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, emit_feature_err, GateIssue};
  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> Resolver<'a> {
  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::PathRoot.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::PathRoot.name()
 157         };
 158         match use_tree.kind {
 159             ast::UseTreeKind::Simple(rename, ..) => {
 160                 let mut ident = use_tree.ident().gensym_if_underscore();
 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::SelfLower.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::SelfLower.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::PathRoot.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                     source: source.ident,
 234                     target: ident,
 235                     source_bindings: PerNS {
 236                         type_ns: Cell::new(Err(Undetermined)),
 237                         value_ns: Cell::new(Err(Undetermined)),
 238                         macro_ns: Cell::new(Err(Undetermined)),
 239                     },
 240                     target_bindings: PerNS {
 241                         type_ns: Cell::new(None),
 242                         value_ns: Cell::new(None),
 243                         macro_ns: Cell::new(None),
 244                     },
 245                     type_ns_only,
 246                 };
 247                 self.add_import_directive(
 248                     module_path,
 249                     subclass,
 250                     use_tree.span,
 251                     id,
 252                     root_span,
 253                     item.id,
 254                     vis,
 255                     parent_scope,
 256                 );
 257             }
 258             ast::UseTreeKind::Glob => {
 259                 let subclass = GlobImport {
 260                     is_prelude: attr::contains_name(&item.attrs, "prelude_import"),
 261                     max_vis: Cell::new(ty::Visibility::Invisible),
 262                 };
 263                 self.add_import_directive(
 264                     prefix,
 265                     subclass,
 266                     use_tree.span,
 267                     id,
 268                     root_span,
 269                     item.id,
 270                     vis,
 271                     parent_scope,
 272                 );
 273             }
 274             ast::UseTreeKind::Nested(ref items) => {
 275                 // Ensure there is at most one `self` in the list
 276                 let self_spans = items.iter().filter_map(|&(ref use_tree, _)| {
 277                     if let ast::UseTreeKind::Simple(..) = use_tree.kind {
 278                         if use_tree.ident().name == keywords::SelfLower.name() {
 279                             return Some(use_tree.span);
 280                         }
 281                     }
 282
 283                     None
 284                 }).collect::<Vec<_>>();
 285                 if self_spans.len() > 1 {
 286                     let mut e = resolve_struct_error(self,
 287                         self_spans[0],
 288                         ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 289
 290                     for other_span in self_spans.iter().skip(1) {
 291                         e.span_label(*other_span, "another `self` import appears here");
 292                     }
 293
 294                     e.emit();
 295                 }
 296
 297                 for &(ref tree, id) in items {
 298                     self.build_reduced_graph_for_use_tree(
 299                         // This particular use tree
 300                         tree, id, &prefix, true,
 301                         // The whole `use` item
 302                         parent_scope.clone(), item, vis, root_span,
 303                     );
 304                 }
 305
 306                 // Empty groups `a::b::{}` are turned into synthetic `self` imports
 307                 // `a::b::c::{self as _}`, so that their prefixes are correctly
 308                 // resolved and checked for privacy/stability/etc.
 309                 if items.is_empty() && !empty_for_self(&prefix) {
 310                     let new_span = prefix[prefix.len() - 1].ident.span;
 311                     let tree = ast::UseTree {
 312                         prefix: ast::Path::from_ident(
 313                             Ident::new(keywords::SelfLower.name(), new_span)
 314                         ),
 315                         kind: ast::UseTreeKind::Simple(
 316                             Some(Ident::new(keywords::Underscore.name().gensymed(), new_span)),
 317                             ast::DUMMY_NODE_ID,
 318                             ast::DUMMY_NODE_ID,
 319                         ),
 320                         span: use_tree.span,
 321                     };
 322                     self.build_reduced_graph_for_use_tree(
 323                         // This particular use tree
 324                         &tree, id, &prefix, true,
 325                         // The whole `use` item
 326                         parent_scope, item, ty::Visibility::Invisible, root_span,
 327                     );
 328                 }
 329             }
 330         }
 331     }
 332
 333     /// Constructs the reduced graph for one item.
