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 #![crate_name = "rustc_resolve"]
  12 #![unstable(feature = "rustc_private", issue = "27812")]
  13 #![crate_type = "dylib"]
  14 #![crate_type = "rlib"]
  15 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  16       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  17       html_root_url = "https://doc.rust-lang.org/nightly/")]
  18
  19 #![feature(associated_consts)]
  20 #![feature(borrow_state)]
  21 #![feature(rustc_diagnostic_macros)]
  22 #![feature(rustc_private)]
  23 #![feature(staged_api)]
  24
  25 #[macro_use]
  26 extern crate log;
  27 #[macro_use]
  28 extern crate syntax;
  29 extern crate arena;
  30 #[macro_use]
  31 #[no_link]
  32 extern crate rustc_bitflags;
  33 extern crate rustc_front;
  34 extern crate rustc;
  35
  36 use self::PatternBindingMode::*;
  37 use self::Namespace::*;
  38 use self::NamespaceResult::*;
  39 use self::ResolveResult::*;
  40 use self::FallbackSuggestion::*;
  41 use self::TypeParameters::*;
  42 use self::RibKind::*;
  43 use self::UseLexicalScopeFlag::*;
  44 use self::ModulePrefixResult::*;
  45 use self::AssocItemResolveResult::*;
  46 use self::NameSearchType::*;
  47 use self::BareIdentifierPatternResolution::*;
  48 use self::ParentLink::*;
  49 use self::FallbackChecks::*;
  50
  51 use rustc::front::map as hir_map;
  52 use rustc::session::Session;
  53 use rustc::lint;
  54 use rustc::middle::cstore::{CrateStore, DefLike, DlDef};
  55 use rustc::middle::def::*;
  56 use rustc::middle::def_id::DefId;
  57 use rustc::middle::pat_util::pat_bindings;
  58 use rustc::middle::privacy::*;
  59 use rustc::middle::subst::{ParamSpace, FnSpace, TypeSpace};
  60 use rustc::middle::ty::{Freevar, FreevarMap, TraitMap, GlobMap};
  61 use rustc::util::nodemap::{NodeMap, DefIdSet, FnvHashMap};
  62
  63 use syntax::ast;
  64 use syntax::ast::{CRATE_NODE_ID, Name, NodeId, CrateNum, TyIs, TyI8, TyI16, TyI32, TyI64};
  65 use syntax::ast::{TyUs, TyU8, TyU16, TyU32, TyU64, TyF64, TyF32};
  66 use syntax::attr::AttrMetaMethods;
  67 use syntax::codemap::{self, Span, Pos};
  68 use syntax::errors::DiagnosticBuilder;
  69 use syntax::parse::token::{self, special_names, special_idents};
  70 use syntax::util::lev_distance::find_best_match_for_name;
  71
  72 use rustc_front::intravisit::{self, FnKind, Visitor};
  73 use rustc_front::hir;
  74 use rustc_front::hir::{Arm, BindByRef, BindByValue, BindingMode, Block};
  75 use rustc_front::hir::Crate;
  76 use rustc_front::hir::{Expr, ExprAgain, ExprBreak, ExprCall, ExprField};
  77 use rustc_front::hir::{ExprLoop, ExprWhile, ExprMethodCall};
  78 use rustc_front::hir::{ExprPath, ExprStruct, FnDecl};
  79 use rustc_front::hir::{ForeignItemFn, ForeignItemStatic, Generics};
  80 use rustc_front::hir::{ImplItem, Item, ItemConst, ItemEnum, ItemExternCrate};
  81 use rustc_front::hir::{ItemFn, ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  82 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  83 use rustc_front::hir::Local;
  84 use rustc_front::hir::{Pat, PatEnum, PatIdent, PatLit, PatQPath};
  85 use rustc_front::hir::{PatRange, PatStruct, Path, PrimTy};
  86 use rustc_front::hir::{TraitRef, Ty, TyBool, TyChar, TyFloat, TyInt};
  87 use rustc_front::hir::{TyRptr, TyStr, TyUint, TyPath, TyPtr};
  88 use rustc_front::util::walk_pat;
  89
  90 use std::collections::{HashMap, HashSet};
  91 use std::cell::{Cell, RefCell};
  92 use std::fmt;
  93 use std::mem::replace;
  94 use std::rc::Rc;
  95
  96 use resolve_imports::{Target, ImportDirective, ImportResolutionPerNamespace};
  97 use resolve_imports::Shadowable;
  98
  99 // NB: This module needs to be declared first so diagnostics are
 100 // registered before they are used.
 101 pub mod diagnostics;
 102
 103 mod check_unused;
 104 mod build_reduced_graph;
 105 mod resolve_imports;
 106
 107 // Perform the callback, not walking deeper if the return is true
 108 macro_rules! execute_callback {
 109     ($node: expr, $walker: expr) => (
 110         if let Some(ref callback) = $walker.callback {
 111             if callback($node, &mut $walker.resolved) {
 112                 return;
 113             }
 114         }
 115     )
 116 }
 117
 118 enum SuggestionType {
 119     Macro(String),
 120     Function(token::InternedString),
 121     NotFound,
 122 }
 123
 124 pub enum ResolutionError<'a> {
 125     /// error E0260: name conflicts with an extern crate
 126     NameConflictsWithExternCrate(Name),
 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(DefId, Name),
 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, UnresolvedNameContext),
 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 /// Context of where `ResolutionError::UnresolvedName` arose.
 204 #[derive(Clone, PartialEq, Eq, Debug)]
 205 pub enum UnresolvedNameContext {
 206     /// `PathIsMod(id)` indicates that a given path, used in
 207     /// expression context, actually resolved to a module rather than
 208     /// a value. The `id` attached to the variant is the node id of
 209     /// the erroneous path expression.
 210     PathIsMod(ast::NodeId),
 211
 212     /// `Other` means we have no extra information about the context
 213     /// of the unresolved name error. (Maybe we could eliminate all
 214     /// such cases; but for now, this is an information-free default.)
 215     Other,
 216 }
 217
 218 fn resolve_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 219                                        span: syntax::codemap::Span,
 220                                        resolution_error: ResolutionError<'b>) {
 221     resolve_struct_error(resolver, span, resolution_error).emit();
 222 }
 223
 224 fn resolve_struct_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 225                                               span: syntax::codemap::Span,
 226                                               resolution_error: ResolutionError<'b>)
 227                                               -> DiagnosticBuilder<'a> {
 228     if !resolver.emit_errors {
 229         return resolver.session.diagnostic().struct_dummy();
 230     }
 231
 232     match resolution_error {
 233         ResolutionError::NameConflictsWithExternCrate(name) => {
 234             struct_span_err!(resolver.session,
 235                              span,
 236                              E0260,
 237                              "the name `{}` conflicts with an external crate \
 238                              that has been imported into this module",
 239                              name)
 240         }
 241         ResolutionError::TypeParametersFromOuterFunction => {
 242             struct_span_err!(resolver.session,
 243                              span,
 244                              E0401,
 245                              "can't use type parameters from outer function; try using a local \
 246                               type parameter instead")
 247         }
 248         ResolutionError::OuterTypeParameterContext => {
 249             struct_span_err!(resolver.session,
 250                              span,
 251                              E0402,
 252                              "cannot use an outer type parameter in this context")
 253         }
 254         ResolutionError::NameAlreadyUsedInTypeParameterList(name) => {
 255             struct_span_err!(resolver.session,
 256                              span,
 257                              E0403,
 258                              "the name `{}` is already used for a type parameter in this type \
 259                               parameter list",
 260                              name)
 261         }
 262         ResolutionError::IsNotATrait(name) => {
 263             struct_span_err!(resolver.session, span, E0404, "`{}` is not a trait", name)
 264         }
 265         ResolutionError::UndeclaredTraitName(name) => {
 266             struct_span_err!(resolver.session,
 267                              span,
 268                              E0405,
 269                              "use of undeclared trait name `{}`",
 270                              name)
 271         }
 272         ResolutionError::UndeclaredAssociatedType => {
 273             struct_span_err!(resolver.session, span, E0406, "undeclared associated type")
 274         }
 275         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 276             struct_span_err!(resolver.session,
 277                              span,
 278                              E0407,
 279                              "method `{}` is not a member of trait `{}`",
 280                              method,
 281                              trait_)
 282         }
 283         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 284             struct_span_err!(resolver.session,
 285                              span,
 286                              E0437,
 287                              "type `{}` is not a member of trait `{}`",
 288                              type_,
 289                              trait_)
 290         }
 291         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 292             struct_span_err!(resolver.session,
 293                              span,
 294                              E0438,
 295                              "const `{}` is not a member of trait `{}`",
 296                              const_,
 297                              trait_)
 298         }
 299         ResolutionError::VariableNotBoundInPattern(variable_name, pattern_number) => {
 300             struct_span_err!(resolver.session,
 301                              span,
 302                              E0408,
 303                              "variable `{}` from pattern #1 is not bound in pattern #{}",
 304                              variable_name,
 305                              pattern_number)
 306         }
 307         ResolutionError::VariableBoundWithDifferentMode(variable_name, pattern_number) => {
 308             struct_span_err!(resolver.session,
 309                              span,
 310                              E0409,
 311                              "variable `{}` is bound with different mode in pattern #{} than in \
 312                               pattern #1",
 313                              variable_name,
 314                              pattern_number)
 315         }
 316         ResolutionError::VariableNotBoundInParentPattern(variable_name, pattern_number) => {
 317             struct_span_err!(resolver.session,
 318                              span,
 319                              E0410,
 320                              "variable `{}` from pattern #{} is not bound in pattern #1",
 321                              variable_name,
 322                              pattern_number)
 323         }
 324         ResolutionError::SelfUsedOutsideImplOrTrait => {
 325             struct_span_err!(resolver.session,
 326                              span,
 327                              E0411,
 328                              "use of `Self` outside of an impl or trait")
 329         }
 330         ResolutionError::UseOfUndeclared(kind, name) => {
 331             struct_span_err!(resolver.session,
 332                              span,
 333                              E0412,
 334                              "use of undeclared {} `{}`",
 335                              kind,
 336                              name)
 337         }
 338         ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(name) => {
 339             struct_span_err!(resolver.session,
 340                              span,
 341                              E0413,
 342                              "declaration of `{}` shadows an enum variant \
 343                               or unit-like struct in scope",
 344                              name)
 345         }
 346         ResolutionError::OnlyIrrefutablePatternsAllowedHere(did, name) => {
 347             let mut err = struct_span_err!(resolver.session,
 348                                            span,
 349                                            E0414,
 350                                            "only irrefutable patterns allowed here");
 351             err.span_note(span,
 352                           "there already is a constant in scope sharing the same \
 353                            name as this pattern");
 354             if let Some(sp) = resolver.ast_map.span_if_local(did) {
 355                 err.span_note(sp, "constant defined here");
 356             }
 357             if let Some(directive) = resolver.current_module
 358                                              .import_resolutions
 359                                              .borrow()
 360                                              .get(&name) {
 361                 let item = resolver.ast_map.expect_item(directive.value_ns.id);
 362                 err.span_note(item.span, "constant imported here");
 363             }
 364             err
 365         }
 366         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 367             struct_span_err!(resolver.session,
 368                              span,
 369                              E0415,
 370                              "identifier `{}` is bound more than once in this parameter list",
 371                              identifier)
 372         }
 373         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 374             struct_span_err!(resolver.session,
 375                              span,
 376                              E0416,
 377                              "identifier `{}` is bound more than once in the same pattern",
 378                              identifier)
 379         }
 380         ResolutionError::StaticVariableReference => {
 381             struct_span_err!(resolver.session,
 382                              span,
 383                              E0417,
 384                              "static variables cannot be referenced in a pattern, use a \
 385                               `const` instead")
 386         }
 387         ResolutionError::NotAnEnumVariantStructOrConst(name) => {
 388             struct_span_err!(resolver.session,
 389                              span,
 390                              E0418,
 391                              "`{}` is not an enum variant, struct or const",
 392                              name)
 393         }
 394         ResolutionError::UnresolvedEnumVariantStructOrConst(name) => {
 395             struct_span_err!(resolver.session,
 396                              span,
 397                              E0419,
 398                              "unresolved enum variant, struct or const `{}`",
 399                              name)
 400         }
 401         ResolutionError::NotAnAssociatedConst(name) => {
 402             struct_span_err!(resolver.session,
 403                              span,
 404                              E0420,
 405                              "`{}` is not an associated const",
 406                              name)
 407         }
 408         ResolutionError::UnresolvedAssociatedConst(name) => {
 409             struct_span_err!(resolver.session,
 410                              span,
 411                              E0421,
 412                              "unresolved associated const `{}`",
 413                              name)
 414         }
 415         ResolutionError::DoesNotNameAStruct(name) => {
 416             struct_span_err!(resolver.session,
 417                              span,
 418                              E0422,
 419                              "`{}` does not name a structure",
 420                              name)
 421         }
 422         ResolutionError::StructVariantUsedAsFunction(path_name) => {
 423             struct_span_err!(resolver.session,
 424                              span,
 425                              E0423,
 426                              "`{}` is the name of a struct or struct variant, but this expression \
 427                              uses it like a function name",
 428                              path_name)
 429         }
 430         ResolutionError::SelfNotAvailableInStaticMethod => {
 431             struct_span_err!(resolver.session,
 432                              span,
 433                              E0424,
 434                              "`self` is not available in a static method. Maybe a `self` \
 435                              argument is missing?")
 436         }
 437         ResolutionError::UnresolvedName(path, msg, context) => {
 438             let mut err = struct_span_err!(resolver.session,
 439                                            span,
 440                                            E0425,
 441                                            "unresolved name `{}`{}",
 442                                            path,
 443                                            msg);
 444
 445             match context {
 446                 UnresolvedNameContext::Other => { } // no help available
 447                 UnresolvedNameContext::PathIsMod(id) => {
 448                     let mut help_msg = String::new();
 449                     let parent_id = resolver.ast_map.get_parent_node(id);
 450                     if let Some(hir_map::Node::NodeExpr(e)) = resolver.ast_map.find(parent_id) {
 451                         match e.node {
 452                             ExprField(_, ident) => {
 453                                 help_msg = format!("To reference an item from the \
 454                                                     `{module}` module, use \
 455                                                     `{module}::{ident}`",
 456                                                    module = &*path,
 457                                                    ident = ident.node);
 458                             }
 459                             ExprMethodCall(ident, _, _) => {
 460                                 help_msg = format!("To call a function from the \
 461                                                     `{module}` module, use \
 462                                                     `{module}::{ident}(..)`",
 463                                                    module = &*path,
 464                                                    ident = ident.node);
 465                             }
 466                             ExprCall(_, _) => {
 467                                 help_msg = format!("No function corresponds to `{module}(..)`",
 468                                                    module = &*path);
 469                             }
 470                             _ => { } // no help available
 471                         }
 472                     } else {
 473                         help_msg = format!("Module `{module}` cannot be the value of an expression",
 474                                            module = &*path);
 475                     }
 476
 477                     if !help_msg.is_empty() {
 478                         err.fileline_help(span, &help_msg);
 479                     }
 480                 }
 481             }
 482             err
 483         }
 484         ResolutionError::UndeclaredLabel(name) => {
 485             struct_span_err!(resolver.session,
 486                              span,
 487                              E0426,
 488                              "use of undeclared label `{}`",
 489                              name)
 490         }
 491         ResolutionError::CannotUseRefBindingModeWith(descr) => {
 492             struct_span_err!(resolver.session,
 493                              span,
 494                              E0427,
 495                              "cannot use `ref` binding mode with {}",
 496                              descr)
 497         }
 498         ResolutionError::DuplicateDefinition(namespace, name) => {
 499             struct_span_err!(resolver.session,
 500                              span,
 501                              E0428,
 502                              "duplicate definition of {} `{}`",
 503                              namespace,
 504                              name)
 505         }
 506         ResolutionError::SelfImportsOnlyAllowedWithin => {
 507             struct_span_err!(resolver.session,
 508                              span,
 509                              E0429,
 510                              "{}",
 511                              "`self` imports are only allowed within a { } list")
 512         }
 513         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 514             struct_span_err!(resolver.session,
 515                              span,
 516                              E0430,
 517                              "`self` import can only appear once in the list")
 518         }
 519         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 520             struct_span_err!(resolver.session,
 521                              span,
 522                              E0431,
 523                              "`self` import can only appear in an import list with a \
 524                               non-empty prefix")
 525         }
 526         ResolutionError::UnresolvedImport(name) => {
 527             let msg = match name {
 528                 Some((n, p)) => format!("unresolved import `{}`{}", n, p),
 529                 None => "unresolved import".to_owned(),
 530             };
 531             struct_span_err!(resolver.session, span, E0432, "{}", msg)
 532         }
 533         ResolutionError::FailedToResolve(msg) => {
 534             struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg)
 535         }
 536         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 537             struct_span_err!(resolver.session,
 538                              span,
 539                              E0434,
 540                              "{}",
 541                              "can't capture dynamic environment in a fn item; use the || { ... } \
 542                               closure form instead")
 543         }
 544         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 545             struct_span_err!(resolver.session,
 546                              span,
 547                              E0435,
 548                              "attempt to use a non-constant value in a constant")
 549         }
 550     }
 551 }
 552
 553 #[derive(Copy, Clone)]
 554 struct BindingInfo {
 555     span: Span,
 556     binding_mode: BindingMode,
 557 }
 558
 559 // Map from the name in a pattern to its binding mode.
 560 type BindingMap = HashMap<Name, BindingInfo>;
 561
 562 #[derive(Copy, Clone, PartialEq)]
 563 enum PatternBindingMode {
 564     RefutableMode,
 565     LocalIrrefutableMode,
 566     ArgumentIrrefutableMode,
 567 }
 568
 569 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 570 pub enum Namespace {
 571     TypeNS,
 572     ValueNS,
 573 }
 574
 575 /// A NamespaceResult represents the result of resolving an import in
 576 /// a particular namespace. The result is either definitely-resolved,
 577 /// definitely- unresolved, or unknown.
 578 #[derive(Clone)]
 579 enum NamespaceResult<'a> {
 580     /// Means that resolve hasn't gathered enough information yet to determine
 581     /// whether the name is bound in this namespace. (That is, it hasn't
 582     /// resolved all `use` directives yet.)
 583     UnknownResult,
 584     /// Means that resolve has determined that the name is definitely
 585     /// not bound in the namespace.
 586     UnboundResult,
 587     /// Means that resolve has determined that the name is bound in the Module
 588     /// argument, and specified by the NameBinding argument.
 589     BoundResult(Module<'a>, NameBinding<'a>),
 590 }
 591
 592 impl<'a> NamespaceResult<'a> {
 593     fn is_unknown(&self) -> bool {
 594         match *self {
 595             UnknownResult => true,
 596             _ => false,
 597         }
 598     }
 599     fn is_unbound(&self) -> bool {
 600         match *self {
 601             UnboundResult => true,
 602             _ => false,
 603         }
 604     }
 605 }
 606
 607 impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
 608     fn visit_nested_item(&mut self, item: hir::ItemId) {
 609         self.visit_item(self.ast_map.expect_item(item.id))
 610     }
 611     fn visit_item(&mut self, item: &Item) {
 612         execute_callback!(hir_map::Node::NodeItem(item), self);
 613         self.resolve_item(item);
 614     }
 615     fn visit_arm(&mut self, arm: &Arm) {
 616         self.resolve_arm(arm);
 617     }
 618     fn visit_block(&mut self, block: &Block) {
 619         execute_callback!(hir_map::Node::NodeBlock(block), self);
 620         self.resolve_block(block);
 621     }
 622     fn visit_expr(&mut self, expr: &Expr) {
 623         execute_callback!(hir_map::Node::NodeExpr(expr), self);
 624         self.resolve_expr(expr);
 625     }
 626     fn visit_local(&mut self, local: &Local) {
 627         execute_callback!(hir_map::Node::NodeLocal(&*local.pat), self);
 628         self.resolve_local(local);
 629     }
 630     fn visit_ty(&mut self, ty: &Ty) {
 631         self.resolve_type(ty);
 632     }
 633     fn visit_generics(&mut self, generics: &Generics) {
 634         self.resolve_generics(generics);
 635     }
 636     fn visit_poly_trait_ref(&mut self, tref: &hir::PolyTraitRef, m: &hir::TraitBoundModifier) {
 637         match self.resolve_trait_reference(tref.trait_ref.ref_id, &tref.trait_ref.path, 0) {
 638             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
 639             Err(_) => {
 640                 // error already reported
 641                 self.record_def(tref.trait_ref.ref_id, err_path_resolution())
 642             }
 643         }
 644         intravisit::walk_poly_trait_ref(self, tref, m);
 645     }
 646     fn visit_variant(&mut self,
 647                      variant: &hir::Variant,
 648                      generics: &Generics,
 649                      item_id: ast::NodeId) {
 650         execute_callback!(hir_map::Node::NodeVariant(variant), self);
 651         if let Some(ref dis_expr) = variant.node.disr_expr {
 652             // resolve the discriminator expr as a constant
 653             self.with_constant_rib(|this| {
 654                 this.visit_expr(dis_expr);
 655             });
 656         }
 657
 658         // `intravisit::walk_variant` without the discriminant expression.
 659         self.visit_variant_data(&variant.node.data,
 660                                 variant.node.name,
 661                                 generics,
 662                                 item_id,
 663                                 variant.span);
 664     }
 665     fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem) {
 666         execute_callback!(hir_map::Node::NodeForeignItem(foreign_item), self);
 667         let type_parameters = match foreign_item.node {
 668             ForeignItemFn(_, ref generics) => {
 669                 HasTypeParameters(generics, FnSpace, ItemRibKind)
 670             }
 671             ForeignItemStatic(..) => NoTypeParameters,
 672         };
 673         self.with_type_parameter_rib(type_parameters, |this| {
 674             intravisit::walk_foreign_item(this, foreign_item);
 675         });
 676     }
 677     fn visit_fn(&mut self,
 678                 function_kind: FnKind<'v>,
 679                 declaration: &'v FnDecl,
 680                 block: &'v Block,
 681                 _: Span,
 682                 node_id: NodeId) {
 683         let rib_kind = match function_kind {
 684             FnKind::ItemFn(_, generics, _, _, _, _) => {
 685                 self.visit_generics(generics);
 686                 ItemRibKind
 687             }
 688             FnKind::Method(_, sig, _) => {
 689                 self.visit_generics(&sig.generics);
 690                 self.visit_explicit_self(&sig.explicit_self);
 691                 MethodRibKind
 692             }
 693             FnKind::Closure => ClosureRibKind(node_id),
 694         };
 695         self.resolve_function(rib_kind, declaration, block);
 696     }
 697 }
 698
 699 type ErrorMessage = Option<(Span, String)>;
 700
 701 enum ResolveResult<T> {
 702     Failed(ErrorMessage), // Failed to resolve the name, optional helpful error message.
 703     Indeterminate, // Couldn't determine due to unresolved globs.
 704     Success(T), // Successfully resolved the import.
 705 }
 706
 707 impl<T> ResolveResult<T> {
 708     fn success(&self) -> bool {
 709         match *self {
 710             Success(_) => true,
 711             _ => false,
 712         }
 713     }
 714 }
 715
 716 enum FallbackSuggestion {
 717     NoSuggestion,
 718     Field,
 719     Method,
 720     TraitItem,
 721     StaticMethod(String),
 722     TraitMethod(String),
 723 }
 724
 725 #[derive(Copy, Clone)]
 726 enum TypeParameters<'a> {
 727     NoTypeParameters,
 728     HasTypeParameters(// Type parameters.
 729                       &'a Generics,
 730
 731                       // Identifies the things that these parameters
 732                       // were declared on (type, fn, etc)
 733                       ParamSpace,
 734
 735                       // The kind of the rib used for type parameters.
 736                       RibKind),
 737 }
 738
 739 // The rib kind controls the translation of local
 740 // definitions (`DefLocal`) to upvars (`DefUpvar`).
 741 #[derive(Copy, Clone, Debug)]
 742 enum RibKind {
 743     // No translation needs to be applied.
 744     NormalRibKind,
 745
 746     // We passed through a closure scope at the given node ID.
 747     // Translate upvars as appropriate.
 748     ClosureRibKind(NodeId /* func id */),
 749
 750     // We passed through an impl or trait and are now in one of its
 751     // methods. Allow references to ty params that impl or trait
 752     // binds. Disallow any other upvars (including other ty params that are
 753     // upvars).
 754     MethodRibKind,
 755
 756     // We passed through an item scope. Disallow upvars.
 757     ItemRibKind,
 758
 759     // We're in a constant item. Can't refer to dynamic stuff.
 760     ConstantItemRibKind,
 761 }
 762
 763 #[derive(Copy, Clone)]
 764 enum UseLexicalScopeFlag {
 765     DontUseLexicalScope,
 766     UseLexicalScope,
 767 }
 768
 769 enum ModulePrefixResult<'a> {
 770     NoPrefixFound,
 771     PrefixFound(Module<'a>, usize),
 772 }
 773
 774 #[derive(Copy, Clone)]
 775 enum AssocItemResolveResult {
 776     /// Syntax such as `<T>::item`, which can't be resolved until type
 777     /// checking.
 778     TypecheckRequired,
 779     /// We should have been able to resolve the associated item.
 780     ResolveAttempt(Option<PathResolution>),
 781 }
 782
 783 #[derive(Copy, Clone, PartialEq)]
 784 enum NameSearchType {
 785     /// We're doing a name search in order to resolve a `use` directive.
 786     ImportSearch,
 787
 788     /// We're doing a name search in order to resolve a path type, a path
 789     /// expression, or a path pattern.
 790     PathSearch,
 791 }
 792
 793 #[derive(Copy, Clone)]
 794 enum BareIdentifierPatternResolution {
 795     FoundStructOrEnumVariant(Def, LastPrivate),
 796     FoundConst(Def, LastPrivate, Name),
 797     BareIdentifierPatternUnresolved,
 798 }
 799
 800 /// One local scope.
 801 #[derive(Debug)]
 802 struct Rib {
 803     bindings: HashMap<Name, DefLike>,
 804     kind: RibKind,
 805 }
 806
 807 impl Rib {
 808     fn new(kind: RibKind) -> Rib {
 809         Rib {
 810             bindings: HashMap::new(),
 811             kind: kind,
 812         }
 813     }
 814 }
 815
 816 /// A definition along with the index of the rib it was found on
 817 struct LocalDef {
 818     ribs: Option<(Namespace, usize)>,
 819     def: Def,
 820 }
 821
 822 impl LocalDef {
 823     fn from_def(def: Def) -> Self {
 824         LocalDef {
 825             ribs: None,
 826             def: def,
 827         }
 828     }
 829 }
 830
 831 /// The link from a module up to its nearest parent node.
 832 #[derive(Clone,Debug)]
 833 enum ParentLink<'a> {
 834     NoParentLink,
 835     ModuleParentLink(Module<'a>, Name),
 836     BlockParentLink(Module<'a>, NodeId),
 837 }
 838
 839 /// One node in the tree of modules.
 840 pub struct ModuleS<'a> {
 841     parent_link: ParentLink<'a>,
 842     def: Cell<Option<Def>>,
 843     is_public: bool,
 844
 845     children: RefCell<HashMap<Name, NameBindings<'a>>>,
 846     imports: RefCell<Vec<ImportDirective>>,
 847
 848     // The external module children of this node that were declared with
 849     // `extern crate`.
 850     external_module_children: RefCell<HashMap<Name, Module<'a>>>,
 851
 852     // The anonymous children of this node. Anonymous children are pseudo-
 853     // modules that are implicitly created around items contained within
 854     // blocks.
 855     //
 856     // For example, if we have this:
 857     //
 858     //  fn f() {
 859     //      fn g() {
 860     //          ...
 861     //      }
 862     //  }
 863     //
 864     // There will be an anonymous module created around `g` with the ID of the
 865     // entry block for `f`.
 866     anonymous_children: RefCell<NodeMap<Module<'a>>>,
 867
 868     // The status of resolving each import in this module.
 869     import_resolutions: RefCell<HashMap<Name, ImportResolutionPerNamespace<'a>>>,
 870
 871     // The number of unresolved globs that this module exports.
 872     glob_count: Cell<usize>,
 873
 874     // The number of unresolved pub imports (both regular and globs) in this module
 875     pub_count: Cell<usize>,
 876
 877     // The number of unresolved pub glob imports in this module
 878     pub_glob_count: Cell<usize>,
 879
 880     // The index of the import we're resolving.
 881     resolved_import_count: Cell<usize>,
 882
 883     // Whether this module is populated. If not populated, any attempt to
 884     // access the children must be preceded with a
 885     // `populate_module_if_necessary` call.
 886     populated: Cell<bool>,
 887 }
 888
 889 pub type Module<'a> = &'a ModuleS<'a>;
 890
 891 impl<'a> ModuleS<'a> {
 892     fn new(parent_link: ParentLink<'a>, def: Option<Def>, external: bool, is_public: bool) -> Self {
 893         ModuleS {
 894             parent_link: parent_link,
 895             def: Cell::new(def),
 896             is_public: is_public,
 897             children: RefCell::new(HashMap::new()),
 898             imports: RefCell::new(Vec::new()),
 899             external_module_children: RefCell::new(HashMap::new()),
 900             anonymous_children: RefCell::new(NodeMap()),
 901             import_resolutions: RefCell::new(HashMap::new()),
 902             glob_count: Cell::new(0),
 903             pub_count: Cell::new(0),
 904             pub_glob_count: Cell::new(0),
 905             resolved_import_count: Cell::new(0),
 906             populated: Cell::new(!external),
 907         }
 908     }
 909
 910     fn def_id(&self) -> Option<DefId> {
 911         self.def.get().as_ref().map(Def::def_id)
 912     }
 913
 914     fn is_normal(&self) -> bool {
 915         match self.def.get() {
 916             Some(DefMod(_)) | Some(DefForeignMod(_)) => true,
 917             _ => false,
 918         }
 919     }
 920
 921     fn is_trait(&self) -> bool {
 922         match self.def.get() {
 923             Some(DefTrait(_)) => true,
 924             _ => false,
 925         }
 926     }
 927
 928     fn all_imports_resolved(&self) -> bool {
 929         if self.imports.borrow_state() == ::std::cell::BorrowState::Writing {
 930             // it is currently being resolved ! so nope
 931             false
 932         } else {
 933             self.imports.borrow().len() == self.resolved_import_count.get()
 934         }
 935     }
 936
 937     pub fn inc_glob_count(&self) {
 938         self.glob_count.set(self.glob_count.get() + 1);
 939     }
 940     pub fn dec_glob_count(&self) {
 941         assert!(self.glob_count.get() > 0);
 942         self.glob_count.set(self.glob_count.get() - 1);
 943     }
 944     pub fn inc_pub_count(&self) {
 945         self.pub_count.set(self.pub_count.get() + 1);
 946     }
 947     pub fn dec_pub_count(&self) {
 948         assert!(self.pub_count.get() > 0);
 949         self.pub_count.set(self.pub_count.get() - 1);
 950     }
 951     pub fn inc_pub_glob_count(&self) {
 952         self.pub_glob_count.set(self.pub_glob_count.get() + 1);
 953     }
 954     pub fn dec_pub_glob_count(&self) {
 955         assert!(self.pub_glob_count.get() > 0);
 956         self.pub_glob_count.set(self.pub_glob_count.get() - 1);
 957     }
 958 }
 959
 960 impl<'a> fmt::Debug for ModuleS<'a> {
 961     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 962         write!(f,
 963                "{:?}, {}",
 964                self.def,
 965                if self.is_public {
 966                    "public"
 967                } else {
 968                    "private"
 969                })
 970     }
 971 }
 972
 973 bitflags! {
 974     #[derive(Debug)]
 975     flags DefModifiers: u8 {
 976         // Enum variants are always considered `PUBLIC`, this is needed for `use Enum::Variant`
 977         // or `use Enum::*` to work on private enums.
 978         const PUBLIC     = 1 << 0,
 979         const IMPORTABLE = 1 << 1,
 980         // Variants are considered `PUBLIC`, but some of them live in private enums.
 981         // We need to track them to prohibit reexports like `pub use PrivEnum::Variant`.
 982         const PRIVATE_VARIANT = 1 << 2,
 983     }
 984 }
 985
 986 // Records a possibly-private value, type, or module definition.
 987 #[derive(Debug)]
 988 struct NsDef<'a> {
 989     modifiers: DefModifiers, // see note in ImportResolutionPerNamespace about how to use this
 990     def_or_module: DefOrModule<'a>,
 991     span: Option<Span>,
 992 }
 993
 994 #[derive(Debug)]
 995 enum DefOrModule<'a> {
 996     Def(Def),
 997     Module(Module<'a>),
 998 }
 999
1000 impl<'a> NsDef<'a> {
1001     fn create_from_module(module: Module<'a>, span: Option<Span>) -> Self {
1002         let modifiers = if module.is_public {
1003             DefModifiers::PUBLIC
1004         } else {
1005             DefModifiers::empty()
1006         } | DefModifiers::IMPORTABLE;
1007
1008         NsDef { modifiers: modifiers, def_or_module: DefOrModule::Module(module), span: span }
1009     }
1010
1011     fn create_from_def(def: Def, modifiers: DefModifiers, span: Option<Span>) -> Self {
1012         NsDef { modifiers: modifiers, def_or_module: DefOrModule::Def(def), span: span }
1013     }
1014
1015     fn module(&self) -> Option<Module<'a>> {
1016         match self.def_or_module {
1017             DefOrModule::Module(ref module) => Some(module),
1018             DefOrModule::Def(_) => None,
1019         }
1020     }
1021
1022     fn def(&self) -> Option<Def> {
1023         match self.def_or_module {
1024             DefOrModule::Def(def) => Some(def),
1025             DefOrModule::Module(ref module) => module.def.get(),
1026         }
1027     }
1028 }
1029
1030 // Records at most one definition that a name in a namespace is bound to
1031 #[derive(Clone,Debug)]
1032 pub struct NameBinding<'a>(Rc<RefCell<Option<NsDef<'a>>>>);
1033
1034 impl<'a> NameBinding<'a> {
1035     fn new() -> Self {
1036         NameBinding(Rc::new(RefCell::new(None)))
1037     }
1038
1039     fn create_from_module(module: Module<'a>) -> Self {
1040         NameBinding(Rc::new(RefCell::new(Some(NsDef::create_from_module(module, None)))))
1041     }
1042
1043     fn set(&self, ns_def: NsDef<'a>) {
1044         *self.0.borrow_mut() = Some(ns_def);
1045     }
1046
1047     fn set_modifiers(&self, modifiers: DefModifiers) {
1048         if let Some(ref mut ns_def) = *self.0.borrow_mut() {
1049             ns_def.modifiers = modifiers
1050         }
1051     }
1052
1053     fn borrow(&self) -> ::std::cell::Ref<Option<NsDef<'a>>> {
1054         self.0.borrow()
1055     }
1056
1057     // Lifted versions of the NsDef methods and fields
1058     fn def(&self) -> Option<Def> {
1059         self.borrow().as_ref().and_then(NsDef::def)
1060     }
1061     fn module(&self) -> Option<Module<'a>> {
1062         self.borrow().as_ref().and_then(NsDef::module)
1063     }
1064     fn span(&self) -> Option<Span> {
1065         self.borrow().as_ref().and_then(|def| def.span)
1066     }
1067     fn modifiers(&self) -> Option<DefModifiers> {
1068         self.borrow().as_ref().and_then(|def| Some(def.modifiers))
1069     }
1070
1071     fn defined(&self) -> bool {
1072         self.borrow().is_some()
1073     }
1074
1075     fn defined_with(&self, modifiers: DefModifiers) -> bool {
1076         self.modifiers().map(|m| m.contains(modifiers)).unwrap_or(false)
1077     }
1078
1079     fn is_public(&self) -> bool {
1080         self.defined_with(DefModifiers::PUBLIC)
1081     }
1082
1083     fn def_and_lp(&self) -> (Def, LastPrivate) {
1084         let def = self.def().unwrap();
1085         (def, LastMod(if self.is_public() { AllPublic } else { DependsOn(def.def_id()) }))
1086     }
1087 }
1088
1089 // Records the definitions (at most one for each namespace) that a name is
1090 // bound to.
1091 #[derive(Clone,Debug)]
1092 pub struct NameBindings<'a> {
1093     type_ns: NameBinding<'a>, // < Meaning in type namespace.
1094     value_ns: NameBinding<'a>, // < Meaning in value namespace.
1095 }
1096
1097 impl<'a> ::std::ops::Index<Namespace> for NameBindings<'a> {
1098     type Output = NameBinding<'a>;
1099     fn index(&self, namespace: Namespace) -> &NameBinding<'a> {
1100         match namespace { TypeNS => &self.type_ns, ValueNS => &self.value_ns }
1101     }
1102 }
1103
1104 impl<'a> NameBindings<'a> {
1105     fn new() -> Self {
1106         NameBindings {
1107             type_ns: NameBinding::new(),
1108             value_ns: NameBinding::new(),
1109         }
1110     }
1111
1112     /// Creates a new module in this set of name bindings.
1113     fn define_module(&self, module: Module<'a>, sp: Span) {
1114         self.type_ns.set(NsDef::create_from_module(module, Some(sp)));
1115     }
1116
1117     /// Records a type definition.
1118     fn define_type(&self, def: Def, sp: Span, modifiers: DefModifiers) {
1119         debug!("defining type for def {:?} with modifiers {:?}", def, modifiers);
1120         self.type_ns.set(NsDef::create_from_def(def, modifiers, Some(sp)));
1121     }
1122
1123     /// Records a value definition.
1124     fn define_value(&self, def: Def, sp: Span, modifiers: DefModifiers) {
1125         debug!("defining value for def {:?} with modifiers {:?}", def, modifiers);
1126         self.value_ns.set(NsDef::create_from_def(def, modifiers, Some(sp)));
1127     }
1128 }
1129
1130 /// Interns the names of the primitive types.
1131 struct PrimitiveTypeTable {
1132     primitive_types: HashMap<Name, PrimTy>,
1133 }
1134
1135 impl PrimitiveTypeTable {
1136     fn new() -> PrimitiveTypeTable {
1137         let mut table = PrimitiveTypeTable { primitive_types: HashMap::new() };
1138
1139         table.intern("bool", TyBool);
1140         table.intern("char", TyChar);
1141         table.intern("f32", TyFloat(TyF32));
1142         table.intern("f64", TyFloat(TyF64));
1143         table.intern("isize", TyInt(TyIs));
1144         table.intern("i8", TyInt(TyI8));
1145         table.intern("i16", TyInt(TyI16));
1146         table.intern("i32", TyInt(TyI32));
1147         table.intern("i64", TyInt(TyI64));
1148         table.intern("str", TyStr);
1149         table.intern("usize", TyUint(TyUs));
1150         table.intern("u8", TyUint(TyU8));
1151         table.intern("u16", TyUint(TyU16));
1152         table.intern("u32", TyUint(TyU32));
1153         table.intern("u64", TyUint(TyU64));
1154
1155         table
1156     }
1157
1158     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1159         self.primitive_types.insert(token::intern(string), primitive_type);
1160     }
1161 }
1162
1163 /// The main resolver class.
1164 pub struct Resolver<'a, 'tcx: 'a> {
1165     session: &'a Session,
1166
1167     ast_map: &'a hir_map::Map<'tcx>,
1168
1169     graph_root: Module<'a>,
1170
1171     trait_item_map: FnvHashMap<(Name, DefId), DefId>,
1172
1173     structs: FnvHashMap<DefId, Vec<Name>>,
1174
1175     // The number of imports that are currently unresolved.
1176     unresolved_imports: usize,
1177
1178     // The module that represents the current item scope.
1179     current_module: Module<'a>,
1180
1181     // The current set of local scopes, for values.
1182     // FIXME #4948: Reuse ribs to avoid allocation.
1183     value_ribs: Vec<Rib>,
1184
1185     // The current set of local scopes, for types.
1186     type_ribs: Vec<Rib>,
1187
1188     // The current set of local scopes, for labels.
1189     label_ribs: Vec<Rib>,
1190
1191     // The trait that the current context can refer to.
1192     current_trait_ref: Option<(DefId, TraitRef)>,
1193
1194     // The current self type if inside an impl (used for better errors).
1195     current_self_type: Option<Ty>,
1196
1197     // The idents for the primitive types.
1198     primitive_type_table: PrimitiveTypeTable,
1199
1200     def_map: RefCell<DefMap>,
1201     freevars: FreevarMap,
1202     freevars_seen: NodeMap<NodeMap<usize>>,
1203     export_map: ExportMap,
1204     trait_map: TraitMap,
1205     external_exports: ExternalExports,
1206
1207     // Whether or not to print error messages. Can be set to true
1208     // when getting additional info for error message suggestions,
1209     // so as to avoid printing duplicate errors
1210     emit_errors: bool,
1211
1212     make_glob_map: bool,
1213     // Maps imports to the names of items actually imported (this actually maps
1214     // all imports, but only glob imports are actually interesting).
1215     glob_map: GlobMap,
1216
1217     used_imports: HashSet<(NodeId, Namespace)>,
1218     used_crates: HashSet<CrateNum>,
1219
1220     // Callback function for intercepting walks
1221     callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>,
1222     // The intention is that the callback modifies this flag.
1223     // Once set, the resolver falls out of the walk, preserving the ribs.
1224     resolved: bool,
1225
1226     arenas: &'a ResolverArenas<'a>,
1227 }
1228
1229 pub struct ResolverArenas<'a> {
1230     modules: arena::TypedArena<ModuleS<'a>>,
1231 }
1232
1233 #[derive(PartialEq)]
1234 enum FallbackChecks {
1235     Everything,
1236     OnlyTraitAndStatics,
1237 }
1238
1239 impl<'a, 'tcx> Resolver<'a, 'tcx> {
1240     fn new(session: &'a Session,
1241            ast_map: &'a hir_map::Map<'tcx>,
1242            make_glob_map: MakeGlobMap,
1243            arenas: &'a ResolverArenas<'a>)
1244            -> Resolver<'a, 'tcx> {
1245         let root_def_id = ast_map.local_def_id(CRATE_NODE_ID);
1246         let graph_root = ModuleS::new(NoParentLink, Some(DefMod(root_def_id)), false, true);
1247         let graph_root = arenas.modules.alloc(graph_root);
1248
1249         Resolver {
1250             session: session,
1251
1252             ast_map: ast_map,
1253
1254             // The outermost module has def ID 0; this is not reflected in the
1255             // AST.
1256             graph_root: graph_root,
1257
1258             trait_item_map: FnvHashMap(),
1259             structs: FnvHashMap(),
1260
1261             unresolved_imports: 0,
1262
1263             current_module: graph_root,
1264             value_ribs: Vec::new(),
1265             type_ribs: Vec::new(),
1266             label_ribs: Vec::new(),
1267
1268             current_trait_ref: None,
1269             current_self_type: None,
1270
1271             primitive_type_table: PrimitiveTypeTable::new(),
1272
1273             def_map: RefCell::new(NodeMap()),
1274             freevars: NodeMap(),
1275             freevars_seen: NodeMap(),
1276             export_map: NodeMap(),
1277             trait_map: NodeMap(),
1278             used_imports: HashSet::new(),
1279             used_crates: HashSet::new(),
1280             external_exports: DefIdSet(),
1281
1282             emit_errors: true,
1283             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1284             glob_map: HashMap::new(),
1285
1286             callback: None,
1287             resolved: false,
1288
1289             arenas: arenas,
1290         }
1291     }
1292
1293     fn arenas() -> ResolverArenas<'a> {
1294         ResolverArenas {
1295             modules: arena::TypedArena::new(),
1296         }
1297     }
1298
1299     fn new_module(&self,
1300                   parent_link: ParentLink<'a>,
1301                   def: Option<Def>,
1302                   external: bool,
1303                   is_public: bool) -> Module<'a> {
1304         self.arenas.modules.alloc(ModuleS::new(parent_link, def, external, is_public))
1305     }
1306
1307     #[inline]
1308     fn record_import_use(&mut self, import_id: NodeId, name: Name) {
1309         if !self.make_glob_map {
1310             return;
1311         }
1312         if self.glob_map.contains_key(&import_id) {
1313             self.glob_map.get_mut(&import_id).unwrap().insert(name);
1314             return;
1315         }
1316
1317         let mut new_set = HashSet::new();
1318         new_set.insert(name);
1319         self.glob_map.insert(import_id, new_set);
1320     }
1321
1322     fn get_trait_name(&self, did: DefId) -> Name {
1323         if let Some(node_id) = self.ast_map.as_local_node_id(did) {
1324             self.ast_map.expect_item(node_id).name
1325         } else {
1326             self.session.cstore.item_name(did)
1327         }
1328     }
1329
1330     /// Check that an external crate doesn't collide with items or other external crates.
1331     fn check_for_conflicts_for_external_crate(&self, module: Module<'a>, name: Name, span: Span) {
1332         if module.external_module_children.borrow().contains_key(&name) {
1333             span_err!(self.session,
1334                       span,
1335                       E0259,
1336                       "an external crate named `{}` has already been imported into this module",
1337                       name);
1338         }
1339         match module.children.borrow().get(&name) {
1340             Some(name_bindings) if name_bindings.type_ns.defined() => {
1341                 resolve_error(self,
1342                               name_bindings.type_ns.span().unwrap_or(codemap::DUMMY_SP),
1343                               ResolutionError::NameConflictsWithExternCrate(name));
1344             }
1345             _ => {},
1346         }
1347     }
1348
1349     /// Checks that the names of items don't collide with external crates.
1350     fn check_for_conflicts_between_external_crates_and_items(&self,
1351                                                              module: Module<'a>,
1352                                                              name: Name,
1353                                                              span: Span) {
1354         if module.external_module_children.borrow().contains_key(&name) {
1355             resolve_error(self, span, ResolutionError::NameConflictsWithExternCrate(name));
1356         }
1357     }
1358
1359     /// Resolves the given module path from the given root `module_`.
1360     fn resolve_module_path_from_root(&mut self,
1361                                      module_: Module<'a>,
1362                                      module_path: &[Name],
1363                                      index: usize,
1364                                      span: Span,
1365                                      name_search_type: NameSearchType,
1366                                      lp: LastPrivate)
1367                                      -> ResolveResult<(Module<'a>, LastPrivate)> {
1368         fn search_parent_externals<'a>(needle: Name, module: Module<'a>)
1369                                        -> Option<Module<'a>> {
1370             match module.external_module_children.borrow().get(&needle) {
1371                 Some(_) => Some(module),
1372                 None => match module.parent_link {
1373                     ModuleParentLink(ref parent, _) => {
1374                         search_parent_externals(needle, parent)
1375                     }
1376                     _ => None,
1377                 },
1378             }
1379         }
1380
1381         let mut search_module = module_;
1382         let mut index = index;
1383         let module_path_len = module_path.len();
1384         let mut closest_private = lp;
1385
1386         // Resolve the module part of the path. This does not involve looking
1387         // upward though scope chains; we simply resolve names directly in
1388         // modules as we go.
1389         while index < module_path_len {
1390             let name = module_path[index];
1391             match self.resolve_name_in_module(search_module,
1392                                               name,
1393                                               TypeNS,
1394                                               name_search_type,
1395                                               false) {
1396                 Failed(None) => {
1397                     let segment_name = name.as_str();
1398                     let module_name = module_to_string(search_module);
1399                     let mut span = span;
1400                     let msg = if "???" == &module_name[..] {
1401                         span.hi = span.lo + Pos::from_usize(segment_name.len());
1402
1403                         match search_parent_externals(name, &self.current_module) {
1404                             Some(module) => {
1405                                 let path_str = names_to_string(module_path);
1406                                 let target_mod_str = module_to_string(&*module);
1407                                 let current_mod_str = module_to_string(&*self.current_module);
1408
1409                                 let prefix = if target_mod_str == current_mod_str {
1410                                     "self::".to_string()
1411                                 } else {
1412                                     format!("{}::", target_mod_str)
1413                                 };
1414
1415                                 format!("Did you mean `{}{}`?", prefix, path_str)
1416                             }
1417                             None => format!("Maybe a missing `extern crate {}`?", segment_name),
1418                         }
1419                     } else {
1420                         format!("Could not find `{}` in `{}`", segment_name, module_name)
1421                     };
1422
1423                     return Failed(Some((span, msg)));
1424                 }
1425                 Failed(err) => return Failed(err),
1426                 Indeterminate => {
1427                     debug!("(resolving module path for import) module resolution is \
1428                             indeterminate: {}",
1429                            name);
1430                     return Indeterminate;
1431                 }
1432                 Success((target, used_proxy)) => {
1433                     // Check to see whether there are type bindings, and, if
1434                     // so, whether there is a module within.
1435                     if let Some(module_def) = target.binding.module() {
1436                         // track extern crates for unused_extern_crate lint
1437                         if let Some(did) = module_def.def_id() {
1438                             self.used_crates.insert(did.krate);
1439                         }
1440
1441                         search_module = module_def;
1442
1443                         // Keep track of the closest private module used
1444                         // when resolving this import chain.
1445                         if !used_proxy && !search_module.is_public {
1446                             if let Some(did) = search_module.def_id() {
1447                                 closest_private = LastMod(DependsOn(did));
1448                             }
1449                         }
1450                     } else {
1451                         let msg = format!("Not a module `{}`", name);
1452                         return Failed(Some((span, msg)));
1453                     }
1454                 }
1455             }
1456
1457             index += 1;
1458         }
1459
1460         return Success((search_module, closest_private));
1461     }
1462
1463     /// Attempts to resolve the module part of an import directive or path
1464     /// rooted at the given module.
1465     ///
1466     /// On success, returns the resolved module, and the closest *private*
1467     /// module found to the destination when resolving this path.
1468     fn resolve_module_path(&mut self,
1469                            module_: Module<'a>,
1470                            module_path: &[Name],
1471                            use_lexical_scope: UseLexicalScopeFlag,
1472                            span: Span,
1473                            name_search_type: NameSearchType)
1474                            -> ResolveResult<(Module<'a>, LastPrivate)> {
1475         let module_path_len = module_path.len();
1476         assert!(module_path_len > 0);
1477
1478         debug!("(resolving module path for import) processing `{}` rooted at `{}`",
1479                names_to_string(module_path),
1480                module_to_string(&*module_));
1481
1482         // Resolve the module prefix, if any.
1483         let module_prefix_result = self.resolve_module_prefix(module_, module_path);
1484
1485         let search_module;
1486         let start_index;
1487         let last_private;
1488         match module_prefix_result {
1489             Failed(None) => {
1490                 let mpath = names_to_string(module_path);
1491                 let mpath = &mpath[..];
1492                 match mpath.rfind(':') {
1493                     Some(idx) => {
1494                         let msg = format!("Could not find `{}` in `{}`",
1495                                           // idx +- 1 to account for the
1496                                           // colons on either side
1497                                           &mpath[idx + 1..],
1498                                           &mpath[..idx - 1]);
1499                         return Failed(Some((span, msg)));
1500                     }
1501                     None => {
1502                         return Failed(None);
1503                     }
1504                 }
1505             }
1506             Failed(err) => return Failed(err),
1507             Indeterminate => {
1508                 debug!("(resolving module path for import) indeterminate; bailing");
1509                 return Indeterminate;
1510             }
1511             Success(NoPrefixFound) => {
1512                 // There was no prefix, so we're considering the first element
1513                 // of the path. How we handle this depends on whether we were
1514                 // instructed to use lexical scope or not.
1515                 match use_lexical_scope {
1516                     DontUseLexicalScope => {
1517                         // This is a crate-relative path. We will start the
1518                         // resolution process at index zero.
1519                         search_module = self.graph_root;
1520                         start_index = 0;
1521                         last_private = LastMod(AllPublic);
1522                     }
1523                     UseLexicalScope => {
1524                         // This is not a crate-relative path. We resolve the
1525                         // first component of the path in the current lexical
1526                         // scope and then proceed to resolve below that.
1527                         match self.resolve_module_in_lexical_scope(module_, module_path[0]) {
1528                             Failed(err) => return Failed(err),
1529                             Indeterminate => {
1530                                 debug!("(resolving module path for import) indeterminate; bailing");
1531                                 return Indeterminate;
1532                             }
1533                             Success(containing_module) => {
1534                                 search_module = containing_module;
1535                                 start_index = 1;
1536                                 last_private = LastMod(AllPublic);
1537                             }
1538                         }
1539                     }
1540                 }
1541             }
1542             Success(PrefixFound(ref containing_module, index)) => {
1543                 search_module = containing_module;
1544                 start_index = index;
1545                 last_private = LastMod(DependsOn(containing_module.def_id()
1546                                                                   .unwrap()));
1547             }
1548         }
1549
1550         self.resolve_module_path_from_root(search_module,
1551                                            module_path,
1552                                            start_index,
1553                                            span,
1554                                            name_search_type,
1555                                            last_private)
1556     }
1557
1558     /// Invariant: This must only be called during main resolution, not during
1559     /// import resolution.
1560     fn resolve_item_in_lexical_scope(&mut self,
1561                                      module_: Module<'a>,
1562                                      name: Name,
1563                                      namespace: Namespace,
1564                                      record_used: bool)
1565                                      -> ResolveResult<(Target<'a>, bool)> {
1566         debug!("(resolving item in lexical scope) resolving `{}` in namespace {:?} in `{}`",
1567                name,
1568                namespace,
1569                module_to_string(&*module_));
1570
1571         // The current module node is handled specially. First, check for
1572         // its immediate children.
1573         build_reduced_graph::populate_module_if_necessary(self, &module_);
1574
1575         match module_.children.borrow().get(&name) {
1576             Some(name_bindings) if name_bindings[namespace].defined() => {
1577                 debug!("top name bindings succeeded");
1578                 return Success((Target::new(module_,
1579                                             name_bindings[namespace].clone(),
1580                                             Shadowable::Never),
1581                                 false));
1582             }
1583             Some(_) | None => {
1584                 // Not found; continue.
1585             }
1586         }
1587
1588         // Now check for its import directives. We don't have to have resolved
1589         // all its imports in the usual way; this is because chains of
1590         // adjacent import statements are processed as though they mutated the
1591         // current scope.
1592         if let Some(import_resolution) = module_.import_resolutions.borrow().get(&name) {
1593             match import_resolution[namespace].target.clone() {
1594                 None => {
1595                     // Not found; continue.
1596                     debug!("(resolving item in lexical scope) found import resolution, but not \
1597                             in namespace {:?}",
1598                            namespace);
1599                 }
1600                 Some(target) => {
1601                     debug!("(resolving item in lexical scope) using import resolution");
1602                     // track used imports and extern crates as well
1603                     let id = import_resolution[namespace].id;
1604                     if record_used {
1605                         self.used_imports.insert((id, namespace));
1606                         self.record_import_use(id, name);
1607                         if let Some(DefId{krate: kid, ..}) = target.target_module.def_id() {
1608                             self.used_crates.insert(kid);
1609                         }
1610                     }
1611                     return Success((target, false));
1612                 }
1613             }
1614         }
1615
1616         // Search for external modules.
1617         if namespace == TypeNS {
1618             let children = module_.external_module_children.borrow();
1619             if let Some(module) = children.get(&name) {
1620                 let name_binding = NameBinding::create_from_module(module);
1621                 debug!("lower name bindings succeeded");
1622                 return Success((Target::new(module_, name_binding, Shadowable::Never),
1623                                 false));
1624             }
1625         }
1626
1627         // Finally, proceed up the scope chain looking for parent modules.
1628         let mut search_module = module_;
1629         loop {
1630             // Go to the next parent.
1631             match search_module.parent_link {
1632                 NoParentLink => {
1633                     // No more parents. This module was unresolved.
1634                     debug!("(resolving item in lexical scope) unresolved module");
1635                     return Failed(None);
1636                 }
1637                 ModuleParentLink(parent_module_node, _) => {
1638                     if search_module.is_normal() {
1639                         // We stop the search here.
1640                         debug!("(resolving item in lexical scope) unresolved module: not \
1641                                 searching through module parents");
1642                             return Failed(None);
1643                     } else {
1644                         search_module = parent_module_node;
1645                     }
1646                 }
1647                 BlockParentLink(parent_module_node, _) => {
1648                     search_module = parent_module_node;
1649                 }
1650             }
1651
1652             // Resolve the name in the parent module.
1653             match self.resolve_name_in_module(search_module,
1654                                               name,
1655                                               namespace,
1656                                               PathSearch,
1657                                               true) {
1658                 Failed(Some((span, msg))) => {
1659                     resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
1660                 }
1661                 Failed(None) => (), // Continue up the search chain.
1662                 Indeterminate => {
1663                     // We couldn't see through the higher scope because of an
1664                     // unresolved import higher up. Bail.
1665
1666                     debug!("(resolving item in lexical scope) indeterminate higher scope; bailing");
1667                     return Indeterminate;
1668                 }
1669                 Success((target, used_reexport)) => {
1670                     // We found the module.
1671                     debug!("(resolving item in lexical scope) found name in module, done");
1672                     return Success((target, used_reexport));
1673                 }
1674             }
1675         }
1676     }
1677
1678     /// Resolves a module name in the current lexical scope.
1679     fn resolve_module_in_lexical_scope(&mut self,
1680                                        module_: Module<'a>,
1681                                        name: Name)
1682                                        -> ResolveResult<Module<'a>> {
1683         // If this module is an anonymous module, resolve the item in the
1684         // lexical scope. Otherwise, resolve the item from the crate root.
1685         let resolve_result = self.resolve_item_in_lexical_scope(module_, name, TypeNS, true);
1686         match resolve_result {
1687             Success((target, _)) => {
1688                 if let Some(module_def) = target.binding.module() {
1689                     return Success(module_def)
1690                 } else {
1691                     debug!("!!! (resolving module in lexical scope) module \
1692                             wasn't actually a module!");
1693                     return Failed(None);
1694                 }
1695             }
1696             Indeterminate => {
1697                 debug!("(resolving module in lexical scope) indeterminate; bailing");
1698                 return Indeterminate;
1699             }
1700             Failed(err) => {
1701                 debug!("(resolving module in lexical scope) failed to resolve");
1702                 return Failed(err);
1703             }
1704         }
1705     }
1706
1707     /// Returns the nearest normal module parent of the given module.
1708     fn get_nearest_normal_module_parent(&mut self, module_: Module<'a>) -> Option<Module<'a>> {
1709         let mut module_ = module_;
1710         loop {
1711             match module_.parent_link {
1712                 NoParentLink => return None,
1713                 ModuleParentLink(new_module, _) |
1714                 BlockParentLink(new_module, _) => {
1715                     let new_module = new_module;
1716                     if new_module.is_normal() {
1717                         return Some(new_module);
1718                     }
1719                     module_ = new_module;
1720                 }
1721             }
1722         }
1723     }
1724
1725     /// Returns the nearest normal module parent of the given module, or the
1726     /// module itself if it is a normal module.
1727     fn get_nearest_normal_module_parent_or_self(&mut self, module_: Module<'a>) -> Module<'a> {
1728         if module_.is_normal() {
1729             return module_;
1730         }
1731         match self.get_nearest_normal_module_parent(module_) {
1732             None => module_,
1733             Some(new_module) => new_module,
1734         }
1735     }
1736
1737     /// Resolves a "module prefix". A module prefix is one or both of (a) `self::`;
1738     /// (b) some chain of `super::`.
1739     /// grammar: (SELF MOD_SEP ) ? (SUPER MOD_SEP) *
1740     fn resolve_module_prefix(&mut self,
1741                              module_: Module<'a>,
1742                              module_path: &[Name])
1743                              -> ResolveResult<ModulePrefixResult<'a>> {
1744         // Start at the current module if we see `self` or `super`, or at the
1745         // top of the crate otherwise.
1746         let mut i = match &*module_path[0].as_str() {
1747             "self" => 1,
1748             "super" => 0,
1749             _ => return Success(NoPrefixFound),
1750         };
1751         let mut containing_module = self.get_nearest_normal_module_parent_or_self(module_);
1752
1753         // Now loop through all the `super`s we find.
1754         while i < module_path.len() && "super" == module_path[i].as_str() {
1755             debug!("(resolving module prefix) resolving `super` at {}",
1756                    module_to_string(&*containing_module));
1757             match self.get_nearest_normal_module_parent(containing_module) {
1758                 None => return Failed(None),
1759                 Some(new_module) => {
1760                     containing_module = new_module;
1761                     i += 1;
1762                 }
1763             }
1764         }
1765
1766         debug!("(resolving module prefix) finished resolving prefix at {}",
1767                module_to_string(&*containing_module));
1768
1769         return Success(PrefixFound(containing_module, i));
1770     }
1771
1772     /// Attempts to resolve the supplied name in the given module for the
1773     /// given namespace. If successful, returns the target corresponding to
1774     /// the name.
1775     ///
1776     /// The boolean returned on success is an indicator of whether this lookup
1777     /// passed through a public re-export proxy.
1778     fn resolve_name_in_module(&mut self,
1779                               module_: Module<'a>,
1780                               name: Name,
1781                               namespace: Namespace,
1782                               name_search_type: NameSearchType,
1783                               allow_private_imports: bool)
1784                               -> ResolveResult<(Target<'a>, bool)> {
1785         debug!("(resolving name in module) resolving `{}` in `{}`",
1786                name,
1787                module_to_string(&*module_));
1788
1789         // First, check the direct children of the module.
1790         build_reduced_graph::populate_module_if_necessary(self, &module_);
1791
1792         let children = module_.children.borrow();
1793         match children.get(&name) {
1794             Some(name_bindings) if name_bindings[namespace].defined() => {
1795                 debug!("(resolving name in module) found node as child");
1796                 return Success((Target::new(module_,
1797                                             name_bindings[namespace].clone(),
1798                                             Shadowable::Never),
1799                                 false));
1800             }
1801             Some(_) | None => {
1802                 // Continue.
1803             }
1804         }
1805
1806         // Next, check the module's imports if necessary.
1807
1808         // If this is a search of all imports, we should be done with glob
1809         // resolution at this point.
1810         if name_search_type == PathSearch {
1811             assert_eq!(module_.glob_count.get(), 0);
1812         }
1813
1814         // Check the list of resolved imports.
1815         let children = module_.import_resolutions.borrow();
1816         match children.get(&name) {
1817             Some(import_resolution) if allow_private_imports ||
1818                                        import_resolution[namespace].is_public => {
1819
1820                 if import_resolution[namespace].is_public &&
1821                    import_resolution.outstanding_references != 0 {
1822                     debug!("(resolving name in module) import unresolved; bailing out");
1823                     return Indeterminate;
1824                 }
1825                 match import_resolution[namespace].target.clone() {
1826                     None => {
1827                         debug!("(resolving name in module) name found, but not in namespace {:?}",
1828                                namespace);
1829                     }
1830                     Some(target) => {
1831                         debug!("(resolving name in module) resolved to import");
1832                         // track used imports and extern crates as well
1833                         let id = import_resolution[namespace].id;
1834                         self.used_imports.insert((id, namespace));
1835                         self.record_import_use(id, name);
1836                         if let Some(DefId{krate: kid, ..}) = target.target_module.def_id() {
1837                             self.used_crates.insert(kid);
1838                         }
1839                         return Success((target, true));
1840                     }
1841                 }
1842             }
1843             Some(..) | None => {} // Continue.
1844         }
1845
1846         // Finally, search through external children.
1847         if namespace == TypeNS {
1848             let children = module_.external_module_children.borrow();
1849             if let Some(module) = children.get(&name) {
1850                 let name_binding = NameBinding::create_from_module(module);
1851                 return Success((Target::new(module_, name_binding, Shadowable::Never),
1852                                 false));
1853             }
1854         }
1855
1856         // We're out of luck.
1857         debug!("(resolving name in module) failed to resolve `{}`", name);
1858         return Failed(None);
1859     }
1860
1861     fn report_unresolved_imports(&mut self, module_: Module<'a>) {
1862         let index = module_.resolved_import_count.get();
1863         let imports = module_.imports.borrow();
1864         let import_count = imports.len();
1865         if index != import_count {
1866             resolve_error(self,
1867                           (*imports)[index].span,
1868                           ResolutionError::UnresolvedImport(None));
1869         }
1870
1871         // Descend into children and anonymous children.
1872         build_reduced_graph::populate_module_if_necessary(self, &module_);
1873
1874         for (_, child_node) in module_.children.borrow().iter() {
1875             match child_node.type_ns.module() {
1876                 None => {
1877                     // Continue.
1878                 }
1879                 Some(child_module) => {
1880                     self.report_unresolved_imports(child_module);
1881                 }
1882             }
1883         }
1884
1885         for (_, module_) in module_.anonymous_children.borrow().iter() {
1886             self.report_unresolved_imports(module_);
1887         }
1888     }
1889
1890     // AST resolution
1891     //
1892     // We maintain a list of value ribs and type ribs.
1893     //
1894     // Simultaneously, we keep track of the current position in the module
1895     // graph in the `current_module` pointer. When we go to resolve a name in
1896     // the value or type namespaces, we first look through all the ribs and
1897     // then query the module graph. When we resolve a name in the module
1898     // namespace, we can skip all the ribs (since nested modules are not
1899     // allowed within blocks in Rust) and jump straight to the current module
1900     // graph node.
1901     //
1902     // Named implementations are handled separately. When we find a method
1903     // call, we consult the module node to find all of the implementations in
1904     // scope. This information is lazily cached in the module node. We then
1905     // generate a fake "implementation scope" containing all the
1906     // implementations thus found, for compatibility with old resolve pass.
1907
1908     fn with_scope<F>(&mut self, name: Option<Name>, f: F)
1909         where F: FnOnce(&mut Resolver)
1910     {
1911         let orig_module = self.current_module;
1912
1913         // Move down in the graph.
1914         match name {
1915             None => {
1916                 // Nothing to do.
1917             }
1918             Some(name) => {
1919                 build_reduced_graph::populate_module_if_necessary(self, &orig_module);
1920
1921                 match orig_module.children.borrow().get(&name) {
1922                     None => {
1923                         debug!("!!! (with scope) didn't find `{}` in `{}`",
1924                                name,
1925                                module_to_string(&*orig_module));
1926                     }
1927                     Some(name_bindings) => {
1928                         match name_bindings.type_ns.module() {
1929                             None => {
1930                                 debug!("!!! (with scope) didn't find module for `{}` in `{}`",
1931                                        name,
1932                                        module_to_string(&*orig_module));
1933                             }
1934                             Some(module_) => {
1935                                 self.current_module = module_;
1936                             }
1937                         }
1938                     }
1939                 }
1940             }
1941         }
1942
1943         f(self);
1944
1945         self.current_module = orig_module;
1946     }
1947
1948     /// Searches the current set of local scopes for labels.
1949     /// Stops after meeting a closure.
1950     fn search_label(&self, name: Name) -> Option<DefLike> {
1951         for rib in self.label_ribs.iter().rev() {
1952             match rib.kind {
1953                 NormalRibKind => {
1954                     // Continue
1955                 }
1956                 _ => {
1957                     // Do not resolve labels across function boundary
1958                     return None;
1959                 }
1960             }
1961             let result = rib.bindings.get(&name).cloned();
1962             if result.is_some() {
1963                 return result;
1964             }
1965         }
1966         None
1967     }
1968
1969     fn resolve_crate(&mut self, krate: &hir::Crate) {
1970         debug!("(resolving crate) starting");
1971
1972         intravisit::walk_crate(self, krate);
1973     }
1974
1975     fn check_if_primitive_type_name(&self, name: Name, span: Span) {
1976         if let Some(_) = self.primitive_type_table.primitive_types.get(&name) {
1977             span_err!(self.session,
1978                       span,
1979                       E0317,
1980                       "user-defined types or type parameters cannot shadow the primitive types");
1981         }
1982     }
1983
1984     fn resolve_item(&mut self, item: &Item) {
1985         let name = item.name;
1986
1987         debug!("(resolving item) resolving {}", name);
1988
1989         match item.node {
1990             ItemEnum(_, ref generics) |
1991             ItemTy(_, ref generics) |
1992             ItemStruct(_, ref generics) => {
1993                 self.check_if_primitive_type_name(name, item.span);
1994
1995                 self.with_type_parameter_rib(HasTypeParameters(generics, TypeSpace, ItemRibKind),
1996                                              |this| intravisit::walk_item(this, item));
1997             }
1998             ItemFn(_, _, _, _, ref generics, _) => {
1999                 self.with_type_parameter_rib(HasTypeParameters(generics, FnSpace, ItemRibKind),
2000                                              |this| intravisit::walk_item(this, item));
2001             }
2002
2003             ItemDefaultImpl(_, ref trait_ref) => {
2004                 self.with_optional_trait_ref(Some(trait_ref), |_, _| {});
2005             }
2006             ItemImpl(_, _, ref generics, ref opt_trait_ref, ref self_type, ref impl_items) => {
2007                 self.resolve_implementation(generics,
2008                                             opt_trait_ref,
2009                                             &**self_type,
2010                                             item.id,
2011                                             impl_items);
2012             }
2013
2014             ItemTrait(_, ref generics, ref bounds, ref trait_items) => {
2015                 self.check_if_primitive_type_name(name, item.span);
2016
2017                 // Create a new rib for the trait-wide type parameters.
2018                 self.with_type_parameter_rib(HasTypeParameters(generics,
2019                                                                TypeSpace,
2020                                                                ItemRibKind),
2021                                              |this| {
2022                     let local_def_id = this.ast_map.local_def_id(item.id);
2023                     this.with_self_rib(DefSelfTy(Some(local_def_id), None), |this| {
2024                         this.visit_generics(generics);
2025                         walk_list!(this, visit_ty_param_bound, bounds);
2026
2027                         for trait_item in trait_items {
2028                             match trait_item.node {
2029                                 hir::ConstTraitItem(_, ref default) => {
2030                                     // Only impose the restrictions of
2031                                     // ConstRibKind if there's an actual constant
2032                                     // expression in a provided default.
2033                                     if default.is_some() {
2034                                         this.with_constant_rib(|this| {
2035                                             intravisit::walk_trait_item(this, trait_item)
2036                                         });
2037                                     } else {
2038                                         intravisit::walk_trait_item(this, trait_item)
2039                                     }
2040                                 }
2041                                 hir::MethodTraitItem(ref sig, _) => {
2042                                     let type_parameters =
2043                                         HasTypeParameters(&sig.generics,
2044                                                           FnSpace,
2045                                                           MethodRibKind);
2046                                     this.with_type_parameter_rib(type_parameters, |this| {
2047                                         intravisit::walk_trait_item(this, trait_item)
2048                                     });
2049                                 }
2050                                 hir::TypeTraitItem(..) => {
2051                                     this.check_if_primitive_type_name(trait_item.name,
2052                                                                       trait_item.span);
2053                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
2054                                         intravisit::walk_trait_item(this, trait_item)
2055                                     });
2056                                 }
2057                             };
2058                         }
2059                     });
2060                 });
2061             }
2062
2063             ItemMod(_) | ItemForeignMod(_) => {
2064                 self.with_scope(Some(name), |this| {
2065                     intravisit::walk_item(this, item);
2066                 });
2067             }
2068
2069             ItemConst(..) | ItemStatic(..) => {
2070                 self.with_constant_rib(|this| {
2071                     intravisit::walk_item(this, item);
2072                 });
2073             }
2074
2075             ItemUse(ref view_path) => {
2076                 // check for imports shadowing primitive types
2077                 let check_rename = |this: &Self, id, name| {
2078                     match this.def_map.borrow().get(&id).map(|d| d.full_def()) {
2079                         Some(DefTy(..)) | Some(DefStruct(..)) | Some(DefTrait(..)) | None => {
2080                             this.check_if_primitive_type_name(name, item.span);
2081                         }
2082                         _ => {}
2083                     }
2084                 };
2085
2086                 match view_path.node {
2087                     hir::ViewPathSimple(name, _) => {
2088                         check_rename(self, item.id, name);
2089                     }
2090                     hir::ViewPathList(ref prefix, ref items) => {
2091                         for item in items {
2092                             if let Some(name) = item.node.rename() {
2093                                 check_rename(self, item.node.id(), name);
2094                             }
2095                         }
2096
2097                         // Resolve prefix of an import with empty braces (issue #28388)
2098                         if items.is_empty() && !prefix.segments.is_empty() {
2099                             match self.resolve_crate_relative_path(prefix.span,
2100                                                                    &prefix.segments,
2101                                                                    TypeNS) {
2102                                 Some((def, lp)) =>
2103                                     self.record_def(item.id, PathResolution::new(def, lp, 0)),
2104                                 None => {
2105                                     resolve_error(self,
2106                                                   prefix.span,
2107                                                   ResolutionError::FailedToResolve(
2108                                                       &path_names_to_string(prefix, 0)));
2109                                     self.record_def(item.id, err_path_resolution());
2110                                 }
2111                             }
2112                         }
2113                     }
2114                     _ => {}
2115                 }
2116             }
2117
2118             ItemExternCrate(_) => {
2119                 // do nothing, these are just around to be encoded
2120             }
2121         }
2122     }
2123
2124     fn with_type_parameter_rib<F>(&mut self, type_parameters: TypeParameters, f: F)
2125         where F: FnOnce(&mut Resolver)
2126     {
2127         match type_parameters {
2128             HasTypeParameters(generics, space, rib_kind) => {
2129                 let mut function_type_rib = Rib::new(rib_kind);
2130                 let mut seen_bindings = HashSet::new();
2131                 for (index, type_parameter) in generics.ty_params.iter().enumerate() {
2132                     let name = type_parameter.name;
2133                     debug!("with_type_parameter_rib: {}", type_parameter.id);
2134
2135                     if seen_bindings.contains(&name) {
2136                         resolve_error(self,
2137                                       type_parameter.span,
2138                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name));
2139                     }
2140                     seen_bindings.insert(name);
2141
2142                     // plain insert (no renaming)
2143                     function_type_rib.bindings
2144                                      .insert(name,
2145                                              DlDef(DefTyParam(space,
2146                                                               index as u32,
2147                                                               self.ast_map
2148                                                                   .local_def_id(type_parameter.id),
2149                                                               name)));
2150                 }
2151                 self.type_ribs.push(function_type_rib);
2152             }
2153
2154             NoTypeParameters => {
2155                 // Nothing to do.
2156             }
2157         }
2158
2159         f(self);
2160
2161         match type_parameters {
2162             HasTypeParameters(..) => {
2163                 if !self.resolved {
2164                     self.type_ribs.pop();
2165                 }
2166             }
2167             NoTypeParameters => {}
2168         }
2169     }
2170
2171     fn with_label_rib<F>(&mut self, f: F)
2172         where F: FnOnce(&mut Resolver)
2173     {
2174         self.label_ribs.push(Rib::new(NormalRibKind));
2175         f(self);
2176         if !self.resolved {
2177             self.label_ribs.pop();
2178         }
2179     }
2180
2181     fn with_constant_rib<F>(&mut self, f: F)
2182         where F: FnOnce(&mut Resolver)
2183     {
2184         self.value_ribs.push(Rib::new(ConstantItemRibKind));
2185         self.type_ribs.push(Rib::new(ConstantItemRibKind));
2186         f(self);
2187         if !self.resolved {
2188             self.type_ribs.pop();
2189             self.value_ribs.pop();
2190         }
2191     }
2192
2193     fn resolve_function(&mut self, rib_kind: RibKind, declaration: &FnDecl, block: &Block) {
2194         // Create a value rib for the function.
2195         self.value_ribs.push(Rib::new(rib_kind));
2196
2197         // Create a label rib for the function.
2198         self.label_ribs.push(Rib::new(rib_kind));
2199
2200         // Add each argument to the rib.
2201         let mut bindings_list = HashMap::new();
2202         for argument in &declaration.inputs {
2203             self.resolve_pattern(&*argument.pat, ArgumentIrrefutableMode, &mut bindings_list);
2204
2205             self.visit_ty(&*argument.ty);
2206
2207             debug!("(resolving function) recorded argument");
2208         }
2209         intravisit::walk_fn_ret_ty(self, &declaration.output);
2210
2211         // Resolve the function body.
2212         self.visit_block(block);
2213
2214         debug!("(resolving function) leaving function");
2215
2216         if !self.resolved {
2217             self.label_ribs.pop();
2218             self.value_ribs.pop();
2219         }
2220     }
2221
2222     fn resolve_trait_reference(&mut self,
2223                                id: NodeId,
2224                                trait_path: &Path,
2225                                path_depth: usize)
2226                                -> Result<PathResolution, ()> {
2227         if let Some(path_res) = self.resolve_path(id, trait_path, path_depth, TypeNS, true) {
2228             if let DefTrait(_) = path_res.base_def {
2229                 debug!("(resolving trait) found trait def: {:?}", path_res);
2230                 Ok(path_res)
2231             } else {
2232                 let mut err =
2233                     resolve_struct_error(self,
2234                                   trait_path.span,
2235                                   ResolutionError::IsNotATrait(&*path_names_to_string(trait_path,
2236                                                                                       path_depth)));
2237
2238                 // If it's a typedef, give a note
2239                 if let DefTy(..) = path_res.base_def {
2240                     err.span_note(trait_path.span,
2241                                   "`type` aliases cannot be used for traits");
2242                 }
2243                 err.emit();
2244                 Err(())
2245             }
2246         } else {
2247             resolve_error(self,
2248                           trait_path.span,
2249                           ResolutionError::UndeclaredTraitName(&*path_names_to_string(trait_path,
2250                                                                                       path_depth)));
2251             Err(())
2252         }
2253     }
2254
2255     fn resolve_generics(&mut self, generics: &Generics) {
2256         for type_parameter in generics.ty_params.iter() {
2257             self.check_if_primitive_type_name(type_parameter.name, type_parameter.span);
2258         }
2259         for predicate in &generics.where_clause.predicates {
2260             match predicate {
2261                 &hir::WherePredicate::BoundPredicate(_) |
2262                 &hir::WherePredicate::RegionPredicate(_) => {}
2263                 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
2264                     let path_res = self.resolve_path(eq_pred.id, &eq_pred.path, 0, TypeNS, true);
2265                     if let Some(PathResolution { base_def: DefTyParam(..), .. }) = path_res {
2266                         self.record_def(eq_pred.id, path_res.unwrap());
2267                     } else {
2268                         resolve_error(self,
2269                                       eq_pred.span,
2270                                       ResolutionError::UndeclaredAssociatedType);
2271                         self.record_def(eq_pred.id, err_path_resolution());
2272                     }
2273                 }
2274             }
2275         }
2276         intravisit::walk_generics(self, generics);
2277     }
2278
2279     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
2280         where F: FnOnce(&mut Resolver) -> T
2281     {
2282         // Handle nested impls (inside fn bodies)
2283         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
2284         let result = f(self);
2285         self.current_self_type = previous_value;
2286         result
2287     }
2288
2289     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
2290         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
2291     {
2292         let mut new_val = None;
2293         let mut new_id = None;
2294         if let Some(trait_ref) = opt_trait_ref {
2295             if let Ok(path_res) = self.resolve_trait_reference(trait_ref.ref_id,
2296                                                                &trait_ref.path,
2297                                                                0) {
2298                 assert!(path_res.depth == 0);
2299                 self.record_def(trait_ref.ref_id, path_res);
2300                 new_val = Some((path_res.base_def.def_id(), trait_ref.clone()));
2301                 new_id = Some(path_res.base_def.def_id());
2302             } else {
2303                 self.record_def(trait_ref.ref_id, err_path_resolution());
2304             }
2305             intravisit::walk_trait_ref(self, trait_ref);
2306         }
2307         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2308         let result = f(self, new_id);
2309         self.current_trait_ref = original_trait_ref;
2310         result
2311     }
2312
2313     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
2314         where F: FnOnce(&mut Resolver)
2315     {
2316         let mut self_type_rib = Rib::new(NormalRibKind);
2317
2318         // plain insert (no renaming, types are not currently hygienic....)
2319         let name = special_names::type_self;
2320         self_type_rib.bindings.insert(name, DlDef(self_def));
2321         self.type_ribs.push(self_type_rib);
2322         f(self);
2323         if !self.resolved {
2324             self.type_ribs.pop();
2325         }
2326     }
2327
2328     fn resolve_implementation(&mut self,
2329                               generics: &Generics,
2330                               opt_trait_reference: &Option<TraitRef>,
2331                               self_type: &Ty,
2332                               item_id: NodeId,
2333                               impl_items: &[ImplItem]) {
2334         // If applicable, create a rib for the type parameters.
2335         self.with_type_parameter_rib(HasTypeParameters(generics,
2336                                                        TypeSpace,
2337                                                        ItemRibKind),
2338                                      |this| {
2339             // Resolve the type parameters.
2340             this.visit_generics(generics);
2341
2342             // Resolve the trait reference, if necessary.
2343             this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2344                 // Resolve the self type.
2345                 this.visit_ty(self_type);
2346
2347                 this.with_self_rib(DefSelfTy(trait_id, Some((item_id, self_type.id))), |this| {
2348                     this.with_current_self_type(self_type, |this| {
2349                         for impl_item in impl_items {
2350                             match impl_item.node {
2351                                 hir::ImplItemKind::Const(..) => {
2352                                     // If this is a trait impl, ensure the const
2353                                     // exists in trait
2354                                     this.check_trait_item(impl_item.name,
2355                                                           impl_item.span,
2356                                         |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
2357                                     this.with_constant_rib(|this| {
2358                                         intravisit::walk_impl_item(this, impl_item);
2359                                     });
2360                                 }
2361                                 hir::ImplItemKind::Method(ref sig, _) => {
2362                                     // If this is a trait impl, ensure the method
2363                                     // exists in trait
2364                                     this.check_trait_item(impl_item.name,
2365                                                           impl_item.span,
2366                                         |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
2367
2368                                     // We also need a new scope for the method-
2369                                     // specific type parameters.
2370                                     let type_parameters =
2371                                         HasTypeParameters(&sig.generics,
2372                                                           FnSpace,
2373                                                           MethodRibKind);
2374                                     this.with_type_parameter_rib(type_parameters, |this| {
2375                                         intravisit::walk_impl_item(this, impl_item);
2376                                     });
2377                                 }
2378                                 hir::ImplItemKind::Type(ref ty) => {
2379                                     // If this is a trait impl, ensure the type
2380                                     // exists in trait
2381                                     this.check_trait_item(impl_item.name,
2382                                                           impl_item.span,
2383                                         |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
2384
2385                                     this.visit_ty(ty);
2386                                 }
2387                             }
2388                         }
2389                     });
2390                 });
2391             });
2392         });
2393     }
2394
2395     fn check_trait_item<F>(&self, name: Name, span: Span, err: F)
2396         where F: FnOnce(Name, &str) -> ResolutionError
2397     {
2398         // If there is a TraitRef in scope for an impl, then the method must be in the
2399         // trait.
2400         if let Some((did, ref trait_ref)) = self.current_trait_ref {
2401             if !self.trait_item_map.contains_key(&(name, did)) {
2402                 let path_str = path_names_to_string(&trait_ref.path, 0);
2403                 resolve_error(self, span, err(name, &*path_str));
2404             }
2405         }
2406     }
2407
2408     fn resolve_local(&mut self, local: &Local) {
2409         // Resolve the type.
2410         walk_list!(self, visit_ty, &local.ty);
2411
2412         // Resolve the initializer.
2413         walk_list!(self, visit_expr, &local.init);
2414
2415         // Resolve the pattern.
2416         self.resolve_pattern(&*local.pat, LocalIrrefutableMode, &mut HashMap::new());
2417     }
2418
2419     // build a map from pattern identifiers to binding-info's.
2420     // this is done hygienically. This could arise for a macro
2421     // that expands into an or-pattern where one 'x' was from the
2422     // user and one 'x' came from the macro.
2423     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2424         let mut result = HashMap::new();
2425         pat_bindings(&self.def_map, pat, |binding_mode, _id, sp, path1| {
2426             let name = path1.node;
2427             result.insert(name,
2428                           BindingInfo {
2429                               span: sp,
2430                               binding_mode: binding_mode,
2431                           });
2432         });
2433         return result;
2434     }
2435
2436     // check that all of the arms in an or-pattern have exactly the
2437     // same set of bindings, with the same binding modes for each.
2438     fn check_consistent_bindings(&mut self, arm: &Arm) {
2439         if arm.pats.is_empty() {
2440             return;
2441         }
2442         let map_0 = self.binding_mode_map(&*arm.pats[0]);
2443         for (i, p) in arm.pats.iter().enumerate() {
2444             let map_i = self.binding_mode_map(&**p);
2445
2446             for (&key, &binding_0) in &map_0 {
2447                 match map_i.get(&key) {
2448                     None => {
2449                         resolve_error(self,
2450                                       p.span,
2451                                       ResolutionError::VariableNotBoundInPattern(key, i + 1));
2452                     }
2453                     Some(binding_i) => {
2454                         if binding_0.binding_mode != binding_i.binding_mode {
2455                             resolve_error(self,
2456                                           binding_i.span,
2457                                           ResolutionError::VariableBoundWithDifferentMode(key,
2458                                                                                           i + 1));
2459                         }
2460                     }
2461                 }
2462             }
2463
2464             for (&key, &binding) in &map_i {
2465                 if !map_0.contains_key(&key) {
2466                     resolve_error(self,
2467                                   binding.span,
2468                                   ResolutionError::VariableNotBoundInParentPattern(key, i + 1));
2469                 }
2470             }
2471         }
2472     }
2473
2474     fn resolve_arm(&mut self, arm: &Arm) {
2475         self.value_ribs.push(Rib::new(NormalRibKind));
2476
2477         let mut bindings_list = HashMap::new();
2478         for pattern in &arm.pats {
2479             self.resolve_pattern(&**pattern, RefutableMode, &mut bindings_list);
2480         }
2481
2482         // This has to happen *after* we determine which
2483         // pat_idents are variants
2484         self.check_consistent_bindings(arm);
2485
2486         walk_list!(self, visit_expr, &arm.guard);
2487         self.visit_expr(&*arm.body);
2488
2489         if !self.resolved {
2490             self.value_ribs.pop();
2491         }
2492     }
2493
2494     fn resolve_block(&mut self, block: &Block) {
2495         debug!("(resolving block) entering block");
2496         self.value_ribs.push(Rib::new(NormalRibKind));
2497
2498         // Move down in the graph, if there's an anonymous module rooted here.
2499         let orig_module = self.current_module;
2500         match orig_module.anonymous_children.borrow().get(&block.id) {
2501             None => {
2502                 // Nothing to do.
2503             }
2504             Some(anonymous_module) => {
2505                 debug!("(resolving block) found anonymous module, moving down");
2506                 self.current_module = anonymous_module;
2507             }
2508         }
2509
2510         // Check for imports appearing after non-item statements.
2511         let mut found_non_item = false;
2512         for statement in &block.stmts {
2513             if let hir::StmtDecl(ref declaration, _) = statement.node {
2514                 if let hir::DeclItem(i) = declaration.node {
2515                     let i = self.ast_map.expect_item(i.id);
2516                     match i.node {
2517                         ItemExternCrate(_) | ItemUse(_) if found_non_item => {
2518                             span_err!(self.session,
2519                                       i.span,
2520                                       E0154,
2521                                       "imports are not allowed after non-item statements");
2522                         }
2523                         _ => {}
2524                     }
2525                 } else {
2526                     found_non_item = true
2527                 }
2528             } else {
2529                 found_non_item = true;
2530             }
2531         }
2532
2533         // Descend into the block.
2534         intravisit::walk_block(self, block);
2535
2536         // Move back up.
2537         if !self.resolved {
2538             self.current_module = orig_module;
2539             self.value_ribs.pop();
2540         }
2541         debug!("(resolving block) leaving block");
2542     }
2543
2544     fn resolve_type(&mut self, ty: &Ty) {
2545         match ty.node {
2546             TyPath(ref maybe_qself, ref path) => {
2547                 let resolution = match self.resolve_possibly_assoc_item(ty.id,
2548                                                                         maybe_qself.as_ref(),
2549                                                                         path,
2550                                                                         TypeNS,
2551                                                                         true) {
2552                     // `<T>::a::b::c` is resolved by typeck alone.
2553                     TypecheckRequired => {
2554                         // Resolve embedded types.
2555                         intravisit::walk_ty(self, ty);
2556                         return;
2557                     }
2558                     ResolveAttempt(resolution) => resolution,
2559                 };
2560
2561                 // This is a path in the type namespace. Walk through scopes
2562                 // looking for it.
2563                 match resolution {
2564                     Some(def) => {
2565                         // Write the result into the def map.
2566                         debug!("(resolving type) writing resolution for `{}` (id {}) = {:?}",
2567                                path_names_to_string(path, 0),
2568                                ty.id,
2569                                def);
2570                         self.record_def(ty.id, def);
2571                     }
2572                     None => {
2573                         self.record_def(ty.id, err_path_resolution());
2574
2575                         // Keep reporting some errors even if they're ignored above.
2576                         self.resolve_path(ty.id, path, 0, TypeNS, true);
2577
2578                         let kind = if maybe_qself.is_some() {
2579                             "associated type"
2580                         } else {
2581                             "type name"
2582                         };
2583
2584                         let self_type_name = special_idents::type_self.name;
2585                         let is_invalid_self_type_name = path.segments.len() > 0 &&
2586                                                         maybe_qself.is_none() &&
2587                                                         path.segments[0].identifier.name ==
2588                                                         self_type_name;
2589                         if is_invalid_self_type_name {
2590                             resolve_error(self,
2591                                           ty.span,
2592                                           ResolutionError::SelfUsedOutsideImplOrTrait);
2593                         } else {
2594                             resolve_error(self,
2595                                           ty.span,
2596                                           ResolutionError::UseOfUndeclared(
2597                                                                     kind,
2598                                                                     &*path_names_to_string(path,
2599                                                                                            0))
2600                                          );
2601                         }
2602                     }
2603                 }
2604             }
2605             _ => {}
2606         }
2607         // Resolve embedded types.
2608         intravisit::walk_ty(self, ty);
2609     }
2610
2611     fn resolve_pattern(&mut self,
2612                        pattern: &Pat,
2613                        mode: PatternBindingMode,
2614                        // Maps idents to the node ID for the (outermost)
2615                        // pattern that binds them
2616                        bindings_list: &mut HashMap<Name, NodeId>) {
2617         let pat_id = pattern.id;
2618         walk_pat(pattern, |pattern| {
2619             match pattern.node {
2620                 PatIdent(binding_mode, ref path1, ref at_rhs) => {
2621                     // The meaning of PatIdent with no type parameters
2622                     // depends on whether an enum variant or unit-like struct
2623                     // with that name is in scope. The probing lookup has to
2624                     // be careful not to emit spurious errors. Only matching
2625                     // patterns (match) can match nullary variants or
2626                     // unit-like structs. For binding patterns (let
2627                     // and the LHS of @-patterns), matching such a value is
2628                     // simply disallowed (since it's rarely what you want).
2629                     let const_ok = mode == RefutableMode && at_rhs.is_none();
2630
2631                     let ident = path1.node;
2632                     let renamed = ident.name;
2633
2634                     match self.resolve_bare_identifier_pattern(ident.unhygienic_name,
2635                                                                pattern.span) {
2636                         FoundStructOrEnumVariant(def, lp) if const_ok => {
2637                             debug!("(resolving pattern) resolving `{}` to struct or enum variant",
2638                                    renamed);
2639
2640                             self.enforce_default_binding_mode(pattern,
2641                                                               binding_mode,
2642                                                               "an enum variant");
2643                             self.record_def(pattern.id,
2644                                             PathResolution {
2645                                                 base_def: def,
2646                                                 last_private: lp,
2647                                                 depth: 0,
2648                                             });
2649                         }
2650                         FoundStructOrEnumVariant(..) => {
2651                             resolve_error(
2652                                 self,
2653                                 pattern.span,
2654                                 ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(
2655                                     renamed)
2656                             );
2657                             self.record_def(pattern.id, err_path_resolution());
2658                         }
2659                         FoundConst(def, lp, _) if const_ok => {
2660                             debug!("(resolving pattern) resolving `{}` to constant", renamed);
2661
2662                             self.enforce_default_binding_mode(pattern, binding_mode, "a constant");
2663                             self.record_def(pattern.id,
2664                                             PathResolution {
2665                                                 base_def: def,
2666                                                 last_private: lp,
2667                                                 depth: 0,
2668                                             });
2669                         }
2670                         FoundConst(def, _, name) => {
2671                             resolve_error(
2672                                 self,
2673                                 pattern.span,
2674                                 ResolutionError::OnlyIrrefutablePatternsAllowedHere(def.def_id(),
2675                                                                                     name)
2676                             );
2677                             self.record_def(pattern.id, err_path_resolution());
2678                         }
2679                         BareIdentifierPatternUnresolved => {
2680                             debug!("(resolving pattern) binding `{}`", renamed);
2681
2682                             let def_id = self.ast_map.local_def_id(pattern.id);
2683                             let def = DefLocal(def_id, pattern.id);
2684
2685                             // Record the definition so that later passes
2686                             // will be able to distinguish variants from
2687                             // locals in patterns.
2688
2689                             self.record_def(pattern.id,
2690                                             PathResolution {
2691                                                 base_def: def,
2692                                                 last_private: LastMod(AllPublic),
2693                                                 depth: 0,
2694                                             });
2695
2696                             // Add the binding to the local ribs, if it
2697                             // doesn't already exist in the bindings list. (We
2698                             // must not add it if it's in the bindings list
2699                             // because that breaks the assumptions later
2700                             // passes make about or-patterns.)
2701                             if !bindings_list.contains_key(&renamed) {
2702                                 let this = &mut *self;
2703                                 let last_rib = this.value_ribs.last_mut().unwrap();
2704                                 last_rib.bindings.insert(renamed, DlDef(def));
2705                                 bindings_list.insert(renamed, pat_id);
2706                             } else if mode == ArgumentIrrefutableMode &&
2707                                bindings_list.contains_key(&renamed) {
2708                                 // Forbid duplicate bindings in the same
2709                                 // parameter list.
2710                                 resolve_error(
2711                                     self,
2712                                     pattern.span,
2713                                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2714                                         &ident.name.as_str())
2715                                 );
2716                             } else if bindings_list.get(&renamed) == Some(&pat_id) {
2717                                 // Then this is a duplicate variable in the
2718                                 // same disjunction, which is an error.
2719                                 resolve_error(
2720                                     self,
2721                                     pattern.span,
2722                                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2723                                         &ident.name.as_str())
2724                                 );
2725                             }
2726                             // Else, not bound in the same pattern: do
2727                             // nothing.
2728                         }
2729                     }
2730                 }
2731
2732                 PatEnum(ref path, _) => {
2733                     // This must be an enum variant, struct or const.
2734                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2735                                                                             None,
2736                                                                             path,
2737                                                                             ValueNS,
2738                                                                             false) {
2739                         // The below shouldn't happen because all
2740                         // qualified paths should be in PatQPath.
2741                         TypecheckRequired =>
2742                             self.session.span_bug(path.span,
2743                                                   "resolve_possibly_assoc_item claimed
2744                                      \
2745                                                    that a path in PatEnum requires typecheck
2746                                      \
2747                                                    to resolve, but qualified paths should be
2748                                      \
2749                                                    PatQPath"),
2750                         ResolveAttempt(resolution) => resolution,
2751                     };
2752                     if let Some(path_res) = resolution {
2753                         match path_res.base_def {
2754                             DefVariant(..) | DefStruct(..) | DefConst(..) => {
2755                                 self.record_def(pattern.id, path_res);
2756                             }
2757                             DefStatic(..) => {
2758                                 resolve_error(&self,
2759                                               path.span,
2760                                               ResolutionError::StaticVariableReference);
2761                                 self.record_def(pattern.id, err_path_resolution());
2762                             }
2763                             _ => {
2764                                 // If anything ends up here entirely resolved,
2765                                 // it's an error. If anything ends up here
2766                                 // partially resolved, that's OK, because it may
2767                                 // be a `T::CONST` that typeck will resolve.
2768                                 if path_res.depth == 0 {
2769                                     resolve_error(
2770                                         self,
2771                                         path.span,
2772                                         ResolutionError::NotAnEnumVariantStructOrConst(
2773                                             &path.segments
2774                                                  .last()
2775                                                  .unwrap()
2776                                                  .identifier
2777                                                  .name
2778                                                  .as_str())
2779                                     );
2780                                     self.record_def(pattern.id, err_path_resolution());
2781                                 } else {
2782                                     let const_name = path.segments
2783                                                          .last()
2784                                                          .unwrap()
2785                                                          .identifier
2786                                                          .name;
2787                                     let traits = self.get_traits_containing_item(const_name);
2788                                     self.trait_map.insert(pattern.id, traits);
2789                                     self.record_def(pattern.id, path_res);
2790                                 }
2791                             }
2792                         }
2793                     } else {
2794                         resolve_error(
2795                             self,
2796                             path.span,
2797                             ResolutionError::UnresolvedEnumVariantStructOrConst(
2798                                 &path.segments.last().unwrap().identifier.name.as_str())
2799                         );
2800                         self.record_def(pattern.id, err_path_resolution());
2801                     }
2802                     intravisit::walk_path(self, path);
2803                 }
2804
2805                 PatQPath(ref qself, ref path) => {
2806                     // Associated constants only.
2807                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2808                                                                             Some(qself),
2809                                                                             path,
2810                                                                             ValueNS,
2811                                                                             false) {
2812                         TypecheckRequired => {
2813                             // All `<T>::CONST` should end up here, and will
2814                             // require use of the trait map to resolve
2815                             // during typechecking.
2816                             let const_name = path.segments
2817                                                  .last()
2818                                                  .unwrap()
2819                                                  .identifier
2820                                                  .name;
2821                             let traits = self.get_traits_containing_item(const_name);
2822                             self.trait_map.insert(pattern.id, traits);
2823                             intravisit::walk_pat(self, pattern);
2824                             return true;
2825                         }
2826                         ResolveAttempt(resolution) => resolution,
2827                     };
2828                     if let Some(path_res) = resolution {
2829                         match path_res.base_def {
2830                             // All `<T as Trait>::CONST` should end up here, and
2831                             // have the trait already selected.
2832                             DefAssociatedConst(..) => {
2833                                 self.record_def(pattern.id, path_res);
2834                             }
2835                             _ => {
2836                                 resolve_error(
2837                                     self,
2838                                     path.span,
2839                                     ResolutionError::NotAnAssociatedConst(
2840                                         &path.segments.last().unwrap().identifier.name.as_str()
2841                                     )
2842                                 );
2843                                 self.record_def(pattern.id, err_path_resolution());
2844                             }
2845                         }
2846                     } else {
2847                         resolve_error(self,
2848                                       path.span,
2849                                       ResolutionError::UnresolvedAssociatedConst(&path.segments
2850                                                                                       .last()
2851                                                                                       .unwrap()
2852                                                                                       .identifier
2853                                                                                       .name
2854                                                                                       .as_str()));
2855                         self.record_def(pattern.id, err_path_resolution());
2856                     }
2857                     intravisit::walk_pat(self, pattern);
2858                 }
2859
2860                 PatStruct(ref path, _, _) => {
2861                     match self.resolve_path(pat_id, path, 0, TypeNS, false) {
2862                         Some(definition) => {
2863                             self.record_def(pattern.id, definition);
2864                         }
2865                         result => {
2866                             debug!("(resolving pattern) didn't find struct def: {:?}", result);
2867                             resolve_error(
2868                                 self,
2869                                 path.span,
2870                                 ResolutionError::DoesNotNameAStruct(
2871                                     &*path_names_to_string(path, 0))
2872                             );
2873                             self.record_def(pattern.id, err_path_resolution());
2874                         }
2875                     }
2876                     intravisit::walk_path(self, path);
2877                 }
2878
2879                 PatLit(_) | PatRange(..) => {
2880                     intravisit::walk_pat(self, pattern);
2881                 }
2882
2883                 _ => {
2884                     // Nothing to do.
2885                 }
2886             }
2887             true
2888         });
2889     }
2890
2891     fn resolve_bare_identifier_pattern(&mut self,
2892                                        name: Name,
2893                                        span: Span)
2894                                        -> BareIdentifierPatternResolution {
2895         let module = self.current_module;
2896         match self.resolve_item_in_lexical_scope(module, name, ValueNS, true) {
2897             Success((target, _)) => {
2898                 debug!("(resolve bare identifier pattern) succeeded in finding {} at {:?}",
2899                        name,
2900                        target.binding.borrow());
2901                 match target.binding.def() {
2902                     None => {
2903                         panic!("resolved name in the value namespace to a set of name bindings \
2904                                 with no def?!");
2905                     }
2906                     // For the two success cases, this lookup can be
2907                     // considered as not having a private component because
2908                     // the lookup happened only within the current module.
2909                     Some(def @ DefVariant(..)) | Some(def @ DefStruct(..)) => {
2910                         return FoundStructOrEnumVariant(def, LastMod(AllPublic));
2911                     }
2912                     Some(def @ DefConst(..)) | Some(def @ DefAssociatedConst(..)) => {
2913                         return FoundConst(def, LastMod(AllPublic), name);
2914                     }
2915                     Some(DefStatic(..)) => {
2916                         resolve_error(self, span, ResolutionError::StaticVariableReference);
2917                         return BareIdentifierPatternUnresolved;
2918                     }
2919                     _ => return BareIdentifierPatternUnresolved
2920                 }
2921             }
2922
2923             Indeterminate => {
2924                 panic!("unexpected indeterminate result");
2925             }
2926             Failed(err) => {
2927                 match err {
2928                     Some((span, msg)) => {
2929                         resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
2930                     }
2931                     None => (),
2932                 }
2933
2934                 debug!("(resolve bare identifier pattern) failed to find {}", name);
2935                 return BareIdentifierPatternUnresolved;
2936             }
2937         }
2938     }
2939
2940     /// Handles paths that may refer to associated items
2941     fn resolve_possibly_assoc_item(&mut self,
2942                                    id: NodeId,
2943                                    maybe_qself: Option<&hir::QSelf>,
2944                                    path: &Path,
2945                                    namespace: Namespace,
2946                                    check_ribs: bool)
2947                                    -> AssocItemResolveResult {
2948         let max_assoc_types;
2949
2950         match maybe_qself {
2951             Some(qself) => {
2952                 if qself.position == 0 {
2953                     return TypecheckRequired;
2954                 }
2955                 max_assoc_types = path.segments.len() - qself.position;
2956                 // Make sure the trait is valid.
2957                 let _ = self.resolve_trait_reference(id, path, max_assoc_types);
2958             }
2959             None => {
2960                 max_assoc_types = path.segments.len();
2961             }
2962         }
2963
2964         let mut resolution = self.with_no_errors(|this| {
2965             this.resolve_path(id, path, 0, namespace, check_ribs)
2966         });
2967         for depth in 1..max_assoc_types {
2968             if resolution.is_some() {
2969                 break;
2970             }
2971             self.with_no_errors(|this| {
2972                 resolution = this.resolve_path(id, path, depth, TypeNS, true);
2973             });
2974         }
2975         if let Some(DefMod(_)) = resolution.map(|r| r.base_def) {
2976             // A module is not a valid type or value.
2977             resolution = None;
2978         }
2979         ResolveAttempt(resolution)
2980     }
2981
2982     /// If `check_ribs` is true, checks the local definitions first; i.e.
2983     /// doesn't skip straight to the containing module.
2984     /// Skips `path_depth` trailing segments, which is also reflected in the
2985     /// returned value. See `middle::def::PathResolution` for more info.
2986     pub fn resolve_path(&mut self,
2987                         id: NodeId,
2988                         path: &Path,
2989                         path_depth: usize,
2990                         namespace: Namespace,
2991                         check_ribs: bool)
2992                         -> Option<PathResolution> {
2993         let span = path.span;
2994         let segments = &path.segments[..path.segments.len() - path_depth];
2995
2996         let mk_res = |(def, lp)| PathResolution::new(def, lp, path_depth);
2997
2998         if path.global {
2999             let def = self.resolve_crate_relative_path(span, segments, namespace);
3000             return def.map(mk_res);
3001         }
3002
3003         // Try to find a path to an item in a module.
3004         let last_ident = segments.last().unwrap().identifier;
3005         if segments.len() <= 1 {
3006             let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, true);
3007             return unqualified_def.and_then(|def| self.adjust_local_def(def, span))
3008                                   .map(|def| {
3009                                       PathResolution::new(def, LastMod(AllPublic), path_depth)
3010                                   });
3011         }
3012
3013         let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, false);
3014         let def = self.resolve_module_relative_path(span, segments, namespace);
3015         match (def, unqualified_def) {
3016             (Some((ref d, _)), Some(ref ud)) if *d == ud.def => {
3017                 self.session
3018                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
3019                               id,
3020                               span,
3021                               "unnecessary qualification".to_string());
3022             }
3023             _ => {}
3024         }
3025
3026         def.map(mk_res)
3027     }
3028
3029     // Resolve a single identifier
3030     fn resolve_identifier(&mut self,
3031                           identifier: hir::Ident,
3032                           namespace: Namespace,
3033                           check_ribs: bool,
3034                           record_used: bool)
3035                           -> Option<LocalDef> {
3036         // First, check to see whether the name is a primitive type.
3037         if namespace == TypeNS {
3038             if let Some(&prim_ty) = self.primitive_type_table
3039                                         .primitive_types
3040                                         .get(&identifier.unhygienic_name) {
3041                 return Some(LocalDef::from_def(DefPrimTy(prim_ty)));
3042             }
3043         }
3044
3045         if check_ribs {
3046             if let Some(def) = self.resolve_identifier_in_local_ribs(identifier, namespace) {
3047                 return Some(def);
3048             }
3049         }
3050
3051         let name = identifier.unhygienic_name;
3052         self.resolve_item_by_name_in_lexical_scope(name, namespace, record_used)
3053             .map(LocalDef::from_def)
3054     }
3055
3056     // Resolve a local definition, potentially adjusting for closures.
3057     fn adjust_local_def(&mut self, local_def: LocalDef, span: Span) -> Option<Def> {
3058         let ribs = match local_def.ribs {
3059             Some((TypeNS, i)) => &self.type_ribs[i + 1..],
3060             Some((ValueNS, i)) => &self.value_ribs[i + 1..],
3061             _ => &[] as &[_],
3062         };
3063         let mut def = local_def.def;
3064         match def {
3065             DefUpvar(..) => {
3066                 self.session.span_bug(span, &format!("unexpected {:?} in bindings", def))
3067             }
3068             DefLocal(_, node_id) => {
3069                 for rib in ribs {
3070                     match rib.kind {
3071                         NormalRibKind => {
3072                             // Nothing to do. Continue.
3073                         }
3074                         ClosureRibKind(function_id) => {
3075                             let prev_def = def;
3076                             let node_def_id = self.ast_map.local_def_id(node_id);
3077
3078                             let seen = self.freevars_seen
3079                                            .entry(function_id)
3080                                            .or_insert_with(|| NodeMap());
3081                             if let Some(&index) = seen.get(&node_id) {
3082                                 def = DefUpvar(node_def_id, node_id, index, function_id);
3083                                 continue;
3084                             }
3085                             let vec = self.freevars
3086                                           .entry(function_id)
3087                                           .or_insert_with(|| vec![]);
3088                             let depth = vec.len();
3089                             vec.push(Freevar {
3090                                 def: prev_def,
3091                                 span: span,
3092                             });
3093
3094                             def = DefUpvar(node_def_id, node_id, depth, function_id);
3095                             seen.insert(node_id, depth);
3096                         }
3097                         ItemRibKind | MethodRibKind => {
3098                             // This was an attempt to access an upvar inside a
3099                             // named function item. This is not allowed, so we
3100                             // report an error.
3101                             resolve_error(self,
3102                                           span,
3103                                           ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
3104                             return None;
3105                         }
3106                         ConstantItemRibKind => {
3107                             // Still doesn't deal with upvars
3108                             resolve_error(self,
3109                                           span,
3110                                           ResolutionError::AttemptToUseNonConstantValueInConstant);
3111                             return None;
3112                         }
3113                     }
3114                 }
3115             }
3116             DefTyParam(..) | DefSelfTy(..) => {
3117                 for rib in ribs {
3118                     match rib.kind {
3119                         NormalRibKind | MethodRibKind | ClosureRibKind(..) => {
3120                             // Nothing to do. Continue.
3121                         }
3122                         ItemRibKind => {
3123                             // This was an attempt to use a type parameter outside
3124                             // its scope.
3125
3126                             resolve_error(self,
3127                                           span,
3128                                           ResolutionError::TypeParametersFromOuterFunction);
3129                             return None;
3130                         }
3131                         ConstantItemRibKind => {
3132                             // see #9186
3133                             resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
3134                             return None;
3135                         }
3136                     }
3137                 }
3138             }
3139             _ => {}
3140         }
3141         return Some(def);
3142     }
3143
3144     // resolve a "module-relative" path, e.g. a::b::c
3145     fn resolve_module_relative_path(&mut self,
3146                                     span: Span,
3147                                     segments: &[hir::PathSegment],
3148                                     namespace: Namespace)
3149                                     -> Option<(Def, LastPrivate)> {
3150         let module_path = segments.split_last()
3151                                   .unwrap()
3152                                   .1
3153                                   .iter()
3154                                   .map(|ps| ps.identifier.name)
3155                                   .collect::<Vec<_>>();
3156
3157         let containing_module;
3158         let last_private;
3159         let current_module = self.current_module;
3160         match self.resolve_module_path(current_module,
3161                                        &module_path[..],
3162                                        UseLexicalScope,
3163                                        span,
3164                                        PathSearch) {
3165             Failed(err) => {
3166                 let (span, msg) = match err {
3167                     Some((span, msg)) => (span, msg),
3168                     None => {
3169                         let msg = format!("Use of undeclared type or module `{}`",
3170                                           names_to_string(&module_path));
3171                         (span, msg)
3172                     }
3173                 };
3174
3175                 resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
3176                 return None;
3177             }
3178             Indeterminate => panic!("indeterminate unexpected"),
3179             Success((resulting_module, resulting_last_private)) => {
3180                 containing_module = resulting_module;
3181                 last_private = resulting_last_private;
3182             }
3183         }
3184
3185         let name = segments.last().unwrap().identifier.name;
3186         let def = match self.resolve_name_in_module(containing_module,
3187                                                     name,
3188                                                     namespace,
3189                                                     NameSearchType::PathSearch,
3190                                                     false) {
3191             Success((Target { binding, .. }, _)) => {
3192                 let (def, lp) = binding.def_and_lp();
3193                 (def, last_private.or(lp))
3194             }
3195             _ => return None,
3196         };
3197         if let Some(DefId{krate: kid, ..}) = containing_module.def_id() {
3198             self.used_crates.insert(kid);
3199         }
3200         return Some(def);
3201     }
3202
3203     /// Invariant: This must be called only during main resolution, not during
3204     /// import resolution.
3205     fn resolve_crate_relative_path(&mut self,
3206                                    span: Span,
3207                                    segments: &[hir::PathSegment],
3208                                    namespace: Namespace)
3209                                    -> Option<(Def, LastPrivate)> {
3210         let module_path = segments.split_last()
3211                                   .unwrap()
3212                                   .1
3213                                   .iter()
3214                                   .map(|ps| ps.identifier.name)
3215                                   .collect::<Vec<_>>();
3216
3217         let root_module = self.graph_root;
3218
3219         let containing_module;
3220         let last_private;
3221         match self.resolve_module_path_from_root(root_module,
3222                                                  &module_path[..],
3223                                                  0,
3224                                                  span,
3225                                                  PathSearch,
3226                                                  LastMod(AllPublic)) {
3227             Failed(err) => {
3228                 let (span, msg) = match err {
3229                     Some((span, msg)) => (span, msg),
3230                     None => {
3231                         let msg = format!("Use of undeclared module `::{}`",
3232                                           names_to_string(&module_path[..]));
3233                         (span, msg)
3234                     }
3235                 };
3236
3237                 resolve_error(self, span, ResolutionError::FailedToResolve(&*msg));
3238                 return None;
3239             }
3240
3241             Indeterminate => {
3242                 panic!("indeterminate unexpected");
3243             }
3244
3245             Success((resulting_module, resulting_last_private)) => {
3246                 containing_module = resulting_module;
3247                 last_private = resulting_last_private;
3248             }
3249         }
3250
3251         let name = segments.last().unwrap().identifier.name;
3252         match self.resolve_name_in_module(containing_module,
3253                                           name,
3254                                           namespace,
3255                                           NameSearchType::PathSearch,
3256                                           false) {
3257             Success((Target { binding, .. }, _)) => {
3258                 let (def, lp) = binding.def_and_lp();
3259                 Some((def, last_private.or(lp)))
3260             }
3261             _ => None,
3262         }
3263     }
3264
3265     fn resolve_identifier_in_local_ribs(&mut self,
3266                                         ident: hir::Ident,
3267                                         namespace: Namespace)
3268                                         -> Option<LocalDef> {
3269         // Check the local set of ribs.
3270         let (name, ribs) = match namespace {
3271             ValueNS => (ident.name, &self.value_ribs),
3272             TypeNS => (ident.unhygienic_name, &self.type_ribs),
3273         };
3274
3275         for (i, rib) in ribs.iter().enumerate().rev() {
3276             if let Some(def_like) = rib.bindings.get(&name).cloned() {
3277                 match def_like {
3278                     DlDef(def) => {
3279                         debug!("(resolving path in local ribs) resolved `{}` to {:?} at {}",
3280                                name,
3281                                def,
3282                                i);
3283                         return Some(LocalDef {
3284                             ribs: Some((namespace, i)),
3285                             def: def,
3286                         });
3287                     }
3288                     def_like => {
3289                         debug!("(resolving path in local ribs) resolved `{}` to pseudo-def {:?}",
3290                                name,
3291                                def_like);
3292                         return None;
3293                     }
3294                 }
3295             }
3296         }
3297
3298         None
3299     }
3300
3301     fn resolve_item_by_name_in_lexical_scope(&mut self,
3302                                              name: Name,
3303                                              namespace: Namespace,
3304                                              record_used: bool)
3305                                              -> Option<Def> {
3306         // Check the items.
3307         let module = self.current_module;
3308         match self.resolve_item_in_lexical_scope(module, name, namespace, record_used) {
3309             Success((target, _)) => {
3310                 match target.binding.def() {
3311                     None => {
3312                         // This can happen if we were looking for a type and
3313                         // found a module instead. Modules don't have defs.
3314                         debug!("(resolving item path by identifier in lexical scope) failed to \
3315                                 resolve {} after success...",
3316                                name);
3317                         None
3318                     }
3319                     Some(def) => {
3320                         debug!("(resolving item path in lexical scope) resolved `{}` to item",
3321                                name);
3322                         // This lookup is "all public" because it only searched
3323                         // for one identifier in the current module (couldn't
3324                         // have passed through reexports or anything like that.
3325                         Some(def)
3326                     }
3327                 }
3328             }
3329             Indeterminate => {
3330                 panic!("unexpected indeterminate result");
3331             }
3332             Failed(err) => {
3333                 debug!("(resolving item path by identifier in lexical scope) failed to resolve {}",
3334                        name);
3335
3336                 if let Some((span, msg)) = err {
3337                     resolve_error(self, span, ResolutionError::FailedToResolve(&*msg))
3338                 }
3339
3340                 None
3341             }
3342         }
3343     }
3344
3345     fn with_no_errors<T, F>(&mut self, f: F) -> T
3346         where F: FnOnce(&mut Resolver) -> T
3347     {
3348         self.emit_errors = false;
3349         let rs = f(self);
3350         self.emit_errors = true;
3351         rs
3352     }
3353
3354     fn find_fallback_in_self_type(&mut self, name: Name) -> FallbackSuggestion {
3355         fn extract_path_and_node_id(t: &Ty,
3356                                     allow: FallbackChecks)
3357                                     -> Option<(Path, NodeId, FallbackChecks)> {
3358             match t.node {
3359                 TyPath(None, ref path) => Some((path.clone(), t.id, allow)),
3360                 TyPtr(ref mut_ty) => extract_path_and_node_id(&*mut_ty.ty, OnlyTraitAndStatics),
3361                 TyRptr(_, ref mut_ty) => extract_path_and_node_id(&*mut_ty.ty, allow),
3362                 // This doesn't handle the remaining `Ty` variants as they are not
3363                 // that commonly the self_type, it might be interesting to provide
3364                 // support for those in future.
3365                 _ => None,
3366             }
3367         }
3368
3369         fn get_module<'a, 'tcx>(this: &mut Resolver<'a, 'tcx>,
3370                                 span: Span,
3371                                 name_path: &[ast::Name])
3372                                 -> Option<Module<'a>> {
3373             let root = this.current_module;
3374             let last_name = name_path.last().unwrap();
3375
3376             if name_path.len() == 1 {
3377                 match this.primitive_type_table.primitive_types.get(last_name) {
3378                     Some(_) => None,
3379                     None => {
3380                         match this.current_module.children.borrow().get(last_name) {
3381                             Some(child) => child.type_ns.module(),
3382                             None => None,
3383                         }
3384                     }
3385                 }
3386             } else {
3387                 match this.resolve_module_path(root,
3388                                                &name_path[..],
3389                                                UseLexicalScope,
3390                                                span,
3391                                                PathSearch) {
3392                     Success((module, _)) => Some(module),
3393                     _ => None,
3394                 }
3395             }
3396         }
3397
3398         fn is_static_method(this: &Resolver, did: DefId) -> bool {
3399             if let Some(node_id) = this.ast_map.as_local_node_id(did) {
3400                 let sig = match this.ast_map.get(node_id) {
3401                     hir_map::NodeTraitItem(trait_item) => match trait_item.node {
3402                         hir::MethodTraitItem(ref sig, _) => sig,
3403                         _ => return false,
3404                     },
3405                     hir_map::NodeImplItem(impl_item) => match impl_item.node {
3406                         hir::ImplItemKind::Method(ref sig, _) => sig,
3407                         _ => return false,
3408                     },
3409                     _ => return false,
3410                 };
3411                 sig.explicit_self.node == hir::SelfStatic
3412             } else {
3413                 this.session.cstore.is_static_method(did)
3414             }
3415         }
3416
3417         let (path, node_id, allowed) = match self.current_self_type {
3418             Some(ref ty) => match extract_path_and_node_id(ty, Everything) {
3419                 Some(x) => x,
3420                 None => return NoSuggestion,
3421             },
3422             None => return NoSuggestion,
3423         };
3424
3425         if allowed == Everything {
3426             // Look for a field with the same name in the current self_type.
3427             match self.def_map.borrow().get(&node_id).map(|d| d.full_def()) {
3428                 Some(DefTy(did, _)) |
3429                 Some(DefStruct(did)) |
3430                 Some(DefVariant(_, did, _)) => match self.structs.get(&did) {
3431                     None => {}
3432                     Some(fields) => {
3433                         if fields.iter().any(|&field_name| name == field_name) {
3434                             return Field;
3435                         }
3436                     }
3437                 },
3438                 _ => {} // Self type didn't resolve properly
3439             }
3440         }
3441
3442         let name_path = path.segments.iter().map(|seg| seg.identifier.name).collect::<Vec<_>>();
3443
3444         // Look for a method in the current self type's impl module.
3445         if let Some(module) = get_module(self, path.span, &name_path) {
3446             if let Some(binding) = module.children.borrow().get(&name) {
3447                 if let Some(DefMethod(did)) = binding.value_ns.def() {
3448                     if is_static_method(self, did) {
3449                         return StaticMethod(path_names_to_string(&path, 0));
3450                     }
3451                     if self.current_trait_ref.is_some() {
3452                         return TraitItem;
3453                     } else if allowed == Everything {
3454                         return Method;
3455                     }
3456                 }
3457             }
3458         }
3459
3460         // Look for a method in the current trait.
3461         if let Some((trait_did, ref trait_ref)) = self.current_trait_ref {
3462             if let Some(&did) = self.trait_item_map.get(&(name, trait_did)) {
3463                 if is_static_method(self, did) {
3464                     return TraitMethod(path_names_to_string(&trait_ref.path, 0));
3465                 } else {
3466                     return TraitItem;
3467                 }
3468             }
3469         }
3470
3471         NoSuggestion
3472     }
3473
3474     fn find_best_match(&mut self, name: &str) -> SuggestionType {
3475         if let Some(macro_name) = self.session.available_macros
3476                                   .borrow().iter().find(|n| n.as_str() == name) {
3477             return SuggestionType::Macro(format!("{}!", macro_name));
3478         }
3479
3480         let names = self.value_ribs
3481                     .iter()
3482                     .rev()
3483                     .flat_map(|rib| rib.bindings.keys());
3484
3485         if let Some(found) = find_best_match_for_name(names, name, None) {
3486             if name != &*found {
3487                 return SuggestionType::Function(found);
3488             }
3489         } SuggestionType::NotFound
3490     }
3491
3492     fn resolve_expr(&mut self, expr: &Expr) {
3493         // First, record candidate traits for this expression if it could
3494         // result in the invocation of a method call.
3495
3496         self.record_candidate_traits_for_expr_if_necessary(expr);
3497
3498         // Next, resolve the node.
3499         match expr.node {
3500             ExprPath(ref maybe_qself, ref path) => {
3501                 let resolution = match self.resolve_possibly_assoc_item(expr.id,
3502                                                                         maybe_qself.as_ref(),
3503                                                                         path,
3504                                                                         ValueNS,
3505                                                                         true) {
3506                     // `<T>::a::b::c` is resolved by typeck alone.
3507                     TypecheckRequired => {
3508                         let method_name = path.segments.last().unwrap().identifier.name;
3509                         let traits = self.get_traits_containing_item(method_name);
3510                         self.trait_map.insert(expr.id, traits);
3511                         intravisit::walk_expr(self, expr);
3512                         return;
3513                     }
3514                     ResolveAttempt(resolution) => resolution,
3515                 };
3516
3517                 // This is a local path in the value namespace. Walk through
3518                 // scopes looking for it.
3519                 if let Some(path_res) = resolution {
3520                     // Check if struct variant
3521                     if let DefVariant(_, _, true) = path_res.base_def {
3522                         let path_name = path_names_to_string(path, 0);
3523
3524                         let mut err = resolve_struct_error(self,
3525                                         expr.span,
3526                                         ResolutionError::StructVariantUsedAsFunction(&*path_name));
3527
3528                         let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3529                                           path_name);
3530                         if self.emit_errors {
3531                             err.fileline_help(expr.span, &msg);
3532                         } else {
3533                             err.span_help(expr.span, &msg);
3534                         }
3535                         err.emit();
3536                         self.record_def(expr.id, err_path_resolution());
3537                     } else {
3538                         // Write the result into the def map.
3539                         debug!("(resolving expr) resolved `{}`",
3540                                path_names_to_string(path, 0));
3541
3542                         // Partial resolutions will need the set of traits in scope,
3543                         // so they can be completed during typeck.
3544                         if path_res.depth != 0 {
3545                             let method_name = path.segments.last().unwrap().identifier.name;
3546                             let traits = self.get_traits_containing_item(method_name);
3547                             self.trait_map.insert(expr.id, traits);
3548                         }
3549
3550                         self.record_def(expr.id, path_res);
3551                     }
3552                 } else {
3553                     // Be helpful if the name refers to a struct
3554                     // (The pattern matching def_tys where the id is in self.structs
3555                     // matches on regular structs while excluding tuple- and enum-like
3556                     // structs, which wouldn't result in this error.)
3557                     let path_name = path_names_to_string(path, 0);
3558                     let type_res = self.with_no_errors(|this| {
3559                         this.resolve_path(expr.id, path, 0, TypeNS, false)
3560                     });
3561
3562                     self.record_def(expr.id, err_path_resolution());
3563                     match type_res.map(|r| r.base_def) {
3564                         Some(DefTy(struct_id, _)) if self.structs.contains_key(&struct_id) => {
3565                             let mut err = resolve_struct_error(self,
3566                                 expr.span,
3567                                 ResolutionError::StructVariantUsedAsFunction(&*path_name));
3568
3569                             let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3570                                               path_name);
3571                             if self.emit_errors {
3572                                 err.fileline_help(expr.span, &msg);
3573                             } else {
3574                                 err.span_help(expr.span, &msg);
3575                             }
3576                             err.emit();
3577                         }
3578                         _ => {
3579                             // Keep reporting some errors even if they're ignored above.
3580                             self.resolve_path(expr.id, path, 0, ValueNS, true);
3581
3582                             let mut method_scope = false;
3583                             self.value_ribs.iter().rev().all(|rib| {
3584                                 method_scope = match rib.kind {
3585                                     MethodRibKind => true,
3586                                     ItemRibKind | ConstantItemRibKind => false,
3587                                     _ => return true, // Keep advancing
3588                                 };
3589                                 false // Stop advancing
3590                             });
3591
3592                             if method_scope && special_names::self_.as_str() == &path_name[..] {
3593                                 resolve_error(self,
3594                                               expr.span,
3595                                               ResolutionError::SelfNotAvailableInStaticMethod);
3596                             } else {
3597                                 let last_name = path.segments.last().unwrap().identifier.name;
3598                                 let mut msg = match self.find_fallback_in_self_type(last_name) {
3599                                     NoSuggestion => {
3600                                         // limit search to 5 to reduce the number
3601                                         // of stupid suggestions
3602                                         match self.find_best_match(&path_name) {
3603                                             SuggestionType::Macro(s) => {
3604                                                 format!("the macro `{}`", s)
3605                                             }
3606                                             SuggestionType::Function(s) => format!("`{}`", s),
3607                                             SuggestionType::NotFound => "".to_string(),
3608                                         }
3609                                     }
3610                                     Field => format!("`self.{}`", path_name),
3611                                     Method |
3612                                     TraitItem => format!("to call `self.{}`", path_name),
3613                                     TraitMethod(path_str) |
3614                                     StaticMethod(path_str) =>
3615                                         format!("to call `{}::{}`", path_str, path_name),
3616                                 };
3617
3618                                 let mut context =  UnresolvedNameContext::Other;
3619                                 if !msg.is_empty() {
3620                                     msg = format!(". Did you mean {}?", msg);
3621                                 } else {
3622                                     // we check if this a module and if so, we display a help
3623                                     // message
3624                                     let name_path = path.segments.iter()
3625                                                         .map(|seg| seg.identifier.name)
3626                                                         .collect::<Vec<_>>();
3627                                     let current_module = self.current_module;
3628
3629                                     match self.resolve_module_path(current_module,
3630                                                    &name_path[..],
3631                                                    UseLexicalScope,
3632                                                    expr.span,
3633                                                    PathSearch) {
3634                                         Success(_) => {
3635                                             context = UnresolvedNameContext::PathIsMod(expr.id);
3636                                         },
3637                                         _ => {},
3638                                     };
3639                                 }
3640
3641                                 resolve_error(self,
3642                                               expr.span,
3643                                               ResolutionError::UnresolvedName(
3644                                                   &*path_name, &*msg, context));
3645                             }
3646                         }
3647                     }
3648                 }
3649
3650                 intravisit::walk_expr(self, expr);
3651             }
3652
3653             ExprStruct(ref path, _, _) => {
3654                 // Resolve the path to the structure it goes to. We don't
3655                 // check to ensure that the path is actually a structure; that
3656                 // is checked later during typeck.
3657                 match self.resolve_path(expr.id, path, 0, TypeNS, false) {
3658                     Some(definition) => self.record_def(expr.id, definition),
3659                     None => {
3660                         debug!("(resolving expression) didn't find struct def",);
3661
3662                         resolve_error(self,
3663                                       path.span,
3664                                       ResolutionError::DoesNotNameAStruct(
3665                                                                 &*path_names_to_string(path, 0))
3666                                      );
3667                         self.record_def(expr.id, err_path_resolution());
3668                     }
3669                 }
3670
3671                 intravisit::walk_expr(self, expr);
3672             }
3673
3674             ExprLoop(_, Some(label)) | ExprWhile(_, _, Some(label)) => {
3675                 self.with_label_rib(|this| {
3676                     let def_like = DlDef(DefLabel(expr.id));
3677
3678                     {
3679                         let rib = this.label_ribs.last_mut().unwrap();
3680                         rib.bindings.insert(label.name, def_like);
3681                     }
3682
3683                     intravisit::walk_expr(this, expr);
3684                 })
3685             }
3686
3687             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
3688                 match self.search_label(label.node.name) {
3689                     None => {
3690                         self.record_def(expr.id, err_path_resolution());
3691                         resolve_error(self,
3692                                       label.span,
3693                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
3694                     }
3695                     Some(DlDef(def @ DefLabel(_))) => {
3696                         // Since this def is a label, it is never read.
3697                         self.record_def(expr.id,
3698                                         PathResolution {
3699                                             base_def: def,
3700                                             last_private: LastMod(AllPublic),
3701                                             depth: 0,
3702                                         })
3703                     }
3704                     Some(_) => {
3705                         self.session.span_bug(expr.span, "label wasn't mapped to a label def!")
3706                     }
3707                 }
3708             }
3709
3710             _ => {
3711                 intravisit::walk_expr(self, expr);
3712             }
3713         }
3714     }
3715
3716     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3717         match expr.node {
3718             ExprField(_, name) => {
3719                 // FIXME(#6890): Even though you can't treat a method like a
3720                 // field, we need to add any trait methods we find that match
3721                 // the field name so that we can do some nice error reporting
3722                 // later on in typeck.
3723                 let traits = self.get_traits_containing_item(name.node);
3724                 self.trait_map.insert(expr.id, traits);
3725             }
3726             ExprMethodCall(name, _, _) => {
3727                 debug!("(recording candidate traits for expr) recording traits for {}",
3728                        expr.id);
3729                 let traits = self.get_traits_containing_item(name.node);
3730                 self.trait_map.insert(expr.id, traits);
3731             }
3732             _ => {
3733                 // Nothing to do.
3734             }
3735         }
3736     }
3737
3738     fn get_traits_containing_item(&mut self, name: Name) -> Vec<DefId> {
3739         debug!("(getting traits containing item) looking for '{}'", name);
3740
3741         fn add_trait_info(found_traits: &mut Vec<DefId>, trait_def_id: DefId, name: Name) {
3742             debug!("(adding trait info) found trait {:?} for method '{}'",
3743                    trait_def_id,
3744                    name);
3745             found_traits.push(trait_def_id);
3746         }
3747
3748         let mut found_traits = Vec::new();
3749         let mut search_module = self.current_module;
3750         loop {
3751             // Look for the current trait.
3752             match self.current_trait_ref {
3753                 Some((trait_def_id, _)) => {
3754                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3755                         add_trait_info(&mut found_traits, trait_def_id, name);
3756                     }
3757                 }
3758                 None => {} // Nothing to do.
3759             }
3760
3761             // Look for trait children.
3762             build_reduced_graph::populate_module_if_necessary(self, &search_module);
3763
3764             {
3765                 for (_, child_names) in search_module.children.borrow().iter() {
3766                     let def = match child_names.type_ns.def() {
3767                         Some(def) => def,
3768                         None => continue,
3769                     };
3770                     let trait_def_id = match def {
3771                         DefTrait(trait_def_id) => trait_def_id,
3772                         _ => continue,
3773                     };
3774                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3775                         add_trait_info(&mut found_traits, trait_def_id, name);
3776                     }
3777                 }
3778             }
3779
3780             // Look for imports.
3781             for (_, import) in search_module.import_resolutions.borrow().iter() {
3782                 let target = match import.type_ns.target {
3783                     None => continue,
3784                     Some(ref target) => target,
3785                 };
3786                 let did = match target.binding.def() {
3787                     Some(DefTrait(trait_def_id)) => trait_def_id,
3788                     Some(..) | None => continue,
3789                 };
3790                 if self.trait_item_map.contains_key(&(name, did)) {
3791                     add_trait_info(&mut found_traits, did, name);
3792                     let id = import.type_ns.id;
3793                     self.used_imports.insert((id, TypeNS));
3794                     let trait_name = self.get_trait_name(did);
3795                     self.record_import_use(id, trait_name);
3796                     if let Some(DefId{krate: kid, ..}) = target.target_module.def_id() {
3797                         self.used_crates.insert(kid);
3798                     }
3799                 }
3800             }
3801
3802             match search_module.parent_link {
3803                 NoParentLink | ModuleParentLink(..) => break,
3804                 BlockParentLink(parent_module, _) => {
3805                     search_module = parent_module;
3806                 }
3807             }
3808         }
3809
3810         found_traits
3811     }
3812
3813     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3814         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3815         assert!(match resolution.last_private {
3816                     LastImport{..} => false,
3817                     _ => true,
3818                 },
3819                 "Import should only be used for `use` directives");
3820
3821         if let Some(prev_res) = self.def_map.borrow_mut().insert(node_id, resolution) {
3822             let span = self.ast_map.opt_span(node_id).unwrap_or(codemap::DUMMY_SP);
3823             self.session.span_bug(span,
3824                                   &format!("path resolved multiple times ({:?} before, {:?} now)",
3825                                            prev_res,
3826                                            resolution));
3827         }
3828     }
3829
3830     fn enforce_default_binding_mode(&mut self,
3831                                     pat: &Pat,
3832                                     pat_binding_mode: BindingMode,
3833                                     descr: &str) {
3834         match pat_binding_mode {
3835             BindByValue(_) => {}
3836             BindByRef(..) => {
3837                 resolve_error(self,
3838                               pat.span,
3839                               ResolutionError::CannotUseRefBindingModeWith(descr));
3840             }
3841         }
3842     }
3843
3844     //
3845     // Diagnostics
3846     //
3847     // Diagnostics are not particularly efficient, because they're rarely
3848     // hit.
3849     //
3850
3851     #[allow(dead_code)]   // useful for debugging
3852     fn dump_module(&mut self, module_: Module<'a>) {
3853         debug!("Dump of module `{}`:", module_to_string(&*module_));
3854
3855         debug!("Children:");
3856         build_reduced_graph::populate_module_if_necessary(self, &module_);
3857         for (&name, _) in module_.children.borrow().iter() {
3858             debug!("* {}", name);
3859         }
3860
3861         debug!("Import resolutions:");
3862         let import_resolutions = module_.import_resolutions.borrow();
3863         for (&name, import_resolution) in import_resolutions.iter() {
3864             let value_repr;
3865             match import_resolution.value_ns.target {
3866                 None => {
3867                     value_repr = "".to_string();
3868                 }
3869                 Some(_) => {
3870                     value_repr = " value:?".to_string();
3871                     // FIXME #4954
3872                 }
3873             }
3874
3875             let type_repr;
3876             match import_resolution.type_ns.target {
3877                 None => {
3878                     type_repr = "".to_string();
3879                 }
3880                 Some(_) => {
3881                     type_repr = " type:?".to_string();
3882                     // FIXME #4954
3883                 }
3884             }
3885
3886             debug!("* {}:{}{}", name, value_repr, type_repr);
3887         }
3888     }
3889 }
3890
3891
3892 fn names_to_string(names: &[Name]) -> String {
3893     let mut first = true;
3894     let mut result = String::new();
3895     for name in names {
3896         if first {
3897             first = false
3898         } else {
3899             result.push_str("::")
3900         }
3901         result.push_str(&name.as_str());
3902     }
3903     result
3904 }
3905
3906 fn path_names_to_string(path: &Path, depth: usize) -> String {
3907     let names: Vec<ast::Name> = path.segments[..path.segments.len() - depth]
3908                                     .iter()
3909                                     .map(|seg| seg.identifier.name)
3910                                     .collect();
3911     names_to_string(&names[..])
3912 }
3913
3914 /// A somewhat inefficient routine to obtain the name of a module.
3915 fn module_to_string<'a>(module: Module<'a>) -> String {
3916     let mut names = Vec::new();
3917
3918     fn collect_mod<'a>(names: &mut Vec<ast::Name>, module: Module<'a>) {
3919         match module.parent_link {
3920             NoParentLink => {}
3921             ModuleParentLink(ref module, name) => {
3922                 names.push(name);
3923                 collect_mod(names, module);
3924             }
3925             BlockParentLink(ref module, _) => {
3926                 // danger, shouldn't be ident?
3927                 names.push(special_idents::opaque.name);
3928                 collect_mod(names, module);
3929             }
3930         }
3931     }
3932     collect_mod(&mut names, module);
3933
3934     if names.is_empty() {
3935         return "???".to_string();
3936     }
3937     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
3938 }
3939
3940 fn err_path_resolution() -> PathResolution {
3941     PathResolution {
3942         base_def: DefErr,
3943         last_private: LastMod(AllPublic),
3944         depth: 0,
3945     }
3946 }
3947
3948
3949 pub struct CrateMap {
3950     pub def_map: RefCell<DefMap>,
3951     pub freevars: FreevarMap,
3952     pub export_map: ExportMap,
3953     pub trait_map: TraitMap,
3954     pub external_exports: ExternalExports,
3955     pub glob_map: Option<GlobMap>,
3956 }
3957
3958 #[derive(PartialEq,Copy, Clone)]
3959 pub enum MakeGlobMap {
3960     Yes,
3961     No,
3962 }
3963
3964 /// Entry point to crate resolution.
3965 pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
3966                                ast_map: &'a hir_map::Map<'tcx>,
3967                                make_glob_map: MakeGlobMap)
3968                                -> CrateMap {
3969     let krate = ast_map.krate();
3970     let arenas = Resolver::arenas();
3971     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, &arenas, None);
3972
3973     resolver.resolve_crate(krate);
3974
3975     check_unused::check_crate(&mut resolver, krate);
3976
3977     CrateMap {
3978         def_map: resolver.def_map,
3979         freevars: resolver.freevars,
3980         export_map: resolver.export_map,
3981         trait_map: resolver.trait_map,
3982         external_exports: resolver.external_exports,
3983         glob_map: if resolver.make_glob_map {
3984             Some(resolver.glob_map)
3985         } else {
3986             None
3987         },
3988     }
3989 }
3990
3991 /// Builds a name resolution walker to be used within this module,
3992 /// or used externally, with an optional callback function.
3993 ///
3994 /// The callback takes a &mut bool which allows callbacks to end a
3995 /// walk when set to true, passing through the rest of the walk, while
3996 /// preserving the ribs + current module. This allows resolve_path
3997 /// calls to be made with the correct scope info. The node in the
3998 /// callback corresponds to the current node in the walk.
3999 pub fn create_resolver<'a, 'tcx>(session: &'a Session,
4000                                  ast_map: &'a hir_map::Map<'tcx>,
4001                                  krate: &'a Crate,
4002                                  make_glob_map: MakeGlobMap,
4003                                  arenas: &'a ResolverArenas<'a>,
4004                                  callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>)
4005                                  -> Resolver<'a, 'tcx> {
4006     let mut resolver = Resolver::new(session, ast_map, make_glob_map, arenas);
4007
4008     resolver.callback = callback;
4009
4010     build_reduced_graph::build_reduced_graph(&mut resolver, krate);
4011     session.abort_if_errors();
4012
4013     resolve_imports::resolve_imports(&mut resolver);
4014     session.abort_if_errors();
4015
4016     resolver
4017 }
4018
4019 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }