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