1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! This module contains TyKind and its major components
13 use hir::def_id::DefId;
15 use mir::interpret::ConstValue;
17 use polonius_engine::Atom;
18 use rustc_data_structures::indexed_vec::Idx;
19 use ty::subst::{Substs, Subst, Kind, UnpackedKind};
20 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
21 use ty::{List, TyS, ParamEnvAnd, ParamEnv};
22 use util::captures::Captures;
23 use mir::interpret::{Scalar, Pointer};
26 use std::cmp::Ordering;
27 use rustc_target::spec::abi;
28 use syntax::ast::{self, Ident};
29 use syntax::symbol::{keywords, InternedString};
38 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
39 pub struct TypeAndMut<'tcx> {
41 pub mutbl: hir::Mutability,
44 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
45 RustcEncodable, RustcDecodable, Copy)]
46 /// A "free" region `fr` can be interpreted as "some region
47 /// at least as big as the scope `fr.scope`".
48 pub struct FreeRegion {
50 pub bound_region: BoundRegion,
53 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
54 RustcEncodable, RustcDecodable, Copy)]
55 pub enum BoundRegion {
56 /// An anonymous region parameter for a given fn (&T)
59 /// Named region parameters for functions (a in &'a T)
61 /// The def-id is needed to distinguish free regions in
62 /// the event of shadowing.
63 BrNamed(DefId, InternedString),
65 /// Fresh bound identifiers created during GLB computations.
68 /// Anonymous region for the implicit env pointer parameter
74 pub fn is_named(&self) -> bool {
76 BoundRegion::BrNamed(..) => true,
82 /// N.B., If you change this, you'll probably want to change the corresponding
83 /// AST structure in `libsyntax/ast.rs` as well.
84 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
85 pub enum TyKind<'tcx> {
86 /// The primitive boolean type. Written as `bool`.
89 /// The primitive character type; holds a Unicode scalar value
90 /// (a non-surrogate code point). Written as `char`.
93 /// A primitive signed integer type. For example, `i32`.
96 /// A primitive unsigned integer type. For example, `u32`.
99 /// A primitive floating-point type. For example, `f64`.
102 /// Structures, enumerations and unions.
104 /// Substs here, possibly against intuition, *may* contain `Param`s.
105 /// That is, even after substitution it is possible that there are type
106 /// variables. This happens when the `Adt` corresponds to an ADT
107 /// definition and not a concrete use of it.
108 Adt(&'tcx AdtDef, &'tcx Substs<'tcx>),
112 /// The pointee of a string slice. Written as `str`.
115 /// An array with the given length. Written as `[T; n]`.
116 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
118 /// The pointee of an array slice. Written as `[T]`.
121 /// A raw pointer. Written as `*mut T` or `*const T`
122 RawPtr(TypeAndMut<'tcx>),
124 /// A reference; a pointer with an associated lifetime. Written as
125 /// `&'a mut T` or `&'a T`.
126 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
128 /// The anonymous type of a function declaration/definition. Each
129 /// function has a unique type.
130 FnDef(DefId, &'tcx Substs<'tcx>),
132 /// A pointer to a function. Written as `fn() -> i32`.
133 FnPtr(PolyFnSig<'tcx>),
135 /// A trait, defined with `trait`.
136 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
138 /// The anonymous type of a closure. Used to represent the type of
140 Closure(DefId, ClosureSubsts<'tcx>),
142 /// The anonymous type of a generator. Used to represent the type of
144 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
146 /// A type representin the types stored inside a generator.
147 /// This should only appear in GeneratorInteriors.
148 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
150 /// The never type `!`
153 /// A tuple type. For example, `(i32, bool)`.
154 Tuple(&'tcx List<Ty<'tcx>>),
156 /// The projection of an associated type. For example,
157 /// `<T as Trait<..>>::N`.
158 Projection(ProjectionTy<'tcx>),
160 /// Opaque (`impl Trait`) type found in a return type.
161 /// The `DefId` comes either from
162 /// * the `impl Trait` ast::Ty node,
163 /// * or the `existential type` declaration
164 /// The substitutions are for the generics of the function in question.
165 /// After typeck, the concrete type can be found in the `types` map.
166 Opaque(DefId, &'tcx Substs<'tcx>),
168 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
171 /// A type variable used during type checking.
174 /// A placeholder for a type which could not be computed; this is
175 /// propagated to avoid useless error messages.
179 /// A closure can be modeled as a struct that looks like:
181 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
189 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
190 /// in scope on the function that defined the closure,
191 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
192 /// is rather hackily encoded via a scalar type. See
193 /// `TyS::to_opt_closure_kind` for details.
194 /// - CS represents the *closure signature*, representing as a `fn()`
195 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
196 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
198 /// - U0...Uk are type parameters representing the types of its upvars
199 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
200 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
202 /// So, for example, given this function:
204 /// fn foo<'a, T>(data: &'a mut T) {
205 /// do(|| data.count += 1)
208 /// the type of the closure would be something like:
210 /// struct Closure<'a, T, U0> {
214 /// Note that the type of the upvar is not specified in the struct.
215 /// You may wonder how the impl would then be able to use the upvar,
216 /// if it doesn't know it's type? The answer is that the impl is
217 /// (conceptually) not fully generic over Closure but rather tied to
218 /// instances with the expected upvar types:
220 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
224 /// You can see that the *impl* fully specified the type of the upvar
225 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
226 /// (Here, I am assuming that `data` is mut-borrowed.)
228 /// Now, the last question you may ask is: Why include the upvar types
229 /// as extra type parameters? The reason for this design is that the
230 /// upvar types can reference lifetimes that are internal to the
231 /// creating function. In my example above, for example, the lifetime
232 /// `'b` represents the scope of the closure itself; this is some
233 /// subset of `foo`, probably just the scope of the call to the to
234 /// `do()`. If we just had the lifetime/type parameters from the
235 /// enclosing function, we couldn't name this lifetime `'b`. Note that
236 /// there can also be lifetimes in the types of the upvars themselves,
237 /// if one of them happens to be a reference to something that the
238 /// creating fn owns.
240 /// OK, you say, so why not create a more minimal set of parameters
241 /// that just includes the extra lifetime parameters? The answer is
242 /// primarily that it would be hard --- we don't know at the time when
243 /// we create the closure type what the full types of the upvars are,
244 /// nor do we know which are borrowed and which are not. In this
245 /// design, we can just supply a fresh type parameter and figure that
248 /// All right, you say, but why include the type parameters from the
249 /// original function then? The answer is that codegen may need them
250 /// when monomorphizing, and they may not appear in the upvars. A
251 /// closure could capture no variables but still make use of some
252 /// in-scope type parameter with a bound (e.g., if our example above
253 /// had an extra `U: Default`, and the closure called `U::default()`).
255 /// There is another reason. This design (implicitly) prohibits
256 /// closures from capturing themselves (except via a trait
257 /// object). This simplifies closure inference considerably, since it
258 /// means that when we infer the kind of a closure or its upvars, we
259 /// don't have to handle cycles where the decisions we make for
260 /// closure C wind up influencing the decisions we ought to make for
261 /// closure C (which would then require fixed point iteration to
262 /// handle). Plus it fixes an ICE. :P
266 /// Perhaps surprisingly, `ClosureSubsts` are also used for
267 /// generators. In that case, what is written above is only half-true
268 /// -- the set of type parameters is similar, but the role of CK and
269 /// CS are different. CK represents the "yield type" and CS
270 /// represents the "return type" of the generator.
272 /// It'd be nice to split this struct into ClosureSubsts and
273 /// GeneratorSubsts, I believe. -nmatsakis
274 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
275 pub struct ClosureSubsts<'tcx> {
276 /// Lifetime and type parameters from the enclosing function,
277 /// concatenated with the types of the upvars.
279 /// These are separated out because codegen wants to pass them around
280 /// when monomorphizing.
281 pub substs: &'tcx Substs<'tcx>,
284 /// Struct returned by `split()`. Note that these are subslices of the
285 /// parent slice and not canonical substs themselves.
286 struct SplitClosureSubsts<'tcx> {
287 closure_kind_ty: Ty<'tcx>,
288 closure_sig_ty: Ty<'tcx>,
289 upvar_kinds: &'tcx [Kind<'tcx>],
292 impl<'tcx> ClosureSubsts<'tcx> {
293 /// Divides the closure substs into their respective
294 /// components. Single source of truth with respect to the
296 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
297 let generics = tcx.generics_of(def_id);
298 let parent_len = generics.parent_count;
300 closure_kind_ty: self.substs.type_at(parent_len),
301 closure_sig_ty: self.substs.type_at(parent_len + 1),
302 upvar_kinds: &self.substs[parent_len + 2..],
307 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
308 impl Iterator<Item=Ty<'tcx>> + 'tcx
310 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
311 upvar_kinds.iter().map(|t| {
312 if let UnpackedKind::Type(ty) = t.unpack() {
315 bug!("upvar should be type")
320 /// Returns the closure kind for this closure; may return a type
321 /// variable during inference. To get the closure kind during
322 /// inference, use `infcx.closure_kind(def_id, substs)`.
323 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
324 self.split(def_id, tcx).closure_kind_ty
327 /// Returns the type representing the closure signature for this
328 /// closure; may contain type variables during inference. To get
329 /// the closure signature during inference, use
330 /// `infcx.fn_sig(def_id)`.
331 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
332 self.split(def_id, tcx).closure_sig_ty
335 /// Returns the closure kind for this closure; only usable outside
336 /// of an inference context, because in that context we know that
337 /// there are no type variables.
339 /// If you have an inference context, use `infcx.closure_kind()`.
340 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
341 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
344 /// Extracts the signature from the closure; only usable outside
345 /// of an inference context, because in that context we know that
346 /// there are no type variables.
348 /// If you have an inference context, use `infcx.closure_sig()`.
349 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
350 match self.closure_sig_ty(def_id, tcx).sty {
351 ty::FnPtr(sig) => sig,
352 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
357 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
358 pub struct GeneratorSubsts<'tcx> {
359 pub substs: &'tcx Substs<'tcx>,
362 struct SplitGeneratorSubsts<'tcx> {
366 upvar_kinds: &'tcx [Kind<'tcx>],
369 impl<'tcx> GeneratorSubsts<'tcx> {
370 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
371 let generics = tcx.generics_of(def_id);
372 let parent_len = generics.parent_count;
373 SplitGeneratorSubsts {
374 yield_ty: self.substs.type_at(parent_len),
375 return_ty: self.substs.type_at(parent_len + 1),
376 witness: self.substs.type_at(parent_len + 2),
377 upvar_kinds: &self.substs[parent_len + 3..],
381 /// This describes the types that can be contained in a generator.
382 /// It will be a type variable initially and unified in the last stages of typeck of a body.
383 /// It contains a tuple of all the types that could end up on a generator frame.
384 /// The state transformation MIR pass may only produce layouts which mention types
385 /// in this tuple. Upvars are not counted here.
386 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
387 self.split(def_id, tcx).witness
391 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
392 impl Iterator<Item=Ty<'tcx>> + 'tcx
394 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
395 upvar_kinds.iter().map(|t| {
396 if let UnpackedKind::Type(ty) = t.unpack() {
399 bug!("upvar should be type")
404 /// Returns the type representing the yield type of the generator.
405 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
406 self.split(def_id, tcx).yield_ty
409 /// Returns the type representing the return type of the generator.
410 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
411 self.split(def_id, tcx).return_ty
414 /// Return the "generator signature", which consists of its yield
415 /// and return types.
417 /// NB. Some bits of the code prefers to see this wrapped in a
418 /// binder, but it never contains bound regions. Probably this
419 /// function should be removed.
420 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
421 ty::Binder::dummy(self.sig(def_id, tcx))
424 /// Return the "generator signature", which consists of its yield
425 /// and return types.
426 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
428 yield_ty: self.yield_ty(def_id, tcx),
429 return_ty: self.return_ty(def_id, tcx),
434 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
435 /// This returns the types of the MIR locals which had to be stored across suspension points.
436 /// It is calculated in rustc_mir::transform::generator::StateTransform.
437 /// All the types here must be in the tuple in GeneratorInterior.
441 tcx: TyCtxt<'a, 'gcx, 'tcx>,
442 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
443 let state = tcx.generator_layout(def_id).fields.iter();
444 state.map(move |d| d.ty.subst(tcx, self.substs))
447 /// This is the types of the fields of a generate which
448 /// is available before the generator transformation.
449 /// It includes the upvars and the state discriminant which is u32.
450 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
451 impl Iterator<Item=Ty<'tcx>> + 'a
453 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
456 /// This is the types of all the fields stored in a generator.
457 /// It includes the upvars, state types and the state discriminant which is u32.
458 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
459 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
461 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
465 #[derive(Debug, Copy, Clone)]
466 pub enum UpvarSubsts<'tcx> {
467 Closure(ClosureSubsts<'tcx>),
468 Generator(GeneratorSubsts<'tcx>),
471 impl<'tcx> UpvarSubsts<'tcx> {
473 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
474 impl Iterator<Item=Ty<'tcx>> + 'tcx
476 let upvar_kinds = match self {
477 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
478 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
480 upvar_kinds.iter().map(|t| {
481 if let UnpackedKind::Type(ty) = t.unpack() {
484 bug!("upvar should be type")
490 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
491 pub enum ExistentialPredicate<'tcx> {
493 Trait(ExistentialTraitRef<'tcx>),
494 /// e.g. Iterator::Item = T
495 Projection(ExistentialProjection<'tcx>),
500 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
501 /// Compares via an ordering that will not change if modules are reordered or other changes are
502 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
503 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
504 use self::ExistentialPredicate::*;
505 match (*self, *other) {
506 (Trait(_), Trait(_)) => Ordering::Equal,
507 (Projection(ref a), Projection(ref b)) =>
508 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
509 (AutoTrait(ref a), AutoTrait(ref b)) =>
510 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
511 (Trait(_), _) => Ordering::Less,
512 (Projection(_), Trait(_)) => Ordering::Greater,
513 (Projection(_), _) => Ordering::Less,
514 (AutoTrait(_), _) => Ordering::Greater,
520 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
521 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
522 -> ty::Predicate<'tcx> {
524 match *self.skip_binder() {
525 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
526 ExistentialPredicate::Projection(p) =>
527 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
528 ExistentialPredicate::AutoTrait(did) => {
529 let trait_ref = Binder(ty::TraitRef {
531 substs: tcx.mk_substs_trait(self_ty, &[]),
533 trait_ref.to_predicate()
539 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
541 impl<'tcx> List<ExistentialPredicate<'tcx>> {
542 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
544 Some(&ExistentialPredicate::Trait(tr)) => Some(tr),
550 pub fn projection_bounds<'a>(&'a self) ->
551 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
552 self.iter().filter_map(|predicate| {
554 ExistentialPredicate::Projection(p) => Some(p),
561 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
562 self.iter().filter_map(|predicate| {
564 ExistentialPredicate::AutoTrait(d) => Some(d),
571 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
572 pub fn principal(&self) -> Option<PolyExistentialTraitRef<'tcx>> {
573 self.skip_binder().principal().map(Binder::bind)
577 pub fn projection_bounds<'a>(&'a self) ->
578 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
579 self.skip_binder().projection_bounds().map(Binder::bind)
583 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
584 self.skip_binder().auto_traits()
587 pub fn iter<'a>(&'a self)
588 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
589 self.skip_binder().iter().cloned().map(Binder::bind)
593 /// A complete reference to a trait. These take numerous guises in syntax,
594 /// but perhaps the most recognizable form is in a where clause:
598 /// This would be represented by a trait-reference where the def-id is the
599 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
600 /// and `U` as parameter 1.
602 /// Trait references also appear in object types like `Foo<U>`, but in
603 /// that case the `Self` parameter is absent from the substitutions.
605 /// Note that a `TraitRef` introduces a level of region binding, to
606 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
607 /// U>` or higher-ranked object types.
608 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
609 pub struct TraitRef<'tcx> {
611 pub substs: &'tcx Substs<'tcx>,
614 impl<'tcx> TraitRef<'tcx> {
615 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
616 TraitRef { def_id: def_id, substs: substs }
619 /// Returns a TraitRef of the form `P0: Foo<P1..Pn>` where `Pi`
620 /// are the parameters defined on trait.
621 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
624 substs: Substs::identity_for_item(tcx, def_id),
628 pub fn self_ty(&self) -> Ty<'tcx> {
629 self.substs.type_at(0)
632 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
633 // Select only the "input types" from a trait-reference. For
634 // now this is all the types that appear in the
635 // trait-reference, but it should eventually exclude
640 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
642 substs: &Substs<'tcx>)
643 -> ty::TraitRef<'tcx> {
644 let defs = tcx.generics_of(trait_id);
648 substs: tcx.intern_substs(&substs[..defs.params.len()])
653 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
655 impl<'tcx> PolyTraitRef<'tcx> {
656 pub fn self_ty(&self) -> Ty<'tcx> {
657 self.skip_binder().self_ty()
660 pub fn def_id(&self) -> DefId {
661 self.skip_binder().def_id
664 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
665 // Note that we preserve binding levels
666 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
670 /// An existential reference to a trait, where `Self` is erased.
671 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
673 /// exists T. T: Trait<'a, 'b, X, Y>
675 /// The substitutions don't include the erased `Self`, only trait
676 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
677 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
678 pub struct ExistentialTraitRef<'tcx> {
680 pub substs: &'tcx Substs<'tcx>,
683 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
684 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
685 // Select only the "input types" from a trait-reference. For
686 // now this is all the types that appear in the
687 // trait-reference, but it should eventually exclude
692 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
693 trait_ref: ty::TraitRef<'tcx>)
694 -> ty::ExistentialTraitRef<'tcx> {
695 // Assert there is a Self.
696 trait_ref.substs.type_at(0);
698 ty::ExistentialTraitRef {
699 def_id: trait_ref.def_id,
700 substs: tcx.intern_substs(&trait_ref.substs[1..])
704 /// Object types don't have a self-type specified. Therefore, when
705 /// we convert the principal trait-ref into a normal trait-ref,
706 /// you must give *some* self-type. A common choice is `mk_err()`
707 /// or some skolemized type.
708 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
709 -> ty::TraitRef<'tcx> {
710 // otherwise the escaping regions would be captured by the binder
711 // debug_assert!(!self_ty.has_escaping_regions());
715 substs: tcx.mk_substs_trait(self_ty, self.substs)
720 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
722 impl<'tcx> PolyExistentialTraitRef<'tcx> {
723 pub fn def_id(&self) -> DefId {
724 self.skip_binder().def_id
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 skolemized type.
731 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
733 -> ty::PolyTraitRef<'tcx> {
734 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
738 /// Binder is a binder for higher-ranked lifetimes. It is part of the
739 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
740 /// (which would be represented by the type `PolyTraitRef ==
741 /// Binder<TraitRef>`). Note that when we skolemize, instantiate,
742 /// erase, or otherwise "discharge" these bound regions, we change the
743 /// type from `Binder<T>` to just `T` (see
744 /// e.g. `liberate_late_bound_regions`).
745 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
746 pub struct Binder<T>(T);
749 /// Wraps `value` in a binder, asserting that `value` does not
750 /// contain any bound regions that would be bound by the
751 /// binder. This is commonly used to 'inject' a value T into a
752 /// different binding level.
753 pub fn dummy<'tcx>(value: T) -> Binder<T>
754 where T: TypeFoldable<'tcx>
756 debug_assert!(!value.has_escaping_regions());
760 /// Wraps `value` in a binder, binding late-bound regions (if any).
761 pub fn bind<'tcx>(value: T) -> Binder<T>
766 /// Skips the binder and returns the "bound" value. This is a
767 /// risky thing to do because it's easy to get confused about
768 /// debruijn indices and the like. It is usually better to
769 /// discharge the binder using `no_late_bound_regions` or
770 /// `replace_late_bound_regions` or something like
771 /// that. `skip_binder` is only valid when you are either
772 /// extracting data that has nothing to do with bound regions, you
773 /// are doing some sort of test that does not involve bound
774 /// regions, or you are being very careful about your depth
777 /// Some examples where `skip_binder` is reasonable:
779 /// - extracting the def-id from a PolyTraitRef;
780 /// - comparing the self type of a PolyTraitRef to see if it is equal to
781 /// a type parameter `X`, since the type `X` does not reference any regions
782 pub fn skip_binder(&self) -> &T {
786 pub fn as_ref(&self) -> Binder<&T> {
790 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
791 where F: FnOnce(&T) -> U
793 self.as_ref().map_bound(f)
796 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
797 where F: FnOnce(T) -> U
802 /// Unwraps and returns the value within, but only if it contains
803 /// no bound regions at all. (In other words, if this binder --
804 /// and indeed any enclosing binder -- doesn't bind anything at
805 /// all.) Otherwise, returns `None`.
807 /// (One could imagine having a method that just unwraps a single
808 /// binder, but permits late-bound regions bound by enclosing
809 /// binders, but that would require adjusting the debruijn
810 /// indices, and given the shallow binding structure we often use,
811 /// would not be that useful.)
812 pub fn no_late_bound_regions<'tcx>(self) -> Option<T>
813 where T : TypeFoldable<'tcx>
815 if self.skip_binder().has_escaping_regions() {
818 Some(self.skip_binder().clone())
822 /// Given two things that have the same binder level,
823 /// and an operation that wraps on their contents, execute the operation
824 /// and then wrap its result.
826 /// `f` should consider bound regions at depth 1 to be free, and
827 /// anything it produces with bound regions at depth 1 will be
828 /// bound in the resulting return value.
829 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
830 where F: FnOnce(T, U) -> R
832 Binder(f(self.0, u.0))
835 /// Split the contents into two things that share the same binder
836 /// level as the original, returning two distinct binders.
838 /// `f` should consider bound regions at depth 1 to be free, and
839 /// anything it produces with bound regions at depth 1 will be
840 /// bound in the resulting return values.
841 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
842 where F: FnOnce(T) -> (U, V)
844 let (u, v) = f(self.0);
845 (Binder(u), Binder(v))
849 /// Represents the projection of an associated type. In explicit UFCS
850 /// form this would be written `<T as Trait<..>>::N`.
851 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
852 pub struct ProjectionTy<'tcx> {
853 /// The parameters of the associated item.
854 pub substs: &'tcx Substs<'tcx>,
856 /// The DefId of the TraitItem for the associated type N.
858 /// Note that this is not the DefId of the TraitRef containing this
859 /// associated type, which is in tcx.associated_item(item_def_id).container.
860 pub item_def_id: DefId,
863 impl<'a, 'tcx> ProjectionTy<'tcx> {
864 /// Construct a ProjectionTy by searching the trait from trait_ref for the
865 /// associated item named item_name.
866 pub fn from_ref_and_name(
867 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
868 ) -> ProjectionTy<'tcx> {
869 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
870 item.kind == ty::AssociatedKind::Type &&
871 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
875 substs: trait_ref.substs,
880 /// Extracts the underlying trait reference from this projection.
881 /// For example, if this is a projection of `<T as Iterator>::Item`,
882 /// then this function would return a `T: Iterator` trait reference.
883 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
884 let def_id = tcx.associated_item(self.item_def_id).container.id();
891 pub fn self_ty(&self) -> Ty<'tcx> {
892 self.substs.type_at(0)
896 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
897 pub struct GenSig<'tcx> {
898 pub yield_ty: Ty<'tcx>,
899 pub return_ty: Ty<'tcx>,
902 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
904 impl<'tcx> PolyGenSig<'tcx> {
905 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
906 self.map_bound_ref(|sig| sig.yield_ty)
908 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
909 self.map_bound_ref(|sig| sig.return_ty)
913 /// Signature of a function type, which I have arbitrarily
914 /// decided to use to refer to the input/output types.
916 /// - `inputs` is the list of arguments and their modes.
917 /// - `output` is the return type.
918 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
919 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
920 pub struct FnSig<'tcx> {
921 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
923 pub unsafety: hir::Unsafety,
927 impl<'tcx> FnSig<'tcx> {
928 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
929 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
932 pub fn output(&self) -> Ty<'tcx> {
933 self.inputs_and_output[self.inputs_and_output.len() - 1]
937 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
939 impl<'tcx> PolyFnSig<'tcx> {
940 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
941 self.map_bound_ref(|fn_sig| fn_sig.inputs())
943 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
944 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
946 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
947 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
949 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
950 self.map_bound_ref(|fn_sig| fn_sig.output().clone())
952 pub fn variadic(&self) -> bool {
953 self.skip_binder().variadic
955 pub fn unsafety(&self) -> hir::Unsafety {
956 self.skip_binder().unsafety
958 pub fn abi(&self) -> abi::Abi {
959 self.skip_binder().abi
963 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
966 pub name: InternedString,
969 impl<'a, 'gcx, 'tcx> ParamTy {
970 pub fn new(index: u32, name: InternedString) -> ParamTy {
971 ParamTy { idx: index, name: name }
974 pub fn for_self() -> ParamTy {
975 ParamTy::new(0, keywords::SelfType.name().as_interned_str())
978 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
979 ParamTy::new(def.index, def.name)
982 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
983 tcx.mk_ty_param(self.idx, self.name)
986 pub fn is_self(&self) -> bool {
987 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
988 // but this should only be possible when using `-Z continue-parse-after-error` like
989 // `compile-fail/issue-36638.rs`.
990 if self.name == keywords::SelfType.name().as_str() && self.idx == 0 {
998 /// A [De Bruijn index][dbi] is a standard means of representing
999 /// regions (and perhaps later types) in a higher-ranked setting. In
1000 /// particular, imagine a type like this:
1002 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1005 /// | +------------+ 0 | |
1007 /// +--------------------------------+ 1 |
1009 /// +------------------------------------------+ 0
1011 /// In this type, there are two binders (the outer fn and the inner
1012 /// fn). We need to be able to determine, for any given region, which
1013 /// fn type it is bound by, the inner or the outer one. There are
1014 /// various ways you can do this, but a De Bruijn index is one of the
1015 /// more convenient and has some nice properties. The basic idea is to
1016 /// count the number of binders, inside out. Some examples should help
1017 /// clarify what I mean.
1019 /// Let's start with the reference type `&'b isize` that is the first
1020 /// argument to the inner function. This region `'b` is assigned a De
1021 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1022 /// fn). The region `'a` that appears in the second argument type (`&'a
1023 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1024 /// second-innermost binder". (These indices are written on the arrays
1025 /// in the diagram).
1027 /// What is interesting is that De Bruijn index attached to a particular
1028 /// variable will vary depending on where it appears. For example,
1029 /// the final type `&'a char` also refers to the region `'a` declared on
1030 /// the outermost fn. But this time, this reference is not nested within
1031 /// any other binders (i.e., it is not an argument to the inner fn, but
1032 /// rather the outer one). Therefore, in this case, it is assigned a
1033 /// De Bruijn index of 0, because the innermost binder in that location
1034 /// is the outer fn.
1036 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1038 pub struct DebruijnIndex {
1039 DEBUG_FORMAT = "DebruijnIndex({})",
1040 const INNERMOST = 0,
1044 pub type Region<'tcx> = &'tcx RegionKind;
1046 /// Representation of regions.
1048 /// Unlike types, most region variants are "fictitious", not concrete,
1049 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1050 /// ones representing concrete regions.
1052 /// ## Bound Regions
1054 /// These are regions that are stored behind a binder and must be substituted
1055 /// with some concrete region before being used. There are 2 kind of
1056 /// bound regions: early-bound, which are bound in an item's Generics,
1057 /// and are substituted by a Substs, and late-bound, which are part of
1058 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
1059 /// the likes of `liberate_late_bound_regions`. The distinction exists
1060 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1062 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1063 /// outside their binder, e.g. in types passed to type inference, and
1064 /// should first be substituted (by skolemized regions, free regions,
1065 /// or region variables).
1067 /// ## Skolemized and Free Regions
1069 /// One often wants to work with bound regions without knowing their precise
1070 /// identity. For example, when checking a function, the lifetime of a borrow
1071 /// can end up being assigned to some region parameter. In these cases,
1072 /// it must be ensured that bounds on the region can't be accidentally
1073 /// assumed without being checked.
1075 /// The process of doing that is called "skolemization". The bound regions
1076 /// are replaced by skolemized markers, which don't satisfy any relation
1077 /// not explicitly provided.
1079 /// There are 2 kinds of skolemized regions in rustc: `ReFree` and
1080 /// `ReSkolemized`. When checking an item's body, `ReFree` is supposed
1081 /// to be used. These also support explicit bounds: both the internally-stored
1082 /// *scope*, which the region is assumed to outlive, as well as other
1083 /// relations stored in the `FreeRegionMap`. Note that these relations
1084 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1085 /// `resolve_regions_and_report_errors`.
1087 /// When working with higher-ranked types, some region relations aren't
1088 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1089 /// `ReSkolemized` is designed for this purpose. In these contexts,
1090 /// there's also the risk that some inference variable laying around will
1091 /// get unified with your skolemized region: if you want to check whether
1092 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1093 /// with a skolemized region `'%a`, the variable `'_` would just be
1094 /// instantiated to the skolemized region `'%a`, which is wrong because
1095 /// the inference variable is supposed to satisfy the relation
1096 /// *for every value of the skolemized region*. To ensure that doesn't
1097 /// happen, you can use `leak_check`. This is more clearly explained
1098 /// by the [rustc guide].
1100 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1101 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1102 /// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/traits/hrtb.html
1103 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1104 pub enum RegionKind {
1105 // Region bound in a type or fn declaration which will be
1106 // substituted 'early' -- that is, at the same time when type
1107 // parameters are substituted.
1108 ReEarlyBound(EarlyBoundRegion),
1110 // Region bound in a function scope, which will be substituted when the
1111 // function is called.
1112 ReLateBound(DebruijnIndex, BoundRegion),
1114 /// When checking a function body, the types of all arguments and so forth
1115 /// that refer to bound region parameters are modified to refer to free
1116 /// region parameters.
1119 /// A concrete region naming some statically determined scope
1120 /// (e.g. an expression or sequence of statements) within the
1121 /// current function.
1122 ReScope(region::Scope),
1124 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1127 /// A region variable. Should not exist after typeck.
1130 /// A skolemized region - basically the higher-ranked version of ReFree.
1131 /// Should not exist after typeck.
1132 ReSkolemized(ty::UniverseIndex, BoundRegion),
1134 /// Empty lifetime is for data that is never accessed.
1135 /// Bottom in the region lattice. We treat ReEmpty somewhat
1136 /// specially; at least right now, we do not generate instances of
1137 /// it during the GLB computations, but rather
1138 /// generate an error instead. This is to improve error messages.
1139 /// The only way to get an instance of ReEmpty is to have a region
1140 /// variable with no constraints.
1143 /// Erased region, used by trait selection, in MIR and during codegen.
1146 /// These are regions bound in the "defining type" for a
1147 /// closure. They are used ONLY as part of the
1148 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1149 /// See `ClosureRegionRequirements` for more details.
1150 ReClosureBound(RegionVid),
1152 /// Canonicalized region, used only when preparing a trait query.
1153 ReCanonical(CanonicalVar),
1156 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1158 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1159 pub struct EarlyBoundRegion {
1162 pub name: InternedString,
1165 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1170 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1175 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1176 pub struct FloatVid {
1181 pub struct RegionVid {
1182 DEBUG_FORMAT = custom,
1186 impl Atom for RegionVid {
1187 fn index(self) -> usize {
1192 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1198 /// A `FreshTy` is one that is generated as a replacement for an
1199 /// unbound type variable. This is convenient for caching etc. See
1200 /// `infer::freshen` for more details.
1205 /// Canonicalized type variable, used only when preparing a trait query.
1206 CanonicalTy(CanonicalVar),
1210 pub struct CanonicalVar { .. }
1213 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1214 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1215 pub struct ExistentialProjection<'tcx> {
1216 pub item_def_id: DefId,
1217 pub substs: &'tcx Substs<'tcx>,
1221 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1223 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1224 /// Extracts the underlying existential trait reference from this projection.
1225 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1226 /// then this function would return a `exists T. T: Iterator` existential trait
1228 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1229 let def_id = tcx.associated_item(self.item_def_id).container.id();
1230 ty::ExistentialTraitRef{
1232 substs: self.substs,
1236 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1238 -> ty::ProjectionPredicate<'tcx>
1240 // otherwise the escaping regions would be captured by the binders
1241 debug_assert!(!self_ty.has_escaping_regions());
1243 ty::ProjectionPredicate {
1244 projection_ty: ty::ProjectionTy {
1245 item_def_id: self.item_def_id,
1246 substs: tcx.mk_substs_trait(self_ty, self.substs),
1253 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1254 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1255 -> ty::PolyProjectionPredicate<'tcx> {
1256 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1259 pub fn item_def_id(&self) -> DefId {
1260 return self.skip_binder().item_def_id;
1264 impl DebruijnIndex {
1265 /// Returns the resulting index when this value is moved into
1266 /// `amount` number of new binders. So e.g. if you had
1268 /// for<'a> fn(&'a x)
1270 /// and you wanted to change to
1272 /// for<'a> fn(for<'b> fn(&'a x))
1274 /// you would need to shift the index for `'a` into 1 new binder.
1276 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1277 DebruijnIndex::from_u32(self.as_u32() + amount)
1280 /// Update this index in place by shifting it "in" through
1281 /// `amount` number of binders.
1282 pub fn shift_in(&mut self, amount: u32) {
1283 *self = self.shifted_in(amount);
1286 /// Returns the resulting index when this value is moved out from
1287 /// `amount` number of new binders.
1289 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1290 DebruijnIndex::from_u32(self.as_u32() - amount)
1293 /// Update in place by shifting out from `amount` binders.
1294 pub fn shift_out(&mut self, amount: u32) {
1295 *self = self.shifted_out(amount);
1298 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1299 /// innermost binder. That is, if we have something bound at `to_binder`,
1300 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1301 /// when moving a region out from inside binders:
1304 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1305 /// // Binder: D3 D2 D1 ^^
1308 /// Here, the region `'a` would have the debruijn index D3,
1309 /// because it is the bound 3 binders out. However, if we wanted
1310 /// to refer to that region `'a` in the second argument (the `_`),
1311 /// those two binders would not be in scope. In that case, we
1312 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1313 /// debruijn index of `'a` to D1 (the innermost binder).
1315 /// If we invoke `shift_out_to_binder` and the region is in fact
1316 /// bound by one of the binders we are shifting out of, that is an
1317 /// error (and should fail an assertion failure).
1318 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1319 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1323 impl_stable_hash_for!(struct DebruijnIndex { private });
1325 /// Region utilities
1327 /// Is this region named by the user?
1328 pub fn has_name(&self) -> bool {
1330 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1331 RegionKind::ReLateBound(_, br) => br.is_named(),
1332 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1333 RegionKind::ReScope(..) => false,
1334 RegionKind::ReStatic => true,
1335 RegionKind::ReVar(..) => false,
1336 RegionKind::ReSkolemized(_, br) => br.is_named(),
1337 RegionKind::ReEmpty => false,
1338 RegionKind::ReErased => false,
1339 RegionKind::ReClosureBound(..) => false,
1340 RegionKind::ReCanonical(..) => false,
1344 pub fn is_late_bound(&self) -> bool {
1346 ty::ReLateBound(..) => true,
1351 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1353 ty::ReLateBound(debruijn, _) => debruijn >= index,
1358 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1359 /// innermost binder. That is, if we have something bound at `to_binder`,
1360 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1361 /// when moving a region out from inside binders:
1364 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1365 /// // Binder: D3 D2 D1 ^^
1368 /// Here, the region `'a` would have the debruijn index D3,
1369 /// because it is the bound 3 binders out. However, if we wanted
1370 /// to refer to that region `'a` in the second argument (the `_`),
1371 /// those two binders would not be in scope. In that case, we
1372 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1373 /// debruijn index of `'a` to D1 (the innermost binder).
1375 /// If we invoke `shift_out_to_binder` and the region is in fact
1376 /// bound by one of the binders we are shifting out of, that is an
1377 /// error (and should fail an assertion failure).
1378 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1380 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1381 debruijn.shifted_out_to_binder(to_binder),
1388 pub fn keep_in_local_tcx(&self) -> bool {
1389 if let ty::ReVar(..) = self {
1396 pub fn type_flags(&self) -> TypeFlags {
1397 let mut flags = TypeFlags::empty();
1399 if self.keep_in_local_tcx() {
1400 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1405 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1406 flags = flags | TypeFlags::HAS_RE_INFER;
1408 ty::ReSkolemized(..) => {
1409 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1410 flags = flags | TypeFlags::HAS_RE_SKOL;
1412 ty::ReLateBound(..) => {
1413 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1415 ty::ReEarlyBound(..) => {
1416 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1417 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1422 ty::ReScope { .. } => {
1423 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1427 ty::ReCanonical(..) => {
1428 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1429 flags = flags | TypeFlags::HAS_CANONICAL_VARS;
1431 ty::ReClosureBound(..) => {
1432 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1437 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1438 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1441 debug!("type_flags({:?}) = {:?}", self, flags);
1446 /// Given an early-bound or free region, returns the def-id where it was bound.
1447 /// For example, consider the regions in this snippet of code:
1451 /// ^^ -- early bound, declared on an impl
1453 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1454 /// ^^ ^^ ^ anonymous, late-bound
1455 /// | early-bound, appears in where-clauses
1456 /// late-bound, appears only in fn args
1461 /// Here, `free_region_binding_scope('a)` would return the def-id
1462 /// of the impl, and for all the other highlighted regions, it
1463 /// would return the def-id of the function. In other cases (not shown), this
1464 /// function might return the def-id of a closure.
1465 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1467 ty::ReEarlyBound(br) => {
1468 tcx.parent_def_id(br.def_id).unwrap()
1470 ty::ReFree(fr) => fr.scope,
1471 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1477 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1478 pub fn is_unit(&self) -> bool {
1480 Tuple(ref tys) => tys.is_empty(),
1485 pub fn is_never(&self) -> bool {
1492 pub fn is_primitive(&self) -> bool {
1494 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1499 pub fn is_ty_var(&self) -> bool {
1501 Infer(TyVar(_)) => true,
1506 pub fn is_ty_infer(&self) -> bool {
1513 pub fn is_phantom_data(&self) -> bool {
1514 if let Adt(def, _) = self.sty {
1515 def.is_phantom_data()
1521 pub fn is_bool(&self) -> bool { self.sty == Bool }
1523 pub fn is_param(&self, index: u32) -> bool {
1525 ty::Param(ref data) => data.idx == index,
1530 pub fn is_self(&self) -> bool {
1532 Param(ref p) => p.is_self(),
1537 pub fn is_slice(&self) -> bool {
1539 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1540 Slice(_) | Str => true,
1548 pub fn is_simd(&self) -> bool {
1550 Adt(def, _) => def.repr.simd(),
1555 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1557 Array(ty, _) | Slice(ty) => ty,
1558 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1559 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1563 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1565 Adt(def, substs) => {
1566 def.non_enum_variant().fields[0].ty(tcx, substs)
1568 _ => bug!("simd_type called on invalid type")
1572 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1574 Adt(def, _) => def.non_enum_variant().fields.len(),
1575 _ => bug!("simd_size called on invalid type")
1579 pub fn is_region_ptr(&self) -> bool {
1586 pub fn is_mutable_pointer(&self) -> bool {
1588 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1589 Ref(_, _, hir::Mutability::MutMutable) => true,
1594 pub fn is_unsafe_ptr(&self) -> bool {
1596 RawPtr(_) => return true,
1601 pub fn is_box(&self) -> bool {
1603 Adt(def, _) => def.is_box(),
1608 /// panics if called on any type other than `Box<T>`
1609 pub fn boxed_ty(&self) -> Ty<'tcx> {
1611 Adt(def, substs) if def.is_box() => substs.type_at(0),
1612 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1616 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1617 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1618 /// contents are abstract to rustc.)
1619 pub fn is_scalar(&self) -> bool {
1621 Bool | Char | Int(_) | Float(_) | Uint(_) |
1622 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1623 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1628 /// Returns true if this type is a floating point type and false otherwise.
1629 pub fn is_floating_point(&self) -> bool {
1632 Infer(FloatVar(_)) => true,
1637 pub fn is_trait(&self) -> bool {
1639 Dynamic(..) => true,
1644 pub fn is_enum(&self) -> bool {
1646 Adt(adt_def, _) => {
1653 pub fn is_closure(&self) -> bool {
1655 Closure(..) => true,
1660 pub fn is_generator(&self) -> bool {
1662 Generator(..) => true,
1667 pub fn is_integral(&self) -> bool {
1669 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1674 pub fn is_fresh_ty(&self) -> bool {
1676 Infer(FreshTy(_)) => true,
1681 pub fn is_fresh(&self) -> bool {
1683 Infer(FreshTy(_)) => true,
1684 Infer(FreshIntTy(_)) => true,
1685 Infer(FreshFloatTy(_)) => true,
1690 pub fn is_char(&self) -> bool {
1697 pub fn is_fp(&self) -> bool {
1699 Infer(FloatVar(_)) | Float(_) => true,
1704 pub fn is_numeric(&self) -> bool {
1705 self.is_integral() || self.is_fp()
1708 pub fn is_signed(&self) -> bool {
1715 pub fn is_machine(&self) -> bool {
1717 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1718 Int(..) | Uint(..) | Float(..) => true,
1723 pub fn has_concrete_skeleton(&self) -> bool {
1725 Param(_) | Infer(_) | Error => false,
1730 /// Returns the type and mutability of *ty.
1732 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1733 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1734 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1736 Adt(def, _) if def.is_box() => {
1738 ty: self.boxed_ty(),
1739 mutbl: hir::MutImmutable,
1742 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1743 RawPtr(mt) if explicit => Some(mt),
1748 /// Returns the type of `ty[i]`.
1749 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1751 Array(ty, _) | Slice(ty) => Some(ty),
1756 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1758 FnDef(def_id, substs) => {
1759 tcx.fn_sig(def_id).subst(tcx, substs)
1762 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1766 pub fn is_fn(&self) -> bool {
1768 FnDef(..) | FnPtr(_) => true,
1773 pub fn is_impl_trait(&self) -> bool {
1780 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1782 Adt(adt, _) => Some(adt),
1787 /// Returns the regions directly referenced from this type (but
1788 /// not types reachable from this type via `walk_tys`). This
1789 /// ignores late-bound regions binders.
1790 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1792 Ref(region, _, _) => {
1795 Dynamic(ref obj, region) => {
1796 let mut v = vec![region];
1797 if let Some(p) = obj.principal() {
1798 v.extend(p.skip_binder().substs.regions());
1802 Adt(_, substs) | Opaque(_, substs) => {
1803 substs.regions().collect()
1805 Closure(_, ClosureSubsts { ref substs }) |
1806 Generator(_, GeneratorSubsts { ref substs }, _) => {
1807 substs.regions().collect()
1809 Projection(ref data) => {
1810 data.substs.regions().collect()
1814 GeneratorWitness(..) |
1835 /// When we create a closure, we record its kind (i.e., what trait
1836 /// it implements) into its `ClosureSubsts` using a type
1837 /// parameter. This is kind of a phantom type, except that the
1838 /// most convenient thing for us to are the integral types. This
1839 /// function converts such a special type into the closure
1840 /// kind. To go the other way, use
1841 /// `tcx.closure_kind_ty(closure_kind)`.
1843 /// Note that during type checking, we use an inference variable
1844 /// to represent the closure kind, because it has not yet been
1845 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1846 /// is complete, that type variable will be unified.
1847 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1849 Int(int_ty) => match int_ty {
1850 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1851 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1852 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1853 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1858 Error => Some(ty::ClosureKind::Fn),
1860 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1864 /// Fast path helper for testing if a type is `Sized`.
1866 /// Returning true means the type is known to be sized. Returning
1867 /// `false` means nothing -- could be sized, might not be.
1868 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1870 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1871 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1872 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1873 ty::Char | ty::Ref(..) | ty::Generator(..) |
1874 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1875 ty::Never | ty::Error =>
1878 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
1882 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
1884 ty::Adt(def, _substs) =>
1885 def.sized_constraint(tcx).is_empty(),
1887 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
1889 ty::Infer(ty::TyVar(_)) => false,
1891 ty::Infer(ty::CanonicalTy(_)) |
1892 ty::Infer(ty::FreshTy(_)) |
1893 ty::Infer(ty::FreshIntTy(_)) |
1894 ty::Infer(ty::FreshFloatTy(_)) =>
1895 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
1900 /// Typed constant value.
1901 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
1902 pub struct Const<'tcx> {
1905 pub val: ConstValue<'tcx>,
1908 impl<'tcx> Const<'tcx> {
1910 tcx: TyCtxt<'_, '_, 'tcx>,
1912 substs: &'tcx Substs<'tcx>,
1915 tcx.mk_const(Const {
1916 val: ConstValue::Unevaluated(def_id, substs),
1922 pub fn from_const_value(
1923 tcx: TyCtxt<'_, '_, 'tcx>,
1924 val: ConstValue<'tcx>,
1927 tcx.mk_const(Const {
1935 tcx: TyCtxt<'_, '_, 'tcx>,
1939 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
1944 tcx: TyCtxt<'_, '_, 'tcx>,
1946 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
1948 let ty = tcx.lift_to_global(&ty).unwrap();
1949 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
1950 panic!("could not compute layout for {:?}: {:?}", ty, e)
1952 let shift = 128 - size.bits();
1953 let truncated = (bits << shift) >> shift;
1954 assert_eq!(truncated, bits, "from_bits called with untruncated value");
1955 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
1959 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
1960 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
1964 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
1965 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
1969 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
1970 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
1976 tcx: TyCtxt<'_, '_, 'tcx>,
1977 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
1979 if self.ty != ty.value {
1982 let ty = tcx.lift_to_global(&ty).unwrap();
1983 let size = tcx.layout_of(ty).ok()?.size;
1984 self.val.try_to_bits(size)
1988 pub fn to_ptr(&self) -> Option<Pointer> {
1989 self.val.try_to_ptr()
1995 tcx: TyCtxt<'_, '_, '_>,
1996 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
1998 assert_eq!(self.ty, ty.value);
1999 let ty = tcx.lift_to_global(&ty).unwrap();
2000 let size = tcx.layout_of(ty).ok()?.size;
2001 self.val.try_to_bits(size)
2005 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2006 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2014 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2015 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2021 tcx: TyCtxt<'_, '_, '_>,
2022 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2024 match self.assert_bits(tcx, ty) {
2026 None => bug!("expected bits of {}, got {:#?}", ty.value, self),
2031 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2032 match self.assert_usize(tcx) {
2034 None => bug!("expected constant usize, got {:#?}", self),
2039 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}