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 #![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 syntax_pos;
  30 extern crate rustc_errors as errors;
  31 extern crate arena;
  32 #[macro_use]
  33 extern crate rustc;
  34
  35 use self::Namespace::*;
  36 use self::TypeParameters::*;
  37 use self::RibKind::*;
  38
  39 use rustc::hir::map::{Definitions, DefCollector};
  40 use rustc::hir::{self, PrimTy, TyBool, TyChar, TyFloat, TyInt, TyUint, TyStr};
  41 use rustc::middle::cstore::CrateLoader;
  42 use rustc::session::Session;
  43 use rustc::lint;
  44 use rustc::hir::def::*;
  45 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  46 use rustc::ty;
  47 use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
  48 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
  49
  50 use syntax::ext::hygiene::{Mark, SyntaxContext};
  51 use syntax::ast::{self, Name, NodeId, Ident, SpannedIdent, FloatTy, IntTy, UintTy};
  52 use syntax::ext::base::SyntaxExtension;
  53 use syntax::ext::base::Determinacy::{Determined, Undetermined};
  54 use syntax::ext::base::MacroKind;
  55 use syntax::symbol::{Symbol, keywords};
  56 use syntax::util::lev_distance::find_best_match_for_name;
  57
  58 use syntax::visit::{self, FnKind, Visitor};
  59 use syntax::attr;
  60 use syntax::ast::{Arm, BindingMode, Block, Crate, Expr, ExprKind};
  61 use syntax::ast::{FnDecl, ForeignItem, ForeignItemKind, Generics};
  62 use syntax::ast::{Item, ItemKind, ImplItem, ImplItemKind};
  63 use syntax::ast::{Local, Mutability, Pat, PatKind, Path};
  64 use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
  65 use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
  66
  67 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  68 use errors::DiagnosticBuilder;
  69
  70 use std::cell::{Cell, RefCell};
  71 use std::cmp;
  72 use std::collections::BTreeSet;
  73 use std::fmt;
  74 use std::mem::replace;
  75 use std::rc::Rc;
  76
  77 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
  78 use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
  79
  80 // NB: This module needs to be declared first so diagnostics are
  81 // registered before they are used.
  82 mod diagnostics;
  83
  84 mod macros;
  85 mod check_unused;
  86 mod build_reduced_graph;
  87 mod resolve_imports;
  88
  89 /// A free importable items suggested in case of resolution failure.
  90 struct ImportSuggestion {
  91     path: Path,
  92 }
  93
  94 /// A field or associated item from self type suggested in case of resolution failure.
  95 enum AssocSuggestion {
  96     Field,
  97     MethodWithSelf,
  98     AssocItem,
  99 }
 100
 101 #[derive(Eq)]
 102 struct BindingError {
 103     name: Name,
 104     origin: BTreeSet<Span>,
 105     target: BTreeSet<Span>,
 106 }
 107
 108 impl PartialOrd for BindingError {
 109     fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
 110         Some(self.cmp(other))
 111     }
 112 }
 113
 114 impl PartialEq for BindingError {
 115     fn eq(&self, other: &BindingError) -> bool {
 116         self.name == other.name
 117     }
 118 }
 119
 120 impl Ord for BindingError {
 121     fn cmp(&self, other: &BindingError) -> cmp::Ordering {
 122         self.name.cmp(&other.name)
 123     }
 124 }
 125
 126 enum ResolutionError<'a> {
 127     /// error E0401: can't use type parameters from outer function
 128     TypeParametersFromOuterFunction,
 129     /// error E0402: cannot use an outer type parameter in this context
 130     OuterTypeParameterContext,
 131     /// error E0403: the name is already used for a type parameter in this type parameter list
 132     NameAlreadyUsedInTypeParameterList(Name, &'a Span),
 133     /// error E0407: method is not a member of trait
 134     MethodNotMemberOfTrait(Name, &'a str),
 135     /// error E0437: type is not a member of trait
 136     TypeNotMemberOfTrait(Name, &'a str),
 137     /// error E0438: const is not a member of trait
 138     ConstNotMemberOfTrait(Name, &'a str),
 139     /// error E0408: variable `{}` is not bound in all patterns
 140     VariableNotBoundInPattern(&'a BindingError),
 141     /// error E0409: variable `{}` is bound in inconsistent ways within the same match arm
 142     VariableBoundWithDifferentMode(Name, Span),
 143     /// error E0415: identifier is bound more than once in this parameter list
 144     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 145     /// error E0416: identifier is bound more than once in the same pattern
 146     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 147     /// error E0426: use of undeclared label
 148     UndeclaredLabel(&'a str),
 149     /// error E0429: `self` imports are only allowed within a { } list
 150     SelfImportsOnlyAllowedWithin,
 151     /// error E0430: `self` import can only appear once in the list
 152     SelfImportCanOnlyAppearOnceInTheList,
 153     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 154     SelfImportOnlyInImportListWithNonEmptyPrefix,
 155     /// error E0432: unresolved import
 156     UnresolvedImport(Option<(&'a str, &'a str)>),
 157     /// error E0433: failed to resolve
 158     FailedToResolve(&'a str),
 159     /// error E0434: can't capture dynamic environment in a fn item
 160     CannotCaptureDynamicEnvironmentInFnItem,
 161     /// error E0435: attempt to use a non-constant value in a constant
 162     AttemptToUseNonConstantValueInConstant,
 163     /// error E0530: X bindings cannot shadow Ys
 164     BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
 165     /// error E0128: type parameters with a default cannot use forward declared identifiers
 166     ForwardDeclaredTyParam,
 167 }
 168
 169 fn resolve_error<'sess, 'a>(resolver: &'sess Resolver,
 170                             span: Span,
 171                             resolution_error: ResolutionError<'a>) {
 172     resolve_struct_error(resolver, span, resolution_error).emit();
 173 }
 174
 175 fn resolve_struct_error<'sess, 'a>(resolver: &'sess Resolver,
 176                                    span: Span,
 177                                    resolution_error: ResolutionError<'a>)
 178                                    -> DiagnosticBuilder<'sess> {
 179     match resolution_error {
 180         ResolutionError::TypeParametersFromOuterFunction => {
 181             let mut err = struct_span_err!(resolver.session,
 182                                            span,
 183                                            E0401,
 184                                            "can't use type parameters from outer function; \
 185                                            try using a local type parameter instead");
 186             err.span_label(span, &format!("use of type variable from outer function"));
 187             err
 188         }
 189         ResolutionError::OuterTypeParameterContext => {
 190             struct_span_err!(resolver.session,
 191                              span,
 192                              E0402,
 193                              "cannot use an outer type parameter in this context")
 194         }
 195         ResolutionError::NameAlreadyUsedInTypeParameterList(name, first_use_span) => {
 196              let mut err = struct_span_err!(resolver.session,
 197                                             span,
 198                                             E0403,
 199                                             "the name `{}` is already used for a type parameter \
 200                                             in this type parameter list",
 201                                             name);
 202              err.span_label(span, &format!("already used"));
 203              err.span_label(first_use_span.clone(), &format!("first use of `{}`", name));
 204              err
 205         }
 206         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 207             let mut err = struct_span_err!(resolver.session,
 208                                            span,
 209                                            E0407,
 210                                            "method `{}` is not a member of trait `{}`",
 211                                            method,
 212                                            trait_);
 213             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 214             err
 215         }
 216         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 217             let mut err = struct_span_err!(resolver.session,
 218                              span,
 219                              E0437,
 220                              "type `{}` is not a member of trait `{}`",
 221                              type_,
 222                              trait_);
 223             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 224             err
 225         }
 226         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 227             let mut err = struct_span_err!(resolver.session,
 228                              span,
 229                              E0438,
 230                              "const `{}` is not a member of trait `{}`",
 231                              const_,
 232                              trait_);
 233             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 234             err
 235         }
 236         ResolutionError::VariableNotBoundInPattern(binding_error) => {
 237             let target_sp = binding_error.target.iter().map(|x| *x).collect::<Vec<_>>();
 238             let msp = MultiSpan::from_spans(target_sp.clone());
 239             let msg = format!("variable `{}` is not bound in all patterns", binding_error.name);
 240             let mut err = resolver.session.struct_span_err_with_code(msp, &msg, "E0408");
 241             for sp in target_sp {
 242                 err.span_label(sp, &format!("pattern doesn't bind `{}`", binding_error.name));
 243             }
 244             let origin_sp = binding_error.origin.iter().map(|x| *x).collect::<Vec<_>>();
 245             for sp in origin_sp {
 246                 err.span_label(sp, &"variable not in all patterns");
 247             }
 248             err
 249         }
 250         ResolutionError::VariableBoundWithDifferentMode(variable_name,
 251                                                         first_binding_span) => {
 252             let mut err = struct_span_err!(resolver.session,
 253                              span,
 254                              E0409,
 255                              "variable `{}` is bound in inconsistent \
 256                              ways within the same match arm",
 257                              variable_name);
 258             err.span_label(span, &format!("bound in different ways"));
 259             err.span_label(first_binding_span, &format!("first binding"));
 260             err
 261         }
 262         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 263             let mut err = struct_span_err!(resolver.session,
 264                              span,
 265                              E0415,
 266                              "identifier `{}` is bound more than once in this parameter list",
 267                              identifier);
 268             err.span_label(span, &format!("used as parameter more than once"));
 269             err
 270         }
 271         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 272             let mut err = struct_span_err!(resolver.session,
 273                              span,
 274                              E0416,
 275                              "identifier `{}` is bound more than once in the same pattern",
 276                              identifier);
 277             err.span_label(span, &format!("used in a pattern more than once"));
 278             err
 279         }
 280         ResolutionError::UndeclaredLabel(name) => {
 281             let mut err = struct_span_err!(resolver.session,
 282                                            span,
 283                                            E0426,
 284                                            "use of undeclared label `{}`",
 285                                            name);
 286             err.span_label(span, &format!("undeclared label `{}`",&name));
 287             err
 288         }
 289         ResolutionError::SelfImportsOnlyAllowedWithin => {
 290             struct_span_err!(resolver.session,
 291                              span,
 292                              E0429,
 293                              "{}",
 294                              "`self` imports are only allowed within a { } list")
 295         }
 296         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 297             struct_span_err!(resolver.session,
 298                              span,
 299                              E0430,
 300                              "`self` import can only appear once in the list")
 301         }
 302         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 303             struct_span_err!(resolver.session,
 304                              span,
 305                              E0431,
 306                              "`self` import can only appear in an import list with a \
 307                               non-empty prefix")
 308         }
 309         ResolutionError::UnresolvedImport(name) => {
 310             let msg = match name {
 311                 Some((n, _)) => format!("unresolved import `{}`", n),
 312                 None => "unresolved import".to_owned(),
 313             };
 314             let mut err = struct_span_err!(resolver.session, span, E0432, "{}", msg);
 315             if let Some((_, p)) = name {
 316                 err.span_label(span, &p);
 317             }
 318             err
 319         }
 320         ResolutionError::FailedToResolve(msg) => {
 321             let mut err = struct_span_err!(resolver.session, span, E0433,
 322                                            "failed to resolve. {}", msg);
 323             err.span_label(span, &msg);
 324             err
 325         }
 326         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 327             struct_span_err!(resolver.session,
 328                              span,
 329                              E0434,
 330                              "{}",
 331                              "can't capture dynamic environment in a fn item; use the || { ... } \
 332                               closure form instead")
 333         }
 334         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 335             let mut err = struct_span_err!(resolver.session,
 336                              span,
 337                              E0435,
 338                              "attempt to use a non-constant value in a constant");
 339             err.span_label(span, &format!("non-constant used with constant"));
 340             err
 341         }
 342         ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
 343             let shadows_what = PathResolution::new(binding.def()).kind_name();
 344             let mut err = struct_span_err!(resolver.session,
 345                                            span,
 346                                            E0530,
 347                                            "{}s cannot shadow {}s", what_binding, shadows_what);
 348             err.span_label(span, &format!("cannot be named the same as a {}", shadows_what));
 349             let participle = if binding.is_import() { "imported" } else { "defined" };
 350             let msg = &format!("a {} `{}` is {} here", shadows_what, name, participle);
 351             err.span_label(binding.span, msg);
 352             err
 353         }
 354         ResolutionError::ForwardDeclaredTyParam => {
 355             let mut err = struct_span_err!(resolver.session, span, E0128,
 356                                            "type parameters with a default cannot use \
 357                                             forward declared identifiers");
 358             err.span_label(span, &format!("defaulted type parameters \
 359                                            cannot be forward declared"));
 360             err
 361         }
 362     }
 363 }
 364
 365 #[derive(Copy, Clone, Debug)]
 366 struct BindingInfo {
 367     span: Span,
 368     binding_mode: BindingMode,
 369 }
 370
 371 // Map from the name in a pattern to its binding mode.
 372 type BindingMap = FxHashMap<Ident, BindingInfo>;
 373
 374 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 375 enum PatternSource {
 376     Match,
 377     IfLet,
 378     WhileLet,
 379     Let,
 380     For,
 381     FnParam,
 382 }
 383
 384 impl PatternSource {
 385     fn is_refutable(self) -> bool {
 386         match self {
 387             PatternSource::Match | PatternSource::IfLet | PatternSource::WhileLet => true,
 388             PatternSource::Let | PatternSource::For | PatternSource::FnParam  => false,
 389         }
 390     }
 391     fn descr(self) -> &'static str {
 392         match self {
 393             PatternSource::Match => "match binding",
 394             PatternSource::IfLet => "if let binding",
 395             PatternSource::WhileLet => "while let binding",
 396             PatternSource::Let => "let binding",
 397             PatternSource::For => "for binding",
 398             PatternSource::FnParam => "function parameter",
 399         }
 400     }
 401 }
 402
 403 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 404 enum PathSource<'a> {
 405     // Type paths `Path`.
 406     Type,
 407     // Trait paths in bounds or impls.
 408     Trait,
 409     // Expression paths `path`, with optional parent context.
 410     Expr(Option<&'a Expr>),
 411     // Paths in path patterns `Path`.
 412     Pat,
 413     // Paths in struct expressions and patterns `Path { .. }`.
 414     Struct,
 415     // Paths in tuple struct patterns `Path(..)`.
 416     TupleStruct,
 417     // `m::A::B` in `<T as m::A>::B::C`.
 418     TraitItem(Namespace),
 419     // Path in `pub(path)`
 420     Visibility,
 421     // Path in `use a::b::{...};`
 422     ImportPrefix,
 423 }
 424
 425 impl<'a> PathSource<'a> {
 426     fn namespace(self) -> Namespace {
 427         match self {
 428             PathSource::Type | PathSource::Trait | PathSource::Struct |
 429             PathSource::Visibility | PathSource::ImportPrefix => TypeNS,
 430             PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
 431             PathSource::TraitItem(ns) => ns,
 432         }
 433     }
 434
 435     fn global_by_default(self) -> bool {
 436         match self {
 437             PathSource::Visibility | PathSource::ImportPrefix => true,
 438             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 439             PathSource::Struct | PathSource::TupleStruct |
 440             PathSource::Trait | PathSource::TraitItem(..) => false,
 441         }
 442     }
 443
 444     fn defer_to_typeck(self) -> bool {
 445         match self {
 446             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 447             PathSource::Struct | PathSource::TupleStruct => true,
 448             PathSource::Trait | PathSource::TraitItem(..) |
 449             PathSource::Visibility | PathSource::ImportPrefix => false,
 450         }
 451     }
 452
 453     fn descr_expected(self) -> &'static str {
 454         match self {
 455             PathSource::Type => "type",
 456             PathSource::Trait => "trait",
 457             PathSource::Pat => "unit struct/variant or constant",
 458             PathSource::Struct => "struct, variant or union type",
 459             PathSource::TupleStruct => "tuple struct/variant",
 460             PathSource::Visibility => "module",
 461             PathSource::ImportPrefix => "module or enum",
 462             PathSource::TraitItem(ns) => match ns {
 463                 TypeNS => "associated type",
 464                 ValueNS => "method or associated constant",
 465                 MacroNS => bug!("associated macro"),
 466             },
 467             PathSource::Expr(parent) => match parent.map(|p| &p.node) {
 468                 // "function" here means "anything callable" rather than `Def::Fn`,
 469                 // this is not precise but usually more helpful than just "value".
 470                 Some(&ExprKind::Call(..)) => "function",
 471                 _ => "value",
 472             },
 473         }
 474     }
 475
 476     fn is_expected(self, def: Def) -> bool {
 477         match self {
 478             PathSource::Type => match def {
 479                 Def::Struct(..) | Def::Union(..) | Def::Enum(..) |
 480                 Def::Trait(..) | Def::TyAlias(..) | Def::AssociatedTy(..) |
 481                 Def::PrimTy(..) | Def::TyParam(..) | Def::SelfTy(..) => true,
 482                 _ => false,
 483             },
 484             PathSource::Trait => match def {
 485                 Def::Trait(..) => true,
 486                 _ => false,
 487             },
 488             PathSource::Expr(..) => match def {
 489                 Def::StructCtor(_, CtorKind::Const) | Def::StructCtor(_, CtorKind::Fn) |
 490                 Def::VariantCtor(_, CtorKind::Const) | Def::VariantCtor(_, CtorKind::Fn) |
 491                 Def::Const(..) | Def::Static(..) | Def::Local(..) | Def::Upvar(..) |
 492                 Def::Fn(..) | Def::Method(..) | Def::AssociatedConst(..) => true,
 493                 _ => false,
 494             },
 495             PathSource::Pat => match def {
 496                 Def::StructCtor(_, CtorKind::Const) |
 497                 Def::VariantCtor(_, CtorKind::Const) |
 498                 Def::Const(..) | Def::AssociatedConst(..) => true,
 499                 _ => false,
 500             },
 501             PathSource::TupleStruct => match def {
 502                 Def::StructCtor(_, CtorKind::Fn) | Def::VariantCtor(_, CtorKind::Fn) => true,
 503                 _ => false,
 504             },
 505             PathSource::Struct => match def {
 506                 Def::Struct(..) | Def::Union(..) | Def::Variant(..) |
 507                 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => true,
 508                 _ => false,
 509             },
 510             PathSource::TraitItem(ns) => match def {
 511                 Def::AssociatedConst(..) | Def::Method(..) if ns == ValueNS => true,
 512                 Def::AssociatedTy(..) if ns == TypeNS => true,
 513                 _ => false,
 514             },
 515             PathSource::ImportPrefix => match def {
 516                 Def::Mod(..) | Def::Enum(..) => true,
 517                 _ => false,
 518             },
 519             PathSource::Visibility => match def {
 520                 Def::Mod(..) => true,
 521                 _ => false,
 522             },
 523         }
 524     }
 525
 526     fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
 527         __diagnostic_used!(E0404);
 528         __diagnostic_used!(E0405);
 529         __diagnostic_used!(E0412);
 530         __diagnostic_used!(E0422);
 531         __diagnostic_used!(E0423);
 532         __diagnostic_used!(E0425);
 533         __diagnostic_used!(E0531);
 534         __diagnostic_used!(E0532);
 535         __diagnostic_used!(E0573);
 536         __diagnostic_used!(E0574);
 537         __diagnostic_used!(E0575);
 538         __diagnostic_used!(E0576);
 539         __diagnostic_used!(E0577);
 540         __diagnostic_used!(E0578);
 541         match (self, has_unexpected_resolution) {
 542             (PathSource::Trait, true) => "E0404",
 543             (PathSource::Trait, false) => "E0405",
 544             (PathSource::Type, true) => "E0573",
 545             (PathSource::Type, false) => "E0412",
 546             (PathSource::Struct, true) => "E0574",
 547             (PathSource::Struct, false) => "E0422",
 548             (PathSource::Expr(..), true) => "E0423",
 549             (PathSource::Expr(..), false) => "E0425",
 550             (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
 551             (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
 552             (PathSource::TraitItem(..), true) => "E0575",
 553             (PathSource::TraitItem(..), false) => "E0576",
 554             (PathSource::Visibility, true) | (PathSource::ImportPrefix, true) => "E0577",
 555             (PathSource::Visibility, false) | (PathSource::ImportPrefix, false) => "E0578",
 556         }
 557     }
 558 }
 559
 560 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 561 pub enum Namespace {
 562     TypeNS,
 563     ValueNS,
 564     MacroNS,
 565 }
 566
 567 #[derive(Clone, Default, Debug)]
 568 pub struct PerNS<T> {
 569     value_ns: T,
 570     type_ns: T,
 571     macro_ns: Option<T>,
 572 }
 573
 574 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
 575     type Output = T;
 576     fn index(&self, ns: Namespace) -> &T {
 577         match ns {
 578             ValueNS => &self.value_ns,
 579             TypeNS => &self.type_ns,
 580             MacroNS => self.macro_ns.as_ref().unwrap(),
 581         }
 582     }
 583 }
 584
 585 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
 586     fn index_mut(&mut self, ns: Namespace) -> &mut T {
 587         match ns {
 588             ValueNS => &mut self.value_ns,
 589             TypeNS => &mut self.type_ns,
 590             MacroNS => self.macro_ns.as_mut().unwrap(),
 591         }
 592     }
 593 }
 594
 595 impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
 596     fn visit_item(&mut self, item: &'tcx Item) {
 597         self.resolve_item(item);
 598     }
 599     fn visit_arm(&mut self, arm: &'tcx Arm) {
 600         self.resolve_arm(arm);
 601     }
 602     fn visit_block(&mut self, block: &'tcx Block) {
 603         self.resolve_block(block);
 604     }
 605     fn visit_expr(&mut self, expr: &'tcx Expr) {
 606         self.resolve_expr(expr, None);
 607     }
 608     fn visit_local(&mut self, local: &'tcx Local) {
 609         self.resolve_local(local);
 610     }
 611     fn visit_ty(&mut self, ty: &'tcx Ty) {
 612         if let TyKind::Path(ref qself, ref path) = ty.node {
 613             self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
 614         } else if let TyKind::ImplicitSelf = ty.node {
 615             let self_ty = keywords::SelfType.ident();
 616             let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.span))
 617                           .map_or(Def::Err, |d| d.def());
 618             self.record_def(ty.id, PathResolution::new(def));
 619         } else if let TyKind::Array(ref element, ref length) = ty.node {
 620             self.visit_ty(element);
 621             self.with_constant_rib(|this| {
 622                 this.visit_expr(length);
 623             });
 624             return;
 625         }
 626         visit::walk_ty(self, ty);
 627     }
 628     fn visit_poly_trait_ref(&mut self,
 629                             tref: &'tcx ast::PolyTraitRef,
 630                             m: &'tcx ast::TraitBoundModifier) {
 631         self.smart_resolve_path(tref.trait_ref.ref_id, None,
 632                                 &tref.trait_ref.path, PathSource::Trait);
 633         visit::walk_poly_trait_ref(self, tref, m);
 634     }
 635     fn visit_variant(&mut self,
 636                      variant: &'tcx ast::Variant,
 637                      generics: &'tcx Generics,
 638                      item_id: ast::NodeId) {
 639         if let Some(ref dis_expr) = variant.node.disr_expr {
 640             // resolve the discriminator expr as a constant
 641             self.with_constant_rib(|this| {
 642                 this.visit_expr(dis_expr);
 643             });
 644         }
 645
 646         // `visit::walk_variant` without the discriminant expression.
 647         self.visit_variant_data(&variant.node.data,
 648                                 variant.node.name,
 649                                 generics,
 650                                 item_id,
 651                                 variant.span);
 652     }
 653     fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
 654         let type_parameters = match foreign_item.node {
 655             ForeignItemKind::Fn(_, ref generics) => {
 656                 HasTypeParameters(generics, ItemRibKind)
 657             }
 658             ForeignItemKind::Static(..) => NoTypeParameters,
 659         };
 660         self.with_type_parameter_rib(type_parameters, |this| {
 661             visit::walk_foreign_item(this, foreign_item);
 662         });
 663     }
 664     fn visit_fn(&mut self,
 665                 function_kind: FnKind<'tcx>,
 666                 declaration: &'tcx FnDecl,
 667                 _: Span,
 668                 node_id: NodeId) {
 669         let rib_kind = match function_kind {
 670             FnKind::ItemFn(_, generics, ..) => {
 671                 self.visit_generics(generics);
 672                 ItemRibKind
 673             }
 674             FnKind::Method(_, sig, _, _) => {
 675                 self.visit_generics(&sig.generics);
 676                 MethodRibKind(!sig.decl.has_self())
 677             }
 678             FnKind::Closure(_) => ClosureRibKind(node_id),
 679         };
 680
 681         // Create a value rib for the function.
 682         self.ribs[ValueNS].push(Rib::new(rib_kind));
 683
 684         // Create a label rib for the function.
 685         self.label_ribs.push(Rib::new(rib_kind));
 686
 687         // Add each argument to the rib.
 688         let mut bindings_list = FxHashMap();
 689         for argument in &declaration.inputs {
 690             self.resolve_pattern(&argument.pat, PatternSource::FnParam, &mut bindings_list);
 691
 692             self.visit_ty(&argument.ty);
 693
 694             debug!("(resolving function) recorded argument");
 695         }
 696         visit::walk_fn_ret_ty(self, &declaration.output);
 697
 698         // Resolve the function body.
 699         match function_kind {
 700             FnKind::ItemFn(.., body) |
 701             FnKind::Method(.., body) => {
 702                 self.visit_block(body);
 703             }
 704             FnKind::Closure(body) => {
 705                 self.visit_expr(body);
 706             }
 707         };
 708
 709         debug!("(resolving function) leaving function");
 710
 711         self.label_ribs.pop();
 712         self.ribs[ValueNS].pop();
 713     }
 714     fn visit_generics(&mut self, generics: &'tcx Generics) {
 715         // For type parameter defaults, we have to ban access
 716         // to following type parameters, as the Substs can only
 717         // provide previous type parameters as they're built.
 718         let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
 719         default_ban_rib.bindings.extend(generics.ty_params.iter()
 720             .skip_while(|p| p.default.is_none())
 721             .map(|p| (Ident::with_empty_ctxt(p.ident.name), Def::Err)));
 722
 723         for param in &generics.ty_params {
 724             for bound in &param.bounds {
 725                 self.visit_ty_param_bound(bound);
 726             }
 727
 728             if let Some(ref ty) = param.default {
 729                 self.ribs[TypeNS].push(default_ban_rib);
 730                 self.visit_ty(ty);
 731                 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
 732             }
 733
 734             // Allow all following defaults to refer to this type parameter.
 735             default_ban_rib.bindings.remove(&Ident::with_empty_ctxt(param.ident.name));
 736         }
 737         for lt in &generics.lifetimes { self.visit_lifetime_def(lt); }
 738         for p in &generics.where_clause.predicates { self.visit_where_predicate(p); }
 739     }
 740 }
 741
 742 pub type ErrorMessage = Option<(Span, String)>;
 743
 744 #[derive(Copy, Clone)]
 745 enum TypeParameters<'a, 'b> {
 746     NoTypeParameters,
 747     HasTypeParameters(// Type parameters.
 748                       &'b Generics,
 749
 750                       // The kind of the rib used for type parameters.
 751                       RibKind<'a>),
 752 }
 753
 754 // The rib kind controls the translation of local
 755 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 756 #[derive(Copy, Clone, Debug)]
 757 enum RibKind<'a> {
 758     // No translation needs to be applied.
 759     NormalRibKind,
 760
 761     // We passed through a closure scope at the given node ID.
 762     // Translate upvars as appropriate.
 763     ClosureRibKind(NodeId /* func id */),
 764
 765     // We passed through an impl or trait and are now in one of its
 766     // methods. Allow references to ty params that impl or trait
 767     // binds. Disallow any other upvars (including other ty params that are
 768     // upvars).
 769     //
 770     // The boolean value represents the fact that this method is static or not.
 771     MethodRibKind(bool),
 772
 773     // We passed through an item scope. Disallow upvars.
 774     ItemRibKind,
 775
 776     // We're in a constant item. Can't refer to dynamic stuff.
 777     ConstantItemRibKind,
 778
 779     // We passed through a module.
 780     ModuleRibKind(Module<'a>),
 781
 782     // We passed through a `macro_rules!` statement
 783     MacroDefinition(DefId),
 784
 785     // All bindings in this rib are type parameters that can't be used
 786     // from the default of a type parameter because they're not declared
 787     // before said type parameter. Also see the `visit_generics` override.
 788     ForwardTyParamBanRibKind,
 789 }
 790
 791 /// One local scope.
 792 #[derive(Debug)]
 793 struct Rib<'a> {
 794     bindings: FxHashMap<Ident, Def>,
 795     kind: RibKind<'a>,
 796 }
 797
 798 impl<'a> Rib<'a> {
 799     fn new(kind: RibKind<'a>) -> Rib<'a> {
 800         Rib {
 801             bindings: FxHashMap(),
 802             kind: kind,
 803         }
 804     }
 805 }
 806
 807 enum LexicalScopeBinding<'a> {
 808     Item(&'a NameBinding<'a>),
 809     Def(Def),
 810 }
 811
 812 impl<'a> LexicalScopeBinding<'a> {
 813     fn item(self) -> Option<&'a NameBinding<'a>> {
 814         match self {
 815             LexicalScopeBinding::Item(binding) => Some(binding),
 816             _ => None,
 817         }
 818     }
 819
 820     fn def(self) -> Def {
 821         match self {
 822             LexicalScopeBinding::Item(binding) => binding.def(),
 823             LexicalScopeBinding::Def(def) => def,
 824         }
 825     }
 826 }
 827
 828 #[derive(Clone)]
 829 enum PathResult<'a> {
 830     Module(Module<'a>),
 831     NonModule(PathResolution),
 832     Indeterminate,
 833     Failed(String, bool /* is the error from the last segment? */),
 834 }
 835
 836 enum ModuleKind {
 837     Block(NodeId),
 838     Def(Def, Name),
 839 }
 840
 841 /// One node in the tree of modules.
 842 pub struct ModuleData<'a> {
 843     parent: Option<Module<'a>>,
 844     kind: ModuleKind,
 845
 846     // The def id of the closest normal module (`mod`) ancestor (including this module).
 847     normal_ancestor_id: DefId,
 848
 849     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
 850     legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, Span, MacroKind)>>,
 851     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 852
 853     // Macro invocations that can expand into items in this module.
 854     unresolved_invocations: RefCell<FxHashSet<Mark>>,
 855
 856     no_implicit_prelude: bool,
 857
 858     glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
 859     globs: RefCell<Vec<&'a ImportDirective<'a>>>,
 860
 861     // Used to memoize the traits in this module for faster searches through all traits in scope.
 862     traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
 863
 864     // Whether this module is populated. If not populated, any attempt to
 865     // access the children must be preceded with a
 866     // `populate_module_if_necessary` call.
 867     populated: Cell<bool>,
 868 }
 869
 870 pub type Module<'a> = &'a ModuleData<'a>;
 871
 872 impl<'a> ModuleData<'a> {
 873     fn new(parent: Option<Module<'a>>, kind: ModuleKind, normal_ancestor_id: DefId) -> Self {
 874         ModuleData {
 875             parent: parent,
 876             kind: kind,
 877             normal_ancestor_id: normal_ancestor_id,
 878             resolutions: RefCell::new(FxHashMap()),
 879             legacy_macro_resolutions: RefCell::new(Vec::new()),
 880             macro_resolutions: RefCell::new(Vec::new()),
 881             unresolved_invocations: RefCell::new(FxHashSet()),
 882             no_implicit_prelude: false,
 883             glob_importers: RefCell::new(Vec::new()),
 884             globs: RefCell::new((Vec::new())),
 885             traits: RefCell::new(None),
 886             populated: Cell::new(normal_ancestor_id.is_local()),
 887         }
 888     }
 889
 890     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 891         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 892             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 893         }
 894     }
 895
 896     fn def(&self) -> Option<Def> {
 897         match self.kind {
 898             ModuleKind::Def(def, _) => Some(def),
 899             _ => None,
 900         }
 901     }
 902
 903     fn def_id(&self) -> Option<DefId> {
 904         self.def().as_ref().map(Def::def_id)
 905     }
 906
 907     // `self` resolves to the first module ancestor that `is_normal`.
 908     fn is_normal(&self) -> bool {
 909         match self.kind {
 910             ModuleKind::Def(Def::Mod(_), _) => true,
 911             _ => false,
 912         }
 913     }
 914
 915     fn is_trait(&self) -> bool {
 916         match self.kind {
 917             ModuleKind::Def(Def::Trait(_), _) => true,
 918             _ => false,
 919         }
 920     }
 921
 922     fn is_local(&self) -> bool {
 923         self.normal_ancestor_id.is_local()
 924     }
 925
 926     fn nearest_item_scope(&'a self) -> Module<'a> {
 927         if self.is_trait() { self.parent.unwrap() } else { self }
 928     }
 929 }
 930
 931 impl<'a> fmt::Debug for ModuleData<'a> {
 932     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 933         write!(f, "{:?}", self.def())
 934     }
 935 }
 936
 937 // Records a possibly-private value, type, or module definition.
 938 #[derive(Clone, Debug)]
 939 pub struct NameBinding<'a> {
 940     kind: NameBindingKind<'a>,
 941     expansion: Mark,
 942     span: Span,
 943     vis: ty::Visibility,
 944 }
 945
 946 pub trait ToNameBinding<'a> {
 947     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 948 }
 949
 950 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 951     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 952         self
 953     }
 954 }
 955
 956 #[derive(Clone, Debug)]
 957 enum NameBindingKind<'a> {
 958     Def(Def),
 959     Module(Module<'a>),
 960     Import {
 961         binding: &'a NameBinding<'a>,
 962         directive: &'a ImportDirective<'a>,
 963         used: Cell<bool>,
 964         legacy_self_import: bool,
 965     },
 966     Ambiguity {
 967         b1: &'a NameBinding<'a>,
 968         b2: &'a NameBinding<'a>,
 969         legacy: bool,
 970     }
 971 }
 972
 973 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 974
 975 struct AmbiguityError<'a> {
 976     span: Span,
 977     name: Name,
 978     lexical: bool,
 979     b1: &'a NameBinding<'a>,
 980     b2: &'a NameBinding<'a>,
 981     legacy: bool,
 982 }
 983
 984 impl<'a> NameBinding<'a> {
 985     fn module(&self) -> Option<Module<'a>> {
 986         match self.kind {
 987             NameBindingKind::Module(module) => Some(module),
 988             NameBindingKind::Import { binding, .. } => binding.module(),
 989             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 990             _ => None,
 991         }
 992     }
 993
 994     fn def(&self) -> Def {
 995         match self.kind {
 996             NameBindingKind::Def(def) => def,
 997             NameBindingKind::Module(module) => module.def().unwrap(),
 998             NameBindingKind::Import { binding, .. } => binding.def(),
 999             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1000             NameBindingKind::Ambiguity { .. } => Def::Err,
1001         }
1002     }
1003
1004     fn def_ignoring_ambiguity(&self) -> Def {
1005         match self.kind {
1006             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1007             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1008             _ => self.def(),
1009         }
1010     }
1011
1012     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1013         resolver.get_macro(self.def_ignoring_ambiguity())
1014     }
1015
1016     // We sometimes need to treat variants as `pub` for backwards compatibility
1017     fn pseudo_vis(&self) -> ty::Visibility {
1018         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1019     }
1020
1021     fn is_variant(&self) -> bool {
1022         match self.kind {
1023             NameBindingKind::Def(Def::Variant(..)) |
1024             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1025             _ => false,
1026         }
1027     }
1028
1029     fn is_extern_crate(&self) -> bool {
1030         match self.kind {
1031             NameBindingKind::Import {
1032                 directive: &ImportDirective {
1033                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1034                 }, ..
1035             } => true,
1036             _ => false,
1037         }
1038     }
1039
1040     fn is_import(&self) -> bool {
1041         match self.kind {
1042             NameBindingKind::Import { .. } => true,
1043             _ => false,
1044         }
1045     }
1046
1047     fn is_glob_import(&self) -> bool {
1048         match self.kind {
1049             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1050             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1051             _ => false,
1052         }
1053     }
1054
1055     fn is_importable(&self) -> bool {
1056         match self.def() {
1057             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1058             _ => true,
1059         }
1060     }
1061 }
1062
1063 /// Interns the names of the primitive types.
1064 struct PrimitiveTypeTable {
1065     primitive_types: FxHashMap<Name, PrimTy>,
1066 }
1067
1068 impl PrimitiveTypeTable {
1069     fn new() -> PrimitiveTypeTable {
1070         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1071
1072         table.intern("bool", TyBool);
1073         table.intern("char", TyChar);
1074         table.intern("f32", TyFloat(FloatTy::F32));
1075         table.intern("f64", TyFloat(FloatTy::F64));
1076         table.intern("isize", TyInt(IntTy::Is));
1077         table.intern("i8", TyInt(IntTy::I8));
1078         table.intern("i16", TyInt(IntTy::I16));
1079         table.intern("i32", TyInt(IntTy::I32));
1080         table.intern("i64", TyInt(IntTy::I64));
1081         table.intern("i128", TyInt(IntTy::I128));
1082         table.intern("str", TyStr);
1083         table.intern("usize", TyUint(UintTy::Us));
1084         table.intern("u8", TyUint(UintTy::U8));
1085         table.intern("u16", TyUint(UintTy::U16));
1086         table.intern("u32", TyUint(UintTy::U32));
1087         table.intern("u64", TyUint(UintTy::U64));
1088         table.intern("u128", TyUint(UintTy::U128));
1089         table
1090     }
1091
1092     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1093         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1094     }
1095 }
1096
1097 /// The main resolver class.
1098 pub struct Resolver<'a> {
1099     session: &'a Session,
1100
1101     pub definitions: Definitions,
1102
1103     graph_root: Module<'a>,
1104
1105     prelude: Option<Module<'a>>,
1106
1107     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1108
1109     // Names of fields of an item `DefId` accessible with dot syntax.
1110     // Used for hints during error reporting.
1111     field_names: FxHashMap<DefId, Vec<Name>>,
1112
1113     // All imports known to succeed or fail.
1114     determined_imports: Vec<&'a ImportDirective<'a>>,
1115
1116     // All non-determined imports.
1117     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1118
1119     // The module that represents the current item scope.
1120     current_module: Module<'a>,
1121
1122     // The current set of local scopes for types and values.
1123     // FIXME #4948: Reuse ribs to avoid allocation.
1124     ribs: PerNS<Vec<Rib<'a>>>,
1125
1126     // The current set of local scopes, for labels.
1127     label_ribs: Vec<Rib<'a>>,
1128
1129     // The trait that the current context can refer to.
1130     current_trait_ref: Option<(DefId, TraitRef)>,
1131
1132     // The current self type if inside an impl (used for better errors).
1133     current_self_type: Option<Ty>,
1134
1135     // The idents for the primitive types.
1136     primitive_type_table: PrimitiveTypeTable,
1137
1138     def_map: DefMap,
1139     pub freevars: FreevarMap,
1140     freevars_seen: NodeMap<NodeMap<usize>>,
1141     pub export_map: ExportMap,
1142     pub trait_map: TraitMap,
1143
1144     // A map from nodes to anonymous modules.
1145     // Anonymous modules are pseudo-modules that are implicitly created around items
1146     // contained within blocks.
1147     //
1148     // For example, if we have this:
1149     //
1150     //  fn f() {
1151     //      fn g() {
1152     //          ...
1153     //      }
1154     //  }
1155     //
1156     // There will be an anonymous module created around `g` with the ID of the
1157     // entry block for `f`.
1158     block_map: NodeMap<Module<'a>>,
1159     module_map: FxHashMap<DefId, Module<'a>>,
1160     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1161
1162     pub make_glob_map: bool,
1163     // Maps imports to the names of items actually imported (this actually maps
1164     // all imports, but only glob imports are actually interesting).
1165     pub glob_map: GlobMap,
1166
1167     used_imports: FxHashSet<(NodeId, Namespace)>,
1168     pub maybe_unused_trait_imports: NodeSet,
1169
1170     privacy_errors: Vec<PrivacyError<'a>>,
1171     ambiguity_errors: Vec<AmbiguityError<'a>>,
1172     gated_errors: FxHashSet<Span>,
1173     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1174
1175     arenas: &'a ResolverArenas<'a>,
1176     dummy_binding: &'a NameBinding<'a>,
1177     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1178
1179     crate_loader: &'a mut CrateLoader,
1180     macro_names: FxHashSet<Name>,
1181     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1182     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1183     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1184     macro_defs: FxHashMap<Mark, DefId>,
1185     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1186     macro_exports: Vec<Export>,
1187     pub whitelisted_legacy_custom_derives: Vec<Name>,
1188     pub found_unresolved_macro: bool,
1189
1190     // Maps the `Mark` of an expansion to its containing module or block.
1191     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1192
1193     // Avoid duplicated errors for "name already defined".
1194     name_already_seen: FxHashMap<Name, Span>,
1195
1196     // If `#![feature(proc_macro)]` is set
1197     proc_macro_enabled: bool,
1198
1199     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1200     warned_proc_macros: FxHashSet<Name>,
1201
1202     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1203
1204     // This table maps struct IDs into struct constructor IDs,
1205     // it's not used during normal resolution, only for better error reporting.
1206     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1207 }
1208
1209 pub struct ResolverArenas<'a> {
1210     modules: arena::TypedArena<ModuleData<'a>>,
1211     local_modules: RefCell<Vec<Module<'a>>>,
1212     name_bindings: arena::TypedArena<NameBinding<'a>>,
1213     import_directives: arena::TypedArena<ImportDirective<'a>>,
1214     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1215     invocation_data: arena::TypedArena<InvocationData<'a>>,
1216     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1217 }
1218
1219 impl<'a> ResolverArenas<'a> {
1220     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1221         let module = self.modules.alloc(module);
1222         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1223             self.local_modules.borrow_mut().push(module);
1224         }
1225         module
1226     }
1227     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1228         self.local_modules.borrow()
1229     }
1230     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1231         self.name_bindings.alloc(name_binding)
1232     }
1233     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1234                               -> &'a ImportDirective {
1235         self.import_directives.alloc(import_directive)
1236     }
1237     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1238         self.name_resolutions.alloc(Default::default())
1239     }
1240     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1241                              -> &'a InvocationData<'a> {
1242         self.invocation_data.alloc(expansion_data)
1243     }
1244     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1245         self.legacy_bindings.alloc(binding)
1246     }
1247 }
1248
1249 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1250     fn parent(self, id: DefId) -> Option<DefId> {
1251         match id.krate {
1252             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1253             _ => self.session.cstore.def_key(id).parent,
1254         }.map(|index| DefId { index: index, ..id })
1255     }
1256 }
1257
1258 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1259     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1260         let namespace = if is_value { ValueNS } else { TypeNS };
1261         let hir::Path { ref segments, span, ref mut def } = *path;
1262         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1263         match self.resolve_path(&path, Some(namespace), Some(span)) {
1264             PathResult::Module(module) => *def = module.def().unwrap(),
1265             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1266                 *def = path_res.base_def(),
1267             PathResult::NonModule(..) => match self.resolve_path(&path, None, Some(span)) {
1268                 PathResult::Failed(msg, _) => {
1269                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1270                 }
1271                 _ => {}
1272             },
1273             PathResult::Indeterminate => unreachable!(),
1274             PathResult::Failed(msg, _) => {
1275                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1276             }
1277         }
1278     }
1279
1280     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1281         self.def_map.get(&id).cloned()
1282     }
1283
1284     fn definitions(&mut self) -> &mut Definitions {
1285         &mut self.definitions
1286     }
1287 }
1288
1289 impl<'a> Resolver<'a> {
1290     pub fn new(session: &'a Session,
1291                krate: &Crate,
1292                crate_name: &str,
1293                make_glob_map: MakeGlobMap,
1294                crate_loader: &'a mut CrateLoader,
1295                arenas: &'a ResolverArenas<'a>)
1296                -> Resolver<'a> {
1297         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1298         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1299         let graph_root = arenas.alloc_module(ModuleData {
1300             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1301             ..ModuleData::new(None, root_module_kind, root_def_id)
1302         });
1303         let mut module_map = FxHashMap();
1304         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1305
1306         let mut definitions = Definitions::new();
1307         DefCollector::new(&mut definitions)
1308             .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
1309
1310         let mut invocations = FxHashMap();
1311         invocations.insert(Mark::root(),
1312                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1313
1314         let features = session.features.borrow();
1315
1316         let mut macro_defs = FxHashMap();
1317         macro_defs.insert(Mark::root(), root_def_id);
1318
1319         Resolver {
1320             session: session,
1321
1322             definitions: definitions,
1323
1324             // The outermost module has def ID 0; this is not reflected in the
1325             // AST.
1326             graph_root: graph_root,
1327             prelude: None,
1328
1329             trait_item_map: FxHashMap(),
1330             field_names: FxHashMap(),
1331
1332             determined_imports: Vec::new(),
1333             indeterminate_imports: Vec::new(),
1334
1335             current_module: graph_root,
1336             ribs: PerNS {
1337                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1338                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1339                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1340             },
1341             label_ribs: Vec::new(),
1342
1343             current_trait_ref: None,
1344             current_self_type: None,
1345
1346             primitive_type_table: PrimitiveTypeTable::new(),
1347
1348             def_map: NodeMap(),
1349             freevars: NodeMap(),
1350             freevars_seen: NodeMap(),
1351             export_map: NodeMap(),
1352             trait_map: NodeMap(),
1353             module_map: module_map,
1354             block_map: NodeMap(),
1355             extern_crate_roots: FxHashMap(),
1356
1357             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1358             glob_map: NodeMap(),
1359
1360             used_imports: FxHashSet(),
1361             maybe_unused_trait_imports: NodeSet(),
1362
1363             privacy_errors: Vec::new(),
1364             ambiguity_errors: Vec::new(),
1365             gated_errors: FxHashSet(),
1366             disallowed_shadowing: Vec::new(),
1367
1368             arenas: arenas,
1369             dummy_binding: arenas.alloc_name_binding(NameBinding {
1370                 kind: NameBindingKind::Def(Def::Err),
1371                 expansion: Mark::root(),
1372                 span: DUMMY_SP,
1373                 vis: ty::Visibility::Public,
1374             }),
1375
1376             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1377             use_extern_macros: features.use_extern_macros || features.proc_macro,
1378
1379             crate_loader: crate_loader,
1380             macro_names: FxHashSet(),
1381             global_macros: FxHashMap(),
1382             lexical_macro_resolutions: Vec::new(),
1383             macro_map: FxHashMap(),
1384             macro_exports: Vec::new(),
1385             invocations: invocations,
1386             macro_defs: macro_defs,
1387             local_macro_def_scopes: FxHashMap(),
1388             name_already_seen: FxHashMap(),
1389             whitelisted_legacy_custom_derives: Vec::new(),
1390             proc_macro_enabled: features.proc_macro,
1391             warned_proc_macros: FxHashSet(),
1392             potentially_unused_imports: Vec::new(),
1393             struct_constructors: DefIdMap(),
1394             found_unresolved_macro: false,
1395         }
1396     }
1397
1398     pub fn arenas() -> ResolverArenas<'a> {
1399         ResolverArenas {
1400             modules: arena::TypedArena::new(),
1401             local_modules: RefCell::new(Vec::new()),
1402             name_bindings: arena::TypedArena::new(),
1403             import_directives: arena::TypedArena::new(),
1404             name_resolutions: arena::TypedArena::new(),
1405             invocation_data: arena::TypedArena::new(),
1406             legacy_bindings: arena::TypedArena::new(),
1407         }
1408     }
1409
1410     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1411         PerNS {
1412             type_ns: f(self, TypeNS),
1413             value_ns: f(self, ValueNS),
1414             macro_ns: match self.use_extern_macros {
1415                 true => Some(f(self, MacroNS)),
1416                 false => None,
1417             },
1418         }
1419     }
1420
1421     /// Entry point to crate resolution.
1422     pub fn resolve_crate(&mut self, krate: &Crate) {
1423         ImportResolver { resolver: self }.finalize_imports();
1424         self.current_module = self.graph_root;
1425         self.finalize_current_module_macro_resolutions();
1426         visit::walk_crate(self, krate);
1427
1428         check_unused::check_crate(self, krate);
1429         self.report_errors();
1430         self.crate_loader.postprocess(krate);
1431     }
1432
1433     fn new_module(&self, parent: Module<'a>, kind: ModuleKind, normal_ancestor_id: DefId)
1434                   -> Module<'a> {
1435         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id))
1436     }
1437
1438     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1439                   -> bool /* true if an error was reported */ {
1440         match binding.kind {
1441             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1442                     if !used.get() => {
1443                 used.set(true);
1444                 directive.used.set(true);
1445                 if legacy_self_import {
1446                     self.warn_legacy_self_import(directive);
1447                     return false;
1448                 }
1449                 self.used_imports.insert((directive.id, ns));
1450                 self.add_to_glob_map(directive.id, ident);
1451                 self.record_use(ident, ns, binding, span)
1452             }
1453             NameBindingKind::Import { .. } => false,
1454             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1455                 self.ambiguity_errors.push(AmbiguityError {
1456                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1457                 });
1458                 if legacy {
1459                     self.record_use(ident, ns, b1, span);
1460                 }
1461                 !legacy
1462             }
1463             _ => false
1464         }
1465     }
1466
1467     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1468         if self.make_glob_map {
1469             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1470         }
1471     }
1472
1473     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1474     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1475     /// `ident` in the first scope that defines it (or None if no scopes define it).
1476     ///
1477     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1478     /// the items are defined in the block. For example,
1479     /// ```rust
1480     /// fn f() {
1481     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1482     ///    let g = || {};
1483     ///    fn g() {}
1484     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1485     /// }
1486     /// ```
1487     ///
1488     /// Invariant: This must only be called during main resolution, not during
1489     /// import resolution.
1490     fn resolve_ident_in_lexical_scope(&mut self,
1491                                       mut ident: Ident,
1492                                       ns: Namespace,
1493                                       record_used: Option<Span>)
1494                                       -> Option<LexicalScopeBinding<'a>> {
1495         if ns == TypeNS {
1496             ident = ident.unhygienize();
1497         }
1498
1499         // Walk backwards up the ribs in scope.
1500         for i in (0 .. self.ribs[ns].len()).rev() {
1501             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1502                 // The ident resolves to a type parameter or local variable.
1503                 return Some(LexicalScopeBinding::Def(
1504                     self.adjust_local_def(ns, i, def, record_used)
1505                 ));
1506             }
1507
1508             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1509                 let item = self.resolve_ident_in_module(module, ident, ns, false, record_used);
1510                 if let Ok(binding) = item {
1511                     // The ident resolves to an item.
1512                     return Some(LexicalScopeBinding::Item(binding));
1513                 }
1514
1515                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1516                 } else if !module.no_implicit_prelude {
1517                     return self.prelude.and_then(|prelude| {
1518                         self.resolve_ident_in_module(prelude, ident, ns, false, None).ok()
1519                     }).map(LexicalScopeBinding::Item)
1520                 } else {
1521                     return None;
1522                 }
1523             }
1524
1525             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1526                 // If an invocation of this macro created `ident`, give up on `ident`
1527                 // and switch to `ident`'s source from the macro definition.
1528                 let ctxt_data = ident.ctxt.data();
1529                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1530                     ident.ctxt = ctxt_data.prev_ctxt;
1531                 }
1532             }
1533         }
1534
1535         None
1536     }
1537
1538     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext) -> Module<'a> {
1539         let mut ctxt_data = crate_var_ctxt.data();
1540         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1541             ctxt_data = ctxt_data.prev_ctxt.data();
1542         }
1543         let module = self.macro_def_scope(ctxt_data.outer_mark);
1544         if module.is_local() { self.graph_root } else { module }
1545     }
1546
1547     // AST resolution
1548     //
1549     // We maintain a list of value ribs and type ribs.
1550     //
1551     // Simultaneously, we keep track of the current position in the module
1552     // graph in the `current_module` pointer. When we go to resolve a name in
1553     // the value or type namespaces, we first look through all the ribs and
1554     // then query the module graph. When we resolve a name in the module
1555     // namespace, we can skip all the ribs (since nested modules are not
1556     // allowed within blocks in Rust) and jump straight to the current module
1557     // graph node.
1558     //
1559     // Named implementations are handled separately. When we find a method
1560     // call, we consult the module node to find all of the implementations in
1561     // scope. This information is lazily cached in the module node. We then
1562     // generate a fake "implementation scope" containing all the
1563     // implementations thus found, for compatibility with old resolve pass.
1564
1565     fn with_scope<F>(&mut self, id: NodeId, f: F)
1566         where F: FnOnce(&mut Resolver)
1567     {
1568         let id = self.definitions.local_def_id(id);
1569         let module = self.module_map.get(&id).cloned(); // clones a reference
1570         if let Some(module) = module {
1571             // Move down in the graph.
1572             let orig_module = replace(&mut self.current_module, module);
1573             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1574             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1575
1576             self.finalize_current_module_macro_resolutions();
1577             f(self);
1578
1579             self.current_module = orig_module;
1580             self.ribs[ValueNS].pop();
1581             self.ribs[TypeNS].pop();
1582         } else {
1583             f(self);
1584         }
1585     }
1586
1587     /// Searches the current set of local scopes for labels.
1588     /// Stops after meeting a closure.
1589     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1590         for rib in self.label_ribs.iter().rev() {
1591             match rib.kind {
1592                 NormalRibKind => {
1593                     // Continue
1594                 }
1595                 MacroDefinition(def) => {
1596                     // If an invocation of this macro created `ident`, give up on `ident`
1597                     // and switch to `ident`'s source from the macro definition.
1598                     let ctxt_data = ident.ctxt.data();
1599                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1600                         ident.ctxt = ctxt_data.prev_ctxt;
1601                     }
1602                 }
1603                 _ => {
1604                     // Do not resolve labels across function boundary
1605                     return None;
1606                 }
1607             }
1608             let result = rib.bindings.get(&ident).cloned();
1609             if result.is_some() {
1610                 return result;
1611             }
1612         }
1613         None
1614     }
1615
1616     fn resolve_item(&mut self, item: &Item) {
1617         let name = item.ident.name;
1618
1619         debug!("(resolving item) resolving {}", name);
1620
1621         self.check_proc_macro_attrs(&item.attrs);
1622
1623         match item.node {
1624             ItemKind::Enum(_, ref generics) |
1625             ItemKind::Ty(_, ref generics) |
1626             ItemKind::Struct(_, ref generics) |
1627             ItemKind::Union(_, ref generics) |
1628             ItemKind::Fn(.., ref generics, _) => {
1629                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1630                                              |this| visit::walk_item(this, item));
1631             }
1632
1633             ItemKind::DefaultImpl(_, ref trait_ref) => {
1634                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1635                     // Resolve type arguments in trait path
1636                     visit::walk_trait_ref(this, trait_ref);
1637                 });
1638             }
1639             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1640                 self.resolve_implementation(generics,
1641                                             opt_trait_ref,
1642                                             &self_type,
1643                                             item.id,
1644                                             impl_items),
1645
1646             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1647                 // Create a new rib for the trait-wide type parameters.
1648                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1649                     let local_def_id = this.definitions.local_def_id(item.id);
1650                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1651                         this.visit_generics(generics);
1652                         walk_list!(this, visit_ty_param_bound, bounds);
1653
1654                         for trait_item in trait_items {
1655                             this.check_proc_macro_attrs(&trait_item.attrs);
1656
1657                             match trait_item.node {
1658                                 TraitItemKind::Const(_, ref default) => {
1659                                     // Only impose the restrictions of
1660                                     // ConstRibKind if there's an actual constant
1661                                     // expression in a provided default.
1662                                     if default.is_some() {
1663                                         this.with_constant_rib(|this| {
1664                                             visit::walk_trait_item(this, trait_item)
1665                                         });
1666                                     } else {
1667                                         visit::walk_trait_item(this, trait_item)
1668                                     }
1669                                 }
1670                                 TraitItemKind::Method(ref sig, _) => {
1671                                     let type_parameters =
1672                                         HasTypeParameters(&sig.generics,
1673                                                           MethodRibKind(!sig.decl.has_self()));
1674                                     this.with_type_parameter_rib(type_parameters, |this| {
1675                                         visit::walk_trait_item(this, trait_item)
1676                                     });
1677                                 }
1678                                 TraitItemKind::Type(..) => {
1679                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1680                                         visit::walk_trait_item(this, trait_item)
1681                                     });
1682                                 }
1683                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1684                             };
1685                         }
1686                     });
1687                 });
1688             }
1689
1690             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1691                 self.with_scope(item.id, |this| {
1692                     visit::walk_item(this, item);
1693                 });
1694             }
1695
1696             ItemKind::Const(..) | ItemKind::Static(..) => {
1697                 self.with_constant_rib(|this| {
1698                     visit::walk_item(this, item);
1699                 });
1700             }
1701
1702             ItemKind::Use(ref view_path) => {
1703                 match view_path.node {
1704                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1705                         // Resolve prefix of an import with empty braces (issue #28388).
1706                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1707                     }
1708                     _ => {}
1709                 }
1710             }
1711
1712             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) => {
1713                 // do nothing, these are just around to be encoded
1714             }
1715
1716             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1717         }
1718     }
1719
1720     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1721         where F: FnOnce(&mut Resolver)
1722     {
1723         match type_parameters {
1724             HasTypeParameters(generics, rib_kind) => {
1725                 let mut function_type_rib = Rib::new(rib_kind);
1726                 let mut seen_bindings = FxHashMap();
1727                 for type_parameter in &generics.ty_params {
1728                     let name = type_parameter.ident.name;
1729                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1730
1731                     if seen_bindings.contains_key(&name) {
1732                         let span = seen_bindings.get(&name).unwrap();
1733                         resolve_error(self,
1734                                       type_parameter.span,
1735                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1736                                                                                           span));
1737                     }
1738                     seen_bindings.entry(name).or_insert(type_parameter.span);
1739
1740                     // plain insert (no renaming)
1741                     let def_id = self.definitions.local_def_id(type_parameter.id);
1742                     let def = Def::TyParam(def_id);
1743                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1744                     self.record_def(type_parameter.id, PathResolution::new(def));
1745                 }
1746                 self.ribs[TypeNS].push(function_type_rib);
1747             }
1748
1749             NoTypeParameters => {
1750                 // Nothing to do.
1751             }
1752         }
1753
1754         f(self);
1755
1756         if let HasTypeParameters(..) = type_parameters {
1757             self.ribs[TypeNS].pop();
1758         }
1759     }
1760
1761     fn with_label_rib<F>(&mut self, f: F)
1762         where F: FnOnce(&mut Resolver)
1763     {
1764         self.label_ribs.push(Rib::new(NormalRibKind));
1765         f(self);
1766         self.label_ribs.pop();
1767     }
1768
1769     fn with_constant_rib<F>(&mut self, f: F)
1770         where F: FnOnce(&mut Resolver)
1771     {
1772         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1773         self.ribs[TypeNS].push(Rib::new(ConstantItemRibKind));
1774         f(self);
1775         self.ribs[TypeNS].pop();
1776         self.ribs[ValueNS].pop();
1777     }
1778
1779     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1780         where F: FnOnce(&mut Resolver) -> T
1781     {
1782         // Handle nested impls (inside fn bodies)
1783         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1784         let result = f(self);
1785         self.current_self_type = previous_value;
1786         result
1787     }
1788
1789     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1790         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1791     {
1792         let mut new_val = None;
1793         let mut new_id = None;
1794         if let Some(trait_ref) = opt_trait_ref {
1795             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1796                                               &trait_ref.path, PathSource::Trait).base_def();
1797             if def != Def::Err {
1798                 new_val = Some((def.def_id(), trait_ref.clone()));
1799                 new_id = Some(def.def_id());
1800             }
1801         }
1802         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1803         let result = f(self, new_id);
1804         self.current_trait_ref = original_trait_ref;
1805         result
1806     }
1807
1808     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1809         where F: FnOnce(&mut Resolver)
1810     {
1811         let mut self_type_rib = Rib::new(NormalRibKind);
1812
1813         // plain insert (no renaming, types are not currently hygienic....)
1814         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1815         self.ribs[TypeNS].push(self_type_rib);
1816         f(self);
1817         self.ribs[TypeNS].pop();
1818     }
1819
1820     fn resolve_implementation(&mut self,
1821                               generics: &Generics,
1822                               opt_trait_reference: &Option<TraitRef>,
1823                               self_type: &Ty,
1824                               item_id: NodeId,
1825                               impl_items: &[ImplItem]) {
1826         // If applicable, create a rib for the type parameters.
1827         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1828             // Dummy self type for better errors if `Self` is used in the trait path.
1829             this.with_self_rib(Def::SelfTy(None, None), |this| {
1830                 // Resolve the trait reference, if necessary.
1831                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1832                     let item_def_id = this.definitions.local_def_id(item_id);
1833                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1834                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1835                             // Resolve type arguments in trait path
1836                             visit::walk_trait_ref(this, trait_ref);
1837                         }
1838                         // Resolve the self type.
1839                         this.visit_ty(self_type);
1840                         // Resolve the type parameters.
1841                         this.visit_generics(generics);
1842                         this.with_current_self_type(self_type, |this| {
1843                             for impl_item in impl_items {
1844                                 this.check_proc_macro_attrs(&impl_item.attrs);
1845                                 this.resolve_visibility(&impl_item.vis);
1846                                 match impl_item.node {
1847                                     ImplItemKind::Const(..) => {
1848                                         // If this is a trait impl, ensure the const
1849                                         // exists in trait
1850                                         this.check_trait_item(impl_item.ident.name,
1851                                                             ValueNS,
1852                                                             impl_item.span,
1853                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1854                                         visit::walk_impl_item(this, impl_item);
1855                                     }
1856                                     ImplItemKind::Method(ref sig, _) => {
1857                                         // If this is a trait impl, ensure the method
1858                                         // exists in trait
1859                                         this.check_trait_item(impl_item.ident.name,
1860                                                             ValueNS,
1861                                                             impl_item.span,
1862                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1863
1864                                         // We also need a new scope for the method-
1865                                         // specific type parameters.
1866                                         let type_parameters =
1867                                             HasTypeParameters(&sig.generics,
1868                                                             MethodRibKind(!sig.decl.has_self()));
1869                                         this.with_type_parameter_rib(type_parameters, |this| {
1870                                             visit::walk_impl_item(this, impl_item);
1871                                         });
1872                                     }
1873                                     ImplItemKind::Type(ref ty) => {
1874                                         // If this is a trait impl, ensure the type
1875                                         // exists in trait
1876                                         this.check_trait_item(impl_item.ident.name,
1877                                                             TypeNS,
1878                                                             impl_item.span,
1879                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1880
1881                                         this.visit_ty(ty);
1882                                     }
1883                                     ImplItemKind::Macro(_) =>
1884                                         panic!("unexpanded macro in resolve!"),
1885                                 }
1886                             }
1887                         });
1888                     });
1889                 });
1890             });
1891         });
1892     }
1893
1894     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1895         where F: FnOnce(Name, &str) -> ResolutionError
1896     {
1897         // If there is a TraitRef in scope for an impl, then the method must be in the
1898         // trait.
1899         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1900             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1901                 let path_str = path_names_to_string(&trait_ref.path);
1902                 resolve_error(self, span, err(name, &path_str));
1903             }
1904         }
1905     }
1906
1907     fn resolve_local(&mut self, local: &Local) {
1908         // Resolve the type.
1909         walk_list!(self, visit_ty, &local.ty);
1910
1911         // Resolve the initializer.
1912         walk_list!(self, visit_expr, &local.init);
1913
1914         // Resolve the pattern.
1915         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1916     }
1917
1918     // build a map from pattern identifiers to binding-info's.
1919     // this is done hygienically. This could arise for a macro
1920     // that expands into an or-pattern where one 'x' was from the
1921     // user and one 'x' came from the macro.
1922     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1923         let mut binding_map = FxHashMap();
1924
1925         pat.walk(&mut |pat| {
1926             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1927                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1928                     Some(Def::Local(..)) => true,
1929                     _ => false,
1930                 } {
1931                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1932                     binding_map.insert(ident.node, binding_info);
1933                 }
1934             }
1935             true
1936         });
1937
1938         binding_map
1939     }
1940
1941     // check that all of the arms in an or-pattern have exactly the
1942     // same set of bindings, with the same binding modes for each.
1943     fn check_consistent_bindings(&mut self, arm: &Arm) {
1944         if arm.pats.is_empty() {
1945             return;
1946         }
1947
1948         let mut missing_vars = FxHashMap();
1949         let mut inconsistent_vars = FxHashMap();
1950         for (i, p) in arm.pats.iter().enumerate() {
1951             let map_i = self.binding_mode_map(&p);
1952
1953             for (j, q) in arm.pats.iter().enumerate() {
1954                 if i == j {
1955                     continue;
1956                 }
1957
1958                 let map_j = self.binding_mode_map(&q);
1959                 for (&key, &binding_i) in &map_i {
1960                     if map_j.len() == 0 {                   // Account for missing bindings when
1961                         let binding_error = missing_vars    // map_j has none.
1962                             .entry(key.name)
1963                             .or_insert(BindingError {
1964                                 name: key.name,
1965                                 origin: BTreeSet::new(),
1966                                 target: BTreeSet::new(),
1967                             });
1968                         binding_error.origin.insert(binding_i.span);
1969                         binding_error.target.insert(q.span);
1970                     }
1971                     for (&key_j, &binding_j) in &map_j {
1972                         match map_i.get(&key_j) {
1973                             None => {  // missing binding
1974                                 let binding_error = missing_vars
1975                                     .entry(key_j.name)
1976                                     .or_insert(BindingError {
1977                                         name: key_j.name,
1978                                         origin: BTreeSet::new(),
1979                                         target: BTreeSet::new(),
1980                                     });
1981                                 binding_error.origin.insert(binding_j.span);
1982                                 binding_error.target.insert(p.span);
1983                             }
1984                             Some(binding_i) => {  // check consistent binding
1985                                 if binding_i.binding_mode != binding_j.binding_mode {
1986                                     inconsistent_vars
1987                                         .entry(key.name)
1988                                         .or_insert((binding_j.span, binding_i.span));
1989                                 }
1990                             }
1991                         }
1992                     }
1993                 }
1994             }
1995         }
1996         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
1997         missing_vars.sort();
1998         for (_, v) in missing_vars {
1999             resolve_error(self,
2000                           *v.origin.iter().next().unwrap(),
2001                           ResolutionError::VariableNotBoundInPattern(v));
2002         }
2003         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2004         inconsistent_vars.sort();
2005         for (name, v) in inconsistent_vars {
2006             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2007         }
2008     }
2009
2010     fn resolve_arm(&mut self, arm: &Arm) {
2011         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2012
2013         let mut bindings_list = FxHashMap();
2014         for pattern in &arm.pats {
2015             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2016         }
2017
2018         // This has to happen *after* we determine which
2019         // pat_idents are variants
2020         self.check_consistent_bindings(arm);
2021
2022         walk_list!(self, visit_expr, &arm.guard);
2023         self.visit_expr(&arm.body);
2024
2025         self.ribs[ValueNS].pop();
2026     }
2027
2028     fn resolve_block(&mut self, block: &Block) {
2029         debug!("(resolving block) entering block");
2030         // Move down in the graph, if there's an anonymous module rooted here.
2031         let orig_module = self.current_module;
2032         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2033
2034         let mut num_macro_definition_ribs = 0;
2035         if let Some(anonymous_module) = anonymous_module {
2036             debug!("(resolving block) found anonymous module, moving down");
2037             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2038             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2039             self.current_module = anonymous_module;
2040             self.finalize_current_module_macro_resolutions();
2041         } else {
2042             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2043         }
2044
2045         // Descend into the block.
2046         for stmt in &block.stmts {
2047             if let ast::StmtKind::Item(ref item) = stmt.node {
2048                 if let ast::ItemKind::MacroDef(..) = item.node {
2049                     num_macro_definition_ribs += 1;
2050                     let def = self.definitions.local_def_id(item.id);
2051                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2052                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2053                 }
2054             }
2055
2056             self.visit_stmt(stmt);
2057         }
2058
2059         // Move back up.
2060         self.current_module = orig_module;
2061         for _ in 0 .. num_macro_definition_ribs {
2062             self.ribs[ValueNS].pop();
2063             self.label_ribs.pop();
2064         }
2065         self.ribs[ValueNS].pop();
2066         if let Some(_) = anonymous_module {
2067             self.ribs[TypeNS].pop();
2068         }
2069         debug!("(resolving block) leaving block");
2070     }
2071
2072     fn fresh_binding(&mut self,
2073                      ident: &SpannedIdent,
2074                      pat_id: NodeId,
2075                      outer_pat_id: NodeId,
2076                      pat_src: PatternSource,
2077                      bindings: &mut FxHashMap<Ident, NodeId>)
2078                      -> PathResolution {
2079         // Add the binding to the local ribs, if it
2080         // doesn't already exist in the bindings map. (We
2081         // must not add it if it's in the bindings map
2082         // because that breaks the assumptions later
2083         // passes make about or-patterns.)
2084         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2085         match bindings.get(&ident.node).cloned() {
2086             Some(id) if id == outer_pat_id => {
2087                 // `Variant(a, a)`, error
2088                 resolve_error(
2089                     self,
2090                     ident.span,
2091                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2092                         &ident.node.name.as_str())
2093                 );
2094             }
2095             Some(..) if pat_src == PatternSource::FnParam => {
2096                 // `fn f(a: u8, a: u8)`, error
2097                 resolve_error(
2098                     self,
2099                     ident.span,
2100                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2101                         &ident.node.name.as_str())
2102                 );
2103             }
2104             Some(..) if pat_src == PatternSource::Match => {
2105                 // `Variant1(a) | Variant2(a)`, ok
2106                 // Reuse definition from the first `a`.
2107                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2108             }
2109             Some(..) => {
2110                 span_bug!(ident.span, "two bindings with the same name from \
2111                                        unexpected pattern source {:?}", pat_src);
2112             }
2113             None => {
2114                 // A completely fresh binding, add to the lists if it's valid.
2115                 if ident.node.name != keywords::Invalid.name() {
2116                     bindings.insert(ident.node, outer_pat_id);
2117                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2118                 }
2119             }
2120         }
2121
2122         PathResolution::new(def)
2123     }
2124
2125     fn resolve_pattern(&mut self,
2126                        pat: &Pat,
2127                        pat_src: PatternSource,
2128                        // Maps idents to the node ID for the
2129                        // outermost pattern that binds them.
2130                        bindings: &mut FxHashMap<Ident, NodeId>) {
2131         // Visit all direct subpatterns of this pattern.
2132         let outer_pat_id = pat.id;
2133         pat.walk(&mut |pat| {
2134             match pat.node {
2135                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2136                     // First try to resolve the identifier as some existing
2137                     // entity, then fall back to a fresh binding.
2138                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS, None)
2139                                       .and_then(LexicalScopeBinding::item);
2140                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2141                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2142                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2143                         match def {
2144                             Def::StructCtor(_, CtorKind::Const) |
2145                             Def::VariantCtor(_, CtorKind::Const) |
2146                             Def::Const(..) if !always_binding => {
2147                                 // A unit struct/variant or constant pattern.
2148                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2149                                 Some(PathResolution::new(def))
2150                             }
2151                             Def::StructCtor(..) | Def::VariantCtor(..) |
2152                             Def::Const(..) | Def::Static(..) => {
2153                                 // A fresh binding that shadows something unacceptable.
2154                                 resolve_error(
2155                                     self,
2156                                     ident.span,
2157                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2158                                         pat_src.descr(), ident.node.name, binding.unwrap())
2159                                 );
2160                                 None
2161                             }
2162                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2163                                 // These entities are explicitly allowed
2164                                 // to be shadowed by fresh bindings.
2165                                 None
2166                             }
2167                             def => {
2168                                 span_bug!(ident.span, "unexpected definition for an \
2169                                                        identifier in pattern: {:?}", def);
2170                             }
2171                         }
2172                     }).unwrap_or_else(|| {
2173                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2174                     });
2175
2176                     self.record_def(pat.id, resolution);
2177                 }
2178
2179                 PatKind::TupleStruct(ref path, ..) => {
2180                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2181                 }
2182
2183                 PatKind::Path(ref qself, ref path) => {
2184                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2185                 }
2186
2187                 PatKind::Struct(ref path, ..) => {
2188                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2189                 }
2190
2191                 _ => {}
2192             }
2193             true
2194         });
2195
2196         visit::walk_pat(self, pat);
2197     }
2198
2199     // High-level and context dependent path resolution routine.
2200     // Resolves the path and records the resolution into definition map.
2201     // If resolution fails tries several techniques to find likely
2202     // resolution candidates, suggest imports or other help, and report
2203     // errors in user friendly way.
2204     fn smart_resolve_path(&mut self,
2205                           id: NodeId,
2206                           qself: Option<&QSelf>,
2207                           path: &Path,
2208                           source: PathSource)
2209                           -> PathResolution {
2210         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2211         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2212         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2213     }
2214
2215     fn smart_resolve_path_fragment(&mut self,
2216                                    id: NodeId,
2217                                    qself: Option<&QSelf>,
2218                                    path: &[Ident],
2219                                    span: Span,
2220                                    ident_span: Span,
2221                                    source: PathSource)
2222                                    -> PathResolution {
2223         let ns = source.namespace();
2224         let is_expected = &|def| source.is_expected(def);
2225
2226         // Base error is amended with one short label and possibly some longer helps/notes.
2227         let report_errors = |this: &mut Self, def: Option<Def>| {
2228             // Make the base error.
2229             let expected = source.descr_expected();
2230             let path_str = names_to_string(path);
2231             let code = source.error_code(def.is_some());
2232             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2233                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2234                  format!("not a {}", expected), span)
2235             } else {
2236                 let item_str = path[path.len() - 1];
2237                 let (mod_prefix, mod_str) = if path.len() == 1 {
2238                     (format!(""), format!("this scope"))
2239                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2240                     (format!(""), format!("the crate root"))
2241                 } else {
2242                     let mod_path = &path[..path.len() - 1];
2243                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), None) {
2244                         PathResult::Module(module) => module.def(),
2245                         _ => None,
2246                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2247                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2248                 };
2249                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2250                  format!("not found in {}", mod_str), ident_span)
2251             };
2252             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2253
2254             // Emit special messages for unresolved `Self` and `self`.
2255             if is_self_type(path, ns) {
2256                 __diagnostic_used!(E0411);
2257                 err.code("E0411".into());
2258                 err.span_label(span, &format!("`Self` is only available in traits and impls"));
2259                 return err;
2260             }
2261             if is_self_value(path, ns) {
2262                 __diagnostic_used!(E0424);
2263                 err.code("E0424".into());
2264                 err.span_label(span, &format!("`self` value is only available in \
2265                                                methods with `self` parameter"));
2266                 return err;
2267             }
2268
2269             // Try to lookup the name in more relaxed fashion for better error reporting.
2270             let name = path.last().unwrap().name;
2271             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2272             if !candidates.is_empty() {
2273                 // Report import candidates as help and proceed searching for labels.
2274                 show_candidates(&mut err, &candidates, def.is_some());
2275             }
2276             if path.len() == 1 && this.self_type_is_available() {
2277                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2278                     let self_is_available = this.self_value_is_available(path[0].ctxt);
2279                     match candidate {
2280                         AssocSuggestion::Field => {
2281                             err.span_label(span, &format!("did you mean `self.{}`?", path_str));
2282                             if !self_is_available {
2283                                 err.span_label(span, &format!("`self` value is only available in \
2284                                                                methods with `self` parameter"));
2285                             }
2286                         }
2287                         AssocSuggestion::MethodWithSelf if self_is_available => {
2288                             err.span_label(span, &format!("did you mean `self.{}(...)`?",
2289                                                            path_str));
2290                         }
2291                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2292                             err.span_label(span, &format!("did you mean `Self::{}`?", path_str));
2293                         }
2294                     }
2295                     return err;
2296                 }
2297             }
2298
2299             // Try context dependent help if relaxed lookup didn't work.
2300             if let Some(def) = def {
2301                 match (def, source) {
2302                     (Def::Macro(..), _) => {
2303                         err.span_label(span, &format!("did you mean `{}!(...)`?", path_str));
2304                         return err;
2305                     }
2306                     (Def::TyAlias(..), PathSource::Trait) => {
2307                         err.span_label(span, &format!("type aliases cannot be used for traits"));
2308                         return err;
2309                     }
2310                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2311                         ExprKind::Field(_, ident) => {
2312                             err.span_label(parent.span, &format!("did you mean `{}::{}`?",
2313                                                                  path_str, ident.node));
2314                             return err;
2315                         }
2316                         ExprKind::MethodCall(ident, ..) => {
2317                             err.span_label(parent.span, &format!("did you mean `{}::{}(...)`?",
2318                                                                  path_str, ident.node));
2319                             return err;
2320                         }
2321                         _ => {}
2322                     },
2323                     _ if ns == ValueNS && is_struct_like(def) => {
2324                         if let Def::Struct(def_id) = def {
2325                             if let Some((ctor_def, ctor_vis))
2326                                     = this.struct_constructors.get(&def_id).cloned() {
2327                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2328                                     err.span_label(span, &format!("constructor is not visible \
2329                                                                    here due to private fields"));
2330                                 }
2331                             }
2332                         }
2333                         err.span_label(span, &format!("did you mean `{} {{ /* fields */ }}`?",
2334                                                        path_str));
2335                         return err;
2336                     }
2337                     _ => {}
2338                 }
2339             }
2340
2341             // Try Levenshtein if nothing else worked.
2342             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected) {
2343                 err.span_label(ident_span, &format!("did you mean `{}`?", candidate));
2344                 return err;
2345             }
2346
2347             // Fallback label.
2348             err.span_label(base_span, &fallback_label);
2349             err
2350         };
2351         let report_errors = |this: &mut Self, def: Option<Def>| {
2352             report_errors(this, def).emit();
2353             err_path_resolution()
2354         };
2355
2356         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2357                                                            source.defer_to_typeck(),
2358                                                            source.global_by_default()) {
2359             Some(resolution) if resolution.unresolved_segments() == 0 => {
2360                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2361                     resolution
2362                 } else {
2363                     // Add a temporary hack to smooth the transition to new struct ctor
2364                     // visibility rules. See #38932 for more details.
2365                     let mut res = None;
2366                     if let Def::Struct(def_id) = resolution.base_def() {
2367                         if let Some((ctor_def, ctor_vis))
2368                                 = self.struct_constructors.get(&def_id).cloned() {
2369                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2370                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2371                                 self.session.add_lint(lint, id, span,
2372                                     "private struct constructors are not usable through \
2373                                      reexports in outer modules".to_string());
2374                                 res = Some(PathResolution::new(ctor_def));
2375                             }
2376                         }
2377                     }
2378
2379                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2380                 }
2381             }
2382             Some(resolution) if source.defer_to_typeck() => {
2383                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2384                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2385                 // it needs to be added to the trait map.
2386                 if ns == ValueNS {
2387                     let item_name = path.last().unwrap().name;
2388                     let traits = self.get_traits_containing_item(item_name, ns);
2389                     self.trait_map.insert(id, traits);
2390                 }
2391                 resolution
2392             }
2393             _ => report_errors(self, None)
2394         };
2395
2396         if let PathSource::TraitItem(..) = source {} else {
2397             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2398             self.record_def(id, resolution);
2399         }
2400         resolution
2401     }
2402
2403     fn self_type_is_available(&mut self) -> bool {
2404         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(), TypeNS, None);
2405         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2406     }
2407
2408     fn self_value_is_available(&mut self, ctxt: SyntaxContext) -> bool {
2409         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2410         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None);
2411         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2412     }
2413
2414     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2415     fn resolve_qpath_anywhere(&mut self,
2416                               id: NodeId,
2417                               qself: Option<&QSelf>,
2418                               path: &[Ident],
2419                               primary_ns: Namespace,
2420                               span: Span,
2421                               defer_to_typeck: bool,
2422                               global_by_default: bool)
2423                               -> Option<PathResolution> {
2424         let mut fin_res = None;
2425         // FIXME: can't resolve paths in macro namespace yet, macros are
2426         // processed by the little special hack below.
2427         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2428             if i == 0 || ns != primary_ns {
2429                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2430                     // If defer_to_typeck, then resolution > no resolution,
2431                     // otherwise full resolution > partial resolution > no resolution.
2432                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2433                         return Some(res),
2434                     res => if fin_res.is_none() { fin_res = res },
2435                 };
2436             }
2437         }
2438         let is_global = self.global_macros.get(&path[0].name).cloned()
2439             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2440         if primary_ns != MacroNS && (is_global || self.macro_names.contains(&path[0].name)) {
2441             // Return some dummy definition, it's enough for error reporting.
2442             return Some(
2443                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2444             );
2445         }
2446         fin_res
2447     }
2448
2449     /// Handles paths that may refer to associated items.
2450     fn resolve_qpath(&mut self,
2451                      id: NodeId,
2452                      qself: Option<&QSelf>,
2453                      path: &[Ident],
2454                      ns: Namespace,
2455                      span: Span,
2456                      global_by_default: bool)
2457                      -> Option<PathResolution> {
2458         if let Some(qself) = qself {
2459             if qself.position == 0 {
2460                 // FIXME: Create some fake resolution that can't possibly be a type.
2461                 return Some(PathResolution::with_unresolved_segments(
2462                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2463                 ));
2464             }
2465             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2466             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2467             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2468                                                        span, span, PathSource::TraitItem(ns));
2469             return Some(PathResolution::with_unresolved_segments(
2470                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2471             ));
2472         }
2473
2474         let result = match self.resolve_path(&path, Some(ns), Some(span)) {
2475             PathResult::NonModule(path_res) => path_res,
2476             PathResult::Module(module) if !module.is_normal() => {
2477                 PathResolution::new(module.def().unwrap())
2478             }
2479             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2480             // don't report an error right away, but try to fallback to a primitive type.
2481             // So, we are still able to successfully resolve something like
2482             //
2483             // use std::u8; // bring module u8 in scope
2484             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2485             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2486             //                     // not to non-existent std::u8::max_value
2487             // }
2488             //
2489             // Such behavior is required for backward compatibility.
2490             // The same fallback is used when `a` resolves to nothing.
2491             PathResult::Module(..) | PathResult::Failed(..)
2492                     if (ns == TypeNS || path.len() > 1) &&
2493                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2494                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2495                 match prim {
2496                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2497                         if !self.session.features.borrow().i128_type {
2498                             emit_feature_err(&self.session.parse_sess,
2499                                                 "i128_type", span, GateIssue::Language,
2500                                                 "128-bit type is unstable");
2501
2502                         }
2503                     }
2504                     _ => {}
2505                 }
2506                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2507             }
2508             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2509             PathResult::Failed(msg, false) => {
2510                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2511                 err_path_resolution()
2512             }
2513             PathResult::Failed(..) => return None,
2514             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2515         };
2516
2517         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2518            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2519             let unqualified_result = {
2520                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
2521                     PathResult::NonModule(path_res) => path_res.base_def(),
2522                     PathResult::Module(module) => module.def().unwrap(),
2523                     _ => return Some(result),
2524                 }
2525             };
2526             if result.base_def() == unqualified_result {
2527                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2528                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2529             }
2530         }
2531
2532         Some(result)
2533     }
2534
2535     fn resolve_path(&mut self,
2536                     path: &[Ident],
2537                     opt_ns: Option<Namespace>, // `None` indicates a module path
2538                     record_used: Option<Span>)
2539                     -> PathResult<'a> {
2540         let mut module = None;
2541         let mut allow_super = true;
2542
2543         for (i, &ident) in path.iter().enumerate() {
2544             let is_last = i == path.len() - 1;
2545             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2546
2547             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2548                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2549                 continue
2550             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2551                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2552                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2553                 if let Some(parent) = self_module.parent {
2554                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2555                     continue
2556                 } else {
2557                     let msg = "There are too many initial `super`s.".to_string();
2558                     return PathResult::Failed(msg, false);
2559                 }
2560             }
2561             allow_super = false;
2562
2563             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2564                 module = Some(self.graph_root);
2565                 continue
2566             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2567                 module = Some(self.resolve_crate_var(ident.ctxt));
2568                 continue
2569             }
2570
2571             let binding = if let Some(module) = module {
2572                 self.resolve_ident_in_module(module, ident, ns, false, record_used)
2573             } else if opt_ns == Some(MacroNS) {
2574                 self.resolve_lexical_macro_path_segment(ident, ns, record_used)
2575                     .map(MacroBinding::binding)
2576             } else {
2577                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used) {
2578                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2579                     Some(LexicalScopeBinding::Def(def))
2580                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2581                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2582                             def, path.len() - 1
2583                         ));
2584                     }
2585                     _ => Err(if record_used.is_some() { Determined } else { Undetermined }),
2586                 }
2587             };
2588
2589             match binding {
2590                 Ok(binding) => {
2591                     let def = binding.def();
2592                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2593                     if let Some(next_module) = binding.module() {
2594                         module = Some(next_module);
2595                     } else if def == Def::Err {
2596                         return PathResult::NonModule(err_path_resolution());
2597                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2598                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2599                             def, path.len() - i - 1
2600                         ));
2601                     } else {
2602                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2603                     }
2604                 }
2605                 Err(Undetermined) => return PathResult::Indeterminate,
2606                 Err(Determined) => {
2607                     if let Some(module) = module {
2608                         if opt_ns.is_some() && !module.is_normal() {
2609                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2610                                 module.def().unwrap(), path.len() - i
2611                             ));
2612                         }
2613                     }
2614                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2615                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2616                         let mut candidates =
2617                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2618                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2619                         if let Some(candidate) = candidates.get(0) {
2620                             format!("Did you mean `{}`?", candidate.path)
2621                         } else {
2622                             format!("Maybe a missing `extern crate {};`?", ident)
2623                         }
2624                     } else if i == 0 {
2625                         format!("Use of undeclared type or module `{}`", ident)
2626                     } else {
2627                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2628                     };
2629                     return PathResult::Failed(msg, is_last);
2630                 }
2631             }
2632         }
2633
2634         PathResult::Module(module.unwrap_or(self.graph_root))
2635     }
2636
2637     // Resolve a local definition, potentially adjusting for closures.
2638     fn adjust_local_def(&mut self,
2639                         ns: Namespace,
2640                         rib_index: usize,
2641                         mut def: Def,
2642                         record_used: Option<Span>) -> Def {
2643         let ribs = &self.ribs[ns][rib_index + 1..];
2644
2645         // An invalid forward use of a type parameter from a previous default.
2646         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2647             if let Some(span) = record_used {
2648                 resolve_error(self, span,
2649                         ResolutionError::ForwardDeclaredTyParam);
2650             }
2651             assert_eq!(def, Def::Err);
2652             return Def::Err;
2653         }
2654
2655         match def {
2656             Def::Upvar(..) => {
2657                 span_bug!(record_used.unwrap_or(DUMMY_SP), "unexpected {:?} in bindings", def)
2658             }
2659             Def::Local(def_id) => {
2660                 for rib in ribs {
2661                     match rib.kind {
2662                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2663                         ForwardTyParamBanRibKind => {
2664                             // Nothing to do. Continue.
2665                         }
2666                         ClosureRibKind(function_id) => {
2667                             let prev_def = def;
2668                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2669
2670                             let seen = self.freevars_seen
2671                                            .entry(function_id)
2672                                            .or_insert_with(|| NodeMap());
2673                             if let Some(&index) = seen.get(&node_id) {
2674                                 def = Def::Upvar(def_id, index, function_id);
2675                                 continue;
2676                             }
2677                             let vec = self.freevars
2678                                           .entry(function_id)
2679                                           .or_insert_with(|| vec![]);
2680                             let depth = vec.len();
2681                             def = Def::Upvar(def_id, depth, function_id);
2682
2683                             if let Some(span) = record_used {
2684                                 vec.push(Freevar {
2685                                     def: prev_def,
2686                                     span: span,
2687                                 });
2688                                 seen.insert(node_id, depth);
2689                             }
2690                         }
2691                         ItemRibKind | MethodRibKind(_) => {
2692                             // This was an attempt to access an upvar inside a
2693                             // named function item. This is not allowed, so we
2694                             // report an error.
2695                             if let Some(span) = record_used {
2696                                 resolve_error(self, span,
2697                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2698                             }
2699                             return Def::Err;
2700                         }
2701                         ConstantItemRibKind => {
2702                             // Still doesn't deal with upvars
2703                             if let Some(span) = record_used {
2704                                 resolve_error(self, span,
2705                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2706                             }
2707                             return Def::Err;
2708                         }
2709                     }
2710                 }
2711             }
2712             Def::TyParam(..) | Def::SelfTy(..) => {
2713                 for rib in ribs {
2714                     match rib.kind {
2715                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2716                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind => {
2717                             // Nothing to do. Continue.
2718                         }
2719                         ItemRibKind => {
2720                             // This was an attempt to use a type parameter outside
2721                             // its scope.
2722                             if let Some(span) = record_used {
2723                                 resolve_error(self, span,
2724                                               ResolutionError::TypeParametersFromOuterFunction);
2725                             }
2726                             return Def::Err;
2727                         }
2728                         ConstantItemRibKind => {
2729                             // see #9186
2730                             if let Some(span) = record_used {
2731                                 resolve_error(self, span,
2732                                               ResolutionError::OuterTypeParameterContext);
2733                             }
2734                             return Def::Err;
2735                         }
2736                     }
2737                 }
2738             }
2739             _ => {}
2740         }
2741         return def;
2742     }
2743
2744     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2745     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2746     // FIXME #34673: This needs testing.
2747     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2748         where F: FnOnce(&mut Resolver<'a>) -> T,
2749     {
2750         self.with_empty_ribs(|this| {
2751             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2752             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2753             f(this)
2754         })
2755     }
2756
2757     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2758         where F: FnOnce(&mut Resolver<'a>) -> T,
2759     {
2760         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2761         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2762
2763         let result = f(self);
2764         self.ribs = ribs;
2765         self.label_ribs = label_ribs;
2766         result
2767     }
2768
2769     fn lookup_assoc_candidate<FilterFn>(&mut self,
2770                                         name: Name,
2771                                         ns: Namespace,
2772                                         filter_fn: FilterFn)
2773                                         -> Option<AssocSuggestion>
2774         where FilterFn: Fn(Def) -> bool
2775     {
2776         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2777             match t.node {
2778                 TyKind::Path(None, _) => Some(t.id),
2779                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2780                 // This doesn't handle the remaining `Ty` variants as they are not
2781                 // that commonly the self_type, it might be interesting to provide
2782                 // support for those in future.
2783                 _ => None,
2784             }
2785         }
2786
2787         // Fields are generally expected in the same contexts as locals.
2788         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2789             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2790                 // Look for a field with the same name in the current self_type.
2791                 if let Some(resolution) = self.def_map.get(&node_id) {
2792                     match resolution.base_def() {
2793                         Def::Struct(did) | Def::Union(did)
2794                                 if resolution.unresolved_segments() == 0 => {
2795                             if let Some(field_names) = self.field_names.get(&did) {
2796                                 if field_names.iter().any(|&field_name| name == field_name) {
2797                                     return Some(AssocSuggestion::Field);
2798                                 }
2799                             }
2800                         }
2801                         _ => {}
2802                     }
2803                 }
2804             }
2805         }
2806
2807         // Look for associated items in the current trait.
2808         if let Some((trait_did, _)) = self.current_trait_ref {
2809             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2810                 if filter_fn(def) {
2811                     return Some(if has_self {
2812                         AssocSuggestion::MethodWithSelf
2813                     } else {
2814                         AssocSuggestion::AssocItem
2815                     });
2816                 }
2817             }
2818         }
2819
2820         None
2821     }
2822
2823     fn lookup_typo_candidate<FilterFn>(&mut self,
2824                                        path: &[Ident],
2825                                        ns: Namespace,
2826                                        filter_fn: FilterFn)
2827                                        -> Option<Symbol>
2828         where FilterFn: Fn(Def) -> bool
2829     {
2830         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2831             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2832                 if let Some(binding) = resolution.borrow().binding {
2833                     if filter_fn(binding.def()) {
2834                         names.push(ident.name);
2835                     }
2836                 }
2837             }
2838         };
2839
2840         let mut names = Vec::new();
2841         if path.len() == 1 {
2842             // Search in lexical scope.
2843             // Walk backwards up the ribs in scope and collect candidates.
2844             for rib in self.ribs[ns].iter().rev() {
2845                 // Locals and type parameters
2846                 for (ident, def) in &rib.bindings {
2847                     if filter_fn(*def) {
2848                         names.push(ident.name);
2849                     }
2850                 }
2851                 // Items in scope
2852                 if let ModuleRibKind(module) = rib.kind {
2853                     // Items from this module
2854                     add_module_candidates(module, &mut names);
2855
2856                     if let ModuleKind::Block(..) = module.kind {
2857                         // We can see through blocks
2858                     } else {
2859                         // Items from the prelude
2860                         if let Some(prelude) = self.prelude {
2861                             if !module.no_implicit_prelude {
2862                                 add_module_candidates(prelude, &mut names);
2863                             }
2864                         }
2865                         break;
2866                     }
2867                 }
2868             }
2869             // Add primitive types to the mix
2870             if filter_fn(Def::PrimTy(TyBool)) {
2871                 for (name, _) in &self.primitive_type_table.primitive_types {
2872                     names.push(*name);
2873                 }
2874             }
2875         } else {
2876             // Search in module.
2877             let mod_path = &path[..path.len() - 1];
2878             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS), None) {
2879                 add_module_candidates(module, &mut names);
2880             }
2881         }
2882
2883         let name = path[path.len() - 1].name;
2884         // Make sure error reporting is deterministic.
2885         names.sort_by_key(|name| name.as_str());
2886         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2887             Some(found) if found != name => Some(found),
2888             _ => None,
2889         }
2890     }
2891
2892     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2893         where F: FnOnce(&mut Resolver)
2894     {
2895         if let Some(label) = label {
2896             let def = Def::Label(id);
2897             self.with_label_rib(|this| {
2898                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2899                 f(this);
2900             });
2901         } else {
2902             f(self);
2903         }
2904     }
2905
2906     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2907         self.with_resolved_label(label, id, |this| this.visit_block(block));
2908     }
2909
2910     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2911         // First, record candidate traits for this expression if it could
2912         // result in the invocation of a method call.
2913
2914         self.record_candidate_traits_for_expr_if_necessary(expr);
2915
2916         // Next, resolve the node.
2917         match expr.node {
2918             ExprKind::Path(ref qself, ref path) => {
2919                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2920                 visit::walk_expr(self, expr);
2921             }
2922
2923             ExprKind::Struct(ref path, ..) => {
2924                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2925                 visit::walk_expr(self, expr);
2926             }
2927
2928             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2929                 match self.search_label(label.node) {
2930                     None => {
2931                         self.record_def(expr.id, err_path_resolution());
2932                         resolve_error(self,
2933                                       label.span,
2934                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2935                     }
2936                     Some(def @ Def::Label(_)) => {
2937                         // Since this def is a label, it is never read.
2938                         self.record_def(expr.id, PathResolution::new(def));
2939                     }
2940                     Some(_) => {
2941                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2942                     }
2943                 }
2944
2945                 // visit `break` argument if any
2946                 visit::walk_expr(self, expr);
2947             }
2948
2949             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2950                 self.visit_expr(subexpression);
2951
2952                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2953                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
2954                 self.visit_block(if_block);
2955                 self.ribs[ValueNS].pop();
2956
2957                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
2958             }
2959
2960             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2961
2962             ExprKind::While(ref subexpression, ref block, label) => {
2963                 self.with_resolved_label(label, expr.id, |this| {
2964                     this.visit_expr(subexpression);
2965                     this.visit_block(block);
2966                 });
2967             }
2968
2969             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
2970                 self.with_resolved_label(label, expr.id, |this| {
2971                     this.visit_expr(subexpression);
2972                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
2973                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
2974                     this.visit_block(block);
2975                     this.ribs[ValueNS].pop();
2976                 });
2977             }
2978
2979             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
2980                 self.visit_expr(subexpression);
2981                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2982                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
2983
2984                 self.resolve_labeled_block(label, expr.id, block);
2985
2986                 self.ribs[ValueNS].pop();
2987             }
2988
2989             // Equivalent to `visit::walk_expr` + passing some context to children.
2990             ExprKind::Field(ref subexpression, _) => {
2991                 self.resolve_expr(subexpression, Some(expr));
2992             }
2993             ExprKind::MethodCall(_, ref types, ref arguments) => {
2994                 let mut arguments = arguments.iter();
2995                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2996                 for argument in arguments {
2997                     self.resolve_expr(argument, None);
2998                 }
2999                 for ty in types.iter() {
3000                     self.visit_ty(ty);
3001                 }
3002             }
3003
3004             ExprKind::Repeat(ref element, ref count) => {
3005                 self.visit_expr(element);
3006                 self.with_constant_rib(|this| {
3007                     this.visit_expr(count);
3008                 });
3009             }
3010             ExprKind::Call(ref callee, ref arguments) => {
3011                 self.resolve_expr(callee, Some(expr));
3012                 for argument in arguments {
3013                     self.resolve_expr(argument, None);
3014                 }
3015             }
3016
3017             _ => {
3018                 visit::walk_expr(self, expr);
3019             }
3020         }
3021     }
3022
3023     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3024         match expr.node {
3025             ExprKind::Field(_, name) => {
3026                 // FIXME(#6890): Even though you can't treat a method like a
3027                 // field, we need to add any trait methods we find that match
3028                 // the field name so that we can do some nice error reporting
3029                 // later on in typeck.
3030                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3031                 self.trait_map.insert(expr.id, traits);
3032             }
3033             ExprKind::MethodCall(name, ..) => {
3034                 debug!("(recording candidate traits for expr) recording traits for {}",
3035                        expr.id);
3036                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3037                 self.trait_map.insert(expr.id, traits);
3038             }
3039             _ => {
3040                 // Nothing to do.
3041             }
3042         }
3043     }
3044
3045     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3046         debug!("(getting traits containing item) looking for '{}'", name);
3047
3048         let mut found_traits = Vec::new();
3049         // Look for the current trait.
3050         if let Some((trait_def_id, _)) = self.current_trait_ref {
3051             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3052                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3053             }
3054         }
3055
3056         let mut search_module = self.current_module;
3057         loop {
3058             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3059             match search_module.kind {
3060                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3061                 _ => break,
3062             }
3063         }
3064
3065         if let Some(prelude) = self.prelude {
3066             if !search_module.no_implicit_prelude {
3067                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3068             }
3069         }
3070
3071         found_traits
3072     }
3073
3074     fn get_traits_in_module_containing_item(&mut self,
3075                                             name: Name,
3076                                             ns: Namespace,
3077                                             module: Module,
3078                                             found_traits: &mut Vec<TraitCandidate>) {
3079         let mut traits = module.traits.borrow_mut();
3080         if traits.is_none() {
3081             let mut collected_traits = Vec::new();
3082             module.for_each_child(|name, ns, binding| {
3083                 if ns != TypeNS { return }
3084                 if let Def::Trait(_) = binding.def() {
3085                     collected_traits.push((name, binding));
3086                 }
3087             });
3088             *traits = Some(collected_traits.into_boxed_slice());
3089         }
3090
3091         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3092             let trait_def_id = binding.def().def_id();
3093             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3094                 let import_id = match binding.kind {
3095                     NameBindingKind::Import { directive, .. } => {
3096                         self.maybe_unused_trait_imports.insert(directive.id);
3097                         self.add_to_glob_map(directive.id, trait_name);
3098                         Some(directive.id)
3099                     }
3100                     _ => None,
3101                 };
3102                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3103             }
3104         }
3105     }
3106
3107     /// When name resolution fails, this method can be used to look up candidate
3108     /// entities with the expected name. It allows filtering them using the
3109     /// supplied predicate (which should be used to only accept the types of
3110     /// definitions expected e.g. traits). The lookup spans across all crates.
3111     ///
3112     /// NOTE: The method does not look into imports, but this is not a problem,
3113     /// since we report the definitions (thus, the de-aliased imports).
3114     fn lookup_import_candidates<FilterFn>(&mut self,
3115                                           lookup_name: Name,
3116                                           namespace: Namespace,
3117                                           filter_fn: FilterFn)
3118                                           -> Vec<ImportSuggestion>
3119         where FilterFn: Fn(Def) -> bool
3120     {
3121         let mut candidates = Vec::new();
3122         let mut worklist = Vec::new();
3123         let mut seen_modules = FxHashSet();
3124         worklist.push((self.graph_root, Vec::new(), false));
3125
3126         while let Some((in_module,
3127                         path_segments,
3128                         in_module_is_extern)) = worklist.pop() {
3129             self.populate_module_if_necessary(in_module);
3130
3131             in_module.for_each_child(|ident, ns, name_binding| {
3132
3133                 // avoid imports entirely
3134                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3135                 // avoid non-importable candidates as well
3136                 if !name_binding.is_importable() { return; }
3137
3138                 // collect results based on the filter function
3139                 if ident.name == lookup_name && ns == namespace {
3140                     if filter_fn(name_binding.def()) {
3141                         // create the path
3142                         let mut segms = path_segments.clone();
3143                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3144                         let path = Path {
3145                             span: name_binding.span,
3146                             segments: segms,
3147                         };
3148                         // the entity is accessible in the following cases:
3149                         // 1. if it's defined in the same crate, it's always
3150                         // accessible (since private entities can be made public)
3151                         // 2. if it's defined in another crate, it's accessible
3152                         // only if both the module is public and the entity is
3153                         // declared as public (due to pruning, we don't explore
3154                         // outside crate private modules => no need to check this)
3155                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3156                             candidates.push(ImportSuggestion { path: path });
3157                         }
3158                     }
3159                 }
3160
3161                 // collect submodules to explore
3162                 if let Some(module) = name_binding.module() {
3163                     // form the path
3164                     let mut path_segments = path_segments.clone();
3165                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3166
3167                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3168                         // add the module to the lookup
3169                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3170                         if seen_modules.insert(module.def_id().unwrap()) {
3171                             worklist.push((module, path_segments, is_extern));
3172                         }
3173                     }
3174                 }
3175             })
3176         }
3177
3178         candidates
3179     }
3180
3181     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3182         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3183         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3184             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3185         }
3186     }
3187
3188     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3189         match *vis {
3190             ast::Visibility::Public => ty::Visibility::Public,
3191             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3192             ast::Visibility::Inherited => {
3193                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3194             }
3195             ast::Visibility::Restricted { ref path, id } => {
3196                 let def = self.smart_resolve_path(id, None, path,
3197                                                   PathSource::Visibility).base_def();
3198                 if def == Def::Err {
3199                     ty::Visibility::Public
3200                 } else {
3201                     let vis = ty::Visibility::Restricted(def.def_id());
3202                     if self.is_accessible(vis) {
3203                         vis
3204                     } else {
3205                         self.session.span_err(path.span, "visibilities can only be restricted \
3206                                                           to ancestor modules");
3207                         ty::Visibility::Public
3208                     }
3209                 }
3210             }
3211         }
3212     }
3213
3214     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3215         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3216     }
3217
3218     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3219         vis.is_accessible_from(module.normal_ancestor_id, self)
3220     }
3221
3222     fn report_errors(&mut self) {
3223         self.report_shadowing_errors();
3224         let mut reported_spans = FxHashSet();
3225
3226         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3227             if !reported_spans.insert(span) { continue }
3228             let participle = |binding: &NameBinding| {
3229                 if binding.is_import() { "imported" } else { "defined" }
3230             };
3231             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3232             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3233             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3234                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3235             } else if let Def::Macro(..) = b1.def() {
3236                 format!("macro-expanded {} do not shadow",
3237                         if b1.is_import() { "macro imports" } else { "macros" })
3238             } else {
3239                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3240                         if b1.is_import() { "imports" } else { "items" })
3241             };
3242             if legacy {
3243                 let id = match b2.kind {
3244                     NameBindingKind::Import { directive, .. } => directive.id,
3245                     _ => unreachable!(),
3246                 };
3247                 let mut span = MultiSpan::from_span(span);
3248                 span.push_span_label(b1.span, msg1);
3249                 span.push_span_label(b2.span, msg2);
3250                 let msg = format!("`{}` is ambiguous", name);
3251                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3252             } else {
3253                 let mut err =
3254                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3255                 err.span_note(b1.span, &msg1);
3256                 match b2.def() {
3257                     Def::Macro(..) if b2.span == DUMMY_SP =>
3258                         err.note(&format!("`{}` is also a builtin macro", name)),
3259                     _ => err.span_note(b2.span, &msg2),
3260                 };
3261                 err.note(&note).emit();
3262             }
3263         }
3264
3265         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3266             if !reported_spans.insert(span) { continue }
3267             if binding.is_extern_crate() {
3268                 // Warn when using an inaccessible extern crate.
3269                 let node_id = match binding.kind {
3270                     NameBindingKind::Import { directive, .. } => directive.id,
3271                     _ => unreachable!(),
3272                 };
3273                 let msg = format!("extern crate `{}` is private", name);
3274                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3275             } else {
3276                 let def = binding.def();
3277                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3278             }
3279         }
3280     }
3281
3282     fn report_shadowing_errors(&mut self) {
3283         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3284             self.resolve_legacy_scope(scope, name, true);
3285         }
3286
3287         let mut reported_errors = FxHashSet();
3288         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3289             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3290                reported_errors.insert((binding.name, binding.span)) {
3291                 let msg = format!("`{}` is already in scope", binding.name);
3292                 self.session.struct_span_err(binding.span, &msg)
3293                     .note("macro-expanded `macro_rules!`s may not shadow \
3294                            existing macros (see RFC 1560)")
3295                     .emit();
3296             }
3297         }
3298     }
3299
3300     fn report_conflict(&mut self,
3301                        parent: Module,
3302                        ident: Ident,
3303                        ns: Namespace,
3304                        binding: &NameBinding,
3305                        old_binding: &NameBinding) {
3306         // Error on the second of two conflicting names
3307         if old_binding.span.lo > binding.span.lo {
3308             return self.report_conflict(parent, ident, ns, old_binding, binding);
3309         }
3310
3311         let container = match parent.kind {
3312             ModuleKind::Def(Def::Mod(_), _) => "module",
3313             ModuleKind::Def(Def::Trait(_), _) => "trait",
3314             ModuleKind::Block(..) => "block",
3315             _ => "enum",
3316         };
3317
3318         let (participle, noun) = match old_binding.is_import() {
3319             true => ("imported", "import"),
3320             false => ("defined", "definition"),
3321         };
3322
3323         let (name, span) = (ident.name, binding.span);
3324
3325         if let Some(s) = self.name_already_seen.get(&name) {
3326             if s == &span {
3327                 return;
3328             }
3329         }
3330
3331         let msg = {
3332             let kind = match (ns, old_binding.module()) {
3333                 (ValueNS, _) => "a value",
3334                 (MacroNS, _) => "a macro",
3335                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3336                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3337                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3338                 (TypeNS, _) => "a type",
3339             };
3340             format!("{} named `{}` has already been {} in this {}",
3341                     kind, name, participle, container)
3342         };
3343
3344         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3345             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3346             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3347                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3348                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3349             },
3350             _ => match (old_binding.is_import(), binding.is_import()) {
3351                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3352                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3353                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3354             },
3355         };
3356
3357         err.span_label(span, &format!("`{}` already {}", name, participle));
3358         if old_binding.span != syntax_pos::DUMMY_SP {
3359             err.span_label(old_binding.span, &format!("previous {} of `{}` here", noun, name));
3360         }
3361         err.emit();
3362         self.name_already_seen.insert(name, span);
3363     }
3364
3365     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3366         let (id, span) = (directive.id, directive.span);
3367         let msg = "`self` no longer imports values".to_string();
3368         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3369     }
3370
3371     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3372         if self.proc_macro_enabled { return; }
3373
3374         for attr in attrs {
3375             if attr.path.segments.len() > 1 {
3376                 continue
3377             }
3378             let ident = attr.path.segments[0].identifier;
3379             let result = self.resolve_lexical_macro_path_segment(ident, MacroNS, None);
3380             if let Ok(binding) = result {
3381                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3382                     attr::mark_known(attr);
3383
3384                     let msg = "attribute procedural macros are experimental";
3385                     let feature = "proc_macro";
3386
3387                     feature_err(&self.session.parse_sess, feature,
3388                                 attr.span, GateIssue::Language, msg)
3389                         .span_note(binding.span(), "procedural macro imported here")
3390                         .emit();
3391                 }
3392             }
3393         }
3394     }
3395 }
3396
3397 fn is_struct_like(def: Def) -> bool {
3398     match def {
3399         Def::VariantCtor(_, CtorKind::Fictive) => true,
3400         _ => PathSource::Struct.is_expected(def),
3401     }
3402 }
3403
3404 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3405     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3406 }
3407
3408 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3409     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3410 }
3411
3412 fn names_to_string(idents: &[Ident]) -> String {
3413     let mut result = String::new();
3414     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3415         if i > 0 {
3416             result.push_str("::");
3417         }
3418         result.push_str(&ident.name.as_str());
3419     }
3420     result
3421 }
3422
3423 fn path_names_to_string(path: &Path) -> String {
3424     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3425 }
3426
3427 /// When an entity with a given name is not available in scope, we search for
3428 /// entities with that name in all crates. This method allows outputting the
3429 /// results of this search in a programmer-friendly way
3430 fn show_candidates(session: &mut DiagnosticBuilder,
3431                    candidates: &[ImportSuggestion],
3432                    better: bool) {
3433     // don't show more than MAX_CANDIDATES results, so
3434     // we're consistent with the trait suggestions
3435     const MAX_CANDIDATES: usize = 4;
3436
3437     // we want consistent results across executions, but candidates are produced
3438     // by iterating through a hash map, so make sure they are ordered:
3439     let mut path_strings: Vec<_> =
3440         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3441     path_strings.sort();
3442
3443     let better = if better { "better " } else { "" };
3444     let msg_diff = match path_strings.len() {
3445         1 => " is found in another module, you can import it",
3446         _ => "s are found in other modules, you can import them",
3447     };
3448
3449     let end = cmp::min(MAX_CANDIDATES, path_strings.len());
3450     session.help(&format!("possible {}candidate{} into scope:{}{}",
3451                           better,
3452                           msg_diff,
3453                           &path_strings[0..end].iter().map(|candidate| {
3454                               format!("\n  `use {};`", candidate)
3455                           }).collect::<String>(),
3456                           if path_strings.len() > MAX_CANDIDATES {
3457                               format!("\nand {} other candidates",
3458                                       path_strings.len() - MAX_CANDIDATES)
3459                           } else {
3460                               "".to_owned()
3461                           }
3462                           ));
3463 }
3464
3465 /// A somewhat inefficient routine to obtain the name of a module.
3466 fn module_to_string(module: Module) -> String {
3467     let mut names = Vec::new();
3468
3469     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3470         if let ModuleKind::Def(_, name) = module.kind {
3471             if let Some(parent) = module.parent {
3472                 names.push(Ident::with_empty_ctxt(name));
3473                 collect_mod(names, parent);
3474             }
3475         } else {
3476             // danger, shouldn't be ident?
3477             names.push(Ident::from_str("<opaque>"));
3478             collect_mod(names, module.parent.unwrap());
3479         }
3480     }
3481     collect_mod(&mut names, module);
3482
3483     if names.is_empty() {
3484         return "???".to_string();
3485     }
3486     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3487 }
3488
3489 fn err_path_resolution() -> PathResolution {
3490     PathResolution::new(Def::Err)
3491 }
3492
3493 #[derive(PartialEq,Copy, Clone)]
3494 pub enum MakeGlobMap {
3495     Yes,
3496     No,
3497 }
3498
3499 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }