compiler/rustc_middle/src/ty/structural_impls.rs

   1 //! This module contains implements of the `Lift` and `TypeFoldable`
   2 //! traits for various types in the Rust compiler. Most are written by
   3 //! hand, though we've recently added some macros and proc-macros to help with the tedium.
   4
   5 use crate::mir::interpret;
   6 use crate::mir::{Field, ProjectionKind};
   7 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
   8 use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
   9 use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
  10 use crate::ty::{self, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
  11 use rustc_data_structures::functor::IdFunctor;
  12 use rustc_hir::def::Namespace;
  13 use rustc_index::vec::{Idx, IndexVec};
  14
  15 use std::fmt;
  16 use std::mem::ManuallyDrop;
  17 use std::ops::ControlFlow;
  18 use std::rc::Rc;
  19 use std::sync::Arc;
  20
  21 impl fmt::Debug for ty::TraitDef {
  22     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  23         ty::tls::with(|tcx| {
  24             with_no_trimmed_paths!({
  25                 f.write_str(
  26                     &FmtPrinter::new(tcx, Namespace::TypeNS)
  27                         .print_def_path(self.def_id, &[])?
  28                         .into_buffer(),
  29                 )
  30             })
  31         })
  32     }
  33 }
  34
  35 impl<'tcx> fmt::Debug for ty::AdtDef<'tcx> {
  36     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  37         ty::tls::with(|tcx| {
  38             with_no_trimmed_paths!({
  39                 f.write_str(
  40                     &FmtPrinter::new(tcx, Namespace::TypeNS)
  41                         .print_def_path(self.did(), &[])?
  42                         .into_buffer(),
  43                 )
  44             })
  45         })
  46     }
  47 }
  48
  49 impl fmt::Debug for ty::UpvarId {
  50     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  51         let name = ty::tls::with(|tcx| tcx.hir().name(self.var_path.hir_id));
  52         write!(f, "UpvarId({:?};`{}`;{:?})", self.var_path.hir_id, name, self.closure_expr_id)
  53     }
  54 }
  55
  56 impl<'tcx> fmt::Debug for ty::ExistentialTraitRef<'tcx> {
  57     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  58         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
  59     }
  60 }
  61
  62 impl<'tcx> fmt::Debug for ty::adjustment::Adjustment<'tcx> {
  63     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  64         write!(f, "{:?} -> {}", self.kind, self.target)
  65     }
  66 }
  67
  68 impl fmt::Debug for ty::BoundRegionKind {
  69     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  70         match *self {
  71             ty::BrAnon(n) => write!(f, "BrAnon({:?})", n),
  72             ty::BrNamed(did, name) => {
  73                 if did.is_crate_root() {
  74                     write!(f, "BrNamed({})", name)
  75                 } else {
  76                     write!(f, "BrNamed({:?}, {})", did, name)
  77                 }
  78             }
  79             ty::BrEnv => write!(f, "BrEnv"),
  80         }
  81     }
  82 }
  83
  84 impl fmt::Debug for ty::FreeRegion {
  85     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  86         write!(f, "ReFree({:?}, {:?})", self.scope, self.bound_region)
  87     }
  88 }
  89
  90 impl<'tcx> fmt::Debug for ty::FnSig<'tcx> {
  91     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  92         write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
  93     }
  94 }
  95
  96 impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
  97     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  98         write!(f, "_#{}c", self.index)
  99     }
 100 }
 101
 102 impl fmt::Debug for ty::RegionVid {
 103     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 104         write!(f, "'_#{}r", self.index())
 105     }
 106 }
 107
 108 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
 109     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 110         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
 111     }
 112 }
 113
 114 impl<'tcx> fmt::Debug for Ty<'tcx> {
 115     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 116         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
 117     }
 118 }
 119
 120 impl fmt::Debug for ty::ParamTy {
 121     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 122         write!(f, "{}/#{}", self.name, self.index)
 123     }
 124 }
 125
 126 impl fmt::Debug for ty::ParamConst {
 127     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 128         write!(f, "{}/#{}", self.name, self.index)
 129     }
 130 }
 131
 132 impl<'tcx> fmt::Debug for ty::TraitPredicate<'tcx> {
 133     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 134         if let ty::BoundConstness::ConstIfConst = self.constness {
 135             write!(f, "~const ")?;
 136         }
 137         write!(f, "TraitPredicate({:?}, polarity:{:?})", self.trait_ref, self.polarity)
 138     }
 139 }
 140
 141 impl<'tcx> fmt::Debug for ty::ProjectionPredicate<'tcx> {
 142     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 143         write!(f, "ProjectionPredicate({:?}, {:?})", self.projection_ty, self.term)
 144     }
 145 }
 146
 147 impl<'tcx> fmt::Debug for ty::Predicate<'tcx> {
 148     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 149         write!(f, "{:?}", self.kind())
 150     }
 151 }
 152
 153 impl<'tcx> fmt::Debug for ty::PredicateKind<'tcx> {
 154     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 155         match *self {
 156             ty::PredicateKind::Trait(ref a) => a.fmt(f),
 157             ty::PredicateKind::Subtype(ref pair) => pair.fmt(f),
 158             ty::PredicateKind::Coerce(ref pair) => pair.fmt(f),
 159             ty::PredicateKind::RegionOutlives(ref pair) => pair.fmt(f),
 160             ty::PredicateKind::TypeOutlives(ref pair) => pair.fmt(f),
 161             ty::PredicateKind::Projection(ref pair) => pair.fmt(f),
 162             ty::PredicateKind::WellFormed(data) => write!(f, "WellFormed({:?})", data),
 163             ty::PredicateKind::ObjectSafe(trait_def_id) => {
 164                 write!(f, "ObjectSafe({:?})", trait_def_id)
 165             }
 166             ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
 167                 write!(f, "ClosureKind({:?}, {:?}, {:?})", closure_def_id, closure_substs, kind)
 168             }
 169             ty::PredicateKind::ConstEvaluatable(uv) => {
 170                 write!(f, "ConstEvaluatable({:?}, {:?})", uv.def, uv.substs)
 171             }
 172             ty::PredicateKind::ConstEquate(c1, c2) => write!(f, "ConstEquate({:?}, {:?})", c1, c2),
 173             ty::PredicateKind::TypeWellFormedFromEnv(ty) => {
 174                 write!(f, "TypeWellFormedFromEnv({:?})", ty)
 175             }
 176         }
 177     }
 178 }
 179
 180 ///////////////////////////////////////////////////////////////////////////
 181 // Atomic structs
 182 //
 183 // For things that don't carry any arena-allocated data (and are
 184 // copy...), just add them to this list.
 185
 186 TrivialTypeTraversalAndLiftImpls! {
 187     (),
 188     bool,
 189     usize,
 190     ::rustc_target::abi::VariantIdx,
 191     u32,
 192     u64,
 193     String,
 194     crate::middle::region::Scope,
 195     crate::ty::FloatTy,
 196     ::rustc_ast::InlineAsmOptions,
 197     ::rustc_ast::InlineAsmTemplatePiece,
 198     ::rustc_ast::NodeId,
 199     ::rustc_span::symbol::Symbol,
 200     ::rustc_hir::def::Res,
 201     ::rustc_hir::def_id::DefId,
 202     ::rustc_hir::def_id::LocalDefId,
 203     ::rustc_hir::HirId,
 204     ::rustc_hir::MatchSource,
 205     ::rustc_hir::Mutability,
 206     ::rustc_hir::Unsafety,
 207     ::rustc_target::asm::InlineAsmRegOrRegClass,
 208     ::rustc_target::spec::abi::Abi,
 209     crate::mir::coverage::ExpressionOperandId,
 210     crate::mir::coverage::CounterValueReference,
 211     crate::mir::coverage::InjectedExpressionId,
 212     crate::mir::coverage::InjectedExpressionIndex,
 213     crate::mir::coverage::MappedExpressionIndex,
 214     crate::mir::Local,
 215     crate::mir::Promoted,
 216     crate::traits::Reveal,
 217     crate::ty::adjustment::AutoBorrowMutability,
 218     crate::ty::AdtKind,
 219     crate::ty::BoundConstness,
 220     // Including `BoundRegionKind` is a *bit* dubious, but direct
 221     // references to bound region appear in `ty::Error`, and aren't
 222     // really meant to be folded. In general, we can only fold a fully
 223     // general `Region`.
 224     crate::ty::BoundRegionKind,
 225     crate::ty::AssocItem,
 226     crate::ty::AssocKind,
 227     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
 228     crate::ty::ClosureKind,
 229     crate::ty::FreeRegion,
 230     crate::ty::InferTy,
 231     crate::ty::IntVarValue,
 232     crate::ty::ParamConst,
 233     crate::ty::ParamTy,
 234     crate::ty::adjustment::PointerCast,
 235     crate::ty::RegionVid,
 236     crate::ty::UniverseIndex,
 237     crate::ty::Variance,
 238     ::rustc_span::Span,
 239     ::rustc_errors::ErrorGuaranteed,
 240     Field,
 241     interpret::Scalar,
 242     rustc_target::abi::Size,
 243     ty::DelaySpanBugEmitted,
 244     rustc_type_ir::DebruijnIndex,
 245     ty::BoundVar,
 246     ty::Placeholder<ty::BoundVar>,
 247 }
 248
 249 TrivialTypeTraversalAndLiftImpls! {
 250     for<'tcx> {
 251         ty::ValTree<'tcx>,
 252     }
 253 }
 254
 255 ///////////////////////////////////////////////////////////////////////////
 256 // Lift implementations
 257
 258 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
 259     type Lifted = (A::Lifted, B::Lifted);
 260     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 261         Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
 262     }
 263 }
 264
 265 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
 266     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
 267     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 268         Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
 269     }
 270 }
 271
 272 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 273     type Lifted = Option<T::Lifted>;
 274     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 275         Some(match self {
 276             Some(x) => Some(tcx.lift(x)?),
 277             None => None,
 278         })
 279     }
 280 }
 281
 282 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
 283     type Lifted = Result<T::Lifted, E::Lifted>;
 284     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 285         match self {
 286             Ok(x) => tcx.lift(x).map(Ok),
 287             Err(e) => tcx.lift(e).map(Err),
 288         }
 289     }
 290 }
 291
 292 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
 293     type Lifted = Box<T::Lifted>;
 294     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 295         Some(Box::new(tcx.lift(*self)?))
 296     }
 297 }
 298
 299 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
 300     type Lifted = Rc<T::Lifted>;
 301     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 302         Some(Rc::new(tcx.lift(self.as_ref().clone())?))
 303     }
 304 }
 305
 306 impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
 307     type Lifted = Arc<T::Lifted>;
 308     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 309         Some(Arc::new(tcx.lift(self.as_ref().clone())?))
 310     }
 311 }
 312 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
 313     type Lifted = Vec<T::Lifted>;
 314     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 315         self.into_iter().map(|v| tcx.lift(v)).collect()
 316     }
 317 }
 318
 319 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
 320     type Lifted = IndexVec<I, T::Lifted>;
 321     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 322         self.into_iter().map(|e| tcx.lift(e)).collect()
 323     }
 324 }
 325
 326 impl<'a, 'tcx> Lift<'tcx> for Term<'a> {
 327     type Lifted = ty::Term<'tcx>;
 328     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 329         Some(
 330             match self.unpack() {
 331                 TermKind::Ty(ty) => TermKind::Ty(tcx.lift(ty)?),
 332                 TermKind::Const(c) => TermKind::Const(tcx.lift(c)?),
 333             }
 334             .pack(),
 335         )
 336     }
 337 }
 338 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
 339     type Lifted = ty::ParamEnv<'tcx>;
 340     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
 341         tcx.lift(self.caller_bounds())
 342             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal(), self.constness()))
 343     }
 344 }
 345
 346 ///////////////////////////////////////////////////////////////////////////
 347 // TypeFoldable implementations.
 348
 349 /// AdtDefs are basically the same as a DefId.
 350 impl<'tcx> TypeFoldable<'tcx> for ty::AdtDef<'tcx> {
 351     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
 352         Ok(self)
 353     }
 354 }
 355
 356 impl<'tcx> TypeVisitable<'tcx> for ty::AdtDef<'tcx> {
 357     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 358         ControlFlow::CONTINUE
 359     }
 360 }
 361
 362 impl<'tcx, T: TypeFoldable<'tcx>, U: TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 363     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 364         self,
 365         folder: &mut F,
 366     ) -> Result<(T, U), F::Error> {
 367         Ok((self.0.try_fold_with(folder)?, self.1.try_fold_with(folder)?))
 368     }
 369 }
 370
 371 impl<'tcx, T: TypeVisitable<'tcx>, U: TypeVisitable<'tcx>> TypeVisitable<'tcx> for (T, U) {
 372     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 373         self.0.visit_with(visitor)?;
 374         self.1.visit_with(visitor)
 375     }
 376 }
 377
 378 impl<'tcx, A: TypeFoldable<'tcx>, B: TypeFoldable<'tcx>, C: TypeFoldable<'tcx>> TypeFoldable<'tcx>
 379     for (A, B, C)
 380 {
 381     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 382         self,
 383         folder: &mut F,
 384     ) -> Result<(A, B, C), F::Error> {
 385         Ok((
 386             self.0.try_fold_with(folder)?,
 387             self.1.try_fold_with(folder)?,
 388             self.2.try_fold_with(folder)?,
 389         ))
 390     }
 391 }
 392
 393 impl<'tcx, A: TypeVisitable<'tcx>, B: TypeVisitable<'tcx>, C: TypeVisitable<'tcx>>
 394     TypeVisitable<'tcx> for (A, B, C)
 395 {
 396     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 397         self.0.visit_with(visitor)?;
 398         self.1.visit_with(visitor)?;
 399         self.2.visit_with(visitor)
 400     }
 401 }
 402
 403 EnumTypeTraversalImpl! {
 404     impl<'tcx, T> TypeFoldable<'tcx> for Option<T> {
 405         (Some)(a),
 406         (None),
 407     } where T: TypeFoldable<'tcx>
 408 }
 409 EnumTypeTraversalImpl! {
 410     impl<'tcx, T> TypeVisitable<'tcx> for Option<T> {
 411         (Some)(a),
 412         (None),
 413     } where T: TypeVisitable<'tcx>
 414 }
 415
 416 EnumTypeTraversalImpl! {
 417     impl<'tcx, T, E> TypeFoldable<'tcx> for Result<T, E> {
 418         (Ok)(a),
 419         (Err)(a),
 420     } where T: TypeFoldable<'tcx>, E: TypeFoldable<'tcx>,
 421 }
 422 EnumTypeTraversalImpl! {
 423     impl<'tcx, T, E> TypeVisitable<'tcx> for Result<T, E> {
 424         (Ok)(a),
 425         (Err)(a),
 426     } where T: TypeVisitable<'tcx>, E: TypeVisitable<'tcx>,
 427 }
 428
 429 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 430     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 431         mut self,
 432         folder: &mut F,
 433     ) -> Result<Self, F::Error> {
 434         // We merely want to replace the contained `T`, if at all possible,
 435         // so that we don't needlessly allocate a new `Rc` or indeed clone
 436         // the contained type.
 437         unsafe {
 438             // First step is to ensure that we have a unique reference to
 439             // the contained type, which `Rc::make_mut` will accomplish (by
 440             // allocating a new `Rc` and cloning the `T` only if required).
 441             // This is done *before* casting to `Rc<ManuallyDrop<T>>` so that
 442             // panicking during `make_mut` does not leak the `T`.
 443             Rc::make_mut(&mut self);
 444
 445             // Casting to `Rc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 446             // is `repr(transparent)`.
 447             let ptr = Rc::into_raw(self).cast::<ManuallyDrop<T>>();
 448             let mut unique = Rc::from_raw(ptr);
 449
 450             // Call to `Rc::make_mut` above guarantees that `unique` is the
 451             // sole reference to the contained value, so we can avoid doing
 452             // a checked `get_mut` here.
 453             let slot = Rc::get_mut_unchecked(&mut unique);
 454
 455             // Semantically move the contained type out from `unique`, fold
 456             // it, then move the folded value back into `unique`.  Should
 457             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 458             // value is not re-dropped.
 459             let owned = ManuallyDrop::take(slot);
 460             let folded = owned.try_fold_with(folder)?;
 461             *slot = ManuallyDrop::new(folded);
 462
 463             // Cast back to `Rc<T>`.
 464             Ok(Rc::from_raw(Rc::into_raw(unique).cast()))
 465         }
 466     }
 467 }
 468
 469 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Rc<T> {
 470     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 471         (**self).visit_with(visitor)
 472     }
 473 }
 474
 475 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Arc<T> {
 476     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(
 477         mut self,
 478         folder: &mut F,
 479     ) -> Result<Self, F::Error> {
 480         // We merely want to replace the contained `T`, if at all possible,
 481         // so that we don't needlessly allocate a new `Arc` or indeed clone
 482         // the contained type.
 483         unsafe {
 484             // First step is to ensure that we have a unique reference to
 485             // the contained type, which `Arc::make_mut` will accomplish (by
 486             // allocating a new `Arc` and cloning the `T` only if required).
 487             // This is done *before* casting to `Arc<ManuallyDrop<T>>` so that
 488             // panicking during `make_mut` does not leak the `T`.
 489             Arc::make_mut(&mut self);
 490
 491             // Casting to `Arc<ManuallyDrop<T>>` is safe because `ManuallyDrop`
 492             // is `repr(transparent)`.
 493             let ptr = Arc::into_raw(self).cast::<ManuallyDrop<T>>();
 494             let mut unique = Arc::from_raw(ptr);
 495
 496             // Call to `Arc::make_mut` above guarantees that `unique` is the
 497             // sole reference to the contained value, so we can avoid doing
 498             // a checked `get_mut` here.
 499             let slot = Arc::get_mut_unchecked(&mut unique);
 500
 501             // Semantically move the contained type out from `unique`, fold
 502             // it, then move the folded value back into `unique`.  Should
 503             // folding fail, `ManuallyDrop` ensures that the "moved-out"
 504             // value is not re-dropped.
 505             let owned = ManuallyDrop::take(slot);
 506             let folded = owned.try_fold_with(folder)?;
 507             *slot = ManuallyDrop::new(folded);
 508
 509             // Cast back to `Arc<T>`.
 510             Ok(Arc::from_raw(Arc::into_raw(unique).cast()))
 511         }
 512     }
 513 }
 514
 515 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Arc<T> {
 516     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 517         (**self).visit_with(visitor)
 518     }
 519 }
 520
 521 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 522     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 523         self.try_map_id(|value| value.try_fold_with(folder))
 524     }
 525 }
 526
 527 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<T> {
 528     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 529         (**self).visit_with(visitor)
 530     }
 531 }
 532
 533 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 534     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 535         self.try_map_id(|t| t.try_fold_with(folder))
 536     }
 537 }
 538
 539 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Vec<T> {
 540     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 541         self.iter().try_for_each(|t| t.visit_with(visitor))
 542     }
 543 }
 544
 545 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for &[T] {
 546     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 547         self.iter().try_for_each(|t| t.visit_with(visitor))
 548     }
 549 }
 550
 551 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<[T]> {
 552     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 553         self.try_map_id(|t| t.try_fold_with(folder))
 554     }
 555 }
 556
 557 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for Box<[T]> {
 558     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 559         self.iter().try_for_each(|t| t.visit_with(visitor))
 560     }
 561 }
 562
 563 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<'tcx, T> {
 564     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 565         folder.try_fold_binder(self)
 566     }
 567 }
 568
 569 impl<'tcx, T: TypeVisitable<'tcx>> TypeVisitable<'tcx> for ty::Binder<'tcx, T> {
 570     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 571         visitor.visit_binder(self)
 572     }
 573 }
 574
 575 impl<'tcx, T: TypeFoldable<'tcx>> TypeSuperFoldable<'tcx> for ty::Binder<'tcx, T> {
 576     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 577         self,
 578         folder: &mut F,
 579     ) -> Result<Self, F::Error> {
 580         self.try_map_bound(|ty| ty.try_fold_with(folder))
 581     }
 582 }
 583
 584 impl<'tcx, T: TypeVisitable<'tcx>> TypeSuperVisitable<'tcx> for ty::Binder<'tcx, T> {
 585     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 586         self.as_ref().skip_binder().visit_with(visitor)
 587     }
 588 }
 589
 590 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> {
 591     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 592         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_poly_existential_predicates(v))
 593     }
 594 }
 595
 596 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ProjectionKind> {
 597     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 598         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_projs(v))
 599     }
 600 }
 601
 602 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 603     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 604         folder.try_fold_ty(self)
 605     }
 606 }
 607
 608 impl<'tcx> TypeVisitable<'tcx> for Ty<'tcx> {
 609     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 610         visitor.visit_ty(*self)
 611     }
 612 }
 613
 614 impl<'tcx> TypeSuperFoldable<'tcx> for Ty<'tcx> {
 615     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 616         self,
 617         folder: &mut F,
 618     ) -> Result<Self, F::Error> {
 619         let kind = match *self.kind() {
 620             ty::RawPtr(tm) => ty::RawPtr(tm.try_fold_with(folder)?),
 621             ty::Array(typ, sz) => ty::Array(typ.try_fold_with(folder)?, sz.try_fold_with(folder)?),
 622             ty::Slice(typ) => ty::Slice(typ.try_fold_with(folder)?),
 623             ty::Adt(tid, substs) => ty::Adt(tid, substs.try_fold_with(folder)?),
 624             ty::Dynamic(trait_ty, region, representation) => ty::Dynamic(
 625                 trait_ty.try_fold_with(folder)?,
 626                 region.try_fold_with(folder)?,
 627                 representation,
 628             ),
 629             ty::Tuple(ts) => ty::Tuple(ts.try_fold_with(folder)?),
 630             ty::FnDef(def_id, substs) => ty::FnDef(def_id, substs.try_fold_with(folder)?),
 631             ty::FnPtr(f) => ty::FnPtr(f.try_fold_with(folder)?),
 632             ty::Ref(r, ty, mutbl) => {
 633                 ty::Ref(r.try_fold_with(folder)?, ty.try_fold_with(folder)?, mutbl)
 634             }
 635             ty::Generator(did, substs, movability) => {
 636                 ty::Generator(did, substs.try_fold_with(folder)?, movability)
 637             }
 638             ty::GeneratorWitness(types) => ty::GeneratorWitness(types.try_fold_with(folder)?),
 639             ty::Closure(did, substs) => ty::Closure(did, substs.try_fold_with(folder)?),
 640             ty::Projection(data) => ty::Projection(data.try_fold_with(folder)?),
 641             ty::Opaque(did, substs) => ty::Opaque(did, substs.try_fold_with(folder)?),
 642
 643             ty::Bool
 644             | ty::Char
 645             | ty::Str
 646             | ty::Int(_)
 647             | ty::Uint(_)
 648             | ty::Float(_)
 649             | ty::Error(_)
 650             | ty::Infer(_)
 651             | ty::Param(..)
 652             | ty::Bound(..)
 653             | ty::Placeholder(..)
 654             | ty::Never
 655             | ty::Foreign(..) => return Ok(self),
 656         };
 657
 658         Ok(if *self.kind() == kind { self } else { folder.tcx().mk_ty(kind) })
 659     }
 660 }
 661
 662 impl<'tcx> TypeSuperVisitable<'tcx> for Ty<'tcx> {
 663     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 664         match self.kind() {
 665             ty::RawPtr(ref tm) => tm.visit_with(visitor),
 666             ty::Array(typ, sz) => {
 667                 typ.visit_with(visitor)?;
 668                 sz.visit_with(visitor)
 669             }
 670             ty::Slice(typ) => typ.visit_with(visitor),
 671             ty::Adt(_, substs) => substs.visit_with(visitor),
 672             ty::Dynamic(ref trait_ty, ref reg, _) => {
 673                 trait_ty.visit_with(visitor)?;
 674                 reg.visit_with(visitor)
 675             }
 676             ty::Tuple(ts) => ts.visit_with(visitor),
 677             ty::FnDef(_, substs) => substs.visit_with(visitor),
 678             ty::FnPtr(ref f) => f.visit_with(visitor),
 679             ty::Ref(r, ty, _) => {
 680                 r.visit_with(visitor)?;
 681                 ty.visit_with(visitor)
 682             }
 683             ty::Generator(_did, ref substs, _) => substs.visit_with(visitor),
 684             ty::GeneratorWitness(ref types) => types.visit_with(visitor),
 685             ty::Closure(_did, ref substs) => substs.visit_with(visitor),
 686             ty::Projection(ref data) => data.visit_with(visitor),
 687             ty::Opaque(_, ref substs) => substs.visit_with(visitor),
 688
 689             ty::Bool
 690             | ty::Char
 691             | ty::Str
 692             | ty::Int(_)
 693             | ty::Uint(_)
 694             | ty::Float(_)
 695             | ty::Error(_)
 696             | ty::Infer(_)
 697             | ty::Bound(..)
 698             | ty::Placeholder(..)
 699             | ty::Param(..)
 700             | ty::Never
 701             | ty::Foreign(..) => ControlFlow::CONTINUE,
 702         }
 703     }
 704 }
 705
 706 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
 707     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 708         folder.try_fold_region(self)
 709     }
 710 }
 711
 712 impl<'tcx> TypeVisitable<'tcx> for ty::Region<'tcx> {
 713     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 714         visitor.visit_region(*self)
 715     }
 716 }
 717
 718 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Region<'tcx> {
 719     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 720         self,
 721         _folder: &mut F,
 722     ) -> Result<Self, F::Error> {
 723         Ok(self)
 724     }
 725 }
 726
 727 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Region<'tcx> {
 728     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 729         ControlFlow::CONTINUE
 730     }
 731 }
 732
 733 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
 734     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 735         folder.try_fold_predicate(self)
 736     }
 737 }
 738
 739 impl<'tcx> TypeVisitable<'tcx> for ty::Predicate<'tcx> {
 740     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 741         visitor.visit_predicate(*self)
 742     }
 743
 744     #[inline]
 745     fn has_vars_bound_at_or_above(&self, binder: ty::DebruijnIndex) -> bool {
 746         self.outer_exclusive_binder() > binder
 747     }
 748
 749     #[inline]
 750     fn has_type_flags(&self, flags: ty::TypeFlags) -> bool {
 751         self.flags().intersects(flags)
 752     }
 753 }
 754
 755 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Predicate<'tcx> {
 756     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 757         self,
 758         folder: &mut F,
 759     ) -> Result<Self, F::Error> {
 760         let new = self.kind().try_fold_with(folder)?;
 761         Ok(folder.tcx().reuse_or_mk_predicate(self, new))
 762     }
 763 }
 764
 765 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Predicate<'tcx> {
 766     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 767         self.kind().visit_with(visitor)
 768     }
 769 }
 770
 771 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<ty::Predicate<'tcx>> {
 772     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 773         ty::util::fold_list(self, folder, |tcx, v| tcx.intern_predicates(v))
 774     }
 775 }
 776
 777 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
 778     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 779         self.try_map_id(|x| x.try_fold_with(folder))
 780     }
 781 }
 782
 783 impl<'tcx, T: TypeVisitable<'tcx>, I: Idx> TypeVisitable<'tcx> for IndexVec<I, T> {
 784     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 785         self.iter().try_for_each(|t| t.visit_with(visitor))
 786     }
 787 }
 788
 789 impl<'tcx> TypeFoldable<'tcx> for ty::Const<'tcx> {
 790     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 791         folder.try_fold_const(self)
 792     }
 793 }
 794
 795 impl<'tcx> TypeVisitable<'tcx> for ty::Const<'tcx> {
 796     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 797         visitor.visit_const(*self)
 798     }
 799 }
 800
 801 impl<'tcx> TypeSuperFoldable<'tcx> for ty::Const<'tcx> {
 802     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 803         self,
 804         folder: &mut F,
 805     ) -> Result<Self, F::Error> {
 806         let ty = self.ty().try_fold_with(folder)?;
 807         let kind = self.kind().try_fold_with(folder)?;
 808         if ty != self.ty() || kind != self.kind() {
 809             Ok(folder.tcx().mk_const(ty::ConstS { ty, kind }))
 810         } else {
 811             Ok(self)
 812         }
 813     }
 814 }
 815
 816 impl<'tcx> TypeSuperVisitable<'tcx> for ty::Const<'tcx> {
 817     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 818         self.ty().visit_with(visitor)?;
 819         self.kind().visit_with(visitor)
 820     }
 821 }
 822
 823 impl<'tcx> TypeFoldable<'tcx> for InferConst<'tcx> {
 824     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, _folder: &mut F) -> Result<Self, F::Error> {
 825         Ok(self)
 826     }
 827 }
 828
 829 impl<'tcx> TypeVisitable<'tcx> for InferConst<'tcx> {
 830     fn visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> ControlFlow<V::BreakTy> {
 831         ControlFlow::CONTINUE
 832     }
 833 }
 834
 835 impl<'tcx> TypeFoldable<'tcx> for ty::UnevaluatedConst<'tcx> {
 836     fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
 837         folder.try_fold_ty_unevaluated(self)
 838     }
 839 }
 840
 841 impl<'tcx> TypeVisitable<'tcx> for ty::UnevaluatedConst<'tcx> {
 842     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 843         visitor.visit_ty_unevaluated(*self)
 844     }
 845 }
 846
 847 impl<'tcx> TypeSuperFoldable<'tcx> for ty::UnevaluatedConst<'tcx> {
 848     fn try_super_fold_with<F: FallibleTypeFolder<'tcx>>(
 849         self,
 850         folder: &mut F,
 851     ) -> Result<Self, F::Error> {
 852         Ok(ty::UnevaluatedConst { def: self.def, substs: self.substs.try_fold_with(folder)? })
 853     }
 854 }
 855
 856 impl<'tcx> TypeSuperVisitable<'tcx> for ty::UnevaluatedConst<'tcx> {
 857     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
 858         self.substs.visit_with(visitor)
 859     }
 860 }