1 //! This module contains `TyKind` and its major components.
3 #![cfg_attr(not(bootstrap), allow(rustc::usage_of_ty_tykind))]
6 use crate::hir::def_id::DefId;
7 use crate::infer::canonical::Canonical;
8 use crate::mir::interpret::ConstValue;
9 use crate::middle::region;
10 use polonius_engine::Atom;
11 use rustc_data_structures::indexed_vec::Idx;
12 use rustc_macros::HashStable;
13 use crate::ty::subst::{InternalSubsts, Subst, SubstsRef, Kind, UnpackedKind};
14 use crate::ty::{self, AdtDef, Discr, DefIdTree, TypeFlags, Ty, TyCtxt, TypeFoldable};
15 use crate::ty::{List, TyS, ParamEnvAnd, ParamEnv};
16 use crate::ty::layout::VariantIdx;
17 use crate::util::captures::Captures;
18 use crate::mir::interpret::{Scalar, Pointer};
20 use smallvec::SmallVec;
22 use std::cmp::Ordering;
23 use std::marker::PhantomData;
25 use rustc_target::spec::abi;
26 use syntax::ast::{self, Ident};
27 use syntax::symbol::{kw, InternedString};
32 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
33 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
34 pub struct TypeAndMut<'tcx> {
36 pub mutbl: hir::Mutability,
39 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
40 RustcEncodable, RustcDecodable, Copy, HashStable)]
41 /// A "free" region `fr` can be interpreted as "some region
42 /// at least as big as the scope `fr.scope`".
43 pub struct FreeRegion {
45 pub bound_region: BoundRegion,
48 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
49 RustcEncodable, RustcDecodable, Copy, HashStable)]
50 pub enum BoundRegion {
51 /// An anonymous region parameter for a given fn (&T)
54 /// Named region parameters for functions (a in &'a T)
56 /// The `DefId` is needed to distinguish free regions in
57 /// the event of shadowing.
58 BrNamed(DefId, InternedString),
60 /// Anonymous region for the implicit env pointer parameter
66 pub fn is_named(&self) -> bool {
68 BoundRegion::BrNamed(..) => true,
73 /// When canonicalizing, we replace unbound inference variables and free
74 /// regions with anonymous late bound regions. This method asserts that
75 /// we have an anonymous late bound region, which hence may refer to
76 /// a canonical variable.
77 pub fn assert_bound_var(&self) -> BoundVar {
79 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
80 _ => bug!("bound region is not anonymous"),
85 /// N.B., if you change this, you'll probably want to change the corresponding
86 /// AST structure in `libsyntax/ast.rs` as well.
87 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
88 RustcEncodable, RustcDecodable, HashStable, Debug)]
89 pub enum TyKind<'tcx> {
90 /// The primitive boolean type. Written as `bool`.
93 /// The primitive character type; holds a Unicode scalar value
94 /// (a non-surrogate code point). Written as `char`.
97 /// A primitive signed integer type. For example, `i32`.
100 /// A primitive unsigned integer type. For example, `u32`.
103 /// A primitive floating-point type. For example, `f64`.
106 /// Structures, enumerations and unions.
108 /// InternalSubsts here, possibly against intuition, *may* contain `Param`s.
109 /// That is, even after substitution it is possible that there are type
110 /// variables. This happens when the `Adt` corresponds to an ADT
111 /// definition and not a concrete use of it.
112 Adt(&'tcx AdtDef, SubstsRef<'tcx>),
114 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
117 /// The pointee of a string slice. Written as `str`.
120 /// An array with the given length. Written as `[T; n]`.
121 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
123 /// The pointee of an array slice. Written as `[T]`.
126 /// A raw pointer. Written as `*mut T` or `*const T`
127 RawPtr(TypeAndMut<'tcx>),
129 /// A reference; a pointer with an associated lifetime. Written as
130 /// `&'a mut T` or `&'a T`.
131 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
133 /// The anonymous type of a function declaration/definition. Each
134 /// function has a unique type, which is output (for a function
135 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
137 /// For example the type of `bar` here:
140 /// fn foo() -> i32 { 1 }
141 /// let bar = foo; // bar: fn() -> i32 {foo}
143 FnDef(DefId, SubstsRef<'tcx>),
145 /// A pointer to a function. Written as `fn() -> i32`.
147 /// For example the type of `bar` here:
150 /// fn foo() -> i32 { 1 }
151 /// let bar: fn() -> i32 = foo;
153 FnPtr(PolyFnSig<'tcx>),
155 /// A trait, defined with `trait`.
156 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
158 /// The anonymous type of a closure. Used to represent the type of
160 Closure(DefId, ClosureSubsts<'tcx>),
162 /// The anonymous type of a generator. Used to represent the type of
164 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
166 /// A type representin the types stored inside a generator.
167 /// This should only appear in GeneratorInteriors.
168 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
170 /// The never type `!`
173 /// A tuple type. For example, `(i32, bool)`.
174 Tuple(SubstsRef<'tcx>),
176 /// The projection of an associated type. For example,
177 /// `<T as Trait<..>>::N`.
178 Projection(ProjectionTy<'tcx>),
180 /// A placeholder type used when we do not have enough information
181 /// to normalize the projection of an associated type to an
182 /// existing concrete type. Currently only used with chalk-engine.
183 UnnormalizedProjection(ProjectionTy<'tcx>),
185 /// Opaque (`impl Trait`) type found in a return type.
186 /// The `DefId` comes either from
187 /// * the `impl Trait` ast::Ty node,
188 /// * or the `existential type` declaration
189 /// The substitutions are for the generics of the function in question.
190 /// After typeck, the concrete type can be found in the `types` map.
191 Opaque(DefId, SubstsRef<'tcx>),
193 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
196 /// Bound type variable, used only when preparing a trait query.
197 Bound(ty::DebruijnIndex, BoundTy),
199 /// A placeholder type - universally quantified higher-ranked type.
200 Placeholder(ty::PlaceholderType),
202 /// A type variable used during type checking.
205 /// A placeholder for a type which could not be computed; this is
206 /// propagated to avoid useless error messages.
210 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
211 #[cfg(target_arch = "x86_64")]
212 static_assert_size!(TyKind<'_>, 24);
214 /// A closure can be modeled as a struct that looks like:
216 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
224 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
225 /// in scope on the function that defined the closure,
226 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
227 /// is rather hackily encoded via a scalar type. See
228 /// `TyS::to_opt_closure_kind` for details.
229 /// - CS represents the *closure signature*, representing as a `fn()`
230 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
231 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
233 /// - U0...Uk are type parameters representing the types of its upvars
234 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
235 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
237 /// So, for example, given this function:
239 /// fn foo<'a, T>(data: &'a mut T) {
240 /// do(|| data.count += 1)
243 /// the type of the closure would be something like:
245 /// struct Closure<'a, T, U0> {
249 /// Note that the type of the upvar is not specified in the struct.
250 /// You may wonder how the impl would then be able to use the upvar,
251 /// if it doesn't know it's type? The answer is that the impl is
252 /// (conceptually) not fully generic over Closure but rather tied to
253 /// instances with the expected upvar types:
255 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
259 /// You can see that the *impl* fully specified the type of the upvar
260 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
261 /// (Here, I am assuming that `data` is mut-borrowed.)
263 /// Now, the last question you may ask is: Why include the upvar types
264 /// as extra type parameters? The reason for this design is that the
265 /// upvar types can reference lifetimes that are internal to the
266 /// creating function. In my example above, for example, the lifetime
267 /// `'b` represents the scope of the closure itself; this is some
268 /// subset of `foo`, probably just the scope of the call to the to
269 /// `do()`. If we just had the lifetime/type parameters from the
270 /// enclosing function, we couldn't name this lifetime `'b`. Note that
271 /// there can also be lifetimes in the types of the upvars themselves,
272 /// if one of them happens to be a reference to something that the
273 /// creating fn owns.
275 /// OK, you say, so why not create a more minimal set of parameters
276 /// that just includes the extra lifetime parameters? The answer is
277 /// primarily that it would be hard --- we don't know at the time when
278 /// we create the closure type what the full types of the upvars are,
279 /// nor do we know which are borrowed and which are not. In this
280 /// design, we can just supply a fresh type parameter and figure that
283 /// All right, you say, but why include the type parameters from the
284 /// original function then? The answer is that codegen may need them
285 /// when monomorphizing, and they may not appear in the upvars. A
286 /// closure could capture no variables but still make use of some
287 /// in-scope type parameter with a bound (e.g., if our example above
288 /// had an extra `U: Default`, and the closure called `U::default()`).
290 /// There is another reason. This design (implicitly) prohibits
291 /// closures from capturing themselves (except via a trait
292 /// object). This simplifies closure inference considerably, since it
293 /// means that when we infer the kind of a closure or its upvars, we
294 /// don't have to handle cycles where the decisions we make for
295 /// closure C wind up influencing the decisions we ought to make for
296 /// closure C (which would then require fixed point iteration to
297 /// handle). Plus it fixes an ICE. :P
301 /// Generators are handled similarly in `GeneratorSubsts`. The set of
302 /// type parameters is similar, but the role of CK and CS are
303 /// different. CK represents the "yield type" and CS represents the
304 /// "return type" of the generator.
305 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
306 Debug, RustcEncodable, RustcDecodable, HashStable)]
307 pub struct ClosureSubsts<'tcx> {
308 /// Lifetime and type parameters from the enclosing function,
309 /// concatenated with the types of the upvars.
311 /// These are separated out because codegen wants to pass them around
312 /// when monomorphizing.
313 pub substs: SubstsRef<'tcx>,
316 /// Struct returned by `split()`. Note that these are subslices of the
317 /// parent slice and not canonical substs themselves.
318 struct SplitClosureSubsts<'tcx> {
319 closure_kind_ty: Ty<'tcx>,
320 closure_sig_ty: Ty<'tcx>,
321 upvar_kinds: &'tcx [Kind<'tcx>],
324 impl<'tcx> ClosureSubsts<'tcx> {
325 /// Divides the closure substs into their respective
326 /// components. Single source of truth with respect to the
328 fn split(self, def_id: DefId, tcx: TyCtxt<'_>) -> SplitClosureSubsts<'tcx> {
329 let generics = tcx.generics_of(def_id);
330 let parent_len = generics.parent_count;
332 closure_kind_ty: self.substs.type_at(parent_len),
333 closure_sig_ty: self.substs.type_at(parent_len + 1),
334 upvar_kinds: &self.substs[parent_len + 2..],
343 ) -> 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>) -> 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>) -> 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
432 ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
433 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
434 upvar_kinds.iter().map(|t| {
435 if let UnpackedKind::Type(ty) = t.unpack() {
438 bug!("upvar should be type")
443 /// Returns the type representing the yield type of the generator.
444 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
445 self.split(def_id, tcx).yield_ty
448 /// Returns the type representing the return type of the generator.
449 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
450 self.split(def_id, tcx).return_ty
453 /// Returns the "generator signature", which consists of its yield
454 /// and return types.
456 /// N.B., some bits of the code prefers to see this wrapped in a
457 /// binder, but it never contains bound regions. Probably this
458 /// function should be removed.
459 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_>) -> PolyGenSig<'tcx> {
460 ty::Binder::dummy(self.sig(def_id, tcx))
463 /// Returns the "generator signature", which consists of its yield
464 /// and return types.
465 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_>) -> GenSig<'tcx> {
467 yield_ty: self.yield_ty(def_id, tcx),
468 return_ty: self.return_ty(def_id, tcx),
473 impl<'tcx> GeneratorSubsts<'tcx> {
474 /// Generator have not been resumed yet
475 pub const UNRESUMED: usize = 0;
476 /// Generator has returned / is completed
477 pub const RETURNED: usize = 1;
478 /// Generator has been poisoned
479 pub const POISONED: usize = 2;
481 const UNRESUMED_NAME: &'static str = "Unresumed";
482 const RETURNED_NAME: &'static str = "Returned";
483 const POISONED_NAME: &'static str = "Panicked";
485 /// The valid variant indices of this Generator.
487 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
488 // FIXME requires optimized MIR
489 let num_variants = tcx.generator_layout(def_id).variant_fields.len();
490 (VariantIdx::new(0)..VariantIdx::new(num_variants))
493 /// The discriminant for the given variant. Panics if the variant_index is
496 pub fn discriminant_for_variant(
500 variant_index: VariantIdx,
502 // Generators don't support explicit discriminant values, so they are
503 // the same as the variant index.
504 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
505 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
508 /// The set of all discriminants for the Generator, enumerated with their
511 pub fn discriminants(
515 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
516 self.variant_range(def_id, tcx).map(move |index| {
517 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
521 /// Calls `f` with a reference to the name of the enumerator for the given
524 pub fn variant_name(&self, v: VariantIdx) -> Cow<'static, str> {
526 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
527 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
528 Self::POISONED => Cow::from(Self::POISONED_NAME),
529 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3))
533 /// The type of the state discriminant used in the generator type.
535 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
539 /// This returns the types of the MIR locals which had to be stored across suspension points.
540 /// It is calculated in rustc_mir::transform::generator::StateTransform.
541 /// All the types here must be in the tuple in GeneratorInterior.
543 /// The locals are grouped by their variant number. Note that some locals may
544 /// be repeated in multiple variants.
550 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
551 let layout = tcx.generator_layout(def_id);
552 layout.variant_fields.iter().map(move |variant| {
553 variant.iter().map(move |field| {
554 layout.field_tys[*field].subst(tcx, self.substs)
559 /// This is the types of the fields of a generator which are not stored in a
562 pub fn prefix_tys(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> impl Iterator<Item = Ty<'tcx>> {
563 self.upvar_tys(def_id, tcx)
567 #[derive(Debug, Copy, Clone)]
568 pub enum UpvarSubsts<'tcx> {
569 Closure(ClosureSubsts<'tcx>),
570 Generator(GeneratorSubsts<'tcx>),
573 impl<'tcx> UpvarSubsts<'tcx> {
579 ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
580 let upvar_kinds = match self {
581 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
582 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
584 upvar_kinds.iter().map(|t| {
585 if let UnpackedKind::Type(ty) = t.unpack() {
588 bug!("upvar should be type")
594 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash,
595 RustcEncodable, RustcDecodable, HashStable)]
596 pub enum ExistentialPredicate<'tcx> {
597 /// E.g., `Iterator`.
598 Trait(ExistentialTraitRef<'tcx>),
599 /// E.g., `Iterator::Item = T`.
600 Projection(ExistentialProjection<'tcx>),
605 impl<'tcx> ExistentialPredicate<'tcx> {
606 /// Compares via an ordering that will not change if modules are reordered or other changes are
607 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
608 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
609 use self::ExistentialPredicate::*;
610 match (*self, *other) {
611 (Trait(_), Trait(_)) => Ordering::Equal,
612 (Projection(ref a), Projection(ref b)) =>
613 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
614 (AutoTrait(ref a), AutoTrait(ref b)) =>
615 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
616 (Trait(_), _) => Ordering::Less,
617 (Projection(_), Trait(_)) => Ordering::Greater,
618 (Projection(_), _) => Ordering::Less,
619 (AutoTrait(_), _) => Ordering::Greater,
624 impl<'tcx> Binder<ExistentialPredicate<'tcx>> {
625 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
626 use crate::ty::ToPredicate;
627 match *self.skip_binder() {
628 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
629 ExistentialPredicate::Projection(p) =>
630 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
631 ExistentialPredicate::AutoTrait(did) => {
632 let trait_ref = Binder(ty::TraitRef {
634 substs: tcx.mk_substs_trait(self_ty, &[]),
636 trait_ref.to_predicate()
642 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
644 impl<'tcx> List<ExistentialPredicate<'tcx>> {
645 /// Returns the "principal def id" of this set of existential predicates.
647 /// A Rust trait object type consists (in addition to a lifetime bound)
648 /// of a set of trait bounds, which are separated into any number
649 /// of auto-trait bounds, and at most 1 non-auto-trait bound. The
650 /// non-auto-trait bound is called the "principal" of the trait
653 /// Only the principal can have methods or type parameters (because
654 /// auto traits can have neither of them). This is important, because
655 /// it means the auto traits can be treated as an unordered set (methods
656 /// would force an order for the vtable, while relating traits with
657 /// type parameters without knowing the order to relate them in is
658 /// a rather non-trivial task).
660 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
661 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
662 /// are the set `{Sync}`.
664 /// It is also possible to have a "trivial" trait object that
665 /// consists only of auto traits, with no principal - for example,
666 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
667 /// is `{Send, Sync}`, while there is no principal. These trait objects
668 /// have a "trivial" vtable consisting of just the size, alignment,
670 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
672 ExistentialPredicate::Trait(tr) => Some(tr),
677 pub fn principal_def_id(&self) -> Option<DefId> {
678 self.principal().map(|d| d.def_id)
682 pub fn projection_bounds<'a>(&'a self) ->
683 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
684 self.iter().filter_map(|predicate| {
686 ExistentialPredicate::Projection(p) => Some(p),
693 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
694 self.iter().filter_map(|predicate| {
696 ExistentialPredicate::AutoTrait(d) => Some(d),
703 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
704 pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> {
705 self.skip_binder().principal().map(Binder::bind)
708 pub fn principal_def_id(&self) -> Option<DefId> {
709 self.skip_binder().principal_def_id()
713 pub fn projection_bounds<'a>(&'a self) ->
714 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
715 self.skip_binder().projection_bounds().map(Binder::bind)
719 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
720 self.skip_binder().auto_traits()
723 pub fn iter<'a>(&'a self)
724 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
725 self.skip_binder().iter().cloned().map(Binder::bind)
729 /// A complete reference to a trait. These take numerous guises in syntax,
730 /// but perhaps the most recognizable form is in a where-clause:
734 /// This would be represented by a trait-reference where the `DefId` is the
735 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
736 /// and `U` as parameter 1.
738 /// Trait references also appear in object types like `Foo<U>`, but in
739 /// that case the `Self` parameter is absent from the substitutions.
741 /// Note that a `TraitRef` introduces a level of region binding, to
742 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
743 /// or higher-ranked object types.
744 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
745 pub struct TraitRef<'tcx> {
747 pub substs: SubstsRef<'tcx>,
750 impl<'tcx> TraitRef<'tcx> {
751 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
752 TraitRef { def_id: def_id, substs: substs }
755 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
756 /// are the parameters defined on trait.
757 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> {
760 substs: InternalSubsts::identity_for_item(tcx, def_id),
765 pub fn self_ty(&self) -> Ty<'tcx> {
766 self.substs.type_at(0)
769 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
770 // Select only the "input types" from a trait-reference. For
771 // now this is all the types that appear in the
772 // trait-reference, but it should eventually exclude
780 substs: SubstsRef<'tcx>,
781 ) -> ty::TraitRef<'tcx> {
782 let defs = tcx.generics_of(trait_id);
786 substs: tcx.intern_substs(&substs[..defs.params.len()])
791 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
793 impl<'tcx> PolyTraitRef<'tcx> {
794 pub fn self_ty(&self) -> Ty<'tcx> {
795 self.skip_binder().self_ty()
798 pub fn def_id(&self) -> DefId {
799 self.skip_binder().def_id
802 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
803 // Note that we preserve binding levels
804 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
808 /// An existential reference to a trait, where `Self` is erased.
809 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
811 /// exists T. T: Trait<'a, 'b, X, Y>
813 /// The substitutions don't include the erased `Self`, only trait
814 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
815 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
816 RustcEncodable, RustcDecodable, HashStable)]
817 pub struct ExistentialTraitRef<'tcx> {
819 pub substs: SubstsRef<'tcx>,
822 impl<'tcx> ExistentialTraitRef<'tcx> {
823 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
824 // Select only the "input types" from a trait-reference. For
825 // now this is all the types that appear in the
826 // trait-reference, but it should eventually exclude
831 pub fn erase_self_ty(
833 trait_ref: ty::TraitRef<'tcx>,
834 ) -> ty::ExistentialTraitRef<'tcx> {
835 // Assert there is a Self.
836 trait_ref.substs.type_at(0);
838 ty::ExistentialTraitRef {
839 def_id: trait_ref.def_id,
840 substs: tcx.intern_substs(&trait_ref.substs[1..])
844 /// Object types don't have a self type specified. Therefore, when
845 /// we convert the principal trait-ref into a normal trait-ref,
846 /// you must give *some* self type. A common choice is `mk_err()`
847 /// or some placeholder type.
848 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
849 // otherwise the escaping vars would be captured by the binder
850 // debug_assert!(!self_ty.has_escaping_bound_vars());
854 substs: tcx.mk_substs_trait(self_ty, self.substs)
859 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
861 impl<'tcx> PolyExistentialTraitRef<'tcx> {
862 pub fn def_id(&self) -> DefId {
863 self.skip_binder().def_id
866 /// Object types don't have a self type specified. Therefore, when
867 /// we convert the principal trait-ref into a normal trait-ref,
868 /// you must give *some* self type. A common choice is `mk_err()`
869 /// or some placeholder type.
870 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
871 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
875 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
876 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
877 /// (which would be represented by the type `PolyTraitRef ==
878 /// Binder<TraitRef>`). Note that when we instantiate,
879 /// erase, or otherwise "discharge" these bound vars, we change the
880 /// type from `Binder<T>` to just `T` (see
881 /// e.g., `liberate_late_bound_regions`).
882 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
883 pub struct Binder<T>(T);
886 /// Wraps `value` in a binder, asserting that `value` does not
887 /// contain any bound vars that would be bound by the
888 /// binder. This is commonly used to 'inject' a value T into a
889 /// different binding level.
890 pub fn dummy<'tcx>(value: T) -> Binder<T>
891 where T: TypeFoldable<'tcx>
893 debug_assert!(!value.has_escaping_bound_vars());
897 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
898 pub fn bind(value: T) -> Binder<T> {
902 /// Skips the binder and returns the "bound" value. This is a
903 /// risky thing to do because it's easy to get confused about
904 /// De Bruijn indices and the like. It is usually better to
905 /// discharge the binder using `no_bound_vars` or
906 /// `replace_late_bound_regions` or something like
907 /// that. `skip_binder` is only valid when you are either
908 /// extracting data that has nothing to do with bound vars, you
909 /// are doing some sort of test that does not involve bound
910 /// regions, or you are being very careful about your depth
913 /// Some examples where `skip_binder` is reasonable:
915 /// - extracting the `DefId` from a PolyTraitRef;
916 /// - comparing the self type of a PolyTraitRef to see if it is equal to
917 /// a type parameter `X`, since the type `X` does not reference any regions
918 pub fn skip_binder(&self) -> &T {
922 pub fn as_ref(&self) -> Binder<&T> {
926 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
927 where F: FnOnce(&T) -> U
929 self.as_ref().map_bound(f)
932 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
933 where F: FnOnce(T) -> U
938 /// Unwraps and returns the value within, but only if it contains
939 /// no bound vars at all. (In other words, if this binder --
940 /// and indeed any enclosing binder -- doesn't bind anything at
941 /// all.) Otherwise, returns `None`.
943 /// (One could imagine having a method that just unwraps a single
944 /// binder, but permits late-bound vars bound by enclosing
945 /// binders, but that would require adjusting the debruijn
946 /// indices, and given the shallow binding structure we often use,
947 /// would not be that useful.)
948 pub fn no_bound_vars<'tcx>(self) -> Option<T>
949 where T: TypeFoldable<'tcx>
951 if self.skip_binder().has_escaping_bound_vars() {
954 Some(self.skip_binder().clone())
958 /// Given two things that have the same binder level,
959 /// and an operation that wraps on their contents, executes the operation
960 /// and then wraps its result.
962 /// `f` should consider bound regions at depth 1 to be free, and
963 /// anything it produces with bound regions at depth 1 will be
964 /// bound in the resulting return value.
965 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
966 where F: FnOnce(T, U) -> R
968 Binder(f(self.0, u.0))
971 /// Splits the contents into two things that share the same binder
972 /// level as the original, returning two distinct binders.
974 /// `f` should consider bound regions at depth 1 to be free, and
975 /// anything it produces with bound regions at depth 1 will be
976 /// bound in the resulting return values.
977 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
978 where F: FnOnce(T) -> (U, V)
980 let (u, v) = f(self.0);
981 (Binder(u), Binder(v))
985 /// Represents the projection of an associated type. In explicit UFCS
986 /// form this would be written `<T as Trait<..>>::N`.
987 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
988 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
989 pub struct ProjectionTy<'tcx> {
990 /// The parameters of the associated item.
991 pub substs: SubstsRef<'tcx>,
993 /// The `DefId` of the `TraitItem` for the associated type `N`.
995 /// Note that this is not the `DefId` of the `TraitRef` containing this
996 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
997 pub item_def_id: DefId,
1000 impl<'tcx> ProjectionTy<'tcx> {
1001 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
1002 /// associated item named `item_name`.
1003 pub fn from_ref_and_name(
1005 trait_ref: ty::TraitRef<'tcx>,
1007 ) -> ProjectionTy<'tcx> {
1008 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
1009 item.kind == ty::AssocKind::Type &&
1010 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
1014 substs: trait_ref.substs,
1019 /// Extracts the underlying trait reference from this projection.
1020 /// For example, if this is a projection of `<T as Iterator>::Item`,
1021 /// then this function would return a `T: Iterator` trait reference.
1022 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::TraitRef<'tcx> {
1023 let def_id = tcx.associated_item(self.item_def_id).container.id();
1026 substs: self.substs,
1030 pub fn self_ty(&self) -> Ty<'tcx> {
1031 self.substs.type_at(0)
1035 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1036 pub struct GenSig<'tcx> {
1037 pub yield_ty: Ty<'tcx>,
1038 pub return_ty: Ty<'tcx>,
1041 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
1043 impl<'tcx> PolyGenSig<'tcx> {
1044 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
1045 self.map_bound_ref(|sig| sig.yield_ty)
1047 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
1048 self.map_bound_ref(|sig| sig.return_ty)
1052 /// Signature of a function type, which I have arbitrarily
1053 /// decided to use to refer to the input/output types.
1055 /// - `inputs`: is the list of arguments and their modes.
1056 /// - `output`: is the return type.
1057 /// - `c_variadic`: indicates whether this is a C-variadic function.
1058 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
1059 Hash, RustcEncodable, RustcDecodable, HashStable)]
1060 pub struct FnSig<'tcx> {
1061 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1062 pub c_variadic: bool,
1063 pub unsafety: hir::Unsafety,
1067 impl<'tcx> FnSig<'tcx> {
1068 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1069 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1072 pub fn output(&self) -> Ty<'tcx> {
1073 self.inputs_and_output[self.inputs_and_output.len() - 1]
1076 // Create a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible method
1077 fn fake() -> FnSig<'tcx> {
1079 inputs_and_output: List::empty(),
1081 unsafety: hir::Unsafety::Normal,
1082 abi: abi::Abi::Rust,
1087 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
1089 impl<'tcx> PolyFnSig<'tcx> {
1091 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
1092 self.map_bound_ref(|fn_sig| fn_sig.inputs())
1095 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
1096 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1098 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
1099 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1102 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
1103 self.map_bound_ref(|fn_sig| fn_sig.output())
1105 pub fn c_variadic(&self) -> bool {
1106 self.skip_binder().c_variadic
1108 pub fn unsafety(&self) -> hir::Unsafety {
1109 self.skip_binder().unsafety
1111 pub fn abi(&self) -> abi::Abi {
1112 self.skip_binder().abi
1116 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1119 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1120 Hash, RustcEncodable, RustcDecodable, HashStable)]
1121 pub struct ParamTy {
1123 pub name: InternedString,
1126 impl<'tcx> ParamTy {
1127 pub fn new(index: u32, name: InternedString) -> ParamTy {
1128 ParamTy { index, name: name }
1131 pub fn for_self() -> ParamTy {
1132 ParamTy::new(0, kw::SelfUpper.as_interned_str())
1135 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1136 ParamTy::new(def.index, def.name)
1139 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1140 tcx.mk_ty_param(self.index, self.name)
1143 pub fn is_self(&self) -> bool {
1144 // FIXME(#50125): Ignoring `Self` with `index != 0` might lead to weird behavior elsewhere,
1145 // but this should only be possible when using `-Z continue-parse-after-error` like
1146 // `compile-fail/issue-36638.rs`.
1147 self.name.as_symbol() == kw::SelfUpper && self.index == 0
1151 #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable,
1152 Eq, PartialEq, Ord, PartialOrd, HashStable)]
1153 pub struct ParamConst {
1155 pub name: InternedString,
1158 impl<'tcx> ParamConst {
1159 pub fn new(index: u32, name: InternedString) -> ParamConst {
1160 ParamConst { index, name }
1163 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1164 ParamConst::new(def.index, def.name)
1167 pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
1168 tcx.mk_const_param(self.index, self.name, ty)
1173 /// A [De Bruijn index][dbi] is a standard means of representing
1174 /// regions (and perhaps later types) in a higher-ranked setting. In
1175 /// particular, imagine a type like this:
1177 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1180 /// | +------------+ 0 | |
1182 /// +--------------------------------+ 1 |
1184 /// +------------------------------------------+ 0
1186 /// In this type, there are two binders (the outer fn and the inner
1187 /// fn). We need to be able to determine, for any given region, which
1188 /// fn type it is bound by, the inner or the outer one. There are
1189 /// various ways you can do this, but a De Bruijn index is one of the
1190 /// more convenient and has some nice properties. The basic idea is to
1191 /// count the number of binders, inside out. Some examples should help
1192 /// clarify what I mean.
1194 /// Let's start with the reference type `&'b isize` that is the first
1195 /// argument to the inner function. This region `'b` is assigned a De
1196 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1197 /// fn). The region `'a` that appears in the second argument type (`&'a
1198 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1199 /// second-innermost binder". (These indices are written on the arrays
1200 /// in the diagram).
1202 /// What is interesting is that De Bruijn index attached to a particular
1203 /// variable will vary depending on where it appears. For example,
1204 /// the final type `&'a char` also refers to the region `'a` declared on
1205 /// the outermost fn. But this time, this reference is not nested within
1206 /// any other binders (i.e., it is not an argument to the inner fn, but
1207 /// rather the outer one). Therefore, in this case, it is assigned a
1208 /// De Bruijn index of 0, because the innermost binder in that location
1209 /// is the outer fn.
1211 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1212 pub struct DebruijnIndex {
1213 DEBUG_FORMAT = "DebruijnIndex({})",
1214 const INNERMOST = 0,
1218 pub type Region<'tcx> = &'tcx RegionKind;
1220 /// Representation of regions.
1222 /// Unlike types, most region variants are "fictitious", not concrete,
1223 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1224 /// ones representing concrete regions.
1226 /// ## Bound Regions
1228 /// These are regions that are stored behind a binder and must be substituted
1229 /// with some concrete region before being used. There are two kind of
1230 /// bound regions: early-bound, which are bound in an item's `Generics`,
1231 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1232 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1233 /// the likes of `liberate_late_bound_regions`. The distinction exists
1234 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1236 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1237 /// outside their binder, e.g., in types passed to type inference, and
1238 /// should first be substituted (by placeholder regions, free regions,
1239 /// or region variables).
1241 /// ## Placeholder and Free Regions
1243 /// One often wants to work with bound regions without knowing their precise
1244 /// identity. For example, when checking a function, the lifetime of a borrow
1245 /// can end up being assigned to some region parameter. In these cases,
1246 /// it must be ensured that bounds on the region can't be accidentally
1247 /// assumed without being checked.
1249 /// To do this, we replace the bound regions with placeholder markers,
1250 /// which don't satisfy any relation not explicitly provided.
1252 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1253 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1254 /// to be used. These also support explicit bounds: both the internally-stored
1255 /// *scope*, which the region is assumed to outlive, as well as other
1256 /// relations stored in the `FreeRegionMap`. Note that these relations
1257 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1258 /// `resolve_regions_and_report_errors`.
1260 /// When working with higher-ranked types, some region relations aren't
1261 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1262 /// `RePlaceholder` is designed for this purpose. In these contexts,
1263 /// there's also the risk that some inference variable laying around will
1264 /// get unified with your placeholder region: if you want to check whether
1265 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1266 /// with a placeholder region `'%a`, the variable `'_` would just be
1267 /// instantiated to the placeholder region `'%a`, which is wrong because
1268 /// the inference variable is supposed to satisfy the relation
1269 /// *for every value of the placeholder region*. To ensure that doesn't
1270 /// happen, you can use `leak_check`. This is more clearly explained
1271 /// by the [rustc guide].
1273 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1274 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1275 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1276 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1277 pub enum RegionKind {
1278 /// Region bound in a type or fn declaration which will be
1279 /// substituted 'early' -- that is, at the same time when type
1280 /// parameters are substituted.
1281 ReEarlyBound(EarlyBoundRegion),
1283 /// Region bound in a function scope, which will be substituted when the
1284 /// function is called.
1285 ReLateBound(DebruijnIndex, BoundRegion),
1287 /// When checking a function body, the types of all arguments and so forth
1288 /// that refer to bound region parameters are modified to refer to free
1289 /// region parameters.
1292 /// A concrete region naming some statically determined scope
1293 /// (e.g., an expression or sequence of statements) within the
1294 /// current function.
1295 ReScope(region::Scope),
1297 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1300 /// A region variable. Should not exist after typeck.
1303 /// A placeholder region - basically the higher-ranked version of ReFree.
1304 /// Should not exist after typeck.
1305 RePlaceholder(ty::PlaceholderRegion),
1307 /// Empty lifetime is for data that is never accessed.
1308 /// Bottom in the region lattice. We treat ReEmpty somewhat
1309 /// specially; at least right now, we do not generate instances of
1310 /// it during the GLB computations, but rather
1311 /// generate an error instead. This is to improve error messages.
1312 /// The only way to get an instance of ReEmpty is to have a region
1313 /// variable with no constraints.
1316 /// Erased region, used by trait selection, in MIR and during codegen.
1319 /// These are regions bound in the "defining type" for a
1320 /// closure. They are used ONLY as part of the
1321 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1322 /// See `ClosureRegionRequirements` for more details.
1323 ReClosureBound(RegionVid),
1326 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Region<'tcx> {}
1328 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1329 pub struct EarlyBoundRegion {
1332 pub name: InternedString,
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 ConstVid<'tcx> {
1343 pub phantom: PhantomData<&'tcx ()>,
1346 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1351 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1352 pub struct FloatVid {
1357 pub struct RegionVid {
1358 DEBUG_FORMAT = custom,
1362 impl Atom for RegionVid {
1363 fn index(self) -> usize {
1368 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1369 Hash, RustcEncodable, RustcDecodable, HashStable)]
1375 /// A `FreshTy` is one that is generated as a replacement for an
1376 /// unbound type variable. This is convenient for caching etc. See
1377 /// `infer::freshen` for more details.
1384 pub struct BoundVar { .. }
1387 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1388 pub struct BoundTy {
1390 pub kind: BoundTyKind,
1393 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1394 pub enum BoundTyKind {
1396 Param(InternedString),
1399 impl_stable_hash_for!(struct BoundTy { var, kind });
1400 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1402 impl From<BoundVar> for BoundTy {
1403 fn from(var: BoundVar) -> Self {
1406 kind: BoundTyKind::Anon,
1411 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1412 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash,
1413 Debug, RustcEncodable, RustcDecodable, HashStable)]
1414 pub struct ExistentialProjection<'tcx> {
1415 pub item_def_id: DefId,
1416 pub substs: SubstsRef<'tcx>,
1420 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1422 impl<'tcx> ExistentialProjection<'tcx> {
1423 /// Extracts the underlying existential trait reference from this projection.
1424 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1425 /// then this function would return a `exists T. T: Iterator` existential trait
1427 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> {
1428 let def_id = tcx.associated_item(self.item_def_id).container.id();
1429 ty::ExistentialTraitRef{
1431 substs: self.substs,
1435 pub fn with_self_ty(
1439 ) -> ty::ProjectionPredicate<'tcx> {
1440 // otherwise the escaping regions would be captured by the binders
1441 debug_assert!(!self_ty.has_escaping_bound_vars());
1443 ty::ProjectionPredicate {
1444 projection_ty: ty::ProjectionTy {
1445 item_def_id: self.item_def_id,
1446 substs: tcx.mk_substs_trait(self_ty, self.substs),
1453 impl<'tcx> PolyExistentialProjection<'tcx> {
1454 pub fn with_self_ty(
1458 ) -> ty::PolyProjectionPredicate<'tcx> {
1459 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1462 pub fn item_def_id(&self) -> DefId {
1463 return self.skip_binder().item_def_id;
1467 impl DebruijnIndex {
1468 /// Returns the resulting index when this value is moved into
1469 /// `amount` number of new binders. So, e.g., if you had
1471 /// for<'a> fn(&'a x)
1473 /// and you wanted to change it to
1475 /// for<'a> fn(for<'b> fn(&'a x))
1477 /// you would need to shift the index for `'a` into a new binder.
1479 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1480 DebruijnIndex::from_u32(self.as_u32() + amount)
1483 /// Update this index in place by shifting it "in" through
1484 /// `amount` number of binders.
1485 pub fn shift_in(&mut self, amount: u32) {
1486 *self = self.shifted_in(amount);
1489 /// Returns the resulting index when this value is moved out from
1490 /// `amount` number of new binders.
1492 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1493 DebruijnIndex::from_u32(self.as_u32() - amount)
1496 /// Update in place by shifting out from `amount` binders.
1497 pub fn shift_out(&mut self, amount: u32) {
1498 *self = self.shifted_out(amount);
1501 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1502 /// innermost binder. That is, if we have something bound at `to_binder`,
1503 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1504 /// when moving a region out from inside binders:
1507 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1508 /// // Binder: D3 D2 D1 ^^
1511 /// Here, the region `'a` would have the De Bruijn index D3,
1512 /// because it is the bound 3 binders out. However, if we wanted
1513 /// to refer to that region `'a` in the second argument (the `_`),
1514 /// those two binders would not be in scope. In that case, we
1515 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1516 /// De Bruijn index of `'a` to D1 (the innermost binder).
1518 /// If we invoke `shift_out_to_binder` and the region is in fact
1519 /// bound by one of the binders we are shifting out of, that is an
1520 /// error (and should fail an assertion failure).
1521 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1522 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1526 impl_stable_hash_for!(struct DebruijnIndex { private });
1528 /// Region utilities
1530 /// Is this region named by the user?
1531 pub fn has_name(&self) -> bool {
1533 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1534 RegionKind::ReLateBound(_, br) => br.is_named(),
1535 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1536 RegionKind::ReScope(..) => false,
1537 RegionKind::ReStatic => true,
1538 RegionKind::ReVar(..) => false,
1539 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1540 RegionKind::ReEmpty => false,
1541 RegionKind::ReErased => false,
1542 RegionKind::ReClosureBound(..) => false,
1546 pub fn is_late_bound(&self) -> bool {
1548 ty::ReLateBound(..) => true,
1553 pub fn is_placeholder(&self) -> bool {
1555 ty::RePlaceholder(..) => true,
1560 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1562 ty::ReLateBound(debruijn, _) => debruijn >= index,
1567 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1568 /// innermost binder. That is, if we have something bound at `to_binder`,
1569 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1570 /// when moving a region out from inside binders:
1573 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1574 /// // Binder: D3 D2 D1 ^^
1577 /// Here, the region `'a` would have the De Bruijn index D3,
1578 /// because it is the bound 3 binders out. However, if we wanted
1579 /// to refer to that region `'a` in the second argument (the `_`),
1580 /// those two binders would not be in scope. In that case, we
1581 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1582 /// De Bruijn index of `'a` to D1 (the innermost binder).
1584 /// If we invoke `shift_out_to_binder` and the region is in fact
1585 /// bound by one of the binders we are shifting out of, that is an
1586 /// error (and should fail an assertion failure).
1587 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1589 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1590 debruijn.shifted_out_to_binder(to_binder),
1597 pub fn keep_in_local_tcx(&self) -> bool {
1598 if let ty::ReVar(..) = self {
1605 pub fn type_flags(&self) -> TypeFlags {
1606 let mut flags = TypeFlags::empty();
1608 if self.keep_in_local_tcx() {
1609 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1614 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1615 flags = flags | TypeFlags::HAS_RE_INFER;
1617 ty::RePlaceholder(..) => {
1618 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1619 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1621 ty::ReLateBound(..) => {
1622 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1624 ty::ReEarlyBound(..) => {
1625 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1626 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1631 ty::ReScope { .. } => {
1632 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1636 ty::ReClosureBound(..) => {
1637 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1642 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1643 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1646 debug!("type_flags({:?}) = {:?}", self, flags);
1651 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1652 /// For example, consider the regions in this snippet of code:
1656 /// ^^ -- early bound, declared on an impl
1658 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1659 /// ^^ ^^ ^ anonymous, late-bound
1660 /// | early-bound, appears in where-clauses
1661 /// late-bound, appears only in fn args
1666 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1667 /// of the impl, and for all the other highlighted regions, it
1668 /// would return the `DefId` of the function. In other cases (not shown), this
1669 /// function might return the `DefId` of a closure.
1670 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId {
1672 ty::ReEarlyBound(br) => {
1673 tcx.parent(br.def_id).unwrap()
1675 ty::ReFree(fr) => fr.scope,
1676 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1682 impl<'tcx> TyS<'tcx> {
1684 pub fn is_unit(&self) -> bool {
1686 Tuple(ref tys) => tys.is_empty(),
1692 pub fn is_never(&self) -> bool {
1699 /// Checks whether a type is definitely uninhabited. This is
1700 /// conservative: for some types that are uninhabited we return `false`,
1701 /// but we only return `true` for types that are definitely uninhabited.
1702 /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
1703 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1704 /// size, to account for partial initialisation. See #49298 for details.)
1705 pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool {
1706 // FIXME(varkor): we can make this less conversative by substituting concrete
1710 ty::Adt(def, _) if def.is_union() => {
1711 // For now, `union`s are never considered uninhabited.
1714 ty::Adt(def, _) => {
1715 // Any ADT is uninhabited if either:
1716 // (a) It has no variants (i.e. an empty `enum`);
1717 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1718 // one uninhabited field.
1719 def.variants.iter().all(|var| {
1720 var.fields.iter().any(|field| {
1721 tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
1725 ty::Tuple(tys) => tys.iter().any(|ty| {
1726 ty.expect_ty().conservative_is_privately_uninhabited(tcx)
1728 ty::Array(ty, len) => {
1729 match len.assert_usize(tcx) {
1730 // If the array is definitely non-empty, it's uninhabited if
1731 // the type of its elements is uninhabited.
1732 Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
1737 // References to uninitialised memory is valid for any type, including
1738 // uninhabited types, in unsafe code, so we treat all references as
1747 pub fn is_primitive(&self) -> bool {
1749 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1755 pub fn is_ty_var(&self) -> bool {
1757 Infer(TyVar(_)) => true,
1763 pub fn is_ty_infer(&self) -> bool {
1771 pub fn is_phantom_data(&self) -> bool {
1772 if let Adt(def, _) = self.sty {
1773 def.is_phantom_data()
1780 pub fn is_bool(&self) -> bool { self.sty == Bool }
1783 pub fn is_param(&self, index: u32) -> bool {
1785 ty::Param(ref data) => data.index == index,
1791 pub fn is_self(&self) -> bool {
1793 Param(ref p) => p.is_self(),
1799 pub fn is_slice(&self) -> bool {
1801 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1802 Slice(_) | Str => true,
1810 pub fn is_simd(&self) -> bool {
1812 Adt(def, _) => def.repr.simd(),
1817 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1819 Array(ty, _) | Slice(ty) => ty,
1820 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1821 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1825 pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1827 Adt(def, substs) => {
1828 def.non_enum_variant().fields[0].ty(tcx, substs)
1830 _ => bug!("simd_type called on invalid type")
1834 pub fn simd_size(&self, _cx: TyCtxt<'_>) -> usize {
1836 Adt(def, _) => def.non_enum_variant().fields.len(),
1837 _ => bug!("simd_size called on invalid type")
1842 pub fn is_region_ptr(&self) -> bool {
1850 pub fn is_mutable_pointer(&self) -> bool {
1852 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1853 Ref(_, _, hir::Mutability::MutMutable) => true,
1859 pub fn is_unsafe_ptr(&self) -> bool {
1861 RawPtr(_) => return true,
1866 /// Returns `true` if this type is an `Arc<T>`.
1868 pub fn is_arc(&self) -> bool {
1870 Adt(def, _) => def.is_arc(),
1875 /// Returns `true` if this type is an `Rc<T>`.
1877 pub fn is_rc(&self) -> bool {
1879 Adt(def, _) => def.is_rc(),
1885 pub fn is_box(&self) -> bool {
1887 Adt(def, _) => def.is_box(),
1892 /// panics if called on any type other than `Box<T>`
1893 pub fn boxed_ty(&self) -> Ty<'tcx> {
1895 Adt(def, substs) if def.is_box() => substs.type_at(0),
1896 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1900 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1901 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1902 /// contents are abstract to rustc.)
1904 pub fn is_scalar(&self) -> bool {
1906 Bool | Char | Int(_) | Float(_) | Uint(_) |
1907 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1908 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1913 /// Returns `true` if this type is a floating point type.
1915 pub fn is_floating_point(&self) -> bool {
1918 Infer(FloatVar(_)) => true,
1924 pub fn is_trait(&self) -> bool {
1926 Dynamic(..) => true,
1932 pub fn is_enum(&self) -> bool {
1934 Adt(adt_def, _) => {
1942 pub fn is_closure(&self) -> bool {
1944 Closure(..) => true,
1950 pub fn is_generator(&self) -> bool {
1952 Generator(..) => true,
1958 pub fn is_integral(&self) -> bool {
1960 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1966 pub fn is_fresh_ty(&self) -> bool {
1968 Infer(FreshTy(_)) => true,
1974 pub fn is_fresh(&self) -> bool {
1976 Infer(FreshTy(_)) => true,
1977 Infer(FreshIntTy(_)) => true,
1978 Infer(FreshFloatTy(_)) => true,
1984 pub fn is_char(&self) -> bool {
1992 pub fn is_numeric(&self) -> bool {
1993 self.is_integral() || self.is_floating_point()
1997 pub fn is_signed(&self) -> bool {
2005 pub fn is_pointer_sized(&self) -> bool {
2007 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
2013 pub fn is_machine(&self) -> bool {
2015 Int(..) | Uint(..) | Float(..) => true,
2021 pub fn has_concrete_skeleton(&self) -> bool {
2023 Param(_) | Infer(_) | Error => false,
2028 /// Returns the type and mutability of `*ty`.
2030 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2031 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2032 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2034 Adt(def, _) if def.is_box() => {
2036 ty: self.boxed_ty(),
2037 mutbl: hir::MutImmutable,
2040 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
2041 RawPtr(mt) if explicit => Some(mt),
2046 /// Returns the type of `ty[i]`.
2047 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2049 Array(ty, _) | Slice(ty) => Some(ty),
2054 pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2056 FnDef(def_id, substs) => {
2057 tcx.fn_sig(def_id).subst(tcx, substs)
2060 Error => { // ignore errors (#54954)
2061 ty::Binder::dummy(FnSig::fake())
2063 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
2068 pub fn is_fn(&self) -> bool {
2070 FnDef(..) | FnPtr(_) => true,
2076 pub fn is_fn_ptr(&self) -> bool {
2084 pub fn is_impl_trait(&self) -> bool {
2092 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2094 Adt(adt, _) => Some(adt),
2099 /// If the type contains variants, returns the valid range of variant indices.
2100 /// FIXME This requires the optimized MIR in the case of generators.
2102 pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2104 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2105 TyKind::Generator(def_id, substs, _) => Some(substs.variant_range(def_id, tcx)),
2110 /// If the type contains variants, returns the variant for `variant_index`.
2111 /// Panics if `variant_index` is out of range.
2112 /// FIXME This requires the optimized MIR in the case of generators.
2114 pub fn discriminant_for_variant(
2117 variant_index: VariantIdx,
2118 ) -> Option<Discr<'tcx>> {
2120 TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)),
2121 TyKind::Generator(def_id, substs, _) =>
2122 Some(substs.discriminant_for_variant(def_id, tcx, variant_index)),
2127 /// Push onto `out` the regions directly referenced from this type (but not
2128 /// types reachable from this type via `walk_tys`). This ignores late-bound
2129 /// regions binders.
2130 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
2132 Ref(region, _, _) => {
2135 Dynamic(ref obj, region) => {
2137 if let Some(principal) = obj.principal() {
2138 out.extend(principal.skip_binder().substs.regions());
2141 Adt(_, substs) | Opaque(_, substs) => {
2142 out.extend(substs.regions())
2144 Closure(_, ClosureSubsts { ref substs }) |
2145 Generator(_, GeneratorSubsts { ref substs }, _) => {
2146 out.extend(substs.regions())
2148 Projection(ref data) | UnnormalizedProjection(ref data) => {
2149 out.extend(data.substs.regions())
2153 GeneratorWitness(..) |
2174 /// When we create a closure, we record its kind (i.e., what trait
2175 /// it implements) into its `ClosureSubsts` using a type
2176 /// parameter. This is kind of a phantom type, except that the
2177 /// most convenient thing for us to are the integral types. This
2178 /// function converts such a special type into the closure
2179 /// kind. To go the other way, use
2180 /// `tcx.closure_kind_ty(closure_kind)`.
2182 /// Note that during type checking, we use an inference variable
2183 /// to represent the closure kind, because it has not yet been
2184 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2185 /// is complete, that type variable will be unified.
2186 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2188 Int(int_ty) => match int_ty {
2189 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
2190 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2191 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2192 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2197 Error => Some(ty::ClosureKind::Fn),
2199 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2203 /// Fast path helper for testing if a type is `Sized`.
2205 /// Returning true means the type is known to be sized. Returning
2206 /// `false` means nothing -- could be sized, might not be.
2207 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool {
2209 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
2210 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
2211 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
2212 ty::Char | ty::Ref(..) | ty::Generator(..) |
2213 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
2214 ty::Never | ty::Error =>
2217 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2221 tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx))
2224 ty::Adt(def, _substs) =>
2225 def.sized_constraint(tcx).is_empty(),
2227 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2229 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2231 ty::Infer(ty::TyVar(_)) => false,
2234 ty::Placeholder(..) |
2235 ty::Infer(ty::FreshTy(_)) |
2236 ty::Infer(ty::FreshIntTy(_)) |
2237 ty::Infer(ty::FreshFloatTy(_)) =>
2238 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2243 /// Typed constant value.
2244 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable,
2245 Eq, PartialEq, Ord, PartialOrd, HashStable)]
2246 pub struct Const<'tcx> {
2249 pub val: ConstValue<'tcx>,
2252 #[cfg(target_arch = "x86_64")]
2253 static_assert_size!(Const<'_>, 40);
2255 impl<'tcx> Const<'tcx> {
2257 pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
2259 val: ConstValue::Scalar(val),
2265 pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self {
2266 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2267 panic!("could not compute layout for {:?}: {:?}", ty, e)
2269 Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
2273 pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2274 Self::from_scalar(tcx, Scalar::zst(), ty)
2278 pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self {
2279 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2283 pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self {
2284 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2288 pub fn to_bits(&self, tcx: TyCtxt<'tcx>, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> Option<u128> {
2289 if self.ty != ty.value {
2292 let size = tcx.layout_of(ty).ok()?.size;
2293 self.val.try_to_bits(size)
2297 pub fn to_ptr(&self) -> Option<Pointer> {
2298 self.val.try_to_ptr()
2302 pub fn assert_bits(&self, tcx: TyCtxt<'tcx>, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> Option<u128> {
2303 assert_eq!(self.ty, ty.value);
2304 let size = tcx.layout_of(ty).ok()?.size;
2305 self.val.try_to_bits(size)
2309 pub fn assert_bool(&self, tcx: TyCtxt<'tcx>) -> Option<bool> {
2310 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2318 pub fn assert_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64> {
2319 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2323 pub fn unwrap_bits(&self, tcx: TyCtxt<'tcx>, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> u128 {
2324 self.assert_bits(tcx, ty).unwrap_or_else(||
2325 bug!("expected bits of {}, got {:#?}", ty.value, self))
2329 pub fn unwrap_usize(&self, tcx: TyCtxt<'tcx>) -> u64 {
2330 self.assert_usize(tcx).unwrap_or_else(||
2331 bug!("expected constant usize, got {:#?}", self))
2335 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
2337 /// An inference variable for a const, for use in const generics.
2338 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd,
2339 Ord, RustcEncodable, RustcDecodable, Hash, HashStable)]
2340 pub enum InferConst<'tcx> {
2341 /// Infer the value of the const.
2342 Var(ConstVid<'tcx>),
2343 /// A fresh const variable. See `infer::freshen` for more details.
2345 /// Canonicalized const variable, used only when preparing a trait query.
2346 Canonical(DebruijnIndex, BoundVar),