1 //! This module contains `TyKind` and its major components.
4 use crate::hir::def_id::DefId;
5 use crate::infer::canonical::Canonical;
6 use crate::mir::interpret::ConstValue;
7 use crate::middle::region;
8 use polonius_engine::Atom;
9 use rustc_data_structures::indexed_vec::Idx;
10 use rustc_macros::HashStable;
11 use crate::ty::subst::{InternalSubsts, Subst, SubstsRef, Kind, UnpackedKind};
12 use crate::ty::{self, AdtDef, Discr, DefIdTree, TypeFlags, Ty, TyCtxt, TypeFoldable};
13 use crate::ty::{List, TyS, ParamEnvAnd, ParamEnv};
14 use crate::ty::layout::VariantIdx;
15 use crate::util::captures::Captures;
16 use crate::mir::interpret::{Scalar, Pointer};
18 use smallvec::SmallVec;
20 use std::cmp::Ordering;
21 use std::marker::PhantomData;
23 use rustc_target::spec::abi;
24 use syntax::ast::{self, Ident};
25 use syntax::symbol::{kw, InternedString};
31 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
32 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
33 pub struct TypeAndMut<'tcx> {
35 pub mutbl: hir::Mutability,
38 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
39 RustcEncodable, RustcDecodable, Copy, HashStable)]
40 /// A "free" region `fr` can be interpreted as "some region
41 /// at least as big as the scope `fr.scope`".
42 pub struct FreeRegion {
44 pub bound_region: BoundRegion,
47 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
48 RustcEncodable, RustcDecodable, Copy, HashStable)]
49 pub enum BoundRegion {
50 /// An anonymous region parameter for a given fn (&T)
53 /// Named region parameters for functions (a in &'a T)
55 /// The `DefId` is needed to distinguish free regions in
56 /// the event of shadowing.
57 BrNamed(DefId, InternedString),
59 /// Anonymous region for the implicit env pointer parameter
65 pub fn is_named(&self) -> bool {
67 BoundRegion::BrNamed(..) => true,
72 /// When canonicalizing, we replace unbound inference variables and free
73 /// regions with anonymous late bound regions. This method asserts that
74 /// we have an anonymous late bound region, which hence may refer to
75 /// a canonical variable.
76 pub fn assert_bound_var(&self) -> BoundVar {
78 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
79 _ => bug!("bound region is not anonymous"),
84 /// N.B., if you change this, you'll probably want to change the corresponding
85 /// AST structure in `libsyntax/ast.rs` as well.
86 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
87 RustcEncodable, RustcDecodable, HashStable, Debug)]
88 pub enum TyKind<'tcx> {
89 /// The primitive boolean type. Written as `bool`.
92 /// The primitive character type; holds a Unicode scalar value
93 /// (a non-surrogate code point). Written as `char`.
96 /// A primitive signed integer type. For example, `i32`.
99 /// A primitive unsigned integer type. For example, `u32`.
102 /// A primitive floating-point type. For example, `f64`.
105 /// Structures, enumerations and unions.
107 /// InternalSubsts here, possibly against intuition, *may* contain `Param`s.
108 /// That is, even after substitution it is possible that there are type
109 /// variables. This happens when the `Adt` corresponds to an ADT
110 /// definition and not a concrete use of it.
111 Adt(&'tcx AdtDef, SubstsRef<'tcx>),
113 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
116 /// The pointee of a string slice. Written as `str`.
119 /// An array with the given length. Written as `[T; n]`.
120 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
122 /// The pointee of an array slice. Written as `[T]`.
125 /// A raw pointer. Written as `*mut T` or `*const T`
126 RawPtr(TypeAndMut<'tcx>),
128 /// A reference; a pointer with an associated lifetime. Written as
129 /// `&'a mut T` or `&'a T`.
130 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
132 /// The anonymous type of a function declaration/definition. Each
133 /// function has a unique type, which is output (for a function
134 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
136 /// For example the type of `bar` here:
139 /// fn foo() -> i32 { 1 }
140 /// let bar = foo; // bar: fn() -> i32 {foo}
142 FnDef(DefId, SubstsRef<'tcx>),
144 /// A pointer to a function. Written as `fn() -> i32`.
146 /// For example the type of `bar` here:
149 /// fn foo() -> i32 { 1 }
150 /// let bar: fn() -> i32 = foo;
152 FnPtr(PolyFnSig<'tcx>),
154 /// A trait, defined with `trait`.
155 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
157 /// The anonymous type of a closure. Used to represent the type of
159 Closure(DefId, ClosureSubsts<'tcx>),
161 /// The anonymous type of a generator. Used to represent the type of
163 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
165 /// A type representin the types stored inside a generator.
166 /// This should only appear in GeneratorInteriors.
167 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
169 /// The never type `!`
172 /// A tuple type. For example, `(i32, bool)`.
173 Tuple(SubstsRef<'tcx>),
175 /// The projection of an associated type. For example,
176 /// `<T as Trait<..>>::N`.
177 Projection(ProjectionTy<'tcx>),
179 /// A placeholder type used when we do not have enough information
180 /// to normalize the projection of an associated type to an
181 /// existing concrete type. Currently only used with chalk-engine.
182 UnnormalizedProjection(ProjectionTy<'tcx>),
184 /// Opaque (`impl Trait`) type found in a return type.
185 /// The `DefId` comes either from
186 /// * the `impl Trait` ast::Ty node,
187 /// * or the `existential type` declaration
188 /// The substitutions are for the generics of the function in question.
189 /// After typeck, the concrete type can be found in the `types` map.
190 Opaque(DefId, SubstsRef<'tcx>),
192 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
195 /// Bound type variable, used only when preparing a trait query.
196 Bound(ty::DebruijnIndex, BoundTy),
198 /// A placeholder type - universally quantified higher-ranked type.
199 Placeholder(ty::PlaceholderType),
201 /// A type variable used during type checking.
204 /// A placeholder for a type which could not be computed; this is
205 /// propagated to avoid useless error messages.
209 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
210 #[cfg(target_arch = "x86_64")]
211 static_assert_size!(TyKind<'_>, 24);
213 /// A closure can be modeled as a struct that looks like:
215 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
223 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
224 /// in scope on the function that defined the closure,
225 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
226 /// is rather hackily encoded via a scalar type. See
227 /// `TyS::to_opt_closure_kind` for details.
228 /// - CS represents the *closure signature*, representing as a `fn()`
229 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
230 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
232 /// - U0...Uk are type parameters representing the types of its upvars
233 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
234 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
236 /// So, for example, given this function:
238 /// fn foo<'a, T>(data: &'a mut T) {
239 /// do(|| data.count += 1)
242 /// the type of the closure would be something like:
244 /// struct Closure<'a, T, U0> {
248 /// Note that the type of the upvar is not specified in the struct.
249 /// You may wonder how the impl would then be able to use the upvar,
250 /// if it doesn't know it's type? The answer is that the impl is
251 /// (conceptually) not fully generic over Closure but rather tied to
252 /// instances with the expected upvar types:
254 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
258 /// You can see that the *impl* fully specified the type of the upvar
259 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
260 /// (Here, I am assuming that `data` is mut-borrowed.)
262 /// Now, the last question you may ask is: Why include the upvar types
263 /// as extra type parameters? The reason for this design is that the
264 /// upvar types can reference lifetimes that are internal to the
265 /// creating function. In my example above, for example, the lifetime
266 /// `'b` represents the scope of the closure itself; this is some
267 /// subset of `foo`, probably just the scope of the call to the to
268 /// `do()`. If we just had the lifetime/type parameters from the
269 /// enclosing function, we couldn't name this lifetime `'b`. Note that
270 /// there can also be lifetimes in the types of the upvars themselves,
271 /// if one of them happens to be a reference to something that the
272 /// creating fn owns.
274 /// OK, you say, so why not create a more minimal set of parameters
275 /// that just includes the extra lifetime parameters? The answer is
276 /// primarily that it would be hard --- we don't know at the time when
277 /// we create the closure type what the full types of the upvars are,
278 /// nor do we know which are borrowed and which are not. In this
279 /// design, we can just supply a fresh type parameter and figure that
282 /// All right, you say, but why include the type parameters from the
283 /// original function then? The answer is that codegen may need them
284 /// when monomorphizing, and they may not appear in the upvars. A
285 /// closure could capture no variables but still make use of some
286 /// in-scope type parameter with a bound (e.g., if our example above
287 /// had an extra `U: Default`, and the closure called `U::default()`).
289 /// There is another reason. This design (implicitly) prohibits
290 /// closures from capturing themselves (except via a trait
291 /// object). This simplifies closure inference considerably, since it
292 /// means that when we infer the kind of a closure or its upvars, we
293 /// don't have to handle cycles where the decisions we make for
294 /// closure C wind up influencing the decisions we ought to make for
295 /// closure C (which would then require fixed point iteration to
296 /// handle). Plus it fixes an ICE. :P
300 /// Generators are handled similarly in `GeneratorSubsts`. The set of
301 /// type parameters is similar, but the role of CK and CS are
302 /// different. CK represents the "yield type" and CS represents the
303 /// "return type" of the generator.
304 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
305 Debug, RustcEncodable, RustcDecodable, HashStable)]
306 pub struct ClosureSubsts<'tcx> {
307 /// Lifetime and type parameters from the enclosing function,
308 /// concatenated with the types of the upvars.
310 /// These are separated out because codegen wants to pass them around
311 /// when monomorphizing.
312 pub substs: SubstsRef<'tcx>,
315 /// Struct returned by `split()`. Note that these are subslices of the
316 /// parent slice and not canonical substs themselves.
317 struct SplitClosureSubsts<'tcx> {
318 closure_kind_ty: Ty<'tcx>,
319 closure_sig_ty: Ty<'tcx>,
320 upvar_kinds: &'tcx [Kind<'tcx>],
323 impl<'tcx> ClosureSubsts<'tcx> {
324 /// Divides the closure substs into their respective
325 /// components. Single source of truth with respect to the
327 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
328 let generics = tcx.generics_of(def_id);
329 let parent_len = generics.parent_count;
331 closure_kind_ty: self.substs.type_at(parent_len),
332 closure_sig_ty: self.substs.type_at(parent_len + 1),
333 upvar_kinds: &self.substs[parent_len + 2..],
338 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
339 impl Iterator<Item=Ty<'tcx>> + 'tcx
341 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
342 upvar_kinds.iter().map(|t| {
343 if let UnpackedKind::Type(ty) = t.unpack() {
346 bug!("upvar should be type")
351 /// Returns the closure kind for this closure; may return a type
352 /// variable during inference. To get the closure kind during
353 /// inference, use `infcx.closure_kind(def_id, substs)`.
354 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
355 self.split(def_id, tcx).closure_kind_ty
358 /// Returns the type representing the closure signature for this
359 /// closure; may contain type variables during inference. To get
360 /// the closure signature during inference, use
361 /// `infcx.fn_sig(def_id)`.
362 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
363 self.split(def_id, tcx).closure_sig_ty
366 /// Returns the closure kind for this closure; only usable outside
367 /// of an inference context, because in that context we know that
368 /// there are no type variables.
370 /// If you have an inference context, use `infcx.closure_kind()`.
371 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'tcx, 'tcx, 'tcx>) -> ty::ClosureKind {
372 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
375 /// Extracts the signature from the 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_sig()`.
380 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'tcx, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
381 let ty = self.closure_sig_ty(def_id, tcx);
383 ty::FnPtr(sig) => sig,
384 _ => bug!("closure_sig_ty is not a fn-ptr: {:?}", ty),
389 /// Similar to `ClosureSubsts`; see the above documentation for more.
390 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug,
391 RustcEncodable, RustcDecodable, HashStable)]
392 pub struct GeneratorSubsts<'tcx> {
393 pub substs: SubstsRef<'tcx>,
396 struct SplitGeneratorSubsts<'tcx> {
400 upvar_kinds: &'tcx [Kind<'tcx>],
403 impl<'tcx> GeneratorSubsts<'tcx> {
404 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
405 let generics = tcx.generics_of(def_id);
406 let parent_len = generics.parent_count;
407 SplitGeneratorSubsts {
408 yield_ty: self.substs.type_at(parent_len),
409 return_ty: self.substs.type_at(parent_len + 1),
410 witness: self.substs.type_at(parent_len + 2),
411 upvar_kinds: &self.substs[parent_len + 3..],
415 /// This describes the types that can be contained in a generator.
416 /// It will be a type variable initially and unified in the last stages of typeck of a body.
417 /// It contains a tuple of all the types that could end up on a generator frame.
418 /// The state transformation MIR pass may only produce layouts which mention types
419 /// in this tuple. Upvars are not counted here.
420 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
421 self.split(def_id, tcx).witness
425 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
426 impl Iterator<Item=Ty<'tcx>> + 'tcx
428 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
429 upvar_kinds.iter().map(|t| {
430 if let UnpackedKind::Type(ty) = t.unpack() {
433 bug!("upvar should be type")
438 /// Returns the type representing the yield type of the generator.
439 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
440 self.split(def_id, tcx).yield_ty
443 /// Returns the type representing the return type of the generator.
444 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
445 self.split(def_id, tcx).return_ty
448 /// Returns the "generator signature", which consists of its yield
449 /// and return types.
451 /// N.B., some bits of the code prefers to see this wrapped in a
452 /// binder, but it never contains bound regions. Probably this
453 /// function should be removed.
454 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
455 ty::Binder::dummy(self.sig(def_id, tcx))
458 /// Returns the "generator signature", which consists of its yield
459 /// and return types.
460 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
462 yield_ty: self.yield_ty(def_id, tcx),
463 return_ty: self.return_ty(def_id, tcx),
468 impl<'gcx, 'tcx> GeneratorSubsts<'tcx> {
469 /// Generator have not been resumed yet
470 pub const UNRESUMED: usize = 0;
471 /// Generator has returned / is completed
472 pub const RETURNED: usize = 1;
473 /// Generator has been poisoned
474 pub const POISONED: usize = 2;
476 const UNRESUMED_NAME: &'static str = "Unresumed";
477 const RETURNED_NAME: &'static str = "Returned";
478 const POISONED_NAME: &'static str = "Panicked";
480 /// The valid variant indices of this Generator.
482 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Range<VariantIdx> {
483 // FIXME requires optimized MIR
484 let num_variants = tcx.generator_layout(def_id).variant_fields.len();
485 (VariantIdx::new(0)..VariantIdx::new(num_variants))
488 /// The discriminant for the given variant. Panics if the variant_index is
491 pub fn discriminant_for_variant(
492 &self, def_id: DefId, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, variant_index: VariantIdx
494 // Generators don't support explicit discriminant values, so they are
495 // the same as the variant index.
496 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
497 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
500 /// The set of all discriminants for the Generator, enumerated with their
503 pub fn discriminants(
504 &'tcx self, def_id: DefId, tcx: TyCtxt<'tcx, 'gcx, 'tcx>
505 ) -> impl Iterator<Item=(VariantIdx, Discr<'tcx>)> + Captures<'gcx> {
506 self.variant_range(def_id, tcx).map(move |index| {
507 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
511 /// Calls `f` with a reference to the name of the enumerator for the given
514 pub fn variant_name(&self, v: VariantIdx) -> Cow<'static, str> {
516 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
517 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
518 Self::POISONED => Cow::from(Self::POISONED_NAME),
519 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3))
523 /// The type of the state discriminant used in the generator type.
525 pub fn discr_ty(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Ty<'tcx> {
529 /// This returns the types of the MIR locals which had to be stored across suspension points.
530 /// It is calculated in rustc_mir::transform::generator::StateTransform.
531 /// All the types here must be in the tuple in GeneratorInterior.
533 /// The locals are grouped by their variant number. Note that some locals may
534 /// be repeated in multiple variants.
536 pub fn state_tys(self, def_id: DefId, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) ->
537 impl Iterator<Item=impl Iterator<Item=Ty<'tcx>> + Captures<'gcx>>
539 let layout = tcx.generator_layout(def_id);
540 layout.variant_fields.iter().map(move |variant| {
541 variant.iter().map(move |field| {
542 layout.field_tys[*field].subst(tcx, self.substs)
547 /// This is the types of the fields of a generator which are not stored in a
550 pub fn prefix_tys(self, def_id: DefId, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) ->
551 impl Iterator<Item=Ty<'tcx>>
553 self.upvar_tys(def_id, tcx)
557 #[derive(Debug, Copy, Clone)]
558 pub enum UpvarSubsts<'tcx> {
559 Closure(ClosureSubsts<'tcx>),
560 Generator(GeneratorSubsts<'tcx>),
563 impl<'tcx> UpvarSubsts<'tcx> {
565 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
566 impl Iterator<Item=Ty<'tcx>> + 'tcx
568 let upvar_kinds = match self {
569 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
570 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
572 upvar_kinds.iter().map(|t| {
573 if let UnpackedKind::Type(ty) = t.unpack() {
576 bug!("upvar should be type")
582 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash,
583 RustcEncodable, RustcDecodable, HashStable)]
584 pub enum ExistentialPredicate<'tcx> {
585 /// E.g., `Iterator`.
586 Trait(ExistentialTraitRef<'tcx>),
587 /// E.g., `Iterator::Item = T`.
588 Projection(ExistentialProjection<'tcx>),
593 impl<'gcx, 'tcx> ExistentialPredicate<'tcx> {
594 /// Compares via an ordering that will not change if modules are reordered or other changes are
595 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
596 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, other: &Self) -> Ordering {
597 use self::ExistentialPredicate::*;
598 match (*self, *other) {
599 (Trait(_), Trait(_)) => Ordering::Equal,
600 (Projection(ref a), Projection(ref b)) =>
601 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
602 (AutoTrait(ref a), AutoTrait(ref b)) =>
603 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
604 (Trait(_), _) => Ordering::Less,
605 (Projection(_), Trait(_)) => Ordering::Greater,
606 (Projection(_), _) => Ordering::Less,
607 (AutoTrait(_), _) => Ordering::Greater,
613 impl<'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
614 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
615 -> ty::Predicate<'tcx> {
616 use crate::ty::ToPredicate;
617 match *self.skip_binder() {
618 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
619 ExistentialPredicate::Projection(p) =>
620 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
621 ExistentialPredicate::AutoTrait(did) => {
622 let trait_ref = Binder(ty::TraitRef {
624 substs: tcx.mk_substs_trait(self_ty, &[]),
626 trait_ref.to_predicate()
632 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
634 impl<'tcx> List<ExistentialPredicate<'tcx>> {
635 /// Returns the "principal def id" of this set of existential predicates.
637 /// A Rust trait object type consists (in addition to a lifetime bound)
638 /// of a set of trait bounds, which are separated into any number
639 /// of auto-trait bounds, and at most 1 non-auto-trait bound. The
640 /// non-auto-trait bound is called the "principal" of the trait
643 /// Only the principal can have methods or type parameters (because
644 /// auto traits can have neither of them). This is important, because
645 /// it means the auto traits can be treated as an unordered set (methods
646 /// would force an order for the vtable, while relating traits with
647 /// type parameters without knowing the order to relate them in is
648 /// a rather non-trivial task).
650 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
651 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
652 /// are the set `{Sync}`.
654 /// It is also possible to have a "trivial" trait object that
655 /// consists only of auto traits, with no principal - for example,
656 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
657 /// is `{Send, Sync}`, while there is no principal. These trait objects
658 /// have a "trivial" vtable consisting of just the size, alignment,
660 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
662 ExistentialPredicate::Trait(tr) => Some(tr),
667 pub fn principal_def_id(&self) -> Option<DefId> {
668 self.principal().map(|d| d.def_id)
672 pub fn projection_bounds<'a>(&'a self) ->
673 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
674 self.iter().filter_map(|predicate| {
676 ExistentialPredicate::Projection(p) => Some(p),
683 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
684 self.iter().filter_map(|predicate| {
686 ExistentialPredicate::AutoTrait(d) => Some(d),
693 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
694 pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> {
695 self.skip_binder().principal().map(Binder::bind)
698 pub fn principal_def_id(&self) -> Option<DefId> {
699 self.skip_binder().principal_def_id()
703 pub fn projection_bounds<'a>(&'a self) ->
704 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
705 self.skip_binder().projection_bounds().map(Binder::bind)
709 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
710 self.skip_binder().auto_traits()
713 pub fn iter<'a>(&'a self)
714 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
715 self.skip_binder().iter().cloned().map(Binder::bind)
719 /// A complete reference to a trait. These take numerous guises in syntax,
720 /// but perhaps the most recognizable form is in a where-clause:
724 /// This would be represented by a trait-reference where the `DefId` is the
725 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
726 /// and `U` as parameter 1.
728 /// Trait references also appear in object types like `Foo<U>`, but in
729 /// that case the `Self` parameter is absent from the substitutions.
731 /// Note that a `TraitRef` introduces a level of region binding, to
732 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
733 /// or higher-ranked object types.
734 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
735 pub struct TraitRef<'tcx> {
737 pub substs: SubstsRef<'tcx>,
740 impl<'tcx> TraitRef<'tcx> {
741 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
742 TraitRef { def_id: def_id, substs: substs }
745 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
746 /// are the parameters defined on trait.
747 pub fn identity<'gcx>(tcx: TyCtxt<'tcx, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
750 substs: InternalSubsts::identity_for_item(tcx, def_id),
755 pub fn self_ty(&self) -> Ty<'tcx> {
756 self.substs.type_at(0)
759 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
760 // Select only the "input types" from a trait-reference. For
761 // now this is all the types that appear in the
762 // trait-reference, but it should eventually exclude
767 pub fn from_method(tcx: TyCtxt<'tcx, '_, 'tcx>,
769 substs: SubstsRef<'tcx>)
770 -> ty::TraitRef<'tcx> {
771 let defs = tcx.generics_of(trait_id);
775 substs: tcx.intern_substs(&substs[..defs.params.len()])
780 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
782 impl<'tcx> PolyTraitRef<'tcx> {
783 pub fn self_ty(&self) -> Ty<'tcx> {
784 self.skip_binder().self_ty()
787 pub fn def_id(&self) -> DefId {
788 self.skip_binder().def_id
791 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
792 // Note that we preserve binding levels
793 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
797 /// An existential reference to a trait, where `Self` is erased.
798 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
800 /// exists T. T: Trait<'a, 'b, X, Y>
802 /// The substitutions don't include the erased `Self`, only trait
803 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
804 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
805 RustcEncodable, RustcDecodable, HashStable)]
806 pub struct ExistentialTraitRef<'tcx> {
808 pub substs: SubstsRef<'tcx>,
811 impl<'gcx, 'tcx> ExistentialTraitRef<'tcx> {
812 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
813 // Select only the "input types" from a trait-reference. For
814 // now this is all the types that appear in the
815 // trait-reference, but it should eventually exclude
820 pub fn erase_self_ty(tcx: TyCtxt<'tcx, 'gcx, 'tcx>,
821 trait_ref: ty::TraitRef<'tcx>)
822 -> ty::ExistentialTraitRef<'tcx> {
823 // Assert there is a Self.
824 trait_ref.substs.type_at(0);
826 ty::ExistentialTraitRef {
827 def_id: trait_ref.def_id,
828 substs: tcx.intern_substs(&trait_ref.substs[1..])
832 /// Object types don't have a self type specified. Therefore, when
833 /// we convert the principal trait-ref into a normal trait-ref,
834 /// you must give *some* self type. A common choice is `mk_err()`
835 /// or some placeholder type.
836 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
837 -> ty::TraitRef<'tcx> {
838 // otherwise the escaping vars would be captured by the binder
839 // debug_assert!(!self_ty.has_escaping_bound_vars());
843 substs: tcx.mk_substs_trait(self_ty, self.substs)
848 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
850 impl<'tcx> PolyExistentialTraitRef<'tcx> {
851 pub fn def_id(&self) -> DefId {
852 self.skip_binder().def_id
855 /// Object types don't have a self type specified. Therefore, when
856 /// we convert the principal trait-ref into a normal trait-ref,
857 /// you must give *some* self type. A common choice is `mk_err()`
858 /// or some placeholder type.
859 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx, '_, 'tcx>,
861 -> ty::PolyTraitRef<'tcx> {
862 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
866 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
867 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
868 /// (which would be represented by the type `PolyTraitRef ==
869 /// Binder<TraitRef>`). Note that when we instantiate,
870 /// erase, or otherwise "discharge" these bound vars, we change the
871 /// type from `Binder<T>` to just `T` (see
872 /// e.g., `liberate_late_bound_regions`).
873 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
874 pub struct Binder<T>(T);
877 /// Wraps `value` in a binder, asserting that `value` does not
878 /// contain any bound vars that would be bound by the
879 /// binder. This is commonly used to 'inject' a value T into a
880 /// different binding level.
881 pub fn dummy<'tcx>(value: T) -> Binder<T>
882 where T: TypeFoldable<'tcx>
884 debug_assert!(!value.has_escaping_bound_vars());
888 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
889 pub fn bind(value: T) -> Binder<T> {
893 /// Skips the binder and returns the "bound" value. This is a
894 /// risky thing to do because it's easy to get confused about
895 /// De Bruijn indices and the like. It is usually better to
896 /// discharge the binder using `no_bound_vars` or
897 /// `replace_late_bound_regions` or something like
898 /// that. `skip_binder` is only valid when you are either
899 /// extracting data that has nothing to do with bound vars, you
900 /// are doing some sort of test that does not involve bound
901 /// regions, or you are being very careful about your depth
904 /// Some examples where `skip_binder` is reasonable:
906 /// - extracting the `DefId` from a PolyTraitRef;
907 /// - comparing the self type of a PolyTraitRef to see if it is equal to
908 /// a type parameter `X`, since the type `X` does not reference any regions
909 pub fn skip_binder(&self) -> &T {
913 pub fn as_ref(&self) -> Binder<&T> {
917 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
918 where F: FnOnce(&T) -> U
920 self.as_ref().map_bound(f)
923 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
924 where F: FnOnce(T) -> U
929 /// Unwraps and returns the value within, but only if it contains
930 /// no bound vars at all. (In other words, if this binder --
931 /// and indeed any enclosing binder -- doesn't bind anything at
932 /// all.) Otherwise, returns `None`.
934 /// (One could imagine having a method that just unwraps a single
935 /// binder, but permits late-bound vars bound by enclosing
936 /// binders, but that would require adjusting the debruijn
937 /// indices, and given the shallow binding structure we often use,
938 /// would not be that useful.)
939 pub fn no_bound_vars<'tcx>(self) -> Option<T>
940 where T: TypeFoldable<'tcx>
942 if self.skip_binder().has_escaping_bound_vars() {
945 Some(self.skip_binder().clone())
949 /// Given two things that have the same binder level,
950 /// and an operation that wraps on their contents, executes the operation
951 /// and then wraps its result.
953 /// `f` should consider bound regions at depth 1 to be free, and
954 /// anything it produces with bound regions at depth 1 will be
955 /// bound in the resulting return value.
956 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
957 where F: FnOnce(T, U) -> R
959 Binder(f(self.0, u.0))
962 /// Splits the contents into two things that share the same binder
963 /// level as the original, returning two distinct binders.
965 /// `f` should consider bound regions at depth 1 to be free, and
966 /// anything it produces with bound regions at depth 1 will be
967 /// bound in the resulting return values.
968 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
969 where F: FnOnce(T) -> (U, V)
971 let (u, v) = f(self.0);
972 (Binder(u), Binder(v))
976 /// Represents the projection of an associated type. In explicit UFCS
977 /// form this would be written `<T as Trait<..>>::N`.
978 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
979 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
980 pub struct ProjectionTy<'tcx> {
981 /// The parameters of the associated item.
982 pub substs: SubstsRef<'tcx>,
984 /// The `DefId` of the `TraitItem` for the associated type `N`.
986 /// Note that this is not the `DefId` of the `TraitRef` containing this
987 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
988 pub item_def_id: DefId,
991 impl<'tcx> ProjectionTy<'tcx> {
992 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
993 /// associated item named `item_name`.
994 pub fn from_ref_and_name(
995 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
996 ) -> ProjectionTy<'tcx> {
997 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
998 item.kind == ty::AssocKind::Type &&
999 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
1003 substs: trait_ref.substs,
1008 /// Extracts the underlying trait reference from this projection.
1009 /// For example, if this is a projection of `<T as Iterator>::Item`,
1010 /// then this function would return a `T: Iterator` trait reference.
1011 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
1012 let def_id = tcx.associated_item(self.item_def_id).container.id();
1015 substs: self.substs,
1019 pub fn self_ty(&self) -> Ty<'tcx> {
1020 self.substs.type_at(0)
1024 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1025 pub struct GenSig<'tcx> {
1026 pub yield_ty: Ty<'tcx>,
1027 pub return_ty: Ty<'tcx>,
1030 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
1032 impl<'tcx> PolyGenSig<'tcx> {
1033 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
1034 self.map_bound_ref(|sig| sig.yield_ty)
1036 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
1037 self.map_bound_ref(|sig| sig.return_ty)
1041 /// Signature of a function type, which I have arbitrarily
1042 /// decided to use to refer to the input/output types.
1044 /// - `inputs`: is the list of arguments and their modes.
1045 /// - `output`: is the return type.
1046 /// - `c_variadic`: indicates whether this is a C-variadic function.
1047 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
1048 Hash, RustcEncodable, RustcDecodable, HashStable)]
1049 pub struct FnSig<'tcx> {
1050 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1051 pub c_variadic: bool,
1052 pub unsafety: hir::Unsafety,
1056 impl<'tcx> FnSig<'tcx> {
1057 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1058 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1061 pub fn output(&self) -> Ty<'tcx> {
1062 self.inputs_and_output[self.inputs_and_output.len() - 1]
1065 // Create a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible method
1066 fn fake() -> FnSig<'tcx> {
1068 inputs_and_output: List::empty(),
1070 unsafety: hir::Unsafety::Normal,
1071 abi: abi::Abi::Rust,
1076 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
1078 impl<'tcx> PolyFnSig<'tcx> {
1080 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
1081 self.map_bound_ref(|fn_sig| fn_sig.inputs())
1084 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
1085 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1087 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
1088 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1091 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
1092 self.map_bound_ref(|fn_sig| fn_sig.output())
1094 pub fn c_variadic(&self) -> bool {
1095 self.skip_binder().c_variadic
1097 pub fn unsafety(&self) -> hir::Unsafety {
1098 self.skip_binder().unsafety
1100 pub fn abi(&self) -> abi::Abi {
1101 self.skip_binder().abi
1105 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1108 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1109 Hash, RustcEncodable, RustcDecodable, HashStable)]
1110 pub struct ParamTy {
1112 pub name: InternedString,
1115 impl<'gcx, 'tcx> ParamTy {
1116 pub fn new(index: u32, name: InternedString) -> ParamTy {
1117 ParamTy { index, name: name }
1120 pub fn for_self() -> ParamTy {
1121 ParamTy::new(0, kw::SelfUpper.as_interned_str())
1124 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1125 ParamTy::new(def.index, def.name)
1128 pub fn to_ty(self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Ty<'tcx> {
1129 tcx.mk_ty_param(self.index, self.name)
1132 pub fn is_self(&self) -> bool {
1133 // FIXME(#50125): Ignoring `Self` with `index != 0` might lead to weird behavior elsewhere,
1134 // but this should only be possible when using `-Z continue-parse-after-error` like
1135 // `compile-fail/issue-36638.rs`.
1136 self.name.as_symbol() == kw::SelfUpper && self.index == 0
1140 #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable,
1141 Eq, PartialEq, Ord, PartialOrd, HashStable)]
1142 pub struct ParamConst {
1144 pub name: InternedString,
1147 impl<'gcx, 'tcx> ParamConst {
1148 pub fn new(index: u32, name: InternedString) -> ParamConst {
1149 ParamConst { index, name }
1152 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1153 ParamConst::new(def.index, def.name)
1156 pub fn to_const(self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
1157 tcx.mk_const_param(self.index, self.name, ty)
1162 /// A [De Bruijn index][dbi] is a standard means of representing
1163 /// regions (and perhaps later types) in a higher-ranked setting. In
1164 /// particular, imagine a type like this:
1166 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1169 /// | +------------+ 0 | |
1171 /// +--------------------------------+ 1 |
1173 /// +------------------------------------------+ 0
1175 /// In this type, there are two binders (the outer fn and the inner
1176 /// fn). We need to be able to determine, for any given region, which
1177 /// fn type it is bound by, the inner or the outer one. There are
1178 /// various ways you can do this, but a De Bruijn index is one of the
1179 /// more convenient and has some nice properties. The basic idea is to
1180 /// count the number of binders, inside out. Some examples should help
1181 /// clarify what I mean.
1183 /// Let's start with the reference type `&'b isize` that is the first
1184 /// argument to the inner function. This region `'b` is assigned a De
1185 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1186 /// fn). The region `'a` that appears in the second argument type (`&'a
1187 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1188 /// second-innermost binder". (These indices are written on the arrays
1189 /// in the diagram).
1191 /// What is interesting is that De Bruijn index attached to a particular
1192 /// variable will vary depending on where it appears. For example,
1193 /// the final type `&'a char` also refers to the region `'a` declared on
1194 /// the outermost fn. But this time, this reference is not nested within
1195 /// any other binders (i.e., it is not an argument to the inner fn, but
1196 /// rather the outer one). Therefore, in this case, it is assigned a
1197 /// De Bruijn index of 0, because the innermost binder in that location
1198 /// is the outer fn.
1200 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1201 pub struct DebruijnIndex {
1202 DEBUG_FORMAT = "DebruijnIndex({})",
1203 const INNERMOST = 0,
1207 pub type Region<'tcx> = &'tcx RegionKind;
1209 /// Representation of regions.
1211 /// Unlike types, most region variants are "fictitious", not concrete,
1212 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1213 /// ones representing concrete regions.
1215 /// ## Bound Regions
1217 /// These are regions that are stored behind a binder and must be substituted
1218 /// with some concrete region before being used. There are two kind of
1219 /// bound regions: early-bound, which are bound in an item's `Generics`,
1220 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1221 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1222 /// the likes of `liberate_late_bound_regions`. The distinction exists
1223 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1225 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1226 /// outside their binder, e.g., in types passed to type inference, and
1227 /// should first be substituted (by placeholder regions, free regions,
1228 /// or region variables).
1230 /// ## Placeholder and Free Regions
1232 /// One often wants to work with bound regions without knowing their precise
1233 /// identity. For example, when checking a function, the lifetime of a borrow
1234 /// can end up being assigned to some region parameter. In these cases,
1235 /// it must be ensured that bounds on the region can't be accidentally
1236 /// assumed without being checked.
1238 /// To do this, we replace the bound regions with placeholder markers,
1239 /// which don't satisfy any relation not explicitly provided.
1241 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1242 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1243 /// to be used. These also support explicit bounds: both the internally-stored
1244 /// *scope*, which the region is assumed to outlive, as well as other
1245 /// relations stored in the `FreeRegionMap`. Note that these relations
1246 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1247 /// `resolve_regions_and_report_errors`.
1249 /// When working with higher-ranked types, some region relations aren't
1250 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1251 /// `RePlaceholder` is designed for this purpose. In these contexts,
1252 /// there's also the risk that some inference variable laying around will
1253 /// get unified with your placeholder region: if you want to check whether
1254 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1255 /// with a placeholder region `'%a`, the variable `'_` would just be
1256 /// instantiated to the placeholder region `'%a`, which is wrong because
1257 /// the inference variable is supposed to satisfy the relation
1258 /// *for every value of the placeholder region*. To ensure that doesn't
1259 /// happen, you can use `leak_check`. This is more clearly explained
1260 /// by the [rustc guide].
1262 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1263 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1264 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1265 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1266 pub enum RegionKind {
1267 /// Region bound in a type or fn declaration which will be
1268 /// substituted 'early' -- that is, at the same time when type
1269 /// parameters are substituted.
1270 ReEarlyBound(EarlyBoundRegion),
1272 /// Region bound in a function scope, which will be substituted when the
1273 /// function is called.
1274 ReLateBound(DebruijnIndex, BoundRegion),
1276 /// When checking a function body, the types of all arguments and so forth
1277 /// that refer to bound region parameters are modified to refer to free
1278 /// region parameters.
1281 /// A concrete region naming some statically determined scope
1282 /// (e.g., an expression or sequence of statements) within the
1283 /// current function.
1284 ReScope(region::Scope),
1286 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1289 /// A region variable. Should not exist after typeck.
1292 /// A placeholder region - basically the higher-ranked version of ReFree.
1293 /// Should not exist after typeck.
1294 RePlaceholder(ty::PlaceholderRegion),
1296 /// Empty lifetime is for data that is never accessed.
1297 /// Bottom in the region lattice. We treat ReEmpty somewhat
1298 /// specially; at least right now, we do not generate instances of
1299 /// it during the GLB computations, but rather
1300 /// generate an error instead. This is to improve error messages.
1301 /// The only way to get an instance of ReEmpty is to have a region
1302 /// variable with no constraints.
1305 /// Erased region, used by trait selection, in MIR and during codegen.
1308 /// These are regions bound in the "defining type" for a
1309 /// closure. They are used ONLY as part of the
1310 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1311 /// See `ClosureRegionRequirements` for more details.
1312 ReClosureBound(RegionVid),
1315 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1317 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1318 pub struct EarlyBoundRegion {
1321 pub name: InternedString,
1324 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1329 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1330 pub struct ConstVid<'tcx> {
1332 pub phantom: PhantomData<&'tcx ()>,
1335 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1340 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1341 pub struct FloatVid {
1346 pub struct RegionVid {
1347 DEBUG_FORMAT = custom,
1351 impl Atom for RegionVid {
1352 fn index(self) -> usize {
1357 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1358 Hash, RustcEncodable, RustcDecodable, HashStable)]
1364 /// A `FreshTy` is one that is generated as a replacement for an
1365 /// unbound type variable. This is convenient for caching etc. See
1366 /// `infer::freshen` for more details.
1373 pub struct BoundVar { .. }
1376 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1377 pub struct BoundTy {
1379 pub kind: BoundTyKind,
1382 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1383 pub enum BoundTyKind {
1385 Param(InternedString),
1388 impl_stable_hash_for!(struct BoundTy { var, kind });
1389 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1391 impl From<BoundVar> for BoundTy {
1392 fn from(var: BoundVar) -> Self {
1395 kind: BoundTyKind::Anon,
1400 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1401 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash,
1402 Debug, RustcEncodable, RustcDecodable, HashStable)]
1403 pub struct ExistentialProjection<'tcx> {
1404 pub item_def_id: DefId,
1405 pub substs: SubstsRef<'tcx>,
1409 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1411 impl<'tcx, 'gcx> ExistentialProjection<'tcx> {
1412 /// Extracts the underlying existential trait reference from this projection.
1413 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1414 /// then this function would return a `exists T. T: Iterator` existential trait
1416 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1417 let def_id = tcx.associated_item(self.item_def_id).container.id();
1418 ty::ExistentialTraitRef{
1420 substs: self.substs,
1424 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>,
1426 -> ty::ProjectionPredicate<'tcx>
1428 // otherwise the escaping regions would be captured by the binders
1429 debug_assert!(!self_ty.has_escaping_bound_vars());
1431 ty::ProjectionPredicate {
1432 projection_ty: ty::ProjectionTy {
1433 item_def_id: self.item_def_id,
1434 substs: tcx.mk_substs_trait(self_ty, self.substs),
1441 impl<'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1442 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1443 -> ty::PolyProjectionPredicate<'tcx> {
1444 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1447 pub fn item_def_id(&self) -> DefId {
1448 return self.skip_binder().item_def_id;
1452 impl DebruijnIndex {
1453 /// Returns the resulting index when this value is moved into
1454 /// `amount` number of new binders. So, e.g., if you had
1456 /// for<'a> fn(&'a x)
1458 /// and you wanted to change it to
1460 /// for<'a> fn(for<'b> fn(&'a x))
1462 /// you would need to shift the index for `'a` into a new binder.
1464 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1465 DebruijnIndex::from_u32(self.as_u32() + amount)
1468 /// Update this index in place by shifting it "in" through
1469 /// `amount` number of binders.
1470 pub fn shift_in(&mut self, amount: u32) {
1471 *self = self.shifted_in(amount);
1474 /// Returns the resulting index when this value is moved out from
1475 /// `amount` number of new binders.
1477 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1478 DebruijnIndex::from_u32(self.as_u32() - amount)
1481 /// Update in place by shifting out from `amount` binders.
1482 pub fn shift_out(&mut self, amount: u32) {
1483 *self = self.shifted_out(amount);
1486 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1487 /// innermost binder. That is, if we have something bound at `to_binder`,
1488 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1489 /// when moving a region out from inside binders:
1492 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1493 /// // Binder: D3 D2 D1 ^^
1496 /// Here, the region `'a` would have the De Bruijn index D3,
1497 /// because it is the bound 3 binders out. However, if we wanted
1498 /// to refer to that region `'a` in the second argument (the `_`),
1499 /// those two binders would not be in scope. In that case, we
1500 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1501 /// De Bruijn index of `'a` to D1 (the innermost binder).
1503 /// If we invoke `shift_out_to_binder` and the region is in fact
1504 /// bound by one of the binders we are shifting out of, that is an
1505 /// error (and should fail an assertion failure).
1506 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1507 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1511 impl_stable_hash_for!(struct DebruijnIndex { private });
1513 /// Region utilities
1515 /// Is this region named by the user?
1516 pub fn has_name(&self) -> bool {
1518 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1519 RegionKind::ReLateBound(_, br) => br.is_named(),
1520 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1521 RegionKind::ReScope(..) => false,
1522 RegionKind::ReStatic => true,
1523 RegionKind::ReVar(..) => false,
1524 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1525 RegionKind::ReEmpty => false,
1526 RegionKind::ReErased => false,
1527 RegionKind::ReClosureBound(..) => false,
1531 pub fn is_late_bound(&self) -> bool {
1533 ty::ReLateBound(..) => true,
1538 pub fn is_placeholder(&self) -> bool {
1540 ty::RePlaceholder(..) => true,
1545 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1547 ty::ReLateBound(debruijn, _) => debruijn >= index,
1552 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1553 /// innermost binder. That is, if we have something bound at `to_binder`,
1554 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1555 /// when moving a region out from inside binders:
1558 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1559 /// // Binder: D3 D2 D1 ^^
1562 /// Here, the region `'a` would have the De Bruijn index D3,
1563 /// because it is the bound 3 binders out. However, if we wanted
1564 /// to refer to that region `'a` in the second argument (the `_`),
1565 /// those two binders would not be in scope. In that case, we
1566 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1567 /// De Bruijn index of `'a` to D1 (the innermost binder).
1569 /// If we invoke `shift_out_to_binder` and the region is in fact
1570 /// bound by one of the binders we are shifting out of, that is an
1571 /// error (and should fail an assertion failure).
1572 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1574 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1575 debruijn.shifted_out_to_binder(to_binder),
1582 pub fn keep_in_local_tcx(&self) -> bool {
1583 if let ty::ReVar(..) = self {
1590 pub fn type_flags(&self) -> TypeFlags {
1591 let mut flags = TypeFlags::empty();
1593 if self.keep_in_local_tcx() {
1594 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1599 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1600 flags = flags | TypeFlags::HAS_RE_INFER;
1602 ty::RePlaceholder(..) => {
1603 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1604 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1606 ty::ReLateBound(..) => {
1607 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1609 ty::ReEarlyBound(..) => {
1610 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1611 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1616 ty::ReScope { .. } => {
1617 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1621 ty::ReClosureBound(..) => {
1622 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1627 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1628 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1631 debug!("type_flags({:?}) = {:?}", self, flags);
1636 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1637 /// For example, consider the regions in this snippet of code:
1641 /// ^^ -- early bound, declared on an impl
1643 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1644 /// ^^ ^^ ^ anonymous, late-bound
1645 /// | early-bound, appears in where-clauses
1646 /// late-bound, appears only in fn args
1651 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1652 /// of the impl, and for all the other highlighted regions, it
1653 /// would return the `DefId` of the function. In other cases (not shown), this
1654 /// function might return the `DefId` of a closure.
1655 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1657 ty::ReEarlyBound(br) => {
1658 tcx.parent(br.def_id).unwrap()
1660 ty::ReFree(fr) => fr.scope,
1661 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1667 impl<'gcx, 'tcx> TyS<'tcx> {
1669 pub fn is_unit(&self) -> bool {
1671 Tuple(ref tys) => tys.is_empty(),
1677 pub fn is_never(&self) -> bool {
1684 /// Checks whether a type is definitely uninhabited. This is
1685 /// conservative: for some types that are uninhabited we return `false`,
1686 /// but we only return `true` for types that are definitely uninhabited.
1687 /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
1688 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1689 /// size, to account for partial initialisation. See #49298 for details.)
1690 pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> bool {
1691 // FIXME(varkor): we can make this less conversative by substituting concrete
1695 ty::Adt(def, _) if def.is_union() => {
1696 // For now, `union`s are never considered uninhabited.
1699 ty::Adt(def, _) => {
1700 // Any ADT is uninhabited if either:
1701 // (a) It has no variants (i.e. an empty `enum`);
1702 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1703 // one uninhabited field.
1704 def.variants.iter().all(|var| {
1705 var.fields.iter().any(|field| {
1706 tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
1710 ty::Tuple(tys) => tys.iter().any(|ty| {
1711 ty.expect_ty().conservative_is_privately_uninhabited(tcx)
1713 ty::Array(ty, len) => {
1714 match len.assert_usize(tcx) {
1715 // If the array is definitely non-empty, it's uninhabited if
1716 // the type of its elements is uninhabited.
1717 Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
1722 // References to uninitialised memory is valid for any type, including
1723 // uninhabited types, in unsafe code, so we treat all references as
1732 pub fn is_primitive(&self) -> bool {
1734 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1740 pub fn is_ty_var(&self) -> bool {
1742 Infer(TyVar(_)) => true,
1748 pub fn is_ty_infer(&self) -> bool {
1756 pub fn is_phantom_data(&self) -> bool {
1757 if let Adt(def, _) = self.sty {
1758 def.is_phantom_data()
1765 pub fn is_bool(&self) -> bool { self.sty == Bool }
1768 pub fn is_param(&self, index: u32) -> bool {
1770 ty::Param(ref data) => data.index == index,
1776 pub fn is_self(&self) -> bool {
1778 Param(ref p) => p.is_self(),
1784 pub fn is_slice(&self) -> bool {
1786 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1787 Slice(_) | Str => true,
1795 pub fn is_simd(&self) -> bool {
1797 Adt(def, _) => def.repr.simd(),
1802 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Ty<'tcx> {
1804 Array(ty, _) | Slice(ty) => ty,
1805 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1806 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1810 pub fn simd_type(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Ty<'tcx> {
1812 Adt(def, substs) => {
1813 def.non_enum_variant().fields[0].ty(tcx, substs)
1815 _ => bug!("simd_type called on invalid type")
1819 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1821 Adt(def, _) => def.non_enum_variant().fields.len(),
1822 _ => bug!("simd_size called on invalid type")
1827 pub fn is_region_ptr(&self) -> bool {
1835 pub fn is_mutable_pointer(&self) -> bool {
1837 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1838 Ref(_, _, hir::Mutability::MutMutable) => true,
1844 pub fn is_unsafe_ptr(&self) -> bool {
1846 RawPtr(_) => return true,
1851 /// Returns `true` if this type is an `Arc<T>`.
1853 pub fn is_arc(&self) -> bool {
1855 Adt(def, _) => def.is_arc(),
1860 /// Returns `true` if this type is an `Rc<T>`.
1862 pub fn is_rc(&self) -> bool {
1864 Adt(def, _) => def.is_rc(),
1870 pub fn is_box(&self) -> bool {
1872 Adt(def, _) => def.is_box(),
1877 /// panics if called on any type other than `Box<T>`
1878 pub fn boxed_ty(&self) -> Ty<'tcx> {
1880 Adt(def, substs) if def.is_box() => substs.type_at(0),
1881 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1885 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1886 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1887 /// contents are abstract to rustc.)
1889 pub fn is_scalar(&self) -> bool {
1891 Bool | Char | Int(_) | Float(_) | Uint(_) |
1892 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1893 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1898 /// Returns `true` if this type is a floating point type.
1900 pub fn is_floating_point(&self) -> bool {
1903 Infer(FloatVar(_)) => true,
1909 pub fn is_trait(&self) -> bool {
1911 Dynamic(..) => true,
1917 pub fn is_enum(&self) -> bool {
1919 Adt(adt_def, _) => {
1927 pub fn is_closure(&self) -> bool {
1929 Closure(..) => true,
1935 pub fn is_generator(&self) -> bool {
1937 Generator(..) => true,
1943 pub fn is_integral(&self) -> bool {
1945 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1951 pub fn is_fresh_ty(&self) -> bool {
1953 Infer(FreshTy(_)) => true,
1959 pub fn is_fresh(&self) -> bool {
1961 Infer(FreshTy(_)) => true,
1962 Infer(FreshIntTy(_)) => true,
1963 Infer(FreshFloatTy(_)) => true,
1969 pub fn is_char(&self) -> bool {
1977 pub fn is_numeric(&self) -> bool {
1978 self.is_integral() || self.is_floating_point()
1982 pub fn is_signed(&self) -> bool {
1990 pub fn is_pointer_sized(&self) -> bool {
1992 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
1998 pub fn is_machine(&self) -> bool {
2000 Int(..) | Uint(..) | Float(..) => true,
2006 pub fn has_concrete_skeleton(&self) -> bool {
2008 Param(_) | Infer(_) | Error => false,
2013 /// Returns the type and mutability of `*ty`.
2015 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2016 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2017 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2019 Adt(def, _) if def.is_box() => {
2021 ty: self.boxed_ty(),
2022 mutbl: hir::MutImmutable,
2025 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
2026 RawPtr(mt) if explicit => Some(mt),
2031 /// Returns the type of `ty[i]`.
2032 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2034 Array(ty, _) | Slice(ty) => Some(ty),
2039 pub fn fn_sig(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
2041 FnDef(def_id, substs) => {
2042 tcx.fn_sig(def_id).subst(tcx, substs)
2045 Error => { // ignore errors (#54954)
2046 ty::Binder::dummy(FnSig::fake())
2048 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
2053 pub fn is_fn(&self) -> bool {
2055 FnDef(..) | FnPtr(_) => true,
2061 pub fn is_fn_ptr(&self) -> bool {
2069 pub fn is_impl_trait(&self) -> bool {
2077 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2079 Adt(adt, _) => Some(adt),
2084 /// If the type contains variants, returns the valid range of variant indices.
2085 /// FIXME This requires the optimized MIR in the case of generators.
2087 pub fn variant_range(&self, tcx: TyCtxt<'tcx, 'gcx, 'tcx>) -> Option<Range<VariantIdx>> {
2089 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2090 TyKind::Generator(def_id, substs, _) => Some(substs.variant_range(def_id, tcx)),
2095 /// If the type contains variants, returns the variant for `variant_index`.
2096 /// Panics if `variant_index` is out of range.
2097 /// FIXME This requires the optimized MIR in the case of generators.
2099 pub fn discriminant_for_variant(
2101 tcx: TyCtxt<'tcx, 'gcx, 'tcx>,
2102 variant_index: VariantIdx
2103 ) -> Option<Discr<'tcx>> {
2105 TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)),
2106 TyKind::Generator(def_id, substs, _) =>
2107 Some(substs.discriminant_for_variant(def_id, tcx, variant_index)),
2112 /// Push onto `out` the regions directly referenced from this type (but not
2113 /// types reachable from this type via `walk_tys`). This ignores late-bound
2114 /// regions binders.
2115 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
2117 Ref(region, _, _) => {
2120 Dynamic(ref obj, region) => {
2122 if let Some(principal) = obj.principal() {
2123 out.extend(principal.skip_binder().substs.regions());
2126 Adt(_, substs) | Opaque(_, substs) => {
2127 out.extend(substs.regions())
2129 Closure(_, ClosureSubsts { ref substs }) |
2130 Generator(_, GeneratorSubsts { ref substs }, _) => {
2131 out.extend(substs.regions())
2133 Projection(ref data) | UnnormalizedProjection(ref data) => {
2134 out.extend(data.substs.regions())
2138 GeneratorWitness(..) |
2159 /// When we create a closure, we record its kind (i.e., what trait
2160 /// it implements) into its `ClosureSubsts` using a type
2161 /// parameter. This is kind of a phantom type, except that the
2162 /// most convenient thing for us to are the integral types. This
2163 /// function converts such a special type into the closure
2164 /// kind. To go the other way, use
2165 /// `tcx.closure_kind_ty(closure_kind)`.
2167 /// Note that during type checking, we use an inference variable
2168 /// to represent the closure kind, because it has not yet been
2169 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2170 /// is complete, that type variable will be unified.
2171 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2173 Int(int_ty) => match int_ty {
2174 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
2175 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2176 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2177 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2182 Error => Some(ty::ClosureKind::Fn),
2184 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2188 /// Fast path helper for testing if a type is `Sized`.
2190 /// Returning true means the type is known to be sized. Returning
2191 /// `false` means nothing -- could be sized, might not be.
2192 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx, '_, 'tcx>) -> bool {
2194 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
2195 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
2196 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
2197 ty::Char | ty::Ref(..) | ty::Generator(..) |
2198 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
2199 ty::Never | ty::Error =>
2202 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2206 tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx))
2209 ty::Adt(def, _substs) =>
2210 def.sized_constraint(tcx).is_empty(),
2212 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2214 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2216 ty::Infer(ty::TyVar(_)) => false,
2219 ty::Placeholder(..) |
2220 ty::Infer(ty::FreshTy(_)) |
2221 ty::Infer(ty::FreshIntTy(_)) |
2222 ty::Infer(ty::FreshFloatTy(_)) =>
2223 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2228 /// Typed constant value.
2229 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable,
2230 Eq, PartialEq, Ord, PartialOrd, HashStable)]
2231 pub struct Const<'tcx> {
2234 pub val: ConstValue<'tcx>,
2237 #[cfg(target_arch = "x86_64")]
2238 static_assert_size!(Const<'_>, 40);
2240 impl<'tcx> Const<'tcx> {
2243 tcx: TyCtxt<'tcx, '_, 'tcx>,
2248 val: ConstValue::Scalar(val),
2255 tcx: TyCtxt<'tcx, '_, 'tcx>,
2257 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2259 let ty = tcx.lift_to_global(&ty).unwrap();
2260 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2261 panic!("could not compute layout for {:?}: {:?}", ty, e)
2263 Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
2267 pub fn zero_sized(tcx: TyCtxt<'tcx, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2268 Self::from_scalar(tcx, Scalar::zst(), ty)
2272 pub fn from_bool(tcx: TyCtxt<'tcx, '_, 'tcx>, v: bool) -> &'tcx Self {
2273 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2277 pub fn from_usize(tcx: TyCtxt<'tcx, '_, 'tcx>, n: u64) -> &'tcx Self {
2278 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2284 tcx: TyCtxt<'tcx, '_, 'tcx>,
2285 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2287 if self.ty != ty.value {
2290 let ty = tcx.lift_to_global(&ty).unwrap();
2291 let size = tcx.layout_of(ty).ok()?.size;
2292 self.val.try_to_bits(size)
2296 pub fn to_ptr(&self) -> Option<Pointer> {
2297 self.val.try_to_ptr()
2303 tcx: TyCtxt<'_, '_, '_>,
2304 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2306 assert_eq!(self.ty, ty.value);
2307 let ty = tcx.lift_to_global(&ty).unwrap();
2308 let size = tcx.layout_of(ty).ok()?.size;
2309 self.val.try_to_bits(size)
2313 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2314 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2322 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2323 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2329 tcx: TyCtxt<'_, '_, '_>,
2330 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2332 self.assert_bits(tcx, ty).unwrap_or_else(||
2333 bug!("expected bits of {}, got {:#?}", ty.value, self))
2337 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2338 self.assert_usize(tcx).unwrap_or_else(||
2339 bug!("expected constant usize, got {:#?}", self))
2343 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
2345 /// An inference variable for a const, for use in const generics.
2346 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd,
2347 Ord, RustcEncodable, RustcDecodable, Hash, HashStable)]
2348 pub enum InferConst<'tcx> {
2349 /// Infer the value of the const.
2350 Var(ConstVid<'tcx>),
2351 /// A fresh const variable. See `infer::freshen` for more details.
2353 /// Canonicalized const variable, used only when preparing a trait query.
2354 Canonical(DebruijnIndex, BoundVar),