src/librustc/hir/mod.rs

   1 // Copyright 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 // The Rust HIR.
  12
  13 pub use self::BinOp_::*;
  14 pub use self::BlockCheckMode::*;
  15 pub use self::CaptureClause::*;
  16 pub use self::Decl_::*;
  17 pub use self::Expr_::*;
  18 pub use self::FunctionRetTy::*;
  19 pub use self::ForeignItem_::*;
  20 pub use self::Item_::*;
  21 pub use self::Mutability::*;
  22 pub use self::PrimTy::*;
  23 pub use self::Stmt_::*;
  24 pub use self::Ty_::*;
  25 pub use self::TyParamBound::*;
  26 pub use self::UnOp::*;
  27 pub use self::UnsafeSource::*;
  28 pub use self::Visibility::{Public, Inherited};
  29
  30 use hir::def::Def;
  31 use hir::def_id::{DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX};
  32 use util::nodemap::{NodeMap, FxHashSet};
  33 use mir::mono::Linkage;
  34
  35 use syntax_pos::{Span, DUMMY_SP};
  36 use syntax::codemap::{self, Spanned};
  37 use rustc_target::spec::abi::Abi;
  38 use syntax::ast::{self, CrateSugar, Ident, Name, NodeId, DUMMY_NODE_ID, AsmDialect};
  39 use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy, MetaItem};
  40 use syntax::attr::InlineAttr;
  41 use syntax::ext::hygiene::SyntaxContext;
  42 use syntax::ptr::P;
  43 use syntax::symbol::{Symbol, keywords};
  44 use syntax::tokenstream::TokenStream;
  45 use syntax::util::ThinVec;
  46 use syntax::util::parser::ExprPrecedence;
  47 use ty::AdtKind;
  48 use ty::query::Providers;
  49
  50 use rustc_data_structures::indexed_vec;
  51 use rustc_data_structures::sync::{ParallelIterator, par_iter, Send, Sync, scope};
  52
  53 use serialize::{self, Encoder, Encodable, Decoder, Decodable};
  54 use std::collections::BTreeMap;
  55 use std::fmt;
  56 use std::iter;
  57 use std::slice;
  58
  59 /// HIR doesn't commit to a concrete storage type and has its own alias for a vector.
  60 /// It can be `Vec`, `P<[T]>` or potentially `Box<[T]>`, or some other container with similar
  61 /// behavior. Unlike AST, HIR is mostly a static structure, so we can use an owned slice instead
  62 /// of `Vec` to avoid keeping extra capacity.
  63 pub type HirVec<T> = P<[T]>;
  64
  65 macro_rules! hir_vec {
  66     ($elem:expr; $n:expr) => (
  67         $crate::hir::HirVec::from(vec![$elem; $n])
  68     );
  69     ($($x:expr),*) => (
  70         $crate::hir::HirVec::from(vec![$($x),*])
  71     );
  72     ($($x:expr,)*) => (hir_vec![$($x),*])
  73 }
  74
  75 pub mod check_attr;
  76 pub mod def;
  77 pub mod def_id;
  78 pub mod intravisit;
  79 pub mod itemlikevisit;
  80 pub mod lowering;
  81 pub mod map;
  82 pub mod pat_util;
  83 pub mod print;
  84 pub mod svh;
  85
  86 /// A HirId uniquely identifies a node in the HIR of the current crate. It is
  87 /// composed of the `owner`, which is the DefIndex of the directly enclosing
  88 /// hir::Item, hir::TraitItem, or hir::ImplItem (i.e. the closest "item-like"),
  89 /// and the `local_id` which is unique within the given owner.
  90 ///
  91 /// This two-level structure makes for more stable values: One can move an item
  92 /// around within the source code, or add or remove stuff before it, without
  93 /// the local_id part of the HirId changing, which is a very useful property in
  94 /// incremental compilation where we have to persist things through changes to
  95 /// the code base.
  96 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
  97 pub struct HirId {
  98     pub owner: DefIndex,
  99     pub local_id: ItemLocalId,
 100 }
 101
 102 impl HirId {
 103     pub fn owner_def_id(self) -> DefId {
 104         DefId::local(self.owner)
 105     }
 106
 107     pub fn owner_local_def_id(self) -> LocalDefId {
 108         LocalDefId::from_def_id(DefId::local(self.owner))
 109     }
 110 }
 111
 112 impl serialize::UseSpecializedEncodable for HirId {
 113     fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
 114         let HirId {
 115             owner,
 116             local_id,
 117         } = *self;
 118
 119         owner.encode(s)?;
 120         local_id.encode(s)
 121     }
 122 }
 123
 124 impl serialize::UseSpecializedDecodable for HirId {
 125     fn default_decode<D: Decoder>(d: &mut D) -> Result<HirId, D::Error> {
 126         let owner = DefIndex::decode(d)?;
 127         let local_id = ItemLocalId::decode(d)?;
 128
 129         Ok(HirId {
 130             owner,
 131             local_id
 132         })
 133     }
 134 }
 135
 136
 137 /// An `ItemLocalId` uniquely identifies something within a given "item-like",
 138 /// that is within a hir::Item, hir::TraitItem, or hir::ImplItem. There is no
 139 /// guarantee that the numerical value of a given `ItemLocalId` corresponds to
 140 /// the node's position within the owning item in any way, but there is a
 141 /// guarantee that the `LocalItemId`s within an owner occupy a dense range of
 142 /// integers starting at zero, so a mapping that maps all or most nodes within
 143 /// an "item-like" to something else can be implement by a `Vec` instead of a
 144 /// tree or hash map.
 145 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug,
 146          RustcEncodable, RustcDecodable)]
 147 pub struct ItemLocalId(pub u32);
 148
 149 impl ItemLocalId {
 150     pub fn as_usize(&self) -> usize {
 151         self.0 as usize
 152     }
 153 }
 154
 155 impl indexed_vec::Idx for ItemLocalId {
 156     fn new(idx: usize) -> Self {
 157         debug_assert!((idx as u32) as usize == idx);
 158         ItemLocalId(idx as u32)
 159     }
 160
 161     fn index(self) -> usize {
 162         self.0 as usize
 163     }
 164 }
 165
 166 /// The `HirId` corresponding to CRATE_NODE_ID and CRATE_DEF_INDEX
 167 pub const CRATE_HIR_ID: HirId = HirId {
 168     owner: CRATE_DEF_INDEX,
 169     local_id: ItemLocalId(0)
 170 };
 171
 172 pub const DUMMY_HIR_ID: HirId = HirId {
 173     owner: CRATE_DEF_INDEX,
 174     local_id: DUMMY_ITEM_LOCAL_ID,
 175 };
 176
 177 pub const DUMMY_ITEM_LOCAL_ID: ItemLocalId = ItemLocalId(!0);
 178
 179 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
 180 pub struct Label {
 181     pub name: Name,
 182     pub span: Span,
 183 }
 184
 185 impl fmt::Debug for Label {
 186     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 187         write!(f, "label({:?})", self.name)
 188     }
 189 }
 190
 191 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
 192 pub struct Lifetime {
 193     pub id: NodeId,
 194     pub span: Span,
 195
 196     /// Either "'a", referring to a named lifetime definition,
 197     /// or "" (aka keywords::Invalid), for elision placeholders.
 198     ///
 199     /// HIR lowering inserts these placeholders in type paths that
 200     /// refer to type definitions needing lifetime parameters,
 201     /// `&T` and `&mut T`, and trait objects without `... + 'a`.
 202     pub name: LifetimeName,
 203 }
 204
 205 #[derive(Debug, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
 206 pub enum LifetimeName {
 207     /// User typed nothing. e.g. the lifetime in `&u32`.
 208     Implicit,
 209
 210     /// User typed `'_`.
 211     Underscore,
 212
 213     /// Synthetic name generated when user elided a lifetime in an impl header,
 214     /// e.g. the lifetimes in cases like these:
 215     ///
 216     ///     impl Foo for &u32
 217     ///     impl Foo<'_> for u32
 218     ///
 219     /// in that case, we rewrite to
 220     ///
 221     ///     impl<'f> Foo for &'f u32
 222     ///     impl<'f> Foo<'f> for u32
 223     ///
 224     /// where `'f` is something like `Fresh(0)`. The indices are
 225     /// unique per impl, but not necessarily continuous.
 226     Fresh(usize),
 227
 228     /// User wrote `'static`
 229     Static,
 230
 231     /// Some user-given name like `'x`
 232     Name(Name),
 233 }
 234
 235 impl LifetimeName {
 236     pub fn name(&self) -> Name {
 237         use self::LifetimeName::*;
 238         match *self {
 239             Implicit => keywords::Invalid.name(),
 240             Fresh(_) | Underscore => keywords::UnderscoreLifetime.name(),
 241             Static => keywords::StaticLifetime.name(),
 242             Name(name) => name,
 243         }
 244     }
 245 }
 246
 247 impl fmt::Debug for Lifetime {
 248     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 249         write!(f,
 250                "lifetime({}: {})",
 251                self.id,
 252                print::to_string(print::NO_ANN, |s| s.print_lifetime(self)))
 253     }
 254 }
 255
 256 impl Lifetime {
 257     pub fn is_elided(&self) -> bool {
 258         use self::LifetimeName::*;
 259         match self.name {
 260             Implicit | Underscore => true,
 261
 262             // It might seem surprising that `Fresh(_)` counts as
 263             // *not* elided -- but this is because, as far as the code
 264             // in the compiler is concerned -- `Fresh(_)` variants act
 265             // equivalently to "some fresh name". They correspond to
 266             // early-bound regions on an impl, in other words.
 267             Fresh(_) | Static | Name(_) => false,
 268         }
 269     }
 270
 271     pub fn is_static(&self) -> bool {
 272         self.name == LifetimeName::Static
 273     }
 274 }
 275
 276 /// A lifetime definition, eg `'a: 'b+'c+'d`
 277 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 278 pub struct LifetimeDef {
 279     pub lifetime: Lifetime,
 280     pub bounds: HirVec<Lifetime>,
 281     pub pure_wrt_drop: bool,
 282     // Indicates that the lifetime definition was synthetically added
 283     // as a result of an in-band lifetime usage like
 284     // `fn foo(x: &'a u8) -> &'a u8 { x }`
 285     pub in_band: bool,
 286 }
 287
 288 /// A "Path" is essentially Rust's notion of a name; for instance:
 289 /// `std::cmp::PartialEq`. It's represented as a sequence of identifiers,
 290 /// along with a bunch of supporting information.
 291 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 292 pub struct Path {
 293     pub span: Span,
 294     /// The definition that the path resolved to.
 295     pub def: Def,
 296     /// The segments in the path: the things separated by `::`.
 297     pub segments: HirVec<PathSegment>,
 298 }
 299
 300 impl Path {
 301     pub fn is_global(&self) -> bool {
 302         !self.segments.is_empty() && self.segments[0].name == keywords::CrateRoot.name()
 303     }
 304 }
 305
 306 impl fmt::Debug for Path {
 307     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 308         write!(f, "path({})", print::to_string(print::NO_ANN, |s| s.print_path(self, false)))
 309     }
 310 }
 311
 312 impl fmt::Display for Path {
 313     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 314         write!(f, "{}", print::to_string(print::NO_ANN, |s| s.print_path(self, false)))
 315     }
 316 }
 317
 318 /// A segment of a path: an identifier, an optional lifetime, and a set of
 319 /// types.
 320 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 321 pub struct PathSegment {
 322     /// The identifier portion of this path segment.
 323     pub name: Name,
 324
 325     /// Type/lifetime parameters attached to this path. They come in
 326     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 327     /// this is more than just simple syntactic sugar; the use of
 328     /// parens affects the region binding rules, so we preserve the
 329     /// distinction.
 330     pub parameters: Option<P<PathParameters>>,
 331
 332     /// Whether to infer remaining type parameters, if any.
 333     /// This only applies to expression and pattern paths, and
 334     /// out of those only the segments with no type parameters
 335     /// to begin with, e.g. `Vec::new` is `<Vec<..>>::new::<..>`.
 336     pub infer_types: bool,
 337 }
 338
 339 impl PathSegment {
 340     /// Convert an identifier to the corresponding segment.
 341     pub fn from_name(name: Name) -> PathSegment {
 342         PathSegment {
 343             name,
 344             infer_types: true,
 345             parameters: None
 346         }
 347     }
 348
 349     pub fn new(name: Name, parameters: PathParameters, infer_types: bool) -> Self {
 350         PathSegment {
 351             name,
 352             infer_types,
 353             parameters: if parameters.is_empty() {
 354                 None
 355             } else {
 356                 Some(P(parameters))
 357             }
 358         }
 359     }
 360
 361     // FIXME: hack required because you can't create a static
 362     // PathParameters, so you can't just return a &PathParameters.
 363     pub fn with_parameters<F, R>(&self, f: F) -> R
 364         where F: FnOnce(&PathParameters) -> R
 365     {
 366         let dummy = PathParameters::none();
 367         f(if let Some(ref params) = self.parameters {
 368             &params
 369         } else {
 370             &dummy
 371         })
 372     }
 373 }
 374
 375 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 376 pub struct PathParameters {
 377     /// The lifetime parameters for this path segment.
 378     pub lifetimes: HirVec<Lifetime>,
 379     /// The type parameters for this path segment, if present.
 380     pub types: HirVec<P<Ty>>,
 381     /// Bindings (equality constraints) on associated types, if present.
 382     /// E.g., `Foo<A=Bar>`.
 383     pub bindings: HirVec<TypeBinding>,
 384     /// Were parameters written in parenthesized form `Fn(T) -> U`?
 385     /// This is required mostly for pretty-printing and diagnostics,
 386     /// but also for changing lifetime elision rules to be "function-like".
 387     pub parenthesized: bool,
 388 }
 389
 390 impl PathParameters {
 391     pub fn none() -> Self {
 392         Self {
 393             lifetimes: HirVec::new(),
 394             types: HirVec::new(),
 395             bindings: HirVec::new(),
 396             parenthesized: false,
 397         }
 398     }
 399
 400     pub fn is_empty(&self) -> bool {
 401         self.lifetimes.is_empty() && self.types.is_empty() &&
 402             self.bindings.is_empty() && !self.parenthesized
 403     }
 404
 405     pub fn inputs(&self) -> &[P<Ty>] {
 406         if self.parenthesized {
 407             if let Some(ref ty) = self.types.get(0) {
 408                 if let TyTup(ref tys) = ty.node {
 409                     return tys;
 410                 }
 411             }
 412         }
 413         bug!("PathParameters::inputs: not a `Fn(T) -> U`");
 414     }
 415 }
 416
 417 /// The AST represents all type param bounds as types.
 418 /// typeck::collect::compute_bounds matches these against
 419 /// the "special" built-in traits (see middle::lang_items) and
 420 /// detects Copy, Send and Sync.
 421 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 422 pub enum TyParamBound {
 423     TraitTyParamBound(PolyTraitRef, TraitBoundModifier),
 424     RegionTyParamBound(Lifetime),
 425 }
 426
 427 impl TyParamBound {
 428     pub fn span(&self) -> Span {
 429         match self {
 430             &TraitTyParamBound(ref t, ..) => t.span,
 431             &RegionTyParamBound(ref l) => l.span,
 432         }
 433     }
 434 }
 435
 436 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 437 /// modifier is `Maybe`. Negative bounds should also be handled here.
 438 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 439 pub enum TraitBoundModifier {
 440     None,
 441     Maybe,
 442 }
 443
 444 pub type TyParamBounds = HirVec<TyParamBound>;
 445
 446 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 447 pub struct TyParam {
 448     pub name: Name,
 449     pub id: NodeId,
 450     pub bounds: TyParamBounds,
 451     pub default: Option<P<Ty>>,
 452     pub span: Span,
 453     pub pure_wrt_drop: bool,
 454     pub synthetic: Option<SyntheticTyParamKind>,
 455     pub attrs: HirVec<Attribute>,
 456 }
 457
 458 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 459 pub enum GenericParam {
 460     Lifetime(LifetimeDef),
 461     Type(TyParam),
 462 }
 463
 464 impl GenericParam {
 465     pub fn is_lifetime_param(&self) -> bool {
 466         match *self {
 467             GenericParam::Lifetime(_) => true,
 468             _ => false,
 469         }
 470     }
 471
 472     pub fn is_type_param(&self) -> bool {
 473         match *self {
 474             GenericParam::Type(_) => true,
 475             _ => false,
 476         }
 477     }
 478 }
 479
 480 pub trait GenericParamsExt {
 481     fn lifetimes<'a>(&'a self) -> iter::FilterMap<
 482         slice::Iter<GenericParam>,
 483         fn(&GenericParam) -> Option<&LifetimeDef>,
 484     >;
 485
 486     fn ty_params<'a>(&'a self) -> iter::FilterMap<
 487         slice::Iter<GenericParam>,
 488         fn(&GenericParam) -> Option<&TyParam>,
 489     >;
 490 }
 491
 492 impl GenericParamsExt for [GenericParam] {
 493     fn lifetimes<'a>(&'a self) -> iter::FilterMap<
 494         slice::Iter<GenericParam>,
 495         fn(&GenericParam) -> Option<&LifetimeDef>,
 496     > {
 497         self.iter().filter_map(|param| match *param {
 498             GenericParam::Lifetime(ref l) => Some(l),
 499             _ => None,
 500         })
 501     }
 502
 503     fn ty_params<'a>(&'a self) -> iter::FilterMap<
 504         slice::Iter<GenericParam>,
 505         fn(&GenericParam) -> Option<&TyParam>,
 506     > {
 507         self.iter().filter_map(|param| match *param {
 508             GenericParam::Type(ref t) => Some(t),
 509             _ => None,
 510         })
 511     }
 512 }
 513
 514 /// Represents lifetimes and type parameters attached to a declaration
 515 /// of a function, enum, trait, etc.
 516 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 517 pub struct Generics {
 518     pub params: HirVec<GenericParam>,
 519     pub where_clause: WhereClause,
 520     pub span: Span,
 521 }
 522
 523 impl Generics {
 524     pub fn empty() -> Generics {
 525         Generics {
 526             params: HirVec::new(),
 527             where_clause: WhereClause {
 528                 id: DUMMY_NODE_ID,
 529                 predicates: HirVec::new(),
 530             },
 531             span: DUMMY_SP,
 532         }
 533     }
 534
 535     pub fn is_lt_parameterized(&self) -> bool {
 536         self.params.iter().any(|param| param.is_lifetime_param())
 537     }
 538
 539     pub fn is_type_parameterized(&self) -> bool {
 540         self.params.iter().any(|param| param.is_type_param())
 541     }
 542
 543     pub fn lifetimes<'a>(&'a self) -> impl Iterator<Item = &'a LifetimeDef> {
 544         self.params.lifetimes()
 545     }
 546
 547     pub fn ty_params<'a>(&'a self) -> impl Iterator<Item = &'a TyParam> {
 548         self.params.ty_params()
 549     }
 550 }
 551
 552 pub enum UnsafeGeneric {
 553     Region(LifetimeDef, &'static str),
 554     Type(TyParam, &'static str),
 555 }
 556
 557 impl UnsafeGeneric {
 558     pub fn attr_name(&self) -> &'static str {
 559         match *self {
 560             UnsafeGeneric::Region(_, s) => s,
 561             UnsafeGeneric::Type(_, s) => s,
 562         }
 563     }
 564 }
 565
 566 impl Generics {
 567     pub fn carries_unsafe_attr(&self) -> Option<UnsafeGeneric> {
 568         for param in &self.params {
 569             match *param {
 570                 GenericParam::Lifetime(ref l) => {
 571                     if l.pure_wrt_drop {
 572                         return Some(UnsafeGeneric::Region(l.clone(), "may_dangle"));
 573                     }
 574                 }
 575                 GenericParam::Type(ref t) => {
 576                     if t.pure_wrt_drop {
 577                         return Some(UnsafeGeneric::Type(t.clone(), "may_dangle"));
 578                     }
 579                 }
 580             }
 581         }
 582
 583         None
 584     }
 585 }
 586
 587 /// Synthetic Type Parameters are converted to an other form during lowering, this allows
 588 /// to track the original form they had. Useful for error messages.
 589 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 590 pub enum SyntheticTyParamKind {
 591     ImplTrait
 592 }
 593
 594 /// A `where` clause in a definition
 595 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 596 pub struct WhereClause {
 597     pub id: NodeId,
 598     pub predicates: HirVec<WherePredicate>,
 599 }
 600
 601 impl WhereClause {
 602     pub fn span(&self) -> Option<Span> {
 603         self.predicates.iter().map(|predicate| predicate.span())
 604             .fold(None, |acc, i| match (acc, i) {
 605                 (None, i) => Some(i),
 606                 (Some(acc), i) => {
 607                     Some(acc.to(i))
 608                 }
 609             })
 610     }
 611 }
 612
 613 /// A single predicate in a `where` clause
 614 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 615 pub enum WherePredicate {
 616     /// A type binding, eg `for<'c> Foo: Send+Clone+'c`
 617     BoundPredicate(WhereBoundPredicate),
 618     /// A lifetime predicate, e.g. `'a: 'b+'c`
 619     RegionPredicate(WhereRegionPredicate),
 620     /// An equality predicate (unsupported)
 621     EqPredicate(WhereEqPredicate),
 622 }
 623
 624 impl WherePredicate {
 625     pub fn span(&self) -> Span {
 626         match self {
 627             &WherePredicate::BoundPredicate(ref p) => p.span,
 628             &WherePredicate::RegionPredicate(ref p) => p.span,
 629             &WherePredicate::EqPredicate(ref p) => p.span,
 630         }
 631     }
 632 }
 633
 634 /// A type bound, eg `for<'c> Foo: Send+Clone+'c`
 635 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 636 pub struct WhereBoundPredicate {
 637     pub span: Span,
 638     /// Any generics from a `for` binding
 639     pub bound_generic_params: HirVec<GenericParam>,
 640     /// The type being bounded
 641     pub bounded_ty: P<Ty>,
 642     /// Trait and lifetime bounds (`Clone+Send+'static`)
 643     pub bounds: TyParamBounds,
 644 }
 645
 646 /// A lifetime predicate, e.g. `'a: 'b+'c`
 647 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 648 pub struct WhereRegionPredicate {
 649     pub span: Span,
 650     pub lifetime: Lifetime,
 651     pub bounds: HirVec<Lifetime>,
 652 }
 653
 654 /// An equality predicate (unsupported), e.g. `T=int`
 655 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 656 pub struct WhereEqPredicate {
 657     pub id: NodeId,
 658     pub span: Span,
 659     pub lhs_ty: P<Ty>,
 660     pub rhs_ty: P<Ty>,
 661 }
 662
 663 pub type CrateConfig = HirVec<P<MetaItem>>;
 664
 665 /// The top-level data structure that stores the entire contents of
 666 /// the crate currently being compiled.
 667 ///
 668 /// For more details, see the [rustc guide].
 669 ///
 670 /// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/hir.html
 671 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug)]
 672 pub struct Crate {
 673     pub module: Mod,
 674     pub attrs: HirVec<Attribute>,
 675     pub span: Span,
 676     pub exported_macros: HirVec<MacroDef>,
 677
 678     // NB: We use a BTreeMap here so that `visit_all_items` iterates
 679     // over the ids in increasing order. In principle it should not
 680     // matter what order we visit things in, but in *practice* it
 681     // does, because it can affect the order in which errors are
 682     // detected, which in turn can make compile-fail tests yield
 683     // slightly different results.
 684     pub items: BTreeMap<NodeId, Item>,
 685
 686     pub trait_items: BTreeMap<TraitItemId, TraitItem>,
 687     pub impl_items: BTreeMap<ImplItemId, ImplItem>,
 688     pub bodies: BTreeMap<BodyId, Body>,
 689     pub trait_impls: BTreeMap<DefId, Vec<NodeId>>,
 690     pub trait_auto_impl: BTreeMap<DefId, NodeId>,
 691
 692     /// A list of the body ids written out in the order in which they
 693     /// appear in the crate. If you're going to process all the bodies
 694     /// in the crate, you should iterate over this list rather than the keys
 695     /// of bodies.
 696     pub body_ids: Vec<BodyId>,
 697 }
 698
 699 impl Crate {
 700     pub fn item(&self, id: NodeId) -> &Item {
 701         &self.items[&id]
 702     }
 703
 704     pub fn trait_item(&self, id: TraitItemId) -> &TraitItem {
 705         &self.trait_items[&id]
 706     }
 707
 708     pub fn impl_item(&self, id: ImplItemId) -> &ImplItem {
 709         &self.impl_items[&id]
 710     }
 711
 712     /// Visits all items in the crate in some deterministic (but
 713     /// unspecified) order. If you just need to process every item,
 714     /// but don't care about nesting, this method is the best choice.
 715     ///
 716     /// If you do care about nesting -- usually because your algorithm
 717     /// follows lexical scoping rules -- then you want a different
 718     /// approach. You should override `visit_nested_item` in your
 719     /// visitor and then call `intravisit::walk_crate` instead.
 720     pub fn visit_all_item_likes<'hir, V>(&'hir self, visitor: &mut V)
 721         where V: itemlikevisit::ItemLikeVisitor<'hir>
 722     {
 723         for (_, item) in &self.items {
 724             visitor.visit_item(item);
 725         }
 726
 727         for (_, trait_item) in &self.trait_items {
 728             visitor.visit_trait_item(trait_item);
 729         }
 730
 731         for (_, impl_item) in &self.impl_items {
 732             visitor.visit_impl_item(impl_item);
 733         }
 734     }
 735
 736     /// A parallel version of visit_all_item_likes
 737     pub fn par_visit_all_item_likes<'hir, V>(&'hir self, visitor: &V)
 738         where V: itemlikevisit::ParItemLikeVisitor<'hir> + Sync + Send
 739     {
 740         scope(|s| {
 741             s.spawn(|_| {
 742                 par_iter(&self.items).for_each(|(_, item)| {
 743                     visitor.visit_item(item);
 744                 });
 745             });
 746
 747             s.spawn(|_| {
 748                 par_iter(&self.trait_items).for_each(|(_, trait_item)| {
 749                     visitor.visit_trait_item(trait_item);
 750                 });
 751             });
 752
 753             s.spawn(|_| {
 754                 par_iter(&self.impl_items).for_each(|(_, impl_item)| {
 755                     visitor.visit_impl_item(impl_item);
 756                 });
 757             });
 758         });
 759     }
 760
 761     pub fn body(&self, id: BodyId) -> &Body {
 762         &self.bodies[&id]
 763     }
 764 }
 765
 766 /// A macro definition, in this crate or imported from another.
 767 ///
 768 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
 769 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 770 pub struct MacroDef {
 771     pub name: Name,
 772     pub vis: Visibility,
 773     pub attrs: HirVec<Attribute>,
 774     pub id: NodeId,
 775     pub span: Span,
 776     pub body: TokenStream,
 777     pub legacy: bool,
 778 }
 779
 780 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 781 pub struct Block {
 782     /// Statements in a block
 783     pub stmts: HirVec<Stmt>,
 784     /// An expression at the end of the block
 785     /// without a semicolon, if any
 786     pub expr: Option<P<Expr>>,
 787     pub id: NodeId,
 788     pub hir_id: HirId,
 789     /// Distinguishes between `unsafe { ... }` and `{ ... }`
 790     pub rules: BlockCheckMode,
 791     pub span: Span,
 792     /// If true, then there may exist `break 'a` values that aim to
 793     /// break out of this block early.
 794     /// Used by `'label: {}` blocks and by `catch` statements.
 795     pub targeted_by_break: bool,
 796     /// If true, don't emit return value type errors as the parser had
 797     /// to recover from a parse error so this block will not have an
 798     /// appropriate type. A parse error will have been emitted so the
 799     /// compilation will never succeed if this is true.
 800     pub recovered: bool,
 801 }
 802
 803 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
 804 pub struct Pat {
 805     pub id: NodeId,
 806     pub hir_id: HirId,
 807     pub node: PatKind,
 808     pub span: Span,
 809 }
 810
 811 impl fmt::Debug for Pat {
 812     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 813         write!(f, "pat({}: {})", self.id,
 814                print::to_string(print::NO_ANN, |s| s.print_pat(self)))
 815     }
 816 }
 817
 818 impl Pat {
 819     // FIXME(#19596) this is a workaround, but there should be a better way
 820     fn walk_<G>(&self, it: &mut G) -> bool
 821         where G: FnMut(&Pat) -> bool
 822     {
 823         if !it(self) {
 824             return false;
 825         }
 826
 827         match self.node {
 828             PatKind::Binding(.., Some(ref p)) => p.walk_(it),
 829             PatKind::Struct(_, ref fields, _) => {
 830                 fields.iter().all(|field| field.node.pat.walk_(it))
 831             }
 832             PatKind::TupleStruct(_, ref s, _) | PatKind::Tuple(ref s, _) => {
 833                 s.iter().all(|p| p.walk_(it))
 834             }
 835             PatKind::Box(ref s) | PatKind::Ref(ref s, _) => {
 836                 s.walk_(it)
 837             }
 838             PatKind::Slice(ref before, ref slice, ref after) => {
 839                 before.iter().all(|p| p.walk_(it)) &&
 840                 slice.iter().all(|p| p.walk_(it)) &&
 841                 after.iter().all(|p| p.walk_(it))
 842             }
 843             PatKind::Wild |
 844             PatKind::Lit(_) |
 845             PatKind::Range(..) |
 846             PatKind::Binding(..) |
 847             PatKind::Path(_) => {
 848                 true
 849             }
 850         }
 851     }
 852
 853     pub fn walk<F>(&self, mut it: F) -> bool
 854         where F: FnMut(&Pat) -> bool
 855     {
 856         self.walk_(&mut it)
 857     }
 858 }
 859
 860 /// A single field in a struct pattern
 861 ///
 862 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 863 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 864 /// except is_shorthand is true
 865 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 866 pub struct FieldPat {
 867     pub id: NodeId,
 868     /// The identifier for the field
 869     pub ident: Ident,
 870     /// The pattern the field is destructured to
 871     pub pat: P<Pat>,
 872     pub is_shorthand: bool,
 873 }
 874
 875 /// Explicit binding annotations given in the HIR for a binding. Note
 876 /// that this is not the final binding *mode* that we infer after type
 877 /// inference.
 878 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 879 pub enum BindingAnnotation {
 880   /// No binding annotation given: this means that the final binding mode
 881   /// will depend on whether we have skipped through a `&` reference
 882   /// when matching. For example, the `x` in `Some(x)` will have binding
 883   /// mode `None`; if you do `let Some(x) = &Some(22)`, it will
 884   /// ultimately be inferred to be by-reference.
 885   ///
 886   /// Note that implicit reference skipping is not implemented yet (#42640).
 887   Unannotated,
 888
 889   /// Annotated with `mut x` -- could be either ref or not, similar to `None`.
 890   Mutable,
 891
 892   /// Annotated as `ref`, like `ref x`
 893   Ref,
 894
 895   /// Annotated as `ref mut x`.
 896   RefMut,
 897 }
 898
 899 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 900 pub enum RangeEnd {
 901     Included,
 902     Excluded,
 903 }
 904
 905 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 906 pub enum PatKind {
 907     /// Represents a wildcard pattern (`_`)
 908     Wild,
 909
 910     /// A fresh binding `ref mut binding @ OPT_SUBPATTERN`.
 911     /// The `NodeId` is the canonical ID for the variable being bound,
 912     /// e.g. in `Ok(x) | Err(x)`, both `x` use the same canonical ID,
 913     /// which is the pattern ID of the first `x`.
 914     Binding(BindingAnnotation, NodeId, Spanned<Name>, Option<P<Pat>>),
 915
 916     /// A struct or struct variant pattern, e.g. `Variant {x, y, ..}`.
 917     /// The `bool` is `true` in the presence of a `..`.
 918     Struct(QPath, HirVec<Spanned<FieldPat>>, bool),
 919
 920     /// A tuple struct/variant pattern `Variant(x, y, .., z)`.
 921     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
 922     /// 0 <= position <= subpats.len()
 923     TupleStruct(QPath, HirVec<P<Pat>>, Option<usize>),
 924
 925     /// A path pattern for an unit struct/variant or a (maybe-associated) constant.
 926     Path(QPath),
 927
 928     /// A tuple pattern `(a, b)`.
 929     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
 930     /// 0 <= position <= subpats.len()
 931     Tuple(HirVec<P<Pat>>, Option<usize>),
 932     /// A `box` pattern
 933     Box(P<Pat>),
 934     /// A reference pattern, e.g. `&mut (a, b)`
 935     Ref(P<Pat>, Mutability),
 936     /// A literal
 937     Lit(P<Expr>),
 938     /// A range pattern, e.g. `1...2` or `1..2`
 939     Range(P<Expr>, P<Expr>, RangeEnd),
 940     /// `[a, b, ..i, y, z]` is represented as:
 941     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`
 942     Slice(HirVec<P<Pat>>, Option<P<Pat>>, HirVec<P<Pat>>),
 943 }
 944
 945 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 946 pub enum Mutability {
 947     MutMutable,
 948     MutImmutable,
 949 }
 950
 951 impl Mutability {
 952     /// Return MutMutable only if both arguments are mutable.
 953     pub fn and(self, other: Self) -> Self {
 954         match self {
 955             MutMutable => other,
 956             MutImmutable => MutImmutable,
 957         }
 958     }
 959 }
 960
 961 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 962 pub enum BinOp_ {
 963     /// The `+` operator (addition)
 964     BiAdd,
 965     /// The `-` operator (subtraction)
 966     BiSub,
 967     /// The `*` operator (multiplication)
 968     BiMul,
 969     /// The `/` operator (division)
 970     BiDiv,
 971     /// The `%` operator (modulus)
 972     BiRem,
 973     /// The `&&` operator (logical and)
 974     BiAnd,
 975     /// The `||` operator (logical or)
 976     BiOr,
 977     /// The `^` operator (bitwise xor)
 978     BiBitXor,
 979     /// The `&` operator (bitwise and)
 980     BiBitAnd,
 981     /// The `|` operator (bitwise or)
 982     BiBitOr,
 983     /// The `<<` operator (shift left)
 984     BiShl,
 985     /// The `>>` operator (shift right)
 986     BiShr,
 987     /// The `==` operator (equality)
 988     BiEq,
 989     /// The `<` operator (less than)
 990     BiLt,
 991     /// The `<=` operator (less than or equal to)
 992     BiLe,
 993     /// The `!=` operator (not equal to)
 994     BiNe,
 995     /// The `>=` operator (greater than or equal to)
 996     BiGe,
 997     /// The `>` operator (greater than)
 998     BiGt,
 999 }
1000
1001 impl BinOp_ {
1002     pub fn as_str(self) -> &'static str {
1003         match self {
1004             BiAdd => "+",
1005             BiSub => "-",
1006             BiMul => "*",
1007             BiDiv => "/",
1008             BiRem => "%",
1009             BiAnd => "&&",
1010             BiOr => "||",
1011             BiBitXor => "^",
1012             BiBitAnd => "&",
1013             BiBitOr => "|",
1014             BiShl => "<<",
1015             BiShr => ">>",
1016             BiEq => "==",
1017             BiLt => "<",
1018             BiLe => "<=",
1019             BiNe => "!=",
1020             BiGe => ">=",
1021             BiGt => ">",
1022         }
1023     }
1024
1025     pub fn is_lazy(self) -> bool {
1026         match self {
1027             BiAnd | BiOr => true,
1028             _ => false,
1029         }
1030     }
1031
1032     pub fn is_shift(self) -> bool {
1033         match self {
1034             BiShl | BiShr => true,
1035             _ => false,
1036         }
1037     }
1038
1039     pub fn is_comparison(self) -> bool {
1040         match self {
1041             BiEq | BiLt | BiLe | BiNe | BiGt | BiGe => true,
1042             BiAnd |
1043             BiOr |
1044             BiAdd |
1045             BiSub |
1046             BiMul |
1047             BiDiv |
1048             BiRem |
1049             BiBitXor |
1050             BiBitAnd |
1051             BiBitOr |
1052             BiShl |
1053             BiShr => false,
1054         }
1055     }
1056
1057     /// Returns `true` if the binary operator takes its arguments by value
1058     pub fn is_by_value(self) -> bool {
1059         !self.is_comparison()
1060     }
1061 }
1062
1063 impl Into<ast::BinOpKind> for BinOp_ {
1064     fn into(self) -> ast::BinOpKind {
1065         match self {
1066             BiAdd => ast::BinOpKind::Add,
1067             BiSub => ast::BinOpKind::Sub,
1068             BiMul => ast::BinOpKind::Mul,
1069             BiDiv => ast::BinOpKind::Div,
1070             BiRem => ast::BinOpKind::Rem,
1071             BiAnd => ast::BinOpKind::And,
1072             BiOr => ast::BinOpKind::Or,
1073             BiBitXor => ast::BinOpKind::BitXor,
1074             BiBitAnd => ast::BinOpKind::BitAnd,
1075             BiBitOr => ast::BinOpKind::BitOr,
1076             BiShl => ast::BinOpKind::Shl,
1077             BiShr => ast::BinOpKind::Shr,
1078             BiEq => ast::BinOpKind::Eq,
1079             BiLt => ast::BinOpKind::Lt,
1080             BiLe => ast::BinOpKind::Le,
1081             BiNe => ast::BinOpKind::Ne,
1082             BiGe => ast::BinOpKind::Ge,
1083             BiGt => ast::BinOpKind::Gt,
1084         }
1085     }
1086 }
1087
1088 pub type BinOp = Spanned<BinOp_>;
1089
1090 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1091 pub enum UnOp {
1092     /// The `*` operator for dereferencing
1093     UnDeref,
1094     /// The `!` operator for logical inversion
1095     UnNot,
1096     /// The `-` operator for negation
1097     UnNeg,
1098 }
1099
1100 impl UnOp {
1101     pub fn as_str(self) -> &'static str {
1102         match self {
1103             UnDeref => "*",
1104             UnNot => "!",
1105             UnNeg => "-",
1106         }
1107     }
1108
1109     /// Returns `true` if the unary operator takes its argument by value
1110     pub fn is_by_value(self) -> bool {
1111         match self {
1112             UnNeg | UnNot => true,
1113             _ => false,
1114         }
1115     }
1116 }
1117
1118 /// A statement
1119 pub type Stmt = Spanned<Stmt_>;
1120
1121 impl fmt::Debug for Stmt_ {
1122     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1123         // Sadness.
1124         let spanned = codemap::dummy_spanned(self.clone());
1125         write!(f,
1126                "stmt({}: {})",
1127                spanned.node.id(),
1128                print::to_string(print::NO_ANN, |s| s.print_stmt(&spanned)))
1129     }
1130 }
1131
1132 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1133 pub enum Stmt_ {
1134     /// Could be an item or a local (let) binding:
1135     StmtDecl(P<Decl>, NodeId),
1136
1137     /// Expr without trailing semi-colon (must have unit type):
1138     StmtExpr(P<Expr>, NodeId),
1139
1140     /// Expr with trailing semi-colon (may have any type):
1141     StmtSemi(P<Expr>, NodeId),
1142 }
1143
1144 impl Stmt_ {
1145     pub fn attrs(&self) -> &[Attribute] {
1146         match *self {
1147             StmtDecl(ref d, _) => d.node.attrs(),
1148             StmtExpr(ref e, _) |
1149             StmtSemi(ref e, _) => &e.attrs,
1150         }
1151     }
1152
1153     pub fn id(&self) -> NodeId {
1154         match *self {
1155             StmtDecl(_, id) => id,
1156             StmtExpr(_, id) => id,
1157             StmtSemi(_, id) => id,
1158         }
1159     }
1160 }
1161
1162 /// Local represents a `let` statement, e.g., `let <pat>:<ty> = <expr>;`
1163 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1164 pub struct Local {
1165     pub pat: P<Pat>,
1166     pub ty: Option<P<Ty>>,
1167     /// Initializer expression to set the value, if any
1168     pub init: Option<P<Expr>>,
1169     pub id: NodeId,
1170     pub hir_id: HirId,
1171     pub span: Span,
1172     pub attrs: ThinVec<Attribute>,
1173     pub source: LocalSource,
1174 }
1175
1176 pub type Decl = Spanned<Decl_>;
1177
1178 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1179 pub enum Decl_ {
1180     /// A local (let) binding:
1181     DeclLocal(P<Local>),
1182     /// An item binding:
1183     DeclItem(ItemId),
1184 }
1185
1186 impl Decl_ {
1187     pub fn attrs(&self) -> &[Attribute] {
1188         match *self {
1189             DeclLocal(ref l) => &l.attrs,
1190             DeclItem(_) => &[]
1191         }
1192     }
1193
1194     pub fn is_local(&self) -> bool {
1195         match *self {
1196             Decl_::DeclLocal(_) => true,
1197             _ => false,
1198         }
1199     }
1200 }
1201
1202 /// represents one arm of a 'match'
1203 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1204 pub struct Arm {
1205     pub attrs: HirVec<Attribute>,
1206     pub pats: HirVec<P<Pat>>,
1207     pub guard: Option<P<Expr>>,
1208     pub body: P<Expr>,
1209 }
1210
1211 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1212 pub struct Field {
1213     pub id: NodeId,
1214     pub ident: Ident,
1215     pub expr: P<Expr>,
1216     pub span: Span,
1217     pub is_shorthand: bool,
1218 }
1219
1220 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1221 pub enum BlockCheckMode {
1222     DefaultBlock,
1223     UnsafeBlock(UnsafeSource),
1224     PushUnsafeBlock(UnsafeSource),
1225     PopUnsafeBlock(UnsafeSource),
1226 }
1227
1228 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1229 pub enum UnsafeSource {
1230     CompilerGenerated,
1231     UserProvided,
1232 }
1233
1234 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
1235 pub struct BodyId {
1236     pub node_id: NodeId,
1237 }
1238
1239 /// The body of a function, closure, or constant value. In the case of
1240 /// a function, the body contains not only the function body itself
1241 /// (which is an expression), but also the argument patterns, since
1242 /// those are something that the caller doesn't really care about.
1243 ///
1244 /// # Examples
1245 ///
1246 /// ```
1247 /// fn foo((x, y): (u32, u32)) -> u32 {
1248 ///     x + y
1249 /// }
1250 /// ```
1251 ///
1252 /// Here, the `Body` associated with `foo()` would contain:
1253 ///
1254 /// - an `arguments` array containing the `(x, y)` pattern
1255 /// - a `value` containing the `x + y` expression (maybe wrapped in a block)
1256 /// - `is_generator` would be false
1257 ///
1258 /// All bodies have an **owner**, which can be accessed via the HIR
1259 /// map using `body_owner_def_id()`.
1260 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1261 pub struct Body {
1262     pub arguments: HirVec<Arg>,
1263     pub value: Expr,
1264     pub is_generator: bool,
1265 }
1266
1267 impl Body {
1268     pub fn id(&self) -> BodyId {
1269         BodyId {
1270             node_id: self.value.id
1271         }
1272     }
1273 }
1274
1275 #[derive(Copy, Clone, Debug)]
1276 pub enum BodyOwnerKind {
1277     /// Functions and methods.
1278     Fn,
1279
1280     /// Constants and associated constants.
1281     Const,
1282
1283     /// Initializer of a `static` item.
1284     Static(Mutability),
1285 }
1286
1287 /// A constant (expression) that's not an item or associated item,
1288 /// but needs its own `DefId` for type-checking, const-eval, etc.
1289 /// These are usually found nested inside types (e.g. array lengths)
1290 /// or expressions (e.g. repeat counts), and also used to define
1291 /// explicit discriminant values for enum variants.
1292 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1293 pub struct AnonConst {
1294     pub id: NodeId,
1295     pub hir_id: HirId,
1296     pub body: BodyId,
1297 }
1298
1299 /// An expression
1300 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1301 pub struct Expr {
1302     pub id: NodeId,
1303     pub span: Span,
1304     pub node: Expr_,
1305     pub attrs: ThinVec<Attribute>,
1306     pub hir_id: HirId,
1307 }
1308
1309 impl Expr {
1310     pub fn precedence(&self) -> ExprPrecedence {
1311         match self.node {
1312             ExprBox(_) => ExprPrecedence::Box,
1313             ExprArray(_) => ExprPrecedence::Array,
1314             ExprCall(..) => ExprPrecedence::Call,
1315             ExprMethodCall(..) => ExprPrecedence::MethodCall,
1316             ExprTup(_) => ExprPrecedence::Tup,
1317             ExprBinary(op, ..) => ExprPrecedence::Binary(op.node.into()),
1318             ExprUnary(..) => ExprPrecedence::Unary,
1319             ExprLit(_) => ExprPrecedence::Lit,
1320             ExprType(..) | ExprCast(..) => ExprPrecedence::Cast,
1321             ExprIf(..) => ExprPrecedence::If,
1322             ExprWhile(..) => ExprPrecedence::While,
1323             ExprLoop(..) => ExprPrecedence::Loop,
1324             ExprMatch(..) => ExprPrecedence::Match,
1325             ExprClosure(..) => ExprPrecedence::Closure,
1326             ExprBlock(..) => ExprPrecedence::Block,
1327             ExprAssign(..) => ExprPrecedence::Assign,
1328             ExprAssignOp(..) => ExprPrecedence::AssignOp,
1329             ExprField(..) => ExprPrecedence::Field,
1330             ExprIndex(..) => ExprPrecedence::Index,
1331             ExprPath(..) => ExprPrecedence::Path,
1332             ExprAddrOf(..) => ExprPrecedence::AddrOf,
1333             ExprBreak(..) => ExprPrecedence::Break,
1334             ExprAgain(..) => ExprPrecedence::Continue,
1335             ExprRet(..) => ExprPrecedence::Ret,
1336             ExprInlineAsm(..) => ExprPrecedence::InlineAsm,
1337             ExprStruct(..) => ExprPrecedence::Struct,
1338             ExprRepeat(..) => ExprPrecedence::Repeat,
1339             ExprYield(..) => ExprPrecedence::Yield,
1340         }
1341     }
1342 }
1343
1344 impl fmt::Debug for Expr {
1345     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1346         write!(f, "expr({}: {})", self.id,
1347                print::to_string(print::NO_ANN, |s| s.print_expr(self)))
1348     }
1349 }
1350
1351 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1352 pub enum Expr_ {
1353     /// A `box x` expression.
1354     ExprBox(P<Expr>),
1355     /// An array (`[a, b, c, d]`)
1356     ExprArray(HirVec<Expr>),
1357     /// A function call
1358     ///
1359     /// The first field resolves to the function itself (usually an `ExprPath`),
1360     /// and the second field is the list of arguments.
1361     /// This also represents calling the constructor of
1362     /// tuple-like ADTs such as tuple structs and enum variants.
1363     ExprCall(P<Expr>, HirVec<Expr>),
1364     /// A method call (`x.foo::<'static, Bar, Baz>(a, b, c, d)`)
1365     ///
1366     /// The `PathSegment`/`Span` represent the method name and its generic arguments
1367     /// (within the angle brackets).
1368     /// The first element of the vector of `Expr`s is the expression that evaluates
1369     /// to the object on which the method is being called on (the receiver),
1370     /// and the remaining elements are the rest of the arguments.
1371     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
1372     /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
1373     ExprMethodCall(PathSegment, Span, HirVec<Expr>),
1374     /// A tuple (`(a, b, c ,d)`)
1375     ExprTup(HirVec<Expr>),
1376     /// A binary operation (For example: `a + b`, `a * b`)
1377     ExprBinary(BinOp, P<Expr>, P<Expr>),
1378     /// A unary operation (For example: `!x`, `*x`)
1379     ExprUnary(UnOp, P<Expr>),
1380     /// A literal (For example: `1`, `"foo"`)
1381     ExprLit(P<Lit>),
1382     /// A cast (`foo as f64`)
1383     ExprCast(P<Expr>, P<Ty>),
1384     ExprType(P<Expr>, P<Ty>),
1385     /// An `if` block, with an optional else block
1386     ///
1387     /// `if expr { expr } else { expr }`
1388     ExprIf(P<Expr>, P<Expr>, Option<P<Expr>>),
1389     /// A while loop, with an optional label
1390     ///
1391     /// `'label: while expr { block }`
1392     ExprWhile(P<Expr>, P<Block>, Option<Label>),
1393     /// Conditionless loop (can be exited with break, continue, or return)
1394     ///
1395     /// `'label: loop { block }`
1396     ExprLoop(P<Block>, Option<Label>, LoopSource),
1397     /// A `match` block, with a source that indicates whether or not it is
1398     /// the result of a desugaring, and if so, which kind.
1399     ExprMatch(P<Expr>, HirVec<Arm>, MatchSource),
1400     /// A closure (for example, `move |a, b, c| {a + b + c}`).
1401     ///
1402     /// The final span is the span of the argument block `|...|`
1403     ///
1404     /// This may also be a generator literal, indicated by the final boolean,
1405     /// in that case there is an GeneratorClause.
1406     ExprClosure(CaptureClause, P<FnDecl>, BodyId, Span, Option<GeneratorMovability>),
1407     /// A block (`'label: { ... }`)
1408     ExprBlock(P<Block>, Option<Label>),
1409
1410     /// An assignment (`a = foo()`)
1411     ExprAssign(P<Expr>, P<Expr>),
1412     /// An assignment with an operator
1413     ///
1414     /// For example, `a += 1`.
1415     ExprAssignOp(BinOp, P<Expr>, P<Expr>),
1416     /// Access of a named (`obj.foo`) or unnamed (`obj.0`) struct or tuple field
1417     ExprField(P<Expr>, Ident),
1418     /// An indexing operation (`foo[2]`)
1419     ExprIndex(P<Expr>, P<Expr>),
1420
1421     /// Path to a definition, possibly containing lifetime or type parameters.
1422     ExprPath(QPath),
1423
1424     /// A referencing operation (`&a` or `&mut a`)
1425     ExprAddrOf(Mutability, P<Expr>),
1426     /// A `break`, with an optional label to break
1427     ExprBreak(Destination, Option<P<Expr>>),
1428     /// A `continue`, with an optional label
1429     ExprAgain(Destination),
1430     /// A `return`, with an optional value to be returned
1431     ExprRet(Option<P<Expr>>),
1432
1433     /// Inline assembly (from `asm!`), with its outputs and inputs.
1434     ExprInlineAsm(P<InlineAsm>, HirVec<Expr>, HirVec<Expr>),
1435
1436     /// A struct or struct-like variant literal expression.
1437     ///
1438     /// For example, `Foo {x: 1, y: 2}`, or
1439     /// `Foo {x: 1, .. base}`, where `base` is the `Option<Expr>`.
1440     ExprStruct(QPath, HirVec<Field>, Option<P<Expr>>),
1441
1442     /// An array literal constructed from one repeated element.
1443     ///
1444     /// For example, `[1; 5]`. The first expression is the element
1445     /// to be repeated; the second is the number of times to repeat it.
1446     ExprRepeat(P<Expr>, AnonConst),
1447
1448     /// A suspension point for generators. This is `yield <expr>` in Rust.
1449     ExprYield(P<Expr>),
1450 }
1451
1452 /// Optionally `Self`-qualified value/type path or associated extension.
1453 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1454 pub enum QPath {
1455     /// Path to a definition, optionally "fully-qualified" with a `Self`
1456     /// type, if the path points to an associated item in a trait.
1457     ///
1458     /// E.g. an unqualified path like `Clone::clone` has `None` for `Self`,
1459     /// while `<Vec<T> as Clone>::clone` has `Some(Vec<T>)` for `Self`,
1460     /// even though they both have the same two-segment `Clone::clone` `Path`.
1461     Resolved(Option<P<Ty>>, P<Path>),
1462
1463     /// Type-related paths, e.g. `<T>::default` or `<T>::Output`.
1464     /// Will be resolved by type-checking to an associated item.
1465     ///
1466     /// UFCS source paths can desugar into this, with `Vec::new` turning into
1467     /// `<Vec>::new`, and `T::X::Y::method` into `<<<T>::X>::Y>::method`,
1468     /// the `X` and `Y` nodes each being a `TyPath(QPath::TypeRelative(..))`.
1469     TypeRelative(P<Ty>, P<PathSegment>)
1470 }
1471
1472 /// Hints at the original code for a let statement
1473 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1474 pub enum LocalSource {
1475     /// A `match _ { .. }`
1476     Normal,
1477     /// A desugared `for _ in _ { .. }` loop
1478     ForLoopDesugar,
1479 }
1480
1481 /// Hints at the original code for a `match _ { .. }`
1482 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1483 pub enum MatchSource {
1484     /// A `match _ { .. }`
1485     Normal,
1486     /// An `if let _ = _ { .. }` (optionally with `else { .. }`)
1487     IfLetDesugar {
1488         contains_else_clause: bool,
1489     },
1490     /// A `while let _ = _ { .. }` (which was desugared to a
1491     /// `loop { match _ { .. } }`)
1492     WhileLetDesugar,
1493     /// A desugared `for _ in _ { .. }` loop
1494     ForLoopDesugar,
1495     /// A desugared `?` operator
1496     TryDesugar,
1497 }
1498
1499 /// The loop type that yielded an ExprLoop
1500 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1501 pub enum LoopSource {
1502     /// A `loop { .. }` loop
1503     Loop,
1504     /// A `while let _ = _ { .. }` loop
1505     WhileLet,
1506     /// A `for _ in _ { .. }` loop
1507     ForLoop,
1508 }
1509
1510 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1511 pub enum LoopIdError {
1512     OutsideLoopScope,
1513     UnlabeledCfInWhileCondition,
1514     UnresolvedLabel,
1515 }
1516
1517 impl fmt::Display for LoopIdError {
1518     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1519         fmt::Display::fmt(match *self {
1520             LoopIdError::OutsideLoopScope => "not inside loop scope",
1521             LoopIdError::UnlabeledCfInWhileCondition =>
1522                 "unlabeled control flow (break or continue) in while condition",
1523             LoopIdError::UnresolvedLabel => "label not found",
1524         }, f)
1525     }
1526 }
1527
1528 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1529 pub struct Destination {
1530     // This is `Some(_)` iff there is an explicit user-specified `label
1531     pub label: Option<Label>,
1532
1533     // These errors are caught and then reported during the diagnostics pass in
1534     // librustc_passes/loops.rs
1535     pub target_id: Result<NodeId, LoopIdError>,
1536 }
1537
1538 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1539 pub enum GeneratorMovability {
1540     Static,
1541     Movable,
1542 }
1543
1544 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1545 pub enum CaptureClause {
1546     CaptureByValue,
1547     CaptureByRef,
1548 }
1549
1550 // NB: If you change this, you'll probably want to change the corresponding
1551 // type structure in middle/ty.rs as well.
1552 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1553 pub struct MutTy {
1554     pub ty: P<Ty>,
1555     pub mutbl: Mutability,
1556 }
1557
1558 /// Represents a method's signature in a trait declaration or implementation.
1559 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1560 pub struct MethodSig {
1561     pub unsafety: Unsafety,
1562     pub constness: Constness,
1563     pub abi: Abi,
1564     pub decl: P<FnDecl>,
1565 }
1566
1567 // The bodies for items are stored "out of line", in a separate
1568 // hashmap in the `Crate`. Here we just record the node-id of the item
1569 // so it can fetched later.
1570 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
1571 pub struct TraitItemId {
1572     pub node_id: NodeId,
1573 }
1574
1575 /// Represents an item declaration within a trait declaration,
1576 /// possibly including a default implementation. A trait item is
1577 /// either required (meaning it doesn't have an implementation, just a
1578 /// signature) or provided (meaning it has a default implementation).
1579 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1580 pub struct TraitItem {
1581     pub id: NodeId,
1582     pub name: Name,
1583     pub hir_id: HirId,
1584     pub attrs: HirVec<Attribute>,
1585     pub generics: Generics,
1586     pub node: TraitItemKind,
1587     pub span: Span,
1588 }
1589
1590 /// A trait method's body (or just argument names).
1591 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1592 pub enum TraitMethod {
1593     /// No default body in the trait, just a signature.
1594     Required(HirVec<Spanned<Name>>),
1595
1596     /// Both signature and body are provided in the trait.
1597     Provided(BodyId),
1598 }
1599
1600 /// Represents a trait method or associated constant or type
1601 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1602 pub enum TraitItemKind {
1603     /// An associated constant with an optional value (otherwise `impl`s
1604     /// must contain a value)
1605     Const(P<Ty>, Option<BodyId>),
1606     /// A method with an optional body
1607     Method(MethodSig, TraitMethod),
1608     /// An associated type with (possibly empty) bounds and optional concrete
1609     /// type
1610     Type(TyParamBounds, Option<P<Ty>>),
1611 }
1612
1613 // The bodies for items are stored "out of line", in a separate
1614 // hashmap in the `Crate`. Here we just record the node-id of the item
1615 // so it can fetched later.
1616 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
1617 pub struct ImplItemId {
1618     pub node_id: NodeId,
1619 }
1620
1621 /// Represents anything within an `impl` block
1622 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1623 pub struct ImplItem {
1624     pub id: NodeId,
1625     pub name: Name,
1626     pub hir_id: HirId,
1627     pub vis: Visibility,
1628     pub defaultness: Defaultness,
1629     pub attrs: HirVec<Attribute>,
1630     pub generics: Generics,
1631     pub node: ImplItemKind,
1632     pub span: Span,
1633 }
1634
1635 /// Represents different contents within `impl`s
1636 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1637 pub enum ImplItemKind {
1638     /// An associated constant of the given type, set to the constant result
1639     /// of the expression
1640     Const(P<Ty>, BodyId),
1641     /// A method implementation with the given signature and body
1642     Method(MethodSig, BodyId),
1643     /// An associated type
1644     Type(P<Ty>),
1645 }
1646
1647 // Bind a type to an associated type: `A=Foo`.
1648 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1649 pub struct TypeBinding {
1650     pub id: NodeId,
1651     pub name: Name,
1652     pub ty: P<Ty>,
1653     pub span: Span,
1654 }
1655
1656
1657 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1658 pub struct Ty {
1659     pub id: NodeId,
1660     pub node: Ty_,
1661     pub span: Span,
1662     pub hir_id: HirId,
1663 }
1664
1665 impl fmt::Debug for Ty {
1666     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1667         write!(f, "type({})",
1668                print::to_string(print::NO_ANN, |s| s.print_type(self)))
1669     }
1670 }
1671
1672 /// Not represented directly in the AST, referred to by name through a ty_path.
1673 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
1674 pub enum PrimTy {
1675     TyInt(IntTy),
1676     TyUint(UintTy),
1677     TyFloat(FloatTy),
1678     TyStr,
1679     TyBool,
1680     TyChar,
1681 }
1682
1683 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1684 pub struct BareFnTy {
1685     pub unsafety: Unsafety,
1686     pub abi: Abi,
1687     pub generic_params: HirVec<GenericParam>,
1688     pub decl: P<FnDecl>,
1689     pub arg_names: HirVec<Spanned<Name>>,
1690 }
1691
1692 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1693 pub struct ExistTy {
1694     pub generics: Generics,
1695     pub bounds: TyParamBounds,
1696     pub impl_trait_fn: Option<DefId>,
1697 }
1698
1699 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1700 /// The different kinds of types recognized by the compiler
1701 pub enum Ty_ {
1702     /// A variable length slice (`[T]`)
1703     TySlice(P<Ty>),
1704     /// A fixed length array (`[T; n]`)
1705     TyArray(P<Ty>, AnonConst),
1706     /// A raw pointer (`*const T` or `*mut T`)
1707     TyPtr(MutTy),
1708     /// A reference (`&'a T` or `&'a mut T`)
1709     TyRptr(Lifetime, MutTy),
1710     /// A bare function (e.g. `fn(usize) -> bool`)
1711     TyBareFn(P<BareFnTy>),
1712     /// The never type (`!`)
1713     TyNever,
1714     /// A tuple (`(A, B, C, D,...)`)
1715     TyTup(HirVec<P<Ty>>),
1716     /// A path to a type definition (`module::module::...::Type`), or an
1717     /// associated type, e.g. `<Vec<T> as Trait>::Type` or `<T>::Target`.
1718     ///
1719     /// Type parameters may be stored in each `PathSegment`.
1720     TyPath(QPath),
1721     /// A trait object type `Bound1 + Bound2 + Bound3`
1722     /// where `Bound` is a trait or a lifetime.
1723     TyTraitObject(HirVec<PolyTraitRef>, Lifetime),
1724     /// An existentially quantified (there exists a type satisfying) `impl
1725     /// Bound1 + Bound2 + Bound3` type where `Bound` is a trait or a lifetime.
1726     ///
1727     /// The `Item` is the generated
1728     /// `existential type Foo<'a, 'b>: MyTrait<'a, 'b>;`.
1729     ///
1730     /// The `HirVec<Lifetime>` is the list of lifetimes applied as parameters
1731     /// to the `abstract type`, e.g. the `'c` and `'d` in `-> Foo<'c, 'd>`.
1732     /// This list is only a list of lifetimes and not type parameters
1733     /// because all in-scope type parameters are captured by `impl Trait`,
1734     /// so they are resolved directly through the parent `Generics`.
1735     TyImplTraitExistential(ItemId, DefId, HirVec<Lifetime>),
1736     /// Unused for now
1737     TyTypeof(AnonConst),
1738     /// TyInfer means the type should be inferred instead of it having been
1739     /// specified. This can appear anywhere in a type.
1740     TyInfer,
1741     /// Placeholder for a type that has failed to be defined.
1742     TyErr,
1743 }
1744
1745 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1746 pub struct InlineAsmOutput {
1747     pub constraint: Symbol,
1748     pub is_rw: bool,
1749     pub is_indirect: bool,
1750 }
1751
1752 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1753 pub struct InlineAsm {
1754     pub asm: Symbol,
1755     pub asm_str_style: StrStyle,
1756     pub outputs: HirVec<InlineAsmOutput>,
1757     pub inputs: HirVec<Symbol>,
1758     pub clobbers: HirVec<Symbol>,
1759     pub volatile: bool,
1760     pub alignstack: bool,
1761     pub dialect: AsmDialect,
1762     pub ctxt: SyntaxContext,
1763 }
1764
1765 /// represents an argument in a function header
1766 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1767 pub struct Arg {
1768     pub pat: P<Pat>,
1769     pub id: NodeId,
1770     pub hir_id: HirId,
1771 }
1772
1773 /// Represents the header (not the body) of a function declaration
1774 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1775 pub struct FnDecl {
1776     pub inputs: HirVec<P<Ty>>,
1777     pub output: FunctionRetTy,
1778     pub variadic: bool,
1779     /// True if this function has an `self`, `&self` or `&mut self` receiver
1780     /// (but not a `self: Xxx` one).
1781     pub has_implicit_self: bool,
1782 }
1783
1784 /// Is the trait definition an auto trait?
1785 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1786 pub enum IsAuto {
1787     Yes,
1788     No
1789 }
1790
1791 #[derive(Copy, Clone, PartialEq, Eq,PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
1792 pub enum Unsafety {
1793     Unsafe,
1794     Normal,
1795 }
1796
1797 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1798 pub enum Constness {
1799     Const,
1800     NotConst,
1801 }
1802
1803 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1804 pub enum Defaultness {
1805     Default { has_value: bool },
1806     Final,
1807 }
1808
1809 impl Defaultness {
1810     pub fn has_value(&self) -> bool {
1811         match *self {
1812             Defaultness::Default { has_value, .. } => has_value,
1813             Defaultness::Final => true,
1814         }
1815     }
1816
1817     pub fn is_final(&self) -> bool {
1818         *self == Defaultness::Final
1819     }
1820
1821     pub fn is_default(&self) -> bool {
1822         match *self {
1823             Defaultness::Default { .. } => true,
1824             _ => false,
1825         }
1826     }
1827 }
1828
1829 impl fmt::Display for Unsafety {
1830     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1831         fmt::Display::fmt(match *self {
1832                               Unsafety::Normal => "normal",
1833                               Unsafety::Unsafe => "unsafe",
1834                           },
1835                           f)
1836     }
1837 }
1838
1839 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash)]
1840 pub enum ImplPolarity {
1841     /// `impl Trait for Type`
1842     Positive,
1843     /// `impl !Trait for Type`
1844     Negative,
1845 }
1846
1847 impl fmt::Debug for ImplPolarity {
1848     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1849         match *self {
1850             ImplPolarity::Positive => "positive".fmt(f),
1851             ImplPolarity::Negative => "negative".fmt(f),
1852         }
1853     }
1854 }
1855
1856
1857 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1858 pub enum FunctionRetTy {
1859     /// Return type is not specified.
1860     ///
1861     /// Functions default to `()` and
1862     /// closures default to inference. Span points to where return
1863     /// type would be inserted.
1864     DefaultReturn(Span),
1865     /// Everything else
1866     Return(P<Ty>),
1867 }
1868
1869 impl FunctionRetTy {
1870     pub fn span(&self) -> Span {
1871         match *self {
1872             DefaultReturn(span) => span,
1873             Return(ref ty) => ty.span,
1874         }
1875     }
1876 }
1877
1878 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1879 pub struct Mod {
1880     /// A span from the first token past `{` to the last token until `}`.
1881     /// For `mod foo;`, the inner span ranges from the first token
1882     /// to the last token in the external file.
1883     pub inner: Span,
1884     pub item_ids: HirVec<ItemId>,
1885 }
1886
1887 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1888 pub struct ForeignMod {
1889     pub abi: Abi,
1890     pub items: HirVec<ForeignItem>,
1891 }
1892
1893 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1894 pub struct GlobalAsm {
1895     pub asm: Symbol,
1896     pub ctxt: SyntaxContext,
1897 }
1898
1899 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1900 pub struct EnumDef {
1901     pub variants: HirVec<Variant>,
1902 }
1903
1904 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1905 pub struct Variant_ {
1906     pub name: Name,
1907     pub attrs: HirVec<Attribute>,
1908     pub data: VariantData,
1909     /// Explicit discriminant, eg `Foo = 1`
1910     pub disr_expr: Option<AnonConst>,
1911 }
1912
1913 pub type Variant = Spanned<Variant_>;
1914
1915 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1916 pub enum UseKind {
1917     /// One import, e.g. `use foo::bar` or `use foo::bar as baz`.
1918     /// Also produced for each element of a list `use`, e.g.
1919     // `use foo::{a, b}` lowers to `use foo::a; use foo::b;`.
1920     Single,
1921
1922     /// Glob import, e.g. `use foo::*`.
1923     Glob,
1924
1925     /// Degenerate list import, e.g. `use foo::{a, b}` produces
1926     /// an additional `use foo::{}` for performing checks such as
1927     /// unstable feature gating. May be removed in the future.
1928     ListStem,
1929 }
1930
1931 /// TraitRef's appear in impls.
1932 ///
1933 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
1934 /// that the ref_id is for. Note that ref_id's value is not the NodeId of the
1935 /// trait being referred to but just a unique NodeId that serves as a key
1936 /// within the DefMap.
1937 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1938 pub struct TraitRef {
1939     pub path: Path,
1940     pub ref_id: NodeId,
1941 }
1942
1943 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1944 pub struct PolyTraitRef {
1945     /// The `'a` in `<'a> Foo<&'a T>`
1946     pub bound_generic_params: HirVec<GenericParam>,
1947
1948     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`
1949     pub trait_ref: TraitRef,
1950
1951     pub span: Span,
1952 }
1953
1954 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1955 pub enum Visibility {
1956     Public,
1957     Crate(CrateSugar),
1958     Restricted { path: P<Path>, id: NodeId },
1959     Inherited,
1960 }
1961
1962 impl Visibility {
1963     pub fn is_pub_restricted(&self) -> bool {
1964         use self::Visibility::*;
1965         match self {
1966             &Public |
1967             &Inherited => false,
1968             &Crate(_) |
1969             &Restricted { .. } => true,
1970         }
1971     }
1972 }
1973
1974 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
1975 pub struct StructField {
1976     pub span: Span,
1977     pub ident: Ident,
1978     pub vis: Visibility,
1979     pub id: NodeId,
1980     pub ty: P<Ty>,
1981     pub attrs: HirVec<Attribute>,
1982 }
1983
1984 impl StructField {
1985     // Still necessary in couple of places
1986     pub fn is_positional(&self) -> bool {
1987         let first = self.ident.as_str().as_bytes()[0];
1988         first >= b'0' && first <= b'9'
1989     }
1990 }
1991
1992 /// Fields and Ids of enum variants and structs
1993 ///
1994 /// For enum variants: `NodeId` represents both an Id of the variant itself (relevant for all
1995 /// variant kinds) and an Id of the variant's constructor (not relevant for `Struct`-variants).
1996 /// One shared Id can be successfully used for these two purposes.
1997 /// Id of the whole enum lives in `Item`.
1998 ///
1999 /// For structs: `NodeId` represents an Id of the structure's constructor, so it is not actually
2000 /// used for `Struct`-structs (but still presents). Structures don't have an analogue of "Id of
2001 /// the variant itself" from enum variants.
2002 /// Id of the whole struct lives in `Item`.
2003 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2004 pub enum VariantData {
2005     Struct(HirVec<StructField>, NodeId),
2006     Tuple(HirVec<StructField>, NodeId),
2007     Unit(NodeId),
2008 }
2009
2010 impl VariantData {
2011     pub fn fields(&self) -> &[StructField] {
2012         match *self {
2013             VariantData::Struct(ref fields, _) | VariantData::Tuple(ref fields, _) => fields,
2014             _ => &[],
2015         }
2016     }
2017     pub fn id(&self) -> NodeId {
2018         match *self {
2019             VariantData::Struct(_, id) | VariantData::Tuple(_, id) | VariantData::Unit(id) => id,
2020         }
2021     }
2022     pub fn is_struct(&self) -> bool {
2023         if let VariantData::Struct(..) = *self {
2024             true
2025         } else {
2026             false
2027         }
2028     }
2029     pub fn is_tuple(&self) -> bool {
2030         if let VariantData::Tuple(..) = *self {
2031             true
2032         } else {
2033             false
2034         }
2035     }
2036     pub fn is_unit(&self) -> bool {
2037         if let VariantData::Unit(..) = *self {
2038             true
2039         } else {
2040             false
2041         }
2042     }
2043 }
2044
2045 // The bodies for items are stored "out of line", in a separate
2046 // hashmap in the `Crate`. Here we just record the node-id of the item
2047 // so it can fetched later.
2048 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2049 pub struct ItemId {
2050     pub id: NodeId,
2051 }
2052
2053 /// An item
2054 ///
2055 /// The name might be a dummy name in case of anonymous items
2056 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2057 pub struct Item {
2058     pub name: Name,
2059     pub id: NodeId,
2060     pub hir_id: HirId,
2061     pub attrs: HirVec<Attribute>,
2062     pub node: Item_,
2063     pub vis: Visibility,
2064     pub span: Span,
2065 }
2066
2067 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2068 pub enum Item_ {
2069     /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
2070     ///
2071     /// E.g. `extern crate foo` or `extern crate foo_bar as foo`
2072     ItemExternCrate(Option<Name>),
2073
2074     /// `use foo::bar::*;` or `use foo::bar::baz as quux;`
2075     ///
2076     /// or just
2077     ///
2078     /// `use foo::bar::baz;` (with `as baz` implicitly on the right)
2079     ItemUse(P<Path>, UseKind),
2080
2081     /// A `static` item
2082     ItemStatic(P<Ty>, Mutability, BodyId),
2083     /// A `const` item
2084     ItemConst(P<Ty>, BodyId),
2085     /// A function declaration
2086     ItemFn(P<FnDecl>, Unsafety, Constness, Abi, Generics, BodyId),
2087     /// A module
2088     ItemMod(Mod),
2089     /// An external module
2090     ItemForeignMod(ForeignMod),
2091     /// Module-level inline assembly (from global_asm!)
2092     ItemGlobalAsm(P<GlobalAsm>),
2093     /// A type alias, e.g. `type Foo = Bar<u8>`
2094     ItemTy(P<Ty>, Generics),
2095     /// A type alias, e.g. `type Foo = Bar<u8>`
2096     ItemExistential(ExistTy),
2097     /// An enum definition, e.g. `enum Foo<A, B> {C<A>, D<B>}`
2098     ItemEnum(EnumDef, Generics),
2099     /// A struct definition, e.g. `struct Foo<A> {x: A}`
2100     ItemStruct(VariantData, Generics),
2101     /// A union definition, e.g. `union Foo<A, B> {x: A, y: B}`
2102     ItemUnion(VariantData, Generics),
2103     /// Represents a Trait Declaration
2104     ItemTrait(IsAuto, Unsafety, Generics, TyParamBounds, HirVec<TraitItemRef>),
2105     /// Represents a Trait Alias Declaration
2106     ItemTraitAlias(Generics, TyParamBounds),
2107
2108     /// An implementation, eg `impl<A> Trait for Foo { .. }`
2109     ItemImpl(Unsafety,
2110              ImplPolarity,
2111              Defaultness,
2112              Generics,
2113              Option<TraitRef>, // (optional) trait this impl implements
2114              P<Ty>, // self
2115              HirVec<ImplItemRef>),
2116 }
2117
2118 impl Item_ {
2119     pub fn descriptive_variant(&self) -> &str {
2120         match *self {
2121             ItemExternCrate(..) => "extern crate",
2122             ItemUse(..) => "use",
2123             ItemStatic(..) => "static item",
2124             ItemConst(..) => "constant item",
2125             ItemFn(..) => "function",
2126             ItemMod(..) => "module",
2127             ItemForeignMod(..) => "foreign module",
2128             ItemGlobalAsm(..) => "global asm",
2129             ItemTy(..) => "type alias",
2130             ItemExistential(..) => "existential type",
2131             ItemEnum(..) => "enum",
2132             ItemStruct(..) => "struct",
2133             ItemUnion(..) => "union",
2134             ItemTrait(..) => "trait",
2135             ItemTraitAlias(..) => "trait alias",
2136             ItemImpl(..) => "item",
2137         }
2138     }
2139
2140     pub fn adt_kind(&self) -> Option<AdtKind> {
2141         match *self {
2142             ItemStruct(..) => Some(AdtKind::Struct),
2143             ItemUnion(..) => Some(AdtKind::Union),
2144             ItemEnum(..) => Some(AdtKind::Enum),
2145             _ => None,
2146         }
2147     }
2148
2149     pub fn generics(&self) -> Option<&Generics> {
2150         Some(match *self {
2151             ItemFn(_, _, _, _, ref generics, _) |
2152             ItemTy(_, ref generics) |
2153             ItemEnum(_, ref generics) |
2154             ItemStruct(_, ref generics) |
2155             ItemUnion(_, ref generics) |
2156             ItemTrait(_, _, ref generics, _, _) |
2157             ItemImpl(_, _, _, ref generics, _, _, _)=> generics,
2158             _ => return None
2159         })
2160     }
2161 }
2162
2163 /// A reference from an trait to one of its associated items. This
2164 /// contains the item's id, naturally, but also the item's name and
2165 /// some other high-level details (like whether it is an associated
2166 /// type or method, and whether it is public). This allows other
2167 /// passes to find the impl they want without loading the id (which
2168 /// means fewer edges in the incremental compilation graph).
2169 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2170 pub struct TraitItemRef {
2171     pub id: TraitItemId,
2172     pub name: Name,
2173     pub kind: AssociatedItemKind,
2174     pub span: Span,
2175     pub defaultness: Defaultness,
2176 }
2177
2178 /// A reference from an impl to one of its associated items. This
2179 /// contains the item's id, naturally, but also the item's name and
2180 /// some other high-level details (like whether it is an associated
2181 /// type or method, and whether it is public). This allows other
2182 /// passes to find the impl they want without loading the id (which
2183 /// means fewer edges in the incremental compilation graph).
2184 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2185 pub struct ImplItemRef {
2186     pub id: ImplItemId,
2187     pub name: Name,
2188     pub kind: AssociatedItemKind,
2189     pub span: Span,
2190     pub vis: Visibility,
2191     pub defaultness: Defaultness,
2192 }
2193
2194 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2195 pub enum AssociatedItemKind {
2196     Const,
2197     Method { has_self: bool },
2198     Type,
2199 }
2200
2201 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2202 pub struct ForeignItem {
2203     pub name: Name,
2204     pub attrs: HirVec<Attribute>,
2205     pub node: ForeignItem_,
2206     pub id: NodeId,
2207     pub span: Span,
2208     pub vis: Visibility,
2209 }
2210
2211 /// An item within an `extern` block
2212 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
2213 pub enum ForeignItem_ {
2214     /// A foreign function
2215     ForeignItemFn(P<FnDecl>, HirVec<Spanned<Name>>, Generics),
2216     /// A foreign static item (`static ext: u8`), with optional mutability
2217     /// (the boolean is true when mutable)
2218     ForeignItemStatic(P<Ty>, bool),
2219     /// A foreign type
2220     ForeignItemType,
2221 }
2222
2223 impl ForeignItem_ {
2224     pub fn descriptive_variant(&self) -> &str {
2225         match *self {
2226             ForeignItemFn(..) => "foreign function",
2227             ForeignItemStatic(..) => "foreign static item",
2228             ForeignItemType => "foreign type",
2229         }
2230     }
2231 }
2232
2233 /// A free variable referred to in a function.
2234 #[derive(Debug, Copy, Clone, RustcEncodable, RustcDecodable)]
2235 pub struct Freevar {
2236     /// The variable being accessed free.
2237     pub def: Def,
2238
2239     // First span where it is accessed (there can be multiple).
2240     pub span: Span
2241 }
2242
2243 impl Freevar {
2244     pub fn var_id(&self) -> NodeId {
2245         match self.def {
2246             Def::Local(id) | Def::Upvar(id, ..) => id,
2247             _ => bug!("Freevar::var_id: bad def ({:?})", self.def)
2248         }
2249     }
2250 }
2251
2252 pub type FreevarMap = NodeMap<Vec<Freevar>>;
2253
2254 pub type CaptureModeMap = NodeMap<CaptureClause>;
2255
2256 #[derive(Clone, Debug)]
2257 pub struct TraitCandidate {
2258     pub def_id: DefId,
2259     pub import_id: Option<NodeId>,
2260 }
2261
2262 // Trait method resolution
2263 pub type TraitMap = NodeMap<Vec<TraitCandidate>>;
2264
2265 // Map from the NodeId of a glob import to a list of items which are actually
2266 // imported.
2267 pub type GlobMap = NodeMap<FxHashSet<Name>>;
2268
2269
2270 pub fn provide(providers: &mut Providers) {
2271     providers.describe_def = map::describe_def;
2272 }
2273
2274 #[derive(Clone, RustcEncodable, RustcDecodable, Hash)]
2275 pub struct CodegenFnAttrs {
2276     pub flags: CodegenFnAttrFlags,
2277     pub inline: InlineAttr,
2278     pub export_name: Option<Symbol>,
2279     pub target_features: Vec<Symbol>,
2280     pub linkage: Option<Linkage>,
2281 }
2282
2283 bitflags! {
2284     #[derive(RustcEncodable, RustcDecodable)]
2285     pub struct CodegenFnAttrFlags: u8 {
2286         const COLD                      = 0b0000_0001;
2287         const ALLOCATOR                 = 0b0000_0010;
2288         const UNWIND                    = 0b0000_0100;
2289         const RUSTC_ALLOCATOR_NOUNWIND  = 0b0000_1000;
2290         const NAKED                     = 0b0001_0000;
2291         const NO_MANGLE                 = 0b0010_0000;
2292         const RUSTC_STD_INTERNAL_SYMBOL = 0b0100_0000;
2293         const NO_DEBUG                  = 0b1000_0000;
2294     }
2295 }
2296
2297 impl CodegenFnAttrs {
2298     pub fn new() -> CodegenFnAttrs {
2299         CodegenFnAttrs {
2300             flags: CodegenFnAttrFlags::empty(),
2301             inline: InlineAttr::None,
2302             export_name: None,
2303             target_features: vec![],
2304             linkage: None,
2305         }
2306     }
2307
2308     /// True if `#[inline]` or `#[inline(always)]` is present.
2309     pub fn requests_inline(&self) -> bool {
2310         match self.inline {
2311             InlineAttr::Hint | InlineAttr::Always => true,
2312             InlineAttr::None | InlineAttr::Never => false,
2313         }
2314     }
2315
2316     /// True if `#[no_mangle]` or `#[export_name(...)]` is present.
2317     pub fn contains_extern_indicator(&self) -> bool {
2318         self.flags.contains(CodegenFnAttrFlags::NO_MANGLE) || self.export_name.is_some()
2319     }
2320 }