src/librustc_resolve/build_reduced_graph.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Reduced graph building
  12 //!
  13 //! Here we build the "reduced graph": the graph of the module tree without
  14 //! any imports resolved.
  15
  16 use macros::{InvocationData, ParentScope, LegacyScope};
  17 use resolve_imports::ImportDirective;
  18 use resolve_imports::ImportDirectiveSubclass::{self, GlobImport, SingleImport};
  19 use {Module, ModuleData, ModuleKind, NameBinding, NameBindingKind, Segment, ToNameBinding};
  20 use {ModuleOrUniformRoot, PerNS, Resolver, ResolverArenas, ExternPreludeEntry};
  21 use Namespace::{self, TypeNS, ValueNS, MacroNS};
  22 use {resolve_error, resolve_struct_error, ResolutionError};
  23
  24 use rustc::hir::def::*;
  25 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  26 use rustc::ty;
  27 use rustc::middle::cstore::CrateStore;
  28 use rustc_metadata::cstore::LoadedMacro;
  29
  30 use std::cell::Cell;
  31 use std::ptr;
  32 use rustc_data_structures::sync::Lrc;
  33
  34 use syntax::ast::{Name, Ident};
  35 use syntax::attr;
  36
  37 use syntax::ast::{self, Block, ForeignItem, ForeignItemKind, Item, ItemKind, NodeId};
  38 use syntax::ast::{MetaItemKind, Mutability, StmtKind, TraitItem, TraitItemKind, Variant};
  39 use syntax::ext::base::{MacroKind, SyntaxExtension};
  40 use syntax::ext::base::Determinacy::Undetermined;
  41 use syntax::ext::hygiene::Mark;
  42 use syntax::ext::tt::macro_rules;
  43 use syntax::feature_gate::is_builtin_attr;
  44 use syntax::parse::token::{self, Token};
  45 use syntax::std_inject::injected_crate_name;
  46 use syntax::symbol::keywords;
  47 use syntax::visit::{self, Visitor};
  48
  49 use syntax_pos::{Span, DUMMY_SP};
  50
  51 impl<'a> ToNameBinding<'a> for (Module<'a>, ty::Visibility, Span, Mark) {
  52     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  53         arenas.alloc_name_binding(NameBinding {
  54             kind: NameBindingKind::Module(self.0),
  55             vis: self.1,
  56             span: self.2,
  57             expansion: self.3,
  58         })
  59     }
  60 }
  61
  62 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
  63     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  64         arenas.alloc_name_binding(NameBinding {
  65             kind: NameBindingKind::Def(self.0, false),
  66             vis: self.1,
  67             span: self.2,
  68             expansion: self.3,
  69         })
  70     }
  71 }
  72
  73 pub(crate) struct IsMacroExport;
  74
  75 impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark, IsMacroExport) {
  76     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
  77         arenas.alloc_name_binding(NameBinding {
  78             kind: NameBindingKind::Def(self.0, true),
  79             vis: self.1,
  80             span: self.2,
  81             expansion: self.3,
  82         })
  83     }
  84 }
  85
  86 impl<'a, 'cl> Resolver<'a, 'cl> {
  87     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  88     /// otherwise, reports an error.
  89     pub fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespace, def: T)
  90         where T: ToNameBinding<'a>,
  91     {
  92         let binding = def.to_name_binding(self.arenas);
  93         if let Err(old_binding) = self.try_define(parent, ident, ns, binding) {
  94             self.report_conflict(parent, ident, ns, old_binding, &binding);
  95         }
  96     }
  97
  98     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  99         // If any statements are items, we need to create an anonymous module
 100         block.stmts.iter().any(|statement| match statement.node {
 101             StmtKind::Item(_) | StmtKind::Mac(_) => true,
 102             _ => false,
 103         })
 104     }
 105
 106     fn insert_field_names(&mut self, def_id: DefId, field_names: Vec<Name>) {
 107         if !field_names.is_empty() {
 108             self.field_names.insert(def_id, field_names);
 109         }
 110     }
 111
 112     fn build_reduced_graph_for_use_tree(
 113         &mut self,
 114         // This particular use tree
 115         use_tree: &ast::UseTree,
 116         id: NodeId,
 117         parent_prefix: &[Segment],
 118         nested: bool,
 119         // The whole `use` item
 120         parent_scope: ParentScope<'a>,
 121         item: &Item,
 122         vis: ty::Visibility,
 123         root_span: Span,
 124     ) {
 125         debug!("build_reduced_graph_for_use_tree(parent_prefix={:?}, use_tree={:?}, nested={})",
 126                parent_prefix, use_tree, nested);
 127
 128         let mut prefix_iter = parent_prefix.iter().cloned()
 129             .chain(use_tree.prefix.segments.iter().map(|seg| seg.into())).peekable();
 130
 131         // On 2015 edition imports are resolved as crate-relative by default,
 132         // so prefixes are prepended with crate root segment if necessary.
 133         // The root is prepended lazily, when the first non-empty prefix or terminating glob
 134         // appears, so imports in braced groups can have roots prepended independently.
 135         // 2015 identifiers used on global 2018 edition enter special "virtual 2015 mode", don't
 136         // get crate root prepended, but get special treatment during in-scope resolution instead.
 137         let is_glob = if let ast::UseTreeKind::Glob = use_tree.kind { true } else { false };
 138         let crate_root = match prefix_iter.peek() {
 139             Some(seg) if !seg.ident.is_path_segment_keyword() &&
 140                          seg.ident.span.rust_2015() && self.session.rust_2015() => {
 141                 Some(seg.ident.span.ctxt())
 142             }
 143             None if is_glob && use_tree.span.rust_2015() => {
 144                 Some(use_tree.span.ctxt())
 145             }
 146             _ => None,
 147         }.map(|ctxt| Segment::from_ident(Ident::new(
 148             keywords::CrateRoot.name(), use_tree.prefix.span.shrink_to_lo().with_ctxt(ctxt)
 149         )));
 150
 151         let prefix = crate_root.into_iter().chain(prefix_iter).collect::<Vec<_>>();
 152         debug!("build_reduced_graph_for_use_tree: prefix={:?}", prefix);
 153
 154         let empty_for_self = |prefix: &[Segment]| {
 155             prefix.is_empty() ||
 156                 prefix.len() == 1 && prefix[0].ident.name == keywords::CrateRoot.name()
 157         };
 158         match use_tree.kind {
 159             ast::UseTreeKind::Simple(rename, ..) => {
 160                 let mut ident = use_tree.ident();
 161                 let mut module_path = prefix;
 162                 let mut source = module_path.pop().unwrap();
 163                 let mut type_ns_only = false;
 164
 165                 if nested {
 166                     // Correctly handle `self`
 167                     if source.ident.name == keywords::SelfValue.name() {
 168                         type_ns_only = true;
 169
 170                         if empty_for_self(&module_path) {
 171                             resolve_error(
 172                                 self,
 173                                 use_tree.span,
 174                                 ResolutionError::
 175                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 176                             );
 177                             return;
 178                         }
 179
 180                         // Replace `use foo::self;` with `use foo;`
 181                         source = module_path.pop().unwrap();
 182                         if rename.is_none() {
 183                             ident = source.ident;
 184                         }
 185                     }
 186                 } else {
 187                     // Disallow `self`
 188                     if source.ident.name == keywords::SelfValue.name() {
 189                         resolve_error(self,
 190                                       use_tree.span,
 191                                       ResolutionError::SelfImportsOnlyAllowedWithin);
 192                     }
 193
 194                     // Disallow `use $crate;`
 195                     if source.ident.name == keywords::DollarCrate.name() && module_path.is_empty() {
 196                         let crate_root = self.resolve_crate_root(source.ident);
 197                         let crate_name = match crate_root.kind {
 198                             ModuleKind::Def(_, name) => name,
 199                             ModuleKind::Block(..) => unreachable!(),
 200                         };
 201                         // HACK(eddyb) unclear how good this is, but keeping `$crate`
 202                         // in `source` breaks `src/test/compile-fail/import-crate-var.rs`,
 203                         // while the current crate doesn't have a valid `crate_name`.
 204                         if crate_name != keywords::Invalid.name() {
 205                             // `crate_name` should not be interpreted as relative.
 206                             module_path.push(Segment {
 207                                 ident: Ident {
 208                                     name: keywords::CrateRoot.name(),
 209                                     span: source.ident.span,
 210                                 },
 211                                 id: Some(self.session.next_node_id()),
 212                             });
 213                             source.ident.name = crate_name;
 214                         }
 215                         if rename.is_none() {
 216                             ident.name = crate_name;
 217                         }
 218
 219                         self.session.struct_span_warn(item.span, "`$crate` may not be imported")
 220                             .note("`use $crate;` was erroneously allowed and \
 221                                    will become a hard error in a future release")
 222                             .emit();
 223                     }
 224                 }
 225
 226                 if ident.name == keywords::Crate.name() {
 227                     self.session.span_err(ident.span,
 228                         "crate root imports need to be explicitly named: \
 229                          `use crate as name;`");
 230                 }
 231
 232                 let subclass = SingleImport {
 233                     target: ident,
 234                     source: source.ident,
 235                     result: PerNS {
 236                         type_ns: Cell::new(Err(Undetermined)),
 237                         value_ns: Cell::new(Err(Undetermined)),
 238                         macro_ns: Cell::new(Err(Undetermined)),
 239                     },
 240                     type_ns_only,
 241                 };
 242                 self.add_import_directive(
 243                     module_path,
 244                     subclass,
 245                     use_tree.span,
 246                     id,
 247                     root_span,
 248                     item.id,
 249                     vis,
 250                     parent_scope,
 251                 );
 252             }
 253             ast::UseTreeKind::Glob => {
 254                 let subclass = GlobImport {
 255                     is_prelude: attr::contains_name(&item.attrs, "prelude_import"),
 256                     max_vis: Cell::new(ty::Visibility::Invisible),
 257                 };
 258                 self.add_import_directive(
 259                     prefix,
 260                     subclass,
 261                     use_tree.span,
 262                     id,
 263                     root_span,
 264                     item.id,
 265                     vis,
 266                     parent_scope,
 267                 );
 268             }
 269             ast::UseTreeKind::Nested(ref items) => {
 270                 // Ensure there is at most one `self` in the list
 271                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 272                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 273                         if use_tree.ident().name == keywords::SelfValue.name() {
 274                             return Some(use_tree.span);
 275                         }
 276                     }
 277
 278                     None
 279                 }).collect::<Vec<_>>();
 280                 if self_spans.len() > 1 {
 281                     let mut e = resolve_struct_error(self,
 282                         self_spans[0],
 283                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 284
 285                     for other_span in self_spans.iter().skip(1) {
 286                         e.span_label(*other_span, "another `self` import appears here");
 287                     }
 288
 289                     e.emit();
 290                 }
 291
 292                 for &(ref tree, id) in items {
 293                     self.build_reduced_graph_for_use_tree(
 294                         // This particular use tree
 295                         tree, id, &prefix, true,
 296                         // The whole `use` item
 297                         parent_scope.clone(), item, vis, root_span,
 298                     );
 299                 }
 300
 301                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 302                 // `a::b::c::{self as _}`, so that their prefixes are correctly
 303                 // resolved and checked for privacy/stability/etc.
 304                 if items.is_empty() && !empty_for_self(&prefix) {
 305                     let new_span = prefix[prefix.len() - 1].ident.span;
 306                     let tree = ast::UseTree {
 307                         prefix: ast::Path::from_ident(
 308                             Ident::new(keywords::SelfValue.name(), new_span)
 309                         ),
 310                         kind: ast::UseTreeKind::Simple(
 311                             Some(Ident::new(keywords::Underscore.name().gensymed(), new_span)),
 312                             ast::DUMMY_NODE_ID,
 313                             ast::DUMMY_NODE_ID,
 314                         ),
 315                         span: use_tree.span,
 316                     };
 317                     self.build_reduced_graph_for_use_tree(
 318                         // This particular use tree
 319                         &tree, id, &prefix, true,
 320                         // The whole `use` item
 321                         parent_scope.clone(), item, ty::Visibility::Invisible, root_span,
 322                     );
 323                 }
 324             }
 325         }
 326     }
 327
 328     /// Constructs the reduced graph for one item.
 329     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_scope: ParentScope<'a>) {
 330         let parent = parent_scope.module;
 331         let expansion = parent_scope.expansion;
 332         let ident = item.ident;
 333         let sp = item.span;
 334         let vis = self.resolve_visibility(&item.vis);
 335
 336         match item.node {
 337             ItemKind::Use(ref use_tree) => {
 338                 self.build_reduced_graph_for_use_tree(
 339                     // This particular use tree
 340                     use_tree, item.id, &[], false,
 341                     // The whole `use` item
 342                     parent_scope, item, vis, use_tree.span,
 343                 );
 344             }
 345
 346             ItemKind::ExternCrate(orig_name) => {
 347                 let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 348                 let module =
 349                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
 350                 self.populate_module_if_necessary(module);
 351                 if injected_crate_name().map_or(false, |name| ident.name == name) {
 352                     self.injected_crate = Some(module);
 353                 }
 354
 355                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
 356                 let binding =
 357                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 358                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 359                     root_id: item.id,
 360                     id: item.id,
 361                     parent_scope,
 362                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 363                     subclass: ImportDirectiveSubclass::ExternCrate {
 364                         source: orig_name,
 365                         target: ident,
 366                     },
 367                     root_span: item.span,
 368                     span: item.span,
 369                     module_path: Vec::new(),
 370                     vis: Cell::new(vis),
 371                     used: Cell::new(used),
 372                 });
 373                 self.potentially_unused_imports.push(directive);
 374                 let imported_binding = self.import(binding, directive);
 375                 if ptr::eq(self.current_module, self.graph_root) {
 376                     if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
 377                         if expansion != Mark::root() && orig_name.is_some() &&
 378                            entry.extern_crate_item.is_none() {
 379                             self.session.span_err(item.span, "macro-expanded `extern crate` items \
 380                                                               cannot shadow names passed with \
 381                                                               `--extern`");
 382                         }
 383                     }
 384                     let entry = self.extern_prelude.entry(ident.modern())
 385                                                    .or_insert(ExternPreludeEntry {
 386                         extern_crate_item: None,
 387                         introduced_by_item: true,
 388                     });
 389                     entry.extern_crate_item = Some(imported_binding);
 390                     if orig_name.is_some() {
 391                         entry.introduced_by_item = true;
 392                     }
 393                 }
 394                 self.define(parent, ident, TypeNS, imported_binding);
 395             }
 396
 397             ItemKind::GlobalAsm(..) => {}
 398
 399             ItemKind::Mod(..) if ident == keywords::Invalid.ident() => {} // Crate root
 400
 401             ItemKind::Mod(..) => {
 402                 let def_id = self.definitions.local_def_id(item.id);
 403                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 404                 let module = self.arenas.alloc_module(ModuleData {
 405                     no_implicit_prelude: parent.no_implicit_prelude || {
 406                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 407                     },
 408                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 409                 });
 410                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 411                 self.module_map.insert(def_id, module);
 412
 413                 // Descend into the module.
 414                 self.current_module = module;
 415             }
 416
 417             // Handled in `rustc_metadata::{native_libs,link_args}`
 418             ItemKind::ForeignMod(..) => {}
 419
 420             // These items live in the value namespace.
 421             ItemKind::Static(_, m, _) => {
 422                 let mutbl = m == Mutability::Mutable;
 423                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 424                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 425             }
 426             ItemKind::Const(..) => {
 427                 let def = Def::Const(self.definitions.local_def_id(item.id));
 428                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 429             }
 430             ItemKind::Fn(..) => {
 431                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 432                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 433
 434                 // Functions introducing procedural macros reserve a slot
 435                 // in the macro namespace as well (see #52225).
 436                 if attr::contains_name(&item.attrs, "proc_macro") ||
 437                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 438                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 439                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 440                 }
 441                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 442                     if let Some(trait_attr) =
 443                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 444                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 445                             let sp = trait_attr.span;
 446                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 447                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 448                         }
 449                     }
 450                 }
 451             }
 452
 453             // These items live in the type namespace.
