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 ty::subst::{Substs, Subst};
18 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
23 use std::cmp::Ordering;
25 use syntax::ast::{self, Name};
26 use syntax::symbol::keywords;
33 use self::TypeVariants::*;
35 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
36 pub struct TypeAndMut<'tcx> {
38 pub mutbl: hir::Mutability,
41 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
42 RustcEncodable, RustcDecodable, Copy)]
43 /// A "free" region `fr` can be interpreted as "some region
44 /// at least as big as the scope `fr.scope`".
45 pub struct FreeRegion {
47 pub bound_region: BoundRegion,
50 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
51 RustcEncodable, RustcDecodable, Copy)]
52 pub enum BoundRegion {
53 /// An anonymous region parameter for a given fn (&T)
56 /// Named region parameters for functions (a in &'a T)
58 /// The def-id is needed to distinguish free regions in
59 /// the event of shadowing.
62 /// Fresh bound identifiers created during GLB computations.
65 /// Anonymous region for the implicit env pointer parameter
71 pub fn is_named(&self) -> bool {
73 BoundRegion::BrNamed(..) => true,
79 /// NB: If you change this, you'll probably want to change the corresponding
80 /// AST structure in libsyntax/ast.rs as well.
81 #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
82 pub enum TypeVariants<'tcx> {
83 /// The primitive boolean type. Written as `bool`.
86 /// The primitive character type; holds a Unicode scalar value
87 /// (a non-surrogate code point). Written as `char`.
90 /// A primitive signed integer type. For example, `i32`.
93 /// A primitive unsigned integer type. For example, `u32`.
96 /// A primitive floating-point type. For example, `f64`.
97 TyFloat(ast::FloatTy),
99 /// Structures, enumerations and unions.
101 /// Substs here, possibly against intuition, *may* contain `TyParam`s.
102 /// That is, even after substitution it is possible that there are type
103 /// variables. This happens when the `TyAdt` corresponds to an ADT
104 /// definition and not a concrete use of it.
105 TyAdt(&'tcx AdtDef, &'tcx Substs<'tcx>),
107 /// The pointee of a string slice. Written as `str`.
110 /// An array with the given length. Written as `[T; n]`.
111 TyArray(Ty<'tcx>, &'tcx ty::Const<'tcx>),
113 /// The pointee of an array slice. Written as `[T]`.
116 /// A raw pointer. Written as `*mut T` or `*const T`
117 TyRawPtr(TypeAndMut<'tcx>),
119 /// A reference; a pointer with an associated lifetime. Written as
120 /// `&'a mut T` or `&'a T`.
121 TyRef(Region<'tcx>, TypeAndMut<'tcx>),
123 /// The anonymous type of a function declaration/definition. Each
124 /// function has a unique type.
125 TyFnDef(DefId, &'tcx Substs<'tcx>),
127 /// A pointer to a function. Written as `fn() -> i32`.
128 TyFnPtr(PolyFnSig<'tcx>),
130 /// A trait, defined with `trait`.
131 TyDynamic(Binder<&'tcx Slice<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
133 /// The anonymous type of a closure. Used to represent the type of
135 TyClosure(DefId, ClosureSubsts<'tcx>),
137 /// The anonymous type of a generator. Used to represent the type of
139 TyGenerator(DefId, ClosureSubsts<'tcx>, GeneratorInterior<'tcx>),
141 /// The never type `!`
144 /// A tuple type. For example, `(i32, bool)`.
145 /// The bool indicates whether this is a unit tuple and was created by
146 /// defaulting a diverging type variable with feature(never_type) disabled.
147 /// It's only purpose is for raising future-compatibility warnings for when
148 /// diverging type variables start defaulting to ! instead of ().
149 TyTuple(&'tcx Slice<Ty<'tcx>>, bool),
151 /// The projection of an associated type. For example,
152 /// `<T as Trait<..>>::N`.
153 TyProjection(ProjectionTy<'tcx>),
155 /// Anonymized (`impl Trait`) type found in a return type.
156 /// The DefId comes from the `impl Trait` ast::Ty node, and the
157 /// substitutions are for the generics of the function in question.
158 /// After typeck, the concrete type can be found in the `types` map.
159 TyAnon(DefId, &'tcx Substs<'tcx>),
161 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
164 /// A type variable used during type-checking.
167 /// A placeholder for a type which could not be computed; this is
168 /// propagated to avoid useless error messages.
