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::def::Namespace;
  12 use rustc_hir::def_id::CRATE_DEF_INDEX;
  13 use rustc_index::vec::{Idx, IndexVec};
  14
  15 use std::fmt;
  16 use std::ops::ControlFlow;
  17 use std::rc::Rc;
  18 use std::sync::Arc;
  19
  20 impl fmt::Debug for ty::TraitDef {
  21     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  22         ty::tls::with(|tcx| {
  23             with_no_trimmed_paths(|| {
  24                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.def_id, &[])
  25             })?;
  26             Ok(())
  27         })
  28     }
  29 }
  30
  31 impl fmt::Debug for ty::AdtDef {
  32     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  33         ty::tls::with(|tcx| {
  34             with_no_trimmed_paths(|| {
  35                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.did, &[])
  36             })?;
  37             Ok(())
  38         })
  39     }
  40 }
  41
  42 impl fmt::Debug for ty::UpvarId {
  43     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  44         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  45         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  46     }
  47 }
  48
  49 impl fmt::Debug for ty::UpvarBorrow<'tcx> {
  50     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  51         write!(f, "UpvarBorrow({:?}, {:?})", self.kind, self.region)
  52     }
  53 }
  54
  55 impl fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  56     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  57         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
  58     }
  59 }
  60
  61 impl fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  62     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  63         write!(f, "{:?} -> {}", self.kind, self.target)
  64     }
  65 }
  66
  67 impl fmt::Debug for ty::BoundRegionKind {
  68     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  69         match *self {
  70             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  71             ty::BrNamed(did, name) => {
  72                 if did.index == CRATE_DEF_INDEX {
  73                     write!(f, "BrNamed({})", name)
  74                 } else {
  75                     write!(f, "BrNamed({:?}, {})", did, name)
  76                 }
  77             }
  78             ty::BrEnv => write!(f, "BrEnv"),
  79         }
  80     }
  81 }
  82
  83 impl fmt::Debug for ty::RegionKind {
  84     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  85         match *self {
  86             ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name),
  87
  88             ty::ReLateBound(binder_id, ref bound_region) => {
  89                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
  90             }
  91
  92             ty::ReFree(ref fr) => fr.fmt(f),
  93
  94             ty::ReStatic => write!(f, "ReStatic"),
  95
  96             ty::ReVar(ref vid) => vid.fmt(f),
  97
  98             ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder),
  99
 100             ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui),
 101
 102             ty::ReErased => write!(f, "ReErased"),
 103         }
 104     }
 105 }
 106
 107 impl fmt::Debug for ty::FreeRegion {
 108     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 109         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 110     }
 111 }
 112
 113 impl fmt::Debug for ty::FnSig<'tcx> {
 114     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 115         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 116     }
 117 }
 118
 119 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 120     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 121         write!(f, "_#{}c", self.index)
 122     }
 123 }
 124
 125 impl fmt::Debug for ty::RegionVid {
 126     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 127         write!(f, "'_#{}r", self.index())
 128     }
 129 }
 130
 131 impl fmt::Debug for ty::TraitRef<'tcx> {
 132     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 133         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 134     }
 135 }
 136
 137 impl fmt::Debug for Ty<'tcx> {
 138     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 139         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 140     }
 141 }
 142
 143 impl fmt::Debug for ty::ParamTy {
 144     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 145         write!(f, "{}/#{}", self.name, self.index)
 146     }
 147 }
 148
 149 impl fmt::Debug for ty::ParamConst {
 150     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 151         write!(f, "{}/#{}", self.name, self.index)
 152     }
 153 }
 154
 155 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 156     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 157         if let ty::BoundConstness::ConstIfConst = self.constness {
 158             write!(f, "~const ")?;
 159         }
 160         write!(f, "TraitPredicate({:?}, polarity:{:?})", self.trait_ref, self.polarity)
 161     }
 162 }
 163
 164 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 165     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 166         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 167     }
 168 }
 169
 170 impl fmt::Debug for ty::Predicate<'tcx> {
 171     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 172         write!(f, "{:?}", self.kind())
 173     }
 174 }
 175
 176 impl fmt::Debug for ty::PredicateKind<'tcx> {
 177     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 178         match *self {
 179             ty::PredicateKind::Trait(ref a) => a.fmt(f),
 180             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 181             ty::PredicateKind::Coerce(ref pair) => pair.fmt(f),
 182             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 183             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 184             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 185             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 186             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 187                 write!(f, "ObjectSafe({:?})", trait_def_id)
 188             }
 189             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 190                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 191             }
 192             ty::PredicateKind::ConstEvaluatable(uv) => {
 193                 write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs_)
 194             }
 195             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 196             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 197                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 198             }
 199         }
 200     }
 201 }
 202
 203 ///////////////////////////////////////////////////////////////////////////
 204 // Atomic structs
 205 //
 206 // For things that don't carry any arena-allocated data (and are
 207 // copy...), just add them to this list.
 208
 209 TrivialTypeFoldableAndLiftImpls! {
 210     (),
 211     bool,
 212     usize,
 213     ::rustc_target::abi::VariantIdx,
 214     u32,
 215     u64,
 216     String,
 217     crate::middle::region::Scope,
 218     crate::ty::FloatTy,
 219     ::rustc_ast::InlineAsmOptions,
 220     ::rustc_ast::InlineAsmTemplatePiece,
 221     ::rustc_ast::NodeId,
 222     ::rustc_span::symbol::Symbol,
 223     ::rustc_hir::def::Res,
 224     ::rustc_hir::def_id::DefId,
 225     ::rustc_hir::def_id::LocalDefId,
 226     ::rustc_hir::HirId,
 227     ::rustc_hir::LlvmInlineAsmInner,
 228     ::rustc_hir::MatchSource,
 229     ::rustc_hir::Mutability,
 230     ::rustc_hir::Unsafety,
 231     ::rustc_target::asm::InlineAsmRegOrRegClass,
 232     ::rustc_target::spec::abi::Abi,
 233     crate::mir::coverage::ExpressionOperandId,
 234     crate::mir::coverage::CounterValueReference,
 235     crate::mir::coverage::InjectedExpressionId,
 236     crate::mir::coverage::InjectedExpressionIndex,
 237     crate::mir::coverage::MappedExpressionIndex,
 238     crate::mir::Local,
 239     crate::mir::Promoted,
 240     crate::traits::Reveal,
 241     crate::ty::adjustment::AutoBorrowMutability,
 242     crate::ty::AdtKind,
 243     crate::ty::BoundConstness,
 244     // Including `BoundRegionKind` is a *bit* dubious, but direct
 245     // references to bound region appear in `ty::Error`, and aren't
 246     // really meant to be folded. In general, we can only fold a fully
 247     // general `Region`.
 248     crate::ty::BoundRegionKind,
 249     crate::ty::AssocItem,
 250     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 251     crate::ty::ClosureKind,
 252     crate::ty::FreeRegion,
 253     crate::ty::InferTy,
 254     crate::ty::IntVarValue,
 255     crate::ty::ParamConst,
 256     crate::ty::ParamTy,
 257     crate::ty::adjustment::PointerCast,
 258     crate::ty::RegionVid,
 259     crate::ty::UniverseIndex,
 260     crate::ty::Variance,
 261     ::rustc_span::Span,
 262 }
 263
 264 ///////////////////////////////////////////////////////////////////////////
 265 // Lift implementations
 266
 267 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 268 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 269     type Lifted = (A::Lifted, B::Lifted);
 270     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 271         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 272     }
 273 }
 274
 275 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 276     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 277     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 278         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 279     }
 280 }
 281
 282 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 283     type Lifted = Option<T::Lifted>;
 284     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 285         match self {
 286             Some(x) => tcx.lift(x).map(Some),
 287             None => Some(None),
 288         }
 289     }
 290 }
 291
 292 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 293     type Lifted = Result<T::Lifted, E::Lifted>;
 294     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 295         match self {
 296             Ok(x) => tcx.lift(x).map(Ok),
 297             Err(e) => tcx.lift(e).map(Err),
 298         }
 299     }
 300 }
 301
 302 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 303     type Lifted = Box<T::Lifted>;
 304     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 305         tcx.lift(*self).map(Box::new)
 306     }
 307 }
 308
 309 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 310     type Lifted = Rc<T::Lifted>;
 311     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 312         tcx.lift(self.as_ref().clone()).map(Rc::new)
 313     }
 314 }
 315
 316 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 317     type Lifted = Arc<T::Lifted>;
 318     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 319         tcx.lift(self.as_ref().clone()).map(Arc::new)
 320     }
 321 }
 322 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 323     type Lifted = Vec<T::Lifted>;
 324     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 325         self.into_iter().map(|v| tcx.lift(v)).collect()
 326     }
 327 }
 328
 329 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 330     type Lifted = IndexVec<I, T::Lifted>;
 331     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 332         self.into_iter().map(|e| tcx.lift(e)).collect()
 333     }
 334 }
 335
 336 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 337     type Lifted = ty::TraitRef<'tcx>;
 338     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 339         tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 340     }
 341 }
 342
 343 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 344     type Lifted = ty::ExistentialTraitRef<'tcx>;
 345     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 346         tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 347     }
 348 }
 349
 350 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 351     type Lifted = ty::ExistentialPredicate<'tcx>;
 352     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 353         match self {
 354             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 355             ty::ExistentialPredicate::Projection(x) => {
 356                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 357             }
 358             ty::ExistentialPredicate::AutoTrait(def_id) => {
 359                 Some(ty::ExistentialPredicate::AutoTrait(def_id))
 360             }
 361         }
 362     }
 363 }
 364
 365 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 366     type Lifted = ty::TraitPredicate<'tcx>;
 367     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 368         tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 369             trait_ref,
 370             constness: self.constness,
 371             polarity: self.polarity,
 372         })
 373     }
 374 }
 375
 376 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 377     type Lifted = ty::SubtypePredicate<'tcx>;
 378     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 379         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 380             a_is_expected: self.a_is_expected,
 381             a,
 382             b,
 383         })
 384     }
 385 }
 386
 387 impl<'a, 'tcx> Lift<'tcx> for ty::CoercePredicate<'a> {
 388     type Lifted = ty::CoercePredicate<'tcx>;
 389     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::CoercePredicate<'tcx>> {
 390         tcx.lift((self.a, self.b)).map(|(a, b)| ty::CoercePredicate { a, b })
 391     }
 392 }
 393
 394 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 395     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 396     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 397         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 398     }
 399 }
 400
 401 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 402     type Lifted = ty::ProjectionTy<'tcx>;
 403     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 404         tcx.lift(self.substs)
 405             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 406     }
 407 }
 408
 409 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 410     type Lifted = ty::ProjectionPredicate<'tcx>;
 411     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 412         tcx.lift((self.projection_ty, self.ty))
 413             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 414     }
 415 }
 416
 417 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 418     type Lifted = ty::ExistentialProjection<'tcx>;
 419     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 420         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 421             substs,
 422             ty: tcx.lift(self.ty).expect("type must lift when substs do"),
 423             item_def_id: self.item_def_id,
 424         })
 425     }
 426 }
 427
 428 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 429     type Lifted = ty::PredicateKind<'tcx>;
 430     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 431         match self {
 432             ty::PredicateKind::Trait(data) => tcx.lift(data).map(ty::PredicateKind::Trait),
 433             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 434             ty::PredicateKind::Coerce(data) => tcx.lift(data).map(ty::PredicateKind::Coerce),
 435             ty::PredicateKind::RegionOutlives(data) => {
 436                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 437             }
 438             ty::PredicateKind::TypeOutlives(data) => {
 439                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 440             }
 441             ty::PredicateKind::Projection(data) => {
 442                 tcx.lift(data).map(ty::PredicateKind::Projection)
 443             }
 444             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 445             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 446                 tcx.lift(closure_substs).map(|closure_substs| {
 447                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 448                 })
 449             }
 450             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 451                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 452             }
 453             ty::PredicateKind::ConstEvaluatable(uv) => {
 454                 tcx.lift(uv).map(|uv| ty::PredicateKind::ConstEvaluatable(uv))
 455             }
 456             ty::PredicateKind::ConstEquate(c1, c2) => {
 457                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 458             }
 459             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 460                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 461             }
 462         }
 463     }
 464 }
 465
 466 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 467 where
 468     <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>,
 469 {
 470     type Lifted = ty::Binder<'tcx, T::Lifted>;
 471     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 472         let bound_vars = tcx.lift(self.bound_vars());
 473         tcx.lift(self.skip_binder())
 474             .zip(bound_vars)
 475             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 476     }
 477 }
 478
 479 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 480     type Lifted = ty::ParamEnv<'tcx>;
 481     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 482         tcx.lift(self.caller_bounds())
 483             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
 484     }
 485 }
 486
 487 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 488     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 489     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 490         tcx.lift(self.param_env).and_then(|param_env| {
 491             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 492         })
 493     }
 494 }
 495
 496 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 497     type Lifted = ty::ClosureSubsts<'tcx>;
 498     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 499         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 500     }
 501 }
 502
 503 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 504     type Lifted = ty::GeneratorSubsts<'tcx>;
 505     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 506         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 507     }
 508 }
 509
 510 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 511     type Lifted = ty::adjustment::Adjustment<'tcx>;
 512     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 513         let ty::adjustment::Adjustment { kind, target } = self;
 514         tcx.lift(kind).and_then(|kind| {
 515             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 516         })
 517     }
 518 }
 519
 520 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 521     type Lifted = ty::adjustment::Adjust<'tcx>;
 522     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 523         match self {
 524             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 525             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 526             ty::adjustment::Adjust::Deref(overloaded) => {
 527                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 528             }
 529             ty::adjustment::Adjust::Borrow(autoref) => {
 530                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 531             }
 532         }
 533     }
 534 }
 535
 536 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 537     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 538     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 539         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 540             region,
 541             mutbl: self.mutbl,
 542             span: self.span,
 543         })
 544     }
 545 }
 546
 547 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 548     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 549     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 550         match self {
 551             ty::adjustment::AutoBorrow::Ref(r, m) => {
 552                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 553             }
 554             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 555         }
 556     }
 557 }
 558
 559 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 560     type Lifted = ty::GenSig<'tcx>;
 561     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 562         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 563             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 564     }
 565 }
 566
 567 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 568     type Lifted = ty::FnSig<'tcx>;
 569     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 570         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 571             inputs_and_output: x,
 572             c_variadic: self.c_variadic,
 573             unsafety: self.unsafety,
 574             abi: self.abi,
 575         })
 576     }
 577 }
 578
 579 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 580     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 581     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 582         let ty::error::ExpectedFound { expected, found } = self;
 583         tcx.lift(expected).and_then(|expected| {
 584             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 585         })
 586     }
 587 }
 588
 589 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 590     type Lifted = ty::error::TypeError<'tcx>;
 591     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 592         use crate::ty::error::TypeError::*;
 593
 594         Some(match self {
 595             Mismatch => Mismatch,
 596             ConstnessMismatch(x) => ConstnessMismatch(x),
 597             PolarityMismatch(x) => PolarityMismatch(x),
 598             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 599             AbiMismatch(x) => AbiMismatch(x),
 600             Mutability => Mutability,
 601             ArgumentMutability(i) => ArgumentMutability(i),
 602             TupleSize(x) => TupleSize(x),
 603             FixedArraySize(x) => FixedArraySize(x),
 604             ArgCount => ArgCount,
 605             FieldMisMatch(x, y) => FieldMisMatch(x, y),
 606             RegionsDoesNotOutlive(a, b) => {
 607                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 608             }
 609             RegionsInsufficientlyPolymorphic(a, b) => {
 610                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 611             }
 612             RegionsOverlyPolymorphic(a, b) => {
 613                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 614             }
 615             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 616             IntMismatch(x) => IntMismatch(x),
 617             FloatMismatch(x) => FloatMismatch(x),
 618             Traits(x) => Traits(x),
 619             VariadicMismatch(x) => VariadicMismatch(x),
 620             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 621             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 622             ProjectionMismatched(x) => ProjectionMismatched(x),
 623             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 624             Sorts(x) => return tcx.lift(x).map(Sorts),
 625             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 626             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 627             IntrinsicCast => IntrinsicCast,
 628             TargetFeatureCast(x) => TargetFeatureCast(x),
 629             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 630         })
 631     }
 632 }
 633
 634 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 635     type Lifted = ty::InstanceDef<'tcx>;
 636     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 637         match self {
 638             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 639             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 640             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 641             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 642             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 643                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 644             }
 645             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 646             ty::InstanceDef::ClosureOnceShim { call_once, track_caller } => {
 647                 Some(ty::InstanceDef::ClosureOnceShim { call_once, track_caller })
 648             }
 649             ty::InstanceDef::DropGlue(def_id, ty) => {
 650                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 651             }
 652             ty::InstanceDef::CloneShim(def_id, ty) => {
 653                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 654             }
 655         }
 656     }
 657 }
 658
 659 ///////////////////////////////////////////////////////////////////////////
 660 // TypeFoldable implementations.
 661 //
 662 // Ideally, each type should invoke `folder.fold_foo(self)` and
 663 // nothing else. In some cases, though, we haven't gotten around to
 664 // adding methods on the `folder` yet, and thus the folding is
 665 // hard-coded here. This is less-flexible, because folders cannot
 666 // override the behavior, but there are a lot of random types and one
 667 // can easily refactor the folding into the TypeFolder trait as
 668 // needed.
 669
 670 /// AdtDefs are basically the same as a DefId.
 671 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 672     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 673         self
 674     }
 675
 676     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 677         ControlFlow::CONTINUE
 678     }
 679 }
 680
 681 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 682     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (T, U) {
 683         (self.0.fold_with(folder), self.1.fold_with(folder))
 684     }
 685
 686     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 687         self.0.visit_with(visitor)?;
 688         self.1.visit_with(visitor)
 689     }
 690 }
 691
 692 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 693     for (A, B, C)
 694 {
 695     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (A, B, C) {
 696         (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
 697     }
 698
 699     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 700         self.0.visit_with(visitor)?;
 701         self.1.visit_with(visitor)?;
 702         self.2.visit_with(visitor)
 703     }
 704 }
 705
 706 EnumTypeFoldableImpl! {
 707     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 708         (Some)(a),
 709         (None),
 710     } where T: TypeFoldable<'tcx>
 711 }
 712
 713 EnumTypeFoldableImpl! {
 714     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 715         (Ok)(a),
 716         (Err)(a),
 717     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 718 }
 719
 720 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 721     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 722         // FIXME: Reuse the `Rc` here.
 723         Rc::new((*self).clone().fold_with(folder))
 724     }
 725
 726     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 727         (**self).visit_with(visitor)
 728     }
 729 }
 730
 731 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 732     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 733         // FIXME: Reuse the `Arc` here.
 734         Arc::new((*self).clone().fold_with(folder))
 735     }
 736
 737     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 738         (**self).visit_with(visitor)
 739     }
 740 }
 741
 742 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 743     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 744         self.map_id(|value| value.fold_with(folder))
 745     }
 746
 747     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 748         (**self).visit_with(visitor)
 749     }
 750 }
 751
 752 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 753     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 754         self.map_id(|t| t.fold_with(folder))
 755     }
 756
 757     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 758         self.iter().try_for_each(|t| t.visit_with(visitor))
 759     }
 760 }
 761
 762 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 763     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 764         self.map_id(|t| t.fold_with(folder))
 765     }
 766
 767     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 768         self.iter().try_for_each(|t| t.visit_with(visitor))
 769     }
 770 }
 771
 772 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 773     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 774         self.map_bound(|ty| ty.fold_with(folder))
 775     }
 776
 777     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 778         folder.fold_binder(self)
 779     }
 780
 781     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 782         self.as_ref().skip_binder().visit_with(visitor)
 783     }
 784
 785     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 786         visitor.visit_binder(self)
 787     }
 788 }
 789
 790 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 791     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 792         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 793     }
 794
 795     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 796         self.iter().try_for_each(|p| p.visit_with(visitor))
 797     }
 798 }
 799
 800 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 801     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 802         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_type_list(v))
 803     }
 804
 805     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 806         self.iter().try_for_each(|t| t.visit_with(visitor))
 807     }
 808 }
 809
 810 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 811     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 812         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 813     }
 814
 815     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 816         self.iter().try_for_each(|t| t.visit_with(visitor))
 817     }
 818 }
 819
 820 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 821     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 822         use crate::ty::InstanceDef::*;
 823         Self {
 824             substs: self.substs.fold_with(folder),
 825             def: match self.def {
 826                 Item(def) => Item(def.fold_with(folder)),
 827                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 828                 ReifyShim(did) => ReifyShim(did.fold_with(folder)),
 829                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 830                 FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)),
 831                 Virtual(did, i) => Virtual(did.fold_with(folder), i),
 832                 ClosureOnceShim { call_once, track_caller } => {
 833                     ClosureOnceShim { call_once: call_once.fold_with(folder), track_caller }
 834                 }
 835                 DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)),
 836                 CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)),
 837             },
 838         }
 839     }
 840
 841     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 842         use crate::ty::InstanceDef::*;
 843         self.substs.visit_with(visitor)?;
 844         match self.def {
 845             Item(def) => def.visit_with(visitor),
 846             VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 847                 did.visit_with(visitor)
 848             }
 849             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 850                 did.visit_with(visitor)?;
 851                 ty.visit_with(visitor)
 852             }
 853             DropGlue(did, ty) => {
 854                 did.visit_with(visitor)?;
 855                 ty.visit_with(visitor)
 856             }
 857             ClosureOnceShim { call_once, track_caller: _ } => call_once.visit_with(visitor),
 858         }
 859     }
 860 }
 861
 862 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 863     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 864         Self { instance: self.instance.fold_with(folder), promoted: self.promoted }
 865     }
 866
 867     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 868         self.instance.visit_with(visitor)
 869     }
 870 }
 871
 872 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 873     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 874         let kind = match *self.kind() {
 875             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 876             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
 877             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
 878             ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)),
 879             ty::Dynamic(trait_ty, region) => {
 880                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder))
 881             }
 882             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
 883             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.fold_with(folder)),
 884             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
 885             ty::Ref(r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl),
 886             ty::Generator(did, substs, movability) => {
 887                 ty::Generator(did, substs.fold_with(folder), movability)
 888             }
 889             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
 890             ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)),
 891             ty::Projection(data) => ty::Projection(data.fold_with(folder)),
 892             ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)),
 893
 894             ty::Bool
 895             | ty::Char
 896             | ty::Str
 897             | ty::Int(_)
 898             | ty::Uint(_)
 899             | ty::Float(_)
 900             | ty::Error(_)
 901             | ty::Infer(_)
 902             | ty::Param(..)
 903             | ty::Bound(..)
 904             | ty::Placeholder(..)
 905             | ty::Never
 906             | ty::Foreign(..) => return self,
 907         };
 908
 909         if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) }
 910     }
 911
 912     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 913         folder.fold_ty(self)
 914     }
 915
 916     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 917         match self.kind() {
 918             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 919             ty::Array(typ, sz) => {
 920                 typ.visit_with(visitor)?;
 921                 sz.visit_with(visitor)
 922             }
 923             ty::Slice(typ) => typ.visit_with(visitor),
 924             ty::Adt(_, substs) => substs.visit_with(visitor),
 925             ty::Dynamic(ref trait_ty, ref reg) => {
 926                 trait_ty.visit_with(visitor)?;
 927                 reg.visit_with(visitor)
 928             }
 929             ty::Tuple(ts) => ts.visit_with(visitor),
 930             ty::FnDef(_, substs) => substs.visit_with(visitor),
 931             ty::FnPtr(ref f) => f.visit_with(visitor),
 932             ty::Ref(r, ty, _) => {
 933                 r.visit_with(visitor)?;
 934                 ty.visit_with(visitor)
 935             }
 936             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 937             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 938             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 939             ty::Projection(ref data) => data.visit_with(visitor),
 940             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 941
 942             ty::Bool
 943             | ty::Char
 944             | ty::Str
 945             | ty::Int(_)
 946             | ty::Uint(_)
 947             | ty::Float(_)
 948             | ty::Error(_)
 949             | ty::Infer(_)
 950             | ty::Bound(..)
 951             | ty::Placeholder(..)
 952             | ty::Param(..)
 953             | ty::Never
 954             | ty::Foreign(..) => ControlFlow::CONTINUE,
 955         }
 956     }
 957
 958     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 959         visitor.visit_ty(self)
 960     }
 961 }
 962
 963 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
 964     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 965         self
 966     }
 967
 968     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 969         folder.fold_region(self)
 970     }
 971
 972     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 973         ControlFlow::CONTINUE
 974     }
 975
 976     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 977         visitor.visit_region(*self)
 978     }
 979 }
 980
 981 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
 982     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 983         folder.fold_predicate(self)
 984     }
 985
 986     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 987         let new = self.inner.kind.fold_with(folder);
 988         folder.tcx().reuse_or_mk_predicate(self, new)
 989     }
 990
 991     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 992         self.inner.kind.visit_with(visitor)
 993     }
 994
 995     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 996         visitor.visit_predicate(*self)
 997     }
 998
 999     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1000         self.inner.outer_exclusive_binder > binder
1001     }
1002
1003     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1004         self.inner.flags.intersects(flags)
1005     }
1006 }
1007
1008 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1009     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1010         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
1011     }
1012
1013     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1014         self.iter().try_for_each(|p| p.visit_with(visitor))
1015     }
1016 }
1017
1018 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1019     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1020         self.map_id(|x| x.fold_with(folder))
1021     }
1022
1023     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1024         self.iter().try_for_each(|t| t.visit_with(visitor))
1025     }
1026 }
1027
1028 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1029     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1030         let ty = self.ty.fold_with(folder);
1031         let val = self.val.fold_with(folder);
1032         if ty != self.ty || val != self.val {
1033             folder.tcx().mk_const(ty::Const { ty, val })
1034         } else {
1035             self
1036         }
1037     }
1038
1039     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1040         folder.fold_const(self)
1041     }
1042
1043     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1044         self.ty.visit_with(visitor)?;
1045         self.val.visit_with(visitor)
1046     }
1047
1048     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1049         visitor.visit_const(self)
1050     }
1051 }
1052
1053 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1054     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1055         match self {
1056             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
1057             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
1058             ty::ConstKind::Unevaluated(uv) => ty::ConstKind::Unevaluated(uv.fold_with(folder)),
1059             ty::ConstKind::Value(_)
1060             | ty::ConstKind::Bound(..)
1061             | ty::ConstKind::Placeholder(..)
1062             | ty::ConstKind::Error(_) => self,
1063         }
1064     }
1065
1066     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1067         match *self {
1068             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1069             ty::ConstKind::Param(p) => p.visit_with(visitor),
1070             ty::ConstKind::Unevaluated(uv) => uv.visit_with(visitor),
1071             ty::ConstKind::Value(_)
1072             | ty::ConstKind::Bound(..)
1073             | ty::ConstKind::Placeholder(_)
1074             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1075         }
1076     }
1077 }
1078
1079 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1080     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
1081         self
1082     }
1083
1084     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1085         ControlFlow::CONTINUE
1086     }
1087 }
1088
1089 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
1090     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1091         ty::Unevaluated {
1092             def: self.def,
1093             substs_: Some(self.substs(folder.tcx()).fold_with(folder)),
1094             promoted: self.promoted,
1095         }
1096     }
1097
1098     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1099         visitor.visit_unevaluated_const(*self)
1100     }
1101
1102     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1103         if let Some(tcx) = visitor.tcx_for_anon_const_substs() {
1104             self.substs(tcx).visit_with(visitor)
1105         } else if let Some(substs) = self.substs_ {
1106             substs.visit_with(visitor)
1107         } else {
1108             debug!("ignoring default substs of `{:?}`", self.def);
1109             ControlFlow::CONTINUE
1110         }
1111     }
1112 }
1113
1114 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
1115     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1116         ty::Unevaluated {
1117             def: self.def,
1118             substs_: Some(self.substs(folder.tcx()).fold_with(folder)),
1119             promoted: self.promoted,
1120         }
1121     }
1122
1123     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1124         visitor.visit_unevaluated_const(self.expand())
1125     }
1126
1127     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1128         if let Some(tcx) = visitor.tcx_for_anon_const_substs() {
1129             self.substs(tcx).visit_with(visitor)
1130         } else if let Some(substs) = self.substs_ {
1131             substs.visit_with(visitor)
1132         } else {
1133             debug!("ignoring default substs of `{:?}`", self.def);
1134             ControlFlow::CONTINUE
1135         }
1136     }
1137 }