src/librustc/ty/structural_impls.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use infer::type_variable;
  12 use ty::{self, Lift, Ty, TyCtxt};
  13 use ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
  14 use rustc_data_structures::accumulate_vec::AccumulateVec;
  15 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
  16
  17 use std::rc::Rc;
  18 use syntax::abi;
  19
  20 use hir;
  21
  22 ///////////////////////////////////////////////////////////////////////////
  23 // Lift implementations
  24
  25 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
  26     type Lifted = (A::Lifted, B::Lifted);
  27     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  28         tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b)))
  29     }
  30 }
  31
  32 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
  33     type Lifted = Option<T::Lifted>;
  34     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  35         match *self {
  36             Some(ref x) => tcx.lift(x).map(Some),
  37             None => Some(None)
  38         }
  39     }
  40 }
  41
  42 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
  43     type Lifted = Result<T::Lifted, E::Lifted>;
  44     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  45         match *self {
  46             Ok(ref x) => tcx.lift(x).map(Ok),
  47             Err(ref e) => tcx.lift(e).map(Err)
  48         }
  49     }
  50 }
  51
  52 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] {
  53     type Lifted = Vec<T::Lifted>;
  54     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  55         // type annotation needed to inform `projection_must_outlive`
  56         let mut result : Vec<<T as Lift<'tcx>>::Lifted>
  57             = Vec::with_capacity(self.len());
  58         for x in self {
  59             if let Some(value) = tcx.lift(x) {
  60                 result.push(value);
  61             } else {
  62                 return None;
  63             }
  64         }
  65         Some(result)
  66     }
  67 }
  68
  69 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
  70     type Lifted = Vec<T::Lifted>;
  71     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  72         tcx.lift(&self[..])
  73     }
  74 }
  75
  76 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
  77     type Lifted = ty::TraitRef<'tcx>;
  78     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  79         tcx.lift(&self.substs).map(|substs| ty::TraitRef {
  80             def_id: self.def_id,
  81             substs: substs
  82         })
  83     }
  84 }
  85
  86 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
  87     type Lifted = ty::ExistentialTraitRef<'tcx>;
  88     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
  89         tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef {
  90             def_id: self.def_id,
  91             substs: substs
  92         })
  93     }
  94 }
  95
  96 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
  97     type Lifted = ty::TraitPredicate<'tcx>;
  98     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
  99                              -> Option<ty::TraitPredicate<'tcx>> {
 100         tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate {
 101             trait_ref: trait_ref
 102         })
 103     }
 104 }
 105
 106 impl<'a, 'tcx> Lift<'tcx> for ty::EquatePredicate<'a> {
 107     type Lifted = ty::EquatePredicate<'tcx>;
 108     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 109                              -> Option<ty::EquatePredicate<'tcx>> {
 110         tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::EquatePredicate(a, b))
 111     }
 112 }
 113
 114 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 115     type Lifted = ty::SubtypePredicate<'tcx>;
 116     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 117                              -> Option<ty::SubtypePredicate<'tcx>> {
 118         tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
 119             a_is_expected: self.a_is_expected,
 120             a: a,
 121             b: b,
 122         })
 123     }
 124 }
 125
 126 impl<'tcx, A: Copy+Lift<'tcx>, B: Copy+Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
 127     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
 128     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 129         tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
 130     }
 131 }
 132
 133 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
 134     type Lifted = ty::ProjectionTy<'tcx>;
 135     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 136                              -> Option<ty::ProjectionTy<'tcx>> {
 137         tcx.lift(&self.trait_ref).map(|trait_ref| {
 138             ty::ProjectionTy {
 139                 trait_ref: trait_ref,
 140                 item_name: self.item_name
 141             }
 142         })
 143     }
 144 }
 145
 146 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
 147     type Lifted = ty::ProjectionPredicate<'tcx>;
 148     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>)
 149                              -> Option<ty::ProjectionPredicate<'tcx>> {
 150         tcx.lift(&(self.projection_ty, self.ty)).map(|(projection_ty, ty)| {
 151             ty::ProjectionPredicate {
 152                 projection_ty: projection_ty,
 153                 ty: ty
 154             }
 155         })
 156     }
 157 }
 158
 159 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 160     type Lifted = ty::ExistentialProjection<'tcx>;
 161     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 162         tcx.lift(&(self.trait_ref, self.ty)).map(|(trait_ref, ty)| {
 163             ty::ExistentialProjection {
 164                 trait_ref: trait_ref,
 165                 item_name: self.item_name,
 166                 ty: ty
 167             }
 168         })
 169     }
 170 }
 171
 172 impl<'a, 'tcx> Lift<'tcx> for ty::Predicate<'a> {
 173     type Lifted = ty::Predicate<'tcx>;
 174     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 175         match *self {
 176             ty::Predicate::Trait(ref binder) => {
 177                 tcx.lift(binder).map(ty::Predicate::Trait)
 178             }
 179             ty::Predicate::Equate(ref binder) => {
 180                 tcx.lift(binder).map(ty::Predicate::Equate)
 181             }
 182             ty::Predicate::Subtype(ref binder) => {
 183                 tcx.lift(binder).map(ty::Predicate::Subtype)
 184             }
 185             ty::Predicate::RegionOutlives(ref binder) => {
 186                 tcx.lift(binder).map(ty::Predicate::RegionOutlives)
 187             }
 188             ty::Predicate::TypeOutlives(ref binder) => {
 189                 tcx.lift(binder).map(ty::Predicate::TypeOutlives)
 190             }
 191             ty::Predicate::Projection(ref binder) => {
 192                 tcx.lift(binder).map(ty::Predicate::Projection)
 193             }
 194             ty::Predicate::WellFormed(ty) => {
 195                 tcx.lift(&ty).map(ty::Predicate::WellFormed)
 196             }
 197             ty::Predicate::ClosureKind(closure_def_id, kind) => {
 198                 Some(ty::Predicate::ClosureKind(closure_def_id, kind))
 199             }
 200             ty::Predicate::ObjectSafe(trait_def_id) => {
 201                 Some(ty::Predicate::ObjectSafe(trait_def_id))
 202             }
 203         }
 204     }
 205 }
 206
 207 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> {
 208     type Lifted = ty::Binder<T::Lifted>;
 209     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 210         tcx.lift(&self.0).map(|x| ty::Binder(x))
 211     }
 212 }
 213
 214 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
 215     type Lifted = ty::ClosureSubsts<'tcx>;
 216     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 217         tcx.lift(&self.substs).map(|substs| {
 218             ty::ClosureSubsts { substs: substs }
 219         })
 220     }
 221 }
 222
 223 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 224     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
 225     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 226         match *self {
 227             ty::adjustment::AutoBorrow::Ref(r, m) => {
 228                 tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
 229             }
 230             ty::adjustment::AutoBorrow::RawPtr(m) => {
 231                 Some(ty::adjustment::AutoBorrow::RawPtr(m))
 232             }
 233         }
 234     }
 235 }
 236
 237 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 238     type Lifted = ty::FnSig<'tcx>;
 239     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 240         tcx.lift(&self.inputs_and_output).map(|x| {
 241             ty::FnSig {
 242                 inputs_and_output: x,
 243                 variadic: self.variadic,
 244                 unsafety: self.unsafety,
 245                 abi: self.abi,
 246             }
 247         })
 248     }
 249 }
 250
 251 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
 252     type Lifted = ty::error::ExpectedFound<T::Lifted>;
 253     fn lift_to_tcx<'a, 'gcx>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 254         tcx.lift(&self.expected).and_then(|expected| {
 255             tcx.lift(&self.found).map(|found| {
 256                 ty::error::ExpectedFound {
 257                     expected: expected,
 258                     found: found
 259                 }
 260             })
 261         })
 262     }
 263 }
 264
 265 impl<'a, 'tcx> Lift<'tcx> for type_variable::Default<'a> {
 266     type Lifted = type_variable::Default<'tcx>;
 267     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 268         tcx.lift(&self.ty).map(|ty| {
 269             type_variable::Default {
 270                 ty: ty,
 271                 origin_span: self.origin_span,
 272                 def_id: self.def_id
 273             }
 274         })
 275     }
 276 }
 277
 278 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
 279     type Lifted = ty::error::TypeError<'tcx>;
 280     fn lift_to_tcx<'b, 'gcx>(&self, tcx: TyCtxt<'b, 'gcx, 'tcx>) -> Option<Self::Lifted> {
 281         use ty::error::TypeError::*;
 282
 283         Some(match *self {
 284             Mismatch => Mismatch,
 285             UnsafetyMismatch(x) => UnsafetyMismatch(x),
 286             AbiMismatch(x) => AbiMismatch(x),
 287             Mutability => Mutability,
 288             TupleSize(x) => TupleSize(x),
 289             FixedArraySize(x) => FixedArraySize(x),
 290             ArgCount => ArgCount,
 291             RegionsDoesNotOutlive(a, b) => {
 292                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b))
 293             }
 294             RegionsNotSame(a, b) => {
 295                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsNotSame(a, b))
 296             }
 297             RegionsNoOverlap(a, b) => {
 298                 return tcx.lift(&(a, b)).map(|(a, b)| RegionsNoOverlap(a, b))
 299             }
 300             RegionsInsufficientlyPolymorphic(a, b, ref c) => {
 301                 let c = c.clone();
 302                 return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b, c))
 303             }
 304             RegionsOverlyPolymorphic(a, b, ref c) => {
 305                 let c = c.clone();
 306                 return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b, c))
 307             }
 308             IntMismatch(x) => IntMismatch(x),
 309             FloatMismatch(x) => FloatMismatch(x),
 310             Traits(x) => Traits(x),
 311             VariadicMismatch(x) => VariadicMismatch(x),
 312             CyclicTy => CyclicTy,
 313             ProjectionNameMismatched(x) => ProjectionNameMismatched(x),
 314             ProjectionBoundsLength(x) => ProjectionBoundsLength(x),
 315
 316             Sorts(ref x) => return tcx.lift(x).map(Sorts),
 317             TyParamDefaultMismatch(ref x) => {
 318                 return tcx.lift(x).map(TyParamDefaultMismatch)
 319             }
 320             ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch)
 321         })
 322     }
 323 }
 324
 325 ///////////////////////////////////////////////////////////////////////////
 326 // TypeFoldable implementations.
 327 //
 328 // Ideally, each type should invoke `folder.fold_foo(self)` and
 329 // nothing else. In some cases, though, we haven't gotten around to
 330 // adding methods on the `folder` yet, and thus the folding is
 331 // hard-coded here. This is less-flexible, because folders cannot
 332 // override the behavior, but there are a lot of random types and one
 333 // can easily refactor the folding into the TypeFolder trait as
 334 // needed.
 335
 336 macro_rules! CopyImpls {
 337     ($($ty:ty),+) => {
 338         $(
 339             impl<'tcx> TypeFoldable<'tcx> for $ty {
 340                 fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _: &mut F) -> $ty {
 341                     *self
 342                 }
 343
 344                 fn super_visit_with<F: TypeVisitor<'tcx>>(&self, _: &mut F) -> bool {
 345                     false
 346                 }
 347             }
 348         )+
 349     }
 350 }
 351
 352 CopyImpls! { (), hir::Unsafety, abi::Abi }
 353
 354 impl<'tcx, T:TypeFoldable<'tcx>, U:TypeFoldable<'tcx>> TypeFoldable<'tcx> for (T, U) {
 355     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> (T, U) {
 356         (self.0.fold_with(folder), self.1.fold_with(folder))
 357     }
 358
 359     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 360         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 361     }
 362 }
 363
 364 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Option<T> {
 365     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 366         self.as_ref().map(|t| t.fold_with(folder))
 367     }
 368
 369     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 370         self.iter().any(|t| t.visit_with(visitor))
 371     }
 372 }
 373
 374 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Rc<T> {
 375     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 376         Rc::new((**self).fold_with(folder))
 377     }
 378
 379     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 380         (**self).visit_with(visitor)
 381     }
 382 }
 383
 384 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Box<T> {
 385     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 386         let content: T = (**self).fold_with(folder);
 387         box content
 388     }
 389
 390     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 391         (**self).visit_with(visitor)
 392     }
 393 }
 394
 395 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for Vec<T> {
 396     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 397         self.iter().map(|t| t.fold_with(folder)).collect()
 398     }
 399
 400     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 401         self.iter().any(|t| t.visit_with(visitor))
 402     }
 403 }
 404
 405 impl<'tcx, T:TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
 406     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 407         ty::Binder(self.0.fold_with(folder))
 408     }
 409
 410     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 411         folder.fold_binder(self)
 412     }
 413
 414     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 415         self.0.visit_with(visitor)
 416     }
 417
 418     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 419         visitor.visit_binder(self)
 420     }
 421 }
 422
 423 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Slice<ty::ExistentialPredicate<'tcx>> {
 424     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 425         let v = self.iter().map(|p| p.fold_with(folder)).collect::<AccumulateVec<[_; 8]>>();
 426         folder.tcx().intern_existential_predicates(&v)
 427     }
 428
 429     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 430         self.iter().any(|p| p.visit_with(visitor))
 431     }
 432 }
 433
 434 impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialPredicate<'tcx> {
 435     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self  {
 436         use ty::ExistentialPredicate::*;
 437         match *self {
 438             Trait(ref tr) => Trait(tr.fold_with(folder)),
 439             Projection(ref p) => Projection(p.fold_with(folder)),
 440             AutoTrait(did) => AutoTrait(did),
 441         }
 442     }
 443
 444     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 445         match *self {
 446             ty::ExistentialPredicate::Trait(ref tr) => tr.visit_with(visitor),
 447             ty::ExistentialPredicate::Projection(ref p) => p.visit_with(visitor),
 448             ty::ExistentialPredicate::AutoTrait(_) => false,
 449         }
 450     }
 451 }
 452
 453 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Slice<Ty<'tcx>> {
 454     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 455         let v = self.iter().map(|t| t.fold_with(folder)).collect::<AccumulateVec<[_; 8]>>();
 456         folder.tcx().intern_type_list(&v)
 457     }
 458
 459     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 460         self.iter().any(|t| t.visit_with(visitor))
 461     }
 462 }
 463
 464 impl<'tcx> TypeFoldable<'tcx> for Ty<'tcx> {
 465     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 466         let sty = match self.sty {
 467             ty::TyRawPtr(tm) => ty::TyRawPtr(tm.fold_with(folder)),
 468             ty::TyArray(typ, sz) => ty::TyArray(typ.fold_with(folder), sz),
 469             ty::TySlice(typ) => ty::TySlice(typ.fold_with(folder)),
 470             ty::TyAdt(tid, substs) => ty::TyAdt(tid, substs.fold_with(folder)),
 471             ty::TyDynamic(ref trait_ty, ref region) =>
 472                 ty::TyDynamic(trait_ty.fold_with(folder), region.fold_with(folder)),
 473             ty::TyTuple(ts, defaulted) => ty::TyTuple(ts.fold_with(folder), defaulted),
 474             ty::TyFnDef(def_id, substs, f) => {
 475                 ty::TyFnDef(def_id,
 476                             substs.fold_with(folder),
 477                             f.fold_with(folder))
 478             }
 479             ty::TyFnPtr(f) => ty::TyFnPtr(f.fold_with(folder)),
 480             ty::TyRef(ref r, tm) => {
 481                 ty::TyRef(r.fold_with(folder), tm.fold_with(folder))
 482             }
 483             ty::TyClosure(did, substs) => ty::TyClosure(did, substs.fold_with(folder)),
 484             ty::TyProjection(ref data) => ty::TyProjection(data.fold_with(folder)),
 485             ty::TyAnon(did, substs) => ty::TyAnon(did, substs.fold_with(folder)),
 486             ty::TyBool | ty::TyChar | ty::TyStr | ty::TyInt(_) |
 487             ty::TyUint(_) | ty::TyFloat(_) | ty::TyError | ty::TyInfer(_) |
 488             ty::TyParam(..) | ty::TyNever => return self
 489         };
 490
 491         if self.sty == sty {
 492             self
 493         } else {
 494             folder.tcx().mk_ty(sty)
 495         }
 496     }
 497
 498     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 499         folder.fold_ty(*self)
 500     }
 501
 502     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 503         match self.sty {
 504             ty::TyRawPtr(ref tm) => tm.visit_with(visitor),
 505             ty::TyArray(typ, _sz) => typ.visit_with(visitor),
 506             ty::TySlice(typ) => typ.visit_with(visitor),
 507             ty::TyAdt(_, substs) => substs.visit_with(visitor),
 508             ty::TyDynamic(ref trait_ty, ref reg) =>
 509                 trait_ty.visit_with(visitor) || reg.visit_with(visitor),
 510             ty::TyTuple(ts, _) => ts.visit_with(visitor),
 511             ty::TyFnDef(_, substs, ref f) => {
 512                 substs.visit_with(visitor) || f.visit_with(visitor)
 513             }
 514             ty::TyFnPtr(ref f) => f.visit_with(visitor),
 515             ty::TyRef(r, ref tm) => r.visit_with(visitor) || tm.visit_with(visitor),
 516             ty::TyClosure(_did, ref substs) => substs.visit_with(visitor),
 517             ty::TyProjection(ref data) => data.visit_with(visitor),
 518             ty::TyAnon(_, ref substs) => substs.visit_with(visitor),
 519             ty::TyBool | ty::TyChar | ty::TyStr | ty::TyInt(_) |
 520             ty::TyUint(_) | ty::TyFloat(_) | ty::TyError | ty::TyInfer(_) |
 521             ty::TyParam(..) | ty::TyNever => false,
 522         }
 523     }
 524
 525     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 526         visitor.visit_ty(self)
 527     }
 528 }
 529
 530 impl<'tcx> TypeFoldable<'tcx> for ty::TypeAndMut<'tcx> {
 531     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 532         ty::TypeAndMut { ty: self.ty.fold_with(folder), mutbl: self.mutbl }
 533     }
 534
 535     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 536         folder.fold_mt(self)
 537     }
 538
 539     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 540         self.ty.visit_with(visitor)
 541     }
 542 }
 543
 544 impl<'tcx> TypeFoldable<'tcx> for ty::FnSig<'tcx> {
 545     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 546         let inputs_and_output = self.inputs_and_output.fold_with(folder);
 547         ty::FnSig {
 548             inputs_and_output: folder.tcx().intern_type_list(&inputs_and_output),
 549             variadic: self.variadic,
 550             unsafety: self.unsafety,
 551             abi: self.abi,
 552         }
 553     }
 554
 555     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 556         folder.fold_fn_sig(self)
 557     }
 558
 559     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 560         self.inputs().iter().any(|i| i.visit_with(visitor)) ||
 561         self.output().visit_with(visitor)
 562     }
 563 }
 564
 565 impl<'tcx> TypeFoldable<'tcx> for ty::TraitRef<'tcx> {
 566     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 567         ty::TraitRef {
 568             def_id: self.def_id,
 569             substs: self.substs.fold_with(folder),
 570         }
 571     }
 572
 573     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 574         self.substs.visit_with(visitor)
 575     }
 576
 577     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 578         visitor.visit_trait_ref(*self)
 579     }
 580 }
 581
 582 impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialTraitRef<'tcx> {
 583     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 584         ty::ExistentialTraitRef {
 585             def_id: self.def_id,
 586             substs: self.substs.fold_with(folder),
 587         }
 588     }
 589
 590     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 591         self.substs.visit_with(visitor)
 592     }
 593 }
 594
 595 impl<'tcx> TypeFoldable<'tcx> for ty::ImplHeader<'tcx> {
 596     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 597         ty::ImplHeader {
 598             impl_def_id: self.impl_def_id,
 599             self_ty: self.self_ty.fold_with(folder),
 600             trait_ref: self.trait_ref.map(|t| t.fold_with(folder)),
 601             predicates: self.predicates.iter().map(|p| p.fold_with(folder)).collect(),
 602         }
 603     }
 604
 605     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 606         folder.fold_impl_header(self)
 607     }
 608
 609     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 610         self.self_ty.visit_with(visitor) ||
 611             self.trait_ref.map(|r| r.visit_with(visitor)).unwrap_or(false) ||
 612             self.predicates.iter().any(|p| p.visit_with(visitor))
 613     }
 614 }
 615
 616 impl<'tcx> TypeFoldable<'tcx> for ty::Region<'tcx> {
 617     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _folder: &mut F) -> Self {
 618         *self
 619     }
 620
 621     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 622         folder.fold_region(*self)
 623     }
 624
 625     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
 626         false
 627     }
 628
 629     fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 630         visitor.visit_region(*self)
 631     }
 632 }
 633
 634 impl<'tcx> TypeFoldable<'tcx> for ty::ClosureSubsts<'tcx> {
 635     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 636         ty::ClosureSubsts {
 637             substs: self.substs.fold_with(folder),
 638         }
 639     }
 640
 641     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 642         self.substs.visit_with(visitor)
 643     }
 644 }
 645
 646 impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::AutoBorrow<'tcx> {
 647     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 648         match *self {
 649             ty::adjustment::AutoBorrow::Ref(ref r, m) => {
 650                 ty::adjustment::AutoBorrow::Ref(r.fold_with(folder), m)
 651             }
 652             ty::adjustment::AutoBorrow::RawPtr(m) => ty::adjustment::AutoBorrow::RawPtr(m)
 653         }
 654     }
 655
 656     fn fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 657         folder.fold_autoref(self)
 658     }
 659
 660     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 661         match *self {
 662             ty::adjustment::AutoBorrow::Ref(r, _m) => r.visit_with(visitor),
 663             ty::adjustment::AutoBorrow::RawPtr(_m) => false,
 664         }
 665     }
 666 }
 667
 668 impl<'tcx> TypeFoldable<'tcx> for ty::GenericPredicates<'tcx> {
 669     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 670         ty::GenericPredicates {
 671             parent: self.parent,
 672             predicates: self.predicates.fold_with(folder),
 673         }
 674     }
 675
 676     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 677         self.predicates.visit_with(visitor)
 678     }
 679 }
 680
 681 impl<'tcx> TypeFoldable<'tcx> for ty::Predicate<'tcx> {
 682     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 683         match *self {
 684             ty::Predicate::Trait(ref a) =>
 685                 ty::Predicate::Trait(a.fold_with(folder)),
 686             ty::Predicate::Equate(ref binder) =>
 687                 ty::Predicate::Equate(binder.fold_with(folder)),
 688             ty::Predicate::Subtype(ref binder) =>
 689                 ty::Predicate::Subtype(binder.fold_with(folder)),
 690             ty::Predicate::RegionOutlives(ref binder) =>
 691                 ty::Predicate::RegionOutlives(binder.fold_with(folder)),
 692             ty::Predicate::TypeOutlives(ref binder) =>
 693                 ty::Predicate::TypeOutlives(binder.fold_with(folder)),
 694             ty::Predicate::Projection(ref binder) =>
 695                 ty::Predicate::Projection(binder.fold_with(folder)),
 696             ty::Predicate::WellFormed(data) =>
 697                 ty::Predicate::WellFormed(data.fold_with(folder)),
 698             ty::Predicate::ClosureKind(closure_def_id, kind) =>
 699                 ty::Predicate::ClosureKind(closure_def_id, kind),
 700             ty::Predicate::ObjectSafe(trait_def_id) =>
 701                 ty::Predicate::ObjectSafe(trait_def_id),
 702         }
 703     }
 704
 705     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 706         match *self {
 707             ty::Predicate::Trait(ref a) => a.visit_with(visitor),
 708             ty::Predicate::Equate(ref binder) => binder.visit_with(visitor),
 709             ty::Predicate::Subtype(ref binder) => binder.visit_with(visitor),
 710             ty::Predicate::RegionOutlives(ref binder) => binder.visit_with(visitor),
 711             ty::Predicate::TypeOutlives(ref binder) => binder.visit_with(visitor),
 712             ty::Predicate::Projection(ref binder) => binder.visit_with(visitor),
 713             ty::Predicate::WellFormed(data) => data.visit_with(visitor),
 714             ty::Predicate::ClosureKind(_closure_def_id, _kind) => false,
 715             ty::Predicate::ObjectSafe(_trait_def_id) => false,
 716         }
 717     }
 718 }
 719
 720 impl<'tcx> TypeFoldable<'tcx> for ty::ProjectionPredicate<'tcx> {
 721     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 722         ty::ProjectionPredicate {
 723             projection_ty: self.projection_ty.fold_with(folder),
 724             ty: self.ty.fold_with(folder),
 725         }
 726     }
 727
 728     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 729         self.projection_ty.visit_with(visitor) || self.ty.visit_with(visitor)
 730     }
 731 }
 732
 733 impl<'tcx> TypeFoldable<'tcx> for ty::ExistentialProjection<'tcx> {
 734     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 735         ty::ExistentialProjection {
 736             trait_ref: self.trait_ref.fold_with(folder),
 737             item_name: self.item_name,
 738             ty: self.ty.fold_with(folder),
 739         }
 740     }
 741
 742     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 743         self.trait_ref.visit_with(visitor) || self.ty.visit_with(visitor)
 744     }
 745 }
 746
 747 impl<'tcx> TypeFoldable<'tcx> for ty::ProjectionTy<'tcx> {
 748     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 749         ty::ProjectionTy {
 750             trait_ref: self.trait_ref.fold_with(folder),
 751             item_name: self.item_name,
 752         }
 753     }
 754
 755     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 756         self.trait_ref.visit_with(visitor)
 757     }
 758 }
 759
 760 impl<'tcx> TypeFoldable<'tcx> for ty::InstantiatedPredicates<'tcx> {
 761     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 762         ty::InstantiatedPredicates {
 763             predicates: self.predicates.fold_with(folder),
 764         }
 765     }
 766
 767     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 768         self.predicates.visit_with(visitor)
 769     }
 770 }
 771
 772 impl<'tcx> TypeFoldable<'tcx> for ty::EquatePredicate<'tcx> {
 773     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 774         ty::EquatePredicate(self.0.fold_with(folder), self.1.fold_with(folder))
 775     }
 776
 777     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 778         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 779     }
 780 }
 781
 782 impl<'tcx> TypeFoldable<'tcx> for ty::SubtypePredicate<'tcx> {
 783     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 784         ty::SubtypePredicate {
 785             a_is_expected: self.a_is_expected,
 786             a: self.a.fold_with(folder),
 787             b: self.b.fold_with(folder)
 788         }
 789     }
 790
 791     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 792         self.a.visit_with(visitor) || self.b.visit_with(visitor)
 793     }
 794 }
 795
 796 impl<'tcx> TypeFoldable<'tcx> for ty::TraitPredicate<'tcx> {
 797     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 798         ty::TraitPredicate {
 799             trait_ref: self.trait_ref.fold_with(folder)
 800         }
 801     }
 802
 803     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 804         self.trait_ref.visit_with(visitor)
 805     }
 806 }
 807
 808 impl<'tcx,T,U> TypeFoldable<'tcx> for ty::OutlivesPredicate<T,U>
 809     where T : TypeFoldable<'tcx>,
 810           U : TypeFoldable<'tcx>,
 811 {
 812     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 813         ty::OutlivesPredicate(self.0.fold_with(folder),
 814                               self.1.fold_with(folder))
 815     }
 816
 817     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 818         self.0.visit_with(visitor) || self.1.visit_with(visitor)
 819     }
 820 }
 821
 822 impl<'tcx> TypeFoldable<'tcx> for ty::ClosureUpvar<'tcx> {
 823     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 824         ty::ClosureUpvar {
 825             def: self.def,
 826             span: self.span,
 827             ty: self.ty.fold_with(folder),
 828         }
 829     }
 830
 831     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 832         self.ty.visit_with(visitor)
 833     }
 834 }
 835
 836 impl<'tcx, T: TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::error::ExpectedFound<T> {
 837     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 838         ty::error::ExpectedFound {
 839             expected: self.expected.fold_with(folder),
 840             found: self.found.fold_with(folder),
 841         }
 842     }
 843
 844     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 845         self.expected.visit_with(visitor) || self.found.visit_with(visitor)
 846     }
 847 }
 848
 849 impl<'tcx, T: TypeFoldable<'tcx>, I: Idx> TypeFoldable<'tcx> for IndexVec<I, T> {
 850     fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
 851         self.iter().map(|x| x.fold_with(folder)).collect()
 852     }
 853
 854     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
 855         self.iter().any(|t| t.visit_with(visitor))
 856     }
 857 }