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, "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, "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, "bound in different ways");
 259             err.span_label(first_binding_span, "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, "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, "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, "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, true, 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     /// Span of the module itself. Used for error reporting.
 870     span: Span,
 871 }
 872
 873 pub type Module<'a> = &'a ModuleData<'a>;
 874
 875 impl<'a> ModuleData<'a> {
 876     fn new(parent: Option<Module<'a>>,
 877            kind: ModuleKind,
 878            normal_ancestor_id: DefId,
 879            span: Span) -> Self {
 880         ModuleData {
 881             parent: parent,
 882             kind: kind,
 883             normal_ancestor_id: normal_ancestor_id,
 884             resolutions: RefCell::new(FxHashMap()),
 885             legacy_macro_resolutions: RefCell::new(Vec::new()),
 886             macro_resolutions: RefCell::new(Vec::new()),
 887             unresolved_invocations: RefCell::new(FxHashSet()),
 888             no_implicit_prelude: false,
 889             glob_importers: RefCell::new(Vec::new()),
 890             globs: RefCell::new((Vec::new())),
 891             traits: RefCell::new(None),
 892             populated: Cell::new(normal_ancestor_id.is_local()),
 893             span: span,
 894         }
 895     }
 896
 897     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 898         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 899             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 900         }
 901     }
 902
 903     fn def(&self) -> Option<Def> {
 904         match self.kind {
 905             ModuleKind::Def(def, _) => Some(def),
 906             _ => None,
 907         }
 908     }
 909
 910     fn def_id(&self) -> Option<DefId> {
 911         self.def().as_ref().map(Def::def_id)
 912     }
 913
 914     // `self` resolves to the first module ancestor that `is_normal`.
 915     fn is_normal(&self) -> bool {
 916         match self.kind {
 917             ModuleKind::Def(Def::Mod(_), _) => true,
 918             _ => false,
 919         }
 920     }
 921
 922     fn is_trait(&self) -> bool {
 923         match self.kind {
 924             ModuleKind::Def(Def::Trait(_), _) => true,
 925             _ => false,
 926         }
 927     }
 928
 929     fn is_local(&self) -> bool {
 930         self.normal_ancestor_id.is_local()
 931     }
 932
 933     fn nearest_item_scope(&'a self) -> Module<'a> {
 934         if self.is_trait() { self.parent.unwrap() } else { self }
 935     }
 936 }
 937
 938 impl<'a> fmt::Debug for ModuleData<'a> {
 939     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 940         write!(f, "{:?}", self.def())
 941     }
 942 }
 943
 944 // Records a possibly-private value, type, or module definition.
 945 #[derive(Clone, Debug)]
 946 pub struct NameBinding<'a> {
 947     kind: NameBindingKind<'a>,
 948     expansion: Mark,
 949     span: Span,
 950     vis: ty::Visibility,
 951 }
 952
 953 pub trait ToNameBinding<'a> {
 954     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 955 }
 956
 957 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 958     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 959         self
 960     }
 961 }
 962
 963 #[derive(Clone, Debug)]
 964 enum NameBindingKind<'a> {
 965     Def(Def),
 966     Module(Module<'a>),
 967     Import {
 968         binding: &'a NameBinding<'a>,
 969         directive: &'a ImportDirective<'a>,
 970         used: Cell<bool>,
 971         legacy_self_import: bool,
 972     },
 973     Ambiguity {
 974         b1: &'a NameBinding<'a>,
 975         b2: &'a NameBinding<'a>,
 976         legacy: bool,
 977     }
 978 }
 979
 980 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 981
 982 struct AmbiguityError<'a> {
 983     span: Span,
 984     name: Name,
 985     lexical: bool,
 986     b1: &'a NameBinding<'a>,
 987     b2: &'a NameBinding<'a>,
 988     legacy: bool,
 989 }
 990
 991 impl<'a> NameBinding<'a> {
 992     fn module(&self) -> Option<Module<'a>> {
 993         match self.kind {
 994             NameBindingKind::Module(module) => Some(module),
 995             NameBindingKind::Import { binding, .. } => binding.module(),
 996             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 997             _ => None,
 998         }
 999     }
1000
1001     fn def(&self) -> Def {
1002         match self.kind {
1003             NameBindingKind::Def(def) => def,
1004             NameBindingKind::Module(module) => module.def().unwrap(),
1005             NameBindingKind::Import { binding, .. } => binding.def(),
1006             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1007             NameBindingKind::Ambiguity { .. } => Def::Err,
1008         }
1009     }
1010
1011     fn def_ignoring_ambiguity(&self) -> Def {
1012         match self.kind {
1013             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1014             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1015             _ => self.def(),
1016         }
1017     }
1018
1019     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1020         resolver.get_macro(self.def_ignoring_ambiguity())
1021     }
1022
1023     // We sometimes need to treat variants as `pub` for backwards compatibility
1024     fn pseudo_vis(&self) -> ty::Visibility {
1025         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1026     }
1027
1028     fn is_variant(&self) -> bool {
1029         match self.kind {
1030             NameBindingKind::Def(Def::Variant(..)) |
1031             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1032             _ => false,
1033         }
1034     }
1035
1036     fn is_extern_crate(&self) -> bool {
1037         match self.kind {
1038             NameBindingKind::Import {
1039                 directive: &ImportDirective {
1040                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1041                 }, ..
1042             } => true,
1043             _ => false,
1044         }
1045     }
1046
1047     fn is_import(&self) -> bool {
1048         match self.kind {
1049             NameBindingKind::Import { .. } => true,
1050             _ => false,
1051         }
1052     }
1053
1054     fn is_glob_import(&self) -> bool {
1055         match self.kind {
1056             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1057             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1058             _ => false,
1059         }
1060     }
1061
1062     fn is_importable(&self) -> bool {
1063         match self.def() {
1064             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1065             _ => true,
1066         }
1067     }
1068 }
1069
1070 /// Interns the names of the primitive types.
1071 struct PrimitiveTypeTable {
1072     primitive_types: FxHashMap<Name, PrimTy>,
1073 }
1074
1075 impl PrimitiveTypeTable {
1076     fn new() -> PrimitiveTypeTable {
1077         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1078
1079         table.intern("bool", TyBool);
1080         table.intern("char", TyChar);
1081         table.intern("f32", TyFloat(FloatTy::F32));
1082         table.intern("f64", TyFloat(FloatTy::F64));
1083         table.intern("isize", TyInt(IntTy::Is));
1084         table.intern("i8", TyInt(IntTy::I8));
1085         table.intern("i16", TyInt(IntTy::I16));
1086         table.intern("i32", TyInt(IntTy::I32));
1087         table.intern("i64", TyInt(IntTy::I64));
1088         table.intern("i128", TyInt(IntTy::I128));
1089         table.intern("str", TyStr);
1090         table.intern("usize", TyUint(UintTy::Us));
1091         table.intern("u8", TyUint(UintTy::U8));
1092         table.intern("u16", TyUint(UintTy::U16));
1093         table.intern("u32", TyUint(UintTy::U32));
1094         table.intern("u64", TyUint(UintTy::U64));
1095         table.intern("u128", TyUint(UintTy::U128));
1096         table
1097     }
1098
1099     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1100         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1101     }
1102 }
1103
1104 /// The main resolver class.
1105 pub struct Resolver<'a> {
1106     session: &'a Session,
1107
1108     pub definitions: Definitions,
1109
1110     graph_root: Module<'a>,
1111
1112     prelude: Option<Module<'a>>,
1113
1114     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1115
1116     // Names of fields of an item `DefId` accessible with dot syntax.
1117     // Used for hints during error reporting.
1118     field_names: FxHashMap<DefId, Vec<Name>>,
1119
1120     // All imports known to succeed or fail.
1121     determined_imports: Vec<&'a ImportDirective<'a>>,
1122
1123     // All non-determined imports.
1124     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1125
1126     // The module that represents the current item scope.
1127     current_module: Module<'a>,
1128
1129     // The current set of local scopes for types and values.
1130     // FIXME #4948: Reuse ribs to avoid allocation.
1131     ribs: PerNS<Vec<Rib<'a>>>,
1132
1133     // The current set of local scopes, for labels.
1134     label_ribs: Vec<Rib<'a>>,
1135
1136     // The trait that the current context can refer to.
1137     current_trait_ref: Option<(DefId, TraitRef)>,
1138
1139     // The current self type if inside an impl (used for better errors).
1140     current_self_type: Option<Ty>,
1141
1142     // The idents for the primitive types.
1143     primitive_type_table: PrimitiveTypeTable,
1144
1145     def_map: DefMap,
1146     pub freevars: FreevarMap,
1147     freevars_seen: NodeMap<NodeMap<usize>>,
1148     pub export_map: ExportMap,
1149     pub trait_map: TraitMap,
1150
1151     // A map from nodes to anonymous modules.
1152     // Anonymous modules are pseudo-modules that are implicitly created around items
1153     // contained within blocks.
1154     //
1155     // For example, if we have this:
1156     //
1157     //  fn f() {
1158     //      fn g() {
1159     //          ...
1160     //      }
1161     //  }
1162     //
1163     // There will be an anonymous module created around `g` with the ID of the
1164     // entry block for `f`.
1165     block_map: NodeMap<Module<'a>>,
1166     module_map: FxHashMap<DefId, Module<'a>>,
1167     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1168
1169     pub make_glob_map: bool,
1170     // Maps imports to the names of items actually imported (this actually maps
1171     // all imports, but only glob imports are actually interesting).
1172     pub glob_map: GlobMap,
1173
1174     used_imports: FxHashSet<(NodeId, Namespace)>,
1175     pub maybe_unused_trait_imports: NodeSet,
1176
1177     privacy_errors: Vec<PrivacyError<'a>>,
1178     ambiguity_errors: Vec<AmbiguityError<'a>>,
1179     gated_errors: FxHashSet<Span>,
1180     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1181
1182     arenas: &'a ResolverArenas<'a>,
1183     dummy_binding: &'a NameBinding<'a>,
1184     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1185
1186     crate_loader: &'a mut CrateLoader,
1187     macro_names: FxHashSet<Name>,
1188     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1189     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1190     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1191     macro_defs: FxHashMap<Mark, DefId>,
1192     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1193     macro_exports: Vec<Export>,
1194     pub whitelisted_legacy_custom_derives: Vec<Name>,
1195     pub found_unresolved_macro: bool,
1196
1197     // Maps the `Mark` of an expansion to its containing module or block.
1198     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1199
1200     // Avoid duplicated errors for "name already defined".
1201     name_already_seen: FxHashMap<Name, Span>,
1202
1203     // If `#![feature(proc_macro)]` is set
1204     proc_macro_enabled: bool,
1205
1206     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1207     warned_proc_macros: FxHashSet<Name>,
1208
1209     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1210
1211     // This table maps struct IDs into struct constructor IDs,
1212     // it's not used during normal resolution, only for better error reporting.
1213     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1214 }
1215
1216 pub struct ResolverArenas<'a> {
1217     modules: arena::TypedArena<ModuleData<'a>>,
1218     local_modules: RefCell<Vec<Module<'a>>>,
1219     name_bindings: arena::TypedArena<NameBinding<'a>>,
1220     import_directives: arena::TypedArena<ImportDirective<'a>>,
1221     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1222     invocation_data: arena::TypedArena<InvocationData<'a>>,
1223     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1224 }
1225
1226 impl<'a> ResolverArenas<'a> {
1227     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1228         let module = self.modules.alloc(module);
1229         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1230             self.local_modules.borrow_mut().push(module);
1231         }
1232         module
1233     }
1234     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1235         self.local_modules.borrow()
1236     }
1237     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1238         self.name_bindings.alloc(name_binding)
1239     }
1240     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1241                               -> &'a ImportDirective {
1242         self.import_directives.alloc(import_directive)
1243     }
1244     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1245         self.name_resolutions.alloc(Default::default())
1246     }
1247     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1248                              -> &'a InvocationData<'a> {
1249         self.invocation_data.alloc(expansion_data)
1250     }
1251     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1252         self.legacy_bindings.alloc(binding)
1253     }
1254 }
1255
1256 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1257     fn parent(self, id: DefId) -> Option<DefId> {
1258         match id.krate {
1259             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1260             _ => self.session.cstore.def_key(id).parent,
1261         }.map(|index| DefId { index: index, ..id })
1262     }
1263 }
1264
1265 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1266     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1267         let namespace = if is_value { ValueNS } else { TypeNS };
1268         let hir::Path { ref segments, span, ref mut def } = *path;
1269         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1270         match self.resolve_path(&path, Some(namespace), true, span) {
1271             PathResult::Module(module) => *def = module.def().unwrap(),
1272             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1273                 *def = path_res.base_def(),
1274             PathResult::NonModule(..) => match self.resolve_path(&path, None, true, span) {
1275                 PathResult::Failed(msg, _) => {
1276                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1277                 }
1278                 _ => {}
1279             },
1280             PathResult::Indeterminate => unreachable!(),
1281             PathResult::Failed(msg, _) => {
1282                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1283             }
1284         }
1285     }
1286
1287     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1288         self.def_map.get(&id).cloned()
1289     }
1290
1291     fn definitions(&mut self) -> &mut Definitions {
1292         &mut self.definitions
1293     }
1294 }
1295
1296 impl<'a> Resolver<'a> {
1297     pub fn new(session: &'a Session,
1298                krate: &Crate,
1299                crate_name: &str,
1300                make_glob_map: MakeGlobMap,
1301                crate_loader: &'a mut CrateLoader,
1302                arenas: &'a ResolverArenas<'a>)
1303                -> Resolver<'a> {
1304         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1305         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1306         let graph_root = arenas.alloc_module(ModuleData {
1307             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1308             ..ModuleData::new(None, root_module_kind, root_def_id, krate.span)
1309         });
1310         let mut module_map = FxHashMap();
1311         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1312
1313         let mut definitions = Definitions::new();
1314         DefCollector::new(&mut definitions)
1315             .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
1316
1317         let mut invocations = FxHashMap();
1318         invocations.insert(Mark::root(),
1319                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1320
1321         let features = session.features.borrow();
1322
1323         let mut macro_defs = FxHashMap();
1324         macro_defs.insert(Mark::root(), root_def_id);
1325
1326         Resolver {
1327             session: session,
1328
1329             definitions: definitions,
1330
1331             // The outermost module has def ID 0; this is not reflected in the
1332             // AST.
1333             graph_root: graph_root,
1334             prelude: None,
1335
1336             trait_item_map: FxHashMap(),
1337             field_names: FxHashMap(),
1338
1339             determined_imports: Vec::new(),
1340             indeterminate_imports: Vec::new(),
1341
1342             current_module: graph_root,
1343             ribs: PerNS {
1344                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1345                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1346                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1347             },
1348             label_ribs: Vec::new(),
1349
1350             current_trait_ref: None,
1351             current_self_type: None,
1352
1353             primitive_type_table: PrimitiveTypeTable::new(),
1354
1355             def_map: NodeMap(),
1356             freevars: NodeMap(),
1357             freevars_seen: NodeMap(),
1358             export_map: NodeMap(),
1359             trait_map: NodeMap(),
1360             module_map: module_map,
1361             block_map: NodeMap(),
1362             extern_crate_roots: FxHashMap(),
1363
1364             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1365             glob_map: NodeMap(),
1366
1367             used_imports: FxHashSet(),
1368             maybe_unused_trait_imports: NodeSet(),
1369
1370             privacy_errors: Vec::new(),
1371             ambiguity_errors: Vec::new(),
1372             gated_errors: FxHashSet(),
1373             disallowed_shadowing: Vec::new(),
1374
1375             arenas: arenas,
1376             dummy_binding: arenas.alloc_name_binding(NameBinding {
1377                 kind: NameBindingKind::Def(Def::Err),
1378                 expansion: Mark::root(),
1379                 span: DUMMY_SP,
1380                 vis: ty::Visibility::Public,
1381             }),
1382
1383             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1384             use_extern_macros: features.use_extern_macros || features.proc_macro,
1385
1386             crate_loader: crate_loader,
1387             macro_names: FxHashSet(),
1388             global_macros: FxHashMap(),
1389             lexical_macro_resolutions: Vec::new(),
1390             macro_map: FxHashMap(),
1391             macro_exports: Vec::new(),
1392             invocations: invocations,
1393             macro_defs: macro_defs,
1394             local_macro_def_scopes: FxHashMap(),
1395             name_already_seen: FxHashMap(),
1396             whitelisted_legacy_custom_derives: Vec::new(),
1397             proc_macro_enabled: features.proc_macro,
1398             warned_proc_macros: FxHashSet(),
1399             potentially_unused_imports: Vec::new(),
1400             struct_constructors: DefIdMap(),
1401             found_unresolved_macro: false,
1402         }
1403     }
1404
1405     pub fn arenas() -> ResolverArenas<'a> {
1406         ResolverArenas {
1407             modules: arena::TypedArena::new(),
1408             local_modules: RefCell::new(Vec::new()),
1409             name_bindings: arena::TypedArena::new(),
1410             import_directives: arena::TypedArena::new(),
1411             name_resolutions: arena::TypedArena::new(),
1412             invocation_data: arena::TypedArena::new(),
1413             legacy_bindings: arena::TypedArena::new(),
1414         }
1415     }
1416
1417     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1418         PerNS {
1419             type_ns: f(self, TypeNS),
1420             value_ns: f(self, ValueNS),
1421             macro_ns: match self.use_extern_macros {
1422                 true => Some(f(self, MacroNS)),
1423                 false => None,
1424             },
1425         }
1426     }
1427
1428     /// Entry point to crate resolution.
1429     pub fn resolve_crate(&mut self, krate: &Crate) {
1430         ImportResolver { resolver: self }.finalize_imports();
1431         self.current_module = self.graph_root;
1432         self.finalize_current_module_macro_resolutions();
1433         visit::walk_crate(self, krate);
1434
1435         check_unused::check_crate(self, krate);
1436         self.report_errors();
1437         self.crate_loader.postprocess(krate);
1438     }
1439
1440     fn new_module(
1441         &self,
1442         parent: Module<'a>,
1443         kind: ModuleKind,
1444         normal_ancestor_id: DefId,
1445         span: Span,
1446     ) -> Module<'a> {
1447         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id, span))
1448     }
1449
1450     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1451                   -> bool /* true if an error was reported */ {
1452         match binding.kind {
1453             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1454                     if !used.get() => {
1455                 used.set(true);
1456                 directive.used.set(true);
1457                 if legacy_self_import {
1458                     self.warn_legacy_self_import(directive);
1459                     return false;
1460                 }
1461                 self.used_imports.insert((directive.id, ns));
1462                 self.add_to_glob_map(directive.id, ident);
1463                 self.record_use(ident, ns, binding, span)
1464             }
1465             NameBindingKind::Import { .. } => false,
1466             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1467                 self.ambiguity_errors.push(AmbiguityError {
1468                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1469                 });
1470                 if legacy {
1471                     self.record_use(ident, ns, b1, span);
1472                 }
1473                 !legacy
1474             }
1475             _ => false
1476         }
1477     }
1478
1479     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1480         if self.make_glob_map {
1481             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1482         }
1483     }
1484
1485     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1486     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1487     /// `ident` in the first scope that defines it (or None if no scopes define it).
1488     ///
1489     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1490     /// the items are defined in the block. For example,
1491     /// ```rust
1492     /// fn f() {
1493     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1494     ///    let g = || {};
1495     ///    fn g() {}
1496     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1497     /// }
1498     /// ```
1499     ///
1500     /// Invariant: This must only be called during main resolution, not during
1501     /// import resolution.
1502     fn resolve_ident_in_lexical_scope(&mut self,
1503                                       mut ident: Ident,
1504                                       ns: Namespace,
1505                                       record_used: bool,
1506                                       path_span: Span)
1507                                       -> Option<LexicalScopeBinding<'a>> {
1508         if ns == TypeNS {
1509             ident = ident.unhygienize();
1510         }
1511
1512         // Walk backwards up the ribs in scope.
1513         for i in (0 .. self.ribs[ns].len()).rev() {
1514             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1515                 // The ident resolves to a type parameter or local variable.
1516                 return Some(LexicalScopeBinding::Def(
1517                     self.adjust_local_def(ns, i, def, record_used, path_span)
1518                 ));
1519             }
1520
1521             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1522                 let item = self.resolve_ident_in_module(module, ident, ns, false,
1523                                                         record_used, path_span);
1524                 if let Ok(binding) = item {
1525                     // The ident resolves to an item.
1526                     return Some(LexicalScopeBinding::Item(binding));
1527                 }
1528
1529                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1530                 } else if !module.no_implicit_prelude {
1531                     return self.prelude.and_then(|prelude| {
1532                         self.resolve_ident_in_module(prelude, ident, ns, false,
1533                                                      false, path_span).ok()
1534                     }).map(LexicalScopeBinding::Item)
1535                 } else {
1536                     return None;
1537                 }
1538             }
1539
1540             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1541                 // If an invocation of this macro created `ident`, give up on `ident`
1542                 // and switch to `ident`'s source from the macro definition.
1543                 let ctxt_data = ident.ctxt.data();
1544                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1545                     ident.ctxt = ctxt_data.prev_ctxt;
1546                 }
1547             }
1548         }
1549
1550         None
1551     }
1552
1553     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext, span: Span) -> Module<'a> {
1554         let mut ctxt_data = crate_var_ctxt.data();
1555         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1556             ctxt_data = ctxt_data.prev_ctxt.data();
1557         }
1558         let module = self.macro_def_scope(ctxt_data.outer_mark, span);
1559         if module.is_local() { self.graph_root } else { module }
1560     }
1561
1562     // AST resolution
1563     //
1564     // We maintain a list of value ribs and type ribs.
1565     //
1566     // Simultaneously, we keep track of the current position in the module
1567     // graph in the `current_module` pointer. When we go to resolve a name in
1568     // the value or type namespaces, we first look through all the ribs and
1569     // then query the module graph. When we resolve a name in the module
1570     // namespace, we can skip all the ribs (since nested modules are not
1571     // allowed within blocks in Rust) and jump straight to the current module
1572     // graph node.
1573     //
1574     // Named implementations are handled separately. When we find a method
1575     // call, we consult the module node to find all of the implementations in
1576     // scope. This information is lazily cached in the module node. We then
1577     // generate a fake "implementation scope" containing all the
1578     // implementations thus found, for compatibility with old resolve pass.
1579
1580     fn with_scope<F>(&mut self, id: NodeId, f: F)
1581         where F: FnOnce(&mut Resolver)
1582     {
1583         let id = self.definitions.local_def_id(id);
1584         let module = self.module_map.get(&id).cloned(); // clones a reference
1585         if let Some(module) = module {
1586             // Move down in the graph.
1587             let orig_module = replace(&mut self.current_module, module);
1588             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1589             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1590
1591             self.finalize_current_module_macro_resolutions();
1592             f(self);
1593
1594             self.current_module = orig_module;
1595             self.ribs[ValueNS].pop();
1596             self.ribs[TypeNS].pop();
1597         } else {
1598             f(self);
1599         }
1600     }
1601
1602     /// Searches the current set of local scopes for labels.
1603     /// Stops after meeting a closure.
1604     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1605         for rib in self.label_ribs.iter().rev() {
1606             match rib.kind {
1607                 NormalRibKind => {
1608                     // Continue
1609                 }
1610                 MacroDefinition(def) => {
1611                     // If an invocation of this macro created `ident`, give up on `ident`
1612                     // and switch to `ident`'s source from the macro definition.
1613                     let ctxt_data = ident.ctxt.data();
1614                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1615                         ident.ctxt = ctxt_data.prev_ctxt;
1616                     }
1617                 }
1618                 _ => {
1619                     // Do not resolve labels across function boundary
1620                     return None;
1621                 }
1622             }
1623             let result = rib.bindings.get(&ident).cloned();
1624             if result.is_some() {
1625                 return result;
1626             }
1627         }
1628         None
1629     }
1630
1631     fn resolve_item(&mut self, item: &Item) {
1632         let name = item.ident.name;
1633
1634         debug!("(resolving item) resolving {}", name);
1635
1636         self.check_proc_macro_attrs(&item.attrs);
1637
1638         match item.node {
1639             ItemKind::Enum(_, ref generics) |
1640             ItemKind::Ty(_, ref generics) |
1641             ItemKind::Struct(_, ref generics) |
1642             ItemKind::Union(_, ref generics) |
1643             ItemKind::Fn(.., ref generics, _) => {
1644                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1645                                              |this| visit::walk_item(this, item));
1646             }
1647
1648             ItemKind::DefaultImpl(_, ref trait_ref) => {
1649                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1650                     // Resolve type arguments in trait path
1651                     visit::walk_trait_ref(this, trait_ref);
1652                 });
1653             }
1654             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1655                 self.resolve_implementation(generics,
1656                                             opt_trait_ref,
1657                                             &self_type,
1658                                             item.id,
1659                                             impl_items),
1660
1661             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1662                 // Create a new rib for the trait-wide type parameters.
1663                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1664                     let local_def_id = this.definitions.local_def_id(item.id);
1665                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1666                         this.visit_generics(generics);
1667                         walk_list!(this, visit_ty_param_bound, bounds);
1668
1669                         for trait_item in trait_items {
1670                             this.check_proc_macro_attrs(&trait_item.attrs);
1671
1672                             match trait_item.node {
1673                                 TraitItemKind::Const(_, ref default) => {
1674                                     // Only impose the restrictions of
1675                                     // ConstRibKind if there's an actual constant
1676                                     // expression in a provided default.
1677                                     if default.is_some() {
1678                                         this.with_constant_rib(|this| {
1679                                             visit::walk_trait_item(this, trait_item)
1680                                         });
1681                                     } else {
1682                                         visit::walk_trait_item(this, trait_item)
1683                                     }
1684                                 }
1685                                 TraitItemKind::Method(ref sig, _) => {
1686                                     let type_parameters =
1687                                         HasTypeParameters(&sig.generics,
1688                                                           MethodRibKind(!sig.decl.has_self()));
1689                                     this.with_type_parameter_rib(type_parameters, |this| {
1690                                         visit::walk_trait_item(this, trait_item)
1691                                     });
1692                                 }
1693                                 TraitItemKind::Type(..) => {
1694                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1695                                         visit::walk_trait_item(this, trait_item)
1696                                     });
1697                                 }
1698                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1699                             };
1700                         }
1701                     });
1702                 });
1703             }
1704
1705             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1706                 self.with_scope(item.id, |this| {
1707                     visit::walk_item(this, item);
1708                 });
1709             }
1710
1711             ItemKind::Const(..) | ItemKind::Static(..) => {
1712                 self.with_constant_rib(|this| {
1713                     visit::walk_item(this, item);
1714                 });
1715             }
1716
1717             ItemKind::Use(ref view_path) => {
1718                 match view_path.node {
1719                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1720                         // Resolve prefix of an import with empty braces (issue #28388).
1721                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1722                     }
1723                     _ => {}
1724                 }
1725             }
1726
1727             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(_)=> {
1728                 // do nothing, these are just around to be encoded
1729             }
1730
1731             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1732         }
1733     }
1734
1735     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1736         where F: FnOnce(&mut Resolver)
1737     {
1738         match type_parameters {
1739             HasTypeParameters(generics, rib_kind) => {
1740                 let mut function_type_rib = Rib::new(rib_kind);
1741                 let mut seen_bindings = FxHashMap();
1742                 for type_parameter in &generics.ty_params {
1743                     let name = type_parameter.ident.name;
1744                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1745
1746                     if seen_bindings.contains_key(&name) {
1747                         let span = seen_bindings.get(&name).unwrap();
1748                         resolve_error(self,
1749                                       type_parameter.span,
1750                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1751                                                                                           span));
1752                     }
1753                     seen_bindings.entry(name).or_insert(type_parameter.span);
1754
1755                     // plain insert (no renaming)
1756                     let def_id = self.definitions.local_def_id(type_parameter.id);
1757                     let def = Def::TyParam(def_id);
1758                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1759                     self.record_def(type_parameter.id, PathResolution::new(def));
1760                 }
1761                 self.ribs[TypeNS].push(function_type_rib);
1762             }
1763
1764             NoTypeParameters => {
1765                 // Nothing to do.
1766             }
1767         }
1768
1769         f(self);
1770
1771         if let HasTypeParameters(..) = type_parameters {
1772             self.ribs[TypeNS].pop();
1773         }
1774     }
1775
1776     fn with_label_rib<F>(&mut self, f: F)
1777         where F: FnOnce(&mut Resolver)
1778     {
1779         self.label_ribs.push(Rib::new(NormalRibKind));
1780         f(self);
1781         self.label_ribs.pop();
1782     }
1783
1784     fn with_constant_rib<F>(&mut self, f: F)
1785         where F: FnOnce(&mut Resolver)
1786     {
1787         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1788         self.ribs[TypeNS].push(Rib::new(ConstantItemRibKind));
1789         f(self);
1790         self.ribs[TypeNS].pop();
1791         self.ribs[ValueNS].pop();
1792     }
1793
1794     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1795         where F: FnOnce(&mut Resolver) -> T
1796     {
1797         // Handle nested impls (inside fn bodies)
1798         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1799         let result = f(self);
1800         self.current_self_type = previous_value;
1801         result
1802     }
1803
1804     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1805         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1806     {
1807         let mut new_val = None;
1808         let mut new_id = None;
1809         if let Some(trait_ref) = opt_trait_ref {
1810             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1811                                               &trait_ref.path, PathSource::Trait).base_def();
1812             if def != Def::Err {
1813                 new_val = Some((def.def_id(), trait_ref.clone()));
1814                 new_id = Some(def.def_id());
1815             }
1816         }
1817         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1818         let result = f(self, new_id);
1819         self.current_trait_ref = original_trait_ref;
1820         result
1821     }
1822
1823     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1824         where F: FnOnce(&mut Resolver)
1825     {
1826         let mut self_type_rib = Rib::new(NormalRibKind);
1827
1828         // plain insert (no renaming, types are not currently hygienic....)
1829         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1830         self.ribs[TypeNS].push(self_type_rib);
1831         f(self);
1832         self.ribs[TypeNS].pop();
1833     }
1834
1835     fn resolve_implementation(&mut self,
1836                               generics: &Generics,
1837                               opt_trait_reference: &Option<TraitRef>,
1838                               self_type: &Ty,
1839                               item_id: NodeId,
1840                               impl_items: &[ImplItem]) {
1841         // If applicable, create a rib for the type parameters.
1842         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1843             // Dummy self type for better errors if `Self` is used in the trait path.
1844             this.with_self_rib(Def::SelfTy(None, None), |this| {
1845                 // Resolve the trait reference, if necessary.
1846                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1847                     let item_def_id = this.definitions.local_def_id(item_id);
1848                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1849                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1850                             // Resolve type arguments in trait path
1851                             visit::walk_trait_ref(this, trait_ref);
1852                         }
1853                         // Resolve the self type.
1854                         this.visit_ty(self_type);
1855                         // Resolve the type parameters.
1856                         this.visit_generics(generics);
1857                         this.with_current_self_type(self_type, |this| {
1858                             for impl_item in impl_items {
1859                                 this.check_proc_macro_attrs(&impl_item.attrs);
1860                                 this.resolve_visibility(&impl_item.vis);
1861                                 match impl_item.node {
1862                                     ImplItemKind::Const(..) => {
1863                                         // If this is a trait impl, ensure the const
1864                                         // exists in trait
1865                                         this.check_trait_item(impl_item.ident.name,
1866                                                             ValueNS,
1867                                                             impl_item.span,
1868                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1869                                         visit::walk_impl_item(this, impl_item);
1870                                     }
1871                                     ImplItemKind::Method(ref sig, _) => {
1872                                         // If this is a trait impl, ensure the method
1873                                         // exists in trait
1874                                         this.check_trait_item(impl_item.ident.name,
1875                                                             ValueNS,
1876                                                             impl_item.span,
1877                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1878
1879                                         // We also need a new scope for the method-
1880                                         // specific type parameters.
1881                                         let type_parameters =
1882                                             HasTypeParameters(&sig.generics,
1883                                                             MethodRibKind(!sig.decl.has_self()));
1884                                         this.with_type_parameter_rib(type_parameters, |this| {
1885                                             visit::walk_impl_item(this, impl_item);
1886                                         });
1887                                     }
1888                                     ImplItemKind::Type(ref ty) => {
1889                                         // If this is a trait impl, ensure the type
1890                                         // exists in trait
1891                                         this.check_trait_item(impl_item.ident.name,
1892                                                             TypeNS,
1893                                                             impl_item.span,
1894                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1895
1896                                         this.visit_ty(ty);
1897                                     }
1898                                     ImplItemKind::Macro(_) =>
1899                                         panic!("unexpanded macro in resolve!"),
1900                                 }
1901                             }
1902                         });
1903                     });
1904                 });
1905             });
1906         });
1907     }
1908
1909     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1910         where F: FnOnce(Name, &str) -> ResolutionError
1911     {
1912         // If there is a TraitRef in scope for an impl, then the method must be in the
1913         // trait.
1914         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1915             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1916                 let path_str = path_names_to_string(&trait_ref.path);
1917                 resolve_error(self, span, err(name, &path_str));
1918             }
1919         }
1920     }
1921
1922     fn resolve_local(&mut self, local: &Local) {
1923         // Resolve the type.
1924         walk_list!(self, visit_ty, &local.ty);
1925
1926         // Resolve the initializer.
1927         walk_list!(self, visit_expr, &local.init);
1928
1929         // Resolve the pattern.
1930         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1931     }
1932
1933     // build a map from pattern identifiers to binding-info's.
1934     // this is done hygienically. This could arise for a macro
1935     // that expands into an or-pattern where one 'x' was from the
1936     // user and one 'x' came from the macro.
1937     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1938         let mut binding_map = FxHashMap();
1939
1940         pat.walk(&mut |pat| {
1941             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1942                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1943                     Some(Def::Local(..)) => true,
1944                     _ => false,
1945                 } {
1946                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1947                     binding_map.insert(ident.node, binding_info);
1948                 }
1949             }
1950             true
1951         });
1952
1953         binding_map
1954     }
1955
1956     // check that all of the arms in an or-pattern have exactly the
1957     // same set of bindings, with the same binding modes for each.
1958     fn check_consistent_bindings(&mut self, arm: &Arm) {
1959         if arm.pats.is_empty() {
1960             return;
1961         }
1962
1963         let mut missing_vars = FxHashMap();
1964         let mut inconsistent_vars = FxHashMap();
1965         for (i, p) in arm.pats.iter().enumerate() {
1966             let map_i = self.binding_mode_map(&p);
1967
1968             for (j, q) in arm.pats.iter().enumerate() {
1969                 if i == j {
1970                     continue;
1971                 }
1972
1973                 let map_j = self.binding_mode_map(&q);
1974                 for (&key, &binding_i) in &map_i {
1975                     if map_j.len() == 0 {                   // Account for missing bindings when
1976                         let binding_error = missing_vars    // map_j has none.
1977                             .entry(key.name)
1978                             .or_insert(BindingError {
1979                                 name: key.name,
1980                                 origin: BTreeSet::new(),
1981                                 target: BTreeSet::new(),
1982                             });
1983                         binding_error.origin.insert(binding_i.span);
1984                         binding_error.target.insert(q.span);
1985                     }
1986                     for (&key_j, &binding_j) in &map_j {
1987                         match map_i.get(&key_j) {
1988                             None => {  // missing binding
1989                                 let binding_error = missing_vars
1990                                     .entry(key_j.name)
1991                                     .or_insert(BindingError {
1992                                         name: key_j.name,
1993                                         origin: BTreeSet::new(),
1994                                         target: BTreeSet::new(),
1995                                     });
1996                                 binding_error.origin.insert(binding_j.span);
1997                                 binding_error.target.insert(p.span);
1998                             }
1999                             Some(binding_i) => {  // check consistent binding
2000                                 if binding_i.binding_mode != binding_j.binding_mode {
2001                                     inconsistent_vars
2002                                         .entry(key.name)
2003                                         .or_insert((binding_j.span, binding_i.span));
2004                                 }
2005                             }
2006                         }
2007                     }
2008                 }
2009             }
2010         }
2011         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
2012         missing_vars.sort();
2013         for (_, v) in missing_vars {
2014             resolve_error(self,
2015                           *v.origin.iter().next().unwrap(),
2016                           ResolutionError::VariableNotBoundInPattern(v));
2017         }
2018         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2019         inconsistent_vars.sort();
2020         for (name, v) in inconsistent_vars {
2021             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2022         }
2023     }
2024
2025     fn resolve_arm(&mut self, arm: &Arm) {
2026         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2027
2028         let mut bindings_list = FxHashMap();
2029         for pattern in &arm.pats {
2030             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2031         }
2032
2033         // This has to happen *after* we determine which
2034         // pat_idents are variants
2035         self.check_consistent_bindings(arm);
2036
2037         walk_list!(self, visit_expr, &arm.guard);
2038         self.visit_expr(&arm.body);
2039
2040         self.ribs[ValueNS].pop();
2041     }
2042
2043     fn resolve_block(&mut self, block: &Block) {
2044         debug!("(resolving block) entering block");
2045         // Move down in the graph, if there's an anonymous module rooted here.
2046         let orig_module = self.current_module;
2047         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2048
2049         let mut num_macro_definition_ribs = 0;
2050         if let Some(anonymous_module) = anonymous_module {
2051             debug!("(resolving block) found anonymous module, moving down");
2052             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2053             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2054             self.current_module = anonymous_module;
2055             self.finalize_current_module_macro_resolutions();
2056         } else {
2057             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2058         }
2059
2060         // Descend into the block.
2061         for stmt in &block.stmts {
2062             if let ast::StmtKind::Item(ref item) = stmt.node {
2063                 if let ast::ItemKind::MacroDef(..) = item.node {
2064                     num_macro_definition_ribs += 1;
2065                     let def = self.definitions.local_def_id(item.id);
2066                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2067                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2068                 }
2069             }
2070
2071             self.visit_stmt(stmt);
2072         }
2073
2074         // Move back up.
2075         self.current_module = orig_module;
2076         for _ in 0 .. num_macro_definition_ribs {
2077             self.ribs[ValueNS].pop();
2078             self.label_ribs.pop();
2079         }
2080         self.ribs[ValueNS].pop();
2081         if let Some(_) = anonymous_module {
2082             self.ribs[TypeNS].pop();
2083         }
2084         debug!("(resolving block) leaving block");
2085     }
2086
2087     fn fresh_binding(&mut self,
2088                      ident: &SpannedIdent,
2089                      pat_id: NodeId,
2090                      outer_pat_id: NodeId,
2091                      pat_src: PatternSource,
2092                      bindings: &mut FxHashMap<Ident, NodeId>)
2093                      -> PathResolution {
2094         // Add the binding to the local ribs, if it
2095         // doesn't already exist in the bindings map. (We
2096         // must not add it if it's in the bindings map
2097         // because that breaks the assumptions later
2098         // passes make about or-patterns.)
2099         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2100         match bindings.get(&ident.node).cloned() {
2101             Some(id) if id == outer_pat_id => {
2102                 // `Variant(a, a)`, error
2103                 resolve_error(
2104                     self,
2105                     ident.span,
2106                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2107                         &ident.node.name.as_str())
2108                 );
2109             }
2110             Some(..) if pat_src == PatternSource::FnParam => {
2111                 // `fn f(a: u8, a: u8)`, error
2112                 resolve_error(
2113                     self,
2114                     ident.span,
2115                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2116                         &ident.node.name.as_str())
2117                 );
2118             }
2119             Some(..) if pat_src == PatternSource::Match => {
2120                 // `Variant1(a) | Variant2(a)`, ok
2121                 // Reuse definition from the first `a`.
2122                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2123             }
2124             Some(..) => {
2125                 span_bug!(ident.span, "two bindings with the same name from \
2126                                        unexpected pattern source {:?}", pat_src);
2127             }
2128             None => {
2129                 // A completely fresh binding, add to the lists if it's valid.
2130                 if ident.node.name != keywords::Invalid.name() {
2131                     bindings.insert(ident.node, outer_pat_id);
2132                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2133                 }
2134             }
2135         }
2136
2137         PathResolution::new(def)
2138     }
2139
2140     fn resolve_pattern(&mut self,
2141                        pat: &Pat,
2142                        pat_src: PatternSource,
2143                        // Maps idents to the node ID for the
2144                        // outermost pattern that binds them.
2145                        bindings: &mut FxHashMap<Ident, NodeId>) {
2146         // Visit all direct subpatterns of this pattern.
2147         let outer_pat_id = pat.id;
2148         pat.walk(&mut |pat| {
2149             match pat.node {
2150                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2151                     // First try to resolve the identifier as some existing
2152                     // entity, then fall back to a fresh binding.
2153                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS,
2154                                                                       false, pat.span)
2155                                       .and_then(LexicalScopeBinding::item);
2156                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2157                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2158                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2159                         match def {
2160                             Def::StructCtor(_, CtorKind::Const) |
2161                             Def::VariantCtor(_, CtorKind::Const) |
2162                             Def::Const(..) if !always_binding => {
2163                                 // A unit struct/variant or constant pattern.
2164                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2165                                 Some(PathResolution::new(def))
2166                             }
2167                             Def::StructCtor(..) | Def::VariantCtor(..) |
2168                             Def::Const(..) | Def::Static(..) => {
2169                                 // A fresh binding that shadows something unacceptable.
2170                                 resolve_error(
2171                                     self,
2172                                     ident.span,
2173                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2174                                         pat_src.descr(), ident.node.name, binding.unwrap())
2175                                 );
2176                                 None
2177                             }
2178                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2179                                 // These entities are explicitly allowed
2180                                 // to be shadowed by fresh bindings.
2181                                 None
2182                             }
2183                             def => {
2184                                 span_bug!(ident.span, "unexpected definition for an \
2185                                                        identifier in pattern: {:?}", def);
2186                             }
2187                         }
2188                     }).unwrap_or_else(|| {
2189                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2190                     });
2191
2192                     self.record_def(pat.id, resolution);
2193                 }
2194
2195                 PatKind::TupleStruct(ref path, ..) => {
2196                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2197                 }
2198
2199                 PatKind::Path(ref qself, ref path) => {
2200                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2201                 }
2202
2203                 PatKind::Struct(ref path, ..) => {
2204                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2205                 }
2206
2207                 _ => {}
2208             }
2209             true
2210         });
2211
2212         visit::walk_pat(self, pat);
2213     }
2214
2215     // High-level and context dependent path resolution routine.
2216     // Resolves the path and records the resolution into definition map.
2217     // If resolution fails tries several techniques to find likely
2218     // resolution candidates, suggest imports or other help, and report
2219     // errors in user friendly way.
2220     fn smart_resolve_path(&mut self,
2221                           id: NodeId,
2222                           qself: Option<&QSelf>,
2223                           path: &Path,
2224                           source: PathSource)
2225                           -> PathResolution {
2226         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2227         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2228         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2229     }
2230
2231     fn smart_resolve_path_fragment(&mut self,
2232                                    id: NodeId,
2233                                    qself: Option<&QSelf>,
2234                                    path: &[Ident],
2235                                    span: Span,
2236                                    ident_span: Span,
2237                                    source: PathSource)
2238                                    -> PathResolution {
2239         let ns = source.namespace();
2240         let is_expected = &|def| source.is_expected(def);
2241         let is_enum_variant = &|def| if let Def::Variant(..) = def { true } else { false };
2242
2243         // Base error is amended with one short label and possibly some longer helps/notes.
2244         let report_errors = |this: &mut Self, def: Option<Def>| {
2245             // Make the base error.
2246             let expected = source.descr_expected();
2247             let path_str = names_to_string(path);
2248             let code = source.error_code(def.is_some());
2249             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2250                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2251                  format!("not a {}", expected), span)
2252             } else {
2253                 let item_str = path[path.len() - 1];
2254                 let (mod_prefix, mod_str) = if path.len() == 1 {
2255                     (format!(""), format!("this scope"))
2256                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2257                     (format!(""), format!("the crate root"))
2258                 } else {
2259                     let mod_path = &path[..path.len() - 1];
2260                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), false, span) {
2261                         PathResult::Module(module) => module.def(),
2262                         _ => None,
2263                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2264                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2265                 };
2266                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2267                  format!("not found in {}", mod_str), ident_span)
2268             };
2269             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2270
2271             // Emit special messages for unresolved `Self` and `self`.
2272             if is_self_type(path, ns) {
2273                 __diagnostic_used!(E0411);
2274                 err.code("E0411".into());
2275                 err.span_label(span, "`Self` is only available in traits and impls");
2276                 return err;
2277             }
2278             if is_self_value(path, ns) {
2279                 __diagnostic_used!(E0424);
2280                 err.code("E0424".into());
2281                 err.span_label(span, format!("`self` value is only available in \
2282                                                methods with `self` parameter"));
2283                 return err;
2284             }
2285
2286             // Try to lookup the name in more relaxed fashion for better error reporting.
2287             let name = path.last().unwrap().name;
2288             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2289             if !candidates.is_empty() {
2290                 let mut module_span = this.current_module.span;
2291                 module_span.hi = module_span.lo;
2292                 // Report import candidates as help and proceed searching for labels.
2293                 show_candidates(&mut err, module_span, &candidates, def.is_some());
2294             } else if is_expected(Def::Enum(DefId::local(CRATE_DEF_INDEX))) {
2295                 let enum_candidates = this.lookup_import_candidates(name, ns, is_enum_variant);
2296                 let mut enum_candidates = enum_candidates.iter()
2297                     .map(|suggestion| import_candidate_to_paths(&suggestion)).collect::<Vec<_>>();
2298                 enum_candidates.sort();
2299                 for (sp, variant_path, enum_path) in enum_candidates {
2300                     let msg = format!("there is an enum variant `{}`, did you mean to use `{}`?",
2301                                       variant_path,
2302                                       enum_path);
2303                     if sp == DUMMY_SP {
2304                         err.help(&msg);
2305                     } else {
2306                         err.span_help(sp, &msg);
2307                     }
2308                 }
2309             }
2310             if path.len() == 1 && this.self_type_is_available(span) {
2311                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2312                     let self_is_available = this.self_value_is_available(path[0].ctxt, span);
2313                     match candidate {
2314                         AssocSuggestion::Field => {
2315                             err.span_label(span, format!("did you mean `self.{}`?", path_str));
2316                             if !self_is_available {
2317                                 err.span_label(span, format!("`self` value is only available in \
2318                                                                methods with `self` parameter"));
2319                             }
2320                         }
2321                         AssocSuggestion::MethodWithSelf if self_is_available => {
2322                             err.span_label(span, format!("did you mean `self.{}(...)`?",
2323                                                            path_str));
2324                         }
2325                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2326                             err.span_label(span, format!("did you mean `Self::{}`?", path_str));
2327                         }
2328                     }
2329                     return err;
2330                 }
2331             }
2332
2333             let mut levenshtein_worked = false;
2334
2335             // Try Levenshtein.
2336             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected, span) {
2337                 err.span_label(ident_span, format!("did you mean `{}`?", candidate));
2338                 levenshtein_worked = true;
2339             }
2340
2341             // Try context dependent help if relaxed lookup didn't work.
2342             if let Some(def) = def {
2343                 match (def, source) {
2344                     (Def::Macro(..), _) => {
2345                         err.span_label(span, format!("did you mean `{}!(...)`?", path_str));
2346                         return err;
2347                     }
2348                     (Def::TyAlias(..), PathSource::Trait) => {
2349                         err.span_label(span, "type aliases cannot be used for traits");
2350                         return err;
2351                     }
2352                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2353                         ExprKind::Field(_, ident) => {
2354                             err.span_label(parent.span, format!("did you mean `{}::{}`?",
2355                                                                  path_str, ident.node));
2356                             return err;
2357                         }
2358                         ExprKind::MethodCall(ident, ..) => {
2359                             err.span_label(parent.span, format!("did you mean `{}::{}(...)`?",
2360                                                                  path_str, ident.node));
2361                             return err;
2362                         }
2363                         _ => {}
2364                     },
2365                     _ if ns == ValueNS && is_struct_like(def) => {
2366                         if let Def::Struct(def_id) = def {
2367                             if let Some((ctor_def, ctor_vis))
2368                                     = this.struct_constructors.get(&def_id).cloned() {
2369                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2370                                     err.span_label(span, format!("constructor is not visible \
2371                                                                    here due to private fields"));
2372                                 }
2373                             }
2374                         }
2375                         err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?",
2376                                                        path_str));
2377                         return err;
2378                     }
2379                     _ => {}
2380                 }
2381             }
2382
2383             // Fallback label.
2384             if !levenshtein_worked {
2385                 err.span_label(base_span, fallback_label);
2386             }
2387             err
2388         };
2389         let report_errors = |this: &mut Self, def: Option<Def>| {
2390             report_errors(this, def).emit();
2391             err_path_resolution()
2392         };
2393
2394         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2395                                                            source.defer_to_typeck(),
2396                                                            source.global_by_default()) {
2397             Some(resolution) if resolution.unresolved_segments() == 0 => {
2398                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2399                     resolution
2400                 } else {
2401                     // Add a temporary hack to smooth the transition to new struct ctor
2402                     // visibility rules. See #38932 for more details.
2403                     let mut res = None;
2404                     if let Def::Struct(def_id) = resolution.base_def() {
2405                         if let Some((ctor_def, ctor_vis))
2406                                 = self.struct_constructors.get(&def_id).cloned() {
2407                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2408                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2409                                 self.session.add_lint(lint, id, span,
2410                                     "private struct constructors are not usable through \
2411                                      reexports in outer modules".to_string());
2412                                 res = Some(PathResolution::new(ctor_def));
2413                             }
2414                         }
2415                     }
2416
2417                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2418                 }
2419             }
2420             Some(resolution) if source.defer_to_typeck() => {
2421                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2422                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2423                 // it needs to be added to the trait map.
2424                 if ns == ValueNS {
2425                     let item_name = path.last().unwrap().name;
2426                     let traits = self.get_traits_containing_item(item_name, ns);
2427                     self.trait_map.insert(id, traits);
2428                 }
2429                 resolution
2430             }
2431             _ => report_errors(self, None)
2432         };
2433
2434         if let PathSource::TraitItem(..) = source {} else {
2435             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2436             self.record_def(id, resolution);
2437         }
2438         resolution
2439     }
2440
2441     fn self_type_is_available(&mut self, span: Span) -> bool {
2442         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(),
2443                                                           TypeNS, false, span);
2444         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2445     }
2446
2447     fn self_value_is_available(&mut self, ctxt: SyntaxContext, span: Span) -> bool {
2448         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2449         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, false, span);
2450         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2451     }
2452
2453     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2454     fn resolve_qpath_anywhere(&mut self,
2455                               id: NodeId,
2456                               qself: Option<&QSelf>,
2457                               path: &[Ident],
2458                               primary_ns: Namespace,
2459                               span: Span,
2460                               defer_to_typeck: bool,
2461                               global_by_default: bool)
2462                               -> Option<PathResolution> {
2463         let mut fin_res = None;
2464         // FIXME: can't resolve paths in macro namespace yet, macros are
2465         // processed by the little special hack below.
2466         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2467             if i == 0 || ns != primary_ns {
2468                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2469                     // If defer_to_typeck, then resolution > no resolution,
2470                     // otherwise full resolution > partial resolution > no resolution.
2471                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2472                         return Some(res),
2473                     res => if fin_res.is_none() { fin_res = res },
2474                 };
2475             }
2476         }
2477         let is_global = self.global_macros.get(&path[0].name).cloned()
2478             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2479         if primary_ns != MacroNS && (is_global || self.macro_names.contains(&path[0].name)) {
2480             // Return some dummy definition, it's enough for error reporting.
2481             return Some(
2482                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2483             );
2484         }
2485         fin_res
2486     }
2487
2488     /// Handles paths that may refer to associated items.
2489     fn resolve_qpath(&mut self,
2490                      id: NodeId,
2491                      qself: Option<&QSelf>,
2492                      path: &[Ident],
2493                      ns: Namespace,
2494                      span: Span,
2495                      global_by_default: bool)
2496                      -> Option<PathResolution> {
2497         if let Some(qself) = qself {
2498             if qself.position == 0 {
2499                 // FIXME: Create some fake resolution that can't possibly be a type.
2500                 return Some(PathResolution::with_unresolved_segments(
2501                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2502                 ));
2503             }
2504             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2505             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2506             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2507                                                        span, span, PathSource::TraitItem(ns));
2508             return Some(PathResolution::with_unresolved_segments(
2509                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2510             ));
2511         }
2512
2513         let result = match self.resolve_path(&path, Some(ns), true, span) {
2514             PathResult::NonModule(path_res) => path_res,
2515             PathResult::Module(module) if !module.is_normal() => {
2516                 PathResolution::new(module.def().unwrap())
2517             }
2518             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2519             // don't report an error right away, but try to fallback to a primitive type.
2520             // So, we are still able to successfully resolve something like
2521             //
2522             // use std::u8; // bring module u8 in scope
2523             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2524             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2525             //                     // not to non-existent std::u8::max_value
2526             // }
2527             //
2528             // Such behavior is required for backward compatibility.
2529             // The same fallback is used when `a` resolves to nothing.
2530             PathResult::Module(..) | PathResult::Failed(..)
2531                     if (ns == TypeNS || path.len() > 1) &&
2532                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2533                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2534                 match prim {
2535                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2536                         if !self.session.features.borrow().i128_type {
2537                             emit_feature_err(&self.session.parse_sess,
2538                                                 "i128_type", span, GateIssue::Language,
2539                                                 "128-bit type is unstable");
2540
2541                         }
2542                     }
2543                     _ => {}
2544                 }
2545                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2546             }
2547             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2548             PathResult::Failed(msg, false) => {
2549                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2550                 err_path_resolution()
2551             }
2552             PathResult::Failed(..) => return None,
2553             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2554         };
2555
2556         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2557            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2558             let unqualified_result = {
2559                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), false, span) {
2560                     PathResult::NonModule(path_res) => path_res.base_def(),
2561                     PathResult::Module(module) => module.def().unwrap(),
2562                     _ => return Some(result),
2563                 }
2564             };
2565             if result.base_def() == unqualified_result {
2566                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2567                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2568             }
2569         }
2570
2571         Some(result)
2572     }
2573
2574     fn resolve_path(&mut self,
2575                     path: &[Ident],
2576                     opt_ns: Option<Namespace>, // `None` indicates a module path
2577                     record_used: bool,
2578                     path_span: Span)
2579                     -> PathResult<'a> {
2580         let mut module = None;
2581         let mut allow_super = true;
2582
2583         for (i, &ident) in path.iter().enumerate() {
2584             let is_last = i == path.len() - 1;
2585             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2586
2587             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2588                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2589                 continue
2590             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2591                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2592                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2593                 if let Some(parent) = self_module.parent {
2594                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2595                     continue
2596                 } else {
2597                     let msg = "There are too many initial `super`s.".to_string();
2598                     return PathResult::Failed(msg, false);
2599                 }
2600             }
2601             allow_super = false;
2602
2603             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2604                 module = Some(self.graph_root);
2605                 continue
2606             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2607                 module = Some(self.resolve_crate_var(ident.ctxt, DUMMY_SP));
2608                 continue
2609             }
2610
2611             let binding = if let Some(module) = module {
2612                 self.resolve_ident_in_module(module, ident, ns, false, record_used, path_span)
2613             } else if opt_ns == Some(MacroNS) {
2614                 self.resolve_lexical_macro_path_segment(ident, ns, record_used, path_span)
2615                     .map(MacroBinding::binding)
2616             } else {
2617                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used, path_span) {
2618                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2619                     Some(LexicalScopeBinding::Def(def))
2620                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2621                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2622                             def, path.len() - 1
2623                         ));
2624                     }
2625                     _ => Err(if record_used { Determined } else { Undetermined }),
2626                 }
2627             };
2628
2629             match binding {
2630                 Ok(binding) => {
2631                     let def = binding.def();
2632                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2633                     if let Some(next_module) = binding.module() {
2634                         module = Some(next_module);
2635                     } else if def == Def::Err {
2636                         return PathResult::NonModule(err_path_resolution());
2637                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2638                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2639                             def, path.len() - i - 1
2640                         ));
2641                     } else {
2642                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2643                     }
2644                 }
2645                 Err(Undetermined) => return PathResult::Indeterminate,
2646                 Err(Determined) => {
2647                     if let Some(module) = module {
2648                         if opt_ns.is_some() && !module.is_normal() {
2649                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2650                                 module.def().unwrap(), path.len() - i
2651                             ));
2652                         }
2653                     }
2654                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2655                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2656                         let mut candidates =
2657                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2658                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2659                         if let Some(candidate) = candidates.get(0) {
2660                             format!("Did you mean `{}`?", candidate.path)
2661                         } else {
2662                             format!("Maybe a missing `extern crate {};`?", ident)
2663                         }
2664                     } else if i == 0 {
2665                         format!("Use of undeclared type or module `{}`", ident)
2666                     } else {
2667                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2668                     };
2669                     return PathResult::Failed(msg, is_last);
2670                 }
2671             }
2672         }
2673
2674         PathResult::Module(module.unwrap_or(self.graph_root))
2675     }
2676
2677     // Resolve a local definition, potentially adjusting for closures.
2678     fn adjust_local_def(&mut self,
2679                         ns: Namespace,
2680                         rib_index: usize,
2681                         mut def: Def,
2682                         record_used: bool,
2683                         span: Span) -> Def {
2684         let ribs = &self.ribs[ns][rib_index + 1..];
2685
2686         // An invalid forward use of a type parameter from a previous default.
2687         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2688             if record_used {
2689                 resolve_error(self, span,
2690                         ResolutionError::ForwardDeclaredTyParam);
2691             }
2692             assert_eq!(def, Def::Err);
2693             return Def::Err;
2694         }
2695
2696         match def {
2697             Def::Upvar(..) => {
2698                 span_bug!(span, "unexpected {:?} in bindings", def)
2699             }
2700             Def::Local(def_id) => {
2701                 for rib in ribs {
2702                     match rib.kind {
2703                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2704                         ForwardTyParamBanRibKind => {
2705                             // Nothing to do. Continue.
2706                         }
2707                         ClosureRibKind(function_id) => {
2708                             let prev_def = def;
2709                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2710
2711                             let seen = self.freevars_seen
2712                                            .entry(function_id)
2713                                            .or_insert_with(|| NodeMap());
2714                             if let Some(&index) = seen.get(&node_id) {
2715                                 def = Def::Upvar(def_id, index, function_id);
2716                                 continue;
2717                             }
2718                             let vec = self.freevars
2719                                           .entry(function_id)
2720                                           .or_insert_with(|| vec![]);
2721                             let depth = vec.len();
2722                             def = Def::Upvar(def_id, depth, function_id);
2723
2724                             if record_used {
2725                                 vec.push(Freevar {
2726                                     def: prev_def,
2727                                     span: span,
2728                                 });
2729                                 seen.insert(node_id, depth);
2730                             }
2731                         }
2732                         ItemRibKind | MethodRibKind(_) => {
2733                             // This was an attempt to access an upvar inside a
2734                             // named function item. This is not allowed, so we
2735                             // report an error.
2736                             if record_used {
2737                                 resolve_error(self, span,
2738                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2739                             }
2740                             return Def::Err;
2741                         }
2742                         ConstantItemRibKind => {
2743                             // Still doesn't deal with upvars
2744                             if record_used {
2745                                 resolve_error(self, span,
2746                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2747                             }
2748                             return Def::Err;
2749                         }
2750                     }
2751                 }
2752             }
2753             Def::TyParam(..) | Def::SelfTy(..) => {
2754                 for rib in ribs {
2755                     match rib.kind {
2756                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2757                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind => {
2758                             // Nothing to do. Continue.
2759                         }
2760                         ItemRibKind => {
2761                             // This was an attempt to use a type parameter outside
2762                             // its scope.
2763                             if record_used {
2764                                 resolve_error(self, span,
2765                                               ResolutionError::TypeParametersFromOuterFunction);
2766                             }
2767                             return Def::Err;
2768                         }
2769                         ConstantItemRibKind => {
2770                             // see #9186
2771                             if record_used {
2772                                 resolve_error(self, span,
2773                                               ResolutionError::OuterTypeParameterContext);
2774                             }
2775                             return Def::Err;
2776                         }
2777                     }
2778                 }
2779             }
2780             _ => {}
2781         }
2782         return def;
2783     }
2784
2785     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2786     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2787     // FIXME #34673: This needs testing.
2788     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2789         where F: FnOnce(&mut Resolver<'a>) -> T,
2790     {
2791         self.with_empty_ribs(|this| {
2792             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2793             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2794             f(this)
2795         })
2796     }
2797
2798     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2799         where F: FnOnce(&mut Resolver<'a>) -> T,
2800     {
2801         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2802         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2803
2804         let result = f(self);
2805         self.ribs = ribs;
2806         self.label_ribs = label_ribs;
2807         result
2808     }
2809
2810     fn lookup_assoc_candidate<FilterFn>(&mut self,
2811                                         name: Name,
2812                                         ns: Namespace,
2813                                         filter_fn: FilterFn)
2814                                         -> Option<AssocSuggestion>
2815         where FilterFn: Fn(Def) -> bool
2816     {
2817         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2818             match t.node {
2819                 TyKind::Path(None, _) => Some(t.id),
2820                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2821                 // This doesn't handle the remaining `Ty` variants as they are not
2822                 // that commonly the self_type, it might be interesting to provide
2823                 // support for those in future.
2824                 _ => None,
2825             }
2826         }
2827
2828         // Fields are generally expected in the same contexts as locals.
2829         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2830             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2831                 // Look for a field with the same name in the current self_type.
2832                 if let Some(resolution) = self.def_map.get(&node_id) {
2833                     match resolution.base_def() {
2834                         Def::Struct(did) | Def::Union(did)
2835                                 if resolution.unresolved_segments() == 0 => {
2836                             if let Some(field_names) = self.field_names.get(&did) {
2837                                 if field_names.iter().any(|&field_name| name == field_name) {
2838                                     return Some(AssocSuggestion::Field);
2839                                 }
2840                             }
2841                         }
2842                         _ => {}
2843                     }
2844                 }
2845             }
2846         }
2847
2848         // Look for associated items in the current trait.
2849         if let Some((trait_did, _)) = self.current_trait_ref {
2850             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2851                 if filter_fn(def) {
2852                     return Some(if has_self {
2853                         AssocSuggestion::MethodWithSelf
2854                     } else {
2855                         AssocSuggestion::AssocItem
2856                     });
2857                 }
2858             }
2859         }
2860
2861         None
2862     }
2863
2864     fn lookup_typo_candidate<FilterFn>(&mut self,
2865                                        path: &[Ident],
2866                                        ns: Namespace,
2867                                        filter_fn: FilterFn,
2868                                        span: Span)
2869                                        -> Option<Symbol>
2870         where FilterFn: Fn(Def) -> bool
2871     {
2872         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2873             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2874                 if let Some(binding) = resolution.borrow().binding {
2875                     if filter_fn(binding.def()) {
2876                         names.push(ident.name);
2877                     }
2878                 }
2879             }
2880         };
2881
2882         let mut names = Vec::new();
2883         if path.len() == 1 {
2884             // Search in lexical scope.
2885             // Walk backwards up the ribs in scope and collect candidates.
2886             for rib in self.ribs[ns].iter().rev() {
2887                 // Locals and type parameters
2888                 for (ident, def) in &rib.bindings {
2889                     if filter_fn(*def) {
2890                         names.push(ident.name);
2891                     }
2892                 }
2893                 // Items in scope
2894                 if let ModuleRibKind(module) = rib.kind {
2895                     // Items from this module
2896                     add_module_candidates(module, &mut names);
2897
2898                     if let ModuleKind::Block(..) = module.kind {
2899                         // We can see through blocks
2900                     } else {
2901                         // Items from the prelude
2902                         if let Some(prelude) = self.prelude {
2903                             if !module.no_implicit_prelude {
2904                                 add_module_candidates(prelude, &mut names);
2905                             }
2906                         }
2907                         break;
2908                     }
2909                 }
2910             }
2911             // Add primitive types to the mix
2912             if filter_fn(Def::PrimTy(TyBool)) {
2913                 for (name, _) in &self.primitive_type_table.primitive_types {
2914                     names.push(*name);
2915                 }
2916             }
2917         } else {
2918             // Search in module.
2919             let mod_path = &path[..path.len() - 1];
2920             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS),
2921                                                                   false, span) {
2922                 add_module_candidates(module, &mut names);
2923             }
2924         }
2925
2926         let name = path[path.len() - 1].name;
2927         // Make sure error reporting is deterministic.
2928         names.sort_by_key(|name| name.as_str());
2929         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2930             Some(found) if found != name => Some(found),
2931             _ => None,
2932         }
2933     }
2934
2935     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2936         where F: FnOnce(&mut Resolver)
2937     {
2938         if let Some(label) = label {
2939             let def = Def::Label(id);
2940             self.with_label_rib(|this| {
2941                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2942                 f(this);
2943             });
2944         } else {
2945             f(self);
2946         }
2947     }
2948
2949     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2950         self.with_resolved_label(label, id, |this| this.visit_block(block));
2951     }
2952
2953     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2954         // First, record candidate traits for this expression if it could
2955         // result in the invocation of a method call.
2956
2957         self.record_candidate_traits_for_expr_if_necessary(expr);
2958
2959         // Next, resolve the node.
2960         match expr.node {
2961             ExprKind::Path(ref qself, ref path) => {
2962                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2963                 visit::walk_expr(self, expr);
2964             }
2965
2966             ExprKind::Struct(ref path, ..) => {
2967                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2968                 visit::walk_expr(self, expr);
2969             }
2970
2971             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2972                 match self.search_label(label.node) {
2973                     None => {
2974                         self.record_def(expr.id, err_path_resolution());
2975                         resolve_error(self,
2976                                       label.span,
2977                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2978                     }
2979                     Some(def @ Def::Label(_)) => {
2980                         // Since this def is a label, it is never read.
2981                         self.record_def(expr.id, PathResolution::new(def));
2982                     }
2983                     Some(_) => {
2984                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2985                     }
2986                 }
2987
2988                 // visit `break` argument if any
2989                 visit::walk_expr(self, expr);
2990             }
2991
2992             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2993                 self.visit_expr(subexpression);
2994
2995                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2996                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
2997                 self.visit_block(if_block);
2998                 self.ribs[ValueNS].pop();
2999
3000                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
3001             }
3002
3003             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3004
3005             ExprKind::While(ref subexpression, ref block, label) => {
3006                 self.with_resolved_label(label, expr.id, |this| {
3007                     this.visit_expr(subexpression);
3008                     this.visit_block(block);
3009                 });
3010             }
3011
3012             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
3013                 self.with_resolved_label(label, expr.id, |this| {
3014                     this.visit_expr(subexpression);
3015                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
3016                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
3017                     this.visit_block(block);
3018                     this.ribs[ValueNS].pop();
3019                 });
3020             }
3021
3022             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
3023                 self.visit_expr(subexpression);
3024                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3025                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
3026
3027                 self.resolve_labeled_block(label, expr.id, block);
3028
3029                 self.ribs[ValueNS].pop();
3030             }
3031
3032             // Equivalent to `visit::walk_expr` + passing some context to children.
3033             ExprKind::Field(ref subexpression, _) => {
3034                 self.resolve_expr(subexpression, Some(expr));
3035             }
3036             ExprKind::MethodCall(_, ref types, ref arguments) => {
3037                 let mut arguments = arguments.iter();
3038                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3039                 for argument in arguments {
3040                     self.resolve_expr(argument, None);
3041                 }
3042                 for ty in types.iter() {
3043                     self.visit_ty(ty);
3044                 }
3045             }
3046
3047             ExprKind::Repeat(ref element, ref count) => {
3048                 self.visit_expr(element);
3049                 self.with_constant_rib(|this| {
3050                     this.visit_expr(count);
3051                 });
3052             }
3053             ExprKind::Call(ref callee, ref arguments) => {
3054                 self.resolve_expr(callee, Some(expr));
3055                 for argument in arguments {
3056                     self.resolve_expr(argument, None);
3057                 }
3058             }
3059
3060             _ => {
3061                 visit::walk_expr(self, expr);
3062             }
3063         }
3064     }
3065
3066     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3067         match expr.node {
3068             ExprKind::Field(_, name) => {
3069                 // FIXME(#6890): Even though you can't treat a method like a
3070                 // field, we need to add any trait methods we find that match
3071                 // the field name so that we can do some nice error reporting
3072                 // later on in typeck.
3073                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3074                 self.trait_map.insert(expr.id, traits);
3075             }
3076             ExprKind::MethodCall(name, ..) => {
3077                 debug!("(recording candidate traits for expr) recording traits for {}",
3078                        expr.id);
3079                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3080                 self.trait_map.insert(expr.id, traits);
3081             }
3082             _ => {
3083                 // Nothing to do.
3084             }
3085         }
3086     }
3087
3088     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3089         debug!("(getting traits containing item) looking for '{}'", name);
3090
3091         let mut found_traits = Vec::new();
3092         // Look for the current trait.
3093         if let Some((trait_def_id, _)) = self.current_trait_ref {
3094             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3095                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3096             }
3097         }
3098
3099         let mut search_module = self.current_module;
3100         loop {
3101             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3102             match search_module.kind {
3103                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3104                 _ => break,
3105             }
3106         }
3107
3108         if let Some(prelude) = self.prelude {
3109             if !search_module.no_implicit_prelude {
3110                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3111             }
3112         }
3113
3114         found_traits
3115     }
3116
3117     fn get_traits_in_module_containing_item(&mut self,
3118                                             name: Name,
3119                                             ns: Namespace,
3120                                             module: Module,
3121                                             found_traits: &mut Vec<TraitCandidate>) {
3122         let mut traits = module.traits.borrow_mut();
3123         if traits.is_none() {
3124             let mut collected_traits = Vec::new();
3125             module.for_each_child(|name, ns, binding| {
3126                 if ns != TypeNS { return }
3127                 if let Def::Trait(_) = binding.def() {
3128                     collected_traits.push((name, binding));
3129                 }
3130             });
3131             *traits = Some(collected_traits.into_boxed_slice());
3132         }
3133
3134         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3135             let trait_def_id = binding.def().def_id();
3136             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3137                 let import_id = match binding.kind {
3138                     NameBindingKind::Import { directive, .. } => {
3139                         self.maybe_unused_trait_imports.insert(directive.id);
3140                         self.add_to_glob_map(directive.id, trait_name);
3141                         Some(directive.id)
3142                     }
3143                     _ => None,
3144                 };
3145                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3146             }
3147         }
3148     }
3149
3150     /// When name resolution fails, this method can be used to look up candidate
3151     /// entities with the expected name. It allows filtering them using the
3152     /// supplied predicate (which should be used to only accept the types of
3153     /// definitions expected e.g. traits). The lookup spans across all crates.
3154     ///
3155     /// NOTE: The method does not look into imports, but this is not a problem,
3156     /// since we report the definitions (thus, the de-aliased imports).
3157     fn lookup_import_candidates<FilterFn>(&mut self,
3158                                           lookup_name: Name,
3159                                           namespace: Namespace,
3160                                           filter_fn: FilterFn)
3161                                           -> Vec<ImportSuggestion>
3162         where FilterFn: Fn(Def) -> bool
3163     {
3164         let mut candidates = Vec::new();
3165         let mut worklist = Vec::new();
3166         let mut seen_modules = FxHashSet();
3167         worklist.push((self.graph_root, Vec::new(), false));
3168
3169         while let Some((in_module,
3170                         path_segments,
3171                         in_module_is_extern)) = worklist.pop() {
3172             self.populate_module_if_necessary(in_module);
3173
3174             in_module.for_each_child(|ident, ns, name_binding| {
3175
3176                 // avoid imports entirely
3177                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3178                 // avoid non-importable candidates as well
3179                 if !name_binding.is_importable() { return; }
3180
3181                 // collect results based on the filter function
3182                 if ident.name == lookup_name && ns == namespace {
3183                     if filter_fn(name_binding.def()) {
3184                         // create the path
3185                         let mut segms = path_segments.clone();
3186                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3187                         let path = Path {
3188                             span: name_binding.span,
3189                             segments: segms,
3190                         };
3191                         // the entity is accessible in the following cases:
3192                         // 1. if it's defined in the same crate, it's always
3193                         // accessible (since private entities can be made public)
3194                         // 2. if it's defined in another crate, it's accessible
3195                         // only if both the module is public and the entity is
3196                         // declared as public (due to pruning, we don't explore
3197                         // outside crate private modules => no need to check this)
3198                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3199                             candidates.push(ImportSuggestion { path: path });
3200                         }
3201                     }
3202                 }
3203
3204                 // collect submodules to explore
3205                 if let Some(module) = name_binding.module() {
3206                     // form the path
3207                     let mut path_segments = path_segments.clone();
3208                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3209
3210                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3211                         // add the module to the lookup
3212                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3213                         if seen_modules.insert(module.def_id().unwrap()) {
3214                             worklist.push((module, path_segments, is_extern));
3215                         }
3216                     }
3217                 }
3218             })
3219         }
3220
3221         candidates
3222     }
3223
3224     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3225         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3226         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3227             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3228         }
3229     }
3230
3231     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3232         match *vis {
3233             ast::Visibility::Public => ty::Visibility::Public,
3234             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3235             ast::Visibility::Inherited => {
3236                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3237             }
3238             ast::Visibility::Restricted { ref path, id } => {
3239                 let def = self.smart_resolve_path(id, None, path,
3240                                                   PathSource::Visibility).base_def();
3241                 if def == Def::Err {
3242                     ty::Visibility::Public
3243                 } else {
3244                     let vis = ty::Visibility::Restricted(def.def_id());
3245                     if self.is_accessible(vis) {
3246                         vis
3247                     } else {
3248                         self.session.span_err(path.span, "visibilities can only be restricted \
3249                                                           to ancestor modules");
3250                         ty::Visibility::Public
3251                     }
3252                 }
3253             }
3254         }
3255     }
3256
3257     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3258         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3259     }
3260
3261     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3262         vis.is_accessible_from(module.normal_ancestor_id, self)
3263     }
3264
3265     fn report_errors(&mut self) {
3266         self.report_shadowing_errors();
3267         let mut reported_spans = FxHashSet();
3268
3269         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3270             if !reported_spans.insert(span) { continue }
3271             let participle = |binding: &NameBinding| {
3272                 if binding.is_import() { "imported" } else { "defined" }
3273             };
3274             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3275             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3276             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3277                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3278             } else if let Def::Macro(..) = b1.def() {
3279                 format!("macro-expanded {} do not shadow",
3280                         if b1.is_import() { "macro imports" } else { "macros" })
3281             } else {
3282                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3283                         if b1.is_import() { "imports" } else { "items" })
3284             };
3285             if legacy {
3286                 let id = match b2.kind {
3287                     NameBindingKind::Import { directive, .. } => directive.id,
3288                     _ => unreachable!(),
3289                 };
3290                 let mut span = MultiSpan::from_span(span);
3291                 span.push_span_label(b1.span, msg1);
3292                 span.push_span_label(b2.span, msg2);
3293                 let msg = format!("`{}` is ambiguous", name);
3294                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3295             } else {
3296                 let mut err =
3297                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3298                 err.span_note(b1.span, &msg1);
3299                 match b2.def() {
3300                     Def::Macro(..) if b2.span == DUMMY_SP =>
3301                         err.note(&format!("`{}` is also a builtin macro", name)),
3302                     _ => err.span_note(b2.span, &msg2),
3303                 };
3304                 err.note(&note).emit();
3305             }
3306         }
3307
3308         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3309             if !reported_spans.insert(span) { continue }
3310             if binding.is_extern_crate() {
3311                 // Warn when using an inaccessible extern crate.
3312                 let node_id = match binding.kind {
3313                     NameBindingKind::Import { directive, .. } => directive.id,
3314                     _ => unreachable!(),
3315                 };
3316                 let msg = format!("extern crate `{}` is private", name);
3317                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3318             } else {
3319                 let def = binding.def();
3320                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3321             }
3322         }
3323     }
3324
3325     fn report_shadowing_errors(&mut self) {
3326         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3327             self.resolve_legacy_scope(scope, name, true);
3328         }
3329
3330         let mut reported_errors = FxHashSet();
3331         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3332             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3333                reported_errors.insert((binding.name, binding.span)) {
3334                 let msg = format!("`{}` is already in scope", binding.name);
3335                 self.session.struct_span_err(binding.span, &msg)
3336                     .note("macro-expanded `macro_rules!`s may not shadow \
3337                            existing macros (see RFC 1560)")
3338                     .emit();
3339             }
3340         }
3341     }
3342
3343     fn report_conflict(&mut self,
3344                        parent: Module,
3345                        ident: Ident,
3346                        ns: Namespace,
3347                        binding: &NameBinding,
3348                        old_binding: &NameBinding) {
3349         // Error on the second of two conflicting names
3350         if old_binding.span.lo > binding.span.lo {
3351             return self.report_conflict(parent, ident, ns, old_binding, binding);
3352         }
3353
3354         let container = match parent.kind {
3355             ModuleKind::Def(Def::Mod(_), _) => "module",
3356             ModuleKind::Def(Def::Trait(_), _) => "trait",
3357             ModuleKind::Block(..) => "block",
3358             _ => "enum",
3359         };
3360
3361         let (participle, noun) = match old_binding.is_import() {
3362             true => ("imported", "import"),
3363             false => ("defined", "definition"),
3364         };
3365
3366         let (name, span) = (ident.name, binding.span);
3367
3368         if let Some(s) = self.name_already_seen.get(&name) {
3369             if s == &span {
3370                 return;
3371             }
3372         }
3373
3374         let msg = {
3375             let kind = match (ns, old_binding.module()) {
3376                 (ValueNS, _) => "a value",
3377                 (MacroNS, _) => "a macro",
3378                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3379                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3380                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3381                 (TypeNS, _) => "a type",
3382             };
3383             format!("{} named `{}` has already been {} in this {}",
3384                     kind, name, participle, container)
3385         };
3386
3387         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3388             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3389             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3390                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3391                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3392             },
3393             _ => match (old_binding.is_import(), binding.is_import()) {
3394                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3395                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3396                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3397             },
3398         };
3399
3400         err.span_label(span, format!("`{}` already {}", name, participle));
3401         if old_binding.span != syntax_pos::DUMMY_SP {
3402             err.span_label(old_binding.span, format!("previous {} of `{}` here", noun, name));
3403         }
3404         err.emit();
3405         self.name_already_seen.insert(name, span);
3406     }
3407
3408     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3409         let (id, span) = (directive.id, directive.span);
3410         let msg = "`self` no longer imports values".to_string();
3411         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3412     }
3413
3414     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3415         if self.proc_macro_enabled { return; }
3416
3417         for attr in attrs {
3418             if attr.path.segments.len() > 1 {
3419                 continue
3420             }
3421             let ident = attr.path.segments[0].identifier;
3422             let result = self.resolve_lexical_macro_path_segment(ident,
3423                                                                  MacroNS,
3424                                                                  false,
3425                                                                  attr.path.span);
3426             if let Ok(binding) = result {
3427                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3428                     attr::mark_known(attr);
3429
3430                     let msg = "attribute procedural macros are experimental";
3431                     let feature = "proc_macro";
3432
3433                     feature_err(&self.session.parse_sess, feature,
3434                                 attr.span, GateIssue::Language, msg)
3435                         .span_note(binding.span(), "procedural macro imported here")
3436                         .emit();
3437                 }
3438             }
3439         }
3440     }
3441 }
3442
3443 fn is_struct_like(def: Def) -> bool {
3444     match def {
3445         Def::VariantCtor(_, CtorKind::Fictive) => true,
3446         _ => PathSource::Struct.is_expected(def),
3447     }
3448 }
3449
3450 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3451     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3452 }
3453
3454 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3455     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3456 }
3457
3458 fn names_to_string(idents: &[Ident]) -> String {
3459     let mut result = String::new();
3460     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3461         if i > 0 {
3462             result.push_str("::");
3463         }
3464         result.push_str(&ident.name.as_str());
3465     }
3466     result
3467 }
3468
3469 fn path_names_to_string(path: &Path) -> String {
3470     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3471 }
3472
3473 /// Get the path for an enum and the variant from an `ImportSuggestion` for an enum variant.
3474 fn import_candidate_to_paths(suggestion: &ImportSuggestion) -> (Span, String, String) {
3475     let variant_path = &suggestion.path;
3476     let variant_path_string = path_names_to_string(variant_path);
3477
3478     let path_len = suggestion.path.segments.len();
3479     let enum_path = ast::Path {
3480         span: suggestion.path.span,
3481         segments: suggestion.path.segments[0..path_len - 1].to_vec(),
3482     };
3483     let enum_path_string = path_names_to_string(&enum_path);
3484
3485     (suggestion.path.span, variant_path_string, enum_path_string)
3486 }
3487
3488
3489 /// When an entity with a given name is not available in scope, we search for
3490 /// entities with that name in all crates. This method allows outputting the
3491 /// results of this search in a programmer-friendly way
3492 fn show_candidates(err: &mut DiagnosticBuilder,
3493                    span: Span,
3494                    candidates: &[ImportSuggestion],
3495                    better: bool) {
3496
3497     // we want consistent results across executions, but candidates are produced
3498     // by iterating through a hash map, so make sure they are ordered:
3499     let mut path_strings: Vec<_> =
3500         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3501     path_strings.sort();
3502
3503     let better = if better { "better " } else { "" };
3504     let msg_diff = match path_strings.len() {
3505         1 => " is found in another module, you can import it",
3506         _ => "s are found in other modules, you can import them",
3507     };
3508     let msg = format!("possible {}candidate{} into scope", better, msg_diff);
3509
3510     for candidate in &mut path_strings {
3511         *candidate = format!("use {};\n", candidate);
3512     }
3513
3514     err.span_suggestions(span, &msg, path_strings);
3515 }
3516
3517 /// A somewhat inefficient routine to obtain the name of a module.
3518 fn module_to_string(module: Module) -> String {
3519     let mut names = Vec::new();
3520
3521     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3522         if let ModuleKind::Def(_, name) = module.kind {
3523             if let Some(parent) = module.parent {
3524                 names.push(Ident::with_empty_ctxt(name));
3525                 collect_mod(names, parent);
3526             }
3527         } else {
3528             // danger, shouldn't be ident?
3529             names.push(Ident::from_str("<opaque>"));
3530             collect_mod(names, module.parent.unwrap());
3531         }
3532     }
3533     collect_mod(&mut names, module);
3534
3535     if names.is_empty() {
3536         return "???".to_string();
3537     }
3538     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3539 }
3540
3541 fn err_path_resolution() -> PathResolution {
3542     PathResolution::new(Def::Err)
3543 }
3544
3545 #[derive(PartialEq,Copy, Clone)]
3546 pub enum MakeGlobMap {
3547     Yes,
3548     No,
3549 }
3550
3551 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }