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