src/librustc/hir/mod.rs

   1 //! HIR datatypes. See the [rustc guide] for more info.
   2 //!
   3 //! [rustc guide]: https://rust-lang.github.io/rustc-guide/hir.html
   4
   5 pub use self::BlockCheckMode::*;
   6 pub use self::CaptureClause::*;
   7 pub use self::FunctionRetTy::*;
   8 pub use self::Mutability::*;
   9 pub use self::PrimTy::*;
  10 pub use self::UnOp::*;
  11 pub use self::UnsafeSource::*;
  12
  13 use crate::hir::def::{Res, DefKind};
  14 use crate::hir::def_id::{DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX};
  15 use crate::hir::ptr::P;
  16 use crate::mir::mono::Linkage;
  17 use crate::ty::AdtKind;
  18 use crate::ty::query::Providers;
  19 use crate::util::nodemap::{NodeMap, FxHashSet};
  20
  21 use errors::FatalError;
  22 use syntax_pos::{Span, DUMMY_SP, MultiSpan};
  23 use syntax::source_map::Spanned;
  24 use syntax::ast::{self, CrateSugar, Ident, Name, NodeId, AsmDialect};
  25 use syntax::ast::{Attribute, Label, LitKind, StrStyle, FloatTy, IntTy, UintTy};
  26 use syntax::attr::{InlineAttr, OptimizeAttr};
  27 use syntax::symbol::{Symbol, kw};
  28 use syntax::tokenstream::TokenStream;
  29 use syntax::util::parser::ExprPrecedence;
  30 use rustc_target::spec::abi::Abi;
  31 use rustc_data_structures::sync::{par_for_each_in, Send, Sync};
  32 use rustc_data_structures::thin_vec::ThinVec;
  33 use rustc_macros::HashStable;
  34 use rustc_serialize::{self, Encoder, Encodable, Decoder, Decodable};
  35 use std::collections::{BTreeSet, BTreeMap};
  36 use std::fmt;
  37 use smallvec::SmallVec;
  38
  39 /// HIR doesn't commit to a concrete storage type and has its own alias for a vector.
  40 /// It can be `Vec`, `P<[T]>` or potentially `Box<[T]>`, or some other container with similar
  41 /// behavior. Unlike AST, HIR is mostly a static structure, so we can use an owned slice instead
  42 /// of `Vec` to avoid keeping extra capacity.
  43 pub type HirVec<T> = P<[T]>;
  44
  45 macro_rules! hir_vec {
  46     ($elem:expr; $n:expr) => (
  47         $crate::hir::HirVec::from(vec![$elem; $n])
  48     );
  49     ($($x:expr),*) => (
  50         $crate::hir::HirVec::from(vec![$($x),*])
  51     );
  52 }
  53
  54 pub mod check_attr;
  55 pub mod def;
  56 pub mod def_id;
  57 pub mod intravisit;
  58 pub mod itemlikevisit;
  59 pub mod lowering;
  60 pub mod map;
  61 pub mod pat_util;
  62 pub mod print;
  63 pub mod ptr;
  64 pub mod upvars;
  65
  66 /// Uniquely identifies a node in the HIR of the current crate. It is
  67 /// composed of the `owner`, which is the `DefIndex` of the directly enclosing
  68 /// `hir::Item`, `hir::TraitItem`, or `hir::ImplItem` (i.e., the closest "item-like"),
  69 /// and the `local_id` which is unique within the given owner.
  70 ///
  71 /// This two-level structure makes for more stable values: One can move an item
  72 /// around within the source code, or add or remove stuff before it, without
  73 /// the `local_id` part of the `HirId` changing, which is a very useful property in
  74 /// incremental compilation where we have to persist things through changes to
  75 /// the code base.
  76 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, PartialOrd, Ord)]
  77 pub struct HirId {
  78     pub owner: DefIndex,
  79     pub local_id: ItemLocalId,
  80 }
  81
  82 impl HirId {
  83     pub fn owner_def_id(self) -> DefId {
  84         DefId::local(self.owner)
  85     }
  86
  87     pub fn owner_local_def_id(self) -> LocalDefId {
  88         LocalDefId::from_def_id(DefId::local(self.owner))
  89     }
  90 }
  91
  92 impl rustc_serialize::UseSpecializedEncodable for HirId {
  93     fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
  94         let HirId {
  95             owner,
  96             local_id,
  97         } = *self;
  98
  99         owner.encode(s)?;
 100         local_id.encode(s)?;
 101         Ok(())
 102     }
 103 }
 104
 105 impl rustc_serialize::UseSpecializedDecodable for HirId {
 106     fn default_decode<D: Decoder>(d: &mut D) -> Result<HirId, D::Error> {
 107         let owner = DefIndex::decode(d)?;
 108         let local_id = ItemLocalId::decode(d)?;
 109
 110         Ok(HirId {
 111             owner,
 112             local_id
 113         })
 114     }
 115 }
 116
 117 impl fmt::Display for HirId {
 118     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 119         write!(f, "{:?}", self)
 120     }
 121 }
 122
 123 // Hack to ensure that we don't try to access the private parts of `ItemLocalId` in this module.
 124 mod item_local_id_inner {
 125     use rustc_index::vec::Idx;
 126     use rustc_macros::HashStable;
 127     rustc_index::newtype_index! {
 128         /// An `ItemLocalId` uniquely identifies something within a given "item-like";
 129         /// that is, within a `hir::Item`, `hir::TraitItem`, or `hir::ImplItem`. There is no
 130         /// guarantee that the numerical value of a given `ItemLocalId` corresponds to
 131         /// the node's position within the owning item in any way, but there is a
 132         /// guarantee that the `LocalItemId`s within an owner occupy a dense range of
 133         /// integers starting at zero, so a mapping that maps all or most nodes within
 134         /// an "item-like" to something else can be implemented by a `Vec` instead of a
 135         /// tree or hash map.
 136         pub struct ItemLocalId {
 137             derive [HashStable]
 138         }
 139     }
 140 }
 141
 142 pub use self::item_local_id_inner::ItemLocalId;
 143
 144 /// The `HirId` corresponding to `CRATE_NODE_ID` and `CRATE_DEF_INDEX`.
 145 pub const CRATE_HIR_ID: HirId = HirId {
 146     owner: CRATE_DEF_INDEX,
 147     local_id: ItemLocalId::from_u32_const(0)
 148 };
 149
 150 pub const DUMMY_HIR_ID: HirId = HirId {
 151     owner: CRATE_DEF_INDEX,
 152     local_id: DUMMY_ITEM_LOCAL_ID,
 153 };
 154
 155 pub const DUMMY_ITEM_LOCAL_ID: ItemLocalId = ItemLocalId::MAX;
 156
 157 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, HashStable)]
 158 pub struct Lifetime {
 159     pub hir_id: HirId,
 160     pub span: Span,
 161
 162     /// Either "`'a`", referring to a named lifetime definition,
 163     /// or "``" (i.e., `kw::Invalid`), for elision placeholders.
 164     ///
 165     /// HIR lowering inserts these placeholders in type paths that
 166     /// refer to type definitions needing lifetime parameters,
 167     /// `&T` and `&mut T`, and trait objects without `... + 'a`.
 168     pub name: LifetimeName,
 169 }
 170
 171 #[derive(Debug, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy, HashStable)]
 172 pub enum ParamName {
 173     /// Some user-given name like `T` or `'x`.
 174     Plain(Ident),
 175
 176     /// Synthetic name generated when user elided a lifetime in an impl header.
 177     ///
 178     /// E.g., the lifetimes in cases like these:
 179     ///
 180     ///     impl Foo for &u32
 181     ///     impl Foo<'_> for u32
 182     ///
 183     /// in that case, we rewrite to
 184     ///
 185     ///     impl<'f> Foo for &'f u32
 186     ///     impl<'f> Foo<'f> for u32
 187     ///
 188     /// where `'f` is something like `Fresh(0)`. The indices are
 189     /// unique per impl, but not necessarily continuous.
 190     Fresh(usize),
 191
 192     /// Indicates an illegal name was given and an error has been
 193     /// reported (so we should squelch other derived errors). Occurs
 194     /// when, e.g., `'_` is used in the wrong place.
 195     Error,
 196 }
 197
 198 impl ParamName {
 199     pub fn ident(&self) -> Ident {
 200         match *self {
 201             ParamName::Plain(ident) => ident,
 202             ParamName::Fresh(_) |
 203             ParamName::Error => Ident::with_dummy_span(kw::UnderscoreLifetime),
 204         }
 205     }
 206
 207     pub fn modern(&self) -> ParamName {
 208         match *self {
 209             ParamName::Plain(ident) => ParamName::Plain(ident.modern()),
 210             param_name => param_name,
 211         }
 212     }
 213 }
 214
 215 #[derive(Debug, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy, HashStable)]
 216 pub enum LifetimeName {
 217     /// User-given names or fresh (synthetic) names.
 218     Param(ParamName),
 219
 220     /// User wrote nothing (e.g., the lifetime in `&u32`).
 221     Implicit,
 222
 223     /// Implicit lifetime in a context like `dyn Foo`. This is
 224     /// distinguished from implicit lifetimes elsewhere because the
 225     /// lifetime that they default to must appear elsewhere within the
 226     /// enclosing type.  This means that, in an `impl Trait` context, we
 227     /// don't have to create a parameter for them. That is, `impl
 228     /// Trait<Item = &u32>` expands to an opaque type like `type
 229     /// Foo<'a> = impl Trait<Item = &'a u32>`, but `impl Trait<item =
 230     /// dyn Bar>` expands to `type Foo = impl Trait<Item = dyn Bar +
 231     /// 'static>`. The latter uses `ImplicitObjectLifetimeDefault` so
 232     /// that surrounding code knows not to create a lifetime
 233     /// parameter.
 234     ImplicitObjectLifetimeDefault,
 235
 236     /// Indicates an error during lowering (usually `'_` in wrong place)
 237     /// that was already reported.
 238     Error,
 239
 240     /// User wrote specifies `'_`.
 241     Underscore,
 242
 243     /// User wrote `'static`.
 244     Static,
 245 }
 246
 247 impl LifetimeName {
 248     pub fn ident(&self) -> Ident {
 249         match *self {
 250             LifetimeName::ImplicitObjectLifetimeDefault
 251                 | LifetimeName::Implicit
 252                 | LifetimeName::Error => Ident::invalid(),
 253             LifetimeName::Underscore => Ident::with_dummy_span(kw::UnderscoreLifetime),
 254             LifetimeName::Static => Ident::with_dummy_span(kw::StaticLifetime),
 255             LifetimeName::Param(param_name) => param_name.ident(),
 256         }
 257     }
 258
 259     pub fn is_elided(&self) -> bool {
 260         match self {
 261             LifetimeName::ImplicitObjectLifetimeDefault
 262             | LifetimeName::Implicit
 263             | LifetimeName::Underscore => true,
 264
 265             // It might seem surprising that `Fresh(_)` counts as
 266             // *not* elided -- but this is because, as far as the code
 267             // in the compiler is concerned -- `Fresh(_)` variants act
 268             // equivalently to "some fresh name". They correspond to
 269             // early-bound regions on an impl, in other words.
 270             LifetimeName::Error | LifetimeName::Param(_) | LifetimeName::Static => false,
 271         }
 272     }
 273
 274     fn is_static(&self) -> bool {
 275         self == &LifetimeName::Static
 276     }
 277
 278     pub fn modern(&self) -> LifetimeName {
 279         match *self {
 280             LifetimeName::Param(param_name) => LifetimeName::Param(param_name.modern()),
 281             lifetime_name => lifetime_name,
 282         }
 283     }
 284 }
 285
 286 impl fmt::Display for Lifetime {
 287     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 288         self.name.ident().fmt(f)
 289     }
 290 }
 291
 292 impl fmt::Debug for Lifetime {
 293     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 294         write!(f,
 295                "lifetime({}: {})",
 296                self.hir_id,
 297                print::to_string(print::NO_ANN, |s| s.print_lifetime(self)))
 298     }
 299 }
 300
 301 impl Lifetime {
 302     pub fn is_elided(&self) -> bool {
 303         self.name.is_elided()
 304     }
 305
 306     pub fn is_static(&self) -> bool {
 307         self.name.is_static()
 308     }
 309 }
 310
 311 /// A `Path` is essentially Rust's notion of a name; for instance,
 312 /// `std::cmp::PartialEq`. It's represented as a sequence of identifiers,
 313 /// along with a bunch of supporting information.
 314 #[derive(RustcEncodable, RustcDecodable, HashStable)]
 315 pub struct Path {
 316     pub span: Span,
 317     /// The resolution for the path.
 318     pub res: Res,
 319     /// The segments in the path: the things separated by `::`.
 320     pub segments: HirVec<PathSegment>,
 321 }
 322
 323 impl Path {
 324     pub fn is_global(&self) -> bool {
 325         !self.segments.is_empty() && self.segments[0].ident.name == kw::PathRoot
 326     }
 327 }
 328
 329 impl fmt::Debug for Path {
 330     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 331         write!(f, "path({})", self)
 332     }
 333 }
 334
 335 impl fmt::Display for Path {
 336     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 337         write!(f, "{}", print::to_string(print::NO_ANN, |s| s.print_path(self, false)))
 338     }
 339 }
 340
 341 /// A segment of a path: an identifier, an optional lifetime, and a set of
 342 /// types.
 343 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 344 pub struct PathSegment {
 345     /// The identifier portion of this path segment.
 346     #[stable_hasher(project(name))]
 347     pub ident: Ident,
 348     // `id` and `res` are optional. We currently only use these in save-analysis,
 349     // any path segments without these will not have save-analysis info and
 350     // therefore will not have 'jump to def' in IDEs, but otherwise will not be
 351     // affected. (In general, we don't bother to get the defs for synthesized
 352     // segments, only for segments which have come from the AST).
 353     pub hir_id: Option<HirId>,
 354     pub res: Option<Res>,
 355
 356     /// Type/lifetime parameters attached to this path. They come in
 357     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
 358     /// this is more than just simple syntactic sugar; the use of
 359     /// parens affects the region binding rules, so we preserve the
 360     /// distinction.
 361     pub args: Option<P<GenericArgs>>,
 362
 363     /// Whether to infer remaining type parameters, if any.
 364     /// This only applies to expression and pattern paths, and
 365     /// out of those only the segments with no type parameters
 366     /// to begin with, e.g., `Vec::new` is `<Vec<..>>::new::<..>`.
 367     pub infer_args: bool,
 368 }
 369
 370 impl PathSegment {
 371     /// Converts an identifier to the corresponding segment.
 372     pub fn from_ident(ident: Ident) -> PathSegment {
 373         PathSegment {
 374             ident,
 375             hir_id: None,
 376             res: None,
 377             infer_args: true,
 378             args: None,
 379         }
 380     }
 381
 382     pub fn new(
 383         ident: Ident,
 384         hir_id: Option<HirId>,
 385         res: Option<Res>,
 386         args: GenericArgs,
 387         infer_args: bool,
 388     ) -> Self {
 389         PathSegment {
 390             ident,
 391             hir_id,
 392             res,
 393             infer_args,
 394             args: if args.is_empty() {
 395                 None
 396             } else {
 397                 Some(P(args))
 398             }
 399         }
 400     }
 401
 402     pub fn generic_args(&self) -> &GenericArgs {
 403         if let Some(ref args) = self.args {
 404             args
 405         } else {
 406             const DUMMY: &GenericArgs = &GenericArgs::none();
 407             DUMMY
 408         }
 409     }
 410 }
 411
 412 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 413 pub struct ConstArg {
 414     pub value: AnonConst,
 415     pub span: Span,
 416 }
 417
 418 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 419 pub enum GenericArg {
 420     Lifetime(Lifetime),
 421     Type(Ty),
 422     Const(ConstArg),
 423 }
 424
 425 impl GenericArg {
 426     pub fn span(&self) -> Span {
 427         match self {
 428             GenericArg::Lifetime(l) => l.span,
 429             GenericArg::Type(t) => t.span,
 430             GenericArg::Const(c) => c.span,
 431         }
 432     }
 433
 434     pub fn id(&self) -> HirId {
 435         match self {
 436             GenericArg::Lifetime(l) => l.hir_id,
 437             GenericArg::Type(t) => t.hir_id,
 438             GenericArg::Const(c) => c.value.hir_id,
 439         }
 440     }
 441
 442     pub fn is_const(&self) -> bool {
 443         match self {
 444             GenericArg::Const(_) => true,
 445             _ => false,
 446         }
 447     }
 448 }
 449
 450 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 451 pub struct GenericArgs {
 452     /// The generic arguments for this path segment.
 453     pub args: HirVec<GenericArg>,
 454     /// Bindings (equality constraints) on associated types, if present.
 455     /// E.g., `Foo<A = Bar>`.
 456     pub bindings: HirVec<TypeBinding>,
 457     /// Were arguments written in parenthesized form `Fn(T) -> U`?
 458     /// This is required mostly for pretty-printing and diagnostics,
 459     /// but also for changing lifetime elision rules to be "function-like".
 460     pub parenthesized: bool,
 461 }
 462
 463 impl GenericArgs {
 464     pub const fn none() -> Self {
 465         Self {
 466             args: HirVec::new(),
 467             bindings: HirVec::new(),
 468             parenthesized: false,
 469         }
 470     }
 471
 472     pub fn is_empty(&self) -> bool {
 473         self.args.is_empty() && self.bindings.is_empty() && !self.parenthesized
 474     }
 475
 476     pub fn inputs(&self) -> &[Ty] {
 477         if self.parenthesized {
 478             for arg in &self.args {
 479                 match arg {
 480                     GenericArg::Lifetime(_) => {}
 481                     GenericArg::Type(ref ty) => {
 482                         if let TyKind::Tup(ref tys) = ty.kind {
 483                             return tys;
 484                         }
 485                         break;
 486                     }
 487                     GenericArg::Const(_) => {}
 488                 }
 489             }
 490         }
 491         bug!("GenericArgs::inputs: not a `Fn(T) -> U`");
 492     }
 493
 494     pub fn own_counts(&self) -> GenericParamCount {
 495         // We could cache this as a property of `GenericParamCount`, but
 496         // the aim is to refactor this away entirely eventually and the
 497         // presence of this method will be a constant reminder.
 498         let mut own_counts: GenericParamCount = Default::default();
 499
 500         for arg in &self.args {
 501             match arg {
 502                 GenericArg::Lifetime(_) => own_counts.lifetimes += 1,
 503                 GenericArg::Type(_) => own_counts.types += 1,
 504                 GenericArg::Const(_) => own_counts.consts += 1,
 505             };
 506         }
 507
 508         own_counts
 509     }
 510 }
 511
 512 /// A modifier on a bound, currently this is only used for `?Sized`, where the
 513 /// modifier is `Maybe`. Negative bounds should also be handled here.
 514 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
 515 pub enum TraitBoundModifier {
 516     None,
 517     Maybe,
 518 }
 519
 520 /// The AST represents all type param bounds as types.
 521 /// `typeck::collect::compute_bounds` matches these against
 522 /// the "special" built-in traits (see `middle::lang_items`) and
 523 /// detects `Copy`, `Send` and `Sync`.
 524 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 525 pub enum GenericBound {
 526     Trait(PolyTraitRef, TraitBoundModifier),
 527     Outlives(Lifetime),
 528 }
 529
 530 impl GenericBound {
 531     pub fn span(&self) -> Span {
 532         match self {
 533             &GenericBound::Trait(ref t, ..) => t.span,
 534             &GenericBound::Outlives(ref l) => l.span,
 535         }
 536     }
 537 }
 538
 539 pub type GenericBounds = HirVec<GenericBound>;
 540
 541 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug, HashStable)]
 542 pub enum LifetimeParamKind {
 543     // Indicates that the lifetime definition was explicitly declared (e.g., in
 544     // `fn foo<'a>(x: &'a u8) -> &'a u8 { x }`).
 545     Explicit,
 546
 547     // Indicates that the lifetime definition was synthetically added
 548     // as a result of an in-band lifetime usage (e.g., in
 549     // `fn foo(x: &'a u8) -> &'a u8 { x }`).
 550     InBand,
 551
 552     // Indication that the lifetime was elided (e.g., in both cases in
 553     // `fn foo(x: &u8) -> &'_ u8 { x }`).
 554     Elided,
 555
 556     // Indication that the lifetime name was somehow in error.
 557     Error,
 558 }
 559
 560 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 561 pub enum GenericParamKind {
 562     /// A lifetime definition (e.g., `'a: 'b + 'c + 'd`).
 563     Lifetime {
 564         kind: LifetimeParamKind,
 565     },
 566     Type {
 567         default: Option<P<Ty>>,
 568         synthetic: Option<SyntheticTyParamKind>,
 569     },
 570     Const {
 571         ty: P<Ty>,
 572     }
 573 }
 574
 575 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 576 pub struct GenericParam {
 577     pub hir_id: HirId,
 578     pub name: ParamName,
 579     pub attrs: HirVec<Attribute>,
 580     pub bounds: GenericBounds,
 581     pub span: Span,
 582     pub pure_wrt_drop: bool,
 583     pub kind: GenericParamKind,
 584 }
 585
 586 #[derive(Default)]
 587 pub struct GenericParamCount {
 588     pub lifetimes: usize,
 589     pub types: usize,
 590     pub consts: usize,
 591 }
 592
 593 /// Represents lifetimes and type parameters attached to a declaration
 594 /// of a function, enum, trait, etc.
 595 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 596 pub struct Generics {
 597     pub params: HirVec<GenericParam>,
 598     pub where_clause: WhereClause,
 599     pub span: Span,
 600 }
 601
 602 impl Generics {
 603     pub const fn empty() -> Generics {
 604         Generics {
 605             params: HirVec::new(),
 606             where_clause: WhereClause {
 607                 predicates: HirVec::new(),
 608                 span: DUMMY_SP,
 609             },
 610             span: DUMMY_SP,
 611         }
 612     }
 613
 614     pub fn own_counts(&self) -> GenericParamCount {
 615         // We could cache this as a property of `GenericParamCount`, but
 616         // the aim is to refactor this away entirely eventually and the
 617         // presence of this method will be a constant reminder.
 618         let mut own_counts: GenericParamCount = Default::default();
 619
 620         for param in &self.params {
 621             match param.kind {
 622                 GenericParamKind::Lifetime { .. } => own_counts.lifetimes += 1,
 623                 GenericParamKind::Type { .. } => own_counts.types += 1,
 624                 GenericParamKind::Const { .. } => own_counts.consts += 1,
 625             };
 626         }
 627
 628         own_counts
 629     }
 630
 631     pub fn get_named(&self, name: Symbol) -> Option<&GenericParam> {
 632         for param in &self.params {
 633             if name == param.name.ident().name {
 634                 return Some(param);
 635             }
 636         }
 637         None
 638     }
 639
 640     pub fn spans(&self) -> MultiSpan {
 641         if self.params.is_empty() {
 642             self.span.into()
 643         } else {
 644             self.params.iter().map(|p| p.span).collect::<Vec<Span>>().into()
 645         }
 646     }
 647 }
 648
 649 /// Synthetic type parameters are converted to another form during lowering; this allows
 650 /// us to track the original form they had, and is useful for error messages.
 651 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
 652 pub enum SyntheticTyParamKind {
 653     ImplTrait
 654 }
 655
 656 /// A where-clause in a definition.
 657 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 658 pub struct WhereClause {
 659     pub predicates: HirVec<WherePredicate>,
 660     // Only valid if predicates isn't empty.
 661     span: Span,
 662 }
 663
 664 impl WhereClause {
 665     pub fn span(&self) -> Option<Span> {
 666         if self.predicates.is_empty() {
 667             None
 668         } else {
 669             Some(self.span)
 670         }
 671     }
 672
 673     /// The `WhereClause` under normal circumstances points at either the predicates or the empty
 674     /// space where the `where` clause should be. Only of use for diagnostic suggestions.
 675     pub fn span_for_predicates_or_empty_place(&self) -> Span {
 676         self.span
 677     }
 678 }
 679
 680 /// A single predicate in a where-clause.
 681 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 682 pub enum WherePredicate {
 683     /// A type binding (e.g., `for<'c> Foo: Send + Clone + 'c`).
 684     BoundPredicate(WhereBoundPredicate),
 685     /// A lifetime predicate (e.g., `'a: 'b + 'c`).
 686     RegionPredicate(WhereRegionPredicate),
 687     /// An equality predicate (unsupported).
 688     EqPredicate(WhereEqPredicate),
 689 }
 690
 691 impl WherePredicate {
 692     pub fn span(&self) -> Span {
 693         match self {
 694             &WherePredicate::BoundPredicate(ref p) => p.span,
 695             &WherePredicate::RegionPredicate(ref p) => p.span,
 696             &WherePredicate::EqPredicate(ref p) => p.span,
 697         }
 698     }
 699 }
 700
 701 /// A type bound (e.g., `for<'c> Foo: Send + Clone + 'c`).
 702 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 703 pub struct WhereBoundPredicate {
 704     pub span: Span,
 705     /// Any generics from a `for` binding.
 706     pub bound_generic_params: HirVec<GenericParam>,
 707     /// The type being bounded.
 708     pub bounded_ty: P<Ty>,
 709     /// Trait and lifetime bounds (e.g., `Clone + Send + 'static`).
 710     pub bounds: GenericBounds,
 711 }
 712
 713 /// A lifetime predicate (e.g., `'a: 'b + 'c`).
 714 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 715 pub struct WhereRegionPredicate {
 716     pub span: Span,
 717     pub lifetime: Lifetime,
 718     pub bounds: GenericBounds,
 719 }
 720
 721 /// An equality predicate (e.g., `T = int`); currently unsupported.
 722 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 723 pub struct WhereEqPredicate {
 724     pub hir_id: HirId,
 725     pub span: Span,
 726     pub lhs_ty: P<Ty>,
 727     pub rhs_ty: P<Ty>,
 728 }
 729
 730 #[derive(RustcEncodable, RustcDecodable, Debug)]
 731 pub struct ModuleItems {
 732     // Use BTreeSets here so items are in the same order as in the
 733     // list of all items in Crate
 734     pub items: BTreeSet<HirId>,
 735     pub trait_items: BTreeSet<TraitItemId>,
 736     pub impl_items: BTreeSet<ImplItemId>,
 737 }
 738
 739 /// The top-level data structure that stores the entire contents of
 740 /// the crate currently being compiled.
 741 ///
 742 /// For more details, see the [rustc guide].
 743 ///
 744 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/hir.html
 745 #[derive(RustcEncodable, RustcDecodable, Debug)]
 746 pub struct Crate {
 747     pub module: Mod,
 748     pub attrs: HirVec<Attribute>,
 749     pub span: Span,
 750     pub exported_macros: HirVec<MacroDef>,
 751     // Attributes from non-exported macros, kept only for collecting the library feature list.
 752     pub non_exported_macro_attrs: HirVec<Attribute>,
 753
 754     // N.B., we use a `BTreeMap` here so that `visit_all_items` iterates
 755     // over the ids in increasing order. In principle it should not
 756     // matter what order we visit things in, but in *practice* it
 757     // does, because it can affect the order in which errors are
 758     // detected, which in turn can make compile-fail tests yield
 759     // slightly different results.
 760     pub items: BTreeMap<HirId, Item>,
 761
 762     pub trait_items: BTreeMap<TraitItemId, TraitItem>,
 763     pub impl_items: BTreeMap<ImplItemId, ImplItem>,
 764     pub bodies: BTreeMap<BodyId, Body>,
 765     pub trait_impls: BTreeMap<DefId, Vec<HirId>>,
 766
 767     /// A list of the body ids written out in the order in which they
 768     /// appear in the crate. If you're going to process all the bodies
 769     /// in the crate, you should iterate over this list rather than the keys
 770     /// of bodies.
 771     pub body_ids: Vec<BodyId>,
 772
 773     /// A list of modules written out in the order in which they
 774     /// appear in the crate. This includes the main crate module.
 775     pub modules: BTreeMap<HirId, ModuleItems>,
 776 }
 777
 778 impl Crate {
 779     pub fn item(&self, id: HirId) -> &Item {
 780         &self.items[&id]
 781     }
 782
 783     pub fn trait_item(&self, id: TraitItemId) -> &TraitItem {
 784         &self.trait_items[&id]
 785     }
 786
 787     pub fn impl_item(&self, id: ImplItemId) -> &ImplItem {
 788         &self.impl_items[&id]
 789     }
 790
 791     /// Visits all items in the crate in some deterministic (but
 792     /// unspecified) order. If you just need to process every item,
 793     /// but don't care about nesting, this method is the best choice.
 794     ///
 795     /// If you do care about nesting -- usually because your algorithm
 796     /// follows lexical scoping rules -- then you want a different
 797     /// approach. You should override `visit_nested_item` in your
 798     /// visitor and then call `intravisit::walk_crate` instead.
 799     pub fn visit_all_item_likes<'hir, V>(&'hir self, visitor: &mut V)
 800         where V: itemlikevisit::ItemLikeVisitor<'hir>
 801     {
 802         for (_, item) in &self.items {
 803             visitor.visit_item(item);
 804         }
 805
 806         for (_, trait_item) in &self.trait_items {
 807             visitor.visit_trait_item(trait_item);
 808         }
 809
 810         for (_, impl_item) in &self.impl_items {
 811             visitor.visit_impl_item(impl_item);
 812         }
 813     }
 814
 815     /// A parallel version of `visit_all_item_likes`.
 816     pub fn par_visit_all_item_likes<'hir, V>(&'hir self, visitor: &V)
 817         where V: itemlikevisit::ParItemLikeVisitor<'hir> + Sync + Send
 818     {
 819         parallel!({
 820             par_for_each_in(&self.items, |(_, item)| {
 821                 visitor.visit_item(item);
 822             });
 823         }, {
 824             par_for_each_in(&self.trait_items, |(_, trait_item)| {
 825                 visitor.visit_trait_item(trait_item);
 826             });
 827         }, {
 828             par_for_each_in(&self.impl_items, |(_, impl_item)| {
 829                 visitor.visit_impl_item(impl_item);
 830             });
 831         });
 832     }
 833
 834     pub fn body(&self, id: BodyId) -> &Body {
 835         &self.bodies[&id]
 836     }
 837 }
 838
 839 /// A macro definition, in this crate or imported from another.
 840 ///
 841 /// Not parsed directly, but created on macro import or `macro_rules!` expansion.
 842 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 843 pub struct MacroDef {
 844     pub name: Name,
 845     pub vis: Visibility,
 846     pub attrs: HirVec<Attribute>,
 847     pub hir_id: HirId,
 848     pub span: Span,
 849     pub body: TokenStream,
 850     pub legacy: bool,
 851 }
 852
 853 /// A block of statements `{ .. }`, which may have a label (in this case the
 854 /// `targeted_by_break` field will be `true`) and may be `unsafe` by means of
 855 /// the `rules` being anything but `DefaultBlock`.
 856 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 857 pub struct Block {
 858     /// Statements in a block.
 859     pub stmts: HirVec<Stmt>,
 860     /// An expression at the end of the block
 861     /// without a semicolon, if any.
 862     pub expr: Option<P<Expr>>,
 863     #[stable_hasher(ignore)]
 864     pub hir_id: HirId,
 865     /// Distinguishes between `unsafe { ... }` and `{ ... }`.
 866     pub rules: BlockCheckMode,
 867     pub span: Span,
 868     /// If true, then there may exist `break 'a` values that aim to
 869     /// break out of this block early.
 870     /// Used by `'label: {}` blocks and by `try {}` blocks.
 871     pub targeted_by_break: bool,
 872 }
 873
 874 #[derive(RustcEncodable, RustcDecodable, HashStable)]
 875 pub struct Pat {
 876     #[stable_hasher(ignore)]
 877     pub hir_id: HirId,
 878     pub kind: PatKind,
 879     pub span: Span,
 880 }
 881
 882 impl fmt::Debug for Pat {
 883     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 884         write!(f, "pat({}: {})", self.hir_id,
 885                print::to_string(print::NO_ANN, |s| s.print_pat(self)))
 886     }
 887 }
 888
 889 impl Pat {
 890     // FIXME(#19596) this is a workaround, but there should be a better way
 891     fn walk_short_(&self, it: &mut impl FnMut(&Pat) -> bool) -> bool {
 892         if !it(self) {
 893             return false;
 894         }
 895
 896         use PatKind::*;
 897         match &self.kind {
 898             Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => true,
 899             Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_short_(it),
 900             Struct(_, fields, _) => fields.iter().all(|field| field.pat.walk_short_(it)),
 901             TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().all(|p| p.walk_short_(it)),
 902             Slice(before, slice, after) => {
 903                 before.iter()
 904                       .chain(slice.iter())
 905                       .chain(after.iter())
 906                       .all(|p| p.walk_short_(it))
 907             }
 908         }
 909     }
 910
 911     /// Walk the pattern in left-to-right order,
 912     /// short circuiting (with `.all(..)`) if `false` is returned.
 913     ///
 914     /// Note that when visiting e.g. `Tuple(ps)`,
 915     /// if visiting `ps[0]` returns `false`,
 916     /// then `ps[1]` will not be visited.
 917     pub fn walk_short(&self, mut it: impl FnMut(&Pat) -> bool) -> bool {
 918         self.walk_short_(&mut it)
 919     }
 920
 921     // FIXME(#19596) this is a workaround, but there should be a better way
 922     fn walk_(&self, it: &mut impl FnMut(&Pat) -> bool) {
 923         if !it(self) {
 924             return;
 925         }
 926
 927         use PatKind::*;
 928         match &self.kind {
 929             Wild | Lit(_) | Range(..) | Binding(.., None) | Path(_) => {},
 930             Box(s) | Ref(s, _) | Binding(.., Some(s)) => s.walk_(it),
 931             Struct(_, fields, _) => fields.iter().for_each(|field| field.pat.walk_(it)),
 932             TupleStruct(_, s, _) | Tuple(s, _) | Or(s) => s.iter().for_each(|p| p.walk_(it)),
 933             Slice(before, slice, after) => {
 934                 before.iter()
 935                       .chain(slice.iter())
 936                       .chain(after.iter())
 937                       .for_each(|p| p.walk_(it))
 938             }
 939         }
 940     }
 941
 942     /// Walk the pattern in left-to-right order.
 943     ///
 944     /// If `it(pat)` returns `false`, the children are not visited.
 945     pub fn walk(&self, mut it: impl FnMut(&Pat) -> bool) {
 946         self.walk_(&mut it)
 947     }
 948 }
 949
 950 /// A single field in a struct pattern.
 951 ///
 952 /// Patterns like the fields of Foo `{ x, ref y, ref mut z }`
 953 /// are treated the same as` x: x, y: ref y, z: ref mut z`,
 954 /// except `is_shorthand` is true.
 955 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 956 pub struct FieldPat {
 957     #[stable_hasher(ignore)]
 958     pub hir_id: HirId,
 959     /// The identifier for the field.
 960     #[stable_hasher(project(name))]
 961     pub ident: Ident,
 962     /// The pattern the field is destructured to.
 963     pub pat: P<Pat>,
 964     pub is_shorthand: bool,
 965     pub span: Span,
 966 }
 967
 968 /// Explicit binding annotations given in the HIR for a binding. Note
 969 /// that this is not the final binding *mode* that we infer after type
 970 /// inference.
 971 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
 972 pub enum BindingAnnotation {
 973     /// No binding annotation given: this means that the final binding mode
 974     /// will depend on whether we have skipped through a `&` reference
 975     /// when matching. For example, the `x` in `Some(x)` will have binding
 976     /// mode `None`; if you do `let Some(x) = &Some(22)`, it will
 977     /// ultimately be inferred to be by-reference.
 978     ///
 979     /// Note that implicit reference skipping is not implemented yet (#42640).
 980     Unannotated,
 981
 982     /// Annotated with `mut x` -- could be either ref or not, similar to `None`.
 983     Mutable,
 984
 985     /// Annotated as `ref`, like `ref x`
 986     Ref,
 987
 988     /// Annotated as `ref mut x`.
 989     RefMut,
 990 }
 991
 992 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
 993 pub enum RangeEnd {
 994     Included,
 995     Excluded,
 996 }
 997
 998 impl fmt::Display for RangeEnd {
 999     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1000         f.write_str(match self {
1001             RangeEnd::Included => "..=",
1002             RangeEnd::Excluded => "..",
1003         })
1004     }
1005 }
1006
1007 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1008 pub enum PatKind {
1009     /// Represents a wildcard pattern (i.e., `_`).
1010     Wild,
1011
1012     /// A fresh binding `ref mut binding @ OPT_SUBPATTERN`.
1013     /// The `HirId` is the canonical ID for the variable being bound,
1014     /// (e.g., in `Ok(x) | Err(x)`, both `x` use the same canonical ID),
1015     /// which is the pattern ID of the first `x`.
1016     Binding(BindingAnnotation, HirId, Ident, Option<P<Pat>>),
1017
1018     /// A struct or struct variant pattern (e.g., `Variant {x, y, ..}`).
1019     /// The `bool` is `true` in the presence of a `..`.
1020     Struct(QPath, HirVec<FieldPat>, bool),
1021
1022     /// A tuple struct/variant pattern `Variant(x, y, .., z)`.
1023     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
1024     /// `0 <= position <= subpats.len()`
1025     TupleStruct(QPath, HirVec<P<Pat>>, Option<usize>),
1026
1027     /// An or-pattern `A | B | C`.
1028     /// Invariant: `pats.len() >= 2`.
1029     Or(HirVec<P<Pat>>),
1030
1031     /// A path pattern for an unit struct/variant or a (maybe-associated) constant.
1032     Path(QPath),
1033
1034     /// A tuple pattern (e.g., `(a, b)`).
1035     /// If the `..` pattern fragment is present, then `Option<usize>` denotes its position.
1036     /// `0 <= position <= subpats.len()`
1037     Tuple(HirVec<P<Pat>>, Option<usize>),
1038
1039     /// A `box` pattern.
1040     Box(P<Pat>),
1041
1042     /// A reference pattern (e.g., `&mut (a, b)`).
1043     Ref(P<Pat>, Mutability),
1044
1045     /// A literal.
1046     Lit(P<Expr>),
1047
1048     /// A range pattern (e.g., `1..=2` or `1..2`).
1049     Range(P<Expr>, P<Expr>, RangeEnd),
1050
1051     /// `[a, b, ..i, y, z]` is represented as:
1052     ///     `PatKind::Slice(box [a, b], Some(i), box [y, z])`.
1053     Slice(HirVec<P<Pat>>, Option<P<Pat>>, HirVec<P<Pat>>),
1054 }
1055
1056 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, HashStable,
1057          RustcEncodable, RustcDecodable, Hash, Debug)]
1058 pub enum Mutability {
1059     MutMutable,
1060     MutImmutable,
1061 }
1062
1063 impl Mutability {
1064     /// Returns `MutMutable` only if both `self` and `other` are mutable.
1065     pub fn and(self, other: Self) -> Self {
1066         match self {
1067             MutMutable => other,
1068             MutImmutable => MutImmutable,
1069         }
1070     }
1071
1072     pub fn invert(self) -> Self {
1073         match self {
1074             MutMutable => MutImmutable,
1075             MutImmutable => MutMutable,
1076         }
1077     }
1078 }
1079
1080 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1081 pub enum BinOpKind {
1082     /// The `+` operator (addition).
1083     Add,
1084     /// The `-` operator (subtraction).
1085     Sub,
1086     /// The `*` operator (multiplication).
1087     Mul,
1088     /// The `/` operator (division).
1089     Div,
1090     /// The `%` operator (modulus).
1091     Rem,
1092     /// The `&&` operator (logical and).
1093     And,
1094     /// The `||` operator (logical or).
1095     Or,
1096     /// The `^` operator (bitwise xor).
1097     BitXor,
1098     /// The `&` operator (bitwise and).
1099     BitAnd,
1100     /// The `|` operator (bitwise or).
1101     BitOr,
1102     /// The `<<` operator (shift left).
1103     Shl,
1104     /// The `>>` operator (shift right).
1105     Shr,
1106     /// The `==` operator (equality).
1107     Eq,
1108     /// The `<` operator (less than).
1109     Lt,
1110     /// The `<=` operator (less than or equal to).
1111     Le,
1112     /// The `!=` operator (not equal to).
1113     Ne,
1114     /// The `>=` operator (greater than or equal to).
1115     Ge,
1116     /// The `>` operator (greater than).
1117     Gt,
1118 }
1119
1120 impl BinOpKind {
1121     pub fn as_str(self) -> &'static str {
1122         match self {
1123             BinOpKind::Add => "+",
1124             BinOpKind::Sub => "-",
1125             BinOpKind::Mul => "*",
1126             BinOpKind::Div => "/",
1127             BinOpKind::Rem => "%",
1128             BinOpKind::And => "&&",
1129             BinOpKind::Or => "||",
1130             BinOpKind::BitXor => "^",
1131             BinOpKind::BitAnd => "&",
1132             BinOpKind::BitOr => "|",
1133             BinOpKind::Shl => "<<",
1134             BinOpKind::Shr => ">>",
1135             BinOpKind::Eq => "==",
1136             BinOpKind::Lt => "<",
1137             BinOpKind::Le => "<=",
1138             BinOpKind::Ne => "!=",
1139             BinOpKind::Ge => ">=",
1140             BinOpKind::Gt => ">",
1141         }
1142     }
1143
1144     pub fn is_lazy(self) -> bool {
1145         match self {
1146             BinOpKind::And | BinOpKind::Or => true,
1147             _ => false,
1148         }
1149     }
1150
1151     pub fn is_shift(self) -> bool {
1152         match self {
1153             BinOpKind::Shl | BinOpKind::Shr => true,
1154             _ => false,
1155         }
1156     }
1157
1158     pub fn is_comparison(self) -> bool {
1159         match self {
1160             BinOpKind::Eq |
1161             BinOpKind::Lt |
1162             BinOpKind::Le |
1163             BinOpKind::Ne |
1164             BinOpKind::Gt |
1165             BinOpKind::Ge => true,
1166             BinOpKind::And |
1167             BinOpKind::Or |
1168             BinOpKind::Add |
1169             BinOpKind::Sub |
1170             BinOpKind::Mul |
1171             BinOpKind::Div |
1172             BinOpKind::Rem |
1173             BinOpKind::BitXor |
1174             BinOpKind::BitAnd |
1175             BinOpKind::BitOr |
1176             BinOpKind::Shl |
1177             BinOpKind::Shr => false,
1178         }
1179     }
1180
1181     /// Returns `true` if the binary operator takes its arguments by value.
1182     pub fn is_by_value(self) -> bool {
1183         !self.is_comparison()
1184     }
1185 }
1186
1187 impl Into<ast::BinOpKind> for BinOpKind {
1188     fn into(self) -> ast::BinOpKind {
1189         match self {
1190             BinOpKind::Add => ast::BinOpKind::Add,
1191             BinOpKind::Sub => ast::BinOpKind::Sub,
1192             BinOpKind::Mul => ast::BinOpKind::Mul,
1193             BinOpKind::Div => ast::BinOpKind::Div,
1194             BinOpKind::Rem => ast::BinOpKind::Rem,
1195             BinOpKind::And => ast::BinOpKind::And,
1196             BinOpKind::Or => ast::BinOpKind::Or,
1197             BinOpKind::BitXor => ast::BinOpKind::BitXor,
1198             BinOpKind::BitAnd => ast::BinOpKind::BitAnd,
1199             BinOpKind::BitOr => ast::BinOpKind::BitOr,
1200             BinOpKind::Shl => ast::BinOpKind::Shl,
1201             BinOpKind::Shr => ast::BinOpKind::Shr,
1202             BinOpKind::Eq => ast::BinOpKind::Eq,
1203             BinOpKind::Lt => ast::BinOpKind::Lt,
1204             BinOpKind::Le => ast::BinOpKind::Le,
1205             BinOpKind::Ne => ast::BinOpKind::Ne,
1206             BinOpKind::Ge => ast::BinOpKind::Ge,
1207             BinOpKind::Gt => ast::BinOpKind::Gt,
1208         }
1209     }
1210 }
1211
1212 pub type BinOp = Spanned<BinOpKind>;
1213
1214 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1215 pub enum UnOp {
1216     /// The `*` operator (deferencing).
1217     UnDeref,
1218     /// The `!` operator (logical negation).
1219     UnNot,
1220     /// The `-` operator (negation).
1221     UnNeg,
1222 }
1223
1224 impl UnOp {
1225     pub fn as_str(self) -> &'static str {
1226         match self {
1227             UnDeref => "*",
1228             UnNot => "!",
1229             UnNeg => "-",
1230         }
1231     }
1232
1233     /// Returns `true` if the unary operator takes its argument by value.
1234     pub fn is_by_value(self) -> bool {
1235         match self {
1236             UnNeg | UnNot => true,
1237             _ => false,
1238         }
1239     }
1240 }
1241
1242 /// A statement.
1243 #[derive(RustcEncodable, RustcDecodable)]
1244 pub struct Stmt {
1245     pub hir_id: HirId,
1246     pub kind: StmtKind,
1247     pub span: Span,
1248 }
1249
1250 impl fmt::Debug for Stmt {
1251     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1252         write!(f, "stmt({}: {})", self.hir_id,
1253                print::to_string(print::NO_ANN, |s| s.print_stmt(self)))
1254     }
1255 }
1256
1257 /// The contents of a statement.
1258 #[derive(RustcEncodable, RustcDecodable, HashStable)]
1259 pub enum StmtKind {
1260     /// A local (`let`) binding.
1261     Local(P<Local>),
1262
1263     /// An item binding.
1264     Item(ItemId),
1265
1266     /// An expression without a trailing semi-colon (must have unit type).
1267     Expr(P<Expr>),
1268
1269     /// An expression with a trailing semi-colon (may have any type).
1270     Semi(P<Expr>),
1271 }
1272
1273 impl StmtKind {
1274     pub fn attrs(&self) -> &[Attribute] {
1275         match *self {
1276             StmtKind::Local(ref l) => &l.attrs,
1277             StmtKind::Item(_) => &[],
1278             StmtKind::Expr(ref e) |
1279             StmtKind::Semi(ref e) => &e.attrs,
1280         }
1281     }
1282 }
1283
1284 /// Represents a `let` statement (i.e., `let <pat>:<ty> = <expr>;`).
1285 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1286 pub struct Local {
1287     pub pat: P<Pat>,
1288     /// Type annotation, if any (otherwise the type will be inferred).
1289     pub ty: Option<P<Ty>>,
1290     /// Initializer expression to set the value, if any.
1291     pub init: Option<P<Expr>>,
1292     pub hir_id: HirId,
1293     pub span: Span,
1294     pub attrs: ThinVec<Attribute>,
1295     /// Can be `ForLoopDesugar` if the `let` statement is part of a `for` loop
1296     /// desugaring. Otherwise will be `Normal`.
1297     pub source: LocalSource,
1298 }
1299
1300 /// Represents a single arm of a `match` expression, e.g.
1301 /// `<pat> (if <guard>) => <body>`.
1302 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1303 pub struct Arm {
1304     #[stable_hasher(ignore)]
1305     pub hir_id: HirId,
1306     pub span: Span,
1307     pub attrs: HirVec<Attribute>,
1308     /// If this pattern and the optional guard matches, then `body` is evaluated.
1309     pub pat: P<Pat>,
1310     /// Optional guard clause.
1311     pub guard: Option<Guard>,
1312     /// The expression the arm evaluates to if this arm matches.
1313     pub body: P<Expr>,
1314 }
1315
1316 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1317 pub enum Guard {
1318     If(P<Expr>),
1319 }
1320
1321 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1322 pub struct Field {
1323     #[stable_hasher(ignore)]
1324     pub hir_id: HirId,
1325     pub ident: Ident,
1326     pub expr: P<Expr>,
1327     pub span: Span,
1328     pub is_shorthand: bool,
1329 }
1330
1331 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1332 pub enum BlockCheckMode {
1333     DefaultBlock,
1334     UnsafeBlock(UnsafeSource),
1335     PushUnsafeBlock(UnsafeSource),
1336     PopUnsafeBlock(UnsafeSource),
1337 }
1338
1339 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1340 pub enum UnsafeSource {
1341     CompilerGenerated,
1342     UserProvided,
1343 }
1344
1345 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
1346 pub struct BodyId {
1347     pub hir_id: HirId,
1348 }
1349
1350 /// The body of a function, closure, or constant value. In the case of
1351 /// a function, the body contains not only the function body itself
1352 /// (which is an expression), but also the argument patterns, since
1353 /// those are something that the caller doesn't really care about.
1354 ///
1355 /// # Examples
1356 ///
1357 /// ```
1358 /// fn foo((x, y): (u32, u32)) -> u32 {
1359 ///     x + y
1360 /// }
1361 /// ```
1362 ///
1363 /// Here, the `Body` associated with `foo()` would contain:
1364 ///
1365 /// - an `params` array containing the `(x, y)` pattern
1366 /// - a `value` containing the `x + y` expression (maybe wrapped in a block)
1367 /// - `generator_kind` would be `None`
1368 ///
1369 /// All bodies have an **owner**, which can be accessed via the HIR
1370 /// map using `body_owner_def_id()`.
1371 #[derive(RustcEncodable, RustcDecodable, Debug)]
1372 pub struct Body {
1373     pub params: HirVec<Param>,
1374     pub value: Expr,
1375     pub generator_kind: Option<GeneratorKind>,
1376 }
1377
1378 impl Body {
1379     pub fn id(&self) -> BodyId {
1380         BodyId {
1381             hir_id: self.value.hir_id,
1382         }
1383     }
1384
1385     pub fn generator_kind(&self) -> Option<GeneratorKind> {
1386         self.generator_kind
1387     }
1388 }
1389
1390 /// The type of source expression that caused this generator to be created.
1391 #[derive(Clone, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable, Debug, Copy)]
1392 pub enum GeneratorKind {
1393     /// An explicit `async` block or the body of an async function.
1394     Async(AsyncGeneratorKind),
1395
1396     /// A generator literal created via a `yield` inside a closure.
1397     Gen,
1398 }
1399
1400 impl fmt::Display for GeneratorKind {
1401     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1402         match self {
1403             GeneratorKind::Async(k) => fmt::Display::fmt(k, f),
1404             GeneratorKind::Gen => f.write_str("generator"),
1405         }
1406     }
1407 }
1408
1409 /// In the case of a generator created as part of an async construct,
1410 /// which kind of async construct caused it to be created?
1411 ///
1412 /// This helps error messages but is also used to drive coercions in
1413 /// type-checking (see #60424).
1414 #[derive(Clone, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable, Debug, Copy)]
1415 pub enum AsyncGeneratorKind {
1416     /// An explicit `async` block written by the user.
1417     Block,
1418
1419     /// An explicit `async` block written by the user.
1420     Closure,
1421
1422     /// The `async` block generated as the body of an async function.
1423     Fn,
1424 }
1425
1426 impl fmt::Display for AsyncGeneratorKind {
1427     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1428         f.write_str(match self {
1429             AsyncGeneratorKind::Block => "`async` block",
1430             AsyncGeneratorKind::Closure => "`async` closure body",
1431             AsyncGeneratorKind::Fn => "`async fn` body",
1432         })
1433     }
1434 }
1435
1436 #[derive(Copy, Clone, Debug)]
1437 pub enum BodyOwnerKind {
1438     /// Functions and methods.
1439     Fn,
1440
1441     /// Closures
1442     Closure,
1443
1444     /// Constants and associated constants.
1445     Const,
1446
1447     /// Initializer of a `static` item.
1448     Static(Mutability),
1449 }
1450
1451 impl BodyOwnerKind {
1452     pub fn is_fn_or_closure(self) -> bool {
1453         match self {
1454             BodyOwnerKind::Fn | BodyOwnerKind::Closure => true,
1455             BodyOwnerKind::Const | BodyOwnerKind::Static(_) => false,
1456         }
1457     }
1458 }
1459
1460 /// A literal.
1461 pub type Lit = Spanned<LitKind>;
1462
1463 /// A constant (expression) that's not an item or associated item,
1464 /// but needs its own `DefId` for type-checking, const-eval, etc.
1465 /// These are usually found nested inside types (e.g., array lengths)
1466 /// or expressions (e.g., repeat counts), and also used to define
1467 /// explicit discriminant values for enum variants.
1468 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1469 pub struct AnonConst {
1470     pub hir_id: HirId,
1471     pub body: BodyId,
1472 }
1473
1474 /// An expression.
1475 #[derive(RustcEncodable, RustcDecodable)]
1476 pub struct Expr {
1477     pub hir_id: HirId,
1478     pub kind: ExprKind,
1479     pub attrs: ThinVec<Attribute>,
1480     pub span: Span,
1481 }
1482
1483 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
1484 #[cfg(target_arch = "x86_64")]
1485 static_assert_size!(Expr, 72);
1486
1487 impl Expr {
1488     pub fn precedence(&self) -> ExprPrecedence {
1489         match self.kind {
1490             ExprKind::Box(_) => ExprPrecedence::Box,
1491             ExprKind::Array(_) => ExprPrecedence::Array,
1492             ExprKind::Call(..) => ExprPrecedence::Call,
1493             ExprKind::MethodCall(..) => ExprPrecedence::MethodCall,
1494             ExprKind::Tup(_) => ExprPrecedence::Tup,
1495             ExprKind::Binary(op, ..) => ExprPrecedence::Binary(op.node.into()),
1496             ExprKind::Unary(..) => ExprPrecedence::Unary,
1497             ExprKind::Lit(_) => ExprPrecedence::Lit,
1498             ExprKind::Type(..) | ExprKind::Cast(..) => ExprPrecedence::Cast,
1499             ExprKind::DropTemps(ref expr, ..) => expr.precedence(),
1500             ExprKind::Loop(..) => ExprPrecedence::Loop,
1501             ExprKind::Match(..) => ExprPrecedence::Match,
1502             ExprKind::Closure(..) => ExprPrecedence::Closure,
1503             ExprKind::Block(..) => ExprPrecedence::Block,
1504             ExprKind::Assign(..) => ExprPrecedence::Assign,
1505             ExprKind::AssignOp(..) => ExprPrecedence::AssignOp,
1506             ExprKind::Field(..) => ExprPrecedence::Field,
1507             ExprKind::Index(..) => ExprPrecedence::Index,
1508             ExprKind::Path(..) => ExprPrecedence::Path,
1509             ExprKind::AddrOf(..) => ExprPrecedence::AddrOf,
1510             ExprKind::Break(..) => ExprPrecedence::Break,
1511             ExprKind::Continue(..) => ExprPrecedence::Continue,
1512             ExprKind::Ret(..) => ExprPrecedence::Ret,
1513             ExprKind::InlineAsm(..) => ExprPrecedence::InlineAsm,
1514             ExprKind::Struct(..) => ExprPrecedence::Struct,
1515             ExprKind::Repeat(..) => ExprPrecedence::Repeat,
1516             ExprKind::Yield(..) => ExprPrecedence::Yield,
1517             ExprKind::Err => ExprPrecedence::Err,
1518         }
1519     }
1520
1521     pub fn is_place_expr(&self) -> bool {
1522          match self.kind {
1523             ExprKind::Path(QPath::Resolved(_, ref path)) => {
1524                 match path.res {
1525                     Res::Local(..)
1526                     | Res::Def(DefKind::Static, _)
1527                     | Res::Err => true,
1528                     _ => false,
1529                 }
1530             }
1531
1532             ExprKind::Type(ref e, _) => {
1533                 e.is_place_expr()
1534             }
1535
1536             ExprKind::Unary(UnDeref, _) |
1537             ExprKind::Field(..) |
1538             ExprKind::Index(..) => {
1539                 true
1540             }
1541
1542             // Partially qualified paths in expressions can only legally
1543             // refer to associated items which are always rvalues.
1544             ExprKind::Path(QPath::TypeRelative(..)) |
1545
1546             ExprKind::Call(..) |
1547             ExprKind::MethodCall(..) |
1548             ExprKind::Struct(..) |
1549             ExprKind::Tup(..) |
1550             ExprKind::Match(..) |
1551             ExprKind::Closure(..) |
1552             ExprKind::Block(..) |
1553             ExprKind::Repeat(..) |
1554             ExprKind::Array(..) |
1555             ExprKind::Break(..) |
1556             ExprKind::Continue(..) |
1557             ExprKind::Ret(..) |
1558             ExprKind::Loop(..) |
1559             ExprKind::Assign(..) |
1560             ExprKind::InlineAsm(..) |
1561             ExprKind::AssignOp(..) |
1562             ExprKind::Lit(_) |
1563             ExprKind::Unary(..) |
1564             ExprKind::Box(..) |
1565             ExprKind::AddrOf(..) |
1566             ExprKind::Binary(..) |
1567             ExprKind::Yield(..) |
1568             ExprKind::Cast(..) |
1569             ExprKind::DropTemps(..) |
1570             ExprKind::Err => {
1571                 false
1572             }
1573         }
1574     }
1575
1576     /// If `Self.kind` is `ExprKind::DropTemps(expr)`, drill down until we get a non-`DropTemps`
1577     /// `Expr`. This is used in suggestions to ignore this `ExprKind` as it is semantically
1578     /// silent, only signaling the ownership system. By doing this, suggestions that check the
1579     /// `ExprKind` of any given `Expr` for presentation don't have to care about `DropTemps`
1580     /// beyond remembering to call this function before doing analysis on it.
1581     pub fn peel_drop_temps(&self) -> &Self {
1582         let mut expr = self;
1583         while let ExprKind::DropTemps(inner) = &expr.kind {
1584             expr = inner;
1585         }
1586         expr
1587     }
1588 }
1589
1590 impl fmt::Debug for Expr {
1591     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1592         write!(f, "expr({}: {})", self.hir_id,
1593                print::to_string(print::NO_ANN, |s| s.print_expr(self)))
1594     }
1595 }
1596
1597 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1598 pub enum ExprKind {
1599     /// A `box x` expression.
1600     Box(P<Expr>),
1601     /// An array (e.g., `[a, b, c, d]`).
1602     Array(HirVec<Expr>),
1603     /// A function call.
1604     ///
1605     /// The first field resolves to the function itself (usually an `ExprKind::Path`),
1606     /// and the second field is the list of arguments.
1607     /// This also represents calling the constructor of
1608     /// tuple-like ADTs such as tuple structs and enum variants.
1609     Call(P<Expr>, HirVec<Expr>),
1610     /// A method call (e.g., `x.foo::<'static, Bar, Baz>(a, b, c, d)`).
1611     ///
1612     /// The `PathSegment`/`Span` represent the method name and its generic arguments
1613     /// (within the angle brackets).
1614     /// The first element of the vector of `Expr`s is the expression that evaluates
1615     /// to the object on which the method is being called on (the receiver),
1616     /// and the remaining elements are the rest of the arguments.
1617     /// Thus, `x.foo::<Bar, Baz>(a, b, c, d)` is represented as
1618     /// `ExprKind::MethodCall(PathSegment { foo, [Bar, Baz] }, [x, a, b, c, d])`.
1619     MethodCall(P<PathSegment>, Span, HirVec<Expr>),
1620     /// A tuple (e.g., `(a, b, c, d)`).
1621     Tup(HirVec<Expr>),
1622     /// A binary operation (e.g., `a + b`, `a * b`).
1623     Binary(BinOp, P<Expr>, P<Expr>),
1624     /// A unary operation (e.g., `!x`, `*x`).
1625     Unary(UnOp, P<Expr>),
1626     /// A literal (e.g., `1`, `"foo"`).
1627     Lit(Lit),
1628     /// A cast (e.g., `foo as f64`).
1629     Cast(P<Expr>, P<Ty>),
1630     /// A type reference (e.g., `Foo`).
1631     Type(P<Expr>, P<Ty>),
1632     /// Wraps the expression in a terminating scope.
1633     /// This makes it semantically equivalent to `{ let _t = expr; _t }`.
1634     ///
1635     /// This construct only exists to tweak the drop order in HIR lowering.
1636     /// An example of that is the desugaring of `for` loops.
1637     DropTemps(P<Expr>),
1638     /// A conditionless loop (can be exited with `break`, `continue`, or `return`).
1639     ///
1640     /// I.e., `'label: loop { <block> }`.
1641     Loop(P<Block>, Option<Label>, LoopSource),
1642     /// A `match` block, with a source that indicates whether or not it is
1643     /// the result of a desugaring, and if so, which kind.
1644     Match(P<Expr>, HirVec<Arm>, MatchSource),
1645     /// A closure (e.g., `move |a, b, c| {a + b + c}`).
1646     ///
1647     /// The `Span` is the argument block `|...|`.
1648     ///
1649     /// This may also be a generator literal or an `async block` as indicated by the
1650     /// `Option<GeneratorMovability>`.
1651     Closure(CaptureClause, P<FnDecl>, BodyId, Span, Option<GeneratorMovability>),
1652     /// A block (e.g., `'label: { ... }`).
1653     Block(P<Block>, Option<Label>),
1654
1655     /// An assignment (e.g., `a = foo()`).
1656     Assign(P<Expr>, P<Expr>),
1657     /// An assignment with an operator.
1658     ///
1659     /// E.g., `a += 1`.
1660     AssignOp(BinOp, P<Expr>, P<Expr>),
1661     /// Access of a named (e.g., `obj.foo`) or unnamed (e.g., `obj.0`) struct or tuple field.
1662     Field(P<Expr>, Ident),
1663     /// An indexing operation (`foo[2]`).
1664     Index(P<Expr>, P<Expr>),
1665
1666     /// Path to a definition, possibly containing lifetime or type parameters.
1667     Path(QPath),
1668
1669     /// A referencing operation (i.e., `&a` or `&mut a`).
1670     AddrOf(Mutability, P<Expr>),
1671     /// A `break`, with an optional label to break.
1672     Break(Destination, Option<P<Expr>>),
1673     /// A `continue`, with an optional label.
1674     Continue(Destination),
1675     /// A `return`, with an optional value to be returned.
1676     Ret(Option<P<Expr>>),
1677
1678     /// Inline assembly (from `asm!`), with its outputs and inputs.
1679     InlineAsm(P<InlineAsm>, HirVec<Expr>, HirVec<Expr>),
1680
1681     /// A struct or struct-like variant literal expression.
1682     ///
1683     /// E.g., `Foo {x: 1, y: 2}`, or `Foo {x: 1, .. base}`,
1684     /// where `base` is the `Option<Expr>`.
1685     Struct(P<QPath>, HirVec<Field>, Option<P<Expr>>),
1686
1687     /// An array literal constructed from one repeated element.
1688     ///
1689     /// E.g., `[1; 5]`. The first expression is the element
1690     /// to be repeated; the second is the number of times to repeat it.
1691     Repeat(P<Expr>, AnonConst),
1692
1693     /// A suspension point for generators (i.e., `yield <expr>`).
1694     Yield(P<Expr>, YieldSource),
1695
1696     /// A placeholder for an expression that wasn't syntactically well formed in some way.
1697     Err,
1698 }
1699
1700 /// Represents an optionally `Self`-qualified value/type path or associated extension.
1701 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1702 pub enum QPath {
1703     /// Path to a definition, optionally "fully-qualified" with a `Self`
1704     /// type, if the path points to an associated item in a trait.
1705     ///
1706     /// E.g., an unqualified path like `Clone::clone` has `None` for `Self`,
1707     /// while `<Vec<T> as Clone>::clone` has `Some(Vec<T>)` for `Self`,
1708     /// even though they both have the same two-segment `Clone::clone` `Path`.
1709     Resolved(Option<P<Ty>>, P<Path>),
1710
1711     /// Type-related paths (e.g., `<T>::default` or `<T>::Output`).
1712     /// Will be resolved by type-checking to an associated item.
1713     ///
1714     /// UFCS source paths can desugar into this, with `Vec::new` turning into
1715     /// `<Vec>::new`, and `T::X::Y::method` into `<<<T>::X>::Y>::method`,
1716     /// the `X` and `Y` nodes each being a `TyKind::Path(QPath::TypeRelative(..))`.
1717     TypeRelative(P<Ty>, P<PathSegment>)
1718 }
1719
1720 /// Hints at the original code for a let statement.
1721 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
1722 pub enum LocalSource {
1723     /// A `match _ { .. }`.
1724     Normal,
1725     /// A desugared `for _ in _ { .. }` loop.
1726     ForLoopDesugar,
1727     /// When lowering async functions, we create locals within the `async move` so that
1728     /// all parameters are dropped after the future is polled.
1729     ///
1730     /// ```ignore (pseudo-Rust)
1731     /// async fn foo(<pattern> @ x: Type) {
1732     ///     async move {
1733     ///         let <pattern> = x;
1734     ///     }
1735     /// }
1736     /// ```
1737     AsyncFn,
1738     /// A desugared `<expr>.await`.
1739     AwaitDesugar,
1740 }
1741
1742 /// Hints at the original code for a `match _ { .. }`.
1743 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
1744 pub enum MatchSource {
1745     /// A `match _ { .. }`.
1746     Normal,
1747     /// An `if _ { .. }` (optionally with `else { .. }`).
1748     IfDesugar {
1749         contains_else_clause: bool,
1750     },
1751     /// An `if let _ = _ { .. }` (optionally with `else { .. }`).
1752     IfLetDesugar {
1753         contains_else_clause: bool,
1754     },
1755     /// A `while _ { .. }` (which was desugared to a `loop { match _ { .. } }`).
1756     WhileDesugar,
1757     /// A `while let _ = _ { .. }` (which was desugared to a
1758     /// `loop { match _ { .. } }`).
1759     WhileLetDesugar,
1760     /// A desugared `for _ in _ { .. }` loop.
1761     ForLoopDesugar,
1762     /// A desugared `?` operator.
1763     TryDesugar,
1764     /// A desugared `<expr>.await`.
1765     AwaitDesugar,
1766 }
1767
1768 /// The loop type that yielded an `ExprKind::Loop`.
1769 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
1770 pub enum LoopSource {
1771     /// A `loop { .. }` loop.
1772     Loop,
1773     /// A `while _ { .. }` loop.
1774     While,
1775     /// A `while let _ = _ { .. }` loop.
1776     WhileLet,
1777     /// A `for _ in _ { .. }` loop.
1778     ForLoop,
1779 }
1780
1781 impl LoopSource {
1782     pub fn name(self) -> &'static str {
1783         match self {
1784             LoopSource::Loop => "loop",
1785             LoopSource::While => "while",
1786             LoopSource::WhileLet => "while let",
1787             LoopSource::ForLoop => "for",
1788         }
1789     }
1790 }
1791
1792 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
1793 pub enum LoopIdError {
1794     OutsideLoopScope,
1795     UnlabeledCfInWhileCondition,
1796     UnresolvedLabel,
1797 }
1798
1799 impl fmt::Display for LoopIdError {
1800     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1801         f.write_str(match self {
1802             LoopIdError::OutsideLoopScope => "not inside loop scope",
1803             LoopIdError::UnlabeledCfInWhileCondition =>
1804                 "unlabeled control flow (break or continue) in while condition",
1805             LoopIdError::UnresolvedLabel => "label not found",
1806         })
1807     }
1808 }
1809
1810 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
1811 pub struct Destination {
1812     // This is `Some(_)` iff there is an explicit user-specified `label
1813     pub label: Option<Label>,
1814
1815     // These errors are caught and then reported during the diagnostics pass in
1816     // librustc_passes/loops.rs
1817     pub target_id: Result<HirId, LoopIdError>,
1818 }
1819
1820 /// Whether a generator contains self-references, causing it to be `!Unpin`.
1821 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, HashStable,
1822          RustcEncodable, RustcDecodable, Hash, Debug)]
1823 pub enum GeneratorMovability {
1824     /// May contain self-references, `!Unpin`.
1825     Static,
1826
1827     /// Must not contain self-references, `Unpin`.
1828     Movable,
1829 }
1830
1831 /// The yield kind that caused an `ExprKind::Yield`.
1832 #[derive(Copy, Clone, PartialEq, Eq, Debug, RustcEncodable, RustcDecodable, HashStable)]
1833 pub enum YieldSource {
1834     /// An `<expr>.await`.
1835     Await,
1836     /// A plain `yield`.
1837     Yield,
1838 }
1839
1840 impl fmt::Display for YieldSource {
1841     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1842         f.write_str(match self {
1843             YieldSource::Await => "`await`",
1844             YieldSource::Yield => "`yield`",
1845         })
1846     }
1847 }
1848
1849 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
1850 pub enum CaptureClause {
1851     CaptureByValue,
1852     CaptureByRef,
1853 }
1854
1855 // N.B., if you change this, you'll probably want to change the corresponding
1856 // type structure in middle/ty.rs as well.
1857 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1858 pub struct MutTy {
1859     pub ty: P<Ty>,
1860     pub mutbl: Mutability,
1861 }
1862
1863 /// Represents a method's signature in a trait declaration or implementation.
1864 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1865 pub struct MethodSig {
1866     pub header: FnHeader,
1867     pub decl: P<FnDecl>,
1868 }
1869
1870 // The bodies for items are stored "out of line", in a separate
1871 // hashmap in the `Crate`. Here we just record the node-id of the item
1872 // so it can fetched later.
1873 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Debug)]
1874 pub struct TraitItemId {
1875     pub hir_id: HirId,
1876 }
1877
1878 /// Represents an item declaration within a trait declaration,
1879 /// possibly including a default implementation. A trait item is
1880 /// either required (meaning it doesn't have an implementation, just a
1881 /// signature) or provided (meaning it has a default implementation).
1882 #[derive(RustcEncodable, RustcDecodable, Debug)]
1883 pub struct TraitItem {
1884     pub ident: Ident,
1885     pub hir_id: HirId,
1886     pub attrs: HirVec<Attribute>,
1887     pub generics: Generics,
1888     pub kind: TraitItemKind,
1889     pub span: Span,
1890 }
1891
1892 /// Represents a trait method's body (or just argument names).
1893 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1894 pub enum TraitMethod {
1895     /// No default body in the trait, just a signature.
1896     Required(HirVec<Ident>),
1897
1898     /// Both signature and body are provided in the trait.
1899     Provided(BodyId),
1900 }
1901
1902 /// Represents a trait method or associated constant or type
1903 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1904 pub enum TraitItemKind {
1905     /// An associated constant with an optional value (otherwise `impl`s must contain a value).
1906     Const(P<Ty>, Option<BodyId>),
1907     /// A method with an optional body.
1908     Method(MethodSig, TraitMethod),
1909     /// An associated type with (possibly empty) bounds and optional concrete
1910     /// type.
1911     Type(GenericBounds, Option<P<Ty>>),
1912 }
1913
1914 // The bodies for items are stored "out of line", in a separate
1915 // hashmap in the `Crate`. Here we just record the node-id of the item
1916 // so it can fetched later.
1917 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Debug)]
1918 pub struct ImplItemId {
1919     pub hir_id: HirId,
1920 }
1921
1922 /// Represents anything within an `impl` block.
1923 #[derive(RustcEncodable, RustcDecodable, Debug)]
1924 pub struct ImplItem {
1925     pub ident: Ident,
1926     pub hir_id: HirId,
1927     pub vis: Visibility,
1928     pub defaultness: Defaultness,
1929     pub attrs: HirVec<Attribute>,
1930     pub generics: Generics,
1931     pub kind: ImplItemKind,
1932     pub span: Span,
1933 }
1934
1935 /// Represents various kinds of content within an `impl`.
1936 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1937 pub enum ImplItemKind {
1938     /// An associated constant of the given type, set to the constant result
1939     /// of the expression.
1940     Const(P<Ty>, BodyId),
1941     /// A method implementation with the given signature and body.
1942     Method(MethodSig, BodyId),
1943     /// An associated type.
1944     TyAlias(P<Ty>),
1945     /// An associated `type = impl Trait`.
1946     OpaqueTy(GenericBounds),
1947 }
1948
1949 /// Bind a type to an associated type (i.e., `A = Foo`).
1950 ///
1951 /// Bindings like `A: Debug` are represented as a special type `A =
1952 /// $::Debug` that is understood by the astconv code.
1953 ///
1954 /// FIXME(alexreg) -- why have a separate type for the binding case,
1955 /// wouldn't it be better to make the `ty` field an enum like:
1956 ///
1957 /// ```
1958 /// enum TypeBindingKind {
1959 ///    Equals(...),
1960 ///    Binding(...),
1961 /// }
1962 /// ```
1963 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1964 pub struct TypeBinding {
1965     pub hir_id: HirId,
1966     #[stable_hasher(project(name))]
1967     pub ident: Ident,
1968     pub kind: TypeBindingKind,
1969     pub span: Span,
1970 }
1971
1972 // Represents the two kinds of type bindings.
1973 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
1974 pub enum TypeBindingKind {
1975     /// E.g., `Foo<Bar: Send>`.
1976     Constraint {
1977         bounds: HirVec<GenericBound>,
1978     },
1979     /// E.g., `Foo<Bar = ()>`.
1980     Equality {
1981         ty: P<Ty>,
1982     },
1983 }
1984
1985 impl TypeBinding {
1986     pub fn ty(&self) -> &Ty {
1987         match self.kind {
1988             TypeBindingKind::Equality { ref ty } => ty,
1989             _ => bug!("expected equality type binding for parenthesized generic args"),
1990         }
1991     }
1992 }
1993
1994 #[derive(RustcEncodable, RustcDecodable)]
1995 pub struct Ty {
1996     pub hir_id: HirId,
1997     pub kind: TyKind,
1998     pub span: Span,
1999 }
2000
2001 impl fmt::Debug for Ty {
2002     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2003         write!(f, "type({})",
2004                print::to_string(print::NO_ANN, |s| s.print_type(self)))
2005     }
2006 }
2007
2008 /// Not represented directly in the AST; referred to by name through a `ty_path`.
2009 #[derive(Copy, Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, HashStable)]
2010 pub enum PrimTy {
2011     Int(IntTy),
2012     Uint(UintTy),
2013     Float(FloatTy),
2014     Str,
2015     Bool,
2016     Char,
2017 }
2018
2019 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2020 pub struct BareFnTy {
2021     pub unsafety: Unsafety,
2022     pub abi: Abi,
2023     pub generic_params: HirVec<GenericParam>,
2024     pub decl: P<FnDecl>,
2025     pub param_names: HirVec<Ident>,
2026 }
2027
2028 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2029 pub struct OpaqueTy {
2030     pub generics: Generics,
2031     pub bounds: GenericBounds,
2032     pub impl_trait_fn: Option<DefId>,
2033     pub origin: OpaqueTyOrigin,
2034 }
2035
2036 /// From whence the opaque type came.
2037 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
2038 pub enum OpaqueTyOrigin {
2039     /// `type Foo = impl Trait;`
2040     TypeAlias,
2041     /// `-> impl Trait`
2042     FnReturn,
2043     /// `async fn`
2044     AsyncFn,
2045 }
2046
2047 /// The various kinds of types recognized by the compiler.
2048 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2049 pub enum TyKind {
2050     /// A variable length slice (i.e., `[T]`).
2051     Slice(P<Ty>),
2052     /// A fixed length array (i.e., `[T; n]`).
2053     Array(P<Ty>, AnonConst),
2054     /// A raw pointer (i.e., `*const T` or `*mut T`).
2055     Ptr(MutTy),
2056     /// A reference (i.e., `&'a T` or `&'a mut T`).
2057     Rptr(Lifetime, MutTy),
2058     /// A bare function (e.g., `fn(usize) -> bool`).
2059     BareFn(P<BareFnTy>),
2060     /// The never type (`!`).
2061     Never,
2062     /// A tuple (`(A, B, C, D, ...)`).
2063     Tup(HirVec<Ty>),
2064     /// A path to a type definition (`module::module::...::Type`), or an
2065     /// associated type (e.g., `<Vec<T> as Trait>::Type` or `<T>::Target`).
2066     ///
2067     /// Type parameters may be stored in each `PathSegment`.
2068     Path(QPath),
2069     /// A type definition itself. This is currently only used for the `type Foo = impl Trait`
2070     /// item that `impl Trait` in return position desugars to.
2071     ///
2072     /// The generic argument list contains the lifetimes (and in the future possibly parameters)
2073     /// that are actually bound on the `impl Trait`.
2074     Def(ItemId, HirVec<GenericArg>),
2075     /// A trait object type `Bound1 + Bound2 + Bound3`
2076     /// where `Bound` is a trait or a lifetime.
2077     TraitObject(HirVec<PolyTraitRef>, Lifetime),
2078     /// Unused for now.
2079     Typeof(AnonConst),
2080     /// `TyKind::Infer` means the type should be inferred instead of it having been
2081     /// specified. This can appear anywhere in a type.
2082     Infer,
2083     /// Placeholder for a type that has failed to be defined.
2084     Err,
2085 }
2086
2087 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
2088 pub struct InlineAsmOutput {
2089     pub constraint: Symbol,
2090     pub is_rw: bool,
2091     pub is_indirect: bool,
2092     pub span: Span,
2093 }
2094
2095 // NOTE(eddyb) This is used within MIR as well, so unlike the rest of the HIR,
2096 // it needs to be `Clone` and use plain `Vec<T>` instead of `HirVec<T>`.
2097 #[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
2098 pub struct InlineAsm {
2099     pub asm: Symbol,
2100     pub asm_str_style: StrStyle,
2101     pub outputs: Vec<InlineAsmOutput>,
2102     pub inputs: Vec<Symbol>,
2103     pub clobbers: Vec<Symbol>,
2104     pub volatile: bool,
2105     pub alignstack: bool,
2106     pub dialect: AsmDialect,
2107 }
2108
2109 /// Represents a parameter in a function header.
2110 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2111 pub struct Param {
2112     pub attrs: HirVec<Attribute>,
2113     pub hir_id: HirId,
2114     pub pat: P<Pat>,
2115     pub span: Span,
2116 }
2117
2118 /// Represents the header (not the body) of a function declaration.
2119 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2120 pub struct FnDecl {
2121     /// The types of the function's parameters.
2122     ///
2123     /// Additional argument data is stored in the function's [body](Body::parameters).
2124     pub inputs: HirVec<Ty>,
2125     pub output: FunctionRetTy,
2126     pub c_variadic: bool,
2127     /// Does the function have an implicit self?
2128     pub implicit_self: ImplicitSelfKind,
2129 }
2130
2131 /// Represents what type of implicit self a function has, if any.
2132 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
2133 pub enum ImplicitSelfKind {
2134     /// Represents a `fn x(self);`.
2135     Imm,
2136     /// Represents a `fn x(mut self);`.
2137     Mut,
2138     /// Represents a `fn x(&self);`.
2139     ImmRef,
2140     /// Represents a `fn x(&mut self);`.
2141     MutRef,
2142     /// Represents when a function does not have a self argument or
2143     /// when a function has a `self: X` argument.
2144     None
2145 }
2146
2147 impl ImplicitSelfKind {
2148     /// Does this represent an implicit self?
2149     pub fn has_implicit_self(&self) -> bool {
2150         match *self {
2151             ImplicitSelfKind::None => false,
2152             _ => true,
2153         }
2154     }
2155 }
2156
2157 /// Is the trait definition an auto trait?
2158 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
2159 pub enum IsAuto {
2160     Yes,
2161     No
2162 }
2163
2164 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, HashStable,
2165          Ord, RustcEncodable, RustcDecodable, Debug)]
2166 pub enum IsAsync {
2167     Async,
2168     NotAsync,
2169 }
2170
2171 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, HashStable,
2172          RustcEncodable, RustcDecodable, Hash, Debug)]
2173 pub enum Unsafety {
2174     Unsafe,
2175     Normal,
2176 }
2177
2178 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
2179 pub enum Constness {
2180     Const,
2181     NotConst,
2182 }
2183
2184 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
2185 pub enum Defaultness {
2186     Default { has_value: bool },
2187     Final,
2188 }
2189
2190 impl Defaultness {
2191     pub fn has_value(&self) -> bool {
2192         match *self {
2193             Defaultness::Default { has_value, .. } => has_value,
2194             Defaultness::Final => true,
2195         }
2196     }
2197
2198     pub fn is_final(&self) -> bool {
2199         *self == Defaultness::Final
2200     }
2201
2202     pub fn is_default(&self) -> bool {
2203         match *self {
2204             Defaultness::Default { .. } => true,
2205             _ => false,
2206         }
2207     }
2208 }
2209
2210 impl fmt::Display for Unsafety {
2211     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2212         f.write_str(match self {
2213             Unsafety::Normal => "normal",
2214             Unsafety::Unsafe => "unsafe",
2215         })
2216     }
2217 }
2218
2219 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
2220 pub enum ImplPolarity {
2221     /// `impl Trait for Type`
2222     Positive,
2223     /// `impl !Trait for Type`
2224     Negative,
2225 }
2226
2227 impl fmt::Debug for ImplPolarity {
2228     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2229         f.write_str(match self {
2230             ImplPolarity::Positive => "positive",
2231             ImplPolarity::Negative => "negative",
2232         })
2233     }
2234 }
2235
2236
2237 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2238 pub enum FunctionRetTy {
2239     /// Return type is not specified.
2240     ///
2241     /// Functions default to `()` and
2242     /// closures default to inference. Span points to where return
2243     /// type would be inserted.
2244     DefaultReturn(Span),
2245     /// Everything else.
2246     Return(P<Ty>),
2247 }
2248
2249 impl fmt::Display for FunctionRetTy {
2250     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
2251         match self {
2252             Return(ref ty) => print::to_string(print::NO_ANN, |s| s.print_type(ty)).fmt(f),
2253             DefaultReturn(_) => "()".fmt(f),
2254         }
2255     }
2256 }
2257
2258 impl FunctionRetTy {
2259     pub fn span(&self) -> Span {
2260         match *self {
2261             DefaultReturn(span) => span,
2262             Return(ref ty) => ty.span,
2263         }
2264     }
2265 }
2266
2267 #[derive(RustcEncodable, RustcDecodable, Debug)]
2268 pub struct Mod {
2269     /// A span from the first token past `{` to the last token until `}`.
2270     /// For `mod foo;`, the inner span ranges from the first token
2271     /// to the last token in the external file.
2272     pub inner: Span,
2273     pub item_ids: HirVec<ItemId>,
2274 }
2275
2276 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2277 pub struct ForeignMod {
2278     pub abi: Abi,
2279     pub items: HirVec<ForeignItem>,
2280 }
2281
2282 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2283 pub struct GlobalAsm {
2284     pub asm: Symbol,
2285 }
2286
2287 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2288 pub struct EnumDef {
2289     pub variants: HirVec<Variant>,
2290 }
2291
2292 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2293 pub struct Variant {
2294     /// Name of the variant.
2295     #[stable_hasher(project(name))]
2296     pub ident: Ident,
2297     /// Attributes of the variant.
2298     pub attrs: HirVec<Attribute>,
2299     /// Id of the variant (not the constructor, see `VariantData::ctor_hir_id()`).
2300     pub id: HirId,
2301     /// Fields and constructor id of the variant.
2302     pub data: VariantData,
2303     /// Explicit discriminant (e.g., `Foo = 1`).
2304     pub disr_expr: Option<AnonConst>,
2305     /// Span
2306     pub span: Span
2307 }
2308
2309 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
2310 pub enum UseKind {
2311     /// One import, e.g., `use foo::bar` or `use foo::bar as baz`.
2312     /// Also produced for each element of a list `use`, e.g.
2313     /// `use foo::{a, b}` lowers to `use foo::a; use foo::b;`.
2314     Single,
2315
2316     /// Glob import, e.g., `use foo::*`.
2317     Glob,
2318
2319     /// Degenerate list import, e.g., `use foo::{a, b}` produces
2320     /// an additional `use foo::{}` for performing checks such as
2321     /// unstable feature gating. May be removed in the future.
2322     ListStem,
2323 }
2324
2325 /// References to traits in impls.
2326 ///
2327 /// `resolve` maps each `TraitRef`'s `ref_id` to its defining trait; that's all
2328 /// that the `ref_id` is for. Note that `ref_id`'s value is not the `HirId` of the
2329 /// trait being referred to but just a unique `HirId` that serves as a key
2330 /// within the resolution map.
2331 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2332 pub struct TraitRef {
2333     pub path: P<Path>,
2334     // Don't hash the `ref_id`. It is tracked via the thing it is used to access.
2335     #[stable_hasher(ignore)]
2336     pub hir_ref_id: HirId,
2337 }
2338
2339 impl TraitRef {
2340     /// Gets the `DefId` of the referenced trait. It _must_ actually be a trait or trait alias.
2341     pub fn trait_def_id(&self) -> DefId {
2342         match self.path.res {
2343             Res::Def(DefKind::Trait, did) => did,
2344             Res::Def(DefKind::TraitAlias, did) => did,
2345             Res::Err => {
2346                 FatalError.raise();
2347             }
2348             _ => unreachable!(),
2349         }
2350     }
2351 }
2352
2353 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2354 pub struct PolyTraitRef {
2355     /// The `'a` in `<'a> Foo<&'a T>`.
2356     pub bound_generic_params: HirVec<GenericParam>,
2357
2358     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`.
2359     pub trait_ref: TraitRef,
2360
2361     pub span: Span,
2362 }
2363
2364 pub type Visibility = Spanned<VisibilityKind>;
2365
2366 #[derive(RustcEncodable, RustcDecodable, Debug)]
2367 pub enum VisibilityKind {
2368     Public,
2369     Crate(CrateSugar),
2370     Restricted { path: P<Path>, hir_id: HirId },
2371     Inherited,
2372 }
2373
2374 impl VisibilityKind {
2375     pub fn is_pub(&self) -> bool {
2376         match *self {
2377             VisibilityKind::Public => true,
2378             _ => false
2379         }
2380     }
2381
2382     pub fn is_pub_restricted(&self) -> bool {
2383         match *self {
2384             VisibilityKind::Public |
2385             VisibilityKind::Inherited => false,
2386             VisibilityKind::Crate(..) |
2387             VisibilityKind::Restricted { .. } => true,
2388         }
2389     }
2390
2391     pub fn descr(&self) -> &'static str {
2392         match *self {
2393             VisibilityKind::Public => "public",
2394             VisibilityKind::Inherited => "private",
2395             VisibilityKind::Crate(..) => "crate-visible",
2396             VisibilityKind::Restricted { .. } => "restricted",
2397         }
2398     }
2399 }
2400
2401 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2402 pub struct StructField {
2403     pub span: Span,
2404     #[stable_hasher(project(name))]
2405     pub ident: Ident,
2406     pub vis: Visibility,
2407     pub hir_id: HirId,
2408     pub ty: P<Ty>,
2409     pub attrs: HirVec<Attribute>,
2410 }
2411
2412 impl StructField {
2413     // Still necessary in couple of places
2414     pub fn is_positional(&self) -> bool {
2415         let first = self.ident.as_str().as_bytes()[0];
2416         first >= b'0' && first <= b'9'
2417     }
2418 }
2419
2420 /// Fields and constructor IDs of enum variants and structs.
2421 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2422 pub enum VariantData {
2423     /// A struct variant.
2424     ///
2425     /// E.g., `Bar { .. }` as in `enum Foo { Bar { .. } }`.
2426     Struct(HirVec<StructField>, /* recovered */ bool),
2427     /// A tuple variant.
2428     ///
2429     /// E.g., `Bar(..)` as in `enum Foo { Bar(..) }`.
2430     Tuple(HirVec<StructField>, HirId),
2431     /// A unit variant.
2432     ///
2433     /// E.g., `Bar = ..` as in `enum Foo { Bar = .. }`.
2434     Unit(HirId),
2435 }
2436
2437 impl VariantData {
2438     /// Return the fields of this variant.
2439     pub fn fields(&self) -> &[StructField] {
2440         match *self {
2441             VariantData::Struct(ref fields, ..) | VariantData::Tuple(ref fields, ..) => fields,
2442             _ => &[],
2443         }
2444     }
2445
2446     /// Return the `HirId` of this variant's constructor, if it has one.
2447     pub fn ctor_hir_id(&self) -> Option<HirId> {
2448         match *self {
2449             VariantData::Struct(_, _) => None,
2450             VariantData::Tuple(_, hir_id) | VariantData::Unit(hir_id) => Some(hir_id),
2451         }
2452     }
2453 }
2454
2455 // The bodies for items are stored "out of line", in a separate
2456 // hashmap in the `Crate`. Here we just record the node-id of the item
2457 // so it can fetched later.
2458 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug)]
2459 pub struct ItemId {
2460     pub id: HirId,
2461 }
2462
2463 /// An item
2464 ///
2465 /// The name might be a dummy name in case of anonymous items
2466 #[derive(RustcEncodable, RustcDecodable, Debug)]
2467 pub struct Item {
2468     pub ident: Ident,
2469     pub hir_id: HirId,
2470     pub attrs: HirVec<Attribute>,
2471     pub kind: ItemKind,
2472     pub vis: Visibility,
2473     pub span: Span,
2474 }
2475
2476 #[derive(Copy, Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
2477 pub struct FnHeader {
2478     pub unsafety: Unsafety,
2479     pub constness: Constness,
2480     pub asyncness: IsAsync,
2481     pub abi: Abi,
2482 }
2483
2484 impl FnHeader {
2485     pub fn is_const(&self) -> bool {
2486         match &self.constness {
2487             Constness::Const => true,
2488             _ => false,
2489         }
2490     }
2491 }
2492
2493 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2494 pub enum ItemKind {
2495     /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
2496     ///
2497     /// E.g., `extern crate foo` or `extern crate foo_bar as foo`.
2498     ExternCrate(Option<Name>),
2499
2500     /// `use foo::bar::*;` or `use foo::bar::baz as quux;`
2501     ///
2502     /// or just
2503     ///
2504     /// `use foo::bar::baz;` (with `as baz` implicitly on the right).
2505     Use(P<Path>, UseKind),
2506
2507     /// A `static` item.
2508     Static(P<Ty>, Mutability, BodyId),
2509     /// A `const` item.
2510     Const(P<Ty>, BodyId),
2511     /// A function declaration.
2512     Fn(P<FnDecl>, FnHeader, Generics, BodyId),
2513     /// A module.
2514     Mod(Mod),
2515     /// An external module, e.g. `extern { .. }`.
2516     ForeignMod(ForeignMod),
2517     /// Module-level inline assembly (from `global_asm!`).
2518     GlobalAsm(P<GlobalAsm>),
2519     /// A type alias, e.g., `type Foo = Bar<u8>`.
2520     TyAlias(P<Ty>, Generics),
2521     /// An opaque `impl Trait` type alias, e.g., `type Foo = impl Bar;`.
2522     OpaqueTy(OpaqueTy),
2523     /// An enum definition, e.g., `enum Foo<A, B> {C<A>, D<B>}`.
2524     Enum(EnumDef, Generics),
2525     /// A struct definition, e.g., `struct Foo<A> {x: A}`.
2526     Struct(VariantData, Generics),
2527     /// A union definition, e.g., `union Foo<A, B> {x: A, y: B}`.
2528     Union(VariantData, Generics),
2529     /// A trait definition.
2530     Trait(IsAuto, Unsafety, Generics, GenericBounds, HirVec<TraitItemRef>),
2531     /// A trait alias.
2532     TraitAlias(Generics, GenericBounds),
2533
2534     /// An implementation, e.g., `impl<A> Trait for Foo { .. }`.
2535     Impl(Unsafety,
2536          ImplPolarity,
2537          Defaultness,
2538          Generics,
2539          Option<TraitRef>, // (optional) trait this impl implements
2540          P<Ty>, // self
2541          HirVec<ImplItemRef>),
2542 }
2543
2544 impl ItemKind {
2545     pub fn descriptive_variant(&self) -> &str {
2546         match *self {
2547             ItemKind::ExternCrate(..) => "extern crate",
2548             ItemKind::Use(..) => "use",
2549             ItemKind::Static(..) => "static item",
2550             ItemKind::Const(..) => "constant item",
2551             ItemKind::Fn(..) => "function",
2552             ItemKind::Mod(..) => "module",
2553             ItemKind::ForeignMod(..) => "foreign module",
2554             ItemKind::GlobalAsm(..) => "global asm",
2555             ItemKind::TyAlias(..) => "type alias",
2556             ItemKind::OpaqueTy(..) => "opaque type",
2557             ItemKind::Enum(..) => "enum",
2558             ItemKind::Struct(..) => "struct",
2559             ItemKind::Union(..) => "union",
2560             ItemKind::Trait(..) => "trait",
2561             ItemKind::TraitAlias(..) => "trait alias",
2562             ItemKind::Impl(..) => "impl",
2563         }
2564     }
2565
2566     pub fn adt_kind(&self) -> Option<AdtKind> {
2567         match *self {
2568             ItemKind::Struct(..) => Some(AdtKind::Struct),
2569             ItemKind::Union(..) => Some(AdtKind::Union),
2570             ItemKind::Enum(..) => Some(AdtKind::Enum),
2571             _ => None,
2572         }
2573     }
2574
2575     pub fn generics(&self) -> Option<&Generics> {
2576         Some(match *self {
2577             ItemKind::Fn(_, _, ref generics, _) |
2578             ItemKind::TyAlias(_, ref generics) |
2579             ItemKind::OpaqueTy(OpaqueTy { ref generics, impl_trait_fn: None, .. }) |
2580             ItemKind::Enum(_, ref generics) |
2581             ItemKind::Struct(_, ref generics) |
2582             ItemKind::Union(_, ref generics) |
2583             ItemKind::Trait(_, _, ref generics, _, _) |
2584             ItemKind::Impl(_, _, _, ref generics, _, _, _)=> generics,
2585             _ => return None
2586         })
2587     }
2588 }
2589
2590 /// A reference from an trait to one of its associated items. This
2591 /// contains the item's id, naturally, but also the item's name and
2592 /// some other high-level details (like whether it is an associated
2593 /// type or method, and whether it is public). This allows other
2594 /// passes to find the impl they want without loading the ID (which
2595 /// means fewer edges in the incremental compilation graph).
2596 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2597 pub struct TraitItemRef {
2598     pub id: TraitItemId,
2599     #[stable_hasher(project(name))]
2600     pub ident: Ident,
2601     pub kind: AssocItemKind,
2602     pub span: Span,
2603     pub defaultness: Defaultness,
2604 }
2605
2606 /// A reference from an impl to one of its associated items. This
2607 /// contains the item's ID, naturally, but also the item's name and
2608 /// some other high-level details (like whether it is an associated
2609 /// type or method, and whether it is public). This allows other
2610 /// passes to find the impl they want without loading the ID (which
2611 /// means fewer edges in the incremental compilation graph).
2612 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2613 pub struct ImplItemRef {
2614     pub id: ImplItemId,
2615     #[stable_hasher(project(name))]
2616     pub ident: Ident,
2617     pub kind: AssocItemKind,
2618     pub span: Span,
2619     pub vis: Visibility,
2620     pub defaultness: Defaultness,
2621 }
2622
2623 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, Debug, HashStable)]
2624 pub enum AssocItemKind {
2625     Const,
2626     Method { has_self: bool },
2627     Type,
2628     OpaqueTy,
2629 }
2630
2631 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2632 pub struct ForeignItem {
2633     #[stable_hasher(project(name))]
2634     pub ident: Ident,
2635     pub attrs: HirVec<Attribute>,
2636     pub kind: ForeignItemKind,
2637     pub hir_id: HirId,
2638     pub span: Span,
2639     pub vis: Visibility,
2640 }
2641
2642 /// An item within an `extern` block.
2643 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
2644 pub enum ForeignItemKind {
2645     /// A foreign function.
2646     Fn(P<FnDecl>, HirVec<Ident>, Generics),
2647     /// A foreign static item (`static ext: u8`).
2648     Static(P<Ty>, Mutability),
2649     /// A foreign type.
2650     Type,
2651 }
2652
2653 impl ForeignItemKind {
2654     pub fn descriptive_variant(&self) -> &str {
2655         match *self {
2656             ForeignItemKind::Fn(..) => "foreign function",
2657             ForeignItemKind::Static(..) => "foreign static item",
2658             ForeignItemKind::Type => "foreign type",
2659         }
2660     }
2661 }
2662
2663 /// A variable captured by a closure.
2664 #[derive(Debug, Copy, Clone, RustcEncodable, RustcDecodable, HashStable)]
2665 pub struct Upvar {
2666     // First span where it is accessed (there can be multiple).
2667     pub span: Span
2668 }
2669
2670 pub type CaptureModeMap = NodeMap<CaptureClause>;
2671
2672  // The TraitCandidate's import_ids is empty if the trait is defined in the same module, and
2673  // has length > 0 if the trait is found through an chain of imports, starting with the
2674  // import/use statement in the scope where the trait is used.
2675 #[derive(Clone, Debug)]
2676 pub struct TraitCandidate {
2677     pub def_id: DefId,
2678     pub import_ids: SmallVec<[NodeId; 1]>,
2679 }
2680
2681 // Trait method resolution
2682 pub type TraitMap = NodeMap<Vec<TraitCandidate>>;
2683
2684 // Map from the NodeId of a glob import to a list of items which are actually
2685 // imported.
2686 pub type GlobMap = NodeMap<FxHashSet<Name>>;
2687
2688 pub fn provide(providers: &mut Providers<'_>) {
2689     check_attr::provide(providers);
2690     map::provide(providers);
2691     upvars::provide(providers);
2692 }
2693
2694 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
2695 pub struct CodegenFnAttrs {
2696     pub flags: CodegenFnAttrFlags,
2697     /// Parsed representation of the `#[inline]` attribute
2698     pub inline: InlineAttr,
2699     /// Parsed representation of the `#[optimize]` attribute
2700     pub optimize: OptimizeAttr,
2701     /// The `#[export_name = "..."]` attribute, indicating a custom symbol a
2702     /// function should be exported under
2703     pub export_name: Option<Symbol>,
2704     /// The `#[link_name = "..."]` attribute, indicating a custom symbol an
2705     /// imported function should be imported as. Note that `export_name`
2706     /// probably isn't set when this is set, this is for foreign items while
2707     /// `#[export_name]` is for Rust-defined functions.
2708     pub link_name: Option<Symbol>,
2709     /// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an
2710     /// imported function has in the dynamic library. Note that this must not
2711     /// be set when `link_name` is set. This is for foreign items with the
2712     /// "raw-dylib" kind.
2713     pub link_ordinal: Option<usize>,
2714     /// The `#[target_feature(enable = "...")]` attribute and the enabled
2715     /// features (only enabled features are supported right now).
2716     pub target_features: Vec<Symbol>,
2717     /// The `#[linkage = "..."]` attribute and the value we found.
2718     pub linkage: Option<Linkage>,
2719     /// The `#[link_section = "..."]` attribute, or what executable section this
2720     /// should be placed in.
2721     pub link_section: Option<Symbol>,
2722 }
2723
2724 bitflags! {
2725     #[derive(RustcEncodable, RustcDecodable, HashStable)]
2726     pub struct CodegenFnAttrFlags: u32 {
2727         /// `#[cold]`: a hint to LLVM that this function, when called, is never on
2728         /// the hot path.
2729         const COLD                      = 1 << 0;
2730         /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
2731         /// function is never null.
2732         const ALLOCATOR                 = 1 << 1;
2733         /// `#[unwind]`: an indicator that this function may unwind despite what
2734         /// its ABI signature may otherwise imply.
2735         const UNWIND                    = 1 << 2;
2736         /// `#[rust_allocator_nounwind]`, an indicator that an imported FFI
2737         /// function will never unwind. Probably obsolete by recent changes with
2738         /// #[unwind], but hasn't been removed/migrated yet
2739         const RUSTC_ALLOCATOR_NOUNWIND  = 1 << 3;
2740         /// `#[naked]`: an indicator to LLVM that no function prologue/epilogue
2741         /// should be generated.
2742         const NAKED                     = 1 << 4;
2743         /// `#[no_mangle]`: an indicator that the function's name should be the same
2744         /// as its symbol.
2745         const NO_MANGLE                 = 1 << 5;
2746         /// `#[rustc_std_internal_symbol]`: an indicator that this symbol is a
2747         /// "weird symbol" for the standard library in that it has slightly
2748         /// different linkage, visibility, and reachability rules.
2749         const RUSTC_STD_INTERNAL_SYMBOL = 1 << 6;
2750         /// `#[no_debug]`: an indicator that no debugging information should be
2751         /// generated for this function by LLVM.
2752         const NO_DEBUG                  = 1 << 7;
2753         /// `#[thread_local]`: indicates a static is actually a thread local
2754         /// piece of memory
2755         const THREAD_LOCAL              = 1 << 8;
2756         /// `#[used]`: indicates that LLVM can't eliminate this function (but the
2757         /// linker can!).
2758         const USED                      = 1 << 9;
2759         /// `#[ffi_returns_twice]`, indicates that an extern function can return
2760         /// multiple times
2761         const FFI_RETURNS_TWICE         = 1 << 10;
2762         /// `#[track_caller]`: allow access to the caller location
2763         const TRACK_CALLER              = 1 << 11;
2764     }
2765 }
2766
2767 impl CodegenFnAttrs {
2768     pub fn new() -> CodegenFnAttrs {
2769         CodegenFnAttrs {
2770             flags: CodegenFnAttrFlags::empty(),
2771             inline: InlineAttr::None,
2772             optimize: OptimizeAttr::None,
2773             export_name: None,
2774             link_name: None,
2775             link_ordinal: None,
2776             target_features: vec![],
2777             linkage: None,
2778             link_section: None,
2779         }
2780     }
2781
2782     /// Returns `true` if `#[inline]` or `#[inline(always)]` is present.
2783     pub fn requests_inline(&self) -> bool {
2784         match self.inline {
2785             InlineAttr::Hint | InlineAttr::Always => true,
2786             InlineAttr::None | InlineAttr::Never => false,
2787         }
2788     }
2789
2790     /// Returns `true` if it looks like this symbol needs to be exported, for example:
2791     ///
2792     /// * `#[no_mangle]` is present
2793     /// * `#[export_name(...)]` is present
2794     /// * `#[linkage]` is present
2795     pub fn contains_extern_indicator(&self) -> bool {
2796         self.flags.contains(CodegenFnAttrFlags::NO_MANGLE) ||
2797             self.export_name.is_some() ||
2798             match self.linkage {
2799                 // These are private, so make sure we don't try to consider
2800                 // them external.
2801                 None |
2802                 Some(Linkage::Internal) |
2803                 Some(Linkage::Private) => false,
2804                 Some(_) => true,
2805             }
2806     }
2807 }
2808
2809 #[derive(Copy, Clone, Debug)]
2810 pub enum Node<'hir> {
2811     Param(&'hir Param),
2812     Item(&'hir Item),
2813     ForeignItem(&'hir ForeignItem),
2814     TraitItem(&'hir TraitItem),
2815     ImplItem(&'hir ImplItem),
2816     Variant(&'hir Variant),
2817     Field(&'hir StructField),
2818     AnonConst(&'hir AnonConst),
2819     Expr(&'hir Expr),
2820     Stmt(&'hir Stmt),
2821     PathSegment(&'hir PathSegment),
2822     Ty(&'hir Ty),
2823     TraitRef(&'hir TraitRef),
2824     Binding(&'hir Pat),
2825     Pat(&'hir Pat),
2826     Arm(&'hir Arm),
2827     Block(&'hir Block),
2828     Local(&'hir Local),
2829     MacroDef(&'hir MacroDef),
2830
2831     /// `Ctor` refers to the constructor of an enum variant or struct. Only tuple or unit variants
2832     /// with synthesized constructors.
2833     Ctor(&'hir VariantData),
2834
2835     Lifetime(&'hir Lifetime),
2836     GenericParam(&'hir GenericParam),
2837     Visibility(&'hir Visibility),
2838
2839     Crate,
2840 }
2841
2842 impl Node<'_> {
2843     pub fn ident(&self) -> Option<Ident> {
2844         match self {
2845             Node::TraitItem(TraitItem { ident, .. }) |
2846             Node::ImplItem(ImplItem { ident, .. }) |
2847             Node::ForeignItem(ForeignItem { ident, .. }) |
2848             Node::Item(Item { ident, .. }) => Some(*ident),
2849             _ => None,
2850         }
2851     }
2852 }