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, truncate};
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 /// Fresh bound identifiers created during GLB computations.
62 /// Anonymous region for the implicit env pointer parameter
68 pub fn is_named(&self) -> bool {
70 BoundRegion::BrNamed(..) => true,
75 /// When canonicalizing, we replace unbound inference variables and free
76 /// regions with anonymous late bound regions. This method asserts that
77 /// we have an anonymous late bound region, which hence may refer to
78 /// a canonical variable.
79 pub fn assert_bound_var(&self) -> BoundVar {
81 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
82 _ => bug!("bound region is not anonymous"),
87 /// N.B., if you change this, you'll probably want to change the corresponding
88 /// AST structure in `libsyntax/ast.rs` as well.
89 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
90 RustcEncodable, RustcDecodable, HashStable, Debug)]
91 pub enum TyKind<'tcx> {
92 /// The primitive boolean type. Written as `bool`.
95 /// The primitive character type; holds a Unicode scalar value
96 /// (a non-surrogate code point). Written as `char`.
99 /// A primitive signed integer type. For example, `i32`.
102 /// A primitive unsigned integer type. For example, `u32`.
105 /// A primitive floating-point type. For example, `f64`.
108 /// Structures, enumerations and unions.
110 /// InternalSubsts here, possibly against intuition, *may* contain `Param`s.
111 /// That is, even after substitution it is possible that there are type
112 /// variables. This happens when the `Adt` corresponds to an ADT
113 /// definition and not a concrete use of it.
114 Adt(&'tcx AdtDef, SubstsRef<'tcx>),
116 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
119 /// The pointee of a string slice. Written as `str`.
122 /// An array with the given length. Written as `[T; n]`.
123 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
125 /// The pointee of an array slice. Written as `[T]`.
128 /// A raw pointer. Written as `*mut T` or `*const T`
129 RawPtr(TypeAndMut<'tcx>),
131 /// A reference; a pointer with an associated lifetime. Written as
132 /// `&'a mut T` or `&'a T`.
133 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
135 /// The anonymous type of a function declaration/definition. Each
136 /// function has a unique type, which is output (for a function
137 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
139 /// For example the type of `bar` here:
142 /// fn foo() -> i32 { 1 }
143 /// let bar = foo; // bar: fn() -> i32 {foo}
145 FnDef(DefId, SubstsRef<'tcx>),
147 /// A pointer to a function. Written as `fn() -> i32`.
149 /// For example the type of `bar` here:
152 /// fn foo() -> i32 { 1 }
153 /// let bar: fn() -> i32 = foo;
155 FnPtr(PolyFnSig<'tcx>),
157 /// A trait, defined with `trait`.
158 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
160 /// The anonymous type of a closure. Used to represent the type of
162 Closure(DefId, ClosureSubsts<'tcx>),
164 /// The anonymous type of a generator. Used to represent the type of
166 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
168 /// A type representin the types stored inside a generator.
169 /// This should only appear in GeneratorInteriors.
170 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
172 /// The never type `!`
175 /// A tuple type. For example, `(i32, bool)`.
176 Tuple(SubstsRef<'tcx>),
178 /// The projection of an associated type. For example,
179 /// `<T as Trait<..>>::N`.
180 Projection(ProjectionTy<'tcx>),
182 /// A placeholder type used when we do not have enough information
183 /// to normalize the projection of an associated type to an
184 /// existing concrete type. Currently only used with chalk-engine.
185 UnnormalizedProjection(ProjectionTy<'tcx>),
187 /// Opaque (`impl Trait`) type found in a return type.
188 /// The `DefId` comes either from
189 /// * the `impl Trait` ast::Ty node,
190 /// * or the `existential type` declaration
191 /// The substitutions are for the generics of the function in question.
192 /// After typeck, the concrete type can be found in the `types` map.
193 Opaque(DefId, SubstsRef<'tcx>),
195 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
198 /// Bound type variable, used only when preparing a trait query.
199 Bound(ty::DebruijnIndex, BoundTy),
201 /// A placeholder type - universally quantified higher-ranked type.
202 Placeholder(ty::PlaceholderType),
204 /// A type variable used during type checking.
207 /// A placeholder for a type which could not be computed; this is
208 /// propagated to avoid useless error messages.
212 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
213 #[cfg(target_arch = "x86_64")]
214 static_assert_size!(TyKind<'_>, 24);
216 /// A closure can be modeled as a struct that looks like:
218 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
226 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
227 /// in scope on the function that defined the closure,
228 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
229 /// is rather hackily encoded via a scalar type. See
230 /// `TyS::to_opt_closure_kind` for details.
231 /// - CS represents the *closure signature*, representing as a `fn()`
232 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
233 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
235 /// - U0...Uk are type parameters representing the types of its upvars
236 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
237 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
239 /// So, for example, given this function:
241 /// fn foo<'a, T>(data: &'a mut T) {
242 /// do(|| data.count += 1)
245 /// the type of the closure would be something like:
247 /// struct Closure<'a, T, U0> {
251 /// Note that the type of the upvar is not specified in the struct.
252 /// You may wonder how the impl would then be able to use the upvar,
253 /// if it doesn't know it's type? The answer is that the impl is
254 /// (conceptually) not fully generic over Closure but rather tied to
255 /// instances with the expected upvar types:
257 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
261 /// You can see that the *impl* fully specified the type of the upvar
262 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
263 /// (Here, I am assuming that `data` is mut-borrowed.)
265 /// Now, the last question you may ask is: Why include the upvar types
266 /// as extra type parameters? The reason for this design is that the
267 /// upvar types can reference lifetimes that are internal to the
268 /// creating function. In my example above, for example, the lifetime
269 /// `'b` represents the scope of the closure itself; this is some
270 /// subset of `foo`, probably just the scope of the call to the to
271 /// `do()`. If we just had the lifetime/type parameters from the
272 /// enclosing function, we couldn't name this lifetime `'b`. Note that
273 /// there can also be lifetimes in the types of the upvars themselves,
274 /// if one of them happens to be a reference to something that the
275 /// creating fn owns.
277 /// OK, you say, so why not create a more minimal set of parameters
278 /// that just includes the extra lifetime parameters? The answer is
279 /// primarily that it would be hard --- we don't know at the time when
280 /// we create the closure type what the full types of the upvars are,
281 /// nor do we know which are borrowed and which are not. In this
282 /// design, we can just supply a fresh type parameter and figure that
285 /// All right, you say, but why include the type parameters from the
286 /// original function then? The answer is that codegen may need them
287 /// when monomorphizing, and they may not appear in the upvars. A
288 /// closure could capture no variables but still make use of some
289 /// in-scope type parameter with a bound (e.g., if our example above
290 /// had an extra `U: Default`, and the closure called `U::default()`).
