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::{FallibleTypeFolder, TypeFoldable, 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::mem::ManuallyDrop;
  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<'tcx> fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  51     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  52         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
  53     }
  54 }
  55
  56 impl<'tcx> fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  57     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  58         write!(f, "{:?} -> {}", self.kind, self.target)
  59     }
  60 }
  61
  62 impl fmt::Debug for ty::BoundRegionKind {
  63     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  64         match *self {
  65             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  66             ty::BrNamed(did, name) => {
  67                 if did.index == CRATE_DEF_INDEX {
  68                     write!(f, "BrNamed({})", name)
  69                 } else {
  70                     write!(f, "BrNamed({:?}, {})", did, name)
  71                 }
  72             }
  73             ty::BrEnv => write!(f, "BrEnv"),
  74         }
  75     }
  76 }
  77
  78 impl fmt::Debug for ty::RegionKind {
  79     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  80         match *self {
  81             ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name),
  82
  83             ty::ReLateBound(binder_id, ref bound_region) => {
  84                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
  85             }
  86
  87             ty::ReFree(ref fr) => fr.fmt(f),
  88
  89             ty::ReStatic => write!(f, "ReStatic"),
  90
  91             ty::ReVar(ref vid) => vid.fmt(f),
  92
  93             ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder),
  94
  95             ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui),
  96
  97             ty::ReErased => write!(f, "ReErased"),
  98         }
  99     }
 100 }
 101
 102 impl fmt::Debug for ty::FreeRegion {
 103     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 104         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 105     }
 106 }
 107
 108 impl<'tcx> fmt::Debug for ty::FnSig<'tcx> {
 109     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 110         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 111     }
 112 }
 113
 114 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 115     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 116         write!(f, "_#{}c", self.index)
 117     }
 118 }
 119
 120 impl fmt::Debug for ty::RegionVid {
 121     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 122         write!(f, "'_#{}r", self.index())
 123     }
 124 }
 125
 126 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
 127     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 128         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 129     }
 130 }
 131
 132 impl<'tcx> fmt::Debug for Ty<'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::ParamTy {
 139     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 140         write!(f, "{}/#{}", self.name, self.index)
 141     }
 142 }
 143
 144 impl fmt::Debug for ty::ParamConst {
 145     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 146         write!(f, "{}/#{}", self.name, self.index)
 147     }
 148 }
 149
 150 impl<'tcx> fmt::Debug for ty::TraitPredicate<'tcx> {
 151     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 152         if let ty::BoundConstness::ConstIfConst = self.constness {
 153             write!(f, "~const ")?;
 154         }
 155         write!(f, "TraitPredicate({:?}, polarity:{:?})", self.trait_ref, self.polarity)
 156     }
 157 }
 158
 159 impl<'tcx> fmt::Debug for ty::ProjectionPredicate<'tcx> {
 160     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 161         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 162     }
 163 }
 164
 165 impl<'tcx> fmt::Debug for ty::Predicate<'tcx> {
 166     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 167         write!(f, "{:?}", self.kind())
 168     }
 169 }
 170
 171 impl<'tcx> fmt::Debug for ty::PredicateKind<'tcx> {
 172     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 173         match *self {
 174             ty::PredicateKind::Trait(ref a) => a.fmt(f),
 175             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 176             ty::PredicateKind::Coerce(ref pair) => pair.fmt(f),
 177             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 178             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 179             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 180             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 181             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 182                 write!(f, "ObjectSafe({:?})", trait_def_id)
 183             }
 184             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 185                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 186             }
 187             ty::PredicateKind::ConstEvaluatable(uv) => {
 188                 write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs)
 189             }
 190             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 191             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 192                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 193             }
 194         }
 195     }
 196 }
 197
 198 ///////////////////////////////////////////////////////////////////////////
 199 // Atomic structs
 200 //
 201 // For things that don't carry any arena-allocated data (and are
 202 // copy...), just add them to this list.
 203
 204 TrivialTypeFoldableAndLiftImpls! {
 205     (),
 206     bool,
 207     usize,
 208     ::rustc_target::abi::VariantIdx,
 209     u32,
 210     u64,
 211     String,
 212     crate::middle::region::Scope,
 213     crate::ty::FloatTy,
 214     ::rustc_ast::InlineAsmOptions,
 215     ::rustc_ast::InlineAsmTemplatePiece,
 216     ::rustc_ast::NodeId,
 217     ::rustc_span::symbol::Symbol,
 218     ::rustc_hir::def::Res,
 219     ::rustc_hir::def_id::DefId,
 220     ::rustc_hir::def_id::LocalDefId,
 221     ::rustc_hir::HirId,
 222     ::rustc_hir::MatchSource,
 223     ::rustc_hir::Mutability,
 224     ::rustc_hir::Unsafety,
 225     ::rustc_target::asm::InlineAsmRegOrRegClass,
 226     ::rustc_target::spec::abi::Abi,
 227     crate::mir::coverage::ExpressionOperandId,
 228     crate::mir::coverage::CounterValueReference,
 229     crate::mir::coverage::InjectedExpressionId,
 230     crate::mir::coverage::InjectedExpressionIndex,
 231     crate::mir::coverage::MappedExpressionIndex,
 232     crate::mir::Local,
 233     crate::mir::Promoted,
 234     crate::traits::Reveal,
 235     crate::ty::adjustment::AutoBorrowMutability,
 236     crate::ty::AdtKind,
 237     crate::ty::BoundConstness,
 238     // Including `BoundRegionKind` is a *bit* dubious, but direct
 239     // references to bound region appear in `ty::Error`, and aren't
 240     // really meant to be folded. In general, we can only fold a fully
 241     // general `Region`.
 242     crate::ty::BoundRegionKind,
 243     crate::ty::AssocItem,
 244     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 245     crate::ty::ClosureKind,
 246     crate::ty::FreeRegion,
 247     crate::ty::InferTy,
 248     crate::ty::IntVarValue,
 249     crate::ty::ParamConst,
 250     crate::ty::ParamTy,
 251     crate::ty::adjustment::PointerCast,
 252     crate::ty::RegionVid,
 253     crate::ty::UniverseIndex,
 254     crate::ty::Variance,
 255     ::rustc_span::Span,
 256 }
 257
 258 ///////////////////////////////////////////////////////////////////////////
 259 // Lift implementations
 260
 261 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 262 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 263     type Lifted = (A::Lifted, B::Lifted);
 264     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 265         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 266     }
 267 }
 268
 269 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 270     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 271     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 272         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 273     }
 274 }
 275
 276 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 277     type Lifted = Option<T::Lifted>;
 278     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 279         match self {
 280             Some(x) => tcx.lift(x).map(Some),
 281             None => Some(None),
 282         }
 283     }
 284 }
 285
 286 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 287     type Lifted = Result<T::Lifted, E::Lifted>;
 288     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 289         match self {
 290             Ok(x) => tcx.lift(x).map(Ok),
 291             Err(e) => tcx.lift(e).map(Err),
 292         }
 293     }
 294 }
 295
 296 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 297     type Lifted = Box<T::Lifted>;
 298     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 299         tcx.lift(*self).map(Box::new)
 300     }
 301 }
 302
 303 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 304     type Lifted = Rc<T::Lifted>;
 305     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 306         tcx.lift(self.as_ref().clone()).map(Rc::new)
 307     }
 308 }
 309
 310 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 311     type Lifted = Arc<T::Lifted>;
 312     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 313         tcx.lift(self.as_ref().clone()).map(Arc::new)
 314     }
 315 }
 316 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 317     type Lifted = Vec<T::Lifted>;
 318     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 319         self.into_iter().map(|v| tcx.lift(v)).collect()
 320     }
 321 }
 322
 323 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 324     type Lifted = IndexVec<I, T::Lifted>;
 325     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 326         self.into_iter().map(|e| tcx.lift(e)).collect()
 327     }
 328 }
 329
 330 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 331     type Lifted = ty::TraitRef<'tcx>;
 332     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 333         tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 334     }
 335 }
 336
 337 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 338     type Lifted = ty::ExistentialTraitRef<'tcx>;
 339     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 340         tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 341     }
 342 }
 343
 344 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 345     type Lifted = ty::ExistentialPredicate<'tcx>;
 346     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 347         match self {
 348             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 349             ty::ExistentialPredicate::Projection(x) => {
 350                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 351             }
 352             ty::ExistentialPredicate::AutoTrait(def_id) => {
 353                 Some(ty::ExistentialPredicate::AutoTrait(def_id))
 354             }
 355         }
 356     }
 357 }
 358
 359 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 360     type Lifted = ty::TraitPredicate<'tcx>;
 361     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 362         tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 363             trait_ref,
 364             constness: self.constness,
 365             polarity: self.polarity,
 366         })
 367     }
 368 }
 369
 370 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 371     type Lifted = ty::SubtypePredicate<'tcx>;
 372     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 373         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 374             a_is_expected: self.a_is_expected,
 375             a,
 376             b,
 377         })
 378     }
 379 }
 380
 381 impl<'a, 'tcx> Lift<'tcx> for ty::CoercePredicate<'a> {
 382     type Lifted = ty::CoercePredicate<'tcx>;
 383     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::CoercePredicate<'tcx>> {
 384         tcx.lift((self.a, self.b)).map(|(a, b)| ty::CoercePredicate { a, b })
 385     }
 386 }
 387
 388 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 389     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 390     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 391         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 392     }
 393 }
 394
 395 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 396     type Lifted = ty::ProjectionTy<'tcx>;
 397     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 398         tcx.lift(self.substs)
 399             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 400     }
 401 }
 402
 403 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 404     type Lifted = ty::ProjectionPredicate<'tcx>;
 405     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 406         tcx.lift((self.projection_ty, self.ty))
 407             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 408     }
 409 }
 410
 411 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 412     type Lifted = ty::ExistentialProjection<'tcx>;
 413     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 414         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 415             substs,
 416             ty: tcx.lift(self.ty).expect("type must lift when substs do"),
 417             item_def_id: self.item_def_id,
 418         })
 419     }
 420 }
 421
 422 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 423     type Lifted = ty::PredicateKind<'tcx>;
 424     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 425         match self {
 426             ty::PredicateKind::Trait(data) => tcx.lift(data).map(ty::PredicateKind::Trait),
 427             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 428             ty::PredicateKind::Coerce(data) => tcx.lift(data).map(ty::PredicateKind::Coerce),
 429             ty::PredicateKind::RegionOutlives(data) => {
 430                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 431             }
 432             ty::PredicateKind::TypeOutlives(data) => {
 433                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 434             }
 435             ty::PredicateKind::Projection(data) => {
 436                 tcx.lift(data).map(ty::PredicateKind::Projection)
 437             }
 438             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 439             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 440                 tcx.lift(closure_substs).map(|closure_substs| {
 441                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 442                 })
 443             }
 444             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 445                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 446             }
 447             ty::PredicateKind::ConstEvaluatable(uv) => {
 448                 tcx.lift(uv).map(|uv| ty::PredicateKind::ConstEvaluatable(uv))
 449             }
 450             ty::PredicateKind::ConstEquate(c1, c2) => {
 451                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 452             }
 453             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 454                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 455             }
 456         }
 457     }
 458 }
 459
 460 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 461 where
 462     <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>,
 463 {
 464     type Lifted = ty::Binder<'tcx, T::Lifted>;
 465     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 466         let bound_vars = tcx.lift(self.bound_vars());
 467         tcx.lift(self.skip_binder())
 468             .zip(bound_vars)
 469             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 470     }
 471 }
 472
 473 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 474     type Lifted = ty::ParamEnv<'tcx>;
 475     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 476         tcx.lift(self.caller_bounds())
 477             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.constness()))
 478     }
 479 }
 480
 481 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 482     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 483     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 484         tcx.lift(self.param_env).and_then(|param_env| {
 485             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 486         })
 487     }
 488 }
 489
 490 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 491     type Lifted = ty::ClosureSubsts<'tcx>;
 492     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 493         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 494     }
 495 }
 496
 497 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 498     type Lifted = ty::GeneratorSubsts<'tcx>;
 499     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 500         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 501     }
 502 }
 503
 504 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 505     type Lifted = ty::adjustment::Adjustment<'tcx>;
 506     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 507         let ty::adjustment::Adjustment { kind, target } = self;
 508         tcx.lift(kind).and_then(|kind| {
 509             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 510         })
 511     }
 512 }
 513
 514 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 515     type Lifted = ty::adjustment::Adjust<'tcx>;
 516     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 517         match self {
 518             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 519             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 520             ty::adjustment::Adjust::Deref(overloaded) => {
 521                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 522             }
 523             ty::adjustment::Adjust::Borrow(autoref) => {
 524                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 525             }
 526         }
 527     }
 528 }
 529
 530 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 531     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 532     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 533         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 534             region,
 535             mutbl: self.mutbl,
 536             span: self.span,
 537         })
 538     }
 539 }
 540
 541 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 542     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 543     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 544         match self {
 545             ty::adjustment::AutoBorrow::Ref(r, m) => {
 546                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 547             }
 548             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 549         }
 550     }
 551 }
 552
 553 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 554     type Lifted = ty::GenSig<'tcx>;
 555     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 556         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 557             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 558     }
 559 }
 560
 561 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 562     type Lifted = ty::FnSig<'tcx>;
 563     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 564         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 565             inputs_and_output: x,
 566             c_variadic: self.c_variadic,
 567             unsafety: self.unsafety,
 568             abi: self.abi,
 569         })
 570     }
 571 }
 572
 573 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 574     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 575     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 576         let ty::error::ExpectedFound { expected, found } = self;
 577         tcx.lift(expected).and_then(|expected| {
 578             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 579         })
 580     }
 581 }
 582
 583 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 584     type Lifted = ty::error::TypeError<'tcx>;
 585     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 586         use crate::ty::error::TypeError::*;
 587
 588         Some(match self {
 589             Mismatch => Mismatch,
 590             ConstnessMismatch(x) => ConstnessMismatch(x),
 591             PolarityMismatch(x) => PolarityMismatch(x),
 592             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 593             AbiMismatch(x) => AbiMismatch(x),
 594             Mutability => Mutability,
 595             ArgumentMutability(i) => ArgumentMutability(i),
 596             TupleSize(x) => TupleSize(x),
 597             FixedArraySize(x) => FixedArraySize(x),
 598             ArgCount => ArgCount,
 599             FieldMisMatch(x, y) => FieldMisMatch(x, y),
 600             RegionsDoesNotOutlive(a, b) => {
 601                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 602             }
 603             RegionsInsufficientlyPolymorphic(a, b) => {
 604                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 605             }
 606             RegionsOverlyPolymorphic(a, b) => {
 607                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 608             }
 609             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 610             IntMismatch(x) => IntMismatch(x),
 611             FloatMismatch(x) => FloatMismatch(x),
 612             Traits(x) => Traits(x),
 613             VariadicMismatch(x) => VariadicMismatch(x),
 614             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 615             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 616             ProjectionMismatched(x) => ProjectionMismatched(x),
 617             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 618             Sorts(x) => return tcx.lift(x).map(Sorts),
 619             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 620             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 621             IntrinsicCast => IntrinsicCast,
 622             TargetFeatureCast(x) => TargetFeatureCast(x),
 623             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 624         })
 625     }
 626 }
 627
 628 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 629     type Lifted = ty::InstanceDef<'tcx>;
 630     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 631         match self {
 632             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 633             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 634             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 635             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 636             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 637                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 638             }
 639             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 640             ty::InstanceDef::ClosureOnceShim { call_once, track_caller } => {
 641                 Some(ty::InstanceDef::ClosureOnceShim { call_once, track_caller })
 642             }
 643             ty::InstanceDef::DropGlue(def_id, ty) => {
 644                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 645             }
 646             ty::InstanceDef::CloneShim(def_id, ty) => {
 647                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 648             }
 649         }
 650     }
 651 }
 652
 653 ///////////////////////////////////////////////////////////////////////////
 654 // TypeFoldable implementations.
 655 //
 656 // Ideally, each type should invoke `folder.fold_foo(self)` and
 657 // nothing else. In some cases, though, we haven't gotten around to
 658 // adding methods on the `folder` yet, and thus the folding is
 659 // hard-coded here. This is less-flexible, because folders cannot
 660 // override the behavior, but there are a lot of random types and one
 661 // can easily refactor the folding into the TypeFolder trait as
 662 // needed.
 663
 664 /// AdtDefs are basically the same as a DefId.
 665 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 666     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 667         self,
 668         _folder: &mut F,
 669     ) -> Result<Self, F::Error> {
 670         Ok(self)
 671     }
 672
 673     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 674         ControlFlow::CONTINUE
 675     }
 676 }
 677
 678 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 679     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 680         self,
 681         folder: &mut F,
 682     ) -> Result<(T, U), F::Error> {
 683         Ok((self.0.try_fold_with(folder)?, self.1.try_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 try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 696         self,
 697         folder: &mut F,
 698     ) -> Result<(A, B, C), F::Error> {
 699         Ok((
 700             self.0.try_fold_with(folder)?,
 701             self.1.try_fold_with(folder)?,
 702             self.2.try_fold_with(folder)?,
 703         ))
 704     }
 705
 706     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 707         self.0.visit_with(visitor)?;
 708         self.1.visit_with(visitor)?;
 709         self.2.visit_with(visitor)
 710     }
 711 }
 712
 713 EnumTypeFoldableImpl! {
 714     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 715         (Some)(a),
 716         (None),
 717     } where T: TypeFoldable<'tcx>
 718 }
 719
 720 EnumTypeFoldableImpl! {
 721     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 722         (Ok)(a),
 723         (Err)(a),
 724     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 725 }
 726
 727 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 728     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 729         mut self,
 730         folder: &mut F,
 731     ) -> Result<Self, F::Error> {
 732         // We merely want to replace the contained `T`, if at all possible,
 733         // so that we don't needlessly allocate a new `Rc` or indeed clone
 734         // the contained type.
 735         unsafe {
 736             // First step is to ensure that we have a unique reference to
 737             // the contained type, which `Rc::make_mut` will accomplish (by
 738             // allocating a new `Rc` and cloning the `T` only if required).
 739             // This is done *before* casting to `Rc<ManuallyDrop<T>>` so that
 740             // panicking during `make_mut` does not leak the `T`.
 741             Rc::make_mut(&mut self);
 742
 743             // Casting to `Rc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 744             // is `repr(transparent)`.
 745             let ptr = Rc::into_raw(self).cast::<ManuallyDrop<T>>();
 746             let mut unique = Rc::from_raw(ptr);
 747
 748             // Call to `Rc::make_mut` above guarantees that `unique` is the
 749             // sole reference to the contained value, so we can avoid doing
 750             // a checked `get_mut` here.
 751             let slot = Rc::get_mut_unchecked(&mut unique);
 752
 753             // Semantically move the contained type out from `unique`, fold
 754             // it, then move the folded value back into `unique`.  Should
 755             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 756             // value is not re-dropped.
 757             let owned = ManuallyDrop::take(slot);
 758             let folded = owned.try_fold_with(folder)?;
 759             *slot = ManuallyDrop::new(folded);
 760
 761             // Cast back to `Rc<T>`.
 762             Ok(Rc::from_raw(Rc::into_raw(unique).cast()))
 763         }
 764     }
 765
 766     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 767         (**self).visit_with(visitor)
 768     }
 769 }
 770
 771 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 772     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 773         mut self,
 774         folder: &mut F,
 775     ) -> Result<Self, F::Error> {
 776         // We merely want to replace the contained `T`, if at all possible,
 777         // so that we don't needlessly allocate a new `Arc` or indeed clone
 778         // the contained type.
 779         unsafe {
 780             // First step is to ensure that we have a unique reference to
 781             // the contained type, which `Arc::make_mut` will accomplish (by
 782             // allocating a new `Arc` and cloning the `T` only if required).
 783             // This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
 784             // panicking during `make_mut` does not leak the `T`.
 785             Arc::make_mut(&mut self);
 786
 787             // Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 788             // is `repr(transparent)`.
 789             let ptr = Arc::into_raw(self).cast::<ManuallyDrop<T>>();
 790             let mut unique = Arc::from_raw(ptr);
 791
 792             // Call to `Arc::make_mut` above guarantees that `unique` is the
 793             // sole reference to the contained value, so we can avoid doing
 794             // a checked `get_mut` here.
 795             let slot = Arc::get_mut_unchecked(&mut unique);
 796
 797             // Semantically move the contained type out from `unique`, fold
 798             // it, then move the folded value back into `unique`.  Should
 799             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 800             // value is not re-dropped.
 801             let owned = ManuallyDrop::take(slot);
 802             let folded = owned.try_fold_with(folder)?;
 803             *slot = ManuallyDrop::new(folded);
 804
 805             // Cast back to `Arc<T>`.
 806             Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
 807         }
 808     }
 809
 810     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 811         (**self).visit_with(visitor)
 812     }
 813 }
 814
 815 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 816     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 817         self,
 818         folder: &mut F,
 819     ) -> Result<Self, F::Error> {
 820         self.try_map_id(|value| value.try_fold_with(folder))
 821     }
 822
 823     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 824         (**self).visit_with(visitor)
 825     }
 826 }
 827
 828 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 829     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 830         self,
 831         folder: &mut F,
 832     ) -> Result<Self, F::Error> {
 833         self.try_map_id(|t| t.try_fold_with(folder))
 834     }
 835
 836     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 837         self.iter().try_for_each(|t| t.visit_with(visitor))
 838     }
 839 }
 840
 841 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 842     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 843         self,
 844         folder: &mut F,
 845     ) -> Result<Self, F::Error> {
 846         self.try_map_id(|t| t.try_fold_with(folder))
 847     }
 848
 849     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 850         self.iter().try_for_each(|t| t.visit_with(visitor))
 851     }
 852 }
 853
 854 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 855     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 856         self,
 857         folder: &mut F,
 858     ) -> Result<Self, F::Error> {
 859         self.try_map_bound(|ty| ty.try_fold_with(folder))
 860     }
 861
 862     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 863         folder.try_fold_binder(self)
 864     }
 865
 866     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 867         self.as_ref().skip_binder().visit_with(visitor)
 868     }
 869
 870     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 871         visitor.visit_binder(self)
 872     }
 873 }
 874
 875 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 876     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 877         self,
 878         folder: &mut F,
 879     ) -> Result<Self, F::Error> {
 880         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 881     }
 882
 883     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 884         self.iter().try_for_each(|p| p.visit_with(visitor))
 885     }
 886 }
 887
 888 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 889     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 890         self,
 891         folder: &mut F,
 892     ) -> Result<Self, F::Error> {
 893         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_type_list(v))
 894     }
 895
 896     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 897         self.iter().try_for_each(|t| t.visit_with(visitor))
 898     }
 899 }
 900
 901 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 902     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 903         self,
 904         folder: &mut F,
 905     ) -> Result<Self, F::Error> {
 906         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 907     }
 908
 909     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 910         self.iter().try_for_each(|t| t.visit_with(visitor))
 911     }
 912 }
 913
 914 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 915     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 916         self,
 917         folder: &mut F,
 918     ) -> Result<Self, F::Error> {
 919         use crate::ty::InstanceDef::*;
 920         Ok(Self {
 921             substs: self.substs.try_fold_with(folder)?,
 922             def: match self.def {
 923                 Item(def) => Item(def.try_fold_with(folder)?),
 924                 VtableShim(did) => VtableShim(did.try_fold_with(folder)?),
 925                 ReifyShim(did) => ReifyShim(did.try_fold_with(folder)?),
 926                 Intrinsic(did) => Intrinsic(did.try_fold_with(folder)?),
 927                 FnPtrShim(did, ty) => {
 928                     FnPtrShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 929                 }
 930                 Virtual(did, i) => Virtual(did.try_fold_with(folder)?, i),
 931                 ClosureOnceShim { call_once, track_caller } => {
 932                     ClosureOnceShim { call_once: call_once.try_fold_with(folder)?, track_caller }
 933                 }
 934                 DropGlue(did, ty) => {
 935                     DropGlue(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 936                 }
 937                 CloneShim(did, ty) => {
 938                     CloneShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 939                 }
 940             },
 941         })
 942     }
 943
 944     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 945         use crate::ty::InstanceDef::*;
 946         self.substs.visit_with(visitor)?;
 947         match self.def {
 948             Item(def) => def.visit_with(visitor),
 949             VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 950                 did.visit_with(visitor)
 951             }
 952             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 953                 did.visit_with(visitor)?;
 954                 ty.visit_with(visitor)
 955             }
 956             DropGlue(did, ty) => {
 957                 did.visit_with(visitor)?;
 958                 ty.visit_with(visitor)
 959             }
 960             ClosureOnceShim { call_once, track_caller: _ } => call_once.visit_with(visitor),
 961         }
 962     }
 963 }
 964
 965 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 966     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 967         self,
 968         folder: &mut F,
 969     ) -> Result<Self, F::Error> {
 970         Ok(Self { instance: self.instance.try_fold_with(folder)?, promoted: self.promoted })
 971     }
 972
 973     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 974         self.instance.visit_with(visitor)
 975     }
 976 }
 977
 978 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 979     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 980         self,
 981         folder: &mut F,
 982     ) -> Result<Self, F::Error> {
 983         let kind = match *self.kind() {
 984             ty::RawPtr(tm) => ty::RawPtr(tm.try_fold_with(folder)?),
 985             ty::Array(typ, sz) => ty::Array(typ.try_fold_with(folder)?, sz.try_fold_with(folder)?),
 986             ty::Slice(typ) => ty::Slice(typ.try_fold_with(folder)?),
 987             ty::Adt(tid, substs) => ty::Adt(tid, substs.try_fold_with(folder)?),
 988             ty::Dynamic(trait_ty, region) => {
 989                 ty::Dynamic(trait_ty.try_fold_with(folder)?, region.try_fold_with(folder)?)
 990             }
 991             ty::Tuple(ts) => ty::Tuple(ts.try_fold_with(folder)?),
 992             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.try_fold_with(folder)?),
 993             ty::FnPtr(f) => ty::FnPtr(f.try_fold_with(folder)?),
 994             ty::Ref(r, ty, mutbl) => {
 995                 ty::Ref(r.try_fold_with(folder)?, ty.try_fold_with(folder)?, mutbl)
 996             }
 997             ty::Generator(did, substs, movability) => {
 998                 ty::Generator(did, substs.try_fold_with(folder)?, movability)
 999             }
1000             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.try_fold_with(folder)?),
1001             ty::Closure(did, substs) => ty::Closure(did, substs.try_fold_with(folder)?),
1002             ty::Projection(data) => ty::Projection(data.try_fold_with(folder)?),
1003             ty::Opaque(did, substs) => ty::Opaque(did, substs.try_fold_with(folder)?),
1004
1005             ty::Bool
1006             | ty::Char
1007             | ty::Str
1008             | ty::Int(_)
1009             | ty::Uint(_)
1010             | ty::Float(_)
1011             | ty::Error(_)
1012             | ty::Infer(_)
1013             | ty::Param(..)
1014             | ty::Bound(..)
1015             | ty::Placeholder(..)
1016             | ty::Never
1017             | ty::Foreign(..) => return Ok(self),
1018         };
1019
1020         Ok(if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) })
1021     }
1022
1023     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1024         folder.try_fold_ty(self)
1025     }
1026
1027     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1028         match self.kind() {
1029             ty::RawPtr(ref tm) => tm.visit_with(visitor),
1030             ty::Array(typ, sz) => {
1031                 typ.visit_with(visitor)?;
1032                 sz.visit_with(visitor)
1033             }
1034             ty::Slice(typ) => typ.visit_with(visitor),
1035             ty::Adt(_, substs) => substs.visit_with(visitor),
1036             ty::Dynamic(ref trait_ty, ref reg) => {
1037                 trait_ty.visit_with(visitor)?;
1038                 reg.visit_with(visitor)
1039             }
1040             ty::Tuple(ts) => ts.visit_with(visitor),
1041             ty::FnDef(_, substs) => substs.visit_with(visitor),
1042             ty::FnPtr(ref f) => f.visit_with(visitor),
1043             ty::Ref(r, ty, _) => {
1044                 r.visit_with(visitor)?;
1045                 ty.visit_with(visitor)
1046             }
1047             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
1048             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
1049             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
1050             ty::Projection(ref data) => data.visit_with(visitor),
1051             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
1052
1053             ty::Bool
1054             | ty::Char
1055             | ty::Str
1056             | ty::Int(_)
1057             | ty::Uint(_)
1058             | ty::Float(_)
1059             | ty::Error(_)
1060             | ty::Infer(_)
1061             | ty::Bound(..)
1062             | ty::Placeholder(..)
1063             | ty::Param(..)
1064             | ty::Never
1065             | ty::Foreign(..) => ControlFlow::CONTINUE,
1066         }
1067     }
1068
1069     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1070         visitor.visit_ty(self)
1071     }
1072 }
1073
1074 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1075     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1076         self,
1077         _folder: &mut F,
1078     ) -> Result<Self, F::Error> {
1079         Ok(self)
1080     }
1081
1082     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1083         folder.try_fold_region(self)
1084     }
1085
1086     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1087         ControlFlow::CONTINUE
1088     }
1089
1090     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1091         visitor.visit_region(*self)
1092     }
1093 }
1094
1095 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1096     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1097         folder.try_fold_predicate(self)
1098     }
1099
1100     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1101         self,
1102         folder: &mut F,
1103     ) -> Result<Self, F::Error> {
1104         let new = self.inner.kind.try_fold_with(folder)?;
1105         Ok(folder.tcx().reuse_or_mk_predicate(self, new))
1106     }
1107
1108     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1109         self.inner.kind.visit_with(visitor)
1110     }
1111
1112     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1113         visitor.visit_predicate(*self)
1114     }
1115
1116     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1117         self.inner.outer_exclusive_binder > binder
1118     }
1119
1120     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1121         self.inner.flags.intersects(flags)
1122     }
1123 }
1124
1125 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1126     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1127         self,
1128         folder: &mut F,
1129     ) -> Result<Self, F::Error> {
1130         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
1131     }
1132
1133     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1134         self.iter().try_for_each(|p| p.visit_with(visitor))
1135     }
1136 }
1137
1138 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1139     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1140         self,
1141         folder: &mut F,
1142     ) -> Result<Self, F::Error> {
1143         self.try_map_id(|x| x.try_fold_with(folder))
1144     }
1145
1146     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1147         self.iter().try_for_each(|t| t.visit_with(visitor))
1148     }
1149 }
1150
1151 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1152     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1153         self,
1154         folder: &mut F,
1155     ) -> Result<Self, F::Error> {
1156         let ty = self.ty.try_fold_with(folder)?;
1157         let val = self.val.try_fold_with(folder)?;
1158         if ty != self.ty || val != self.val {
1159             Ok(folder.tcx().mk_const(ty::Const { ty, val }))
1160         } else {
1161             Ok(self)
1162         }
1163     }
1164
1165     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1166         folder.try_fold_const(self)
1167     }
1168
1169     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1170         self.ty.visit_with(visitor)?;
1171         self.val.visit_with(visitor)
1172     }
1173
1174     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1175         visitor.visit_const(self)
1176     }
1177 }
1178
1179 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1180     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1181         self,
1182         folder: &mut F,
1183     ) -> Result<Self, F::Error> {
1184         Ok(match self {
1185             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.try_fold_with(folder)?),
1186             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.try_fold_with(folder)?),
1187             ty::ConstKind::Unevaluated(uv) => ty::ConstKind::Unevaluated(uv.try_fold_with(folder)?),
1188             ty::ConstKind::Value(_)
1189             | ty::ConstKind::Bound(..)
1190             | ty::ConstKind::Placeholder(..)
1191             | ty::ConstKind::Error(_) => self,
1192         })
1193     }
1194
1195     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1196         match *self {
1197             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1198             ty::ConstKind::Param(p) => p.visit_with(visitor),
1199             ty::ConstKind::Unevaluated(uv) => uv.visit_with(visitor),
1200             ty::ConstKind::Value(_)
1201             | ty::ConstKind::Bound(..)
1202             | ty::ConstKind::Placeholder(_)
1203             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1204         }
1205     }
1206 }
1207
1208 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1209     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1210         self,
1211         _folder: &mut F,
1212     ) -> Result<Self, F::Error> {
1213         Ok(self)
1214     }
1215
1216     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1217         ControlFlow::CONTINUE
1218     }
1219 }
1220
1221 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
1222     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1223         self,
1224         folder: &mut F,
1225     ) -> Result<Self, F::Error> {
1226         Ok(ty::Unevaluated {
1227             def: self.def,
1228             substs: self.substs.try_fold_with(folder)?,
1229             promoted: self.promoted,
1230         })
1231     }
1232
1233     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1234         visitor.visit_unevaluated_const(*self)
1235     }
1236
1237     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1238         self.substs.visit_with(visitor)
1239     }
1240 }
1241
1242 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
1243     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1244         self,
1245         folder: &mut F,
1246     ) -> Result<Self, F::Error> {
1247         Ok(ty::Unevaluated {
1248             def: self.def,
1249             substs: self.substs.try_fold_with(folder)?,
1250             promoted: self.promoted,
1251         })
1252     }
1253
1254     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1255         visitor.visit_unevaluated_const(self.expand())
1256     }
1257
1258     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1259         self.substs.visit_with(visitor)
1260     }
1261 }