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