compiler/rustc_middle/src/ty/structural_impls.rs

   1 //! This module contains implements of the `Lift` and `TypeFoldable`
   2 //! traits for various types in the Rust compiler. Most are written by
   3 //! hand, though we've recently added some macros and proc-macros to help with the tedium.
   4
   5 use crate::mir::interpret;
   6 use crate::mir::ProjectionKind;
   7 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
   8 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
   9 use crate::ty::{self, InferConst, Lift, Ty, TyCtxt};
  10 use rustc_data_structures::functor::IdFunctor;
  11 use rustc_hir::def::Namespace;
  12 use rustc_hir::def_id::CRATE_DEF_INDEX;
  13 use rustc_index::vec::{Idx, IndexVec};
  14
  15 use std::fmt;
  16 use std::ops::ControlFlow;
  17 use std::rc::Rc;
  18 use std::sync::Arc;
  19
  20 impl fmt::Debug for ty::TraitDef {
  21     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  22         ty::tls::with(|tcx| {
  23             with_no_trimmed_paths(|| {
  24                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.def_id, &[])
  25             })?;
  26             Ok(())
  27         })
  28     }
  29 }
  30
  31 impl fmt::Debug for ty::AdtDef {
  32     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  33         ty::tls::with(|tcx| {
  34             with_no_trimmed_paths(|| {
  35                 FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.did, &[])
  36             })?;
  37             Ok(())
  38         })
  39     }
  40 }
  41
  42 impl fmt::Debug for ty::UpvarId {
  43     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  44         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  45         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  46     }
  47 }
  48
  49 impl fmt::Debug for ty::UpvarBorrow<'tcx> {
  50     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  51         write!(f, "UpvarBorrow({:?}, {:?})", self.kind, self.region)
  52     }
  53 }
  54
  55 impl fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  56     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  57         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
  58     }
  59 }
  60
  61 impl fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  62     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  63         write!(f, "{:?} -> {}", self.kind, self.target)
  64     }
  65 }
  66
  67 impl fmt::Debug for ty::BoundRegionKind {
  68     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  69         match *self {
  70             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  71             ty::BrNamed(did, name) => {
  72                 if did.index == CRATE_DEF_INDEX {
  73                     write!(f, "BrNamed({})", name)
  74                 } else {
  75                     write!(f, "BrNamed({:?}, {})", did, name)
  76                 }
  77             }
  78             ty::BrEnv => write!(f, "BrEnv"),
  79         }
  80     }
  81 }
  82
  83 impl fmt::Debug for ty::RegionKind {
  84     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  85         match *self {
  86             ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name),
  87
  88             ty::ReLateBound(binder_id, ref bound_region) => {
  89                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
  90             }
  91
  92             ty::ReFree(ref fr) => fr.fmt(f),
  93
  94             ty::ReStatic => write!(f, "ReStatic"),
  95
  96             ty::ReVar(ref vid) => vid.fmt(f),
  97
  98             ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder),
  99
 100             ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui),
 101
 102             ty::ReErased => write!(f, "ReErased"),
 103         }
 104     }
 105 }
 106
 107 impl fmt::Debug for ty::FreeRegion {
 108     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 109         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 110     }
 111 }
 112
 113 impl fmt::Debug for ty::FnSig<'tcx> {
 114     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 115         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 116     }
 117 }
 118
 119 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 120     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 121         write!(f, "_#{}c", self.index)
 122     }
 123 }
 124
 125 impl fmt::Debug for ty::RegionVid {
 126     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 127         write!(f, "'_#{}r", self.index())
 128     }
 129 }
 130
 131 impl fmt::Debug for ty::TraitRef<'tcx> {
 132     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 133         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 134     }
 135 }
 136
 137 impl fmt::Debug for Ty<'tcx> {
 138     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 139         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 140     }
 141 }
 142
 143 impl fmt::Debug for ty::ParamTy {
 144     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 145         write!(f, "{}/#{}", self.name, self.index)
 146     }
 147 }
 148
 149 impl fmt::Debug for ty::ParamConst {
 150     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 151         write!(f, "{}/#{}", self.name, self.index)
 152     }
 153 }
 154
 155 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 156     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 157         if let ty::BoundConstness::ConstIfConst = self.constness {
 158             write!(f, "~const ")?;
 159         }
 160         write!(f, "TraitPredicate({:?})", self.trait_ref)
 161     }
 162 }
 163
 164 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 165     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 166         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 167     }
 168 }
 169
 170 impl fmt::Debug for ty::Predicate<'tcx> {
 171     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 172         write!(f, "{:?}", self.kind())
 173     }
 174 }
 175
 176 impl fmt::Debug for ty::PredicateKind<'tcx> {
 177     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 178         match *self {
 179             ty::PredicateKind::Trait(ref a) => a.fmt(f),
 180             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 181             ty::PredicateKind::Coerce(ref pair) => pair.fmt(f),
 182             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 183             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 184             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 185             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 186             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 187                 write!(f, "ObjectSafe({:?})", trait_def_id)
 188             }
 189             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 190                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 191             }
 192             ty::PredicateKind::ConstEvaluatable(uv) => {
 193                 write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs_)
 194             }
 195             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 196             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 197                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 198             }
 199         }
 200     }
 201 }
 202
 203 ///////////////////////////////////////////////////////////////////////////
 204 // Atomic structs
 205 //
 206 // For things that don't carry any arena-allocated data (and are
 207 // copy...), just add them to this list.
 208
 209 TrivialTypeFoldableAndLiftImpls! {
 210     (),
 211     bool,
 212     usize,
 213     ::rustc_target::abi::VariantIdx,
 214     u32,
 215     u64,
 216     String,
 217     crate::middle::region::Scope,
 218     crate::ty::FloatTy,
 219     ::rustc_ast::InlineAsmOptions,
 220     ::rustc_ast::InlineAsmTemplatePiece,
 221     ::rustc_ast::NodeId,
 222     ::rustc_span::symbol::Symbol,
 223     ::rustc_hir::def::Res,
 224     ::rustc_hir::def_id::DefId,
 225     ::rustc_hir::def_id::LocalDefId,
 226     ::rustc_hir::HirId,
 227     ::rustc_hir::LlvmInlineAsmInner,
 228     ::rustc_hir::MatchSource,
 229     ::rustc_hir::Mutability,
 230     ::rustc_hir::Unsafety,
 231     ::rustc_target::asm::InlineAsmRegOrRegClass,
 232     ::rustc_target::spec::abi::Abi,
 233     crate::mir::coverage::ExpressionOperandId,
 234     crate::mir::coverage::CounterValueReference,
 235     crate::mir::coverage::InjectedExpressionId,
 236     crate::mir::coverage::InjectedExpressionIndex,
 237     crate::mir::coverage::MappedExpressionIndex,
 238     crate::mir::Local,
 239     crate::mir::Promoted,
 240     crate::traits::Reveal,
 241     crate::ty::adjustment::AutoBorrowMutability,
 242     crate::ty::AdtKind,
 243     crate::ty::BoundConstness,
 244     // Including `BoundRegionKind` is a *bit* dubious, but direct
 245     // references to bound region appear in `ty::Error`, and aren't
 246     // really meant to be folded. In general, we can only fold a fully
 247     // general `Region`.
 248     crate::ty::BoundRegionKind,
 249     crate::ty::AssocItem,
 250     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 251     crate::ty::ClosureKind,
 252     crate::ty::FreeRegion,
 253     crate::ty::InferTy,
 254     crate::ty::IntVarValue,
 255     crate::ty::ParamConst,
 256     crate::ty::ParamTy,
 257     crate::ty::adjustment::PointerCast,
 258     crate::ty::RegionVid,
 259     crate::ty::UniverseIndex,
 260     crate::ty::Variance,
 261     ::rustc_span::Span,
 262 }
 263
 264 ///////////////////////////////////////////////////////////////////////////
 265 // Lift implementations
 266
 267 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 268 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 269     type Lifted = (A::Lifted, B::Lifted);
 270     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 271         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 272     }
 273 }
 274
 275 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 276     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 277     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 278         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 279     }
 280 }
 281
 282 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 283     type Lifted = Option<T::Lifted>;
 284     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 285         match self {
 286             Some(x) => tcx.lift(x).map(Some),
 287             None => Some(None),
 288         }
 289     }
 290 }
 291
 292 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 293     type Lifted = Result<T::Lifted, E::Lifted>;
 294     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 295         match self {
 296             Ok(x) => tcx.lift(x).map(Ok),
 297             Err(e) => tcx.lift(e).map(Err),
 298         }
 299     }
 300 }
 301
 302 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 303     type Lifted = Box<T::Lifted>;
 304     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 305         tcx.lift(*self).map(Box::new)
 306     }
 307 }
 308
 309 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 310     type Lifted = Rc<T::Lifted>;
 311     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 312         tcx.lift(self.as_ref().clone()).map(Rc::new)
 313     }
 314 }
 315
 316 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 317     type Lifted = Arc<T::Lifted>;
 318     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 319         tcx.lift(self.as_ref().clone()).map(Arc::new)
 320     }
 321 }
 322 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 323     type Lifted = Vec<T::Lifted>;
 324     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 325         self.into_iter().map(|v| tcx.lift(v)).collect()
 326     }
 327 }
 328
 329 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 330     type Lifted = IndexVec<I, T::Lifted>;
 331     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 332         self.into_iter().map(|e| tcx.lift(e)).collect()
 333     }
 334 }
 335
 336 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 337     type Lifted = ty::TraitRef<'tcx>;
 338     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 339         tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 340     }
 341 }
 342
 343 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 344     type Lifted = ty::ExistentialTraitRef<'tcx>;
 345     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 346         tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 347     }
 348 }
 349
 350 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 351     type Lifted = ty::ExistentialPredicate<'tcx>;
 352     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 353         match self {
 354             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 355             ty::ExistentialPredicate::Projection(x) => {
 356                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 357             }
 358             ty::ExistentialPredicate::AutoTrait(def_id) => {
 359                 Some(ty::ExistentialPredicate::AutoTrait(def_id))
 360             }
 361         }
 362     }
 363 }
 364
 365 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 366     type Lifted = ty::TraitPredicate<'tcx>;
 367     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 368         tcx.lift(self.trait_ref)
 369             .map(|trait_ref| ty::TraitPredicate { trait_ref, constness: self.constness })
 370     }
 371 }
 372
 373 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 374     type Lifted = ty::SubtypePredicate<'tcx>;
 375     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 376         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 377             a_is_expected: self.a_is_expected,
 378             a,
 379             b,
 380         })
 381     }
 382 }
 383
 384 impl<'a, 'tcx> Lift<'tcx> for ty::CoercePredicate<'a> {
 385     type Lifted = ty::CoercePredicate<'tcx>;
 386     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::CoercePredicate<'tcx>> {
 387         tcx.lift((self.a, self.b)).map(|(a, b)| ty::CoercePredicate { a, b })
 388     }
 389 }
 390
 391 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 392     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 393     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 394         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 395     }
 396 }
 397
 398 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 399     type Lifted = ty::ProjectionTy<'tcx>;
 400     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 401         tcx.lift(self.substs)
 402             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 403     }
 404 }
 405
 406 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 407     type Lifted = ty::ProjectionPredicate<'tcx>;
 408     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 409         tcx.lift((self.projection_ty, self.ty))
 410             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 411     }
 412 }
 413
 414 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 415     type Lifted = ty::ExistentialProjection<'tcx>;
 416     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 417         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 418             substs,
 419             ty: tcx.lift(self.ty).expect("type must lift when substs do"),
 420             item_def_id: self.item_def_id,
 421         })
 422     }
 423 }
 424
 425 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 426     type Lifted = ty::PredicateKind<'tcx>;
 427     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 428         match self {
 429             ty::PredicateKind::Trait(data) => tcx.lift(data).map(ty::PredicateKind::Trait),
 430             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 431             ty::PredicateKind::Coerce(data) => tcx.lift(data).map(ty::PredicateKind::Coerce),
 432             ty::PredicateKind::RegionOutlives(data) => {
 433                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 434             }
 435             ty::PredicateKind::TypeOutlives(data) => {
 436                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 437             }
 438             ty::PredicateKind::Projection(data) => {
 439                 tcx.lift(data).map(ty::PredicateKind::Projection)
 440             }
 441             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 442             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 443                 tcx.lift(closure_substs).map(|closure_substs| {
 444                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 445                 })
 446             }
 447             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 448                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 449             }
 450             ty::PredicateKind::ConstEvaluatable(uv) => {
 451                 tcx.lift(uv).map(|uv| ty::PredicateKind::ConstEvaluatable(uv))
 452             }
 453             ty::PredicateKind::ConstEquate(c1, c2) => {
 454                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 455             }
 456             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 457                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 458             }
 459         }
 460     }
 461 }
 462
 463 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 464 where
 465     <T as Lift<'tcx>>::Lifted: TypeFoldable<'tcx>,
 466 {
 467     type Lifted = ty::Binder<'tcx, T::Lifted>;
 468     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 469         let bound_vars = tcx.lift(self.bound_vars());
 470         tcx.lift(self.skip_binder())
 471             .zip(bound_vars)
 472             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 473     }
 474 }
 475
 476 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 477     type Lifted = ty::ParamEnv<'tcx>;
 478     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 479         tcx.lift(self.caller_bounds())
 480             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
 481     }
 482 }
 483
 484 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 485     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 486     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 487         tcx.lift(self.param_env).and_then(|param_env| {
 488             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 489         })
 490     }
 491 }
 492
 493 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 494     type Lifted = ty::ClosureSubsts<'tcx>;
 495     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 496         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 497     }
 498 }
 499
 500 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 501     type Lifted = ty::GeneratorSubsts<'tcx>;
 502     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 503         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 504     }
 505 }
 506
 507 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 508     type Lifted = ty::adjustment::Adjustment<'tcx>;
 509     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 510         let ty::adjustment::Adjustment { kind, target } = self;
 511         tcx.lift(kind).and_then(|kind| {
 512             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 513         })
 514     }
 515 }
 516
 517 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 518     type Lifted = ty::adjustment::Adjust<'tcx>;
 519     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 520         match self {
 521             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 522             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 523             ty::adjustment::Adjust::Deref(overloaded) => {
 524                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 525             }
 526             ty::adjustment::Adjust::Borrow(autoref) => {
 527                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 528             }
 529         }
 530     }
 531 }
 532
 533 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 534     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 535     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 536         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 537             region,
 538             mutbl: self.mutbl,
 539             span: self.span,
 540         })
 541     }
 542 }
 543
 544 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 545     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 546     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 547         match self {
 548             ty::adjustment::AutoBorrow::Ref(r, m) => {
 549                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 550             }
 551             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 552         }
 553     }
 554 }
 555
 556 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 557     type Lifted = ty::GenSig<'tcx>;
 558     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 559         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 560             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 561     }
 562 }
 563
 564 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 565     type Lifted = ty::FnSig<'tcx>;
 566     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 567         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 568             inputs_and_output: x,
 569             c_variadic: self.c_variadic,
 570             unsafety: self.unsafety,
 571             abi: self.abi,
 572         })
 573     }
 574 }
 575
 576 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 577     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 578     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 579         let ty::error::ExpectedFound { expected, found } = self;
 580         tcx.lift(expected).and_then(|expected| {
 581             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 582         })
 583     }
 584 }
 585
 586 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 587     type Lifted = ty::error::TypeError<'tcx>;
 588     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 589         use crate::ty::error::TypeError::*;
 590
 591         Some(match self {
 592             Mismatch => Mismatch,
 593             ConstnessMismatch(x) => ConstnessMismatch(x),
 594             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 595             AbiMismatch(x) => AbiMismatch(x),
 596             Mutability => Mutability,
 597             ArgumentMutability(i) => ArgumentMutability(i),
 598             TupleSize(x) => TupleSize(x),
 599             FixedArraySize(x) => FixedArraySize(x),
 600             ArgCount => ArgCount,
 601             RegionsDoesNotOutlive(a, b) => {
 602                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 603             }
 604             RegionsInsufficientlyPolymorphic(a, b) => {
 605                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 606             }
 607             RegionsOverlyPolymorphic(a, b) => {
 608                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 609             }
 610             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 611             IntMismatch(x) => IntMismatch(x),
 612             FloatMismatch(x) => FloatMismatch(x),
 613             Traits(x) => Traits(x),
 614             VariadicMismatch(x) => VariadicMismatch(x),
 615             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 616             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 617             ProjectionMismatched(x) => ProjectionMismatched(x),
 618             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 619             Sorts(x) => return tcx.lift(x).map(Sorts),
 620             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 621             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 622             IntrinsicCast => IntrinsicCast,
 623             TargetFeatureCast(x) => TargetFeatureCast(x),
 624             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 625         })
 626     }
 627 }
 628
 629 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 630     type Lifted = ty::InstanceDef<'tcx>;
 631     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 632         match self {
 633             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 634             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 635             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 636             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 637             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 638                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 639             }
 640             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 641             ty::InstanceDef::ClosureOnceShim { call_once, track_caller } => {
 642                 Some(ty::InstanceDef::ClosureOnceShim { call_once, track_caller })
 643             }
 644             ty::InstanceDef::DropGlue(def_id, ty) => {
 645                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 646             }
 647             ty::InstanceDef::CloneShim(def_id, ty) => {
 648                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 649             }
 650         }
 651     }
 652 }
 653
 654 ///////////////////////////////////////////////////////////////////////////
 655 // TypeFoldable implementations.
 656 //
 657 // Ideally, each type should invoke `folder.fold_foo(self)` and
 658 // nothing else. In some cases, though, we haven't gotten around to
 659 // adding methods on the `folder` yet, and thus the folding is
 660 // hard-coded here. This is less-flexible, because folders cannot
 661 // override the behavior, but there are a lot of random types and one
 662 // can easily refactor the folding into the TypeFolder trait as
 663 // needed.
 664
 665 /// AdtDefs are basically the same as a DefId.
 666 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 667     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 668         self
 669     }
 670
 671     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 672         ControlFlow::CONTINUE
 673     }
 674 }
 675
 676 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 677     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (T, U) {
 678         (self.0.fold_with(folder), self.1.fold_with(folder))
 679     }
 680
 681     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 682         self.0.visit_with(visitor)?;
 683         self.1.visit_with(visitor)
 684     }
 685 }
 686
 687 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 688     for (A, B, C)
 689 {
 690     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> (A, B, C) {
 691         (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
 692     }
 693
 694     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 695         self.0.visit_with(visitor)?;
 696         self.1.visit_with(visitor)?;
 697         self.2.visit_with(visitor)
 698     }
 699 }
 700
 701 EnumTypeFoldableImpl! {
 702     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 703         (Some)(a),
 704         (None),
 705     } where T: TypeFoldable<'tcx>
 706 }
 707
 708 EnumTypeFoldableImpl! {
 709     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 710         (Ok)(a),
 711         (Err)(a),
 712     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 713 }
 714
 715 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 716     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 717         // FIXME: Reuse the `Rc` here.
 718         Rc::new((*self).clone().fold_with(folder))
 719     }
 720
 721     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 722         (**self).visit_with(visitor)
 723     }
 724 }
 725
 726 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 727     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 728         // FIXME: Reuse the `Arc` here.
 729         Arc::new((*self).clone().fold_with(folder))
 730     }
 731
 732     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 733         (**self).visit_with(visitor)
 734     }
 735 }
 736
 737 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 738     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 739         self.map_id(|value| value.fold_with(folder))
 740     }
 741
 742     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 743         (**self).visit_with(visitor)
 744     }
 745 }
 746
 747 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 748     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 749         self.map_id(|t| t.fold_with(folder))
 750     }
 751
 752     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 753         self.iter().try_for_each(|t| t.visit_with(visitor))
 754     }
 755 }
 756
 757 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 758     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 759         self.map_id(|t| t.fold_with(folder))
 760     }
 761
 762     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 763         self.iter().try_for_each(|t| t.visit_with(visitor))
 764     }
 765 }
 766
 767 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 768     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 769         self.map_bound(|ty| ty.fold_with(folder))
 770     }
 771
 772     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 773         folder.fold_binder(self)
 774     }
 775
 776     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 777         self.as_ref().skip_binder().visit_with(visitor)
 778     }
 779
 780     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 781         visitor.visit_binder(self)
 782     }
 783 }
 784
 785 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 786     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 787         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 788     }
 789
 790     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 791         self.iter().try_for_each(|p| p.visit_with(visitor))
 792     }
 793 }
 794
 795 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 796     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 797         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_type_list(v))
 798     }
 799
 800     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 801         self.iter().try_for_each(|t| t.visit_with(visitor))
 802     }
 803 }
 804
 805 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 806     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 807         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 808     }
 809
 810     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 811         self.iter().try_for_each(|t| t.visit_with(visitor))
 812     }
 813 }
 814
 815 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 816     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 817         use crate::ty::InstanceDef::*;
 818         Self {
 819             substs: self.substs.fold_with(folder),
 820             def: match self.def {
 821                 Item(def) => Item(def.fold_with(folder)),
 822                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 823                 ReifyShim(did) => ReifyShim(did.fold_with(folder)),
 824                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 825                 FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)),
 826                 Virtual(did, i) => Virtual(did.fold_with(folder), i),
 827                 ClosureOnceShim { call_once, track_caller } => {
 828                     ClosureOnceShim { call_once: call_once.fold_with(folder), track_caller }
 829                 }
 830                 DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)),
 831                 CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)),
 832             },
 833         }
 834     }
 835
 836     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 837         use crate::ty::InstanceDef::*;
 838         self.substs.visit_with(visitor)?;
 839         match self.def {
 840             Item(def) => def.visit_with(visitor),
 841             VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 842                 did.visit_with(visitor)
 843             }
 844             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 845                 did.visit_with(visitor)?;
 846                 ty.visit_with(visitor)
 847             }
 848             DropGlue(did, ty) => {
 849                 did.visit_with(visitor)?;
 850                 ty.visit_with(visitor)
 851             }
 852             ClosureOnceShim { call_once, track_caller: _ } => call_once.visit_with(visitor),
 853         }
 854     }
 855 }
 856
 857 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 858     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 859         Self { instance: self.instance.fold_with(folder), promoted: self.promoted }
 860     }
 861
 862     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 863         self.instance.visit_with(visitor)
 864     }
 865 }
 866
 867 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 868     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 869         let kind = match *self.kind() {
 870             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 871             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
 872             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
 873             ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)),
 874             ty::Dynamic(trait_ty, region) => {
 875                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder))
 876             }
 877             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
 878             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.fold_with(folder)),
 879             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
 880             ty::Ref(r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl),
 881             ty::Generator(did, substs, movability) => {
 882                 ty::Generator(did, substs.fold_with(folder), movability)
 883             }
 884             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
 885             ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)),
 886             ty::Projection(data) => ty::Projection(data.fold_with(folder)),
 887             ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)),
 888
 889             ty::Bool
 890             | ty::Char
 891             | ty::Str
 892             | ty::Int(_)
 893             | ty::Uint(_)
 894             | ty::Float(_)
 895             | ty::Error(_)
 896             | ty::Infer(_)
 897             | ty::Param(..)
 898             | ty::Bound(..)
 899             | ty::Placeholder(..)
 900             | ty::Never
 901             | ty::Foreign(..) => return self,
 902         };
 903
 904         if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) }
 905     }
 906
 907     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 908         folder.fold_ty(self)
 909     }
 910
 911     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 912         match self.kind() {
 913             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 914             ty::Array(typ, sz) => {
 915                 typ.visit_with(visitor)?;
 916                 sz.visit_with(visitor)
 917             }
 918             ty::Slice(typ) => typ.visit_with(visitor),
 919             ty::Adt(_, substs) => substs.visit_with(visitor),
 920             ty::Dynamic(ref trait_ty, ref reg) => {
 921                 trait_ty.visit_with(visitor)?;
 922                 reg.visit_with(visitor)
 923             }
 924             ty::Tuple(ts) => ts.visit_with(visitor),
 925             ty::FnDef(_, substs) => substs.visit_with(visitor),
 926             ty::FnPtr(ref f) => f.visit_with(visitor),
 927             ty::Ref(r, ty, _) => {
 928                 r.visit_with(visitor)?;
 929                 ty.visit_with(visitor)
 930             }
 931             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 932             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 933             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 934             ty::Projection(ref data) => data.visit_with(visitor),
 935             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 936
 937             ty::Bool
 938             | ty::Char
 939             | ty::Str
 940             | ty::Int(_)
 941             | ty::Uint(_)
 942             | ty::Float(_)
 943             | ty::Error(_)
 944             | ty::Infer(_)
 945             | ty::Bound(..)
 946             | ty::Placeholder(..)
 947             | ty::Param(..)
 948             | ty::Never
 949             | ty::Foreign(..) => ControlFlow::CONTINUE,
 950         }
 951     }
 952
 953     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 954         visitor.visit_ty(self)
 955     }
 956 }
 957
 958 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
 959     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
 960         self
 961     }
 962
 963     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 964         folder.fold_region(self)
 965     }
 966
 967     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 968         ControlFlow::CONTINUE
 969     }
 970
 971     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 972         visitor.visit_region(*self)
 973     }
 974 }
 975
 976 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
 977     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 978         folder.fold_predicate(self)
 979     }
 980
 981     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
 982         let new = self.inner.kind.fold_with(folder);
 983         folder.tcx().reuse_or_mk_predicate(self, new)
 984     }
 985
 986     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 987         self.inner.kind.visit_with(visitor)
 988     }
 989
 990     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 991         visitor.visit_predicate(*self)
 992     }
 993
 994     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
 995         self.inner.outer_exclusive_binder > binder
 996     }
 997
 998     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
 999         self.inner.flags.intersects(flags)
1000     }
1001 }
1002
1003 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1004     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1005         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
1006     }
1007
1008     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1009         self.iter().try_for_each(|p| p.visit_with(visitor))
1010     }
1011 }
1012
1013 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1014     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1015         self.map_id(|x| x.fold_with(folder))
1016     }
1017
1018     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1019         self.iter().try_for_each(|t| t.visit_with(visitor))
1020     }
1021 }
1022
1023 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1024     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1025         let ty = self.ty.fold_with(folder);
1026         let val = self.val.fold_with(folder);
1027         if ty != self.ty || val != self.val {
1028             folder.tcx().mk_const(ty::Const { ty, val })
1029         } else {
1030             self
1031         }
1032     }
1033
1034     fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1035         folder.fold_const(self)
1036     }
1037
1038     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1039         self.ty.visit_with(visitor)?;
1040         self.val.visit_with(visitor)
1041     }
1042
1043     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1044         visitor.visit_const(self)
1045     }
1046 }
1047
1048 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1049     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1050         match self {
1051             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
1052             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
1053             ty::ConstKind::Unevaluated(uv) => ty::ConstKind::Unevaluated(uv.fold_with(folder)),
1054             ty::ConstKind::Value(_)
1055             | ty::ConstKind::Bound(..)
1056             | ty::ConstKind::Placeholder(..)
1057             | ty::ConstKind::Error(_) => self,
1058         }
1059     }
1060
1061     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1062         match *self {
1063             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1064             ty::ConstKind::Param(p) => p.visit_with(visitor),
1065             ty::ConstKind::Unevaluated(uv) => uv.visit_with(visitor),
1066             ty::ConstKind::Value(_)
1067             | ty::ConstKind::Bound(..)
1068             | ty::ConstKind::Placeholder(_)
1069             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1070         }
1071     }
1072 }
1073
1074 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1075     fn super_fold_with<F: TypeFolder<'tcx>>(self, _folder: &mut F) -> Self {
1076         self
1077     }
1078
1079     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1080         ControlFlow::CONTINUE
1081     }
1082 }
1083
1084 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
1085     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1086         ty::Unevaluated {
1087             def: self.def,
1088             substs_: Some(self.substs(folder.tcx()).fold_with(folder)),
1089             promoted: self.promoted,
1090         }
1091     }
1092
1093     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1094         visitor.visit_unevaluated_const(*self)
1095     }
1096
1097     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1098         if let Some(tcx) = visitor.tcx_for_anon_const_substs() {
1099             self.substs(tcx).visit_with(visitor)
1100         } else if let Some(substs) = self.substs_ {
1101             substs.visit_with(visitor)
1102         } else {
1103             debug!("ignoring default substs of `{:?}`", self.def);
1104             ControlFlow::CONTINUE
1105         }
1106     }
1107 }
1108
1109 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
1110     fn super_fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1111         ty::Unevaluated {
1112             def: self.def,
1113             substs_: Some(self.substs(folder.tcx()).fold_with(folder)),
1114             promoted: self.promoted,
1115         }
1116     }
1117
1118     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1119         visitor.visit_unevaluated_const(self.expand())
1120     }
1121
1122     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1123         if let Some(tcx) = visitor.tcx_for_anon_const_substs() {
1124             self.substs(tcx).visit_with(visitor)
1125         } else if let Some(substs) = self.substs_ {
1126             substs.visit_with(visitor)
1127         } else {
1128             debug!("ignoring default substs of `{:?}`", self.def);
1129             ControlFlow::CONTINUE
1130         }
1131     }
1132 }