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_hir as hir;
  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 smallvec::SmallVec;
  16 use std::fmt;
  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::BoundRegion {
  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::Variance {
 114     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 115         f.write_str(match *self {
 116             ty::Covariant => "+",
 117             ty::Contravariant => "-",
 118             ty::Invariant => "o",
 119             ty::Bivariant => "*",
 120         })
 121     }
 122 }
 123
 124 impl fmt::Debug for ty::FnSig<'tcx> {
 125     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 126         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 127     }
 128 }
 129
 130 impl fmt::Debug for ty::TyVid {
 131     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 132         write!(f, "_#{}t", self.index)
 133     }
 134 }
 135
 136 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 137     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 138         write!(f, "_#{}c", self.index)
 139     }
 140 }
 141
 142 impl fmt::Debug for ty::IntVid {
 143     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 144         write!(f, "_#{}i", self.index)
 145     }
 146 }
 147
 148 impl fmt::Debug for ty::FloatVid {
 149     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 150         write!(f, "_#{}f", self.index)
 151     }
 152 }
 153
 154 impl fmt::Debug for ty::RegionVid {
 155     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 156         write!(f, "'_#{}r", self.index())
 157     }
 158 }
 159
 160 impl fmt::Debug for ty::InferTy {
 161     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 162         match *self {
 163             ty::TyVar(ref v) => v.fmt(f),
 164             ty::IntVar(ref v) => v.fmt(f),
 165             ty::FloatVar(ref v) => v.fmt(f),
 166             ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
 167             ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
 168             ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v),
 169         }
 170     }
 171 }
 172
 173 impl fmt::Debug for ty::IntVarValue {
 174     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 175         match *self {
 176             ty::IntType(ref v) => v.fmt(f),
 177             ty::UintType(ref v) => v.fmt(f),
 178         }
 179     }
 180 }
 181
 182 impl fmt::Debug for ty::FloatVarValue {
 183     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 184         self.0.fmt(f)
 185     }
 186 }
 187
 188 impl fmt::Debug for ty::TraitRef<'tcx> {
 189     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 190         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 191     }
 192 }
 193
 194 impl fmt::Debug for Ty<'tcx> {
 195     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 196         with_no_trimmed_paths(|| fmt::Display::fmt(self, f))
 197     }
 198 }
 199
 200 impl fmt::Debug for ty::ParamTy {
 201     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 202         write!(f, "{}/#{}", self.name, self.index)
 203     }
 204 }
 205
 206 impl fmt::Debug for ty::ParamConst {
 207     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 208         write!(f, "{}/#{}", self.name, self.index)
 209     }
 210 }
 211
 212 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 213     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 214         write!(f, "TraitPredicate({:?})", self.trait_ref)
 215     }
 216 }
 217
 218 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 219     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 220         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 221     }
 222 }
 223
 224 impl fmt::Debug for ty::Predicate<'tcx> {
 225     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 226         write!(f, "{:?}", self.kind())
 227     }
 228 }
 229
 230 impl fmt::Debug for ty::PredicateKind<'tcx> {
 231     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 232         match *self {
 233             ty::PredicateKind::ForAll(binder) => write!(f, "ForAll({:?})", binder),
 234             ty::PredicateKind::Atom(atom) => write!(f, "{:?}", atom),
 235         }
 236     }
 237 }
 238
 239 impl fmt::Debug for ty::PredicateAtom<'tcx> {
 240     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 241         match *self {
 242             ty::PredicateAtom::Trait(ref a, constness) => {
 243                 if let hir::Constness::Const = constness {
 244                     write!(f, "const ")?;
 245                 }
 246                 a.fmt(f)
 247             }
 248             ty::PredicateAtom::Subtype(ref pair) => pair.fmt(f),
 249             ty::PredicateAtom::RegionOutlives(ref pair) => pair.fmt(f),
 250             ty::PredicateAtom::TypeOutlives(ref pair) => pair.fmt(f),
 251             ty::PredicateAtom::Projection(ref pair) => pair.fmt(f),
 252             ty::PredicateAtom::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 253             ty::PredicateAtom::ObjectSafe(trait_def_id) => {
 254                 write!(f, "ObjectSafe({:?})", trait_def_id)
 255             }
 256             ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => {
 257                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 258             }
 259             ty::PredicateAtom::ConstEvaluatable(def_id, substs) => {
 260                 write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
 261             }
 262             ty::PredicateAtom::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 263             ty::PredicateAtom::TypeWellFormedFromEnv(ty) => {
 264                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 265             }
 266         }
 267     }
 268 }
 269
 270 ///////////////////////////////////////////////////////////////////////////
 271 // Atomic structs
 272 //
 273 // For things that don't carry any arena-allocated data (and are
 274 // copy...), just add them to this list.
 275
 276 CloneTypeFoldableAndLiftImpls! {
 277     (),
 278     bool,
 279     usize,
 280     ::rustc_target::abi::VariantIdx,
 281     u32,
 282     u64,
 283     String,
 284     crate::middle::region::Scope,
 285     ::rustc_ast::FloatTy,
 286     ::rustc_ast::InlineAsmOptions,
 287     ::rustc_ast::InlineAsmTemplatePiece,
 288     ::rustc_ast::NodeId,
 289     ::rustc_span::symbol::Symbol,
 290     ::rustc_hir::def::Res,
 291     ::rustc_hir::def_id::DefId,
 292     ::rustc_hir::def_id::LocalDefId,
 293     ::rustc_hir::HirId,
 294     ::rustc_hir::LlvmInlineAsmInner,
 295     ::rustc_hir::MatchSource,
 296     ::rustc_hir::Mutability,
 297     ::rustc_hir::Unsafety,
 298     ::rustc_target::asm::InlineAsmRegOrRegClass,
 299     ::rustc_target::spec::abi::Abi,
 300     crate::mir::coverage::ExpressionOperandId,
 301     crate::mir::coverage::CounterValueReference,
 302     crate::mir::coverage::InjectedExpressionIndex,
 303     crate::mir::coverage::MappedExpressionIndex,
 304     crate::mir::Local,
 305     crate::mir::Promoted,
 306     crate::traits::Reveal,
 307     crate::ty::adjustment::AutoBorrowMutability,
 308     crate::ty::AdtKind,
 309     // Including `BoundRegion` is a *bit* dubious, but direct
 310     // references to bound region appear in `ty::Error`, and aren't
 311     // really meant to be folded. In general, we can only fold a fully
 312     // general `Region`.
 313     crate::ty::BoundRegion,
 314     crate::ty::AssocItem,
 315     crate::ty::Placeholder<crate::ty::BoundRegion>,
 316     crate::ty::ClosureKind,
 317     crate::ty::FreeRegion,
 318     crate::ty::InferTy,
 319     crate::ty::IntVarValue,
 320     crate::ty::ParamConst,
 321     crate::ty::ParamTy,
 322     crate::ty::adjustment::PointerCast,
 323     crate::ty::RegionVid,
 324     crate::ty::UniverseIndex,
 325     crate::ty::Variance,
 326     ::rustc_span::Span,
 327 }
 328
 329 ///////////////////////////////////////////////////////////////////////////
 330 // Lift implementations
 331
 332 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 333 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 334     type Lifted = (A::Lifted, B::Lifted);
 335     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 336         tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b)))
 337     }
 338 }
 339
 340 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 341     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 342     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 343         tcx.lift(&self.0)
 344             .and_then(|a| tcx.lift(&self.1).and_then(|b| tcx.lift(&self.2).map(|c| (a, b, c))))
 345     }
 346 }
 347
 348 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 349     type Lifted = Option<T::Lifted>;
 350     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 351         match *self {
 352             Some(ref x) => tcx.lift(x).map(Some),
 353             None => Some(None),
 354         }
 355     }
 356 }
 357
 358 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 359     type Lifted = Result<T::Lifted, E::Lifted>;
 360     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 361         match *self {
 362             Ok(ref x) => tcx.lift(x).map(Ok),
 363             Err(ref e) => tcx.lift(e).map(Err),
 364         }
 365     }
 366 }
 367
 368 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 369     type Lifted = Box<T::Lifted>;
 370     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 371         tcx.lift(&**self).map(Box::new)
 372     }
 373 }
 374
 375 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Rc<T> {
 376     type Lifted = Rc<T::Lifted>;
 377     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 378         tcx.lift(&**self).map(Rc::new)
 379     }
 380 }
 381
 382 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Arc<T> {
 383     type Lifted = Arc<T::Lifted>;
 384     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 385         tcx.lift(&**self).map(Arc::new)
 386     }
 387 }
 388
 389 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] {
 390     type Lifted = Vec<T::Lifted>;
 391     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 392         // type annotation needed to inform `projection_must_outlive`
 393         let mut result: Vec<<T as Lift<'tcx>>::Lifted> = Vec::with_capacity(self.len());
 394         for x in self {
 395             if let Some(value) = tcx.lift(x) {
 396                 result.push(value);
 397             } else {
 398                 return None;
 399             }
 400         }
 401         Some(result)
 402     }
 403 }
 404
 405 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 406     type Lifted = Vec<T::Lifted>;
 407     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 408         tcx.lift(&self[..])
 409     }
 410 }
 411
 412 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 413     type Lifted = IndexVec<I, T::Lifted>;
 414     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 415         self.iter().map(|e| tcx.lift(e)).collect()
 416     }
 417 }
 418
 419 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 420     type Lifted = ty::TraitRef<'tcx>;
 421     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 422         tcx.lift(&self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 423     }
 424 }
 425
 426 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 427     type Lifted = ty::ExistentialTraitRef<'tcx>;
 428     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 429         tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 430     }
 431 }
 432
 433 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 434     type Lifted = ty::ExistentialPredicate<'tcx>;
 435     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 436         match self {
 437             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 438             ty::ExistentialPredicate::Projection(x) => {
 439                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 440             }
 441             ty::ExistentialPredicate::AutoTrait(def_id) => {
 442                 Some(ty::ExistentialPredicate::AutoTrait(*def_id))
 443             }
 444         }
 445     }
 446 }
 447
 448 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 449     type Lifted = ty::TraitPredicate<'tcx>;
 450     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 451         tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref })
 452     }
 453 }
 454
 455 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 456     type Lifted = ty::SubtypePredicate<'tcx>;
 457     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 458         tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 459             a_is_expected: self.a_is_expected,
 460             a,
 461             b,
 462         })
 463     }
 464 }
 465
 466 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 467     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 468     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 469         tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 470     }
 471 }
 472
 473 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 474     type Lifted = ty::ProjectionTy<'tcx>;
 475     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 476         tcx.lift(&self.substs)
 477             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 478     }
 479 }
 480
 481 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 482     type Lifted = ty::ProjectionPredicate<'tcx>;
 483     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 484         tcx.lift(&(self.projection_ty, self.ty))
 485             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 486     }
 487 }
 488
 489 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 490     type Lifted = ty::ExistentialProjection<'tcx>;
 491     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 492         tcx.lift(&self.substs).map(|substs| ty::ExistentialProjection {
 493             substs,
 494             ty: tcx.lift(&self.ty).expect("type must lift when substs do"),
 495             item_def_id: self.item_def_id,
 496         })
 497     }
 498 }
 499
 500 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 501     type Lifted = ty::PredicateKind<'tcx>;
 502     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 503         match self {
 504             ty::PredicateKind::ForAll(binder) => tcx.lift(binder).map(ty::PredicateKind::ForAll),
 505             ty::PredicateKind::Atom(atom) => tcx.lift(atom).map(ty::PredicateKind::Atom),
 506         }
 507     }
 508 }
 509
 510 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> {
 511     type Lifted = ty::PredicateAtom<'tcx>;
 512     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 513         match *self {
 514             ty::PredicateAtom::Trait(ref data, constness) => {
 515                 tcx.lift(data).map(|data| ty::PredicateAtom::Trait(data, constness))
 516             }
 517             ty::PredicateAtom::Subtype(ref data) => tcx.lift(data).map(ty::PredicateAtom::Subtype),
 518             ty::PredicateAtom::RegionOutlives(ref data) => {
 519                 tcx.lift(data).map(ty::PredicateAtom::RegionOutlives)
 520             }
 521             ty::PredicateAtom::TypeOutlives(ref data) => {
 522                 tcx.lift(data).map(ty::PredicateAtom::TypeOutlives)
 523             }
 524             ty::PredicateAtom::Projection(ref data) => {
 525                 tcx.lift(data).map(ty::PredicateAtom::Projection)
 526             }
 527             ty::PredicateAtom::WellFormed(ty) => tcx.lift(&ty).map(ty::PredicateAtom::WellFormed),
 528             ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => {
 529                 tcx.lift(&closure_substs).map(|closure_substs| {
 530                     ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind)
 531                 })
 532             }
 533             ty::PredicateAtom::ObjectSafe(trait_def_id) => {
 534                 Some(ty::PredicateAtom::ObjectSafe(trait_def_id))
 535             }
 536             ty::PredicateAtom::ConstEvaluatable(def_id, substs) => {
 537                 tcx.lift(&substs).map(|substs| ty::PredicateAtom::ConstEvaluatable(def_id, substs))
 538             }
 539             ty::PredicateAtom::ConstEquate(c1, c2) => {
 540                 tcx.lift(&(c1, c2)).map(|(c1, c2)| ty::PredicateAtom::ConstEquate(c1, c2))
 541             }
 542             ty::PredicateAtom::TypeWellFormedFromEnv(ty) => {
 543                 tcx.lift(&ty).map(ty::PredicateAtom::TypeWellFormedFromEnv)
 544             }
 545         }
 546     }
 547 }
 548
 549 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> {
 550     type Lifted = ty::Binder<T::Lifted>;
 551     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 552         tcx.lift(self.as_ref().skip_binder()).map(ty::Binder::bind)
 553     }
 554 }
 555
 556 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 557     type Lifted = ty::ParamEnv<'tcx>;
 558     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 559         tcx.lift(&self.caller_bounds())
 560             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
 561     }
 562 }
 563
 564 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 565     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 566     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 567         tcx.lift(&self.param_env).and_then(|param_env| {
 568             tcx.lift(&self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 569         })
 570     }
 571 }
 572
 573 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 574     type Lifted = ty::ClosureSubsts<'tcx>;
 575     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 576         tcx.lift(&self.substs).map(|substs| ty::ClosureSubsts { substs })
 577     }
 578 }
 579
 580 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 581     type Lifted = ty::GeneratorSubsts<'tcx>;
 582     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 583         tcx.lift(&self.substs).map(|substs| ty::GeneratorSubsts { substs })
 584     }
 585 }
 586
 587 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 588     type Lifted = ty::adjustment::Adjustment<'tcx>;
 589     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 590         tcx.lift(&self.kind).and_then(|kind| {
 591             tcx.lift(&self.target).map(|target| ty::adjustment::Adjustment { kind, target })
 592         })
 593     }
 594 }
 595
 596 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 597     type Lifted = ty::adjustment::Adjust<'tcx>;
 598     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 599         match *self {
 600             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 601             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 602             ty::adjustment::Adjust::Deref(ref overloaded) => {
 603                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 604             }
 605             ty::adjustment::Adjust::Borrow(ref autoref) => {
 606                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 607             }
 608         }
 609     }
 610 }
 611
 612 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 613     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 614     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 615         tcx.lift(&self.region).map(|region| ty::adjustment::OverloadedDeref {
 616             region,
 617             mutbl: self.mutbl,
 618             span: self.span,
 619         })
 620     }
 621 }
 622
 623 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 624     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 625     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 626         match *self {
 627             ty::adjustment::AutoBorrow::Ref(r, m) => {
 628                 tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 629             }
 630             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 631         }
 632     }
 633 }
 634
 635 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 636     type Lifted = ty::GenSig<'tcx>;
 637     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 638         tcx.lift(&(self.resume_ty, self.yield_ty, self.return_ty))
 639             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 640     }
 641 }
 642
 643 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 644     type Lifted = ty::FnSig<'tcx>;
 645     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 646         tcx.lift(&self.inputs_and_output).map(|x| ty::FnSig {
 647             inputs_and_output: x,
 648             c_variadic: self.c_variadic,
 649             unsafety: self.unsafety,
 650             abi: self.abi,
 651         })
 652     }
 653 }
 654
 655 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 656     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 657     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 658         tcx.lift(&self.expected).and_then(|expected| {
 659             tcx.lift(&self.found).map(|found| ty::error::ExpectedFound { expected, found })
 660         })
 661     }
 662 }
 663
 664 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 665     type Lifted = ty::error::TypeError<'tcx>;
 666     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 667         use crate::ty::error::TypeError::*;
 668
 669         Some(match *self {
 670             Mismatch => Mismatch,
 671             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 672             AbiMismatch(x) => AbiMismatch(x),
 673             Mutability => Mutability,
 674             TupleSize(x) => TupleSize(x),
 675             FixedArraySize(x) => FixedArraySize(x),
 676             ArgCount => ArgCount,
 677             RegionsDoesNotOutlive(a, b) => {
 678                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 679             }
 680             RegionsInsufficientlyPolymorphic(a, b) => {
 681                 return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 682             }
 683             RegionsOverlyPolymorphic(a, b) => {
 684                 return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b));
 685             }
 686             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 687             IntMismatch(x) => IntMismatch(x),
 688             FloatMismatch(x) => FloatMismatch(x),
 689             Traits(x) => Traits(x),
 690             VariadicMismatch(x) => VariadicMismatch(x),
 691             CyclicTy(t) => return tcx.lift(&t).map(|t| CyclicTy(t)),
 692             CyclicConst(ct) => return tcx.lift(&ct).map(|ct| CyclicConst(ct)),
 693             ProjectionMismatched(x) => ProjectionMismatched(x),
 694             Sorts(ref x) => return tcx.lift(x).map(Sorts),
 695             ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch),
 696             ConstMismatch(ref x) => return tcx.lift(x).map(ConstMismatch),
 697             IntrinsicCast => IntrinsicCast,
 698             TargetFeatureCast(ref x) => TargetFeatureCast(*x),
 699             ObjectUnsafeCoercion(ref x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 700         })
 701     }
 702 }
 703
 704 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 705     type Lifted = ty::InstanceDef<'tcx>;
 706     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 707         match *self {
 708             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 709             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 710             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 711             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 712             ty::InstanceDef::FnPtrShim(def_id, ref ty) => {
 713                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 714             }
 715             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 716             ty::InstanceDef::ClosureOnceShim { call_once } => {
 717                 Some(ty::InstanceDef::ClosureOnceShim { call_once })
 718             }
 719             ty::InstanceDef::DropGlue(def_id, ref ty) => {
 720                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 721             }
 722             ty::InstanceDef::CloneShim(def_id, ref ty) => {
 723                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 724             }
 725         }
 726     }
 727 }
 728
 729 ///////////////////////////////////////////////////////////////////////////
 730 // TypeFoldable implementations.
 731 //
 732 // Ideally, each type should invoke `folder.fold_foo(self)` and
 733 // nothing else. In some cases, though, we haven't gotten around to
 734 // adding methods on the `folder` yet, and thus the folding is
 735 // hard-coded here. This is less-flexible, because folders cannot
 736 // override the behavior, but there are a lot of random types and one
 737 // can easily refactor the folding into the TypeFolder trait as
 738 // needed.
 739
 740 /// AdtDefs are basically the same as a DefId.
 741 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 742     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
 743         *self
 744     }
 745
 746     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
 747         false
 748     }
 749 }
 750
 751 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 752     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (T, U) {
 753         (self.0.fold_with(folder), self.1.fold_with(folder))
 754     }
 755
 756     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 757         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 758     }
 759 }
 760
 761 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 762     for (A, B, C)
 763 {
 764     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (A, B, C) {
 765         (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
 766     }
 767
 768     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 769         self.0.visit_with(visitor) || self.1.visit_with(visitor) || self.2.visit_with(visitor)
 770     }
 771 }
 772
 773 EnumTypeFoldableImpl! {
 774     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 775         (Some)(a),
 776         (None),
 777     } where T: TypeFoldable<'tcx>
 778 }
 779
 780 EnumTypeFoldableImpl! {
 781     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 782         (Ok)(a),
 783         (Err)(a),
 784     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 785 }
 786
 787 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 788     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 789         Rc::new((**self).fold_with(folder))
 790     }
 791
 792     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 793         (**self).visit_with(visitor)
 794     }
 795 }
 796
 797 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 798     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 799         Arc::new((**self).fold_with(folder))
 800     }
 801
 802     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 803         (**self).visit_with(visitor)
 804     }
 805 }
 806
 807 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 808     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 809         let content: T = (**self).fold_with(folder);
 810         box content
 811     }
 812
 813     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 814         (**self).visit_with(visitor)
 815     }
 816 }
 817
 818 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 819     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 820         self.iter().map(|t| t.fold_with(folder)).collect()
 821     }
 822
 823     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 824         self.iter().any(|t| t.visit_with(visitor))
 825     }
 826 }
 827
 828 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 829     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 830         self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>().into_boxed_slice()
 831     }
 832
 833     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 834         self.iter().any(|t| t.visit_with(visitor))
 835     }
 836 }
 837
 838 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
 839     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 840         self.map_bound_ref(|ty| ty.fold_with(folder))
 841     }
 842
 843     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 844         folder.fold_binder(self)
 845     }
 846
 847     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 848         self.as_ref().skip_binder().visit_with(visitor)
 849     }
 850
 851     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 852         visitor.visit_binder(self)
 853     }
 854 }
 855
 856 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> {
 857     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 858         fold_list(*self, folder, |tcx, v| tcx.intern_existential_predicates(v))
 859     }
 860
 861     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 862         self.iter().any(|p| p.visit_with(visitor))
 863     }
 864 }
 865
 866 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 867     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 868         fold_list(*self, folder, |tcx, v| tcx.intern_type_list(v))
 869     }
 870
 871     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 872         self.iter().any(|t| t.visit_with(visitor))
 873     }
 874 }
 875
 876 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 877     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 878         fold_list(*self, folder, |tcx, v| tcx.intern_projs(v))
 879     }
 880
 881     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 882         self.iter().any(|t| t.visit_with(visitor))
 883     }
 884 }
 885
 886 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 887     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 888         use crate::ty::InstanceDef::*;
 889         Self {
 890             substs: self.substs.fold_with(folder),
 891             def: match self.def {
 892                 Item(def) => Item(def.fold_with(folder)),
 893                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 894                 ReifyShim(did) => ReifyShim(did.fold_with(folder)),
 895                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 896                 FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)),
 897                 Virtual(did, i) => Virtual(did.fold_with(folder), i),
 898                 ClosureOnceShim { call_once } => {
 899                     ClosureOnceShim { call_once: call_once.fold_with(folder) }
 900                 }
 901                 DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)),
 902                 CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)),
 903             },
 904         }
 905     }
 906
 907     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 908         use crate::ty::InstanceDef::*;
 909         self.substs.visit_with(visitor)
 910             || match self.def {
 911                 Item(def) => def.visit_with(visitor),
 912                 VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 913                     did.visit_with(visitor)
 914                 }
 915                 FnPtrShim(did, ty) | CloneShim(did, ty) => {
 916                     did.visit_with(visitor) || ty.visit_with(visitor)
 917                 }
 918                 DropGlue(did, ty) => did.visit_with(visitor) || ty.visit_with(visitor),
 919                 ClosureOnceShim { call_once } => call_once.visit_with(visitor),
 920             }
 921     }
 922 }
 923
 924 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 925     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 926         Self { instance: self.instance.fold_with(folder), promoted: self.promoted }
 927     }
 928
 929     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 930         self.instance.visit_with(visitor)
 931     }
 932 }
 933
 934 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 935     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 936         let kind = match self.kind() {
 937             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 938             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
 939             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
 940             ty::Adt(tid, substs) => ty::Adt(*tid, substs.fold_with(folder)),
 941             ty::Dynamic(ref trait_ty, ref region) => {
 942                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder))
 943             }
 944             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
 945             ty::FnDef(def_id, substs) => ty::FnDef(*def_id, substs.fold_with(folder)),
 946             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
 947             ty::Ref(ref r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), *mutbl),
 948             ty::Generator(did, substs, movability) => {
 949                 ty::Generator(*did, substs.fold_with(folder), *movability)
 950             }
 951             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
 952             ty::Closure(did, substs) => ty::Closure(*did, substs.fold_with(folder)),
 953             ty::Projection(ref data) => ty::Projection(data.fold_with(folder)),
 954             ty::Opaque(did, substs) => ty::Opaque(*did, substs.fold_with(folder)),
 955
 956             ty::Bool
 957             | ty::Char
 958             | ty::Str
 959             | ty::Int(_)
 960             | ty::Uint(_)
 961             | ty::Float(_)
 962             | ty::Error(_)
 963             | ty::Infer(_)
 964             | ty::Param(..)
 965             | ty::Bound(..)
 966             | ty::Placeholder(..)
 967             | ty::Never
 968             | ty::Foreign(..) => return self,
 969         };
 970
 971         if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) }
 972     }
 973
 974     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 975         folder.fold_ty(*self)
 976     }
 977
 978     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 979         match self.kind() {
 980             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 981             ty::Array(typ, sz) => typ.visit_with(visitor) || sz.visit_with(visitor),
 982             ty::Slice(typ) => typ.visit_with(visitor),
 983             ty::Adt(_, substs) => substs.visit_with(visitor),
 984             ty::Dynamic(ref trait_ty, ref reg) => {
 985                 trait_ty.visit_with(visitor) || reg.visit_with(visitor)
 986             }
 987             ty::Tuple(ts) => ts.visit_with(visitor),
 988             ty::FnDef(_, substs) => substs.visit_with(visitor),
 989             ty::FnPtr(ref f) => f.visit_with(visitor),
 990             ty::Ref(r, ty, _) => r.visit_with(visitor) || ty.visit_with(visitor),
 991             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 992             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 993             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 994             ty::Projection(ref data) => data.visit_with(visitor),
 995             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 996
 997             ty::Bool
 998             | ty::Char
 999             | ty::Str
1000             | ty::Int(_)
1001             | ty::Uint(_)
1002             | ty::Float(_)
1003             | ty::Error(_)
1004             | ty::Infer(_)
1005             | ty::Bound(..)
1006             | ty::Placeholder(..)
1007             | ty::Param(..)
1008             | ty::Never
1009             | ty::Foreign(..) => false,
1010         }
1011     }
1012
1013     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1014         visitor.visit_ty(self)
1015     }
1016 }
1017
1018 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1019     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
1020         *self
1021     }
1022
1023     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1024         folder.fold_region(*self)
1025     }
1026
1027     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1028         false
1029     }
1030
1031     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1032         visitor.visit_region(*self)
1033     }
1034 }
1035
1036 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1037     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1038         let new = ty::PredicateKind::super_fold_with(&self.inner.kind, folder);
1039         folder.tcx().reuse_or_mk_predicate(*self, new)
1040     }
1041
1042     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1043         ty::PredicateKind::super_visit_with(&self.inner.kind, visitor)
1044     }
1045
1046     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1047         visitor.visit_predicate(*self)
1048     }
1049
1050     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1051         self.inner.outer_exclusive_binder > binder
1052     }
1053
1054     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1055         self.inner.flags.intersects(flags)
1056     }
1057 }
1058
1059 pub(super) trait PredicateVisitor<'tcx>: TypeVisitor<'tcx> {
1060     fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool;
1061 }
1062
1063 impl<T: TypeVisitor<'tcx>> PredicateVisitor<'tcx> for T {
1064     default fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool {
1065         predicate.super_visit_with(self)
1066     }
1067 }
1068
1069 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1070     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1071         fold_list(*self, folder, |tcx, v| tcx.intern_predicates(v))
1072     }
1073
1074     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1075         self.iter().any(|p| p.visit_with(visitor))
1076     }
1077 }
1078
1079 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1080     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1081         self.iter().map(|x| x.fold_with(folder)).collect()
1082     }
1083
1084     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1085         self.iter().any(|t| t.visit_with(visitor))
1086     }
1087 }
1088
1089 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1090     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1091         let ty = self.ty.fold_with(folder);
1092         let val = self.val.fold_with(folder);
1093         if ty != self.ty || val != self.val {
1094             folder.tcx().mk_const(ty::Const { ty, val })
1095         } else {
1096             *self
1097         }
1098     }
1099
1100     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1101         folder.fold_const(*self)
1102     }
1103
1104     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1105         self.ty.visit_with(visitor) || self.val.visit_with(visitor)
1106     }
1107
1108     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1109         visitor.visit_const(self)
1110     }
1111 }
1112
1113 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1114     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1115         match *self {
1116             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
1117             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
1118             ty::ConstKind::Unevaluated(did, substs, promoted) => {
1119                 ty::ConstKind::Unevaluated(did, substs.fold_with(folder), promoted)
1120             }
1121             ty::ConstKind::Value(_)
1122             | ty::ConstKind::Bound(..)
1123             | ty::ConstKind::Placeholder(..)
1124             | ty::ConstKind::Error(_) => *self,
1125         }
1126     }
1127
1128     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1129         match *self {
1130             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1131             ty::ConstKind::Param(p) => p.visit_with(visitor),
1132             ty::ConstKind::Unevaluated(_, substs, _) => substs.visit_with(visitor),
1133             ty::ConstKind::Value(_)
1134             | ty::ConstKind::Bound(..)
1135             | ty::ConstKind::Placeholder(_)
1136             | ty::ConstKind::Error(_) => false,
1137         }
1138     }
1139 }
1140
1141 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1142     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
1143         *self
1144     }
1145
1146     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1147         false
1148     }
1149 }
1150
1151 // Does the equivalent of
1152 // ```
1153 // let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
1154 // folder.tcx().intern_*(&v)
1155 // ```
1156 fn fold_list<'tcx, F, T>(
1157     list: &'tcx ty::List<T>,
1158     folder: &mut F,
1159     intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>,
1160 ) -> &'tcx ty::List<T>
1161 where
1162     F: TypeFolder<'tcx>,
1163     T: TypeFoldable<'tcx> + PartialEq + Copy,
1164 {
1165     let mut iter = list.iter();
1166     // Look for the first element that changed
1167     if let Some((i, new_t)) = iter.by_ref().enumerate().find_map(|(i, t)| {
1168         let new_t = t.fold_with(folder);
1169         if new_t == t { None } else { Some((i, new_t)) }
1170     }) {
1171         // An element changed, prepare to intern the resulting list
1172         let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len());
1173         new_list.extend_from_slice(&list[..i]);
1174         new_list.push(new_t);
1175         new_list.extend(iter.map(|t| t.fold_with(folder)));
1176         intern(folder.tcx(), &new_list)
1177     } else {
1178         list
1179     }
1180 }