1 //! This module contains `TyKind` and its major components.
3 #![allow(rustc::usage_of_ty_tykind)]
7 use crate::infer::canonical::Canonical;
8 use crate::ty::fold::ValidateBoundVars;
9 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
10 use crate::ty::InferTy::{self, *};
11 use crate::ty::{self, AdtDef, DefIdTree, Discr, Term, Ty, TyCtxt, TypeFlags, TypeFoldable};
12 use crate::ty::{DelaySpanBugEmitted, List, ParamEnv, TyS};
13 use polonius_engine::Atom;
14 use rustc_data_structures::captures::Captures;
16 use rustc_hir::def_id::DefId;
17 use rustc_index::vec::Idx;
18 use rustc_macros::HashStable;
19 use rustc_span::symbol::{kw, Symbol};
20 use rustc_target::abi::VariantIdx;
21 use rustc_target::spec::abi;
23 use std::cmp::Ordering;
24 use std::marker::PhantomData;
26 use ty::util::IntTypeExt;
28 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
29 #[derive(HashStable, TypeFoldable, Lift)]
30 pub struct TypeAndMut<'tcx> {
32 pub mutbl: hir::Mutability,
35 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
37 /// A "free" region `fr` can be interpreted as "some region
38 /// at least as big as the scope `fr.scope`".
39 pub struct FreeRegion {
41 pub bound_region: BoundRegionKind,
44 #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, TyEncodable, TyDecodable, Copy)]
46 pub enum BoundRegionKind {
47 /// An anonymous region parameter for a given fn (&T)
50 /// Named region parameters for functions (a in &'a T)
52 /// The `DefId` is needed to distinguish free regions in
53 /// the event of shadowing.
54 BrNamed(DefId, Symbol),
56 /// Anonymous region for the implicit env pointer parameter
61 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
63 pub struct BoundRegion {
65 pub kind: BoundRegionKind,
68 impl BoundRegionKind {
69 pub fn is_named(&self) -> bool {
71 BoundRegionKind::BrNamed(_, name) => name != kw::UnderscoreLifetime,
77 /// Defines the kinds of types used by the type system.
79 /// Types written by the user start out as [hir::TyKind](rustc_hir::TyKind) and get
80 /// converted to this representation using `AstConv::ast_ty_to_ty`.
81 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable, Debug)]
83 #[rustc_diagnostic_item = "TyKind"]
84 pub enum TyKind<'tcx> {
85 /// The primitive boolean type. Written as `bool`.
88 /// The primitive character type; holds a Unicode scalar value
89 /// (a non-surrogate code point). Written as `char`.
92 /// A primitive signed integer type. For example, `i32`.
95 /// A primitive unsigned integer type. For example, `u32`.
98 /// A primitive floating-point type. For example, `f64`.
101 /// Algebraic data types (ADT). For example: structures, enumerations and unions.
103 /// For example, the type `List<i32>` would be represented using the `AdtDef`
104 /// for `struct List<T>` and the substs `[i32]`.
106 /// Note that generic parameters in fields only get lazily substituted
107 /// by using something like `adt_def.all_fields().map(|field| field.ty(tcx, substs))`.
108 Adt(&'tcx AdtDef, SubstsRef<'tcx>),
110 /// An unsized FFI type that is opaque to Rust. Written as `extern type T`.
113 /// The pointee of a string slice. Written as `str`.
116 /// An array with the given length. Written as `[T; N]`.
117 Array(Ty<'tcx>, &'tcx ty::Const<'tcx>),
119 /// The pointee of an array slice. Written as `[T]`.
122 /// A raw pointer. Written as `*mut T` or `*const T`
123 RawPtr(TypeAndMut<'tcx>),
125 /// A reference; a pointer with an associated lifetime. Written as
126 /// `&'a mut T` or `&'a T`.
127 Ref(Region<'tcx>, Ty<'tcx>, hir::Mutability),
129 /// The anonymous type of a function declaration/definition. Each
130 /// function has a unique type.
132 /// For the function `fn foo() -> i32 { 3 }` this type would be
133 /// shown to the user as `fn() -> i32 {foo}`.
135 /// For example the type of `bar` here:
137 /// fn foo() -> i32 { 1 }
138 /// let bar = foo; // bar: fn() -> i32 {foo}
140 FnDef(DefId, SubstsRef<'tcx>),
142 /// A pointer to a function. Written as `fn() -> i32`.
144 /// Note that both functions and closures start out as either
145 /// [FnDef] or [Closure] which can be then be coerced to this variant.
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 object. Written as `dyn for<'b> Trait<'b, Assoc = u32> + Send + 'a`.
156 Dynamic(&'tcx List<Binder<'tcx, ExistentialPredicate<'tcx>>>, ty::Region<'tcx>),
158 /// The anonymous type of a closure. Used to represent the type of `|a| a`.
160 /// Closure substs contain both the - potentially substituted - generic parameters
161 /// of its parent and some synthetic parameters. See the documentation for
162 /// [ClosureSubsts] for more details.
163 Closure(DefId, SubstsRef<'tcx>),
165 /// The anonymous type of a generator. Used to represent the type of
168 /// For more info about generator substs, visit the documentation for
169 /// [GeneratorSubsts].
170 Generator(DefId, SubstsRef<'tcx>, hir::Movability),
172 /// A type representing the types stored inside a generator.
173 /// This should only appear as part of the [GeneratorSubsts].
175 /// Note that the captured variables for generators are stored separately
176 /// using a tuple in the same way as for closures.
178 /// Unlike upvars, the witness can reference lifetimes from
179 /// inside of the generator itself. To deal with them in
180 /// the type of the generator, we convert them to higher ranked
181 /// lifetimes bound by the witness itself.
183 /// Looking at the following example, the witness for this generator
184 /// may end up as something like `for<'a> [Vec<i32>, &'a Vec<i32>]`:
188 /// let x = &vec![3];
193 GeneratorWitness(Binder<'tcx, &'tcx List<Ty<'tcx>>>),
195 /// The never type `!`.
198 /// A tuple type. For example, `(i32, bool)`.
199 /// Use `TyS::tuple_fields` to iterate over the field types.
200 Tuple(SubstsRef<'tcx>),
202 /// The projection of an associated type. For example,
203 /// `<T as Trait<..>>::N`.
204 Projection(ProjectionTy<'tcx>),
206 /// Opaque (`impl Trait`) type found in a return type.
208 /// The `DefId` comes either from
209 /// * the `impl Trait` ast::Ty node,
210 /// * or the `type Foo = impl Trait` declaration
212 /// For RPIT the substitutions are for the generics of the function,
213 /// while for TAIT it is used for the generic parameters of the alias.
215 /// During codegen, `tcx.type_of(def_id)` can be used to get the underlying type.
216 Opaque(DefId, SubstsRef<'tcx>),
218 /// A type parameter; for example, `T` in `fn f<T>(x: T) {}`.
221 /// Bound type variable, used to represent the `'a` in `for<'a> fn(&'a ())`.
223 /// For canonical queries, we replace inference variables with bound variables,
224 /// so e.g. when checking whether `&'_ (): Trait<_>` holds, we canonicalize that to
225 /// `for<'a, T> &'a (): Trait<T>` and then convert the introduced bound variables
226 /// back to inference variables in a new inference context when inside of the query.
228 /// See the `rustc-dev-guide` for more details about
229 /// [higher-ranked trait bounds][1] and [canonical queries][2].
231 /// [1]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
232 /// [2]: https://rustc-dev-guide.rust-lang.org/traits/canonical-queries.html
233 Bound(ty::DebruijnIndex, BoundTy),
235 /// A placeholder type, used during higher ranked subtyping to instantiate
237 Placeholder(ty::PlaceholderType),
239 /// A type variable used during type checking.
241 /// Similar to placeholders, inference variables also live in a universe to
242 /// correctly deal with higher ranked types. Though unlike placeholders,
243 /// that universe is stored in the `InferCtxt` instead of directly
244 /// inside of the type.
247 /// A placeholder for a type which could not be computed; this is
248 /// propagated to avoid useless error messages.
249 Error(DelaySpanBugEmitted),
252 impl<'tcx> TyKind<'tcx> {
254 pub fn is_primitive(&self) -> bool {
255 matches!(self, Bool | Char | Int(_) | Uint(_) | Float(_))
258 /// Get the article ("a" or "an") to use with this type.
259 pub fn article(&self) -> &'static str {
261 Int(_) | Float(_) | Array(_, _) => "an",
262 Adt(def, _) if def.is_enum() => "an",
263 // This should never happen, but ICEing and causing the user's code
264 // to not compile felt too harsh.
271 // `TyKind` is used a lot. Make sure it doesn't unintentionally get bigger.
272 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
273 static_assert_size!(TyKind<'_>, 32);
275 /// A closure can be modeled as a struct that looks like:
277 /// struct Closure<'l0...'li, T0...Tj, CK, CS, U>(...U);
281 /// - 'l0...'li and T0...Tj are the generic parameters
282 /// in scope on the function that defined the closure,
283 /// - CK represents the *closure kind* (Fn vs FnMut vs FnOnce). This
284 /// is rather hackily encoded via a scalar type. See
285 /// `TyS::to_opt_closure_kind` for details.
286 /// - CS represents the *closure signature*, representing as a `fn()`
287 /// type. For example, `fn(u32, u32) -> u32` would mean that the closure
288 /// implements `CK<(u32, u32), Output = u32>`, where `CK` is the trait
290 /// - U is a type parameter representing the types of its upvars, tupled up
291 /// (borrowed, if appropriate; that is, if a U field represents a by-ref upvar,
292 /// and the up-var has the type `Foo`, then that field of U will be `&Foo`).
294 /// So, for example, given this function:
296 /// fn foo<'a, T>(data: &'a mut T) {
297 /// do(|| data.count += 1)
300 /// the type of the closure would be something like:
302 /// struct Closure<'a, T, U>(...U);
304 /// Note that the type of the upvar is not specified in the struct.
305 /// You may wonder how the impl would then be able to use the upvar,
306 /// if it doesn't know it's type? The answer is that the impl is
307 /// (conceptually) not fully generic over Closure but rather tied to
308 /// instances with the expected upvar types:
310 /// impl<'b, 'a, T> FnMut() for Closure<'a, T, (&'b mut &'a mut T,)> {
314 /// You can see that the *impl* fully specified the type of the upvar
315 /// and thus knows full well that `data` has type `&'b mut &'a mut T`.
316 /// (Here, I am assuming that `data` is mut-borrowed.)
318 /// Now, the last question you may ask is: Why include the upvar types
319 /// in an extra type parameter? The reason for this design is that the
320 /// upvar types can reference lifetimes that are internal to the
321 /// creating function. In my example above, for example, the lifetime
322 /// `'b` represents the scope of the closure itself; this is some
323 /// subset of `foo`, probably just the scope of the call to the to
324 /// `do()`. If we just had the lifetime/type parameters from the
325 /// enclosing function, we couldn't name this lifetime `'b`. Note that
326 /// there can also be lifetimes in the types of the upvars themselves,
327 /// if one of them happens to be a reference to something that the
328 /// creating fn owns.
330 /// OK, you say, so why not create a more minimal set of parameters
331 /// that just includes the extra lifetime parameters? The answer is
332 /// primarily that it would be hard --- we don't know at the time when
333 /// we create the closure type what the full types of the upvars are,
334 /// nor do we know which are borrowed and which are not. In this
335 /// design, we can just supply a fresh type parameter and figure that
338 /// All right, you say, but why include the type parameters from the
339 /// original function then? The answer is that codegen may need them
340 /// when monomorphizing, and they may not appear in the upvars. A
341 /// closure could capture no variables but still make use of some
342 /// in-scope type parameter with a bound (e.g., if our example above
343 /// had an extra `U: Default`, and the closure called `U::default()`).
345 /// There is another reason. This design (implicitly) prohibits
346 /// closures from capturing themselves (except via a trait
347 /// object). This simplifies closure inference considerably, since it
348 /// means that when we infer the kind of a closure or its upvars, we
349 /// don't have to handle cycles where the decisions we make for
350 /// closure C wind up influencing the decisions we ought to make for
351 /// closure C (which would then require fixed point iteration to
352 /// handle). Plus it fixes an ICE. :P
356 /// Generators are handled similarly in `GeneratorSubsts`. The set of
357 /// type parameters is similar, but `CK` and `CS` are replaced by the
358 /// following type parameters:
360 /// * `GS`: The generator's "resume type", which is the type of the
361 /// argument passed to `resume`, and the type of `yield` expressions
362 /// inside the generator.
363 /// * `GY`: The "yield type", which is the type of values passed to
364 /// `yield` inside the generator.
365 /// * `GR`: The "return type", which is the type of value returned upon
366 /// completion of the generator.
367 /// * `GW`: The "generator witness".
368 #[derive(Copy, Clone, Debug, TypeFoldable)]
369 pub struct ClosureSubsts<'tcx> {
370 /// Lifetime and type parameters from the enclosing function,
371 /// concatenated with a tuple containing the types of the upvars.
373 /// These are separated out because codegen wants to pass them around
374 /// when monomorphizing.
375 pub substs: SubstsRef<'tcx>,
378 /// Struct returned by `split()`.
379 pub struct ClosureSubstsParts<'tcx, T> {
380 pub parent_substs: &'tcx [GenericArg<'tcx>],
381 pub closure_kind_ty: T,
382 pub closure_sig_as_fn_ptr_ty: T,
383 pub tupled_upvars_ty: T,
386 impl<'tcx> ClosureSubsts<'tcx> {
387 /// Construct `ClosureSubsts` from `ClosureSubstsParts`, containing `Substs`
388 /// for the closure parent, alongside additional closure-specific components.
391 parts: ClosureSubstsParts<'tcx, Ty<'tcx>>,
392 ) -> ClosureSubsts<'tcx> {
394 substs: tcx.mk_substs(
395 parts.parent_substs.iter().copied().chain(
396 [parts.closure_kind_ty, parts.closure_sig_as_fn_ptr_ty, parts.tupled_upvars_ty]
398 .map(|&ty| ty.into()),
404 /// Divides the closure substs into their respective components.
405 /// The ordering assumed here must match that used by `ClosureSubsts::new` above.
406 fn split(self) -> ClosureSubstsParts<'tcx, GenericArg<'tcx>> {
407 match self.substs[..] {
409 ref parent_substs @ ..,
411 closure_sig_as_fn_ptr_ty,
413 ] => ClosureSubstsParts {
416 closure_sig_as_fn_ptr_ty,
419 _ => bug!("closure substs missing synthetics"),
423 /// Returns `true` only if enough of the synthetic types are known to
424 /// allow using all of the methods on `ClosureSubsts` without panicking.
426 /// Used primarily by `ty::print::pretty` to be able to handle closure
427 /// types that haven't had their synthetic types substituted in.
428 pub fn is_valid(self) -> bool {
429 self.substs.len() >= 3
430 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
433 /// Returns the substitutions of the closure's parent.
434 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
435 self.split().parent_substs
438 /// Returns an iterator over the list of types of captured paths by the closure.
439 /// In case there was a type error in figuring out the types of the captured path, an
440 /// empty iterator is returned.
442 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
443 match self.tupled_upvars_ty().kind() {
444 TyKind::Error(_) => None,
445 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
446 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
447 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
453 /// Returns the tuple type representing the upvars for this closure.
455 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
456 self.split().tupled_upvars_ty.expect_ty()
459 /// Returns the closure kind for this closure; may return a type
460 /// variable during inference. To get the closure kind during
461 /// inference, use `infcx.closure_kind(substs)`.
462 pub fn kind_ty(self) -> Ty<'tcx> {
463 self.split().closure_kind_ty.expect_ty()
466 /// Returns the `fn` pointer type representing the closure signature for this
468 // FIXME(eddyb) this should be unnecessary, as the shallowly resolved
469 // type is known at the time of the creation of `ClosureSubsts`,
470 // see `rustc_typeck::check::closure`.
471 pub fn sig_as_fn_ptr_ty(self) -> Ty<'tcx> {
472 self.split().closure_sig_as_fn_ptr_ty.expect_ty()
475 /// Returns the closure kind for this closure; only usable outside
476 /// of an inference context, because in that context we know that
477 /// there are no type variables.
479 /// If you have an inference context, use `infcx.closure_kind()`.
480 pub fn kind(self) -> ty::ClosureKind {
481 self.kind_ty().to_opt_closure_kind().unwrap()
484 /// Extracts the signature from the closure.
485 pub fn sig(self) -> ty::PolyFnSig<'tcx> {
486 let ty = self.sig_as_fn_ptr_ty();
488 ty::FnPtr(sig) => *sig,
489 _ => bug!("closure_sig_as_fn_ptr_ty is not a fn-ptr: {:?}", ty.kind()),
494 /// Similar to `ClosureSubsts`; see the above documentation for more.
495 #[derive(Copy, Clone, Debug, TypeFoldable)]
496 pub struct GeneratorSubsts<'tcx> {
497 pub substs: SubstsRef<'tcx>,
500 pub struct GeneratorSubstsParts<'tcx, T> {
501 pub parent_substs: &'tcx [GenericArg<'tcx>],
506 pub tupled_upvars_ty: T,
509 impl<'tcx> GeneratorSubsts<'tcx> {
510 /// Construct `GeneratorSubsts` from `GeneratorSubstsParts`, containing `Substs`
511 /// for the generator parent, alongside additional generator-specific components.
514 parts: GeneratorSubstsParts<'tcx, Ty<'tcx>>,
515 ) -> GeneratorSubsts<'tcx> {
517 substs: tcx.mk_substs(
518 parts.parent_substs.iter().copied().chain(
524 parts.tupled_upvars_ty,
527 .map(|&ty| ty.into()),
533 /// Divides the generator substs into their respective components.
534 /// The ordering assumed here must match that used by `GeneratorSubsts::new` above.
535 fn split(self) -> GeneratorSubstsParts<'tcx, GenericArg<'tcx>> {
536 match self.substs[..] {
537 [ref parent_substs @ .., resume_ty, yield_ty, return_ty, witness, tupled_upvars_ty] => {
538 GeneratorSubstsParts {
547 _ => bug!("generator substs missing synthetics"),
551 /// Returns `true` only if enough of the synthetic types are known to
552 /// allow using all of the methods on `GeneratorSubsts` without panicking.
554 /// Used primarily by `ty::print::pretty` to be able to handle generator
555 /// types that haven't had their synthetic types substituted in.
556 pub fn is_valid(self) -> bool {
557 self.substs.len() >= 5
558 && matches!(self.split().tupled_upvars_ty.expect_ty().kind(), Tuple(_))
561 /// Returns the substitutions of the generator's parent.
