src/librustc_resolve/build_reduced_graph.rs

   1 //! Reduced graph building.
   2 //!
   3 //! Here we build the "reduced graph": the graph of the module tree without
   4 //! any imports resolved.
   5
   6 use crate::macros::{InvocationData, ParentScope, LegacyScope};
   7 use crate::resolve_imports::ImportDirective;
   8 use crate::resolve_imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
   9 use crate::{Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, Segment, ToNameBinding};
  10 use crate::{ModuleOrUniformRoot, PerNS, Resolver, ResolverArenas, ExternPreludeEntry};
  11 use crate::Namespace::{self, TypeNS, ValueNS, MacroNS};
  12 use crate::{resolve_error, resolve_struct_error, ResolutionError};
  13
  14 use rustc::bug;
  15 use rustc::hir::def::{self, *};
  16 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  17 use rustc::ty;
  18 use rustc::middle::cstore::CrateStore;
  19 use rustc_metadata::cstore::LoadedMacro;
  20
  21 use std::cell::Cell;
  22 use std::ptr;
  23 use rustc_data_structures::sync::Lrc;
  24
  25 use errors::Applicability;
  26
  27 use syntax::ast::{Name, Ident};
  28 use syntax::attr;
  29
  30 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  31 use syntax::ast::{MetaItemKind, StmtKind, TraitItem, TraitItemKind, Variant};
  32 use syntax::ext::base::{MacroKind, SyntaxExtension};
  33 use syntax::ext::base::Determinacy::Undetermined;
  34 use syntax::ext::hygiene::Mark;
  35 use syntax::ext::tt::macro_rules;
  36 use syntax::feature_gate::is_builtin_attr;
  37 use syntax::parse::token::{self, Token};
  38 use syntax::span_err;
  39 use syntax::std_inject::injected_crate_name;
  40 use syntax::symbol::{kw, sym};
  41 use syntax::visit::{self, Visitor};
  42
  43 use syntax_pos::{Span, DUMMY_SP};
  44
  45 use log::debug;
  46
  47 type Res = def::Res<NodeId>;
  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             ambiguity: None,
  54             vis: self.1,
  55             span: self.2,
  56             expansion: self.3,
  57         })
  58     }
  59 }
  60
  61 impl<'a> ToNameBinding<'a> for (Res, ty::Visibility, Span, Mark) {
  62     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  63         arenas.alloc_name_binding(NameBinding {
  64             kind: NameBindingKind::Res(self.0, false),
  65             ambiguity: None,
  66             vis: self.1,
  67             span: self.2,
  68             expansion: self.3,
  69         })
  70     }
  71 }
  72
  73 pub(crate) struct IsMacroExport;
  74
  75 impl<'a> ToNameBinding<'a> for (Res, ty::Visibility, Span, Mark, IsMacroExport) {
  76     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  77         arenas.alloc_name_binding(NameBinding {
  78             kind: NameBindingKind::Res(self.0, true),
  79             ambiguity: None,
  80             vis: self.1,
  81             span: self.2,
  82             expansion: self.3,
  83         })
  84     }
  85 }
  86
  87 impl<'a> Resolver<'a> {
  88     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  89     /// otherwise, reports an error.
  90     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  91         where T: ToNameBinding<'a>,
  92     {
  93         let binding = def.to_name_binding(self.arenas);
  94         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  95             self.report_conflict(parent, ident, ns, old_binding, &binding);
  96         }
  97     }
  98
  99     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 100         // If any statements are items, we need to create an anonymous module
 101         block.stmts.iter().any(|statement| match statement.node {
 102             StmtKind::Item(_) | StmtKind::Mac(_) => true,
 103             _ => false,
 104         })
 105     }
 106
 107     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 108         if !field_names.is_empty() {
 109             self.field_names.insert(def_id, field_names);
 110         }
 111     }
 112
 113     fn build_reduced_graph_for_use_tree(
 114         &mut self,
 115         // This particular use tree
 116         use_tree: &ast::UseTree,
 117         id: NodeId,
 118         parent_prefix: &[Segment],
 119         nested: bool,
 120         // The whole `use` item
 121         parent_scope: ParentScope<'a>,
 122         item: &Item,
 123         vis: ty::Visibility,
 124         root_span: Span,
 125     ) {
 126         debug!("build_reduced_graph_for_use_tree(parent_prefix={:?}, use_tree={:?}, nested={})",
 127                parent_prefix, use_tree, nested);
 128
 129         let mut prefix_iter = parent_prefix.iter().cloned()
 130             .chain(use_tree.prefix.segments.iter().map(|seg| seg.into())).peekable();
 131
 132         // On 2015 edition imports are resolved as crate-relative by default,
 133         // so prefixes are prepended with crate root segment if necessary.
 134         // The root is prepended lazily, when the first non-empty prefix or terminating glob
 135         // appears, so imports in braced groups can have roots prepended independently.
 136         let is_glob = if let ast::UseTreeKind::Glob = use_tree.kind { true } else { false };
 137         let crate_root = match prefix_iter.peek() {
 138             Some(seg) if !seg.ident.is_path_segment_keyword() && seg.ident.span.rust_2015() => {
 139                 Some(seg.ident.span.ctxt())
 140             }
 141             None if is_glob && use_tree.span.rust_2015() => {
 142                 Some(use_tree.span.ctxt())
 143             }
 144             _ => None,
 145         }.map(|ctxt| Segment::from_ident(Ident::new(
 146             kw::PathRoot, use_tree.prefix.span.shrink_to_lo().with_ctxt(ctxt)
 147         )));
 148
 149         let prefix = crate_root.into_iter().chain(prefix_iter).collect::<Vec<_>>();
 150         debug!("build_reduced_graph_for_use_tree: prefix={:?}", prefix);
 151
 152         let empty_for_self = |prefix: &[Segment]| {
 153             prefix.is_empty() ||
 154             prefix.len() == 1 && prefix[0].ident.name == kw::PathRoot
 155         };
 156         match use_tree.kind {
 157             ast::UseTreeKind::Simple(rename, ..) => {
 158                 let mut ident = use_tree.ident().gensym_if_underscore();
 159                 let mut module_path = prefix;
 160                 let mut source = module_path.pop().unwrap();
 161                 let mut type_ns_only = false;
 162
 163                 if nested {
 164                     // Correctly handle `self`
 165                     if source.ident.name == kw::SelfLower {
 166                         type_ns_only = true;
 167
 168                         if empty_for_self(&module_path) {
 169                             resolve_error(
 170                                 self,
 171                                 use_tree.span,
 172                                 ResolutionError::
 173                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 174                             );
 175                             return;
 176                         }
 177
 178                         // Replace `use foo::self;` with `use foo;`
 179                         source = module_path.pop().unwrap();
 180                         if rename.is_none() {
 181                             ident = source.ident;
 182                         }
 183                     }
 184                 } else {
 185                     // Disallow `self`
 186                     if source.ident.name == kw::SelfLower {
 187                         resolve_error(self,
 188                                       use_tree.span,
 189                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 190                     }
 191
 192                     // Disallow `use $crate;`
 193                     if source.ident.name == kw::DollarCrate && module_path.is_empty() {
 194                         let crate_root = self.resolve_crate_root(source.ident);
 195                         let crate_name = match crate_root.kind {
 196                             ModuleKind::Def(.., name) => name,
 197                             ModuleKind::Block(..) => unreachable!(),
 198                         };
 199                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 200                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 201                         // while the current crate doesn't have a valid `crate_name`.
 202                         if crate_name != kw::Invalid {
 203                             // `crate_name` should not be interpreted as relative.
 204                             module_path.push(Segment {
 205                                 ident: Ident {
 206                                     name: kw::PathRoot,
 207                                     span: source.ident.span,
 208                                 },
 209                                 id: Some(self.session.next_node_id()),
 210                             });
 211                             source.ident.name = crate_name;
 212                         }
 213                         if rename.is_none() {
 214                             ident.name = crate_name;
 215                         }
 216
 217                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 218                             .note("`use $crate;` was erroneously allowed and \
 219                                    will become a hard error in a future release")
 220                             .emit();
 221                     }
 222                 }
 223
 224                 if ident.name == kw::Crate {
 225                     self.session.span_err(ident.span,
 226                         "crate root imports need to be explicitly named: \
 227                          `use crate as name;`");
 228                 }
 229
 230                 let subclass = SingleImport {
 231                     source: source.ident,
 232                     target: ident,
 233                     source_bindings: PerNS {
 234                         type_ns: Cell::new(Err(Undetermined)),
 235                         value_ns: Cell::new(Err(Undetermined)),
 236                         macro_ns: Cell::new(Err(Undetermined)),
 237                     },
 238                     target_bindings: PerNS {
 239                         type_ns: Cell::new(None),
 240                         value_ns: Cell::new(None),
 241                         macro_ns: Cell::new(None),
 242                     },
 243                     type_ns_only,
 244                     nested,
 245                 };
 246                 self.add_import_directive(
 247                     module_path,
 248                     subclass,
 249                     use_tree.span,
 250                     id,
 251                     item,
 252                     root_span,
 253                     item.id,
 254                     vis,
 255                     parent_scope,
 256                 );
 257             }
 258             ast::UseTreeKind::Glob => {
 259                 let subclass = GlobImport {
 260                     is_prelude: attr::contains_name(&item.attrs, sym::prelude_import),
 261                     max_vis: Cell::new(ty::Visibility::Invisible),
 262                 };
 263                 self.add_import_directive(
 264                     prefix,
 265                     subclass,
 266                     use_tree.span,
 267                     id,
 268                     item,
 269                     root_span,
 270                     item.id,
 271                     vis,
 272                     parent_scope,
 273                 );
 274             }
 275             ast::UseTreeKind::Nested(ref items) => {
 276                 // Ensure there is at most one `self` in the list
 277                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 278                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 279                         if use_tree.ident().name == kw::SelfLower {
 280                             return Some(use_tree.span);
 281                         }
 282                     }
 283
 284                     None
 285                 }).collect::<Vec<_>>();
 286                 if self_spans.len() > 1 {
 287                     let mut e = resolve_struct_error(self,
 288                         self_spans[0],
 289                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 290
 291                     for other_span in self_spans.iter().skip(1) {
 292                         e.span_label(*other_span, "another `self` import appears here");
 293                     }
 294
 295                     e.emit();
 296                 }
 297
 298                 for &(ref tree, id) in items {
 299                     self.build_reduced_graph_for_use_tree(
 300                         // This particular use tree
 301                         tree, id, &prefix, true,
 302                         // The whole `use` item
 303                         parent_scope.clone(), item, vis, root_span,
 304                     );
 305                 }
 306
 307                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 308                 // `a::b::c::{self as __dummy}`, so that their prefixes are correctly
 309                 // resolved and checked for privacy/stability/etc.
 310                 if items.is_empty() && !empty_for_self(&prefix) {
 311                     let new_span = prefix[prefix.len() - 1].ident.span;
 312                     let tree = ast::UseTree {
 313                         prefix: ast::Path::from_ident(
 314                             Ident::new(kw::SelfLower, new_span)
 315                         ),
 316                         kind: ast::UseTreeKind::Simple(
 317                             Some(Ident::from_str_and_span("__dummy", new_span).gensym()),
 318                             ast::DUMMY_NODE_ID,
 319                             ast::DUMMY_NODE_ID,
 320                         ),
 321                         span: use_tree.span,
 322                     };
 323                     self.build_reduced_graph_for_use_tree(
 324                         // This particular use tree
 325                         &tree, id, &prefix, true,
 326                         // The whole `use` item
 327                         parent_scope, item, ty::Visibility::Invisible, root_span,
 328                     );
 329                 }
 330             }
 331         }
 332     }
 333
 334     /// Constructs the reduced graph for one item.
 335     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_scope: ParentScope<'a>) {
 336         let parent = parent_scope.module;
 337         let expansion = parent_scope.expansion;
 338         let ident = item.ident.gensym_if_underscore();
 339         let sp = item.span;
 340         let vis = self.resolve_visibility(&item.vis);
 341
 342         match item.node {
 343             ItemKind::Use(ref use_tree) => {
 344                 self.build_reduced_graph_for_use_tree(
 345                     // This particular use tree
 346                     use_tree, item.id, &[], false,
 347                     // The whole `use` item
 348                     parent_scope, item, vis, use_tree.span,
 349                 );
 350             }
 351
 352             ItemKind::ExternCrate(orig_name) => {
 353                 let module = if orig_name.is_none() && ident.name == kw::SelfLower {
 354                     self.session
 355                         .struct_span_err(item.span, "`extern crate self;` requires renaming")
 356                         .span_suggestion(
 357                             item.span,
 358                             "try",
 359                             "extern crate self as name;".into(),
 360                             Applicability::HasPlaceholders,
 361                         )
 362                         .emit();
 363                     return;
 364                 } else if orig_name == Some(kw::SelfLower) {
 365                     self.graph_root
 366                 } else {
 367                     let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 368                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
 369                 };
 370
 371                 self.populate_module_if_necessary(module);
 372                 if injected_crate_name().map_or(false, |name| ident.name.as_str() == name) {
 373                     self.injected_crate = Some(module);
 374                 }
 375
 376                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
 377                 let binding =
 378                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 379                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 380                     root_id: item.id,
 381                     id: item.id,
 382                     parent_scope,
 383                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 384                     subclass: ImportDirectiveSubclass::ExternCrate {
 385                         source: orig_name,
 386                         target: ident,
 387                     },
 388                     has_attributes: !item.attrs.is_empty(),
 389                     use_span_with_attributes: item.span_with_attributes(),
 390                     use_span: item.span,
 391                     root_span: item.span,
 392                     span: item.span,
 393                     module_path: Vec::new(),
 394                     vis: Cell::new(vis),
 395                     used: Cell::new(used),
 396                 });
 397                 self.potentially_unused_imports.push(directive);
 398                 let imported_binding = self.import(binding, directive);
 399                 if ptr::eq(self.current_module, self.graph_root) {
 400                     if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
 401                         if expansion != Mark::root() && orig_name.is_some() &&
 402                            entry.extern_crate_item.is_none() {
 403                             self.session.span_err(item.span, "macro-expanded `extern crate` items \
 404                                                               cannot shadow names passed with \
 405                                                               `--extern`");
 406                         }
 407                     }
 408                     let entry = self.extern_prelude.entry(ident.modern())
 409                                                    .or_insert(ExternPreludeEntry {
 410                         extern_crate_item: None,
 411                         introduced_by_item: true,
 412                     });
 413                     entry.extern_crate_item = Some(imported_binding);
 414                     if orig_name.is_some() {
 415                         entry.introduced_by_item = true;
 416                     }
 417                 }
 418                 self.define(parent, ident, TypeNS, imported_binding);
 419             }
 420
 421             ItemKind::GlobalAsm(..) => {}
 422
 423             ItemKind::Mod(..) if ident.name == kw::Invalid => {} // Crate root
 424
 425             ItemKind::Mod(..) => {
 426                 let def_id = self.definitions.local_def_id(item.id);
 427                 let module_kind = ModuleKind::Def(DefKind::Mod, def_id, ident.name);
 428                 let module = self.arenas.alloc_module(ModuleData {
 429                     no_implicit_prelude: parent.no_implicit_prelude || {
 430                         attr::contains_name(&item.attrs, sym::no_implicit_prelude)
 431                     },
 432                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 433                 });
 434                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 435                 self.module_map.insert(def_id, module);
 436
 437                 // Descend into the module.
 438                 self.current_module = module;
 439             }
 440
 441             // Handled in `rustc_metadata::{native_libs,link_args}`
 442             ItemKind::ForeignMod(..) => {}
 443
 444             // These items live in the value namespace.
 445             ItemKind::Static(..) => {
 446                 let res = Res::Def(DefKind::Static, self.definitions.local_def_id(item.id));
 447                 self.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 448             }
 449             ItemKind::Const(..) => {
 450                 let res = Res::Def(DefKind::Const, self.definitions.local_def_id(item.id));
 451                 self.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 452             }
 453             ItemKind::Fn(..) => {
 454                 let res = Res::Def(DefKind::Fn, self.definitions.local_def_id(item.id));
 455                 self.define(parent, ident, ValueNS, (res, vis, sp, expansion));
 456
 457                 // Functions introducing procedural macros reserve a slot
 458                 // in the macro namespace as well (see #52225).
 459                 if attr::contains_name(&item.attrs, sym::proc_macro) ||
 460                    attr::contains_name(&item.attrs, sym::proc_macro_attribute) {
 461                     let res = Res::Def(DefKind::Macro(MacroKind::ProcMacroStub), res.def_id());
 462                     self.define(parent, ident, MacroNS, (res, vis, sp, expansion));
 463                 }
 464                 if let Some(attr) = attr::find_by_name(&item.attrs, sym::proc_macro_derive) {
 465                     if let Some(trait_attr) =
 466                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 467                         if let Some(ident) = trait_attr.ident() {
 468                             let res = Res::Def(
 469                                 DefKind::Macro(MacroKind::ProcMacroStub),
 470                                 res.def_id(),
 471                             );
 472                             self.define(parent, ident, MacroNS, (res, vis, ident.span, expansion));
 473                         }
 474                     }
 475                 }
 476             }
 477
 478             // These items live in the type namespace.
 479             ItemKind::Ty(..) => {
 480                 let res = Res::Def(DefKind::TyAlias, self.definitions.local_def_id(item.id));
 481                 self.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 482             }
 483
 484             ItemKind::Existential(_, _) => {
 485                 let res = Res::Def(DefKind::Existential, self.definitions.local_def_id(item.id));
 486                 self.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 487             }
 488
 489             ItemKind::Enum(ref enum_definition, _) => {
 490                 let module_kind = ModuleKind::Def(
 491                     DefKind::Enum,
 492                     self.definitions.local_def_id(item.id),
 493                     ident.name,
 494                 );
 495                 let module = self.new_module(parent,
 496                                              module_kind,
 497                                              parent.normal_ancestor_id,
 498                                              expansion,
 499                                              item.span);
 500                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 501
 502                 for variant in &(*enum_definition).variants {
 503                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 504                 }
 505             }
 506
 507             ItemKind::TraitAlias(..) => {
 508                 let res = Res::Def(DefKind::TraitAlias, self.definitions.local_def_id(item.id));
 509                 self.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 510             }
 511
 512             // These items live in both the type and value namespaces.
 513             ItemKind::Struct(ref struct_def, _) => {
 514                 // Define a name in the type namespace.
 515                 let def_id = self.definitions.local_def_id(item.id);
 516                 let res = Res::Def(DefKind::Struct, def_id);
 517                 self.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 518
 519                 let mut ctor_vis = vis;
 520
 521                 let has_non_exhaustive = attr::contains_name(&item.attrs, sym::non_exhaustive);
 522
 523                 // If the structure is marked as non_exhaustive then lower the visibility
 524                 // to within the crate.
 525                 if has_non_exhaustive && vis == ty::Visibility::Public {
 526                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 527                 }
 528
 529                 // Record field names for error reporting.
 530                 let field_names = struct_def.fields().iter().filter_map(|field| {
 531                     let field_vis = self.resolve_visibility(&field.vis);
 532                     if ctor_vis.is_at_least(field_vis, &*self) {
 533                         ctor_vis = field_vis;
 534                     }
 535                     field.ident.map(|ident| ident.name)
 536                 }).collect();
 537                 let item_def_id = self.definitions.local_def_id(item.id);
 538                 self.insert_field_names(item_def_id, field_names);
 539
 540                 // If this is a tuple or unit struct, define a name
 541                 // in the value namespace as well.
 542                 if let Some(ctor_node_id) = struct_def.ctor_id() {
 543                     let ctor_res = Res::Def(
 544                         DefKind::Ctor(CtorOf::Struct, CtorKind::from_ast(struct_def)),
 545                         self.definitions.local_def_id(ctor_node_id),
 546                     );
 547                     self.define(parent, ident, ValueNS, (ctor_res, ctor_vis, sp, expansion));
 548                     self.struct_constructors.insert(res.def_id(), (ctor_res, ctor_vis));
 549                 }
 550             }
 551
 552             ItemKind::Union(ref vdata, _) => {
 553                 let res = Res::Def(DefKind::Union, self.definitions.local_def_id(item.id));
 554                 self.define(parent, ident, TypeNS, (res, vis, sp, expansion));
 555
 556                 // Record field names for error reporting.
 557                 let field_names = vdata.fields().iter().filter_map(|field| {
 558                     self.resolve_visibility(&field.vis);
 559                     field.ident.map(|ident| ident.name)
 560                 }).collect();
 561                 let item_def_id = self.definitions.local_def_id(item.id);
 562                 self.insert_field_names(item_def_id, field_names);
 563             }
 564
 565             ItemKind::Impl(..) => {}
 566
 567             ItemKind::Trait(..) => {
 568                 let def_id = self.definitions.local_def_id(item.id);
 569
 570                 // Add all the items within to a new module.
 571                 let module_kind = ModuleKind::Def(DefKind::Trait, def_id, ident.name);
 572                 let module = self.new_module(parent,
 573                                              module_kind,
 574                                              parent.normal_ancestor_id,
 575                                              expansion,
 576                                              item.span);
 577                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 578                 self.current_module = module;
 579             }
 580
 581             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 582         }
 583     }
 584
 585     // Constructs the reduced graph for one variant. Variants exist in the
 586     // type and value namespaces.
 587     fn build_reduced_graph_for_variant(&mut self,
 588                                        variant: &Variant,
 589                                        parent: Module<'a>,
 590                                        vis: ty::Visibility,
 591                                        expansion: Mark) {
 592         let ident = variant.node.ident;
 593
 594         // Define a name in the type namespace.
 595         let def_id = self.definitions.local_def_id(variant.node.id);
 596         let res = Res::Def(DefKind::Variant, def_id);
 597         self.define(parent, ident, TypeNS, (res, vis, variant.span, expansion));
 598
 599         // If the variant is marked as non_exhaustive then lower the visibility to within the
 600         // crate.
 601         let mut ctor_vis = vis;
 602         let has_non_exhaustive = attr::contains_name(&variant.node.attrs, sym::non_exhaustive);
 603         if has_non_exhaustive && vis == ty::Visibility::Public {
 604             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 605         }
 606
 607         // Define a constructor name in the value namespace.
 608         // Braced variants, unlike structs, generate unusable names in
 609         // value namespace, they are reserved for possible future use.
 610         // It's ok to use the variant's id as a ctor id since an
 611         // error will be reported on any use of such resolution anyway.
 612         let ctor_node_id = variant.node.data.ctor_id().unwrap_or(variant.node.id);
 613         let ctor_def_id = self.definitions.local_def_id(ctor_node_id);
 614         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 615         let ctor_res = Res::Def(DefKind::Ctor(CtorOf::Variant, ctor_kind), ctor_def_id);
 616         self.define(parent, ident, ValueNS, (ctor_res, ctor_vis, variant.span, expansion));
 617     }
 618
 619     /// Constructs the reduced graph for one foreign item.
 620     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 621         let (res, ns) = match item.node {
 622             ForeignItemKind::Fn(..) => {
 623                 (Res::Def(DefKind::Fn, self.definitions.local_def_id(item.id)), ValueNS)
 624             }
 625             ForeignItemKind::Static(..) => {
 626                 (Res::Def(DefKind::Static, self.definitions.local_def_id(item.id)), ValueNS)
 627             }
 628             ForeignItemKind::Ty => {
 629                 (Res::Def(DefKind::ForeignTy, self.definitions.local_def_id(item.id)), TypeNS)
 630             }
 631             ForeignItemKind::Macro(_) => unreachable!(),
 632         };
 633         let parent = self.current_module;
 634         let vis = self.resolve_visibility(&item.vis);
 635         self.define(parent, item.ident, ns, (res, vis, item.span, expansion));
 636     }
 637
 638     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 639         let parent = self.current_module;
 640         if self.block_needs_anonymous_module(block) {
 641             let module = self.new_module(parent,
 642                                          ModuleKind::Block(block.id),
 643                                          parent.normal_ancestor_id,
 644                                          expansion,
 645                                          block.span);
 646             self.block_map.insert(block.id, module);
 647             self.current_module = module; // Descend into the block.
 648         }
 649     }
 650
 651     /// Builds the reduced graph for a single item in an external crate.
 652     fn build_reduced_graph_for_external_crate_res(
 653         &mut self,
 654         parent: Module<'a>,
 655         child: Export<ast::NodeId>,
 656     ) {
 657         let Export { ident, res, vis, span } = child;
 658         // FIXME: We shouldn't create the gensym here, it should come from metadata,
 659         // but metadata cannot encode gensyms currently, so we create it here.
 660         // This is only a guess, two equivalent idents may incorrectly get different gensyms here.
 661         let ident = ident.gensym_if_underscore();
 662         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 663         match res {
 664             Res::Def(kind @ DefKind::Mod, def_id)
 665             | Res::Def(kind @ DefKind::Enum, def_id) => {
 666                 let module = self.new_module(parent,
 667                                              ModuleKind::Def(kind, def_id, ident.name),
 668                                              def_id,
 669                                              expansion,
 670                                              span);
 671                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 672             }
 673             Res::Def(DefKind::Variant, _)
 674             | Res::Def(DefKind::TyAlias, _)
 675             | Res::Def(DefKind::ForeignTy, _)
 676             | Res::Def(DefKind::Existential, _)
 677             | Res::Def(DefKind::TraitAlias, _)
 678             | Res::PrimTy(..)
 679             | Res::ToolMod => {
 680                 self.define(parent, ident, TypeNS, (res, vis, DUMMY_SP, expansion));
 681             }
 682             Res::Def(DefKind::Fn, _)
 683             | Res::Def(DefKind::Static, _)
 684             | Res::Def(DefKind::Const, _)
 685             | Res::Def(DefKind::Ctor(CtorOf::Variant, ..), _) => {
 686                 self.define(parent, ident, ValueNS, (res, vis, DUMMY_SP, expansion));
 687             }
 688             Res::Def(DefKind::Ctor(CtorOf::Struct, ..), def_id) => {
 689                 self.define(parent, ident, ValueNS, (res, vis, DUMMY_SP, expansion));
 690
 691                 if let Some(struct_def_id) =
 692                         self.cstore.def_key(def_id).parent
 693                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 694                     self.struct_constructors.insert(struct_def_id, (res, vis));
 695                 }
 696             }
 697             Res::Def(DefKind::Trait, def_id) => {
 698                 let module_kind = ModuleKind::Def(DefKind::Trait, def_id, ident.name);
 699                 let module = self.new_module(parent,
 700                                              module_kind,
 701                                              parent.normal_ancestor_id,
 702                                              expansion,
 703                                              span);
 704                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 705
 706                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 707                     let res = child.res.map_id(|_| panic!("unexpected id"));
 708                     let ns = if let Res::Def(DefKind::AssocTy, _) = res {
 709                         TypeNS
 710                     } else { ValueNS };
 711                     self.define(module, child.ident, ns,
 712                                 (res, ty::Visibility::Public, DUMMY_SP, expansion));
 713
 714                     if self.cstore.associated_item_cloned_untracked(child.res.def_id())
 715                            .method_has_self_argument {
 716                         self.has_self.insert(res.def_id());
 717                     }
 718                 }
 719                 module.populated.set(true);
 720             }
 721             Res::Def(DefKind::Struct, def_id) | Res::Def(DefKind::Union, def_id) => {
 722                 self.define(parent, ident, TypeNS, (res, vis, DUMMY_SP, expansion));
 723
 724                 // Record field names for error reporting.
 725                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 726                 self.insert_field_names(def_id, field_names);
 727             }
 728             Res::Def(DefKind::Macro(..), _) | Res::NonMacroAttr(..) => {
 729                 self.define(parent, ident, MacroNS, (res, vis, DUMMY_SP, expansion));
 730             }
 731             _ => bug!("unexpected resolution: {:?}", res)
 732         }
 733     }
 734
 735     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 736         if def_id.krate == LOCAL_CRATE {
 737             return self.module_map[&def_id]
 738         }
 739
 740         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 741         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 742             return module;
 743         }
 744
 745         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 746             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 747         } else {
 748             let def_key = self.cstore.def_key(def_id);
 749             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 750              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 751         };
 752
 753         let kind = ModuleKind::Def(DefKind::Mod, def_id, name.as_symbol());
 754         let module =
 755             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 756         self.extern_module_map.insert((def_id, macros_only), module);
 757         module
 758     }
 759
 760     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 761         let def_id = self.macro_defs[&expansion];
 762         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 763             self.local_macro_def_scopes[&id]
 764         } else if def_id.krate == CrateNum::BuiltinMacros {
 765             self.injected_crate.unwrap_or(self.graph_root)
 766         } else {
 767             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 768             self.get_module(module_def_id)
 769         }
 770     }
 771
 772     pub fn get_macro(&mut self, res: Res) -> Lrc<SyntaxExtension> {
 773         let def_id = match res {
 774             Res::Def(DefKind::Macro(..), def_id) => def_id,
 775             Res::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 776                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 777             }),
 778             _ => panic!("expected `DefKind::Macro` or `Res::NonMacroAttr`"),
 779         };
 780         if let Some(ext) = self.macro_map.get(&def_id) {
 781             return ext.clone();
 782         }
 783
 784         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 785             LoadedMacro::MacroDef(macro_def) => macro_def,
 786             LoadedMacro::ProcMacro(ext) => return ext,
 787         };
 788
 789         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 790                                                &self.session.features_untracked(),
 791                                                &macro_def,
 792                                                self.cstore.crate_edition_untracked(def_id.krate)));
 793         self.macro_map.insert(def_id, ext.clone());
 794         ext
 795     }
 796
 797     /// Ensures that the reduced graph rooted at the given external module
 798     /// is built, building it if it is not.
 799     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 800         if module.populated.get() { return }
 801         let def_id = module.def_id().unwrap();
 802         for child in self.cstore.item_children_untracked(def_id, self.session) {
 803             let child = child.map_id(|_| panic!("unexpected id"));
 804             self.build_reduced_graph_for_external_crate_res(module, child);
 805         }
 806         module.populated.set(true)
 807     }
 808
 809     fn legacy_import_macro(&mut self,
 810                            name: Name,
 811                            binding: &'a NameBinding<'a>,
 812                            span: Span,
 813                            allow_shadowing: bool) {
 814         if self.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 815             let msg = format!("`{}` is already in scope", name);
 816             let note =
 817                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 818             self.session.struct_span_err(span, &msg).note(note).emit();
 819         }
 820     }
 821
 822     /// Returns `true` if we should consider the underlying `extern crate` to be used.
 823     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>,
 824                                     parent_scope: &ParentScope<'a>) -> bool {
 825         let mut import_all = None;
 826         let mut single_imports = Vec::new();
 827         for attr in &item.attrs {
 828             if attr.check_name(sym::macro_use) {
 829                 if self.current_module.parent.is_some() {
 830                     span_err!(self.session, item.span, E0468,
 831                         "an `extern crate` loading macros must be at the crate root");
 832                 }
 833                 if let ItemKind::ExternCrate(Some(orig_name)) = item.node {
 834                     if orig_name == kw::SelfLower {
 835                         self.session.span_err(attr.span,
 836                             "`macro_use` is not supported on `extern crate self`");
 837                     }
 838                 }
 839                 let ill_formed = |span| span_err!(self.session, span, E0466, "bad macro import");
 840                 match attr.meta() {
 841                     Some(meta) => match meta.node {
 842                         MetaItemKind::Word => {
 843                             import_all = Some(meta.span);
 844                             break;
 845                         }
 846                         MetaItemKind::List(nested_metas) => for nested_meta in nested_metas {
 847                             match nested_meta.ident() {
 848                                 Some(ident) if nested_meta.is_word() => single_imports.push(ident),
 849                                 _ => ill_formed(nested_meta.span()),
 850                             }
 851                         }
 852                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 853                     }
 854                     None => ill_formed(attr.span),
 855                 }
 856             }
 857         }
 858
 859         let arenas = self.arenas;
 860         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 861             root_id: item.id,
 862             id: item.id,
 863             parent_scope: parent_scope.clone(),
 864             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 865             subclass: ImportDirectiveSubclass::MacroUse,
 866             use_span_with_attributes: item.span_with_attributes(),
 867             has_attributes: !item.attrs.is_empty(),
 868             use_span: item.span,
 869             root_span: span,
 870             span,
 871             module_path: Vec::new(),
 872             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 873             used: Cell::new(false),
 874         });
 875
 876         let allow_shadowing = parent_scope.expansion == Mark::root();
 877         if let Some(span) = import_all {
 878             let directive = macro_use_directive(span);
 879             self.potentially_unused_imports.push(directive);
 880             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 881                 let imported_binding = self.import(binding, directive);
 882                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 883             });
 884         } else {
 885             for ident in single_imports.iter().cloned() {
 886                 let result = self.resolve_ident_in_module(
 887                     ModuleOrUniformRoot::Module(module),
 888                     ident,
 889                     MacroNS,
 890                     None,
 891                     false,
 892                     ident.span,
 893                 );
 894                 if let Ok(binding) = result {
 895                     let directive = macro_use_directive(ident.span);
 896                     self.potentially_unused_imports.push(directive);
 897                     let imported_binding = self.import(binding, directive);
 898                     self.legacy_import_macro(ident.name, imported_binding,
 899                                              ident.span, allow_shadowing);
 900                 } else {
 901                     span_err!(self.session, ident.span, E0469, "imported macro not found");
 902                 }
 903             }
 904         }
 905         import_all.is_some() || !single_imports.is_empty()
 906     }
 907
 908     /// Returns `true` if this attribute list contains `macro_use`.
 909     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 910         for attr in attrs {
 911             if attr.check_name(sym::macro_escape) {
 912                 let msg = "macro_escape is a deprecated synonym for macro_use";
 913                 let mut err = self.session.struct_span_warn(attr.span, msg);
 914                 if let ast::AttrStyle::Inner = attr.style {
 915                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 916                 } else {
 917                     err.emit();
 918                 }
 919             } else if !attr.check_name(sym::macro_use) {
 920                 continue;
 921             }
 922
 923             if !attr.is_word() {
 924                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 925             }
 926             return true;
 927         }
 928
 929         false
 930     }
 931 }
 932
 933 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 934     pub resolver: &'a mut Resolver<'b>,
 935     pub current_legacy_scope: LegacyScope<'b>,
 936     pub expansion: Mark,
 937 }
 938
 939 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 940     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 941         let mark = id.placeholder_to_mark();
 942         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 943         let invocation = self.resolver.invocations[&mark];
 944         invocation.module.set(self.resolver.current_module);
 945         invocation.parent_legacy_scope.set(self.current_legacy_scope);
 946         invocation
 947     }
 948 }
 949
 950 macro_rules! method {
 951     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 952         fn $visit(&mut self, node: &'a $ty) {
 953             if let $invoc(..) = node.node {
 954                 self.visit_invoc(node.id);
 955             } else {
 956                 visit::$walk(self, node);
 957             }
 958         }
 959     }
 960 }
 961
 962 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 963     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 964     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 965     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 966     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 967
 968     fn visit_item(&mut self, item: &'a Item) {
 969         let macro_use = match item.node {
 970             ItemKind::MacroDef(..) => {
 971                 self.resolver.define_macro(item, self.expansion, &mut self.current_legacy_scope);
 972                 return
 973             }
 974             ItemKind::Mac(..) => {
 975                 self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(item.id));
 976                 return
 977             }
 978             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 979             _ => false,
 980         };
 981
 982         let orig_current_module = self.resolver.current_module;
 983         let orig_current_legacy_scope = self.current_legacy_scope;
 984         let parent_scope = ParentScope {
 985             module: self.resolver.current_module,
 986             expansion: self.expansion,
 987             legacy: self.current_legacy_scope,
 988             derives: Vec::new(),
 989         };
 990         self.resolver.build_reduced_graph_for_item(item, parent_scope);
 991         visit::walk_item(self, item);
 992         self.resolver.current_module = orig_current_module;
 993         if !macro_use {
 994             self.current_legacy_scope = orig_current_legacy_scope;
 995         }
 996     }
 997
 998     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 999         if let ast::StmtKind::Mac(..) = stmt.node {
1000             self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(stmt.id));
1001         } else {
1002             visit::walk_stmt(self, stmt);
1003         }
1004     }
1005
1006     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
1007         if let ForeignItemKind::Macro(_) = foreign_item.node {
1008             self.visit_invoc(foreign_item.id);
1009             return;
1010         }
1011
1012         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
1013         visit::walk_foreign_item(self, foreign_item);
1014     }
1015
1016     fn visit_block(&mut self, block: &'a Block) {
1017         let orig_current_module = self.resolver.current_module;
1018         let orig_current_legacy_scope = self.current_legacy_scope;
1019         self.resolver.build_reduced_graph_for_block(block, self.expansion);
1020         visit::walk_block(self, block);
1021         self.resolver.current_module = orig_current_module;
1022         self.current_legacy_scope = orig_current_legacy_scope;
1023     }
1024
1025     fn visit_trait_item(&mut self, item: &'a TraitItem) {
1026         let parent = self.resolver.current_module;
1027
1028         if let TraitItemKind::Macro(_) = item.node {
1029             self.visit_invoc(item.id);
1030             return
1031         }
1032
1033         // Add the item to the trait info.
1034         let item_def_id = self.resolver.definitions.local_def_id(item.id);
1035         let (res, ns) = match item.node {
1036             TraitItemKind::Const(..) => (Res::Def(DefKind::AssocConst, item_def_id), ValueNS),
1037             TraitItemKind::Method(ref sig, _) => {
1038                 if sig.decl.has_self() {
1039                     self.resolver.has_self.insert(item_def_id);
1040                 }
1041                 (Res::Def(DefKind::Method, item_def_id), ValueNS)
1042             }
1043             TraitItemKind::Type(..) => (Res::Def(DefKind::AssocTy, item_def_id), TypeNS),
1044             TraitItemKind::Macro(_) => bug!(),  // handled above
1045         };
1046
1047         let vis = ty::Visibility::Public;
1048         self.resolver.define(parent, item.ident, ns, (res, vis, item.span, self.expansion));
1049
1050         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
1051         visit::walk_trait_item(self, item);
1052         self.resolver.current_module = parent;
1053     }
1054
1055     fn visit_token(&mut self, t: Token) {
1056         if let Token::Interpolated(nt) = t {
1057             if let token::NtExpr(ref expr) = *nt {
1058                 if let ast::ExprKind::Mac(..) = expr.node {
1059                     self.visit_invoc(expr.id);
1060                 }
1061             }
1062         }
1063     }
1064
1065     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
1066         if !attr.is_sugared_doc && is_builtin_attr(attr) {
1067             let parent_scope = ParentScope {
1068                 module: self.resolver.current_module.nearest_item_scope(),
1069                 expansion: self.expansion,
1070                 legacy: self.current_legacy_scope,
1071                 // Let's hope discerning built-in attributes from derive helpers is not necessary
1072                 derives: Vec::new(),
1073             };
1074             parent_scope.module.builtin_attrs.borrow_mut().push((
1075                 attr.path.segments[0].ident, parent_scope
1076             ));
1077         }
1078         visit::walk_attribute(self, attr);
1079     }
1080 }