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 macros::{InvocationData, ParentScope, LegacyScope};
   7 use resolve_imports::ImportDirective;
   8 use resolve_imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
   9 use {Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, Segment, ToNameBinding};
  10 use {ModuleOrUniformRoot, PerNS, Resolver, ResolverArenas, ExternPreludeEntry};
  11 use Namespace::{self, TypeNS, ValueNS, MacroNS};
  12 use {resolve_error, resolve_struct_error, ResolutionError};
  13
  14 use rustc::hir::def::*;
  15 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  16 use rustc::ty;
  17 use rustc::middle::cstore::CrateStore;
  18 use rustc_metadata::cstore::LoadedMacro;
  19
  20 use std::cell::Cell;
  21 use std::ptr;
  22 use rustc_data_structures::sync::Lrc;
  23
  24 use syntax::ast::{Name, Ident};
  25 use syntax::attr;
  26
  27 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  28 use syntax::ast::{MetaItemKind, Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  29 use syntax::ext::base::{MacroKind, SyntaxExtension};
  30 use syntax::ext::base::Determinacy::Undetermined;
  31 use syntax::ext::hygiene::Mark;
  32 use syntax::ext::tt::macro_rules;
  33 use syntax::feature_gate::{is_builtin_attr, emit_feature_err, GateIssue};
  34 use syntax::parse::token::{self, Token};
  35 use syntax::std_inject::injected_crate_name;
  36 use syntax::symbol::keywords;
  37 use syntax::visit::{self, Visitor};
  38
  39 use syntax_pos::{Span, DUMMY_SP};
  40
  41 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  42     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  43         arenas.alloc_name_binding(NameBinding {
  44             kind: NameBindingKind::Module(self.0),
  45             ambiguity: None,
  46             vis: self.1,
  47             span: self.2,
  48             expansion: self.3,
  49         })
  50     }
  51 }
  52
  53 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  54     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  55         arenas.alloc_name_binding(NameBinding {
  56             kind: NameBindingKind::Def(self.0, false),
  57             ambiguity: None,
  58             vis: self.1,
  59             span: self.2,
  60             expansion: self.3,
  61         })
  62     }
  63 }
  64
  65 pub(crate) struct IsMacroExport;
  66
  67 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark, IsMacroExport) {
  68     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  69         arenas.alloc_name_binding(NameBinding {
  70             kind: NameBindingKind::Def(self.0, true),
  71             ambiguity: None,
  72             vis: self.1,
  73             span: self.2,
  74             expansion: self.3,
  75         })
  76     }
  77 }
  78
  79 impl<'a> Resolver<'a> {
  80     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  81     /// otherwise, reports an error.
  82     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  83         where T: ToNameBinding<'a>,
  84     {
  85         let binding = def.to_name_binding(self.arenas);
  86         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  87             self.report_conflict(parent, ident, ns, old_binding, &binding);
  88         }
  89     }
  90
  91     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  92         // If any statements are items, we need to create an anonymous module
  93         block.stmts.iter().any(|statement| match statement.node {
  94             StmtKind::Item(_) | StmtKind::Mac(_) => true,
  95             _ => false,
  96         })
  97     }
  98
  99     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 100         if !field_names.is_empty() {
 101             self.field_names.insert(def_id, field_names);
 102         }
 103     }
 104
 105     fn build_reduced_graph_for_use_tree(
 106         &mut self,
 107         // This particular use tree
 108         use_tree: &ast::UseTree,
 109         id: NodeId,
 110         parent_prefix: &[Segment],
 111         nested: bool,
 112         // The whole `use` item
 113         parent_scope: ParentScope<'a>,
 114         item: &Item,
 115         vis: ty::Visibility,
 116         root_span: Span,
 117     ) {
 118         debug!("build_reduced_graph_for_use_tree(parent_prefix={:?}, use_tree={:?}, nested={})",
 119                parent_prefix, use_tree, nested);
 120
 121         let mut prefix_iter = parent_prefix.iter().cloned()
 122             .chain(use_tree.prefix.segments.iter().map(|seg| seg.into())).peekable();
 123
 124         // On 2015 edition imports are resolved as crate-relative by default,
 125         // so prefixes are prepended with crate root segment if necessary.
 126         // The root is prepended lazily, when the first non-empty prefix or terminating glob
 127         // appears, so imports in braced groups can have roots prepended independently.
 128         // 2015 identifiers used on global 2018 edition enter special "virtual 2015 mode", don't
 129         // get crate root prepended, but get special treatment during in-scope resolution instead.
 130         let is_glob = if let ast::UseTreeKind::Glob = use_tree.kind { true } else { false };
 131         let crate_root = match prefix_iter.peek() {
 132             Some(seg) if !seg.ident.is_path_segment_keyword() &&
 133                          seg.ident.span.rust_2015() && self.session.rust_2015() => {
 134                 Some(seg.ident.span.ctxt())
 135             }
 136             None if is_glob && use_tree.span.rust_2015() => {
 137                 Some(use_tree.span.ctxt())
 138             }
 139             _ => None,
 140         }.map(|ctxt| Segment::from_ident(Ident::new(
 141             keywords::PathRoot.name(), use_tree.prefix.span.shrink_to_lo().with_ctxt(ctxt)
 142         )));
 143
 144         let prefix = crate_root.into_iter().chain(prefix_iter).collect::<Vec<_>>();
 145         debug!("build_reduced_graph_for_use_tree: prefix={:?}", prefix);
 146
 147         let empty_for_self = |prefix: &[Segment]| {
 148             prefix.is_empty() ||
 149             prefix.len() == 1 && prefix[0].ident.name == keywords::PathRoot.name()
 150         };
 151         match use_tree.kind {
 152             ast::UseTreeKind::Simple(rename, ..) => {
 153                 let mut ident = use_tree.ident().gensym_if_underscore();
 154                 let mut module_path = prefix;
 155                 let mut source = module_path.pop().unwrap();
 156                 let mut type_ns_only = false;
 157
 158                 if nested {
 159                     // Correctly handle `self`
 160                     if source.ident.name == keywords::SelfLower.name() {
 161                         type_ns_only = true;
 162
 163                         if empty_for_self(&module_path) {
 164                             resolve_error(
 165                                 self,
 166                                 use_tree.span,
 167                                 ResolutionError::
 168                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 169                             );
 170                             return;
 171                         }
 172
 173                         // Replace `use foo::self;` with `use foo;`
 174                         source = module_path.pop().unwrap();
 175                         if rename.is_none() {
 176                             ident = source.ident;
 177                         }
 178                     }
 179                 } else {
 180                     // Disallow `self`
 181                     if source.ident.name == keywords::SelfLower.name() {
 182                         resolve_error(self,
 183                                       use_tree.span,
 184                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 185                     }
 186
 187                     // Disallow `use $crate;`
 188                     if source.ident.name == keywords::DollarCrate.name() && module_path.is_empty() {
 189                         let crate_root = self.resolve_crate_root(source.ident);
 190                         let crate_name = match crate_root.kind {
 191                             ModuleKind::Def(_, name) => name,
 192                             ModuleKind::Block(..) => unreachable!(),
 193                         };
 194                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 195                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 196                         // while the current crate doesn't have a valid `crate_name`.
 197                         if crate_name != keywords::Invalid.name() {
 198                             // `crate_name` should not be interpreted as relative.
