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.
14 use hir::def_id::DefId;
15 use infer::canonical::Canonical;
16 use mir::interpret::ConstValue;
18 use polonius_engine::Atom;
19 use rustc_data_structures::indexed_vec::Idx;
20 use ty::subst::{Substs, Subst, Kind, UnpackedKind};
21 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
22 use ty::{List, TyS, ParamEnvAnd, ParamEnv};
23 use util::captures::Captures;
24 use mir::interpret::{Scalar, Pointer};
26 use smallvec::SmallVec;
28 use std::cmp::Ordering;
29 use rustc_target::spec::abi;
30 use syntax::ast::{self, Ident};
31 use syntax::symbol::{keywords, InternedString};
37 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
38 pub struct TypeAndMut<'tcx> {
40 pub mutbl: hir::Mutability,
43 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
44 RustcEncodable, RustcDecodable, Copy)]
45 /// A "free" region `fr` can be interpreted as "some region
46 /// at least as big as the scope `fr.scope`".
47 pub struct FreeRegion {
49 pub bound_region: BoundRegion,
52 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
53 RustcEncodable, RustcDecodable, Copy)]
54 pub enum BoundRegion {
55 /// An anonymous region parameter for a given fn (&T)
58 /// Named region parameters for functions (a in &'a T)
60 /// The def-id is needed to distinguish free regions in
61 /// the event of shadowing.
62 BrNamed(DefId, InternedString),
64 /// Fresh bound identifiers created during GLB computations.
67 /// Anonymous region for the implicit env pointer parameter
73 pub fn is_named(&self) -> bool {
75 BoundRegion::BrNamed(..) => true,
80 /// When canonicalizing, we replace unbound inference variables and free
81 /// regions with anonymous late bound regions. This method asserts that
82 /// we have an anonymous late bound region, which hence may refer to
83 /// a canonical variable.
84 pub fn assert_bound_var(&self) -> BoundVar {
86 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
87 _ => bug!("bound region is not anonymous"),
92 /// N.B., if you change this, you'll probably want to change the corresponding
93 /// AST structure in `libsyntax/ast.rs` as well.
94 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
95 pub enum TyKind<'tcx> {
96 /// The primitive boolean type. Written as `bool`.
99 /// The primitive character type; holds a Unicode scalar value
100 /// (a non-surrogate code point). Written as `char`.
103 /// A primitive signed integer type. For example, `i32`.
106 /// A primitive unsigned integer type. For example, `u32`.
109 /// A primitive floating-point type. For example, `f64`.
112 /// Structures, enumerations and unions.
114 /// Substs here, possibly against intuition, *may* contain `Param`s.
115 /// That is, even after substitution it is possible that there are type
116 /// variables. This happens when the `Adt` corresponds to an ADT
117 /// definition and not a concrete use of it.
118 Adt(&'tcx AdtDef, &'tcx Substs<'tcx>),
122 /// The pointee of a string slice. Written as `str`.
125 /// An array with the given length. Written as `[T; n]`.
126 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
128 /// The pointee of an array slice. Written as `[T]`.
131 /// A raw pointer. Written as `*mut T` or `*const T`
132 RawPtr(TypeAndMut<'tcx>),
134 /// A reference; a pointer with an associated lifetime. Written as
135 /// `&'a mut T` or `&'a T`.
136 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
138 /// The anonymous type of a function declaration/definition. Each
139 /// function has a unique type, which is output (for a function
140 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
142 /// For example the type of `bar` here:
145 /// fn foo() -> i32 { 1 }
146 /// let bar = foo; // bar: fn() -> i32 {foo}
148 FnDef(DefId, &'tcx Substs<'tcx>),
150 /// A pointer to a function. Written as `fn() -> i32`.
152 /// For example the type of `bar` here:
155 /// fn foo() -> i32 { 1 }
156 /// let bar: fn() -> i32 = foo;
158 FnPtr(PolyFnSig<'tcx>),
160 /// A trait, defined with `trait`.
161 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
163 /// The anonymous type of a closure. Used to represent the type of
165 Closure(DefId, ClosureSubsts<'tcx>),
167 /// The anonymous type of a generator. Used to represent the type of
169 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
171 /// A type representin the types stored inside a generator.
172 /// This should only appear in GeneratorInteriors.
173 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
175 /// The never type `!`
178 /// A tuple type. For example, `(i32, bool)`.
179 Tuple(&'tcx List<Ty<'tcx>>),
181 /// The projection of an associated type. For example,
182 /// `<T as Trait<..>>::N`.
183 Projection(ProjectionTy<'tcx>),
185 /// A placeholder type used when we do not have enough information
186 /// to normalize the projection of an associated type to an
187 /// existing concrete type. Currently only used with chalk-engine.
188 UnnormalizedProjection(ProjectionTy<'tcx>),
190 /// Opaque (`impl Trait`) type found in a return type.
191 /// The `DefId` comes either from
192 /// * the `impl Trait` ast::Ty node,
193 /// * or the `existential type` declaration
194 /// The substitutions are for the generics of the function in question.
195 /// After typeck, the concrete type can be found in the `types` map.
196 Opaque(DefId, &'tcx Substs<'tcx>),
198 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
201 /// Bound type variable, used only when preparing a trait query.
202 Bound(ty::DebruijnIndex, BoundTy),
204 /// A placeholder type - universally quantified higher-ranked type.
205 Placeholder(ty::PlaceholderType),
207 /// A type variable used during type checking.
210 /// A placeholder for a type which could not be computed; this is
211 /// propagated to avoid useless error messages.
215 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
216 #[cfg(target_arch = "x86_64")]
217 static_assert!(MEM_SIZE_OF_TY_KIND: ::std::mem::size_of::<TyKind<'_>>() == 24);
219 /// A closure can be modeled as a struct that looks like:
221 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
229 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
230 /// in scope on the function that defined the closure,
231 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
232 /// is rather hackily encoded via a scalar type. See
233 /// `TyS::to_opt_closure_kind` for details.
234 /// - CS represents the *closure signature*, representing as a `fn()`
235 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
236 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
238 /// - U0...Uk are type parameters representing the types of its upvars
239 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
240 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
242 /// So, for example, given this function:
244 /// fn foo<'a, T>(data: &'a mut T) {
245 /// do(|| data.count += 1)
248 /// the type of the closure would be something like:
250 /// struct Closure<'a, T, U0> {
254 /// Note that the type of the upvar is not specified in the struct.
255 /// You may wonder how the impl would then be able to use the upvar,
256 /// if it doesn't know it's type? The answer is that the impl is
257 /// (conceptually) not fully generic over Closure but rather tied to
258 /// instances with the expected upvar types:
260 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
264 /// You can see that the *impl* fully specified the type of the upvar
265 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
266 /// (Here, I am assuming that `data` is mut-borrowed.)
268 /// Now, the last question you may ask is: Why include the upvar types
269 /// as extra type parameters? The reason for this design is that the
270 /// upvar types can reference lifetimes that are internal to the
271 /// creating function. In my example above, for example, the lifetime
272 /// `'b` represents the scope of the closure itself; this is some
273 /// subset of `foo`, probably just the scope of the call to the to
274 /// `do()`. If we just had the lifetime/type parameters from the
275 /// enclosing function, we couldn't name this lifetime `'b`. Note that
276 /// there can also be lifetimes in the types of the upvars themselves,
277 /// if one of them happens to be a reference to something that the
278 /// creating fn owns.
280 /// OK, you say, so why not create a more minimal set of parameters
281 /// that just includes the extra lifetime parameters? The answer is
282 /// primarily that it would be hard --- we don't know at the time when
283 /// we create the closure type what the full types of the upvars are,
284 /// nor do we know which are borrowed and which are not. In this
285 /// design, we can just supply a fresh type parameter and figure that
288 /// All right, you say, but why include the type parameters from the
289 /// original function then? The answer is that codegen may need them
290 /// when monomorphizing, and they may not appear in the upvars. A
291 /// closure could capture no variables but still make use of some
292 /// in-scope type parameter with a bound (e.g., if our example above
293 /// had an extra `U: Default`, and the closure called `U::default()`).
295 /// There is another reason. This design (implicitly) prohibits
296 /// closures from capturing themselves (except via a trait
297 /// object). This simplifies closure inference considerably, since it
298 /// means that when we infer the kind of a closure or its upvars, we
299 /// don't have to handle cycles where the decisions we make for
300 /// closure C wind up influencing the decisions we ought to make for
301 /// closure C (which would then require fixed point iteration to
302 /// handle). Plus it fixes an ICE. :P
306 /// Perhaps surprisingly, `ClosureSubsts` are also used for
307 /// generators. In that case, what is written above is only half-true
308 /// -- the set of type parameters is similar, but the role of CK and
309 /// CS are different. CK represents the "yield type" and CS
310 /// represents the "return type" of the generator.
312 /// It'd be nice to split this struct into ClosureSubsts and
313 /// GeneratorSubsts, I believe. -nmatsakis
314 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
315 pub struct ClosureSubsts<'tcx> {
316 /// Lifetime and type parameters from the enclosing function,
317 /// concatenated with the types of the upvars.
319 /// These are separated out because codegen wants to pass them around
320 /// when monomorphizing.
321 pub substs: &'tcx Substs<'tcx>,
324 /// Struct returned by `split()`. Note that these are subslices of the
325 /// parent slice and not canonical substs themselves.
326 struct SplitClosureSubsts<'tcx> {
327 closure_kind_ty: Ty<'tcx>,
328 closure_sig_ty: Ty<'tcx>,
329 upvar_kinds: &'tcx [Kind<'tcx>],
332 impl<'tcx> ClosureSubsts<'tcx> {
333 /// Divides the closure substs into their respective
334 /// components. Single source of truth with respect to the
336 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
337 let generics = tcx.generics_of(def_id);
338 let parent_len = generics.parent_count;
340 closure_kind_ty: self.substs.type_at(parent_len),
341 closure_sig_ty: self.substs.type_at(parent_len + 1),
342 upvar_kinds: &self.substs[parent_len + 2..],
347 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
348 impl Iterator<Item=Ty<'tcx>> + 'tcx
350 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
351 upvar_kinds.iter().map(|t| {
352 if let UnpackedKind::Type(ty) = t.unpack() {
355 bug!("upvar should be type")
360 /// Returns the closure kind for this closure; may return a type
361 /// variable during inference. To get the closure kind during
362 /// inference, use `infcx.closure_kind(def_id, substs)`.
363 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
364 self.split(def_id, tcx).closure_kind_ty
367 /// Returns the type representing the closure signature for this
368 /// closure; may contain type variables during inference. To get
369 /// the closure signature during inference, use
370 /// `infcx.fn_sig(def_id)`.
371 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
372 self.split(def_id, tcx).closure_sig_ty
375 /// Returns the closure kind for this closure; only usable outside
376 /// of an inference context, because in that context we know that
377 /// there are no type variables.
379 /// If you have an inference context, use `infcx.closure_kind()`.
380 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
381 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
384 /// Extracts the signature from the closure; only usable outside
385 /// of an inference context, because in that context we know that
386 /// there are no type variables.
388 /// If you have an inference context, use `infcx.closure_sig()`.
389 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
390 match self.closure_sig_ty(def_id, tcx).sty {
391 ty::FnPtr(sig) => sig,
392 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
397 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
398 pub struct GeneratorSubsts<'tcx> {
399 pub substs: &'tcx Substs<'tcx>,
402 struct SplitGeneratorSubsts<'tcx> {
406 upvar_kinds: &'tcx [Kind<'tcx>],
409 impl<'tcx> GeneratorSubsts<'tcx> {
410 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
411 let generics = tcx.generics_of(def_id);
412 let parent_len = generics.parent_count;
413 SplitGeneratorSubsts {
414 yield_ty: self.substs.type_at(parent_len),
415 return_ty: self.substs.type_at(parent_len + 1),
416 witness: self.substs.type_at(parent_len + 2),
417 upvar_kinds: &self.substs[parent_len + 3..],
421 /// This describes the types that can be contained in a generator.
422 /// It will be a type variable initially and unified in the last stages of typeck of a body.
423 /// It contains a tuple of all the types that could end up on a generator frame.
424 /// The state transformation MIR pass may only produce layouts which mention types
425 /// in this tuple. Upvars are not counted here.
426 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
427 self.split(def_id, tcx).witness
431 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
432 impl Iterator<Item=Ty<'tcx>> + 'tcx
434 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
435 upvar_kinds.iter().map(|t| {
436 if let UnpackedKind::Type(ty) = t.unpack() {
439 bug!("upvar should be type")
444 /// Returns the type representing the yield type of the generator.
445 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
446 self.split(def_id, tcx).yield_ty
449 /// Returns the type representing the return type of the generator.
450 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
451 self.split(def_id, tcx).return_ty
454 /// Return the "generator signature", which consists of its yield
455 /// and return types.
457 /// NB. Some bits of the code prefers to see this wrapped in a
458 /// binder, but it never contains bound regions. Probably this
459 /// function should be removed.
460 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
461 ty::Binder::dummy(self.sig(def_id, tcx))
464 /// Return the "generator signature", which consists of its yield
465 /// and return types.
466 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
468 yield_ty: self.yield_ty(def_id, tcx),
469 return_ty: self.return_ty(def_id, tcx),
474 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
475 /// This returns the types of the MIR locals which had to be stored across suspension points.
476 /// It is calculated in rustc_mir::transform::generator::StateTransform.
477 /// All the types here must be in the tuple in GeneratorInterior.
481 tcx: TyCtxt<'a, 'gcx, 'tcx>,
482 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
483 let state = tcx.generator_layout(def_id).fields.iter();
484 state.map(move |d| d.ty.subst(tcx, self.substs))
487 /// This is the types of the fields of a generate which
488 /// is available before the generator transformation.
489 /// It includes the upvars and the state discriminant which is u32.
490 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
491 impl Iterator<Item=Ty<'tcx>> + 'a
493 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
496 /// This is the types of all the fields stored in a generator.
497 /// It includes the upvars, state types and the state discriminant which is u32.
498 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
499 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
501 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
505 #[derive(Debug, Copy, Clone)]
506 pub enum UpvarSubsts<'tcx> {
507 Closure(ClosureSubsts<'tcx>),
508 Generator(GeneratorSubsts<'tcx>),
511 impl<'tcx> UpvarSubsts<'tcx> {
513 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
514 impl Iterator<Item=Ty<'tcx>> + 'tcx
516 let upvar_kinds = match self {
517 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
518 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
520 upvar_kinds.iter().map(|t| {
521 if let UnpackedKind::Type(ty) = t.unpack() {
524 bug!("upvar should be type")
530 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
531 pub enum ExistentialPredicate<'tcx> {
533 Trait(ExistentialTraitRef<'tcx>),
534 /// e.g., Iterator::Item = T
535 Projection(ExistentialProjection<'tcx>),
540 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
541 /// Compares via an ordering that will not change if modules are reordered or other changes are
542 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
543 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
544 use self::ExistentialPredicate::*;
545 match (*self, *other) {
546 (Trait(_), Trait(_)) => Ordering::Equal,
547 (Projection(ref a), Projection(ref b)) =>
548 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
549 (AutoTrait(ref a), AutoTrait(ref b)) =>
550 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
551 (Trait(_), _) => Ordering::Less,
552 (Projection(_), Trait(_)) => Ordering::Greater,
553 (Projection(_), _) => Ordering::Less,
554 (AutoTrait(_), _) => Ordering::Greater,
560 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
561 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
562 -> ty::Predicate<'tcx> {
564 match *self.skip_binder() {
565 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
566 ExistentialPredicate::Projection(p) =>
567 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
568 ExistentialPredicate::AutoTrait(did) => {
569 let trait_ref = Binder(ty::TraitRef {
571 substs: tcx.mk_substs_trait(self_ty, &[]),
573 trait_ref.to_predicate()
579 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
581 impl<'tcx> List<ExistentialPredicate<'tcx>> {
582 pub fn principal(&self) -> ExistentialTraitRef<'tcx> {
584 ExistentialPredicate::Trait(tr) => tr,
585 other => bug!("first predicate is {:?}", other),
590 pub fn projection_bounds<'a>(&'a self) ->
591 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
592 self.iter().filter_map(|predicate| {
594 ExistentialPredicate::Projection(p) => Some(p),
601 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
602 self.iter().filter_map(|predicate| {
604 ExistentialPredicate::AutoTrait(d) => Some(d),
611 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
612 pub fn principal(&self) -> PolyExistentialTraitRef<'tcx> {
613 Binder::bind(self.skip_binder().principal())
617 pub fn projection_bounds<'a>(&'a self) ->
618 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
619 self.skip_binder().projection_bounds().map(Binder::bind)
623 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
624 self.skip_binder().auto_traits()
627 pub fn iter<'a>(&'a self)
628 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
629 self.skip_binder().iter().cloned().map(Binder::bind)
633 /// A complete reference to a trait. These take numerous guises in syntax,
634 /// but perhaps the most recognizable form is in a where clause:
638 /// This would be represented by a trait-reference where the def-id is the
639 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
640 /// and `U` as parameter 1.
642 /// Trait references also appear in object types like `Foo<U>`, but in
643 /// that case the `Self` parameter is absent from the substitutions.
645 /// Note that a `TraitRef` introduces a level of region binding, to
646 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
647 /// or higher-ranked object types.
648 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
649 pub struct TraitRef<'tcx> {
651 pub substs: &'tcx Substs<'tcx>,
654 impl<'tcx> TraitRef<'tcx> {
655 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
656 TraitRef { def_id: def_id, substs: substs }
659 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
660 /// are the parameters defined on trait.
661 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
664 substs: Substs::identity_for_item(tcx, def_id),
669 pub fn self_ty(&self) -> Ty<'tcx> {
670 self.substs.type_at(0)
673 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
674 // Select only the "input types" from a trait-reference. For
675 // now this is all the types that appear in the
676 // trait-reference, but it should eventually exclude
681 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
683 substs: &Substs<'tcx>)
684 -> ty::TraitRef<'tcx> {
685 let defs = tcx.generics_of(trait_id);
689 substs: tcx.intern_substs(&substs[..defs.params.len()])
694 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
696 impl<'tcx> PolyTraitRef<'tcx> {
697 pub fn self_ty(&self) -> Ty<'tcx> {
698 self.skip_binder().self_ty()
701 pub fn def_id(&self) -> DefId {
702 self.skip_binder().def_id
705 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
706 // Note that we preserve binding levels
707 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
711 /// An existential reference to a trait, where `Self` is erased.
712 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
714 /// exists T. T: Trait<'a, 'b, X, Y>
716 /// The substitutions don't include the erased `Self`, only trait
717 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
718 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
719 pub struct ExistentialTraitRef<'tcx> {
721 pub substs: &'tcx Substs<'tcx>,
724 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
725 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
726 // Select only the "input types" from a trait-reference. For
727 // now this is all the types that appear in the
728 // trait-reference, but it should eventually exclude
733 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
734 trait_ref: ty::TraitRef<'tcx>)
735 -> ty::ExistentialTraitRef<'tcx> {
736 // Assert there is a Self.
737 trait_ref.substs.type_at(0);
739 ty::ExistentialTraitRef {
740 def_id: trait_ref.def_id,
741 substs: tcx.intern_substs(&trait_ref.substs[1..])
745 /// Object types don't have a self-type specified. Therefore, when
746 /// we convert the principal trait-ref into a normal trait-ref,
747 /// you must give *some* self-type. A common choice is `mk_err()`
748 /// or some placeholder type.
749 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
750 -> ty::TraitRef<'tcx> {
751 // otherwise the escaping vars would be captured by the binder
752 // debug_assert!(!self_ty.has_escaping_bound_vars());
756 substs: tcx.mk_substs_trait(self_ty, self.substs)
761 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
763 impl<'tcx> PolyExistentialTraitRef<'tcx> {
764 pub fn def_id(&self) -> DefId {
765 self.skip_binder().def_id
768 /// Object types don't have a self-type specified. Therefore, when
769 /// we convert the principal trait-ref into a normal trait-ref,
770 /// you must give *some* self-type. A common choice is `mk_err()`
771 /// or some placeholder type.
772 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
774 -> ty::PolyTraitRef<'tcx> {
775 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
779 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
780 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
781 /// (which would be represented by the type `PolyTraitRef ==
782 /// Binder<TraitRef>`). Note that when we instantiate,
783 /// erase, or otherwise "discharge" these bound vars, we change the
784 /// type from `Binder<T>` to just `T` (see
785 /// e.g., `liberate_late_bound_regions`).
786 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
787 pub struct Binder<T>(T);
790 /// Wraps `value` in a binder, asserting that `value` does not
791 /// contain any bound vars that would be bound by the
792 /// binder. This is commonly used to 'inject' a value T into a
793 /// different binding level.
794 pub fn dummy<'tcx>(value: T) -> Binder<T>
795 where T: TypeFoldable<'tcx>
797 debug_assert!(!value.has_escaping_bound_vars());
801 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
802 pub fn bind<'tcx>(value: T) -> Binder<T> {
806 /// Skips the binder and returns the "bound" value. This is a
807 /// risky thing to do because it's easy to get confused about
808 /// debruijn indices and the like. It is usually better to
809 /// discharge the binder using `no_bound_vars` or
810 /// `replace_late_bound_regions` or something like
811 /// that. `skip_binder` is only valid when you are either
812 /// extracting data that has nothing to do with bound vars, you
813 /// are doing some sort of test that does not involve bound
814 /// regions, or you are being very careful about your depth
817 /// Some examples where `skip_binder` is reasonable:
819 /// - extracting the def-id from a PolyTraitRef;
820 /// - comparing the self type of a PolyTraitRef to see if it is equal to
821 /// a type parameter `X`, since the type `X` does not reference any regions
822 pub fn skip_binder(&self) -> &T {
826 pub fn as_ref(&self) -> Binder<&T> {
830 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
831 where F: FnOnce(&T) -> U
833 self.as_ref().map_bound(f)
836 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
837 where F: FnOnce(T) -> U
842 /// Unwraps and returns the value within, but only if it contains
843 /// no bound vars at all. (In other words, if this binder --
844 /// and indeed any enclosing binder -- doesn't bind anything at
845 /// all.) Otherwise, returns `None`.
847 /// (One could imagine having a method that just unwraps a single
848 /// binder, but permits late-bound vars bound by enclosing
849 /// binders, but that would require adjusting the debruijn
850 /// indices, and given the shallow binding structure we often use,
851 /// would not be that useful.)
852 pub fn no_bound_vars<'tcx>(self) -> Option<T>
853 where T: TypeFoldable<'tcx>
855 if self.skip_binder().has_escaping_bound_vars() {
858 Some(self.skip_binder().clone())
862 /// Given two things that have the same binder level,
863 /// and an operation that wraps on their contents, execute the operation
864 /// and then wrap its result.
866 /// `f` should consider bound regions at depth 1 to be free, and
867 /// anything it produces with bound regions at depth 1 will be
868 /// bound in the resulting return value.
869 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
870 where F: FnOnce(T, U) -> R
872 Binder(f(self.0, u.0))
875 /// Split the contents into two things that share the same binder
876 /// level as the original, returning two distinct binders.
878 /// `f` should consider bound regions at depth 1 to be free, and
879 /// anything it produces with bound regions at depth 1 will be
880 /// bound in the resulting return values.
881 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
882 where F: FnOnce(T) -> (U, V)
884 let (u, v) = f(self.0);
885 (Binder(u), Binder(v))
889 /// Represents the projection of an associated type. In explicit UFCS
890 /// form this would be written `<T as Trait<..>>::N`.
891 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
892 pub struct ProjectionTy<'tcx> {
893 /// The parameters of the associated item.
894 pub substs: &'tcx Substs<'tcx>,
896 /// The `DefId` of the `TraitItem` for the associated type `N`.
898 /// Note that this is not the `DefId` of the `TraitRef` containing this
899 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
900 pub item_def_id: DefId,
903 impl<'a, 'tcx> ProjectionTy<'tcx> {
904 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
905 /// associated item named `item_name`.
906 pub fn from_ref_and_name(
907 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
908 ) -> ProjectionTy<'tcx> {
909 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
910 item.kind == ty::AssociatedKind::Type &&
911 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
915 substs: trait_ref.substs,
920 /// Extracts the underlying trait reference from this projection.
921 /// For example, if this is a projection of `<T as Iterator>::Item`,
922 /// then this function would return a `T: Iterator` trait reference.
923 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
924 let def_id = tcx.associated_item(self.item_def_id).container.id();
931 pub fn self_ty(&self) -> Ty<'tcx> {
932 self.substs.type_at(0)
936 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
937 pub struct GenSig<'tcx> {
938 pub yield_ty: Ty<'tcx>,
939 pub return_ty: Ty<'tcx>,
942 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
944 impl<'tcx> PolyGenSig<'tcx> {
945 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
946 self.map_bound_ref(|sig| sig.yield_ty)
948 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
949 self.map_bound_ref(|sig| sig.return_ty)
953 /// Signature of a function type, which I have arbitrarily
954 /// decided to use to refer to the input/output types.
956 /// - `inputs` is the list of arguments and their modes.
957 /// - `output` is the return type.
958 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
959 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
960 pub struct FnSig<'tcx> {
961 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
963 pub unsafety: hir::Unsafety,
967 impl<'tcx> FnSig<'tcx> {
968 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
969 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
972 pub fn output(&self) -> Ty<'tcx> {
973 self.inputs_and_output[self.inputs_and_output.len() - 1]
977 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
979 impl<'tcx> PolyFnSig<'tcx> {
981 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
982 self.map_bound_ref(|fn_sig| fn_sig.inputs())
985 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
986 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
988 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
989 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
992 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
993 self.map_bound_ref(|fn_sig| fn_sig.output())
995 pub fn variadic(&self) -> bool {
996 self.skip_binder().variadic
998 pub fn unsafety(&self) -> hir::Unsafety {
999 self.skip_binder().unsafety
1001 pub fn abi(&self) -> abi::Abi {
1002 self.skip_binder().abi
1006 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1009 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1010 pub struct ParamTy {
1012 pub name: InternedString,
1015 impl<'a, 'gcx, 'tcx> ParamTy {
1016 pub fn new(index: u32, name: InternedString) -> ParamTy {
1017 ParamTy { idx: index, name: name }
1020 pub fn for_self() -> ParamTy {
1021 ParamTy::new(0, keywords::SelfUpper.name().as_interned_str())
1024 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1025 ParamTy::new(def.index, def.name)
1028 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1029 tcx.mk_ty_param(self.idx, self.name)
1032 pub fn is_self(&self) -> bool {
1033 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
1034 // but this should only be possible when using `-Z continue-parse-after-error` like
1035 // `compile-fail/issue-36638.rs`.
1036 self.name == keywords::SelfUpper.name().as_str() && self.idx == 0
1040 /// A [De Bruijn index][dbi] is a standard means of representing
1041 /// regions (and perhaps later types) in a higher-ranked setting. In
1042 /// particular, imagine a type like this:
1044 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1047 /// | +------------+ 0 | |
1049 /// +--------------------------------+ 1 |
1051 /// +------------------------------------------+ 0
1053 /// In this type, there are two binders (the outer fn and the inner
1054 /// fn). We need to be able to determine, for any given region, which
1055 /// fn type it is bound by, the inner or the outer one. There are
1056 /// various ways you can do this, but a De Bruijn index is one of the
1057 /// more convenient and has some nice properties. The basic idea is to
1058 /// count the number of binders, inside out. Some examples should help
1059 /// clarify what I mean.
1061 /// Let's start with the reference type `&'b isize` that is the first
1062 /// argument to the inner function. This region `'b` is assigned a De
1063 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1064 /// fn). The region `'a` that appears in the second argument type (`&'a
1065 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1066 /// second-innermost binder". (These indices are written on the arrays
1067 /// in the diagram).
1069 /// What is interesting is that De Bruijn index attached to a particular
1070 /// variable will vary depending on where it appears. For example,
1071 /// the final type `&'a char` also refers to the region `'a` declared on
1072 /// the outermost fn. But this time, this reference is not nested within
1073 /// any other binders (i.e., it is not an argument to the inner fn, but
1074 /// rather the outer one). Therefore, in this case, it is assigned a
1075 /// De Bruijn index of 0, because the innermost binder in that location
1076 /// is the outer fn.
1078 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1080 pub struct DebruijnIndex {
1081 DEBUG_FORMAT = "DebruijnIndex({})",
1082 const INNERMOST = 0,
1086 pub type Region<'tcx> = &'tcx RegionKind;
1088 /// Representation of regions.
1090 /// Unlike types, most region variants are "fictitious", not concrete,
1091 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1092 /// ones representing concrete regions.
1094 /// ## Bound Regions
1096 /// These are regions that are stored behind a binder and must be substituted
1097 /// with some concrete region before being used. There are 2 kind of
1098 /// bound regions: early-bound, which are bound in an item's Generics,
1099 /// and are substituted by a Substs, and late-bound, which are part of
1100 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`) and are substituted by
1101 /// the likes of `liberate_late_bound_regions`. The distinction exists
1102 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1104 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1105 /// outside their binder, e.g., in types passed to type inference, and
1106 /// should first be substituted (by placeholder regions, free regions,
1107 /// or region variables).
1109 /// ## Placeholder and Free Regions
1111 /// One often wants to work with bound regions without knowing their precise
1112 /// identity. For example, when checking a function, the lifetime of a borrow
1113 /// can end up being assigned to some region parameter. In these cases,
1114 /// it must be ensured that bounds on the region can't be accidentally
1115 /// assumed without being checked.
1117 /// To do this, we replace the bound regions with placeholder markers,
1118 /// which don't satisfy any relation not explicitly provided.
1120 /// There are 2 kinds of placeholder regions in rustc: `ReFree` and
1121 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1122 /// to be used. These also support explicit bounds: both the internally-stored
1123 /// *scope*, which the region is assumed to outlive, as well as other
1124 /// relations stored in the `FreeRegionMap`. Note that these relations
1125 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1126 /// `resolve_regions_and_report_errors`.
1128 /// When working with higher-ranked types, some region relations aren't
1129 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1130 /// `RePlaceholder` is designed for this purpose. In these contexts,
1131 /// there's also the risk that some inference variable laying around will
1132 /// get unified with your placeholder region: if you want to check whether
1133 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1134 /// with a placeholder region `'%a`, the variable `'_` would just be
1135 /// instantiated to the placeholder region `'%a`, which is wrong because
1136 /// the inference variable is supposed to satisfy the relation
1137 /// *for every value of the placeholder region*. To ensure that doesn't
1138 /// happen, you can use `leak_check`. This is more clearly explained
1139 /// by the [rustc guide].
1141 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1142 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1143 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1144 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1145 pub enum RegionKind {
1146 // Region bound in a type or fn declaration which will be
1147 // substituted 'early' -- that is, at the same time when type
1148 // parameters are substituted.
1149 ReEarlyBound(EarlyBoundRegion),
1151 // Region bound in a function scope, which will be substituted when the
1152 // function is called.
1153 ReLateBound(DebruijnIndex, BoundRegion),
1155 /// When checking a function body, the types of all arguments and so forth
1156 /// that refer to bound region parameters are modified to refer to free
1157 /// region parameters.
1160 /// A concrete region naming some statically determined scope
1161 /// (e.g., an expression or sequence of statements) within the
1162 /// current function.
1163 ReScope(region::Scope),
1165 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1168 /// A region variable. Should not exist after typeck.
1171 /// A placeholder region - basically the higher-ranked version of ReFree.
1172 /// Should not exist after typeck.
1173 RePlaceholder(ty::PlaceholderRegion),
1175 /// Empty lifetime is for data that is never accessed.
1176 /// Bottom in the region lattice. We treat ReEmpty somewhat
1177 /// specially; at least right now, we do not generate instances of
1178 /// it during the GLB computations, but rather
1179 /// generate an error instead. This is to improve error messages.
1180 /// The only way to get an instance of ReEmpty is to have a region
1181 /// variable with no constraints.
1184 /// Erased region, used by trait selection, in MIR and during codegen.
1187 /// These are regions bound in the "defining type" for a
1188 /// closure. They are used ONLY as part of the
1189 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1190 /// See `ClosureRegionRequirements` for more details.
1191 ReClosureBound(RegionVid),
1194 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1196 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1197 pub struct EarlyBoundRegion {
1200 pub name: InternedString,
1203 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1208 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1213 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1214 pub struct FloatVid {
1219 pub struct RegionVid {
1220 DEBUG_FORMAT = custom,
1224 impl Atom for RegionVid {
1225 fn index(self) -> usize {
1230 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1236 /// A `FreshTy` is one that is generated as a replacement for an
1237 /// unbound type variable. This is convenient for caching etc. See
1238 /// `infer::freshen` for more details.
1245 pub struct BoundVar { .. }
1248 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1249 pub struct BoundTy {
1251 pub kind: BoundTyKind,
1254 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1255 pub enum BoundTyKind {
1257 Param(InternedString),
1260 impl_stable_hash_for!(struct BoundTy { var, kind });
1261 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1263 impl From<BoundVar> for BoundTy {
1264 fn from(var: BoundVar) -> Self {
1267 kind: BoundTyKind::Anon,
1272 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1273 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1274 pub struct ExistentialProjection<'tcx> {
1275 pub item_def_id: DefId,
1276 pub substs: &'tcx Substs<'tcx>,
1280 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1282 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1283 /// Extracts the underlying existential trait reference from this projection.
1284 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1285 /// then this function would return a `exists T. T: Iterator` existential trait
1287 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1288 let def_id = tcx.associated_item(self.item_def_id).container.id();
1289 ty::ExistentialTraitRef{
1291 substs: self.substs,
1295 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1297 -> ty::ProjectionPredicate<'tcx>
1299 // otherwise the escaping regions would be captured by the binders
1300 debug_assert!(!self_ty.has_escaping_bound_vars());
1302 ty::ProjectionPredicate {
1303 projection_ty: ty::ProjectionTy {
1304 item_def_id: self.item_def_id,
1305 substs: tcx.mk_substs_trait(self_ty, self.substs),
1312 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1313 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1314 -> ty::PolyProjectionPredicate<'tcx> {
1315 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1318 pub fn item_def_id(&self) -> DefId {
1319 return self.skip_binder().item_def_id;
1323 impl DebruijnIndex {
1324 /// Returns the resulting index when this value is moved into
1325 /// `amount` number of new binders. So e.g., if you had
1327 /// for<'a> fn(&'a x)
1329 /// and you wanted to change to
1331 /// for<'a> fn(for<'b> fn(&'a x))
1333 /// you would need to shift the index for `'a` into a new binder.
1335 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1336 DebruijnIndex::from_u32(self.as_u32() + amount)
1339 /// Update this index in place by shifting it "in" through
1340 /// `amount` number of binders.
1341 pub fn shift_in(&mut self, amount: u32) {
1342 *self = self.shifted_in(amount);
1345 /// Returns the resulting index when this value is moved out from
1346 /// `amount` number of new binders.
1348 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1349 DebruijnIndex::from_u32(self.as_u32() - amount)
1352 /// Update in place by shifting out from `amount` binders.
1353 pub fn shift_out(&mut self, amount: u32) {
1354 *self = self.shifted_out(amount);
1357 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1358 /// innermost binder. That is, if we have something bound at `to_binder`,
1359 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1360 /// when moving a region out from inside binders:
1363 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1364 /// // Binder: D3 D2 D1 ^^
1367 /// Here, the region `'a` would have the debruijn index D3,
1368 /// because it is the bound 3 binders out. However, if we wanted
1369 /// to refer to that region `'a` in the second argument (the `_`),
1370 /// those two binders would not be in scope. In that case, we
1371 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1372 /// debruijn index of `'a` to D1 (the innermost binder).
1374 /// If we invoke `shift_out_to_binder` and the region is in fact
1375 /// bound by one of the binders we are shifting out of, that is an
1376 /// error (and should fail an assertion failure).
1377 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1378 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1382 impl_stable_hash_for!(struct DebruijnIndex { private });
1384 /// Region utilities
1386 /// Is this region named by the user?
1387 pub fn has_name(&self) -> bool {
1389 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1390 RegionKind::ReLateBound(_, br) => br.is_named(),
1391 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1392 RegionKind::ReScope(..) => false,
1393 RegionKind::ReStatic => true,
1394 RegionKind::ReVar(..) => false,
1395 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1396 RegionKind::ReEmpty => false,
1397 RegionKind::ReErased => false,
1398 RegionKind::ReClosureBound(..) => false,
1402 pub fn is_late_bound(&self) -> bool {
1404 ty::ReLateBound(..) => true,
1409 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1411 ty::ReLateBound(debruijn, _) => debruijn >= index,
1416 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1417 /// innermost binder. That is, if we have something bound at `to_binder`,
1418 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1419 /// when moving a region out from inside binders:
1422 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1423 /// // Binder: D3 D2 D1 ^^
1426 /// Here, the region `'a` would have the debruijn index D3,
1427 /// because it is the bound 3 binders out. However, if we wanted
1428 /// to refer to that region `'a` in the second argument (the `_`),
1429 /// those two binders would not be in scope. In that case, we
1430 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1431 /// debruijn index of `'a` to D1 (the innermost binder).
1433 /// If we invoke `shift_out_to_binder` and the region is in fact
1434 /// bound by one of the binders we are shifting out of, that is an
1435 /// error (and should fail an assertion failure).
1436 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1438 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1439 debruijn.shifted_out_to_binder(to_binder),
1446 pub fn keep_in_local_tcx(&self) -> bool {
1447 if let ty::ReVar(..) = self {
1454 pub fn type_flags(&self) -> TypeFlags {
1455 let mut flags = TypeFlags::empty();
1457 if self.keep_in_local_tcx() {
1458 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1463 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1464 flags = flags | TypeFlags::HAS_RE_INFER;
1466 ty::RePlaceholder(..) => {
1467 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1468 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1470 ty::ReLateBound(..) => {
1471 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1473 ty::ReEarlyBound(..) => {
1474 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1475 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1480 ty::ReScope { .. } => {
1481 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1485 ty::ReClosureBound(..) => {
1486 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1491 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1492 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1495 debug!("type_flags({:?}) = {:?}", self, flags);
1500 /// Given an early-bound or free region, returns the def-id where it was bound.
1501 /// For example, consider the regions in this snippet of code:
1505 /// ^^ -- early bound, declared on an impl
1507 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1508 /// ^^ ^^ ^ anonymous, late-bound
1509 /// | early-bound, appears in where-clauses
1510 /// late-bound, appears only in fn args
1515 /// Here, `free_region_binding_scope('a)` would return the def-id
1516 /// of the impl, and for all the other highlighted regions, it
1517 /// would return the def-id of the function. In other cases (not shown), this
1518 /// function might return the def-id of a closure.
1519 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1521 ty::ReEarlyBound(br) => {
1522 tcx.parent_def_id(br.def_id).unwrap()
1524 ty::ReFree(fr) => fr.scope,
1525 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1531 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1532 pub fn is_unit(&self) -> bool {
1534 Tuple(ref tys) => tys.is_empty(),
1539 pub fn is_never(&self) -> bool {
1546 /// Checks whether a type is definitely uninhabited. This is
1547 /// conservative: for some types that are uninhabited we return `false`,
1548 /// but we only return `true` for types that are definitely uninhabited.
1549 /// `ty.conservative_is_uninhabited` implies that any value of type `ty`
1550 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1551 /// size, to account for partial initialisation. See #49298 for details.)
1552 pub fn conservative_is_uninhabited(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
1553 // FIXME(varkor): we can make this less conversative by substituting concrete
1557 ty::Adt(def, _) if def.is_union() => {
1558 // For now, `union`s are never considered uninhabited.
1561 ty::Adt(def, _) => {
1562 // Any ADT is uninhabited if either:
1563 // (a) It has no variants (i.e. an empty `enum`);
1564 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1565 // one uninhabited field.
1566 def.variants.iter().all(|var| {
1567 var.fields.iter().any(|field| {
1568 tcx.type_of(field.did).conservative_is_uninhabited(tcx)
1572 ty::Tuple(tys) => tys.iter().any(|ty| ty.conservative_is_uninhabited(tcx)),
1573 ty::Array(ty, len) => {
1574 match len.assert_usize(tcx) {
1575 // If the array is definitely non-empty, it's uninhabited if
1576 // the type of its elements is uninhabited.
1577 Some(n) if n != 0 => ty.conservative_is_uninhabited(tcx),
1582 // References to uninitialised memory is valid for any type, including
1583 // uninhabited types, in unsafe code, so we treat all references as
1591 pub fn is_primitive(&self) -> bool {
1593 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1599 pub fn is_ty_var(&self) -> bool {
1601 Infer(TyVar(_)) => true,
1606 pub fn is_ty_infer(&self) -> bool {
1613 pub fn is_phantom_data(&self) -> bool {
1614 if let Adt(def, _) = self.sty {
1615 def.is_phantom_data()
1621 pub fn is_bool(&self) -> bool { self.sty == Bool }
1623 pub fn is_param(&self, index: u32) -> bool {
1625 ty::Param(ref data) => data.idx == index,
1630 pub fn is_self(&self) -> bool {
1632 Param(ref p) => p.is_self(),
1637 pub fn is_slice(&self) -> bool {
1639 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1640 Slice(_) | Str => true,
1648 pub fn is_simd(&self) -> bool {
1650 Adt(def, _) => def.repr.simd(),
1655 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1657 Array(ty, _) | Slice(ty) => ty,
1658 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1659 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1663 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1665 Adt(def, substs) => {
1666 def.non_enum_variant().fields[0].ty(tcx, substs)
1668 _ => bug!("simd_type called on invalid type")
1672 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1674 Adt(def, _) => def.non_enum_variant().fields.len(),
1675 _ => bug!("simd_size called on invalid type")
1679 pub fn is_region_ptr(&self) -> bool {
1686 pub fn is_mutable_pointer(&self) -> bool {
1688 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1689 Ref(_, _, hir::Mutability::MutMutable) => true,
1694 pub fn is_unsafe_ptr(&self) -> bool {
1696 RawPtr(_) => return true,
1701 /// Returns `true` if this type is an `Arc<T>`.
1702 pub fn is_arc(&self) -> bool {
1704 Adt(def, _) => def.is_arc(),
1709 /// Returns `true` if this type is an `Rc<T>`.
1710 pub fn is_rc(&self) -> bool {
1712 Adt(def, _) => def.is_rc(),
1717 pub fn is_box(&self) -> bool {
1719 Adt(def, _) => def.is_box(),
1724 /// panics if called on any type other than `Box<T>`
1725 pub fn boxed_ty(&self) -> Ty<'tcx> {
1727 Adt(def, substs) if def.is_box() => substs.type_at(0),
1728 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1732 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1733 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1734 /// contents are abstract to rustc.)
1735 pub fn is_scalar(&self) -> bool {
1737 Bool | Char | Int(_) | Float(_) | Uint(_) |
1738 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1739 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1744 /// Returns true if this type is a floating point type and false otherwise.
1745 pub fn is_floating_point(&self) -> bool {
1748 Infer(FloatVar(_)) => true,
1753 pub fn is_trait(&self) -> bool {
1755 Dynamic(..) => true,
1760 pub fn is_enum(&self) -> bool {
1762 Adt(adt_def, _) => {
1769 pub fn is_closure(&self) -> bool {
1771 Closure(..) => true,
1776 pub fn is_generator(&self) -> bool {
1778 Generator(..) => true,
1784 pub fn is_integral(&self) -> bool {
1786 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1791 pub fn is_fresh_ty(&self) -> bool {
1793 Infer(FreshTy(_)) => true,
1798 pub fn is_fresh(&self) -> bool {
1800 Infer(FreshTy(_)) => true,
1801 Infer(FreshIntTy(_)) => true,
1802 Infer(FreshFloatTy(_)) => true,
1807 pub fn is_char(&self) -> bool {
1815 pub fn is_fp(&self) -> bool {
1817 Infer(FloatVar(_)) | Float(_) => true,
1822 pub fn is_numeric(&self) -> bool {
1823 self.is_integral() || self.is_fp()
1826 pub fn is_signed(&self) -> bool {
1833 pub fn is_pointer_sized(&self) -> bool {
1835 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
1840 pub fn is_machine(&self) -> bool {
1842 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1843 Int(..) | Uint(..) | Float(..) => true,
1848 pub fn has_concrete_skeleton(&self) -> bool {
1850 Param(_) | Infer(_) | Error => false,
1855 /// Returns the type and mutability of `*ty`.
1857 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1858 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1859 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1861 Adt(def, _) if def.is_box() => {
1863 ty: self.boxed_ty(),
1864 mutbl: hir::MutImmutable,
1867 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1868 RawPtr(mt) if explicit => Some(mt),
1873 /// Returns the type of `ty[i]`.
1874 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1876 Array(ty, _) | Slice(ty) => Some(ty),
1881 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1883 FnDef(def_id, substs) => {
1884 tcx.fn_sig(def_id).subst(tcx, substs)
1887 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1891 pub fn is_fn(&self) -> bool {
1893 FnDef(..) | FnPtr(_) => true,
1898 pub fn is_impl_trait(&self) -> bool {
1906 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1908 Adt(adt, _) => Some(adt),
1913 /// Push onto `out` the regions directly referenced from this type (but not
1914 /// types reachable from this type via `walk_tys`). This ignores late-bound
1915 /// regions binders.
1916 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
1918 Ref(region, _, _) => {
1921 Dynamic(ref obj, region) => {
1923 out.extend(obj.principal().skip_binder().substs.regions());
1925 Adt(_, substs) | Opaque(_, substs) => {
1926 out.extend(substs.regions())
1928 Closure(_, ClosureSubsts { ref substs }) |
1929 Generator(_, GeneratorSubsts { ref substs }, _) => {
1930 out.extend(substs.regions())
1932 Projection(ref data) | UnnormalizedProjection(ref data) => {
1933 out.extend(data.substs.regions())
1937 GeneratorWitness(..) |
1958 /// When we create a closure, we record its kind (i.e., what trait
1959 /// it implements) into its `ClosureSubsts` using a type
1960 /// parameter. This is kind of a phantom type, except that the
1961 /// most convenient thing for us to are the integral types. This
1962 /// function converts such a special type into the closure
1963 /// kind. To go the other way, use
1964 /// `tcx.closure_kind_ty(closure_kind)`.
1966 /// Note that during type checking, we use an inference variable
1967 /// to represent the closure kind, because it has not yet been
1968 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1969 /// is complete, that type variable will be unified.
1970 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1972 Int(int_ty) => match int_ty {
1973 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1974 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1975 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1976 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1981 Error => Some(ty::ClosureKind::Fn),
1983 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1987 /// Fast path helper for testing if a type is `Sized`.
1989 /// Returning true means the type is known to be sized. Returning
1990 /// `false` means nothing -- could be sized, might not be.
1991 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1993 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1994 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1995 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1996 ty::Char | ty::Ref(..) | ty::Generator(..) |
1997 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1998 ty::Never | ty::Error =>
2001 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2005 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
2007 ty::Adt(def, _substs) =>
2008 def.sized_constraint(tcx).is_empty(),
2010 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2012 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2014 ty::Infer(ty::TyVar(_)) => false,
2017 ty::Placeholder(..) |
2018 ty::Infer(ty::FreshTy(_)) |
2019 ty::Infer(ty::FreshIntTy(_)) |
2020 ty::Infer(ty::FreshFloatTy(_)) =>
2021 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2026 /// Typed constant value.
2027 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
2028 pub struct Const<'tcx> {
2031 pub val: ConstValue<'tcx>,
2034 impl<'tcx> Const<'tcx> {
2036 tcx: TyCtxt<'_, '_, 'tcx>,
2038 substs: &'tcx Substs<'tcx>,
2041 tcx.mk_const(Const {
2042 val: ConstValue::Unevaluated(def_id, substs),
2048 pub fn from_const_value(
2049 tcx: TyCtxt<'_, '_, 'tcx>,
2050 val: ConstValue<'tcx>,
2053 tcx.mk_const(Const {
2061 tcx: TyCtxt<'_, '_, 'tcx>,
2065 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
2070 tcx: TyCtxt<'_, '_, 'tcx>,
2072 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2074 let ty = tcx.lift_to_global(&ty).unwrap();
2075 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2076 panic!("could not compute layout for {:?}: {:?}", ty, e)
2078 let shift = 128 - size.bits();
2079 let truncated = (bits << shift) >> shift;
2080 assert_eq!(truncated, bits, "from_bits called with untruncated value");
2081 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
2085 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2086 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
2090 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
2091 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2095 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
2096 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2102 tcx: TyCtxt<'_, '_, 'tcx>,
2103 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2105 if self.ty != ty.value {
2108 let ty = tcx.lift_to_global(&ty).unwrap();
2109 let size = tcx.layout_of(ty).ok()?.size;
2110 self.val.try_to_bits(size)
2114 pub fn to_ptr(&self) -> Option<Pointer> {
2115 self.val.try_to_ptr()
2121 tcx: TyCtxt<'_, '_, '_>,
2122 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2124 assert_eq!(self.ty, ty.value);
2125 let ty = tcx.lift_to_global(&ty).unwrap();
2126 let size = tcx.layout_of(ty).ok()?.size;
2127 self.val.try_to_bits(size)
2131 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2132 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2140 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2141 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2147 tcx: TyCtxt<'_, '_, '_>,
2148 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2150 self.assert_bits(tcx, ty).unwrap_or_else(||
2151 bug!("expected bits of {}, got {:#?}", ty.value, self))
2155 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2156 self.assert_usize(tcx).unwrap_or_else(||
2157 bug!("expected constant usize, got {:#?}", self))
2161 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}