172 /// A closure can be modeled as a struct that looks like:
174 /// struct Closure<'l0...'li, T0...Tj, U0...Uk> {
180 /// where 'l0...'li and T0...Tj are the lifetime and type parameters
181 /// in scope on the function that defined the closure, and U0...Uk are
182 /// type parameters representing the types of its upvars (borrowed, if
185 /// So, for example, given this function:
187 /// fn foo<'a, T>(data: &'a mut T) {
188 /// do(|| data.count += 1)
191 /// the type of the closure would be something like:
193 /// struct Closure<'a, T, U0> {
197 /// Note that the type of the upvar is not specified in the struct.
198 /// You may wonder how the impl would then be able to use the upvar,
199 /// if it doesn't know it's type? The answer is that the impl is
200 /// (conceptually) not fully generic over Closure but rather tied to
201 /// instances with the expected upvar types:
203 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
207 /// You can see that the *impl* fully specified the type of the upvar
208 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
209 /// (Here, I am assuming that `data` is mut-borrowed.)
211 /// Now, the last question you may ask is: Why include the upvar types
212 /// as extra type parameters? The reason for this design is that the
213 /// upvar types can reference lifetimes that are internal to the
214 /// creating function. In my example above, for example, the lifetime
215 /// `'b` represents the scope of the closure itself; this is some
216 /// subset of `foo`, probably just the scope of the call to the to
217 /// `do()`. If we just had the lifetime/type parameters from the
218 /// enclosing function, we couldn't name this lifetime `'b`. Note that
219 /// there can also be lifetimes in the types of the upvars themselves,
220 /// if one of them happens to be a reference to something that the
221 /// creating fn owns.
223 /// OK, you say, so why not create a more minimal set of parameters
224 /// that just includes the extra lifetime parameters? The answer is
225 /// primarily that it would be hard --- we don't know at the time when
226 /// we create the closure type what the full types of the upvars are,
227 /// nor do we know which are borrowed and which are not. In this
228 /// design, we can just supply a fresh type parameter and figure that
231 /// All right, you say, but why include the type parameters from the
232 /// original function then? The answer is that trans may need them
233 /// when monomorphizing, and they may not appear in the upvars. A
234 /// closure could capture no variables but still make use of some
235 /// in-scope type parameter with a bound (e.g., if our example above
236 /// had an extra `U: Default`, and the closure called `U::default()`).
238 /// There is another reason. This design (implicitly) prohibits
239 /// closures from capturing themselves (except via a trait
240 /// object). This simplifies closure inference considerably, since it
241 /// means that when we infer the kind of a closure or its upvars, we
242 /// don't have to handle cycles where the decisions we make for
243 /// closure C wind up influencing the decisions we ought to make for
244 /// closure C (which would then require fixed point iteration to
245 /// handle). Plus it fixes an ICE. :P
246 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
247 pub struct ClosureSubsts<'tcx> {
248 /// Lifetime and type parameters from the enclosing function,
249 /// concatenated with the types of the upvars.
251 /// These are separated out because trans wants to pass them around
252 /// when monomorphizing.
253 pub substs: &'tcx Substs<'tcx>,
256 impl<'a, 'gcx, 'acx, 'tcx> ClosureSubsts<'tcx> {
258 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'acx>) ->
259 impl Iterator<Item=Ty<'tcx>> + 'tcx
261 let generics = tcx.generics_of(def_id);
262 self.substs[self.substs.len()-generics.own_count()..].iter().map(
263 |t| t.as_type().expect("unexpected region in upvars"))
267 impl<'a, 'gcx, 'tcx> ClosureSubsts<'tcx> {
268 /// This returns the types of the MIR locals which had to be stored across suspension points.
269 /// It is calculated in rustc_mir::transform::generator::StateTransform.
270 /// All the types here must be in the tuple in GeneratorInterior.
271 pub fn state_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
272 impl Iterator<Item=Ty<'tcx>> + 'a
274 let state = tcx.generator_layout(def_id).fields.iter();
275 state.map(move |d| d.ty.subst(tcx, self.substs))
278 /// This is the types of all the fields stored in a generator.
279 /// It includes the upvars, state types and the state discriminant which is u32.
280 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
281 impl Iterator<Item=Ty<'tcx>> + 'a
283 let upvars = self.upvar_tys(def_id, tcx);
284 let state = self.state_tys(def_id, tcx);
285 upvars.chain(iter::once(tcx.types.u32)).chain(state)
289 /// This describes the types that can be contained in a generator.
290 /// It will be a type variable initially and unified in the last stages of typeck of a body.
291 /// It contains a tuple of all the types that could end up on a generator frame.
292 /// The state transformation MIR pass may only produce layouts which mention types in this tuple.
293 /// Upvars are not counted here.
294 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
295 pub struct GeneratorInterior<'tcx> {
296 pub witness: Ty<'tcx>,
299 impl<'tcx> GeneratorInterior<'tcx> {
300 pub fn new(witness: Ty<'tcx>) -> GeneratorInterior<'tcx> {
301 GeneratorInterior { witness }
304 pub fn as_slice(&self) -> &'tcx Slice<Ty<'tcx>> {
305 match self.witness.sty {
306 ty::TyTuple(s, _) => s,
312 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
313 pub enum ExistentialPredicate<'tcx> {
315 Trait(ExistentialTraitRef<'tcx>),
316 /// e.g. Iterator::Item = T
317 Projection(ExistentialProjection<'tcx>),
322 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
323 pub fn cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
324 use self::ExistentialPredicate::*;
325 match (*self, *other) {
326 (Trait(_), Trait(_)) => Ordering::Equal,
327 (Projection(ref a), Projection(ref b)) =>
328 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
329 (AutoTrait(ref a), AutoTrait(ref b)) =>
330 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
331 (Trait(_), _) => Ordering::Less,
332 (Projection(_), Trait(_)) => Ordering::Greater,
333 (Projection(_), _) => Ordering::Less,
334 (AutoTrait(_), _) => Ordering::Greater,
340 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
341 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
342 -> ty::Predicate<'tcx> {
344 match *self.skip_binder() {
345 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
346 ExistentialPredicate::Projection(p) =>
347 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
348 ExistentialPredicate::AutoTrait(did) => {
349 let trait_ref = Binder(ty::TraitRef {
351 substs: tcx.mk_substs_trait(self_ty, &[]),
353 trait_ref.to_predicate()
359 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice<ExistentialPredicate<'tcx>> {}
361 impl<'tcx> Slice<ExistentialPredicate<'tcx>> {
362 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
364 Some(&ExistentialPredicate::Trait(tr)) => Some(tr),
370 pub fn projection_bounds<'a>(&'a self) ->
371 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
372 self.iter().filter_map(|predicate| {
374 ExistentialPredicate::Projection(p) => Some(p),
381 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
382 self.iter().filter_map(|predicate| {
384 ExistentialPredicate::AutoTrait(d) => Some(d),
391 impl<'tcx> Binder<&'tcx Slice<ExistentialPredicate<'tcx>>> {
392 pub fn principal(&self) -> Option<PolyExistentialTraitRef<'tcx>> {
393 self.skip_binder().principal().map(Binder)
397 pub fn projection_bounds<'a>(&'a self) ->
398 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
399 self.skip_binder().projection_bounds().map(Binder)
403 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
404 self.skip_binder().auto_traits()
407 pub fn iter<'a>(&'a self)
408 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
409 self.skip_binder().iter().cloned().map(Binder)
413 /// A complete reference to a trait. These take numerous guises in syntax,
414 /// but perhaps the most recognizable form is in a where clause:
418 /// This would be represented by a trait-reference where the def-id is the
419 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
420 /// and `U` as parameter 1.
422 /// Trait references also appear in object types like `Foo<U>`, but in
423 /// that case the `Self` parameter is absent from the substitutions.
425 /// Note that a `TraitRef` introduces a level of region binding, to
426 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
427 /// U>` or higher-ranked object types.
428 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
429 pub struct TraitRef<'tcx> {
431 pub substs: &'tcx Substs<'tcx>,
434 impl<'tcx> TraitRef<'tcx> {
435 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
436 TraitRef { def_id: def_id, substs: substs }
439 pub fn self_ty(&self) -> Ty<'tcx> {
440 self.substs.type_at(0)
443 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
444 // Select only the "input types" from a trait-reference. For
445 // now this is all the types that appear in the
446 // trait-reference, but it should eventually exclude
452 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
454 impl<'tcx> PolyTraitRef<'tcx> {
455 pub fn self_ty(&self) -> Ty<'tcx> {
459 pub fn def_id(&self) -> DefId {
463 pub fn substs(&self) -> &'tcx Substs<'tcx> {
464 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
468 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
469 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
473 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
474 // Note that we preserve binding levels
475 Binder(ty::TraitPredicate { trait_ref: self.0.clone() })
479 /// An existential reference to a trait, where `Self` is erased.
480 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
482 /// exists T. T: Trait<'a, 'b, X, Y>
484 /// The substitutions don't include the erased `Self`, only trait
485 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
486 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
487 pub struct ExistentialTraitRef<'tcx> {
489 pub substs: &'tcx Substs<'tcx>,
492 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
493 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
494 // Select only the "input types" from a trait-reference. For
495 // now this is all the types that appear in the
496 // trait-reference, but it should eventually exclude
501 /// Object types don't have a self-type specified. Therefore, when
502 /// we convert the principal trait-ref into a normal trait-ref,
503 /// you must give *some* self-type. A common choice is `mk_err()`
504 /// or some skolemized type.
505 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
506 -> ty::TraitRef<'tcx> {
507 // otherwise the escaping regions would be captured by the binder
508 assert!(!self_ty.has_escaping_regions());
512 substs: tcx.mk_substs(
513 iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned()))
518 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
520 impl<'tcx> PolyExistentialTraitRef<'tcx> {
521 pub fn def_id(&self) -> DefId {
525 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
526 // FIXME(#20664) every use of this fn is probably a bug, it should yield Binder<>
531 /// Binder is a binder for higher-ranked lifetimes. It is part of the
532 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
533 /// (which would be represented by the type `PolyTraitRef ==
534 /// Binder<TraitRef>`). Note that when we skolemize, instantiate,
535 /// erase, or otherwise "discharge" these bound regions, we change the
536 /// type from `Binder<T>` to just `T` (see
537 /// e.g. `liberate_late_bound_regions`).
538 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
539 pub struct Binder<T>(pub T);
542 /// Skips the binder and returns the "bound" value. This is a
543 /// risky thing to do because it's easy to get confused about
544 /// debruijn indices and the like. It is usually better to
545 /// discharge the binder using `no_late_bound_regions` or
546 /// `replace_late_bound_regions` or something like
547 /// that. `skip_binder` is only valid when you are either
548 /// extracting data that has nothing to do with bound regions, you
549 /// are doing some sort of test that does not involve bound
550 /// regions, or you are being very careful about your depth
553 /// Some examples where `skip_binder` is reasonable:
554 /// - extracting the def-id from a PolyTraitRef;
555 /// - comparing the self type of a PolyTraitRef to see if it is equal to
556 /// a type parameter `X`, since the type `X` does not reference any regions
557 pub fn skip_binder(&self) -> &T {
561 pub fn as_ref(&self) -> Binder<&T> {
565 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
566 where F: FnOnce(&T) -> U
568 self.as_ref().map_bound(f)
571 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
572 where F: FnOnce(T) -> U
574 ty::Binder(f(self.0))
578 /// Represents the projection of an associated type. In explicit UFCS
579 /// form this would be written `<T as Trait<..>>::N`.
580 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
581 pub struct ProjectionTy<'tcx> {
582 /// The parameters of the associated item.
583 pub substs: &'tcx Substs<'tcx>,
585 /// The DefId of the TraitItem for the associated type N.
587 /// Note that this is not the DefId of the TraitRef containing this
588 /// associated type, which is in tcx.associated_item(item_def_id).container.
589 pub item_def_id: DefId,
592 impl<'a, 'tcx> ProjectionTy<'tcx> {
593 /// Construct a ProjectionTy by searching the trait from trait_ref for the
594 /// associated item named item_name.
595 pub fn from_ref_and_name(
596 tcx: TyCtxt, trait_ref: ty::TraitRef<'tcx>, item_name: Name
597 ) -> ProjectionTy<'tcx> {
598 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
599 item.kind == ty::AssociatedKind::Type &&
600 tcx.hygienic_eq(item_name, item.name, trait_ref.def_id)
604 substs: trait_ref.substs,
609 /// Extracts the underlying trait reference from this projection.
610 /// For example, if this is a projection of `<T as Iterator>::Item`,
611 /// then this function would return a `T: Iterator` trait reference.
612 pub fn trait_ref(&self, tcx: TyCtxt) -> ty::TraitRef<'tcx> {
613 let def_id = tcx.associated_item(self.item_def_id).container.id();
620 pub fn self_ty(&self) -> Ty<'tcx> {
621 self.substs.type_at(0)
625 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
626 pub struct GenSig<'tcx> {
627 pub yield_ty: Ty<'tcx>,
628 pub return_ty: Ty<'tcx>,
631 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
633 impl<'tcx> PolyGenSig<'tcx> {
634 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
635 self.map_bound_ref(|sig| sig.yield_ty)
637 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
638 self.map_bound_ref(|sig| sig.return_ty)
642 /// Signature of a function type, which I have arbitrarily
643 /// decided to use to refer to the input/output types.
645 /// - `inputs` is the list of arguments and their modes.
646 /// - `output` is the return type.
647 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
648 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
649 pub struct FnSig<'tcx> {
650 pub inputs_and_output: &'tcx Slice<Ty<'tcx>>,
652 pub unsafety: hir::Unsafety,
656 impl<'tcx> FnSig<'tcx> {
657 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
658 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
661 pub fn output(&self) -> Ty<'tcx> {
662 self.inputs_and_output[self.inputs_and_output.len() - 1]
666 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
668 impl<'tcx> PolyFnSig<'tcx> {
669 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
670 Binder(self.skip_binder().inputs())
672 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
673 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
675 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
676 self.map_bound_ref(|fn_sig| fn_sig.output().clone())
678 pub fn variadic(&self) -> bool {
679 self.skip_binder().variadic
681 pub fn unsafety(&self) -> hir::Unsafety {
682 self.skip_binder().unsafety
684 pub fn abi(&self) -> abi::Abi {
685 self.skip_binder().abi
689 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
695 impl<'a, 'gcx, 'tcx> ParamTy {
696 pub fn new(index: u32, name: Name) -> ParamTy {
697 ParamTy { idx: index, name: name }
700 pub fn for_self() -> ParamTy {
701 ParamTy::new(0, keywords::SelfType.name())
704 pub fn for_def(def: &ty::TypeParameterDef) -> ParamTy {
705 ParamTy::new(def.index, def.name)
708 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
709 tcx.mk_param(self.idx, self.name)
712 pub fn is_self(&self) -> bool {
713 if self.name == keywords::SelfType.name() {
714 assert_eq!(self.idx, 0);
722 /// A [De Bruijn index][dbi] is a standard means of representing
723 /// regions (and perhaps later types) in a higher-ranked setting. In
724 /// particular, imagine a type like this:
726 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
729 /// | +------------+ 1 | |
731 /// +--------------------------------+ 2 |
733 /// +------------------------------------------+ 1
735 /// In this type, there are two binders (the outer fn and the inner
736 /// fn). We need to be able to determine, for any given region, which
737 /// fn type it is bound by, the inner or the outer one. There are
738 /// various ways you can do this, but a De Bruijn index is one of the
739 /// more convenient and has some nice properties. The basic idea is to
740 /// count the number of binders, inside out. Some examples should help
741 /// clarify what I mean.
743 /// Let's start with the reference type `&'b isize` that is the first
744 /// argument to the inner function. This region `'b` is assigned a De
745 /// Bruijn index of 1, meaning "the innermost binder" (in this case, a
746 /// fn). The region `'a` that appears in the second argument type (`&'a
747 /// isize`) would then be assigned a De Bruijn index of 2, meaning "the
748 /// second-innermost binder". (These indices are written on the arrays
751 /// What is interesting is that De Bruijn index attached to a particular
752 /// variable will vary depending on where it appears. For example,
753 /// the final type `&'a char` also refers to the region `'a` declared on
754 /// the outermost fn. But this time, this reference is not nested within
755 /// any other binders (i.e., it is not an argument to the inner fn, but
756 /// rather the outer one). Therefore, in this case, it is assigned a
757 /// De Bruijn index of 1, because the innermost binder in that location
760 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
761 #[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, Copy)]
762 pub struct DebruijnIndex {
763 /// We maintain the invariant that this is never 0. So 1 indicates
764 /// the innermost binder. To ensure this, create with `DebruijnIndex::new`.
768 pub type Region<'tcx> = &'tcx RegionKind;
770 /// Representation of regions.
772 /// Unlike types, most region variants are "fictitious", not concrete,
773 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
774 /// ones representing concrete regions.
778 /// These are regions that are stored behind a binder and must be substituted
779 /// with some concrete region before being used. There are 2 kind of
780 /// bound regions: early-bound, which are bound in an item's Generics,
781 /// and are substituted by a Substs, and late-bound, which are part of
782 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
783 /// the likes of `liberate_late_bound_regions`. The distinction exists
784 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
786 /// Unlike TyParam-s, bound regions are not supposed to exist "in the wild"
787 /// outside their binder, e.g. in types passed to type inference, and
788 /// should first be substituted (by skolemized regions, free regions,
789 /// or region variables).
791 /// ## Skolemized and Free Regions
793 /// One often wants to work with bound regions without knowing their precise
794 /// identity. For example, when checking a function, the lifetime of a borrow
795 /// can end up being assigned to some region parameter. In these cases,
796 /// it must be ensured that bounds on the region can't be accidentally
797 /// assumed without being checked.
799 /// The process of doing that is called "skolemization". The bound regions
800 /// are replaced by skolemized markers, which don't satisfy any relation
801 /// not explicitly provided.
803 /// There are 2 kinds of skolemized regions in rustc: `ReFree` and
804 /// `ReSkolemized`. When checking an item's body, `ReFree` is supposed
805 /// to be used. These also support explicit bounds: both the internally-stored
806 /// *scope*, which the region is assumed to outlive, as well as other
807 /// relations stored in the `FreeRegionMap`. Note that these relations
808 /// aren't checked when you `make_subregion` (or `eq_types`), only by
809 /// `resolve_regions_and_report_errors`.
811 /// When working with higher-ranked types, some region relations aren't
812 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
813 /// `ReSkolemized` is designed for this purpose. In these contexts,
814 /// there's also the risk that some inference variable laying around will
815 /// get unified with your skolemized region: if you want to check whether
816 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
817 /// with a skolemized region `'%a`, the variable `'_` would just be
818 /// instantiated to the skolemized region `'%a`, which is wrong because
819 /// the inference variable is supposed to satisfy the relation
820 /// *for every value of the skolemized region*. To ensure that doesn't
821 /// happen, you can use `leak_check`. This is more clearly explained
822 /// by infer/higher_ranked/README.md.
824 /// [1] http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
825 /// [2] http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
826 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable)]
827 pub enum RegionKind {
828 // Region bound in a type or fn declaration which will be
829 // substituted 'early' -- that is, at the same time when type
830 // parameters are substituted.
831 ReEarlyBound(EarlyBoundRegion),
833 // Region bound in a function scope, which will be substituted when the
834 // function is called.
835 ReLateBound(DebruijnIndex, BoundRegion),
837 /// When checking a function body, the types of all arguments and so forth
838 /// that refer to bound region parameters are modified to refer to free
839 /// region parameters.
842 /// A concrete region naming some statically determined scope
843 /// (e.g. an expression or sequence of statements) within the
844 /// current function.
845 ReScope(region::Scope),
847 /// Static data that has an "infinite" lifetime. Top in the region lattice.
850 /// A region variable. Should not exist after typeck.
853 /// A skolemized region - basically the higher-ranked version of ReFree.
854 /// Should not exist after typeck.
855 ReSkolemized(SkolemizedRegionVid, BoundRegion),
857 /// Empty lifetime is for data that is never accessed.
858 /// Bottom in the region lattice. We treat ReEmpty somewhat
859 /// specially; at least right now, we do not generate instances of
860 /// it during the GLB computations, but rather
861 /// generate an error instead. This is to improve error messages.
862 /// The only way to get an instance of ReEmpty is to have a region
863 /// variable with no constraints.
866 /// Erased region, used by trait selection, in MIR and during trans.
870 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
872 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug)]
873 pub struct EarlyBoundRegion {
879 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
884 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
889 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
890 pub struct FloatVid {
894 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy)]
895 pub struct RegionVid {
899 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
900 pub struct SkolemizedRegionVid {
904 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
910 /// A `FreshTy` is one that is generated as a replacement for an
911 /// unbound type variable. This is convenient for caching etc. See
912 /// `infer::freshen` for more details.
918 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
919 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
920 pub struct ExistentialProjection<'tcx> {
921 pub item_def_id: DefId,
922 pub substs: &'tcx Substs<'tcx>,
926 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
928 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
929 /// Extracts the underlying existential trait reference from this projection.
930 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
931 /// then this function would return a `exists T. T: Iterator` existential trait
933 pub fn trait_ref(&self, tcx: TyCtxt) -> ty::ExistentialTraitRef<'tcx> {
934 let def_id = tcx.associated_item(self.item_def_id).container.id();
935 ty::ExistentialTraitRef{
941 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
943 -> ty::ProjectionPredicate<'tcx>
945 // otherwise the escaping regions would be captured by the binders
946 assert!(!self_ty.has_escaping_regions());
948 ty::ProjectionPredicate {
949 projection_ty: ty::ProjectionTy {
950 item_def_id: self.item_def_id,
951 substs: tcx.mk_substs(
952 iter::once(Kind::from(self_ty)).chain(self.substs.iter().cloned())),
959 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
960 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
961 -> ty::PolyProjectionPredicate<'tcx> {
962 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
967 pub fn new(depth: u32) -> DebruijnIndex {
969 DebruijnIndex { depth: depth }
972 pub fn shifted(&self, amount: u32) -> DebruijnIndex {
973 DebruijnIndex { depth: self.depth + amount }
979 pub fn is_late_bound(&self) -> bool {
981 ty::ReLateBound(..) => true,
986 pub fn needs_infer(&self) -> bool {
988 ty::ReVar(..) | ty::ReSkolemized(..) => true,
993 pub fn escapes_depth(&self, depth: u32) -> bool {
995 ty::ReLateBound(debruijn, _) => debruijn.depth > depth,
1000 /// Returns the depth of `self` from the (1-based) binding level `depth`
1001 pub fn from_depth(&self, depth: u32) -> RegionKind {
1003 ty::ReLateBound(debruijn, r) => ty::ReLateBound(DebruijnIndex {
1004 depth: debruijn.depth - (depth - 1)
1010 pub fn type_flags(&self) -> TypeFlags {
1011 let mut flags = TypeFlags::empty();
1015 flags = flags | TypeFlags::HAS_RE_INFER;
1016 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1018 ty::ReSkolemized(..) => {
1019 flags = flags | TypeFlags::HAS_RE_INFER;
1020 flags = flags | TypeFlags::HAS_RE_SKOL;
1021 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1023 ty::ReLateBound(..) => { }
1024 ty::ReEarlyBound(..) => { flags = flags | TypeFlags::HAS_RE_EARLY_BOUND; }
1025 ty::ReStatic | ty::ReErased => { }
1026 _ => { flags = flags | TypeFlags::HAS_FREE_REGIONS; }
1030 ty::ReStatic | ty::ReEmpty | ty::ReErased => (),
1031 _ => flags = flags | TypeFlags::HAS_LOCAL_NAMES,
1034 debug!("type_flags({:?}) = {:?}", self, flags);
1041 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1042 pub fn as_opt_param_ty(&self) -> Option<ty::ParamTy> {
1044 ty::TyParam(ref d) => Some(d.clone()),
1049 pub fn is_nil(&self) -> bool {
1051 TyTuple(ref tys, _) => tys.is_empty(),
1056 pub fn is_never(&self) -> bool {
1063 /// Test whether this is a `()` which was produced by defaulting a
1064 /// diverging type variable with feature(never_type) disabled.
1065 pub fn is_defaulted_unit(&self) -> bool {
1067 TyTuple(_, true) => true,
1072 pub fn is_primitive(&self) -> bool {
1074 TyBool | TyChar | TyInt(_) | TyUint(_) | TyFloat(_) => true,
1079 pub fn is_ty_var(&self) -> bool {
1081 TyInfer(TyVar(_)) => true,
1086 pub fn is_phantom_data(&self) -> bool {
1087 if let TyAdt(def, _) = self.sty {
1088 def.is_phantom_data()
1094 pub fn is_bool(&self) -> bool { self.sty == TyBool }
1096 pub fn is_param(&self, index: u32) -> bool {
1098 ty::TyParam(ref data) => data.idx == index,
1103 pub fn is_self(&self) -> bool {
1105 TyParam(ref p) => p.is_self(),
1110 pub fn is_slice(&self) -> bool {
1112 TyRawPtr(mt) | TyRef(_, mt) => match mt.ty.sty {
1113 TySlice(_) | TyStr => true,
1120 pub fn is_structural(&self) -> bool {
1122 TyAdt(..) | TyTuple(..) | TyArray(..) | TyClosure(..) => true,
1123 _ => self.is_slice() | self.is_trait(),
1128 pub fn is_simd(&self) -> bool {
1130 TyAdt(def, _) => def.repr.simd(),
1135 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1137 TyArray(ty, _) | TySlice(ty) => ty,
1138 TyStr => tcx.mk_mach_uint(ast::UintTy::U8),
1139 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1143 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1145 TyAdt(def, substs) => {
1146 def.struct_variant().fields[0].ty(tcx, substs)
1148 _ => bug!("simd_type called on invalid type")
1152 pub fn simd_size(&self, _cx: TyCtxt) -> usize {
1154 TyAdt(def, _) => def.struct_variant().fields.len(),
1155 _ => bug!("simd_size called on invalid type")
1159 pub fn is_region_ptr(&self) -> bool {
1166 pub fn is_mutable_pointer(&self) -> bool {
1168 TyRawPtr(tnm) | TyRef(_, tnm) => if let hir::Mutability::MutMutable = tnm.mutbl {
1177 pub fn is_unsafe_ptr(&self) -> bool {
1179 TyRawPtr(_) => return true,
1184 pub fn is_box(&self) -> bool {
1186 TyAdt(def, _) => def.is_box(),
1191 /// panics if called on any type other than `Box<T>`
1192 pub fn boxed_ty(&self) -> Ty<'tcx> {
1194 TyAdt(def, substs) if def.is_box() => substs.type_at(0),
1195 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1199 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1200 /// (A TyRawPtr is scalar because it represents a non-managed pointer, so its
1201 /// contents are abstract to rustc.)
1202 pub fn is_scalar(&self) -> bool {
1204 TyBool | TyChar | TyInt(_) | TyFloat(_) | TyUint(_) |
1205 TyInfer(IntVar(_)) | TyInfer(FloatVar(_)) |
1206 TyFnDef(..) | TyFnPtr(_) | TyRawPtr(_) => true,
1211 /// Returns true if this type is a floating point type and false otherwise.
1212 pub fn is_floating_point(&self) -> bool {
1215 TyInfer(FloatVar(_)) => true,
1220 pub fn is_trait(&self) -> bool {
1222 TyDynamic(..) => true,
1227 pub fn is_closure(&self) -> bool {
1229 TyClosure(..) => true,
1234 pub fn is_integral(&self) -> bool {
1236 TyInfer(IntVar(_)) | TyInt(_) | TyUint(_) => true,
1241 pub fn is_fresh(&self) -> bool {
1243 TyInfer(FreshTy(_)) => true,
1244 TyInfer(FreshIntTy(_)) => true,
1245 TyInfer(FreshFloatTy(_)) => true,
1250 pub fn is_uint(&self) -> bool {
1252 TyInfer(IntVar(_)) | TyUint(ast::UintTy::Us) => true,
1257 pub fn is_char(&self) -> bool {
1264 pub fn is_fp(&self) -> bool {
1266 TyInfer(FloatVar(_)) | TyFloat(_) => true,
1271 pub fn is_numeric(&self) -> bool {
1272 self.is_integral() || self.is_fp()
1275 pub fn is_signed(&self) -> bool {
1282 pub fn is_machine(&self) -> bool {
1284 TyInt(ast::IntTy::Is) | TyUint(ast::UintTy::Us) => false,
1285 TyInt(..) | TyUint(..) | TyFloat(..) => true,
1290 pub fn has_concrete_skeleton(&self) -> bool {
1292 TyParam(_) | TyInfer(_) | TyError => false,
1297 /// Returns the type and mutability of *ty.
1299 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1300 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1301 pub fn builtin_deref(&self, explicit: bool, pref: ty::LvaluePreference)
1302 -> Option<TypeAndMut<'tcx>>
1305 TyAdt(def, _) if def.is_box() => {
1307 ty: self.boxed_ty(),
1308 mutbl: if pref == ty::PreferMutLvalue {
1315 TyRef(_, mt) => Some(mt),
1316 TyRawPtr(mt) if explicit => Some(mt),
1321 /// Returns the type of ty[i]
1322 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1324 TyArray(ty, _) | TySlice(ty) => Some(ty),
1329 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1331 TyFnDef(def_id, substs) => {
1332 tcx.fn_sig(def_id).subst(tcx, substs)
1335 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1339 pub fn is_fn(&self) -> bool {
1341 TyFnDef(..) | TyFnPtr(_) => true,
1346 pub fn ty_to_def_id(&self) -> Option<DefId> {
1348 TyDynamic(ref tt, ..) => tt.principal().map(|p| p.def_id()),
1349 TyAdt(def, _) => Some(def.did),
1350 TyClosure(id, _) => Some(id),
1355 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1357 TyAdt(adt, _) => Some(adt),
1362 /// Returns the regions directly referenced from this type (but
1363 /// not types reachable from this type via `walk_tys`). This
1364 /// ignores late-bound regions binders.
1365 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1367 TyRef(region, _) => {
1370 TyDynamic(ref obj, region) => {
1371 let mut v = vec![region];
1372 if let Some(p) = obj.principal() {
1373 v.extend(p.skip_binder().substs.regions());
1377 TyAdt(_, substs) | TyAnon(_, substs) => {
1378 substs.regions().collect()
1380 TyClosure(_, ref substs) | TyGenerator(_, ref substs, _) => {
1381 substs.substs.regions().collect()
1383 TyProjection(ref data) => {
1384 data.substs.regions().collect()
1408 /// Typed constant value.
1409 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq)]
1410 pub struct Const<'tcx> {
1413 // FIXME(eddyb) Replace this with a miri value.
1414 pub val: ConstVal<'tcx>,
1417 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}