 334     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_scope: ParentScope<'a>) {
 335         let parent = parent_scope.module;
 336         let expansion = parent_scope.expansion;
 337         let ident = item.ident.gensym_if_underscore();
 338         let sp = item.span;
 339         let vis = self.resolve_visibility(&item.vis);
 340
 341         match item.node {
 342             ItemKind::Use(ref use_tree) => {
 343                 self.build_reduced_graph_for_use_tree(
 344                     // This particular use tree
 345                     use_tree, item.id, &[], false,
 346                     // The whole `use` item
 347                     parent_scope, item, vis, use_tree.span,
 348                 );
 349             }
 350
 351             ItemKind::ExternCrate(orig_name) => {
 352                 let module = if orig_name.is_none() && ident.name == keywords::SelfLower.name() {
 353                     self.session
 354                         .struct_span_err(item.span, "`extern crate self;` requires renaming")
 355                         .span_suggestion(item.span, "try", "extern crate self as name;".into())
 356                         .emit();
 357                     return;
 358                 } else if orig_name == Some(keywords::SelfLower.name()) {
 359                     if !self.session.features_untracked().extern_crate_self {
 360                         emit_feature_err(&self.session.parse_sess, "extern_crate_self", item.span,
 361                                          GateIssue::Language, "`extern crate self` is unstable");
 362                     }
 363                     self.graph_root
 364                 } else {
 365                     let crate_id = self.crate_loader.process_extern_crate(item, &self.definitions);
 366                     self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
 367                 };
 368
 369                 self.populate_module_if_necessary(module);
 370                 if injected_crate_name().map_or(false, |name| ident.name == name) {
 371                     self.injected_crate = Some(module);
 372                 }
 373
 374                 let used = self.process_legacy_macro_imports(item, module, &parent_scope);
 375                 let binding =
 376                     (module, ty::Visibility::Public, sp, expansion).to_name_binding(self.arenas);
 377                 let directive = self.arenas.alloc_import_directive(ImportDirective {
 378                     root_id: item.id,
 379                     id: item.id,
 380                     parent_scope,
 381                     imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 382                     subclass: ImportDirectiveSubclass::ExternCrate {
 383                         source: orig_name,
 384                         target: ident,
 385                     },
 386                     root_span: item.span,
 387                     span: item.span,
 388                     module_path: Vec::new(),
 389                     vis: Cell::new(vis),
 390                     used: Cell::new(used),
 391                 });
 392                 self.potentially_unused_imports.push(directive);
 393                 let imported_binding = self.import(binding, directive);
 394                 if ptr::eq(self.current_module, self.graph_root) {
 395                     if let Some(entry) = self.extern_prelude.get(&ident.modern()) {
 396                         if expansion != Mark::root() && orig_name.is_some() &&
 397                            entry.extern_crate_item.is_none() {
 398                             self.session.span_err(item.span, "macro-expanded `extern crate` items \
 399                                                               cannot shadow names passed with \
 400                                                               `--extern`");
 401                         }
 402                     }
 403                     let entry = self.extern_prelude.entry(ident.modern())
 404                                                    .or_insert(ExternPreludeEntry {
 405                         extern_crate_item: None,
 406                         introduced_by_item: true,
 407                     });
 408                     entry.extern_crate_item = Some(imported_binding);
 409                     if orig_name.is_some() {
 410                         entry.introduced_by_item = true;
 411                     }
 412                 }
 413                 self.define(parent, ident, TypeNS, imported_binding);
 414             }
 415
 416             ItemKind::GlobalAsm(..) => {}
 417
 418             ItemKind::Mod(..) if ident == keywords::Invalid.ident() => {} // Crate root
 419
 420             ItemKind::Mod(..) => {
 421                 let def_id = self.definitions.local_def_id(item.id);
 422                 let module_kind = ModuleKind::Def(Def::Mod(def_id), ident.name);
 423                 let module = self.arenas.alloc_module(ModuleData {
 424                     no_implicit_prelude: parent.no_implicit_prelude || {
 425                         attr::contains_name(&item.attrs, "no_implicit_prelude")
 426                     },
 427                     ..ModuleData::new(Some(parent), module_kind, def_id, expansion, item.span)
 428                 });
 429                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 430                 self.module_map.insert(def_id, module);
 431
 432                 // Descend into the module.
 433                 self.current_module = module;
 434             }
 435
 436             // Handled in `rustc_metadata::{native_libs,link_args}`
 437             ItemKind::ForeignMod(..) => {}
 438
 439             // These items live in the value namespace.