 199                             module_path.push(Segment {
 200                                 ident: Ident {
 201                                     name: keywords::PathRoot.name(),
 202                                     span: source.ident.span,
 203                                 },
 204                                 id: Some(self.session.next_node_id()),
 205                             });
 206                             source.ident.name = crate_name;
 207                         }
 208                         if rename.is_none() {
 209                             ident.name = crate_name;
 210                         }
 211
 212                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 213                             .note("`use $crate;` was erroneously allowed and \
 214                                    will become a hard error in a future release")
 215                             .emit();
 216                     }
 217                 }
 218
 219                 if ident.name == keywords::Crate.name() {
 220                     self.session.span_err(ident.span,
 221                         "crate root imports need to be explicitly named: \
 222                          `use crate as name;`");
 223                 }
 224
 225                 let subclass = SingleImport {
 226                     source: source.ident,
 227                     target: ident,
 228                     source_bindings: PerNS {
 229                         type_ns: Cell::new(Err(Undetermined)),
 230                         value_ns: Cell::new(Err(Undetermined)),
 231                         macro_ns: Cell::new(Err(Undetermined)),
 232                     },
 233                     target_bindings: PerNS {
 234                         type_ns: Cell::new(None),
 235                         value_ns: Cell::new(None),
 236                         macro_ns: Cell::new(None),
 237                     },
 238                     type_ns_only,
 239                 };
 240                 self.add_import_directive(
 241                     module_path,
 242                     subclass,
 243                     use_tree.span,
 244                     id,
 245                     root_span,
 246                     item.id,
 247                     vis,
 248                     parent_scope,
 249                 );
 250             }
 251             ast::UseTreeKind::Glob => {
 252                 let subclass = GlobImport {
 253                     is_prelude: attr::contains_name(&item.attrs, "prelude_import"),
 254                     max_vis: Cell::new(ty::Visibility::Invisible),
 255                 };
 256                 self.add_import_directive(
 257                     prefix,
 258                     subclass,
 259                     use_tree.span,
 260                     id,
 261                     root_span,
 262                     item.id,
 263                     vis,
 264                     parent_scope,
 265                 );
 266             }
 267             ast::UseTreeKind::Nested(ref items) => {
 268                 // Ensure there is at most one `self` in the list
 269                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 270                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 271                         if use_tree.ident().name == keywords::SelfLower.name() {
 272                             return Some(use_tree.span);
 273                         }
 274                     }
 275
 276                     None
 277                 }).collect::<Vec<_>>();
 278                 if self_spans.len() > 1 {
 279                     let mut e = resolve_struct_error(self,
 280                         self_spans[0],
 281                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 282
 283                     for other_span in self_spans.iter().skip(1) {
 284                         e.span_label(*other_span, "another `self` import appears here");
 285                     }
 286
 287                     e.emit();
 288                 }
 289
 290                 for &(ref tree, id) in items {
 291                     self.build_reduced_graph_for_use_tree(
 292                         // This particular use tree
 293                         tree, id, &prefix, true,
 294                         // The whole `use` item
 295                         parent_scope.clone(), item, vis, root_span,
 296                     );
 297                 }
 298
 299                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 300                 // `a::b::c::{self as _}`, so that their prefixes are correctly
 301                 // resolved and checked for privacy/stability/etc.
 302                 if items.is_empty() && !empty_for_self(&prefix) {
 303                     let new_span = prefix[prefix.len() - 1].ident.span;
 304                     let tree = ast::UseTree {
 305                         prefix: ast::Path::from_ident(
 306                             Ident::new(keywords::SelfLower.name(), new_span)
 307                         ),
 308                         kind: ast::UseTreeKind::Simple(
 309                             Some(Ident::new(keywords::Underscore.name().gensymed(), new_span)),
 310                             ast::DUMMY_NODE_ID,
 311                             ast::DUMMY_NODE_ID,
 312                         ),
 313                         span: use_tree.span,
 314                     };
 315                     self.build_reduced_graph_for_use_tree(
 316                         // This particular use tree
 317                         &tree, id, &prefix, true,
 318                         // The whole `use` item
 319                         parent_scope, item, ty::Visibility::Invisible, root_span,
 320                     );
 321                 }
 322             }
 323         }
 324     }
 325
 326     /// Constructs the reduced graph for one item.
 327     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_scope: ParentScope<'a>) {
 328         let parent = parent_scope.module;
 329         let expansion = parent_scope.expansion;
 330         let ident = item.ident.gensym_if_underscore();
 331         let sp = item.span;
 332         let vis = self.resolve_visibility(&item.vis);
 333
 334         match item.node {
 335             ItemKind::Use(ref use_tree) => {
 336                 self.build_reduced_graph_for_use_tree(
 337                     // This particular use tree
 338                     use_tree, item.id, &[], false,
 339                     // The whole `use` item
 340                     parent_scope, item, vis, use_tree.span,
 341                 );
 342             }
 343
 344             ItemKind::ExternCrate(orig_name) => {
 345                 let module = if orig_name.is_none() && ident.name == keywords::SelfLower.name() {
 346                     self.session
 347                         .struct_span_err(item.span, "`extern crate self;` requires renaming")
 348                         .span_suggestion(item.span, "try", "extern crate self as name;".into())
 349                         .emit();
 350                     return;
 351                 } else if orig_name == Some(keywords::SelfLower.name()) {
 352                     if !self.session.features_untracked().extern_crate_self {
 353                         emit_feature_err(&self.session.parse_sess, "extern_crate_self", item.span,
 354                                          GateIssue::Language, "`extern crate self` is unstable");
 355                     }
 356                     self.graph_root
 357                 } else {
 358                     let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 359                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
 360                 };
 361
 362                 self.populate_module_if_necessary(module);
 363                 if injected_crate_name().map_or(false, |name| ident.name == name) {
 364                     self.injected_crate = Some(module);
 365                 }
 366
 367                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
 368                 let binding =
 369                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 370                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 371                     root_id: item.id,
 372                     id: item.id,
 373                     parent_scope,
 374                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 375                     subclass: ImportDirectiveSubclass::ExternCrate {
 376                         source: orig_name,
 377                         target: ident,
 378                     },
 379                     root_span: item.span,
 380                     span: item.span,
 381                     module_path: Vec::new(),
 382                     vis: Cell::new(vis),
 383                     used: Cell::new(used),
 384                 });
 385                 self.potentially_unused_imports.push(directive);
 386                 let imported_binding = self.import(binding, directive);
 387                 if ptr::eq(self.current_module, self.graph_root) {
 388                     if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
 389                         if expansion != Mark::root() && orig_name.is_some() &&
 390                            entry.extern_crate_item.is_none() {
 391                             self.session.span_err(item.span, "macro-expanded `extern crate` items \
 392                                                               cannot shadow names passed with \
 393                                                               `--extern`");
 394                         }
 395                     }
 396                     let entry = self.extern_prelude.entry(ident.modern())
 397                                                    .or_insert(ExternPreludeEntry {
 398                         extern_crate_item: None,
 399                         introduced_by_item: true,
 400                     });
 401                     entry.extern_crate_item = Some(imported_binding);
 402                     if orig_name.is_some() {
 403                         entry.introduced_by_item = true;
 404                     }
 405                 }
 406                 self.define(parent, ident, TypeNS, imported_binding);
 407             }
 408
 409             ItemKind::GlobalAsm(..) => {}
 410
 411             ItemKind::Mod(..) if ident == keywords::Invalid.ident() => {} // Crate root
 412
 413             ItemKind::Mod(..) => {
 414                 let def_id = self.definitions.local_def_id(item.id);
 415                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 416                 let module = self.arenas.alloc_module(ModuleData {
 417                     no_implicit_prelude: parent.no_implicit_prelude || {
 418                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 419                     },
 420                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 421                 });
 422                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 423                 self.module_map.insert(def_id, module);
 424
 425                 // Descend into the module.
 426                 self.current_module = module;
 427             }
 428
 429             // Handled in `rustc_metadata::{native_libs,link_args}`
 430             ItemKind::ForeignMod(..) => {}
 431
 432             // These items live in the value namespace.
 433             ItemKind::Static(_, m, _) => {
 434                 let mutbl = m == Mutability::Mutable;
 435                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 436                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 437             }
 438             ItemKind::Const(..) => {
 439                 let def = Def::Const(self.definitions.local_def_id(item.id));
 440                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 441             }
 442             ItemKind::Fn(..) => {
 443                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 444                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 445
 446                 // Functions introducing procedural macros reserve a slot
 447                 // in the macro namespace as well (see #52225).
 448                 if attr::contains_name(&item.attrs, "proc_macro") ||
 449                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 450                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 451                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 452                 }
 453                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 454                     if let Some(trait_attr) =
 455                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 456                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 457                             let sp = trait_attr.span;
 458                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 459                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 460                         }
 461                     }
 462                 }
 463             }
 464
 465             // These items live in the type namespace.
 466             ItemKind::Ty(..) => {
 467                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 468                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 469             }
 470
 471             ItemKind::Existential(_, _) => {
 472                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 473                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 474             }
 475
 476             ItemKind::Enum(ref enum_definition, _) => {
 477                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 478                 let module_kind = ModuleKind::Def(def, ident.name);
 479                 let module = self.new_module(parent,
 480                                              module_kind,
 481                                              parent.normal_ancestor_id,
 482                                              expansion,
 483                                              item.span);
 484                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 485
 486                 for variant in &(*enum_definition).variants {
 487                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 488                 }
 489             }
 490
 491             ItemKind::TraitAlias(..) => {
 492                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 493                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 494             }
 495
 496             // These items live in both the type and value namespaces.
 497             ItemKind::Struct(ref struct_def, _) => {
 498                 // Define a name in the type namespace.
 499                 let def_id = self.definitions.local_def_id(item.id);
 500                 let def = Def::Struct(def_id);
 501                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 502
 503                 let mut ctor_vis = vis;
 504
 505                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 506
 507                 // If the structure is marked as non_exhaustive then lower the visibility
 508                 // to within the crate.
 509                 if has_non_exhaustive && vis == ty::Visibility::Public {
 510                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 511                 }
 512
 513                 // Record field names for error reporting.
 514                 let field_names = struct_def.fields().iter().filter_map(|field| {
 515                     let field_vis = self.resolve_visibility(&field.vis);
 516                     if ctor_vis.is_at_least(field_vis, &*self) {
 517                         ctor_vis = field_vis;
 518                     }
 519                     field.ident.map(|ident| ident.name)
 520                 }).collect();
 521                 let item_def_id = self.definitions.local_def_id(item.id);
 522                 self.insert_field_names(item_def_id, field_names);
 523
 524                 // If this is a tuple or unit struct, define a name
 525                 // in the value namespace as well.
 526                 if !struct_def.is_struct() {
 527                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 528                                                    CtorKind::from_ast(struct_def));
 529                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 530                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 531                 }
 532             }
 533
 534             ItemKind::Union(ref vdata, _) => {
 535                 let def = Def::Union(self.definitions.local_def_id(item.id));
 536                 self.define(parent, ident, TypeNS, (def, 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(Def::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                                        expansion: Mark) {
 574         let ident = variant.node.ident;
 575         let def_id = self.definitions.local_def_id(variant.node.data.id());
 576
 577         // Define a name in the type namespace.
 578         let def = Def::Variant(def_id);
 579         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 580
 581         // Define a constructor name in the value namespace.
 582         // Braced variants, unlike structs, generate unusable names in
 583         // value namespace, they are reserved for possible future use.
 584         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 585         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 586
 587         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 588     }
 589
 590     /// Constructs the reduced graph for one foreign item.
 591     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 592         let (def, ns) = match item.node {
 593             ForeignItemKind::Fn(..) => {
 594                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 595             }
 596             ForeignItemKind::Static(_, m) => {
 597                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 598             }
 599             ForeignItemKind::Ty => {
 600                 (Def::ForeignTy(self.definitions.local_def_id(item.id)), TypeNS)
 601             }
 602             ForeignItemKind::Macro(_) => unreachable!(),
 603         };
 604         let parent = self.current_module;
 605         let vis = self.resolve_visibility(&item.vis);
 606         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 607     }
 608
 609     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 610         let parent = self.current_module;
 611         if self.block_needs_anonymous_module(block) {
 612             let module = self.new_module(parent,
 613                                          ModuleKind::Block(block.id),
 614                                          parent.normal_ancestor_id,
 615                                          expansion,
 616                                          block.span);
 617             self.block_map.insert(block.id, module);
 618             self.current_module = module; // Descend into the block.
 619         }
 620     }
 621
 622     /// Builds the reduced graph for a single item in an external crate.
 623     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 624         let Export { ident, def, vis, span } = child;
 625         // FIXME: We shouldn't create the gensym here, it should come from metadata,
 626         // but metadata cannot encode gensyms currently, so we create it here.
 627         // This is only a guess, two equivalent idents may incorrectly get different gensyms here.
 628         let ident = ident.gensym_if_underscore();
 629         let def_id = def.def_id();
 630         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 631         match def {
 632             Def::Mod(..) | Def::Enum(..) => {
 633                 let module = self.new_module(parent,
 634                                              ModuleKind::Def(def, ident.name),
 635                                              def_id,
 636                                              expansion,
 637                                              span);
 638                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 639             }
 640             Def::Variant(..) | Def::TyAlias(..) | Def::ForeignTy(..) => {
 641                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 642             }
 643             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 644                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 645             }
 646             Def::StructCtor(..) => {
 647                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 648
 649                 if let Some(struct_def_id) =
 650                         self.cstore.def_key(def_id).parent
 651                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 652                     self.struct_constructors.insert(struct_def_id, (def, vis));
 653                 }
 654             }
 655             Def::Trait(..) => {
 656                 let module_kind = ModuleKind::Def(def, ident.name);
 657                 let module = self.new_module(parent,
 658                                              module_kind,
 659                                              parent.normal_ancestor_id,
 660                                              expansion,
 661                                              span);
 662                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 663
 664                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 665                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 666                     self.define(module, child.ident, ns,
 667                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 668
 669                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 670                            .method_has_self_argument {
 671                         self.has_self.insert(child.def.def_id());
 672                     }
 673                 }
 674                 module.populated.set(true);
 675             }
 676             Def::Struct(..) | Def::Union(..) => {
 677                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 678
 679                 // Record field names for error reporting.
 680                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 681                 self.insert_field_names(def_id, field_names);
 682             }
 683             Def::Macro(..) => {
 684                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 685             }
 686             _ => bug!("unexpected definition: {:?}", def)
 687         }
 688     }
 689
 690     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 691         if def_id.krate == LOCAL_CRATE {
 692             return self.module_map[&def_id]
 693         }
 694
 695         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 696         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 697             return module;
 698         }
 699
 700         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 701             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 702         } else {
 703             let def_key = self.cstore.def_key(def_id);
 704             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 705              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 706         };
 707
 708         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 709         let module =
 710             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 711         self.extern_module_map.insert((def_id, macros_only), module);
 712         module
 713     }
 714
 715     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 716         let def_id = self.macro_defs[&expansion];
 717         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 718             self.local_macro_def_scopes[&id]
 719         } else if def_id.krate == CrateNum::BuiltinMacros {
 720             self.injected_crate.unwrap_or(self.graph_root)
 721         } else {
 722             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 723             self.get_module(module_def_id)
 724         }
 725     }
 726
 727     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 728         let def_id = match def {
 729             Def::Macro(def_id, ..) => def_id,
 730             Def::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 731                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 732             }),
 733             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 734         };
 735         if let Some(ext) = self.macro_map.get(&def_id) {
 736             return ext.clone();
 737         }
 738
 739         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 740             LoadedMacro::MacroDef(macro_def) => macro_def,
 741             LoadedMacro::ProcMacro(ext) => return ext,
 742         };
 743
 744         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 745                                                &self.session.features_untracked(),
 746                                                &macro_def,
 747                                                self.cstore.crate_edition_untracked(def_id.krate)));
 748         self.macro_map.insert(def_id, ext.clone());
 749         ext
 750     }
 751
 752     /// Ensures that the reduced graph rooted at the given external module
 753     /// is built, building it if it is not.
 754     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 755         if module.populated.get() { return }
 756         let def_id = module.def_id().unwrap();
 757         for child in self.cstore.item_children_untracked(def_id, self.session) {
 758             self.build_reduced_graph_for_external_crate_def(module, child);
 759         }
 760         module.populated.set(true)
 761     }
 762
 763     fn legacy_import_macro(&mut self,
 764                            name: Name,
 765                            binding: &'a NameBinding<'a>,
 766                            span: Span,
 767                            allow_shadowing: bool) {
 768         if self.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 769             let msg = format!("`{}` is already in scope", name);
 770             let note =
 771                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 772             self.session.struct_span_err(span, &msg).note(note).emit();
 773         }
 774     }
 775
 776     // This returns true if we should consider the underlying `extern crate` to be used.
 777     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>,
 778                                     parent_scope: &ParentScope<'a>) -> bool {
 779         let mut import_all = None;
 780         let mut single_imports = Vec::new();
 781         for attr in &item.attrs {
 782             if attr.check_name("macro_use") {
 783                 if self.current_module.parent.is_some() {
 784                     span_err!(self.session, item.span, E0468,
 785                         "an `extern crate` loading macros must be at the crate root");
 786                 }
 787                 if let ItemKind::ExternCrate(Some(orig_name)) = item.node {
 788                     if orig_name == keywords::SelfLower.name() {
 789                         self.session.span_err(attr.span,
 790                             "`macro_use` is not supported on `extern crate self`");
 791                     }
 792                 }
 793                 let ill_formed = |span| span_err!(self.session, span, E0466, "bad macro import");
 794                 match attr.meta() {
 795                     Some(meta) => match meta.node {
 796                         MetaItemKind::Word => {
 797                             import_all = Some(meta.span);
 798                             break;
 799                         }
 800                         MetaItemKind::List(nested_metas) => for nested_meta in nested_metas {
 801                             match nested_meta.word() {
 802                                 Some(word) => single_imports.push((word.name(), word.span)),
 803                                 None => ill_formed(nested_meta.span),
 804                             }
 805                         }
 806                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 807                     }
 808                     None => ill_formed(attr.span()),
 809                 }
 810             }
 811         }
 812
 813         let arenas = self.arenas;
 814         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 815             root_id: item.id,
 816             id: item.id,
 817             parent_scope: parent_scope.clone(),
 818             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 819             subclass: ImportDirectiveSubclass::MacroUse,
 820             root_span: span,
 821             span,
 822             module_path: Vec::new(),
 823             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 824             used: Cell::new(false),
 825         });
 826
 827         let allow_shadowing = parent_scope.expansion == Mark::root();
 828         if let Some(span) = import_all {
 829             let directive = macro_use_directive(span);
 830             self.potentially_unused_imports.push(directive);
 831             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 832                 let imported_binding = self.import(binding, directive);
 833                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 834             });
 835         } else {
 836             for (name, span) in single_imports.iter().cloned() {
 837                 let ident = Ident::with_empty_ctxt(name);
 838                 let result = self.resolve_ident_in_module(
 839                     ModuleOrUniformRoot::Module(module),
 840                     ident,
 841                     MacroNS,
 842                     None,
 843                     false,
 844                     span,
 845                 );
 846                 if let Ok(binding) = result {
 847                     let directive = macro_use_directive(span);
 848                     self.potentially_unused_imports.push(directive);
 849                     let imported_binding = self.import(binding, directive);
 850                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 851                 } else {
 852                     span_err!(self.session, span, E0469, "imported macro not found");
 853                 }
 854             }
 855         }
 856         import_all.is_some() || !single_imports.is_empty()
 857     }
 858
 859     // does this attribute list contain "macro_use"?
 860     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 861         for attr in attrs {
 862             if attr.check_name("macro_escape") {
 863                 let msg = "macro_escape is a deprecated synonym for macro_use";
 864                 let mut err = self.session.struct_span_warn(attr.span, msg);
 865                 if let ast::AttrStyle::Inner = attr.style {
 866                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 867                 } else {
 868                     err.emit();
 869                 }
 870             } else if !attr.check_name("macro_use") {
 871                 continue;
 872             }
 873
 874             if !attr.is_word() {
 875                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 876             }
 877             return true;
 878         }
 879
 880         false
 881     }
 882 }
 883
 884 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 885     pub resolver: &'a mut Resolver<'b>,
 886     pub current_legacy_scope: LegacyScope<'b>,
 887     pub expansion: Mark,
 888 }
 889
 890 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 891     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 892         let mark = id.placeholder_to_mark();
 893         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 894         let invocation = self.resolver.invocations[&mark];
 895         invocation.module.set(self.resolver.current_module);
 896         invocation.parent_legacy_scope.set(self.current_legacy_scope);
 897         invocation
 898     }
 899 }
 900
 901 macro_rules! method {
 902     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 903         fn $visit(&mut self, node: &'a $ty) {
 904             if let $invoc(..) = node.node {
 905                 self.visit_invoc(node.id);
 906             } else {
 907                 visit::$walk(self, node);
 908             }
 909         }
 910     }
 911 }
 912
 913 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 914     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 915     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 916     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 917     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 918
 919     fn visit_item(&mut self, item: &'a Item) {
 920         let macro_use = match item.node {
 921             ItemKind::MacroDef(..) => {
 922                 self.resolver.define_macro(item, self.expansion, &mut self.current_legacy_scope);
 923                 return
 924             }
 925             ItemKind::Mac(..) => {
 926                 self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(item.id));
 927                 return
 928             }
 929             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 930             _ => false,
 931         };
 932
 933         let orig_current_module = self.resolver.current_module;
 934         let orig_current_legacy_scope = self.current_legacy_scope;
 935         let parent_scope = ParentScope {
 936             module: self.resolver.current_module,
 937             expansion: self.expansion,
 938             legacy: self.current_legacy_scope,
 939             derives: Vec::new(),
 940         };
 941         self.resolver.build_reduced_graph_for_item(item, parent_scope);
 942         visit::walk_item(self, item);
 943         self.resolver.current_module = orig_current_module;
 944         if !macro_use {
 945             self.current_legacy_scope = orig_current_legacy_scope;
 946         }
 947     }
 948
 949     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 950         if let ast::StmtKind::Mac(..) = stmt.node {
 951             self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(stmt.id));
 952         } else {
 953             visit::walk_stmt(self, stmt);
 954         }
 955     }
 956
 957     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 958         if let ForeignItemKind::Macro(_) = foreign_item.node {
 959             self.visit_invoc(foreign_item.id);
 960             return;
 961         }
 962
 963         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 964         visit::walk_foreign_item(self, foreign_item);
 965     }
 966
 967     fn visit_block(&mut self, block: &'a Block) {
 968         let orig_current_module = self.resolver.current_module;
 969         let orig_current_legacy_scope = self.current_legacy_scope;
 970         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 971         visit::walk_block(self, block);
 972         self.resolver.current_module = orig_current_module;
 973         self.current_legacy_scope = orig_current_legacy_scope;
 974     }
 975
 976     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 977         let parent = self.resolver.current_module;
 978
 979         if let TraitItemKind::Macro(_) = item.node {
 980             self.visit_invoc(item.id);
 981             return
 982         }
 983
 984         // Add the item to the trait info.
 985         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 986         let (def, ns) = match item.node {
 987             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 988             TraitItemKind::Method(ref sig, _) => {
 989                 if sig.decl.has_self() {
 990                     self.resolver.has_self.insert(item_def_id);
 991                 }
 992                 (Def::Method(item_def_id), ValueNS)
 993             }
 994             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 995             TraitItemKind::Macro(_) => bug!(),  // handled above
 996         };
 997
 998         let vis = ty::Visibility::Public;
 999         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
1000
1001         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
1002         visit::walk_trait_item(self, item);
1003         self.resolver.current_module = parent;
1004     }
1005
1006     fn visit_token(&mut self, t: Token) {
1007         if let Token::Interpolated(nt) = t {
1008             if let token::NtExpr(ref expr) = nt.0 {
1009                 if let ast::ExprKind::Mac(..) = expr.node {
1010                     self.visit_invoc(expr.id);
1011                 }
1012             }
1013         }
1014     }
1015
1016     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
1017         if !attr.is_sugared_doc && is_builtin_attr(attr) {
1018             let parent_scope = ParentScope {
1019                 module: self.resolver.current_module.nearest_item_scope(),
1020                 expansion: self.expansion,
1021                 legacy: self.current_legacy_scope,
1022                 // Let's hope discerning built-in attributes from derive helpers is not necessary
1023                 derives: Vec::new(),
1024             };
1025             parent_scope.module.builtin_attrs.borrow_mut().push((
1026                 attr.path.segments[0].ident, parent_scope
1027             ));
1028         }
1029         visit::walk_attribute(self, attr);
1030     }
1031 }