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;
14 use infer::canonical::Canonical;
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};
25 use smallvec::SmallVec;
27 use std::cmp::Ordering;
28 use rustc_target::spec::abi;
29 use syntax::ast::{self, Ident};
30 use syntax::symbol::{keywords, InternedString};
32 use serialize::{self, Decodable, Decoder};
39 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
40 pub struct TypeAndMut<'tcx> {
42 pub mutbl: hir::Mutability,
45 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
46 RustcEncodable, RustcDecodable, Copy)]
47 /// A "free" region `fr` can be interpreted as "some region
48 /// at least as big as the scope `fr.scope`".
49 pub struct FreeRegion {
51 pub bound_region: BoundRegion,
54 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
55 RustcEncodable, RustcDecodable, Copy)]
56 pub enum BoundRegion {
57 /// An anonymous region parameter for a given fn (&T)
60 /// Named region parameters for functions (a in &'a T)
62 /// The def-id is needed to distinguish free regions in
63 /// the event of shadowing.
64 BrNamed(DefId, InternedString),
66 /// Fresh bound identifiers created during GLB computations.
69 /// Anonymous region for the implicit env pointer parameter
75 pub fn is_named(&self) -> bool {
77 BoundRegion::BrNamed(..) => true,
82 /// When canonicalizing, we replace unbound inference variables and free
83 /// regions with anonymous late bound regions. This method asserts that
84 /// we have an anonymous late bound region, which hence may refer to
85 /// a canonical variable.
86 pub fn assert_bound_var(&self) -> BoundVar {
88 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
89 _ => bug!("bound region is not anonymous"),
94 /// N.B., If you change this, you'll probably want to change the corresponding
95 /// AST structure in `libsyntax/ast.rs` as well.
96 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
97 pub enum TyKind<'tcx> {
98 /// The primitive boolean type. Written as `bool`.
101 /// The primitive character type; holds a Unicode scalar value
102 /// (a non-surrogate code point). Written as `char`.
105 /// A primitive signed integer type. For example, `i32`.
108 /// A primitive unsigned integer type. For example, `u32`.
111 /// A primitive floating-point type. For example, `f64`.
114 /// Structures, enumerations and unions.
116 /// Substs here, possibly against intuition, *may* contain `Param`s.
117 /// That is, even after substitution it is possible that there are type
118 /// variables. This happens when the `Adt` corresponds to an ADT
119 /// definition and not a concrete use of it.
120 Adt(&'tcx AdtDef, &'tcx Substs<'tcx>),
124 /// The pointee of a string slice. Written as `str`.
127 /// An array with the given length. Written as `[T; n]`.
128 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
130 /// The pointee of an array slice. Written as `[T]`.
133 /// A raw pointer. Written as `*mut T` or `*const T`
134 RawPtr(TypeAndMut<'tcx>),
136 /// A reference; a pointer with an associated lifetime. Written as
137 /// `&'a mut T` or `&'a T`.
138 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
140 /// The anonymous type of a function declaration/definition. Each
141 /// function has a unique type, which is output (for a function
142 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
144 /// For example the type of `bar` here:
147 /// fn foo() -> i32 { 1 }
148 /// let bar = foo; // bar: fn() -> i32 {foo}
150 FnDef(DefId, &'tcx Substs<'tcx>),
152 /// A pointer to a function. Written as `fn() -> i32`.
154 /// For example the type of `bar` here:
157 /// fn foo() -> i32 { 1 }
158 /// let bar: fn() -> i32 = foo;
160 FnPtr(PolyFnSig<'tcx>),
162 /// A trait, defined with `trait`.
163 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
165 /// The anonymous type of a closure. Used to represent the type of
167 Closure(DefId, ClosureSubsts<'tcx>),
169 /// The anonymous type of a generator. Used to represent the type of
171 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
173 /// A type representin the types stored inside a generator.
174 /// This should only appear in GeneratorInteriors.
175 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
177 /// The never type `!`
180 /// A tuple type. For example, `(i32, bool)`.
181 Tuple(&'tcx List<Ty<'tcx>>),
183 /// The projection of an associated type. For example,
184 /// `<T as Trait<..>>::N`.
185 Projection(ProjectionTy<'tcx>),
187 /// A placeholder type used when we do not have enough information
188 /// to normalize the projection of an associated type to an
189 /// existing concrete type. Currently only used with chalk-engine.
190 UnnormalizedProjection(ProjectionTy<'tcx>),
192 /// Opaque (`impl Trait`) type found in a return type.
193 /// The `DefId` comes either from
194 /// * the `impl Trait` ast::Ty node,
195 /// * or the `existential type` declaration
196 /// The substitutions are for the generics of the function in question.
197 /// After typeck, the concrete type can be found in the `types` map.
198 Opaque(DefId, &'tcx Substs<'tcx>),
200 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
203 /// Bound type variable, used only when preparing a trait query.
204 Bound(ty::DebruijnIndex, BoundTy),
206 /// A placeholder type - universally quantified higher-ranked type.
207 Placeholder(ty::PlaceholderType),
209 /// A type variable used during type checking.
212 /// A placeholder for a type which could not be computed; this is
213 /// propagated to avoid useless error messages.
217 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
218 #[cfg(target_arch = "x86_64")]
219 static_assert!(MEM_SIZE_OF_TY_KIND: ::std::mem::size_of::<TyKind<'_>>() == 24);
221 /// A closure can be modeled as a struct that looks like:
223 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
231 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
232 /// in scope on the function that defined the closure,
233 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
234 /// is rather hackily encoded via a scalar type. See
235 /// `TyS::to_opt_closure_kind` for details.
236 /// - CS represents the *closure signature*, representing as a `fn()`
237 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
238 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
240 /// - U0...Uk are type parameters representing the types of its upvars
241 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
242 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
244 /// So, for example, given this function:
246 /// fn foo<'a, T>(data: &'a mut T) {
247 /// do(|| data.count += 1)
250 /// the type of the closure would be something like:
252 /// struct Closure<'a, T, U0> {
256 /// Note that the type of the upvar is not specified in the struct.
257 /// You may wonder how the impl would then be able to use the upvar,
258 /// if it doesn't know it's type? The answer is that the impl is
259 /// (conceptually) not fully generic over Closure but rather tied to
260 /// instances with the expected upvar types:
262 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
266 /// You can see that the *impl* fully specified the type of the upvar
267 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
268 /// (Here, I am assuming that `data` is mut-borrowed.)
270 /// Now, the last question you may ask is: Why include the upvar types
271 /// as extra type parameters? The reason for this design is that the
272 /// upvar types can reference lifetimes that are internal to the
273 /// creating function. In my example above, for example, the lifetime
274 /// `'b` represents the scope of the closure itself; this is some
275 /// subset of `foo`, probably just the scope of the call to the to
276 /// `do()`. If we just had the lifetime/type parameters from the
277 /// enclosing function, we couldn't name this lifetime `'b`. Note that
278 /// there can also be lifetimes in the types of the upvars themselves,
279 /// if one of them happens to be a reference to something that the
280 /// creating fn owns.
282 /// OK, you say, so why not create a more minimal set of parameters
283 /// that just includes the extra lifetime parameters? The answer is
284 /// primarily that it would be hard --- we don't know at the time when
285 /// we create the closure type what the full types of the upvars are,
286 /// nor do we know which are borrowed and which are not. In this
287 /// design, we can just supply a fresh type parameter and figure that
290 /// All right, you say, but why include the type parameters from the
291 /// original function then? The answer is that codegen may need them
292 /// when monomorphizing, and they may not appear in the upvars. A
293 /// closure could capture no variables but still make use of some
294 /// in-scope type parameter with a bound (e.g., if our example above
295 /// had an extra `U: Default`, and the closure called `U::default()`).
297 /// There is another reason. This design (implicitly) prohibits
298 /// closures from capturing themselves (except via a trait
299 /// object). This simplifies closure inference considerably, since it
300 /// means that when we infer the kind of a closure or its upvars, we
301 /// don't have to handle cycles where the decisions we make for
302 /// closure C wind up influencing the decisions we ought to make for
303 /// closure C (which would then require fixed point iteration to
304 /// handle). Plus it fixes an ICE. :P
308 /// Perhaps surprisingly, `ClosureSubsts` are also used for
309 /// generators. In that case, what is written above is only half-true
310 /// -- the set of type parameters is similar, but the role of CK and
311 /// CS are different. CK represents the "yield type" and CS
312 /// represents the "return type" of the generator.
314 /// It'd be nice to split this struct into ClosureSubsts and
315 /// GeneratorSubsts, I believe. -nmatsakis
316 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
317 pub struct ClosureSubsts<'tcx> {
318 /// Lifetime and type parameters from the enclosing function,
319 /// concatenated with the types of the upvars.
321 /// These are separated out because codegen wants to pass them around
322 /// when monomorphizing.
323 pub substs: &'tcx Substs<'tcx>,
326 /// Struct returned by `split()`. Note that these are subslices of the
327 /// parent slice and not canonical substs themselves.
328 struct SplitClosureSubsts<'tcx> {
329 closure_kind_ty: Ty<'tcx>,
330 closure_sig_ty: Ty<'tcx>,
331 upvar_kinds: &'tcx [Kind<'tcx>],
334 impl<'tcx> ClosureSubsts<'tcx> {
335 /// Divides the closure substs into their respective
336 /// components. Single source of truth with respect to the
338 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
339 let generics = tcx.generics_of(def_id);
340 let parent_len = generics.parent_count;
342 closure_kind_ty: self.substs.type_at(parent_len),
343 closure_sig_ty: self.substs.type_at(parent_len + 1),
344 upvar_kinds: &self.substs[parent_len + 2..],
349 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
350 impl Iterator<Item=Ty<'tcx>> + 'tcx
352 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
353 upvar_kinds.iter().map(|t| {
354 if let UnpackedKind::Type(ty) = t.unpack() {
357 bug!("upvar should be type")
362 /// Returns the closure kind for this closure; may return a type
363 /// variable during inference. To get the closure kind during
364 /// inference, use `infcx.closure_kind(def_id, substs)`.
365 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
366 self.split(def_id, tcx).closure_kind_ty
369 /// Returns the type representing the closure signature for this
370 /// closure; may contain type variables during inference. To get
371 /// the closure signature during inference, use
372 /// `infcx.fn_sig(def_id)`.
373 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
374 self.split(def_id, tcx).closure_sig_ty
377 /// Returns the closure kind for this closure; only usable outside
378 /// of an inference context, because in that context we know that
379 /// there are no type variables.
381 /// If you have an inference context, use `infcx.closure_kind()`.
382 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
383 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
386 /// Extracts the signature from the closure; only usable outside
387 /// of an inference context, because in that context we know that
388 /// there are no type variables.
390 /// If you have an inference context, use `infcx.closure_sig()`.
391 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
392 match self.closure_sig_ty(def_id, tcx).sty {
393 ty::FnPtr(sig) => sig,
394 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
399 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
400 pub struct GeneratorSubsts<'tcx> {
401 pub substs: &'tcx Substs<'tcx>,
404 struct SplitGeneratorSubsts<'tcx> {
408 upvar_kinds: &'tcx [Kind<'tcx>],
411 impl<'tcx> GeneratorSubsts<'tcx> {
412 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
413 let generics = tcx.generics_of(def_id);
414 let parent_len = generics.parent_count;
415 SplitGeneratorSubsts {
416 yield_ty: self.substs.type_at(parent_len),
417 return_ty: self.substs.type_at(parent_len + 1),
418 witness: self.substs.type_at(parent_len + 2),
419 upvar_kinds: &self.substs[parent_len + 3..],
423 /// This describes the types that can be contained in a generator.
424 /// It will be a type variable initially and unified in the last stages of typeck of a body.
425 /// It contains a tuple of all the types that could end up on a generator frame.
426 /// The state transformation MIR pass may only produce layouts which mention types
427 /// in this tuple. Upvars are not counted here.
428 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
429 self.split(def_id, tcx).witness
433 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
434 impl Iterator<Item=Ty<'tcx>> + 'tcx
436 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
437 upvar_kinds.iter().map(|t| {
438 if let UnpackedKind::Type(ty) = t.unpack() {
441 bug!("upvar should be type")
446 /// Returns the type representing the yield type of the generator.
447 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
448 self.split(def_id, tcx).yield_ty
451 /// Returns the type representing the return type of the generator.
452 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
453 self.split(def_id, tcx).return_ty
456 /// Return the "generator signature", which consists of its yield
457 /// and return types.
459 /// NB. Some bits of the code prefers to see this wrapped in a
460 /// binder, but it never contains bound regions. Probably this
461 /// function should be removed.
462 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
463 ty::Binder::dummy(self.sig(def_id, tcx))
466 /// Return the "generator signature", which consists of its yield
467 /// and return types.
468 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
470 yield_ty: self.yield_ty(def_id, tcx),
471 return_ty: self.return_ty(def_id, tcx),
476 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
477 /// This returns the types of the MIR locals which had to be stored across suspension points.
478 /// It is calculated in rustc_mir::transform::generator::StateTransform.
479 /// All the types here must be in the tuple in GeneratorInterior.
483 tcx: TyCtxt<'a, 'gcx, 'tcx>,
484 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
485 let state = tcx.generator_layout(def_id).fields.iter();
486 state.map(move |d| d.ty.subst(tcx, self.substs))
489 /// This is the types of the fields of a generate which
490 /// is available before the generator transformation.
491 /// It includes the upvars and the state discriminant which is u32.
492 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
493 impl Iterator<Item=Ty<'tcx>> + 'a
495 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
498 /// This is the types of all the fields stored in a generator.
499 /// It includes the upvars, state types and the state discriminant which is u32.
500 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
501 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
503 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
507 #[derive(Debug, Copy, Clone)]
508 pub enum UpvarSubsts<'tcx> {
509 Closure(ClosureSubsts<'tcx>),
510 Generator(GeneratorSubsts<'tcx>),
513 impl<'tcx> UpvarSubsts<'tcx> {
515 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
516 impl Iterator<Item=Ty<'tcx>> + 'tcx
518 let upvar_kinds = match self {
519 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
520 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
522 upvar_kinds.iter().map(|t| {
523 if let UnpackedKind::Type(ty) = t.unpack() {
526 bug!("upvar should be type")
532 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
533 pub enum ExistentialPredicate<'tcx> {
535 Trait(ExistentialTraitRef<'tcx>),
536 /// e.g. Iterator::Item = T
537 Projection(ExistentialProjection<'tcx>),
542 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
543 /// Compares via an ordering that will not change if modules are reordered or other changes are
544 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
545 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
546 use self::ExistentialPredicate::*;
547 match (*self, *other) {
548 (Trait(_), Trait(_)) => Ordering::Equal,
549 (Projection(ref a), Projection(ref b)) =>
550 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
551 (AutoTrait(ref a), AutoTrait(ref b)) =>
552 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
553 (Trait(_), _) => Ordering::Less,
554 (Projection(_), Trait(_)) => Ordering::Greater,
555 (Projection(_), _) => Ordering::Less,
556 (AutoTrait(_), _) => Ordering::Greater,
562 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
563 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
564 -> ty::Predicate<'tcx> {
566 match *self.skip_binder() {
567 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
568 ExistentialPredicate::Projection(p) =>
569 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
570 ExistentialPredicate::AutoTrait(did) => {
571 let trait_ref = Binder(ty::TraitRef {
573 substs: tcx.mk_substs_trait(self_ty, &[]),
575 trait_ref.to_predicate()
581 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
583 impl<'tcx> List<ExistentialPredicate<'tcx>> {
584 pub fn principal(&self) -> ExistentialTraitRef<'tcx> {
586 ExistentialPredicate::Trait(tr) => tr,
587 other => bug!("first predicate is {:?}", other),
592 pub fn projection_bounds<'a>(&'a self) ->
593 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
594 self.iter().filter_map(|predicate| {
596 ExistentialPredicate::Projection(p) => Some(p),
603 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
604 self.iter().filter_map(|predicate| {
606 ExistentialPredicate::AutoTrait(d) => Some(d),
613 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
614 pub fn principal(&self) -> PolyExistentialTraitRef<'tcx> {
615 Binder::bind(self.skip_binder().principal())
619 pub fn projection_bounds<'a>(&'a self) ->
620 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
621 self.skip_binder().projection_bounds().map(Binder::bind)
625 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
626 self.skip_binder().auto_traits()
629 pub fn iter<'a>(&'a self)
630 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
631 self.skip_binder().iter().cloned().map(Binder::bind)
635 /// A complete reference to a trait. These take numerous guises in syntax,
636 /// but perhaps the most recognizable form is in a where clause:
640 /// This would be represented by a trait-reference where the def-id is the
641 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
642 /// and `U` as parameter 1.
644 /// Trait references also appear in object types like `Foo<U>`, but in
645 /// that case the `Self` parameter is absent from the substitutions.
647 /// Note that a `TraitRef` introduces a level of region binding, to
648 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
649 /// or higher-ranked object types.
650 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
651 pub struct TraitRef<'tcx> {
653 pub substs: &'tcx Substs<'tcx>,
656 impl<'tcx> TraitRef<'tcx> {
657 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
658 TraitRef { def_id: def_id, substs: substs }
661 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
662 /// are the parameters defined on trait.
663 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
666 substs: Substs::identity_for_item(tcx, def_id),
671 pub fn self_ty(&self) -> Ty<'tcx> {
672 self.substs.type_at(0)
675 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
676 // Select only the "input types" from a trait-reference. For
677 // now this is all the types that appear in the
678 // trait-reference, but it should eventually exclude
683 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
685 substs: &Substs<'tcx>)
686 -> ty::TraitRef<'tcx> {
687 let defs = tcx.generics_of(trait_id);
691 substs: tcx.intern_substs(&substs[..defs.params.len()])
696 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
698 impl<'tcx> PolyTraitRef<'tcx> {
699 pub fn self_ty(&self) -> Ty<'tcx> {
700 self.skip_binder().self_ty()
703 pub fn def_id(&self) -> DefId {
704 self.skip_binder().def_id
707 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
708 // Note that we preserve binding levels
709 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
713 /// An existential reference to a trait, where `Self` is erased.
714 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
716 /// exists T. T: Trait<'a, 'b, X, Y>
718 /// The substitutions don't include the erased `Self`, only trait
719 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
720 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
721 pub struct ExistentialTraitRef<'tcx> {
723 pub substs: &'tcx Substs<'tcx>,
726 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
727 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
728 // Select only the "input types" from a trait-reference. For
729 // now this is all the types that appear in the
730 // trait-reference, but it should eventually exclude
735 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
736 trait_ref: ty::TraitRef<'tcx>)
737 -> ty::ExistentialTraitRef<'tcx> {
738 // Assert there is a Self.
739 trait_ref.substs.type_at(0);
741 ty::ExistentialTraitRef {
742 def_id: trait_ref.def_id,
743 substs: tcx.intern_substs(&trait_ref.substs[1..])
747 /// Object types don't have a self-type specified. Therefore, when
748 /// we convert the principal trait-ref into a normal trait-ref,
749 /// you must give *some* self-type. A common choice is `mk_err()`
750 /// or some placeholder type.
751 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
752 -> ty::TraitRef<'tcx> {
753 // otherwise the escaping vars would be captured by the binder
754 // debug_assert!(!self_ty.has_escaping_bound_vars());
758 substs: tcx.mk_substs_trait(self_ty, self.substs)
763 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
765 impl<'tcx> PolyExistentialTraitRef<'tcx> {
766 pub fn def_id(&self) -> DefId {
767 self.skip_binder().def_id
770 /// Object types don't have a self-type specified. Therefore, when
771 /// we convert the principal trait-ref into a normal trait-ref,
772 /// you must give *some* self-type. A common choice is `mk_err()`
773 /// or some placeholder type.
774 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
776 -> ty::PolyTraitRef<'tcx> {
777 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
781 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
782 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
783 /// (which would be represented by the type `PolyTraitRef ==
784 /// Binder<TraitRef>`). Note that when we instantiate,
785 /// erase, or otherwise "discharge" these bound vars, we change the
786 /// type from `Binder<T>` to just `T` (see
787 /// e.g. `liberate_late_bound_regions`).
788 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
789 pub struct Binder<T>(T);
792 /// Wraps `value` in a binder, asserting that `value` does not
793 /// contain any bound vars that would be bound by the
794 /// binder. This is commonly used to 'inject' a value T into a
795 /// different binding level.
796 pub fn dummy<'tcx>(value: T) -> Binder<T>
797 where T: TypeFoldable<'tcx>
799 debug_assert!(!value.has_escaping_bound_vars());
803 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
804 pub fn bind<'tcx>(value: T) -> Binder<T> {
808 /// Skips the binder and returns the "bound" value. This is a
809 /// risky thing to do because it's easy to get confused about
810 /// debruijn indices and the like. It is usually better to
811 /// discharge the binder using `no_bound_vars` or
812 /// `replace_late_bound_regions` or something like
813 /// that. `skip_binder` is only valid when you are either
814 /// extracting data that has nothing to do with bound vars, you
815 /// are doing some sort of test that does not involve bound
816 /// regions, or you are being very careful about your depth
819 /// Some examples where `skip_binder` is reasonable:
821 /// - extracting the def-id from a PolyTraitRef;
822 /// - comparing the self type of a PolyTraitRef to see if it is equal to
823 /// a type parameter `X`, since the type `X` does not reference any regions
824 pub fn skip_binder(&self) -> &T {
828 pub fn as_ref(&self) -> Binder<&T> {
832 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
833 where F: FnOnce(&T) -> U
835 self.as_ref().map_bound(f)
838 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
839 where F: FnOnce(T) -> U
844 /// Unwraps and returns the value within, but only if it contains
845 /// no bound vars at all. (In other words, if this binder --
846 /// and indeed any enclosing binder -- doesn't bind anything at
847 /// all.) Otherwise, returns `None`.
849 /// (One could imagine having a method that just unwraps a single
850 /// binder, but permits late-bound vars bound by enclosing
851 /// binders, but that would require adjusting the debruijn
852 /// indices, and given the shallow binding structure we often use,
853 /// would not be that useful.)
854 pub fn no_bound_vars<'tcx>(self) -> Option<T>
855 where T: TypeFoldable<'tcx>
857 if self.skip_binder().has_escaping_bound_vars() {
860 Some(self.skip_binder().clone())
864 /// Given two things that have the same binder level,
865 /// and an operation that wraps on their contents, execute the operation
866 /// and then wrap its result.
868 /// `f` should consider bound regions at depth 1 to be free, and
869 /// anything it produces with bound regions at depth 1 will be
870 /// bound in the resulting return value.
871 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
872 where F: FnOnce(T, U) -> R
874 Binder(f(self.0, u.0))
877 /// Split the contents into two things that share the same binder
878 /// level as the original, returning two distinct binders.
880 /// `f` should consider bound regions at depth 1 to be free, and
881 /// anything it produces with bound regions at depth 1 will be
882 /// bound in the resulting return values.
883 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
884 where F: FnOnce(T) -> (U, V)
886 let (u, v) = f(self.0);
887 (Binder(u), Binder(v))
891 /// Represents the projection of an associated type. In explicit UFCS
892 /// form this would be written `<T as Trait<..>>::N`.
893 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
894 pub struct ProjectionTy<'tcx> {
895 /// The parameters of the associated item.
896 pub substs: &'tcx Substs<'tcx>,
898 /// The `DefId` of the `TraitItem` for the associated type `N`.
900 /// Note that this is not the `DefId` of the `TraitRef` containing this
901 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
902 pub item_def_id: DefId,
905 impl<'a, 'tcx> ProjectionTy<'tcx> {
906 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
907 /// associated item named `item_name`.
908 pub fn from_ref_and_name(
909 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
910 ) -> ProjectionTy<'tcx> {
911 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
912 item.kind == ty::AssociatedKind::Type &&
913 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
917 substs: trait_ref.substs,
922 /// Extracts the underlying trait reference from this projection.
923 /// For example, if this is a projection of `<T as Iterator>::Item`,
924 /// then this function would return a `T: Iterator` trait reference.
925 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
926 let def_id = tcx.associated_item(self.item_def_id).container.id();
933 pub fn self_ty(&self) -> Ty<'tcx> {
934 self.substs.type_at(0)
938 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
939 pub struct GenSig<'tcx> {
940 pub yield_ty: Ty<'tcx>,
941 pub return_ty: Ty<'tcx>,
944 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
946 impl<'tcx> PolyGenSig<'tcx> {
947 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
948 self.map_bound_ref(|sig| sig.yield_ty)
950 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
951 self.map_bound_ref(|sig| sig.return_ty)
955 /// Signature of a function type, which I have arbitrarily
956 /// decided to use to refer to the input/output types.
958 /// - `inputs` is the list of arguments and their modes.
959 /// - `output` is the return type.
960 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
961 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
962 pub struct FnSig<'tcx> {
963 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
965 pub unsafety: hir::Unsafety,
969 impl<'tcx> FnSig<'tcx> {
970 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
971 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
974 pub fn output(&self) -> Ty<'tcx> {
975 self.inputs_and_output[self.inputs_and_output.len() - 1]
979 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
981 impl<'tcx> PolyFnSig<'tcx> {
983 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
984 self.map_bound_ref(|fn_sig| fn_sig.inputs())
987 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
988 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
990 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
991 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
994 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
995 self.map_bound_ref(|fn_sig| fn_sig.output())
997 pub fn variadic(&self) -> bool {
998 self.skip_binder().variadic
1000 pub fn unsafety(&self) -> hir::Unsafety {
1001 self.skip_binder().unsafety
1003 pub fn abi(&self) -> abi::Abi {
1004 self.skip_binder().abi
1008 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1011 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1012 pub struct ParamTy {
1014 pub name: InternedString,
1017 impl<'a, 'gcx, 'tcx> ParamTy {
1018 pub fn new(index: u32, name: InternedString) -> ParamTy {
1019 ParamTy { idx: index, name: name }
1022 pub fn for_self() -> ParamTy {
1023 ParamTy::new(0, keywords::SelfType.name().as_interned_str())
1026 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1027 ParamTy::new(def.index, def.name)
1030 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1031 tcx.mk_ty_param(self.idx, self.name)
1034 pub fn is_self(&self) -> bool {
1035 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
1036 // but this should only be possible when using `-Z continue-parse-after-error` like
1037 // `compile-fail/issue-36638.rs`.
1038 self.name == keywords::SelfType.name().as_str() && self.idx == 0
1042 /// A [De Bruijn index][dbi] is a standard means of representing
1043 /// regions (and perhaps later types) in a higher-ranked setting. In
1044 /// particular, imagine a type like this:
1046 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1049 /// | +------------+ 0 | |
1051 /// +--------------------------------+ 1 |
1053 /// +------------------------------------------+ 0
1055 /// In this type, there are two binders (the outer fn and the inner
1056 /// fn). We need to be able to determine, for any given region, which
1057 /// fn type it is bound by, the inner or the outer one. There are
1058 /// various ways you can do this, but a De Bruijn index is one of the
1059 /// more convenient and has some nice properties. The basic idea is to
1060 /// count the number of binders, inside out. Some examples should help
1061 /// clarify what I mean.
1063 /// Let's start with the reference type `&'b isize` that is the first
1064 /// argument to the inner function. This region `'b` is assigned a De
1065 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1066 /// fn). The region `'a` that appears in the second argument type (`&'a
1067 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1068 /// second-innermost binder". (These indices are written on the arrays
1069 /// in the diagram).
1071 /// What is interesting is that De Bruijn index attached to a particular
1072 /// variable will vary depending on where it appears. For example,
1073 /// the final type `&'a char` also refers to the region `'a` declared on
1074 /// the outermost fn. But this time, this reference is not nested within
1075 /// any other binders (i.e., it is not an argument to the inner fn, but
1076 /// rather the outer one). Therefore, in this case, it is assigned a
1077 /// De Bruijn index of 0, because the innermost binder in that location
1078 /// is the outer fn.
1080 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1082 pub struct DebruijnIndex {
1083 DEBUG_FORMAT = "DebruijnIndex({})",
1084 const INNERMOST = 0,
1088 pub type Region<'tcx> = &'tcx RegionKind;
1090 /// Representation of regions.
1092 /// Unlike types, most region variants are "fictitious", not concrete,
1093 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1094 /// ones representing concrete regions.
1096 /// ## Bound Regions
1098 /// These are regions that are stored behind a binder and must be substituted
1099 /// with some concrete region before being used. There are 2 kind of
1100 /// bound regions: early-bound, which are bound in an item's Generics,
1101 /// and are substituted by a Substs, and late-bound, which are part of
1102 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
1103 /// the likes of `liberate_late_bound_regions`. The distinction exists
1104 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1106 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1107 /// outside their binder, e.g. in types passed to type inference, and
1108 /// should first be substituted (by placeholder regions, free regions,
1109 /// or region variables).
1111 /// ## Placeholder and Free Regions
1113 /// One often wants to work with bound regions without knowing their precise
1114 /// identity. For example, when checking a function, the lifetime of a borrow
1115 /// can end up being assigned to some region parameter. In these cases,
1116 /// it must be ensured that bounds on the region can't be accidentally
1117 /// assumed without being checked.
1119 /// To do this, we replace the bound regions with placeholder markers,
1120 /// which don't satisfy any relation not explicitly provided.
1122 /// There are 2 kinds of placeholder regions in rustc: `ReFree` and
1123 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1124 /// to be used. These also support explicit bounds: both the internally-stored
1125 /// *scope*, which the region is assumed to outlive, as well as other
1126 /// relations stored in the `FreeRegionMap`. Note that these relations
1127 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1128 /// `resolve_regions_and_report_errors`.
1130 /// When working with higher-ranked types, some region relations aren't
1131 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1132 /// `RePlaceholder` is designed for this purpose. In these contexts,
1133 /// there's also the risk that some inference variable laying around will
1134 /// get unified with your placeholder region: if you want to check whether
1135 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1136 /// with a placeholder region `'%a`, the variable `'_` would just be
1137 /// instantiated to the placeholder region `'%a`, which is wrong because
1138 /// the inference variable is supposed to satisfy the relation
1139 /// *for every value of the placeholder region*. To ensure that doesn't
1140 /// happen, you can use `leak_check`. This is more clearly explained
1141 /// by the [rustc guide].
1143 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1144 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1145 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1146 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1147 pub enum RegionKind {
1148 // Region bound in a type or fn declaration which will be
1149 // substituted 'early' -- that is, at the same time when type
1150 // parameters are substituted.
1151 ReEarlyBound(EarlyBoundRegion),
1153 // Region bound in a function scope, which will be substituted when the
1154 // function is called.
1155 ReLateBound(DebruijnIndex, BoundRegion),
1157 /// When checking a function body, the types of all arguments and so forth
1158 /// that refer to bound region parameters are modified to refer to free
1159 /// region parameters.
1162 /// A concrete region naming some statically determined scope
1163 /// (e.g. an expression or sequence of statements) within the
1164 /// current function.
1165 ReScope(region::Scope),
1167 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1170 /// A region variable. Should not exist after typeck.
1173 /// A placeholder region - basically the higher-ranked version of ReFree.
1174 /// Should not exist after typeck.
1175 RePlaceholder(ty::PlaceholderRegion),
1177 /// Empty lifetime is for data that is never accessed.
1178 /// Bottom in the region lattice. We treat ReEmpty somewhat
1179 /// specially; at least right now, we do not generate instances of
1180 /// it during the GLB computations, but rather
1181 /// generate an error instead. This is to improve error messages.
1182 /// The only way to get an instance of ReEmpty is to have a region
1183 /// variable with no constraints.
1186 /// Erased region, used by trait selection, in MIR and during codegen.
1189 /// These are regions bound in the "defining type" for a
1190 /// closure. They are used ONLY as part of the
1191 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1192 /// See `ClosureRegionRequirements` for more details.
1193 ReClosureBound(RegionVid),
1196 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1198 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1199 pub struct EarlyBoundRegion {
1202 pub name: InternedString,
1205 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1210 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1215 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1216 pub struct FloatVid {
1221 pub struct RegionVid {
1222 DEBUG_FORMAT = custom,
1226 impl Atom for RegionVid {
1227 fn index(self) -> usize {
1232 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1238 /// A `FreshTy` is one that is generated as a replacement for an
1239 /// unbound type variable. This is convenient for caching etc. See
1240 /// `infer::freshen` for more details.
1247 pub struct BoundVar { .. }
1250 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1251 pub struct BoundTy {
1253 pub kind: BoundTyKind,
1256 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1257 pub enum BoundTyKind {
1259 Param(InternedString),
1262 impl_stable_hash_for!(struct BoundTy { var, kind });
1263 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1265 impl From<BoundVar> for BoundTy {
1266 fn from(var: BoundVar) -> Self {
1269 kind: BoundTyKind::Anon,
1274 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1275 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1276 pub struct ExistentialProjection<'tcx> {
1277 pub item_def_id: DefId,
1278 pub substs: &'tcx Substs<'tcx>,
1282 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1284 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1285 /// Extracts the underlying existential trait reference from this projection.
1286 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1287 /// then this function would return a `exists T. T: Iterator` existential trait
1289 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1290 let def_id = tcx.associated_item(self.item_def_id).container.id();
1291 ty::ExistentialTraitRef{
1293 substs: self.substs,
1297 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1299 -> ty::ProjectionPredicate<'tcx>
1301 // otherwise the escaping regions would be captured by the binders
1302 debug_assert!(!self_ty.has_escaping_bound_vars());
1304 ty::ProjectionPredicate {
1305 projection_ty: ty::ProjectionTy {
1306 item_def_id: self.item_def_id,
1307 substs: tcx.mk_substs_trait(self_ty, self.substs),
1314 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1315 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1316 -> ty::PolyProjectionPredicate<'tcx> {
1317 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1320 pub fn item_def_id(&self) -> DefId {
1321 return self.skip_binder().item_def_id;
1325 impl DebruijnIndex {
1326 /// Returns the resulting index when this value is moved into
1327 /// `amount` number of new binders. So e.g. if you had
1329 /// for<'a> fn(&'a x)
1331 /// and you wanted to change to
1333 /// for<'a> fn(for<'b> fn(&'a x))
1335 /// you would need to shift the index for `'a` into 1 new binder.
1337 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1338 DebruijnIndex::from_u32(self.as_u32() + amount)
1341 /// Update this index in place by shifting it "in" through
1342 /// `amount` number of binders.
1343 pub fn shift_in(&mut self, amount: u32) {
1344 *self = self.shifted_in(amount);
1347 /// Returns the resulting index when this value is moved out from
1348 /// `amount` number of new binders.
1350 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1351 DebruijnIndex::from_u32(self.as_u32() - amount)
1354 /// Update in place by shifting out from `amount` binders.
1355 pub fn shift_out(&mut self, amount: u32) {
1356 *self = self.shifted_out(amount);
1359 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1360 /// innermost binder. That is, if we have something bound at `to_binder`,
1361 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1362 /// when moving a region out from inside binders:
1365 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1366 /// // Binder: D3 D2 D1 ^^
1369 /// Here, the region `'a` would have the debruijn index D3,
1370 /// because it is the bound 3 binders out. However, if we wanted
1371 /// to refer to that region `'a` in the second argument (the `_`),
1372 /// those two binders would not be in scope. In that case, we
1373 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1374 /// debruijn index of `'a` to D1 (the innermost binder).
1376 /// If we invoke `shift_out_to_binder` and the region is in fact
1377 /// bound by one of the binders we are shifting out of, that is an
1378 /// error (and should fail an assertion failure).
1379 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1380 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1384 impl_stable_hash_for!(struct DebruijnIndex { private });
1386 /// Region utilities
1388 /// Is this region named by the user?
1389 pub fn has_name(&self) -> bool {
1391 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1392 RegionKind::ReLateBound(_, br) => br.is_named(),
1393 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1394 RegionKind::ReScope(..) => false,
1395 RegionKind::ReStatic => true,
1396 RegionKind::ReVar(..) => false,
1397 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1398 RegionKind::ReEmpty => false,
1399 RegionKind::ReErased => false,
1400 RegionKind::ReClosureBound(..) => false,
1404 pub fn is_late_bound(&self) -> bool {
1406 ty::ReLateBound(..) => true,
1411 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1413 ty::ReLateBound(debruijn, _) => debruijn >= index,
1418 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1419 /// innermost binder. That is, if we have something bound at `to_binder`,
1420 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1421 /// when moving a region out from inside binders:
1424 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1425 /// // Binder: D3 D2 D1 ^^
1428 /// Here, the region `'a` would have the debruijn index D3,
1429 /// because it is the bound 3 binders out. However, if we wanted
1430 /// to refer to that region `'a` in the second argument (the `_`),
1431 /// those two binders would not be in scope. In that case, we
1432 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1433 /// debruijn index of `'a` to D1 (the innermost binder).
1435 /// If we invoke `shift_out_to_binder` and the region is in fact
1436 /// bound by one of the binders we are shifting out of, that is an
1437 /// error (and should fail an assertion failure).
1438 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1440 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1441 debruijn.shifted_out_to_binder(to_binder),
1448 pub fn keep_in_local_tcx(&self) -> bool {
1449 if let ty::ReVar(..) = self {
1456 pub fn type_flags(&self) -> TypeFlags {
1457 let mut flags = TypeFlags::empty();
1459 if self.keep_in_local_tcx() {
1460 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1465 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1466 flags = flags | TypeFlags::HAS_RE_INFER;
1468 ty::RePlaceholder(..) => {
1469 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1470 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1472 ty::ReLateBound(..) => {
1473 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1475 ty::ReEarlyBound(..) => {
1476 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1477 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1482 ty::ReScope { .. } => {
1483 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1487 ty::ReClosureBound(..) => {
1488 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1493 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1494 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1497 debug!("type_flags({:?}) = {:?}", self, flags);
1502 /// Given an early-bound or free region, returns the def-id where it was bound.
1503 /// For example, consider the regions in this snippet of code:
1507 /// ^^ -- early bound, declared on an impl
1509 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1510 /// ^^ ^^ ^ anonymous, late-bound
1511 /// | early-bound, appears in where-clauses
1512 /// late-bound, appears only in fn args
1517 /// Here, `free_region_binding_scope('a)` would return the def-id
1518 /// of the impl, and for all the other highlighted regions, it
1519 /// would return the def-id of the function. In other cases (not shown), this
1520 /// function might return the def-id of a closure.
1521 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1523 ty::ReEarlyBound(br) => {
1524 tcx.parent_def_id(br.def_id).unwrap()
1526 ty::ReFree(fr) => fr.scope,
1527 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1533 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1534 pub fn is_unit(&self) -> bool {
1536 Tuple(ref tys) => tys.is_empty(),
1541 pub fn is_never(&self) -> bool {
1548 pub fn is_primitive(&self) -> bool {
1550 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1556 pub fn is_ty_var(&self) -> bool {
1558 Infer(TyVar(_)) => true,
1563 pub fn is_ty_infer(&self) -> bool {
1570 pub fn is_phantom_data(&self) -> bool {
1571 if let Adt(def, _) = self.sty {
1572 def.is_phantom_data()
1578 pub fn is_bool(&self) -> bool { self.sty == Bool }
1580 pub fn is_param(&self, index: u32) -> bool {
1582 ty::Param(ref data) => data.idx == index,
1587 pub fn is_self(&self) -> bool {
1589 Param(ref p) => p.is_self(),
1594 pub fn is_slice(&self) -> bool {
1596 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1597 Slice(_) | Str => true,
1605 pub fn is_simd(&self) -> bool {
1607 Adt(def, _) => def.repr.simd(),
1612 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1614 Array(ty, _) | Slice(ty) => ty,
1615 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1616 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1620 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1622 Adt(def, substs) => {
1623 def.non_enum_variant().fields[0].ty(tcx, substs)
1625 _ => bug!("simd_type called on invalid type")
1629 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1631 Adt(def, _) => def.non_enum_variant().fields.len(),
1632 _ => bug!("simd_size called on invalid type")
1636 pub fn is_region_ptr(&self) -> bool {
1643 pub fn is_mutable_pointer(&self) -> bool {
1645 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1646 Ref(_, _, hir::Mutability::MutMutable) => true,
1651 pub fn is_unsafe_ptr(&self) -> bool {
1653 RawPtr(_) => return true,
1658 /// Returns `true` if this type is an `Arc<T>`.
1659 pub fn is_arc(&self) -> bool {
1661 Adt(def, _) => def.is_arc(),
1666 /// Returns `true` if this type is an `Rc<T>`.
1667 pub fn is_rc(&self) -> bool {
1669 Adt(def, _) => def.is_rc(),
1674 pub fn is_box(&self) -> bool {
1676 Adt(def, _) => def.is_box(),
1681 /// panics if called on any type other than `Box<T>`
1682 pub fn boxed_ty(&self) -> Ty<'tcx> {
1684 Adt(def, substs) if def.is_box() => substs.type_at(0),
1685 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1689 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1690 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1691 /// contents are abstract to rustc.)
1692 pub fn is_scalar(&self) -> bool {
1694 Bool | Char | Int(_) | Float(_) | Uint(_) |
1695 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1696 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1701 /// Returns true if this type is a floating point type and false otherwise.
1702 pub fn is_floating_point(&self) -> bool {
1705 Infer(FloatVar(_)) => true,
1710 pub fn is_trait(&self) -> bool {
1712 Dynamic(..) => true,
1717 pub fn is_enum(&self) -> bool {
1719 Adt(adt_def, _) => {
1726 pub fn is_closure(&self) -> bool {
1728 Closure(..) => true,
1733 pub fn is_generator(&self) -> bool {
1735 Generator(..) => true,
1741 pub fn is_integral(&self) -> bool {
1743 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1748 pub fn is_fresh_ty(&self) -> bool {
1750 Infer(FreshTy(_)) => true,
1755 pub fn is_fresh(&self) -> bool {
1757 Infer(FreshTy(_)) => true,
1758 Infer(FreshIntTy(_)) => true,
1759 Infer(FreshFloatTy(_)) => true,
1764 pub fn is_char(&self) -> bool {
1772 pub fn is_fp(&self) -> bool {
1774 Infer(FloatVar(_)) | Float(_) => true,
1779 pub fn is_numeric(&self) -> bool {
1780 self.is_integral() || self.is_fp()
1783 pub fn is_signed(&self) -> bool {
1790 pub fn is_machine(&self) -> bool {
1792 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1793 Int(..) | Uint(..) | Float(..) => true,
1798 pub fn has_concrete_skeleton(&self) -> bool {
1800 Param(_) | Infer(_) | Error => false,
1805 /// Returns the type and mutability of *ty.
1807 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1808 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1809 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1811 Adt(def, _) if def.is_box() => {
1813 ty: self.boxed_ty(),
1814 mutbl: hir::MutImmutable,
1817 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1818 RawPtr(mt) if explicit => Some(mt),
1823 /// Returns the type of `ty[i]`.
1824 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1826 Array(ty, _) | Slice(ty) => Some(ty),
1831 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1833 FnDef(def_id, substs) => {
1834 tcx.fn_sig(def_id).subst(tcx, substs)
1837 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1841 pub fn is_fn(&self) -> bool {
1843 FnDef(..) | FnPtr(_) => true,
1848 pub fn is_impl_trait(&self) -> bool {
1856 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1858 Adt(adt, _) => Some(adt),
1863 /// Push onto `out` the regions directly referenced from this type (but not
1864 /// types reachable from this type via `walk_tys`). This ignores late-bound
1865 /// regions binders.
1866 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
1868 Ref(region, _, _) => {
1871 Dynamic(ref obj, region) => {
1873 out.extend(obj.principal().skip_binder().substs.regions());
1875 Adt(_, substs) | Opaque(_, substs) => {
1876 out.extend(substs.regions())
1878 Closure(_, ClosureSubsts { ref substs }) |
1879 Generator(_, GeneratorSubsts { ref substs }, _) => {
1880 out.extend(substs.regions())
1882 Projection(ref data) | UnnormalizedProjection(ref data) => {
1883 out.extend(data.substs.regions())
1887 GeneratorWitness(..) |
1908 /// When we create a closure, we record its kind (i.e., what trait
1909 /// it implements) into its `ClosureSubsts` using a type
1910 /// parameter. This is kind of a phantom type, except that the
1911 /// most convenient thing for us to are the integral types. This
1912 /// function converts such a special type into the closure
1913 /// kind. To go the other way, use
1914 /// `tcx.closure_kind_ty(closure_kind)`.
1916 /// Note that during type checking, we use an inference variable
1917 /// to represent the closure kind, because it has not yet been
1918 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1919 /// is complete, that type variable will be unified.
1920 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1922 Int(int_ty) => match int_ty {
1923 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1924 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1925 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1926 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1931 Error => Some(ty::ClosureKind::Fn),
1933 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1937 /// Fast path helper for testing if a type is `Sized`.
1939 /// Returning true means the type is known to be sized. Returning
1940 /// `false` means nothing -- could be sized, might not be.
1941 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1943 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1944 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1945 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1946 ty::Char | ty::Ref(..) | ty::Generator(..) |
1947 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1948 ty::Never | ty::Error =>
1951 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
1955 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
1957 ty::Adt(def, _substs) =>
1958 def.sized_constraint(tcx).is_empty(),
1960 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
1962 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
1964 ty::Infer(ty::TyVar(_)) => false,
1967 ty::Placeholder(..) |
1968 ty::Infer(ty::FreshTy(_)) |
1969 ty::Infer(ty::FreshIntTy(_)) |
1970 ty::Infer(ty::FreshFloatTy(_)) =>
1971 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
1976 /// Typed constant value.
1977 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
1978 pub struct Const<'tcx> {
1981 pub val: ConstValue<'tcx>,
1984 impl<'tcx> Const<'tcx> {
1986 tcx: TyCtxt<'_, '_, 'tcx>,
1988 substs: &'tcx Substs<'tcx>,
1991 tcx.mk_const(Const {
1992 val: ConstValue::Unevaluated(def_id, substs),
1998 pub fn from_const_value(
1999 tcx: TyCtxt<'_, '_, 'tcx>,
2000 val: ConstValue<'tcx>,
2003 tcx.mk_const(Const {
2011 tcx: TyCtxt<'_, '_, 'tcx>,
2015 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
2020 tcx: TyCtxt<'_, '_, 'tcx>,
2022 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2024 let ty = tcx.lift_to_global(&ty).unwrap();
2025 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2026 panic!("could not compute layout for {:?}: {:?}", ty, e)
2028 let shift = 128 - size.bits();
2029 let truncated = (bits << shift) >> shift;
2030 assert_eq!(truncated, bits, "from_bits called with untruncated value");
2031 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
2035 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2036 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
2040 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
2041 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2045 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
2046 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2052 tcx: TyCtxt<'_, '_, 'tcx>,
2053 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2055 if self.ty != ty.value {
2058 let ty = tcx.lift_to_global(&ty).unwrap();
2059 let size = tcx.layout_of(ty).ok()?.size;
2060 self.val.try_to_bits(size)
2064 pub fn to_ptr(&self) -> Option<Pointer> {
2065 self.val.try_to_ptr()
2071 tcx: TyCtxt<'_, '_, '_>,
2072 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2074 assert_eq!(self.ty, ty.value);
2075 let ty = tcx.lift_to_global(&ty).unwrap();
2076 let size = tcx.layout_of(ty).ok()?.size;
2077 self.val.try_to_bits(size)
2081 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2082 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2090 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2091 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2097 tcx: TyCtxt<'_, '_, '_>,
2098 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2100 self.assert_bits(tcx, ty).unwrap_or_else(||
2101 bug!("expected bits of {}, got {:#?}", ty.value, self))
2105 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2106 self.assert_usize(tcx).unwrap_or_else(||
2107 bug!("expected constant usize, got {:#?}", self))
2111 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}