 440             ItemKind::Static(_, m, _) => {
 441                 let mutbl = m == Mutability::Mutable;
 442                 let def = Def::Static(self.definitions.local_def_id(item.id), mutbl);
 443                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 444             }
 445             ItemKind::Const(..) => {
 446                 let def = Def::Const(self.definitions.local_def_id(item.id));
 447                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 448             }
 449             ItemKind::Fn(..) => {
 450                 let def = Def::Fn(self.definitions.local_def_id(item.id));
 451                 self.define(parent, ident, ValueNS, (def, vis, sp, expansion));
 452
 453                 // Functions introducing procedural macros reserve a slot
 454                 // in the macro namespace as well (see #52225).
 455                 if attr::contains_name(&item.attrs, "proc_macro") ||
 456                    attr::contains_name(&item.attrs, "proc_macro_attribute") {
 457                     let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 458                     self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 459                 }
 460                 if let Some(attr) = attr::find_by_name(&item.attrs, "proc_macro_derive") {
 461                     if let Some(trait_attr) =
 462                             attr.meta_item_list().and_then(|list| list.get(0).cloned()) {
 463                         if let Some(ident) = trait_attr.name().map(Ident::with_empty_ctxt) {
 464                             let sp = trait_attr.span;
 465                             let def = Def::Macro(def.def_id(), MacroKind::ProcMacroStub);
 466                             self.define(parent, ident, MacroNS, (def, vis, sp, expansion));
 467                         }
 468                     }
 469                 }
 470             }
 471
 472             // These items live in the type namespace.
 473             ItemKind::Ty(..) => {
 474                 let def = Def::TyAlias(self.definitions.local_def_id(item.id));
 475                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 476             }
 477
 478             ItemKind::Existential(_, _) => {
 479                 let def = Def::Existential(self.definitions.local_def_id(item.id));
 480                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 481             }
 482
 483             ItemKind::Enum(ref enum_definition, _) => {
 484                 let def = Def::Enum(self.definitions.local_def_id(item.id));
 485                 let module_kind = ModuleKind::Def(def, ident.name);
 486                 let module = self.new_module(parent,
 487                                              module_kind,
 488                                              parent.normal_ancestor_id,
 489                                              expansion,
 490                                              item.span);
 491                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 492
 493                 for variant in &(*enum_definition).variants {
 494                     self.build_reduced_graph_for_variant(variant, module, vis, expansion);
 495                 }
 496             }
 497
 498             ItemKind::TraitAlias(..) => {
 499                 let def = Def::TraitAlias(self.definitions.local_def_id(item.id));
 500                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 501             }
 502
 503             // These items live in both the type and value namespaces.
 504             ItemKind::Struct(ref struct_def, _) => {
 505                 // Define a name in the type namespace.
 506                 let def_id = self.definitions.local_def_id(item.id);
 507                 let def = Def::Struct(def_id);
 508                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 509
 510                 let mut ctor_vis = vis;
 511
 512                 let has_non_exhaustive = attr::contains_name(&item.attrs, "non_exhaustive");
 513
 514                 // If the structure is marked as non_exhaustive then lower the visibility
 515                 // to within the crate.
 516                 if has_non_exhaustive && vis == ty::Visibility::Public {
 517                     ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 518                 }
 519
 520                 // Record field names for error reporting.
 521                 let field_names = struct_def.fields().iter().filter_map(|field| {
 522                     let field_vis = self.resolve_visibility(&field.vis);
 523                     if ctor_vis.is_at_least(field_vis, &*self) {
 524                         ctor_vis = field_vis;
 525                     }
 526                     field.ident.map(|ident| ident.name)
 527                 }).collect();
 528                 let item_def_id = self.definitions.local_def_id(item.id);
 529                 self.insert_field_names(item_def_id, field_names);
 530
 531                 // If this is a tuple or unit struct, define a name
 532                 // in the value namespace as well.
 533                 if !struct_def.is_struct() {
 534                     let ctor_def = Def::StructCtor(self.definitions.local_def_id(struct_def.id()),
 535                                                    CtorKind::from_ast(struct_def));
 536                     self.define(parent, ident, ValueNS, (ctor_def, ctor_vis, sp, expansion));
 537                     self.struct_constructors.insert(def.def_id(), (ctor_def, ctor_vis));
 538                 }
 539             }
 540
 541             ItemKind::Union(ref vdata, _) => {
 542                 let def = Def::Union(self.definitions.local_def_id(item.id));
 543                 self.define(parent, ident, TypeNS, (def, vis, sp, expansion));
 544
 545                 // Record field names for error reporting.
