src/librustc_resolve/lib.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 #![crate_name = "rustc_resolve"]
  12 #![crate_type = "dylib"]
  13 #![crate_type = "rlib"]
  14 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
  15       html_favicon_url = "https://doc.rust-lang.org/favicon.ico",
  16       html_root_url = "https://doc.rust-lang.org/nightly/")]
  17 #![deny(warnings)]
  18
  19 #![feature(associated_consts)]
  20 #![feature(rustc_diagnostic_macros)]
  21
  22 #![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
  23 #![cfg_attr(stage0, feature(rustc_private))]
  24 #![cfg_attr(stage0, feature(staged_api))]
  25
  26 #[macro_use]
  27 extern crate log;
  28 #[macro_use]
  29 extern crate syntax;
  30 extern crate syntax_pos;
  31 extern crate rustc_errors as errors;
  32 extern crate arena;
  33 #[macro_use]
  34 extern crate rustc;
  35
  36 use self::Namespace::*;
  37 use self::TypeParameters::*;
  38 use self::RibKind::*;
  39
  40 use rustc::hir::map::{Definitions, DefCollector};
  41 use rustc::hir::{self, PrimTy, TyBool, TyChar, TyFloat, TyInt, TyUint, TyStr};
  42 use rustc::middle::cstore::CrateLoader;
  43 use rustc::session::Session;
  44 use rustc::lint;
  45 use rustc::hir::def::*;
  46 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  47 use rustc::ty;
  48 use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
  49 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
  50
  51 use syntax::ext::hygiene::{Mark, SyntaxContext};
  52 use syntax::ast::{self, Name, NodeId, Ident, SpannedIdent, FloatTy, IntTy, UintTy};
  53 use syntax::ext::base::SyntaxExtension;
  54 use syntax::ext::base::Determinacy::{Determined, Undetermined};
  55 use syntax::ext::base::MacroKind;
  56 use syntax::symbol::{Symbol, keywords};
  57 use syntax::util::lev_distance::find_best_match_for_name;
  58
  59 use syntax::visit::{self, FnKind, Visitor};
  60 use syntax::attr;
  61 use syntax::ast::{Arm, BindingMode, Block, Crate, Expr, ExprKind};
  62 use syntax::ast::{FnDecl, ForeignItem, ForeignItemKind, Generics};
  63 use syntax::ast::{Item, ItemKind, ImplItem, ImplItemKind};
  64 use syntax::ast::{Local, Mutability, Pat, PatKind, Path};
  65 use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
  66 use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
  67
  68 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  69 use errors::DiagnosticBuilder;
  70
  71 use std::cell::{Cell, RefCell};
  72 use std::cmp;
  73 use std::collections::BTreeSet;
  74 use std::fmt;
  75 use std::mem::replace;
  76 use std::rc::Rc;
  77
  78 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
  79 use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
  80
  81 // NB: This module needs to be declared first so diagnostics are
  82 // registered before they are used.
  83 mod diagnostics;
  84
  85 mod macros;
  86 mod check_unused;
  87 mod build_reduced_graph;
  88 mod resolve_imports;
  89
  90 /// A free importable items suggested in case of resolution failure.
  91 struct ImportSuggestion {
  92     path: Path,
  93 }
  94
  95 /// A field or associated item from self type suggested in case of resolution failure.
  96 enum AssocSuggestion {
  97     Field,
  98     MethodWithSelf,
  99     AssocItem,
 100 }
 101
 102 #[derive(Eq)]
 103 struct BindingError {
 104     name: Name,
 105     origin: BTreeSet<Span>,
 106     target: BTreeSet<Span>,
 107 }
 108
 109 impl PartialOrd for BindingError {
 110     fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
 111         Some(self.cmp(other))
 112     }
 113 }
 114
 115 impl PartialEq for BindingError {
 116     fn eq(&self, other: &BindingError) -> bool {
 117         self.name == other.name
 118     }
 119 }
 120
 121 impl Ord for BindingError {
 122     fn cmp(&self, other: &BindingError) -> cmp::Ordering {
 123         self.name.cmp(&other.name)
 124     }
 125 }
 126
 127 enum ResolutionError<'a> {
 128     /// error E0401: can't use type parameters from outer function
 129     TypeParametersFromOuterFunction,
 130     /// error E0403: the name is already used for a type parameter in this type parameter list
 131     NameAlreadyUsedInTypeParameterList(Name, &'a Span),
 132     /// error E0407: method is not a member of trait
 133     MethodNotMemberOfTrait(Name, &'a str),
 134     /// error E0437: type is not a member of trait
 135     TypeNotMemberOfTrait(Name, &'a str),
 136     /// error E0438: const is not a member of trait
 137     ConstNotMemberOfTrait(Name, &'a str),
 138     /// error E0408: variable `{}` is not bound in all patterns
 139     VariableNotBoundInPattern(&'a BindingError),
 140     /// error E0409: variable `{}` is bound in inconsistent ways within the same match arm
 141     VariableBoundWithDifferentMode(Name, Span),
 142     /// error E0415: identifier is bound more than once in this parameter list
 143     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 144     /// error E0416: identifier is bound more than once in the same pattern
 145     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 146     /// error E0426: use of undeclared label
 147     UndeclaredLabel(&'a str),
 148     /// error E0429: `self` imports are only allowed within a { } list
 149     SelfImportsOnlyAllowedWithin,
 150     /// error E0430: `self` import can only appear once in the list
 151     SelfImportCanOnlyAppearOnceInTheList,
 152     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 153     SelfImportOnlyInImportListWithNonEmptyPrefix,
 154     /// error E0432: unresolved import
 155     UnresolvedImport(Option<(&'a str, &'a str)>),
 156     /// error E0433: failed to resolve
 157     FailedToResolve(&'a str),
 158     /// error E0434: can't capture dynamic environment in a fn item
 159     CannotCaptureDynamicEnvironmentInFnItem,
 160     /// error E0435: attempt to use a non-constant value in a constant
 161     AttemptToUseNonConstantValueInConstant,
 162     /// error E0530: X bindings cannot shadow Ys
 163     BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
 164     /// error E0128: type parameters with a default cannot use forward declared identifiers
 165     ForwardDeclaredTyParam,
 166 }
 167
 168 fn resolve_error<'sess, 'a>(resolver: &'sess Resolver,
 169                             span: Span,
 170                             resolution_error: ResolutionError<'a>) {
 171     resolve_struct_error(resolver, span, resolution_error).emit();
 172 }
 173
 174 fn resolve_struct_error<'sess, 'a>(resolver: &'sess Resolver,
 175                                    span: Span,
 176                                    resolution_error: ResolutionError<'a>)
 177                                    -> DiagnosticBuilder<'sess> {
 178     match resolution_error {
 179         ResolutionError::TypeParametersFromOuterFunction => {
 180             let mut err = struct_span_err!(resolver.session,
 181                                            span,
 182                                            E0401,
 183                                            "can't use type parameters from outer function; \
 184                                            try using a local type parameter instead");
 185             err.span_label(span, "use of type variable from outer function");
 186             err
 187         }
 188         ResolutionError::NameAlreadyUsedInTypeParameterList(name, first_use_span) => {
 189              let mut err = struct_span_err!(resolver.session,
 190                                             span,
 191                                             E0403,
 192                                             "the name `{}` is already used for a type parameter \
 193                                             in this type parameter list",
 194                                             name);
 195              err.span_label(span, "already used");
 196              err.span_label(first_use_span.clone(), format!("first use of `{}`", name));
 197              err
 198         }
 199         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 200             let mut err = struct_span_err!(resolver.session,
 201                                            span,
 202                                            E0407,
 203                                            "method `{}` is not a member of trait `{}`",
 204                                            method,
 205                                            trait_);
 206             err.span_label(span, format!("not a member of trait `{}`", trait_));
 207             err
 208         }
 209         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 210             let mut err = struct_span_err!(resolver.session,
 211                              span,
 212                              E0437,
 213                              "type `{}` is not a member of trait `{}`",
 214                              type_,
 215                              trait_);
 216             err.span_label(span, format!("not a member of trait `{}`", trait_));
 217             err
 218         }
 219         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 220             let mut err = struct_span_err!(resolver.session,
 221                              span,
 222                              E0438,
 223                              "const `{}` is not a member of trait `{}`",
 224                              const_,
 225                              trait_);
 226             err.span_label(span, format!("not a member of trait `{}`", trait_));
 227             err
 228         }
 229         ResolutionError::VariableNotBoundInPattern(binding_error) => {
 230             let target_sp = binding_error.target.iter().map(|x| *x).collect::<Vec<_>>();
 231             let msp = MultiSpan::from_spans(target_sp.clone());
 232             let msg = format!("variable `{}` is not bound in all patterns", binding_error.name);
 233             let mut err = resolver.session.struct_span_err_with_code(msp, &msg, "E0408");
 234             for sp in target_sp {
 235                 err.span_label(sp, format!("pattern doesn't bind `{}`", binding_error.name));
 236             }
 237             let origin_sp = binding_error.origin.iter().map(|x| *x).collect::<Vec<_>>();
 238             for sp in origin_sp {
 239                 err.span_label(sp, "variable not in all patterns");
 240             }
 241             err
 242         }
 243         ResolutionError::VariableBoundWithDifferentMode(variable_name,
 244                                                         first_binding_span) => {
 245             let mut err = struct_span_err!(resolver.session,
 246                              span,
 247                              E0409,
 248                              "variable `{}` is bound in inconsistent \
 249                              ways within the same match arm",
 250                              variable_name);
 251             err.span_label(span, "bound in different ways");
 252             err.span_label(first_binding_span, "first binding");
 253             err
 254         }
 255         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 256             let mut err = struct_span_err!(resolver.session,
 257                              span,
 258                              E0415,
 259                              "identifier `{}` is bound more than once in this parameter list",
 260                              identifier);
 261             err.span_label(span, "used as parameter more than once");
 262             err
 263         }
 264         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 265             let mut err = struct_span_err!(resolver.session,
 266                              span,
 267                              E0416,
 268                              "identifier `{}` is bound more than once in the same pattern",
 269                              identifier);
 270             err.span_label(span, "used in a pattern more than once");
 271             err
 272         }
 273         ResolutionError::UndeclaredLabel(name) => {
 274             let mut err = struct_span_err!(resolver.session,
 275                                            span,
 276                                            E0426,
 277                                            "use of undeclared label `{}`",
 278                                            name);
 279             err.span_label(span, format!("undeclared label `{}`", name));
 280             err
 281         }
 282         ResolutionError::SelfImportsOnlyAllowedWithin => {
 283             struct_span_err!(resolver.session,
 284                              span,
 285                              E0429,
 286                              "{}",
 287                              "`self` imports are only allowed within a { } list")
 288         }
 289         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 290             struct_span_err!(resolver.session,
 291                              span,
 292                              E0430,
 293                              "`self` import can only appear once in the list")
 294         }
 295         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 296             struct_span_err!(resolver.session,
 297                              span,
 298                              E0431,
 299                              "`self` import can only appear in an import list with a \
 300                               non-empty prefix")
 301         }
 302         ResolutionError::UnresolvedImport(name) => {
 303             let msg = match name {
 304                 Some((n, _)) => format!("unresolved import `{}`", n),
 305                 None => "unresolved import".to_owned(),
 306             };
 307             let mut err = struct_span_err!(resolver.session, span, E0432, "{}", msg);
 308             if let Some((_, p)) = name {
 309                 err.span_label(span, p);
 310             }
 311             err
 312         }
 313         ResolutionError::FailedToResolve(msg) => {
 314             let mut err = struct_span_err!(resolver.session, span, E0433,
 315                                            "failed to resolve. {}", msg);
 316             err.span_label(span, msg);
 317             err
 318         }
 319         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 320             struct_span_err!(resolver.session,
 321                              span,
 322                              E0434,
 323                              "{}",
 324                              "can't capture dynamic environment in a fn item; use the || { ... } \
 325                               closure form instead")
 326         }
 327         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 328             let mut err = struct_span_err!(resolver.session,
 329                              span,
 330                              E0435,
 331                              "attempt to use a non-constant value in a constant");
 332             err.span_label(span, "non-constant used with constant");
 333             err
 334         }
 335         ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
 336             let shadows_what = PathResolution::new(binding.def()).kind_name();
 337             let mut err = struct_span_err!(resolver.session,
 338                                            span,
 339                                            E0530,
 340                                            "{}s cannot shadow {}s", what_binding, shadows_what);
 341             err.span_label(span, format!("cannot be named the same as a {}", shadows_what));
 342             let participle = if binding.is_import() { "imported" } else { "defined" };
 343             let msg = format!("a {} `{}` is {} here", shadows_what, name, participle);
 344             err.span_label(binding.span, msg);
 345             err
 346         }
 347         ResolutionError::ForwardDeclaredTyParam => {
 348             let mut err = struct_span_err!(resolver.session, span, E0128,
 349                                            "type parameters with a default cannot use \
 350                                             forward declared identifiers");
 351             err.span_label(span, format!("defaulted type parameters \
 352                                            cannot be forward declared"));
 353             err
 354         }
 355     }
 356 }
 357
 358 #[derive(Copy, Clone, Debug)]
 359 struct BindingInfo {
 360     span: Span,
 361     binding_mode: BindingMode,
 362 }
 363
 364 // Map from the name in a pattern to its binding mode.
 365 type BindingMap = FxHashMap<Ident, BindingInfo>;
 366
 367 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 368 enum PatternSource {
 369     Match,
 370     IfLet,
 371     WhileLet,
 372     Let,
 373     For,
 374     FnParam,
 375 }
 376
 377 impl PatternSource {
 378     fn is_refutable(self) -> bool {
 379         match self {
 380             PatternSource::Match | PatternSource::IfLet | PatternSource::WhileLet => true,
 381             PatternSource::Let | PatternSource::For | PatternSource::FnParam  => false,
 382         }
 383     }
 384     fn descr(self) -> &'static str {
 385         match self {
 386             PatternSource::Match => "match binding",
 387             PatternSource::IfLet => "if let binding",
 388             PatternSource::WhileLet => "while let binding",
 389             PatternSource::Let => "let binding",
 390             PatternSource::For => "for binding",
 391             PatternSource::FnParam => "function parameter",
 392         }
 393     }
 394 }
 395
 396 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 397 enum PathSource<'a> {
 398     // Type paths `Path`.
 399     Type,
 400     // Trait paths in bounds or impls.
 401     Trait,
 402     // Expression paths `path`, with optional parent context.
 403     Expr(Option<&'a Expr>),
 404     // Paths in path patterns `Path`.
 405     Pat,
 406     // Paths in struct expressions and patterns `Path { .. }`.
 407     Struct,
 408     // Paths in tuple struct patterns `Path(..)`.
 409     TupleStruct,
 410     // `m::A::B` in `<T as m::A>::B::C`.
 411     TraitItem(Namespace),
 412     // Path in `pub(path)`
 413     Visibility,
 414     // Path in `use a::b::{...};`
 415     ImportPrefix,
 416 }
 417
 418 impl<'a> PathSource<'a> {
 419     fn namespace(self) -> Namespace {
 420         match self {
 421             PathSource::Type | PathSource::Trait | PathSource::Struct |
 422             PathSource::Visibility | PathSource::ImportPrefix => TypeNS,
 423             PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
 424             PathSource::TraitItem(ns) => ns,
 425         }
 426     }
 427
 428     fn global_by_default(self) -> bool {
 429         match self {
 430             PathSource::Visibility | PathSource::ImportPrefix => true,
 431             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 432             PathSource::Struct | PathSource::TupleStruct |
 433             PathSource::Trait | PathSource::TraitItem(..) => false,
 434         }
 435     }
 436
 437     fn defer_to_typeck(self) -> bool {
 438         match self {
 439             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 440             PathSource::Struct | PathSource::TupleStruct => true,
 441             PathSource::Trait | PathSource::TraitItem(..) |
 442             PathSource::Visibility | PathSource::ImportPrefix => false,
 443         }
 444     }
 445
 446     fn descr_expected(self) -> &'static str {
 447         match self {
 448             PathSource::Type => "type",
 449             PathSource::Trait => "trait",
 450             PathSource::Pat => "unit struct/variant or constant",
 451             PathSource::Struct => "struct, variant or union type",
 452             PathSource::TupleStruct => "tuple struct/variant",
 453             PathSource::Visibility => "module",
 454             PathSource::ImportPrefix => "module or enum",
 455             PathSource::TraitItem(ns) => match ns {
 456                 TypeNS => "associated type",
 457                 ValueNS => "method or associated constant",
 458                 MacroNS => bug!("associated macro"),
 459             },
 460             PathSource::Expr(parent) => match parent.map(|p| &p.node) {
 461                 // "function" here means "anything callable" rather than `Def::Fn`,
 462                 // this is not precise but usually more helpful than just "value".
 463                 Some(&ExprKind::Call(..)) => "function",
 464                 _ => "value",
 465             },
 466         }
 467     }
 468
 469     fn is_expected(self, def: Def) -> bool {
 470         match self {
 471             PathSource::Type => match def {
 472                 Def::Struct(..) | Def::Union(..) | Def::Enum(..) |
 473                 Def::Trait(..) | Def::TyAlias(..) | Def::AssociatedTy(..) |
 474                 Def::PrimTy(..) | Def::TyParam(..) | Def::SelfTy(..) => true,
 475                 _ => false,
 476             },
 477             PathSource::Trait => match def {
 478                 Def::Trait(..) => true,
 479                 _ => false,
 480             },
 481             PathSource::Expr(..) => match def {
 482                 Def::StructCtor(_, CtorKind::Const) | Def::StructCtor(_, CtorKind::Fn) |
 483                 Def::VariantCtor(_, CtorKind::Const) | Def::VariantCtor(_, CtorKind::Fn) |
 484                 Def::Const(..) | Def::Static(..) | Def::Local(..) | Def::Upvar(..) |
 485                 Def::Fn(..) | Def::Method(..) | Def::AssociatedConst(..) => true,
 486                 _ => false,
 487             },
 488             PathSource::Pat => match def {
 489                 Def::StructCtor(_, CtorKind::Const) |
 490                 Def::VariantCtor(_, CtorKind::Const) |
 491                 Def::Const(..) | Def::AssociatedConst(..) => true,
 492                 _ => false,
 493             },
 494             PathSource::TupleStruct => match def {
 495                 Def::StructCtor(_, CtorKind::Fn) | Def::VariantCtor(_, CtorKind::Fn) => true,
 496                 _ => false,
 497             },
 498             PathSource::Struct => match def {
 499                 Def::Struct(..) | Def::Union(..) | Def::Variant(..) |
 500                 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => true,
 501                 _ => false,
 502             },
 503             PathSource::TraitItem(ns) => match def {
 504                 Def::AssociatedConst(..) | Def::Method(..) if ns == ValueNS => true,
 505                 Def::AssociatedTy(..) if ns == TypeNS => true,
 506                 _ => false,
 507             },
 508             PathSource::ImportPrefix => match def {
 509                 Def::Mod(..) | Def::Enum(..) => true,
 510                 _ => false,
 511             },
 512             PathSource::Visibility => match def {
 513                 Def::Mod(..) => true,
 514                 _ => false,
 515             },
 516         }
 517     }
 518
 519     fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
 520         __diagnostic_used!(E0404);
 521         __diagnostic_used!(E0405);
 522         __diagnostic_used!(E0412);
 523         __diagnostic_used!(E0422);
 524         __diagnostic_used!(E0423);
 525         __diagnostic_used!(E0425);
 526         __diagnostic_used!(E0531);
 527         __diagnostic_used!(E0532);
 528         __diagnostic_used!(E0573);
 529         __diagnostic_used!(E0574);
 530         __diagnostic_used!(E0575);
 531         __diagnostic_used!(E0576);
 532         __diagnostic_used!(E0577);
 533         __diagnostic_used!(E0578);
 534         match (self, has_unexpected_resolution) {
 535             (PathSource::Trait, true) => "E0404",
 536             (PathSource::Trait, false) => "E0405",
 537             (PathSource::Type, true) => "E0573",
 538             (PathSource::Type, false) => "E0412",
 539             (PathSource::Struct, true) => "E0574",
 540             (PathSource::Struct, false) => "E0422",
 541             (PathSource::Expr(..), true) => "E0423",
 542             (PathSource::Expr(..), false) => "E0425",
 543             (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
 544             (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
 545             (PathSource::TraitItem(..), true) => "E0575",
 546             (PathSource::TraitItem(..), false) => "E0576",
 547             (PathSource::Visibility, true) | (PathSource::ImportPrefix, true) => "E0577",
 548             (PathSource::Visibility, false) | (PathSource::ImportPrefix, false) => "E0578",
 549         }
 550     }
 551 }
 552
 553 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 554 pub enum Namespace {
 555     TypeNS,
 556     ValueNS,
 557     MacroNS,
 558 }
 559
 560 #[derive(Clone, Default, Debug)]
 561 pub struct PerNS<T> {
 562     value_ns: T,
 563     type_ns: T,
 564     macro_ns: Option<T>,
 565 }
 566
 567 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
 568     type Output = T;
 569     fn index(&self, ns: Namespace) -> &T {
 570         match ns {
 571             ValueNS => &self.value_ns,
 572             TypeNS => &self.type_ns,
 573             MacroNS => self.macro_ns.as_ref().unwrap(),
 574         }
 575     }
 576 }
 577
 578 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
 579     fn index_mut(&mut self, ns: Namespace) -> &mut T {
 580         match ns {
 581             ValueNS => &mut self.value_ns,
 582             TypeNS => &mut self.type_ns,
 583             MacroNS => self.macro_ns.as_mut().unwrap(),
 584         }
 585     }
 586 }
 587
 588 impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
 589     fn visit_item(&mut self, item: &'tcx Item) {
 590         self.resolve_item(item);
 591     }
 592     fn visit_arm(&mut self, arm: &'tcx Arm) {
 593         self.resolve_arm(arm);
 594     }
 595     fn visit_block(&mut self, block: &'tcx Block) {
 596         self.resolve_block(block);
 597     }
 598     fn visit_expr(&mut self, expr: &'tcx Expr) {
 599         self.resolve_expr(expr, None);
 600     }
 601     fn visit_local(&mut self, local: &'tcx Local) {
 602         self.resolve_local(local);
 603     }
 604     fn visit_ty(&mut self, ty: &'tcx Ty) {
 605         if let TyKind::Path(ref qself, ref path) = ty.node {
 606             self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
 607         } else if let TyKind::ImplicitSelf = ty.node {
 608             let self_ty = keywords::SelfType.ident();
 609             let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, true, ty.span)
 610                           .map_or(Def::Err, |d| d.def());
 611             self.record_def(ty.id, PathResolution::new(def));
 612         } else if let TyKind::Array(ref element, ref length) = ty.node {
 613             self.visit_ty(element);
 614             self.with_constant_rib(|this| {
 615                 this.visit_expr(length);
 616             });
 617             return;
 618         }
 619         visit::walk_ty(self, ty);
 620     }
 621     fn visit_poly_trait_ref(&mut self,
 622                             tref: &'tcx ast::PolyTraitRef,
 623                             m: &'tcx ast::TraitBoundModifier) {
 624         self.smart_resolve_path(tref.trait_ref.ref_id, None,
 625                                 &tref.trait_ref.path, PathSource::Trait);
 626         visit::walk_poly_trait_ref(self, tref, m);
 627     }
 628     fn visit_variant(&mut self,
 629                      variant: &'tcx ast::Variant,
 630                      generics: &'tcx Generics,
 631                      item_id: ast::NodeId) {
 632         if let Some(ref dis_expr) = variant.node.disr_expr {
 633             // resolve the discriminator expr as a constant
 634             self.with_constant_rib(|this| {
 635                 this.visit_expr(dis_expr);
 636             });
 637         }
 638
 639         // `visit::walk_variant` without the discriminant expression.
 640         self.visit_variant_data(&variant.node.data,
 641                                 variant.node.name,
 642                                 generics,
 643                                 item_id,
 644                                 variant.span);
 645     }
 646     fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
 647         let type_parameters = match foreign_item.node {
 648             ForeignItemKind::Fn(_, ref generics) => {
 649                 HasTypeParameters(generics, ItemRibKind)
 650             }
 651             ForeignItemKind::Static(..) => NoTypeParameters,
 652         };
 653         self.with_type_parameter_rib(type_parameters, |this| {
 654             visit::walk_foreign_item(this, foreign_item);
 655         });
 656     }
 657     fn visit_fn(&mut self,
 658                 function_kind: FnKind<'tcx>,
 659                 declaration: &'tcx FnDecl,
 660                 _: Span,
 661                 node_id: NodeId) {
 662         let rib_kind = match function_kind {
 663             FnKind::ItemFn(_, generics, ..) => {
 664                 self.visit_generics(generics);
 665                 ItemRibKind
 666             }
 667             FnKind::Method(_, sig, _, _) => {
 668                 self.visit_generics(&sig.generics);
 669                 MethodRibKind(!sig.decl.has_self())
 670             }
 671             FnKind::Closure(_) => ClosureRibKind(node_id),
 672         };
 673
 674         // Create a value rib for the function.
 675         self.ribs[ValueNS].push(Rib::new(rib_kind));
 676
 677         // Create a label rib for the function.
 678         self.label_ribs.push(Rib::new(rib_kind));
 679
 680         // Add each argument to the rib.
 681         let mut bindings_list = FxHashMap();
 682         for argument in &declaration.inputs {
 683             self.resolve_pattern(&argument.pat, PatternSource::FnParam, &mut bindings_list);
 684
 685             self.visit_ty(&argument.ty);
 686
 687             debug!("(resolving function) recorded argument");
 688         }
 689         visit::walk_fn_ret_ty(self, &declaration.output);
 690
 691         // Resolve the function body.
 692         match function_kind {
 693             FnKind::ItemFn(.., body) |
 694             FnKind::Method(.., body) => {
 695                 self.visit_block(body);
 696             }
 697             FnKind::Closure(body) => {
 698                 self.visit_expr(body);
 699             }
 700         };
 701
 702         debug!("(resolving function) leaving function");
 703
 704         self.label_ribs.pop();
 705         self.ribs[ValueNS].pop();
 706     }
 707     fn visit_generics(&mut self, generics: &'tcx Generics) {
 708         // For type parameter defaults, we have to ban access
 709         // to following type parameters, as the Substs can only
 710         // provide previous type parameters as they're built.
 711         let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
 712         default_ban_rib.bindings.extend(generics.ty_params.iter()
 713             .skip_while(|p| p.default.is_none())
 714             .map(|p| (Ident::with_empty_ctxt(p.ident.name), Def::Err)));
 715
 716         for param in &generics.ty_params {
 717             for bound in &param.bounds {
 718                 self.visit_ty_param_bound(bound);
 719             }
 720
 721             if let Some(ref ty) = param.default {
 722                 self.ribs[TypeNS].push(default_ban_rib);
 723                 self.visit_ty(ty);
 724                 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
 725             }
 726
 727             // Allow all following defaults to refer to this type parameter.
 728             default_ban_rib.bindings.remove(&Ident::with_empty_ctxt(param.ident.name));
 729         }
 730         for lt in &generics.lifetimes { self.visit_lifetime_def(lt); }
 731         for p in &generics.where_clause.predicates { self.visit_where_predicate(p); }
 732     }
 733 }
 734
 735 pub type ErrorMessage = Option<(Span, String)>;
 736
 737 #[derive(Copy, Clone)]
 738 enum TypeParameters<'a, 'b> {
 739     NoTypeParameters,
 740     HasTypeParameters(// Type parameters.
 741                       &'b Generics,
 742
 743                       // The kind of the rib used for type parameters.
 744                       RibKind<'a>),
 745 }
 746
 747 // The rib kind controls the translation of local
 748 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 749 #[derive(Copy, Clone, Debug)]
 750 enum RibKind<'a> {
 751     // No translation needs to be applied.
 752     NormalRibKind,
 753
 754     // We passed through a closure scope at the given node ID.
 755     // Translate upvars as appropriate.
 756     ClosureRibKind(NodeId /* func id */),
 757
 758     // We passed through an impl or trait and are now in one of its
 759     // methods. Allow references to ty params that impl or trait
 760     // binds. Disallow any other upvars (including other ty params that are
 761     // upvars).
 762     //
 763     // The boolean value represents the fact that this method is static or not.
 764     MethodRibKind(bool),
 765
 766     // We passed through an item scope. Disallow upvars.
 767     ItemRibKind,
 768
 769     // We're in a constant item. Can't refer to dynamic stuff.
 770     ConstantItemRibKind,
 771
 772     // We passed through a module.
 773     ModuleRibKind(Module<'a>),
 774
 775     // We passed through a `macro_rules!` statement
 776     MacroDefinition(DefId),
 777
 778     // All bindings in this rib are type parameters that can't be used
 779     // from the default of a type parameter because they're not declared
 780     // before said type parameter. Also see the `visit_generics` override.
 781     ForwardTyParamBanRibKind,
 782 }
 783
 784 /// One local scope.
 785 #[derive(Debug)]
 786 struct Rib<'a> {
 787     bindings: FxHashMap<Ident, Def>,
 788     kind: RibKind<'a>,
 789 }
 790
 791 impl<'a> Rib<'a> {
 792     fn new(kind: RibKind<'a>) -> Rib<'a> {
 793         Rib {
 794             bindings: FxHashMap(),
 795             kind: kind,
 796         }
 797     }
 798 }
 799
 800 enum LexicalScopeBinding<'a> {
 801     Item(&'a NameBinding<'a>),
 802     Def(Def),
 803 }
 804
 805 impl<'a> LexicalScopeBinding<'a> {
 806     fn item(self) -> Option<&'a NameBinding<'a>> {
 807         match self {
 808             LexicalScopeBinding::Item(binding) => Some(binding),
 809             _ => None,
 810         }
 811     }
 812
 813     fn def(self) -> Def {
 814         match self {
 815             LexicalScopeBinding::Item(binding) => binding.def(),
 816             LexicalScopeBinding::Def(def) => def,
 817         }
 818     }
 819 }
 820
 821 #[derive(Clone)]
 822 enum PathResult<'a> {
 823     Module(Module<'a>),
 824     NonModule(PathResolution),
 825     Indeterminate,
 826     Failed(String, bool /* is the error from the last segment? */),
 827 }
 828
 829 enum ModuleKind {
 830     Block(NodeId),
 831     Def(Def, Name),
 832 }
 833
 834 /// One node in the tree of modules.
 835 pub struct ModuleData<'a> {
 836     parent: Option<Module<'a>>,
 837     kind: ModuleKind,
 838
 839     // The def id of the closest normal module (`mod`) ancestor (including this module).
 840     normal_ancestor_id: DefId,
 841
 842     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
 843     legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, Span, MacroKind)>>,
 844     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 845
 846     // Macro invocations that can expand into items in this module.
 847     unresolved_invocations: RefCell<FxHashSet<Mark>>,
 848
 849     no_implicit_prelude: bool,
 850
 851     glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
 852     globs: RefCell<Vec<&'a ImportDirective<'a>>>,
 853
 854     // Used to memoize the traits in this module for faster searches through all traits in scope.
 855     traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
 856
 857     // Whether this module is populated. If not populated, any attempt to
 858     // access the children must be preceded with a
 859     // `populate_module_if_necessary` call.
 860     populated: Cell<bool>,
 861
 862     /// Span of the module itself. Used for error reporting.
 863     span: Span,
 864 }
 865
 866 pub type Module<'a> = &'a ModuleData<'a>;
 867
 868 impl<'a> ModuleData<'a> {
 869     fn new(parent: Option<Module<'a>>,
 870            kind: ModuleKind,
 871            normal_ancestor_id: DefId,
 872            span: Span) -> Self {
 873         ModuleData {
 874             parent: parent,
 875             kind: kind,
 876             normal_ancestor_id: normal_ancestor_id,
 877             resolutions: RefCell::new(FxHashMap()),
 878             legacy_macro_resolutions: RefCell::new(Vec::new()),
 879             macro_resolutions: RefCell::new(Vec::new()),
 880             unresolved_invocations: RefCell::new(FxHashSet()),
 881             no_implicit_prelude: false,
 882             glob_importers: RefCell::new(Vec::new()),
 883             globs: RefCell::new((Vec::new())),
 884             traits: RefCell::new(None),
 885             populated: Cell::new(normal_ancestor_id.is_local()),
 886             span: span,
 887         }
 888     }
 889
 890     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 891         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 892             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 893         }
 894     }
 895
 896     fn def(&self) -> Option<Def> {
 897         match self.kind {
 898             ModuleKind::Def(def, _) => Some(def),
 899             _ => None,
 900         }
 901     }
 902
 903     fn def_id(&self) -> Option<DefId> {
 904         self.def().as_ref().map(Def::def_id)
 905     }
 906
 907     // `self` resolves to the first module ancestor that `is_normal`.
 908     fn is_normal(&self) -> bool {
 909         match self.kind {
 910             ModuleKind::Def(Def::Mod(_), _) => true,
 911             _ => false,
 912         }
 913     }
 914
 915     fn is_trait(&self) -> bool {
 916         match self.kind {
 917             ModuleKind::Def(Def::Trait(_), _) => true,
 918             _ => false,
 919         }
 920     }
 921
 922     fn is_local(&self) -> bool {
 923         self.normal_ancestor_id.is_local()
 924     }
 925
 926     fn nearest_item_scope(&'a self) -> Module<'a> {
 927         if self.is_trait() { self.parent.unwrap() } else { self }
 928     }
 929 }
 930
 931 impl<'a> fmt::Debug for ModuleData<'a> {
 932     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 933         write!(f, "{:?}", self.def())
 934     }
 935 }
 936
 937 // Records a possibly-private value, type, or module definition.
 938 #[derive(Clone, Debug)]
 939 pub struct NameBinding<'a> {
 940     kind: NameBindingKind<'a>,
 941     expansion: Mark,
 942     span: Span,
 943     vis: ty::Visibility,
 944 }
 945
 946 pub trait ToNameBinding<'a> {
 947     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 948 }
 949
 950 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 951     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 952         self
 953     }
 954 }
 955
 956 #[derive(Clone, Debug)]
 957 enum NameBindingKind<'a> {
 958     Def(Def),
 959     Module(Module<'a>),
 960     Import {
 961         binding: &'a NameBinding<'a>,
 962         directive: &'a ImportDirective<'a>,
 963         used: Cell<bool>,
 964         legacy_self_import: bool,
 965     },
 966     Ambiguity {
 967         b1: &'a NameBinding<'a>,
 968         b2: &'a NameBinding<'a>,
 969         legacy: bool,
 970     }
 971 }
 972
 973 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 974
 975 struct AmbiguityError<'a> {
 976     span: Span,
 977     name: Name,
 978     lexical: bool,
 979     b1: &'a NameBinding<'a>,
 980     b2: &'a NameBinding<'a>,
 981     legacy: bool,
 982 }
 983
 984 impl<'a> NameBinding<'a> {
 985     fn module(&self) -> Option<Module<'a>> {
 986         match self.kind {
 987             NameBindingKind::Module(module) => Some(module),
 988             NameBindingKind::Import { binding, .. } => binding.module(),
 989             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 990             _ => None,
 991         }
 992     }
 993
 994     fn def(&self) -> Def {
 995         match self.kind {
 996             NameBindingKind::Def(def) => def,
 997             NameBindingKind::Module(module) => module.def().unwrap(),
 998             NameBindingKind::Import { binding, .. } => binding.def(),
 999             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1000             NameBindingKind::Ambiguity { .. } => Def::Err,
1001         }
1002     }
1003
1004     fn def_ignoring_ambiguity(&self) -> Def {
1005         match self.kind {
1006             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1007             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1008             _ => self.def(),
1009         }
1010     }
1011
1012     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1013         resolver.get_macro(self.def_ignoring_ambiguity())
1014     }
1015
1016     // We sometimes need to treat variants as `pub` for backwards compatibility
1017     fn pseudo_vis(&self) -> ty::Visibility {
1018         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1019     }
1020
1021     fn is_variant(&self) -> bool {
1022         match self.kind {
1023             NameBindingKind::Def(Def::Variant(..)) |
1024             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1025             _ => false,
1026         }
1027     }
1028
1029     fn is_extern_crate(&self) -> bool {
1030         match self.kind {
1031             NameBindingKind::Import {
1032                 directive: &ImportDirective {
1033                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1034                 }, ..
1035             } => true,
1036             _ => false,
1037         }
1038     }
1039
1040     fn is_import(&self) -> bool {
1041         match self.kind {
1042             NameBindingKind::Import { .. } => true,
1043             _ => false,
1044         }
1045     }
1046
1047     fn is_glob_import(&self) -> bool {
1048         match self.kind {
1049             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1050             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1051             _ => false,
1052         }
1053     }
1054
1055     fn is_importable(&self) -> bool {
1056         match self.def() {
1057             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1058             _ => true,
1059         }
1060     }
1061 }
1062
1063 /// Interns the names of the primitive types.
1064 struct PrimitiveTypeTable {
1065     primitive_types: FxHashMap<Name, PrimTy>,
1066 }
1067
1068 impl PrimitiveTypeTable {
1069     fn new() -> PrimitiveTypeTable {
1070         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1071
1072         table.intern("bool", TyBool);
1073         table.intern("char", TyChar);
1074         table.intern("f32", TyFloat(FloatTy::F32));
1075         table.intern("f64", TyFloat(FloatTy::F64));
1076         table.intern("isize", TyInt(IntTy::Is));
1077         table.intern("i8", TyInt(IntTy::I8));
1078         table.intern("i16", TyInt(IntTy::I16));
1079         table.intern("i32", TyInt(IntTy::I32));
1080         table.intern("i64", TyInt(IntTy::I64));
1081         table.intern("i128", TyInt(IntTy::I128));
1082         table.intern("str", TyStr);
1083         table.intern("usize", TyUint(UintTy::Us));
1084         table.intern("u8", TyUint(UintTy::U8));
1085         table.intern("u16", TyUint(UintTy::U16));
1086         table.intern("u32", TyUint(UintTy::U32));
1087         table.intern("u64", TyUint(UintTy::U64));
1088         table.intern("u128", TyUint(UintTy::U128));
1089         table
1090     }
1091
1092     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1093         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1094     }
1095 }
1096
1097 /// The main resolver class.
1098 pub struct Resolver<'a> {
1099     session: &'a Session,
1100
1101     pub definitions: Definitions,
1102
1103     graph_root: Module<'a>,
1104
1105     prelude: Option<Module<'a>>,
1106
1107     trait_item_map: FxHashMap<(DefId, Name, Namespace), (Def, bool /* has self */)>,
1108
1109     // Names of fields of an item `DefId` accessible with dot syntax.
1110     // Used for hints during error reporting.
1111     field_names: FxHashMap<DefId, Vec<Name>>,
1112
1113     // All imports known to succeed or fail.
1114     determined_imports: Vec<&'a ImportDirective<'a>>,
1115
1116     // All non-determined imports.
1117     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1118
1119     // The module that represents the current item scope.
1120     current_module: Module<'a>,
1121
1122     // The current set of local scopes for types and values.
1123     // FIXME #4948: Reuse ribs to avoid allocation.
1124     ribs: PerNS<Vec<Rib<'a>>>,
1125
1126     // The current set of local scopes, for labels.
1127     label_ribs: Vec<Rib<'a>>,
1128
1129     // The trait that the current context can refer to.
1130     current_trait_ref: Option<(DefId, TraitRef)>,
1131
1132     // The current self type if inside an impl (used for better errors).
1133     current_self_type: Option<Ty>,
1134
1135     // The idents for the primitive types.
1136     primitive_type_table: PrimitiveTypeTable,
1137
1138     def_map: DefMap,
1139     pub freevars: FreevarMap,
1140     freevars_seen: NodeMap<NodeMap<usize>>,
1141     pub export_map: ExportMap,
1142     pub trait_map: TraitMap,
1143
1144     // A map from nodes to anonymous modules.
1145     // Anonymous modules are pseudo-modules that are implicitly created around items
1146     // contained within blocks.
1147     //
1148     // For example, if we have this:
1149     //
1150     //  fn f() {
1151     //      fn g() {
1152     //          ...
1153     //      }
1154     //  }
1155     //
1156     // There will be an anonymous module created around `g` with the ID of the
1157     // entry block for `f`.
1158     block_map: NodeMap<Module<'a>>,
1159     module_map: FxHashMap<DefId, Module<'a>>,
1160     extern_crate_roots: FxHashMap<(CrateNum, bool /* MacrosOnly? */), Module<'a>>,
1161
1162     pub make_glob_map: bool,
1163     // Maps imports to the names of items actually imported (this actually maps
1164     // all imports, but only glob imports are actually interesting).
1165     pub glob_map: GlobMap,
1166
1167     used_imports: FxHashSet<(NodeId, Namespace)>,
1168     pub maybe_unused_trait_imports: NodeSet,
1169
1170     privacy_errors: Vec<PrivacyError<'a>>,
1171     ambiguity_errors: Vec<AmbiguityError<'a>>,
1172     gated_errors: FxHashSet<Span>,
1173     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1174
1175     arenas: &'a ResolverArenas<'a>,
1176     dummy_binding: &'a NameBinding<'a>,
1177     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1178
1179     crate_loader: &'a mut CrateLoader,
1180     macro_names: FxHashSet<Name>,
1181     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1182     lexical_macro_resolutions: Vec<(Name, &'a Cell<LegacyScope<'a>>)>,
1183     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1184     macro_defs: FxHashMap<Mark, DefId>,
1185     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1186     macro_exports: Vec<Export>,
1187     pub whitelisted_legacy_custom_derives: Vec<Name>,
1188     pub found_unresolved_macro: bool,
1189
1190     // Maps the `Mark` of an expansion to its containing module or block.
1191     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1192
1193     // Avoid duplicated errors for "name already defined".
1194     name_already_seen: FxHashMap<Name, Span>,
1195
1196     // If `#![feature(proc_macro)]` is set
1197     proc_macro_enabled: bool,
1198
1199     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1200     warned_proc_macros: FxHashSet<Name>,
1201
1202     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1203
1204     // This table maps struct IDs into struct constructor IDs,
1205     // it's not used during normal resolution, only for better error reporting.
1206     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1207 }
1208
1209 pub struct ResolverArenas<'a> {
1210     modules: arena::TypedArena<ModuleData<'a>>,
1211     local_modules: RefCell<Vec<Module<'a>>>,
1212     name_bindings: arena::TypedArena<NameBinding<'a>>,
1213     import_directives: arena::TypedArena<ImportDirective<'a>>,
1214     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1215     invocation_data: arena::TypedArena<InvocationData<'a>>,
1216     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1217 }
1218
1219 impl<'a> ResolverArenas<'a> {
1220     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1221         let module = self.modules.alloc(module);
1222         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1223             self.local_modules.borrow_mut().push(module);
1224         }
1225         module
1226     }
1227     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1228         self.local_modules.borrow()
1229     }
1230     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1231         self.name_bindings.alloc(name_binding)
1232     }
1233     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1234                               -> &'a ImportDirective {
1235         self.import_directives.alloc(import_directive)
1236     }
1237     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1238         self.name_resolutions.alloc(Default::default())
1239     }
1240     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1241                              -> &'a InvocationData<'a> {
1242         self.invocation_data.alloc(expansion_data)
1243     }
1244     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1245         self.legacy_bindings.alloc(binding)
1246     }
1247 }
1248
1249 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1250     fn parent(self, id: DefId) -> Option<DefId> {
1251         match id.krate {
1252             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1253             _ => self.session.cstore.def_key(id).parent,
1254         }.map(|index| DefId { index: index, ..id })
1255     }
1256 }
1257
1258 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1259     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1260         let namespace = if is_value { ValueNS } else { TypeNS };
1261         let hir::Path { ref segments, span, ref mut def } = *path;
1262         let path: Vec<_> = segments.iter().map(|seg| Ident::with_empty_ctxt(seg.name)).collect();
1263         match self.resolve_path(&path, Some(namespace), true, span) {
1264             PathResult::Module(module) => *def = module.def().unwrap(),
1265             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1266                 *def = path_res.base_def(),
1267             PathResult::NonModule(..) => match self.resolve_path(&path, None, true, span) {
1268                 PathResult::Failed(msg, _) => {
1269                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1270                 }
1271                 _ => {}
1272             },
1273             PathResult::Indeterminate => unreachable!(),
1274             PathResult::Failed(msg, _) => {
1275                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1276             }
1277         }
1278     }
1279
1280     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1281         self.def_map.get(&id).cloned()
1282     }
1283
1284     fn definitions(&mut self) -> &mut Definitions {
1285         &mut self.definitions
1286     }
1287 }
1288
1289 impl<'a> Resolver<'a> {
1290     pub fn new(session: &'a Session,
1291                krate: &Crate,
1292                crate_name: &str,
1293                make_glob_map: MakeGlobMap,
1294                crate_loader: &'a mut CrateLoader,
1295                arenas: &'a ResolverArenas<'a>)
1296                -> Resolver<'a> {
1297         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1298         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1299         let graph_root = arenas.alloc_module(ModuleData {
1300             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1301             ..ModuleData::new(None, root_module_kind, root_def_id, krate.span)
1302         });
1303         let mut module_map = FxHashMap();
1304         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1305
1306         let mut definitions = Definitions::new();
1307         DefCollector::new(&mut definitions)
1308             .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
1309
1310         let mut invocations = FxHashMap();
1311         invocations.insert(Mark::root(),
1312                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1313
1314         let features = session.features.borrow();
1315
1316         let mut macro_defs = FxHashMap();
1317         macro_defs.insert(Mark::root(), root_def_id);
1318
1319         Resolver {
1320             session: session,
1321
1322             definitions: definitions,
1323
1324             // The outermost module has def ID 0; this is not reflected in the
1325             // AST.
1326             graph_root: graph_root,
1327             prelude: None,
1328
1329             trait_item_map: FxHashMap(),
1330             field_names: FxHashMap(),
1331
1332             determined_imports: Vec::new(),
1333             indeterminate_imports: Vec::new(),
1334
1335             current_module: graph_root,
1336             ribs: PerNS {
1337                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1338                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1339                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1340             },
1341             label_ribs: Vec::new(),
1342
1343             current_trait_ref: None,
1344             current_self_type: None,
1345
1346             primitive_type_table: PrimitiveTypeTable::new(),
1347
1348             def_map: NodeMap(),
1349             freevars: NodeMap(),
1350             freevars_seen: NodeMap(),
1351             export_map: NodeMap(),
1352             trait_map: NodeMap(),
1353             module_map: module_map,
1354             block_map: NodeMap(),
1355             extern_crate_roots: FxHashMap(),
1356
1357             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1358             glob_map: NodeMap(),
1359
1360             used_imports: FxHashSet(),
1361             maybe_unused_trait_imports: NodeSet(),
1362
1363             privacy_errors: Vec::new(),
1364             ambiguity_errors: Vec::new(),
1365             gated_errors: FxHashSet(),
1366             disallowed_shadowing: Vec::new(),
1367
1368             arenas: arenas,
1369             dummy_binding: arenas.alloc_name_binding(NameBinding {
1370                 kind: NameBindingKind::Def(Def::Err),
1371                 expansion: Mark::root(),
1372                 span: DUMMY_SP,
1373                 vis: ty::Visibility::Public,
1374             }),
1375
1376             // `#![feature(proc_macro)]` implies `#[feature(extern_macros)]`
1377             use_extern_macros: features.use_extern_macros || features.proc_macro,
1378
1379             crate_loader: crate_loader,
1380             macro_names: FxHashSet(),
1381             global_macros: FxHashMap(),
1382             lexical_macro_resolutions: Vec::new(),
1383             macro_map: FxHashMap(),
1384             macro_exports: Vec::new(),
1385             invocations: invocations,
1386             macro_defs: macro_defs,
1387             local_macro_def_scopes: FxHashMap(),
1388             name_already_seen: FxHashMap(),
1389             whitelisted_legacy_custom_derives: Vec::new(),
1390             proc_macro_enabled: features.proc_macro,
1391             warned_proc_macros: FxHashSet(),
1392             potentially_unused_imports: Vec::new(),
1393             struct_constructors: DefIdMap(),
1394             found_unresolved_macro: false,
1395         }
1396     }
1397
1398     pub fn arenas() -> ResolverArenas<'a> {
1399         ResolverArenas {
1400             modules: arena::TypedArena::new(),
1401             local_modules: RefCell::new(Vec::new()),
1402             name_bindings: arena::TypedArena::new(),
1403             import_directives: arena::TypedArena::new(),
1404             name_resolutions: arena::TypedArena::new(),
1405             invocation_data: arena::TypedArena::new(),
1406             legacy_bindings: arena::TypedArena::new(),
1407         }
1408     }
1409
1410     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1411         PerNS {
1412             type_ns: f(self, TypeNS),
1413             value_ns: f(self, ValueNS),
1414             macro_ns: match self.use_extern_macros {
1415                 true => Some(f(self, MacroNS)),
1416                 false => None,
1417             },
1418         }
1419     }
1420
1421     /// Entry point to crate resolution.
1422     pub fn resolve_crate(&mut self, krate: &Crate) {
1423         ImportResolver { resolver: self }.finalize_imports();
1424         self.current_module = self.graph_root;
1425         self.finalize_current_module_macro_resolutions();
1426         visit::walk_crate(self, krate);
1427
1428         check_unused::check_crate(self, krate);
1429         self.report_errors();
1430         self.crate_loader.postprocess(krate);
1431     }
1432
1433     fn new_module(
1434         &self,
1435         parent: Module<'a>,
1436         kind: ModuleKind,
1437         normal_ancestor_id: DefId,
1438         span: Span,
1439     ) -> Module<'a> {
1440         self.arenas.alloc_module(ModuleData::new(Some(parent), kind, normal_ancestor_id, span))
1441     }
1442
1443     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1444                   -> bool /* true if an error was reported */ {
1445         match binding.kind {
1446             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1447                     if !used.get() => {
1448                 used.set(true);
1449                 directive.used.set(true);
1450                 if legacy_self_import {
1451                     self.warn_legacy_self_import(directive);
1452                     return false;
1453                 }
1454                 self.used_imports.insert((directive.id, ns));
1455                 self.add_to_glob_map(directive.id, ident);
1456                 self.record_use(ident, ns, binding, span)
1457             }
1458             NameBindingKind::Import { .. } => false,
1459             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1460                 self.ambiguity_errors.push(AmbiguityError {
1461                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1462                 });
1463                 if legacy {
1464                     self.record_use(ident, ns, b1, span);
1465                 }
1466                 !legacy
1467             }
1468             _ => false
1469         }
1470     }
1471
1472     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1473         if self.make_glob_map {
1474             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1475         }
1476     }
1477
1478     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1479     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1480     /// `ident` in the first scope that defines it (or None if no scopes define it).
1481     ///
1482     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1483     /// the items are defined in the block. For example,
1484     /// ```rust
1485     /// fn f() {
1486     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1487     ///    let g = || {};
1488     ///    fn g() {}
1489     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1490     /// }
1491     /// ```
1492     ///
1493     /// Invariant: This must only be called during main resolution, not during
1494     /// import resolution.
1495     fn resolve_ident_in_lexical_scope(&mut self,
1496                                       mut ident: Ident,
1497                                       ns: Namespace,
1498                                       record_used: bool,
1499                                       path_span: Span)
1500                                       -> Option<LexicalScopeBinding<'a>> {
1501         if ns == TypeNS {
1502             ident = ident.unhygienize();
1503         }
1504
1505         // Walk backwards up the ribs in scope.
1506         for i in (0 .. self.ribs[ns].len()).rev() {
1507             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1508                 // The ident resolves to a type parameter or local variable.
1509                 return Some(LexicalScopeBinding::Def(
1510                     self.adjust_local_def(ns, i, def, record_used, path_span)
1511                 ));
1512             }
1513
1514             if let ModuleRibKind(module) = self.ribs[ns][i].kind {
1515                 let item = self.resolve_ident_in_module(module, ident, ns, false,
1516                                                         record_used, path_span);
1517                 if let Ok(binding) = item {
1518                     // The ident resolves to an item.
1519                     return Some(LexicalScopeBinding::Item(binding));
1520                 }
1521
1522                 if let ModuleKind::Block(..) = module.kind { // We can see through blocks
1523                 } else if !module.no_implicit_prelude {
1524                     return self.prelude.and_then(|prelude| {
1525                         self.resolve_ident_in_module(prelude, ident, ns, false,
1526                                                      false, path_span).ok()
1527                     }).map(LexicalScopeBinding::Item)
1528                 } else {
1529                     return None;
1530                 }
1531             }
1532
1533             if let MacroDefinition(def) = self.ribs[ns][i].kind {
1534                 // If an invocation of this macro created `ident`, give up on `ident`
1535                 // and switch to `ident`'s source from the macro definition.
1536                 let ctxt_data = ident.ctxt.data();
1537                 if def == self.macro_defs[&ctxt_data.outer_mark] {
1538                     ident.ctxt = ctxt_data.prev_ctxt;
1539                 }
1540             }
1541         }
1542
1543         None
1544     }
1545
1546     fn resolve_crate_var(&mut self, crate_var_ctxt: SyntaxContext, span: Span) -> Module<'a> {
1547         let mut ctxt_data = crate_var_ctxt.data();
1548         while ctxt_data.prev_ctxt != SyntaxContext::empty() {
1549             ctxt_data = ctxt_data.prev_ctxt.data();
1550         }
1551         let module = self.macro_def_scope(ctxt_data.outer_mark, span);
1552         if module.is_local() { self.graph_root } else { module }
1553     }
1554
1555     // AST resolution
1556     //
1557     // We maintain a list of value ribs and type ribs.
1558     //
1559     // Simultaneously, we keep track of the current position in the module
1560     // graph in the `current_module` pointer. When we go to resolve a name in
1561     // the value or type namespaces, we first look through all the ribs and
1562     // then query the module graph. When we resolve a name in the module
1563     // namespace, we can skip all the ribs (since nested modules are not
1564     // allowed within blocks in Rust) and jump straight to the current module
1565     // graph node.
1566     //
1567     // Named implementations are handled separately. When we find a method
1568     // call, we consult the module node to find all of the implementations in
1569     // scope. This information is lazily cached in the module node. We then
1570     // generate a fake "implementation scope" containing all the
1571     // implementations thus found, for compatibility with old resolve pass.
1572
1573     fn with_scope<F>(&mut self, id: NodeId, f: F)
1574         where F: FnOnce(&mut Resolver)
1575     {
1576         let id = self.definitions.local_def_id(id);
1577         let module = self.module_map.get(&id).cloned(); // clones a reference
1578         if let Some(module) = module {
1579             // Move down in the graph.
1580             let orig_module = replace(&mut self.current_module, module);
1581             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1582             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1583
1584             self.finalize_current_module_macro_resolutions();
1585             f(self);
1586
1587             self.current_module = orig_module;
1588             self.ribs[ValueNS].pop();
1589             self.ribs[TypeNS].pop();
1590         } else {
1591             f(self);
1592         }
1593     }
1594
1595     /// Searches the current set of local scopes for labels.
1596     /// Stops after meeting a closure.
1597     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1598         for rib in self.label_ribs.iter().rev() {
1599             match rib.kind {
1600                 NormalRibKind => {
1601                     // Continue
1602                 }
1603                 MacroDefinition(def) => {
1604                     // If an invocation of this macro created `ident`, give up on `ident`
1605                     // and switch to `ident`'s source from the macro definition.
1606                     let ctxt_data = ident.ctxt.data();
1607                     if def == self.macro_defs[&ctxt_data.outer_mark] {
1608                         ident.ctxt = ctxt_data.prev_ctxt;
1609                     }
1610                 }
1611                 _ => {
1612                     // Do not resolve labels across function boundary
1613                     return None;
1614                 }
1615             }
1616             let result = rib.bindings.get(&ident).cloned();
1617             if result.is_some() {
1618                 return result;
1619             }
1620         }
1621         None
1622     }
1623
1624     fn resolve_item(&mut self, item: &Item) {
1625         let name = item.ident.name;
1626
1627         debug!("(resolving item) resolving {}", name);
1628
1629         self.check_proc_macro_attrs(&item.attrs);
1630
1631         match item.node {
1632             ItemKind::Enum(_, ref generics) |
1633             ItemKind::Ty(_, ref generics) |
1634             ItemKind::Struct(_, ref generics) |
1635             ItemKind::Union(_, ref generics) |
1636             ItemKind::Fn(.., ref generics, _) => {
1637                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1638                                              |this| visit::walk_item(this, item));
1639             }
1640
1641             ItemKind::DefaultImpl(_, ref trait_ref) => {
1642                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1643                     // Resolve type arguments in trait path
1644                     visit::walk_trait_ref(this, trait_ref);
1645                 });
1646             }
1647             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1648                 self.resolve_implementation(generics,
1649                                             opt_trait_ref,
1650                                             &self_type,
1651                                             item.id,
1652                                             impl_items),
1653
1654             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1655                 // Create a new rib for the trait-wide type parameters.
1656                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1657                     let local_def_id = this.definitions.local_def_id(item.id);
1658                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1659                         this.visit_generics(generics);
1660                         walk_list!(this, visit_ty_param_bound, bounds);
1661
1662                         for trait_item in trait_items {
1663                             this.check_proc_macro_attrs(&trait_item.attrs);
1664
1665                             match trait_item.node {
1666                                 TraitItemKind::Const(ref ty, ref default) => {
1667                                     this.visit_ty(ty);
1668
1669                                     // Only impose the restrictions of
1670                                     // ConstRibKind for an actual constant
1671                                     // expression in a provided default.
1672                                     if let Some(ref expr) = *default{
1673                                         this.with_constant_rib(|this| {
1674                                             this.visit_expr(expr);
1675                                         });
1676                                     }
1677                                 }
1678                                 TraitItemKind::Method(ref sig, _) => {
1679                                     let type_parameters =
1680                                         HasTypeParameters(&sig.generics,
1681                                                           MethodRibKind(!sig.decl.has_self()));
1682                                     this.with_type_parameter_rib(type_parameters, |this| {
1683                                         visit::walk_trait_item(this, trait_item)
1684                                     });
1685                                 }
1686                                 TraitItemKind::Type(..) => {
1687                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1688                                         visit::walk_trait_item(this, trait_item)
1689                                     });
1690                                 }
1691                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1692                             };
1693                         }
1694                     });
1695                 });
1696             }
1697
1698             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1699                 self.with_scope(item.id, |this| {
1700                     visit::walk_item(this, item);
1701                 });
1702             }
1703
1704             ItemKind::Static(ref ty, _, ref expr) |
1705             ItemKind::Const(ref ty, ref expr) => {
1706                 self.with_item_rib(|this| {
1707                     this.visit_ty(ty);
1708                     this.with_constant_rib(|this| {
1709                         this.visit_expr(expr);
1710                     });
1711                 });
1712             }
1713
1714             ItemKind::Use(ref view_path) => {
1715                 match view_path.node {
1716                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1717                         // Resolve prefix of an import with empty braces (issue #28388).
1718                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1719                     }
1720                     _ => {}
1721                 }
1722             }
1723
1724             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(_)=> {
1725                 // do nothing, these are just around to be encoded
1726             }
1727
1728             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1729         }
1730     }
1731
1732     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1733         where F: FnOnce(&mut Resolver)
1734     {
1735         match type_parameters {
1736             HasTypeParameters(generics, rib_kind) => {
1737                 let mut function_type_rib = Rib::new(rib_kind);
1738                 let mut seen_bindings = FxHashMap();
1739                 for type_parameter in &generics.ty_params {
1740                     let name = type_parameter.ident.name;
1741                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1742
1743                     if seen_bindings.contains_key(&name) {
1744                         let span = seen_bindings.get(&name).unwrap();
1745                         resolve_error(self,
1746                                       type_parameter.span,
1747                                       ResolutionError::NameAlreadyUsedInTypeParameterList(name,
1748                                                                                           span));
1749                     }
1750                     seen_bindings.entry(name).or_insert(type_parameter.span);
1751
1752                     // plain insert (no renaming)
1753                     let def_id = self.definitions.local_def_id(type_parameter.id);
1754                     let def = Def::TyParam(def_id);
1755                     function_type_rib.bindings.insert(Ident::with_empty_ctxt(name), def);
1756                     self.record_def(type_parameter.id, PathResolution::new(def));
1757                 }
1758                 self.ribs[TypeNS].push(function_type_rib);
1759             }
1760
1761             NoTypeParameters => {
1762                 // Nothing to do.
1763             }
1764         }
1765
1766         f(self);
1767
1768         if let HasTypeParameters(..) = type_parameters {
1769             self.ribs[TypeNS].pop();
1770         }
1771     }
1772
1773     fn with_label_rib<F>(&mut self, f: F)
1774         where F: FnOnce(&mut Resolver)
1775     {
1776         self.label_ribs.push(Rib::new(NormalRibKind));
1777         f(self);
1778         self.label_ribs.pop();
1779     }
1780
1781     fn with_item_rib<F>(&mut self, f: F)
1782         where F: FnOnce(&mut Resolver)
1783     {
1784         self.ribs[ValueNS].push(Rib::new(ItemRibKind));
1785         self.ribs[TypeNS].push(Rib::new(ItemRibKind));
1786         f(self);
1787         self.ribs[TypeNS].pop();
1788         self.ribs[ValueNS].pop();
1789     }
1790
1791     fn with_constant_rib<F>(&mut self, f: F)
1792         where F: FnOnce(&mut Resolver)
1793     {
1794         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1795         f(self);
1796         self.ribs[ValueNS].pop();
1797     }
1798
1799     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1800         where F: FnOnce(&mut Resolver) -> T
1801     {
1802         // Handle nested impls (inside fn bodies)
1803         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1804         let result = f(self);
1805         self.current_self_type = previous_value;
1806         result
1807     }
1808
1809     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1810         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1811     {
1812         let mut new_val = None;
1813         let mut new_id = None;
1814         if let Some(trait_ref) = opt_trait_ref {
1815             let def = self.smart_resolve_path(trait_ref.ref_id, None,
1816                                               &trait_ref.path, PathSource::Trait).base_def();
1817             if def != Def::Err {
1818                 new_val = Some((def.def_id(), trait_ref.clone()));
1819                 new_id = Some(def.def_id());
1820             }
1821         }
1822         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1823         let result = f(self, new_id);
1824         self.current_trait_ref = original_trait_ref;
1825         result
1826     }
1827
1828     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1829         where F: FnOnce(&mut Resolver)
1830     {
1831         let mut self_type_rib = Rib::new(NormalRibKind);
1832
1833         // plain insert (no renaming, types are not currently hygienic....)
1834         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1835         self.ribs[TypeNS].push(self_type_rib);
1836         f(self);
1837         self.ribs[TypeNS].pop();
1838     }
1839
1840     fn resolve_implementation(&mut self,
1841                               generics: &Generics,
1842                               opt_trait_reference: &Option<TraitRef>,
1843                               self_type: &Ty,
1844                               item_id: NodeId,
1845                               impl_items: &[ImplItem]) {
1846         // If applicable, create a rib for the type parameters.
1847         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1848             // Dummy self type for better errors if `Self` is used in the trait path.
1849             this.with_self_rib(Def::SelfTy(None, None), |this| {
1850                 // Resolve the trait reference, if necessary.
1851                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1852                     let item_def_id = this.definitions.local_def_id(item_id);
1853                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1854                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1855                             // Resolve type arguments in trait path
1856                             visit::walk_trait_ref(this, trait_ref);
1857                         }
1858                         // Resolve the self type.
1859                         this.visit_ty(self_type);
1860                         // Resolve the type parameters.
1861                         this.visit_generics(generics);
1862                         this.with_current_self_type(self_type, |this| {
1863                             for impl_item in impl_items {
1864                                 this.check_proc_macro_attrs(&impl_item.attrs);
1865                                 this.resolve_visibility(&impl_item.vis);
1866                                 match impl_item.node {
1867                                     ImplItemKind::Const(..) => {
1868                                         // If this is a trait impl, ensure the const
1869                                         // exists in trait
1870                                         this.check_trait_item(impl_item.ident.name,
1871                                                             ValueNS,
1872                                                             impl_item.span,
1873                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1874                                         visit::walk_impl_item(this, impl_item);
1875                                     }
1876                                     ImplItemKind::Method(ref sig, _) => {
1877                                         // If this is a trait impl, ensure the method
1878                                         // exists in trait
1879                                         this.check_trait_item(impl_item.ident.name,
1880                                                             ValueNS,
1881                                                             impl_item.span,
1882                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
1883
1884                                         // We also need a new scope for the method-
1885                                         // specific type parameters.
1886                                         let type_parameters =
1887                                             HasTypeParameters(&sig.generics,
1888                                                             MethodRibKind(!sig.decl.has_self()));
1889                                         this.with_type_parameter_rib(type_parameters, |this| {
1890                                             visit::walk_impl_item(this, impl_item);
1891                                         });
1892                                     }
1893                                     ImplItemKind::Type(ref ty) => {
1894                                         // If this is a trait impl, ensure the type
1895                                         // exists in trait
1896                                         this.check_trait_item(impl_item.ident.name,
1897                                                             TypeNS,
1898                                                             impl_item.span,
1899                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
1900
1901                                         this.visit_ty(ty);
1902                                     }
1903                                     ImplItemKind::Macro(_) =>
1904                                         panic!("unexpanded macro in resolve!"),
1905                                 }
1906                             }
1907                         });
1908                     });
1909                 });
1910             });
1911         });
1912     }
1913
1914     fn check_trait_item<F>(&self, name: Name, ns: Namespace, span: Span, err: F)
1915         where F: FnOnce(Name, &str) -> ResolutionError
1916     {
1917         // If there is a TraitRef in scope for an impl, then the method must be in the
1918         // trait.
1919         if let Some((did, ref trait_ref)) = self.current_trait_ref {
1920             if !self.trait_item_map.contains_key(&(did, name, ns)) {
1921                 let path_str = path_names_to_string(&trait_ref.path);
1922                 resolve_error(self, span, err(name, &path_str));
1923             }
1924         }
1925     }
1926
1927     fn resolve_local(&mut self, local: &Local) {
1928         // Resolve the type.
1929         walk_list!(self, visit_ty, &local.ty);
1930
1931         // Resolve the initializer.
1932         walk_list!(self, visit_expr, &local.init);
1933
1934         // Resolve the pattern.
1935         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
1936     }
1937
1938     // build a map from pattern identifiers to binding-info's.
1939     // this is done hygienically. This could arise for a macro
1940     // that expands into an or-pattern where one 'x' was from the
1941     // user and one 'x' came from the macro.
1942     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
1943         let mut binding_map = FxHashMap();
1944
1945         pat.walk(&mut |pat| {
1946             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
1947                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
1948                     Some(Def::Local(..)) => true,
1949                     _ => false,
1950                 } {
1951                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
1952                     binding_map.insert(ident.node, binding_info);
1953                 }
1954             }
1955             true
1956         });
1957
1958         binding_map
1959     }
1960
1961     // check that all of the arms in an or-pattern have exactly the
1962     // same set of bindings, with the same binding modes for each.
1963     fn check_consistent_bindings(&mut self, arm: &Arm) {
1964         if arm.pats.is_empty() {
1965             return;
1966         }
1967
1968         let mut missing_vars = FxHashMap();
1969         let mut inconsistent_vars = FxHashMap();
1970         for (i, p) in arm.pats.iter().enumerate() {
1971             let map_i = self.binding_mode_map(&p);
1972
1973             for (j, q) in arm.pats.iter().enumerate() {
1974                 if i == j {
1975                     continue;
1976                 }
1977
1978                 let map_j = self.binding_mode_map(&q);
1979                 for (&key, &binding_i) in &map_i {
1980                     if map_j.len() == 0 {                   // Account for missing bindings when
1981                         let binding_error = missing_vars    // map_j has none.
1982                             .entry(key.name)
1983                             .or_insert(BindingError {
1984                                 name: key.name,
1985                                 origin: BTreeSet::new(),
1986                                 target: BTreeSet::new(),
1987                             });
1988                         binding_error.origin.insert(binding_i.span);
1989                         binding_error.target.insert(q.span);
1990                     }
1991                     for (&key_j, &binding_j) in &map_j {
1992                         match map_i.get(&key_j) {
1993                             None => {  // missing binding
1994                                 let binding_error = missing_vars
1995                                     .entry(key_j.name)
1996                                     .or_insert(BindingError {
1997                                         name: key_j.name,
1998                                         origin: BTreeSet::new(),
1999                                         target: BTreeSet::new(),
2000                                     });
2001                                 binding_error.origin.insert(binding_j.span);
2002                                 binding_error.target.insert(p.span);
2003                             }
2004                             Some(binding_i) => {  // check consistent binding
2005                                 if binding_i.binding_mode != binding_j.binding_mode {
2006                                     inconsistent_vars
2007                                         .entry(key.name)
2008                                         .or_insert((binding_j.span, binding_i.span));
2009                                 }
2010                             }
2011                         }
2012                     }
2013                 }
2014             }
2015         }
2016         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
2017         missing_vars.sort();
2018         for (_, v) in missing_vars {
2019             resolve_error(self,
2020                           *v.origin.iter().next().unwrap(),
2021                           ResolutionError::VariableNotBoundInPattern(v));
2022         }
2023         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2024         inconsistent_vars.sort();
2025         for (name, v) in inconsistent_vars {
2026             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2027         }
2028     }
2029
2030     fn resolve_arm(&mut self, arm: &Arm) {
2031         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2032
2033         let mut bindings_list = FxHashMap();
2034         for pattern in &arm.pats {
2035             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2036         }
2037
2038         // This has to happen *after* we determine which
2039         // pat_idents are variants
2040         self.check_consistent_bindings(arm);
2041
2042         walk_list!(self, visit_expr, &arm.guard);
2043         self.visit_expr(&arm.body);
2044
2045         self.ribs[ValueNS].pop();
2046     }
2047
2048     fn resolve_block(&mut self, block: &Block) {
2049         debug!("(resolving block) entering block");
2050         // Move down in the graph, if there's an anonymous module rooted here.
2051         let orig_module = self.current_module;
2052         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2053
2054         let mut num_macro_definition_ribs = 0;
2055         if let Some(anonymous_module) = anonymous_module {
2056             debug!("(resolving block) found anonymous module, moving down");
2057             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2058             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2059             self.current_module = anonymous_module;
2060             self.finalize_current_module_macro_resolutions();
2061         } else {
2062             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2063         }
2064
2065         // Descend into the block.
2066         for stmt in &block.stmts {
2067             if let ast::StmtKind::Item(ref item) = stmt.node {
2068                 if let ast::ItemKind::MacroDef(..) = item.node {
2069                     num_macro_definition_ribs += 1;
2070                     let def = self.definitions.local_def_id(item.id);
2071                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2072                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2073                 }
2074             }
2075
2076             self.visit_stmt(stmt);
2077         }
2078
2079         // Move back up.
2080         self.current_module = orig_module;
2081         for _ in 0 .. num_macro_definition_ribs {
2082             self.ribs[ValueNS].pop();
2083             self.label_ribs.pop();
2084         }
2085         self.ribs[ValueNS].pop();
2086         if let Some(_) = anonymous_module {
2087             self.ribs[TypeNS].pop();
2088         }
2089         debug!("(resolving block) leaving block");
2090     }
2091
2092     fn fresh_binding(&mut self,
2093                      ident: &SpannedIdent,
2094                      pat_id: NodeId,
2095                      outer_pat_id: NodeId,
2096                      pat_src: PatternSource,
2097                      bindings: &mut FxHashMap<Ident, NodeId>)
2098                      -> PathResolution {
2099         // Add the binding to the local ribs, if it
2100         // doesn't already exist in the bindings map. (We
2101         // must not add it if it's in the bindings map
2102         // because that breaks the assumptions later
2103         // passes make about or-patterns.)
2104         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2105         match bindings.get(&ident.node).cloned() {
2106             Some(id) if id == outer_pat_id => {
2107                 // `Variant(a, a)`, error
2108                 resolve_error(
2109                     self,
2110                     ident.span,
2111                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2112                         &ident.node.name.as_str())
2113                 );
2114             }
2115             Some(..) if pat_src == PatternSource::FnParam => {
2116                 // `fn f(a: u8, a: u8)`, error
2117                 resolve_error(
2118                     self,
2119                     ident.span,
2120                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2121                         &ident.node.name.as_str())
2122                 );
2123             }
2124             Some(..) if pat_src == PatternSource::Match => {
2125                 // `Variant1(a) | Variant2(a)`, ok
2126                 // Reuse definition from the first `a`.
2127                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2128             }
2129             Some(..) => {
2130                 span_bug!(ident.span, "two bindings with the same name from \
2131                                        unexpected pattern source {:?}", pat_src);
2132             }
2133             None => {
2134                 // A completely fresh binding, add to the lists if it's valid.
2135                 if ident.node.name != keywords::Invalid.name() {
2136                     bindings.insert(ident.node, outer_pat_id);
2137                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2138                 }
2139             }
2140         }
2141
2142         PathResolution::new(def)
2143     }
2144
2145     fn resolve_pattern(&mut self,
2146                        pat: &Pat,
2147                        pat_src: PatternSource,
2148                        // Maps idents to the node ID for the
2149                        // outermost pattern that binds them.
2150                        bindings: &mut FxHashMap<Ident, NodeId>) {
2151         // Visit all direct subpatterns of this pattern.
2152         let outer_pat_id = pat.id;
2153         pat.walk(&mut |pat| {
2154             match pat.node {
2155                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2156                     // First try to resolve the identifier as some existing
2157                     // entity, then fall back to a fresh binding.
2158                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS,
2159                                                                       false, pat.span)
2160                                       .and_then(LexicalScopeBinding::item);
2161                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2162                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2163                                              bmode != BindingMode::ByValue(Mutability::Immutable);
2164                         match def {
2165                             Def::StructCtor(_, CtorKind::Const) |
2166                             Def::VariantCtor(_, CtorKind::Const) |
2167                             Def::Const(..) if !always_binding => {
2168                                 // A unit struct/variant or constant pattern.
2169                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2170                                 Some(PathResolution::new(def))
2171                             }
2172                             Def::StructCtor(..) | Def::VariantCtor(..) |
2173                             Def::Const(..) | Def::Static(..) => {
2174                                 // A fresh binding that shadows something unacceptable.
2175                                 resolve_error(
2176                                     self,
2177                                     ident.span,
2178                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2179                                         pat_src.descr(), ident.node.name, binding.unwrap())
2180                                 );
2181                                 None
2182                             }
2183                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2184                                 // These entities are explicitly allowed
2185                                 // to be shadowed by fresh bindings.
2186                                 None
2187                             }
2188                             def => {
2189                                 span_bug!(ident.span, "unexpected definition for an \
2190                                                        identifier in pattern: {:?}", def);
2191                             }
2192                         }
2193                     }).unwrap_or_else(|| {
2194                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2195                     });
2196
2197                     self.record_def(pat.id, resolution);
2198                 }
2199
2200                 PatKind::TupleStruct(ref path, ..) => {
2201                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2202                 }
2203
2204                 PatKind::Path(ref qself, ref path) => {
2205                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2206                 }
2207
2208                 PatKind::Struct(ref path, ..) => {
2209                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2210                 }
2211
2212                 _ => {}
2213             }
2214             true
2215         });
2216
2217         visit::walk_pat(self, pat);
2218     }
2219
2220     // High-level and context dependent path resolution routine.
2221     // Resolves the path and records the resolution into definition map.
2222     // If resolution fails tries several techniques to find likely
2223     // resolution candidates, suggest imports or other help, and report
2224     // errors in user friendly way.
2225     fn smart_resolve_path(&mut self,
2226                           id: NodeId,
2227                           qself: Option<&QSelf>,
2228                           path: &Path,
2229                           source: PathSource)
2230                           -> PathResolution {
2231         let segments = &path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>();
2232         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2233         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2234     }
2235
2236     fn smart_resolve_path_fragment(&mut self,
2237                                    id: NodeId,
2238                                    qself: Option<&QSelf>,
2239                                    path: &[Ident],
2240                                    span: Span,
2241                                    ident_span: Span,
2242                                    source: PathSource)
2243                                    -> PathResolution {
2244         let ns = source.namespace();
2245         let is_expected = &|def| source.is_expected(def);
2246         let is_enum_variant = &|def| if let Def::Variant(..) = def { true } else { false };
2247
2248         // Base error is amended with one short label and possibly some longer helps/notes.
2249         let report_errors = |this: &mut Self, def: Option<Def>| {
2250             // Make the base error.
2251             let expected = source.descr_expected();
2252             let path_str = names_to_string(path);
2253             let code = source.error_code(def.is_some());
2254             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2255                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2256                  format!("not a {}", expected), span)
2257             } else {
2258                 let item_str = path[path.len() - 1];
2259                 let (mod_prefix, mod_str) = if path.len() == 1 {
2260                     (format!(""), format!("this scope"))
2261                 } else if path.len() == 2 && path[0].name == keywords::CrateRoot.name() {
2262                     (format!(""), format!("the crate root"))
2263                 } else {
2264                     let mod_path = &path[..path.len() - 1];
2265                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), false, span) {
2266                         PathResult::Module(module) => module.def(),
2267                         _ => None,
2268                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2269                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2270                 };
2271                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2272                  format!("not found in {}", mod_str), ident_span)
2273             };
2274             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2275
2276             // Emit special messages for unresolved `Self` and `self`.
2277             if is_self_type(path, ns) {
2278                 __diagnostic_used!(E0411);
2279                 err.code("E0411".into());
2280                 err.span_label(span, "`Self` is only available in traits and impls");
2281                 return err;
2282             }
2283             if is_self_value(path, ns) {
2284                 __diagnostic_used!(E0424);
2285                 err.code("E0424".into());
2286                 err.span_label(span, format!("`self` value is only available in \
2287                                                methods with `self` parameter"));
2288                 return err;
2289             }
2290
2291             // Try to lookup the name in more relaxed fashion for better error reporting.
2292             let name = path.last().unwrap().name;
2293             let candidates = this.lookup_import_candidates(name, ns, is_expected);
2294             if !candidates.is_empty() {
2295                 let mut module_span = this.current_module.span;
2296                 module_span.hi = module_span.lo;
2297                 // Report import candidates as help and proceed searching for labels.
2298                 show_candidates(&mut err, module_span, &candidates, def.is_some());
2299             } else if is_expected(Def::Enum(DefId::local(CRATE_DEF_INDEX))) {
2300                 let enum_candidates = this.lookup_import_candidates(name, ns, is_enum_variant);
2301                 let mut enum_candidates = enum_candidates.iter()
2302                     .map(|suggestion| import_candidate_to_paths(&suggestion)).collect::<Vec<_>>();
2303                 enum_candidates.sort();
2304                 for (sp, variant_path, enum_path) in enum_candidates {
2305                     let msg = format!("there is an enum variant `{}`, did you mean to use `{}`?",
2306                                       variant_path,
2307                                       enum_path);
2308                     if sp == DUMMY_SP {
2309                         err.help(&msg);
2310                     } else {
2311                         err.span_help(sp, &msg);
2312                     }
2313                 }
2314             }
2315             if path.len() == 1 && this.self_type_is_available(span) {
2316                 if let Some(candidate) = this.lookup_assoc_candidate(name, ns, is_expected) {
2317                     let self_is_available = this.self_value_is_available(path[0].ctxt, span);
2318                     match candidate {
2319                         AssocSuggestion::Field => {
2320                             err.span_label(span, format!("did you mean `self.{}`?", path_str));
2321                             if !self_is_available {
2322                                 err.span_label(span, format!("`self` value is only available in \
2323                                                                methods with `self` parameter"));
2324                             }
2325                         }
2326                         AssocSuggestion::MethodWithSelf if self_is_available => {
2327                             err.span_label(span, format!("did you mean `self.{}(...)`?",
2328                                                            path_str));
2329                         }
2330                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2331                             err.span_label(span, format!("did you mean `Self::{}`?", path_str));
2332                         }
2333                     }
2334                     return err;
2335                 }
2336             }
2337
2338             let mut levenshtein_worked = false;
2339
2340             // Try Levenshtein.
2341             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected, span) {
2342                 err.span_label(ident_span, format!("did you mean `{}`?", candidate));
2343                 levenshtein_worked = true;
2344             }
2345
2346             // Try context dependent help if relaxed lookup didn't work.
2347             if let Some(def) = def {
2348                 match (def, source) {
2349                     (Def::Macro(..), _) => {
2350                         err.span_label(span, format!("did you mean `{}!(...)`?", path_str));
2351                         return err;
2352                     }
2353                     (Def::TyAlias(..), PathSource::Trait) => {
2354                         err.span_label(span, "type aliases cannot be used for traits");
2355                         return err;
2356                     }
2357                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2358                         ExprKind::Field(_, ident) => {
2359                             err.span_label(parent.span, format!("did you mean `{}::{}`?",
2360                                                                  path_str, ident.node));
2361                             return err;
2362                         }
2363                         ExprKind::MethodCall(ident, ..) => {
2364                             err.span_label(parent.span, format!("did you mean `{}::{}(...)`?",
2365                                                                  path_str, ident.node));
2366                             return err;
2367                         }
2368                         _ => {}
2369                     },
2370                     _ if ns == ValueNS && is_struct_like(def) => {
2371                         if let Def::Struct(def_id) = def {
2372                             if let Some((ctor_def, ctor_vis))
2373                                     = this.struct_constructors.get(&def_id).cloned() {
2374                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2375                                     err.span_label(span, format!("constructor is not visible \
2376                                                                    here due to private fields"));
2377                                 }
2378                             }
2379                         }
2380                         err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?",
2381                                                        path_str));
2382                         return err;
2383                     }
2384                     _ => {}
2385                 }
2386             }
2387
2388             // Fallback label.
2389             if !levenshtein_worked {
2390                 err.span_label(base_span, fallback_label);
2391             }
2392             err
2393         };
2394         let report_errors = |this: &mut Self, def: Option<Def>| {
2395             report_errors(this, def).emit();
2396             err_path_resolution()
2397         };
2398
2399         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2400                                                            source.defer_to_typeck(),
2401                                                            source.global_by_default()) {
2402             Some(resolution) if resolution.unresolved_segments() == 0 => {
2403                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2404                     resolution
2405                 } else {
2406                     // Add a temporary hack to smooth the transition to new struct ctor
2407                     // visibility rules. See #38932 for more details.
2408                     let mut res = None;
2409                     if let Def::Struct(def_id) = resolution.base_def() {
2410                         if let Some((ctor_def, ctor_vis))
2411                                 = self.struct_constructors.get(&def_id).cloned() {
2412                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2413                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2414                                 self.session.add_lint(lint, id, span,
2415                                     "private struct constructors are not usable through \
2416                                      reexports in outer modules".to_string());
2417                                 res = Some(PathResolution::new(ctor_def));
2418                             }
2419                         }
2420                     }
2421
2422                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2423                 }
2424             }
2425             Some(resolution) if source.defer_to_typeck() => {
2426                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2427                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2428                 // it needs to be added to the trait map.
2429                 if ns == ValueNS {
2430                     let item_name = path.last().unwrap().name;
2431                     let traits = self.get_traits_containing_item(item_name, ns);
2432                     self.trait_map.insert(id, traits);
2433                 }
2434                 resolution
2435             }
2436             _ => report_errors(self, None)
2437         };
2438
2439         if let PathSource::TraitItem(..) = source {} else {
2440             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2441             self.record_def(id, resolution);
2442         }
2443         resolution
2444     }
2445
2446     fn self_type_is_available(&mut self, span: Span) -> bool {
2447         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(),
2448                                                           TypeNS, false, span);
2449         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2450     }
2451
2452     fn self_value_is_available(&mut self, ctxt: SyntaxContext, span: Span) -> bool {
2453         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2454         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, false, span);
2455         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2456     }
2457
2458     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2459     fn resolve_qpath_anywhere(&mut self,
2460                               id: NodeId,
2461                               qself: Option<&QSelf>,
2462                               path: &[Ident],
2463                               primary_ns: Namespace,
2464                               span: Span,
2465                               defer_to_typeck: bool,
2466                               global_by_default: bool)
2467                               -> Option<PathResolution> {
2468         let mut fin_res = None;
2469         // FIXME: can't resolve paths in macro namespace yet, macros are
2470         // processed by the little special hack below.
2471         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2472             if i == 0 || ns != primary_ns {
2473                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2474                     // If defer_to_typeck, then resolution > no resolution,
2475                     // otherwise full resolution > partial resolution > no resolution.
2476                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2477                         return Some(res),
2478                     res => if fin_res.is_none() { fin_res = res },
2479                 };
2480             }
2481         }
2482         let is_global = self.global_macros.get(&path[0].name).cloned()
2483             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2484         if primary_ns != MacroNS && (is_global || self.macro_names.contains(&path[0].name)) {
2485             // Return some dummy definition, it's enough for error reporting.
2486             return Some(
2487                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2488             );
2489         }
2490         fin_res
2491     }
2492
2493     /// Handles paths that may refer to associated items.
2494     fn resolve_qpath(&mut self,
2495                      id: NodeId,
2496                      qself: Option<&QSelf>,
2497                      path: &[Ident],
2498                      ns: Namespace,
2499                      span: Span,
2500                      global_by_default: bool)
2501                      -> Option<PathResolution> {
2502         if let Some(qself) = qself {
2503             if qself.position == 0 {
2504                 // FIXME: Create some fake resolution that can't possibly be a type.
2505                 return Some(PathResolution::with_unresolved_segments(
2506                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2507                 ));
2508             }
2509             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2510             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2511             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2512                                                        span, span, PathSource::TraitItem(ns));
2513             return Some(PathResolution::with_unresolved_segments(
2514                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2515             ));
2516         }
2517
2518         let result = match self.resolve_path(&path, Some(ns), true, span) {
2519             PathResult::NonModule(path_res) => path_res,
2520             PathResult::Module(module) if !module.is_normal() => {
2521                 PathResolution::new(module.def().unwrap())
2522             }
2523             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2524             // don't report an error right away, but try to fallback to a primitive type.
2525             // So, we are still able to successfully resolve something like
2526             //
2527             // use std::u8; // bring module u8 in scope
2528             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2529             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2530             //                     // not to non-existent std::u8::max_value
2531             // }
2532             //
2533             // Such behavior is required for backward compatibility.
2534             // The same fallback is used when `a` resolves to nothing.
2535             PathResult::Module(..) | PathResult::Failed(..)
2536                     if (ns == TypeNS || path.len() > 1) &&
2537                        self.primitive_type_table.primitive_types.contains_key(&path[0].name) => {
2538                 let prim = self.primitive_type_table.primitive_types[&path[0].name];
2539                 match prim {
2540                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2541                         if !self.session.features.borrow().i128_type {
2542                             emit_feature_err(&self.session.parse_sess,
2543                                                 "i128_type", span, GateIssue::Language,
2544                                                 "128-bit type is unstable");
2545
2546                         }
2547                     }
2548                     _ => {}
2549                 }
2550                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2551             }
2552             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2553             PathResult::Failed(msg, false) => {
2554                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2555                 err_path_resolution()
2556             }
2557             PathResult::Failed(..) => return None,
2558             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2559         };
2560
2561         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2562            path[0].name != keywords::CrateRoot.name() && path[0].name != "$crate" {
2563             let unqualified_result = {
2564                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), false, span) {
2565                     PathResult::NonModule(path_res) => path_res.base_def(),
2566                     PathResult::Module(module) => module.def().unwrap(),
2567                     _ => return Some(result),
2568                 }
2569             };
2570             if result.base_def() == unqualified_result {
2571                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2572                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2573             }
2574         }
2575
2576         Some(result)
2577     }
2578
2579     fn resolve_path(&mut self,
2580                     path: &[Ident],
2581                     opt_ns: Option<Namespace>, // `None` indicates a module path
2582                     record_used: bool,
2583                     path_span: Span)
2584                     -> PathResult<'a> {
2585         let mut module = None;
2586         let mut allow_super = true;
2587
2588         for (i, &ident) in path.iter().enumerate() {
2589             let is_last = i == path.len() - 1;
2590             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2591
2592             if i == 0 && ns == TypeNS && ident.name == keywords::SelfValue.name() {
2593                 module = Some(self.module_map[&self.current_module.normal_ancestor_id]);
2594                 continue
2595             } else if allow_super && ns == TypeNS && ident.name == keywords::Super.name() {
2596                 let current_module = if i == 0 { self.current_module } else { module.unwrap() };
2597                 let self_module = self.module_map[&current_module.normal_ancestor_id];
2598                 if let Some(parent) = self_module.parent {
2599                     module = Some(self.module_map[&parent.normal_ancestor_id]);
2600                     continue
2601                 } else {
2602                     let msg = "There are too many initial `super`s.".to_string();
2603                     return PathResult::Failed(msg, false);
2604                 }
2605             }
2606             allow_super = false;
2607
2608             if i == 0 && ns == TypeNS && ident.name == keywords::CrateRoot.name() {
2609                 module = Some(self.graph_root);
2610                 continue
2611             } else if i == 0 && ns == TypeNS && ident.name == "$crate" {
2612                 module = Some(self.resolve_crate_var(ident.ctxt, path_span));
2613                 continue
2614             }
2615
2616             let binding = if let Some(module) = module {
2617                 self.resolve_ident_in_module(module, ident, ns, false, record_used, path_span)
2618             } else if opt_ns == Some(MacroNS) {
2619                 self.resolve_lexical_macro_path_segment(ident, ns, record_used, path_span)
2620                     .map(MacroBinding::binding)
2621             } else {
2622                 match self.resolve_ident_in_lexical_scope(ident, ns, record_used, path_span) {
2623                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2624                     Some(LexicalScopeBinding::Def(def))
2625                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2626                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2627                             def, path.len() - 1
2628                         ));
2629                     }
2630                     _ => Err(if record_used { Determined } else { Undetermined }),
2631                 }
2632             };
2633
2634             match binding {
2635                 Ok(binding) => {
2636                     let def = binding.def();
2637                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2638                     if let Some(next_module) = binding.module() {
2639                         module = Some(next_module);
2640                     } else if def == Def::Err {
2641                         return PathResult::NonModule(err_path_resolution());
2642                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2643                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2644                             def, path.len() - i - 1
2645                         ));
2646                     } else {
2647                         return PathResult::Failed(format!("Not a module `{}`", ident), is_last);
2648                     }
2649                 }
2650                 Err(Undetermined) => return PathResult::Indeterminate,
2651                 Err(Determined) => {
2652                     if let Some(module) = module {
2653                         if opt_ns.is_some() && !module.is_normal() {
2654                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2655                                 module.def().unwrap(), path.len() - i
2656                             ));
2657                         }
2658                     }
2659                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2660                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2661                         let mut candidates =
2662                             self.lookup_import_candidates(ident.name, TypeNS, is_mod);
2663                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2664                         if let Some(candidate) = candidates.get(0) {
2665                             format!("Did you mean `{}`?", candidate.path)
2666                         } else {
2667                             format!("Maybe a missing `extern crate {};`?", ident)
2668                         }
2669                     } else if i == 0 {
2670                         format!("Use of undeclared type or module `{}`", ident)
2671                     } else {
2672                         format!("Could not find `{}` in `{}`", ident, path[i - 1])
2673                     };
2674                     return PathResult::Failed(msg, is_last);
2675                 }
2676             }
2677         }
2678
2679         PathResult::Module(module.unwrap_or(self.graph_root))
2680     }
2681
2682     // Resolve a local definition, potentially adjusting for closures.
2683     fn adjust_local_def(&mut self,
2684                         ns: Namespace,
2685                         rib_index: usize,
2686                         mut def: Def,
2687                         record_used: bool,
2688                         span: Span) -> Def {
2689         let ribs = &self.ribs[ns][rib_index + 1..];
2690
2691         // An invalid forward use of a type parameter from a previous default.
2692         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2693             if record_used {
2694                 resolve_error(self, span,
2695                         ResolutionError::ForwardDeclaredTyParam);
2696             }
2697             assert_eq!(def, Def::Err);
2698             return Def::Err;
2699         }
2700
2701         match def {
2702             Def::Upvar(..) => {
2703                 span_bug!(span, "unexpected {:?} in bindings", def)
2704             }
2705             Def::Local(def_id) => {
2706                 for rib in ribs {
2707                     match rib.kind {
2708                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2709                         ForwardTyParamBanRibKind => {
2710                             // Nothing to do. Continue.
2711                         }
2712                         ClosureRibKind(function_id) => {
2713                             let prev_def = def;
2714                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2715
2716                             let seen = self.freevars_seen
2717                                            .entry(function_id)
2718                                            .or_insert_with(|| NodeMap());
2719                             if let Some(&index) = seen.get(&node_id) {
2720                                 def = Def::Upvar(def_id, index, function_id);
2721                                 continue;
2722                             }
2723                             let vec = self.freevars
2724                                           .entry(function_id)
2725                                           .or_insert_with(|| vec![]);
2726                             let depth = vec.len();
2727                             def = Def::Upvar(def_id, depth, function_id);
2728
2729                             if record_used {
2730                                 vec.push(Freevar {
2731                                     def: prev_def,
2732                                     span: span,
2733                                 });
2734                                 seen.insert(node_id, depth);
2735                             }
2736                         }
2737                         ItemRibKind | MethodRibKind(_) => {
2738                             // This was an attempt to access an upvar inside a
2739                             // named function item. This is not allowed, so we
2740                             // report an error.
2741                             if record_used {
2742                                 resolve_error(self, span,
2743                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2744                             }
2745                             return Def::Err;
2746                         }
2747                         ConstantItemRibKind => {
2748                             // Still doesn't deal with upvars
2749                             if record_used {
2750                                 resolve_error(self, span,
2751                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2752                             }
2753                             return Def::Err;
2754                         }
2755                     }
2756                 }
2757             }
2758             Def::TyParam(..) | Def::SelfTy(..) => {
2759                 for rib in ribs {
2760                     match rib.kind {
2761                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2762                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2763                         ConstantItemRibKind => {
2764                             // Nothing to do. Continue.
2765                         }
2766                         ItemRibKind => {
2767                             // This was an attempt to use a type parameter outside
2768                             // its scope.
2769                             if record_used {
2770                                 resolve_error(self, span,
2771                                               ResolutionError::TypeParametersFromOuterFunction);
2772                             }
2773                             return Def::Err;
2774                         }
2775                     }
2776                 }
2777             }
2778             _ => {}
2779         }
2780         return def;
2781     }
2782
2783     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2784     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2785     // FIXME #34673: This needs testing.
2786     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2787         where F: FnOnce(&mut Resolver<'a>) -> T,
2788     {
2789         self.with_empty_ribs(|this| {
2790             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2791             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2792             f(this)
2793         })
2794     }
2795
2796     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2797         where F: FnOnce(&mut Resolver<'a>) -> T,
2798     {
2799         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2800         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2801
2802         let result = f(self);
2803         self.ribs = ribs;
2804         self.label_ribs = label_ribs;
2805         result
2806     }
2807
2808     fn lookup_assoc_candidate<FilterFn>(&mut self,
2809                                         name: Name,
2810                                         ns: Namespace,
2811                                         filter_fn: FilterFn)
2812                                         -> Option<AssocSuggestion>
2813         where FilterFn: Fn(Def) -> bool
2814     {
2815         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2816             match t.node {
2817                 TyKind::Path(None, _) => Some(t.id),
2818                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2819                 // This doesn't handle the remaining `Ty` variants as they are not
2820                 // that commonly the self_type, it might be interesting to provide
2821                 // support for those in future.
2822                 _ => None,
2823             }
2824         }
2825
2826         // Fields are generally expected in the same contexts as locals.
2827         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
2828             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
2829                 // Look for a field with the same name in the current self_type.
2830                 if let Some(resolution) = self.def_map.get(&node_id) {
2831                     match resolution.base_def() {
2832                         Def::Struct(did) | Def::Union(did)
2833                                 if resolution.unresolved_segments() == 0 => {
2834                             if let Some(field_names) = self.field_names.get(&did) {
2835                                 if field_names.iter().any(|&field_name| name == field_name) {
2836                                     return Some(AssocSuggestion::Field);
2837                                 }
2838                             }
2839                         }
2840                         _ => {}
2841                     }
2842                 }
2843             }
2844         }
2845
2846         // Look for associated items in the current trait.
2847         if let Some((trait_did, _)) = self.current_trait_ref {
2848             if let Some(&(def, has_self)) = self.trait_item_map.get(&(trait_did, name, ns)) {
2849                 if filter_fn(def) {
2850                     return Some(if has_self {
2851                         AssocSuggestion::MethodWithSelf
2852                     } else {
2853                         AssocSuggestion::AssocItem
2854                     });
2855                 }
2856             }
2857         }
2858
2859         None
2860     }
2861
2862     fn lookup_typo_candidate<FilterFn>(&mut self,
2863                                        path: &[Ident],
2864                                        ns: Namespace,
2865                                        filter_fn: FilterFn,
2866                                        span: Span)
2867                                        -> Option<Symbol>
2868         where FilterFn: Fn(Def) -> bool
2869     {
2870         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
2871             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
2872                 if let Some(binding) = resolution.borrow().binding {
2873                     if filter_fn(binding.def()) {
2874                         names.push(ident.name);
2875                     }
2876                 }
2877             }
2878         };
2879
2880         let mut names = Vec::new();
2881         if path.len() == 1 {
2882             // Search in lexical scope.
2883             // Walk backwards up the ribs in scope and collect candidates.
2884             for rib in self.ribs[ns].iter().rev() {
2885                 // Locals and type parameters
2886                 for (ident, def) in &rib.bindings {
2887                     if filter_fn(*def) {
2888                         names.push(ident.name);
2889                     }
2890                 }
2891                 // Items in scope
2892                 if let ModuleRibKind(module) = rib.kind {
2893                     // Items from this module
2894                     add_module_candidates(module, &mut names);
2895
2896                     if let ModuleKind::Block(..) = module.kind {
2897                         // We can see through blocks
2898                     } else {
2899                         // Items from the prelude
2900                         if let Some(prelude) = self.prelude {
2901                             if !module.no_implicit_prelude {
2902                                 add_module_candidates(prelude, &mut names);
2903                             }
2904                         }
2905                         break;
2906                     }
2907                 }
2908             }
2909             // Add primitive types to the mix
2910             if filter_fn(Def::PrimTy(TyBool)) {
2911                 for (name, _) in &self.primitive_type_table.primitive_types {
2912                     names.push(*name);
2913                 }
2914             }
2915         } else {
2916             // Search in module.
2917             let mod_path = &path[..path.len() - 1];
2918             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS),
2919                                                                   false, span) {
2920                 add_module_candidates(module, &mut names);
2921             }
2922         }
2923
2924         let name = path[path.len() - 1].name;
2925         // Make sure error reporting is deterministic.
2926         names.sort_by_key(|name| name.as_str());
2927         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
2928             Some(found) if found != name => Some(found),
2929             _ => None,
2930         }
2931     }
2932
2933     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
2934         where F: FnOnce(&mut Resolver)
2935     {
2936         if let Some(label) = label {
2937             let def = Def::Label(id);
2938             self.with_label_rib(|this| {
2939                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
2940                 f(this);
2941             });
2942         } else {
2943             f(self);
2944         }
2945     }
2946
2947     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
2948         self.with_resolved_label(label, id, |this| this.visit_block(block));
2949     }
2950
2951     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
2952         // First, record candidate traits for this expression if it could
2953         // result in the invocation of a method call.
2954
2955         self.record_candidate_traits_for_expr_if_necessary(expr);
2956
2957         // Next, resolve the node.
2958         match expr.node {
2959             ExprKind::Path(ref qself, ref path) => {
2960                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
2961                 visit::walk_expr(self, expr);
2962             }
2963
2964             ExprKind::Struct(ref path, ..) => {
2965                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
2966                 visit::walk_expr(self, expr);
2967             }
2968
2969             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
2970                 match self.search_label(label.node) {
2971                     None => {
2972                         self.record_def(expr.id, err_path_resolution());
2973                         resolve_error(self,
2974                                       label.span,
2975                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
2976                     }
2977                     Some(def @ Def::Label(_)) => {
2978                         // Since this def is a label, it is never read.
2979                         self.record_def(expr.id, PathResolution::new(def));
2980                     }
2981                     Some(_) => {
2982                         span_bug!(expr.span, "label wasn't mapped to a label def!");
2983                     }
2984                 }
2985
2986                 // visit `break` argument if any
2987                 visit::walk_expr(self, expr);
2988             }
2989
2990             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
2991                 self.visit_expr(subexpression);
2992
2993                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2994                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
2995                 self.visit_block(if_block);
2996                 self.ribs[ValueNS].pop();
2997
2998                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
2999             }
3000
3001             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3002
3003             ExprKind::While(ref subexpression, ref block, label) => {
3004                 self.with_resolved_label(label, expr.id, |this| {
3005                     this.visit_expr(subexpression);
3006                     this.visit_block(block);
3007                 });
3008             }
3009
3010             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
3011                 self.with_resolved_label(label, expr.id, |this| {
3012                     this.visit_expr(subexpression);
3013                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
3014                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
3015                     this.visit_block(block);
3016                     this.ribs[ValueNS].pop();
3017                 });
3018             }
3019
3020             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
3021                 self.visit_expr(subexpression);
3022                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3023                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
3024
3025                 self.resolve_labeled_block(label, expr.id, block);
3026
3027                 self.ribs[ValueNS].pop();
3028             }
3029
3030             // Equivalent to `visit::walk_expr` + passing some context to children.
3031             ExprKind::Field(ref subexpression, _) => {
3032                 self.resolve_expr(subexpression, Some(expr));
3033             }
3034             ExprKind::MethodCall(_, ref types, ref arguments) => {
3035                 let mut arguments = arguments.iter();
3036                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3037                 for argument in arguments {
3038                     self.resolve_expr(argument, None);
3039                 }
3040                 for ty in types.iter() {
3041                     self.visit_ty(ty);
3042                 }
3043             }
3044
3045             ExprKind::Repeat(ref element, ref count) => {
3046                 self.visit_expr(element);
3047                 self.with_constant_rib(|this| {
3048                     this.visit_expr(count);
3049                 });
3050             }
3051             ExprKind::Call(ref callee, ref arguments) => {
3052                 self.resolve_expr(callee, Some(expr));
3053                 for argument in arguments {
3054                     self.resolve_expr(argument, None);
3055                 }
3056             }
3057
3058             _ => {
3059                 visit::walk_expr(self, expr);
3060             }
3061         }
3062     }
3063
3064     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3065         match expr.node {
3066             ExprKind::Field(_, name) => {
3067                 // FIXME(#6890): Even though you can't treat a method like a
3068                 // field, we need to add any trait methods we find that match
3069                 // the field name so that we can do some nice error reporting
3070                 // later on in typeck.
3071                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3072                 self.trait_map.insert(expr.id, traits);
3073             }
3074             ExprKind::MethodCall(name, ..) => {
3075                 debug!("(recording candidate traits for expr) recording traits for {}",
3076                        expr.id);
3077                 let traits = self.get_traits_containing_item(name.node.name, ValueNS);
3078                 self.trait_map.insert(expr.id, traits);
3079             }
3080             _ => {
3081                 // Nothing to do.
3082             }
3083         }
3084     }
3085
3086     fn get_traits_containing_item(&mut self, name: Name, ns: Namespace) -> Vec<TraitCandidate> {
3087         debug!("(getting traits containing item) looking for '{}'", name);
3088
3089         let mut found_traits = Vec::new();
3090         // Look for the current trait.
3091         if let Some((trait_def_id, _)) = self.current_trait_ref {
3092             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3093                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: None });
3094             }
3095         }
3096
3097         let mut search_module = self.current_module;
3098         loop {
3099             self.get_traits_in_module_containing_item(name, ns, search_module, &mut found_traits);
3100             match search_module.kind {
3101                 ModuleKind::Block(..) => search_module = search_module.parent.unwrap(),
3102                 _ => break,
3103             }
3104         }
3105
3106         if let Some(prelude) = self.prelude {
3107             if !search_module.no_implicit_prelude {
3108                 self.get_traits_in_module_containing_item(name, ns, prelude, &mut found_traits);
3109             }
3110         }
3111
3112         found_traits
3113     }
3114
3115     fn get_traits_in_module_containing_item(&mut self,
3116                                             name: Name,
3117                                             ns: Namespace,
3118                                             module: Module,
3119                                             found_traits: &mut Vec<TraitCandidate>) {
3120         let mut traits = module.traits.borrow_mut();
3121         if traits.is_none() {
3122             let mut collected_traits = Vec::new();
3123             module.for_each_child(|name, ns, binding| {
3124                 if ns != TypeNS { return }
3125                 if let Def::Trait(_) = binding.def() {
3126                     collected_traits.push((name, binding));
3127                 }
3128             });
3129             *traits = Some(collected_traits.into_boxed_slice());
3130         }
3131
3132         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3133             let trait_def_id = binding.def().def_id();
3134             if self.trait_item_map.contains_key(&(trait_def_id, name, ns)) {
3135                 let import_id = match binding.kind {
3136                     NameBindingKind::Import { directive, .. } => {
3137                         self.maybe_unused_trait_imports.insert(directive.id);
3138                         self.add_to_glob_map(directive.id, trait_name);
3139                         Some(directive.id)
3140                     }
3141                     _ => None,
3142                 };
3143                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3144             }
3145         }
3146     }
3147
3148     /// When name resolution fails, this method can be used to look up candidate
3149     /// entities with the expected name. It allows filtering them using the
3150     /// supplied predicate (which should be used to only accept the types of
3151     /// definitions expected e.g. traits). The lookup spans across all crates.
3152     ///
3153     /// NOTE: The method does not look into imports, but this is not a problem,
3154     /// since we report the definitions (thus, the de-aliased imports).
3155     fn lookup_import_candidates<FilterFn>(&mut self,
3156                                           lookup_name: Name,
3157                                           namespace: Namespace,
3158                                           filter_fn: FilterFn)
3159                                           -> Vec<ImportSuggestion>
3160         where FilterFn: Fn(Def) -> bool
3161     {
3162         let mut candidates = Vec::new();
3163         let mut worklist = Vec::new();
3164         let mut seen_modules = FxHashSet();
3165         worklist.push((self.graph_root, Vec::new(), false));
3166
3167         while let Some((in_module,
3168                         path_segments,
3169                         in_module_is_extern)) = worklist.pop() {
3170             self.populate_module_if_necessary(in_module);
3171
3172             in_module.for_each_child(|ident, ns, name_binding| {
3173
3174                 // avoid imports entirely
3175                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3176                 // avoid non-importable candidates as well
3177                 if !name_binding.is_importable() { return; }
3178
3179                 // collect results based on the filter function
3180                 if ident.name == lookup_name && ns == namespace {
3181                     if filter_fn(name_binding.def()) {
3182                         // create the path
3183                         let mut segms = path_segments.clone();
3184                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3185                         let path = Path {
3186                             span: name_binding.span,
3187                             segments: segms,
3188                         };
3189                         // the entity is accessible in the following cases:
3190                         // 1. if it's defined in the same crate, it's always
3191                         // accessible (since private entities can be made public)
3192                         // 2. if it's defined in another crate, it's accessible
3193                         // only if both the module is public and the entity is
3194                         // declared as public (due to pruning, we don't explore
3195                         // outside crate private modules => no need to check this)
3196                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3197                             candidates.push(ImportSuggestion { path: path });
3198                         }
3199                     }
3200                 }
3201
3202                 // collect submodules to explore
3203                 if let Some(module) = name_binding.module() {
3204                     // form the path
3205                     let mut path_segments = path_segments.clone();
3206                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3207
3208                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3209                         // add the module to the lookup
3210                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3211                         if seen_modules.insert(module.def_id().unwrap()) {
3212                             worklist.push((module, path_segments, is_extern));
3213                         }
3214                     }
3215                 }
3216             })
3217         }
3218
3219         candidates
3220     }
3221
3222     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3223         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3224         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3225             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3226         }
3227     }
3228
3229     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3230         match *vis {
3231             ast::Visibility::Public => ty::Visibility::Public,
3232             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3233             ast::Visibility::Inherited => {
3234                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3235             }
3236             ast::Visibility::Restricted { ref path, id } => {
3237                 let def = self.smart_resolve_path(id, None, path,
3238                                                   PathSource::Visibility).base_def();
3239                 if def == Def::Err {
3240                     ty::Visibility::Public
3241                 } else {
3242                     let vis = ty::Visibility::Restricted(def.def_id());
3243                     if self.is_accessible(vis) {
3244                         vis
3245                     } else {
3246                         self.session.span_err(path.span, "visibilities can only be restricted \
3247                                                           to ancestor modules");
3248                         ty::Visibility::Public
3249                     }
3250                 }
3251             }
3252         }
3253     }
3254
3255     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3256         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3257     }
3258
3259     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3260         vis.is_accessible_from(module.normal_ancestor_id, self)
3261     }
3262
3263     fn report_errors(&mut self) {
3264         self.report_shadowing_errors();
3265         let mut reported_spans = FxHashSet();
3266
3267         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3268             if !reported_spans.insert(span) { continue }
3269             let participle = |binding: &NameBinding| {
3270                 if binding.is_import() { "imported" } else { "defined" }
3271             };
3272             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3273             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3274             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3275                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3276             } else if let Def::Macro(..) = b1.def() {
3277                 format!("macro-expanded {} do not shadow",
3278                         if b1.is_import() { "macro imports" } else { "macros" })
3279             } else {
3280                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3281                         if b1.is_import() { "imports" } else { "items" })
3282             };
3283             if legacy {
3284                 let id = match b2.kind {
3285                     NameBindingKind::Import { directive, .. } => directive.id,
3286                     _ => unreachable!(),
3287                 };
3288                 let mut span = MultiSpan::from_span(span);
3289                 span.push_span_label(b1.span, msg1);
3290                 span.push_span_label(b2.span, msg2);
3291                 let msg = format!("`{}` is ambiguous", name);
3292                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3293             } else {
3294                 let mut err =
3295                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3296                 err.span_note(b1.span, &msg1);
3297                 match b2.def() {
3298                     Def::Macro(..) if b2.span == DUMMY_SP =>
3299                         err.note(&format!("`{}` is also a builtin macro", name)),
3300                     _ => err.span_note(b2.span, &msg2),
3301                 };
3302                 err.note(&note).emit();
3303             }
3304         }
3305
3306         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3307             if !reported_spans.insert(span) { continue }
3308             if binding.is_extern_crate() {
3309                 // Warn when using an inaccessible extern crate.
3310                 let node_id = match binding.kind {
3311                     NameBindingKind::Import { directive, .. } => directive.id,
3312                     _ => unreachable!(),
3313                 };
3314                 let msg = format!("extern crate `{}` is private", name);
3315                 self.session.add_lint(lint::builtin::INACCESSIBLE_EXTERN_CRATE, node_id, span, msg);
3316             } else {
3317                 let def = binding.def();
3318                 self.session.span_err(span, &format!("{} `{}` is private", def.kind_name(), name));
3319             }
3320         }
3321     }
3322
3323     fn report_shadowing_errors(&mut self) {
3324         for (name, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3325             self.resolve_legacy_scope(scope, name, true);
3326         }
3327
3328         let mut reported_errors = FxHashSet();
3329         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3330             if self.resolve_legacy_scope(&binding.parent, binding.name, false).is_some() &&
3331                reported_errors.insert((binding.name, binding.span)) {
3332                 let msg = format!("`{}` is already in scope", binding.name);
3333                 self.session.struct_span_err(binding.span, &msg)
3334                     .note("macro-expanded `macro_rules!`s may not shadow \
3335                            existing macros (see RFC 1560)")
3336                     .emit();
3337             }
3338         }
3339     }
3340
3341     fn report_conflict(&mut self,
3342                        parent: Module,
3343                        ident: Ident,
3344                        ns: Namespace,
3345                        binding: &NameBinding,
3346                        old_binding: &NameBinding) {
3347         // Error on the second of two conflicting names
3348         if old_binding.span.lo > binding.span.lo {
3349             return self.report_conflict(parent, ident, ns, old_binding, binding);
3350         }
3351
3352         let container = match parent.kind {
3353             ModuleKind::Def(Def::Mod(_), _) => "module",
3354             ModuleKind::Def(Def::Trait(_), _) => "trait",
3355             ModuleKind::Block(..) => "block",
3356             _ => "enum",
3357         };
3358
3359         let (participle, noun) = match old_binding.is_import() {
3360             true => ("imported", "import"),
3361             false => ("defined", "definition"),
3362         };
3363
3364         let (name, span) = (ident.name, binding.span);
3365
3366         if let Some(s) = self.name_already_seen.get(&name) {
3367             if s == &span {
3368                 return;
3369             }
3370         }
3371
3372         let msg = {
3373             let kind = match (ns, old_binding.module()) {
3374                 (ValueNS, _) => "a value",
3375                 (MacroNS, _) => "a macro",
3376                 (TypeNS, _) if old_binding.is_extern_crate() => "an extern crate",
3377                 (TypeNS, Some(module)) if module.is_normal() => "a module",
3378                 (TypeNS, Some(module)) if module.is_trait() => "a trait",
3379                 (TypeNS, _) => "a type",
3380             };
3381             format!("{} named `{}` has already been {} in this {}",
3382                     kind, name, participle, container)
3383         };
3384
3385         let mut err = match (old_binding.is_extern_crate(), binding.is_extern_crate()) {
3386             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3387             (true, _) | (_, true) => match binding.is_import() && old_binding.is_import() {
3388                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3389                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3390             },
3391             _ => match (old_binding.is_import(), binding.is_import()) {
3392                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3393                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3394                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3395             },
3396         };
3397
3398         err.span_label(span, format!("`{}` already {}", name, participle));
3399         if old_binding.span != syntax_pos::DUMMY_SP {
3400             err.span_label(old_binding.span, format!("previous {} of `{}` here", noun, name));
3401         }
3402         err.emit();
3403         self.name_already_seen.insert(name, span);
3404     }
3405
3406     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3407         let (id, span) = (directive.id, directive.span);
3408         let msg = "`self` no longer imports values".to_string();
3409         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3410     }
3411
3412     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3413         if self.proc_macro_enabled { return; }
3414
3415         for attr in attrs {
3416             if attr.path.segments.len() > 1 {
3417                 continue
3418             }
3419             let ident = attr.path.segments[0].identifier;
3420             let result = self.resolve_lexical_macro_path_segment(ident,
3421                                                                  MacroNS,
3422                                                                  false,
3423                                                                  attr.path.span);
3424             if let Ok(binding) = result {
3425                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3426                     attr::mark_known(attr);
3427
3428                     let msg = "attribute procedural macros are experimental";
3429                     let feature = "proc_macro";
3430
3431                     feature_err(&self.session.parse_sess, feature,
3432                                 attr.span, GateIssue::Language, msg)
3433                         .span_note(binding.span(), "procedural macro imported here")
3434                         .emit();
3435                 }
3436             }
3437         }
3438     }
3439 }
3440
3441 fn is_struct_like(def: Def) -> bool {
3442     match def {
3443         Def::VariantCtor(_, CtorKind::Fictive) => true,
3444         _ => PathSource::Struct.is_expected(def),
3445     }
3446 }
3447
3448 fn is_self_type(path: &[Ident], namespace: Namespace) -> bool {
3449     namespace == TypeNS && path.len() == 1 && path[0].name == keywords::SelfType.name()
3450 }
3451
3452 fn is_self_value(path: &[Ident], namespace: Namespace) -> bool {
3453     namespace == ValueNS && path.len() == 1 && path[0].name == keywords::SelfValue.name()
3454 }
3455
3456 fn names_to_string(idents: &[Ident]) -> String {
3457     let mut result = String::new();
3458     for (i, ident) in idents.iter().filter(|i| i.name != keywords::CrateRoot.name()).enumerate() {
3459         if i > 0 {
3460             result.push_str("::");
3461         }
3462         result.push_str(&ident.name.as_str());
3463     }
3464     result
3465 }
3466
3467 fn path_names_to_string(path: &Path) -> String {
3468     names_to_string(&path.segments.iter().map(|seg| seg.identifier).collect::<Vec<_>>())
3469 }
3470
3471 /// Get the path for an enum and the variant from an `ImportSuggestion` for an enum variant.
3472 fn import_candidate_to_paths(suggestion: &ImportSuggestion) -> (Span, String, String) {
3473     let variant_path = &suggestion.path;
3474     let variant_path_string = path_names_to_string(variant_path);
3475
3476     let path_len = suggestion.path.segments.len();
3477     let enum_path = ast::Path {
3478         span: suggestion.path.span,
3479         segments: suggestion.path.segments[0..path_len - 1].to_vec(),
3480     };
3481     let enum_path_string = path_names_to_string(&enum_path);
3482
3483     (suggestion.path.span, variant_path_string, enum_path_string)
3484 }
3485
3486
3487 /// When an entity with a given name is not available in scope, we search for
3488 /// entities with that name in all crates. This method allows outputting the
3489 /// results of this search in a programmer-friendly way
3490 fn show_candidates(err: &mut DiagnosticBuilder,
3491                    span: Span,
3492                    candidates: &[ImportSuggestion],
3493                    better: bool) {
3494
3495     // we want consistent results across executions, but candidates are produced
3496     // by iterating through a hash map, so make sure they are ordered:
3497     let mut path_strings: Vec<_> =
3498         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3499     path_strings.sort();
3500
3501     let better = if better { "better " } else { "" };
3502     let msg_diff = match path_strings.len() {
3503         1 => " is found in another module, you can import it",
3504         _ => "s are found in other modules, you can import them",
3505     };
3506     let msg = format!("possible {}candidate{} into scope", better, msg_diff);
3507
3508     for candidate in &mut path_strings {
3509         *candidate = format!("use {};\n", candidate);
3510     }
3511
3512     err.span_suggestions(span, &msg, path_strings);
3513 }
3514
3515 /// A somewhat inefficient routine to obtain the name of a module.
3516 fn module_to_string(module: Module) -> String {
3517     let mut names = Vec::new();
3518
3519     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3520         if let ModuleKind::Def(_, name) = module.kind {
3521             if let Some(parent) = module.parent {
3522                 names.push(Ident::with_empty_ctxt(name));
3523                 collect_mod(names, parent);
3524             }
3525         } else {
3526             // danger, shouldn't be ident?
3527             names.push(Ident::from_str("<opaque>"));
3528             collect_mod(names, module.parent.unwrap());
3529         }
3530     }
3531     collect_mod(&mut names, module);
3532
3533     if names.is_empty() {
3534         return "???".to_string();
3535     }
3536     names_to_string(&names.into_iter().rev().collect::<Vec<_>>())
3537 }
3538
3539 fn err_path_resolution() -> PathResolution {
3540     PathResolution::new(Def::Err)
3541 }
3542
3543 #[derive(PartialEq,Copy, Clone)]
3544 pub enum MakeGlobMap {
3545     Yes,
3546     No,
3547 }
3548
3549 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }