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.
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.
11 //! This module contains TypeVariants and its major components
13 use hir::def_id::DefId;
15 use middle::const_val::ConstVal;
17 use rustc_data_structures::indexed_vec::Idx;
18 use ty::subst::{Substs, Subst};
19 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
24 use std::cmp::Ordering;
26 use syntax::ast::{self, Name};
27 use syntax::symbol::keywords;
34 use self::TypeVariants::*;
36 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
37 pub struct TypeAndMut<'tcx> {
39 pub mutbl: hir::Mutability,
42 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
43 RustcEncodable, RustcDecodable, Copy)]
44 /// A "free" region `fr` can be interpreted as "some region
45 /// at least as big as the scope `fr.scope`".
46 pub struct FreeRegion {
48 pub bound_region: BoundRegion,
51 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
52 RustcEncodable, RustcDecodable, Copy)]
53 pub enum BoundRegion {
54 /// An anonymous region parameter for a given fn (&T)
57 /// Named region parameters for functions (a in &'a T)
59 /// The def-id is needed to distinguish free regions in
60 /// the event of shadowing.
63 /// Fresh bound identifiers created during GLB computations.
66 /// Anonymous region for the implicit env pointer parameter
72 pub fn is_named(&self) -> bool {
74 BoundRegion::BrNamed(..) => true,
80 /// NB: If you change this, you'll probably want to change the corresponding
81 /// AST structure in libsyntax/ast.rs as well.
82 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
83 pub enum TypeVariants<'tcx> {
84 /// The primitive boolean type. Written as `bool`.
87 /// The primitive character type; holds a Unicode scalar value
88 /// (a non-surrogate code point). Written as `char`.
91 /// A primitive signed integer type. For example, `i32`.
94 /// A primitive unsigned integer type. For example, `u32`.
97 /// A primitive floating-point type. For example, `f64`.
98 TyFloat(ast::FloatTy),
100 /// Structures, enumerations and unions.
102 /// Substs here, possibly against intuition, *may* contain `TyParam`s.
103 /// That is, even after substitution it is possible that there are type
104 /// variables. This happens when the `TyAdt` corresponds to an ADT
105 /// definition and not a concrete use of it.
106 TyAdt(&'tcx AdtDef, &'tcx Substs<'tcx>),
110 /// The pointee of a string slice. Written as `str`.
113 /// An array with the given length. Written as `[T; n]`.
114 TyArray(Ty<'tcx>, &'tcx ty::Const<'tcx>),
116 /// The pointee of an array slice. Written as `[T]`.
119 /// A raw pointer. Written as `*mut T` or `*const T`
120 TyRawPtr(TypeAndMut<'tcx>),
122 /// A reference; a pointer with an associated lifetime. Written as
123 /// `&'a mut T` or `&'a T`.
124 TyRef(Region<'tcx>, TypeAndMut<'tcx>),
126 /// The anonymous type of a function declaration/definition. Each
127 /// function has a unique type.
128 TyFnDef(DefId, &'tcx Substs<'tcx>),
130 /// A pointer to a function. Written as `fn() -> i32`.
131 TyFnPtr(PolyFnSig<'tcx>),
133 /// A trait, defined with `trait`.
134 TyDynamic(Binder<&'tcx Slice<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
136 /// The anonymous type of a closure. Used to represent the type of
138 TyClosure(DefId, ClosureSubsts<'tcx>),
140 /// The anonymous type of a generator. Used to represent the type of
142 TyGenerator(DefId, ClosureSubsts<'tcx>, GeneratorInterior<'tcx>),
144 /// The never type `!`
147 /// A tuple type. For example, `(i32, bool)`.
148 /// The bool indicates whether this is a unit tuple and was created by
149 /// defaulting a diverging type variable with feature(never_type) disabled.
150 /// It's only purpose is for raising future-compatibility warnings for when
151 /// diverging type variables start defaulting to ! instead of ().
152 TyTuple(&'tcx Slice<Ty<'tcx>>, bool),
154 /// The projection of an associated type. For example,
155 /// `<T as Trait<..>>::N`.
156 TyProjection(ProjectionTy<'tcx>),
158 /// Anonymized (`impl Trait`) type found in a return type.
159 /// The DefId comes from the `impl Trait` ast::Ty node, and the
160 /// substitutions are for the generics of the function in question.
161 /// After typeck, the concrete type can be found in the `types` map.
162 TyAnon(DefId, &'tcx Substs<'tcx>),
164 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
167 /// A type variable used during type-checking.
170 /// A placeholder for a type which could not be computed; this is
171 /// propagated to avoid useless error messages.
175 /// A closure can be modeled as a struct that looks like:
177 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
185 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
186 /// in scope on the function that defined the closure,
187 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
188 /// is rather hackily encoded via a scalar type. See
189 /// `TyS::to_opt_closure_kind` for details.
190 /// - CS represents the *closure signature*, representing as a `fn()`
191 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
192 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
194 /// - U0...Uk are type parameters representing the types of its upvars
195 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
196 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
198 /// So, for example, given this function:
200 /// fn foo<'a, T>(data: &'a mut T) {
201 /// do(|| data.count += 1)
204 /// the type of the closure would be something like:
206 /// struct Closure<'a, T, U0> {
210 /// Note that the type of the upvar is not specified in the struct.
211 /// You may wonder how the impl would then be able to use the upvar,
212 /// if it doesn't know it's type? The answer is that the impl is
213 /// (conceptually) not fully generic over Closure but rather tied to
214 /// instances with the expected upvar types:
216 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
220 /// You can see that the *impl* fully specified the type of the upvar
221 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
222 /// (Here, I am assuming that `data` is mut-borrowed.)
224 /// Now, the last question you may ask is: Why include the upvar types
225 /// as extra type parameters? The reason for this design is that the
226 /// upvar types can reference lifetimes that are internal to the
227 /// creating function. In my example above, for example, the lifetime
228 /// `'b` represents the scope of the closure itself; this is some
229 /// subset of `foo`, probably just the scope of the call to the to
230 /// `do()`. If we just had the lifetime/type parameters from the
231 /// enclosing function, we couldn't name this lifetime `'b`. Note that
232 /// there can also be lifetimes in the types of the upvars themselves,
233 /// if one of them happens to be a reference to something that the
234 /// creating fn owns.
236 /// OK, you say, so why not create a more minimal set of parameters
237 /// that just includes the extra lifetime parameters? The answer is
238 /// primarily that it would be hard --- we don't know at the time when
239 /// we create the closure type what the full types of the upvars are,
240 /// nor do we know which are borrowed and which are not. In this
241 /// design, we can just supply a fresh type parameter and figure that
244 /// All right, you say, but why include the type parameters from the
245 /// original function then? The answer is that trans may need them
246 /// when monomorphizing, and they may not appear in the upvars. A
247 /// closure could capture no variables but still make use of some
248 /// in-scope type parameter with a bound (e.g., if our example above
249 /// had an extra `U: Default`, and the closure called `U::default()`).
251 /// There is another reason. This design (implicitly) prohibits
252 /// closures from capturing themselves (except via a trait
253 /// object). This simplifies closure inference considerably, since it
254 /// means that when we infer the kind of a closure or its upvars, we
255 /// don't have to handle cycles where the decisions we make for
256 /// closure C wind up influencing the decisions we ought to make for
257 /// closure C (which would then require fixed point iteration to
258 /// handle). Plus it fixes an ICE. :P
262 /// Perhaps surprisingly, `ClosureSubsts` are also used for
263 /// generators. In that case, what is written above is only half-true
264 /// -- the set of type parameters is similar, but the role of CK and
265 /// CS are different. CK represents the "yield type" and CS
266 /// represents the "return type" of the generator.
268 /// It'd be nice to split this struct into ClosureSubsts and
269 /// GeneratorSubsts, I believe. -nmatsakis
270 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
271 pub struct ClosureSubsts<'tcx> {
272 /// Lifetime and type parameters from the enclosing function,
273 /// concatenated with the types of the upvars.
275 /// These are separated out because trans wants to pass them around
276 /// when monomorphizing.
277 pub substs: &'tcx Substs<'tcx>,
280 /// Struct returned by `split()`. Note that these are subslices of the
281 /// parent slice and not canonical substs themselves.
282 struct SplitClosureSubsts<'tcx> {
283 closure_kind_ty: Ty<'tcx>,
284 closure_sig_ty: Ty<'tcx>,
285 upvar_kinds: &'tcx [Kind<'tcx>],
288 impl<'tcx> ClosureSubsts<'tcx> {
289 /// Divides the closure substs into their respective
290 /// components. Single source of truth with respect to the
292 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
293 let generics = tcx.generics_of(def_id);
294 let parent_len = generics.parent_count();
296 closure_kind_ty: self.substs[parent_len].as_type().expect("CK should be a type"),
297 closure_sig_ty: self.substs[parent_len + 1].as_type().expect("CS should be a type"),
298 upvar_kinds: &self.substs[parent_len + 2..],
303 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
304 impl Iterator<Item=Ty<'tcx>> + 'tcx
306 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
307 upvar_kinds.iter().map(|t| t.as_type().expect("upvar should be type"))
310 /// Returns the closure kind for this closure; may return a type
311 /// variable during inference. To get the closure kind during
312 /// inference, use `infcx.closure_kind(def_id, substs)`.
313 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
314 self.split(def_id, tcx).closure_kind_ty
317 /// Returns the type representing the closure signature for this
318 /// closure; may contain type variables during inference. To get
319 /// the closure signature during inference, use
320 /// `infcx.fn_sig(def_id)`.
321 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
322 self.split(def_id, tcx).closure_sig_ty
325 /// Returns the type representing the yield type of the generator.
326 pub fn generator_yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
327 self.closure_kind_ty(def_id, tcx)
330 /// Returns the type representing the return type of the generator.
331 pub fn generator_return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
332 self.closure_sig_ty(def_id, tcx)
335 /// Return the "generator signature", which consists of its yield
336 /// and return types.
338 /// NB. Some bits of the code prefers to see this wrapped in a
339 /// binder, but it never contains bound regions. Probably this
340 /// function should be removed.
341 pub fn generator_poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
342 ty::Binder(self.generator_sig(def_id, tcx))
345 /// Return the "generator signature", which consists of its yield
346 /// and return types.
347 pub fn generator_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
349 yield_ty: self.generator_yield_ty(def_id, tcx),
350 return_ty: self.generator_return_ty(def_id, tcx),
355 impl<'tcx> ClosureSubsts<'tcx> {
356 /// Returns the closure kind for this closure; only usable outside
357 /// of an inference context, because in that context we know that
358 /// there are no type variables.
359 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
360 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
363 /// Extracts the signature from the closure; only usable outside
364 /// of an inference context, because in that context we know that
365 /// there are no type variables.
366 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
367 match self.closure_sig_ty(def_id, tcx).sty {
368 ty::TyFnPtr(sig) => sig,
369 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
374 impl<'a, 'gcx, 'tcx> ClosureSubsts<'tcx> {
375 /// This returns the types of the MIR locals which had to be stored across suspension points.
376 /// It is calculated in rustc_mir::transform::generator::StateTransform.
377 /// All the types here must be in the tuple in GeneratorInterior.
378 pub fn state_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
379 impl Iterator<Item=Ty<'tcx>> + 'a
381 let state = tcx.generator_layout(def_id).fields.iter();
382 state.map(move |d| d.ty.subst(tcx, self.substs))
385 /// This is the types of all the fields stored in a generator.
386 /// It includes the upvars, state types and the state discriminant which is u32.
387 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
388 impl Iterator<Item=Ty<'tcx>> + 'a
390 let upvars = self.upvar_tys(def_id, tcx);
391 let state = self.state_tys(def_id, tcx);
392 upvars.chain(iter::once(tcx.types.u32)).chain(state)
396 /// This describes the types that can be contained in a generator.
397 /// It will be a type variable initially and unified in the last stages of typeck of a body.
398 /// It contains a tuple of all the types that could end up on a generator frame.
399 /// The state transformation MIR pass may only produce layouts which mention types in this tuple.
400 /// Upvars are not counted here.
401 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
402 pub struct GeneratorInterior<'tcx> {
403 pub witness: Ty<'tcx>,
406 impl<'tcx> GeneratorInterior<'tcx> {
407 pub fn new(witness: Ty<'tcx>) -> GeneratorInterior<'tcx> {
408 GeneratorInterior { witness }
411 pub fn as_slice(&self) -> &'tcx Slice<Ty<'tcx>> {
412 match self.witness.sty {
413 ty::TyTuple(s, _) => s,
419 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
420 pub enum ExistentialPredicate<'tcx> {
422 Trait(ExistentialTraitRef<'tcx>),
423 /// e.g. Iterator::Item = T
424 Projection(ExistentialProjection<'tcx>),
429 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
430 pub fn cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
431 use self::ExistentialPredicate::*;
432 match (*self, *other) {
433 (Trait(_), Trait(_)) => Ordering::Equal,
434 (Projection(ref a), Projection(ref b)) =>
435 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
436 (AutoTrait(ref a), AutoTrait(ref b)) =>
437 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
438 (Trait(_), _) => Ordering::Less,
439 (Projection(_), Trait(_)) => Ordering::Greater,
440 (Projection(_), _) => Ordering::Less,
441 (AutoTrait(_), _) => Ordering::Greater,
447 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
448 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
449 -> ty::Predicate<'tcx> {
451 match *self.skip_binder() {
452 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
453 ExistentialPredicate::Projection(p) =>
454 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
455 ExistentialPredicate::AutoTrait(did) => {
456 let trait_ref = Binder(ty::TraitRef {
458 substs: tcx.mk_substs_trait(self_ty, &[]),
460 trait_ref.to_predicate()
466 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<ExistentialPredicate<'tcx>> {}
468 impl<'tcx> Slice<ExistentialPredicate<'tcx>> {
469 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
471 Some(&ExistentialPredicate::Trait(tr)) => Some(tr),
477 pub fn projection_bounds<'a>(&'a self) ->
478 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
479 self.iter().filter_map(|predicate| {
481 ExistentialPredicate::Projection(p) => Some(p),
488 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
489 self.iter().filter_map(|predicate| {
491 ExistentialPredicate::AutoTrait(d) => Some(d),
498 impl<'tcx> Binder<&'tcx Slice<ExistentialPredicate<'tcx>>> {
499 pub fn principal(&self) -> Option<PolyExistentialTraitRef<'tcx>> {
500 self.skip_binder().principal().map(Binder)
504 pub fn projection_bounds<'a>(&'a self) ->
505 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
506 self.skip_binder().projection_bounds().map(Binder)
510 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
511 self.skip_binder().auto_traits()
514 pub fn iter<'a>(&'a self)
515 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
516 self.skip_binder().iter().cloned().map(Binder)
520 /// A complete reference to a trait. These take numerous guises in syntax,
521 /// but perhaps the most recognizable form is in a where clause:
525 /// This would be represented by a trait-reference where the def-id is the
526 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
527 /// and `U` as parameter 1.
529 /// Trait references also appear in object types like `Foo<U>`, but in
530 /// that case the `Self` parameter is absent from the substitutions.
532 /// Note that a `TraitRef` introduces a level of region binding, to
533 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
534 /// U>` or higher-ranked object types.
535 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
536 pub struct TraitRef<'tcx> {
538 pub substs: &'tcx Substs<'tcx>,
541 impl<'tcx> TraitRef<'tcx> {
542 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
543 TraitRef { def_id: def_id, substs: substs }
546 pub fn self_ty(&self) -> Ty<'tcx> {
547 self.substs.type_at(0)
550 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
551 // Select only the "input types" from a trait-reference. For
552 // now this is all the types that appear in the
553 // trait-reference, but it should eventually exclude
559 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
561 impl<'tcx> PolyTraitRef<'tcx> {
562 pub fn self_ty(&self) -> Ty<'tcx> {
566 pub fn def_id(&self) -> DefId {
570 pub fn substs(&self) -> &'tcx Substs<'tcx> {
571 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
575 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
576 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
580 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
581 // Note that we preserve binding levels
582 Binder(ty::TraitPredicate { trait_ref: self.0.clone() })
586 /// An existential reference to a trait, where `Self` is erased.
587 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
589 /// exists T. T: Trait<'a, 'b, X, Y>
591 /// The substitutions don't include the erased `Self`, only trait
592 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
593 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
594 pub struct ExistentialTraitRef<'tcx> {
596 pub substs: &'tcx Substs<'tcx>,
599 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
600 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
601 // Select only the "input types" from a trait-reference. For
602 // now this is all the types that appear in the
603 // trait-reference, but it should eventually exclude
608 /// Object types don't have a self-type specified. Therefore, when
609 /// we convert the principal trait-ref into a normal trait-ref,
610 /// you must give *some* self-type. A common choice is `mk_err()`
611 /// or some skolemized type.
612 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
613 -> ty::TraitRef<'tcx> {
614 // otherwise the escaping regions would be captured by the binder
615 assert!(!self_ty.has_escaping_regions());
619 substs: tcx.mk_substs(
620 iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned()))
625 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
627 impl<'tcx> PolyExistentialTraitRef<'tcx> {
628 pub fn def_id(&self) -> DefId {
632 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
633 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
638 /// Binder is a binder for higher-ranked lifetimes. It is part of the
639 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
640 /// (which would be represented by the type `PolyTraitRef ==
641 /// Binder<TraitRef>`). Note that when we skolemize, instantiate,
642 /// erase, or otherwise "discharge" these bound regions, we change the
643 /// type from `Binder<T>` to just `T` (see
644 /// e.g. `liberate_late_bound_regions`).
645 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
646 pub struct Binder<T>(pub T);
649 /// Skips the binder and returns the "bound" value. This is a
650 /// risky thing to do because it's easy to get confused about
651 /// debruijn indices and the like. It is usually better to
652 /// discharge the binder using `no_late_bound_regions` or
653 /// `replace_late_bound_regions` or something like
654 /// that. `skip_binder` is only valid when you are either
655 /// extracting data that has nothing to do with bound regions, you
656 /// are doing some sort of test that does not involve bound
657 /// regions, or you are being very careful about your depth
660 /// Some examples where `skip_binder` is reasonable:
661 /// - extracting the def-id from a PolyTraitRef;
662 /// - comparing the self type of a PolyTraitRef to see if it is equal to
663 /// a type parameter `X`, since the type `X` does not reference any regions
664 pub fn skip_binder(&self) -> &T {
668 pub fn as_ref(&self) -> Binder<&T> {
672 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
673 where F: FnOnce(&T) -> U
675 self.as_ref().map_bound(f)
678 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
679 where F: FnOnce(T) -> U
681 ty::Binder(f(self.0))
685 /// Represents the projection of an associated type. In explicit UFCS
686 /// form this would be written `<T as Trait<..>>::N`.
687 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
688 pub struct ProjectionTy<'tcx> {
689 /// The parameters of the associated item.
690 pub substs: &'tcx Substs<'tcx>,
692 /// The DefId of the TraitItem for the associated type N.
694 /// Note that this is not the DefId of the TraitRef containing this
695 /// associated type, which is in tcx.associated_item(item_def_id).container.
696 pub item_def_id: DefId,
699 impl<'a, 'tcx> ProjectionTy<'tcx> {
700 /// Construct a ProjectionTy by searching the trait from trait_ref for the
701 /// associated item named item_name.
702 pub fn from_ref_and_name(
703 tcx: TyCtxt, trait_ref: ty::TraitRef<'tcx>, item_name: Name
704 ) -> ProjectionTy<'tcx> {
705 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
706 item.kind == ty::AssociatedKind::Type &&
707 tcx.hygienic_eq(item_name, item.name, trait_ref.def_id)
711 substs: trait_ref.substs,
716 /// Extracts the underlying trait reference from this projection.
717 /// For example, if this is a projection of `<T as Iterator>::Item`,
718 /// then this function would return a `T: Iterator` trait reference.
719 pub fn trait_ref(&self, tcx: TyCtxt) -> ty::TraitRef<'tcx> {
720 let def_id = tcx.associated_item(self.item_def_id).container.id();
727 pub fn self_ty(&self) -> Ty<'tcx> {
728 self.substs.type_at(0)
732 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
733 pub struct GenSig<'tcx> {
734 pub yield_ty: Ty<'tcx>,
735 pub return_ty: Ty<'tcx>,
738 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
740 impl<'tcx> PolyGenSig<'tcx> {
741 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
742 self.map_bound_ref(|sig| sig.yield_ty)
744 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
745 self.map_bound_ref(|sig| sig.return_ty)
749 /// Signature of a function type, which I have arbitrarily
750 /// decided to use to refer to the input/output types.
752 /// - `inputs` is the list of arguments and their modes.
753 /// - `output` is the return type.
754 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
755 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
756 pub struct FnSig<'tcx> {
757 pub inputs_and_output: &'tcx Slice<Ty<'tcx>>,
759 pub unsafety: hir::Unsafety,
763 impl<'tcx> FnSig<'tcx> {
764 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
765 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
768 pub fn output(&self) -> Ty<'tcx> {
769 self.inputs_and_output[self.inputs_and_output.len() - 1]
773 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
775 impl<'tcx> PolyFnSig<'tcx> {
776 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
777 Binder(self.skip_binder().inputs())
779 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
780 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
782 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
783 self.map_bound_ref(|fn_sig| fn_sig.output().clone())
785 pub fn variadic(&self) -> bool {
786 self.skip_binder().variadic
788 pub fn unsafety(&self) -> hir::Unsafety {
789 self.skip_binder().unsafety
791 pub fn abi(&self) -> abi::Abi {
792 self.skip_binder().abi
796 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
802 impl<'a, 'gcx, 'tcx> ParamTy {
803 pub fn new(index: u32, name: Name) -> ParamTy {
804 ParamTy { idx: index, name: name }
807 pub fn for_self() -> ParamTy {
808 ParamTy::new(0, keywords::SelfType.name())
811 pub fn for_def(def: &ty::TypeParameterDef) -> ParamTy {
812 ParamTy::new(def.index, def.name)
815 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
816 tcx.mk_param(self.idx, self.name)
819 pub fn is_self(&self) -> bool {
820 if self.name == keywords::SelfType.name() {
821 assert_eq!(self.idx, 0);
829 /// A [De Bruijn index][dbi] is a standard means of representing
830 /// regions (and perhaps later types) in a higher-ranked setting. In
831 /// particular, imagine a type like this:
833 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
836 /// | +------------+ 1 | |
838 /// +--------------------------------+ 2 |
840 /// +------------------------------------------+ 1
842 /// In this type, there are two binders (the outer fn and the inner
843 /// fn). We need to be able to determine, for any given region, which
844 /// fn type it is bound by, the inner or the outer one. There are
845 /// various ways you can do this, but a De Bruijn index is one of the
846 /// more convenient and has some nice properties. The basic idea is to
847 /// count the number of binders, inside out. Some examples should help
848 /// clarify what I mean.
850 /// Let's start with the reference type `&'b isize` that is the first
851 /// argument to the inner function. This region `'b` is assigned a De
852 /// Bruijn index of 1, meaning "the innermost binder" (in this case, a
853 /// fn). The region `'a` that appears in the second argument type (`&'a
854 /// isize`) would then be assigned a De Bruijn index of 2, meaning "the
855 /// second-innermost binder". (These indices are written on the arrays
858 /// What is interesting is that De Bruijn index attached to a particular
859 /// variable will vary depending on where it appears. For example,
860 /// the final type `&'a char` also refers to the region `'a` declared on
861 /// the outermost fn. But this time, this reference is not nested within
862 /// any other binders (i.e., it is not an argument to the inner fn, but
863 /// rather the outer one). Therefore, in this case, it is assigned a
864 /// De Bruijn index of 1, because the innermost binder in that location
867 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
868 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, Copy, PartialOrd, Ord)]
869 pub struct DebruijnIndex {
870 /// We maintain the invariant that this is never 0. So 1 indicates
871 /// the innermost binder. To ensure this, create with `DebruijnIndex::new`.
875 pub type Region<'tcx> = &'tcx RegionKind;
877 /// Representation of regions.
879 /// Unlike types, most region variants are "fictitious", not concrete,
880 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
881 /// ones representing concrete regions.
885 /// These are regions that are stored behind a binder and must be substituted
886 /// with some concrete region before being used. There are 2 kind of
887 /// bound regions: early-bound, which are bound in an item's Generics,
888 /// and are substituted by a Substs, and late-bound, which are part of
889 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
890 /// the likes of `liberate_late_bound_regions`. The distinction exists
891 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
893 /// Unlike TyParam-s, bound regions are not supposed to exist "in the wild"
894 /// outside their binder, e.g. in types passed to type inference, and
895 /// should first be substituted (by skolemized regions, free regions,
896 /// or region variables).
898 /// ## Skolemized and Free Regions
900 /// One often wants to work with bound regions without knowing their precise
901 /// identity. For example, when checking a function, the lifetime of a borrow
902 /// can end up being assigned to some region parameter. In these cases,
903 /// it must be ensured that bounds on the region can't be accidentally
904 /// assumed without being checked.
906 /// The process of doing that is called "skolemization". The bound regions
907 /// are replaced by skolemized markers, which don't satisfy any relation
908 /// not explicitly provided.
910 /// There are 2 kinds of skolemized regions in rustc: `ReFree` and
911 /// `ReSkolemized`. When checking an item's body, `ReFree` is supposed
912 /// to be used. These also support explicit bounds: both the internally-stored
913 /// *scope*, which the region is assumed to outlive, as well as other
914 /// relations stored in the `FreeRegionMap`. Note that these relations
915 /// aren't checked when you `make_subregion` (or `eq_types`), only by
916 /// `resolve_regions_and_report_errors`.
918 /// When working with higher-ranked types, some region relations aren't
919 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
920 /// `ReSkolemized` is designed for this purpose. In these contexts,
921 /// there's also the risk that some inference variable laying around will
922 /// get unified with your skolemized region: if you want to check whether
923 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
924 /// with a skolemized region `'%a`, the variable `'_` would just be
925 /// instantiated to the skolemized region `'%a`, which is wrong because
926 /// the inference variable is supposed to satisfy the relation
927 /// *for every value of the skolemized region*. To ensure that doesn't
928 /// happen, you can use `leak_check`. This is more clearly explained
929 /// by infer/higher_ranked/README.md.
931 /// [1] http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
932 /// [2] http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
933 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
934 pub enum RegionKind {
935 // Region bound in a type or fn declaration which will be
936 // substituted 'early' -- that is, at the same time when type
937 // parameters are substituted.
938 ReEarlyBound(EarlyBoundRegion),
940 // Region bound in a function scope, which will be substituted when the
941 // function is called.
942 ReLateBound(DebruijnIndex, BoundRegion),
944 /// When checking a function body, the types of all arguments and so forth
945 /// that refer to bound region parameters are modified to refer to free
946 /// region parameters.
949 /// A concrete region naming some statically determined scope
950 /// (e.g. an expression or sequence of statements) within the
951 /// current function.
952 ReScope(region::Scope),
954 /// Static data that has an "infinite" lifetime. Top in the region lattice.
957 /// A region variable. Should not exist after typeck.
960 /// A skolemized region - basically the higher-ranked version of ReFree.
961 /// Should not exist after typeck.
962 ReSkolemized(SkolemizedRegionVid, BoundRegion),
964 /// Empty lifetime is for data that is never accessed.
965 /// Bottom in the region lattice. We treat ReEmpty somewhat
966 /// specially; at least right now, we do not generate instances of
967 /// it during the GLB computations, but rather
968 /// generate an error instead. This is to improve error messages.
969 /// The only way to get an instance of ReEmpty is to have a region
970 /// variable with no constraints.
973 /// Erased region, used by trait selection, in MIR and during trans.
977 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
979 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
980 pub struct EarlyBoundRegion {
986 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
991 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
996 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
997 pub struct FloatVid {
1001 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy, PartialOrd, Ord)]
1002 pub struct RegionVid {
1006 // FIXME: We could convert this to use `newtype_index!`
1007 impl Idx for RegionVid {
1008 fn new(value: usize) -> Self {
1009 assert!(value < ::std::u32::MAX as usize);
1010 RegionVid { index: value as u32 }
1013 fn index(self) -> usize {
1018 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1019 pub struct SkolemizedRegionVid {
1023 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1029 /// A `FreshTy` is one that is generated as a replacement for an
1030 /// unbound type variable. This is convenient for caching etc. See
1031 /// `infer::freshen` for more details.
1037 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1038 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1039 pub struct ExistentialProjection<'tcx> {
1040 pub item_def_id: DefId,
1041 pub substs: &'tcx Substs<'tcx>,
1045 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1047 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1048 /// Extracts the underlying existential trait reference from this projection.
1049 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1050 /// then this function would return a `exists T. T: Iterator` existential trait
1052 pub fn trait_ref(&self, tcx: TyCtxt) -> ty::ExistentialTraitRef<'tcx> {
1053 let def_id = tcx.associated_item(self.item_def_id).container.id();
1054 ty::ExistentialTraitRef{
1056 substs: self.substs,
1060 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1062 -> ty::ProjectionPredicate<'tcx>
1064 // otherwise the escaping regions would be captured by the binders
1065 assert!(!self_ty.has_escaping_regions());
1067 ty::ProjectionPredicate {
1068 projection_ty: ty::ProjectionTy {
1069 item_def_id: self.item_def_id,
1070 substs: tcx.mk_substs(
1071 iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned())),
1078 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1079 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1080 -> ty::PolyProjectionPredicate<'tcx> {
1081 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1085 impl DebruijnIndex {
1086 pub fn new(depth: u32) -> DebruijnIndex {
1088 DebruijnIndex { depth: depth }
1091 pub fn shifted(&self, amount: u32) -> DebruijnIndex {
1092 DebruijnIndex { depth: self.depth + amount }
1096 /// Region utilities
1098 pub fn is_late_bound(&self) -> bool {
1100 ty::ReLateBound(..) => true,
1105 pub fn needs_infer(&self) -> bool {
1107 ty::ReVar(..) | ty::ReSkolemized(..) => true,
1112 pub fn escapes_depth(&self, depth: u32) -> bool {
1114 ty::ReLateBound(debruijn, _) => debruijn.depth > depth,
1119 /// Returns the depth of `self` from the (1-based) binding level `depth`
1120 pub fn from_depth(&self, depth: u32) -> RegionKind {
1122 ty::ReLateBound(debruijn, r) => ty::ReLateBound(DebruijnIndex {
1123 depth: debruijn.depth - (depth - 1)
1129 pub fn type_flags(&self) -> TypeFlags {
1130 let mut flags = TypeFlags::empty();
1134 flags = flags | TypeFlags::HAS_RE_INFER;
1135 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1137 ty::ReSkolemized(..) => {
1138 flags = flags | TypeFlags::HAS_RE_INFER;
1139 flags = flags | TypeFlags::HAS_RE_SKOL;
1140 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1142 ty::ReLateBound(..) => { }
1143 ty::ReEarlyBound(..) => { flags = flags | TypeFlags::HAS_RE_EARLY_BOUND; }
1144 ty::ReStatic | ty::ReErased => { }
1145 _ => { flags = flags | TypeFlags::HAS_FREE_REGIONS; }
1149 ty::ReStatic | ty::ReEmpty | ty::ReErased => (),
1150 _ => flags = flags | TypeFlags::HAS_LOCAL_NAMES,
1153 debug!("type_flags({:?}) = {:?}", self, flags);
1158 /// Given an early-bound or free region, returns the def-id where it was bound.
1159 /// For example, consider the regions in this snippet of code:
1163 /// ^^ -- early bound, declared on an impl
1165 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1166 /// ^^ ^^ ^ anonymous, late-bound
1167 /// | early-bound, appears in where-clauses
1168 /// late-bound, appears only in fn args
1173 /// Here, `free_region_binding_scope('a)` would return the def-id
1174 /// of the impl, and for all the other highlighted regions, it
1175 /// would return the def-id of the function. In other cases (not shown), this
1176 /// function might return the def-id of a closure.
1177 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1179 ty::ReEarlyBound(br) => {
1180 tcx.parent_def_id(br.def_id).unwrap()
1182 ty::ReFree(fr) => fr.scope,
1183 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1189 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1190 pub fn as_opt_param_ty(&self) -> Option<ty::ParamTy> {
1192 ty::TyParam(ref d) => Some(d.clone()),
1197 pub fn is_nil(&self) -> bool {
1199 TyTuple(ref tys, _) => tys.is_empty(),
1204 pub fn is_never(&self) -> bool {
1211 /// Test whether this is a `()` which was produced by defaulting a
1212 /// diverging type variable with feature(never_type) disabled.
1213 pub fn is_defaulted_unit(&self) -> bool {
1215 TyTuple(_, true) => true,
1220 pub fn is_primitive(&self) -> bool {
1222 TyBool | TyChar | TyInt(_) | TyUint(_) | TyFloat(_) => true,
1227 pub fn is_ty_var(&self) -> bool {
1229 TyInfer(TyVar(_)) => true,
1234 pub fn is_phantom_data(&self) -> bool {
1235 if let TyAdt(def, _) = self.sty {
1236 def.is_phantom_data()
1242 pub fn is_bool(&self) -> bool { self.sty == TyBool }
1244 pub fn is_param(&self, index: u32) -> bool {
1246 ty::TyParam(ref data) => data.idx == index,
1251 pub fn is_self(&self) -> bool {
1253 TyParam(ref p) => p.is_self(),
1258 pub fn is_slice(&self) -> bool {
1260 TyRawPtr(mt) | TyRef(_, mt) => match mt.ty.sty {
1261 TySlice(_) | TyStr => true,
1269 pub fn is_simd(&self) -> bool {
1271 TyAdt(def, _) => def.repr.simd(),
1276 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1278 TyArray(ty, _) | TySlice(ty) => ty,
1279 TyStr => tcx.mk_mach_uint(ast::UintTy::U8),
1280 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1284 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1286 TyAdt(def, substs) => {
1287 def.struct_variant().fields[0].ty(tcx, substs)
1289 _ => bug!("simd_type called on invalid type")
1293 pub fn simd_size(&self, _cx: TyCtxt) -> usize {
1295 TyAdt(def, _) => def.struct_variant().fields.len(),
1296 _ => bug!("simd_size called on invalid type")
1300 pub fn is_region_ptr(&self) -> bool {
1307 pub fn is_mutable_pointer(&self) -> bool {
1309 TyRawPtr(tnm) | TyRef(_, tnm) => if let hir::Mutability::MutMutable = tnm.mutbl {
1318 pub fn is_unsafe_ptr(&self) -> bool {
1320 TyRawPtr(_) => return true,
1325 pub fn is_box(&self) -> bool {
1327 TyAdt(def, _) => def.is_box(),
1332 /// panics if called on any type other than `Box<T>`
1333 pub fn boxed_ty(&self) -> Ty<'tcx> {
1335 TyAdt(def, substs) if def.is_box() => substs.type_at(0),
1336 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1340 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1341 /// (A TyRawPtr is scalar because it represents a non-managed pointer, so its
1342 /// contents are abstract to rustc.)
1343 pub fn is_scalar(&self) -> bool {
1345 TyBool | TyChar | TyInt(_) | TyFloat(_) | TyUint(_) |
1346 TyInfer(IntVar(_)) | TyInfer(FloatVar(_)) |
1347 TyFnDef(..) | TyFnPtr(_) | TyRawPtr(_) => true,
1352 /// Returns true if this type is a floating point type and false otherwise.
1353 pub fn is_floating_point(&self) -> bool {
1356 TyInfer(FloatVar(_)) => true,
1361 pub fn is_trait(&self) -> bool {
1363 TyDynamic(..) => true,
1368 pub fn is_enum(&self) -> bool {
1370 TyAdt(adt_def, _) => {
1377 pub fn is_closure(&self) -> bool {
1379 TyClosure(..) => true,
1384 pub fn is_generator(&self) -> bool {
1386 TyGenerator(..) => true,
1391 pub fn is_integral(&self) -> bool {
1393 TyInfer(IntVar(_)) | TyInt(_) | TyUint(_) => true,
1398 pub fn is_fresh_ty(&self) -> bool {
1400 TyInfer(FreshTy(_)) => true,
1405 pub fn is_fresh(&self) -> bool {
1407 TyInfer(FreshTy(_)) => true,
1408 TyInfer(FreshIntTy(_)) => true,
1409 TyInfer(FreshFloatTy(_)) => true,
1414 pub fn is_uint(&self) -> bool {
1416 TyInfer(IntVar(_)) | TyUint(ast::UintTy::Us) => true,
1421 pub fn is_char(&self) -> bool {
1428 pub fn is_fp(&self) -> bool {
1430 TyInfer(FloatVar(_)) | TyFloat(_) => true,
1435 pub fn is_numeric(&self) -> bool {
1436 self.is_integral() || self.is_fp()
1439 pub fn is_signed(&self) -> bool {
1446 pub fn is_machine(&self) -> bool {
1448 TyInt(ast::IntTy::Is) | TyUint(ast::UintTy::Us) => false,
1449 TyInt(..) | TyUint(..) | TyFloat(..) => true,
1454 pub fn has_concrete_skeleton(&self) -> bool {
1456 TyParam(_) | TyInfer(_) | TyError => false,
1461 /// Returns the type and mutability of *ty.
1463 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1464 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1465 pub fn builtin_deref(&self, explicit: bool, pref: ty::LvaluePreference)
1466 -> Option<TypeAndMut<'tcx>>
1469 TyAdt(def, _) if def.is_box() => {
1471 ty: self.boxed_ty(),
1472 mutbl: if pref == ty::PreferMutLvalue {
1479 TyRef(_, mt) => Some(mt),
1480 TyRawPtr(mt) if explicit => Some(mt),
1485 /// Returns the type of ty[i]
1486 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1488 TyArray(ty, _) | TySlice(ty) => Some(ty),
1493 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1495 TyFnDef(def_id, substs) => {
1496 tcx.fn_sig(def_id).subst(tcx, substs)
1499 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1503 pub fn is_fn(&self) -> bool {
1505 TyFnDef(..) | TyFnPtr(_) => true,
1510 pub fn ty_to_def_id(&self) -> Option<DefId> {
1512 TyDynamic(ref tt, ..) => tt.principal().map(|p| p.def_id()),
1513 TyAdt(def, _) => Some(def.did),
1514 TyForeign(did) => Some(did),
1515 TyClosure(id, _) => Some(id),
1520 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1522 TyAdt(adt, _) => Some(adt),
1527 /// Returns the regions directly referenced from this type (but
1528 /// not types reachable from this type via `walk_tys`). This
1529 /// ignores late-bound regions binders.
1530 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1532 TyRef(region, _) => {
1535 TyDynamic(ref obj, region) => {
1536 let mut v = vec![region];
1537 if let Some(p) = obj.principal() {
1538 v.extend(p.skip_binder().substs.regions());
1542 TyAdt(_, substs) | TyAnon(_, substs) => {
1543 substs.regions().collect()
1545 TyClosure(_, ref substs) | TyGenerator(_, ref substs, _) => {
1546 substs.substs.regions().collect()
1548 TyProjection(ref data) => {
1549 data.substs.regions().collect()
1573 /// When we create a closure, we record its kind (i.e., what trait
1574 /// it implements) into its `ClosureSubsts` using a type
1575 /// parameter. This is kind of a phantom type, except that the
1576 /// most convenient thing for us to are the integral types. This
1577 /// function converts such a special type into the closure
1578 /// kind. To go the other way, use
1579 /// `tcx.closure_kind_ty(closure_kind)`.
1581 /// Note that during type checking, we use an inference variable
1582 /// to represent the closure kind, because it has not yet been
1583 /// inferred. Once [upvar inference] is complete, that type varibale
1584 /// will be unified.
1586 /// [upvar inference]: src/librustc_typeck/check/upvar.rs
1587 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1589 TyInt(int_ty) => match int_ty {
1590 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1591 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1592 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1593 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1598 TyError => Some(ty::ClosureKind::Fn),
1600 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1605 /// Typed constant value.
1606 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq)]
1607 pub struct Const<'tcx> {
1610 // FIXME(eddyb) Replace this with a miri value.
1611 pub val: ConstVal<'tcx>,
1614 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}