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(rustc_diagnostic_macros)]
  20
  21 #[macro_use]
  22 extern crate log;
  23 #[macro_use]
  24 extern crate syntax;
  25 extern crate syntax_pos;
  26 extern crate rustc_errors as errors;
  27 extern crate arena;
  28 #[macro_use]
  29 extern crate rustc;
  30
  31 use self::Namespace::*;
  32 use self::TypeParameters::*;
  33 use self::RibKind::*;
  34
  35 use rustc::hir::map::{Definitions, DefCollector};
  36 use rustc::hir::{self, PrimTy, TyBool, TyChar, TyFloat, TyInt, TyUint, TyStr};
  37 use rustc::middle::cstore::CrateLoader;
  38 use rustc::session::Session;
  39 use rustc::lint;
  40 use rustc::hir::def::*;
  41 use rustc::hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
  42 use rustc::ty;
  43 use rustc::hir::{Freevar, FreevarMap, TraitCandidate, TraitMap, GlobMap};
  44 use rustc::util::nodemap::{NodeMap, NodeSet, FxHashMap, FxHashSet, DefIdMap};
  45
  46 use syntax::codemap::{dummy_spanned, respan};
  47 use syntax::ext::hygiene::{Mark, SyntaxContext};
  48 use syntax::ast::{self, Name, NodeId, Ident, SpannedIdent, FloatTy, IntTy, UintTy};
  49 use syntax::ext::base::SyntaxExtension;
  50 use syntax::ext::base::Determinacy::{self, Determined, Undetermined};
  51 use syntax::ext::base::MacroKind;
  52 use syntax::symbol::{Symbol, keywords};
  53 use syntax::util::lev_distance::find_best_match_for_name;
  54
  55 use syntax::visit::{self, FnKind, Visitor};
  56 use syntax::attr;
  57 use syntax::ast::{Arm, BindingMode, Block, Crate, Expr, ExprKind};
  58 use syntax::ast::{FnDecl, ForeignItem, ForeignItemKind, Generics};
  59 use syntax::ast::{Item, ItemKind, ImplItem, ImplItemKind};
  60 use syntax::ast::{Local, Mutability, Pat, PatKind, Path};
  61 use syntax::ast::{QSelf, TraitItemKind, TraitRef, Ty, TyKind};
  62 use syntax::feature_gate::{feature_err, emit_feature_err, GateIssue};
  63
  64 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  65 use errors::DiagnosticBuilder;
  66
  67 use std::cell::{Cell, RefCell};
  68 use std::cmp;
  69 use std::collections::BTreeSet;
  70 use std::fmt;
  71 use std::mem::replace;
  72 use std::rc::Rc;
  73
  74 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
  75 use macros::{InvocationData, LegacyBinding, LegacyScope, MacroBinding};
  76
  77 // NB: This module needs to be declared first so diagnostics are
  78 // registered before they are used.
  79 mod diagnostics;
  80
  81 mod macros;
  82 mod check_unused;
  83 mod build_reduced_graph;
  84 mod resolve_imports;
  85
  86 /// A free importable items suggested in case of resolution failure.
  87 struct ImportSuggestion {
  88     path: Path,
  89 }
  90
  91 /// A field or associated item from self type suggested in case of resolution failure.
  92 enum AssocSuggestion {
  93     Field,
  94     MethodWithSelf,
  95     AssocItem,
  96 }
  97
  98 #[derive(Eq)]
  99 struct BindingError {
 100     name: Name,
 101     origin: BTreeSet<Span>,
 102     target: BTreeSet<Span>,
 103 }
 104
 105 impl PartialOrd for BindingError {
 106     fn partial_cmp(&self, other: &BindingError) -> Option<cmp::Ordering> {
 107         Some(self.cmp(other))
 108     }
 109 }
 110
 111 impl PartialEq for BindingError {
 112     fn eq(&self, other: &BindingError) -> bool {
 113         self.name == other.name
 114     }
 115 }
 116
 117 impl Ord for BindingError {
 118     fn cmp(&self, other: &BindingError) -> cmp::Ordering {
 119         self.name.cmp(&other.name)
 120     }
 121 }
 122
 123 enum ResolutionError<'a> {
 124     /// error E0401: can't use type parameters from outer function
 125     TypeParametersFromOuterFunction,
 126     /// error E0403: the name is already used for a type parameter in this type parameter list
 127     NameAlreadyUsedInTypeParameterList(Name, &'a Span),
 128     /// error E0407: method is not a member of trait
 129     MethodNotMemberOfTrait(Name, &'a str),
 130     /// error E0437: type is not a member of trait
 131     TypeNotMemberOfTrait(Name, &'a str),
 132     /// error E0438: const is not a member of trait
 133     ConstNotMemberOfTrait(Name, &'a str),
 134     /// error E0408: variable `{}` is not bound in all patterns
 135     VariableNotBoundInPattern(&'a BindingError),
 136     /// error E0409: variable `{}` is bound in inconsistent ways within the same match arm
 137     VariableBoundWithDifferentMode(Name, Span),
 138     /// error E0415: identifier is bound more than once in this parameter list
 139     IdentifierBoundMoreThanOnceInParameterList(&'a str),
 140     /// error E0416: identifier is bound more than once in the same pattern
 141     IdentifierBoundMoreThanOnceInSamePattern(&'a str),
 142     /// error E0426: use of undeclared label
 143     UndeclaredLabel(&'a str),
 144     /// error E0429: `self` imports are only allowed within a { } list
 145     SelfImportsOnlyAllowedWithin,
 146     /// error E0430: `self` import can only appear once in the list
 147     SelfImportCanOnlyAppearOnceInTheList,
 148     /// error E0431: `self` import can only appear in an import list with a non-empty prefix
 149     SelfImportOnlyInImportListWithNonEmptyPrefix,
 150     /// error E0432: unresolved import
 151     UnresolvedImport(Option<(Span, &'a str, &'a str)>),
 152     /// error E0433: failed to resolve
 153     FailedToResolve(&'a str),
 154     /// error E0434: can't capture dynamic environment in a fn item
 155     CannotCaptureDynamicEnvironmentInFnItem,
 156     /// error E0435: attempt to use a non-constant value in a constant
 157     AttemptToUseNonConstantValueInConstant,
 158     /// error E0530: X bindings cannot shadow Ys
 159     BindingShadowsSomethingUnacceptable(&'a str, Name, &'a NameBinding<'a>),
 160     /// error E0128: type parameters with a default cannot use forward declared identifiers
 161     ForwardDeclaredTyParam,
 162 }
 163
 164 fn resolve_error<'sess, 'a>(resolver: &'sess Resolver,
 165                             span: Span,
 166                             resolution_error: ResolutionError<'a>) {
 167     resolve_struct_error(resolver, span, resolution_error).emit();
 168 }
 169
 170 fn resolve_struct_error<'sess, 'a>(resolver: &'sess Resolver,
 171                                    span: Span,
 172                                    resolution_error: ResolutionError<'a>)
 173                                    -> DiagnosticBuilder<'sess> {
 174     match resolution_error {
 175         ResolutionError::TypeParametersFromOuterFunction => {
 176             let mut err = struct_span_err!(resolver.session,
 177                                            span,
 178                                            E0401,
 179                                            "can't use type parameters from outer function; \
 180                                            try using a local type parameter instead");
 181             err.span_label(span, "use of type variable from outer function");
 182             err
 183         }
 184         ResolutionError::NameAlreadyUsedInTypeParameterList(name, first_use_span) => {
 185              let mut err = struct_span_err!(resolver.session,
 186                                             span,
 187                                             E0403,
 188                                             "the name `{}` is already used for a type parameter \
 189                                             in this type parameter list",
 190                                             name);
 191              err.span_label(span, "already used");
 192              err.span_label(first_use_span.clone(), format!("first use of `{}`", name));
 193              err
 194         }
 195         ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
 196             let mut err = struct_span_err!(resolver.session,
 197                                            span,
 198                                            E0407,
 199                                            "method `{}` is not a member of trait `{}`",
 200                                            method,
 201                                            trait_);
 202             err.span_label(span, format!("not a member of trait `{}`", trait_));
 203             err
 204         }
 205         ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
 206             let mut err = struct_span_err!(resolver.session,
 207                              span,
 208                              E0437,
 209                              "type `{}` is not a member of trait `{}`",
 210                              type_,
 211                              trait_);
 212             err.span_label(span, format!("not a member of trait `{}`", trait_));
 213             err
 214         }
 215         ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
 216             let mut err = struct_span_err!(resolver.session,
 217                              span,
 218                              E0438,
 219                              "const `{}` is not a member of trait `{}`",
 220                              const_,
 221                              trait_);
 222             err.span_label(span, format!("not a member of trait `{}`", trait_));
 223             err
 224         }
 225         ResolutionError::VariableNotBoundInPattern(binding_error) => {
 226             let target_sp = binding_error.target.iter().map(|x| *x).collect::<Vec<_>>();
 227             let msp = MultiSpan::from_spans(target_sp.clone());
 228             let msg = format!("variable `{}` is not bound in all patterns", binding_error.name);
 229             let mut err = resolver.session.struct_span_err_with_code(msp, &msg, "E0408");
 230             for sp in target_sp {
 231                 err.span_label(sp, format!("pattern doesn't bind `{}`", binding_error.name));
 232             }
 233             let origin_sp = binding_error.origin.iter().map(|x| *x).collect::<Vec<_>>();
 234             for sp in origin_sp {
 235                 err.span_label(sp, "variable not in all patterns");
 236             }
 237             err
 238         }
 239         ResolutionError::VariableBoundWithDifferentMode(variable_name,
 240                                                         first_binding_span) => {
 241             let mut err = struct_span_err!(resolver.session,
 242                              span,
 243                              E0409,
 244                              "variable `{}` is bound in inconsistent \
 245                              ways within the same match arm",
 246                              variable_name);
 247             err.span_label(span, "bound in different ways");
 248             err.span_label(first_binding_span, "first binding");
 249             err
 250         }
 251         ResolutionError::IdentifierBoundMoreThanOnceInParameterList(identifier) => {
 252             let mut err = struct_span_err!(resolver.session,
 253                              span,
 254                              E0415,
 255                              "identifier `{}` is bound more than once in this parameter list",
 256                              identifier);
 257             err.span_label(span, "used as parameter more than once");
 258             err
 259         }
 260         ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(identifier) => {
 261             let mut err = struct_span_err!(resolver.session,
 262                              span,
 263                              E0416,
 264                              "identifier `{}` is bound more than once in the same pattern",
 265                              identifier);
 266             err.span_label(span, "used in a pattern more than once");
 267             err
 268         }
 269         ResolutionError::UndeclaredLabel(name) => {
 270             let mut err = struct_span_err!(resolver.session,
 271                                            span,
 272                                            E0426,
 273                                            "use of undeclared label `{}`",
 274                                            name);
 275             err.span_label(span, format!("undeclared label `{}`", name));
 276             err
 277         }
 278         ResolutionError::SelfImportsOnlyAllowedWithin => {
 279             struct_span_err!(resolver.session,
 280                              span,
 281                              E0429,
 282                              "{}",
 283                              "`self` imports are only allowed within a { } list")
 284         }
 285         ResolutionError::SelfImportCanOnlyAppearOnceInTheList => {
 286             struct_span_err!(resolver.session,
 287                              span,
 288                              E0430,
 289                              "`self` import can only appear once in the list")
 290         }
 291         ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
 292             struct_span_err!(resolver.session,
 293                              span,
 294                              E0431,
 295                              "`self` import can only appear in an import list with a \
 296                               non-empty prefix")
 297         }
 298         ResolutionError::UnresolvedImport(name) => {
 299             let (span, msg) = match name {
 300                 Some((sp, n, _)) => (sp, format!("unresolved import `{}`", n)),
 301                 None => (span, "unresolved import".to_owned()),
 302             };
 303             let mut err = struct_span_err!(resolver.session, span, E0432, "{}", msg);
 304             if let Some((_, _, p)) = name {
 305                 err.span_label(span, p);
 306             }
 307             err
 308         }
 309         ResolutionError::FailedToResolve(msg) => {
 310             let mut err = struct_span_err!(resolver.session, span, E0433,
 311                                            "failed to resolve. {}", msg);
 312             err.span_label(span, msg);
 313             err
 314         }
 315         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem => {
 316             struct_span_err!(resolver.session,
 317                              span,
 318                              E0434,
 319                              "{}",
 320                              "can't capture dynamic environment in a fn item; use the || { ... } \
 321                               closure form instead")
 322         }
 323         ResolutionError::AttemptToUseNonConstantValueInConstant => {
 324             let mut err = struct_span_err!(resolver.session,
 325                              span,
 326                              E0435,
 327                              "attempt to use a non-constant value in a constant");
 328             err.span_label(span, "non-constant value");
 329             err
 330         }
 331         ResolutionError::BindingShadowsSomethingUnacceptable(what_binding, name, binding) => {
 332             let shadows_what = PathResolution::new(binding.def()).kind_name();
 333             let mut err = struct_span_err!(resolver.session,
 334                                            span,
 335                                            E0530,
 336                                            "{}s cannot shadow {}s", what_binding, shadows_what);
 337             err.span_label(span, format!("cannot be named the same as a {}", shadows_what));
 338             let participle = if binding.is_import() { "imported" } else { "defined" };
 339             let msg = format!("a {} `{}` is {} here", shadows_what, name, participle);
 340             err.span_label(binding.span, msg);
 341             err
 342         }
 343         ResolutionError::ForwardDeclaredTyParam => {
 344             let mut err = struct_span_err!(resolver.session, span, E0128,
 345                                            "type parameters with a default cannot use \
 346                                             forward declared identifiers");
 347             err.span_label(span, format!("defaulted type parameters \
 348                                            cannot be forward declared"));
 349             err
 350         }
 351     }
 352 }
 353
 354 #[derive(Copy, Clone, Debug)]
 355 struct BindingInfo {
 356     span: Span,
 357     binding_mode: BindingMode,
 358 }
 359
 360 // Map from the name in a pattern to its binding mode.
 361 type BindingMap = FxHashMap<Ident, BindingInfo>;
 362
 363 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 364 enum PatternSource {
 365     Match,
 366     IfLet,
 367     WhileLet,
 368     Let,
 369     For,
 370     FnParam,
 371 }
 372
 373 impl PatternSource {
 374     fn is_refutable(self) -> bool {
 375         match self {
 376             PatternSource::Match | PatternSource::IfLet | PatternSource::WhileLet => true,
 377             PatternSource::Let | PatternSource::For | PatternSource::FnParam  => false,
 378         }
 379     }
 380     fn descr(self) -> &'static str {
 381         match self {
 382             PatternSource::Match => "match binding",
 383             PatternSource::IfLet => "if let binding",
 384             PatternSource::WhileLet => "while let binding",
 385             PatternSource::Let => "let binding",
 386             PatternSource::For => "for binding",
 387             PatternSource::FnParam => "function parameter",
 388         }
 389     }
 390 }
 391
 392 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 393 enum PathSource<'a> {
 394     // Type paths `Path`.
 395     Type,
 396     // Trait paths in bounds or impls.
 397     Trait,
 398     // Expression paths `path`, with optional parent context.
 399     Expr(Option<&'a Expr>),
 400     // Paths in path patterns `Path`.
 401     Pat,
 402     // Paths in struct expressions and patterns `Path { .. }`.
 403     Struct,
 404     // Paths in tuple struct patterns `Path(..)`.
 405     TupleStruct,
 406     // `m::A::B` in `<T as m::A>::B::C`.
 407     TraitItem(Namespace),
 408     // Path in `pub(path)`
 409     Visibility,
 410     // Path in `use a::b::{...};`
 411     ImportPrefix,
 412 }
 413
 414 impl<'a> PathSource<'a> {
 415     fn namespace(self) -> Namespace {
 416         match self {
 417             PathSource::Type | PathSource::Trait | PathSource::Struct |
 418             PathSource::Visibility | PathSource::ImportPrefix => TypeNS,
 419             PathSource::Expr(..) | PathSource::Pat | PathSource::TupleStruct => ValueNS,
 420             PathSource::TraitItem(ns) => ns,
 421         }
 422     }
 423
 424     fn global_by_default(self) -> bool {
 425         match self {
 426             PathSource::Visibility | PathSource::ImportPrefix => true,
 427             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 428             PathSource::Struct | PathSource::TupleStruct |
 429             PathSource::Trait | PathSource::TraitItem(..) => false,
 430         }
 431     }
 432
 433     fn defer_to_typeck(self) -> bool {
 434         match self {
 435             PathSource::Type | PathSource::Expr(..) | PathSource::Pat |
 436             PathSource::Struct | PathSource::TupleStruct => true,
 437             PathSource::Trait | PathSource::TraitItem(..) |
 438             PathSource::Visibility | PathSource::ImportPrefix => false,
 439         }
 440     }
 441
 442     fn descr_expected(self) -> &'static str {
 443         match self {
 444             PathSource::Type => "type",
 445             PathSource::Trait => "trait",
 446             PathSource::Pat => "unit struct/variant or constant",
 447             PathSource::Struct => "struct, variant or union type",
 448             PathSource::TupleStruct => "tuple struct/variant",
 449             PathSource::Visibility => "module",
 450             PathSource::ImportPrefix => "module or enum",
 451             PathSource::TraitItem(ns) => match ns {
 452                 TypeNS => "associated type",
 453                 ValueNS => "method or associated constant",
 454                 MacroNS => bug!("associated macro"),
 455             },
 456             PathSource::Expr(parent) => match parent.map(|p| &p.node) {
 457                 // "function" here means "anything callable" rather than `Def::Fn`,
 458                 // this is not precise but usually more helpful than just "value".
 459                 Some(&ExprKind::Call(..)) => "function",
 460                 _ => "value",
 461             },
 462         }
 463     }
 464
 465     fn is_expected(self, def: Def) -> bool {
 466         match self {
 467             PathSource::Type => match def {
 468                 Def::Struct(..) | Def::Union(..) | Def::Enum(..) |
 469                 Def::Trait(..) | Def::TyAlias(..) | Def::AssociatedTy(..) |
 470                 Def::PrimTy(..) | Def::TyParam(..) | Def::SelfTy(..) => true,
 471                 _ => false,
 472             },
 473             PathSource::Trait => match def {
 474                 Def::Trait(..) => true,
 475                 _ => false,
 476             },
 477             PathSource::Expr(..) => match def {
 478                 Def::StructCtor(_, CtorKind::Const) | Def::StructCtor(_, CtorKind::Fn) |
 479                 Def::VariantCtor(_, CtorKind::Const) | Def::VariantCtor(_, CtorKind::Fn) |
 480                 Def::Const(..) | Def::Static(..) | Def::Local(..) | Def::Upvar(..) |
 481                 Def::Fn(..) | Def::Method(..) | Def::AssociatedConst(..) => true,
 482                 _ => false,
 483             },
 484             PathSource::Pat => match def {
 485                 Def::StructCtor(_, CtorKind::Const) |
 486                 Def::VariantCtor(_, CtorKind::Const) |
 487                 Def::Const(..) | Def::AssociatedConst(..) => true,
 488                 _ => false,
 489             },
 490             PathSource::TupleStruct => match def {
 491                 Def::StructCtor(_, CtorKind::Fn) | Def::VariantCtor(_, CtorKind::Fn) => true,
 492                 _ => false,
 493             },
 494             PathSource::Struct => match def {
 495                 Def::Struct(..) | Def::Union(..) | Def::Variant(..) |
 496                 Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => true,
 497                 _ => false,
 498             },
 499             PathSource::TraitItem(ns) => match def {
 500                 Def::AssociatedConst(..) | Def::Method(..) if ns == ValueNS => true,
 501                 Def::AssociatedTy(..) if ns == TypeNS => true,
 502                 _ => false,
 503             },
 504             PathSource::ImportPrefix => match def {
 505                 Def::Mod(..) | Def::Enum(..) => true,
 506                 _ => false,
 507             },
 508             PathSource::Visibility => match def {
 509                 Def::Mod(..) => true,
 510                 _ => false,
 511             },
 512         }
 513     }
 514
 515     fn error_code(self, has_unexpected_resolution: bool) -> &'static str {
 516         __diagnostic_used!(E0404);
 517         __diagnostic_used!(E0405);
 518         __diagnostic_used!(E0412);
 519         __diagnostic_used!(E0422);
 520         __diagnostic_used!(E0423);
 521         __diagnostic_used!(E0425);
 522         __diagnostic_used!(E0531);
 523         __diagnostic_used!(E0532);
 524         __diagnostic_used!(E0573);
 525         __diagnostic_used!(E0574);
 526         __diagnostic_used!(E0575);
 527         __diagnostic_used!(E0576);
 528         __diagnostic_used!(E0577);
 529         __diagnostic_used!(E0578);
 530         match (self, has_unexpected_resolution) {
 531             (PathSource::Trait, true) => "E0404",
 532             (PathSource::Trait, false) => "E0405",
 533             (PathSource::Type, true) => "E0573",
 534             (PathSource::Type, false) => "E0412",
 535             (PathSource::Struct, true) => "E0574",
 536             (PathSource::Struct, false) => "E0422",
 537             (PathSource::Expr(..), true) => "E0423",
 538             (PathSource::Expr(..), false) => "E0425",
 539             (PathSource::Pat, true) | (PathSource::TupleStruct, true) => "E0532",
 540             (PathSource::Pat, false) | (PathSource::TupleStruct, false) => "E0531",
 541             (PathSource::TraitItem(..), true) => "E0575",
 542             (PathSource::TraitItem(..), false) => "E0576",
 543             (PathSource::Visibility, true) | (PathSource::ImportPrefix, true) => "E0577",
 544             (PathSource::Visibility, false) | (PathSource::ImportPrefix, false) => "E0578",
 545         }
 546     }
 547 }
 548
 549 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 550 pub enum Namespace {
 551     TypeNS,
 552     ValueNS,
 553     MacroNS,
 554 }
 555
 556 #[derive(Clone, Default, Debug)]
 557 pub struct PerNS<T> {
 558     value_ns: T,
 559     type_ns: T,
 560     macro_ns: Option<T>,
 561 }
 562
 563 impl<T> ::std::ops::Index<Namespace> for PerNS<T> {
 564     type Output = T;
 565     fn index(&self, ns: Namespace) -> &T {
 566         match ns {
 567             ValueNS => &self.value_ns,
 568             TypeNS => &self.type_ns,
 569             MacroNS => self.macro_ns.as_ref().unwrap(),
 570         }
 571     }
 572 }
 573
 574 impl<T> ::std::ops::IndexMut<Namespace> for PerNS<T> {
 575     fn index_mut(&mut self, ns: Namespace) -> &mut T {
 576         match ns {
 577             ValueNS => &mut self.value_ns,
 578             TypeNS => &mut self.type_ns,
 579             MacroNS => self.macro_ns.as_mut().unwrap(),
 580         }
 581     }
 582 }
 583
 584 impl<'a, 'tcx> Visitor<'tcx> for Resolver<'a> {
 585     fn visit_item(&mut self, item: &'tcx Item) {
 586         self.resolve_item(item);
 587     }
 588     fn visit_arm(&mut self, arm: &'tcx Arm) {
 589         self.resolve_arm(arm);
 590     }
 591     fn visit_block(&mut self, block: &'tcx Block) {
 592         self.resolve_block(block);
 593     }
 594     fn visit_expr(&mut self, expr: &'tcx Expr) {
 595         self.resolve_expr(expr, None);
 596     }
 597     fn visit_local(&mut self, local: &'tcx Local) {
 598         self.resolve_local(local);
 599     }
 600     fn visit_ty(&mut self, ty: &'tcx Ty) {
 601         match ty.node {
 602             TyKind::Path(ref qself, ref path) => {
 603                 self.smart_resolve_path(ty.id, qself.as_ref(), path, PathSource::Type);
 604             }
 605             TyKind::ImplicitSelf => {
 606                 let self_ty = keywords::SelfType.ident();
 607                 let def = self.resolve_ident_in_lexical_scope(self_ty, TypeNS, true, ty.span)
 608                               .map_or(Def::Err, |d| d.def());
 609                 self.record_def(ty.id, PathResolution::new(def));
 610             }
 611             TyKind::Array(ref element, ref length) => {
 612                 self.visit_ty(element);
 613                 self.with_constant_rib(|this| {
 614                     this.visit_expr(length);
 615                 });
 616                 return;
 617             }
 618             _ => (),
 619         }
 620         visit::walk_ty(self, ty);
 621     }
 622     fn visit_poly_trait_ref(&mut self,
 623                             tref: &'tcx ast::PolyTraitRef,
 624                             m: &'tcx ast::TraitBoundModifier) {
 625         self.smart_resolve_path(tref.trait_ref.ref_id, None,
 626                                 &tref.trait_ref.path, PathSource::Trait);
 627         visit::walk_poly_trait_ref(self, tref, m);
 628     }
 629     fn visit_variant(&mut self,
 630                      variant: &'tcx ast::Variant,
 631                      generics: &'tcx Generics,
 632                      item_id: ast::NodeId) {
 633         if let Some(ref dis_expr) = variant.node.disr_expr {
 634             // resolve the discriminator expr as a constant
 635             self.with_constant_rib(|this| {
 636                 this.visit_expr(dis_expr);
 637             });
 638         }
 639
 640         // `visit::walk_variant` without the discriminant expression.
 641         self.visit_variant_data(&variant.node.data,
 642                                 variant.node.name,
 643                                 generics,
 644                                 item_id,
 645                                 variant.span);
 646     }
 647     fn visit_foreign_item(&mut self, foreign_item: &'tcx ForeignItem) {
 648         let type_parameters = match foreign_item.node {
 649             ForeignItemKind::Fn(_, ref generics) => {
 650                 HasTypeParameters(generics, ItemRibKind)
 651             }
 652             ForeignItemKind::Static(..) => NoTypeParameters,
 653         };
 654         self.with_type_parameter_rib(type_parameters, |this| {
 655             visit::walk_foreign_item(this, foreign_item);
 656         });
 657     }
 658     fn visit_fn(&mut self,
 659                 function_kind: FnKind<'tcx>,
 660                 declaration: &'tcx FnDecl,
 661                 _: Span,
 662                 node_id: NodeId) {
 663         let rib_kind = match function_kind {
 664             FnKind::ItemFn(_, generics, ..) => {
 665                 self.visit_generics(generics);
 666                 ItemRibKind
 667             }
 668             FnKind::Method(_, sig, _, _) => {
 669                 self.visit_generics(&sig.generics);
 670                 MethodRibKind(!sig.decl.has_self())
 671             }
 672             FnKind::Closure(_) => ClosureRibKind(node_id),
 673         };
 674
 675         // Create a value rib for the function.
 676         self.ribs[ValueNS].push(Rib::new(rib_kind));
 677
 678         // Create a label rib for the function.
 679         self.label_ribs.push(Rib::new(rib_kind));
 680
 681         // Add each argument to the rib.
 682         let mut bindings_list = FxHashMap();
 683         for argument in &declaration.inputs {
 684             self.resolve_pattern(&argument.pat, PatternSource::FnParam, &mut bindings_list);
 685
 686             self.visit_ty(&argument.ty);
 687
 688             debug!("(resolving function) recorded argument");
 689         }
 690         visit::walk_fn_ret_ty(self, &declaration.output);
 691
 692         // Resolve the function body.
 693         match function_kind {
 694             FnKind::ItemFn(.., body) |
 695             FnKind::Method(.., body) => {
 696                 self.visit_block(body);
 697             }
 698             FnKind::Closure(body) => {
 699                 self.visit_expr(body);
 700             }
 701         };
 702
 703         debug!("(resolving function) leaving function");
 704
 705         self.label_ribs.pop();
 706         self.ribs[ValueNS].pop();
 707     }
 708     fn visit_generics(&mut self, generics: &'tcx Generics) {
 709         // For type parameter defaults, we have to ban access
 710         // to following type parameters, as the Substs can only
 711         // provide previous type parameters as they're built.
 712         let mut default_ban_rib = Rib::new(ForwardTyParamBanRibKind);
 713         default_ban_rib.bindings.extend(generics.ty_params.iter()
 714             .skip_while(|p| p.default.is_none())
 715             .map(|p| (Ident::with_empty_ctxt(p.ident.name), Def::Err)));
 716
 717         for param in &generics.ty_params {
 718             for bound in &param.bounds {
 719                 self.visit_ty_param_bound(bound);
 720             }
 721
 722             if let Some(ref ty) = param.default {
 723                 self.ribs[TypeNS].push(default_ban_rib);
 724                 self.visit_ty(ty);
 725                 default_ban_rib = self.ribs[TypeNS].pop().unwrap();
 726             }
 727
 728             // Allow all following defaults to refer to this type parameter.
 729             default_ban_rib.bindings.remove(&Ident::with_empty_ctxt(param.ident.name));
 730         }
 731         for lt in &generics.lifetimes { self.visit_lifetime_def(lt); }
 732         for p in &generics.where_clause.predicates { self.visit_where_predicate(p); }
 733     }
 734 }
 735
 736 pub type ErrorMessage = Option<(Span, String)>;
 737
 738 #[derive(Copy, Clone)]
 739 enum TypeParameters<'a, 'b> {
 740     NoTypeParameters,
 741     HasTypeParameters(// Type parameters.
 742                       &'b Generics,
 743
 744                       // The kind of the rib used for type parameters.
 745                       RibKind<'a>),
 746 }
 747
 748 // The rib kind controls the translation of local
 749 // definitions (`Def::Local`) to upvars (`Def::Upvar`).
 750 #[derive(Copy, Clone, Debug)]
 751 enum RibKind<'a> {
 752     // No translation needs to be applied.
 753     NormalRibKind,
 754
 755     // We passed through a closure scope at the given node ID.
 756     // Translate upvars as appropriate.
 757     ClosureRibKind(NodeId /* func id */),
 758
 759     // We passed through an impl or trait and are now in one of its
 760     // methods. Allow references to ty params that impl or trait
 761     // binds. Disallow any other upvars (including other ty params that are
 762     // upvars).
 763     //
 764     // The boolean value represents the fact that this method is static or not.
 765     MethodRibKind(bool),
 766
 767     // We passed through an item scope. Disallow upvars.
 768     ItemRibKind,
 769
 770     // We're in a constant item. Can't refer to dynamic stuff.
 771     ConstantItemRibKind,
 772
 773     // We passed through a module.
 774     ModuleRibKind(Module<'a>),
 775
 776     // We passed through a `macro_rules!` statement
 777     MacroDefinition(DefId),
 778
 779     // All bindings in this rib are type parameters that can't be used
 780     // from the default of a type parameter because they're not declared
 781     // before said type parameter. Also see the `visit_generics` override.
 782     ForwardTyParamBanRibKind,
 783 }
 784
 785 /// One local scope.
 786 #[derive(Debug)]
 787 struct Rib<'a> {
 788     bindings: FxHashMap<Ident, Def>,
 789     kind: RibKind<'a>,
 790 }
 791
 792 impl<'a> Rib<'a> {
 793     fn new(kind: RibKind<'a>) -> Rib<'a> {
 794         Rib {
 795             bindings: FxHashMap(),
 796             kind: kind,
 797         }
 798     }
 799 }
 800
 801 enum LexicalScopeBinding<'a> {
 802     Item(&'a NameBinding<'a>),
 803     Def(Def),
 804 }
 805
 806 impl<'a> LexicalScopeBinding<'a> {
 807     fn item(self) -> Option<&'a NameBinding<'a>> {
 808         match self {
 809             LexicalScopeBinding::Item(binding) => Some(binding),
 810             _ => None,
 811         }
 812     }
 813
 814     fn def(self) -> Def {
 815         match self {
 816             LexicalScopeBinding::Item(binding) => binding.def(),
 817             LexicalScopeBinding::Def(def) => def,
 818         }
 819     }
 820 }
 821
 822 #[derive(Clone)]
 823 enum PathResult<'a> {
 824     Module(Module<'a>),
 825     NonModule(PathResolution),
 826     Indeterminate,
 827     Failed(Span, String, bool /* is the error from the last segment? */),
 828 }
 829
 830 enum ModuleKind {
 831     Block(NodeId),
 832     Def(Def, Name),
 833 }
 834
 835 /// One node in the tree of modules.
 836 pub struct ModuleData<'a> {
 837     parent: Option<Module<'a>>,
 838     kind: ModuleKind,
 839
 840     // The def id of the closest normal module (`mod`) ancestor (including this module).
 841     normal_ancestor_id: DefId,
 842
 843     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
 844     legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, Span, MacroKind)>>,
 845     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 846
 847     // Macro invocations that can expand into items in this module.
 848     unresolved_invocations: RefCell<FxHashSet<Mark>>,
 849
 850     no_implicit_prelude: bool,
 851
 852     glob_importers: RefCell<Vec<&'a ImportDirective<'a>>>,
 853     globs: RefCell<Vec<&'a ImportDirective<'a>>>,
 854
 855     // Used to memoize the traits in this module for faster searches through all traits in scope.
 856     traits: RefCell<Option<Box<[(Ident, &'a NameBinding<'a>)]>>>,
 857
 858     // Whether this module is populated. If not populated, any attempt to
 859     // access the children must be preceded with a
 860     // `populate_module_if_necessary` call.
 861     populated: Cell<bool>,
 862
 863     /// Span of the module itself. Used for error reporting.
 864     span: Span,
 865
 866     expansion: Mark,
 867 }
 868
 869 pub type Module<'a> = &'a ModuleData<'a>;
 870
 871 impl<'a> ModuleData<'a> {
 872     fn new(parent: Option<Module<'a>>,
 873            kind: ModuleKind,
 874            normal_ancestor_id: DefId,
 875            expansion: Mark,
 876            span: Span) -> Self {
 877         ModuleData {
 878             parent: parent,
 879             kind: kind,
 880             normal_ancestor_id: normal_ancestor_id,
 881             resolutions: RefCell::new(FxHashMap()),
 882             legacy_macro_resolutions: RefCell::new(Vec::new()),
 883             macro_resolutions: RefCell::new(Vec::new()),
 884             unresolved_invocations: RefCell::new(FxHashSet()),
 885             no_implicit_prelude: false,
 886             glob_importers: RefCell::new(Vec::new()),
 887             globs: RefCell::new((Vec::new())),
 888             traits: RefCell::new(None),
 889             populated: Cell::new(normal_ancestor_id.is_local()),
 890             span: span,
 891             expansion: expansion,
 892         }
 893     }
 894
 895     fn for_each_child<F: FnMut(Ident, Namespace, &'a NameBinding<'a>)>(&self, mut f: F) {
 896         for (&(ident, ns), name_resolution) in self.resolutions.borrow().iter() {
 897             name_resolution.borrow().binding.map(|binding| f(ident, ns, binding));
 898         }
 899     }
 900
 901     fn def(&self) -> Option<Def> {
 902         match self.kind {
 903             ModuleKind::Def(def, _) => Some(def),
 904             _ => None,
 905         }
 906     }
 907
 908     fn def_id(&self) -> Option<DefId> {
 909         self.def().as_ref().map(Def::def_id)
 910     }
 911
 912     // `self` resolves to the first module ancestor that `is_normal`.
 913     fn is_normal(&self) -> bool {
 914         match self.kind {
 915             ModuleKind::Def(Def::Mod(_), _) => true,
 916             _ => false,
 917         }
 918     }
 919
 920     fn is_trait(&self) -> bool {
 921         match self.kind {
 922             ModuleKind::Def(Def::Trait(_), _) => true,
 923             _ => false,
 924         }
 925     }
 926
 927     fn is_local(&self) -> bool {
 928         self.normal_ancestor_id.is_local()
 929     }
 930
 931     fn nearest_item_scope(&'a self) -> Module<'a> {
 932         if self.is_trait() { self.parent.unwrap() } else { self }
 933     }
 934 }
 935
 936 impl<'a> fmt::Debug for ModuleData<'a> {
 937     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 938         write!(f, "{:?}", self.def())
 939     }
 940 }
 941
 942 // Records a possibly-private value, type, or module definition.
 943 #[derive(Clone, Debug)]
 944 pub struct NameBinding<'a> {
 945     kind: NameBindingKind<'a>,
 946     expansion: Mark,
 947     span: Span,
 948     vis: ty::Visibility,
 949 }
 950
 951 pub trait ToNameBinding<'a> {
 952     fn to_name_binding(self, arenas: &'a ResolverArenas<'a>) -> &'a NameBinding<'a>;
 953 }
 954
 955 impl<'a> ToNameBinding<'a> for &'a NameBinding<'a> {
 956     fn to_name_binding(self, _: &'a ResolverArenas<'a>) -> &'a NameBinding<'a> {
 957         self
 958     }
 959 }
 960
 961 #[derive(Clone, Debug)]
 962 enum NameBindingKind<'a> {
 963     Def(Def),
 964     Module(Module<'a>),
 965     Import {
 966         binding: &'a NameBinding<'a>,
 967         directive: &'a ImportDirective<'a>,
 968         used: Cell<bool>,
 969         legacy_self_import: bool,
 970     },
 971     Ambiguity {
 972         b1: &'a NameBinding<'a>,
 973         b2: &'a NameBinding<'a>,
 974         legacy: bool,
 975     }
 976 }
 977
 978 struct PrivacyError<'a>(Span, Name, &'a NameBinding<'a>);
 979
 980 struct AmbiguityError<'a> {
 981     span: Span,
 982     name: Name,
 983     lexical: bool,
 984     b1: &'a NameBinding<'a>,
 985     b2: &'a NameBinding<'a>,
 986     legacy: bool,
 987 }
 988
 989 impl<'a> NameBinding<'a> {
 990     fn module(&self) -> Option<Module<'a>> {
 991         match self.kind {
 992             NameBindingKind::Module(module) => Some(module),
 993             NameBindingKind::Import { binding, .. } => binding.module(),
 994             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.module(),
 995             _ => None,
 996         }
 997     }
 998
 999     fn def(&self) -> Def {
1000         match self.kind {
1001             NameBindingKind::Def(def) => def,
1002             NameBindingKind::Module(module) => module.def().unwrap(),
1003             NameBindingKind::Import { binding, .. } => binding.def(),
1004             NameBindingKind::Ambiguity { legacy: true, b1, .. } => b1.def(),
1005             NameBindingKind::Ambiguity { .. } => Def::Err,
1006         }
1007     }
1008
1009     fn def_ignoring_ambiguity(&self) -> Def {
1010         match self.kind {
1011             NameBindingKind::Import { binding, .. } => binding.def_ignoring_ambiguity(),
1012             NameBindingKind::Ambiguity { b1, .. } => b1.def_ignoring_ambiguity(),
1013             _ => self.def(),
1014         }
1015     }
1016
1017     fn get_macro(&self, resolver: &mut Resolver<'a>) -> Rc<SyntaxExtension> {
1018         resolver.get_macro(self.def_ignoring_ambiguity())
1019     }
1020
1021     // We sometimes need to treat variants as `pub` for backwards compatibility
1022     fn pseudo_vis(&self) -> ty::Visibility {
1023         if self.is_variant() { ty::Visibility::Public } else { self.vis }
1024     }
1025
1026     fn is_variant(&self) -> bool {
1027         match self.kind {
1028             NameBindingKind::Def(Def::Variant(..)) |
1029             NameBindingKind::Def(Def::VariantCtor(..)) => true,
1030             _ => false,
1031         }
1032     }
1033
1034     fn is_extern_crate(&self) -> bool {
1035         match self.kind {
1036             NameBindingKind::Import {
1037                 directive: &ImportDirective {
1038                     subclass: ImportDirectiveSubclass::ExternCrate, ..
1039                 }, ..
1040             } => true,
1041             _ => false,
1042         }
1043     }
1044
1045     fn is_import(&self) -> bool {
1046         match self.kind {
1047             NameBindingKind::Import { .. } => true,
1048             _ => false,
1049         }
1050     }
1051
1052     fn is_glob_import(&self) -> bool {
1053         match self.kind {
1054             NameBindingKind::Import { directive, .. } => directive.is_glob(),
1055             NameBindingKind::Ambiguity { b1, .. } => b1.is_glob_import(),
1056             _ => false,
1057         }
1058     }
1059
1060     fn is_importable(&self) -> bool {
1061         match self.def() {
1062             Def::AssociatedConst(..) | Def::Method(..) | Def::AssociatedTy(..) => false,
1063             _ => true,
1064         }
1065     }
1066
1067     fn is_macro_def(&self) -> bool {
1068         match self.kind {
1069             NameBindingKind::Def(Def::Macro(..)) => true,
1070             _ => false,
1071         }
1072     }
1073
1074     fn descr(&self) -> &'static str {
1075         if self.is_extern_crate() { "extern crate" } else { self.def().kind_name() }
1076     }
1077 }
1078
1079 /// Interns the names of the primitive types.
1080 struct PrimitiveTypeTable {
1081     primitive_types: FxHashMap<Name, PrimTy>,
1082 }
1083
1084 impl PrimitiveTypeTable {
1085     fn new() -> PrimitiveTypeTable {
1086         let mut table = PrimitiveTypeTable { primitive_types: FxHashMap() };
1087
1088         table.intern("bool", TyBool);
1089         table.intern("char", TyChar);
1090         table.intern("f32", TyFloat(FloatTy::F32));
1091         table.intern("f64", TyFloat(FloatTy::F64));
1092         table.intern("isize", TyInt(IntTy::Is));
1093         table.intern("i8", TyInt(IntTy::I8));
1094         table.intern("i16", TyInt(IntTy::I16));
1095         table.intern("i32", TyInt(IntTy::I32));
1096         table.intern("i64", TyInt(IntTy::I64));
1097         table.intern("i128", TyInt(IntTy::I128));
1098         table.intern("str", TyStr);
1099         table.intern("usize", TyUint(UintTy::Us));
1100         table.intern("u8", TyUint(UintTy::U8));
1101         table.intern("u16", TyUint(UintTy::U16));
1102         table.intern("u32", TyUint(UintTy::U32));
1103         table.intern("u64", TyUint(UintTy::U64));
1104         table.intern("u128", TyUint(UintTy::U128));
1105         table
1106     }
1107
1108     fn intern(&mut self, string: &str, primitive_type: PrimTy) {
1109         self.primitive_types.insert(Symbol::intern(string), primitive_type);
1110     }
1111 }
1112
1113 /// The main resolver class.
1114 pub struct Resolver<'a> {
1115     session: &'a Session,
1116
1117     pub definitions: Definitions,
1118
1119     graph_root: Module<'a>,
1120
1121     prelude: Option<Module<'a>>,
1122
1123     // n.b. This is used only for better diagnostics, not name resolution itself.
1124     has_self: FxHashSet<DefId>,
1125
1126     // Names of fields of an item `DefId` accessible with dot syntax.
1127     // Used for hints during error reporting.
1128     field_names: FxHashMap<DefId, Vec<Name>>,
1129
1130     // All imports known to succeed or fail.
1131     determined_imports: Vec<&'a ImportDirective<'a>>,
1132
1133     // All non-determined imports.
1134     indeterminate_imports: Vec<&'a ImportDirective<'a>>,
1135
1136     // The module that represents the current item scope.
1137     current_module: Module<'a>,
1138
1139     // The current set of local scopes for types and values.
1140     // FIXME #4948: Reuse ribs to avoid allocation.
1141     ribs: PerNS<Vec<Rib<'a>>>,
1142
1143     // The current set of local scopes, for labels.
1144     label_ribs: Vec<Rib<'a>>,
1145
1146     // The trait that the current context can refer to.
1147     current_trait_ref: Option<(Module<'a>, TraitRef)>,
1148
1149     // The current self type if inside an impl (used for better errors).
1150     current_self_type: Option<Ty>,
1151
1152     // The idents for the primitive types.
1153     primitive_type_table: PrimitiveTypeTable,
1154
1155     def_map: DefMap,
1156     pub freevars: FreevarMap,
1157     freevars_seen: NodeMap<NodeMap<usize>>,
1158     pub export_map: ExportMap,
1159     pub trait_map: TraitMap,
1160
1161     // A map from nodes to anonymous modules.
1162     // Anonymous modules are pseudo-modules that are implicitly created around items
1163     // contained within blocks.
1164     //
1165     // For example, if we have this:
1166     //
1167     //  fn f() {
1168     //      fn g() {
1169     //          ...
1170     //      }
1171     //  }
1172     //
1173     // There will be an anonymous module created around `g` with the ID of the
1174     // entry block for `f`.
1175     block_map: NodeMap<Module<'a>>,
1176     module_map: FxHashMap<DefId, Module<'a>>,
1177     extern_module_map: FxHashMap<(DefId, bool /* MacrosOnly? */), Module<'a>>,
1178
1179     pub make_glob_map: bool,
1180     // Maps imports to the names of items actually imported (this actually maps
1181     // all imports, but only glob imports are actually interesting).
1182     pub glob_map: GlobMap,
1183
1184     used_imports: FxHashSet<(NodeId, Namespace)>,
1185     pub maybe_unused_trait_imports: NodeSet,
1186
1187     privacy_errors: Vec<PrivacyError<'a>>,
1188     ambiguity_errors: Vec<AmbiguityError<'a>>,
1189     gated_errors: FxHashSet<Span>,
1190     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
1191
1192     arenas: &'a ResolverArenas<'a>,
1193     dummy_binding: &'a NameBinding<'a>,
1194     use_extern_macros: bool, // true if `#![feature(use_extern_macros)]`
1195
1196     crate_loader: &'a mut CrateLoader,
1197     macro_names: FxHashSet<Ident>,
1198     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
1199     lexical_macro_resolutions: Vec<(Ident, &'a Cell<LegacyScope<'a>>)>,
1200     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
1201     macro_defs: FxHashMap<Mark, DefId>,
1202     local_macro_def_scopes: FxHashMap<NodeId, Module<'a>>,
1203     macro_exports: Vec<Export>,
1204     pub whitelisted_legacy_custom_derives: Vec<Name>,
1205     pub found_unresolved_macro: bool,
1206
1207     // List of crate local macros that we need to warn about as being unused.
1208     // Right now this only includes macro_rules! macros, and macros 2.0.
1209     unused_macros: FxHashSet<DefId>,
1210
1211     // Maps the `Mark` of an expansion to its containing module or block.
1212     invocations: FxHashMap<Mark, &'a InvocationData<'a>>,
1213
1214     // Avoid duplicated errors for "name already defined".
1215     name_already_seen: FxHashMap<Name, Span>,
1216
1217     // If `#![feature(proc_macro)]` is set
1218     proc_macro_enabled: bool,
1219
1220     // A set of procedural macros imported by `#[macro_use]` that have already been warned about
1221     warned_proc_macros: FxHashSet<Name>,
1222
1223     potentially_unused_imports: Vec<&'a ImportDirective<'a>>,
1224
1225     // This table maps struct IDs into struct constructor IDs,
1226     // it's not used during normal resolution, only for better error reporting.
1227     struct_constructors: DefIdMap<(Def, ty::Visibility)>,
1228
1229     // Only used for better errors on `fn(): fn()`
1230     current_type_ascription: Vec<Span>,
1231 }
1232
1233 pub struct ResolverArenas<'a> {
1234     modules: arena::TypedArena<ModuleData<'a>>,
1235     local_modules: RefCell<Vec<Module<'a>>>,
1236     name_bindings: arena::TypedArena<NameBinding<'a>>,
1237     import_directives: arena::TypedArena<ImportDirective<'a>>,
1238     name_resolutions: arena::TypedArena<RefCell<NameResolution<'a>>>,
1239     invocation_data: arena::TypedArena<InvocationData<'a>>,
1240     legacy_bindings: arena::TypedArena<LegacyBinding<'a>>,
1241 }
1242
1243 impl<'a> ResolverArenas<'a> {
1244     fn alloc_module(&'a self, module: ModuleData<'a>) -> Module<'a> {
1245         let module = self.modules.alloc(module);
1246         if module.def_id().map(|def_id| def_id.is_local()).unwrap_or(true) {
1247             self.local_modules.borrow_mut().push(module);
1248         }
1249         module
1250     }
1251     fn local_modules(&'a self) -> ::std::cell::Ref<'a, Vec<Module<'a>>> {
1252         self.local_modules.borrow()
1253     }
1254     fn alloc_name_binding(&'a self, name_binding: NameBinding<'a>) -> &'a NameBinding<'a> {
1255         self.name_bindings.alloc(name_binding)
1256     }
1257     fn alloc_import_directive(&'a self, import_directive: ImportDirective<'a>)
1258                               -> &'a ImportDirective {
1259         self.import_directives.alloc(import_directive)
1260     }
1261     fn alloc_name_resolution(&'a self) -> &'a RefCell<NameResolution<'a>> {
1262         self.name_resolutions.alloc(Default::default())
1263     }
1264     fn alloc_invocation_data(&'a self, expansion_data: InvocationData<'a>)
1265                              -> &'a InvocationData<'a> {
1266         self.invocation_data.alloc(expansion_data)
1267     }
1268     fn alloc_legacy_binding(&'a self, binding: LegacyBinding<'a>) -> &'a LegacyBinding<'a> {
1269         self.legacy_bindings.alloc(binding)
1270     }
1271 }
1272
1273 impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
1274     fn parent(self, id: DefId) -> Option<DefId> {
1275         match id.krate {
1276             LOCAL_CRATE => self.definitions.def_key(id.index).parent,
1277             _ => self.session.cstore.def_key(id).parent,
1278         }.map(|index| DefId { index: index, ..id })
1279     }
1280 }
1281
1282 impl<'a> hir::lowering::Resolver for Resolver<'a> {
1283     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
1284         let namespace = if is_value { ValueNS } else { TypeNS };
1285         let hir::Path { ref segments, span, ref mut def } = *path;
1286         let path: Vec<SpannedIdent> = segments.iter()
1287             .map(|seg| respan(span, Ident::with_empty_ctxt(seg.name)))
1288             .collect();
1289         match self.resolve_path(&path, Some(namespace), true, span) {
1290             PathResult::Module(module) => *def = module.def().unwrap(),
1291             PathResult::NonModule(path_res) if path_res.unresolved_segments() == 0 =>
1292                 *def = path_res.base_def(),
1293             PathResult::NonModule(..) => match self.resolve_path(&path, None, true, span) {
1294                 PathResult::Failed(span, msg, _) => {
1295                     resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1296                 }
1297                 _ => {}
1298             },
1299             PathResult::Indeterminate => unreachable!(),
1300             PathResult::Failed(span, msg, _) => {
1301                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
1302             }
1303         }
1304     }
1305
1306     fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
1307         self.def_map.get(&id).cloned()
1308     }
1309
1310     fn definitions(&mut self) -> &mut Definitions {
1311         &mut self.definitions
1312     }
1313 }
1314
1315 impl<'a> Resolver<'a> {
1316     pub fn new(session: &'a Session,
1317                krate: &Crate,
1318                crate_name: &str,
1319                make_glob_map: MakeGlobMap,
1320                crate_loader: &'a mut CrateLoader,
1321                arenas: &'a ResolverArenas<'a>)
1322                -> Resolver<'a> {
1323         let root_def_id = DefId::local(CRATE_DEF_INDEX);
1324         let root_module_kind = ModuleKind::Def(Def::Mod(root_def_id), keywords::Invalid.name());
1325         let graph_root = arenas.alloc_module(ModuleData {
1326             no_implicit_prelude: attr::contains_name(&krate.attrs, "no_implicit_prelude"),
1327             ..ModuleData::new(None, root_module_kind, root_def_id, Mark::root(), krate.span)
1328         });
1329         let mut module_map = FxHashMap();
1330         module_map.insert(DefId::local(CRATE_DEF_INDEX), graph_root);
1331
1332         let mut definitions = Definitions::new();
1333         DefCollector::new(&mut definitions, Mark::root())
1334             .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
1335
1336         let mut invocations = FxHashMap();
1337         invocations.insert(Mark::root(),
1338                            arenas.alloc_invocation_data(InvocationData::root(graph_root)));
1339
1340         let features = session.features.borrow();
1341
1342         let mut macro_defs = FxHashMap();
1343         macro_defs.insert(Mark::root(), root_def_id);
1344
1345         Resolver {
1346             session: session,
1347
1348             definitions: definitions,
1349
1350             // The outermost module has def ID 0; this is not reflected in the
1351             // AST.
1352             graph_root: graph_root,
1353             prelude: None,
1354
1355             has_self: FxHashSet(),
1356             field_names: FxHashMap(),
1357
1358             determined_imports: Vec::new(),
1359             indeterminate_imports: Vec::new(),
1360
1361             current_module: graph_root,
1362             ribs: PerNS {
1363                 value_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1364                 type_ns: vec![Rib::new(ModuleRibKind(graph_root))],
1365                 macro_ns: Some(vec![Rib::new(ModuleRibKind(graph_root))]),
1366             },
1367             label_ribs: Vec::new(),
1368
1369             current_trait_ref: None,
1370             current_self_type: None,
1371
1372             primitive_type_table: PrimitiveTypeTable::new(),
1373
1374             def_map: NodeMap(),
1375             freevars: NodeMap(),
1376             freevars_seen: NodeMap(),
1377             export_map: NodeMap(),
1378             trait_map: NodeMap(),
1379             module_map: module_map,
1380             block_map: NodeMap(),
1381             extern_module_map: FxHashMap(),
1382
1383             make_glob_map: make_glob_map == MakeGlobMap::Yes,
1384             glob_map: NodeMap(),
1385
1386             used_imports: FxHashSet(),
1387             maybe_unused_trait_imports: NodeSet(),
1388
1389             privacy_errors: Vec::new(),
1390             ambiguity_errors: Vec::new(),
1391             gated_errors: FxHashSet(),
1392             disallowed_shadowing: Vec::new(),
1393
1394             arenas: arenas,
1395             dummy_binding: arenas.alloc_name_binding(NameBinding {
1396                 kind: NameBindingKind::Def(Def::Err),
1397                 expansion: Mark::root(),
1398                 span: DUMMY_SP,
1399                 vis: ty::Visibility::Public,
1400             }),
1401
1402             // The `proc_macro` and `decl_macro` features imply `use_extern_macros`
1403             use_extern_macros:
1404                 features.use_extern_macros || features.proc_macro || features.decl_macro,
1405
1406             crate_loader: crate_loader,
1407             macro_names: FxHashSet(),
1408             global_macros: FxHashMap(),
1409             lexical_macro_resolutions: Vec::new(),
1410             macro_map: FxHashMap(),
1411             macro_exports: Vec::new(),
1412             invocations: invocations,
1413             macro_defs: macro_defs,
1414             local_macro_def_scopes: FxHashMap(),
1415             name_already_seen: FxHashMap(),
1416             whitelisted_legacy_custom_derives: Vec::new(),
1417             proc_macro_enabled: features.proc_macro,
1418             warned_proc_macros: FxHashSet(),
1419             potentially_unused_imports: Vec::new(),
1420             struct_constructors: DefIdMap(),
1421             found_unresolved_macro: false,
1422             unused_macros: FxHashSet(),
1423             current_type_ascription: Vec::new(),
1424         }
1425     }
1426
1427     pub fn arenas() -> ResolverArenas<'a> {
1428         ResolverArenas {
1429             modules: arena::TypedArena::new(),
1430             local_modules: RefCell::new(Vec::new()),
1431             name_bindings: arena::TypedArena::new(),
1432             import_directives: arena::TypedArena::new(),
1433             name_resolutions: arena::TypedArena::new(),
1434             invocation_data: arena::TypedArena::new(),
1435             legacy_bindings: arena::TypedArena::new(),
1436         }
1437     }
1438
1439     fn per_ns<T, F: FnMut(&mut Self, Namespace) -> T>(&mut self, mut f: F) -> PerNS<T> {
1440         PerNS {
1441             type_ns: f(self, TypeNS),
1442             value_ns: f(self, ValueNS),
1443             macro_ns: match self.use_extern_macros {
1444                 true => Some(f(self, MacroNS)),
1445                 false => None,
1446             },
1447         }
1448     }
1449
1450     /// Entry point to crate resolution.
1451     pub fn resolve_crate(&mut self, krate: &Crate) {
1452         ImportResolver { resolver: self }.finalize_imports();
1453         self.current_module = self.graph_root;
1454         self.finalize_current_module_macro_resolutions();
1455         visit::walk_crate(self, krate);
1456
1457         check_unused::check_crate(self, krate);
1458         self.report_errors();
1459         self.crate_loader.postprocess(krate);
1460     }
1461
1462     fn new_module(
1463         &self,
1464         parent: Module<'a>,
1465         kind: ModuleKind,
1466         normal_ancestor_id: DefId,
1467         expansion: Mark,
1468         span: Span,
1469     ) -> Module<'a> {
1470         let module = ModuleData::new(Some(parent), kind, normal_ancestor_id, expansion, span);
1471         self.arenas.alloc_module(module)
1472     }
1473
1474     fn record_use(&mut self, ident: Ident, ns: Namespace, binding: &'a NameBinding<'a>, span: Span)
1475                   -> bool /* true if an error was reported */ {
1476         match binding.kind {
1477             NameBindingKind::Import { directive, binding, ref used, legacy_self_import }
1478                     if !used.get() => {
1479                 used.set(true);
1480                 directive.used.set(true);
1481                 if legacy_self_import {
1482                     self.warn_legacy_self_import(directive);
1483                     return false;
1484                 }
1485                 self.used_imports.insert((directive.id, ns));
1486                 self.add_to_glob_map(directive.id, ident);
1487                 self.record_use(ident, ns, binding, span)
1488             }
1489             NameBindingKind::Import { .. } => false,
1490             NameBindingKind::Ambiguity { b1, b2, legacy } => {
1491                 self.ambiguity_errors.push(AmbiguityError {
1492                     span: span, name: ident.name, lexical: false, b1: b1, b2: b2, legacy: legacy,
1493                 });
1494                 if legacy {
1495                     self.record_use(ident, ns, b1, span);
1496                 }
1497                 !legacy
1498             }
1499             _ => false
1500         }
1501     }
1502
1503     fn add_to_glob_map(&mut self, id: NodeId, ident: Ident) {
1504         if self.make_glob_map {
1505             self.glob_map.entry(id).or_insert_with(FxHashSet).insert(ident.name);
1506         }
1507     }
1508
1509     /// This resolves the identifier `ident` in the namespace `ns` in the current lexical scope.
1510     /// More specifically, we proceed up the hierarchy of scopes and return the binding for
1511     /// `ident` in the first scope that defines it (or None if no scopes define it).
1512     ///
1513     /// A block's items are above its local variables in the scope hierarchy, regardless of where
1514     /// the items are defined in the block. For example,
1515     /// ```rust
1516     /// fn f() {
1517     ///    g(); // Since there are no local variables in scope yet, this resolves to the item.
1518     ///    let g = || {};
1519     ///    fn g() {}
1520     ///    g(); // This resolves to the local variable `g` since it shadows the item.
1521     /// }
1522     /// ```
1523     ///
1524     /// Invariant: This must only be called during main resolution, not during
1525     /// import resolution.
1526     fn resolve_ident_in_lexical_scope(&mut self,
1527                                       mut ident: Ident,
1528                                       ns: Namespace,
1529                                       record_used: bool,
1530                                       path_span: Span)
1531                                       -> Option<LexicalScopeBinding<'a>> {
1532         if ns == TypeNS {
1533             ident.ctxt = if ident.name == keywords::SelfType.name() {
1534                 SyntaxContext::empty() // FIXME(jseyfried) improve `Self` hygiene
1535             } else {
1536                 ident.ctxt.modern()
1537             }
1538         }
1539
1540         // Walk backwards up the ribs in scope.
1541         let mut module = self.graph_root;
1542         for i in (0 .. self.ribs[ns].len()).rev() {
1543             if let Some(def) = self.ribs[ns][i].bindings.get(&ident).cloned() {
1544                 // The ident resolves to a type parameter or local variable.
1545                 return Some(LexicalScopeBinding::Def(
1546                     self.adjust_local_def(ns, i, def, record_used, path_span)
1547                 ));
1548             }
1549
1550             module = match self.ribs[ns][i].kind {
1551                 ModuleRibKind(module) => module,
1552                 MacroDefinition(def) if def == self.macro_defs[&ident.ctxt.outer()] => {
1553                     // If an invocation of this macro created `ident`, give up on `ident`
1554                     // and switch to `ident`'s source from the macro definition.
1555                     ident.ctxt.remove_mark();
1556                     continue
1557                 }
1558                 _ => continue,
1559             };
1560
1561             let item = self.resolve_ident_in_module_unadjusted(
1562                 module, ident, ns, false, record_used, path_span,
1563             );
1564             if let Ok(binding) = item {
1565                 // The ident resolves to an item.
1566                 return Some(LexicalScopeBinding::Item(binding));
1567             }
1568
1569             match module.kind {
1570                 ModuleKind::Block(..) => {}, // We can see through blocks
1571                 _ => break,
1572             }
1573         }
1574
1575         ident.ctxt = ident.ctxt.modern();
1576         loop {
1577             module = unwrap_or!(self.hygienic_lexical_parent(module, &mut ident.ctxt), break);
1578             let orig_current_module = self.current_module;
1579             self.current_module = module; // Lexical resolutions can never be a privacy error.
1580             let result = self.resolve_ident_in_module_unadjusted(
1581                 module, ident, ns, false, record_used, path_span,
1582             );
1583             self.current_module = orig_current_module;
1584
1585             match result {
1586                 Ok(binding) => return Some(LexicalScopeBinding::Item(binding)),
1587                 Err(Undetermined) => return None,
1588                 Err(Determined) => {}
1589             }
1590         }
1591
1592         match self.prelude {
1593             Some(prelude) if !module.no_implicit_prelude => {
1594                 self.resolve_ident_in_module_unadjusted(prelude, ident, ns, false, false, path_span)
1595                     .ok().map(LexicalScopeBinding::Item)
1596             }
1597             _ => None,
1598         }
1599     }
1600
1601     fn hygienic_lexical_parent(&mut self, mut module: Module<'a>, ctxt: &mut SyntaxContext)
1602                                -> Option<Module<'a>> {
1603         if !module.expansion.is_descendant_of(ctxt.outer()) {
1604             return Some(self.macro_def_scope(ctxt.remove_mark()));
1605         }
1606
1607         if let ModuleKind::Block(..) = module.kind {
1608             return Some(module.parent.unwrap());
1609         }
1610
1611         let mut module_expansion = module.expansion.modern(); // for backward compatability
1612         while let Some(parent) = module.parent {
1613             let parent_expansion = parent.expansion.modern();
1614             if module_expansion.is_descendant_of(parent_expansion) &&
1615                parent_expansion != module_expansion {
1616                 return if parent_expansion.is_descendant_of(ctxt.outer()) {
1617                     Some(parent)
1618                 } else {
1619                     None
1620                 };
1621             }
1622             module = parent;
1623             module_expansion = parent_expansion;
1624         }
1625
1626         None
1627     }
1628
1629     fn resolve_ident_in_module(&mut self,
1630                                module: Module<'a>,
1631                                mut ident: Ident,
1632                                ns: Namespace,
1633                                ignore_unresolved_invocations: bool,
1634                                record_used: bool,
1635                                span: Span)
1636                                -> Result<&'a NameBinding<'a>, Determinacy> {
1637         ident.ctxt = ident.ctxt.modern();
1638         let orig_current_module = self.current_module;
1639         if let Some(def) = ident.ctxt.adjust(module.expansion) {
1640             self.current_module = self.macro_def_scope(def);
1641         }
1642         let result = self.resolve_ident_in_module_unadjusted(
1643             module, ident, ns, ignore_unresolved_invocations, record_used, span,
1644         );
1645         self.current_module = orig_current_module;
1646         result
1647     }
1648
1649     fn resolve_crate_root(&mut self, mut ctxt: SyntaxContext) -> Module<'a> {
1650         let module = match ctxt.adjust(Mark::root()) {
1651             Some(def) => self.macro_def_scope(def),
1652             None => return self.graph_root,
1653         };
1654         self.get_module(DefId { index: CRATE_DEF_INDEX, ..module.normal_ancestor_id })
1655     }
1656
1657     fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
1658         let mut module = self.get_module(module.normal_ancestor_id);
1659         while module.span.ctxt.modern() != *ctxt {
1660             let parent = module.parent.unwrap_or_else(|| self.macro_def_scope(ctxt.remove_mark()));
1661             module = self.get_module(parent.normal_ancestor_id);
1662         }
1663         module
1664     }
1665
1666     // AST resolution
1667     //
1668     // We maintain a list of value ribs and type ribs.
1669     //
1670     // Simultaneously, we keep track of the current position in the module
1671     // graph in the `current_module` pointer. When we go to resolve a name in
1672     // the value or type namespaces, we first look through all the ribs and
1673     // then query the module graph. When we resolve a name in the module
1674     // namespace, we can skip all the ribs (since nested modules are not
1675     // allowed within blocks in Rust) and jump straight to the current module
1676     // graph node.
1677     //
1678     // Named implementations are handled separately. When we find a method
1679     // call, we consult the module node to find all of the implementations in
1680     // scope. This information is lazily cached in the module node. We then
1681     // generate a fake "implementation scope" containing all the
1682     // implementations thus found, for compatibility with old resolve pass.
1683
1684     fn with_scope<F>(&mut self, id: NodeId, f: F)
1685         where F: FnOnce(&mut Resolver)
1686     {
1687         let id = self.definitions.local_def_id(id);
1688         let module = self.module_map.get(&id).cloned(); // clones a reference
1689         if let Some(module) = module {
1690             // Move down in the graph.
1691             let orig_module = replace(&mut self.current_module, module);
1692             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
1693             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
1694
1695             self.finalize_current_module_macro_resolutions();
1696             f(self);
1697
1698             self.current_module = orig_module;
1699             self.ribs[ValueNS].pop();
1700             self.ribs[TypeNS].pop();
1701         } else {
1702             f(self);
1703         }
1704     }
1705
1706     /// Searches the current set of local scopes for labels.
1707     /// Stops after meeting a closure.
1708     fn search_label(&self, mut ident: Ident) -> Option<Def> {
1709         for rib in self.label_ribs.iter().rev() {
1710             match rib.kind {
1711                 NormalRibKind => {}
1712                 // If an invocation of this macro created `ident`, give up on `ident`
1713                 // and switch to `ident`'s source from the macro definition.
1714                 MacroDefinition(def) => {
1715                     if def == self.macro_defs[&ident.ctxt.outer()] {
1716                         ident.ctxt.remove_mark();
1717                     }
1718                 }
1719                 _ => {
1720                     // Do not resolve labels across function boundary
1721                     return None;
1722                 }
1723             }
1724             let result = rib.bindings.get(&ident).cloned();
1725             if result.is_some() {
1726                 return result;
1727             }
1728         }
1729         None
1730     }
1731
1732     fn resolve_item(&mut self, item: &Item) {
1733         let name = item.ident.name;
1734
1735         debug!("(resolving item) resolving {}", name);
1736
1737         self.check_proc_macro_attrs(&item.attrs);
1738
1739         match item.node {
1740             ItemKind::Enum(_, ref generics) |
1741             ItemKind::Ty(_, ref generics) |
1742             ItemKind::Struct(_, ref generics) |
1743             ItemKind::Union(_, ref generics) |
1744             ItemKind::Fn(.., ref generics, _) => {
1745                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind),
1746                                              |this| visit::walk_item(this, item));
1747             }
1748
1749             ItemKind::DefaultImpl(_, ref trait_ref) => {
1750                 self.with_optional_trait_ref(Some(trait_ref), |this, _| {
1751                     // Resolve type arguments in trait path
1752                     visit::walk_trait_ref(this, trait_ref);
1753                 });
1754             }
1755             ItemKind::Impl(.., ref generics, ref opt_trait_ref, ref self_type, ref impl_items) =>
1756                 self.resolve_implementation(generics,
1757                                             opt_trait_ref,
1758                                             &self_type,
1759                                             item.id,
1760                                             impl_items),
1761
1762             ItemKind::Trait(_, ref generics, ref bounds, ref trait_items) => {
1763                 // Create a new rib for the trait-wide type parameters.
1764                 self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1765                     let local_def_id = this.definitions.local_def_id(item.id);
1766                     this.with_self_rib(Def::SelfTy(Some(local_def_id), None), |this| {
1767                         this.visit_generics(generics);
1768                         walk_list!(this, visit_ty_param_bound, bounds);
1769
1770                         for trait_item in trait_items {
1771                             this.check_proc_macro_attrs(&trait_item.attrs);
1772
1773                             match trait_item.node {
1774                                 TraitItemKind::Const(ref ty, ref default) => {
1775                                     this.visit_ty(ty);
1776
1777                                     // Only impose the restrictions of
1778                                     // ConstRibKind for an actual constant
1779                                     // expression in a provided default.
1780                                     if let Some(ref expr) = *default{
1781                                         this.with_constant_rib(|this| {
1782                                             this.visit_expr(expr);
1783                                         });
1784                                     }
1785                                 }
1786                                 TraitItemKind::Method(ref sig, _) => {
1787                                     let type_parameters =
1788                                         HasTypeParameters(&sig.generics,
1789                                                           MethodRibKind(!sig.decl.has_self()));
1790                                     this.with_type_parameter_rib(type_parameters, |this| {
1791                                         visit::walk_trait_item(this, trait_item)
1792                                     });
1793                                 }
1794                                 TraitItemKind::Type(..) => {
1795                                     this.with_type_parameter_rib(NoTypeParameters, |this| {
1796                                         visit::walk_trait_item(this, trait_item)
1797                                     });
1798                                 }
1799                                 TraitItemKind::Macro(_) => panic!("unexpanded macro in resolve!"),
1800                             };
1801                         }
1802                     });
1803                 });
1804             }
1805
1806             ItemKind::Mod(_) | ItemKind::ForeignMod(_) => {
1807                 self.with_scope(item.id, |this| {
1808                     visit::walk_item(this, item);
1809                 });
1810             }
1811
1812             ItemKind::Static(ref ty, _, ref expr) |
1813             ItemKind::Const(ref ty, ref expr) => {
1814                 self.with_item_rib(|this| {
1815                     this.visit_ty(ty);
1816                     this.with_constant_rib(|this| {
1817                         this.visit_expr(expr);
1818                     });
1819                 });
1820             }
1821
1822             ItemKind::Use(ref view_path) => {
1823                 match view_path.node {
1824                     ast::ViewPathList(ref prefix, ref items) if items.is_empty() => {
1825                         // Resolve prefix of an import with empty braces (issue #28388).
1826                         self.smart_resolve_path(item.id, None, prefix, PathSource::ImportPrefix);
1827                     }
1828                     _ => {}
1829                 }
1830             }
1831
1832             ItemKind::ExternCrate(_) | ItemKind::MacroDef(..) | ItemKind::GlobalAsm(_)=> {
1833                 // do nothing, these are just around to be encoded
1834             }
1835
1836             ItemKind::Mac(_) => panic!("unexpanded macro in resolve!"),
1837         }
1838     }
1839
1840     fn with_type_parameter_rib<'b, F>(&'b mut self, type_parameters: TypeParameters<'a, 'b>, f: F)
1841         where F: FnOnce(&mut Resolver)
1842     {
1843         match type_parameters {
1844             HasTypeParameters(generics, rib_kind) => {
1845                 let mut function_type_rib = Rib::new(rib_kind);
1846                 let mut seen_bindings = FxHashMap();
1847                 for type_parameter in &generics.ty_params {
1848                     let ident = type_parameter.ident.modern();
1849                     debug!("with_type_parameter_rib: {}", type_parameter.id);
1850
1851                     if seen_bindings.contains_key(&ident) {
1852                         let span = seen_bindings.get(&ident).unwrap();
1853                         let err =
1854                             ResolutionError::NameAlreadyUsedInTypeParameterList(ident.name, span);
1855                         resolve_error(self, type_parameter.span, err);
1856                     }
1857                     seen_bindings.entry(ident).or_insert(type_parameter.span);
1858
1859                     // plain insert (no renaming)
1860                     let def_id = self.definitions.local_def_id(type_parameter.id);
1861                     let def = Def::TyParam(def_id);
1862                     function_type_rib.bindings.insert(ident, def);
1863                     self.record_def(type_parameter.id, PathResolution::new(def));
1864                 }
1865                 self.ribs[TypeNS].push(function_type_rib);
1866             }
1867
1868             NoTypeParameters => {
1869                 // Nothing to do.
1870             }
1871         }
1872
1873         f(self);
1874
1875         if let HasTypeParameters(..) = type_parameters {
1876             self.ribs[TypeNS].pop();
1877         }
1878     }
1879
1880     fn with_label_rib<F>(&mut self, f: F)
1881         where F: FnOnce(&mut Resolver)
1882     {
1883         self.label_ribs.push(Rib::new(NormalRibKind));
1884         f(self);
1885         self.label_ribs.pop();
1886     }
1887
1888     fn with_item_rib<F>(&mut self, f: F)
1889         where F: FnOnce(&mut Resolver)
1890     {
1891         self.ribs[ValueNS].push(Rib::new(ItemRibKind));
1892         self.ribs[TypeNS].push(Rib::new(ItemRibKind));
1893         f(self);
1894         self.ribs[TypeNS].pop();
1895         self.ribs[ValueNS].pop();
1896     }
1897
1898     fn with_constant_rib<F>(&mut self, f: F)
1899         where F: FnOnce(&mut Resolver)
1900     {
1901         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
1902         f(self);
1903         self.ribs[ValueNS].pop();
1904     }
1905
1906     fn with_current_self_type<T, F>(&mut self, self_type: &Ty, f: F) -> T
1907         where F: FnOnce(&mut Resolver) -> T
1908     {
1909         // Handle nested impls (inside fn bodies)
1910         let previous_value = replace(&mut self.current_self_type, Some(self_type.clone()));
1911         let result = f(self);
1912         self.current_self_type = previous_value;
1913         result
1914     }
1915
1916     fn with_optional_trait_ref<T, F>(&mut self, opt_trait_ref: Option<&TraitRef>, f: F) -> T
1917         where F: FnOnce(&mut Resolver, Option<DefId>) -> T
1918     {
1919         let mut new_val = None;
1920         let mut new_id = None;
1921         if let Some(trait_ref) = opt_trait_ref {
1922             let path: Vec<_> = trait_ref.path.segments.iter()
1923                 .map(|seg| respan(seg.span, seg.identifier))
1924                 .collect();
1925             let def = self.smart_resolve_path_fragment(trait_ref.ref_id,
1926                                                        None,
1927                                                        &path,
1928                                                        trait_ref.path.span,
1929                                                        trait_ref.path.segments.last().unwrap().span,
1930                                                        PathSource::Trait)
1931                 .base_def();
1932             if def != Def::Err {
1933                 new_id = Some(def.def_id());
1934                 let span = trait_ref.path.span;
1935                 if let PathResult::Module(module) = self.resolve_path(&path, None, false, span) {
1936                     new_val = Some((module, trait_ref.clone()));
1937                 }
1938             }
1939         }
1940         let original_trait_ref = replace(&mut self.current_trait_ref, new_val);
1941         let result = f(self, new_id);
1942         self.current_trait_ref = original_trait_ref;
1943         result
1944     }
1945
1946     fn with_self_rib<F>(&mut self, self_def: Def, f: F)
1947         where F: FnOnce(&mut Resolver)
1948     {
1949         let mut self_type_rib = Rib::new(NormalRibKind);
1950
1951         // plain insert (no renaming, types are not currently hygienic....)
1952         self_type_rib.bindings.insert(keywords::SelfType.ident(), self_def);
1953         self.ribs[TypeNS].push(self_type_rib);
1954         f(self);
1955         self.ribs[TypeNS].pop();
1956     }
1957
1958     fn resolve_implementation(&mut self,
1959                               generics: &Generics,
1960                               opt_trait_reference: &Option<TraitRef>,
1961                               self_type: &Ty,
1962                               item_id: NodeId,
1963                               impl_items: &[ImplItem]) {
1964         // If applicable, create a rib for the type parameters.
1965         self.with_type_parameter_rib(HasTypeParameters(generics, ItemRibKind), |this| {
1966             // Dummy self type for better errors if `Self` is used in the trait path.
1967             this.with_self_rib(Def::SelfTy(None, None), |this| {
1968                 // Resolve the trait reference, if necessary.
1969                 this.with_optional_trait_ref(opt_trait_reference.as_ref(), |this, trait_id| {
1970                     let item_def_id = this.definitions.local_def_id(item_id);
1971                     this.with_self_rib(Def::SelfTy(trait_id, Some(item_def_id)), |this| {
1972                         if let Some(trait_ref) = opt_trait_reference.as_ref() {
1973                             // Resolve type arguments in trait path
1974                             visit::walk_trait_ref(this, trait_ref);
1975                         }
1976                         // Resolve the self type.
1977                         this.visit_ty(self_type);
1978                         // Resolve the type parameters.
1979                         this.visit_generics(generics);
1980                         this.with_current_self_type(self_type, |this| {
1981                             for impl_item in impl_items {
1982                                 this.check_proc_macro_attrs(&impl_item.attrs);
1983                                 this.resolve_visibility(&impl_item.vis);
1984                                 match impl_item.node {
1985                                     ImplItemKind::Const(..) => {
1986                                         // If this is a trait impl, ensure the const
1987                                         // exists in trait
1988                                         this.check_trait_item(impl_item.ident,
1989                                                             ValueNS,
1990                                                             impl_item.span,
1991                                             |n, s| ResolutionError::ConstNotMemberOfTrait(n, s));
1992                                         visit::walk_impl_item(this, impl_item);
1993                                     }
1994                                     ImplItemKind::Method(ref sig, _) => {
1995                                         // If this is a trait impl, ensure the method
1996                                         // exists in trait
1997                                         this.check_trait_item(impl_item.ident,
1998                                                             ValueNS,
1999                                                             impl_item.span,
2000                                             |n, s| ResolutionError::MethodNotMemberOfTrait(n, s));
2001
2002                                         // We also need a new scope for the method-
2003                                         // specific type parameters.
2004                                         let type_parameters =
2005                                             HasTypeParameters(&sig.generics,
2006                                                             MethodRibKind(!sig.decl.has_self()));
2007                                         this.with_type_parameter_rib(type_parameters, |this| {
2008                                             visit::walk_impl_item(this, impl_item);
2009                                         });
2010                                     }
2011                                     ImplItemKind::Type(ref ty) => {
2012                                         // If this is a trait impl, ensure the type
2013                                         // exists in trait
2014                                         this.check_trait_item(impl_item.ident,
2015                                                             TypeNS,
2016                                                             impl_item.span,
2017                                             |n, s| ResolutionError::TypeNotMemberOfTrait(n, s));
2018
2019                                         this.visit_ty(ty);
2020                                     }
2021                                     ImplItemKind::Macro(_) =>
2022                                         panic!("unexpanded macro in resolve!"),
2023                                 }
2024                             }
2025                         });
2026                     });
2027                 });
2028             });
2029         });
2030     }
2031
2032     fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
2033         where F: FnOnce(Name, &str) -> ResolutionError
2034     {
2035         // If there is a TraitRef in scope for an impl, then the method must be in the
2036         // trait.
2037         if let Some((module, _)) = self.current_trait_ref {
2038             if self.resolve_ident_in_module(module, ident, ns, false, false, span).is_err() {
2039                 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
2040                 resolve_error(self, span, err(ident.name, &path_names_to_string(path)));
2041             }
2042         }
2043     }
2044
2045     fn resolve_local(&mut self, local: &Local) {
2046         // Resolve the type.
2047         walk_list!(self, visit_ty, &local.ty);
2048
2049         // Resolve the initializer.
2050         walk_list!(self, visit_expr, &local.init);
2051
2052         // Resolve the pattern.
2053         self.resolve_pattern(&local.pat, PatternSource::Let, &mut FxHashMap());
2054     }
2055
2056     // build a map from pattern identifiers to binding-info's.
2057     // this is done hygienically. This could arise for a macro
2058     // that expands into an or-pattern where one 'x' was from the
2059     // user and one 'x' came from the macro.
2060     fn binding_mode_map(&mut self, pat: &Pat) -> BindingMap {
2061         let mut binding_map = FxHashMap();
2062
2063         pat.walk(&mut |pat| {
2064             if let PatKind::Ident(binding_mode, ident, ref sub_pat) = pat.node {
2065                 if sub_pat.is_some() || match self.def_map.get(&pat.id).map(|res| res.base_def()) {
2066                     Some(Def::Local(..)) => true,
2067                     _ => false,
2068                 } {
2069                     let binding_info = BindingInfo { span: ident.span, binding_mode: binding_mode };
2070                     binding_map.insert(ident.node, binding_info);
2071                 }
2072             }
2073             true
2074         });
2075
2076         binding_map
2077     }
2078
2079     // check that all of the arms in an or-pattern have exactly the
2080     // same set of bindings, with the same binding modes for each.
2081     fn check_consistent_bindings(&mut self, arm: &Arm) {
2082         if arm.pats.is_empty() {
2083             return;
2084         }
2085
2086         let mut missing_vars = FxHashMap();
2087         let mut inconsistent_vars = FxHashMap();
2088         for (i, p) in arm.pats.iter().enumerate() {
2089             let map_i = self.binding_mode_map(&p);
2090
2091             for (j, q) in arm.pats.iter().enumerate() {
2092                 if i == j {
2093                     continue;
2094                 }
2095
2096                 let map_j = self.binding_mode_map(&q);
2097                 for (&key, &binding_i) in &map_i {
2098                     if map_j.len() == 0 {                   // Account for missing bindings when
2099                         let binding_error = missing_vars    // map_j has none.
2100                             .entry(key.name)
2101                             .or_insert(BindingError {
2102                                 name: key.name,
2103                                 origin: BTreeSet::new(),
2104                                 target: BTreeSet::new(),
2105                             });
2106                         binding_error.origin.insert(binding_i.span);
2107                         binding_error.target.insert(q.span);
2108                     }
2109                     for (&key_j, &binding_j) in &map_j {
2110                         match map_i.get(&key_j) {
2111                             None => {  // missing binding
2112                                 let binding_error = missing_vars
2113                                     .entry(key_j.name)
2114                                     .or_insert(BindingError {
2115                                         name: key_j.name,
2116                                         origin: BTreeSet::new(),
2117                                         target: BTreeSet::new(),
2118                                     });
2119                                 binding_error.origin.insert(binding_j.span);
2120                                 binding_error.target.insert(p.span);
2121                             }
2122                             Some(binding_i) => {  // check consistent binding
2123                                 if binding_i.binding_mode != binding_j.binding_mode {
2124                                     inconsistent_vars
2125                                         .entry(key.name)
2126                                         .or_insert((binding_j.span, binding_i.span));
2127                                 }
2128                             }
2129                         }
2130                     }
2131                 }
2132             }
2133         }
2134         let mut missing_vars = missing_vars.iter().collect::<Vec<_>>();
2135         missing_vars.sort();
2136         for (_, v) in missing_vars {
2137             resolve_error(self,
2138                           *v.origin.iter().next().unwrap(),
2139                           ResolutionError::VariableNotBoundInPattern(v));
2140         }
2141         let mut inconsistent_vars = inconsistent_vars.iter().collect::<Vec<_>>();
2142         inconsistent_vars.sort();
2143         for (name, v) in inconsistent_vars {
2144             resolve_error(self, v.0, ResolutionError::VariableBoundWithDifferentMode(*name, v.1));
2145         }
2146     }
2147
2148     fn resolve_arm(&mut self, arm: &Arm) {
2149         self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2150
2151         let mut bindings_list = FxHashMap();
2152         for pattern in &arm.pats {
2153             self.resolve_pattern(&pattern, PatternSource::Match, &mut bindings_list);
2154         }
2155
2156         // This has to happen *after* we determine which
2157         // pat_idents are variants
2158         self.check_consistent_bindings(arm);
2159
2160         walk_list!(self, visit_expr, &arm.guard);
2161         self.visit_expr(&arm.body);
2162
2163         self.ribs[ValueNS].pop();
2164     }
2165
2166     fn resolve_block(&mut self, block: &Block) {
2167         debug!("(resolving block) entering block");
2168         // Move down in the graph, if there's an anonymous module rooted here.
2169         let orig_module = self.current_module;
2170         let anonymous_module = self.block_map.get(&block.id).cloned(); // clones a reference
2171
2172         let mut num_macro_definition_ribs = 0;
2173         if let Some(anonymous_module) = anonymous_module {
2174             debug!("(resolving block) found anonymous module, moving down");
2175             self.ribs[ValueNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2176             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(anonymous_module)));
2177             self.current_module = anonymous_module;
2178             self.finalize_current_module_macro_resolutions();
2179         } else {
2180             self.ribs[ValueNS].push(Rib::new(NormalRibKind));
2181         }
2182
2183         // Descend into the block.
2184         for stmt in &block.stmts {
2185             if let ast::StmtKind::Item(ref item) = stmt.node {
2186                 if let ast::ItemKind::MacroDef(..) = item.node {
2187                     num_macro_definition_ribs += 1;
2188                     let def = self.definitions.local_def_id(item.id);
2189                     self.ribs[ValueNS].push(Rib::new(MacroDefinition(def)));
2190                     self.label_ribs.push(Rib::new(MacroDefinition(def)));
2191                 }
2192             }
2193
2194             self.visit_stmt(stmt);
2195         }
2196
2197         // Move back up.
2198         self.current_module = orig_module;
2199         for _ in 0 .. num_macro_definition_ribs {
2200             self.ribs[ValueNS].pop();
2201             self.label_ribs.pop();
2202         }
2203         self.ribs[ValueNS].pop();
2204         if let Some(_) = anonymous_module {
2205             self.ribs[TypeNS].pop();
2206         }
2207         debug!("(resolving block) leaving block");
2208     }
2209
2210     fn fresh_binding(&mut self,
2211                      ident: &SpannedIdent,
2212                      pat_id: NodeId,
2213                      outer_pat_id: NodeId,
2214                      pat_src: PatternSource,
2215                      bindings: &mut FxHashMap<Ident, NodeId>)
2216                      -> PathResolution {
2217         // Add the binding to the local ribs, if it
2218         // doesn't already exist in the bindings map. (We
2219         // must not add it if it's in the bindings map
2220         // because that breaks the assumptions later
2221         // passes make about or-patterns.)
2222         let mut def = Def::Local(self.definitions.local_def_id(pat_id));
2223         match bindings.get(&ident.node).cloned() {
2224             Some(id) if id == outer_pat_id => {
2225                 // `Variant(a, a)`, error
2226                 resolve_error(
2227                     self,
2228                     ident.span,
2229                     ResolutionError::IdentifierBoundMoreThanOnceInSamePattern(
2230                         &ident.node.name.as_str())
2231                 );
2232             }
2233             Some(..) if pat_src == PatternSource::FnParam => {
2234                 // `fn f(a: u8, a: u8)`, error
2235                 resolve_error(
2236                     self,
2237                     ident.span,
2238                     ResolutionError::IdentifierBoundMoreThanOnceInParameterList(
2239                         &ident.node.name.as_str())
2240                 );
2241             }
2242             Some(..) if pat_src == PatternSource::Match => {
2243                 // `Variant1(a) | Variant2(a)`, ok
2244                 // Reuse definition from the first `a`.
2245                 def = self.ribs[ValueNS].last_mut().unwrap().bindings[&ident.node];
2246             }
2247             Some(..) => {
2248                 span_bug!(ident.span, "two bindings with the same name from \
2249                                        unexpected pattern source {:?}", pat_src);
2250             }
2251             None => {
2252                 // A completely fresh binding, add to the lists if it's valid.
2253                 if ident.node.name != keywords::Invalid.name() {
2254                     bindings.insert(ident.node, outer_pat_id);
2255                     self.ribs[ValueNS].last_mut().unwrap().bindings.insert(ident.node, def);
2256                 }
2257             }
2258         }
2259
2260         PathResolution::new(def)
2261     }
2262
2263     fn resolve_pattern(&mut self,
2264                        pat: &Pat,
2265                        pat_src: PatternSource,
2266                        // Maps idents to the node ID for the
2267                        // outermost pattern that binds them.
2268                        bindings: &mut FxHashMap<Ident, NodeId>) {
2269         // Visit all direct subpatterns of this pattern.
2270         let outer_pat_id = pat.id;
2271         pat.walk(&mut |pat| {
2272             match pat.node {
2273                 PatKind::Ident(bmode, ref ident, ref opt_pat) => {
2274                     // First try to resolve the identifier as some existing
2275                     // entity, then fall back to a fresh binding.
2276                     let binding = self.resolve_ident_in_lexical_scope(ident.node, ValueNS,
2277                                                                       false, pat.span)
2278                                       .and_then(LexicalScopeBinding::item);
2279                     let resolution = binding.map(NameBinding::def).and_then(|def| {
2280                         let ivmode = BindingMode::ByValue(Mutability::Immutable);
2281                         let always_binding = !pat_src.is_refutable() || opt_pat.is_some() ||
2282                                              bmode != ivmode;
2283                         match def {
2284                             Def::StructCtor(_, CtorKind::Const) |
2285                             Def::VariantCtor(_, CtorKind::Const) |
2286                             Def::Const(..) if !always_binding => {
2287                                 // A unit struct/variant or constant pattern.
2288                                 self.record_use(ident.node, ValueNS, binding.unwrap(), ident.span);
2289                                 Some(PathResolution::new(def))
2290                             }
2291                             Def::StructCtor(..) | Def::VariantCtor(..) |
2292                             Def::Const(..) | Def::Static(..) => {
2293                                 // A fresh binding that shadows something unacceptable.
2294                                 resolve_error(
2295                                     self,
2296                                     ident.span,
2297                                     ResolutionError::BindingShadowsSomethingUnacceptable(
2298                                         pat_src.descr(), ident.node.name, binding.unwrap())
2299                                 );
2300                                 None
2301                             }
2302                             Def::Local(..) | Def::Upvar(..) | Def::Fn(..) | Def::Err => {
2303                                 // These entities are explicitly allowed
2304                                 // to be shadowed by fresh bindings.
2305                                 None
2306                             }
2307                             def => {
2308                                 span_bug!(ident.span, "unexpected definition for an \
2309                                                        identifier in pattern: {:?}", def);
2310                             }
2311                         }
2312                     }).unwrap_or_else(|| {
2313                         self.fresh_binding(ident, pat.id, outer_pat_id, pat_src, bindings)
2314                     });
2315
2316                     self.record_def(pat.id, resolution);
2317                 }
2318
2319                 PatKind::TupleStruct(ref path, ..) => {
2320                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);
2321                 }
2322
2323                 PatKind::Path(ref qself, ref path) => {
2324                     self.smart_resolve_path(pat.id, qself.as_ref(), path, PathSource::Pat);
2325                 }
2326
2327                 PatKind::Struct(ref path, ..) => {
2328                     self.smart_resolve_path(pat.id, None, path, PathSource::Struct);
2329                 }
2330
2331                 _ => {}
2332             }
2333             true
2334         });
2335
2336         visit::walk_pat(self, pat);
2337     }
2338
2339     // High-level and context dependent path resolution routine.
2340     // Resolves the path and records the resolution into definition map.
2341     // If resolution fails tries several techniques to find likely
2342     // resolution candidates, suggest imports or other help, and report
2343     // errors in user friendly way.
2344     fn smart_resolve_path(&mut self,
2345                           id: NodeId,
2346                           qself: Option<&QSelf>,
2347                           path: &Path,
2348                           source: PathSource)
2349                           -> PathResolution {
2350         let segments = &path.segments.iter()
2351             .map(|seg| respan(seg.span, seg.identifier))
2352             .collect::<Vec<_>>();
2353         let ident_span = path.segments.last().map_or(path.span, |seg| seg.span);
2354         self.smart_resolve_path_fragment(id, qself, segments, path.span, ident_span, source)
2355     }
2356
2357     fn smart_resolve_path_fragment(&mut self,
2358                                    id: NodeId,
2359                                    qself: Option<&QSelf>,
2360                                    path: &[SpannedIdent],
2361                                    span: Span,
2362                                    ident_span: Span,
2363                                    source: PathSource)
2364                                    -> PathResolution {
2365         let ns = source.namespace();
2366         let is_expected = &|def| source.is_expected(def);
2367         let is_enum_variant = &|def| if let Def::Variant(..) = def { true } else { false };
2368
2369         // Base error is amended with one short label and possibly some longer helps/notes.
2370         let report_errors = |this: &mut Self, def: Option<Def>| {
2371             // Make the base error.
2372             let expected = source.descr_expected();
2373             let path_str = names_to_string(path);
2374             let code = source.error_code(def.is_some());
2375             let (base_msg, fallback_label, base_span) = if let Some(def) = def {
2376                 (format!("expected {}, found {} `{}`", expected, def.kind_name(), path_str),
2377                  format!("not a {}", expected), span)
2378             } else {
2379                 let item_str = path[path.len() - 1].node;
2380                 let item_span = path[path.len() - 1].span;
2381                 let (mod_prefix, mod_str) = if path.len() == 1 {
2382                     (format!(""), format!("this scope"))
2383                 } else if path.len() == 2 && path[0].node.name == keywords::CrateRoot.name() {
2384                     (format!(""), format!("the crate root"))
2385                 } else {
2386                     let mod_path = &path[..path.len() - 1];
2387                     let mod_prefix = match this.resolve_path(mod_path, Some(TypeNS), false, span) {
2388                         PathResult::Module(module) => module.def(),
2389                         _ => None,
2390                     }.map_or(format!(""), |def| format!("{} ", def.kind_name()));
2391                     (mod_prefix, format!("`{}`", names_to_string(mod_path)))
2392                 };
2393                 (format!("cannot find {} `{}` in {}{}", expected, item_str, mod_prefix, mod_str),
2394                  format!("not found in {}", mod_str), item_span)
2395             };
2396             let mut err = this.session.struct_span_err_with_code(base_span, &base_msg, code);
2397
2398             // Emit special messages for unresolved `Self` and `self`.
2399             if is_self_type(path, ns) {
2400                 __diagnostic_used!(E0411);
2401                 err.code("E0411".into());
2402                 err.span_label(span, "`Self` is only available in traits and impls");
2403                 return err;
2404             }
2405             if is_self_value(path, ns) {
2406                 __diagnostic_used!(E0424);
2407                 err.code("E0424".into());
2408                 err.span_label(span, format!("`self` value is only available in \
2409                                                methods with `self` parameter"));
2410                 return err;
2411             }
2412
2413             // Try to lookup the name in more relaxed fashion for better error reporting.
2414             let ident = *path.last().unwrap();
2415             let candidates = this.lookup_import_candidates(ident.node.name, ns, is_expected);
2416             if !candidates.is_empty() {
2417                 let mut module_span = this.current_module.span;
2418                 module_span.hi = module_span.lo;
2419                 // Report import candidates as help and proceed searching for labels.
2420                 show_candidates(&mut err, module_span, &candidates, def.is_some());
2421             } else if is_expected(Def::Enum(DefId::local(CRATE_DEF_INDEX))) {
2422                 let enum_candidates =
2423                     this.lookup_import_candidates(ident.node.name, ns, is_enum_variant);
2424                 let mut enum_candidates = enum_candidates.iter()
2425                     .map(|suggestion| import_candidate_to_paths(&suggestion)).collect::<Vec<_>>();
2426                 enum_candidates.sort();
2427                 for (sp, variant_path, enum_path) in enum_candidates {
2428                     if sp == DUMMY_SP {
2429                         let msg = format!("there is an enum variant `{}`, \
2430                                         try using `{}`?",
2431                                         variant_path,
2432                                         enum_path);
2433                         err.help(&msg);
2434                     } else {
2435                         err.span_suggestion(span, "you can try using the variant's enum",
2436                                             enum_path);
2437                     }
2438                 }
2439             }
2440             if path.len() == 1 && this.self_type_is_available(span) {
2441                 if let Some(candidate) = this.lookup_assoc_candidate(ident.node, ns, is_expected) {
2442                     let self_is_available = this.self_value_is_available(path[0].node.ctxt, span);
2443                     match candidate {
2444                         AssocSuggestion::Field => {
2445                             err.span_suggestion(span, "try",
2446                                                 format!("self.{}", path_str));
2447                             if !self_is_available {
2448                                 err.span_label(span, format!("`self` value is only available in \
2449                                                                methods with `self` parameter"));
2450                             }
2451                         }
2452                         AssocSuggestion::MethodWithSelf if self_is_available => {
2453                             err.span_suggestion(span, "try",
2454                                                 format!("self.{}", path_str));
2455                         }
2456                         AssocSuggestion::MethodWithSelf | AssocSuggestion::AssocItem => {
2457                             err.span_suggestion(span, "try",
2458                                                 format!("Self::{}", path_str));
2459                         }
2460                     }
2461                     return err;
2462                 }
2463             }
2464
2465             let mut levenshtein_worked = false;
2466
2467             // Try Levenshtein.
2468             if let Some(candidate) = this.lookup_typo_candidate(path, ns, is_expected, span) {
2469                 err.span_label(ident_span, format!("did you mean `{}`?", candidate));
2470                 levenshtein_worked = true;
2471             }
2472
2473             // Try context dependent help if relaxed lookup didn't work.
2474             if let Some(def) = def {
2475                 match (def, source) {
2476                     (Def::Macro(..), _) => {
2477                         err.span_label(span, format!("did you mean `{}!(...)`?", path_str));
2478                         return err;
2479                     }
2480                     (Def::TyAlias(..), PathSource::Trait) => {
2481                         err.span_label(span, "type aliases cannot be used for traits");
2482                         return err;
2483                     }
2484                     (Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
2485                         ExprKind::Field(_, ident) => {
2486                             err.span_label(parent.span, format!("did you mean `{}::{}`?",
2487                                                                  path_str, ident.node));
2488                             return err;
2489                         }
2490                         ExprKind::MethodCall(ref segment, ..) => {
2491                             err.span_label(parent.span, format!("did you mean `{}::{}(...)`?",
2492                                                                  path_str, segment.identifier));
2493                             return err;
2494                         }
2495                         _ => {}
2496                     },
2497                     _ if ns == ValueNS && is_struct_like(def) => {
2498                         if let Def::Struct(def_id) = def {
2499                             if let Some((ctor_def, ctor_vis))
2500                                     = this.struct_constructors.get(&def_id).cloned() {
2501                                 if is_expected(ctor_def) && !this.is_accessible(ctor_vis) {
2502                                     err.span_label(span, format!("constructor is not visible \
2503                                                                    here due to private fields"));
2504                                 }
2505                             }
2506                         }
2507                         err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?",
2508                                                        path_str));
2509                         return err;
2510                     }
2511                     _ => {}
2512                 }
2513             }
2514
2515             // Fallback label.
2516             if !levenshtein_worked {
2517                 err.span_label(base_span, fallback_label);
2518                 this.type_ascription_suggestion(&mut err, base_span);
2519             }
2520             err
2521         };
2522         let report_errors = |this: &mut Self, def: Option<Def>| {
2523             report_errors(this, def).emit();
2524             err_path_resolution()
2525         };
2526
2527         let resolution = match self.resolve_qpath_anywhere(id, qself, path, ns, span,
2528                                                            source.defer_to_typeck(),
2529                                                            source.global_by_default()) {
2530             Some(resolution) if resolution.unresolved_segments() == 0 => {
2531                 if is_expected(resolution.base_def()) || resolution.base_def() == Def::Err {
2532                     resolution
2533                 } else {
2534                     // Add a temporary hack to smooth the transition to new struct ctor
2535                     // visibility rules. See #38932 for more details.
2536                     let mut res = None;
2537                     if let Def::Struct(def_id) = resolution.base_def() {
2538                         if let Some((ctor_def, ctor_vis))
2539                                 = self.struct_constructors.get(&def_id).cloned() {
2540                             if is_expected(ctor_def) && self.is_accessible(ctor_vis) {
2541                                 let lint = lint::builtin::LEGACY_CONSTRUCTOR_VISIBILITY;
2542                                 self.session.add_lint(lint, id, span,
2543                                     "private struct constructors are not usable through \
2544                                      reexports in outer modules".to_string());
2545                                 res = Some(PathResolution::new(ctor_def));
2546                             }
2547                         }
2548                     }
2549
2550                     res.unwrap_or_else(|| report_errors(self, Some(resolution.base_def())))
2551                 }
2552             }
2553             Some(resolution) if source.defer_to_typeck() => {
2554                 // Not fully resolved associated item `T::A::B` or `<T as Tr>::A::B`
2555                 // or `<T>::A::B`. If `B` should be resolved in value namespace then
2556                 // it needs to be added to the trait map.
2557                 if ns == ValueNS {
2558                     let item_name = path.last().unwrap().node;
2559                     let traits = self.get_traits_containing_item(item_name, ns);
2560                     self.trait_map.insert(id, traits);
2561                 }
2562                 resolution
2563             }
2564             _ => report_errors(self, None)
2565         };
2566
2567         if let PathSource::TraitItem(..) = source {} else {
2568             // Avoid recording definition of `A::B` in `<T as A>::B::C`.
2569             self.record_def(id, resolution);
2570         }
2571         resolution
2572     }
2573
2574     fn type_ascription_suggestion(&self,
2575                                   err: &mut DiagnosticBuilder,
2576                                   base_span: Span) {
2577         debug!("type_ascription_suggetion {:?}", base_span);
2578         let cm = self.session.codemap();
2579         debug!("self.current_type_ascription {:?}", self.current_type_ascription);
2580         if let Some(sp) = self.current_type_ascription.last() {
2581             let mut sp = *sp;
2582             loop {  // try to find the `:`, bail on first non-':'/non-whitespace
2583                 sp = sp.next_point();
2584                 if let Ok(snippet) = cm.span_to_snippet(sp.to(sp.next_point())) {
2585                     debug!("snippet {:?}", snippet);
2586                     let line_sp = cm.lookup_char_pos(sp.hi).line;
2587                     let line_base_sp = cm.lookup_char_pos(base_span.lo).line;
2588                     debug!("{:?} {:?}", line_sp, line_base_sp);
2589                     if snippet == ":" {
2590                         err.span_label(base_span,
2591                                        "expecting a type here because of type ascription");
2592                         if line_sp != line_base_sp {
2593                             err.span_suggestion_short(sp,
2594                                                       "did you mean to use `;` here instead?",
2595                                                       ";".to_string());
2596                         }
2597                         break;
2598                     } else if snippet.trim().len() != 0  {
2599                         debug!("tried to find type ascription `:` token, couldn't find it");
2600                         break;
2601                     }
2602                 } else {
2603                     break;
2604                 }
2605             }
2606         }
2607     }
2608
2609     fn self_type_is_available(&mut self, span: Span) -> bool {
2610         let binding = self.resolve_ident_in_lexical_scope(keywords::SelfType.ident(),
2611                                                           TypeNS, false, span);
2612         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2613     }
2614
2615     fn self_value_is_available(&mut self, ctxt: SyntaxContext, span: Span) -> bool {
2616         let ident = Ident { name: keywords::SelfValue.name(), ctxt: ctxt };
2617         let binding = self.resolve_ident_in_lexical_scope(ident, ValueNS, false, span);
2618         if let Some(LexicalScopeBinding::Def(def)) = binding { def != Def::Err } else { false }
2619     }
2620
2621     // Resolve in alternative namespaces if resolution in the primary namespace fails.
2622     fn resolve_qpath_anywhere(&mut self,
2623                               id: NodeId,
2624                               qself: Option<&QSelf>,
2625                               path: &[SpannedIdent],
2626                               primary_ns: Namespace,
2627                               span: Span,
2628                               defer_to_typeck: bool,
2629                               global_by_default: bool)
2630                               -> Option<PathResolution> {
2631         let mut fin_res = None;
2632         // FIXME: can't resolve paths in macro namespace yet, macros are
2633         // processed by the little special hack below.
2634         for (i, ns) in [primary_ns, TypeNS, ValueNS, /*MacroNS*/].iter().cloned().enumerate() {
2635             if i == 0 || ns != primary_ns {
2636                 match self.resolve_qpath(id, qself, path, ns, span, global_by_default) {
2637                     // If defer_to_typeck, then resolution > no resolution,
2638                     // otherwise full resolution > partial resolution > no resolution.
2639                     Some(res) if res.unresolved_segments() == 0 || defer_to_typeck =>
2640                         return Some(res),
2641                     res => if fin_res.is_none() { fin_res = res },
2642                 };
2643             }
2644         }
2645         let is_global = self.global_macros.get(&path[0].node.name).cloned()
2646             .map(|binding| binding.get_macro(self).kind() == MacroKind::Bang).unwrap_or(false);
2647         if primary_ns != MacroNS && (is_global ||
2648                                      self.macro_names.contains(&path[0].node.modern())) {
2649             // Return some dummy definition, it's enough for error reporting.
2650             return Some(
2651                 PathResolution::new(Def::Macro(DefId::local(CRATE_DEF_INDEX), MacroKind::Bang))
2652             );
2653         }
2654         fin_res
2655     }
2656
2657     /// Handles paths that may refer to associated items.
2658     fn resolve_qpath(&mut self,
2659                      id: NodeId,
2660                      qself: Option<&QSelf>,
2661                      path: &[SpannedIdent],
2662                      ns: Namespace,
2663                      span: Span,
2664                      global_by_default: bool)
2665                      -> Option<PathResolution> {
2666         if let Some(qself) = qself {
2667             if qself.position == 0 {
2668                 // FIXME: Create some fake resolution that can't possibly be a type.
2669                 return Some(PathResolution::with_unresolved_segments(
2670                     Def::Mod(DefId::local(CRATE_DEF_INDEX)), path.len()
2671                 ));
2672             }
2673             // Make sure `A::B` in `<T as A>::B::C` is a trait item.
2674             let ns = if qself.position + 1 == path.len() { ns } else { TypeNS };
2675             let res = self.smart_resolve_path_fragment(id, None, &path[..qself.position + 1],
2676                                                        span, span, PathSource::TraitItem(ns));
2677             return Some(PathResolution::with_unresolved_segments(
2678                 res.base_def(), res.unresolved_segments() + path.len() - qself.position - 1
2679             ));
2680         }
2681
2682         let result = match self.resolve_path(&path, Some(ns), true, span) {
2683             PathResult::NonModule(path_res) => path_res,
2684             PathResult::Module(module) if !module.is_normal() => {
2685                 PathResolution::new(module.def().unwrap())
2686             }
2687             // In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
2688             // don't report an error right away, but try to fallback to a primitive type.
2689             // So, we are still able to successfully resolve something like
2690             //
2691             // use std::u8; // bring module u8 in scope
2692             // fn f() -> u8 { // OK, resolves to primitive u8, not to std::u8
2693             //     u8::max_value() // OK, resolves to associated function <u8>::max_value,
2694             //                     // not to non-existent std::u8::max_value
2695             // }
2696             //
2697             // Such behavior is required for backward compatibility.
2698             // The same fallback is used when `a` resolves to nothing.
2699             PathResult::Module(..) | PathResult::Failed(..)
2700                     if (ns == TypeNS || path.len() > 1) &&
2701                        self.primitive_type_table.primitive_types
2702                            .contains_key(&path[0].node.name) => {
2703                 let prim = self.primitive_type_table.primitive_types[&path[0].node.name];
2704                 match prim {
2705                     TyUint(UintTy::U128) | TyInt(IntTy::I128) => {
2706                         if !self.session.features.borrow().i128_type {
2707                             emit_feature_err(&self.session.parse_sess,
2708                                                 "i128_type", span, GateIssue::Language,
2709                                                 "128-bit type is unstable");
2710
2711                         }
2712                     }
2713                     _ => {}
2714                 }
2715                 PathResolution::with_unresolved_segments(Def::PrimTy(prim), path.len() - 1)
2716             }
2717             PathResult::Module(module) => PathResolution::new(module.def().unwrap()),
2718             PathResult::Failed(span, msg, false) => {
2719                 resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
2720                 err_path_resolution()
2721             }
2722             PathResult::Failed(..) => return None,
2723             PathResult::Indeterminate => bug!("indetermined path result in resolve_qpath"),
2724         };
2725
2726         if path.len() > 1 && !global_by_default && result.base_def() != Def::Err &&
2727            path[0].node.name != keywords::CrateRoot.name() &&
2728            path[0].node.name != keywords::DollarCrate.name() {
2729             let unqualified_result = {
2730                 match self.resolve_path(&[*path.last().unwrap()], Some(ns), false, span) {
2731                     PathResult::NonModule(path_res) => path_res.base_def(),
2732                     PathResult::Module(module) => module.def().unwrap(),
2733                     _ => return Some(result),
2734                 }
2735             };
2736             if result.base_def() == unqualified_result {
2737                 let lint = lint::builtin::UNUSED_QUALIFICATIONS;
2738                 self.session.add_lint(lint, id, span, "unnecessary qualification".to_string());
2739             }
2740         }
2741
2742         Some(result)
2743     }
2744
2745     fn resolve_path(&mut self,
2746                     path: &[SpannedIdent],
2747                     opt_ns: Option<Namespace>, // `None` indicates a module path
2748                     record_used: bool,
2749                     path_span: Span)
2750                     -> PathResult<'a> {
2751         let mut module = None;
2752         let mut allow_super = true;
2753
2754         for (i, &ident) in path.iter().enumerate() {
2755             debug!("resolve_path ident {} {:?}", i, ident);
2756             let is_last = i == path.len() - 1;
2757             let ns = if is_last { opt_ns.unwrap_or(TypeNS) } else { TypeNS };
2758
2759             if i == 0 && ns == TypeNS && ident.node.name == keywords::SelfValue.name() {
2760                 let mut ctxt = ident.node.ctxt.modern();
2761                 module = Some(self.resolve_self(&mut ctxt, self.current_module));
2762                 continue
2763             } else if allow_super && ns == TypeNS && ident.node.name == keywords::Super.name() {
2764                 let mut ctxt = ident.node.ctxt.modern();
2765                 let self_module = match i {
2766                     0 => self.resolve_self(&mut ctxt, self.current_module),
2767                     _ => module.unwrap(),
2768                 };
2769                 if let Some(parent) = self_module.parent {
2770                     module = Some(self.resolve_self(&mut ctxt, parent));
2771                     continue
2772                 } else {
2773                     let msg = "There are too many initial `super`s.".to_string();
2774                     return PathResult::Failed(ident.span, msg, false);
2775                 }
2776             }
2777             allow_super = false;
2778
2779             if i == 0 && ns == TypeNS && ident.node.name == keywords::CrateRoot.name() {
2780                 module = Some(self.resolve_crate_root(ident.node.ctxt.modern()));
2781                 continue
2782             } else if i == 0 && ns == TypeNS && ident.node.name == keywords::DollarCrate.name() {
2783                 module = Some(self.resolve_crate_root(ident.node.ctxt));
2784                 continue
2785             }
2786
2787             let binding = if let Some(module) = module {
2788                 self.resolve_ident_in_module(module, ident.node, ns, false, record_used, path_span)
2789             } else if opt_ns == Some(MacroNS) {
2790                 self.resolve_lexical_macro_path_segment(ident.node, ns, record_used, path_span)
2791                     .map(MacroBinding::binding)
2792             } else {
2793                 match self.resolve_ident_in_lexical_scope(ident.node, ns, record_used, path_span) {
2794                     Some(LexicalScopeBinding::Item(binding)) => Ok(binding),
2795                     Some(LexicalScopeBinding::Def(def))
2796                             if opt_ns == Some(TypeNS) || opt_ns == Some(ValueNS) => {
2797                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2798                             def, path.len() - 1
2799                         ));
2800                     }
2801                     _ => Err(if record_used { Determined } else { Undetermined }),
2802                 }
2803             };
2804
2805             match binding {
2806                 Ok(binding) => {
2807                     let def = binding.def();
2808                     let maybe_assoc = opt_ns != Some(MacroNS) && PathSource::Type.is_expected(def);
2809                     if let Some(next_module) = binding.module() {
2810                         module = Some(next_module);
2811                     } else if def == Def::Err {
2812                         return PathResult::NonModule(err_path_resolution());
2813                     } else if opt_ns.is_some() && (is_last || maybe_assoc) {
2814                         return PathResult::NonModule(PathResolution::with_unresolved_segments(
2815                             def, path.len() - i - 1
2816                         ));
2817                     } else {
2818                         return PathResult::Failed(ident.span,
2819                                                   format!("Not a module `{}`", ident.node),
2820                                                   is_last);
2821                     }
2822                 }
2823                 Err(Undetermined) => return PathResult::Indeterminate,
2824                 Err(Determined) => {
2825                     if let Some(module) = module {
2826                         if opt_ns.is_some() && !module.is_normal() {
2827                             return PathResult::NonModule(PathResolution::with_unresolved_segments(
2828                                 module.def().unwrap(), path.len() - i
2829                             ));
2830                         }
2831                     }
2832                     let msg = if module.and_then(ModuleData::def) == self.graph_root.def() {
2833                         let is_mod = |def| match def { Def::Mod(..) => true, _ => false };
2834                         let mut candidates =
2835                             self.lookup_import_candidates(ident.node.name, TypeNS, is_mod);
2836                         candidates.sort_by_key(|c| (c.path.segments.len(), c.path.to_string()));
2837                         if let Some(candidate) = candidates.get(0) {
2838                             format!("Did you mean `{}`?", candidate.path)
2839                         } else {
2840                             format!("Maybe a missing `extern crate {};`?", ident.node)
2841                         }
2842                     } else if i == 0 {
2843                         format!("Use of undeclared type or module `{}`", ident.node)
2844                     } else {
2845                         format!("Could not find `{}` in `{}`", ident.node, path[i - 1].node)
2846                     };
2847                     return PathResult::Failed(ident.span, msg, is_last);
2848                 }
2849             }
2850         }
2851
2852         PathResult::Module(module.unwrap_or(self.graph_root))
2853     }
2854
2855     // Resolve a local definition, potentially adjusting for closures.
2856     fn adjust_local_def(&mut self,
2857                         ns: Namespace,
2858                         rib_index: usize,
2859                         mut def: Def,
2860                         record_used: bool,
2861                         span: Span) -> Def {
2862         let ribs = &self.ribs[ns][rib_index + 1..];
2863
2864         // An invalid forward use of a type parameter from a previous default.
2865         if let ForwardTyParamBanRibKind = self.ribs[ns][rib_index].kind {
2866             if record_used {
2867                 resolve_error(self, span, ResolutionError::ForwardDeclaredTyParam);
2868             }
2869             assert_eq!(def, Def::Err);
2870             return Def::Err;
2871         }
2872
2873         match def {
2874             Def::Upvar(..) => {
2875                 span_bug!(span, "unexpected {:?} in bindings", def)
2876             }
2877             Def::Local(def_id) => {
2878                 for rib in ribs {
2879                     match rib.kind {
2880                         NormalRibKind | ModuleRibKind(..) | MacroDefinition(..) |
2881                         ForwardTyParamBanRibKind => {
2882                             // Nothing to do. Continue.
2883                         }
2884                         ClosureRibKind(function_id) => {
2885                             let prev_def = def;
2886                             let node_id = self.definitions.as_local_node_id(def_id).unwrap();
2887
2888                             let seen = self.freevars_seen
2889                                            .entry(function_id)
2890                                            .or_insert_with(|| NodeMap());
2891                             if let Some(&index) = seen.get(&node_id) {
2892                                 def = Def::Upvar(def_id, index, function_id);
2893                                 continue;
2894                             }
2895                             let vec = self.freevars
2896                                           .entry(function_id)
2897                                           .or_insert_with(|| vec![]);
2898                             let depth = vec.len();
2899                             def = Def::Upvar(def_id, depth, function_id);
2900
2901                             if record_used {
2902                                 vec.push(Freevar {
2903                                     def: prev_def,
2904                                     span: span,
2905                                 });
2906                                 seen.insert(node_id, depth);
2907                             }
2908                         }
2909                         ItemRibKind | MethodRibKind(_) => {
2910                             // This was an attempt to access an upvar inside a
2911                             // named function item. This is not allowed, so we
2912                             // report an error.
2913                             if record_used {
2914                                 resolve_error(self, span,
2915                                         ResolutionError::CannotCaptureDynamicEnvironmentInFnItem);
2916                             }
2917                             return Def::Err;
2918                         }
2919                         ConstantItemRibKind => {
2920                             // Still doesn't deal with upvars
2921                             if record_used {
2922                                 resolve_error(self, span,
2923                                         ResolutionError::AttemptToUseNonConstantValueInConstant);
2924                             }
2925                             return Def::Err;
2926                         }
2927                     }
2928                 }
2929             }
2930             Def::TyParam(..) | Def::SelfTy(..) => {
2931                 for rib in ribs {
2932                     match rib.kind {
2933                         NormalRibKind | MethodRibKind(_) | ClosureRibKind(..) |
2934                         ModuleRibKind(..) | MacroDefinition(..) | ForwardTyParamBanRibKind |
2935                         ConstantItemRibKind => {
2936                             // Nothing to do. Continue.
2937                         }
2938                         ItemRibKind => {
2939                             // This was an attempt to use a type parameter outside
2940                             // its scope.
2941                             if record_used {
2942                                 resolve_error(self, span,
2943                                               ResolutionError::TypeParametersFromOuterFunction);
2944                             }
2945                             return Def::Err;
2946                         }
2947                     }
2948                 }
2949             }
2950             _ => {}
2951         }
2952         return def;
2953     }
2954
2955     // Calls `f` with a `Resolver` whose current lexical scope is `module`'s lexical scope,
2956     // i.e. the module's items and the prelude (unless the module is `#[no_implicit_prelude]`).
2957     // FIXME #34673: This needs testing.
2958     pub fn with_module_lexical_scope<T, F>(&mut self, module: Module<'a>, f: F) -> T
2959         where F: FnOnce(&mut Resolver<'a>) -> T,
2960     {
2961         self.with_empty_ribs(|this| {
2962             this.ribs[ValueNS].push(Rib::new(ModuleRibKind(module)));
2963             this.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
2964             f(this)
2965         })
2966     }
2967
2968     fn with_empty_ribs<T, F>(&mut self, f: F) -> T
2969         where F: FnOnce(&mut Resolver<'a>) -> T,
2970     {
2971         let ribs = replace(&mut self.ribs, PerNS::<Vec<Rib>>::default());
2972         let label_ribs = replace(&mut self.label_ribs, Vec::new());
2973
2974         let result = f(self);
2975         self.ribs = ribs;
2976         self.label_ribs = label_ribs;
2977         result
2978     }
2979
2980     fn lookup_assoc_candidate<FilterFn>(&mut self,
2981                                         ident: Ident,
2982                                         ns: Namespace,
2983                                         filter_fn: FilterFn)
2984                                         -> Option<AssocSuggestion>
2985         where FilterFn: Fn(Def) -> bool
2986     {
2987         fn extract_node_id(t: &Ty) -> Option<NodeId> {
2988             match t.node {
2989                 TyKind::Path(None, _) => Some(t.id),
2990                 TyKind::Rptr(_, ref mut_ty) => extract_node_id(&mut_ty.ty),
2991                 // This doesn't handle the remaining `Ty` variants as they are not
2992                 // that commonly the self_type, it might be interesting to provide
2993                 // support for those in future.
2994                 _ => None,
2995             }
2996         }
2997
2998         // Fields are generally expected in the same contexts as locals.
2999         if filter_fn(Def::Local(DefId::local(CRATE_DEF_INDEX))) {
3000             if let Some(node_id) = self.current_self_type.as_ref().and_then(extract_node_id) {
3001                 // Look for a field with the same name in the current self_type.
3002                 if let Some(resolution) = self.def_map.get(&node_id) {
3003                     match resolution.base_def() {
3004                         Def::Struct(did) | Def::Union(did)
3005                                 if resolution.unresolved_segments() == 0 => {
3006                             if let Some(field_names) = self.field_names.get(&did) {
3007                                 if field_names.iter().any(|&field_name| ident.name == field_name) {
3008                                     return Some(AssocSuggestion::Field);
3009                                 }
3010                             }
3011                         }
3012                         _ => {}
3013                     }
3014                 }
3015             }
3016         }
3017
3018         // Look for associated items in the current trait.
3019         if let Some((module, _)) = self.current_trait_ref {
3020             if let Ok(binding) =
3021                     self.resolve_ident_in_module(module, ident, ns, false, false, module.span) {
3022                 let def = binding.def();
3023                 if filter_fn(def) {
3024                     return Some(if self.has_self.contains(&def.def_id()) {
3025                         AssocSuggestion::MethodWithSelf
3026                     } else {
3027                         AssocSuggestion::AssocItem
3028                     });
3029                 }
3030             }
3031         }
3032
3033         None
3034     }
3035
3036     fn lookup_typo_candidate<FilterFn>(&mut self,
3037                                        path: &[SpannedIdent],
3038                                        ns: Namespace,
3039                                        filter_fn: FilterFn,
3040                                        span: Span)
3041                                        -> Option<Symbol>
3042         where FilterFn: Fn(Def) -> bool
3043     {
3044         let add_module_candidates = |module: Module, names: &mut Vec<Name>| {
3045             for (&(ident, _), resolution) in module.resolutions.borrow().iter() {
3046                 if let Some(binding) = resolution.borrow().binding {
3047                     if filter_fn(binding.def()) {
3048                         names.push(ident.name);
3049                     }
3050                 }
3051             }
3052         };
3053
3054         let mut names = Vec::new();
3055         if path.len() == 1 {
3056             // Search in lexical scope.
3057             // Walk backwards up the ribs in scope and collect candidates.
3058             for rib in self.ribs[ns].iter().rev() {
3059                 // Locals and type parameters
3060                 for (ident, def) in &rib.bindings {
3061                     if filter_fn(*def) {
3062                         names.push(ident.name);
3063                     }
3064                 }
3065                 // Items in scope
3066                 if let ModuleRibKind(module) = rib.kind {
3067                     // Items from this module
3068                     add_module_candidates(module, &mut names);
3069
3070                     if let ModuleKind::Block(..) = module.kind {
3071                         // We can see through blocks
3072                     } else {
3073                         // Items from the prelude
3074                         if let Some(prelude) = self.prelude {
3075                             if !module.no_implicit_prelude {
3076                                 add_module_candidates(prelude, &mut names);
3077                             }
3078                         }
3079                         break;
3080                     }
3081                 }
3082             }
3083             // Add primitive types to the mix
3084             if filter_fn(Def::PrimTy(TyBool)) {
3085                 for (name, _) in &self.primitive_type_table.primitive_types {
3086                     names.push(*name);
3087                 }
3088             }
3089         } else {
3090             // Search in module.
3091             let mod_path = &path[..path.len() - 1];
3092             if let PathResult::Module(module) = self.resolve_path(mod_path, Some(TypeNS),
3093                                                                   false, span) {
3094                 add_module_candidates(module, &mut names);
3095             }
3096         }
3097
3098         let name = path[path.len() - 1].node.name;
3099         // Make sure error reporting is deterministic.
3100         names.sort_by_key(|name| name.as_str());
3101         match find_best_match_for_name(names.iter(), &name.as_str(), None) {
3102             Some(found) if found != name => Some(found),
3103             _ => None,
3104         }
3105     }
3106
3107     fn with_resolved_label<F>(&mut self, label: Option<SpannedIdent>, id: NodeId, f: F)
3108         where F: FnOnce(&mut Resolver)
3109     {
3110         if let Some(label) = label {
3111             let def = Def::Label(id);
3112             self.with_label_rib(|this| {
3113                 this.label_ribs.last_mut().unwrap().bindings.insert(label.node, def);
3114                 f(this);
3115             });
3116         } else {
3117             f(self);
3118         }
3119     }
3120
3121     fn resolve_labeled_block(&mut self, label: Option<SpannedIdent>, id: NodeId, block: &Block) {
3122         self.with_resolved_label(label, id, |this| this.visit_block(block));
3123     }
3124
3125     fn resolve_expr(&mut self, expr: &Expr, parent: Option<&Expr>) {
3126         // First, record candidate traits for this expression if it could
3127         // result in the invocation of a method call.
3128
3129         self.record_candidate_traits_for_expr_if_necessary(expr);
3130
3131         // Next, resolve the node.
3132         match expr.node {
3133             ExprKind::Path(ref qself, ref path) => {
3134                 self.smart_resolve_path(expr.id, qself.as_ref(), path, PathSource::Expr(parent));
3135                 visit::walk_expr(self, expr);
3136             }
3137
3138             ExprKind::Struct(ref path, ..) => {
3139                 self.smart_resolve_path(expr.id, None, path, PathSource::Struct);
3140                 visit::walk_expr(self, expr);
3141             }
3142
3143             ExprKind::Break(Some(label), _) | ExprKind::Continue(Some(label)) => {
3144                 match self.search_label(label.node) {
3145                     None => {
3146                         self.record_def(expr.id, err_path_resolution());
3147                         resolve_error(self,
3148                                       label.span,
3149                                       ResolutionError::UndeclaredLabel(&label.node.name.as_str()));
3150                     }
3151                     Some(def @ Def::Label(_)) => {
3152                         // Since this def is a label, it is never read.
3153                         self.record_def(expr.id, PathResolution::new(def));
3154                     }
3155                     Some(_) => {
3156                         span_bug!(expr.span, "label wasn't mapped to a label def!");
3157                     }
3158                 }
3159
3160                 // visit `break` argument if any
3161                 visit::walk_expr(self, expr);
3162             }
3163
3164             ExprKind::IfLet(ref pattern, ref subexpression, ref if_block, ref optional_else) => {
3165                 self.visit_expr(subexpression);
3166
3167                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3168                 self.resolve_pattern(pattern, PatternSource::IfLet, &mut FxHashMap());
3169                 self.visit_block(if_block);
3170                 self.ribs[ValueNS].pop();
3171
3172                 optional_else.as_ref().map(|expr| self.visit_expr(expr));
3173             }
3174
3175             ExprKind::Loop(ref block, label) => self.resolve_labeled_block(label, expr.id, &block),
3176
3177             ExprKind::While(ref subexpression, ref block, label) => {
3178                 self.with_resolved_label(label, expr.id, |this| {
3179                     this.visit_expr(subexpression);
3180                     this.visit_block(block);
3181                 });
3182             }
3183
3184             ExprKind::WhileLet(ref pattern, ref subexpression, ref block, label) => {
3185                 self.with_resolved_label(label, expr.id, |this| {
3186                     this.visit_expr(subexpression);
3187                     this.ribs[ValueNS].push(Rib::new(NormalRibKind));
3188                     this.resolve_pattern(pattern, PatternSource::WhileLet, &mut FxHashMap());
3189                     this.visit_block(block);
3190                     this.ribs[ValueNS].pop();
3191                 });
3192             }
3193
3194             ExprKind::ForLoop(ref pattern, ref subexpression, ref block, label) => {
3195                 self.visit_expr(subexpression);
3196                 self.ribs[ValueNS].push(Rib::new(NormalRibKind));
3197                 self.resolve_pattern(pattern, PatternSource::For, &mut FxHashMap());
3198
3199                 self.resolve_labeled_block(label, expr.id, block);
3200
3201                 self.ribs[ValueNS].pop();
3202             }
3203
3204             // Equivalent to `visit::walk_expr` + passing some context to children.
3205             ExprKind::Field(ref subexpression, _) => {
3206                 self.resolve_expr(subexpression, Some(expr));
3207             }
3208             ExprKind::MethodCall(ref segment, ref arguments) => {
3209                 let mut arguments = arguments.iter();
3210                 self.resolve_expr(arguments.next().unwrap(), Some(expr));
3211                 for argument in arguments {
3212                     self.resolve_expr(argument, None);
3213                 }
3214                 self.visit_path_segment(expr.span, segment);
3215             }
3216
3217             ExprKind::Repeat(ref element, ref count) => {
3218                 self.visit_expr(element);
3219                 self.with_constant_rib(|this| {
3220                     this.visit_expr(count);
3221                 });
3222             }
3223             ExprKind::Call(ref callee, ref arguments) => {
3224                 self.resolve_expr(callee, Some(expr));
3225                 for argument in arguments {
3226                     self.resolve_expr(argument, None);
3227                 }
3228             }
3229             ExprKind::Type(ref type_expr, _) => {
3230                 self.current_type_ascription.push(type_expr.span);
3231                 visit::walk_expr(self, expr);
3232                 self.current_type_ascription.pop();
3233             }
3234             _ => {
3235                 visit::walk_expr(self, expr);
3236             }
3237         }
3238     }
3239
3240     fn record_candidate_traits_for_expr_if_necessary(&mut self, expr: &Expr) {
3241         match expr.node {
3242             ExprKind::Field(_, name) => {
3243                 // FIXME(#6890): Even though you can't treat a method like a
3244                 // field, we need to add any trait methods we find that match
3245                 // the field name so that we can do some nice error reporting
3246                 // later on in typeck.
3247                 let traits = self.get_traits_containing_item(name.node, ValueNS);
3248                 self.trait_map.insert(expr.id, traits);
3249             }
3250             ExprKind::MethodCall(ref segment, ..) => {
3251                 debug!("(recording candidate traits for expr) recording traits for {}",
3252                        expr.id);
3253                 let traits = self.get_traits_containing_item(segment.identifier, ValueNS);
3254                 self.trait_map.insert(expr.id, traits);
3255             }
3256             _ => {
3257                 // Nothing to do.
3258             }
3259         }
3260     }
3261
3262     fn get_traits_containing_item(&mut self, mut ident: Ident, ns: Namespace)
3263                                   -> Vec<TraitCandidate> {
3264         debug!("(getting traits containing item) looking for '{}'", ident.name);
3265
3266         let mut found_traits = Vec::new();
3267         // Look for the current trait.
3268         if let Some((module, _)) = self.current_trait_ref {
3269             if self.resolve_ident_in_module(module, ident, ns, false, false, module.span).is_ok() {
3270                 let def_id = module.def_id().unwrap();
3271                 found_traits.push(TraitCandidate { def_id: def_id, import_id: None });
3272             }
3273         }
3274
3275         ident.ctxt = ident.ctxt.modern();
3276         let mut search_module = self.current_module;
3277         loop {
3278             self.get_traits_in_module_containing_item(ident, ns, search_module, &mut found_traits);
3279             search_module =
3280                 unwrap_or!(self.hygienic_lexical_parent(search_module, &mut ident.ctxt), break);
3281         }
3282
3283         if let Some(prelude) = self.prelude {
3284             if !search_module.no_implicit_prelude {
3285                 self.get_traits_in_module_containing_item(ident, ns, prelude, &mut found_traits);
3286             }
3287         }
3288
3289         found_traits
3290     }
3291
3292     fn get_traits_in_module_containing_item(&mut self,
3293                                             ident: Ident,
3294                                             ns: Namespace,
3295                                             module: Module<'a>,
3296                                             found_traits: &mut Vec<TraitCandidate>) {
3297         let mut traits = module.traits.borrow_mut();
3298         if traits.is_none() {
3299             let mut collected_traits = Vec::new();
3300             module.for_each_child(|name, ns, binding| {
3301                 if ns != TypeNS { return }
3302                 if let Def::Trait(_) = binding.def() {
3303                     collected_traits.push((name, binding));
3304                 }
3305             });
3306             *traits = Some(collected_traits.into_boxed_slice());
3307         }
3308
3309         for &(trait_name, binding) in traits.as_ref().unwrap().iter() {
3310             let module = binding.module().unwrap();
3311             let mut ident = ident;
3312             if ident.ctxt.glob_adjust(module.expansion, binding.span.ctxt.modern()).is_none() {
3313                 continue
3314             }
3315             if self.resolve_ident_in_module_unadjusted(module, ident, ns, false, false, module.span)
3316                    .is_ok() {
3317                 let import_id = match binding.kind {
3318                     NameBindingKind::Import { directive, .. } => {
3319                         self.maybe_unused_trait_imports.insert(directive.id);
3320                         self.add_to_glob_map(directive.id, trait_name);
3321                         Some(directive.id)
3322                     }
3323                     _ => None,
3324                 };
3325                 let trait_def_id = module.def_id().unwrap();
3326                 found_traits.push(TraitCandidate { def_id: trait_def_id, import_id: import_id });
3327             }
3328         }
3329     }
3330
3331     /// When name resolution fails, this method can be used to look up candidate
3332     /// entities with the expected name. It allows filtering them using the
3333     /// supplied predicate (which should be used to only accept the types of
3334     /// definitions expected e.g. traits). The lookup spans across all crates.
3335     ///
3336     /// NOTE: The method does not look into imports, but this is not a problem,
3337     /// since we report the definitions (thus, the de-aliased imports).
3338     fn lookup_import_candidates<FilterFn>(&mut self,
3339                                           lookup_name: Name,
3340                                           namespace: Namespace,
3341                                           filter_fn: FilterFn)
3342                                           -> Vec<ImportSuggestion>
3343         where FilterFn: Fn(Def) -> bool
3344     {
3345         let mut candidates = Vec::new();
3346         let mut worklist = Vec::new();
3347         let mut seen_modules = FxHashSet();
3348         worklist.push((self.graph_root, Vec::new(), false));
3349
3350         while let Some((in_module,
3351                         path_segments,
3352                         in_module_is_extern)) = worklist.pop() {
3353             self.populate_module_if_necessary(in_module);
3354
3355             in_module.for_each_child(|ident, ns, name_binding| {
3356
3357                 // avoid imports entirely
3358                 if name_binding.is_import() && !name_binding.is_extern_crate() { return; }
3359                 // avoid non-importable candidates as well
3360                 if !name_binding.is_importable() { return; }
3361
3362                 // collect results based on the filter function
3363                 if ident.name == lookup_name && ns == namespace {
3364                     if filter_fn(name_binding.def()) {
3365                         // create the path
3366                         let mut segms = path_segments.clone();
3367                         segms.push(ast::PathSegment::from_ident(ident, name_binding.span));
3368                         let path = Path {
3369                             span: name_binding.span,
3370                             segments: segms,
3371                         };
3372                         // the entity is accessible in the following cases:
3373                         // 1. if it's defined in the same crate, it's always
3374                         // accessible (since private entities can be made public)
3375                         // 2. if it's defined in another crate, it's accessible
3376                         // only if both the module is public and the entity is
3377                         // declared as public (due to pruning, we don't explore
3378                         // outside crate private modules => no need to check this)
3379                         if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3380                             candidates.push(ImportSuggestion { path: path });
3381                         }
3382                     }
3383                 }
3384
3385                 // collect submodules to explore
3386                 if let Some(module) = name_binding.module() {
3387                     // form the path
3388                     let mut path_segments = path_segments.clone();
3389                     path_segments.push(ast::PathSegment::from_ident(ident, name_binding.span));
3390
3391                     if !in_module_is_extern || name_binding.vis == ty::Visibility::Public {
3392                         // add the module to the lookup
3393                         let is_extern = in_module_is_extern || name_binding.is_extern_crate();
3394                         if seen_modules.insert(module.def_id().unwrap()) {
3395                             worklist.push((module, path_segments, is_extern));
3396                         }
3397                     }
3398                 }
3399             })
3400         }
3401
3402         candidates
3403     }
3404
3405     fn record_def(&mut self, node_id: NodeId, resolution: PathResolution) {
3406         debug!("(recording def) recording {:?} for {}", resolution, node_id);
3407         if let Some(prev_res) = self.def_map.insert(node_id, resolution) {
3408             panic!("path resolved multiple times ({:?} before, {:?} now)", prev_res, resolution);
3409         }
3410     }
3411
3412     fn resolve_visibility(&mut self, vis: &ast::Visibility) -> ty::Visibility {
3413         match *vis {
3414             ast::Visibility::Public => ty::Visibility::Public,
3415             ast::Visibility::Crate(..) => ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
3416             ast::Visibility::Inherited => {
3417                 ty::Visibility::Restricted(self.current_module.normal_ancestor_id)
3418             }
3419             ast::Visibility::Restricted { ref path, id } => {
3420                 let def = self.smart_resolve_path(id, None, path,
3421                                                   PathSource::Visibility).base_def();
3422                 if def == Def::Err {
3423                     ty::Visibility::Public
3424                 } else {
3425                     let vis = ty::Visibility::Restricted(def.def_id());
3426                     if self.is_accessible(vis) {
3427                         vis
3428                     } else {
3429                         self.session.span_err(path.span, "visibilities can only be restricted \
3430                                                           to ancestor modules");
3431                         ty::Visibility::Public
3432                     }
3433                 }
3434             }
3435         }
3436     }
3437
3438     fn is_accessible(&self, vis: ty::Visibility) -> bool {
3439         vis.is_accessible_from(self.current_module.normal_ancestor_id, self)
3440     }
3441
3442     fn is_accessible_from(&self, vis: ty::Visibility, module: Module<'a>) -> bool {
3443         vis.is_accessible_from(module.normal_ancestor_id, self)
3444     }
3445
3446     fn report_errors(&mut self) {
3447         self.report_shadowing_errors();
3448         let mut reported_spans = FxHashSet();
3449
3450         for &AmbiguityError { span, name, b1, b2, lexical, legacy } in &self.ambiguity_errors {
3451             if !reported_spans.insert(span) { continue }
3452             let participle = |binding: &NameBinding| {
3453                 if binding.is_import() { "imported" } else { "defined" }
3454             };
3455             let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
3456             let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
3457             let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
3458                 format!("consider adding an explicit import of `{}` to disambiguate", name)
3459             } else if let Def::Macro(..) = b1.def() {
3460                 format!("macro-expanded {} do not shadow",
3461                         if b1.is_import() { "macro imports" } else { "macros" })
3462             } else {
3463                 format!("macro-expanded {} do not shadow when used in a macro invocation path",
3464                         if b1.is_import() { "imports" } else { "items" })
3465             };
3466             if legacy {
3467                 let id = match b2.kind {
3468                     NameBindingKind::Import { directive, .. } => directive.id,
3469                     _ => unreachable!(),
3470                 };
3471                 let mut span = MultiSpan::from_span(span);
3472                 span.push_span_label(b1.span, msg1);
3473                 span.push_span_label(b2.span, msg2);
3474                 let msg = format!("`{}` is ambiguous", name);
3475                 self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3476             } else {
3477                 let mut err =
3478                     self.session.struct_span_err(span, &format!("`{}` is ambiguous", name));
3479                 err.span_note(b1.span, &msg1);
3480                 match b2.def() {
3481                     Def::Macro(..) if b2.span == DUMMY_SP =>
3482                         err.note(&format!("`{}` is also a builtin macro", name)),
3483                     _ => err.span_note(b2.span, &msg2),
3484                 };
3485                 err.note(&note).emit();
3486             }
3487         }
3488
3489         for &PrivacyError(span, name, binding) in &self.privacy_errors {
3490             if !reported_spans.insert(span) { continue }
3491             span_err!(self.session, span, E0603, "{} `{}` is private", binding.descr(), name);
3492         }
3493     }
3494
3495     fn report_shadowing_errors(&mut self) {
3496         for (ident, scope) in replace(&mut self.lexical_macro_resolutions, Vec::new()) {
3497             self.resolve_legacy_scope(scope, ident, true);
3498         }
3499
3500         let mut reported_errors = FxHashSet();
3501         for binding in replace(&mut self.disallowed_shadowing, Vec::new()) {
3502             if self.resolve_legacy_scope(&binding.parent, binding.ident, false).is_some() &&
3503                reported_errors.insert((binding.ident, binding.span)) {
3504                 let msg = format!("`{}` is already in scope", binding.ident);
3505                 self.session.struct_span_err(binding.span, &msg)
3506                     .note("macro-expanded `macro_rules!`s may not shadow \
3507                            existing macros (see RFC 1560)")
3508                     .emit();
3509             }
3510         }
3511     }
3512
3513     fn report_conflict(&mut self,
3514                        parent: Module,
3515                        ident: Ident,
3516                        ns: Namespace,
3517                        new_binding: &NameBinding,
3518                        old_binding: &NameBinding) {
3519         // Error on the second of two conflicting names
3520         if old_binding.span.lo > new_binding.span.lo {
3521             return self.report_conflict(parent, ident, ns, old_binding, new_binding);
3522         }
3523
3524         let container = match parent.kind {
3525             ModuleKind::Def(Def::Mod(_), _) => "module",
3526             ModuleKind::Def(Def::Trait(_), _) => "trait",
3527             ModuleKind::Block(..) => "block",
3528             _ => "enum",
3529         };
3530
3531         let old_noun = match old_binding.is_import() {
3532             true => "import",
3533             false => "definition",
3534         };
3535
3536         let new_participle = match new_binding.is_import() {
3537             true => "imported",
3538             false => "defined",
3539         };
3540
3541         let (name, span) = (ident.name, new_binding.span);
3542
3543         if let Some(s) = self.name_already_seen.get(&name) {
3544             if s == &span {
3545                 return;
3546             }
3547         }
3548
3549         let old_kind = match (ns, old_binding.module()) {
3550             (ValueNS, _) => "value",
3551             (MacroNS, _) => "macro",
3552             (TypeNS, _) if old_binding.is_extern_crate() => "extern crate",
3553             (TypeNS, Some(module)) if module.is_normal() => "module",
3554             (TypeNS, Some(module)) if module.is_trait() => "trait",
3555             (TypeNS, _) => "type",
3556         };
3557
3558         let namespace = match ns {
3559             ValueNS => "value",
3560             MacroNS => "macro",
3561             TypeNS => "type",
3562         };
3563
3564         let msg = format!("the name `{}` is defined multiple times", name);
3565
3566         let mut err = match (old_binding.is_extern_crate(), new_binding.is_extern_crate()) {
3567             (true, true) => struct_span_err!(self.session, span, E0259, "{}", msg),
3568             (true, _) | (_, true) => match new_binding.is_import() && old_binding.is_import() {
3569                 true => struct_span_err!(self.session, span, E0254, "{}", msg),
3570                 false => struct_span_err!(self.session, span, E0260, "{}", msg),
3571             },
3572             _ => match (old_binding.is_import(), new_binding.is_import()) {
3573                 (false, false) => struct_span_err!(self.session, span, E0428, "{}", msg),
3574                 (true, true) => struct_span_err!(self.session, span, E0252, "{}", msg),
3575                 _ => struct_span_err!(self.session, span, E0255, "{}", msg),
3576             },
3577         };
3578
3579         err.note(&format!("`{}` must be defined only once in the {} namespace of this {}",
3580                           name,
3581                           namespace,
3582                           container));
3583
3584         err.span_label(span, format!("`{}` re{} here", name, new_participle));
3585         if old_binding.span != syntax_pos::DUMMY_SP {
3586             err.span_label(old_binding.span, format!("previous {} of the {} `{}` here",
3587                                                       old_noun, old_kind, name));
3588         }
3589
3590         err.emit();
3591         self.name_already_seen.insert(name, span);
3592     }
3593
3594     fn warn_legacy_self_import(&self, directive: &'a ImportDirective<'a>) {
3595         let (id, span) = (directive.id, directive.span);
3596         let msg = "`self` no longer imports values".to_string();
3597         self.session.add_lint(lint::builtin::LEGACY_IMPORTS, id, span, msg);
3598     }
3599
3600     fn check_proc_macro_attrs(&mut self, attrs: &[ast::Attribute]) {
3601         if self.proc_macro_enabled { return; }
3602
3603         for attr in attrs {
3604             if attr.path.segments.len() > 1 {
3605                 continue
3606             }
3607             let ident = attr.path.segments[0].identifier;
3608             let result = self.resolve_lexical_macro_path_segment(ident,
3609                                                                  MacroNS,
3610                                                                  false,
3611                                                                  attr.path.span);
3612             if let Ok(binding) = result {
3613                 if let SyntaxExtension::AttrProcMacro(..) = *binding.binding().get_macro(self) {
3614                     attr::mark_known(attr);
3615
3616                     let msg = "attribute procedural macros are experimental";
3617                     let feature = "proc_macro";
3618
3619                     feature_err(&self.session.parse_sess, feature,
3620                                 attr.span, GateIssue::Language, msg)
3621                         .span_note(binding.span(), "procedural macro imported here")
3622                         .emit();
3623                 }
3624             }
3625         }
3626     }
3627 }
3628
3629 fn is_struct_like(def: Def) -> bool {
3630     match def {
3631         Def::VariantCtor(_, CtorKind::Fictive) => true,
3632         _ => PathSource::Struct.is_expected(def),
3633     }
3634 }
3635
3636 fn is_self_type(path: &[SpannedIdent], namespace: Namespace) -> bool {
3637     namespace == TypeNS && path.len() == 1 && path[0].node.name == keywords::SelfType.name()
3638 }
3639
3640 fn is_self_value(path: &[SpannedIdent], namespace: Namespace) -> bool {
3641     namespace == ValueNS && path.len() == 1 && path[0].node.name == keywords::SelfValue.name()
3642 }
3643
3644 fn names_to_string(idents: &[SpannedIdent]) -> String {
3645     let mut result = String::new();
3646     for (i, ident) in idents.iter()
3647                             .filter(|i| i.node.name != keywords::CrateRoot.name())
3648                             .enumerate() {
3649         if i > 0 {
3650             result.push_str("::");
3651         }
3652         result.push_str(&ident.node.name.as_str());
3653     }
3654     result
3655 }
3656
3657 fn path_names_to_string(path: &Path) -> String {
3658     names_to_string(&path.segments.iter()
3659                         .map(|seg| respan(seg.span, seg.identifier))
3660                         .collect::<Vec<_>>())
3661 }
3662
3663 /// Get the path for an enum and the variant from an `ImportSuggestion` for an enum variant.
3664 fn import_candidate_to_paths(suggestion: &ImportSuggestion) -> (Span, String, String) {
3665     let variant_path = &suggestion.path;
3666     let variant_path_string = path_names_to_string(variant_path);
3667
3668     let path_len = suggestion.path.segments.len();
3669     let enum_path = ast::Path {
3670         span: suggestion.path.span,
3671         segments: suggestion.path.segments[0..path_len - 1].to_vec(),
3672     };
3673     let enum_path_string = path_names_to_string(&enum_path);
3674
3675     (suggestion.path.span, variant_path_string, enum_path_string)
3676 }
3677
3678
3679 /// When an entity with a given name is not available in scope, we search for
3680 /// entities with that name in all crates. This method allows outputting the
3681 /// results of this search in a programmer-friendly way
3682 fn show_candidates(err: &mut DiagnosticBuilder,
3683                    span: Span,
3684                    candidates: &[ImportSuggestion],
3685                    better: bool) {
3686
3687     // we want consistent results across executions, but candidates are produced
3688     // by iterating through a hash map, so make sure they are ordered:
3689     let mut path_strings: Vec<_> =
3690         candidates.into_iter().map(|c| path_names_to_string(&c.path)).collect();
3691     path_strings.sort();
3692
3693     let better = if better { "better " } else { "" };
3694     let msg_diff = match path_strings.len() {
3695         1 => " is found in another module, you can import it",
3696         _ => "s are found in other modules, you can import them",
3697     };
3698     let msg = format!("possible {}candidate{} into scope", better, msg_diff);
3699
3700     for candidate in &mut path_strings {
3701         *candidate = format!("use {};\n", candidate);
3702     }
3703
3704     err.span_suggestions(span, &msg, path_strings);
3705 }
3706
3707 /// A somewhat inefficient routine to obtain the name of a module.
3708 fn module_to_string(module: Module) -> String {
3709     let mut names = Vec::new();
3710
3711     fn collect_mod(names: &mut Vec<Ident>, module: Module) {
3712         if let ModuleKind::Def(_, name) = module.kind {
3713             if let Some(parent) = module.parent {
3714                 names.push(Ident::with_empty_ctxt(name));
3715                 collect_mod(names, parent);
3716             }
3717         } else {
3718             // danger, shouldn't be ident?
3719             names.push(Ident::from_str("<opaque>"));
3720             collect_mod(names, module.parent.unwrap());
3721         }
3722     }
3723     collect_mod(&mut names, module);
3724
3725     if names.is_empty() {
3726         return "???".to_string();
3727     }
3728     names_to_string(&names.into_iter()
3729                         .rev()
3730                         .map(|n| dummy_spanned(n))
3731                         .collect::<Vec<_>>())
3732 }
3733
3734 fn err_path_resolution() -> PathResolution {
3735     PathResolution::new(Def::Err)
3736 }
3737
3738 #[derive(PartialEq,Copy, Clone)]
3739 pub enum MakeGlobMap {
3740     Yes,
3741     No,
3742 }
3743
3744 __build_diagnostic_array! { librustc_resolve, DIAGNOSTICS }