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, Term, 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.term)
 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 Term<'a> {
 360     type Lifted = ty::Term<'tcx>;
 361     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 362         Some(match self {
 363             Term::Ty(ty) => Term::Ty(tcx.lift(ty)?),
 364             Term::Const(c) => Term::Const(tcx.lift(c)?),
 365         })
 366     }
 367 }
 368
 369 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 370     type Lifted = ty::TraitPredicate<'tcx>;
 371     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 372         tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 373             trait_ref,
 374             constness: self.constness,
 375             polarity: self.polarity,
 376         })
 377     }
 378 }
 379
 380 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 381     type Lifted = ty::SubtypePredicate<'tcx>;
 382     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 383         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 384             a_is_expected: self.a_is_expected,
 385             a,
 386             b,
 387         })
 388     }
 389 }
 390
 391 impl<'a, 'tcx> Lift<'tcx> for ty::CoercePredicate<'a> {
 392     type Lifted = ty::CoercePredicate<'tcx>;
 393     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::CoercePredicate<'tcx>> {
 394         tcx.lift((self.a, self.b)).map(|(a, b)| ty::CoercePredicate { a, b })
 395     }
 396 }
 397
 398 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 399     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 400     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 401         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 402     }
 403 }
 404
 405 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 406     type Lifted = ty::ProjectionTy<'tcx>;
 407     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 408         tcx.lift(self.substs)
 409             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 410     }
 411 }
 412
 413 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 414     type Lifted = ty::ProjectionPredicate<'tcx>;
 415     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 416         tcx.lift((self.projection_ty, self.term))
 417             .map(|(projection_ty, term)| ty::ProjectionPredicate { projection_ty, term })
 418     }
 419 }
 420
 421 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 422     type Lifted = ty::ExistentialProjection<'tcx>;
 423     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 424         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 425             substs,
 426             term: tcx.lift(self.term).expect("type must lift when substs do"),
 427             item_def_id: self.item_def_id,
 428         })
 429     }
 430 }
 431
 432 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 433     type Lifted = ty::PredicateKind<'tcx>;
 434     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 435         match self {
 436             ty::PredicateKind::Trait(data) => tcx.lift(data).map(ty::PredicateKind::Trait),
 437             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 438             ty::PredicateKind::Coerce(data) => tcx.lift(data).map(ty::PredicateKind::Coerce),
 439             ty::PredicateKind::RegionOutlives(data) => {
 440                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 441             }
 442             ty::PredicateKind::TypeOutlives(data) => {
 443                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 444             }
 445             ty::PredicateKind::Projection(data) => {
 446                 tcx.lift(data).map(ty::PredicateKind::Projection)
 447             }
 448             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 449             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 450                 tcx.lift(closure_substs).map(|closure_substs| {
 451                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 452                 })
 453             }
 454             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 455                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 456             }
 457             ty::PredicateKind::ConstEvaluatable(uv) => {
 458                 tcx.lift(uv).map(|uv| ty::PredicateKind::ConstEvaluatable(uv))
 459             }
 460             ty::PredicateKind::ConstEquate(c1, c2) => {
 461                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 462             }
 463             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 464                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 465             }
 466         }
 467     }
 468 }
 469
 470 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 471 where
 472     <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>,
 473 {
 474     type Lifted = ty::Binder<'tcx, T::Lifted>;
 475     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 476         let bound_vars = tcx.lift(self.bound_vars());
 477         tcx.lift(self.skip_binder())
 478             .zip(bound_vars)
 479             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 480     }
 481 }
 482
 483 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 484     type Lifted = ty::ParamEnv<'tcx>;
 485     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 486         tcx.lift(self.caller_bounds())
 487             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.constness()))
 488     }
 489 }
 490
 491 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 492     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 493     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 494         tcx.lift(self.param_env).and_then(|param_env| {
 495             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 496         })
 497     }
 498 }
 499
 500 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 501     type Lifted = ty::ClosureSubsts<'tcx>;
 502     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 503         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 504     }
 505 }
 506
 507 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 508     type Lifted = ty::GeneratorSubsts<'tcx>;
 509     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 510         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 511     }
 512 }
 513
 514 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 515     type Lifted = ty::adjustment::Adjustment<'tcx>;
 516     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 517         let ty::adjustment::Adjustment { kind, target } = self;
 518         tcx.lift(kind).and_then(|kind| {
 519             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 520         })
 521     }
 522 }
 523
 524 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 525     type Lifted = ty::adjustment::Adjust<'tcx>;
 526     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 527         match self {
 528             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 529             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 530             ty::adjustment::Adjust::Deref(overloaded) => {
 531                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 532             }
 533             ty::adjustment::Adjust::Borrow(autoref) => {
 534                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 535             }
 536         }
 537     }
 538 }
 539
 540 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 541     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 542     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 543         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 544             region,
 545             mutbl: self.mutbl,
 546             span: self.span,
 547         })
 548     }
 549 }
 550
 551 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 552     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 553     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 554         match self {
 555             ty::adjustment::AutoBorrow::Ref(r, m) => {
 556                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 557             }
 558             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 559         }
 560     }
 561 }
 562
 563 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 564     type Lifted = ty::GenSig<'tcx>;
 565     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 566         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 567             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 568     }
 569 }
 570
 571 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 572     type Lifted = ty::FnSig<'tcx>;
 573     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 574         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 575             inputs_and_output: x,
 576             c_variadic: self.c_variadic,
 577             unsafety: self.unsafety,
 578             abi: self.abi,
 579         })
 580     }
 581 }
 582
 583 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 584     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 585     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 586         let ty::error::ExpectedFound { expected, found } = self;
 587         tcx.lift(expected).and_then(|expected| {
 588             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 589         })
 590     }
 591 }
 592
 593 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 594     type Lifted = ty::error::TypeError<'tcx>;
 595     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 596         use crate::ty::error::TypeError::*;
 597
 598         Some(match self {
 599             Mismatch => Mismatch,
 600             ConstnessMismatch(x) => ConstnessMismatch(x),
 601             PolarityMismatch(x) => PolarityMismatch(x),
 602             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 603             AbiMismatch(x) => AbiMismatch(x),
 604             Mutability => Mutability,
 605             ArgumentMutability(i) => ArgumentMutability(i),
 606             TupleSize(x) => TupleSize(x),
 607             FixedArraySize(x) => FixedArraySize(x),
 608             ArgCount => ArgCount,
 609             FieldMisMatch(x, y) => FieldMisMatch(x, y),
 610             RegionsDoesNotOutlive(a, b) => {
 611                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 612             }
 613             RegionsInsufficientlyPolymorphic(a, b) => {
 614                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 615             }
 616             RegionsOverlyPolymorphic(a, b) => {
 617                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 618             }
 619             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 620             IntMismatch(x) => IntMismatch(x),
 621             FloatMismatch(x) => FloatMismatch(x),
 622             Traits(x) => Traits(x),
 623             VariadicMismatch(x) => VariadicMismatch(x),
 624             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 625             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 626             ProjectionMismatched(x) => ProjectionMismatched(x),
 627             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 628             Sorts(x) => return tcx.lift(x).map(Sorts),
 629             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 630             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 631             IntrinsicCast => IntrinsicCast,
 632             TargetFeatureCast(x) => TargetFeatureCast(x),
 633             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 634         })
 635     }
 636 }
 637
 638 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 639     type Lifted = ty::InstanceDef<'tcx>;
 640     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 641         match self {
 642             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 643             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 644             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 645             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 646             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 647                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 648             }
 649             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 650             ty::InstanceDef::ClosureOnceShim { call_once, track_caller } => {
 651                 Some(ty::InstanceDef::ClosureOnceShim { call_once, track_caller })
 652             }
 653             ty::InstanceDef::DropGlue(def_id, ty) => {
 654                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 655             }
 656             ty::InstanceDef::CloneShim(def_id, ty) => {
 657                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 658             }
 659         }
 660     }
 661 }
 662
 663 ///////////////////////////////////////////////////////////////////////////
 664 // TypeFoldable implementations.
 665 //
 666 // Ideally, each type should invoke `folder.fold_foo(self)` and
 667 // nothing else. In some cases, though, we haven't gotten around to
 668 // adding methods on the `folder` yet, and thus the folding is
 669 // hard-coded here. This is less-flexible, because folders cannot
 670 // override the behavior, but there are a lot of random types and one
 671 // can easily refactor the folding into the TypeFolder trait as
 672 // needed.
 673
 674 /// AdtDefs are basically the same as a DefId.
 675 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 676     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 677         self,
 678         _folder: &mut F,
 679     ) -> Result<Self, F::Error> {
 680         Ok(self)
 681     }
 682
 683     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 684         ControlFlow::CONTINUE
 685     }
 686 }
 687
 688 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 689     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 690         self,
 691         folder: &mut F,
 692     ) -> Result<(T, U), F::Error> {
 693         Ok((self.0.try_fold_with(folder)?, self.1.try_fold_with(folder)?))
 694     }
 695
 696     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 697         self.0.visit_with(visitor)?;
 698         self.1.visit_with(visitor)
 699     }
 700 }
 701
 702 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 703     for (A, B, C)
 704 {
 705     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 706         self,
 707         folder: &mut F,
 708     ) -> Result<(A, B, C), F::Error> {
 709         Ok((
 710             self.0.try_fold_with(folder)?,
 711             self.1.try_fold_with(folder)?,
 712             self.2.try_fold_with(folder)?,
 713         ))
 714     }
 715
 716     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 717         self.0.visit_with(visitor)?;
 718         self.1.visit_with(visitor)?;
 719         self.2.visit_with(visitor)
 720     }
 721 }
 722
 723 EnumTypeFoldableImpl! {
 724     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 725         (Some)(a),
 726         (None),
 727     } where T: TypeFoldable<'tcx>
 728 }
 729
 730 EnumTypeFoldableImpl! {
 731     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 732         (Ok)(a),
 733         (Err)(a),
 734     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 735 }
 736
 737 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 738     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 739         mut self,
 740         folder: &mut F,
 741     ) -> Result<Self, F::Error> {
 742         // We merely want to replace the contained `T`, if at all possible,
 743         // so that we don't needlessly allocate a new `Rc` or indeed clone
 744         // the contained type.
 745         unsafe {
 746             // First step is to ensure that we have a unique reference to
 747             // the contained type, which `Rc::make_mut` will accomplish (by
 748             // allocating a new `Rc` and cloning the `T` only if required).
 749             // This is done *before* casting to `Rc<ManuallyDrop<T>>` so that
 750             // panicking during `make_mut` does not leak the `T`.
 751             Rc::make_mut(&mut self);
 752
 753             // Casting to `Rc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 754             // is `repr(transparent)`.
 755             let ptr = Rc::into_raw(self).cast::<ManuallyDrop<T>>();
 756             let mut unique = Rc::from_raw(ptr);
 757
 758             // Call to `Rc::make_mut` above guarantees that `unique` is the
 759             // sole reference to the contained value, so we can avoid doing
 760             // a checked `get_mut` here.
 761             let slot = Rc::get_mut_unchecked(&mut unique);
 762
 763             // Semantically move the contained type out from `unique`, fold
 764             // it, then move the folded value back into `unique`.  Should
 765             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 766             // value is not re-dropped.
 767             let owned = ManuallyDrop::take(slot);
 768             let folded = owned.try_fold_with(folder)?;
 769             *slot = ManuallyDrop::new(folded);
 770
 771             // Cast back to `Rc<T>`.
 772             Ok(Rc::from_raw(Rc::into_raw(unique).cast()))
 773         }
 774     }
 775
 776     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 777         (**self).visit_with(visitor)
 778     }
 779 }
 780
 781 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 782     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 783         mut self,
 784         folder: &mut F,
 785     ) -> Result<Self, F::Error> {
 786         // We merely want to replace the contained `T`, if at all possible,
 787         // so that we don't needlessly allocate a new `Arc` or indeed clone
 788         // the contained type.
 789         unsafe {
 790             // First step is to ensure that we have a unique reference to
 791             // the contained type, which `Arc::make_mut` will accomplish (by
 792             // allocating a new `Arc` and cloning the `T` only if required).
 793             // This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
 794             // panicking during `make_mut` does not leak the `T`.
 795             Arc::make_mut(&mut self);
 796
 797             // Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 798             // is `repr(transparent)`.
 799             let ptr = Arc::into_raw(self).cast::<ManuallyDrop<T>>();
 800             let mut unique = Arc::from_raw(ptr);
 801
 802             // Call to `Arc::make_mut` above guarantees that `unique` is the
 803             // sole reference to the contained value, so we can avoid doing
 804             // a checked `get_mut` here.
 805             let slot = Arc::get_mut_unchecked(&mut unique);
 806
 807             // Semantically move the contained type out from `unique`, fold
 808             // it, then move the folded value back into `unique`.  Should
 809             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 810             // value is not re-dropped.
 811             let owned = ManuallyDrop::take(slot);
 812             let folded = owned.try_fold_with(folder)?;
 813             *slot = ManuallyDrop::new(folded);
 814
 815             // Cast back to `Arc<T>`.
 816             Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
 817         }
 818     }
 819
 820     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 821         (**self).visit_with(visitor)
 822     }
 823 }
 824
 825 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 826     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 827         self,
 828         folder: &mut F,
 829     ) -> Result<Self, F::Error> {
 830         self.try_map_id(|value| value.try_fold_with(folder))
 831     }
 832
 833     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 834         (**self).visit_with(visitor)
 835     }
 836 }
 837
 838 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 839     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 840         self,
 841         folder: &mut F,
 842     ) -> Result<Self, F::Error> {
 843         self.try_map_id(|t| t.try_fold_with(folder))
 844     }
 845
 846     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 847         self.iter().try_for_each(|t| t.visit_with(visitor))
 848     }
 849 }
 850
 851 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 852     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 853         self,
 854         folder: &mut F,
 855     ) -> Result<Self, F::Error> {
 856         self.try_map_id(|t| t.try_fold_with(folder))
 857     }
 858
 859     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 860         self.iter().try_for_each(|t| t.visit_with(visitor))
 861     }
 862 }
 863
 864 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 865     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 866         self,
 867         folder: &mut F,
 868     ) -> Result<Self, F::Error> {
 869         self.try_map_bound(|ty| ty.try_fold_with(folder))
 870     }
 871
 872     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 873         folder.try_fold_binder(self)
 874     }
 875
 876     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 877         self.as_ref().skip_binder().visit_with(visitor)
 878     }
 879
 880     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 881         visitor.visit_binder(self)
 882     }
 883 }
 884
 885 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 886     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 887         self,
 888         folder: &mut F,
 889     ) -> Result<Self, F::Error> {
 890         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 891     }
 892
 893     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 894         self.iter().try_for_each(|p| p.visit_with(visitor))
 895     }
 896 }
 897
 898 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 899     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 900         self,
 901         folder: &mut F,
 902     ) -> Result<Self, F::Error> {
 903         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_type_list(v))
 904     }
 905
 906     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 907         self.iter().try_for_each(|t| t.visit_with(visitor))
 908     }
 909 }
 910
 911 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 912     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 913         self,
 914         folder: &mut F,
 915     ) -> Result<Self, F::Error> {
 916         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 917     }
 918
 919     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 920         self.iter().try_for_each(|t| t.visit_with(visitor))
 921     }
 922 }
 923
 924 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 925     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 926         self,
 927         folder: &mut F,
 928     ) -> Result<Self, F::Error> {
 929         use crate::ty::InstanceDef::*;
 930         Ok(Self {
 931             substs: self.substs.try_fold_with(folder)?,
 932             def: match self.def {
 933                 Item(def) => Item(def.try_fold_with(folder)?),
 934                 VtableShim(did) => VtableShim(did.try_fold_with(folder)?),
 935                 ReifyShim(did) => ReifyShim(did.try_fold_with(folder)?),
 936                 Intrinsic(did) => Intrinsic(did.try_fold_with(folder)?),
 937                 FnPtrShim(did, ty) => {
 938                     FnPtrShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 939                 }
 940                 Virtual(did, i) => Virtual(did.try_fold_with(folder)?, i),
 941                 ClosureOnceShim { call_once, track_caller } => {
 942                     ClosureOnceShim { call_once: call_once.try_fold_with(folder)?, track_caller }
 943                 }
 944                 DropGlue(did, ty) => {
 945                     DropGlue(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 946                 }
 947                 CloneShim(did, ty) => {
 948                     CloneShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 949                 }
 950             },
 951         })
 952     }
 953
 954     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 955         use crate::ty::InstanceDef::*;
 956         self.substs.visit_with(visitor)?;
 957         match self.def {
 958             Item(def) => def.visit_with(visitor),
 959             VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 960                 did.visit_with(visitor)
 961             }
 962             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 963                 did.visit_with(visitor)?;
 964                 ty.visit_with(visitor)
 965             }
 966             DropGlue(did, ty) => {
 967                 did.visit_with(visitor)?;
 968                 ty.visit_with(visitor)
 969             }
 970             ClosureOnceShim { call_once, track_caller: _ } => call_once.visit_with(visitor),
 971         }
 972     }
 973 }
 974
 975 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 976     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 977         self,
 978         folder: &mut F,
 979     ) -> Result<Self, F::Error> {
 980         Ok(Self { instance: self.instance.try_fold_with(folder)?, promoted: self.promoted })
 981     }
 982
 983     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 984         self.instance.visit_with(visitor)
 985     }
 986 }
 987
 988 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 989     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 990         self,
 991         folder: &mut F,
 992     ) -> Result<Self, F::Error> {
 993         let kind = match *self.kind() {
 994             ty::RawPtr(tm) => ty::RawPtr(tm.try_fold_with(folder)?),
 995             ty::Array(typ, sz) => ty::Array(typ.try_fold_with(folder)?, sz.try_fold_with(folder)?),
 996             ty::Slice(typ) => ty::Slice(typ.try_fold_with(folder)?),
 997             ty::Adt(tid, substs) => ty::Adt(tid, substs.try_fold_with(folder)?),
 998             ty::Dynamic(trait_ty, region) => {
 999                 ty::Dynamic(trait_ty.try_fold_with(folder)?, region.try_fold_with(folder)?)
1000             }
1001             ty::Tuple(ts) => ty::Tuple(ts.try_fold_with(folder)?),
1002             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.try_fold_with(folder)?),
1003             ty::FnPtr(f) => ty::FnPtr(f.try_fold_with(folder)?),
1004             ty::Ref(r, ty, mutbl) => {
1005                 ty::Ref(r.try_fold_with(folder)?, ty.try_fold_with(folder)?, mutbl)
1006             }
1007             ty::Generator(did, substs, movability) => {
1008                 ty::Generator(did, substs.try_fold_with(folder)?, movability)
1009             }
1010             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.try_fold_with(folder)?),
1011             ty::Closure(did, substs) => ty::Closure(did, substs.try_fold_with(folder)?),
1012             ty::Projection(data) => ty::Projection(data.try_fold_with(folder)?),
1013             ty::Opaque(did, substs) => ty::Opaque(did, substs.try_fold_with(folder)?),
1014
1015             ty::Bool
1016             | ty::Char
1017             | ty::Str
1018             | ty::Int(_)
1019             | ty::Uint(_)
1020             | ty::Float(_)
1021             | ty::Error(_)
1022             | ty::Infer(_)
1023             | ty::Param(..)
1024             | ty::Bound(..)
1025             | ty::Placeholder(..)
1026             | ty::Never
1027             | ty::Foreign(..) => return Ok(self),
1028         };
1029
1030         Ok(if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) })
1031     }
1032
1033     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1034         folder.try_fold_ty(self)
1035     }
1036
1037     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1038         match self.kind() {
1039             ty::RawPtr(ref tm) => tm.visit_with(visitor),
1040             ty::Array(typ, sz) => {
1041                 typ.visit_with(visitor)?;
1042                 sz.visit_with(visitor)
1043             }
1044             ty::Slice(typ) => typ.visit_with(visitor),
1045             ty::Adt(_, substs) => substs.visit_with(visitor),
1046             ty::Dynamic(ref trait_ty, ref reg) => {
1047                 trait_ty.visit_with(visitor)?;
1048                 reg.visit_with(visitor)
1049             }
1050             ty::Tuple(ts) => ts.visit_with(visitor),
1051             ty::FnDef(_, substs) => substs.visit_with(visitor),
1052             ty::FnPtr(ref f) => f.visit_with(visitor),
1053             ty::Ref(r, ty, _) => {
1054                 r.visit_with(visitor)?;
1055                 ty.visit_with(visitor)
1056             }
1057             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
1058             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
1059             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
1060             ty::Projection(ref data) => data.visit_with(visitor),
1061             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
1062
1063             ty::Bool
1064             | ty::Char
1065             | ty::Str
1066             | ty::Int(_)
1067             | ty::Uint(_)
1068             | ty::Float(_)
1069             | ty::Error(_)
1070             | ty::Infer(_)
1071             | ty::Bound(..)
1072             | ty::Placeholder(..)
1073             | ty::Param(..)
1074             | ty::Never
1075             | ty::Foreign(..) => ControlFlow::CONTINUE,
1076         }
1077     }
1078
1079     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1080         visitor.visit_ty(self)
1081     }
1082 }
1083
1084 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1085     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1086         self,
1087         _folder: &mut F,
1088     ) -> Result<Self, F::Error> {
1089         Ok(self)
1090     }
1091
1092     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1093         folder.try_fold_region(self)
1094     }
1095
1096     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1097         ControlFlow::CONTINUE
1098     }
1099
1100     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1101         visitor.visit_region(*self)
1102     }
1103 }
1104
1105 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1106     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1107         folder.try_fold_predicate(self)
1108     }
1109
1110     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1111         self,
1112         folder: &mut F,
1113     ) -> Result<Self, F::Error> {
1114         let new = self.inner.kind.try_fold_with(folder)?;
1115         Ok(folder.tcx().reuse_or_mk_predicate(self, new))
1116     }
1117
1118     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1119         self.inner.kind.visit_with(visitor)
1120     }
1121
1122     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1123         visitor.visit_predicate(*self)
1124     }
1125
1126     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1127         self.inner.outer_exclusive_binder > binder
1128     }
1129
1130     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1131         self.inner.flags.intersects(flags)
1132     }
1133 }
1134
1135 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1136     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1137         self,
1138         folder: &mut F,
1139     ) -> Result<Self, F::Error> {
1140         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
1141     }
1142
1143     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1144         self.iter().try_for_each(|p| p.visit_with(visitor))
1145     }
1146 }
1147
1148 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1149     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1150         self,
1151         folder: &mut F,
1152     ) -> Result<Self, F::Error> {
1153         self.try_map_id(|x| x.try_fold_with(folder))
1154     }
1155
1156     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1157         self.iter().try_for_each(|t| t.visit_with(visitor))
1158     }
1159 }
1160
1161 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1162     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1163         self,
1164         folder: &mut F,
1165     ) -> Result<Self, F::Error> {
1166         let ty = self.ty.try_fold_with(folder)?;
1167         let val = self.val.try_fold_with(folder)?;
1168         if ty != self.ty || val != self.val {
1169             Ok(folder.tcx().mk_const(ty::Const { ty, val }))
1170         } else {
1171             Ok(self)
1172         }
1173     }
1174
1175     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1176         folder.try_fold_const(self)
1177     }
1178
1179     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1180         self.ty.visit_with(visitor)?;
1181         self.val.visit_with(visitor)
1182     }
1183
1184     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1185         visitor.visit_const(self)
1186     }
1187 }
1188
1189 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1190     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1191         self,
1192         folder: &mut F,
1193     ) -> Result<Self, F::Error> {
1194         Ok(match self {
1195             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.try_fold_with(folder)?),
1196             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.try_fold_with(folder)?),
1197             ty::ConstKind::Unevaluated(uv) => ty::ConstKind::Unevaluated(uv.try_fold_with(folder)?),
1198             ty::ConstKind::Value(_)
1199             | ty::ConstKind::Bound(..)
1200             | ty::ConstKind::Placeholder(..)
1201             | ty::ConstKind::Error(_) => self,
1202         })
1203     }
1204
1205     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1206         match *self {
1207             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1208             ty::ConstKind::Param(p) => p.visit_with(visitor),
1209             ty::ConstKind::Unevaluated(uv) => uv.visit_with(visitor),
1210             ty::ConstKind::Value(_)
1211             | ty::ConstKind::Bound(..)
1212             | ty::ConstKind::Placeholder(_)
1213             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1214         }
1215     }
1216 }
1217
1218 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1219     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1220         self,
1221         _folder: &mut F,
1222     ) -> Result<Self, F::Error> {
1223         Ok(self)
1224     }
1225
1226     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1227         ControlFlow::CONTINUE
1228     }
1229 }
1230
1231 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
1232     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1233         self,
1234         folder: &mut F,
1235     ) -> Result<Self, F::Error> {
1236         Ok(ty::Unevaluated {
1237             def: self.def,
1238             substs: self.substs.try_fold_with(folder)?,
1239             promoted: self.promoted,
1240         })
1241     }
1242
1243     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1244         visitor.visit_unevaluated_const(*self)
1245     }
1246
1247     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1248         self.substs.visit_with(visitor)
1249     }
1250 }
1251
1252 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
1253     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1254         self,
1255         folder: &mut F,
1256     ) -> Result<Self, F::Error> {
1257         Ok(ty::Unevaluated {
1258             def: self.def,
1259             substs: self.substs.try_fold_with(folder)?,
1260             promoted: self.promoted,
1261         })
1262     }
1263
1264     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1265         visitor.visit_unevaluated_const(self.expand())
1266     }
1267
1268     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1269         self.substs.visit_with(visitor)
1270     }
1271 }