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 #![crate_type = "dylib"]
  13 #![crate_type = "rlib"]
  14 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  15       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  16       html_root_url = "https://doc.rust-lang.org/nightly/")]
  17 #![deny(warnings)]
  18
  19 #![feature(associated_consts)]
  20 #![feature(rustc_diagnostic_macros)]
  21
  22 #![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
  23 #![cfg_attr(stage0, feature(rustc_private))]
  24 #![cfg_attr(stage0, feature(staged_api))]
  25
  26 #[macro_use]
  27 extern crate log;
  28 #[macro_use]
  29 extern crate syntax;
  30 extern crate syntax_pos;
  31 extern crate rustc_errors as errors;
  32 extern crate arena;
  33 #[macro_use]
  34 extern crate rustc;
  35
  36 use self::Namespace::*;
  37 use self::TypeParameters::*;
  38 use self::RibKind::*;
  39
  40 use rustc::hir::map::{Definitions, DefCollector};
  41 use rustc::hir::{self, PrimTy, TyBool, TyChar, TyFloat, TyInt, TyUint, TyStr};
  42 use rustc::middle::cstore::CrateLoader;
  43 use rustc::session::Session;
  44 use rustc::lint;
  45 use rustc::hir::def::*;
  46 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  47 use rustc::ty;
  48 use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
  49 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
  50
  51 use syntax::ext::hygiene::{Mark, SyntaxContext};
  52 use syntax::ast::{self, Name, NodeId, Ident, SpannedIdent, FloatTy, IntTy, UintTy};
  53 use syntax::ext::base::SyntaxExtension;
  54 use syntax::ext::base::Determinacy::{Determined, Undetermined};
  55 use syntax::ext::base::MacroKind;
  56 use syntax::symbol::{Symbol, keywords};
  57 use syntax::util::lev_distance::find_best_match_for_name;
  58
  59 use syntax::visit::{self, FnKind, Visitor};
  60 use syntax::attr;
  61 use syntax::ast::{Arm, BindingMode, Block, Crate, Expr, ExprKind};
  62 use syntax::ast::{FnDecl, ForeignItem, ForeignItemKind, Generics};
  63 use syntax::ast::{Item, ItemKind, ImplItem, ImplItemKind};
  64 use syntax::ast::{Local, Mutability, Pat, PatKind, Path};
  65 use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
  66 use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
  67
  68 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  69 use errors::DiagnosticBuilder;
  70
  71 use std::cell::{Cell, RefCell};
  72 use std::cmp;
  73 use std::collections::BTreeSet;
  74 use std::fmt;
  75 use std::mem::replace;
  76 use std::rc::Rc;
  77
  78 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
  79 use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
  80
  81 // NB: This module needs to be declared first so diagnostics are
  82 // registered before they are used.
  83 mod diagnostics;
  84
  85 mod macros;
  86 mod check_unused;
  87 mod build_reduced_graph;
  88 mod resolve_imports;
  89
  90 /// A free importable items suggested in case of resolution failure.
  91 struct ImportSuggestion {
  92     path: Path,
  93 }
  94
  95 /// A field or associated item from self type suggested in case of resolution failure.
  96 enum AssocSuggestion {
  97     Field,
  98     MethodWithSelf,
  99     AssocItem,
 100 }
 101
 102 #[derive(Eq)]
 103 struct BindingError {
 104     name: Name,
 105     origin: BTreeSet<Span>,
 106     target: BTreeSet<Span>,
 107 }
 108
 109 impl PartialOrd for BindingError {
 110     fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
 111         Some(self.cmp(other))
 112     }
 113 }
 114
 115 impl PartialEq for BindingError {
 116     fn eq(&self, other: &BindingError) -> bool {
 117         self.name == other.name
 118     }
 119 }
 120
 121 impl Ord for BindingError {
 122     fn cmp(&self, other: &BindingError) -> cmp::Ordering {
 123         self.name.cmp(&other.name)
 124     }
 125 }
 126
 127 enum ResolutionError<'a> {
 128     /// error E0401: can't use type parameters from outer function
 129     TypeParametersFromOuterFunction,
 130     /// error E0403: the name is already used for a type parameter in this type parameter list
 131     NameAlreadyUsedInTypeParameterList(Name, &'a Span),
 132     /// error E0407: method is not a member of trait
 133     MethodNotMemberOfTrait(Name, &'a str),
 134     /// error E0437: type is not a member of trait
 135     TypeNotMemberOfTrait(Name, &'a str),
 136     /// error E0438: const is not a member of trait
 137     ConstNotMemberOfTrait(Name, &'a str),
 138     /// error E0408: variable `{}` is not bound in all patterns
 139     VariableNotBoundInPattern(&'a BindingError),
 140     /// error E0409: variable `{}` is bound in inconsistent ways within the same match arm
 141     VariableBoundWithDifferentMode(Name, Span),
 142     /// error E0415: identifier is bound more than once in this parameter list
 143     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 144     /// error E0416: identifier is bound more than once in the same pattern
 145     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 146     /// error E0426: use of undeclared label
 147     UndeclaredLabel(&'a str),
 148     /// error E0429: `self` imports are only allowed within a { } list
 149     SelfImportsOnlyAllowedWithin,
 150     /// error E0430: `self` import can only appear once in the list
 151     SelfImportCanOnlyAppearOnceInTheList,
 152     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 153     SelfImportOnlyInImportListWithNonEmptyPrefix,
 154     /// error E0432: unresolved import
 155     UnresolvedImport(Option<(&'a str, &'a str)>),
 156     /// error E0433: failed to resolve
 157     FailedToResolve(&'a str),
 158     /// error E0434: can't capture dynamic environment in a fn item
 159     CannotCaptureDynamicEnvironmentInFnItem,
 160     /// error E0435: attempt to use a non-constant value in a constant
 161     AttemptToUseNonConstantValueInConstant,
 162     /// error E0530: X bindings cannot shadow Ys
 163     BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
 164     /// error E0128: type parameters with a default cannot use forward declared identifiers
 165     ForwardDeclaredTyParam,
 166 }
 167
 168 fn resolve_error<'sess, 'a>(resolver: &'sess Resolver,
 169                             span: Span,
 170                             resolution_error: ResolutionError<'a>) {
 171     resolve_struct_error(resolver, span, resolution_error).emit();
 172 }
 173
 174 fn resolve_struct_error<'sess, 'a>(resolver: &'sess Resolver,
 175                                    span: Span,
 176                                    resolution_error: ResolutionError<'a>)
 177                                    -> DiagnosticBuilder<'sess> {
 178     match resolution_error {
 179         ResolutionError::TypeParametersFromOuterFunction => {
 180             let mut err = struct_span_err!(resolver.session,
 181                                            span,
 182                                            E0401,
 183                                            "can't use type parameters from outer function; \
 184                                            try using a local type parameter instead");
 185             err.span_label(span, "use of type variable from outer function");
 186             err
 187         }
 188         ResolutionError::NameAlreadyUsedInTypeParameterList(name, first_use_span) => {
 189              let mut err = struct_span_err!(resolver.session,
 190                                             span,
 191                                             E0403,
 192                                             "the name `{}` is already used for a type parameter \
 193                                             in this type parameter list",
 194                                             name);
 195              err.span_label(span, "already used");
 196              err.span_label(first_use_span.clone(), format!("first use of `{}`", name));
 197              err
 198         }
 199         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 200             let mut err = struct_span_err!(resolver.session,
 201                                            span,
 202                                            E0407,
 203                                            "method `{}` is not a member of trait `{}`",
 204                                            method,
 205                                            trait_);
 206             err.span_label(span, format!("not a member of trait `{}`", trait_));
 207             err
 208         }
 209         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 210             let mut err = struct_span_err!(resolver.session,
 211                              span,
 212                              E0437,
 213                              "type `{}` is not a member of trait `{}`",
 214                              type_,
 215                              trait_);
 216             err.span_label(span, format!("not a member of trait `{}`", trait_));
 217             err
 218         }
 219         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 220             let mut err = struct_span_err!(resolver.session,
 221                              span,
 222                              E0438,
 223                              "const `{}` is not a member of trait `{}`",
 224                              const_,
 225                              trait_);
 226             err.span_label(span, format!("not a member of trait `{}`", trait_));
 227             err
 228         }
 229         ResolutionError::VariableNotBoundInPattern(binding_error) => {
 230             let target_sp = binding_error.target.iter().map(|x| *x).collect::<Vec<_>>();
 231             let msp = MultiSpan::from_spans(target_sp.clone());
 232             let msg = format!("variable `{}` is not bound in all patterns", binding_error.name);
 233             let mut err = resolver.session.struct_span_err_with_code(msp, &msg, "E0408");
 234             for sp in target_sp {
 235                 err.span_label(sp, format!("pattern doesn't bind `{}`", binding_error.name));
 236             }
 237             let origin_sp = binding_error.origin.iter().map(|x| *x).collect::<Vec<_>>();
 238             for sp in origin_sp {
 239                 err.span_label(sp, "variable not in all patterns");
 240             }
 241             err
 242         }
 243         ResolutionError::VariableBoundWithDifferentMode(variable_name,
 244                                                         first_binding_span) => {
 245             let mut err = struct_span_err!(resolver.session,
 246                              span,
 247                              E0409,
 248                              "variable `{}` is bound in inconsistent \
 249                              ways within the same match arm",
 250                              variable_name);
 251             err.span_label(span, "bound in different ways");
 252             err.span_label(first_binding_span, "first binding");
 253             err
 254         }
 255         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 256             let mut err = struct_span_err!(resolver.session,
 257                              span,
 258                              E0415,
 259                              "identifier `{}` is bound more than once in this parameter list",
 260                              identifier);
 261             err.span_label(span, "used as parameter more than once");
 262             err
 263         }
 264         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 265             let mut err = struct_span_err!(resolver.session,
 266                              span,
 267                              E0416,
 268                              "identifier `{}` is bound more than once in the same pattern",
 269                              identifier);
 270             err.span_label(span, "used in a pattern more than once");
 271             err
 272         }
 273         ResolutionError::UndeclaredLabel(name) => {
 274             let mut err = struct_span_err!(resolver.session,
 275                                            span,
 276                                            E0426,
 277                                            "use of undeclared label `{}`",
 278                                            name);
 279             err.span_label(span, format!("undeclared label `{}`", name));
 280             err
 281         }
 282         ResolutionError::SelfImportsOnlyAllowedWithin => {
 283             struct_span_err!(resolver.session,
 284                              span,
 285                              E0429,
 286                              "{}",
 287                              "`self` imports are only allowed within a { } list")
 288         }
 289         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 290             struct_span_err!(resolver.session,
 291                              span,
 292                              E0430,
 293                              "`self` import can only appear once in the list")
 294         }
 295         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 296             struct_span_err!(resolver.session,
 297                              span,
 298                              E0431,
 299                              "`self` import can only appear in an import list with a \
 300                               non-empty prefix")
 301         }
 302         ResolutionError::UnresolvedImport(name) => {
 303             let msg = match name {
 304                 Some((n, _)) => format!("unresolved import `{}`", n),
 305                 None => "unresolved import".to_owned(),
 306             };
 307             let mut err = struct_span_err!(resolver.session, span, E0432, "{}", msg);
 308             if let Some((_, p)) = name {
 309                 err.span_label(span, p);
 310             }
 311             err
 312         }
 313         ResolutionError::FailedToResolve(msg) => {
 314             let mut err = struct_span_err!(resolver.session, span, E0433,
 315                                            "failed to resolve. {}", msg);
 316             err.span_label(span, msg);
 317             err
 318         }
 319         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 320             struct_span_err!(resolver.session,
 321                              span,
 322                              E0434,
 323                              "{}",
 324                              "can't capture dynamic environment in a fn item; use the || { ... } \
 325                               closure form instead")
 326         }
 327         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 328             let mut err = struct_span_err!(resolver.session,
 329                              span,
 330                              E0435,
 331                              "attempt to use a non-constant value in a constant");
 332             err.span_label(span, "non-constant used with constant");
 333             err
 334         }
 335         ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
 336             let shadows_what = PathResolution::new(binding.def()).kind_name();
 337             let mut err = struct_span_err!(resolver.session,
 338                                            span,
 339                                            E0530,
 340                                            "{}s cannot shadow {}s", what_binding, shadows_what);
 341             err.span_label(span, format!("cannot be named the same as a {}", shadows_what));
 342             let participle = if binding.is_import() { "imported" } else { "defined" };
 343             let msg = format!("a {} `{}` is {} here", shadows_what, name, participle);
 344             err.span_label(binding.span, msg);
 345             err
 346         }
 347         ResolutionError::ForwardDeclaredTyParam => {
 348             let mut err = struct_span_err!(resolver.session, span, E0128,
 349                                            "type parameters with a default cannot use \
 350                                             forward declared identifiers");
 351             err.span_label(span, format!("defaulted type parameters \
 352                                            cannot be forward declared"));
 353             err
 354         }
 355     }
 356 }
 357
 358 #[derive(Copy, Clone, Debug)]
 359 struct BindingInfo {
 360     span: Span,
 361     binding_mode: BindingMode,
 362 }
 363
 364 // Map from the name in a pattern to its binding mode.
 365 type BindingMap = FxHashMap<Ident, BindingInfo>;
 366
 367 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 368 enum PatternSource {
 369     Match,
 370     IfLet,
 371     WhileLet,
 372     Let,
 373     For,
 374     FnParam,
 375 }
 376
 377 impl PatternSource {
 378     fn is_refutable(self) -> bool {
 379         match self {
 380             PatternSource::Match | PatternSource::IfLet | PatternSource::WhileLet => true,
 381             PatternSource::Let | PatternSource::For | PatternSource::FnParam  => false,
 382         }
 383     }
 384     fn descr(self) -> &'static str {
 385         match self {
 386             PatternSource::Match => "match binding",
 387             PatternSource::IfLet => "if let binding",
 388             PatternSource::WhileLet => "while let binding",
 389             PatternSource::Let => "let binding",
 390             PatternSource::For => "for binding",
 391             PatternSource::FnParam => "function parameter",
 392         }
 393     }
 394 }
 395
 396 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 397 enum PathSource<'a> {
 398     // Type paths `Path`.
 399     Type,
 400     // Trait paths in bounds or impls.
 401     Trait,
 402     // Expression paths `path`, with optional parent context.
 403     Expr(Option<&'a Expr>),
 404     // Paths in path patterns `Path`.
 405     Pat,
 406     // Paths in struct expressions and patterns `Path { .. }`.
