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, PatKind, Path, PrimTy};
  84 use rustc_front::hir::{TraitRef, Ty, TyBool, TyChar, TyFloat, TyInt};
  85 use rustc_front::hir::{TyRptr, TyStr, TyUint, TyPath, TyPtr};
  86 use rustc_front::util::walk_pat;
  87
  88 use std::collections::{HashMap, HashSet};
  89 use std::cell::{Cell, RefCell};
  90 use std::fmt;
  91 use std::mem::replace;
  92
  93 use resolve_imports::{ImportDirective, NameResolution};
  94
  95 // NB: This module needs to be declared first so diagnostics are
  96 // registered before they are used.
  97 pub mod diagnostics;
  98
  99 mod check_unused;
 100 mod build_reduced_graph;
 101 mod resolve_imports;
 102
 103 // Perform the callback, not walking deeper if the return is true
 104 macro_rules! execute_callback {
 105     ($node: expr, $walker: expr) => (
 106         if let Some(ref callback) = $walker.callback {
 107             if callback($node, &mut $walker.resolved) {
 108                 return;
 109             }
 110         }
 111     )
 112 }
 113
 114 enum SuggestionType {
 115     Macro(String),
 116     Function(token::InternedString),
 117     NotFound,
 118 }
 119
 120 pub enum ResolutionError<'a> {
 121     /// error E0401: can't use type parameters from outer function
 122     TypeParametersFromOuterFunction,
 123     /// error E0402: cannot use an outer type parameter in this context
 124     OuterTypeParameterContext,
 125     /// error E0403: the name is already used for a type parameter in this type parameter list
 126     NameAlreadyUsedInTypeParameterList(Name),
 127     /// error E0404: is not a trait
 128     IsNotATrait(&'a str),
 129     /// error E0405: use of undeclared trait name
 130     UndeclaredTraitName(&'a str),
 131     /// error E0406: undeclared associated type
 132     UndeclaredAssociatedType,
 133     /// error E0407: method is not a member of trait
 134     MethodNotMemberOfTrait(Name, &'a str),
 135     /// error E0437: type is not a member of trait
 136     TypeNotMemberOfTrait(Name, &'a str),
 137     /// error E0438: const is not a member of trait
 138     ConstNotMemberOfTrait(Name, &'a str),
 139     /// error E0408: variable `{}` from pattern #1 is not bound in pattern
 140     VariableNotBoundInPattern(Name, usize),
 141     /// error E0409: variable is bound with different mode in pattern #{} than in pattern #1
 142     VariableBoundWithDifferentMode(Name, usize),
 143     /// error E0410: variable from pattern is not bound in pattern #1
 144     VariableNotBoundInParentPattern(Name, usize),
 145     /// error E0411: use of `Self` outside of an impl or trait
 146     SelfUsedOutsideImplOrTrait,
 147     /// error E0412: use of undeclared
 148     UseOfUndeclared(&'a str, &'a str),
 149     /// error E0413: declaration shadows an enum variant or unit-like struct in scope
 150     DeclarationShadowsEnumVariantOrUnitLikeStruct(Name),
 151     /// error E0414: only irrefutable patterns allowed here
 152     OnlyIrrefutablePatternsAllowedHere(DefId, Name),
 153     /// error E0415: identifier is bound more than once in this parameter list
 154     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 155     /// error E0416: identifier is bound more than once in the same pattern
 156     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 157     /// error E0417: static variables cannot be referenced in a pattern
 158     StaticVariableReference,
 159     /// error E0418: is not an enum variant, struct or const
 160     NotAnEnumVariantStructOrConst(&'a str),
 161     /// error E0419: unresolved enum variant, struct or const
 162     UnresolvedEnumVariantStructOrConst(&'a str),
 163     /// error E0420: is not an associated const
 164     NotAnAssociatedConst(&'a str),
 165     /// error E0421: unresolved associated const
 166     UnresolvedAssociatedConst(&'a str),
 167     /// error E0422: does not name a struct
 168     DoesNotNameAStruct(&'a str),
 169     /// error E0423: is a struct variant name, but this expression uses it like a function name
 170     StructVariantUsedAsFunction(&'a str),
 171     /// error E0424: `self` is not available in a static method
 172     SelfNotAvailableInStaticMethod,
 173     /// error E0425: unresolved name
 174     UnresolvedName(&'a str, &'a str, UnresolvedNameContext),
 175     /// error E0426: use of undeclared label
 176     UndeclaredLabel(&'a str),
 177     /// error E0427: cannot use `ref` binding mode with ...
 178     CannotUseRefBindingModeWith(&'a str),
 179     /// error E0428: duplicate definition
 180     DuplicateDefinition(&'a str, Name),
 181     /// error E0429: `self` imports are only allowed within a { } list
 182     SelfImportsOnlyAllowedWithin,
 183     /// error E0430: `self` import can only appear once in the list
 184     SelfImportCanOnlyAppearOnceInTheList,
 185     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 186     SelfImportOnlyInImportListWithNonEmptyPrefix,
 187     /// error E0432: unresolved import
 188     UnresolvedImport(Option<(&'a str, &'a str)>),
 189     /// error E0433: failed to resolve
 190     FailedToResolve(&'a str),
 191     /// error E0434: can't capture dynamic environment in a fn item
 192     CannotCaptureDynamicEnvironmentInFnItem,
 193     /// error E0435: attempt to use a non-constant value in a constant
 194     AttemptToUseNonConstantValueInConstant,
 195 }
 196
 197 /// Context of where `ResolutionError::UnresolvedName` arose.
 198 #[derive(Clone, PartialEq, Eq, Debug)]
 199 pub enum UnresolvedNameContext {
 200     /// `PathIsMod(id)` indicates that a given path, used in
 201     /// expression context, actually resolved to a module rather than
 202     /// a value. The `id` attached to the variant is the node id of
 203     /// the erroneous path expression.
 204     PathIsMod(ast::NodeId),
 205
 206     /// `Other` means we have no extra information about the context
 207     /// of the unresolved name error. (Maybe we could eliminate all
 208     /// such cases; but for now, this is an information-free default.)
 209     Other,
 210 }
 211
 212 fn resolve_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 213                                        span: syntax::codemap::Span,
 214                                        resolution_error: ResolutionError<'b>) {
 215     resolve_struct_error(resolver, span, resolution_error).emit();
 216 }
 217
 218 fn resolve_struct_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 219                                               span: syntax::codemap::Span,
 220                                               resolution_error: ResolutionError<'b>)
 221                                               -> DiagnosticBuilder<'a> {
 222     if !resolver.emit_errors {
 223         return resolver.session.diagnostic().struct_dummy();
 224     }
 225
 226     match resolution_error {
 227         ResolutionError::TypeParametersFromOuterFunction => {
 228             struct_span_err!(resolver.session,
 229                              span,
 230                              E0401,
 231                              "can't use type parameters from outer function; try using a local \
 232                               type parameter instead")
 233         }
 234         ResolutionError::OuterTypeParameterContext => {
 235             struct_span_err!(resolver.session,
 236                              span,
 237                              E0402,
 238                              "cannot use an outer type parameter in this context")
 239         }
 240         ResolutionError::NameAlreadyUsedInTypeParameterList(name) => {
 241             struct_span_err!(resolver.session,
 242                              span,
 243                              E0403,
 244                              "the name `{}` is already used for a type parameter in this type \
 245                               parameter list",
 246                              name)
 247         }
 248         ResolutionError::IsNotATrait(name) => {
 249             struct_span_err!(resolver.session, span, E0404, "`{}` is not a trait", name)
 250         }
 251         ResolutionError::UndeclaredTraitName(name) => {
 252             struct_span_err!(resolver.session,
 253                              span,
 254                              E0405,
 255                              "use of undeclared trait name `{}`",
 256                              name)
 257         }
 258         ResolutionError::UndeclaredAssociatedType => {
 259             struct_span_err!(resolver.session, span, E0406, "undeclared associated type")
 260         }
 261         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 262             struct_span_err!(resolver.session,
 263                              span,
 264                              E0407,
 265                              "method `{}` is not a member of trait `{}`",
 266                              method,
 267                              trait_)
 268         }
 269         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 270             struct_span_err!(resolver.session,
 271                              span,
 272                              E0437,
 273                              "type `{}` is not a member of trait `{}`",
 274                              type_,
 275                              trait_)
 276         }
 277         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 278             struct_span_err!(resolver.session,
 279                              span,
 280                              E0438,
 281                              "const `{}` is not a member of trait `{}`",
 282                              const_,
 283                              trait_)
 284         }
 285         ResolutionError::VariableNotBoundInPattern(variable_name, pattern_number) => {
 286             struct_span_err!(resolver.session,
 287                              span,
 288                              E0408,
 289                              "variable `{}` from pattern #1 is not bound in pattern #{}",
 290                              variable_name,
 291                              pattern_number)
 292         }
 293         ResolutionError::VariableBoundWithDifferentMode(variable_name, pattern_number) => {
 294             struct_span_err!(resolver.session,
 295                              span,
 296                              E0409,
 297                              "variable `{}` is bound with different mode in pattern #{} than in \
 298                               pattern #1",
 299                              variable_name,
 300                              pattern_number)
 301         }
 302         ResolutionError::VariableNotBoundInParentPattern(variable_name, pattern_number) => {
 303             struct_span_err!(resolver.session,
 304                              span,
 305                              E0410,
 306                              "variable `{}` from pattern #{} is not bound in pattern #1",
 307                              variable_name,
 308                              pattern_number)
 309         }
 310         ResolutionError::SelfUsedOutsideImplOrTrait => {
 311             struct_span_err!(resolver.session,
 312                              span,
 313                              E0411,
 314                              "use of `Self` outside of an impl or trait")
 315         }
 316         ResolutionError::UseOfUndeclared(kind, name) => {
 317             struct_span_err!(resolver.session,
 318                              span,
 319                              E0412,
 320                              "use of undeclared {} `{}`",
 321                              kind,
 322                              name)
 323         }
 324         ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(name) => {
 325             struct_span_err!(resolver.session,
 326                              span,
 327                              E0413,
 328                              "declaration of `{}` shadows an enum variant \
 329                               or unit-like struct in scope",
 330                              name)
 331         }
 332         ResolutionError::OnlyIrrefutablePatternsAllowedHere(did, name) => {
 333             let mut err = struct_span_err!(resolver.session,
 334                                            span,
 335                                            E0414,
 336                                            "only irrefutable patterns allowed here");
 337             err.span_note(span,
 338                           "there already is a constant in scope sharing the same \
 339                            name as this pattern");
 340             if let Some(sp) = resolver.ast_map.span_if_local(did) {
 341                 err.span_note(sp, "constant defined here");
 342             }
 343             if let Success(binding) = resolver.current_module.resolve_name(name, ValueNS, true) {
 344                 if binding.is_import() {
 345                     err.span_note(binding.span.unwrap(), "constant imported here");
 346                 }
 347             }
 348             err
 349         }
 350         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 351             struct_span_err!(resolver.session,
 352                              span,
 353                              E0415,
 354                              "identifier `{}` is bound more than once in this parameter list",
 355                              identifier)
 356         }
 357         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 358             struct_span_err!(resolver.session,
 359                              span,
 360                              E0416,
 361                              "identifier `{}` is bound more than once in the same pattern",
 362                              identifier)
 363         }
 364         ResolutionError::StaticVariableReference => {
 365             struct_span_err!(resolver.session,
 366                              span,
 367                              E0417,
 368                              "static variables cannot be referenced in a pattern, use a \
 369                               `const` instead")
 370         }
 371         ResolutionError::NotAnEnumVariantStructOrConst(name) => {
 372             struct_span_err!(resolver.session,
 373                              span,
 374                              E0418,
 375                              "`{}` is not an enum variant, struct or const",
 376                              name)
 377         }
 378         ResolutionError::UnresolvedEnumVariantStructOrConst(name) => {
 379             struct_span_err!(resolver.session,
 380                              span,
 381                              E0419,
 382                              "unresolved enum variant, struct or const `{}`",
 383                              name)
 384         }
 385         ResolutionError::NotAnAssociatedConst(name) => {
 386             struct_span_err!(resolver.session,
 387                              span,
 388                              E0420,
 389                              "`{}` is not an associated const",
 390                              name)
 391         }
 392         ResolutionError::UnresolvedAssociatedConst(name) => {
 393             struct_span_err!(resolver.session,
 394                              span,
 395                              E0421,
 396                              "unresolved associated const `{}`",
 397                              name)
 398         }
 399         ResolutionError::DoesNotNameAStruct(name) => {
 400             struct_span_err!(resolver.session,
 401                              span,
 402                              E0422,
 403                              "`{}` does not name a structure",
 404                              name)
 405         }
 406         ResolutionError::StructVariantUsedAsFunction(path_name) => {
 407             struct_span_err!(resolver.session,
 408                              span,
 409                              E0423,
 410                              "`{}` is the name of a struct or struct variant, but this expression \
 411                              uses it like a function name",
 412                              path_name)
 413         }
 414         ResolutionError::SelfNotAvailableInStaticMethod => {
 415             struct_span_err!(resolver.session,
 416                              span,
 417                              E0424,
 418                              "`self` is not available in a static method. Maybe a `self` \
 419                              argument is missing?")
 420         }
 421         ResolutionError::UnresolvedName(path, msg, context) => {
 422             let mut err = struct_span_err!(resolver.session,
 423                                            span,
 424                                            E0425,
 425                                            "unresolved name `{}`{}",
 426                                            path,
 427                                            msg);
 428
 429             match context {
 430                 UnresolvedNameContext::Other => { } // no help available
 431                 UnresolvedNameContext::PathIsMod(id) => {
 432                     let mut help_msg = String::new();
 433                     let parent_id = resolver.ast_map.get_parent_node(id);
 434                     if let Some(hir_map::Node::NodeExpr(e)) = resolver.ast_map.find(parent_id) {
 435                         match e.node {
 436                             ExprField(_, ident) => {
 437                                 help_msg = format!("To reference an item from the \
 438                                                     `{module}` module, use \
 439                                                     `{module}::{ident}`",
 440                                                    module = path,
 441                                                    ident = ident.node);
 442                             }
 443                             ExprMethodCall(ident, _, _) => {
 444                                 help_msg = format!("To call a function from the \
 445                                                     `{module}` module, use \
 446                                                     `{module}::{ident}(..)`",
 447                                                    module = path,
 448                                                    ident = ident.node);
 449                             }
 450                             ExprCall(_, _) => {
 451                                 help_msg = format!("No function corresponds to `{module}(..)`",
 452                                                    module = path);
 453                             }
 454                             _ => { } // no help available
 455                         }
 456                     } else {
 457                         help_msg = format!("Module `{module}` cannot be the value of an expression",
 458                                            module = path);
 459                     }
 460
 461                     if !help_msg.is_empty() {
 462                         err.fileline_help(span, &help_msg);
 463                     }
 464                 }
 465             }
 466             err
 467         }
 468         ResolutionError::UndeclaredLabel(name) => {
 469             struct_span_err!(resolver.session,
 470                              span,
 471                              E0426,
 472                              "use of undeclared label `{}`",
 473                              name)
 474         }
 475         ResolutionError::CannotUseRefBindingModeWith(descr) => {
 476             struct_span_err!(resolver.session,
 477                              span,
 478                              E0427,
 479                              "cannot use `ref` binding mode with {}",
 480                              descr)
 481         }
 482         ResolutionError::DuplicateDefinition(namespace, name) => {
 483             struct_span_err!(resolver.session,
 484                              span,
 485                              E0428,
 486                              "duplicate definition of {} `{}`",
 487                              namespace,
 488                              name)
 489         }
 490         ResolutionError::SelfImportsOnlyAllowedWithin => {
 491             struct_span_err!(resolver.session,
 492                              span,
 493                              E0429,
 494                              "{}",
 495                              "`self` imports are only allowed within a { } list")
 496         }
 497         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 498             struct_span_err!(resolver.session,
 499                              span,
 500                              E0430,
 501                              "`self` import can only appear once in the list")
 502         }
 503         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 504             struct_span_err!(resolver.session,
 505                              span,
 506                              E0431,
 507                              "`self` import can only appear in an import list with a \
 508                               non-empty prefix")
 509         }
 510         ResolutionError::UnresolvedImport(name) => {
 511             let msg = match name {
 512                 Some((n, p)) => format!("unresolved import `{}`{}", n, p),
 513                 None => "unresolved import".to_owned(),
 514             };
 515             struct_span_err!(resolver.session, span, E0432, "{}", msg)
 516         }
 517         ResolutionError::FailedToResolve(msg) => {
 518             struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg)
 519         }
 520         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 521             struct_span_err!(resolver.session,
 522                              span,
 523                              E0434,
 524                              "{}",
 525                              "can't capture dynamic environment in a fn item; use the || { ... } \
 526                               closure form instead")
 527         }
 528         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 529             struct_span_err!(resolver.session,
 530                              span,
 531                              E0435,
 532                              "attempt to use a non-constant value in a constant")
 533         }
 534     }
 535 }
 536
 537 #[derive(Copy, Clone)]
 538 struct BindingInfo {
 539     span: Span,
 540     binding_mode: BindingMode,
 541 }
 542
 543 // Map from the name in a pattern to its binding mode.
 544 type BindingMap = HashMap<Name, BindingInfo>;
 545
 546 #[derive(Copy, Clone, PartialEq)]
 547 enum PatternBindingMode {
 548     RefutableMode,
 549     LocalIrrefutableMode,
 550     ArgumentIrrefutableMode,
 551 }
 552
 553 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 554 pub enum Namespace {
 555     TypeNS,
 556     ValueNS,
 557 }
 558
 559 impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
 560     fn visit_nested_item(&mut self, item: hir::ItemId) {
 561         self.visit_item(self.ast_map.expect_item(item.id))
 562     }
 563     fn visit_item(&mut self, item: &Item) {
 564         execute_callback!(hir_map::Node::NodeItem(item), self);
 565         self.resolve_item(item);
 566     }
 567     fn visit_arm(&mut self, arm: &Arm) {
 568         self.resolve_arm(arm);
 569     }
 570     fn visit_block(&mut self, block: &Block) {
 571         execute_callback!(hir_map::Node::NodeBlock(block), self);
 572         self.resolve_block(block);
 573     }
 574     fn visit_expr(&mut self, expr: &Expr) {
 575         execute_callback!(hir_map::Node::NodeExpr(expr), self);
 576         self.resolve_expr(expr);
 577     }
 578     fn visit_local(&mut self, local: &Local) {
 579         execute_callback!(hir_map::Node::NodeLocal(&local.pat), self);
 580         self.resolve_local(local);
 581     }
 582     fn visit_ty(&mut self, ty: &Ty) {
 583         self.resolve_type(ty);
 584     }
 585     fn visit_generics(&mut self, generics: &Generics) {
 586         self.resolve_generics(generics);
 587     }
 588     fn visit_poly_trait_ref(&mut self, tref: &hir::PolyTraitRef, m: &hir::TraitBoundModifier) {
 589         match self.resolve_trait_reference(tref.trait_ref.ref_id, &tref.trait_ref.path, 0) {
 590             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
 591             Err(_) => {
 592                 // error already reported
 593                 self.record_def(tref.trait_ref.ref_id, err_path_resolution())
 594             }
 595         }
 596         intravisit::walk_poly_trait_ref(self, tref, m);
 597     }
 598     fn visit_variant(&mut self,
 599                      variant: &hir::Variant,
 600                      generics: &Generics,
 601                      item_id: ast::NodeId) {
 602         execute_callback!(hir_map::Node::NodeVariant(variant), self);
 603         if let Some(ref dis_expr) = variant.node.disr_expr {
 604             // resolve the discriminator expr as a constant
 605             self.with_constant_rib(|this| {
 606                 this.visit_expr(dis_expr);
 607             });
 608         }
 609
 610         // `intravisit::walk_variant` without the discriminant expression.
 611         self.visit_variant_data(&variant.node.data,
 612                                 variant.node.name,
 613                                 generics,
 614                                 item_id,
 615                                 variant.span);
 616     }
 617     fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem) {
 618         execute_callback!(hir_map::Node::NodeForeignItem(foreign_item), self);
 619         let type_parameters = match foreign_item.node {
 620             ForeignItemFn(_, ref generics) => {
 621                 HasTypeParameters(generics, FnSpace, ItemRibKind)
 622             }
 623             ForeignItemStatic(..) => NoTypeParameters,
 624         };
 625         self.with_type_parameter_rib(type_parameters, |this| {
 626             intravisit::walk_foreign_item(this, foreign_item);
 627         });
 628     }
 629     fn visit_fn(&mut self,
 630                 function_kind: FnKind<'v>,
 631                 declaration: &'v FnDecl,
 632                 block: &'v Block,
 633                 _: Span,
 634                 node_id: NodeId) {
 635         let rib_kind = match function_kind {
 636             FnKind::ItemFn(_, generics, _, _, _, _) => {
 637                 self.visit_generics(generics);
 638                 ItemRibKind
 639             }
 640             FnKind::Method(_, sig, _) => {
 641                 self.visit_generics(&sig.generics);
 642                 self.visit_explicit_self(&sig.explicit_self);
 643                 MethodRibKind
 644             }
 645             FnKind::Closure => ClosureRibKind(node_id),
 646         };
 647         self.resolve_function(rib_kind, declaration, block);
 648     }
 649 }
 650
 651 pub type ErrorMessage = Option<(Span, String)>;
 652
 653 #[derive(Clone, PartialEq, Eq)]
 654 pub enum ResolveResult<T> {
 655     Failed(ErrorMessage), // Failed to resolve the name, optional helpful error message.
 656     Indeterminate, // Couldn't determine due to unresolved globs.
 657     Success(T), // Successfully resolved the import.
 658 }
 659
 660 impl<T> ResolveResult<T> {
 661     fn and_then<U, F: FnOnce(T) -> ResolveResult<U>>(self, f: F) -> ResolveResult<U> {
 662         match self {
 663             Failed(msg) => Failed(msg),
 664             Indeterminate => Indeterminate,
 665             Success(t) => f(t),
 666         }
 667     }
 668
 669     fn success(self) -> Option<T> {
 670         match self {
 671             Success(t) => Some(t),
 672             _ => None,
 673         }
 674     }
 675 }
 676
 677 enum FallbackSuggestion {
 678     NoSuggestion,
 679     Field,
 680     Method,
 681     TraitItem,
 682     StaticMethod(String),
 683     TraitMethod(String),
 684 }
 685
 686 #[derive(Copy, Clone)]
 687 enum TypeParameters<'tcx, 'a> {
 688     NoTypeParameters,
 689     HasTypeParameters(// Type parameters.
 690                       &'a Generics,
 691
 692                       // Identifies the things that these parameters
 693                       // were declared on (type, fn, etc)
 694                       ParamSpace,
 695
 696                       // The kind of the rib used for type parameters.
 697                       RibKind<'tcx>),
 698 }
 699
 700 // The rib kind controls the translation of local
 701 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 702 #[derive(Copy, Clone, Debug)]
 703 enum RibKind<'a> {
 704     // No translation needs to be applied.
 705     NormalRibKind,
 706
 707     // We passed through a closure scope at the given node ID.
 708     // Translate upvars as appropriate.
 709     ClosureRibKind(NodeId /* func id */),
 710
 711     // We passed through an impl or trait and are now in one of its
 712     // methods. Allow references to ty params that impl or trait
 713     // binds. Disallow any other upvars (including other ty params that are
 714     // upvars).
 715     MethodRibKind,
 716
 717     // We passed through an item scope. Disallow upvars.
 718     ItemRibKind,
 719
 720     // We're in a constant item. Can't refer to dynamic stuff.
 721     ConstantItemRibKind,
 722
 723     // We passed through an anonymous module.
 724     AnonymousModuleRibKind(Module<'a>),
 725 }
 726
 727 #[derive(Copy, Clone)]
 728 enum UseLexicalScopeFlag {
 729     DontUseLexicalScope,
 730     UseLexicalScope,
 731 }
 732
 733 enum ModulePrefixResult<'a> {
 734     NoPrefixFound,
 735     PrefixFound(Module<'a>, usize),
 736 }
 737
 738 #[derive(Copy, Clone)]
 739 enum AssocItemResolveResult {
 740     /// Syntax such as `<T>::item`, which can't be resolved until type
 741     /// checking.
 742     TypecheckRequired,
 743     /// We should have been able to resolve the associated item.
 744     ResolveAttempt(Option<PathResolution>),
 745 }
 746
 747 #[derive(Copy, Clone)]
 748 enum BareIdentifierPatternResolution {
 749     FoundStructOrEnumVariant(Def, LastPrivate),
 750     FoundConst(Def, LastPrivate, Name),
 751     BareIdentifierPatternUnresolved,
 752 }
 753
 754 /// One local scope.
 755 #[derive(Debug)]
 756 struct Rib<'a> {
 757     bindings: HashMap<Name, DefLike>,
 758     kind: RibKind<'a>,
 759 }
 760
 761 impl<'a> Rib<'a> {
 762     fn new(kind: RibKind<'a>) -> Rib<'a> {
 763         Rib {
 764             bindings: HashMap::new(),
 765             kind: kind,
 766         }
 767     }
 768 }
 769
 770 /// A definition along with the index of the rib it was found on
 771 struct LocalDef {
 772     ribs: Option<(Namespace, usize)>,
 773     def: Def,
 774 }
 775
 776 impl LocalDef {
 777     fn from_def(def: Def) -> Self {
 778         LocalDef {
 779             ribs: None,
 780             def: def,
 781         }
 782     }
 783 }
 784
 785 /// The link from a module up to its nearest parent node.
 786 #[derive(Clone,Debug)]
 787 enum ParentLink<'a> {
 788     NoParentLink,
 789     ModuleParentLink(Module<'a>, Name),
 790     BlockParentLink(Module<'a>, NodeId),
 791 }
 792
 793 /// One node in the tree of modules.
 794 pub struct ModuleS<'a> {
 795     parent_link: ParentLink<'a>,
 796     def: Option<Def>,
 797     is_public: bool,
 798     is_extern_crate: bool,
 799
 800     resolutions: RefCell<HashMap<(Name, Namespace), NameResolution<'a>>>,
 801     imports: RefCell<Vec<ImportDirective>>,
 802
 803     // The module children of this node, including normal modules and anonymous modules.
 804     // Anonymous children are pseudo-modules that are implicitly created around items
 805     // contained within blocks.
 806     //
 807     // For example, if we have this:
 808     //
 809     //  fn f() {
 810     //      fn g() {
 811     //          ...
 812     //      }
 813     //  }
 814     //
 815     // There will be an anonymous module created around `g` with the ID of the
 816     // entry block for `f`.
 817     module_children: RefCell<NodeMap<Module<'a>>>,
 818
 819     shadowed_traits: RefCell<Vec<&'a NameBinding<'a>>>,
 820
 821     // The number of unresolved globs that this module exports.
 822     glob_count: Cell<usize>,
 823
 824     // The number of unresolved pub imports (both regular and globs) in this module
 825     pub_count: Cell<usize>,
 826
 827     // The number of unresolved pub glob imports in this module
 828     pub_glob_count: Cell<usize>,
 829
 830     // The index of the import we're resolving.
 831     resolved_import_count: Cell<usize>,
 832
 833     // Whether this module is populated. If not populated, any attempt to
 834     // access the children must be preceded with a
 835     // `populate_module_if_necessary` call.
 836     populated: Cell<bool>,
 837 }
 838
 839 pub type Module<'a> = &'a ModuleS<'a>;
 840
 841 impl<'a> ModuleS<'a> {
 842     fn new(parent_link: ParentLink<'a>, def: Option<Def>, external: bool, is_public: bool) -> Self {
 843         ModuleS {
 844             parent_link: parent_link,
 845             def: def,
 846             is_public: is_public,
 847             is_extern_crate: false,
 848             resolutions: RefCell::new(HashMap::new()),
 849             imports: RefCell::new(Vec::new()),
 850             module_children: RefCell::new(NodeMap()),
 851             shadowed_traits: RefCell::new(Vec::new()),
 852             glob_count: Cell::new(0),
 853             pub_count: Cell::new(0),
 854             pub_glob_count: Cell::new(0),
 855             resolved_import_count: Cell::new(0),
 856             populated: Cell::new(!external),
 857         }
 858     }
 859
 860     fn resolve_name(&self, name: Name, ns: Namespace, allow_private_imports: bool)
 861                     -> ResolveResult<&'a NameBinding<'a>> {
 862         let glob_count =
 863             if allow_private_imports { self.glob_count.get() } else { self.pub_glob_count.get() };
 864
 865         self.resolutions.borrow().get(&(name, ns)).cloned().unwrap_or_default().result(glob_count)
 866             .and_then(|binding| {
 867                 let allowed = allow_private_imports || !binding.is_import() || binding.is_public();
 868                 if allowed { Success(binding) } else { Failed(None) }
 869             })
 870     }
 871
 872     // Define the name or return the existing binding if there is a collision.
 873     fn try_define_child(&self, name: Name, ns: Namespace, binding: &'a NameBinding<'a>)
 874                         -> Result<(), &'a NameBinding<'a>> {
 875         let mut children = self.resolutions.borrow_mut();
 876         let resolution = children.entry((name, ns)).or_insert_with(Default::default);
 877
 878         // FIXME #31379: We can use methods from imported traits shadowed by non-import items
 879         if let Some(old_binding) = resolution.binding {
 880             if !old_binding.is_import() && binding.is_import() {
 881                 if let Some(Def::Trait(_)) = binding.def() {
 882                     self.shadowed_traits.borrow_mut().push(binding);
 883                 }
 884             }
 885         }
 886
 887         resolution.try_define(binding)
 888     }
 889
 890     fn increment_outstanding_references_for(&self, name: Name, ns: Namespace) {
 891         let mut children = self.resolutions.borrow_mut();
 892         children.entry((name, ns)).or_insert_with(Default::default).outstanding_references += 1;
 893     }
 894
 895     fn decrement_outstanding_references_for(&self, name: Name, ns: Namespace) {
 896         match self.resolutions.borrow_mut().get_mut(&(name, ns)).unwrap().outstanding_references {
 897             0 => panic!("No more outstanding references!"),
 898             ref mut outstanding_references => { *outstanding_references -= 1; }
 899         }
 900     }
 901
 902     fn for_each_child<F: FnMut(Name, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 903         for (&(name, ns), name_resolution) in self.resolutions.borrow().iter() {
 904             name_resolution.binding.map(|binding| f(name, ns, binding));
 905         }
 906     }
 907
 908     fn def_id(&self) -> Option<DefId> {
 909         self.def.as_ref().map(Def::def_id)
 910     }
 911
 912     fn is_normal(&self) -> bool {
 913         match self.def {
 914             Some(Def::Mod(_)) | Some(Def::ForeignMod(_)) => true,
 915             _ => false,
 916         }
 917     }
 918
 919     fn is_trait(&self) -> bool {
 920         match self.def {
 921             Some(Def::Trait(_)) => true,
 922             _ => false,
 923         }
 924     }
 925
 926     fn all_imports_resolved(&self) -> bool {
 927         if self.imports.borrow_state() == ::std::cell::BorrowState::Writing {
 928             // it is currently being resolved ! so nope
 929             false
 930         } else {
 931             self.imports.borrow().len() == self.resolved_import_count.get()
 932         }
 933     }
 934
 935     pub fn inc_glob_count(&self) {
 936         self.glob_count.set(self.glob_count.get() + 1);
 937     }
 938     pub fn dec_glob_count(&self) {
 939         assert!(self.glob_count.get() > 0);
 940         self.glob_count.set(self.glob_count.get() - 1);
 941     }
 942     pub fn inc_pub_count(&self) {
 943         self.pub_count.set(self.pub_count.get() + 1);
 944     }
 945     pub fn dec_pub_count(&self) {
 946         assert!(self.pub_count.get() > 0);
 947         self.pub_count.set(self.pub_count.get() - 1);
 948     }
 949     pub fn inc_pub_glob_count(&self) {
 950         self.pub_glob_count.set(self.pub_glob_count.get() + 1);
 951     }
 952     pub fn dec_pub_glob_count(&self) {
 953         assert!(self.pub_glob_count.get() > 0);
 954         self.pub_glob_count.set(self.pub_glob_count.get() - 1);
 955     }
 956 }
 957
 958 impl<'a> fmt::Debug for ModuleS<'a> {
 959     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 960         write!(f,
 961                "{:?}, {}",
 962                self.def,
 963                if self.is_public {
 964                    "public"
 965                } else {
 966                    "private"
 967                })
 968     }
 969 }
 970
 971 bitflags! {
 972     #[derive(Debug)]
 973     flags DefModifiers: u8 {
 974         // Enum variants are always considered `PUBLIC`, this is needed for `use Enum::Variant`
 975         // or `use Enum::*` to work on private enums.
 976         const PUBLIC     = 1 << 0,
 977         const IMPORTABLE = 1 << 1,
 978         // Variants are considered `PUBLIC`, but some of them live in private enums.
 979         // We need to track them to prohibit reexports like `pub use PrivEnum::Variant`.
 980         const PRIVATE_VARIANT = 1 << 2,
 981         const PRELUDE = 1 << 3,
 982         const GLOB_IMPORTED = 1 << 4,
 983     }
 984 }
 985
 986 // Records a possibly-private value, type, or module definition.
 987 #[derive(Debug)]
 988 pub struct NameBinding<'a> {
 989     modifiers: DefModifiers,
 990     kind: NameBindingKind<'a>,
 991     span: Option<Span>,
 992 }
 993
 994 #[derive(Debug)]
 995 enum NameBindingKind<'a> {
 996     Def(Def),
 997     Module(Module<'a>),
 998     Import {
 999         binding: &'a NameBinding<'a>,
1000         id: NodeId,
1001     },
1002 }
1003
1004 impl<'a> NameBinding<'a> {
1005     fn create_from_module(module: Module<'a>, span: Option<Span>) -> Self {
1006         let modifiers = if module.is_public {
1007             DefModifiers::PUBLIC
1008         } else {
1009             DefModifiers::empty()
1010         } | DefModifiers::IMPORTABLE;
1011
1012         NameBinding { modifiers: modifiers, kind: NameBindingKind::Module(module), span: span }
1013     }
1014
1015     fn module(&self) -> Option<Module<'a>> {
1016         match self.kind {
1017             NameBindingKind::Module(module) => Some(module),
1018             NameBindingKind::Def(_) => None,
1019             NameBindingKind::Import { binding, .. } => binding.module(),
1020         }
1021     }
1022
1023     fn def(&self) -> Option<Def> {
1024         match self.kind {
1025             NameBindingKind::Def(def) => Some(def),
1026             NameBindingKind::Module(module) => module.def,
1027             NameBindingKind::Import { binding, .. } => binding.def(),
1028         }
1029     }
1030
1031     fn defined_with(&self, modifiers: DefModifiers) -> bool {
1032         self.modifiers.contains(modifiers)
1033     }
1034
1035     fn is_public(&self) -> bool {
1036         self.defined_with(DefModifiers::PUBLIC)
1037     }
1038
1039     fn def_and_lp(&self) -> (Def, LastPrivate) {
1040         let def = self.def().unwrap();
1041         if let Def::Err = def { return (def, LastMod(AllPublic)) }
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                 PatKind::Ident(binding_mode, ref path1, ref at_rhs) => {
2327                     // The meaning of PatKind::Ident 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                 PatKind::TupleStruct(ref path, _) | PatKind::Path(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 PatKind::QPath.
2447                         TypecheckRequired =>
2448                             self.session.span_bug(path.span,
2449                                                   "resolve_possibly_assoc_item claimed that a path \
2450                                                    in PatKind::Path or PatKind::TupleStruct \
2451                                                    requires typecheck to resolve, but qualified \
2452                                                    paths should be PatKind::QPath"),
2453                         ResolveAttempt(resolution) => resolution,
2454                     };
2455                     if let Some(path_res) = resolution {
2456                         match path_res.base_def {
2457                             Def::Struct(..) if path_res.depth == 0 => {
2458                                 self.record_def(pattern.id, path_res);
2459                             }
2460                             Def::Variant(..) | Def::Const(..) => {
2461                                 self.record_def(pattern.id, path_res);
2462                             }
2463                             Def::Static(..) => {
2464                                 resolve_error(&self,
2465                                               path.span,
2466                                               ResolutionError::StaticVariableReference);
2467                                 self.record_def(pattern.id, err_path_resolution());
2468                             }
2469                             _ => {
2470                                 // If anything ends up here entirely resolved,
2471                                 // it's an error. If anything ends up here
2472                                 // partially resolved, that's OK, because it may
2473                                 // be a `T::CONST` that typeck will resolve.
2474                                 if path_res.depth == 0 {
2475                                     resolve_error(
2476                                         self,
2477                                         path.span,
2478                                         ResolutionError::NotAnEnumVariantStructOrConst(
2479                                             &path.segments
2480                                                  .last()
2481                                                  .unwrap()
2482                                                  .identifier
2483                                                  .name
2484                                                  .as_str())
2485                                     );
2486                                     self.record_def(pattern.id, err_path_resolution());
2487                                 } else {
2488                                     let const_name = path.segments
2489                                                          .last()
2490                                                          .unwrap()
2491                                                          .identifier
2492                                                          .name;
2493                                     let traits = self.get_traits_containing_item(const_name);
2494                                     self.trait_map.insert(pattern.id, traits);
2495                                     self.record_def(pattern.id, path_res);
2496                                 }
2497                             }
2498                         }
2499                     } else {
2500                         resolve_error(
2501                             self,
2502                             path.span,
2503                             ResolutionError::UnresolvedEnumVariantStructOrConst(
2504                                 &path.segments.last().unwrap().identifier.name.as_str())
2505                         );
2506                         self.record_def(pattern.id, err_path_resolution());
2507                     }
2508                     intravisit::walk_path(self, path);
2509                 }
2510
2511                 PatKind::QPath(ref qself, ref path) => {
2512                     // Associated constants only.
2513                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2514                                                                             Some(qself),
2515                                                                             path,
2516                                                                             ValueNS,
2517                                                                             false) {
2518                         TypecheckRequired => {
2519                             // All `<T>::CONST` should end up here, and will
2520                             // require use of the trait map to resolve
2521                             // during typechecking.
2522                             let const_name = path.segments
2523                                                  .last()
2524                                                  .unwrap()
2525                                                  .identifier
2526                                                  .name;
2527                             let traits = self.get_traits_containing_item(const_name);
2528                             self.trait_map.insert(pattern.id, traits);
2529                             intravisit::walk_pat(self, pattern);
2530                             return true;
2531                         }
2532                         ResolveAttempt(resolution) => resolution,
2533                     };
2534                     if let Some(path_res) = resolution {
2535                         match path_res.base_def {
2536                             // All `<T as Trait>::CONST` should end up here, and
2537                             // have the trait already selected.
2538                             Def::AssociatedConst(..) => {
2539                                 self.record_def(pattern.id, path_res);
2540                             }
2541                             _ => {
2542                                 resolve_error(
2543                                     self,
2544                                     path.span,
2545                                     ResolutionError::NotAnAssociatedConst(
2546                                         &path.segments.last().unwrap().identifier.name.as_str()
2547                                     )
2548                                 );
2549                                 self.record_def(pattern.id, err_path_resolution());
2550                             }
2551                         }
2552                     } else {
2553                         resolve_error(self,
2554                                       path.span,
2555                                       ResolutionError::UnresolvedAssociatedConst(&path.segments
2556                                                                                       .last()
2557                                                                                       .unwrap()
2558                                                                                       .identifier
2559                                                                                       .name
2560                                                                                       .as_str()));
2561                         self.record_def(pattern.id, err_path_resolution());
2562                     }
2563                     intravisit::walk_pat(self, pattern);
2564                 }
2565
2566                 PatKind::Struct(ref path, _, _) => {
2567                     match self.resolve_path(pat_id, path, 0, TypeNS, false) {
2568                         Some(definition) => {
2569                             self.record_def(pattern.id, definition);
2570                         }
2571                         result => {
2572                             debug!("(resolving pattern) didn't find struct def: {:?}", result);
2573                             resolve_error(
2574                                 self,
2575                                 path.span,
2576                                 ResolutionError::DoesNotNameAStruct(
2577                                     &path_names_to_string(path, 0))
2578                             );
2579                             self.record_def(pattern.id, err_path_resolution());
2580                         }
2581                     }
2582                     intravisit::walk_path(self, path);
2583                 }
2584
2585                 PatKind::Lit(_) | PatKind::Range(..) => {
2586                     intravisit::walk_pat(self, pattern);
2587                 }
2588
2589                 _ => {
2590                     // Nothing to do.
2591                 }
2592             }
2593             true
2594         });
2595     }
2596
2597     fn resolve_bare_identifier_pattern(&mut self,
2598                                        name: Name,
2599                                        span: Span)
2600                                        -> BareIdentifierPatternResolution {
2601         let module = self.current_module;
2602         match self.resolve_item_in_lexical_scope(module, name, ValueNS, true) {
2603             Success(binding) => {
2604                 debug!("(resolve bare identifier pattern) succeeded in finding {} at {:?}",
2605                        name,
2606                        binding);
2607                 match binding.def() {
2608                     None => {
2609                         panic!("resolved name in the value namespace to a set of name bindings \
2610                                 with no def?!");
2611                     }
2612                     // For the two success cases, this lookup can be
2613                     // considered as not having a private component because
2614                     // the lookup happened only within the current module.
2615                     Some(def @ Def::Variant(..)) | Some(def @ Def::Struct(..)) => {
2616                         return FoundStructOrEnumVariant(def, LastMod(AllPublic));
2617                     }
2618                     Some(def @ Def::Const(..)) | Some(def @ Def::AssociatedConst(..)) => {
2619                         return FoundConst(def, LastMod(AllPublic), name);
2620                     }
2621                     Some(Def::Static(..)) => {
2622                         resolve_error(self, span, ResolutionError::StaticVariableReference);
2623                         return BareIdentifierPatternUnresolved;
2624                     }
2625                     _ => return BareIdentifierPatternUnresolved
2626                 }
2627             }
2628
2629             Indeterminate => return BareIdentifierPatternUnresolved,
2630             Failed(err) => {
2631                 match err {
2632                     Some((span, msg)) => {
2633                         resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2634                     }
2635                     None => (),
2636                 }
2637
2638                 debug!("(resolve bare identifier pattern) failed to find {}", name);
2639                 return BareIdentifierPatternUnresolved;
2640             }
2641         }
2642     }
2643
2644     /// Handles paths that may refer to associated items
2645     fn resolve_possibly_assoc_item(&mut self,
2646                                    id: NodeId,
2647                                    maybe_qself: Option<&hir::QSelf>,
2648                                    path: &Path,
2649                                    namespace: Namespace,
2650                                    check_ribs: bool)
2651                                    -> AssocItemResolveResult {
2652         let max_assoc_types;
2653
2654         match maybe_qself {
2655             Some(qself) => {
2656                 if qself.position == 0 {
2657                     return TypecheckRequired;
2658                 }
2659                 max_assoc_types = path.segments.len() - qself.position;
2660                 // Make sure the trait is valid.
2661                 let _ = self.resolve_trait_reference(id, path, max_assoc_types);
2662             }
2663             None => {
2664                 max_assoc_types = path.segments.len();
2665             }
2666         }
2667
2668         let mut resolution = self.with_no_errors(|this| {
2669             this.resolve_path(id, path, 0, namespace, check_ribs)
2670         });
2671         for depth in 1..max_assoc_types {
2672             if resolution.is_some() {
2673                 break;
2674             }
2675             self.with_no_errors(|this| {
2676                 resolution = this.resolve_path(id, path, depth, TypeNS, true);
2677             });
2678         }
2679         if let Some(Def::Mod(_)) = resolution.map(|r| r.base_def) {
2680             // A module is not a valid type or value.
2681             resolution = None;
2682         }
2683         ResolveAttempt(resolution)
2684     }
2685
2686     /// If `check_ribs` is true, checks the local definitions first; i.e.
2687     /// doesn't skip straight to the containing module.
2688     /// Skips `path_depth` trailing segments, which is also reflected in the
2689     /// returned value. See `middle::def::PathResolution` for more info.
2690     pub fn resolve_path(&mut self,
2691                         id: NodeId,
2692                         path: &Path,
2693                         path_depth: usize,
2694                         namespace: Namespace,
2695                         check_ribs: bool)
2696                         -> Option<PathResolution> {
2697         let span = path.span;
2698         let segments = &path.segments[..path.segments.len() - path_depth];
2699
2700         let mk_res = |(def, lp)| PathResolution::new(def, lp, path_depth);
2701
2702         if path.global {
2703             let def = self.resolve_crate_relative_path(span, segments, namespace);
2704             return def.map(mk_res);
2705         }
2706
2707         // Try to find a path to an item in a module.
2708         let last_ident = segments.last().unwrap().identifier;
2709         if segments.len() <= 1 {
2710             let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, true);
2711             return unqualified_def.and_then(|def| self.adjust_local_def(def, span))
2712                                   .map(|def| {
2713                                       PathResolution::new(def, LastMod(AllPublic), path_depth)
2714                                   });
2715         }
2716
2717         let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, false);
2718         let def = self.resolve_module_relative_path(span, segments, namespace);
2719         match (def, unqualified_def) {
2720             (Some((ref d, _)), Some(ref ud)) if *d == ud.def => {
2721                 self.session
2722                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
2723                               id,
2724                               span,
2725                               "unnecessary qualification".to_string());
2726             }
2727             _ => {}
2728         }
2729
2730         def.map(mk_res)
2731     }
2732
2733     // Resolve a single identifier
2734     fn resolve_identifier(&mut self,
2735                           identifier: hir::Ident,
2736                           namespace: Namespace,
2737                           check_ribs: bool,
2738                           record_used: bool)
2739                           -> Option<LocalDef> {
2740         if identifier.name == special_idents::invalid.name {
2741             return Some(LocalDef::from_def(Def::Err));
2742         }
2743
2744         // First, check to see whether the name is a primitive type.
2745         if namespace == TypeNS {
2746             if let Some(&prim_ty) = self.primitive_type_table
2747                                         .primitive_types
2748                                         .get(&identifier.unhygienic_name) {
2749                 return Some(LocalDef::from_def(Def::PrimTy(prim_ty)));
2750             }
2751         }
2752
2753         if check_ribs {
2754             if let Some(def) = self.resolve_identifier_in_local_ribs(identifier, namespace) {
2755                 return Some(def);
2756             }
2757         }
2758
2759         // Check the items.
2760         let module = self.current_module;
2761         let name = identifier.unhygienic_name;
2762         match self.resolve_item_in_lexical_scope(module, name, namespace, record_used) {
2763             Success(binding) => binding.def().map(LocalDef::from_def),
2764             Failed(Some((span, msg))) => {
2765                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2766                 None
2767             }
2768             _ => None,
2769         }
2770     }
2771
2772     // Resolve a local definition, potentially adjusting for closures.
2773     fn adjust_local_def(&mut self, local_def: LocalDef, span: Span) -> Option<Def> {
2774         let ribs = match local_def.ribs {
2775             Some((TypeNS, i)) => &self.type_ribs[i + 1..],
2776             Some((ValueNS, i)) => &self.value_ribs[i + 1..],
2777             _ => &[] as &[_],
2778         };
2779         let mut def = local_def.def;
2780         match def {
2781             Def::Upvar(..) => {
2782                 self.session.span_bug(span, &format!("unexpected {:?} in bindings", def))
2783             }
2784             Def::Local(_, node_id) => {
2785                 for rib in ribs {
2786                     match rib.kind {
2787                         NormalRibKind | AnonymousModuleRibKind(..) => {
2788                             // Nothing to do. Continue.
2789                         }
2790                         ClosureRibKind(function_id) => {
2791                             let prev_def = def;
2792                             let node_def_id = self.ast_map.local_def_id(node_id);
2793
2794                             let seen = self.freevars_seen
2795                                            .entry(function_id)
2796                                            .or_insert_with(|| NodeMap());
2797                             if let Some(&index) = seen.get(&node_id) {
2798                                 def = Def::Upvar(node_def_id, node_id, index, function_id);
2799                                 continue;
2800                             }
2801                             let vec = self.freevars
2802                                           .entry(function_id)
2803                                           .or_insert_with(|| vec![]);
2804                             let depth = vec.len();
2805                             vec.push(Freevar {
2806                                 def: prev_def,
2807                                 span: span,
2808                             });
2809
2810                             def = Def::Upvar(node_def_id, node_id, depth, function_id);
2811                             seen.insert(node_id, depth);
2812                         }
2813                         ItemRibKind | MethodRibKind => {
2814                             // This was an attempt to access an upvar inside a
2815                             // named function item. This is not allowed, so we
2816                             // report an error.
2817                             resolve_error(self,
2818                                           span,
2819                                           ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2820                             return None;
2821                         }
2822                         ConstantItemRibKind => {
2823                             // Still doesn't deal with upvars
2824                             resolve_error(self,
2825                                           span,
2826                                           ResolutionError::AttemptToUseNonConstantValueInConstant);
2827                             return None;
2828                         }
2829                     }
2830                 }
2831             }
2832             Def::TyParam(..) | Def::SelfTy(..) => {
2833                 for rib in ribs {
2834                     match rib.kind {
2835                         NormalRibKind | MethodRibKind | ClosureRibKind(..) |
2836                         AnonymousModuleRibKind(..) => {
2837                             // Nothing to do. Continue.
2838                         }
2839                         ItemRibKind => {
2840                             // This was an attempt to use a type parameter outside
2841                             // its scope.
2842
2843                             resolve_error(self,
2844                                           span,
2845                                           ResolutionError::TypeParametersFromOuterFunction);
2846                             return None;
2847                         }
2848                         ConstantItemRibKind => {
2849                             // see #9186
2850                             resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
2851                             return None;
2852                         }
2853                     }
2854                 }
2855             }
2856             _ => {}
2857         }
2858         return Some(def);
2859     }
2860
2861     // resolve a "module-relative" path, e.g. a::b::c
2862     fn resolve_module_relative_path(&mut self,
2863                                     span: Span,
2864                                     segments: &[hir::PathSegment],
2865                                     namespace: Namespace)
2866                                     -> Option<(Def, LastPrivate)> {
2867         let module_path = segments.split_last()
2868                                   .unwrap()
2869                                   .1
2870                                   .iter()
2871                                   .map(|ps| ps.identifier.name)
2872                                   .collect::<Vec<_>>();
2873
2874         let containing_module;
2875         let last_private;
2876         let current_module = self.current_module;
2877         match self.resolve_module_path(current_module, &module_path, UseLexicalScope, span) {
2878             Failed(err) => {
2879                 let (span, msg) = match err {
2880                     Some((span, msg)) => (span, msg),
2881                     None => {
2882                         let msg = format!("Use of undeclared type or module `{}`",
2883                                           names_to_string(&module_path));
2884                         (span, msg)
2885                     }
2886                 };
2887
2888                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2889                 return None;
2890             }
2891             Indeterminate => return None,
2892             Success((resulting_module, resulting_last_private)) => {
2893                 containing_module = resulting_module;
2894                 last_private = resulting_last_private;
2895             }
2896         }
2897
2898         let name = segments.last().unwrap().identifier.name;
2899         let result = self.resolve_name_in_module(containing_module, name, namespace, false, true);
2900         let def = match result {
2901             Success(binding) => {
2902                 let (def, lp) = binding.def_and_lp();
2903                 (def, last_private.or(lp))
2904             }
2905             _ => return None,
2906         };
2907         return Some(def);
2908     }
2909
2910     /// Invariant: This must be called only during main resolution, not during
2911     /// import resolution.
2912     fn resolve_crate_relative_path(&mut self,
2913                                    span: Span,
2914                                    segments: &[hir::PathSegment],
2915                                    namespace: Namespace)
2916                                    -> Option<(Def, LastPrivate)> {
2917         let module_path = segments.split_last()
2918                                   .unwrap()
2919                                   .1
2920                                   .iter()
2921                                   .map(|ps| ps.identifier.name)
2922                                   .collect::<Vec<_>>();
2923
2924         let root_module = self.graph_root;
2925
2926         let containing_module;
2927         let last_private;
2928         match self.resolve_module_path_from_root(root_module,
2929                                                  &module_path,
2930                                                  0,
2931                                                  span,
2932                                                  LastMod(AllPublic)) {
2933             Failed(err) => {
2934                 let (span, msg) = match err {
2935                     Some((span, msg)) => (span, msg),
2936                     None => {
2937                         let msg = format!("Use of undeclared module `::{}`",
2938                                           names_to_string(&module_path));
2939                         (span, msg)
2940                     }
2941                 };
2942
2943                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2944                 return None;
2945             }
2946
2947             Indeterminate => return None,
2948
2949             Success((resulting_module, resulting_last_private)) => {
2950                 containing_module = resulting_module;
2951                 last_private = resulting_last_private;
2952             }
2953         }
2954
2955         let name = segments.last().unwrap().identifier.name;
2956         match self.resolve_name_in_module(containing_module, name, namespace, false, true) {
2957             Success(binding) => {
2958                 let (def, lp) = binding.def_and_lp();
2959                 Some((def, last_private.or(lp)))
2960             }
2961             _ => None,
2962         }
2963     }
2964
2965     fn resolve_identifier_in_local_ribs(&mut self,
2966                                         ident: hir::Ident,
2967                                         namespace: Namespace)
2968                                         -> Option<LocalDef> {
2969         // Check the local set of ribs.
2970         let name = match namespace { ValueNS => ident.name, TypeNS => ident.unhygienic_name };
2971
2972         for i in (0 .. self.get_ribs(namespace).len()).rev() {
2973             if let Some(def_like) = self.get_ribs(namespace)[i].bindings.get(&name).cloned() {
2974                 match def_like {
2975                     DlDef(def) => {
2976                         debug!("(resolving path in local ribs) resolved `{}` to {:?} at {}",
2977                                name,
2978                                def,
2979                                i);
2980                         return Some(LocalDef {
2981                             ribs: Some((namespace, i)),
2982                             def: def,
2983                         });
2984                     }
2985                     def_like => {
2986                         debug!("(resolving path in local ribs) resolved `{}` to pseudo-def {:?}",
2987                                name,
2988                                def_like);
2989                         return None;
2990                     }
2991                 }
2992             }
2993
2994             if let AnonymousModuleRibKind(module) = self.get_ribs(namespace)[i].kind {
2995                 if let Success(binding) = self.resolve_name_in_module(module,
2996                                                                       ident.unhygienic_name,
2997                                                                       namespace,
2998                                                                       true,
2999                                                                       true) {
3000                     if let Some(def) = binding.def() {
3001                         return Some(LocalDef::from_def(def));
3002                     }
3003                 }
3004             }
3005         }
3006
3007         None
3008     }
3009
3010     fn with_no_errors<T, F>(&mut self, f: F) -> T
3011         where F: FnOnce(&mut Resolver) -> T
3012     {
3013         self.emit_errors = false;
3014         let rs = f(self);
3015         self.emit_errors = true;
3016         rs
3017     }
3018
3019     fn find_fallback_in_self_type(&mut self, name: Name) -> FallbackSuggestion {
3020         fn extract_path_and_node_id(t: &Ty,
3021                                     allow: FallbackChecks)
3022                                     -> Option<(Path, NodeId, FallbackChecks)> {
3023             match t.node {
3024                 TyPath(None, ref path) => Some((path.clone(), t.id, allow)),
3025                 TyPtr(ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, OnlyTraitAndStatics),
3026                 TyRptr(_, ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, allow),
3027                 // This doesn't handle the remaining `Ty` variants as they are not
3028                 // that commonly the self_type, it might be interesting to provide
3029                 // support for those in future.
3030                 _ => None,
3031             }
3032         }
3033
3034         fn get_module<'a, 'tcx>(this: &mut Resolver<'a, 'tcx>,
3035                                 span: Span,
3036                                 name_path: &[ast::Name])
3037                                 -> Option<Module<'a>> {
3038             let root = this.current_module;
3039             let last_name = name_path.last().unwrap();
3040
3041             if name_path.len() == 1 {
3042                 match this.primitive_type_table.primitive_types.get(last_name) {
3043                     Some(_) => None,
3044                     None => this.current_module.resolve_name(*last_name, TypeNS, true).success()
3045                                                .and_then(NameBinding::module)
3046                 }
3047             } else {
3048                 match this.resolve_module_path(root, &name_path, UseLexicalScope, span) {
3049                     Success((module, _)) => Some(module),
3050                     _ => None,
3051                 }
3052             }
3053         }
3054
3055         fn is_static_method(this: &Resolver, did: DefId) -> bool {
3056             if let Some(node_id) = this.ast_map.as_local_node_id(did) {
3057                 let sig = match this.ast_map.get(node_id) {
3058                     hir_map::NodeTraitItem(trait_item) => match trait_item.node {
3059                         hir::MethodTraitItem(ref sig, _) => sig,
3060                         _ => return false,
3061                     },
3062                     hir_map::NodeImplItem(impl_item) => match impl_item.node {
3063                         hir::ImplItemKind::Method(ref sig, _) => sig,
3064                         _ => return false,
3065                     },
3066                     _ => return false,
3067                 };
3068                 sig.explicit_self.node == hir::SelfStatic
3069             } else {
3070                 this.session.cstore.is_static_method(did)
3071             }
3072         }
3073
3074         let (path, node_id, allowed) = match self.current_self_type {
3075             Some(ref ty) => match extract_path_and_node_id(ty, Everything) {
3076                 Some(x) => x,
3077                 None => return NoSuggestion,
3078             },
3079             None => return NoSuggestion,
3080         };
3081
3082         if allowed == Everything {
3083             // Look for a field with the same name in the current self_type.
3084             match self.def_map.borrow().get(&node_id).map(|d| d.full_def()) {
3085                 Some(Def::Enum(did)) |
3086                 Some(Def::TyAlias(did)) |
3087                 Some(Def::Struct(did)) |
3088                 Some(Def::Variant(_, did)) => match self.structs.get(&did) {
3089                     None => {}
3090                     Some(fields) => {
3091                         if fields.iter().any(|&field_name| name == field_name) {
3092                             return Field;
3093                         }
3094                     }
3095                 },
3096                 _ => {} // Self type didn't resolve properly
3097             }
3098         }
3099
3100         let name_path = path.segments.iter().map(|seg| seg.identifier.name).collect::<Vec<_>>();
3101
3102         // Look for a method in the current self type's impl module.
3103         if let Some(module) = get_module(self, path.span, &name_path) {
3104             if let Success(binding) = module.resolve_name(name, ValueNS, true) {
3105                 if let Some(Def::Method(did)) = binding.def() {
3106                     if is_static_method(self, did) {
3107                         return StaticMethod(path_names_to_string(&path, 0));
3108                     }
3109                     if self.current_trait_ref.is_some() {
3110                         return TraitItem;
3111                     } else if allowed == Everything {
3112                         return Method;
3113                     }
3114                 }
3115             }
3116         }
3117
3118         // Look for a method in the current trait.
3119         if let Some((trait_did, ref trait_ref)) = self.current_trait_ref {
3120             if let Some(&did) = self.trait_item_map.get(&(name, trait_did)) {
3121                 if is_static_method(self, did) {
3122                     return TraitMethod(path_names_to_string(&trait_ref.path, 0));
3123                 } else {
3124                     return TraitItem;
3125                 }
3126             }
3127         }
3128
3129         NoSuggestion
3130     }
3131
3132     fn find_best_match(&mut self, name: &str) -> SuggestionType {
3133         if let Some(macro_name) = self.session.available_macros
3134                                   .borrow().iter().find(|n| n.as_str() == name) {
3135             return SuggestionType::Macro(format!("{}!", macro_name));
3136         }
3137
3138         let names = self.value_ribs
3139                     .iter()
3140                     .rev()
3141                     .flat_map(|rib| rib.bindings.keys());
3142
3143         if let Some(found) = find_best_match_for_name(names, name, None) {
3144             if name != found {
3145                 return SuggestionType::Function(found);
3146             }
3147         } SuggestionType::NotFound
3148     }
3149
3150     fn resolve_expr(&mut self, expr: &Expr) {
3151         // First, record candidate traits for this expression if it could
3152         // result in the invocation of a method call.
3153
3154         self.record_candidate_traits_for_expr_if_necessary(expr);
3155
3156         // Next, resolve the node.
3157         match expr.node {
3158             ExprPath(ref maybe_qself, ref path) => {
3159                 let resolution = match self.resolve_possibly_assoc_item(expr.id,
3160                                                                         maybe_qself.as_ref(),
3161                                                                         path,
3162                                                                         ValueNS,
3163                                                                         true) {
3164                     // `<T>::a::b::c` is resolved by typeck alone.
3165                     TypecheckRequired => {
3166                         let method_name = path.segments.last().unwrap().identifier.name;
3167                         let traits = self.get_traits_containing_item(method_name);
3168                         self.trait_map.insert(expr.id, traits);
3169                         intravisit::walk_expr(self, expr);
3170                         return;
3171                     }
3172                     ResolveAttempt(resolution) => resolution,
3173                 };
3174
3175                 // This is a local path in the value namespace. Walk through
3176                 // scopes looking for it.
3177                 if let Some(path_res) = resolution {
3178                     // Check if struct variant
3179                     let is_struct_variant = if let Def::Variant(_, variant_id) = path_res.base_def {
3180                         self.structs.contains_key(&variant_id)
3181                     } else {
3182                         false
3183                     };
3184                     if is_struct_variant {
3185                         let _ = self.structs.contains_key(&path_res.base_def.def_id());
3186                         let path_name = path_names_to_string(path, 0);
3187
3188                         let mut err = resolve_struct_error(self,
3189                                         expr.span,
3190                                         ResolutionError::StructVariantUsedAsFunction(&path_name));
3191
3192                         let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3193                                           path_name);
3194                         if self.emit_errors {
3195                             err.fileline_help(expr.span, &msg);
3196                         } else {
3197                             err.span_help(expr.span, &msg);
3198                         }
3199                         err.emit();
3200                         self.record_def(expr.id, err_path_resolution());
3201                     } else {
3202                         // Write the result into the def map.
3203                         debug!("(resolving expr) resolved `{}`",
3204                                path_names_to_string(path, 0));
3205
3206                         // Partial resolutions will need the set of traits in scope,
3207                         // so they can be completed during typeck.
3208                         if path_res.depth != 0 {
3209                             let method_name = path.segments.last().unwrap().identifier.name;
3210                             let traits = self.get_traits_containing_item(method_name);
3211                             self.trait_map.insert(expr.id, traits);
3212                         }
3213
3214                         self.record_def(expr.id, path_res);
3215                     }
3216                 } else {
3217                     // Be helpful if the name refers to a struct
3218                     // (The pattern matching def_tys where the id is in self.structs
3219                     // matches on regular structs while excluding tuple- and enum-like
3220                     // structs, which wouldn't result in this error.)
3221                     let path_name = path_names_to_string(path, 0);
3222                     let type_res = self.with_no_errors(|this| {
3223                         this.resolve_path(expr.id, path, 0, TypeNS, false)
3224                     });
3225
3226                     self.record_def(expr.id, err_path_resolution());
3227                     match type_res.map(|r| r.base_def) {
3228                         Some(Def::Struct(..)) => {
3229                             let mut err = resolve_struct_error(self,
3230                                 expr.span,
3231                                 ResolutionError::StructVariantUsedAsFunction(&path_name));
3232
3233                             let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3234                                               path_name);
3235                             if self.emit_errors {
3236                                 err.fileline_help(expr.span, &msg);
3237                             } else {
3238                                 err.span_help(expr.span, &msg);
3239                             }
3240                             err.emit();
3241                         }
3242                         _ => {
3243                             // Keep reporting some errors even if they're ignored above.
3244                             self.resolve_path(expr.id, path, 0, ValueNS, true);
3245
3246                             let mut method_scope = false;
3247                             self.value_ribs.iter().rev().all(|rib| {
3248                                 method_scope = match rib.kind {
3249                                     MethodRibKind => true,
3250                                     ItemRibKind | ConstantItemRibKind => false,
3251                                     _ => return true, // Keep advancing
3252                                 };
3253                                 false // Stop advancing
3254                             });
3255
3256                             if method_scope && special_names::self_.as_str() == &path_name[..] {
3257                                 resolve_error(self,
3258                                               expr.span,
3259                                               ResolutionError::SelfNotAvailableInStaticMethod);
3260                             } else {
3261                                 let last_name = path.segments.last().unwrap().identifier.name;
3262                                 let mut msg = match self.find_fallback_in_self_type(last_name) {
3263                                     NoSuggestion => {
3264                                         // limit search to 5 to reduce the number
3265                                         // of stupid suggestions
3266                                         match self.find_best_match(&path_name) {
3267                                             SuggestionType::Macro(s) => {
3268                                                 format!("the macro `{}`", s)
3269                                             }
3270                                             SuggestionType::Function(s) => format!("`{}`", s),
3271                                             SuggestionType::NotFound => "".to_string(),
3272                                         }
3273                                     }
3274                                     Field => format!("`self.{}`", path_name),
3275                                     Method |
3276                                     TraitItem => format!("to call `self.{}`", path_name),
3277                                     TraitMethod(path_str) |
3278                                     StaticMethod(path_str) =>
3279                                         format!("to call `{}::{}`", path_str, path_name),
3280                                 };
3281
3282                                 let mut context =  UnresolvedNameContext::Other;
3283                                 if !msg.is_empty() {
3284                                     msg = format!(". Did you mean {}?", msg);
3285                                 } else {
3286                                     // we check if this a module and if so, we display a help
3287                                     // message
3288                                     let name_path = path.segments.iter()
3289                                                         .map(|seg| seg.identifier.name)
3290                                                         .collect::<Vec<_>>();
3291                                     let current_module = self.current_module;
3292
3293                                     match self.resolve_module_path(current_module,
3294                                                                    &name_path[..],
3295                                                                    UseLexicalScope,
3296                                                                    expr.span) {
3297                                         Success(_) => {
3298                                             context = UnresolvedNameContext::PathIsMod(expr.id);
3299                                         },
3300                                         _ => {},
3301                                     };
3302                                 }
3303
3304                                 resolve_error(self,
3305                                               expr.span,
3306                                               ResolutionError::UnresolvedName(
3307                                                   &path_name, &msg, context));
3308                             }
3309                         }
3310                     }
3311                 }
3312
3313                 intravisit::walk_expr(self, expr);
3314             }
3315
3316             ExprStruct(ref path, _, _) => {
3317                 // Resolve the path to the structure it goes to. We don't
3318                 // check to ensure that the path is actually a structure; that
3319                 // is checked later during typeck.
3320                 match self.resolve_path(expr.id, path, 0, TypeNS, false) {
3321                     Some(definition) => self.record_def(expr.id, definition),
3322                     None => {
3323                         debug!("(resolving expression) didn't find struct def",);
3324
3325                         resolve_error(self,
3326                                       path.span,
3327                                       ResolutionError::DoesNotNameAStruct(
3328                                                                 &path_names_to_string(path, 0))
3329                                      );
3330                         self.record_def(expr.id, err_path_resolution());
3331                     }
3332                 }
3333
3334                 intravisit::walk_expr(self, expr);
3335             }
3336
3337             ExprLoop(_, Some(label)) | ExprWhile(_, _, Some(label)) => {
3338                 self.with_label_rib(|this| {
3339                     let def_like = DlDef(Def::Label(expr.id));
3340
3341                     {
3342                         let rib = this.label_ribs.last_mut().unwrap();
3343                         rib.bindings.insert(label.name, def_like);
3344                     }
3345
3346                     intravisit::walk_expr(this, expr);
3347                 })
3348             }
3349
3350             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
3351                 match self.search_label(label.node.name) {
3352                     None => {
3353                         self.record_def(expr.id, err_path_resolution());
3354                         resolve_error(self,
3355                                       label.span,
3356                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
3357                     }
3358                     Some(DlDef(def @ Def::Label(_))) => {
3359                         // Since this def is a label, it is never read.
3360                         self.record_def(expr.id,
3361                                         PathResolution {
3362                                             base_def: def,
3363                                             last_private: LastMod(AllPublic),
3364                                             depth: 0,
3365                                         })
3366                     }
3367                     Some(_) => {
3368                         self.session.span_bug(expr.span, "label wasn't mapped to a label def!")
3369                     }
3370                 }
3371             }
3372
3373             _ => {
3374                 intravisit::walk_expr(self, expr);
3375             }
3376         }
3377     }
3378
3379     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3380         match expr.node {
3381             ExprField(_, name) => {
3382                 // FIXME(#6890): Even though you can't treat a method like a
3383                 // field, we need to add any trait methods we find that match
3384                 // the field name so that we can do some nice error reporting
3385                 // later on in typeck.
3386                 let traits = self.get_traits_containing_item(name.node);
3387                 self.trait_map.insert(expr.id, traits);
3388             }
3389             ExprMethodCall(name, _, _) => {
3390                 debug!("(recording candidate traits for expr) recording traits for {}",
3391                        expr.id);
3392                 let traits = self.get_traits_containing_item(name.node);
3393                 self.trait_map.insert(expr.id, traits);
3394             }
3395             _ => {
3396                 // Nothing to do.
3397             }
3398         }
3399     }
3400
3401     fn get_traits_containing_item(&mut self, name: Name) -> Vec<DefId> {
3402         debug!("(getting traits containing item) looking for '{}'", name);
3403
3404         fn add_trait_info(found_traits: &mut Vec<DefId>, trait_def_id: DefId, name: Name) {
3405             debug!("(adding trait info) found trait {:?} for method '{}'",
3406                    trait_def_id,
3407                    name);
3408             found_traits.push(trait_def_id);
3409         }
3410
3411         let mut found_traits = Vec::new();
3412         let mut search_module = self.current_module;
3413         loop {
3414             // Look for the current trait.
3415             match self.current_trait_ref {
3416                 Some((trait_def_id, _)) => {
3417                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3418                         add_trait_info(&mut found_traits, trait_def_id, name);
3419                     }
3420                 }
3421                 None => {} // Nothing to do.
3422             }
3423
3424             // Look for trait children.
3425             build_reduced_graph::populate_module_if_necessary(self, &search_module);
3426
3427             search_module.for_each_child(|_, ns, name_binding| {
3428                 if ns != TypeNS { return }
3429                 let trait_def_id = match name_binding.def() {
3430                     Some(Def::Trait(trait_def_id)) => trait_def_id,
3431                     Some(..) | None => return,
3432                 };
3433                 if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3434                     add_trait_info(&mut found_traits, trait_def_id, name);
3435                     let trait_name = self.get_trait_name(trait_def_id);
3436                     self.record_use(trait_name, TypeNS, name_binding);
3437                 }
3438             });
3439
3440             // Look for shadowed traits.
3441             for binding in search_module.shadowed_traits.borrow().iter() {
3442                 let did = binding.def().unwrap().def_id();
3443                 if self.trait_item_map.contains_key(&(name, did)) {
3444                     add_trait_info(&mut found_traits, did, name);
3445                     let trait_name = self.get_trait_name(did);
3446                     self.record_use(trait_name, TypeNS, binding);
3447                 }
3448             }
3449
3450             match search_module.parent_link {
3451                 NoParentLink | ModuleParentLink(..) => break,
3452                 BlockParentLink(parent_module, _) => {
3453                     search_module = parent_module;
3454                 }
3455             }
3456         }
3457
3458         found_traits
3459     }
3460
3461     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3462         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3463         assert!(match resolution.last_private {
3464                     LastImport{..} => false,
3465                     _ => true,
3466                 },
3467                 "Import should only be used for `use` directives");
3468
3469         if let Some(prev_res) = self.def_map.borrow_mut().insert(node_id, resolution) {
3470             let span = self.ast_map.opt_span(node_id).unwrap_or(codemap::DUMMY_SP);
3471             self.session.span_bug(span,
3472                                   &format!("path resolved multiple times ({:?} before, {:?} now)",
3473                                            prev_res,
3474                                            resolution));
3475         }
3476     }
3477
3478     fn enforce_default_binding_mode(&mut self,
3479                                     pat: &Pat,
3480                                     pat_binding_mode: BindingMode,
3481                                     descr: &str) {
3482         match pat_binding_mode {
3483             BindByValue(_) => {}
3484             BindByRef(..) => {
3485                 resolve_error(self,
3486                               pat.span,
3487                               ResolutionError::CannotUseRefBindingModeWith(descr));
3488             }
3489         }
3490     }
3491 }
3492
3493
3494 fn names_to_string(names: &[Name]) -> String {
3495     let mut first = true;
3496     let mut result = String::new();
3497     for name in names {
3498         if first {
3499             first = false
3500         } else {
3501             result.push_str("::")
3502         }
3503         result.push_str(&name.as_str());
3504     }
3505     result
3506 }
3507
3508 fn path_names_to_string(path: &Path, depth: usize) -> String {
3509     let names: Vec<ast::Name> = path.segments[..path.segments.len() - depth]
3510                                     .iter()
3511                                     .map(|seg| seg.identifier.name)
3512                                     .collect();
3513     names_to_string(&names[..])
3514 }
3515
3516 /// A somewhat inefficient routine to obtain the name of a module.
3517 fn module_to_string<'a>(module: Module<'a>) -> String {
3518     let mut names = Vec::new();
3519
3520     fn collect_mod<'a>(names: &mut Vec<ast::Name>, module: Module<'a>) {
3521         match module.parent_link {
3522             NoParentLink => {}
3523             ModuleParentLink(ref module, name) => {
3524                 names.push(name);
3525                 collect_mod(names, module);
3526             }
3527             BlockParentLink(ref module, _) => {
3528                 // danger, shouldn't be ident?
3529                 names.push(special_idents::opaque.name);
3530                 collect_mod(names, module);
3531             }
3532         }
3533     }
3534     collect_mod(&mut names, module);
3535
3536     if names.is_empty() {
3537         return "???".to_string();
3538     }
3539     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
3540 }
3541
3542 fn err_path_resolution() -> PathResolution {
3543     PathResolution {
3544         base_def: Def::Err,
3545         last_private: LastMod(AllPublic),
3546         depth: 0,
3547     }
3548 }
3549
3550
3551 pub struct CrateMap {
3552     pub def_map: RefCell<DefMap>,
3553     pub freevars: FreevarMap,
3554     pub export_map: ExportMap,
3555     pub trait_map: TraitMap,
3556     pub external_exports: ExternalExports,
3557     pub glob_map: Option<GlobMap>,
3558 }
3559
3560 #[derive(PartialEq,Copy, Clone)]
3561 pub enum MakeGlobMap {
3562     Yes,
3563     No,
3564 }
3565
3566 /// Entry point to crate resolution.
3567 pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
3568                                ast_map: &'a hir_map::Map<'tcx>,
3569                                make_glob_map: MakeGlobMap)
3570                                -> CrateMap {
3571     // Currently, we ignore the name resolution data structures for
3572     // the purposes of dependency tracking. Instead we will run name
3573     // resolution and include its output in the hash of each item,
3574     // much like we do for macro expansion. In other words, the hash
3575     // reflects not just its contents but the results of name
3576     // resolution on those contents. Hopefully we'll push this back at
3577     // some point.
3578     let _task = ast_map.dep_graph.in_task(DepNode::Resolve);
3579
3580     let krate = ast_map.krate();
3581     let arenas = Resolver::arenas();
3582     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, &arenas, None);
3583
3584     resolver.resolve_crate(krate);
3585
3586     check_unused::check_crate(&mut resolver, krate);
3587
3588     CrateMap {
3589         def_map: resolver.def_map,
3590         freevars: resolver.freevars,
3591         export_map: resolver.export_map,
3592         trait_map: resolver.trait_map,
3593         external_exports: resolver.external_exports,
3594         glob_map: if resolver.make_glob_map {
3595             Some(resolver.glob_map)
3596         } else {
3597             None
3598         },
3599     }
3600 }
3601
3602 /// Builds a name resolution walker to be used within this module,
3603 /// or used externally, with an optional callback function.
3604 ///
3605 /// The callback takes a &mut bool which allows callbacks to end a
3606 /// walk when set to true, passing through the rest of the walk, while
3607 /// preserving the ribs + current module. This allows resolve_path
3608 /// calls to be made with the correct scope info. The node in the
3609 /// callback corresponds to the current node in the walk.
3610 pub fn create_resolver<'a, 'tcx>(session: &'a Session,
3611                                  ast_map: &'a hir_map::Map<'tcx>,
3612                                  krate: &'a Crate,
3613                                  make_glob_map: MakeGlobMap,
3614                                  arenas: &'a ResolverArenas<'a>,
3615                                  callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>)
3616                                  -> Resolver<'a, 'tcx> {
3617     let mut resolver = Resolver::new(session, ast_map, make_glob_map, arenas);
3618
3619     resolver.callback = callback;
3620
3621     build_reduced_graph::build_reduced_graph(&mut resolver, krate);
3622
3623     resolve_imports::resolve_imports(&mut resolver);
3624
3625     resolver
3626 }
3627
3628 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }