legacy = self.visit_invoc(item.id);
1195                 return;
1196             }
1197             ItemKind::Mod(..) => self.contains_macro_use(&item.attrs),
1198             _ => false,
1199         };
1200         let orig_current_module = self.parent_scope.module;
1201         let orig_current_legacy_scope = self.parent_scope.legacy;
1202         self.build_reduced_graph_for_item(item);
1203         visit::walk_item(self, item);
1204         self.parent_scope.module = orig_current_module;
1205         if !macro_use {
1206             self.parent_scope.legacy = orig_current_legacy_scope;
1207         }
1208     }
1209
1210     fn visit_stmt(&mut self, stmt: &'b ast::Stmt) {
1211         if let ast::StmtKind::Mac(..) = stmt.kind {
1212             self.parent_scope.legacy = self.visit_invoc(stmt.id);
1213         } else {
1214             visit::walk_stmt(self, stmt);
1215         }
1216     }
1217
1218     fn visit_foreign_item(&mut self, foreign_item: &'b ForeignItem) {
1219         if let ForeignItemKind::Macro(_) = foreign_item.kind {
1220             self.visit_invoc(foreign_item.id);
1221             return;
1222         }
1223
1224         self.build_reduced_graph_for_foreign_item(foreign_item);
1225         visit::walk_foreign_item(self, foreign_item);
1226     }
1227
1228     fn visit_block(&mut self, block: &'b Block) {
1229         let orig_current_module = self.parent_scope.module;
1230         let orig_current_legacy_scope = self.parent_scope.legacy;
1231         self.build_reduced_graph_for_block(block);
1232         visit::walk_block(self, block);
1233         self.parent_scope.module = orig_current_module;
1234         self.parent_scope.legacy = orig_current_legacy_scope;
1235     }
1236
1237     fn visit_assoc_item(&mut self, item: &'b AssocItem, ctxt: AssocCtxt) {
1238         let parent = self.parent_scope.module;
1239
1240         if let AssocItemKind::Macro(_) = item.kind {
1241             self.visit_invoc(item.id);
1242             return;
1243         }
1244
1245         if let AssocCtxt::Impl = ctxt {
1246             self.resolve_visibility(&item.vis);
1247             visit::walk_assoc_item(self, item, ctxt);
1248             return;
1249         }
1250
1251         // Add the item to the trait info.
1252         let item_def_id = self.r.definitions.local_def_id(item.id);
1253         let (res, ns) = match item.kind {
1254             AssocItemKind::Const(..) => (Res::Def(DefKind::AssocConst, item_def_id), ValueNS),
1255             AssocItemKind::Fn(ref sig, _, _) => {
1256                 if sig.decl.has_self() {
1257                     self.r.has_self.insert(item_def_id);
1258                 }
1259                 (Res::Def(DefKind::Method, item_def_id), ValueNS)
1260             }
1261             AssocItemKind::TyAlias(..) => (Res::Def(DefKind::AssocTy, item_def_id), TypeNS),
1262             AssocItemKind::Macro(_) => bug!(), // handled above
1263         };
1264
1265         let vis = ty::Visibility::Public;
1266         let expansion = self.parent_scope.expansion;
1267         self.r.define(parent, item.ident, ns, (res, vis, item.span, expansion));
1268
1269         visit::walk_assoc_item(self, item, ctxt);
1270     }
1271
1272     fn visit_token(&mut self, t: Token) {
1273         if let token::Interpolated(nt) = t.kind {
1274             if let token::NtExpr(ref expr) = *nt {
1275                 if let ast::ExprKind::Mac(..) = expr.kind {
1276                     self.visit_invoc(expr.id);
1277                 }
1278             }
1279         }
1280     }
1281
1282     fn visit_attribute(&mut self, attr: &'b ast::Attribute) {
1283         if !attr.is_doc_comment() && attr::is_builtin_attr(attr) {
1284             self.r
1285                 .builtin_attrs
1286                 .push((attr.get_normal_item().path.segments[0].ident, self.parent_scope));
1287         }
1288         visit::walk_attribute(self, attr);
1289     }
1290
1291     fn visit_arm(&mut self, arm: &'b ast::Arm) {
1292         if arm.is_placeholder {
1293             self.visit_invoc(arm.id);
1294         } else {
1295             visit::walk_arm(self, arm);
1296         }
1297     }
1298
1299     fn visit_field(&mut self, f: &'b ast::Field) {
1300         if f.is_placeholder {
1301             self.visit_invoc(f.id);
1302         } else {
1303             visit::walk_field(self, f);
1304         }
1305     }
1306
1307     fn visit_field_pattern(&mut self, fp: &'b ast::FieldPat) {
1308         if fp.is_placeholder {
1309             self.visit_invoc(fp.id);
1310         } else {
1311             visit::walk_field_pattern(self, fp);
1312         }
1313     }
1314
1315     fn visit_generic_param(&mut self, param: &'b ast::GenericParam) {
1316         if param.is_placeholder {
1317             self.visit_invoc(param.id);
1318         } else {
1319             visit::walk_generic_param(self, param);
1320         }
1321     }
1322
1323     fn visit_param(&mut self, p: &'b ast::Param) {
1324         if p.is_placeholder {
1325             self.visit_invoc(p.id);
1326         } else {
1327             visit::walk_param(self, p);
1328         }
1329     }
1330
1331     fn visit_struct_field(&mut self, sf: &'b ast::StructField) {
1332         if sf.is_placeholder {
1333             self.visit_invoc(sf.id);
1334         } else {
1335             self.resolve_visibility(&sf.vis);
1336             visit::walk_struct_field(self, sf);
1337         }
1338     }
1339
1340     // Constructs the reduced graph for one variant. Variants exist in the
1341     // type and value namespaces.
1342     fn visit_variant(&mut self, variant: &'b ast::Variant) {
1343         if variant.is_placeholder {
1344             self.visit_invoc(variant.id);
1345             return;
1346         }
1347
1348         let parent = self.parent_scope.module;
1349         let vis = self.r.variant_vis[&parent.def_id().expect("enum without def-id")];
1350         let expn_id = self.parent_scope.expansion;
1351         let ident = variant.ident;
1352
1353         // Define a name in the type namespace.
1354         let def_id = self.r.definitions.local_def_id(variant.id);
1355         let res = Res::Def(DefKind::Variant, def_id);
1356         self.r.define(parent, ident, TypeNS, (res, vis, variant.span, expn_id));
1357
1358         // If the variant is marked as non_exhaustive then lower the visibility to within the
1359         // crate.
1360         let mut ctor_vis = vis;
1361         let has_non_exhaustive = attr::contains_name(&variant.attrs, sym::non_exhaustive);
1362         if has_non_exhaustive && vis == ty::Visibility::Public {
1363             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
1364         }
1365
1366         // Define a constructor name in the value namespace.
1367         // Braced variants, unlike structs, generate unusable names in
1368         // value namespace, they are reserved for possible future use.
1369         // It's ok to use the variant's id as a ctor id since an
1370         // error will be reported on any use of such resolution anyway.
1371         let ctor_node_id = variant.data.ctor_id().unwrap_or(variant.id);
1372         let ctor_def_id = self.r.definitions.local_def_id(ctor_node_id);
1373         let ctor_kind = CtorKind::from_ast(&variant.data);
1374         let ctor_res = Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
1375         self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, variant.span, expn_id));
1376
1377         visit::walk_variant(self, variant);
1378     }
1379 }