1 //! This module contains `TyKind` and its major components.
3 #![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 /// Use `TyS::tuple_fields` to iterate over the field types.
175 Tuple(SubstsRef<'tcx>),
177 /// The projection of an associated type. For example,
178 /// `<T as Trait<..>>::N`.
179 Projection(ProjectionTy<'tcx>),
181 /// A placeholder type used when we do not have enough information
182 /// to normalize the projection of an associated type to an
183 /// existing concrete type. Currently only used with chalk-engine.
184 UnnormalizedProjection(ProjectionTy<'tcx>),
186 /// Opaque (`impl Trait`) type found in a return type.
187 /// The `DefId` comes either from
188 /// * the `impl Trait` ast::Ty node,
189 /// * or the `type Foo = impl Trait` declaration
190 /// The substitutions are for the generics of the function in question.
191 /// After typeck, the concrete type can be found in the `types` map.
192 Opaque(DefId, SubstsRef<'tcx>),
194 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
197 /// Bound type variable, used only when preparing a trait query.
198 Bound(ty::DebruijnIndex, BoundTy),
200 /// A placeholder type - universally quantified higher-ranked type.
201 Placeholder(ty::PlaceholderType),
203 /// A type variable used during type checking.
206 /// A placeholder for a type which could not be computed; this is
207 /// propagated to avoid useless error messages.
211 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
212 #[cfg(target_arch = "x86_64")]
213 static_assert_size!(TyKind<'_>, 24);
215 /// A closure can be modeled as a struct that looks like:
217 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
225 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
226 /// in scope on the function that defined the closure,
227 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
228 /// is rather hackily encoded via a scalar type. See
229 /// `TyS::to_opt_closure_kind` for details.
230 /// - CS represents the *closure signature*, representing as a `fn()`
231 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
232 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
234 /// - U0...Uk are type parameters representing the types of its upvars
235 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
236 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
238 /// So, for example, given this function:
240 /// fn foo<'a, T>(data: &'a mut T) {
241 /// do(|| data.count += 1)
244 /// the type of the closure would be something like:
246 /// struct Closure<'a, T, U0> {
250 /// Note that the type of the upvar is not specified in the struct.
251 /// You may wonder how the impl would then be able to use the upvar,
252 /// if it doesn't know it's type? The answer is that the impl is
253 /// (conceptually) not fully generic over Closure but rather tied to
254 /// instances with the expected upvar types:
256 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
260 /// You can see that the *impl* fully specified the type of the upvar
261 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
262 /// (Here, I am assuming that `data` is mut-borrowed.)
264 /// Now, the last question you may ask is: Why include the upvar types
265 /// as extra type parameters? The reason for this design is that the
266 /// upvar types can reference lifetimes that are internal to the
267 /// creating function. In my example above, for example, the lifetime
268 /// `'b` represents the scope of the closure itself; this is some
269 /// subset of `foo`, probably just the scope of the call to the to
270 /// `do()`. If we just had the lifetime/type parameters from the
271 /// enclosing function, we couldn't name this lifetime `'b`. Note that
272 /// there can also be lifetimes in the types of the upvars themselves,
273 /// if one of them happens to be a reference to something that the
274 /// creating fn owns.
276 /// OK, you say, so why not create a more minimal set of parameters
277 /// that just includes the extra lifetime parameters? The answer is
278 /// primarily that it would be hard --- we don't know at the time when
279 /// we create the closure type what the full types of the upvars are,
280 /// nor do we know which are borrowed and which are not. In this
281 /// design, we can just supply a fresh type parameter and figure that
284 /// All right, you say, but why include the type parameters from the
285 /// original function then? The answer is that codegen may need them
286 /// when monomorphizing, and they may not appear in the upvars. A
287 /// closure could capture no variables but still make use of some
288 /// in-scope type parameter with a bound (e.g., if our example above
289 /// had an extra `U: Default`, and the closure called `U::default()`).
291 /// There is another reason. This design (implicitly) prohibits
292 /// closures from capturing themselves (except via a trait
293 /// object). This simplifies closure inference considerably, since it
294 /// means that when we infer the kind of a closure or its upvars, we
295 /// don't have to handle cycles where the decisions we make for
296 /// closure C wind up influencing the decisions we ought to make for
297 /// closure C (which would then require fixed point iteration to
298 /// handle). Plus it fixes an ICE. :P
302 /// Generators are handled similarly in `GeneratorSubsts`. The set of
303 /// type parameters is similar, but the role of CK and CS are
304 /// different. CK represents the "yield type" and CS represents the
305 /// "return type" of the generator.
306 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
307 Debug, RustcEncodable, RustcDecodable, HashStable)]
308 pub struct ClosureSubsts<'tcx> {
309 /// Lifetime and type parameters from the enclosing function,
310 /// concatenated with the types of the upvars.
312 /// These are separated out because codegen wants to pass them around
313 /// when monomorphizing.
314 pub substs: SubstsRef<'tcx>,
317 /// Struct returned by `split()`. Note that these are subslices of the
318 /// parent slice and not canonical substs themselves.
319 struct SplitClosureSubsts<'tcx> {
320 closure_kind_ty: Ty<'tcx>,
321 closure_sig_ty: Ty<'tcx>,
322 upvar_kinds: &'tcx [Kind<'tcx>],
325 impl<'tcx> ClosureSubsts<'tcx> {
326 /// Divides the closure substs into their respective
327 /// components. Single source of truth with respect to the
329 fn split(self, def_id: DefId, tcx: TyCtxt<'_>) -> SplitClosureSubsts<'tcx> {
330 let generics = tcx.generics_of(def_id);
331 let parent_len = generics.parent_count;
333 closure_kind_ty: self.substs.type_at(parent_len),
334 closure_sig_ty: self.substs.type_at(parent_len + 1),
335 upvar_kinds: &self.substs[parent_len + 2..],
344 ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
345 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
346 upvar_kinds.iter().map(|t| {
347 if let UnpackedKind::Type(ty) = t.unpack() {
350 bug!("upvar should be type")
355 /// Returns the closure kind for this closure; may return a type
356 /// variable during inference. To get the closure kind during
357 /// inference, use `infcx.closure_kind(def_id, substs)`.
358 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
359 self.split(def_id, tcx).closure_kind_ty
362 /// Returns the type representing the closure signature for this
363 /// closure; may contain type variables during inference. To get
364 /// the closure signature during inference, use
365 /// `infcx.fn_sig(def_id)`.
366 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
367 self.split(def_id, tcx).closure_sig_ty
370 /// Returns the closure kind for this closure; only usable outside
371 /// of an inference context, because in that context we know that
372 /// there are no type variables.
374 /// If you have an inference context, use `infcx.closure_kind()`.
375 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> ty::ClosureKind {
376 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
379 /// Extracts the signature from the closure; only usable outside
380 /// of an inference context, because in that context we know that
381 /// there are no type variables.
383 /// If you have an inference context, use `infcx.closure_sig()`.
384 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> ty::PolyFnSig<'tcx> {
385 let ty = self.closure_sig_ty(def_id, tcx);
387 ty::FnPtr(sig) => sig,
388 _ => bug!("closure_sig_ty is not a fn-ptr: {:?}", ty.sty),
393 /// Similar to `ClosureSubsts`; see the above documentation for more.
394 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug,
395 RustcEncodable, RustcDecodable, HashStable)]
396 pub struct GeneratorSubsts<'tcx> {
397 pub substs: SubstsRef<'tcx>,
400 struct SplitGeneratorSubsts<'tcx> {
404 upvar_kinds: &'tcx [Kind<'tcx>],
407 impl<'tcx> GeneratorSubsts<'tcx> {
408 fn split(self, def_id: DefId, tcx: TyCtxt<'_>) -> SplitGeneratorSubsts<'tcx> {
409 let generics = tcx.generics_of(def_id);
410 let parent_len = generics.parent_count;
411 SplitGeneratorSubsts {
412 yield_ty: self.substs.type_at(parent_len),
413 return_ty: self.substs.type_at(parent_len + 1),
414 witness: self.substs.type_at(parent_len + 2),
415 upvar_kinds: &self.substs[parent_len + 3..],
419 /// This describes the types that can be contained in a generator.
420 /// It will be a type variable initially and unified in the last stages of typeck of a body.
421 /// It contains a tuple of all the types that could end up on a generator frame.
422 /// The state transformation MIR pass may only produce layouts which mention types
423 /// in this tuple. Upvars are not counted here.
424 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
425 self.split(def_id, tcx).witness
433 ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
434 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
435 upvar_kinds.iter().map(|t| {
436 if let UnpackedKind::Type(ty) = t.unpack() {
439 bug!("upvar should be type")
444 /// Returns the type representing the yield type of the generator.
445 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
446 self.split(def_id, tcx).yield_ty
449 /// Returns the type representing the return type of the generator.
450 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_>) -> Ty<'tcx> {
451 self.split(def_id, tcx).return_ty
454 /// Returns the "generator signature", which consists of its yield
455 /// and return types.
457 /// N.B., some bits of the code prefers to see this wrapped in a
458 /// binder, but it never contains bound regions. Probably this
459 /// function should be removed.
460 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_>) -> PolyGenSig<'tcx> {
461 ty::Binder::dummy(self.sig(def_id, tcx))
464 /// Returns the "generator signature", which consists of its yield
465 /// and return types.
466 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_>) -> GenSig<'tcx> {
468 yield_ty: self.yield_ty(def_id, tcx),
469 return_ty: self.return_ty(def_id, tcx),
474 impl<'tcx> GeneratorSubsts<'tcx> {
475 /// Generator have not been resumed yet
476 pub const UNRESUMED: usize = 0;
477 /// Generator has returned / is completed
478 pub const RETURNED: usize = 1;
479 /// Generator has been poisoned
480 pub const POISONED: usize = 2;
482 const UNRESUMED_NAME: &'static str = "Unresumed";
483 const RETURNED_NAME: &'static str = "Returned";
484 const POISONED_NAME: &'static str = "Panicked";
486 /// The valid variant indices of this Generator.
488 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
489 // FIXME requires optimized MIR
490 let num_variants = tcx.generator_layout(def_id).variant_fields.len();
491 (VariantIdx::new(0)..VariantIdx::new(num_variants))
494 /// The discriminant for the given variant. Panics if the variant_index is
497 pub fn discriminant_for_variant(
501 variant_index: VariantIdx,
503 // Generators don't support explicit discriminant values, so they are
504 // the same as the variant index.
505 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
506 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
509 /// The set of all discriminants for the Generator, enumerated with their
512 pub fn discriminants(
516 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
517 self.variant_range(def_id, tcx).map(move |index| {
518 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
522 /// Calls `f` with a reference to the name of the enumerator for the given
525 pub fn variant_name(&self, v: VariantIdx) -> Cow<'static, str> {
527 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
528 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
529 Self::POISONED => Cow::from(Self::POISONED_NAME),
530 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3))
534 /// The type of the state discriminant used in the generator type.
536 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
540 /// This returns the types of the MIR locals which had to be stored across suspension points.
541 /// It is calculated in rustc_mir::transform::generator::StateTransform.
542 /// All the types here must be in the tuple in GeneratorInterior.
544 /// The locals are grouped by their variant number. Note that some locals may
545 /// be repeated in multiple variants.
551 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
552 let layout = tcx.generator_layout(def_id);
553 layout.variant_fields.iter().map(move |variant| {
554 variant.iter().map(move |field| {
555 layout.field_tys[*field].subst(tcx, self.substs)
560 /// This is the types of the fields of a generator which are not stored in a
563 pub fn prefix_tys(self, def_id: DefId, tcx: TyCtxt<'tcx>) -> impl Iterator<Item = Ty<'tcx>> {
564 self.upvar_tys(def_id, tcx)
568 #[derive(Debug, Copy, Clone)]
569 pub enum UpvarSubsts<'tcx> {
570 Closure(ClosureSubsts<'tcx>),
571 Generator(GeneratorSubsts<'tcx>),
574 impl<'tcx> UpvarSubsts<'tcx> {
580 ) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
581 let upvar_kinds = match self {
582 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
583 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
585 upvar_kinds.iter().map(|t| {
586 if let UnpackedKind::Type(ty) = t.unpack() {
589 bug!("upvar should be type")
595 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash,
596 RustcEncodable, RustcDecodable, HashStable)]
597 pub enum ExistentialPredicate<'tcx> {
598 /// E.g., `Iterator`.
599 Trait(ExistentialTraitRef<'tcx>),
600 /// E.g., `Iterator::Item = T`.
601 Projection(ExistentialProjection<'tcx>),
606 impl<'tcx> ExistentialPredicate<'tcx> {
607 /// Compares via an ordering that will not change if modules are reordered or other changes are
608 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
609 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
610 use self::ExistentialPredicate::*;
611 match (*self, *other) {
612 (Trait(_), Trait(_)) => Ordering::Equal,
613 (Projection(ref a), Projection(ref b)) =>
614 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
615 (AutoTrait(ref a), AutoTrait(ref b)) =>
616 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
617 (Trait(_), _) => Ordering::Less,
618 (Projection(_), Trait(_)) => Ordering::Greater,
619 (Projection(_), _) => Ordering::Less,
620 (AutoTrait(_), _) => Ordering::Greater,
625 impl<'tcx> Binder<ExistentialPredicate<'tcx>> {
626 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
627 use crate::ty::ToPredicate;
628 match *self.skip_binder() {
629 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
630 ExistentialPredicate::Projection(p) =>
631 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
632 ExistentialPredicate::AutoTrait(did) => {
633 let trait_ref = Binder(ty::TraitRef {
635 substs: tcx.mk_substs_trait(self_ty, &[]),
637 trait_ref.to_predicate()
643 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
645 impl<'tcx> List<ExistentialPredicate<'tcx>> {
646 /// Returns the "principal def id" of this set of existential predicates.
648 /// A Rust trait object type consists (in addition to a lifetime bound)
649 /// of a set of trait bounds, which are separated into any number
650 /// of auto-trait bounds, and at most one non-auto-trait bound. The
651 /// non-auto-trait bound is called the "principal" of the trait
654 /// Only the principal can have methods or type parameters (because
655 /// auto traits can have neither of them). This is important, because
656 /// it means the auto traits can be treated as an unordered set (methods
657 /// would force an order for the vtable, while relating traits with
658 /// type parameters without knowing the order to relate them in is
659 /// a rather non-trivial task).
661 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
662 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
663 /// are the set `{Sync}`.
665 /// It is also possible to have a "trivial" trait object that
666 /// consists only of auto traits, with no principal - for example,
667 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
668 /// is `{Send, Sync}`, while there is no principal. These trait objects
669 /// have a "trivial" vtable consisting of just the size, alignment,
671 pub fn principal(&self) -> Option<ExistentialTraitRef<'tcx>> {
673 ExistentialPredicate::Trait(tr) => Some(tr),
678 pub fn principal_def_id(&self) -> Option<DefId> {
679 self.principal().map(|d| d.def_id)
683 pub fn projection_bounds<'a>(&'a self) ->
684 impl Iterator<Item = ExistentialProjection<'tcx>> + 'a
686 self.iter().filter_map(|predicate| {
688 ExistentialPredicate::Projection(p) => Some(p),
695 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
696 self.iter().filter_map(|predicate| {
698 ExistentialPredicate::AutoTrait(d) => Some(d),
705 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
706 pub fn principal(&self) -> Option<ty::Binder<ExistentialTraitRef<'tcx>>> {
707 self.skip_binder().principal().map(Binder::bind)
710 pub fn principal_def_id(&self) -> Option<DefId> {
711 self.skip_binder().principal_def_id()
715 pub fn projection_bounds<'a>(&'a self) ->
716 impl Iterator<Item = PolyExistentialProjection<'tcx>> + 'a {
717 self.skip_binder().projection_bounds().map(Binder::bind)
721 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
722 self.skip_binder().auto_traits()
725 pub fn iter<'a>(&'a self)
726 -> impl DoubleEndedIterator<Item = Binder<ExistentialPredicate<'tcx>>> + 'tcx {
727 self.skip_binder().iter().cloned().map(Binder::bind)
731 /// A complete reference to a trait. These take numerous guises in syntax,
732 /// but perhaps the most recognizable form is in a where-clause:
736 /// This would be represented by a trait-reference where the `DefId` is the
737 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
738 /// and `U` as parameter 1.
740 /// Trait references also appear in object types like `Foo<U>`, but in
741 /// that case the `Self` parameter is absent from the substitutions.
743 /// Note that a `TraitRef` introduces a level of region binding, to
744 /// account for higher-ranked trait bounds like `T: for<'a> Foo<&'a U>`
745 /// or higher-ranked object types.
746 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
747 pub struct TraitRef<'tcx> {
749 pub substs: SubstsRef<'tcx>,
752 impl<'tcx> TraitRef<'tcx> {
753 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
754 TraitRef { def_id: def_id, substs: substs }
757 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
758 /// are the parameters defined on trait.
759 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> TraitRef<'tcx> {
762 substs: InternalSubsts::identity_for_item(tcx, def_id),
767 pub fn self_ty(&self) -> Ty<'tcx> {
768 self.substs.type_at(0)
771 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
772 // Select only the "input types" from a trait-reference. For
773 // now this is all the types that appear in the
774 // trait-reference, but it should eventually exclude
782 substs: SubstsRef<'tcx>,
783 ) -> ty::TraitRef<'tcx> {
784 let defs = tcx.generics_of(trait_id);
788 substs: tcx.intern_substs(&substs[..defs.params.len()])
793 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
795 impl<'tcx> PolyTraitRef<'tcx> {
796 pub fn self_ty(&self) -> Ty<'tcx> {
797 self.skip_binder().self_ty()
800 pub fn def_id(&self) -> DefId {
801 self.skip_binder().def_id
804 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
805 // Note that we preserve binding levels
806 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
810 /// An existential reference to a trait, where `Self` is erased.
811 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
813 /// exists T. T: Trait<'a, 'b, X, Y>
815 /// The substitutions don't include the erased `Self`, only trait
816 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
817 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash,
818 RustcEncodable, RustcDecodable, HashStable)]
819 pub struct ExistentialTraitRef<'tcx> {
821 pub substs: SubstsRef<'tcx>,
824 impl<'tcx> ExistentialTraitRef<'tcx> {
825 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
826 // Select only the "input types" from a trait-reference. For
827 // now this is all the types that appear in the
828 // trait-reference, but it should eventually exclude
833 pub fn erase_self_ty(
835 trait_ref: ty::TraitRef<'tcx>,
836 ) -> ty::ExistentialTraitRef<'tcx> {
837 // Assert there is a Self.
838 trait_ref.substs.type_at(0);
840 ty::ExistentialTraitRef {
841 def_id: trait_ref.def_id,
842 substs: tcx.intern_substs(&trait_ref.substs[1..])
846 /// Object types don't have a self type specified. Therefore, when
847 /// we convert the principal trait-ref into a normal trait-ref,
848 /// you must give *some* self type. A common choice is `mk_err()`
849 /// or some placeholder type.
850 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
851 // otherwise the escaping vars would be captured by the binder
852 // debug_assert!(!self_ty.has_escaping_bound_vars());
856 substs: tcx.mk_substs_trait(self_ty, self.substs)
861 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
863 impl<'tcx> PolyExistentialTraitRef<'tcx> {
864 pub fn def_id(&self) -> DefId {
865 self.skip_binder().def_id
868 /// Object types don't have a self type specified. Therefore, when
869 /// we convert the principal trait-ref into a normal trait-ref,
870 /// you must give *some* self type. A common choice is `mk_err()`
871 /// or some placeholder type.
872 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
873 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
877 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
878 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
879 /// (which would be represented by the type `PolyTraitRef ==
880 /// Binder<TraitRef>`). Note that when we instantiate,
881 /// erase, or otherwise "discharge" these bound vars, we change the
882 /// type from `Binder<T>` to just `T` (see
883 /// e.g., `liberate_late_bound_regions`).
884 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
885 pub struct Binder<T>(T);
888 /// Wraps `value` in a binder, asserting that `value` does not
889 /// contain any bound vars that would be bound by the
890 /// binder. This is commonly used to 'inject' a value T into a
891 /// different binding level.
892 pub fn dummy<'tcx>(value: T) -> Binder<T>
893 where T: TypeFoldable<'tcx>
895 debug_assert!(!value.has_escaping_bound_vars());
899 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
900 pub fn bind(value: T) -> Binder<T> {
904 /// Skips the binder and returns the "bound" value. This is a
905 /// risky thing to do because it's easy to get confused about
906 /// De Bruijn indices and the like. It is usually better to
907 /// discharge the binder using `no_bound_vars` or
908 /// `replace_late_bound_regions` or something like
909 /// that. `skip_binder` is only valid when you are either
910 /// extracting data that has nothing to do with bound vars, you
911 /// are doing some sort of test that does not involve bound
912 /// regions, or you are being very careful about your depth
915 /// Some examples where `skip_binder` is reasonable:
917 /// - extracting the `DefId` from a PolyTraitRef;
918 /// - comparing the self type of a PolyTraitRef to see if it is equal to
919 /// a type parameter `X`, since the type `X` does not reference any regions
920 pub fn skip_binder(&self) -> &T {
924 pub fn as_ref(&self) -> Binder<&T> {
928 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
929 where F: FnOnce(&T) -> U
931 self.as_ref().map_bound(f)
934 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
935 where F: FnOnce(T) -> U
940 /// Unwraps and returns the value within, but only if it contains
941 /// no bound vars at all. (In other words, if this binder --
942 /// and indeed any enclosing binder -- doesn't bind anything at
943 /// all.) Otherwise, returns `None`.
945 /// (One could imagine having a method that just unwraps a single
946 /// binder, but permits late-bound vars bound by enclosing
947 /// binders, but that would require adjusting the debruijn
948 /// indices, and given the shallow binding structure we often use,
949 /// would not be that useful.)
950 pub fn no_bound_vars<'tcx>(self) -> Option<T>
951 where T: TypeFoldable<'tcx>
953 if self.skip_binder().has_escaping_bound_vars() {
956 Some(self.skip_binder().clone())
960 /// Given two things that have the same binder level,
961 /// and an operation that wraps on their contents, executes the operation
962 /// and then wraps its result.
964 /// `f` should consider bound regions at depth 1 to be free, and
965 /// anything it produces with bound regions at depth 1 will be
966 /// bound in the resulting return value.
967 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
968 where F: FnOnce(T, U) -> R
970 Binder(f(self.0, u.0))
973 /// Splits the contents into two things that share the same binder
974 /// level as the original, returning two distinct binders.
976 /// `f` should consider bound regions at depth 1 to be free, and
977 /// anything it produces with bound regions at depth 1 will be
978 /// bound in the resulting return values.
979 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
980 where F: FnOnce(T) -> (U, V)
982 let (u, v) = f(self.0);
983 (Binder(u), Binder(v))
987 /// Represents the projection of an associated type. In explicit UFCS
988 /// form this would be written `<T as Trait<..>>::N`.
989 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
990 Hash, Debug, RustcEncodable, RustcDecodable, HashStable)]
991 pub struct ProjectionTy<'tcx> {
992 /// The parameters of the associated item.
993 pub substs: SubstsRef<'tcx>,
995 /// The `DefId` of the `TraitItem` for the associated type `N`.
997 /// Note that this is not the `DefId` of the `TraitRef` containing this
998 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
999 pub item_def_id: DefId,
1002 impl<'tcx> ProjectionTy<'tcx> {
1003 /// Construct a `ProjectionTy` by searching the trait from `trait_ref` for the
1004 /// associated item named `item_name`.
1005 pub fn from_ref_and_name(
1007 trait_ref: ty::TraitRef<'tcx>,
1009 ) -> ProjectionTy<'tcx> {
1010 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
1011 item.kind == ty::AssocKind::Type &&
1012 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
1016 substs: trait_ref.substs,
1021 /// Extracts the underlying trait reference from this projection.
1022 /// For example, if this is a projection of `<T as Iterator>::Item`,
1023 /// then this function would return a `T: Iterator` trait reference.
1024 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::TraitRef<'tcx> {
1025 let def_id = tcx.associated_item(self.item_def_id).container.id();
1028 substs: self.substs,
1032 pub fn self_ty(&self) -> Ty<'tcx> {
1033 self.substs.type_at(0)
1037 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
1038 pub struct GenSig<'tcx> {
1039 pub yield_ty: Ty<'tcx>,
1040 pub return_ty: Ty<'tcx>,
1043 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
1045 impl<'tcx> PolyGenSig<'tcx> {
1046 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
1047 self.map_bound_ref(|sig| sig.yield_ty)
1049 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
1050 self.map_bound_ref(|sig| sig.return_ty)
1054 /// Signature of a function type, which I have arbitrarily
1055 /// decided to use to refer to the input/output types.
1057 /// - `inputs`: is the list of arguments and their modes.
1058 /// - `output`: is the return type.
1059 /// - `c_variadic`: indicates whether this is a C-variadic function.
1060 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord,
1061 Hash, RustcEncodable, RustcDecodable, HashStable)]
1062 pub struct FnSig<'tcx> {
1063 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1064 pub c_variadic: bool,
1065 pub unsafety: hir::Unsafety,
1069 impl<'tcx> FnSig<'tcx> {
1070 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1071 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1074 pub fn output(&self) -> Ty<'tcx> {
1075 self.inputs_and_output[self.inputs_and_output.len() - 1]
1078 // Create a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible method
1079 fn fake() -> FnSig<'tcx> {
1081 inputs_and_output: List::empty(),
1083 unsafety: hir::Unsafety::Normal,
1084 abi: abi::Abi::Rust,
1089 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
1091 impl<'tcx> PolyFnSig<'tcx> {
1093 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
1094 self.map_bound_ref(|fn_sig| fn_sig.inputs())
1097 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
1098 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1100 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
1101 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1104 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
1105 self.map_bound_ref(|fn_sig| fn_sig.output())
1107 pub fn c_variadic(&self) -> bool {
1108 self.skip_binder().c_variadic
1110 pub fn unsafety(&self) -> hir::Unsafety {
1111 self.skip_binder().unsafety
1113 pub fn abi(&self) -> abi::Abi {
1114 self.skip_binder().abi
1118 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
1121 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1122 Hash, RustcEncodable, RustcDecodable, HashStable)]
1123 pub struct ParamTy {
1125 pub name: InternedString,
1128 impl<'tcx> ParamTy {
1129 pub fn new(index: u32, name: InternedString) -> ParamTy {
1130 ParamTy { index, name: name }
1133 pub fn for_self() -> ParamTy {
1134 ParamTy::new(0, kw::SelfUpper.as_interned_str())
1137 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1138 ParamTy::new(def.index, def.name)
1141 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1142 tcx.mk_ty_param(self.index, self.name)
1146 #[derive(Copy, Clone, Hash, RustcEncodable, RustcDecodable,
1147 Eq, PartialEq, Ord, PartialOrd, HashStable)]
1148 pub struct ParamConst {
1150 pub name: InternedString,
1153 impl<'tcx> ParamConst {
1154 pub fn new(index: u32, name: InternedString) -> ParamConst {
1155 ParamConst { index, name }
1158 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1159 ParamConst::new(def.index, def.name)
1162 pub fn to_const(self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
1163 tcx.mk_const_param(self.index, self.name, ty)
1168 /// A [De Bruijn index][dbi] is a standard means of representing
1169 /// regions (and perhaps later types) in a higher-ranked setting. In
1170 /// particular, imagine a type like this:
1172 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1175 /// | +------------+ 0 | |
1177 /// +--------------------------------+ 1 |
1179 /// +------------------------------------------+ 0
1181 /// In this type, there are two binders (the outer fn and the inner
1182 /// fn). We need to be able to determine, for any given region, which
1183 /// fn type it is bound by, the inner or the outer one. There are
1184 /// various ways you can do this, but a De Bruijn index is one of the
1185 /// more convenient and has some nice properties. The basic idea is to
1186 /// count the number of binders, inside out. Some examples should help
1187 /// clarify what I mean.
1189 /// Let's start with the reference type `&'b isize` that is the first
1190 /// argument to the inner function. This region `'b` is assigned a De
1191 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1192 /// fn). The region `'a` that appears in the second argument type (`&'a
1193 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1194 /// second-innermost binder". (These indices are written on the arrays
1195 /// in the diagram).
1197 /// What is interesting is that De Bruijn index attached to a particular
1198 /// variable will vary depending on where it appears. For example,
1199 /// the final type `&'a char` also refers to the region `'a` declared on
1200 /// the outermost fn. But this time, this reference is not nested within
1201 /// any other binders (i.e., it is not an argument to the inner fn, but
1202 /// rather the outer one). Therefore, in this case, it is assigned a
1203 /// De Bruijn index of 0, because the innermost binder in that location
1204 /// is the outer fn.
1206 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1207 pub struct DebruijnIndex {
1208 DEBUG_FORMAT = "DebruijnIndex({})",
1209 const INNERMOST = 0,
1213 pub type Region<'tcx> = &'tcx RegionKind;
1215 /// Representation of regions.
1217 /// Unlike types, most region variants are "fictitious", not concrete,
1218 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1219 /// ones representing concrete regions.
1221 /// ## Bound Regions
1223 /// These are regions that are stored behind a binder and must be substituted
1224 /// with some concrete region before being used. There are two kind of
1225 /// bound regions: early-bound, which are bound in an item's `Generics`,
1226 /// and are substituted by a `InternalSubsts`, and late-bound, which are part of
1227 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1228 /// the likes of `liberate_late_bound_regions`. The distinction exists
1229 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1231 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1232 /// outside their binder, e.g., in types passed to type inference, and
1233 /// should first be substituted (by placeholder regions, free regions,
1234 /// or region variables).
1236 /// ## Placeholder and Free Regions
1238 /// One often wants to work with bound regions without knowing their precise
1239 /// identity. For example, when checking a function, the lifetime of a borrow
1240 /// can end up being assigned to some region parameter. In these cases,
1241 /// it must be ensured that bounds on the region can't be accidentally
1242 /// assumed without being checked.
1244 /// To do this, we replace the bound regions with placeholder markers,
1245 /// which don't satisfy any relation not explicitly provided.
1247 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1248 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1249 /// to be used. These also support explicit bounds: both the internally-stored
1250 /// *scope*, which the region is assumed to outlive, as well as other
1251 /// relations stored in the `FreeRegionMap`. Note that these relations
1252 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1253 /// `resolve_regions_and_report_errors`.
1255 /// When working with higher-ranked types, some region relations aren't
1256 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1257 /// `RePlaceholder` is designed for this purpose. In these contexts,
1258 /// there's also the risk that some inference variable laying around will
1259 /// get unified with your placeholder region: if you want to check whether
1260 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1261 /// with a placeholder region `'%a`, the variable `'_` would just be
1262 /// instantiated to the placeholder region `'%a`, which is wrong because
1263 /// the inference variable is supposed to satisfy the relation
1264 /// *for every value of the placeholder region*. To ensure that doesn't
1265 /// happen, you can use `leak_check`. This is more clearly explained
1266 /// by the [rustc guide].
1268 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1269 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1270 /// [rustc guide]: https://rust-lang.github.io/rustc-guide/traits/hrtb.html
1271 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1272 pub enum RegionKind {
1273 /// Region bound in a type or fn declaration which will be
1274 /// substituted 'early' -- that is, at the same time when type
1275 /// parameters are substituted.
1276 ReEarlyBound(EarlyBoundRegion),
1278 /// Region bound in a function scope, which will be substituted when the
1279 /// function is called.
1280 ReLateBound(DebruijnIndex, BoundRegion),
1282 /// When checking a function body, the types of all arguments and so forth
1283 /// that refer to bound region parameters are modified to refer to free
1284 /// region parameters.
1287 /// A concrete region naming some statically determined scope
1288 /// (e.g., an expression or sequence of statements) within the
1289 /// current function.
1290 ReScope(region::Scope),
1292 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1295 /// A region variable. Should not exist after typeck.
1298 /// A placeholder region - basically the higher-ranked version of ReFree.
1299 /// Should not exist after typeck.
1300 RePlaceholder(ty::PlaceholderRegion),
1302 /// Empty lifetime is for data that is never accessed.
1303 /// Bottom in the region lattice. We treat ReEmpty somewhat
1304 /// specially; at least right now, we do not generate instances of
1305 /// it during the GLB computations, but rather
1306 /// generate an error instead. This is to improve error messages.
1307 /// The only way to get an instance of ReEmpty is to have a region
1308 /// variable with no constraints.
1311 /// Erased region, used by trait selection, in MIR and during codegen.
1314 /// These are regions bound in the "defining type" for a
1315 /// closure. They are used ONLY as part of the
1316 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1317 /// See `ClosureRegionRequirements` for more details.
1318 ReClosureBound(RegionVid),
1321 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Region<'tcx> {}
1323 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1324 pub struct EarlyBoundRegion {
1327 pub name: InternedString,
1330 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1335 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1336 pub struct ConstVid<'tcx> {
1338 pub phantom: PhantomData<&'tcx ()>,
1341 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1346 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1347 pub struct FloatVid {
1352 pub struct RegionVid {
1353 DEBUG_FORMAT = custom,
1357 impl Atom for RegionVid {
1358 fn index(self) -> usize {
1363 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord,
1364 Hash, RustcEncodable, RustcDecodable, HashStable)]
1370 /// A `FreshTy` is one that is generated as a replacement for an
1371 /// unbound type variable. This is convenient for caching etc. See
1372 /// `infer::freshen` for more details.
1379 pub struct BoundVar { .. }
1382 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1383 pub struct BoundTy {
1385 pub kind: BoundTyKind,
1388 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1389 pub enum BoundTyKind {
1391 Param(InternedString),
1394 impl_stable_hash_for!(struct BoundTy { var, kind });
1395 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1397 impl From<BoundVar> for BoundTy {
1398 fn from(var: BoundVar) -> Self {
1401 kind: BoundTyKind::Anon,
1406 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1407 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash,
1408 Debug, RustcEncodable, RustcDecodable, HashStable)]
1409 pub struct ExistentialProjection<'tcx> {
1410 pub item_def_id: DefId,
1411 pub substs: SubstsRef<'tcx>,
1415 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1417 impl<'tcx> ExistentialProjection<'tcx> {
1418 /// Extracts the underlying existential trait reference from this projection.
1419 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1420 /// then this function would return a `exists T. T: Iterator` existential trait
1422 pub fn trait_ref(&self, tcx: TyCtxt<'_>) -> ty::ExistentialTraitRef<'tcx> {
1423 let def_id = tcx.associated_item(self.item_def_id).container.id();
1424 ty::ExistentialTraitRef{
1426 substs: self.substs,
1430 pub fn with_self_ty(
1434 ) -> ty::ProjectionPredicate<'tcx> {
1435 // otherwise the escaping regions would be captured by the binders
1436 debug_assert!(!self_ty.has_escaping_bound_vars());
1438 ty::ProjectionPredicate {
1439 projection_ty: ty::ProjectionTy {
1440 item_def_id: self.item_def_id,
1441 substs: tcx.mk_substs_trait(self_ty, self.substs),
1448 impl<'tcx> PolyExistentialProjection<'tcx> {
1449 pub fn with_self_ty(
1453 ) -> ty::PolyProjectionPredicate<'tcx> {
1454 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1457 pub fn item_def_id(&self) -> DefId {
1458 return self.skip_binder().item_def_id;
1462 impl DebruijnIndex {
1463 /// Returns the resulting index when this value is moved into
1464 /// `amount` number of new binders. So, e.g., if you had
1466 /// for<'a> fn(&'a x)
1468 /// and you wanted to change it to
1470 /// for<'a> fn(for<'b> fn(&'a x))
1472 /// you would need to shift the index for `'a` into a new binder.
1474 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1475 DebruijnIndex::from_u32(self.as_u32() + amount)
1478 /// Update this index in place by shifting it "in" through
1479 /// `amount` number of binders.
1480 pub fn shift_in(&mut self, amount: u32) {
1481 *self = self.shifted_in(amount);
1484 /// Returns the resulting index when this value is moved out from
1485 /// `amount` number of new binders.
1487 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1488 DebruijnIndex::from_u32(self.as_u32() - amount)
1491 /// Update in place by shifting out from `amount` binders.
1492 pub fn shift_out(&mut self, amount: u32) {
1493 *self = self.shifted_out(amount);
1496 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1497 /// innermost binder. That is, if we have something bound at `to_binder`,
1498 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1499 /// when moving a region out from inside binders:
1502 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1503 /// // Binder: D3 D2 D1 ^^
1506 /// Here, the region `'a` would have the De Bruijn index D3,
1507 /// because it is the bound 3 binders out. However, if we wanted
1508 /// to refer to that region `'a` in the second argument (the `_`),
1509 /// those two binders would not be in scope. In that case, we
1510 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1511 /// De Bruijn index of `'a` to D1 (the innermost binder).
1513 /// If we invoke `shift_out_to_binder` and the region is in fact
1514 /// bound by one of the binders we are shifting out of, that is an
1515 /// error (and should fail an assertion failure).
1516 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1517 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1521 impl_stable_hash_for!(struct DebruijnIndex { private });
1523 /// Region utilities
1525 /// Is this region named by the user?
1526 pub fn has_name(&self) -> bool {
1528 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1529 RegionKind::ReLateBound(_, br) => br.is_named(),
1530 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1531 RegionKind::ReScope(..) => false,
1532 RegionKind::ReStatic => true,
1533 RegionKind::ReVar(..) => false,
1534 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1535 RegionKind::ReEmpty => false,
1536 RegionKind::ReErased => false,
1537 RegionKind::ReClosureBound(..) => false,
1541 pub fn is_late_bound(&self) -> bool {
1543 ty::ReLateBound(..) => true,
1548 pub fn is_placeholder(&self) -> bool {
1550 ty::RePlaceholder(..) => true,
1555 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1557 ty::ReLateBound(debruijn, _) => debruijn >= index,
1562 /// Adjusts any De Bruijn indices so as to make `to_binder` the
1563 /// innermost binder. That is, if we have something bound at `to_binder`,
1564 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1565 /// when moving a region out from inside binders:
1568 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1569 /// // Binder: D3 D2 D1 ^^
1572 /// Here, the region `'a` would have the De Bruijn index D3,
1573 /// because it is the bound 3 binders out. However, if we wanted
1574 /// to refer to that region `'a` in the second argument (the `_`),
1575 /// those two binders would not be in scope. In that case, we
1576 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1577 /// De Bruijn index of `'a` to D1 (the innermost binder).
1579 /// If we invoke `shift_out_to_binder` and the region is in fact
1580 /// bound by one of the binders we are shifting out of, that is an
1581 /// error (and should fail an assertion failure).
1582 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1584 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1585 debruijn.shifted_out_to_binder(to_binder),
1592 pub fn keep_in_local_tcx(&self) -> bool {
1593 if let ty::ReVar(..) = self {
1600 pub fn type_flags(&self) -> TypeFlags {
1601 let mut flags = TypeFlags::empty();
1603 if self.keep_in_local_tcx() {
1604 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1609 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1610 flags = flags | TypeFlags::HAS_RE_INFER;
1612 ty::RePlaceholder(..) => {
1613 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1614 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1616 ty::ReLateBound(..) => {
1617 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1619 ty::ReEarlyBound(..) => {
1620 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1621 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1626 ty::ReScope { .. } => {
1627 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1631 ty::ReClosureBound(..) => {
1632 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1637 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1638 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1641 debug!("type_flags({:?}) = {:?}", self, flags);
1646 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1647 /// For example, consider the regions in this snippet of code:
1651 /// ^^ -- early bound, declared on an impl
1653 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1654 /// ^^ ^^ ^ anonymous, late-bound
1655 /// | early-bound, appears in where-clauses
1656 /// late-bound, appears only in fn args
1661 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1662 /// of the impl, and for all the other highlighted regions, it
1663 /// would return the `DefId` of the function. In other cases (not shown), this
1664 /// function might return the `DefId` of a closure.
1665 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId {
1667 ty::ReEarlyBound(br) => {
1668 tcx.parent(br.def_id).unwrap()
1670 ty::ReFree(fr) => fr.scope,
1671 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1677 impl<'tcx> TyS<'tcx> {
1679 pub fn is_unit(&self) -> bool {
1681 Tuple(ref tys) => tys.is_empty(),
1687 pub fn is_never(&self) -> bool {
1694 /// Checks whether a type is definitely uninhabited. This is
1695 /// conservative: for some types that are uninhabited we return `false`,
1696 /// but we only return `true` for types that are definitely uninhabited.
1697 /// `ty.conservative_is_privately_uninhabited` implies that any value of type `ty`
1698 /// will be `Abi::Uninhabited`. (Note that uninhabited types may have nonzero
1699 /// size, to account for partial initialisation. See #49298 for details.)
1700 pub fn conservative_is_privately_uninhabited(&self, tcx: TyCtxt<'tcx>) -> bool {
1701 // FIXME(varkor): we can make this less conversative by substituting concrete
1705 ty::Adt(def, _) if def.is_union() => {
1706 // For now, `union`s are never considered uninhabited.
1709 ty::Adt(def, _) => {
1710 // Any ADT is uninhabited if either:
1711 // (a) It has no variants (i.e. an empty `enum`);
1712 // (b) Each of its variants (a single one in the case of a `struct`) has at least
1713 // one uninhabited field.
1714 def.variants.iter().all(|var| {
1715 var.fields.iter().any(|field| {
1716 tcx.type_of(field.did).conservative_is_privately_uninhabited(tcx)
1720 ty::Tuple(..) => self.tuple_fields().any(|ty| {
1721 ty.conservative_is_privately_uninhabited(tcx)
1723 ty::Array(ty, len) => {
1724 match len.try_eval_usize(tcx, ParamEnv::empty()) {
1725 // If the array is definitely non-empty, it's uninhabited if
1726 // the type of its elements is uninhabited.
1727 Some(n) if n != 0 => ty.conservative_is_privately_uninhabited(tcx),
1732 // References to uninitialised memory is valid for any type, including
1733 // uninhabited types, in unsafe code, so we treat all references as
1742 pub fn is_primitive(&self) -> bool {
1744 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1750 pub fn is_ty_var(&self) -> bool {
1752 Infer(TyVar(_)) => true,
1758 pub fn is_ty_infer(&self) -> bool {
1766 pub fn is_phantom_data(&self) -> bool {
1767 if let Adt(def, _) = self.sty {
1768 def.is_phantom_data()
1775 pub fn is_bool(&self) -> bool { self.sty == Bool }
1778 pub fn is_param(&self, index: u32) -> bool {
1780 ty::Param(ref data) => data.index == index,
1786 pub fn is_slice(&self) -> bool {
1788 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1789 Slice(_) | Str => true,
1797 pub fn is_simd(&self) -> bool {
1799 Adt(def, _) => def.repr.simd(),
1804 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1806 Array(ty, _) | Slice(ty) => ty,
1807 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1808 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1812 pub fn simd_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1814 Adt(def, substs) => {
1815 def.non_enum_variant().fields[0].ty(tcx, substs)
1817 _ => bug!("simd_type called on invalid type")
1821 pub fn simd_size(&self, _cx: TyCtxt<'_>) -> usize {
1823 Adt(def, _) => def.non_enum_variant().fields.len(),
1824 _ => bug!("simd_size called on invalid type")
1829 pub fn is_region_ptr(&self) -> bool {
1837 pub fn is_mutable_ptr(&self) -> bool {
1839 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1840 Ref(_, _, hir::Mutability::MutMutable) => true,
1846 pub fn is_unsafe_ptr(&self) -> bool {
1848 RawPtr(_) => return true,
1853 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1855 pub fn is_any_ptr(&self) -> bool {
1856 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1859 /// Returns `true` if this type is an `Arc<T>`.
1861 pub fn is_arc(&self) -> bool {
1863 Adt(def, _) => def.is_arc(),
1868 /// Returns `true` if this type is an `Rc<T>`.
1870 pub fn is_rc(&self) -> bool {
1872 Adt(def, _) => def.is_rc(),
1878 pub fn is_box(&self) -> bool {
1880 Adt(def, _) => def.is_box(),
1885 /// panics if called on any type other than `Box<T>`
1886 pub fn boxed_ty(&self) -> Ty<'tcx> {
1888 Adt(def, substs) if def.is_box() => substs.type_at(0),
1889 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1893 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1894 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1895 /// contents are abstract to rustc.)
1897 pub fn is_scalar(&self) -> bool {
1899 Bool | Char | Int(_) | Float(_) | Uint(_) |
1900 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1901 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1906 /// Returns `true` if this type is a floating point type.
1908 pub fn is_floating_point(&self) -> bool {
1911 Infer(FloatVar(_)) => true,
1917 pub fn is_trait(&self) -> bool {
1919 Dynamic(..) => true,
1925 pub fn is_enum(&self) -> bool {
1927 Adt(adt_def, _) => {
1935 pub fn is_closure(&self) -> bool {
1937 Closure(..) => true,
1943 pub fn is_generator(&self) -> bool {
1945 Generator(..) => true,
1951 pub fn is_integral(&self) -> bool {
1953 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1959 pub fn is_fresh_ty(&self) -> bool {
1961 Infer(FreshTy(_)) => true,
1967 pub fn is_fresh(&self) -> bool {
1969 Infer(FreshTy(_)) => true,
1970 Infer(FreshIntTy(_)) => true,
1971 Infer(FreshFloatTy(_)) => true,
1977 pub fn is_char(&self) -> bool {
1985 pub fn is_numeric(&self) -> bool {
1986 self.is_integral() || self.is_floating_point()
1990 pub fn is_signed(&self) -> bool {
1998 pub fn is_ptr_sized_integral(&self) -> bool {
2000 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => true,
2006 pub fn is_machine(&self) -> bool {
2008 Int(..) | Uint(..) | Float(..) => true,
2014 pub fn has_concrete_skeleton(&self) -> bool {
2016 Param(_) | Infer(_) | Error => false,
2021 /// Returns the type and mutability of `*ty`.
2023 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2024 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2025 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2027 Adt(def, _) if def.is_box() => {
2029 ty: self.boxed_ty(),
2030 mutbl: hir::MutImmutable,
2033 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
2034 RawPtr(mt) if explicit => Some(mt),
2039 /// Returns the type of `ty[i]`.
2040 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2042 Array(ty, _) | Slice(ty) => Some(ty),
2047 pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2049 FnDef(def_id, substs) => {
2050 tcx.fn_sig(def_id).subst(tcx, substs)
2053 Error => { // ignore errors (#54954)
2054 ty::Binder::dummy(FnSig::fake())
2056 Closure(..) => bug!(
2057 "to get the signature of a closure, use `closure_sig()` not `fn_sig()`",
2059 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
2064 pub fn is_fn(&self) -> bool {
2066 FnDef(..) | FnPtr(_) => true,
2072 pub fn is_fn_ptr(&self) -> bool {
2080 pub fn is_impl_trait(&self) -> bool {
2088 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
2090 Adt(adt, _) => Some(adt),
2095 /// Iterates over tuple fields.
2096 /// Panics when called on anything but a tuple.
2097 pub fn tuple_fields(&self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> {
2099 Tuple(substs) => substs.iter().map(|field| field.expect_ty()),
2100 _ => bug!("tuple_fields called on non-tuple"),
2104 /// If the type contains variants, returns the valid range of variant indices.
2105 /// FIXME This requires the optimized MIR in the case of generators.
2107 pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2109 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2110 TyKind::Generator(def_id, substs, _) => Some(substs.variant_range(def_id, tcx)),
2115 /// If the type contains variants, returns the variant for `variant_index`.
2116 /// Panics if `variant_index` is out of range.
2117 /// FIXME This requires the optimized MIR in the case of generators.
2119 pub fn discriminant_for_variant(
2122 variant_index: VariantIdx,
2123 ) -> Option<Discr<'tcx>> {
2125 TyKind::Adt(adt, _) => Some(adt.discriminant_for_variant(tcx, variant_index)),
2126 TyKind::Generator(def_id, substs, _) =>
2127 Some(substs.discriminant_for_variant(def_id, tcx, variant_index)),
2132 /// Push onto `out` the regions directly referenced from this type (but not
2133 /// types reachable from this type via `walk_tys`). This ignores late-bound
2134 /// regions binders.
2135 pub fn push_regions(&self, out: &mut SmallVec<[ty::Region<'tcx>; 4]>) {
2137 Ref(region, _, _) => {
2140 Dynamic(ref obj, region) => {
2142 if let Some(principal) = obj.principal() {
2143 out.extend(principal.skip_binder().substs.regions());
2146 Adt(_, substs) | Opaque(_, substs) => {
2147 out.extend(substs.regions())
2149 Closure(_, ClosureSubsts { ref substs }) |
2150 Generator(_, GeneratorSubsts { ref substs }, _) => {
2151 out.extend(substs.regions())
2153 Projection(ref data) | UnnormalizedProjection(ref data) => {
2154 out.extend(data.substs.regions())
2158 GeneratorWitness(..) |
2179 /// When we create a closure, we record its kind (i.e., what trait
2180 /// it implements) into its `ClosureSubsts` using a type
2181 /// parameter. This is kind of a phantom type, except that the
2182 /// most convenient thing for us to are the integral types. This
2183 /// function converts such a special type into the closure
2184 /// kind. To go the other way, use
2185 /// `tcx.closure_kind_ty(closure_kind)`.
2187 /// Note that during type checking, we use an inference variable
2188 /// to represent the closure kind, because it has not yet been
2189 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
2190 /// is complete, that type variable will be unified.
2191 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2193 Int(int_ty) => match int_ty {
2194 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
2195 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2196 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2197 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2202 Error => Some(ty::ClosureKind::Fn),
2204 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2208 /// Fast path helper for testing if a type is `Sized`.
2210 /// Returning true means the type is known to be sized. Returning
2211 /// `false` means nothing -- could be sized, might not be.
2212 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool {
2214 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
2215 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
2216 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
2217 ty::Char | ty::Ref(..) | ty::Generator(..) |
2218 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
2219 ty::Never | ty::Error =>
2222 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
2226 tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx))
2229 ty::Adt(def, _substs) =>
2230 def.sized_constraint(tcx).is_empty(),
2232 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2234 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
2236 ty::Infer(ty::TyVar(_)) => false,
2239 ty::Placeholder(..) |
2240 ty::Infer(ty::FreshTy(_)) |
2241 ty::Infer(ty::FreshIntTy(_)) |
2242 ty::Infer(ty::FreshFloatTy(_)) =>
2243 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
2248 /// Typed constant value.
2249 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable,
2250 Eq, PartialEq, Ord, PartialOrd, HashStable)]
2251 pub struct Const<'tcx> {
2254 pub val: ConstValue<'tcx>,
2257 #[cfg(target_arch = "x86_64")]
2258 static_assert_size!(Const<'_>, 40);
2260 impl<'tcx> Const<'tcx> {
2262 pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
2264 val: ConstValue::Scalar(val),
2270 pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> &'tcx Self {
2271 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2272 panic!("could not compute layout for {:?}: {:?}", ty, e)
2274 Self::from_scalar(tcx, Scalar::from_uint(bits, size), ty.value)
2278 pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2279 Self::from_scalar(tcx, Scalar::zst(), ty)
2283 pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> &'tcx Self {
2284 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2288 pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> &'tcx Self {
2289 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2293 pub fn try_eval_bits(
2296 param_env: ParamEnv<'tcx>,
2299 assert_eq!(self.ty, ty);
2300 // if `ty` does not depend on generic parameters, use an empty param_env
2301 let size = tcx.layout_of(param_env.with_reveal_all().and(ty)).ok()?.size;
2302 self.eval(tcx, param_env).val.try_to_bits(size)
2309 param_env: ParamEnv<'tcx>,
2311 // FIXME(const_generics): this doesn't work right now,
2312 // because it tries to relate an `Infer` to a `Param`.
2314 ConstValue::Unevaluated(did, substs) => {
2315 // if `substs` has no unresolved components, use and empty param_env
2316 let (param_env, substs) = param_env.with_reveal_all().and(substs).into_parts();
2317 // try to resolve e.g. associated constants to their definition on an impl
2318 let instance = match ty::Instance::resolve(tcx, param_env, did, substs) {
2319 Some(instance) => instance,
2320 None => return self,
2322 let gid = GlobalId {
2326 tcx.const_eval(param_env.and(gid)).unwrap_or(self)
2333 pub fn try_eval_bool(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
2334 self.try_eval_bits(tcx, param_env, tcx.types.bool).and_then(|v| match v {
2342 pub fn try_eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> {
2343 self.try_eval_bits(tcx, param_env, tcx.types.usize).map(|v| v as u64)
2347 pub fn eval_bits(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
2348 self.try_eval_bits(tcx, param_env, ty).unwrap_or_else(||
2349 bug!("expected bits of {:#?}, got {:#?}", ty, self))
2353 pub fn eval_usize(&self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 {
2354 self.eval_bits(tcx, param_env, tcx.types.usize) as u64
2358 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
2360 /// An inference variable for a const, for use in const generics.
2361 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd,
2362 Ord, RustcEncodable, RustcDecodable, Hash, HashStable)]
2363 pub enum InferConst<'tcx> {
2364 /// Infer the value of the const.
2365 Var(ConstVid<'tcx>),
2366 /// A fresh const variable. See `infer::freshen` for more details.
2368 /// Canonicalized const variable, used only when preparing a trait query.
2369 Canonical(DebruijnIndex, BoundVar),