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};
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, which is output (for a function
130 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
132 /// For example the type of `bar` here:
135 /// fn foo() -> i32 { 1 }
136 /// let bar = foo; // bar: fn() -> i32 {foo}
138 FnDef(DefId, &'tcx Substs<'tcx>),
140 /// A pointer to a function. Written as `fn() -> i32`.
142 /// For example the type of `bar` here:
145 /// fn foo() -> i32 { 1 }
146 /// let bar: fn() -> i32 = foo;
148 FnPtr(PolyFnSig<'tcx>),
150 /// A trait, defined with `trait`.
151 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
153 /// The anonymous type of a closure. Used to represent the type of
155 Closure(DefId, ClosureSubsts<'tcx>),
157 /// The anonymous type of a generator. Used to represent the type of
159 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
161 /// A type representin the types stored inside a generator.
162 /// This should only appear in GeneratorInteriors.
163 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
165 /// The never type `!`
168 /// A tuple type. For example, `(i32, bool)`.
169 Tuple(&'tcx List<Ty<'tcx>>),
171 /// The projection of an associated type. For example,
172 /// `<T as Trait<..>>::N`.
173 Projection(ProjectionTy<'tcx>),
175 /// A placeholder type used when we do not have enough information
176 /// to normalize the projection of an associated type to an
177 /// existing concrete type. Currently only used with chalk-engine.
178 UnnormalizedProjection(ProjectionTy<'tcx>),
180 /// Opaque (`impl Trait`) type found in a return type.
181 /// The `DefId` comes either from
182 /// * the `impl Trait` ast::Ty node,
183 /// * or the `existential type` declaration
184 /// The substitutions are for the generics of the function in question.
185 /// After typeck, the concrete type can be found in the `types` map.
186 Opaque(DefId, &'tcx Substs<'tcx>),
188 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
191 /// Bound type variable, used only when preparing a trait query.
194 /// A type variable used during type checking.
197 /// A placeholder for a type which could not be computed; this is
198 /// propagated to avoid useless error messages.
202 /// A closure can be modeled as a struct that looks like:
204 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
212 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
213 /// in scope on the function that defined the closure,
214 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
215 /// is rather hackily encoded via a scalar type. See
216 /// `TyS::to_opt_closure_kind` for details.
217 /// - CS represents the *closure signature*, representing as a `fn()`
218 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
219 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
221 /// - U0...Uk are type parameters representing the types of its upvars
222 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
223 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
225 /// So, for example, given this function:
227 /// fn foo<'a, T>(data: &'a mut T) {
228 /// do(|| data.count += 1)
231 /// the type of the closure would be something like:
233 /// struct Closure<'a, T, U0> {
237 /// Note that the type of the upvar is not specified in the struct.
238 /// You may wonder how the impl would then be able to use the upvar,
239 /// if it doesn't know it's type? The answer is that the impl is
240 /// (conceptually) not fully generic over Closure but rather tied to
241 /// instances with the expected upvar types:
243 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
247 /// You can see that the *impl* fully specified the type of the upvar
248 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
249 /// (Here, I am assuming that `data` is mut-borrowed.)
251 /// Now, the last question you may ask is: Why include the upvar types
252 /// as extra type parameters? The reason for this design is that the
253 /// upvar types can reference lifetimes that are internal to the
254 /// creating function. In my example above, for example, the lifetime
255 /// `'b` represents the scope of the closure itself; this is some
256 /// subset of `foo`, probably just the scope of the call to the to
257 /// `do()`. If we just had the lifetime/type parameters from the
258 /// enclosing function, we couldn't name this lifetime `'b`. Note that
259 /// there can also be lifetimes in the types of the upvars themselves,
260 /// if one of them happens to be a reference to something that the
261 /// creating fn owns.
263 /// OK, you say, so why not create a more minimal set of parameters
264 /// that just includes the extra lifetime parameters? The answer is
265 /// primarily that it would be hard --- we don't know at the time when
266 /// we create the closure type what the full types of the upvars are,
267 /// nor do we know which are borrowed and which are not. In this
268 /// design, we can just supply a fresh type parameter and figure that
271 /// All right, you say, but why include the type parameters from the
272 /// original function then? The answer is that codegen may need them
273 /// when monomorphizing, and they may not appear in the upvars. A
274 /// closure could capture no variables but still make use of some
275 /// in-scope type parameter with a bound (e.g., if our example above
276 /// had an extra `U: Default`, and the closure called `U::default()`).
278 /// There is another reason. This design (implicitly) prohibits
279 /// closures from capturing themselves (except via a trait
280 /// object). This simplifies closure inference considerably, since it
281 /// means that when we infer the kind of a closure or its upvars, we
282 /// don't have to handle cycles where the decisions we make for
283 /// closure C wind up influencing the decisions we ought to make for
284 /// closure C (which would then require fixed point iteration to
285 /// handle). Plus it fixes an ICE. :P
289 /// Perhaps surprisingly, `ClosureSubsts` are also used for
290 /// generators. In that case, what is written above is only half-true
291 /// -- the set of type parameters is similar, but the role of CK and
292 /// CS are different. CK represents the "yield type" and CS
293 /// represents the "return type" of the generator.
295 /// It'd be nice to split this struct into ClosureSubsts and
296 /// GeneratorSubsts, I believe. -nmatsakis
297 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
298 pub struct ClosureSubsts<'tcx> {
299 /// Lifetime and type parameters from the enclosing function,
300 /// concatenated with the types of the upvars.
302 /// These are separated out because codegen wants to pass them around
303 /// when monomorphizing.
304 pub substs: &'tcx Substs<'tcx>,
307 /// Struct returned by `split()`. Note that these are subslices of the
308 /// parent slice and not canonical substs themselves.
309 struct SplitClosureSubsts<'tcx> {
310 closure_kind_ty: Ty<'tcx>,
311 closure_sig_ty: Ty<'tcx>,
312 upvar_kinds: &'tcx [Kind<'tcx>],
315 impl<'tcx> ClosureSubsts<'tcx> {
316 /// Divides the closure substs into their respective
317 /// components. Single source of truth with respect to the
319 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
320 let generics = tcx.generics_of(def_id);
321 let parent_len = generics.parent_count;
323 closure_kind_ty: self.substs.type_at(parent_len),
324 closure_sig_ty: self.substs.type_at(parent_len + 1),
325 upvar_kinds: &self.substs[parent_len + 2..],
330 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
331 impl Iterator<Item=Ty<'tcx>> + 'tcx
333 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
334 upvar_kinds.iter().map(|t| {
335 if let UnpackedKind::Type(ty) = t.unpack() {
338 bug!("upvar should be type")
343 /// Returns the closure kind for this closure; may return a type
344 /// variable during inference. To get the closure kind during
345 /// inference, use `infcx.closure_kind(def_id, substs)`.
346 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
347 self.split(def_id, tcx).closure_kind_ty
350 /// Returns the type representing the closure signature for this
351 /// closure; may contain type variables during inference. To get
352 /// the closure signature during inference, use
353 /// `infcx.fn_sig(def_id)`.
354 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
355 self.split(def_id, tcx).closure_sig_ty
358 /// Returns the closure kind for this closure; only usable outside
359 /// of an inference context, because in that context we know that
360 /// there are no type variables.
362 /// If you have an inference context, use `infcx.closure_kind()`.
363 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
364 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
367 /// Extracts the signature from the closure; only usable outside
368 /// of an inference context, because in that context we know that
369 /// there are no type variables.
371 /// If you have an inference context, use `infcx.closure_sig()`.
372 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
373 match self.closure_sig_ty(def_id, tcx).sty {
374 ty::FnPtr(sig) => sig,
375 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
380 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
381 pub struct GeneratorSubsts<'tcx> {
382 pub substs: &'tcx Substs<'tcx>,
385 struct SplitGeneratorSubsts<'tcx> {
389 upvar_kinds: &'tcx [Kind<'tcx>],
392 impl<'tcx> GeneratorSubsts<'tcx> {
393 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
394 let generics = tcx.generics_of(def_id);
395 let parent_len = generics.parent_count;
396 SplitGeneratorSubsts {
397 yield_ty: self.substs.type_at(parent_len),
398 return_ty: self.substs.type_at(parent_len + 1),
399 witness: self.substs.type_at(parent_len + 2),
400 upvar_kinds: &self.substs[parent_len + 3..],
404 /// This describes the types that can be contained in a generator.
405 /// It will be a type variable initially and unified in the last stages of typeck of a body.
406 /// It contains a tuple of all the types that could end up on a generator frame.
407 /// The state transformation MIR pass may only produce layouts which mention types
408 /// in this tuple. Upvars are not counted here.
409 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
410 self.split(def_id, tcx).witness
414 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
415 impl Iterator<Item=Ty<'tcx>> + 'tcx
417 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
418 upvar_kinds.iter().map(|t| {
419 if let UnpackedKind::Type(ty) = t.unpack() {
422 bug!("upvar should be type")
427 /// Returns the type representing the yield type of the generator.
428 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
429 self.split(def_id, tcx).yield_ty
432 /// Returns the type representing the return type of the generator.
433 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
434 self.split(def_id, tcx).return_ty
437 /// Return the "generator signature", which consists of its yield
438 /// and return types.
440 /// NB. Some bits of the code prefers to see this wrapped in a
441 /// binder, but it never contains bound regions. Probably this
442 /// function should be removed.
443 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
444 ty::Binder::dummy(self.sig(def_id, tcx))
447 /// Return the "generator signature", which consists of its yield
448 /// and return types.
449 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
451 yield_ty: self.yield_ty(def_id, tcx),
452 return_ty: self.return_ty(def_id, tcx),
457 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
458 /// This returns the types of the MIR locals which had to be stored across suspension points.
459 /// It is calculated in rustc_mir::transform::generator::StateTransform.
460 /// All the types here must be in the tuple in GeneratorInterior.
464 tcx: TyCtxt<'a, 'gcx, 'tcx>,
465 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
466 let state = tcx.generator_layout(def_id).fields.iter();
467 state.map(move |d| d.ty.subst(tcx, self.substs))
470 /// This is the types of the fields of a generate which
471 /// is available before the generator transformation.
472 /// It includes the upvars and the state discriminant which is u32.
473 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
474 impl Iterator<Item=Ty<'tcx>> + 'a
476 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
479 /// This is the types of all the fields stored in a generator.
480 /// It includes the upvars, state types and the state discriminant which is u32.
481 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
482 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
484 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
488 #[derive(Debug, Copy, Clone)]
489 pub enum UpvarSubsts<'tcx> {
490 Closure(ClosureSubsts<'tcx>),
491 Generator(GeneratorSubsts<'tcx>),
494 impl<'tcx> UpvarSubsts<'tcx> {
496 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
497 impl Iterator<Item=Ty<'tcx>> + 'tcx
499 let upvar_kinds = match self {
500 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
501 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
503 upvar_kinds.iter().map(|t| {
504 if let UnpackedKind::Type(ty) = t.unpack() {
507 bug!("upvar should be type")
513 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
514 pub enum ExistentialPredicate<'tcx> {
516 Trait(ExistentialTraitRef<'tcx>),
517 /// e.g. Iterator::Item = T
518 Projection(ExistentialProjection<'tcx>),
523 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
524 /// Compares via an ordering that will not change if modules are reordered or other changes are
525 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
526 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
527 use self::ExistentialPredicate::*;
528 match (*self, *other) {
529 (Trait(_), Trait(_)) => Ordering::Equal,
530 (Projection(ref a), Projection(ref b)) =>
531 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
532 (AutoTrait(ref a), AutoTrait(ref b)) =>
533 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
534 (Trait(_), _) => Ordering::Less,
535 (Projection(_), Trait(_)) => Ordering::Greater,
536 (Projection(_), _) => Ordering::Less,
537 (AutoTrait(_), _) => Ordering::Greater,
543 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
544 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
545 -> ty::Predicate<'tcx> {
547 match *self.skip_binder() {
548 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
549 ExistentialPredicate::Projection(p) =>
550 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
551 ExistentialPredicate::AutoTrait(did) => {
552 let trait_ref = Binder(ty::TraitRef {
554 substs: tcx.mk_substs_trait(self_ty, &[]),
556 trait_ref.to_predicate()
562 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
564 impl<'tcx> List<ExistentialPredicate<'tcx>> {
565 pub fn principal(&self) -> ExistentialTraitRef<'tcx> {
567 ExistentialPredicate::Trait(tr) => tr,
568 other => bug!("first predicate is {:?}", other),
573 pub fn projection_bounds<'a>(&'a self) ->
574 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
575 self.iter().filter_map(|predicate| {
577 ExistentialPredicate::Projection(p) => Some(p),
584 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
585 self.iter().filter_map(|predicate| {
587 ExistentialPredicate::AutoTrait(d) => Some(d),
594 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
595 pub fn principal(&self) -> PolyExistentialTraitRef<'tcx> {
596 Binder::bind(self.skip_binder().principal())
600 pub fn projection_bounds<'a>(&'a self) ->
601 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
602 self.skip_binder().projection_bounds().map(Binder::bind)
606 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
607 self.skip_binder().auto_traits()
610 pub fn iter<'a>(&'a self)
611 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
612 self.skip_binder().iter().cloned().map(Binder::bind)
616 /// A complete reference to a trait. These take numerous guises in syntax,
617 /// but perhaps the most recognizable form is in a where clause:
621 /// This would be represented by a trait-reference where the def-id is the
622 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
623 /// and `U` as parameter 1.
625 /// Trait references also appear in object types like `Foo<U>`, but in
626 /// that case the `Self` parameter is absent from the substitutions.
628 /// Note that a `TraitRef` introduces a level of region binding, to
629 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
630 /// U>` or higher-ranked object types.
631 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
632 pub struct TraitRef<'tcx> {
634 pub substs: &'tcx Substs<'tcx>,
637 impl<'tcx> TraitRef<'tcx> {
638 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
639 TraitRef { def_id: def_id, substs: substs }
642 /// Returns a TraitRef of the form `P0: Foo<P1..Pn>` where `Pi`
643 /// are the parameters defined on trait.
644 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
647 substs: Substs::identity_for_item(tcx, def_id),
651 pub fn self_ty(&self) -> Ty<'tcx> {
652 self.substs.type_at(0)
655 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
656 // Select only the "input types" from a trait-reference. For
657 // now this is all the types that appear in the
658 // trait-reference, but it should eventually exclude
663 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
665 substs: &Substs<'tcx>)
666 -> ty::TraitRef<'tcx> {
667 let defs = tcx.generics_of(trait_id);
671 substs: tcx.intern_substs(&substs[..defs.params.len()])
676 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
678 impl<'tcx> PolyTraitRef<'tcx> {
679 pub fn self_ty(&self) -> Ty<'tcx> {
680 self.skip_binder().self_ty()
683 pub fn def_id(&self) -> DefId {
684 self.skip_binder().def_id
687 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
688 // Note that we preserve binding levels
689 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
693 /// An existential reference to a trait, where `Self` is erased.
694 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
696 /// exists T. T: Trait<'a, 'b, X, Y>
698 /// The substitutions don't include the erased `Self`, only trait
699 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
700 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
701 pub struct ExistentialTraitRef<'tcx> {
703 pub substs: &'tcx Substs<'tcx>,
706 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
707 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
708 // Select only the "input types" from a trait-reference. For
709 // now this is all the types that appear in the
710 // trait-reference, but it should eventually exclude
715 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
716 trait_ref: ty::TraitRef<'tcx>)
717 -> ty::ExistentialTraitRef<'tcx> {
718 // Assert there is a Self.
719 trait_ref.substs.type_at(0);
721 ty::ExistentialTraitRef {
722 def_id: trait_ref.def_id,
723 substs: tcx.intern_substs(&trait_ref.substs[1..])
727 /// Object types don't have a self-type specified. Therefore, when
728 /// we convert the principal trait-ref into a normal trait-ref,
729 /// you must give *some* self-type. A common choice is `mk_err()`
730 /// or some placeholder type.
731 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
732 -> ty::TraitRef<'tcx> {
733 // otherwise the escaping regions would be captured by the binder
734 // debug_assert!(!self_ty.has_escaping_regions());
738 substs: tcx.mk_substs_trait(self_ty, self.substs)
743 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
745 impl<'tcx> PolyExistentialTraitRef<'tcx> {
746 pub fn def_id(&self) -> DefId {
747 self.skip_binder().def_id
750 /// Object types don't have a self-type specified. Therefore, when
751 /// we convert the principal trait-ref into a normal trait-ref,
752 /// you must give *some* self-type. A common choice is `mk_err()`
753 /// or some placeholder type.
754 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
756 -> ty::PolyTraitRef<'tcx> {
757 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
761 /// Binder is a binder for higher-ranked lifetimes. It is part of the
762 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
763 /// (which would be represented by the type `PolyTraitRef ==
764 /// Binder<TraitRef>`). Note that when we instantiate,
765 /// erase, or otherwise "discharge" these bound regions, we change the
766 /// type from `Binder<T>` to just `T` (see
767 /// e.g. `liberate_late_bound_regions`).
768 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
769 pub struct Binder<T>(T);
772 /// Wraps `value` in a binder, asserting that `value` does not
773 /// contain any bound regions that would be bound by the
774 /// binder. This is commonly used to 'inject' a value T into a
775 /// different binding level.
776 pub fn dummy<'tcx>(value: T) -> Binder<T>
777 where T: TypeFoldable<'tcx>
779 debug_assert!(!value.has_escaping_regions());
783 /// Wraps `value` in a binder, binding late-bound regions (if any).
784 pub fn bind<'tcx>(value: T) -> Binder<T>
789 /// Skips the binder and returns the "bound" value. This is a
790 /// risky thing to do because it's easy to get confused about
791 /// debruijn indices and the like. It is usually better to
792 /// discharge the binder using `no_late_bound_regions` or
793 /// `replace_late_bound_regions` or something like
794 /// that. `skip_binder` is only valid when you are either
795 /// extracting data that has nothing to do with bound regions, you
796 /// are doing some sort of test that does not involve bound
797 /// regions, or you are being very careful about your depth
800 /// Some examples where `skip_binder` is reasonable:
802 /// - extracting the def-id from a PolyTraitRef;
803 /// - comparing the self type of a PolyTraitRef to see if it is equal to
804 /// a type parameter `X`, since the type `X` does not reference any regions
805 pub fn skip_binder(&self) -> &T {
809 pub fn as_ref(&self) -> Binder<&T> {
813 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
814 where F: FnOnce(&T) -> U
816 self.as_ref().map_bound(f)
819 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
820 where F: FnOnce(T) -> U
825 /// Unwraps and returns the value within, but only if it contains
826 /// no bound regions at all. (In other words, if this binder --
827 /// and indeed any enclosing binder -- doesn't bind anything at
828 /// all.) Otherwise, returns `None`.
830 /// (One could imagine having a method that just unwraps a single
831 /// binder, but permits late-bound regions bound by enclosing
832 /// binders, but that would require adjusting the debruijn
833 /// indices, and given the shallow binding structure we often use,
834 /// would not be that useful.)
835 pub fn no_late_bound_regions<'tcx>(self) -> Option<T>
836 where T : TypeFoldable<'tcx>
838 if self.skip_binder().has_escaping_regions() {
841 Some(self.skip_binder().clone())
845 /// Given two things that have the same binder level,
846 /// and an operation that wraps on their contents, execute the operation
847 /// and then wrap its result.
849 /// `f` should consider bound regions at depth 1 to be free, and
850 /// anything it produces with bound regions at depth 1 will be
851 /// bound in the resulting return value.
852 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
853 where F: FnOnce(T, U) -> R
855 Binder(f(self.0, u.0))
858 /// Split the contents into two things that share the same binder
859 /// level as the original, returning two distinct binders.
861 /// `f` should consider bound regions at depth 1 to be free, and
862 /// anything it produces with bound regions at depth 1 will be
863 /// bound in the resulting return values.
864 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
865 where F: FnOnce(T) -> (U, V)
867 let (u, v) = f(self.0);
868 (Binder(u), Binder(v))
872 /// Represents the projection of an associated type. In explicit UFCS
873 /// form this would be written `<T as Trait<..>>::N`.
874 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
875 pub struct ProjectionTy<'tcx> {
876 /// The parameters of the associated item.
877 pub substs: &'tcx Substs<'tcx>,
879 /// The DefId of the TraitItem for the associated type N.
881 /// Note that this is not the DefId of the TraitRef containing this
882 /// associated type, which is in tcx.associated_item(item_def_id).container.
883 pub item_def_id: DefId,
886 impl<'a, 'tcx> ProjectionTy<'tcx> {
887 /// Construct a ProjectionTy by searching the trait from trait_ref for the
888 /// associated item named item_name.
889 pub fn from_ref_and_name(
890 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
891 ) -> ProjectionTy<'tcx> {
892 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
893 item.kind == ty::AssociatedKind::Type &&
894 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
898 substs: trait_ref.substs,
903 /// Extracts the underlying trait reference from this projection.
904 /// For example, if this is a projection of `<T as Iterator>::Item`,
905 /// then this function would return a `T: Iterator` trait reference.
906 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
907 let def_id = tcx.associated_item(self.item_def_id).container.id();
914 pub fn self_ty(&self) -> Ty<'tcx> {
915 self.substs.type_at(0)
919 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
920 pub struct GenSig<'tcx> {
921 pub yield_ty: Ty<'tcx>,
922 pub return_ty: Ty<'tcx>,
925 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
927 impl<'tcx> PolyGenSig<'tcx> {
928 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
929 self.map_bound_ref(|sig| sig.yield_ty)
931 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
932 self.map_bound_ref(|sig| sig.return_ty)
936 /// Signature of a function type, which I have arbitrarily
937 /// decided to use to refer to the input/output types.
939 /// - `inputs` is the list of arguments and their modes.
940 /// - `output` is the return type.
941 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
942 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
943 pub struct FnSig<'tcx> {
944 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
946 pub unsafety: hir::Unsafety,
950 impl<'tcx> FnSig<'tcx> {
951 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
952 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
955 pub fn output(&self) -> Ty<'tcx> {
956 self.inputs_and_output[self.inputs_and_output.len() - 1]
960 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
962 impl<'tcx> PolyFnSig<'tcx> {
963 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
964 self.map_bound_ref(|fn_sig| fn_sig.inputs())
966 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
967 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
969 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
970 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
972 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
973 self.map_bound_ref(|fn_sig| fn_sig.output())
975 pub fn variadic(&self) -> bool {
976 self.skip_binder().variadic
978 pub fn unsafety(&self) -> hir::Unsafety {
979 self.skip_binder().unsafety
981 pub fn abi(&self) -> abi::Abi {
982 self.skip_binder().abi
986 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
989 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
992 pub name: InternedString,
995 impl<'a, 'gcx, 'tcx> ParamTy {
996 pub fn new(index: u32, name: InternedString) -> ParamTy {
997 ParamTy { idx: index, name: name }
1000 pub fn for_self() -> ParamTy {
1001 ParamTy::new(0, keywords::SelfType.name().as_interned_str())
1004 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1005 ParamTy::new(def.index, def.name)
1008 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1009 tcx.mk_ty_param(self.idx, self.name)
1012 pub fn is_self(&self) -> bool {
1013 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
1014 // but this should only be possible when using `-Z continue-parse-after-error` like
1015 // `compile-fail/issue-36638.rs`.
1016 self.name == keywords::SelfType.name().as_str() && self.idx == 0
1020 /// A [De Bruijn index][dbi] is a standard means of representing
1021 /// regions (and perhaps later types) in a higher-ranked setting. In
1022 /// particular, imagine a type like this:
1024 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1027 /// | +------------+ 0 | |
1029 /// +--------------------------------+ 1 |
1031 /// +------------------------------------------+ 0
1033 /// In this type, there are two binders (the outer fn and the inner
1034 /// fn). We need to be able to determine, for any given region, which
1035 /// fn type it is bound by, the inner or the outer one. There are
1036 /// various ways you can do this, but a De Bruijn index is one of the
1037 /// more convenient and has some nice properties. The basic idea is to
1038 /// count the number of binders, inside out. Some examples should help
1039 /// clarify what I mean.
1041 /// Let's start with the reference type `&'b isize` that is the first
1042 /// argument to the inner function. This region `'b` is assigned a De
1043 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1044 /// fn). The region `'a` that appears in the second argument type (`&'a
1045 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1046 /// second-innermost binder". (These indices are written on the arrays
1047 /// in the diagram).
1049 /// What is interesting is that De Bruijn index attached to a particular
1050 /// variable will vary depending on where it appears. For example,
1051 /// the final type `&'a char` also refers to the region `'a` declared on
1052 /// the outermost fn. But this time, this reference is not nested within
1053 /// any other binders (i.e., it is not an argument to the inner fn, but
1054 /// rather the outer one). Therefore, in this case, it is assigned a
1055 /// De Bruijn index of 0, because the innermost binder in that location
1056 /// is the outer fn.
1058 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1060 pub struct DebruijnIndex {
1061 DEBUG_FORMAT = "DebruijnIndex({})",
1062 const INNERMOST = 0,
1066 pub type Region<'tcx> = &'tcx RegionKind;
1068 /// Representation of regions.
1070 /// Unlike types, most region variants are "fictitious", not concrete,
1071 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1072 /// ones representing concrete regions.
1074 /// ## Bound Regions
1076 /// These are regions that are stored behind a binder and must be substituted
1077 /// with some concrete region before being used. There are 2 kind of
1078 /// bound regions: early-bound, which are bound in an item's Generics,
1079 /// and are substituted by a Substs, and late-bound, which are part of
1080 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
1081 /// the likes of `liberate_late_bound_regions`. The distinction exists
1082 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1084 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1085 /// outside their binder, e.g. in types passed to type inference, and
1086 /// should first be substituted (by placeholder regions, free regions,
1087 /// or region variables).
1089 /// ## Placeholder and Free Regions
1091 /// One often wants to work with bound regions without knowing their precise
1092 /// identity. For example, when checking a function, the lifetime of a borrow
1093 /// can end up being assigned to some region parameter. In these cases,
1094 /// it must be ensured that bounds on the region can't be accidentally
1095 /// assumed without being checked.
1097 /// To do this, we replace the bound regions with placeholder markers,
1098 /// which don't satisfy any relation not explicitly provided.
1100 /// There are 2 kinds of placeholder regions in rustc: `ReFree` and
1101 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1102 /// to be used. These also support explicit bounds: both the internally-stored
1103 /// *scope*, which the region is assumed to outlive, as well as other
1104 /// relations stored in the `FreeRegionMap`. Note that these relations
1105 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1106 /// `resolve_regions_and_report_errors`.
1108 /// When working with higher-ranked types, some region relations aren't
1109 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1110 /// `RePlaceholder` is designed for this purpose. In these contexts,
1111 /// there's also the risk that some inference variable laying around will
1112 /// get unified with your placeholder region: if you want to check whether
1113 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1114 /// with a placeholder region `'%a`, the variable `'_` would just be
1115 /// instantiated to the placeholder region `'%a`, which is wrong because
1116 /// the inference variable is supposed to satisfy the relation
1117 /// *for every value of the placeholder region*. To ensure that doesn't
1118 /// happen, you can use `leak_check`. This is more clearly explained
1119 /// by the [rustc guide].
1121 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1122 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1123 /// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/traits/hrtb.html
1124 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1125 pub enum RegionKind {
1126 // Region bound in a type or fn declaration which will be
1127 // substituted 'early' -- that is, at the same time when type
1128 // parameters are substituted.
1129 ReEarlyBound(EarlyBoundRegion),
1131 // Region bound in a function scope, which will be substituted when the
1132 // function is called.
1133 ReLateBound(DebruijnIndex, BoundRegion),
1135 /// When checking a function body, the types of all arguments and so forth
1136 /// that refer to bound region parameters are modified to refer to free
1137 /// region parameters.
1140 /// A concrete region naming some statically determined scope
1141 /// (e.g. an expression or sequence of statements) within the
1142 /// current function.
1143 ReScope(region::Scope),
1145 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1148 /// A region variable. Should not exist after typeck.
1151 /// A placeholder region - basically the higher-ranked version of ReFree.
1152 /// Should not exist after typeck.
1153 RePlaceholder(ty::Placeholder),
1155 /// Empty lifetime is for data that is never accessed.
1156 /// Bottom in the region lattice. We treat ReEmpty somewhat
1157 /// specially; at least right now, we do not generate instances of
1158 /// it during the GLB computations, but rather
1159 /// generate an error instead. This is to improve error messages.
1160 /// The only way to get an instance of ReEmpty is to have a region
1161 /// variable with no constraints.
1164 /// Erased region, used by trait selection, in MIR and during codegen.
1167 /// These are regions bound in the "defining type" for a
1168 /// closure. They are used ONLY as part of the
1169 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1170 /// See `ClosureRegionRequirements` for more details.
1171 ReClosureBound(RegionVid),
1173 /// Canonicalized region, used only when preparing a trait query.
1174 ReCanonical(BoundTyIndex),
1177 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1179 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1180 pub struct EarlyBoundRegion {
1183 pub name: InternedString,
1186 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1191 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1196 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1197 pub struct FloatVid {
1202 pub struct RegionVid {
1203 DEBUG_FORMAT = custom,
1207 impl Atom for RegionVid {
1208 fn index(self) -> usize {
1213 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1219 /// A `FreshTy` is one that is generated as a replacement for an
1220 /// unbound type variable. This is convenient for caching etc. See
1221 /// `infer::freshen` for more details.
1228 pub struct BoundTyIndex { .. }
1231 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1232 pub struct BoundTy {
1233 pub level: DebruijnIndex,
1234 pub var: BoundTyIndex,
1235 pub kind: BoundTyKind,
1238 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1239 pub enum BoundTyKind {
1241 Param(InternedString),
1244 impl_stable_hash_for!(struct BoundTy { level, var, kind });
1245 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1248 pub fn new(level: DebruijnIndex, var: BoundTyIndex) -> Self {
1249 debug_assert_eq!(ty::INNERMOST, level);
1253 kind: BoundTyKind::Anon,
1258 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1259 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1260 pub struct ExistentialProjection<'tcx> {
1261 pub item_def_id: DefId,
1262 pub substs: &'tcx Substs<'tcx>,
1266 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1268 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1269 /// Extracts the underlying existential trait reference from this projection.
1270 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1271 /// then this function would return a `exists T. T: Iterator` existential trait
1273 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1274 let def_id = tcx.associated_item(self.item_def_id).container.id();
1275 ty::ExistentialTraitRef{
1277 substs: self.substs,
1281 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1283 -> ty::ProjectionPredicate<'tcx>
1285 // otherwise the escaping regions would be captured by the binders
1286 debug_assert!(!self_ty.has_escaping_regions());
1288 ty::ProjectionPredicate {
1289 projection_ty: ty::ProjectionTy {
1290 item_def_id: self.item_def_id,
1291 substs: tcx.mk_substs_trait(self_ty, self.substs),
1298 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1299 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1300 -> ty::PolyProjectionPredicate<'tcx> {
1301 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1304 pub fn item_def_id(&self) -> DefId {
1305 return self.skip_binder().item_def_id;
1309 impl DebruijnIndex {
1310 /// Returns the resulting index when this value is moved into
1311 /// `amount` number of new binders. So e.g. if you had
1313 /// for<'a> fn(&'a x)
1315 /// and you wanted to change to
1317 /// for<'a> fn(for<'b> fn(&'a x))
1319 /// you would need to shift the index for `'a` into 1 new binder.
1321 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1322 DebruijnIndex::from_u32(self.as_u32() + amount)
1325 /// Update this index in place by shifting it "in" through
1326 /// `amount` number of binders.
1327 pub fn shift_in(&mut self, amount: u32) {
1328 *self = self.shifted_in(amount);
1331 /// Returns the resulting index when this value is moved out from
1332 /// `amount` number of new binders.
1334 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1335 DebruijnIndex::from_u32(self.as_u32() - amount)
1338 /// Update in place by shifting out from `amount` binders.
1339 pub fn shift_out(&mut self, amount: u32) {
1340 *self = self.shifted_out(amount);
1343 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1344 /// innermost binder. That is, if we have something bound at `to_binder`,
1345 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1346 /// when moving a region out from inside binders:
1349 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1350 /// // Binder: D3 D2 D1 ^^
1353 /// Here, the region `'a` would have the debruijn index D3,
1354 /// because it is the bound 3 binders out. However, if we wanted
1355 /// to refer to that region `'a` in the second argument (the `_`),
1356 /// those two binders would not be in scope. In that case, we
1357 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1358 /// debruijn index of `'a` to D1 (the innermost binder).
1360 /// If we invoke `shift_out_to_binder` and the region is in fact
1361 /// bound by one of the binders we are shifting out of, that is an
1362 /// error (and should fail an assertion failure).
1363 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1364 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1368 impl_stable_hash_for!(struct DebruijnIndex { private });
1370 /// Region utilities
1372 /// Is this region named by the user?
1373 pub fn has_name(&self) -> bool {
1375 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1376 RegionKind::ReLateBound(_, br) => br.is_named(),
1377 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1378 RegionKind::ReScope(..) => false,
1379 RegionKind::ReStatic => true,
1380 RegionKind::ReVar(..) => false,
1381 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1382 RegionKind::ReEmpty => false,
1383 RegionKind::ReErased => false,
1384 RegionKind::ReClosureBound(..) => false,
1385 RegionKind::ReCanonical(..) => false,
1389 pub fn is_late_bound(&self) -> bool {
1391 ty::ReLateBound(..) => true,
1396 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1398 ty::ReLateBound(debruijn, _) => debruijn >= index,
1403 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1404 /// innermost binder. That is, if we have something bound at `to_binder`,
1405 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1406 /// when moving a region out from inside binders:
1409 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1410 /// // Binder: D3 D2 D1 ^^
1413 /// Here, the region `'a` would have the debruijn index D3,
1414 /// because it is the bound 3 binders out. However, if we wanted
1415 /// to refer to that region `'a` in the second argument (the `_`),
1416 /// those two binders would not be in scope. In that case, we
1417 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1418 /// debruijn index of `'a` to D1 (the innermost binder).
1420 /// If we invoke `shift_out_to_binder` and the region is in fact
1421 /// bound by one of the binders we are shifting out of, that is an
1422 /// error (and should fail an assertion failure).
1423 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1425 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1426 debruijn.shifted_out_to_binder(to_binder),
1433 pub fn keep_in_local_tcx(&self) -> bool {
1434 if let ty::ReVar(..) = self {
1441 pub fn type_flags(&self) -> TypeFlags {
1442 let mut flags = TypeFlags::empty();
1444 if self.keep_in_local_tcx() {
1445 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1450 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1451 flags = flags | TypeFlags::HAS_RE_INFER;
1453 ty::RePlaceholder(..) => {
1454 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1455 flags = flags | TypeFlags::HAS_RE_SKOL;
1457 ty::ReLateBound(..) => {
1458 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1460 ty::ReEarlyBound(..) => {
1461 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1462 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1467 ty::ReScope { .. } => {
1468 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1472 ty::ReCanonical(..) => {
1473 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1474 flags = flags | TypeFlags::HAS_CANONICAL_VARS;
1476 ty::ReClosureBound(..) => {
1477 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1482 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1483 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1486 debug!("type_flags({:?}) = {:?}", self, flags);
1491 /// Given an early-bound or free region, returns the def-id where it was bound.
1492 /// For example, consider the regions in this snippet of code:
1496 /// ^^ -- early bound, declared on an impl
1498 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1499 /// ^^ ^^ ^ anonymous, late-bound
1500 /// | early-bound, appears in where-clauses
1501 /// late-bound, appears only in fn args
1506 /// Here, `free_region_binding_scope('a)` would return the def-id
1507 /// of the impl, and for all the other highlighted regions, it
1508 /// would return the def-id of the function. In other cases (not shown), this
1509 /// function might return the def-id of a closure.
1510 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1512 ty::ReEarlyBound(br) => {
1513 tcx.parent_def_id(br.def_id).unwrap()
1515 ty::ReFree(fr) => fr.scope,
1516 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1522 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1523 pub fn is_unit(&self) -> bool {
1525 Tuple(ref tys) => tys.is_empty(),
1530 pub fn is_never(&self) -> bool {
1537 pub fn is_primitive(&self) -> bool {
1539 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1544 pub fn is_ty_var(&self) -> bool {
1546 Infer(TyVar(_)) => true,
1551 pub fn is_ty_infer(&self) -> bool {
1558 pub fn is_phantom_data(&self) -> bool {
1559 if let Adt(def, _) = self.sty {
1560 def.is_phantom_data()
1566 pub fn is_bool(&self) -> bool { self.sty == Bool }
1568 pub fn is_param(&self, index: u32) -> bool {
1570 ty::Param(ref data) => data.idx == index,
1575 pub fn is_self(&self) -> bool {
1577 Param(ref p) => p.is_self(),
1582 pub fn is_slice(&self) -> bool {
1584 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1585 Slice(_) | Str => true,
1593 pub fn is_simd(&self) -> bool {
1595 Adt(def, _) => def.repr.simd(),
1600 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1602 Array(ty, _) | Slice(ty) => ty,
1603 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1604 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1608 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1610 Adt(def, substs) => {
1611 def.non_enum_variant().fields[0].ty(tcx, substs)
1613 _ => bug!("simd_type called on invalid type")
1617 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1619 Adt(def, _) => def.non_enum_variant().fields.len(),
1620 _ => bug!("simd_size called on invalid type")
1624 pub fn is_region_ptr(&self) -> bool {
1631 pub fn is_mutable_pointer(&self) -> bool {
1633 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1634 Ref(_, _, hir::Mutability::MutMutable) => true,
1639 pub fn is_unsafe_ptr(&self) -> bool {
1641 RawPtr(_) => return true,
1646 /// Returns `true` if this type is an `Arc<T>`.
1647 pub fn is_arc(&self) -> bool {
1649 Adt(def, _) => def.is_arc(),
1654 /// Returns `true` if this type is an `Rc<T>`.
1655 pub fn is_rc(&self) -> bool {
1657 Adt(def, _) => def.is_rc(),
1662 pub fn is_box(&self) -> bool {
1664 Adt(def, _) => def.is_box(),
1669 /// panics if called on any type other than `Box<T>`
1670 pub fn boxed_ty(&self) -> Ty<'tcx> {
1672 Adt(def, substs) if def.is_box() => substs.type_at(0),
1673 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1677 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1678 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1679 /// contents are abstract to rustc.)
1680 pub fn is_scalar(&self) -> bool {
1682 Bool | Char | Int(_) | Float(_) | Uint(_) |
1683 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1684 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1689 /// Returns true if this type is a floating point type and false otherwise.
1690 pub fn is_floating_point(&self) -> bool {
1693 Infer(FloatVar(_)) => true,
1698 pub fn is_trait(&self) -> bool {
1700 Dynamic(..) => true,
1705 pub fn is_enum(&self) -> bool {
1707 Adt(adt_def, _) => {
1714 pub fn is_closure(&self) -> bool {
1716 Closure(..) => true,
1721 pub fn is_generator(&self) -> bool {
1723 Generator(..) => true,
1728 pub fn is_integral(&self) -> bool {
1730 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1735 pub fn is_fresh_ty(&self) -> bool {
1737 Infer(FreshTy(_)) => true,
1742 pub fn is_fresh(&self) -> bool {
1744 Infer(FreshTy(_)) => true,
1745 Infer(FreshIntTy(_)) => true,
1746 Infer(FreshFloatTy(_)) => true,
1751 pub fn is_char(&self) -> bool {
1758 pub fn is_fp(&self) -> bool {
1760 Infer(FloatVar(_)) | Float(_) => true,
1765 pub fn is_numeric(&self) -> bool {
1766 self.is_integral() || self.is_fp()
1769 pub fn is_signed(&self) -> bool {
1776 pub fn is_machine(&self) -> bool {
1778 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1779 Int(..) | Uint(..) | Float(..) => true,
1784 pub fn has_concrete_skeleton(&self) -> bool {
1786 Param(_) | Infer(_) | Error => false,
1791 /// Returns the type and mutability of *ty.
1793 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1794 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1795 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1797 Adt(def, _) if def.is_box() => {
1799 ty: self.boxed_ty(),
1800 mutbl: hir::MutImmutable,
1803 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1804 RawPtr(mt) if explicit => Some(mt),
1809 /// Returns the type of `ty[i]`.
1810 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1812 Array(ty, _) | Slice(ty) => Some(ty),
1817 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1819 FnDef(def_id, substs) => {
1820 tcx.fn_sig(def_id).subst(tcx, substs)
1823 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1827 pub fn is_fn(&self) -> bool {
1829 FnDef(..) | FnPtr(_) => true,
1834 pub fn is_impl_trait(&self) -> bool {
1841 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1843 Adt(adt, _) => Some(adt),
1848 /// Returns the regions directly referenced from this type (but
1849 /// not types reachable from this type via `walk_tys`). This
1850 /// ignores late-bound regions binders.
1851 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1853 Ref(region, _, _) => {
1856 Dynamic(ref obj, region) => {
1857 let mut v = vec![region];
1858 v.extend(obj.principal().skip_binder().substs.regions());
1861 Adt(_, substs) | Opaque(_, substs) => {
1862 substs.regions().collect()
1864 Closure(_, ClosureSubsts { ref substs }) |
1865 Generator(_, GeneratorSubsts { ref substs }, _) => {
1866 substs.regions().collect()
1868 Projection(ref data) | UnnormalizedProjection(ref data) => {
1869 data.substs.regions().collect()
1873 GeneratorWitness(..) |
1895 /// When we create a closure, we record its kind (i.e., what trait
1896 /// it implements) into its `ClosureSubsts` using a type
1897 /// parameter. This is kind of a phantom type, except that the
1898 /// most convenient thing for us to are the integral types. This
1899 /// function converts such a special type into the closure
1900 /// kind. To go the other way, use
1901 /// `tcx.closure_kind_ty(closure_kind)`.
1903 /// Note that during type checking, we use an inference variable
1904 /// to represent the closure kind, because it has not yet been
1905 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1906 /// is complete, that type variable will be unified.
1907 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1909 Int(int_ty) => match int_ty {
1910 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1911 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1912 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1913 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1918 Error => Some(ty::ClosureKind::Fn),
1920 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1924 /// Fast path helper for testing if a type is `Sized`.
1926 /// Returning true means the type is known to be sized. Returning
1927 /// `false` means nothing -- could be sized, might not be.
1928 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1930 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1931 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1932 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1933 ty::Char | ty::Ref(..) | ty::Generator(..) |
1934 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1935 ty::Never | ty::Error =>
1938 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
1942 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
1944 ty::Adt(def, _substs) =>
1945 def.sized_constraint(tcx).is_empty(),
1947 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
1949 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
1951 ty::Infer(ty::TyVar(_)) => false,
1954 ty::Infer(ty::FreshTy(_)) |
1955 ty::Infer(ty::FreshIntTy(_)) |
1956 ty::Infer(ty::FreshFloatTy(_)) =>
1957 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
1962 /// Typed constant value.
1963 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
1964 pub struct Const<'tcx> {
1967 pub val: ConstValue<'tcx>,
1970 impl<'tcx> Const<'tcx> {
1972 tcx: TyCtxt<'_, '_, 'tcx>,
1974 substs: &'tcx Substs<'tcx>,
1977 tcx.mk_const(Const {
1978 val: ConstValue::Unevaluated(def_id, substs),
1984 pub fn from_const_value(
1985 tcx: TyCtxt<'_, '_, 'tcx>,
1986 val: ConstValue<'tcx>,
1989 tcx.mk_const(Const {
1997 tcx: TyCtxt<'_, '_, 'tcx>,
2001 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
2006 tcx: TyCtxt<'_, '_, 'tcx>,
2008 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2010 let ty = tcx.lift_to_global(&ty).unwrap();
2011 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2012 panic!("could not compute layout for {:?}: {:?}", ty, e)
2014 let shift = 128 - size.bits();
2015 let truncated = (bits << shift) >> shift;
2016 assert_eq!(truncated, bits, "from_bits called with untruncated value");
2017 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
2021 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2022 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
2026 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
2027 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2031 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
2032 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2038 tcx: TyCtxt<'_, '_, 'tcx>,
2039 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2041 if self.ty != ty.value {
2044 let ty = tcx.lift_to_global(&ty).unwrap();
2045 let size = tcx.layout_of(ty).ok()?.size;
2046 self.val.try_to_bits(size)
2050 pub fn to_ptr(&self) -> Option<Pointer> {
2051 self.val.try_to_ptr()
2057 tcx: TyCtxt<'_, '_, '_>,
2058 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2060 assert_eq!(self.ty, ty.value);
2061 let ty = tcx.lift_to_global(&ty).unwrap();
2062 let size = tcx.layout_of(ty).ok()?.size;
2063 self.val.try_to_bits(size)
2067 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2068 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2076 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2077 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2083 tcx: TyCtxt<'_, '_, '_>,
2084 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2086 self.assert_bits(tcx, ty).unwrap_or_else(||
2087 bug!("expected bits of {}, got {:#?}", ty.value, self))
2091 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2092 self.assert_usize(tcx).unwrap_or_else(||
2093 bug!("expected constant usize, got {:#?}", self))
2097 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}