 546                 let field_names = vdata.fields().iter().filter_map(|field| {
 547                     self.resolve_visibility(&field.vis);
 548                     field.ident.map(|ident| ident.name)
 549                 }).collect();
 550                 let item_def_id = self.definitions.local_def_id(item.id);
 551                 self.insert_field_names(item_def_id, field_names);
 552             }
 553
 554             ItemKind::Impl(..) => {}
 555
 556             ItemKind::Trait(..) => {
 557                 let def_id = self.definitions.local_def_id(item.id);
 558
 559                 // Add all the items within to a new module.
 560                 let module_kind = ModuleKind::Def(Def::Trait(def_id), ident.name);
 561                 let module = self.new_module(parent,
 562                                              module_kind,
 563                                              parent.normal_ancestor_id,
 564                                              expansion,
 565                                              item.span);
 566                 self.define(parent, ident, TypeNS, (module, vis, sp, expansion));
 567                 self.current_module = module;
 568             }
 569
 570             ItemKind::MacroDef(..) | ItemKind::Mac(_) => unreachable!(),
 571         }
 572     }
 573
 574     // Constructs the reduced graph for one variant. Variants exist in the
 575     // type and value namespaces.
 576     fn build_reduced_graph_for_variant(&mut self,
 577                                        variant: &Variant,
 578                                        parent: Module<'a>,
 579                                        vis: ty::Visibility,
 580                                        expansion: Mark) {
 581         let ident = variant.node.ident;
 582         let def_id = self.definitions.local_def_id(variant.node.data.id());
 583
 584         // Define a name in the type namespace.
 585         let def = Def::Variant(def_id);
 586         self.define(parent, ident, TypeNS, (def, vis, variant.span, expansion));
 587
 588         // Define a constructor name in the value namespace.
 589         // Braced variants, unlike structs, generate unusable names in
 590         // value namespace, they are reserved for possible future use.
 591         let ctor_kind = CtorKind::from_ast(&variant.node.data);
 592         let ctor_def = Def::VariantCtor(def_id, ctor_kind);
 593
 594         self.define(parent, ident, ValueNS, (ctor_def, vis, variant.span, expansion));
 595     }
 596
 597     /// Constructs the reduced graph for one foreign item.
 598     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem, expansion: Mark) {
 599         let (def, ns) = match item.node {
 600             ForeignItemKind::Fn(..) => {
 601                 (Def::Fn(self.definitions.local_def_id(item.id)), ValueNS)
 602             }
 603             ForeignItemKind::Static(_, m) => {
 604                 (Def::Static(self.definitions.local_def_id(item.id), m), ValueNS)
 605             }
 606             ForeignItemKind::Ty => {
 607                 (Def::ForeignTy(self.definitions.local_def_id(item.id)), TypeNS)
 608             }
 609             ForeignItemKind::Macro(_) => unreachable!(),
 610         };
 611         let parent = self.current_module;
 612         let vis = self.resolve_visibility(&item.vis);
 613         self.define(parent, item.ident, ns, (def, vis, item.span, expansion));
 614     }
 615
 616     fn build_reduced_graph_for_block(&mut self, block: &Block, expansion: Mark) {
 617         let parent = self.current_module;
 618         if self.block_needs_anonymous_module(block) {
 619             let module = self.new_module(parent,
 620                                          ModuleKind::Block(block.id),
 621                                          parent.normal_ancestor_id,
 622                                          expansion,
 623                                          block.span);
 624             self.block_map.insert(block.id, module);
 625             self.current_module = module; // Descend into the block.
 626         }
 627     }
 628
 629     /// Builds the reduced graph for a single item in an external crate.
 630     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'a>, child: Export) {
 631         let Export { ident, def, vis, span } = child;
 632         // FIXME: We shouldn't create the gensym here, it should come from metadata,
 633         // but metadata cannot encode gensyms currently, so we create it here.
 634         // This is only a guess, two equivalent idents may incorrectly get different gensyms here.
 635         let ident = ident.gensym_if_underscore();
 636         let def_id = def.def_id();
 637         let expansion = Mark::root(); // FIXME(jseyfried) intercrate hygiene
 638         match def {
 639             Def::Mod(..) | Def::Enum(..) => {
 640                 let module = self.new_module(parent,
 641                                              ModuleKind::Def(def, ident.name),
 642                                              def_id,
 643                                              expansion,
 644                                              span);
 645                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 646             }
 647             Def::Variant(..) | Def::TyAlias(..) | Def::ForeignTy(..) => {
 648                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 649             }
 650             Def::Fn(..) | Def::Static(..) | Def::Const(..) | Def::VariantCtor(..) => {
 651                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 652             }
 653             Def::StructCtor(..) => {
 654                 self.define(parent, ident, ValueNS, (def, vis, DUMMY_SP, expansion));
 655
 656                 if let Some(struct_def_id) =
 657                         self.cstore.def_key(def_id).parent
 658                             .map(|index| DefId { krate: def_id.krate, index: index }) {
 659                     self.struct_constructors.insert(struct_def_id, (def, vis));
 660                 }
 661             }
 662             Def::Trait(..) => {
 663                 let module_kind = ModuleKind::Def(def, ident.name);
 664                 let module = self.new_module(parent,
 665                                              module_kind,
 666                                              parent.normal_ancestor_id,
 667                                              expansion,
 668                                              span);
 669                 self.define(parent, ident, TypeNS, (module, vis, DUMMY_SP, expansion));
 670
 671                 for child in self.cstore.item_children_untracked(def_id, self.session) {
 672                     let ns = if let Def::AssociatedTy(..) = child.def { TypeNS } else { ValueNS };
 673                     self.define(module, child.ident, ns,
 674                                 (child.def, ty::Visibility::Public, DUMMY_SP, expansion));
 675
 676                     if self.cstore.associated_item_cloned_untracked(child.def.def_id())
 677                            .method_has_self_argument {
 678                         self.has_self.insert(child.def.def_id());
 679                     }
 680                 }
 681                 module.populated.set(true);
 682             }
 683             Def::Struct(..) | Def::Union(..) => {
 684                 self.define(parent, ident, TypeNS, (def, vis, DUMMY_SP, expansion));
 685
 686                 // Record field names for error reporting.
 687                 let field_names = self.cstore.struct_field_names_untracked(def_id);
 688                 self.insert_field_names(def_id, field_names);
 689             }
 690             Def::Macro(..) => {
 691                 self.define(parent, ident, MacroNS, (def, vis, DUMMY_SP, expansion));
 692             }
 693             _ => bug!("unexpected definition: {:?}", def)
 694         }
 695     }
 696
 697     pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
 698         if def_id.krate == LOCAL_CRATE {
 699             return self.module_map[&def_id]
 700         }
 701
 702         let macros_only = self.cstore.dep_kind_untracked(def_id.krate).macros_only();
 703         if let Some(&module) = self.extern_module_map.get(&(def_id, macros_only)) {
 704             return module;
 705         }
 706
 707         let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
 708             (self.cstore.crate_name_untracked(def_id.krate).as_interned_str(), None)
 709         } else {
 710             let def_key = self.cstore.def_key(def_id);
 711             (def_key.disambiguated_data.data.get_opt_name().unwrap(),
 712              Some(self.get_module(DefId { index: def_key.parent.unwrap(), ..def_id })))
 713         };
 714
 715         let kind = ModuleKind::Def(Def::Mod(def_id), name.as_symbol());
 716         let module =
 717             self.arenas.alloc_module(ModuleData::new(parent, kind, def_id, Mark::root(), DUMMY_SP));
 718         self.extern_module_map.insert((def_id, macros_only), module);
 719         module
 720     }
 721
 722     pub fn macro_def_scope(&mut self, expansion: Mark) -> Module<'a> {
 723         let def_id = self.macro_defs[&expansion];
 724         if let Some(id) = self.definitions.as_local_node_id(def_id) {
 725             self.local_macro_def_scopes[&id]
 726         } else if def_id.krate == CrateNum::BuiltinMacros {
 727             self.injected_crate.unwrap_or(self.graph_root)
 728         } else {
 729             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();
 730             self.get_module(module_def_id)
 731         }
 732     }
 733
 734     pub fn get_macro(&mut self, def: Def) -> Lrc<SyntaxExtension> {
 735         let def_id = match def {
 736             Def::Macro(def_id, ..) => def_id,
 737             Def::NonMacroAttr(attr_kind) => return Lrc::new(SyntaxExtension::NonMacroAttr {
 738                 mark_used: attr_kind == NonMacroAttrKind::Tool,
 739             }),
 740             _ => panic!("expected `Def::Macro` or `Def::NonMacroAttr`"),
 741         };
 742         if let Some(ext) = self.macro_map.get(&def_id) {
 743             return ext.clone();
 744         }
 745
 746         let macro_def = match self.cstore.load_macro_untracked(def_id, &self.session) {
 747             LoadedMacro::MacroDef(macro_def) => macro_def,
 748             LoadedMacro::ProcMacro(ext) => return ext,
 749         };
 750
 751         let ext = Lrc::new(macro_rules::compile(&self.session.parse_sess,
 752                                                &self.session.features_untracked(),
 753                                                &macro_def,
 754                                                self.cstore.crate_edition_untracked(def_id.krate)));
 755         self.macro_map.insert(def_id, ext.clone());
 756         ext
 757     }
 758
 759     /// Ensures that the reduced graph rooted at the given external module
 760     /// is built, building it if it is not.
 761     pub fn populate_module_if_necessary(&mut self, module: Module<'a>) {
 762         if module.populated.get() { return }
 763         let def_id = module.def_id().unwrap();
 764         for child in self.cstore.item_children_untracked(def_id, self.session) {
 765             self.build_reduced_graph_for_external_crate_def(module, child);
 766         }
 767         module.populated.set(true)
 768     }
 769
 770     fn legacy_import_macro(&mut self,
 771                            name: Name,
 772                            binding: &'a NameBinding<'a>,
 773                            span: Span,
 774                            allow_shadowing: bool) {
 775         if self.macro_use_prelude.insert(name, binding).is_some() && !allow_shadowing {
 776             let msg = format!("`{}` is already in scope", name);
 777             let note =
 778                 "macro-expanded `#[macro_use]`s may not shadow existing macros (see RFC 1560)";
 779             self.session.struct_span_err(span, &msg).note(note).emit();
 780         }
 781     }
 782
 783     // This returns true if we should consider the underlying `extern crate` to be used.
 784     fn process_legacy_macro_imports(&mut self, item: &Item, module: Module<'a>,
 785                                     parent_scope: &ParentScope<'a>) -> bool {
 786         let mut import_all = None;
 787         let mut single_imports = Vec::new();
 788         for attr in &item.attrs {
 789             if attr.check_name("macro_use") {
 790                 if self.current_module.parent.is_some() {
 791                     span_err!(self.session, item.span, E0468,
 792                         "an `extern crate` loading macros must be at the crate root");
 793                 }
 794                 if let ItemKind::ExternCrate(Some(orig_name)) = item.node {
 795                     if orig_name == keywords::SelfLower.name() {
 796                         self.session.span_err(attr.span,
 797                             "`macro_use` is not supported on `extern crate self`");
 798                     }
 799                 }
 800                 let ill_formed = |span| span_err!(self.session, span, E0466, "bad macro import");
 801                 match attr.meta() {
 802                     Some(meta) => match meta.node {
 803                         MetaItemKind::Word => {
 804                             import_all = Some(meta.span);
 805                             break;
 806                         }
 807                         MetaItemKind::List(nested_metas) => for nested_meta in nested_metas {
 808                             match nested_meta.word() {
 809                                 Some(word) => single_imports.push((word.name(), word.span)),
 810                                 None => ill_formed(nested_meta.span),
 811                             }
 812                         }
 813                         MetaItemKind::NameValue(..) => ill_formed(meta.span),
 814                     }
 815                     None => ill_formed(attr.span()),
 816                 }
 817             }
 818         }
 819
 820         let arenas = self.arenas;
 821         let macro_use_directive = |span| arenas.alloc_import_directive(ImportDirective {
 822             root_id: item.id,
 823             id: item.id,
 824             parent_scope: parent_scope.clone(),
 825             imported_module: Cell::new(Some(ModuleOrUniformRoot::Module(module))),
 826             subclass: ImportDirectiveSubclass::MacroUse,
 827             root_span: span,
 828             span,
 829             module_path: Vec::new(),
 830             vis: Cell::new(ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX))),
 831             used: Cell::new(false),
 832         });
 833
 834         let allow_shadowing = parent_scope.expansion == Mark::root();
 835         if let Some(span) = import_all {
 836             let directive = macro_use_directive(span);
 837             self.potentially_unused_imports.push(directive);
 838             module.for_each_child(|ident, ns, binding| if ns == MacroNS {
 839                 let imported_binding = self.import(binding, directive);
 840                 self.legacy_import_macro(ident.name, imported_binding, span, allow_shadowing);
 841             });
 842         } else {
 843             for (name, span) in single_imports.iter().cloned() {
 844                 let ident = Ident::with_empty_ctxt(name);
 845                 let result = self.resolve_ident_in_module(
 846                     ModuleOrUniformRoot::Module(module),
 847                     ident,
 848                     MacroNS,
 849                     None,
 850                     false,
 851                     span,
 852                 );
 853                 if let Ok(binding) = result {
 854                     let directive = macro_use_directive(span);
 855                     self.potentially_unused_imports.push(directive);
 856                     let imported_binding = self.import(binding, directive);
 857                     self.legacy_import_macro(name, imported_binding, span, allow_shadowing);
 858                 } else {
 859                     span_err!(self.session, span, E0469, "imported macro not found");
 860                 }
 861             }
 862         }
 863         import_all.is_some() || !single_imports.is_empty()
 864     }
 865
 866     // does this attribute list contain "macro_use"?
 867     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 868         for attr in attrs {
 869             if attr.check_name("macro_escape") {
 870                 let msg = "macro_escape is a deprecated synonym for macro_use";
 871                 let mut err = self.session.struct_span_warn(attr.span, msg);
 872                 if let ast::AttrStyle::Inner = attr.style {
 873                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 874                 } else {
 875                     err.emit();
 876                 }
 877             } else if !attr.check_name("macro_use") {
 878                 continue;
 879             }
 880
 881             if !attr.is_word() {
 882                 self.session.span_err(attr.span, "arguments to macro_use are not allowed here");
 883             }
 884             return true;
 885         }
 886
 887         false
 888     }
 889 }
 890
 891 pub struct BuildReducedGraphVisitor<'a, 'b: 'a> {
 892     pub resolver: &'a mut Resolver<'b>,
 893     pub current_legacy_scope: LegacyScope<'b>,
 894     pub expansion: Mark,
 895 }
 896
 897 impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
 898     fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
 899         let mark = id.placeholder_to_mark();
 900         self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
 901         let invocation = self.resolver.invocations[&mark];
 902         invocation.module.set(self.resolver.current_module);
 903         invocation.parent_legacy_scope.set(self.current_legacy_scope);
 904         invocation
 905     }
 906 }
 907
 908 macro_rules! method {
 909     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 910         fn $visit(&mut self, node: &'a $ty) {
 911             if let $invoc(..) = node.node {
 912                 self.visit_invoc(node.id);
 913             } else {
 914                 visit::$walk(self, node);
 915             }
 916         }
 917     }
 918 }
 919
 920 impl<'a, 'b> Visitor<'a> for BuildReducedGraphVisitor<'a, 'b> {
 921     method!(visit_impl_item: ast::ImplItem, ast::ImplItemKind::Macro, walk_impl_item);
 922     method!(visit_expr:      ast::Expr,     ast::ExprKind::Mac,       walk_expr);
 923     method!(visit_pat:       ast::Pat,      ast::PatKind::Mac,        walk_pat);
 924     method!(visit_ty:        ast::Ty,       ast::TyKind::Mac,         walk_ty);
 925
 926     fn visit_item(&mut self, item: &'a Item) {
 927         let macro_use = match item.node {
 928             ItemKind::MacroDef(..) => {
 929                 self.resolver.define_macro(item, self.expansion, &mut self.current_legacy_scope);
 930                 return
 931             }
 932             ItemKind::Mac(..) => {
 933                 self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(item.id));
 934                 return
 935             }
 936             ItemKind::Mod(..) => self.resolver.contains_macro_use(&item.attrs),
 937             _ => false,
 938         };
 939
 940         let orig_current_module = self.resolver.current_module;
 941         let orig_current_legacy_scope = self.current_legacy_scope;
 942         let parent_scope = ParentScope {
 943             module: self.resolver.current_module,
 944             expansion: self.expansion,
 945             legacy: self.current_legacy_scope,
 946             derives: Vec::new(),
 947         };
 948         self.resolver.build_reduced_graph_for_item(item, parent_scope);
 949         visit::walk_item(self, item);
 950         self.resolver.current_module = orig_current_module;
 951         if !macro_use {
 952             self.current_legacy_scope = orig_current_legacy_scope;
 953         }
 954     }
 955
 956     fn visit_stmt(&mut self, stmt: &'a ast::Stmt) {
 957         if let ast::StmtKind::Mac(..) = stmt.node {
 958             self.current_legacy_scope = LegacyScope::Invocation(self.visit_invoc(stmt.id));
 959         } else {
 960             visit::walk_stmt(self, stmt);
 961         }
 962     }
 963
 964     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 965         if let ForeignItemKind::Macro(_) = foreign_item.node {
 966             self.visit_invoc(foreign_item.id);
 967             return;
 968         }
 969
 970         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, self.expansion);
 971         visit::walk_foreign_item(self, foreign_item);
 972     }
 973
 974     fn visit_block(&mut self, block: &'a Block) {
 975         let orig_current_module = self.resolver.current_module;
 976         let orig_current_legacy_scope = self.current_legacy_scope;
 977         self.resolver.build_reduced_graph_for_block(block, self.expansion);
 978         visit::walk_block(self, block);
 979         self.resolver.current_module = orig_current_module;
 980         self.current_legacy_scope = orig_current_legacy_scope;
 981     }
 982
 983     fn visit_trait_item(&mut self, item: &'a TraitItem) {
 984         let parent = self.resolver.current_module;
 985
 986         if let TraitItemKind::Macro(_) = item.node {
 987             self.visit_invoc(item.id);
 988             return
 989         }
 990
 991         // Add the item to the trait info.
 992         let item_def_id = self.resolver.definitions.local_def_id(item.id);
 993         let (def, ns) = match item.node {
 994             TraitItemKind::Const(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 995             TraitItemKind::Method(ref sig, _) => {
 996                 if sig.decl.has_self() {
 997                     self.resolver.has_self.insert(item_def_id);
 998                 }
 999                 (Def::Method(item_def_id), ValueNS)
1000             }
1001             TraitItemKind::Type(..) => (Def::AssociatedTy(item_def_id), TypeNS),
1002             TraitItemKind::Macro(_) => bug!(),  // handled above
1003         };
1004
1005         let vis = ty::Visibility::Public;
1006         self.resolver.define(parent, item.ident, ns, (def, vis, item.span, self.expansion));
1007
1008         self.resolver.current_module = parent.parent.unwrap(); // nearest normal ancestor
1009         visit::walk_trait_item(self, item);
1010         self.resolver.current_module = parent;
1011     }
1012
1013     fn visit_token(&mut self, t: Token) {
1014         if let Token::Interpolated(nt) = t {
1015             if let token::NtExpr(ref expr) = nt.0 {
1016                 if let ast::ExprKind::Mac(..) = expr.node {
1017                     self.visit_invoc(expr.id);
1018                 }
1019             }
1020         }
1021     }
1022
1023     fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
1024         if !attr.is_sugared_doc && is_builtin_attr(attr) {
1025             let parent_scope = ParentScope {
1026                 module: self.resolver.current_module.nearest_item_scope(),
1027                 expansion: self.expansion,
1028                 legacy: self.current_legacy_scope,
1029                 // Let's hope discerning built-in attributes from derive helpers is not necessary
1030                 derives: Vec::new(),
1031             };
1032             parent_scope.module.builtin_attrs.borrow_mut().push((
1033                 attr.path.segments[0].ident, parent_scope
1034             ));
1035         }
1036         visit::walk_attribute(self, attr);
1037     }
1038
1039     fn visit_ident(&mut self, ident: Ident) {
1040         if ident.name == keywords::DollarCrate.name() {
1041             let name = match self.resolver.resolve_crate_root(ident).kind {
1042                 ModuleKind::Def(_, name) if name != keywords::Invalid.name() => name,
1043                 _ => keywords::Crate.name(),
1044             };
1045             ident.span.ctxt().set_dollar_crate_name(name);
1046         }
1047         visit::walk_ident(self, ident);
1048     }
1049 }