1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! This module contains TyKind and its major components
13 use hir::def_id::DefId;
14 use infer::canonical::Canonical;
15 use mir::interpret::ConstValue;
17 use polonius_engine::Atom;
18 use rustc_data_structures::indexed_vec::Idx;
19 use ty::subst::{Substs, Subst, Kind, UnpackedKind};
20 use ty::{self, AdtDef, TypeFlags, Ty, TyCtxt, TypeFoldable};
21 use ty::{List, TyS, ParamEnvAnd, ParamEnv};
22 use util::captures::Captures;
23 use mir::interpret::{Scalar, Pointer};
26 use std::cmp::Ordering;
27 use rustc_target::spec::abi;
28 use syntax::ast::{self, Ident};
29 use syntax::symbol::{keywords, InternedString};
38 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
39 pub struct TypeAndMut<'tcx> {
41 pub mutbl: hir::Mutability,
44 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
45 RustcEncodable, RustcDecodable, Copy)]
46 /// A "free" region `fr` can be interpreted as "some region
47 /// at least as big as the scope `fr.scope`".
48 pub struct FreeRegion {
50 pub bound_region: BoundRegion,
53 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash,
54 RustcEncodable, RustcDecodable, Copy)]
55 pub enum BoundRegion {
56 /// An anonymous region parameter for a given fn (&T)
59 /// Named region parameters for functions (a in &'a T)
61 /// The def-id is needed to distinguish free regions in
62 /// the event of shadowing.
63 BrNamed(DefId, InternedString),
65 /// Fresh bound identifiers created during GLB computations.
68 /// Anonymous region for the implicit env pointer parameter
74 pub fn is_named(&self) -> bool {
76 BoundRegion::BrNamed(..) => true,
81 /// When canonicalizing, we replace unbound inference variables and free
82 /// regions with anonymous late bound regions. This method asserts that
83 /// we have an anonymous late bound region, which hence may refer to
84 /// a canonical variable.
85 pub fn as_bound_var(&self) -> BoundVar {
87 BoundRegion::BrAnon(var) => BoundVar::from_u32(var),
88 _ => bug!("bound region is not anonymous"),
93 /// N.B., If you change this, you'll probably want to change the corresponding
94 /// AST structure in `libsyntax/ast.rs` as well.
95 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
96 pub enum TyKind<'tcx> {
97 /// The primitive boolean type. Written as `bool`.
100 /// The primitive character type; holds a Unicode scalar value
101 /// (a non-surrogate code point). Written as `char`.
104 /// A primitive signed integer type. For example, `i32`.
107 /// A primitive unsigned integer type. For example, `u32`.
110 /// A primitive floating-point type. For example, `f64`.
113 /// Structures, enumerations and unions.
115 /// Substs here, possibly against intuition, *may* contain `Param`s.
116 /// That is, even after substitution it is possible that there are type
117 /// variables. This happens when the `Adt` corresponds to an ADT
118 /// definition and not a concrete use of it.
119 Adt(&'tcx AdtDef, &'tcx Substs<'tcx>),
123 /// The pointee of a string slice. Written as `str`.
126 /// An array with the given length. Written as `[T; n]`.
127 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
129 /// The pointee of an array slice. Written as `[T]`.
132 /// A raw pointer. Written as `*mut T` or `*const T`
133 RawPtr(TypeAndMut<'tcx>),
135 /// A reference; a pointer with an associated lifetime. Written as
136 /// `&'a mut T` or `&'a T`.
137 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
139 /// The anonymous type of a function declaration/definition. Each
140 /// function has a unique type, which is output (for a function
141 /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
143 /// For example the type of `bar` here:
146 /// fn foo() -> i32 { 1 }
147 /// let bar = foo; // bar: fn() -> i32 {foo}
149 FnDef(DefId, &'tcx Substs<'tcx>),
151 /// A pointer to a function. Written as `fn() -> i32`.
153 /// For example the type of `bar` here:
156 /// fn foo() -> i32 { 1 }
157 /// let bar: fn() -> i32 = foo;
159 FnPtr(PolyFnSig<'tcx>),
161 /// A trait, defined with `trait`.
162 Dynamic(Binder<&'tcx List<ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
164 /// The anonymous type of a closure. Used to represent the type of
166 Closure(DefId, ClosureSubsts<'tcx>),
168 /// The anonymous type of a generator. Used to represent the type of
170 Generator(DefId, GeneratorSubsts<'tcx>, hir::GeneratorMovability),
172 /// A type representin the types stored inside a generator.
173 /// This should only appear in GeneratorInteriors.
174 GeneratorWitness(Binder<&'tcx List<Ty<'tcx>>>),
176 /// The never type `!`
179 /// A tuple type. For example, `(i32, bool)`.
180 Tuple(&'tcx List<Ty<'tcx>>),
182 /// The projection of an associated type. For example,
183 /// `<T as Trait<..>>::N`.
184 Projection(ProjectionTy<'tcx>),
186 /// A placeholder type used when we do not have enough information
187 /// to normalize the projection of an associated type to an
188 /// existing concrete type. Currently only used with chalk-engine.
189 UnnormalizedProjection(ProjectionTy<'tcx>),
191 /// Opaque (`impl Trait`) type found in a return type.
192 /// The `DefId` comes either from
193 /// * the `impl Trait` ast::Ty node,
194 /// * or the `existential type` declaration
195 /// The substitutions are for the generics of the function in question.
196 /// After typeck, the concrete type can be found in the `types` map.
197 Opaque(DefId, &'tcx Substs<'tcx>),
199 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
202 /// Bound type variable, used only when preparing a trait query.
205 /// A type variable used during type checking.
208 /// A placeholder for a type which could not be computed; this is
209 /// propagated to avoid useless error messages.
213 /// A closure can be modeled as a struct that looks like:
215 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U0...Uk> {
223 /// - 'l0...'li and T0...Tj are the lifetime and type parameters
224 /// in scope on the function that defined the closure,
225 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
226 /// is rather hackily encoded via a scalar type. See
227 /// `TyS::to_opt_closure_kind` for details.
228 /// - CS represents the *closure signature*, representing as a `fn()`
229 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
230 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
232 /// - U0...Uk are type parameters representing the types of its upvars
233 /// (borrowed, if appropriate; that is, if Ui represents a by-ref upvar,
234 /// and the up-var has the type `Foo`, then `Ui = &Foo`).
236 /// So, for example, given this function:
238 /// fn foo<'a, T>(data: &'a mut T) {
239 /// do(|| data.count += 1)
242 /// the type of the closure would be something like:
244 /// struct Closure<'a, T, U0> {
248 /// Note that the type of the upvar is not specified in the struct.
249 /// You may wonder how the impl would then be able to use the upvar,
250 /// if it doesn't know it's type? The answer is that the impl is
251 /// (conceptually) not fully generic over Closure but rather tied to
252 /// instances with the expected upvar types:
254 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, &'b mut &'a mut T> {
258 /// You can see that the *impl* fully specified the type of the upvar
259 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
260 /// (Here, I am assuming that `data` is mut-borrowed.)
262 /// Now, the last question you may ask is: Why include the upvar types
263 /// as extra type parameters? The reason for this design is that the
264 /// upvar types can reference lifetimes that are internal to the
265 /// creating function. In my example above, for example, the lifetime
266 /// `'b` represents the scope of the closure itself; this is some
267 /// subset of `foo`, probably just the scope of the call to the to
268 /// `do()`. If we just had the lifetime/type parameters from the
269 /// enclosing function, we couldn't name this lifetime `'b`. Note that
270 /// there can also be lifetimes in the types of the upvars themselves,
271 /// if one of them happens to be a reference to something that the
272 /// creating fn owns.
274 /// OK, you say, so why not create a more minimal set of parameters
275 /// that just includes the extra lifetime parameters? The answer is
276 /// primarily that it would be hard --- we don't know at the time when
277 /// we create the closure type what the full types of the upvars are,
278 /// nor do we know which are borrowed and which are not. In this
279 /// design, we can just supply a fresh type parameter and figure that
282 /// All right, you say, but why include the type parameters from the
283 /// original function then? The answer is that codegen may need them
284 /// when monomorphizing, and they may not appear in the upvars. A
285 /// closure could capture no variables but still make use of some
286 /// in-scope type parameter with a bound (e.g., if our example above
287 /// had an extra `U: Default`, and the closure called `U::default()`).
289 /// There is another reason. This design (implicitly) prohibits
290 /// closures from capturing themselves (except via a trait
291 /// object). This simplifies closure inference considerably, since it
292 /// means that when we infer the kind of a closure or its upvars, we
293 /// don't have to handle cycles where the decisions we make for
294 /// closure C wind up influencing the decisions we ought to make for
295 /// closure C (which would then require fixed point iteration to
296 /// handle). Plus it fixes an ICE. :P
300 /// Perhaps surprisingly, `ClosureSubsts` are also used for
301 /// generators. In that case, what is written above is only half-true
302 /// -- the set of type parameters is similar, but the role of CK and
303 /// CS are different. CK represents the "yield type" and CS
304 /// represents the "return type" of the generator.
306 /// It'd be nice to split this struct into ClosureSubsts and
307 /// GeneratorSubsts, I believe. -nmatsakis
308 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
309 pub struct ClosureSubsts<'tcx> {
310 /// Lifetime and type parameters from the enclosing function,
311 /// concatenated with the types of the upvars.
313 /// These are separated out because codegen wants to pass them around
314 /// when monomorphizing.
315 pub substs: &'tcx Substs<'tcx>,
318 /// Struct returned by `split()`. Note that these are subslices of the
319 /// parent slice and not canonical substs themselves.
320 struct SplitClosureSubsts<'tcx> {
321 closure_kind_ty: Ty<'tcx>,
322 closure_sig_ty: Ty<'tcx>,
323 upvar_kinds: &'tcx [Kind<'tcx>],
326 impl<'tcx> ClosureSubsts<'tcx> {
327 /// Divides the closure substs into their respective
328 /// components. Single source of truth with respect to the
330 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitClosureSubsts<'tcx> {
331 let generics = tcx.generics_of(def_id);
332 let parent_len = generics.parent_count;
334 closure_kind_ty: self.substs.type_at(parent_len),
335 closure_sig_ty: self.substs.type_at(parent_len + 1),
336 upvar_kinds: &self.substs[parent_len + 2..],
341 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
342 impl Iterator<Item=Ty<'tcx>> + 'tcx
344 let SplitClosureSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
345 upvar_kinds.iter().map(|t| {
346 if let UnpackedKind::Type(ty) = t.unpack() {
349 bug!("upvar should be type")
354 /// Returns the closure kind for this closure; may return a type
355 /// variable during inference. To get the closure kind during
356 /// inference, use `infcx.closure_kind(def_id, substs)`.
357 pub fn closure_kind_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
358 self.split(def_id, tcx).closure_kind_ty
361 /// Returns the type representing the closure signature for this
362 /// closure; may contain type variables during inference. To get
363 /// the closure signature during inference, use
364 /// `infcx.fn_sig(def_id)`.
365 pub fn closure_sig_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
366 self.split(def_id, tcx).closure_sig_ty
369 /// Returns the closure kind for this closure; only usable outside
370 /// of an inference context, because in that context we know that
371 /// there are no type variables.
373 /// If you have an inference context, use `infcx.closure_kind()`.
374 pub fn closure_kind(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::ClosureKind {
375 self.split(def_id, tcx).closure_kind_ty.to_opt_closure_kind().unwrap()
378 /// Extracts the signature from the closure; only usable outside
379 /// of an inference context, because in that context we know that
380 /// there are no type variables.
382 /// If you have an inference context, use `infcx.closure_sig()`.
383 pub fn closure_sig(self, def_id: DefId, tcx: TyCtxt<'_, 'tcx, 'tcx>) -> ty::PolyFnSig<'tcx> {
384 match self.closure_sig_ty(def_id, tcx).sty {
385 ty::FnPtr(sig) => sig,
386 ref t => bug!("closure_sig_ty is not a fn-ptr: {:?}", t),
391 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
392 pub struct GeneratorSubsts<'tcx> {
393 pub substs: &'tcx Substs<'tcx>,
396 struct SplitGeneratorSubsts<'tcx> {
400 upvar_kinds: &'tcx [Kind<'tcx>],
403 impl<'tcx> GeneratorSubsts<'tcx> {
404 fn split(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> SplitGeneratorSubsts<'tcx> {
405 let generics = tcx.generics_of(def_id);
406 let parent_len = generics.parent_count;
407 SplitGeneratorSubsts {
408 yield_ty: self.substs.type_at(parent_len),
409 return_ty: self.substs.type_at(parent_len + 1),
410 witness: self.substs.type_at(parent_len + 2),
411 upvar_kinds: &self.substs[parent_len + 3..],
415 /// This describes the types that can be contained in a generator.
416 /// It will be a type variable initially and unified in the last stages of typeck of a body.
417 /// It contains a tuple of all the types that could end up on a generator frame.
418 /// The state transformation MIR pass may only produce layouts which mention types
419 /// in this tuple. Upvars are not counted here.
420 pub fn witness(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
421 self.split(def_id, tcx).witness
425 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
426 impl Iterator<Item=Ty<'tcx>> + 'tcx
428 let SplitGeneratorSubsts { upvar_kinds, .. } = self.split(def_id, tcx);
429 upvar_kinds.iter().map(|t| {
430 if let UnpackedKind::Type(ty) = t.unpack() {
433 bug!("upvar should be type")
438 /// Returns the type representing the yield type of the generator.
439 pub fn yield_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
440 self.split(def_id, tcx).yield_ty
443 /// Returns the type representing the return type of the generator.
444 pub fn return_ty(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> Ty<'tcx> {
445 self.split(def_id, tcx).return_ty
448 /// Return the "generator signature", which consists of its yield
449 /// and return types.
451 /// NB. Some bits of the code prefers to see this wrapped in a
452 /// binder, but it never contains bound regions. Probably this
453 /// function should be removed.
454 pub fn poly_sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> PolyGenSig<'tcx> {
455 ty::Binder::dummy(self.sig(def_id, tcx))
458 /// Return the "generator signature", which consists of its yield
459 /// and return types.
460 pub fn sig(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) -> GenSig<'tcx> {
462 yield_ty: self.yield_ty(def_id, tcx),
463 return_ty: self.return_ty(def_id, tcx),
468 impl<'a, 'gcx, 'tcx> GeneratorSubsts<'tcx> {
469 /// This returns the types of the MIR locals which had to be stored across suspension points.
470 /// It is calculated in rustc_mir::transform::generator::StateTransform.
471 /// All the types here must be in the tuple in GeneratorInterior.
475 tcx: TyCtxt<'a, 'gcx, 'tcx>,
476 ) -> impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a {
477 let state = tcx.generator_layout(def_id).fields.iter();
478 state.map(move |d| d.ty.subst(tcx, self.substs))
481 /// This is the types of the fields of a generate which
482 /// is available before the generator transformation.
483 /// It includes the upvars and the state discriminant which is u32.
484 pub fn pre_transforms_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
485 impl Iterator<Item=Ty<'tcx>> + 'a
487 self.upvar_tys(def_id, tcx).chain(iter::once(tcx.types.u32))
490 /// This is the types of all the fields stored in a generator.
491 /// It includes the upvars, state types and the state discriminant which is u32.
492 pub fn field_tys(self, def_id: DefId, tcx: TyCtxt<'a, 'gcx, 'tcx>) ->
493 impl Iterator<Item=Ty<'tcx>> + Captures<'gcx> + 'a
495 self.pre_transforms_tys(def_id, tcx).chain(self.state_tys(def_id, tcx))
499 #[derive(Debug, Copy, Clone)]
500 pub enum UpvarSubsts<'tcx> {
501 Closure(ClosureSubsts<'tcx>),
502 Generator(GeneratorSubsts<'tcx>),
505 impl<'tcx> UpvarSubsts<'tcx> {
507 pub fn upvar_tys(self, def_id: DefId, tcx: TyCtxt<'_, '_, '_>) ->
508 impl Iterator<Item=Ty<'tcx>> + 'tcx
510 let upvar_kinds = match self {
511 UpvarSubsts::Closure(substs) => substs.split(def_id, tcx).upvar_kinds,
512 UpvarSubsts::Generator(substs) => substs.split(def_id, tcx).upvar_kinds,
514 upvar_kinds.iter().map(|t| {
515 if let UnpackedKind::Type(ty) = t.unpack() {
518 bug!("upvar should be type")
524 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, RustcEncodable, RustcDecodable)]
525 pub enum ExistentialPredicate<'tcx> {
527 Trait(ExistentialTraitRef<'tcx>),
528 /// e.g. Iterator::Item = T
529 Projection(ExistentialProjection<'tcx>),
534 impl<'a, 'gcx, 'tcx> ExistentialPredicate<'tcx> {
535 /// Compares via an ordering that will not change if modules are reordered or other changes are
536 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
537 pub fn stable_cmp(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, other: &Self) -> Ordering {
538 use self::ExistentialPredicate::*;
539 match (*self, *other) {
540 (Trait(_), Trait(_)) => Ordering::Equal,
541 (Projection(ref a), Projection(ref b)) =>
542 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id)),
543 (AutoTrait(ref a), AutoTrait(ref b)) =>
544 tcx.trait_def(*a).def_path_hash.cmp(&tcx.trait_def(*b).def_path_hash),
545 (Trait(_), _) => Ordering::Less,
546 (Projection(_), Trait(_)) => Ordering::Greater,
547 (Projection(_), _) => Ordering::Less,
548 (AutoTrait(_), _) => Ordering::Greater,
554 impl<'a, 'gcx, 'tcx> Binder<ExistentialPredicate<'tcx>> {
555 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
556 -> ty::Predicate<'tcx> {
558 match *self.skip_binder() {
559 ExistentialPredicate::Trait(tr) => Binder(tr).with_self_ty(tcx, self_ty).to_predicate(),
560 ExistentialPredicate::Projection(p) =>
561 ty::Predicate::Projection(Binder(p.with_self_ty(tcx, self_ty))),
562 ExistentialPredicate::AutoTrait(did) => {
563 let trait_ref = Binder(ty::TraitRef {
565 substs: tcx.mk_substs_trait(self_ty, &[]),
567 trait_ref.to_predicate()
573 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List<ExistentialPredicate<'tcx>> {}
575 impl<'tcx> List<ExistentialPredicate<'tcx>> {
576 pub fn principal(&self) -> ExistentialTraitRef<'tcx> {
578 ExistentialPredicate::Trait(tr) => tr,
579 other => bug!("first predicate is {:?}", other),
584 pub fn projection_bounds<'a>(&'a self) ->
585 impl Iterator<Item=ExistentialProjection<'tcx>> + 'a {
586 self.iter().filter_map(|predicate| {
588 ExistentialPredicate::Projection(p) => Some(p),
595 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
596 self.iter().filter_map(|predicate| {
598 ExistentialPredicate::AutoTrait(d) => Some(d),
605 impl<'tcx> Binder<&'tcx List<ExistentialPredicate<'tcx>>> {
606 pub fn principal(&self) -> PolyExistentialTraitRef<'tcx> {
607 Binder::bind(self.skip_binder().principal())
611 pub fn projection_bounds<'a>(&'a self) ->
612 impl Iterator<Item=PolyExistentialProjection<'tcx>> + 'a {
613 self.skip_binder().projection_bounds().map(Binder::bind)
617 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item=DefId> + 'a {
618 self.skip_binder().auto_traits()
621 pub fn iter<'a>(&'a self)
622 -> impl DoubleEndedIterator<Item=Binder<ExistentialPredicate<'tcx>>> + 'tcx {
623 self.skip_binder().iter().cloned().map(Binder::bind)
627 /// A complete reference to a trait. These take numerous guises in syntax,
628 /// but perhaps the most recognizable form is in a where clause:
632 /// This would be represented by a trait-reference where the def-id is the
633 /// def-id for the trait `Foo` and the substs define `T` as parameter 0,
634 /// and `U` as parameter 1.
636 /// Trait references also appear in object types like `Foo<U>`, but in
637 /// that case the `Self` parameter is absent from the substitutions.
639 /// Note that a `TraitRef` introduces a level of region binding, to
640 /// account for higher-ranked trait bounds like `T : for<'a> Foo<&'a
641 /// U>` or higher-ranked object types.
642 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
643 pub struct TraitRef<'tcx> {
645 pub substs: &'tcx Substs<'tcx>,
648 impl<'tcx> TraitRef<'tcx> {
649 pub fn new(def_id: DefId, substs: &'tcx Substs<'tcx>) -> TraitRef<'tcx> {
650 TraitRef { def_id: def_id, substs: substs }
653 /// Returns a TraitRef of the form `P0: Foo<P1..Pn>` where `Pi`
654 /// are the parameters defined on trait.
655 pub fn identity<'a, 'gcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>, def_id: DefId) -> TraitRef<'tcx> {
658 substs: Substs::identity_for_item(tcx, def_id),
662 pub fn self_ty(&self) -> Ty<'tcx> {
663 self.substs.type_at(0)
666 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'a {
667 // Select only the "input types" from a trait-reference. For
668 // now this is all the types that appear in the
669 // trait-reference, but it should eventually exclude
674 pub fn from_method(tcx: TyCtxt<'_, '_, 'tcx>,
676 substs: &Substs<'tcx>)
677 -> ty::TraitRef<'tcx> {
678 let defs = tcx.generics_of(trait_id);
682 substs: tcx.intern_substs(&substs[..defs.params.len()])
687 pub type PolyTraitRef<'tcx> = Binder<TraitRef<'tcx>>;
689 impl<'tcx> PolyTraitRef<'tcx> {
690 pub fn self_ty(&self) -> Ty<'tcx> {
691 self.skip_binder().self_ty()
694 pub fn def_id(&self) -> DefId {
695 self.skip_binder().def_id
698 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
699 // Note that we preserve binding levels
700 Binder(ty::TraitPredicate { trait_ref: self.skip_binder().clone() })
704 /// An existential reference to a trait, where `Self` is erased.
705 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
707 /// exists T. T: Trait<'a, 'b, X, Y>
709 /// The substitutions don't include the erased `Self`, only trait
710 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
711 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
712 pub struct ExistentialTraitRef<'tcx> {
714 pub substs: &'tcx Substs<'tcx>,
717 impl<'a, 'gcx, 'tcx> ExistentialTraitRef<'tcx> {
718 pub fn input_types<'b>(&'b self) -> impl DoubleEndedIterator<Item=Ty<'tcx>> + 'b {
719 // Select only the "input types" from a trait-reference. For
720 // now this is all the types that appear in the
721 // trait-reference, but it should eventually exclude
726 pub fn erase_self_ty(tcx: TyCtxt<'a, 'gcx, 'tcx>,
727 trait_ref: ty::TraitRef<'tcx>)
728 -> ty::ExistentialTraitRef<'tcx> {
729 // Assert there is a Self.
730 trait_ref.substs.type_at(0);
732 ty::ExistentialTraitRef {
733 def_id: trait_ref.def_id,
734 substs: tcx.intern_substs(&trait_ref.substs[1..])
738 /// Object types don't have a self-type specified. Therefore, when
739 /// we convert the principal trait-ref into a normal trait-ref,
740 /// you must give *some* self-type. A common choice is `mk_err()`
741 /// or some placeholder type.
742 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
743 -> ty::TraitRef<'tcx> {
744 // otherwise the escaping vars would be captured by the binder
745 // debug_assert!(!self_ty.has_escaping_bound_vars());
749 substs: tcx.mk_substs_trait(self_ty, self.substs)
754 pub type PolyExistentialTraitRef<'tcx> = Binder<ExistentialTraitRef<'tcx>>;
756 impl<'tcx> PolyExistentialTraitRef<'tcx> {
757 pub fn def_id(&self) -> DefId {
758 self.skip_binder().def_id
761 /// Object types don't have a self-type specified. Therefore, when
762 /// we convert the principal trait-ref into a normal trait-ref,
763 /// you must give *some* self-type. A common choice is `mk_err()`
764 /// or some placeholder type.
765 pub fn with_self_ty(&self, tcx: TyCtxt<'_, '_, 'tcx>,
767 -> ty::PolyTraitRef<'tcx> {
768 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
772 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
773 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
774 /// (which would be represented by the type `PolyTraitRef ==
775 /// Binder<TraitRef>`). Note that when we instantiate,
776 /// erase, or otherwise "discharge" these bound vars, we change the
777 /// type from `Binder<T>` to just `T` (see
778 /// e.g. `liberate_late_bound_regions`).
779 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
780 pub struct Binder<T>(T);
783 /// Wraps `value` in a binder, asserting that `value` does not
784 /// contain any bound vars that would be bound by the
785 /// binder. This is commonly used to 'inject' a value T into a
786 /// different binding level.
787 pub fn dummy<'tcx>(value: T) -> Binder<T>
788 where T: TypeFoldable<'tcx>
790 debug_assert!(!value.has_escaping_bound_vars());
794 /// Wraps `value` in a binder, binding higher-ranked vars (if any).
795 pub fn bind<'tcx>(value: T) -> Binder<T> {
799 /// Skips the binder and returns the "bound" value. This is a
800 /// risky thing to do because it's easy to get confused about
801 /// debruijn indices and the like. It is usually better to
802 /// discharge the binder using `no_late_bound_regions` or
803 /// `replace_late_bound_regions` or something like
804 /// that. `skip_binder` is only valid when you are either
805 /// extracting data that has nothing to do with bound regions, you
806 /// are doing some sort of test that does not involve bound
807 /// regions, or you are being very careful about your depth
810 /// Some examples where `skip_binder` is reasonable:
812 /// - extracting the def-id from a PolyTraitRef;
813 /// - comparing the self type of a PolyTraitRef to see if it is equal to
814 /// a type parameter `X`, since the type `X` does not reference any regions
815 pub fn skip_binder(&self) -> &T {
819 pub fn as_ref(&self) -> Binder<&T> {
823 pub fn map_bound_ref<F, U>(&self, f: F) -> Binder<U>
824 where F: FnOnce(&T) -> U
826 self.as_ref().map_bound(f)
829 pub fn map_bound<F, U>(self, f: F) -> Binder<U>
830 where F: FnOnce(T) -> U
835 /// Unwraps and returns the value within, but only if it contains
836 /// no bound regions at all. (In other words, if this binder --
837 /// and indeed any enclosing binder -- doesn't bind anything at
838 /// all.) Otherwise, returns `None`.
840 /// (One could imagine having a method that just unwraps a single
841 /// binder, but permits late-bound regions bound by enclosing
842 /// binders, but that would require adjusting the debruijn
843 /// indices, and given the shallow binding structure we often use,
844 /// would not be that useful.)
845 pub fn no_late_bound_regions<'tcx>(self) -> Option<T>
846 where T : TypeFoldable<'tcx>
848 if self.skip_binder().has_escaping_bound_vars() {
851 Some(self.skip_binder().clone())
855 /// Given two things that have the same binder level,
856 /// and an operation that wraps on their contents, execute the operation
857 /// and then wrap its result.
859 /// `f` should consider bound regions at depth 1 to be free, and
860 /// anything it produces with bound regions at depth 1 will be
861 /// bound in the resulting return value.
862 pub fn fuse<U,F,R>(self, u: Binder<U>, f: F) -> Binder<R>
863 where F: FnOnce(T, U) -> R
865 Binder(f(self.0, u.0))
868 /// Split the contents into two things that share the same binder
869 /// level as the original, returning two distinct binders.
871 /// `f` should consider bound regions at depth 1 to be free, and
872 /// anything it produces with bound regions at depth 1 will be
873 /// bound in the resulting return values.
874 pub fn split<U,V,F>(self, f: F) -> (Binder<U>, Binder<V>)
875 where F: FnOnce(T) -> (U, V)
877 let (u, v) = f(self.0);
878 (Binder(u), Binder(v))
882 /// Represents the projection of an associated type. In explicit UFCS
883 /// form this would be written `<T as Trait<..>>::N`.
884 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
885 pub struct ProjectionTy<'tcx> {
886 /// The parameters of the associated item.
887 pub substs: &'tcx Substs<'tcx>,
889 /// The DefId of the TraitItem for the associated type N.
891 /// Note that this is not the DefId of the TraitRef containing this
892 /// associated type, which is in tcx.associated_item(item_def_id).container.
893 pub item_def_id: DefId,
896 impl<'a, 'tcx> ProjectionTy<'tcx> {
897 /// Construct a ProjectionTy by searching the trait from trait_ref for the
898 /// associated item named item_name.
899 pub fn from_ref_and_name(
900 tcx: TyCtxt<'_, '_, '_>, trait_ref: ty::TraitRef<'tcx>, item_name: Ident
901 ) -> ProjectionTy<'tcx> {
902 let item_def_id = tcx.associated_items(trait_ref.def_id).find(|item| {
903 item.kind == ty::AssociatedKind::Type &&
904 tcx.hygienic_eq(item_name, item.ident, trait_ref.def_id)
908 substs: trait_ref.substs,
913 /// Extracts the underlying trait reference from this projection.
914 /// For example, if this is a projection of `<T as Iterator>::Item`,
915 /// then this function would return a `T: Iterator` trait reference.
916 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::TraitRef<'tcx> {
917 let def_id = tcx.associated_item(self.item_def_id).container.id();
924 pub fn self_ty(&self) -> Ty<'tcx> {
925 self.substs.type_at(0)
929 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
930 pub struct GenSig<'tcx> {
931 pub yield_ty: Ty<'tcx>,
932 pub return_ty: Ty<'tcx>,
935 pub type PolyGenSig<'tcx> = Binder<GenSig<'tcx>>;
937 impl<'tcx> PolyGenSig<'tcx> {
938 pub fn yield_ty(&self) -> ty::Binder<Ty<'tcx>> {
939 self.map_bound_ref(|sig| sig.yield_ty)
941 pub fn return_ty(&self) -> ty::Binder<Ty<'tcx>> {
942 self.map_bound_ref(|sig| sig.return_ty)
946 /// Signature of a function type, which I have arbitrarily
947 /// decided to use to refer to the input/output types.
949 /// - `inputs` is the list of arguments and their modes.
950 /// - `output` is the return type.
951 /// - `variadic` indicates whether this is a variadic function. (only true for foreign fns)
952 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
953 pub struct FnSig<'tcx> {
954 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
956 pub unsafety: hir::Unsafety,
960 impl<'tcx> FnSig<'tcx> {
961 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
962 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
965 pub fn output(&self) -> Ty<'tcx> {
966 self.inputs_and_output[self.inputs_and_output.len() - 1]
970 pub type PolyFnSig<'tcx> = Binder<FnSig<'tcx>>;
972 impl<'tcx> PolyFnSig<'tcx> {
973 pub fn inputs(&self) -> Binder<&'tcx [Ty<'tcx>]> {
974 self.map_bound_ref(|fn_sig| fn_sig.inputs())
976 pub fn input(&self, index: usize) -> ty::Binder<Ty<'tcx>> {
977 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
979 pub fn inputs_and_output(&self) -> ty::Binder<&'tcx List<Ty<'tcx>>> {
980 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
982 pub fn output(&self) -> ty::Binder<Ty<'tcx>> {
983 self.map_bound_ref(|fn_sig| fn_sig.output())
985 pub fn variadic(&self) -> bool {
986 self.skip_binder().variadic
988 pub fn unsafety(&self) -> hir::Unsafety {
989 self.skip_binder().unsafety
991 pub fn abi(&self) -> abi::Abi {
992 self.skip_binder().abi
996 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<FnSig<'tcx>>>;
999 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1000 pub struct ParamTy {
1002 pub name: InternedString,
1005 impl<'a, 'gcx, 'tcx> ParamTy {
1006 pub fn new(index: u32, name: InternedString) -> ParamTy {
1007 ParamTy { idx: index, name: name }
1010 pub fn for_self() -> ParamTy {
1011 ParamTy::new(0, keywords::SelfType.name().as_interned_str())
1014 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1015 ParamTy::new(def.index, def.name)
1018 pub fn to_ty(self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1019 tcx.mk_ty_param(self.idx, self.name)
1022 pub fn is_self(&self) -> bool {
1023 // FIXME(#50125): Ignoring `Self` with `idx != 0` might lead to weird behavior elsewhere,
1024 // but this should only be possible when using `-Z continue-parse-after-error` like
1025 // `compile-fail/issue-36638.rs`.
1026 self.name == keywords::SelfType.name().as_str() && self.idx == 0
1030 /// A [De Bruijn index][dbi] is a standard means of representing
1031 /// regions (and perhaps later types) in a higher-ranked setting. In
1032 /// particular, imagine a type like this:
1034 /// for<'a> fn(for<'b> fn(&'b isize, &'a isize), &'a char)
1037 /// | +------------+ 0 | |
1039 /// +--------------------------------+ 1 |
1041 /// +------------------------------------------+ 0
1043 /// In this type, there are two binders (the outer fn and the inner
1044 /// fn). We need to be able to determine, for any given region, which
1045 /// fn type it is bound by, the inner or the outer one. There are
1046 /// various ways you can do this, but a De Bruijn index is one of the
1047 /// more convenient and has some nice properties. The basic idea is to
1048 /// count the number of binders, inside out. Some examples should help
1049 /// clarify what I mean.
1051 /// Let's start with the reference type `&'b isize` that is the first
1052 /// argument to the inner function. This region `'b` is assigned a De
1053 /// Bruijn index of 0, meaning "the innermost binder" (in this case, a
1054 /// fn). The region `'a` that appears in the second argument type (`&'a
1055 /// isize`) would then be assigned a De Bruijn index of 1, meaning "the
1056 /// second-innermost binder". (These indices are written on the arrays
1057 /// in the diagram).
1059 /// What is interesting is that De Bruijn index attached to a particular
1060 /// variable will vary depending on where it appears. For example,
1061 /// the final type `&'a char` also refers to the region `'a` declared on
1062 /// the outermost fn. But this time, this reference is not nested within
1063 /// any other binders (i.e., it is not an argument to the inner fn, but
1064 /// rather the outer one). Therefore, in this case, it is assigned a
1065 /// De Bruijn index of 0, because the innermost binder in that location
1066 /// is the outer fn.
1068 /// [dbi]: http://en.wikipedia.org/wiki/De_Bruijn_index
1070 pub struct DebruijnIndex {
1071 DEBUG_FORMAT = "DebruijnIndex({})",
1072 const INNERMOST = 0,
1076 pub type Region<'tcx> = &'tcx RegionKind;
1078 /// Representation of regions.
1080 /// Unlike types, most region variants are "fictitious", not concrete,
1081 /// regions. Among these, `ReStatic`, `ReEmpty` and `ReScope` are the only
1082 /// ones representing concrete regions.
1084 /// ## Bound Regions
1086 /// These are regions that are stored behind a binder and must be substituted
1087 /// with some concrete region before being used. There are 2 kind of
1088 /// bound regions: early-bound, which are bound in an item's Generics,
1089 /// and are substituted by a Substs, and late-bound, which are part of
1090 /// higher-ranked types (e.g. `for<'a> fn(&'a ())`) and are substituted by
1091 /// the likes of `liberate_late_bound_regions`. The distinction exists
1092 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1094 /// Unlike Param-s, bound regions are not supposed to exist "in the wild"
1095 /// outside their binder, e.g. in types passed to type inference, and
1096 /// should first be substituted (by placeholder regions, free regions,
1097 /// or region variables).
1099 /// ## Placeholder and Free Regions
1101 /// One often wants to work with bound regions without knowing their precise
1102 /// identity. For example, when checking a function, the lifetime of a borrow
1103 /// can end up being assigned to some region parameter. In these cases,
1104 /// it must be ensured that bounds on the region can't be accidentally
1105 /// assumed without being checked.
1107 /// To do this, we replace the bound regions with placeholder markers,
1108 /// which don't satisfy any relation not explicitly provided.
1110 /// There are 2 kinds of placeholder regions in rustc: `ReFree` and
1111 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1112 /// to be used. These also support explicit bounds: both the internally-stored
1113 /// *scope*, which the region is assumed to outlive, as well as other
1114 /// relations stored in the `FreeRegionMap`. Note that these relations
1115 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1116 /// `resolve_regions_and_report_errors`.
1118 /// When working with higher-ranked types, some region relations aren't
1119 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1120 /// `RePlaceholder` is designed for this purpose. In these contexts,
1121 /// there's also the risk that some inference variable laying around will
1122 /// get unified with your placeholder region: if you want to check whether
1123 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1124 /// with a placeholder region `'%a`, the variable `'_` would just be
1125 /// instantiated to the placeholder region `'%a`, which is wrong because
1126 /// the inference variable is supposed to satisfy the relation
1127 /// *for every value of the placeholder region*. To ensure that doesn't
1128 /// happen, you can use `leak_check`. This is more clearly explained
1129 /// by the [rustc guide].
1131 /// [1]: http://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1132 /// [2]: http://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1133 /// [rustc guide]: https://rust-lang-nursery.github.io/rustc-guide/traits/hrtb.html
1134 #[derive(Clone, PartialEq, Eq, Hash, Copy, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1135 pub enum RegionKind {
1136 // Region bound in a type or fn declaration which will be
1137 // substituted 'early' -- that is, at the same time when type
1138 // parameters are substituted.
1139 ReEarlyBound(EarlyBoundRegion),
1141 // Region bound in a function scope, which will be substituted when the
1142 // function is called.
1143 ReLateBound(DebruijnIndex, BoundRegion),
1145 /// When checking a function body, the types of all arguments and so forth
1146 /// that refer to bound region parameters are modified to refer to free
1147 /// region parameters.
1150 /// A concrete region naming some statically determined scope
1151 /// (e.g. an expression or sequence of statements) within the
1152 /// current function.
1153 ReScope(region::Scope),
1155 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1158 /// A region variable. Should not exist after typeck.
1161 /// A placeholder region - basically the higher-ranked version of ReFree.
1162 /// Should not exist after typeck.
1163 RePlaceholder(ty::Placeholder),
1165 /// Empty lifetime is for data that is never accessed.
1166 /// Bottom in the region lattice. We treat ReEmpty somewhat
1167 /// specially; at least right now, we do not generate instances of
1168 /// it during the GLB computations, but rather
1169 /// generate an error instead. This is to improve error messages.
1170 /// The only way to get an instance of ReEmpty is to have a region
1171 /// variable with no constraints.
1174 /// Erased region, used by trait selection, in MIR and during codegen.
1177 /// These are regions bound in the "defining type" for a
1178 /// closure. They are used ONLY as part of the
1179 /// `ClosureRegionRequirements` that are produced by MIR borrowck.
1180 /// See `ClosureRegionRequirements` for more details.
1181 ReClosureBound(RegionVid),
1184 impl<'tcx> serialize::UseSpecializedDecodable for Region<'tcx> {}
1186 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, Debug, PartialOrd, Ord)]
1187 pub struct EarlyBoundRegion {
1190 pub name: InternedString,
1193 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1198 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1203 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1204 pub struct FloatVid {
1209 pub struct RegionVid {
1210 DEBUG_FORMAT = custom,
1214 impl Atom for RegionVid {
1215 fn index(self) -> usize {
1220 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
1226 /// A `FreshTy` is one that is generated as a replacement for an
1227 /// unbound type variable. This is convenient for caching etc. See
1228 /// `infer::freshen` for more details.
1235 pub struct BoundVar { .. }
1238 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1239 pub struct BoundTy {
1240 pub index: DebruijnIndex,
1242 pub kind: BoundTyKind,
1245 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1246 pub enum BoundTyKind {
1248 Param(InternedString),
1251 impl_stable_hash_for!(struct BoundTy { index, var, kind });
1252 impl_stable_hash_for!(enum self::BoundTyKind { Anon, Param(a) });
1255 pub fn new(index: DebruijnIndex, var: BoundVar) -> Self {
1259 kind: BoundTyKind::Anon,
1264 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1265 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1266 pub struct ExistentialProjection<'tcx> {
1267 pub item_def_id: DefId,
1268 pub substs: &'tcx Substs<'tcx>,
1272 pub type PolyExistentialProjection<'tcx> = Binder<ExistentialProjection<'tcx>>;
1274 impl<'a, 'tcx, 'gcx> ExistentialProjection<'tcx> {
1275 /// Extracts the underlying existential trait reference from this projection.
1276 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1277 /// then this function would return a `exists T. T: Iterator` existential trait
1279 pub fn trait_ref(&self, tcx: TyCtxt<'_, '_, '_>) -> ty::ExistentialTraitRef<'tcx> {
1280 let def_id = tcx.associated_item(self.item_def_id).container.id();
1281 ty::ExistentialTraitRef{
1283 substs: self.substs,
1287 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
1289 -> ty::ProjectionPredicate<'tcx>
1291 // otherwise the escaping regions would be captured by the binders
1292 debug_assert!(!self_ty.has_escaping_bound_vars());
1294 ty::ProjectionPredicate {
1295 projection_ty: ty::ProjectionTy {
1296 item_def_id: self.item_def_id,
1297 substs: tcx.mk_substs_trait(self_ty, self.substs),
1304 impl<'a, 'tcx, 'gcx> PolyExistentialProjection<'tcx> {
1305 pub fn with_self_ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, self_ty: Ty<'tcx>)
1306 -> ty::PolyProjectionPredicate<'tcx> {
1307 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1310 pub fn item_def_id(&self) -> DefId {
1311 return self.skip_binder().item_def_id;
1315 impl DebruijnIndex {
1316 /// Returns the resulting index when this value is moved into
1317 /// `amount` number of new binders. So e.g. if you had
1319 /// for<'a> fn(&'a x)
1321 /// and you wanted to change to
1323 /// for<'a> fn(for<'b> fn(&'a x))
1325 /// you would need to shift the index for `'a` into 1 new binder.
1327 pub fn shifted_in(self, amount: u32) -> DebruijnIndex {
1328 DebruijnIndex::from_u32(self.as_u32() + amount)
1331 /// Update this index in place by shifting it "in" through
1332 /// `amount` number of binders.
1333 pub fn shift_in(&mut self, amount: u32) {
1334 *self = self.shifted_in(amount);
1337 /// Returns the resulting index when this value is moved out from
1338 /// `amount` number of new binders.
1340 pub fn shifted_out(self, amount: u32) -> DebruijnIndex {
1341 DebruijnIndex::from_u32(self.as_u32() - amount)
1344 /// Update in place by shifting out from `amount` binders.
1345 pub fn shift_out(&mut self, amount: u32) {
1346 *self = self.shifted_out(amount);
1349 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1350 /// innermost binder. That is, if we have something bound at `to_binder`,
1351 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1352 /// when moving a region out from inside binders:
1355 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1356 /// // Binder: D3 D2 D1 ^^
1359 /// Here, the region `'a` would have the debruijn index D3,
1360 /// because it is the bound 3 binders out. However, if we wanted
1361 /// to refer to that region `'a` in the second argument (the `_`),
1362 /// those two binders would not be in scope. In that case, we
1363 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1364 /// debruijn index of `'a` to D1 (the innermost binder).
1366 /// If we invoke `shift_out_to_binder` and the region is in fact
1367 /// bound by one of the binders we are shifting out of, that is an
1368 /// error (and should fail an assertion failure).
1369 pub fn shifted_out_to_binder(self, to_binder: DebruijnIndex) -> Self {
1370 self.shifted_out(to_binder.as_u32() - INNERMOST.as_u32())
1374 impl_stable_hash_for!(struct DebruijnIndex { private });
1376 /// Region utilities
1378 /// Is this region named by the user?
1379 pub fn has_name(&self) -> bool {
1381 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1382 RegionKind::ReLateBound(_, br) => br.is_named(),
1383 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1384 RegionKind::ReScope(..) => false,
1385 RegionKind::ReStatic => true,
1386 RegionKind::ReVar(..) => false,
1387 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1388 RegionKind::ReEmpty => false,
1389 RegionKind::ReErased => false,
1390 RegionKind::ReClosureBound(..) => false,
1394 pub fn is_late_bound(&self) -> bool {
1396 ty::ReLateBound(..) => true,
1401 pub fn bound_at_or_above_binder(&self, index: DebruijnIndex) -> bool {
1403 ty::ReLateBound(debruijn, _) => debruijn >= index,
1408 /// Adjusts any Debruijn Indices so as to make `to_binder` the
1409 /// innermost binder. That is, if we have something bound at `to_binder`,
1410 /// it will now be bound at INNERMOST. This is an appropriate thing to do
1411 /// when moving a region out from inside binders:
1414 /// for<'a> fn(for<'b> for<'c> fn(&'a u32), _)
1415 /// // Binder: D3 D2 D1 ^^
1418 /// Here, the region `'a` would have the debruijn index D3,
1419 /// because it is the bound 3 binders out. However, if we wanted
1420 /// to refer to that region `'a` in the second argument (the `_`),
1421 /// those two binders would not be in scope. In that case, we
1422 /// might invoke `shift_out_to_binder(D3)`. This would adjust the
1423 /// debruijn index of `'a` to D1 (the innermost binder).
1425 /// If we invoke `shift_out_to_binder` and the region is in fact
1426 /// bound by one of the binders we are shifting out of, that is an
1427 /// error (and should fail an assertion failure).
1428 pub fn shifted_out_to_binder(&self, to_binder: ty::DebruijnIndex) -> RegionKind {
1430 ty::ReLateBound(debruijn, r) => ty::ReLateBound(
1431 debruijn.shifted_out_to_binder(to_binder),
1438 pub fn keep_in_local_tcx(&self) -> bool {
1439 if let ty::ReVar(..) = self {
1446 pub fn type_flags(&self) -> TypeFlags {
1447 let mut flags = TypeFlags::empty();
1449 if self.keep_in_local_tcx() {
1450 flags = flags | TypeFlags::KEEP_IN_LOCAL_TCX;
1455 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1456 flags = flags | TypeFlags::HAS_RE_INFER;
1458 ty::RePlaceholder(..) => {
1459 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1460 flags = flags | TypeFlags::HAS_RE_SKOL;
1462 ty::ReLateBound(..) => {
1463 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1465 ty::ReEarlyBound(..) => {
1466 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1467 flags = flags | TypeFlags::HAS_RE_EARLY_BOUND;
1472 ty::ReScope { .. } => {
1473 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1477 ty::ReClosureBound(..) => {
1478 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1483 ty::ReStatic | ty::ReEmpty | ty::ReErased | ty::ReLateBound(..) => (),
1484 _ => flags = flags | TypeFlags::HAS_FREE_LOCAL_NAMES,
1487 debug!("type_flags({:?}) = {:?}", self, flags);
1492 /// Given an early-bound or free region, returns the def-id where it was bound.
1493 /// For example, consider the regions in this snippet of code:
1497 /// ^^ -- early bound, declared on an impl
1499 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1500 /// ^^ ^^ ^ anonymous, late-bound
1501 /// | early-bound, appears in where-clauses
1502 /// late-bound, appears only in fn args
1507 /// Here, `free_region_binding_scope('a)` would return the def-id
1508 /// of the impl, and for all the other highlighted regions, it
1509 /// would return the def-id of the function. In other cases (not shown), this
1510 /// function might return the def-id of a closure.
1511 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_, '_, '_>) -> DefId {
1513 ty::ReEarlyBound(br) => {
1514 tcx.parent_def_id(br.def_id).unwrap()
1516 ty::ReFree(fr) => fr.scope,
1517 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1523 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
1524 pub fn is_unit(&self) -> bool {
1526 Tuple(ref tys) => tys.is_empty(),
1531 pub fn is_never(&self) -> bool {
1538 pub fn is_primitive(&self) -> bool {
1540 Bool | Char | Int(_) | Uint(_) | Float(_) => true,
1545 pub fn is_ty_var(&self) -> bool {
1547 Infer(TyVar(_)) => true,
1552 pub fn is_ty_infer(&self) -> bool {
1559 pub fn is_phantom_data(&self) -> bool {
1560 if let Adt(def, _) = self.sty {
1561 def.is_phantom_data()
1567 pub fn is_bool(&self) -> bool { self.sty == Bool }
1569 pub fn is_param(&self, index: u32) -> bool {
1571 ty::Param(ref data) => data.idx == index,
1576 pub fn is_self(&self) -> bool {
1578 Param(ref p) => p.is_self(),
1583 pub fn is_slice(&self) -> bool {
1585 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => match ty.sty {
1586 Slice(_) | Str => true,
1594 pub fn is_simd(&self) -> bool {
1596 Adt(def, _) => def.repr.simd(),
1601 pub fn sequence_element_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1603 Array(ty, _) | Slice(ty) => ty,
1604 Str => tcx.mk_mach_uint(ast::UintTy::U8),
1605 _ => bug!("sequence_element_type called on non-sequence value: {}", self),
1609 pub fn simd_type(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Ty<'tcx> {
1611 Adt(def, substs) => {
1612 def.non_enum_variant().fields[0].ty(tcx, substs)
1614 _ => bug!("simd_type called on invalid type")
1618 pub fn simd_size(&self, _cx: TyCtxt<'_, '_, '_>) -> usize {
1620 Adt(def, _) => def.non_enum_variant().fields.len(),
1621 _ => bug!("simd_size called on invalid type")
1625 pub fn is_region_ptr(&self) -> bool {
1632 pub fn is_mutable_pointer(&self) -> bool {
1634 RawPtr(TypeAndMut { mutbl: hir::Mutability::MutMutable, .. }) |
1635 Ref(_, _, hir::Mutability::MutMutable) => true,
1640 pub fn is_unsafe_ptr(&self) -> bool {
1642 RawPtr(_) => return true,
1647 /// Returns `true` if this type is an `Arc<T>`.
1648 pub fn is_arc(&self) -> bool {
1650 Adt(def, _) => def.is_arc(),
1655 /// Returns `true` if this type is an `Rc<T>`.
1656 pub fn is_rc(&self) -> bool {
1658 Adt(def, _) => def.is_rc(),
1663 pub fn is_box(&self) -> bool {
1665 Adt(def, _) => def.is_box(),
1670 /// panics if called on any type other than `Box<T>`
1671 pub fn boxed_ty(&self) -> Ty<'tcx> {
1673 Adt(def, substs) if def.is_box() => substs.type_at(0),
1674 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1678 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1679 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1680 /// contents are abstract to rustc.)
1681 pub fn is_scalar(&self) -> bool {
1683 Bool | Char | Int(_) | Float(_) | Uint(_) |
1684 Infer(IntVar(_)) | Infer(FloatVar(_)) |
1685 FnDef(..) | FnPtr(_) | RawPtr(_) => true,
1690 /// Returns true if this type is a floating point type and false otherwise.
1691 pub fn is_floating_point(&self) -> bool {
1694 Infer(FloatVar(_)) => true,
1699 pub fn is_trait(&self) -> bool {
1701 Dynamic(..) => true,
1706 pub fn is_enum(&self) -> bool {
1708 Adt(adt_def, _) => {
1715 pub fn is_closure(&self) -> bool {
1717 Closure(..) => true,
1722 pub fn is_generator(&self) -> bool {
1724 Generator(..) => true,
1729 pub fn is_integral(&self) -> bool {
1731 Infer(IntVar(_)) | Int(_) | Uint(_) => true,
1736 pub fn is_fresh_ty(&self) -> bool {
1738 Infer(FreshTy(_)) => true,
1743 pub fn is_fresh(&self) -> bool {
1745 Infer(FreshTy(_)) => true,
1746 Infer(FreshIntTy(_)) => true,
1747 Infer(FreshFloatTy(_)) => true,
1752 pub fn is_char(&self) -> bool {
1759 pub fn is_fp(&self) -> bool {
1761 Infer(FloatVar(_)) | Float(_) => true,
1766 pub fn is_numeric(&self) -> bool {
1767 self.is_integral() || self.is_fp()
1770 pub fn is_signed(&self) -> bool {
1777 pub fn is_machine(&self) -> bool {
1779 Int(ast::IntTy::Isize) | Uint(ast::UintTy::Usize) => false,
1780 Int(..) | Uint(..) | Float(..) => true,
1785 pub fn has_concrete_skeleton(&self) -> bool {
1787 Param(_) | Infer(_) | Error => false,
1792 /// Returns the type and mutability of *ty.
1794 /// The parameter `explicit` indicates if this is an *explicit* dereference.
1795 /// Some types---notably unsafe ptrs---can only be dereferenced explicitly.
1796 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
1798 Adt(def, _) if def.is_box() => {
1800 ty: self.boxed_ty(),
1801 mutbl: hir::MutImmutable,
1804 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl }),
1805 RawPtr(mt) if explicit => Some(mt),
1810 /// Returns the type of `ty[i]`.
1811 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
1813 Array(ty, _) | Slice(ty) => Some(ty),
1818 pub fn fn_sig(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> PolyFnSig<'tcx> {
1820 FnDef(def_id, substs) => {
1821 tcx.fn_sig(def_id).subst(tcx, substs)
1824 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self)
1828 pub fn is_fn(&self) -> bool {
1830 FnDef(..) | FnPtr(_) => true,
1835 pub fn is_impl_trait(&self) -> bool {
1842 pub fn ty_adt_def(&self) -> Option<&'tcx AdtDef> {
1844 Adt(adt, _) => Some(adt),
1849 /// Returns the regions directly referenced from this type (but
1850 /// not types reachable from this type via `walk_tys`). This
1851 /// ignores late-bound regions binders.
1852 pub fn regions(&self) -> Vec<ty::Region<'tcx>> {
1854 Ref(region, _, _) => {
1857 Dynamic(ref obj, region) => {
1858 let mut v = vec![region];
1859 v.extend(obj.principal().skip_binder().substs.regions());
1862 Adt(_, substs) | Opaque(_, substs) => {
1863 substs.regions().collect()
1865 Closure(_, ClosureSubsts { ref substs }) |
1866 Generator(_, GeneratorSubsts { ref substs }, _) => {
1867 substs.regions().collect()
1869 Projection(ref data) | UnnormalizedProjection(ref data) => {
1870 data.substs.regions().collect()
1874 GeneratorWitness(..) |
1896 /// When we create a closure, we record its kind (i.e., what trait
1897 /// it implements) into its `ClosureSubsts` using a type
1898 /// parameter. This is kind of a phantom type, except that the
1899 /// most convenient thing for us to are the integral types. This
1900 /// function converts such a special type into the closure
1901 /// kind. To go the other way, use
1902 /// `tcx.closure_kind_ty(closure_kind)`.
1904 /// Note that during type checking, we use an inference variable
1905 /// to represent the closure kind, because it has not yet been
1906 /// inferred. Once upvar inference (in `src/librustc_typeck/check/upvar.rs`)
1907 /// is complete, that type variable will be unified.
1908 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
1910 Int(int_ty) => match int_ty {
1911 ast::IntTy::I8 => Some(ty::ClosureKind::Fn),
1912 ast::IntTy::I16 => Some(ty::ClosureKind::FnMut),
1913 ast::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
1914 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1919 Error => Some(ty::ClosureKind::Fn),
1921 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
1925 /// Fast path helper for testing if a type is `Sized`.
1927 /// Returning true means the type is known to be sized. Returning
1928 /// `false` means nothing -- could be sized, might not be.
1929 pub fn is_trivially_sized(&self, tcx: TyCtxt<'_, '_, 'tcx>) -> bool {
1931 ty::Infer(ty::IntVar(_)) | ty::Infer(ty::FloatVar(_)) |
1932 ty::Uint(_) | ty::Int(_) | ty::Bool | ty::Float(_) |
1933 ty::FnDef(..) | ty::FnPtr(_) | ty::RawPtr(..) |
1934 ty::Char | ty::Ref(..) | ty::Generator(..) |
1935 ty::GeneratorWitness(..) | ty::Array(..) | ty::Closure(..) |
1936 ty::Never | ty::Error =>
1939 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) =>
1943 tys.iter().all(|ty| ty.is_trivially_sized(tcx)),
1945 ty::Adt(def, _substs) =>
1946 def.sized_constraint(tcx).is_empty(),
1948 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
1950 ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
1952 ty::Infer(ty::TyVar(_)) => false,
1955 ty::Infer(ty::FreshTy(_)) |
1956 ty::Infer(ty::FreshIntTy(_)) |
1957 ty::Infer(ty::FreshFloatTy(_)) =>
1958 bug!("is_trivially_sized applied to unexpected type: {:?}", self),
1963 /// Typed constant value.
1964 #[derive(Copy, Clone, Debug, Hash, RustcEncodable, RustcDecodable, Eq, PartialEq, Ord, PartialOrd)]
1965 pub struct Const<'tcx> {
1968 pub val: ConstValue<'tcx>,
1971 impl<'tcx> Const<'tcx> {
1973 tcx: TyCtxt<'_, '_, 'tcx>,
1975 substs: &'tcx Substs<'tcx>,
1978 tcx.mk_const(Const {
1979 val: ConstValue::Unevaluated(def_id, substs),
1985 pub fn from_const_value(
1986 tcx: TyCtxt<'_, '_, 'tcx>,
1987 val: ConstValue<'tcx>,
1990 tcx.mk_const(Const {
1998 tcx: TyCtxt<'_, '_, 'tcx>,
2002 Self::from_const_value(tcx, ConstValue::Scalar(val), ty)
2007 tcx: TyCtxt<'_, '_, 'tcx>,
2009 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2011 let ty = tcx.lift_to_global(&ty).unwrap();
2012 let size = tcx.layout_of(ty).unwrap_or_else(|e| {
2013 panic!("could not compute layout for {:?}: {:?}", ty, e)
2015 let shift = 128 - size.bits();
2016 let truncated = (bits << shift) >> shift;
2017 assert_eq!(truncated, bits, "from_bits called with untruncated value");
2018 Self::from_scalar(tcx, Scalar::Bits { bits, size: size.bytes() as u8 }, ty.value)
2022 pub fn zero_sized(tcx: TyCtxt<'_, '_, 'tcx>, ty: Ty<'tcx>) -> &'tcx Self {
2023 Self::from_scalar(tcx, Scalar::Bits { bits: 0, size: 0 }, ty)
2027 pub fn from_bool(tcx: TyCtxt<'_, '_, 'tcx>, v: bool) -> &'tcx Self {
2028 Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
2032 pub fn from_usize(tcx: TyCtxt<'_, '_, 'tcx>, n: u64) -> &'tcx Self {
2033 Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
2039 tcx: TyCtxt<'_, '_, 'tcx>,
2040 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2042 if self.ty != ty.value {
2045 let ty = tcx.lift_to_global(&ty).unwrap();
2046 let size = tcx.layout_of(ty).ok()?.size;
2047 self.val.try_to_bits(size)
2051 pub fn to_ptr(&self) -> Option<Pointer> {
2052 self.val.try_to_ptr()
2058 tcx: TyCtxt<'_, '_, '_>,
2059 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2061 assert_eq!(self.ty, ty.value);
2062 let ty = tcx.lift_to_global(&ty).unwrap();
2063 let size = tcx.layout_of(ty).ok()?.size;
2064 self.val.try_to_bits(size)
2068 pub fn assert_bool(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<bool> {
2069 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.bool)).and_then(|v| match v {
2077 pub fn assert_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> Option<u64> {
2078 self.assert_bits(tcx, ParamEnv::empty().and(tcx.types.usize)).map(|v| v as u64)
2084 tcx: TyCtxt<'_, '_, '_>,
2085 ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
2087 self.assert_bits(tcx, ty).unwrap_or_else(||
2088 bug!("expected bits of {}, got {:#?}", ty.value, self))
2092 pub fn unwrap_usize(&self, tcx: TyCtxt<'_, '_, '_>) -> u64 {
2093 self.assert_usize(tcx).unwrap_or_else(||
2094 bug!("expected constant usize, got {:#?}", self))
2098 impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}