src/librustc_resolve/build_reduced_graph.rs

   1 //! Reduced graph building.
   2 //!
   3 //! Here we build the "reduced graph": the graph of the module tree without
   4 //! any imports resolved.
   5
   6 use crate::macros::{InvocationData, ParentScope, LegacyScope};
   7 use crate::resolve_imports::ImportDirective;
   8 use crate::resolve_imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
   9 use crate::{Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, Segment, ToNameBinding};
  10 use crate::{ModuleOrUniformRoot, PerNS, Resolver, ResolverArenas, ExternPreludeEntry};
  11 use crate::Namespace::{self, TypeNS, ValueNS, MacroNS};
  12 use crate::{resolve_error, resolve_struct_error, ResolutionError};
  13
  14 use rustc::bug;
  15 use rustc::hir::def::*;
  16 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  17 use rustc::ty;
  18 use rustc::middle::cstore::CrateStore;
  19 use rustc_metadata::cstore::LoadedMacro;
  20
  21 use std::cell::Cell;
  22 use std::ptr;
  23 use rustc_data_structures::sync::Lrc;
  24
  25 use errors::Applicability;
  26
  27 use syntax::ast::{Name, Ident};
  28 use syntax::attr;
  29
  30 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  31 use syntax::ast::{MetaItemKind, Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  32 use syntax::ext::base::{MacroKind, SyntaxExtension};
  33 use syntax::ext::base::Determinacy::Undetermined;
  34 use syntax::ext::hygiene::Mark;
  35 use syntax::ext::tt::macro_rules;
  36 use syntax::feature_gate::is_builtin_attr;
  37 use syntax::parse::token::{self, Token};
  38 use syntax::span_err;
  39 use syntax::std_inject::injected_crate_name;
  40 use syntax::symbol::keywords;
  41 use syntax::visit::{self, Visitor};
  42
  43 use syntax_pos::{Span, DUMMY_SP};
  44
  45 use log::debug;
  46
  47 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  48     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  49         arenas.alloc_name_binding(NameBinding {
  50             kind: NameBindingKind::Module(self.0),
  51             ambiguity: None,
  52             vis: self.1,
  53             span: self.2,
  54             expansion: self.3,
  55         })
  56     }
  57 }
  58
  59 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  60     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  61         arenas.alloc_name_binding(NameBinding {
  62             kind: NameBindingKind::Def(self.0, false),
  63             ambiguity: None,
  64             vis: self.1,
  65             span: self.2,
  66             expansion: self.3,
  67         })
  68     }
  69 }
  70
  71 pub(crate) struct IsMacroExport;
  72
  73 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark, IsMacroExport) {
  74     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  75         arenas.alloc_name_binding(NameBinding {
  76             kind: NameBindingKind::Def(self.0, true),
  77             ambiguity: None,
  78             vis: self.1,
  79             span: self.2,
  80             expansion: self.3,
  81         })
  82     }
  83 }
  84
  85 impl<'a> Resolver<'a> {
  86     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  87     /// otherwise, reports an error.
  88     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  89         where T: ToNameBinding<'a>,
  90     {
  91         let binding = def.to_name_binding(self.arenas);
  92         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  93             self.report_conflict(parent, ident, ns, old_binding, &binding);
  94         }
  95     }
  96
  97     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  98         // If any statements are items, we need to create an anonymous module
  99         block.stmts.iter().any(|statement| match statement.node {
 100             StmtKind::Item(_) | StmtKind::Mac(_) => true,
 101             _ => false,
 102         })
 103     }
 104
 105     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 106         if !field_names.is_empty() {
 107             self.field_names.insert(def_id, field_names);
 108         }
 109     }
 110
 111     fn build_reduced_graph_for_use_tree(
 112         &mut self,
 113         // This particular use tree
 114         use_tree: &ast::UseTree,
 115         id: NodeId,
 116         parent_prefix: &[Segment],
 117         nested: bool,
 118         // The whole `use` item
 119         parent_scope: ParentScope<'a>,
 120         item: &Item,
 121         vis: ty::Visibility,
 122         root_span: Span,
 123     ) {
 124         debug!("build_reduced_graph_for_use_tree(parent_prefix={:?}, use_tree={:?}, nested={})",
 125                parent_prefix, use_tree, nested);
 126
 127         let mut prefix_iter = parent_prefix.iter().cloned()
 128             .chain(use_tree.prefix.segments.iter().map(|seg| seg.into())).peekable();
 129
 130         // On 2015 edition imports are resolved as crate-relative by default,
 131         // so prefixes are prepended with crate root segment if necessary.
 132         // The root is prepended lazily, when the first non-empty prefix or terminating glob
 133         // appears, so imports in braced groups can have roots prepended independently.
 134         // 2015 identifiers used on global 2018 edition enter special "virtual 2015 mode", don't
 135         // get crate root prepended, but get special treatment during in-scope resolution instead.
 136         let is_glob = if let ast::UseTreeKind::Glob = use_tree.kind { true } else { false };
 137         let crate_root = match prefix_iter.peek() {
 138             Some(seg) if !seg.ident.is_path_segment_keyword() &&
 139                          seg.ident.span.rust_2015() && self.session.rust_2015() => {
 140                 Some(seg.ident.span.ctxt())
 141             }
 142             None if is_glob && use_tree.span.rust_2015() => {
 143                 Some(use_tree.span.ctxt())
 144             }
 145             _ => None,
 146         }.map(|ctxt| Segment::from_ident(Ident::new(
 147             keywords::PathRoot.name(), use_tree.prefix.span.shrink_to_lo().with_ctxt(ctxt)
 148         )));
 149
 150         let prefix = crate_root.into_iter().chain(prefix_iter).collect::<Vec<_>>();
 151         debug!("build_reduced_graph_for_use_tree: prefix={:?}", prefix);
 152
 153         let empty_for_self = |prefix: &[Segment]| {
 154             prefix.is_empty() ||
 155             prefix.len() == 1 && prefix[0].ident.name == keywords::PathRoot.name()
 156         };
 157         match use_tree.kind {
 158             ast::UseTreeKind::Simple(rename, ..) => {
 159                 let mut ident = use_tree.ident().gensym_if_underscore();
 160                 let mut module_path = prefix;
 161                 let mut source = module_path.pop().unwrap();
 162                 let mut type_ns_only = false;
 163
 164                 if nested {
 165                     // Correctly handle `self`
 166                     if source.ident.name == keywords::SelfLower.name() {
 167                         type_ns_only = true;
 168
 169                         if empty_for_self(&module_path) {
 170                             resolve_error(
 171                                 self,
 172                                 use_tree.span,
 173                                 ResolutionError::
 174                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 175                             );
 176                             return;
 177                         }
 178
 179                         // Replace `use foo::self;` with `use foo;`
 180                         source = module_path.pop().unwrap();
 181                         if rename.is_none() {
 182                             ident = source.ident;
 183                         }
 184                     }
 185                 } else {
 186                     // Disallow `self`
 187                     if source.ident.name == keywords::SelfLower.name() {
 188                         resolve_error(self,
 189                                       use_tree.span,
 190                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 191                     }
 192
 193                     // Disallow `use $crate;`
 194                     if source.ident.name == keywords::DollarCrate.name() && module_path.is_empty() {
 195                         let crate_root = self.resolve_crate_root(source.ident);
 196                         let crate_name = match crate_root.kind {
 197                             ModuleKind::Def(_, name) => name,
 198                             ModuleKind::Block(..) => unreachable!(),
 199                         };
 200                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 201                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 202                         // while the current crate doesn't have a valid `crate_name`.
 203                         if crate_name != keywords::Invalid.name() {
 204                             // `crate_name` should not be interpreted as relative.
 205                             module_path.push(Segment {
 206                                 ident: Ident {
 207                                     name: keywords::PathRoot.name(),
 208                                     span: source.ident.span,
 209                                 },
 210                                 id: Some(self.session.next_node_id()),
 211                             });
 212                             source.ident.name = crate_name;
 213                         }
 214                         if rename.is_none() {
 215                             ident.name = crate_name;
 216                         }
 217
 218                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 219                             .note("`use $crate;` was erroneously allowed and \
 220                                    will become a hard error in a future release")
 221                             .emit();
 222                     }
 223                 }
 224
 225                 if ident.name == keywords::Crate.name() {
 226                     self.session.span_err(ident.span,
 227                         "crate root imports need to be explicitly named: \
 228                          `use crate as name;`");
 229                 }
 230
 231                 let subclass = SingleImport {
 232                     source: source.ident,
 233                     target: ident,
 234                     source_bindings: PerNS {
 235                         type_ns: Cell::new(Err(Undetermined)),
 236                         value_ns: Cell::new(Err(Undetermined)),
 237                         macro_ns: Cell::new(Err(Undetermined)),
 238                     },
 239                     target_bindings: PerNS {
 240                         type_ns: Cell::new(None),
 241                         value_ns: Cell::new(None),
 242                         macro_ns: Cell::new(None),
 243                     },
 244                     type_ns_only,
 245                     nested,
 246                 };
 247                 self.add_import_directive(
 248                     module_path,
 249                     subclass,
 250                     use_tree.span,
 251                     id,
 252                     item,
 253                     root_span,
 254                     item.id,
 255                     vis,
 256                     parent_scope,
 257                 );
 258             }
 259             ast::UseTreeKind::Glob => {
 260                 let subclass = GlobImport {
 261                     is_prelude: attr::contains_name(&item.attrs, "prelude_import"),
 262                     max_vis: Cell::new(ty::Visibility::Invisible),
 263                 };
 264                 self.add_import_directive(
 265                     prefix,
 266                     subclass,
 267                     use_tree.span,
 268                     id,
 269                     item,
 270                     root_span,
 271                     item.id,
 272                     vis,
 273                     parent_scope,
 274                 );
 275             }
 276             ast::UseTreeKind::Nested(ref items) => {
 277                 // Ensure there is at most one `self` in the list
 278                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 279                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 280                         if use_tree.ident().name == keywords::SelfLower.name() {
 281                             return Some(use_tree.span);
 282                         }
 283                     }
 284
 285                     None
 286                 }).collect::<Vec<_>>();
 287                 if self_spans.len() > 1 {
 288                     let mut e = resolve_struct_error(self,
 289                         self_spans[0],
 290                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 291
 292                     for other_span in self_spans.iter().skip(1) {
 293                         e.span_label(*other_span, "another `self` import appears here");
 294                     }
 295
 296                     e.emit();
 297                 }
 298
 299                 for &(ref tree, id) in items {
 300                     self.build_reduced_graph_for_use_tree(
 301                         // This particular use tree
 302                         tree, id, &prefix, true,
 303                         // The whole `use` item
 304                         parent_scope.clone(), item, vis, root_span,
 305                     );
 306                 }
 307
 308                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 309                 // `a::b::c::{self as _}`, so that their prefixes are correctly
 310                 // resolved and checked for privacy/stability/etc.
 311                 if items.is_empty() && !empty_for_self(&prefix) {
 312                     let new_span = prefix[prefix.len() - 1].ident.span;
 313                     let tree = ast::UseTree {
 314                         prefix: ast::Path::from_ident(
 315                             Ident::new(keywords::SelfLower.name(), new_span)
 316                         ),
 317                         kind: ast::UseTreeKind::Simple(
 318                             Some(Ident::new(keywords::Underscore.name().gensymed(), new_span)),
 319                             ast::DUMMY_NODE_ID,
 320                             ast::DUMMY_NODE_ID,
 321                         ),
 322                         span: use_tree.span,
 323                     };
 324                     self.build_reduced_graph_for_use_tree(
 325                         // This particular use tree
 326                         &tree, id, &prefix, true,
 327                         // The whole `use` item
 328                         parent_scope, item, ty::Visibility::Invisible, root_span,
 329                     );
 330                 }
 331             }
 332         }
 333     }
 334
 335     /// Constructs the reduced graph for one item.
 336     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_scope: ParentScope<'a>) {
 337         let parent = parent_scope.module;
 338         let expansion = parent_scope.expansion;
 339         let ident = item.ident.gensym_if_underscore();
 340         let sp = item.span;
 341         let vis = self.resolve_visibility(&item.vis);
 342
 343         match item.node {
 344             ItemKind::Use(ref use_tree) => {
 345                 self.build_reduced_graph_for_use_tree(
 346                     // This particular use tree
 347                     use_tree, item.id, &[], false,
 348                     // The whole `use` item
 349                     parent_scope, item, vis, use_tree.span,
 350                 );
 351             }
 352
 353             ItemKind::ExternCrate(orig_name) => {
 354                 let module = if orig_name.is_none() && ident.name == keywords::SelfLower.name() {
 355                     self.session
 356                         .struct_span_err(item.span, "`extern crate self;` requires renaming")
 357                         .span_suggestion(
 358                             item.span,
 359                             "try",
 360                             "extern crate self as name;".into(),
 361                             Applicability::HasPlaceholders,
 362                         )
 363                         .emit();
 364                     return;
 365                 } else if orig_name == Some(keywords::SelfLower.name()) {
 366                     self.graph_root
 367                 } else {
 368                     let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 369                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
 370                 };
 371
 372                 self.populate_module_if_necessary(module);
 373                 if injected_crate_name().map_or(false, |name| ident.name == name) {
 374                     self.injected_crate = Some(module);
 375                 }
 376
 377                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
 378                 let binding =
 379                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 380                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 381                     root_id: item.id,
 382                     id: item.id,
 383                     parent_scope,
 384                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 385                     subclass: ImportDirectiveSubclass::ExternCrate {
 386                         source: orig_name,
 387                         target: ident,
 388                     },
 389                     has_attributes: !item.attrs.is_empty(),
 390                     use_span_with_attributes: item.span_with_attributes(),
 391                     use_span: item.span,
 392                     root_span: item.span,
 393                     span: item.span,
 394                     module_path: Vec::new(),
 395                     vis: Cell::new(vis),
 396                     used: Cell::new(used),
 397                 });
 398                 self.potentially_unused_imports.push(directive);
 399                 let imported_binding = self.import(binding, directive);
 400                 if ptr::eq(self.current_module, self.graph_root) {
 401                     if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
 402                         if expansion != Mark::root() && orig_name.is_some() &&
 403                            entry.extern_crate_item.is_none() {
 404                             self.session.span_err(item.span, "macro-expanded `extern crate` items \
 405                                                               cannot shadow names passed with \
 406                                                               `--extern`");
 407                         }
 408                     }
 409                     let entry = self.extern_prelude.entry(ident.modern())
 410                                                    .or_insert(ExternPreludeEntry {
 411                         extern_crate_item: None,
 412                         introduced_by_item: true,
 413                     });
 414                     entry.extern_crate_item = Some(imported_binding);
 415                     if orig_name.is_some() {
 416                         entry.introduced_by_item = true;
 417                     }
 418                 }
 419                 self.define(parent, ident, TypeNS, imported_binding);
 420             }
 421
 422             ItemKind::GlobalAsm(..) => {}
 423
 424             ItemKind::Mod(..) if ident == keywords::Invalid.ident() => {} // Crate root
 425
 426             ItemKind::Mod(..) => {
 427                 let def_id = self.definitions.local_def_id(item.id);
 428                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 429                 let module = self.arenas.alloc_module(ModuleData {
 430                     no_implicit_prelude: parent.no_implicit_prelude || {
 431                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 432                     },
 433                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 434                 });
 435                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 436                 self.module_map.insert(def_id, module);
 437
 438                 // Descend into the module.
 439                 self.current_module = module;
 440             }
 441
 442             // Handled in `rustc_metadata::{native_libs,link_args}`
 443             ItemKind::ForeignMod(..) => {}
 444
 445             // These items live in the value namespace.
 446             ItemKind::Static(_, m, _) => {
 447                 let mutbl = m == Mutability::Mutable;
 448                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 449                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 450             }
 451             ItemKind::Const(..) => {
 452                 let def = Def::Const(self.definitions.local_def_id(item.id));
 453                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 454             }
 455             ItemKind::Fn(..) => {
 456                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 457                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 458
 459                 // Functions introducing procedural macros reserve a slot
 460                 // in the macro namespace as well (see #52225).
 461                 if attr::contains_name(&item.attrs, "proc_macro") ||
 462                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 463                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 464                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 465                 }
 466                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 467                     if let Some(trait_attr) =
 468                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 469                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 470                             let sp = trait_attr.span;
 471                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 472                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 473                         }
 474                     }
 475                 }
 476             }
 477
 478             // These items live in the type namespace.
 479             ItemKind::Ty(..) => {
 480                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 481                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 482             }
 483
 484             ItemKind::Existential(_, _) => {
 485                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 486                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 487             }
 488
 489             ItemKind::Enum(ref enum_definition, _) => {
 490                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 491                 let module_kind = ModuleKind::Def(def, ident.name);
 492                 let module = self.new_module(parent,
 493                                              module_kind,
 494                                              parent.normal_ancestor_id,
 495                                              expansion,
 496                                              item.span);
 497                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 498
 499                 for variant in &(*enum_definition).variants {
 500                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 501                 }
 502             }
 503
 504             ItemKind::TraitAlias(..) => {
 505                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 506                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 507             }
 508
 509             // These items live in both the type and value namespaces.
 510             ItemKind::Struct(ref struct_def, _) => {
 511                 // Define a name in the type namespace.
 512                 let def_id = self.definitions.local_def_id(item.id);
 513                 let def = Def::Struct(def_id);
 514                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 515
 516                 let mut ctor_vis = vis;
 517
 518                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 519
 520                 // If the structure is marked as non_exhaustive then lower the visibility
 521                 // to within the crate.
 522                 if has_non_exhaustive && vis == ty::Visibility::Public {
 523                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 524                 }
 525
 526                 // Record field names for error reporting.
 527                 let field_names = struct_def.fields().iter().filter_map(|field| {
 528                     let field_vis = self.resolve_visibility(&field.vis);
 529                     if ctor_vis.is_at_least(field_vis, &*self) {
 530                         ctor_vis = field_vis;
 531                     }
 532                     field.ident.map(|ident| ident.name)
 533                 }).collect();
 534                 let item_def_id = self.definitions.local_def_id(item.id);
 535                 self.insert_field_names(item_def_id, field_names);
 536
 537                 // If this is a tuple or unit struct, define a name
 538                 // in the value namespace as well.
 539                 if !struct_def.is_struct() {
 540                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 541                                                    CtorKind::from_ast(struct_def));
 542                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 543                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 544                 }
 545             }
 546
 547             ItemKind::Union(ref vdata, _) => {
 548                 let def = Def::Union(self.definitions.local_def_id(item.id));
 549                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 550
 551                 // Record field names for error reporting.
 552                 let field_names = vdata.fields().iter().filter_map(|field| {
 553                     self.resolve_visibility(&field.vis);
 554                     field.ident.map(|ident| ident.name)
 555                 }).collect();
 556                 let item_def_id = self.definitions.local_def_id(item.id);
 557                 self.insert_field_names(item_def_id, field_names);
 558             }
 559
 560             ItemKind::Impl(..) => {}
 561
 562             ItemKind::Trait(..) => {
 563                 let def_id = self.definitions.local_def_id(item.id);
 564
 565                 // Add all the items within to a new module.
 566                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 567                 let module = self.new_module(parent,
 568                                              module_kind,
 569                                              parent.normal_ancestor_id,
 570                                              expansion,
 571                                              item.span);
 572                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 573                 self.current_module = module;
 574             }
 575
 576             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 577         }
 578     }
 579
 580     // Constructs the reduced graph for one variant. Variants exist in the
 581     // type and value namespaces.
 582     fn build_reduced_graph_for_variant(&mut self,
 583                                        variant: &Variant,
 584                                        parent: Module<'a>,
 585                                        vis: ty::Visibility,
 586                                        expansion: Mark) {
 587         let ident = variant.node.ident;
 588         let def_id = self.definitions.local_def_id(variant.node.data.id());
 589
 590         // Define a name in the type namespace.
 591         let def = Def::Variant(def_id);
 592         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 593
 594         // Define a constructor name in the value namespace.
 595         // Braced variants, unlike structs, generate unusable names in
 596         // value namespace, they are reserved for possible future use.
 597         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 598         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 599
 600         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 601     }
 602
 603     /// Constructs the reduced graph for one foreign item.
 604     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 605         let (def, ns) = match item.node {
 606             ForeignItemKind::Fn(..) => {
 607                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 608             }
 609             ForeignItemKind::Static(_, m) => {
 610                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 611             }
 612             ForeignItemKind::Ty => {
 613                 (Def::ForeignTy(self.definitions.local_def_id(item.id)), TypeNS)
 614             }
 615             ForeignItemKind::Macro(_) => unreachable!(),
 616         };
 617         let parent = self.current_module;
 618         let vis = self.resolve_visibility(&item.vis);
 619         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 620     }
 621
 622     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 623         let parent = self.current_module;
 624         if self.block_needs_anonymous_module(block) {
 625             let module = self.new_module(parent,
 626                                          ModuleKind::Block(block.id),
 627                                          parent.normal_ancestor_id,
 628                                          expansion,
 629                                          block.span);
 630             self.block_map.insert(block.id, module);
 631             self.current_module = module; // Descend into the block.
 632         }
 633     }
 634
 635     /// Builds the reduced graph for a single item in an external crate.
 636     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 637         let Export { ident, def, vis, span } = child;
 638         // FIXME: We shouldn't create the gensym here, it should come from metadata,
 639         // but metadata cannot encode gensyms currently, so we create it here.
 640         // This is only a guess, two equivalent idents may incorrectly get different gensyms here.
 641         let ident = ident.gensym_if_underscore();
 642         let def_id = def.def_id();
 643         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 644         match def {
 645             Def::Mod(..) | Def::Enum(..) => {
 646                 let module = self.new_module(parent,
 647                                              ModuleKind::Def(def, ident.name),
 648                                              def_id,
 649                                              expansion,
 650                                              span);
 651                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 652             }
 653             Def::Variant(..) | Def::TyAlias(..) | Def::ForeignTy(..) => {
 654                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 655             }
 656             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 657                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 658             }
 659             Def::StructCtor(..) => {
 660                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 661
 662                 if let Some(struct_def_id) =
 663                         self.cstore.def_key(def_id).parent
 664                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 665                     self.struct_constructors.insert(struct_def_id, (def, vis));
 666                 }
 667             }
 668             Def::Trait(..) => {
 669                 let module_kind = ModuleKind::Def(def, ident.name);
 670                 let module = self.new_module(parent,
 671                                              module_kind,
 672                                              parent.normal_ancestor_id,
 673                                              expansion,
 674                                              span);
 675                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 676
 677                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 678                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 679                     self.define(module, child.ident, ns,
 680                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 681
 682                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 683                            .method_has_self_argument {
 684                         self.has_self.insert(child.def.def_id());
 685                     }
 686                 }
 687                 module.populated.set(true);
 688             }
 689             Def::Existential(..) |
 690             Def::TraitAlias(..) => {
 691                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 692             }
 693             Def::Struct(..) | Def::Union(..) => {
 694                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 695
 696                 // Record field names for error reporting.
 697                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 698                 self.insert_field_names(def_id, field_names);
 699             }
 700             Def::Macro(..) => {
 701                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 702             }
 703             _ => bug!("unexpected definition: {:?}", def)
 704         }
 705     }
 706
 707     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 708         if def_id.krate == LOCAL_CRATE {
 709             return self.module_map[&def_id]
 710         }
 711
 712         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 713         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 714             return module;
 715         }
 716
 717         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 718             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 719         } else {
 720             let def_key = self.cstore.def_key(def_id);
 721             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 722              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 723         };
 724
 725         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 726         let module =
 727             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 728         self.extern_module_map.insert((def_id, macros_only), module);
 729         module
 730     }
 731
 732     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 733         let def_id = self.macro_defs[&expansion];
 734         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 735             self.local_macro_def_scopes[&id]
 736         } else if def_id.krate == CrateNum::BuiltinMacros {
 737             self.injected_crate.unwrap_or(self.graph_root)
 738         } else {
 739             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 740             self.get_module(module_def_id)
 741         }
 742     }
 743
 744     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 745         let def_id = match def {
 746             Def::Macro(def_id, ..) => def_id,
 747             Def::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 748                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 749             }),
 750             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 751         };
 752         if let Some(ext) = self.macro_map.get(&def_id) {
 753             return ext.clone();
 754         }
 755
 756         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 757             LoadedMacro::MacroDef(macro_def) => macro_def,
 758             LoadedMacro::ProcMacro(ext) => return ext,
 759         };
 760
 761         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 762                                                &self.session.features_untracked(),
 763                                                &macro_def,
 764                                                self.cstore.crate_edition_untracked(def_id.krate)));
 765         self.macro_map.insert(def_id, ext.clone());
 766         ext
 767     }
 768
 769     /// Ensures that the reduced graph rooted at the given external module
 770     /// is built, building it if it is not.
 771     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 772         if module.populated.get() { return }
 773         let def_id = module.def_id().unwrap();
 774         for child in self.cstore.item_children_untracked(def_id, self.session) {
 775             self.build_reduced_graph_for_external_crate_def(module, child);
 776         }
 777         module.populated.set(true)
 778     }
 779
 780     fn legacy_import_macro(&mut self,
 781                            name: Name,
 782                            binding: &'a NameBinding<'a>,
 783                            span: Span,
 784                            allow_shadowing: bool) {
 785         if self.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 786             let msg = format!("`{}` is already in scope", name);
 787             let note =
 788                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 789             self.session.struct_span_err(span, &msg).note(note).emit();
 790         }
 791     }
 792
 793     /// Returns `true` if we should consider the underlying `extern crate` to be used.
 794     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>,
 795                                     parent_scope: &ParentScope<'a>) -> bool {
 796         let mut import_all = None;
 797         let mut single_imports = Vec::new();
 798         for attr in &item.attrs {
 799             if attr.check_name("macro_use") {
 800                 if self.current_module.parent.is_some() {
 801                     span_err!(self.session, item.span, E0468,
 802                         "an `extern crate` loading macros must be at the crate root");
 803                 }
 804                 if let ItemKind::ExternCrate(Some(orig_name)) = item.node {
 805                     if orig_name == keywords::SelfLower.name() {
 806                         self.session.span_err(attr.span,
 807                             "`macro_use` is not supported on `extern crate self`");
 808                     }
 809                 }
 810                 let ill_formed = |span| span_err!(self.session, span, E0466, "bad macro import");
 811                 match attr.meta() {
 812                     Some(meta) => match meta.node {
 813                         MetaItemKind::Word => {
 814                             import_all = Some(meta.span);
 815                             break;
 816                         }
 817                         MetaItemKind::List(nested_metas) => for nested_meta in nested_metas {
 818                             match nested_meta.word() {
 819                                 Some(word) => single_imports.push((word.name(), word.span)),
 820                                 None => ill_formed(nested_meta.span),
 821                             }
 822                         }
 823                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 824                     }
 825                     None => ill_formed(attr.span()),
 826                 }
 827             }
 828         }
 829
 830         let arenas = self.arenas;
 831         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 832             root_id: item.id,
 833             id: item.id,
 834             parent_scope: parent_scope.clone(),
 835             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 836             subclass: ImportDirectiveSubclass::MacroUse,
 837             use_span_with_attributes: item.span_with_attributes(),
 838             has_attributes: !item.attrs.is_empty(),
 839             use_span: item.span,
 840             root_span: span,
 841             span,
 842             module_path: Vec::new(),
 843             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 844             used: Cell::new(false),
 845         });
 846
 847         let allow_shadowing = parent_scope.expansion == Mark::root();
 848         if let Some(span) = import_all {
 849             let directive = macro_use_directive(span);
 850             self.potentially_unused_imports.push(directive);
 851             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 852                 let imported_binding = self.import(binding, directive);
 853                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 854             });
 855         } else {
 856             for (name, span) in single_imports.iter().cloned() {
 857                 let ident = Ident::with_empty_ctxt(name);
 858                 let result = self.resolve_ident_in_module(
 859                     ModuleOrUniformRoot::Module(module),
 860                     ident,
 861                     MacroNS,
 862                     None,
 863                     false,
 864                     span,
 865                 );
 866                 if let Ok(binding) = result {
 867                     let directive = macro_use_directive(span);
 868                     self.potentially_unused_imports.push(directive);
 869                     let imported_binding = self.import(binding, directive);
 870                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 871                 } else {
 872                     span_err!(self.session, span, E0469, "imported macro not found");
 873                 }
 874             }
 875         }
 876         import_all.is_some() || !single_imports.is_empty()
 877     }
 878
 879     /// Returns `true` if this attribute list contains `macro_use`.
 880     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 881         for attr in attrs {
 882             if attr.check_name("macro_escape") {
 883                 let msg = "macro_escape is a deprecated synonym for macro_use";
 884                 let mut err = self.session.struct_span_warn(attr.span, msg);
 885                 if let ast::AttrStyle::Inner = attr.style {
 886                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 887                 } else {
 888                     err.emit();
 889                 }
 890             } else if !attr.check_name("macro_use") {
 891                 continue;
 892             }
 893
 894             if !attr.is_word() {
 895                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 896             }
 897             return true;
 898         }
 899
 900         false
 901     }
 902 }
 903
 904 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 905     pub resolver: &'a mut Resolver<'b>,
 906     pub current_legacy_scope: LegacyScope<'b>,
 907     pub expansion: Mark,
 908 }
 909
 910 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 911     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 912         let mark = id.placeholder_to_mark();
 913         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 914         let invocation = self.resolver.invocations[&mark];
 915         invocation.module.set(self.resolver.current_module);
 916         invocation.parent_legacy_scope.set(self.current_legacy_scope);
 917         invocation
 918     }
 919 }
 920
 921 macro_rules! method {
 922     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 923         fn $visit(&mut self, node: &'a $ty) {
 924             if let $invoc(..) = node.node {
 925                 self.visit_invoc(node.id);
 926             } else {
 927                 visit::$walk(self, node);
 928             }
 929         }
 930     }
 931 }
 932
 933 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 934     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 935     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 936     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 937     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 938
 939     fn visit_item(&mut self, item: &'a Item) {
 940         let macro_use = match item.node {
 941             ItemKind::MacroDef(..) => {
 942                 self.resolver.define_macro(item, self.expansion, &mut self.current_legacy_scope);
 943                 return
 944             }
 945             ItemKind::Mac(..) => {
 946                 self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(item.id));
 947                 return
 948             }
 949             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 950             _ => false,
 951         };
 952
 953         let orig_current_module = self.resolver.current_module;
 954         let orig_current_legacy_scope = self.current_legacy_scope;
 955         let parent_scope = ParentScope {
 956             module: self.resolver.current_module,
 957             expansion: self.expansion,
 958             legacy: self.current_legacy_scope,
 959             derives: Vec::new(),
 960         };
 961         self.resolver.build_reduced_graph_for_item(item, parent_scope);
 962         visit::walk_item(self, item);
 963         self.resolver.current_module = orig_current_module;
 964         if !macro_use {
 965             self.current_legacy_scope = orig_current_legacy_scope;
 966         }
 967     }
 968
 969     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 970         if let ast::StmtKind::Mac(..) = stmt.node {
 971             self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(stmt.id));
 972         } else {
 973             visit::walk_stmt(self, stmt);
 974         }
 975     }
 976
 977     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 978         if let ForeignItemKind::Macro(_) = foreign_item.node {
 979             self.visit_invoc(foreign_item.id);
 980             return;
 981         }
 982
 983         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 984         visit::walk_foreign_item(self, foreign_item);
 985     }
 986
 987     fn visit_block(&mut self, block: &'a Block) {
 988         let orig_current_module = self.resolver.current_module;
 989         let orig_current_legacy_scope = self.current_legacy_scope;
 990         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 991         visit::walk_block(self, block);
 992         self.resolver.current_module = orig_current_module;
 993         self.current_legacy_scope = orig_current_legacy_scope;
 994     }
 995
 996     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 997         let parent = self.resolver.current_module;
 998
 999         if let TraitItemKind::Macro(_) = item.node {
1000             self.visit_invoc(item.id);
1001             return
1002         }
1003
1004         // Add the item to the trait info.
1005         let item_def_id = self.resolver.definitions.local_def_id(item.id);
1006         let (def, ns) = match item.node {
1007             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
1008             TraitItemKind::Method(ref sig, _) => {
1009                 if sig.decl.has_self() {
1010                     self.resolver.has_self.insert(item_def_id);
1011                 }
1012                 (Def::Method(item_def_id), ValueNS)
1013             }
1014             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
1015             TraitItemKind::Macro(_) => bug!(),  // handled above
1016         };
1017
1018         let vis = ty::Visibility::Public;
1019         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
1020
1021         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
1022         visit::walk_trait_item(self, item);
1023         self.resolver.current_module = parent;
1024     }
1025
1026     fn visit_token(&mut self, t: Token) {
1027         if let Token::Interpolated(nt) = t {
1028             if let token::NtExpr(ref expr) = nt.0 {
1029                 if let ast::ExprKind::Mac(..) = expr.node {
1030                     self.visit_invoc(expr.id);
1031                 }
1032             }
1033         }
1034     }
1035
1036     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
1037         if !attr.is_sugared_doc && is_builtin_attr(attr) {
1038             let parent_scope = ParentScope {
1039                 module: self.resolver.current_module.nearest_item_scope(),
1040                 expansion: self.expansion,
1041                 legacy: self.current_legacy_scope,
1042                 // Let's hope discerning built-in attributes from derive helpers is not necessary
1043                 derives: Vec::new(),
1044             };
1045             parent_scope.module.builtin_attrs.borrow_mut().push((
1046                 attr.path.segments[0].ident, parent_scope
1047             ));
1048         }
1049         visit::walk_attribute(self, attr);
1050     }
1051 }