292 /// There is another reason. This design (implicitly) prohibits
293 /// closures from capturing themselves (except via a trait
294 /// object). This simplifies closure inference considerably, since it
295 /// means that when we infer the kind of a closure or its upvars, we
296 /// don't have to handle cycles where the decisions we make for
297 /// closure C wind up influencing the decisions we ought to make for
298 /// closure C (which would then require fixed point iteration to
299 /// handle). Plus it fixes an ICE. :P
303 /// Generators are handled similarly in `GeneratorSubsts`. The set of
304 /// type parameters is similar, but the role of CK and CS are
305 /// different. CK represents the "yield type" and CS represents the
306 /// "return type" of the generator.
307 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
308 Debug, RustcEncodable, RustcDecodable, HashStable)]
309 pub struct ClosureSubsts<'tcx> {
310 /// Lifetime and type parameters from the enclosing function,
311 /// concatenated with the types of the upvars.
313 /// These are separated out because codegen wants to pass them around
314 /// when monomorphizing.
315 pub substs: SubstsRef<'tcx>,
318 /// Struct returned by `split()`. Note that these are subslices of the
319 /// parent slice and not canonical substs themselves.
320 struct SplitClosureSubsts<'tcx> {
321 closure_kind_ty: Ty<'tcx>,
322 closure_sig_ty: Ty<'tcx>,
323 upvar_kinds: &'tcx [Kind<'tcx>],
326 impl<'tcx> ClosureSubsts<'tcx> {
327 /// Divides the closure substs into their respective
328 /// components. Single source of truth with respect to the
330 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
331 let generics = tcx.generics_of(def_id);
332 let parent_len = generics.parent_count;
334 closure_kind_ty: self.substs.type_at(parent_len),
335 closure_sig_ty: self.substs.type_at(parent_len + 1),
336 upvar_kinds: &self.substs[parent_len + 2..],
341 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
342 impl Iterator<Item=Ty<'tcx>> + 'tcx
344 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
345 upvar_kinds.iter().map(|t| {
346 if let UnpackedKind::Type(ty) = t.unpack() {
349 bug!("upvar should be type")
354 /// Returns the closure kind for this closure; may return a type
355 /// variable during inference. To get the closure kind during
356 /// inference, use `infcx.closure_kind(def_id, substs)`.
357 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
358 self.split(def_id, tcx).closure_kind_ty
361 /// Returns the type representing the closure signature for this
362 /// closure; may contain type variables during inference. To get
363 /// the closure signature during inference, use
364 /// `infcx.fn_sig(def_id)`.
365 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
366 self.split(def_id, tcx).closure_sig_ty
369 /// Returns the closure kind for this closure; only usable outside
370 /// of an inference context, because in that context we know that
371 /// there are no type variables.
373 /// If you have an inference context, use `infcx.closure_kind()`.
374 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
375 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
378 /// Extracts the signature from the closure; only usable outside
379 /// of an inference context, because in that context we know that
380 /// there are no type variables.
382 /// If you have an inference context, use `infcx.closure_sig()`.
383 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
384 let ty = self.closure_sig_ty(def_id, tcx);
386 ty::FnPtr(sig) => sig,
387 _ => bug!("closure_sig_ty is not a fn-ptr: {:?}", ty),
392 /// Similar to `ClosureSubsts`; see the above documentation for more.
393 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug,
394 RustcEncodable, RustcDecodable, HashStable)]
395 pub struct GeneratorSubsts<'tcx> {
396 pub substs: SubstsRef<'tcx>,
399 struct SplitGeneratorSubsts<'tcx> {
403 upvar_kinds: &'tcx [Kind<'tcx>],
406 impl<'tcx> GeneratorSubsts<'tcx> {
407 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
408 let generics = tcx.generics_of(def_id);
409 let parent_len = generics.parent_count;
410 SplitGeneratorSubsts {
411 yield_ty: self.substs.type_at(parent_len),
412 return_ty: self.substs.type_at(parent_len + 1),
413 witness: self.substs.type_at(parent_len + 2),
414 upvar_kinds: &self.substs[parent_len + 3..],
418 /// This describes the types that can be contained in a generator.
419 /// It will be a type variable initially and unified in the last stages of typeck of a body.
420 /// It contains a tuple of all the types that could end up on a generator frame.
421 /// The state transformation MIR pass may only produce layouts which mention types
422 /// in this tuple. Upvars are not counted here.
423 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
424 self.split(def_id, tcx).witness
428 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
429 impl Iterator<Item=Ty<'tcx>> + 'tcx
431 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
432 upvar_kinds.iter().map(|t| {
433 if let UnpackedKind::Type(ty) = t.unpack() {
436 bug!("upvar should be type")
441 /// Returns the type representing the yield type of the generator.
442 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
443 self.split(def_id, tcx).yield_ty
446 /// Returns the type representing the return type of the generator.
447 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
448 self.split(def_id, tcx).return_ty
451 /// Returns the "generator signature", which consists of its yield
452 /// and return types.
454 /// N.B., some bits of the code prefers to see this wrapped in a
455 /// binder, but it never contains bound regions. Probably this
456 /// function should be removed.
457 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
458 ty::Binder::dummy(self.sig(def_id, tcx))
461 /// Returns the "generator signature", which consists of its yield
462 /// and return types.
463 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
465 yield_ty: self.yield_ty(def_id, tcx),
466 return_ty: self.return_ty(def_id, tcx),
471 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
472 /// Generator have not been resumed yet
473 pub const UNRESUMED: usize = 0;
474 /// Generator has returned / is completed
475 pub const RETURNED: usize = 1;
476 /// Generator has been poisoned
477 pub const POISONED: usize = 2;
479 const UNRESUMED_NAME: &'static str = "Unresumed";
480 const RETURNED_NAME: &'static str = "Returned";
481 const POISONED_NAME: &'static str = "Panicked";
483 /// The valid variant indices of this Generator.
485 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Range<VariantIdx> {
486 // FIXME requires optimized MIR
487 let num_variants = tcx.generator_layout(def_id).variant_fields.len();
488 (VariantIdx::new(0)..VariantIdx::new(num_variants))
491 /// The discriminant for the given variant. Panics if the variant_index is
494 pub fn discriminant_for_variant(
495 &self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>, variant_index: VariantIdx
497 // Generators don't support explicit discriminant values, so they are
498 // the same as the variant index.
499 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
500 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
503 /// The set of all discriminants for the Generator, enumerated with their
506 pub fn discriminants(
507 &'a self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>
508 ) -> impl Iterator<Item=(VariantIdx, Discr<'tcx>)> + Captures<'gcx> + 'a {
509 self.variant_range(def_id, tcx).map(move |index| {
510 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
514 /// Calls `f` with a reference to the name of the enumerator for the given
517 pub fn variant_name(&self, v: VariantIdx) -> Cow<'static, str> {
519 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
520 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
521 Self::POISONED => Cow::from(Self::POISONED_NAME),
522 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3))
526 /// The type of the state discriminant used in the generator type.
528 pub fn discr_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
532 /// This returns the types of the MIR locals which had to be stored across suspension points.
533 /// It is calculated in rustc_mir::transform::generator::StateTransform.
534 /// All the types here must be in the tuple in GeneratorInterior.
536 /// The locals are grouped by their variant number. Note that some locals may
537 /// be repeated in multiple variants.
539 pub fn state_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
540 impl Iterator<Item=impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a>
542 let layout = tcx.generator_layout(def_id);
543 layout.variant_fields.iter().map(move |variant| {
544 variant.iter().map(move |field| {
545 layout.field_tys[*field].subst(tcx, self.substs)
550 /// This is the types of the fields of a generator which are not stored in a
553 pub fn prefix_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
554 impl Iterator<Item=Ty<'tcx>> + 'a
556 self.upvar_tys(def_id, tcx)
560 #[derive(Debug, Copy, Clone)]
561 pub enum UpvarSubsts<'tcx> {
562 Closure(ClosureSubsts<'tcx>),
563 Generator(GeneratorSubsts<'tcx>),
566 impl<'tcx> UpvarSubsts<'tcx> {
568 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
569 impl Iterator<Item=Ty<'tcx>> + 'tcx
571 let upvar_kinds = match self {
572 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
573 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
575 upvar_kinds.iter().map(|t| {
576 if let UnpackedKind::Type(ty) = t.unpack() {
579 bug!("upvar should be type")
585 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash,
586 RustcEncodable, RustcDecodable, HashStable)]
587 pub enum ExistentialPredicate<'tcx> {
588 /// E.g., `Iterator`.
589 Trait(ExistentialTraitRef<'tcx>),
590 /// E.g., `Iterator::Item = T`.
591 Projection(ExistentialProjection<'tcx>),
596 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
597 /// Compares via an ordering that will not change if modules are reordered or other changes are
598 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
599 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
600 use self::ExistentialPredicate::*;
601 match (*self, *other) {
602 (Trait(_), Trait(_)) => Ordering::Equal,
603 (Projection(ref a), Projection(ref b)) =>
604 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
605 (AutoTrait(ref a), AutoTrait(ref b)) =>
606 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
607 (Trait(_), _) => Ordering::Less,
608 (Projection(_), Trait(_)) => Ordering::Greater,
609 (Projection(_), _) => Ordering::Less,
610 (AutoTrait(_), _) => Ordering::Greater,
616 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
617 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
618 -> ty::Predicate<'tcx> {
619 use crate::ty::ToPredicate;
620 match *self.skip_binder() {
621 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
622 ExistentialPredicate::Projection(p) =>
623 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
624 ExistentialPredicate::AutoTrait(did) => {
625 let trait_ref = Binder(ty::TraitRef {
627 substs: tcx.mk_substs_trait(self_ty, &[]),
629 trait_ref.to_predicate()
635 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
637 impl<'tcx> List<ExistentialPredicate<'tcx>> {
638 /// Returns the "principal def id" of this set of existential predicates.
640 /// A Rust trait object type consists (in addition to a lifetime bound)
641 /// of a set of trait bounds, which are separated into any number
642 /// of auto-trait bounds, and at most 1 non-auto-trait bound. The
643 /// non-auto-trait bound is called the "principal" of the trait
646 /// Only the principal can have methods or type parameters (because
647 /// auto traits can have neither of them). This is important, because
648 /// it means the auto traits can be treated as an unordered set (methods
649 /// would force an order for the vtable, while relating traits with
650 /// type parameters without knowing the order to relate them in is
651 /// a rather non-trivial task).
653 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
654 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
655 /// are the set `{Sync}`.
657 /// It is also possible to have a "trivial" trait object that
658 /// consists only of auto traits, with no principal - for example,
659 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
660 /// is `{Send, Sync}`, while there is no principal. These trait objects
661 /// have a "trivial" vtable consisting of just the size, alignment,
663 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
665 ExistentialPredicate::Trait(tr) => Some(tr),
670 pub fn principal_def_id(&self) -> Option<DefId> {
671 self.principal().map(|d| d.def_id)
675 pub fn projection_bounds<'a>(&'a self) ->
676 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
677 self.iter().filter_map(|predicate| {
679 ExistentialPredicate::Projection(p) => Some(p),
686 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
687 self.iter().filter_map(|predicate| {
689 ExistentialPredicate::AutoTrait(d) => Some(d),
696 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
697 pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> {
698 self.skip_binder().principal().map(Binder::bind)
701 pub fn principal_def_id(&self) -> Option<DefId> {
702 self.skip_binder().principal_def_id()
706 pub fn projection_bounds<'a>(&'a self) ->
707 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
708 self.skip_binder().projection_bounds().map(Binder::bind)
712 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
713 self.skip_binder().auto_traits()
716 pub fn iter<'a>(&'a self)
717 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
718 self.skip_binder().iter().cloned().map(Binder::bind)
722 /// A complete reference to a trait. These take numerous guises in syntax,
723 /// but perhaps the most recognizable form is in a where-clause:
727 /// This would be represented by a trait-reference where the `DefId` is the
728 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
729 /// and `U` as parameter 1.
731 /// Trait references also appear in object types like `Foo<U>`, but in
732 /// that case the `Self` parameter is absent from the substitutions.
734 /// Note that a `TraitRef` introduces a level of region binding, to
735 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
736 /// or higher-ranked object types.
737 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
738 pub struct TraitRef<'tcx> {
740 pub substs: SubstsRef<'tcx>,
743 impl<'tcx> TraitRef<'tcx> {
744 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
745 TraitRef { def_id: def_id, substs: substs }
748 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
749 /// are the parameters defined on trait.
750 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
753 substs: InternalSubsts::identity_for_item(tcx, def_id),
758 pub fn self_ty(&self) -> Ty<'tcx> {
759 self.substs.type_at(0)
762 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
763 // Select only the "input types" from a trait-reference. For
764 // now this is all the types that appear in the
765 // trait-reference, but it should eventually exclude
770 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
772 substs: SubstsRef<'tcx>)
773 -> ty::TraitRef<'tcx> {
774 let defs = tcx.generics_of(trait_id);
778 substs: tcx.intern_substs(&substs[..defs.params.len()])
783 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
785 impl<'tcx> PolyTraitRef<'tcx> {
786 pub fn self_ty(&self) -> Ty<'tcx> {
787 self.skip_binder().self_ty()
790 pub fn def_id(&self) -> DefId {
791 self.skip_binder().def_id
794 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
795 // Note that we preserve binding levels
796 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
800 /// An existential reference to a trait, where `Self` is erased.
