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 resolve_imports::ImportDirectiveSubclass::{self, GlobImport};
  17 use Module;
  18 use Namespace::{self, TypeNS, ValueNS};
  19 use {NameBinding, NameBindingKind};
  20 use ParentLink::{ModuleParentLink, BlockParentLink};
  21 use Resolver;
  22 use {resolve_error, resolve_struct_error, ResolutionError};
  23
  24 use rustc::middle::cstore::{CrateStore, ChildItem, DlDef};
  25 use rustc::lint;
  26 use rustc::hir::def::*;
  27 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
  28 use rustc::ty::{self, VariantKind};
  29
  30 use syntax::ast::{Name, NodeId};
  31 use syntax::attr::AttrMetaMethods;
  32 use syntax::parse::token::keywords;
  33 use syntax::codemap::{Span, DUMMY_SP};
  34
  35 use rustc::hir;
  36 use rustc::hir::{Block, DeclItem};
  37 use rustc::hir::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  38 use rustc::hir::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  39 use rustc::hir::{ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  40 use rustc::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  41 use rustc::hir::{PathListIdent, PathListMod, StmtDecl};
  42 use rustc::hir::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  43 use rustc::hir::intravisit::{self, Visitor};
  44
  45 trait ToNameBinding<'a> {
  46     fn to_name_binding(self) -> NameBinding<'a>;
  47 }
  48
  49 impl<'a> ToNameBinding<'a> for (Module<'a>, Span) {
  50     fn to_name_binding(self) -> NameBinding<'a> {
  51         NameBinding::create_from_module(self.0, Some(self.1))
  52     }
  53 }
  54
  55 impl<'a> ToNameBinding<'a> for (Def, Span, ty::Visibility) {
  56     fn to_name_binding(self) -> NameBinding<'a> {
  57         NameBinding { kind: NameBindingKind::Def(self.0), span: Some(self.1), vis: self.2 }
  58     }
  59 }
  60
  61 impl<'b, 'tcx:'b> Resolver<'b, 'tcx> {
  62     /// Constructs the reduced graph for the entire crate.
  63     pub fn build_reduced_graph(&mut self, krate: &hir::Crate) {
  64         let mut visitor = BuildReducedGraphVisitor {
  65             parent: self.graph_root,
  66             resolver: self,
  67         };
  68         intravisit::walk_crate(&mut visitor, krate);
  69     }
  70
  71     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined.
  72     fn try_define<T>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T)
  73         where T: ToNameBinding<'b>
  74     {
  75         let _ = parent.try_define_child(name, ns, def.to_name_binding());
  76     }
  77
  78     /// Defines `name` in namespace `ns` of module `parent` to be `def` if it is not yet defined;
  79     /// otherwise, reports an error.
  80     fn define<T: ToNameBinding<'b>>(&self, parent: Module<'b>, name: Name, ns: Namespace, def: T) {
  81         let binding = def.to_name_binding();
  82         if let Err(old_binding) = parent.try_define_child(name, ns, binding.clone()) {
  83             self.report_conflict(parent, name, ns, old_binding, &binding);
  84         }
  85     }
  86
  87     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
  88         fn is_item(statement: &hir::Stmt) -> bool {
  89             if let StmtDecl(ref declaration, _) = statement.node {
  90                 if let DeclItem(_) = declaration.node {
  91                     return true;
  92                 }
  93             }
  94             false
  95         }
  96
  97         // If any statements are items, we need to create an anonymous module
  98         block.stmts.iter().any(is_item)
  99     }
 100
 101     fn sanity_check_import(&self, view_path: &hir::ViewPath, id: NodeId) {
 102         let path = match view_path.node {
 103             ViewPathSimple(_, ref path) |
 104             ViewPathGlob (ref path) |
 105             ViewPathList(ref path, _) => path
 106         };
 107
 108         // Check for type parameters
 109         let found_param = path.segments.iter().any(|segment| {
 110             !segment.parameters.types().is_empty() ||
 111             !segment.parameters.lifetimes().is_empty() ||
 112             !segment.parameters.bindings().is_empty()
 113         });
 114         if found_param {
 115             self.session.span_err(path.span,
 116                                   "type or lifetime parameter is found in import path");
 117         }
 118
 119         // Checking for special identifiers in path
 120         // prevent `self` or `super` at beginning of global path
 121         if path.global && path.segments.len() > 0 {
 122             let first = path.segments[0].identifier.name;
 123             if first == keywords::Super.to_name() || first == keywords::SelfValue.to_name() {
 124                 self.session.add_lint(
 125                     lint::builtin::SUPER_OR_SELF_IN_GLOBAL_PATH, id, path.span,
 126                     format!("expected identifier, found keyword `{}`", first)
 127                 );
 128             }
 129         }
 130     }
 131
 132     /// Constructs the reduced graph for one item.
