compiler/rustc_middle/src/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 and proc-macros to help with the tedium.
   4
   5 use crate::mir::interpret;
   6 use crate::mir::ProjectionKind;
   7 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
   8 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
   9 use crate::ty::{self, InferConst, Lift, Ty, TyCtxt};
  10 use rustc_data_structures::functor::IdFunctor;
  11 use rustc_hir as hir;
  12 use rustc_hir::def::Namespace;
  13 use rustc_hir::def_id::CRATE_DEF_INDEX;
  14 use rustc_index::vec::{Idx, IndexVec};
  15
  16 use std::fmt;
  17 use std::ops::ControlFlow;
  18 use std::rc::Rc;
  19 use std::sync::Arc;
  20
  21 impl fmt::Debug for ty::TraitDef {
  22     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  23         ty::tls::with(|tcx| {
  24             with_no_trimmed_paths(|| {
  25                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.def_id, &[])
  26             })?;
  27             Ok(())
  28         })
  29     }
  30 }
  31
  32 impl fmt::Debug for ty::AdtDef {
  33     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  34         ty::tls::with(|tcx| {
  35             with_no_trimmed_paths(|| {
  36                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.did, &[])
  37             })?;
  38             Ok(())
  39         })
  40     }
  41 }
  42
  43 impl fmt::Debug for ty::UpvarId {
  44     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  45         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  46         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  47     }
  48 }
  49
  50 impl fmt::Debug for ty::UpvarBorrow<'tcx> {
  51     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  52         write!(f, "UpvarBorrow({:?}, {:?})", self.kind, self.region)
  53     }
  54 }
  55
  56 impl fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  57     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  58         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
  59     }
  60 }
  61
  62 impl fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  63     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  64         write!(f, "{:?} -> {}", self.kind, self.target)
  65     }
  66 }
  67
  68 impl fmt::Debug for ty::BoundRegionKind {
  69     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  70         match *self {
  71             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  72             ty::BrNamed(did, name) => {
  73                 if did.index == CRATE_DEF_INDEX {
  74                     write!(f, "BrNamed({})", name)
  75                 } else {
  76                     write!(f, "BrNamed({:?}, {})", did, name)
  77                 }
  78             }
  79             ty::BrEnv => write!(f, "BrEnv"),
  80         }
  81     }
  82 }
  83
  84 impl fmt::Debug for ty::RegionKind {
  85     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  86         match *self {
  87             ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name),
  88
  89             ty::ReLateBound(binder_id, ref bound_region) => {
  90                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
  91             }
  92
  93             ty::ReFree(ref fr) => fr.fmt(f),
  94
  95             ty::ReStatic => write!(f, "ReStatic"),
  96
  97             ty::ReVar(ref vid) => vid.fmt(f),
  98
  99             ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder),
 100
 101             ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui),
 102
 103             ty::ReErased => write!(f, "ReErased"),
 104         }
 105     }
 106 }
 107
 108 impl fmt::Debug for ty::FreeRegion {
 109     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 110         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 111     }
 112 }
 113
 114 impl fmt::Debug for ty::FnSig<'tcx> {
 115     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 116         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 117     }
 118 }
 119
 120 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 121     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 122         write!(f, "_#{}c", self.index)
 123     }
 124 }
 125
 126 impl fmt::Debug for ty::RegionVid {
 127     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 128         write!(f, "'_#{}r", self.index())
 129     }
 130 }
 131
 132 impl fmt::Debug for ty::TraitRef<'tcx> {
 133     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 134         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 135     }
 136 }
 137
 138 impl fmt::Debug for Ty<'tcx> {
 139     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 140         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 141     }
 142 }
 143
 144 impl fmt::Debug for ty::ParamTy {
 145     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 146         write!(f, "{}/#{}", self.name, self.index)
 147     }
 148 }
 149
 150 impl fmt::Debug for ty::ParamConst {
 151     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 152         write!(f, "{}/#{}", self.name, self.index)
 153     }
 154 }
 155
 156 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 157     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 158         write!(f, "TraitPredicate({:?})", self.trait_ref)
 159     }
 160 }
 161
 162 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 163     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 164         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 165     }
 166 }
 167
 168 impl fmt::Debug for ty::Predicate<'tcx> {
 169     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 170         write!(f, "{:?}", self.kind())
 171     }
 172 }
 173
 174 impl fmt::Debug for ty::PredicateKind<'tcx> {
 175     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 176         match *self {
 177             ty::PredicateKind::Trait(ref a, constness) => {
 178                 if let hir::Constness::Const = constness {
 179                     write!(f, "const ")?;
 180                 }
 181                 a.fmt(f)
 182             }
 183             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 184             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 185             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 186             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 187             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 188             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 189                 write!(f, "ObjectSafe({:?})", trait_def_id)
 190             }
 191             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 192                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 193             }
 194             ty::PredicateKind::ConstEvaluatable(def_id, substs) => {
 195                 write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
 196             }
 197             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 198             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 199                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 200             }
 201         }
 202     }
 203 }
 204
 205 ///////////////////////////////////////////////////////////////////////////
 206 // Atomic structs
 207 //
 208 // For things that don't carry any arena-allocated data (and are
 209 // copy...), just add them to this list.
 210
 211 TrivialTypeFoldableAndLiftImpls! {
 212     (),
 213     bool,
 214     usize,
 215     ::rustc_target::abi::VariantIdx,
 216     u32,
 217     u64,
 218     String,
 219     crate::middle::region::Scope,
 220     crate::ty::FloatTy,
 221     ::rustc_ast::InlineAsmOptions,
 222     ::rustc_ast::InlineAsmTemplatePiece,
 223     ::rustc_ast::NodeId,
 224     ::rustc_span::symbol::Symbol,
 225     ::rustc_hir::def::Res,
 226     ::rustc_hir::def_id::DefId,
 227     ::rustc_hir::def_id::LocalDefId,
 228     ::rustc_hir::HirId,
 229     ::rustc_hir::LlvmInlineAsmInner,
 230     ::rustc_hir::MatchSource,
 231     ::rustc_hir::Mutability,
 232     ::rustc_hir::Unsafety,
 233     ::rustc_target::asm::InlineAsmRegOrRegClass,
 234     ::rustc_target::spec::abi::Abi,
 235     crate::mir::coverage::ExpressionOperandId,
 236     crate::mir::coverage::CounterValueReference,
 237     crate::mir::coverage::InjectedExpressionId,
 238     crate::mir::coverage::InjectedExpressionIndex,
 239     crate::mir::coverage::MappedExpressionIndex,
 240     crate::mir::Local,
 241     crate::mir::Promoted,
 242     crate::traits::Reveal,
 243     crate::ty::adjustment::AutoBorrowMutability,
 244     crate::ty::AdtKind,
 245     // Including `BoundRegionKind` is a *bit* dubious, but direct
 246     // references to bound region appear in `ty::Error`, and aren't
 247     // really meant to be folded. In general, we can only fold a fully
 248     // general `Region`.
 249     crate::ty::BoundRegionKind,
 250     crate::ty::AssocItem,
 251     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 252     crate::ty::ClosureKind,
 253     crate::ty::FreeRegion,
 254     crate::ty::InferTy,
 255     crate::ty::IntVarValue,
 256     crate::ty::ParamConst,
 257     crate::ty::ParamTy,
 258     crate::ty::adjustment::PointerCast,
 259     crate::ty::RegionVid,
 260     crate::ty::UniverseIndex,
 261     crate::ty::Variance,
 262     ::rustc_span::Span,
 263 }
 264
 265 ///////////////////////////////////////////////////////////////////////////
 266 // Lift implementations
 267
 268 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 269 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 270     type Lifted = (A::Lifted, B::Lifted);
 271     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 272         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 273     }
 274 }
 275
 276 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 277     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 278     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 279         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 280     }
 281 }
 282
 283 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 284     type Lifted = Option<T::Lifted>;
 285     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 286         match self {
 287             Some(x) => tcx.lift(x).map(Some),
 288             None => Some(None),
 289         }
 290     }
 291 }
 292
 293 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 294     type Lifted = Result<T::Lifted, E::Lifted>;
 295     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 296         match self {
 297             Ok(x) => tcx.lift(x).map(Ok),
 298             Err(e) => tcx.lift(e).map(Err),
 299         }
 300     }
 301 }
 302
 303 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 304     type Lifted = Box<T::Lifted>;
 305     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 306         tcx.lift(*self).map(Box::new)
 307     }
 308 }
 309
 310 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 311     type Lifted = Rc<T::Lifted>;
 312     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 313         tcx.lift(self.as_ref().clone()).map(Rc::new)
 314     }
 315 }
 316
 317 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 318     type Lifted = Arc<T::Lifted>;
 319     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 320         tcx.lift(self.as_ref().clone()).map(Arc::new)
 321     }
 322 }
 323 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 324     type Lifted = Vec<T::Lifted>;
 325     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 326         self.into_iter().map(|v| tcx.lift(v)).collect()
 327     }
 328 }
 329
 330 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 331     type Lifted = IndexVec<I, T::Lifted>;
 332     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 333         self.into_iter().map(|e| tcx.lift(e)).collect()
 334     }
 335 }
 336
 337 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 338     type Lifted = ty::TraitRef<'tcx>;
 339     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 340         tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 341     }
 342 }
 343
 344 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 345     type Lifted = ty::ExistentialTraitRef<'tcx>;
 346     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 347         tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 348     }
 349 }
 350
 351 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 352     type Lifted = ty::ExistentialPredicate<'tcx>;
 353     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 354         match self {
 355             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 356             ty::ExistentialPredicate::Projection(x) => {
 357                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 358             }
 359             ty::ExistentialPredicate::AutoTrait(def_id) => {
 360                 Some(ty::ExistentialPredicate::AutoTrait(def_id))
 361             }
 362         }
 363     }
 364 }
 365
 366 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 367     type Lifted = ty::TraitPredicate<'tcx>;
 368     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 369         tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref })
 370     }
 371 }
 372
 373 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 374     type Lifted = ty::SubtypePredicate<'tcx>;
 375     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 376         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 377             a_is_expected: self.a_is_expected,
 378             a,
 379             b,
 380         })
 381     }
 382 }
 383
 384 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 385     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 386     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 387         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 388     }
 389 }
 390
 391 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 392     type Lifted = ty::ProjectionTy<'tcx>;
 393     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 394         tcx.lift(self.substs)
 395             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 396     }
 397 }
 398
 399 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 400     type Lifted = ty::ProjectionPredicate<'tcx>;
 401     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 402         tcx.lift((self.projection_ty, self.ty))
 403             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 404     }
 405 }
 406
 407 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 408     type Lifted = ty::ExistentialProjection<'tcx>;
 409     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 410         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 411             substs,
 412             ty: tcx.lift(self.ty).expect("type must lift when substs do"),
 413             item_def_id: self.item_def_id,
 414         })
 415     }
 416 }
 417
 418 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 419     type Lifted = ty::PredicateKind<'tcx>;
 420     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 421         match self {
 422             ty::PredicateKind::Trait(data, constness) => {
 423                 tcx.lift(data).map(|data| ty::PredicateKind::Trait(data, constness))
 424             }
 425             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 426             ty::PredicateKind::RegionOutlives(data) => {
 427                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 428             }
 429             ty::PredicateKind::TypeOutlives(data) => {
 430                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 431             }
 432             ty::PredicateKind::Projection(data) => {
 433                 tcx.lift(data).map(ty::PredicateKind::Projection)
 434             }
 435             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 436             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 437                 tcx.lift(closure_substs).map(|closure_substs| {
 438                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 439                 })
 440             }
 441             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 442                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 443             }
 444             ty::PredicateKind::ConstEvaluatable(def_id, substs) => {
 445                 tcx.lift(substs).map(|substs| ty::PredicateKind::ConstEvaluatable(def_id, substs))
 446             }
 447             ty::PredicateKind::ConstEquate(c1, c2) => {
 448                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 449             }
 450             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 451                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 452             }
 453         }
 454     }
 455 }
 456
 457 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 458 where
 459     <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>,
 460 {
 461     type Lifted = ty::Binder<'tcx, T::Lifted>;
 462     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 463         let bound_vars = tcx.lift(self.bound_vars());
 464         tcx.lift(self.skip_binder())
 465             .zip(bound_vars)
 466             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 467     }
 468 }
 469
 470 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 471     type Lifted = ty::ParamEnv<'tcx>;
 472     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 473         tcx.lift(self.caller_bounds())
 474             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
 475     }
 476 }
 477
 478 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 479     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 480     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 481         tcx.lift(self.param_env).and_then(|param_env| {
 482             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 483         })
 484     }
 485 }
 486
 487 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 488     type Lifted = ty::ClosureSubsts<'tcx>;
 489     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 490         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 491     }
 492 }
 493
 494 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 495     type Lifted = ty::GeneratorSubsts<'tcx>;
 496     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 497         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 498     }
 499 }
 500
 501 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 502     type Lifted = ty::adjustment::Adjustment<'tcx>;
 503     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 504         let ty::adjustment::Adjustment { kind, target } = self;
 505         tcx.lift(kind).and_then(|kind| {
 506             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 507         })
 508     }
 509 }
 510
 511 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 512     type Lifted = ty::adjustment::Adjust<'tcx>;
 513     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 514         match self {
 515             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 516             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 517             ty::adjustment::Adjust::Deref(overloaded) => {
 518                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 519             }
 520             ty::adjustment::Adjust::Borrow(autoref) => {
 521                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 522             }
 523         }
 524     }
 525 }
 526
 527 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 528     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 529     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 530         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 531             region,
 532             mutbl: self.mutbl,
 533             span: self.span,
 534         })
 535     }
 536 }
 537
 538 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 539     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 540     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 541         match self {
 542             ty::adjustment::AutoBorrow::Ref(r, m) => {
 543                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 544             }
 545             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 546         }
 547     }
 548 }
 549
 550 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 551     type Lifted = ty::GenSig<'tcx>;
 552     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 553         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 554             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 555     }
 556 }
 557
 558 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 559     type Lifted = ty::FnSig<'tcx>;
 560     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 561         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 562             inputs_and_output: x,
 563             c_variadic: self.c_variadic,
 564             unsafety: self.unsafety,
 565             abi: self.abi,
 566         })
 567     }
 568 }
 569
 570 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 571     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 572     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 573         let ty::error::ExpectedFound { expected, found } = self;
 574         tcx.lift(expected).and_then(|expected| {
 575             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 576         })
 577     }
 578 }
 579
 580 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 581     type Lifted = ty::error::TypeError<'tcx>;
 582     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 583         use crate::ty::error::TypeError::*;
 584
 585         Some(match self {
 586             Mismatch => Mismatch,
 587             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 588             AbiMismatch(x) => AbiMismatch(x),
 589             Mutability => Mutability,
 590             ArgumentMutability(i) => ArgumentMutability(i),
 591             TupleSize(x) => TupleSize(x),
 592             FixedArraySize(x) => FixedArraySize(x),
 593             ArgCount => ArgCount,
 594             RegionsDoesNotOutlive(a, b) => {
 595                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 596             }
 597             RegionsInsufficientlyPolymorphic(a, b) => {
 598                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 599             }
 600             RegionsOverlyPolymorphic(a, b) => {
 601                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 602             }
 603             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 604             IntMismatch(x) => IntMismatch(x),
 605             FloatMismatch(x) => FloatMismatch(x),
 606             Traits(x) => Traits(x),
 607             VariadicMismatch(x) => VariadicMismatch(x),
 608             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 609             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 610             ProjectionMismatched(x) => ProjectionMismatched(x),
 611             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 612             Sorts(x) => return tcx.lift(x).map(Sorts),
 613             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 614             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 615             IntrinsicCast => IntrinsicCast,
 616             TargetFeatureCast(x) => TargetFeatureCast(x),
 617             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 618         })
 619     }
 620 }
 621
 622 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 623     type Lifted = ty::InstanceDef<'tcx>;
 624     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 625         match self {
 626             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 627             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 628             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 629             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 630             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 631                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 632             }
 633             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 634             ty::InstanceDef::ClosureOnceShim { call_once } => {
 635                 Some(ty::InstanceDef::ClosureOnceShim { call_once })
 636             }
 637             ty::InstanceDef::DropGlue(def_id, ty) => {
 638                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 639             }
 640             ty::InstanceDef::CloneShim(def_id, ty) => {
 641                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 642             }
 643         }
 644     }
 645 }
 646
 647 ///////////////////////////////////////////////////////////////////////////
 648 // TypeFoldable implementations.
 649 //
 650 // Ideally, each type should invoke `folder.fold_foo(self)` and
 651 // nothing else. In some cases, though, we haven't gotten around to
 652 // adding methods on the `folder` yet, and thus the folding is
 653 // hard-coded here. This is less-flexible, because folders cannot
 654 // override the behavior, but there are a lot of random types and one
 655 // can easily refactor the folding into the TypeFolder trait as
 656 // needed.
 657
 658 /// AdtDefs are basically the same as a DefId.
 659 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 660     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 661         self
 662     }
 663
 664     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 665         ControlFlow::CONTINUE
 666     }
 667 }
 668
 669 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 670     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (T, U) {
 671         (self.0.fold_with(folder), self.1.fold_with(folder))
 672     }
 673
 674     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 675         self.0.visit_with(visitor)?;
 676         self.1.visit_with(visitor)
 677     }
 678 }
 679
 680 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 681     for (A, B, C)
 682 {
 683     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (A, B, C) {
 684         (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
 685     }
 686
 687     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 688         self.0.visit_with(visitor)?;
 689         self.1.visit_with(visitor)?;
 690         self.2.visit_with(visitor)
 691     }
 692 }
 693
 694 EnumTypeFoldableImpl! {
 695     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 696         (Some)(a),
 697         (None),
 698     } where T: TypeFoldable<'tcx>
 699 }
 700
 701 EnumTypeFoldableImpl! {
 702     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 703         (Ok)(a),
 704         (Err)(a),
 705     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 706 }
 707
 708 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 709     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 710         // FIXME: Reuse the `Rc` here.
 711         Rc::new((*self).clone().fold_with(folder))
 712     }
 713
 714     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 715         (**self).visit_with(visitor)
 716     }
 717 }
 718
 719 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 720     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 721         // FIXME: Reuse the `Arc` here.
 722         Arc::new((*self).clone().fold_with(folder))
 723     }
 724
 725     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 726         (**self).visit_with(visitor)
 727     }
 728 }
 729
 730 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 731     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 732         self.map_id(|value| value.fold_with(folder))
 733     }
 734
 735     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 736         (**self).visit_with(visitor)
 737     }
 738 }
 739
 740 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 741     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 742         self.map_id(|t| t.fold_with(folder))
 743     }
 744
 745     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 746         self.iter().try_for_each(|t| t.visit_with(visitor))
 747     }
 748 }
 749
 750 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 751     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 752         self.map_id(|t| t.fold_with(folder))
 753     }
 754
 755     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 756         self.iter().try_for_each(|t| t.visit_with(visitor))
 757     }
 758 }
 759
 760 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 761     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 762         self.map_bound(|ty| ty.fold_with(folder))
 763     }
 764
 765     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 766         folder.fold_binder(self)
 767     }
 768
 769     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 770         self.as_ref().skip_binder().visit_with(visitor)
 771     }
 772
 773     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 774         visitor.visit_binder(self)
 775     }
 776 }
 777
 778 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 779     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 780         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 781     }
 782
 783     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 784         self.iter().try_for_each(|p| p.visit_with(visitor))
 785     }
 786 }
 787
 788 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 789     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 790         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_type_list(v))
 791     }
 792
 793     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 794         self.iter().try_for_each(|t| t.visit_with(visitor))
 795     }
 796 }
 797
 798 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 799     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 800         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 801     }
 802
 803     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 804         self.iter().try_for_each(|t| t.visit_with(visitor))
 805     }
 806 }
 807
 808 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 809     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 810         use crate::ty::InstanceDef::*;
 811         Self {
 812             substs: self.substs.fold_with(folder),
 813             def: match self.def {
 814                 Item(def) => Item(def.fold_with(folder)),
 815                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 816                 ReifyShim(did) => ReifyShim(did.fold_with(folder)),
 817                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 818                 FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)),
 819                 Virtual(did, i) => Virtual(did.fold_with(folder), i),
 820                 ClosureOnceShim { call_once } => {
 821                     ClosureOnceShim { call_once: call_once.fold_with(folder) }
 822                 }
 823                 DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)),
 824                 CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)),
 825             },
 826         }
 827     }
 828
 829     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 830         use crate::ty::InstanceDef::*;
 831         self.substs.visit_with(visitor)?;
 832         match self.def {
 833             Item(def) => def.visit_with(visitor),
 834             VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 835                 did.visit_with(visitor)
 836             }
 837             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 838                 did.visit_with(visitor)?;
 839                 ty.visit_with(visitor)
 840             }
 841             DropGlue(did, ty) => {
 842                 did.visit_with(visitor)?;
 843                 ty.visit_with(visitor)
 844             }
 845             ClosureOnceShim { call_once } => call_once.visit_with(visitor),
 846         }
 847     }
 848 }
 849
 850 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 851     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 852         Self { instance: self.instance.fold_with(folder), promoted: self.promoted }
 853     }
 854
 855     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 856         self.instance.visit_with(visitor)
 857     }
 858 }
 859
 860 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 861     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 862         let kind = match *self.kind() {
 863             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 864             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
 865             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
 866             ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)),
 867             ty::Dynamic(trait_ty, region) => {
 868                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder))
 869             }
 870             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
 871             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.fold_with(folder)),
 872             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
 873             ty::Ref(r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl),
 874             ty::Generator(did, substs, movability) => {
 875                 ty::Generator(did, substs.fold_with(folder), movability)
 876             }
 877             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
 878             ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)),
 879             ty::Projection(data) => ty::Projection(data.fold_with(folder)),
 880             ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)),
 881
 882             ty::Bool
 883             | ty::Char
 884             | ty::Str
 885             | ty::Int(_)
 886             | ty::Uint(_)
 887             | ty::Float(_)
 888             | ty::Error(_)
 889             | ty::Infer(_)
 890             | ty::Param(..)
 891             | ty::Bound(..)
 892             | ty::Placeholder(..)
 893             | ty::Never
 894             | ty::Foreign(..) => return self,
 895         };
 896
 897         if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) }
 898     }
 899
 900     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 901         folder.fold_ty(self)
 902     }
 903
 904     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 905         match self.kind() {
 906             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 907             ty::Array(typ, sz) => {
 908                 typ.visit_with(visitor)?;
 909                 sz.visit_with(visitor)
 910             }
 911             ty::Slice(typ) => typ.visit_with(visitor),
 912             ty::Adt(_, substs) => substs.visit_with(visitor),
 913             ty::Dynamic(ref trait_ty, ref reg) => {
 914                 trait_ty.visit_with(visitor)?;
 915                 reg.visit_with(visitor)
 916             }
 917             ty::Tuple(ts) => ts.visit_with(visitor),
 918             ty::FnDef(_, substs) => substs.visit_with(visitor),
 919             ty::FnPtr(ref f) => f.visit_with(visitor),
 920             ty::Ref(r, ty, _) => {
 921                 r.visit_with(visitor)?;
 922                 ty.visit_with(visitor)
 923             }
 924             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 925             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 926             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 927             ty::Projection(ref data) => data.visit_with(visitor),
 928             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 929
 930             ty::Bool
 931             | ty::Char
 932             | ty::Str
 933             | ty::Int(_)
 934             | ty::Uint(_)
 935             | ty::Float(_)
 936             | ty::Error(_)
 937             | ty::Infer(_)
 938             | ty::Bound(..)
 939             | ty::Placeholder(..)
 940             | ty::Param(..)
 941             | ty::Never
 942             | ty::Foreign(..) => ControlFlow::CONTINUE,
 943         }
 944     }
 945
 946     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 947         visitor.visit_ty(self)
 948     }
 949 }
 950
 951 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
 952     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 953         self
 954     }
 955
 956     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 957         folder.fold_region(self)
 958     }
 959
 960     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 961         ControlFlow::CONTINUE
 962     }
 963
 964     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 965         visitor.visit_region(*self)
 966     }
 967 }
 968
 969 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
 970     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 971         let new = self.inner.kind.fold_with(folder);
 972         folder.tcx().reuse_or_mk_predicate(self, new)
 973     }
 974
 975     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 976         self.inner.kind.visit_with(visitor)
 977     }
 978
 979     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 980         visitor.visit_predicate(*self)
 981     }
 982
 983     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
 984         self.inner.outer_exclusive_binder > binder
 985     }
 986
 987     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
 988         self.inner.flags.intersects(flags)
 989     }
 990 }
 991
 992 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
 993     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 994         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
 995     }
 996
 997     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 998         self.iter().try_for_each(|p| p.visit_with(visitor))
 999     }
1000 }
1001
1002 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1003     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1004         self.map_id(|x| x.fold_with(folder))
1005     }
1006
1007     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1008         self.iter().try_for_each(|t| t.visit_with(visitor))
1009     }
1010 }
1011
1012 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1013     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1014         let ty = self.ty.fold_with(folder);
1015         let val = self.val.fold_with(folder);
1016         if ty != self.ty || val != self.val {
1017             folder.tcx().mk_const(ty::Const { ty, val })
1018         } else {
1019             self
1020         }
1021     }
1022
1023     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1024         folder.fold_const(self)
1025     }
1026
1027     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1028         self.ty.visit_with(visitor)?;
1029         self.val.visit_with(visitor)
1030     }
1031
1032     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1033         visitor.visit_const(self)
1034     }
1035 }
1036
1037 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1038     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1039         match self {
1040             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
1041             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
1042             ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }) => {
1043                 ty::ConstKind::Unevaluated(ty::Unevaluated {
1044                     def,
1045                     substs: substs.fold_with(folder),
1046                     promoted,
1047                 })
1048             }
1049             ty::ConstKind::Value(_)
1050             | ty::ConstKind::Bound(..)
1051             | ty::ConstKind::Placeholder(..)
1052             | ty::ConstKind::Error(_) => self,
1053         }
1054     }
1055
1056     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1057         match *self {
1058             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1059             ty::ConstKind::Param(p) => p.visit_with(visitor),
1060             ty::ConstKind::Unevaluated(ct) => ct.substs.visit_with(visitor),
1061             ty::ConstKind::Value(_)
1062             | ty::ConstKind::Bound(..)
1063             | ty::ConstKind::Placeholder(_)
1064             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1065         }
1066     }
1067 }
1068
1069 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1070     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
1071         self
1072     }
1073
1074     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1075         ControlFlow::CONTINUE
1076     }
1077 }