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(rustc_diagnostic_macros)]
  22 #![feature(rustc_private)]
  23 #![feature(staged_api)]
  24
  25 #[macro_use]
  26 extern crate log;
  27 #[macro_use]
  28 extern crate syntax;
  29 extern crate arena;
  30 #[macro_use]
  31 #[no_link]
  32 extern crate rustc_bitflags;
  33 extern crate rustc_front;
  34 extern crate rustc;
  35
  36 use self::PatternBindingMode::*;
  37 use self::Namespace::*;
  38 use self::ResolveResult::*;
  39 use self::FallbackSuggestion::*;
  40 use self::TypeParameters::*;
  41 use self::RibKind::*;
  42 use self::UseLexicalScopeFlag::*;
  43 use self::ModulePrefixResult::*;
  44 use self::AssocItemResolveResult::*;
  45 use self::BareIdentifierPatternResolution::*;
  46 use self::ParentLink::*;
  47 use self::FallbackChecks::*;
  48
  49 use rustc::dep_graph::DepNode;
  50 use rustc::front::map as hir_map;
  51 use rustc::session::Session;
  52 use rustc::lint;
  53 use rustc::middle::cstore::{CrateStore, DefLike, DlDef};
  54 use rustc::middle::def::*;
  55 use rustc::middle::def_id::DefId;
  56 use rustc::middle::pat_util::pat_bindings;
  57 use rustc::middle::privacy::*;
  58 use rustc::middle::subst::{ParamSpace, FnSpace, TypeSpace};
  59 use rustc::middle::ty::{Freevar, FreevarMap, TraitMap, GlobMap};
  60 use rustc::util::nodemap::{NodeMap, DefIdSet, FnvHashMap};
  61
  62 use syntax::ast::{self, FloatTy};
  63 use syntax::ast::{CRATE_NODE_ID, Name, NodeId, CrateNum, IntTy, UintTy};
  64 use syntax::attr::AttrMetaMethods;
  65 use syntax::codemap::{self, Span, Pos};
  66 use syntax::errors::DiagnosticBuilder;
  67 use syntax::parse::token::{self, special_names, special_idents};
  68 use syntax::util::lev_distance::find_best_match_for_name;
  69
  70 use rustc_front::intravisit::{self, FnKind, Visitor};
  71 use rustc_front::hir;
  72 use rustc_front::hir::{Arm, BindByRef, BindByValue, BindingMode, Block};
  73 use rustc_front::hir::Crate;
  74 use rustc_front::hir::{Expr, ExprAgain, ExprBreak, ExprCall, ExprField};
  75 use rustc_front::hir::{ExprLoop, ExprWhile, ExprMethodCall};
  76 use rustc_front::hir::{ExprPath, ExprStruct, FnDecl};
  77 use rustc_front::hir::{ForeignItemFn, ForeignItemStatic, Generics};
  78 use rustc_front::hir::{ImplItem, Item, ItemConst, ItemEnum, ItemExternCrate};
  79 use rustc_front::hir::{ItemFn, ItemForeignMod, ItemImpl, ItemMod, ItemStatic, ItemDefaultImpl};
  80 use rustc_front::hir::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  81 use rustc_front::hir::Local;
  82 use rustc_front::hir::{Pat, PatKind, Path, PrimTy};
  83 use rustc_front::hir::{PathSegment, PathParameters};
  84 use rustc_front::hir::HirVec;
  85 use rustc_front::hir::{TraitRef, Ty, TyBool, TyChar, TyFloat, TyInt};
  86 use rustc_front::hir::{TyRptr, TyStr, TyUint, TyPath, TyPtr};
  87 use rustc_front::util::walk_pat;
  88
  89 use std::collections::{HashMap, HashSet};
  90 use std::cell::{Cell, RefCell};
  91 use std::fmt;
  92 use std::mem::replace;
  93
  94 use resolve_imports::{ImportDirective, NameResolution};
  95
  96 // NB: This module needs to be declared first so diagnostics are
  97 // registered before they are used.
  98 pub mod diagnostics;
  99
 100 mod check_unused;
 101 mod build_reduced_graph;
 102 mod resolve_imports;
 103
 104 // Perform the callback, not walking deeper if the return is true
 105 macro_rules! execute_callback {
 106     ($node: expr, $walker: expr) => (
 107         if let Some(ref callback) = $walker.callback {
 108             if callback($node, &mut $walker.resolved) {
 109                 return;
 110             }
 111         }
 112     )
 113 }
 114
 115 enum SuggestionType {
 116     Macro(String),
 117     Function(token::InternedString),
 118     NotFound,
 119 }
 120
 121 /// Candidates for a name resolution failure
 122 pub struct SuggestedCandidates {
 123     name: String,
 124     candidates: Vec<Path>,
 125 }
 126
 127 pub enum ResolutionError<'a> {
 128     /// error E0401: can't use type parameters from outer function
 129     TypeParametersFromOuterFunction,
 130     /// error E0402: cannot use an outer type parameter in this context
 131     OuterTypeParameterContext,
 132     /// error E0403: the name is already used for a type parameter in this type parameter list
 133     NameAlreadyUsedInTypeParameterList(Name),
 134     /// error E0404: is not a trait
 135     IsNotATrait(&'a str),
 136     /// error E0405: use of undeclared trait name
 137     UndeclaredTraitName(&'a str, SuggestedCandidates),
 138     /// error E0406: undeclared associated type
 139     UndeclaredAssociatedType,
 140     /// error E0407: method is not a member of trait
 141     MethodNotMemberOfTrait(Name, &'a str),
 142     /// error E0437: type is not a member of trait
 143     TypeNotMemberOfTrait(Name, &'a str),
 144     /// error E0438: const is not a member of trait
 145     ConstNotMemberOfTrait(Name, &'a str),
 146     /// error E0408: variable `{}` from pattern #1 is not bound in pattern
 147     VariableNotBoundInPattern(Name, usize),
 148     /// error E0409: variable is bound with different mode in pattern #{} than in pattern #1
 149     VariableBoundWithDifferentMode(Name, usize),
 150     /// error E0410: variable from pattern is not bound in pattern #1
 151     VariableNotBoundInParentPattern(Name, usize),
 152     /// error E0411: use of `Self` outside of an impl or trait
 153     SelfUsedOutsideImplOrTrait,
 154     /// error E0412: use of undeclared
 155     UseOfUndeclared(&'a str, &'a str, SuggestedCandidates),
 156     /// error E0413: declaration shadows an enum variant or unit-like struct in scope
 157     DeclarationShadowsEnumVariantOrUnitLikeStruct(Name),
 158     /// error E0414: only irrefutable patterns allowed here
 159     OnlyIrrefutablePatternsAllowedHere(DefId, Name),
 160     /// error E0415: identifier is bound more than once in this parameter list
 161     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 162     /// error E0416: identifier is bound more than once in the same pattern
 163     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 164     /// error E0417: static variables cannot be referenced in a pattern
 165     StaticVariableReference,
 166     /// error E0418: is not an enum variant, struct or const
 167     NotAnEnumVariantStructOrConst(&'a str),
 168     /// error E0419: unresolved enum variant, struct or const
 169     UnresolvedEnumVariantStructOrConst(&'a str),
 170     /// error E0420: is not an associated const
 171     NotAnAssociatedConst(&'a str),
 172     /// error E0421: unresolved associated const
 173     UnresolvedAssociatedConst(&'a str),
 174     /// error E0422: does not name a struct
 175     DoesNotNameAStruct(&'a str),
 176     /// error E0423: is a struct variant name, but this expression uses it like a function name
 177     StructVariantUsedAsFunction(&'a str),
 178     /// error E0424: `self` is not available in a static method
 179     SelfNotAvailableInStaticMethod,
 180     /// error E0425: unresolved name
 181     UnresolvedName(&'a str, &'a str, UnresolvedNameContext),
 182     /// error E0426: use of undeclared label
 183     UndeclaredLabel(&'a str),
 184     /// error E0427: cannot use `ref` binding mode with ...
 185     CannotUseRefBindingModeWith(&'a str),
 186     /// error E0428: duplicate definition
 187     DuplicateDefinition(&'a str, Name),
 188     /// error E0429: `self` imports are only allowed within a { } list
 189     SelfImportsOnlyAllowedWithin,
 190     /// error E0430: `self` import can only appear once in the list
 191     SelfImportCanOnlyAppearOnceInTheList,
 192     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 193     SelfImportOnlyInImportListWithNonEmptyPrefix,
 194     /// error E0432: unresolved import
 195     UnresolvedImport(Option<(&'a str, &'a str)>),
 196     /// error E0433: failed to resolve
 197     FailedToResolve(&'a str),
 198     /// error E0434: can't capture dynamic environment in a fn item
 199     CannotCaptureDynamicEnvironmentInFnItem,
 200     /// error E0435: attempt to use a non-constant value in a constant
 201     AttemptToUseNonConstantValueInConstant,
 202 }
 203
 204 /// Context of where `ResolutionError::UnresolvedName` arose.
 205 #[derive(Clone, PartialEq, Eq, Debug)]
 206 pub enum UnresolvedNameContext {
 207     /// `PathIsMod(id)` indicates that a given path, used in
 208     /// expression context, actually resolved to a module rather than
 209     /// a value. The `id` attached to the variant is the node id of
 210     /// the erroneous path expression.
 211     PathIsMod(ast::NodeId),
 212
 213     /// `Other` means we have no extra information about the context
 214     /// of the unresolved name error. (Maybe we could eliminate all
 215     /// such cases; but for now, this is an information-free default.)
 216     Other,
 217 }
 218
 219 fn resolve_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 220                                        span: syntax::codemap::Span,
 221                                        resolution_error: ResolutionError<'b>) {
 222     resolve_struct_error(resolver, span, resolution_error).emit();
 223 }
 224
 225 fn resolve_struct_error<'b, 'a: 'b, 'tcx: 'a>(resolver: &'b Resolver<'a, 'tcx>,
 226                                               span: syntax::codemap::Span,
 227                                               resolution_error: ResolutionError<'b>)
 228                                               -> DiagnosticBuilder<'a> {
 229     if !resolver.emit_errors {
 230         return resolver.session.diagnostic().struct_dummy();
 231     }
 232
 233     match resolution_error {
 234         ResolutionError::TypeParametersFromOuterFunction => {
 235             struct_span_err!(resolver.session,
 236                              span,
 237                              E0401,
 238                              "can't use type parameters from outer function; try using a local \
 239                               type parameter instead")
 240         }
 241         ResolutionError::OuterTypeParameterContext => {
 242             struct_span_err!(resolver.session,
 243                              span,
 244                              E0402,
 245                              "cannot use an outer type parameter in this context")
 246         }
 247         ResolutionError::NameAlreadyUsedInTypeParameterList(name) => {
 248             struct_span_err!(resolver.session,
 249                              span,
 250                              E0403,
 251                              "the name `{}` is already used for a type parameter in this type \
 252                               parameter list",
 253                              name)
 254         }
 255         ResolutionError::IsNotATrait(name) => {
 256             struct_span_err!(resolver.session, span, E0404, "`{}` is not a trait", name)
 257         }
 258         ResolutionError::UndeclaredTraitName(name, candidates) => {
 259             let mut err = struct_span_err!(resolver.session,
 260                                            span,
 261                                            E0405,
 262                                            "trait `{}` is not in scope",
 263                                            name);
 264             show_candidates(&mut err, span, &candidates);
 265             err
 266         }
 267         ResolutionError::UndeclaredAssociatedType => {
 268             struct_span_err!(resolver.session, span, E0406, "undeclared associated type")
 269         }
 270         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 271             struct_span_err!(resolver.session,
 272                              span,
 273                              E0407,
 274                              "method `{}` is not a member of trait `{}`",
 275                              method,
 276                              trait_)
 277         }
 278         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 279             struct_span_err!(resolver.session,
 280                              span,
 281                              E0437,
 282                              "type `{}` is not a member of trait `{}`",
 283                              type_,
 284                              trait_)
 285         }
 286         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 287             struct_span_err!(resolver.session,
 288                              span,
 289                              E0438,
 290                              "const `{}` is not a member of trait `{}`",
 291                              const_,
 292                              trait_)
 293         }
 294         ResolutionError::VariableNotBoundInPattern(variable_name, pattern_number) => {
 295             struct_span_err!(resolver.session,
 296                              span,
 297                              E0408,
 298                              "variable `{}` from pattern #1 is not bound in pattern #{}",
 299                              variable_name,
 300                              pattern_number)
 301         }
 302         ResolutionError::VariableBoundWithDifferentMode(variable_name, pattern_number) => {
 303             struct_span_err!(resolver.session,
 304                              span,
 305                              E0409,
 306                              "variable `{}` is bound with different mode in pattern #{} than in \
 307                               pattern #1",
 308                              variable_name,
 309                              pattern_number)
 310         }
 311         ResolutionError::VariableNotBoundInParentPattern(variable_name, pattern_number) => {
 312             struct_span_err!(resolver.session,
 313                              span,
 314                              E0410,
 315                              "variable `{}` from pattern #{} is not bound in pattern #1",
 316                              variable_name,
 317                              pattern_number)
 318         }
 319         ResolutionError::SelfUsedOutsideImplOrTrait => {
 320             struct_span_err!(resolver.session,
 321                              span,
 322                              E0411,
 323                              "use of `Self` outside of an impl or trait")
 324         }
 325         ResolutionError::UseOfUndeclared(kind, name, candidates) => {
 326             let mut err = struct_span_err!(resolver.session,
 327                                            span,
 328                                            E0412,
 329                                            "{} `{}` is undefined or not in scope",
 330                                            kind,
 331                                            name);
 332             show_candidates(&mut err, span, &candidates);
 333             err
 334         }
 335         ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(name) => {
 336             struct_span_err!(resolver.session,
 337                              span,
 338                              E0413,
 339                              "declaration of `{}` shadows an enum variant \
 340                               or unit-like struct in scope",
 341                              name)
 342         }
 343         ResolutionError::OnlyIrrefutablePatternsAllowedHere(did, name) => {
 344             let mut err = struct_span_err!(resolver.session,
 345                                            span,
 346                                            E0414,
 347                                            "only irrefutable patterns allowed here");
 348             err.span_note(span,
 349                           "there already is a constant in scope sharing the same \
 350                            name as this pattern");
 351             if let Some(sp) = resolver.ast_map.span_if_local(did) {
 352                 err.span_note(sp, "constant defined here");
 353             }
 354             if let Success(binding) = resolver.current_module.resolve_name(name, ValueNS, true) {
 355                 if binding.is_import() {
 356                     err.span_note(binding.span.unwrap(), "constant imported here");
 357                 }
 358             }
 359             err
 360         }
 361         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 362             struct_span_err!(resolver.session,
 363                              span,
 364                              E0415,
 365                              "identifier `{}` is bound more than once in this parameter list",
 366                              identifier)
 367         }
 368         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 369             struct_span_err!(resolver.session,
 370                              span,
 371                              E0416,
 372                              "identifier `{}` is bound more than once in the same pattern",
 373                              identifier)
 374         }
 375         ResolutionError::StaticVariableReference => {
 376             struct_span_err!(resolver.session,
 377                              span,
 378                              E0417,
 379                              "static variables cannot be referenced in a pattern, use a \
 380                               `const` instead")
 381         }
 382         ResolutionError::NotAnEnumVariantStructOrConst(name) => {
 383             struct_span_err!(resolver.session,
 384                              span,
 385                              E0418,
 386                              "`{}` is not an enum variant, struct or const",
 387                              name)
 388         }
 389         ResolutionError::UnresolvedEnumVariantStructOrConst(name) => {
 390             struct_span_err!(resolver.session,
 391                              span,
 392                              E0419,
 393                              "unresolved enum variant, struct or const `{}`",
 394                              name)
 395         }
 396         ResolutionError::NotAnAssociatedConst(name) => {
 397             struct_span_err!(resolver.session,
 398                              span,
 399                              E0420,
 400                              "`{}` is not an associated const",
 401                              name)
 402         }
 403         ResolutionError::UnresolvedAssociatedConst(name) => {
 404             struct_span_err!(resolver.session,
 405                              span,
 406                              E0421,
 407                              "unresolved associated const `{}`",
 408                              name)
 409         }
 410         ResolutionError::DoesNotNameAStruct(name) => {
 411             struct_span_err!(resolver.session,
 412                              span,
 413                              E0422,
 414                              "`{}` does not name a structure",
 415                              name)
 416         }
 417         ResolutionError::StructVariantUsedAsFunction(path_name) => {
 418             struct_span_err!(resolver.session,
 419                              span,
 420                              E0423,
 421                              "`{}` is the name of a struct or struct variant, but this expression \
 422                              uses it like a function name",
 423                              path_name)
 424         }
 425         ResolutionError::SelfNotAvailableInStaticMethod => {
 426             struct_span_err!(resolver.session,
 427                              span,
 428                              E0424,
 429                              "`self` is not available in a static method. Maybe a `self` \
 430                              argument is missing?")
 431         }
 432         ResolutionError::UnresolvedName(path, msg, context) => {
 433             let mut err = struct_span_err!(resolver.session,
 434                                            span,
 435                                            E0425,
 436                                            "unresolved name `{}`{}",
 437                                            path,
 438                                            msg);
 439
 440             match context {
 441                 UnresolvedNameContext::Other => { } // no help available
 442                 UnresolvedNameContext::PathIsMod(id) => {
 443                     let mut help_msg = String::new();
 444                     let parent_id = resolver.ast_map.get_parent_node(id);
 445                     if let Some(hir_map::Node::NodeExpr(e)) = resolver.ast_map.find(parent_id) {
 446                         match e.node {
 447                             ExprField(_, ident) => {
 448                                 help_msg = format!("To reference an item from the \
 449                                                     `{module}` module, use \
 450                                                     `{module}::{ident}`",
 451                                                    module = path,
 452                                                    ident = ident.node);
 453                             }
 454                             ExprMethodCall(ident, _, _) => {
 455                                 help_msg = format!("To call a function from the \
 456                                                     `{module}` module, use \
 457                                                     `{module}::{ident}(..)`",
 458                                                    module = path,
 459                                                    ident = ident.node);
 460                             }
 461                             ExprCall(_, _) => {
 462                                 help_msg = format!("No function corresponds to `{module}(..)`",
 463                                                    module = path);
 464                             }
 465                             _ => { } // no help available
 466                         }
 467                     } else {
 468                         help_msg = format!("Module `{module}` cannot be the value of an expression",
 469                                            module = path);
 470                     }
 471
 472                     if !help_msg.is_empty() {
 473                         err.fileline_help(span, &help_msg);
 474                     }
 475                 }
 476             }
 477             err
 478         }
 479         ResolutionError::UndeclaredLabel(name) => {
 480             struct_span_err!(resolver.session,
 481                              span,
 482                              E0426,
 483                              "use of undeclared label `{}`",
 484                              name)
 485         }
 486         ResolutionError::CannotUseRefBindingModeWith(descr) => {
 487             struct_span_err!(resolver.session,
 488                              span,
 489                              E0427,
 490                              "cannot use `ref` binding mode with {}",
 491                              descr)
 492         }
 493         ResolutionError::DuplicateDefinition(namespace, name) => {
 494             struct_span_err!(resolver.session,
 495                              span,
 496                              E0428,
 497                              "duplicate definition of {} `{}`",
 498                              namespace,
 499                              name)
 500         }
 501         ResolutionError::SelfImportsOnlyAllowedWithin => {
 502             struct_span_err!(resolver.session,
 503                              span,
 504                              E0429,
 505                              "{}",
 506                              "`self` imports are only allowed within a { } list")
 507         }
 508         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 509             struct_span_err!(resolver.session,
 510                              span,
 511                              E0430,
 512                              "`self` import can only appear once in the list")
 513         }
 514         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 515             struct_span_err!(resolver.session,
 516                              span,
 517                              E0431,
 518                              "`self` import can only appear in an import list with a \
 519                               non-empty prefix")
 520         }
 521         ResolutionError::UnresolvedImport(name) => {
 522             let msg = match name {
 523                 Some((n, p)) => format!("unresolved import `{}`{}", n, p),
 524                 None => "unresolved import".to_owned(),
 525             };
 526             struct_span_err!(resolver.session, span, E0432, "{}", msg)
 527         }
 528         ResolutionError::FailedToResolve(msg) => {
 529             struct_span_err!(resolver.session, span, E0433, "failed to resolve. {}", msg)
 530         }
 531         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 532             struct_span_err!(resolver.session,
 533                              span,
 534                              E0434,
 535                              "{}",
 536                              "can't capture dynamic environment in a fn item; use the || { ... } \
 537                               closure form instead")
 538         }
 539         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 540             struct_span_err!(resolver.session,
 541                              span,
 542                              E0435,
 543                              "attempt to use a non-constant value in a constant")
 544         }
 545     }
 546 }
 547
 548 #[derive(Copy, Clone)]
 549 struct BindingInfo {
 550     span: Span,
 551     binding_mode: BindingMode,
 552 }
 553
 554 // Map from the name in a pattern to its binding mode.
 555 type BindingMap = HashMap<Name, BindingInfo>;
 556
 557 #[derive(Copy, Clone, PartialEq)]
 558 enum PatternBindingMode {
 559     RefutableMode,
 560     LocalIrrefutableMode,
 561     ArgumentIrrefutableMode,
 562 }
 563
 564 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 565 pub enum Namespace {
 566     TypeNS,
 567     ValueNS,
 568 }
 569
 570 impl<'a, 'v, 'tcx> Visitor<'v> for Resolver<'a, 'tcx> {
 571     fn visit_nested_item(&mut self, item: hir::ItemId) {
 572         self.visit_item(self.ast_map.expect_item(item.id))
 573     }
 574     fn visit_item(&mut self, item: &Item) {
 575         execute_callback!(hir_map::Node::NodeItem(item), self);
 576         self.resolve_item(item);
 577     }
 578     fn visit_arm(&mut self, arm: &Arm) {
 579         self.resolve_arm(arm);
 580     }
 581     fn visit_block(&mut self, block: &Block) {
 582         execute_callback!(hir_map::Node::NodeBlock(block), self);
 583         self.resolve_block(block);
 584     }
 585     fn visit_expr(&mut self, expr: &Expr) {
 586         execute_callback!(hir_map::Node::NodeExpr(expr), self);
 587         self.resolve_expr(expr);
 588     }
 589     fn visit_local(&mut self, local: &Local) {
 590         execute_callback!(hir_map::Node::NodeLocal(&local.pat), self);
 591         self.resolve_local(local);
 592     }
 593     fn visit_ty(&mut self, ty: &Ty) {
 594         self.resolve_type(ty);
 595     }
 596     fn visit_generics(&mut self, generics: &Generics) {
 597         self.resolve_generics(generics);
 598     }
 599     fn visit_poly_trait_ref(&mut self, tref: &hir::PolyTraitRef, m: &hir::TraitBoundModifier) {
 600         match self.resolve_trait_reference(tref.trait_ref.ref_id, &tref.trait_ref.path, 0) {
 601             Ok(def) => self.record_def(tref.trait_ref.ref_id, def),
 602             Err(_) => {
 603                 // error already reported
 604                 self.record_def(tref.trait_ref.ref_id, err_path_resolution())
 605             }
 606         }
 607         intravisit::walk_poly_trait_ref(self, tref, m);
 608     }
 609     fn visit_variant(&mut self,
 610                      variant: &hir::Variant,
 611                      generics: &Generics,
 612                      item_id: ast::NodeId) {
 613         execute_callback!(hir_map::Node::NodeVariant(variant), self);
 614         if let Some(ref dis_expr) = variant.node.disr_expr {
 615             // resolve the discriminator expr as a constant
 616             self.with_constant_rib(|this| {
 617                 this.visit_expr(dis_expr);
 618             });
 619         }
 620
 621         // `intravisit::walk_variant` without the discriminant expression.
 622         self.visit_variant_data(&variant.node.data,
 623                                 variant.node.name,
 624                                 generics,
 625                                 item_id,
 626                                 variant.span);
 627     }
 628     fn visit_foreign_item(&mut self, foreign_item: &hir::ForeignItem) {
 629         execute_callback!(hir_map::Node::NodeForeignItem(foreign_item), self);
 630         let type_parameters = match foreign_item.node {
 631             ForeignItemFn(_, ref generics) => {
 632                 HasTypeParameters(generics, FnSpace, ItemRibKind)
 633             }
 634             ForeignItemStatic(..) => NoTypeParameters,
 635         };
 636         self.with_type_parameter_rib(type_parameters, |this| {
 637             intravisit::walk_foreign_item(this, foreign_item);
 638         });
 639     }
 640     fn visit_fn(&mut self,
 641                 function_kind: FnKind<'v>,
 642                 declaration: &'v FnDecl,
 643                 block: &'v Block,
 644                 _: Span,
 645                 node_id: NodeId) {
 646         let rib_kind = match function_kind {
 647             FnKind::ItemFn(_, generics, _, _, _, _) => {
 648                 self.visit_generics(generics);
 649                 ItemRibKind
 650             }
 651             FnKind::Method(_, sig, _) => {
 652                 self.visit_generics(&sig.generics);
 653                 self.visit_explicit_self(&sig.explicit_self);
 654                 MethodRibKind
 655             }
 656             FnKind::Closure => ClosureRibKind(node_id),
 657         };
 658         self.resolve_function(rib_kind, declaration, block);
 659     }
 660 }
 661
 662 pub type ErrorMessage = Option<(Span, String)>;
 663
 664 #[derive(Clone, PartialEq, Eq)]
 665 pub enum ResolveResult<T> {
 666     Failed(ErrorMessage), // Failed to resolve the name, optional helpful error message.
 667     Indeterminate, // Couldn't determine due to unresolved globs.
 668     Success(T), // Successfully resolved the import.
 669 }
 670
 671 impl<T> ResolveResult<T> {
 672     fn and_then<U, F: FnOnce(T) -> ResolveResult<U>>(self, f: F) -> ResolveResult<U> {
 673         match self {
 674             Failed(msg) => Failed(msg),
 675             Indeterminate => Indeterminate,
 676             Success(t) => f(t),
 677         }
 678     }
 679
 680     fn success(self) -> Option<T> {
 681         match self {
 682             Success(t) => Some(t),
 683             _ => None,
 684         }
 685     }
 686 }
 687
 688 enum FallbackSuggestion {
 689     NoSuggestion,
 690     Field,
 691     Method,
 692     TraitItem,
 693     StaticMethod(String),
 694     TraitMethod(String),
 695 }
 696
 697 #[derive(Copy, Clone)]
 698 enum TypeParameters<'tcx, 'a> {
 699     NoTypeParameters,
 700     HasTypeParameters(// Type parameters.
 701                       &'a Generics,
 702
 703                       // Identifies the things that these parameters
 704                       // were declared on (type, fn, etc)
 705                       ParamSpace,
 706
 707                       // The kind of the rib used for type parameters.
 708                       RibKind<'tcx>),
 709 }
 710
 711 // The rib kind controls the translation of local
 712 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 713 #[derive(Copy, Clone, Debug)]
 714 enum RibKind<'a> {
 715     // No translation needs to be applied.
 716     NormalRibKind,
 717
 718     // We passed through a closure scope at the given node ID.
 719     // Translate upvars as appropriate.
 720     ClosureRibKind(NodeId /* func id */),
 721
 722     // We passed through an impl or trait and are now in one of its
 723     // methods. Allow references to ty params that impl or trait
 724     // binds. Disallow any other upvars (including other ty params that are
 725     // upvars).
 726     MethodRibKind,
 727
 728     // We passed through an item scope. Disallow upvars.
 729     ItemRibKind,
 730
 731     // We're in a constant item. Can't refer to dynamic stuff.
 732     ConstantItemRibKind,
 733
 734     // We passed through an anonymous module.
 735     AnonymousModuleRibKind(Module<'a>),
 736 }
 737
 738 #[derive(Copy, Clone)]
 739 enum UseLexicalScopeFlag {
 740     DontUseLexicalScope,
 741     UseLexicalScope,
 742 }
 743
 744 enum ModulePrefixResult<'a> {
 745     NoPrefixFound,
 746     PrefixFound(Module<'a>, usize),
 747 }
 748
 749 #[derive(Copy, Clone)]
 750 enum AssocItemResolveResult {
 751     /// Syntax such as `<T>::item`, which can't be resolved until type
 752     /// checking.
 753     TypecheckRequired,
 754     /// We should have been able to resolve the associated item.
 755     ResolveAttempt(Option<PathResolution>),
 756 }
 757
 758 #[derive(Copy, Clone)]
 759 enum BareIdentifierPatternResolution {
 760     FoundStructOrEnumVariant(Def, LastPrivate),
 761     FoundConst(Def, LastPrivate, Name),
 762     BareIdentifierPatternUnresolved,
 763 }
 764
 765 /// One local scope.
 766 #[derive(Debug)]
 767 struct Rib<'a> {
 768     bindings: HashMap<Name, DefLike>,
 769     kind: RibKind<'a>,
 770 }
 771
 772 impl<'a> Rib<'a> {
 773     fn new(kind: RibKind<'a>) -> Rib<'a> {
 774         Rib {
 775             bindings: HashMap::new(),
 776             kind: kind,
 777         }
 778     }
 779 }
 780
 781 /// A definition along with the index of the rib it was found on
 782 struct LocalDef {
 783     ribs: Option<(Namespace, usize)>,
 784     def: Def,
 785 }
 786
 787 impl LocalDef {
 788     fn from_def(def: Def) -> Self {
 789         LocalDef {
 790             ribs: None,
 791             def: def,
 792         }
 793     }
 794 }
 795
 796 /// The link from a module up to its nearest parent node.
 797 #[derive(Clone,Debug)]
 798 enum ParentLink<'a> {
 799     NoParentLink,
 800     ModuleParentLink(Module<'a>, Name),
 801     BlockParentLink(Module<'a>, NodeId),
 802 }
 803
 804 /// One node in the tree of modules.
 805 pub struct ModuleS<'a> {
 806     parent_link: ParentLink<'a>,
 807     def: Option<Def>,
 808     is_public: bool,
 809     is_extern_crate: bool,
 810
 811     resolutions: RefCell<HashMap<(Name, Namespace), NameResolution<'a>>>,
 812     unresolved_imports: RefCell<Vec<ImportDirective>>,
 813
 814     // The module children of this node, including normal modules and anonymous modules.
 815     // Anonymous children are pseudo-modules that are implicitly created around items
 816     // contained within blocks.
 817     //
 818     // For example, if we have this:
 819     //
 820     //  fn f() {
 821     //      fn g() {
 822     //          ...
 823     //      }
 824     //  }
 825     //
 826     // There will be an anonymous module created around `g` with the ID of the
 827     // entry block for `f`.
 828     module_children: RefCell<NodeMap<Module<'a>>>,
 829
 830     shadowed_traits: RefCell<Vec<&'a NameBinding<'a>>>,
 831
 832     // The number of unresolved globs that this module exports.
 833     glob_count: Cell<usize>,
 834
 835     // The number of unresolved pub imports (both regular and globs) in this module
 836     pub_count: Cell<usize>,
 837
 838     // The number of unresolved pub glob imports in this module
 839     pub_glob_count: Cell<usize>,
 840
 841     // Whether this module is populated. If not populated, any attempt to
 842     // access the children must be preceded with a
 843     // `populate_module_if_necessary` call.
 844     populated: Cell<bool>,
 845 }
 846
 847 pub type Module<'a> = &'a ModuleS<'a>;
 848
 849 impl<'a> ModuleS<'a> {
 850
 851     fn new(parent_link: ParentLink<'a>, def: Option<Def>, external: bool, is_public: bool) -> Self {
 852         ModuleS {
 853             parent_link: parent_link,
 854             def: def,
 855             is_public: is_public,
 856             is_extern_crate: false,
 857             resolutions: RefCell::new(HashMap::new()),
 858             unresolved_imports: RefCell::new(Vec::new()),
 859             module_children: RefCell::new(NodeMap()),
 860             shadowed_traits: RefCell::new(Vec::new()),
 861             glob_count: Cell::new(0),
 862             pub_count: Cell::new(0),
 863             pub_glob_count: Cell::new(0),
 864             populated: Cell::new(!external),
 865         }
 866     }
 867
 868     fn resolve_name(&self, name: Name, ns: Namespace, allow_private_imports: bool)
 869                     -> ResolveResult<&'a NameBinding<'a>> {
 870         let glob_count =
 871             if allow_private_imports { self.glob_count.get() } else { self.pub_glob_count.get() };
 872
 873         self.resolutions.borrow().get(&(name, ns)).cloned().unwrap_or_default().result(glob_count)
 874             .and_then(|binding| {
 875                 let allowed = allow_private_imports || !binding.is_import() || binding.is_public();
 876                 if allowed { Success(binding) } else { Failed(None) }
 877             })
 878     }
 879
 880     // Define the name or return the existing binding if there is a collision.
 881     fn try_define_child(&self, name: Name, ns: Namespace, binding: &'a NameBinding<'a>)
 882                         -> Result<(), &'a NameBinding<'a>> {
 883         let mut children = self.resolutions.borrow_mut();
 884         let resolution = children.entry((name, ns)).or_insert_with(Default::default);
 885
 886         // FIXME #31379: We can use methods from imported traits shadowed by non-import items
 887         if let Some(old_binding) = resolution.binding {
 888             if !old_binding.is_import() && binding.is_import() {
 889                 if let Some(Def::Trait(_)) = binding.def() {
 890                     self.shadowed_traits.borrow_mut().push(binding);
 891                 }
 892             }
 893         }
 894
 895         resolution.try_define(binding)
 896     }
 897
 898     fn increment_outstanding_references_for(&self, name: Name, ns: Namespace) {
 899         let mut children = self.resolutions.borrow_mut();
 900         children.entry((name, ns)).or_insert_with(Default::default).outstanding_references += 1;
 901     }
 902
 903     fn decrement_outstanding_references_for(&self, name: Name, ns: Namespace) {
 904         match self.resolutions.borrow_mut().get_mut(&(name, ns)).unwrap().outstanding_references {
 905             0 => panic!("No more outstanding references!"),
 906             ref mut outstanding_references => { *outstanding_references -= 1; }
 907         }
 908     }
 909
 910     fn for_each_child<F: FnMut(Name, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 911         for (&(name, ns), name_resolution) in self.resolutions.borrow().iter() {
 912             name_resolution.binding.map(|binding| f(name, ns, binding));
 913         }
 914     }
 915
 916     fn def_id(&self) -> Option<DefId> {
 917         self.def.as_ref().map(Def::def_id)
 918     }
 919
 920     fn is_normal(&self) -> bool {
 921         match self.def {
 922             Some(Def::Mod(_)) | Some(Def::ForeignMod(_)) => true,
 923             _ => false,
 924         }
 925     }
 926
 927     fn is_trait(&self) -> bool {
 928         match self.def {
 929             Some(Def::Trait(_)) => true,
 930             _ => false,
 931         }
 932     }
 933
 934     pub fn inc_glob_count(&self) {
 935         self.glob_count.set(self.glob_count.get() + 1);
 936     }
 937     pub fn dec_glob_count(&self) {
 938         assert!(self.glob_count.get() > 0);
 939         self.glob_count.set(self.glob_count.get() - 1);
 940     }
 941     pub fn inc_pub_count(&self) {
 942         self.pub_count.set(self.pub_count.get() + 1);
 943     }
 944     pub fn dec_pub_count(&self) {
 945         assert!(self.pub_count.get() > 0);
 946         self.pub_count.set(self.pub_count.get() - 1);
 947     }
 948     pub fn inc_pub_glob_count(&self) {
 949         self.pub_glob_count.set(self.pub_glob_count.get() + 1);
 950     }
 951     pub fn dec_pub_glob_count(&self) {
 952         assert!(self.pub_glob_count.get() > 0);
 953         self.pub_glob_count.set(self.pub_glob_count.get() - 1);
 954     }
 955 }
 956
 957 impl<'a> fmt::Debug for ModuleS<'a> {
 958     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 959         write!(f,
 960                "{:?}, {}",
 961                self.def,
 962                if self.is_public {
 963                    "public"
 964                } else {
 965                    "private"
 966                })
 967     }
 968 }
 969
 970 bitflags! {
 971     #[derive(Debug)]
 972     flags DefModifiers: u8 {
 973         // Enum variants are always considered `PUBLIC`, this is needed for `use Enum::Variant`
 974         // or `use Enum::*` to work on private enums.
 975         const PUBLIC     = 1 << 0,
 976         const IMPORTABLE = 1 << 1,
 977         // Variants are considered `PUBLIC`, but some of them live in private enums.
 978         // We need to track them to prohibit reexports like `pub use PrivEnum::Variant`.
 979         const PRIVATE_VARIANT = 1 << 2,
 980         const PRELUDE = 1 << 3,
 981         const GLOB_IMPORTED = 1 << 4,
 982     }
 983 }
 984
 985 // Records a possibly-private value, type, or module definition.
 986 #[derive(Debug)]
 987 pub struct NameBinding<'a> {
 988     modifiers: DefModifiers,
 989     kind: NameBindingKind<'a>,
 990     span: Option<Span>,
 991 }
 992
 993 #[derive(Debug)]
 994 enum NameBindingKind<'a> {
 995     Def(Def),
 996     Module(Module<'a>),
 997     Import {
 998         binding: &'a NameBinding<'a>,
 999         id: NodeId,
1000     },
1001 }
1002
1003 impl<'a> NameBinding<'a> {
1004     fn create_from_module(module: Module<'a>, span: Option<Span>) -> Self {
1005         let modifiers = if module.is_public {
1006             DefModifiers::PUBLIC
1007         } else {
1008             DefModifiers::empty()
1009         } | DefModifiers::IMPORTABLE;
1010
1011         NameBinding { modifiers: modifiers, kind: NameBindingKind::Module(module), span: span }
1012     }
1013
1014     fn module(&self) -> Option<Module<'a>> {
1015         match self.kind {
1016             NameBindingKind::Module(module) => Some(module),
1017             NameBindingKind::Def(_) => None,
1018             NameBindingKind::Import { binding, .. } => binding.module(),
1019         }
1020     }
1021
1022     fn def(&self) -> Option<Def> {
1023         match self.kind {
1024             NameBindingKind::Def(def) => Some(def),
1025             NameBindingKind::Module(module) => module.def,
1026             NameBindingKind::Import { binding, .. } => binding.def(),
1027         }
1028     }
1029
1030     fn defined_with(&self, modifiers: DefModifiers) -> bool {
1031         self.modifiers.contains(modifiers)
1032     }
1033
1034     fn is_public(&self) -> bool {
1035         self.defined_with(DefModifiers::PUBLIC)
1036     }
1037
1038     fn def_and_lp(&self) -> (Def, LastPrivate) {
1039         let def = self.def().unwrap();
1040         if let Def::Err = def { return (def, LastMod(AllPublic)) }
1041         (def, LastMod(if self.is_public() { AllPublic } else { DependsOn(def.def_id()) }))
1042     }
1043
1044     fn is_extern_crate(&self) -> bool {
1045         self.module().map(|module| module.is_extern_crate).unwrap_or(false)
1046     }
1047
1048     fn is_import(&self) -> bool {
1049         match self.kind {
1050             NameBindingKind::Import { .. } => true,
1051             _ => false,
1052         }
1053     }
1054 }
1055
1056 /// Interns the names of the primitive types.
1057 struct PrimitiveTypeTable {
1058     primitive_types: HashMap<Name, PrimTy>,
1059 }
1060
1061 impl PrimitiveTypeTable {
1062     fn new() -> PrimitiveTypeTable {
1063         let mut table = PrimitiveTypeTable { primitive_types: HashMap::new() };
1064
1065         table.intern("bool", TyBool);
1066         table.intern("char", TyChar);
1067         table.intern("f32", TyFloat(FloatTy::F32));
1068         table.intern("f64", TyFloat(FloatTy::F64));
1069         table.intern("isize", TyInt(IntTy::Is));
1070         table.intern("i8", TyInt(IntTy::I8));
1071         table.intern("i16", TyInt(IntTy::I16));
1072         table.intern("i32", TyInt(IntTy::I32));
1073         table.intern("i64", TyInt(IntTy::I64));
1074         table.intern("str", TyStr);
1075         table.intern("usize", TyUint(UintTy::Us));
1076         table.intern("u8", TyUint(UintTy::U8));
1077         table.intern("u16", TyUint(UintTy::U16));
1078         table.intern("u32", TyUint(UintTy::U32));
1079         table.intern("u64", TyUint(UintTy::U64));
1080
1081         table
1082     }
1083
1084     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1085         self.primitive_types.insert(token::intern(string), primitive_type);
1086     }
1087 }
1088
1089 /// The main resolver class.
1090 pub struct Resolver<'a, 'tcx: 'a> {
1091     session: &'a Session,
1092
1093     ast_map: &'a hir_map::Map<'tcx>,
1094
1095     graph_root: Module<'a>,
1096
1097     trait_item_map: FnvHashMap<(Name, DefId), DefId>,
1098
1099     structs: FnvHashMap<DefId, Vec<Name>>,
1100
1101     // The number of imports that are currently unresolved.
1102     unresolved_imports: usize,
1103
1104     // The module that represents the current item scope.
1105     current_module: Module<'a>,
1106
1107     // The current set of local scopes, for values.
1108     // FIXME #4948: Reuse ribs to avoid allocation.
1109     value_ribs: Vec<Rib<'a>>,
1110
1111     // The current set of local scopes, for types.
1112     type_ribs: Vec<Rib<'a>>,
1113
1114     // The current set of local scopes, for labels.
1115     label_ribs: Vec<Rib<'a>>,
1116
1117     // The trait that the current context can refer to.
1118     current_trait_ref: Option<(DefId, TraitRef)>,
1119
1120     // The current self type if inside an impl (used for better errors).
1121     current_self_type: Option<Ty>,
1122
1123     // The idents for the primitive types.
1124     primitive_type_table: PrimitiveTypeTable,
1125
1126     def_map: RefCell<DefMap>,
1127     freevars: FreevarMap,
1128     freevars_seen: NodeMap<NodeMap<usize>>,
1129     export_map: ExportMap,
1130     trait_map: TraitMap,
1131     external_exports: ExternalExports,
1132
1133     // Whether or not to print error messages. Can be set to true
1134     // when getting additional info for error message suggestions,
1135     // so as to avoid printing duplicate errors
1136     emit_errors: bool,
1137
1138     make_glob_map: bool,
1139     // Maps imports to the names of items actually imported (this actually maps
1140     // all imports, but only glob imports are actually interesting).
1141     glob_map: GlobMap,
1142
1143     used_imports: HashSet<(NodeId, Namespace)>,
1144     used_crates: HashSet<CrateNum>,
1145
1146     // Callback function for intercepting walks
1147     callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>,
1148     // The intention is that the callback modifies this flag.
1149     // Once set, the resolver falls out of the walk, preserving the ribs.
1150     resolved: bool,
1151
1152     arenas: &'a ResolverArenas<'a>,
1153 }
1154
1155 pub struct ResolverArenas<'a> {
1156     modules: arena::TypedArena<ModuleS<'a>>,
1157     name_bindings: arena::TypedArena<NameBinding<'a>>,
1158 }
1159
1160 #[derive(PartialEq)]
1161 enum FallbackChecks {
1162     Everything,
1163     OnlyTraitAndStatics,
1164 }
1165
1166 impl<'a, 'tcx> Resolver<'a, 'tcx> {
1167     fn new(session: &'a Session,
1168            ast_map: &'a hir_map::Map<'tcx>,
1169            make_glob_map: MakeGlobMap,
1170            arenas: &'a ResolverArenas<'a>)
1171            -> Resolver<'a, 'tcx> {
1172         let root_def_id = ast_map.local_def_id(CRATE_NODE_ID);
1173         let graph_root = ModuleS::new(NoParentLink, Some(Def::Mod(root_def_id)), false, true);
1174         let graph_root = arenas.modules.alloc(graph_root);
1175
1176         Resolver {
1177             session: session,
1178
1179             ast_map: ast_map,
1180
1181             // The outermost module has def ID 0; this is not reflected in the
1182             // AST.
1183             graph_root: graph_root,
1184
1185             trait_item_map: FnvHashMap(),
1186             structs: FnvHashMap(),
1187
1188             unresolved_imports: 0,
1189
1190             current_module: graph_root,
1191             value_ribs: Vec::new(),
1192             type_ribs: Vec::new(),
1193             label_ribs: Vec::new(),
1194
1195             current_trait_ref: None,
1196             current_self_type: None,
1197
1198             primitive_type_table: PrimitiveTypeTable::new(),
1199
1200             def_map: RefCell::new(NodeMap()),
1201             freevars: NodeMap(),
1202             freevars_seen: NodeMap(),
1203             export_map: NodeMap(),
1204             trait_map: NodeMap(),
1205             used_imports: HashSet::new(),
1206             used_crates: HashSet::new(),
1207             external_exports: DefIdSet(),
1208
1209             emit_errors: true,
1210             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1211             glob_map: HashMap::new(),
1212
1213             callback: None,
1214             resolved: false,
1215
1216             arenas: arenas,
1217         }
1218     }
1219
1220     fn arenas() -> ResolverArenas<'a> {
1221         ResolverArenas {
1222             modules: arena::TypedArena::new(),
1223             name_bindings: arena::TypedArena::new(),
1224         }
1225     }
1226
1227     fn new_module(&self,
1228                   parent_link: ParentLink<'a>,
1229                   def: Option<Def>,
1230                   external: bool,
1231                   is_public: bool) -> Module<'a> {
1232         self.arenas.modules.alloc(ModuleS::new(parent_link, def, external, is_public))
1233     }
1234
1235     fn new_name_binding(&self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1236         self.arenas.name_bindings.alloc(name_binding)
1237     }
1238
1239     fn new_extern_crate_module(&self, parent_link: ParentLink<'a>, def: Def) -> Module<'a> {
1240         let mut module = ModuleS::new(parent_link, Some(def), false, true);
1241         module.is_extern_crate = true;
1242         self.arenas.modules.alloc(module)
1243     }
1244
1245     fn get_ribs<'b>(&'b mut self, ns: Namespace) -> &'b mut Vec<Rib<'a>> {
1246         match ns { ValueNS => &mut self.value_ribs, TypeNS => &mut self.type_ribs }
1247     }
1248
1249     #[inline]
1250     fn record_use(&mut self, name: Name, ns: Namespace, binding: &'a NameBinding<'a>) {
1251         // track extern crates for unused_extern_crate lint
1252         if let Some(DefId { krate, .. }) = binding.module().and_then(ModuleS::def_id) {
1253             self.used_crates.insert(krate);
1254         }
1255
1256         let import_id = match binding.kind {
1257             NameBindingKind::Import { id, .. } => id,
1258             _ => return,
1259         };
1260
1261         self.used_imports.insert((import_id, ns));
1262
1263         if !self.make_glob_map {
1264             return;
1265         }
1266         if self.glob_map.contains_key(&import_id) {
1267             self.glob_map.get_mut(&import_id).unwrap().insert(name);
1268             return;
1269         }
1270
1271         let mut new_set = HashSet::new();
1272         new_set.insert(name);
1273         self.glob_map.insert(import_id, new_set);
1274     }
1275
1276     fn get_trait_name(&self, did: DefId) -> Name {
1277         if let Some(node_id) = self.ast_map.as_local_node_id(did) {
1278             self.ast_map.expect_item(node_id).name
1279         } else {
1280             self.session.cstore.item_name(did)
1281         }
1282     }
1283
1284     /// Resolves the given module path from the given root `module_`.
1285     fn resolve_module_path_from_root(&mut self,
1286                                      module_: Module<'a>,
1287                                      module_path: &[Name],
1288                                      index: usize,
1289                                      span: Span,
1290                                      lp: LastPrivate)
1291                                      -> ResolveResult<(Module<'a>, LastPrivate)> {
1292         fn search_parent_externals(needle: Name, module: Module) -> Option<Module> {
1293             match module.resolve_name(needle, TypeNS, false) {
1294                 Success(binding) if binding.is_extern_crate() => Some(module),
1295                 _ => match module.parent_link {
1296                     ModuleParentLink(ref parent, _) => {
1297                         search_parent_externals(needle, parent)
1298                     }
1299                     _ => None,
1300                 },
1301             }
1302         }
1303
1304         let mut search_module = module_;
1305         let mut index = index;
1306         let module_path_len = module_path.len();
1307         let mut closest_private = lp;
1308
1309         // Resolve the module part of the path. This does not involve looking
1310         // upward though scope chains; we simply resolve names directly in
1311         // modules as we go.
1312         while index < module_path_len {
1313             let name = module_path[index];
1314             match self.resolve_name_in_module(search_module, name, TypeNS, false, true) {
1315                 Failed(None) => {
1316                     let segment_name = name.as_str();
1317                     let module_name = module_to_string(search_module);
1318                     let mut span = span;
1319                     let msg = if "???" == &module_name {
1320                         span.hi = span.lo + Pos::from_usize(segment_name.len());
1321
1322                         match search_parent_externals(name, &self.current_module) {
1323                             Some(module) => {
1324                                 let path_str = names_to_string(module_path);
1325                                 let target_mod_str = module_to_string(&module);
1326                                 let current_mod_str = module_to_string(&self.current_module);
1327
1328                                 let prefix = if target_mod_str == current_mod_str {
1329                                     "self::".to_string()
1330                                 } else {
1331                                     format!("{}::", target_mod_str)
1332                                 };
1333
1334                                 format!("Did you mean `{}{}`?", prefix, path_str)
1335                             }
1336                             None => format!("Maybe a missing `extern crate {}`?", segment_name),
1337                         }
1338                     } else {
1339                         format!("Could not find `{}` in `{}`", segment_name, module_name)
1340                     };
1341
1342                     return Failed(Some((span, msg)));
1343                 }
1344                 Failed(err) => return Failed(err),
1345                 Indeterminate => {
1346                     debug!("(resolving module path for import) module resolution is \
1347                             indeterminate: {}",
1348                            name);
1349                     return Indeterminate;
1350                 }
1351                 Success(binding) => {
1352                     // Check to see whether there are type bindings, and, if
1353                     // so, whether there is a module within.
1354                     if let Some(module_def) = binding.module() {
1355                         search_module = module_def;
1356
1357                         // Keep track of the closest private module used
1358                         // when resolving this import chain.
1359                         if !binding.is_public() {
1360                             if let Some(did) = search_module.def_id() {
1361                                 closest_private = LastMod(DependsOn(did));
1362                             }
1363                         }
1364                     } else {
1365                         let msg = format!("Not a module `{}`", name);
1366                         return Failed(Some((span, msg)));
1367                     }
1368                 }
1369             }
1370
1371             index += 1;
1372         }
1373
1374         return Success((search_module, closest_private));
1375     }
1376
1377     /// Attempts to resolve the module part of an import directive or path
1378     /// rooted at the given module.
1379     ///
1380     /// On success, returns the resolved module, and the closest *private*
1381     /// module found to the destination when resolving this path.
1382     fn resolve_module_path(&mut self,
1383                            module_: Module<'a>,
1384                            module_path: &[Name],
1385                            use_lexical_scope: UseLexicalScopeFlag,
1386                            span: Span)
1387                            -> ResolveResult<(Module<'a>, LastPrivate)> {
1388         if module_path.len() == 0 {
1389             return Success((self.graph_root, LastMod(AllPublic))) // Use the crate root
1390         }
1391
1392         debug!("(resolving module path for import) processing `{}` rooted at `{}`",
1393                names_to_string(module_path),
1394                module_to_string(&module_));
1395
1396         // Resolve the module prefix, if any.
1397         let module_prefix_result = self.resolve_module_prefix(module_, module_path);
1398
1399         let search_module;
1400         let start_index;
1401         let last_private;
1402         match module_prefix_result {
1403             Failed(None) => {
1404                 let mpath = names_to_string(module_path);
1405                 let mpath = &mpath[..];
1406                 match mpath.rfind(':') {
1407                     Some(idx) => {
1408                         let msg = format!("Could not find `{}` in `{}`",
1409                                           // idx +- 1 to account for the
1410                                           // colons on either side
1411                                           &mpath[idx + 1..],
1412                                           &mpath[..idx - 1]);
1413                         return Failed(Some((span, msg)));
1414                     }
1415                     None => {
1416                         return Failed(None);
1417                     }
1418                 }
1419             }
1420             Failed(err) => return Failed(err),
1421             Indeterminate => {
1422                 debug!("(resolving module path for import) indeterminate; bailing");
1423                 return Indeterminate;
1424             }
1425             Success(NoPrefixFound) => {
1426                 // There was no prefix, so we're considering the first element
1427                 // of the path. How we handle this depends on whether we were
1428                 // instructed to use lexical scope or not.
1429                 match use_lexical_scope {
1430                     DontUseLexicalScope => {
1431                         // This is a crate-relative path. We will start the
1432                         // resolution process at index zero.
1433                         search_module = self.graph_root;
1434                         start_index = 0;
1435                         last_private = LastMod(AllPublic);
1436                     }
1437                     UseLexicalScope => {
1438                         // This is not a crate-relative path. We resolve the
1439                         // first component of the path in the current lexical
1440                         // scope and then proceed to resolve below that.
1441                         match self.resolve_item_in_lexical_scope(module_,
1442                                                                  module_path[0],
1443                                                                  TypeNS,
1444                                                                  true) {
1445                             Failed(err) => return Failed(err),
1446                             Indeterminate => {
1447                                 debug!("(resolving module path for import) indeterminate; bailing");
1448                                 return Indeterminate;
1449                             }
1450                             Success(binding) => match binding.module() {
1451                                 Some(containing_module) => {
1452                                     search_module = containing_module;
1453                                     start_index = 1;
1454                                     last_private = LastMod(AllPublic);
1455                                 }
1456                                 None => return Failed(None),
1457                             }
1458                         }
1459                     }
1460                 }
1461             }
1462             Success(PrefixFound(ref containing_module, index)) => {
1463                 search_module = containing_module;
1464                 start_index = index;
1465                 last_private = LastMod(DependsOn(containing_module.def_id()
1466                                                                   .unwrap()));
1467             }
1468         }
1469
1470         self.resolve_module_path_from_root(search_module,
1471                                            module_path,
1472                                            start_index,
1473                                            span,
1474                                            last_private)
1475     }
1476
1477     /// Invariant: This must only be called during main resolution, not during
1478     /// import resolution.
1479     fn resolve_item_in_lexical_scope(&mut self,
1480                                      module_: Module<'a>,
1481                                      name: Name,
1482                                      namespace: Namespace,
1483                                      record_used: bool)
1484                                      -> ResolveResult<&'a NameBinding<'a>> {
1485         debug!("(resolving item in lexical scope) resolving `{}` in namespace {:?} in `{}`",
1486                name,
1487                namespace,
1488                module_to_string(&module_));
1489
1490         // Proceed up the scope chain looking for parent modules.
1491         let mut search_module = module_;
1492         loop {
1493             // Resolve the name in the parent module.
1494             match self.resolve_name_in_module(search_module, name, namespace, true, record_used) {
1495                 Failed(Some((span, msg))) => {
1496                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1497                 }
1498                 Failed(None) => (), // Continue up the search chain.
1499                 Indeterminate => {
1500                     // We couldn't see through the higher scope because of an
1501                     // unresolved import higher up. Bail.
1502
1503                     debug!("(resolving item in lexical scope) indeterminate higher scope; bailing");
1504                     return Indeterminate;
1505                 }
1506                 Success(binding) => {
1507                     // We found the module.
1508                     debug!("(resolving item in lexical scope) found name in module, done");
1509                     return Success(binding);
1510                 }
1511             }
1512
1513             // Go to the next parent.
1514             match search_module.parent_link {
1515                 NoParentLink => {
1516                     // No more parents. This module was unresolved.
1517                     debug!("(resolving item in lexical scope) unresolved module: no parent module");
1518                     return Failed(None);
1519                 }
1520                 ModuleParentLink(parent_module_node, _) => {
1521                     if search_module.is_normal() {
1522                         // We stop the search here.
1523                         debug!("(resolving item in lexical scope) unresolved module: not \
1524                                 searching through module parents");
1525                             return Failed(None);
1526                     } else {
1527                         search_module = parent_module_node;
1528                     }
1529                 }
1530                 BlockParentLink(parent_module_node, _) => {
1531                     search_module = parent_module_node;
1532                 }
1533             }
1534         }
1535     }
1536
1537     /// Returns the nearest normal module parent of the given module.
1538     fn get_nearest_normal_module_parent(&mut self, module_: Module<'a>) -> Option<Module<'a>> {
1539         let mut module_ = module_;
1540         loop {
1541             match module_.parent_link {
1542                 NoParentLink => return None,
1543                 ModuleParentLink(new_module, _) |
1544                 BlockParentLink(new_module, _) => {
1545                     let new_module = new_module;
1546                     if new_module.is_normal() {
1547                         return Some(new_module);
1548                     }
1549                     module_ = new_module;
1550                 }
1551             }
1552         }
1553     }
1554
1555     /// Returns the nearest normal module parent of the given module, or the
1556     /// module itself if it is a normal module.
1557     fn get_nearest_normal_module_parent_or_self(&mut self, module_: Module<'a>) -> Module<'a> {
1558         if module_.is_normal() {
1559             return module_;
1560         }
1561         match self.get_nearest_normal_module_parent(module_) {
1562             None => module_,
1563             Some(new_module) => new_module,
1564         }
1565     }
1566
1567     /// Resolves a "module prefix". A module prefix is one or both of (a) `self::`;
1568     /// (b) some chain of `super::`.
1569     /// grammar: (SELF MOD_SEP ) ? (SUPER MOD_SEP) *
1570     fn resolve_module_prefix(&mut self,
1571                              module_: Module<'a>,
1572                              module_path: &[Name])
1573                              -> ResolveResult<ModulePrefixResult<'a>> {
1574         // Start at the current module if we see `self` or `super`, or at the
1575         // top of the crate otherwise.
1576         let mut i = match &*module_path[0].as_str() {
1577             "self" => 1,
1578             "super" => 0,
1579             _ => return Success(NoPrefixFound),
1580         };
1581         let mut containing_module = self.get_nearest_normal_module_parent_or_self(module_);
1582
1583         // Now loop through all the `super`s we find.
1584         while i < module_path.len() && "super" == module_path[i].as_str() {
1585             debug!("(resolving module prefix) resolving `super` at {}",
1586                    module_to_string(&containing_module));
1587             match self.get_nearest_normal_module_parent(containing_module) {
1588                 None => return Failed(None),
1589                 Some(new_module) => {
1590                     containing_module = new_module;
1591                     i += 1;
1592                 }
1593             }
1594         }
1595
1596         debug!("(resolving module prefix) finished resolving prefix at {}",
1597                module_to_string(&containing_module));
1598
1599         return Success(PrefixFound(containing_module, i));
1600     }
1601
1602     /// Attempts to resolve the supplied name in the given module for the
1603     /// given namespace. If successful, returns the binding corresponding to
1604     /// the name.
1605     fn resolve_name_in_module(&mut self,
1606                               module: Module<'a>,
1607                               name: Name,
1608                               namespace: Namespace,
1609                               allow_private_imports: bool,
1610                               record_used: bool)
1611                               -> ResolveResult<&'a NameBinding<'a>> {
1612         debug!("(resolving name in module) resolving `{}` in `{}`", name, module_to_string(module));
1613
1614         build_reduced_graph::populate_module_if_necessary(self, module);
1615         module.resolve_name(name, namespace, allow_private_imports).and_then(|binding| {
1616             if record_used {
1617                 self.record_use(name, namespace, binding);
1618             }
1619             Success(binding)
1620         })
1621     }
1622
1623     fn report_unresolved_imports(&mut self, module_: Module<'a>) {
1624         for import in module_.unresolved_imports.borrow().iter() {
1625             resolve_error(self, import.span, ResolutionError::UnresolvedImport(None));
1626             break;
1627         }
1628
1629         // Descend into children and anonymous children.
1630         for (_, module_) in module_.module_children.borrow().iter() {
1631             self.report_unresolved_imports(module_);
1632         }
1633     }
1634
1635     // AST resolution
1636     //
1637     // We maintain a list of value ribs and type ribs.
1638     //
1639     // Simultaneously, we keep track of the current position in the module
1640     // graph in the `current_module` pointer. When we go to resolve a name in
1641     // the value or type namespaces, we first look through all the ribs and
1642     // then query the module graph. When we resolve a name in the module
1643     // namespace, we can skip all the ribs (since nested modules are not
1644     // allowed within blocks in Rust) and jump straight to the current module
1645     // graph node.
1646     //
1647     // Named implementations are handled separately. When we find a method
1648     // call, we consult the module node to find all of the implementations in
1649     // scope. This information is lazily cached in the module node. We then
1650     // generate a fake "implementation scope" containing all the
1651     // implementations thus found, for compatibility with old resolve pass.
1652
1653     fn with_scope<F>(&mut self, id: NodeId, f: F)
1654         where F: FnOnce(&mut Resolver)
1655     {
1656         let orig_module = self.current_module;
1657
1658         // Move down in the graph.
1659         if let Some(module) = orig_module.module_children.borrow().get(&id) {
1660             self.current_module = module;
1661         }
1662
1663         f(self);
1664
1665         self.current_module = orig_module;
1666     }
1667
1668     /// Searches the current set of local scopes for labels.
1669     /// Stops after meeting a closure.
1670     fn search_label(&self, name: Name) -> Option<DefLike> {
1671         for rib in self.label_ribs.iter().rev() {
1672             match rib.kind {
1673                 NormalRibKind => {
1674                     // Continue
1675                 }
1676                 _ => {
1677                     // Do not resolve labels across function boundary
1678                     return None;
1679                 }
1680             }
1681             let result = rib.bindings.get(&name).cloned();
1682             if result.is_some() {
1683                 return result;
1684             }
1685         }
1686         None
1687     }
1688
1689     fn resolve_crate(&mut self, krate: &hir::Crate) {
1690         debug!("(resolving crate) starting");
1691
1692         intravisit::walk_crate(self, krate);
1693     }
1694
1695     fn check_if_primitive_type_name(&self, name: Name, span: Span) {
1696         if let Some(_) = self.primitive_type_table.primitive_types.get(&name) {
1697             span_err!(self.session,
1698                       span,
1699                       E0317,
1700                       "user-defined types or type parameters cannot shadow the primitive types");
1701         }
1702     }
1703
1704     fn resolve_item(&mut self, item: &Item) {
1705         let name = item.name;
1706
1707         debug!("(resolving item) resolving {}", name);
1708
1709         match item.node {
1710             ItemEnum(_, ref generics) |
1711             ItemTy(_, ref generics) |
1712             ItemStruct(_, ref generics) => {
1713                 self.check_if_primitive_type_name(name, item.span);
1714
1715                 self.with_type_parameter_rib(HasTypeParameters(generics, TypeSpace, ItemRibKind),
1716                                              |this| intravisit::walk_item(this, item));
1717             }
1718             ItemFn(_, _, _, _, ref generics, _) => {
1719                 self.with_type_parameter_rib(HasTypeParameters(generics, FnSpace, ItemRibKind),
1720                                              |this| intravisit::walk_item(this, item));
1721             }
1722
1723             ItemDefaultImpl(_, ref trait_ref) => {
1724                 self.with_optional_trait_ref(Some(trait_ref), |_, _| {});
1725             }
1726             ItemImpl(_, _, ref generics, ref opt_trait_ref, ref self_type, ref impl_items) => {
1727                 self.resolve_implementation(generics,
1728                                             opt_trait_ref,
1729                                             &self_type,
1730                                             item.id,
1731                                             impl_items);
1732             }
1733
1734             ItemTrait(_, ref generics, ref bounds, ref trait_items) => {
1735                 self.check_if_primitive_type_name(name, item.span);
1736
1737                 // Create a new rib for the trait-wide type parameters.
1738                 self.with_type_parameter_rib(HasTypeParameters(generics,
1739                                                                TypeSpace,
1740                                                                ItemRibKind),
1741                                              |this| {
1742                     let local_def_id = this.ast_map.local_def_id(item.id);
1743                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1744                         this.visit_generics(generics);
1745                         walk_list!(this, visit_ty_param_bound, bounds);
1746
1747                         for trait_item in trait_items {
1748                             match trait_item.node {
1749                                 hir::ConstTraitItem(_, ref default) => {
1750                                     // Only impose the restrictions of
1751                                     // ConstRibKind if there's an actual constant
1752                                     // expression in a provided default.
1753                                     if default.is_some() {
1754                                         this.with_constant_rib(|this| {
1755                                             intravisit::walk_trait_item(this, trait_item)
1756                                         });
1757                                     } else {
1758                                         intravisit::walk_trait_item(this, trait_item)
1759                                     }
1760                                 }
1761                                 hir::MethodTraitItem(ref sig, _) => {
1762                                     let type_parameters =
1763                                         HasTypeParameters(&sig.generics,
1764                                                           FnSpace,
1765                                                           MethodRibKind);
1766                                     this.with_type_parameter_rib(type_parameters, |this| {
1767                                         intravisit::walk_trait_item(this, trait_item)
1768                                     });
1769                                 }
1770                                 hir::TypeTraitItem(..) => {
1771                                     this.check_if_primitive_type_name(trait_item.name,
1772                                                                       trait_item.span);
1773                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1774                                         intravisit::walk_trait_item(this, trait_item)
1775                                     });
1776                                 }
1777                             };
1778                         }
1779                     });
1780                 });
1781             }
1782
1783             ItemMod(_) | ItemForeignMod(_) => {
1784                 self.with_scope(item.id, |this| {
1785                     intravisit::walk_item(this, item);
1786                 });
1787             }
1788
1789             ItemConst(..) | ItemStatic(..) => {
1790                 self.with_constant_rib(|this| {
1791                     intravisit::walk_item(this, item);
1792                 });
1793             }
1794
1795             ItemUse(ref view_path) => {
1796                 // check for imports shadowing primitive types
1797                 let check_rename = |this: &Self, id, name| {
1798                     match this.def_map.borrow().get(&id).map(|d| d.full_def()) {
1799                         Some(Def::Enum(..)) | Some(Def::TyAlias(..)) | Some(Def::Struct(..)) |
1800                         Some(Def::Trait(..)) | None => {
1801                             this.check_if_primitive_type_name(name, item.span);
1802                         }
1803                         _ => {}
1804                     }
1805                 };
1806
1807                 match view_path.node {
1808                     hir::ViewPathSimple(name, _) => {
1809                         check_rename(self, item.id, name);
1810                     }
1811                     hir::ViewPathList(ref prefix, ref items) => {
1812                         for item in items {
1813                             if let Some(name) = item.node.rename() {
1814                                 check_rename(self, item.node.id(), name);
1815                             }
1816                         }
1817
1818                         // Resolve prefix of an import with empty braces (issue #28388)
1819                         if items.is_empty() && !prefix.segments.is_empty() {
1820                             match self.resolve_crate_relative_path(prefix.span,
1821                                                                    &prefix.segments,
1822                                                                    TypeNS) {
1823                                 Some((def, lp)) =>
1824                                     self.record_def(item.id, PathResolution::new(def, lp, 0)),
1825                                 None => {
1826                                     resolve_error(self,
1827                                                   prefix.span,
1828                                                   ResolutionError::FailedToResolve(
1829                                                       &path_names_to_string(prefix, 0)));
1830                                     self.record_def(item.id, err_path_resolution());
1831                                 }
1832                             }
1833                         }
1834                     }
1835                     _ => {}
1836                 }
1837             }
1838
1839             ItemExternCrate(_) => {
1840                 // do nothing, these are just around to be encoded
1841             }
1842         }
1843     }
1844
1845     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1846         where F: FnOnce(&mut Resolver)
1847     {
1848         match type_parameters {
1849             HasTypeParameters(generics, space, rib_kind) => {
1850                 let mut function_type_rib = Rib::new(rib_kind);
1851                 let mut seen_bindings = HashSet::new();
1852                 for (index, type_parameter) in generics.ty_params.iter().enumerate() {
1853                     let name = type_parameter.name;
1854                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1855
1856                     if seen_bindings.contains(&name) {
1857                         resolve_error(self,
1858                                       type_parameter.span,
1859                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name));
1860                     }
1861                     seen_bindings.insert(name);
1862
1863                     // plain insert (no renaming)
1864                     function_type_rib.bindings
1865                                      .insert(name,
1866                                              DlDef(Def::TyParam(space,
1867                                                               index as u32,
1868                                                               self.ast_map
1869                                                                   .local_def_id(type_parameter.id),
1870                                                               name)));
1871                 }
1872                 self.type_ribs.push(function_type_rib);
1873             }
1874
1875             NoTypeParameters => {
1876                 // Nothing to do.
1877             }
1878         }
1879
1880         f(self);
1881
1882         match type_parameters {
1883             HasTypeParameters(..) => {
1884                 if !self.resolved {
1885                     self.type_ribs.pop();
1886                 }
1887             }
1888             NoTypeParameters => {}
1889         }
1890     }
1891
1892     fn with_label_rib<F>(&mut self, f: F)
1893         where F: FnOnce(&mut Resolver)
1894     {
1895         self.label_ribs.push(Rib::new(NormalRibKind));
1896         f(self);
1897         if !self.resolved {
1898             self.label_ribs.pop();
1899         }
1900     }
1901
1902     fn with_constant_rib<F>(&mut self, f: F)
1903         where F: FnOnce(&mut Resolver)
1904     {
1905         self.value_ribs.push(Rib::new(ConstantItemRibKind));
1906         self.type_ribs.push(Rib::new(ConstantItemRibKind));
1907         f(self);
1908         if !self.resolved {
1909             self.type_ribs.pop();
1910             self.value_ribs.pop();
1911         }
1912     }
1913
1914     fn resolve_function(&mut self, rib_kind: RibKind<'a>, declaration: &FnDecl, block: &Block) {
1915         // Create a value rib for the function.
1916         self.value_ribs.push(Rib::new(rib_kind));
1917
1918         // Create a label rib for the function.
1919         self.label_ribs.push(Rib::new(rib_kind));
1920
1921         // Add each argument to the rib.
1922         let mut bindings_list = HashMap::new();
1923         for argument in &declaration.inputs {
1924             self.resolve_pattern(&argument.pat, ArgumentIrrefutableMode, &mut bindings_list);
1925
1926             self.visit_ty(&argument.ty);
1927
1928             debug!("(resolving function) recorded argument");
1929         }
1930         intravisit::walk_fn_ret_ty(self, &declaration.output);
1931
1932         // Resolve the function body.
1933         self.visit_block(block);
1934
1935         debug!("(resolving function) leaving function");
1936
1937         if !self.resolved {
1938             self.label_ribs.pop();
1939             self.value_ribs.pop();
1940         }
1941     }
1942
1943     fn resolve_trait_reference(&mut self,
1944                                id: NodeId,
1945                                trait_path: &Path,
1946                                path_depth: usize)
1947                                -> Result<PathResolution, ()> {
1948         if let Some(path_res) = self.resolve_path(id, trait_path, path_depth, TypeNS, true) {
1949             if let Def::Trait(_) = path_res.base_def {
1950                 debug!("(resolving trait) found trait def: {:?}", path_res);
1951                 Ok(path_res)
1952             } else {
1953                 let mut err =
1954                     resolve_struct_error(self,
1955                                   trait_path.span,
1956                                   ResolutionError::IsNotATrait(&path_names_to_string(trait_path,
1957                                                                                       path_depth)));
1958
1959                 // If it's a typedef, give a note
1960                 if let Def::TyAlias(..) = path_res.base_def {
1961                     err.span_note(trait_path.span,
1962                                   "`type` aliases cannot be used for traits");
1963                 }
1964                 err.emit();
1965                 Err(())
1966             }
1967         } else {
1968
1969             // find possible candidates
1970             let trait_name = trait_path.segments.last().unwrap().identifier.name;
1971             let candidates =
1972                 self.lookup_candidates(
1973                     trait_name,
1974                     TypeNS,
1975                     |def| match def {
1976                         Def::Trait(_) => true,
1977                         _             => false,
1978                     },
1979                 );
1980
1981             // create error object
1982             let name = &path_names_to_string(trait_path, path_depth);
1983             let error =
1984                 ResolutionError::UndeclaredTraitName(
1985                     name,
1986                     candidates,
1987                 );
1988
1989             resolve_error(self, trait_path.span, error);
1990             Err(())
1991         }
1992     }
1993
1994     fn resolve_generics(&mut self, generics: &Generics) {
1995         for type_parameter in generics.ty_params.iter() {
1996             self.check_if_primitive_type_name(type_parameter.name, type_parameter.span);
1997         }
1998         for predicate in &generics.where_clause.predicates {
1999             match predicate {
2000                 &hir::WherePredicate::BoundPredicate(_) |
2001                 &hir::WherePredicate::RegionPredicate(_) => {}
2002                 &hir::WherePredicate::EqPredicate(ref eq_pred) => {
2003                     let path_res = self.resolve_path(eq_pred.id, &eq_pred.path, 0, TypeNS, true);
2004                     if let Some(PathResolution { base_def: Def::TyParam(..), .. }) = path_res {
2005                         self.record_def(eq_pred.id, path_res.unwrap());
2006                     } else {
2007                         resolve_error(self,
2008                                       eq_pred.span,
2009                                       ResolutionError::UndeclaredAssociatedType);
2010                         self.record_def(eq_pred.id, err_path_resolution());
2011                     }
2012                 }
2013             }
2014         }
2015         intravisit::walk_generics(self, generics);
2016     }
2017
2018     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
2019         where F: FnOnce(&mut Resolver) -> T
2020     {
2021         // Handle nested impls (inside fn bodies)
2022         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
2023         let result = f(self);
2024         self.current_self_type = previous_value;
2025         result
2026     }
2027
2028     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
2029         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
2030     {
2031         let mut new_val = None;
2032         let mut new_id = None;
2033         if let Some(trait_ref) = opt_trait_ref {
2034             if let Ok(path_res) = self.resolve_trait_reference(trait_ref.ref_id,
2035                                                                &trait_ref.path,
2036                                                                0) {
2037                 assert!(path_res.depth == 0);
2038                 self.record_def(trait_ref.ref_id, path_res);
2039                 new_val = Some((path_res.base_def.def_id(), trait_ref.clone()));
2040                 new_id = Some(path_res.base_def.def_id());
2041             } else {
2042                 self.record_def(trait_ref.ref_id, err_path_resolution());
2043             }
2044             intravisit::walk_trait_ref(self, trait_ref);
2045         }
2046         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
2047         let result = f(self, new_id);
2048         self.current_trait_ref = original_trait_ref;
2049         result
2050     }
2051
2052     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
2053         where F: FnOnce(&mut Resolver)
2054     {
2055         let mut self_type_rib = Rib::new(NormalRibKind);
2056
2057         // plain insert (no renaming, types are not currently hygienic....)
2058         let name = special_names::type_self;
2059         self_type_rib.bindings.insert(name, DlDef(self_def));
2060         self.type_ribs.push(self_type_rib);
2061         f(self);
2062         if !self.resolved {
2063             self.type_ribs.pop();
2064         }
2065     }
2066
2067     fn resolve_implementation(&mut self,
2068                               generics: &Generics,
2069                               opt_trait_reference: &Option<TraitRef>,
2070                               self_type: &Ty,
2071                               item_id: NodeId,
2072                               impl_items: &[ImplItem]) {
2073         // If applicable, create a rib for the type parameters.
2074         self.with_type_parameter_rib(HasTypeParameters(generics,
2075                                                        TypeSpace,
2076                                                        ItemRibKind),
2077                                      |this| {
2078             // Resolve the type parameters.
2079             this.visit_generics(generics);
2080
2081             // Resolve the trait reference, if necessary.
2082             this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
2083                 // Resolve the self type.
2084                 this.visit_ty(self_type);
2085
2086                 this.with_self_rib(Def::SelfTy(trait_id, Some((item_id, self_type.id))), |this| {
2087                     this.with_current_self_type(self_type, |this| {
2088                         for impl_item in impl_items {
2089                             match impl_item.node {
2090                                 hir::ImplItemKind::Const(..) => {
2091                                     // If this is a trait impl, ensure the const
2092                                     // exists in trait
2093                                     this.check_trait_item(impl_item.name,
2094                                                           impl_item.span,
2095                                         |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
2096                                     this.with_constant_rib(|this| {
2097                                         intravisit::walk_impl_item(this, impl_item);
2098                                     });
2099                                 }
2100                                 hir::ImplItemKind::Method(ref sig, _) => {
2101                                     // If this is a trait impl, ensure the method
2102                                     // exists in trait
2103                                     this.check_trait_item(impl_item.name,
2104                                                           impl_item.span,
2105                                         |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
2106
2107                                     // We also need a new scope for the method-
2108                                     // specific type parameters.
2109                                     let type_parameters =
2110                                         HasTypeParameters(&sig.generics,
2111                                                           FnSpace,
2112                                                           MethodRibKind);
2113                                     this.with_type_parameter_rib(type_parameters, |this| {
2114                                         intravisit::walk_impl_item(this, impl_item);
2115                                     });
2116                                 }
2117                                 hir::ImplItemKind::Type(ref ty) => {
2118                                     // If this is a trait impl, ensure the type
2119                                     // exists in trait
2120                                     this.check_trait_item(impl_item.name,
2121                                                           impl_item.span,
2122                                         |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
2123
2124                                     this.visit_ty(ty);
2125                                 }
2126                             }
2127                         }
2128                     });
2129                 });
2130             });
2131         });
2132     }
2133
2134     fn check_trait_item<F>(&self, name: Name, span: Span, err: F)
2135         where F: FnOnce(Name, &str) -> ResolutionError
2136     {
2137         // If there is a TraitRef in scope for an impl, then the method must be in the
2138         // trait.
2139         if let Some((did, ref trait_ref)) = self.current_trait_ref {
2140             if !self.trait_item_map.contains_key(&(name, did)) {
2141                 let path_str = path_names_to_string(&trait_ref.path, 0);
2142                 resolve_error(self, span, err(name, &path_str));
2143             }
2144         }
2145     }
2146
2147     fn resolve_local(&mut self, local: &Local) {
2148         // Resolve the type.
2149         walk_list!(self, visit_ty, &local.ty);
2150
2151         // Resolve the initializer.
2152         walk_list!(self, visit_expr, &local.init);
2153
2154         // Resolve the pattern.
2155         self.resolve_pattern(&local.pat, LocalIrrefutableMode, &mut HashMap::new());
2156     }
2157
2158     // build a map from pattern identifiers to binding-info's.
2159     // this is done hygienically. This could arise for a macro
2160     // that expands into an or-pattern where one 'x' was from the
2161     // user and one 'x' came from the macro.
2162     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2163         let mut result = HashMap::new();
2164         pat_bindings(&self.def_map, pat, |binding_mode, _id, sp, path1| {
2165             let name = path1.node;
2166             result.insert(name,
2167                           BindingInfo {
2168                               span: sp,
2169                               binding_mode: binding_mode,
2170                           });
2171         });
2172         return result;
2173     }
2174
2175     // check that all of the arms in an or-pattern have exactly the
2176     // same set of bindings, with the same binding modes for each.
2177     fn check_consistent_bindings(&mut self, arm: &Arm) {
2178         if arm.pats.is_empty() {
2179             return;
2180         }
2181         let map_0 = self.binding_mode_map(&arm.pats[0]);
2182         for (i, p) in arm.pats.iter().enumerate() {
2183             let map_i = self.binding_mode_map(&p);
2184
2185             for (&key, &binding_0) in &map_0 {
2186                 match map_i.get(&key) {
2187                     None => {
2188                         resolve_error(self,
2189                                       p.span,
2190                                       ResolutionError::VariableNotBoundInPattern(key, i + 1));
2191                     }
2192                     Some(binding_i) => {
2193                         if binding_0.binding_mode != binding_i.binding_mode {
2194                             resolve_error(self,
2195                                           binding_i.span,
2196                                           ResolutionError::VariableBoundWithDifferentMode(key,
2197                                                                                           i + 1));
2198                         }
2199                     }
2200                 }
2201             }
2202
2203             for (&key, &binding) in &map_i {
2204                 if !map_0.contains_key(&key) {
2205                     resolve_error(self,
2206                                   binding.span,
2207                                   ResolutionError::VariableNotBoundInParentPattern(key, i + 1));
2208                 }
2209             }
2210         }
2211     }
2212
2213     fn resolve_arm(&mut self, arm: &Arm) {
2214         self.value_ribs.push(Rib::new(NormalRibKind));
2215
2216         let mut bindings_list = HashMap::new();
2217         for pattern in &arm.pats {
2218             self.resolve_pattern(&pattern, RefutableMode, &mut bindings_list);
2219         }
2220
2221         // This has to happen *after* we determine which
2222         // pat_idents are variants
2223         self.check_consistent_bindings(arm);
2224
2225         walk_list!(self, visit_expr, &arm.guard);
2226         self.visit_expr(&arm.body);
2227
2228         if !self.resolved {
2229             self.value_ribs.pop();
2230         }
2231     }
2232
2233     fn resolve_block(&mut self, block: &Block) {
2234         debug!("(resolving block) entering block");
2235         // Move down in the graph, if there's an anonymous module rooted here.
2236         let orig_module = self.current_module;
2237         let anonymous_module =
2238             orig_module.module_children.borrow().get(&block.id).map(|module| *module);
2239
2240         if let Some(anonymous_module) = anonymous_module {
2241             debug!("(resolving block) found anonymous module, moving down");
2242             self.value_ribs.push(Rib::new(AnonymousModuleRibKind(anonymous_module)));
2243             self.type_ribs.push(Rib::new(AnonymousModuleRibKind(anonymous_module)));
2244             self.current_module = anonymous_module;
2245         } else {
2246             self.value_ribs.push(Rib::new(NormalRibKind));
2247         }
2248
2249         // Descend into the block.
2250         intravisit::walk_block(self, block);
2251
2252         // Move back up.
2253         if !self.resolved {
2254             self.current_module = orig_module;
2255             self.value_ribs.pop();
2256             if let Some(_) = anonymous_module {
2257                 self.type_ribs.pop();
2258             }
2259         }
2260         debug!("(resolving block) leaving block");
2261     }
2262
2263     fn resolve_type(&mut self, ty: &Ty) {
2264         match ty.node {
2265             TyPath(ref maybe_qself, ref path) => {
2266                 let resolution = match self.resolve_possibly_assoc_item(ty.id,
2267                                                                         maybe_qself.as_ref(),
2268                                                                         path,
2269                                                                         TypeNS,
2270                                                                         true) {
2271                     // `<T>::a::b::c` is resolved by typeck alone.
2272                     TypecheckRequired => {
2273                         // Resolve embedded types.
2274                         intravisit::walk_ty(self, ty);
2275                         return;
2276                     }
2277                     ResolveAttempt(resolution) => resolution,
2278                 };
2279
2280                 // This is a path in the type namespace. Walk through scopes
2281                 // looking for it.
2282                 match resolution {
2283                     Some(def) => {
2284                         // Write the result into the def map.
2285                         debug!("(resolving type) writing resolution for `{}` (id {}) = {:?}",
2286                                path_names_to_string(path, 0),
2287                                ty.id,
2288                                def);
2289                         self.record_def(ty.id, def);
2290                     }
2291                     None => {
2292                         self.record_def(ty.id, err_path_resolution());
2293
2294                         // Keep reporting some errors even if they're ignored above.
2295                         self.resolve_path(ty.id, path, 0, TypeNS, true);
2296
2297                         let kind = if maybe_qself.is_some() {
2298                             "associated type"
2299                         } else {
2300                             "type name"
2301                         };
2302
2303                         let self_type_name = special_idents::type_self.name;
2304                         let is_invalid_self_type_name = path.segments.len() > 0 &&
2305                                                         maybe_qself.is_none() &&
2306                                                         path.segments[0].identifier.name ==
2307                                                         self_type_name;
2308                         if is_invalid_self_type_name {
2309                             resolve_error(self,
2310                                           ty.span,
2311                                           ResolutionError::SelfUsedOutsideImplOrTrait);
2312                         } else {
2313                             let segment = path.segments.last();
2314                             let segment = segment.expect("missing name in path");
2315                             let type_name = segment.identifier.name;
2316
2317                             let candidates =
2318                                 self.lookup_candidates(
2319                                     type_name,
2320                                     TypeNS,
2321                                     |def| match def {
2322                                         Def::Trait(_) |
2323                                         Def::Enum(_) |
2324                                         Def::Struct(_) |
2325                                         Def::TyAlias(_) => true,
2326                                         _               => false,
2327                                     },
2328                                 );
2329
2330                             // create error object
2331                             let name = &path_names_to_string(path, 0);
2332                             let error =
2333                                 ResolutionError::UseOfUndeclared(
2334                                     kind,
2335                                     name,
2336                                     candidates,
2337                                 );
2338
2339                             resolve_error(self, ty.span, error);
2340                         }
2341                     }
2342                 }
2343             }
2344             _ => {}
2345         }
2346         // Resolve embedded types.
2347         intravisit::walk_ty(self, ty);
2348     }
2349
2350     fn resolve_pattern(&mut self,
2351                        pattern: &Pat,
2352                        mode: PatternBindingMode,
2353                        // Maps idents to the node ID for the (outermost)
2354                        // pattern that binds them
2355                        bindings_list: &mut HashMap<Name, NodeId>) {
2356         let pat_id = pattern.id;
2357         walk_pat(pattern, |pattern| {
2358             match pattern.node {
2359                 PatKind::Ident(binding_mode, ref path1, ref at_rhs) => {
2360                     // The meaning of PatKind::Ident with no type parameters
2361                     // depends on whether an enum variant or unit-like struct
2362                     // with that name is in scope. The probing lookup has to
2363                     // be careful not to emit spurious errors. Only matching
2364                     // patterns (match) can match nullary variants or
2365                     // unit-like structs. For binding patterns (let
2366                     // and the LHS of @-patterns), matching such a value is
2367                     // simply disallowed (since it's rarely what you want).
2368                     let const_ok = mode == RefutableMode && at_rhs.is_none();
2369
2370                     let ident = path1.node;
2371                     let renamed = ident.name;
2372
2373                     match self.resolve_bare_identifier_pattern(ident.unhygienic_name,
2374                                                                pattern.span) {
2375                         FoundStructOrEnumVariant(def, lp) if const_ok => {
2376                             debug!("(resolving pattern) resolving `{}` to struct or enum variant",
2377                                    renamed);
2378
2379                             self.enforce_default_binding_mode(pattern,
2380                                                               binding_mode,
2381                                                               "an enum variant");
2382                             self.record_def(pattern.id,
2383                                             PathResolution {
2384                                                 base_def: def,
2385                                                 last_private: lp,
2386                                                 depth: 0,
2387                                             });
2388                         }
2389                         FoundStructOrEnumVariant(..) => {
2390                             resolve_error(
2391                                 self,
2392                                 pattern.span,
2393                                 ResolutionError::DeclarationShadowsEnumVariantOrUnitLikeStruct(
2394                                     renamed)
2395                             );
2396                             self.record_def(pattern.id, err_path_resolution());
2397                         }
2398                         FoundConst(def, lp, _) if const_ok => {
2399                             debug!("(resolving pattern) resolving `{}` to constant", renamed);
2400
2401                             self.enforce_default_binding_mode(pattern, binding_mode, "a constant");
2402                             self.record_def(pattern.id,
2403                                             PathResolution {
2404                                                 base_def: def,
2405                                                 last_private: lp,
2406                                                 depth: 0,
2407                                             });
2408                         }
2409                         FoundConst(def, _, name) => {
2410                             resolve_error(
2411                                 self,
2412                                 pattern.span,
2413                                 ResolutionError::OnlyIrrefutablePatternsAllowedHere(def.def_id(),
2414                                                                                     name)
2415                             );
2416                             self.record_def(pattern.id, err_path_resolution());
2417                         }
2418                         BareIdentifierPatternUnresolved => {
2419                             debug!("(resolving pattern) binding `{}`", renamed);
2420
2421                             let def_id = self.ast_map.local_def_id(pattern.id);
2422                             let def = Def::Local(def_id, pattern.id);
2423
2424                             // Record the definition so that later passes
2425                             // will be able to distinguish variants from
2426                             // locals in patterns.
2427
2428                             self.record_def(pattern.id,
2429                                             PathResolution {
2430                                                 base_def: def,
2431                                                 last_private: LastMod(AllPublic),
2432                                                 depth: 0,
2433                                             });
2434
2435                             // Add the binding to the local ribs, if it
2436                             // doesn't already exist in the bindings list. (We
2437                             // must not add it if it's in the bindings list
2438                             // because that breaks the assumptions later
2439                             // passes make about or-patterns.)
2440                             if !bindings_list.contains_key(&renamed) {
2441                                 let this = &mut *self;
2442                                 let last_rib = this.value_ribs.last_mut().unwrap();
2443                                 last_rib.bindings.insert(renamed, DlDef(def));
2444                                 bindings_list.insert(renamed, pat_id);
2445                             } else if mode == ArgumentIrrefutableMode &&
2446                                bindings_list.contains_key(&renamed) {
2447                                 // Forbid duplicate bindings in the same
2448                                 // parameter list.
2449                                 resolve_error(
2450                                     self,
2451                                     pattern.span,
2452                                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2453                                         &ident.name.as_str())
2454                                 );
2455                             } else if bindings_list.get(&renamed) == Some(&pat_id) {
2456                                 // Then this is a duplicate variable in the
2457                                 // same disjunction, which is an error.
2458                                 resolve_error(
2459                                     self,
2460                                     pattern.span,
2461                                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2462                                         &ident.name.as_str())
2463                                 );
2464                             }
2465                             // Else, not bound in the same pattern: do
2466                             // nothing.
2467                         }
2468                     }
2469                 }
2470
2471                 PatKind::TupleStruct(ref path, _) | PatKind::Path(ref path) => {
2472                     // This must be an enum variant, struct or const.
2473                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2474                                                                             None,
2475                                                                             path,
2476                                                                             ValueNS,
2477                                                                             false) {
2478                         // The below shouldn't happen because all
2479                         // qualified paths should be in PatKind::QPath.
2480                         TypecheckRequired =>
2481                             self.session.span_bug(path.span,
2482                                                   "resolve_possibly_assoc_item claimed that a path \
2483                                                    in PatKind::Path or PatKind::TupleStruct \
2484                                                    requires typecheck to resolve, but qualified \
2485                                                    paths should be PatKind::QPath"),
2486                         ResolveAttempt(resolution) => resolution,
2487                     };
2488                     if let Some(path_res) = resolution {
2489                         match path_res.base_def {
2490                             Def::Struct(..) if path_res.depth == 0 => {
2491                                 self.record_def(pattern.id, path_res);
2492                             }
2493                             Def::Variant(..) | Def::Const(..) => {
2494                                 self.record_def(pattern.id, path_res);
2495                             }
2496                             Def::Static(..) => {
2497                                 resolve_error(&self,
2498                                               path.span,
2499                                               ResolutionError::StaticVariableReference);
2500                                 self.record_def(pattern.id, err_path_resolution());
2501                             }
2502                             _ => {
2503                                 // If anything ends up here entirely resolved,
2504                                 // it's an error. If anything ends up here
2505                                 // partially resolved, that's OK, because it may
2506                                 // be a `T::CONST` that typeck will resolve.
2507                                 if path_res.depth == 0 {
2508                                     resolve_error(
2509                                         self,
2510                                         path.span,
2511                                         ResolutionError::NotAnEnumVariantStructOrConst(
2512                                             &path.segments
2513                                                  .last()
2514                                                  .unwrap()
2515                                                  .identifier
2516                                                  .name
2517                                                  .as_str())
2518                                     );
2519                                     self.record_def(pattern.id, err_path_resolution());
2520                                 } else {
2521                                     let const_name = path.segments
2522                                                          .last()
2523                                                          .unwrap()
2524                                                          .identifier
2525                                                          .name;
2526                                     let traits = self.get_traits_containing_item(const_name);
2527                                     self.trait_map.insert(pattern.id, traits);
2528                                     self.record_def(pattern.id, path_res);
2529                                 }
2530                             }
2531                         }
2532                     } else {
2533                         resolve_error(
2534                             self,
2535                             path.span,
2536                             ResolutionError::UnresolvedEnumVariantStructOrConst(
2537                                 &path.segments.last().unwrap().identifier.name.as_str())
2538                         );
2539                         self.record_def(pattern.id, err_path_resolution());
2540                     }
2541                     intravisit::walk_path(self, path);
2542                 }
2543
2544                 PatKind::QPath(ref qself, ref path) => {
2545                     // Associated constants only.
2546                     let resolution = match self.resolve_possibly_assoc_item(pat_id,
2547                                                                             Some(qself),
2548                                                                             path,
2549                                                                             ValueNS,
2550                                                                             false) {
2551                         TypecheckRequired => {
2552                             // All `<T>::CONST` should end up here, and will
2553                             // require use of the trait map to resolve
2554                             // during typechecking.
2555                             let const_name = path.segments
2556                                                  .last()
2557                                                  .unwrap()
2558                                                  .identifier
2559                                                  .name;
2560                             let traits = self.get_traits_containing_item(const_name);
2561                             self.trait_map.insert(pattern.id, traits);
2562                             intravisit::walk_pat(self, pattern);
2563                             return true;
2564                         }
2565                         ResolveAttempt(resolution) => resolution,
2566                     };
2567                     if let Some(path_res) = resolution {
2568                         match path_res.base_def {
2569                             // All `<T as Trait>::CONST` should end up here, and
2570                             // have the trait already selected.
2571                             Def::AssociatedConst(..) => {
2572                                 self.record_def(pattern.id, path_res);
2573                             }
2574                             _ => {
2575                                 resolve_error(
2576                                     self,
2577                                     path.span,
2578                                     ResolutionError::NotAnAssociatedConst(
2579                                         &path.segments.last().unwrap().identifier.name.as_str()
2580                                     )
2581                                 );
2582                                 self.record_def(pattern.id, err_path_resolution());
2583                             }
2584                         }
2585                     } else {
2586                         resolve_error(self,
2587                                       path.span,
2588                                       ResolutionError::UnresolvedAssociatedConst(&path.segments
2589                                                                                       .last()
2590                                                                                       .unwrap()
2591                                                                                       .identifier
2592                                                                                       .name
2593                                                                                       .as_str()));
2594                         self.record_def(pattern.id, err_path_resolution());
2595                     }
2596                     intravisit::walk_pat(self, pattern);
2597                 }
2598
2599                 PatKind::Struct(ref path, _, _) => {
2600                     match self.resolve_path(pat_id, path, 0, TypeNS, false) {
2601                         Some(definition) => {
2602                             self.record_def(pattern.id, definition);
2603                         }
2604                         result => {
2605                             debug!("(resolving pattern) didn't find struct def: {:?}", result);
2606                             resolve_error(
2607                                 self,
2608                                 path.span,
2609                                 ResolutionError::DoesNotNameAStruct(
2610                                     &path_names_to_string(path, 0))
2611                             );
2612                             self.record_def(pattern.id, err_path_resolution());
2613                         }
2614                     }
2615                     intravisit::walk_path(self, path);
2616                 }
2617
2618                 PatKind::Lit(_) | PatKind::Range(..) => {
2619                     intravisit::walk_pat(self, pattern);
2620                 }
2621
2622                 _ => {
2623                     // Nothing to do.
2624                 }
2625             }
2626             true
2627         });
2628     }
2629
2630     fn resolve_bare_identifier_pattern(&mut self,
2631                                        name: Name,
2632                                        span: Span)
2633                                        -> BareIdentifierPatternResolution {
2634         let module = self.current_module;
2635         match self.resolve_item_in_lexical_scope(module, name, ValueNS, true) {
2636             Success(binding) => {
2637                 debug!("(resolve bare identifier pattern) succeeded in finding {} at {:?}",
2638                        name,
2639                        binding);
2640                 match binding.def() {
2641                     None => {
2642                         panic!("resolved name in the value namespace to a set of name bindings \
2643                                 with no def?!");
2644                     }
2645                     // For the two success cases, this lookup can be
2646                     // considered as not having a private component because
2647                     // the lookup happened only within the current module.
2648                     Some(def @ Def::Variant(..)) | Some(def @ Def::Struct(..)) => {
2649                         return FoundStructOrEnumVariant(def, LastMod(AllPublic));
2650                     }
2651                     Some(def @ Def::Const(..)) | Some(def @ Def::AssociatedConst(..)) => {
2652                         return FoundConst(def, LastMod(AllPublic), name);
2653                     }
2654                     Some(Def::Static(..)) => {
2655                         resolve_error(self, span, ResolutionError::StaticVariableReference);
2656                         return BareIdentifierPatternUnresolved;
2657                     }
2658                     _ => return BareIdentifierPatternUnresolved
2659                 }
2660             }
2661
2662             Indeterminate => return BareIdentifierPatternUnresolved,
2663             Failed(err) => {
2664                 match err {
2665                     Some((span, msg)) => {
2666                         resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2667                     }
2668                     None => (),
2669                 }
2670
2671                 debug!("(resolve bare identifier pattern) failed to find {}", name);
2672                 return BareIdentifierPatternUnresolved;
2673             }
2674         }
2675     }
2676
2677     /// Handles paths that may refer to associated items
2678     fn resolve_possibly_assoc_item(&mut self,
2679                                    id: NodeId,
2680                                    maybe_qself: Option<&hir::QSelf>,
2681                                    path: &Path,
2682                                    namespace: Namespace,
2683                                    check_ribs: bool)
2684                                    -> AssocItemResolveResult {
2685         let max_assoc_types;
2686
2687         match maybe_qself {
2688             Some(qself) => {
2689                 if qself.position == 0 {
2690                     return TypecheckRequired;
2691                 }
2692                 max_assoc_types = path.segments.len() - qself.position;
2693                 // Make sure the trait is valid.
2694                 let _ = self.resolve_trait_reference(id, path, max_assoc_types);
2695             }
2696             None => {
2697                 max_assoc_types = path.segments.len();
2698             }
2699         }
2700
2701         let mut resolution = self.with_no_errors(|this| {
2702             this.resolve_path(id, path, 0, namespace, check_ribs)
2703         });
2704         for depth in 1..max_assoc_types {
2705             if resolution.is_some() {
2706                 break;
2707             }
2708             self.with_no_errors(|this| {
2709                 resolution = this.resolve_path(id, path, depth, TypeNS, true);
2710             });
2711         }
2712         if let Some(Def::Mod(_)) = resolution.map(|r| r.base_def) {
2713             // A module is not a valid type or value.
2714             resolution = None;
2715         }
2716         ResolveAttempt(resolution)
2717     }
2718
2719     /// If `check_ribs` is true, checks the local definitions first; i.e.
2720     /// doesn't skip straight to the containing module.
2721     /// Skips `path_depth` trailing segments, which is also reflected in the
2722     /// returned value. See `middle::def::PathResolution` for more info.
2723     pub fn resolve_path(&mut self,
2724                         id: NodeId,
2725                         path: &Path,
2726                         path_depth: usize,
2727                         namespace: Namespace,
2728                         check_ribs: bool)
2729                         -> Option<PathResolution> {
2730         let span = path.span;
2731         let segments = &path.segments[..path.segments.len() - path_depth];
2732
2733         let mk_res = |(def, lp)| PathResolution::new(def, lp, path_depth);
2734
2735         if path.global {
2736             let def = self.resolve_crate_relative_path(span, segments, namespace);
2737             return def.map(mk_res);
2738         }
2739
2740         // Try to find a path to an item in a module.
2741         let last_ident = segments.last().unwrap().identifier;
2742         if segments.len() <= 1 {
2743             let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, true);
2744             return unqualified_def.and_then(|def| self.adjust_local_def(def, span))
2745                                   .map(|def| {
2746                                       PathResolution::new(def, LastMod(AllPublic), path_depth)
2747                                   });
2748         }
2749
2750         let unqualified_def = self.resolve_identifier(last_ident, namespace, check_ribs, false);
2751         let def = self.resolve_module_relative_path(span, segments, namespace);
2752         match (def, unqualified_def) {
2753             (Some((ref d, _)), Some(ref ud)) if *d == ud.def => {
2754                 self.session
2755                     .add_lint(lint::builtin::UNUSED_QUALIFICATIONS,
2756                               id,
2757                               span,
2758                               "unnecessary qualification".to_string());
2759             }
2760             _ => {}
2761         }
2762
2763         def.map(mk_res)
2764     }
2765
2766     // Resolve a single identifier
2767     fn resolve_identifier(&mut self,
2768                           identifier: hir::Ident,
2769                           namespace: Namespace,
2770                           check_ribs: bool,
2771                           record_used: bool)
2772                           -> Option<LocalDef> {
2773         if identifier.name == special_idents::invalid.name {
2774             return Some(LocalDef::from_def(Def::Err));
2775         }
2776
2777         // First, check to see whether the name is a primitive type.
2778         if namespace == TypeNS {
2779             if let Some(&prim_ty) = self.primitive_type_table
2780                                         .primitive_types
2781                                         .get(&identifier.unhygienic_name) {
2782                 return Some(LocalDef::from_def(Def::PrimTy(prim_ty)));
2783             }
2784         }
2785
2786         if check_ribs {
2787             if let Some(def) = self.resolve_identifier_in_local_ribs(identifier, namespace) {
2788                 return Some(def);
2789             }
2790         }
2791
2792         // Check the items.
2793         let module = self.current_module;
2794         let name = identifier.unhygienic_name;
2795         match self.resolve_item_in_lexical_scope(module, name, namespace, record_used) {
2796             Success(binding) => binding.def().map(LocalDef::from_def),
2797             Failed(Some((span, msg))) => {
2798                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2799                 None
2800             }
2801             _ => None,
2802         }
2803     }
2804
2805     // Resolve a local definition, potentially adjusting for closures.
2806     fn adjust_local_def(&mut self, local_def: LocalDef, span: Span) -> Option<Def> {
2807         let ribs = match local_def.ribs {
2808             Some((TypeNS, i)) => &self.type_ribs[i + 1..],
2809             Some((ValueNS, i)) => &self.value_ribs[i + 1..],
2810             _ => &[] as &[_],
2811         };
2812         let mut def = local_def.def;
2813         match def {
2814             Def::Upvar(..) => {
2815                 self.session.span_bug(span, &format!("unexpected {:?} in bindings", def))
2816             }
2817             Def::Local(_, node_id) => {
2818                 for rib in ribs {
2819                     match rib.kind {
2820                         NormalRibKind | AnonymousModuleRibKind(..) => {
2821                             // Nothing to do. Continue.
2822                         }
2823                         ClosureRibKind(function_id) => {
2824                             let prev_def = def;
2825                             let node_def_id = self.ast_map.local_def_id(node_id);
2826
2827                             let seen = self.freevars_seen
2828                                            .entry(function_id)
2829                                            .or_insert_with(|| NodeMap());
2830                             if let Some(&index) = seen.get(&node_id) {
2831                                 def = Def::Upvar(node_def_id, node_id, index, function_id);
2832                                 continue;
2833                             }
2834                             let vec = self.freevars
2835                                           .entry(function_id)
2836                                           .or_insert_with(|| vec![]);
2837                             let depth = vec.len();
2838                             vec.push(Freevar {
2839                                 def: prev_def,
2840                                 span: span,
2841                             });
2842
2843                             def = Def::Upvar(node_def_id, node_id, depth, function_id);
2844                             seen.insert(node_id, depth);
2845                         }
2846                         ItemRibKind | MethodRibKind => {
2847                             // This was an attempt to access an upvar inside a
2848                             // named function item. This is not allowed, so we
2849                             // report an error.
2850                             resolve_error(self,
2851                                           span,
2852                                           ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2853                             return None;
2854                         }
2855                         ConstantItemRibKind => {
2856                             // Still doesn't deal with upvars
2857                             resolve_error(self,
2858                                           span,
2859                                           ResolutionError::AttemptToUseNonConstantValueInConstant);
2860                             return None;
2861                         }
2862                     }
2863                 }
2864             }
2865             Def::TyParam(..) | Def::SelfTy(..) => {
2866                 for rib in ribs {
2867                     match rib.kind {
2868                         NormalRibKind | MethodRibKind | ClosureRibKind(..) |
2869                         AnonymousModuleRibKind(..) => {
2870                             // Nothing to do. Continue.
2871                         }
2872                         ItemRibKind => {
2873                             // This was an attempt to use a type parameter outside
2874                             // its scope.
2875
2876                             resolve_error(self,
2877                                           span,
2878                                           ResolutionError::TypeParametersFromOuterFunction);
2879                             return None;
2880                         }
2881                         ConstantItemRibKind => {
2882                             // see #9186
2883                             resolve_error(self, span, ResolutionError::OuterTypeParameterContext);
2884                             return None;
2885                         }
2886                     }
2887                 }
2888             }
2889             _ => {}
2890         }
2891         return Some(def);
2892     }
2893
2894     // resolve a "module-relative" path, e.g. a::b::c
2895     fn resolve_module_relative_path(&mut self,
2896                                     span: Span,
2897                                     segments: &[hir::PathSegment],
2898                                     namespace: Namespace)
2899                                     -> Option<(Def, LastPrivate)> {
2900         let module_path = segments.split_last()
2901                                   .unwrap()
2902                                   .1
2903                                   .iter()
2904                                   .map(|ps| ps.identifier.name)
2905                                   .collect::<Vec<_>>();
2906
2907         let containing_module;
2908         let last_private;
2909         let current_module = self.current_module;
2910         match self.resolve_module_path(current_module, &module_path, UseLexicalScope, span) {
2911             Failed(err) => {
2912                 let (span, msg) = match err {
2913                     Some((span, msg)) => (span, msg),
2914                     None => {
2915                         let msg = format!("Use of undeclared type or module `{}`",
2916                                           names_to_string(&module_path));
2917                         (span, msg)
2918                     }
2919                 };
2920
2921                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2922                 return None;
2923             }
2924             Indeterminate => return None,
2925             Success((resulting_module, resulting_last_private)) => {
2926                 containing_module = resulting_module;
2927                 last_private = resulting_last_private;
2928             }
2929         }
2930
2931         let name = segments.last().unwrap().identifier.name;
2932         let result = self.resolve_name_in_module(containing_module, name, namespace, false, true);
2933         let def = match result {
2934             Success(binding) => {
2935                 let (def, lp) = binding.def_and_lp();
2936                 (def, last_private.or(lp))
2937             }
2938             _ => return None,
2939         };
2940         return Some(def);
2941     }
2942
2943     /// Invariant: This must be called only during main resolution, not during
2944     /// import resolution.
2945     fn resolve_crate_relative_path(&mut self,
2946                                    span: Span,
2947                                    segments: &[hir::PathSegment],
2948                                    namespace: Namespace)
2949                                    -> Option<(Def, LastPrivate)> {
2950         let module_path = segments.split_last()
2951                                   .unwrap()
2952                                   .1
2953                                   .iter()
2954                                   .map(|ps| ps.identifier.name)
2955                                   .collect::<Vec<_>>();
2956
2957         let root_module = self.graph_root;
2958
2959         let containing_module;
2960         let last_private;
2961         match self.resolve_module_path_from_root(root_module,
2962                                                  &module_path,
2963                                                  0,
2964                                                  span,
2965                                                  LastMod(AllPublic)) {
2966             Failed(err) => {
2967                 let (span, msg) = match err {
2968                     Some((span, msg)) => (span, msg),
2969                     None => {
2970                         let msg = format!("Use of undeclared module `::{}`",
2971                                           names_to_string(&module_path));
2972                         (span, msg)
2973                     }
2974                 };
2975
2976                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2977                 return None;
2978             }
2979
2980             Indeterminate => return None,
2981
2982             Success((resulting_module, resulting_last_private)) => {
2983                 containing_module = resulting_module;
2984                 last_private = resulting_last_private;
2985             }
2986         }
2987
2988         let name = segments.last().unwrap().identifier.name;
2989         match self.resolve_name_in_module(containing_module, name, namespace, false, true) {
2990             Success(binding) => {
2991                 let (def, lp) = binding.def_and_lp();
2992                 Some((def, last_private.or(lp)))
2993             }
2994             _ => None,
2995         }
2996     }
2997
2998     fn resolve_identifier_in_local_ribs(&mut self,
2999                                         ident: hir::Ident,
3000                                         namespace: Namespace)
3001                                         -> Option<LocalDef> {
3002         // Check the local set of ribs.
3003         let name = match namespace { ValueNS => ident.name, TypeNS => ident.unhygienic_name };
3004
3005         for i in (0 .. self.get_ribs(namespace).len()).rev() {
3006             if let Some(def_like) = self.get_ribs(namespace)[i].bindings.get(&name).cloned() {
3007                 match def_like {
3008                     DlDef(def) => {
3009                         debug!("(resolving path in local ribs) resolved `{}` to {:?} at {}",
3010                                name,
3011                                def,
3012                                i);
3013                         return Some(LocalDef {
3014                             ribs: Some((namespace, i)),
3015                             def: def,
3016                         });
3017                     }
3018                     def_like => {
3019                         debug!("(resolving path in local ribs) resolved `{}` to pseudo-def {:?}",
3020                                name,
3021                                def_like);
3022                         return None;
3023                     }
3024                 }
3025             }
3026
3027             if let AnonymousModuleRibKind(module) = self.get_ribs(namespace)[i].kind {
3028                 if let Success(binding) = self.resolve_name_in_module(module,
3029                                                                       ident.unhygienic_name,
3030                                                                       namespace,
3031                                                                       true,
3032                                                                       true) {
3033                     if let Some(def) = binding.def() {
3034                         return Some(LocalDef::from_def(def));
3035                     }
3036                 }
3037             }
3038         }
3039
3040         None
3041     }
3042
3043     fn with_no_errors<T, F>(&mut self, f: F) -> T
3044         where F: FnOnce(&mut Resolver) -> T
3045     {
3046         self.emit_errors = false;
3047         let rs = f(self);
3048         self.emit_errors = true;
3049         rs
3050     }
3051
3052     fn find_fallback_in_self_type(&mut self, name: Name) -> FallbackSuggestion {
3053         fn extract_path_and_node_id(t: &Ty,
3054                                     allow: FallbackChecks)
3055                                     -> Option<(Path, NodeId, FallbackChecks)> {
3056             match t.node {
3057                 TyPath(None, ref path) => Some((path.clone(), t.id, allow)),
3058                 TyPtr(ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, OnlyTraitAndStatics),
3059                 TyRptr(_, ref mut_ty) => extract_path_and_node_id(&mut_ty.ty, allow),
3060                 // This doesn't handle the remaining `Ty` variants as they are not
3061                 // that commonly the self_type, it might be interesting to provide
3062                 // support for those in future.
3063                 _ => None,
3064             }
3065         }
3066
3067         fn get_module<'a, 'tcx>(this: &mut Resolver<'a, 'tcx>,
3068                                 span: Span,
3069                                 name_path: &[ast::Name])
3070                                 -> Option<Module<'a>> {
3071             let root = this.current_module;
3072             let last_name = name_path.last().unwrap();
3073
3074             if name_path.len() == 1 {
3075                 match this.primitive_type_table.primitive_types.get(last_name) {
3076                     Some(_) => None,
3077                     None => this.current_module.resolve_name(*last_name, TypeNS, true).success()
3078                                                .and_then(NameBinding::module)
3079                 }
3080             } else {
3081                 match this.resolve_module_path(root, &name_path, UseLexicalScope, span) {
3082                     Success((module, _)) => Some(module),
3083                     _ => None,
3084                 }
3085             }
3086         }
3087
3088         fn is_static_method(this: &Resolver, did: DefId) -> bool {
3089             if let Some(node_id) = this.ast_map.as_local_node_id(did) {
3090                 let sig = match this.ast_map.get(node_id) {
3091                     hir_map::NodeTraitItem(trait_item) => match trait_item.node {
3092                         hir::MethodTraitItem(ref sig, _) => sig,
3093                         _ => return false,
3094                     },
3095                     hir_map::NodeImplItem(impl_item) => match impl_item.node {
3096                         hir::ImplItemKind::Method(ref sig, _) => sig,
3097                         _ => return false,
3098                     },
3099                     _ => return false,
3100                 };
3101                 sig.explicit_self.node == hir::SelfStatic
3102             } else {
3103                 this.session.cstore.is_static_method(did)
3104             }
3105         }
3106
3107         let (path, node_id, allowed) = match self.current_self_type {
3108             Some(ref ty) => match extract_path_and_node_id(ty, Everything) {
3109                 Some(x) => x,
3110                 None => return NoSuggestion,
3111             },
3112             None => return NoSuggestion,
3113         };
3114
3115         if allowed == Everything {
3116             // Look for a field with the same name in the current self_type.
3117             match self.def_map.borrow().get(&node_id).map(|d| d.full_def()) {
3118                 Some(Def::Enum(did)) |
3119                 Some(Def::TyAlias(did)) |
3120                 Some(Def::Struct(did)) |
3121                 Some(Def::Variant(_, did)) => match self.structs.get(&did) {
3122                     None => {}
3123                     Some(fields) => {
3124                         if fields.iter().any(|&field_name| name == field_name) {
3125                             return Field;
3126                         }
3127                     }
3128                 },
3129                 _ => {} // Self type didn't resolve properly
3130             }
3131         }
3132
3133         let name_path = path.segments.iter().map(|seg| seg.identifier.name).collect::<Vec<_>>();
3134
3135         // Look for a method in the current self type's impl module.
3136         if let Some(module) = get_module(self, path.span, &name_path) {
3137             if let Success(binding) = module.resolve_name(name, ValueNS, true) {
3138                 if let Some(Def::Method(did)) = binding.def() {
3139                     if is_static_method(self, did) {
3140                         return StaticMethod(path_names_to_string(&path, 0));
3141                     }
3142                     if self.current_trait_ref.is_some() {
3143                         return TraitItem;
3144                     } else if allowed == Everything {
3145                         return Method;
3146                     }
3147                 }
3148             }
3149         }
3150
3151         // Look for a method in the current trait.
3152         if let Some((trait_did, ref trait_ref)) = self.current_trait_ref {
3153             if let Some(&did) = self.trait_item_map.get(&(name, trait_did)) {
3154                 if is_static_method(self, did) {
3155                     return TraitMethod(path_names_to_string(&trait_ref.path, 0));
3156                 } else {
3157                     return TraitItem;
3158                 }
3159             }
3160         }
3161
3162         NoSuggestion
3163     }
3164
3165     fn find_best_match(&mut self, name: &str) -> SuggestionType {
3166         if let Some(macro_name) = self.session.available_macros
3167                                   .borrow().iter().find(|n| n.as_str() == name) {
3168             return SuggestionType::Macro(format!("{}!", macro_name));
3169         }
3170
3171         let names = self.value_ribs
3172                     .iter()
3173                     .rev()
3174                     .flat_map(|rib| rib.bindings.keys());
3175
3176         if let Some(found) = find_best_match_for_name(names, name, None) {
3177             if name != found {
3178                 return SuggestionType::Function(found);
3179             }
3180         } SuggestionType::NotFound
3181     }
3182
3183     fn resolve_expr(&mut self, expr: &Expr) {
3184         // First, record candidate traits for this expression if it could
3185         // result in the invocation of a method call.
3186
3187         self.record_candidate_traits_for_expr_if_necessary(expr);
3188
3189         // Next, resolve the node.
3190         match expr.node {
3191             ExprPath(ref maybe_qself, ref path) => {
3192                 let resolution = match self.resolve_possibly_assoc_item(expr.id,
3193                                                                         maybe_qself.as_ref(),
3194                                                                         path,
3195                                                                         ValueNS,
3196                                                                         true) {
3197                     // `<T>::a::b::c` is resolved by typeck alone.
3198                     TypecheckRequired => {
3199                         let method_name = path.segments.last().unwrap().identifier.name;
3200                         let traits = self.get_traits_containing_item(method_name);
3201                         self.trait_map.insert(expr.id, traits);
3202                         intravisit::walk_expr(self, expr);
3203                         return;
3204                     }
3205                     ResolveAttempt(resolution) => resolution,
3206                 };
3207
3208                 // This is a local path in the value namespace. Walk through
3209                 // scopes looking for it.
3210                 if let Some(path_res) = resolution {
3211                     // Check if struct variant
3212                     let is_struct_variant = if let Def::Variant(_, variant_id) = path_res.base_def {
3213                         self.structs.contains_key(&variant_id)
3214                     } else {
3215                         false
3216                     };
3217                     if is_struct_variant {
3218                         let _ = self.structs.contains_key(&path_res.base_def.def_id());
3219                         let path_name = path_names_to_string(path, 0);
3220
3221                         let mut err = resolve_struct_error(self,
3222                                         expr.span,
3223                                         ResolutionError::StructVariantUsedAsFunction(&path_name));
3224
3225                         let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3226                                           path_name);
3227                         if self.emit_errors {
3228                             err.fileline_help(expr.span, &msg);
3229                         } else {
3230                             err.span_help(expr.span, &msg);
3231                         }
3232                         err.emit();
3233                         self.record_def(expr.id, err_path_resolution());
3234                     } else {
3235                         // Write the result into the def map.
3236                         debug!("(resolving expr) resolved `{}`",
3237                                path_names_to_string(path, 0));
3238
3239                         // Partial resolutions will need the set of traits in scope,
3240                         // so they can be completed during typeck.
3241                         if path_res.depth != 0 {
3242                             let method_name = path.segments.last().unwrap().identifier.name;
3243                             let traits = self.get_traits_containing_item(method_name);
3244                             self.trait_map.insert(expr.id, traits);
3245                         }
3246
3247                         self.record_def(expr.id, path_res);
3248                     }
3249                 } else {
3250                     // Be helpful if the name refers to a struct
3251                     // (The pattern matching def_tys where the id is in self.structs
3252                     // matches on regular structs while excluding tuple- and enum-like
3253                     // structs, which wouldn't result in this error.)
3254                     let path_name = path_names_to_string(path, 0);
3255                     let type_res = self.with_no_errors(|this| {
3256                         this.resolve_path(expr.id, path, 0, TypeNS, false)
3257                     });
3258
3259                     self.record_def(expr.id, err_path_resolution());
3260                     match type_res.map(|r| r.base_def) {
3261                         Some(Def::Struct(..)) => {
3262                             let mut err = resolve_struct_error(self,
3263                                 expr.span,
3264                                 ResolutionError::StructVariantUsedAsFunction(&path_name));
3265
3266                             let msg = format!("did you mean to write: `{} {{ /* fields */ }}`?",
3267                                               path_name);
3268                             if self.emit_errors {
3269                                 err.fileline_help(expr.span, &msg);
3270                             } else {
3271                                 err.span_help(expr.span, &msg);
3272                             }
3273                             err.emit();
3274                         }
3275                         _ => {
3276                             // Keep reporting some errors even if they're ignored above.
3277                             self.resolve_path(expr.id, path, 0, ValueNS, true);
3278
3279                             let mut method_scope = false;
3280                             self.value_ribs.iter().rev().all(|rib| {
3281                                 method_scope = match rib.kind {
3282                                     MethodRibKind => true,
3283                                     ItemRibKind | ConstantItemRibKind => false,
3284                                     _ => return true, // Keep advancing
3285                                 };
3286                                 false // Stop advancing
3287                             });
3288
3289                             if method_scope && special_names::self_.as_str() == &path_name[..] {
3290                                 resolve_error(self,
3291                                               expr.span,
3292                                               ResolutionError::SelfNotAvailableInStaticMethod);
3293                             } else {
3294                                 let last_name = path.segments.last().unwrap().identifier.name;
3295                                 let mut msg = match self.find_fallback_in_self_type(last_name) {
3296                                     NoSuggestion => {
3297                                         // limit search to 5 to reduce the number
3298                                         // of stupid suggestions
3299                                         match self.find_best_match(&path_name) {
3300                                             SuggestionType::Macro(s) => {
3301                                                 format!("the macro `{}`", s)
3302                                             }
3303                                             SuggestionType::Function(s) => format!("`{}`", s),
3304                                             SuggestionType::NotFound => "".to_string(),
3305                                         }
3306                                     }
3307                                     Field => format!("`self.{}`", path_name),
3308                                     Method |
3309                                     TraitItem => format!("to call `self.{}`", path_name),
3310                                     TraitMethod(path_str) |
3311                                     StaticMethod(path_str) =>
3312                                         format!("to call `{}::{}`", path_str, path_name),
3313                                 };
3314
3315                                 let mut context =  UnresolvedNameContext::Other;
3316                                 if !msg.is_empty() {
3317                                     msg = format!(". Did you mean {}?", msg);
3318                                 } else {
3319                                     // we check if this a module and if so, we display a help
3320                                     // message
3321                                     let name_path = path.segments.iter()
3322                                                         .map(|seg| seg.identifier.name)
3323                                                         .collect::<Vec<_>>();
3324                                     let current_module = self.current_module;
3325
3326                                     match self.resolve_module_path(current_module,
3327                                                                    &name_path[..],
3328                                                                    UseLexicalScope,
3329                                                                    expr.span) {
3330                                         Success(_) => {
3331                                             context = UnresolvedNameContext::PathIsMod(expr.id);
3332                                         },
3333                                         _ => {},
3334                                     };
3335                                 }
3336
3337                                 resolve_error(self,
3338                                               expr.span,
3339                                               ResolutionError::UnresolvedName(
3340                                                   &path_name, &msg, context));
3341                             }
3342                         }
3343                     }
3344                 }
3345
3346                 intravisit::walk_expr(self, expr);
3347             }
3348
3349             ExprStruct(ref path, _, _) => {
3350                 // Resolve the path to the structure it goes to. We don't
3351                 // check to ensure that the path is actually a structure; that
3352                 // is checked later during typeck.
3353                 match self.resolve_path(expr.id, path, 0, TypeNS, false) {
3354                     Some(definition) => self.record_def(expr.id, definition),
3355                     None => {
3356                         debug!("(resolving expression) didn't find struct def",);
3357
3358                         resolve_error(self,
3359                                       path.span,
3360                                       ResolutionError::DoesNotNameAStruct(
3361                                                                 &path_names_to_string(path, 0))
3362                                      );
3363                         self.record_def(expr.id, err_path_resolution());
3364                     }
3365                 }
3366
3367                 intravisit::walk_expr(self, expr);
3368             }
3369
3370             ExprLoop(_, Some(label)) | ExprWhile(_, _, Some(label)) => {
3371                 self.with_label_rib(|this| {
3372                     let def_like = DlDef(Def::Label(expr.id));
3373
3374                     {
3375                         let rib = this.label_ribs.last_mut().unwrap();
3376                         rib.bindings.insert(label.name, def_like);
3377                     }
3378
3379                     intravisit::walk_expr(this, expr);
3380                 })
3381             }
3382
3383             ExprBreak(Some(label)) | ExprAgain(Some(label)) => {
3384                 match self.search_label(label.node.name) {
3385                     None => {
3386                         self.record_def(expr.id, err_path_resolution());
3387                         resolve_error(self,
3388                                       label.span,
3389                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()))
3390                     }
3391                     Some(DlDef(def @ Def::Label(_))) => {
3392                         // Since this def is a label, it is never read.
3393                         self.record_def(expr.id,
3394                                         PathResolution {
3395                                             base_def: def,
3396                                             last_private: LastMod(AllPublic),
3397                                             depth: 0,
3398                                         })
3399                     }
3400                     Some(_) => {
3401                         self.session.span_bug(expr.span, "label wasn't mapped to a label def!")
3402                     }
3403                 }
3404             }
3405
3406             _ => {
3407                 intravisit::walk_expr(self, expr);
3408             }
3409         }
3410     }
3411
3412     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3413         match expr.node {
3414             ExprField(_, name) => {
3415                 // FIXME(#6890): Even though you can't treat a method like a
3416                 // field, we need to add any trait methods we find that match
3417                 // the field name so that we can do some nice error reporting
3418                 // later on in typeck.
3419                 let traits = self.get_traits_containing_item(name.node);
3420                 self.trait_map.insert(expr.id, traits);
3421             }
3422             ExprMethodCall(name, _, _) => {
3423                 debug!("(recording candidate traits for expr) recording traits for {}",
3424                        expr.id);
3425                 let traits = self.get_traits_containing_item(name.node);
3426                 self.trait_map.insert(expr.id, traits);
3427             }
3428             _ => {
3429                 // Nothing to do.
3430             }
3431         }
3432     }
3433
3434     fn get_traits_containing_item(&mut self, name: Name) -> Vec<DefId> {
3435         debug!("(getting traits containing item) looking for '{}'", name);
3436
3437         fn add_trait_info(found_traits: &mut Vec<DefId>, trait_def_id: DefId, name: Name) {
3438             debug!("(adding trait info) found trait {:?} for method '{}'",
3439                    trait_def_id,
3440                    name);
3441             found_traits.push(trait_def_id);
3442         }
3443
3444         let mut found_traits = Vec::new();
3445         let mut search_module = self.current_module;
3446         loop {
3447             // Look for the current trait.
3448             match self.current_trait_ref {
3449                 Some((trait_def_id, _)) => {
3450                     if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3451                         add_trait_info(&mut found_traits, trait_def_id, name);
3452                     }
3453                 }
3454                 None => {} // Nothing to do.
3455             }
3456
3457             // Look for trait children.
3458             build_reduced_graph::populate_module_if_necessary(self, &search_module);
3459
3460             search_module.for_each_child(|_, ns, name_binding| {
3461                 if ns != TypeNS { return }
3462                 let trait_def_id = match name_binding.def() {
3463                     Some(Def::Trait(trait_def_id)) => trait_def_id,
3464                     Some(..) | None => return,
3465                 };
3466                 if self.trait_item_map.contains_key(&(name, trait_def_id)) {
3467                     add_trait_info(&mut found_traits, trait_def_id, name);
3468                     let trait_name = self.get_trait_name(trait_def_id);
3469                     self.record_use(trait_name, TypeNS, name_binding);
3470                 }
3471             });
3472
3473             // Look for shadowed traits.
3474             for binding in search_module.shadowed_traits.borrow().iter() {
3475                 let did = binding.def().unwrap().def_id();
3476                 if self.trait_item_map.contains_key(&(name, did)) {
3477                     add_trait_info(&mut found_traits, did, name);
3478                     let trait_name = self.get_trait_name(did);
3479                     self.record_use(trait_name, TypeNS, binding);
3480                 }
3481             }
3482
3483             match search_module.parent_link {
3484                 NoParentLink | ModuleParentLink(..) => break,
3485                 BlockParentLink(parent_module, _) => {
3486                     search_module = parent_module;
3487                 }
3488             }
3489         }
3490
3491         found_traits
3492     }
3493
3494     /// When name resolution fails, this method can be used to look up candidate
3495     /// entities with the expected name. It allows filtering them using the
3496     /// supplied predicate (which should be used to only accept the types of
3497     /// definitions expected e.g. traits). The lookup spans across all crates.
3498     ///
3499     /// NOTE: The method does not look into imports, but this is not a problem,
3500     /// since we report the definitions (thus, the de-aliased imports).
3501     fn lookup_candidates<FilterFn>(&mut self,
3502                                    lookup_name: Name,
3503                                    namespace: Namespace,
3504                                    filter_fn: FilterFn) -> SuggestedCandidates
3505         where FilterFn: Fn(Def) -> bool {
3506
3507         let mut lookup_results = Vec::new();
3508         let mut worklist = Vec::new();
3509         worklist.push((self.graph_root, Vec::new(), false));
3510
3511         while let Some((in_module,
3512                         path_segments,
3513                         in_module_is_extern)) = worklist.pop() {
3514             build_reduced_graph::populate_module_if_necessary(self, &in_module);
3515
3516             in_module.for_each_child(|name, ns, name_binding| {
3517
3518                 // avoid imports entirely
3519                 if name_binding.is_import() { return; }
3520
3521                 // collect results based on the filter function
3522                 if let Some(def) = name_binding.def() {
3523                     if name == lookup_name && ns == namespace && filter_fn(def) {
3524                         // create the path
3525                         let ident = hir::Ident::from_name(name);
3526                         let params = PathParameters::none();
3527                         let segment = PathSegment {
3528                             identifier: ident,
3529                             parameters: params,
3530                         };
3531                         let span = name_binding.span.unwrap_or(syntax::codemap::DUMMY_SP);
3532                         let mut segms = path_segments.clone();
3533                         segms.push(segment);
3534                         let segms = HirVec::from_vec(segms);
3535                         let path = Path {
3536                             span: span,
3537                             global: true,
3538                             segments: segms,
3539                         };
3540                         // the entity is accessible in the following cases:
3541                         // 1. if it's defined in the same crate, it's always
3542                         // accessible (since private entities can be made public)
3543                         // 2. if it's defined in another crate, it's accessible
3544                         // only if both the module is public and the entity is
3545                         // declared as public (due to pruning, we don't explore
3546                         // outside crate private modules => no need to check this)
3547                         if !in_module_is_extern || name_binding.is_public() {
3548                             lookup_results.push(path);
3549                         }
3550                     }
3551                 }
3552
3553                 // collect submodules to explore
3554                 if let Some(module) = name_binding.module() {
3555                     // form the path
3556                     let path_segments = match module.parent_link {
3557                         NoParentLink => path_segments.clone(),
3558                         ModuleParentLink(_, name) => {
3559                             let mut paths = path_segments.clone();
3560                             let ident = hir::Ident::from_name(name);
3561                             let params = PathParameters::none();
3562                             let segm = PathSegment {
3563                                 identifier: ident,
3564                                 parameters: params,
3565                             };
3566                             paths.push(segm);
3567                             paths
3568                         }
3569                         _ => unreachable!(),
3570                     };
3571
3572                     if !in_module_is_extern || name_binding.is_public() {
3573                         // add the module to the lookup
3574                         let is_extern = in_module_is_extern || module.is_extern_crate;
3575                         worklist.push((module, path_segments, is_extern));
3576                     }
3577                 }
3578             })
3579         }
3580
3581         SuggestedCandidates {
3582             name: lookup_name.as_str().to_string(),
3583             candidates: lookup_results,
3584         }
3585     }
3586
3587     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3588         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3589         assert!(match resolution.last_private {
3590                     LastImport{..} => false,
3591                     _ => true,
3592                 },
3593                 "Import should only be used for `use` directives");
3594
3595         if let Some(prev_res) = self.def_map.borrow_mut().insert(node_id, resolution) {
3596             let span = self.ast_map.opt_span(node_id).unwrap_or(codemap::DUMMY_SP);
3597             self.session.span_bug(span,
3598                                   &format!("path resolved multiple times ({:?} before, {:?} now)",
3599                                            prev_res,
3600                                            resolution));
3601         }
3602     }
3603
3604     fn enforce_default_binding_mode(&mut self,
3605                                     pat: &Pat,
3606                                     pat_binding_mode: BindingMode,
3607                                     descr: &str) {
3608         match pat_binding_mode {
3609             BindByValue(_) => {}
3610             BindByRef(..) => {
3611                 resolve_error(self,
3612                               pat.span,
3613                               ResolutionError::CannotUseRefBindingModeWith(descr));
3614             }
3615         }
3616     }
3617 }
3618
3619
3620 fn names_to_string(names: &[Name]) -> String {
3621     let mut first = true;
3622     let mut result = String::new();
3623     for name in names {
3624         if first {
3625             first = false
3626         } else {
3627             result.push_str("::")
3628         }
3629         result.push_str(&name.as_str());
3630     }
3631     result
3632 }
3633
3634 fn path_names_to_string(path: &Path, depth: usize) -> String {
3635     let names: Vec<ast::Name> = path.segments[..path.segments.len() - depth]
3636                                     .iter()
3637                                     .map(|seg| seg.identifier.name)
3638                                     .collect();
3639     names_to_string(&names[..])
3640 }
3641
3642 /// When an entity with a given name is not available in scope, we search for
3643 /// entities with that name in all crates. This method allows outputting the
3644 /// results of this search in a programmer-friendly way
3645 fn show_candidates(session: &mut DiagnosticBuilder,
3646                    span: syntax::codemap::Span,
3647                    candidates: &SuggestedCandidates) {
3648
3649     let paths = &candidates.candidates;
3650
3651     if paths.len() > 0 {
3652         // don't show more than MAX_CANDIDATES results, so
3653         // we're consistent with the trait suggestions
3654         const MAX_CANDIDATES: usize = 5;
3655
3656         // we want consistent results across executions, but candidates are produced
3657         // by iterating through a hash map, so make sure they are ordered:
3658         let mut path_strings: Vec<_> = paths.into_iter()
3659                                             .map(|p| path_names_to_string(&p, 0))
3660                                             .collect();
3661         path_strings.sort();
3662
3663         // behave differently based on how many candidates we have:
3664         if !paths.is_empty() {
3665             if paths.len() == 1 {
3666                 session.fileline_help(
3667                     span,
3668                     &format!("you can to import it into scope: `use {};`.",
3669                         &path_strings[0]),
3670                 );
3671             } else {
3672                 session.fileline_help(span, "you can import several candidates \
3673                     into scope (`use ...;`):");
3674                 let count = path_strings.len() as isize - MAX_CANDIDATES as isize + 1;
3675
3676                 for (idx, path_string) in path_strings.iter().enumerate() {
3677                     if idx == MAX_CANDIDATES - 1 && count > 1 {
3678                         session.fileline_help(
3679                             span,
3680                             &format!("  and {} other candidates", count).to_string(),
3681                         );
3682                         break;
3683                     } else {
3684                         session.fileline_help(
3685                             span,
3686                             &format!("  `{}`", path_string).to_string(),
3687                         );
3688                     }
3689                 }
3690             }
3691         }
3692     } else {
3693         // nothing found:
3694         session.fileline_help(
3695             span,
3696             &format!("no candidates by the name of `{}` found in your \
3697             project; maybe you misspelled the name or forgot to import \
3698             an external crate?", candidates.name.to_string()),
3699         );
3700     };
3701 }
3702
3703 /// A somewhat inefficient routine to obtain the name of a module.
3704 fn module_to_string(module: Module) -> String {
3705     let mut names = Vec::new();
3706
3707     fn collect_mod(names: &mut Vec<ast::Name>, module: Module) {
3708         match module.parent_link {
3709             NoParentLink => {}
3710             ModuleParentLink(ref module, name) => {
3711                 names.push(name);
3712                 collect_mod(names, module);
3713             }
3714             BlockParentLink(ref module, _) => {
3715                 // danger, shouldn't be ident?
3716                 names.push(special_idents::opaque.name);
3717                 collect_mod(names, module);
3718             }
3719         }
3720     }
3721     collect_mod(&mut names, module);
3722
3723     if names.is_empty() {
3724         return "???".to_string();
3725     }
3726     names_to_string(&names.into_iter().rev().collect::<Vec<ast::Name>>())
3727 }
3728
3729 fn err_path_resolution() -> PathResolution {
3730     PathResolution {
3731         base_def: Def::Err,
3732         last_private: LastMod(AllPublic),
3733         depth: 0,
3734     }
3735 }
3736
3737
3738 pub struct CrateMap {
3739     pub def_map: RefCell<DefMap>,
3740     pub freevars: FreevarMap,
3741     pub export_map: ExportMap,
3742     pub trait_map: TraitMap,
3743     pub external_exports: ExternalExports,
3744     pub glob_map: Option<GlobMap>,
3745 }
3746
3747 #[derive(PartialEq,Copy, Clone)]
3748 pub enum MakeGlobMap {
3749     Yes,
3750     No,
3751 }
3752
3753 /// Entry point to crate resolution.
3754 pub fn resolve_crate<'a, 'tcx>(session: &'a Session,
3755                                ast_map: &'a hir_map::Map<'tcx>,
3756                                make_glob_map: MakeGlobMap)
3757                                -> CrateMap {
3758     // Currently, we ignore the name resolution data structures for
3759     // the purposes of dependency tracking. Instead we will run name
3760     // resolution and include its output in the hash of each item,
3761     // much like we do for macro expansion. In other words, the hash
3762     // reflects not just its contents but the results of name
3763     // resolution on those contents. Hopefully we'll push this back at
3764     // some point.
3765     let _task = ast_map.dep_graph.in_task(DepNode::Resolve);
3766
3767     let krate = ast_map.krate();
3768     let arenas = Resolver::arenas();
3769     let mut resolver = create_resolver(session, ast_map, krate, make_glob_map, &arenas, None);
3770
3771     resolver.resolve_crate(krate);
3772
3773     check_unused::check_crate(&mut resolver, krate);
3774
3775     CrateMap {
3776         def_map: resolver.def_map,
3777         freevars: resolver.freevars,
3778         export_map: resolver.export_map,
3779         trait_map: resolver.trait_map,
3780         external_exports: resolver.external_exports,
3781         glob_map: if resolver.make_glob_map {
3782             Some(resolver.glob_map)
3783         } else {
3784             None
3785         },
3786     }
3787 }
3788
3789 /// Builds a name resolution walker to be used within this module,
3790 /// or used externally, with an optional callback function.
3791 ///
3792 /// The callback takes a &mut bool which allows callbacks to end a
3793 /// walk when set to true, passing through the rest of the walk, while
3794 /// preserving the ribs + current module. This allows resolve_path
3795 /// calls to be made with the correct scope info. The node in the
3796 /// callback corresponds to the current node in the walk.
3797 pub fn create_resolver<'a, 'tcx>(session: &'a Session,
3798                                  ast_map: &'a hir_map::Map<'tcx>,
3799                                  krate: &'a Crate,
3800                                  make_glob_map: MakeGlobMap,
3801                                  arenas: &'a ResolverArenas<'a>,
3802                                  callback: Option<Box<Fn(hir_map::Node, &mut bool) -> bool>>)
3803                                  -> Resolver<'a, 'tcx> {
3804     let mut resolver = Resolver::new(session, ast_map, make_glob_map, arenas);
3805
3806     resolver.callback = callback;
3807
3808     build_reduced_graph::build_reduced_graph(&mut resolver, krate);
3809
3810     resolve_imports::resolve_imports(&mut resolver);
3811
3812     resolver
3813 }
3814
3815 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }