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::{Field, ProjectionKind};
   7 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
   8 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
   9 use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
  10 use crate::ty::{self, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
  11 use rustc_data_structures::functor::IdFunctor;
  12 use rustc_hir as hir;
  13 use rustc_hir::def::Namespace;
  14 use rustc_index::vec::{Idx, IndexVec};
  15
  16 use std::fmt;
  17 use std::mem::ManuallyDrop;
  18 use std::ops::ControlFlow;
  19 use std::rc::Rc;
  20 use std::sync::Arc;
  21
  22 impl fmt::Debug for ty::TraitDef {
  23     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  24         ty::tls::with(|tcx| {
  25             with_no_trimmed_paths!({
  26                 f.write_str(
  27                     &FmtPrinter::new(tcx, Namespace::TypeNS)
  28                         .print_def_path(self.def_id, &[])?
  29                         .into_buffer(),
  30                 )
  31             })
  32         })
  33     }
  34 }
  35
  36 impl<'tcx> fmt::Debug for ty::AdtDef<'tcx> {
  37     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  38         ty::tls::with(|tcx| {
  39             with_no_trimmed_paths!({
  40                 f.write_str(
  41                     &FmtPrinter::new(tcx, Namespace::TypeNS)
  42                         .print_def_path(self.did(), &[])?
  43                         .into_buffer(),
  44                 )
  45             })
  46         })
  47     }
  48 }
  49
  50 impl fmt::Debug for ty::UpvarId {
  51     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  52         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  53         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  54     }
  55 }
  56
  57 impl<'tcx> fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  58     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  59         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
  60     }
  61 }
  62
  63 impl<'tcx> fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  64     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  65         write!(f, "{:?} -> {}", self.kind, self.target)
  66     }
  67 }
  68
  69 impl fmt::Debug for ty::BoundRegionKind {
  70     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  71         match *self {
  72             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  73             ty::BrNamed(did, name) => {
  74                 if did.is_crate_root() {
  75                     write!(f, "BrNamed({})", name)
  76                 } else {
  77                     write!(f, "BrNamed({:?}, {})", did, name)
  78                 }
  79             }
  80             ty::BrEnv => write!(f, "BrEnv"),
  81         }
  82     }
  83 }
  84
  85 impl fmt::Debug for ty::FreeRegion {
  86     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  87         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
  88     }
  89 }
  90
  91 impl<'tcx> fmt::Debug for ty::FnSig<'tcx> {
  92     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  93         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
  94     }
  95 }
  96
  97 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
  98     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  99         write!(f, "_#{}c", self.index)
 100     }
 101 }
 102
 103 impl fmt::Debug for ty::RegionVid {
 104     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 105         write!(f, "'_#{}r", self.index())
 106     }
 107 }
 108
 109 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
 110     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 111         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
 112     }
 113 }
 114
 115 impl<'tcx> fmt::Debug for Ty<'tcx> {
 116     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 117         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
 118     }
 119 }
 120
 121 impl fmt::Debug for ty::ParamTy {
 122     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 123         write!(f, "{}/#{}", self.name, self.index)
 124     }
 125 }
 126
 127 impl fmt::Debug for ty::ParamConst {
 128     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 129         write!(f, "{}/#{}", self.name, self.index)
 130     }
 131 }
 132
 133 impl<'tcx> fmt::Debug for ty::TraitPredicate<'tcx> {
 134     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 135         if let ty::BoundConstness::ConstIfConst = self.constness {
 136             write!(f, "~const ")?;
 137         }
 138         write!(f, "TraitPredicate({:?}, polarity:{:?})", self.trait_ref, self.polarity)
 139     }
 140 }
 141
 142 impl<'tcx> fmt::Debug for ty::ProjectionPredicate<'tcx> {
 143     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 144         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.term)
 145     }
 146 }
 147
 148 impl<'tcx> fmt::Debug for ty::Predicate<'tcx> {
 149     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 150         write!(f, "{:?}", self.kind())
 151     }
 152 }
 153
 154 impl<'tcx> fmt::Debug for ty::PredicateKind<'tcx> {
 155     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 156         match *self {
 157             ty::PredicateKind::Trait(ref a) => a.fmt(f),
 158             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 159             ty::PredicateKind::Coerce(ref pair) => pair.fmt(f),
 160             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 161             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 162             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 163             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 164             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 165                 write!(f, "ObjectSafe({:?})", trait_def_id)
 166             }
 167             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 168                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 169             }
 170             ty::PredicateKind::ConstEvaluatable(uv) => {
 171                 write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs)
 172             }
 173             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 174             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 175                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 176             }
 177         }
 178     }
 179 }
 180
 181 ///////////////////////////////////////////////////////////////////////////
 182 // Atomic structs
 183 //
 184 // For things that don't carry any arena-allocated data (and are
 185 // copy...), just add them to this list.
 186
 187 TrivialTypeTraversalAndLiftImpls! {
 188     (),
 189     bool,
 190     usize,
 191     ::rustc_target::abi::VariantIdx,
 192     u32,
 193     u64,
 194     String,
 195     crate::middle::region::Scope,
 196     crate::ty::FloatTy,
 197     ::rustc_ast::InlineAsmOptions,
 198     ::rustc_ast::InlineAsmTemplatePiece,
 199     ::rustc_ast::NodeId,
 200     ::rustc_span::symbol::Symbol,
 201     ::rustc_hir::def::Res,
 202     ::rustc_hir::def_id::DefId,
 203     ::rustc_hir::def_id::LocalDefId,
 204     ::rustc_hir::HirId,
 205     ::rustc_hir::MatchSource,
 206     ::rustc_hir::Mutability,
 207     ::rustc_hir::Unsafety,
 208     ::rustc_target::asm::InlineAsmRegOrRegClass,
 209     ::rustc_target::spec::abi::Abi,
 210     crate::mir::coverage::ExpressionOperandId,
 211     crate::mir::coverage::CounterValueReference,
 212     crate::mir::coverage::InjectedExpressionId,
 213     crate::mir::coverage::InjectedExpressionIndex,
 214     crate::mir::coverage::MappedExpressionIndex,
 215     crate::mir::Local,
 216     crate::mir::Promoted,
 217     crate::traits::Reveal,
 218     crate::ty::adjustment::AutoBorrowMutability,
 219     crate::ty::AdtKind,
 220     crate::ty::BoundConstness,
 221     // Including `BoundRegionKind` is a *bit* dubious, but direct
 222     // references to bound region appear in `ty::Error`, and aren't
 223     // really meant to be folded. In general, we can only fold a fully
 224     // general `Region`.
 225     crate::ty::BoundRegionKind,
 226     crate::ty::AssocItem,
 227     crate::ty::AssocKind,
 228     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 229     crate::ty::ClosureKind,
 230     crate::ty::FreeRegion,
 231     crate::ty::InferTy,
 232     crate::ty::IntVarValue,
 233     crate::ty::ParamConst,
 234     crate::ty::ParamTy,
 235     crate::ty::adjustment::PointerCast,
 236     crate::ty::RegionVid,
 237     crate::ty::UniverseIndex,
 238     crate::ty::Variance,
 239     ::rustc_span::Span,
 240     ::rustc_errors::ErrorGuaranteed,
 241 }
 242
 243 ///////////////////////////////////////////////////////////////////////////
 244 // Lift implementations
 245
 246 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 247 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 248     type Lifted = (A::Lifted, B::Lifted);
 249     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 250         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 251     }
 252 }
 253
 254 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 255     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 256     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 257         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 258     }
 259 }
 260
 261 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 262     type Lifted = Option<T::Lifted>;
 263     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 264         match self {
 265             Some(x) => tcx.lift(x).map(Some),
 266             None => Some(None),
 267         }
 268     }
 269 }
 270
 271 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 272     type Lifted = Result<T::Lifted, E::Lifted>;
 273     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 274         match self {
 275             Ok(x) => tcx.lift(x).map(Ok),
 276             Err(e) => tcx.lift(e).map(Err),
 277         }
 278     }
 279 }
 280
 281 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 282     type Lifted = Box<T::Lifted>;
 283     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 284         tcx.lift(*self).map(Box::new)
 285     }
 286 }
 287
 288 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 289     type Lifted = Rc<T::Lifted>;
 290     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 291         tcx.lift(self.as_ref().clone()).map(Rc::new)
 292     }
 293 }
 294
 295 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 296     type Lifted = Arc<T::Lifted>;
 297     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 298         tcx.lift(self.as_ref().clone()).map(Arc::new)
 299     }
 300 }
 301 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 302     type Lifted = Vec<T::Lifted>;
 303     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 304         self.into_iter().map(|v| tcx.lift(v)).collect()
 305     }
 306 }
 307
 308 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 309     type Lifted = IndexVec<I, T::Lifted>;
 310     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 311         self.into_iter().map(|e| tcx.lift(e)).collect()
 312     }
 313 }
 314
 315 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 316     type Lifted = ty::TraitRef<'tcx>;
 317     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 318         tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 319     }
 320 }
 321
 322 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 323     type Lifted = ty::ExistentialTraitRef<'tcx>;
 324     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 325         tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 326     }
 327 }
 328
 329 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 330     type Lifted = ty::ExistentialPredicate<'tcx>;
 331     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 332         match self {
 333             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 334             ty::ExistentialPredicate::Projection(x) => {
 335                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 336             }
 337             ty::ExistentialPredicate::AutoTrait(def_id) => {
 338                 Some(ty::ExistentialPredicate::AutoTrait(def_id))
 339             }
 340         }
 341     }
 342 }
 343
 344 impl<'a, 'tcx> Lift<'tcx> for Term<'a> {
 345     type Lifted = ty::Term<'tcx>;
 346     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 347         Some(
 348             match self.unpack() {
 349                 TermKind::Ty(ty) => TermKind::Ty(tcx.lift(ty)?),
 350                 TermKind::Const(c) => TermKind::Const(tcx.lift(c)?),
 351             }
 352             .pack(),
 353         )
 354     }
 355 }
 356
 357 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 358     type Lifted = ty::TraitPredicate<'tcx>;
 359     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 360         tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 361             trait_ref,
 362             constness: self.constness,
 363             polarity: self.polarity,
 364         })
 365     }
 366 }
 367
 368 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 369     type Lifted = ty::SubtypePredicate<'tcx>;
 370     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 371         tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 372             a_is_expected: self.a_is_expected,
 373             a,
 374             b,
 375         })
 376     }
 377 }
 378
 379 impl<'a, 'tcx> Lift<'tcx> for ty::CoercePredicate<'a> {
 380     type Lifted = ty::CoercePredicate<'tcx>;
 381     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::CoercePredicate<'tcx>> {
 382         tcx.lift((self.a, self.b)).map(|(a, b)| ty::CoercePredicate { a, b })
 383     }
 384 }
 385
 386 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 387     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 388     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 389         tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 390     }
 391 }
 392
 393 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 394     type Lifted = ty::ProjectionTy<'tcx>;
 395     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 396         tcx.lift(self.substs)
 397             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 398     }
 399 }
 400
 401 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 402     type Lifted = ty::ProjectionPredicate<'tcx>;
 403     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 404         tcx.lift((self.projection_ty, self.term))
 405             .map(|(projection_ty, term)| ty::ProjectionPredicate { projection_ty, term })
 406     }
 407 }
 408
 409 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 410     type Lifted = ty::ExistentialProjection<'tcx>;
 411     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 412         tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
 413             substs,
 414             term: tcx.lift(self.term).expect("type must lift when substs do"),
 415             item_def_id: self.item_def_id,
 416         })
 417     }
 418 }
 419
 420 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 421     type Lifted = ty::PredicateKind<'tcx>;
 422     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 423         match self {
 424             ty::PredicateKind::Trait(data) => tcx.lift(data).map(ty::PredicateKind::Trait),
 425             ty::PredicateKind::Subtype(data) => tcx.lift(data).map(ty::PredicateKind::Subtype),
 426             ty::PredicateKind::Coerce(data) => tcx.lift(data).map(ty::PredicateKind::Coerce),
 427             ty::PredicateKind::RegionOutlives(data) => {
 428                 tcx.lift(data).map(ty::PredicateKind::RegionOutlives)
 429             }
 430             ty::PredicateKind::TypeOutlives(data) => {
 431                 tcx.lift(data).map(ty::PredicateKind::TypeOutlives)
 432             }
 433             ty::PredicateKind::Projection(data) => {
 434                 tcx.lift(data).map(ty::PredicateKind::Projection)
 435             }
 436             ty::PredicateKind::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateKind::WellFormed),
 437             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 438                 tcx.lift(closure_substs).map(|closure_substs| {
 439                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind)
 440                 })
 441             }
 442             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 443                 Some(ty::PredicateKind::ObjectSafe(trait_def_id))
 444             }
 445             ty::PredicateKind::ConstEvaluatable(uv) => {
 446                 tcx.lift(uv).map(|uv| ty::PredicateKind::ConstEvaluatable(uv))
 447             }
 448             ty::PredicateKind::ConstEquate(c1, c2) => {
 449                 tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateKind::ConstEquate(c1, c2))
 450             }
 451             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 452                 tcx.lift(ty).map(ty::PredicateKind::TypeWellFormedFromEnv)
 453             }
 454         }
 455     }
 456 }
 457
 458 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<'a, T>
 459 where
 460     <T as Lift<'tcx>>::Lifted: TypeVisitable<'tcx>,
 461 {
 462     type Lifted = ty::Binder<'tcx, T::Lifted>;
 463     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 464         let bound_vars = tcx.lift(self.bound_vars());
 465         tcx.lift(self.skip_binder())
 466             .zip(bound_vars)
 467             .map(|(value, vars)| ty::Binder::bind_with_vars(value, vars))
 468     }
 469 }
 470
 471 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 472     type Lifted = ty::ParamEnv<'tcx>;
 473     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 474         tcx.lift(self.caller_bounds())
 475             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.constness()))
 476     }
 477 }
 478
 479 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 480     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 481     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 482         tcx.lift(self.param_env).and_then(|param_env| {
 483             tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 484         })
 485     }
 486 }
 487
 488 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 489     type Lifted = ty::ClosureSubsts<'tcx>;
 490     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 491         tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
 492     }
 493 }
 494
 495 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 496     type Lifted = ty::GeneratorSubsts<'tcx>;
 497     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 498         tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
 499     }
 500 }
 501
 502 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 503     type Lifted = ty::adjustment::Adjustment<'tcx>;
 504     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 505         let ty::adjustment::Adjustment { kind, target } = self;
 506         tcx.lift(kind).and_then(|kind| {
 507             tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
 508         })
 509     }
 510 }
 511
 512 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 513     type Lifted = ty::adjustment::Adjust<'tcx>;
 514     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 515         match self {
 516             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 517             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 518             ty::adjustment::Adjust::Deref(overloaded) => {
 519                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 520             }
 521             ty::adjustment::Adjust::Borrow(autoref) => {
 522                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 523             }
 524         }
 525     }
 526 }
 527
 528 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 529     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 530     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 531         tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
 532             region,
 533             mutbl: self.mutbl,
 534             span: self.span,
 535         })
 536     }
 537 }
 538
 539 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 540     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 541     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 542         match self {
 543             ty::adjustment::AutoBorrow::Ref(r, m) => {
 544                 tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 545             }
 546             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 547         }
 548     }
 549 }
 550
 551 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 552     type Lifted = ty::GenSig<'tcx>;
 553     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 554         tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
 555             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 556     }
 557 }
 558
 559 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 560     type Lifted = ty::FnSig<'tcx>;
 561     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 562         tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
 563             inputs_and_output: x,
 564             c_variadic: self.c_variadic,
 565             unsafety: self.unsafety,
 566             abi: self.abi,
 567         })
 568     }
 569 }
 570
 571 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 572     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 573     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 574         let ty::error::ExpectedFound { expected, found } = self;
 575         tcx.lift(expected).and_then(|expected| {
 576             tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
 577         })
 578     }
 579 }
 580
 581 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 582     type Lifted = ty::error::TypeError<'tcx>;
 583     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 584         use crate::ty::error::TypeError::*;
 585
 586         Some(match self {
 587             Mismatch => Mismatch,
 588             ConstnessMismatch(x) => ConstnessMismatch(x),
 589             PolarityMismatch(x) => PolarityMismatch(x),
 590             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 591             AbiMismatch(x) => AbiMismatch(x),
 592             Mutability => Mutability,
 593             ArgumentMutability(i) => ArgumentMutability(i),
 594             TupleSize(x) => TupleSize(x),
 595             FixedArraySize(x) => FixedArraySize(x),
 596             ArgCount => ArgCount,
 597             FieldMisMatch(x, y) => FieldMisMatch(x, y),
 598             RegionsDoesNotOutlive(a, b) => {
 599                 return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 600             }
 601             RegionsInsufficientlyPolymorphic(a, b) => {
 602                 return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 603             }
 604             RegionsOverlyPolymorphic(a, b) => {
 605                 return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
 606             }
 607             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 608             IntMismatch(x) => IntMismatch(x),
 609             FloatMismatch(x) => FloatMismatch(x),
 610             Traits(x) => Traits(x),
 611             VariadicMismatch(x) => VariadicMismatch(x),
 612             CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
 613             CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
 614             ProjectionMismatched(x) => ProjectionMismatched(x),
 615             ArgumentSorts(x, i) => return tcx.lift(x).map(|x| ArgumentSorts(x, i)),
 616             Sorts(x) => return tcx.lift(x).map(Sorts),
 617             ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
 618             ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
 619             IntrinsicCast => IntrinsicCast,
 620             TargetFeatureCast(x) => TargetFeatureCast(x),
 621             ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 622         })
 623     }
 624 }
 625
 626 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 627     type Lifted = ty::InstanceDef<'tcx>;
 628     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 629         match self {
 630             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 631             ty::InstanceDef::VTableShim(def_id) => Some(ty::InstanceDef::VTableShim(def_id)),
 632             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 633             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 634             ty::InstanceDef::FnPtrShim(def_id, ty) => {
 635                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 636             }
 637             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 638             ty::InstanceDef::ClosureOnceShim { call_once, track_caller } => {
 639                 Some(ty::InstanceDef::ClosureOnceShim { call_once, track_caller })
 640             }
 641             ty::InstanceDef::DropGlue(def_id, ty) => {
 642                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 643             }
 644             ty::InstanceDef::CloneShim(def_id, ty) => {
 645                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 646             }
 647         }
 648     }
 649 }
 650
 651 impl<'tcx> Lift<'tcx> for Field {
 652     type Lifted = Field;
 653     fn lift_to_tcx(self, _tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 654         Some(self)
 655     }
 656 }
 657
 658 impl<'tcx> Lift<'tcx> for crate::mir::ReturnConstraint {
 659     type Lifted = crate::mir::ReturnConstraint;
 660     fn lift_to_tcx(self, _tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 661         Some(self)
 662     }
 663 }
 664
 665 ///////////////////////////////////////////////////////////////////////////
 666 // TypeFoldable implementations.
 667
 668 /// AdtDefs are basically the same as a DefId.
 669 impl<'tcx> TypeFoldable<'tcx> for ty::AdtDef<'tcx> {
 670     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
 671         Ok(self)
 672     }
 673 }
 674
 675 impl<'tcx> TypeVisitable<'tcx> for ty::AdtDef<'tcx> {
 676     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 677         ControlFlow::CONTINUE
 678     }
 679 }
 680
 681 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 682     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 683         self,
 684         folder: &mut F,
 685     ) -> Result<(T, U), F::Error> {
 686         Ok((self.0.try_fold_with(folder)?, self.1.try_fold_with(folder)?))
 687     }
 688 }
 689
 690 impl<'tcx, T: TypeVisitable<'tcx>, U: TypeVisitable<'tcx>> TypeVisitable<'tcx> for (T, U) {
 691     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 692         self.0.visit_with(visitor)?;
 693         self.1.visit_with(visitor)
 694     }
 695 }
 696
 697 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 698     for (A, B, C)
 699 {
 700     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 701         self,
 702         folder: &mut F,
 703     ) -> Result<(A, B, C), F::Error> {
 704         Ok((
 705             self.0.try_fold_with(folder)?,
 706             self.1.try_fold_with(folder)?,
 707             self.2.try_fold_with(folder)?,
 708         ))
 709     }
 710 }
 711
 712 impl<'tcx, A: TypeVisitable<'tcx>, B: TypeVisitable<'tcx>, C: TypeVisitable<'tcx>>
 713     TypeVisitable<'tcx> for (A, B, C)
 714 {
 715     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 716         self.0.visit_with(visitor)?;
 717         self.1.visit_with(visitor)?;
 718         self.2.visit_with(visitor)
 719     }
 720 }
 721
 722 EnumTypeTraversalImpl! {
 723     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 724         (Some)(a),
 725         (None),
 726     } where T: TypeFoldable<'tcx>
 727 }
 728 EnumTypeTraversalImpl! {
 729     impl<'tcx, T> TypeVisitable<'tcx> for Option<T> {
 730         (Some)(a),
 731         (None),
 732     } where T: TypeVisitable<'tcx>
 733 }
 734
 735 EnumTypeTraversalImpl! {
 736     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 737         (Ok)(a),
 738         (Err)(a),
 739     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 740 }
 741 EnumTypeTraversalImpl! {
 742     impl<'tcx, T, E> TypeVisitable<'tcx> for Result<T, E> {
 743         (Ok)(a),
 744         (Err)(a),
 745     } where T: TypeVisitable<'tcx>, E: TypeVisitable<'tcx>,
 746 }
 747
 748 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 749     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 750         mut self,
 751         folder: &mut F,
 752     ) -> Result<Self, F::Error> {
 753         // We merely want to replace the contained `T`, if at all possible,
 754         // so that we don't needlessly allocate a new `Rc` or indeed clone
 755         // the contained type.
 756         unsafe {
 757             // First step is to ensure that we have a unique reference to
 758             // the contained type, which `Rc::make_mut` will accomplish (by
 759             // allocating a new `Rc` and cloning the `T` only if required).
 760             // This is done *before* casting to `Rc<ManuallyDrop<T>>` so that
 761             // panicking during `make_mut` does not leak the `T`.
 762             Rc::make_mut(&mut self);
 763
 764             // Casting to `Rc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 765             // is `repr(transparent)`.
 766             let ptr = Rc::into_raw(self).cast::<ManuallyDrop<T>>();
 767             let mut unique = Rc::from_raw(ptr);
 768
 769             // Call to `Rc::make_mut` above guarantees that `unique` is the
 770             // sole reference to the contained value, so we can avoid doing
 771             // a checked `get_mut` here.
 772             let slot = Rc::get_mut_unchecked(&mut unique);
 773
 774             // Semantically move the contained type out from `unique`, fold
 775             // it, then move the folded value back into `unique`.  Should
 776             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 777             // value is not re-dropped.
 778             let owned = ManuallyDrop::take(slot);
 779             let folded = owned.try_fold_with(folder)?;
 780             *slot = ManuallyDrop::new(folded);
 781
 782             // Cast back to `Rc<T>`.
 783             Ok(Rc::from_raw(Rc::into_raw(unique).cast()))
 784         }
 785     }
 786 }
 787
 788 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Rc<T> {
 789     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 790         (**self).visit_with(visitor)
 791     }
 792 }
 793
 794 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 795     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 796         mut self,
 797         folder: &mut F,
 798     ) -> Result<Self, F::Error> {
 799         // We merely want to replace the contained `T`, if at all possible,
 800         // so that we don't needlessly allocate a new `Arc` or indeed clone
 801         // the contained type.
 802         unsafe {
 803             // First step is to ensure that we have a unique reference to
 804             // the contained type, which `Arc::make_mut` will accomplish (by
 805             // allocating a new `Arc` and cloning the `T` only if required).
 806             // This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
 807             // panicking during `make_mut` does not leak the `T`.
 808             Arc::make_mut(&mut self);
 809
 810             // Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 811             // is `repr(transparent)`.
 812             let ptr = Arc::into_raw(self).cast::<ManuallyDrop<T>>();
 813             let mut unique = Arc::from_raw(ptr);
 814
 815             // Call to `Arc::make_mut` above guarantees that `unique` is the
 816             // sole reference to the contained value, so we can avoid doing
 817             // a checked `get_mut` here.
 818             let slot = Arc::get_mut_unchecked(&mut unique);
 819
 820             // Semantically move the contained type out from `unique`, fold
 821             // it, then move the folded value back into `unique`.  Should
 822             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 823             // value is not re-dropped.
 824             let owned = ManuallyDrop::take(slot);
 825             let folded = owned.try_fold_with(folder)?;
 826             *slot = ManuallyDrop::new(folded);
 827
 828             // Cast back to `Arc<T>`.
 829             Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
 830         }
 831     }
 832 }
 833
 834 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Arc<T> {
 835     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 836         (**self).visit_with(visitor)
 837     }
 838 }
 839
 840 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 841     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 842         self.try_map_id(|value| value.try_fold_with(folder))
 843     }
 844 }
 845
 846 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<T> {
 847     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 848         (**self).visit_with(visitor)
 849     }
 850 }
 851
 852 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 853     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 854         self.try_map_id(|t| t.try_fold_with(folder))
 855     }
 856 }
 857
 858 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Vec<T> {
 859     fn 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: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &[T] {
 865     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 866         self.iter().try_for_each(|t| t.visit_with(visitor))
 867     }
 868 }
 869
 870 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 871     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 872         self.try_map_id(|t| t.try_fold_with(folder))
 873     }
 874 }
 875
 876 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<[T]> {
 877     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 878         self.iter().try_for_each(|t| t.visit_with(visitor))
 879     }
 880 }
 881
 882 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::EarlyBinder<T> {
 883     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 884         self.try_map_bound(|ty| ty.try_fold_with(folder))
 885     }
 886 }
 887
 888 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for ty::EarlyBinder<T> {
 889     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 890         self.as_ref().0.visit_with(visitor)
 891     }
 892 }
 893
 894 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 895     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 896         folder.try_fold_binder(self)
 897     }
 898 }
 899
 900 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for ty::Binder<'tcx, T> {
 901     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 902         visitor.visit_binder(self)
 903     }
 904 }
 905
 906 impl<'tcx, T: TypeFoldable<'tcx>> TypeSuperFoldable<'tcx> for ty::Binder<'tcx, T> {
 907     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 908         self,
 909         folder: &mut F,
 910     ) -> Result<Self, F::Error> {
 911         self.try_map_bound(|ty| ty.try_fold_with(folder))
 912     }
 913 }
 914
 915 impl<'tcx, T: TypeVisitable<'tcx>> TypeSuperVisitable<'tcx> for ty::Binder<'tcx, T> {
 916     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 917         self.as_ref().skip_binder().visit_with(visitor)
 918     }
 919 }
 920
 921 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 922     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 923         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 924     }
 925 }
 926
 927 impl<'tcx> TypeVisitable<'tcx>
 928     for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>
 929 {
 930     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 931         self.iter().try_for_each(|p| p.visit_with(visitor))
 932     }
 933 }
 934
 935 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 936     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 937         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 938     }
 939 }
 940
 941 impl<'tcx> TypeVisitable<'tcx> for &'tcx ty::List<ProjectionKind> {
 942     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 943         self.iter().try_for_each(|t| t.visit_with(visitor))
 944     }
 945 }
 946
 947 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 948     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 949         use crate::ty::InstanceDef::*;
 950         Ok(Self {
 951             substs: self.substs.try_fold_with(folder)?,
 952             def: match self.def {
 953                 Item(def) => Item(def.try_fold_with(folder)?),
 954                 VTableShim(did) => VTableShim(did.try_fold_with(folder)?),
 955                 ReifyShim(did) => ReifyShim(did.try_fold_with(folder)?),
 956                 Intrinsic(did) => Intrinsic(did.try_fold_with(folder)?),
 957                 FnPtrShim(did, ty) => {
 958                     FnPtrShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 959                 }
 960                 Virtual(did, i) => Virtual(did.try_fold_with(folder)?, i),
 961                 ClosureOnceShim { call_once, track_caller } => {
 962                     ClosureOnceShim { call_once: call_once.try_fold_with(folder)?, track_caller }
 963                 }
 964                 DropGlue(did, ty) => {
 965                     DropGlue(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 966                 }
 967                 CloneShim(did, ty) => {
 968                     CloneShim(did.try_fold_with(folder)?, ty.try_fold_with(folder)?)
 969                 }
 970             },
 971         })
 972     }
 973 }
 974
 975 impl<'tcx> TypeVisitable<'tcx> for ty::instance::Instance<'tcx> {
 976     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 977         use crate::ty::InstanceDef::*;
 978         self.substs.visit_with(visitor)?;
 979         match self.def {
 980             Item(def) => def.visit_with(visitor),
 981             VTableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 982                 did.visit_with(visitor)
 983             }
 984             FnPtrShim(did, ty) | CloneShim(did, ty) => {
 985                 did.visit_with(visitor)?;
 986                 ty.visit_with(visitor)
 987             }
 988             DropGlue(did, ty) => {
 989                 did.visit_with(visitor)?;
 990                 ty.visit_with(visitor)
 991             }
 992             ClosureOnceShim { call_once, track_caller: _ } => call_once.visit_with(visitor),
 993         }
 994     }
 995 }
 996
 997 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 998     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 999         Ok(Self { instance: self.instance.try_fold_with(folder)?, promoted: self.promoted })
1000     }
1001 }
1002
1003 impl<'tcx> TypeVisitable<'tcx> for interpret::GlobalId<'tcx> {
1004     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1005         self.instance.visit_with(visitor)
1006     }
1007 }
1008
1009 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
1010     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1011         folder.try_fold_ty(self)
1012     }
1013 }
1014
1015 impl<'tcx> TypeVisitable<'tcx> for Ty<'tcx> {
1016     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1017         visitor.visit_ty(*self)
1018     }
1019 }
1020
1021 impl<'tcx> TypeSuperFoldable<'tcx> for Ty<'tcx> {
1022     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1023         self,
1024         folder: &mut F,
1025     ) -> Result<Self, F::Error> {
1026         let kind = match *self.kind() {
1027             ty::RawPtr(tm) => ty::RawPtr(tm.try_fold_with(folder)?),
1028             ty::Array(typ, sz) => ty::Array(typ.try_fold_with(folder)?, sz.try_fold_with(folder)?),
1029             ty::Slice(typ) => ty::Slice(typ.try_fold_with(folder)?),
1030             ty::Adt(tid, substs) => ty::Adt(tid, substs.try_fold_with(folder)?),
1031             ty::Dynamic(trait_ty, region, representation) => ty::Dynamic(
1032                 trait_ty.try_fold_with(folder)?,
1033                 region.try_fold_with(folder)?,
1034                 representation,
1035             ),
1036             ty::Tuple(ts) => ty::Tuple(ts.try_fold_with(folder)?),
1037             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.try_fold_with(folder)?),
1038             ty::FnPtr(f) => ty::FnPtr(f.try_fold_with(folder)?),
1039             ty::Ref(r, ty, mutbl) => {
1040                 ty::Ref(r.try_fold_with(folder)?, ty.try_fold_with(folder)?, mutbl)
1041             }
1042             ty::Generator(did, substs, movability) => {
1043                 ty::Generator(did, substs.try_fold_with(folder)?, movability)
1044             }
1045             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.try_fold_with(folder)?),
1046             ty::Closure(did, substs) => ty::Closure(did, substs.try_fold_with(folder)?),
1047             ty::Projection(data) => ty::Projection(data.try_fold_with(folder)?),
1048             ty::Opaque(did, substs) => ty::Opaque(did, substs.try_fold_with(folder)?),
1049
1050             ty::Bool
1051             | ty::Char
1052             | ty::Str
1053             | ty::Int(_)
1054             | ty::Uint(_)
1055             | ty::Float(_)
1056             | ty::Error(_)
1057             | ty::Infer(_)
1058             | ty::Param(..)
1059             | ty::Bound(..)
1060             | ty::Placeholder(..)
1061             | ty::Never
1062             | ty::Foreign(..) => return Ok(self),
1063         };
1064
1065         Ok(if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) })
1066     }
1067 }
1068
1069 impl<'tcx> TypeSuperVisitable<'tcx> for Ty<'tcx> {
1070     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1071         match self.kind() {
1072             ty::RawPtr(ref tm) => tm.visit_with(visitor),
1073             ty::Array(typ, sz) => {
1074                 typ.visit_with(visitor)?;
1075                 sz.visit_with(visitor)
1076             }
1077             ty::Slice(typ) => typ.visit_with(visitor),
1078             ty::Adt(_, substs) => substs.visit_with(visitor),
1079             ty::Dynamic(ref trait_ty, ref reg, _) => {
1080                 trait_ty.visit_with(visitor)?;
1081                 reg.visit_with(visitor)
1082             }
1083             ty::Tuple(ts) => ts.visit_with(visitor),
1084             ty::FnDef(_, substs) => substs.visit_with(visitor),
1085             ty::FnPtr(ref f) => f.visit_with(visitor),
1086             ty::Ref(r, ty, _) => {
1087                 r.visit_with(visitor)?;
1088                 ty.visit_with(visitor)
1089             }
1090             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
1091             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
1092             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
1093             ty::Projection(ref data) => data.visit_with(visitor),
1094             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
1095
1096             ty::Bool
1097             | ty::Char
1098             | ty::Str
1099             | ty::Int(_)
1100             | ty::Uint(_)
1101             | ty::Float(_)
1102             | ty::Error(_)
1103             | ty::Infer(_)
1104             | ty::Bound(..)
1105             | ty::Placeholder(..)
1106             | ty::Param(..)
1107             | ty::Never
1108             | ty::Foreign(..) => ControlFlow::CONTINUE,
1109         }
1110     }
1111 }
1112
1113 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1114     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1115         folder.try_fold_region(self)
1116     }
1117 }
1118
1119 impl<'tcx> TypeVisitable<'tcx> for ty::Region<'tcx> {
1120     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1121         visitor.visit_region(*self)
1122     }
1123 }
1124
1125 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Region<'tcx> {
1126     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1127         self,
1128         _folder: &mut F,
1129     ) -> Result<Self, F::Error> {
1130         Ok(self)
1131     }
1132 }
1133
1134 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Region<'tcx> {
1135     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1136         ControlFlow::CONTINUE
1137     }
1138 }
1139
1140 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1141     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1142         folder.try_fold_predicate(self)
1143     }
1144 }
1145
1146 impl<'tcx> TypeVisitable<'tcx> for ty::Predicate<'tcx> {
1147     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1148         visitor.visit_predicate(*self)
1149     }
1150
1151     #[inline]
1152     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1153         self.outer_exclusive_binder() > binder
1154     }
1155
1156     #[inline]
1157     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1158         self.flags().intersects(flags)
1159     }
1160 }
1161
1162 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Predicate<'tcx> {
1163     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1164         self,
1165         folder: &mut F,
1166     ) -> Result<Self, F::Error> {
1167         let new = self.kind().try_fold_with(folder)?;
1168         Ok(folder.tcx().reuse_or_mk_predicate(self, new))
1169     }
1170 }
1171
1172 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Predicate<'tcx> {
1173     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1174         self.kind().visit_with(visitor)
1175     }
1176 }
1177
1178 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1179     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1180         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
1181     }
1182 }
1183
1184 impl<'tcx> TypeVisitable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1185     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1186         self.iter().try_for_each(|p| p.visit_with(visitor))
1187     }
1188 }
1189
1190 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1191     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1192         self.try_map_id(|x| x.try_fold_with(folder))
1193     }
1194 }
1195
1196 impl<'tcx, T: TypeVisitable<'tcx>, I: Idx> TypeVisitable<'tcx> for IndexVec<I, T> {
1197     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1198         self.iter().try_for_each(|t| t.visit_with(visitor))
1199     }
1200 }
1201
1202 impl<'tcx> TypeFoldable<'tcx> for ty::Const<'tcx> {
1203     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1204         folder.try_fold_const(self)
1205     }
1206 }
1207
1208 impl<'tcx> TypeVisitable<'tcx> for ty::Const<'tcx> {
1209     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1210         visitor.visit_const(*self)
1211     }
1212 }
1213
1214 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Const<'tcx> {
1215     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1216         self,
1217         folder: &mut F,
1218     ) -> Result<Self, F::Error> {
1219         let ty = self.ty().try_fold_with(folder)?;
1220         let kind = self.kind().try_fold_with(folder)?;
1221         if ty != self.ty() || kind != self.kind() {
1222             Ok(folder.tcx().mk_const(ty::ConstS { ty, kind }))
1223         } else {
1224             Ok(self)
1225         }
1226     }
1227 }
1228
1229 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Const<'tcx> {
1230     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1231         self.ty().visit_with(visitor)?;
1232         self.kind().visit_with(visitor)
1233     }
1234 }
1235
1236 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1237     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1238         Ok(match self {
1239             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.try_fold_with(folder)?),
1240             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.try_fold_with(folder)?),
1241             ty::ConstKind::Unevaluated(uv) => ty::ConstKind::Unevaluated(uv.try_fold_with(folder)?),
1242             ty::ConstKind::Value(_)
1243             | ty::ConstKind::Bound(..)
1244             | ty::ConstKind::Placeholder(..)
1245             | ty::ConstKind::Error(_) => self,
1246         })
1247     }
1248 }
1249
1250 impl<'tcx> TypeVisitable<'tcx> for ty::ConstKind<'tcx> {
1251     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1252         match *self {
1253             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1254             ty::ConstKind::Param(p) => p.visit_with(visitor),
1255             ty::ConstKind::Unevaluated(uv) => uv.visit_with(visitor),
1256             ty::ConstKind::Value(_)
1257             | ty::ConstKind::Bound(..)
1258             | ty::ConstKind::Placeholder(_)
1259             | ty::ConstKind::Error(_) => ControlFlow::CONTINUE,
1260         }
1261     }
1262 }
1263
1264 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1265     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
1266         Ok(self)
1267     }
1268 }
1269
1270 impl<'tcx> TypeVisitable<'tcx> for InferConst<'tcx> {
1271     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
1272         ControlFlow::CONTINUE
1273     }
1274 }
1275
1276 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx> {
1277     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1278         folder.try_fold_unevaluated(self)
1279     }
1280 }
1281
1282 impl<'tcx> TypeVisitable<'tcx> for ty::Unevaluated<'tcx> {
1283     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1284         visitor.visit_unevaluated(*self)
1285     }
1286 }
1287
1288 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Unevaluated<'tcx> {
1289     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
1290         self,
1291         folder: &mut F,
1292     ) -> Result<Self, F::Error> {
1293         Ok(ty::Unevaluated {
1294             def: self.def,
1295             substs: self.substs.try_fold_with(folder)?,
1296             promoted: self.promoted,
1297         })
1298     }
1299 }
1300
1301 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Unevaluated<'tcx> {
1302     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1303         self.substs.visit_with(visitor)
1304     }
1305 }
1306
1307 impl<'tcx> TypeFoldable<'tcx> for ty::Unevaluated<'tcx, ()> {
1308     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
1309         Ok(self.expand().try_fold_with(folder)?.shrink())
1310     }
1311 }
1312
1313 impl<'tcx> TypeVisitable<'tcx> for ty::Unevaluated<'tcx, ()> {
1314     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1315         self.expand().visit_with(visitor)
1316     }
1317 }
1318
1319 impl<'tcx> TypeFoldable<'tcx> for hir::Constness {
1320     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _: &mut F) -> Result<Self, F::Error> {
1321         Ok(self)
1322     }
1323 }
1324
1325 impl<'tcx> TypeVisitable<'tcx> for hir::Constness {
1326     fn visit_with<V: TypeVisitor<'tcx>>(&self, _: &mut V) -> ControlFlow<V::BreakTy> {
1327         ControlFlow::CONTINUE
1328     }
1329 }