 133     fn build_reduced_graph_for_item(&mut self, item: &Item, parent_ref: &mut Module<'b>) {
 134         let parent = *parent_ref;
 135         let name = item.name;
 136         let sp = item.span;
 137         self.current_module = parent;
 138         let vis = self.resolve_visibility(&item.vis);
 139
 140         match item.node {
 141             ItemUse(ref view_path) => {
 142                 // Extract and intern the module part of the path. For
 143                 // globs and lists, the path is found directly in the AST;
 144                 // for simple paths we have to munge the path a little.
 145                 let module_path: Vec<Name> = match view_path.node {
 146                     ViewPathSimple(_, ref full_path) => {
 147                         full_path.segments
 148                                  .split_last()
 149                                  .unwrap()
 150                                  .1
 151                                  .iter()
 152                                  .map(|seg| seg.identifier.name)
 153                                  .collect()
 154                     }
 155
 156                     ViewPathGlob(ref module_ident_path) |
 157                     ViewPathList(ref module_ident_path, _) => {
 158                         module_ident_path.segments
 159                                          .iter()
 160                                          .map(|seg| seg.identifier.name)
 161                                          .collect()
 162                     }
 163                 };
 164
 165                 self.sanity_check_import(view_path, item.id);
 166
 167                 // Build up the import directives.
 168                 let is_prelude = item.attrs.iter().any(|attr| attr.name() == "prelude_import");
 169
 170                 match view_path.node {
 171                     ViewPathSimple(binding, ref full_path) => {
 172                         let source_name = full_path.segments.last().unwrap().identifier.name;
 173                         if source_name.as_str() == "mod" || source_name.as_str() == "self" {
 174                             resolve_error(self,
 175                                           view_path.span,
 176                                           ResolutionError::SelfImportsOnlyAllowedWithin);
 177                         }
 178
 179                         let subclass = ImportDirectiveSubclass::single(binding, source_name);
 180                         self.unresolved_imports += 1;
 181                         parent.add_import_directive(module_path,
 182                                                     subclass,
 183                                                     view_path.span,
 184                                                     item.id,
 185                                                     vis,
 186                                                     is_prelude);
 187                     }
 188                     ViewPathList(_, ref source_items) => {
 189                         // Make sure there's at most one `mod` import in the list.
 190                         let mod_spans = source_items.iter()
 191                                                     .filter_map(|item| {
 192                                                         match item.node {
 193                                                             PathListMod { .. } => Some(item.span),
 194                                                             _ => None,
 195                                                         }
 196                                                     })
 197                                                     .collect::<Vec<Span>>();
 198                         if mod_spans.len() > 1 {
 199                             let mut e = resolve_struct_error(self,
 200                                           mod_spans[0],
 201                                           ResolutionError::SelfImportCanOnlyAppearOnceInTheList);
 202                             for other_span in mod_spans.iter().skip(1) {
 203                                 e.span_note(*other_span, "another `self` import appears here");
 204                             }
 205                             e.emit();
 206                         }
 207
 208                         for source_item in source_items {
 209                             let (module_path, name, rename) = match source_item.node {
 210                                 PathListIdent { name, rename, .. } =>
 211                                     (module_path.clone(), name, rename.unwrap_or(name)),
 212                                 PathListMod { rename, .. } => {
 213                                     let name = match module_path.last() {
 214                                         Some(name) => *name,
 215                                         None => {
 216                                             resolve_error(
 217                                                 self,
 218                                                 source_item.span,
 219                                                 ResolutionError::
 220                                                 SelfImportOnlyInImportListWithNonEmptyPrefix
 221                                             );
 222                                             continue;
 223                                         }
 224                                     };
 225                                     let module_path = module_path.split_last().unwrap().1;
 226                                     let rename = rename.unwrap_or(name);
 227                                     (module_path.to_vec(), name, rename)
 228                                 }
 229                             };
 230                             let subclass = ImportDirectiveSubclass::single(rename, name);
 231                             self.unresolved_imports += 1;
 232                             parent.add_import_directive(module_path,
 233                                                         subclass,
 234                                                         source_item.span,
 235                                                         source_item.node.id(),
 236                                                         vis,
 237                                                         is_prelude);
 238                         }
 239                     }
 240                     ViewPathGlob(_) => {
 241                         self.unresolved_imports += 1;
 242                         parent.add_import_directive(module_path,
 243                                                     GlobImport,
 244                                                     view_path.span,
 245                                                     item.id,
 246                                                     vis,
 247                                                     is_prelude);
 248                     }
 249                 }
 250             }
 251
 252             ItemExternCrate(_) => {
 253                 // n.b. we don't need to look at the path option here, because cstore already
 254                 // did
 255                 if let Some(crate_id) = self.session.cstore.extern_mod_stmt_cnum(item.id) {
 256                     let def_id = DefId {
 257                         krate: crate_id,
 258                         index: CRATE_DEF_INDEX,
 259                     };
 260                     let parent_link = ModuleParentLink(parent, name);
 261                     let def = Def::Mod(def_id);
 262                     let module = self.new_extern_crate_module(parent_link, def, vis, item.id);
 263                     self.define(parent, name, TypeNS, (module, sp));
 264
 265                     self.build_reduced_graph_for_external_crate(module);
 266                 }
 267             }
 268
 269             ItemMod(..) => {
 270                 let parent_link = ModuleParentLink(parent, name);
 271                 let def = Def::Mod(self.ast_map.local_def_id(item.id));
 272                 let module = self.new_module(parent_link, Some(def), false, vis);
 273                 self.define(parent, name, TypeNS, (module, sp));
 274                 parent.module_children.borrow_mut().insert(item.id, module);
 275                 *parent_ref = module;
 276             }
 277
 278             ItemForeignMod(..) => {}
 279
 280             // These items live in the value namespace.
 281             ItemStatic(_, m, _) => {
 282                 let mutbl = m == hir::MutMutable;
 283                 let def = Def::Static(self.ast_map.local_def_id(item.id), mutbl);
 284                 self.define(parent, name, ValueNS, (def, sp, vis));
 285             }
 286             ItemConst(_, _) => {
 287                 let def = Def::Const(self.ast_map.local_def_id(item.id));
 288                 self.define(parent, name, ValueNS, (def, sp, vis));
 289             }
 290             ItemFn(_, _, _, _, _, _) => {
 291                 let def = Def::Fn(self.ast_map.local_def_id(item.id));
 292                 self.define(parent, name, ValueNS, (def, sp, vis));
 293             }
 294
 295             // These items live in the type namespace.
 296             ItemTy(..) => {
 297                 let def = Def::TyAlias(self.ast_map.local_def_id(item.id));
 298                 self.define(parent, name, TypeNS, (def, sp, vis));
 299             }
 300
 301             ItemEnum(ref enum_definition, _) => {
 302                 let parent_link = ModuleParentLink(parent, name);
 303                 let def = Def::Enum(self.ast_map.local_def_id(item.id));
 304                 let module = self.new_module(parent_link, Some(def), false, vis);
 305                 self.define(parent, name, TypeNS, (module, sp));
 306
 307                 for variant in &(*enum_definition).variants {
 308                     let item_def_id = self.ast_map.local_def_id(item.id);
 309                     self.build_reduced_graph_for_variant(variant, item_def_id, module);
 310                 }
 311             }
 312
 313             // These items live in both the type and value namespaces.
 314             ItemStruct(ref struct_def, _) => {
 315                 // Define a name in the type namespace.
 316                 let def = Def::Struct(self.ast_map.local_def_id(item.id));
 317                 self.define(parent, name, TypeNS, (def, sp, vis));
 318
 319                 // If this is a newtype or unit-like struct, define a name
 320                 // in the value namespace as well
 321                 if !struct_def.is_struct() {
 322                     let def = Def::Struct(self.ast_map.local_def_id(struct_def.id()));
 323                     self.define(parent, name, ValueNS, (def, sp, vis));
 324                 }
 325
 326                 // Record the def ID and fields of this struct.
 327                 let field_names = struct_def.fields().iter().map(|field| {
 328                     self.resolve_visibility(&field.vis);
 329                     field.name
 330                 }).collect();
 331                 let item_def_id = self.ast_map.local_def_id(item.id);
 332                 self.structs.insert(item_def_id, field_names);
 333             }
 334
 335             ItemDefaultImpl(_, _) | ItemImpl(..) => {}
 336
 337             ItemTrait(_, _, _, ref items) => {
 338                 let def_id = self.ast_map.local_def_id(item.id);
 339
 340                 // Add all the items within to a new module.
 341                 let parent_link = ModuleParentLink(parent, name);
 342                 let def = Def::Trait(def_id);
 343                 let module_parent = self.new_module(parent_link, Some(def), false, vis);
 344                 self.define(parent, name, TypeNS, (module_parent, sp));
 345
 346                 // Add the names of all the items to the trait info.
 347                 for item in items {
 348                     let item_def_id = self.ast_map.local_def_id(item.id);
 349                     let (def, ns) = match item.node {
 350                         hir::ConstTraitItem(..) => (Def::AssociatedConst(item_def_id), ValueNS),
 351                         hir::MethodTraitItem(..) => (Def::Method(item_def_id), ValueNS),
 352                         hir::TypeTraitItem(..) => (Def::AssociatedTy(def_id, item_def_id), TypeNS),
 353                     };
 354
 355                     self.define(module_parent, item.name, ns, (def, item.span, vis));
 356
 357                     self.trait_item_map.insert((item.name, def_id), item_def_id);
 358                 }
 359             }
 360         }
 361     }
 362
 363     // Constructs the reduced graph for one variant. Variants exist in the
 364     // type and value namespaces.
 365     fn build_reduced_graph_for_variant(&mut self,
 366                                        variant: &Variant,
 367                                        item_id: DefId,
 368                                        parent: Module<'b>) {
 369         let name = variant.node.name;
 370         if variant.node.data.is_struct() {
 371             // Not adding fields for variants as they are not accessed with a self receiver
 372             let variant_def_id = self.ast_map.local_def_id(variant.node.data.id());
 373             self.structs.insert(variant_def_id, Vec::new());
 374         }
 375
 376         // Variants are always treated as importable to allow them to be glob used.
 377         // All variants are defined in both type and value namespaces as future-proofing.
 378         let def = Def::Variant(item_id, self.ast_map.local_def_id(variant.node.data.id()));
 379         self.define(parent, name, ValueNS, (def, variant.span, parent.vis));
 380         self.define(parent, name, TypeNS, (def, variant.span, parent.vis));
 381     }
 382
 383     /// Constructs the reduced graph for one foreign item.
 384     fn build_reduced_graph_for_foreign_item(&mut self,
 385                                             foreign_item: &ForeignItem,
 386                                             parent: Module<'b>) {
 387         let name = foreign_item.name;
 388
 389         let def = match foreign_item.node {
 390             ForeignItemFn(..) => {
 391                 Def::Fn(self.ast_map.local_def_id(foreign_item.id))
 392             }
 393             ForeignItemStatic(_, m) => {
 394                 Def::Static(self.ast_map.local_def_id(foreign_item.id), m)
 395             }
 396         };
 397         self.current_module = parent;
 398         let vis = self.resolve_visibility(&foreign_item.vis);
 399         self.define(parent, name, ValueNS, (def, foreign_item.span, vis));
 400     }
 401
 402     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &mut Module<'b>) {
 403         if self.block_needs_anonymous_module(block) {
 404             let block_id = block.id;
 405
 406             debug!("(building reduced graph for block) creating a new anonymous module for block \
 407                     {}",
 408                    block_id);
 409
 410             let parent_link = BlockParentLink(parent, block_id);
 411             let new_module = self.new_module(parent_link, None, false, parent.vis);
 412             parent.module_children.borrow_mut().insert(block_id, new_module);
 413             *parent = new_module;
 414         }
 415     }
 416
 417     /// Builds the reduced graph for a single item in an external crate.
 418     fn build_reduced_graph_for_external_crate_def(&mut self, parent: Module<'b>, xcdef: ChildItem) {
 419         let def = match xcdef.def {
 420             DlDef(def) => def,
 421             _ => return,
 422         };
 423
 424         if let Def::ForeignMod(def_id) = def {
 425             // Foreign modules have no names. Recur and populate eagerly.
 426             for child in self.session.cstore.item_children(def_id) {
 427                 self.build_reduced_graph_for_external_crate_def(parent, child);
 428             }
 429             return;
 430         }
 431
 432         let name = xcdef.name;
 433         let vis = if parent.is_trait() { ty::Visibility::Public } else { xcdef.vis };
 434
 435         match def {
 436             Def::Mod(_) | Def::ForeignMod(_) | Def::Enum(..) => {
 437                 debug!("(building reduced graph for external crate) building module {} {:?}",
 438                        name, vis);
 439                 let parent_link = ModuleParentLink(parent, name);
 440                 let module = self.new_module(parent_link, Some(def), true, vis);
 441                 self.try_define(parent, name, TypeNS, (module, DUMMY_SP));
 442             }
 443             Def::Variant(_, variant_id) => {
 444                 debug!("(building reduced graph for external crate) building variant {}", name);
 445                 // Variants are always treated as importable to allow them to be glob used.
 446                 // All variants are defined in both type and value namespaces as future-proofing.
 447                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 448                 self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 449                 if self.session.cstore.variant_kind(variant_id) == Some(VariantKind::Struct) {
 450                     // Not adding fields for variants as they are not accessed with a self receiver
 451                     self.structs.insert(variant_id, Vec::new());
 452                 }
 453             }
 454             Def::Fn(..) |
 455             Def::Static(..) |
 456             Def::Const(..) |
 457             Def::AssociatedConst(..) |
 458             Def::Method(..) => {
 459                 debug!("(building reduced graph for external crate) building value (fn/static) {}",
 460                        name);
 461                 self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 462             }
 463             Def::Trait(def_id) => {
 464                 debug!("(building reduced graph for external crate) building type {}", name);
 465
 466                 // If this is a trait, add all the trait item names to the trait
 467                 // info.
 468
 469                 let trait_item_def_ids = self.session.cstore.trait_item_def_ids(def_id);
 470                 for trait_item_def in &trait_item_def_ids {
 471                     let trait_item_name =
 472                         self.session.cstore.item_name(trait_item_def.def_id());
 473
 474                     debug!("(building reduced graph for external crate) ... adding trait item \
 475                             '{}'",
 476                            trait_item_name);
 477
 478                     self.trait_item_map.insert((trait_item_name, def_id), trait_item_def.def_id());
 479                 }
 480
 481                 let parent_link = ModuleParentLink(parent, name);
 482                 let module = self.new_module(parent_link, Some(def), true, vis);
 483                 self.try_define(parent, name, TypeNS, (module, DUMMY_SP));
 484             }
 485             Def::TyAlias(..) | Def::AssociatedTy(..) => {
 486                 debug!("(building reduced graph for external crate) building type {}", name);
 487                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 488             }
 489             Def::Struct(def_id)
 490                 if self.session.cstore.tuple_struct_definition_if_ctor(def_id).is_none() => {
 491                 debug!("(building reduced graph for external crate) building type and value for {}",
 492                        name);
 493                 self.try_define(parent, name, TypeNS, (def, DUMMY_SP, vis));
 494                 if let Some(ctor_def_id) = self.session.cstore.struct_ctor_def_id(def_id) {
 495                     let def = Def::Struct(ctor_def_id);
 496                     self.try_define(parent, name, ValueNS, (def, DUMMY_SP, vis));
 497                 }
 498
 499                 // Record the def ID and fields of this struct.
 500                 let fields = self.session.cstore.struct_field_names(def_id);
 501                 self.structs.insert(def_id, fields);
 502             }
 503             Def::Struct(..) => {}
 504             Def::Local(..) |
 505             Def::PrimTy(..) |
 506             Def::TyParam(..) |
 507             Def::Upvar(..) |
 508             Def::Label(..) |
 509             Def::SelfTy(..) |
 510             Def::Err => {
 511                 bug!("didn't expect `{:?}`", def);
 512             }
 513         }
 514     }
 515
 516     /// Builds the reduced graph rooted at the 'use' directive for an external
 517     /// crate.
 518     fn build_reduced_graph_for_external_crate(&mut self, root: Module<'b>) {
 519         let root_cnum = root.def_id().unwrap().krate;
 520         for child in self.session.cstore.crate_top_level_items(root_cnum) {
 521             self.build_reduced_graph_for_external_crate_def(root, child);
 522         }
 523     }
 524
 525     /// Ensures that the reduced graph rooted at the given external module
 526     /// is built, building it if it is not.
 527     pub fn populate_module_if_necessary(&mut self, module: Module<'b>) {
 528         if module.populated.get() { return }
 529         for child in self.session.cstore.item_children(module.def_id().unwrap()) {
 530             self.build_reduced_graph_for_external_crate_def(module, child);
 531         }
 532         module.populated.set(true)
 533     }
 534 }
 535
 536 struct BuildReducedGraphVisitor<'a, 'b: 'a, 'tcx: 'b> {
 537     resolver: &'a mut Resolver<'b, 'tcx>,
 538     parent: Module<'b>,
 539 }
 540
 541 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 542     fn visit_nested_item(&mut self, item: hir::ItemId) {
 543         self.visit_item(self.resolver.ast_map.expect_item(item.id))
 544     }
 545
 546     fn visit_item(&mut self, item: &Item) {
 547         let old_parent = self.parent;
 548         self.resolver.build_reduced_graph_for_item(item, &mut self.parent);
 549         intravisit::walk_item(self, item);
 550         self.parent = old_parent;
 551     }
 552
 553     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 554         self.resolver.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 555     }
 556
 557     fn visit_block(&mut self, block: &Block) {
 558         let old_parent = self.parent;
 559         self.resolver.build_reduced_graph_for_block(block, &mut self.parent);
 560         intravisit::walk_block(self, block);
 561         self.parent = old_parent;
 562     }
 563 }