src/librustc/ty/structural_impls.rs

   1 //! This module contains implements of the `Lift` and `TypeFoldable`
   2 //! traits for various types in the Rust compiler. Most are written by
   3 //! hand, though we've recently added some macros (e.g.,
   4 //! `BraceStructLiftImpl!`) to help with the tedium.
   5
   6 use crate::hir::def::Namespace;
   7 use crate::mir::ProjectionKind;
   8 use crate::mir::interpret::ConstValue;
   9 use crate::ty::{self, Lift, Ty, TyCtxt, InferConst};
  10 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
  11 use crate::ty::print::{FmtPrinter, Printer};
  12 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
  13 use smallvec::SmallVec;
  14 use crate::mir::interpret;
  15
  16 use std::fmt;
  17 use std::rc::Rc;
  18
  19 impl fmt::Debug for ty::GenericParamDef {
  20     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  21         let type_name = match self.kind {
  22             ty::GenericParamDefKind::Lifetime => "Lifetime",
  23             ty::GenericParamDefKind::Type {..} => "Type",
  24             ty::GenericParamDefKind::Const => "Const",
  25         };
  26         write!(f, "{}({}, {:?}, {})",
  27                type_name,
  28                self.name,
  29                self.def_id,
  30                self.index)
  31     }
  32 }
  33
  34 impl fmt::Debug for ty::TraitDef {
  35     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  36         ty::tls::with(|tcx| {
  37             FmtPrinter::new(tcx, f, Namespace::TypeNS)
  38                 .print_def_path(self.def_id, &[])?;
  39             Ok(())
  40         })
  41     }
  42 }
  43
  44 impl fmt::Debug for ty::AdtDef {
  45     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  46         ty::tls::with(|tcx| {
  47             FmtPrinter::new(tcx, f, Namespace::TypeNS)
  48                 .print_def_path(self.did, &[])?;
  49             Ok(())
  50         })
  51     }
  52 }
  53
  54 impl fmt::Debug for ty::ClosureUpvar<'tcx> {
  55     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  56         write!(f, "ClosureUpvar({:?},{:?})",
  57                self.res,
  58                self.ty)
  59     }
  60 }
  61
  62 impl fmt::Debug for ty::UpvarId {
  63     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  64         let name = ty::tls::with(|tcx| {
  65             tcx.hir().name_by_hir_id(self.var_path.hir_id)
  66         });
  67         write!(f, "UpvarId({:?};`{}`;{:?})",
  68             self.var_path.hir_id,
  69             name,
  70             self.closure_expr_id)
  71     }
  72 }
  73
  74 impl fmt::Debug for ty::UpvarBorrow<'tcx> {
  75     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  76         write!(f, "UpvarBorrow({:?}, {:?})",
  77                self.kind, self.region)
  78     }
  79 }
  80
  81 impl fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  82     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  83         fmt::Display::fmt(self, f)
  84     }
  85 }
  86
  87 impl fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  88     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  89         write!(f, "{:?} -> {}", self.kind, self.target)
  90     }
  91 }
  92
  93 impl fmt::Debug for ty::BoundRegion {
  94     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  95         match *self {
  96             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  97             ty::BrFresh(n) => write!(f, "BrFresh({:?})", n),
  98             ty::BrNamed(did, name) => {
  99                 write!(f, "BrNamed({:?}:{:?}, {})",
 100                         did.krate, did.index, name)
 101             }
 102             ty::BrEnv => write!(f, "BrEnv"),
 103         }
 104     }
 105 }
 106
 107 impl fmt::Debug for ty::RegionKind {
 108     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 109         match *self {
 110             ty::ReEarlyBound(ref data) => {
 111                 write!(f, "ReEarlyBound({}, {})",
 112                         data.index,
 113                         data.name)
 114             }
 115
 116             ty::ReClosureBound(ref vid) => {
 117                 write!(f, "ReClosureBound({:?})", vid)
 118             }
 119
 120             ty::ReLateBound(binder_id, ref bound_region) => {
 121                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
 122             }
 123
 124             ty::ReFree(ref fr) => fr.fmt(f),
 125
 126             ty::ReScope(id) => write!(f, "ReScope({:?})", id),
 127
 128             ty::ReStatic => write!(f, "ReStatic"),
 129
 130             ty::ReVar(ref vid) => vid.fmt(f),
 131
 132             ty::RePlaceholder(placeholder) => {
 133                 write!(f, "RePlaceholder({:?})", placeholder)
 134             }
 135
 136             ty::ReEmpty => write!(f, "ReEmpty"),
 137
 138             ty::ReErased => write!(f, "ReErased"),
 139         }
 140     }
 141 }
 142
 143 impl fmt::Debug for ty::FreeRegion {
 144     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 145         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 146     }
 147 }
 148
 149 impl fmt::Debug for ty::Variance {
 150     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 151         f.write_str(match *self {
 152             ty::Covariant => "+",
 153             ty::Contravariant => "-",
 154             ty::Invariant => "o",
 155             ty::Bivariant => "*",
 156         })
 157     }
 158 }
 159
 160 impl fmt::Debug for ty::FnSig<'tcx> {
 161     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 162         write!(f, "({:?}; c_variadic: {})->{:?}",
 163                 self.inputs(), self.c_variadic, self.output())
 164     }
 165 }
 166
 167 impl fmt::Debug for ty::TyVid {
 168     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 169         write!(f, "_#{}t", self.index)
 170     }
 171 }
 172
 173 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 174     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 175         write!(f, "_#{}c", self.index)
 176     }
 177 }
 178
 179 impl fmt::Debug for ty::IntVid {
 180     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 181         write!(f, "_#{}i", self.index)
 182     }
 183 }
 184
 185 impl fmt::Debug for ty::FloatVid {
 186     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 187         write!(f, "_#{}f", self.index)
 188     }
 189 }
 190
 191 impl fmt::Debug for ty::RegionVid {
 192     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 193         write!(f, "'_#{}r", self.index())
 194     }
 195 }
 196
 197 impl fmt::Debug for ty::InferTy {
 198     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 199         match *self {
 200             ty::TyVar(ref v) => v.fmt(f),
 201             ty::IntVar(ref v) => v.fmt(f),
 202             ty::FloatVar(ref v) => v.fmt(f),
 203             ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
 204             ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
 205             ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v),
 206         }
 207     }
 208 }
 209
 210 impl fmt::Debug for ty::IntVarValue {
 211     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 212         match *self {
 213             ty::IntType(ref v) => v.fmt(f),
 214             ty::UintType(ref v) => v.fmt(f),
 215         }
 216     }
 217 }
 218
 219 impl fmt::Debug for ty::FloatVarValue {
 220     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 221         self.0.fmt(f)
 222     }
 223 }
 224
 225 impl fmt::Debug for ty::TraitRef<'tcx> {
 226     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 227         // FIXME(#59188) this is used across the compiler to print
 228         // a `TraitRef` qualified (with the Self type explicit),
 229         // instead of having a different way to make that choice.
 230         write!(f, "<{} as {}>", self.self_ty(), self)
 231     }
 232 }
 233
 234 impl fmt::Debug for Ty<'tcx> {
 235     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 236         fmt::Display::fmt(self, f)
 237     }
 238 }
 239
 240 impl fmt::Debug for ty::ParamTy {
 241     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 242         write!(f, "{}/#{}", self.name, self.index)
 243     }
 244 }
 245
 246 impl fmt::Debug for ty::ParamConst {
 247     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 248         write!(f, "{}/#{}", self.name, self.index)
 249     }
 250 }
 251
 252 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 253     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 254         write!(f, "TraitPredicate({:?})", self.trait_ref)
 255     }
 256 }
 257
 258 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 259     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 260         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 261     }
 262 }
 263
 264 impl fmt::Debug for ty::Predicate<'tcx> {
 265     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 266         match *self {
 267             ty::Predicate::Trait(ref a) => a.fmt(f),
 268             ty::Predicate::Subtype(ref pair) => pair.fmt(f),
 269             ty::Predicate::RegionOutlives(ref pair) => pair.fmt(f),
 270             ty::Predicate::TypeOutlives(ref pair) => pair.fmt(f),
 271             ty::Predicate::Projection(ref pair) => pair.fmt(f),
 272             ty::Predicate::WellFormed(ty) => write!(f, "WellFormed({:?})", ty),
 273             ty::Predicate::ObjectSafe(trait_def_id) => {
 274                 write!(f, "ObjectSafe({:?})", trait_def_id)
 275             }
 276             ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
 277                 write!(f, "ClosureKind({:?}, {:?}, {:?})",
 278                     closure_def_id, closure_substs, kind)
 279             }
 280             ty::Predicate::ConstEvaluatable(def_id, substs) => {
 281                 write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
 282             }
 283         }
 284     }
 285 }
 286
 287 ///////////////////////////////////////////////////////////////////////////
 288 // Atomic structs
 289 //
 290 // For things that don't carry any arena-allocated data (and are
 291 // copy...), just add them to this list.
 292
 293 CloneTypeFoldableAndLiftImpls! {
 294     (),
 295     bool,
 296     usize,
 297     crate::ty::layout::VariantIdx,
 298     u64,
 299     String,
 300     crate::middle::region::Scope,
 301     ::syntax::ast::FloatTy,
 302     ::syntax::ast::NodeId,
 303     ::syntax_pos::symbol::Symbol,
 304     crate::hir::def::Res,
 305     crate::hir::def_id::DefId,
 306     crate::hir::InlineAsm,
 307     crate::hir::MatchSource,
 308     crate::hir::Mutability,
 309     crate::hir::Unsafety,
 310     ::rustc_target::spec::abi::Abi,
 311     crate::mir::Local,
 312     crate::mir::Promoted,
 313     crate::traits::Reveal,
 314     crate::ty::adjustment::AutoBorrowMutability,
 315     crate::ty::AdtKind,
 316     // Including `BoundRegion` is a *bit* dubious, but direct
 317     // references to bound region appear in `ty::Error`, and aren't
 318     // really meant to be folded. In general, we can only fold a fully
 319     // general `Region`.
 320     crate::ty::BoundRegion,
 321     crate::ty::Placeholder<crate::ty::BoundRegion>,
 322     crate::ty::ClosureKind,
 323     crate::ty::FreeRegion,
 324     crate::ty::InferTy,
 325     crate::ty::IntVarValue,
 326     crate::ty::ParamConst,
 327     crate::ty::ParamTy,
 328     crate::ty::adjustment::PointerCast,
 329     crate::ty::RegionVid,
 330     crate::ty::UniverseIndex,
 331     crate::ty::Variance,
 332     ::syntax_pos::Span,
 333 }
 334
 335 ///////////////////////////////////////////////////////////////////////////
 336 // Lift implementations
 337
 338 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 339 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 340     type Lifted = (A::Lifted, B::Lifted);
 341     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 342         tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b)))
 343     }
 344 }
 345
 346 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 347     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 348     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 349         tcx.lift(&self.0).and_then(|a| {
 350             tcx.lift(&self.1).and_then(|b| tcx.lift(&self.2).map(|c| (a, b, c)))
 351         })
 352     }
 353 }
 354
 355 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 356     type Lifted = Option<T::Lifted>;
 357     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 358         match *self {
 359             Some(ref x) => tcx.lift(x).map(Some),
 360             None => Some(None)
 361         }
 362     }
 363 }
 364
 365 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 366     type Lifted = Result<T::Lifted, E::Lifted>;
 367     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 368         match *self {
 369             Ok(ref x) => tcx.lift(x).map(Ok),
 370             Err(ref e) => tcx.lift(e).map(Err)
 371         }
 372     }
 373 }
 374
 375 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 376     type Lifted = Box<T::Lifted>;
 377     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 378         tcx.lift(&**self).map(Box::new)
 379     }
 380 }
 381
 382 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] {
 383     type Lifted = Vec<T::Lifted>;
 384     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 385         // type annotation needed to inform `projection_must_outlive`
 386         let mut result : Vec<<T as Lift<'tcx>>::Lifted>
 387             = Vec::with_capacity(self.len());
 388         for x in self {
 389             if let Some(value) = tcx.lift(x) {
 390                 result.push(value);
 391             } else {
 392                 return None;
 393             }
 394         }
 395         Some(result)
 396     }
 397 }
 398
 399 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 400     type Lifted = Vec<T::Lifted>;
 401     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 402         tcx.lift(&self[..])
 403     }
 404 }
 405
 406 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 407     type Lifted = IndexVec<I, T::Lifted>;
 408     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 409         self.iter()
 410             .map(|e| tcx.lift(e))
 411             .collect()
 412     }
 413 }
 414
 415 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 416     type Lifted = ty::TraitRef<'tcx>;
 417     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 418         tcx.lift(&self.substs).map(|substs| ty::TraitRef {
 419             def_id: self.def_id,
 420             substs,
 421         })
 422     }
 423 }
 424
 425 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 426     type Lifted = ty::ExistentialTraitRef<'tcx>;
 427     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 428         tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef {
 429             def_id: self.def_id,
 430             substs,
 431         })
 432     }
 433 }
 434
 435 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 436     type Lifted = ty::ExistentialPredicate<'tcx>;
 437     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 438         match self {
 439             ty::ExistentialPredicate::Trait(x) => {
 440                 tcx.lift(x).map(ty::ExistentialPredicate::Trait)
 441             }
 442             ty::ExistentialPredicate::Projection(x) => {
 443                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 444             }
 445             ty::ExistentialPredicate::AutoTrait(def_id) => {
 446                 Some(ty::ExistentialPredicate::AutoTrait(*def_id))
 447             }
 448         }
 449     }
 450 }
 451
 452 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 453     type Lifted = ty::TraitPredicate<'tcx>;
 454     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 455                              -> Option<ty::TraitPredicate<'tcx>> {
 456         tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 457             trait_ref,
 458         })
 459     }
 460 }
 461
 462 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 463     type Lifted = ty::SubtypePredicate<'tcx>;
 464     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 465                              -> Option<ty::SubtypePredicate<'tcx>> {
 466         tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 467             a_is_expected: self.a_is_expected,
 468             a,
 469             b,
 470         })
 471     }
 472 }
 473
 474 impl<'tcx, A: Copy+Lift<'tcx>, B: Copy+Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 475     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 476     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 477         tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 478     }
 479 }
 480
 481 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 482     type Lifted = ty::ProjectionTy<'tcx>;
 483     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 484                              -> Option<ty::ProjectionTy<'tcx>> {
 485         tcx.lift(&self.substs).map(|substs| {
 486             ty::ProjectionTy {
 487                 item_def_id: self.item_def_id,
 488                 substs,
 489             }
 490         })
 491     }
 492 }
 493
 494 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 495     type Lifted = ty::ProjectionPredicate<'tcx>;
 496     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 497                              -> Option<ty::ProjectionPredicate<'tcx>> {
 498         tcx.lift(&(self.projection_ty, self.ty)).map(|(projection_ty, ty)| {
 499             ty::ProjectionPredicate {
 500                 projection_ty,
 501                 ty,
 502             }
 503         })
 504     }
 505 }
 506
 507 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 508     type Lifted = ty::ExistentialProjection<'tcx>;
 509     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 510         tcx.lift(&self.substs).map(|substs| {
 511             ty::ExistentialProjection {
 512                 substs,
 513                 ty: tcx.lift(&self.ty).expect("type must lift when substs do"),
 514                 item_def_id: self.item_def_id,
 515             }
 516         })
 517     }
 518 }
 519
 520 impl<'a, 'tcx> Lift<'tcx> for ty::Predicate<'a> {
 521     type Lifted = ty::Predicate<'tcx>;
 522     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 523         match *self {
 524             ty::Predicate::Trait(ref binder) => {
 525                 tcx.lift(binder).map(ty::Predicate::Trait)
 526             }
 527             ty::Predicate::Subtype(ref binder) => {
 528                 tcx.lift(binder).map(ty::Predicate::Subtype)
 529             }
 530             ty::Predicate::RegionOutlives(ref binder) => {
 531                 tcx.lift(binder).map(ty::Predicate::RegionOutlives)
 532             }
 533             ty::Predicate::TypeOutlives(ref binder) => {
 534                 tcx.lift(binder).map(ty::Predicate::TypeOutlives)
 535             }
 536             ty::Predicate::Projection(ref binder) => {
 537                 tcx.lift(binder).map(ty::Predicate::Projection)
 538             }
 539             ty::Predicate::WellFormed(ty) => {
 540                 tcx.lift(&ty).map(ty::Predicate::WellFormed)
 541             }
 542             ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
 543                 tcx.lift(&closure_substs)
 544                    .map(|closure_substs| ty::Predicate::ClosureKind(closure_def_id,
 545                                                                     closure_substs,
 546                                                                     kind))
 547             }
 548             ty::Predicate::ObjectSafe(trait_def_id) => {
 549                 Some(ty::Predicate::ObjectSafe(trait_def_id))
 550             }
 551             ty::Predicate::ConstEvaluatable(def_id, substs) => {
 552                 tcx.lift(&substs).map(|substs| {
 553                     ty::Predicate::ConstEvaluatable(def_id, substs)
 554                 })
 555             }
 556         }
 557     }
 558 }
 559
 560 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> {
 561     type Lifted = ty::Binder<T::Lifted>;
 562     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 563         tcx.lift(self.skip_binder()).map(ty::Binder::bind)
 564     }
 565 }
 566
 567 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 568     type Lifted = ty::ParamEnv<'tcx>;
 569     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 570         tcx.lift(&self.caller_bounds).map(|caller_bounds| {
 571             ty::ParamEnv {
 572                 reveal: self.reveal,
 573                 caller_bounds,
 574                 def_id: self.def_id,
 575             }
 576         })
 577     }
 578 }
 579
 580 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 581     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 582     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 583         tcx.lift(&self.param_env).and_then(|param_env| {
 584             tcx.lift(&self.value).map(|value| {
 585                 ty::ParamEnvAnd {
 586                     param_env,
 587                     value,
 588                 }
 589             })
 590         })
 591     }
 592 }
 593
 594 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 595     type Lifted = ty::ClosureSubsts<'tcx>;
 596     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 597         tcx.lift(&self.substs).map(|substs| {
 598             ty::ClosureSubsts { substs }
 599         })
 600     }
 601 }
 602
 603 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 604     type Lifted = ty::GeneratorSubsts<'tcx>;
 605     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 606         tcx.lift(&self.substs).map(|substs| {
 607             ty::GeneratorSubsts { substs }
 608         })
 609     }
 610 }
 611
 612 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 613     type Lifted = ty::adjustment::Adjustment<'tcx>;
 614     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 615         tcx.lift(&self.kind).and_then(|kind| {
 616             tcx.lift(&self.target).map(|target| {
 617                 ty::adjustment::Adjustment { kind, target }
 618             })
 619         })
 620     }
 621 }
 622
 623 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 624     type Lifted = ty::adjustment::Adjust<'tcx>;
 625     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 626         match *self {
 627             ty::adjustment::Adjust::NeverToAny =>
 628                 Some(ty::adjustment::Adjust::NeverToAny),
 629             ty::adjustment::Adjust::Pointer(ptr) =>
 630                 Some(ty::adjustment::Adjust::Pointer(ptr)),
 631             ty::adjustment::Adjust::Deref(ref overloaded) => {
 632                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 633             }
 634             ty::adjustment::Adjust::Borrow(ref autoref) => {
 635                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 636             }
 637         }
 638     }
 639 }
 640
 641 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 642     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 643     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 644         tcx.lift(&self.region).map(|region| {
 645             ty::adjustment::OverloadedDeref {
 646                 region,
 647                 mutbl: self.mutbl,
 648             }
 649         })
 650     }
 651 }
 652
 653 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 654     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 655     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 656         match *self {
 657             ty::adjustment::AutoBorrow::Ref(r, m) => {
 658                 tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 659             }
 660             ty::adjustment::AutoBorrow::RawPtr(m) => {
 661                 Some(ty::adjustment::AutoBorrow::RawPtr(m))
 662             }
 663         }
 664     }
 665 }
 666
 667 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 668     type Lifted = ty::GenSig<'tcx>;
 669     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 670         tcx.lift(&(self.yield_ty, self.return_ty))
 671            .map(|(yield_ty, return_ty)| {
 672                ty::GenSig {
 673                    yield_ty,
 674                    return_ty,
 675                }
 676            })
 677     }
 678 }
 679
 680 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 681     type Lifted = ty::FnSig<'tcx>;
 682     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 683         tcx.lift(&self.inputs_and_output).map(|x| {
 684             ty::FnSig {
 685                 inputs_and_output: x,
 686                 c_variadic: self.c_variadic,
 687                 unsafety: self.unsafety,
 688                 abi: self.abi,
 689             }
 690         })
 691     }
 692 }
 693
 694 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 695     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 696     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 697         tcx.lift(&self.expected).and_then(|expected| {
 698             tcx.lift(&self.found).map(|found| {
 699                 ty::error::ExpectedFound {
 700                     expected,
 701                     found,
 702                 }
 703             })
 704         })
 705     }
 706 }
 707
 708 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 709     type Lifted = ty::error::TypeError<'tcx>;
 710     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 711         use crate::ty::error::TypeError::*;
 712
 713         Some(match *self {
 714             Mismatch => Mismatch,
 715             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 716             AbiMismatch(x) => AbiMismatch(x),
 717             Mutability => Mutability,
 718             TupleSize(x) => TupleSize(x),
 719             ArgCount => ArgCount,
 720             RegionsDoesNotOutlive(a, b) => {
 721                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b))
 722             }
 723             RegionsInsufficientlyPolymorphic(a, b) => {
 724                 return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b))
 725             }
 726             RegionsOverlyPolymorphic(a, b) => {
 727                 return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b))
 728             }
 729             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 730             IntMismatch(x) => IntMismatch(x),
 731             FloatMismatch(x) => FloatMismatch(x),
 732             Traits(x) => Traits(x),
 733             VariadicMismatch(x) => VariadicMismatch(x),
 734             CyclicTy(t) => return tcx.lift(&t).map(|t| CyclicTy(t)),
 735             ProjectionMismatched(x) => ProjectionMismatched(x),
 736             ProjectionBoundsLength(x) => ProjectionBoundsLength(x),
 737             Sorts(ref x) => return tcx.lift(x).map(Sorts),
 738             ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch),
 739             ConstMismatch(ref x) => return tcx.lift(x).map(ConstMismatch),
 740         })
 741     }
 742 }
 743
 744 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 745     type Lifted = ty::InstanceDef<'tcx>;
 746     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 747         match *self {
 748             ty::InstanceDef::Item(def_id) =>
 749                 Some(ty::InstanceDef::Item(def_id)),
 750             ty::InstanceDef::VtableShim(def_id) =>
 751                 Some(ty::InstanceDef::VtableShim(def_id)),
 752             ty::InstanceDef::Intrinsic(def_id) =>
 753                 Some(ty::InstanceDef::Intrinsic(def_id)),
 754             ty::InstanceDef::FnPtrShim(def_id, ref ty) =>
 755                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?)),
 756             ty::InstanceDef::Virtual(def_id, n) =>
 757                 Some(ty::InstanceDef::Virtual(def_id, n)),
 758             ty::InstanceDef::ClosureOnceShim { call_once } =>
 759                 Some(ty::InstanceDef::ClosureOnceShim { call_once }),
 760             ty::InstanceDef::DropGlue(def_id, ref ty) =>
 761                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?)),
 762             ty::InstanceDef::CloneShim(def_id, ref ty) =>
 763                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?)),
 764         }
 765     }
 766 }
 767
 768 BraceStructLiftImpl! {
 769     impl<'a, 'tcx> Lift<'tcx> for ty::TypeAndMut<'a> {
 770         type Lifted = ty::TypeAndMut<'tcx>;
 771         ty, mutbl
 772     }
 773 }
 774
 775 BraceStructLiftImpl! {
 776     impl<'a, 'tcx> Lift<'tcx> for ty::Instance<'a> {
 777         type Lifted = ty::Instance<'tcx>;
 778         def, substs
 779     }
 780 }
 781
 782 BraceStructLiftImpl! {
 783     impl<'a, 'tcx> Lift<'tcx> for interpret::GlobalId<'a> {
 784         type Lifted = interpret::GlobalId<'tcx>;
 785         instance, promoted
 786     }
 787 }
 788
 789 ///////////////////////////////////////////////////////////////////////////
 790 // TypeFoldable implementations.
 791 //
 792 // Ideally, each type should invoke `folder.fold_foo(self)` and
 793 // nothing else. In some cases, though, we haven't gotten around to
 794 // adding methods on the `folder` yet, and thus the folding is
 795 // hard-coded here. This is less-flexible, because folders cannot
 796 // override the behavior, but there are a lot of random types and one
 797 // can easily refactor the folding into the TypeFolder trait as
 798 // needed.
 799
 800 /// AdtDefs are basically the same as a DefId.
 801 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 802     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _folder: &mut F) -> Self {
 803         *self
 804     }
 805
 806     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
 807         false
 808     }
 809 }
 810
 811 impl<'tcx, T:TypeFoldable<'tcx>, U:TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 812     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> (T, U) {
 813         (self.0.fold_with(folder), self.1.fold_with(folder))
 814     }
 815
 816     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 817         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 818     }
 819 }
 820
 821 EnumTypeFoldableImpl! {
 822     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 823         (Some)(a),
 824         (None),
 825     } where T: TypeFoldable<'tcx>
 826 }
 827
 828 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 829     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 830         Rc::new((**self).fold_with(folder))
 831     }
 832
 833     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 834         (**self).visit_with(visitor)
 835     }
 836 }
 837
 838 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 839     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 840         let content: T = (**self).fold_with(folder);
 841         box content
 842     }
 843
 844     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 845         (**self).visit_with(visitor)
 846     }
 847 }
 848
 849 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 850     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 851         self.iter().map(|t| t.fold_with(folder)).collect()
 852     }
 853
 854     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 855         self.iter().any(|t| t.visit_with(visitor))
 856     }
 857 }
 858
 859 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 860     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 861         self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>().into_boxed_slice()
 862     }
 863
 864     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 865         self.iter().any(|t| t.visit_with(visitor))
 866     }
 867 }
 868
 869 impl<'tcx, T:TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
 870     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 871         self.map_bound_ref(|ty| ty.fold_with(folder))
 872     }
 873
 874     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 875         folder.fold_binder(self)
 876     }
 877
 878     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 879         self.skip_binder().visit_with(visitor)
 880     }
 881
 882     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 883         visitor.visit_binder(self)
 884     }
 885 }
 886
 887 BraceStructTypeFoldableImpl! {
 888     impl<'tcx> TypeFoldable<'tcx> for ty::ParamEnv<'tcx> { reveal, caller_bounds, def_id }
 889 }
 890
 891 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> {
 892     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 893         let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
 894         folder.tcx().intern_existential_predicates(&v)
 895     }
 896
 897     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 898         self.iter().any(|p| p.visit_with(visitor))
 899     }
 900 }
 901
 902 EnumTypeFoldableImpl! {
 903     impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialPredicate<'tcx> {
 904         (ty::ExistentialPredicate::Trait)(a),
 905         (ty::ExistentialPredicate::Projection)(a),
 906         (ty::ExistentialPredicate::AutoTrait)(a),
 907     }
 908 }
 909
 910 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 911     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 912         let v = self.iter().map(|t| t.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
 913         folder.tcx().intern_type_list(&v)
 914     }
 915
 916     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 917         self.iter().any(|t| t.visit_with(visitor))
 918     }
 919 }
 920
 921 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 922     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 923         let v = self.iter().map(|t| t.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
 924         folder.tcx().intern_projs(&v)
 925     }
 926
 927     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 928         self.iter().any(|t| t.visit_with(visitor))
 929     }
 930 }
 931
 932 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 933     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 934         use crate::ty::InstanceDef::*;
 935         Self {
 936             substs: self.substs.fold_with(folder),
 937             def: match self.def {
 938                 Item(did) => Item(did.fold_with(folder)),
 939                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 940                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 941                 FnPtrShim(did, ty) => FnPtrShim(
 942                     did.fold_with(folder),
 943                     ty.fold_with(folder),
 944                 ),
 945                 Virtual(did, i) => Virtual(
 946                     did.fold_with(folder),
 947                     i,
 948                 ),
 949                 ClosureOnceShim { call_once } => ClosureOnceShim {
 950                     call_once: call_once.fold_with(folder),
 951                 },
 952                 DropGlue(did, ty) => DropGlue(
 953                     did.fold_with(folder),
 954                     ty.fold_with(folder),
 955                 ),
 956                 CloneShim(did, ty) => CloneShim(
 957                     did.fold_with(folder),
 958                     ty.fold_with(folder),
 959                 ),
 960             },
 961         }
 962     }
 963
 964     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 965         use crate::ty::InstanceDef::*;
 966         self.substs.visit_with(visitor) ||
 967         match self.def {
 968             Item(did) | VtableShim(did) | Intrinsic(did) | Virtual(did, _) => {
 969                 did.visit_with(visitor)
 970             },
 971             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 972                 did.visit_with(visitor) || ty.visit_with(visitor)
 973             },
 974             DropGlue(did, ty) => {
 975                 did.visit_with(visitor) || ty.visit_with(visitor)
 976             },
 977             ClosureOnceShim { call_once } => call_once.visit_with(visitor),
 978         }
 979     }
 980 }
 981
 982 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 983     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 984         Self {
 985             instance: self.instance.fold_with(folder),
 986             promoted: self.promoted
 987         }
 988     }
 989
 990     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 991         self.instance.visit_with(visitor)
 992     }
 993 }
 994
 995 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 996     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 997         let sty = match self.sty {
 998             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 999             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
1000             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
1001             ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)),
1002             ty::Dynamic(ref trait_ty, ref region) =>
1003                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder)),
1004             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
1005             ty::FnDef(def_id, substs) => {
1006                 ty::FnDef(def_id, substs.fold_with(folder))
1007             }
1008             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
1009             ty::Ref(ref r, ty, mutbl) => {
1010                 ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl)
1011             }
1012             ty::Generator(did, substs, movability) => {
1013                 ty::Generator(
1014                     did,
1015                     substs.fold_with(folder),
1016                     movability)
1017             }
1018             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
1019             ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)),
1020             ty::Projection(ref data) => ty::Projection(data.fold_with(folder)),
1021             ty::UnnormalizedProjection(ref data) => {
1022                 ty::UnnormalizedProjection(data.fold_with(folder))
1023             }
1024             ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)),
1025
1026             ty::Bool |
1027             ty::Char |
1028             ty::Str |
1029             ty::Int(_) |
1030             ty::Uint(_) |
1031             ty::Float(_) |
1032             ty::Error |
1033             ty::Infer(_) |
1034             ty::Param(..) |
1035             ty::Bound(..) |
1036             ty::Placeholder(..) |
1037             ty::Never |
1038             ty::Foreign(..) => return self
1039         };
1040
1041         if self.sty == sty {
1042             self
1043         } else {
1044             folder.tcx().mk_ty(sty)
1045         }
1046     }
1047
1048     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1049         folder.fold_ty(*self)
1050     }
1051
1052     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1053         match self.sty {
1054             ty::RawPtr(ref tm) => tm.visit_with(visitor),
1055             ty::Array(typ, sz) => typ.visit_with(visitor) || sz.visit_with(visitor),
1056             ty::Slice(typ) => typ.visit_with(visitor),
1057             ty::Adt(_, substs) => substs.visit_with(visitor),
1058             ty::Dynamic(ref trait_ty, ref reg) =>
1059                 trait_ty.visit_with(visitor) || reg.visit_with(visitor),
1060             ty::Tuple(ts) => ts.visit_with(visitor),
1061             ty::FnDef(_, substs) => substs.visit_with(visitor),
1062             ty::FnPtr(ref f) => f.visit_with(visitor),
1063             ty::Ref(r, ty, _) => r.visit_with(visitor) || ty.visit_with(visitor),
1064             ty::Generator(_did, ref substs, _) => {
1065                 substs.visit_with(visitor)
1066             }
1067             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
1068             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
1069             ty::Projection(ref data) | ty::UnnormalizedProjection(ref data) => {
1070                 data.visit_with(visitor)
1071             }
1072             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
1073
1074             ty::Bool |
1075             ty::Char |
1076             ty::Str |
1077             ty::Int(_) |
1078             ty::Uint(_) |
1079             ty::Float(_) |
1080             ty::Error |
1081             ty::Infer(_) |
1082             ty::Bound(..) |
1083             ty::Placeholder(..) |
1084             ty::Param(..) |
1085             ty::Never |
1086             ty::Foreign(..) => false,
1087         }
1088     }
1089
1090     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1091         visitor.visit_ty(self)
1092     }
1093 }
1094
1095 BraceStructTypeFoldableImpl! {
1096     impl<'tcx> TypeFoldable<'tcx> for ty::TypeAndMut<'tcx> {
1097         ty, mutbl
1098     }
1099 }
1100
1101 BraceStructTypeFoldableImpl! {
1102     impl<'tcx> TypeFoldable<'tcx> for ty::GenSig<'tcx> {
1103         yield_ty, return_ty
1104     }
1105 }
1106
1107 BraceStructTypeFoldableImpl! {
1108     impl<'tcx> TypeFoldable<'tcx> for ty::FnSig<'tcx> {
1109         inputs_and_output, c_variadic, unsafety, abi
1110     }
1111 }
1112
1113 BraceStructTypeFoldableImpl! {
1114     impl<'tcx> TypeFoldable<'tcx> for ty::TraitRef<'tcx> { def_id, substs }
1115 }
1116
1117 BraceStructTypeFoldableImpl! {
1118     impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialTraitRef<'tcx> { def_id, substs }
1119 }
1120
1121 BraceStructTypeFoldableImpl! {
1122     impl<'tcx> TypeFoldable<'tcx> for ty::ImplHeader<'tcx> {
1123         impl_def_id,
1124         self_ty,
1125         trait_ref,
1126         predicates,
1127     }
1128 }
1129
1130 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1131     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _folder: &mut F) -> Self {
1132         *self
1133     }
1134
1135     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1136         folder.fold_region(*self)
1137     }
1138
1139     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1140         false
1141     }
1142
1143     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1144         visitor.visit_region(*self)
1145     }
1146 }
1147
1148 BraceStructTypeFoldableImpl! {
1149     impl<'tcx> TypeFoldable<'tcx> for ty::ClosureSubsts<'tcx> {
1150         substs,
1151     }
1152 }
1153
1154 BraceStructTypeFoldableImpl! {
1155     impl<'tcx> TypeFoldable<'tcx> for ty::GeneratorSubsts<'tcx> {
1156         substs,
1157     }
1158 }
1159
1160 BraceStructTypeFoldableImpl! {
1161     impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::Adjustment<'tcx> {
1162         kind,
1163         target,
1164     }
1165 }
1166
1167 EnumTypeFoldableImpl! {
1168     impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::Adjust<'tcx> {
1169         (ty::adjustment::Adjust::NeverToAny),
1170         (ty::adjustment::Adjust::Pointer)(a),
1171         (ty::adjustment::Adjust::Deref)(a),
1172         (ty::adjustment::Adjust::Borrow)(a),
1173     }
1174 }
1175
1176 BraceStructTypeFoldableImpl! {
1177     impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::OverloadedDeref<'tcx> {
1178         region, mutbl,
1179     }
1180 }
1181
1182 EnumTypeFoldableImpl! {
1183     impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::AutoBorrow<'tcx> {
1184         (ty::adjustment::AutoBorrow::Ref)(a, b),
1185         (ty::adjustment::AutoBorrow::RawPtr)(m),
1186     }
1187 }
1188
1189 BraceStructTypeFoldableImpl! {
1190     impl<'tcx> TypeFoldable<'tcx> for ty::GenericPredicates<'tcx> {
1191         parent, predicates
1192     }
1193 }
1194
1195 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1196     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1197         let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
1198         folder.tcx().intern_predicates(&v)
1199     }
1200
1201     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1202         self.iter().any(|p| p.visit_with(visitor))
1203     }
1204 }
1205
1206 EnumTypeFoldableImpl! {
1207     impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1208         (ty::Predicate::Trait)(a),
1209         (ty::Predicate::Subtype)(a),
1210         (ty::Predicate::RegionOutlives)(a),
1211         (ty::Predicate::TypeOutlives)(a),
1212         (ty::Predicate::Projection)(a),
1213         (ty::Predicate::WellFormed)(a),
1214         (ty::Predicate::ClosureKind)(a, b, c),
1215         (ty::Predicate::ObjectSafe)(a),
1216         (ty::Predicate::ConstEvaluatable)(a, b),
1217     }
1218 }
1219
1220 BraceStructTypeFoldableImpl! {
1221     impl<'tcx> TypeFoldable<'tcx> for ty::ProjectionPredicate<'tcx> {
1222         projection_ty, ty
1223     }
1224 }
1225
1226 BraceStructTypeFoldableImpl! {
1227     impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialProjection<'tcx> {
1228         ty, substs, item_def_id
1229     }
1230 }
1231
1232 BraceStructTypeFoldableImpl! {
1233     impl<'tcx> TypeFoldable<'tcx> for ty::ProjectionTy<'tcx> {
1234         substs, item_def_id
1235     }
1236 }
1237
1238 BraceStructTypeFoldableImpl! {
1239     impl<'tcx> TypeFoldable<'tcx> for ty::InstantiatedPredicates<'tcx> {
1240         predicates
1241     }
1242 }
1243
1244 BraceStructTypeFoldableImpl! {
1245     impl<'tcx, T> TypeFoldable<'tcx> for ty::ParamEnvAnd<'tcx, T> {
1246         param_env, value
1247     } where T: TypeFoldable<'tcx>
1248 }
1249
1250 BraceStructTypeFoldableImpl! {
1251     impl<'tcx> TypeFoldable<'tcx> for ty::SubtypePredicate<'tcx> {
1252         a_is_expected, a, b
1253     }
1254 }
1255
1256 BraceStructTypeFoldableImpl! {
1257     impl<'tcx> TypeFoldable<'tcx> for ty::TraitPredicate<'tcx> {
1258         trait_ref
1259     }
1260 }
1261
1262 TupleStructTypeFoldableImpl! {
1263     impl<'tcx,T,U> TypeFoldable<'tcx> for ty::OutlivesPredicate<T,U> {
1264         a, b
1265     } where T : TypeFoldable<'tcx>, U : TypeFoldable<'tcx>,
1266 }
1267
1268 BraceStructTypeFoldableImpl! {
1269     impl<'tcx> TypeFoldable<'tcx> for ty::ClosureUpvar<'tcx> {
1270         res, span, ty
1271     }
1272 }
1273
1274 BraceStructTypeFoldableImpl! {
1275     impl<'tcx, T> TypeFoldable<'tcx> for ty::error::ExpectedFound<T> {
1276         expected, found
1277     } where T: TypeFoldable<'tcx>
1278 }
1279
1280 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1281     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1282         self.iter().map(|x| x.fold_with(folder)).collect()
1283     }
1284
1285     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1286         self.iter().any(|t| t.visit_with(visitor))
1287     }
1288 }
1289
1290 EnumTypeFoldableImpl! {
1291     impl<'tcx> TypeFoldable<'tcx> for ty::error::TypeError<'tcx> {
1292         (ty::error::TypeError::Mismatch),
1293         (ty::error::TypeError::UnsafetyMismatch)(x),
1294         (ty::error::TypeError::AbiMismatch)(x),
1295         (ty::error::TypeError::Mutability),
1296         (ty::error::TypeError::TupleSize)(x),
1297         (ty::error::TypeError::ArgCount),
1298         (ty::error::TypeError::RegionsDoesNotOutlive)(a, b),
1299         (ty::error::TypeError::RegionsInsufficientlyPolymorphic)(a, b),
1300         (ty::error::TypeError::RegionsOverlyPolymorphic)(a, b),
1301         (ty::error::TypeError::RegionsPlaceholderMismatch),
1302         (ty::error::TypeError::IntMismatch)(x),
1303         (ty::error::TypeError::FloatMismatch)(x),
1304         (ty::error::TypeError::Traits)(x),
1305         (ty::error::TypeError::VariadicMismatch)(x),
1306         (ty::error::TypeError::CyclicTy)(t),
1307         (ty::error::TypeError::ProjectionMismatched)(x),
1308         (ty::error::TypeError::ProjectionBoundsLength)(x),
1309         (ty::error::TypeError::Sorts)(x),
1310         (ty::error::TypeError::ExistentialMismatch)(x),
1311         (ty::error::TypeError::ConstMismatch)(x),
1312     }
1313 }
1314
1315 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1316     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1317         let ty = self.ty.fold_with(folder);
1318         let val = self.val.fold_with(folder);
1319         folder.tcx().mk_const(ty::Const {
1320             ty,
1321             val
1322         })
1323     }
1324
1325     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1326         folder.fold_const(*self)
1327     }
1328
1329     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1330         self.ty.visit_with(visitor) || self.val.visit_with(visitor)
1331     }
1332
1333     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1334         visitor.visit_const(self)
1335     }
1336 }
1337
1338 impl<'tcx> TypeFoldable<'tcx> for ConstValue<'tcx> {
1339     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
1340         match *self {
1341             ConstValue::ByRef(ptr, alloc) => ConstValue::ByRef(ptr, alloc),
1342             ConstValue::Infer(ic) => ConstValue::Infer(ic.fold_with(folder)),
1343             ConstValue::Param(p) => ConstValue::Param(p.fold_with(folder)),
1344             ConstValue::Placeholder(p) => ConstValue::Placeholder(p),
1345             ConstValue::Scalar(a) => ConstValue::Scalar(a),
1346             ConstValue::Slice { data, start, end } => ConstValue::Slice { data, start, end },
1347             ConstValue::Unevaluated(did, substs)
1348                 => ConstValue::Unevaluated(did, substs.fold_with(folder)),
1349         }
1350     }
1351
1352     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1353         match *self {
1354             ConstValue::ByRef(..) => false,
1355             ConstValue::Infer(ic) => ic.visit_with(visitor),
1356             ConstValue::Param(p) => p.visit_with(visitor),
1357             ConstValue::Placeholder(_) => false,
1358             ConstValue::Scalar(_) => false,
1359             ConstValue::Slice { .. } => false,
1360             ConstValue::Unevaluated(_, substs) => substs.visit_with(visitor),
1361         }
1362     }
1363 }
1364
1365 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1366     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _folder: &mut F) -> Self {
1367         *self
1368     }
1369
1370     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1371         false
1372     }
1373 }