 454             ItemKind::Ty(..) => {
 455                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 456                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 457             }
 458
 459             ItemKind::Existential(_, _) => {
 460                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 461                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 462             }
 463
 464             ItemKind::Enum(ref enum_definition, _) => {
 465                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 466                 let module_kind = ModuleKind::Def(def, ident.name);
 467                 let module = self.new_module(parent,
 468                                              module_kind,
 469                                              parent.normal_ancestor_id,
 470                                              expansion,
 471                                              item.span);
 472                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 473
 474                 for variant in &(*enum_definition).variants {
 475                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 476                 }
 477             }
 478
 479             ItemKind::TraitAlias(..) => {
 480                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 481                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 482             }
 483
 484             // These items live in both the type and value namespaces.
 485             ItemKind::Struct(ref struct_def, _) => {
 486                 // Define a name in the type namespace.
 487                 let def_id = self.definitions.local_def_id(item.id);
 488                 let def = Def::Struct(def_id);
 489                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 490
 491                 let mut ctor_vis = vis;
 492
 493                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 494
 495                 // If the structure is marked as non_exhaustive then lower the visibility
 496                 // to within the crate.
 497                 if has_non_exhaustive && vis == ty::Visibility::Public {
 498                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 499                 }
 500
 501                 // Record field names for error reporting.
 502                 let field_names = struct_def.fields().iter().filter_map(|field| {
 503                     let field_vis = self.resolve_visibility(&field.vis);
 504                     if ctor_vis.is_at_least(field_vis, &*self) {
 505                         ctor_vis = field_vis;
 506                     }
 507                     field.ident.map(|ident| ident.name)
 508                 }).collect();
 509                 let item_def_id = self.definitions.local_def_id(item.id);
 510                 self.insert_field_names(item_def_id, field_names);
 511
 512                 // If this is a tuple or unit struct, define a name
 513                 // in the value namespace as well.
 514                 if !struct_def.is_struct() {
 515                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 516                                                    CtorKind::from_ast(struct_def));
 517                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 518                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 519                 }
 520             }
 521
 522             ItemKind::Union(ref vdata, _) => {
 523                 let def = Def::Union(self.definitions.local_def_id(item.id));
 524                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 525
 526                 // Record field names for error reporting.
 527                 let field_names = vdata.fields().iter().filter_map(|field| {
 528                     self.resolve_visibility(&field.vis);
 529                     field.ident.map(|ident| ident.name)
 530                 }).collect();
 531                 let item_def_id = self.definitions.local_def_id(item.id);
 532                 self.insert_field_names(item_def_id, field_names);
 533             }
 534
 535             ItemKind::Impl(..) => {}
 536
 537             ItemKind::Trait(..) => {
 538                 let def_id = self.definitions.local_def_id(item.id);
 539
 540                 // Add all the items within to a new module.
 541                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 542                 let module = self.new_module(parent,
 543                                              module_kind,
 544                                              parent.normal_ancestor_id,
 545                                              expansion,
 546                                              item.span);
 547                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 548                 self.current_module = module;
 549             }
 550
 551             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 552         }
 553     }
 554
 555     // Constructs the reduced graph for one variant. Variants exist in the
 556     // type and value namespaces.
 557     fn build_reduced_graph_for_variant(&mut self,
 558                                        variant: &Variant,
 559                                        parent: Module<'a>,
 560                                        vis: ty::Visibility,
 561                                        expansion: Mark) {
 562         let ident = variant.node.ident;
 563         let def_id = self.definitions.local_def_id(variant.node.data.id());
 564
 565         // Define a name in the type namespace.
 566         let def = Def::Variant(def_id);
 567         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 568
 569         // Define a constructor name in the value namespace.
 570         // Braced variants, unlike structs, generate unusable names in
 571         // value namespace, they are reserved for possible future use.
 572         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 573         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 574
 575         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 576     }
 577
 578     /// Constructs the reduced graph for one foreign item.
 579     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 580         let (def, ns) = match item.node {
 581             ForeignItemKind::Fn(..) => {
 582                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 583             }
 584             ForeignItemKind::Static(_, m) => {
 585                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 586             }
 587             ForeignItemKind::Ty => {
 588                 (Def::ForeignTy(self.definitions.local_def_id(item.id)), TypeNS)
 589             }
 590             ForeignItemKind::Macro(_) => unreachable!(),
 591         };
 592         let parent = self.current_module;
 593         let vis = self.resolve_visibility(&item.vis);
 594         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 595     }
 596
 597     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 598         let parent = self.current_module;
 599         if self.block_needs_anonymous_module(block) {
 600             let module = self.new_module(parent,
 601                                          ModuleKind::Block(block.id),
 602                                          parent.normal_ancestor_id,
 603                                          expansion,
 604                                          block.span);
 605             self.block_map.insert(block.id, module);
 606             self.current_module = module; // Descend into the block.
 607         }
 608     }
 609
 610     /// Builds the reduced graph for a single item in an external crate.
 611     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 612         let Export { ident, def, vis, span, .. } = child;
 613         let def_id = def.def_id();
 614         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 615         match def {
 616             Def::Mod(..) | Def::Enum(..) => {
 617                 let module = self.new_module(parent,
 618                                              ModuleKind::Def(def, ident.name),
 619                                              def_id,
 620                                              expansion,
 621                                              span);
 622                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 623             }
 624             Def::Variant(..) | Def::TyAlias(..) | Def::ForeignTy(..) => {
 625                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 626             }
 627             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 628                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 629             }
 630             Def::StructCtor(..) => {
 631                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 632
 633                 if let Some(struct_def_id) =
 634                         self.cstore.def_key(def_id).parent
 635                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 636                     self.struct_constructors.insert(struct_def_id, (def, vis));
 637                 }
 638             }
 639             Def::Trait(..) => {
 640                 let module_kind = ModuleKind::Def(def, ident.name);
 641                 let module = self.new_module(parent,
 642                                              module_kind,
 643                                              parent.normal_ancestor_id,
 644                                              expansion,
 645                                              span);
 646                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 647
 648                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 649                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 650                     self.define(module, child.ident, ns,
 651                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 652
 653                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 654                            .method_has_self_argument {
 655                         self.has_self.insert(child.def.def_id());
 656                     }
 657                 }
 658                 module.populated.set(true);
 659             }
 660             Def::Struct(..) | Def::Union(..) => {
 661                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 662
 663                 // Record field names for error reporting.
 664                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 665                 self.insert_field_names(def_id, field_names);
 666             }
 667             Def::Macro(..) => {
 668                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 669             }
 670             _ => bug!("unexpected definition: {:?}", def)
 671         }
 672     }
 673
 674     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 675         if def_id.krate == LOCAL_CRATE {
 676             return self.module_map[&def_id]
 677         }
 678
 679         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 680         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 681             return module;
 682         }
 683
 684         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 685             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 686         } else {
 687             let def_key = self.cstore.def_key(def_id);
 688             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 689              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 690         };
 691
 692         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 693         let module =
 694             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 695         self.extern_module_map.insert((def_id, macros_only), module);
 696         module
 697     }
 698
 699     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 700         let def_id = self.macro_defs[&expansion];
 701         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 702             self.local_macro_def_scopes[&id]
 703         } else if def_id.krate == CrateNum::BuiltinMacros {
 704             self.injected_crate.unwrap_or(self.graph_root)
 705         } else {
 706             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 707             self.get_module(module_def_id)
 708         }
 709     }
 710
 711     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 712         let def_id = match def {
 713             Def::Macro(def_id, ..) => def_id,
 714             Def::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 715                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 716             }),
 717             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 718         };
 719         if let Some(ext) = self.macro_map.get(&def_id) {
 720             return ext.clone();
 721         }
 722
 723         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 724             LoadedMacro::MacroDef(macro_def) => macro_def,
 725             LoadedMacro::ProcMacro(ext) => return ext,
 726         };
 727
 728         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 729                                                &self.session.features_untracked(),
 730                                                &macro_def,
 731                                                self.cstore.crate_edition_untracked(def_id.krate)));
 732         self.macro_map.insert(def_id, ext.clone());
 733         ext
 734     }
 735
 736     /// Ensures that the reduced graph rooted at the given external module
 737     /// is built, building it if it is not.
 738     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 739         if module.populated.get() { return }
 740         let def_id = module.def_id().unwrap();
 741         for child in self.cstore.item_children_untracked(def_id, self.session) {
 742             self.build_reduced_graph_for_external_crate_def(module, child);
 743         }
 744         module.populated.set(true)
 745     }
 746
 747     fn legacy_import_macro(&mut self,
 748                            name: Name,
 749                            binding: &'a NameBinding<'a>,
 750                            span: Span,
 751                            allow_shadowing: bool) {
 752         if self.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 753             let msg = format!("`{}` is already in scope", name);
 754             let note =
 755                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 756             self.session.struct_span_err(span, &msg).note(note).emit();
 757         }
 758     }
 759
 760     // This returns true if we should consider the underlying `extern crate` to be used.
 761     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>,
 762                                     parent_scope: &ParentScope<'a>) -> bool {
 763         let mut import_all = None;
 764         let mut single_imports = Vec::new();
 765         for attr in &item.attrs {
 766             if attr.check_name("macro_use") {
 767                 if self.current_module.parent.is_some() {
 768                     span_err!(self.session, item.span, E0468,
 769                         "an `extern crate` loading macros must be at the crate root");
 770                 }
 771                 let ill_formed = |span| span_err!(self.session, span, E0466, "bad macro import");
 772                 match attr.meta() {
 773                     Some(meta) => match meta.node {
 774                         MetaItemKind::Word => {
 775                             import_all = Some(meta.span);
 776                             break;
 777                         }
 778                         MetaItemKind::List(nested_metas) => for nested_meta in nested_metas {
 779                             match nested_meta.word() {
 780                                 Some(word) => single_imports.push((word.name(), word.span)),
 781                                 None => ill_formed(nested_meta.span),
 782                             }
 783                         }
 784                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 785                     }
 786                     None => ill_formed(attr.span()),
 787                 }
 788             }
 789         }
 790
 791         let arenas = self.arenas;
 792         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 793             root_id: item.id,
 794             id: item.id,
 795             parent_scope: parent_scope.clone(),
 796             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 797             subclass: ImportDirectiveSubclass::MacroUse,
 798             root_span: span,
 799             span,
 800             module_path: Vec::new(),
 801             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 802             used: Cell::new(false),
 803         });
 804
 805         let allow_shadowing = parent_scope.expansion == Mark::root();
 806         if let Some(span) = import_all {
 807             let directive = macro_use_directive(span);
 808             self.potentially_unused_imports.push(directive);
 809             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 810                 let imported_binding = self.import(binding, directive);
 811                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 812             });
 813         } else {
 814             for (name, span) in single_imports.iter().cloned() {
 815                 let ident = Ident::with_empty_ctxt(name);
 816                 let result = self.resolve_ident_in_module(
 817                     ModuleOrUniformRoot::Module(module),
 818                     ident,
 819                     MacroNS,
 820                     None,
 821                     false,
 822                     span,
 823                 );
 824                 if let Ok(binding) = result {
 825                     let directive = macro_use_directive(span);
 826                     self.potentially_unused_imports.push(directive);
 827                     let imported_binding = self.import(binding, directive);
 828                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 829                 } else {
 830                     span_err!(self.session, span, E0469, "imported macro not found");
 831                 }
 832             }
 833         }
 834         import_all.is_some() || !single_imports.is_empty()
 835     }
 836
 837     // does this attribute list contain "macro_use"?
 838     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 839         for attr in attrs {
 840             if attr.check_name("macro_escape") {
 841                 let msg = "macro_escape is a deprecated synonym for macro_use";
 842                 let mut err = self.session.struct_span_warn(attr.span, msg);
 843                 if let ast::AttrStyle::Inner = attr.style {
 844                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 845                 } else {
 846                     err.emit();
 847                 }
 848             } else if !attr.check_name("macro_use") {
 849                 continue;
 850             }
 851
 852             if !attr.is_word() {
 853                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 854             }
 855             return true;
 856         }
 857
 858         false
 859     }
 860 }
 861
 862 pub struct BuildReducedGraphVisitor<'a, 'b: 'a, 'c: 'b> {
 863     pub resolver: &'a mut Resolver<'b, 'c>,
 864     pub current_legacy_scope: LegacyScope<'b>,
 865     pub expansion: Mark,
 866 }
 867
 868 impl<'a, 'b, 'cl> BuildReducedGraphVisitor<'a, 'b, 'cl> {
 869     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 870         let mark = id.placeholder_to_mark();
 871         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 872         let invocation = self.resolver.invocations[&mark];
 873         invocation.module.set(self.resolver.current_module);
 874         invocation.parent_legacy_scope.set(self.current_legacy_scope);
 875         invocation
 876     }
 877 }
 878
 879 macro_rules! method {
 880     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 881         fn $visit(&mut self, node: &'a $ty) {
 882             if let $invoc(..) = node.node {
 883                 self.visit_invoc(node.id);
 884             } else {
 885                 visit::$walk(self, node);
 886             }
 887         }
 888     }
 889 }
 890
 891 impl<'a, 'b, 'cl> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b, 'cl> {
 892     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 893     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 894     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 895     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 896
 897     fn visit_item(&mut self, item: &'a Item) {
 898         let macro_use = match item.node {
 899             ItemKind::MacroDef(..) => {
 900                 self.resolver.define_macro(item, self.expansion, &mut self.current_legacy_scope);
 901                 return
 902             }
 903             ItemKind::Mac(..) => {
 904                 self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(item.id));
 905                 return
 906             }
 907             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 908             _ => false,
 909         };
 910
 911         let orig_current_module = self.resolver.current_module;
 912         let orig_current_legacy_scope = self.current_legacy_scope;
 913         let parent_scope = ParentScope {
 914             module: self.resolver.current_module,
 915             expansion: self.expansion,
 916             legacy: self.current_legacy_scope,
 917             derives: Vec::new(),
 918         };
 919         self.resolver.build_reduced_graph_for_item(item, parent_scope);
 920         visit::walk_item(self, item);
 921         self.resolver.current_module = orig_current_module;
 922         if !macro_use {
 923             self.current_legacy_scope = orig_current_legacy_scope;
 924         }
 925     }
 926
 927     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 928         if let ast::StmtKind::Mac(..) = stmt.node {
 929             self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(stmt.id));
 930         } else {
 931             visit::walk_stmt(self, stmt);
 932         }
 933     }
 934
 935     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 936         if let ForeignItemKind::Macro(_) = foreign_item.node {
 937             self.visit_invoc(foreign_item.id);
 938             return;
 939         }
 940
 941         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 942         visit::walk_foreign_item(self, foreign_item);
 943     }
 944
 945     fn visit_block(&mut self, block: &'a Block) {
 946         let orig_current_module = self.resolver.current_module;
 947         let orig_current_legacy_scope = self.current_legacy_scope;
 948         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 949         visit::walk_block(self, block);
 950         self.resolver.current_module = orig_current_module;
 951         self.current_legacy_scope = orig_current_legacy_scope;
 952     }
 953
 954     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 955         let parent = self.resolver.current_module;
 956
 957         if let TraitItemKind::Macro(_) = item.node {
 958             self.visit_invoc(item.id);
 959             return
 960         }
 961
 962         // Add the item to the trait info.
 963         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 964         let (def, ns) = match item.node {
 965             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 966             TraitItemKind::Method(ref sig, _) => {
 967                 if sig.decl.has_self() {
 968                     self.resolver.has_self.insert(item_def_id);
 969                 }
 970                 (Def::Method(item_def_id), ValueNS)
 971             }
 972             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
 973             TraitItemKind::Macro(_) => bug!(),  // handled above
 974         };
 975
 976         let vis = ty::Visibility::Public;
 977         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
 978
 979         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
 980         visit::walk_trait_item(self, item);
 981         self.resolver.current_module = parent;
 982     }
 983
 984     fn visit_token(&mut self, t: Token) {
 985         if let Token::Interpolated(nt) = t {
 986             if let token::NtExpr(ref expr) = nt.0 {
 987                 if let ast::ExprKind::Mac(..) = expr.node {
 988                     self.visit_invoc(expr.id);
 989                 }
 990             }
 991         }
 992     }
 993
 994     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
 995         if !attr.is_sugared_doc && is_builtin_attr(attr) {
 996             let parent_scope = ParentScope {
 997                 module: self.resolver.current_module.nearest_item_scope(),
 998                 expansion: self.expansion,
 999                 legacy: self.current_legacy_scope,
1000                 // Let's hope discerning built-in attributes from derive helpers is not necessary
1001                 derives: Vec::new(),
1002             };
1003             parent_scope.module.builtin_attrs.borrow_mut().push((
1004                 attr.path.segments[0].ident, parent_scope
1005             ));
1006         }
1007         visit::walk_attribute(self, attr);
1008     }
1009 }