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, GlobalId};
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 `type Foo = impl Trait` 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 one 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
685 self.iter().filter_map(|predicate| {
687 ExistentialPredicate::Projection(p) => Some(p),
694 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
695 self.iter().filter_map(|predicate| {
697 ExistentialPredicate::AutoTrait(d) => Some(d),
704 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
705 pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> {
706 self.skip_binder().principal().map(Binder::bind)
709 pub fn principal_def_id(&self) -> Option<DefId> {
710 self.skip_binder().principal_def_id()
714 pub fn projection_bounds<'a>(&'a self) ->
715 impl Iterator<Item = PolyExistentialProjection<'tcx>> + 'a {
716 self.skip_binder().projection_bounds().map(Binder::bind)
720 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
721 self.skip_binder().auto_traits()
724 pub fn iter<'a>(&'a self)
725 -> impl DoubleEndedIterator<Item = Binder<ExistentialPredicate<'tcx>>> + 'tcx {
726 self.skip_binder().iter().cloned().map(Binder::bind)
730 /// A complete reference to a trait. These take numerous guises in syntax,
731 /// but perhaps the most recognizable form is in a where-clause:
735 /// This would be represented by a trait-reference where the `DefId` is the
736 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
737 /// and `U` as parameter 1.
739 /// Trait references also appear in object types like `Foo<U>`, but in
740 /// that case the `Self` parameter is absent from the substitutions.
742 /// Note that a `TraitRef` introduces a level of region binding, to
743 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
744 /// or higher-ranked object types.
745 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
746 pub struct TraitRef<'tcx> {
748 pub substs: SubstsRef<'tcx>,
751 impl<'tcx> TraitRef<'tcx> {
752 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
753 TraitRef { def_id: def_id, substs: substs }
756 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
757 /// are the parameters defined on trait.
758 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> {
761 substs: InternalSubsts::identity_for_item(tcx, def_id),
766 pub fn self_ty(&self) -> Ty<'tcx> {
767 self.substs.type_at(0)
770 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
771 // Select only the "input types" from a trait-reference. For
772 // now this is all the types that appear in the
773 // trait-reference, but it should eventually exclude
781 substs: SubstsRef<'tcx>,
782 ) -> ty::TraitRef<'tcx> {
783 let defs = tcx.generics_of(trait_id);
787 substs: tcx.intern_substs(&substs[..defs.params.len()])
792 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
794 impl<'tcx> PolyTraitRef<'tcx> {
795 pub fn self_ty(&self) -> Ty<'tcx> {
796 self.skip_binder().self_ty()
799 pub fn def_id(&self) -> DefId {
800 self.skip_binder().def_id
803 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
804 // Note that we preserve binding levels
805 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
809 /// An existential reference to a trait, where `Self` is erased.
810 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
812 /// exists T. T: Trait<'a, 'b, X, Y>
814 /// The substitutions don't include the erased `Self`, only trait
815 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
816 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
817 RustcEncodable, RustcDecodable, HashStable)]
818 pub struct ExistentialTraitRef<'tcx> {
820 pub substs: SubstsRef<'tcx>,
823 impl<'tcx> ExistentialTraitRef<'tcx> {
824 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
825 // Select only the "input types" from a trait-reference. For
826 // now this is all the types that appear in the
827 // trait-reference, but it should eventually exclude
832 pub fn erase_self_ty(
834 trait_ref: ty::TraitRef<'tcx>,
835 ) -> ty::ExistentialTraitRef<'tcx> {
836 // Assert there is a Self.
837 trait_ref.substs.type_at(0);
839 ty::ExistentialTraitRef {
840 def_id: trait_ref.def_id,
841 substs: tcx.intern_substs(&trait_ref.substs[1..])
845 /// Object types don't have a self type specified. Therefore, when
846 /// we convert the principal trait-ref into a normal trait-ref,
847 /// you must give *some* self type. A common choice is `mk_err()`
848 /// or some placeholder type.
849 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
850 // otherwise the escaping vars would be captured by the binder
851 // debug_assert!(!self_ty.has_escaping_bound_vars());
855 substs: tcx.mk_substs_trait(self_ty, self.substs)
860 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
862 impl<'tcx> PolyExistentialTraitRef<'tcx> {
863 pub fn def_id(&self) -> DefId {
864 self.skip_binder().def_id
867 /// Object types don't have a self type specified. Therefore, when
868 /// we convert the principal trait-ref into a normal trait-ref,
869 /// you must give *some* self type. A common choice is `mk_err()`
870 /// or some placeholder type.
871 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
872 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
876 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
877 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
878 /// (which would be represented by the type `PolyTraitRef ==
879 /// Binder<TraitRef>`). Note that when we instantiate,
880 /// erase, or otherwise "discharge" these bound vars, we change the
881 /// type from `Binder<T>` to just `T` (see
882 /// e.g., `liberate_late_bound_regions`).
883 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
884 pub struct Binder<T>(T);
887 /// Wraps `value` in a binder, asserting that `value` does not
888 /// contain any bound vars that would be bound by the
889 /// binder. This is commonly used to 'inject' a value T into a
890 /// different binding level.
891 pub fn dummy<'tcx>(value: T) -> Binder<T>
892 where T: TypeFoldable<'tcx>
894 debug_assert!(!value.has_escaping_bound_vars());
898 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
899 pub fn bind(value: T) -> Binder<T> {
903 /// Skips the binder and returns the "bound" value. This is a
904 /// risky thing to do because it's easy to get confused about
905 /// De Bruijn indices and the like. It is usually better to
906 /// discharge the binder using `no_bound_vars` or
907 /// `replace_late_bound_regions` or something like
908 /// that. `skip_binder` is only valid when you are either
909 /// extracting data that has nothing to do with bound vars, you
910 /// are doing some sort of test that does not involve bound
911 /// regions, or you are being very careful about your depth
914 /// Some examples where `skip_binder` is reasonable:
916 /// - extracting the `DefId` from a PolyTraitRef;
917 /// - comparing the self type of a PolyTraitRef to see if it is equal to
918 /// a type parameter `X`, since the type `X` does not reference any regions
919 pub fn skip_binder(&self) -> &T {
923 pub fn as_ref(&self) -> Binder<&T> {
927 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
928 where F: FnOnce(&T) -> U
930 self.as_ref().map_bound(f)
933 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
934 where F: FnOnce(T) -> U
939 /// Unwraps and returns the value within, but only if it contains
940 /// no bound vars at all. (In other words, if this binder --
941 /// and indeed any enclosing binder -- doesn't bind anything at
942 /// all.) Otherwise, returns `None`.
944 /// (One could imagine having a method that just unwraps a single
945 /// binder, but permits late-bound vars bound by enclosing
946 /// binders, but that would require adjusting the debruijn
947 /// indices, and given the shallow binding structure we often use,
948 /// would not be that useful.)
949 pub fn no_bound_vars<'tcx>(self) -> Option<T>
950 where T: TypeFoldable<'tcx>
952 if self.skip_binder().has_escaping_bound_vars() {
955 Some(self.skip_binder().clone())
959 /// Given two things that have the same binder level,
960 /// and an operation that wraps on their contents, executes the operation
961 /// and then wraps its result.
963 /// `f` should consider bound regions at depth 1 to be free, and
964 /// anything it produces with bound regions at depth 1 will be
965 /// bound in the resulting return value.
966 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
967 where F: FnOnce(T, U) -> R
969 Binder(f(self.0, u.0))
972 /// Splits the contents into two things that share the same binder
973 /// level as the original, returning two distinct binders.
975 /// `f` should consider bound regions at depth 1 to be free, and
976 /// anything it produces with bound regions at depth 1 will be
977 /// bound in the resulting return values.
978 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
979 where F: FnOnce(T) -> (U, V)
981 let (u, v) = f(self.0);
982 (Binder(u), Binder(v))
986 /// Represents the projection of an associated type. In explicit UFCS
987 /// form this would be written `<T as Trait<..>>::N`.
988 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
989 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
990 pub struct ProjectionTy<'tcx> {
991 /// The parameters of the associated item.
992 pub substs: SubstsRef<'tcx>,
994 /// The `DefId` of the `TraitItem` for the associated type `N`.
996 /// Note that this is not the `DefId` of the `TraitRef` containing this
997 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
998 pub item_def_id: DefId,
1001 impl<'tcx> ProjectionTy<'tcx> {
1002 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
1003 /// associated item named `item_name`.
1004 pub fn from_ref_and_name(
1006 trait_ref: ty::TraitRef<'tcx>,
1008 ) -> ProjectionTy<'tcx> {
1009 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
1010 item.kind == ty::AssocKind::Type &&
1011 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
1015 substs: trait_ref.substs,
1020 /// Extracts the underlying trait reference from this projection.
1021 /// For example, if this is a projection of `<T as Iterator>::Item`,
1022 /// then this function would return a `T: Iterator` trait reference.
1023 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::TraitRef<'tcx> {
1024 let def_id = tcx.associated_item(self.item_def_id).container.id();
1027 substs: self.substs,
1031 pub fn self_ty(&self) -> Ty<'tcx> {
1032 self.substs.type_at(0)
1036 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1037 pub struct GenSig<'tcx> {
1038 pub yield_ty: Ty<'tcx>,
1039 pub return_ty: Ty<'tcx>,
1042 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
1044 impl<'tcx> PolyGenSig<'tcx> {
1045 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
1046 self.map_bound_ref(|sig| sig.yield_ty)
1048 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
1049 self.map_bound_ref(|sig| sig.return_ty)
1053 /// Signature of a function type, which I have arbitrarily
1054 /// decided to use to refer to the input/output types.
1056 /// - `inputs`: is the list of arguments and their modes.
1057 /// - `output`: is the return type.
1058 /// - `c_variadic`: indicates whether this is a C-variadic function.
1059 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
1060 Hash, RustcEncodable, RustcDecodable, HashStable)]
1061 pub struct FnSig<'tcx> {
1062 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1063 pub c_variadic: bool,
1064 pub unsafety: hir::Unsafety,
1068 impl<'tcx> FnSig<'tcx> {
1069 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1070 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1073 pub fn output(&self) -> Ty<'tcx> {
1074 self.inputs_and_output[self.inputs_and_output.len() - 1]
1077 // Create a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible method
1078 fn fake() -> FnSig<'tcx> {
1080 inputs_and_output: List::empty(),
1082 unsafety: hir::Unsafety::Normal,
1083 abi: abi::Abi::Rust,
1088 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
1090 impl<'tcx> PolyFnSig<'tcx> {
1092 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
1093 self.map_bound_ref(|fn_sig| fn_sig.inputs())
1096 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
1097 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1099 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
1100 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1103 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
1104 self.map_bound_ref(|fn_sig| fn_sig.output())
1106 pub fn c_variadic(&self) -> bool {
1107 self.skip_binder().c_variadic
1109 pub fn unsafety(&self) -> hir::Unsafety {
1110 self.skip_binder().unsafety
1112 pub fn abi(&self) -> abi::Abi {
1113 self.skip_binder().abi
1117 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1120 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1121 Hash, RustcEncodable, RustcDecodable, HashStable)]
1122 pub struct ParamTy {
1124 pub name: InternedString,
1127 impl<'tcx> ParamTy {
1128 pub fn new(index: u32, name: InternedString) -> ParamTy {
1129 ParamTy { index, name: name }
1132 pub fn for_self() -> ParamTy {
1133 ParamTy::new(0, kw::SelfUpper.as_interned_str())
1136 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1137 ParamTy::new(def.index, def.name)
1140 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1141 tcx.mk_ty_param(self.index, self.name)
1145 #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable,
1146 Eq, PartialEq, Ord, PartialOrd, HashStable)]
1147 pub struct ParamConst {
1149 pub name: InternedString,
1152 impl<'tcx> ParamConst {
1153 pub fn new(index: u32, name: InternedString) -> ParamConst {
1154 ParamConst { index, name }
1157 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1158 ParamConst::new(def.index, def.name)
1161 pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
1162 tcx.mk_const_param(self.index, self.name, ty)
1167 /// A [De Bruijn index][dbi] is a standard means of representing
1168 /// regions (and perhaps later types) in a higher-ranked setting. In
1169 /// particular, imagine a type like this:
1171 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1174 /// | +------------+ 0 | |
1176 /// +--------------------------------+ 1 |
1178 /// +------------------------------------------+ 0
1180 /// In this type, there are two binders (the outer fn and the inner
1181 /// fn). We need to be able to determine, for any given region, which
1182 /// fn type it is bound by, the inner or the outer one. There are
1183 /// various ways you can do this, but a De Bruijn index is one of the
1184 /// more convenient and has some nice properties. The basic idea is to
1185 /// count the number of binders, inside out. Some examples should help
1186 /// clarify what I mean.
1188 /// Let's start with the reference type `&'b isize` that is the first
1189 /// argument to the inner function. This region `'b` is assigned a De
1190 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1191 /// fn). The region `'a` that appears in the second argument type (`&'a
1192 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1193 /// second-innermost binder". (These indices are written on the arrays
1194 /// in the diagram).
1196 /// What is interesting is that De Bruijn index attached to a particular
1197 /// variable will vary depending on where it appears. For example,
1198 /// the final type `&'a char` also refers to the region `'a` declared on
1199 /// the outermost fn. But this time, this reference is not nested within
1200 /// any other binders (i.e., it is not an argument to the inner fn, but
1201 /// rather the outer one). Therefore, in this case, it is assigned a
1202 /// De Bruijn index of 0, because the innermost binder in that location
1203 /// is the outer fn.
1205 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1206 pub struct DebruijnIndex {
1207 DEBUG_FORMAT = "DebruijnIndex({})",
1208 const INNERMOST = 0,
1212 pub type Region<'tcx> = &'tcx RegionKind;
1214 /// Representation of regions.
1216 /// Unlike types, most region variants are "fictitious", not concrete,
1217 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1218 /// ones representing concrete regions.
1220 /// ## Bound Regions
1222 /// These are regions that are stored behind a binder and must be substituted
1223 /// with some concrete region before being used. There are two kind of
1224 /// bound regions: early-bound, which are bound in an item's `Generics`,
1225 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1226 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1227 /// the likes of `liberate_late_bound_regions`. The distinction exists
1228 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1230 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1231 /// outside their binder, e.g., in types passed to type inference, and
1232 /// should first be substituted (by placeholder regions, free regions,
1233 /// or region variables).
1235 /// ## Placeholder and Free Regions
1237 /// One often wants to work with bound regions without knowing their precise
1238 /// identity. For example, when checking a function, the lifetime of a borrow
1239 /// can end up being assigned to some region parameter. In these cases,
1240 /// it must be ensured that bounds on the region can't be accidentally
1241 /// assumed without being checked.
1243 /// To do this, we replace the bound regions with placeholder markers,
1244 /// which don't satisfy any relation not explicitly provided.
1246 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1247 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1248 /// to be used. These also support explicit bounds: both the internally-stored
1249 /// *scope*, which the region is assumed to outlive, as well as other
1250 /// relations stored in the `FreeRegionMap`. Note that these relations
1251 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1252 /// `resolve_regions_and_report_errors`.
1254 /// When working with higher-ranked types, some region relations aren't
1255 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1256 /// `RePlaceholder` is designed for this purpose. In these contexts,
1257 /// there's also the risk that some inference variable laying around will
1258 /// get unified with your placeholder region: if you want to check whether
1259 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1260 /// with a placeholder region `'%a`, the variable `'_` would just be
1261 /// instantiated to the placeholder region `'%a`, which is wrong because
1262 /// the inference variable is supposed to satisfy the relation
1263 /// *for every value of the placeholder region*. To ensure that doesn't
1264 /// happen, you can use `leak_check`. This is more clearly explained
1265 /// by the [rustc guide].
1267 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1268 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1269 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1270 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1271 pub enum RegionKind {
1272 /// Region bound in a type or fn declaration which will be
1273 /// substituted 'early' -- that is, at the same time when type
1274 /// parameters are substituted.
1275 ReEarlyBound(EarlyBoundRegion),
1277 /// Region bound in a function scope, which will be substituted when the
1278 /// function is called.
1279 ReLateBound(DebruijnIndex, BoundRegion),
1281 /// When checking a function body, the types of all arguments and so forth
1282 /// that refer to bound region parameters are modified to refer to free
1283 /// region parameters.
1286 /// A concrete region naming some statically determined scope
1287 /// (e.g., an expression or sequence of statements) within the
1288 /// current function.
1289 ReScope(region::Scope),
1291 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1294 /// A region variable. Should not exist after typeck.
1297 /// A placeholder region - basically the higher-ranked version of ReFree.
1298 /// Should not exist after typeck.
1299 RePlaceholder(ty::PlaceholderRegion),
1301 /// Empty lifetime is for data that is never accessed.
1302 /// Bottom in the region lattice. We treat ReEmpty somewhat
1303 /// specially; at least right now, we do not generate instances of
1304 /// it during the GLB computations, but rather
1305 /// generate an error instead. This is to improve error messages.
1306 /// The only way to get an instance of ReEmpty is to have a region
1307 /// variable with no constraints.
1310 /// Erased region, used by trait selection, in MIR and during codegen.
1313 /// These are regions bound in the "defining type" for a
1314 /// closure. They are used ONLY as part of the
1315 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1316 /// See `ClosureRegionRequirements` for more details.
1317 ReClosureBound(RegionVid),
1320 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Region<'tcx> {}
1322 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1323 pub struct EarlyBoundRegion {
1326 pub name: InternedString,
1329 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1334 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1335 pub struct ConstVid<'tcx> {
1337 pub phantom: PhantomData<&'tcx ()>,
1340 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1345 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1346 pub struct FloatVid {
1351 pub struct RegionVid {
1352 DEBUG_FORMAT = custom,
1356 impl Atom for RegionVid {
1357 fn index(self) -> usize {
1362 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1363 Hash, RustcEncodable, RustcDecodable, HashStable)]
1369 /// A `FreshTy` is one that is generated as a replacement for an
1370 /// unbound type variable. This is convenient for caching etc. See
1371 /// `infer::freshen` for more details.
1378 pub struct BoundVar { .. }
1381 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1382 pub struct BoundTy {
1384 pub kind: BoundTyKind,
1387 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1388 pub enum BoundTyKind {
1390 Param(InternedString),
1393 impl_stable_hash_for!(struct BoundTy { var, kind });
1394 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1396 impl From<BoundVar> for BoundTy {
1397 fn from(var: BoundVar) -> Self {
1400 kind: BoundTyKind::Anon,
1405 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1406 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash,
1407 Debug, RustcEncodable, RustcDecodable, HashStable)]
1408 pub struct ExistentialProjection<'tcx> {
1409 pub item_def_id: DefId,
1410 pub substs: SubstsRef<'tcx>,
1414 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1416 impl<'tcx> ExistentialProjection<'tcx> {
1417 /// Extracts the underlying existential trait reference from this projection.
1418 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1419 /// then this function would return a `exists T. T: Iterator` existential trait
1421 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> {
1422 let def_id = tcx.associated_item(self.item_def_id).container.id();
1423 ty::ExistentialTraitRef{
1425 substs: self.substs,
1429 pub fn with_self_ty(
1433 ) -> ty::ProjectionPredicate<'tcx> {
1434 // otherwise the escaping regions would be captured by the binders
1435 debug_assert!(!self_ty.has_escaping_bound_vars());
1437 ty::ProjectionPredicate {
1438 projection_ty: ty::ProjectionTy {
1439 item_def_id: self.item_def_id,
1440 substs: tcx.mk_substs_trait(self_ty, self.substs),
1447 impl<'tcx> PolyExistentialProjection<'tcx> {
1448 pub fn with_self_ty(
1452 ) -> ty::PolyProjectionPredicate<'tcx> {
1453 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1456 pub fn item_def_id(&self) -> DefId {
1457 return self.skip_binder().item_def_id;
1461 impl DebruijnIndex {
1462 /// Returns the resulting index when this value is moved into
1463 /// `amount` number of new binders. So, e.g., if you had
1465 /// for<'a> fn(&'a x)
1467 /// and you wanted to change it to
1469 /// for<'a> fn(for<'b> fn(&'a x))
1471 /// you would need to shift the index for `'a` into a new binder.
1473 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1474 DebruijnIndex::from_u32(self.as_u32() + amount)
1477 /// Update this index in place by shifting it "in" through
1478 /// `amount` number of binders.
1479 pub fn shift_in(&mut self, amount: u32) {
1480 *self = self.shifted_in(amount);
1483 /// Returns the resulting index when this value is moved out from
1484 /// `amount` number of new binders.
1486 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1487 DebruijnIndex::from_u32(self.as_u32() - amount)
1490 /// Update in place by shifting out from `amount` binders.
1491 pub fn shift_out(&mut self, amount: u32) {
1492 *self = self.shifted_out(amount);
1495 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1496 /// innermost binder. That is, if we have something bound at `to_binder`,
1497 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1498 /// when moving a region out from inside binders:
1501 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1502 /// // Binder: D3 D2 D1 ^^
1505 /// Here, the region `'a` would have the De Bruijn index D3,
1506 /// because it is the bound 3 binders out. However, if we wanted
1507 /// to refer to that region `'a` in the second argument (the `_`),
1508 /// those two binders would not be in scope. In that case, we
1509 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1510 /// De Bruijn index of `'a` to D1 (the innermost binder).
1512 /// If we invoke `shift_out_to_binder` and the region is in fact
1513 /// bound by one of the binders we are shifting out of, that is an
1514 /// error (and should fail an assertion failure).
1515 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1516 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1520 impl_stable_hash_for!(struct DebruijnIndex { private });
1522 /// Region utilities
1524 /// Is this region named by the user?
1525 pub fn has_name(&self) -> bool {
1527 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1528 RegionKind::ReLateBound(_, br) => br.is_named(),
1529 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1530 RegionKind::ReScope(..) => false,
1531 RegionKind::ReStatic => true,
1532 RegionKind::ReVar(..) => false,
1533 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1534 RegionKind::ReEmpty => false,
1535 RegionKind::ReErased => false,
1536 RegionKind::ReClosureBound(..) => false,
1540 pub fn is_late_bound(&self) -> bool {
1542 ty::ReLateBound(..) => true,
1547 pub fn is_placeholder(&self) -> bool {
1549 ty::RePlaceholder(..) => true,
1554 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1556 ty::ReLateBound(debruijn, _) => debruijn >= index,
1561 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1562 /// innermost binder. That is, if we have something bound at `to_binder`,
1563 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1564 /// when moving a region out from inside binders:
1567 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1568 /// // Binder: D3 D2 D1 ^^
1571 /// Here, the region `'a` would have the De Bruijn index D3,
1572 /// because it is the bound 3 binders out. However, if we wanted
1573 /// to refer to that region `'a` in the second argument (the `_`),
1574 /// those two binders would not be in scope. In that case, we
1575 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1576 /// De Bruijn index of `'a` to D1 (the innermost binder).
1578 /// If we invoke `shift_out_to_binder` and the region is in fact
1579 /// bound by one of the binders we are shifting out of, that is an
1580 /// error (and should fail an assertion failure).
1581 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1583 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1584 debruijn.shifted_out_to_binder(to_binder),
1591 pub fn keep_in_local_tcx(&self) -> bool {
1592 if let ty::ReVar(..) = self {
1599 pub fn type_flags(&self) -> TypeFlags {
1600 let mut flags = TypeFlags::empty();
1602 if self.keep_in_local_tcx() {
1603 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1608 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1609 flags = flags | TypeFlags::HAS_RE_INFER;
1611 ty::RePlaceholder(..) => {
1612 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1613 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1615 ty::ReLateBound(..) => {
1616 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1618 ty::ReEarlyBound(..) => {
1619 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1620 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1625 ty::ReScope { .. } => {
1626 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1630 ty::ReClosureBound(..) => {
1631 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1636 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1637 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1640 debug!("type_flags({:?}) = {:?}", self, flags);
1645 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1646 /// For example, consider the regions in this snippet of code:
1650 /// ^^ -- early bound, declared on an impl
1652 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1653 /// ^^ ^^ ^ anonymous, late-bound
1654 /// | early-bound, appears in where-clauses
1655 /// late-bound, appears only in fn args
1660 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1661 /// of the impl, and for all the other highlighted regions, it
1662 /// would return the `DefId` of the function. In other cases (not shown), this
1663 /// function might return the `DefId` of a closure.
1664 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId {
1666 ty::ReEarlyBound(br) => {
1667 tcx.parent(br.def_id).unwrap()
1669 ty::ReFree(fr) => fr.scope,
1670 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1676 impl<'tcx> TyS<'tcx> {
1678 pub fn is_unit(&self) -> bool {
1680 Tuple(ref tys) => tys.is_empty(),
1686 pub fn is_never(&self) -> bool {
1693 /// Checks whether a type is definitely uninhabited. This is
1694 /// conservative: for some types that are uninhabited we return `false`,
1695 /// but we only return `true` for types that are definitely uninhabited.
1696 /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
1697 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1698 /// size, to account for partial initialisation. See #49298 for details.)
1699 pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool {
1700 // FIXME(varkor): we can make this less conversative by substituting concrete
1704 ty::Adt(def, _) if def.is_union() => {
1705 // For now, `union`s are never considered uninhabited.
1708 ty::Adt(def, _) => {
1709 // Any ADT is uninhabited if either:
1710 // (a) It has no variants (i.e. an empty `enum`);
1711 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1712 // one uninhabited field.
1713 def.variants.iter().all(|var| {
1714 var.fields.iter().any(|field| {
1715 tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
1719 ty::Tuple(tys) => tys.iter().any(|ty| {
1720 ty.expect_ty().conservative_is_privately_uninhabited(tcx)
1722 ty::Array(ty, len) => {
1723 match len.try_eval_usize(tcx, ParamEnv::empty()) {
1724 // If the array is definitely non-empty, it's uninhabited if
1725 // the type of its elements is uninhabited.
1726 Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
1731 // References to uninitialised memory is valid for any type, including
1732 // uninhabited types, in unsafe code, so we treat all references as
1741 pub fn is_primitive(&self) -> bool {
1743 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1749 pub fn is_ty_var(&self) -> bool {
1751 Infer(TyVar(_)) => true,
1757 pub fn is_ty_infer(&self) -> bool {
1765 pub fn is_phantom_data(&self) -> bool {
1766 if let Adt(def, _) = self.sty {
1767 def.is_phantom_data()
1774 pub fn is_bool(&self) -> bool { self.sty == Bool }
1777 pub fn is_param(&self, index: u32) -> bool {
1779 ty::Param(ref data) => data.index == index,
1785 pub fn is_slice(&self) -> bool {
1787 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1788 Slice(_) | Str => true,
1796 pub fn is_simd(&self) -> bool {
1798 Adt(def, _) => def.repr.simd(),
1803 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1805 Array(ty, _) | Slice(ty) => ty,
1806 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1807 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1811 pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1813 Adt(def, substs) => {
1814 def.non_enum_variant().fields[0].ty(tcx, substs)
1816 _ => bug!("simd_type called on invalid type")
1820 pub fn simd_size(&self, _cx: TyCtxt<'_>) -> usize {
1822 Adt(def, _) => def.non_enum_variant().fields.len(),
1823 _ => bug!("simd_size called on invalid type")
1828 pub fn is_region_ptr(&self) -> bool {
1836 pub fn is_mutable_ptr(&self) -> bool {
1838 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1839 Ref(_, _, hir::Mutability::MutMutable) => true,
1845 pub fn is_unsafe_ptr(&self) -> bool {
1847 RawPtr(_) => return true,
1852 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1854 pub fn is_any_ptr(&self) -> bool {
1855 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1858 /// Returns `true` if this type is an `Arc<T>`.
1860 pub fn is_arc(&self) -> bool {
1862 Adt(def, _) => def.is_arc(),
1867 /// Returns `true` if this type is an `Rc<T>`.
1869 pub fn is_rc(&self) -> bool {
1871 Adt(def, _) => def.is_rc(),
1877 pub fn is_box(&self) -> bool {
1879 Adt(def, _) => def.is_box(),
1884 /// panics if called on any type other than `Box<T>`
1885 pub fn boxed_ty(&self) -> Ty<'tcx> {
1887 Adt(def, substs) if def.is_box() => substs.type_at(0),
1888 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1892 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1893 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1894 /// contents are abstract to rustc.)
1896 pub fn is_scalar(&self) -> bool {
1898 Bool | Char | Int(_) | Float(_) | Uint(_) |
1899 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1900 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1905 /// Returns `true` if this type is a floating point type.
1907 pub fn is_floating_point(&self) -> bool {
1910 Infer(FloatVar(_)) => true,
1916 pub fn is_trait(&self) -> bool {
1918 Dynamic(..) => true,
1924 pub fn is_enum(&self) -> bool {
1926 Adt(adt_def, _) => {
1934 pub fn is_closure(&self) -> bool {
1936 Closure(..) => true,
1942 pub fn is_generator(&self) -> bool {
1944 Generator(..) => true,
1950 pub fn is_integral(&self) -> bool {
1952 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1958 pub fn is_fresh_ty(&self) -> bool {
1960 Infer(FreshTy(_)) => true,
1966 pub fn is_fresh(&self) -> bool {
1968 Infer(FreshTy(_)) => true,
1969 Infer(FreshIntTy(_)) => true,
1970 Infer(FreshFloatTy(_)) => true,
1976 pub fn is_char(&self) -> bool {
1984 pub fn is_numeric(&self) -> bool {
1985 self.is_integral() || self.is_floating_point()
1989 pub fn is_signed(&self) -> bool {
1997 pub fn is_ptr_sized_integral(&self) -> bool {
1999 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
2005 pub fn is_machine(&self) -> bool {
2007 Int(..) | Uint(..) | Float(..) => true,
2013 pub fn has_concrete_skeleton(&self) -> bool {
2015 Param(_) | Infer(_) | Error => false,
2020 /// Returns the type and mutability of `*ty`.
2022 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2023 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2024 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2026 Adt(def, _) if def.is_box() => {
2028 ty: self.boxed_ty(),
2029 mutbl: hir::MutImmutable,
2032 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
2033 RawPtr(mt) if explicit => Some(mt),
2038 /// Returns the type of `ty[i]`.
2039 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2041 Array(ty, _) | Slice(ty) => Some(ty),
2046 pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2048 FnDef(def_id, substs) => {
2049 tcx.fn_sig(def_id).subst(tcx, substs)
2052 Error => { // ignore errors (#54954)
2053 ty::Binder::dummy(FnSig::fake())
2055 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
2060 pub fn is_fn(&self) -> bool {
2062 FnDef(..) | FnPtr(_) => true,
2068 pub fn is_fn_ptr(&self) -> bool {
2076 pub fn is_impl_trait(&self) -> bool {
2084 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2086 Adt(adt, _) => Some(adt),
2091 /// If the type contains variants, returns the valid range of variant indices.
2092 /// FIXME This requires the optimized MIR in the case of generators.
2094 pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2096 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2097 TyKind::Generator(def_id, substs, _) => Some(substs.variant_range(def_id, tcx)),
2102 /// If the type contains variants, returns the variant for `variant_index`.
2103 /// Panics if `variant_index` is out of range.
2104 /// FIXME This requires the optimized MIR in the case of generators.
2106 pub fn discriminant_for_variant(
2109 variant_index: VariantIdx,
2110 ) -> Option<Discr<'tcx>> {
2112 TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)),
2113 TyKind::Generator(def_id, substs, _) =>
2114 Some(substs.discriminant_for_variant(def_id, tcx, variant_index)),
2119 /// Push onto `out` the regions directly referenced from this type (but not
2120 /// types reachable from this type via `walk_tys`). This ignores late-bound
2121 /// regions binders.
2122 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
2124 Ref(region, _, _) => {
2127 Dynamic(ref obj, region) => {
2129 if let Some(principal) = obj.principal() {
2130 out.extend(principal.skip_binder().substs.regions());
2133 Adt(_, substs) | Opaque(_, substs) => {
2134 out.extend(substs.regions())
2136 Closure(_, ClosureSubsts { ref substs }) |
2137 Generator(_, GeneratorSubsts { ref substs }, _) => {
2138 out.extend(substs.regions())
2140 Projection(ref data) | UnnormalizedProjection(ref data) => {
2141 out.extend(data.substs.regions())
2145 GeneratorWitness(..) |
2166 /// When we create a closure, we record its kind (i.e., what trait
2167 /// it implements) into its `ClosureSubsts` using a type
2168 /// parameter. This is kind of a phantom type, except that the
2169 /// most convenient thing for us to are the integral types. This
2170 /// function converts such a special type into the closure
2171 /// kind. To go the other way, use
2172 /// `tcx.closure_kind_ty(closure_kind)`.
2174 /// Note that during type checking, we use an inference variable
2175 /// to represent the closure kind, because it has not yet been
2176 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2177 /// is complete, that type variable will be unified.
2178 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2180 Int(int_ty) => match int_ty {
2181 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
2182 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2183 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2184 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2189 Error => Some(ty::ClosureKind::Fn),
2191 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2195 /// Fast path helper for testing if a type is `Sized`.
2197 /// Returning true means the type is known to be sized. Returning
2198 /// `false` means nothing -- could be sized, might not be.
2199 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool {
2201 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
2202 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
2203 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
2204 ty::Char | ty::Ref(..) | ty::Generator(..) |
2205 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
2206 ty::Never | ty::Error =>
2209 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2213 tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx))
2216 ty::Adt(def, _substs) =>
2217 def.sized_constraint(tcx).is_empty(),
2219 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2221 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2223 ty::Infer(ty::TyVar(_)) => false,
2226 ty::Placeholder(..) |
2227 ty::Infer(ty::FreshTy(_)) |
2228 ty::Infer(ty::FreshIntTy(_)) |
2229 ty::Infer(ty::FreshFloatTy(_)) =>
2230 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2235 /// Typed constant value.
2236 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable,
2237 Eq, PartialEq, Ord, PartialOrd, HashStable)]
2238 pub struct Const<'tcx> {
2241 pub val: ConstValue<'tcx>,
2244 #[cfg(target_arch = "x86_64")]
2245 static_assert_size!(Const<'_>, 40);
2247 impl<'tcx> Const<'tcx> {
2249 pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
2251 val: ConstValue::Scalar(val),
2257 pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self {
2258 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2259 panic!("could not compute layout for {:?}: {:?}", ty, e)
2261 Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
2265 pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2266 Self::from_scalar(tcx, Scalar::zst(), ty)
2270 pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self {
2271 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2275 pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self {
2276 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2280 pub fn try_eval_bits(
2283 param_env: ParamEnv<'tcx>,
2286 assert_eq!(self.ty, ty);
2287 // if `ty` does not depend on generic parameters, use an empty param_env
2288 let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
2290 // FIXME(const_generics): this doesn't work right now,
2291 // because it tries to relate an `Infer` to a `Param`.
2292 ConstValue::Unevaluated(did, substs) => {
2293 // if `substs` has no unresolved components, use and empty param_env
2294 let (param_env, substs) = param_env.with_reveal_all().and(substs).into_parts();
2295 // try to resolve e.g. associated constants to their definition on an impl
2296 let instance = ty::Instance::resolve(tcx, param_env, did, substs)?;
2297 let gid = GlobalId {
2301 let evaluated = tcx.const_eval(param_env.and(gid)).ok()?;
2302 evaluated.val.try_to_bits(size)
2304 // otherwise just extract a `ConstValue`'s bits if possible
2305 _ => self.val.try_to_bits(size),
2310 pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
2311 self.try_eval_bits(tcx, param_env, tcx.types.bool).and_then(|v| match v {
2319 pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> {
2320 self.try_eval_bits(tcx, param_env, tcx.types.usize).map(|v| v as u64)
2324 pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
2325 self.try_eval_bits(tcx, param_env, ty).unwrap_or_else(||
2326 bug!("expected bits of {:#?}, got {:#?}", ty, self))
2330 pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 {
2331 self.eval_bits(tcx, param_env, tcx.types.usize) as u64
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),