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 TyKind and its major components
13 use hir::def_id::DefId;
15 use mir::interpret::ConstValue;
17 use polonius_engine::Atom;
18 use rustc_data_structures::indexed_vec::Idx;
19 use ty::subst::{Substs, Subst, Kind, UnpackedKind};
20 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
21 use ty::{List, TyS, ParamEnvAnd, ParamEnv};
22 use util::captures::Captures;
23 use mir::interpret::{Scalar, Pointer};
26 use std::cmp::Ordering;
27 use rustc_target::spec::abi;
28 use syntax::ast::{self, Ident};
29 use syntax::symbol::{keywords, InternedString};
38 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
39 pub struct TypeAndMut<'tcx> {
41 pub mutbl: hir::Mutability,
44 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
45 RustcEncodable, RustcDecodable, Copy)]
46 /// A "free" region `fr` can be interpreted as "some region
47 /// at least as big as the scope `fr.scope`".
48 pub struct FreeRegion {
50 pub bound_region: BoundRegion,
53 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
54 RustcEncodable, RustcDecodable, Copy)]
55 pub enum BoundRegion {
56 /// An anonymous region parameter for a given fn (&T)
59 /// Named region parameters for functions (a in &'a T)
61 /// The def-id is needed to distinguish free regions in
62 /// the event of shadowing.
63 BrNamed(DefId, InternedString),
65 /// Fresh bound identifiers created during GLB computations.
68 /// Anonymous region for the implicit env pointer parameter
74 pub fn is_named(&self) -> bool {
76 BoundRegion::BrNamed(..) => true,
82 /// N.B., If you change this, you'll probably want to change the corresponding
83 /// AST structure in `libsyntax/ast.rs` as well.
84 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
85 pub enum TyKind<'tcx> {
86 /// The primitive boolean type. Written as `bool`.
89 /// The primitive character type; holds a Unicode scalar value
90 /// (a non-surrogate code point). Written as `char`.
93 /// A primitive signed integer type. For example, `i32`.
96 /// A primitive unsigned integer type. For example, `u32`.
99 /// A primitive floating-point type. For example, `f64`.
102 /// Structures, enumerations and unions.
104 /// Substs here, possibly against intuition, *may* contain `Param`s.
105 /// That is, even after substitution it is possible that there are type
106 /// variables. This happens when the `Adt` corresponds to an ADT
107 /// definition and not a concrete use of it.
108 Adt(&'tcx AdtDef, &'tcx Substs<'tcx>),
112 /// The pointee of a string slice. Written as `str`.
115 /// An array with the given length. Written as `[T; n]`.
116 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
118 /// The pointee of an array slice. Written as `[T]`.
121 /// A raw pointer. Written as `*mut T` or `*const T`
122 RawPtr(TypeAndMut<'tcx>),
124 /// A reference; a pointer with an associated lifetime. Written as
125 /// `&'a mut T` or `&'a T`.
126 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
128 /// The anonymous type of a function declaration/definition. Each
129 /// function has a unique type.
130 FnDef(DefId, &'tcx Substs<'tcx>),
132 /// A pointer to a function. Written as `fn() -> i32`.
133 FnPtr(PolyFnSig<'tcx>),
135 /// A trait, defined with `trait`.
136 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
138 /// The anonymous type of a closure. Used to represent the type of
140 Closure(DefId, ClosureSubsts<'tcx>),
142 /// The anonymous type of a generator. Used to represent the type of
144 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
146 /// A type representin the types stored inside a generator.
147 /// This should only appear in GeneratorInteriors.
148 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
150 /// The never type `!`
153 /// A tuple type. For example, `(i32, bool)`.
154 Tuple(&'tcx List<Ty<'tcx>>),
156 /// The projection of an associated type. For example,
157 /// `<T as Trait<..>>::N`.
158 Projection(ProjectionTy<'tcx>),
160 /// A placeholder type used when we do not have enough information
161 /// to normalize the projection of an associated type to an
162 /// existing concrete type. Currently only used with chalk-engine.
163 UnnormalizedProjection(ProjectionTy<'tcx>),
165 /// Opaque (`impl Trait`) type found in a return type.
166 /// The `DefId` comes either from
167 /// * the `impl Trait` ast::Ty node,
168 /// * or the `existential type` declaration
169 /// The substitutions are for the generics of the function in question.
170 /// After typeck, the concrete type can be found in the `types` map.
171 Opaque(DefId, &'tcx Substs<'tcx>),
173 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
176 /// A type variable used during type checking.
179 /// A placeholder for a type which could not be computed; this is
180 /// propagated to avoid useless error messages.
184 /// A closure can be modeled as a struct that looks like:
186 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
194 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
195 /// in scope on the function that defined the closure,
196 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
197 /// is rather hackily encoded via a scalar type. See
198 /// `TyS::to_opt_closure_kind` for details.
199 /// - CS represents the *closure signature*, representing as a `fn()`
200 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
201 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
203 /// - U0...Uk are type parameters representing the types of its upvars
204 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
205 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
207 /// So, for example, given this function:
209 /// fn foo<'a, T>(data: &'a mut T) {
210 /// do(|| data.count += 1)
213 /// the type of the closure would be something like:
215 /// struct Closure<'a, T, U0> {
219 /// Note that the type of the upvar is not specified in the struct.
220 /// You may wonder how the impl would then be able to use the upvar,
221 /// if it doesn't know it's type? The answer is that the impl is
222 /// (conceptually) not fully generic over Closure but rather tied to
223 /// instances with the expected upvar types:
225 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
229 /// You can see that the *impl* fully specified the type of the upvar
230 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
231 /// (Here, I am assuming that `data` is mut-borrowed.)
233 /// Now, the last question you may ask is: Why include the upvar types
234 /// as extra type parameters? The reason for this design is that the
235 /// upvar types can reference lifetimes that are internal to the
236 /// creating function. In my example above, for example, the lifetime
237 /// `'b` represents the scope of the closure itself; this is some
238 /// subset of `foo`, probably just the scope of the call to the to
239 /// `do()`. If we just had the lifetime/type parameters from the
240 /// enclosing function, we couldn't name this lifetime `'b`. Note that
241 /// there can also be lifetimes in the types of the upvars themselves,
242 /// if one of them happens to be a reference to something that the
243 /// creating fn owns.
245 /// OK, you say, so why not create a more minimal set of parameters
246 /// that just includes the extra lifetime parameters? The answer is
247 /// primarily that it would be hard --- we don't know at the time when
248 /// we create the closure type what the full types of the upvars are,
249 /// nor do we know which are borrowed and which are not. In this
250 /// design, we can just supply a fresh type parameter and figure that
253 /// All right, you say, but why include the type parameters from the
254 /// original function then? The answer is that codegen may need them
255 /// when monomorphizing, and they may not appear in the upvars. A
256 /// closure could capture no variables but still make use of some
257 /// in-scope type parameter with a bound (e.g., if our example above
258 /// had an extra `U: Default`, and the closure called `U::default()`).
260 /// There is another reason. This design (implicitly) prohibits
261 /// closures from capturing themselves (except via a trait
262 /// object). This simplifies closure inference considerably, since it
263 /// means that when we infer the kind of a closure or its upvars, we
264 /// don't have to handle cycles where the decisions we make for
265 /// closure C wind up influencing the decisions we ought to make for
266 /// closure C (which would then require fixed point iteration to
267 /// handle). Plus it fixes an ICE. :P
271 /// Perhaps surprisingly, `ClosureSubsts` are also used for
272 /// generators. In that case, what is written above is only half-true
273 /// -- the set of type parameters is similar, but the role of CK and
274 /// CS are different. CK represents the "yield type" and CS
275 /// represents the "return type" of the generator.
277 /// It'd be nice to split this struct into ClosureSubsts and
278 /// GeneratorSubsts, I believe. -nmatsakis
279 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
280 pub struct ClosureSubsts<'tcx> {
281 /// Lifetime and type parameters from the enclosing function,
282 /// concatenated with the types of the upvars.
284 /// These are separated out because codegen wants to pass them around
285 /// when monomorphizing.
286 pub substs: &'tcx Substs<'tcx>,
289 /// Struct returned by `split()`. Note that these are subslices of the
290 /// parent slice and not canonical substs themselves.
291 struct SplitClosureSubsts<'tcx> {
292 closure_kind_ty: Ty<'tcx>,
293 closure_sig_ty: Ty<'tcx>,
294 upvar_kinds: &'tcx [Kind<'tcx>],
297 impl<'tcx> ClosureSubsts<'tcx> {
298 /// Divides the closure substs into their respective
299 /// components. Single source of truth with respect to the
301 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
302 let generics = tcx.generics_of(def_id);
303 let parent_len = generics.parent_count;
305 closure_kind_ty: self.substs.type_at(parent_len),
306 closure_sig_ty: self.substs.type_at(parent_len + 1),
307 upvar_kinds: &self.substs[parent_len + 2..],
312 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
313 impl Iterator<Item=Ty<'tcx>> + 'tcx
315 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
316 upvar_kinds.iter().map(|t| {
317 if let UnpackedKind::Type(ty) = t.unpack() {
320 bug!("upvar should be type")
325 /// Returns the closure kind for this closure; may return a type
326 /// variable during inference. To get the closure kind during
327 /// inference, use `infcx.closure_kind(def_id, substs)`.
328 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
329 self.split(def_id, tcx).closure_kind_ty
332 /// Returns the type representing the closure signature for this
333 /// closure; may contain type variables during inference. To get
334 /// the closure signature during inference, use
335 /// `infcx.fn_sig(def_id)`.
336 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
337 self.split(def_id, tcx).closure_sig_ty
340 /// Returns the closure kind for this closure; only usable outside
341 /// of an inference context, because in that context we know that
342 /// there are no type variables.
344 /// If you have an inference context, use `infcx.closure_kind()`.
345 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
346 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
349 /// Extracts the signature from the closure; only usable outside
350 /// of an inference context, because in that context we know that
351 /// there are no type variables.
353 /// If you have an inference context, use `infcx.closure_sig()`.
354 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
355 match self.closure_sig_ty(def_id, tcx).sty {
356 ty::FnPtr(sig) => sig,
357 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
362 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
363 pub struct GeneratorSubsts<'tcx> {
364 pub substs: &'tcx Substs<'tcx>,
367 struct SplitGeneratorSubsts<'tcx> {
371 upvar_kinds: &'tcx [Kind<'tcx>],
374 impl<'tcx> GeneratorSubsts<'tcx> {
375 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
376 let generics = tcx.generics_of(def_id);
377 let parent_len = generics.parent_count;
378 SplitGeneratorSubsts {
379 yield_ty: self.substs.type_at(parent_len),
380 return_ty: self.substs.type_at(parent_len + 1),
381 witness: self.substs.type_at(parent_len + 2),
382 upvar_kinds: &self.substs[parent_len + 3..],
386 /// This describes the types that can be contained in a generator.
387 /// It will be a type variable initially and unified in the last stages of typeck of a body.
388 /// It contains a tuple of all the types that could end up on a generator frame.
389 /// The state transformation MIR pass may only produce layouts which mention types
390 /// in this tuple. Upvars are not counted here.
391 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
392 self.split(def_id, tcx).witness
396 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
397 impl Iterator<Item=Ty<'tcx>> + 'tcx
399 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
400 upvar_kinds.iter().map(|t| {
401 if let UnpackedKind::Type(ty) = t.unpack() {
404 bug!("upvar should be type")
409 /// Returns the type representing the yield type of the generator.
410 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
411 self.split(def_id, tcx).yield_ty
414 /// Returns the type representing the return type of the generator.
415 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
416 self.split(def_id, tcx).return_ty
419 /// Return the "generator signature", which consists of its yield
420 /// and return types.
422 /// NB. Some bits of the code prefers to see this wrapped in a
423 /// binder, but it never contains bound regions. Probably this
424 /// function should be removed.
425 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
426 ty::Binder::dummy(self.sig(def_id, tcx))
429 /// Return the "generator signature", which consists of its yield
430 /// and return types.
431 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
433 yield_ty: self.yield_ty(def_id, tcx),
434 return_ty: self.return_ty(def_id, tcx),
439 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
440 /// This returns the types of the MIR locals which had to be stored across suspension points.
441 /// It is calculated in rustc_mir::transform::generator::StateTransform.
442 /// All the types here must be in the tuple in GeneratorInterior.
446 tcx: TyCtxt<'a, 'gcx, 'tcx>,
447 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
448 let state = tcx.generator_layout(def_id).fields.iter();
449 state.map(move |d| d.ty.subst(tcx, self.substs))
452 /// This is the types of the fields of a generate which
453 /// is available before the generator transformation.
454 /// It includes the upvars and the state discriminant which is u32.
455 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
456 impl Iterator<Item=Ty<'tcx>> + 'a
458 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
461 /// This is the types of all the fields stored in a generator.
462 /// It includes the upvars, state types and the state discriminant which is u32.
463 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
464 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
466 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
470 #[derive(Debug, Copy, Clone)]
471 pub enum UpvarSubsts<'tcx> {
472 Closure(ClosureSubsts<'tcx>),
473 Generator(GeneratorSubsts<'tcx>),
476 impl<'tcx> UpvarSubsts<'tcx> {
478 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
479 impl Iterator<Item=Ty<'tcx>> + 'tcx
481 let upvar_kinds = match self {
482 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
483 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
485 upvar_kinds.iter().map(|t| {
486 if let UnpackedKind::Type(ty) = t.unpack() {
489 bug!("upvar should be type")
495 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
496 pub enum ExistentialPredicate<'tcx> {
498 Trait(ExistentialTraitRef<'tcx>),
499 /// e.g. Iterator::Item = T
500 Projection(ExistentialProjection<'tcx>),
505 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
506 /// Compares via an ordering that will not change if modules are reordered or other changes are
507 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
508 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
509 use self::ExistentialPredicate::*;
510 match (*self, *other) {
511 (Trait(_), Trait(_)) => Ordering::Equal,
512 (Projection(ref a), Projection(ref b)) =>
513 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
514 (AutoTrait(ref a), AutoTrait(ref b)) =>
515 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
516 (Trait(_), _) => Ordering::Less,
517 (Projection(_), Trait(_)) => Ordering::Greater,
518 (Projection(_), _) => Ordering::Less,
519 (AutoTrait(_), _) => Ordering::Greater,
525 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
526 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
527 -> ty::Predicate<'tcx> {
529 match *self.skip_binder() {
530 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
531 ExistentialPredicate::Projection(p) =>
532 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
533 ExistentialPredicate::AutoTrait(did) => {
534 let trait_ref = Binder(ty::TraitRef {
536 substs: tcx.mk_substs_trait(self_ty, &[]),
538 trait_ref.to_predicate()
544 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
546 impl<'tcx> List<ExistentialPredicate<'tcx>> {
547 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
549 Some(&ExistentialPredicate::Trait(tr)) => Some(tr),
555 pub fn projection_bounds<'a>(&'a self) ->
556 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
557 self.iter().filter_map(|predicate| {
559 ExistentialPredicate::Projection(p) => Some(p),
566 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
567 self.iter().filter_map(|predicate| {
569 ExistentialPredicate::AutoTrait(d) => Some(d),
576 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
577 pub fn principal(&self) -> Option<PolyExistentialTraitRef<'tcx>> {
578 self.skip_binder().principal().map(Binder::bind)
582 pub fn projection_bounds<'a>(&'a self) ->
583 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
584 self.skip_binder().projection_bounds().map(Binder::bind)
588 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
589 self.skip_binder().auto_traits()
592 pub fn iter<'a>(&'a self)
593 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
594 self.skip_binder().iter().cloned().map(Binder::bind)
598 /// A complete reference to a trait. These take numerous guises in syntax,
599 /// but perhaps the most recognizable form is in a where clause:
603 /// This would be represented by a trait-reference where the def-id is the
604 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
605 /// and `U` as parameter 1.
607 /// Trait references also appear in object types like `Foo<U>`, but in
608 /// that case the `Self` parameter is absent from the substitutions.
610 /// Note that a `TraitRef` introduces a level of region binding, to
611 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
612 /// U>` or higher-ranked object types.
613 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
614 pub struct TraitRef<'tcx> {
616 pub substs: &'tcx Substs<'tcx>,
619 impl<'tcx> TraitRef<'tcx> {
620 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
621 TraitRef { def_id: def_id, substs: substs }
624 /// Returns a TraitRef of the form `P0: Foo<P1..Pn>` where `Pi`
625 /// are the parameters defined on trait.
626 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
629 substs: Substs::identity_for_item(tcx, def_id),
633 pub fn self_ty(&self) -> Ty<'tcx> {
634 self.substs.type_at(0)
637 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
638 // Select only the "input types" from a trait-reference. For
639 // now this is all the types that appear in the
640 // trait-reference, but it should eventually exclude
645 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
647 substs: &Substs<'tcx>)
648 -> ty::TraitRef<'tcx> {
649 let defs = tcx.generics_of(trait_id);
653 substs: tcx.intern_substs(&substs[..defs.params.len()])
658 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
660 impl<'tcx> PolyTraitRef<'tcx> {
661 pub fn self_ty(&self) -> Ty<'tcx> {
662 self.skip_binder().self_ty()
665 pub fn def_id(&self) -> DefId {
666 self.skip_binder().def_id
669 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
670 // Note that we preserve binding levels
671 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
675 /// An existential reference to a trait, where `Self` is erased.
676 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
678 /// exists T. T: Trait<'a, 'b, X, Y>
680 /// The substitutions don't include the erased `Self`, only trait
681 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
682 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
683 pub struct ExistentialTraitRef<'tcx> {
685 pub substs: &'tcx Substs<'tcx>,
688 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
689 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
690 // Select only the "input types" from a trait-reference. For
691 // now this is all the types that appear in the
692 // trait-reference, but it should eventually exclude
697 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
698 trait_ref: ty::TraitRef<'tcx>)
699 -> ty::ExistentialTraitRef<'tcx> {
700 // Assert there is a Self.
701 trait_ref.substs.type_at(0);
703 ty::ExistentialTraitRef {
704 def_id: trait_ref.def_id,
705 substs: tcx.intern_substs(&trait_ref.substs[1..])
709 /// Object types don't have a self-type specified. Therefore, when
710 /// we convert the principal trait-ref into a normal trait-ref,
711 /// you must give *some* self-type. A common choice is `mk_err()`
712 /// or some skolemized type.
713 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
714 -> ty::TraitRef<'tcx> {
715 // otherwise the escaping regions would be captured by the binder
716 // debug_assert!(!self_ty.has_escaping_regions());
720 substs: tcx.mk_substs_trait(self_ty, self.substs)
725 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
727 impl<'tcx> PolyExistentialTraitRef<'tcx> {
728 pub fn def_id(&self) -> DefId {
729 self.skip_binder().def_id
732 /// Object types don't have a self-type specified. Therefore, when
733 /// we convert the principal trait-ref into a normal trait-ref,
734 /// you must give *some* self-type. A common choice is `mk_err()`
735 /// or some skolemized type.
736 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
738 -> ty::PolyTraitRef<'tcx> {
739 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
743 /// Binder is a binder for higher-ranked lifetimes. It is part of the
744 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
745 /// (which would be represented by the type `PolyTraitRef ==
746 /// Binder<TraitRef>`). Note that when we skolemize, instantiate,
747 /// erase, or otherwise "discharge" these bound regions, we change the
748 /// type from `Binder<T>` to just `T` (see
749 /// e.g. `liberate_late_bound_regions`).
750 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
751 pub struct Binder<T>(T);
754 /// Wraps `value` in a binder, asserting that `value` does not
755 /// contain any bound regions that would be bound by the
756 /// binder. This is commonly used to 'inject' a value T into a
757 /// different binding level.
758 pub fn dummy<'tcx>(value: T) -> Binder<T>
759 where T: TypeFoldable<'tcx>
761 debug_assert!(!value.has_escaping_regions());
765 /// Wraps `value` in a binder, binding late-bound regions (if any).
766 pub fn bind<'tcx>(value: T) -> Binder<T>
771 /// Skips the binder and returns the "bound" value. This is a
772 /// risky thing to do because it's easy to get confused about
773 /// debruijn indices and the like. It is usually better to
774 /// discharge the binder using `no_late_bound_regions` or
775 /// `replace_late_bound_regions` or something like
776 /// that. `skip_binder` is only valid when you are either
777 /// extracting data that has nothing to do with bound regions, you
778 /// are doing some sort of test that does not involve bound
779 /// regions, or you are being very careful about your depth
782 /// Some examples where `skip_binder` is reasonable:
784 /// - extracting the def-id from a PolyTraitRef;
785 /// - comparing the self type of a PolyTraitRef to see if it is equal to
786 /// a type parameter `X`, since the type `X` does not reference any regions
787 pub fn skip_binder(&self) -> &T {
791 pub fn as_ref(&self) -> Binder<&T> {
795 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
796 where F: FnOnce(&T) -> U
798 self.as_ref().map_bound(f)
801 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
802 where F: FnOnce(T) -> U
807 /// Unwraps and returns the value within, but only if it contains
808 /// no bound regions at all. (In other words, if this binder --
809 /// and indeed any enclosing binder -- doesn't bind anything at
810 /// all.) Otherwise, returns `None`.
812 /// (One could imagine having a method that just unwraps a single
813 /// binder, but permits late-bound regions bound by enclosing
814 /// binders, but that would require adjusting the debruijn
815 /// indices, and given the shallow binding structure we often use,
816 /// would not be that useful.)
817 pub fn no_late_bound_regions<'tcx>(self) -> Option<T>
818 where T : TypeFoldable<'tcx>
820 if self.skip_binder().has_escaping_regions() {
823 Some(self.skip_binder().clone())
827 /// Given two things that have the same binder level,
828 /// and an operation that wraps on their contents, execute the operation
829 /// and then wrap its result.
831 /// `f` should consider bound regions at depth 1 to be free, and
832 /// anything it produces with bound regions at depth 1 will be
833 /// bound in the resulting return value.
834 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
835 where F: FnOnce(T, U) -> R
837 Binder(f(self.0, u.0))
840 /// Split the contents into two things that share the same binder
841 /// level as the original, returning two distinct binders.
843 /// `f` should consider bound regions at depth 1 to be free, and
844 /// anything it produces with bound regions at depth 1 will be
845 /// bound in the resulting return values.
846 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
847 where F: FnOnce(T) -> (U, V)
849 let (u, v) = f(self.0);
850 (Binder(u), Binder(v))
854 /// Represents the projection of an associated type. In explicit UFCS
855 /// form this would be written `<T as Trait<..>>::N`.
856 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
857 pub struct ProjectionTy<'tcx> {
858 /// The parameters of the associated item.
859 pub substs: &'tcx Substs<'tcx>,
861 /// The DefId of the TraitItem for the associated type N.
863 /// Note that this is not the DefId of the TraitRef containing this
864 /// associated type, which is in tcx.associated_item(item_def_id).container.
865 pub item_def_id: DefId,
868 impl<'a, 'tcx> ProjectionTy<'tcx> {
869 /// Construct a ProjectionTy by searching the trait from trait_ref for the
870 /// associated item named item_name.
871 pub fn from_ref_and_name(
872 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
873 ) -> ProjectionTy<'tcx> {
874 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
875 item.kind == ty::AssociatedKind::Type &&
876 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
880 substs: trait_ref.substs,
885 /// Extracts the underlying trait reference from this projection.
886 /// For example, if this is a projection of `<T as Iterator>::Item`,
887 /// then this function would return a `T: Iterator` trait reference.
888 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
889 let def_id = tcx.associated_item(self.item_def_id).container.id();
896 pub fn self_ty(&self) -> Ty<'tcx> {
897 self.substs.type_at(0)
901 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
902 pub struct GenSig<'tcx> {
903 pub yield_ty: Ty<'tcx>,
904 pub return_ty: Ty<'tcx>,
907 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
909 impl<'tcx> PolyGenSig<'tcx> {
910 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
911 self.map_bound_ref(|sig| sig.yield_ty)
913 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
914 self.map_bound_ref(|sig| sig.return_ty)
918 /// Signature of a function type, which I have arbitrarily
919 /// decided to use to refer to the input/output types.
921 /// - `inputs` is the list of arguments and their modes.
922 /// - `output` is the return type.
923 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
924 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
925 pub struct FnSig<'tcx> {
926 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
928 pub unsafety: hir::Unsafety,
932 impl<'tcx> FnSig<'tcx> {
933 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
934 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
937 pub fn output(&self) -> Ty<'tcx> {
938 self.inputs_and_output[self.inputs_and_output.len() - 1]
942 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
944 impl<'tcx> PolyFnSig<'tcx> {
945 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
946 self.map_bound_ref(|fn_sig| fn_sig.inputs())
948 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
949 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
951 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
952 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
954 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
955 self.map_bound_ref(|fn_sig| fn_sig.output().clone())
957 pub fn variadic(&self) -> bool {
958 self.skip_binder().variadic
960 pub fn unsafety(&self) -> hir::Unsafety {
961 self.skip_binder().unsafety
963 pub fn abi(&self) -> abi::Abi {
964 self.skip_binder().abi
968 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
971 pub name: InternedString,
974 impl<'a, 'gcx, 'tcx> ParamTy {
975 pub fn new(index: u32, name: InternedString) -> ParamTy {
976 ParamTy { idx: index, name: name }
979 pub fn for_self() -> ParamTy {
980 ParamTy::new(0, keywords::SelfType.name().as_interned_str())
983 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
984 ParamTy::new(def.index, def.name)
987 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
988 tcx.mk_ty_param(self.idx, self.name)
991 pub fn is_self(&self) -> bool {
992 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
993 // but this should only be possible when using `-Z continue-parse-after-error` like
994 // `compile-fail/issue-36638.rs`.
995 if self.name == keywords::SelfType.name().as_str() && self.idx == 0 {
1003 /// A [De Bruijn index][dbi] is a standard means of representing
1004 /// regions (and perhaps later types) in a higher-ranked setting. In
1005 /// particular, imagine a type like this:
1007 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1010 /// | +------------+ 0 | |
1012 /// +--------------------------------+ 1 |
1014 /// +------------------------------------------+ 0
1016 /// In this type, there are two binders (the outer fn and the inner
1017 /// fn). We need to be able to determine, for any given region, which
1018 /// fn type it is bound by, the inner or the outer one. There are
1019 /// various ways you can do this, but a De Bruijn index is one of the
1020 /// more convenient and has some nice properties. The basic idea is to
1021 /// count the number of binders, inside out. Some examples should help
1022 /// clarify what I mean.
1024 /// Let's start with the reference type `&'b isize` that is the first
1025 /// argument to the inner function. This region `'b` is assigned a De
1026 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1027 /// fn). The region `'a` that appears in the second argument type (`&'a
1028 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1029 /// second-innermost binder". (These indices are written on the arrays
1030 /// in the diagram).
1032 /// What is interesting is that De Bruijn index attached to a particular
1033 /// variable will vary depending on where it appears. For example,
1034 /// the final type `&'a char` also refers to the region `'a` declared on
1035 /// the outermost fn. But this time, this reference is not nested within
1036 /// any other binders (i.e., it is not an argument to the inner fn, but
1037 /// rather the outer one). Therefore, in this case, it is assigned a
1038 /// De Bruijn index of 0, because the innermost binder in that location
1039 /// is the outer fn.
1041 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1043 pub struct DebruijnIndex {
1044 DEBUG_FORMAT = "DebruijnIndex({})",
1045 const INNERMOST = 0,
1049 pub type Region<'tcx> = &'tcx RegionKind;
1051 /// Representation of regions.
1053 /// Unlike types, most region variants are "fictitious", not concrete,
1054 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1055 /// ones representing concrete regions.
1057 /// ## Bound Regions
1059 /// These are regions that are stored behind a binder and must be substituted
1060 /// with some concrete region before being used. There are 2 kind of
1061 /// bound regions: early-bound, which are bound in an item's Generics,
1062 /// and are substituted by a Substs, and late-bound, which are part of
1063 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
1064 /// the likes of `liberate_late_bound_regions`. The distinction exists
1065 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1067 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1068 /// outside their binder, e.g. in types passed to type inference, and
1069 /// should first be substituted (by skolemized regions, free regions,
1070 /// or region variables).
1072 /// ## Skolemized and Free Regions
1074 /// One often wants to work with bound regions without knowing their precise
1075 /// identity. For example, when checking a function, the lifetime of a borrow
1076 /// can end up being assigned to some region parameter. In these cases,
1077 /// it must be ensured that bounds on the region can't be accidentally
1078 /// assumed without being checked.
1080 /// The process of doing that is called "skolemization". The bound regions
1081 /// are replaced by skolemized markers, which don't satisfy any relation
1082 /// not explicitly provided.
1084 /// There are 2 kinds of skolemized regions in rustc: `ReFree` and
1085 /// `ReSkolemized`. When checking an item's body, `ReFree` is supposed
1086 /// to be used. These also support explicit bounds: both the internally-stored
1087 /// *scope*, which the region is assumed to outlive, as well as other
1088 /// relations stored in the `FreeRegionMap`. Note that these relations
1089 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1090 /// `resolve_regions_and_report_errors`.
1092 /// When working with higher-ranked types, some region relations aren't
1093 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1094 /// `ReSkolemized` is designed for this purpose. In these contexts,
1095 /// there's also the risk that some inference variable laying around will
1096 /// get unified with your skolemized region: if you want to check whether
1097 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1098 /// with a skolemized region `'%a`, the variable `'_` would just be
1099 /// instantiated to the skolemized region `'%a`, which is wrong because
1100 /// the inference variable is supposed to satisfy the relation
1101 /// *for every value of the skolemized region*. To ensure that doesn't
1102 /// happen, you can use `leak_check`. This is more clearly explained
1103 /// by the [rustc guide].
1105 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1106 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1107 /// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/traits/hrtb.html
1108 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1109 pub enum RegionKind {
1110 // Region bound in a type or fn declaration which will be
1111 // substituted 'early' -- that is, at the same time when type
1112 // parameters are substituted.
1113 ReEarlyBound(EarlyBoundRegion),
1115 // Region bound in a function scope, which will be substituted when the
1116 // function is called.
1117 ReLateBound(DebruijnIndex, BoundRegion),
1119 /// When checking a function body, the types of all arguments and so forth
1120 /// that refer to bound region parameters are modified to refer to free
1121 /// region parameters.
1124 /// A concrete region naming some statically determined scope
1125 /// (e.g. an expression or sequence of statements) within the
1126 /// current function.
1127 ReScope(region::Scope),
1129 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1132 /// A region variable. Should not exist after typeck.
1135 /// A skolemized region - basically the higher-ranked version of ReFree.
1136 /// Should not exist after typeck.
1137 ReSkolemized(ty::UniverseIndex, BoundRegion),
1139 /// Empty lifetime is for data that is never accessed.
1140 /// Bottom in the region lattice. We treat ReEmpty somewhat
1141 /// specially; at least right now, we do not generate instances of
1142 /// it during the GLB computations, but rather
1143 /// generate an error instead. This is to improve error messages.
1144 /// The only way to get an instance of ReEmpty is to have a region
1145 /// variable with no constraints.
1148 /// Erased region, used by trait selection, in MIR and during codegen.
1151 /// These are regions bound in the "defining type" for a
1152 /// closure. They are used ONLY as part of the
1153 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1154 /// See `ClosureRegionRequirements` for more details.
1155 ReClosureBound(RegionVid),
1157 /// Canonicalized region, used only when preparing a trait query.
1158 ReCanonical(CanonicalVar),
1161 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1163 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1164 pub struct EarlyBoundRegion {
1167 pub name: InternedString,
1170 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1175 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1180 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1181 pub struct FloatVid {
1186 pub struct RegionVid {
1187 DEBUG_FORMAT = custom,
1191 impl Atom for RegionVid {
1192 fn index(self) -> usize {
1197 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1203 /// A `FreshTy` is one that is generated as a replacement for an
1204 /// unbound type variable. This is convenient for caching etc. See
1205 /// `infer::freshen` for more details.
1210 /// Canonicalized type variable, used only when preparing a trait query.
1211 CanonicalTy(CanonicalVar),
1215 pub struct CanonicalVar { .. }
1218 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1219 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1220 pub struct ExistentialProjection<'tcx> {
1221 pub item_def_id: DefId,
1222 pub substs: &'tcx Substs<'tcx>,
1226 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1228 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1229 /// Extracts the underlying existential trait reference from this projection.
1230 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1231 /// then this function would return a `exists T. T: Iterator` existential trait
1233 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1234 let def_id = tcx.associated_item(self.item_def_id).container.id();
1235 ty::ExistentialTraitRef{
1237 substs: self.substs,
1241 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1243 -> ty::ProjectionPredicate<'tcx>
1245 // otherwise the escaping regions would be captured by the binders
1246 debug_assert!(!self_ty.has_escaping_regions());
1248 ty::ProjectionPredicate {
1249 projection_ty: ty::ProjectionTy {
1250 item_def_id: self.item_def_id,
1251 substs: tcx.mk_substs_trait(self_ty, self.substs),
1258 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1259 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1260 -> ty::PolyProjectionPredicate<'tcx> {
1261 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1264 pub fn item_def_id(&self) -> DefId {
1265 return self.skip_binder().item_def_id;
1269 impl DebruijnIndex {
1270 /// Returns the resulting index when this value is moved into
1271 /// `amount` number of new binders. So e.g. if you had
1273 /// for<'a> fn(&'a x)
1275 /// and you wanted to change to
1277 /// for<'a> fn(for<'b> fn(&'a x))
1279 /// you would need to shift the index for `'a` into 1 new binder.
1281 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1282 DebruijnIndex::from_u32(self.as_u32() + amount)
1285 /// Update this index in place by shifting it "in" through
1286 /// `amount` number of binders.
1287 pub fn shift_in(&mut self, amount: u32) {
1288 *self = self.shifted_in(amount);
1291 /// Returns the resulting index when this value is moved out from
1292 /// `amount` number of new binders.
1294 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1295 DebruijnIndex::from_u32(self.as_u32() - amount)
1298 /// Update in place by shifting out from `amount` binders.
1299 pub fn shift_out(&mut self, amount: u32) {
1300 *self = self.shifted_out(amount);
1303 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1304 /// innermost binder. That is, if we have something bound at `to_binder`,
1305 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1306 /// when moving a region out from inside binders:
1309 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1310 /// // Binder: D3 D2 D1 ^^
1313 /// Here, the region `'a` would have the debruijn index D3,
1314 /// because it is the bound 3 binders out. However, if we wanted
1315 /// to refer to that region `'a` in the second argument (the `_`),
1316 /// those two binders would not be in scope. In that case, we
1317 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1318 /// debruijn index of `'a` to D1 (the innermost binder).
1320 /// If we invoke `shift_out_to_binder` and the region is in fact
1321 /// bound by one of the binders we are shifting out of, that is an
1322 /// error (and should fail an assertion failure).
1323 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1324 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1328 impl_stable_hash_for!(struct DebruijnIndex { private });
1330 /// Region utilities
1332 /// Is this region named by the user?
1333 pub fn has_name(&self) -> bool {
1335 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1336 RegionKind::ReLateBound(_, br) => br.is_named(),
1337 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1338 RegionKind::ReScope(..) => false,
1339 RegionKind::ReStatic => true,
1340 RegionKind::ReVar(..) => false,
1341 RegionKind::ReSkolemized(_, br) => br.is_named(),
1342 RegionKind::ReEmpty => false,
1343 RegionKind::ReErased => false,
1344 RegionKind::ReClosureBound(..) => false,
1345 RegionKind::ReCanonical(..) => false,
1349 pub fn is_late_bound(&self) -> bool {
1351 ty::ReLateBound(..) => true,
1356 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1358 ty::ReLateBound(debruijn, _) => debruijn >= index,
1363 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1364 /// innermost binder. That is, if we have something bound at `to_binder`,
1365 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1366 /// when moving a region out from inside binders:
1369 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1370 /// // Binder: D3 D2 D1 ^^
1373 /// Here, the region `'a` would have the debruijn index D3,
1374 /// because it is the bound 3 binders out. However, if we wanted
1375 /// to refer to that region `'a` in the second argument (the `_`),
1376 /// those two binders would not be in scope. In that case, we
1377 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1378 /// debruijn index of `'a` to D1 (the innermost binder).
1380 /// If we invoke `shift_out_to_binder` and the region is in fact
1381 /// bound by one of the binders we are shifting out of, that is an
1382 /// error (and should fail an assertion failure).
1383 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1385 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1386 debruijn.shifted_out_to_binder(to_binder),
1393 pub fn keep_in_local_tcx(&self) -> bool {
1394 if let ty::ReVar(..) = self {
1401 pub fn type_flags(&self) -> TypeFlags {
1402 let mut flags = TypeFlags::empty();
1404 if self.keep_in_local_tcx() {
1405 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1410 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1411 flags = flags | TypeFlags::HAS_RE_INFER;
1413 ty::ReSkolemized(..) => {
1414 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1415 flags = flags | TypeFlags::HAS_RE_SKOL;
1417 ty::ReLateBound(..) => {
1418 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1420 ty::ReEarlyBound(..) => {
1421 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1422 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1427 ty::ReScope { .. } => {
1428 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1432 ty::ReCanonical(..) => {
1433 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1434 flags = flags | TypeFlags::HAS_CANONICAL_VARS;
1436 ty::ReClosureBound(..) => {
1437 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1442 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1443 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1446 debug!("type_flags({:?}) = {:?}", self, flags);
1451 /// Given an early-bound or free region, returns the def-id where it was bound.
1452 /// For example, consider the regions in this snippet of code:
1456 /// ^^ -- early bound, declared on an impl
1458 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1459 /// ^^ ^^ ^ anonymous, late-bound
1460 /// | early-bound, appears in where-clauses
1461 /// late-bound, appears only in fn args
1466 /// Here, `free_region_binding_scope('a)` would return the def-id
1467 /// of the impl, and for all the other highlighted regions, it
1468 /// would return the def-id of the function. In other cases (not shown), this
1469 /// function might return the def-id of a closure.
1470 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1472 ty::ReEarlyBound(br) => {
1473 tcx.parent_def_id(br.def_id).unwrap()
1475 ty::ReFree(fr) => fr.scope,
1476 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1482 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1483 pub fn is_unit(&self) -> bool {
1485 Tuple(ref tys) => tys.is_empty(),
1490 pub fn is_never(&self) -> bool {
1497 pub fn is_primitive(&self) -> bool {
1499 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1504 pub fn is_ty_var(&self) -> bool {
1506 Infer(TyVar(_)) => true,
1511 pub fn is_ty_infer(&self) -> bool {
1518 pub fn is_phantom_data(&self) -> bool {
1519 if let Adt(def, _) = self.sty {
1520 def.is_phantom_data()
1526 pub fn is_bool(&self) -> bool { self.sty == Bool }
1528 pub fn is_param(&self, index: u32) -> bool {
1530 ty::Param(ref data) => data.idx == index,
1535 pub fn is_self(&self) -> bool {
1537 Param(ref p) => p.is_self(),
1542 pub fn is_slice(&self) -> bool {
1544 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1545 Slice(_) | Str => true,
1553 pub fn is_simd(&self) -> bool {
1555 Adt(def, _) => def.repr.simd(),
1560 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1562 Array(ty, _) | Slice(ty) => ty,
1563 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1564 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1568 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1570 Adt(def, substs) => {
1571 def.non_enum_variant().fields[0].ty(tcx, substs)
1573 _ => bug!("simd_type called on invalid type")
1577 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1579 Adt(def, _) => def.non_enum_variant().fields.len(),
1580 _ => bug!("simd_size called on invalid type")
1584 pub fn is_region_ptr(&self) -> bool {
1591 pub fn is_mutable_pointer(&self) -> bool {
1593 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1594 Ref(_, _, hir::Mutability::MutMutable) => true,
1599 pub fn is_unsafe_ptr(&self) -> bool {
1601 RawPtr(_) => return true,
1606 pub fn is_box(&self) -> bool {
1608 Adt(def, _) => def.is_box(),
1613 /// panics if called on any type other than `Box<T>`
1614 pub fn boxed_ty(&self) -> Ty<'tcx> {
1616 Adt(def, substs) if def.is_box() => substs.type_at(0),
1617 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1621 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1622 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1623 /// contents are abstract to rustc.)
1624 pub fn is_scalar(&self) -> bool {
1626 Bool | Char | Int(_) | Float(_) | Uint(_) |
1627 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1628 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1633 /// Returns true if this type is a floating point type and false otherwise.
1634 pub fn is_floating_point(&self) -> bool {
1637 Infer(FloatVar(_)) => true,
1642 pub fn is_trait(&self) -> bool {
1644 Dynamic(..) => true,
1649 pub fn is_enum(&self) -> bool {
1651 Adt(adt_def, _) => {
1658 pub fn is_closure(&self) -> bool {
1660 Closure(..) => true,
1665 pub fn is_generator(&self) -> bool {
1667 Generator(..) => true,
1672 pub fn is_integral(&self) -> bool {
1674 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1679 pub fn is_fresh_ty(&self) -> bool {
1681 Infer(FreshTy(_)) => true,
1686 pub fn is_fresh(&self) -> bool {
1688 Infer(FreshTy(_)) => true,
1689 Infer(FreshIntTy(_)) => true,
1690 Infer(FreshFloatTy(_)) => true,
1695 pub fn is_char(&self) -> bool {
1702 pub fn is_fp(&self) -> bool {
1704 Infer(FloatVar(_)) | Float(_) => true,
1709 pub fn is_numeric(&self) -> bool {
1710 self.is_integral() || self.is_fp()
1713 pub fn is_signed(&self) -> bool {
1720 pub fn is_machine(&self) -> bool {
1722 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1723 Int(..) | Uint(..) | Float(..) => true,
1728 pub fn has_concrete_skeleton(&self) -> bool {
1730 Param(_) | Infer(_) | Error => false,
1735 /// Returns the type and mutability of *ty.
1737 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1738 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1739 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1741 Adt(def, _) if def.is_box() => {
1743 ty: self.boxed_ty(),
1744 mutbl: hir::MutImmutable,
1747 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1748 RawPtr(mt) if explicit => Some(mt),
1753 /// Returns the type of `ty[i]`.
1754 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1756 Array(ty, _) | Slice(ty) => Some(ty),
1761 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1763 FnDef(def_id, substs) => {
1764 tcx.fn_sig(def_id).subst(tcx, substs)
1767 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1771 pub fn is_fn(&self) -> bool {
1773 FnDef(..) | FnPtr(_) => true,
1778 pub fn is_impl_trait(&self) -> bool {
1785 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1787 Adt(adt, _) => Some(adt),
1792 /// Returns the regions directly referenced from this type (but
1793 /// not types reachable from this type via `walk_tys`). This
1794 /// ignores late-bound regions binders.
1795 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1797 Ref(region, _, _) => {
1800 Dynamic(ref obj, region) => {
1801 let mut v = vec![region];
1802 if let Some(p) = obj.principal() {
1803 v.extend(p.skip_binder().substs.regions());
1807 Adt(_, substs) | Opaque(_, substs) => {
1808 substs.regions().collect()
1810 Closure(_, ClosureSubsts { ref substs }) |
1811 Generator(_, GeneratorSubsts { ref substs }, _) => {
1812 substs.regions().collect()
1814 Projection(ref data) | UnnormalizedProjection(ref data) => {
1815 data.substs.regions().collect()
1819 GeneratorWitness(..) |
1840 /// When we create a closure, we record its kind (i.e., what trait
1841 /// it implements) into its `ClosureSubsts` using a type
1842 /// parameter. This is kind of a phantom type, except that the
1843 /// most convenient thing for us to are the integral types. This
1844 /// function converts such a special type into the closure
1845 /// kind. To go the other way, use
1846 /// `tcx.closure_kind_ty(closure_kind)`.
1848 /// Note that during type checking, we use an inference variable
1849 /// to represent the closure kind, because it has not yet been
1850 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1851 /// is complete, that type variable will be unified.
1852 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1854 Int(int_ty) => match int_ty {
1855 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1856 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1857 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1858 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1863 Error => Some(ty::ClosureKind::Fn),
1865 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1869 /// Fast path helper for testing if a type is `Sized`.
1871 /// Returning true means the type is known to be sized. Returning
1872 /// `false` means nothing -- could be sized, might not be.
1873 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1875 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1876 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1877 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1878 ty::Char | ty::Ref(..) | ty::Generator(..) |
1879 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1880 ty::Never | ty::Error =>
1883 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
1887 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
1889 ty::Adt(def, _substs) =>
1890 def.sized_constraint(tcx).is_empty(),
1892 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
1894 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
1896 ty::Infer(ty::TyVar(_)) => false,
1898 ty::Infer(ty::CanonicalTy(_)) |
1899 ty::Infer(ty::FreshTy(_)) |
1900 ty::Infer(ty::FreshIntTy(_)) |
1901 ty::Infer(ty::FreshFloatTy(_)) =>
1902 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
1907 /// Typed constant value.
1908 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
1909 pub struct Const<'tcx> {
1912 pub val: ConstValue<'tcx>,
1915 impl<'tcx> Const<'tcx> {
1917 tcx: TyCtxt<'_, '_, 'tcx>,
1919 substs: &'tcx Substs<'tcx>,
1922 tcx.mk_const(Const {
1923 val: ConstValue::Unevaluated(def_id, substs),
1929 pub fn from_const_value(
1930 tcx: TyCtxt<'_, '_, 'tcx>,
1931 val: ConstValue<'tcx>,
1934 tcx.mk_const(Const {
1942 tcx: TyCtxt<'_, '_, 'tcx>,
1946 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
1951 tcx: TyCtxt<'_, '_, 'tcx>,
1953 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
1955 let ty = tcx.lift_to_global(&ty).unwrap();
1956 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
1957 panic!("could not compute layout for {:?}: {:?}", ty, e)
1959 let shift = 128 - size.bits();
1960 let truncated = (bits << shift) >> shift;
1961 assert_eq!(truncated, bits, "from_bits called with untruncated value");
1962 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
1966 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
1967 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
1971 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
1972 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
1976 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
1977 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
1983 tcx: TyCtxt<'_, '_, 'tcx>,
1984 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
1986 if self.ty != ty.value {
1989 let ty = tcx.lift_to_global(&ty).unwrap();
1990 let size = tcx.layout_of(ty).ok()?.size;
1991 self.val.try_to_bits(size)
1995 pub fn to_ptr(&self) -> Option<Pointer> {
1996 self.val.try_to_ptr()
2002 tcx: TyCtxt<'_, '_, '_>,
2003 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2005 assert_eq!(self.ty, ty.value);
2006 let ty = tcx.lift_to_global(&ty).unwrap();
2007 let size = tcx.layout_of(ty).ok()?.size;
2008 self.val.try_to_bits(size)
2012 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2013 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2021 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2022 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2028 tcx: TyCtxt<'_, '_, '_>,
2029 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2031 match self.assert_bits(tcx, ty) {
2033 None => bug!("expected bits of {}, got {:#?}", ty.value, self),
2038 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2039 match self.assert_usize(tcx) {
2041 None => bug!("expected constant usize, got {:#?}", self),
2046 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}