562 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
563 self.split().parent_substs
566 /// This describes the types that can be contained in a generator.
567 /// It will be a type variable initially and unified in the last stages of typeck of a body.
568 /// It contains a tuple of all the types that could end up on a generator frame.
569 /// The state transformation MIR pass may only produce layouts which mention types
570 /// in this tuple. Upvars are not counted here.
571 pub fn witness(self) -> Ty<'tcx> {
572 self.split().witness.expect_ty()
575 /// Returns an iterator over the list of types of captured paths by the generator.
576 /// In case there was a type error in figuring out the types of the captured path, an
577 /// empty iterator is returned.
579 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
580 match self.tupled_upvars_ty().kind() {
581 TyKind::Error(_) => None,
582 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
583 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
584 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
590 /// Returns the tuple type representing the upvars for this generator.
592 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
593 self.split().tupled_upvars_ty.expect_ty()
596 /// Returns the type representing the resume type of the generator.
597 pub fn resume_ty(self) -> Ty<'tcx> {
598 self.split().resume_ty.expect_ty()
601 /// Returns the type representing the yield type of the generator.
602 pub fn yield_ty(self) -> Ty<'tcx> {
603 self.split().yield_ty.expect_ty()
606 /// Returns the type representing the return type of the generator.
607 pub fn return_ty(self) -> Ty<'tcx> {
608 self.split().return_ty.expect_ty()
611 /// Returns the "generator signature", which consists of its yield
612 /// and return types.
614 /// N.B., some bits of the code prefers to see this wrapped in a
615 /// binder, but it never contains bound regions. Probably this
616 /// function should be removed.
617 pub fn poly_sig(self) -> PolyGenSig<'tcx> {
618 ty::Binder::dummy(self.sig())
621 /// Returns the "generator signature", which consists of its resume, yield
622 /// and return types.
623 pub fn sig(self) -> GenSig<'tcx> {
625 resume_ty: self.resume_ty(),
626 yield_ty: self.yield_ty(),
627 return_ty: self.return_ty(),
632 impl<'tcx> GeneratorSubsts<'tcx> {
633 /// Generator has not been resumed yet.
634 pub const UNRESUMED: usize = 0;
635 /// Generator has returned or is completed.
636 pub const RETURNED: usize = 1;
637 /// Generator has been poisoned.
638 pub const POISONED: usize = 2;
640 const UNRESUMED_NAME: &'static str = "Unresumed";
641 const RETURNED_NAME: &'static str = "Returned";
642 const POISONED_NAME: &'static str = "Panicked";
644 /// The valid variant indices of this generator.
646 pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
647 // FIXME requires optimized MIR
648 let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
649 VariantIdx::new(0)..VariantIdx::new(num_variants)
652 /// The discriminant for the given variant. Panics if the `variant_index` is
655 pub fn discriminant_for_variant(
659 variant_index: VariantIdx,
661 // Generators don't support explicit discriminant values, so they are
662 // the same as the variant index.
663 assert!(self.variant_range(def_id, tcx).contains(&variant_index));
664 Discr { val: variant_index.as_usize() as u128, ty: self.discr_ty(tcx) }
667 /// The set of all discriminants for the generator, enumerated with their
670 pub fn discriminants(
674 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
675 self.variant_range(def_id, tcx).map(move |index| {
676 (index, Discr { val: index.as_usize() as u128, ty: self.discr_ty(tcx) })
680 /// Calls `f` with a reference to the name of the enumerator for the given
682 pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
684 Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
685 Self::RETURNED => Cow::from(Self::RETURNED_NAME),
686 Self::POISONED => Cow::from(Self::POISONED_NAME),
687 _ => Cow::from(format!("Suspend{}", v.as_usize() - 3)),
691 /// The type of the state discriminant used in the generator type.
693 pub fn discr_ty(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
697 /// This returns the types of the MIR locals which had to be stored across suspension points.
698 /// It is calculated in rustc_const_eval::transform::generator::StateTransform.
699 /// All the types here must be in the tuple in GeneratorInterior.
701 /// The locals are grouped by their variant number. Note that some locals may
702 /// be repeated in multiple variants.
708 ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
709 let layout = tcx.generator_layout(def_id).unwrap();
710 layout.variant_fields.iter().map(move |variant| {
711 variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs))
715 /// This is the types of the fields of a generator which are not stored in a
718 pub fn prefix_tys(self) -> impl Iterator<Item = Ty<'tcx>> {
723 #[derive(Debug, Copy, Clone, HashStable)]
724 pub enum UpvarSubsts<'tcx> {
725 Closure(SubstsRef<'tcx>),
726 Generator(SubstsRef<'tcx>),
729 impl<'tcx> UpvarSubsts<'tcx> {
730 /// Returns an iterator over the list of types of captured paths by the closure/generator.
731 /// In case there was a type error in figuring out the types of the captured path, an
732 /// empty iterator is returned.
734 pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
735 let tupled_tys = match self {
736 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
737 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
740 match tupled_tys.kind() {
741 TyKind::Error(_) => None,
742 TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
743 TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
744 ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
751 pub fn tupled_upvars_ty(self) -> Ty<'tcx> {
753 UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
754 UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
759 /// An inline const is modeled like
761 /// const InlineConst<'l0...'li, T0...Tj, R>: R;
765 /// - 'l0...'li and T0...Tj are the generic parameters
766 /// inherited from the item that defined the inline const,
767 /// - R represents the type of the constant.
769 /// When the inline const is instantiated, `R` is substituted as the actual inferred
770 /// type of the constant. The reason that `R` is represented as an extra type parameter
771 /// is the same reason that [`ClosureSubsts`] have `CS` and `U` as type parameters:
772 /// inline const can reference lifetimes that are internal to the creating function.
773 #[derive(Copy, Clone, Debug, TypeFoldable)]
774 pub struct InlineConstSubsts<'tcx> {
775 /// Generic parameters from the enclosing item,
776 /// concatenated with the inferred type of the constant.
777 pub substs: SubstsRef<'tcx>,
780 /// Struct returned by `split()`.
781 pub struct InlineConstSubstsParts<'tcx, T> {
782 pub parent_substs: &'tcx [GenericArg<'tcx>],
786 impl<'tcx> InlineConstSubsts<'tcx> {
787 /// Construct `InlineConstSubsts` from `InlineConstSubstsParts`.
790 parts: InlineConstSubstsParts<'tcx, Ty<'tcx>>,
791 ) -> InlineConstSubsts<'tcx> {
793 substs: tcx.mk_substs(
794 parts.parent_substs.iter().copied().chain(std::iter::once(parts.ty.into())),
799 /// Divides the inline const substs into their respective components.
800 /// The ordering assumed here must match that used by `InlineConstSubsts::new` above.
801 fn split(self) -> InlineConstSubstsParts<'tcx, GenericArg<'tcx>> {
802 match self.substs[..] {
803 [ref parent_substs @ .., ty] => InlineConstSubstsParts { parent_substs, ty },
804 _ => bug!("inline const substs missing synthetics"),
808 /// Returns the substitutions of the inline const's parent.
809 pub fn parent_substs(self) -> &'tcx [GenericArg<'tcx>] {
810 self.split().parent_substs
813 /// Returns the type of this inline const.
814 pub fn ty(self) -> Ty<'tcx> {
815 self.split().ty.expect_ty()
819 #[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash, TyEncodable, TyDecodable)]
820 #[derive(HashStable, TypeFoldable)]
821 pub enum ExistentialPredicate<'tcx> {
822 /// E.g., `Iterator`.
823 Trait(ExistentialTraitRef<'tcx>),
824 /// E.g., `Iterator::Item = T`.
825 Projection(ExistentialProjection<'tcx>),
830 impl<'tcx> ExistentialPredicate<'tcx> {
831 /// Compares via an ordering that will not change if modules are reordered or other changes are
832 /// made to the tree. In particular, this ordering is preserved across incremental compilations.
833 pub fn stable_cmp(&self, tcx: TyCtxt<'tcx>, other: &Self) -> Ordering {
834 use self::ExistentialPredicate::*;
835 match (*self, *other) {
836 (Trait(_), Trait(_)) => Ordering::Equal,
837 (Projection(ref a), Projection(ref b)) => {
838 tcx.def_path_hash(a.item_def_id).cmp(&tcx.def_path_hash(b.item_def_id))
840 (AutoTrait(ref a), AutoTrait(ref b)) => {
841 tcx.def_path_hash(*a).cmp(&tcx.def_path_hash(*b))
843 (Trait(_), _) => Ordering::Less,
844 (Projection(_), Trait(_)) => Ordering::Greater,
845 (Projection(_), _) => Ordering::Less,
846 (AutoTrait(_), _) => Ordering::Greater,
851 impl<'tcx> Binder<'tcx, ExistentialPredicate<'tcx>> {
852 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::Predicate<'tcx> {
853 use crate::ty::ToPredicate;
854 match self.skip_binder() {
855 ExistentialPredicate::Trait(tr) => {
856 self.rebind(tr).with_self_ty(tcx, self_ty).without_const().to_predicate(tcx)
858 ExistentialPredicate::Projection(p) => {
859 self.rebind(p.with_self_ty(tcx, self_ty)).to_predicate(tcx)
861 ExistentialPredicate::AutoTrait(did) => {
862 let trait_ref = self.rebind(ty::TraitRef {
864 substs: tcx.mk_substs_trait(self_ty, &[]),
866 trait_ref.without_const().to_predicate(tcx)
872 impl<'tcx> List<ty::Binder<'tcx, ExistentialPredicate<'tcx>>> {
873 /// Returns the "principal `DefId`" of this set of existential predicates.
875 /// A Rust trait object type consists (in addition to a lifetime bound)
876 /// of a set of trait bounds, which are separated into any number
877 /// of auto-trait bounds, and at most one non-auto-trait bound. The
878 /// non-auto-trait bound is called the "principal" of the trait
881 /// Only the principal can have methods or type parameters (because
882 /// auto traits can have neither of them). This is important, because
883 /// it means the auto traits can be treated as an unordered set (methods
884 /// would force an order for the vtable, while relating traits with
885 /// type parameters without knowing the order to relate them in is
886 /// a rather non-trivial task).
888 /// For example, in the trait object `dyn fmt::Debug + Sync`, the
889 /// principal bound is `Some(fmt::Debug)`, while the auto-trait bounds
890 /// are the set `{Sync}`.
892 /// It is also possible to have a "trivial" trait object that
893 /// consists only of auto traits, with no principal - for example,
894 /// `dyn Send + Sync`. In that case, the set of auto-trait bounds
895 /// is `{Send, Sync}`, while there is no principal. These trait objects
896 /// have a "trivial" vtable consisting of just the size, alignment,
898 pub fn principal(&self) -> Option<ty::Binder<'tcx, ExistentialTraitRef<'tcx>>> {
900 .map_bound(|this| match this {
901 ExistentialPredicate::Trait(tr) => Some(tr),
907 pub fn principal_def_id(&self) -> Option<DefId> {
908 self.principal().map(|trait_ref| trait_ref.skip_binder().def_id)
912 pub fn projection_bounds<'a>(
914 ) -> impl Iterator<Item = ty::Binder<'tcx, ExistentialProjection<'tcx>>> + 'a {
915 self.iter().filter_map(|predicate| {
917 .map_bound(|pred| match pred {
918 ExistentialPredicate::Projection(projection) => Some(projection),
926 pub fn auto_traits<'a>(&'a self) -> impl Iterator<Item = DefId> + 'a {
927 self.iter().filter_map(|predicate| match predicate.skip_binder() {
928 ExistentialPredicate::AutoTrait(did) => Some(did),
934 /// A complete reference to a trait. These take numerous guises in syntax,
935 /// but perhaps the most recognizable form is in a where-clause:
939 /// This would be represented by a trait-reference where the `DefId` is the
940 /// `DefId` for the trait `Foo` and the substs define `T` as parameter 0,
941 /// and `U` as parameter 1.
943 /// Trait references also appear in object types like `Foo<U>`, but in
944 /// that case the `Self` parameter is absent from the substitutions.
945 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
946 #[derive(HashStable, TypeFoldable)]
947 pub struct TraitRef<'tcx> {
949 pub substs: SubstsRef<'tcx>,
952 impl<'tcx> TraitRef<'tcx> {
953 pub fn new(def_id: DefId, substs: SubstsRef<'tcx>) -> TraitRef<'tcx> {
954 TraitRef { def_id, substs }
957 /// Returns a `TraitRef` of the form `P0: Foo<P1..Pn>` where `Pi`
958 /// are the parameters defined on trait.
959 pub fn identity(tcx: TyCtxt<'tcx>, def_id: DefId) -> Binder<'tcx, TraitRef<'tcx>> {
960 ty::Binder::dummy(TraitRef {
962 substs: InternalSubsts::identity_for_item(tcx, def_id),
967 pub fn self_ty(&self) -> Ty<'tcx> {
968 self.substs.type_at(0)
974 substs: SubstsRef<'tcx>,
975 ) -> ty::TraitRef<'tcx> {
976 let defs = tcx.generics_of(trait_id);
978 ty::TraitRef { def_id: trait_id, substs: tcx.intern_substs(&substs[..defs.params.len()]) }
982 pub type PolyTraitRef<'tcx> = Binder<'tcx, TraitRef<'tcx>>;
984 impl<'tcx> PolyTraitRef<'tcx> {
985 pub fn self_ty(&self) -> Binder<'tcx, Ty<'tcx>> {
986 self.map_bound_ref(|tr| tr.self_ty())
989 pub fn def_id(&self) -> DefId {
990 self.skip_binder().def_id
993 pub fn to_poly_trait_predicate(&self) -> ty::PolyTraitPredicate<'tcx> {
994 self.map_bound(|trait_ref| ty::TraitPredicate {
996 constness: ty::BoundConstness::NotConst,
997 polarity: ty::ImplPolarity::Positive,
1002 /// An existential reference to a trait, where `Self` is erased.
1003 /// For example, the trait object `Trait<'a, 'b, X, Y>` is:
1005 /// exists T. T: Trait<'a, 'b, X, Y>
1007 /// The substitutions don't include the erased `Self`, only trait
1008 /// type and lifetime parameters (`[X, Y]` and `['a, 'b]` above).
1009 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1010 #[derive(HashStable, TypeFoldable)]
1011 pub struct ExistentialTraitRef<'tcx> {
1013 pub substs: SubstsRef<'tcx>,
1016 impl<'tcx> ExistentialTraitRef<'tcx> {
1017 pub fn erase_self_ty(
1019 trait_ref: ty::TraitRef<'tcx>,
1020 ) -> ty::ExistentialTraitRef<'tcx> {
1021 // Assert there is a Self.
1022 trait_ref.substs.type_at(0);
1024 ty::ExistentialTraitRef {
1025 def_id: trait_ref.def_id,
1026 substs: tcx.intern_substs(&trait_ref.substs[1..]),
1030 /// Object types don't have a self type specified. Therefore, when
1031 /// we convert the principal trait-ref into a normal trait-ref,
1032 /// you must give *some* self type. A common choice is `mk_err()`
1033 /// or some placeholder type.
1034 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::TraitRef<'tcx> {
1035 // otherwise the escaping vars would be captured by the binder
1036 // debug_assert!(!self_ty.has_escaping_bound_vars());
1038 ty::TraitRef { def_id: self.def_id, substs: tcx.mk_substs_trait(self_ty, self.substs) }
1042 pub type PolyExistentialTraitRef<'tcx> = Binder<'tcx, ExistentialTraitRef<'tcx>>;
1044 impl<'tcx> PolyExistentialTraitRef<'tcx> {
1045 pub fn def_id(&self) -> DefId {
1046 self.skip_binder().def_id
1049 /// Object types don't have a self type specified. Therefore, when
1050 /// we convert the principal trait-ref into a normal trait-ref,
1051 /// you must give *some* self type. A common choice is `mk_err()`
1052 /// or some placeholder type.
1053 pub fn with_self_ty(&self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ty::PolyTraitRef<'tcx> {
1054 self.map_bound(|trait_ref| trait_ref.with_self_ty(tcx, self_ty))
1058 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1059 #[derive(HashStable)]
1060 pub enum BoundVariableKind {
1062 Region(BoundRegionKind),
1066 /// Binder is a binder for higher-ranked lifetimes or types. It is part of the
1067 /// compiler's representation for things like `for<'a> Fn(&'a isize)`
1068 /// (which would be represented by the type `PolyTraitRef ==
1069 /// Binder<'tcx, TraitRef>`). Note that when we instantiate,
1070 /// erase, or otherwise "discharge" these bound vars, we change the
1071 /// type from `Binder<'tcx, T>` to just `T` (see
1072 /// e.g., `liberate_late_bound_regions`).
1074 /// `Decodable` and `Encodable` are implemented for `Binder<T>` using the `impl_binder_encode_decode!` macro.
1075 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
1076 pub struct Binder<'tcx, T>(T, &'tcx List<BoundVariableKind>);
1078 impl<'tcx, T> Binder<'tcx, T>
1080 T: TypeFoldable<'tcx>,
1082 /// Wraps `value` in a binder, asserting that `value` does not
1083 /// contain any bound vars that would be bound by the
1084 /// binder. This is commonly used to 'inject' a value T into a
1085 /// different binding level.
1086 pub fn dummy(value: T) -> Binder<'tcx, T> {
1087 assert!(!value.has_escaping_bound_vars());
1088 Binder(value, ty::List::empty())
1091 pub fn bind_with_vars(value: T, vars: &'tcx List<BoundVariableKind>) -> Binder<'tcx, T> {
1092 if cfg!(debug_assertions) {
1093 let mut validator = ValidateBoundVars::new(vars);
1094 value.visit_with(&mut validator);
1100 impl<'tcx, T> Binder<'tcx, T> {
1101 /// Skips the binder and returns the "bound" value. This is a
1102 /// risky thing to do because it's easy to get confused about
1103 /// De Bruijn indices and the like. It is usually better to
1104 /// discharge the binder using `no_bound_vars` or
1105 /// `replace_late_bound_regions` or something like
1106 /// that. `skip_binder` is only valid when you are either
1107 /// extracting data that has nothing to do with bound vars, you
1108 /// are doing some sort of test that does not involve bound
1109 /// regions, or you are being very careful about your depth
1112 /// Some examples where `skip_binder` is reasonable:
1114 /// - extracting the `DefId` from a PolyTraitRef;
1115 /// - comparing the self type of a PolyTraitRef to see if it is equal to
1116 /// a type parameter `X`, since the type `X` does not reference any regions
1117 pub fn skip_binder(self) -> T {
1121 pub fn bound_vars(&self) -> &'tcx List<BoundVariableKind> {
1125 pub fn as_ref(&self) -> Binder<'tcx, &T> {
1126 Binder(&self.0, self.1)
1129 pub fn map_bound_ref_unchecked<F, U>(&self, f: F) -> Binder<'tcx, U>
1133 let value = f(&self.0);
1134 Binder(value, self.1)
1137 pub fn map_bound_ref<F, U: TypeFoldable<'tcx>>(&self, f: F) -> Binder<'tcx, U>
1141 self.as_ref().map_bound(f)
1144 pub fn map_bound<F, U: TypeFoldable<'tcx>>(self, f: F) -> Binder<'tcx, U>
1148 let value = f(self.0);
1149 if cfg!(debug_assertions) {
1150 let mut validator = ValidateBoundVars::new(self.1);
1151 value.visit_with(&mut validator);
1153 Binder(value, self.1)
1156 pub fn try_map_bound<F, U: TypeFoldable<'tcx>, E>(self, f: F) -> Result<Binder<'tcx, U>, E>
1158 F: FnOnce(T) -> Result<U, E>,
1160 let value = f(self.0)?;
1161 if cfg!(debug_assertions) {
1162 let mut validator = ValidateBoundVars::new(self.1);
1163 value.visit_with(&mut validator);
1165 Ok(Binder(value, self.1))
1168 /// Wraps a `value` in a binder, using the same bound variables as the
1169 /// current `Binder`. This should not be used if the new value *changes*
1170 /// the bound variables. Note: the (old or new) value itself does not
1171 /// necessarily need to *name* all the bound variables.
1173 /// This currently doesn't do anything different than `bind`, because we
1174 /// don't actually track bound vars. However, semantically, it is different
1175 /// because bound vars aren't allowed to change here, whereas they are
1176 /// in `bind`. This may be (debug) asserted in the future.
1177 pub fn rebind<U>(&self, value: U) -> Binder<'tcx, U>
1179 U: TypeFoldable<'tcx>,
1181 if cfg!(debug_assertions) {
1182 let mut validator = ValidateBoundVars::new(self.bound_vars());
1183 value.visit_with(&mut validator);
1185 Binder(value, self.1)
1188 /// Unwraps and returns the value within, but only if it contains
1189 /// no bound vars at all. (In other words, if this binder --
1190 /// and indeed any enclosing binder -- doesn't bind anything at
1191 /// all.) Otherwise, returns `None`.
1193 /// (One could imagine having a method that just unwraps a single
1194 /// binder, but permits late-bound vars bound by enclosing
1195 /// binders, but that would require adjusting the debruijn
1196 /// indices, and given the shallow binding structure we often use,
1197 /// would not be that useful.)
1198 pub fn no_bound_vars(self) -> Option<T>
1200 T: TypeFoldable<'tcx>,
1202 if self.0.has_escaping_bound_vars() { None } else { Some(self.skip_binder()) }
1205 /// Splits the contents into two things that share the same binder
1206 /// level as the original, returning two distinct binders.
1208 /// `f` should consider bound regions at depth 1 to be free, and
1209 /// anything it produces with bound regions at depth 1 will be
1210 /// bound in the resulting return values.
1211 pub fn split<U, V, F>(self, f: F) -> (Binder<'tcx, U>, Binder<'tcx, V>)
1213 F: FnOnce(T) -> (U, V),
1215 let (u, v) = f(self.0);
1216 (Binder(u, self.1), Binder(v, self.1))
1220 impl<'tcx, T> Binder<'tcx, Option<T>> {
1221 pub fn transpose(self) -> Option<Binder<'tcx, T>> {
1222 let bound_vars = self.1;
1223 self.0.map(|v| Binder(v, bound_vars))
1227 /// Represents the projection of an associated type. In explicit UFCS
1228 /// form this would be written `<T as Trait<..>>::N`.
1229 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1230 #[derive(HashStable, TypeFoldable)]
1231 pub struct ProjectionTy<'tcx> {
1232 /// The parameters of the associated item.
1233 pub substs: SubstsRef<'tcx>,
1235 /// The `DefId` of the `TraitItem` for the associated type `N`.
1237 /// Note that this is not the `DefId` of the `TraitRef` containing this
1238 /// associated type, which is in `tcx.associated_item(item_def_id).container`.
1239 pub item_def_id: DefId,
1242 impl<'tcx> ProjectionTy<'tcx> {
1243 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1244 tcx.associated_item(self.item_def_id).container.id()
1247 /// Extracts the underlying trait reference and own substs from this projection.
1248 /// For example, if this is a projection of `<T as StreamingIterator>::Item<'a>`,
1249 /// then this function would return a `T: Iterator` trait reference and `['a]` as the own substs
1250 pub fn trait_ref_and_own_substs(
1253 ) -> (ty::TraitRef<'tcx>, &'tcx [ty::GenericArg<'tcx>]) {
1254 let def_id = tcx.associated_item(self.item_def_id).container.id();
1255 let trait_generics = tcx.generics_of(def_id);
1257 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, trait_generics) },
1258 &self.substs[trait_generics.count()..],
1262 /// Extracts the underlying trait reference from this projection.
1263 /// For example, if this is a projection of `<T as Iterator>::Item`,
1264 /// then this function would return a `T: Iterator` trait reference.
1266 /// WARNING: This will drop the substs for generic associated types
1267 /// consider calling [Self::trait_ref_and_own_substs] to get those
1269 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::TraitRef<'tcx> {
1270 let def_id = self.trait_def_id(tcx);
1271 ty::TraitRef { def_id, substs: self.substs.truncate_to(tcx, tcx.generics_of(def_id)) }
1274 pub fn self_ty(&self) -> Ty<'tcx> {
1275 self.substs.type_at(0)
1279 #[derive(Copy, Clone, Debug, TypeFoldable)]
1280 pub struct GenSig<'tcx> {
1281 pub resume_ty: Ty<'tcx>,
1282 pub yield_ty: Ty<'tcx>,
1283 pub return_ty: Ty<'tcx>,
1286 pub type PolyGenSig<'tcx> = Binder<'tcx, GenSig<'tcx>>;
1288 /// Signature of a function type, which we have arbitrarily
1289 /// decided to use to refer to the input/output types.
1291 /// - `inputs`: is the list of arguments and their modes.
1292 /// - `output`: is the return type.
1293 /// - `c_variadic`: indicates whether this is a C-variadic function.
1294 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1295 #[derive(HashStable, TypeFoldable)]
1296 pub struct FnSig<'tcx> {
1297 pub inputs_and_output: &'tcx List<Ty<'tcx>>,
1298 pub c_variadic: bool,
1299 pub unsafety: hir::Unsafety,
1303 impl<'tcx> FnSig<'tcx> {
1304 pub fn inputs(&self) -> &'tcx [Ty<'tcx>] {
1305 &self.inputs_and_output[..self.inputs_and_output.len() - 1]
1308 pub fn output(&self) -> Ty<'tcx> {
1309 self.inputs_and_output[self.inputs_and_output.len() - 1]
1312 // Creates a minimal `FnSig` to be used when encountering a `TyKind::Error` in a fallible
1314 fn fake() -> FnSig<'tcx> {
1316 inputs_and_output: List::empty(),
1318 unsafety: hir::Unsafety::Normal,
1319 abi: abi::Abi::Rust,
1324 pub type PolyFnSig<'tcx> = Binder<'tcx, FnSig<'tcx>>;
1326 impl<'tcx> PolyFnSig<'tcx> {
1328 pub fn inputs(&self) -> Binder<'tcx, &'tcx [Ty<'tcx>]> {
1329 self.map_bound_ref_unchecked(|fn_sig| fn_sig.inputs())
1332 pub fn input(&self, index: usize) -> ty::Binder<'tcx, Ty<'tcx>> {
1333 self.map_bound_ref(|fn_sig| fn_sig.inputs()[index])
1335 pub fn inputs_and_output(&self) -> ty::Binder<'tcx, &'tcx List<Ty<'tcx>>> {
1336 self.map_bound_ref(|fn_sig| fn_sig.inputs_and_output)
1339 pub fn output(&self) -> ty::Binder<'tcx, Ty<'tcx>> {
1340 self.map_bound_ref(|fn_sig| fn_sig.output())
1342 pub fn c_variadic(&self) -> bool {
1343 self.skip_binder().c_variadic
1345 pub fn unsafety(&self) -> hir::Unsafety {
1346 self.skip_binder().unsafety
1348 pub fn abi(&self) -> abi::Abi {
1349 self.skip_binder().abi
1353 pub type CanonicalPolyFnSig<'tcx> = Canonical<'tcx, Binder<'tcx, FnSig<'tcx>>>;
1355 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1356 #[derive(HashStable)]
1357 pub struct ParamTy {
1362 impl<'tcx> ParamTy {
1363 pub fn new(index: u32, name: Symbol) -> ParamTy {
1364 ParamTy { index, name }
1367 pub fn for_def(def: &ty::GenericParamDef) -> ParamTy {
1368 ParamTy::new(def.index, def.name)
1372 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1373 tcx.mk_ty_param(self.index, self.name)
1377 #[derive(Copy, Clone, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
1378 #[derive(HashStable)]
1379 pub struct ParamConst {
1385 pub fn new(index: u32, name: Symbol) -> ParamConst {
1386 ParamConst { index, name }
1389 pub fn for_def(def: &ty::GenericParamDef) -> ParamConst {
1390 ParamConst::new(def.index, def.name)
1394 pub type Region<'tcx> = &'tcx RegionKind;
1396 /// Representation of regions. Note that the NLL checker uses a distinct
1397 /// representation of regions. For this reason, it internally replaces all the
1398 /// regions with inference variables -- the index of the variable is then used
1399 /// to index into internal NLL data structures. See `rustc_const_eval::borrow_check`
1400 /// module for more information.
1402 /// ## The Region lattice within a given function
1404 /// In general, the region lattice looks like
1407 /// static ----------+-----...------+ (greatest)
1409 /// early-bound and | |
1410 /// free regions | |
1413 /// empty(root) placeholder(U1) |
1415 /// | / placeholder(Un)
1420 /// empty(Un) -------- (smallest)
1423 /// Early-bound/free regions are the named lifetimes in scope from the
1424 /// function declaration. They have relationships to one another
1425 /// determined based on the declared relationships from the
1428 /// Note that inference variables and bound regions are not included
1429 /// in this diagram. In the case of inference variables, they should
1430 /// be inferred to some other region from the diagram. In the case of
1431 /// bound regions, they are excluded because they don't make sense to
1432 /// include -- the diagram indicates the relationship between free
1435 /// ## Inference variables
1437 /// During region inference, we sometimes create inference variables,
1438 /// represented as `ReVar`. These will be inferred by the code in
1439 /// `infer::lexical_region_resolve` to some free region from the
1440 /// lattice above (the minimal region that meets the
1443 /// During NLL checking, where regions are defined differently, we
1444 /// also use `ReVar` -- in that case, the index is used to index into
1445 /// the NLL region checker's data structures. The variable may in fact
1446 /// represent either a free region or an inference variable, in that
1449 /// ## Bound Regions
1451 /// These are regions that are stored behind a binder and must be substituted
1452 /// with some concrete region before being used. There are two kind of
1453 /// bound regions: early-bound, which are bound in an item's `Generics`,
1454 /// and are substituted by an `InternalSubsts`, and late-bound, which are part of
1455 /// higher-ranked types (e.g., `for<'a> fn(&'a ())`), and are substituted by
1456 /// the likes of `liberate_late_bound_regions`. The distinction exists
1457 /// because higher-ranked lifetimes aren't supported in all places. See [1][2].
1459 /// Unlike `Param`s, bound regions are not supposed to exist "in the wild"
1460 /// outside their binder, e.g., in types passed to type inference, and
1461 /// should first be substituted (by placeholder regions, free regions,
1462 /// or region variables).
1464 /// ## Placeholder and Free Regions
1466 /// One often wants to work with bound regions without knowing their precise
1467 /// identity. For example, when checking a function, the lifetime of a borrow
1468 /// can end up being assigned to some region parameter. In these cases,
1469 /// it must be ensured that bounds on the region can't be accidentally
1470 /// assumed without being checked.
1472 /// To do this, we replace the bound regions with placeholder markers,
1473 /// which don't satisfy any relation not explicitly provided.
1475 /// There are two kinds of placeholder regions in rustc: `ReFree` and
1476 /// `RePlaceholder`. When checking an item's body, `ReFree` is supposed
1477 /// to be used. These also support explicit bounds: both the internally-stored
1478 /// *scope*, which the region is assumed to outlive, as well as other
1479 /// relations stored in the `FreeRegionMap`. Note that these relations
1480 /// aren't checked when you `make_subregion` (or `eq_types`), only by
1481 /// `resolve_regions_and_report_errors`.
1483 /// When working with higher-ranked types, some region relations aren't
1484 /// yet known, so you can't just call `resolve_regions_and_report_errors`.
1485 /// `RePlaceholder` is designed for this purpose. In these contexts,
1486 /// there's also the risk that some inference variable laying around will
1487 /// get unified with your placeholder region: if you want to check whether
1488 /// `for<'a> Foo<'_>: 'a`, and you substitute your bound region `'a`
1489 /// with a placeholder region `'%a`, the variable `'_` would just be
1490 /// instantiated to the placeholder region `'%a`, which is wrong because
1491 /// the inference variable is supposed to satisfy the relation
1492 /// *for every value of the placeholder region*. To ensure that doesn't
1493 /// happen, you can use `leak_check`. This is more clearly explained
1494 /// by the [rustc dev guide].
1496 /// [1]: https://smallcultfollowing.com/babysteps/blog/2013/10/29/intermingled-parameter-lists/
1497 /// [2]: https://smallcultfollowing.com/babysteps/blog/2013/11/04/intermingled-parameter-lists/
1498 /// [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
1499 #[derive(Clone, PartialEq, Eq, Hash, Copy, TyEncodable, TyDecodable, PartialOrd, Ord)]
1500 pub enum RegionKind {
1501 /// Region bound in a type or fn declaration which will be
1502 /// substituted 'early' -- that is, at the same time when type
1503 /// parameters are substituted.
1504 ReEarlyBound(EarlyBoundRegion),
1506 /// Region bound in a function scope, which will be substituted when the
1507 /// function is called.
1508 ReLateBound(ty::DebruijnIndex, BoundRegion),
1510 /// When checking a function body, the types of all arguments and so forth
1511 /// that refer to bound region parameters are modified to refer to free
1512 /// region parameters.
1515 /// Static data that has an "infinite" lifetime. Top in the region lattice.
1518 /// A region variable. Should not exist outside of type inference.
1521 /// A placeholder region -- basically, the higher-ranked version of `ReFree`.
1522 /// Should not exist outside of type inference.
1523 RePlaceholder(ty::PlaceholderRegion),
1525 /// Empty lifetime is for data that is never accessed. We tag the
1526 /// empty lifetime with a universe -- the idea is that we don't
1527 /// want `exists<'a> { forall<'b> { 'b: 'a } }` to be satisfiable.
1528 /// Therefore, the `'empty` in a universe `U` is less than all
1529 /// regions visible from `U`, but not less than regions not visible
1531 ReEmpty(ty::UniverseIndex),
1533 /// Erased region, used by trait selection, in MIR and during codegen.
1537 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, PartialOrd, Ord)]
1538 pub struct EarlyBoundRegion {
1544 /// A **`const`** **v**ariable **ID**.
1545 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
1546 pub struct ConstVid<'tcx> {
1548 pub phantom: PhantomData<&'tcx ()>,
1551 rustc_index::newtype_index! {
1552 /// A **region** (lifetime) **v**ariable **ID**.
1553 pub struct RegionVid {
1554 DEBUG_FORMAT = custom,
1558 impl Atom for RegionVid {
1559 fn index(self) -> usize {
1564 rustc_index::newtype_index! {
1565 pub struct BoundVar { .. }
1568 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1569 #[derive(HashStable)]
1570 pub struct BoundTy {
1572 pub kind: BoundTyKind,
1575 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1576 #[derive(HashStable)]
1577 pub enum BoundTyKind {
1582 impl From<BoundVar> for BoundTy {
1583 fn from(var: BoundVar) -> Self {
1584 BoundTy { var, kind: BoundTyKind::Anon }
1588 /// A `ProjectionPredicate` for an `ExistentialTraitRef`.
1589 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1590 #[derive(HashStable, TypeFoldable)]
1591 pub struct ExistentialProjection<'tcx> {
1592 pub item_def_id: DefId,
1593 pub substs: SubstsRef<'tcx>,
1594 pub term: Term<'tcx>,
1597 pub type PolyExistentialProjection<'tcx> = Binder<'tcx, ExistentialProjection<'tcx>>;
1599 impl<'tcx> ExistentialProjection<'tcx> {
1600 /// Extracts the underlying existential trait reference from this projection.
1601 /// For example, if this is a projection of `exists T. <T as Iterator>::Item == X`,
1602 /// then this function would return an `exists T. T: Iterator` existential trait
1604 pub fn trait_ref(&self, tcx: TyCtxt<'tcx>) -> ty::ExistentialTraitRef<'tcx> {
1605 let def_id = tcx.associated_item(self.item_def_id).container.id();
1606 let subst_count = tcx.generics_of(def_id).count() - 1;
1607 let substs = tcx.intern_substs(&self.substs[..subst_count]);
1608 ty::ExistentialTraitRef { def_id, substs }
1611 pub fn with_self_ty(
1615 ) -> ty::ProjectionPredicate<'tcx> {
1616 // otherwise the escaping regions would be captured by the binders
1617 debug_assert!(!self_ty.has_escaping_bound_vars());
1619 ty::ProjectionPredicate {
1620 projection_ty: ty::ProjectionTy {
1621 item_def_id: self.item_def_id,
1622 substs: tcx.mk_substs_trait(self_ty, self.substs),
1628 pub fn erase_self_ty(
1630 projection_predicate: ty::ProjectionPredicate<'tcx>,
1632 // Assert there is a Self.
1633 projection_predicate.projection_ty.substs.type_at(0);
1636 item_def_id: projection_predicate.projection_ty.item_def_id,
1637 substs: tcx.intern_substs(&projection_predicate.projection_ty.substs[1..]),
1638 term: projection_predicate.term,
1643 impl<'tcx> PolyExistentialProjection<'tcx> {
1644 pub fn with_self_ty(
1648 ) -> ty::PolyProjectionPredicate<'tcx> {
1649 self.map_bound(|p| p.with_self_ty(tcx, self_ty))
1652 pub fn item_def_id(&self) -> DefId {
1653 self.skip_binder().item_def_id
1657 /// Region utilities
1659 /// Is this region named by the user?
1660 pub fn has_name(&self) -> bool {
1662 RegionKind::ReEarlyBound(ebr) => ebr.has_name(),
1663 RegionKind::ReLateBound(_, br) => br.kind.is_named(),
1664 RegionKind::ReFree(fr) => fr.bound_region.is_named(),
1665 RegionKind::ReStatic => true,
1666 RegionKind::ReVar(..) => false,
1667 RegionKind::RePlaceholder(placeholder) => placeholder.name.is_named(),
1668 RegionKind::ReEmpty(_) => false,
1669 RegionKind::ReErased => false,
1674 pub fn is_late_bound(&self) -> bool {
1675 matches!(*self, ty::ReLateBound(..))
1679 pub fn is_placeholder(&self) -> bool {
1680 matches!(*self, ty::RePlaceholder(..))
1684 pub fn bound_at_or_above_binder(&self, index: ty::DebruijnIndex) -> bool {
1686 ty::ReLateBound(debruijn, _) => debruijn >= index,
1691 pub fn type_flags(&self) -> TypeFlags {
1692 let mut flags = TypeFlags::empty();
1696 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1697 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1698 flags = flags | TypeFlags::HAS_RE_INFER;
1700 ty::RePlaceholder(..) => {
1701 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1702 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1703 flags = flags | TypeFlags::HAS_RE_PLACEHOLDER;
1705 ty::ReEarlyBound(..) => {
1706 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1707 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1708 flags = flags | TypeFlags::HAS_RE_PARAM;
1710 ty::ReFree { .. } => {
1711 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1712 flags = flags | TypeFlags::HAS_FREE_LOCAL_REGIONS;
1714 ty::ReEmpty(_) | ty::ReStatic => {
1715 flags = flags | TypeFlags::HAS_FREE_REGIONS;
1717 ty::ReLateBound(..) => {
1718 flags = flags | TypeFlags::HAS_RE_LATE_BOUND;
1721 flags = flags | TypeFlags::HAS_RE_ERASED;
1725 debug!("type_flags({:?}) = {:?}", self, flags);
1730 /// Given an early-bound or free region, returns the `DefId` where it was bound.
1731 /// For example, consider the regions in this snippet of code:
1735 /// ^^ -- early bound, declared on an impl
1737 /// fn bar<'b, 'c>(x: &self, y: &'b u32, z: &'c u64) where 'static: 'c
1738 /// ^^ ^^ ^ anonymous, late-bound
1739 /// | early-bound, appears in where-clauses
1740 /// late-bound, appears only in fn args
1745 /// Here, `free_region_binding_scope('a)` would return the `DefId`
1746 /// of the impl, and for all the other highlighted regions, it
1747 /// would return the `DefId` of the function. In other cases (not shown), this
1748 /// function might return the `DefId` of a closure.
1749 pub fn free_region_binding_scope(&self, tcx: TyCtxt<'_>) -> DefId {
1751 ty::ReEarlyBound(br) => tcx.parent(br.def_id).unwrap(),
1752 ty::ReFree(fr) => fr.scope,
1753 _ => bug!("free_region_binding_scope invoked on inappropriate region: {:?}", self),
1759 impl<'tcx> TyS<'tcx> {
1761 pub fn kind(&self) -> &TyKind<'tcx> {
1766 pub fn flags(&self) -> TypeFlags {
1771 pub fn is_unit(&self) -> bool {
1773 Tuple(ref tys) => tys.is_empty(),
1779 pub fn is_never(&self) -> bool {
1780 matches!(self.kind(), Never)
1784 pub fn is_primitive(&self) -> bool {
1785 self.kind().is_primitive()
1789 pub fn is_adt(&self) -> bool {
1790 matches!(self.kind(), Adt(..))
1794 pub fn is_ref(&self) -> bool {
1795 matches!(self.kind(), Ref(..))
1799 pub fn is_ty_var(&self) -> bool {
1800 matches!(self.kind(), Infer(TyVar(_)))
1804 pub fn ty_vid(&self) -> Option<ty::TyVid> {
1806 &Infer(TyVar(vid)) => Some(vid),
1812 pub fn is_ty_infer(&self) -> bool {
1813 matches!(self.kind(), Infer(_))
1817 pub fn is_phantom_data(&self) -> bool {
1818 if let Adt(def, _) = self.kind() { def.is_phantom_data() } else { false }
1822 pub fn is_bool(&self) -> bool {
1823 *self.kind() == Bool
1826 /// Returns `true` if this type is a `str`.
1828 pub fn is_str(&self) -> bool {
1833 pub fn is_param(&self, index: u32) -> bool {
1835 ty::Param(ref data) => data.index == index,
1841 pub fn is_slice(&self) -> bool {
1843 RawPtr(TypeAndMut { ty, .. }) | Ref(_, ty, _) => matches!(ty.kind(), Slice(_) | Str),
1849 pub fn is_array(&self) -> bool {
1850 matches!(self.kind(), Array(..))
1854 pub fn is_simd(&self) -> bool {
1856 Adt(def, _) => def.repr.simd(),
1861 pub fn sequence_element_type(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
1863 Array(ty, _) | Slice(ty) => ty,
1864 Str => tcx.types.u8,
1865 _ => bug!("`sequence_element_type` called on non-sequence value: {}", self),
1869 pub fn simd_size_and_type(&self, tcx: TyCtxt<'tcx>) -> (u64, Ty<'tcx>) {
1871 Adt(def, substs) => {
1872 assert!(def.repr.simd(), "`simd_size_and_type` called on non-SIMD type");
1873 let variant = def.non_enum_variant();
1874 let f0_ty = variant.fields[0].ty(tcx, substs);
1876 match f0_ty.kind() {
1877 // If the first field is an array, we assume it is the only field and its
1878 // elements are the SIMD components.
1879 Array(f0_elem_ty, f0_len) => {
1880 // FIXME(repr_simd): https://github.com/rust-lang/rust/pull/78863#discussion_r522784112
1881 // The way we evaluate the `N` in `[T; N]` here only works since we use
1882 // `simd_size_and_type` post-monomorphization. It will probably start to ICE
1883 // if we use it in generic code. See the `simd-array-trait` ui test.
1884 (f0_len.eval_usize(tcx, ParamEnv::empty()) as u64, f0_elem_ty)
1886 // Otherwise, the fields of this Adt are the SIMD components (and we assume they
1887 // all have the same type).
1888 _ => (variant.fields.len() as u64, f0_ty),
1891 _ => bug!("`simd_size_and_type` called on invalid type"),
1896 pub fn is_region_ptr(&self) -> bool {
1897 matches!(self.kind(), Ref(..))
1901 pub fn is_mutable_ptr(&self) -> bool {
1904 RawPtr(TypeAndMut { mutbl: hir::Mutability::Mut, .. })
1905 | Ref(_, _, hir::Mutability::Mut)
1909 /// Get the mutability of the reference or `None` when not a reference
1911 pub fn ref_mutability(&self) -> Option<hir::Mutability> {
1913 Ref(_, _, mutability) => Some(*mutability),
1919 pub fn is_unsafe_ptr(&self) -> bool {
1920 matches!(self.kind(), RawPtr(_))
1923 /// Tests if this is any kind of primitive pointer type (reference, raw pointer, fn pointer).
1925 pub fn is_any_ptr(&self) -> bool {
1926 self.is_region_ptr() || self.is_unsafe_ptr() || self.is_fn_ptr()
1930 pub fn is_box(&self) -> bool {
1932 Adt(def, _) => def.is_box(),
1937 /// Panics if called on any type other than `Box<T>`.
1938 pub fn boxed_ty(&self) -> Ty<'tcx> {
1940 Adt(def, substs) if def.is_box() => substs.type_at(0),
1941 _ => bug!("`boxed_ty` is called on non-box type {:?}", self),
1945 /// A scalar type is one that denotes an atomic datum, with no sub-components.
1946 /// (A RawPtr is scalar because it represents a non-managed pointer, so its
1947 /// contents are abstract to rustc.)
1949 pub fn is_scalar(&self) -> bool {
1959 | Infer(IntVar(_) | FloatVar(_))
1963 /// Returns `true` if this type is a floating point type.
1965 pub fn is_floating_point(&self) -> bool {
1966 matches!(self.kind(), Float(_) | Infer(FloatVar(_)))
1970 pub fn is_trait(&self) -> bool {
1971 matches!(self.kind(), Dynamic(..))
1975 pub fn is_enum(&self) -> bool {
1976 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_enum())
1980 pub fn is_union(&self) -> bool {
1981 matches!(self.kind(), Adt(adt_def, _) if adt_def.is_union())
1985 pub fn is_closure(&self) -> bool {
1986 matches!(self.kind(), Closure(..))
1990 pub fn is_generator(&self) -> bool {
1991 matches!(self.kind(), Generator(..))
1995 pub fn is_integral(&self) -> bool {
1996 matches!(self.kind(), Infer(IntVar(_)) | Int(_) | Uint(_))
2000 pub fn is_fresh_ty(&self) -> bool {
2001 matches!(self.kind(), Infer(FreshTy(_)))
2005 pub fn is_fresh(&self) -> bool {
2006 matches!(self.kind(), Infer(FreshTy(_) | FreshIntTy(_) | FreshFloatTy(_)))
2010 pub fn is_char(&self) -> bool {
2011 matches!(self.kind(), Char)
2015 pub fn is_numeric(&self) -> bool {
2016 self.is_integral() || self.is_floating_point()
2020 pub fn is_signed(&self) -> bool {
2021 matches!(self.kind(), Int(_))
2025 pub fn is_ptr_sized_integral(&self) -> bool {
2026 matches!(self.kind(), Int(ty::IntTy::Isize) | Uint(ty::UintTy::Usize))
2030 pub fn has_concrete_skeleton(&self) -> bool {
2031 !matches!(self.kind(), Param(_) | Infer(_) | Error(_))
2034 /// Returns the type and mutability of `*ty`.
2036 /// The parameter `explicit` indicates if this is an *explicit* dereference.
2037 /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
2038 pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut<'tcx>> {
2040 Adt(def, _) if def.is_box() => {
2041 Some(TypeAndMut { ty: self.boxed_ty(), mutbl: hir::Mutability::Not })
2043 Ref(_, ty, mutbl) => Some(TypeAndMut { ty, mutbl: *mutbl }),
2044 RawPtr(mt) if explicit => Some(*mt),
2049 /// Returns the type of `ty[i]`.
2050 pub fn builtin_index(&self) -> Option<Ty<'tcx>> {
2052 Array(ty, _) | Slice(ty) => Some(ty),
2057 pub fn fn_sig(&self, tcx: TyCtxt<'tcx>) -> PolyFnSig<'tcx> {
2059 FnDef(def_id, substs) => tcx.fn_sig(*def_id).subst(tcx, substs),
2062 // ignore errors (#54954)
2063 ty::Binder::dummy(FnSig::fake())
2065 Closure(..) => bug!(
2066 "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
2068 _ => bug!("Ty::fn_sig() called on non-fn type: {:?}", self),
2073 pub fn is_fn(&self) -> bool {
2074 matches!(self.kind(), FnDef(..) | FnPtr(_))
2078 pub fn is_fn_ptr(&self) -> bool {
2079 matches!(self.kind(), FnPtr(_))
2083 pub fn is_impl_trait(&self) -> bool {
2084 matches!(self.kind(), Opaque(..))
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 /// Get the `i`-th element of a tuple.
2105 /// Panics when called on anything but a tuple.
2106 pub fn tuple_element_ty(&self, i: usize) -> Option<Ty<'tcx>> {
2108 Tuple(substs) => substs.iter().nth(i).map(|field| field.expect_ty()),
2109 _ => bug!("tuple_fields called on non-tuple"),
2113 /// If the type contains variants, returns the valid range of variant indices.
2115 // FIXME: This requires the optimized MIR in the case of generators.
2117 pub fn variant_range(&self, tcx: TyCtxt<'tcx>) -> Option<Range<VariantIdx>> {
2119 TyKind::Adt(adt, _) => Some(adt.variant_range()),
2120 TyKind::Generator(def_id, substs, _) => {
2121 Some(substs.as_generator().variant_range(*def_id, tcx))
2127 /// If the type contains variants, returns the variant for `variant_index`.
2128 /// Panics if `variant_index` is out of range.
2130 // FIXME: This requires the optimized MIR in the case of generators.
2132 pub fn discriminant_for_variant(
2135 variant_index: VariantIdx,
2136 ) -> Option<Discr<'tcx>> {
2138 TyKind::Adt(adt, _) if adt.variants.is_empty() => {
2139 // This can actually happen during CTFE, see
2140 // https://github.com/rust-lang/rust/issues/89765.
2143 TyKind::Adt(adt, _) if adt.is_enum() => {
2144 Some(adt.discriminant_for_variant(tcx, variant_index))
2146 TyKind::Generator(def_id, substs, _) => {
2147 Some(substs.as_generator().discriminant_for_variant(*def_id, tcx, variant_index))
2153 /// Returns the type of the discriminant of this type.
2154 pub fn discriminant_ty(&'tcx self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2156 ty::Adt(adt, _) if adt.is_enum() => adt.repr.discr_type().to_ty(tcx),
2157 ty::Generator(_, substs, _) => substs.as_generator().discr_ty(tcx),
2159 ty::Param(_) | ty::Projection(_) | ty::Opaque(..) | ty::Infer(ty::TyVar(_)) => {
2160 let assoc_items = tcx.associated_item_def_ids(
2161 tcx.require_lang_item(hir::LangItem::DiscriminantKind, None),
2163 tcx.mk_projection(assoc_items[0], tcx.intern_substs(&[self.into()]))
2182 | ty::GeneratorWitness(..)
2186 | ty::Infer(IntVar(_) | FloatVar(_)) => tcx.types.u8,
2189 | ty::Placeholder(_)
2190 | ty::Infer(FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2191 bug!("`discriminant_ty` applied to unexpected type: {:?}", self)
2196 /// Returns the type of metadata for (potentially fat) pointers to this type.
2197 pub fn ptr_metadata_ty(
2200 normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
2202 let tail = tcx.struct_tail_with_normalize(self, normalize);
2205 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2216 | ty::GeneratorWitness(..)
2222 // If returned by `struct_tail_without_normalization` this is a unit struct
2223 // without any fields, or not a struct, and therefore is Sized.
2225 // If returned by `struct_tail_without_normalization` this is the empty tuple,
2226 // a.k.a. unit type, which is Sized
2227 | ty::Tuple(..) => tcx.types.unit,
2229 ty::Str | ty::Slice(_) => tcx.types.usize,
2230 ty::Dynamic(..) => {
2231 let dyn_metadata = tcx.lang_items().dyn_metadata().unwrap();
2232 tcx.type_of(dyn_metadata).subst(tcx, &[tail.into()])
2238 | ty::Infer(ty::TyVar(_))
2240 | ty::Placeholder(..)
2241 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2242 bug!("`ptr_metadata_ty` applied to unexpected type: {:?}", tail)
2247 /// When we create a closure, we record its kind (i.e., what trait
2248 /// it implements) into its `ClosureSubsts` using a type
2249 /// parameter. This is kind of a phantom type, except that the
2250 /// most convenient thing for us to are the integral types. This
2251 /// function converts such a special type into the closure
2252 /// kind. To go the other way, use
2253 /// `tcx.closure_kind_ty(closure_kind)`.
2255 /// Note that during type checking, we use an inference variable
2256 /// to represent the closure kind, because it has not yet been
2257 /// inferred. Once upvar inference (in `rustc_typeck/src/check/upvar.rs`)
2258 /// is complete, that type variable will be unified.
2259 pub fn to_opt_closure_kind(&self) -> Option<ty::ClosureKind> {
2261 Int(int_ty) => match int_ty {
2262 ty::IntTy::I8 => Some(ty::ClosureKind::Fn),
2263 ty::IntTy::I16 => Some(ty::ClosureKind::FnMut),
2264 ty::IntTy::I32 => Some(ty::ClosureKind::FnOnce),
2265 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2268 // "Bound" types appear in canonical queries when the
2269 // closure type is not yet known
2270 Bound(..) | Infer(_) => None,
2272 Error(_) => Some(ty::ClosureKind::Fn),
2274 _ => bug!("cannot convert type `{:?}` to a closure kind", self),
2278 /// Fast path helper for testing if a type is `Sized`.
2280 /// Returning true means the type is known to be sized. Returning
2281 /// `false` means nothing -- could be sized, might not be.
2283 /// Note that we could never rely on the fact that a type such as `[_]` is
2284 /// trivially `!Sized` because we could be in a type environment with a
2285 /// bound such as `[_]: Copy`. A function with such a bound obviously never
2286 /// can be called, but that doesn't mean it shouldn't typecheck. This is why
2287 /// this method doesn't return `Option<bool>`.
2288 pub fn is_trivially_sized(&self, tcx: TyCtxt<'tcx>) -> bool {
2290 ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
2301 | ty::GeneratorWitness(..)
2305 | ty::Error(_) => true,
2307 ty::Str | ty::Slice(_) | ty::Dynamic(..) | ty::Foreign(..) => false,
2309 ty::Tuple(tys) => tys.iter().all(|ty| ty.expect_ty().is_trivially_sized(tcx)),
2311 ty::Adt(def, _substs) => def.sized_constraint(tcx).is_empty(),
2313 ty::Projection(_) | ty::Param(_) | ty::Opaque(..) => false,
2315 ty::Infer(ty::TyVar(_)) => false,
2318 | ty::Placeholder(..)
2319 | ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
2320 bug!("`is_trivially_sized` applied to unexpected type: {:?}", self)
2326 /// Extra information about why we ended up with a particular variance.
2327 /// This is only used to add more information to error messages, and
2328 /// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
2329 /// may lead to confusing notes in error messages, it will never cause
2330 /// a miscompilation or unsoundness.
2332 /// When in doubt, use `VarianceDiagInfo::default()`
2333 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq, PartialOrd, Ord)]
2334 pub enum VarianceDiagInfo<'tcx> {
2335 /// No additional information - this is the default.
2336 /// We will not add any additional information to error messages.
2339 /// We switched our variance because a generic argument occurs inside
2340 /// the invariant generic argument of another type.
2342 /// The generic type containing the generic parameter
2343 /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
2345 /// The index of the generic parameter being used
2346 /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
2351 impl<'tcx> VarianceDiagInfo<'tcx> {
2352 /// Mirrors `Variance::xform` - used to 'combine' the existing
2353 /// and new `VarianceDiagInfo`s when our variance changes.
2354 pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
2355 // For now, just use the first `VarianceDiagInfo::Invariant` that we see
2357 VarianceDiagInfo::None => other,
2358 VarianceDiagInfo::Invariant { .. } => self,