src/librustc_resolve/lib.rs

   1 // Copyright 2012-2015 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 // Do not remove on snapshot creation. Needed for bootstrap. (Issue #22364)
  12 #![cfg_attr(stage0, feature(custom_attribute))]
  13 #![crate_name = "rustc_resolve"]
  14 #![unstable(feature = "rustc_private", issue = "27812")]
  15 #![staged_api]
  16 #![crate_type = "dylib"]
  17 #![crate_type = "rlib"]
  18 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  19       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  20       html_root_url = "https://doc.rust-lang.org/nightly/")]
  21
  22 #![feature(associated_consts)]
  23 #![feature(borrow_state)]
  24 #![feature(rustc_diagnostic_macros)]
  25 #![feature(rustc_private)]
  26 #![feature(slice_splits)]
  27 #![feature(staged_api)]
  28
  29 #[macro_use] extern crate log;
  30 #[macro_use] extern crate syntax;
  31 #[macro_use] #[no_link] extern crate rustc_bitflags;
  32 extern crate rustc_front;
  33
  34 extern crate rustc;
  35
  36 use self::PatternBindingMode::*;
  37 use self::Namespace::*;
  38 use self::NamespaceResult::*;
  39 use self::NameDefinition::*;
  40 use self::ResolveResult::*;
  41 use self::FallbackSuggestion::*;
  42 use self::TypeParameters::*;
  43 use self::RibKind::*;
  44 use self::UseLexicalScopeFlag::*;
  45 use self::ModulePrefixResult::*;
  46 use self::AssocItemResolveResult::*;
  47 use self::NameSearchType::*;
  48 use self::BareIdentifierPatternResolution::*;
  49 use self::ParentLink::*;
  50 use self::ModuleKind::*;
  51 use self::FallbackChecks::*;
  52
  53 use rustc::front::map as hir_map;
  54 use rustc::session::Session;
  55 use rustc::lint;
  56 use rustc::metadata::csearch;
  57 use rustc::metadata::decoder::{DefLike, DlDef, DlField, DlImpl};
  58 use rustc::middle::def::*;
  59 use rustc::middle::def_id::DefId;
  60 use rustc::middle::pat_util::pat_bindings_hygienic;
  61 use rustc::middle::privacy::*;
  62 use rustc::middle::subst::{ParamSpace, FnSpace, TypeSpace};
  63 use rustc::middle::ty::{Freevar, FreevarMap, TraitMap, GlobMap};
  64 use rustc::util::nodemap::{NodeMap, DefIdSet, FnvHashMap};
  65 use rustc::util::lev_distance::lev_distance;
  66
  67 use syntax::ast;
  68 use syntax::ast::{CRATE_NODE_ID, Ident, Name, NodeId, CrateNum, TyIs, TyI8, TyI16, TyI32, TyI64};
  69 use syntax::ast::{TyUs, TyU8, TyU16, TyU32, TyU64, TyF64, TyF32};
  70 use syntax::attr::AttrMetaMethods;
  71 use syntax::ext::mtwt;
  72 use syntax::parse::token::{self, special_names, special_idents};
  73 use syntax::ptr::P;
  74 use syntax::codemap::{self, Span, Pos};
  75
  76 use rustc_front::visit::{self, FnKind, Visitor};
  77 use rustc_front::hir;
  78 use rustc_front::hir::{Arm, BindByRef, BindByValue, BindingMode, Block};
  79 use rustc_front::hir::{ConstImplItem, Crate};
  80 use rustc_front::hir::{Expr, ExprAgain, ExprBreak, ExprField};
  81 use rustc_front::hir::{ExprLoop, ExprWhile, ExprMethodCall};
  82 use rustc_front::hir::{ExprPath, ExprStruct, FnDecl};
  83 use rustc_front::hir::{ForeignItemFn, ForeignItemStatic, Generics};
  84 use rustc_front::hir::{ImplItem, Item, ItemConst, ItemEnum, ItemExternCrate};
  85 use rustc_front::hir::{ItemFn, ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  86 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  87 use rustc_front::hir::{Local, MethodImplItem};
  88 use rustc_front::hir::{Pat, PatEnum, PatIdent, PatLit, PatQPath};
  89 use rustc_front::hir::{PatRange, PatStruct, Path, PrimTy};
  90 use rustc_front::hir::{TraitRef, Ty, TyBool, TyChar, TyFloat, TyInt};
  91 use rustc_front::hir::{TyRptr, TyStr, TyUint, TyPath, TyPtr};
  92 use rustc_front::hir::TypeImplItem;
  93 use rustc_front::util::walk_pat;
  94
  95 use std::collections::{HashMap, HashSet};
  96 use std::cell::{Cell, RefCell};
  97 use std::fmt;
  98 use std::mem::replace;
  99 use std::rc::{Rc, Weak};
 100 use std::usize;
 101
 102 use resolve_imports::{Target, ImportDirective, ImportResolution};
 103 use resolve_imports::Shadowable;
 104
 105 // NB: This module needs to be declared first so diagnostics are
 106 // registered before they are used.
 107 pub mod diagnostics;
 108
 109 mod check_unused;
 110 mod record_exports;
 111 mod build_reduced_graph;
 112 mod resolve_imports;
 113
 114 // Perform the callback, not walking deeper if the return is true
 115 macro_rules! execute_callback {
 116     ($node: expr, $walker: expr) => (
 117         if let Some(ref callback) = $walker.callback {
 118             if callback($node, &mut $walker.resolved) {
 119                 return;
 120             }
 121         }
 122     )
 123 }
 124
 125 pub enum ResolutionError<'a> {
 126     /// error E0401: can't use type parameters from outer function
 127     TypeParametersFromOuterFunction,
 128     /// error E0402: cannot use an outer type parameter in this context
 129     OuterTypeParameterContext,
 130     /// error E0403: the name is already used for a type parameter in this type parameter list
 131     NameAlreadyUsedInTypeParameterList(Name),
 132     /// error E0404: is not a trait
 133     IsNotATrait(&'a str),
 134     /// error E0405: use of undeclared trait name
 135     UndeclaredTraitName(&'a str),
 136     /// error E0406: undeclared associated type
 137     UndeclaredAssociatedType,
 138     /// error E0407: method is not a member of trait
 139     MethodNotMemberOfTrait(Name, &'a str),
 140     /// error E0437: type is not a member of trait
 141     TypeNotMemberOfTrait(Name, &'a str),
 142     /// error E0438: const is not a member of trait
 143     ConstNotMemberOfTrait(Name, &'a str),
 144     /// error E0408: variable `{}` from pattern #1 is not bound in pattern
 145     VariableNotBoundInPattern(Name, usize),
 146     /// error E0409: variable is bound with different mode in pattern #{} than in pattern #1
 147     VariableBoundWithDifferentMode(Name, usize),
 148     /// error E0410: variable from pattern is not bound in pattern #1
 149     VariableNotBoundInParentPattern(Name, usize),
 150     /// error E0411: use of `Self` outside of an impl or trait
 151     SelfUsedOutsideImplOrTrait,
 152     /// error E0412: use of undeclared
 153     UseOfUndeclared(&'a str, &'a str),
 154     /// error E0413: declaration shadows an enum variant or unit-like struct in scope
 155     DeclarationShadowsEnumVariantOrUnitLikeStruct(Name),
 156     /// error E0414: only irrefutable patterns allowed here
 157     OnlyIrrefutablePatternsAllowedHere,
 158     /// error E0415: identifier is bound more than once in this parameter list
 159     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 160     /// error E0416: identifier is bound more than once in the same pattern
 161     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 162     /// error E0417: static variables cannot be referenced in a pattern
 163     StaticVariableReference,
 164     /// error E0418: is not an enum variant, struct or const
 165     NotAnEnumVariantStructOrConst(&'a str),
 166     /// error E0419: unresolved enum variant, struct or const
 167     UnresolvedEnumVariantStructOrConst(&'a str),
 168     /// error E0420: is not an associated const
 169     NotAnAssociatedConst(&'a str),
 170     /// error E0421: unresolved associated const
 171     UnresolvedAssociatedConst(&'a str),
 172     /// error E0422: does not name a struct
 173     DoesNotNameAStruct(&'a str),
 174     /// error E0423: is a struct variant name, but this expression uses it like a function name
 175     StructVariantUsedAsFunction(&'a str),
 176     /// error E0424: `self` is not available in a static method
 177     SelfNotAvailableInStaticMethod,
 178     /// error E0425: unresolved name
 179     UnresolvedName(&'a str, &'a str),
 180     /// error E0426: use of undeclared label
 181     UndeclaredLabel(&'a str),
 182     /// error E0427: cannot use `ref` binding mode with ...
 183     CannotUseRefBindingModeWith(&'a str),
 184     /// error E0428: duplicate definition
 185     DuplicateDefinition(&'a str, Name),
 186     /// error E0429: `self` imports are only allowed within a { } list
 187     SelfImportsOnlyAllowedWithin,
 188     /// error E0430: `self` import can only appear once in the list
 189     SelfImportCanOnlyAppearOnceInTheList,
 190     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 191     SelfImportOnlyInImportListWithNonEmptyPrefix,
 192     /// error E0432: unresolved import
 193     UnresolvedImport(Option<(&'a str, &'a str)>),
 194     /// error E0433: failed to resolve
 195     FailedToResolve(&'a str),
 196     /// error E0434: can't capture dynamic environment in a fn item
 197     CannotCaptureDynamicEnvironmentInFnItem,
 198     /// error E0435: attempt to use a non-constant value in a constant
 199     AttemptToUseNonConstantValueInConstant,
 200 }
 201
 202 fn resolve_error<'b, 'a:'b, 'tcx:'a>(resolver: &'b Resolver<'a, 'tcx>, span: syntax::codemap::Span,
 203                                      resolution_error: ResolutionError<'b>) {
 204     if !resolver.emit_errors {
 205         return;
 206     }
 207     match resolution_error {
 208         ResolutionError::TypeParametersFromOuterFunction => {
 209             span_err!(resolver.session, span, E0401, "can't use type parameters from \
 210                                                       outer function; try using a local \
 211                                                       type parameter instead");
 212         },
 213         ResolutionError::OuterTypeParameterContext => {
 214             span_err!(resolver.session, span, E0402,
 215                          "cannot use an outer type parameter in this context");
 216         },
 217         ResolutionError::NameAlreadyUsedInTypeParameterList(name) => {
 218             span_err!(resolver.session, span, E0403,
 219                          "the name `{}` is already used for a type \
 220                           parameter in this type parameter list", name);
 221         },
 222         ResolutionError::IsNotATrait(name) => {
 223             span_err!(resolver.session, span, E0404,
 224                          "`{}` is not a trait",
 225                          name);
 226         },
 227         ResolutionError::UndeclaredTraitName(name) => {
 228             span_err!(resolver.session, span, E0405,
 229                          "use of undeclared trait name `{}`",
 230                          name);
 231         },
 232         ResolutionError::UndeclaredAssociatedType => {
 233             span_err!(resolver.session, span, E0406, "undeclared associated type");
 234         },
 235         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 236             span_err!(resolver.session, span, E0407,
 237                          "method `{}` is not a member of trait `{}`",
 238                          method,
 239                          trait_);
 240         },
 241         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 242             span_err!(resolver.session, span, E0437,
 243                          "type `{}` is not a member of trait `{}`",
 244                          type_,
 245                          trait_);
 246         },
 247         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 248             span_err!(resolver.session, span, E0438,
 249                          "const `{}` is not a member of trait `{}`",
 250                          const_,
 251                          trait_);
 252         },
 253         ResolutionError::VariableNotBoundInPattern(variable_name, pattern_number) => {
 254             span_err!(resolver.session, span, E0408,
 255                          "variable `{}` from pattern #1 is not bound in pattern #{}",
 256                          variable_name,
 257                          pattern_number);
 258         },
 259         ResolutionError::VariableBoundWithDifferentMode(variable_name, pattern_number) => {
 260             span_err!(resolver.session, span, E0409,
 261                          "variable `{}` is bound with different \
 262                          mode in pattern #{} than in pattern #1",
 263                          variable_name,
 264                          pattern_number);
 265         },
 266         ResolutionError::VariableNotBoundInParentPattern(variable_name, pattern_number) => {
 267             span_err!(resolver.session, span, E0410,
 268                          "variable `{}` from pattern #{} is not bound in pattern #1",
 269                          variable_name,
 270                          pattern_number);
 271         },
 272         ResolutionError::SelfUsedOutsideImplOrTrait => {
 273             span_err!(resolver.session, span, E0411, "use of `Self` outside of an impl or trait");
 274         },
 275         ResolutionError::UseOfUndeclared(kind, name) => {
 276             span_err!(resolver.session, span, E0412,
 277                          "use of undeclared {} `{}`",
 278                          kind,
 279                          name);
 280         },
 281         ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(name) => {
 282             span_err!(resolver.session, span, E0413,
 283                          "declaration of `{}` shadows an enum variant or unit-like struct in \
 284                           scope",
 285                          name);
 286         },
 287         ResolutionError::OnlyIrrefutablePatternsAllowedHere => {
 288             span_err!(resolver.session, span, E0414, "only irrefutable patterns allowed here");
 289         },
 290         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 291             span_err!(resolver.session, span, E0415,
 292                          "identifier `{}` is bound more than once in this parameter list",
 293                          identifier);
 294         },
 295         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 296             span_err!(resolver.session, span, E0416,
 297                          "identifier `{}` is bound more than once in the same pattern",
 298                          identifier);
 299         },
 300         ResolutionError::StaticVariableReference => {
 301             span_err!(resolver.session, span, E0417, "static variables cannot be \
 302                                                       referenced in a pattern, \
 303                                                       use a `const` instead");
 304         },
 305         ResolutionError::NotAnEnumVariantStructOrConst(name) => {
 306             span_err!(resolver.session, span, E0418,
 307                          "`{}` is not an enum variant, struct or const",
 308                          name);
 309         },
 310         ResolutionError::UnresolvedEnumVariantStructOrConst(name) => {
 311             span_err!(resolver.session, span, E0419,
 312                          "unresolved enum variant, struct or const `{}`",
 313                          name);
 314         },
 315         ResolutionError::NotAnAssociatedConst(name) => {
 316             span_err!(resolver.session, span, E0420,
 317                          "`{}` is not an associated const",
 318                          name);
 319         },
 320         ResolutionError::UnresolvedAssociatedConst(name) => {
 321             span_err!(resolver.session, span, E0421,
 322                          "unresolved associated const `{}`",
 323                          name);
 324         },
 325         ResolutionError::DoesNotNameAStruct(name) => {
 326             span_err!(resolver.session, span, E0422, "`{}` does not name a structure", name);
 327         },
 328         ResolutionError::StructVariantUsedAsFunction(path_name) => {
 329             span_err!(resolver.session, span, E0423,
 330                          "`{}` is the name of a struct or struct variant, \
 331                           but this expression \
 332                           uses it like a function name",
 333                           path_name);
 334         },
 335         ResolutionError::SelfNotAvailableInStaticMethod => {
 336             span_err!(resolver.session, span, E0424, "`self` is not available in a static method. \
 337                                                       Maybe a `self` argument is missing?");
 338         },
 339         ResolutionError::UnresolvedName(path, name) => {
 340             span_err!(resolver.session, span, E0425,
 341                          "unresolved name `{}`{}",
 342                          path,
 343                          name);
 344         },
 345         ResolutionError::UndeclaredLabel(name) => {
 346             span_err!(resolver.session, span, E0426,
 347                          "use of undeclared label `{}`",
 348                          name);
 349         },
 350         ResolutionError::CannotUseRefBindingModeWith(descr) => {
 351             span_err!(resolver.session, span, E0427,
 352                          "cannot use `ref` binding mode with {}",
 353                          descr);
 354         },
 355         ResolutionError::DuplicateDefinition(namespace, name) => {
 356             span_err!(resolver.session, span, E0428,
 357                          "duplicate definition of {} `{}`",
 358                          namespace,
 359                          name);
 360         },
 361         ResolutionError::SelfImportsOnlyAllowedWithin => {
 362             span_err!(resolver.session, span, E0429, "{}",
 363                          "`self` imports are only allowed within a { } list");
 364         },
 365         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 366             span_err!(resolver.session, span, E0430,
 367                          "`self` import can only appear once in the list");
 368         },
 369         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 370             span_err!(resolver.session, span, E0431,
 371                          "`self` import can only appear in an import list with a \
 372                           non-empty prefix");
 373         }
 374         ResolutionError::UnresolvedImport(name) => {
 375             let msg = match name {
 376                 Some((n, p)) => format!("unresolved import `{}`{}", n, p),
 377                 None => "unresolved import".to_owned()
 378             };
 379             span_err!(resolver.session, span, E0432, "{}", msg);
 380         },
 381         ResolutionError::FailedToResolve(msg) => {
 382             span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg);
 383         },
 384         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 385             span_err!(resolver.session, span, E0434, "{}",
 386                          "can't capture dynamic environment in a fn item; \
 387                           use the || { ... } closure form instead");
 388         },
 389         ResolutionError::AttemptToUseNonConstantValueInConstant =>{
 390             span_err!(resolver.session, span, E0435,
 391                          "attempt to use a non-constant value in a constant");
 392         },
 393     }
 394 }
 395
 396 #[derive(Copy, Clone)]
 397 struct BindingInfo {
 398     span: Span,
 399     binding_mode: BindingMode,
 400 }
 401
 402 // Map from the name in a pattern to its binding mode.
 403 type BindingMap = HashMap<Name, BindingInfo>;
 404
 405 #[derive(Copy, Clone, PartialEq)]
 406 enum PatternBindingMode {
 407     RefutableMode,
 408     LocalIrrefutableMode,
 409     ArgumentIrrefutableMode,
 410 }
 411
 412 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 413 pub enum Namespace {
 414     TypeNS,
 415     ValueNS
 416 }
 417
 418 /// A NamespaceResult represents the result of resolving an import in
 419 /// a particular namespace. The result is either definitely-resolved,
 420 /// definitely- unresolved, or unknown.
 421 #[derive(Clone)]
 422 enum NamespaceResult {
 423     /// Means that resolve hasn't gathered enough information yet to determine
 424     /// whether the name is bound in this namespace. (That is, it hasn't
 425     /// resolved all `use` directives yet.)
 426     UnknownResult,
 427     /// Means that resolve has determined that the name is definitely
 428     /// not bound in the namespace.
 429     UnboundResult,
 430     /// Means that resolve has determined that the name is bound in the Module
 431     /// argument, and specified by the NameBindings argument.
 432     BoundResult(Rc<Module>, Rc<NameBindings>)
 433 }
 434
 435 impl NamespaceResult {
 436     fn is_unknown(&self) -> bool {
 437         match *self {
 438             UnknownResult => true,
 439             _ => false
 440         }
 441     }
 442     fn is_unbound(&self) -> bool {
 443         match *self {
 444             UnboundResult => true,
 445             _ => false
 446         }
 447     }
 448 }
 449
 450 enum NameDefinition {
 451     // The name was unbound.
 452     NoNameDefinition,
 453     // The name identifies an immediate child.
 454     ChildNameDefinition(Def, LastPrivate),
 455     // The name identifies an import.
 456     ImportNameDefinition(Def, LastPrivate),
 457 }
 458
 459 impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
 460     fn visit_item(&mut self, item: &Item) {
 461         execute_callback!(hir_map::Node::NodeItem(item), self);
 462         self.resolve_item(item);
 463     }
 464     fn visit_arm(&mut self, arm: &Arm) {
 465         self.resolve_arm(arm);
 466     }
 467     fn visit_block(&mut self, block: &Block) {
 468         execute_callback!(hir_map::Node::NodeBlock(block), self);
 469         self.resolve_block(block);
 470     }
 471     fn visit_expr(&mut self, expr: &Expr) {
 472         execute_callback!(hir_map::Node::NodeExpr(expr), self);
 473         self.resolve_expr(expr);
 474     }
 475     fn visit_local(&mut self, local: &Local) {
 476         execute_callback!(hir_map::Node::NodeLocal(&*local.pat), self);
 477         self.resolve_local(local);
 478     }
 479     fn visit_ty(&mut self, ty: &Ty) {
 480         self.resolve_type(ty);
 481     }
 482     fn visit_generics(&mut self, generics: &Generics) {
 483         self.resolve_generics(generics);
 484     }
 485     fn visit_poly_trait_ref(&mut self,
 486                             tref: &hir::PolyTraitRef,
 487                             m: &hir::TraitBoundModifier) {
 488         match self.resolve_trait_reference(tref.trait_ref.ref_id, &tref.trait_ref.path, 0) {
 489             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
 490             Err(_) => { /* error already reported */ }
 491         }
 492         visit::walk_poly_trait_ref(self, tref, m);
 493     }
 494     fn visit_variant(&mut self, variant: &hir::Variant, generics: &Generics) {
 495         execute_callback!(hir_map::Node::NodeVariant(variant), self);
 496         if let Some(ref dis_expr) = variant.node.disr_expr {
 497             // resolve the discriminator expr as a constant
 498             self.with_constant_rib(|this| {
 499                 this.visit_expr(&**dis_expr);
 500             });
 501         }
 502
 503         // `visit::walk_variant` without the discriminant expression.
 504         match variant.node.kind {
 505             hir::TupleVariantKind(ref variant_arguments) => {
 506                 for variant_argument in variant_arguments {
 507                     self.visit_ty(&*variant_argument.ty);
 508                 }
 509             }
 510             hir::StructVariantKind(ref struct_definition) => {
 511                 self.visit_struct_def(&**struct_definition,
 512                                       variant.node.name,
 513                                       generics,
 514                                       variant.node.id);
 515             }
 516         }
 517     }
 518     fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem) {
 519         execute_callback!(hir_map::Node::NodeForeignItem(foreign_item), self);
 520         let type_parameters = match foreign_item.node {
 521             ForeignItemFn(_, ref generics) => {
 522                 HasTypeParameters(generics, FnSpace, ItemRibKind)
 523             }
 524             ForeignItemStatic(..) => NoTypeParameters
 525         };
 526         self.with_type_parameter_rib(type_parameters, |this| {
 527             visit::walk_foreign_item(this, foreign_item);
 528         });
 529     }
 530     fn visit_fn(&mut self,
 531                 function_kind: FnKind<'v>,
 532                 declaration: &'v FnDecl,
 533                 block: &'v Block,
 534                 _: Span,
 535                 node_id: NodeId) {
 536         let rib_kind = match function_kind {
 537             FnKind::ItemFn(_, generics, _, _, _, _) => {
 538                 self.visit_generics(generics);
 539                 ItemRibKind
 540             }
 541             FnKind::Method(_, sig, _) => {
 542                 self.visit_generics(&sig.generics);
 543                 self.visit_explicit_self(&sig.explicit_self);
 544                 MethodRibKind
 545             }
 546             FnKind::Closure(..) => ClosureRibKind(node_id)
 547         };
 548         self.resolve_function(rib_kind, declaration, block);
 549     }
 550 }
 551
 552 type ErrorMessage = Option<(Span, String)>;
 553
 554 enum ResolveResult<T> {
 555     Failed(ErrorMessage),   // Failed to resolve the name, optional helpful error message.
 556     Indeterminate,          // Couldn't determine due to unresolved globs.
 557     Success(T)              // Successfully resolved the import.
 558 }
 559
 560 impl<T> ResolveResult<T> {
 561     fn success(&self) -> bool {
 562         match *self { Success(_) => true, _ => false }
 563     }
 564 }
 565
 566 enum FallbackSuggestion {
 567     NoSuggestion,
 568     Field,
 569     Method,
 570     TraitItem,
 571     StaticMethod(String),
 572     TraitMethod(String),
 573 }
 574
 575 #[derive(Copy, Clone)]
 576 enum TypeParameters<'a> {
 577     NoTypeParameters,
 578     HasTypeParameters(
 579         // Type parameters.
 580         &'a Generics,
 581
 582         // Identifies the things that these parameters
 583         // were declared on (type, fn, etc)
 584         ParamSpace,
 585
 586         // The kind of the rib used for type parameters.
 587         RibKind)
 588 }
 589
 590 // The rib kind controls the translation of local
 591 // definitions (`DefLocal`) to upvars (`DefUpvar`).
 592 #[derive(Copy, Clone, Debug)]
 593 enum RibKind {
 594     // No translation needs to be applied.
 595     NormalRibKind,
 596
 597     // We passed through a closure scope at the given node ID.
 598     // Translate upvars as appropriate.
 599     ClosureRibKind(NodeId /* func id */),
 600
 601     // We passed through an impl or trait and are now in one of its
 602     // methods. Allow references to ty params that impl or trait
 603     // binds. Disallow any other upvars (including other ty params that are
 604     // upvars).
 605     MethodRibKind,
 606
 607     // We passed through an item scope. Disallow upvars.
 608     ItemRibKind,
 609
 610     // We're in a constant item. Can't refer to dynamic stuff.
 611     ConstantItemRibKind
 612 }
 613
 614 #[derive(Copy, Clone)]
 615 enum UseLexicalScopeFlag {
 616     DontUseLexicalScope,
 617     UseLexicalScope
 618 }
 619
 620 enum ModulePrefixResult {
 621     NoPrefixFound,
 622     PrefixFound(Rc<Module>, usize)
 623 }
 624
 625 #[derive(Copy, Clone)]
 626 enum AssocItemResolveResult {
 627     /// Syntax such as `<T>::item`, which can't be resolved until type
 628     /// checking.
 629     TypecheckRequired,
 630     /// We should have been able to resolve the associated item.
 631     ResolveAttempt(Option<PathResolution>),
 632 }
 633
 634 #[derive(Copy, Clone, PartialEq)]
 635 enum NameSearchType {
 636     /// We're doing a name search in order to resolve a `use` directive.
 637     ImportSearch,
 638
 639     /// We're doing a name search in order to resolve a path type, a path
 640     /// expression, or a path pattern.
 641     PathSearch,
 642 }
 643
 644 #[derive(Copy, Clone)]
 645 enum BareIdentifierPatternResolution {
 646     FoundStructOrEnumVariant(Def, LastPrivate),
 647     FoundConst(Def, LastPrivate),
 648     BareIdentifierPatternUnresolved
 649 }
 650
 651 /// One local scope.
 652 #[derive(Debug)]
 653 struct Rib {
 654     bindings: HashMap<Name, DefLike>,
 655     kind: RibKind,
 656 }
 657
 658 impl Rib {
 659     fn new(kind: RibKind) -> Rib {
 660         Rib {
 661             bindings: HashMap::new(),
 662             kind: kind
 663         }
 664     }
 665 }
 666
 667 /// The link from a module up to its nearest parent node.
 668 #[derive(Clone,Debug)]
 669 enum ParentLink {
 670     NoParentLink,
 671     ModuleParentLink(Weak<Module>, Name),
 672     BlockParentLink(Weak<Module>, NodeId)
 673 }
 674
 675 /// The type of module this is.
 676 #[derive(Copy, Clone, PartialEq, Debug)]
 677 enum ModuleKind {
 678     NormalModuleKind,
 679     TraitModuleKind,
 680     EnumModuleKind,
 681     TypeModuleKind,
 682     AnonymousModuleKind,
 683 }
 684
 685 /// One node in the tree of modules.
 686 pub struct Module {
 687     parent_link: ParentLink,
 688     def_id: Cell<Option<DefId>>,
 689     kind: Cell<ModuleKind>,
 690     is_public: bool,
 691
 692     children: RefCell<HashMap<Name, Rc<NameBindings>>>,
 693     imports: RefCell<Vec<ImportDirective>>,
 694
 695     // The external module children of this node that were declared with
 696     // `extern crate`.
 697     external_module_children: RefCell<HashMap<Name, Rc<Module>>>,
 698
 699     // The anonymous children of this node. Anonymous children are pseudo-
 700     // modules that are implicitly created around items contained within
 701     // blocks.
 702     //
 703     // For example, if we have this:
 704     //
 705     //  fn f() {
 706     //      fn g() {
 707     //          ...
 708     //      }
 709     //  }
 710     //
 711     // There will be an anonymous module created around `g` with the ID of the
 712     // entry block for `f`.
 713     anonymous_children: RefCell<NodeMap<Rc<Module>>>,
 714
 715     // The status of resolving each import in this module.
 716     import_resolutions: RefCell<HashMap<Name, ImportResolution>>,
 717
 718     // The number of unresolved globs that this module exports.
 719     glob_count: Cell<usize>,
 720
 721     // The number of unresolved pub imports (both regular and globs) in this module
 722     pub_count: Cell<usize>,
 723
 724     // The number of unresolved pub glob imports in this module
 725     pub_glob_count: Cell<usize>,
 726
 727     // The index of the import we're resolving.
 728     resolved_import_count: Cell<usize>,
 729
 730     // Whether this module is populated. If not populated, any attempt to
 731     // access the children must be preceded with a
 732     // `populate_module_if_necessary` call.
 733     populated: Cell<bool>,
 734 }
 735
 736 impl Module {
 737     fn new(parent_link: ParentLink,
 738            def_id: Option<DefId>,
 739            kind: ModuleKind,
 740            external: bool,
 741            is_public: bool)
 742            -> Module {
 743         Module {
 744             parent_link: parent_link,
 745             def_id: Cell::new(def_id),
 746             kind: Cell::new(kind),
 747             is_public: is_public,
 748             children: RefCell::new(HashMap::new()),
 749             imports: RefCell::new(Vec::new()),
 750             external_module_children: RefCell::new(HashMap::new()),
 751             anonymous_children: RefCell::new(NodeMap()),
 752             import_resolutions: RefCell::new(HashMap::new()),
 753             glob_count: Cell::new(0),
 754             pub_count: Cell::new(0),
 755             pub_glob_count: Cell::new(0),
 756             resolved_import_count: Cell::new(0),
 757             populated: Cell::new(!external),
 758         }
 759     }
 760
 761     fn all_imports_resolved(&self) -> bool {
 762         if self.imports.borrow_state() == ::std::cell::BorrowState::Writing {
 763             // it is currently being resolved ! so nope
 764             false
 765         } else {
 766             self.imports.borrow().len() == self.resolved_import_count.get()
 767         }
 768     }
 769 }
 770
 771 impl Module {
 772     pub fn inc_glob_count(&self) {
 773         self.glob_count.set(self.glob_count.get() + 1);
 774     }
 775     pub fn dec_glob_count(&self) {
 776         assert!(self.glob_count.get() > 0);
 777         self.glob_count.set(self.glob_count.get() - 1);
 778     }
 779     pub fn inc_pub_count(&self) {
 780         self.pub_count.set(self.pub_count.get() + 1);
 781     }
 782     pub fn dec_pub_count(&self) {
 783         assert!(self.pub_count.get() > 0);
 784         self.pub_count.set(self.pub_count.get() - 1);
 785     }
 786     pub fn inc_pub_glob_count(&self) {
 787         self.pub_glob_count.set(self.pub_glob_count.get() + 1);
 788     }
 789     pub fn dec_pub_glob_count(&self) {
 790         assert!(self.pub_glob_count.get() > 0);
 791         self.pub_glob_count.set(self.pub_glob_count.get() - 1);
 792     }
 793 }
 794
 795 impl fmt::Debug for Module {
 796     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 797         write!(f, "{:?}, kind: {:?}, {}",
 798                self.def_id,
 799                self.kind,
 800                if self.is_public { "public" } else { "private" } )
 801     }
 802 }
 803
 804 bitflags! {
 805     #[derive(Debug)]
 806     flags DefModifiers: u8 {
 807         const PUBLIC     = 1 << 0,
 808         const IMPORTABLE = 1 << 1,
 809     }
 810 }
 811
 812 // Records a possibly-private type definition.
 813 #[derive(Clone,Debug)]
 814 struct TypeNsDef {
 815     modifiers: DefModifiers, // see note in ImportResolution about how to use this
 816     module_def: Option<Rc<Module>>,
 817     type_def: Option<Def>,
 818     type_span: Option<Span>
 819 }
 820
 821 // Records a possibly-private value definition.
 822 #[derive(Clone, Copy, Debug)]
 823 struct ValueNsDef {
 824     modifiers: DefModifiers, // see note in ImportResolution about how to use this
 825     def: Def,
 826     value_span: Option<Span>,
 827 }
 828
 829 // Records the definitions (at most one for each namespace) that a name is
 830 // bound to.
 831 #[derive(Debug)]
 832 pub struct NameBindings {
 833     type_def: RefCell<Option<TypeNsDef>>,   //< Meaning in type namespace.
 834     value_def: RefCell<Option<ValueNsDef>>, //< Meaning in value namespace.
 835 }
 836
 837 impl NameBindings {
 838     fn new() -> NameBindings {
 839         NameBindings {
 840             type_def: RefCell::new(None),
 841             value_def: RefCell::new(None),
 842         }
 843     }
 844
 845     /// Creates a new module in this set of name bindings.
 846     fn define_module(&self,
 847                      parent_link: ParentLink,
 848                      def_id: Option<DefId>,
 849                      kind: ModuleKind,
 850                      external: bool,
 851                      is_public: bool,
 852                      sp: Span) {
 853         // Merges the module with the existing type def or creates a new one.
 854         let modifiers = if is_public {
 855             DefModifiers::PUBLIC
 856         } else {
 857             DefModifiers::empty()
 858         } | DefModifiers::IMPORTABLE;
 859         let module_ = Rc::new(Module::new(parent_link,
 860                                           def_id,
 861                                           kind,
 862                                           external,
 863                                           is_public));
 864         let type_def = self.type_def.borrow().clone();
 865         match type_def {
 866             None => {
 867                 *self.type_def.borrow_mut() = Some(TypeNsDef {
 868                     modifiers: modifiers,
 869                     module_def: Some(module_),
 870                     type_def: None,
 871                     type_span: Some(sp)
 872                 });
 873             }
 874             Some(type_def) => {
 875                 *self.type_def.borrow_mut() = Some(TypeNsDef {
 876                     modifiers: modifiers,
 877                     module_def: Some(module_),
 878                     type_span: Some(sp),
 879                     type_def: type_def.type_def
 880                 });
 881             }
 882         }
 883     }
 884
 885     /// Sets the kind of the module, creating a new one if necessary.
 886     fn set_module_kind(&self,
 887                        parent_link: ParentLink,
 888                        def_id: Option<DefId>,
 889                        kind: ModuleKind,
 890                        external: bool,
 891                        is_public: bool,
 892                        _sp: Span) {
 893         let modifiers = if is_public {
 894             DefModifiers::PUBLIC
 895         } else {
 896             DefModifiers::empty()
 897         } | DefModifiers::IMPORTABLE;
 898         let type_def = self.type_def.borrow().clone();
 899         match type_def {
 900             None => {
 901                 let module = Module::new(parent_link,
 902                                          def_id,
 903                                          kind,
 904                                          external,
 905                                          is_public);
 906                 *self.type_def.borrow_mut() = Some(TypeNsDef {
 907                     modifiers: modifiers,
 908                     module_def: Some(Rc::new(module)),
 909                     type_def: None,
 910                     type_span: None,
 911                 });
 912             }
 913             Some(type_def) => {
 914                 match type_def.module_def {
 915                     None => {
 916                         let module = Module::new(parent_link,
 917                                                  def_id,
 918                                                  kind,
 919                                                  external,
 920                                                  is_public);
 921                         *self.type_def.borrow_mut() = Some(TypeNsDef {
 922                             modifiers: modifiers,
 923                             module_def: Some(Rc::new(module)),
 924                             type_def: type_def.type_def,
 925                             type_span: None,
 926                         });
 927                     }
 928                     Some(module_def) => module_def.kind.set(kind),
 929                 }
 930             }
 931         }
 932     }
 933
 934     /// Records a type definition.
 935     fn define_type(&self, def: Def, sp: Span, modifiers: DefModifiers) {
 936         debug!("defining type for def {:?} with modifiers {:?}", def, modifiers);
 937         // Merges the type with the existing type def or creates a new one.
 938         let type_def = self.type_def.borrow().clone();
 939         match type_def {
 940             None => {
 941                 *self.type_def.borrow_mut() = Some(TypeNsDef {
 942                     module_def: None,
 943                     type_def: Some(def),
 944                     type_span: Some(sp),
 945                     modifiers: modifiers,
 946                 });
 947             }
 948             Some(type_def) => {
 949                 *self.type_def.borrow_mut() = Some(TypeNsDef {
 950                     module_def: type_def.module_def,
 951                     type_def: Some(def),
 952                     type_span: Some(sp),
 953                     modifiers: modifiers,
 954                 });
 955             }
 956         }
 957     }
 958
 959     /// Records a value definition.
 960     fn define_value(&self, def: Def, sp: Span, modifiers: DefModifiers) {
 961         debug!("defining value for def {:?} with modifiers {:?}", def, modifiers);
 962         *self.value_def.borrow_mut() = Some(ValueNsDef {
 963             def: def,
 964             value_span: Some(sp),
 965             modifiers: modifiers,
 966         });
 967     }
 968
 969     /// Returns the module node if applicable.
 970     fn get_module_if_available(&self) -> Option<Rc<Module>> {
 971         match *self.type_def.borrow() {
 972             Some(ref type_def) => type_def.module_def.clone(),
 973             None => None
 974         }
 975     }
 976
 977     /// Returns the module node. Panics if this node does not have a module
 978     /// definition.
 979     fn get_module(&self) -> Rc<Module> {
 980         match self.get_module_if_available() {
 981             None => {
 982                 panic!("get_module called on a node with no module \
 983                        definition!")
 984             }
 985             Some(module_def) => module_def
 986         }
 987     }
 988
 989     fn defined_in_namespace(&self, namespace: Namespace) -> bool {
 990         match namespace {
 991             TypeNS   => return self.type_def.borrow().is_some(),
 992             ValueNS  => return self.value_def.borrow().is_some()
 993         }
 994     }
 995
 996     fn defined_in_public_namespace(&self, namespace: Namespace) -> bool {
 997         self.defined_in_namespace_with(namespace, DefModifiers::PUBLIC)
 998     }
 999
1000     fn defined_in_namespace_with(&self, namespace: Namespace, modifiers: DefModifiers) -> bool {
1001         match namespace {
1002             TypeNS => match *self.type_def.borrow() {
1003                 Some(ref def) => def.modifiers.contains(modifiers), None => false
1004             },
1005             ValueNS => match *self.value_def.borrow() {
1006                 Some(ref def) => def.modifiers.contains(modifiers), None => false
1007             }
1008         }
1009     }
1010
1011     fn def_for_namespace(&self, namespace: Namespace) -> Option<Def> {
1012         match namespace {
1013             TypeNS => {
1014                 match *self.type_def.borrow() {
1015                     None => None,
1016                     Some(ref type_def) => {
1017                         match type_def.type_def {
1018                             Some(type_def) => Some(type_def),
1019                             None => {
1020                                 match type_def.module_def {
1021                                     Some(ref module) => {
1022                                         match module.def_id.get() {
1023                                             Some(did) => Some(DefMod(did)),
1024                                             None => None,
1025                                         }
1026                                     }
1027                                     None => None,
1028                                 }
1029                             }
1030                         }
1031                     }
1032                 }
1033             }
1034             ValueNS => {
1035                 match *self.value_def.borrow() {
1036                     None => None,
1037                     Some(value_def) => Some(value_def.def)
1038                 }
1039             }
1040         }
1041     }
1042
1043     fn span_for_namespace(&self, namespace: Namespace) -> Option<Span> {
1044         if self.defined_in_namespace(namespace) {
1045             match namespace {
1046                 TypeNS  => {
1047                     match *self.type_def.borrow() {
1048                         None => None,
1049                         Some(ref type_def) => type_def.type_span
1050                     }
1051                 }
1052                 ValueNS => {
1053                     match *self.value_def.borrow() {
1054                         None => None,
1055                         Some(ref value_def) => value_def.value_span
1056                     }
1057                 }
1058             }
1059         } else {
1060             None
1061         }
1062     }
1063
1064     fn is_public(&self, namespace: Namespace) -> bool {
1065         match namespace {
1066             TypeNS  => {
1067                 let type_def = self.type_def.borrow();
1068                 type_def.as_ref().unwrap().modifiers.contains(DefModifiers::PUBLIC)
1069             }
1070             ValueNS => {
1071                 let value_def = self.value_def.borrow();
1072                 value_def.as_ref().unwrap().modifiers.contains(DefModifiers::PUBLIC)
1073             }
1074         }
1075     }
1076 }
1077
1078 /// Interns the names of the primitive types.
1079 struct PrimitiveTypeTable {
1080     primitive_types: HashMap<Name, PrimTy>,
1081 }
1082
1083 impl PrimitiveTypeTable {
1084     fn new() -> PrimitiveTypeTable {
1085         let mut table = PrimitiveTypeTable {
1086             primitive_types: HashMap::new()
1087         };
1088
1089         table.intern("bool",    TyBool);
1090         table.intern("char",    TyChar);
1091         table.intern("f32",     TyFloat(TyF32));
1092         table.intern("f64",     TyFloat(TyF64));
1093         table.intern("isize",   TyInt(TyIs));
1094         table.intern("i8",      TyInt(TyI8));
1095         table.intern("i16",     TyInt(TyI16));
1096         table.intern("i32",     TyInt(TyI32));
1097         table.intern("i64",     TyInt(TyI64));
1098         table.intern("str",     TyStr);
1099         table.intern("usize",   TyUint(TyUs));
1100         table.intern("u8",      TyUint(TyU8));
1101         table.intern("u16",     TyUint(TyU16));
1102         table.intern("u32",     TyUint(TyU32));
1103         table.intern("u64",     TyUint(TyU64));
1104
1105         table
1106     }
1107
1108     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1109         self.primitive_types.insert(token::intern(string), primitive_type);
1110     }
1111 }
1112
1113 /// The main resolver class.
1114 pub struct Resolver<'a, 'tcx:'a> {
1115     session: &'a Session,
1116
1117     ast_map: &'a hir_map::Map<'tcx>,
1118
1119     graph_root: NameBindings,
1120
1121     trait_item_map: FnvHashMap<(Name, DefId), DefId>,
1122
1123     structs: FnvHashMap<DefId, Vec<Name>>,
1124
1125     // The number of imports that are currently unresolved.
1126     unresolved_imports: usize,
1127
1128     // The module that represents the current item scope.
1129     current_module: Rc<Module>,
1130
1131     // The current set of local scopes, for values.
1132     // FIXME #4948: Reuse ribs to avoid allocation.
1133     value_ribs: Vec<Rib>,
1134
1135     // The current set of local scopes, for types.
1136     type_ribs: Vec<Rib>,
1137
1138     // The current set of local scopes, for labels.
1139     label_ribs: Vec<Rib>,
1140
1141     // The trait that the current context can refer to.
1142     current_trait_ref: Option<(DefId, TraitRef)>,
1143
1144     // The current self type if inside an impl (used for better errors).
1145     current_self_type: Option<Ty>,
1146
1147     // The idents for the primitive types.
1148     primitive_type_table: PrimitiveTypeTable,
1149
1150     def_map: DefMap,
1151     freevars: RefCell<FreevarMap>,
1152     freevars_seen: RefCell<NodeMap<NodeMap<usize>>>,
1153     export_map: ExportMap,
1154     trait_map: TraitMap,
1155     external_exports: ExternalExports,
1156
1157     // Whether or not to print error messages. Can be set to true
1158     // when getting additional info for error message suggestions,
1159     // so as to avoid printing duplicate errors
1160     emit_errors: bool,
1161
1162     make_glob_map: bool,
1163     // Maps imports to the names of items actually imported (this actually maps
1164     // all imports, but only glob imports are actually interesting).
1165     glob_map: GlobMap,
1166
1167     used_imports: HashSet<(NodeId, Namespace)>,
1168     used_crates: HashSet<CrateNum>,
1169
1170     // Callback function for intercepting walks
1171     callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>,
1172     // The intention is that the callback modifies this flag.
1173     // Once set, the resolver falls out of the walk, preserving the ribs.
1174     resolved: bool,
1175
1176 }
1177
1178 #[derive(PartialEq)]
1179 enum FallbackChecks {
1180     Everything,
1181     OnlyTraitAndStatics
1182 }
1183
1184 impl<'a, 'tcx> Resolver<'a, 'tcx> {
1185     fn new(session: &'a Session,
1186            ast_map: &'a hir_map::Map<'tcx>,
1187            crate_span: Span,
1188            make_glob_map: MakeGlobMap) -> Resolver<'a, 'tcx> {
1189         let graph_root = NameBindings::new();
1190
1191         let root_def_id = ast_map.local_def_id(CRATE_NODE_ID);
1192         graph_root.define_module(NoParentLink,
1193                                  Some(root_def_id),
1194                                  NormalModuleKind,
1195                                  false,
1196                                  true,
1197                                  crate_span);
1198
1199         let current_module = graph_root.get_module();
1200
1201         Resolver {
1202             session: session,
1203
1204             ast_map: ast_map,
1205
1206             // The outermost module has def ID 0; this is not reflected in the
1207             // AST.
1208
1209             graph_root: graph_root,
1210
1211             trait_item_map: FnvHashMap(),
1212             structs: FnvHashMap(),
1213
1214             unresolved_imports: 0,
1215
1216             current_module: current_module,
1217             value_ribs: Vec::new(),
1218             type_ribs: Vec::new(),
1219             label_ribs: Vec::new(),
1220
1221             current_trait_ref: None,
1222             current_self_type: None,
1223
1224             primitive_type_table: PrimitiveTypeTable::new(),
1225
1226             def_map: RefCell::new(NodeMap()),
1227             freevars: RefCell::new(NodeMap()),
1228             freevars_seen: RefCell::new(NodeMap()),
1229             export_map: NodeMap(),
1230             trait_map: NodeMap(),
1231             used_imports: HashSet::new(),
1232             used_crates: HashSet::new(),
1233             external_exports: DefIdSet(),
1234
1235             emit_errors: true,
1236             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1237             glob_map: HashMap::new(),
1238
1239             callback: None,
1240             resolved: false,
1241
1242         }
1243     }
1244
1245     #[inline]
1246     fn record_import_use(&mut self, import_id: NodeId, name: Name) {
1247         if !self.make_glob_map {
1248             return;
1249         }
1250         if self.glob_map.contains_key(&import_id) {
1251             self.glob_map.get_mut(&import_id).unwrap().insert(name);
1252             return;
1253         }
1254
1255         let mut new_set = HashSet::new();
1256         new_set.insert(name);
1257         self.glob_map.insert(import_id, new_set);
1258     }
1259
1260     fn get_trait_name(&self, did: DefId) -> Name {
1261         if let Some(node_id) = self.ast_map.as_local_node_id(did) {
1262             self.ast_map.expect_item(node_id).name
1263         } else {
1264             csearch::get_trait_name(&self.session.cstore, did)
1265         }
1266     }
1267
1268     fn create_name_bindings_from_module(module: Rc<Module>) -> NameBindings {
1269         NameBindings {
1270             type_def: RefCell::new(Some(TypeNsDef {
1271                 modifiers: DefModifiers::IMPORTABLE,
1272                 module_def: Some(module),
1273                 type_def: None,
1274                 type_span: None
1275             })),
1276             value_def: RefCell::new(None),
1277         }
1278     }
1279
1280     /// Checks that the names of external crates don't collide with other
1281     /// external crates.
1282     fn check_for_conflicts_between_external_crates(&self,
1283                                                    module: &Module,
1284                                                    name: Name,
1285                                                    span: Span) {
1286         if module.external_module_children.borrow().contains_key(&name) {
1287                 span_err!(self.session, span, E0259,
1288                           "an external crate named `{}` has already \
1289                            been imported into this module",
1290                           name);
1291         }
1292     }
1293
1294     /// Checks that the names of items don't collide with external crates.
1295     fn check_for_conflicts_between_external_crates_and_items(&self,
1296                                                              module: &Module,
1297                                                              name: Name,
1298                                                              span: Span) {
1299         if module.external_module_children.borrow().contains_key(&name) {
1300                 span_err!(self.session, span, E0260,
1301                           "the name `{}` conflicts with an external \
1302                            crate that has been imported into this \
1303                            module",
1304                            name);
1305         }
1306     }
1307
1308     /// Resolves the given module path from the given root `module_`.
1309     fn resolve_module_path_from_root(&mut self,
1310                                      module_: Rc<Module>,
1311                                      module_path: &[Name],
1312                                      index: usize,
1313                                      span: Span,
1314                                      name_search_type: NameSearchType,
1315                                      lp: LastPrivate)
1316                                 -> ResolveResult<(Rc<Module>, LastPrivate)> {
1317         fn search_parent_externals(needle: Name, module: &Rc<Module>)
1318                                 -> Option<Rc<Module>> {
1319             match module.external_module_children.borrow().get(&needle) {
1320                 Some(_) => Some(module.clone()),
1321                 None => match module.parent_link {
1322                     ModuleParentLink(ref parent, _) => {
1323                         search_parent_externals(needle, &parent.upgrade().unwrap())
1324                     }
1325                    _ => None
1326                 }
1327             }
1328         }
1329
1330         let mut search_module = module_;
1331         let mut index = index;
1332         let module_path_len = module_path.len();
1333         let mut closest_private = lp;
1334
1335         // Resolve the module part of the path. This does not involve looking
1336         // upward though scope chains; we simply resolve names directly in
1337         // modules as we go.
1338         while index < module_path_len {
1339             let name = module_path[index];
1340             match self.resolve_name_in_module(search_module.clone(),
1341                                               name,
1342                                               TypeNS,
1343                                               name_search_type,
1344                                               false) {
1345                 Failed(None) => {
1346                     let segment_name = name.as_str();
1347                     let module_name = module_to_string(&*search_module);
1348                     let mut span = span;
1349                     let msg = if "???" == &module_name[..] {
1350                         span.hi = span.lo + Pos::from_usize(segment_name.len());
1351
1352                         match search_parent_externals(name,
1353                                                      &self.current_module) {
1354                             Some(module) => {
1355                                 let path_str = names_to_string(module_path);
1356                                 let target_mod_str = module_to_string(&*module);
1357                                 let current_mod_str =
1358                                     module_to_string(&*self.current_module);
1359
1360                                 let prefix = if target_mod_str == current_mod_str {
1361                                     "self::".to_string()
1362                                 } else {
1363                                     format!("{}::", target_mod_str)
1364                                 };
1365
1366                                 format!("Did you mean `{}{}`?", prefix, path_str)
1367                             },
1368                             None => format!("Maybe a missing `extern crate {}`?",
1369                                             segment_name),
1370                         }
1371                     } else {
1372                         format!("Could not find `{}` in `{}`",
1373                                 segment_name,
1374                                 module_name)
1375                     };
1376
1377                     return Failed(Some((span, msg)));
1378                 }
1379                 Failed(err) => return Failed(err),
1380                 Indeterminate => {
1381                     debug!("(resolving module path for import) module \
1382                             resolution is indeterminate: {}",
1383                             name);
1384                     return Indeterminate;
1385                 }
1386                 Success((target, used_proxy)) => {
1387                     // Check to see whether there are type bindings, and, if
1388                     // so, whether there is a module within.
1389                     match *target.bindings.type_def.borrow() {
1390                         Some(ref type_def) => {
1391                             match type_def.module_def {
1392                                 None => {
1393                                     let msg = format!("Not a module `{}`",
1394                                                         name);
1395
1396                                     return Failed(Some((span, msg)));
1397                                 }
1398                                 Some(ref module_def) => {
1399                                     search_module = module_def.clone();
1400
1401                                     // track extern crates for unused_extern_crate lint
1402                                     if let Some(did) = module_def.def_id.get() {
1403                                         self.used_crates.insert(did.krate);
1404                                     }
1405
1406                                     // Keep track of the closest
1407                                     // private module used when
1408                                     // resolving this import chain.
1409                                     if !used_proxy && !search_module.is_public {
1410                                         if let Some(did) = search_module.def_id.get() {
1411                                             closest_private = LastMod(DependsOn(did));
1412                                         }
1413                                     }
1414                                 }
1415                             }
1416                         }
1417                         None => {
1418                             // There are no type bindings at all.
1419                             let msg = format!("Not a module `{}`",
1420                                               name);
1421                             return Failed(Some((span, msg)));
1422                         }
1423                     }
1424                 }
1425             }
1426
1427             index += 1;
1428         }
1429
1430         return Success((search_module, closest_private));
1431     }
1432
1433     /// Attempts to resolve the module part of an import directive or path
1434     /// rooted at the given module.
1435     ///
1436     /// On success, returns the resolved module, and the closest *private*
1437     /// module found to the destination when resolving this path.
1438     fn resolve_module_path(&mut self,
1439                            module_: Rc<Module>,
1440                            module_path: &[Name],
1441                            use_lexical_scope: UseLexicalScopeFlag,
1442                            span: Span,
1443                            name_search_type: NameSearchType)
1444                            -> ResolveResult<(Rc<Module>, LastPrivate)> {
1445         let module_path_len = module_path.len();
1446         assert!(module_path_len > 0);
1447
1448         debug!("(resolving module path for import) processing `{}` rooted at `{}`",
1449                names_to_string(module_path),
1450                module_to_string(&*module_));
1451
1452         // Resolve the module prefix, if any.
1453         let module_prefix_result = self.resolve_module_prefix(module_.clone(),
1454                                                               module_path);
1455
1456         let search_module;
1457         let start_index;
1458         let last_private;
1459         match module_prefix_result {
1460             Failed(None) => {
1461                 let mpath = names_to_string(module_path);
1462                 let mpath = &mpath[..];
1463                 match mpath.rfind(':') {
1464                     Some(idx) => {
1465                         let msg = format!("Could not find `{}` in `{}`",
1466                                             // idx +- 1 to account for the
1467                                             // colons on either side
1468                                             &mpath[idx + 1..],
1469                                             &mpath[..idx - 1]);
1470                         return Failed(Some((span, msg)));
1471                     },
1472                     None => {
1473                         return Failed(None)
1474                     }
1475                 }
1476             }
1477             Failed(err) => return Failed(err),
1478             Indeterminate => {
1479                 debug!("(resolving module path for import) indeterminate; \
1480                         bailing");
1481                 return Indeterminate;
1482             }
1483             Success(NoPrefixFound) => {
1484                 // There was no prefix, so we're considering the first element
1485                 // of the path. How we handle this depends on whether we were
1486                 // instructed to use lexical scope or not.
1487                 match use_lexical_scope {
1488                     DontUseLexicalScope => {
1489                         // This is a crate-relative path. We will start the
1490                         // resolution process at index zero.
1491                         search_module = self.graph_root.get_module();
1492                         start_index = 0;
1493                         last_private = LastMod(AllPublic);
1494                     }
1495                     UseLexicalScope => {
1496                         // This is not a crate-relative path. We resolve the
1497                         // first component of the path in the current lexical
1498                         // scope and then proceed to resolve below that.
1499                         match self.resolve_module_in_lexical_scope(module_,
1500                                                                    module_path[0]) {
1501                             Failed(err) => return Failed(err),
1502                             Indeterminate => {
1503                                 debug!("(resolving module path for import) \
1504                                         indeterminate; bailing");
1505                                 return Indeterminate;
1506                             }
1507                             Success(containing_module) => {
1508                                 search_module = containing_module;
1509                                 start_index = 1;
1510                                 last_private = LastMod(AllPublic);
1511                             }
1512                         }
1513                     }
1514                 }
1515             }
1516             Success(PrefixFound(ref containing_module, index)) => {
1517                 search_module = containing_module.clone();
1518                 start_index = index;
1519                 last_private = LastMod(DependsOn(containing_module.def_id
1520                                                                   .get()
1521                                                                   .unwrap()));
1522             }
1523         }
1524
1525         self.resolve_module_path_from_root(search_module,
1526                                            module_path,
1527                                            start_index,
1528                                            span,
1529                                            name_search_type,
1530                                            last_private)
1531     }
1532
1533     /// Invariant: This must only be called during main resolution, not during
1534     /// import resolution.
1535     fn resolve_item_in_lexical_scope(&mut self,
1536                                      module_: Rc<Module>,
1537                                      name: Name,
1538                                      namespace: Namespace)
1539                                     -> ResolveResult<(Target, bool)> {
1540         debug!("(resolving item in lexical scope) resolving `{}` in \
1541                 namespace {:?} in `{}`",
1542                name,
1543                namespace,
1544                module_to_string(&*module_));
1545
1546         // The current module node is handled specially. First, check for
1547         // its immediate children.
1548         build_reduced_graph::populate_module_if_necessary(self, &module_);
1549
1550         match module_.children.borrow().get(&name) {
1551             Some(name_bindings)
1552                     if name_bindings.defined_in_namespace(namespace) => {
1553                 debug!("top name bindings succeeded");
1554                 return Success((Target::new(module_.clone(),
1555                                             name_bindings.clone(),
1556                                             Shadowable::Never),
1557                                false));
1558             }
1559             Some(_) | None => { /* Not found; continue. */ }
1560         }
1561
1562         // Now check for its import directives. We don't have to have resolved
1563         // all its imports in the usual way; this is because chains of
1564         // adjacent import statements are processed as though they mutated the
1565         // current scope.
1566         if let Some(import_resolution) = module_.import_resolutions.borrow().get(&name) {
1567             match (*import_resolution).target_for_namespace(namespace) {
1568                 None => {
1569                     // Not found; continue.
1570                     debug!("(resolving item in lexical scope) found \
1571                             import resolution, but not in namespace {:?}",
1572                            namespace);
1573                 }
1574                 Some(target) => {
1575                     debug!("(resolving item in lexical scope) using \
1576                             import resolution");
1577                     // track used imports and extern crates as well
1578                     let id = import_resolution.id(namespace);
1579                     self.used_imports.insert((id, namespace));
1580                     self.record_import_use(id, name);
1581                     if let Some(DefId{krate: kid, ..}) = target.target_module.def_id.get() {
1582                          self.used_crates.insert(kid);
1583                     }
1584                     return Success((target, false));
1585                 }
1586             }
1587         }
1588
1589         // Search for external modules.
1590         if namespace == TypeNS {
1591             // FIXME (21114): In principle unclear `child` *has* to be lifted.
1592             let child = module_.external_module_children.borrow().get(&name).cloned();
1593             if let Some(module) = child {
1594                 let name_bindings =
1595                     Rc::new(Resolver::create_name_bindings_from_module(module));
1596                 debug!("lower name bindings succeeded");
1597                 return Success((Target::new(module_,
1598                                             name_bindings,
1599                                             Shadowable::Never),
1600                                 false));
1601             }
1602         }
1603
1604         // Finally, proceed up the scope chain looking for parent modules.
1605         let mut search_module = module_;
1606         loop {
1607             // Go to the next parent.
1608             match search_module.parent_link.clone() {
1609                 NoParentLink => {
1610                     // No more parents. This module was unresolved.
1611                     debug!("(resolving item in lexical scope) unresolved \
1612                             module");
1613                     return Failed(None);
1614                 }
1615                 ModuleParentLink(parent_module_node, _) => {
1616                     match search_module.kind.get() {
1617                         NormalModuleKind => {
1618                             // We stop the search here.
1619                             debug!("(resolving item in lexical \
1620                                     scope) unresolved module: not \
1621                                     searching through module \
1622                                     parents");
1623                             return Failed(None);
1624                         }
1625                         TraitModuleKind |
1626                         EnumModuleKind |
1627                         TypeModuleKind |
1628                         AnonymousModuleKind => {
1629                             search_module = parent_module_node.upgrade().unwrap();
1630                         }
1631                     }
1632                 }
1633                 BlockParentLink(ref parent_module_node, _) => {
1634                     search_module = parent_module_node.upgrade().unwrap();
1635                 }
1636             }
1637
1638             // Resolve the name in the parent module.
1639             match self.resolve_name_in_module(search_module.clone(),
1640                                               name,
1641                                               namespace,
1642                                               PathSearch,
1643                                               true) {
1644                 Failed(Some((span, msg))) => {
1645                     resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
1646                 },
1647                 Failed(None) => (), // Continue up the search chain.
1648                 Indeterminate => {
1649                     // We couldn't see through the higher scope because of an
1650                     // unresolved import higher up. Bail.
1651
1652                     debug!("(resolving item in lexical scope) indeterminate \
1653                             higher scope; bailing");
1654                     return Indeterminate;
1655                 }
1656                 Success((target, used_reexport)) => {
1657                     // We found the module.
1658                     debug!("(resolving item in lexical scope) found name \
1659                             in module, done");
1660                     return Success((target, used_reexport));
1661                 }
1662             }
1663         }
1664     }
1665
1666     /// Resolves a module name in the current lexical scope.
1667     fn resolve_module_in_lexical_scope(&mut self,
1668                                        module_: Rc<Module>,
1669                                        name: Name)
1670                                 -> ResolveResult<Rc<Module>> {
1671         // If this module is an anonymous module, resolve the item in the
1672         // lexical scope. Otherwise, resolve the item from the crate root.
1673         let resolve_result = self.resolve_item_in_lexical_scope(module_, name, TypeNS);
1674         match resolve_result {
1675             Success((target, _)) => {
1676                 let bindings = &*target.bindings;
1677                 match *bindings.type_def.borrow() {
1678                     Some(ref type_def) => {
1679                         match type_def.module_def {
1680                             None => {
1681                                 debug!("!!! (resolving module in lexical \
1682                                         scope) module wasn't actually a \
1683                                         module!");
1684                                 return Failed(None);
1685                             }
1686                             Some(ref module_def) => {
1687                                 return Success(module_def.clone());
1688                             }
1689                         }
1690                     }
1691                     None => {
1692                         debug!("!!! (resolving module in lexical scope) module
1693                                 wasn't actually a module!");
1694                         return Failed(None);
1695                     }
1696                 }
1697             }
1698             Indeterminate => {
1699                 debug!("(resolving module in lexical scope) indeterminate; \
1700                         bailing");
1701                 return Indeterminate;
1702             }
1703             Failed(err) => {
1704                 debug!("(resolving module in lexical scope) failed to resolve");
1705                 return Failed(err);
1706             }
1707         }
1708     }
1709
1710     /// Returns the nearest normal module parent of the given module.
1711     fn get_nearest_normal_module_parent(&mut self, module_: Rc<Module>)
1712                                             -> Option<Rc<Module>> {
1713         let mut module_ = module_;
1714         loop {
1715             match module_.parent_link.clone() {
1716                 NoParentLink => return None,
1717                 ModuleParentLink(new_module, _) |
1718                 BlockParentLink(new_module, _) => {
1719                     let new_module = new_module.upgrade().unwrap();
1720                     match new_module.kind.get() {
1721                         NormalModuleKind => return Some(new_module),
1722                         TraitModuleKind |
1723                         EnumModuleKind |
1724                         TypeModuleKind |
1725                         AnonymousModuleKind => module_ = new_module,
1726                     }
1727                 }
1728             }
1729         }
1730     }
1731
1732     /// Returns the nearest normal module parent of the given module, or the
1733     /// module itself if it is a normal module.
1734     fn get_nearest_normal_module_parent_or_self(&mut self, module_: Rc<Module>)
1735                                                 -> Rc<Module> {
1736         match module_.kind.get() {
1737             NormalModuleKind => return module_,
1738             TraitModuleKind |
1739             EnumModuleKind |
1740             TypeModuleKind |
1741             AnonymousModuleKind => {
1742                 match self.get_nearest_normal_module_parent(module_.clone()) {
1743                     None => module_,
1744                     Some(new_module) => new_module
1745                 }
1746             }
1747         }
1748     }
1749
1750     /// Resolves a "module prefix". A module prefix is one or both of (a) `self::`;
1751     /// (b) some chain of `super::`.
1752     /// grammar: (SELF MOD_SEP ) ? (SUPER MOD_SEP) *
1753     fn resolve_module_prefix(&mut self,
1754                              module_: Rc<Module>,
1755                              module_path: &[Name])
1756                                  -> ResolveResult<ModulePrefixResult> {
1757         // Start at the current module if we see `self` or `super`, or at the
1758         // top of the crate otherwise.
1759         let mut i = match &*module_path[0].as_str() {
1760             "self" => 1,
1761             "super" => 0,
1762             _ => return Success(NoPrefixFound),
1763         };
1764         let mut containing_module = self.get_nearest_normal_module_parent_or_self(module_);
1765
1766         // Now loop through all the `super`s we find.
1767         while i < module_path.len() && "super" == module_path[i].as_str() {
1768             debug!("(resolving module prefix) resolving `super` at {}",
1769                    module_to_string(&*containing_module));
1770             match self.get_nearest_normal_module_parent(containing_module) {
1771                 None => return Failed(None),
1772                 Some(new_module) => {
1773                     containing_module = new_module;
1774                     i += 1;
1775                 }
1776             }
1777         }
1778
1779         debug!("(resolving module prefix) finished resolving prefix at {}",
1780                module_to_string(&*containing_module));
1781
1782         return Success(PrefixFound(containing_module, i));
1783     }
1784
1785     /// Attempts to resolve the supplied name in the given module for the
1786     /// given namespace. If successful, returns the target corresponding to
1787     /// the name.
1788     ///
1789     /// The boolean returned on success is an indicator of whether this lookup
1790     /// passed through a public re-export proxy.
1791     fn resolve_name_in_module(&mut self,
1792                               module_: Rc<Module>,
1793                               name: Name,
1794                               namespace: Namespace,
1795                               name_search_type: NameSearchType,
1796                               allow_private_imports: bool)
1797                               -> ResolveResult<(Target, bool)> {
1798         debug!("(resolving name in module) resolving `{}` in `{}`",
1799                name,
1800                module_to_string(&*module_));
1801
1802         // First, check the direct children of the module.
1803         build_reduced_graph::populate_module_if_necessary(self, &module_);
1804
1805         match module_.children.borrow().get(&name) {
1806             Some(name_bindings)
1807                     if name_bindings.defined_in_namespace(namespace) => {
1808                 debug!("(resolving name in module) found node as child");
1809                 return Success((Target::new(module_.clone(),
1810                                             name_bindings.clone(),
1811                                             Shadowable::Never),
1812                                false));
1813             }
1814             Some(_) | None => {
1815                 // Continue.
1816             }
1817         }
1818
1819         // Next, check the module's imports if necessary.
1820
1821         // If this is a search of all imports, we should be done with glob
1822         // resolution at this point.
1823         if name_search_type == PathSearch {
1824             assert_eq!(module_.glob_count.get(), 0);
1825         }
1826
1827         // Check the list of resolved imports.
1828         match module_.import_resolutions.borrow().get(&name) {
1829             Some(import_resolution) if allow_private_imports ||
1830                                        import_resolution.is_public => {
1831
1832                 if import_resolution.is_public &&
1833                         import_resolution.outstanding_references != 0 {
1834                     debug!("(resolving name in module) import \
1835                            unresolved; bailing out");
1836                     return Indeterminate;
1837                 }
1838                 match import_resolution.target_for_namespace(namespace) {
1839                     None => {
1840                         debug!("(resolving name in module) name found, \
1841                                 but not in namespace {:?}",
1842                                namespace);
1843                     }
1844                     Some(target) => {
1845                         debug!("(resolving name in module) resolved to \
1846                                 import");
1847                         // track used imports and extern crates as well
1848                         let id = import_resolution.id(namespace);
1849                         self.used_imports.insert((id, namespace));
1850                         self.record_import_use(id, name);
1851                         if let Some(DefId{krate: kid, ..}) = target.target_module.def_id.get() {
1852                             self.used_crates.insert(kid);
1853                         }
1854                         return Success((target, true));
1855                     }
1856                 }
1857             }
1858             Some(..) | None => {} // Continue.
1859         }
1860
1861         // Finally, search through external children.
1862         if namespace == TypeNS {
1863             // FIXME (21114): In principle unclear `child` *has* to be lifted.
1864             let child = module_.external_module_children.borrow().get(&name).cloned();
1865             if let Some(module) = child {
1866                 let name_bindings =
1867                     Rc::new(Resolver::create_name_bindings_from_module(module));
1868                 return Success((Target::new(module_,
1869                                             name_bindings,
1870                                             Shadowable::Never),
1871                                 false));
1872             }
1873         }
1874
1875         // We're out of luck.
1876         debug!("(resolving name in module) failed to resolve `{}`",
1877                name);
1878         return Failed(None);
1879     }
1880
1881     fn report_unresolved_imports(&mut self, module_: Rc<Module>) {
1882         let index = module_.resolved_import_count.get();
1883         let imports = module_.imports.borrow();
1884         let import_count = imports.len();
1885         if index != import_count {
1886             resolve_error(self,
1887                           (*imports)[index].span,
1888                           ResolutionError::UnresolvedImport(None));
1889         }
1890
1891         // Descend into children and anonymous children.
1892         build_reduced_graph::populate_module_if_necessary(self, &module_);
1893
1894         for (_, child_node) in module_.children.borrow().iter() {
1895             match child_node.get_module_if_available() {
1896                 None => {
1897                     // Continue.
1898                 }
1899                 Some(child_module) => {
1900                     self.report_unresolved_imports(child_module);
1901                 }
1902             }
1903         }
1904
1905         for (_, module_) in module_.anonymous_children.borrow().iter() {
1906             self.report_unresolved_imports(module_.clone());
1907         }
1908     }
1909
1910     // AST resolution
1911     //
1912     // We maintain a list of value ribs and type ribs.
1913     //
1914     // Simultaneously, we keep track of the current position in the module
1915     // graph in the `current_module` pointer. When we go to resolve a name in
1916     // the value or type namespaces, we first look through all the ribs and
1917     // then query the module graph. When we resolve a name in the module
1918     // namespace, we can skip all the ribs (since nested modules are not
1919     // allowed within blocks in Rust) and jump straight to the current module
1920     // graph node.
1921     //
1922     // Named implementations are handled separately. When we find a method
1923     // call, we consult the module node to find all of the implementations in
1924     // scope. This information is lazily cached in the module node. We then
1925     // generate a fake "implementation scope" containing all the
1926     // implementations thus found, for compatibility with old resolve pass.
1927
1928     fn with_scope<F>(&mut self, name: Option<Name>, f: F) where
1929         F: FnOnce(&mut Resolver),
1930     {
1931         let orig_module = self.current_module.clone();
1932
1933         // Move down in the graph.
1934         match name {
1935             None => {
1936                 // Nothing to do.
1937             }
1938             Some(name) => {
1939                 build_reduced_graph::populate_module_if_necessary(self, &orig_module);
1940
1941                 match orig_module.children.borrow().get(&name) {
1942                     None => {
1943                         debug!("!!! (with scope) didn't find `{}` in `{}`",
1944                                name,
1945                                module_to_string(&*orig_module));
1946                     }
1947                     Some(name_bindings) => {
1948                         match (*name_bindings).get_module_if_available() {
1949                             None => {
1950                                 debug!("!!! (with scope) didn't find module \
1951                                         for `{}` in `{}`",
1952                                        name,
1953                                        module_to_string(&*orig_module));
1954                             }
1955                             Some(module_) => {
1956                                 self.current_module = module_;
1957                             }
1958                         }
1959                     }
1960                 }
1961             }
1962         }
1963
1964         f(self);
1965
1966         self.current_module = orig_module;
1967     }
1968
1969     /// Wraps the given definition in the appropriate number of `DefUpvar`
1970     /// wrappers.
1971     fn upvarify(&self,
1972                 ribs: &[Rib],
1973                 def_like: DefLike,
1974                 span: Span)
1975                 -> Option<DefLike> {
1976         let mut def = match def_like {
1977             DlDef(def) => def,
1978             _ => return Some(def_like)
1979         };
1980         match def {
1981             DefUpvar(..) => {
1982                 self.session.span_bug(span,
1983                     &format!("unexpected {:?} in bindings", def))
1984             }
1985             DefLocal(_, node_id) => {
1986                 for rib in ribs {
1987                     match rib.kind {
1988                         NormalRibKind => {
1989                             // Nothing to do. Continue.
1990                         }
1991                         ClosureRibKind(function_id) => {
1992                             let prev_def = def;
1993                             let node_def_id = self.ast_map.local_def_id(node_id);
1994
1995                             let mut seen = self.freevars_seen.borrow_mut();
1996                             let seen = seen.entry(function_id).or_insert_with(|| NodeMap());
1997                             if let Some(&index) = seen.get(&node_id) {
1998                                 def = DefUpvar(node_def_id, node_id, index, function_id);
1999                                 continue;
2000                             }
2001                             let mut freevars = self.freevars.borrow_mut();
2002                             let vec = freevars.entry(function_id)
2003                                               .or_insert_with(|| vec![]);
2004                             let depth = vec.len();
2005                             vec.push(Freevar { def: prev_def, span: span });
2006
2007                             def = DefUpvar(node_def_id, node_id, depth, function_id);
2008                             seen.insert(node_id, depth);
2009                         }
2010                         ItemRibKind | MethodRibKind => {
2011                             // This was an attempt to access an upvar inside a
2012                             // named function item. This is not allowed, so we
2013                             // report an error.
2014                             resolve_error(
2015                                 self,
2016                                 span,
2017                                 ResolutionError::CannotCaptureDynamicEnvironmentInFnItem
2018                             );
2019                             return None;
2020                         }
2021                         ConstantItemRibKind => {
2022                             // Still doesn't deal with upvars
2023                             resolve_error(
2024                                 self,
2025                                 span,
2026                                 ResolutionError::AttemptToUseNonConstantValueInConstant
2027                             );
2028                             return None;
2029                         }
2030                     }
2031                 }
2032             }
2033             DefTyParam(..) | DefSelfTy(..) => {
2034                 for rib in ribs {
2035                     match rib.kind {
2036                         NormalRibKind | MethodRibKind | ClosureRibKind(..) => {
2037                             // Nothing to do. Continue.
2038                         }
2039                         ItemRibKind => {
2040                             // This was an attempt to use a type parameter outside
2041                             // its scope.
2042
2043                             resolve_error(self,
2044                                           span,
2045                                           ResolutionError::TypeParametersFromOuterFunction);
2046                             return None;
2047                         }
2048                         ConstantItemRibKind => {
2049                             // see #9186
2050                             resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
2051                             return None;
2052                         }
2053                     }
2054                 }
2055             }
2056             _ => {}
2057         }
2058         Some(DlDef(def))
2059     }
2060
2061     /// Searches the current set of local scopes and
2062     /// applies translations for closures.
2063     fn search_ribs(&self,
2064                    ribs: &[Rib],
2065                    name: Name,
2066                    span: Span)
2067                    -> Option<DefLike> {
2068         // FIXME #4950: Try caching?
2069
2070         for (i, rib) in ribs.iter().enumerate().rev() {
2071             if let Some(def_like) = rib.bindings.get(&name).cloned() {
2072                 return self.upvarify(&ribs[i + 1..], def_like, span);
2073             }
2074         }
2075
2076         None
2077     }
2078
2079     /// Searches the current set of local scopes for labels.
2080     /// Stops after meeting a closure.
2081     fn search_label(&self, name: Name) -> Option<DefLike> {
2082         for rib in self.label_ribs.iter().rev() {
2083             match rib.kind {
2084                 NormalRibKind => {
2085                     // Continue
2086                 }
2087                 _ => {
2088                     // Do not resolve labels across function boundary
2089                     return None
2090                 }
2091             }
2092             let result = rib.bindings.get(&name).cloned();
2093             if result.is_some() {
2094                 return result
2095             }
2096         }
2097         None
2098     }
2099
2100     fn resolve_crate(&mut self, krate: &hir::Crate) {
2101         debug!("(resolving crate) starting");
2102
2103         visit::walk_crate(self, krate);
2104     }
2105
2106     fn check_if_primitive_type_name(&self, name: Name, span: Span) {
2107         if let Some(_) = self.primitive_type_table.primitive_types.get(&name) {
2108             span_err!(self.session, span, E0317,
2109                 "user-defined types or type parameters cannot shadow the primitive types");
2110         }
2111     }
2112
2113     fn resolve_item(&mut self, item: &Item) {
2114         let name = item.name;
2115
2116         debug!("(resolving item) resolving {}",
2117                name);
2118
2119         match item.node {
2120             ItemEnum(_, ref generics) |
2121             ItemTy(_, ref generics) |
2122             ItemStruct(_, ref generics) => {
2123                 self.check_if_primitive_type_name(name, item.span);
2124
2125                 self.with_type_parameter_rib(HasTypeParameters(generics,
2126                                                                TypeSpace,
2127                                                                ItemRibKind),
2128                                              |this| visit::walk_item(this, item));
2129             }
2130             ItemFn(_, _, _, _, ref generics, _) => {
2131                 self.with_type_parameter_rib(HasTypeParameters(generics,
2132                                                                FnSpace,
2133                                                                ItemRibKind),
2134                                              |this| visit::walk_item(this, item));
2135             }
2136
2137             ItemDefaultImpl(_, ref trait_ref) => {
2138                 self.with_optional_trait_ref(Some(trait_ref), |_, _| {});
2139             }
2140             ItemImpl(_,
2141                      _,
2142                      ref generics,
2143                      ref opt_trait_ref,
2144                      ref self_type,
2145                      ref impl_items) => {
2146                 self.resolve_implementation(generics,
2147                                             opt_trait_ref,
2148                                             &**self_type,
2149                                             item.id,
2150                                             &impl_items[..]);
2151             }
2152
2153             ItemTrait(_, ref generics, ref bounds, ref trait_items) => {
2154                 self.check_if_primitive_type_name(name, item.span);
2155
2156                 // Create a new rib for the trait-wide type parameters.
2157                 self.with_type_parameter_rib(HasTypeParameters(generics,
2158                                                                TypeSpace,
2159                                                                ItemRibKind),
2160                                              |this| {
2161                     let local_def_id = this.ast_map.local_def_id(item.id);
2162                     this.with_self_rib(DefSelfTy(Some(local_def_id), None), |this| {
2163                         this.visit_generics(generics);
2164                         walk_list!(this, visit_ty_param_bound, bounds);
2165
2166                         for trait_item in trait_items {
2167                             match trait_item.node {
2168                                 hir::ConstTraitItem(_, ref default) => {
2169                                     // Only impose the restrictions of
2170                                     // ConstRibKind if there's an actual constant
2171                                     // expression in a provided default.
2172                                     if default.is_some() {
2173                                         this.with_constant_rib(|this| {
2174                                             visit::walk_trait_item(this, trait_item)
2175                                         });
2176                                     } else {
2177                                         visit::walk_trait_item(this, trait_item)
2178                                     }
2179                                 }
2180                                 hir::MethodTraitItem(ref sig, _) => {
2181                                     let type_parameters =
2182                                         HasTypeParameters(&sig.generics,
2183                                                           FnSpace,
2184                                                           MethodRibKind);
2185                                     this.with_type_parameter_rib(type_parameters, |this| {
2186                                         visit::walk_trait_item(this, trait_item)
2187                                     });
2188                                 }
2189                                 hir::TypeTraitItem(..) => {
2190                                     this.check_if_primitive_type_name(trait_item.name,
2191                                                                       trait_item.span);
2192                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
2193                                         visit::walk_trait_item(this, trait_item)
2194                                     });
2195                                 }
2196                             };
2197                         }
2198                     });
2199                 });
2200             }
2201
2202             ItemMod(_) | ItemForeignMod(_) => {
2203                 self.with_scope(Some(name), |this| {
2204                     visit::walk_item(this, item);
2205                 });
2206             }
2207
2208             ItemConst(..) | ItemStatic(..) => {
2209                 self.with_constant_rib(|this| {
2210                     visit::walk_item(this, item);
2211                 });
2212             }
2213
2214             ItemUse(ref view_path) => {
2215                 // check for imports shadowing primitive types
2216                 let check_rename = |this: &Self, id, name| {
2217                     match this.def_map.borrow().get(&id).map(|d| d.full_def()) {
2218                         Some(DefTy(..)) | Some(DefStruct(..)) | Some(DefTrait(..)) | None => {
2219                             this.check_if_primitive_type_name(name, item.span);
2220                         }
2221                         _ => {}
2222                     }
2223                 };
2224
2225                 match view_path.node {
2226                     hir::ViewPathSimple(name, _) => {
2227                         check_rename(self, item.id, name);
2228                     }
2229                     hir::ViewPathList(ref prefix, ref items) => {
2230                         for item in items {
2231                             if let Some(name) = item.node.rename() {
2232                                 check_rename(self, item.node.id(), name);
2233                             }
2234                         }
2235
2236                         // Resolve prefix of an import with empty braces (issue #28388)
2237                         if items.is_empty() && !prefix.segments.is_empty() {
2238                             match self.resolve_crate_relative_path(prefix.span,
2239                                                                    &prefix.segments,
2240                                                                    TypeNS) {
2241                                 Some((def, lp)) => self.record_def(item.id,
2242                                                    PathResolution::new(def, lp, 0)),
2243                                 None => {
2244                                     resolve_error(self,
2245                                                   prefix.span,
2246                                                   ResolutionError::FailedToResolve(
2247                                                       &path_names_to_string(prefix, 0)));
2248                                 }
2249                             }
2250                         }
2251                     }
2252                     _ => {}
2253                 }
2254             }
2255
2256             ItemExternCrate(_) => {
2257                 // do nothing, these are just around to be encoded
2258             }
2259         }
2260     }
2261
2262     fn with_type_parameter_rib<F>(&mut self, type_parameters: TypeParameters, f: F) where
2263         F: FnOnce(&mut Resolver),
2264     {
2265         match type_parameters {
2266             HasTypeParameters(generics, space, rib_kind) => {
2267                 let mut function_type_rib = Rib::new(rib_kind);
2268                 let mut seen_bindings = HashSet::new();
2269                 for (index, type_parameter) in generics.ty_params.iter().enumerate() {
2270                     let name = type_parameter.name;
2271                     debug!("with_type_parameter_rib: {}", type_parameter.id);
2272
2273                     if seen_bindings.contains(&name) {
2274                         resolve_error(self,
2275                                       type_parameter.span,
2276                                       ResolutionError::NameAlreadyUsedInTypeParameterList(
2277                                         name)
2278                         );
2279                     }
2280                     seen_bindings.insert(name);
2281
2282                     // plain insert (no renaming)
2283                     function_type_rib.bindings.insert(name,
2284                         DlDef(DefTyParam(space,
2285                                          index as u32,
2286                                          self.ast_map.local_def_id(type_parameter.id),
2287                                          name)));
2288                 }
2289                 self.type_ribs.push(function_type_rib);
2290             }
2291
2292             NoTypeParameters => {
2293                 // Nothing to do.
2294             }
2295         }
2296
2297         f(self);
2298
2299         match type_parameters {
2300             HasTypeParameters(..) => { if !self.resolved { self.type_ribs.pop(); } }
2301             NoTypeParameters => { }
2302         }
2303     }
2304
2305     fn with_label_rib<F>(&mut self, f: F) where
2306         F: FnOnce(&mut Resolver),
2307     {
2308         self.label_ribs.push(Rib::new(NormalRibKind));
2309         f(self);
2310         if !self.resolved {
2311             self.label_ribs.pop();
2312         }
2313     }
2314
2315     fn with_constant_rib<F>(&mut self, f: F) where
2316         F: FnOnce(&mut Resolver),
2317     {
2318         self.value_ribs.push(Rib::new(ConstantItemRibKind));
2319         self.type_ribs.push(Rib::new(ConstantItemRibKind));
2320         f(self);
2321         if !self.resolved {
2322             self.type_ribs.pop();
2323             self.value_ribs.pop();
2324         }
2325     }
2326
2327     fn resolve_function(&mut self,
2328                         rib_kind: RibKind,
2329                         declaration: &FnDecl,
2330                         block: &Block) {
2331         // Create a value rib for the function.
2332         self.value_ribs.push(Rib::new(rib_kind));
2333
2334         // Create a label rib for the function.
2335         self.label_ribs.push(Rib::new(rib_kind));
2336
2337         // Add each argument to the rib.
2338         let mut bindings_list = HashMap::new();
2339         for argument in &declaration.inputs {
2340             self.resolve_pattern(&*argument.pat,
2341                                  ArgumentIrrefutableMode,
2342                                  &mut bindings_list);
2343
2344             self.visit_ty(&*argument.ty);
2345
2346             debug!("(resolving function) recorded argument");
2347         }
2348         visit::walk_fn_ret_ty(self, &declaration.output);
2349
2350         // Resolve the function body.
2351         self.visit_block(&*block);
2352
2353         debug!("(resolving function) leaving function");
2354
2355         if !self.resolved {
2356             self.label_ribs.pop();
2357             self.value_ribs.pop();
2358         }
2359     }
2360
2361     fn resolve_trait_reference(&mut self,
2362                                id: NodeId,
2363                                trait_path: &Path,
2364                                path_depth: usize)
2365                                -> Result<PathResolution, ()> {
2366         if let Some(path_res) = self.resolve_path(id, trait_path, path_depth, TypeNS, true) {
2367             if let DefTrait(_) = path_res.base_def {
2368                 debug!("(resolving trait) found trait def: {:?}", path_res);
2369                 Ok(path_res)
2370             } else {
2371                 resolve_error(self,
2372                               trait_path.span,
2373                               ResolutionError::IsNotATrait(&*path_names_to_string(trait_path,
2374                                                                                    path_depth))
2375                              );
2376
2377                 // If it's a typedef, give a note
2378                 if let DefTy(..) = path_res.base_def {
2379                     self.session.span_note(trait_path.span,
2380                                            "`type` aliases cannot be used for traits");
2381                 }
2382                 Err(())
2383             }
2384         } else {
2385             resolve_error(self,
2386                           trait_path.span,
2387                           ResolutionError::UndeclaredTraitName(
2388                             &*path_names_to_string(trait_path, path_depth))
2389                          );
2390             Err(())
2391         }
2392     }
2393
2394     fn resolve_generics(&mut self, generics: &Generics) {
2395         for type_parameter in generics.ty_params.iter() {
2396             self.check_if_primitive_type_name(type_parameter.name, type_parameter.span);
2397         }
2398         for predicate in &generics.where_clause.predicates {
2399             match predicate {
2400                 &hir::WherePredicate::BoundPredicate(_) |
2401                 &hir::WherePredicate::RegionPredicate(_) => {}
2402                 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
2403                     let path_res = self.resolve_path(eq_pred.id, &eq_pred.path, 0, TypeNS, true);
2404                     if let Some(PathResolution { base_def: DefTyParam(..), .. }) = path_res {
2405                         self.record_def(eq_pred.id, path_res.unwrap());
2406                     } else {
2407                         resolve_error(self,
2408                                       eq_pred.span,
2409                                       ResolutionError::UndeclaredAssociatedType);
2410                     }
2411                 }
2412             }
2413         }
2414         visit::walk_generics(self, generics);
2415     }
2416
2417     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
2418         where F: FnOnce(&mut Resolver) -> T
2419     {
2420         // Handle nested impls (inside fn bodies)
2421         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
2422         let result = f(self);
2423         self.current_self_type = previous_value;
2424         result
2425     }
2426
2427     fn with_optional_trait_ref<T, F>(&mut self,
2428                                      opt_trait_ref: Option<&TraitRef>,
2429                                      f: F)
2430                                      -> T
2431         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
2432     {
2433         let mut new_val = None;
2434         let mut new_id = None;
2435         if let Some(trait_ref) = opt_trait_ref {
2436             if let Ok(path_res) = self.resolve_trait_reference(trait_ref.ref_id,
2437                                                                &trait_ref.path, 0) {
2438                 assert!(path_res.depth == 0);
2439                 self.record_def(trait_ref.ref_id, path_res);
2440                 new_val = Some((path_res.base_def.def_id(), trait_ref.clone()));
2441                 new_id = Some(path_res.base_def.def_id());
2442             }
2443             visit::walk_trait_ref(self, trait_ref);
2444         }
2445         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2446         let result = f(self, new_id);
2447         self.current_trait_ref = original_trait_ref;
2448         result
2449     }
2450
2451     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
2452         where F: FnOnce(&mut Resolver)
2453     {
2454         let mut self_type_rib = Rib::new(NormalRibKind);
2455
2456         // plain insert (no renaming, types are not currently hygienic....)
2457         let name = special_names::type_self;
2458         self_type_rib.bindings.insert(name, DlDef(self_def));
2459         self.type_ribs.push(self_type_rib);
2460         f(self);
2461         if !self.resolved {
2462             self.type_ribs.pop();
2463         }
2464     }
2465
2466     fn resolve_implementation(&mut self,
2467                               generics: &Generics,
2468                               opt_trait_reference: &Option<TraitRef>,
2469                               self_type: &Ty,
2470                               item_id: NodeId,
2471                               impl_items: &[P<ImplItem>]) {
2472         // If applicable, create a rib for the type parameters.
2473         self.with_type_parameter_rib(HasTypeParameters(generics,
2474                                                        TypeSpace,
2475                                                        ItemRibKind),
2476                                      |this| {
2477             // Resolve the type parameters.
2478             this.visit_generics(generics);
2479
2480             // Resolve the trait reference, if necessary.
2481             this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2482                 // Resolve the self type.
2483                 this.visit_ty(self_type);
2484
2485                 this.with_self_rib(DefSelfTy(trait_id, Some((item_id, self_type.id))), |this| {
2486                     this.with_current_self_type(self_type, |this| {
2487                         for impl_item in impl_items {
2488                             match impl_item.node {
2489                                 ConstImplItem(..) => {
2490                                     // If this is a trait impl, ensure the const
2491                                     // exists in trait
2492                                     this.check_trait_item(impl_item.name,
2493                                                           impl_item.span,
2494                                         |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
2495                                     this.with_constant_rib(|this| {
2496                                         visit::walk_impl_item(this, impl_item);
2497                                     });
2498                                 }
2499                                 MethodImplItem(ref sig, _) => {
2500                                     // If this is a trait impl, ensure the method
2501                                     // exists in trait
2502                                     this.check_trait_item(impl_item.name,
2503                                                           impl_item.span,
2504                                         |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
2505
2506                                     // We also need a new scope for the method-
2507                                     // specific type parameters.
2508                                     let type_parameters =
2509                                         HasTypeParameters(&sig.generics,
2510                                                           FnSpace,
2511                                                           MethodRibKind);
2512                                     this.with_type_parameter_rib(type_parameters, |this| {
2513                                         visit::walk_impl_item(this, impl_item);
2514                                     });
2515                                 }
2516                                 TypeImplItem(ref ty) => {
2517                                     // If this is a trait impl, ensure the type
2518                                     // exists in trait
2519                                     this.check_trait_item(impl_item.name,
2520                                                           impl_item.span,
2521                                         |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
2522
2523                                     this.visit_ty(ty);
2524                                 }
2525                             }
2526                         }
2527                     });
2528                 });
2529             });
2530         });
2531     }
2532
2533     fn check_trait_item<F>(&self, name: Name, span: Span, err: F)
2534         where F: FnOnce(Name, &str) -> ResolutionError {
2535         // If there is a TraitRef in scope for an impl, then the method must be in the trait.
2536         if let Some((did, ref trait_ref)) = self.current_trait_ref {
2537             if !self.trait_item_map.contains_key(&(name, did)) {
2538                 let path_str = path_names_to_string(&trait_ref.path, 0);
2539                 resolve_error(self,
2540                               span,
2541                               err(name, &*path_str));
2542             }
2543         }
2544     }
2545
2546     fn resolve_local(&mut self, local: &Local) {
2547         // Resolve the type.
2548         walk_list!(self, visit_ty, &local.ty);
2549
2550         // Resolve the initializer.
2551         walk_list!(self, visit_expr, &local.init);
2552
2553         // Resolve the pattern.
2554         self.resolve_pattern(&*local.pat,
2555                              LocalIrrefutableMode,
2556                              &mut HashMap::new());
2557     }
2558
2559     // build a map from pattern identifiers to binding-info's.
2560     // this is done hygienically. This could arise for a macro
2561     // that expands into an or-pattern where one 'x' was from the
2562     // user and one 'x' came from the macro.
2563     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2564         let mut result = HashMap::new();
2565         pat_bindings_hygienic(&self.def_map, pat, |binding_mode, _id, sp, path1| {
2566             let name = mtwt::resolve(path1.node);
2567             result.insert(name, BindingInfo {
2568                 span: sp,
2569                 binding_mode: binding_mode
2570             });
2571         });
2572         return result;
2573     }
2574
2575     // check that all of the arms in an or-pattern have exactly the
2576     // same set of bindings, with the same binding modes for each.
2577     fn check_consistent_bindings(&mut self, arm: &Arm) {
2578         if arm.pats.is_empty() {
2579             return
2580         }
2581         let map_0 = self.binding_mode_map(&*arm.pats[0]);
2582         for (i, p) in arm.pats.iter().enumerate() {
2583             let map_i = self.binding_mode_map(&**p);
2584
2585             for (&key, &binding_0) in &map_0 {
2586                 match map_i.get(&key) {
2587                   None => {
2588                     resolve_error(self,
2589                                   p.span,
2590                                   ResolutionError::VariableNotBoundInPattern(key,
2591                                                                               i + 1));
2592                   }
2593                   Some(binding_i) => {
2594                     if binding_0.binding_mode != binding_i.binding_mode {
2595                         resolve_error(self,
2596                                       binding_i.span,
2597                                       ResolutionError::VariableBoundWithDifferentMode(key,
2598                                                                                        i + 1)
2599                                      );
2600                     }
2601                   }
2602                 }
2603             }
2604
2605             for (&key, &binding) in &map_i {
2606                 if !map_0.contains_key(&key) {
2607                     resolve_error(self,
2608                                   binding.span,
2609                                   ResolutionError::VariableNotBoundInParentPattern(key,
2610                                                                                     i + 1));
2611                 }
2612             }
2613         }
2614     }
2615
2616     fn resolve_arm(&mut self, arm: &Arm) {
2617         self.value_ribs.push(Rib::new(NormalRibKind));
2618
2619         let mut bindings_list = HashMap::new();
2620         for pattern in &arm.pats {
2621             self.resolve_pattern(&**pattern, RefutableMode, &mut bindings_list);
2622         }
2623
2624         // This has to happen *after* we determine which
2625         // pat_idents are variants
2626         self.check_consistent_bindings(arm);
2627
2628         walk_list!(self, visit_expr, &arm.guard);
2629         self.visit_expr(&*arm.body);
2630
2631         if !self.resolved {
2632             self.value_ribs.pop();
2633         }
2634     }
2635
2636     fn resolve_block(&mut self, block: &Block) {
2637         debug!("(resolving block) entering block");
2638         self.value_ribs.push(Rib::new(NormalRibKind));
2639
2640         // Move down in the graph, if there's an anonymous module rooted here.
2641         let orig_module = self.current_module.clone();
2642         match orig_module.anonymous_children.borrow().get(&block.id) {
2643             None => { /* Nothing to do. */ }
2644             Some(anonymous_module) => {
2645                 debug!("(resolving block) found anonymous module, moving \
2646                         down");
2647                 self.current_module = anonymous_module.clone();
2648             }
2649         }
2650
2651         // Check for imports appearing after non-item statements.
2652         let mut found_non_item = false;
2653         for statement in &block.stmts {
2654             if let hir::StmtDecl(ref declaration, _) = statement.node {
2655                 if let hir::DeclItem(ref i) = declaration.node {
2656                     match i.node {
2657                         ItemExternCrate(_) | ItemUse(_) if found_non_item => {
2658                             span_err!(self.session, i.span, E0154,
2659                                 "imports are not allowed after non-item statements");
2660                         }
2661                         _ => {}
2662                     }
2663                 } else {
2664                     found_non_item = true
2665                 }
2666             } else {
2667                 found_non_item = true;
2668             }
2669         }
2670
2671         // Descend into the block.
2672         visit::walk_block(self, block);
2673
2674         // Move back up.
2675         if !self.resolved {
2676             self.current_module = orig_module;
2677             self.value_ribs.pop();
2678         }
2679         debug!("(resolving block) leaving block");
2680     }
2681
2682     fn resolve_type(&mut self, ty: &Ty) {
2683         match ty.node {
2684             TyPath(ref maybe_qself, ref path) => {
2685                 let resolution =
2686                     match self.resolve_possibly_assoc_item(ty.id,
2687                                                            maybe_qself.as_ref(),
2688                                                            path,
2689                                                            TypeNS,
2690                                                            true) {
2691                         // `<T>::a::b::c` is resolved by typeck alone.
2692                         TypecheckRequired => {
2693                             // Resolve embedded types.
2694                             visit::walk_ty(self, ty);
2695                             return;
2696                         }
2697                         ResolveAttempt(resolution) => resolution,
2698                     };
2699
2700                 // This is a path in the type namespace. Walk through scopes
2701                 // looking for it.
2702                 match resolution {
2703                     Some(def) => {
2704                         // Write the result into the def map.
2705                         debug!("(resolving type) writing resolution for `{}` \
2706                                 (id {}) = {:?}",
2707                                path_names_to_string(path, 0),
2708                                ty.id, def);
2709                         self.record_def(ty.id, def);
2710                     }
2711                     None => {
2712                         // Keep reporting some errors even if they're ignored above.
2713                         self.resolve_path(ty.id, path, 0, TypeNS, true);
2714
2715                         let kind = if maybe_qself.is_some() {
2716                             "associated type"
2717                         } else {
2718                             "type name"
2719                         };
2720
2721                         let self_type_name = special_idents::type_self.name;
2722                         let is_invalid_self_type_name =
2723                             path.segments.len() > 0 &&
2724                             maybe_qself.is_none() &&
2725                             path.segments[0].identifier.name == self_type_name;
2726                         if is_invalid_self_type_name {
2727                             resolve_error(self,
2728                                           ty.span,
2729                                           ResolutionError::SelfUsedOutsideImplOrTrait);
2730                         } else {
2731                             resolve_error(self,
2732                                           ty.span,
2733                                           ResolutionError::UseOfUndeclared(
2734                                                                     kind,
2735                                                                     &*path_names_to_string(path,
2736                                                                                            0))
2737                                          );
2738                         }
2739                     }
2740                 }
2741             }
2742             _ => {}
2743         }
2744         // Resolve embedded types.
2745         visit::walk_ty(self, ty);
2746     }
2747
2748     fn resolve_pattern(&mut self,
2749                        pattern: &Pat,
2750                        mode: PatternBindingMode,
2751                        // Maps idents to the node ID for the (outermost)
2752                        // pattern that binds them
2753                        bindings_list: &mut HashMap<Name, NodeId>) {
2754         let pat_id = pattern.id;
2755         walk_pat(pattern, |pattern| {
2756             match pattern.node {
2757                 PatIdent(binding_mode, ref path1, ref at_rhs) => {
2758                     // The meaning of PatIdent with no type parameters
2759                     // depends on whether an enum variant or unit-like struct
2760                     // with that name is in scope. The probing lookup has to
2761                     // be careful not to emit spurious errors. Only matching
2762                     // patterns (match) can match nullary variants or
2763                     // unit-like structs. For binding patterns (let
2764                     // and the LHS of @-patterns), matching such a value is
2765                     // simply disallowed (since it's rarely what you want).
2766                     let const_ok = mode == RefutableMode && at_rhs.is_none();
2767
2768                     let ident = path1.node;
2769                     let renamed = mtwt::resolve(ident);
2770
2771                     match self.resolve_bare_identifier_pattern(ident.name, pattern.span) {
2772                         FoundStructOrEnumVariant(def, lp) if const_ok => {
2773                             debug!("(resolving pattern) resolving `{}` to \
2774                                     struct or enum variant",
2775                                    renamed);
2776
2777                             self.enforce_default_binding_mode(
2778                                 pattern,
2779                                 binding_mode,
2780                                 "an enum variant");
2781                             self.record_def(pattern.id, PathResolution {
2782                                 base_def: def,
2783                                 last_private: lp,
2784                                 depth: 0
2785                             });
2786                         }
2787                         FoundStructOrEnumVariant(..) => {
2788                             resolve_error(
2789                                 self,
2790                                 pattern.span,
2791                                 ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(
2792                                     renamed)
2793                             );
2794                         }
2795                         FoundConst(def, lp) if const_ok => {
2796                             debug!("(resolving pattern) resolving `{}` to \
2797                                     constant",
2798                                    renamed);
2799
2800                             self.enforce_default_binding_mode(
2801                                 pattern,
2802                                 binding_mode,
2803                                 "a constant");
2804                             self.record_def(pattern.id, PathResolution {
2805                                 base_def: def,
2806                                 last_private: lp,
2807                                 depth: 0
2808                             });
2809                         }
2810                         FoundConst(..) => {
2811                             resolve_error(
2812                                 self,
2813                                 pattern.span,
2814                                 ResolutionError::OnlyIrrefutablePatternsAllowedHere
2815                             );
2816                         }
2817                         BareIdentifierPatternUnresolved => {
2818                             debug!("(resolving pattern) binding `{}`",
2819                                    renamed);
2820
2821                             let def_id = self.ast_map.local_def_id(pattern.id);
2822                             let def = DefLocal(def_id, pattern.id);
2823
2824                             // Record the definition so that later passes
2825                             // will be able to distinguish variants from
2826                             // locals in patterns.
2827
2828                             self.record_def(pattern.id, PathResolution {
2829                                 base_def: def,
2830                                 last_private: LastMod(AllPublic),
2831                                 depth: 0
2832                             });
2833
2834                             // Add the binding to the local ribs, if it
2835                             // doesn't already exist in the bindings list. (We
2836                             // must not add it if it's in the bindings list
2837                             // because that breaks the assumptions later
2838                             // passes make about or-patterns.)
2839                             if !bindings_list.contains_key(&renamed) {
2840                                 let this = &mut *self;
2841                                 let last_rib = this.value_ribs.last_mut().unwrap();
2842                                 last_rib.bindings.insert(renamed, DlDef(def));
2843                                 bindings_list.insert(renamed, pat_id);
2844                             } else if mode == ArgumentIrrefutableMode &&
2845                                     bindings_list.contains_key(&renamed) {
2846                                 // Forbid duplicate bindings in the same
2847                                 // parameter list.
2848                                 resolve_error(
2849                                     self,
2850                                     pattern.span,
2851                                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2852                                         &ident.name.as_str())
2853                                 );
2854                             } else if bindings_list.get(&renamed) ==
2855                                     Some(&pat_id) {
2856                                 // Then this is a duplicate variable in the
2857                                 // same disjunction, which is an error.
2858                                 resolve_error(
2859                                     self,
2860                                     pattern.span,
2861                                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2862                                         &ident.name.as_str())
2863                                 );
2864                             }
2865                             // Else, not bound in the same pattern: do
2866                             // nothing.
2867                         }
2868                     }
2869                 }
2870
2871                 PatEnum(ref path, _) => {
2872                     // This must be an enum variant, struct or const.
2873                     let resolution =
2874                         match self.resolve_possibly_assoc_item(pat_id, None,
2875                                                                path, ValueNS,
2876                                                                false) {
2877                             // The below shouldn't happen because all
2878                             // qualified paths should be in PatQPath.
2879                             TypecheckRequired =>
2880                                 self.session.span_bug(
2881                                     path.span,
2882                                     "resolve_possibly_assoc_item claimed
2883                                      that a path in PatEnum requires typecheck
2884                                      to resolve, but qualified paths should be
2885                                      PatQPath"),
2886                             ResolveAttempt(resolution) => resolution,
2887                         };
2888                     if let Some(path_res) = resolution {
2889                         match path_res.base_def {
2890                             DefVariant(..) | DefStruct(..) | DefConst(..) => {
2891                                 self.record_def(pattern.id, path_res);
2892                             }
2893                             DefStatic(..) => {
2894                                 resolve_error(&self,
2895                                               path.span,
2896                                               ResolutionError::StaticVariableReference);
2897                             }
2898                             _ => {
2899                                 // If anything ends up here entirely resolved,
2900                                 // it's an error. If anything ends up here
2901                                 // partially resolved, that's OK, because it may
2902                                 // be a `T::CONST` that typeck will resolve.
2903                                 if path_res.depth == 0 {
2904                                     resolve_error(
2905                                         self,
2906                                         path.span,
2907                                         ResolutionError::NotAnEnumVariantStructOrConst(
2908                                             &path.segments
2909                                                  .last()
2910                                                  .unwrap()
2911                                                  .identifier
2912                                                  .name
2913                                                  .as_str())
2914                                     );
2915                                 } else {
2916                                     let const_name = path.segments.last().unwrap()
2917                                                          .identifier.name;
2918                                     let traits = self.get_traits_containing_item(const_name);
2919                                     self.trait_map.insert(pattern.id, traits);
2920                                     self.record_def(pattern.id, path_res);
2921                                 }
2922                             }
2923                         }
2924                     } else {
2925                         resolve_error(
2926                             self,
2927                             path.span,
2928                             ResolutionError::UnresolvedEnumVariantStructOrConst(
2929                                 &path.segments.last().unwrap().identifier.name.as_str())
2930                         );
2931                     }
2932                     visit::walk_path(self, path);
2933                 }
2934
2935                 PatQPath(ref qself, ref path) => {
2936                     // Associated constants only.
2937                     let resolution =
2938                         match self.resolve_possibly_assoc_item(pat_id, Some(qself),
2939                                                                path, ValueNS,
2940                                                                false) {
2941                             TypecheckRequired => {
2942                                 // All `<T>::CONST` should end up here, and will
2943                                 // require use of the trait map to resolve
2944                                 // during typechecking.
2945                                 let const_name = path.segments.last().unwrap()
2946                                                      .identifier.name;
2947                                 let traits = self.get_traits_containing_item(const_name);
2948                                 self.trait_map.insert(pattern.id, traits);
2949                                 visit::walk_pat(self, pattern);
2950                                 return true;
2951                             }
2952                             ResolveAttempt(resolution) => resolution,
2953                         };
2954                     if let Some(path_res) = resolution {
2955                         match path_res.base_def {
2956                             // All `<T as Trait>::CONST` should end up here, and
2957                             // have the trait already selected.
2958                             DefAssociatedConst(..) => {
2959                                 self.record_def(pattern.id, path_res);
2960                             }
2961                             _ => {
2962                                 resolve_error(
2963                                     self,
2964                                     path.span,
2965                                     ResolutionError::NotAnAssociatedConst(
2966                                         &path.segments.last().unwrap().identifier.name.as_str()
2967                                     )
2968                                 );
2969                             }
2970                         }
2971                     } else {
2972                         resolve_error(
2973                             self,
2974                             path.span,
2975                             ResolutionError::UnresolvedAssociatedConst(
2976                                 &path.segments.last().unwrap().identifier.name.as_str()
2977                             )
2978                         );
2979                     }
2980                     visit::walk_pat(self, pattern);
2981                 }
2982
2983                 PatStruct(ref path, _, _) => {
2984                     match self.resolve_path(pat_id, path, 0, TypeNS, false) {
2985                         Some(definition) => {
2986                             self.record_def(pattern.id, definition);
2987                         }
2988                         result => {
2989                             debug!("(resolving pattern) didn't find struct \
2990                                     def: {:?}", result);
2991                             resolve_error(
2992                                 self,
2993                                 path.span,
2994                                 ResolutionError::DoesNotNameAStruct(
2995                                     &*path_names_to_string(path, 0))
2996                             );
2997                         }
2998                     }
2999                     visit::walk_path(self, path);
3000                 }
3001
3002                 PatLit(_) | PatRange(..) => {
3003                     visit::walk_pat(self, pattern);
3004                 }
3005
3006                 _ => {
3007                     // Nothing to do.
3008                 }
3009             }
3010             true
3011         });
3012     }
3013
3014     fn resolve_bare_identifier_pattern(&mut self, name: Name, span: Span)
3015                                        -> BareIdentifierPatternResolution {
3016         let module = self.current_module.clone();
3017         match self.resolve_item_in_lexical_scope(module,
3018                                                  name,
3019                                                  ValueNS) {
3020             Success((target, _)) => {
3021                 debug!("(resolve bare identifier pattern) succeeded in \
3022                          finding {} at {:?}",
3023                         name,
3024                         target.bindings.value_def.borrow());
3025                 match *target.bindings.value_def.borrow() {
3026                     None => {
3027                         panic!("resolved name in the value namespace to a \
3028                               set of name bindings with no def?!");
3029                     }
3030                     Some(def) => {
3031                         // For the two success cases, this lookup can be
3032                         // considered as not having a private component because
3033                         // the lookup happened only within the current module.
3034                         match def.def {
3035                             def @ DefVariant(..) | def @ DefStruct(..) => {
3036                                 return FoundStructOrEnumVariant(def, LastMod(AllPublic));
3037                             }
3038                             def @ DefConst(..) | def @ DefAssociatedConst(..) => {
3039                                 return FoundConst(def, LastMod(AllPublic));
3040                             }
3041                             DefStatic(..) => {
3042                                 resolve_error(self,
3043                                               span,
3044                                               ResolutionError::StaticVariableReference);
3045                                 return BareIdentifierPatternUnresolved;
3046                             }
3047                             _ => {
3048                                 return BareIdentifierPatternUnresolved;
3049                             }
3050                         }
3051                     }
3052                 }
3053             }
3054
3055             Indeterminate => {
3056                 panic!("unexpected indeterminate result");
3057             }
3058             Failed(err) => {
3059                 match err {
3060                     Some((span, msg)) => {
3061                         resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
3062                     }
3063                     None => ()
3064                 }
3065
3066                 debug!("(resolve bare identifier pattern) failed to find {}",
3067                         name);
3068                 return BareIdentifierPatternUnresolved;
3069             }
3070         }
3071     }
3072
3073     /// Handles paths that may refer to associated items
3074     fn resolve_possibly_assoc_item(&mut self,
3075                                    id: NodeId,
3076                                    maybe_qself: Option<&hir::QSelf>,
3077                                    path: &Path,
3078                                    namespace: Namespace,
3079                                    check_ribs: bool)
3080                                    -> AssocItemResolveResult
3081     {
3082         let max_assoc_types;
3083
3084         match maybe_qself {
3085             Some(qself) => {
3086                 if qself.position == 0 {
3087                     return TypecheckRequired;
3088                 }
3089                 max_assoc_types = path.segments.len() - qself.position;
3090                 // Make sure the trait is valid.
3091                 let _ = self.resolve_trait_reference(id, path, max_assoc_types);
3092             }
3093             None => {
3094                 max_assoc_types = path.segments.len();
3095             }
3096         }
3097
3098         let mut resolution = self.with_no_errors(|this| {
3099             this.resolve_path(id, path, 0, namespace, check_ribs)
3100         });
3101         for depth in 1..max_assoc_types {
3102             if resolution.is_some() {
3103                 break;
3104             }
3105             self.with_no_errors(|this| {
3106                 resolution = this.resolve_path(id, path, depth,
3107                                                TypeNS, true);
3108             });
3109         }
3110         if let Some(DefMod(_)) = resolution.map(|r| r.base_def) {
3111             // A module is not a valid type or value.
3112             resolution = None;
3113         }
3114         ResolveAttempt(resolution)
3115     }
3116
3117     /// If `check_ribs` is true, checks the local definitions first; i.e.
3118     /// doesn't skip straight to the containing module.
3119     /// Skips `path_depth` trailing segments, which is also reflected in the
3120     /// returned value. See `middle::def::PathResolution` for more info.
3121     pub fn resolve_path(&mut self,
3122                         id: NodeId,
3123                         path: &Path,
3124                         path_depth: usize,
3125                         namespace: Namespace,
3126                         check_ribs: bool) -> Option<PathResolution> {
3127         let span = path.span;
3128         let segments = &path.segments[..path.segments.len()-path_depth];
3129
3130         let mk_res = |(def, lp)| PathResolution::new(def, lp, path_depth);
3131
3132         if path.global {
3133             let def = self.resolve_crate_relative_path(span, segments, namespace);
3134             return def.map(mk_res);
3135         }
3136
3137         // Try to find a path to an item in a module.
3138         let unqualified_def =
3139                 self.resolve_identifier(segments.last().unwrap().identifier,
3140                                         namespace,
3141                                         check_ribs,
3142                                         span);
3143
3144         if segments.len() <= 1 {
3145             return unqualified_def.map(mk_res);
3146         }
3147
3148         let def = self.resolve_module_relative_path(span, segments, namespace);
3149         match (def, unqualified_def) {
3150             (Some((ref d, _)), Some((ref ud, _))) if *d == *ud => {
3151                 self.session
3152                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
3153                               id, span,
3154                               "unnecessary qualification".to_string());
3155             }
3156             _ => {}
3157         }
3158
3159         def.map(mk_res)
3160     }
3161
3162     // Resolve a single identifier.
3163     fn resolve_identifier(&mut self,
3164                           identifier: Ident,
3165                           namespace: Namespace,
3166                           check_ribs: bool,
3167                           span: Span)
3168                           -> Option<(Def, LastPrivate)> {
3169         // First, check to see whether the name is a primitive type.
3170         if namespace == TypeNS {
3171             if let Some(&prim_ty) = self.primitive_type_table
3172                                         .primitive_types
3173                                         .get(&identifier.name) {
3174                 return Some((DefPrimTy(prim_ty), LastMod(AllPublic)));
3175             }
3176         }
3177
3178         if check_ribs {
3179             if let Some(def) = self.resolve_identifier_in_local_ribs(identifier,
3180                                                                      namespace,
3181                                                                      span) {
3182                 return Some((def, LastMod(AllPublic)));
3183             }
3184         }
3185
3186         self.resolve_item_by_name_in_lexical_scope(identifier.name, namespace)
3187     }
3188
3189     // FIXME #4952: Merge me with resolve_name_in_module?
3190     fn resolve_definition_of_name_in_module(&mut self,
3191                                             containing_module: Rc<Module>,
3192                                             name: Name,
3193                                             namespace: Namespace)
3194                                             -> NameDefinition {
3195         // First, search children.
3196         build_reduced_graph::populate_module_if_necessary(self, &containing_module);
3197
3198         match containing_module.children.borrow().get(&name) {
3199             Some(child_name_bindings) => {
3200                 match child_name_bindings.def_for_namespace(namespace) {
3201                     Some(def) => {
3202                         // Found it. Stop the search here.
3203                         let p = child_name_bindings.defined_in_public_namespace(namespace);
3204                         let lp = if p {LastMod(AllPublic)} else {
3205                             LastMod(DependsOn(def.def_id()))
3206                         };
3207                         return ChildNameDefinition(def, lp);
3208                     }
3209                     None => {}
3210                 }
3211             }
3212             None => {}
3213         }
3214
3215         // Next, search import resolutions.
3216         match containing_module.import_resolutions.borrow().get(&name) {
3217             Some(import_resolution) if import_resolution.is_public => {
3218                 if let Some(target) = (*import_resolution).target_for_namespace(namespace) {
3219                     match target.bindings.def_for_namespace(namespace) {
3220                         Some(def) => {
3221                             // Found it.
3222                             let id = import_resolution.id(namespace);
3223                             // track imports and extern crates as well
3224                             self.used_imports.insert((id, namespace));
3225                             self.record_import_use(id, name);
3226                             match target.target_module.def_id.get() {
3227                                 Some(DefId{krate: kid, ..}) => {
3228                                     self.used_crates.insert(kid);
3229                                 },
3230                                 _ => {}
3231                             }
3232                             return ImportNameDefinition(def, LastMod(AllPublic));
3233                         }
3234                         None => {
3235                             // This can happen with external impls, due to
3236                             // the imperfect way we read the metadata.
3237                         }
3238                     }
3239                 }
3240             }
3241             Some(..) | None => {} // Continue.
3242         }
3243
3244         // Finally, search through external children.
3245         if namespace == TypeNS {
3246             if let Some(module) = containing_module.external_module_children.borrow()
3247                                                    .get(&name).cloned() {
3248                 if let Some(def_id) = module.def_id.get() {
3249                     // track used crates
3250                     self.used_crates.insert(def_id.krate);
3251                     let lp = if module.is_public {LastMod(AllPublic)} else {
3252                         LastMod(DependsOn(def_id))
3253                     };
3254                     return ChildNameDefinition(DefMod(def_id), lp);
3255                 }
3256             }
3257         }
3258
3259         return NoNameDefinition;
3260     }
3261
3262     // resolve a "module-relative" path, e.g. a::b::c
3263     fn resolve_module_relative_path(&mut self,
3264                                     span: Span,
3265                                     segments: &[hir::PathSegment],
3266                                     namespace: Namespace)
3267                                     -> Option<(Def, LastPrivate)> {
3268         let module_path = segments.split_last().unwrap().1.iter()
3269                                          .map(|ps| ps.identifier.name)
3270                                          .collect::<Vec<_>>();
3271
3272         let containing_module;
3273         let last_private;
3274         let current_module = self.current_module.clone();
3275         match self.resolve_module_path(current_module,
3276                                        &module_path[..],
3277                                        UseLexicalScope,
3278                                        span,
3279                                        PathSearch) {
3280             Failed(err) => {
3281                 let (span, msg) = match err {
3282                     Some((span, msg)) => (span, msg),
3283                     None => {
3284                         let msg = format!("Use of undeclared type or module `{}`",
3285                                           names_to_string(&module_path));
3286                         (span, msg)
3287                     }
3288                 };
3289
3290                 resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
3291                 return None;
3292             }
3293             Indeterminate => panic!("indeterminate unexpected"),
3294             Success((resulting_module, resulting_last_private)) => {
3295                 containing_module = resulting_module;
3296                 last_private = resulting_last_private;
3297             }
3298         }
3299
3300         let name = segments.last().unwrap().identifier.name;
3301         let def = match self.resolve_definition_of_name_in_module(containing_module.clone(),
3302                                                                   name,
3303                                                                   namespace) {
3304             NoNameDefinition => {
3305                 // We failed to resolve the name. Report an error.
3306                 return None;
3307             }
3308             ChildNameDefinition(def, lp) | ImportNameDefinition(def, lp) => {
3309                 (def, last_private.or(lp))
3310             }
3311         };
3312         if let Some(DefId{krate: kid, ..}) = containing_module.def_id.get() {
3313             self.used_crates.insert(kid);
3314         }
3315         return Some(def);
3316     }
3317
3318     /// Invariant: This must be called only during main resolution, not during
3319     /// import resolution.
3320     fn resolve_crate_relative_path(&mut self,
3321                                    span: Span,
3322                                    segments: &[hir::PathSegment],
3323                                    namespace: Namespace)
3324                                        -> Option<(Def, LastPrivate)> {
3325         let module_path = segments.split_last().unwrap().1.iter()
3326                                          .map(|ps| ps.identifier.name)
3327                                          .collect::<Vec<_>>();
3328
3329         let root_module = self.graph_root.get_module();
3330
3331         let containing_module;
3332         let last_private;
3333         match self.resolve_module_path_from_root(root_module,
3334                                                  &module_path[..],
3335                                                  0,
3336                                                  span,
3337                                                  PathSearch,
3338                                                  LastMod(AllPublic)) {
3339             Failed(err) => {
3340                 let (span, msg) = match err {
3341                     Some((span, msg)) => (span, msg),
3342                     None => {
3343                         let msg = format!("Use of undeclared module `::{}`",
3344                                           names_to_string(&module_path[..]));
3345                         (span, msg)
3346                     }
3347                 };
3348
3349                 resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
3350                 return None;
3351             }
3352
3353             Indeterminate => {
3354                 panic!("indeterminate unexpected");
3355             }
3356
3357             Success((resulting_module, resulting_last_private)) => {
3358                 containing_module = resulting_module;
3359                 last_private = resulting_last_private;
3360             }
3361         }
3362
3363         let name = segments.last().unwrap().identifier.name;
3364         match self.resolve_definition_of_name_in_module(containing_module,
3365                                                         name,
3366                                                         namespace) {
3367             NoNameDefinition => {
3368                 // We failed to resolve the name. Report an error.
3369                 return None;
3370             }
3371             ChildNameDefinition(def, lp) | ImportNameDefinition(def, lp) => {
3372                 return Some((def, last_private.or(lp)));
3373             }
3374         }
3375     }
3376
3377     fn resolve_identifier_in_local_ribs(&mut self,
3378                                         ident: Ident,
3379                                         namespace: Namespace,
3380                                         span: Span)
3381                                         -> Option<Def> {
3382         // Check the local set of ribs.
3383         let search_result = match namespace {
3384             ValueNS => {
3385                 let renamed = mtwt::resolve(ident);
3386                 self.search_ribs(&self.value_ribs, renamed, span)
3387             }
3388             TypeNS => {
3389                 let name = ident.name;
3390                 self.search_ribs(&self.type_ribs, name, span)
3391             }
3392         };
3393
3394         match search_result {
3395             Some(DlDef(def)) => {
3396                 debug!("(resolving path in local ribs) resolved `{}` to local: {:?}",
3397                        ident,
3398                        def);
3399                 Some(def)
3400             }
3401             Some(DlField) | Some(DlImpl(_)) | None => {
3402                 None
3403             }
3404         }
3405     }
3406
3407     fn resolve_item_by_name_in_lexical_scope(&mut self,
3408                                              name: Name,
3409                                              namespace: Namespace)
3410                                             -> Option<(Def, LastPrivate)> {
3411         // Check the items.
3412         let module = self.current_module.clone();
3413         match self.resolve_item_in_lexical_scope(module,
3414                                                  name,
3415                                                  namespace) {
3416             Success((target, _)) => {
3417                 match (*target.bindings).def_for_namespace(namespace) {
3418                     None => {
3419                         // This can happen if we were looking for a type and
3420                         // found a module instead. Modules don't have defs.
3421                         debug!("(resolving item path by identifier in lexical \
3422                                  scope) failed to resolve {} after success...",
3423                                  name);
3424                         return None;
3425                     }
3426                     Some(def) => {
3427                         debug!("(resolving item path in lexical scope) \
3428                                 resolved `{}` to item",
3429                                name);
3430                         // This lookup is "all public" because it only searched
3431                         // for one identifier in the current module (couldn't
3432                         // have passed through reexports or anything like that.
3433                         return Some((def, LastMod(AllPublic)));
3434                     }
3435                 }
3436             }
3437             Indeterminate => {
3438                 panic!("unexpected indeterminate result");
3439             }
3440             Failed(err) => {
3441                 debug!("(resolving item path by identifier in lexical scope) \
3442                          failed to resolve {}", name);
3443
3444                 if let Some((span, msg)) = err {
3445                     resolve_error(self, span, ResolutionError::FailedToResolve(&*msg))
3446                 }
3447
3448                 return None;
3449             }
3450         }
3451     }
3452
3453     fn with_no_errors<T, F>(&mut self, f: F) -> T where
3454         F: FnOnce(&mut Resolver) -> T,
3455     {
3456         self.emit_errors = false;
3457         let rs = f(self);
3458         self.emit_errors = true;
3459         rs
3460     }
3461
3462     fn find_fallback_in_self_type(&mut self, name: Name) -> FallbackSuggestion {
3463         fn extract_path_and_node_id(t: &Ty, allow: FallbackChecks)
3464                                                     -> Option<(Path, NodeId, FallbackChecks)> {
3465             match t.node {
3466                 TyPath(None, ref path) => Some((path.clone(), t.id, allow)),
3467                 TyPtr(ref mut_ty) => extract_path_and_node_id(&*mut_ty.ty, OnlyTraitAndStatics),
3468                 TyRptr(_, ref mut_ty) => extract_path_and_node_id(&*mut_ty.ty, allow),
3469                 // This doesn't handle the remaining `Ty` variants as they are not
3470                 // that commonly the self_type, it might be interesting to provide
3471                 // support for those in future.
3472                 _ => None,
3473             }
3474         }
3475
3476         fn get_module(this: &mut Resolver, span: Span, name_path: &[ast::Name])
3477                             -> Option<Rc<Module>> {
3478             let root = this.current_module.clone();
3479             let last_name = name_path.last().unwrap();
3480
3481             if name_path.len() == 1 {
3482                 match this.primitive_type_table.primitive_types.get(last_name) {
3483                     Some(_) => None,
3484                     None => {
3485                         match this.current_module.children.borrow().get(last_name) {
3486                             Some(child) => child.get_module_if_available(),
3487                             None => None
3488                         }
3489                     }
3490                 }
3491             } else {
3492                 match this.resolve_module_path(root,
3493                                                &name_path[..],
3494                                                UseLexicalScope,
3495                                                span,
3496                                                PathSearch) {
3497                     Success((module, _)) => Some(module),
3498                     _ => None
3499                 }
3500             }
3501         }
3502
3503         fn is_static_method(this: &Resolver, did: DefId) -> bool {
3504             if let Some(node_id) = this.ast_map.as_local_node_id(did) {
3505                 let sig = match this.ast_map.get(node_id) {
3506                     hir_map::NodeTraitItem(trait_item) => match trait_item.node {
3507                         hir::MethodTraitItem(ref sig, _) => sig,
3508                         _ => return false
3509                     },
3510                     hir_map::NodeImplItem(impl_item) => match impl_item.node {
3511                         hir::MethodImplItem(ref sig, _) => sig,
3512                         _ => return false
3513                     },
3514                     _ => return false
3515                 };
3516                 sig.explicit_self.node == hir::SelfStatic
3517             } else {
3518                 csearch::is_static_method(&this.session.cstore, did)
3519             }
3520         }
3521
3522         let (path, node_id, allowed) = match self.current_self_type {
3523             Some(ref ty) => match extract_path_and_node_id(ty, Everything) {
3524                 Some(x) => x,
3525                 None => return NoSuggestion,
3526             },
3527             None => return NoSuggestion,
3528         };
3529
3530         if allowed == Everything {
3531             // Look for a field with the same name in the current self_type.
3532             match self.def_map.borrow().get(&node_id).map(|d| d.full_def()) {
3533                 Some(DefTy(did, _)) |
3534                 Some(DefStruct(did)) |
3535                 Some(DefVariant(_, did, _)) => match self.structs.get(&did) {
3536                     None => {}
3537                     Some(fields) => {
3538                         if fields.iter().any(|&field_name| name == field_name) {
3539                             return Field;
3540                         }
3541                     }
3542                 },
3543                 _ => {} // Self type didn't resolve properly
3544             }
3545         }
3546
3547         let name_path = path.segments.iter().map(|seg| seg.identifier.name).collect::<Vec<_>>();
3548
3549         // Look for a method in the current self type's impl module.
3550         if let Some(module) = get_module(self, path.span, &name_path) {
3551             if let Some(binding) = module.children.borrow().get(&name) {
3552                 if let Some(DefMethod(did)) = binding.def_for_namespace(ValueNS) {
3553                     if is_static_method(self, did) {
3554                         return StaticMethod(path_names_to_string(&path, 0))
3555                     }
3556                     if self.current_trait_ref.is_some() {
3557                         return TraitItem;
3558                     } else if allowed == Everything {
3559                         return Method;
3560                     }
3561                 }
3562             }
3563         }
3564
3565         // Look for a method in the current trait.
3566         if let Some((trait_did, ref trait_ref)) = self.current_trait_ref {
3567             if let Some(&did) = self.trait_item_map.get(&(name, trait_did)) {
3568                 if is_static_method(self, did) {
3569                     return TraitMethod(path_names_to_string(&trait_ref.path, 0));
3570                 } else {
3571                     return TraitItem;
3572                 }
3573             }
3574         }
3575
3576         NoSuggestion
3577     }
3578
3579     fn find_best_match_for_name(&mut self, name: &str) -> Option<String> {
3580         let mut maybes: Vec<token::InternedString> = Vec::new();
3581         let mut values: Vec<usize> = Vec::new();
3582
3583         for rib in self.value_ribs.iter().rev() {
3584             for (&k, _) in &rib.bindings {
3585                 maybes.push(k.as_str());
3586                 values.push(usize::MAX);
3587             }
3588         }
3589
3590         let mut smallest = 0;
3591         for (i, other) in maybes.iter().enumerate() {
3592             values[i] = lev_distance(name, &other);
3593
3594             if values[i] <= values[smallest] {
3595                 smallest = i;
3596             }
3597         }
3598
3599         // As a loose rule to avoid obviously incorrect suggestions, clamp the
3600         // maximum edit distance we will accept for a suggestion to one third of
3601         // the typo'd name's length.
3602         let max_distance = std::cmp::max(name.len(), 3) / 3;
3603
3604         if !values.is_empty() &&
3605             values[smallest] <= max_distance &&
3606             name != &maybes[smallest][..] {
3607
3608             Some(maybes[smallest].to_string())
3609
3610         } else {
3611             None
3612         }
3613     }
3614
3615     fn resolve_expr(&mut self, expr: &Expr) {
3616         // First, record candidate traits for this expression if it could
3617         // result in the invocation of a method call.
3618
3619         self.record_candidate_traits_for_expr_if_necessary(expr);
3620
3621         // Next, resolve the node.
3622         match expr.node {
3623             ExprPath(ref maybe_qself, ref path) => {
3624                 let resolution =
3625                     match self.resolve_possibly_assoc_item(expr.id,
3626                                                            maybe_qself.as_ref(),
3627                                                            path,
3628                                                            ValueNS,
3629                                                            true) {
3630                         // `<T>::a::b::c` is resolved by typeck alone.
3631                         TypecheckRequired => {
3632                             let method_name = path.segments.last().unwrap().identifier.name;
3633                             let traits = self.get_traits_containing_item(method_name);
3634                             self.trait_map.insert(expr.id, traits);
3635                             visit::walk_expr(self, expr);
3636                             return;
3637                         }
3638                         ResolveAttempt(resolution) => resolution,
3639                     };
3640
3641                 // This is a local path in the value namespace. Walk through
3642                 // scopes looking for it.
3643                 if let Some(path_res) = resolution {
3644                     // Check if struct variant
3645                     if let DefVariant(_, _, true) = path_res.base_def {
3646                         let path_name = path_names_to_string(path, 0);
3647
3648                         resolve_error(self,
3649                                       expr.span,
3650                                       ResolutionError::StructVariantUsedAsFunction(&*path_name));
3651
3652                         let msg = format!("did you mean to write: \
3653                                            `{} {{ /* fields */ }}`?",
3654                                           path_name);
3655                         if self.emit_errors {
3656                             self.session.fileline_help(expr.span, &msg);
3657                         } else {
3658                             self.session.span_help(expr.span, &msg);
3659                         }
3660                     } else {
3661                         // Write the result into the def map.
3662                         debug!("(resolving expr) resolved `{}`",
3663                                path_names_to_string(path, 0));
3664
3665                         // Partial resolutions will need the set of traits in scope,
3666                         // so they can be completed during typeck.
3667                         if path_res.depth != 0 {
3668                             let method_name = path.segments.last().unwrap().identifier.name;
3669                             let traits = self.get_traits_containing_item(method_name);
3670                             self.trait_map.insert(expr.id, traits);
3671                         }
3672
3673                         self.record_def(expr.id, path_res);
3674                     }
3675                 } else {
3676                     // Be helpful if the name refers to a struct
3677                     // (The pattern matching def_tys where the id is in self.structs
3678                     // matches on regular structs while excluding tuple- and enum-like
3679                     // structs, which wouldn't result in this error.)
3680                     let path_name = path_names_to_string(path, 0);
3681                     let type_res = self.with_no_errors(|this| {
3682                         this.resolve_path(expr.id, path, 0, TypeNS, false)
3683                     });
3684                     match type_res.map(|r| r.base_def) {
3685                         Some(DefTy(struct_id, _))
3686                             if self.structs.contains_key(&struct_id) => {
3687                                 resolve_error(
3688                                     self,
3689                                     expr.span,
3690                                     ResolutionError::StructVariantUsedAsFunction(
3691                                         &*path_name)
3692                                 );
3693
3694                                 let msg = format!("did you mean to write: \
3695                                                      `{} {{ /* fields */ }}`?",
3696                                                     path_name);
3697                                 if self.emit_errors {
3698                                     self.session.fileline_help(expr.span, &msg);
3699                                 } else {
3700                                     self.session.span_help(expr.span, &msg);
3701                                 }
3702                             }
3703                         _ => {
3704                             // Keep reporting some errors even if they're ignored above.
3705                             self.resolve_path(expr.id, path, 0, ValueNS, true);
3706
3707                             let mut method_scope = false;
3708                             self.value_ribs.iter().rev().all(|rib| {
3709                                 method_scope = match rib.kind {
3710                                     MethodRibKind => true,
3711                                     ItemRibKind | ConstantItemRibKind => false,
3712                                     _ => return true, // Keep advancing
3713                                 };
3714                                 false // Stop advancing
3715                             });
3716
3717                             if method_scope && special_names::self_.as_str() == &path_name[..] {
3718                                 resolve_error(
3719                                     self,
3720                                     expr.span,
3721                                     ResolutionError::SelfNotAvailableInStaticMethod
3722                                 );
3723                             } else {
3724                                 let last_name = path.segments.last().unwrap().identifier.name;
3725                                 let mut msg = match self.find_fallback_in_self_type(last_name) {
3726                                     NoSuggestion => {
3727                                         // limit search to 5 to reduce the number
3728                                         // of stupid suggestions
3729                                         self.find_best_match_for_name(&path_name)
3730                                                             .map_or("".to_string(),
3731                                                                     |x| format!("`{}`", x))
3732                                     }
3733                                     Field => format!("`self.{}`", path_name),
3734                                     Method |
3735                                     TraitItem =>
3736                                         format!("to call `self.{}`", path_name),
3737                                     TraitMethod(path_str) |
3738                                     StaticMethod(path_str) =>
3739                                         format!("to call `{}::{}`", path_str, path_name)
3740                                 };
3741
3742                                 if !msg.is_empty() {
3743                                     msg = format!(". Did you mean {}?", msg)
3744                                 }
3745
3746                                 resolve_error(self,
3747                                               expr.span,
3748                                               ResolutionError::UnresolvedName(&*path_name,
3749                                                                                &*msg));
3750                             }
3751                         }
3752                     }
3753                 }
3754
3755                 visit::walk_expr(self, expr);
3756             }
3757
3758             ExprStruct(ref path, _, _) => {
3759                 // Resolve the path to the structure it goes to. We don't
3760                 // check to ensure that the path is actually a structure; that
3761                 // is checked later during typeck.
3762                 match self.resolve_path(expr.id, path, 0, TypeNS, false) {
3763                     Some(definition) => self.record_def(expr.id, definition),
3764                     None => {
3765                         debug!("(resolving expression) didn't find struct def",);
3766
3767                         resolve_error(self,
3768                                       path.span,
3769                                       ResolutionError::DoesNotNameAStruct(
3770                                                                 &*path_names_to_string(path, 0))
3771                                      );
3772                     }
3773                 }
3774
3775                 visit::walk_expr(self, expr);
3776             }
3777
3778             ExprLoop(_, Some(label)) | ExprWhile(_, _, Some(label)) => {
3779                 self.with_label_rib(|this| {
3780                     let def_like = DlDef(DefLabel(expr.id));
3781
3782                     {
3783                         let rib = this.label_ribs.last_mut().unwrap();
3784                         let renamed = mtwt::resolve(label);
3785                         rib.bindings.insert(renamed, def_like);
3786                     }
3787
3788                     visit::walk_expr(this, expr);
3789                 })
3790             }
3791
3792             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
3793                 let renamed = mtwt::resolve(label.node);
3794                 match self.search_label(renamed) {
3795                     None => {
3796                         resolve_error(self,
3797                                       label.span,
3798                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
3799                     }
3800                     Some(DlDef(def @ DefLabel(_))) => {
3801                         // Since this def is a label, it is never read.
3802                         self.record_def(expr.id, PathResolution {
3803                             base_def: def,
3804                             last_private: LastMod(AllPublic),
3805                             depth: 0
3806                         })
3807                     }
3808                     Some(_) => {
3809                         self.session.span_bug(expr.span,
3810                                               "label wasn't mapped to a \
3811                                                label def!")
3812                     }
3813                 }
3814             }
3815
3816             _ => {
3817                 visit::walk_expr(self, expr);
3818             }
3819         }
3820     }
3821
3822     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3823         match expr.node {
3824             ExprField(_, name) => {
3825                 // FIXME(#6890): Even though you can't treat a method like a
3826                 // field, we need to add any trait methods we find that match
3827                 // the field name so that we can do some nice error reporting
3828                 // later on in typeck.
3829                 let traits = self.get_traits_containing_item(name.node);
3830                 self.trait_map.insert(expr.id, traits);
3831             }
3832             ExprMethodCall(name, _, _) => {
3833                 debug!("(recording candidate traits for expr) recording \
3834                         traits for {}",
3835                        expr.id);
3836                 let traits = self.get_traits_containing_item(name.node);
3837                 self.trait_map.insert(expr.id, traits);
3838             }
3839             _ => {
3840                 // Nothing to do.
3841             }
3842         }
3843     }
3844
3845     fn get_traits_containing_item(&mut self, name: Name) -> Vec<DefId> {
3846         debug!("(getting traits containing item) looking for '{}'",
3847                name);
3848
3849         fn add_trait_info(found_traits: &mut Vec<DefId>,
3850                           trait_def_id: DefId,
3851                           name: Name) {
3852             debug!("(adding trait info) found trait {:?} for method '{}'",
3853                 trait_def_id,
3854                 name);
3855             found_traits.push(trait_def_id);
3856         }
3857
3858         let mut found_traits = Vec::new();
3859         let mut search_module = self.current_module.clone();
3860         loop {
3861             // Look for the current trait.
3862             match self.current_trait_ref {
3863                 Some((trait_def_id, _)) => {
3864                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3865                         add_trait_info(&mut found_traits, trait_def_id, name);
3866                     }
3867                 }
3868                 None => {} // Nothing to do.
3869             }
3870
3871             // Look for trait children.
3872             build_reduced_graph::populate_module_if_necessary(self, &search_module);
3873
3874             {
3875                 for (_, child_names) in search_module.children.borrow().iter() {
3876                     let def = match child_names.def_for_namespace(TypeNS) {
3877                         Some(def) => def,
3878                         None => continue
3879                     };
3880                     let trait_def_id = match def {
3881                         DefTrait(trait_def_id) => trait_def_id,
3882                         _ => continue,
3883                     };
3884                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3885                         add_trait_info(&mut found_traits, trait_def_id, name);
3886                     }
3887                 }
3888             }
3889
3890             // Look for imports.
3891             for (_, import) in search_module.import_resolutions.borrow().iter() {
3892                 let target = match import.target_for_namespace(TypeNS) {
3893                     None => continue,
3894                     Some(target) => target,
3895                 };
3896                 let did = match target.bindings.def_for_namespace(TypeNS) {
3897                     Some(DefTrait(trait_def_id)) => trait_def_id,
3898                     Some(..) | None => continue,
3899                 };
3900                 if self.trait_item_map.contains_key(&(name, did)) {
3901                     add_trait_info(&mut found_traits, did, name);
3902                     let id = import.type_id;
3903                     self.used_imports.insert((id, TypeNS));
3904                     let trait_name = self.get_trait_name(did);
3905                     self.record_import_use(id, trait_name);
3906                     if let Some(DefId{krate: kid, ..}) = target.target_module.def_id.get() {
3907                         self.used_crates.insert(kid);
3908                     }
3909                 }
3910             }
3911
3912             match search_module.parent_link.clone() {
3913                 NoParentLink | ModuleParentLink(..) => break,
3914                 BlockParentLink(parent_module, _) => {
3915                     search_module = parent_module.upgrade().unwrap();
3916                 }
3917             }
3918         }
3919
3920         found_traits
3921     }
3922
3923     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3924         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3925         assert!(match resolution.last_private {LastImport{..} => false, _ => true},
3926                 "Import should only be used for `use` directives");
3927
3928         if let Some(prev_res) = self.def_map.borrow_mut().insert(node_id, resolution) {
3929             let span = self.ast_map.opt_span(node_id).unwrap_or(codemap::DUMMY_SP);
3930             self.session.span_bug(span, &format!("path resolved multiple times \
3931                                                   ({:?} before, {:?} now)",
3932                                                  prev_res, resolution));
3933         }
3934     }
3935
3936     fn enforce_default_binding_mode(&mut self,
3937                                         pat: &Pat,
3938                                         pat_binding_mode: BindingMode,
3939                                         descr: &str) {
3940         match pat_binding_mode {
3941             BindByValue(_) => {}
3942             BindByRef(..) => {
3943                 resolve_error(self,
3944                               pat.span,
3945                               ResolutionError::CannotUseRefBindingModeWith(descr));
3946             }
3947         }
3948     }
3949
3950     //
3951     // Diagnostics
3952     //
3953     // Diagnostics are not particularly efficient, because they're rarely
3954     // hit.
3955     //
3956
3957     #[allow(dead_code)]   // useful for debugging
3958     fn dump_module(&mut self, module_: Rc<Module>) {
3959         debug!("Dump of module `{}`:", module_to_string(&*module_));
3960
3961         debug!("Children:");
3962         build_reduced_graph::populate_module_if_necessary(self, &module_);
3963         for (&name, _) in module_.children.borrow().iter() {
3964             debug!("* {}", name);
3965         }
3966
3967         debug!("Import resolutions:");
3968         let import_resolutions = module_.import_resolutions.borrow();
3969         for (&name, import_resolution) in import_resolutions.iter() {
3970             let value_repr;
3971             match import_resolution.target_for_namespace(ValueNS) {
3972                 None => { value_repr = "".to_string(); }
3973                 Some(_) => {
3974                     value_repr = " value:?".to_string();
3975                     // FIXME #4954
3976                 }
3977             }
3978
3979             let type_repr;
3980             match import_resolution.target_for_namespace(TypeNS) {
3981                 None => { type_repr = "".to_string(); }
3982                 Some(_) => {
3983                     type_repr = " type:?".to_string();
3984                     // FIXME #4954
3985                 }
3986             }
3987
3988             debug!("* {}:{}{}", name, value_repr, type_repr);
3989         }
3990     }
3991 }
3992
3993
3994 fn names_to_string(names: &[Name]) -> String {
3995     let mut first = true;
3996     let mut result = String::new();
3997     for name in names {
3998         if first {
3999             first = false
4000         } else {
4001             result.push_str("::")
4002         }
4003         result.push_str(&name.as_str());
4004     };
4005     result
4006 }
4007
4008 fn path_names_to_string(path: &Path, depth: usize) -> String {
4009     let names: Vec<ast::Name> = path.segments[..path.segments.len()-depth]
4010                                     .iter()
4011                                     .map(|seg| seg.identifier.name)
4012                                     .collect();
4013     names_to_string(&names[..])
4014 }
4015
4016 /// A somewhat inefficient routine to obtain the name of a module.
4017 fn module_to_string(module: &Module) -> String {
4018     let mut names = Vec::new();
4019
4020     fn collect_mod(names: &mut Vec<ast::Name>, module: &Module) {
4021         match module.parent_link {
4022             NoParentLink => {}
4023             ModuleParentLink(ref module, name) => {
4024                 names.push(name);
4025                 collect_mod(names, &*module.upgrade().unwrap());
4026             }
4027             BlockParentLink(ref module, _) => {
4028                 // danger, shouldn't be ident?
4029                 names.push(special_idents::opaque.name);
4030                 collect_mod(names, &*module.upgrade().unwrap());
4031             }
4032         }
4033     }
4034     collect_mod(&mut names, module);
4035
4036     if names.is_empty() {
4037         return "???".to_string();
4038     }
4039     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
4040 }
4041
4042
4043 pub struct CrateMap {
4044     pub def_map: DefMap,
4045     pub freevars: RefCell<FreevarMap>,
4046     pub export_map: ExportMap,
4047     pub trait_map: TraitMap,
4048     pub external_exports: ExternalExports,
4049     pub glob_map: Option<GlobMap>
4050 }
4051
4052 #[derive(PartialEq,Copy, Clone)]
4053 pub enum MakeGlobMap {
4054     Yes,
4055     No
4056 }
4057
4058 /// Entry point to crate resolution.
4059 pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
4060                                ast_map: &'a hir_map::Map<'tcx>,
4061                                make_glob_map: MakeGlobMap)
4062                                -> CrateMap {
4063     let krate = ast_map.krate();
4064     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, None);
4065
4066     resolver.resolve_crate(krate);
4067     session.abort_if_errors();
4068
4069     check_unused::check_crate(&mut resolver, krate);
4070
4071     CrateMap {
4072         def_map: resolver.def_map,
4073         freevars: resolver.freevars,
4074         export_map: resolver.export_map,
4075         trait_map: resolver.trait_map,
4076         external_exports: resolver.external_exports,
4077         glob_map: if resolver.make_glob_map {
4078                         Some(resolver.glob_map)
4079                     } else {
4080                         None
4081                     },
4082     }
4083 }
4084
4085 /// Builds a name resolution walker to be used within this module,
4086 /// or used externally, with an optional callback function.
4087 ///
4088 /// The callback takes a &mut bool which allows callbacks to end a
4089 /// walk when set to true, passing through the rest of the walk, while
4090 /// preserving the ribs + current module. This allows resolve_path
4091 /// calls to be made with the correct scope info. The node in the
4092 /// callback corresponds to the current node in the walk.
4093 pub fn create_resolver<'a, 'tcx>(session: &'a Session,
4094                                  ast_map: &'a hir_map::Map<'tcx>,
4095                                  krate: &'a Crate,
4096                                  make_glob_map: MakeGlobMap,
4097                                  callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>)
4098                                  -> Resolver<'a, 'tcx> {
4099     let mut resolver = Resolver::new(session, ast_map, krate.span, make_glob_map);
4100
4101     resolver.callback = callback;
4102
4103     build_reduced_graph::build_reduced_graph(&mut resolver, krate);
4104     session.abort_if_errors();
4105
4106     resolve_imports::resolve_imports(&mut resolver);
4107     session.abort_if_errors();
4108
4109     record_exports::record(&mut resolver);
4110     session.abort_if_errors();
4111
4112     resolver
4113 }
4114
4115 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }