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 #![cfg_attr(not(stage0), deny(warnings))]
  19
  20 #![feature(associated_consts)]
  21 #![feature(borrow_state)]
  22 #![feature(rustc_diagnostic_macros)]
  23 #![feature(rustc_private)]
  24 #![feature(staged_api)]
  25
  26 #[macro_use]
  27 extern crate log;
  28 #[macro_use]
  29 extern crate syntax;
  30 extern crate arena;
  31 #[macro_use]
  32 #[no_link]
  33 extern crate rustc_bitflags;
  34 extern crate rustc_front;
  35 extern crate rustc;
  36
  37 use self::PatternBindingMode::*;
  38 use self::Namespace::*;
  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::BareIdentifierPatternResolution::*;
  47 use self::ParentLink::*;
  48 use self::FallbackChecks::*;
  49
  50 use rustc::dep_graph::DepNode;
  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::{self, FloatTy};
  64 use syntax::ast::{CRATE_NODE_ID, Name, NodeId, CrateNum, IntTy, UintTy};
  65 use syntax::attr::AttrMetaMethods;
  66 use syntax::codemap::{self, Span, Pos};
  67 use syntax::errors::DiagnosticBuilder;
  68 use syntax::parse::token::{self, special_names, special_idents};
  69 use syntax::util::lev_distance::find_best_match_for_name;
  70
  71 use rustc_front::intravisit::{self, FnKind, Visitor};
  72 use rustc_front::hir;
  73 use rustc_front::hir::{Arm, BindByRef, BindByValue, BindingMode, Block};
  74 use rustc_front::hir::Crate;
  75 use rustc_front::hir::{Expr, ExprAgain, ExprBreak, ExprCall, ExprField};
  76 use rustc_front::hir::{ExprLoop, ExprWhile, ExprMethodCall};
  77 use rustc_front::hir::{ExprPath, ExprStruct, FnDecl};
  78 use rustc_front::hir::{ForeignItemFn, ForeignItemStatic, Generics};
  79 use rustc_front::hir::{ImplItem, Item, ItemConst, ItemEnum, ItemExternCrate};
  80 use rustc_front::hir::{ItemFn, ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  81 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  82 use rustc_front::hir::Local;
  83 use rustc_front::hir::{Pat, PatEnum, PatIdent, PatLit, PatQPath};
  84 use rustc_front::hir::{PatRange, PatStruct, Path, PrimTy};
  85 use rustc_front::hir::{TraitRef, Ty, TyBool, TyChar, TyFloat, TyInt};
  86 use rustc_front::hir::{TyRptr, TyStr, TyUint, TyPath, TyPtr};
  87 use rustc_front::util::walk_pat;
  88
  89 use std::collections::{HashMap, HashSet};
  90 use std::cell::{Cell, RefCell};
  91 use std::fmt;
  92 use std::mem::replace;
  93
  94 use resolve_imports::{ImportDirective, NameResolution};
  95
  96 // NB: This module needs to be declared first so diagnostics are
  97 // registered before they are used.
  98 pub mod diagnostics;
  99
 100 mod check_unused;
 101 mod build_reduced_graph;
 102 mod resolve_imports;
 103
 104 // Perform the callback, not walking deeper if the return is true
 105 macro_rules! execute_callback {
 106     ($node: expr, $walker: expr) => (
 107         if let Some(ref callback) = $walker.callback {
 108             if callback($node, &mut $walker.resolved) {
 109                 return;
 110             }
 111         }
 112     )
 113 }
 114
 115 enum SuggestionType {
 116     Macro(String),
 117     Function(token::InternedString),
 118     NotFound,
 119 }
 120
 121 pub enum ResolutionError<'a> {
 122     /// error E0401: can't use type parameters from outer function
 123     TypeParametersFromOuterFunction,
 124     /// error E0402: cannot use an outer type parameter in this context
 125     OuterTypeParameterContext,
 126     /// error E0403: the name is already used for a type parameter in this type parameter list
 127     NameAlreadyUsedInTypeParameterList(Name),
 128     /// error E0404: is not a trait
 129     IsNotATrait(&'a str),
 130     /// error E0405: use of undeclared trait name
 131     UndeclaredTraitName(&'a str),
 132     /// error E0406: undeclared associated type
 133     UndeclaredAssociatedType,
 134     /// error E0407: method is not a member of trait
 135     MethodNotMemberOfTrait(Name, &'a str),
 136     /// error E0437: type is not a member of trait
 137     TypeNotMemberOfTrait(Name, &'a str),
 138     /// error E0438: const is not a member of trait
 139     ConstNotMemberOfTrait(Name, &'a str),
 140     /// error E0408: variable `{}` from pattern #1 is not bound in pattern
 141     VariableNotBoundInPattern(Name, usize),
 142     /// error E0409: variable is bound with different mode in pattern #{} than in pattern #1
 143     VariableBoundWithDifferentMode(Name, usize),
 144     /// error E0410: variable from pattern is not bound in pattern #1
 145     VariableNotBoundInParentPattern(Name, usize),
 146     /// error E0411: use of `Self` outside of an impl or trait
 147     SelfUsedOutsideImplOrTrait,
 148     /// error E0412: use of undeclared
 149     UseOfUndeclared(&'a str, &'a str),
 150     /// error E0413: declaration shadows an enum variant or unit-like struct in scope
 151     DeclarationShadowsEnumVariantOrUnitLikeStruct(Name),
 152     /// error E0414: only irrefutable patterns allowed here
 153     OnlyIrrefutablePatternsAllowedHere(DefId, Name),
 154     /// error E0415: identifier is bound more than once in this parameter list
 155     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 156     /// error E0416: identifier is bound more than once in the same pattern
 157     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 158     /// error E0417: static variables cannot be referenced in a pattern
 159     StaticVariableReference,
 160     /// error E0418: is not an enum variant, struct or const
 161     NotAnEnumVariantStructOrConst(&'a str),
 162     /// error E0419: unresolved enum variant, struct or const
 163     UnresolvedEnumVariantStructOrConst(&'a str),
 164     /// error E0420: is not an associated const
 165     NotAnAssociatedConst(&'a str),
 166     /// error E0421: unresolved associated const
 167     UnresolvedAssociatedConst(&'a str),
 168     /// error E0422: does not name a struct
 169     DoesNotNameAStruct(&'a str),
 170     /// error E0423: is a struct variant name, but this expression uses it like a function name
 171     StructVariantUsedAsFunction(&'a str),
 172     /// error E0424: `self` is not available in a static method
 173     SelfNotAvailableInStaticMethod,
 174     /// error E0425: unresolved name
 175     UnresolvedName(&'a str, &'a str, UnresolvedNameContext),
 176     /// error E0426: use of undeclared label
 177     UndeclaredLabel(&'a str),
 178     /// error E0427: cannot use `ref` binding mode with ...
 179     CannotUseRefBindingModeWith(&'a str),
 180     /// error E0428: duplicate definition
 181     DuplicateDefinition(&'a str, Name),
 182     /// error E0429: `self` imports are only allowed within a { } list
 183     SelfImportsOnlyAllowedWithin,
 184     /// error E0430: `self` import can only appear once in the list
 185     SelfImportCanOnlyAppearOnceInTheList,
 186     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 187     SelfImportOnlyInImportListWithNonEmptyPrefix,
 188     /// error E0432: unresolved import
 189     UnresolvedImport(Option<(&'a str, &'a str)>),
 190     /// error E0433: failed to resolve
 191     FailedToResolve(&'a str),
 192     /// error E0434: can't capture dynamic environment in a fn item
 193     CannotCaptureDynamicEnvironmentInFnItem,
 194     /// error E0435: attempt to use a non-constant value in a constant
 195     AttemptToUseNonConstantValueInConstant,
 196 }
 197
 198 /// Context of where `ResolutionError::UnresolvedName` arose.
 199 #[derive(Clone, PartialEq, Eq, Debug)]
 200 pub enum UnresolvedNameContext {
 201     /// `PathIsMod(id)` indicates that a given path, used in
 202     /// expression context, actually resolved to a module rather than
 203     /// a value. The `id` attached to the variant is the node id of
 204     /// the erroneous path expression.
 205     PathIsMod(ast::NodeId),
 206
 207     /// `Other` means we have no extra information about the context
 208     /// of the unresolved name error. (Maybe we could eliminate all
 209     /// such cases; but for now, this is an information-free default.)
 210     Other,
 211 }
 212
 213 fn resolve_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 214                                        span: syntax::codemap::Span,
 215                                        resolution_error: ResolutionError<'b>) {
 216     resolve_struct_error(resolver, span, resolution_error).emit();
 217 }
 218
 219 fn resolve_struct_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 220                                               span: syntax::codemap::Span,
 221                                               resolution_error: ResolutionError<'b>)
 222                                               -> DiagnosticBuilder<'a> {
 223     if !resolver.emit_errors {
 224         return resolver.session.diagnostic().struct_dummy();
 225     }
 226
 227     match resolution_error {
 228         ResolutionError::TypeParametersFromOuterFunction => {
 229             struct_span_err!(resolver.session,
 230                              span,
 231                              E0401,
 232                              "can't use type parameters from outer function; try using a local \
 233                               type parameter instead")
 234         }
 235         ResolutionError::OuterTypeParameterContext => {
 236             struct_span_err!(resolver.session,
 237                              span,
 238                              E0402,
 239                              "cannot use an outer type parameter in this context")
 240         }
 241         ResolutionError::NameAlreadyUsedInTypeParameterList(name) => {
 242             struct_span_err!(resolver.session,
 243                              span,
 244                              E0403,
 245                              "the name `{}` is already used for a type parameter in this type \
 246                               parameter list",
 247                              name)
 248         }
 249         ResolutionError::IsNotATrait(name) => {
 250             struct_span_err!(resolver.session, span, E0404, "`{}` is not a trait", name)
 251         }
 252         ResolutionError::UndeclaredTraitName(name) => {
 253             struct_span_err!(resolver.session,
 254                              span,
 255                              E0405,
 256                              "use of undeclared trait name `{}`",
 257                              name)
 258         }
 259         ResolutionError::UndeclaredAssociatedType => {
 260             struct_span_err!(resolver.session, span, E0406, "undeclared associated type")
 261         }
 262         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 263             struct_span_err!(resolver.session,
 264                              span,
 265                              E0407,
 266                              "method `{}` is not a member of trait `{}`",
 267                              method,
 268                              trait_)
 269         }
 270         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 271             struct_span_err!(resolver.session,
 272                              span,
 273                              E0437,
 274                              "type `{}` is not a member of trait `{}`",
 275                              type_,
 276                              trait_)
 277         }
 278         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 279             struct_span_err!(resolver.session,
 280                              span,
 281                              E0438,
 282                              "const `{}` is not a member of trait `{}`",
 283                              const_,
 284                              trait_)
 285         }
 286         ResolutionError::VariableNotBoundInPattern(variable_name, pattern_number) => {
 287             struct_span_err!(resolver.session,
 288                              span,
 289                              E0408,
 290                              "variable `{}` from pattern #1 is not bound in pattern #{}",
 291                              variable_name,
 292                              pattern_number)
 293         }
 294         ResolutionError::VariableBoundWithDifferentMode(variable_name, pattern_number) => {
 295             struct_span_err!(resolver.session,
 296                              span,
 297                              E0409,
 298                              "variable `{}` is bound with different mode in pattern #{} than in \
 299                               pattern #1",
 300                              variable_name,
 301                              pattern_number)
 302         }
 303         ResolutionError::VariableNotBoundInParentPattern(variable_name, pattern_number) => {
 304             struct_span_err!(resolver.session,
 305                              span,
 306                              E0410,
 307                              "variable `{}` from pattern #{} is not bound in pattern #1",
 308                              variable_name,
 309                              pattern_number)
 310         }
 311         ResolutionError::SelfUsedOutsideImplOrTrait => {
 312             struct_span_err!(resolver.session,
 313                              span,
 314                              E0411,
 315                              "use of `Self` outside of an impl or trait")
 316         }
 317         ResolutionError::UseOfUndeclared(kind, name) => {
 318             struct_span_err!(resolver.session,
 319                              span,
 320                              E0412,
 321                              "use of undeclared {} `{}`",
 322                              kind,
 323                              name)
 324         }
 325         ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(name) => {
 326             struct_span_err!(resolver.session,
 327                              span,
 328                              E0413,
 329                              "declaration of `{}` shadows an enum variant \
 330                               or unit-like struct in scope",
 331                              name)
 332         }
 333         ResolutionError::OnlyIrrefutablePatternsAllowedHere(did, name) => {
 334             let mut err = struct_span_err!(resolver.session,
 335                                            span,
 336                                            E0414,
 337                                            "only irrefutable patterns allowed here");
 338             err.span_note(span,
 339                           "there already is a constant in scope sharing the same \
 340                            name as this pattern");
 341             if let Some(sp) = resolver.ast_map.span_if_local(did) {
 342                 err.span_note(sp, "constant defined here");
 343             }
 344             if let Success(binding) = resolver.current_module.resolve_name(name, ValueNS, true) {
 345                 if binding.is_import() {
 346                     err.span_note(binding.span.unwrap(), "constant imported here");
 347                 }
 348             }
 349             err
 350         }
 351         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 352             struct_span_err!(resolver.session,
 353                              span,
 354                              E0415,
 355                              "identifier `{}` is bound more than once in this parameter list",
 356                              identifier)
 357         }
 358         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 359             struct_span_err!(resolver.session,
 360                              span,
 361                              E0416,
 362                              "identifier `{}` is bound more than once in the same pattern",
 363                              identifier)
 364         }
 365         ResolutionError::StaticVariableReference => {
 366             struct_span_err!(resolver.session,
 367                              span,
 368                              E0417,
 369                              "static variables cannot be referenced in a pattern, use a \
 370                               `const` instead")
 371         }
 372         ResolutionError::NotAnEnumVariantStructOrConst(name) => {
 373             struct_span_err!(resolver.session,
 374                              span,
 375                              E0418,
 376                              "`{}` is not an enum variant, struct or const",
 377                              name)
 378         }
 379         ResolutionError::UnresolvedEnumVariantStructOrConst(name) => {
 380             struct_span_err!(resolver.session,
 381                              span,
 382                              E0419,
 383                              "unresolved enum variant, struct or const `{}`",
 384                              name)
 385         }
 386         ResolutionError::NotAnAssociatedConst(name) => {
 387             struct_span_err!(resolver.session,
 388                              span,
 389                              E0420,
 390                              "`{}` is not an associated const",
 391                              name)
 392         }
 393         ResolutionError::UnresolvedAssociatedConst(name) => {
 394             struct_span_err!(resolver.session,
 395                              span,
 396                              E0421,
 397                              "unresolved associated const `{}`",
 398                              name)
 399         }
 400         ResolutionError::DoesNotNameAStruct(name) => {
 401             struct_span_err!(resolver.session,
 402                              span,
 403                              E0422,
 404                              "`{}` does not name a structure",
 405                              name)
 406         }
 407         ResolutionError::StructVariantUsedAsFunction(path_name) => {
 408             struct_span_err!(resolver.session,
 409                              span,
 410                              E0423,
 411                              "`{}` is the name of a struct or struct variant, but this expression \
 412                              uses it like a function name",
 413                              path_name)
 414         }
 415         ResolutionError::SelfNotAvailableInStaticMethod => {
 416             struct_span_err!(resolver.session,
 417                              span,
 418                              E0424,
 419                              "`self` is not available in a static method. Maybe a `self` \
 420                              argument is missing?")
 421         }
 422         ResolutionError::UnresolvedName(path, msg, context) => {
 423             let mut err = struct_span_err!(resolver.session,
 424                                            span,
 425                                            E0425,
 426                                            "unresolved name `{}`{}",
 427                                            path,
 428                                            msg);
 429
 430             match context {
 431                 UnresolvedNameContext::Other => { } // no help available
 432                 UnresolvedNameContext::PathIsMod(id) => {
 433                     let mut help_msg = String::new();
 434                     let parent_id = resolver.ast_map.get_parent_node(id);
 435                     if let Some(hir_map::Node::NodeExpr(e)) = resolver.ast_map.find(parent_id) {
 436                         match e.node {
 437                             ExprField(_, ident) => {
 438                                 help_msg = format!("To reference an item from the \
 439                                                     `{module}` module, use \
 440                                                     `{module}::{ident}`",
 441                                                    module = path,
 442                                                    ident = ident.node);
 443                             }
 444                             ExprMethodCall(ident, _, _) => {
 445                                 help_msg = format!("To call a function from the \
 446                                                     `{module}` module, use \
 447                                                     `{module}::{ident}(..)`",
 448                                                    module = path,
 449                                                    ident = ident.node);
 450                             }
 451                             ExprCall(_, _) => {
 452                                 help_msg = format!("No function corresponds to `{module}(..)`",
 453                                                    module = path);
 454                             }
 455                             _ => { } // no help available
 456                         }
 457                     } else {
 458                         help_msg = format!("Module `{module}` cannot be the value of an expression",
 459                                            module = path);
 460                     }
 461
 462                     if !help_msg.is_empty() {
 463                         err.fileline_help(span, &help_msg);
 464                     }
 465                 }
 466             }
 467             err
 468         }
 469         ResolutionError::UndeclaredLabel(name) => {
 470             struct_span_err!(resolver.session,
 471                              span,
 472                              E0426,
 473                              "use of undeclared label `{}`",
 474                              name)
 475         }
 476         ResolutionError::CannotUseRefBindingModeWith(descr) => {
 477             struct_span_err!(resolver.session,
 478                              span,
 479                              E0427,
 480                              "cannot use `ref` binding mode with {}",
 481                              descr)
 482         }
 483         ResolutionError::DuplicateDefinition(namespace, name) => {
 484             struct_span_err!(resolver.session,
 485                              span,
 486                              E0428,
 487                              "duplicate definition of {} `{}`",
 488                              namespace,
 489                              name)
 490         }
 491         ResolutionError::SelfImportsOnlyAllowedWithin => {
 492             struct_span_err!(resolver.session,
 493                              span,
 494                              E0429,
 495                              "{}",
 496                              "`self` imports are only allowed within a { } list")
 497         }
 498         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 499             struct_span_err!(resolver.session,
 500                              span,
 501                              E0430,
 502                              "`self` import can only appear once in the list")
 503         }
 504         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 505             struct_span_err!(resolver.session,
 506                              span,
 507                              E0431,
 508                              "`self` import can only appear in an import list with a \
 509                               non-empty prefix")
 510         }
 511         ResolutionError::UnresolvedImport(name) => {
 512             let msg = match name {
 513                 Some((n, p)) => format!("unresolved import `{}`{}", n, p),
 514                 None => "unresolved import".to_owned(),
 515             };
 516             struct_span_err!(resolver.session, span, E0432, "{}", msg)
 517         }
 518         ResolutionError::FailedToResolve(msg) => {
 519             struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg)
 520         }
 521         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 522             struct_span_err!(resolver.session,
 523                              span,
 524                              E0434,
 525                              "{}",
 526                              "can't capture dynamic environment in a fn item; use the || { ... } \
 527                               closure form instead")
 528         }
 529         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 530             struct_span_err!(resolver.session,
 531                              span,
 532                              E0435,
 533                              "attempt to use a non-constant value in a constant")
 534         }
 535     }
 536 }
 537
 538 #[derive(Copy, Clone)]
 539 struct BindingInfo {
 540     span: Span,
 541     binding_mode: BindingMode,
 542 }
 543
 544 // Map from the name in a pattern to its binding mode.
 545 type BindingMap = HashMap<Name, BindingInfo>;
 546
 547 #[derive(Copy, Clone, PartialEq)]
 548 enum PatternBindingMode {
 549     RefutableMode,
 550     LocalIrrefutableMode,
 551     ArgumentIrrefutableMode,
 552 }
 553
 554 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 555 pub enum Namespace {
 556     TypeNS,
 557     ValueNS,
 558 }
 559
 560 impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
 561     fn visit_nested_item(&mut self, item: hir::ItemId) {
 562         self.visit_item(self.ast_map.expect_item(item.id))
 563     }
 564     fn visit_item(&mut self, item: &Item) {
 565         execute_callback!(hir_map::Node::NodeItem(item), self);
 566         self.resolve_item(item);
 567     }
 568     fn visit_arm(&mut self, arm: &Arm) {
 569         self.resolve_arm(arm);
 570     }
 571     fn visit_block(&mut self, block: &Block) {
 572         execute_callback!(hir_map::Node::NodeBlock(block), self);
 573         self.resolve_block(block);
 574     }
 575     fn visit_expr(&mut self, expr: &Expr) {
 576         execute_callback!(hir_map::Node::NodeExpr(expr), self);
 577         self.resolve_expr(expr);
 578     }
 579     fn visit_local(&mut self, local: &Local) {
 580         execute_callback!(hir_map::Node::NodeLocal(&local.pat), self);
 581         self.resolve_local(local);
 582     }
 583     fn visit_ty(&mut self, ty: &Ty) {
 584         self.resolve_type(ty);
 585     }
 586     fn visit_generics(&mut self, generics: &Generics) {
 587         self.resolve_generics(generics);
 588     }
 589     fn visit_poly_trait_ref(&mut self, tref: &hir::PolyTraitRef, m: &hir::TraitBoundModifier) {
 590         match self.resolve_trait_reference(tref.trait_ref.ref_id, &tref.trait_ref.path, 0) {
 591             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
 592             Err(_) => {
 593                 // error already reported
 594                 self.record_def(tref.trait_ref.ref_id, err_path_resolution())
 595             }
 596         }
 597         intravisit::walk_poly_trait_ref(self, tref, m);
 598     }
 599     fn visit_variant(&mut self,
 600                      variant: &hir::Variant,
 601                      generics: &Generics,
 602                      item_id: ast::NodeId) {
 603         execute_callback!(hir_map::Node::NodeVariant(variant), self);
 604         if let Some(ref dis_expr) = variant.node.disr_expr {
 605             // resolve the discriminator expr as a constant
 606             self.with_constant_rib(|this| {
 607                 this.visit_expr(dis_expr);
 608             });
 609         }
 610
 611         // `intravisit::walk_variant` without the discriminant expression.
 612         self.visit_variant_data(&variant.node.data,
 613                                 variant.node.name,
 614                                 generics,
 615                                 item_id,
 616                                 variant.span);
 617     }
 618     fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem) {
 619         execute_callback!(hir_map::Node::NodeForeignItem(foreign_item), self);
 620         let type_parameters = match foreign_item.node {
 621             ForeignItemFn(_, ref generics) => {
 622                 HasTypeParameters(generics, FnSpace, ItemRibKind)
 623             }
 624             ForeignItemStatic(..) => NoTypeParameters,
 625         };
 626         self.with_type_parameter_rib(type_parameters, |this| {
 627             intravisit::walk_foreign_item(this, foreign_item);
 628         });
 629     }
 630     fn visit_fn(&mut self,
 631                 function_kind: FnKind<'v>,
 632                 declaration: &'v FnDecl,
 633                 block: &'v Block,
 634                 _: Span,
 635                 node_id: NodeId) {
 636         let rib_kind = match function_kind {
 637             FnKind::ItemFn(_, generics, _, _, _, _) => {
 638                 self.visit_generics(generics);
 639                 ItemRibKind
 640             }
 641             FnKind::Method(_, sig, _) => {
 642                 self.visit_generics(&sig.generics);
 643                 self.visit_explicit_self(&sig.explicit_self);
 644                 MethodRibKind
 645             }
 646             FnKind::Closure => ClosureRibKind(node_id),
 647         };
 648         self.resolve_function(rib_kind, declaration, block);
 649     }
 650 }
 651
 652 pub type ErrorMessage = Option<(Span, String)>;
 653
 654 #[derive(Clone, PartialEq, Eq)]
 655 pub enum ResolveResult<T> {
 656     Failed(ErrorMessage), // Failed to resolve the name, optional helpful error message.
 657     Indeterminate, // Couldn't determine due to unresolved globs.
 658     Success(T), // Successfully resolved the import.
 659 }
 660
 661 impl<T> ResolveResult<T> {
 662     fn and_then<U, F: FnOnce(T) -> ResolveResult<U>>(self, f: F) -> ResolveResult<U> {
 663         match self {
 664             Failed(msg) => Failed(msg),
 665             Indeterminate => Indeterminate,
 666             Success(t) => f(t),
 667         }
 668     }
 669
 670     fn success(self) -> Option<T> {
 671         match self {
 672             Success(t) => Some(t),
 673             _ => None,
 674         }
 675     }
 676 }
 677
 678 enum FallbackSuggestion {
 679     NoSuggestion,
 680     Field,
 681     Method,
 682     TraitItem,
 683     StaticMethod(String),
 684     TraitMethod(String),
 685 }
 686
 687 #[derive(Copy, Clone)]
 688 enum TypeParameters<'tcx, 'a> {
 689     NoTypeParameters,
 690     HasTypeParameters(// Type parameters.
 691                       &'a Generics,
 692
 693                       // Identifies the things that these parameters
 694                       // were declared on (type, fn, etc)
 695                       ParamSpace,
 696
 697                       // The kind of the rib used for type parameters.
 698                       RibKind<'tcx>),
 699 }
 700
 701 // The rib kind controls the translation of local
 702 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 703 #[derive(Copy, Clone, Debug)]
 704 enum RibKind<'a> {
 705     // No translation needs to be applied.
 706     NormalRibKind,
 707
 708     // We passed through a closure scope at the given node ID.
 709     // Translate upvars as appropriate.
 710     ClosureRibKind(NodeId /* func id */),
 711
 712     // We passed through an impl or trait and are now in one of its
 713     // methods. Allow references to ty params that impl or trait
 714     // binds. Disallow any other upvars (including other ty params that are
 715     // upvars).
 716     MethodRibKind,
 717
 718     // We passed through an item scope. Disallow upvars.
 719     ItemRibKind,
 720
 721     // We're in a constant item. Can't refer to dynamic stuff.
 722     ConstantItemRibKind,
 723
 724     // We passed through an anonymous module.
 725     AnonymousModuleRibKind(Module<'a>),
 726 }
 727
 728 #[derive(Copy, Clone)]
 729 enum UseLexicalScopeFlag {
 730     DontUseLexicalScope,
 731     UseLexicalScope,
 732 }
 733
 734 enum ModulePrefixResult<'a> {
 735     NoPrefixFound,
 736     PrefixFound(Module<'a>, usize),
 737 }
 738
 739 #[derive(Copy, Clone)]
 740 enum AssocItemResolveResult {
 741     /// Syntax such as `<T>::item`, which can't be resolved until type
 742     /// checking.
 743     TypecheckRequired,
 744     /// We should have been able to resolve the associated item.
 745     ResolveAttempt(Option<PathResolution>),
 746 }
 747
 748 #[derive(Copy, Clone)]
 749 enum BareIdentifierPatternResolution {
 750     FoundStructOrEnumVariant(Def, LastPrivate),
 751     FoundConst(Def, LastPrivate, Name),
 752     BareIdentifierPatternUnresolved,
 753 }
 754
 755 /// One local scope.
 756 #[derive(Debug)]
 757 struct Rib<'a> {
 758     bindings: HashMap<Name, DefLike>,
 759     kind: RibKind<'a>,
 760 }
 761
 762 impl<'a> Rib<'a> {
 763     fn new(kind: RibKind<'a>) -> Rib<'a> {
 764         Rib {
 765             bindings: HashMap::new(),
 766             kind: kind,
 767         }
 768     }
 769 }
 770
 771 /// A definition along with the index of the rib it was found on
 772 struct LocalDef {
 773     ribs: Option<(Namespace, usize)>,
 774     def: Def,
 775 }
 776
 777 impl LocalDef {
 778     fn from_def(def: Def) -> Self {
 779         LocalDef {
 780             ribs: None,
 781             def: def,
 782         }
 783     }
 784 }
 785
 786 /// The link from a module up to its nearest parent node.
 787 #[derive(Clone,Debug)]
 788 enum ParentLink<'a> {
 789     NoParentLink,
 790     ModuleParentLink(Module<'a>, Name),
 791     BlockParentLink(Module<'a>, NodeId),
 792 }
 793
 794 /// One node in the tree of modules.
 795 pub struct ModuleS<'a> {
 796     parent_link: ParentLink<'a>,
 797     def: Option<Def>,
 798     is_public: bool,
 799     is_extern_crate: bool,
 800
 801     resolutions: RefCell<HashMap<(Name, Namespace), NameResolution<'a>>>,
 802     imports: RefCell<Vec<ImportDirective>>,
 803
 804     // The module children of this node, including normal modules and anonymous modules.
 805     // Anonymous children are pseudo-modules that are implicitly created around items
 806     // contained within blocks.
 807     //
 808     // For example, if we have this:
 809     //
 810     //  fn f() {
 811     //      fn g() {
 812     //          ...
 813     //      }
 814     //  }
 815     //
 816     // There will be an anonymous module created around `g` with the ID of the
 817     // entry block for `f`.
 818     module_children: RefCell<NodeMap<Module<'a>>>,
 819
 820     shadowed_traits: RefCell<Vec<&'a NameBinding<'a>>>,
 821
 822     // The number of unresolved globs that this module exports.
 823     glob_count: Cell<usize>,
 824
 825     // The number of unresolved pub imports (both regular and globs) in this module
 826     pub_count: Cell<usize>,
 827
 828     // The number of unresolved pub glob imports in this module
 829     pub_glob_count: Cell<usize>,
 830
 831     // The index of the import we're resolving.
 832     resolved_import_count: Cell<usize>,
 833
 834     // Whether this module is populated. If not populated, any attempt to
 835     // access the children must be preceded with a
 836     // `populate_module_if_necessary` call.
 837     populated: Cell<bool>,
 838 }
 839
 840 pub type Module<'a> = &'a ModuleS<'a>;
 841
 842 impl<'a> ModuleS<'a> {
 843     fn new(parent_link: ParentLink<'a>, def: Option<Def>, external: bool, is_public: bool) -> Self {
 844         ModuleS {
 845             parent_link: parent_link,
 846             def: def,
 847             is_public: is_public,
 848             is_extern_crate: false,
 849             resolutions: RefCell::new(HashMap::new()),
 850             imports: RefCell::new(Vec::new()),
 851             module_children: RefCell::new(NodeMap()),
 852             shadowed_traits: RefCell::new(Vec::new()),
 853             glob_count: Cell::new(0),
 854             pub_count: Cell::new(0),
 855             pub_glob_count: Cell::new(0),
 856             resolved_import_count: Cell::new(0),
 857             populated: Cell::new(!external),
 858         }
 859     }
 860
 861     fn resolve_name(&self, name: Name, ns: Namespace, allow_private_imports: bool)
 862                     -> ResolveResult<&'a NameBinding<'a>> {
 863         let glob_count =
 864             if allow_private_imports { self.glob_count.get() } else { self.pub_glob_count.get() };
 865
 866         self.resolutions.borrow().get(&(name, ns)).cloned().unwrap_or_default().result(glob_count)
 867             .and_then(|binding| {
 868                 let allowed = allow_private_imports || !binding.is_import() || binding.is_public();
 869                 if allowed { Success(binding) } else { Failed(None) }
 870             })
 871     }
 872
 873     // Define the name or return the existing binding if there is a collision.
 874     fn try_define_child(&self, name: Name, ns: Namespace, binding: &'a NameBinding<'a>)
 875                         -> Result<(), &'a NameBinding<'a>> {
 876         let mut children = self.resolutions.borrow_mut();
 877         let resolution = children.entry((name, ns)).or_insert_with(Default::default);
 878
 879         // FIXME #31379: We can use methods from imported traits shadowed by non-import items
 880         if let Some(old_binding) = resolution.binding {
 881             if !old_binding.is_import() && binding.is_import() {
 882                 if let Some(Def::Trait(_)) = binding.def() {
 883                     self.shadowed_traits.borrow_mut().push(binding);
 884                 }
 885             }
 886         }
 887
 888         resolution.try_define(binding)
 889     }
 890
 891     fn increment_outstanding_references_for(&self, name: Name, ns: Namespace) {
 892         let mut children = self.resolutions.borrow_mut();
 893         children.entry((name, ns)).or_insert_with(Default::default).outstanding_references += 1;
 894     }
 895
 896     fn decrement_outstanding_references_for(&self, name: Name, ns: Namespace) {
 897         match self.resolutions.borrow_mut().get_mut(&(name, ns)).unwrap().outstanding_references {
 898             0 => panic!("No more outstanding references!"),
 899             ref mut outstanding_references => { *outstanding_references -= 1; }
 900         }
 901     }
 902
 903     fn for_each_child<F: FnMut(Name, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 904         for (&(name, ns), name_resolution) in self.resolutions.borrow().iter() {
 905             name_resolution.binding.map(|binding| f(name, ns, binding));
 906         }
 907     }
 908
 909     fn def_id(&self) -> Option<DefId> {
 910         self.def.as_ref().map(Def::def_id)
 911     }
 912
 913     fn is_normal(&self) -> bool {
 914         match self.def {
 915             Some(Def::Mod(_)) | Some(Def::ForeignMod(_)) => true,
 916             _ => false,
 917         }
 918     }
 919
 920     fn is_trait(&self) -> bool {
 921         match self.def {
 922             Some(Def::Trait(_)) => true,
 923             _ => false,
 924         }
 925     }
 926
 927     fn all_imports_resolved(&self) -> bool {
 928         if self.imports.borrow_state() == ::std::cell::BorrowState::Writing {
 929             // it is currently being resolved ! so nope
 930             false
 931         } else {
 932             self.imports.borrow().len() == self.resolved_import_count.get()
 933         }
 934     }
 935
 936     pub fn inc_glob_count(&self) {
 937         self.glob_count.set(self.glob_count.get() + 1);
 938     }
 939     pub fn dec_glob_count(&self) {
 940         assert!(self.glob_count.get() > 0);
 941         self.glob_count.set(self.glob_count.get() - 1);
 942     }
 943     pub fn inc_pub_count(&self) {
 944         self.pub_count.set(self.pub_count.get() + 1);
 945     }
 946     pub fn dec_pub_count(&self) {
 947         assert!(self.pub_count.get() > 0);
 948         self.pub_count.set(self.pub_count.get() - 1);
 949     }
 950     pub fn inc_pub_glob_count(&self) {
 951         self.pub_glob_count.set(self.pub_glob_count.get() + 1);
 952     }
 953     pub fn dec_pub_glob_count(&self) {
 954         assert!(self.pub_glob_count.get() > 0);
 955         self.pub_glob_count.set(self.pub_glob_count.get() - 1);
 956     }
 957 }
 958
 959 impl<'a> fmt::Debug for ModuleS<'a> {
 960     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 961         write!(f,
 962                "{:?}, {}",
 963                self.def,
 964                if self.is_public {
 965                    "public"
 966                } else {
 967                    "private"
 968                })
 969     }
 970 }
 971
 972 bitflags! {
 973     #[derive(Debug)]
 974     flags DefModifiers: u8 {
 975         // Enum variants are always considered `PUBLIC`, this is needed for `use Enum::Variant`
 976         // or `use Enum::*` to work on private enums.
 977         const PUBLIC     = 1 << 0,
 978         const IMPORTABLE = 1 << 1,
 979         // Variants are considered `PUBLIC`, but some of them live in private enums.
 980         // We need to track them to prohibit reexports like `pub use PrivEnum::Variant`.
 981         const PRIVATE_VARIANT = 1 << 2,
 982         const PRELUDE = 1 << 3,
 983         const GLOB_IMPORTED = 1 << 4,
 984     }
 985 }
 986
 987 // Records a possibly-private value, type, or module definition.
 988 #[derive(Debug)]
 989 pub struct NameBinding<'a> {
 990     modifiers: DefModifiers,
 991     kind: NameBindingKind<'a>,
 992     span: Option<Span>,
 993 }
 994
 995 #[derive(Debug)]
 996 enum NameBindingKind<'a> {
 997     Def(Def),
 998     Module(Module<'a>),
 999     Import {
1000         binding: &'a NameBinding<'a>,
1001         id: NodeId,
1002     },
1003 }
1004
1005 impl<'a> NameBinding<'a> {
1006     fn create_from_module(module: Module<'a>, span: Option<Span>) -> Self {
1007         let modifiers = if module.is_public {
1008             DefModifiers::PUBLIC
1009         } else {
1010             DefModifiers::empty()
1011         } | DefModifiers::IMPORTABLE;
1012
1013         NameBinding { modifiers: modifiers, kind: NameBindingKind::Module(module), span: span }
1014     }
1015
1016     fn module(&self) -> Option<Module<'a>> {
1017         match self.kind {
1018             NameBindingKind::Module(module) => Some(module),
1019             NameBindingKind::Def(_) => None,
1020             NameBindingKind::Import { binding, .. } => binding.module(),
1021         }
1022     }
1023
1024     fn def(&self) -> Option<Def> {
1025         match self.kind {
1026             NameBindingKind::Def(def) => Some(def),
1027             NameBindingKind::Module(module) => module.def,
1028             NameBindingKind::Import { binding, .. } => binding.def(),
1029         }
1030     }
1031
1032     fn defined_with(&self, modifiers: DefModifiers) -> bool {
1033         self.modifiers.contains(modifiers)
1034     }
1035
1036     fn is_public(&self) -> bool {
1037         self.defined_with(DefModifiers::PUBLIC)
1038     }
1039
1040     fn def_and_lp(&self) -> (Def, LastPrivate) {
1041         let def = self.def().unwrap();
1042         (def, LastMod(if self.is_public() { AllPublic } else { DependsOn(def.def_id()) }))
1043     }
1044
1045     fn is_extern_crate(&self) -> bool {
1046         self.module().map(|module| module.is_extern_crate).unwrap_or(false)
1047     }
1048
1049     fn is_import(&self) -> bool {
1050         match self.kind {
1051             NameBindingKind::Import { .. } => true,
1052             _ => false,
1053         }
1054     }
1055 }
1056
1057 /// Interns the names of the primitive types.
1058 struct PrimitiveTypeTable {
1059     primitive_types: HashMap<Name, PrimTy>,
1060 }
1061
1062 impl PrimitiveTypeTable {
1063     fn new() -> PrimitiveTypeTable {
1064         let mut table = PrimitiveTypeTable { primitive_types: HashMap::new() };
1065
1066         table.intern("bool", TyBool);
1067         table.intern("char", TyChar);
1068         table.intern("f32", TyFloat(FloatTy::F32));
1069         table.intern("f64", TyFloat(FloatTy::F64));
1070         table.intern("isize", TyInt(IntTy::Is));
1071         table.intern("i8", TyInt(IntTy::I8));
1072         table.intern("i16", TyInt(IntTy::I16));
1073         table.intern("i32", TyInt(IntTy::I32));
1074         table.intern("i64", TyInt(IntTy::I64));
1075         table.intern("str", TyStr);
1076         table.intern("usize", TyUint(UintTy::Us));
1077         table.intern("u8", TyUint(UintTy::U8));
1078         table.intern("u16", TyUint(UintTy::U16));
1079         table.intern("u32", TyUint(UintTy::U32));
1080         table.intern("u64", TyUint(UintTy::U64));
1081
1082         table
1083     }
1084
1085     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1086         self.primitive_types.insert(token::intern(string), primitive_type);
1087     }
1088 }
1089
1090 /// The main resolver class.
1091 pub struct Resolver<'a, 'tcx: 'a> {
1092     session: &'a Session,
1093
1094     ast_map: &'a hir_map::Map<'tcx>,
1095
1096     graph_root: Module<'a>,
1097
1098     trait_item_map: FnvHashMap<(Name, DefId), DefId>,
1099
1100     structs: FnvHashMap<DefId, Vec<Name>>,
1101
1102     // The number of imports that are currently unresolved.
1103     unresolved_imports: usize,
1104
1105     // The module that represents the current item scope.
1106     current_module: Module<'a>,
1107
1108     // The current set of local scopes, for values.
1109     // FIXME #4948: Reuse ribs to avoid allocation.
1110     value_ribs: Vec<Rib<'a>>,
1111
1112     // The current set of local scopes, for types.
1113     type_ribs: Vec<Rib<'a>>,
1114
1115     // The current set of local scopes, for labels.
1116     label_ribs: Vec<Rib<'a>>,
1117
1118     // The trait that the current context can refer to.
1119     current_trait_ref: Option<(DefId, TraitRef)>,
1120
1121     // The current self type if inside an impl (used for better errors).
1122     current_self_type: Option<Ty>,
1123
1124     // The idents for the primitive types.
1125     primitive_type_table: PrimitiveTypeTable,
1126
1127     def_map: RefCell<DefMap>,
1128     freevars: FreevarMap,
1129     freevars_seen: NodeMap<NodeMap<usize>>,
1130     export_map: ExportMap,
1131     trait_map: TraitMap,
1132     external_exports: ExternalExports,
1133
1134     // Whether or not to print error messages. Can be set to true
1135     // when getting additional info for error message suggestions,
1136     // so as to avoid printing duplicate errors
1137     emit_errors: bool,
1138
1139     make_glob_map: bool,
1140     // Maps imports to the names of items actually imported (this actually maps
1141     // all imports, but only glob imports are actually interesting).
1142     glob_map: GlobMap,
1143
1144     used_imports: HashSet<(NodeId, Namespace)>,
1145     used_crates: HashSet<CrateNum>,
1146
1147     // Callback function for intercepting walks
1148     callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>,
1149     // The intention is that the callback modifies this flag.
1150     // Once set, the resolver falls out of the walk, preserving the ribs.
1151     resolved: bool,
1152
1153     arenas: &'a ResolverArenas<'a>,
1154 }
1155
1156 pub struct ResolverArenas<'a> {
1157     modules: arena::TypedArena<ModuleS<'a>>,
1158     name_bindings: arena::TypedArena<NameBinding<'a>>,
1159 }
1160
1161 #[derive(PartialEq)]
1162 enum FallbackChecks {
1163     Everything,
1164     OnlyTraitAndStatics,
1165 }
1166
1167 impl<'a, 'tcx> Resolver<'a, 'tcx> {
1168     fn new(session: &'a Session,
1169            ast_map: &'a hir_map::Map<'tcx>,
1170            make_glob_map: MakeGlobMap,
1171            arenas: &'a ResolverArenas<'a>)
1172            -> Resolver<'a, 'tcx> {
1173         let root_def_id = ast_map.local_def_id(CRATE_NODE_ID);
1174         let graph_root = ModuleS::new(NoParentLink, Some(Def::Mod(root_def_id)), false, true);
1175         let graph_root = arenas.modules.alloc(graph_root);
1176
1177         Resolver {
1178             session: session,
1179
1180             ast_map: ast_map,
1181
1182             // The outermost module has def ID 0; this is not reflected in the
1183             // AST.
1184             graph_root: graph_root,
1185
1186             trait_item_map: FnvHashMap(),
1187             structs: FnvHashMap(),
1188
1189             unresolved_imports: 0,
1190
1191             current_module: graph_root,
1192             value_ribs: Vec::new(),
1193             type_ribs: Vec::new(),
1194             label_ribs: Vec::new(),
1195
1196             current_trait_ref: None,
1197             current_self_type: None,
1198
1199             primitive_type_table: PrimitiveTypeTable::new(),
1200
1201             def_map: RefCell::new(NodeMap()),
1202             freevars: NodeMap(),
1203             freevars_seen: NodeMap(),
1204             export_map: NodeMap(),
1205             trait_map: NodeMap(),
1206             used_imports: HashSet::new(),
1207             used_crates: HashSet::new(),
1208             external_exports: DefIdSet(),
1209
1210             emit_errors: true,
1211             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1212             glob_map: HashMap::new(),
1213
1214             callback: None,
1215             resolved: false,
1216
1217             arenas: arenas,
1218         }
1219     }
1220
1221     fn arenas() -> ResolverArenas<'a> {
1222         ResolverArenas {
1223             modules: arena::TypedArena::new(),
1224             name_bindings: arena::TypedArena::new(),
1225         }
1226     }
1227
1228     fn new_module(&self,
1229                   parent_link: ParentLink<'a>,
1230                   def: Option<Def>,
1231                   external: bool,
1232                   is_public: bool) -> Module<'a> {
1233         self.arenas.modules.alloc(ModuleS::new(parent_link, def, external, is_public))
1234     }
1235
1236     fn new_name_binding(&self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1237         self.arenas.name_bindings.alloc(name_binding)
1238     }
1239
1240     fn new_extern_crate_module(&self, parent_link: ParentLink<'a>, def: Def) -> Module<'a> {
1241         let mut module = ModuleS::new(parent_link, Some(def), false, true);
1242         module.is_extern_crate = true;
1243         self.arenas.modules.alloc(module)
1244     }
1245
1246     fn get_ribs<'b>(&'b mut self, ns: Namespace) -> &'b mut Vec<Rib<'a>> {
1247         match ns { ValueNS => &mut self.value_ribs, TypeNS => &mut self.type_ribs }
1248     }
1249
1250     #[inline]
1251     fn record_use(&mut self, name: Name, ns: Namespace, binding: &'a NameBinding<'a>) {
1252         // track extern crates for unused_extern_crate lint
1253         if let Some(DefId { krate, .. }) = binding.module().and_then(ModuleS::def_id) {
1254             self.used_crates.insert(krate);
1255         }
1256
1257         let import_id = match binding.kind {
1258             NameBindingKind::Import { id, .. } => id,
1259             _ => return,
1260         };
1261
1262         self.used_imports.insert((import_id, ns));
1263
1264         if !self.make_glob_map {
1265             return;
1266         }
1267         if self.glob_map.contains_key(&import_id) {
1268             self.glob_map.get_mut(&import_id).unwrap().insert(name);
1269             return;
1270         }
1271
1272         let mut new_set = HashSet::new();
1273         new_set.insert(name);
1274         self.glob_map.insert(import_id, new_set);
1275     }
1276
1277     fn get_trait_name(&self, did: DefId) -> Name {
1278         if let Some(node_id) = self.ast_map.as_local_node_id(did) {
1279             self.ast_map.expect_item(node_id).name
1280         } else {
1281             self.session.cstore.item_name(did)
1282         }
1283     }
1284
1285     /// Resolves the given module path from the given root `module_`.
1286     fn resolve_module_path_from_root(&mut self,
1287                                      module_: Module<'a>,
1288                                      module_path: &[Name],
1289                                      index: usize,
1290                                      span: Span,
1291                                      lp: LastPrivate)
1292                                      -> ResolveResult<(Module<'a>, LastPrivate)> {
1293         fn search_parent_externals<'a>(needle: Name, module: Module<'a>) -> Option<Module<'a>> {
1294             match module.resolve_name(needle, TypeNS, false) {
1295                 Success(binding) if binding.is_extern_crate() => Some(module),
1296                 _ => match module.parent_link {
1297                     ModuleParentLink(ref parent, _) => {
1298                         search_parent_externals(needle, parent)
1299                     }
1300                     _ => None,
1301                 },
1302             }
1303         }
1304
1305         let mut search_module = module_;
1306         let mut index = index;
1307         let module_path_len = module_path.len();
1308         let mut closest_private = lp;
1309
1310         // Resolve the module part of the path. This does not involve looking
1311         // upward though scope chains; we simply resolve names directly in
1312         // modules as we go.
1313         while index < module_path_len {
1314             let name = module_path[index];
1315             match self.resolve_name_in_module(search_module, name, TypeNS, false, true) {
1316                 Failed(None) => {
1317                     let segment_name = name.as_str();
1318                     let module_name = module_to_string(search_module);
1319                     let mut span = span;
1320                     let msg = if "???" == &module_name {
1321                         span.hi = span.lo + Pos::from_usize(segment_name.len());
1322
1323                         match search_parent_externals(name, &self.current_module) {
1324                             Some(module) => {
1325                                 let path_str = names_to_string(module_path);
1326                                 let target_mod_str = module_to_string(&module);
1327                                 let current_mod_str = module_to_string(&self.current_module);
1328
1329                                 let prefix = if target_mod_str == current_mod_str {
1330                                     "self::".to_string()
1331                                 } else {
1332                                     format!("{}::", target_mod_str)
1333                                 };
1334
1335                                 format!("Did you mean `{}{}`?", prefix, path_str)
1336                             }
1337                             None => format!("Maybe a missing `extern crate {}`?", segment_name),
1338                         }
1339                     } else {
1340                         format!("Could not find `{}` in `{}`", segment_name, module_name)
1341                     };
1342
1343                     return Failed(Some((span, msg)));
1344                 }
1345                 Failed(err) => return Failed(err),
1346                 Indeterminate => {
1347                     debug!("(resolving module path for import) module resolution is \
1348                             indeterminate: {}",
1349                            name);
1350                     return Indeterminate;
1351                 }
1352                 Success(binding) => {
1353                     // Check to see whether there are type bindings, and, if
1354                     // so, whether there is a module within.
1355                     if let Some(module_def) = binding.module() {
1356                         search_module = module_def;
1357
1358                         // Keep track of the closest private module used
1359                         // when resolving this import chain.
1360                         if !binding.is_public() {
1361                             if let Some(did) = search_module.def_id() {
1362                                 closest_private = LastMod(DependsOn(did));
1363                             }
1364                         }
1365                     } else {
1366                         let msg = format!("Not a module `{}`", name);
1367                         return Failed(Some((span, msg)));
1368                     }
1369                 }
1370             }
1371
1372             index += 1;
1373         }
1374
1375         return Success((search_module, closest_private));
1376     }
1377
1378     /// Attempts to resolve the module part of an import directive or path
1379     /// rooted at the given module.
1380     ///
1381     /// On success, returns the resolved module, and the closest *private*
1382     /// module found to the destination when resolving this path.
1383     fn resolve_module_path(&mut self,
1384                            module_: Module<'a>,
1385                            module_path: &[Name],
1386                            use_lexical_scope: UseLexicalScopeFlag,
1387                            span: Span)
1388                            -> ResolveResult<(Module<'a>, LastPrivate)> {
1389         if module_path.len() == 0 {
1390             return Success((self.graph_root, LastMod(AllPublic))) // Use the crate root
1391         }
1392
1393         debug!("(resolving module path for import) processing `{}` rooted at `{}`",
1394                names_to_string(module_path),
1395                module_to_string(&module_));
1396
1397         // Resolve the module prefix, if any.
1398         let module_prefix_result = self.resolve_module_prefix(module_, module_path);
1399
1400         let search_module;
1401         let start_index;
1402         let last_private;
1403         match module_prefix_result {
1404             Failed(None) => {
1405                 let mpath = names_to_string(module_path);
1406                 let mpath = &mpath[..];
1407                 match mpath.rfind(':') {
1408                     Some(idx) => {
1409                         let msg = format!("Could not find `{}` in `{}`",
1410                                           // idx +- 1 to account for the
1411                                           // colons on either side
1412                                           &mpath[idx + 1..],
1413                                           &mpath[..idx - 1]);
1414                         return Failed(Some((span, msg)));
1415                     }
1416                     None => {
1417                         return Failed(None);
1418                     }
1419                 }
1420             }
1421             Failed(err) => return Failed(err),
1422             Indeterminate => {
1423                 debug!("(resolving module path for import) indeterminate; bailing");
1424                 return Indeterminate;
1425             }
1426             Success(NoPrefixFound) => {
1427                 // There was no prefix, so we're considering the first element
1428                 // of the path. How we handle this depends on whether we were
1429                 // instructed to use lexical scope or not.
1430                 match use_lexical_scope {
1431                     DontUseLexicalScope => {
1432                         // This is a crate-relative path. We will start the
1433                         // resolution process at index zero.
1434                         search_module = self.graph_root;
1435                         start_index = 0;
1436                         last_private = LastMod(AllPublic);
1437                     }
1438                     UseLexicalScope => {
1439                         // This is not a crate-relative path. We resolve the
1440                         // first component of the path in the current lexical
1441                         // scope and then proceed to resolve below that.
1442                         match self.resolve_item_in_lexical_scope(module_,
1443                                                                  module_path[0],
1444                                                                  TypeNS,
1445                                                                  true) {
1446                             Failed(err) => return Failed(err),
1447                             Indeterminate => {
1448                                 debug!("(resolving module path for import) indeterminate; bailing");
1449                                 return Indeterminate;
1450                             }
1451                             Success(binding) => match binding.module() {
1452                                 Some(containing_module) => {
1453                                     search_module = containing_module;
1454                                     start_index = 1;
1455                                     last_private = LastMod(AllPublic);
1456                                 }
1457                                 None => return Failed(None),
1458                             }
1459                         }
1460                     }
1461                 }
1462             }
1463             Success(PrefixFound(ref containing_module, index)) => {
1464                 search_module = containing_module;
1465                 start_index = index;
1466                 last_private = LastMod(DependsOn(containing_module.def_id()
1467                                                                   .unwrap()));
1468             }
1469         }
1470
1471         self.resolve_module_path_from_root(search_module,
1472                                            module_path,
1473                                            start_index,
1474                                            span,
1475                                            last_private)
1476     }
1477
1478     /// Invariant: This must only be called during main resolution, not during
1479     /// import resolution.
1480     fn resolve_item_in_lexical_scope(&mut self,
1481                                      module_: Module<'a>,
1482                                      name: Name,
1483                                      namespace: Namespace,
1484                                      record_used: bool)
1485                                      -> ResolveResult<&'a NameBinding<'a>> {
1486         debug!("(resolving item in lexical scope) resolving `{}` in namespace {:?} in `{}`",
1487                name,
1488                namespace,
1489                module_to_string(&module_));
1490
1491         // Proceed up the scope chain looking for parent modules.
1492         let mut search_module = module_;
1493         loop {
1494             // Resolve the name in the parent module.
1495             match self.resolve_name_in_module(search_module, name, namespace, true, record_used) {
1496                 Failed(Some((span, msg))) => {
1497                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1498                 }
1499                 Failed(None) => (), // Continue up the search chain.
1500                 Indeterminate => {
1501                     // We couldn't see through the higher scope because of an
1502                     // unresolved import higher up. Bail.
1503
1504                     debug!("(resolving item in lexical scope) indeterminate higher scope; bailing");
1505                     return Indeterminate;
1506                 }
1507                 Success(binding) => {
1508                     // We found the module.
1509                     debug!("(resolving item in lexical scope) found name in module, done");
1510                     return Success(binding);
1511                 }
1512             }
1513
1514             // Go to the next parent.
1515             match search_module.parent_link {
1516                 NoParentLink => {
1517                     // No more parents. This module was unresolved.
1518                     debug!("(resolving item in lexical scope) unresolved module: no parent module");
1519                     return Failed(None);
1520                 }
1521                 ModuleParentLink(parent_module_node, _) => {
1522                     if search_module.is_normal() {
1523                         // We stop the search here.
1524                         debug!("(resolving item in lexical scope) unresolved module: not \
1525                                 searching through module parents");
1526                             return Failed(None);
1527                     } else {
1528                         search_module = parent_module_node;
1529                     }
1530                 }
1531                 BlockParentLink(parent_module_node, _) => {
1532                     search_module = parent_module_node;
1533                 }
1534             }
1535         }
1536     }
1537
1538     /// Returns the nearest normal module parent of the given module.
1539     fn get_nearest_normal_module_parent(&mut self, module_: Module<'a>) -> Option<Module<'a>> {
1540         let mut module_ = module_;
1541         loop {
1542             match module_.parent_link {
1543                 NoParentLink => return None,
1544                 ModuleParentLink(new_module, _) |
1545                 BlockParentLink(new_module, _) => {
1546                     let new_module = new_module;
1547                     if new_module.is_normal() {
1548                         return Some(new_module);
1549                     }
1550                     module_ = new_module;
1551                 }
1552             }
1553         }
1554     }
1555
1556     /// Returns the nearest normal module parent of the given module, or the
1557     /// module itself if it is a normal module.
1558     fn get_nearest_normal_module_parent_or_self(&mut self, module_: Module<'a>) -> Module<'a> {
1559         if module_.is_normal() {
1560             return module_;
1561         }
1562         match self.get_nearest_normal_module_parent(module_) {
1563             None => module_,
1564             Some(new_module) => new_module,
1565         }
1566     }
1567
1568     /// Resolves a "module prefix". A module prefix is one or both of (a) `self::`;
1569     /// (b) some chain of `super::`.
1570     /// grammar: (SELF MOD_SEP ) ? (SUPER MOD_SEP) *
1571     fn resolve_module_prefix(&mut self,
1572                              module_: Module<'a>,
1573                              module_path: &[Name])
1574                              -> ResolveResult<ModulePrefixResult<'a>> {
1575         // Start at the current module if we see `self` or `super`, or at the
1576         // top of the crate otherwise.
1577         let mut i = match &*module_path[0].as_str() {
1578             "self" => 1,
1579             "super" => 0,
1580             _ => return Success(NoPrefixFound),
1581         };
1582         let mut containing_module = self.get_nearest_normal_module_parent_or_self(module_);
1583
1584         // Now loop through all the `super`s we find.
1585         while i < module_path.len() && "super" == module_path[i].as_str() {
1586             debug!("(resolving module prefix) resolving `super` at {}",
1587                    module_to_string(&containing_module));
1588             match self.get_nearest_normal_module_parent(containing_module) {
1589                 None => return Failed(None),
1590                 Some(new_module) => {
1591                     containing_module = new_module;
1592                     i += 1;
1593                 }
1594             }
1595         }
1596
1597         debug!("(resolving module prefix) finished resolving prefix at {}",
1598                module_to_string(&containing_module));
1599
1600         return Success(PrefixFound(containing_module, i));
1601     }
1602
1603     /// Attempts to resolve the supplied name in the given module for the
1604     /// given namespace. If successful, returns the binding corresponding to
1605     /// the name.
1606     fn resolve_name_in_module(&mut self,
1607                               module: Module<'a>,
1608                               name: Name,
1609                               namespace: Namespace,
1610                               allow_private_imports: bool,
1611                               record_used: bool)
1612                               -> ResolveResult<&'a NameBinding<'a>> {
1613         debug!("(resolving name in module) resolving `{}` in `{}`", name, module_to_string(module));
1614
1615         build_reduced_graph::populate_module_if_necessary(self, module);
1616         module.resolve_name(name, namespace, allow_private_imports).and_then(|binding| {
1617             if record_used {
1618                 self.record_use(name, namespace, binding);
1619             }
1620             Success(binding)
1621         })
1622     }
1623
1624     fn report_unresolved_imports(&mut self, module_: Module<'a>) {
1625         let index = module_.resolved_import_count.get();
1626         let imports = module_.imports.borrow();
1627         let import_count = imports.len();
1628         if index != import_count {
1629             resolve_error(self,
1630                           (*imports)[index].span,
1631                           ResolutionError::UnresolvedImport(None));
1632         }
1633
1634         // Descend into children and anonymous children.
1635         for (_, module_) in module_.module_children.borrow().iter() {
1636             self.report_unresolved_imports(module_);
1637         }
1638     }
1639
1640     // AST resolution
1641     //
1642     // We maintain a list of value ribs and type ribs.
1643     //
1644     // Simultaneously, we keep track of the current position in the module
1645     // graph in the `current_module` pointer. When we go to resolve a name in
1646     // the value or type namespaces, we first look through all the ribs and
1647     // then query the module graph. When we resolve a name in the module
1648     // namespace, we can skip all the ribs (since nested modules are not
1649     // allowed within blocks in Rust) and jump straight to the current module
1650     // graph node.
1651     //
1652     // Named implementations are handled separately. When we find a method
1653     // call, we consult the module node to find all of the implementations in
1654     // scope. This information is lazily cached in the module node. We then
1655     // generate a fake "implementation scope" containing all the
1656     // implementations thus found, for compatibility with old resolve pass.
1657
1658     fn with_scope<F>(&mut self, id: NodeId, f: F)
1659         where F: FnOnce(&mut Resolver)
1660     {
1661         let orig_module = self.current_module;
1662
1663         // Move down in the graph.
1664         if let Some(module) = orig_module.module_children.borrow().get(&id) {
1665             self.current_module = module;
1666         }
1667
1668         f(self);
1669
1670         self.current_module = orig_module;
1671     }
1672
1673     /// Searches the current set of local scopes for labels.
1674     /// Stops after meeting a closure.
1675     fn search_label(&self, name: Name) -> Option<DefLike> {
1676         for rib in self.label_ribs.iter().rev() {
1677             match rib.kind {
1678                 NormalRibKind => {
1679                     // Continue
1680                 }
1681                 _ => {
1682                     // Do not resolve labels across function boundary
1683                     return None;
1684                 }
1685             }
1686             let result = rib.bindings.get(&name).cloned();
1687             if result.is_some() {
1688                 return result;
1689             }
1690         }
1691         None
1692     }
1693
1694     fn resolve_crate(&mut self, krate: &hir::Crate) {
1695         debug!("(resolving crate) starting");
1696
1697         intravisit::walk_crate(self, krate);
1698     }
1699
1700     fn check_if_primitive_type_name(&self, name: Name, span: Span) {
1701         if let Some(_) = self.primitive_type_table.primitive_types.get(&name) {
1702             span_err!(self.session,
1703                       span,
1704                       E0317,
1705                       "user-defined types or type parameters cannot shadow the primitive types");
1706         }
1707     }
1708
1709     fn resolve_item(&mut self, item: &Item) {
1710         let name = item.name;
1711
1712         debug!("(resolving item) resolving {}", name);
1713
1714         match item.node {
1715             ItemEnum(_, ref generics) |
1716             ItemTy(_, ref generics) |
1717             ItemStruct(_, ref generics) => {
1718                 self.check_if_primitive_type_name(name, item.span);
1719
1720                 self.with_type_parameter_rib(HasTypeParameters(generics, TypeSpace, ItemRibKind),
1721                                              |this| intravisit::walk_item(this, item));
1722             }
1723             ItemFn(_, _, _, _, ref generics, _) => {
1724                 self.with_type_parameter_rib(HasTypeParameters(generics, FnSpace, ItemRibKind),
1725                                              |this| intravisit::walk_item(this, item));
1726             }
1727
1728             ItemDefaultImpl(_, ref trait_ref) => {
1729                 self.with_optional_trait_ref(Some(trait_ref), |_, _| {});
1730             }
1731             ItemImpl(_, _, ref generics, ref opt_trait_ref, ref self_type, ref impl_items) => {
1732                 self.resolve_implementation(generics,
1733                                             opt_trait_ref,
1734                                             &self_type,
1735                                             item.id,
1736                                             impl_items);
1737             }
1738
1739             ItemTrait(_, ref generics, ref bounds, ref trait_items) => {
1740                 self.check_if_primitive_type_name(name, item.span);
1741
1742                 // Create a new rib for the trait-wide type parameters.
1743                 self.with_type_parameter_rib(HasTypeParameters(generics,
1744                                                                TypeSpace,
1745                                                                ItemRibKind),
1746                                              |this| {
1747                     let local_def_id = this.ast_map.local_def_id(item.id);
1748                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1749                         this.visit_generics(generics);
1750                         walk_list!(this, visit_ty_param_bound, bounds);
1751
1752                         for trait_item in trait_items {
1753                             match trait_item.node {
1754                                 hir::ConstTraitItem(_, ref default) => {
1755                                     // Only impose the restrictions of
1756                                     // ConstRibKind if there's an actual constant
1757                                     // expression in a provided default.
1758                                     if default.is_some() {
1759                                         this.with_constant_rib(|this| {
1760                                             intravisit::walk_trait_item(this, trait_item)
1761                                         });
1762                                     } else {
1763                                         intravisit::walk_trait_item(this, trait_item)
1764                                     }
1765                                 }
1766                                 hir::MethodTraitItem(ref sig, _) => {
1767                                     let type_parameters =
1768                                         HasTypeParameters(&sig.generics,
1769                                                           FnSpace,
1770                                                           MethodRibKind);
1771                                     this.with_type_parameter_rib(type_parameters, |this| {
1772                                         intravisit::walk_trait_item(this, trait_item)
1773                                     });
1774                                 }
1775                                 hir::TypeTraitItem(..) => {
1776                                     this.check_if_primitive_type_name(trait_item.name,
1777                                                                       trait_item.span);
1778                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1779                                         intravisit::walk_trait_item(this, trait_item)
1780                                     });
1781                                 }
1782                             };
1783                         }
1784                     });
1785                 });
1786             }
1787
1788             ItemMod(_) | ItemForeignMod(_) => {
1789                 self.with_scope(item.id, |this| {
1790                     intravisit::walk_item(this, item);
1791                 });
1792             }
1793
1794             ItemConst(..) | ItemStatic(..) => {
1795                 self.with_constant_rib(|this| {
1796                     intravisit::walk_item(this, item);
1797                 });
1798             }
1799
1800             ItemUse(ref view_path) => {
1801                 // check for imports shadowing primitive types
1802                 let check_rename = |this: &Self, id, name| {
1803                     match this.def_map.borrow().get(&id).map(|d| d.full_def()) {
1804                         Some(Def::Enum(..)) | Some(Def::TyAlias(..)) | Some(Def::Struct(..)) |
1805                         Some(Def::Trait(..)) | None => {
1806                             this.check_if_primitive_type_name(name, item.span);
1807                         }
1808                         _ => {}
1809                     }
1810                 };
1811
1812                 match view_path.node {
1813                     hir::ViewPathSimple(name, _) => {
1814                         check_rename(self, item.id, name);
1815                     }
1816                     hir::ViewPathList(ref prefix, ref items) => {
1817                         for item in items {
1818                             if let Some(name) = item.node.rename() {
1819                                 check_rename(self, item.node.id(), name);
1820                             }
1821                         }
1822
1823                         // Resolve prefix of an import with empty braces (issue #28388)
1824                         if items.is_empty() && !prefix.segments.is_empty() {
1825                             match self.resolve_crate_relative_path(prefix.span,
1826                                                                    &prefix.segments,
1827                                                                    TypeNS) {
1828                                 Some((def, lp)) =>
1829                                     self.record_def(item.id, PathResolution::new(def, lp, 0)),
1830                                 None => {
1831                                     resolve_error(self,
1832                                                   prefix.span,
1833                                                   ResolutionError::FailedToResolve(
1834                                                       &path_names_to_string(prefix, 0)));
1835                                     self.record_def(item.id, err_path_resolution());
1836                                 }
1837                             }
1838                         }
1839                     }
1840                     _ => {}
1841                 }
1842             }
1843
1844             ItemExternCrate(_) => {
1845                 // do nothing, these are just around to be encoded
1846             }
1847         }
1848     }
1849
1850     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1851         where F: FnOnce(&mut Resolver)
1852     {
1853         match type_parameters {
1854             HasTypeParameters(generics, space, rib_kind) => {
1855                 let mut function_type_rib = Rib::new(rib_kind);
1856                 let mut seen_bindings = HashSet::new();
1857                 for (index, type_parameter) in generics.ty_params.iter().enumerate() {
1858                     let name = type_parameter.name;
1859                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1860
1861                     if seen_bindings.contains(&name) {
1862                         resolve_error(self,
1863                                       type_parameter.span,
1864                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name));
1865                     }
1866                     seen_bindings.insert(name);
1867
1868                     // plain insert (no renaming)
1869                     function_type_rib.bindings
1870                                      .insert(name,
1871                                              DlDef(Def::TyParam(space,
1872                                                               index as u32,
1873                                                               self.ast_map
1874                                                                   .local_def_id(type_parameter.id),
1875                                                               name)));
1876                 }
1877                 self.type_ribs.push(function_type_rib);
1878             }
1879
1880             NoTypeParameters => {
1881                 // Nothing to do.
1882             }
1883         }
1884
1885         f(self);
1886
1887         match type_parameters {
1888             HasTypeParameters(..) => {
1889                 if !self.resolved {
1890                     self.type_ribs.pop();
1891                 }
1892             }
1893             NoTypeParameters => {}
1894         }
1895     }
1896
1897     fn with_label_rib<F>(&mut self, f: F)
1898         where F: FnOnce(&mut Resolver)
1899     {
1900         self.label_ribs.push(Rib::new(NormalRibKind));
1901         f(self);
1902         if !self.resolved {
1903             self.label_ribs.pop();
1904         }
1905     }
1906
1907     fn with_constant_rib<F>(&mut self, f: F)
1908         where F: FnOnce(&mut Resolver)
1909     {
1910         self.value_ribs.push(Rib::new(ConstantItemRibKind));
1911         self.type_ribs.push(Rib::new(ConstantItemRibKind));
1912         f(self);
1913         if !self.resolved {
1914             self.type_ribs.pop();
1915             self.value_ribs.pop();
1916         }
1917     }
1918
1919     fn resolve_function(&mut self, rib_kind: RibKind<'a>, declaration: &FnDecl, block: &Block) {
1920         // Create a value rib for the function.
1921         self.value_ribs.push(Rib::new(rib_kind));
1922
1923         // Create a label rib for the function.
1924         self.label_ribs.push(Rib::new(rib_kind));
1925
1926         // Add each argument to the rib.
1927         let mut bindings_list = HashMap::new();
1928         for argument in &declaration.inputs {
1929             self.resolve_pattern(&argument.pat, ArgumentIrrefutableMode, &mut bindings_list);
1930
1931             self.visit_ty(&argument.ty);
1932
1933             debug!("(resolving function) recorded argument");
1934         }
1935         intravisit::walk_fn_ret_ty(self, &declaration.output);
1936
1937         // Resolve the function body.
1938         self.visit_block(block);
1939
1940         debug!("(resolving function) leaving function");
1941
1942         if !self.resolved {
1943             self.label_ribs.pop();
1944             self.value_ribs.pop();
1945         }
1946     }
1947
1948     fn resolve_trait_reference(&mut self,
1949                                id: NodeId,
1950                                trait_path: &Path,
1951                                path_depth: usize)
1952                                -> Result<PathResolution, ()> {
1953         if let Some(path_res) = self.resolve_path(id, trait_path, path_depth, TypeNS, true) {
1954             if let Def::Trait(_) = path_res.base_def {
1955                 debug!("(resolving trait) found trait def: {:?}", path_res);
1956                 Ok(path_res)
1957             } else {
1958                 let mut err =
1959                     resolve_struct_error(self,
1960                                   trait_path.span,
1961                                   ResolutionError::IsNotATrait(&path_names_to_string(trait_path,
1962                                                                                       path_depth)));
1963
1964                 // If it's a typedef, give a note
1965                 if let Def::TyAlias(..) = path_res.base_def {
1966                     err.span_note(trait_path.span,
1967                                   "`type` aliases cannot be used for traits");
1968                 }
1969                 err.emit();
1970                 Err(())
1971             }
1972         } else {
1973             resolve_error(self,
1974                           trait_path.span,
1975                           ResolutionError::UndeclaredTraitName(&path_names_to_string(trait_path,
1976                                                                                       path_depth)));
1977             Err(())
1978         }
1979     }
1980
1981     fn resolve_generics(&mut self, generics: &Generics) {
1982         for type_parameter in generics.ty_params.iter() {
1983             self.check_if_primitive_type_name(type_parameter.name, type_parameter.span);
1984         }
1985         for predicate in &generics.where_clause.predicates {
1986             match predicate {
1987                 &hir::WherePredicate::BoundPredicate(_) |
1988                 &hir::WherePredicate::RegionPredicate(_) => {}
1989                 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
1990                     let path_res = self.resolve_path(eq_pred.id, &eq_pred.path, 0, TypeNS, true);
1991                     if let Some(PathResolution { base_def: Def::TyParam(..), .. }) = path_res {
1992                         self.record_def(eq_pred.id, path_res.unwrap());
1993                     } else {
1994                         resolve_error(self,
1995                                       eq_pred.span,
1996                                       ResolutionError::UndeclaredAssociatedType);
1997                         self.record_def(eq_pred.id, err_path_resolution());
1998                     }
1999                 }
2000             }
2001         }
2002         intravisit::walk_generics(self, generics);
2003     }
2004
2005     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
2006         where F: FnOnce(&mut Resolver) -> T
2007     {
2008         // Handle nested impls (inside fn bodies)
2009         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
2010         let result = f(self);
2011         self.current_self_type = previous_value;
2012         result
2013     }
2014
2015     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
2016         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
2017     {
2018         let mut new_val = None;
2019         let mut new_id = None;
2020         if let Some(trait_ref) = opt_trait_ref {
2021             if let Ok(path_res) = self.resolve_trait_reference(trait_ref.ref_id,
2022                                                                &trait_ref.path,
2023                                                                0) {
2024                 assert!(path_res.depth == 0);
2025                 self.record_def(trait_ref.ref_id, path_res);
2026                 new_val = Some((path_res.base_def.def_id(), trait_ref.clone()));
2027                 new_id = Some(path_res.base_def.def_id());
2028             } else {
2029                 self.record_def(trait_ref.ref_id, err_path_resolution());
2030             }
2031             intravisit::walk_trait_ref(self, trait_ref);
2032         }
2033         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2034         let result = f(self, new_id);
2035         self.current_trait_ref = original_trait_ref;
2036         result
2037     }
2038
2039     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
2040         where F: FnOnce(&mut Resolver)
2041     {
2042         let mut self_type_rib = Rib::new(NormalRibKind);
2043
2044         // plain insert (no renaming, types are not currently hygienic....)
2045         let name = special_names::type_self;
2046         self_type_rib.bindings.insert(name, DlDef(self_def));
2047         self.type_ribs.push(self_type_rib);
2048         f(self);
2049         if !self.resolved {
2050             self.type_ribs.pop();
2051         }
2052     }
2053
2054     fn resolve_implementation(&mut self,
2055                               generics: &Generics,
2056                               opt_trait_reference: &Option<TraitRef>,
2057                               self_type: &Ty,
2058                               item_id: NodeId,
2059                               impl_items: &[ImplItem]) {
2060         // If applicable, create a rib for the type parameters.
2061         self.with_type_parameter_rib(HasTypeParameters(generics,
2062                                                        TypeSpace,
2063                                                        ItemRibKind),
2064                                      |this| {
2065             // Resolve the type parameters.
2066             this.visit_generics(generics);
2067
2068             // Resolve the trait reference, if necessary.
2069             this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2070                 // Resolve the self type.
2071                 this.visit_ty(self_type);
2072
2073                 this.with_self_rib(Def::SelfTy(trait_id, Some((item_id, self_type.id))), |this| {
2074                     this.with_current_self_type(self_type, |this| {
2075                         for impl_item in impl_items {
2076                             match impl_item.node {
2077                                 hir::ImplItemKind::Const(..) => {
2078                                     // If this is a trait impl, ensure the const
2079                                     // exists in trait
2080                                     this.check_trait_item(impl_item.name,
2081                                                           impl_item.span,
2082                                         |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
2083                                     this.with_constant_rib(|this| {
2084                                         intravisit::walk_impl_item(this, impl_item);
2085                                     });
2086                                 }
2087                                 hir::ImplItemKind::Method(ref sig, _) => {
2088                                     // If this is a trait impl, ensure the method
2089                                     // exists in trait
2090                                     this.check_trait_item(impl_item.name,
2091                                                           impl_item.span,
2092                                         |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
2093
2094                                     // We also need a new scope for the method-
2095                                     // specific type parameters.
2096                                     let type_parameters =
2097                                         HasTypeParameters(&sig.generics,
2098                                                           FnSpace,
2099                                                           MethodRibKind);
2100                                     this.with_type_parameter_rib(type_parameters, |this| {
2101                                         intravisit::walk_impl_item(this, impl_item);
2102                                     });
2103                                 }
2104                                 hir::ImplItemKind::Type(ref ty) => {
2105                                     // If this is a trait impl, ensure the type
2106                                     // exists in trait
2107                                     this.check_trait_item(impl_item.name,
2108                                                           impl_item.span,
2109                                         |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
2110
2111                                     this.visit_ty(ty);
2112                                 }
2113                             }
2114                         }
2115                     });
2116                 });
2117             });
2118         });
2119     }
2120
2121     fn check_trait_item<F>(&self, name: Name, span: Span, err: F)
2122         where F: FnOnce(Name, &str) -> ResolutionError
2123     {
2124         // If there is a TraitRef in scope for an impl, then the method must be in the
2125         // trait.
2126         if let Some((did, ref trait_ref)) = self.current_trait_ref {
2127             if !self.trait_item_map.contains_key(&(name, did)) {
2128                 let path_str = path_names_to_string(&trait_ref.path, 0);
2129                 resolve_error(self, span, err(name, &path_str));
2130             }
2131         }
2132     }
2133
2134     fn resolve_local(&mut self, local: &Local) {
2135         // Resolve the type.
2136         walk_list!(self, visit_ty, &local.ty);
2137
2138         // Resolve the initializer.
2139         walk_list!(self, visit_expr, &local.init);
2140
2141         // Resolve the pattern.
2142         self.resolve_pattern(&local.pat, LocalIrrefutableMode, &mut HashMap::new());
2143     }
2144
2145     // build a map from pattern identifiers to binding-info's.
2146     // this is done hygienically. This could arise for a macro
2147     // that expands into an or-pattern where one 'x' was from the
2148     // user and one 'x' came from the macro.
2149     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2150         let mut result = HashMap::new();
2151         pat_bindings(&self.def_map, pat, |binding_mode, _id, sp, path1| {
2152             let name = path1.node;
2153             result.insert(name,
2154                           BindingInfo {
2155                               span: sp,
2156                               binding_mode: binding_mode,
2157                           });
2158         });
2159         return result;
2160     }
2161
2162     // check that all of the arms in an or-pattern have exactly the
2163     // same set of bindings, with the same binding modes for each.
2164     fn check_consistent_bindings(&mut self, arm: &Arm) {
2165         if arm.pats.is_empty() {
2166             return;
2167         }
2168         let map_0 = self.binding_mode_map(&arm.pats[0]);
2169         for (i, p) in arm.pats.iter().enumerate() {
2170             let map_i = self.binding_mode_map(&p);
2171
2172             for (&key, &binding_0) in &map_0 {
2173                 match map_i.get(&key) {
2174                     None => {
2175                         resolve_error(self,
2176                                       p.span,
2177                                       ResolutionError::VariableNotBoundInPattern(key, i + 1));
2178                     }
2179                     Some(binding_i) => {
2180                         if binding_0.binding_mode != binding_i.binding_mode {
2181                             resolve_error(self,
2182                                           binding_i.span,
2183                                           ResolutionError::VariableBoundWithDifferentMode(key,
2184                                                                                           i + 1));
2185                         }
2186                     }
2187                 }
2188             }
2189
2190             for (&key, &binding) in &map_i {
2191                 if !map_0.contains_key(&key) {
2192                     resolve_error(self,
2193                                   binding.span,
2194                                   ResolutionError::VariableNotBoundInParentPattern(key, i + 1));
2195                 }
2196             }
2197         }
2198     }
2199
2200     fn resolve_arm(&mut self, arm: &Arm) {
2201         self.value_ribs.push(Rib::new(NormalRibKind));
2202
2203         let mut bindings_list = HashMap::new();
2204         for pattern in &arm.pats {
2205             self.resolve_pattern(&pattern, RefutableMode, &mut bindings_list);
2206         }
2207
2208         // This has to happen *after* we determine which
2209         // pat_idents are variants
2210         self.check_consistent_bindings(arm);
2211
2212         walk_list!(self, visit_expr, &arm.guard);
2213         self.visit_expr(&arm.body);
2214
2215         if !self.resolved {
2216             self.value_ribs.pop();
2217         }
2218     }
2219
2220     fn resolve_block(&mut self, block: &Block) {
2221         debug!("(resolving block) entering block");
2222         // Move down in the graph, if there's an anonymous module rooted here.
2223         let orig_module = self.current_module;
2224         let anonymous_module =
2225             orig_module.module_children.borrow().get(&block.id).map(|module| *module);
2226
2227         if let Some(anonymous_module) = anonymous_module {
2228             debug!("(resolving block) found anonymous module, moving down");
2229             self.value_ribs.push(Rib::new(AnonymousModuleRibKind(anonymous_module)));
2230             self.type_ribs.push(Rib::new(AnonymousModuleRibKind(anonymous_module)));
2231             self.current_module = anonymous_module;
2232         } else {
2233             self.value_ribs.push(Rib::new(NormalRibKind));
2234         }
2235
2236         // Descend into the block.
2237         intravisit::walk_block(self, block);
2238
2239         // Move back up.
2240         if !self.resolved {
2241             self.current_module = orig_module;
2242             self.value_ribs.pop();
2243             if let Some(_) = anonymous_module {
2244                 self.type_ribs.pop();
2245             }
2246         }
2247         debug!("(resolving block) leaving block");
2248     }
2249
2250     fn resolve_type(&mut self, ty: &Ty) {
2251         match ty.node {
2252             TyPath(ref maybe_qself, ref path) => {
2253                 let resolution = match self.resolve_possibly_assoc_item(ty.id,
2254                                                                         maybe_qself.as_ref(),
2255                                                                         path,
2256                                                                         TypeNS,
2257                                                                         true) {
2258                     // `<T>::a::b::c` is resolved by typeck alone.
2259                     TypecheckRequired => {
2260                         // Resolve embedded types.
2261                         intravisit::walk_ty(self, ty);
2262                         return;
2263                     }
2264                     ResolveAttempt(resolution) => resolution,
2265                 };
2266
2267                 // This is a path in the type namespace. Walk through scopes
2268                 // looking for it.
2269                 match resolution {
2270                     Some(def) => {
2271                         // Write the result into the def map.
2272                         debug!("(resolving type) writing resolution for `{}` (id {}) = {:?}",
2273                                path_names_to_string(path, 0),
2274                                ty.id,
2275                                def);
2276                         self.record_def(ty.id, def);
2277                     }
2278                     None => {
2279                         self.record_def(ty.id, err_path_resolution());
2280
2281                         // Keep reporting some errors even if they're ignored above.
2282                         self.resolve_path(ty.id, path, 0, TypeNS, true);
2283
2284                         let kind = if maybe_qself.is_some() {
2285                             "associated type"
2286                         } else {
2287                             "type name"
2288                         };
2289
2290                         let self_type_name = special_idents::type_self.name;
2291                         let is_invalid_self_type_name = path.segments.len() > 0 &&
2292                                                         maybe_qself.is_none() &&
2293                                                         path.segments[0].identifier.name ==
2294                                                         self_type_name;
2295                         if is_invalid_self_type_name {
2296                             resolve_error(self,
2297                                           ty.span,
2298                                           ResolutionError::SelfUsedOutsideImplOrTrait);
2299                         } else {
2300                             resolve_error(self,
2301                                           ty.span,
2302                                           ResolutionError::UseOfUndeclared(
2303                                                                     kind,
2304                                                                     &path_names_to_string(path,
2305                                                                                            0))
2306                                          );
2307                         }
2308                     }
2309                 }
2310             }
2311             _ => {}
2312         }
2313         // Resolve embedded types.
2314         intravisit::walk_ty(self, ty);
2315     }
2316
2317     fn resolve_pattern(&mut self,
2318                        pattern: &Pat,
2319                        mode: PatternBindingMode,
2320                        // Maps idents to the node ID for the (outermost)
2321                        // pattern that binds them
2322                        bindings_list: &mut HashMap<Name, NodeId>) {
2323         let pat_id = pattern.id;
2324         walk_pat(pattern, |pattern| {
2325             match pattern.node {
2326                 PatIdent(binding_mode, ref path1, ref at_rhs) => {
2327                     // The meaning of PatIdent with no type parameters
2328                     // depends on whether an enum variant or unit-like struct
2329                     // with that name is in scope. The probing lookup has to
2330                     // be careful not to emit spurious errors. Only matching
2331                     // patterns (match) can match nullary variants or
2332                     // unit-like structs. For binding patterns (let
2333                     // and the LHS of @-patterns), matching such a value is
2334                     // simply disallowed (since it's rarely what you want).
2335                     let const_ok = mode == RefutableMode && at_rhs.is_none();
2336
2337                     let ident = path1.node;
2338                     let renamed = ident.name;
2339
2340                     match self.resolve_bare_identifier_pattern(ident.unhygienic_name,
2341                                                                pattern.span) {
2342                         FoundStructOrEnumVariant(def, lp) if const_ok => {
2343                             debug!("(resolving pattern) resolving `{}` to struct or enum variant",
2344                                    renamed);
2345
2346                             self.enforce_default_binding_mode(pattern,
2347                                                               binding_mode,
2348                                                               "an enum variant");
2349                             self.record_def(pattern.id,
2350                                             PathResolution {
2351                                                 base_def: def,
2352                                                 last_private: lp,
2353                                                 depth: 0,
2354                                             });
2355                         }
2356                         FoundStructOrEnumVariant(..) => {
2357                             resolve_error(
2358                                 self,
2359                                 pattern.span,
2360                                 ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(
2361                                     renamed)
2362                             );
2363                             self.record_def(pattern.id, err_path_resolution());
2364                         }
2365                         FoundConst(def, lp, _) if const_ok => {
2366                             debug!("(resolving pattern) resolving `{}` to constant", renamed);
2367
2368                             self.enforce_default_binding_mode(pattern, binding_mode, "a constant");
2369                             self.record_def(pattern.id,
2370                                             PathResolution {
2371                                                 base_def: def,
2372                                                 last_private: lp,
2373                                                 depth: 0,
2374                                             });
2375                         }
2376                         FoundConst(def, _, name) => {
2377                             resolve_error(
2378                                 self,
2379                                 pattern.span,
2380                                 ResolutionError::OnlyIrrefutablePatternsAllowedHere(def.def_id(),
2381                                                                                     name)
2382                             );
2383                             self.record_def(pattern.id, err_path_resolution());
2384                         }
2385                         BareIdentifierPatternUnresolved => {
2386                             debug!("(resolving pattern) binding `{}`", renamed);
2387
2388                             let def_id = self.ast_map.local_def_id(pattern.id);
2389                             let def = Def::Local(def_id, pattern.id);
2390
2391                             // Record the definition so that later passes
2392                             // will be able to distinguish variants from
2393                             // locals in patterns.
2394
2395                             self.record_def(pattern.id,
2396                                             PathResolution {
2397                                                 base_def: def,
2398                                                 last_private: LastMod(AllPublic),
2399                                                 depth: 0,
2400                                             });
2401
2402                             // Add the binding to the local ribs, if it
2403                             // doesn't already exist in the bindings list. (We
2404                             // must not add it if it's in the bindings list
2405                             // because that breaks the assumptions later
2406                             // passes make about or-patterns.)
2407                             if !bindings_list.contains_key(&renamed) {
2408                                 let this = &mut *self;
2409                                 let last_rib = this.value_ribs.last_mut().unwrap();
2410                                 last_rib.bindings.insert(renamed, DlDef(def));
2411                                 bindings_list.insert(renamed, pat_id);
2412                             } else if mode == ArgumentIrrefutableMode &&
2413                                bindings_list.contains_key(&renamed) {
2414                                 // Forbid duplicate bindings in the same
2415                                 // parameter list.
2416                                 resolve_error(
2417                                     self,
2418                                     pattern.span,
2419                                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2420                                         &ident.name.as_str())
2421                                 );
2422                             } else if bindings_list.get(&renamed) == Some(&pat_id) {
2423                                 // Then this is a duplicate variable in the
2424                                 // same disjunction, which is an error.
2425                                 resolve_error(
2426                                     self,
2427                                     pattern.span,
2428                                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2429                                         &ident.name.as_str())
2430                                 );
2431                             }
2432                             // Else, not bound in the same pattern: do
2433                             // nothing.
2434                         }
2435                     }
2436                 }
2437
2438                 PatEnum(ref path, _) => {
2439                     // This must be an enum variant, struct or const.
2440                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2441                                                                             None,
2442                                                                             path,
2443                                                                             ValueNS,
2444                                                                             false) {
2445                         // The below shouldn't happen because all
2446                         // qualified paths should be in PatQPath.
2447                         TypecheckRequired =>
2448                             self.session.span_bug(path.span,
2449                                                   "resolve_possibly_assoc_item claimed
2450                                      \
2451                                                    that a path in PatEnum requires typecheck
2452                                      \
2453                                                    to resolve, but qualified paths should be
2454                                      \
2455                                                    PatQPath"),
2456                         ResolveAttempt(resolution) => resolution,
2457                     };
2458                     if let Some(path_res) = resolution {
2459                         match path_res.base_def {
2460                             Def::Struct(..) if path_res.depth == 0 => {
2461                                 self.record_def(pattern.id, path_res);
2462                             }
2463                             Def::Variant(..) | Def::Const(..) => {
2464                                 self.record_def(pattern.id, path_res);
2465                             }
2466                             Def::Static(..) => {
2467                                 resolve_error(&self,
2468                                               path.span,
2469                                               ResolutionError::StaticVariableReference);
2470                                 self.record_def(pattern.id, err_path_resolution());
2471                             }
2472                             _ => {
2473                                 // If anything ends up here entirely resolved,
2474                                 // it's an error. If anything ends up here
2475                                 // partially resolved, that's OK, because it may
2476                                 // be a `T::CONST` that typeck will resolve.
2477                                 if path_res.depth == 0 {
2478                                     resolve_error(
2479                                         self,
2480                                         path.span,
2481                                         ResolutionError::NotAnEnumVariantStructOrConst(
2482                                             &path.segments
2483                                                  .last()
2484                                                  .unwrap()
2485                                                  .identifier
2486                                                  .name
2487                                                  .as_str())
2488                                     );
2489                                     self.record_def(pattern.id, err_path_resolution());
2490                                 } else {
2491                                     let const_name = path.segments
2492                                                          .last()
2493                                                          .unwrap()
2494                                                          .identifier
2495                                                          .name;
2496                                     let traits = self.get_traits_containing_item(const_name);
2497                                     self.trait_map.insert(pattern.id, traits);
2498                                     self.record_def(pattern.id, path_res);
2499                                 }
2500                             }
2501                         }
2502                     } else {
2503                         resolve_error(
2504                             self,
2505                             path.span,
2506                             ResolutionError::UnresolvedEnumVariantStructOrConst(
2507                                 &path.segments.last().unwrap().identifier.name.as_str())
2508                         );
2509                         self.record_def(pattern.id, err_path_resolution());
2510                     }
2511                     intravisit::walk_path(self, path);
2512                 }
2513
2514                 PatQPath(ref qself, ref path) => {
2515                     // Associated constants only.
2516                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2517                                                                             Some(qself),
2518                                                                             path,
2519                                                                             ValueNS,
2520                                                                             false) {
2521                         TypecheckRequired => {
2522                             // All `<T>::CONST` should end up here, and will
2523                             // require use of the trait map to resolve
2524                             // during typechecking.
2525                             let const_name = path.segments
2526                                                  .last()
2527                                                  .unwrap()
2528                                                  .identifier
2529                                                  .name;
2530                             let traits = self.get_traits_containing_item(const_name);
2531                             self.trait_map.insert(pattern.id, traits);
2532                             intravisit::walk_pat(self, pattern);
2533                             return true;
2534                         }
2535                         ResolveAttempt(resolution) => resolution,
2536                     };
2537                     if let Some(path_res) = resolution {
2538                         match path_res.base_def {
2539                             // All `<T as Trait>::CONST` should end up here, and
2540                             // have the trait already selected.
2541                             Def::AssociatedConst(..) => {
2542                                 self.record_def(pattern.id, path_res);
2543                             }
2544                             _ => {
2545                                 resolve_error(
2546                                     self,
2547                                     path.span,
2548                                     ResolutionError::NotAnAssociatedConst(
2549                                         &path.segments.last().unwrap().identifier.name.as_str()
2550                                     )
2551                                 );
2552                                 self.record_def(pattern.id, err_path_resolution());
2553                             }
2554                         }
2555                     } else {
2556                         resolve_error(self,
2557                                       path.span,
2558                                       ResolutionError::UnresolvedAssociatedConst(&path.segments
2559                                                                                       .last()
2560                                                                                       .unwrap()
2561                                                                                       .identifier
2562                                                                                       .name
2563                                                                                       .as_str()));
2564                         self.record_def(pattern.id, err_path_resolution());
2565                     }
2566                     intravisit::walk_pat(self, pattern);
2567                 }
2568
2569                 PatStruct(ref path, _, _) => {
2570                     match self.resolve_path(pat_id, path, 0, TypeNS, false) {
2571                         Some(definition) => {
2572                             self.record_def(pattern.id, definition);
2573                         }
2574                         result => {
2575                             debug!("(resolving pattern) didn't find struct def: {:?}", result);
2576                             resolve_error(
2577                                 self,
2578                                 path.span,
2579                                 ResolutionError::DoesNotNameAStruct(
2580                                     &path_names_to_string(path, 0))
2581                             );
2582                             self.record_def(pattern.id, err_path_resolution());
2583                         }
2584                     }
2585                     intravisit::walk_path(self, path);
2586                 }
2587
2588                 PatLit(_) | PatRange(..) => {
2589                     intravisit::walk_pat(self, pattern);
2590                 }
2591
2592                 _ => {
2593                     // Nothing to do.
2594                 }
2595             }
2596             true
2597         });
2598     }
2599
2600     fn resolve_bare_identifier_pattern(&mut self,
2601                                        name: Name,
2602                                        span: Span)
2603                                        -> BareIdentifierPatternResolution {
2604         let module = self.current_module;
2605         match self.resolve_item_in_lexical_scope(module, name, ValueNS, true) {
2606             Success(binding) => {
2607                 debug!("(resolve bare identifier pattern) succeeded in finding {} at {:?}",
2608                        name,
2609                        binding);
2610                 match binding.def() {
2611                     None => {
2612                         panic!("resolved name in the value namespace to a set of name bindings \
2613                                 with no def?!");
2614                     }
2615                     // For the two success cases, this lookup can be
2616                     // considered as not having a private component because
2617                     // the lookup happened only within the current module.
2618                     Some(def @ Def::Variant(..)) | Some(def @ Def::Struct(..)) => {
2619                         return FoundStructOrEnumVariant(def, LastMod(AllPublic));
2620                     }
2621                     Some(def @ Def::Const(..)) | Some(def @ Def::AssociatedConst(..)) => {
2622                         return FoundConst(def, LastMod(AllPublic), name);
2623                     }
2624                     Some(Def::Static(..)) => {
2625                         resolve_error(self, span, ResolutionError::StaticVariableReference);
2626                         return BareIdentifierPatternUnresolved;
2627                     }
2628                     _ => return BareIdentifierPatternUnresolved
2629                 }
2630             }
2631
2632             Indeterminate => return BareIdentifierPatternUnresolved,
2633             Failed(err) => {
2634                 match err {
2635                     Some((span, msg)) => {
2636                         resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2637                     }
2638                     None => (),
2639                 }
2640
2641                 debug!("(resolve bare identifier pattern) failed to find {}", name);
2642                 return BareIdentifierPatternUnresolved;
2643             }
2644         }
2645     }
2646
2647     /// Handles paths that may refer to associated items
2648     fn resolve_possibly_assoc_item(&mut self,
2649                                    id: NodeId,
2650                                    maybe_qself: Option<&hir::QSelf>,
2651                                    path: &Path,
2652                                    namespace: Namespace,
2653                                    check_ribs: bool)
2654                                    -> AssocItemResolveResult {
2655         let max_assoc_types;
2656
2657         match maybe_qself {
2658             Some(qself) => {
2659                 if qself.position == 0 {
2660                     return TypecheckRequired;
2661                 }
2662                 max_assoc_types = path.segments.len() - qself.position;
2663                 // Make sure the trait is valid.
2664                 let _ = self.resolve_trait_reference(id, path, max_assoc_types);
2665             }
2666             None => {
2667                 max_assoc_types = path.segments.len();
2668             }
2669         }
2670
2671         let mut resolution = self.with_no_errors(|this| {
2672             this.resolve_path(id, path, 0, namespace, check_ribs)
2673         });
2674         for depth in 1..max_assoc_types {
2675             if resolution.is_some() {
2676                 break;
2677             }
2678             self.with_no_errors(|this| {
2679                 resolution = this.resolve_path(id, path, depth, TypeNS, true);
2680             });
2681         }
2682         if let Some(Def::Mod(_)) = resolution.map(|r| r.base_def) {
2683             // A module is not a valid type or value.
2684             resolution = None;
2685         }
2686         ResolveAttempt(resolution)
2687     }
2688
2689     /// If `check_ribs` is true, checks the local definitions first; i.e.
2690     /// doesn't skip straight to the containing module.
2691     /// Skips `path_depth` trailing segments, which is also reflected in the
2692     /// returned value. See `middle::def::PathResolution` for more info.
2693     pub fn resolve_path(&mut self,
2694                         id: NodeId,
2695                         path: &Path,
2696                         path_depth: usize,
2697                         namespace: Namespace,
2698                         check_ribs: bool)
2699                         -> Option<PathResolution> {
2700         let span = path.span;
2701         let segments = &path.segments[..path.segments.len() - path_depth];
2702
2703         let mk_res = |(def, lp)| PathResolution::new(def, lp, path_depth);
2704
2705         if path.global {
2706             let def = self.resolve_crate_relative_path(span, segments, namespace);
2707             return def.map(mk_res);
2708         }
2709
2710         // Try to find a path to an item in a module.
2711         let last_ident = segments.last().unwrap().identifier;
2712         if segments.len() <= 1 {
2713             let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, true);
2714             return unqualified_def.and_then(|def| self.adjust_local_def(def, span))
2715                                   .map(|def| {
2716                                       PathResolution::new(def, LastMod(AllPublic), path_depth)
2717                                   });
2718         }
2719
2720         let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, false);
2721         let def = self.resolve_module_relative_path(span, segments, namespace);
2722         match (def, unqualified_def) {
2723             (Some((ref d, _)), Some(ref ud)) if *d == ud.def => {
2724                 self.session
2725                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
2726                               id,
2727                               span,
2728                               "unnecessary qualification".to_string());
2729             }
2730             _ => {}
2731         }
2732
2733         def.map(mk_res)
2734     }
2735
2736     // Resolve a single identifier
2737     fn resolve_identifier(&mut self,
2738                           identifier: hir::Ident,
2739                           namespace: Namespace,
2740                           check_ribs: bool,
2741                           record_used: bool)
2742                           -> Option<LocalDef> {
2743         if identifier.name == special_idents::invalid.name {
2744             return Some(LocalDef::from_def(Def::Err));
2745         }
2746
2747         // First, check to see whether the name is a primitive type.
2748         if namespace == TypeNS {
2749             if let Some(&prim_ty) = self.primitive_type_table
2750                                         .primitive_types
2751                                         .get(&identifier.unhygienic_name) {
2752                 return Some(LocalDef::from_def(Def::PrimTy(prim_ty)));
2753             }
2754         }
2755
2756         if check_ribs {
2757             if let Some(def) = self.resolve_identifier_in_local_ribs(identifier, namespace) {
2758                 return Some(def);
2759             }
2760         }
2761
2762         // Check the items.
2763         let module = self.current_module;
2764         let name = identifier.unhygienic_name;
2765         match self.resolve_item_in_lexical_scope(module, name, namespace, record_used) {
2766             Success(binding) => binding.def().map(LocalDef::from_def),
2767             Failed(Some((span, msg))) => {
2768                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2769                 None
2770             }
2771             _ => None,
2772         }
2773     }
2774
2775     // Resolve a local definition, potentially adjusting for closures.
2776     fn adjust_local_def(&mut self, local_def: LocalDef, span: Span) -> Option<Def> {
2777         let ribs = match local_def.ribs {
2778             Some((TypeNS, i)) => &self.type_ribs[i + 1..],
2779             Some((ValueNS, i)) => &self.value_ribs[i + 1..],
2780             _ => &[] as &[_],
2781         };
2782         let mut def = local_def.def;
2783         match def {
2784             Def::Upvar(..) => {
2785                 self.session.span_bug(span, &format!("unexpected {:?} in bindings", def))
2786             }
2787             Def::Local(_, node_id) => {
2788                 for rib in ribs {
2789                     match rib.kind {
2790                         NormalRibKind | AnonymousModuleRibKind(..) => {
2791                             // Nothing to do. Continue.
2792                         }
2793                         ClosureRibKind(function_id) => {
2794                             let prev_def = def;
2795                             let node_def_id = self.ast_map.local_def_id(node_id);
2796
2797                             let seen = self.freevars_seen
2798                                            .entry(function_id)
2799                                            .or_insert_with(|| NodeMap());
2800                             if let Some(&index) = seen.get(&node_id) {
2801                                 def = Def::Upvar(node_def_id, node_id, index, function_id);
2802                                 continue;
2803                             }
2804                             let vec = self.freevars
2805                                           .entry(function_id)
2806                                           .or_insert_with(|| vec![]);
2807                             let depth = vec.len();
2808                             vec.push(Freevar {
2809                                 def: prev_def,
2810                                 span: span,
2811                             });
2812
2813                             def = Def::Upvar(node_def_id, node_id, depth, function_id);
2814                             seen.insert(node_id, depth);
2815                         }
2816                         ItemRibKind | MethodRibKind => {
2817                             // This was an attempt to access an upvar inside a
2818                             // named function item. This is not allowed, so we
2819                             // report an error.
2820                             resolve_error(self,
2821                                           span,
2822                                           ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2823                             return None;
2824                         }
2825                         ConstantItemRibKind => {
2826                             // Still doesn't deal with upvars
2827                             resolve_error(self,
2828                                           span,
2829                                           ResolutionError::AttemptToUseNonConstantValueInConstant);
2830                             return None;
2831                         }
2832                     }
2833                 }
2834             }
2835             Def::TyParam(..) | Def::SelfTy(..) => {
2836                 for rib in ribs {
2837                     match rib.kind {
2838                         NormalRibKind | MethodRibKind | ClosureRibKind(..) |
2839                         AnonymousModuleRibKind(..) => {
2840                             // Nothing to do. Continue.
2841                         }
2842                         ItemRibKind => {
2843                             // This was an attempt to use a type parameter outside
2844                             // its scope.
2845
2846                             resolve_error(self,
2847                                           span,
2848                                           ResolutionError::TypeParametersFromOuterFunction);
2849                             return None;
2850                         }
2851                         ConstantItemRibKind => {
2852                             // see #9186
2853                             resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
2854                             return None;
2855                         }
2856                     }
2857                 }
2858             }
2859             _ => {}
2860         }
2861         return Some(def);
2862     }
2863
2864     // resolve a "module-relative" path, e.g. a::b::c
2865     fn resolve_module_relative_path(&mut self,
2866                                     span: Span,
2867                                     segments: &[hir::PathSegment],
2868                                     namespace: Namespace)
2869                                     -> Option<(Def, LastPrivate)> {
2870         let module_path = segments.split_last()
2871                                   .unwrap()
2872                                   .1
2873                                   .iter()
2874                                   .map(|ps| ps.identifier.name)
2875                                   .collect::<Vec<_>>();
2876
2877         let containing_module;
2878         let last_private;
2879         let current_module = self.current_module;
2880         match self.resolve_module_path(current_module, &module_path, UseLexicalScope, span) {
2881             Failed(err) => {
2882                 let (span, msg) = match err {
2883                     Some((span, msg)) => (span, msg),
2884                     None => {
2885                         let msg = format!("Use of undeclared type or module `{}`",
2886                                           names_to_string(&module_path));
2887                         (span, msg)
2888                     }
2889                 };
2890
2891                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2892                 return None;
2893             }
2894             Indeterminate => return None,
2895             Success((resulting_module, resulting_last_private)) => {
2896                 containing_module = resulting_module;
2897                 last_private = resulting_last_private;
2898             }
2899         }
2900
2901         let name = segments.last().unwrap().identifier.name;
2902         let result = self.resolve_name_in_module(containing_module, name, namespace, false, true);
2903         let def = match result {
2904             Success(binding) => {
2905                 let (def, lp) = binding.def_and_lp();
2906                 (def, last_private.or(lp))
2907             }
2908             _ => return None,
2909         };
2910         return Some(def);
2911     }
2912
2913     /// Invariant: This must be called only during main resolution, not during
2914     /// import resolution.
2915     fn resolve_crate_relative_path(&mut self,
2916                                    span: Span,
2917                                    segments: &[hir::PathSegment],
2918                                    namespace: Namespace)
2919                                    -> Option<(Def, LastPrivate)> {
2920         let module_path = segments.split_last()
2921                                   .unwrap()
2922                                   .1
2923                                   .iter()
2924                                   .map(|ps| ps.identifier.name)
2925                                   .collect::<Vec<_>>();
2926
2927         let root_module = self.graph_root;
2928
2929         let containing_module;
2930         let last_private;
2931         match self.resolve_module_path_from_root(root_module,
2932                                                  &module_path,
2933                                                  0,
2934                                                  span,
2935                                                  LastMod(AllPublic)) {
2936             Failed(err) => {
2937                 let (span, msg) = match err {
2938                     Some((span, msg)) => (span, msg),
2939                     None => {
2940                         let msg = format!("Use of undeclared module `::{}`",
2941                                           names_to_string(&module_path));
2942                         (span, msg)
2943                     }
2944                 };
2945
2946                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2947                 return None;
2948             }
2949
2950             Indeterminate => return None,
2951
2952             Success((resulting_module, resulting_last_private)) => {
2953                 containing_module = resulting_module;
2954                 last_private = resulting_last_private;
2955             }
2956         }
2957
2958         let name = segments.last().unwrap().identifier.name;
2959         match self.resolve_name_in_module(containing_module, name, namespace, false, true) {
2960             Success(binding) => {
2961                 let (def, lp) = binding.def_and_lp();
2962                 Some((def, last_private.or(lp)))
2963             }
2964             _ => None,
2965         }
2966     }
2967
2968     fn resolve_identifier_in_local_ribs(&mut self,
2969                                         ident: hir::Ident,
2970                                         namespace: Namespace)
2971                                         -> Option<LocalDef> {
2972         // Check the local set of ribs.
2973         let name = match namespace { ValueNS => ident.name, TypeNS => ident.unhygienic_name };
2974
2975         for i in (0 .. self.get_ribs(namespace).len()).rev() {
2976             if let Some(def_like) = self.get_ribs(namespace)[i].bindings.get(&name).cloned() {
2977                 match def_like {
2978                     DlDef(def) => {
2979                         debug!("(resolving path in local ribs) resolved `{}` to {:?} at {}",
2980                                name,
2981                                def,
2982                                i);
2983                         return Some(LocalDef {
2984                             ribs: Some((namespace, i)),
2985                             def: def,
2986                         });
2987                     }
2988                     def_like => {
2989                         debug!("(resolving path in local ribs) resolved `{}` to pseudo-def {:?}",
2990                                name,
2991                                def_like);
2992                         return None;
2993                     }
2994                 }
2995             }
2996
2997             if let AnonymousModuleRibKind(module) = self.get_ribs(namespace)[i].kind {
2998                 if let Success(binding) = self.resolve_name_in_module(module,
2999                                                                       ident.unhygienic_name,
3000                                                                       namespace,
3001                                                                       true,
3002                                                                       true) {
3003                     if let Some(def) = binding.def() {
3004                         return Some(LocalDef::from_def(def));
3005                     }
3006                 }
3007             }
3008         }
3009
3010         None
3011     }
3012
3013     fn with_no_errors<T, F>(&mut self, f: F) -> T
3014         where F: FnOnce(&mut Resolver) -> T
3015     {
3016         self.emit_errors = false;
3017         let rs = f(self);
3018         self.emit_errors = true;
3019         rs
3020     }
3021
3022     fn find_fallback_in_self_type(&mut self, name: Name) -> FallbackSuggestion {
3023         fn extract_path_and_node_id(t: &Ty,
3024                                     allow: FallbackChecks)
3025                                     -> Option<(Path, NodeId, FallbackChecks)> {
3026             match t.node {
3027                 TyPath(None, ref path) => Some((path.clone(), t.id, allow)),
3028                 TyPtr(ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, OnlyTraitAndStatics),
3029                 TyRptr(_, ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, allow),
3030                 // This doesn't handle the remaining `Ty` variants as they are not
3031                 // that commonly the self_type, it might be interesting to provide
3032                 // support for those in future.
3033                 _ => None,
3034             }
3035         }
3036
3037         fn get_module<'a, 'tcx>(this: &mut Resolver<'a, 'tcx>,
3038                                 span: Span,
3039                                 name_path: &[ast::Name])
3040                                 -> Option<Module<'a>> {
3041             let root = this.current_module;
3042             let last_name = name_path.last().unwrap();
3043
3044             if name_path.len() == 1 {
3045                 match this.primitive_type_table.primitive_types.get(last_name) {
3046                     Some(_) => None,
3047                     None => this.current_module.resolve_name(*last_name, TypeNS, true).success()
3048                                                .and_then(NameBinding::module)
3049                 }
3050             } else {
3051                 match this.resolve_module_path(root, &name_path, UseLexicalScope, span) {
3052                     Success((module, _)) => Some(module),
3053                     _ => None,
3054                 }
3055             }
3056         }
3057
3058         fn is_static_method(this: &Resolver, did: DefId) -> bool {
3059             if let Some(node_id) = this.ast_map.as_local_node_id(did) {
3060                 let sig = match this.ast_map.get(node_id) {
3061                     hir_map::NodeTraitItem(trait_item) => match trait_item.node {
3062                         hir::MethodTraitItem(ref sig, _) => sig,
3063                         _ => return false,
3064                     },
3065                     hir_map::NodeImplItem(impl_item) => match impl_item.node {
3066                         hir::ImplItemKind::Method(ref sig, _) => sig,
3067                         _ => return false,
3068                     },
3069                     _ => return false,
3070                 };
3071                 sig.explicit_self.node == hir::SelfStatic
3072             } else {
3073                 this.session.cstore.is_static_method(did)
3074             }
3075         }
3076
3077         let (path, node_id, allowed) = match self.current_self_type {
3078             Some(ref ty) => match extract_path_and_node_id(ty, Everything) {
3079                 Some(x) => x,
3080                 None => return NoSuggestion,
3081             },
3082             None => return NoSuggestion,
3083         };
3084
3085         if allowed == Everything {
3086             // Look for a field with the same name in the current self_type.
3087             match self.def_map.borrow().get(&node_id).map(|d| d.full_def()) {
3088                 Some(Def::Enum(did)) |
3089                 Some(Def::TyAlias(did)) |
3090                 Some(Def::Struct(did)) |
3091                 Some(Def::Variant(_, did)) => match self.structs.get(&did) {
3092                     None => {}
3093                     Some(fields) => {
3094                         if fields.iter().any(|&field_name| name == field_name) {
3095                             return Field;
3096                         }
3097                     }
3098                 },
3099                 _ => {} // Self type didn't resolve properly
3100             }
3101         }
3102
3103         let name_path = path.segments.iter().map(|seg| seg.identifier.name).collect::<Vec<_>>();
3104
3105         // Look for a method in the current self type's impl module.
3106         if let Some(module) = get_module(self, path.span, &name_path) {
3107             if let Success(binding) = module.resolve_name(name, ValueNS, true) {
3108                 if let Some(Def::Method(did)) = binding.def() {
3109                     if is_static_method(self, did) {
3110                         return StaticMethod(path_names_to_string(&path, 0));
3111                     }
3112                     if self.current_trait_ref.is_some() {
3113                         return TraitItem;
3114                     } else if allowed == Everything {
3115                         return Method;
3116                     }
3117                 }
3118             }
3119         }
3120
3121         // Look for a method in the current trait.
3122         if let Some((trait_did, ref trait_ref)) = self.current_trait_ref {
3123             if let Some(&did) = self.trait_item_map.get(&(name, trait_did)) {
3124                 if is_static_method(self, did) {
3125                     return TraitMethod(path_names_to_string(&trait_ref.path, 0));
3126                 } else {
3127                     return TraitItem;
3128                 }
3129             }
3130         }
3131
3132         NoSuggestion
3133     }
3134
3135     fn find_best_match(&mut self, name: &str) -> SuggestionType {
3136         if let Some(macro_name) = self.session.available_macros
3137                                   .borrow().iter().find(|n| n.as_str() == name) {
3138             return SuggestionType::Macro(format!("{}!", macro_name));
3139         }
3140
3141         let names = self.value_ribs
3142                     .iter()
3143                     .rev()
3144                     .flat_map(|rib| rib.bindings.keys());
3145
3146         if let Some(found) = find_best_match_for_name(names, name, None) {
3147             if name != found {
3148                 return SuggestionType::Function(found);
3149             }
3150         } SuggestionType::NotFound
3151     }
3152
3153     fn resolve_expr(&mut self, expr: &Expr) {
3154         // First, record candidate traits for this expression if it could
3155         // result in the invocation of a method call.
3156
3157         self.record_candidate_traits_for_expr_if_necessary(expr);
3158
3159         // Next, resolve the node.
3160         match expr.node {
3161             ExprPath(ref maybe_qself, ref path) => {
3162                 let resolution = match self.resolve_possibly_assoc_item(expr.id,
3163                                                                         maybe_qself.as_ref(),
3164                                                                         path,
3165                                                                         ValueNS,
3166                                                                         true) {
3167                     // `<T>::a::b::c` is resolved by typeck alone.
3168                     TypecheckRequired => {
3169                         let method_name = path.segments.last().unwrap().identifier.name;
3170                         let traits = self.get_traits_containing_item(method_name);
3171                         self.trait_map.insert(expr.id, traits);
3172                         intravisit::walk_expr(self, expr);
3173                         return;
3174                     }
3175                     ResolveAttempt(resolution) => resolution,
3176                 };
3177
3178                 // This is a local path in the value namespace. Walk through
3179                 // scopes looking for it.
3180                 if let Some(path_res) = resolution {
3181                     // Check if struct variant
3182                     let is_struct_variant = if let Def::Variant(_, variant_id) = path_res.base_def {
3183                         self.structs.contains_key(&variant_id)
3184                     } else {
3185                         false
3186                     };
3187                     if is_struct_variant {
3188                         let _ = self.structs.contains_key(&path_res.base_def.def_id());
3189                         let path_name = path_names_to_string(path, 0);
3190
3191                         let mut err = resolve_struct_error(self,
3192                                         expr.span,
3193                                         ResolutionError::StructVariantUsedAsFunction(&path_name));
3194
3195                         let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3196                                           path_name);
3197                         if self.emit_errors {
3198                             err.fileline_help(expr.span, &msg);
3199                         } else {
3200                             err.span_help(expr.span, &msg);
3201                         }
3202                         err.emit();
3203                         self.record_def(expr.id, err_path_resolution());
3204                     } else {
3205                         // Write the result into the def map.
3206                         debug!("(resolving expr) resolved `{}`",
3207                                path_names_to_string(path, 0));
3208
3209                         // Partial resolutions will need the set of traits in scope,
3210                         // so they can be completed during typeck.
3211                         if path_res.depth != 0 {
3212                             let method_name = path.segments.last().unwrap().identifier.name;
3213                             let traits = self.get_traits_containing_item(method_name);
3214                             self.trait_map.insert(expr.id, traits);
3215                         }
3216
3217                         self.record_def(expr.id, path_res);
3218                     }
3219                 } else {
3220                     // Be helpful if the name refers to a struct
3221                     // (The pattern matching def_tys where the id is in self.structs
3222                     // matches on regular structs while excluding tuple- and enum-like
3223                     // structs, which wouldn't result in this error.)
3224                     let path_name = path_names_to_string(path, 0);
3225                     let type_res = self.with_no_errors(|this| {
3226                         this.resolve_path(expr.id, path, 0, TypeNS, false)
3227                     });
3228
3229                     self.record_def(expr.id, err_path_resolution());
3230                     match type_res.map(|r| r.base_def) {
3231                         Some(Def::Struct(..)) => {
3232                             let mut err = resolve_struct_error(self,
3233                                 expr.span,
3234                                 ResolutionError::StructVariantUsedAsFunction(&path_name));
3235
3236                             let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3237                                               path_name);
3238                             if self.emit_errors {
3239                                 err.fileline_help(expr.span, &msg);
3240                             } else {
3241                                 err.span_help(expr.span, &msg);
3242                             }
3243                             err.emit();
3244                         }
3245                         _ => {
3246                             // Keep reporting some errors even if they're ignored above.
3247                             self.resolve_path(expr.id, path, 0, ValueNS, true);
3248
3249                             let mut method_scope = false;
3250                             self.value_ribs.iter().rev().all(|rib| {
3251                                 method_scope = match rib.kind {
3252                                     MethodRibKind => true,
3253                                     ItemRibKind | ConstantItemRibKind => false,
3254                                     _ => return true, // Keep advancing
3255                                 };
3256                                 false // Stop advancing
3257                             });
3258
3259                             if method_scope && special_names::self_.as_str() == &path_name[..] {
3260                                 resolve_error(self,
3261                                               expr.span,
3262                                               ResolutionError::SelfNotAvailableInStaticMethod);
3263                             } else {
3264                                 let last_name = path.segments.last().unwrap().identifier.name;
3265                                 let mut msg = match self.find_fallback_in_self_type(last_name) {
3266                                     NoSuggestion => {
3267                                         // limit search to 5 to reduce the number
3268                                         // of stupid suggestions
3269                                         match self.find_best_match(&path_name) {
3270                                             SuggestionType::Macro(s) => {
3271                                                 format!("the macro `{}`", s)
3272                                             }
3273                                             SuggestionType::Function(s) => format!("`{}`", s),
3274                                             SuggestionType::NotFound => "".to_string(),
3275                                         }
3276                                     }
3277                                     Field => format!("`self.{}`", path_name),
3278                                     Method |
3279                                     TraitItem => format!("to call `self.{}`", path_name),
3280                                     TraitMethod(path_str) |
3281                                     StaticMethod(path_str) =>
3282                                         format!("to call `{}::{}`", path_str, path_name),
3283                                 };
3284
3285                                 let mut context =  UnresolvedNameContext::Other;
3286                                 if !msg.is_empty() {
3287                                     msg = format!(". Did you mean {}?", msg);
3288                                 } else {
3289                                     // we check if this a module and if so, we display a help
3290                                     // message
3291                                     let name_path = path.segments.iter()
3292                                                         .map(|seg| seg.identifier.name)
3293                                                         .collect::<Vec<_>>();
3294                                     let current_module = self.current_module;
3295
3296                                     match self.resolve_module_path(current_module,
3297                                                                    &name_path[..],
3298                                                                    UseLexicalScope,
3299                                                                    expr.span) {
3300                                         Success(_) => {
3301                                             context = UnresolvedNameContext::PathIsMod(expr.id);
3302                                         },
3303                                         _ => {},
3304                                     };
3305                                 }
3306
3307                                 resolve_error(self,
3308                                               expr.span,
3309                                               ResolutionError::UnresolvedName(
3310                                                   &path_name, &msg, context));
3311                             }
3312                         }
3313                     }
3314                 }
3315
3316                 intravisit::walk_expr(self, expr);
3317             }
3318
3319             ExprStruct(ref path, _, _) => {
3320                 // Resolve the path to the structure it goes to. We don't
3321                 // check to ensure that the path is actually a structure; that
3322                 // is checked later during typeck.
3323                 match self.resolve_path(expr.id, path, 0, TypeNS, false) {
3324                     Some(definition) => self.record_def(expr.id, definition),
3325                     None => {
3326                         debug!("(resolving expression) didn't find struct def",);
3327
3328                         resolve_error(self,
3329                                       path.span,
3330                                       ResolutionError::DoesNotNameAStruct(
3331                                                                 &path_names_to_string(path, 0))
3332                                      );
3333                         self.record_def(expr.id, err_path_resolution());
3334                     }
3335                 }
3336
3337                 intravisit::walk_expr(self, expr);
3338             }
3339
3340             ExprLoop(_, Some(label)) | ExprWhile(_, _, Some(label)) => {
3341                 self.with_label_rib(|this| {
3342                     let def_like = DlDef(Def::Label(expr.id));
3343
3344                     {
3345                         let rib = this.label_ribs.last_mut().unwrap();
3346                         rib.bindings.insert(label.name, def_like);
3347                     }
3348
3349                     intravisit::walk_expr(this, expr);
3350                 })
3351             }
3352
3353             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
3354                 match self.search_label(label.node.name) {
3355                     None => {
3356                         self.record_def(expr.id, err_path_resolution());
3357                         resolve_error(self,
3358                                       label.span,
3359                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
3360                     }
3361                     Some(DlDef(def @ Def::Label(_))) => {
3362                         // Since this def is a label, it is never read.
3363                         self.record_def(expr.id,
3364                                         PathResolution {
3365                                             base_def: def,
3366                                             last_private: LastMod(AllPublic),
3367                                             depth: 0,
3368                                         })
3369                     }
3370                     Some(_) => {
3371                         self.session.span_bug(expr.span, "label wasn't mapped to a label def!")
3372                     }
3373                 }
3374             }
3375
3376             _ => {
3377                 intravisit::walk_expr(self, expr);
3378             }
3379         }
3380     }
3381
3382     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3383         match expr.node {
3384             ExprField(_, name) => {
3385                 // FIXME(#6890): Even though you can't treat a method like a
3386                 // field, we need to add any trait methods we find that match
3387                 // the field name so that we can do some nice error reporting
3388                 // later on in typeck.
3389                 let traits = self.get_traits_containing_item(name.node);
3390                 self.trait_map.insert(expr.id, traits);
3391             }
3392             ExprMethodCall(name, _, _) => {
3393                 debug!("(recording candidate traits for expr) recording traits for {}",
3394                        expr.id);
3395                 let traits = self.get_traits_containing_item(name.node);
3396                 self.trait_map.insert(expr.id, traits);
3397             }
3398             _ => {
3399                 // Nothing to do.
3400             }
3401         }
3402     }
3403
3404     fn get_traits_containing_item(&mut self, name: Name) -> Vec<DefId> {
3405         debug!("(getting traits containing item) looking for '{}'", name);
3406
3407         fn add_trait_info(found_traits: &mut Vec<DefId>, trait_def_id: DefId, name: Name) {
3408             debug!("(adding trait info) found trait {:?} for method '{}'",
3409                    trait_def_id,
3410                    name);
3411             found_traits.push(trait_def_id);
3412         }
3413
3414         let mut found_traits = Vec::new();
3415         let mut search_module = self.current_module;
3416         loop {
3417             // Look for the current trait.
3418             match self.current_trait_ref {
3419                 Some((trait_def_id, _)) => {
3420                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3421                         add_trait_info(&mut found_traits, trait_def_id, name);
3422                     }
3423                 }
3424                 None => {} // Nothing to do.
3425             }
3426
3427             // Look for trait children.
3428             build_reduced_graph::populate_module_if_necessary(self, &search_module);
3429
3430             search_module.for_each_child(|_, ns, name_binding| {
3431                 if ns != TypeNS { return }
3432                 let trait_def_id = match name_binding.def() {
3433                     Some(Def::Trait(trait_def_id)) => trait_def_id,
3434                     Some(..) | None => return,
3435                 };
3436                 if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3437                     add_trait_info(&mut found_traits, trait_def_id, name);
3438                     let trait_name = self.get_trait_name(trait_def_id);
3439                     self.record_use(trait_name, TypeNS, name_binding);
3440                 }
3441             });
3442
3443             // Look for shadowed traits.
3444             for binding in search_module.shadowed_traits.borrow().iter() {
3445                 let did = binding.def().unwrap().def_id();
3446                 if self.trait_item_map.contains_key(&(name, did)) {
3447                     add_trait_info(&mut found_traits, did, name);
3448                     let trait_name = self.get_trait_name(did);
3449                     self.record_use(trait_name, TypeNS, binding);
3450                 }
3451             }
3452
3453             match search_module.parent_link {
3454                 NoParentLink | ModuleParentLink(..) => break,
3455                 BlockParentLink(parent_module, _) => {
3456                     search_module = parent_module;
3457                 }
3458             }
3459         }
3460
3461         found_traits
3462     }
3463
3464     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3465         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3466         assert!(match resolution.last_private {
3467                     LastImport{..} => false,
3468                     _ => true,
3469                 },
3470                 "Import should only be used for `use` directives");
3471
3472         if let Some(prev_res) = self.def_map.borrow_mut().insert(node_id, resolution) {
3473             let span = self.ast_map.opt_span(node_id).unwrap_or(codemap::DUMMY_SP);
3474             self.session.span_bug(span,
3475                                   &format!("path resolved multiple times ({:?} before, {:?} now)",
3476                                            prev_res,
3477                                            resolution));
3478         }
3479     }
3480
3481     fn enforce_default_binding_mode(&mut self,
3482                                     pat: &Pat,
3483                                     pat_binding_mode: BindingMode,
3484                                     descr: &str) {
3485         match pat_binding_mode {
3486             BindByValue(_) => {}
3487             BindByRef(..) => {
3488                 resolve_error(self,
3489                               pat.span,
3490                               ResolutionError::CannotUseRefBindingModeWith(descr));
3491             }
3492         }
3493     }
3494 }
3495
3496
3497 fn names_to_string(names: &[Name]) -> String {
3498     let mut first = true;
3499     let mut result = String::new();
3500     for name in names {
3501         if first {
3502             first = false
3503         } else {
3504             result.push_str("::")
3505         }
3506         result.push_str(&name.as_str());
3507     }
3508     result
3509 }
3510
3511 fn path_names_to_string(path: &Path, depth: usize) -> String {
3512     let names: Vec<ast::Name> = path.segments[..path.segments.len() - depth]
3513                                     .iter()
3514                                     .map(|seg| seg.identifier.name)
3515                                     .collect();
3516     names_to_string(&names[..])
3517 }
3518
3519 /// A somewhat inefficient routine to obtain the name of a module.
3520 fn module_to_string<'a>(module: Module<'a>) -> String {
3521     let mut names = Vec::new();
3522
3523     fn collect_mod<'a>(names: &mut Vec<ast::Name>, module: Module<'a>) {
3524         match module.parent_link {
3525             NoParentLink => {}
3526             ModuleParentLink(ref module, name) => {
3527                 names.push(name);
3528                 collect_mod(names, module);
3529             }
3530             BlockParentLink(ref module, _) => {
3531                 // danger, shouldn't be ident?
3532                 names.push(special_idents::opaque.name);
3533                 collect_mod(names, module);
3534             }
3535         }
3536     }
3537     collect_mod(&mut names, module);
3538
3539     if names.is_empty() {
3540         return "???".to_string();
3541     }
3542     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
3543 }
3544
3545 fn err_path_resolution() -> PathResolution {
3546     PathResolution {
3547         base_def: Def::Err,
3548         last_private: LastMod(AllPublic),
3549         depth: 0,
3550     }
3551 }
3552
3553
3554 pub struct CrateMap {
3555     pub def_map: RefCell<DefMap>,
3556     pub freevars: FreevarMap,
3557     pub export_map: ExportMap,
3558     pub trait_map: TraitMap,
3559     pub external_exports: ExternalExports,
3560     pub glob_map: Option<GlobMap>,
3561 }
3562
3563 #[derive(PartialEq,Copy, Clone)]
3564 pub enum MakeGlobMap {
3565     Yes,
3566     No,
3567 }
3568
3569 /// Entry point to crate resolution.
3570 pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
3571                                ast_map: &'a hir_map::Map<'tcx>,
3572                                make_glob_map: MakeGlobMap)
3573                                -> CrateMap {
3574     // Currently, we ignore the name resolution data structures for
3575     // the purposes of dependency tracking. Instead we will run name
3576     // resolution and include its output in the hash of each item,
3577     // much like we do for macro expansion. In other words, the hash
3578     // reflects not just its contents but the results of name
3579     // resolution on those contents. Hopefully we'll push this back at
3580     // some point.
3581     let _task = ast_map.dep_graph.in_task(DepNode::Resolve);
3582
3583     let krate = ast_map.krate();
3584     let arenas = Resolver::arenas();
3585     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, &arenas, None);
3586
3587     resolver.resolve_crate(krate);
3588
3589     check_unused::check_crate(&mut resolver, krate);
3590
3591     CrateMap {
3592         def_map: resolver.def_map,
3593         freevars: resolver.freevars,
3594         export_map: resolver.export_map,
3595         trait_map: resolver.trait_map,
3596         external_exports: resolver.external_exports,
3597         glob_map: if resolver.make_glob_map {
3598             Some(resolver.glob_map)
3599         } else {
3600             None
3601         },
3602     }
3603 }
3604
3605 /// Builds a name resolution walker to be used within this module,
3606 /// or used externally, with an optional callback function.
3607 ///
3608 /// The callback takes a &mut bool which allows callbacks to end a
3609 /// walk when set to true, passing through the rest of the walk, while
3610 /// preserving the ribs + current module. This allows resolve_path
3611 /// calls to be made with the correct scope info. The node in the
3612 /// callback corresponds to the current node in the walk.
3613 pub fn create_resolver<'a, 'tcx>(session: &'a Session,
3614                                  ast_map: &'a hir_map::Map<'tcx>,
3615                                  krate: &'a Crate,
3616                                  make_glob_map: MakeGlobMap,
3617                                  arenas: &'a ResolverArenas<'a>,
3618                                  callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>)
3619                                  -> Resolver<'a, 'tcx> {
3620     let mut resolver = Resolver::new(session, ast_map, make_glob_map, arenas);
3621
3622     resolver.callback = callback;
3623
3624     build_reduced_graph::build_reduced_graph(&mut resolver, krate);
3625
3626     resolve_imports::resolve_imports(&mut resolver);
3627
3628     resolver
3629 }
3630
3631 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }