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