801 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
803 /// exists T. T: Trait<'a, 'b, X, Y>
805 /// The substitutions don't include the erased `Self`, only trait
806 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
807 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
808 RustcEncodable, RustcDecodable, HashStable)]
809 pub struct ExistentialTraitRef<'tcx> {
811 pub substs: SubstsRef<'tcx>,
814 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
815 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
816 // Select only the "input types" from a trait-reference. For
817 // now this is all the types that appear in the
818 // trait-reference, but it should eventually exclude
823 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
824 trait_ref: ty::TraitRef<'tcx>)
825 -> ty::ExistentialTraitRef<'tcx> {
826 // Assert there is a Self.
827 trait_ref.substs.type_at(0);
829 ty::ExistentialTraitRef {
830 def_id: trait_ref.def_id,
831 substs: tcx.intern_substs(&trait_ref.substs[1..])
835 /// Object types don't have a self type specified. Therefore, when
836 /// we convert the principal trait-ref into a normal trait-ref,
837 /// you must give *some* self type. A common choice is `mk_err()`
838 /// or some placeholder type.
839 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
840 -> ty::TraitRef<'tcx> {
841 // otherwise the escaping vars would be captured by the binder
842 // debug_assert!(!self_ty.has_escaping_bound_vars());
846 substs: tcx.mk_substs_trait(self_ty, self.substs)
851 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
853 impl<'tcx> PolyExistentialTraitRef<'tcx> {
854 pub fn def_id(&self) -> DefId {
855 self.skip_binder().def_id
858 /// Object types don't have a self type specified. Therefore, when
859 /// we convert the principal trait-ref into a normal trait-ref,
860 /// you must give *some* self type. A common choice is `mk_err()`
861 /// or some placeholder type.
862 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
864 -> ty::PolyTraitRef<'tcx> {
865 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
869 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
870 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
871 /// (which would be represented by the type `PolyTraitRef ==
872 /// Binder<TraitRef>`). Note that when we instantiate,
873 /// erase, or otherwise "discharge" these bound vars, we change the
874 /// type from `Binder<T>` to just `T` (see
875 /// e.g., `liberate_late_bound_regions`).
876 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
877 pub struct Binder<T>(T);
880 /// Wraps `value` in a binder, asserting that `value` does not
881 /// contain any bound vars that would be bound by the
882 /// binder. This is commonly used to 'inject' a value T into a
883 /// different binding level.
884 pub fn dummy<'tcx>(value: T) -> Binder<T>
885 where T: TypeFoldable<'tcx>
887 debug_assert!(!value.has_escaping_bound_vars());
891 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
892 pub fn bind<'tcx>(value: T) -> Binder<T> {
896 /// Skips the binder and returns the "bound" value. This is a
897 /// risky thing to do because it's easy to get confused about
898 /// De Bruijn indices and the like. It is usually better to
899 /// discharge the binder using `no_bound_vars` or
900 /// `replace_late_bound_regions` or something like
901 /// that. `skip_binder` is only valid when you are either
902 /// extracting data that has nothing to do with bound vars, you
903 /// are doing some sort of test that does not involve bound
904 /// regions, or you are being very careful about your depth
907 /// Some examples where `skip_binder` is reasonable:
909 /// - extracting the `DefId` from a PolyTraitRef;
910 /// - comparing the self type of a PolyTraitRef to see if it is equal to
911 /// a type parameter `X`, since the type `X` does not reference any regions
912 pub fn skip_binder(&self) -> &T {
916 pub fn as_ref(&self) -> Binder<&T> {
920 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
921 where F: FnOnce(&T) -> U
923 self.as_ref().map_bound(f)
926 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
927 where F: FnOnce(T) -> U
932 /// Unwraps and returns the value within, but only if it contains
933 /// no bound vars at all. (In other words, if this binder --
934 /// and indeed any enclosing binder -- doesn't bind anything at
935 /// all.) Otherwise, returns `None`.
937 /// (One could imagine having a method that just unwraps a single
938 /// binder, but permits late-bound vars bound by enclosing
939 /// binders, but that would require adjusting the debruijn
940 /// indices, and given the shallow binding structure we often use,
941 /// would not be that useful.)
942 pub fn no_bound_vars<'tcx>(self) -> Option<T>
943 where T: TypeFoldable<'tcx>
945 if self.skip_binder().has_escaping_bound_vars() {
948 Some(self.skip_binder().clone())
952 /// Given two things that have the same binder level,
953 /// and an operation that wraps on their contents, executes the operation
954 /// and then wraps its result.
956 /// `f` should consider bound regions at depth 1 to be free, and
957 /// anything it produces with bound regions at depth 1 will be
958 /// bound in the resulting return value.
959 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
960 where F: FnOnce(T, U) -> R
962 Binder(f(self.0, u.0))
965 /// Splits the contents into two things that share the same binder
966 /// level as the original, returning two distinct binders.
968 /// `f` should consider bound regions at depth 1 to be free, and
969 /// anything it produces with bound regions at depth 1 will be
970 /// bound in the resulting return values.
971 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
972 where F: FnOnce(T) -> (U, V)
974 let (u, v) = f(self.0);
975 (Binder(u), Binder(v))
979 /// Represents the projection of an associated type. In explicit UFCS
980 /// form this would be written `<T as Trait<..>>::N`.
981 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
982 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
983 pub struct ProjectionTy<'tcx> {
984 /// The parameters of the associated item.
985 pub substs: SubstsRef<'tcx>,
987 /// The `DefId` of the `TraitItem` for the associated type `N`.
989 /// Note that this is not the `DefId` of the `TraitRef` containing this
990 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
991 pub item_def_id: DefId,
994 impl<'a, 'tcx> ProjectionTy<'tcx> {
995 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
996 /// associated item named `item_name`.
997 pub fn from_ref_and_name(
998 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
999 ) -> ProjectionTy<'tcx> {
1000 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
1001 item.kind == ty::AssociatedKind::Type &&
1002 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
1006 substs: trait_ref.substs,
1011 /// Extracts the underlying trait reference from this projection.
1012 /// For example, if this is a projection of `<T as Iterator>::Item`,
1013 /// then this function would return a `T: Iterator` trait reference.
1014 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
1015 let def_id = tcx.associated_item(self.item_def_id).container.id();
1018 substs: self.substs,
1022 pub fn self_ty(&self) -> Ty<'tcx> {
1023 self.substs.type_at(0)
1027 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1028 pub struct GenSig<'tcx> {
1029 pub yield_ty: Ty<'tcx>,
1030 pub return_ty: Ty<'tcx>,
1033 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
1035 impl<'tcx> PolyGenSig<'tcx> {
1036 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
1037 self.map_bound_ref(|sig| sig.yield_ty)
1039 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
1040 self.map_bound_ref(|sig| sig.return_ty)
1044 /// Signature of a function type, which I have arbitrarily
1045 /// decided to use to refer to the input/output types.
1047 /// - `inputs`: is the list of arguments and their modes.
1048 /// - `output`: is the return type.
1049 /// - `c_variadic`: indicates whether this is a C-variadic function.
1050 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
1051 Hash, RustcEncodable, RustcDecodable, HashStable)]
1052 pub struct FnSig<'tcx> {
1053 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1054 pub c_variadic: bool,
1055 pub unsafety: hir::Unsafety,
1059 impl<'tcx> FnSig<'tcx> {
1060 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1061 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1064 pub fn output(&self) -> Ty<'tcx> {
1065 self.inputs_and_output[self.inputs_and_output.len() - 1]
1068 // Create a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible method
1069 fn fake() -> FnSig<'tcx> {
1071 inputs_and_output: List::empty(),
1073 unsafety: hir::Unsafety::Normal,
1074 abi: abi::Abi::Rust,
1079 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
1081 impl<'tcx> PolyFnSig<'tcx> {
1083 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
1084 self.map_bound_ref(|fn_sig| fn_sig.inputs())
1087 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
1088 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1090 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
1091 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1094 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
1095 self.map_bound_ref(|fn_sig| fn_sig.output())
1097 pub fn c_variadic(&self) -> bool {
1098 self.skip_binder().c_variadic
1100 pub fn unsafety(&self) -> hir::Unsafety {
1101 self.skip_binder().unsafety
1103 pub fn abi(&self) -> abi::Abi {
1104 self.skip_binder().abi
1108 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1111 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1112 Hash, RustcEncodable, RustcDecodable, HashStable)]
1113 pub struct ParamTy {
1115 pub name: InternedString,
1118 impl<'a, 'gcx, 'tcx> ParamTy {
1119 pub fn new(index: u32, name: InternedString) -> ParamTy {
1120 ParamTy { index, name: name }
1123 pub fn for_self() -> ParamTy {
1124 ParamTy::new(0, kw::SelfUpper.as_interned_str())
1127 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1128 ParamTy::new(def.index, def.name)
1131 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1132 tcx.mk_ty_param(self.index, self.name)
1135 pub fn is_self(&self) -> bool {
1136 // FIXME(#50125): Ignoring `Self` with `index != 0` might lead to weird behavior elsewhere,
1137 // but this should only be possible when using `-Z continue-parse-after-error` like
1138 // `compile-fail/issue-36638.rs`.
1139 self.name.as_symbol() == kw::SelfUpper && self.index == 0
1143 #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable,
1144 Eq, PartialEq, Ord, PartialOrd, HashStable)]
1145 pub struct ParamConst {
1147 pub name: InternedString,
1150 impl<'a, 'gcx, 'tcx> ParamConst {
1151 pub fn new(index: u32, name: InternedString) -> ParamConst {
1152 ParamConst { index, name }
1155 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1156 ParamConst::new(def.index, def.name)
1159 pub fn to_const(self, tcx: TyCtxt<'a, 'gcx, 'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
1160 tcx.mk_const_param(self.index, self.name, ty)
1165 /// A [De Bruijn index][dbi] is a standard means of representing
1166 /// regions (and perhaps later types) in a higher-ranked setting. In
1167 /// particular, imagine a type like this:
1169 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1172 /// | +------------+ 0 | |
1174 /// +--------------------------------+ 1 |
1176 /// +------------------------------------------+ 0
1178 /// In this type, there are two binders (the outer fn and the inner
1179 /// fn). We need to be able to determine, for any given region, which
1180 /// fn type it is bound by, the inner or the outer one. There are
1181 /// various ways you can do this, but a De Bruijn index is one of the
1182 /// more convenient and has some nice properties. The basic idea is to
1183 /// count the number of binders, inside out. Some examples should help
1184 /// clarify what I mean.
1186 /// Let's start with the reference type `&'b isize` that is the first
1187 /// argument to the inner function. This region `'b` is assigned a De
1188 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1189 /// fn). The region `'a` that appears in the second argument type (`&'a
1190 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1191 /// second-innermost binder". (These indices are written on the arrays
1192 /// in the diagram).
1194 /// What is interesting is that De Bruijn index attached to a particular
1195 /// variable will vary depending on where it appears. For example,
1196 /// the final type `&'a char` also refers to the region `'a` declared on
1197 /// the outermost fn. But this time, this reference is not nested within
1198 /// any other binders (i.e., it is not an argument to the inner fn, but
1199 /// rather the outer one). Therefore, in this case, it is assigned a
1200 /// De Bruijn index of 0, because the innermost binder in that location
1201 /// is the outer fn.
1203 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1204 pub struct DebruijnIndex {
1205 DEBUG_FORMAT = "DebruijnIndex({})",
1206 const INNERMOST = 0,
1210 pub type Region<'tcx> = &'tcx RegionKind;
1212 /// Representation of regions.
1214 /// Unlike types, most region variants are "fictitious", not concrete,
1215 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1216 /// ones representing concrete regions.
1218 /// ## Bound Regions
1220 /// These are regions that are stored behind a binder and must be substituted
1221 /// with some concrete region before being used. There are two kind of
1222 /// bound regions: early-bound, which are bound in an item's `Generics`,
1223 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1224 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1225 /// the likes of `liberate_late_bound_regions`. The distinction exists
1226 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1228 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1229 /// outside their binder, e.g., in types passed to type inference, and
1230 /// should first be substituted (by placeholder regions, free regions,
1231 /// or region variables).
1233 /// ## Placeholder and Free Regions
1235 /// One often wants to work with bound regions without knowing their precise
1236 /// identity. For example, when checking a function, the lifetime of a borrow
1237 /// can end up being assigned to some region parameter. In these cases,
1238 /// it must be ensured that bounds on the region can't be accidentally
1239 /// assumed without being checked.
1241 /// To do this, we replace the bound regions with placeholder markers,
1242 /// which don't satisfy any relation not explicitly provided.
1244 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1245 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1246 /// to be used. These also support explicit bounds: both the internally-stored
1247 /// *scope*, which the region is assumed to outlive, as well as other
1248 /// relations stored in the `FreeRegionMap`. Note that these relations
1249 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1250 /// `resolve_regions_and_report_errors`.
1252 /// When working with higher-ranked types, some region relations aren't
1253 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1254 /// `RePlaceholder` is designed for this purpose. In these contexts,
1255 /// there's also the risk that some inference variable laying around will
1256 /// get unified with your placeholder region: if you want to check whether
1257 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1258 /// with a placeholder region `'%a`, the variable `'_` would just be
1259 /// instantiated to the placeholder region `'%a`, which is wrong because
1260 /// the inference variable is supposed to satisfy the relation
1261 /// *for every value of the placeholder region*. To ensure that doesn't
1262 /// happen, you can use `leak_check`. This is more clearly explained
1263 /// by the [rustc guide].
1265 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1266 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1267 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1268 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1269 pub enum RegionKind {
1270 /// Region bound in a type or fn declaration which will be
1271 /// substituted 'early' -- that is, at the same time when type
1272 /// parameters are substituted.
1273 ReEarlyBound(EarlyBoundRegion),
1275 /// Region bound in a function scope, which will be substituted when the
1276 /// function is called.
1277 ReLateBound(DebruijnIndex, BoundRegion),
1279 /// When checking a function body, the types of all arguments and so forth
1280 /// that refer to bound region parameters are modified to refer to free
1281 /// region parameters.
1284 /// A concrete region naming some statically determined scope
1285 /// (e.g., an expression or sequence of statements) within the
1286 /// current function.
1287 ReScope(region::Scope),
1289 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1292 /// A region variable. Should not exist after typeck.
1295 /// A placeholder region - basically the higher-ranked version of ReFree.
1296 /// Should not exist after typeck.
1297 RePlaceholder(ty::PlaceholderRegion),
1299 /// Empty lifetime is for data that is never accessed.
1300 /// Bottom in the region lattice. We treat ReEmpty somewhat
1301 /// specially; at least right now, we do not generate instances of
1302 /// it during the GLB computations, but rather
1303 /// generate an error instead. This is to improve error messages.
1304 /// The only way to get an instance of ReEmpty is to have a region
1305 /// variable with no constraints.
1308 /// Erased region, used by trait selection, in MIR and during codegen.
1311 /// These are regions bound in the "defining type" for a
1312 /// closure. They are used ONLY as part of the
1313 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1314 /// See `ClosureRegionRequirements` for more details.
1315 ReClosureBound(RegionVid),
1318 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1320 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1321 pub struct EarlyBoundRegion {
1324 pub name: InternedString,
1327 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1332 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1333 pub struct ConstVid<'tcx> {
1335 pub phantom: PhantomData<&'tcx ()>,
1338 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1343 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1344 pub struct FloatVid {
1349 pub struct RegionVid {
1350 DEBUG_FORMAT = custom,
1354 impl Atom for RegionVid {
1355 fn index(self) -> usize {
1360 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1361 Hash, RustcEncodable, RustcDecodable, HashStable)]
1367 /// A `FreshTy` is one that is generated as a replacement for an
1368 /// unbound type variable. This is convenient for caching etc. See
1369 /// `infer::freshen` for more details.
1376 pub struct BoundVar { .. }
1379 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1380 pub struct BoundTy {
1382 pub kind: BoundTyKind,
1385 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1386 pub enum BoundTyKind {
1388 Param(InternedString),
1391 impl_stable_hash_for!(struct BoundTy { var, kind });
1392 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1394 impl From<BoundVar> for BoundTy {
1395 fn from(var: BoundVar) -> Self {
1398 kind: BoundTyKind::Anon,
1403 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1404 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash,
1405 Debug, RustcEncodable, RustcDecodable, HashStable)]
1406 pub struct ExistentialProjection<'tcx> {
1407 pub item_def_id: DefId,
1408 pub substs: SubstsRef<'tcx>,
1412 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1414 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1415 /// Extracts the underlying existential trait reference from this projection.
1416 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1417 /// then this function would return a `exists T. T: Iterator` existential trait
1419 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1420 let def_id = tcx.associated_item(self.item_def_id).container.id();
1421 ty::ExistentialTraitRef{
1423 substs: self.substs,
1427 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1429 -> ty::ProjectionPredicate<'tcx>
1431 // otherwise the escaping regions would be captured by the binders
1432 debug_assert!(!self_ty.has_escaping_bound_vars());
1434 ty::ProjectionPredicate {
1435 projection_ty: ty::ProjectionTy {
1436 item_def_id: self.item_def_id,
1437 substs: tcx.mk_substs_trait(self_ty, self.substs),
1444 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1445 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1446 -> ty::PolyProjectionPredicate<'tcx> {
1447 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1450 pub fn item_def_id(&self) -> DefId {
1451 return self.skip_binder().item_def_id;
1455 impl DebruijnIndex {
1456 /// Returns the resulting index when this value is moved into
1457 /// `amount` number of new binders. So, e.g., if you had
1459 /// for<'a> fn(&'a x)
1461 /// and you wanted to change it to
1463 /// for<'a> fn(for<'b> fn(&'a x))
1465 /// you would need to shift the index for `'a` into a new binder.
1467 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1468 DebruijnIndex::from_u32(self.as_u32() + amount)
1471 /// Update this index in place by shifting it "in" through
1472 /// `amount` number of binders.
1473 pub fn shift_in(&mut self, amount: u32) {
1474 *self = self.shifted_in(amount);
1477 /// Returns the resulting index when this value is moved out from
1478 /// `amount` number of new binders.
1480 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1481 DebruijnIndex::from_u32(self.as_u32() - amount)
1484 /// Update in place by shifting out from `amount` binders.
1485 pub fn shift_out(&mut self, amount: u32) {
1486 *self = self.shifted_out(amount);
1489 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1490 /// innermost binder. That is, if we have something bound at `to_binder`,
1491 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1492 /// when moving a region out from inside binders:
1495 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1496 /// // Binder: D3 D2 D1 ^^
1499 /// Here, the region `'a` would have the De Bruijn index D3,
1500 /// because it is the bound 3 binders out. However, if we wanted
1501 /// to refer to that region `'a` in the second argument (the `_`),
1502 /// those two binders would not be in scope. In that case, we
1503 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1504 /// De Bruijn index of `'a` to D1 (the innermost binder).
1506 /// If we invoke `shift_out_to_binder` and the region is in fact
1507 /// bound by one of the binders we are shifting out of, that is an
1508 /// error (and should fail an assertion failure).
1509 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1510 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1514 impl_stable_hash_for!(struct DebruijnIndex { private });
1516 /// Region utilities
1518 /// Is this region named by the user?
1519 pub fn has_name(&self) -> bool {
1521 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1522 RegionKind::ReLateBound(_, br) => br.is_named(),
1523 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1524 RegionKind::ReScope(..) => false,
1525 RegionKind::ReStatic => true,
1526 RegionKind::ReVar(..) => false,
1527 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1528 RegionKind::ReEmpty => false,
1529 RegionKind::ReErased => false,
1530 RegionKind::ReClosureBound(..) => false,
1534 pub fn is_late_bound(&self) -> bool {
1536 ty::ReLateBound(..) => true,
1541 pub fn is_placeholder(&self) -> bool {
1543 ty::RePlaceholder(..) => true,
1548 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1550 ty::ReLateBound(debruijn, _) => debruijn >= index,
1555 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1556 /// innermost binder. That is, if we have something bound at `to_binder`,
1557 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1558 /// when moving a region out from inside binders:
1561 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1562 /// // Binder: D3 D2 D1 ^^
1565 /// Here, the region `'a` would have the De Bruijn index D3,
1566 /// because it is the bound 3 binders out. However, if we wanted
1567 /// to refer to that region `'a` in the second argument (the `_`),
1568 /// those two binders would not be in scope. In that case, we
1569 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1570 /// De Bruijn index of `'a` to D1 (the innermost binder).
1572 /// If we invoke `shift_out_to_binder` and the region is in fact
1573 /// bound by one of the binders we are shifting out of, that is an
1574 /// error (and should fail an assertion failure).
1575 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1577 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1578 debruijn.shifted_out_to_binder(to_binder),
1585 pub fn keep_in_local_tcx(&self) -> bool {
1586 if let ty::ReVar(..) = self {
1593 pub fn type_flags(&self) -> TypeFlags {
1594 let mut flags = TypeFlags::empty();
1596 if self.keep_in_local_tcx() {
1597 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1602 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1603 flags = flags | TypeFlags::HAS_RE_INFER;
1605 ty::RePlaceholder(..) => {
1606 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1607 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1609 ty::ReLateBound(..) => {
1610 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1612 ty::ReEarlyBound(..) => {
1613 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1614 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1619 ty::ReScope { .. } => {
1620 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1624 ty::ReClosureBound(..) => {
1625 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1630 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1631 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1634 debug!("type_flags({:?}) = {:?}", self, flags);
1639 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1640 /// For example, consider the regions in this snippet of code:
1644 /// ^^ -- early bound, declared on an impl
1646 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1647 /// ^^ ^^ ^ anonymous, late-bound
1648 /// | early-bound, appears in where-clauses
1649 /// late-bound, appears only in fn args
1654 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1655 /// of the impl, and for all the other highlighted regions, it
1656 /// would return the `DefId` of the function. In other cases (not shown), this
1657 /// function might return the `DefId` of a closure.
1658 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1660 ty::ReEarlyBound(br) => {
1661 tcx.parent(br.def_id).unwrap()
1663 ty::ReFree(fr) => fr.scope,
1664 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1670 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1671 pub fn is_unit(&self) -> bool {
1673 Tuple(ref tys) => tys.is_empty(),
1678 pub fn is_never(&self) -> bool {
1685 /// Checks whether a type is definitely uninhabited. This is
1686 /// conservative: for some types that are uninhabited we return `false`,
1687 /// but we only return `true` for types that are definitely uninhabited.
1688 /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
1689 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1690 /// size, to account for partial initialisation. See #49298 for details.)
1691 pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool {
1692 // FIXME(varkor): we can make this less conversative by substituting concrete
1696 ty::Adt(def, _) if def.is_union() => {
1697 // For now, `union`s are never considered uninhabited.
1700 ty::Adt(def, _) => {
1701 // Any ADT is uninhabited if either:
1702 // (a) It has no variants (i.e. an empty `enum`);
1703 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1704 // one uninhabited field.
1705 def.variants.iter().all(|var| {
1706 var.fields.iter().any(|field| {
1707 tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
1711 ty::Tuple(tys) => tys.iter().any(|ty| {
1712 ty.expect_ty().conservative_is_privately_uninhabited(tcx)
1714 ty::Array(ty, len) => {
1715 match len.assert_usize(tcx) {
1716 // If the array is definitely non-empty, it's uninhabited if
1717 // the type of its elements is uninhabited.
1718 Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
1723 // References to uninitialised memory is valid for any type, including
1724 // 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,
1747 pub fn is_ty_infer(&self) -> bool {
1754 pub fn is_phantom_data(&self) -> bool {
1755 if let Adt(def, _) = self.sty {
1756 def.is_phantom_data()
1762 pub fn is_bool(&self) -> bool { self.sty == Bool }
1764 pub fn is_param(&self, index: u32) -> bool {
1766 ty::Param(ref data) => data.index == index,
1771 pub fn is_self(&self) -> bool {
1773 Param(ref p) => p.is_self(),
1778 pub fn is_slice(&self) -> bool {
1780 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1781 Slice(_) | Str => true,
1789 pub fn is_simd(&self) -> bool {
1791 Adt(def, _) => def.repr.simd(),
1796 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1798 Array(ty, _) | Slice(ty) => ty,
1799 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1800 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1804 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1806 Adt(def, substs) => {
1807 def.non_enum_variant().fields[0].ty(tcx, substs)
1809 _ => bug!("simd_type called on invalid type")
1813 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1815 Adt(def, _) => def.non_enum_variant().fields.len(),
1816 _ => bug!("simd_size called on invalid type")
1820 pub fn is_region_ptr(&self) -> bool {
1827 pub fn is_mutable_pointer(&self) -> bool {
1829 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1830 Ref(_, _, hir::Mutability::MutMutable) => true,
1835 pub fn is_unsafe_ptr(&self) -> bool {
1837 RawPtr(_) => return true,
1842 /// Returns `true` if this type is an `Arc<T>`.
1843 pub fn is_arc(&self) -> bool {
1845 Adt(def, _) => def.is_arc(),
1850 /// Returns `true` if this type is an `Rc<T>`.
1851 pub fn is_rc(&self) -> bool {
1853 Adt(def, _) => def.is_rc(),
1858 pub fn is_box(&self) -> bool {
1860 Adt(def, _) => def.is_box(),
1865 /// panics if called on any type other than `Box<T>`
1866 pub fn boxed_ty(&self) -> Ty<'tcx> {
1868 Adt(def, substs) if def.is_box() => substs.type_at(0),
1869 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1873 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1874 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1875 /// contents are abstract to rustc.)
1876 pub fn is_scalar(&self) -> bool {
1878 Bool | Char | Int(_) | Float(_) | Uint(_) |
1879 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1880 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1885 /// Returns `true` if this type is a floating point type.
1886 pub fn is_floating_point(&self) -> bool {
1889 Infer(FloatVar(_)) => true,
1894 pub fn is_trait(&self) -> bool {
1896 Dynamic(..) => true,
1901 pub fn is_enum(&self) -> bool {
1903 Adt(adt_def, _) => {
1910 pub fn is_closure(&self) -> bool {
1912 Closure(..) => true,
1917 pub fn is_generator(&self) -> bool {
1919 Generator(..) => true,
1925 pub fn is_integral(&self) -> bool {
1927 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1932 pub fn is_fresh_ty(&self) -> bool {
1934 Infer(FreshTy(_)) => true,
1939 pub fn is_fresh(&self) -> bool {
1941 Infer(FreshTy(_)) => true,
1942 Infer(FreshIntTy(_)) => true,
1943 Infer(FreshFloatTy(_)) => true,
1948 pub fn is_char(&self) -> bool {
1956 pub fn is_fp(&self) -> bool {
1958 Infer(FloatVar(_)) | Float(_) => true,
1963 pub fn is_numeric(&self) -> bool {
1964 self.is_integral() || self.is_fp()
1967 pub fn is_signed(&self) -> bool {
1974 pub fn is_pointer_sized(&self) -> bool {
1976 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
1981 pub fn is_machine(&self) -> bool {
1983 Int(..) | Uint(..) | Float(..) => true,
1988 pub fn has_concrete_skeleton(&self) -> bool {
1990 Param(_) | Infer(_) | Error => false,
1995 /// Returns the type and mutability of `*ty`.
1997 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1998 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
1999 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2001 Adt(def, _) if def.is_box() => {
2003 ty: self.boxed_ty(),
2004 mutbl: hir::MutImmutable,
2007 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
2008 RawPtr(mt) if explicit => Some(mt),
2013 /// Returns the type of `ty[i]`.
2014 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2016 Array(ty, _) | Slice(ty) => Some(ty),
2021 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
2023 FnDef(def_id, substs) => {
2024 tcx.fn_sig(def_id).subst(tcx, substs)
2027 Error => { // ignore errors (#54954)
2028 ty::Binder::dummy(FnSig::fake())
2030 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
2034 pub fn is_fn(&self) -> bool {
2036 FnDef(..) | FnPtr(_) => true,
2041 pub fn is_impl_trait(&self) -> bool {
2049 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2051 Adt(adt, _) => Some(adt),
2056 /// If the type contains variants, returns the valid range of variant indices.
2057 /// FIXME This requires the optimized MIR in the case of generators.
2059 pub fn variant_range(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option<Range<VariantIdx>> {
2061 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2062 TyKind::Generator(def_id, substs, _) => Some(substs.variant_range(def_id, tcx)),
2067 /// If the type contains variants, returns the variant for `variant_index`.
2068 /// Panics if `variant_index` is out of range.
2069 /// FIXME This requires the optimized MIR in the case of generators.
2071 pub fn discriminant_for_variant(
2073 tcx: TyCtxt<'a, 'gcx, 'tcx>,
2074 variant_index: VariantIdx
2075 ) -> Option<Discr<'tcx>> {
2077 TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)),
2078 TyKind::Generator(def_id, substs, _) =>
2079 Some(substs.discriminant_for_variant(def_id, tcx, variant_index)),
2084 /// Push onto `out` the regions directly referenced from this type (but not
2085 /// types reachable from this type via `walk_tys`). This ignores late-bound
2086 /// regions binders.
2087 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
2089 Ref(region, _, _) => {
2092 Dynamic(ref obj, region) => {
2094 if let Some(principal) = obj.principal() {
2095 out.extend(principal.skip_binder().substs.regions());
2098 Adt(_, substs) | Opaque(_, substs) => {
2099 out.extend(substs.regions())
2101 Closure(_, ClosureSubsts { ref substs }) |
2102 Generator(_, GeneratorSubsts { ref substs }, _) => {
2103 out.extend(substs.regions())
2105 Projection(ref data) | UnnormalizedProjection(ref data) => {
2106 out.extend(data.substs.regions())
2110 GeneratorWitness(..) |
2131 /// When we create a closure, we record its kind (i.e., what trait
2132 /// it implements) into its `ClosureSubsts` using a type
2133 /// parameter. This is kind of a phantom type, except that the
2134 /// most convenient thing for us to are the integral types. This
2135 /// function converts such a special type into the closure
2136 /// kind. To go the other way, use
2137 /// `tcx.closure_kind_ty(closure_kind)`.
2139 /// Note that during type checking, we use an inference variable
2140 /// to represent the closure kind, because it has not yet been
2141 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2142 /// is complete, that type variable will be unified.
2143 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2145 Int(int_ty) => match int_ty {
2146 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
2147 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2148 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2149 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2154 Error => Some(ty::ClosureKind::Fn),
2156 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2160 /// Fast path helper for testing if a type is `Sized`.
2162 /// Returning true means the type is known to be sized. Returning
2163 /// `false` means nothing -- could be sized, might not be.
2164 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
2166 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
2167 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
2168 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
2169 ty::Char | ty::Ref(..) | ty::Generator(..) |
2170 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
2171 ty::Never | ty::Error =>
2174 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2178 tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx))
2181 ty::Adt(def, _substs) =>
2182 def.sized_constraint(tcx).is_empty(),
2184 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2186 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2188 ty::Infer(ty::TyVar(_)) => false,
2191 ty::Placeholder(..) |
2192 ty::Infer(ty::FreshTy(_)) |
2193 ty::Infer(ty::FreshIntTy(_)) |
2194 ty::Infer(ty::FreshFloatTy(_)) =>
2195 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2200 /// Typed constant value.
2201 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable,
2202 Eq, PartialEq, Ord, PartialOrd, HashStable)]
2203 pub struct Const<'tcx> {
2206 pub val: ConstValue<'tcx>,
2209 #[cfg(target_arch = "x86_64")]
2210 static_assert_size!(Const<'_>, 48);
2212 impl<'tcx> Const<'tcx> {
2219 val: ConstValue::Scalar(val),
2226 tcx: TyCtxt<'_, '_, 'tcx>,
2228 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2230 let ty = tcx.lift_to_global(&ty).unwrap();
2231 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2232 panic!("could not compute layout for {:?}: {:?}", ty, e)
2234 let truncated = truncate(bits, size);
2235 assert_eq!(truncated, bits, "from_bits called with untruncated value");
2236 Self::from_scalar(Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
2240 pub fn zero_sized(ty: Ty<'tcx>) -> Self {
2241 Self::from_scalar(Scalar::Bits { bits: 0, size: 0 }, ty)
2245 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> Self {
2246 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2250 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> Self {
2251 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2257 tcx: TyCtxt<'_, '_, 'tcx>,
2258 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2260 if self.ty != ty.value {
2263 let ty = tcx.lift_to_global(&ty).unwrap();
2264 let size = tcx.layout_of(ty).ok()?.size;
2265 self.val.try_to_bits(size)
2269 pub fn to_ptr(&self) -> Option<Pointer> {
2270 self.val.try_to_ptr()
2276 tcx: TyCtxt<'_, '_, '_>,
2277 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2279 assert_eq!(self.ty, ty.value);
2280 let ty = tcx.lift_to_global(&ty).unwrap();
2281 let size = tcx.layout_of(ty).ok()?.size;
2282 self.val.try_to_bits(size)
2286 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2287 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2295 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2296 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2302 tcx: TyCtxt<'_, '_, '_>,
2303 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2305 self.assert_bits(tcx, ty).unwrap_or_else(||
2306 bug!("expected bits of {}, got {:#?}", ty.value, self))
2310 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2311 self.assert_usize(tcx).unwrap_or_else(||
2312 bug!("expected constant usize, got {:#?}", self))
2316 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
2318 /// An inference variable for a const, for use in const generics.
2319 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd,
2320 Ord, RustcEncodable, RustcDecodable, Hash, HashStable)]
2321 pub enum InferConst<'tcx> {
2322 /// Infer the value of the const.
2323 Var(ConstVid<'tcx>),
2324 /// A fresh const variable. See `infer::freshen` for more details.
2326 /// Canonicalized const variable, used only when preparing a trait query.
2327 Canonical(DebruijnIndex, BoundVar),