src/librustc_resolve/lib.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![crate_name = "rustc_resolve"]
  12 #![unstable(feature = "rustc_private", issue = "27812")]
  13 #![crate_type = "dylib"]
  14 #![crate_type = "rlib"]
  15 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  16       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  17       html_root_url = "https://doc.rust-lang.org/nightly/")]
  18 #![deny(warnings)]
  19
  20 #![feature(associated_consts)]
  21 #![feature(rustc_diagnostic_macros)]
  22 #![feature(rustc_private)]
  23 #![feature(staged_api)]
  24
  25 #[macro_use]
  26 extern crate log;
  27 #[macro_use]
  28 extern crate syntax;
  29 extern crate syntax_pos;
  30 extern crate rustc_errors as errors;
  31 extern crate arena;
  32 #[macro_use]
  33 extern crate rustc;
  34
  35 use self::Namespace::*;
  36 use self::TypeParameters::*;
  37 use self::RibKind::*;
  38
  39 use rustc::hir::map::{Definitions, DefCollector};
  40 use rustc::hir::{self, PrimTy, TyBool, TyChar, TyFloat, TyInt, TyUint, TyStr};
  41 use rustc::middle::cstore::CrateLoader;
  42 use rustc::session::Session;
  43 use rustc::lint;
  44 use rustc::hir::def::*;
  45 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  46 use rustc::ty;
  47 use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
  48 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
  49
  50 use syntax::ext::hygiene::{Mark, SyntaxContext};
  51 use syntax::ast::{self, Name, NodeId, Ident, SpannedIdent, FloatTy, IntTy, UintTy};
  52 use syntax::ext::base::SyntaxExtension;
  53 use syntax::ext::base::Determinacy::{Determined, Undetermined};
  54 use syntax::ext::base::MacroKind;
  55 use syntax::symbol::{Symbol, keywords};
  56 use syntax::util::lev_distance::find_best_match_for_name;
  57
  58 use syntax::visit::{self, FnKind, Visitor};
  59 use syntax::attr;
  60 use syntax::ast::{Arm, BindingMode, Block, Crate, Expr, ExprKind};
  61 use syntax::ast::{FnDecl, ForeignItem, ForeignItemKind, Generics};
  62 use syntax::ast::{Item, ItemKind, ImplItem, ImplItemKind};
  63 use syntax::ast::{Local, Mutability, Pat, PatKind, Path};
  64 use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
  65 use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
  66
  67 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  68 use errors::DiagnosticBuilder;
  69
  70 use std::cell::{Cell, RefCell};
  71 use std::cmp;
  72 use std::collections::BTreeSet;
  73 use std::fmt;
  74 use std::mem::replace;
  75 use std::rc::Rc;
  76
  77 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
  78 use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
  79
  80 // NB: This module needs to be declared first so diagnostics are
  81 // registered before they are used.
  82 mod diagnostics;
  83
  84 mod macros;
  85 mod check_unused;
  86 mod build_reduced_graph;
  87 mod resolve_imports;
  88
  89 /// A free importable items suggested in case of resolution failure.
  90 struct ImportSuggestion {
  91     path: Path,
  92 }
  93
  94 /// A field or associated item from self type suggested in case of resolution failure.
  95 enum AssocSuggestion {
  96     Field,
  97     MethodWithSelf,
  98     AssocItem,
  99 }
 100
 101 #[derive(Eq)]
 102 struct BindingError {
 103     name: Name,
 104     origin: BTreeSet<Span>,
 105     target: BTreeSet<Span>,
 106 }
 107
 108 impl PartialOrd for BindingError {
 109     fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
 110         Some(self.cmp(other))
 111     }
 112 }
 113
 114 impl PartialEq for BindingError {
 115     fn eq(&self, other: &BindingError) -> bool {
 116         self.name == other.name
 117     }
 118 }
 119
 120 impl Ord for BindingError {
 121     fn cmp(&self, other: &BindingError) -> cmp::Ordering {
 122         self.name.cmp(&other.name)
 123     }
 124 }
 125
 126 enum ResolutionError<'a> {
 127     /// error E0401: can't use type parameters from outer function
 128     TypeParametersFromOuterFunction,
 129     /// error E0402: cannot use an outer type parameter in this context
 130     OuterTypeParameterContext,
 131     /// error E0403: the name is already used for a type parameter in this type parameter list
 132     NameAlreadyUsedInTypeParameterList(Name, &'a Span),
 133     /// error E0407: method is not a member of trait
 134     MethodNotMemberOfTrait(Name, &'a str),
 135     /// error E0437: type is not a member of trait
 136     TypeNotMemberOfTrait(Name, &'a str),
 137     /// error E0438: const is not a member of trait
 138     ConstNotMemberOfTrait(Name, &'a str),
 139     /// error E0408: variable `{}` is not bound in all patterns
 140     VariableNotBoundInPattern(&'a BindingError),
 141     /// error E0409: variable `{}` is bound in inconsistent ways within the same match arm
 142     VariableBoundWithDifferentMode(Name, Span),
 143     /// error E0415: identifier is bound more than once in this parameter list
 144     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 145     /// error E0416: identifier is bound more than once in the same pattern
 146     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 147     /// error E0426: use of undeclared label
 148     UndeclaredLabel(&'a str),
 149     /// error E0429: `self` imports are only allowed within a { } list
 150     SelfImportsOnlyAllowedWithin,
 151     /// error E0430: `self` import can only appear once in the list
 152     SelfImportCanOnlyAppearOnceInTheList,
 153     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 154     SelfImportOnlyInImportListWithNonEmptyPrefix,
 155     /// error E0432: unresolved import
 156     UnresolvedImport(Option<(&'a str, &'a str)>),
 157     /// error E0433: failed to resolve
 158     FailedToResolve(&'a str),
 159     /// error E0434: can't capture dynamic environment in a fn item
 160     CannotCaptureDynamicEnvironmentInFnItem,
 161     /// error E0435: attempt to use a non-constant value in a constant
 162     AttemptToUseNonConstantValueInConstant,
 163     /// error E0530: X bindings cannot shadow Ys
 164     BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
 165     /// error E0128: type parameters with a default cannot use forward declared identifiers
 166     ForwardDeclaredTyParam,
 167 }
 168
 169 fn resolve_error<'sess, 'a>(resolver: &'sess Resolver,
 170                             span: Span,
 171                             resolution_error: ResolutionError<'a>) {
 172     resolve_struct_error(resolver, span, resolution_error).emit();
 173 }
 174
 175 fn resolve_struct_error<'sess, 'a>(resolver: &'sess Resolver,
 176                                    span: Span,
 177                                    resolution_error: ResolutionError<'a>)
 178                                    -> DiagnosticBuilder<'sess> {
 179     match resolution_error {
 180         ResolutionError::TypeParametersFromOuterFunction => {
 181             let mut err = struct_span_err!(resolver.session,
 182                                            span,
 183                                            E0401,
 184                                            "can't use type parameters from outer function; \
 185                                            try using a local type parameter instead");
 186             err.span_label(span, &format!("use of type variable from outer function"));
 187             err
 188         }
 189         ResolutionError::OuterTypeParameterContext => {
 190             struct_span_err!(resolver.session,
 191                              span,
 192                              E0402,
 193                              "cannot use an outer type parameter in this context")
 194         }
 195         ResolutionError::NameAlreadyUsedInTypeParameterList(name, first_use_span) => {
 196              let mut err = struct_span_err!(resolver.session,
 197                                             span,
 198                                             E0403,
 199                                             "the name `{}` is already used for a type parameter \
 200                                             in this type parameter list",
 201                                             name);
 202              err.span_label(span, &format!("already used"));
 203              err.span_label(first_use_span.clone(), &format!("first use of `{}`", name));
 204              err
 205         }
 206         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 207             let mut err = struct_span_err!(resolver.session,
 208                                            span,
 209                                            E0407,
 210                                            "method `{}` is not a member of trait `{}`",
 211                                            method,
 212                                            trait_);
 213             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 214             err
 215         }
 216         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 217             let mut err = struct_span_err!(resolver.session,
 218                              span,
 219                              E0437,
 220                              "type `{}` is not a member of trait `{}`",
 221                              type_,
 222                              trait_);
 223             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 224             err
 225         }
 226         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 227             let mut err = struct_span_err!(resolver.session,
 228                              span,
 229                              E0438,
 230                              "const `{}` is not a member of trait `{}`",
 231                              const_,
 232                              trait_);
 233             err.span_label(span, &format!("not a member of trait `{}`", trait_));
 234             err
 235         }
 236         ResolutionError::VariableNotBoundInPattern(binding_error) => {
 237             let target_sp = binding_error.target.iter().map(|x| *x).collect::<Vec<_>>();
 238             let msp = MultiSpan::from_spans(target_sp.clone());
 239             let msg = format!("variable `{}` is not bound in all patterns", binding_error.name);
 240             let mut err = resolver.session.struct_span_err_with_code(msp, &msg, "E0408");
 241             for sp in target_sp {
 242                 err.span_label(sp, &format!("pattern doesn't bind `{}`", binding_error.name));
 243             }
 244             let origin_sp = binding_error.origin.iter().map(|x| *x).collect::<Vec<_>>();
 245             for sp in origin_sp {
 246                 err.span_label(sp, &"variable not in all patterns");
 247             }
 248             err
 249         }
 250         ResolutionError::VariableBoundWithDifferentMode(variable_name,
 251                                                         first_binding_span) => {
 252             let mut err = struct_span_err!(resolver.session,
 253                              span,
 254                              E0409,
 255                              "variable `{}` is bound in inconsistent \
 256                              ways within the same match arm",
 257                              variable_name);
 258             err.span_label(span, &format!("bound in different ways"));
 259             err.span_label(first_binding_span, &format!("first binding"));
 260             err
 261         }
 262         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 263             let mut err = struct_span_err!(resolver.session,
 264                              span,
 265                              E0415,
 266                              "identifier `{}` is bound more than once in this parameter list",
 267                              identifier);
 268             err.span_label(span, &format!("used as parameter more than once"));
 269             err
 270         }
 271         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 272             let mut err = struct_span_err!(resolver.session,
 273                              span,
 274                              E0416,
 275                              "identifier `{}` is bound more than once in the same pattern",
 276                              identifier);
 277             err.span_label(span, &format!("used in a pattern more than once"));
 278             err
 279         }
 280         ResolutionError::UndeclaredLabel(name) => {
 281             let mut err = struct_span_err!(resolver.session,
 282                                            span,
 283                                            E0426,
 284                                            "use of undeclared label `{}`",
 285                                            name);
 286             err.span_label(span, &format!("undeclared label `{}`",&name));
 287             err
 288         }
 289         ResolutionError::SelfImportsOnlyAllowedWithin => {
 290             struct_span_err!(resolver.session,
 291                              span,
 292                              E0429,
 293                              "{}",
 294                              "`self` imports are only allowed within a { } list")
 295         }
 296         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 297             struct_span_err!(resolver.session,
 298                              span,
 299                              E0430,
 300                              "`self` import can only appear once in the list")
 301         }
 302         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 303             struct_span_err!(resolver.session,
 304                              span,
 305                              E0431,
 306                              "`self` import can only appear in an import list with a \
 307                               non-empty prefix")
 308         }
 309         ResolutionError::UnresolvedImport(name) => {
 310             let msg = match name {
 311                 Some((n, _)) => format!("unresolved import `{}`", n),
 312                 None => "unresolved import".to_owned(),
 313             };
 314             let mut err = struct_span_err!(resolver.session, span, E0432, "{}", msg);
 315             if let Some((_, p)) = name {
 316                 err.span_label(span, &p);
 317             }
 318             err
 319         }
 320         ResolutionError::FailedToResolve(msg) => {
 321             let mut err = struct_span_err!(resolver.session, span, E0433,
 322                                            "failed to resolve. {}", msg);
 323             err.span_label(span, &msg);
 324             err
 325         }
 326         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 327             struct_span_err!(resolver.session,
 328                              span,
 329                              E0434,
 330                              "{}",
 331                              "can't capture dynamic environment in a fn item; use the || { ... } \
 332                               closure form instead")
 333         }
 334         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 335             let mut err = struct_span_err!(resolver.session,
 336                              span,
 337                              E0435,
 338                              "attempt to use a non-constant value in a constant");
 339             err.span_label(span, &format!("non-constant used with constant"));
 340             err
 341         }
 342         ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
 343             let shadows_what = PathResolution::new(binding.def()).kind_name();
 344             let mut err = struct_span_err!(resolver.session,
 345                                            span,
 346                                            E0530,
 347                                            "{}s cannot shadow {}s", what_binding, shadows_what);
 348             err.span_label(span, &format!("cannot be named the same as a {}", shadows_what));
 349             let participle = if binding.is_import() { "imported" } else { "defined" };
 350             let msg = &format!("a {} `{}` is {} here", shadows_what, name, participle);
 351             err.span_label(binding.span, msg);
 352             err
 353         }
 354         ResolutionError::ForwardDeclaredTyParam => {
 355             let mut err = struct_span_err!(resolver.session, span, E0128,
 356                                            "type parameters with a default cannot use \
 357                                             forward declared identifiers");
 358             err.span_label(span, &format!("defaulted type parameters \
 359                                            cannot be forward declared"));
 360             err
 361         }
 362     }
 363 }
 364
 365 #[derive(Copy, Clone, Debug)]
 366 struct BindingInfo {
 367     span: Span,
 368     binding_mode: BindingMode,
 369 }
 370
 371 // Map from the name in a pattern to its binding mode.
 372 type BindingMap = FxHashMap<Ident, BindingInfo>;
 373
 374 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 375 enum PatternSource {
 376     Match,
 377     IfLet,
 378     WhileLet,
 379     Let,
 380     For,
 381     FnParam,
 382 }
 383
 384 impl PatternSource {
 385     fn is_refutable(self) -> bool {
 386         match self {
 387             PatternSource::Match | PatternSource::IfLet | PatternSource::WhileLet => true,
 388             PatternSource::Let | PatternSource::For | PatternSource::FnParam  => false,
 389         }
 390     }
 391     fn descr(self) -> &'static str {
 392         match self {
 393             PatternSource::Match => "match binding",
 394             PatternSource::IfLet => "if let binding",
 395             PatternSource::WhileLet => "while let binding",
 396             PatternSource::Let => "let binding",
 397             PatternSource::For => "for binding",
 398             PatternSource::FnParam => "function parameter",
 399         }
 400     }
 401 }
 402
 403 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 404 enum PathSource<'a> {
 405     // Type paths `Path`.
 406     Type,
 407     // Trait paths in bounds or impls.
 408     Trait,
 409     // Expression paths `path`, with optional parent context.
 410     Expr(Option<&'a Expr>),
 411     // Paths in path patterns `Path`.
 412     Pat,
 413     // Paths in struct expressions and patterns `Path { .. }`.
 414     Struct,
 415     // Paths in tuple struct patterns `Path(..)`.
 416     TupleStruct,
 417     // `m::A::B` in `<T as m::A>::B::C`.
 418     TraitItem(Namespace),
 419     // Path in `pub(path)`
 420     Visibility,
 421     // Path in `use a::b::{...};`
 422     ImportPrefix,
 423 }
 424
 425 impl<'a> PathSource<'a> {
 426     fn namespace(self) -> Namespace {
 427         match self {
 428             PathSource::Type | PathSource::Trait | PathSource::Struct |
 429             PathSource::Visibility | PathSource::ImportPrefix => TypeNS,
 430             PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
 431             PathSource::TraitItem(ns) => ns,
 432         }
 433     }
 434
 435     fn global_by_default(self) -> bool {
 436         match self {
 437             PathSource::Visibility | PathSource::ImportPrefix => true,
 438             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 439             PathSource::Struct | PathSource::TupleStruct |
 440             PathSource::Trait | PathSource::TraitItem(..) => false,
 441         }
 442     }
 443
 444     fn defer_to_typeck(self) -> bool {
 445         match self {
 446             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 447             PathSource::Struct | PathSource::TupleStruct => true,
 448             PathSource::Trait | PathSource::TraitItem(..) |
 449             PathSource::Visibility | PathSource::ImportPrefix => false,
 450         }
 451     }
 452
 453     fn descr_expected(self) -> &'static str {
 454         match self {
 455             PathSource::Type => "type",
 456             PathSource::Trait => "trait",
 457             PathSource::Pat => "unit struct/variant or constant",
 458             PathSource::Struct => "struct, variant or union type",
 459             PathSource::TupleStruct => "tuple struct/variant",
 460             PathSource::Visibility => "module",
 461             PathSource::ImportPrefix => "module or enum",
 462             PathSource::TraitItem(ns) => match ns {
 463                 TypeNS => "associated type",
 464                 ValueNS => "method or associated constant",
 465                 MacroNS => bug!("associated macro"),
 466             },
 467             PathSource::Expr(parent) => match parent.map(|p| &p.node) {
 468                 // "function" here means "anything callable" rather than `Def::Fn`,
 469                 // this is not precise but usually more helpful than just "value".
 470                 Some(&ExprKind::Call(..)) => "function",
 471                 _ => "value",
 472             },
 473         }
 474     }
 475
 476     fn is_expected(self, def: Def) -> bool {
 477         match self {
 478             PathSource::Type => match def {
 479                 Def::Struct(..) | Def::Union(..) | Def::Enum(..) |
 480                 Def::Trait(..) | Def::TyAlias(..) | Def::AssociatedTy(..) |
 481                 Def::PrimTy(..) | Def::TyParam(..) | Def::SelfTy(..) => true,
 482                 _ => false,
 483             },
 484             PathSource::Trait => match def {
 485                 Def::Trait(..) => true,
 486                 _ => false,
 487             },
 488             PathSource::Expr(..) => match def {
 489                 Def::StructCtor(_, CtorKind::Const) | Def::StructCtor(_, CtorKind::Fn) |
 490                 Def::VariantCtor(_, CtorKind::Const) | Def::VariantCtor(_, CtorKind::Fn) |
 491                 Def::Const(..) | Def::Static(..) | Def::Local(..) | Def::Upvar(..) |
 492                 Def::Fn(..) | Def::Method(..) | Def::AssociatedConst(..) => true,
 493                 _ => false,
 494             },
 495             PathSource::Pat => match def {
 496                 Def::StructCtor(_, CtorKind::Const) |
 497                 Def::VariantCtor(_, CtorKind::Const) |
 498                 Def::Const(..) | Def::AssociatedConst(..) => true,
 499                 _ => false,
 500             },
 501             PathSource::TupleStruct => match def {
 502                 Def::StructCtor(_, CtorKind::Fn) | Def::VariantCtor(_, CtorKind::Fn) => true,
 503                 _ => false,
 504             },
 505             PathSource::Struct => match def {
 506                 Def::Struct(..) | Def::Union(..) | Def::Variant(..) |
 507                 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => true,
 508                 _ => false,
 509             },
 510             PathSource::TraitItem(ns) => match def {
 511                 Def::AssociatedConst(..) | Def::Method(..) if ns == ValueNS => true,
 512                 Def::AssociatedTy(..) if ns == TypeNS => true,
 513                 _ => false,
 514             },
 515             PathSource::ImportPrefix => match def {
 516                 Def::Mod(..) | Def::Enum(..) => true,
 517                 _ => false,
 518             },
 519             PathSource::Visibility => match def {
 520                 Def::Mod(..) => true,
 521                 _ => false,
 522             },
 523         }
 524     }
 525
 526     fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
 527         __diagnostic_used!(E0404);
 528         __diagnostic_used!(E0405);
 529         __diagnostic_used!(E0412);
 530         __diagnostic_used!(E0422);
 531         __diagnostic_used!(E0423);
 532         __diagnostic_used!(E0425);
 533         __diagnostic_used!(E0531);
 534         __diagnostic_used!(E0532);
 535         __diagnostic_used!(E0573);
 536         __diagnostic_used!(E0574);
 537         __diagnostic_used!(E0575);
 538         __diagnostic_used!(E0576);
 539         __diagnostic_used!(E0577);
 540         __diagnostic_used!(E0578);
 541         match (self, has_unexpected_resolution) {
 542             (PathSource::Trait, true) => "E0404",
 543             (PathSource::Trait, false) => "E0405",
 544             (PathSource::Type, true) => "E0573",
 545             (PathSource::Type, false) => "E0412",
 546             (PathSource::Struct, true) => "E0574",
 547             (PathSource::Struct, false) => "E0422",
 548             (PathSource::Expr(..), true) => "E0423",
 549             (PathSource::Expr(..), false) => "E0425",
 550             (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
 551             (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
 552             (PathSource::TraitItem(..), true) => "E0575",
 553             (PathSource::TraitItem(..), false) => "E0576",
 554             (PathSource::Visibility, true) | (PathSource::ImportPrefix, true) => "E0577",
 555             (PathSource::Visibility, false) | (PathSource::ImportPrefix, false) => "E0578",
 556         }
 557     }
 558 }
 559
 560 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 561 pub enum Namespace {
 562     TypeNS,
 563     ValueNS,
 564     MacroNS,
 565 }
 566
 567 #[derive(Clone, Default, Debug)]
 568 pub struct PerNS<T> {
 569     value_ns: T,
 570     type_ns: T,
 571     macro_ns: Option<T>,
 572 }
 573
 574 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
 575     type Output = T;
 576     fn index(&self, ns: Namespace) -> &T {
 577         match ns {
 578             ValueNS => &self.value_ns,
 579             TypeNS => &self.type_ns,
 580             MacroNS => self.macro_ns.as_ref().unwrap(),
 581         }
 582     }
 583 }
 584
 585 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
 586     fn index_mut(&mut self, ns: Namespace) -> &mut T {
 587         match ns {
 588             ValueNS => &mut self.value_ns,
 589             TypeNS => &mut self.type_ns,
 590             MacroNS => self.macro_ns.as_mut().unwrap(),
 591         }
 592     }
 593 }
 594
 595 impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
 596     fn visit_item(&mut self, item: &'tcx Item) {
 597         self.resolve_item(item);
 598     }
 599     fn visit_arm(&mut self, arm: &'tcx Arm) {
 600         self.resolve_arm(arm);
 601     }
 602     fn visit_block(&mut self, block: &'tcx Block) {
 603         self.resolve_block(block);
 604     }
 605     fn visit_expr(&mut self, expr: &'tcx Expr) {
 606         self.resolve_expr(expr, None);
 607     }
 608     fn visit_local(&mut self, local: &'tcx Local) {
 609         self.resolve_local(local);
 610     }
 611     fn visit_ty(&mut self, ty: &'tcx Ty) {
 612         if let TyKind::Path(ref qself, ref path) = ty.node {
 613             self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
 614         } else if let TyKind::ImplicitSelf = ty.node {
 615             let self_ty = keywords::SelfType.ident();
 616             let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, Some(ty.span))
 617                           .map_or(Def::Err, |d| d.def());
 618             self.record_def(ty.id, PathResolution::new(def));
 619         } else if let TyKind::Array(ref element, ref length) = ty.node {
 620             self.visit_ty(element);
 621             self.with_constant_rib(|this| {
 622                 this.visit_expr(length);
 623             });
 624             return;
 625         }
 626         visit::walk_ty(self, ty);
 627     }
 628     fn visit_poly_trait_ref(&mut self,
 629                             tref: &'tcx ast::PolyTraitRef,
 630                             m: &'tcx ast::TraitBoundModifier) {
 631         self.smart_resolve_path(tref.trait_ref.ref_id, None,
 632                                 &tref.trait_ref.path, PathSource::Trait);
 633         visit::walk_poly_trait_ref(self, tref, m);
 634     }
 635     fn visit_variant(&mut self,
 636                      variant: &'tcx ast::Variant,
 637                      generics: &'tcx Generics,
 638                      item_id: ast::NodeId) {
 639         if let Some(ref dis_expr) = variant.node.disr_expr {
 640             // resolve the discriminator expr as a constant
 641             self.with_constant_rib(|this| {
 642                 this.visit_expr(dis_expr);
 643             });
 644         }
 645
 646         // `visit::walk_variant` without the discriminant expression.
 647         self.visit_variant_data(&variant.node.data,
 648                                 variant.node.name,
 649                                 generics,
 650                                 item_id,
 651                                 variant.span);
 652     }
 653     fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
 654         let type_parameters = match foreign_item.node {
 655             ForeignItemKind::Fn(_, ref generics) => {
 656                 HasTypeParameters(generics, ItemRibKind)
 657             }
 658             ForeignItemKind::Static(..) => NoTypeParameters,
 659         };
 660         self.with_type_parameter_rib(type_parameters, |this| {
 661             visit::walk_foreign_item(this, foreign_item);
 662         });
 663     }
 664     fn visit_fn(&mut self,
 665                 function_kind: FnKind<'tcx>,
 666                 declaration: &'tcx FnDecl,
 667                 _: Span,
 668                 node_id: NodeId) {
 669         let rib_kind = match function_kind {
 670             FnKind::ItemFn(_, generics, ..) => {
 671                 self.visit_generics(generics);
 672                 ItemRibKind
 673             }
 674             FnKind::Method(_, sig, _, _) => {
 675                 self.visit_generics(&sig.generics);
 676                 MethodRibKind(!sig.decl.has_self())
 677             }
 678             FnKind::Closure(_) => ClosureRibKind(node_id),
 679         };
 680
 681         // Create a value rib for the function.
 682         self.ribs[ValueNS].push(Rib::new(rib_kind));
 683
 684         // Create a label rib for the function.
 685         self.label_ribs.push(Rib::new(rib_kind));
 686
 687         // Add each argument to the rib.
 688         let mut bindings_list = FxHashMap();
 689         for argument in &declaration.inputs {
 690             self.resolve_pattern(&argument.pat, PatternSource::FnParam, &mut bindings_list);
 691
 692             self.visit_ty(&argument.ty);
 693
 694             debug!("(resolving function) recorded argument");
 695         }
 696         visit::walk_fn_ret_ty(self, &declaration.output);
 697
 698         // Resolve the function body.
 699         match function_kind {
 700             FnKind::ItemFn(.., body) |
 701             FnKind::Method(.., body) => {
 702                 self.visit_block(body);
 703             }
 704             FnKind::Closure(body) => {
 705                 self.visit_expr(body);
 706             }
 707         };
 708
 709         debug!("(resolving function) leaving function");
 710
 711         self.label_ribs.pop();
 712         self.ribs[ValueNS].pop();
 713     }
 714     fn visit_generics(&mut self, generics: &'tcx Generics) {
 715         // For type parameter defaults, we have to ban access
 716         // to following type parameters, as the Substs can only
 717         // provide previous type parameters as they're built.
 718         let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
 719         default_ban_rib.bindings.extend(generics.ty_params.iter()
 720             .skip_while(|p| p.default.is_none())
 721             .map(|p| (Ident::with_empty_ctxt(p.ident.name), Def::Err)));
 722
 723         for param in &generics.ty_params {
 724             for bound in &param.bounds {
 725                 self.visit_ty_param_bound(bound);
 726             }
 727
 728             if let Some(ref ty) = param.default {
 729                 self.ribs[TypeNS].push(default_ban_rib);
 730                 self.visit_ty(ty);
 731                 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
 732             }
 733
 734             // Allow all following defaults to refer to this type parameter.
 735             default_ban_rib.bindings.remove(&Ident::with_empty_ctxt(param.ident.name));
 736         }
 737         for lt in &generics.lifetimes { self.visit_lifetime_def(lt); }
 738         for p in &generics.where_clause.predicates { self.visit_where_predicate(p); }
 739     }
 740 }
 741
 742 pub type ErrorMessage = Option<(Span, String)>;
 743
 744 #[derive(Copy, Clone)]
 745 enum TypeParameters<'a, 'b> {
 746     NoTypeParameters,
 747     HasTypeParameters(// Type parameters.
 748                       &'b Generics,
 749
 750                       // The kind of the rib used for type parameters.
 751                       RibKind<'a>),
 752 }
 753
 754 // The rib kind controls the translation of local
 755 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 756 #[derive(Copy, Clone, Debug)]
 757 enum RibKind<'a> {
 758     // No translation needs to be applied.
 759     NormalRibKind,
 760
 761     // We passed through a closure scope at the given node ID.
 762     // Translate upvars as appropriate.
 763     ClosureRibKind(NodeId /* func id */),
 764
 765     // We passed through an impl or trait and are now in one of its
 766     // methods. Allow references to ty params that impl or trait
 767     // binds. Disallow any other upvars (including other ty params that are
 768     // upvars).
 769     //
 770     // The boolean value represents the fact that this method is static or not.
 771     MethodRibKind(bool),
 772
 773     // We passed through an item scope. Disallow upvars.
 774     ItemRibKind,
 775
 776     // We're in a constant item. Can't refer to dynamic stuff.
 777     ConstantItemRibKind,
 778
 779     // We passed through a module.
 780     ModuleRibKind(Module<'a>),
 781
 782     // We passed through a `macro_rules!` statement
 783     MacroDefinition(DefId),
 784
 785     // All bindings in this rib are type parameters that can't be used
 786     // from the default of a type parameter because they're not declared
 787     // before said type parameter. Also see the `visit_generics` override.
 788     ForwardTyParamBanRibKind,
 789 }
 790
 791 /// One local scope.
 792 #[derive(Debug)]
 793 struct Rib<'a> {
 794     bindings: FxHashMap<Ident, Def>,
 795     kind: RibKind<'a>,
 796 }
 797
 798 impl<'a> Rib<'a> {
 799     fn new(kind: RibKind<'a>) -> Rib<'a> {
 800         Rib {
 801             bindings: FxHashMap(),
 802             kind: kind,
 803         }
 804     }
 805 }
 806
 807 enum LexicalScopeBinding<'a> {
 808     Item(&'a NameBinding<'a>),
 809     Def(Def),
 810 }
 811
 812 impl<'a> LexicalScopeBinding<'a> {
 813     fn item(self) -> Option<&'a NameBinding<'a>> {
 814         match self {
 815             LexicalScopeBinding::Item(binding) => Some(binding),
 816             _ => None,
 817         }
 818     }
 819
 820     fn def(self) -> Def {
 821         match self {
 822             LexicalScopeBinding::Item(binding) => binding.def(),
 823             LexicalScopeBinding::Def(def) => def,
 824         }
 825     }
 826 }
 827
 828 #[derive(Clone)]
 829 enum PathResult<'a> {
 830     Module(Module<'a>),
 831     NonModule(PathResolution),
 832     Indeterminate,
 833     Failed(String, bool /* is the error from the last segment? */),
 834 }
 835
 836 enum ModuleKind {
 837     Block(NodeId),
 838     Def(Def, Name),
 839 }
 840
 841 /// One node in the tree of modules.
 842 pub struct ModuleData<'a> {
 843     parent: Option<Module<'a>>,
 844     kind: ModuleKind,
 845
 846     // The def id of the closest normal module (`mod`) ancestor (including this module).
 847     normal_ancestor_id: DefId,
 848
 849     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
 850     legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, Span, MacroKind)>>,
 851     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 852
 853     // Macro invocations that can expand into items in this module.
 854     unresolved_invocations: RefCell<FxHashSet<Mark>>,
 855
 856     no_implicit_prelude: bool,
 857
 858     glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
 859     globs: RefCell<Vec<&'a ImportDirective<'a>>>,
 860
 861     // Used to memoize the traits in this module for faster searches through all traits in scope.
 862     traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
 863
 864     // Whether this module is populated. If not populated, any attempt to
 865     // access the children must be preceded with a
 866     // `populate_module_if_necessary` call.
 867     populated: Cell<bool>,
 868 }
 869
 870 pub type Module<'a> = &'a ModuleData<'a>;
 871
 872 impl<'a> ModuleData<'a> {
 873     fn new(parent: Option<Module<'a>>, kind: ModuleKind, normal_ancestor_id: DefId) -> Self {
 874         ModuleData {
 875             parent: parent,
 876             kind: kind,
 877             normal_ancestor_id: normal_ancestor_id,
 878             resolutions: RefCell::new(FxHashMap()),
 879             legacy_macro_resolutions: RefCell::new(Vec::new()),
 880             macro_resolutions: RefCell::new(Vec::new()),
 881             unresolved_invocations: RefCell::new(FxHashSet()),
 882             no_implicit_prelude: false,
 883             glob_importers: RefCell::new(Vec::new()),
 884             globs: RefCell::new((Vec::new())),
 885             traits: RefCell::new(None),
 886             populated: Cell::new(normal_ancestor_id.is_local()),
 887         }
 888     }
 889
 890     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 891         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 892             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 893         }
 894     }
 895
 896     fn def(&self) -> Option<Def> {
 897         match self.kind {
 898             ModuleKind::Def(def, _) => Some(def),
 899             _ => None,
 900         }
 901     }
 902
 903     fn def_id(&self) -> Option<DefId> {
 904         self.def().as_ref().map(Def::def_id)
 905     }
 906
 907     // `self` resolves to the first module ancestor that `is_normal`.
 908     fn is_normal(&self) -> bool {
 909         match self.kind {
 910             ModuleKind::Def(Def::Mod(_), _) => true,
 911             _ => false,
 912         }
 913     }
 914
 915     fn is_trait(&self) -> bool {
 916         match self.kind {
 917             ModuleKind::Def(Def::Trait(_), _) => true,
 918             _ => false,
 919         }
 920     }
 921
 922     fn is_local(&self) -> bool {
 923         self.normal_ancestor_id.is_local()
 924     }
 925
 926     fn nearest_item_scope(&'a self) -> Module<'a> {
 927         if self.is_trait() { self.parent.unwrap() } else { self }
 928     }
 929 }
 930
 931 impl<'a> fmt::Debug for ModuleData<'a> {
 932     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 933         write!(f, "{:?}", self.def())
 934     }
 935 }
 936
 937 // Records a possibly-private value, type, or module definition.
 938 #[derive(Clone, Debug)]
 939 pub struct NameBinding<'a> {
 940     kind: NameBindingKind<'a>,
 941     expansion: Mark,
 942     span: Span,
 943     vis: ty::Visibility,
 944 }
 945
 946 pub trait ToNameBinding<'a> {
 947     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 948 }
 949
 950 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 951     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 952         self
 953     }
 954 }
 955
 956 #[derive(Clone, Debug)]
 957 enum NameBindingKind<'a> {
 958     Def(Def),
 959     Module(Module<'a>),
 960     Import {
 961         binding: &'a NameBinding<'a>,
 962         directive: &'a ImportDirective<'a>,
 963         used: Cell<bool>,
 964         legacy_self_import: bool,
 965     },
 966     Ambiguity {
 967         b1: &'a NameBinding<'a>,
 968         b2: &'a NameBinding<'a>,
 969         legacy: bool,
 970     }
 971 }
 972
 973 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 974
 975 struct AmbiguityError<'a> {
 976     span: Span,
 977     name: Name,
 978     lexical: bool,
 979     b1: &'a NameBinding<'a>,
 980     b2: &'a NameBinding<'a>,
 981     legacy: bool,
 982 }
 983
 984 impl<'a> NameBinding<'a> {
 985     fn module(&self) -> Option<Module<'a>> {
 986         match self.kind {
 987             NameBindingKind::Module(module) => Some(module),
 988             NameBindingKind::Import { binding, .. } => binding.module(),
 989             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 990             _ => None,
 991         }
 992     }
 993
 994     fn def(&self) -> Def {
 995         match self.kind {
 996             NameBindingKind::Def(def) => def,
 997             NameBindingKind::Module(module) => module.def().unwrap(),
 998             NameBindingKind::Import { binding, .. } => binding.def(),
 999             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1000             NameBindingKind::Ambiguity { .. } => Def::Err,
1001         }
1002     }
1003
1004     fn def_ignoring_ambiguity(&self) -> Def {
1005         match self.kind {
1006             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1007             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1008             _ => self.def(),
1009         }
1010     }
1011
1012     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1013         resolver.get_macro(self.def_ignoring_ambiguity())
1014     }
1015
1016     // We sometimes need to treat variants as `pub` for backwards compatibility
1017     fn pseudo_vis(&self) -> ty::Visibility {
1018         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1019     }
1020
1021     fn is_variant(&self) -> bool {
1022         match self.kind {
1023             NameBindingKind::Def(Def::Variant(..)) |
1024             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1025             _ => false,
1026         }
1027     }
1028
1029     fn is_extern_crate(&self) -> bool {
1030         match self.kind {
1031             NameBindingKind::Import {
1032                 directive: &ImportDirective {
1033                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1034                 }, ..
1035             } => true,
1036             _ => false,
1037         }
1038     }
1039
1040     fn is_import(&self) -> bool {
1041         match self.kind {
1042             NameBindingKind::Import { .. } => true,
1043             _ => false,
1044         }
1045     }
1046
1047     fn is_glob_import(&self) -> bool {
1048         match self.kind {
1049             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1050             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1051             _ => false,
1052         }
1053     }
1054
1055     fn is_importable(&self) -> bool {
1056         match self.def() {
1057             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1058             _ => true,
1059         }
1060     }
1061 }
1062
1063 /// Interns the names of the primitive types.
1064 struct PrimitiveTypeTable {
1065     primitive_types: FxHashMap<Name, PrimTy>,
1066 }
1067
1068 impl PrimitiveTypeTable {
1069     fn new() -> PrimitiveTypeTable {
1070         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1071
1072         table.intern("bool", TyBool);
1073         table.intern("char", TyChar);
1074         table.intern("f32", TyFloat(FloatTy::F32));
1075         table.intern("f64", TyFloat(FloatTy::F64));
1076         table.intern("isize", TyInt(IntTy::Is));
1077         table.intern("i8", TyInt(IntTy::I8));
1078         table.intern("i16", TyInt(IntTy::I16));
1079         table.intern("i32", TyInt(IntTy::I32));
1080         table.intern("i64", TyInt(IntTy::I64));
1081         table.intern("i128", TyInt(IntTy::I128));
1082         table.intern("str", TyStr);
1083         table.intern("usize", TyUint(UintTy::Us));
1084         table.intern("u8", TyUint(UintTy::U8));
1085         table.intern("u16", TyUint(UintTy::U16));
1086         table.intern("u32", TyUint(UintTy::U32));
1087         table.intern("u64", TyUint(UintTy::U64));
1088         table.intern("u128", TyUint(UintTy::U128));
1089         table
1090     }
1091
1092     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1093         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1094     }
1095 }
1096
1097 /// The main resolver class.
1098 pub struct Resolver<'a> {
1099     session: &'a Session,
1100
1101     pub definitions: Definitions,
1102
1103     graph_root: Module<'a>,
1104
1105     prelude: Option<Module<'a>>,
1106
1107     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1108
1109     // Names of fields of an item `DefId` accessible with dot syntax.
1110     // Used for hints during error reporting.
1111     field_names: FxHashMap<DefId, Vec<Name>>,
1112
1113     // All imports known to succeed or fail.
1114     determined_imports: Vec<&'a ImportDirective<'a>>,
1115
1116     // All non-determined imports.
1117     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1118
1119     // The module that represents the current item scope.
1120     current_module: Module<'a>,
1121
1122     // The current set of local scopes for types and values.
1123     // FIXME #4948: Reuse ribs to avoid allocation.
1124     ribs: PerNS<Vec<Rib<'a>>>,
1125
1126     // The current set of local scopes, for labels.
1127     label_ribs: Vec<Rib<'a>>,
1128
1129     // The trait that the current context can refer to.
1130     current_trait_ref: Option<(DefId, TraitRef)>,
1131
1132     // The current self type if inside an impl (used for better errors).
1133     current_self_type: Option<Ty>,
1134
1135     // The idents for the primitive types.
1136     primitive_type_table: PrimitiveTypeTable,
1137
1138     def_map: DefMap,
1139     pub freevars: FreevarMap,
1140     freevars_seen: NodeMap<NodeMap<usize>>,
1141     pub export_map: ExportMap,
1142     pub trait_map: TraitMap,
1143
1144     // A map from nodes to anonymous modules.
1145     // Anonymous modules are pseudo-modules that are implicitly created around items
1146     // contained within blocks.
1147     //
1148     // For example, if we have this:
1149     //
1150     //  fn f() {
1151     //      fn g() {
1152     //          ...
1153     //      }
1154     //  }
1155     //
1156     // There will be an anonymous module created around `g` with the ID of the
1157     // entry block for `f`.
1158     block_map: NodeMap<Module<'a>>,
1159     module_map: FxHashMap<DefId, Module<'a>>,
1160     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1161
1162     pub make_glob_map: bool,
1163     // Maps imports to the names of items actually imported (this actually maps
1164     // all imports, but only glob imports are actually interesting).
1165     pub glob_map: GlobMap,
1166
1167     used_imports: FxHashSet<(NodeId, Namespace)>,
1168     pub maybe_unused_trait_imports: NodeSet,
1169
1170     privacy_errors: Vec<PrivacyError<'a>>,
1171     ambiguity_errors: Vec<AmbiguityError<'a>>,
1172     gated_errors: FxHashSet<Span>,
1173     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1174
1175     arenas: &'a ResolverArenas<'a>,
1176     dummy_binding: &'a NameBinding<'a>,
1177     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1178
1179     crate_loader: &'a mut CrateLoader,
1180     macro_names: FxHashSet<Name>,
1181     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1182     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1183     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1184     macro_defs: FxHashMap<Mark, DefId>,
1185     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1186     macro_exports: Vec<Export>,
1187     pub whitelisted_legacy_custom_derives: Vec<Name>,
1188     pub found_unresolved_macro: bool,
1189
1190     // Maps the `Mark` of an expansion to its containing module or block.
1191     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1192
1193     // Avoid duplicated errors for "name already defined".
1194     name_already_seen: FxHashMap<Name, Span>,
1195
1196     // If `#![feature(proc_macro)]` is set
1197     proc_macro_enabled: bool,
1198
1199     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1200     warned_proc_macros: FxHashSet<Name>,
1201
1202     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1203
1204     // This table maps struct IDs into struct constructor IDs,
1205     // it's not used during normal resolution, only for better error reporting.
1206     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1207 }
1208
1209 pub struct ResolverArenas<'a> {
1210     modules: arena::TypedArena<ModuleData<'a>>,
1211     local_modules: RefCell<Vec<Module<'a>>>,
1212     name_bindings: arena::TypedArena<NameBinding<'a>>,
1213     import_directives: arena::TypedArena<ImportDirective<'a>>,
1214     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1215     invocation_data: arena::TypedArena<InvocationData<'a>>,
1216     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1217 }
1218
1219 impl<'a> ResolverArenas<'a> {
1220     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1221         let module = self.modules.alloc(module);
1222         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1223             self.local_modules.borrow_mut().push(module);
1224         }
1225         module
1226     }
1227     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1228         self.local_modules.borrow()
1229     }
1230     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1231         self.name_bindings.alloc(name_binding)
1232     }
1233     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1234                               -> &'a ImportDirective {
1235         self.import_directives.alloc(import_directive)
1236     }
1237     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1238         self.name_resolutions.alloc(Default::default())
1239     }
1240     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1241                              -> &'a InvocationData<'a> {
1242         self.invocation_data.alloc(expansion_data)
1243     }
1244     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1245         self.legacy_bindings.alloc(binding)
1246     }
1247 }
1248
1249 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1250     fn parent(self, id: DefId) -> Option<DefId> {
1251         match id.krate {
1252             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1253             _ => self.session.cstore.def_key(id).parent,
1254         }.map(|index| DefId { index: index, ..id })
1255     }
1256 }
1257
1258 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1259     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1260         let namespace = if is_value { ValueNS } else { TypeNS };
1261         let hir::Path { ref segments, span, ref mut def } = *path;
1262         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1263         match self.resolve_path(&path, Some(namespace), Some(span)) {
1264             PathResult::Module(module) => *def = module.def().unwrap(),
1265             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1266                 *def = path_res.base_def(),
1267             PathResult::NonModule(..) => match self.resolve_path(&path, None, Some(span)) {
1268                 PathResult::Failed(msg, _) => {
1269                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1270                 }
1271                 _ => {}
1272             },
1273             PathResult::Indeterminate => unreachable!(),
1274             PathResult::Failed(msg, _) => {
1275                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1276             }
1277         }
1278     }
1279
1280     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1281         self.def_map.get(&id).cloned()
1282     }
1283
1284     fn definitions(&mut self) -> &mut Definitions {
1285         &mut self.definitions
1286     }
1287 }
1288
1289 impl<'a> Resolver<'a> {
1290     pub fn new(session: &'a Session,
1291                krate: &Crate,
1292                make_glob_map: MakeGlobMap,
1293                crate_loader: &'a mut CrateLoader,
1294                arenas: &'a ResolverArenas<'a>)
1295                -> Resolver<'a> {
1296         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1297         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1298         let graph_root = arenas.alloc_module(ModuleData {
1299             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1300             ..ModuleData::new(None, root_module_kind, root_def_id)
1301         });
1302         let mut module_map = FxHashMap();
1303         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1304
1305         let mut definitions = Definitions::new();
1306         DefCollector::new(&mut definitions).collect_root();
1307
1308         let mut invocations = FxHashMap();
1309         invocations.insert(Mark::root(),
1310                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1311
1312         let features = session.features.borrow();
1313
1314         let mut macro_defs = FxHashMap();
1315         macro_defs.insert(Mark::root(), root_def_id);
1316
1317         Resolver {
1318             session: session,
1319
1320             definitions: definitions,
1321
1322             // The outermost module has def ID 0; this is not reflected in the
1323             // AST.
1324             graph_root: graph_root,
1325             prelude: None,
1326
1327             trait_item_map: FxHashMap(),
1328             field_names: FxHashMap(),
1329
1330             determined_imports: Vec::new(),
1331             indeterminate_imports: Vec::new(),
1332
1333             current_module: graph_root,
1334             ribs: PerNS {
1335                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1336                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1337                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1338             },
1339             label_ribs: Vec::new(),
1340
1341             current_trait_ref: None,
1342             current_self_type: None,
1343
1344             primitive_type_table: PrimitiveTypeTable::new(),
1345
1346             def_map: NodeMap(),
1347             freevars: NodeMap(),
1348             freevars_seen: NodeMap(),
1349             export_map: NodeMap(),
1350             trait_map: NodeMap(),
1351             module_map: module_map,
1352             block_map: NodeMap(),
1353             extern_crate_roots: FxHashMap(),
1354
1355             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1356             glob_map: NodeMap(),
1357
1358             used_imports: FxHashSet(),
1359             maybe_unused_trait_imports: NodeSet(),
1360
1361             privacy_errors: Vec::new(),
1362             ambiguity_errors: Vec::new(),
1363             gated_errors: FxHashSet(),
1364             disallowed_shadowing: Vec::new(),
1365
1366             arenas: arenas,
1367             dummy_binding: arenas.alloc_name_binding(NameBinding {
1368                 kind: NameBindingKind::Def(Def::Err),
1369                 expansion: Mark::root(),
1370                 span: DUMMY_SP,
1371                 vis: ty::Visibility::Public,
1372             }),
1373
1374             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1375             use_extern_macros: features.use_extern_macros || features.proc_macro,
1376
1377             crate_loader: crate_loader,
1378             macro_names: FxHashSet(),
1379             global_macros: FxHashMap(),
1380             lexical_macro_resolutions: Vec::new(),
1381             macro_map: FxHashMap(),
1382             macro_exports: Vec::new(),
1383             invocations: invocations,
1384             macro_defs: macro_defs,
1385             local_macro_def_scopes: FxHashMap(),
1386             name_already_seen: FxHashMap(),
1387             whitelisted_legacy_custom_derives: Vec::new(),
1388             proc_macro_enabled: features.proc_macro,
1389             warned_proc_macros: FxHashSet(),
1390             potentially_unused_imports: Vec::new(),
1391             struct_constructors: DefIdMap(),
1392             found_unresolved_macro: false,
1393         }
1394     }
1395
1396     pub fn arenas() -> ResolverArenas<'a> {
1397         ResolverArenas {
1398             modules: arena::TypedArena::new(),
1399             local_modules: RefCell::new(Vec::new()),
1400             name_bindings: arena::TypedArena::new(),
1401             import_directives: arena::TypedArena::new(),
1402             name_resolutions: arena::TypedArena::new(),
1403             invocation_data: arena::TypedArena::new(),
1404             legacy_bindings: arena::TypedArena::new(),
1405         }
1406     }
1407
1408     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1409         PerNS {
1410             type_ns: f(self, TypeNS),
1411             value_ns: f(self, ValueNS),
1412             macro_ns: match self.use_extern_macros {
1413                 true => Some(f(self, MacroNS)),
1414                 false => None,
1415             },
1416         }
1417     }
1418
1419     /// Entry point to crate resolution.
1420     pub fn resolve_crate(&mut self, krate: &Crate) {
1421         ImportResolver { resolver: self }.finalize_imports();
1422         self.current_module = self.graph_root;
1423         self.finalize_current_module_macro_resolutions();
1424         visit::walk_crate(self, krate);
1425
1426         check_unused::check_crate(self, krate);
1427         self.report_errors();
1428         self.crate_loader.postprocess(krate);
1429     }
1430
1431     fn new_module(&self, parent: Module<'a>, kind: ModuleKind, normal_ancestor_id: DefId)
1432                   -> Module<'a> {
1433         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id))
1434     }
1435
1436     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1437                   -> bool /* true if an error was reported */ {
1438         match binding.kind {
1439             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1440                     if !used.get() => {
1441                 used.set(true);
1442                 directive.used.set(true);
1443                 if legacy_self_import {
1444                     self.warn_legacy_self_import(directive);
1445                     return false;
1446                 }
1447                 self.used_imports.insert((directive.id, ns));
1448                 self.add_to_glob_map(directive.id, ident);
1449                 self.record_use(ident, ns, binding, span)
1450             }
1451             NameBindingKind::Import { .. } => false,
1452             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1453                 self.ambiguity_errors.push(AmbiguityError {
1454                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1455                 });
1456                 if legacy {
1457                     self.record_use(ident, ns, b1, span);
1458                 }
1459                 !legacy
1460             }
1461             _ => false
1462         }
1463     }
1464
1465     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1466         if self.make_glob_map {
1467             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1468         }
1469     }
1470
1471     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1472     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1473     /// `ident` in the first scope that defines it (or None if no scopes define it).
1474     ///
1475     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1476     /// the items are defined in the block. For example,
1477     /// ```rust
1478     /// fn f() {
1479     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1480     ///    let g = || {};
1481     ///    fn g() {}
1482     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1483     /// }
1484     /// ```
1485     ///
1486     /// Invariant: This must only be called during main resolution, not during
1487     /// import resolution.
1488     fn resolve_ident_in_lexical_scope(&mut self,
1489                                       mut ident: Ident,
1490                                       ns: Namespace,
1491                                       record_used: Option<Span>)
1492                                       -> Option<LexicalScopeBinding<'a>> {
1493         if ns == TypeNS {
1494             ident = ident.unhygienize();
1495         }
1496
1497         // Walk backwards up the ribs in scope.
1498         for i in (0 .. self.ribs[ns].len()).rev() {
1499             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1500                 // The ident resolves to a type parameter or local variable.
1501                 return Some(LexicalScopeBinding::Def(
1502                     self.adjust_local_def(ns, i, def, record_used)
1503                 ));
1504             }
1505
1506             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1507                 let item = self.resolve_ident_in_module(module, ident, ns, false, record_used);
1508                 if let Ok(binding) = item {
1509                     // The ident resolves to an item.
1510                     return Some(LexicalScopeBinding::Item(binding));
1511                 }
1512
1513                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1514                 } else if !module.no_implicit_prelude {
1515                     return self.prelude.and_then(|prelude| {
1516                         self.resolve_ident_in_module(prelude, ident, ns, false, None).ok()
1517                     }).map(LexicalScopeBinding::Item)
1518                 } else {
1519                     return None;
1520                 }
1521             }
1522
1523             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1524                 // If an invocation of this macro created `ident`, give up on `ident`
1525                 // and switch to `ident`'s source from the macro definition.
1526                 let ctxt_data = ident.ctxt.data();
1527                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1528                     ident.ctxt = ctxt_data.prev_ctxt;
1529                 }
1530             }
1531         }
1532
1533         None
1534     }
1535
1536     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext) -> Module<'a> {
1537         let mut ctxt_data = crate_var_ctxt.data();
1538         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1539             ctxt_data = ctxt_data.prev_ctxt.data();
1540         }
1541         let module = self.macro_def_scope(ctxt_data.outer_mark);
1542         if module.is_local() { self.graph_root } else { module }
1543     }
1544
1545     // AST resolution
1546     //
1547     // We maintain a list of value ribs and type ribs.
1548     //
1549     // Simultaneously, we keep track of the current position in the module
1550     // graph in the `current_module` pointer. When we go to resolve a name in
1551     // the value or type namespaces, we first look through all the ribs and
1552     // then query the module graph. When we resolve a name in the module
1553     // namespace, we can skip all the ribs (since nested modules are not
1554     // allowed within blocks in Rust) and jump straight to the current module
1555     // graph node.
1556     //
1557     // Named implementations are handled separately. When we find a method
1558     // call, we consult the module node to find all of the implementations in
1559     // scope. This information is lazily cached in the module node. We then
1560     // generate a fake "implementation scope" containing all the
1561     // implementations thus found, for compatibility with old resolve pass.
1562
1563     fn with_scope<F>(&mut self, id: NodeId, f: F)
1564         where F: FnOnce(&mut Resolver)
1565     {
1566         let id = self.definitions.local_def_id(id);
1567         let module = self.module_map.get(&id).cloned(); // clones a reference
1568         if let Some(module) = module {
1569             // Move down in the graph.
1570             let orig_module = replace(&mut self.current_module, module);
1571             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1572             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1573
1574             self.finalize_current_module_macro_resolutions();
1575             f(self);
1576
1577             self.current_module = orig_module;
1578             self.ribs[ValueNS].pop();
1579             self.ribs[TypeNS].pop();
1580         } else {
1581             f(self);
1582         }
1583     }
1584
1585     /// Searches the current set of local scopes for labels.
1586     /// Stops after meeting a closure.
1587     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1588         for rib in self.label_ribs.iter().rev() {
1589             match rib.kind {
1590                 NormalRibKind => {
1591                     // Continue
1592                 }
1593                 MacroDefinition(def) => {
1594                     // If an invocation of this macro created `ident`, give up on `ident`
1595                     // and switch to `ident`'s source from the macro definition.
1596                     let ctxt_data = ident.ctxt.data();
1597                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1598                         ident.ctxt = ctxt_data.prev_ctxt;
1599                     }
1600                 }
1601                 _ => {
1602                     // Do not resolve labels across function boundary
1603                     return None;
1604                 }
1605             }
1606             let result = rib.bindings.get(&ident).cloned();
1607             if result.is_some() {
1608                 return result;
1609             }
1610         }
1611         None
1612     }
1613
1614     fn resolve_item(&mut self, item: &Item) {
1615         let name = item.ident.name;
1616
1617         debug!("(resolving item) resolving {}", name);
1618
1619         self.check_proc_macro_attrs(&item.attrs);
1620
1621         match item.node {
1622             ItemKind::Enum(_, ref generics) |
1623             ItemKind::Ty(_, ref generics) |
1624             ItemKind::Struct(_, ref generics) |
1625             ItemKind::Union(_, ref generics) |
1626             ItemKind::Fn(.., ref generics, _) => {
1627                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1628                                              |this| visit::walk_item(this, item));
1629             }
1630
1631             ItemKind::DefaultImpl(_, ref trait_ref) => {
1632                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1633                     // Resolve type arguments in trait path
1634                     visit::walk_trait_ref(this, trait_ref);
1635                 });
1636             }
1637             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1638                 self.resolve_implementation(generics,
1639                                             opt_trait_ref,
1640                                             &self_type,
1641                                             item.id,
1642                                             impl_items),
1643
1644             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1645                 // Create a new rib for the trait-wide type parameters.
1646                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1647                     let local_def_id = this.definitions.local_def_id(item.id);
1648                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1649                         this.visit_generics(generics);
1650                         walk_list!(this, visit_ty_param_bound, bounds);
1651
1652                         for trait_item in trait_items {
1653                             this.check_proc_macro_attrs(&trait_item.attrs);
1654
1655                             match trait_item.node {
1656                                 TraitItemKind::Const(_, ref default) => {
1657                                     // Only impose the restrictions of
1658                                     // ConstRibKind if there's an actual constant
1659                                     // expression in a provided default.
1660                                     if default.is_some() {
1661                                         this.with_constant_rib(|this| {
1662                                             visit::walk_trait_item(this, trait_item)
1663                                         });
1664                                     } else {
1665                                         visit::walk_trait_item(this, trait_item)
1666                                     }
1667                                 }
1668                                 TraitItemKind::Method(ref sig, _) => {
1669                                     let type_parameters =
1670                                         HasTypeParameters(&sig.generics,
1671                                                           MethodRibKind(!sig.decl.has_self()));
1672                                     this.with_type_parameter_rib(type_parameters, |this| {
1673                                         visit::walk_trait_item(this, trait_item)
1674                                     });
1675                                 }
1676                                 TraitItemKind::Type(..) => {
1677                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1678                                         visit::walk_trait_item(this, trait_item)
1679                                     });
1680                                 }
1681                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1682                             };
1683                         }
1684                     });
1685                 });
1686             }
1687
1688             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1689                 self.with_scope(item.id, |this| {
1690                     visit::walk_item(this, item);
1691                 });
1692             }
1693
1694             ItemKind::Const(..) | ItemKind::Static(..) => {
1695                 self.with_constant_rib(|this| {
1696                     visit::walk_item(this, item);
1697                 });
1698             }
1699
1700             ItemKind::Use(ref view_path) => {
1701                 match view_path.node {
1702                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1703                         // Resolve prefix of an import with empty braces (issue #28388).
1704                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1705                     }
1706                     _ => {}
1707                 }
1708             }
1709
1710             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) => {
1711                 // do nothing, these are just around to be encoded
1712             }
1713
1714             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1715         }
1716     }
1717
1718     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1719         where F: FnOnce(&mut Resolver)
1720     {
1721         match type_parameters {
1722             HasTypeParameters(generics, rib_kind) => {
1723                 let mut function_type_rib = Rib::new(rib_kind);
1724                 let mut seen_bindings = FxHashMap();
1725                 for type_parameter in &generics.ty_params {
1726                     let name = type_parameter.ident.name;
1727                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1728
1729                     if seen_bindings.contains_key(&name) {
1730                         let span = seen_bindings.get(&name).unwrap();
1731                         resolve_error(self,
1732                                       type_parameter.span,
1733                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1734                                                                                           span));
1735                     }
1736                     seen_bindings.entry(name).or_insert(type_parameter.span);
1737
1738                     // plain insert (no renaming)
1739                     let def_id = self.definitions.local_def_id(type_parameter.id);
1740                     let def = Def::TyParam(def_id);
1741                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1742                     self.record_def(type_parameter.id, PathResolution::new(def));
1743                 }
1744                 self.ribs[TypeNS].push(function_type_rib);
1745             }
1746
1747             NoTypeParameters => {
1748                 // Nothing to do.
1749             }
1750         }
1751
1752         f(self);
1753
1754         if let HasTypeParameters(..) = type_parameters {
1755             self.ribs[TypeNS].pop();
1756         }
1757     }
1758
1759     fn with_label_rib<F>(&mut self, f: F)
1760         where F: FnOnce(&mut Resolver)
1761     {
1762         self.label_ribs.push(Rib::new(NormalRibKind));
1763         f(self);
1764         self.label_ribs.pop();
1765     }
1766
1767     fn with_constant_rib<F>(&mut self, f: F)
1768         where F: FnOnce(&mut Resolver)
1769     {
1770         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1771         self.ribs[TypeNS].push(Rib::new(ConstantItemRibKind));
1772         f(self);
1773         self.ribs[TypeNS].pop();
1774         self.ribs[ValueNS].pop();
1775     }
1776
1777     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1778         where F: FnOnce(&mut Resolver) -> T
1779     {
1780         // Handle nested impls (inside fn bodies)
1781         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1782         let result = f(self);
1783         self.current_self_type = previous_value;
1784         result
1785     }
1786
1787     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1788         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1789     {
1790         let mut new_val = None;
1791         let mut new_id = None;
1792         if let Some(trait_ref) = opt_trait_ref {
1793             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1794                                               &trait_ref.path, PathSource::Trait).base_def();
1795             if def != Def::Err {
1796                 new_val = Some((def.def_id(), trait_ref.clone()));
1797                 new_id = Some(def.def_id());
1798             }
1799         }
1800         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1801         let result = f(self, new_id);
1802         self.current_trait_ref = original_trait_ref;
1803         result
1804     }
1805
1806     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1807         where F: FnOnce(&mut Resolver)
1808     {
1809         let mut self_type_rib = Rib::new(NormalRibKind);
1810
1811         // plain insert (no renaming, types are not currently hygienic....)
1812         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1813         self.ribs[TypeNS].push(self_type_rib);
1814         f(self);
1815         self.ribs[TypeNS].pop();
1816     }
1817
1818     fn resolve_implementation(&mut self,
1819                               generics: &Generics,
1820                               opt_trait_reference: &Option<TraitRef>,
1821                               self_type: &Ty,
1822                               item_id: NodeId,
1823                               impl_items: &[ImplItem]) {
1824         // If applicable, create a rib for the type parameters.
1825         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1826             // Dummy self type for better errors if `Self` is used in the trait path.
1827             this.with_self_rib(Def::SelfTy(None, None), |this| {
1828                 // Resolve the trait reference, if necessary.
1829                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1830                     let item_def_id = this.definitions.local_def_id(item_id);
1831                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1832                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1833                             // Resolve type arguments in trait path
1834                             visit::walk_trait_ref(this, trait_ref);
1835                         }
1836                         // Resolve the self type.
1837                         this.visit_ty(self_type);
1838                         // Resolve the type parameters.
1839                         this.visit_generics(generics);
1840                         this.with_current_self_type(self_type, |this| {
1841                             for impl_item in impl_items {
1842                                 this.check_proc_macro_attrs(&impl_item.attrs);
1843                                 this.resolve_visibility(&impl_item.vis);
1844                                 match impl_item.node {
1845                                     ImplItemKind::Const(..) => {
1846                                         // If this is a trait impl, ensure the const
1847                                         // exists in trait
1848                                         this.check_trait_item(impl_item.ident.name,
1849                                                             ValueNS,
1850                                                             impl_item.span,
1851                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1852                                         visit::walk_impl_item(this, impl_item);
1853                                     }
1854                                     ImplItemKind::Method(ref sig, _) => {
1855                                         // If this is a trait impl, ensure the method
1856                                         // exists in trait
1857                                         this.check_trait_item(impl_item.ident.name,
1858                                                             ValueNS,
1859                                                             impl_item.span,
1860                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1861
1862                                         // We also need a new scope for the method-
1863                                         // specific type parameters.
1864                                         let type_parameters =
1865                                             HasTypeParameters(&sig.generics,
1866                                                             MethodRibKind(!sig.decl.has_self()));
1867                                         this.with_type_parameter_rib(type_parameters, |this| {
1868                                             visit::walk_impl_item(this, impl_item);
1869                                         });
1870                                     }
1871                                     ImplItemKind::Type(ref ty) => {
1872                                         // If this is a trait impl, ensure the type
1873                                         // exists in trait
1874                                         this.check_trait_item(impl_item.ident.name,
1875                                                             TypeNS,
1876                                                             impl_item.span,
1877                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1878
1879                                         this.visit_ty(ty);
1880                                     }
1881                                     ImplItemKind::Macro(_) =>
1882                                         panic!("unexpanded macro in resolve!"),
1883                                 }
1884                             }
1885                         });
1886                     });
1887                 });
1888             });
1889         });
1890     }
1891
1892     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1893         where F: FnOnce(Name, &str) -> ResolutionError
1894     {
1895         // If there is a TraitRef in scope for an impl, then the method must be in the
1896         // trait.
1897         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1898             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1899                 let path_str = path_names_to_string(&trait_ref.path);
1900                 resolve_error(self, span, err(name, &path_str));
1901             }
1902         }
1903     }
1904
1905     fn resolve_local(&mut self, local: &Local) {
1906         // Resolve the type.
1907         walk_list!(self, visit_ty, &local.ty);
1908
1909         // Resolve the initializer.
1910         walk_list!(self, visit_expr, &local.init);
1911
1912         // Resolve the pattern.
1913         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1914     }
1915
1916     // build a map from pattern identifiers to binding-info's.
1917     // this is done hygienically. This could arise for a macro
1918     // that expands into an or-pattern where one 'x' was from the
1919     // user and one 'x' came from the macro.
1920     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1921         let mut binding_map = FxHashMap();
1922
1923         pat.walk(&mut |pat| {
1924             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1925                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1926                     Some(Def::Local(..)) => true,
1927                     _ => false,
1928                 } {
1929                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1930                     binding_map.insert(ident.node, binding_info);
1931                 }
1932             }
1933             true
1934         });
1935
1936         binding_map
1937     }
1938
1939     // check that all of the arms in an or-pattern have exactly the
1940     // same set of bindings, with the same binding modes for each.
1941     fn check_consistent_bindings(&mut self, arm: &Arm) {
1942         if arm.pats.is_empty() {
1943             return;
1944         }
1945
1946         let mut missing_vars = FxHashMap();
1947         let mut inconsistent_vars = FxHashMap();
1948         for (i, p) in arm.pats.iter().enumerate() {
1949             let map_i = self.binding_mode_map(&p);
1950
1951             for (j, q) in arm.pats.iter().enumerate() {
1952                 if i == j {
1953                     continue;
1954                 }
1955
1956                 let map_j = self.binding_mode_map(&q);
1957                 for (&key, &binding_i) in &map_i {
1958                     if map_j.len() == 0 {                   // Account for missing bindings when
1959                         let binding_error = missing_vars    // map_j has none.
1960                             .entry(key.name)
1961                             .or_insert(BindingError {
1962                                 name: key.name,
1963                                 origin: BTreeSet::new(),
1964                                 target: BTreeSet::new(),
1965                             });
1966                         binding_error.origin.insert(binding_i.span);
1967                         binding_error.target.insert(q.span);
1968                     }
1969                     for (&key_j, &binding_j) in &map_j {
1970                         match map_i.get(&key_j) {
1971                             None => {  // missing binding
1972                                 let binding_error = missing_vars
1973                                     .entry(key_j.name)
1974                                     .or_insert(BindingError {
1975                                         name: key_j.name,
1976                                         origin: BTreeSet::new(),
1977                                         target: BTreeSet::new(),
1978                                     });
1979                                 binding_error.origin.insert(binding_j.span);
1980                                 binding_error.target.insert(p.span);
1981                             }
1982                             Some(binding_i) => {  // check consistent binding
1983                                 if binding_i.binding_mode != binding_j.binding_mode {
1984                                     inconsistent_vars
1985                                         .entry(key.name)
1986                                         .or_insert((binding_j.span, binding_i.span));
1987                                 }
1988                             }
1989                         }
1990                     }
1991                 }
1992             }
1993         }
1994         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
1995         missing_vars.sort();
1996         for (_, v) in missing_vars {
1997             resolve_error(self,
1998                           *v.origin.iter().next().unwrap(),
1999                           ResolutionError::VariableNotBoundInPattern(v));
2000         }
2001         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2002         inconsistent_vars.sort();
2003         for (name, v) in inconsistent_vars {
2004             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2005         }
2006     }
2007
2008     fn resolve_arm(&mut self, arm: &Arm) {
2009         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2010
2011         let mut bindings_list = FxHashMap();
2012         for pattern in &arm.pats {
2013             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2014         }
2015
2016         // This has to happen *after* we determine which
2017         // pat_idents are variants
2018         self.check_consistent_bindings(arm);
2019
2020         walk_list!(self, visit_expr, &arm.guard);
2021         self.visit_expr(&arm.body);
2022
2023         self.ribs[ValueNS].pop();
2024     }
2025
2026     fn resolve_block(&mut self, block: &Block) {
2027         debug!("(resolving block) entering block");
2028         // Move down in the graph, if there's an anonymous module rooted here.
2029         let orig_module = self.current_module;
2030         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2031
2032         let mut num_macro_definition_ribs = 0;
2033         if let Some(anonymous_module) = anonymous_module {
2034             debug!("(resolving block) found anonymous module, moving down");
2035             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2036             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2037             self.current_module = anonymous_module;
2038             self.finalize_current_module_macro_resolutions();
2039         } else {
2040             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2041         }
2042
2043         // Descend into the block.
2044         for stmt in &block.stmts {
2045             if let ast::StmtKind::Item(ref item) = stmt.node {
2046                 if let ast::ItemKind::MacroDef(..) = item.node {
2047                     num_macro_definition_ribs += 1;
2048                     let def = self.definitions.local_def_id(item.id);
2049                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2050                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2051                 }
2052             }
2053
2054             self.visit_stmt(stmt);
2055         }
2056
2057         // Move back up.
2058         self.current_module = orig_module;
2059         for _ in 0 .. num_macro_definition_ribs {
2060             self.ribs[ValueNS].pop();
2061             self.label_ribs.pop();
2062         }
2063         self.ribs[ValueNS].pop();
2064         if let Some(_) = anonymous_module {
2065             self.ribs[TypeNS].pop();
2066         }
2067         debug!("(resolving block) leaving block");
2068     }
2069
2070     fn fresh_binding(&mut self,
2071                      ident: &SpannedIdent,
2072                      pat_id: NodeId,
2073                      outer_pat_id: NodeId,
2074                      pat_src: PatternSource,
2075                      bindings: &mut FxHashMap<Ident, NodeId>)
2076                      -> PathResolution {
2077         // Add the binding to the local ribs, if it
2078         // doesn't already exist in the bindings map. (We
2079         // must not add it if it's in the bindings map
2080         // because that breaks the assumptions later
2081         // passes make about or-patterns.)
2082         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2083         match bindings.get(&ident.node).cloned() {
2084             Some(id) if id == outer_pat_id => {
2085                 // `Variant(a, a)`, error
2086                 resolve_error(
2087                     self,
2088                     ident.span,
2089                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2090                         &ident.node.name.as_str())
2091                 );
2092             }
2093             Some(..) if pat_src == PatternSource::FnParam => {
2094                 // `fn f(a: u8, a: u8)`, error
2095                 resolve_error(
2096                     self,
2097                     ident.span,
2098                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2099                         &ident.node.name.as_str())
2100                 );
2101             }
2102             Some(..) if pat_src == PatternSource::Match => {
2103                 // `Variant1(a) | Variant2(a)`, ok
2104                 // Reuse definition from the first `a`.
2105                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2106             }
2107             Some(..) => {
2108                 span_bug!(ident.span, "two bindings with the same name from \
2109                                        unexpected pattern source {:?}", pat_src);
2110             }
2111             None => {
2112                 // A completely fresh binding, add to the lists if it's valid.
2113                 if ident.node.name != keywords::Invalid.name() {
2114                     bindings.insert(ident.node, outer_pat_id);
2115                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2116                 }
2117             }
2118         }
2119
2120         PathResolution::new(def)
2121     }
2122
2123     fn resolve_pattern(&mut self,
2124                        pat: &Pat,
2125                        pat_src: PatternSource,
2126                        // Maps idents to the node ID for the
2127                        // outermost pattern that binds them.
2128                        bindings: &mut FxHashMap<Ident, NodeId>) {
2129         // Visit all direct subpatterns of this pattern.
2130         let outer_pat_id = pat.id;
2131         pat.walk(&mut |pat| {
2132             match pat.node {
2133                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2134                     // First try to resolve the identifier as some existing
2135                     // entity, then fall back to a fresh binding.
2136                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS, None)
2137                                       .and_then(LexicalScopeBinding::item);
2138                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2139                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2140                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2141                         match def {
2142                             Def::StructCtor(_, CtorKind::Const) |
2143                             Def::VariantCtor(_, CtorKind::Const) |
2144                             Def::Const(..) if !always_binding => {
2145                                 // A unit struct/variant or constant pattern.
2146                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2147                                 Some(PathResolution::new(def))
2148                             }
2149                             Def::StructCtor(..) | Def::VariantCtor(..) |
2150                             Def::Const(..) | Def::Static(..) => {
2151                                 // A fresh binding that shadows something unacceptable.
2152                                 resolve_error(
2153                                     self,
2154                                     ident.span,
2155                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2156                                         pat_src.descr(), ident.node.name, binding.unwrap())
2157                                 );
2158                                 None
2159                             }
2160                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2161                                 // These entities are explicitly allowed
2162                                 // to be shadowed by fresh bindings.
2163                                 None
2164                             }
2165                             def => {
2166                                 span_bug!(ident.span, "unexpected definition for an \
2167                                                        identifier in pattern: {:?}", def);
2168                             }
2169                         }
2170                     }).unwrap_or_else(|| {
2171                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2172                     });
2173
2174                     self.record_def(pat.id, resolution);
2175                 }
2176
2177                 PatKind::TupleStruct(ref path, ..) => {
2178                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2179                 }
2180
2181                 PatKind::Path(ref qself, ref path) => {
2182                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2183                 }
2184
2185                 PatKind::Struct(ref path, ..) => {
2186                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2187                 }
2188
2189                 _ => {}
2190             }
2191             true
2192         });
2193
2194         visit::walk_pat(self, pat);
2195     }
2196
2197     // High-level and context dependent path resolution routine.
2198     // Resolves the path and records the resolution into definition map.
2199     // If resolution fails tries several techniques to find likely
2200     // resolution candidates, suggest imports or other help, and report
2201     // errors in user friendly way.
2202     fn smart_resolve_path(&mut self,
2203                           id: NodeId,
2204                           qself: Option<&QSelf>,
2205                           path: &Path,
2206                           source: PathSource)
2207                           -> PathResolution {
2208         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2209         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2210         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2211     }
2212
2213     fn smart_resolve_path_fragment(&mut self,
2214                                    id: NodeId,
2215                                    qself: Option<&QSelf>,
2216                                    path: &[Ident],
2217                                    span: Span,
2218                                    ident_span: Span,
2219                                    source: PathSource)
2220                                    -> PathResolution {
2221         let ns = source.namespace();
2222         let is_expected = &|def| source.is_expected(def);
2223
2224         // Base error is amended with one short label and possibly some longer helps/notes.
2225         let report_errors = |this: &mut Self, def: Option<Def>| {
2226             // Make the base error.
2227             let expected = source.descr_expected();
2228             let path_str = names_to_string(path);
2229             let code = source.error_code(def.is_some());
2230             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2231                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2232                  format!("not a {}", expected), span)
2233             } else {
2234                 let item_str = path[path.len() - 1];
2235                 let (mod_prefix, mod_str) = if path.len() == 1 {
2236                     (format!(""), format!("this scope"))
2237                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2238                     (format!(""), format!("the crate root"))
2239                 } else {
2240                     let mod_path = &path[..path.len() - 1];
2241                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), None) {
2242                         PathResult::Module(module) => module.def(),
2243                         _ => None,
2244                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2245                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2246                 };
2247                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2248                  format!("not found in {}", mod_str), ident_span)
2249             };
2250             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2251
2252             // Emit special messages for unresolved `Self` and `self`.
2253             if is_self_type(path, ns) {
2254                 __diagnostic_used!(E0411);
2255                 err.code("E0411".into());
2256                 err.span_label(span, &format!("`Self` is only available in traits and impls"));
2257                 return err;
2258             }
2259             if is_self_value(path, ns) {
2260                 __diagnostic_used!(E0424);
2261                 err.code("E0424".into());
2262                 err.span_label(span, &format!("`self` value is only available in \
2263                                                methods with `self` parameter"));
2264                 return err;
2265             }
2266
2267             // Try to lookup the name in more relaxed fashion for better error reporting.
2268             let name = path.last().unwrap().name;
2269             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2270             if !candidates.is_empty() {
2271                 // Report import candidates as help and proceed searching for labels.
2272                 show_candidates(&mut err, &candidates, def.is_some());
2273             }
2274             if path.len() == 1 && this.self_type_is_available() {
2275                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2276                     let self_is_available = this.self_value_is_available(path[0].ctxt);
2277                     match candidate {
2278                         AssocSuggestion::Field => {
2279                             err.span_label(span, &format!("did you mean `self.{}`?", path_str));
2280                             if !self_is_available {
2281                                 err.span_label(span, &format!("`self` value is only available in \
2282                                                                methods with `self` parameter"));
2283                             }
2284                         }
2285                         AssocSuggestion::MethodWithSelf if self_is_available => {
2286                             err.span_label(span, &format!("did you mean `self.{}(...)`?",
2287                                                            path_str));
2288                         }
2289                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2290                             err.span_label(span, &format!("did you mean `Self::{}`?", path_str));
2291                         }
2292                     }
2293                     return err;
2294                 }
2295             }
2296
2297             // Try context dependent help if relaxed lookup didn't work.
2298             if let Some(def) = def {
2299                 match (def, source) {
2300                     (Def::Macro(..), _) => {
2301                         err.span_label(span, &format!("did you mean `{}!(...)`?", path_str));
2302                         return err;
2303                     }
2304                     (Def::TyAlias(..), PathSource::Trait) => {
2305                         err.span_label(span, &format!("type aliases cannot be used for traits"));
2306                         return err;
2307                     }
2308                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2309                         ExprKind::Field(_, ident) => {
2310                             err.span_label(parent.span, &format!("did you mean `{}::{}`?",
2311                                                                  path_str, ident.node));
2312                             return err;
2313                         }
2314                         ExprKind::MethodCall(ident, ..) => {
2315                             err.span_label(parent.span, &format!("did you mean `{}::{}(...)`?",
2316                                                                  path_str, ident.node));
2317                             return err;
2318                         }
2319                         _ => {}
2320                     },
2321                     _ if ns == ValueNS && is_struct_like(def) => {
2322                         if let Def::Struct(def_id) = def {
2323                             if let Some((ctor_def, ctor_vis))
2324                                     = this.struct_constructors.get(&def_id).cloned() {
2325                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2326                                     err.span_label(span, &format!("constructor is not visible \
2327                                                                    here due to private fields"));
2328                                 }
2329                             }
2330                         }
2331                         err.span_label(span, &format!("did you mean `{} {{ /* fields */ }}`?",
2332                                                        path_str));
2333                         return err;
2334                     }
2335                     _ => {}
2336                 }
2337             }
2338
2339             // Try Levenshtein if nothing else worked.
2340             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected) {
2341                 err.span_label(ident_span, &format!("did you mean `{}`?", candidate));
2342                 return err;
2343             }
2344
2345             // Fallback label.
2346             err.span_label(base_span, &fallback_label);
2347             err
2348         };
2349         let report_errors = |this: &mut Self, def: Option<Def>| {
2350             report_errors(this, def).emit();
2351             err_path_resolution()
2352         };
2353
2354         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2355                                                            source.defer_to_typeck(),
2356                                                            source.global_by_default()) {
2357             Some(resolution) if resolution.unresolved_segments() == 0 => {
2358                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2359                     resolution
2360                 } else {
2361                     // Add a temporary hack to smooth the transition to new struct ctor
2362                     // visibility rules. See #38932 for more details.
2363                     let mut res = None;
2364                     if let Def::Struct(def_id) = resolution.base_def() {
2365                         if let Some((ctor_def, ctor_vis))
2366                                 = self.struct_constructors.get(&def_id).cloned() {
2367                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2368                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2369                                 self.session.add_lint(lint, id, span,
2370                                     "private struct constructors are not usable through \
2371                                      reexports in outer modules".to_string());
2372                                 res = Some(PathResolution::new(ctor_def));
2373                             }
2374                         }
2375                     }
2376
2377                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2378                 }
2379             }
2380             Some(resolution) if source.defer_to_typeck() => {
2381                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2382                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2383                 // it needs to be added to the trait map.
2384                 if ns == ValueNS {
2385                     let item_name = path.last().unwrap().name;
2386                     let traits = self.get_traits_containing_item(item_name, ns);
2387                     self.trait_map.insert(id, traits);
2388                 }
2389                 resolution
2390             }
2391             _ => report_errors(self, None)
2392         };
2393
2394         if let PathSource::TraitItem(..) = source {} else {
2395             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2396             self.record_def(id, resolution);
2397         }
2398         resolution
2399     }
2400
2401     fn self_type_is_available(&mut self) -> bool {
2402         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(), TypeNS, None);
2403         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2404     }
2405
2406     fn self_value_is_available(&mut self, ctxt: SyntaxContext) -> bool {
2407         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2408         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None);
2409         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2410     }
2411
2412     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2413     fn resolve_qpath_anywhere(&mut self,
2414                               id: NodeId,
2415                               qself: Option<&QSelf>,
2416                               path: &[Ident],
2417                               primary_ns: Namespace,
2418                               span: Span,
2419                               defer_to_typeck: bool,
2420                               global_by_default: bool)
2421                               -> Option<PathResolution> {
2422         let mut fin_res = None;
2423         // FIXME: can't resolve paths in macro namespace yet, macros are
2424         // processed by the little special hack below.
2425         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2426             if i == 0 || ns != primary_ns {
2427                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2428                     // If defer_to_typeck, then resolution > no resolution,
2429                     // otherwise full resolution > partial resolution > no resolution.
2430                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2431                         return Some(res),
2432                     res => if fin_res.is_none() { fin_res = res },
2433                 };
2434             }
2435         }
2436         let is_global = self.global_macros.get(&path[0].name).cloned()
2437             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2438         if primary_ns != MacroNS && (is_global || self.macro_names.contains(&path[0].name)) {
2439             // Return some dummy definition, it's enough for error reporting.
2440             return Some(
2441                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2442             );
2443         }
2444         fin_res
2445     }
2446
2447     /// Handles paths that may refer to associated items.
2448     fn resolve_qpath(&mut self,
2449                      id: NodeId,
2450                      qself: Option<&QSelf>,
2451                      path: &[Ident],
2452                      ns: Namespace,
2453                      span: Span,
2454                      global_by_default: bool)
2455                      -> Option<PathResolution> {
2456         if let Some(qself) = qself {
2457             if qself.position == 0 {
2458                 // FIXME: Create some fake resolution that can't possibly be a type.
2459                 return Some(PathResolution::with_unresolved_segments(
2460                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2461                 ));
2462             }
2463             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2464             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2465             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2466                                                        span, span, PathSource::TraitItem(ns));
2467             return Some(PathResolution::with_unresolved_segments(
2468                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2469             ));
2470         }
2471
2472         let result = match self.resolve_path(&path, Some(ns), Some(span)) {
2473             PathResult::NonModule(path_res) => path_res,
2474             PathResult::Module(module) if !module.is_normal() => {
2475                 PathResolution::new(module.def().unwrap())
2476             }
2477             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2478             // don't report an error right away, but try to fallback to a primitive type.
2479             // So, we are still able to successfully resolve something like
2480             //
2481             // use std::u8; // bring module u8 in scope
2482             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2483             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2484             //                     // not to non-existent std::u8::max_value
2485             // }
2486             //
2487             // Such behavior is required for backward compatibility.
2488             // The same fallback is used when `a` resolves to nothing.
2489             PathResult::Module(..) | PathResult::Failed(..)
2490                     if (ns == TypeNS || path.len() > 1) &&
2491                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2492                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2493                 match prim {
2494                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2495                         if !self.session.features.borrow().i128_type {
2496                             emit_feature_err(&self.session.parse_sess,
2497                                                 "i128_type", span, GateIssue::Language,
2498                                                 "128-bit type is unstable");
2499
2500                         }
2501                     }
2502                     _ => {}
2503                 }
2504                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2505             }
2506             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2507             PathResult::Failed(msg, false) => {
2508                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2509                 err_path_resolution()
2510             }
2511             PathResult::Failed(..) => return None,
2512             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2513         };
2514
2515         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2516            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2517             let unqualified_result = {
2518                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
2519                     PathResult::NonModule(path_res) => path_res.base_def(),
2520                     PathResult::Module(module) => module.def().unwrap(),
2521                     _ => return Some(result),
2522                 }
2523             };
2524             if result.base_def() == unqualified_result {
2525                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2526                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2527             }
2528         }
2529
2530         Some(result)
2531     }
2532
2533     fn resolve_path(&mut self,
2534                     path: &[Ident],
2535                     opt_ns: Option<Namespace>, // `None` indicates a module path
2536                     record_used: Option<Span>)
2537                     -> PathResult<'a> {
2538         let mut module = None;
2539         let mut allow_super = true;
2540
2541         for (i, &ident) in path.iter().enumerate() {
2542             let is_last = i == path.len() - 1;
2543             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2544
2545             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2546                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2547                 continue
2548             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2549                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2550                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2551                 if let Some(parent) = self_module.parent {
2552                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2553                     continue
2554                 } else {
2555                     let msg = "There are too many initial `super`s.".to_string();
2556                     return PathResult::Failed(msg, false);
2557                 }
2558             }
2559             allow_super = false;
2560
2561             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2562                 module = Some(self.graph_root);
2563                 continue
2564             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2565                 module = Some(self.resolve_crate_var(ident.ctxt));
2566                 continue
2567             }
2568
2569             let binding = if let Some(module) = module {
2570                 self.resolve_ident_in_module(module, ident, ns, false, record_used)
2571             } else if opt_ns == Some(MacroNS) {
2572                 self.resolve_lexical_macro_path_segment(ident, ns, record_used)
2573                     .map(MacroBinding::binding)
2574             } else {
2575                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used) {
2576                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2577                     Some(LexicalScopeBinding::Def(def))
2578                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2579                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2580                             def, path.len() - 1
2581                         ));
2582                     }
2583                     _ => Err(if record_used.is_some() { Determined } else { Undetermined }),
2584                 }
2585             };
2586
2587             match binding {
2588                 Ok(binding) => {
2589                     let def = binding.def();
2590                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2591                     if let Some(next_module) = binding.module() {
2592                         module = Some(next_module);
2593                     } else if def == Def::Err {
2594                         return PathResult::NonModule(err_path_resolution());
2595                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2596                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2597                             def, path.len() - i - 1
2598                         ));
2599                     } else {
2600                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2601                     }
2602                 }
2603                 Err(Undetermined) => return PathResult::Indeterminate,
2604                 Err(Determined) => {
2605                     if let Some(module) = module {
2606                         if opt_ns.is_some() && !module.is_normal() {
2607                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2608                                 module.def().unwrap(), path.len() - i
2609                             ));
2610                         }
2611                     }
2612                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2613                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2614                         let mut candidates =
2615                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2616                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2617                         if let Some(candidate) = candidates.get(0) {
2618                             format!("Did you mean `{}`?", candidate.path)
2619                         } else {
2620                             format!("Maybe a missing `extern crate {};`?", ident)
2621                         }
2622                     } else if i == 0 {
2623                         format!("Use of undeclared type or module `{}`", ident)
2624                     } else {
2625                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2626                     };
2627                     return PathResult::Failed(msg, is_last);
2628                 }
2629             }
2630         }
2631
2632         PathResult::Module(module.unwrap_or(self.graph_root))
2633     }
2634
2635     // Resolve a local definition, potentially adjusting for closures.
2636     fn adjust_local_def(&mut self,
2637                         ns: Namespace,
2638                         rib_index: usize,
2639                         mut def: Def,
2640                         record_used: Option<Span>) -> Def {
2641         let ribs = &self.ribs[ns][rib_index + 1..];
2642
2643         // An invalid forward use of a type parameter from a previous default.
2644         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2645             if let Some(span) = record_used {
2646                 resolve_error(self, span,
2647                         ResolutionError::ForwardDeclaredTyParam);
2648             }
2649             assert_eq!(def, Def::Err);
2650             return Def::Err;
2651         }
2652
2653         match def {
2654             Def::Upvar(..) => {
2655                 span_bug!(record_used.unwrap_or(DUMMY_SP), "unexpected {:?} in bindings", def)
2656             }
2657             Def::Local(def_id) => {
2658                 for rib in ribs {
2659                     match rib.kind {
2660                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2661                         ForwardTyParamBanRibKind => {
2662                             // Nothing to do. Continue.
2663                         }
2664                         ClosureRibKind(function_id) => {
2665                             let prev_def = def;
2666                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2667
2668                             let seen = self.freevars_seen
2669                                            .entry(function_id)
2670                                            .or_insert_with(|| NodeMap());
2671                             if let Some(&index) = seen.get(&node_id) {
2672                                 def = Def::Upvar(def_id, index, function_id);
2673                                 continue;
2674                             }
2675                             let vec = self.freevars
2676                                           .entry(function_id)
2677                                           .or_insert_with(|| vec![]);
2678                             let depth = vec.len();
2679                             def = Def::Upvar(def_id, depth, function_id);
2680
2681                             if let Some(span) = record_used {
2682                                 vec.push(Freevar {
2683                                     def: prev_def,
2684                                     span: span,
2685                                 });
2686                                 seen.insert(node_id, depth);
2687                             }
2688                         }
2689                         ItemRibKind | MethodRibKind(_) => {
2690                             // This was an attempt to access an upvar inside a
2691                             // named function item. This is not allowed, so we
2692                             // report an error.
2693                             if let Some(span) = record_used {
2694                                 resolve_error(self, span,
2695                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2696                             }
2697                             return Def::Err;
2698                         }
2699                         ConstantItemRibKind => {
2700                             // Still doesn't deal with upvars
2701                             if let Some(span) = record_used {
2702                                 resolve_error(self, span,
2703                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2704                             }
2705                             return Def::Err;
2706                         }
2707                     }
2708                 }
2709             }
2710             Def::TyParam(..) | Def::SelfTy(..) => {
2711                 for rib in ribs {
2712                     match rib.kind {
2713                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2714                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind => {
2715                             // Nothing to do. Continue.
2716                         }
2717                         ItemRibKind => {
2718                             // This was an attempt to use a type parameter outside
2719                             // its scope.
2720                             if let Some(span) = record_used {
2721                                 resolve_error(self, span,
2722                                               ResolutionError::TypeParametersFromOuterFunction);
2723                             }
2724                             return Def::Err;
2725                         }
2726                         ConstantItemRibKind => {
2727                             // see #9186
2728                             if let Some(span) = record_used {
2729                                 resolve_error(self, span,
2730                                               ResolutionError::OuterTypeParameterContext);
2731                             }
2732                             return Def::Err;
2733                         }
2734                     }
2735                 }
2736             }
2737             _ => {}
2738         }
2739         return def;
2740     }
2741
2742     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2743     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2744     // FIXME #34673: This needs testing.
2745     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2746         where F: FnOnce(&mut Resolver<'a>) -> T,
2747     {
2748         self.with_empty_ribs(|this| {
2749             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2750             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2751             f(this)
2752         })
2753     }
2754
2755     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2756         where F: FnOnce(&mut Resolver<'a>) -> T,
2757     {
2758         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2759         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2760
2761         let result = f(self);
2762         self.ribs = ribs;
2763         self.label_ribs = label_ribs;
2764         result
2765     }
2766
2767     fn lookup_assoc_candidate<FilterFn>(&mut self,
2768                                         name: Name,
2769                                         ns: Namespace,
2770                                         filter_fn: FilterFn)
2771                                         -> Option<AssocSuggestion>
2772         where FilterFn: Fn(Def) -> bool
2773     {
2774         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2775             match t.node {
2776                 TyKind::Path(None, _) => Some(t.id),
2777                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2778                 // This doesn't handle the remaining `Ty` variants as they are not
2779                 // that commonly the self_type, it might be interesting to provide
2780                 // support for those in future.
2781                 _ => None,
2782             }
2783         }
2784
2785         // Fields are generally expected in the same contexts as locals.
2786         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2787             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2788                 // Look for a field with the same name in the current self_type.
2789                 if let Some(resolution) = self.def_map.get(&node_id) {
2790                     match resolution.base_def() {
2791                         Def::Struct(did) | Def::Union(did)
2792                                 if resolution.unresolved_segments() == 0 => {
2793                             if let Some(field_names) = self.field_names.get(&did) {
2794                                 if field_names.iter().any(|&field_name| name == field_name) {
2795                                     return Some(AssocSuggestion::Field);
2796                                 }
2797                             }
2798                         }
2799                         _ => {}
2800                     }
2801                 }
2802             }
2803         }
2804
2805         // Look for associated items in the current trait.
2806         if let Some((trait_did, _)) = self.current_trait_ref {
2807             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2808                 if filter_fn(def) {
2809                     return Some(if has_self {
2810                         AssocSuggestion::MethodWithSelf
2811                     } else {
2812                         AssocSuggestion::AssocItem
2813                     });
2814                 }
2815             }
2816         }
2817
2818         None
2819     }
2820
2821     fn lookup_typo_candidate<FilterFn>(&mut self,
2822                                        path: &[Ident],
2823                                        ns: Namespace,
2824                                        filter_fn: FilterFn)
2825                                        -> Option<Symbol>
2826         where FilterFn: Fn(Def) -> bool
2827     {
2828         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2829             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2830                 if let Some(binding) = resolution.borrow().binding {
2831                     if filter_fn(binding.def()) {
2832                         names.push(ident.name);
2833                     }
2834                 }
2835             }
2836         };
2837
2838         let mut names = Vec::new();
2839         if path.len() == 1 {
2840             // Search in lexical scope.
2841             // Walk backwards up the ribs in scope and collect candidates.
2842             for rib in self.ribs[ns].iter().rev() {
2843                 // Locals and type parameters
2844                 for (ident, def) in &rib.bindings {
2845                     if filter_fn(*def) {
2846                         names.push(ident.name);
2847                     }
2848                 }
2849                 // Items in scope
2850                 if let ModuleRibKind(module) = rib.kind {
2851                     // Items from this module
2852                     add_module_candidates(module, &mut names);
2853
2854                     if let ModuleKind::Block(..) = module.kind {
2855                         // We can see through blocks
2856                     } else {
2857                         // Items from the prelude
2858                         if let Some(prelude) = self.prelude {
2859                             if !module.no_implicit_prelude {
2860                                 add_module_candidates(prelude, &mut names);
2861                             }
2862                         }
2863                         break;
2864                     }
2865                 }
2866             }
2867             // Add primitive types to the mix
2868             if filter_fn(Def::PrimTy(TyBool)) {
2869                 for (name, _) in &self.primitive_type_table.primitive_types {
2870                     names.push(*name);
2871                 }
2872             }
2873         } else {
2874             // Search in module.
2875             let mod_path = &path[..path.len() - 1];
2876             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS), None) {
2877                 add_module_candidates(module, &mut names);
2878             }
2879         }
2880
2881         let name = path[path.len() - 1].name;
2882         // Make sure error reporting is deterministic.
2883         names.sort_by_key(|name| name.as_str());
2884         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2885             Some(found) if found != name => Some(found),
2886             _ => None,
2887         }
2888     }
2889
2890     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2891         where F: FnOnce(&mut Resolver)
2892     {
2893         if let Some(label) = label {
2894             let def = Def::Label(id);
2895             self.with_label_rib(|this| {
2896                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2897                 f(this);
2898             });
2899         } else {
2900             f(self);
2901         }
2902     }
2903
2904     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2905         self.with_resolved_label(label, id, |this| this.visit_block(block));
2906     }
2907
2908     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2909         // First, record candidate traits for this expression if it could
2910         // result in the invocation of a method call.
2911
2912         self.record_candidate_traits_for_expr_if_necessary(expr);
2913
2914         // Next, resolve the node.
2915         match expr.node {
2916             ExprKind::Path(ref qself, ref path) => {
2917                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2918                 visit::walk_expr(self, expr);
2919             }
2920
2921             ExprKind::Struct(ref path, ..) => {
2922                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2923                 visit::walk_expr(self, expr);
2924             }
2925
2926             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2927                 match self.search_label(label.node) {
2928                     None => {
2929                         self.record_def(expr.id, err_path_resolution());
2930                         resolve_error(self,
2931                                       label.span,
2932                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2933                     }
2934                     Some(def @ Def::Label(_)) => {
2935                         // Since this def is a label, it is never read.
2936                         self.record_def(expr.id, PathResolution::new(def));
2937                     }
2938                     Some(_) => {
2939                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2940                     }
2941                 }
2942
2943                 // visit `break` argument if any
2944                 visit::walk_expr(self, expr);
2945             }
2946
2947             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2948                 self.visit_expr(subexpression);
2949
2950                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2951                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
2952                 self.visit_block(if_block);
2953                 self.ribs[ValueNS].pop();
2954
2955                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
2956             }
2957
2958             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2959
2960             ExprKind::While(ref subexpression, ref block, label) => {
2961                 self.with_resolved_label(label, expr.id, |this| {
2962                     this.visit_expr(subexpression);
2963                     this.visit_block(block);
2964                 });
2965             }
2966
2967             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
2968                 self.with_resolved_label(label, expr.id, |this| {
2969                     this.visit_expr(subexpression);
2970                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
2971                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
2972                     this.visit_block(block);
2973                     this.ribs[ValueNS].pop();
2974                 });
2975             }
2976
2977             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
2978                 self.visit_expr(subexpression);
2979                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2980                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
2981
2982                 self.resolve_labeled_block(label, expr.id, block);
2983
2984                 self.ribs[ValueNS].pop();
2985             }
2986
2987             // Equivalent to `visit::walk_expr` + passing some context to children.
2988             ExprKind::Field(ref subexpression, _) => {
2989                 self.resolve_expr(subexpression, Some(expr));
2990             }
2991             ExprKind::MethodCall(_, ref types, ref arguments) => {
2992                 let mut arguments = arguments.iter();
2993                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2994                 for argument in arguments {
2995                     self.resolve_expr(argument, None);
2996                 }
2997                 for ty in types.iter() {
2998                     self.visit_ty(ty);
2999                 }
3000             }
3001
3002             ExprKind::Repeat(ref element, ref count) => {
3003                 self.visit_expr(element);
3004                 self.with_constant_rib(|this| {
3005                     this.visit_expr(count);
3006                 });
3007             }
3008             ExprKind::Call(ref callee, ref arguments) => {
3009                 self.resolve_expr(callee, Some(expr));
3010                 for argument in arguments {
3011                     self.resolve_expr(argument, None);
3012                 }
3013             }
3014
3015             _ => {
3016                 visit::walk_expr(self, expr);
3017             }
3018         }
3019     }
3020
3021     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3022         match expr.node {
3023             ExprKind::Field(_, name) => {
3024                 // FIXME(#6890): Even though you can't treat a method like a
3025                 // field, we need to add any trait methods we find that match
3026                 // the field name so that we can do some nice error reporting
3027                 // later on in typeck.
3028                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3029                 self.trait_map.insert(expr.id, traits);
3030             }
3031             ExprKind::MethodCall(name, ..) => {
3032                 debug!("(recording candidate traits for expr) recording traits for {}",
3033                        expr.id);
3034                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3035                 self.trait_map.insert(expr.id, traits);
3036             }
3037             _ => {
3038                 // Nothing to do.
3039             }
3040         }
3041     }
3042
3043     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3044         debug!("(getting traits containing item) looking for '{}'", name);
3045
3046         let mut found_traits = Vec::new();
3047         // Look for the current trait.
3048         if let Some((trait_def_id, _)) = self.current_trait_ref {
3049             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3050                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3051             }
3052         }
3053
3054         let mut search_module = self.current_module;
3055         loop {
3056             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3057             match search_module.kind {
3058                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3059                 _ => break,
3060             }
3061         }
3062
3063         if let Some(prelude) = self.prelude {
3064             if !search_module.no_implicit_prelude {
3065                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3066             }
3067         }
3068
3069         found_traits
3070     }
3071
3072     fn get_traits_in_module_containing_item(&mut self,
3073                                             name: Name,
3074                                             ns: Namespace,
3075                                             module: Module,
3076                                             found_traits: &mut Vec<TraitCandidate>) {
3077         let mut traits = module.traits.borrow_mut();
3078         if traits.is_none() {
3079             let mut collected_traits = Vec::new();
3080             module.for_each_child(|name, ns, binding| {
3081                 if ns != TypeNS { return }
3082                 if let Def::Trait(_) = binding.def() {
3083                     collected_traits.push((name, binding));
3084                 }
3085             });
3086             *traits = Some(collected_traits.into_boxed_slice());
3087         }
3088
3089         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3090             let trait_def_id = binding.def().def_id();
3091             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3092                 let import_id = match binding.kind {
3093                     NameBindingKind::Import { directive, .. } => {
3094                         self.maybe_unused_trait_imports.insert(directive.id);
3095                         self.add_to_glob_map(directive.id, trait_name);
3096                         Some(directive.id)
3097                     }
3098                     _ => None,
3099                 };
3100                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3101             }
3102         }
3103     }
3104
3105     /// When name resolution fails, this method can be used to look up candidate
3106     /// entities with the expected name. It allows filtering them using the
3107     /// supplied predicate (which should be used to only accept the types of
3108     /// definitions expected e.g. traits). The lookup spans across all crates.
3109     ///
3110     /// NOTE: The method does not look into imports, but this is not a problem,
3111     /// since we report the definitions (thus, the de-aliased imports).
3112     fn lookup_import_candidates<FilterFn>(&mut self,
3113                                           lookup_name: Name,
3114                                           namespace: Namespace,
3115                                           filter_fn: FilterFn)
3116                                           -> Vec<ImportSuggestion>
3117         where FilterFn: Fn(Def) -> bool
3118     {
3119         let mut candidates = Vec::new();
3120         let mut worklist = Vec::new();
3121         let mut seen_modules = FxHashSet();
3122         worklist.push((self.graph_root, Vec::new(), false));
3123
3124         while let Some((in_module,
3125                         path_segments,
3126                         in_module_is_extern)) = worklist.pop() {
3127             self.populate_module_if_necessary(in_module);
3128
3129             in_module.for_each_child(|ident, ns, name_binding| {
3130
3131                 // avoid imports entirely
3132                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3133                 // avoid non-importable candidates as well
3134                 if !name_binding.is_importable() { return; }
3135
3136                 // collect results based on the filter function
3137                 if ident.name == lookup_name && ns == namespace {
3138                     if filter_fn(name_binding.def()) {
3139                         // create the path
3140                         let mut segms = path_segments.clone();
3141                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3142                         let path = Path {
3143                             span: name_binding.span,
3144                             segments: segms,
3145                         };
3146                         // the entity is accessible in the following cases:
3147                         // 1. if it's defined in the same crate, it's always
3148                         // accessible (since private entities can be made public)
3149                         // 2. if it's defined in another crate, it's accessible
3150                         // only if both the module is public and the entity is
3151                         // declared as public (due to pruning, we don't explore
3152                         // outside crate private modules => no need to check this)
3153                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3154                             candidates.push(ImportSuggestion { path: path });
3155                         }
3156                     }
3157                 }
3158
3159                 // collect submodules to explore
3160                 if let Some(module) = name_binding.module() {
3161                     // form the path
3162                     let mut path_segments = path_segments.clone();
3163                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3164
3165                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3166                         // add the module to the lookup
3167                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3168                         if seen_modules.insert(module.def_id().unwrap()) {
3169                             worklist.push((module, path_segments, is_extern));
3170                         }
3171                     }
3172                 }
3173             })
3174         }
3175
3176         candidates
3177     }
3178
3179     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3180         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3181         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3182             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3183         }
3184     }
3185
3186     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3187         match *vis {
3188             ast::Visibility::Public => ty::Visibility::Public,
3189             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3190             ast::Visibility::Inherited => {
3191                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3192             }
3193             ast::Visibility::Restricted { ref path, id } => {
3194                 let def = self.smart_resolve_path(id, None, path,
3195                                                   PathSource::Visibility).base_def();
3196                 if def == Def::Err {
3197                     ty::Visibility::Public
3198                 } else {
3199                     let vis = ty::Visibility::Restricted(def.def_id());
3200                     if self.is_accessible(vis) {
3201                         vis
3202                     } else {
3203                         self.session.span_err(path.span, "visibilities can only be restricted \
3204                                                           to ancestor modules");
3205                         ty::Visibility::Public
3206                     }
3207                 }
3208             }
3209         }
3210     }
3211
3212     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3213         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3214     }
3215
3216     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3217         vis.is_accessible_from(module.normal_ancestor_id, self)
3218     }
3219
3220     fn report_errors(&mut self) {
3221         self.report_shadowing_errors();
3222         let mut reported_spans = FxHashSet();
3223
3224         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3225             if !reported_spans.insert(span) { continue }
3226             let participle = |binding: &NameBinding| {
3227                 if binding.is_import() { "imported" } else { "defined" }
3228             };
3229             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3230             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3231             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3232                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3233             } else if let Def::Macro(..) = b1.def() {
3234                 format!("macro-expanded {} do not shadow",
3235                         if b1.is_import() { "macro imports" } else { "macros" })
3236             } else {
3237                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3238                         if b1.is_import() { "imports" } else { "items" })
3239             };
3240             if legacy {
3241                 let id = match b2.kind {
3242                     NameBindingKind::Import { directive, .. } => directive.id,
3243                     _ => unreachable!(),
3244                 };
3245                 let mut span = MultiSpan::from_span(span);
3246                 span.push_span_label(b1.span, msg1);
3247                 span.push_span_label(b2.span, msg2);
3248                 let msg = format!("`{}` is ambiguous", name);
3249                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3250             } else {
3251                 let mut err =
3252                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3253                 err.span_note(b1.span, &msg1);
3254                 match b2.def() {
3255                     Def::Macro(..) if b2.span == DUMMY_SP =>
3256                         err.note(&format!("`{}` is also a builtin macro", name)),
3257                     _ => err.span_note(b2.span, &msg2),
3258                 };
3259                 err.note(&note).emit();
3260             }
3261         }
3262
3263         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3264             if !reported_spans.insert(span) { continue }
3265             if binding.is_extern_crate() {
3266                 // Warn when using an inaccessible extern crate.
3267                 let node_id = match binding.kind {
3268                     NameBindingKind::Import { directive, .. } => directive.id,
3269                     _ => unreachable!(),
3270                 };
3271                 let msg = format!("extern crate `{}` is private", name);
3272                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3273             } else {
3274                 let def = binding.def();
3275                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3276             }
3277         }
3278     }
3279
3280     fn report_shadowing_errors(&mut self) {
3281         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3282             self.resolve_legacy_scope(scope, name, true);
3283         }
3284
3285         let mut reported_errors = FxHashSet();
3286         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3287             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3288                reported_errors.insert((binding.name, binding.span)) {
3289                 let msg = format!("`{}` is already in scope", binding.name);
3290                 self.session.struct_span_err(binding.span, &msg)
3291                     .note("macro-expanded `macro_rules!`s may not shadow \
3292                            existing macros (see RFC 1560)")
3293                     .emit();
3294             }
3295         }
3296     }
3297
3298     fn report_conflict(&mut self,
3299                        parent: Module,
3300                        ident: Ident,
3301                        ns: Namespace,
3302                        binding: &NameBinding,
3303                        old_binding: &NameBinding) {
3304         // Error on the second of two conflicting names
3305         if old_binding.span.lo > binding.span.lo {
3306             return self.report_conflict(parent, ident, ns, old_binding, binding);
3307         }
3308
3309         let container = match parent.kind {
3310             ModuleKind::Def(Def::Mod(_), _) => "module",
3311             ModuleKind::Def(Def::Trait(_), _) => "trait",
3312             ModuleKind::Block(..) => "block",
3313             _ => "enum",
3314         };
3315
3316         let (participle, noun) = match old_binding.is_import() {
3317             true => ("imported", "import"),
3318             false => ("defined", "definition"),
3319         };
3320
3321         let (name, span) = (ident.name, binding.span);
3322
3323         if let Some(s) = self.name_already_seen.get(&name) {
3324             if s == &span {
3325                 return;
3326             }
3327         }
3328
3329         let msg = {
3330             let kind = match (ns, old_binding.module()) {
3331                 (ValueNS, _) => "a value",
3332                 (MacroNS, _) => "a macro",
3333                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3334                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3335                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3336                 (TypeNS, _) => "a type",
3337             };
3338             format!("{} named `{}` has already been {} in this {}",
3339                     kind, name, participle, container)
3340         };
3341
3342         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3343             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3344             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3345                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3346                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3347             },
3348             _ => match (old_binding.is_import(), binding.is_import()) {
3349                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3350                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3351                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3352             },
3353         };
3354
3355         err.span_label(span, &format!("`{}` already {}", name, participle));
3356         if old_binding.span != syntax_pos::DUMMY_SP {
3357             err.span_label(old_binding.span, &format!("previous {} of `{}` here", noun, name));
3358         }
3359         err.emit();
3360         self.name_already_seen.insert(name, span);
3361     }
3362
3363     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3364         let (id, span) = (directive.id, directive.span);
3365         let msg = "`self` no longer imports values".to_string();
3366         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3367     }
3368
3369     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3370         if self.proc_macro_enabled { return; }
3371
3372         for attr in attrs {
3373             if attr.path.segments.len() > 1 {
3374                 continue
3375             }
3376             let ident = attr.path.segments[0].identifier;
3377             let result = self.resolve_lexical_macro_path_segment(ident, MacroNS, None);
3378             if let Ok(binding) = result {
3379                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3380                     attr::mark_known(attr);
3381
3382                     let msg = "attribute procedural macros are experimental";
3383                     let feature = "proc_macro";
3384
3385                     feature_err(&self.session.parse_sess, feature,
3386                                 attr.span, GateIssue::Language, msg)
3387                         .span_note(binding.span(), "procedural macro imported here")
3388                         .emit();
3389                 }
3390             }
3391         }
3392     }
3393 }
3394
3395 fn is_struct_like(def: Def) -> bool {
3396     match def {
3397         Def::VariantCtor(_, CtorKind::Fictive) => true,
3398         _ => PathSource::Struct.is_expected(def),
3399     }
3400 }
3401
3402 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3403     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3404 }
3405
3406 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3407     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3408 }
3409
3410 fn names_to_string(idents: &[Ident]) -> String {
3411     let mut result = String::new();
3412     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3413         if i > 0 {
3414             result.push_str("::");
3415         }
3416         result.push_str(&ident.name.as_str());
3417     }
3418     result
3419 }
3420
3421 fn path_names_to_string(path: &Path) -> String {
3422     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3423 }
3424
3425 /// When an entity with a given name is not available in scope, we search for
3426 /// entities with that name in all crates. This method allows outputting the
3427 /// results of this search in a programmer-friendly way
3428 fn show_candidates(session: &mut DiagnosticBuilder,
3429                    candidates: &[ImportSuggestion],
3430                    better: bool) {
3431     // don't show more than MAX_CANDIDATES results, so
3432     // we're consistent with the trait suggestions
3433     const MAX_CANDIDATES: usize = 4;
3434
3435     // we want consistent results across executions, but candidates are produced
3436     // by iterating through a hash map, so make sure they are ordered:
3437     let mut path_strings: Vec<_> =
3438         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3439     path_strings.sort();
3440
3441     let better = if better { "better " } else { "" };
3442     let msg_diff = match path_strings.len() {
3443         1 => " is found in another module, you can import it",
3444         _ => "s are found in other modules, you can import them",
3445     };
3446
3447     let end = cmp::min(MAX_CANDIDATES, path_strings.len());
3448     session.help(&format!("possible {}candidate{} into scope:{}{}",
3449                           better,
3450                           msg_diff,
3451                           &path_strings[0..end].iter().map(|candidate| {
3452                               format!("\n  `use {};`", candidate)
3453                           }).collect::<String>(),
3454                           if path_strings.len() > MAX_CANDIDATES {
3455                               format!("\nand {} other candidates",
3456                                       path_strings.len() - MAX_CANDIDATES)
3457                           } else {
3458                               "".to_owned()
3459                           }
3460                           ));
3461 }
3462
3463 /// A somewhat inefficient routine to obtain the name of a module.
3464 fn module_to_string(module: Module) -> String {
3465     let mut names = Vec::new();
3466
3467     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3468         if let ModuleKind::Def(_, name) = module.kind {
3469             if let Some(parent) = module.parent {
3470                 names.push(Ident::with_empty_ctxt(name));
3471                 collect_mod(names, parent);
3472             }
3473         } else {
3474             // danger, shouldn't be ident?
3475             names.push(Ident::from_str("<opaque>"));
3476             collect_mod(names, module.parent.unwrap());
3477         }
3478     }
3479     collect_mod(&mut names, module);
3480
3481     if names.is_empty() {
3482         return "???".to_string();
3483     }
3484     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3485 }
3486
3487 fn err_path_resolution() -> PathResolution {
3488     PathResolution::new(Def::Err)
3489 }
3490
3491 #[derive(PartialEq,Copy, Clone)]
3492 pub enum MakeGlobMap {
3493     Yes,
3494     No,
3495 }
3496
3497 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }