src/librustc_middle/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::{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             FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.def_id, &[])?;
  24             Ok(())
  25         })
  26     }
  27 }
  28
  29 impl fmt::Debug for ty::AdtDef {
  30     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  31         ty::tls::with(|tcx| {
  32             FmtPrinter::new(tcx, f, Namespace::TypeNS).print_def_path(self.did, &[])?;
  33             Ok(())
  34         })
  35     }
  36 }
  37
  38 impl fmt::Debug for ty::UpvarId {
  39     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  40         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  41         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  42     }
  43 }
  44
  45 impl fmt::Debug for ty::UpvarBorrow<'tcx> {
  46     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  47         write!(f, "UpvarBorrow({:?}, {:?})", self.kind, self.region)
  48     }
  49 }
  50
  51 impl fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  52     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  53         fmt::Display::fmt(self, f)
  54     }
  55 }
  56
  57 impl fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  58     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  59         write!(f, "{:?} -> {}", self.kind, self.target)
  60     }
  61 }
  62
  63 impl fmt::Debug for ty::BoundRegion {
  64     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  65         match *self {
  66             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  67             ty::BrNamed(did, name) => {
  68                 if did.index == CRATE_DEF_INDEX {
  69                     write!(f, "BrNamed({})", name)
  70                 } else {
  71                     write!(f, "BrNamed({:?}, {})", did, name)
  72                 }
  73             }
  74             ty::BrEnv => write!(f, "BrEnv"),
  75         }
  76     }
  77 }
  78
  79 impl fmt::Debug for ty::RegionKind {
  80     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  81         match *self {
  82             ty::ReEarlyBound(ref data) => write!(f, "ReEarlyBound({}, {})", data.index, data.name),
  83
  84             ty::ReLateBound(binder_id, ref bound_region) => {
  85                 write!(f, "ReLateBound({:?}, {:?})", binder_id, bound_region)
  86             }
  87
  88             ty::ReFree(ref fr) => fr.fmt(f),
  89
  90             ty::ReStatic => write!(f, "ReStatic"),
  91
  92             ty::ReVar(ref vid) => vid.fmt(f),
  93
  94             ty::RePlaceholder(placeholder) => write!(f, "RePlaceholder({:?})", placeholder),
  95
  96             ty::ReEmpty(ui) => write!(f, "ReEmpty({:?})", ui),
  97
  98             ty::ReErased => write!(f, "ReErased"),
  99         }
 100     }
 101 }
 102
 103 impl fmt::Debug for ty::FreeRegion {
 104     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 105         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
 106     }
 107 }
 108
 109 impl fmt::Debug for ty::Variance {
 110     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 111         f.write_str(match *self {
 112             ty::Covariant => "+",
 113             ty::Contravariant => "-",
 114             ty::Invariant => "o",
 115             ty::Bivariant => "*",
 116         })
 117     }
 118 }
 119
 120 impl fmt::Debug for ty::FnSig<'tcx> {
 121     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 122         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
 123     }
 124 }
 125
 126 impl fmt::Debug for ty::TyVid {
 127     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 128         write!(f, "_#{}t", self.index)
 129     }
 130 }
 131
 132 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
 133     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 134         write!(f, "_#{}c", self.index)
 135     }
 136 }
 137
 138 impl fmt::Debug for ty::IntVid {
 139     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 140         write!(f, "_#{}i", self.index)
 141     }
 142 }
 143
 144 impl fmt::Debug for ty::FloatVid {
 145     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 146         write!(f, "_#{}f", self.index)
 147     }
 148 }
 149
 150 impl fmt::Debug for ty::RegionVid {
 151     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 152         write!(f, "'_#{}r", self.index())
 153     }
 154 }
 155
 156 impl fmt::Debug for ty::InferTy {
 157     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 158         match *self {
 159             ty::TyVar(ref v) => v.fmt(f),
 160             ty::IntVar(ref v) => v.fmt(f),
 161             ty::FloatVar(ref v) => v.fmt(f),
 162             ty::FreshTy(v) => write!(f, "FreshTy({:?})", v),
 163             ty::FreshIntTy(v) => write!(f, "FreshIntTy({:?})", v),
 164             ty::FreshFloatTy(v) => write!(f, "FreshFloatTy({:?})", v),
 165         }
 166     }
 167 }
 168
 169 impl fmt::Debug for ty::IntVarValue {
 170     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 171         match *self {
 172             ty::IntType(ref v) => v.fmt(f),
 173             ty::UintType(ref v) => v.fmt(f),
 174         }
 175     }
 176 }
 177
 178 impl fmt::Debug for ty::FloatVarValue {
 179     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 180         self.0.fmt(f)
 181     }
 182 }
 183
 184 impl fmt::Debug for ty::TraitRef<'tcx> {
 185     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 186         fmt::Display::fmt(self, f)
 187     }
 188 }
 189
 190 impl fmt::Debug for Ty<'tcx> {
 191     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 192         fmt::Display::fmt(self, f)
 193     }
 194 }
 195
 196 impl fmt::Debug for ty::ParamTy {
 197     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 198         write!(f, "{}/#{}", self.name, self.index)
 199     }
 200 }
 201
 202 impl fmt::Debug for ty::ParamConst {
 203     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 204         write!(f, "{}/#{}", self.name, self.index)
 205     }
 206 }
 207
 208 impl fmt::Debug for ty::TraitPredicate<'tcx> {
 209     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 210         write!(f, "TraitPredicate({:?})", self.trait_ref)
 211     }
 212 }
 213
 214 impl fmt::Debug for ty::ProjectionPredicate<'tcx> {
 215     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 216         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.ty)
 217     }
 218 }
 219
 220 impl fmt::Debug for ty::Predicate<'tcx> {
 221     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 222         write!(f, "{:?}", self.kind())
 223     }
 224 }
 225
 226 impl fmt::Debug for ty::PredicateKind<'tcx> {
 227     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 228         match *self {
 229             ty::PredicateKind::ForAll(binder) => write!(f, "ForAll({:?})", binder),
 230             ty::PredicateKind::Atom(atom) => write!(f, "{:?}", atom),
 231         }
 232     }
 233 }
 234
 235 impl fmt::Debug for ty::PredicateAtom<'tcx> {
 236     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 237         match *self {
 238             ty::PredicateAtom::Trait(ref a, constness) => {
 239                 if let hir::Constness::Const = constness {
 240                     write!(f, "const ")?;
 241                 }
 242                 a.fmt(f)
 243             }
 244             ty::PredicateAtom::Subtype(ref pair) => pair.fmt(f),
 245             ty::PredicateAtom::RegionOutlives(ref pair) => pair.fmt(f),
 246             ty::PredicateAtom::TypeOutlives(ref pair) => pair.fmt(f),
 247             ty::PredicateAtom::Projection(ref pair) => pair.fmt(f),
 248             ty::PredicateAtom::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 249             ty::PredicateAtom::ObjectSafe(trait_def_id) => {
 250                 write!(f, "ObjectSafe({:?})", trait_def_id)
 251             }
 252             ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => {
 253                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 254             }
 255             ty::PredicateAtom::ConstEvaluatable(def_id, substs) => {
 256                 write!(f, "ConstEvaluatable({:?}, {:?})", def_id, substs)
 257             }
 258             ty::PredicateAtom::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 259         }
 260     }
 261 }
 262
 263 ///////////////////////////////////////////////////////////////////////////
 264 // Atomic structs
 265 //
 266 // For things that don't carry any arena-allocated data (and are
 267 // copy...), just add them to this list.
 268
 269 CloneTypeFoldableAndLiftImpls! {
 270     (),
 271     bool,
 272     usize,
 273     ::rustc_target::abi::VariantIdx,
 274     u64,
 275     String,
 276     crate::middle::region::Scope,
 277     ::rustc_ast::ast::FloatTy,
 278     ::rustc_ast::ast::InlineAsmOptions,
 279     ::rustc_ast::ast::InlineAsmTemplatePiece,
 280     ::rustc_ast::ast::NodeId,
 281     ::rustc_span::symbol::Symbol,
 282     ::rustc_hir::def::Res,
 283     ::rustc_hir::def_id::DefId,
 284     ::rustc_hir::def_id::LocalDefId,
 285     ::rustc_hir::LlvmInlineAsmInner,
 286     ::rustc_hir::MatchSource,
 287     ::rustc_hir::Mutability,
 288     ::rustc_hir::Unsafety,
 289     ::rustc_target::asm::InlineAsmRegOrRegClass,
 290     ::rustc_target::spec::abi::Abi,
 291     crate::mir::Local,
 292     crate::mir::Promoted,
 293     crate::traits::Reveal,
 294     crate::ty::adjustment::AutoBorrowMutability,
 295     crate::ty::AdtKind,
 296     // Including `BoundRegion` is a *bit* dubious, but direct
 297     // references to bound region appear in `ty::Error`, and aren't
 298     // really meant to be folded. In general, we can only fold a fully
 299     // general `Region`.
 300     crate::ty::BoundRegion,
 301     crate::ty::Placeholder<crate::ty::BoundRegion>,
 302     crate::ty::ClosureKind,
 303     crate::ty::FreeRegion,
 304     crate::ty::InferTy,
 305     crate::ty::IntVarValue,
 306     crate::ty::ParamConst,
 307     crate::ty::ParamTy,
 308     crate::ty::adjustment::PointerCast,
 309     crate::ty::RegionVid,
 310     crate::ty::UniverseIndex,
 311     crate::ty::Variance,
 312     ::rustc_span::Span,
 313 }
 314
 315 ///////////////////////////////////////////////////////////////////////////
 316 // Lift implementations
 317
 318 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 319 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 320     type Lifted = (A::Lifted, B::Lifted);
 321     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 322         tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b)))
 323     }
 324 }
 325
 326 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 327     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 328     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 329         tcx.lift(&self.0)
 330             .and_then(|a| tcx.lift(&self.1).and_then(|b| tcx.lift(&self.2).map(|c| (a, b, c))))
 331     }
 332 }
 333
 334 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 335     type Lifted = Option<T::Lifted>;
 336     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 337         match *self {
 338             Some(ref x) => tcx.lift(x).map(Some),
 339             None => Some(None),
 340         }
 341     }
 342 }
 343
 344 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 345     type Lifted = Result<T::Lifted, E::Lifted>;
 346     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 347         match *self {
 348             Ok(ref x) => tcx.lift(x).map(Ok),
 349             Err(ref e) => tcx.lift(e).map(Err),
 350         }
 351     }
 352 }
 353
 354 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 355     type Lifted = Box<T::Lifted>;
 356     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 357         tcx.lift(&**self).map(Box::new)
 358     }
 359 }
 360
 361 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Rc<T> {
 362     type Lifted = Rc<T::Lifted>;
 363     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 364         tcx.lift(&**self).map(Rc::new)
 365     }
 366 }
 367
 368 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Arc<T> {
 369     type Lifted = Arc<T::Lifted>;
 370     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 371         tcx.lift(&**self).map(Arc::new)
 372     }
 373 }
 374
 375 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] {
 376     type Lifted = Vec<T::Lifted>;
 377     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 378         // type annotation needed to inform `projection_must_outlive`
 379         let mut result: Vec<<T as Lift<'tcx>>::Lifted> = Vec::with_capacity(self.len());
 380         for x in self {
 381             if let Some(value) = tcx.lift(x) {
 382                 result.push(value);
 383             } else {
 384                 return None;
 385             }
 386         }
 387         Some(result)
 388     }
 389 }
 390
 391 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 392     type Lifted = Vec<T::Lifted>;
 393     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 394         tcx.lift(&self[..])
 395     }
 396 }
 397
 398 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 399     type Lifted = IndexVec<I, T::Lifted>;
 400     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 401         self.iter().map(|e| tcx.lift(e)).collect()
 402     }
 403 }
 404
 405 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
 406     type Lifted = ty::TraitRef<'tcx>;
 407     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 408         tcx.lift(&self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
 409     }
 410 }
 411
 412 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
 413     type Lifted = ty::ExistentialTraitRef<'tcx>;
 414     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 415         tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
 416     }
 417 }
 418
 419 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 420     type Lifted = ty::ExistentialPredicate<'tcx>;
 421     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 422         match self {
 423             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
 424             ty::ExistentialPredicate::Projection(x) => {
 425                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
 426             }
 427             ty::ExistentialPredicate::AutoTrait(def_id) => {
 428                 Some(ty::ExistentialPredicate::AutoTrait(*def_id))
 429             }
 430         }
 431     }
 432 }
 433
 434 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
 435     type Lifted = ty::TraitPredicate<'tcx>;
 436     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
 437         tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref })
 438     }
 439 }
 440
 441 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 442     type Lifted = ty::SubtypePredicate<'tcx>;
 443     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
 444         tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 445             a_is_expected: self.a_is_expected,
 446             a,
 447             b,
 448         })
 449     }
 450 }
 451
 452 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 453     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 454     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 455         tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 456     }
 457 }
 458
 459 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 460     type Lifted = ty::ProjectionTy<'tcx>;
 461     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
 462         tcx.lift(&self.substs)
 463             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
 464     }
 465 }
 466
 467 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 468     type Lifted = ty::ProjectionPredicate<'tcx>;
 469     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
 470         tcx.lift(&(self.projection_ty, self.ty))
 471             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
 472     }
 473 }
 474
 475 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 476     type Lifted = ty::ExistentialProjection<'tcx>;
 477     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 478         tcx.lift(&self.substs).map(|substs| ty::ExistentialProjection {
 479             substs,
 480             ty: tcx.lift(&self.ty).expect("type must lift when substs do"),
 481             item_def_id: self.item_def_id,
 482         })
 483     }
 484 }
 485
 486 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 487     type Lifted = ty::PredicateKind<'tcx>;
 488     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 489         match *self {
 490             ty::PredicateKind::ForAll(ref binder) => {
 491                 tcx.lift(binder).map(ty::PredicateKind::ForAll)
 492             }
 493             ty::PredicateKind::Atom(ref atom) => tcx.lift(atom).map(ty::PredicateKind::Atom),
 494         }
 495     }
 496 }
 497
 498 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> {
 499     type Lifted = ty::PredicateAtom<'tcx>;
 500     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 501         match *self {
 502             ty::PredicateAtom::Trait(ref data, constness) => {
 503                 tcx.lift(data).map(|data| ty::PredicateAtom::Trait(data, constness))
 504             }
 505             ty::PredicateAtom::Subtype(ref data) => tcx.lift(data).map(ty::PredicateAtom::Subtype),
 506             ty::PredicateAtom::RegionOutlives(ref data) => {
 507                 tcx.lift(data).map(ty::PredicateAtom::RegionOutlives)
 508             }
 509             ty::PredicateAtom::TypeOutlives(ref data) => {
 510                 tcx.lift(data).map(ty::PredicateAtom::TypeOutlives)
 511             }
 512             ty::PredicateAtom::Projection(ref data) => {
 513                 tcx.lift(data).map(ty::PredicateAtom::Projection)
 514             }
 515             ty::PredicateAtom::WellFormed(ty) => tcx.lift(&ty).map(ty::PredicateAtom::WellFormed),
 516             ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => {
 517                 tcx.lift(&closure_substs).map(|closure_substs| {
 518                     ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind)
 519                 })
 520             }
 521             ty::PredicateAtom::ObjectSafe(trait_def_id) => {
 522                 Some(ty::PredicateAtom::ObjectSafe(trait_def_id))
 523             }
 524             ty::PredicateAtom::ConstEvaluatable(def_id, substs) => {
 525                 tcx.lift(&substs).map(|substs| ty::PredicateAtom::ConstEvaluatable(def_id, substs))
 526             }
 527             ty::PredicateAtom::ConstEquate(c1, c2) => {
 528                 tcx.lift(&(c1, c2)).map(|(c1, c2)| ty::PredicateAtom::ConstEquate(c1, c2))
 529             }
 530         }
 531     }
 532 }
 533
 534 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> {
 535     type Lifted = ty::Binder<T::Lifted>;
 536     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 537         tcx.lift(self.as_ref().skip_binder()).map(ty::Binder::bind)
 538     }
 539 }
 540
 541 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 542     type Lifted = ty::ParamEnv<'tcx>;
 543     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 544         tcx.lift(&self.caller_bounds())
 545             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.def_id))
 546     }
 547 }
 548
 549 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
 550     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
 551     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 552         tcx.lift(&self.param_env).and_then(|param_env| {
 553             tcx.lift(&self.value).map(|value| ty::ParamEnvAnd { param_env, value })
 554         })
 555     }
 556 }
 557
 558 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 559     type Lifted = ty::ClosureSubsts<'tcx>;
 560     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 561         tcx.lift(&self.substs).map(|substs| ty::ClosureSubsts { substs })
 562     }
 563 }
 564
 565 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
 566     type Lifted = ty::GeneratorSubsts<'tcx>;
 567     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 568         tcx.lift(&self.substs).map(|substs| ty::GeneratorSubsts { substs })
 569     }
 570 }
 571
 572 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
 573     type Lifted = ty::adjustment::Adjustment<'tcx>;
 574     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 575         tcx.lift(&self.kind).and_then(|kind| {
 576             tcx.lift(&self.target).map(|target| ty::adjustment::Adjustment { kind, target })
 577         })
 578     }
 579 }
 580
 581 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 582     type Lifted = ty::adjustment::Adjust<'tcx>;
 583     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 584         match *self {
 585             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
 586             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
 587             ty::adjustment::Adjust::Deref(ref overloaded) => {
 588                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
 589             }
 590             ty::adjustment::Adjust::Borrow(ref autoref) => {
 591                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
 592             }
 593         }
 594     }
 595 }
 596
 597 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 598     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
 599     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 600         tcx.lift(&self.region)
 601             .map(|region| ty::adjustment::OverloadedDeref { region, mutbl: self.mutbl })
 602     }
 603 }
 604
 605 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 606     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 607     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 608         match *self {
 609             ty::adjustment::AutoBorrow::Ref(r, m) => {
 610                 tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 611             }
 612             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
 613         }
 614     }
 615 }
 616
 617 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
 618     type Lifted = ty::GenSig<'tcx>;
 619     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 620         tcx.lift(&(self.resume_ty, self.yield_ty, self.return_ty))
 621             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
 622     }
 623 }
 624
 625 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 626     type Lifted = ty::FnSig<'tcx>;
 627     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 628         tcx.lift(&self.inputs_and_output).map(|x| ty::FnSig {
 629             inputs_and_output: x,
 630             c_variadic: self.c_variadic,
 631             unsafety: self.unsafety,
 632             abi: self.abi,
 633         })
 634     }
 635 }
 636
 637 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 638     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 639     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 640         tcx.lift(&self.expected).and_then(|expected| {
 641             tcx.lift(&self.found).map(|found| ty::error::ExpectedFound { expected, found })
 642         })
 643     }
 644 }
 645
 646 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 647     type Lifted = ty::error::TypeError<'tcx>;
 648     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 649         use crate::ty::error::TypeError::*;
 650
 651         Some(match *self {
 652             Mismatch => Mismatch,
 653             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 654             AbiMismatch(x) => AbiMismatch(x),
 655             Mutability => Mutability,
 656             TupleSize(x) => TupleSize(x),
 657             FixedArraySize(x) => FixedArraySize(x),
 658             ArgCount => ArgCount,
 659             RegionsDoesNotOutlive(a, b) => {
 660                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
 661             }
 662             RegionsInsufficientlyPolymorphic(a, b) => {
 663                 return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
 664             }
 665             RegionsOverlyPolymorphic(a, b) => {
 666                 return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b));
 667             }
 668             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
 669             IntMismatch(x) => IntMismatch(x),
 670             FloatMismatch(x) => FloatMismatch(x),
 671             Traits(x) => Traits(x),
 672             VariadicMismatch(x) => VariadicMismatch(x),
 673             CyclicTy(t) => return tcx.lift(&t).map(|t| CyclicTy(t)),
 674             ProjectionMismatched(x) => ProjectionMismatched(x),
 675             Sorts(ref x) => return tcx.lift(x).map(Sorts),
 676             ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch),
 677             ConstMismatch(ref x) => return tcx.lift(x).map(ConstMismatch),
 678             IntrinsicCast => IntrinsicCast,
 679             TargetFeatureCast(ref x) => TargetFeatureCast(*x),
 680             ObjectUnsafeCoercion(ref x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
 681         })
 682     }
 683 }
 684
 685 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
 686     type Lifted = ty::InstanceDef<'tcx>;
 687     fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 688         match *self {
 689             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
 690             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
 691             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
 692             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
 693             ty::InstanceDef::FnPtrShim(def_id, ref ty) => {
 694                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
 695             }
 696             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
 697             ty::InstanceDef::ClosureOnceShim { call_once } => {
 698                 Some(ty::InstanceDef::ClosureOnceShim { call_once })
 699             }
 700             ty::InstanceDef::DropGlue(def_id, ref ty) => {
 701                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
 702             }
 703             ty::InstanceDef::CloneShim(def_id, ref ty) => {
 704                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
 705             }
 706         }
 707     }
 708 }
 709
 710 ///////////////////////////////////////////////////////////////////////////
 711 // TypeFoldable implementations.
 712 //
 713 // Ideally, each type should invoke `folder.fold_foo(self)` and
 714 // nothing else. In some cases, though, we haven't gotten around to
 715 // adding methods on the `folder` yet, and thus the folding is
 716 // hard-coded here. This is less-flexible, because folders cannot
 717 // override the behavior, but there are a lot of random types and one
 718 // can easily refactor the folding into the TypeFolder trait as
 719 // needed.
 720
 721 /// AdtDefs are basically the same as a DefId.
 722 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::AdtDef {
 723     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
 724         *self
 725     }
 726
 727     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
 728         false
 729     }
 730 }
 731
 732 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 733     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (T, U) {
 734         (self.0.fold_with(folder), self.1.fold_with(folder))
 735     }
 736
 737     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 738         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 739     }
 740 }
 741
 742 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 743     for (A, B, C)
 744 {
 745     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> (A, B, C) {
 746         (self.0.fold_with(folder), self.1.fold_with(folder), self.2.fold_with(folder))
 747     }
 748
 749     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 750         self.0.visit_with(visitor) || self.1.visit_with(visitor) || self.2.visit_with(visitor)
 751     }
 752 }
 753
 754 EnumTypeFoldableImpl! {
 755     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 756         (Some)(a),
 757         (None),
 758     } where T: TypeFoldable<'tcx>
 759 }
 760
 761 EnumTypeFoldableImpl! {
 762     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 763         (Ok)(a),
 764         (Err)(a),
 765     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 766 }
 767
 768 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 769     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 770         Rc::new((**self).fold_with(folder))
 771     }
 772
 773     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 774         (**self).visit_with(visitor)
 775     }
 776 }
 777
 778 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 779     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 780         Arc::new((**self).fold_with(folder))
 781     }
 782
 783     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 784         (**self).visit_with(visitor)
 785     }
 786 }
 787
 788 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 789     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 790         let content: T = (**self).fold_with(folder);
 791         box content
 792     }
 793
 794     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 795         (**self).visit_with(visitor)
 796     }
 797 }
 798
 799 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 800     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 801         self.iter().map(|t| t.fold_with(folder)).collect()
 802     }
 803
 804     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 805         self.iter().any(|t| t.visit_with(visitor))
 806     }
 807 }
 808
 809 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 810     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 811         self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>().into_boxed_slice()
 812     }
 813
 814     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 815         self.iter().any(|t| t.visit_with(visitor))
 816     }
 817 }
 818
 819 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
 820     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 821         self.map_bound_ref(|ty| ty.fold_with(folder))
 822     }
 823
 824     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 825         folder.fold_binder(self)
 826     }
 827
 828     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 829         self.as_ref().skip_binder().visit_with(visitor)
 830     }
 831
 832     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 833         visitor.visit_binder(self)
 834     }
 835 }
 836
 837 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::ExistentialPredicate<'tcx>> {
 838     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 839         fold_list(*self, folder, |tcx, v| tcx.intern_existential_predicates(v))
 840     }
 841
 842     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 843         self.iter().any(|p| p.visit_with(visitor))
 844     }
 845 }
 846
 847 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<Ty<'tcx>> {
 848     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 849         fold_list(*self, folder, |tcx, v| tcx.intern_type_list(v))
 850     }
 851
 852     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 853         self.iter().any(|t| t.visit_with(visitor))
 854     }
 855 }
 856
 857 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 858     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 859         fold_list(*self, folder, |tcx, v| tcx.intern_projs(v))
 860     }
 861
 862     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 863         self.iter().any(|t| t.visit_with(visitor))
 864     }
 865 }
 866
 867 impl<'tcx> TypeFoldable<'tcx> for ty::instance::Instance<'tcx> {
 868     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 869         use crate::ty::InstanceDef::*;
 870         Self {
 871             substs: self.substs.fold_with(folder),
 872             def: match self.def {
 873                 Item(def) => Item(def.fold_with(folder)),
 874                 VtableShim(did) => VtableShim(did.fold_with(folder)),
 875                 ReifyShim(did) => ReifyShim(did.fold_with(folder)),
 876                 Intrinsic(did) => Intrinsic(did.fold_with(folder)),
 877                 FnPtrShim(did, ty) => FnPtrShim(did.fold_with(folder), ty.fold_with(folder)),
 878                 Virtual(did, i) => Virtual(did.fold_with(folder), i),
 879                 ClosureOnceShim { call_once } => {
 880                     ClosureOnceShim { call_once: call_once.fold_with(folder) }
 881                 }
 882                 DropGlue(did, ty) => DropGlue(did.fold_with(folder), ty.fold_with(folder)),
 883                 CloneShim(did, ty) => CloneShim(did.fold_with(folder), ty.fold_with(folder)),
 884             },
 885         }
 886     }
 887
 888     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 889         use crate::ty::InstanceDef::*;
 890         self.substs.visit_with(visitor)
 891             || match self.def {
 892                 Item(def) => def.visit_with(visitor),
 893                 VtableShim(did) | ReifyShim(did) | Intrinsic(did) | Virtual(did, _) => {
 894                     did.visit_with(visitor)
 895                 }
 896                 FnPtrShim(did, ty) | CloneShim(did, ty) => {
 897                     did.visit_with(visitor) || ty.visit_with(visitor)
 898                 }
 899                 DropGlue(did, ty) => did.visit_with(visitor) || ty.visit_with(visitor),
 900                 ClosureOnceShim { call_once } => call_once.visit_with(visitor),
 901             }
 902     }
 903 }
 904
 905 impl<'tcx> TypeFoldable<'tcx> for interpret::GlobalId<'tcx> {
 906     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 907         Self { instance: self.instance.fold_with(folder), promoted: self.promoted }
 908     }
 909
 910     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 911         self.instance.visit_with(visitor)
 912     }
 913 }
 914
 915 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 916     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 917         let kind = match self.kind {
 918             ty::RawPtr(tm) => ty::RawPtr(tm.fold_with(folder)),
 919             ty::Array(typ, sz) => ty::Array(typ.fold_with(folder), sz.fold_with(folder)),
 920             ty::Slice(typ) => ty::Slice(typ.fold_with(folder)),
 921             ty::Adt(tid, substs) => ty::Adt(tid, substs.fold_with(folder)),
 922             ty::Dynamic(ref trait_ty, ref region) => {
 923                 ty::Dynamic(trait_ty.fold_with(folder), region.fold_with(folder))
 924             }
 925             ty::Tuple(ts) => ty::Tuple(ts.fold_with(folder)),
 926             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.fold_with(folder)),
 927             ty::FnPtr(f) => ty::FnPtr(f.fold_with(folder)),
 928             ty::Ref(ref r, ty, mutbl) => ty::Ref(r.fold_with(folder), ty.fold_with(folder), mutbl),
 929             ty::Generator(did, substs, movability) => {
 930                 ty::Generator(did, substs.fold_with(folder), movability)
 931             }
 932             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.fold_with(folder)),
 933             ty::Closure(did, substs) => ty::Closure(did, substs.fold_with(folder)),
 934             ty::Projection(ref data) => ty::Projection(data.fold_with(folder)),
 935             ty::Opaque(did, substs) => ty::Opaque(did, substs.fold_with(folder)),
 936
 937             ty::Bool
 938             | ty::Char
 939             | ty::Str
 940             | ty::Int(_)
 941             | ty::Uint(_)
 942             | ty::Float(_)
 943             | ty::Error(_)
 944             | ty::Infer(_)
 945             | ty::Param(..)
 946             | ty::Bound(..)
 947             | ty::Placeholder(..)
 948             | ty::Never
 949             | ty::Foreign(..) => return self,
 950         };
 951
 952         if self.kind == kind { self } else { folder.tcx().mk_ty(kind) }
 953     }
 954
 955     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
 956         folder.fold_ty(*self)
 957     }
 958
 959     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 960         match self.kind {
 961             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 962             ty::Array(typ, sz) => typ.visit_with(visitor) || sz.visit_with(visitor),
 963             ty::Slice(typ) => typ.visit_with(visitor),
 964             ty::Adt(_, substs) => substs.visit_with(visitor),
 965             ty::Dynamic(ref trait_ty, ref reg) => {
 966                 trait_ty.visit_with(visitor) || reg.visit_with(visitor)
 967             }
 968             ty::Tuple(ts) => ts.visit_with(visitor),
 969             ty::FnDef(_, substs) => substs.visit_with(visitor),
 970             ty::FnPtr(ref f) => f.visit_with(visitor),
 971             ty::Ref(r, ty, _) => r.visit_with(visitor) || ty.visit_with(visitor),
 972             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 973             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 974             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 975             ty::Projection(ref data) => data.visit_with(visitor),
 976             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 977
 978             ty::Bool
 979             | ty::Char
 980             | ty::Str
 981             | ty::Int(_)
 982             | ty::Uint(_)
 983             | ty::Float(_)
 984             | ty::Error(_)
 985             | ty::Infer(_)
 986             | ty::Bound(..)
 987             | ty::Placeholder(..)
 988             | ty::Param(..)
 989             | ty::Never
 990             | ty::Foreign(..) => false,
 991         }
 992     }
 993
 994     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 995         visitor.visit_ty(self)
 996     }
 997 }
 998
 999 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
1000     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
1001         *self
1002     }
1003
1004     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1005         folder.fold_region(*self)
1006     }
1007
1008     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1009         false
1010     }
1011
1012     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1013         visitor.visit_region(*self)
1014     }
1015 }
1016
1017 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
1018     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1019         let new = ty::PredicateKind::super_fold_with(&self.inner.kind, folder);
1020         folder.tcx().reuse_or_mk_predicate(*self, new)
1021     }
1022
1023     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1024         ty::PredicateKind::super_visit_with(&self.inner.kind, visitor)
1025     }
1026
1027     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1028         visitor.visit_predicate(*self)
1029     }
1030
1031     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
1032         self.inner.outer_exclusive_binder > binder
1033     }
1034
1035     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
1036         self.inner.flags.intersects(flags)
1037     }
1038 }
1039
1040 pub(super) trait PredicateVisitor<'tcx>: TypeVisitor<'tcx> {
1041     fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool;
1042 }
1043
1044 impl<T: TypeVisitor<'tcx>> PredicateVisitor<'tcx> for T {
1045     default fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> bool {
1046         predicate.super_visit_with(self)
1047     }
1048 }
1049
1050 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
1051     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1052         fold_list(*self, folder, |tcx, v| tcx.intern_predicates(v))
1053     }
1054
1055     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1056         self.iter().any(|p| p.visit_with(visitor))
1057     }
1058 }
1059
1060 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
1061     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1062         self.iter().map(|x| x.fold_with(folder)).collect()
1063     }
1064
1065     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1066         self.iter().any(|t| t.visit_with(visitor))
1067     }
1068 }
1069
1070 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
1071     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1072         let ty = self.ty.fold_with(folder);
1073         let val = self.val.fold_with(folder);
1074         if ty != self.ty || val != self.val {
1075             folder.tcx().mk_const(ty::Const { ty, val })
1076         } else {
1077             *self
1078         }
1079     }
1080
1081     fn fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1082         folder.fold_const(*self)
1083     }
1084
1085     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1086         self.ty.visit_with(visitor) || self.val.visit_with(visitor)
1087     }
1088
1089     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1090         visitor.visit_const(self)
1091     }
1092 }
1093
1094 impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
1095     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1096         match *self {
1097             ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
1098             ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
1099             ty::ConstKind::Unevaluated(did, substs, promoted) => {
1100                 ty::ConstKind::Unevaluated(did, substs.fold_with(folder), promoted)
1101             }
1102             ty::ConstKind::Value(_)
1103             | ty::ConstKind::Bound(..)
1104             | ty::ConstKind::Placeholder(..)
1105             | ty::ConstKind::Error(_) => *self,
1106         }
1107     }
1108
1109     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1110         match *self {
1111             ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
1112             ty::ConstKind::Param(p) => p.visit_with(visitor),
1113             ty::ConstKind::Unevaluated(_, substs, _) => substs.visit_with(visitor),
1114             ty::ConstKind::Value(_)
1115             | ty::ConstKind::Bound(..)
1116             | ty::ConstKind::Placeholder(_)
1117             | ty::ConstKind::Error(_) => false,
1118         }
1119     }
1120 }
1121
1122 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
1123     fn super_fold_with<F: TypeFolder<'tcx>>(&self, _folder: &mut F) -> Self {
1124         *self
1125     }
1126
1127     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
1128         false
1129     }
1130 }
1131
1132 // Does the equivalent of
1133 // ```
1134 // let v = self.iter().map(|p| p.fold_with(folder)).collect::<SmallVec<[_; 8]>>();
1135 // folder.tcx().intern_*(&v)
1136 // ```
1137 fn fold_list<'tcx, F, T>(
1138     list: &'tcx ty::List<T>,
1139     folder: &mut F,
1140     intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>,
1141 ) -> &'tcx ty::List<T>
1142 where
1143     F: TypeFolder<'tcx>,
1144     T: TypeFoldable<'tcx> + PartialEq + Copy,
1145 {
1146     let mut iter = list.iter();
1147     // Look for the first element that changed
1148     if let Some((i, new_t)) = iter.by_ref().enumerate().find_map(|(i, t)| {
1149         let new_t = t.fold_with(folder);
1150         if new_t == t { None } else { Some((i, new_t)) }
1151     }) {
1152         // An element changed, prepare to intern the resulting list
1153         let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len());
1154         new_list.extend_from_slice(&list[..i]);
1155         new_list.push(new_t);
1156         new_list.extend(iter.map(|t| t.fold_with(folder)));
1157         intern(folder.tcx(), &new_list)
1158     } else {
1159         list
1160     }
1161 }