 407     Struct,
 408     // Paths in tuple struct patterns `Path(..)`.
 409     TupleStruct,
 410     // `m::A::B` in `<T as m::A>::B::C`.
 411     TraitItem(Namespace),
 412     // Path in `pub(path)`
 413     Visibility,
 414     // Path in `use a::b::{...};`
 415     ImportPrefix,
 416 }
 417
 418 impl<'a> PathSource<'a> {
 419     fn namespace(self) -> Namespace {
 420         match self {
 421             PathSource::Type | PathSource::Trait | PathSource::Struct |
 422             PathSource::Visibility | PathSource::ImportPrefix => TypeNS,
 423             PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
 424             PathSource::TraitItem(ns) => ns,
 425         }
 426     }
 427
 428     fn global_by_default(self) -> bool {
 429         match self {
 430             PathSource::Visibility | PathSource::ImportPrefix => true,
 431             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 432             PathSource::Struct | PathSource::TupleStruct |
 433             PathSource::Trait | PathSource::TraitItem(..) => false,
 434         }
 435     }
 436
 437     fn defer_to_typeck(self) -> bool {
 438         match self {
 439             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 440             PathSource::Struct | PathSource::TupleStruct => true,
 441             PathSource::Trait | PathSource::TraitItem(..) |
 442             PathSource::Visibility | PathSource::ImportPrefix => false,
 443         }
 444     }
 445
 446     fn descr_expected(self) -> &'static str {
 447         match self {
 448             PathSource::Type => "type",
 449             PathSource::Trait => "trait",
 450             PathSource::Pat => "unit struct/variant or constant",
 451             PathSource::Struct => "struct, variant or union type",
 452             PathSource::TupleStruct => "tuple struct/variant",
 453             PathSource::Visibility => "module",
 454             PathSource::ImportPrefix => "module or enum",
 455             PathSource::TraitItem(ns) => match ns {
 456                 TypeNS => "associated type",
 457                 ValueNS => "method or associated constant",
 458                 MacroNS => bug!("associated macro"),
 459             },
 460             PathSource::Expr(parent) => match parent.map(|p| &p.node) {
 461                 // "function" here means "anything callable" rather than `Def::Fn`,
 462                 // this is not precise but usually more helpful than just "value".
 463                 Some(&ExprKind::Call(..)) => "function",
 464                 _ => "value",
 465             },
 466         }
 467     }
 468
 469     fn is_expected(self, def: Def) -> bool {
 470         match self {
 471             PathSource::Type => match def {
 472                 Def::Struct(..) | Def::Union(..) | Def::Enum(..) |
 473                 Def::Trait(..) | Def::TyAlias(..) | Def::AssociatedTy(..) |
 474                 Def::PrimTy(..) | Def::TyParam(..) | Def::SelfTy(..) => true,
 475                 _ => false,
 476             },
 477             PathSource::Trait => match def {
 478                 Def::Trait(..) => true,
 479                 _ => false,
 480             },
 481             PathSource::Expr(..) => match def {
 482                 Def::StructCtor(_, CtorKind::Const) | Def::StructCtor(_, CtorKind::Fn) |
 483                 Def::VariantCtor(_, CtorKind::Const) | Def::VariantCtor(_, CtorKind::Fn) |
 484                 Def::Const(..) | Def::Static(..) | Def::Local(..) | Def::Upvar(..) |
 485                 Def::Fn(..) | Def::Method(..) | Def::AssociatedConst(..) => true,
 486                 _ => false,
 487             },
 488             PathSource::Pat => match def {
 489                 Def::StructCtor(_, CtorKind::Const) |
 490                 Def::VariantCtor(_, CtorKind::Const) |
 491                 Def::Const(..) | Def::AssociatedConst(..) => true,
 492                 _ => false,
 493             },
 494             PathSource::TupleStruct => match def {
 495                 Def::StructCtor(_, CtorKind::Fn) | Def::VariantCtor(_, CtorKind::Fn) => true,
 496                 _ => false,
 497             },
 498             PathSource::Struct => match def {
 499                 Def::Struct(..) | Def::Union(..) | Def::Variant(..) |
 500                 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => true,
 501                 _ => false,
 502             },
 503             PathSource::TraitItem(ns) => match def {
 504                 Def::AssociatedConst(..) | Def::Method(..) if ns == ValueNS => true,
 505                 Def::AssociatedTy(..) if ns == TypeNS => true,
 506                 _ => false,
 507             },
 508             PathSource::ImportPrefix => match def {
 509                 Def::Mod(..) | Def::Enum(..) => true,
 510                 _ => false,
 511             },
 512             PathSource::Visibility => match def {
 513                 Def::Mod(..) => true,
 514                 _ => false,
 515             },
 516         }
 517     }
 518
 519     fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
 520         __diagnostic_used!(E0404);
 521         __diagnostic_used!(E0405);
 522         __diagnostic_used!(E0412);
 523         __diagnostic_used!(E0422);
 524         __diagnostic_used!(E0423);
 525         __diagnostic_used!(E0425);
 526         __diagnostic_used!(E0531);
 527         __diagnostic_used!(E0532);
 528         __diagnostic_used!(E0573);
 529         __diagnostic_used!(E0574);
 530         __diagnostic_used!(E0575);
 531         __diagnostic_used!(E0576);
 532         __diagnostic_used!(E0577);
 533         __diagnostic_used!(E0578);
 534         match (self, has_unexpected_resolution) {
 535             (PathSource::Trait, true) => "E0404",
 536             (PathSource::Trait, false) => "E0405",
 537             (PathSource::Type, true) => "E0573",
 538             (PathSource::Type, false) => "E0412",
 539             (PathSource::Struct, true) => "E0574",
 540             (PathSource::Struct, false) => "E0422",
 541             (PathSource::Expr(..), true) => "E0423",
 542             (PathSource::Expr(..), false) => "E0425",
 543             (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
 544             (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
 545             (PathSource::TraitItem(..), true) => "E0575",
 546             (PathSource::TraitItem(..), false) => "E0576",
 547             (PathSource::Visibility, true) | (PathSource::ImportPrefix, true) => "E0577",
 548             (PathSource::Visibility, false) | (PathSource::ImportPrefix, false) => "E0578",
 549         }
 550     }
 551 }
 552
 553 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 554 pub enum Namespace {
 555     TypeNS,
 556     ValueNS,
 557     MacroNS,
 558 }
 559
 560 #[derive(Clone, Default, Debug)]
 561 pub struct PerNS<T> {
 562     value_ns: T,
 563     type_ns: T,
 564     macro_ns: Option<T>,
 565 }
 566
 567 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
 568     type Output = T;
 569     fn index(&self, ns: Namespace) -> &T {
 570         match ns {
 571             ValueNS => &self.value_ns,
 572             TypeNS => &self.type_ns,
 573             MacroNS => self.macro_ns.as_ref().unwrap(),
 574         }
 575     }
 576 }
 577
 578 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
 579     fn index_mut(&mut self, ns: Namespace) -> &mut T {
 580         match ns {
 581             ValueNS => &mut self.value_ns,
 582             TypeNS => &mut self.type_ns,
 583             MacroNS => self.macro_ns.as_mut().unwrap(),
 584         }
 585     }
 586 }
 587
 588 impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
 589     fn visit_item(&mut self, item: &'tcx Item) {
 590         self.resolve_item(item);
 591     }
 592     fn visit_arm(&mut self, arm: &'tcx Arm) {
 593         self.resolve_arm(arm);
 594     }
 595     fn visit_block(&mut self, block: &'tcx Block) {
 596         self.resolve_block(block);
 597     }
 598     fn visit_expr(&mut self, expr: &'tcx Expr) {
 599         self.resolve_expr(expr, None);
 600     }
 601     fn visit_local(&mut self, local: &'tcx Local) {
 602         self.resolve_local(local);
 603     }
 604     fn visit_ty(&mut self, ty: &'tcx Ty) {
 605         if let TyKind::Path(ref qself, ref path) = ty.node {
 606             self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
 607         } else if let TyKind::ImplicitSelf = ty.node {
 608             let self_ty = keywords::SelfType.ident();
 609             let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, true, ty.span)
 610                           .map_or(Def::Err, |d| d.def());
 611             self.record_def(ty.id, PathResolution::new(def));
 612         } else if let TyKind::Array(ref element, ref length) = ty.node {
 613             self.visit_ty(element);
 614             self.with_constant_rib(|this| {
 615                 this.visit_expr(length);
 616             });
 617             return;
 618         }
 619         visit::walk_ty(self, ty);
 620     }
 621     fn visit_poly_trait_ref(&mut self,
 622                             tref: &'tcx ast::PolyTraitRef,
 623                             m: &'tcx ast::TraitBoundModifier) {
 624         self.smart_resolve_path(tref.trait_ref.ref_id, None,
 625                                 &tref.trait_ref.path, PathSource::Trait);
 626         visit::walk_poly_trait_ref(self, tref, m);
 627     }
 628     fn visit_variant(&mut self,
 629                      variant: &'tcx ast::Variant,
 630                      generics: &'tcx Generics,
 631                      item_id: ast::NodeId) {
 632         if let Some(ref dis_expr) = variant.node.disr_expr {
 633             // resolve the discriminator expr as a constant
 634             self.with_constant_rib(|this| {
 635                 this.visit_expr(dis_expr);
 636             });
 637         }
 638
 639         // `visit::walk_variant` without the discriminant expression.
 640         self.visit_variant_data(&variant.node.data,
 641                                 variant.node.name,
 642                                 generics,
 643                                 item_id,
 644                                 variant.span);
 645     }
 646     fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
 647         let type_parameters = match foreign_item.node {
 648             ForeignItemKind::Fn(_, ref generics) => {
 649                 HasTypeParameters(generics, ItemRibKind)
 650             }
 651             ForeignItemKind::Static(..) => NoTypeParameters,
 652         };
 653         self.with_type_parameter_rib(type_parameters, |this| {
 654             visit::walk_foreign_item(this, foreign_item);
 655         });
 656     }
 657     fn visit_fn(&mut self,
 658                 function_kind: FnKind<'tcx>,
 659                 declaration: &'tcx FnDecl,
 660                 _: Span,
 661                 node_id: NodeId) {
 662         let rib_kind = match function_kind {
 663             FnKind::ItemFn(_, generics, ..) => {
 664                 self.visit_generics(generics);
 665                 ItemRibKind
 666             }
 667             FnKind::Method(_, sig, _, _) => {
 668                 self.visit_generics(&sig.generics);
 669                 MethodRibKind(!sig.decl.has_self())
 670             }
 671             FnKind::Closure(_) => ClosureRibKind(node_id),
 672         };
 673
 674         // Create a value rib for the function.
 675         self.ribs[ValueNS].push(Rib::new(rib_kind));
 676
 677         // Create a label rib for the function.
 678         self.label_ribs.push(Rib::new(rib_kind));
 679
 680         // Add each argument to the rib.
 681         let mut bindings_list = FxHashMap();
 682         for argument in &declaration.inputs {
 683             self.resolve_pattern(&argument.pat, PatternSource::FnParam, &mut bindings_list);
 684
 685             self.visit_ty(&argument.ty);
 686
 687             debug!("(resolving function) recorded argument");
 688         }
 689         visit::walk_fn_ret_ty(self, &declaration.output);
 690
 691         // Resolve the function body.
 692         match function_kind {
 693             FnKind::ItemFn(.., body) |
 694             FnKind::Method(.., body) => {
 695                 self.visit_block(body);
 696             }
 697             FnKind::Closure(body) => {
 698                 self.visit_expr(body);
 699             }
 700         };
 701
 702         debug!("(resolving function) leaving function");
 703
 704         self.label_ribs.pop();
 705         self.ribs[ValueNS].pop();
 706     }
 707     fn visit_generics(&mut self, generics: &'tcx Generics) {
 708         // For type parameter defaults, we have to ban access
 709         // to following type parameters, as the Substs can only
 710         // provide previous type parameters as they're built.
 711         let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
 712         default_ban_rib.bindings.extend(generics.ty_params.iter()
 713             .skip_while(|p| p.default.is_none())
 714             .map(|p| (Ident::with_empty_ctxt(p.ident.name), Def::Err)));
 715
 716         for param in &generics.ty_params {
 717             for bound in &param.bounds {
 718                 self.visit_ty_param_bound(bound);
 719             }
 720
 721             if let Some(ref ty) = param.default {
 722                 self.ribs[TypeNS].push(default_ban_rib);
 723                 self.visit_ty(ty);
 724                 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
 725             }
 726
 727             // Allow all following defaults to refer to this type parameter.
 728             default_ban_rib.bindings.remove(&Ident::with_empty_ctxt(param.ident.name));
 729         }
 730         for lt in &generics.lifetimes { self.visit_lifetime_def(lt); }
 731         for p in &generics.where_clause.predicates { self.visit_where_predicate(p); }
 732     }
 733 }
 734
 735 pub type ErrorMessage = Option<(Span, String)>;
 736
 737 #[derive(Copy, Clone)]
 738 enum TypeParameters<'a, 'b> {
 739     NoTypeParameters,
 740     HasTypeParameters(// Type parameters.
 741                       &'b Generics,
 742
 743                       // The kind of the rib used for type parameters.
 744                       RibKind<'a>),
 745 }
 746
 747 // The rib kind controls the translation of local
 748 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 749 #[derive(Copy, Clone, Debug)]
 750 enum RibKind<'a> {
 751     // No translation needs to be applied.
 752     NormalRibKind,
 753
 754     // We passed through a closure scope at the given node ID.
 755     // Translate upvars as appropriate.
 756     ClosureRibKind(NodeId /* func id */),
 757
 758     // We passed through an impl or trait and are now in one of its
 759     // methods. Allow references to ty params that impl or trait
 760     // binds. Disallow any other upvars (including other ty params that are
 761     // upvars).
 762     //
 763     // The boolean value represents the fact that this method is static or not.
 764     MethodRibKind(bool),
 765
 766     // We passed through an item scope. Disallow upvars.
 767     ItemRibKind,
 768
 769     // We're in a constant item. Can't refer to dynamic stuff.
 770     ConstantItemRibKind,
 771
 772     // We passed through a module.
 773     ModuleRibKind(Module<'a>),
 774
 775     // We passed through a `macro_rules!` statement
 776     MacroDefinition(DefId),
 777
 778     // All bindings in this rib are type parameters that can't be used
 779     // from the default of a type parameter because they're not declared
 780     // before said type parameter. Also see the `visit_generics` override.
 781     ForwardTyParamBanRibKind,
 782 }
 783
 784 /// One local scope.
 785 #[derive(Debug)]
 786 struct Rib<'a> {
 787     bindings: FxHashMap<Ident, Def>,
 788     kind: RibKind<'a>,
 789 }
 790
 791 impl<'a> Rib<'a> {
 792     fn new(kind: RibKind<'a>) -> Rib<'a> {
 793         Rib {
 794             bindings: FxHashMap(),
 795             kind: kind,
 796         }
 797     }
 798 }
 799
 800 enum LexicalScopeBinding<'a> {
 801     Item(&'a NameBinding<'a>),
 802     Def(Def),
 803 }
 804
 805 impl<'a> LexicalScopeBinding<'a> {
 806     fn item(self) -> Option<&'a NameBinding<'a>> {
 807         match self {
 808             LexicalScopeBinding::Item(binding) => Some(binding),
 809             _ => None,
 810         }
 811     }
 812
 813     fn def(self) -> Def {
 814         match self {
 815             LexicalScopeBinding::Item(binding) => binding.def(),
 816             LexicalScopeBinding::Def(def) => def,
 817         }
 818     }
 819 }
 820
 821 #[derive(Clone)]
 822 enum PathResult<'a> {
 823     Module(Module<'a>),
 824     NonModule(PathResolution),
 825     Indeterminate,
 826     Failed(String, bool /* is the error from the last segment? */),
 827 }
 828
 829 enum ModuleKind {
 830     Block(NodeId),
 831     Def(Def, Name),
 832 }
 833
 834 /// One node in the tree of modules.
 835 pub struct ModuleData<'a> {
 836     parent: Option<Module<'a>>,
 837     kind: ModuleKind,
 838
 839     // The def id of the closest normal module (`mod`) ancestor (including this module).
 840     normal_ancestor_id: DefId,
 841
 842     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
 843     legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, Span, MacroKind)>>,
 844     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 845
 846     // Macro invocations that can expand into items in this module.
 847     unresolved_invocations: RefCell<FxHashSet<Mark>>,
 848
 849     no_implicit_prelude: bool,
 850
 851     glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
 852     globs: RefCell<Vec<&'a ImportDirective<'a>>>,
 853
 854     // Used to memoize the traits in this module for faster searches through all traits in scope.
 855     traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
 856
 857     // Whether this module is populated. If not populated, any attempt to
 858     // access the children must be preceded with a
 859     // `populate_module_if_necessary` call.
 860     populated: Cell<bool>,
 861
 862     /// Span of the module itself. Used for error reporting.
 863     span: Span,
 864 }
 865
 866 pub type Module<'a> = &'a ModuleData<'a>;
 867
 868 impl<'a> ModuleData<'a> {
 869     fn new(parent: Option<Module<'a>>,
 870            kind: ModuleKind,
 871            normal_ancestor_id: DefId,
 872            span: Span) -> Self {
 873         ModuleData {
 874             parent: parent,
 875             kind: kind,
 876             normal_ancestor_id: normal_ancestor_id,
 877             resolutions: RefCell::new(FxHashMap()),
 878             legacy_macro_resolutions: RefCell::new(Vec::new()),
 879             macro_resolutions: RefCell::new(Vec::new()),
 880             unresolved_invocations: RefCell::new(FxHashSet()),
 881             no_implicit_prelude: false,
 882             glob_importers: RefCell::new(Vec::new()),
 883             globs: RefCell::new((Vec::new())),
 884             traits: RefCell::new(None),
 885             populated: Cell::new(normal_ancestor_id.is_local()),
 886             span: span,
 887         }
 888     }
 889
 890     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 891         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 892             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 893         }
 894     }
 895
 896     fn def(&self) -> Option<Def> {
 897         match self.kind {
 898             ModuleKind::Def(def, _) => Some(def),
 899             _ => None,
 900         }
 901     }
 902
 903     fn def_id(&self) -> Option<DefId> {
 904         self.def().as_ref().map(Def::def_id)
 905     }
 906
 907     // `self` resolves to the first module ancestor that `is_normal`.
 908     fn is_normal(&self) -> bool {
 909         match self.kind {
 910             ModuleKind::Def(Def::Mod(_), _) => true,
 911             _ => false,
 912         }
 913     }
 914
 915     fn is_trait(&self) -> bool {
 916         match self.kind {
 917             ModuleKind::Def(Def::Trait(_), _) => true,
 918             _ => false,
 919         }
 920     }
 921
 922     fn is_local(&self) -> bool {
 923         self.normal_ancestor_id.is_local()
 924     }
 925
 926     fn nearest_item_scope(&'a self) -> Module<'a> {
 927         if self.is_trait() { self.parent.unwrap() } else { self }
 928     }
 929 }
 930
 931 impl<'a> fmt::Debug for ModuleData<'a> {
 932     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 933         write!(f, "{:?}", self.def())
 934     }
 935 }
 936
 937 // Records a possibly-private value, type, or module definition.
 938 #[derive(Clone, Debug)]
 939 pub struct NameBinding<'a> {
 940     kind: NameBindingKind<'a>,
 941     expansion: Mark,
 942     span: Span,
 943     vis: ty::Visibility,
 944 }
 945
 946 pub trait ToNameBinding<'a> {
 947     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 948 }
 949
 950 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 951     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 952         self
 953     }
 954 }
 955
 956 #[derive(Clone, Debug)]
 957 enum NameBindingKind<'a> {
 958     Def(Def),
 959     Module(Module<'a>),
 960     Import {
 961         binding: &'a NameBinding<'a>,
 962         directive: &'a ImportDirective<'a>,
 963         used: Cell<bool>,
 964         legacy_self_import: bool,
 965     },
 966     Ambiguity {
 967         b1: &'a NameBinding<'a>,
 968         b2: &'a NameBinding<'a>,
 969         legacy: bool,
 970     }
 971 }
 972
 973 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 974
 975 struct AmbiguityError<'a> {
 976     span: Span,
 977     name: Name,
 978     lexical: bool,
 979     b1: &'a NameBinding<'a>,
 980     b2: &'a NameBinding<'a>,
 981     legacy: bool,
 982 }
 983
 984 impl<'a> NameBinding<'a> {
 985     fn module(&self) -> Option<Module<'a>> {
 986         match self.kind {
 987             NameBindingKind::Module(module) => Some(module),
 988             NameBindingKind::Import { binding, .. } => binding.module(),
 989             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 990             _ => None,
 991         }
 992     }
 993
 994     fn def(&self) -> Def {
 995         match self.kind {
 996             NameBindingKind::Def(def) => def,
 997             NameBindingKind::Module(module) => module.def().unwrap(),
 998             NameBindingKind::Import { binding, .. } => binding.def(),
 999             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1000             NameBindingKind::Ambiguity { .. } => Def::Err,
1001         }
1002     }
1003
1004     fn def_ignoring_ambiguity(&self) -> Def {
1005         match self.kind {
1006             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1007             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1008             _ => self.def(),
1009         }
1010     }
1011
1012     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1013         resolver.get_macro(self.def_ignoring_ambiguity())
1014     }
1015
1016     // We sometimes need to treat variants as `pub` for backwards compatibility
1017     fn pseudo_vis(&self) -> ty::Visibility {
1018         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1019     }
1020
1021     fn is_variant(&self) -> bool {
1022         match self.kind {
1023             NameBindingKind::Def(Def::Variant(..)) |
1024             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1025             _ => false,
1026         }
1027     }
1028
1029     fn is_extern_crate(&self) -> bool {
1030         match self.kind {
1031             NameBindingKind::Import {
1032                 directive: &ImportDirective {
1033                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1034                 }, ..
1035             } => true,
1036             _ => false,
1037         }
1038     }
1039
1040     fn is_import(&self) -> bool {
1041         match self.kind {
1042             NameBindingKind::Import { .. } => true,
1043             _ => false,
1044         }
1045     }
1046
1047     fn is_glob_import(&self) -> bool {
1048         match self.kind {
1049             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1050             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1051             _ => false,
1052         }
1053     }
1054
1055     fn is_importable(&self) -> bool {
1056         match self.def() {
1057             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1058             _ => true,
1059         }
1060     }
1061 }
1062
1063 /// Interns the names of the primitive types.
1064 struct PrimitiveTypeTable {
1065     primitive_types: FxHashMap<Name, PrimTy>,
1066 }
1067
1068 impl PrimitiveTypeTable {
1069     fn new() -> PrimitiveTypeTable {
1070         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1071
1072         table.intern("bool", TyBool);
1073         table.intern("char", TyChar);
1074         table.intern("f32", TyFloat(FloatTy::F32));
1075         table.intern("f64", TyFloat(FloatTy::F64));
1076         table.intern("isize", TyInt(IntTy::Is));
1077         table.intern("i8", TyInt(IntTy::I8));
1078         table.intern("i16", TyInt(IntTy::I16));
1079         table.intern("i32", TyInt(IntTy::I32));
1080         table.intern("i64", TyInt(IntTy::I64));
1081         table.intern("i128", TyInt(IntTy::I128));
1082         table.intern("str", TyStr);
1083         table.intern("usize", TyUint(UintTy::Us));
1084         table.intern("u8", TyUint(UintTy::U8));
1085         table.intern("u16", TyUint(UintTy::U16));
1086         table.intern("u32", TyUint(UintTy::U32));
1087         table.intern("u64", TyUint(UintTy::U64));
1088         table.intern("u128", TyUint(UintTy::U128));
1089         table
1090     }
1091
1092     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1093         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1094     }
1095 }
1096
1097 /// The main resolver class.
1098 pub struct Resolver<'a> {
1099     session: &'a Session,
1100
1101     pub definitions: Definitions,
1102
1103     graph_root: Module<'a>,
1104
1105     prelude: Option<Module<'a>>,
1106
1107     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1108
1109     // Names of fields of an item `DefId` accessible with dot syntax.
1110     // Used for hints during error reporting.
1111     field_names: FxHashMap<DefId, Vec<Name>>,
1112
1113     // All imports known to succeed or fail.
1114     determined_imports: Vec<&'a ImportDirective<'a>>,
1115
1116     // All non-determined imports.
1117     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1118
1119     // The module that represents the current item scope.
1120     current_module: Module<'a>,
1121
1122     // The current set of local scopes for types and values.
1123     // FIXME #4948: Reuse ribs to avoid allocation.
1124     ribs: PerNS<Vec<Rib<'a>>>,
1125
1126     // The current set of local scopes, for labels.
1127     label_ribs: Vec<Rib<'a>>,
1128
1129     // The trait that the current context can refer to.
1130     current_trait_ref: Option<(DefId, TraitRef)>,
1131
1132     // The current self type if inside an impl (used for better errors).
1133     current_self_type: Option<Ty>,
1134
1135     // The idents for the primitive types.
1136     primitive_type_table: PrimitiveTypeTable,
1137
1138     def_map: DefMap,
1139     pub freevars: FreevarMap,
1140     freevars_seen: NodeMap<NodeMap<usize>>,
1141     pub export_map: ExportMap,
1142     pub trait_map: TraitMap,
1143
1144     // A map from nodes to anonymous modules.
1145     // Anonymous modules are pseudo-modules that are implicitly created around items
1146     // contained within blocks.
1147     //
1148     // For example, if we have this:
1149     //
1150     //  fn f() {
1151     //      fn g() {
1152     //          ...
1153     //      }
1154     //  }
1155     //
1156     // There will be an anonymous module created around `g` with the ID of the
1157     // entry block for `f`.
1158     block_map: NodeMap<Module<'a>>,
1159     module_map: FxHashMap<DefId, Module<'a>>,
1160     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1161
1162     pub make_glob_map: bool,
1163     // Maps imports to the names of items actually imported (this actually maps
1164     // all imports, but only glob imports are actually interesting).
1165     pub glob_map: GlobMap,
1166
1167     used_imports: FxHashSet<(NodeId, Namespace)>,
1168     pub maybe_unused_trait_imports: NodeSet,
1169
1170     privacy_errors: Vec<PrivacyError<'a>>,
1171     ambiguity_errors: Vec<AmbiguityError<'a>>,
1172     gated_errors: FxHashSet<Span>,
1173     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1174
1175     arenas: &'a ResolverArenas<'a>,
1176     dummy_binding: &'a NameBinding<'a>,
1177     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1178
1179     crate_loader: &'a mut CrateLoader,
1180     macro_names: FxHashSet<Name>,
1181     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1182     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1183     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1184     macro_defs: FxHashMap<Mark, DefId>,
1185     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1186     macro_exports: Vec<Export>,
1187     pub whitelisted_legacy_custom_derives: Vec<Name>,
1188     pub found_unresolved_macro: bool,
1189
1190     // List of crate local macros that we need to warn about as being unused.
1191     // Right now this only includes macro_rules! macros.
1192     unused_macros: FxHashSet<DefId>,
1193
1194     // Maps the `Mark` of an expansion to its containing module or block.
1195     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1196
1197     // Avoid duplicated errors for "name already defined".
1198     name_already_seen: FxHashMap<Name, Span>,
1199
1200     // If `#![feature(proc_macro)]` is set
1201     proc_macro_enabled: bool,
1202
1203     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1204     warned_proc_macros: FxHashSet<Name>,
1205
1206     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1207
1208     // This table maps struct IDs into struct constructor IDs,
1209     // it's not used during normal resolution, only for better error reporting.
1210     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1211 }
1212
1213 pub struct ResolverArenas<'a> {
1214     modules: arena::TypedArena<ModuleData<'a>>,
1215     local_modules: RefCell<Vec<Module<'a>>>,
1216     name_bindings: arena::TypedArena<NameBinding<'a>>,
1217     import_directives: arena::TypedArena<ImportDirective<'a>>,
1218     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1219     invocation_data: arena::TypedArena<InvocationData<'a>>,
1220     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1221 }
1222
1223 impl<'a> ResolverArenas<'a> {
1224     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1225         let module = self.modules.alloc(module);
1226         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1227             self.local_modules.borrow_mut().push(module);
1228         }
1229         module
1230     }
1231     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1232         self.local_modules.borrow()
1233     }
1234     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1235         self.name_bindings.alloc(name_binding)
1236     }
1237     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1238                               -> &'a ImportDirective {
1239         self.import_directives.alloc(import_directive)
1240     }
1241     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1242         self.name_resolutions.alloc(Default::default())
1243     }
1244     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1245                              -> &'a InvocationData<'a> {
1246         self.invocation_data.alloc(expansion_data)
1247     }
1248     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1249         self.legacy_bindings.alloc(binding)
1250     }
1251 }
1252
1253 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1254     fn parent(self, id: DefId) -> Option<DefId> {
1255         match id.krate {
1256             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1257             _ => self.session.cstore.def_key(id).parent,
1258         }.map(|index| DefId { index: index, ..id })
1259     }
1260 }
1261
1262 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1263     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1264         let namespace = if is_value { ValueNS } else { TypeNS };
1265         let hir::Path { ref segments, span, ref mut def } = *path;
1266         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1267         match self.resolve_path(&path, Some(namespace), true, span) {
1268             PathResult::Module(module) => *def = module.def().unwrap(),
1269             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1270                 *def = path_res.base_def(),
1271             PathResult::NonModule(..) => match self.resolve_path(&path, None, true, span) {
1272                 PathResult::Failed(msg, _) => {
1273                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1274                 }
1275                 _ => {}
1276             },
1277             PathResult::Indeterminate => unreachable!(),
1278             PathResult::Failed(msg, _) => {
1279                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1280             }
1281         }
1282     }
1283
1284     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1285         self.def_map.get(&id).cloned()
1286     }
1287
1288     fn definitions(&mut self) -> &mut Definitions {
1289         &mut self.definitions
1290     }
1291 }
1292
1293 impl<'a> Resolver<'a> {
1294     pub fn new(session: &'a Session,
1295                krate: &Crate,
1296                crate_name: &str,
1297                make_glob_map: MakeGlobMap,
1298                crate_loader: &'a mut CrateLoader,
1299                arenas: &'a ResolverArenas<'a>)
1300                -> Resolver<'a> {
1301         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1302         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1303         let graph_root = arenas.alloc_module(ModuleData {
1304             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1305             ..ModuleData::new(None, root_module_kind, root_def_id, krate.span)
1306         });
1307         let mut module_map = FxHashMap();
1308         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1309
1310         let mut definitions = Definitions::new();
1311         DefCollector::new(&mut definitions)
1312             .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
1313
1314         let mut invocations = FxHashMap();
1315         invocations.insert(Mark::root(),
1316                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1317
1318         let features = session.features.borrow();
1319
1320         let mut macro_defs = FxHashMap();
1321         macro_defs.insert(Mark::root(), root_def_id);
1322
1323         Resolver {
1324             session: session,
1325
1326             definitions: definitions,
1327
1328             // The outermost module has def ID 0; this is not reflected in the
1329             // AST.
1330             graph_root: graph_root,
1331             prelude: None,
1332
1333             trait_item_map: FxHashMap(),
1334             field_names: FxHashMap(),
1335
1336             determined_imports: Vec::new(),
1337             indeterminate_imports: Vec::new(),
1338
1339             current_module: graph_root,
1340             ribs: PerNS {
1341                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1342                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1343                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1344             },
1345             label_ribs: Vec::new(),
1346
1347             current_trait_ref: None,
1348             current_self_type: None,
1349
1350             primitive_type_table: PrimitiveTypeTable::new(),
1351
1352             def_map: NodeMap(),
1353             freevars: NodeMap(),
1354             freevars_seen: NodeMap(),
1355             export_map: NodeMap(),
1356             trait_map: NodeMap(),
1357             module_map: module_map,
1358             block_map: NodeMap(),
1359             extern_crate_roots: FxHashMap(),
1360
1361             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1362             glob_map: NodeMap(),
1363
1364             used_imports: FxHashSet(),
1365             maybe_unused_trait_imports: NodeSet(),
1366
1367             privacy_errors: Vec::new(),
1368             ambiguity_errors: Vec::new(),
1369             gated_errors: FxHashSet(),
1370             disallowed_shadowing: Vec::new(),
1371
1372             arenas: arenas,
1373             dummy_binding: arenas.alloc_name_binding(NameBinding {
1374                 kind: NameBindingKind::Def(Def::Err),
1375                 expansion: Mark::root(),
1376                 span: DUMMY_SP,
1377                 vis: ty::Visibility::Public,
1378             }),
1379
1380             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1381             use_extern_macros: features.use_extern_macros || features.proc_macro,
1382
1383             crate_loader: crate_loader,
1384             macro_names: FxHashSet(),
1385             global_macros: FxHashMap(),
1386             lexical_macro_resolutions: Vec::new(),
1387             macro_map: FxHashMap(),
1388             macro_exports: Vec::new(),
1389             invocations: invocations,
1390             macro_defs: macro_defs,
1391             local_macro_def_scopes: FxHashMap(),
1392             name_already_seen: FxHashMap(),
1393             whitelisted_legacy_custom_derives: Vec::new(),
1394             proc_macro_enabled: features.proc_macro,
1395             warned_proc_macros: FxHashSet(),
1396             potentially_unused_imports: Vec::new(),
1397             struct_constructors: DefIdMap(),
1398             found_unresolved_macro: false,
1399             unused_macros: FxHashSet(),
1400         }
1401     }
1402
1403     pub fn arenas() -> ResolverArenas<'a> {
1404         ResolverArenas {
1405             modules: arena::TypedArena::new(),
1406             local_modules: RefCell::new(Vec::new()),
1407             name_bindings: arena::TypedArena::new(),
1408             import_directives: arena::TypedArena::new(),
1409             name_resolutions: arena::TypedArena::new(),
1410             invocation_data: arena::TypedArena::new(),
1411             legacy_bindings: arena::TypedArena::new(),
1412         }
1413     }
1414
1415     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1416         PerNS {
1417             type_ns: f(self, TypeNS),
1418             value_ns: f(self, ValueNS),
1419             macro_ns: match self.use_extern_macros {
1420                 true => Some(f(self, MacroNS)),
1421                 false => None,
1422             },
1423         }
1424     }
1425
1426     /// Entry point to crate resolution.
1427     pub fn resolve_crate(&mut self, krate: &Crate) {
1428         ImportResolver { resolver: self }.finalize_imports();
1429         self.current_module = self.graph_root;
1430         self.finalize_current_module_macro_resolutions();
1431         visit::walk_crate(self, krate);
1432
1433         check_unused::check_crate(self, krate);
1434         self.report_errors();
1435         self.crate_loader.postprocess(krate);
1436     }
1437
1438     fn new_module(
1439         &self,
1440         parent: Module<'a>,
1441         kind: ModuleKind,
1442         normal_ancestor_id: DefId,
1443         span: Span,
1444     ) -> Module<'a> {
1445         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id, span))
1446     }
1447
1448     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1449                   -> bool /* true if an error was reported */ {
1450         match binding.kind {
1451             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1452                     if !used.get() => {
1453                 used.set(true);
1454                 directive.used.set(true);
1455                 if legacy_self_import {
1456                     self.warn_legacy_self_import(directive);
1457                     return false;
1458                 }
1459                 self.used_imports.insert((directive.id, ns));
1460                 self.add_to_glob_map(directive.id, ident);
1461                 self.record_use(ident, ns, binding, span)
1462             }
1463             NameBindingKind::Import { .. } => false,
1464             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1465                 self.ambiguity_errors.push(AmbiguityError {
1466                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1467                 });
1468                 if legacy {
1469                     self.record_use(ident, ns, b1, span);
1470                 }
1471                 !legacy
1472             }
1473             _ => false
1474         }
1475     }
1476
1477     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1478         if self.make_glob_map {
1479             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1480         }
1481     }
1482
1483     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1484     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1485     /// `ident` in the first scope that defines it (or None if no scopes define it).
1486     ///
1487     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1488     /// the items are defined in the block. For example,
1489     /// ```rust
1490     /// fn f() {
1491     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1492     ///    let g = || {};
1493     ///    fn g() {}
1494     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1495     /// }
1496     /// ```
1497     ///
1498     /// Invariant: This must only be called during main resolution, not during
1499     /// import resolution.
1500     fn resolve_ident_in_lexical_scope(&mut self,
1501                                       mut ident: Ident,
1502                                       ns: Namespace,
1503                                       record_used: bool,
1504                                       path_span: Span)
1505                                       -> Option<LexicalScopeBinding<'a>> {
1506         if ns == TypeNS {
1507             ident = ident.unhygienize();
1508         }
1509
1510         // Walk backwards up the ribs in scope.
1511         for i in (0 .. self.ribs[ns].len()).rev() {
1512             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1513                 // The ident resolves to a type parameter or local variable.
1514                 return Some(LexicalScopeBinding::Def(
1515                     self.adjust_local_def(ns, i, def, record_used, path_span)
1516                 ));
1517             }
1518
1519             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1520                 let item = self.resolve_ident_in_module(module, ident, ns, false,
1521                                                         record_used, path_span);
1522                 if let Ok(binding) = item {
1523                     // The ident resolves to an item.
1524                     return Some(LexicalScopeBinding::Item(binding));
1525                 }
1526
1527                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1528                 } else if !module.no_implicit_prelude {
1529                     return self.prelude.and_then(|prelude| {
1530                         self.resolve_ident_in_module(prelude, ident, ns, false,
1531                                                      false, path_span).ok()
1532                     }).map(LexicalScopeBinding::Item)
1533                 } else {
1534                     return None;
1535                 }
1536             }
1537
1538             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1539                 // If an invocation of this macro created `ident`, give up on `ident`
1540                 // and switch to `ident`'s source from the macro definition.
1541                 let ctxt_data = ident.ctxt.data();
1542                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1543                     ident.ctxt = ctxt_data.prev_ctxt;
1544                 }
1545             }
1546         }
1547
1548         None
1549     }
1550
1551     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext, span: Span) -> Module<'a> {
1552         let mut ctxt_data = crate_var_ctxt.data();
1553         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1554             ctxt_data = ctxt_data.prev_ctxt.data();
1555         }
1556         let module = self.macro_def_scope(ctxt_data.outer_mark, span);
1557         if module.is_local() { self.graph_root } else { module }
1558     }
1559
1560     // AST resolution
1561     //
1562     // We maintain a list of value ribs and type ribs.
1563     //
1564     // Simultaneously, we keep track of the current position in the module
1565     // graph in the `current_module` pointer. When we go to resolve a name in
1566     // the value or type namespaces, we first look through all the ribs and
1567     // then query the module graph. When we resolve a name in the module
1568     // namespace, we can skip all the ribs (since nested modules are not
1569     // allowed within blocks in Rust) and jump straight to the current module
1570     // graph node.
1571     //
1572     // Named implementations are handled separately. When we find a method
1573     // call, we consult the module node to find all of the implementations in
1574     // scope. This information is lazily cached in the module node. We then
1575     // generate a fake "implementation scope" containing all the
1576     // implementations thus found, for compatibility with old resolve pass.
1577
1578     fn with_scope<F>(&mut self, id: NodeId, f: F)
1579         where F: FnOnce(&mut Resolver)
1580     {
1581         let id = self.definitions.local_def_id(id);
1582         let module = self.module_map.get(&id).cloned(); // clones a reference
1583         if let Some(module) = module {
1584             // Move down in the graph.
1585             let orig_module = replace(&mut self.current_module, module);
1586             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1587             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1588
1589             self.finalize_current_module_macro_resolutions();
1590             f(self);
1591
1592             self.current_module = orig_module;
1593             self.ribs[ValueNS].pop();
1594             self.ribs[TypeNS].pop();
1595         } else {
1596             f(self);
1597         }
1598     }
1599
1600     /// Searches the current set of local scopes for labels.
1601     /// Stops after meeting a closure.
1602     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1603         for rib in self.label_ribs.iter().rev() {
1604             match rib.kind {
1605                 NormalRibKind => {
1606                     // Continue
1607                 }
1608                 MacroDefinition(def) => {
1609                     // If an invocation of this macro created `ident`, give up on `ident`
1610                     // and switch to `ident`'s source from the macro definition.
1611                     let ctxt_data = ident.ctxt.data();
1612                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1613                         ident.ctxt = ctxt_data.prev_ctxt;
1614                     }
1615                 }
1616                 _ => {
1617                     // Do not resolve labels across function boundary
1618                     return None;
1619                 }
1620             }
1621             let result = rib.bindings.get(&ident).cloned();
1622             if result.is_some() {
1623                 return result;
1624             }
1625         }
1626         None
1627     }
1628
1629     fn resolve_item(&mut self, item: &Item) {
1630         let name = item.ident.name;
1631
1632         debug!("(resolving item) resolving {}", name);
1633
1634         self.check_proc_macro_attrs(&item.attrs);
1635
1636         match item.node {
1637             ItemKind::Enum(_, ref generics) |
1638             ItemKind::Ty(_, ref generics) |
1639             ItemKind::Struct(_, ref generics) |
1640             ItemKind::Union(_, ref generics) |
1641             ItemKind::Fn(.., ref generics, _) => {
1642                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1643                                              |this| visit::walk_item(this, item));
1644             }
1645
1646             ItemKind::DefaultImpl(_, ref trait_ref) => {
1647                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1648                     // Resolve type arguments in trait path
1649                     visit::walk_trait_ref(this, trait_ref);
1650                 });
1651             }
1652             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1653                 self.resolve_implementation(generics,
1654                                             opt_trait_ref,
1655                                             &self_type,
1656                                             item.id,
1657                                             impl_items),
1658
1659             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1660                 // Create a new rib for the trait-wide type parameters.
1661                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1662                     let local_def_id = this.definitions.local_def_id(item.id);
1663                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1664                         this.visit_generics(generics);
1665                         walk_list!(this, visit_ty_param_bound, bounds);
1666
1667                         for trait_item in trait_items {
1668                             this.check_proc_macro_attrs(&trait_item.attrs);
1669
1670                             match trait_item.node {
1671                                 TraitItemKind::Const(ref ty, ref default) => {
1672                                     this.visit_ty(ty);
1673
1674                                     // Only impose the restrictions of
1675                                     // ConstRibKind for an actual constant
1676                                     // expression in a provided default.
1677                                     if let Some(ref expr) = *default{
1678                                         this.with_constant_rib(|this| {
1679                                             this.visit_expr(expr);
1680                                         });
1681                                     }
1682                                 }
1683                                 TraitItemKind::Method(ref sig, _) => {
1684                                     let type_parameters =
1685                                         HasTypeParameters(&sig.generics,
1686                                                           MethodRibKind(!sig.decl.has_self()));
1687                                     this.with_type_parameter_rib(type_parameters, |this| {
1688                                         visit::walk_trait_item(this, trait_item)
1689                                     });
1690                                 }
1691                                 TraitItemKind::Type(..) => {
1692                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1693                                         visit::walk_trait_item(this, trait_item)
1694                                     });
1695                                 }
1696                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1697                             };
1698                         }
1699                     });
1700                 });
1701             }
1702
1703             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1704                 self.with_scope(item.id, |this| {
1705                     visit::walk_item(this, item);
1706                 });
1707             }
1708
1709             ItemKind::Static(ref ty, _, ref expr) |
1710             ItemKind::Const(ref ty, ref expr) => {
1711                 self.with_item_rib(|this| {
1712                     this.visit_ty(ty);
1713                     this.with_constant_rib(|this| {
1714                         this.visit_expr(expr);
1715                     });
1716                 });
1717             }
1718
1719             ItemKind::Use(ref view_path) => {
1720                 match view_path.node {
1721                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1722                         // Resolve prefix of an import with empty braces (issue #28388).
1723                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1724                     }
1725                     _ => {}
1726                 }
1727             }
1728
1729             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(_)=> {
1730                 // do nothing, these are just around to be encoded
1731             }
1732
1733             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1734         }
1735     }
1736
1737     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1738         where F: FnOnce(&mut Resolver)
1739     {
1740         match type_parameters {
1741             HasTypeParameters(generics, rib_kind) => {
1742                 let mut function_type_rib = Rib::new(rib_kind);
1743                 let mut seen_bindings = FxHashMap();
1744                 for type_parameter in &generics.ty_params {
1745                     let name = type_parameter.ident.name;
1746                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1747
1748                     if seen_bindings.contains_key(&name) {
1749                         let span = seen_bindings.get(&name).unwrap();
1750                         resolve_error(self,
1751                                       type_parameter.span,
1752                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1753                                                                                           span));
1754                     }
1755                     seen_bindings.entry(name).or_insert(type_parameter.span);
1756
1757                     // plain insert (no renaming)
1758                     let def_id = self.definitions.local_def_id(type_parameter.id);
1759                     let def = Def::TyParam(def_id);
1760                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1761                     self.record_def(type_parameter.id, PathResolution::new(def));
1762                 }
1763                 self.ribs[TypeNS].push(function_type_rib);
1764             }
1765
1766             NoTypeParameters => {
1767                 // Nothing to do.
1768             }
1769         }
1770
1771         f(self);
1772
1773         if let HasTypeParameters(..) = type_parameters {
1774             self.ribs[TypeNS].pop();
1775         }
1776     }
1777
1778     fn with_label_rib<F>(&mut self, f: F)
1779         where F: FnOnce(&mut Resolver)
1780     {
1781         self.label_ribs.push(Rib::new(NormalRibKind));
1782         f(self);
1783         self.label_ribs.pop();
1784     }
1785
1786     fn with_item_rib<F>(&mut self, f: F)
1787         where F: FnOnce(&mut Resolver)
1788     {
1789         self.ribs[ValueNS].push(Rib::new(ItemRibKind));
1790         self.ribs[TypeNS].push(Rib::new(ItemRibKind));
1791         f(self);
1792         self.ribs[TypeNS].pop();
1793         self.ribs[ValueNS].pop();
1794     }
1795
1796     fn with_constant_rib<F>(&mut self, f: F)
1797         where F: FnOnce(&mut Resolver)
1798     {
1799         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1800         f(self);
1801         self.ribs[ValueNS].pop();
1802     }
1803
1804     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1805         where F: FnOnce(&mut Resolver) -> T
1806     {
1807         // Handle nested impls (inside fn bodies)
1808         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1809         let result = f(self);
1810         self.current_self_type = previous_value;
1811         result
1812     }
1813
1814     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1815         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1816     {
1817         let mut new_val = None;
1818         let mut new_id = None;
1819         if let Some(trait_ref) = opt_trait_ref {
1820             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1821                                               &trait_ref.path, PathSource::Trait).base_def();
1822             if def != Def::Err {
1823                 new_val = Some((def.def_id(), trait_ref.clone()));
1824                 new_id = Some(def.def_id());
1825             }
1826         }
1827         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1828         let result = f(self, new_id);
1829         self.current_trait_ref = original_trait_ref;
1830         result
1831     }
1832
1833     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1834         where F: FnOnce(&mut Resolver)
1835     {
1836         let mut self_type_rib = Rib::new(NormalRibKind);
1837
1838         // plain insert (no renaming, types are not currently hygienic....)
1839         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1840         self.ribs[TypeNS].push(self_type_rib);
1841         f(self);
1842         self.ribs[TypeNS].pop();
1843     }
1844
1845     fn resolve_implementation(&mut self,
1846                               generics: &Generics,
1847                               opt_trait_reference: &Option<TraitRef>,
1848                               self_type: &Ty,
1849                               item_id: NodeId,
1850                               impl_items: &[ImplItem]) {
1851         // If applicable, create a rib for the type parameters.
1852         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1853             // Dummy self type for better errors if `Self` is used in the trait path.
1854             this.with_self_rib(Def::SelfTy(None, None), |this| {
1855                 // Resolve the trait reference, if necessary.
1856                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1857                     let item_def_id = this.definitions.local_def_id(item_id);
1858                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1859                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1860                             // Resolve type arguments in trait path
1861                             visit::walk_trait_ref(this, trait_ref);
1862                         }
1863                         // Resolve the self type.
1864                         this.visit_ty(self_type);
1865                         // Resolve the type parameters.
1866                         this.visit_generics(generics);
1867                         this.with_current_self_type(self_type, |this| {
1868                             for impl_item in impl_items {
1869                                 this.check_proc_macro_attrs(&impl_item.attrs);
1870                                 this.resolve_visibility(&impl_item.vis);
1871                                 match impl_item.node {
1872                                     ImplItemKind::Const(..) => {
1873                                         // If this is a trait impl, ensure the const
1874                                         // exists in trait
1875                                         this.check_trait_item(impl_item.ident.name,
1876                                                             ValueNS,
1877                                                             impl_item.span,
1878                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1879                                         visit::walk_impl_item(this, impl_item);
1880                                     }
1881                                     ImplItemKind::Method(ref sig, _) => {
1882                                         // If this is a trait impl, ensure the method
1883                                         // exists in trait
1884                                         this.check_trait_item(impl_item.ident.name,
1885                                                             ValueNS,
1886                                                             impl_item.span,
1887                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1888
1889                                         // We also need a new scope for the method-
1890                                         // specific type parameters.
1891                                         let type_parameters =
1892                                             HasTypeParameters(&sig.generics,
1893                                                             MethodRibKind(!sig.decl.has_self()));
1894                                         this.with_type_parameter_rib(type_parameters, |this| {
1895                                             visit::walk_impl_item(this, impl_item);
1896                                         });
1897                                     }
1898                                     ImplItemKind::Type(ref ty) => {
1899                                         // If this is a trait impl, ensure the type
1900                                         // exists in trait
1901                                         this.check_trait_item(impl_item.ident.name,
1902                                                             TypeNS,
1903                                                             impl_item.span,
1904                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1905
1906                                         this.visit_ty(ty);
1907                                     }
1908                                     ImplItemKind::Macro(_) =>
1909                                         panic!("unexpanded macro in resolve!"),
1910                                 }
1911                             }
1912                         });
1913                     });
1914                 });
1915             });
1916         });
1917     }
1918
1919     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1920         where F: FnOnce(Name, &str) -> ResolutionError
1921     {
1922         // If there is a TraitRef in scope for an impl, then the method must be in the
1923         // trait.
1924         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1925             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1926                 let path_str = path_names_to_string(&trait_ref.path);
1927                 resolve_error(self, span, err(name, &path_str));
1928             }
1929         }
1930     }
1931
1932     fn resolve_local(&mut self, local: &Local) {
1933         // Resolve the type.
1934         walk_list!(self, visit_ty, &local.ty);
1935
1936         // Resolve the initializer.
1937         walk_list!(self, visit_expr, &local.init);
1938
1939         // Resolve the pattern.
1940         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1941     }
1942
1943     // build a map from pattern identifiers to binding-info's.
1944     // this is done hygienically. This could arise for a macro
1945     // that expands into an or-pattern where one 'x' was from the
1946     // user and one 'x' came from the macro.
1947     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1948         let mut binding_map = FxHashMap();
1949
1950         pat.walk(&mut |pat| {
1951             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1952                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1953                     Some(Def::Local(..)) => true,
1954                     _ => false,
1955                 } {
1956                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1957                     binding_map.insert(ident.node, binding_info);
1958                 }
1959             }
1960             true
1961         });
1962
1963         binding_map
1964     }
1965
1966     // check that all of the arms in an or-pattern have exactly the
1967     // same set of bindings, with the same binding modes for each.
1968     fn check_consistent_bindings(&mut self, arm: &Arm) {
1969         if arm.pats.is_empty() {
1970             return;
1971         }
1972
1973         let mut missing_vars = FxHashMap();
1974         let mut inconsistent_vars = FxHashMap();
1975         for (i, p) in arm.pats.iter().enumerate() {
1976             let map_i = self.binding_mode_map(&p);
1977
1978             for (j, q) in arm.pats.iter().enumerate() {
1979                 if i == j {
1980                     continue;
1981                 }
1982
1983                 let map_j = self.binding_mode_map(&q);
1984                 for (&key, &binding_i) in &map_i {
1985                     if map_j.len() == 0 {                   // Account for missing bindings when
1986                         let binding_error = missing_vars    // map_j has none.
1987                             .entry(key.name)
1988                             .or_insert(BindingError {
1989                                 name: key.name,
1990                                 origin: BTreeSet::new(),
1991                                 target: BTreeSet::new(),
1992                             });
1993                         binding_error.origin.insert(binding_i.span);
1994                         binding_error.target.insert(q.span);
1995                     }
1996                     for (&key_j, &binding_j) in &map_j {
1997                         match map_i.get(&key_j) {
1998                             None => {  // missing binding
1999                                 let binding_error = missing_vars
2000                                     .entry(key_j.name)
2001                                     .or_insert(BindingError {
2002                                         name: key_j.name,
2003                                         origin: BTreeSet::new(),
2004                                         target: BTreeSet::new(),
2005                                     });
2006                                 binding_error.origin.insert(binding_j.span);
2007                                 binding_error.target.insert(p.span);
2008                             }
2009                             Some(binding_i) => {  // check consistent binding
2010                                 if binding_i.binding_mode != binding_j.binding_mode {
2011                                     inconsistent_vars
2012                                         .entry(key.name)
2013                                         .or_insert((binding_j.span, binding_i.span));
2014                                 }
2015                             }
2016                         }
2017                     }
2018                 }
2019             }
2020         }
2021         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
2022         missing_vars.sort();
2023         for (_, v) in missing_vars {
2024             resolve_error(self,
2025                           *v.origin.iter().next().unwrap(),
2026                           ResolutionError::VariableNotBoundInPattern(v));
2027         }
2028         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2029         inconsistent_vars.sort();
2030         for (name, v) in inconsistent_vars {
2031             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2032         }
2033     }
2034
2035     fn resolve_arm(&mut self, arm: &Arm) {
2036         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2037
2038         let mut bindings_list = FxHashMap();
2039         for pattern in &arm.pats {
2040             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2041         }
2042
2043         // This has to happen *after* we determine which
2044         // pat_idents are variants
2045         self.check_consistent_bindings(arm);
2046
2047         walk_list!(self, visit_expr, &arm.guard);
2048         self.visit_expr(&arm.body);
2049
2050         self.ribs[ValueNS].pop();
2051     }
2052
2053     fn resolve_block(&mut self, block: &Block) {
2054         debug!("(resolving block) entering block");
2055         // Move down in the graph, if there's an anonymous module rooted here.
2056         let orig_module = self.current_module;
2057         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2058
2059         let mut num_macro_definition_ribs = 0;
2060         if let Some(anonymous_module) = anonymous_module {
2061             debug!("(resolving block) found anonymous module, moving down");
2062             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2063             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2064             self.current_module = anonymous_module;
2065             self.finalize_current_module_macro_resolutions();
2066         } else {
2067             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2068         }
2069
2070         // Descend into the block.
2071         for stmt in &block.stmts {
2072             if let ast::StmtKind::Item(ref item) = stmt.node {
2073                 if let ast::ItemKind::MacroDef(..) = item.node {
2074                     num_macro_definition_ribs += 1;
2075                     let def = self.definitions.local_def_id(item.id);
2076                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2077                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2078                 }
2079             }
2080
2081             self.visit_stmt(stmt);
2082         }
2083
2084         // Move back up.
2085         self.current_module = orig_module;
2086         for _ in 0 .. num_macro_definition_ribs {
2087             self.ribs[ValueNS].pop();
2088             self.label_ribs.pop();
2089         }
2090         self.ribs[ValueNS].pop();
2091         if let Some(_) = anonymous_module {
2092             self.ribs[TypeNS].pop();
2093         }
2094         debug!("(resolving block) leaving block");
2095     }
2096
2097     fn fresh_binding(&mut self,
2098                      ident: &SpannedIdent,
2099                      pat_id: NodeId,
2100                      outer_pat_id: NodeId,
2101                      pat_src: PatternSource,
2102                      bindings: &mut FxHashMap<Ident, NodeId>)
2103                      -> PathResolution {
2104         // Add the binding to the local ribs, if it
2105         // doesn't already exist in the bindings map. (We
2106         // must not add it if it's in the bindings map
2107         // because that breaks the assumptions later
2108         // passes make about or-patterns.)
2109         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2110         match bindings.get(&ident.node).cloned() {
2111             Some(id) if id == outer_pat_id => {
2112                 // `Variant(a, a)`, error
2113                 resolve_error(
2114                     self,
2115                     ident.span,
2116                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2117                         &ident.node.name.as_str())
2118                 );
2119             }
2120             Some(..) if pat_src == PatternSource::FnParam => {
2121                 // `fn f(a: u8, a: u8)`, error
2122                 resolve_error(
2123                     self,
2124                     ident.span,
2125                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2126                         &ident.node.name.as_str())
2127                 );
2128             }
2129             Some(..) if pat_src == PatternSource::Match => {
2130                 // `Variant1(a) | Variant2(a)`, ok
2131                 // Reuse definition from the first `a`.
2132                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2133             }
2134             Some(..) => {
2135                 span_bug!(ident.span, "two bindings with the same name from \
2136                                        unexpected pattern source {:?}", pat_src);
2137             }
2138             None => {
2139                 // A completely fresh binding, add to the lists if it's valid.
2140                 if ident.node.name != keywords::Invalid.name() {
2141                     bindings.insert(ident.node, outer_pat_id);
2142                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2143                 }
2144             }
2145         }
2146
2147         PathResolution::new(def)
2148     }
2149
2150     fn resolve_pattern(&mut self,
2151                        pat: &Pat,
2152                        pat_src: PatternSource,
2153                        // Maps idents to the node ID for the
2154                        // outermost pattern that binds them.
2155                        bindings: &mut FxHashMap<Ident, NodeId>) {
2156         // Visit all direct subpatterns of this pattern.
2157         let outer_pat_id = pat.id;
2158         pat.walk(&mut |pat| {
2159             match pat.node {
2160                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2161                     // First try to resolve the identifier as some existing
2162                     // entity, then fall back to a fresh binding.
2163                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS,
2164                                                                       false, pat.span)
2165                                       .and_then(LexicalScopeBinding::item);
2166                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2167                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2168                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2169                         match def {
2170                             Def::StructCtor(_, CtorKind::Const) |
2171                             Def::VariantCtor(_, CtorKind::Const) |
2172                             Def::Const(..) if !always_binding => {
2173                                 // A unit struct/variant or constant pattern.
2174                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2175                                 Some(PathResolution::new(def))
2176                             }
2177                             Def::StructCtor(..) | Def::VariantCtor(..) |
2178                             Def::Const(..) | Def::Static(..) => {
2179                                 // A fresh binding that shadows something unacceptable.
2180                                 resolve_error(
2181                                     self,
2182                                     ident.span,
2183                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2184                                         pat_src.descr(), ident.node.name, binding.unwrap())
2185                                 );
2186                                 None
2187                             }
2188                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2189                                 // These entities are explicitly allowed
2190                                 // to be shadowed by fresh bindings.
2191                                 None
2192                             }
2193                             def => {
2194                                 span_bug!(ident.span, "unexpected definition for an \
2195                                                        identifier in pattern: {:?}", def);
2196                             }
2197                         }
2198                     }).unwrap_or_else(|| {
2199                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2200                     });
2201
2202                     self.record_def(pat.id, resolution);
2203                 }
2204
2205                 PatKind::TupleStruct(ref path, ..) => {
2206                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2207                 }
2208
2209                 PatKind::Path(ref qself, ref path) => {
2210                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2211                 }
2212
2213                 PatKind::Struct(ref path, ..) => {
2214                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2215                 }
2216
2217                 _ => {}
2218             }
2219             true
2220         });
2221
2222         visit::walk_pat(self, pat);
2223     }
2224
2225     // High-level and context dependent path resolution routine.
2226     // Resolves the path and records the resolution into definition map.
2227     // If resolution fails tries several techniques to find likely
2228     // resolution candidates, suggest imports or other help, and report
2229     // errors in user friendly way.
2230     fn smart_resolve_path(&mut self,
2231                           id: NodeId,
2232                           qself: Option<&QSelf>,
2233                           path: &Path,
2234                           source: PathSource)
2235                           -> PathResolution {
2236         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2237         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2238         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2239     }
2240
2241     fn smart_resolve_path_fragment(&mut self,
2242                                    id: NodeId,
2243                                    qself: Option<&QSelf>,
2244                                    path: &[Ident],
2245                                    span: Span,
2246                                    ident_span: Span,
2247                                    source: PathSource)
2248                                    -> PathResolution {
2249         let ns = source.namespace();
2250         let is_expected = &|def| source.is_expected(def);
2251         let is_enum_variant = &|def| if let Def::Variant(..) = def { true } else { false };
2252
2253         // Base error is amended with one short label and possibly some longer helps/notes.
2254         let report_errors = |this: &mut Self, def: Option<Def>| {
2255             // Make the base error.
2256             let expected = source.descr_expected();
2257             let path_str = names_to_string(path);
2258             let code = source.error_code(def.is_some());
2259             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2260                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2261                  format!("not a {}", expected), span)
2262             } else {
2263                 let item_str = path[path.len() - 1];
2264                 let (mod_prefix, mod_str) = if path.len() == 1 {
2265                     (format!(""), format!("this scope"))
2266                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2267                     (format!(""), format!("the crate root"))
2268                 } else {
2269                     let mod_path = &path[..path.len() - 1];
2270                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), false, span) {
2271                         PathResult::Module(module) => module.def(),
2272                         _ => None,
2273                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2274                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2275                 };
2276                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2277                  format!("not found in {}", mod_str), ident_span)
2278             };
2279             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2280
2281             // Emit special messages for unresolved `Self` and `self`.
2282             if is_self_type(path, ns) {
2283                 __diagnostic_used!(E0411);
2284                 err.code("E0411".into());
2285                 err.span_label(span, "`Self` is only available in traits and impls");
2286                 return err;
2287             }
2288             if is_self_value(path, ns) {
2289                 __diagnostic_used!(E0424);
2290                 err.code("E0424".into());
2291                 err.span_label(span, format!("`self` value is only available in \
2292                                                methods with `self` parameter"));
2293                 return err;
2294             }
2295
2296             // Try to lookup the name in more relaxed fashion for better error reporting.
2297             let name = path.last().unwrap().name;
2298             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2299             if !candidates.is_empty() {
2300                 let mut module_span = this.current_module.span;
2301                 module_span.hi = module_span.lo;
2302                 // Report import candidates as help and proceed searching for labels.
2303                 show_candidates(&mut err, module_span, &candidates, def.is_some());
2304             } else if is_expected(Def::Enum(DefId::local(CRATE_DEF_INDEX))) {
2305                 let enum_candidates = this.lookup_import_candidates(name, ns, is_enum_variant);
2306                 let mut enum_candidates = enum_candidates.iter()
2307                     .map(|suggestion| import_candidate_to_paths(&suggestion)).collect::<Vec<_>>();
2308                 enum_candidates.sort();
2309                 for (sp, variant_path, enum_path) in enum_candidates {
2310                     let msg = format!("there is an enum variant `{}`, did you mean to use `{}`?",
2311                                       variant_path,
2312                                       enum_path);
2313                     if sp == DUMMY_SP {
2314                         err.help(&msg);
2315                     } else {
2316                         err.span_help(sp, &msg);
2317                     }
2318                 }
2319             }
2320             if path.len() == 1 && this.self_type_is_available(span) {
2321                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2322                     let self_is_available = this.self_value_is_available(path[0].ctxt, span);
2323                     match candidate {
2324                         AssocSuggestion::Field => {
2325                             err.span_label(span, format!("did you mean `self.{}`?", path_str));
2326                             if !self_is_available {
2327                                 err.span_label(span, format!("`self` value is only available in \
2328                                                                methods with `self` parameter"));
2329                             }
2330                         }
2331                         AssocSuggestion::MethodWithSelf if self_is_available => {
2332                             err.span_label(span, format!("did you mean `self.{}(...)`?",
2333                                                            path_str));
2334                         }
2335                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2336                             err.span_label(span, format!("did you mean `Self::{}`?", path_str));
2337                         }
2338                     }
2339                     return err;
2340                 }
2341             }
2342
2343             let mut levenshtein_worked = false;
2344
2345             // Try Levenshtein.
2346             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected, span) {
2347                 err.span_label(ident_span, format!("did you mean `{}`?", candidate));
2348                 levenshtein_worked = true;
2349             }
2350
2351             // Try context dependent help if relaxed lookup didn't work.
2352             if let Some(def) = def {
2353                 match (def, source) {
2354                     (Def::Macro(..), _) => {
2355                         err.span_label(span, format!("did you mean `{}!(...)`?", path_str));
2356                         return err;
2357                     }
2358                     (Def::TyAlias(..), PathSource::Trait) => {
2359                         err.span_label(span, "type aliases cannot be used for traits");
2360                         return err;
2361                     }
2362                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2363                         ExprKind::Field(_, ident) => {
2364                             err.span_label(parent.span, format!("did you mean `{}::{}`?",
2365                                                                  path_str, ident.node));
2366                             return err;
2367                         }
2368                         ExprKind::MethodCall(ident, ..) => {
2369                             err.span_label(parent.span, format!("did you mean `{}::{}(...)`?",
2370                                                                  path_str, ident.node));
2371                             return err;
2372                         }
2373                         _ => {}
2374                     },
2375                     _ if ns == ValueNS && is_struct_like(def) => {
2376                         if let Def::Struct(def_id) = def {
2377                             if let Some((ctor_def, ctor_vis))
2378                                     = this.struct_constructors.get(&def_id).cloned() {
2379                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2380                                     err.span_label(span, format!("constructor is not visible \
2381                                                                    here due to private fields"));
2382                                 }
2383                             }
2384                         }
2385                         err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?",
2386                                                        path_str));
2387                         return err;
2388                     }
2389                     _ => {}
2390                 }
2391             }
2392
2393             // Fallback label.
2394             if !levenshtein_worked {
2395                 err.span_label(base_span, fallback_label);
2396             }
2397             err
2398         };
2399         let report_errors = |this: &mut Self, def: Option<Def>| {
2400             report_errors(this, def).emit();
2401             err_path_resolution()
2402         };
2403
2404         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2405                                                            source.defer_to_typeck(),
2406                                                            source.global_by_default()) {
2407             Some(resolution) if resolution.unresolved_segments() == 0 => {
2408                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2409                     resolution
2410                 } else {
2411                     // Add a temporary hack to smooth the transition to new struct ctor
2412                     // visibility rules. See #38932 for more details.
2413                     let mut res = None;
2414                     if let Def::Struct(def_id) = resolution.base_def() {
2415                         if let Some((ctor_def, ctor_vis))
2416                                 = self.struct_constructors.get(&def_id).cloned() {
2417                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2418                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2419                                 self.session.add_lint(lint, id, span,
2420                                     "private struct constructors are not usable through \
2421                                      reexports in outer modules".to_string());
2422                                 res = Some(PathResolution::new(ctor_def));
2423                             }
2424                         }
2425                     }
2426
2427                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2428                 }
2429             }
2430             Some(resolution) if source.defer_to_typeck() => {
2431                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2432                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2433                 // it needs to be added to the trait map.
2434                 if ns == ValueNS {
2435                     let item_name = path.last().unwrap().name;
2436                     let traits = self.get_traits_containing_item(item_name, ns);
2437                     self.trait_map.insert(id, traits);
2438                 }
2439                 resolution
2440             }
2441             _ => report_errors(self, None)
2442         };
2443
2444         if let PathSource::TraitItem(..) = source {} else {
2445             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2446             self.record_def(id, resolution);
2447         }
2448         resolution
2449     }
2450
2451     fn self_type_is_available(&mut self, span: Span) -> bool {
2452         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(),
2453                                                           TypeNS, false, span);
2454         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2455     }
2456
2457     fn self_value_is_available(&mut self, ctxt: SyntaxContext, span: Span) -> bool {
2458         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2459         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, false, span);
2460         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2461     }
2462
2463     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2464     fn resolve_qpath_anywhere(&mut self,
2465                               id: NodeId,
2466                               qself: Option<&QSelf>,
2467                               path: &[Ident],
2468                               primary_ns: Namespace,
2469                               span: Span,
2470                               defer_to_typeck: bool,
2471                               global_by_default: bool)
2472                               -> Option<PathResolution> {
2473         let mut fin_res = None;
2474         // FIXME: can't resolve paths in macro namespace yet, macros are
2475         // processed by the little special hack below.
2476         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2477             if i == 0 || ns != primary_ns {
2478                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2479                     // If defer_to_typeck, then resolution > no resolution,
2480                     // otherwise full resolution > partial resolution > no resolution.
2481                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2482                         return Some(res),
2483                     res => if fin_res.is_none() { fin_res = res },
2484                 };
2485             }
2486         }
2487         let is_global = self.global_macros.get(&path[0].name).cloned()
2488             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2489         if primary_ns != MacroNS && (is_global || self.macro_names.contains(&path[0].name)) {
2490             // Return some dummy definition, it's enough for error reporting.
2491             return Some(
2492                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2493             );
2494         }
2495         fin_res
2496     }
2497
2498     /// Handles paths that may refer to associated items.
2499     fn resolve_qpath(&mut self,
2500                      id: NodeId,
2501                      qself: Option<&QSelf>,
2502                      path: &[Ident],
2503                      ns: Namespace,
2504                      span: Span,
2505                      global_by_default: bool)
2506                      -> Option<PathResolution> {
2507         if let Some(qself) = qself {
2508             if qself.position == 0 {
2509                 // FIXME: Create some fake resolution that can't possibly be a type.
2510                 return Some(PathResolution::with_unresolved_segments(
2511                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2512                 ));
2513             }
2514             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2515             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2516             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2517                                                        span, span, PathSource::TraitItem(ns));
2518             return Some(PathResolution::with_unresolved_segments(
2519                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2520             ));
2521         }
2522
2523         let result = match self.resolve_path(&path, Some(ns), true, span) {
2524             PathResult::NonModule(path_res) => path_res,
2525             PathResult::Module(module) if !module.is_normal() => {
2526                 PathResolution::new(module.def().unwrap())
2527             }
2528             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2529             // don't report an error right away, but try to fallback to a primitive type.
2530             // So, we are still able to successfully resolve something like
2531             //
2532             // use std::u8; // bring module u8 in scope
2533             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2534             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2535             //                     // not to non-existent std::u8::max_value
2536             // }
2537             //
2538             // Such behavior is required for backward compatibility.
2539             // The same fallback is used when `a` resolves to nothing.
2540             PathResult::Module(..) | PathResult::Failed(..)
2541                     if (ns == TypeNS || path.len() > 1) &&
2542                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2543                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2544                 match prim {
2545                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2546                         if !self.session.features.borrow().i128_type {
2547                             emit_feature_err(&self.session.parse_sess,
2548                                                 "i128_type", span, GateIssue::Language,
2549                                                 "128-bit type is unstable");
2550
2551                         }
2552                     }
2553                     _ => {}
2554                 }
2555                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2556             }
2557             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2558             PathResult::Failed(msg, false) => {
2559                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2560                 err_path_resolution()
2561             }
2562             PathResult::Failed(..) => return None,
2563             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2564         };
2565
2566         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2567            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2568             let unqualified_result = {
2569                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), false, span) {
2570                     PathResult::NonModule(path_res) => path_res.base_def(),
2571                     PathResult::Module(module) => module.def().unwrap(),
2572                     _ => return Some(result),
2573                 }
2574             };
2575             if result.base_def() == unqualified_result {
2576                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2577                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2578             }
2579         }
2580
2581         Some(result)
2582     }
2583
2584     fn resolve_path(&mut self,
2585                     path: &[Ident],
2586                     opt_ns: Option<Namespace>, // `None` indicates a module path
2587                     record_used: bool,
2588                     path_span: Span)
2589                     -> PathResult<'a> {
2590         let mut module = None;
2591         let mut allow_super = true;
2592
2593         for (i, &ident) in path.iter().enumerate() {
2594             let is_last = i == path.len() - 1;
2595             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2596
2597             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2598                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2599                 continue
2600             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2601                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2602                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2603                 if let Some(parent) = self_module.parent {
2604                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2605                     continue
2606                 } else {
2607                     let msg = "There are too many initial `super`s.".to_string();
2608                     return PathResult::Failed(msg, false);
2609                 }
2610             }
2611             allow_super = false;
2612
2613             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2614                 module = Some(self.graph_root);
2615                 continue
2616             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2617                 module = Some(self.resolve_crate_var(ident.ctxt, path_span));
2618                 continue
2619             }
2620
2621             let binding = if let Some(module) = module {
2622                 self.resolve_ident_in_module(module, ident, ns, false, record_used, path_span)
2623             } else if opt_ns == Some(MacroNS) {
2624                 self.resolve_lexical_macro_path_segment(ident, ns, record_used, path_span)
2625                     .map(MacroBinding::binding)
2626             } else {
2627                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used, path_span) {
2628                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2629                     Some(LexicalScopeBinding::Def(def))
2630                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2631                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2632                             def, path.len() - 1
2633                         ));
2634                     }
2635                     _ => Err(if record_used { Determined } else { Undetermined }),
2636                 }
2637             };
2638
2639             match binding {
2640                 Ok(binding) => {
2641                     let def = binding.def();
2642                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2643                     if let Some(next_module) = binding.module() {
2644                         module = Some(next_module);
2645                     } else if def == Def::Err {
2646                         return PathResult::NonModule(err_path_resolution());
2647                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2648                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2649                             def, path.len() - i - 1
2650                         ));
2651                     } else {
2652                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2653                     }
2654                 }
2655                 Err(Undetermined) => return PathResult::Indeterminate,
2656                 Err(Determined) => {
2657                     if let Some(module) = module {
2658                         if opt_ns.is_some() && !module.is_normal() {
2659                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2660                                 module.def().unwrap(), path.len() - i
2661                             ));
2662                         }
2663                     }
2664                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2665                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2666                         let mut candidates =
2667                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2668                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2669                         if let Some(candidate) = candidates.get(0) {
2670                             format!("Did you mean `{}`?", candidate.path)
2671                         } else {
2672                             format!("Maybe a missing `extern crate {};`?", ident)
2673                         }
2674                     } else if i == 0 {
2675                         format!("Use of undeclared type or module `{}`", ident)
2676                     } else {
2677                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2678                     };
2679                     return PathResult::Failed(msg, is_last);
2680                 }
2681             }
2682         }
2683
2684         PathResult::Module(module.unwrap_or(self.graph_root))
2685     }
2686
2687     // Resolve a local definition, potentially adjusting for closures.
2688     fn adjust_local_def(&mut self,
2689                         ns: Namespace,
2690                         rib_index: usize,
2691                         mut def: Def,
2692                         record_used: bool,
2693                         span: Span) -> Def {
2694         let ribs = &self.ribs[ns][rib_index + 1..];
2695
2696         // An invalid forward use of a type parameter from a previous default.
2697         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2698             if record_used {
2699                 resolve_error(self, span,
2700                         ResolutionError::ForwardDeclaredTyParam);
2701             }
2702             assert_eq!(def, Def::Err);
2703             return Def::Err;
2704         }
2705
2706         match def {
2707             Def::Upvar(..) => {
2708                 span_bug!(span, "unexpected {:?} in bindings", def)
2709             }
2710             Def::Local(def_id) => {
2711                 for rib in ribs {
2712                     match rib.kind {
2713                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2714                         ForwardTyParamBanRibKind => {
2715                             // Nothing to do. Continue.
2716                         }
2717                         ClosureRibKind(function_id) => {
2718                             let prev_def = def;
2719                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2720
2721                             let seen = self.freevars_seen
2722                                            .entry(function_id)
2723                                            .or_insert_with(|| NodeMap());
2724                             if let Some(&index) = seen.get(&node_id) {
2725                                 def = Def::Upvar(def_id, index, function_id);
2726                                 continue;
2727                             }
2728                             let vec = self.freevars
2729                                           .entry(function_id)
2730                                           .or_insert_with(|| vec![]);
2731                             let depth = vec.len();
2732                             def = Def::Upvar(def_id, depth, function_id);
2733
2734                             if record_used {
2735                                 vec.push(Freevar {
2736                                     def: prev_def,
2737                                     span: span,
2738                                 });
2739                                 seen.insert(node_id, depth);
2740                             }
2741                         }
2742                         ItemRibKind | MethodRibKind(_) => {
2743                             // This was an attempt to access an upvar inside a
2744                             // named function item. This is not allowed, so we
2745                             // report an error.
2746                             if record_used {
2747                                 resolve_error(self, span,
2748                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2749                             }
2750                             return Def::Err;
2751                         }
2752                         ConstantItemRibKind => {
2753                             // Still doesn't deal with upvars
2754                             if record_used {
2755                                 resolve_error(self, span,
2756                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2757                             }
2758                             return Def::Err;
2759                         }
2760                     }
2761                 }
2762             }
2763             Def::TyParam(..) | Def::SelfTy(..) => {
2764                 for rib in ribs {
2765                     match rib.kind {
2766                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2767                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2768                         ConstantItemRibKind => {
2769                             // Nothing to do. Continue.
2770                         }
2771                         ItemRibKind => {
2772                             // This was an attempt to use a type parameter outside
2773                             // its scope.
2774                             if record_used {
2775                                 resolve_error(self, span,
2776                                               ResolutionError::TypeParametersFromOuterFunction);
2777                             }
2778                             return Def::Err;
2779                         }
2780                     }
2781                 }
2782             }
2783             _ => {}
2784         }
2785         return def;
2786     }
2787
2788     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2789     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2790     // FIXME #34673: This needs testing.
2791     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2792         where F: FnOnce(&mut Resolver<'a>) -> T,
2793     {
2794         self.with_empty_ribs(|this| {
2795             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2796             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2797             f(this)
2798         })
2799     }
2800
2801     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2802         where F: FnOnce(&mut Resolver<'a>) -> T,
2803     {
2804         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2805         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2806
2807         let result = f(self);
2808         self.ribs = ribs;
2809         self.label_ribs = label_ribs;
2810         result
2811     }
2812
2813     fn lookup_assoc_candidate<FilterFn>(&mut self,
2814                                         name: Name,
2815                                         ns: Namespace,
2816                                         filter_fn: FilterFn)
2817                                         -> Option<AssocSuggestion>
2818         where FilterFn: Fn(Def) -> bool
2819     {
2820         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2821             match t.node {
2822                 TyKind::Path(None, _) => Some(t.id),
2823                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2824                 // This doesn't handle the remaining `Ty` variants as they are not
2825                 // that commonly the self_type, it might be interesting to provide
2826                 // support for those in future.
2827                 _ => None,
2828             }
2829         }
2830
2831         // Fields are generally expected in the same contexts as locals.
2832         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2833             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2834                 // Look for a field with the same name in the current self_type.
2835                 if let Some(resolution) = self.def_map.get(&node_id) {
2836                     match resolution.base_def() {
2837                         Def::Struct(did) | Def::Union(did)
2838                                 if resolution.unresolved_segments() == 0 => {
2839                             if let Some(field_names) = self.field_names.get(&did) {
2840                                 if field_names.iter().any(|&field_name| name == field_name) {
2841                                     return Some(AssocSuggestion::Field);
2842                                 }
2843                             }
2844                         }
2845                         _ => {}
2846                     }
2847                 }
2848             }
2849         }
2850
2851         // Look for associated items in the current trait.
2852         if let Some((trait_did, _)) = self.current_trait_ref {
2853             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2854                 if filter_fn(def) {
2855                     return Some(if has_self {
2856                         AssocSuggestion::MethodWithSelf
2857                     } else {
2858                         AssocSuggestion::AssocItem
2859                     });
2860                 }
2861             }
2862         }
2863
2864         None
2865     }
2866
2867     fn lookup_typo_candidate<FilterFn>(&mut self,
2868                                        path: &[Ident],
2869                                        ns: Namespace,
2870                                        filter_fn: FilterFn,
2871                                        span: Span)
2872                                        -> Option<Symbol>
2873         where FilterFn: Fn(Def) -> bool
2874     {
2875         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2876             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2877                 if let Some(binding) = resolution.borrow().binding {
2878                     if filter_fn(binding.def()) {
2879                         names.push(ident.name);
2880                     }
2881                 }
2882             }
2883         };
2884
2885         let mut names = Vec::new();
2886         if path.len() == 1 {
2887             // Search in lexical scope.
2888             // Walk backwards up the ribs in scope and collect candidates.
2889             for rib in self.ribs[ns].iter().rev() {
2890                 // Locals and type parameters
2891                 for (ident, def) in &rib.bindings {
2892                     if filter_fn(*def) {
2893                         names.push(ident.name);
2894                     }
2895                 }
2896                 // Items in scope
2897                 if let ModuleRibKind(module) = rib.kind {
2898                     // Items from this module
2899                     add_module_candidates(module, &mut names);
2900
2901                     if let ModuleKind::Block(..) = module.kind {
2902                         // We can see through blocks
2903                     } else {
2904                         // Items from the prelude
2905                         if let Some(prelude) = self.prelude {
2906                             if !module.no_implicit_prelude {
2907                                 add_module_candidates(prelude, &mut names);
2908                             }
2909                         }
2910                         break;
2911                     }
2912                 }
2913             }
2914             // Add primitive types to the mix
2915             if filter_fn(Def::PrimTy(TyBool)) {
2916                 for (name, _) in &self.primitive_type_table.primitive_types {
2917                     names.push(*name);
2918                 }
2919             }
2920         } else {
2921             // Search in module.
2922             let mod_path = &path[..path.len() - 1];
2923             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS),
2924                                                                   false, span) {
2925                 add_module_candidates(module, &mut names);
2926             }
2927         }
2928
2929         let name = path[path.len() - 1].name;
2930         // Make sure error reporting is deterministic.
2931         names.sort_by_key(|name| name.as_str());
2932         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2933             Some(found) if found != name => Some(found),
2934             _ => None,
2935         }
2936     }
2937
2938     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2939         where F: FnOnce(&mut Resolver)
2940     {
2941         if let Some(label) = label {
2942             let def = Def::Label(id);
2943             self.with_label_rib(|this| {
2944                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2945                 f(this);
2946             });
2947         } else {
2948             f(self);
2949         }
2950     }
2951
2952     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2953         self.with_resolved_label(label, id, |this| this.visit_block(block));
2954     }
2955
2956     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2957         // First, record candidate traits for this expression if it could
2958         // result in the invocation of a method call.
2959
2960         self.record_candidate_traits_for_expr_if_necessary(expr);
2961
2962         // Next, resolve the node.
2963         match expr.node {
2964             ExprKind::Path(ref qself, ref path) => {
2965                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2966                 visit::walk_expr(self, expr);
2967             }
2968
2969             ExprKind::Struct(ref path, ..) => {
2970                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2971                 visit::walk_expr(self, expr);
2972             }
2973
2974             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2975                 match self.search_label(label.node) {
2976                     None => {
2977                         self.record_def(expr.id, err_path_resolution());
2978                         resolve_error(self,
2979                                       label.span,
2980                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2981                     }
2982                     Some(def @ Def::Label(_)) => {
2983                         // Since this def is a label, it is never read.
2984                         self.record_def(expr.id, PathResolution::new(def));
2985                     }
2986                     Some(_) => {
2987                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2988                     }
2989                 }
2990
2991                 // visit `break` argument if any
2992                 visit::walk_expr(self, expr);
2993             }
2994
2995             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2996                 self.visit_expr(subexpression);
2997
2998                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2999                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
3000                 self.visit_block(if_block);
3001                 self.ribs[ValueNS].pop();
3002
3003                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
3004             }
3005
3006             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3007
3008             ExprKind::While(ref subexpression, ref block, label) => {
3009                 self.with_resolved_label(label, expr.id, |this| {
3010                     this.visit_expr(subexpression);
3011                     this.visit_block(block);
3012                 });
3013             }
3014
3015             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
3016                 self.with_resolved_label(label, expr.id, |this| {
3017                     this.visit_expr(subexpression);
3018                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
3019                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
3020                     this.visit_block(block);
3021                     this.ribs[ValueNS].pop();
3022                 });
3023             }
3024
3025             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
3026                 self.visit_expr(subexpression);
3027                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3028                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
3029
3030                 self.resolve_labeled_block(label, expr.id, block);
3031
3032                 self.ribs[ValueNS].pop();
3033             }
3034
3035             // Equivalent to `visit::walk_expr` + passing some context to children.
3036             ExprKind::Field(ref subexpression, _) => {
3037                 self.resolve_expr(subexpression, Some(expr));
3038             }
3039             ExprKind::MethodCall(_, ref types, ref arguments) => {
3040                 let mut arguments = arguments.iter();
3041                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3042                 for argument in arguments {
3043                     self.resolve_expr(argument, None);
3044                 }
3045                 for ty in types.iter() {
3046                     self.visit_ty(ty);
3047                 }
3048             }
3049
3050             ExprKind::Repeat(ref element, ref count) => {
3051                 self.visit_expr(element);
3052                 self.with_constant_rib(|this| {
3053                     this.visit_expr(count);
3054                 });
3055             }
3056             ExprKind::Call(ref callee, ref arguments) => {
3057                 self.resolve_expr(callee, Some(expr));
3058                 for argument in arguments {
3059                     self.resolve_expr(argument, None);
3060                 }
3061             }
3062
3063             _ => {
3064                 visit::walk_expr(self, expr);
3065             }
3066         }
3067     }
3068
3069     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3070         match expr.node {
3071             ExprKind::Field(_, name) => {
3072                 // FIXME(#6890): Even though you can't treat a method like a
3073                 // field, we need to add any trait methods we find that match
3074                 // the field name so that we can do some nice error reporting
3075                 // later on in typeck.
3076                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3077                 self.trait_map.insert(expr.id, traits);
3078             }
3079             ExprKind::MethodCall(name, ..) => {
3080                 debug!("(recording candidate traits for expr) recording traits for {}",
3081                        expr.id);
3082                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3083                 self.trait_map.insert(expr.id, traits);
3084             }
3085             _ => {
3086                 // Nothing to do.
3087             }
3088         }
3089     }
3090
3091     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3092         debug!("(getting traits containing item) looking for '{}'", name);
3093
3094         let mut found_traits = Vec::new();
3095         // Look for the current trait.
3096         if let Some((trait_def_id, _)) = self.current_trait_ref {
3097             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3098                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3099             }
3100         }
3101
3102         let mut search_module = self.current_module;
3103         loop {
3104             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3105             match search_module.kind {
3106                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3107                 _ => break,
3108             }
3109         }
3110
3111         if let Some(prelude) = self.prelude {
3112             if !search_module.no_implicit_prelude {
3113                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3114             }
3115         }
3116
3117         found_traits
3118     }
3119
3120     fn get_traits_in_module_containing_item(&mut self,
3121                                             name: Name,
3122                                             ns: Namespace,
3123                                             module: Module,
3124                                             found_traits: &mut Vec<TraitCandidate>) {
3125         let mut traits = module.traits.borrow_mut();
3126         if traits.is_none() {
3127             let mut collected_traits = Vec::new();
3128             module.for_each_child(|name, ns, binding| {
3129                 if ns != TypeNS { return }
3130                 if let Def::Trait(_) = binding.def() {
3131                     collected_traits.push((name, binding));
3132                 }
3133             });
3134             *traits = Some(collected_traits.into_boxed_slice());
3135         }
3136
3137         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3138             let trait_def_id = binding.def().def_id();
3139             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3140                 let import_id = match binding.kind {
3141                     NameBindingKind::Import { directive, .. } => {
3142                         self.maybe_unused_trait_imports.insert(directive.id);
3143                         self.add_to_glob_map(directive.id, trait_name);
3144                         Some(directive.id)
3145                     }
3146                     _ => None,
3147                 };
3148                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3149             }
3150         }
3151     }
3152
3153     /// When name resolution fails, this method can be used to look up candidate
3154     /// entities with the expected name. It allows filtering them using the
3155     /// supplied predicate (which should be used to only accept the types of
3156     /// definitions expected e.g. traits). The lookup spans across all crates.
3157     ///
3158     /// NOTE: The method does not look into imports, but this is not a problem,
3159     /// since we report the definitions (thus, the de-aliased imports).
3160     fn lookup_import_candidates<FilterFn>(&mut self,
3161                                           lookup_name: Name,
3162                                           namespace: Namespace,
3163                                           filter_fn: FilterFn)
3164                                           -> Vec<ImportSuggestion>
3165         where FilterFn: Fn(Def) -> bool
3166     {
3167         let mut candidates = Vec::new();
3168         let mut worklist = Vec::new();
3169         let mut seen_modules = FxHashSet();
3170         worklist.push((self.graph_root, Vec::new(), false));
3171
3172         while let Some((in_module,
3173                         path_segments,
3174                         in_module_is_extern)) = worklist.pop() {
3175             self.populate_module_if_necessary(in_module);
3176
3177             in_module.for_each_child(|ident, ns, name_binding| {
3178
3179                 // avoid imports entirely
3180                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3181                 // avoid non-importable candidates as well
3182                 if !name_binding.is_importable() { return; }
3183
3184                 // collect results based on the filter function
3185                 if ident.name == lookup_name && ns == namespace {
3186                     if filter_fn(name_binding.def()) {
3187                         // create the path
3188                         let mut segms = path_segments.clone();
3189                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3190                         let path = Path {
3191                             span: name_binding.span,
3192                             segments: segms,
3193                         };
3194                         // the entity is accessible in the following cases:
3195                         // 1. if it's defined in the same crate, it's always
3196                         // accessible (since private entities can be made public)
3197                         // 2. if it's defined in another crate, it's accessible
3198                         // only if both the module is public and the entity is
3199                         // declared as public (due to pruning, we don't explore
3200                         // outside crate private modules => no need to check this)
3201                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3202                             candidates.push(ImportSuggestion { path: path });
3203                         }
3204                     }
3205                 }
3206
3207                 // collect submodules to explore
3208                 if let Some(module) = name_binding.module() {
3209                     // form the path
3210                     let mut path_segments = path_segments.clone();
3211                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3212
3213                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3214                         // add the module to the lookup
3215                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3216                         if seen_modules.insert(module.def_id().unwrap()) {
3217                             worklist.push((module, path_segments, is_extern));
3218                         }
3219                     }
3220                 }
3221             })
3222         }
3223
3224         candidates
3225     }
3226
3227     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3228         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3229         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3230             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3231         }
3232     }
3233
3234     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3235         match *vis {
3236             ast::Visibility::Public => ty::Visibility::Public,
3237             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3238             ast::Visibility::Inherited => {
3239                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3240             }
3241             ast::Visibility::Restricted { ref path, id } => {
3242                 let def = self.smart_resolve_path(id, None, path,
3243                                                   PathSource::Visibility).base_def();
3244                 if def == Def::Err {
3245                     ty::Visibility::Public
3246                 } else {
3247                     let vis = ty::Visibility::Restricted(def.def_id());
3248                     if self.is_accessible(vis) {
3249                         vis
3250                     } else {
3251                         self.session.span_err(path.span, "visibilities can only be restricted \
3252                                                           to ancestor modules");
3253                         ty::Visibility::Public
3254                     }
3255                 }
3256             }
3257         }
3258     }
3259
3260     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3261         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3262     }
3263
3264     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3265         vis.is_accessible_from(module.normal_ancestor_id, self)
3266     }
3267
3268     fn report_errors(&mut self) {
3269         self.report_shadowing_errors();
3270         let mut reported_spans = FxHashSet();
3271
3272         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3273             if !reported_spans.insert(span) { continue }
3274             let participle = |binding: &NameBinding| {
3275                 if binding.is_import() { "imported" } else { "defined" }
3276             };
3277             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3278             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3279             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3280                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3281             } else if let Def::Macro(..) = b1.def() {
3282                 format!("macro-expanded {} do not shadow",
3283                         if b1.is_import() { "macro imports" } else { "macros" })
3284             } else {
3285                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3286                         if b1.is_import() { "imports" } else { "items" })
3287             };
3288             if legacy {
3289                 let id = match b2.kind {
3290                     NameBindingKind::Import { directive, .. } => directive.id,
3291                     _ => unreachable!(),
3292                 };
3293                 let mut span = MultiSpan::from_span(span);
3294                 span.push_span_label(b1.span, msg1);
3295                 span.push_span_label(b2.span, msg2);
3296                 let msg = format!("`{}` is ambiguous", name);
3297                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3298             } else {
3299                 let mut err =
3300                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3301                 err.span_note(b1.span, &msg1);
3302                 match b2.def() {
3303                     Def::Macro(..) if b2.span == DUMMY_SP =>
3304                         err.note(&format!("`{}` is also a builtin macro", name)),
3305                     _ => err.span_note(b2.span, &msg2),
3306                 };
3307                 err.note(&note).emit();
3308             }
3309         }
3310
3311         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3312             if !reported_spans.insert(span) { continue }
3313             if binding.is_extern_crate() {
3314                 // Warn when using an inaccessible extern crate.
3315                 let node_id = match binding.kind {
3316                     NameBindingKind::Import { directive, .. } => directive.id,
3317                     _ => unreachable!(),
3318                 };
3319                 let msg = format!("extern crate `{}` is private", name);
3320                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3321             } else {
3322                 let def = binding.def();
3323                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3324             }
3325         }
3326     }
3327
3328     fn report_shadowing_errors(&mut self) {
3329         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3330             self.resolve_legacy_scope(scope, name, true);
3331         }
3332
3333         let mut reported_errors = FxHashSet();
3334         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3335             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3336                reported_errors.insert((binding.name, binding.span)) {
3337                 let msg = format!("`{}` is already in scope", binding.name);
3338                 self.session.struct_span_err(binding.span, &msg)
3339                     .note("macro-expanded `macro_rules!`s may not shadow \
3340                            existing macros (see RFC 1560)")
3341                     .emit();
3342             }
3343         }
3344     }
3345
3346     fn report_conflict(&mut self,
3347                        parent: Module,
3348                        ident: Ident,
3349                        ns: Namespace,
3350                        binding: &NameBinding,
3351                        old_binding: &NameBinding) {
3352         // Error on the second of two conflicting names
3353         if old_binding.span.lo > binding.span.lo {
3354             return self.report_conflict(parent, ident, ns, old_binding, binding);
3355         }
3356
3357         let container = match parent.kind {
3358             ModuleKind::Def(Def::Mod(_), _) => "module",
3359             ModuleKind::Def(Def::Trait(_), _) => "trait",
3360             ModuleKind::Block(..) => "block",
3361             _ => "enum",
3362         };
3363
3364         let (participle, noun) = match old_binding.is_import() {
3365             true => ("imported", "import"),
3366             false => ("defined", "definition"),
3367         };
3368
3369         let (name, span) = (ident.name, binding.span);
3370
3371         if let Some(s) = self.name_already_seen.get(&name) {
3372             if s == &span {
3373                 return;
3374             }
3375         }
3376
3377         let msg = {
3378             let kind = match (ns, old_binding.module()) {
3379                 (ValueNS, _) => "a value",
3380                 (MacroNS, _) => "a macro",
3381                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3382                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3383                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3384                 (TypeNS, _) => "a type",
3385             };
3386             format!("{} named `{}` has already been {} in this {}",
3387                     kind, name, participle, container)
3388         };
3389
3390         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3391             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3392             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3393                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3394                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3395             },
3396             _ => match (old_binding.is_import(), binding.is_import()) {
3397                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3398                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3399                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3400             },
3401         };
3402
3403         err.span_label(span, format!("`{}` already {}", name, participle));
3404         if old_binding.span != syntax_pos::DUMMY_SP {
3405             err.span_label(old_binding.span, format!("previous {} of `{}` here", noun, name));
3406         }
3407         err.emit();
3408         self.name_already_seen.insert(name, span);
3409     }
3410
3411     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3412         let (id, span) = (directive.id, directive.span);
3413         let msg = "`self` no longer imports values".to_string();
3414         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3415     }
3416
3417     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3418         if self.proc_macro_enabled { return; }
3419
3420         for attr in attrs {
3421             if attr.path.segments.len() > 1 {
3422                 continue
3423             }
3424             let ident = attr.path.segments[0].identifier;
3425             let result = self.resolve_lexical_macro_path_segment(ident,
3426                                                                  MacroNS,
3427                                                                  false,
3428                                                                  attr.path.span);
3429             if let Ok(binding) = result {
3430                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3431                     attr::mark_known(attr);
3432
3433                     let msg = "attribute procedural macros are experimental";
3434                     let feature = "proc_macro";
3435
3436                     feature_err(&self.session.parse_sess, feature,
3437                                 attr.span, GateIssue::Language, msg)
3438                         .span_note(binding.span(), "procedural macro imported here")
3439                         .emit();
3440                 }
3441             }
3442         }
3443     }
3444 }
3445
3446 fn is_struct_like(def: Def) -> bool {
3447     match def {
3448         Def::VariantCtor(_, CtorKind::Fictive) => true,
3449         _ => PathSource::Struct.is_expected(def),
3450     }
3451 }
3452
3453 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3454     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3455 }
3456
3457 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3458     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3459 }
3460
3461 fn names_to_string(idents: &[Ident]) -> String {
3462     let mut result = String::new();
3463     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3464         if i > 0 {
3465             result.push_str("::");
3466         }
3467         result.push_str(&ident.name.as_str());
3468     }
3469     result
3470 }
3471
3472 fn path_names_to_string(path: &Path) -> String {
3473     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3474 }
3475
3476 /// Get the path for an enum and the variant from an `ImportSuggestion` for an enum variant.
3477 fn import_candidate_to_paths(suggestion: &ImportSuggestion) -> (Span, String, String) {
3478     let variant_path = &suggestion.path;
3479     let variant_path_string = path_names_to_string(variant_path);
3480
3481     let path_len = suggestion.path.segments.len();
3482     let enum_path = ast::Path {
3483         span: suggestion.path.span,
3484         segments: suggestion.path.segments[0..path_len - 1].to_vec(),
3485     };
3486     let enum_path_string = path_names_to_string(&enum_path);
3487
3488     (suggestion.path.span, variant_path_string, enum_path_string)
3489 }
3490
3491
3492 /// When an entity with a given name is not available in scope, we search for
3493 /// entities with that name in all crates. This method allows outputting the
3494 /// results of this search in a programmer-friendly way
3495 fn show_candidates(err: &mut DiagnosticBuilder,
3496                    span: Span,
3497                    candidates: &[ImportSuggestion],
3498                    better: bool) {
3499
3500     // we want consistent results across executions, but candidates are produced
3501     // by iterating through a hash map, so make sure they are ordered:
3502     let mut path_strings: Vec<_> =
3503         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3504     path_strings.sort();
3505
3506     let better = if better { "better " } else { "" };
3507     let msg_diff = match path_strings.len() {
3508         1 => " is found in another module, you can import it",
3509         _ => "s are found in other modules, you can import them",
3510     };
3511     let msg = format!("possible {}candidate{} into scope", better, msg_diff);
3512
3513     for candidate in &mut path_strings {
3514         *candidate = format!("use {};\n", candidate);
3515     }
3516
3517     err.span_suggestions(span, &msg, path_strings);
3518 }
3519
3520 /// A somewhat inefficient routine to obtain the name of a module.
3521 fn module_to_string(module: Module) -> String {
3522     let mut names = Vec::new();
3523
3524     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3525         if let ModuleKind::Def(_, name) = module.kind {
3526             if let Some(parent) = module.parent {
3527                 names.push(Ident::with_empty_ctxt(name));
3528                 collect_mod(names, parent);
3529             }
3530         } else {
3531             // danger, shouldn't be ident?
3532             names.push(Ident::from_str("<opaque>"));
3533             collect_mod(names, module.parent.unwrap());
3534         }
3535     }
3536     collect_mod(&mut names, module);
3537
3538     if names.is_empty() {
3539         return "???".to_string();
3540     }
3541     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3542 }
3543
3544 fn err_path_resolution() -> PathResolution {
3545     PathResolution::new(Def::Err)
3546 }
3547
3548 #[derive(PartialEq,Copy, Clone)]
3549 pub enum MakeGlobMap {
3550     Yes,
3551     No,
3552 }
3553
3554 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }