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};
  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
 927 impl<'a> fmt::Debug for ModuleData<'a> {
 928     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 929         write!(f, "{:?}", self.def())
 930     }
 931 }
 932
 933 // Records a possibly-private value, type, or module definition.
 934 #[derive(Clone, Debug)]
 935 pub struct NameBinding<'a> {
 936     kind: NameBindingKind<'a>,
 937     expansion: Mark,
 938     span: Span,
 939     vis: ty::Visibility,
 940 }
 941
 942 pub trait ToNameBinding<'a> {
 943     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 944 }
 945
 946 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 947     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 948         self
 949     }
 950 }
 951
 952 #[derive(Clone, Debug)]
 953 enum NameBindingKind<'a> {
 954     Def(Def),
 955     Module(Module<'a>),
 956     Import {
 957         binding: &'a NameBinding<'a>,
 958         directive: &'a ImportDirective<'a>,
 959         used: Cell<bool>,
 960         legacy_self_import: bool,
 961     },
 962     Ambiguity {
 963         b1: &'a NameBinding<'a>,
 964         b2: &'a NameBinding<'a>,
 965         legacy: bool,
 966     }
 967 }
 968
 969 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 970
 971 struct AmbiguityError<'a> {
 972     span: Span,
 973     name: Name,
 974     lexical: bool,
 975     b1: &'a NameBinding<'a>,
 976     b2: &'a NameBinding<'a>,
 977     legacy: bool,
 978 }
 979
 980 impl<'a> NameBinding<'a> {
 981     fn module(&self) -> Option<Module<'a>> {
 982         match self.kind {
 983             NameBindingKind::Module(module) => Some(module),
 984             NameBindingKind::Import { binding, .. } => binding.module(),
 985             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 986             _ => None,
 987         }
 988     }
 989
 990     fn def(&self) -> Def {
 991         match self.kind {
 992             NameBindingKind::Def(def) => def,
 993             NameBindingKind::Module(module) => module.def().unwrap(),
 994             NameBindingKind::Import { binding, .. } => binding.def(),
 995             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
 996             NameBindingKind::Ambiguity { .. } => Def::Err,
 997         }
 998     }
 999
1000     fn def_ignoring_ambiguity(&self) -> Def {
1001         match self.kind {
1002             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1003             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1004             _ => self.def(),
1005         }
1006     }
1007
1008     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1009         resolver.get_macro(self.def_ignoring_ambiguity())
1010     }
1011
1012     // We sometimes need to treat variants as `pub` for backwards compatibility
1013     fn pseudo_vis(&self) -> ty::Visibility {
1014         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1015     }
1016
1017     fn is_variant(&self) -> bool {
1018         match self.kind {
1019             NameBindingKind::Def(Def::Variant(..)) |
1020             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1021             _ => false,
1022         }
1023     }
1024
1025     fn is_extern_crate(&self) -> bool {
1026         match self.kind {
1027             NameBindingKind::Import {
1028                 directive: &ImportDirective {
1029                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1030                 }, ..
1031             } => true,
1032             _ => false,
1033         }
1034     }
1035
1036     fn is_import(&self) -> bool {
1037         match self.kind {
1038             NameBindingKind::Import { .. } => true,
1039             _ => false,
1040         }
1041     }
1042
1043     fn is_glob_import(&self) -> bool {
1044         match self.kind {
1045             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1046             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1047             _ => false,
1048         }
1049     }
1050
1051     fn is_importable(&self) -> bool {
1052         match self.def() {
1053             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1054             _ => true,
1055         }
1056     }
1057 }
1058
1059 /// Interns the names of the primitive types.
1060 struct PrimitiveTypeTable {
1061     primitive_types: FxHashMap<Name, PrimTy>,
1062 }
1063
1064 impl PrimitiveTypeTable {
1065     fn new() -> PrimitiveTypeTable {
1066         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1067
1068         table.intern("bool", TyBool);
1069         table.intern("char", TyChar);
1070         table.intern("f32", TyFloat(FloatTy::F32));
1071         table.intern("f64", TyFloat(FloatTy::F64));
1072         table.intern("isize", TyInt(IntTy::Is));
1073         table.intern("i8", TyInt(IntTy::I8));
1074         table.intern("i16", TyInt(IntTy::I16));
1075         table.intern("i32", TyInt(IntTy::I32));
1076         table.intern("i64", TyInt(IntTy::I64));
1077         table.intern("i128", TyInt(IntTy::I128));
1078         table.intern("str", TyStr);
1079         table.intern("usize", TyUint(UintTy::Us));
1080         table.intern("u8", TyUint(UintTy::U8));
1081         table.intern("u16", TyUint(UintTy::U16));
1082         table.intern("u32", TyUint(UintTy::U32));
1083         table.intern("u64", TyUint(UintTy::U64));
1084         table.intern("u128", TyUint(UintTy::U128));
1085         table
1086     }
1087
1088     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1089         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1090     }
1091 }
1092
1093 /// The main resolver class.
1094 pub struct Resolver<'a> {
1095     session: &'a Session,
1096
1097     pub definitions: Definitions,
1098
1099     graph_root: Module<'a>,
1100
1101     prelude: Option<Module<'a>>,
1102
1103     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1104
1105     // Names of fields of an item `DefId` accessible with dot syntax.
1106     // Used for hints during error reporting.
1107     field_names: FxHashMap<DefId, Vec<Name>>,
1108
1109     // All imports known to succeed or fail.
1110     determined_imports: Vec<&'a ImportDirective<'a>>,
1111
1112     // All non-determined imports.
1113     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1114
1115     // The module that represents the current item scope.
1116     current_module: Module<'a>,
1117
1118     // The current set of local scopes for types and values.
1119     // FIXME #4948: Reuse ribs to avoid allocation.
1120     ribs: PerNS<Vec<Rib<'a>>>,
1121
1122     // The current set of local scopes, for labels.
1123     label_ribs: Vec<Rib<'a>>,
1124
1125     // The trait that the current context can refer to.
1126     current_trait_ref: Option<(DefId, TraitRef)>,
1127
1128     // The current self type if inside an impl (used for better errors).
1129     current_self_type: Option<Ty>,
1130
1131     // The idents for the primitive types.
1132     primitive_type_table: PrimitiveTypeTable,
1133
1134     def_map: DefMap,
1135     pub freevars: FreevarMap,
1136     freevars_seen: NodeMap<NodeMap<usize>>,
1137     pub export_map: ExportMap,
1138     pub trait_map: TraitMap,
1139
1140     // A map from nodes to anonymous modules.
1141     // Anonymous modules are pseudo-modules that are implicitly created around items
1142     // contained within blocks.
1143     //
1144     // For example, if we have this:
1145     //
1146     //  fn f() {
1147     //      fn g() {
1148     //          ...
1149     //      }
1150     //  }
1151     //
1152     // There will be an anonymous module created around `g` with the ID of the
1153     // entry block for `f`.
1154     block_map: NodeMap<Module<'a>>,
1155     module_map: FxHashMap<DefId, Module<'a>>,
1156     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1157
1158     pub make_glob_map: bool,
1159     // Maps imports to the names of items actually imported (this actually maps
1160     // all imports, but only glob imports are actually interesting).
1161     pub glob_map: GlobMap,
1162
1163     used_imports: FxHashSet<(NodeId, Namespace)>,
1164     pub maybe_unused_trait_imports: NodeSet,
1165
1166     privacy_errors: Vec<PrivacyError<'a>>,
1167     ambiguity_errors: Vec<AmbiguityError<'a>>,
1168     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1169
1170     arenas: &'a ResolverArenas<'a>,
1171     dummy_binding: &'a NameBinding<'a>,
1172     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1173
1174     crate_loader: &'a mut CrateLoader,
1175     macro_names: FxHashSet<Name>,
1176     builtin_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1177     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1178     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1179     macro_defs: FxHashMap<Mark, DefId>,
1180     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1181     macro_exports: Vec<Export>,
1182     pub whitelisted_legacy_custom_derives: Vec<Name>,
1183     pub found_unresolved_macro: bool,
1184
1185     // Maps the `Mark` of an expansion to its containing module or block.
1186     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1187
1188     // Avoid duplicated errors for "name already defined".
1189     name_already_seen: FxHashMap<Name, Span>,
1190
1191     // If `#![feature(proc_macro)]` is set
1192     proc_macro_enabled: bool,
1193
1194     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1195     warned_proc_macros: FxHashSet<Name>,
1196
1197     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1198
1199     // This table maps struct IDs into struct constructor IDs,
1200     // it's not used during normal resolution, only for better error reporting.
1201     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1202 }
1203
1204 pub struct ResolverArenas<'a> {
1205     modules: arena::TypedArena<ModuleData<'a>>,
1206     local_modules: RefCell<Vec<Module<'a>>>,
1207     name_bindings: arena::TypedArena<NameBinding<'a>>,
1208     import_directives: arena::TypedArena<ImportDirective<'a>>,
1209     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1210     invocation_data: arena::TypedArena<InvocationData<'a>>,
1211     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1212 }
1213
1214 impl<'a> ResolverArenas<'a> {
1215     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1216         let module = self.modules.alloc(module);
1217         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1218             self.local_modules.borrow_mut().push(module);
1219         }
1220         module
1221     }
1222     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1223         self.local_modules.borrow()
1224     }
1225     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1226         self.name_bindings.alloc(name_binding)
1227     }
1228     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1229                               -> &'a ImportDirective {
1230         self.import_directives.alloc(import_directive)
1231     }
1232     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1233         self.name_resolutions.alloc(Default::default())
1234     }
1235     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1236                              -> &'a InvocationData<'a> {
1237         self.invocation_data.alloc(expansion_data)
1238     }
1239     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1240         self.legacy_bindings.alloc(binding)
1241     }
1242 }
1243
1244 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1245     fn parent(self, id: DefId) -> Option<DefId> {
1246         match id.krate {
1247             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1248             _ => self.session.cstore.def_key(id).parent,
1249         }.map(|index| DefId { index: index, ..id })
1250     }
1251 }
1252
1253 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1254     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1255         let namespace = if is_value { ValueNS } else { TypeNS };
1256         let hir::Path { ref segments, span, ref mut def } = *path;
1257         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1258         match self.resolve_path(&path, Some(namespace), Some(span)) {
1259             PathResult::Module(module) => *def = module.def().unwrap(),
1260             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1261                 *def = path_res.base_def(),
1262             PathResult::NonModule(..) => match self.resolve_path(&path, None, Some(span)) {
1263                 PathResult::Failed(msg, _) => {
1264                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1265                 }
1266                 _ => {}
1267             },
1268             PathResult::Indeterminate => unreachable!(),
1269             PathResult::Failed(msg, _) => {
1270                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1271             }
1272         }
1273     }
1274
1275     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1276         self.def_map.get(&id).cloned()
1277     }
1278
1279     fn definitions(&mut self) -> &mut Definitions {
1280         &mut self.definitions
1281     }
1282 }
1283
1284 impl<'a> Resolver<'a> {
1285     pub fn new(session: &'a Session,
1286                krate: &Crate,
1287                make_glob_map: MakeGlobMap,
1288                crate_loader: &'a mut CrateLoader,
1289                arenas: &'a ResolverArenas<'a>)
1290                -> Resolver<'a> {
1291         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1292         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1293         let graph_root = arenas.alloc_module(ModuleData {
1294             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1295             ..ModuleData::new(None, root_module_kind, root_def_id)
1296         });
1297         let mut module_map = FxHashMap();
1298         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1299
1300         let mut definitions = Definitions::new();
1301         DefCollector::new(&mut definitions).collect_root();
1302
1303         let mut invocations = FxHashMap();
1304         invocations.insert(Mark::root(),
1305                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1306
1307         let features = session.features.borrow();
1308
1309         let mut macro_defs = FxHashMap();
1310         macro_defs.insert(Mark::root(), root_def_id);
1311
1312         Resolver {
1313             session: session,
1314
1315             definitions: definitions,
1316
1317             // The outermost module has def ID 0; this is not reflected in the
1318             // AST.
1319             graph_root: graph_root,
1320             prelude: None,
1321
1322             trait_item_map: FxHashMap(),
1323             field_names: FxHashMap(),
1324
1325             determined_imports: Vec::new(),
1326             indeterminate_imports: Vec::new(),
1327
1328             current_module: graph_root,
1329             ribs: PerNS {
1330                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1331                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1332                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1333             },
1334             label_ribs: Vec::new(),
1335
1336             current_trait_ref: None,
1337             current_self_type: None,
1338
1339             primitive_type_table: PrimitiveTypeTable::new(),
1340
1341             def_map: NodeMap(),
1342             freevars: NodeMap(),
1343             freevars_seen: NodeMap(),
1344             export_map: NodeMap(),
1345             trait_map: NodeMap(),
1346             module_map: module_map,
1347             block_map: NodeMap(),
1348             extern_crate_roots: FxHashMap(),
1349
1350             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1351             glob_map: NodeMap(),
1352
1353             used_imports: FxHashSet(),
1354             maybe_unused_trait_imports: NodeSet(),
1355
1356             privacy_errors: Vec::new(),
1357             ambiguity_errors: Vec::new(),
1358             disallowed_shadowing: Vec::new(),
1359
1360             arenas: arenas,
1361             dummy_binding: arenas.alloc_name_binding(NameBinding {
1362                 kind: NameBindingKind::Def(Def::Err),
1363                 expansion: Mark::root(),
1364                 span: DUMMY_SP,
1365                 vis: ty::Visibility::Public,
1366             }),
1367
1368             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1369             use_extern_macros: features.use_extern_macros || features.proc_macro,
1370
1371             crate_loader: crate_loader,
1372             macro_names: FxHashSet(),
1373             builtin_macros: FxHashMap(),
1374             lexical_macro_resolutions: Vec::new(),
1375             macro_map: FxHashMap(),
1376             macro_exports: Vec::new(),
1377             invocations: invocations,
1378             macro_defs: macro_defs,
1379             local_macro_def_scopes: FxHashMap(),
1380             name_already_seen: FxHashMap(),
1381             whitelisted_legacy_custom_derives: Vec::new(),
1382             proc_macro_enabled: features.proc_macro,
1383             warned_proc_macros: FxHashSet(),
1384             potentially_unused_imports: Vec::new(),
1385             struct_constructors: DefIdMap(),
1386             found_unresolved_macro: false,
1387         }
1388     }
1389
1390     pub fn arenas() -> ResolverArenas<'a> {
1391         ResolverArenas {
1392             modules: arena::TypedArena::new(),
1393             local_modules: RefCell::new(Vec::new()),
1394             name_bindings: arena::TypedArena::new(),
1395             import_directives: arena::TypedArena::new(),
1396             name_resolutions: arena::TypedArena::new(),
1397             invocation_data: arena::TypedArena::new(),
1398             legacy_bindings: arena::TypedArena::new(),
1399         }
1400     }
1401
1402     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1403         PerNS {
1404             type_ns: f(self, TypeNS),
1405             value_ns: f(self, ValueNS),
1406             macro_ns: match self.use_extern_macros {
1407                 true => Some(f(self, MacroNS)),
1408                 false => None,
1409             },
1410         }
1411     }
1412
1413     /// Entry point to crate resolution.
1414     pub fn resolve_crate(&mut self, krate: &Crate) {
1415         ImportResolver { resolver: self }.finalize_imports();
1416         self.current_module = self.graph_root;
1417         self.finalize_current_module_macro_resolutions();
1418         visit::walk_crate(self, krate);
1419
1420         check_unused::check_crate(self, krate);
1421         self.report_errors();
1422         self.crate_loader.postprocess(krate);
1423     }
1424
1425     fn new_module(&self, parent: Module<'a>, kind: ModuleKind, normal_ancestor_id: DefId)
1426                   -> Module<'a> {
1427         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id))
1428     }
1429
1430     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1431                   -> bool /* true if an error was reported */ {
1432         match binding.kind {
1433             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1434                     if !used.get() => {
1435                 used.set(true);
1436                 directive.used.set(true);
1437                 if legacy_self_import {
1438                     self.warn_legacy_self_import(directive);
1439                     return false;
1440                 }
1441                 self.used_imports.insert((directive.id, ns));
1442                 self.add_to_glob_map(directive.id, ident);
1443                 self.record_use(ident, ns, binding, span)
1444             }
1445             NameBindingKind::Import { .. } => false,
1446             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1447                 self.ambiguity_errors.push(AmbiguityError {
1448                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1449                 });
1450                 if legacy {
1451                     self.record_use(ident, ns, b1, span);
1452                 }
1453                 !legacy
1454             }
1455             _ => false
1456         }
1457     }
1458
1459     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1460         if self.make_glob_map {
1461             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1462         }
1463     }
1464
1465     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1466     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1467     /// `ident` in the first scope that defines it (or None if no scopes define it).
1468     ///
1469     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1470     /// the items are defined in the block. For example,
1471     /// ```rust
1472     /// fn f() {
1473     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1474     ///    let g = || {};
1475     ///    fn g() {}
1476     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1477     /// }
1478     /// ```
1479     ///
1480     /// Invariant: This must only be called during main resolution, not during
1481     /// import resolution.
1482     fn resolve_ident_in_lexical_scope(&mut self,
1483                                       mut ident: Ident,
1484                                       ns: Namespace,
1485                                       record_used: Option<Span>)
1486                                       -> Option<LexicalScopeBinding<'a>> {
1487         if ns == TypeNS {
1488             ident = ident.unhygienize();
1489         }
1490
1491         // Walk backwards up the ribs in scope.
1492         for i in (0 .. self.ribs[ns].len()).rev() {
1493             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1494                 // The ident resolves to a type parameter or local variable.
1495                 return Some(LexicalScopeBinding::Def(
1496                     self.adjust_local_def(ns, i, def, record_used)
1497                 ));
1498             }
1499
1500             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1501                 let item = self.resolve_ident_in_module(module, ident, ns, false, record_used);
1502                 if let Ok(binding) = item {
1503                     // The ident resolves to an item.
1504                     return Some(LexicalScopeBinding::Item(binding));
1505                 }
1506
1507                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1508                 } else if !module.no_implicit_prelude {
1509                     return self.prelude.and_then(|prelude| {
1510                         self.resolve_ident_in_module(prelude, ident, ns, false, None).ok()
1511                     }).map(LexicalScopeBinding::Item)
1512                 } else {
1513                     return None;
1514                 }
1515             }
1516
1517             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1518                 // If an invocation of this macro created `ident`, give up on `ident`
1519                 // and switch to `ident`'s source from the macro definition.
1520                 let ctxt_data = ident.ctxt.data();
1521                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1522                     ident.ctxt = ctxt_data.prev_ctxt;
1523                 }
1524             }
1525         }
1526
1527         None
1528     }
1529
1530     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext) -> Module<'a> {
1531         let mut ctxt_data = crate_var_ctxt.data();
1532         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1533             ctxt_data = ctxt_data.prev_ctxt.data();
1534         }
1535         let module = self.macro_def_scope(ctxt_data.outer_mark);
1536         if module.is_local() { self.graph_root } else { module }
1537     }
1538
1539     // AST resolution
1540     //
1541     // We maintain a list of value ribs and type ribs.
1542     //
1543     // Simultaneously, we keep track of the current position in the module
1544     // graph in the `current_module` pointer. When we go to resolve a name in
1545     // the value or type namespaces, we first look through all the ribs and
1546     // then query the module graph. When we resolve a name in the module
1547     // namespace, we can skip all the ribs (since nested modules are not
1548     // allowed within blocks in Rust) and jump straight to the current module
1549     // graph node.
1550     //
1551     // Named implementations are handled separately. When we find a method
1552     // call, we consult the module node to find all of the implementations in
1553     // scope. This information is lazily cached in the module node. We then
1554     // generate a fake "implementation scope" containing all the
1555     // implementations thus found, for compatibility with old resolve pass.
1556
1557     fn with_scope<F>(&mut self, id: NodeId, f: F)
1558         where F: FnOnce(&mut Resolver)
1559     {
1560         let id = self.definitions.local_def_id(id);
1561         let module = self.module_map.get(&id).cloned(); // clones a reference
1562         if let Some(module) = module {
1563             // Move down in the graph.
1564             let orig_module = replace(&mut self.current_module, module);
1565             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1566             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1567
1568             self.finalize_current_module_macro_resolutions();
1569             f(self);
1570
1571             self.current_module = orig_module;
1572             self.ribs[ValueNS].pop();
1573             self.ribs[TypeNS].pop();
1574         } else {
1575             f(self);
1576         }
1577     }
1578
1579     /// Searches the current set of local scopes for labels.
1580     /// Stops after meeting a closure.
1581     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1582         for rib in self.label_ribs.iter().rev() {
1583             match rib.kind {
1584                 NormalRibKind => {
1585                     // Continue
1586                 }
1587                 MacroDefinition(def) => {
1588                     // If an invocation of this macro created `ident`, give up on `ident`
1589                     // and switch to `ident`'s source from the macro definition.
1590                     let ctxt_data = ident.ctxt.data();
1591                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1592                         ident.ctxt = ctxt_data.prev_ctxt;
1593                     }
1594                 }
1595                 _ => {
1596                     // Do not resolve labels across function boundary
1597                     return None;
1598                 }
1599             }
1600             let result = rib.bindings.get(&ident).cloned();
1601             if result.is_some() {
1602                 return result;
1603             }
1604         }
1605         None
1606     }
1607
1608     fn resolve_item(&mut self, item: &Item) {
1609         let name = item.ident.name;
1610
1611         debug!("(resolving item) resolving {}", name);
1612
1613         self.check_proc_macro_attrs(&item.attrs);
1614
1615         match item.node {
1616             ItemKind::Enum(_, ref generics) |
1617             ItemKind::Ty(_, ref generics) |
1618             ItemKind::Struct(_, ref generics) |
1619             ItemKind::Union(_, ref generics) |
1620             ItemKind::Fn(.., ref generics, _) => {
1621                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1622                                              |this| visit::walk_item(this, item));
1623             }
1624
1625             ItemKind::DefaultImpl(_, ref trait_ref) => {
1626                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1627                     // Resolve type arguments in trait path
1628                     visit::walk_trait_ref(this, trait_ref);
1629                 });
1630             }
1631             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1632                 self.resolve_implementation(generics,
1633                                             opt_trait_ref,
1634                                             &self_type,
1635                                             item.id,
1636                                             impl_items),
1637
1638             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1639                 // Create a new rib for the trait-wide type parameters.
1640                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1641                     let local_def_id = this.definitions.local_def_id(item.id);
1642                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1643                         this.visit_generics(generics);
1644                         walk_list!(this, visit_ty_param_bound, bounds);
1645
1646                         for trait_item in trait_items {
1647                             this.check_proc_macro_attrs(&trait_item.attrs);
1648
1649                             match trait_item.node {
1650                                 TraitItemKind::Const(_, ref default) => {
1651                                     // Only impose the restrictions of
1652                                     // ConstRibKind if there's an actual constant
1653                                     // expression in a provided default.
1654                                     if default.is_some() {
1655                                         this.with_constant_rib(|this| {
1656                                             visit::walk_trait_item(this, trait_item)
1657                                         });
1658                                     } else {
1659                                         visit::walk_trait_item(this, trait_item)
1660                                     }
1661                                 }
1662                                 TraitItemKind::Method(ref sig, _) => {
1663                                     let type_parameters =
1664                                         HasTypeParameters(&sig.generics,
1665                                                           MethodRibKind(!sig.decl.has_self()));
1666                                     this.with_type_parameter_rib(type_parameters, |this| {
1667                                         visit::walk_trait_item(this, trait_item)
1668                                     });
1669                                 }
1670                                 TraitItemKind::Type(..) => {
1671                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1672                                         visit::walk_trait_item(this, trait_item)
1673                                     });
1674                                 }
1675                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1676                             };
1677                         }
1678                     });
1679                 });
1680             }
1681
1682             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1683                 self.with_scope(item.id, |this| {
1684                     visit::walk_item(this, item);
1685                 });
1686             }
1687
1688             ItemKind::Const(..) | ItemKind::Static(..) => {
1689                 self.with_constant_rib(|this| {
1690                     visit::walk_item(this, item);
1691                 });
1692             }
1693
1694             ItemKind::Use(ref view_path) => {
1695                 match view_path.node {
1696                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1697                         // Resolve prefix of an import with empty braces (issue #28388).
1698                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1699                     }
1700                     _ => {}
1701                 }
1702             }
1703
1704             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) => {
1705                 // do nothing, these are just around to be encoded
1706             }
1707
1708             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1709         }
1710     }
1711
1712     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1713         where F: FnOnce(&mut Resolver)
1714     {
1715         match type_parameters {
1716             HasTypeParameters(generics, rib_kind) => {
1717                 let mut function_type_rib = Rib::new(rib_kind);
1718                 let mut seen_bindings = FxHashMap();
1719                 for type_parameter in &generics.ty_params {
1720                     let name = type_parameter.ident.name;
1721                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1722
1723                     if seen_bindings.contains_key(&name) {
1724                         let span = seen_bindings.get(&name).unwrap();
1725                         resolve_error(self,
1726                                       type_parameter.span,
1727                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1728                                                                                           span));
1729                     }
1730                     seen_bindings.entry(name).or_insert(type_parameter.span);
1731
1732                     // plain insert (no renaming)
1733                     let def_id = self.definitions.local_def_id(type_parameter.id);
1734                     let def = Def::TyParam(def_id);
1735                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1736                     self.record_def(type_parameter.id, PathResolution::new(def));
1737                 }
1738                 self.ribs[TypeNS].push(function_type_rib);
1739             }
1740
1741             NoTypeParameters => {
1742                 // Nothing to do.
1743             }
1744         }
1745
1746         f(self);
1747
1748         if let HasTypeParameters(..) = type_parameters {
1749             self.ribs[TypeNS].pop();
1750         }
1751     }
1752
1753     fn with_label_rib<F>(&mut self, f: F)
1754         where F: FnOnce(&mut Resolver)
1755     {
1756         self.label_ribs.push(Rib::new(NormalRibKind));
1757         f(self);
1758         self.label_ribs.pop();
1759     }
1760
1761     fn with_constant_rib<F>(&mut self, f: F)
1762         where F: FnOnce(&mut Resolver)
1763     {
1764         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1765         self.ribs[TypeNS].push(Rib::new(ConstantItemRibKind));
1766         f(self);
1767         self.ribs[TypeNS].pop();
1768         self.ribs[ValueNS].pop();
1769     }
1770
1771     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1772         where F: FnOnce(&mut Resolver) -> T
1773     {
1774         // Handle nested impls (inside fn bodies)
1775         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1776         let result = f(self);
1777         self.current_self_type = previous_value;
1778         result
1779     }
1780
1781     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1782         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1783     {
1784         let mut new_val = None;
1785         let mut new_id = None;
1786         if let Some(trait_ref) = opt_trait_ref {
1787             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1788                                               &trait_ref.path, PathSource::Trait).base_def();
1789             if def != Def::Err {
1790                 new_val = Some((def.def_id(), trait_ref.clone()));
1791                 new_id = Some(def.def_id());
1792             }
1793         }
1794         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1795         let result = f(self, new_id);
1796         self.current_trait_ref = original_trait_ref;
1797         result
1798     }
1799
1800     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1801         where F: FnOnce(&mut Resolver)
1802     {
1803         let mut self_type_rib = Rib::new(NormalRibKind);
1804
1805         // plain insert (no renaming, types are not currently hygienic....)
1806         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1807         self.ribs[TypeNS].push(self_type_rib);
1808         f(self);
1809         self.ribs[TypeNS].pop();
1810     }
1811
1812     fn resolve_implementation(&mut self,
1813                               generics: &Generics,
1814                               opt_trait_reference: &Option<TraitRef>,
1815                               self_type: &Ty,
1816                               item_id: NodeId,
1817                               impl_items: &[ImplItem]) {
1818         // If applicable, create a rib for the type parameters.
1819         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1820             // Dummy self type for better errors if `Self` is used in the trait path.
1821             this.with_self_rib(Def::SelfTy(None, None), |this| {
1822                 // Resolve the trait reference, if necessary.
1823                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1824                     let item_def_id = this.definitions.local_def_id(item_id);
1825                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1826                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1827                             // Resolve type arguments in trait path
1828                             visit::walk_trait_ref(this, trait_ref);
1829                         }
1830                         // Resolve the self type.
1831                         this.visit_ty(self_type);
1832                         // Resolve the type parameters.
1833                         this.visit_generics(generics);
1834                         this.with_current_self_type(self_type, |this| {
1835                             for impl_item in impl_items {
1836                                 this.check_proc_macro_attrs(&impl_item.attrs);
1837                                 this.resolve_visibility(&impl_item.vis);
1838                                 match impl_item.node {
1839                                     ImplItemKind::Const(..) => {
1840                                         // If this is a trait impl, ensure the const
1841                                         // exists in trait
1842                                         this.check_trait_item(impl_item.ident.name,
1843                                                             ValueNS,
1844                                                             impl_item.span,
1845                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1846                                         visit::walk_impl_item(this, impl_item);
1847                                     }
1848                                     ImplItemKind::Method(ref sig, _) => {
1849                                         // If this is a trait impl, ensure the method
1850                                         // exists in trait
1851                                         this.check_trait_item(impl_item.ident.name,
1852                                                             ValueNS,
1853                                                             impl_item.span,
1854                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1855
1856                                         // We also need a new scope for the method-
1857                                         // specific type parameters.
1858                                         let type_parameters =
1859                                             HasTypeParameters(&sig.generics,
1860                                                             MethodRibKind(!sig.decl.has_self()));
1861                                         this.with_type_parameter_rib(type_parameters, |this| {
1862                                             visit::walk_impl_item(this, impl_item);
1863                                         });
1864                                     }
1865                                     ImplItemKind::Type(ref ty) => {
1866                                         // If this is a trait impl, ensure the type
1867                                         // exists in trait
1868                                         this.check_trait_item(impl_item.ident.name,
1869                                                             TypeNS,
1870                                                             impl_item.span,
1871                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1872
1873                                         this.visit_ty(ty);
1874                                     }
1875                                     ImplItemKind::Macro(_) =>
1876                                         panic!("unexpanded macro in resolve!"),
1877                                 }
1878                             }
1879                         });
1880                     });
1881                 });
1882             });
1883         });
1884     }
1885
1886     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1887         where F: FnOnce(Name, &str) -> ResolutionError
1888     {
1889         // If there is a TraitRef in scope for an impl, then the method must be in the
1890         // trait.
1891         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1892             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1893                 let path_str = path_names_to_string(&trait_ref.path);
1894                 resolve_error(self, span, err(name, &path_str));
1895             }
1896         }
1897     }
1898
1899     fn resolve_local(&mut self, local: &Local) {
1900         // Resolve the type.
1901         walk_list!(self, visit_ty, &local.ty);
1902
1903         // Resolve the initializer.
1904         walk_list!(self, visit_expr, &local.init);
1905
1906         // Resolve the pattern.
1907         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1908     }
1909
1910     // build a map from pattern identifiers to binding-info's.
1911     // this is done hygienically. This could arise for a macro
1912     // that expands into an or-pattern where one 'x' was from the
1913     // user and one 'x' came from the macro.
1914     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1915         let mut binding_map = FxHashMap();
1916
1917         pat.walk(&mut |pat| {
1918             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1919                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1920                     Some(Def::Local(..)) => true,
1921                     _ => false,
1922                 } {
1923                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1924                     binding_map.insert(ident.node, binding_info);
1925                 }
1926             }
1927             true
1928         });
1929
1930         binding_map
1931     }
1932
1933     // check that all of the arms in an or-pattern have exactly the
1934     // same set of bindings, with the same binding modes for each.
1935     fn check_consistent_bindings(&mut self, arm: &Arm) {
1936         if arm.pats.is_empty() {
1937             return;
1938         }
1939
1940         let mut missing_vars = FxHashMap();
1941         let mut inconsistent_vars = FxHashMap();
1942         for (i, p) in arm.pats.iter().enumerate() {
1943             let map_i = self.binding_mode_map(&p);
1944
1945             for (j, q) in arm.pats.iter().enumerate() {
1946                 if i == j {
1947                     continue;
1948                 }
1949
1950                 let map_j = self.binding_mode_map(&q);
1951                 for (&key, &binding_i) in &map_i {
1952                     if map_j.len() == 0 {                   // Account for missing bindings when
1953                         let binding_error = missing_vars    // map_j has none.
1954                             .entry(key.name)
1955                             .or_insert(BindingError {
1956                                 name: key.name,
1957                                 origin: BTreeSet::new(),
1958                                 target: BTreeSet::new(),
1959                             });
1960                         binding_error.origin.insert(binding_i.span);
1961                         binding_error.target.insert(q.span);
1962                     }
1963                     for (&key_j, &binding_j) in &map_j {
1964                         match map_i.get(&key_j) {
1965                             None => {  // missing binding
1966                                 let binding_error = missing_vars
1967                                     .entry(key_j.name)
1968                                     .or_insert(BindingError {
1969                                         name: key_j.name,
1970                                         origin: BTreeSet::new(),
1971                                         target: BTreeSet::new(),
1972                                     });
1973                                 binding_error.origin.insert(binding_j.span);
1974                                 binding_error.target.insert(p.span);
1975                             }
1976                             Some(binding_i) => {  // check consistent binding
1977                                 if binding_i.binding_mode != binding_j.binding_mode {
1978                                     inconsistent_vars
1979                                         .entry(key.name)
1980                                         .or_insert((binding_j.span, binding_i.span));
1981                                 }
1982                             }
1983                         }
1984                     }
1985                 }
1986             }
1987         }
1988         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
1989         missing_vars.sort();
1990         for (_, v) in missing_vars {
1991             resolve_error(self,
1992                           *v.origin.iter().next().unwrap(),
1993                           ResolutionError::VariableNotBoundInPattern(v));
1994         }
1995         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
1996         inconsistent_vars.sort();
1997         for (name, v) in inconsistent_vars {
1998             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
1999         }
2000     }
2001
2002     fn resolve_arm(&mut self, arm: &Arm) {
2003         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2004
2005         let mut bindings_list = FxHashMap();
2006         for pattern in &arm.pats {
2007             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2008         }
2009
2010         // This has to happen *after* we determine which
2011         // pat_idents are variants
2012         self.check_consistent_bindings(arm);
2013
2014         walk_list!(self, visit_expr, &arm.guard);
2015         self.visit_expr(&arm.body);
2016
2017         self.ribs[ValueNS].pop();
2018     }
2019
2020     fn resolve_block(&mut self, block: &Block) {
2021         debug!("(resolving block) entering block");
2022         // Move down in the graph, if there's an anonymous module rooted here.
2023         let orig_module = self.current_module;
2024         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2025
2026         let mut num_macro_definition_ribs = 0;
2027         if let Some(anonymous_module) = anonymous_module {
2028             debug!("(resolving block) found anonymous module, moving down");
2029             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2030             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2031             self.current_module = anonymous_module;
2032             self.finalize_current_module_macro_resolutions();
2033         } else {
2034             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2035         }
2036
2037         // Descend into the block.
2038         for stmt in &block.stmts {
2039             if let ast::StmtKind::Item(ref item) = stmt.node {
2040                 if let ast::ItemKind::MacroDef(..) = item.node {
2041                     num_macro_definition_ribs += 1;
2042                     let def = self.definitions.local_def_id(item.id);
2043                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2044                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2045                 }
2046             }
2047
2048             self.visit_stmt(stmt);
2049         }
2050
2051         // Move back up.
2052         self.current_module = orig_module;
2053         for _ in 0 .. num_macro_definition_ribs {
2054             self.ribs[ValueNS].pop();
2055             self.label_ribs.pop();
2056         }
2057         self.ribs[ValueNS].pop();
2058         if let Some(_) = anonymous_module {
2059             self.ribs[TypeNS].pop();
2060         }
2061         debug!("(resolving block) leaving block");
2062     }
2063
2064     fn fresh_binding(&mut self,
2065                      ident: &SpannedIdent,
2066                      pat_id: NodeId,
2067                      outer_pat_id: NodeId,
2068                      pat_src: PatternSource,
2069                      bindings: &mut FxHashMap<Ident, NodeId>)
2070                      -> PathResolution {
2071         // Add the binding to the local ribs, if it
2072         // doesn't already exist in the bindings map. (We
2073         // must not add it if it's in the bindings map
2074         // because that breaks the assumptions later
2075         // passes make about or-patterns.)
2076         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2077         match bindings.get(&ident.node).cloned() {
2078             Some(id) if id == outer_pat_id => {
2079                 // `Variant(a, a)`, error
2080                 resolve_error(
2081                     self,
2082                     ident.span,
2083                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2084                         &ident.node.name.as_str())
2085                 );
2086             }
2087             Some(..) if pat_src == PatternSource::FnParam => {
2088                 // `fn f(a: u8, a: u8)`, error
2089                 resolve_error(
2090                     self,
2091                     ident.span,
2092                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2093                         &ident.node.name.as_str())
2094                 );
2095             }
2096             Some(..) if pat_src == PatternSource::Match => {
2097                 // `Variant1(a) | Variant2(a)`, ok
2098                 // Reuse definition from the first `a`.
2099                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2100             }
2101             Some(..) => {
2102                 span_bug!(ident.span, "two bindings with the same name from \
2103                                        unexpected pattern source {:?}", pat_src);
2104             }
2105             None => {
2106                 // A completely fresh binding, add to the lists if it's valid.
2107                 if ident.node.name != keywords::Invalid.name() {
2108                     bindings.insert(ident.node, outer_pat_id);
2109                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2110                 }
2111             }
2112         }
2113
2114         PathResolution::new(def)
2115     }
2116
2117     fn resolve_pattern(&mut self,
2118                        pat: &Pat,
2119                        pat_src: PatternSource,
2120                        // Maps idents to the node ID for the
2121                        // outermost pattern that binds them.
2122                        bindings: &mut FxHashMap<Ident, NodeId>) {
2123         // Visit all direct subpatterns of this pattern.
2124         let outer_pat_id = pat.id;
2125         pat.walk(&mut |pat| {
2126             match pat.node {
2127                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2128                     // First try to resolve the identifier as some existing
2129                     // entity, then fall back to a fresh binding.
2130                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS, None)
2131                                       .and_then(LexicalScopeBinding::item);
2132                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2133                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2134                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2135                         match def {
2136                             Def::StructCtor(_, CtorKind::Const) |
2137                             Def::VariantCtor(_, CtorKind::Const) |
2138                             Def::Const(..) if !always_binding => {
2139                                 // A unit struct/variant or constant pattern.
2140                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2141                                 Some(PathResolution::new(def))
2142                             }
2143                             Def::StructCtor(..) | Def::VariantCtor(..) |
2144                             Def::Const(..) | Def::Static(..) => {
2145                                 // A fresh binding that shadows something unacceptable.
2146                                 resolve_error(
2147                                     self,
2148                                     ident.span,
2149                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2150                                         pat_src.descr(), ident.node.name, binding.unwrap())
2151                                 );
2152                                 None
2153                             }
2154                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2155                                 // These entities are explicitly allowed
2156                                 // to be shadowed by fresh bindings.
2157                                 None
2158                             }
2159                             def => {
2160                                 span_bug!(ident.span, "unexpected definition for an \
2161                                                        identifier in pattern: {:?}", def);
2162                             }
2163                         }
2164                     }).unwrap_or_else(|| {
2165                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2166                     });
2167
2168                     self.record_def(pat.id, resolution);
2169                 }
2170
2171                 PatKind::TupleStruct(ref path, ..) => {
2172                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2173                 }
2174
2175                 PatKind::Path(ref qself, ref path) => {
2176                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2177                 }
2178
2179                 PatKind::Struct(ref path, ..) => {
2180                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2181                 }
2182
2183                 _ => {}
2184             }
2185             true
2186         });
2187
2188         visit::walk_pat(self, pat);
2189     }
2190
2191     // High-level and context dependent path resolution routine.
2192     // Resolves the path and records the resolution into definition map.
2193     // If resolution fails tries several techniques to find likely
2194     // resolution candidates, suggest imports or other help, and report
2195     // errors in user friendly way.
2196     fn smart_resolve_path(&mut self,
2197                           id: NodeId,
2198                           qself: Option<&QSelf>,
2199                           path: &Path,
2200                           source: PathSource)
2201                           -> PathResolution {
2202         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2203         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2204         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2205     }
2206
2207     fn smart_resolve_path_fragment(&mut self,
2208                                    id: NodeId,
2209                                    qself: Option<&QSelf>,
2210                                    path: &[Ident],
2211                                    span: Span,
2212                                    ident_span: Span,
2213                                    source: PathSource)
2214                                    -> PathResolution {
2215         let ns = source.namespace();
2216         let is_expected = &|def| source.is_expected(def);
2217
2218         // Base error is amended with one short label and possibly some longer helps/notes.
2219         let report_errors = |this: &mut Self, def: Option<Def>| {
2220             // Make the base error.
2221             let expected = source.descr_expected();
2222             let path_str = names_to_string(path);
2223             let code = source.error_code(def.is_some());
2224             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2225                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2226                  format!("not a {}", expected), span)
2227             } else {
2228                 let item_str = path[path.len() - 1];
2229                 let (mod_prefix, mod_str) = if path.len() == 1 {
2230                     (format!(""), format!("this scope"))
2231                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2232                     (format!(""), format!("the crate root"))
2233                 } else {
2234                     let mod_path = &path[..path.len() - 1];
2235                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), None) {
2236                         PathResult::Module(module) => module.def(),
2237                         _ => None,
2238                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2239                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2240                 };
2241                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2242                  format!("not found in {}", mod_str), ident_span)
2243             };
2244             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2245
2246             // Emit special messages for unresolved `Self` and `self`.
2247             if is_self_type(path, ns) {
2248                 __diagnostic_used!(E0411);
2249                 err.code("E0411".into());
2250                 err.span_label(span, &format!("`Self` is only available in traits and impls"));
2251                 return err;
2252             }
2253             if is_self_value(path, ns) {
2254                 __diagnostic_used!(E0424);
2255                 err.code("E0424".into());
2256                 err.span_label(span, &format!("`self` value is only available in \
2257                                                methods with `self` parameter"));
2258                 return err;
2259             }
2260
2261             // Try to lookup the name in more relaxed fashion for better error reporting.
2262             let name = path.last().unwrap().name;
2263             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2264             if !candidates.is_empty() {
2265                 // Report import candidates as help and proceed searching for labels.
2266                 show_candidates(&mut err, &candidates, def.is_some());
2267             }
2268             if path.len() == 1 && this.self_type_is_available() {
2269                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2270                     let self_is_available = this.self_value_is_available(path[0].ctxt);
2271                     match candidate {
2272                         AssocSuggestion::Field => {
2273                             err.span_label(span, &format!("did you mean `self.{}`?", path_str));
2274                             if !self_is_available {
2275                                 err.span_label(span, &format!("`self` value is only available in \
2276                                                                methods with `self` parameter"));
2277                             }
2278                         }
2279                         AssocSuggestion::MethodWithSelf if self_is_available => {
2280                             err.span_label(span, &format!("did you mean `self.{}(...)`?",
2281                                                            path_str));
2282                         }
2283                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2284                             err.span_label(span, &format!("did you mean `Self::{}`?", path_str));
2285                         }
2286                     }
2287                     return err;
2288                 }
2289             }
2290
2291             // Try context dependent help if relaxed lookup didn't work.
2292             if let Some(def) = def {
2293                 match (def, source) {
2294                     (Def::Macro(..), _) => {
2295                         err.span_label(span, &format!("did you mean `{}!(...)`?", path_str));
2296                         return err;
2297                     }
2298                     (Def::TyAlias(..), PathSource::Trait) => {
2299                         err.span_label(span, &format!("type aliases cannot be used for traits"));
2300                         return err;
2301                     }
2302                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2303                         ExprKind::Field(_, ident) => {
2304                             err.span_label(parent.span, &format!("did you mean `{}::{}`?",
2305                                                                  path_str, ident.node));
2306                             return err;
2307                         }
2308                         ExprKind::MethodCall(ident, ..) => {
2309                             err.span_label(parent.span, &format!("did you mean `{}::{}(...)`?",
2310                                                                  path_str, ident.node));
2311                             return err;
2312                         }
2313                         _ => {}
2314                     },
2315                     _ if ns == ValueNS && is_struct_like(def) => {
2316                         if let Def::Struct(def_id) = def {
2317                             if let Some((ctor_def, ctor_vis))
2318                                     = this.struct_constructors.get(&def_id).cloned() {
2319                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2320                                     err.span_label(span, &format!("constructor is not visible \
2321                                                                    here due to private fields"));
2322                                 }
2323                             }
2324                         }
2325                         err.span_label(span, &format!("did you mean `{} {{ /* fields */ }}`?",
2326                                                        path_str));
2327                         return err;
2328                     }
2329                     _ => {}
2330                 }
2331             }
2332
2333             // Try Levenshtein if nothing else worked.
2334             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected) {
2335                 err.span_label(ident_span, &format!("did you mean `{}`?", candidate));
2336                 return err;
2337             }
2338
2339             // Fallback label.
2340             err.span_label(base_span, &fallback_label);
2341             err
2342         };
2343         let report_errors = |this: &mut Self, def: Option<Def>| {
2344             report_errors(this, def).emit();
2345             err_path_resolution()
2346         };
2347
2348         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2349                                                            source.defer_to_typeck(),
2350                                                            source.global_by_default()) {
2351             Some(resolution) if resolution.unresolved_segments() == 0 => {
2352                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2353                     resolution
2354                 } else {
2355                     // Add a temporary hack to smooth the transition to new struct ctor
2356                     // visibility rules. See #38932 for more details.
2357                     let mut res = None;
2358                     if let Def::Struct(def_id) = resolution.base_def() {
2359                         if let Some((ctor_def, ctor_vis))
2360                                 = self.struct_constructors.get(&def_id).cloned() {
2361                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2362                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2363                                 self.session.add_lint(lint, id, span,
2364                                     "private struct constructors are not usable through \
2365                                      reexports in outer modules".to_string());
2366                                 res = Some(PathResolution::new(ctor_def));
2367                             }
2368                         }
2369                     }
2370
2371                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2372                 }
2373             }
2374             Some(resolution) if source.defer_to_typeck() => {
2375                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2376                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2377                 // it needs to be added to the trait map.
2378                 if ns == ValueNS {
2379                     let item_name = path.last().unwrap().name;
2380                     let traits = self.get_traits_containing_item(item_name, ns);
2381                     self.trait_map.insert(id, traits);
2382                 }
2383                 resolution
2384             }
2385             _ => report_errors(self, None)
2386         };
2387
2388         if let PathSource::TraitItem(..) = source {} else {
2389             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2390             self.record_def(id, resolution);
2391         }
2392         resolution
2393     }
2394
2395     fn self_type_is_available(&mut self) -> bool {
2396         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(), TypeNS, None);
2397         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2398     }
2399
2400     fn self_value_is_available(&mut self, ctxt: SyntaxContext) -> bool {
2401         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2402         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, None);
2403         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2404     }
2405
2406     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2407     fn resolve_qpath_anywhere(&mut self,
2408                               id: NodeId,
2409                               qself: Option<&QSelf>,
2410                               path: &[Ident],
2411                               primary_ns: Namespace,
2412                               span: Span,
2413                               defer_to_typeck: bool,
2414                               global_by_default: bool)
2415                               -> Option<PathResolution> {
2416         let mut fin_res = None;
2417         // FIXME: can't resolve paths in macro namespace yet, macros are
2418         // processed by the little special hack below.
2419         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2420             if i == 0 || ns != primary_ns {
2421                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2422                     // If defer_to_typeck, then resolution > no resolution,
2423                     // otherwise full resolution > partial resolution > no resolution.
2424                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2425                         return Some(res),
2426                     res => if fin_res.is_none() { fin_res = res },
2427                 };
2428             }
2429         }
2430         let is_builtin = self.builtin_macros.get(&path[0].name).cloned()
2431             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2432         if primary_ns != MacroNS && (is_builtin || self.macro_names.contains(&path[0].name)) {
2433             // Return some dummy definition, it's enough for error reporting.
2434             return Some(
2435                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2436             );
2437         }
2438         fin_res
2439     }
2440
2441     /// Handles paths that may refer to associated items.
2442     fn resolve_qpath(&mut self,
2443                      id: NodeId,
2444                      qself: Option<&QSelf>,
2445                      path: &[Ident],
2446                      ns: Namespace,
2447                      span: Span,
2448                      global_by_default: bool)
2449                      -> Option<PathResolution> {
2450         if let Some(qself) = qself {
2451             if qself.position == 0 {
2452                 // FIXME: Create some fake resolution that can't possibly be a type.
2453                 return Some(PathResolution::with_unresolved_segments(
2454                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2455                 ));
2456             }
2457             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2458             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2459             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2460                                                        span, span, PathSource::TraitItem(ns));
2461             return Some(PathResolution::with_unresolved_segments(
2462                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2463             ));
2464         }
2465
2466         let result = match self.resolve_path(&path, Some(ns), Some(span)) {
2467             PathResult::NonModule(path_res) => path_res,
2468             PathResult::Module(module) if !module.is_normal() => {
2469                 PathResolution::new(module.def().unwrap())
2470             }
2471             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2472             // don't report an error right away, but try to fallback to a primitive type.
2473             // So, we are still able to successfully resolve something like
2474             //
2475             // use std::u8; // bring module u8 in scope
2476             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2477             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2478             //                     // not to non-existent std::u8::max_value
2479             // }
2480             //
2481             // Such behavior is required for backward compatibility.
2482             // The same fallback is used when `a` resolves to nothing.
2483             PathResult::Module(..) | PathResult::Failed(..)
2484                     if (ns == TypeNS || path.len() > 1) &&
2485                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2486                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2487                 match prim {
2488                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2489                         if !self.session.features.borrow().i128_type {
2490                             emit_feature_err(&self.session.parse_sess,
2491                                                 "i128_type", span, GateIssue::Language,
2492                                                 "128-bit type is unstable");
2493
2494                         }
2495                     }
2496                     _ => {}
2497                 }
2498                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2499             }
2500             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2501             PathResult::Failed(msg, false) => {
2502                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2503                 err_path_resolution()
2504             }
2505             PathResult::Failed(..) => return None,
2506             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2507         };
2508
2509         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2510            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2511             let unqualified_result = {
2512                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), None) {
2513                     PathResult::NonModule(path_res) => path_res.base_def(),
2514                     PathResult::Module(module) => module.def().unwrap(),
2515                     _ => return Some(result),
2516                 }
2517             };
2518             if result.base_def() == unqualified_result {
2519                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2520                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2521             }
2522         }
2523
2524         Some(result)
2525     }
2526
2527     fn resolve_path(&mut self,
2528                     path: &[Ident],
2529                     opt_ns: Option<Namespace>, // `None` indicates a module path
2530                     record_used: Option<Span>)
2531                     -> PathResult<'a> {
2532         let mut module = None;
2533         let mut allow_super = true;
2534
2535         for (i, &ident) in path.iter().enumerate() {
2536             let is_last = i == path.len() - 1;
2537             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2538
2539             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2540                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2541                 continue
2542             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2543                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2544                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2545                 if let Some(parent) = self_module.parent {
2546                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2547                     continue
2548                 } else {
2549                     let msg = "There are too many initial `super`s.".to_string();
2550                     return PathResult::Failed(msg, false);
2551                 }
2552             }
2553             allow_super = false;
2554
2555             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2556                 module = Some(self.graph_root);
2557                 continue
2558             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2559                 module = Some(self.resolve_crate_var(ident.ctxt));
2560                 continue
2561             }
2562
2563             let binding = if let Some(module) = module {
2564                 self.resolve_ident_in_module(module, ident, ns, false, record_used)
2565             } else if opt_ns == Some(MacroNS) {
2566                 self.resolve_lexical_macro_path_segment(ident, ns, record_used)
2567             } else {
2568                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used) {
2569                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2570                     Some(LexicalScopeBinding::Def(def))
2571                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2572                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2573                             def, path.len() - 1
2574                         ));
2575                     }
2576                     _ => Err(if record_used.is_some() { Determined } else { Undetermined }),
2577                 }
2578             };
2579
2580             match binding {
2581                 Ok(binding) => {
2582                     let def = binding.def();
2583                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2584                     if let Some(next_module) = binding.module() {
2585                         module = Some(next_module);
2586                     } else if def == Def::Err {
2587                         return PathResult::NonModule(err_path_resolution());
2588                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2589                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2590                             def, path.len() - i - 1
2591                         ));
2592                     } else {
2593                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2594                     }
2595                 }
2596                 Err(Undetermined) => return PathResult::Indeterminate,
2597                 Err(Determined) => {
2598                     if let Some(module) = module {
2599                         if opt_ns.is_some() && !module.is_normal() {
2600                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2601                                 module.def().unwrap(), path.len() - i
2602                             ));
2603                         }
2604                     }
2605                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2606                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2607                         let mut candidates =
2608                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2609                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2610                         if let Some(candidate) = candidates.get(0) {
2611                             format!("Did you mean `{}`?", candidate.path)
2612                         } else {
2613                             format!("Maybe a missing `extern crate {};`?", ident)
2614                         }
2615                     } else if i == 0 {
2616                         format!("Use of undeclared type or module `{}`", ident)
2617                     } else {
2618                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2619                     };
2620                     return PathResult::Failed(msg, is_last);
2621                 }
2622             }
2623         }
2624
2625         PathResult::Module(module.unwrap_or(self.graph_root))
2626     }
2627
2628     // Resolve a local definition, potentially adjusting for closures.
2629     fn adjust_local_def(&mut self,
2630                         ns: Namespace,
2631                         rib_index: usize,
2632                         mut def: Def,
2633                         record_used: Option<Span>) -> Def {
2634         let ribs = &self.ribs[ns][rib_index + 1..];
2635
2636         // An invalid forward use of a type parameter from a previous default.
2637         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2638             if let Some(span) = record_used {
2639                 resolve_error(self, span,
2640                         ResolutionError::ForwardDeclaredTyParam);
2641             }
2642             assert_eq!(def, Def::Err);
2643             return Def::Err;
2644         }
2645
2646         match def {
2647             Def::Upvar(..) => {
2648                 span_bug!(record_used.unwrap_or(DUMMY_SP), "unexpected {:?} in bindings", def)
2649             }
2650             Def::Local(def_id) => {
2651                 for rib in ribs {
2652                     match rib.kind {
2653                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2654                         ForwardTyParamBanRibKind => {
2655                             // Nothing to do. Continue.
2656                         }
2657                         ClosureRibKind(function_id) => {
2658                             let prev_def = def;
2659                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2660
2661                             let seen = self.freevars_seen
2662                                            .entry(function_id)
2663                                            .or_insert_with(|| NodeMap());
2664                             if let Some(&index) = seen.get(&node_id) {
2665                                 def = Def::Upvar(def_id, index, function_id);
2666                                 continue;
2667                             }
2668                             let vec = self.freevars
2669                                           .entry(function_id)
2670                                           .or_insert_with(|| vec![]);
2671                             let depth = vec.len();
2672                             def = Def::Upvar(def_id, depth, function_id);
2673
2674                             if let Some(span) = record_used {
2675                                 vec.push(Freevar {
2676                                     def: prev_def,
2677                                     span: span,
2678                                 });
2679                                 seen.insert(node_id, depth);
2680                             }
2681                         }
2682                         ItemRibKind | MethodRibKind(_) => {
2683                             // This was an attempt to access an upvar inside a
2684                             // named function item. This is not allowed, so we
2685                             // report an error.
2686                             if let Some(span) = record_used {
2687                                 resolve_error(self, span,
2688                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2689                             }
2690                             return Def::Err;
2691                         }
2692                         ConstantItemRibKind => {
2693                             // Still doesn't deal with upvars
2694                             if let Some(span) = record_used {
2695                                 resolve_error(self, span,
2696                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2697                             }
2698                             return Def::Err;
2699                         }
2700                     }
2701                 }
2702             }
2703             Def::TyParam(..) | Def::SelfTy(..) => {
2704                 for rib in ribs {
2705                     match rib.kind {
2706                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2707                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind => {
2708                             // Nothing to do. Continue.
2709                         }
2710                         ItemRibKind => {
2711                             // This was an attempt to use a type parameter outside
2712                             // its scope.
2713                             if let Some(span) = record_used {
2714                                 resolve_error(self, span,
2715                                               ResolutionError::TypeParametersFromOuterFunction);
2716                             }
2717                             return Def::Err;
2718                         }
2719                         ConstantItemRibKind => {
2720                             // see #9186
2721                             if let Some(span) = record_used {
2722                                 resolve_error(self, span,
2723                                               ResolutionError::OuterTypeParameterContext);
2724                             }
2725                             return Def::Err;
2726                         }
2727                     }
2728                 }
2729             }
2730             _ => {}
2731         }
2732         return def;
2733     }
2734
2735     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2736     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2737     // FIXME #34673: This needs testing.
2738     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2739         where F: FnOnce(&mut Resolver<'a>) -> T,
2740     {
2741         self.with_empty_ribs(|this| {
2742             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2743             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2744             f(this)
2745         })
2746     }
2747
2748     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2749         where F: FnOnce(&mut Resolver<'a>) -> T,
2750     {
2751         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2752         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2753
2754         let result = f(self);
2755         self.ribs = ribs;
2756         self.label_ribs = label_ribs;
2757         result
2758     }
2759
2760     fn lookup_assoc_candidate<FilterFn>(&mut self,
2761                                         name: Name,
2762                                         ns: Namespace,
2763                                         filter_fn: FilterFn)
2764                                         -> Option<AssocSuggestion>
2765         where FilterFn: Fn(Def) -> bool
2766     {
2767         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2768             match t.node {
2769                 TyKind::Path(None, _) => Some(t.id),
2770                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2771                 // This doesn't handle the remaining `Ty` variants as they are not
2772                 // that commonly the self_type, it might be interesting to provide
2773                 // support for those in future.
2774                 _ => None,
2775             }
2776         }
2777
2778         // Fields are generally expected in the same contexts as locals.
2779         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2780             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2781                 // Look for a field with the same name in the current self_type.
2782                 if let Some(resolution) = self.def_map.get(&node_id) {
2783                     match resolution.base_def() {
2784                         Def::Struct(did) | Def::Union(did)
2785                                 if resolution.unresolved_segments() == 0 => {
2786                             if let Some(field_names) = self.field_names.get(&did) {
2787                                 if field_names.iter().any(|&field_name| name == field_name) {
2788                                     return Some(AssocSuggestion::Field);
2789                                 }
2790                             }
2791                         }
2792                         _ => {}
2793                     }
2794                 }
2795             }
2796         }
2797
2798         // Look for associated items in the current trait.
2799         if let Some((trait_did, _)) = self.current_trait_ref {
2800             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2801                 if filter_fn(def) {
2802                     return Some(if has_self {
2803                         AssocSuggestion::MethodWithSelf
2804                     } else {
2805                         AssocSuggestion::AssocItem
2806                     });
2807                 }
2808             }
2809         }
2810
2811         None
2812     }
2813
2814     fn lookup_typo_candidate<FilterFn>(&mut self,
2815                                        path: &[Ident],
2816                                        ns: Namespace,
2817                                        filter_fn: FilterFn)
2818                                        -> Option<Symbol>
2819         where FilterFn: Fn(Def) -> bool
2820     {
2821         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2822             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2823                 if let Some(binding) = resolution.borrow().binding {
2824                     if filter_fn(binding.def()) {
2825                         names.push(ident.name);
2826                     }
2827                 }
2828             }
2829         };
2830
2831         let mut names = Vec::new();
2832         if path.len() == 1 {
2833             // Search in lexical scope.
2834             // Walk backwards up the ribs in scope and collect candidates.
2835             for rib in self.ribs[ns].iter().rev() {
2836                 // Locals and type parameters
2837                 for (ident, def) in &rib.bindings {
2838                     if filter_fn(*def) {
2839                         names.push(ident.name);
2840                     }
2841                 }
2842                 // Items in scope
2843                 if let ModuleRibKind(module) = rib.kind {
2844                     // Items from this module
2845                     add_module_candidates(module, &mut names);
2846
2847                     if let ModuleKind::Block(..) = module.kind {
2848                         // We can see through blocks
2849                     } else {
2850                         // Items from the prelude
2851                         if let Some(prelude) = self.prelude {
2852                             if !module.no_implicit_prelude {
2853                                 add_module_candidates(prelude, &mut names);
2854                             }
2855                         }
2856                         break;
2857                     }
2858                 }
2859             }
2860             // Add primitive types to the mix
2861             if filter_fn(Def::PrimTy(TyBool)) {
2862                 for (name, _) in &self.primitive_type_table.primitive_types {
2863                     names.push(*name);
2864                 }
2865             }
2866         } else {
2867             // Search in module.
2868             let mod_path = &path[..path.len() - 1];
2869             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS), None) {
2870                 add_module_candidates(module, &mut names);
2871             }
2872         }
2873
2874         let name = path[path.len() - 1].name;
2875         // Make sure error reporting is deterministic.
2876         names.sort_by_key(|name| name.as_str());
2877         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2878             Some(found) if found != name => Some(found),
2879             _ => None,
2880         }
2881     }
2882
2883     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2884         where F: FnOnce(&mut Resolver)
2885     {
2886         if let Some(label) = label {
2887             let def = Def::Label(id);
2888             self.with_label_rib(|this| {
2889                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2890                 f(this);
2891             });
2892         } else {
2893             f(self);
2894         }
2895     }
2896
2897     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2898         self.with_resolved_label(label, id, |this| this.visit_block(block));
2899     }
2900
2901     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2902         // First, record candidate traits for this expression if it could
2903         // result in the invocation of a method call.
2904
2905         self.record_candidate_traits_for_expr_if_necessary(expr);
2906
2907         // Next, resolve the node.
2908         match expr.node {
2909             ExprKind::Path(ref qself, ref path) => {
2910                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2911                 visit::walk_expr(self, expr);
2912             }
2913
2914             ExprKind::Struct(ref path, ..) => {
2915                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2916                 visit::walk_expr(self, expr);
2917             }
2918
2919             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2920                 match self.search_label(label.node) {
2921                     None => {
2922                         self.record_def(expr.id, err_path_resolution());
2923                         resolve_error(self,
2924                                       label.span,
2925                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2926                     }
2927                     Some(def @ Def::Label(_)) => {
2928                         // Since this def is a label, it is never read.
2929                         self.record_def(expr.id, PathResolution::new(def));
2930                     }
2931                     Some(_) => {
2932                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2933                     }
2934                 }
2935
2936                 // visit `break` argument if any
2937                 visit::walk_expr(self, expr);
2938             }
2939
2940             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2941                 self.visit_expr(subexpression);
2942
2943                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2944                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
2945                 self.visit_block(if_block);
2946                 self.ribs[ValueNS].pop();
2947
2948                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
2949             }
2950
2951             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
2952
2953             ExprKind::While(ref subexpression, ref block, label) => {
2954                 self.with_resolved_label(label, expr.id, |this| {
2955                     this.visit_expr(subexpression);
2956                     this.visit_block(block);
2957                 });
2958             }
2959
2960             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
2961                 self.with_resolved_label(label, expr.id, |this| {
2962                     this.visit_expr(subexpression);
2963                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
2964                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
2965                     this.visit_block(block);
2966                     this.ribs[ValueNS].pop();
2967                 });
2968             }
2969
2970             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
2971                 self.visit_expr(subexpression);
2972                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2973                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
2974
2975                 self.resolve_labeled_block(label, expr.id, block);
2976
2977                 self.ribs[ValueNS].pop();
2978             }
2979
2980             // Equivalent to `visit::walk_expr` + passing some context to children.
2981             ExprKind::Field(ref subexpression, _) => {
2982                 self.resolve_expr(subexpression, Some(expr));
2983             }
2984             ExprKind::MethodCall(_, ref types, ref arguments) => {
2985                 let mut arguments = arguments.iter();
2986                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
2987                 for argument in arguments {
2988                     self.resolve_expr(argument, None);
2989                 }
2990                 for ty in types.iter() {
2991                     self.visit_ty(ty);
2992                 }
2993             }
2994
2995             ExprKind::Repeat(ref element, ref count) => {
2996                 self.visit_expr(element);
2997                 self.with_constant_rib(|this| {
2998                     this.visit_expr(count);
2999                 });
3000             }
3001             ExprKind::Call(ref callee, ref arguments) => {
3002                 self.resolve_expr(callee, Some(expr));
3003                 for argument in arguments {
3004                     self.resolve_expr(argument, None);
3005                 }
3006             }
3007
3008             _ => {
3009                 visit::walk_expr(self, expr);
3010             }
3011         }
3012     }
3013
3014     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3015         match expr.node {
3016             ExprKind::Field(_, name) => {
3017                 // FIXME(#6890): Even though you can't treat a method like a
3018                 // field, we need to add any trait methods we find that match
3019                 // the field name so that we can do some nice error reporting
3020                 // later on in typeck.
3021                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3022                 self.trait_map.insert(expr.id, traits);
3023             }
3024             ExprKind::MethodCall(name, ..) => {
3025                 debug!("(recording candidate traits for expr) recording traits for {}",
3026                        expr.id);
3027                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3028                 self.trait_map.insert(expr.id, traits);
3029             }
3030             _ => {
3031                 // Nothing to do.
3032             }
3033         }
3034     }
3035
3036     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3037         debug!("(getting traits containing item) looking for '{}'", name);
3038
3039         let mut found_traits = Vec::new();
3040         // Look for the current trait.
3041         if let Some((trait_def_id, _)) = self.current_trait_ref {
3042             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3043                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3044             }
3045         }
3046
3047         let mut search_module = self.current_module;
3048         loop {
3049             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3050             match search_module.kind {
3051                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3052                 _ => break,
3053             }
3054         }
3055
3056         if let Some(prelude) = self.prelude {
3057             if !search_module.no_implicit_prelude {
3058                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3059             }
3060         }
3061
3062         found_traits
3063     }
3064
3065     fn get_traits_in_module_containing_item(&mut self,
3066                                             name: Name,
3067                                             ns: Namespace,
3068                                             module: Module,
3069                                             found_traits: &mut Vec<TraitCandidate>) {
3070         let mut traits = module.traits.borrow_mut();
3071         if traits.is_none() {
3072             let mut collected_traits = Vec::new();
3073             module.for_each_child(|name, ns, binding| {
3074                 if ns != TypeNS { return }
3075                 if let Def::Trait(_) = binding.def() {
3076                     collected_traits.push((name, binding));
3077                 }
3078             });
3079             *traits = Some(collected_traits.into_boxed_slice());
3080         }
3081
3082         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3083             let trait_def_id = binding.def().def_id();
3084             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3085                 let import_id = match binding.kind {
3086                     NameBindingKind::Import { directive, .. } => {
3087                         self.maybe_unused_trait_imports.insert(directive.id);
3088                         self.add_to_glob_map(directive.id, trait_name);
3089                         Some(directive.id)
3090                     }
3091                     _ => None,
3092                 };
3093                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3094             }
3095         }
3096     }
3097
3098     /// When name resolution fails, this method can be used to look up candidate
3099     /// entities with the expected name. It allows filtering them using the
3100     /// supplied predicate (which should be used to only accept the types of
3101     /// definitions expected e.g. traits). The lookup spans across all crates.
3102     ///
3103     /// NOTE: The method does not look into imports, but this is not a problem,
3104     /// since we report the definitions (thus, the de-aliased imports).
3105     fn lookup_import_candidates<FilterFn>(&mut self,
3106                                           lookup_name: Name,
3107                                           namespace: Namespace,
3108                                           filter_fn: FilterFn)
3109                                           -> Vec<ImportSuggestion>
3110         where FilterFn: Fn(Def) -> bool
3111     {
3112         let mut candidates = Vec::new();
3113         let mut worklist = Vec::new();
3114         let mut seen_modules = FxHashSet();
3115         worklist.push((self.graph_root, Vec::new(), false));
3116
3117         while let Some((in_module,
3118                         path_segments,
3119                         in_module_is_extern)) = worklist.pop() {
3120             self.populate_module_if_necessary(in_module);
3121
3122             in_module.for_each_child(|ident, ns, name_binding| {
3123
3124                 // avoid imports entirely
3125                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3126                 // avoid non-importable candidates as well
3127                 if !name_binding.is_importable() { return; }
3128
3129                 // collect results based on the filter function
3130                 if ident.name == lookup_name && ns == namespace {
3131                     if filter_fn(name_binding.def()) {
3132                         // create the path
3133                         let mut segms = path_segments.clone();
3134                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3135                         let path = Path {
3136                             span: name_binding.span,
3137                             segments: segms,
3138                         };
3139                         // the entity is accessible in the following cases:
3140                         // 1. if it's defined in the same crate, it's always
3141                         // accessible (since private entities can be made public)
3142                         // 2. if it's defined in another crate, it's accessible
3143                         // only if both the module is public and the entity is
3144                         // declared as public (due to pruning, we don't explore
3145                         // outside crate private modules => no need to check this)
3146                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3147                             candidates.push(ImportSuggestion { path: path });
3148                         }
3149                     }
3150                 }
3151
3152                 // collect submodules to explore
3153                 if let Some(module) = name_binding.module() {
3154                     // form the path
3155                     let mut path_segments = path_segments.clone();
3156                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3157
3158                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3159                         // add the module to the lookup
3160                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3161                         if seen_modules.insert(module.def_id().unwrap()) {
3162                             worklist.push((module, path_segments, is_extern));
3163                         }
3164                     }
3165                 }
3166             })
3167         }
3168
3169         candidates
3170     }
3171
3172     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3173         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3174         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3175             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3176         }
3177     }
3178
3179     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3180         match *vis {
3181             ast::Visibility::Public => ty::Visibility::Public,
3182             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3183             ast::Visibility::Inherited => {
3184                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3185             }
3186             ast::Visibility::Restricted { ref path, id } => {
3187                 let def = self.smart_resolve_path(id, None, path,
3188                                                   PathSource::Visibility).base_def();
3189                 if def == Def::Err {
3190                     ty::Visibility::Public
3191                 } else {
3192                     let vis = ty::Visibility::Restricted(def.def_id());
3193                     if self.is_accessible(vis) {
3194                         vis
3195                     } else {
3196                         self.session.span_err(path.span, "visibilities can only be restricted \
3197                                                           to ancestor modules");
3198                         ty::Visibility::Public
3199                     }
3200                 }
3201             }
3202         }
3203     }
3204
3205     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3206         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3207     }
3208
3209     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3210         vis.is_accessible_from(module.normal_ancestor_id, self)
3211     }
3212
3213     fn report_errors(&mut self) {
3214         self.report_shadowing_errors();
3215         let mut reported_spans = FxHashSet();
3216
3217         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3218             if !reported_spans.insert(span) { continue }
3219             let participle = |binding: &NameBinding| {
3220                 if binding.is_import() { "imported" } else { "defined" }
3221             };
3222             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3223             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3224             let note = if !lexical && b1.is_glob_import() {
3225                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3226             } else if let Def::Macro(..) = b1.def() {
3227                 format!("macro-expanded {} do not shadow",
3228                         if b1.is_import() { "macro imports" } else { "macros" })
3229             } else {
3230                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3231                         if b1.is_import() { "imports" } else { "items" })
3232             };
3233             if legacy {
3234                 let id = match b2.kind {
3235                     NameBindingKind::Import { directive, .. } => directive.id,
3236                     _ => unreachable!(),
3237                 };
3238                 let mut span = MultiSpan::from_span(span);
3239                 span.push_span_label(b1.span, msg1);
3240                 span.push_span_label(b2.span, msg2);
3241                 let msg = format!("`{}` is ambiguous", name);
3242                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3243             } else {
3244                 self.session.struct_span_err(span, &format!("`{}` is ambiguous", name))
3245                     .span_note(b1.span, &msg1)
3246                     .span_note(b2.span, &msg2)
3247                     .note(&note)
3248                     .emit();
3249             }
3250         }
3251
3252         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3253             if !reported_spans.insert(span) { continue }
3254             if binding.is_extern_crate() {
3255                 // Warn when using an inaccessible extern crate.
3256                 let node_id = match binding.kind {
3257                     NameBindingKind::Import { directive, .. } => directive.id,
3258                     _ => unreachable!(),
3259                 };
3260                 let msg = format!("extern crate `{}` is private", name);
3261                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3262             } else {
3263                 let def = binding.def();
3264                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3265             }
3266         }
3267     }
3268
3269     fn report_shadowing_errors(&mut self) {
3270         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3271             self.resolve_legacy_scope(scope, name, true);
3272         }
3273
3274         let mut reported_errors = FxHashSet();
3275         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3276             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3277                reported_errors.insert((binding.name, binding.span)) {
3278                 let msg = format!("`{}` is already in scope", binding.name);
3279                 self.session.struct_span_err(binding.span, &msg)
3280                     .note("macro-expanded `macro_rules!`s may not shadow \
3281                            existing macros (see RFC 1560)")
3282                     .emit();
3283             }
3284         }
3285     }
3286
3287     fn report_conflict(&mut self,
3288                        parent: Module,
3289                        ident: Ident,
3290                        ns: Namespace,
3291                        binding: &NameBinding,
3292                        old_binding: &NameBinding) {
3293         // Error on the second of two conflicting names
3294         if old_binding.span.lo > binding.span.lo {
3295             return self.report_conflict(parent, ident, ns, old_binding, binding);
3296         }
3297
3298         let container = match parent.kind {
3299             ModuleKind::Def(Def::Mod(_), _) => "module",
3300             ModuleKind::Def(Def::Trait(_), _) => "trait",
3301             ModuleKind::Block(..) => "block",
3302             _ => "enum",
3303         };
3304
3305         let (participle, noun) = match old_binding.is_import() {
3306             true => ("imported", "import"),
3307             false => ("defined", "definition"),
3308         };
3309
3310         let (name, span) = (ident.name, binding.span);
3311
3312         if let Some(s) = self.name_already_seen.get(&name) {
3313             if s == &span {
3314                 return;
3315             }
3316         }
3317
3318         let msg = {
3319             let kind = match (ns, old_binding.module()) {
3320                 (ValueNS, _) => "a value",
3321                 (MacroNS, _) => "a macro",
3322                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3323                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3324                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3325                 (TypeNS, _) => "a type",
3326             };
3327             format!("{} named `{}` has already been {} in this {}",
3328                     kind, name, participle, container)
3329         };
3330
3331         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3332             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3333             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3334                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3335                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3336             },
3337             _ => match (old_binding.is_import(), binding.is_import()) {
3338                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3339                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3340                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3341             },
3342         };
3343
3344         err.span_label(span, &format!("`{}` already {}", name, participle));
3345         if old_binding.span != syntax_pos::DUMMY_SP {
3346             err.span_label(old_binding.span, &format!("previous {} of `{}` here", noun, name));
3347         }
3348         err.emit();
3349         self.name_already_seen.insert(name, span);
3350     }
3351
3352     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3353         let (id, span) = (directive.id, directive.span);
3354         let msg = "`self` no longer imports values".to_string();
3355         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3356     }
3357
3358     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3359         if self.proc_macro_enabled { return; }
3360
3361         for attr in attrs {
3362             let maybe_binding = self.builtin_macros.get(&attr.name()).cloned().or_else(|| {
3363                 let ident = Ident::with_empty_ctxt(attr.name());
3364                 self.resolve_lexical_macro_path_segment(ident, MacroNS, None).ok()
3365             });
3366
3367             if let Some(binding) = maybe_binding {
3368                 if let SyntaxExtension::AttrProcMacro(..) = *binding.get_macro(self) {
3369                     attr::mark_known(attr);
3370
3371                     let msg = "attribute procedural macros are experimental";
3372                     let feature = "proc_macro";
3373
3374                     feature_err(&self.session.parse_sess, feature,
3375                                 attr.span, GateIssue::Language, msg)
3376                         .span_note(binding.span, "procedural macro imported here")
3377                         .emit();
3378                 }
3379             }
3380         }
3381     }
3382 }
3383
3384 fn is_struct_like(def: Def) -> bool {
3385     match def {
3386         Def::VariantCtor(_, CtorKind::Fictive) => true,
3387         _ => PathSource::Struct.is_expected(def),
3388     }
3389 }
3390
3391 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3392     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3393 }
3394
3395 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3396     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3397 }
3398
3399 fn names_to_string(idents: &[Ident]) -> String {
3400     let mut result = String::new();
3401     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3402         if i > 0 {
3403             result.push_str("::");
3404         }
3405         result.push_str(&ident.name.as_str());
3406     }
3407     result
3408 }
3409
3410 fn path_names_to_string(path: &Path) -> String {
3411     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3412 }
3413
3414 /// When an entity with a given name is not available in scope, we search for
3415 /// entities with that name in all crates. This method allows outputting the
3416 /// results of this search in a programmer-friendly way
3417 fn show_candidates(session: &mut DiagnosticBuilder,
3418                    candidates: &[ImportSuggestion],
3419                    better: bool) {
3420     // don't show more than MAX_CANDIDATES results, so
3421     // we're consistent with the trait suggestions
3422     const MAX_CANDIDATES: usize = 4;
3423
3424     // we want consistent results across executions, but candidates are produced
3425     // by iterating through a hash map, so make sure they are ordered:
3426     let mut path_strings: Vec<_> =
3427         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3428     path_strings.sort();
3429
3430     let better = if better { "better " } else { "" };
3431     let msg_diff = match path_strings.len() {
3432         1 => " is found in another module, you can import it",
3433         _ => "s are found in other modules, you can import them",
3434     };
3435
3436     let end = cmp::min(MAX_CANDIDATES, path_strings.len());
3437     session.help(&format!("possible {}candidate{} into scope:{}{}",
3438                           better,
3439                           msg_diff,
3440                           &path_strings[0..end].iter().map(|candidate| {
3441                               format!("\n  `use {};`", candidate)
3442                           }).collect::<String>(),
3443                           if path_strings.len() > MAX_CANDIDATES {
3444                               format!("\nand {} other candidates",
3445                                       path_strings.len() - MAX_CANDIDATES)
3446                           } else {
3447                               "".to_owned()
3448                           }
3449                           ));
3450 }
3451
3452 /// A somewhat inefficient routine to obtain the name of a module.
3453 fn module_to_string(module: Module) -> String {
3454     let mut names = Vec::new();
3455
3456     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3457         if let ModuleKind::Def(_, name) = module.kind {
3458             if let Some(parent) = module.parent {
3459                 names.push(Ident::with_empty_ctxt(name));
3460                 collect_mod(names, parent);
3461             }
3462         } else {
3463             // danger, shouldn't be ident?
3464             names.push(Ident::from_str("<opaque>"));
3465             collect_mod(names, module.parent.unwrap());
3466         }
3467     }
3468     collect_mod(&mut names, module);
3469
3470     if names.is_empty() {
3471         return "???".to_string();
3472     }
3473     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3474 }
3475
3476 fn err_path_resolution() -> PathResolution {
3477     PathResolution::new(Def::Err)
3478 }
3479
3480 #[derive(PartialEq,Copy, Clone)]
3481 pub enum MakeGlobMap {
3482     Yes,
3483     No,
3484 }
3485
3486 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }